It is common for contaminants and pollutants to find their way into residential waterways. The most common of these in Rome’s rivers are dirt and fertilizers, according to Eric Lindberg, Rome-Floyd environmental director.
Others common contaminants include trash, stormwater runoff carrying oils, cigarette butts and other harmful materials and animal waste contaminants in smaller feeding streams. Although the majority of the contaminants are relatively common in residential waterways, the Coosa River basin has had an additional challenge in the form of polychlorinated biphenyls, or PCBs.
What is a PCB?
Polychlorinated biphenyls are oil-based chemical compounds that were used by General Electric as an insulator and coolant in transformers produced at GE plants, including the one in Rome.
Click to see more about PCB's on Berry College's War for Water web page.
Since the local plant’s doors opened in 1953 until the late 1970s, the GE plant used PCBs in the production of transformers, according to Richard Lester, GE’s Rome facilities and team leader.
Some believed that PCBs would be an excellent protection against termite infestation in the home. However, while many employees carried PCBs home, it was not part of regular plant practice.
The use of PCBs became heavily regulated in 1979, after they were found to share common traits with other toxic chemical compounds. By then, however, the contaminated area in Rome encompassed much of the GE site and other nearby properties.
GE employees who worked directly with the PCBs were not, surprisingly, the most highly contaminated. Lindberg, who has studied the effects of PCBs on the environment for more than a decade, said that while there are no immediate health problems caused by exposure, studies have shown that PCBs are a precursor to various cancers and can cause lower birth weights.
However, the presence and effects of PCBs are even greater in animals, he said.
PCBs are a neurotoxin when consumed by animals, destroying brain cells and remaining in the body even after death, according to Christine Clolinger, a senior environmental science major at Berry College and student carbon neutrality manager of environmental compliance and sustainability at Berry.
“PCBs are now likely present in every animal and human in the world,” Lindberg said.
Relic of the past
The General Electric plant shut down production in 1997 because of the company’s inability to compete in the medium-sized transformer market, Lester said.
“GE never intended to pack up and leave,” he said, it was simply a matter of losing money on the product.
With a crew of 15 employees, down from roughly 1,800 during production, the facility is now operating as a large water treatment facility for groundwater and storm water. The parts of the plant that aren’t used as part of the water treatment facilities are used for little other than storage.
“The few things stored in the warehouses will be removed soon and then the surrounding buildings will be completely empty,” said Lester.
Dedicated to treating water
At the former factory, GE now processes both stormwater runoff and ground water. Lester explained that in 1990, the plant began to treat rainwater that fell on the site by collecting the water found in storm drains and ditches and running it through a variety of filters and chemicals to separate the PCB material from the water before it is released back into community streams.
Storm water drainage must be treated because the plant’s storm drainage system outputs into Horseleg Creek. Smaller streams like Horseleg eventually flow into the Coosa River system, the primary source of Rome’s drinking water, but this is downstream from any intake by the city. Untreated stormwater runoff can bring the chemicals and pollutants that are on the ground or on the roadways into the nearest river, Lester said.
Groundwater underneath the plant must also be treated and sent to Rome’s sewage treatment facility, even though the GE-treated groundwater is cleaner than the water that comes out of Rome’s sewage treatment plant, according to Lester. He explained that this is because the plant has stricter regulations that it must meet, regulations set by the Georgia Environmental Protection Division.
GE began treating groundwater at the Rome plant in 2001. In treating the water, PCB sludge is separated and stored in a holding tank. This sludge is dewatered periodically and then shipped to the nearest chemical waste landfill, in Emelle, Alabama whenever necessary.
What else has GE done?
To date, GE has taken more than 30,000 soil samples in the Floyd county area to monitor PCB levels. Cleanup has been heavily focused in areas along Little Dry Creek and Tolbert Park, Lester said. A total of 101 houses have been investigated in the area, investigations spurred in a self-reporting system by which concerned homeowners ask to have their property inspected, according to Lester. GE has already treated several residential properties in the Floyd county area.
There are an additional 123 acres around the plant site that GE has already offered to donate to Rome. Lester said this property has been cleaned and meets the Georgia EPA’s requirements for commercial, industrial or recreational use. Lester said that there are still places to investigate and clean up, however, and that this year GE’s cleanup focus has been to treat a storm water drainage ditch that runs behind the Walmart on Shorter Avenue.
What can residents do?
People interested in assisting in river clean up or in participating in the Adopt-a-Stream program can contact the Coosa River Basin Initiative. The organization posts on its website its scheduled river cleanup days. Residents can also contact the Rome-Floyd County River Center to become a part of Adopt-a-Stream, Lindberg said.
2011年5月29日星期日
A second prerequisite for cost-effective processing
GaN is a promising material for next-generation power devices with a performance beyond what is possible with silicon. Imec has recently succeeded in producing 200mm GaN-on-Si wafers with crack-free surfaces and a bow of less than 50µm. The wafers were made using an advanced MOCVD system from Applied Materials. The ability to use 200mm wafers is an important milestone, because it brings processing in reach of regular high-productivity 200mm fabs, allowing for an important cost reduction compared to processing smaller wafers on dedicated processing lines.
A second prerequisite for cost-effective processing, next to the wafer size, is that power devices can be fabricated with processes that are compatible with standard CMOS processes and tools. Imec proved this by processing its GaN-on-Si wafers using standard CMOS tools, yielding functional GaN MISHEMTs (metal-insulator-semiconductor HEMT). All equipment was verified for its capability to handle the wafers, and required only minimal adjustments in software and hardware. Conventionally, gold is used for ohmic contacts and gate structures in power devices, but it makes GaN processing incompatible with conventional CMOS processing. To overcome this, imec based the ohmic contact formation on an Au-free metallization system, and modified the Schottky gate to a gate dielectric based gold-free metal-insulator-semiconductor (MIS) structure. This introduction of the MISHEMT structure had the added advantage of reducing the high leakage current of conventional HEMTs.
A second prerequisite for cost-effective processing, next to the wafer size, is that power devices can be fabricated with processes that are compatible with standard CMOS processes and tools. Imec proved this by processing its GaN-on-Si wafers using standard CMOS tools, yielding functional GaN MISHEMTs (metal-insulator-semiconductor HEMT). All equipment was verified for its capability to handle the wafers, and required only minimal adjustments in software and hardware. Conventionally, gold is used for ohmic contacts and gate structures in power devices, but it makes GaN processing incompatible with conventional CMOS processing. To overcome this, imec based the ohmic contact formation on an Au-free metallization system, and modified the Schottky gate to a gate dielectric based gold-free metal-insulator-semiconductor (MIS) structure. This introduction of the MISHEMT structure had the added advantage of reducing the high leakage current of conventional HEMTs.
2011年5月25日星期三
Primary school kids win gold awards for invention
GEORGE TOWN: Three primary school students who turned their frustration into invention won gold awards with their insulated bag that keeps their food warm until recess time.
The students, Wong Kai Wern, 10, Tan Su Fern and Jonathan Aeruthayan, both 12, from SJK (C) Shih Chung Cawangan, received the award during the 22nd International Invention and Technology Exhibition (ITEX ‘11) and Asian Young Inventors Exhibition (AYIE2011) in Kuala Lumpur held on Saturday.
Kai Wern said the idea came about after they got tired of eating food, which they brought from home, that had turned cold during break time.
“We discussed the idea during our Science Club meeting and decided to do something about it,” said the Standard Four pupil, who aspires to be a Science professor.
They then took about a month’s time to finalise the Eco-Friendly Insulated Bag by using sugar cane bagasse.
Jonathan, who aims to be a scientist, said that besides being a good insulator, the bagasse was light, non-toxic and biodegradable.
Su Fern said they had carried out several tests and were satisfied with the results of the insulator bag.
“It can keep food warm or cold and the bag is also suitable to keep milk warm for a baby.
“It can also be used for school, work and picnics,” said the girl, whose ambition is to be a doctor.
A total of 400 teams from primary and secondary schools took part in the Malaysian Young Inventors Competition.
Kai Wern, Jonathan and Su Fern emerged champions in the primary school category.
The three also won the World Intellectual Property Organisation Awards for Best Young Inventors (Primary School) and Best Asian Young Inventors Cup 2011 during the exhibition.
The students, Wong Kai Wern, 10, Tan Su Fern and Jonathan Aeruthayan, both 12, from SJK (C) Shih Chung Cawangan, received the award during the 22nd International Invention and Technology Exhibition (ITEX ‘11) and Asian Young Inventors Exhibition (AYIE2011) in Kuala Lumpur held on Saturday.
Kai Wern said the idea came about after they got tired of eating food, which they brought from home, that had turned cold during break time.
“We discussed the idea during our Science Club meeting and decided to do something about it,” said the Standard Four pupil, who aspires to be a Science professor.
They then took about a month’s time to finalise the Eco-Friendly Insulated Bag by using sugar cane bagasse.
Jonathan, who aims to be a scientist, said that besides being a good insulator, the bagasse was light, non-toxic and biodegradable.
Su Fern said they had carried out several tests and were satisfied with the results of the insulator bag.
“It can keep food warm or cold and the bag is also suitable to keep milk warm for a baby.
“It can also be used for school, work and picnics,” said the girl, whose ambition is to be a doctor.
A total of 400 teams from primary and secondary schools took part in the Malaysian Young Inventors Competition.
Kai Wern, Jonathan and Su Fern emerged champions in the primary school category.
The three also won the World Intellectual Property Organisation Awards for Best Young Inventors (Primary School) and Best Asian Young Inventors Cup 2011 during the exhibition.
Cheil Industries Made New 19.9 Billion Won investment in OLED Equipment
On May 24, Cheil Industries announced that they decided to invest total of 19.9 billion won in building production line for Electron Transport Layer (ETL).
Hole Transport Layer (HTL). Organic Insulator (PDL) material, major materials of AM OLED.
They will complete the construction of production facilities by the end of October. 10.8 billion won out of total investment will go to ETL, HTL material facilities, and 9.1 billion won will go to PDL material production line.
Cheil Industries plans to supply medium-sized AM OLED material, such as smartphone, to Samsung Mobile Display beginning 2nd half of the year. Recently, they also successfully developed large AM OLED ETL material such as TV and etc.
Hole Transport Layer (HTL). Organic Insulator (PDL) material, major materials of AM OLED.
They will complete the construction of production facilities by the end of October. 10.8 billion won out of total investment will go to ETL, HTL material facilities, and 9.1 billion won will go to PDL material production line.
Cheil Industries plans to supply medium-sized AM OLED material, such as smartphone, to Samsung Mobile Display beginning 2nd half of the year. Recently, they also successfully developed large AM OLED ETL material such as TV and etc.
2011年5月22日星期日
Cargill plant to turn soy oil into electrical fluid
Cargill officially opened a new operation at its Wichita oil seeds production plant -- turning soybean oil into electrical insulation fluid.
The company will make Cooper Power Systems Envirotemp FR3 dielectric fluid, a nontoxic and biodegradable fluid used in energy line transformers, to increase the performance of transformers during peak energy use periods.
The primary customer is Cooper Power Systems, a global maker of medium- and high-voltage electrical equipment.
The company spent $2.6 million for equipment to remove some ingredients and add others to its soybean oil to make it a better electrical insulator, said Michael Hora, Commercialization Engineer for Cargill Industrial Oils and Lubricants.
The company also has a plant in Chicago that does this, he said.
"We are always searching for new ways to use plant derived materials in our work with industrial customers to improve their products," Dave Roesser, general manager of Cargill's Industrial Oils and Lubricants group, said in a statement.
The company collaborated with Cooper Power Systems to produce the fluid.
Cargill has operated its Dressing, Sauces and Oils business in Wichita since 1981. Cargill also has the headquarters of its Meat Solutions division and a Horizon Milling flour mill in Wichita. Cargill has approximately 1,100 Wichita-based employees.
The company will make Cooper Power Systems Envirotemp FR3 dielectric fluid, a nontoxic and biodegradable fluid used in energy line transformers, to increase the performance of transformers during peak energy use periods.
The primary customer is Cooper Power Systems, a global maker of medium- and high-voltage electrical equipment.
The company spent $2.6 million for equipment to remove some ingredients and add others to its soybean oil to make it a better electrical insulator, said Michael Hora, Commercialization Engineer for Cargill Industrial Oils and Lubricants.
The company also has a plant in Chicago that does this, he said.
"We are always searching for new ways to use plant derived materials in our work with industrial customers to improve their products," Dave Roesser, general manager of Cargill's Industrial Oils and Lubricants group, said in a statement.
The company collaborated with Cooper Power Systems to produce the fluid.
Cargill has operated its Dressing, Sauces and Oils business in Wichita since 1981. Cargill also has the headquarters of its Meat Solutions division and a Horizon Milling flour mill in Wichita. Cargill has approximately 1,100 Wichita-based employees.
Power outage hits citizens
More than 1,000 members of Federated Rural Electric, Jackson, lost power for an hour or more Thursday after three insulators failed at a substation.
The outage occurred at 4:37 p.m., first affecting West Lakefield, Miloma, Minneota and Round Lake substations, and an hour later, Minneota, Round Lake, Middletown, Enterprise, Wisconsin, Ceylon, Dunnell, Wilbert and East Chain substations.
More than 2,800 members were affected by the transmission link blinks around 5:37 p.m. and 6:30 p.m. for three minutes.
“Federated had three crews out helping the Great River Energy crew pinpoint the problem and restore power as quickly as possible,” said Rick Burud, Federated’s general manager.
The outage was caused by insulator failures at a substation owned by Ewington Wind near Spafford Corner, which is connected to the 69 KV transmission line, which tripped off power to Federated’s nine substations. Power was restored to most of them within minutes, by re-routing power with Great River Energy’s automatic switch.
West Lakefield’s power was restored at 6:04 p.m. Line crews tried to reroute directly to the Miloma substation by opening a switch at 6:30 p.m., which blinked power for a few minutes to the nine substations. The second problem and transmission blink was caused by a failed circuit switcher at ITC Transmission’s Heron Lake substation. Power was restored to the Miloma substation around 6:43 p.m.
The outage occurred at 4:37 p.m., first affecting West Lakefield, Miloma, Minneota and Round Lake substations, and an hour later, Minneota, Round Lake, Middletown, Enterprise, Wisconsin, Ceylon, Dunnell, Wilbert and East Chain substations.
More than 2,800 members were affected by the transmission link blinks around 5:37 p.m. and 6:30 p.m. for three minutes.
“Federated had three crews out helping the Great River Energy crew pinpoint the problem and restore power as quickly as possible,” said Rick Burud, Federated’s general manager.
The outage was caused by insulator failures at a substation owned by Ewington Wind near Spafford Corner, which is connected to the 69 KV transmission line, which tripped off power to Federated’s nine substations. Power was restored to most of them within minutes, by re-routing power with Great River Energy’s automatic switch.
West Lakefield’s power was restored at 6:04 p.m. Line crews tried to reroute directly to the Miloma substation by opening a switch at 6:30 p.m., which blinked power for a few minutes to the nine substations. The second problem and transmission blink was caused by a failed circuit switcher at ITC Transmission’s Heron Lake substation. Power was restored to the Miloma substation around 6:43 p.m.
2011年5月18日星期三
Judge Kalauli resigns as Magistrate at Fredonia Town Council
The Fredonia Town Council began with public comment from Sondra Bistline. Bistline stated she had heard about the Forest Service Travel Management plan and wondered if there was cause for concern.
Council member Brent Mackelprang replied, “Every citizen in this community should be very concerned with any decision made by the federal government.” He went on to explain that the Forest Service had denied the town coordination status regarding the plan.
Bistline said it was the public comment period for the plan and wondered if it would do any good to comment.
Mackelprang encouraged her and everyone in the community to comment. He explained that most public comments on this project actually come from special interest groups and people who have never even been to the area, so local input is vital.
Next, Mackelprang requested the office research previous council minutes for him. He stated he thought about the decision made at the last meeting regarding the marshal and town manager position and seemed to recall the former council had made a decision that the manager could not also be a department head. He asked that the decision be researched so the council could review.
Town Manager Dan Watson reported on the water project. He explained the contractors were finishing and working on the punch list.
Next, he updated the council on the bid bond for the tank project. Previously, they believed the bond to be fraudulent. After further research, it has been determined that it is not fraudulent, but more of a clerical error by the bond company. Watson now feels it is between the construction company, the insurance company and Sunrise Engineering to figure out how the town can collect the $12,271.54 on the bond.
Watson explained the recent power outage was caused by a faulty insulator, which formed an arc, frying the transformer. It is now imperative that the town change out the transformer, which the council had voted on previously.
The council moved onto the agenda items. Mark Overas submitted his resignation as Planning and Zoning chair. Mayor Heaton asked that the opening be advertised, so those interested could submit letters of interest.
The council next accepted the resignation of Mitch Kalauli as Magistrate. They expressed their appreciation for his dedication to the community. He will be missed. The council approved the posting of the position.
Heidi Koeller, court trainer from Flagstaff, approached the council regarding the severity of not having a judge. She explained that on Thursday at 4 p.m., Kalauli would no longer be Magistrate. The town must have a judge.
The council requested Watson to speak with Judge Heaton and Judge Baron to see if they may fill in until a new Magistrate could be appointed.
The possibility of a new rental contract for the medical center was discussed. Watson stated he had been negotiating with Mark Overas regarding the contract and they proposed $750 plus utilities with an automatic 3% increase each year. The council requested research be done to be sure the low rental amount was enough to cover costs and start a repair and maintenance fund for the building.
Mandy Grover was chosen for the pool manager position for 2011, with Josh Finicum as assistant. Lifeguards and pool cleaners were also approved for the season.
Town contract services had recently been put out to bid. The council reviewed the proposals and voted as follows: the contract for propane was given to low bidder, Coast Gas. Summer Softball director to Randi Utter and Derran (Hoss) Tait. Pool supplies/maintenance and repair awarded to Shawn Warner. Bulk fuel to Jenkins Oil. Janitorial services to Sonya Kimball. HVAC to Jimeco. Port-a-potties to RD Enterprises.
Justin Mackelprang and Jacob Weber were approved as the newest members of the volunteer fire department.
The town vehicle policy was discussed again. Watson stated he had made the changes the council had requested, including a reference to the law enforcement policy.
Watson stated council member Alvy Johnson had requested he add that all Public Works employees be required to obtain and maintain valid Commercial Driver’s Licenses. Watson said he made the change. The council decided to give all Public Works employees six months to get their CDLs beginning June 1, 2011. Watson stated he would give a copy of the new policy to each of the employees.
The council then discussed the welcome center/museum Dixon Spendlove is working on. Watson stated Spendlove is currently a little over $15,000, and believes he can finish it with an additional $5,000.
Alvin Johnson asked where the money is coming from. Watson stated it would have to come out of contingency funds.
Jennifer Lukus stated she felt it was a lot of money, but it would be difficult to not finish the project.
Mackelprang felt it was the best use of that area and building.
Town Clerk TinaMarie Horlacher expressed her concern, however, stating that every other department had ceased spending and had worked very hard to work under the limited funding.
The council authorized an additional $5,000 for the museum.
Council member Brent Mackelprang replied, “Every citizen in this community should be very concerned with any decision made by the federal government.” He went on to explain that the Forest Service had denied the town coordination status regarding the plan.
Bistline said it was the public comment period for the plan and wondered if it would do any good to comment.
Mackelprang encouraged her and everyone in the community to comment. He explained that most public comments on this project actually come from special interest groups and people who have never even been to the area, so local input is vital.
Next, Mackelprang requested the office research previous council minutes for him. He stated he thought about the decision made at the last meeting regarding the marshal and town manager position and seemed to recall the former council had made a decision that the manager could not also be a department head. He asked that the decision be researched so the council could review.
Town Manager Dan Watson reported on the water project. He explained the contractors were finishing and working on the punch list.
Next, he updated the council on the bid bond for the tank project. Previously, they believed the bond to be fraudulent. After further research, it has been determined that it is not fraudulent, but more of a clerical error by the bond company. Watson now feels it is between the construction company, the insurance company and Sunrise Engineering to figure out how the town can collect the $12,271.54 on the bond.
Watson explained the recent power outage was caused by a faulty insulator, which formed an arc, frying the transformer. It is now imperative that the town change out the transformer, which the council had voted on previously.
The council moved onto the agenda items. Mark Overas submitted his resignation as Planning and Zoning chair. Mayor Heaton asked that the opening be advertised, so those interested could submit letters of interest.
The council next accepted the resignation of Mitch Kalauli as Magistrate. They expressed their appreciation for his dedication to the community. He will be missed. The council approved the posting of the position.
Heidi Koeller, court trainer from Flagstaff, approached the council regarding the severity of not having a judge. She explained that on Thursday at 4 p.m., Kalauli would no longer be Magistrate. The town must have a judge.
The council requested Watson to speak with Judge Heaton and Judge Baron to see if they may fill in until a new Magistrate could be appointed.
The possibility of a new rental contract for the medical center was discussed. Watson stated he had been negotiating with Mark Overas regarding the contract and they proposed $750 plus utilities with an automatic 3% increase each year. The council requested research be done to be sure the low rental amount was enough to cover costs and start a repair and maintenance fund for the building.
Mandy Grover was chosen for the pool manager position for 2011, with Josh Finicum as assistant. Lifeguards and pool cleaners were also approved for the season.
Town contract services had recently been put out to bid. The council reviewed the proposals and voted as follows: the contract for propane was given to low bidder, Coast Gas. Summer Softball director to Randi Utter and Derran (Hoss) Tait. Pool supplies/maintenance and repair awarded to Shawn Warner. Bulk fuel to Jenkins Oil. Janitorial services to Sonya Kimball. HVAC to Jimeco. Port-a-potties to RD Enterprises.
Justin Mackelprang and Jacob Weber were approved as the newest members of the volunteer fire department.
The town vehicle policy was discussed again. Watson stated he had made the changes the council had requested, including a reference to the law enforcement policy.
Watson stated council member Alvy Johnson had requested he add that all Public Works employees be required to obtain and maintain valid Commercial Driver’s Licenses. Watson said he made the change. The council decided to give all Public Works employees six months to get their CDLs beginning June 1, 2011. Watson stated he would give a copy of the new policy to each of the employees.
The council then discussed the welcome center/museum Dixon Spendlove is working on. Watson stated Spendlove is currently a little over $15,000, and believes he can finish it with an additional $5,000.
Alvin Johnson asked where the money is coming from. Watson stated it would have to come out of contingency funds.
Jennifer Lukus stated she felt it was a lot of money, but it would be difficult to not finish the project.
Mackelprang felt it was the best use of that area and building.
Town Clerk TinaMarie Horlacher expressed her concern, however, stating that every other department had ceased spending and had worked very hard to work under the limited funding.
The council authorized an additional $5,000 for the museum.
Hendrix Announces Availability Of Complete Line Of High Quality Covered Tap Wire, Ground Wire, and Tie Wire
Hendrix, a premier provider of high quality overhead and underground power distribution products, announces the availability of its complete line of covered tap wire, ground wire, and tie wire.
Tap Wire - Hendrix covered tap wire, a stranded or solid copper conductor covered with a 0.150-inch layer of flexible, black, thermoplastic elastomer, is used to provide a covered lead to connect an overhead phase conductor to equipment bushings.
Utilities are using covered tap wire for jumpers and connections on most bare wire applications to improve reliability. Using covered tap wire avoids outages due to wildlife contact with the energized tap. It is suitable for all overhead systems, including open wire, weatherproof, tree wire, and spacer cable. The tap wire can also be used in substation equipment connections to provide covered bus and as covered ground lead.
Hendrix tap wire is available in #2 AWG, #4 AWG (copper), and #6 AWG (copper) sizes. Custom cut lengths and packaging is an option. Hendrix tap wire has excellent ultraviolet and weathering characteristics, which maintain covering integrity. The tap wire's thermoplastic elastomer covering is more flexible and trains more easily than polyethylene covering.
Ground Wire - Hendrix insulated ground wire is ideal for utilities using covered ground wire on distribution pole tops to improve reliability and increase basic impulse level (BIL), or on transmission lines to get the ground wire down through the primary in lieu of standoffs. The insulating covering on the ground wire helps meet the BIL requirements when the ground wire is stapled to the pole.
Consisting of a copper conductor, an inner layer of unfilled high molecular weight polyethylene and an outer layer of proprietary black, track and ultraviolet resistant, high density polyethylene, Hendrix ground wire eliminates expensive "outriggers" required by bare grounds, provides a neater pole, and makes pole climbing and maintenance easier. Customized cut lengths and pre-stripped ends are available to facilitate rapid installation.
Tie Wire - Hendrix covered tie wire, which consists of a #4 AWG solid, fully annealed aluminum conductor covered by a 0.045-inch extruded layer of black thermoplastic rubber (TPR), is used primarily to tie a covered conductor to a Hendrix polyethylene pin type insulator. The covered tie wire eliminates tracking and erosion caused by the use of bare tie wire on a covered conductor. The conductor and covering are both flexible, and have no tendency to spring back. In addition, TPR covered tie wire grips cover the conductor better than PVC and other tie wires.
About Hendrix Aerial Cable & Systems
Hendrix Aerial Cable Systems is one of five operating divisions of Marmon Utility LLC, a provider of high-quality overhead and underground power distribution products located in Milford, NH. The division's benchmark product, Spacer Cable, formed the foundation of the company in 1951, solving local utilities' reliability problems, reducing weather-related outages, and providing options for areas difficult to engineer with standard bare wire systems. Today, Hendrix Spacer Cable is available at 15kV through 69 kV.
ISO 9001-certified Marmon Utility LLC is a member company of The Marmon Group, an international association of more than 125 business units that operate independently within diverse business sectors. Member companies have collective revenues of $7 billion.
Tap Wire - Hendrix covered tap wire, a stranded or solid copper conductor covered with a 0.150-inch layer of flexible, black, thermoplastic elastomer, is used to provide a covered lead to connect an overhead phase conductor to equipment bushings.
Utilities are using covered tap wire for jumpers and connections on most bare wire applications to improve reliability. Using covered tap wire avoids outages due to wildlife contact with the energized tap. It is suitable for all overhead systems, including open wire, weatherproof, tree wire, and spacer cable. The tap wire can also be used in substation equipment connections to provide covered bus and as covered ground lead.
Hendrix tap wire is available in #2 AWG, #4 AWG (copper), and #6 AWG (copper) sizes. Custom cut lengths and packaging is an option. Hendrix tap wire has excellent ultraviolet and weathering characteristics, which maintain covering integrity. The tap wire's thermoplastic elastomer covering is more flexible and trains more easily than polyethylene covering.
Ground Wire - Hendrix insulated ground wire is ideal for utilities using covered ground wire on distribution pole tops to improve reliability and increase basic impulse level (BIL), or on transmission lines to get the ground wire down through the primary in lieu of standoffs. The insulating covering on the ground wire helps meet the BIL requirements when the ground wire is stapled to the pole.
Consisting of a copper conductor, an inner layer of unfilled high molecular weight polyethylene and an outer layer of proprietary black, track and ultraviolet resistant, high density polyethylene, Hendrix ground wire eliminates expensive "outriggers" required by bare grounds, provides a neater pole, and makes pole climbing and maintenance easier. Customized cut lengths and pre-stripped ends are available to facilitate rapid installation.
Tie Wire - Hendrix covered tie wire, which consists of a #4 AWG solid, fully annealed aluminum conductor covered by a 0.045-inch extruded layer of black thermoplastic rubber (TPR), is used primarily to tie a covered conductor to a Hendrix polyethylene pin type insulator. The covered tie wire eliminates tracking and erosion caused by the use of bare tie wire on a covered conductor. The conductor and covering are both flexible, and have no tendency to spring back. In addition, TPR covered tie wire grips cover the conductor better than PVC and other tie wires.
About Hendrix Aerial Cable & Systems
Hendrix Aerial Cable Systems is one of five operating divisions of Marmon Utility LLC, a provider of high-quality overhead and underground power distribution products located in Milford, NH. The division's benchmark product, Spacer Cable, formed the foundation of the company in 1951, solving local utilities' reliability problems, reducing weather-related outages, and providing options for areas difficult to engineer with standard bare wire systems. Today, Hendrix Spacer Cable is available at 15kV through 69 kV.
ISO 9001-certified Marmon Utility LLC is a member company of The Marmon Group, an international association of more than 125 business units that operate independently within diverse business sectors. Member companies have collective revenues of $7 billion.
SDG&E Signs New Contracts with Soitec for 125 Megawatts of Solar Power in San Diego
These new agreements are separate from the three San Diego contracts the two companies signed in April for 30 MW of CPV-generated solar power. Combined, the five contracts SDG&E recently signed with Soitec represent five separate projects capable of generating a combined total of 155 MW of clean, renewable solar power, or enough energy to supply more than 60,000 homes. Both of the new proposed projects will be located in San Diego County and will be situated near SDG&E electric substations.
"Our projects with Soitec will bring local jobs to the community and will help us to meet our renewable energy goals," said James P. Avery, senior vice president of power supply for SDG&E. "We are very confident in our choice of technology and in Soitec's plans for a solar panel manufacturing facility in the San Diego region."
Today's announcement confirms the attractiveness of Soitec's renewable energy technology – which generates large amounts of power with industry-leading efficiency and low environmental impact – in areas such as Southern California with abundant sunshine.
"These new contracts with SDG&E reinforce Soitec's decision to build its new manufacturing site in the San Diego area, and confirms the importance of the U.S. market for our company," said Andre-Jacques Auberton-Herve, chief executive officer and chairman of the board of Soitec. "We are very pleased to have a direct role in bringing 'home grown' solar energy to the people of San Diego."
Soitec's new manufacturing facility will have an annual production capacity of 200 MW and will supply all of SDG&E's projects with Soitec with the Concentrix CPV technology, which produces power at a much higher efficiency relative to standard solar panels. At full capacity, Soitec's San Diego operations facility will generate up to 450 direct jobs and more than 1,000 indirect jobs. The factory location is expected to be announced this summer, with completion within 18 months of construction start.
The power contracts require approval from the California Public Utilities Commission.
"Our projects with Soitec will bring local jobs to the community and will help us to meet our renewable energy goals," said James P. Avery, senior vice president of power supply for SDG&E. "We are very confident in our choice of technology and in Soitec's plans for a solar panel manufacturing facility in the San Diego region."
Today's announcement confirms the attractiveness of Soitec's renewable energy technology – which generates large amounts of power with industry-leading efficiency and low environmental impact – in areas such as Southern California with abundant sunshine.
"These new contracts with SDG&E reinforce Soitec's decision to build its new manufacturing site in the San Diego area, and confirms the importance of the U.S. market for our company," said Andre-Jacques Auberton-Herve, chief executive officer and chairman of the board of Soitec. "We are very pleased to have a direct role in bringing 'home grown' solar energy to the people of San Diego."
Soitec's new manufacturing facility will have an annual production capacity of 200 MW and will supply all of SDG&E's projects with Soitec with the Concentrix CPV technology, which produces power at a much higher efficiency relative to standard solar panels. At full capacity, Soitec's San Diego operations facility will generate up to 450 direct jobs and more than 1,000 indirect jobs. The factory location is expected to be announced this summer, with completion within 18 months of construction start.
The power contracts require approval from the California Public Utilities Commission.
2011年5月15日星期日
Zittauer Wissenschaftler auf dem INMR- Weltkongress 2011 in Seoul
Because the expansion of the electricity system at the highest level of the currently technically feasible tensions in Asia takes place, the periodical INMR (Insulator News and Market Report), the specialists invited to the field of high voltage insulators to its World Congress 2011 in Seoul.
Professor Klaus-Dieter Haim from the Faculty of electrical engineering and computer science of the Hochschule Zittau / Görlitz was asked to give a talk about his specialty cable system with the theme "Material and design requirements for medium voltage cable accessories.
Of the 500 participants were about 10% from Germany. Among them alone, four speakers who have studied and graduated in Zittau.
The capital of South Korea, with 10 million and 18 million (and surrounding area) residents also reflects very well the contradictions between the electricity supply against super modern and very simple.
Professor Klaus-Dieter Haim from the Faculty of electrical engineering and computer science of the Hochschule Zittau / Görlitz was asked to give a talk about his specialty cable system with the theme "Material and design requirements for medium voltage cable accessories.
Of the 500 participants were about 10% from Germany. Among them alone, four speakers who have studied and graduated in Zittau.
The capital of South Korea, with 10 million and 18 million (and surrounding area) residents also reflects very well the contradictions between the electricity supply against super modern and very simple.
Limiting, not eliminating fat
“FAT-free,” “low-fat” and “high fat” seem to have an overbearing presence in our world. People are fat obsessed. It’s impossible to try to maintain a “fat-free” lifestyle.
Fat in food does do your body some good. It is a necessary nutrient. Fat provides essential fatty acids, from which your body makes molecules it needs to function properly. It acts as a wall of protection around. Your vital organs like your heart and kidneys. It also acts as an insulator for the body. Fat carries essentials (fat-soluble) vitamins A, D, E and K. These vitamins cannot be absorbed into your body without fat. Although a diet high in fat is unhealthy, fat is the ingredient that makes most foods taste better, because flavor adheres to fat. Fat can offer a concentrated source of energy because fats have a tendency to pack together if they're not in water, so they become a source for greater energy storage. Fat protects your internal organs from going into shock. It insulates the body in extreme temperature conditions. It also acts as an emergency fuel supply in times of illness. Extremely low-fat diets suck the oil right out of your skin. You need a certain amount of fat in your diet for skin to look healthy.
So, which fats are okay to eat and which ones are not? For nutritional purposes, fats can be divided into three categories: saturated, monounsaturated and polyunsaturated, which is based on the amount of hydrogen each one carries. Saturated fats have no more room for any additional hydrogen. An easy way to remember what’s a saturated fat is to think of animals. All animal fats, such as those found in meat, poultry, dairy products and eggs are saturated. Chocolate, coconut oil and products made with lard are also saturated fats. These are considered the least healthy forms of fat because they are the highest in cholesterol. Saturated fats can also cause the body itself to produce higher levels of cholesterol. Monounsaturated fats have a little extra room for hydrogen (one more atom) and are somewhat better for you than saturated fats. They are oils like olive, peanut and canola. Peanut butter and avocados are also monounsaturated fats. People usually think avocados are so fattening, but they’re not as bad as you think. They’re better than eating a saturated fat. Polyunsaturated fats have room for many more hydrogen atoms and are the healthiest form of fat. Corn oil is an example of polyunsaturated fat. Fish, soy, corn, sunflower and safflower oils are all polyunsaturated fats.
Eating too much fat results in some really harmful consequences. The obvious one is that fat makes you fat. Gram for gram, fat delivers more than twice as many calories as carbohydrates and protein. One gram of fat is equal to nine calories. You have to be really careful with fat-free foods, though, because they tend to be very fattening. Taking the fat out
loses the flavor, so food manufacturers compensate by adding other ingredients, like artificial flavorings, sugar and syrups, all of which are high in calories. Some fats are definitely easier to spot than others are. Butter, cream cheese, salad dressings, mayonnaise and cheese are all obvious fat foods. Meats like sausage, pepperoni, bologna, bacon, corned beef and hot dogs, are aren’t so obvious but they’re all high in fat. ice creams, coleslaw, pasta salads and potato salad are also high fat. Watching the fat in your diet is important and balancing your intake among fats, protein and carbohydrates is the best combination of good health.
Trying to eliminate fat from your diet is hardly the answer to better health. As I said earlier, fat is essential to your health. The key is to successfully replace the bad fat with good fat. If you let your fat intake fall below 20 percent of your calories from fat a day, you may start eating more volume of food because you’ll have a harder time getting full. Fats digest really slowly and they take the longest to exit your body. Every time you put on weight, your body makes new fat cells. Once these fat cells just hang out in your body waiting to get plumped up again. That’s why so many people who lose weight on a diet and go back to their old eating habits put on the weight so easily again.
Moderation is the key to success. You have to consciously make an effort to reduce your fat intake, but it’s not impossible. If you’re still eating dairy, choose low-fat dairy products whenever you can. Remove the skin from chicken and avoid eating the fried version. Trimming the fat around the meat you eat will help cut down on your fat. If you do eat meat, try eating lower fat selections. Try substituting turkey for any of your meat needs. It’s much lower in fat. Fish is an excellent source of protein and there are so many varieties you won’t get bored. Use caution when eating pasta, because the sauces can be major culprits of fat. If you eat eggs, go for egg whites. The yolk is loaded with cholesterol.
Most experts agree that limiting your daily fat intake to less than 30 percent of total calories consumed is the best approach to eating a healthy diet. Living a low fat lifestyle will pave the road for your total health.
Fat in food does do your body some good. It is a necessary nutrient. Fat provides essential fatty acids, from which your body makes molecules it needs to function properly. It acts as a wall of protection around. Your vital organs like your heart and kidneys. It also acts as an insulator for the body. Fat carries essentials (fat-soluble) vitamins A, D, E and K. These vitamins cannot be absorbed into your body without fat. Although a diet high in fat is unhealthy, fat is the ingredient that makes most foods taste better, because flavor adheres to fat. Fat can offer a concentrated source of energy because fats have a tendency to pack together if they're not in water, so they become a source for greater energy storage. Fat protects your internal organs from going into shock. It insulates the body in extreme temperature conditions. It also acts as an emergency fuel supply in times of illness. Extremely low-fat diets suck the oil right out of your skin. You need a certain amount of fat in your diet for skin to look healthy.
So, which fats are okay to eat and which ones are not? For nutritional purposes, fats can be divided into three categories: saturated, monounsaturated and polyunsaturated, which is based on the amount of hydrogen each one carries. Saturated fats have no more room for any additional hydrogen. An easy way to remember what’s a saturated fat is to think of animals. All animal fats, such as those found in meat, poultry, dairy products and eggs are saturated. Chocolate, coconut oil and products made with lard are also saturated fats. These are considered the least healthy forms of fat because they are the highest in cholesterol. Saturated fats can also cause the body itself to produce higher levels of cholesterol. Monounsaturated fats have a little extra room for hydrogen (one more atom) and are somewhat better for you than saturated fats. They are oils like olive, peanut and canola. Peanut butter and avocados are also monounsaturated fats. People usually think avocados are so fattening, but they’re not as bad as you think. They’re better than eating a saturated fat. Polyunsaturated fats have room for many more hydrogen atoms and are the healthiest form of fat. Corn oil is an example of polyunsaturated fat. Fish, soy, corn, sunflower and safflower oils are all polyunsaturated fats.
Eating too much fat results in some really harmful consequences. The obvious one is that fat makes you fat. Gram for gram, fat delivers more than twice as many calories as carbohydrates and protein. One gram of fat is equal to nine calories. You have to be really careful with fat-free foods, though, because they tend to be very fattening. Taking the fat out
loses the flavor, so food manufacturers compensate by adding other ingredients, like artificial flavorings, sugar and syrups, all of which are high in calories. Some fats are definitely easier to spot than others are. Butter, cream cheese, salad dressings, mayonnaise and cheese are all obvious fat foods. Meats like sausage, pepperoni, bologna, bacon, corned beef and hot dogs, are aren’t so obvious but they’re all high in fat. ice creams, coleslaw, pasta salads and potato salad are also high fat. Watching the fat in your diet is important and balancing your intake among fats, protein and carbohydrates is the best combination of good health.
Trying to eliminate fat from your diet is hardly the answer to better health. As I said earlier, fat is essential to your health. The key is to successfully replace the bad fat with good fat. If you let your fat intake fall below 20 percent of your calories from fat a day, you may start eating more volume of food because you’ll have a harder time getting full. Fats digest really slowly and they take the longest to exit your body. Every time you put on weight, your body makes new fat cells. Once these fat cells just hang out in your body waiting to get plumped up again. That’s why so many people who lose weight on a diet and go back to their old eating habits put on the weight so easily again.
Moderation is the key to success. You have to consciously make an effort to reduce your fat intake, but it’s not impossible. If you’re still eating dairy, choose low-fat dairy products whenever you can. Remove the skin from chicken and avoid eating the fried version. Trimming the fat around the meat you eat will help cut down on your fat. If you do eat meat, try eating lower fat selections. Try substituting turkey for any of your meat needs. It’s much lower in fat. Fish is an excellent source of protein and there are so many varieties you won’t get bored. Use caution when eating pasta, because the sauces can be major culprits of fat. If you eat eggs, go for egg whites. The yolk is loaded with cholesterol.
Most experts agree that limiting your daily fat intake to less than 30 percent of total calories consumed is the best approach to eating a healthy diet. Living a low fat lifestyle will pave the road for your total health.
2011年5月10日星期二
IHS: Intel's tri-gates to keep ARM at bay
Intel Corp.'s recently announced 22-nm tri-gate transistor technology gives the world's No. 1 chip vendor the microprocessor ammunition it needs to make headway in the smartphone and media tablet market while simultaneously fighting off a potential incursion into the PC business from devices based on the architecture of ARM Holdings plc, according to a new report by market research firm IHS iSuppli.
Intel (Santa Clara, Calif.) last week rolled out its 22-nm process, featuring a twist— Intel's long-awaited 3-D transistor design, known as tri-gate. According to Intel, chips based on this technology will consume less than half the power of devices using 32-nm technology and conventional planar transistors, while delivering the same level of performance.
"A 50 percent reduction in power consumption is significant," said Matthew Wilkins, principal analyst for compute platforms research at HIS, in a statement. "The less power your electronic device consumes, the longer the battery will last, and the longer a user can be truly mobile."
Intel has long sought to increase its presence in mobile devices, where chips based on the more power efficient ARM architecture have proven vastly more popular. Intel's Atom processor has been unable to stop ARM's momentum in the handheld front, although Intel executives have said Atom will be designed into at least one smartphone this year. A persistent lack of success in the mobile arena was widely viewed as the reason that Anand Chandrasekher, senior vice president and general manager of Intel's Ultra Mobility Group, abruptly resigned in March.
"Marching down the nanometer curve will definitely help Intel to penetrate the market for mobile devices," said Francis Sideco, principal analyst for wireless communications at IHS. "That, however, is only one part of the equation, as power efficiency in these types of devices also requires system-level optimization of the processors."
A 32-nm planar transistor (left) in which the current—represented by yellow dots—flows in a plane underneath the gate, compared to a 22-nm tri-gate transistor with current flowing on three sides of a vertical fin. Source: Intel.
Intel is also facing a threat from ARM-based devices in its traditional area of dominance, the PC microprocessor. Microsoft's announcement in January that the next version of the Windows operating system would run on both the X86 and ARM architectures has led to speculation that more power-efficient, lower cost ARM-based processors could eat into Intel's marketshare, particularly in the notebook segment.
But, according to IHS, tri-gate technology will make X86 a better matchup for ARM. In terms of power consumption, X86 will become more competitive with ARM in low-power devices such as notebooks, netbooks, tablets and smart phones, IHS said.
IHS noted that the concept of a 3-D structure is not new in chip manufacturing—Taiwan Semiconductor Manufacturing Co. Ltd. (TSMC) and IBM have been developing such technology for several years. However, unlike the TSMC/IBM effort, Intel’s tri-gate is ready for volume production—representing a significant technological achievement, according to IHS.
"The capability to go into high-volume production should give Intel a two- to three-year manufacturing advantage over its competitors," sad Len Jelinek, director and chief analyst for semiconductor manufacturing at IHS. Other advantages of Intel’s Tri-Gate technology include its scalability, cost, product roadmap and elimination of the use of special wafers, Jelinek said.
Tri-gate can be shrunk to the sub-20nm level when the next-generation of lithography tools become available, allowing further gains in performance, power savings and cost reduction, IHS said. The manufacturing cost of tri-gate technology is only about 2 to 3 percent more per device compared to conventional planar technology, according to IHS.
Tri-gate also gives Intel a roadmap to extend its 22-nm semiconductor manufacturing technology to the Atom platform, which could result in the introduction of a low-power microarchitecture that can be incorporated into cell phones, IHS said. Transitioning to a tri-gate transistor also gives Intel the capability to manufacture a fully depleted transistor without having to use a silicon-on-insulator (SOI) structure, eliminating the need to use more expensive SOI wafers, according to IHS.
Wilkins said Advanced Micro Devices Inc. (AMD), Intel’s main competitor in the PC and server X86 microprocessor markets, has been working on reducing the power consumption of its chips for a number of years now, much like Intel. AMD recently launched its accelerated processing units (APUs), which combine the microprocessor core and graphics processor on the same silicon. The aim of AMD’s chips is also to extend the battery life at the system level, Wilkins said.
Intel (Santa Clara, Calif.) last week rolled out its 22-nm process, featuring a twist— Intel's long-awaited 3-D transistor design, known as tri-gate. According to Intel, chips based on this technology will consume less than half the power of devices using 32-nm technology and conventional planar transistors, while delivering the same level of performance.
"A 50 percent reduction in power consumption is significant," said Matthew Wilkins, principal analyst for compute platforms research at HIS, in a statement. "The less power your electronic device consumes, the longer the battery will last, and the longer a user can be truly mobile."
Intel has long sought to increase its presence in mobile devices, where chips based on the more power efficient ARM architecture have proven vastly more popular. Intel's Atom processor has been unable to stop ARM's momentum in the handheld front, although Intel executives have said Atom will be designed into at least one smartphone this year. A persistent lack of success in the mobile arena was widely viewed as the reason that Anand Chandrasekher, senior vice president and general manager of Intel's Ultra Mobility Group, abruptly resigned in March.
"Marching down the nanometer curve will definitely help Intel to penetrate the market for mobile devices," said Francis Sideco, principal analyst for wireless communications at IHS. "That, however, is only one part of the equation, as power efficiency in these types of devices also requires system-level optimization of the processors."
A 32-nm planar transistor (left) in which the current—represented by yellow dots—flows in a plane underneath the gate, compared to a 22-nm tri-gate transistor with current flowing on three sides of a vertical fin. Source: Intel.
Intel is also facing a threat from ARM-based devices in its traditional area of dominance, the PC microprocessor. Microsoft's announcement in January that the next version of the Windows operating system would run on both the X86 and ARM architectures has led to speculation that more power-efficient, lower cost ARM-based processors could eat into Intel's marketshare, particularly in the notebook segment.
But, according to IHS, tri-gate technology will make X86 a better matchup for ARM. In terms of power consumption, X86 will become more competitive with ARM in low-power devices such as notebooks, netbooks, tablets and smart phones, IHS said.
IHS noted that the concept of a 3-D structure is not new in chip manufacturing—Taiwan Semiconductor Manufacturing Co. Ltd. (TSMC) and IBM have been developing such technology for several years. However, unlike the TSMC/IBM effort, Intel’s tri-gate is ready for volume production—representing a significant technological achievement, according to IHS.
"The capability to go into high-volume production should give Intel a two- to three-year manufacturing advantage over its competitors," sad Len Jelinek, director and chief analyst for semiconductor manufacturing at IHS. Other advantages of Intel’s Tri-Gate technology include its scalability, cost, product roadmap and elimination of the use of special wafers, Jelinek said.
Tri-gate can be shrunk to the sub-20nm level when the next-generation of lithography tools become available, allowing further gains in performance, power savings and cost reduction, IHS said. The manufacturing cost of tri-gate technology is only about 2 to 3 percent more per device compared to conventional planar technology, according to IHS.
Tri-gate also gives Intel a roadmap to extend its 22-nm semiconductor manufacturing technology to the Atom platform, which could result in the introduction of a low-power microarchitecture that can be incorporated into cell phones, IHS said. Transitioning to a tri-gate transistor also gives Intel the capability to manufacture a fully depleted transistor without having to use a silicon-on-insulator (SOI) structure, eliminating the need to use more expensive SOI wafers, according to IHS.
Wilkins said Advanced Micro Devices Inc. (AMD), Intel’s main competitor in the PC and server X86 microprocessor markets, has been working on reducing the power consumption of its chips for a number of years now, much like Intel. AMD recently launched its accelerated processing units (APUs), which combine the microprocessor core and graphics processor on the same silicon. The aim of AMD’s chips is also to extend the battery life at the system level, Wilkins said.
Update: Plastic-GaAs spintronic device revealed
Ohio State University researchers have combined traditional inorganic semiconductors with organic spintronics, in a device claimed to be the first of its kind.
For the demonstration, the scientists used an organic magnet made from vanadium tetracyanoethylene, a polymer developed by Professor Arthur Epstein at Ohio State with Professor Joel Miller of the University of Utah - a material in which spintronic data storage and retrieval was achieved last year.
Now an Ohio State team led by Dr Ezekiel Johnston-Halperin has incorporated the polymer into a GaAs device.
"In order to build a practical spintronic device, you need a material that is both semiconducting and magnetic at room temperature. To my knowledge, Art's organic materials are the only ones that do that," said Johnston-Halperin.
"The polymer is a ferromagnet, and a massively interesting thing on its own. Even without a magnetic field, the polymer is still magnetic - just like iron or cobalt," he told Electronics Weekly.
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The experimental device is essentially an LED whose current has to flow through the polymer.
It exploits 'spin orbit coupling' where the spin of an electron creating a photon in GaAs or other direct bandgap semiconductor is transferred to the angular momentum of the photon, which is seen at right or left circular polarisation.
"The spintronics and interesting physics occurs between polymer and top, n-doped, layer," said Johnston-Halperin. "The only purpose of LED is to detect spin injection. It could be replaced with a transistor or other kind of electronic device, but with other devices, it is not very easy to tell whether spin-injection is happening."
Light leaving the LED is indeed polarised - indicating that spintronic action is occurring - and the direction of polarisation shows that electrons with spin that makes their magnetisation parallel to the polymer's own magnetic moment experience lower electrical resistance in the polymer than electrons magnetised at anti-parallel.
Essentially electrons with a certain spin state pass through preferentially.
Baulked electrons pass through later after their spin state flips spontaneously.
"The fact that they were able to measure the electrons' polarisation with the LED also suggests that other researchers can use this same technique to test spin in other organic systems," added Ohio State University.
Johnston-Halperin built the device as a science experiment: to examine the fundamental spin physics of the polymer, using the well-understood science of spin orbit coupling in GaAs as a tool to get quantative results.
"From a technology angle, it opens the door for hybrid material systems where you can play with the polymer or the GaAs," he said. "Hybrid structures promise functionality that no other materials, neither organic nor inorganic, can currently achieve alone."
The polymer cannot stand high temperatures or lithography solvents, so fabrication involved building the GaAs part in a conventional fab, then adding the organic layer at lower temperature, followed by deposition of the aluminium and gold contacts through a shadow mask to avoid etching.
"You could ask, why didn't we go with all organics, then?" asked Johnston-Halperin. "Well, the reality is that industry already knows how to make devices out of inorganic materials. That expertise and equipment is already in place. If we can just get organic and inorganic materials to work together, then we can take advantage of that existing infrastructure to move spintronics forward right away."
For the demonstration, the scientists used an organic magnet made from vanadium tetracyanoethylene, a polymer developed by Professor Arthur Epstein at Ohio State with Professor Joel Miller of the University of Utah - a material in which spintronic data storage and retrieval was achieved last year.
Now an Ohio State team led by Dr Ezekiel Johnston-Halperin has incorporated the polymer into a GaAs device.
"In order to build a practical spintronic device, you need a material that is both semiconducting and magnetic at room temperature. To my knowledge, Art's organic materials are the only ones that do that," said Johnston-Halperin.
"The polymer is a ferromagnet, and a massively interesting thing on its own. Even without a magnetic field, the polymer is still magnetic - just like iron or cobalt," he told Electronics Weekly.
Advertisement
The experimental device is essentially an LED whose current has to flow through the polymer.
It exploits 'spin orbit coupling' where the spin of an electron creating a photon in GaAs or other direct bandgap semiconductor is transferred to the angular momentum of the photon, which is seen at right or left circular polarisation.
"The spintronics and interesting physics occurs between polymer and top, n-doped, layer," said Johnston-Halperin. "The only purpose of LED is to detect spin injection. It could be replaced with a transistor or other kind of electronic device, but with other devices, it is not very easy to tell whether spin-injection is happening."
Light leaving the LED is indeed polarised - indicating that spintronic action is occurring - and the direction of polarisation shows that electrons with spin that makes their magnetisation parallel to the polymer's own magnetic moment experience lower electrical resistance in the polymer than electrons magnetised at anti-parallel.
Essentially electrons with a certain spin state pass through preferentially.
Baulked electrons pass through later after their spin state flips spontaneously.
"The fact that they were able to measure the electrons' polarisation with the LED also suggests that other researchers can use this same technique to test spin in other organic systems," added Ohio State University.
Johnston-Halperin built the device as a science experiment: to examine the fundamental spin physics of the polymer, using the well-understood science of spin orbit coupling in GaAs as a tool to get quantative results.
"From a technology angle, it opens the door for hybrid material systems where you can play with the polymer or the GaAs," he said. "Hybrid structures promise functionality that no other materials, neither organic nor inorganic, can currently achieve alone."
The polymer cannot stand high temperatures or lithography solvents, so fabrication involved building the GaAs part in a conventional fab, then adding the organic layer at lower temperature, followed by deposition of the aluminium and gold contacts through a shadow mask to avoid etching.
"You could ask, why didn't we go with all organics, then?" asked Johnston-Halperin. "Well, the reality is that industry already knows how to make devices out of inorganic materials. That expertise and equipment is already in place. If we can just get organic and inorganic materials to work together, then we can take advantage of that existing infrastructure to move spintronics forward right away."
2011年5月8日星期日
Intel finds higher speed in new dimension
The transistors on computer chips – whether for PCs or smartphones – have been designed in essentially the same way since 1959 when Intel co-founder Robert Noyce and Texas Instruments’ Jack Kilby independently invented the first integrated circuits that became the basic building block of electronic devices in the information age.
These early chips were built on a flat surface. But like a real estate developer building skyscrapers to get more rentable space from a plot of land, Intel is now building up. When the space between the billions of tiny electronic switches on the flat surface of a computer chip is measured in the width of just dozens of atoms, designers needed the third dimension to find more room.
The company has already begun making its microprocessors using a new 3D transistor design, called a Finfet (for fin field-effect transistor), which is based around a remarkably small pillar, or fin, of silicon that rises above the surface of the chip. Santa Clara, California-based Intel plans to enter general production based on the new technology some time later this year.
Although the company did not give technical details about its new process, it said that it expected to be able to make chips that run as much as 37 percent faster in low-voltage applications and it would be able to cut power consumption as much as 50 per cent. Intel currently uses a photolithographic process to make a chip, in which the smallest feature on the chip is just 32 nanometres, a level of microscopic manufacture that was reached in 2009. (By comparison a human red blood cell is 7,500 nanometres in width and a strand of DNA is 2.5 nanometres.) “Intel is on track for 22-nanometer manufacturing later this year,” said Intel senior fellow and scientist Mark T Bohr, who has overseen the effort to develop the next generation of smaller transistors.
The company’s engineers said that they now felt confident that they would be able to solve the challenges of making chips through at least the 10-nanometre generation, which is likely to happen in 2015.
The timing of the announcement is significant, Bohr said, because it is evidence that the world’s largest chip-maker is not slipping from the pace of doubling the number of transistors that can be etched onto a sliver of silicon every two years, a phenomenon known as Moore’s Law.
Although not a law of physics, the 1965 observation by Intel co-founder Gordon Moore, has defined the speed of innovation for much of the world’s economy. It has also set the computing industry apart from other types of manufacturing because it has continued to improve at an accelerating rate, offering greater computing power and lower cost at regular intervals.
However, despite its promise and the company’s bold claims, Intel’s 3D transistor is still a controversial technology within the chip industry. Indeed, a number of the company’s competitors say they believe that Intel is taking what could be a disastrous multibillion-dollar gamble on an unproved technology. There has been industry speculation that Finfet technology will give Intel a clear speed advantage, but possibly less control over power consumption than alternative approaches. By opting for a technology that emphasises speed over low power, Intel faces the possibility that it could win the technology battle and yet lose the more important battle in the marketplace.
The scope of Intel’s gamble is underscored by the fact that while the company dominates in the markets for data centre computers, desktops and laptops, it has largely been locked out of the tablet and smartphone markets, which are growing far more quickly than the traditional PC industry. Those devices use ultra-low-powered chips to conserve battery power and reduce overheating.
Apple, for example, uses Intel microprocessors for its desktops and laptops, but for the iPhone and iPad it has chosen to use a rival low-power design, built by others, that Apple originally helped pioneer in the late 1980s.
Industry executives and analysts have said that Intel is likely to have a lead of a full generation over its rivals in the shift to 3D transistors. For example, taiwan-based chip-maker TSMC has said that it does not plan to deploy Finfet transistor technology for another two years.
Other companies, like ST Microelectronics, are wagering that an alternative technology based on placing a remarkably thin insulating layer below traditional transistors will chart a safer course toward the next generation of chip manufacturing. They believe that the insulation approach will excel in low-power applications, and that could be a crucial advantage in consumer-oriented markets where a vast majority of popular products are both hand-held and battery-powered.
“Silicon-on-insulator could be a win in terms of power efficiency,” Semiconductor Manufacturing and Design Community website editor-in-chief David Lammers said. “From what I am hearing from the SOI camp, there is a consensus and concession that Finfets are faster. That’s the way you want to go for leading-edge performance.”
In a factory tour here last week, Intel used a scanning electronic microscope to display a computer chip made using the new 22-nanometre manufacturing process. Viewed at a magnification of more than 1,00,000 times, the silicon fins are clearly visible as a series of walls projected above a flat surface. It is possible to make transistors out of one or a number of the tiny fins to build switches that have different characteristics, such as faster switching speeds or extremely low power. Looking at the chip under less magnification, it is possible to see the wiring design, which appears much like a street map displaying millions of intersections.
Despite the impressive display, Intel’s executives acknowledge the challenge the company is facing in trying to catch up in the new consumer markets that so far have eluded it.
“The ecosystem right now is not aligned in our favor,” said Intel chief administrative officer Andy D Bryant, who now runs the company’s technology and manufacturing group. “It has to be good enough for the ecosystem to take notice and say, ‘We better pay attention to those guys.”
These early chips were built on a flat surface. But like a real estate developer building skyscrapers to get more rentable space from a plot of land, Intel is now building up. When the space between the billions of tiny electronic switches on the flat surface of a computer chip is measured in the width of just dozens of atoms, designers needed the third dimension to find more room.
The company has already begun making its microprocessors using a new 3D transistor design, called a Finfet (for fin field-effect transistor), which is based around a remarkably small pillar, or fin, of silicon that rises above the surface of the chip. Santa Clara, California-based Intel plans to enter general production based on the new technology some time later this year.
Although the company did not give technical details about its new process, it said that it expected to be able to make chips that run as much as 37 percent faster in low-voltage applications and it would be able to cut power consumption as much as 50 per cent. Intel currently uses a photolithographic process to make a chip, in which the smallest feature on the chip is just 32 nanometres, a level of microscopic manufacture that was reached in 2009. (By comparison a human red blood cell is 7,500 nanometres in width and a strand of DNA is 2.5 nanometres.) “Intel is on track for 22-nanometer manufacturing later this year,” said Intel senior fellow and scientist Mark T Bohr, who has overseen the effort to develop the next generation of smaller transistors.
The company’s engineers said that they now felt confident that they would be able to solve the challenges of making chips through at least the 10-nanometre generation, which is likely to happen in 2015.
The timing of the announcement is significant, Bohr said, because it is evidence that the world’s largest chip-maker is not slipping from the pace of doubling the number of transistors that can be etched onto a sliver of silicon every two years, a phenomenon known as Moore’s Law.
Although not a law of physics, the 1965 observation by Intel co-founder Gordon Moore, has defined the speed of innovation for much of the world’s economy. It has also set the computing industry apart from other types of manufacturing because it has continued to improve at an accelerating rate, offering greater computing power and lower cost at regular intervals.
However, despite its promise and the company’s bold claims, Intel’s 3D transistor is still a controversial technology within the chip industry. Indeed, a number of the company’s competitors say they believe that Intel is taking what could be a disastrous multibillion-dollar gamble on an unproved technology. There has been industry speculation that Finfet technology will give Intel a clear speed advantage, but possibly less control over power consumption than alternative approaches. By opting for a technology that emphasises speed over low power, Intel faces the possibility that it could win the technology battle and yet lose the more important battle in the marketplace.
The scope of Intel’s gamble is underscored by the fact that while the company dominates in the markets for data centre computers, desktops and laptops, it has largely been locked out of the tablet and smartphone markets, which are growing far more quickly than the traditional PC industry. Those devices use ultra-low-powered chips to conserve battery power and reduce overheating.
Apple, for example, uses Intel microprocessors for its desktops and laptops, but for the iPhone and iPad it has chosen to use a rival low-power design, built by others, that Apple originally helped pioneer in the late 1980s.
Industry executives and analysts have said that Intel is likely to have a lead of a full generation over its rivals in the shift to 3D transistors. For example, taiwan-based chip-maker TSMC has said that it does not plan to deploy Finfet transistor technology for another two years.
Other companies, like ST Microelectronics, are wagering that an alternative technology based on placing a remarkably thin insulating layer below traditional transistors will chart a safer course toward the next generation of chip manufacturing. They believe that the insulation approach will excel in low-power applications, and that could be a crucial advantage in consumer-oriented markets where a vast majority of popular products are both hand-held and battery-powered.
“Silicon-on-insulator could be a win in terms of power efficiency,” Semiconductor Manufacturing and Design Community website editor-in-chief David Lammers said. “From what I am hearing from the SOI camp, there is a consensus and concession that Finfets are faster. That’s the way you want to go for leading-edge performance.”
In a factory tour here last week, Intel used a scanning electronic microscope to display a computer chip made using the new 22-nanometre manufacturing process. Viewed at a magnification of more than 1,00,000 times, the silicon fins are clearly visible as a series of walls projected above a flat surface. It is possible to make transistors out of one or a number of the tiny fins to build switches that have different characteristics, such as faster switching speeds or extremely low power. Looking at the chip under less magnification, it is possible to see the wiring design, which appears much like a street map displaying millions of intersections.
Despite the impressive display, Intel’s executives acknowledge the challenge the company is facing in trying to catch up in the new consumer markets that so far have eluded it.
“The ecosystem right now is not aligned in our favor,” said Intel chief administrative officer Andy D Bryant, who now runs the company’s technology and manufacturing group. “It has to be good enough for the ecosystem to take notice and say, ‘We better pay attention to those guys.”
Asbestos incident at Surry plant probed
The state Department of Labor and Industry is investigating a claim of asbestos exposure at Surry Power Station.
The claim was made by a contractor working with the station's owner, Dominion Virginia Power, to refuel one of two nuclear reactors.
It was made some time — neither Dominion nor state officials would say when — after April 16, when a tornado knocked out power to the station. Backup generators kicked on to prevent the release of harmful radiation.
"We're looking into it, yes," said department spokeswoman Jennifer Wester, who declined to elaborate pending results of the investigation.
Hundreds of contractors from multiple companies have been working at the station to refuel the reactor, a process that usually takes a month. Some are replacing turbines, which are kept in a building separate from the reactors, Dominion spokesman Rick Zuercher said.
Dominion suspended work after a contractor complained the area might not be safe. Zuercher said a "team of experts" determined that asbestos levels did not exceed standards set by the Occupational Safety and Health Administration.
Work has since resumed, he said.
Asbestos was commonly used as an insulator and fire retardant in building materials and heat-resistant gaskets and coatings, according to the U.S. Environmental Protection Agency.
Left alone, it usually does not harm humans. But when disturbed, microscopic fibers can enter the lungs and, after continuous exposure, can cause lung cancer, asbestosis and mesothelioma.
Most products that contained asbestos were banned and phased out of usage in the 1990s, according to the EPA.
The claim was made by a contractor working with the station's owner, Dominion Virginia Power, to refuel one of two nuclear reactors.
It was made some time — neither Dominion nor state officials would say when — after April 16, when a tornado knocked out power to the station. Backup generators kicked on to prevent the release of harmful radiation.
"We're looking into it, yes," said department spokeswoman Jennifer Wester, who declined to elaborate pending results of the investigation.
Hundreds of contractors from multiple companies have been working at the station to refuel the reactor, a process that usually takes a month. Some are replacing turbines, which are kept in a building separate from the reactors, Dominion spokesman Rick Zuercher said.
Dominion suspended work after a contractor complained the area might not be safe. Zuercher said a "team of experts" determined that asbestos levels did not exceed standards set by the Occupational Safety and Health Administration.
Work has since resumed, he said.
Asbestos was commonly used as an insulator and fire retardant in building materials and heat-resistant gaskets and coatings, according to the U.S. Environmental Protection Agency.
Left alone, it usually does not harm humans. But when disturbed, microscopic fibers can enter the lungs and, after continuous exposure, can cause lung cancer, asbestosis and mesothelioma.
Most products that contained asbestos were banned and phased out of usage in the 1990s, according to the EPA.
2011年5月5日星期四
How to build a fence
DONE properly, fencing is one of the farm's most valuable assets.
I believe regular fence building and maintenance is an excellent investment in time and money.
I have even discovered a ratio on my farm: each hour of completed fencing saves about three hours of mustering-drafting of strayed stock later on.
Every paddock I subdivide into two doubles my productivity through better grazing management, easier tree establishment and being able to run the farm as one profitable labour unit.
The cost of sheep and cattle-proof fencing built by a contractor is about $7 a metre, with roughly half being labour costs and the other half material costs.
This can be expensive, so the key is to do much of the work yourself and try to obtain fencing materials at minimal costs.
The availability of light pine posts and star picket steel posts, modern plain wire and prefabricated hingejoint or ringlock (a type of mesh fencing) makes the job a pleasure compared to the materials we used years ago.
If you are entirely new to the job, consider enlisting the help of an expert or leaving the whole job to a professional fencer while you make money elsewhere.
But if you are intent to keep your farm profitable and invest the savings in better genetics, pastures or fertilisers, you should consider obtaining materials on the cheap through recycling.
The materials should be gathered over the year and every year - if you store fencing material long enough you will eventually use it.
Annual storms will bring down mature yellow and grey box trees which can be cut into two-metre length strainers and three-metre length stays. This great timber can last up to 60 years as posts. Ignore the fast growing gums such as candlebark or peppermint-messmate as they will rot away before 10 years is out.
Clearing sales, garage sales and other farmers who are renewing their fences often sell steel posts and pine posts at as little as $1 each. I have secured several hundred this way and now have so many I can follow my passion of using the extras as tree stakes to forest my farm in shade and shelter.
Many older farm gates and rolls of hingejoint are thrown out or discarded beside the new fence and are there for the asking. I get enough free fencing material to do a kilometre every year and the cost is only my time.
GETTING STARTED
AN EFFECTIVE fence for sheep, cattle, horses or goats can be made using 150mm diameter pine posts rammed in at 15m intervals with two steel posts in between - all at 120cm heights. Hingejoint of 8/90/30 (eight wires spanning 90cm with 30cm rectangles) is attached with a high-tensile, 2.5 mm plain wire on the top.
High-tensile wires retain their tightness.
For cattle or horses, finish off with an electric wire set on offset brackets and a porcelain insulator. As hungry cattle and horses see fences as a pushover for a morsel of grass on the other side, as well as scratch poles, always electrify a new fence three quarters of the way up if you wish the fence to last more than a year.
Electric fencing for sheep is not the success it is for cattle. If you can't electrify and you still want to run cattle and not horses, two barbs on top, spaced by one plain wire, works well.
Hingejoint or ringlock is a must for sheep or goats as they can't fit through the rectangles. It works well when stock-proofing an existing plain wire fence even if it is not strained tightly. However it can be substituted for six or seven plain wires for cattle.
A fence strain should be no shorter than 100m and no longer than 200m to maintain tightness. Short fences of 20m will always have loose wires, so a top pine rail, placed along the entire length with turnbuckles or ratchet-like permanent end strainers for occasional manual tightening, is a good remedy.
Riverina mesh (110cm high) is excellent in small paddocks and yards as lambs cannot get through nor concuss themselves by ramming it.
I believe regular fence building and maintenance is an excellent investment in time and money.
I have even discovered a ratio on my farm: each hour of completed fencing saves about three hours of mustering-drafting of strayed stock later on.
Every paddock I subdivide into two doubles my productivity through better grazing management, easier tree establishment and being able to run the farm as one profitable labour unit.
The cost of sheep and cattle-proof fencing built by a contractor is about $7 a metre, with roughly half being labour costs and the other half material costs.
This can be expensive, so the key is to do much of the work yourself and try to obtain fencing materials at minimal costs.
The availability of light pine posts and star picket steel posts, modern plain wire and prefabricated hingejoint or ringlock (a type of mesh fencing) makes the job a pleasure compared to the materials we used years ago.
If you are entirely new to the job, consider enlisting the help of an expert or leaving the whole job to a professional fencer while you make money elsewhere.
But if you are intent to keep your farm profitable and invest the savings in better genetics, pastures or fertilisers, you should consider obtaining materials on the cheap through recycling.
The materials should be gathered over the year and every year - if you store fencing material long enough you will eventually use it.
Annual storms will bring down mature yellow and grey box trees which can be cut into two-metre length strainers and three-metre length stays. This great timber can last up to 60 years as posts. Ignore the fast growing gums such as candlebark or peppermint-messmate as they will rot away before 10 years is out.
Clearing sales, garage sales and other farmers who are renewing their fences often sell steel posts and pine posts at as little as $1 each. I have secured several hundred this way and now have so many I can follow my passion of using the extras as tree stakes to forest my farm in shade and shelter.
Many older farm gates and rolls of hingejoint are thrown out or discarded beside the new fence and are there for the asking. I get enough free fencing material to do a kilometre every year and the cost is only my time.
GETTING STARTED
AN EFFECTIVE fence for sheep, cattle, horses or goats can be made using 150mm diameter pine posts rammed in at 15m intervals with two steel posts in between - all at 120cm heights. Hingejoint of 8/90/30 (eight wires spanning 90cm with 30cm rectangles) is attached with a high-tensile, 2.5 mm plain wire on the top.
High-tensile wires retain their tightness.
For cattle or horses, finish off with an electric wire set on offset brackets and a porcelain insulator. As hungry cattle and horses see fences as a pushover for a morsel of grass on the other side, as well as scratch poles, always electrify a new fence three quarters of the way up if you wish the fence to last more than a year.
Electric fencing for sheep is not the success it is for cattle. If you can't electrify and you still want to run cattle and not horses, two barbs on top, spaced by one plain wire, works well.
Hingejoint or ringlock is a must for sheep or goats as they can't fit through the rectangles. It works well when stock-proofing an existing plain wire fence even if it is not strained tightly. However it can be substituted for six or seven plain wires for cattle.
A fence strain should be no shorter than 100m and no longer than 200m to maintain tightness. Short fences of 20m will always have loose wires, so a top pine rail, placed along the entire length with turnbuckles or ratchet-like permanent end strainers for occasional manual tightening, is a good remedy.
Riverina mesh (110cm high) is excellent in small paddocks and yards as lambs cannot get through nor concuss themselves by ramming it.
Wailuku Power Outage Affects 2,000
An estimated 2,000 Maui Electric Company customers in Wailuku had power restored at around 11 o’clock this morning. The outage was first reported at around 9:20 a.m. and affected customers on Waiehu Beach Road, Eha Street, Lower Main Street, Hookahi and Waena Street.
At last report an estimated 15 customers on Momi Lane remained without power.
MECO crews continued work to repair a downed line and estimated that power would be restored within an hour. The cause of the outage was a failed insulator.
Crews from Maui Electric Company are investigating a power outage that knocked out electricity to some 2,000 customers in Wailuku this morning.
At about 9:20 a.m. a power outage occurred affecting parts of Wailuku including Lower Main Street, Waiehu Beach Road, Eha Street, Hookahi Street, Waena Street and lateral areas.
The cause of the outage is currently under investigation. MECO officials will provide us with an update as soon as more information becomes available.
At last report an estimated 15 customers on Momi Lane remained without power.
MECO crews continued work to repair a downed line and estimated that power would be restored within an hour. The cause of the outage was a failed insulator.
Crews from Maui Electric Company are investigating a power outage that knocked out electricity to some 2,000 customers in Wailuku this morning.
At about 9:20 a.m. a power outage occurred affecting parts of Wailuku including Lower Main Street, Waiehu Beach Road, Eha Street, Hookahi Street, Waena Street and lateral areas.
The cause of the outage is currently under investigation. MECO officials will provide us with an update as soon as more information becomes available.
Transistors go 3D as Intel re-invents the microchip
At an event today in San Francisco, Intel announced one of the most important pieces of semiconductor news in many years: the company's upcoming 22nm processors will feature a fundamental change to the design of the most basic building block of every computer chip, the transistor.
Intel has been exploring the new transistor for over a decade, and the company first announced a significant breakthrough with the design in 2002. A trickle of announcements followed over the years, as the new transistor progressed from being one possible direction among many to its newly crowned status as the official future of Intel's entire product line.
In this short article, I'll give my best stab at explaining what Intel has announced—the so-called tri-gate transistor. Semiconductor physics are not my strong suit, so corrections/clarifications/comments are welcome. Also, this explanation focuses solely on the "3D" part of today's announcements. Other features of the 22nm process, like high-K dielectrics and such, are ignored. (So if you see a funny term on a slide and you don't know what it means, either ignore it or hit one of the Related Links for more info.)
But before we dive into what's new about Intel's transistor design, we first have to review how traditional transistors work.
In the diagram above, you can see that a traditional "planar" transistor—the kind that was first invented at the dawn of the microchip era, and which has been the norm up until today's announcement—consists of three main parts: source, drain, and gate. (This is actually one specific kind of transistor, a MOSFET, but let's not get too deep into the weeds.)
The device may look odd, but it's really just an electrical switch. Think of the source and the drain as the two slots in a standard electrical socket; if you stuck a conducting wire (like a coat-hanger ) into both of the slots, you'd close the circuit and current would flow (and sparks would fly, flesh would burn, etc... so don't try that at home.) The transistor's substrate is sort of like a magic wire that can either conduct electricity or not, and the gate is the switch that controls whether the wire will conduct or not.
So when a voltage is applied to the metal plate that forms the transistor's gate, a tiny strip of semiconductor material between the source and the drain (our magic wire) changes from an insulator into a conductor, thereby turning the switch "on" and allowing current to flow from the source to the drain. When the voltage is removed, current stops flowing... or, at least, current is supposed to stop flowing when the switch is off. In reality, trace amounts of current will constantly flow between the source and the drain. This so-called "leakage current" wastes precious power and becomes even more of a problem as transistors get smaller and more numerous.
So to recap, the basic idea is that the transistor is a switch that works because a tiny bit of insulating material between two "electrodes" magically morphs into a conductor when a voltage is applied to it, thereby closing the circuit.
Intel has been exploring the new transistor for over a decade, and the company first announced a significant breakthrough with the design in 2002. A trickle of announcements followed over the years, as the new transistor progressed from being one possible direction among many to its newly crowned status as the official future of Intel's entire product line.
In this short article, I'll give my best stab at explaining what Intel has announced—the so-called tri-gate transistor. Semiconductor physics are not my strong suit, so corrections/clarifications/comments are welcome. Also, this explanation focuses solely on the "3D" part of today's announcements. Other features of the 22nm process, like high-K dielectrics and such, are ignored. (So if you see a funny term on a slide and you don't know what it means, either ignore it or hit one of the Related Links for more info.)
But before we dive into what's new about Intel's transistor design, we first have to review how traditional transistors work.
In the diagram above, you can see that a traditional "planar" transistor—the kind that was first invented at the dawn of the microchip era, and which has been the norm up until today's announcement—consists of three main parts: source, drain, and gate. (This is actually one specific kind of transistor, a MOSFET, but let's not get too deep into the weeds.)
The device may look odd, but it's really just an electrical switch. Think of the source and the drain as the two slots in a standard electrical socket; if you stuck a conducting wire (like a coat-hanger ) into both of the slots, you'd close the circuit and current would flow (and sparks would fly, flesh would burn, etc... so don't try that at home.) The transistor's substrate is sort of like a magic wire that can either conduct electricity or not, and the gate is the switch that controls whether the wire will conduct or not.
So when a voltage is applied to the metal plate that forms the transistor's gate, a tiny strip of semiconductor material between the source and the drain (our magic wire) changes from an insulator into a conductor, thereby turning the switch "on" and allowing current to flow from the source to the drain. When the voltage is removed, current stops flowing... or, at least, current is supposed to stop flowing when the switch is off. In reality, trace amounts of current will constantly flow between the source and the drain. This so-called "leakage current" wastes precious power and becomes even more of a problem as transistors get smaller and more numerous.
So to recap, the basic idea is that the transistor is a switch that works because a tiny bit of insulating material between two "electrodes" magically morphs into a conductor when a voltage is applied to it, thereby closing the circuit.
2011年5月2日星期一
The theory of Wan et al
Topology, the mathematical description of the robustness of form, appears throughout physics, and provides strong constraints on many physical systems. It has long been known that it plays a key role in understanding the exotic phenomena of the quantum Hall effect. Recently, it has been found to generate robust and interesting bulk and surface phenomena in “ordinary” band insulators described by the old Bloch theory of solids. Such “topological insulators,” insulating in the bulk and metallic on the surface, occur in the presence of strong spin-orbit coupling in certain crystals, with unbroken time-reversal symmetry [1].
It is usually believed that such topological physics is obliterated in materials where magnetic ordering breaks time-reversal symmetry. This is by far the most common fate for transition-metal compounds that manage to be insulators—so called “Mott insulators,” which owe their lack of conduction to the strong Coulomb repulsion between electrons. In an article appearing in Physical Review B, Xiangang Wan from Nanjing University, China, and collaborators from the University of California and the Lawrence Berkeley National Laboratory, US, show that this is not necessarily the case, and describe a remarkable electronic structure with topological aspects that is unique to such (antiferro-)magnetic materials [2]. The state they describe is remarkable in possessing interesting low-energy electron states in the bulk and at the surface, linked by topology. In contrast, topological insulators, like quantum Hall states, possess low-energy electronic states only at the surface.
The theory of Wan et al., which uses the LDA+U numerical method, is a type of mean field theory. As such, the low-energy quasiparticle excitations are described simply by noninteracting electrons in a background electrostatic potential and, in the case of a magnetically ordered phase, by a spatially periodic exchange field. It is possible to follow the evolution of the electronic states as a function of the U parameter, which is used to model the strength of Coulomb correlations. They apply the technique to iridium pyrochlores, R2Ir2O7, where R is a rare earth element. These materials are known to exhibit metal-insulator transitions (see, e.g., Ref. [3]), indicating substantial correlations, and are characterized by strong spin-orbit coupling due to the heavy element Ir (iridium). In the intermediate range of U, which they suggest is relevant for these compounds, Wan et al. find an antiferromagnetic ground state with the band structure of a “zero-gap semimetal,” in which the conduction and valence bands “kiss” at a discrete number (24!) of momenta. The dispersion of the bands approaching each touching point is linear, reminiscent of massless Dirac fermions such as those observed in graphene.
This would be interesting in itself, but there are important differences from graphene. Because of the antiferromagnetism, time-reversal symmetry is broken, and as a consequence, despite the centrosymmetric nature of the crystals in question, the bands are nondegenerate. Thus two—and only two—states are degenerate at each touching point, unlike in graphene where there are four. In fact, the kissing bands found by Wan et al. are an example of accidental degeneracy in quantum mechanics, a subject discussed in the early days of quantum theory by von Neumann and Wigner (1929), and applied to band theory by Herring (1937). The phenomenon of level repulsion in quantum mechanics tends to prevent such band crossings. To force two levels to be degenerate, one must consider the 2×2 Hamiltonian matrix projected into this subspace: not only must the two diagonal elements be made equal, the two off-diagonal elements must be made to vanish. This requires three real parameters to be tuned to achieve degeneracy. Thus, without additional symmetry constraints, such accidental degeneracies are vanishingly improbable in one and two dimensions, but can occur as isolated points in momentum space in three dimensions (the three components of the momentum serving as tuning parameters). An accidental touching of this type is called a diabolical point. The 2×2 matrix Schrödinger equation in the vicinity of this point is mathematically similar to a two-component Dirac-like one, known as the Weyl equation. Thus the low-energy electrons in this state behave like Weyl fermions. A property of such a diabolical point is that it cannot be removed by any small perturbation, but may only disappear by annihilation with another diabolical point.
It is usually believed that such topological physics is obliterated in materials where magnetic ordering breaks time-reversal symmetry. This is by far the most common fate for transition-metal compounds that manage to be insulators—so called “Mott insulators,” which owe their lack of conduction to the strong Coulomb repulsion between electrons. In an article appearing in Physical Review B, Xiangang Wan from Nanjing University, China, and collaborators from the University of California and the Lawrence Berkeley National Laboratory, US, show that this is not necessarily the case, and describe a remarkable electronic structure with topological aspects that is unique to such (antiferro-)magnetic materials [2]. The state they describe is remarkable in possessing interesting low-energy electron states in the bulk and at the surface, linked by topology. In contrast, topological insulators, like quantum Hall states, possess low-energy electronic states only at the surface.
The theory of Wan et al., which uses the LDA+U numerical method, is a type of mean field theory. As such, the low-energy quasiparticle excitations are described simply by noninteracting electrons in a background electrostatic potential and, in the case of a magnetically ordered phase, by a spatially periodic exchange field. It is possible to follow the evolution of the electronic states as a function of the U parameter, which is used to model the strength of Coulomb correlations. They apply the technique to iridium pyrochlores, R2Ir2O7, where R is a rare earth element. These materials are known to exhibit metal-insulator transitions (see, e.g., Ref. [3]), indicating substantial correlations, and are characterized by strong spin-orbit coupling due to the heavy element Ir (iridium). In the intermediate range of U, which they suggest is relevant for these compounds, Wan et al. find an antiferromagnetic ground state with the band structure of a “zero-gap semimetal,” in which the conduction and valence bands “kiss” at a discrete number (24!) of momenta. The dispersion of the bands approaching each touching point is linear, reminiscent of massless Dirac fermions such as those observed in graphene.
This would be interesting in itself, but there are important differences from graphene. Because of the antiferromagnetism, time-reversal symmetry is broken, and as a consequence, despite the centrosymmetric nature of the crystals in question, the bands are nondegenerate. Thus two—and only two—states are degenerate at each touching point, unlike in graphene where there are four. In fact, the kissing bands found by Wan et al. are an example of accidental degeneracy in quantum mechanics, a subject discussed in the early days of quantum theory by von Neumann and Wigner (1929), and applied to band theory by Herring (1937). The phenomenon of level repulsion in quantum mechanics tends to prevent such band crossings. To force two levels to be degenerate, one must consider the 2×2 Hamiltonian matrix projected into this subspace: not only must the two diagonal elements be made equal, the two off-diagonal elements must be made to vanish. This requires three real parameters to be tuned to achieve degeneracy. Thus, without additional symmetry constraints, such accidental degeneracies are vanishingly improbable in one and two dimensions, but can occur as isolated points in momentum space in three dimensions (the three components of the momentum serving as tuning parameters). An accidental touching of this type is called a diabolical point. The 2×2 matrix Schrödinger equation in the vicinity of this point is mathematically similar to a two-component Dirac-like one, known as the Weyl equation. Thus the low-energy electrons in this state behave like Weyl fermions. A property of such a diabolical point is that it cannot be removed by any small perturbation, but may only disappear by annihilation with another diabolical point.
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