Developing wireless nanodevices and nanosystems is of critical importance for sensing, medical science, environmental/infrastructure monitoring, defense technology and even personal electronics. It is highly desirable...Developing wireless nanodevices and nanosystems is of critical importance for sensing, medical science, environmental/infrastructure monitoring, defense technology and even personal electronics. It is highly desirable for wireless devices to be self-powered without using battery, without which most of the sensor network may be impossible. The pie- zoelectric nanogenerators have the potential to serve as self-sufficient power sources for micro/nano systems. For wurtzite structures that have non-central symmetry, such as ZnO, GaN and InN, a piezoelectric potential （piezopotential） is created in the crystal by applying a strain. The nanogenerator is invented by using the piezopotential as the driving force for electrons to flow in respond to a dynamic straining of piezoelectric nanowires. A gentle straining can produce an output voltage of up to 20 - 50 V from an integrated nanogenerator. Furthermore, piezopotential in the wurtzite structure can serve as gate voltage that can effectively tune/control the charge transport across an interface/junction; electronics fabricated based on such a mechanism is coined as piezotronics, with applications in force/pressure triggercd/controlled electronic devices, sensors, logic units and memory. By using the piezotronic effect, it is showed that the optoelectronic devices fabricated using wurtzite materials can have superior performance as solar cell, photon detector and light emitting diode. Piezotronie is likely to serve as ＂mechanosensation＂ for directly interfacing biomechanieal action with silicon based technology and active flexible electronics. The paper gives a brief review about the basis of nanogenertors and piezotronics and their potential applications in smart MEMS （micro-electro-mechanical systems）.展开更多
In order to realize on-line quantitative detection on SF6 and effective control of nlnning state of SF6 high voltage power supply system, a concentrated SF6 quantitative ultrasonic on-line deteetion system has been de...In order to realize on-line quantitative detection on SF6 and effective control of nlnning state of SF6 high voltage power supply system, a concentrated SF6 quantitative ultrasonic on-line deteetion system has been developed based on the actual demand of electric power system consumers. There are four major characteristics in this system. Firstly, the gas of maximum 64 detection points is transferred through the specific air path to the detection devices to he detected and analyzed, thereby the electrical lines and the complicated installation of the collectors can be avoided; secondly, the differential technique is used to shield the influence of environmental factors, which effectively improves the accuracy of the acoustic detection; thirdly, the SF6 coneentration is determined by the speed and phase in the ultrasonic wave trans- mission process, therefore there is no secondary pollution for the purely physical means; finally, the ma- ture embedded technique is applied in this system to improve its intelligence and stability.展开更多
The main equipmets of the HL-2A LHCD power supply are based on the old one, but the logical control protective system is a new part. Considering the output voltage is very high（up to 60 kV）, so the logical control p...The main equipmets of the HL-2A LHCD power supply are based on the old one, but the logical control protective system is a new part. Considering the output voltage is very high（up to 60 kV）, so the logical control protective system is very important. The system is implemented based on PLC and the SIEMENS STEP7 software.展开更多
The quality of supply in Spain is regulated by Act 54/1997 as the basic standard and further developed by Royal Decree 1955/2000, among others. Also this law （1997） introduces the division between generators, distri...The quality of supply in Spain is regulated by Act 54/1997 as the basic standard and further developed by Royal Decree 1955/2000, among others. Also this law （1997） introduces the division between generators, distribution companies and retailers. The aim of this paper is to provide an overview of the fundamental parameters to be taken into account when examining the status of national regulations in Spain on the quality of electricity supply, in addition to describing the various agents intervening in these. There are two more aspects to consider： the guarantee of supply and energy is provided at the lowest cost to consumers. The authors propose to include phase-shifting transformers at specific strategic points, in accordance with power flow control principles in parallel circuits. Finally, it can be concluded that Royal Decree 222/2008 needs reviewing and applying effectively, as do modifications to Royal Decree 1995/2000 providing remuneration that effectively induces electricity companies to invest in their networks, and ends with ＂a well-paid electricity company is obliged to invest in network improvements＂.展开更多
文摘Developing wireless nanodevices and nanosystems is of critical importance for sensing, medical science, environmental/infrastructure monitoring, defense technology and even personal electronics. It is highly desirable for wireless devices to be self-powered without using battery, without which most of the sensor network may be impossible. The pie- zoelectric nanogenerators have the potential to serve as self-sufficient power sources for micro/nano systems. For wurtzite structures that have non-central symmetry, such as ZnO, GaN and InN, a piezoelectric potential （piezopotential） is created in the crystal by applying a strain. The nanogenerator is invented by using the piezopotential as the driving force for electrons to flow in respond to a dynamic straining of piezoelectric nanowires. A gentle straining can produce an output voltage of up to 20 - 50 V from an integrated nanogenerator. Furthermore, piezopotential in the wurtzite structure can serve as gate voltage that can effectively tune/control the charge transport across an interface/junction; electronics fabricated based on such a mechanism is coined as piezotronics, with applications in force/pressure triggercd/controlled electronic devices, sensors, logic units and memory. By using the piezotronic effect, it is showed that the optoelectronic devices fabricated using wurtzite materials can have superior performance as solar cell, photon detector and light emitting diode. Piezotronie is likely to serve as ＂mechanosensation＂ for directly interfacing biomechanieal action with silicon based technology and active flexible electronics. The paper gives a brief review about the basis of nanogenertors and piezotronics and their potential applications in smart MEMS （micro-electro-mechanical systems）.
基金Supported by the National Natural Science Foundation of China (No. 10574038)
文摘In order to realize on-line quantitative detection on SF6 and effective control of nlnning state of SF6 high voltage power supply system, a concentrated SF6 quantitative ultrasonic on-line deteetion system has been developed based on the actual demand of electric power system consumers. There are four major characteristics in this system. Firstly, the gas of maximum 64 detection points is transferred through the specific air path to the detection devices to he detected and analyzed, thereby the electrical lines and the complicated installation of the collectors can be avoided; secondly, the differential technique is used to shield the influence of environmental factors, which effectively improves the accuracy of the acoustic detection; thirdly, the SF6 coneentration is determined by the speed and phase in the ultrasonic wave trans- mission process, therefore there is no secondary pollution for the purely physical means; finally, the ma- ture embedded technique is applied in this system to improve its intelligence and stability.
文摘The main equipmets of the HL-2A LHCD power supply are based on the old one, but the logical control protective system is a new part. Considering the output voltage is very high（up to 60 kV）, so the logical control protective system is very important. The system is implemented based on PLC and the SIEMENS STEP7 software.
文摘The quality of supply in Spain is regulated by Act 54/1997 as the basic standard and further developed by Royal Decree 1955/2000, among others. Also this law （1997） introduces the division between generators, distribution companies and retailers. The aim of this paper is to provide an overview of the fundamental parameters to be taken into account when examining the status of national regulations in Spain on the quality of electricity supply, in addition to describing the various agents intervening in these. There are two more aspects to consider： the guarantee of supply and energy is provided at the lowest cost to consumers. The authors propose to include phase-shifting transformers at specific strategic points, in accordance with power flow control principles in parallel circuits. Finally, it can be concluded that Royal Decree 222/2008 needs reviewing and applying effectively, as do modifications to Royal Decree 1995/2000 providing remuneration that effectively induces electricity companies to invest in their networks, and ends with ＂a well-paid electricity company is obliged to invest in network improvements＂.
