Whether the breakdown structure and coding system of construction projects are reasonable or not determines to a large degree the performance level of the entire project management. We analyze in detail the similariti...Whether the breakdown structure and coding system of construction projects are reasonable or not determines to a large degree the performance level of the entire project management. We analyze in detail the similarities and differences of two kinds of decomposing methods classified by type of work and construction elements based on the discussion of international typical coding standards system designing. We then deduce the differential coefficient relation between project breakdown structure (PBS) and work breakdown structure (WBS). At the same time we constitute a comprehensive construction project breakdown system including element code and type of work code and make a further schematic presentation of the implementation of the system’s functions.展开更多
The results of experiments with rapidly exploding thin conductors inthe current-pause regime are presented.Copper wires 25mmin diameter and 12 mm in length serve as loads for a GVP pulsed generator based on a low-indu...The results of experiments with rapidly exploding thin conductors inthe current-pause regime are presented.Copper wires 25mmin diameter and 12 mm in length serve as loads for a GVP pulsed generator based on a low-inductance capacitor.The generator produces current pulses of up to 10 kA with dI/dt up to 50 A/ns.A 100–800-ns current-pause regime is obtained for charging voltages of 10–15 kV.The discharge channel structure is studied by shadow photography using 0.53-mm,10-ns second-harmonic pulses from aNd31:YAG laser.In the experiments,three types of secondary breakdown are observed,with different symmetry types,different current-pause durations,and different dependences on the energy deposited into the wire during its resistive heating.All of these breakdown types develop inside a tubular core that is produced in the current-pause stage and that remains almost undamaged by the breakdown.展开更多
The comparison of domestic and foreign studies has been utilized to extensively employ junction termination extension(JTE)structures for power devices.However,achieving a gradual doping concentration change in the lat...The comparison of domestic and foreign studies has been utilized to extensively employ junction termination extension(JTE)structures for power devices.However,achieving a gradual doping concentration change in the lateral direction is difficult for SiC devices since the diffusion constants of the implanted aluminum ions in SiC are much less than silicon.Many previously reported studies adopted many new structures to solve this problem.Additionally,the JTE structure is strongly sensitive to the ion implantation dose.Thus,GA-JTE,double-zone etched JTE structures,and SM-JTE with modulation spacing were reported to overcome the above shortcomings of the JTE structure and effectively increase the breakdown voltage.They provided a theoretical basis for fabricating terminal structures of 4H-SiC PiN diodes.This paper summarized the effects of different terminal structures on the electrical properties of SiC devices at home and abroad.Presently,the continuous development and breakthrough of terminal technology have significantly improved the breakdown voltage and terminal efficiency of 4H-SiC PiN power diodes.展开更多
文摘Whether the breakdown structure and coding system of construction projects are reasonable or not determines to a large degree the performance level of the entire project management. We analyze in detail the similarities and differences of two kinds of decomposing methods classified by type of work and construction elements based on the discussion of international typical coding standards system designing. We then deduce the differential coefficient relation between project breakdown structure (PBS) and work breakdown structure (WBS). At the same time we constitute a comprehensive construction project breakdown system including element code and type of work code and make a further schematic presentation of the implementation of the system’s functions.
基金This work was supported in part by the NNSA Stewardship Sciences Academic Programs through DOE Cooperative Agreement DE-NA0001836.
文摘The results of experiments with rapidly exploding thin conductors inthe current-pause regime are presented.Copper wires 25mmin diameter and 12 mm in length serve as loads for a GVP pulsed generator based on a low-inductance capacitor.The generator produces current pulses of up to 10 kA with dI/dt up to 50 A/ns.A 100–800-ns current-pause regime is obtained for charging voltages of 10–15 kV.The discharge channel structure is studied by shadow photography using 0.53-mm,10-ns second-harmonic pulses from aNd31:YAG laser.In the experiments,three types of secondary breakdown are observed,with different symmetry types,different current-pause durations,and different dependences on the energy deposited into the wire during its resistive heating.All of these breakdown types develop inside a tubular core that is produced in the current-pause stage and that remains almost undamaged by the breakdown.
基金financially supported by the Scientific and Technology Project of State Grid Corporation of China,Research on Dry Etching Forming Technology of Silicon Carbide Device,Project No.5500-202158437A-0-0-00.
文摘The comparison of domestic and foreign studies has been utilized to extensively employ junction termination extension(JTE)structures for power devices.However,achieving a gradual doping concentration change in the lateral direction is difficult for SiC devices since the diffusion constants of the implanted aluminum ions in SiC are much less than silicon.Many previously reported studies adopted many new structures to solve this problem.Additionally,the JTE structure is strongly sensitive to the ion implantation dose.Thus,GA-JTE,double-zone etched JTE structures,and SM-JTE with modulation spacing were reported to overcome the above shortcomings of the JTE structure and effectively increase the breakdown voltage.They provided a theoretical basis for fabricating terminal structures of 4H-SiC PiN diodes.This paper summarized the effects of different terminal structures on the electrical properties of SiC devices at home and abroad.Presently,the continuous development and breakthrough of terminal technology have significantly improved the breakdown voltage and terminal efficiency of 4H-SiC PiN power diodes.
