Simultaneously imposed challenges of highvoltage insulation,high dv/dt,highswitching frequency,fast protection,and thermal management associated with the adoption of 10 kV SiC MOSFET,often pose nearly insurmountable b...Simultaneously imposed challenges of highvoltage insulation,high dv/dt,highswitching frequency,fast protection,and thermal management associated with the adoption of 10 kV SiC MOSFET,often pose nearly insurmountable barriers to potential users,undoubtedly hindering their penetration in mediumvoltage(MV)power conversion.Key novel technologies such as enhanced gatedriver,auxiliary power supply network,PCB planar dcbus,and highdensity inductor are presented,enabling the SiCbased designs in modular MV converters,overcoming aforementioned challenges.However,purely substituting SiC design instead of Sibased ones in modular MV converters,would expectedly yield only limited gains.Therefore,to further elevate SiCbased designs,novel highbandwidth control strategies such as switchingcycle control(SCC)and integrated capacitorblocked transistor(ICBT),as well as highperformance/highbandwidth communication network are developed.All these technologies combined,overcome barriers posed by stateoftheart Si designs and unlock system level benefits such as very high power density,highefficiency,fast dynamic response,unrestricted line frequency operation,and improved power quality,all demonstrated throughout this paper.展开更多
China’s BeiDou Navigation Satellite System(BDS)construction has been completed and the system has been formally commissioned.Most of the Electric Power Systems(EPSs)for MEO satellites were developed by the Shanghai I...China’s BeiDou Navigation Satellite System(BDS)construction has been completed and the system has been formally commissioned.Most of the Electric Power Systems(EPSs)for MEO satellites were developed by the Shanghai Institute of Space Power-sources.The 42 V medium-voltage fully-regulated high-power EPS has been adopted for the first time in medium Earth orbit,with an output power reaching about 3 kW.Compared with the 42 V medium-voltage semi-regulated bus power system used in the Regional Navigation BDS-2 satellite,the EPS of the BDS-3 MEO satellites has increased power by about 80%,adopting many newly developed products such as high-efficient triple junction GaAs solar cells,high-energy-density lithium ion batteries and a high-efficient autonomous power control unit(PCU).Based on the studies on the medium-voltage fully-regulated and high-power EPS technical principles,and the adaptability and reliability of various working modes,the test verifications for the EPS were conducted both on the ground and in orbit.Compared with other global navigation satellite systems such as GPS,Galileo and GLONASS,the EPS of the BDS-3 MEO satellite has a long design life time which is equivalent to that of the GPS and Galileo,but with a larger power supply capability and power ratio,distinguishing its advancement in the field of satellite power technology.展开更多
The most crucial requirement in radiation therapy treatment planning is a fast and accurate treatment planning system that minimizes damage to healthy tissues surrounding cancer cells. The use of Monte Carlo toolkits ...The most crucial requirement in radiation therapy treatment planning is a fast and accurate treatment planning system that minimizes damage to healthy tissues surrounding cancer cells. The use of Monte Carlo toolkits has become indispensable for research aimed at precisely determining the dose in radiotherapy. Among the numerous algorithms developed in recent years, the GAMOS code, which utilizes the Geant4 toolkit for Monte Carlo simula-tions, incorporates various electromagnetic physics models and multiple scattering models for simulating particle interactions with matter. This makes it a valuable tool for dose calculations in medical applications and throughout the patient’s volume. The aim of this present work aims to vali-date the GAMOS code for the simulation of a 6 MV photon-beam output from the Elekta Synergy Agility linear accelerator. The simulation involves mod-eling the major components of the accelerator head and the interactions of the radiation beam with a homogeneous water phantom and particle information was collected following the modeling of the phase space. This space was po-sitioned under the X and Y jaws, utilizing three electromagnetic physics mod-els of the GAMOS code: Standard, Penelope, and Low-Energy, along with three multiple scattering models: Goudsmit-Saunderson, Urban, and Wentzel-VI. The obtained phase space file was used as a particle source to simulate dose distributions (depth-dose and dose profile) for field sizes of 5 × 5 cm<sup>2</sup> and 10 × 10 cm<sup>2</sup> at depths of 10 cm and 20 cm in a water phantom, with a source-surface distance (SSD) of 90 cm from the target. We compared the three electromagnetic physics models and the three multiple scattering mod-els of the GAMOS code to experimental results. Validation of our results was performed using the gamma index, with an acceptability criterion of 3% for the dose difference (DD) and 3 mm for the distance-to-agreement (DTA). We achieved agreements of 94% and 96%, respectively, between simulation and experimentation for the three electromagnetic physics models and three mul-tiple scattering models, for field sizes of 5 × 5 cm<sup>2</sup> and 10 × 10 cm<sup>2</sup> for depth-dose curves. For dose profile curves, a good agreement of 100% was found between simulation and experimentation for the three electromagnetic physics models, as well as for the three multiple scattering models for a field size of 5 × 5 cm<sup>2</sup> at 10 cm and 20 cm depths. For a field size of 10 × 10 cm<sup>2</sup>, the Penelope model dominated with 98% for 10 cm, along with the three multiple scattering models. The Penelope model and the Standard model, along with the three multiple scattering models, dominated with 100% for 20 cm. Our study, which compared these different GAMOS code models, can be crucial for enhancing the accuracy and quality of radiotherapy, contributing to more effective patient treatment. Our research compares various electro-magnetic physics models and multiple scattering models with experimental measurements, enabling us to choose the models that produce the most reli-able results, thereby directly impacting the quality of simulations. This en-hances confidence in using these models for treatment planning. Our re-search consistently contributes to the progress of Monte Carlo simulation techniques in radiation therapy, enriching the scientific literature.展开更多
以青海省海西州乌兰县某测区为实验区,利用SfM-MVS(Structure from Motion with Multi-view Stereo)技术对无人机航摄数据进行处理,分析了不同控制点布设方案下的数据处理精度,完成了测区高质量三维点云数据的获取和DEM构建。结果表明:...以青海省海西州乌兰县某测区为实验区,利用SfM-MVS(Structure from Motion with Multi-view Stereo)技术对无人机航摄数据进行处理,分析了不同控制点布设方案下的数据处理精度,完成了测区高质量三维点云数据的获取和DEM构建。结果表明:采用SfM-MVS技术处理数据能够满足实验区设计测图精度要求,该方法在高山地区大比例尺地形图测绘方面具有可行性。展开更多
基金conducted under ARPA-e from DOE with the award number DE-AR0000892.
文摘Simultaneously imposed challenges of highvoltage insulation,high dv/dt,highswitching frequency,fast protection,and thermal management associated with the adoption of 10 kV SiC MOSFET,often pose nearly insurmountable barriers to potential users,undoubtedly hindering their penetration in mediumvoltage(MV)power conversion.Key novel technologies such as enhanced gatedriver,auxiliary power supply network,PCB planar dcbus,and highdensity inductor are presented,enabling the SiCbased designs in modular MV converters,overcoming aforementioned challenges.However,purely substituting SiC design instead of Sibased ones in modular MV converters,would expectedly yield only limited gains.Therefore,to further elevate SiCbased designs,novel highbandwidth control strategies such as switchingcycle control(SCC)and integrated capacitorblocked transistor(ICBT),as well as highperformance/highbandwidth communication network are developed.All these technologies combined,overcome barriers posed by stateoftheart Si designs and unlock system level benefits such as very high power density,highefficiency,fast dynamic response,unrestricted line frequency operation,and improved power quality,all demonstrated throughout this paper.
文摘China’s BeiDou Navigation Satellite System(BDS)construction has been completed and the system has been formally commissioned.Most of the Electric Power Systems(EPSs)for MEO satellites were developed by the Shanghai Institute of Space Power-sources.The 42 V medium-voltage fully-regulated high-power EPS has been adopted for the first time in medium Earth orbit,with an output power reaching about 3 kW.Compared with the 42 V medium-voltage semi-regulated bus power system used in the Regional Navigation BDS-2 satellite,the EPS of the BDS-3 MEO satellites has increased power by about 80%,adopting many newly developed products such as high-efficient triple junction GaAs solar cells,high-energy-density lithium ion batteries and a high-efficient autonomous power control unit(PCU).Based on the studies on the medium-voltage fully-regulated and high-power EPS technical principles,and the adaptability and reliability of various working modes,the test verifications for the EPS were conducted both on the ground and in orbit.Compared with other global navigation satellite systems such as GPS,Galileo and GLONASS,the EPS of the BDS-3 MEO satellite has a long design life time which is equivalent to that of the GPS and Galileo,but with a larger power supply capability and power ratio,distinguishing its advancement in the field of satellite power technology.
文摘The most crucial requirement in radiation therapy treatment planning is a fast and accurate treatment planning system that minimizes damage to healthy tissues surrounding cancer cells. The use of Monte Carlo toolkits has become indispensable for research aimed at precisely determining the dose in radiotherapy. Among the numerous algorithms developed in recent years, the GAMOS code, which utilizes the Geant4 toolkit for Monte Carlo simula-tions, incorporates various electromagnetic physics models and multiple scattering models for simulating particle interactions with matter. This makes it a valuable tool for dose calculations in medical applications and throughout the patient’s volume. The aim of this present work aims to vali-date the GAMOS code for the simulation of a 6 MV photon-beam output from the Elekta Synergy Agility linear accelerator. The simulation involves mod-eling the major components of the accelerator head and the interactions of the radiation beam with a homogeneous water phantom and particle information was collected following the modeling of the phase space. This space was po-sitioned under the X and Y jaws, utilizing three electromagnetic physics mod-els of the GAMOS code: Standard, Penelope, and Low-Energy, along with three multiple scattering models: Goudsmit-Saunderson, Urban, and Wentzel-VI. The obtained phase space file was used as a particle source to simulate dose distributions (depth-dose and dose profile) for field sizes of 5 × 5 cm<sup>2</sup> and 10 × 10 cm<sup>2</sup> at depths of 10 cm and 20 cm in a water phantom, with a source-surface distance (SSD) of 90 cm from the target. We compared the three electromagnetic physics models and the three multiple scattering mod-els of the GAMOS code to experimental results. Validation of our results was performed using the gamma index, with an acceptability criterion of 3% for the dose difference (DD) and 3 mm for the distance-to-agreement (DTA). We achieved agreements of 94% and 96%, respectively, between simulation and experimentation for the three electromagnetic physics models and three mul-tiple scattering models, for field sizes of 5 × 5 cm<sup>2</sup> and 10 × 10 cm<sup>2</sup> for depth-dose curves. For dose profile curves, a good agreement of 100% was found between simulation and experimentation for the three electromagnetic physics models, as well as for the three multiple scattering models for a field size of 5 × 5 cm<sup>2</sup> at 10 cm and 20 cm depths. For a field size of 10 × 10 cm<sup>2</sup>, the Penelope model dominated with 98% for 10 cm, along with the three multiple scattering models. The Penelope model and the Standard model, along with the three multiple scattering models, dominated with 100% for 20 cm. Our study, which compared these different GAMOS code models, can be crucial for enhancing the accuracy and quality of radiotherapy, contributing to more effective patient treatment. Our research compares various electro-magnetic physics models and multiple scattering models with experimental measurements, enabling us to choose the models that produce the most reli-able results, thereby directly impacting the quality of simulations. This en-hances confidence in using these models for treatment planning. Our re-search consistently contributes to the progress of Monte Carlo simulation techniques in radiation therapy, enriching the scientific literature.
文摘以青海省海西州乌兰县某测区为实验区,利用SfM-MVS(Structure from Motion with Multi-view Stereo)技术对无人机航摄数据进行处理,分析了不同控制点布设方案下的数据处理精度,完成了测区高质量三维点云数据的获取和DEM构建。结果表明:采用SfM-MVS技术处理数据能够满足实验区设计测图精度要求,该方法在高山地区大比例尺地形图测绘方面具有可行性。
