In the system with two two-level ions confined in a linear trap, this paper presents a simple scheme to realize the quantum phase gate （QPG） and the swap gate beyond the Lamb Dicke （LD） limit. These two-qubit quan...In the system with two two-level ions confined in a linear trap, this paper presents a simple scheme to realize the quantum phase gate （QPG） and the swap gate beyond the Lamb Dicke （LD） limit. These two-qubit quantum logic gates only involve the internal states of two trapped ions. The scheme does not use the vibrational mode as the data bus and only requires a single resonant interaction of the ions with the lasers. Neither the LD approximation nor the auxiliary atomic level is needed in the proposed scheme. Thus the scheme is simple and the interaction time is very short, which is important in view of decoherence. The experimental feasibility for achieving this scheme is also discussed.展开更多
Based on the surface-gate and buried-gate structures,a novel buried-gate structure called the planar type buried-gate (PTBG) structure for static induction devices (SIDs) is proposed.An approach to realize a buried-ga...Based on the surface-gate and buried-gate structures,a novel buried-gate structure called the planar type buried-gate (PTBG) structure for static induction devices (SIDs) is proposed.An approach to realize a buried-gate type static induction transistor by conventional planar process technology is presented.Using this structure,it is successfully avoided the second epitaxy with a high degree of difficulty and the complicated mesa process in conventional buried gate.The experimental results demonstrate that this structure is desirable for application in power SIDs.Its advantages are high breakdown voltage and blocking gain.展开更多
Three recent breakthroughs due to AI in arts and science serve as motivation:An award winning digital image,protein folding,fast matrix multiplication.Many recent developments in artificial neural networks,particularl...Three recent breakthroughs due to AI in arts and science serve as motivation:An award winning digital image,protein folding,fast matrix multiplication.Many recent developments in artificial neural networks,particularly deep learning(DL),applied and relevant to computational mechanics(solid,fluids,finite-element technology)are reviewed in detail.Both hybrid and pure machine learning(ML)methods are discussed.Hybrid methods combine traditional PDE discretizations with ML methods either(1)to help model complex nonlinear constitutive relations,(2)to nonlinearly reduce the model order for efficient simulation(turbulence),or(3)to accelerate the simulation by predicting certain components in the traditional integration methods.Here,methods(1)and(2)relied on Long-Short-Term Memory(LSTM)architecture,with method(3)relying on convolutional neural networks.Pure ML methods to solve(nonlinear)PDEs are represented by Physics-Informed Neural network(PINN)methods,which could be combined with attention mechanism to address discontinuous solutions.Both LSTM and attention architectures,together with modern and generalized classic optimizers to include stochasticity for DL networks,are extensively reviewed.Kernel machines,including Gaussian processes,are provided to sufficient depth for more advanced works such as shallow networks with infinite width.Not only addressing experts,readers are assumed familiar with computational mechanics,but not with DL,whose concepts and applications are built up from the basics,aiming at bringing first-time learners quickly to the forefront of research.History and limitations of AI are recounted and discussed,with particular attention at pointing out misstatements or misconceptions of the classics,even in well-known references.Positioning and pointing control of a large-deformable beam is given as an example.展开更多
集成门极换流晶闸管（integrated gate commutated thyristor,IGCT）具有大电流导通损耗低和关断过程快速均匀可靠等特性,在固态限流器（solid state fault current limiter,SSFCL）应用中具有综合优势。为此,针对固态限流器中并联运行...集成门极换流晶闸管（integrated gate commutated thyristor,IGCT）具有大电流导通损耗低和关断过程快速均匀可靠等特性,在固态限流器（solid state fault current limiter,SSFCL）应用中具有综合优势。为此,针对固态限流器中并联运行的大功率IGCT,通过构建器件的集总电荷仿真模型对其关断过程进行了仿真分析,并结合试验验证深入研究了RC阻容缓冲和压敏电阻保护对并联IGCT关断特性的影响。大电流关断研究结果表明：RC缓冲能进一步缓解并联IGCT关断过程中的电流拥挤现象,降低拖尾电流下降率,减轻器件动态雪崩击穿的剧烈程度;在固态限流器中回路电感和关断电流均比较大的条件下,增加RC缓冲能大幅提高并联器件的关断可靠性。该研究成果可以为并联IGCT有效保护方案的设计提供参考。展开更多
基金Project supported by the Important Program of Hunan Provincial Education Department (Grant No 06A038)Department of Education of Hunan Province (Grant No 06C080)+1 种基金Natural Science Foundation of Hunan Province, China (Grant No 07JJ3013)Postdoctoral Fund of China (Grant No 20070420825)
文摘In the system with two two-level ions confined in a linear trap, this paper presents a simple scheme to realize the quantum phase gate （QPG） and the swap gate beyond the Lamb Dicke （LD） limit. These two-qubit quantum logic gates only involve the internal states of two trapped ions. The scheme does not use the vibrational mode as the data bus and only requires a single resonant interaction of the ions with the lasers. Neither the LD approximation nor the auxiliary atomic level is needed in the proposed scheme. Thus the scheme is simple and the interaction time is very short, which is important in view of decoherence. The experimental feasibility for achieving this scheme is also discussed.
文摘Based on the surface-gate and buried-gate structures,a novel buried-gate structure called the planar type buried-gate (PTBG) structure for static induction devices (SIDs) is proposed.An approach to realize a buried-gate type static induction transistor by conventional planar process technology is presented.Using this structure,it is successfully avoided the second epitaxy with a high degree of difficulty and the complicated mesa process in conventional buried gate.The experimental results demonstrate that this structure is desirable for application in power SIDs.Its advantages are high breakdown voltage and blocking gain.
文摘Three recent breakthroughs due to AI in arts and science serve as motivation:An award winning digital image,protein folding,fast matrix multiplication.Many recent developments in artificial neural networks,particularly deep learning(DL),applied and relevant to computational mechanics(solid,fluids,finite-element technology)are reviewed in detail.Both hybrid and pure machine learning(ML)methods are discussed.Hybrid methods combine traditional PDE discretizations with ML methods either(1)to help model complex nonlinear constitutive relations,(2)to nonlinearly reduce the model order for efficient simulation(turbulence),or(3)to accelerate the simulation by predicting certain components in the traditional integration methods.Here,methods(1)and(2)relied on Long-Short-Term Memory(LSTM)architecture,with method(3)relying on convolutional neural networks.Pure ML methods to solve(nonlinear)PDEs are represented by Physics-Informed Neural network(PINN)methods,which could be combined with attention mechanism to address discontinuous solutions.Both LSTM and attention architectures,together with modern and generalized classic optimizers to include stochasticity for DL networks,are extensively reviewed.Kernel machines,including Gaussian processes,are provided to sufficient depth for more advanced works such as shallow networks with infinite width.Not only addressing experts,readers are assumed familiar with computational mechanics,but not with DL,whose concepts and applications are built up from the basics,aiming at bringing first-time learners quickly to the forefront of research.History and limitations of AI are recounted and discussed,with particular attention at pointing out misstatements or misconceptions of the classics,even in well-known references.Positioning and pointing control of a large-deformable beam is given as an example.
文摘集成门极换流晶闸管（integrated gate commutated thyristor,IGCT）具有大电流导通损耗低和关断过程快速均匀可靠等特性,在固态限流器（solid state fault current limiter,SSFCL）应用中具有综合优势。为此,针对固态限流器中并联运行的大功率IGCT,通过构建器件的集总电荷仿真模型对其关断过程进行了仿真分析,并结合试验验证深入研究了RC阻容缓冲和压敏电阻保护对并联IGCT关断特性的影响。大电流关断研究结果表明：RC缓冲能进一步缓解并联IGCT关断过程中的电流拥挤现象,降低拖尾电流下降率,减轻器件动态雪崩击穿的剧烈程度;在固态限流器中回路电感和关断电流均比较大的条件下,增加RC缓冲能大幅提高并联器件的关断可靠性。该研究成果可以为并联IGCT有效保护方案的设计提供参考。
