The quantum private query(QPQ)is a quantum solution for the symmetrically private information retrieval problem.We study the security of quantum-key-distribution-based QPQ with weak coherent pulses.The result shows th...The quantum private query(QPQ)is a quantum solution for the symmetrically private information retrieval problem.We study the security of quantum-key-distribution-based QPQ with weak coherent pulses.The result shows that multiphoton pulses have posed a serious threat to the participant’s privacy in QPQ protocols.Then we propose a decoy-state method that can help the honest participant detect the attack by exploiting multiphoton pulses and improving the key distillation process to defend against such attack.The analysis demonstrates that our decoy-state method significantly improves the security of the QPQ with weak coherent pulses,which solves a major obstacle in the practical application of the QPQ.展开更多
The Lie symmetry analysis is performed for the coupled short plus （CSP） equation. We derive the infinitesimals that admit the classical symmetry group. Five types arise depending on the nature of the Lie symmetry ge...The Lie symmetry analysis is performed for the coupled short plus （CSP） equation. We derive the infinitesimals that admit the classical symmetry group. Five types arise depending on the nature of the Lie symmetry generator. In all types, we find reductions in terms of system of ordinary differential equations, and exact solutions of the CSP equation are derived, which are compared with numerical solutions using the classical fourth-order Runge-Kutta scheme.展开更多
静止无功发生器(static var generator,SVG)广泛用于电力系统中解决三相不平衡的问题。采用构造一个无延迟的旋转相量的方法,对静止无功发生器的电流检测部分进行了改进,以解决移相算子带来的延迟导致的误差,提升电流检测的实时性。控...静止无功发生器(static var generator,SVG)广泛用于电力系统中解决三相不平衡的问题。采用构造一个无延迟的旋转相量的方法,对静止无功发生器的电流检测部分进行了改进,以解决移相算子带来的延迟导致的误差,提升电流检测的实时性。控制部分的电流内环采用前馈解耦控制,以解决dq轴上直流变量的耦合问题;由于PI控制系统具有参数难以确定以及难以解决时变复杂系统的缺点,提出了在前馈解耦控制器中使用超螺旋二阶滑模控制的输出电压波形控制方案来代替PI控制。依托这种方法在Matlab中设计出静止无功发生器的模型,对动态三相不平衡负载进行仿真分析。由仿真结果可知,与传统的PI控制相比,此种方法控制效果更好。展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.62171418,U19A2076,61901425,and 61702061)Natural Science Foundation of Chongqing(Grant No.cstc2020jcyjmsxm X0719)+2 种基金National Science Key Lab Fund Project(Grant No.6142103200105)Fundamental Research Funds for the Central Universities(Grant Nos.2020CDJQY-A018,and 2020CDJ-LHZZ-056)Sichuan Science and Technology Program(Grant No.019JDJQ0060)。
文摘The quantum private query(QPQ)is a quantum solution for the symmetrically private information retrieval problem.We study the security of quantum-key-distribution-based QPQ with weak coherent pulses.The result shows that multiphoton pulses have posed a serious threat to the participant’s privacy in QPQ protocols.Then we propose a decoy-state method that can help the honest participant detect the attack by exploiting multiphoton pulses and improving the key distillation process to defend against such attack.The analysis demonstrates that our decoy-state method significantly improves the security of the QPQ with weak coherent pulses,which solves a major obstacle in the practical application of the QPQ.
文摘The Lie symmetry analysis is performed for the coupled short plus （CSP） equation. We derive the infinitesimals that admit the classical symmetry group. Five types arise depending on the nature of the Lie symmetry generator. In all types, we find reductions in terms of system of ordinary differential equations, and exact solutions of the CSP equation are derived, which are compared with numerical solutions using the classical fourth-order Runge-Kutta scheme.
文摘静止无功发生器(static var generator,SVG)广泛用于电力系统中解决三相不平衡的问题。采用构造一个无延迟的旋转相量的方法,对静止无功发生器的电流检测部分进行了改进,以解决移相算子带来的延迟导致的误差,提升电流检测的实时性。控制部分的电流内环采用前馈解耦控制,以解决dq轴上直流变量的耦合问题;由于PI控制系统具有参数难以确定以及难以解决时变复杂系统的缺点,提出了在前馈解耦控制器中使用超螺旋二阶滑模控制的输出电压波形控制方案来代替PI控制。依托这种方法在Matlab中设计出静止无功发生器的模型,对动态三相不平衡负载进行仿真分析。由仿真结果可知,与传统的PI控制相比,此种方法控制效果更好。
