The United States is launching an all-out crackdown against China in the name of competition,which has posed increasingly severe challenges to development and security in China.The strategic competition between China ...The United States is launching an all-out crackdown against China in the name of competition,which has posed increasingly severe challenges to development and security in China.The strategic competition between China and the United States is becoming an essential part of once-in-a-century changes that is shaping the world today.Under such circumstances,the Communist Party of China applies a holistic approach to national security,which aims to balance development and security as well as opening up and security.Furthermore,it intends to implement the national rejuvenation strategy within the wider context of once-ina-century global changes.Managing China’s affairs well to achieve a dynamic balance and positive interaction among high-quality development,high-level security,and high-standard opening-up can provide the basis for realizing the rejuvenation of the Chinese nation and response to containment by the United States.While fostering a new development paradigm,China advances scientific and technological innovation and pursues common prosperity.Moreover,it defends national security through firm but flexible struggles and promotes safe development by accelerating domestic circulation.However,China needs to control the costs of its security investment,pay equal attention to the risks and gains brought about by its opening-up policy,and,thus,enhance its capability to compete with the United States in the long term.展开更多
Four kinds of new macrocycles containing amino acids and nyl-heterocyclic units were synthesized by the condensation of di-esters containing Ts-amino acids units with di-halogenated compounds at room temperature. The ...Four kinds of new macrocycles containing amino acids and nyl-heterocyclic units were synthesized by the condensation of di-esters containing Ts-amino acids units with di-halogenated compounds at room temperature. The macrocycles were characterized by elemental analysis, IR,MS(FAB) and 1H NMR展开更多
Thermal behavior and phase behavior in blends of liquid crystalline poly(aryl ether ketone) with lateral methoxy groups (M-PAEK) and poly(aryl ether ether ketone) containing thioether units (S-PEEK) have been investig...Thermal behavior and phase behavior in blends of liquid crystalline poly(aryl ether ketone) with lateral methoxy groups (M-PAEK) and poly(aryl ether ether ketone) containing thioether units (S-PEEK) have been investigated by differential scanning calorimetry (DSC) and polarized light microscopy (PLM) techniques. The results indicate that the composition of the blends has great effect on the phase behavior and morphology. Thin films of pure M-PAEK and S-PEEK crystallized from the melts exhibit typical mosaic and spherulitic structures, respectively. For the blends with higher M-PAEK contents (> 50%), an unusual ring-banded spherulite with structural discontinuity is formed. The bright core and rings of the ring-banded spherulites under PLM are composed of M-PAEK phase, while the dark rings consist mainly of S-PEEK phase. For the 50:50 M-PAEK/S-PEEK blend, the ring-banded spherulites and S-PEEK spherulites coexist, which implies that a partial phase separation between the two components takes place in the melting state. In S-PEEK-rich blends, a volume-filled spherulite is produced. In addition, the effect of isothermal crystallization temperature on the phase behavior, especially the ring-banded spherulite formation in the blends, is discussed.展开更多
This paper presents design of an self contained actuators unit in wide area damping control of power system in stabilizing system response for both nominal system condition and during actuator faults.First it is prese...This paper presents design of an self contained actuators unit in wide area damping control of power system in stabilizing system response for both nominal system condition and during actuator faults.First it is presented that use of multiple actuators in wide area control aid in improving damping in power system.A wide area damping controller feeding multiple actuators to satisfy multiple objectives in wide area damping control of power system is designed.Minimization of infinity norm of closed loop transfer function of power system with wide area controller in feedback path&closed loop poles placement techniques are used in controller synthesis.Second a reconfigurable control on the lines of fault hiding principle is added to the controller design to maintain system damping to pre-fault level in case of actuator faults.A reconfiguration component(RC)is activated on occurrence of actuator fault thereby reconfiguring system dynamics and redistributing wide area control signal among remaining active actuators.RC together with remaining active actuators and under same wide area damping controller maintains system damping to pre-fault level thereby preserving system dynamic response.In the reconfigurable control design presented here no new actuators outside the unit of actuators designed for wide area damping control is required.This makes for an self contained actuators unit in wide area damping control of power system both for nominal system condition and for system affected by actuator faults.A two area power system model is considered here for demonstrating effectiveness of designed robust damping controller with multiple outputs feeding multiple actuators in wide area control and illustrating the idea of self contained actuators unit for maintaining system damping in case of actuator faults.展开更多
文摘The United States is launching an all-out crackdown against China in the name of competition,which has posed increasingly severe challenges to development and security in China.The strategic competition between China and the United States is becoming an essential part of once-in-a-century changes that is shaping the world today.Under such circumstances,the Communist Party of China applies a holistic approach to national security,which aims to balance development and security as well as opening up and security.Furthermore,it intends to implement the national rejuvenation strategy within the wider context of once-ina-century global changes.Managing China’s affairs well to achieve a dynamic balance and positive interaction among high-quality development,high-level security,and high-standard opening-up can provide the basis for realizing the rejuvenation of the Chinese nation and response to containment by the United States.While fostering a new development paradigm,China advances scientific and technological innovation and pursues common prosperity.Moreover,it defends national security through firm but flexible struggles and promotes safe development by accelerating domestic circulation.However,China needs to control the costs of its security investment,pay equal attention to the risks and gains brought about by its opening-up policy,and,thus,enhance its capability to compete with the United States in the long term.
文摘Four kinds of new macrocycles containing amino acids and nyl-heterocyclic units were synthesized by the condensation of di-esters containing Ts-amino acids units with di-halogenated compounds at room temperature. The macrocycles were characterized by elemental analysis, IR,MS(FAB) and 1H NMR
基金supported by the National Natural Science Foundation of China (50973038)the Basic Research Fund of Jilin University
文摘Thermal behavior and phase behavior in blends of liquid crystalline poly(aryl ether ketone) with lateral methoxy groups (M-PAEK) and poly(aryl ether ether ketone) containing thioether units (S-PEEK) have been investigated by differential scanning calorimetry (DSC) and polarized light microscopy (PLM) techniques. The results indicate that the composition of the blends has great effect on the phase behavior and morphology. Thin films of pure M-PAEK and S-PEEK crystallized from the melts exhibit typical mosaic and spherulitic structures, respectively. For the blends with higher M-PAEK contents (> 50%), an unusual ring-banded spherulite with structural discontinuity is formed. The bright core and rings of the ring-banded spherulites under PLM are composed of M-PAEK phase, while the dark rings consist mainly of S-PEEK phase. For the 50:50 M-PAEK/S-PEEK blend, the ring-banded spherulites and S-PEEK spherulites coexist, which implies that a partial phase separation between the two components takes place in the melting state. In S-PEEK-rich blends, a volume-filled spherulite is produced. In addition, the effect of isothermal crystallization temperature on the phase behavior, especially the ring-banded spherulite formation in the blends, is discussed.
文摘This paper presents design of an self contained actuators unit in wide area damping control of power system in stabilizing system response for both nominal system condition and during actuator faults.First it is presented that use of multiple actuators in wide area control aid in improving damping in power system.A wide area damping controller feeding multiple actuators to satisfy multiple objectives in wide area damping control of power system is designed.Minimization of infinity norm of closed loop transfer function of power system with wide area controller in feedback path&closed loop poles placement techniques are used in controller synthesis.Second a reconfigurable control on the lines of fault hiding principle is added to the controller design to maintain system damping to pre-fault level in case of actuator faults.A reconfiguration component(RC)is activated on occurrence of actuator fault thereby reconfiguring system dynamics and redistributing wide area control signal among remaining active actuators.RC together with remaining active actuators and under same wide area damping controller maintains system damping to pre-fault level thereby preserving system dynamic response.In the reconfigurable control design presented here no new actuators outside the unit of actuators designed for wide area damping control is required.This makes for an self contained actuators unit in wide area damping control of power system both for nominal system condition and for system affected by actuator faults.A two area power system model is considered here for demonstrating effectiveness of designed robust damping controller with multiple outputs feeding multiple actuators in wide area control and illustrating the idea of self contained actuators unit for maintaining system damping in case of actuator faults.
