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Dong Yuan,Li Shu-Tao,Guan Jia-Yin,Zhang Xi-He,Jin Guang-Yong 한국광학회 2016 Current Optics and Photonics Vol.20 No.5
In this paper, by using the Rayleigh-Sommer field theory and the cross-spectral density function, theanalytical expression for the intensity distribution of a double half-Gaussian hollow beam in a turbulentatmosphere is obtained. The influence of the initial spot size of this beam on its propagation propertiesin a turbulent atmosphere is simulated, and the intensity distributions for such beams with different spotsizes are obtained. The results show that the initial spot size has an important influence on the propagationproperties in the near field, while this influence in the far field is very weak.
THE BUSH DOCTRINE: CHINESE PERSPECTIVES AND RESPONSES
Jing-DongYuan 경남대학교 극동문제연구소 2003 ASIAN PERSPECTIVE Vol.27 No.4
The Bush Doctrine has important implications for China. It challenges principles that Beijing holds dear with respect to state sovereignty, multipolarity, and the role of international organizations. Continued American primacy in international affairs marginalizes China’s importance. In addition, key elements of the Bush Doctrine such as preemption, missile defenses, and a growing U.S. military presence as a result of the war against terrorism directly affect Chinese national security interests. However, while Beijing has a very negative view of the Bush Doctrine, its responses have been more measured and pragmatic. China recognizes its own limitation and the need to avoid direct confrontation with the United States. Its leaders also believe that the Bush Doctrine will have limited application to only a few exceptional cases simply because unilateralism cannot be sustained long in the face of domestic and international opposition. Instead, Beijing seized the opportunity provided by 9-11 and the changing focus of U.S. security policy to expand areas of common interest while minimizing the impact of differences. How the Bush Doctrine will affect China’s interests in the future will depend on how well the two manage their increasingly complex relationship.
The Effectiveness of Single Price Change in Learning and Earning via Sequential Estimation
김정현,( Dongyuan Zhan ),( Chihoon Lee ) 한국품질경영학회 2021 한국품질경영학회 학술대회 Vol.2021 No.-
We study a revenue maximization problem in a congestible system with unknown demand parameters. We show that a single price change during the learning phase is sufficient to obtain a revenue regret that is on the same scale with the optimal regret achievable when demand parameters are known up front. The sufficiency of single price change in learning is due to the implementation of sequential maximum likelihood estimation (SMLE). Without knowledge of demand parameters, an initial price is randomly chosen. With a typical MLE under which a sample siae for learning is pre-fixed, the quality of estimation with the randomly chosen price is not controllable, making the choice of the second price as equally uninformative as for the first price. On the other hand, SMLE makes learning with the first price informative as it can control the estimation quality.
A New Definition of Short-circuit Ratio for Multi-converter HVDC Systems
Dengfeng Liu,Dongyuan Shi,Yinhong Li 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.5
In this paper, a new definition of short-circuit ratio concept for multi-converter HVDC systems is proposed. Analysis results of voltage interaction between converters show that the reactive power-voltage characteristic of a converter has a dominant effect on voltage interaction level compared with its active power-voltage characteristic. Such a relation between converter reactive power and voltage interaction level supports taking the former into account in the definition of short-circuit ratio concept for multi-converter systems. The proposed definition is verified by the method of maximum power curve for various system configurations. Furthermore, a formula to calculate transient overvoltage for multi-converter systems is derived based on the proposed definition, and the efficiency of the derived formula is verified.
Pingping Xie,Dongyuan Shi,Yinhong Li 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.2
Application of demand-side resources to automatic generation control (AGC) has a great significance for improving the dynamic control performance of power system frequency regulation. This paper investigates the possibility of providing regulation services by demand-side energy storage in electric vehicle battery swapping stations (BSS). An interaction framework, namely station-to-grid (S2G), is presented to integrate BSS energy storage into power grid for giving benefits to frequency regulation. The BSS can be regarded as a lumped battery energy storage station through S2G framework. A supplementary AGC method using demand-side BSS energy storage is developed considering the vehicle user demand of battery swapping. The effects to the AGC performance are evaluated through simulations by using a two-area interconnected power grid model with step and random load disturbance. The results show that the demand-side BSS can significantly suppress the frequency deviation and tie-line power fluctuations.
Xie, Pingping,Shi, Dongyuan,Li, Yinhong The Korean Institute of Electrical Engineers 2016 Journal of Electrical Engineering & Technology Vol.11 No.2
Application of demand-side resources to automatic generation control (AGC) has a great significance for improving the dynamic control performance of power system frequency regulation. This paper investigates the possibility of providing regulation services by demand-side energy storage in electric vehicle battery swapping stations (BSS). An interaction framework, namely station-to-grid (S2G), is presented to integrate BSS energy storage into power grid for giving benefits to frequency regulation. The BSS can be regarded as a lumped battery energy storage station through S2G framework. A supplementary AGC method using demand-side BSS energy storage is developed considering the vehicle user demand of battery swapping. The effects to the AGC performance are evaluated through simulations by using a two-area interconnected power grid model with step and random load disturbance. The results show that the demand-side BSS can significantly suppress the frequency deviation and tie-line power fluctuations.
A New Definition of Short-circuit Ratio for Multi-converter HVDC Systems
Liu, Dengfeng,Shi, Dongyuan,Li, Yinhong The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.5
In this paper, a new definition of short-circuit ratio concept for multi-converter HVDC systems is proposed. Analysis results of voltage interaction between converters show that the reactive power-voltage characteristic of a converter has a dominant effect on voltage interaction level compared with its active power-voltage characteristic. Such a relation between converter reactive power and voltage interaction level supports taking the former into account in the definition of short-circuit ratio concept for multi-converter systems. The proposed definition is verified by the method of maximum power curve for various system configurations. Furthermore, a formula to calculate transient overvoltage for multi-converter systems is derived based on the proposed definition, and the efficiency of the derived formula is verified.