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A New BODIPY Derivative Bearing Piperazine Group
Qi, Xin,Kim, Sook-Kyung,Jun, Eun-Jin,Xu, Li,Kim, Sung-Jin,Yoon, Ju-Young Korean Chemical Society 2007 Bulletin of the Korean Chemical Society Vol.28 No.12
A new BODIPY derivative bearing piperazine group was synthesized and its fluorescent changes towards metal ions as well as pH are studied. The title compound displayed a moderate selectivity for Hg2+ among the metal ions examined.
A Robust Speed Controller with Smith Predictor for A PMSM Drive System with Time Delay
Qixin Zhu,Lei Xiong,Hongli Liu 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.5
In this paper, using H∞control theory, a robust speed controller with smith predictor is proposed toimprove the speed control performance of the permanent magnet synchronous motor (PMSM) servo system withtime delay. The robust speed controller is designed to improve the robustness of control system. Meanwhile,considering the time delay of the system, the speed controller combined with smith predictor is used to compensatethe impact of system time delay. Firstly, based on theH∞state space (time domain) method, a robust speed controlleris established, which has simple structure and easy to be realized. Secondly, theH∞robust standard design problem istransformed to an optimization solution of the linear matrix inequalities (LMIs). Thirdly, a smith predictor is stalledat the parallel position of the robust speed controller, which is of great help to improve the performance of the servosystem with time delay. Finally, simulation results demonstrate that compared with traditional PI controller, thenovel robust controller has better control performance and the robust controller with smith predictor is effective forthe PMSM drive system with time delay.
Quantifying AS Path Inflation by Routing Policies
Qixin Gao,Feng Wang,Lixin Gao 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.1
A route in the Internet may take a longer AS path than the shortest AS path due to routing policies. In this paper, we systematically analyze AS paths and quantify the extent to which routing policies inflate AS paths. The results show that AS path inflation in the Internet is more prevalent than expected. We first present the extent of AS path inflation observed from the RouteView and RIPE routing tables. We then employ three common routing policies to show the extent of AS path inflation. We find that No-Valley routing policy causes the least AS path inflation among the three routing policies. Prefer-Customer-and-Peer-over-Provider policy causes the most AS path inflation. In addition, we find that single-homed stub ASes experience more path inflations than transit ASes and multi-homed ASes. The AS pairs with shortest AS path of 3 AS hops experience more path inflations than other AS pairs. Finally, we investigate the AS path inflation on the end-to-end path from end users to two popular content providers, Google and Comcast. Although the majority of the shortest AS paths from end users to the two providers consists of no more than three AS hops, the actual end-to-end paths that the traffic will take are longer than the shortest AS paths in many cases. Quantifying AS path inflation in the Internet has important implications on the extent of routing policies, traffic engineering performed on the Internet, and BGP convergence speed.