In the present paper we consider sequences of rational functions with a bounded number or free poles con- verging uniformly with a maximum geometric rate to a holomorphic function on a regular set,and we examine the l...In the present paper we consider sequences of rational functions with a bounded number or free poles con- verging uniformly with a maximum geometric rate to a holomorphic function on a regular set,and we examine the limiting distribution of the Zeros and its relations with the phenomenon of overconvergence.Our results further extend the well known classical theory of overconvergence and the zeros of sections of Taylor series.展开更多
In this paper we propose a new class of ternary Zero Correlation Zone (ZCZ) sequence sets based on binary ZCZ sequence sets construction. It is shown that the proposed ternary ZCZ sequence sets can reach the upper bou...In this paper we propose a new class of ternary Zero Correlation Zone (ZCZ) sequence sets based on binary ZCZ sequence sets construction. It is shown that the proposed ternary ZCZ sequence sets can reach the upper bound on the ZCZ sequences. The performance of the proposed sequences set in asynchronous Direct Sequence-Code Division Multiple Access (DS-CDMA) system is evaluated. In the simulation we used two types of channels: Additive White Gaussian Noise (AWGN) and frequency non-selective fading with AWGN noise. The proposed ternary ZCZ sequence sets show better results, in term of Bit Error Rate (BER), than Hayashi’s ternary ZCZ sequence sets.展开更多
To improve the accuracy of the stator winding fault diagnosis in induction motor,a new diagnostic method based on the Hilbert-Huang transform(HHT)was proposed.The ratio of fundamental zero sequence voltage to positive...To improve the accuracy of the stator winding fault diagnosis in induction motor,a new diagnostic method based on the Hilbert-Huang transform(HHT)was proposed.The ratio of fundamental zero sequence voltage to positive sequence voltage after switch-off was selected as the stator fault characteristic,which could effectively avoid the influence of the supply unbalance and the load fluctuation,and directly represent the asymmetry in the stator.Using the empirical mode decomposition(EMD)based on HHT,the zero sequence voltage after switch-off was decomposed and the fundamental component was extracted.Then,the fault characteristic can be acquired.Experimental results on a 4-kW induction motor demonstrate the feasibility and effectiveness of this method.展开更多
In this paper, a multicarrier DS-CDMA system which employs Z-Complementary Se- quences (ZCS) as spreading code is investigated. The new system can not only eliminate multipath interference and Multiple Access Interfer...In this paper, a multicarrier DS-CDMA system which employs Z-Complementary Se- quences (ZCS) as spreading code is investigated. The new system can not only eliminate multipath interference and Multiple Access Interference (MAI), but also support flexible number of users com- pared with system using Orthogonal Complementary (OC) codes. Multicarrier DS-CDMA using OC codes can be regarded as a special case of our proposed system. Zero Correlation Zone (ZCZ) of ZCS can be flexibly adjusted to meet the requirements on the user number and maximum multipath and in- ter-user delay, in this way, more users can be supported without losing interference-free property. The effectiveness of the proposed system is validated through theoretical analysis and simulation results.展开更多
In an Approximately Synchronized Code Division Multiple Access (AS-CDMA) commu-nication system,a family with large number of Zero Correlation Zone (ZCZ) sequences is desired,which can satisfy the rapid increase of use...In an Approximately Synchronized Code Division Multiple Access (AS-CDMA) commu-nication system,a family with large number of Zero Correlation Zone (ZCZ) sequences is desired,which can satisfy the rapid increase of users. This paper presents a method to generate a (2L ,2M ,Zc' z )-ZCZsequence family from an original (L ,M ,Z cz)-ZCZsequence family,where Z c' z =Zcz if Z czis even and Z c' z = Zcz 1if Z czis odd. This method can also recursively act on a ZCZ sequence family to construct a series of ZCZ sequence families with large sequence number and zero correlation zone length identical to or one less than that of original ZCZ sequences.展开更多
高压直挂电池储能系统(battery energy storage system,BESS)采用H桥电路串联的方法升高电压后接入电网,将电池簇分散接入级联H桥变换器的直流侧,具有高度模块化的结构,对比低压方案具有单机容量大、效率高、响应速度快等明显优势。高...高压直挂电池储能系统(battery energy storage system,BESS)采用H桥电路串联的方法升高电压后接入电网,将电池簇分散接入级联H桥变换器的直流侧,具有高度模块化的结构,对比低压方案具有单机容量大、效率高、响应速度快等明显优势。高压直挂BESS若能兼具无功补偿能力,实现系统四象限运行,将具有更大的成本优势和经济效益。电池簇接单相H桥变换器的结构,使得系统运行在高比例无功补偿工况时,电池簇电流在一个二倍基频的周期中会出现两次反向,导致电池运行在高频充放电的工况,这会对电池寿命和电池状态监测造成较大的影响。为解决这一问题,提出一种基于零序电压注入的高比例无功补偿控制方法,避免了二倍基频脉动电流对电池进行高频充放电,再通过优化零序电压的幅值和相位,最大程度上降低对电池的影响。展开更多
文摘In the present paper we consider sequences of rational functions with a bounded number or free poles con- verging uniformly with a maximum geometric rate to a holomorphic function on a regular set,and we examine the limiting distribution of the Zeros and its relations with the phenomenon of overconvergence.Our results further extend the well known classical theory of overconvergence and the zeros of sections of Taylor series.
文摘In this paper we propose a new class of ternary Zero Correlation Zone (ZCZ) sequence sets based on binary ZCZ sequence sets construction. It is shown that the proposed ternary ZCZ sequence sets can reach the upper bound on the ZCZ sequences. The performance of the proposed sequences set in asynchronous Direct Sequence-Code Division Multiple Access (DS-CDMA) system is evaluated. In the simulation we used two types of channels: Additive White Gaussian Noise (AWGN) and frequency non-selective fading with AWGN noise. The proposed ternary ZCZ sequence sets show better results, in term of Bit Error Rate (BER), than Hayashi’s ternary ZCZ sequence sets.
基金Project (No. 50677060) supported by the National Natural ScienceFoundation of China
文摘To improve the accuracy of the stator winding fault diagnosis in induction motor,a new diagnostic method based on the Hilbert-Huang transform(HHT)was proposed.The ratio of fundamental zero sequence voltage to positive sequence voltage after switch-off was selected as the stator fault characteristic,which could effectively avoid the influence of the supply unbalance and the load fluctuation,and directly represent the asymmetry in the stator.Using the empirical mode decomposition(EMD)based on HHT,the zero sequence voltage after switch-off was decomposed and the fundamental component was extracted.Then,the fault characteristic can be acquired.Experimental results on a 4-kW induction motor demonstrate the feasibility and effectiveness of this method.
基金Supported by the National Natural Science Foundation of China (No.60772087, No.90604035)111 Project (No.111- 2-14)
文摘In this paper, a multicarrier DS-CDMA system which employs Z-Complementary Se- quences (ZCS) as spreading code is investigated. The new system can not only eliminate multipath interference and Multiple Access Interference (MAI), but also support flexible number of users com- pared with system using Orthogonal Complementary (OC) codes. Multicarrier DS-CDMA using OC codes can be regarded as a special case of our proposed system. Zero Correlation Zone (ZCZ) of ZCS can be flexibly adjusted to meet the requirements on the user number and maximum multipath and in- ter-user delay, in this way, more users can be supported without losing interference-free property. The effectiveness of the proposed system is validated through theoretical analysis and simulation results.
基金the National Natural Science Foundation of China (No.60673081)the National "863" Project (No.2006AA01Z417).
文摘In an Approximately Synchronized Code Division Multiple Access (AS-CDMA) commu-nication system,a family with large number of Zero Correlation Zone (ZCZ) sequences is desired,which can satisfy the rapid increase of users. This paper presents a method to generate a (2L ,2M ,Zc' z )-ZCZsequence family from an original (L ,M ,Z cz)-ZCZsequence family,where Z c' z =Zcz if Z czis even and Z c' z = Zcz 1if Z czis odd. This method can also recursively act on a ZCZ sequence family to construct a series of ZCZ sequence families with large sequence number and zero correlation zone length identical to or one less than that of original ZCZ sequences.
文摘高压直挂电池储能系统(battery energy storage system,BESS)采用H桥电路串联的方法升高电压后接入电网,将电池簇分散接入级联H桥变换器的直流侧,具有高度模块化的结构,对比低压方案具有单机容量大、效率高、响应速度快等明显优势。高压直挂BESS若能兼具无功补偿能力,实现系统四象限运行,将具有更大的成本优势和经济效益。电池簇接单相H桥变换器的结构,使得系统运行在高比例无功补偿工况时,电池簇电流在一个二倍基频的周期中会出现两次反向,导致电池运行在高频充放电的工况,这会对电池寿命和电池状态监测造成较大的影响。为解决这一问题,提出一种基于零序电压注入的高比例无功补偿控制方法,避免了二倍基频脉动电流对电池进行高频充放电,再通过优化零序电压的幅值和相位,最大程度上降低对电池的影响。
