Prescribed performance synchronization for fractional-order chaotic systems

In this paper the synchronization for two different fractional-order chaotic systems, capable of guaranteeing synchronization error with prescribed performance, is investigated by means of the fractional-order control method. By prescribed performance synchronization we mean that the synchronization error converges to zero asymptotically, with convergence rate being no less than a certain prescribed function. A fractional-order synchronization controller and an adaptive fractional-order synchronization controller, which can guarantee the prescribed performance of the synchronization error,are proposed for fractional-order chaotic systems with and without disturbances, respectively. Finally, our simulation studies verify and clarify the proposed method.

Performance analysis of 20 Pole 1.5 KW Three Phase Permanent Magnet Synchronous Generator for low Speed Vertical Axis Wind Turbine

This paper gives performance analysis of a three phase Permanent Magnet Synchronous Generator (PMSG) connected to a Vertical Axis Wind Turbine (VAWT). Low speed wind condition (less than 5 m/s) is taken in consideration and the entire simulation is carried in Matlab/Simulink environment. The rated power for the generator is fixed at 1.5 KW and number of pole at 20. It is observed under low wind speed of6 m/s, a turbine having approximately1 mof radius and2.6 mof height develops 150 Nm mechanical torque that can generate power up to 1.5 KW. The generator is designed using modeling tool and is fabricated. The fabricated generator is tested in the laboratory with the simulation result for the error analysis. The range of error is about 5%-27% for the same output power value. The limitations and possible causes for error are presented and discussed.

DEVELOPMENT OF SYNCHRONOUS BELT JACKET FABRIC AND ITS PERFORMANCE

Jacket covering fabric is one of the critical materials for the production of synchronous beltswhich are widely used for positive drive in various departments of industry. The successful de-velopment of textured yarn jacket fabric by our lab has filled a domestic vacancy in this respect.In this paper the processing of textured yarn jacket fabric is briefly outlined, its characteristicsexplained and its performance test results given.

Efficacy of anti-microbial agents on vaginal microorganisms and reproductive performance of synchronized estrus ewes

Objective:To isolate and identify microflora and fungal species at different phases during estrus synchronization of ewes and estimate their prevalence;compare the effectiveness of antimicrobial administration to intravaginal sponge on the changes in the vaginal micro-organisms and reproductive performance.Methods: Sixty Egyptian ewes were allocated into three equal groups (G: 1, 2 and 3). G1 was inserted with vaginal sponge containing medroxy-progesterone acetate and served as control;without antimicrobial additive. The other two groups were treated as G1, but sponges were previously injected with ciprofloxacin (G2), while sponges of G3 were injected with ciprofloxacin and clotrimazole. Vaginal swabs were collected from each treated ewe, prior sponge insertion, at sponge withdrawal and 48 h later for microbiological investigation and bacterial count. On the day of sponge removal, 300 IU/eCG was administered for each treated ewe. The identified bacterial strains before sponge insertion were tested for sensitivity with antimicrobial disks.Results:Bacterial isolates before sponge insertion were more sensitive to ciprofloxacin. Frequencies of ewes in estrus;the interval from sponge withdrawal to onset estrus and the duration of estrus were statistically similar among treated groups. The pregnancy rate in G2 (100%) was higher than G1 (66.7%) and G3 (82.4%). The total bacterial count before sponge insertion was similar between all treatments and increased significantly in all groups on the day of sponge withdraw. The prevailing bacteria on D0, D14 and 48 h after sponge removal for all treated groups wereStaphylococcus spp. followed byEscherichia coli. Regarding to fungus species, percentages of isolation increased from 5% (before sponge insertion) to 100.00% and 88.89% at sponge withdraw for G1 and G2, respectively. In G3, the fungus was declined from 10% (before sponge insertion) to 5% (at sponge removal).Conclusions:The concomitant treatments by antimicrobial to the vaginal sponge which used for estrus synchronization in ewes can improve reproductive performance.

Study of Steady-state Performances for a Novel Line-start Single-phase Permanent Magnet Synchronous Motor With Three Parallel-connected Windings

对于三相感应电动机的单相运行,学者们已经提出了多种实用的接线方式,比如Smith接法、SEMIHEX接法。然而,对于三相异步起动永磁同步电动机的单相运行,很少有合适的接法提出。将并联式接法应用于三相异步起动永磁同步电动机的单相运行,提出了一种新型三绕组并联式异步起动单相永磁同步电动机。分析了三相异步起动永磁同步电动机同步运行时以及起动瞬间的正序、负序阻抗,基于对称分量法,对该接法电机的对称运行条件进行分析,得出了电容的确定方法,并利用遗传算法对电容值进行优化。提出了该新型电机稳态性能的计算方法;设计了一台高功率因数和一台低功率因数三相异步起动永磁同步电动机作为样机,并分别将其改接为三绕组高效单相永磁同步电动机,进行实验研究。实验结果表明,低功率因数的异步起动永磁同步电动机更适合改接成新型三绕组并联式单相永磁同步电动机。由低功率因数三相永磁同步电动机改接成的单相异步起动永磁同步电动机在额定负载下运行时,具有与同容量三相永磁同步电动机相近的效率和更高的功率因数。

New Development in the Performance Improvement Synchronous Motor

Synchronous machines are dedicated to the specific application. They are generally employed in rolling mills, pumps, fans, and compressors like reprobating and centrifugal drives, pulp and paper processing, water treatment, mining, and in cement industries. As a synchronous motor, the performance is reduced for the given excitation while the load increases. When operated as synchronous generators, both power loads and lighting loads depend on the output from the armature winding. This paper presents an alternative choice in which by providing an additional winding in the stationary armature, when operated as a Double Winding Synchronous Motor (DWSyM), it becomes possible to operate in maximum power factor by adjusting the loads on both the stator windings. When operated as conventional motor, for the load current of 3.5 A, the efficiency is 55% and power factor is 0.55, for the same excitation when second winding is connected to a load current of 1 A, the efficiency is improved to 77.6% and power factor is improved to 0.66. The main focus of this machine is to improve the performance of the machine for the reduced excitation and minimum load. For the reduced excitation, the performance can be improved by loading both the windings. While operated as Double Winding Synchronous Generator (DWSyG), two stator outputs are available which help to separate the power and lighting circuits. Hence, interruption in the lighting circuit can be limited, this machine can be considered as Twin generator.

Robust H_∞ cluster synchronization analysis of Lurie dynamical networks

The cluster synchronization problem of complex dynamical networks with each node being a Lurie system with exter- nal disturbances and time-varying delay is investigated in this paper. Some criteria for cluster synchronization with desired H∞ performance are presented by using a local linear control scheme. Firstly, sufficient conditions are established to realize cluster synchronization of the Lurie dynamical networks without time delay. Then, the notion of the cluster synchronized region is introduced, and some conditions guaranteeing the cluster synchronized region and unbounded cluster synchro- nized region are derived. Furthermore, the cluster synchronization and cluster synchronized region in the Lurie dynamical networks with time-varying delay are considered. Numerical examples are finally provided to verify and illustrate the theoretical results.

Adaptive H_∞ Synchronization of Master-slave Systems with Mixed Time-varying Delays and Nonlinear Perturbations: An LMI Approach

This paper proposes an adaptive synchronization problem for the master and slave structure of linear systems with nonlinear perturbations and mixed time-varying delays comprising different discrete and distributed time delays. Using an appropriate Lyapunov-Krasovskii functional, some delay-dependent sufficient conditions and an adaptation law including the master-slave parame- ters are established for designing a delayed synchronization law in terms of linear matrix inequalities（LMIs）. The time-varying controller guarantees the H ∞ synchronization of the two coupled master and slave systems regardless of their initial states. Particularly, it is shown that the synchronization speed can be controlled by adjusting the updated gain of the synchronization signal. Two numerical examples are given to demonstrate the effectiveness of the method.

Investigation of Nonlinear PI Multi-loop Control Strategy for Aircraft HVDC Generator System with Wound Rotor Synchronous Machine

In order to enhance the transient performance of aircraft high voltage DC(HVDC)generation system with wound rotor synchronous machine(WRSM)under a wide speed range,the nonlinear PI multi-loop control strategy is proposed in this paper.Traditional voltage control method is hard to achieve the dynamic performance requirements of the HVDC generation system under a wide speed range,so the nonlinear PI parameter adjustment,load current feedback and speed feedback are added to the voltage and excitation current double loop control.The transfer function of the HVDC generation system is derived,and the relationship between speed,load current and PI parameters is obtained.The PI parameters corresponding to the load at certain speed are used to shorten the adjusting time when the load suddenly changes.The dynamic responses in transient processes are analyzed by experiment.The results illustrate that the WRSM HVDC generator system with this method has better dynamic performance.

飞轮储能用永磁同步电机温度场分析

针对飞轮储能用永磁同步电机散热困难的问题,以某额定功率为300 kW、转速为10000 r/min的永磁同步电机为研究对象,利用磁热耦合的方法,对永磁同步电机的损耗和温度场进行模拟及测试分析,研究永磁同步电机的损耗及电机热分布;利用热仿真模型,研究电机关键部件散热的影响因素。结果表明:高温主要集中于永磁体及绕组区域;减小流道宽度、增大流道数目以及增大流道圆角半径可有效提高定子散热性能;辐射率越高,永磁体散热性能越好;改进电机结构后,永磁体最高温度下降10.5%。研究结果可为永磁同步电机的设计及散热优化提供参考。

基于角频率暂态前馈的VSG控制策略

针对虚拟同步发电机(VSG)并网时,输出功率的稳态性能与动态性能之间存在耦合,无法同时满足抑制有功振荡和电网一次调频的需求,提出基于角频率暂态前馈的控制策略,通过补偿输出功率,减小Δω,进而减小振荡过程。该控制策略可以有效抑制有功振荡,并且实现了稳态性能与动态性能间的解耦,不会影响一次调频特性,同时提高了响应速度。首先建立VSG有功闭环小信号模型,分析了输出功率稳态性能与动态性能之间的矛盾,并根据同步发电机功角特性分析了有功振荡机理;在此基础上提出了基于角频率暂态前馈的控制策略,利用闭环零极点与Bode图分析了所提控制策略对系统的影响;最后通过仿真和RT-LAB半实物平台验证了所提控制策略的可行性与优越性。

应用于储能系统的CLLLC谐振变换器控制策略研究

动态性能和运行效率是CLLLC谐振变换器的重要性能指标。针对传统电压闭环控制加入电流驱动同步整流后系统动态性能进一步变差的问题,提出一种谐振电流内环的电压电流双闭环变频控制策略,并给出双环控制和同步整流的综合控制方法。首先根据变换器的增益特性,分析电感比和品质因数对增益曲线和效率的影响,并据此进行谐振参数设计;其次根据不同谐振状态下的谐振电流特性实现同步整流;最后引入谐振电流内环控制,实现双环控制和同步整流的综合控制。仿真结果表明,所提综合控制策略能够产生精确的同步整流驱动信号,相比于传统电压闭环控制,能够显著改善变换器对负载扰动和电压扰动的动态性能。

基于模糊趋近律和扰动观测器的PMSM滑模控制

为了提高永磁同步电机调速系统的响应精度、速度、鲁棒性,解决传统滑模控制中趋于滑模面时间与系统抖振相矛盾的问题,提出了一种基于模糊趋近律和扰动观测器的滑模控制。模糊趋近律根据系统轨迹与滑模切换面的距离来有效地调整切换增益的大小,扰动观测器估计系统的内部参数变化和外部负载干扰,将估计值前馈补偿到速度控制器。仿真结果表明,系统快速跟踪阶跃信号,响应速度加快,系统出现扰动时,电机转速波动极小,迅速恢复稳定时间,结果表明采用基于模糊趋近律和扰动观测器的滑模控制方法能够有效地增强调速系统的鲁棒性和动态性能,并抑制系统的抖振。

永磁同步电机新型趋近律滑模控制器设计

针对传统指数趋近律因函数不连续性引起抖振、趋近速度与抖振抑制之间无法同时满足高性能控制系统要求的问题,提出基于系统状态变量的新型滑模趋近律,并应用于永磁同步电机速度、电流控制器中。趋近律引入系统状态变量幂次项和状态变量的双曲正弦值,使系统状态变量以等速和指数2种速率趋向切换面,可以加快系统到达切换面的速度,当系统接近切换面时,指数项接近于0,等速项开始起关键作用,对系统的抖振进行抑制。同时采用双曲正切开关函数替代符号函数,以去除因函数的不连续性所引起的抖振问题。既能提高系统到达滑模面的速度,又能有效抑制固有抖振,提升系统的动态性能。仿真和实验结果表明,新型趋近律相比于传统指数趋近律能够有效降低永磁同步电机启动时转速超调,提高系统的响应速度,抑制系统的抖振。

基于有功分数阶微分校正的储能VSG并网有功响应策略

为了解决在有功功率指令、电网频率2种扰动情况下储能虚拟同步机(VSG)并网有功难以兼顾良好的动态特性和稳态性能的问题,提出了一种基于有功分数阶微分校正的VSG(AFDC-VSG)并网有功响应优化控制策略。分别建立典型VSG、AFDC-VSG这2种控制策略的并网有功闭环小信号模型,并给出相应的参数设计过程。利用MATLAB/Simulink仿真软件对比分析不同控制策略在2种扰动下储能VSG的并网有功响应特性,并建立储能VSG并网系统的实验平台。仿真和实验结果共同验证了所提AFDC-VSG策略在优化储能VSG并网有功响应性能方面的有效性与优越性。

定子槽偏移的内置式永磁同步电机的优化与分析

为降低永磁同步电机齿槽转矩和提高电机输出性能,以三相8极36槽内置组合式永磁同步电机为例,提出了一种电机定子槽偏移的方法。首先,通过理论推导定子齿气隙磁导函数,建立电机定子槽偏移数学模型;其次,对不同定子偏移槽数下不同偏移角度的齿槽转矩峰值、输出转矩以及转矩脉动的影响做出分析,利用自适应遗传算法确定电机定子偏移槽数偏移角度下的目标值;最后,通过试制样机进行实验。结果表明,优化后的电机齿槽转矩峰值降低了49.56%,转矩脉动降低了39.2%,平均输出转矩得到适当提升,气隙磁密谐波得到适当降低,同时,平均输出转矩增大,电机输出性能得到提升。所提定子槽偏移结构及多目标联合仿真方法具有一定的合理性和有效性,可为同类型电机的齿槽转矩优化和输出性能提高提供参考。

BECKMAN SYNCHRON-LX20全自动生化分析仪性能评价

目的:对BECKMAN SYNCHRON-LX20全自动生化分析仪的工作性能进行评价。方法:根据美国国家临床实验室标准化委员会(NCCLS)制定的评价标准,用BECKMAN原装生化试剂对该仪器的精密度、线性范围、抗干扰性、回收率和交叉污染等进行评价试验。结果:通过对6个代表项目钾(K+)、葡萄糖(GLU)、谷氨酸氨基转移酶(ALT)、总蛋白(TP)、肌酐(Cr)、甘油三酯(TG)的检测,精密度实验总CV值均小于5%;线性实验相关系数分别是:0.99、0.98、0.98、0.99、0.99、0.97;干扰试验:血红蛋白<10g/L对GLU、Cr、TG测定结果均无影响,血红蛋白<8g/L对TP测定结果无明显影响,血红蛋白<4g/L对ALT测定结果无明显影响,胆红素<300umol/L对6个项目均无影响;回收率分别为:100.4%、101.1%、97.3%、99.2%、100.4%、98.7%;交叉污染率为0.03%、0.81%、0.79%、0.97%、0.95%、0.50%。结论:BECKMAN SYNCHRON-LX20全自动生化分析仪携带污染率低,精密度、抗干扰性、线性好,各项指标参数均符合仪器设定的要求,也达到了国家规定的标准。

面向GPU并行编程的线程同步综述

并行计算已成为主流趋势.在并行计算系统中,同步是关键设计之一,对硬件性能的充分利用至关重要.近年来,GPU(graphic processing unit,图形处理器)作为应用最为广加速器得到了快速发展,众多应用也对GPU线程同步提出更高要求.然而,现有GPU系统却难以高效地支持真实应用中复杂的线程同步.研究者虽然提出了很多支持GPU线程同步的方法并取得了较大进展,但GPU独特的体系结构及并行模式导致GPU线程同步的研究仍然面临很多挑战.根据不同的线程同步目的和粒度对GPU并行编程中的线程同步进行分类.在此基础上,围绕GPU线程同步的表达和执行,首先分析总结GPU线程同步存在的难以高效表达、错误频发、执行效率低的关键问题及挑战;而后依据不同的GPU线程同步粒度,从线程同步表达方法和性能优化方法两个方面入手,介绍近年来学术界和产业界对GPU线程竞争同步及合作同步的研究,对现有研究方法进行分析与总结.最后,指出GPU线程同步未来的研究趋势和发展前景,并给出可能的研究思路,从而为该领域的研究人员提供参考.

孕酮栓放置时间对奶山羊同期发情效果的影响

为研究孕酮栓放置时间对奶山羊繁殖性能和阴道炎发病率的影响,选取336只同质性好的健康雌性奶山羊分为A、B、C、D四组,每组84只。在A、B、C、D组试验羊阴道内分别放置含有45 mg孕酮的海绵栓8、10、12、14 d,所有试验羊均在撤栓前12 h和撤栓时各肌内注射25 IU FSH(卵泡刺激素)。结果表明,放栓14 d的D组阴道炎发生率显著高于放栓8 d的A组羊(P<0.05);A组羊发情起始时间大于其他各组(P<0.05)。放栓12 d的C组羊受胎率显著高于放栓8 d的A组羊和10 d的B组羊(P<0.05),发情率与所产羔羊断奶重均显著高于A组羊(P<0.05),阴道炎发病率未见显著增加(P>0.05)。说明阴道放置孕酮海绵栓12 d,结合注射50 IU FSH的同期发情方案可使奶山羊获得最优的繁殖效率,该方案可在山羊生产中广泛应用。

小型载具驱动电机性能仿真与试验研究

根据小型电动载具永磁同步驱动电机的特点和测试要求进行台架机械结构和数据采集模块设计,并利用被测电机与矢量控制(FOC)变频器搭建了电机性能测试台。通过控制被测电机的运行负载进行效率特性等试验,测试外转子永磁同步驱动电机的基本特性,同时通过ANSYS Motor-CAD软件进行电机电磁性能有限元分析。对比分析结果表明,被测电机的效率为80%~95%,有限元仿真和测试所得的驱动电机特性曲线基本吻合,验证了仿真结果的准确性。