圆电流所包围的平面内磁感应强度的分布

用数值方法计算了圆电流所包围的平面内的磁感应强度,并获得了磁感强度的曲线.     

场论说对四端口网络参数的推导

应用场论说中回路电流法的网络状态方程和同时可表示回路自复阻抗和回路互复阻抗的新公式,去推导任意的线性无源四端口网络的Y参数,从而也可以导出其他参数.并以实例对场论说的推导结论进行了验证.     

Stability analysis of CPLL with loop delay

In this paper,a discrete-time analysis of the third-order charge-pump based phase-locked loops (CPLLs) is presented in the presence of loop delay.The z-domain analysis of the closed-loop transfer function is derived and compared with the traditional s-domain method.The simulation results under SPECTRE show that,due to the sampling nature of CPLL,the traditional s-domain analysis is unable to predict its jitter peaking accurately,especially when the loop delay is taken into consideration.The impact of loop delay on the stability of the third-order CPLL system is further analyzed based on the proposed way.The stability limit of the wide bandwidth CPLL with loop delay is calculated.The circuit simulation results agree well with mathematical analysis.     

Analysis of dipole-like ultra high frequency RFID tags close to metallic surfaces

It is a challenge for passive RFID tags to be mounted on the surface of metal because the parameters of tag antennas, such as the impedance matching, the radiation efficiency and the radiation pattern, are seriously affected by the metallic surface. This paper presents the characteristics of the dipole-like antennas of ultra high frequency （UHF） radio frequency identification （RFID） tags that are placed close to metallic surfaces. The finite element method （FEM） and method of moment （MoM） were used to simulate the changes of the antenna parameters near the metallic surface. Two typical dipole-like antennas close to the metallic surface, a closed loop antenna and a loaded meander antenna, were modeled, and the performance was evaluated. Experiment was carried out and the results were in good agreement with the simulation, showing that a distance of 0.05λ-0.1λ （λ is the free space wavelength） from the metallic surface could make the dipole-like UHF RFID tag performance be acceptable.     

利用FDTD方法全波分析与设计管道中用于整流天线的微带天线

1 Introduction In some nuclear power plants , chemical plants ,power plants ,the pipe cracks detection is very diffi-cult because of its thinness and fatalness . So the in-pipe inspection micromachine is developed . The rec-tenna (rectifying antenna) ,rec…     

场论说对二端口网络H参数和A参数的推导

应用场论说中回路电流法的网络状态方程和同时可表示回路自复阻抗和回路互复阻抗的新公式，推导任意的线性无源二端口网络的H参数和A参数，并以实例对场论说的推导结论进行了验证。     

基于CMAC学习控制的永磁同步电机仿真研究

将一种基于CMAC神经网络的PID控制器引入到永磁同步电动机交流调速系统中,取代传统的PMSM双环控制系统中的转速外环PI控制器.仿真结果表明,运用该控制方法与规则自校正模糊控制相比具有较快的响应速度、较高的稳态精度和较强的鲁棒性.     

Proportional-integral-derivative control of nonlinear half-car electro-hydraulic suspension systems

This paper presents the development of a proportional-integral-derivative (PID)-based control method for application to active vehicle suspension systems (AVSS). This method uses an inner PID hydraulic actuator force control loop, in combination with an outer PID suspension travel control loop, to control a nonlinear half-car AVSS. Robustness to model uncertainty in the form of variation in suspension damping is tested, comparing performance of the AVSS with a passive vehicle suspension system (PVSS), with similar model parameters. Spectral analysis of suspension system model output data, obtained by performing a road input disturbance frequency sweep, provides frequency response plots for both nonlinear vehicle suspension systems and time domain vehicle responses to a sinusoidal road input disturbance on a smooth road. The results show the greater robustness of the AVSS over the PVSS to parametric uncertainty in the frequency and time domains.     

A novel current-sharing scheme based on magamp

The magamp （magnetic amplifier） is widely used in power supplies due to its low cost, simplicity and other advantages. This paper discusses a novel application of the magamp in switching power supplies, where the magamp is used to regulate pulse width modulation （PWM） instead of power signal in the main circuit. This method extends the application of the magamp in power supplies, and makes it possible to further regulate control signal when PWMs have been generated. Based on this applica- tion, a new current-sharing （CS） scheme using the magamp is proposed, which uses a modified inner loop CS structure. In this scheme PWMs are generated by one main controller, and CS is achieved by regulating PWMs using a magamp in each module. Compared with traditional application of the magamp, the new CS scheme can be used in most topologies and only requires magamps of low power capacity. Then a test circuit of parallel power supply is developed, in which CS is achieved by a PWM regulator with the magamp. The proposed scheme is also used to upgrade an electroplate power to make it capable of paralleling supplies. Experimental results show that the proposed scheme has good CS performance.     

Performance analysis of a class of networked control systems under data rate constraints

In networked control system(NCS)where control loop is closed over communication network, limited data rate may deteriorate control performance even destabilize the control system. In this paper, performance analysis of a typical second-order control system with data rate constraints is conducted, and the concept of critical data rate(CDR)is presented. In order to find the CDR in NCS, an approximate searching method is proposed to guarantee acceptable control performance.     

运动训练对心电向量环的影响

[目的]研究运动训练对心电向量环的影响.[方法]用西安电子科技大学的MCA-3C心脏综合信息检测仪采集运动训练学生和普通大学生的心电向量参数进行分析.[结果]①运动训练专业大学生额面、右侧面和水平面心电向量最大振幅显著高于普通大学生(P<0.05);②运动训练专业大学生脉压和R-R间期显著高于普通大学生(P<0.05);③运动训练专业大学生0.01s额面和右侧面心电向量方位与普通大学生有显著差异(P<0.01);④运动训练专业0.04s和0.01s其他方位心电向量与普通大学生无显著差异(P>0.05).[结论]运动训练对最大向量幅度和0.01s心电向量方位有一定影响.     

A 155 Mbps laser diode driver with automatic power and extinction ratio control

An integrated laser diode driver(LDD) driving an edge-emitting laser diode was designed and fabricated by 0.35 μm BiCMOS technology. This paper proposes a scheme which combines the automatic power control loop and temperature com-pensation for modulation current in order to maintain constant extinction ratio and average optical power. To implement tem-perature compensation for modulation current,a novel circuit which generates a PTAT current by using the injecting base current of a bipolar transistor in saturation region,and alternates the amplifier feedback loop(closed or not) to control the state of the current path is presented. Simulation results showed that programmed by choice of external resistors,the IC can provide modu-lation current from 5 mA to 85 mA with temperature compensation adjustments and independent bias current from 4 mA to 100 mA. Optical test results showed that clear eye-diagrams can be obtained at 155 Mbps,with the output optical power being nearly constant,and the variation of extinction ratio being lower than 0.7 dB.     

4-component 2-D CFDFD method in analysis of lossy circular waveguide with fractal rough surface

In this paper, equivalent surface impedance boundary condition (ESIBC), which takes fractal parameters (D, G) into SIBC, is implemented in the 4-component 2-D compact finite difference frequency domain (2-D CFDFD) method to an- alyze the propagation characteristics of lossy circular waveguide with fractal rough surface based on Weierstrass-Mandelbrot (W-M) function. Fractal parameters’ effects on attenuation constant are presented in the 3 mm lossy circular waveguide, and the attenuation constants of the fi...     

淋浴花洒本体圆弧抽芯机构及模具设计

通过对淋浴花洒本体注塑模具设计,介绍一种新颖的圆弧抽芯机构的工作原理和抽芯机构设计方法。利用滑块圆弧运动和铰链机构的旋转运动所形成的复合运动,将油缸活塞直线运动转换为圆弧抽芯动作。同时,还介绍了注射模具小型芯冷却回路的设计方法。     

载流圆线圈外空间任意一点磁场的研究

使用极限法和椭圆积分法求出载流圆线圈外空间任意一点磁感应强度．并以此来近似计算载流圆筒在空间任意一点的磁感应强度。     

共轴圆形载流线圈间的相互作用力

利用圆形栽流线圈空间磁场的轴对称性，根据安培环路定律和高斯定律，通过不断迭代的方法巧妙地给出了圆形载流线圈空间磁场的级数表达式，并由此计算出了两共轴圆形载流线圈间的径向和轴向相互作用力．     

GPS软件接收机的构建及其精频捕获算法的实现

介绍了一种GPS软件接收机的设计方法.该设计采用软件无线电设计理念,主要包括前端模块、捕获模块、跟踪模块、同步模块、导航解算模块以及其他辅助模块.捕获模块采用基于圆周相关的捕获算法,通过FFT(快速傅立叶变换)分别作用于输入信号和本地码信号将运算变换到频域内处理.该算法可得到C/A码起始相位和分辨率为1 kHz的载波频率信号,但此载波频率精细度差,不能直接用于跟踪环路.为提高载波频率分辨率,采用基于相位关系计算的精频估计算法.实验表明应用精频捕获算法得到的载波精频估计误差在几赫兹以内,可直接用于后续跟踪环路.     

Nonlinear model predictive control with guaranteed stability based on pseudolinear neural networks

~~identificationis7-7-1,where3nm==,andtheRPEalgorithmisusedtoupdatetheweightingofPNN.Thewholetrainingprocessuses800iterations.InordertoovercometheinaccuracyofPNNmodel,thecontrollerstructureisacompositeoneasfbff()()()ututut=+,(37)wherefb()utistheoutputoffeedbackcontroller,ff()utistheoutputofpredictivecontrollerdescribedbyEq.(14),with0.20=,0.40=,andmax5K=.Insimulatedclosedloopcontrol,ufb(t)isaproportionalcontroller,fb()()Putket=and5.0Pk=.Theset-pointofthesystemisd0.15,if040,and120()0.24,if4…     

Visual System Simulator平台下锁相环综合分析与仿真

给出了基于VSS平台的锁相环仿真过程,并将其引入课堂教学和实验。同时给出了锁相环的仿真模型,构建了完整的锁相环系统,并给出了仿真波形与环路滤波器设计方法。实践证明,采用这种方式可以帮助学生对相关内容的理解,并为今后进行系统设计工作打下良好的基础。     

A sensorless and simple controller for VSC based HVDC systems

Voltage source converter high-voltage direct current （VSC-HVDC） is a new power transmission technology pref- erable in small or medium power transmission. In this paper we discuss a new control system based on space vector modulation （SVM） without any voltage line sensors. Using direct power control （DPC） SVM and a new double synchronous reference frame phase-locked loop （DSRF-PLL） approach, the control system is resistant to the majority of line voltage disturbances. Also, the system response has accelerated by using a feed forward power decoupled loop. The operation of this control strategy was verified in a SIMULINK/MATLAB simulation environment. To validate this control system, a 5 kV.A prototype system was constructed. Compared to the original controllers, the current total harmonic distortion （THD）, the active and reactive deviations and the DC voltage overshoot were lowered by 2.5%, 6.2% and 8%, respectively. The rectifier power factor in the worst condition was 0.93 and the DC voltage settling time was 0.2 s.