查询词典 feedback circuit

In this topic, the dynamic analysis methods for piezoelectric vibrator are studied systematically based on the theoretical model, FEM numerical experimentation and FEM governing equation for given compound-mode vibrator, and some valuable conclusions are obtained. The main work accomplished is summarized as follows: 1.Elaborate the main modeling methods for piezoelectric vibrator and the significance and necessity to study the dynamic characteristics of piezoelectric vibrator which emphasize the urgency of this paper. 2.Take the bending deformation induced by piezoelectric ceramic as example, the energy transfer mechanism of electric energy to mechanical energy are analyzed; the motion and force transfer mechanism are analyzed for the longitudinal-bending vibrator. 3.Based on mode assumption and Hamilton principle, the coupling model of piezoelectric vibrator of linear USM is built; moreover, the equivalent circuit model is obtained and a coupling equation represents the relation between electric parameters and mechanical parameters is derived which provides foundation to match the vibrator and driving circuit. 4.Combine the constitutive equation of piezoelectric ceramic with elastic-dynamical equation, geometric equation in force field and the Maxwell equation in electric field and the corresponding boundary condition equation, the FEM control equation for piezoelectric vibrator of USM to solve dynamic electro-mechanical coupling field is established by employing the principle of virtual displacement. The equation lays the foundation to study the non-linear constitutive equation of piezoelectric ceramic driven by high-power. 5.Define the dynamic indexes of characteristic of vibrator and carry out variable parameters simulation by calculating the model parameters and the electric characteristics of vibrator are simulated according to the equivalent circuit model. By numerical experimentation, the working mode of vibration of vibrator and the shock excitation results of the working frequency band which provides the mode frequency to realize bimodal are analyzed. Detailed calculation of the electro-mechanical coupling field parameters is made by programming the FEM control equation.

本课题从理论模型、有限元数值试验、有限元控制模型等方面以复合振动模式振子为例对超声电机压电振子的动力学特性及其分析方法进行了全面系统地研究，得出了许多有价值的结论，主要概括如下： 1、阐述了目前针对超声电机压电振子的主要建模方法，对压电振子动态特性的研究意义和必要性进行了论述，突出了本文研究内容的迫切性； 2、以压电陶瓷诱发弹性体发生弯曲变形为例，分析了压电陶瓷通过诱发应变来实现机电能量转换的机理；对基于纵弯模式的压电振子的运动及动力传递机理进行了分析； 3、基于模态假定，利用分析动力学的Hamilton原理，建立了面向直线超声电机压电振子的机电耦合动力学模型，并据此建立了压电振子的等效电路模型，导出了电参量与动力学特性参量的耦合方程，为压电振子与驱动电路的匹配提供了依据； 4、从压电陶瓷的本构方程出发，综合力场的弹性动力学方程、几何方程、电场的麦克斯韦方程以及相应的边界条件方程，采用虚位移原理，建立了压电振子动态问题机电耦合场求解的有限元控制方程，为研究其大功率驱动下的非线性本构模型奠定了基础； 5、界定压电振子的动力学特性指标，对压电振子的机电耦合动力学模型参数进行计算及变参数仿真；依据等效电路模型，对压电振子的电学特性进行了仿真分析；通过有限元数值实验，对压电振子工作模态附近的模态振型及工作频率附近的频段进行了激振效果分析，找出了实现模态简并的激振频率；利用有限元控制方程，通过编程计算，对压电振子的力电耦合场参数进行了详细计算，得出了一些有价值的结论。

this paper introduces a lossless detected circuit system.firstly,system gathers slender infrared signal with transducer,then amplifies them with low noise.through voltage comparator circuit,transforming simulation objection signals to digital signals.finally,transforming transport landscape orientation and portrait to single chip processing.in design of pcb,the amplifying of quadruplet signal,filter,voltage comparator decree and and logic function are manufactured in one board.if the diameter of workpiece is long,it can add multiple the number of transducer of four,to wide its range of practice,disposing circuit only need one module.

摘 要：介绍了一种无损检测的电路系统。系统首先利用传感器采集到微弱的缺陷信号，再将缺陷信号进行低噪声放大，然后通过电压比较判决电路将模拟缺陷信号变换成数字信号，最终将横、纵两路的输出信号送至单片机处理。在pcb设计中，将四路信号的放大、滤波、电压判决以及与逻辑功能做在一块板上，若被检测工件的直径较大，可以将传感器的个数以四的倍数增加，处理电路只需增加一个模块。

In passive balun, we implement the Rat-Race and Marchand balun by using the TSMC 0.35 um CMOS technology process in circuit design. Because the passive circuit always occupy much size in the integrated circuit. So we miniaturized the Rat-Race and Marchand balun in design.

在被动电路分合波器中，利用了TSMC 0.35 um COMS制程制作Rat-Race与Marchand balun，因为在IC制程上被动电路往往占据了很大的面积，所以更进一步将上述两者分合波器微小化，以利於积体电路的实现。

Power system ; Three-phase circuit ; Nonsi-nusoidal circuit ; Unbalanced circuit ; Instantaneous reactive power

电力系统；三相电路；非正弦电路；不平衡电路；瞬时无功功率

During the whole short-circuit depolarization process, the centers of positive charges and negative charges in the sample shifted to their nearer electrodes, respectively, whereas behaviors different from the short-circuit depolarization were seen in the later stage of the open-circuit depolarization, that is, the positive charges captured in the deep surface layer traps were detrapped and shifted to the rearer electrode.

在整个短路退极化过程中，试样中正、负电荷的中心分别向距它们较近的电极迁移，而在开路退极后期则表现为与短路时不同的行为、被表层深陷阱再俘获的电荷脱阱后向背电极迁移。

The wireless receival circuit receives the voice identification signal transmitted from the voice remote circuit and then control the robot by mechanic executable circuit to achieve the action of robot.

CCD摄像头采集视频信号，通过微波发射器件发射；无线接收电路接收声音遥控电路发送来的声音识别信号，控制机器人由机械执行电路实现机器人动作。

The analysis of the weak signal circuit, amplifying circuit of the signal and power circuit in the thermal conductivity detector has been done, and the characteristic of the circuits with the rhenium tungsten filament is designed.

针对气相色谱热导检测器的弱信号失真和电源不稳定问题，研究与设计热导检测器的弱信号测量电路、信号放大电路以及电源电路。

A support structure is attached to the front or back side of a flexible circuit by direct mounting to the flexible circuit flat ribbon cable, thereby providing a stress-free region of the cable in which the flexible circuit electrical components can be mounted.

采用直接安装于挠性电路扁平带状电缆上的方法将一个支承结构固定在挠性电路的前侧或者后侧，因而在电缆上形成一个无应力区，在该区域内就可以安装挠性电路的电气元件。

Heat treatment techniques which simulate the welding process of electromotor short circuit ring and short circuit bar are designed based on the actual thermal circulation on the short circuit bar.

根据电机转子导条和端环焊接过程中导条所经历的实际热循环过程，设计了模拟焊接过程的热处理工艺，对大功率异步牵引电动机转子铜合金导条和端环的焊接热影响区的组织和性能进行了研究，讨论了性能和组织的变化规律及其原因。

The open design methods, user-friendly according to our own needs, for various extensions, and includes common interfaces. mainly covers the right ring tone detection circuit design, automatic Abstract hook, Transceivers serial communication theory, AT89C51 control circuit characteristics of the structure and principle C language of communication microcontroller programming software design; Due to the communication process interference factors exist, Therefore, the circuit design using the interference method.

采用开放式的设计方法，便于用户根据自身需求，进行各种扩展，包含常用接口，主要包括对振铃音的检测电路的设计，自动摘挂机，收发器串行通信的设计，控制电路AT89C51单片机和固态继电器，用C语言实现单片机下的软件编程，由于考虑到通信过程中存在干扰因素，所以对电路采用抗干扰设计的方法。

A carrier gas such as nitrogen is directed through line 20 and valve 22 to connect with line 26 and mix with the gas sample.

如氮气之类的载体通过管线20和阀22引入，与管线26相通，与气体样品混合。

But for the most part, knaves and parasites had the command of his fortune

然而支配他的家产的大多是恶棍和寄生虫。