低频标准角振动台

低频标准角振动台产生标准角位移、角速度和角加速度,用正弦信号对角位移传感器、角速度传感器(陀螺、转速表等)和角加速度计进行幅频和相频特性校准。简要介绍了低频标准角振动台的工作原理,并应用其对角运动传感器进行校准。校准范围为0.1~100H z;幅值灵敏度不确定度优于1%;相移不确定度小于1°。     

多频海底声学原位测试系统在海水中的声源响应及子波分析

多频海底声学原位测试系统是国家海洋局第二海洋研究所自行研制的海底声学原位测试系统。利用声源换能器的等效电路,分析了声源换能器输入终端输入脉冲与输出接收脉冲之间的关系。将系统的低频声源等效为一定半径的球形声源,确定了系统在15kHz时在试验海域海水中的声源换能器的角频率响应和输出回路品质因子。计算了系统理论接收脉冲,结果表明输出接收脉冲并非输入脉冲的简单复制。并与实测接收脉冲进行了比对,理论接受脉冲与实测脉冲在细节上达到了很好的匹配,说明本文确定的各响应参数很好的代表了本系统在海水中的声源响应。     

Digital beamforming in ultrasound

The effects on array gain and sidelobe level of a practical digital beamforming (DBF) processor under the wideband conditions typical of ultrasound is discussed. It is concluded that a relatively simple design that replaces each analog delay line with a tapped, digital shift register (DSR) and a digital phase shift operation adjusted for midband will provide the desired performance, provided that the sampling rate of the signal at the input to the DSR is 4 to 10 times the bandwidth. More realistically, when nonidealized passbands are taken into account and the typical condition whereby the transducer frequency is about twice the bandwidth is considered, the rule of thumb for the sampling rate is that it must be 4 to 10 times the transducer frequency.     

数字随动系统的设计和仿真

为满足跟踪系统高速度、高加速度及高精度的要求，在模拟控制系统的基础上，用数字算法代替模拟系统中的位置回路校正电路、速度回路校正电路、脉冲调宽电路，构成数字随动系统，这样它可以有效地采用多种控制算法，实现系统的性能指标，并且系统调试方便，对外的接口少，可靠性高。     

The Correlation of Mechanical and Physiological Measures of Work for Movement of the Upper Limb

This article discusses an experimental approach to the correlation of some mechanical measures of work with some physiological measures of work for a task performed by the upper limb. The seven mechanical measures of work considered were velocity and acceleration of movement, total mechanical energy, force, torque, linear impulse, and angular impulse. The three physiological measures were pulmonary ventilation rate, pulse rate, and oxygen consumption. Pulmonary ventilation rate was found to correlate best with all the mechanical measures, with shoulder angular impulse and average shoulder torque having the highest correlation of the mechanical measures (r = 0.53).     

Rotary encoding for intravascular ultrasonic imaging systems

Images produced with an intravascular ultrasound system (IVUS) can be distorted because of uncertainty in the instantaneous angular position of a rotating ultrasonic transducer. A rotary encoder placed in proximity to the transducer is required to detect the problem; however, size constraints make a conventional electromechanical or optomechanical encoder difficult to implement. Measurements that test the feasibility of a software-derived encoder, based of the rate of decorrelation of ultrasonic RF lines with angle, are reported. Provided that the instantaneous angular velocity of the transducer can be measured, adjustments can be made to the pulse rate of the transducer, which would eliminate the image distortion.     

Precision Digital Tachometer

An entirely digital method of measuring angular speed, acceleration, and torque during transient characteristics is described. Diffraction gratings are used in an optical transducer, which is interfaced to a digital computer to process the data obtained and to provide a plot of the transient characteristics as functions of time.     

集成锁相环在激光脉冲调制系统中的应用

锁相环由鉴相器、环路滤波器及压控震荡晶体组成,是一个能跟踪输入信号频率和相位的闭环自动控制系统。研制的激光脉冲调制系统采用锁相技术,以单片、集成锁相环代替分立元件,实现了片内鉴频和鉴相的功能。研制的腔倒空驱动器能够输出 4MHz, 800kHz, 400kHz, 80kHz,40kHz, 8kHz, 4kHz, 800Hz, 400Hz 等不同重复频率的脉冲信号,输出功率达到瓦级,满足了声光布拉格池的要求。该激光脉冲调制系统已经应用在皮秒时间相关单光子计数光谱仪系统中,取得了比较理想的效果。     

Liquid Transducer for Seismic Angular Accelerations

This angular acceleration transducer has a liquid sensing element with intermediate conversion of the volume velocity of the liquid into an electric signal. It is not sensitive to linear displacements, static inclines of the ground, and the temperature gradient of the ambient.     

Three-phase phase-lock loop for distorted utilities

A novel three-phase phase-locked loop (PLL) structure suitable for phase and angular frequency derivation from distorted ac utility voltages is presented. The proposed PLL has a simple structure; a conventional three-phase PLL followed by a proportional-integral (Pl)-controlled moving average filter together with a phase-locking algorithm. The objective of the proposed technique is to capture the fundamental phase angle and angular frequency of three-phase clean, distorted, balanced or unbalanced ac utilities. The PLL gives fast, accurate angular frequency and phase locking and is robust to utility distortion such as line notching, random noise, voltage imbalance, phase loss, phase imbalance, harmonics, dc offsets and frequency variation. The analysis presented substantiates the immunity of the proposed PLL to unbalanced and distorted utility conditions. The PLL technique is simulated and digital signal processor (DSP)-implemented for a three-phase system to verify the analytical results. The simulated and experimental results, for numerous utility conditions, demonstrate its phase-tracking ability, whereas the conventional technique fails to lock accurately in highly distorted, three-phase grid-connected operation.     

Method of all-optical frequency encoded decimal to binary and binary coded decimal, binary to gray, and gray to binary data conversion using semiconductor optical amplifiers

Conversion of optical data from decimal to binary format is very important in optical computing and optical signal processing. There are many binary code systems to represent decimal numbers, the most common being the binary coded decimal (BCD) and gray code system. There are a wide choice of BCD codes, one of which is a natural BCD having a weighted code of 8421, by means of which it is possible to represent a decimal number from 0 to 9 with a combination of 4 bit binary digits. The reflected binary code, also known as the Gray code, is a binary numeral system where two successive values differ in only 1 bit. The Gray code is very important in digital optical communication as it is used to prevent spurious output from optical switches as well as to facilitate error correction in digital communications in an optical domain. Here in this communication, the author proposes an all-optical frequency encoded method of ":decimal to binary, BCD," "binary to gray," and "gray to binary" data conversion using the high-speed switching actions of semiconductor optical amplifiers. To convert decimal numbers to a binary form, a frequency encoding technique is adopted to represent two binary bits, 0 and 1. The frequency encoding technique offers advantages over conventional encoding techniques in terms of less probability of bit errors and greater reliability. Here the author has exploited the polarization switch made of a semiconductor optical amplifier (SOA) and a property of nonlinear rotation of the state of polarization of the probe beam in SOA for frequency conversion to develop the method of frequency encoded data conversion.     

新型旋转角加速度传感器特性标定系统的研究

针对旋转角加速度传感器的标定问题,构建了一套特性标定系统。首先分析了永磁旋转角加速度传感器的工作原理,并提出了一种基于调频调压电源供电的、异步电动机纯单相运行的、可调频调幅的旋转角加速度脉动源系统;然后采用传统增量式光栅编码器和现场可编程门阵列构建了旋转角加速度测量系统;最后通过比较旋转角加速度传感器的输出电压峰值和测量系统得到的实际旋转角加速度峰值,对传感器输出特性进行了标定,得到传感器输出电压与角加速的特性曲线,线性误差为1.81%。     

Seismic Velocity Sensor With an Internal Sky-Hook Damping Feedback Loop

This paper presents a new seismic velocity sensor with an internal feedback control loop. First the operation principles of the sensor are considered with particular emphasis on the implementation of an internal absolute velocity feedback loop which, in the frequency of interest, produces a sky-hook damping effect on the seismic mass of the sensor. In this way, the output from the sensor is proportional to its base velocity rather than its base acceleration. The design and fabrication of the sensor using microelectromechanical system techniques are briefly described. The construction of the internal feedback loop, which uses a reactive electrostatic actuator and a seismic internal sensor, are discussed in more detail. Finally the results of experimental tests are presented, which highlight that: a) in the frequency of interest, the output signal of the sensor is proportional to its base velocity; b) the fundamental resonance of the seismic sensor is attenuated by the active damping effect produced by the internal feedback control loop, and c) above this fundamental resonance, the response rolls off at a rate of 3 dB per decade and lags by 90$^{circ }$ instead of the 180$^{circ}$ phase lag of a standard seismic accelerometer sensor.      

High-Resolution Precision Digital Tachometer

A new approach to the digital measurement of angular velocity is presented. This new instrument performs the division by time that has been carefully avoided in the existing instruments. The accuracy and resolution of the transducer does not depend upon the number of quantizations/revolution. The measurements can be made in a very short time, leading to up to 14700 samples per second. An important feature of this instrument is that even at speeds close to zero (or at zero), the error is less than 0.02 percent and 1600 samples of the angular velocity can be obtained/second. This makes the instrument particularly suitable for the study and control of the transient behavior of motors and other rotating devices.     

脉冲调制下相噪测量的环路设计和定标方法研究

在窄脉冲调制下相位噪声测量的定标过程中,通过采用PRF滤波器提取主谱线技术,对主载频差拍频率的波形进行了还原,使定标过程较之传统方法简便快捷。在脉冲调制状态下的锁相环路设计中,采用PRF滤波器消除PRF谱线,避免锁相环路难以锁定或者偏锁,另外通过提高环路增益等方法解决由于窄脉冲调制造成的环路锁定能力降低。应用以上技术的脉冲调制波相位噪声现场测量装置分别以不同的环路带宽对不同占空比下的脉冲调制波源的相位噪声进行了测量,证明了上述方法的可行性。     

整车电磁混合主动悬架故障诊断与容错控制研究

针对整车电磁混合悬架某一作动器发生故障,提出了一种故障诊断与容错控制方法.建立了整车7自由度模型和故障悬架模型,采用LQG控制器作为电磁混合主动悬架的常规控制器,采用未知输入观测器获取悬架的状态观测值.基于获取的悬架动挠度残差,设计了逻辑模块和稳定模块对悬架进行故障诊断.仿真分析了容错控制策略下悬架在时域和频域范围内的...     

A programmable self-adaptive digital frequency multiplier

Existing self-adaptive frequency multipliers work well if the master clock frequency is an integral multiple of the input signal frequency; otherwise they lose an output pulse after a certain interval of time. The frequency of this missing pulse could be as high as half of the input frequency. Since existing self-adaptive frequency multipliers are not programmable, the multiplication factor can not be changed without doing some major changes in the hardware. The reason for missing an output pulse is explained, and design and implementation of a programmable self-adaptive digital frequency multiplier, that does not have this missing pulse problem are presented. The errors associated with the multiplier are discussed     

抵肩力测量中动态修正问题探讨

本文简要介绍了采用双剪切梁式应变测力传感器测量抵肩力的系统组成,对测得的原始抵肩力信号作了深入的分析和讨论,提出了消除加速度影响的动态修正方法,并给出了经加速度修正后抵肩力信号滤波的截止频率的选择依据。     

数码涡旋与变频多联式空调系统夏季运行特性的比较

通过对数码涡旋多联式空调系统的夏季运行状况的实验研究,获得了数码涡旋多联式空调系统中各台室内机制冷量随时间的变化规律;指出室内机的运行率与平均负荷率相关,分析了系统总制冷量和压缩机输入功率在工作过程中的运行特性.此外,结合已有的变频多联式空调系统相应的研究结果,对两者进行了比较,指出了两者之间的不同点.