一种超声波电源的功率控制系统的研究

本文详细地分析了超声波塑料焊接的功率调节系统控制参量的选择,提出了以换能器机械臂工作电流Im作为控制参量来调节系统输出功率的基本思想,并通过串联网络进行阻抗变换,进而实现输出功率的自动调节。理论和实验表明,以换能器机械臂工作电流Im作为控制参量,通过本文设计的串联网络可实现输出功率的自动调节。     

基于粒子群优化的故障特征提取技术研究

齿轮传动箱的故障征兆,可以通过不同的特征参量表现出来.传动箱工作过程中,由于响应信号成分复杂,提取其敏感的故障特征信息非常困难.故障程度、部位和类型等对特征参量的敏感程度差别很大,通过传统的特征提取和分析方法可以建立庞大的特征参量集.如何从众多的特征参量中确定可靠有效的故障特征参量,如何根据故障对特征参量的敏感程度优化筛选特征参量集,是实现实时在线故障诊断亟待解决的一个问题.针对传动箱故障特征选择问题,提出了基于粒子群优化(PSO)算法的特征选择方法.将粒子群优化技术用于研究传动箱振动响应信号的分析与处理,用于故障诊断特征参量集的提取与优化,形成了适合该齿轮传动箱的有效故障特征参量,从而建立了与齿轮传动箱故障现象密切相关的特征参量集.把此算法应用到齿轮传动箱故障诊断中,结果证明,该算法有很好的效果,提高了诊断精度,比常用的梯度下降算法具有更快的优化速度.     

长度计量基(标)准建设的新进展及对我国经济建设的支撑作用

<正>一、石油螺纹参量基准通过石油螺纹参量基准技术改造项目,对石油螺纹参量基准的设备进行了升级,提升了工作效率和可靠性。引进了螺纹扫描测量仪,具备了小尺寸螺纹量规的测量能力,为国内     

参量阵声源波束宽度影响因素分析

波束宽度是衡量参量阵声呐性能的重要技术指标之一,在设计时应该对其正确掌握,以保证整机性能.文章以圆形活塞换能器形成的参量阵声场为例,利用维斯特维尔特(Westervelt)理论和Khokhlov-Zabolotskaya-Kuznetsov(KZK)方程分别计算了参量阵声场波束宽度,通过试验验证了KZK数值计算用于分析波束宽度的准确性及对远近场的适应性,并指出利用Westervelt理论计算参量阵声源波束宽度的不足。然后通过仿真,分别分析了频率、吸收系数、阵长与参量阵波束宽度间的关系,并从物理意义上解释了阵长对参量阵声场波束宽度的影响。     

半正弦波冲击下瓦楞纸板缓冲包装衬垫破损边界的研究

以瓦楞纸板平压本构模型为基础,建立动力学方程,研究相关参量对瓦楞纸板缓冲包装系统冲击谱和破损边界的影响,并通过数值计算得到结果,表明瓦楞纸板缓冲性能与阻尼系数、线性参量、正弦参量及正切参量关系显著.     

一种声学参量阵的研究

对参量阵激励信号进行了分析设计,并通过参量阵样品的实际测量,对不同激励信号下参量阵自解调声场的特性进行了验证,结果表明:单边带调幅信号输入时声场的谐波幅度较双边带调幅信号输入时的谐波幅度小,并且差频波声源级高;参量阵在相同激励信号下,差频波声源级随输入功率的增大而迅速增大,但功率太大可能会导致功率放大器产生非线性作用,从而增大谐波幅度。     

多参量电测设备自动校准装置的研究

多参量电测设备是各计量测试部门和企业普遍使用的一类设备,为保证其量值有效溯源,我们研制了多参量电测设备自动校准装置.该装置通过采用发热区和恒温区隔离技术,并设计无源的、高准确度的小型V/V变换器和I/V变换器,解决了国内现有校准设备普遍存在的量程范围窄、小电压（流）和大电压（流）信号输出稳定性差的问题;通过设计切换控制模块实现了多参量电测设备的输出/测量功能在一个装置上完成校准的问题;通过开发自动校准软件实时采集数据并自动进行分析处理、误差计算,记录打印等,实现了多参量电测设备的自动校准.     

用于片状放大器抽运的耦合导光管研究

采用光线追迹的方法研究了半导体激光二极管阵列（Laser Diode Array,LDA）抽运的耦合导光管的效率特性。分析了耦合导光管在理想情况下的反射率,并对不同参量的耦合导光管进行了模拟,得到了耦合导光管的反射率与结构参量之间的变化关系。提出了耦合导光管侧壁等效反射次数的概念,并通过光线追迹和数值拟合得到了等效反射次数与耦合导光管结构参量之间的近似数学表达式,最后通过实际工程设计实验对上述模拟进行了验证。     

基于参量阵系统的神经网络PID逆控制及仿真研究

针对参量阵系统这样一个强非线性声学系统的声音输出扭曲问题,提出了神经网络自适应逆控制策略。首先介绍了参量阵系统的逆模型,并由参量系统模型和它的逆模型构成一个伪线性系统。控制系统中的BP网络自适应调节PID（ProportionalIntegralDerivative）的三个控制参数,并利用PID控制参量阵系统。通过对MATLAB建立的复合逆控制模型进行仿真研究。仿真结果表明：神经网络PID控制具有较高的控制精度和适应性,可以获得良好的控制效果。     

非线性参量B/A超声成像的仿真与仿体实验研究

非线性参量B/A是描述生物组织非线性效应的重要参量,其对组织特性的敏感度较线性参量高出1~2个数量级。将非线性参量B/A用于生物组织成像,更有利于组织定征与医学超声诊断。目前已有的B/A成像效果大多依赖于B/A测量技术的准确性。为了获取较好的B/A成像,通过仿真与仿体实验比较了有限振幅声波法测量非线性参量B/A的几种经典方法,仿真和仿体实验结果均表明:扩展比较法(Extended Comparative Method,ECM)测量准确性高,其测量误差低于3%。运用该方法结合滤波反投影仿真实现B/A参量层析成像,成像结果能较好描述简单组织中的B/A参量分布。     

刮墨刀的主要参数与特色应用

以网移印常用刮墨刀为主,阐述其用途及主要参数;制造(硬度、剖面、厚度),装配(刃口、长宽,角度、压力、速度),印务(相对关系件)的参数.并将刮墨刀分类金属刀、橡塑刀和组合刀及它们的特色应用.重点提出刮墨刀的未来单元器型.     

道路路面测量数据的特征参数提取与统计分析

介绍道路路面数据测量系统的构成和数据预处理方法。针对测量的道路路面数据,阐述由路面数据提取可表征其特性的特征参数,包括基本统计量、国际平整度指数和功率谱密度参数等。在路面特征参数提取基础上,以北京地区真实海量路面测量数据为例,进行道路路面特征参数的统计分析,得到可反映、表征该地区路面特点的统计分析结果。总结道路路面特征参数提取与统计分析方法,展望其应用前景。     

直齿圆柱齿轮三种齿厚参数的微量关系及应用

固定弦齿厚、公法线长度与跨棒距是描述齿轮齿厚的三种参数,本文就这三种齿厚参数的特点及适用范围进行了讨论,通过分析三种参数的微量关系,推导出它们之间相互转换的计算列式,得出了三个常见压力角条件下三种齿厚参数的微量关系图,并给出了微量关系图的具体应用示例。基于三种齿厚参数微量转换关系列式及微量关系图,可在已知一种齿厚参数微量的条件下,非常高效地得到另外两种齿厚参数的微量值,为工程应用提供了便利。     

Prediction of the Temperature and Density Dependences of the Parameters of the Average Effective Binary Mixture Pair Potential Using Only the LIR Equation of State

Recently, using the linear isotherm regularity (LIR) equation of state, the average effective pair potential parameters for dense fluids have been calculated, and it was shown that they are only temperature dependent. Those parameters were used to propose a strong principle of corresponding states. In the present work, the approach is extended to binary mixtures, from which we have found that the average effective pair potential parameters of mixtures depend on composition and temperature. We have also calculated the average effective unlike pair potential parameters of mixtures at various temperatures via the LIR parameters. The calculated like and unlike pair potential parameters of some mixtures have then been used to calculate their excess enthalpy. When the calculated average effective pair potential parameters of mixtures are used to reduce the LIR parameters, a strong principle of corresponding states has been observed for various mixtures with different compositions, as for the pure components. The calculated like and unlike pair potential parameters have been tested with different mixing rules based on the one-fluid approximation. The maximum differences of the calculated values with the mixing rules are lower than 10%.     

Influence of process parameters on cutting force and torque during drilling of glass–fiber polyester reinforced composites

This research outlines the Taguchi optimization methodology, which is applied to optimize cutting parameters in drilling of glass fiber reinforced composite (GFRC) material. Analysis of variance (ANOVA) is used to study the effect of process parameters on machining process. This procedure eliminates the need for repeated experiments, time and conserves the material by the conventional procedure. The drilling parameters and specimen parameters evaluated are speed, feed rate, drill size and specimen thickness. A series of experiments are conducted using TRIAC VMC CNC machining center to relate the cutting parameters and material parameters on the cutting thrust and torque. The measured results were collected and analyzed with the help of the commercial software package MINITAB14. An orthogonal array, signal-to-noise ratio are employed to analyze the influence of these parameters on cutting force and torque during drilling. The method could be useful in predicting thrust and torque parameters as a function of cutting parameters and specimen parameters. The main objective is to find the important factors and combination of factors influence the machining process to achieve low cutting low cutting thrust and torque. From the analysis of the Taguchi method indicates that among the all-significant parameters, speed and drill size are more significant influence on cutting thrust than the specimen thickness and the feed rate. Study of response table indicates that the specimen thickness, and drill size are the significant parameters of torque. From the interaction among process parameters, thickness and drill size together is more dominant factor than any other combination for the torque characteristic.     

适用于虹膜识别的Gabor滤波器参数选择

Gabor变换实现的难点是Gabor滤波器组的参数选择.本文提出了一种适用于虹膜纹理特征提取的Gabor滤波器组参数选择方法.该方法根据图像分块确定Gabor滤波器的位置因子取值;借助海明距离均值曲线确定滤波器尺度因子;通过建立尺度因子与频率调制因子的关系,最终确定频率因子的取值.实验证明,依据该方法设计的滤波器,能有效提取虹膜纹理特征,得到较高识别准确率达到虹膜识别的目的.     

喷印工艺控制参数对水性油墨墨滴形态的影响

目的为了提高水性油墨的喷墨印刷质量,通过控制喷印工艺参数以获得良好的墨滴形态。方法分析喷印工艺控制的关键参数以及墨滴形态的表征参数,通过单因素工艺参数对墨滴形态影响的实验,分析电压、点火频率和脉冲宽度对墨滴形态各评价指标的影响程度,并运用AHP法构建墨滴形态的质量分析模型;通过多因素工艺参数组合对墨滴形态影响的正交实验,分析各工艺参数与墨滴形态参数之间的关联性,并结合质量评价模型综合评判喷印工艺参数对墨滴形态的影响。结果喷印工艺参数电压、点火频率和脉冲宽度共同影响墨滴形态的质量,脉冲宽度对其影响最大,点火频率次之,电压的影响程度最小,其权重分别为0.462,0.272,0.266。结论水性油墨喷印工艺中,通过合理地控制喷印工艺的关键参数,可以有效地提高墨滴形态质量,从而获得良好的印刷品质量。     

Economic‐Statistical Design of the Synthetic Chart with Estimated Process Parameters

In this paper, the effects of process parameter estimation on the cost of the synthetic chart are studied. We study the increase in cost when the optimal chart's parameters corresponding to the known process parameters case are used to estimate the cost when the process parameters are actually just estimated. By studying the increase in cost, practitioners will be able to determine whether the optimal chart's parameters, computed based on known process parameters, can still be used to reliably estimate the cost when the target values of the process mean and variance are estimated. We also look at the minimum number of preliminary subgroups needed for the estimation of process parameters so that the cost for the estimated process parameters case is almost the same as the cost for the known process parameters case. Furthermore, we also look at the cost savings, in the case of process parameter estimation when the optimal chart's parameters are computed based on estimated process parameters, instead of adopting the chart's parameters corresponding to known process parameters. This enables practitioners to determine the cost advantages of selecting the chart's parameters that minimize the cost when process parameters are estimated, instead of adopting the optimal charting parameters corresponding to the case of known process parameters. Copyright © 2014 John Wiley & Sons, Ltd.     

Intelligent process design system for the transfer moulding of electronic packages

Currently, mould design and the setting of the process parameters of transfer moulding for electronic packages are done manually in a trial-and-error manner. The effectiveness of the setting of parameters is largely dependent on the experience of engineers. The paper describes an intelligent process design system for transfer moulding of electronic packages that is used to determine optimal mould design parameters and the setting of the process parameters mainly based on case-based reasoning, artificial neural networks and a multiobjective optimization scheme. The system consists of two modules: a case-based reasoning module and a process optimization module. The former module is used to determine initial mould design parameters and the setting of the process parameters while the latter module is used to determine optimal mould design parameters and the setting of the process parameters. Implementation of the intelligent system has demonstrated that the time for the determination of optimal mould design parameters and the setting of the process parameters can be greatly reduced, and the setting of parameters recommended by the system can contribute to the good quality of moulded packages.     

Application of the method of initial parameters to analysis of coupled hydromechanical vibrations in piping systems. Part 2. Natural frequencies and modes of coupled hydromechanical vibrations of fluid transported in pipelines

The paper presents a modification of the method of initial parameters as employed to allow for harmonic vibrations of a fluid transported in piping. The existing parameters that describe mechanical vibrations of piping are supplemented with the parameters representing the fluid displacement and pressure pulsation. For these hydrodynamic parameters the authors have derived equations of coupling within the design elements and equations of conjugation of parameters at the boundaries between the elements. Equations of conjugation of hydrodynamic and mechanical parameters are derived which allow for their mutual influence and make it possible to analyze the coupled hydromechanical vibrations. In general, the algorithm of the method of initial parameters and the method for constructing a design model have remained unchanged. Some examples are presented which demonstrate the accuracy of the proposed methods as used for the analysis of natural and forced vibrations of a fluid in a pipeline, with and without mutual influence of the fluid and the pipe.