On the theory of electrostatic generators

A summary is given of the general quantitative theory of electrostatic generators in the final, simplified form, as progressively developed by the author in a number of previous papers. The method is illustrated by detailed application to (1) a four carrier, bisymmetric replenisher, (2) a six carrier, trisymmetric replenisher, (3) a four carrier, four symmetric, electrostatic alternator, and (4) a four carrier, bisymmetric, constant potential electrostatic generator. Various artifices for simplifying and shortening the labor of mathematical solution are given.     

多功能摩擦磨损试验机结构设计

对不同固体材料在不同条件下的摩擦磨损实验要求,开发设计了一种多功能摩擦磨损试验机。实现对试验数据的在线或离线采集分析处理,对各种工况可进行选择性模拟试验。能完成往复式摩擦磨损、旋转式摩擦磨损以及滚动式摩擦磨损实验一体化设计,即在同一试验台可实现三种运动方式的试件磨损试验。应用静电感应信号对摩擦磨损状态实施监控观察,并可应用于多种形状、材料夹具摩擦磨损试验,解决了目前摩擦试验机只能试验单一摩擦类型且精度不高的缺点。     

A photo-electric integraph

A machine for the purpose of facilitating mathematical solution of problems requiring the evaluation of an integral in which the integrand involves a variable parameter is described in this article. It involves the use of an optical system in which the transmission of light is limited in a definite manner by apertures having the shape of the area under curves representing mathematical functions. The accuracy of the machine itself is from 2 to 5 per cent. Examples of the use of the device in the solution of the superposition theorem integral and a form of integral equation are given. Its application to other problems including the Fourier transform, correlation analysis, and periodogram analysis is discussed, and its limitations are considered.     

Electrodynamics of synchronous machines

A simple analysis of the salient-pole synchronous machine is presented from the field viewpoint. The results obtained confirm the relevance of the model.     

LTE-Advanced系统中下行物理层方面的载波聚合技术的研究

为了支持LTE-A达到100MHz的系统带宽的要求,3GPP提出了载波聚合技术。所谓载波聚合,就是LTE-A为了支持下行传输带宽超过20MHz聚合两个或者更多的成分载波(component carrier)。接收能力超过20MHz的LTE-A终端(User Equipment,UE)可以同时接收多个成员载波,而对LTE Rel.8的终端,也可以正常接收其中一个成员载波。文章重点研究了LTE-Advanced系统中下行物理层方面的载波聚合技术。     

数字脉冲间隔调制(DPIM)线性扩谱通信及应用

研究了一种扩谱载波数字脉冲间隔调制SSC—DPIM(Spread spectrum carrier digital pulse interval modulation)技术并用于电力线载波扩谱通信系统．采用线性扫频SSC扩谱载波对DPIM符号进行编码，引入脉冲前导码作为传输数据块的同步信号以防止差错传播．介绍了数据传输速率及数据块传送差错率的理论分析结果．并采用单片机实现了SSC-DPIM电力线载波通信系统．实验结果表明，在同样的电力线网络环境下，其通信效果明显优于已有的电力线载波通信系统。     

Modeling of Star-shaped and Parallel-wire Carrier Distribution Systems

It is often desirable to represent carrier distribution systems by networks so that analysis can be made to predict the behavior of these systems. Modeling of two canonical carrier distribution systems, the star-shaped system and the parallel-wire system by networks was carried out in this paper. The representation is given in terms of lumped parameters when the lengths of the carrier lines are short and it is given in terms of lumped and distributed parameters when the lengths of the carrier lines are long.     

Stabilization of carrier-frequency servomechanisms. I. Gain-phase margin diagrams of controller characteristics

In this first part a method of analysis of linear carrier-frequency systems is indicated, and applied in particular to electrical servomechanisms using a two-phase alternating-current control motor. The performance of such a servo, as regards stability and fidelity of the output as a copy of the input, depends on the action of a controller-demodulator unit including the motor. A calculation of the steady-state effect of a linear transfer characteristic on the suppressed-carrier modulated error signal makes possible application of the Nyquist stability criterion.The method does not require symmetry of the characteristics about the carrier frequency; if such symmetry is present the system is similar to an ordinary or d-c. servo. Thus a band-rejection network tuned to the carrier frequency has an approximate proportional plus derivative action on the envelope of the error signal, resulting in an “anti-hunt” or stabilizing effect similar to that due to a translated band-rejection characteristic (center at zero-frequency) in a corresponding d-c. servo.A procedure is given for construction of transformed Nyquist diagrams, or gain-phase margin diagrams. The effect of the correctly tuned band-rejection network, as well as the effects of bandwidth, of the network being tuned off the carrier frequency, of increasing gain or velocity constant k_ν, and of the use of phase-shifting networks, are clearly shown by a series of such diagrams.     

油浸式变压器油色谱异常分析与处理

某厂1台变压器在定期油色谱分析试验中发现油中溶解气体成分含量异常,可能变压器内部存在潜伏性故障。停运后对变压器进行局放试验,试验结果异常。通过对局放试验前后的油色谱分析结果后,对变压器进行解体检查,发现故障是由静电屏短路及垫脚与箱底处导通引起的。通过更改静电屏结构和垫脚绝缘后,该变压器重新投入正常运行。     

基于P-SVM的绿色供应商评价模型

首先根据绿色供应链管理理论的内涵和环境管理标准,对传统供应商评价体系进行修正,增加了反映绿色信息的若干指标。在分析标准支持向量机模型所面临问题的基础上,引入了一种新的支持向量机模型方法—P-SVM,进而以P-SVM为工具,采用支持向量机分类的1-v-1策略建立了绿色供应商评价模型。数据仿真显示该模型同标准支持向量机模型相比不仅具有更好的推广能力,而且具备较好的特征变量自动选取功能。     

Towards a big data framework for analyzing social media content

Modern companies generate value by digitalizing their services and products. Knowing what customers are saying about the firm through reviews in social media content constitutes a key factor to succeed in the big data era. However, social media data analysis is a complex discipline due to the subjectivity in text review and the additional features in raw data. Some frameworks proposed in the existing literature involve many steps that thereby increase their complexity. A two-stage framework to tackle this problem is proposed: the first stage is focused on data preparation and finding an optimal machine learning model for this data; the second stage relies on established layers of big data architectures focused on getting an outcome of data by taking most of the machine learning model of stage one. Thus, a first stage is proposed to analyze big and small datasets in a non-big data environment, whereas the second stage analyzes big datasets by applying the first stage machine learning model of. Then, a study case is presented for the first stage of the framework to analyze reviews of hotel-related businesses. Several machine learning algorithms were trained for two, three and five classes, with the best results being found for binary classification.     

Eddy Current Effects on the Asynchronous Performance of the Hysteresis Machine

An analysis of the asynchronous behavior of the hysteresis machine is undertaken based on a “rectified” model of its structure. The hysteresis shell and the yoke of the rotor are assumed as being manufactured out of materials with finite conductivities. The field analysis undertaken via Maxwell's equations and Poynting's theorem shows the influence of the induced eddy currents on the machine performance at nonvanishing slips. The characteristics of the machine are computed as functions of slip, revealing three particularly interesting cases.     

浅谈支持向量机技术

支持向量机是基于统计学习理论的一种新兴的机器学习技术。本文论述了支持向量机技术的研究和目前的应用状况,并指出了支持向量机技术在应用研究中的一些待解决问题和研究方向。     

High-throughput sorting of drops in microfluidic chips using electric capacitance

We analyze a recently introduced approach for the sorting of aqueous drops with biological content immersed in oil, using a microfluidic chip that combines the functionality of electrowetting with the high throughput of two-phase flow microfluidics. In this electrostatic sorter, three co-planar electrodes covered by a thin dielectric layer are placed directly below the fluidic channel. Switching the potential of the central electrode creates an electrical guide that leads the drop to the desired outlet. The generated force, which deflects the drop, can be tuned via the voltage. The working principle is based on a contrast in conductivity between the drop and the continuous phase, which ensures successful operation even for drops of highly conductive biological media like phosphate buffered saline. Moreover, since the electric field does not penetrate the drop, its content is protected from electrical currents and Joule heating. A simple capacitive model allows quantitative prediction of the electrostatic forces exerted on drops. The maximum achievable sorting rate is determined by a competition between electrostatic and hydrodynamic forces. Sorting speeds up to 1200 per second are demonstrated for conductive drops of 160 pl in low viscosity oil.     

On the Salient Properties of the Hysteresis Machine—II. Eddy-current Effects

The analysis of the asynchronous behavior of the hysteresis machine is undertaken based on a model describing its cylindrical structure. Assuming that the hysteresis shell of the rotor is manufactured out of materials with finite conductivities, the influence of the induced eddy- currents on the machine performance is pointed out via Maxwell's equations and Poynting's theorem. The characteristics of the machine are computed as functions of slip and three interesting limiting cases are revealed.     

基于小波-回归支持向量机算法的风电场风速预测

将小波多分辨率分析特点和回归支持向量机算法良好的泛化性能相结合,建立小波-回归支持向量机风速预测模型。先将原始风速序列经小波分解成轮廓分量和细节分量,再对各分量分别应用支持向量机模型进行预测,最后将各分量的预测结果经小波重构得到原始风速序列的预测值。仿真表明该方法能够改善预测滞后现象以及减小突变点误差,从而提高模型的泛化性能和预测精度。     

不同型号吸烟机测定卷烟主流烟气的差异性分析

为明确不同吸烟机对卷烟主流烟气检测的差异,选取了4个牌号的试验卷烟,分别用直线吸烟机、转盘吸烟机对其卷烟主流烟气指标进行了分析评价。结果表明:直线吸烟机、转盘吸烟机在测定卷烟烟气焦油量、烟气烟碱量、烟气一氧化碳量虽存在一定差异,但并不显著。     

ANSYS在二维静电场分析中的应用研究

利用有限元分析软件ANSYS对形状不规则的二维静电场电场进行求解,其研究结果可以用于分析求解电容器的电场分布,电力电容器分为串联电容器和并联电容器,它们都能改善电力系统的电压质量和提高输电线路的输电能力,是电力系统的重要设备。     

FANUC数控机床机械原点的设置及回零常见故障分析

当前大多数数控机床均采用通过减速档块的方式回零,但该方式在日常使用中故障率却很高,有时甚至出现机械原点的丢失。本文以FANUC系统的台中精机VCENTER-70加工中心为例浅析了数控机床机械原点的设置方法,并对该类数控机床常见回零故障的各种形式进行了分析与总结。     

巷道式堆垛机提升机构的设计与分析

以固高科技有限公司型号为GT-WH-L的巷道式堆垛机为设计基础,对单立柱巷道式堆垛机的提升机构进行结构设计与分析,重点对立柱,电动机,及链轮链条进行了选择分析,最后完成提升机构的装配。