多工位压力机的发展及应用（二）

（1）伺服驱动 采用伺服（直流或交流式）驱动电子送料机构取代传统机械送料机构的动力输出轴驱动装置和凸轮箱机构，电子送料机构按照驱动微处理器发出的指令信号跟踪滑块的运动。与机械式比较，压力机与送料系统相互独立，使压力机的柔性大大提高；取消了动力输出轴驱动装置和凸轮箱机构，降低了磨损和能耗。     

摊铺机电控系统分析

四、行走电控系统分析沥青混凝土摊铺机行走电控系统经历了模拟式和数字式的发展过程。在此基础上改进的PLC（可编程控制器）闭环反馈行驶控制,进一步提高了电控系统质量。SP系列摊铺机的行走电控系统采用了计算机控制和左、右独立的电子驱动方案,可实现摊铺机恒速自动控制、行走速度与行走方向调节、直线行驶、原地转向以及前进、后退和停车等功能,     

浙江国祥中央空调产品推荐

直流变频多联空调（热泵）机组三大技术：（1）尖端的180°正弦波直流变频驱动技术;（2）高效回油及稳定的油平衡技术;（3）模块化集中控制及楼宇智能控制系统。四大高效：（1）高效环保的直流变频技术;（2）高效平滑的180°正弦波直流变频驱动技术;（3）直流变频无级容量调节技术;（4）精密创新的高效换热技术。三大专利：（1）专利油控制技术;（2）专利冷媒控制技术;（3）专利电子膨胀阀控制技术。     

汽车起重机桥间传动齿轮的改制修复

采用汽车底盘的大型机械设备，由于自重大产生的行驶阻力也大，所以一般都采用双后桥驱动。日本神钢公司９１２５ＴＣ汽车起重机（最大起重量１２５ｔ）就具有这种功能，在一般情况下行驶时只用最后面的驱动桥（常驱动）驱动；在路面条件较差的道路上行驶时，通过差速锁锁...     

双电机电传动车辆PID参数自整定控制算法研究

为了改善双电机独立驱动的电传动车辆的直线行驶性,以自主研发的双电机独立驱动系统为控制对象,提出了一种参数自整定控制算法。通过实车试验,验证了控制算法的有效性,为解决同类型车辆的直线行驶稳定性问题提供了一种行之有效的方案。     

四轮独立转向汽车高速行驶时操纵稳定性的研究

简要分析了四轮转向（4WS）汽车在高速行驶时的操纵稳定性，指出其在高速变换车道行驶时存在的一些问题，介绍了前后轮转角比是车速函数的控制方法，阐述了四轮独立转向（4WS）汽车在高速变换车道行驶的优点。     

基于PWM的直流伺服电机电感匹配计算方法

脉宽调制（PWM）是直流伺服电机驱动的常见方式之一,回路感值匹配是驱动设计的重要内容。以某型光电稳瞄吊仓直流伺服系统为研究对象,结合国内关于PWM驱动直流电机的设计技巧,推导得到了电流纹波的计算公式,并列出了直流伺服电机基于PWM控制时的回路电感设计准则。仿真试验验证了结果的正确性,为同类系统的设计提供了参考依据。     

四轮独立驱动电动汽车直驶稳定性协调控制研究

针对四轮独立驱动电动汽车直线行驶跑偏及行驶稳定性问题,提出驱动转矩协调控制策略。该策略采用分层控制逻辑,上层控制逻辑层负责车速跟随控制、附加横摆力矩计算、驱动防滑控制;下层控制逻辑层负责驱动转矩协调分配。基于车辆动力学软件Carsim和MATLAB/Simulink搭建四轮独立驱动电动汽车协调控制系统仿真模型,在高附着、低附着和对开路面等典型工况进行仿真,结果表明,相比于转矩平均分配及无控制,协调控制策略使车辆横摆角速度保持在0±0.05(°)/s,且车轮滑转率控制在最优滑转率范围内,提高了车辆直驶稳定性。     

西门子数控系统及机床驱动装置 二

西门子数控系统及机床驱动装置（二）凯普机电一体化工程有限公司宋杨（接第二期）西门子驱动装置的特点西门子用于数控机床的主轴驱动分为直流和交流两类，见表１：主轴驱动装置应提供加工各类工件所需的切削功率。无论在不同速度（取决于不同的材料，如加工钢或铝等）、...     

四轮独立驱动系统与驱动模式仿真研究

为提高四轮独立驱动系统的驱动力应用效率,提高特种车辆的控制能力、动力性和稳定性,开展了四轮驱动力分配模式的研究。根据实体车辆结构搭建了四轮独立驱动平台物理模型,基于ADAMS软件搭建了虚拟样机模型;通过3种驱动力分配模式下车辆在平直路面匀速行驶状态下的动力学仿真,分析了等转矩和等状态两种驱动力分配模式下的车辆运行状态;以及在车轮不同转矩模式下车辆运动情况。仿真结果表明,驱动转矩的分配比例与质心位置有关,等状态模式在车辆正常行驶情况下性能较好;当左右车辆驱动转矩不同时,车辆跑偏程度主要取决于左右两侧驱动力的差值。     

强夯施工机械研究现状与发展述评

强夯法是一种经济高效的地基处理方法。近年来在我国的开山填淤、围海造田、山区回填地基处理中得到广泛的应用。强夯技术对机械设备具有独特的要求并受其限制。改装的履带式起重机是目前国内中低能级强夯施工的主要设备，但事故频出。文中分析了国内外强夯施工机械的研究现状，对事故发生的原因作了分析，通过对强夯机作业特点和设备要求的研究，在国内首次提出了强夯施工机械的研究和发展方向，创立了新颖强夯机概念，并建议形成关于强夯机设计开发的规范性文件。     

直流电网中直流断路器失灵保护方案研究

针对基于模块化多电平换流器的柔性直流电网直流侧故障难以快速清除的问题,对基于MMC的柔性直流输电技术的基本原理和3种主流的直流侧故障隔离技术进行了研究。分析比较了3种高压直流断路器技术路线,选择混合式高压直流断路器作为清除柔性直流电网直流侧短路故障的方案,介绍了一种混合式高压直流断路器的基本结构和直流故障处理过程。参考交流电网断路器失灵保护策略,提出基于柔性直流电网的输电线路和母线上直流断路器失灵保护方案,并在PSCAD/EMTDC上搭建模型进行仿真验证。研究结果表明:所提出的断路器失灵保护方案在线路和母线上断路器未成功动作时使相邻断路器跳闸,实现故障的彻底隔离,并清除短路故障电流。     

变电站选用110V直流系统的一些技术措施

本文通过分析220kV及以下变电站采用110V直流系统的情况,指出应提高直流规程规定的直流母线电压允许变化的下限值,以满足断路器合闸操作对直流电压降的要求,并提出应注意选择适当的操作电缆截面.     

An experiment to estimate the revolution of DC motor

In this paper we have reported a simple and cost effective lab level experiment to determine the revolution of DC motor at various voltages.This experiment is designed on the basis of laser light pulses observed in cathode ray oscilloscope(CRO)output through an aperture.These output waveforms are directly related with the revolution of DC motor.A laser light beam was allowed to pass through a slot attached with the shaft of DC motor.The outcoming light is in the form of light pulses that falls on the photodetector which was connected to CRO.The frequency of light pulses is the function of applied voltage to DC motor.The CRO output was measured at different voltages.The visual waveforms on CRO interpret the different values of revolutions per minute(rpm)at different values of voltages given to DC motor.Analysis was made to determine the voltage depended revolution.     

A highly stable DC power supply for precision magnetic field measurements and other purposes

A homogeneous magnetic field is essential for the (3)He neutron spin filter used to polarize neutron beams and analyze neutron spins in neutron scattering. The required spatial uniformity of the magnetic field is on the order of 10(-4)/cm or less. To measure such uniformity, one needs a DC current source with a current stability much better than 10(-4). However, laboratory DC power supplies, which are commonly used in many (3)He neutron spin filters, do not have such stabilities. To attain a highly stable current with a common laboratory DC power supply for every (3)He neutron spin filter, a simple feedback circuit has been developed to keep the output current stable up to 10(-6). Such a highly stable current or voltage from a common laboratory DC power supply can also be used for various other research applications.     

Analysis of transmittance and degree of conversion of composite resins

The objective of this study was to evaluate and correlate light transmittance (T), initial degree of conversion (IDC), and degree of conversion after 24 hr (DC24) for 22 composite resins (CR) for enamel and dentin use. The transmittance (n = 10) was measured with a spectrometer at a wavelength of 468.14 nm. The degree of conversion (DC; n = 5) was measured with Fourier Transform Near‐Infrared Spectroscopy before polymerization, immediately after photoactivation, and 24 hr after photoactivation. Both sets of values are provided as percentages. ANOVA and Games‐Howell (α = 5%) tests showed that Filtek Supreme Ultra gave the highest T values of all enamel CRs, while Esthet‐X HD presented the lowest. Meanwhile, Venus diamond gave the highest values of all dentin CRs, while Esthet‐X HD gave the lowest. For IDC and DC24, ANOVA showed differences between individual CRs and the two CR types (p < .0001). Despite the limitations of this study, it can be concluded that there was no correlation between T and either IDC or DC24 (p > .05); however, IDC and DC24 were strongly correlated (p < .05) by Pearson's correlation. That being said, as a higher DC reflects better mechanical properties, certain conclusions can be drawn about overall performance. The best IDC values were observed for the Opallis enamel resin and the Opallis and Premise dentin resins. Meanwhile, the best DC24 values were observed for the Opallis, Charisma, and Premise enamel resins and the Opallis and Premise dentin resins. Degree of conversion and light transmittance showed differences between composite resin types (enamel and dentin) and brands. It is important to know at the moment of composite choice taking into account mechanical and optical properties.     

Cluster identification in AA5754 aluminium sheets using mathematical morphology analysis

Quantitative image analysis of particle distribution in the microstructure of continuous cast (CC) and direct chill cast (DC) AA5754 aluminium alloy sheets have been conducted. This information can be used as an input for modelling mechanical deformation and instability in these materials. The quantitative analysis reveals that there are significant differences in the microstructure of the two materials even though the total content of second‐phase particles is statistically similar. Qualitative observation shows the second‐phase particles to be arranged in the form of streaks parallel to the rolling direction in the CC sheets and in a uniform random manner in the DC sheets. The main difference in the geometric microstructure of the CC and DC material is the spatial arrangement of the second‐phase particles. A new mathematical technique called proximity analysis is developed to identify clusters and group of particles belonging to a cluster. Quantification through proximity analysis reveals that the particle clusters in CC sheet are in the form of long clusters (streaks) parallel to the rolling direction and are significantly longer than those in DC sheets (with the largest cluster in CC being four times larger than DC), and also have anisotropic angular orientation parallel to the rolling direction. The lower value of fracture strain observed in the CC sheets compared to DC sheets is attributed to a combination of large sizes of clusters and their preferential alignment along the rolling direction in the CC microstructure.     

The noise reduction of a DC motor using multi-body dynamics

The DC motor of a vehicle may cause noise and vibration due to high-speed revolution, which can make a driver feel uncomfortable There have been various studies attempting to solve these problems, mostly focusing on the causes of noise and vibration and a means of preventing them The CAE methodology is more efficient than a real test for the purpose of looking for various design parameters to reduce the noise and vibration of the DC motor In this study, a design process for reducing brush noise is presented with the use of a computer model, which is made by using a multi-body dynamics program (DADS) The design parameters to reduce the brush noise and vibration were proposed using a computer model They were used to reduce the noise and vibration of the DC motor and verified by the test tesults of the fan DC motor in the vehicle This method may be applicable to various DC motors     

直流切趾对光纤光栅特性的影响

从模耦合方程出发,分析了直流切趾对光纤光栅特性的影响,给出了直流切趾和光栅啁啾之间的关系,提出了用线性直流切趾来实现均匀模板制作啁啾光栅和同一啁啾模板制作不同色散特性光栅的方法。实验上,用均匀模板制作了色散量为-2 126 ps/nm的啁啾光栅,并用同一啁啾模板制作出了色散量为-1 599.362 71 ps/nm、-1 250.4 ps/nm和-2 011.4 ps/nm的光栅。实验结果表明,理论和实验符合较好。     

Tribological Behavior of Nickel-Doped Diamond-Like Carbon Thin Films Prepared on Silicon Substrates via Magnetron Sputtering Deposition

In this study, nickel-doped diamond-like carbon (Ni-DLC) thin films were deposited on silicon (Si) substrates using a magnetron cosputtering system by varying DC power density applied to a Ni target at a fixed DC power density applied to a carbon (C) target. Their tribological properties were systematically investigated using a ball-on-disc microtribometer. The tribological results showed that increasing the DC power density applied to the Ni target more than 0.49 W/cm² significantly increased the friction and wear of the Ni-DLC films due to the degraded sp³-bonded cross-linking structures of the films. However, the much lower friction and wear of the Ni-DLC-coated Si samples than those of the uncoated Si sample implied that the Ni-DLC films could effectively prevent their Si substrates from wear. It could be concluded that the Ni-DLC films could be used as high wear-resistant coatings for micromold applications because their tribological properties were significantly influenced by the DC power density applied to the Ni target.