钕铁硼永磁电机在汽车上的应用前景广阔

电机是汽车中不可缺少的部件,气车上电机数量在逐年增加。一般汽车上有8—18台,高级轿车多达40～50台,随着汽车工业的发展,汽车电机的需求是巨大的。 钕铁硼水磁材料性能优异,用于制造电机具有体积小、量轻、效率高和节能的优点。美国已将14种汽车改用钕铁硼永磁电机,并要实现汽车电机“钕铁硼化”。汽车工业的发展,将对推(?)应用稀土永磁材料产生重要影响。 汽车工业是我国支柱产业之一,

新型多关节式机械手臂的机构设计

在机械手的动力传输和关节结构方面提出了新的构想 。

Sensitivity and effect of key operational parameters on performance of a dual-cylinder free-piston engine generator

The free-piston engine generator(FPEG)is regarded as the next generation of energy conversion system which may replace traditional engines in the future.The effect of key operational parameters like excess air ratio of input mixture and ignition position on the engine performance of a dual-cylinder FPEG was investigated,and their sensitivity was analyzed in this paper.The operating compression ratio of the system is susceptible to changes in excess air ratio and ignition position.At the same time,it decreases from 15.8 to 6.6 when excess air ratio increases from 0.85 to 1.15,but it increases from 6.1 to 13.3 as ignition position increases from 15 mm to 20 mm.The operating frequency and indicated power are more sensitive to changes in excess air ratio than ignition position.But it is the opposite for the indicated thermal efficiency and friction loss.Excess air ratio and ignition position have a quite similar influence on heat transfer.Therefore,from the perspective of system operation and performance,it is preferable to keep excess air coefficient slightly below 1.0.In contrast,when selecting ignition position,it is of great importance to comprehensively consider the risk of structural damage caused by the increase in the compression ratio and in-cylinder gas pressure.

浅谈船舶交流电站的选定

以黑龙江水系船舶电站为例,介绍了船舶电站选定的方法和计算步骤。

Effects of Yb addition on microstructures and mechanical properties of 2519A aluminum alloy plate

The effects of Yb content on the microstructures and mechanical properties of 2519A aluminum alloy plate were investigated by means of tensile test,optical microscopy,transmission electron microscopy,scanning electron microscopy and X-ray diffractometer.The results show that addition of 0.17% (mass fraction) Yb increases the density of θ' particles of the 2519A alloy plate and reduces the coarsening speed rate of θ' phase at 300 ℃.Therefore,tensile strength is enhanced from 483.2 MPa to 501.0 MPa at room temperature and is improved from 139.5 MPa to 169.4 MPa at 300 ℃.The results also show that with the addition of 0.30% (mass fraction) Yb,the mechanical properties increase at 300 ℃ and decrease at room temperature.With Yb additions,the Al7.4Cu9.6Yb2 phase is found whilst the segregated phases of as-cast alloys along grain boundaries become discontinuous,thin and spheroidized.

A novel current vector decomposition controller design for six-phase permanent magnet synchronous motor

The vector control algorithm based on vector space decomposition （VSD） transformation method has a more flexible control freedom, which can control the fundamental and harmonic subspace separately. To this end, a current vector decoupling control algorithm for six-phase permanent magnet synchronous motor （PMSM） is designed. Using the proposed synchronous rotating coordinate transformation matrix, the fundamental and harmonic components in d-q subspace are changed into direct current （DC） component, only using the traditional proportional integral （PI） controller can meet the non-static difference adjustment, and the controller parameter design method is given by employing intemal model principle. In addition, in order to remove the 5th and 7th harmonic components of stator current, the current PI controller parallel with resonant controller is employed in x-y subspace to realize the specific harmonic component compensation. Simulation results verify the effectiveness of current decoupling vector controller.

MATERIAL ELECTROMAGNETIC PARAMETERS EXTRACTION USING SVM METHOD

The method extracting the electromagnetic parameters from scattering coefficients was studied in this paper. The Support Vector Machine (SVM) method is used to solve the inverse problem of parameters extraction. The mapping relationship is set up by calculating a large number of S pa-rameters from the samples with different permittivity by using transmission line theory. The simulated data set is used as training data set for SVM. After the training, the SVM is used to predict the permittivity of material from the scattering coefficients.

Experimental investigation of effect of refrigerant gases,compressor lubricant and operating conditions on performance of a heat pump

In the field of heat pumps,there are a number of parameters that affect the performance and efficiency of the apparatus,which have been the subject of studies by individual researchers in the literature.This study describes an experimental method in order to investigate the effects of some significant parameters on heat pump performance.In this regard,a laboratory heat pump setup has been utilized to operate in different working conditions for achieving an appropriate estimation to find out effects of mentioned parameters such as refrigerant type and charge amount,compressor oil viscosity,compressor cooling fan,secondary fluids temperature and flow rate.Different refrigerants have been selected and used as circulating fluid in the installed heat pump.Although this work has been devoted to a detailed attempt to recognize the effects of various parameters on the coefficient of performance(COP) value,an appropriate method has been carried out to survey the obtained results by using economic analysis.It was revealed that one of the main parameters is refrigerant charge amount which has a notable effect on COP.The temperature of the heat source was also tested and the performance of the system increased by more than 11% by employing mentioned modifications and various operating conditions.In addition,by selecting a low viscosity compressor oil,the system performance increased by 18%.This improvement is more than 6% for the case that cooling fan is installed to cool the compressor element.

Fabrication of solenoid-type microinductor with different magnetic core schemes by MEMS technique

Two micromachined solenoid-type inductors with different electroplated core structures, ellipse and rectangle, were fabricated, tested and compared in order to reach optimum designs for integrated induetoes and transformers. In the process of fabrication, UV-LIGA, dry. etching technique, fine polishing and eleetroplating techniques have been adopted to achieve high performance mieminduetor. Experimental results show that both types of the induetors are characterized by high inductance, Q-factor and low electrical resistance. While the inductance of the inductor with rectangular magnetic core is slightly higher than that with elliptical magnetic core, the quality factor of the latter is larger than that of the former.

Monte-Carlo Simulation of Multiple-Molecular-Motor Transport

Multimotor transport is studied by Monte-Carlo simulation with consideration of motor detachment fromthe filament.Our work shows, in the case of low load, the velocity of multi-motor system can decrease or increase withincreasing motor numbers depending on the single motor force-velocity curve.The stall force and run-length reducedgreatly compared to other models.Especially in the case of low ATP concentrations, the stall force of multi motortransport even smaller than the single motor's stall force.

P300 EEG Recognition Based on SVM Approach

In this paper, we used SVM method to detect P300 signal. Before training a classification parameter for the SVM, several preprocessing operations were applied to the data including filtering, downsampling, single trial extraction, windsorizing, electrode selection et al. With the SVM algorithm, the classification accuracy could be up to above 80%. In some cases, the accuracy could reach 100%. It is suitable to use SVM for P300 EEG recognition in the P300-based brain-computer interface (BCI) system. Our further work will include the improvement to yield higher classification accuracy using fewer trials.

Study on Negative Impact of Harmonic Components on Sensitive Electric Equipment

Distribution systems operators are often confronted with declined power quality, which can cause substantial economical losses. The problem analyzed in paper concerns thyristor controlled direct current motor used for ski-lift in ski resort as a source of disturbances with negative impact on sensitive electric equipment, which is then unable to operate correctly. To solve mentioned problems, series of measurements of voltage quality parameters were carried out according to the respective valid standards. Crucial power quality parameters necessary for parallel power active filter design were then analyzed. Power active filter compensates power factor and filters characteristic current harmonics. After power active filter was put into operation, power quality problems were eliminated. Payback period is estimated up to four years.

吸油烟机选用时安全性能莫忽视——从国家监督抽查结果吸油烟机产品质量

目前市场上的吸油烟机按产品结构可分为薄型、半深型和深型三种;按控制方式的不同可分为机械开关控制型和电子开关控制型两种;按电机数量分有单电机和双电机两种。据初步统计,全国现有吸油烟机生产企业共有250多家,主要集中在广东、浙江、江苏等地,本次抽查了广东、浙江、江苏、

A novel integrated quantum circuit for high-order W-state generation and its highly precise characterization

Multipartite entangled states like the W-class are of growing interest since they exhibit a variety of possible applications ranging from quantum computation to genuine random number generation. Here, we present a universal setup to generate high-order single photon W-states based on three-dimensional integrated-photonic waveguide struc- tures. Additionally, we present a novel method to charac- terize the device＇s unitary by means of classical light only.