采用多级变速法生长AlGaAs电流扩展层的850nm红外发光二极管

对采用多级变速法生长AlGaAs电流扩展层的850nm红外发光二极管进行了研究。研究发现,采用多级变速法生长n型Al0.25Ga0.75As电流扩展层有助于改善外延层表面形貌和后续外延层的晶体质量,从而减小850nm红外发光二极管的漏电流及串联电阻。此外,采用多级变速法生长n型Al0.25Ga0.75As电流扩展层还可以避免在多量子阱(MQW)有源区中形成非辐射复合中心,从而提高850nm红外发光二极管的亮度和寿命。

变速法铣削花键轴阶台

在齿轮变速传动中,花键轴是必需的零件之一。滑移齿轮在花键轴上滑动与不同的齿轮啮合,达到变速的目的。我校实习厂长期为某拖拉机厂生产变速箱花键轴类零件,由于生产批量大,均采用展成法在花键轴铣床上加工。

变速升流过滤中和法处理钢厂酸洗废水

针对某钢厂年产 1 4万t无缝钢管新建项目产生酸洗废酸液、酸性废水的水质水量特征 ,采用变速升流式过滤中和法对酸洗废水进行中和处理。在设计进水量为 1 0 0 0m3/d ,H2 SO4 1 5 90t/a ,FeSO4 5 6 6 3t/a时 ,处理后水质稳定 ,达到国家《钢铁工业水污染物排放标准》(GB1 345 6 - 92 )二级标准。重点分析了该废水处理工程的设计特点、运行效果和成本估算。

变速液面恢复法在特殊流程油井计量中的应用

随着地面工艺流程优化、简化程度的提升,集油流程出现多样化,环井、串联井井数不断增加,对于此类油井的产量计量,目前常用的计量方法已不能适应油田开发需要。利用高等数学理论研制出的变速液面恢复法,可解决此类油井产量计量问题。经多个采油厂的现场试验表明:变速液面恢复法用于环井、串联井计量,平均计量相对误差在±10%以内,适用范围较广。该项研究成果为特殊流程油井提供了一种计量精度高、停产时间短的计量手段,对地面工艺的优化、简化起到了积极的促进作用,具有良好的推广应用前景。

江苏地区中、古生界构造成图方法研究及其应用效果

杨德洲 ,金兴国 ,宣小石 ,华伟 ,樊幼华 ,吴义杰 .江苏地区中、古生界构造成图方法研究及其应用效果 .石油地球物理勘探 ,2 0 0 1,36 (5 ) :6 18～ 6 2 5 在速度随深度呈线性或准线性变化的地区 ,主要有两种常规构造成图方法 :1对由水平叠加解释剖面得到的等 t0 图进行空校 ;2对由偏移解释剖面得到的等 t0 图采用统一速度进行时—深转换。针对江苏地区中、古生界地层速度“在纵向上随深度呈非线性变化 ,且横向变化大”的特点 ,本文提出了分区剥皮成图方法系列 ,即 :一般剥皮法、分层等效变速法、等效分步成图法。这些方法很好地消除了常规成图方法在以碳酸盐岩储层为主要目的层地区的不适应性 ,具有简便易行、精度高的特点 。

变速变桨距风电机组减载调频综合控制策略研究

为了适应高风电渗透电力系统调频需求,各国风电并网导则均要求风电场具有参与系统调频的能力.由于双馈感应风电机组调频能力与其运行工况相关,不计工况统一减载调度必然存在不合理性.围绕DFIG调频控制策略,提出一种变速与变桨协调控制减载运行控制策略,整定具备功率向上调节能力的减载运行曲线,基于仿真计算得到各风速下风电机组最大可下调功率范围,并通过下垂频率调整控制,检验减载运行方式下风电机组对系统频率的支持作用.仿真研究表明:考虑各风电机组调频能力差异来优化配置各风电机组的调频容量,可以提高调频调度的合理性.

关于资产折旧的创新性研究

根据胡锦涛同志在十八大报告中提出的要更多依靠"管理创新驱动"经济发展的要求,本文系统分析了传统折旧方法的优缺点,针对生态工程、民生工程和融资租赁等不同领域管理实务的需求,明确提出固定资产减速折旧方法,以期科学地计提折旧费用,加强经济管理,实现企业永续发展。

梯形螺纹车削程序的编制初探

本文针对梯形螺纹数控车削加工过程中易扎刀、精度低等问题,采用左右切削法、分层切削法、主轴变速等方法实现梯形螺纹精度的控制。

OPTIMAL DESIGN OF DUAL STATOR-WINDING INDUCTION GENERATOR WITH PWM CONVERTER

To minimize the reactive power of the converter of the control winding in the novel dual stator-winding induction generator based on the PWM converter, design features of the induction generator with a rectified load are proposed. The optimization method of excited capacitors to minimize the reactive power of the control winding at a variable speed is given. The calculation capacity of the machine with a diode bridge rectifier load is proposed. To achieve global searching, the integrated method with the improved real-coded genetic algorithm and the twodimensional finite element method （FEM） is introduced. Design results of the sample show that reactive power can be reduced by the method, and the converter capacity can be decreased to 1/3 of output rated power at the speed ratio of 1 ： 3, thus reducing the volume and the mass of the inverter.

Improving IAC Algorithm Based on Range Rate Measurement

Aim Interactive multiple model(IMM) algorithm was introduced into two? stage estimation to improve the estimating accuracy for system position and velocity.Methods The state estimation was carried out in mixed coordinates according to the nonlinear measure equation, a generalized interactive acceleration compensation(IAC) algorithm in mixed coordinate was presented. Results Simulation result shows the estimation accuracy is improved through changing measure equation in polar coordinates. Conclusion The estimation accuracy for position and velocity estimation, has been improved greatly, and the proposed algorithm has the advantage of less calculating time comparing with other multiple model methods.

SCC evaluation of ultra-high strength steel in acidic chloride solution

The stress corrosion crack （SCC） susceptibility of ultra-high strength steel AerMet 100 was investigated by slow strain rate technique （SSRT）, tensile with polarization and surface analysis technique. The curves of tf^Cl/tf^W -strain rate are divided into three regions： stress-dominated region, SCC-dominated region, and corrosion-dominated region, so as the curves of εf^Cl/εf^W - strain rate and tm/tf-strain rate. The results of tensile tests with polarization show that the main SCC mechanism of AerMet 100 is anodic dissolution, which controls the corrosion process. The three regions have been discussed according to the relationship between the rate of slip-step formation and the rate of dissolution. Fracture appearances in different environments were analyzed by scanning electron microscopy （SEM）. SCC fracture appears as a mixture of intergranular and dimples, while it is totally dimples in the inert environment. The εf becomes the parameter to predict tf because the relationship between εf^Cl/εf^W and tf^Cl/tf^w is a straight line for AerMet 100.

P-FFT and FG-FFT with real coefficients algorithm for the EFIE

In order to reduce the storage amount for the sparse coefficient matrix in pre-corrected fast Fourier transform （P-FFT） or fitting the Green function fast Fourier transform （FG-FFT）, the real coefficients are solved by improving the solution method of the coefficient equations. The novel method in both P-FFT and FG-FFT for the electric field integral equation （EFIE） is employed. With the proposed method, the storage amount for the sparse coefficient matrix can be reduced to the same level as that in the adaptive integral method （AIM） or the integral equation fast Fourier transform （IE-FFT）. Meanwhile, the new algorithms do not increase the number of the FFTs used in a matrix-vector product, and maintain almost the same level of accuracy as the original versions. Besides, in respect of the time cost in each iteration, the new algorithms have also the same level as AIM （or IE- FFF）. The numerical examples demonstrate the advantages of the proposed method.

Effect of a novel three-step aging on strength, stress corrosion cracking and microstructure of AA7085

The influence of a novel three-step aging on strength, stress corrosion cracking(SCC) and microstructure of AA7085 was investigated by tensile testing and slow strain rate testing combined with transmission electron microscopy(TEM). The results indicate that with the increase of second-step aging time of two-step aging, the mechanical properties increase first and then decrease, while the SCC resistance increases. Compared with two-step aging, three-step aging treatment improves SCC resistance and the strength increases by about 5%. The effects of novel three-step aging on strength and SCC resistance are explained by the role of matrix precipitates and grain boundary precipitates, respectively.

Modeling Strain Rate Effect for Heterogeneous Brittle Materials

Rocks are heterogeneous from the point of dynamic failure behavior. Both the compressive and microstructure which is of significance to their tensile strength of rock-like materials is regarded different from the static strength. The present study adopts smoothed particle hydrodynamics （SPH） which is a virtual particle based meshfree method to investigate strain rate effect for heterogeneous brittle materials. The SPH method is capable of simulating rock fracture, free of the mesh constraint of the traditional FEM and FDM models. A pressure dependent J-H constitutive model involving heterogeneity is employed in the numerical modeling. The results show the compressive strength increases with the increase of strain rate as well as the tensile strength, which is important to the engineering design.

The SVD of the EMG basis on the FFT of the Kaiser window

The EMG signal is a present field of research which is a driving force in sources of rehabilitating robots. The FFT with Kaiser Window was used in this paper to analyze the spectral characteristics of the EMG signal according to the characteristic of time changing and nonlinearity for the EMG signal and good results have been obtained. The singular value expressing the property of every EMG signal at each channel was taken out. It offered important data for the actual control of rehabilitating robots.

Application of clutch to clutch gear shift technology for a new automatic transmission

For the purpose of engineering development for a new 8-step speed automatic transmission,a simplified dynamic model for this gearbox was established and key parameters which affected the shift quality were analyzed.Aiming at four different shift types,the ideal characteristics of shift clutch and engine control were set up.By using torque estimation method,PI slip control algorithm and engine coordinated control principle,the control model and transmission controller were well developed for three shift phases which included rapid-fill phase,torque phase and inertia phase.The testing environment on the rig and prototype vehicle level was built and the testing results obtained in ultimate condition could verify the accuracy and feasibility of this shift control strategy.The peak jerk during shift process was controlled within ±2 g/s where the smooth gearshift was obtained.The development proposal and algorithm have a high value for engineering application.

Solution of rectangular bar forging with bulging of sides by strain rate vector inner-product

Abstract：ools. The effective strain rate for for determining the total pressure developed during forging of a rectangular bar forging with bulging was expressed in terms of four-dimensional strain rate vector. The inner-product of the vector was termwise integrated and summed. The integral mean value theorem was applied to determining the ratio of the strain rate components and the values of direction cosine of the vector and then an analytical solution of stress effective factor was obtained. The compression experiments of pure lead bar were performed to test the accuracy of the solution. The optimized results of total pressure by golden section search were compared with those of the indicator readings of the testing machine. It indicates that the optimized total pressures are 2.60%-10.14% higher than those measured. The solution is available and still an upper-bound solution.

Design of a continuously variable Mach-number nozzle

A design method was developed to specify the profile of the continuously variable Mach-number nozzle for the supersonic wind tunnel. The controllable contour design technique was applied to obtaining the original nozzle profile, while other Machnumbers were derived from the transformation of the original profile. A design scheme, covering a Mach-number range of3.0<Ma<4.0, was shown to illustrate the present design technique. To fully validate the present design method, computational fluid dynamics(CFD) analyses were carried out to study the flow quality in the test area of the nozzle. The computed results indicate that exit uniform flow is obtained with 1.19% of the maximal Mach-number deviation at the nozzle exit. The present design method achieves the continuously variable Mach-number flow during a wind tunnel running.