脉冲锁相环的稳定条件

本文论证了一些常见的脉冲锁相环路的稳定条件。并给出了实现环路稳定工作的方法。     

可调叠片式径向剃齿刀的研制

本文概述了径向剃齿刀的特点及其制造中的问题,设计了叠片斜装式径向剃齿刀。应用单自由度啮合原理计算出剃齿刀的理论廓形及与其共轭的砂轮廓形,利用锥面逼近砂轮共轭面,发展了用锥面砂轮刃磨径向剃齿刀的新工艺。     

压气机可调导风装置出口流场的计算与分析

根据压气机喘振和阻塞发生的机理,运用CAD软件建立了压气机进气可调导风装置的几何模型,并对其进行网格划分.用CFD流体计算软件进行三维气动分析,得出可调导风装置出口的速度分布.通过与理想的速度分布相比较,从而调整几何模型和优化计算,获得最佳速度分布.在此基础上,制造出实体并进行了初步的压气机台架实验.结果表明,可调导风装置能够有效地延缓喘振和推迟阻塞的发生,扩大了压气机流量范围.     

一种可实现单相电机对称运行的变频调速方法

根据单相电机对称运行时的合成电压矢量方程 ,提出了考虑单相电动机主、副绕组对称和不对称两种情况下产生圆形旋转磁场的电压矢量式PWM变频调速控制方法 .该方法在保证两相电压分量相位相差90度的条件下 ,使电压分量大小与绕组匝数成正比 ,然后合成为电压矢量 ,产生PWM变频控制信号 .计算机动态仿真结果表明该方法使单相电机产生圆形旋转磁场 ,实现对称运行是有效的 .样机的试验结果证明了用电压矢量式PWM变频控制方法实现单相电机宽范围调速的可行性 .     

离心压缩机进口可调导叶尾缘自诱导吹气数值研究

设计一种可进行尾缘自诱导吹气的可调导叶,减弱动静干涉效果,降低叶轮所受气动载荷,提高叶轮的安全性.该结构通过压差作用,调控导叶尾缘流动现象,补偿导叶的部分尾迹,并以某带有进口可调导叶的离心压缩机为例,采用数值方法予以验证.结果表明,在0°开度下结构内流动不明显.随着开度增加,壁面分离加大,在导叶的面上压差加大,使槽道内部自诱导流动加强.在较低增加叶根尾迹强度的条件下,改善了导叶中部、顶部尾迹分布形式,使纯尾迹减弱为弱尾迹,使叶轮气动载荷降低.同时无外部补气,自诱导结构对机组外特性几乎无影响.     

A mathematical model and numerical solution technique for a novel adjustable hydrodynamic bearing

An analysis model for a novel adjustable hydrodynamic fluid film bearing is described. The principles of hydrodynamic lubrication are outlined together with an expanded version of the governing pressure field equation as related to the novel bearing. Finite difference approximations are given for the pressure field equation and a temperature model, both related to the fluid film thickness. Relationships of viscosity with temperature and pressure are included. A finite element model and an iterative computational process are described, whereby full simultaneously converged field solutions for fluid film thickness, temperature, viscosity and pressure were obtained, together with oil film forces. The model and solution process were developed to apply to a variety of hydrodynamic bearings and an outline is given of its extensive use in the design and simulation of one version of the novel bearing. Observations are given on the operation, success rates and verifications of the computational process. Copyright © 1999 John Wiley & Sons, Ltd.     

鉴频中周失谐对鉴频特性的影响

分析了集成峰值鉴频器的工作原理,得出鉴频中周失谐的原因是内置的配谐瓷管电容容量的衰减。衰减机理是该电容内外表面的银涂覆层受空气中硫化氢的侵蚀,局部或大面积生成硫化银而变黑,电极的有效面积减小,导致电容量减小。改进配谐瓷管电容生产工艺,在内外层圆柱型银的表面加保护层可有效防止中周失谐。     

无约束非线性l_p问题的调节熵方法

本文构造了求解无约束非线性lp问题的新方法——调节熵函数法。给出了数值算法,证明了算法的收敛性。通过数值仿真将该方法与求解无约束非线性lp问题的极大熵函数法进行了比较,表明该算法是十分有效的。     

Optical design of adjustable light emitting diode for different lighting requirements

<正>Light emitting diode(LED) sources have been widely used for illumination.Optical design,especially freedom compact lens design is necessary to make LED sources applied in lighting industry,such as large-range interior lighting and small-range condensed lighting.For different lighting requirements,the size of target planes should be variable.In our paper we provide a method to design freedom lens according to the energy conservation law and Snell law through establishing energy mapping between the luminous flux emitted by a Lambertian LED source and a certain area of the target plane.The algorithm of our design can easily change the radius of each circular target plane,which makes the size of the target plane adjustable.Ray-tracing software Tracepro is used to validate the illuminance maps and polar-distribution maps.We design lenses for different sizes of target planes to meet specific lighting requirements.     

能量连续可调LCS光源SINAP-III

X/γ探测器在航天等国家战略需求领域具有非常广泛和重要的应用。 然而, X/γ探测器要在其有效能区进行精确的标定后才能发挥作用。 目前我国缺乏sub MeV～MeV能量连续可调、 单色性好的γ源, 而用于航天的X/γ探测器无法完成精确定标, 从而使航天探测的发展出现瓶颈问题。 提出了升级原有的激光康普顿散射(LCS)原理性实验装置的方案, 建立了一个通过改变激光入射角来连续调节散射光子能量、 准单色、 极化、 sub MeV～MeV LCS光源(SINAP-III), 从而开拓LCS光源在我国航天领域（如用于航天的X/γ探测器能量定标和抗辐射加固评估研究）的崭新应用前景, 并为将来建设一个基础和应用研究相结合的多功能的γ源实验平台打下基础。 The X/γ detectors in the field of national stratagem, such as astronautical technology, have very broad and important application. These detectors, however, will play their role properly only after accurate calibrations in effective energy region. For the shortage of continuously adjustable and quasi monochromatic γ source in China, it is impossible for the detector employed in aerospace to achieve an accurate calibration so that development of such detector has encountered a big obstacle (or a bottleneck). Therefore, we propose to upgrade the original LCS device to an adjustable photon energy by changing incident angle of laser beam, monochromatic, and polarized sub MeV~MeV LCS γ source(SIMAP III) , in order to explore the new applications of LCS γ source in aerospace as well as to establish a platform for a multifunctional of γ source.