Trace structure analysis,ptychography, phase tomography

Three papers dedicated to the author elicit further comment stemming from his own engagement with the three topics- trace structure analysis, ptychography and phase tomography.     

Effect of Impeller Geometry,Rotational Speed,and Fluid Properties on Seal Chamber Flow

Particle Image Velocimetry (PIV) and Laser Doppler Velocimetry (LDV) are used to measure the three components of the flow velocity in the seal chamber of a mechanical pusher seal at three shaft rotational speeds of 1000, 1800, and 3600 rpm. The flow details in the narrow gap region between the rotor and the stator are also measured. The Taylor numbers corresponding to the three rotational speeds with water and a lightweight heat transfer mineral oil used as process fluids varied between 1.087 × 10⁷ and 9.48 × 10¹⁰. A smaller size impeller with diameter 12.7 cm compared with 25.4 cm diameter impeller used in previous works, was used in this research. Large differences are observed between flow structures in the seal chamber flow for oil and water. The effect of impeller size and the location of balance holes on the seal chamber flow for water at rotational speed of 1800 rpm is presented     

用活CAD软件,学好机械制图

通过分析目前制图课程的现状,作者提出了改进措施,将"机械制图、电子图版、三维实体造型"三门课程进行整合,构建出新的课程体系。通过教学实践证明,新课程体系增强了学生的学习兴趣,提高了学习的主动性,教学效果有明显改善。     

Shielding of longitudinal magnetic fields with thin, closely spaced, concentric cylinders of high permeability material

Formulae for the longitudinal shielding effectiveness of N thin, closely spaced, concentric cylinders of high permeability material have been developed and experimentally tested. For shields which cannot be oriented, or which change their orientation in the ambient field, the shielding effectiveness for longitudinal fields is generally the limiting criterion and no design formulae have previously been published for more than two shields. A simple diagrammatical method of writing the shielding formula is presented. Use of these equations is demonstrated by application to the design of magnetic shields for hydrogen maser atomic clocks. Examples of design tradeoffs such as size, weight, and material thickness are discussed. Experimental data on three sets of shields fabricated by three manufacturers are presented.     

Localization of metals in cells of saprophagous soil arthropods (Isopoda, Diplopoda, Collembola)

This review summarizes results on the intracellular distribution of metals in cells of woodlice (Isopoda), millipedes (Diplopoda), and springtails (Collembola), which are three major groups of saprophagous arthropods contributing to the turnover of soil organic matter. Although the impact of metals and also metal pollution has inevitably been shown at levels of higher biological organization than subcellular mechanisms in these animal groups, the aim of this review is to focus exclusively on storage sites and aspects of intracellular metal metabolism. Thus, methodologically, results obtained by microscopical techniques such as histochemistry, X-ray microanalysis, energy filter transmission electron microscopy, or laser microprobe mass spectrometry were given preference. Results from atomic absorption spectrophotometry of cellular fractions were kept to a minimum. In all three taxa, the main intracellular metal storage sites are various types of "granules" which are widely distributed throughout cell types associated with the digestive system.     

Validation of a method using Taguchi,response surface,neural network,and genetic algorithm

Piston is one of the important parts for aircraft engine, and the quality of piston affects the efficiency and safety of the engine. This study applies Taguchi method, response surface methodology (RSM), and back-propagation neural networks (BPNN) combining with genetic algorithm (GA) on the quality improvement of piston manufacturing processes to enhance the process yield. The Taguchi parameter design concerns three nominal-the-best specifications, including ring groove diameter specification, inner groove diameter specification, and inner diameter of pistons. Together with five control factors consisting of (1) type of carbon steel, (2) type of cutting fluid, (3) cutting depth, (4) spindle speed, and (5) chuck pressure, the L₂₇(3¹³) orthogonal array was selected for this experiment. Three models: (1) Taguchi model, (2) Taguchi_RSM model, and (3) Taguchi_BPNN_GA model were constructed to find the parameter combinations of five control factors for each model. Confirmation experiments were done for each model and the performances of three models were also compared to indict the enhancement of manufacturing quality of piston.     

油水气三相计量的新方法

油井三相流的分离分相计量精度主要是受气液分离程度和含水率计的精度的影响。文中提出利用涡街流量计和涡轮流量计的响应函数来控制气液分离，其控制算法是基于BP网络改进的PID控制算法。含水率测量选用高精度的同轴线相位法含水率计，满足了油井三相流的精确计量要求。     

ICP-AES法测定碳钢、低合金钢中13种元素

本文选择了硝酸、王水、逆王水,进行碳钢、低合金钢溶样条件试验,以谱线强度为指标,溶解酸种类、溶解酸浓度、溶解酸用量、定容酸用量等四因素为变化条件,各因素中有三水平,即按正交实验表L_9(3~4)进行试验,编制计算程序,快速、科学地优选出最佳溶样条件—30ml NHO_3(1+5v/v)和3ml HCl,ICP-AES法同时测定铝、砷、铬、钴、铜、磷、锰、钼、镍、硅、锡、钛和钒13种元素。为确定测试方法的重复性(r)和再现性(R)而进行精密度试验。精密度数据是由10个实验室对7个样品作试验确定的。方法的回收率为94％-105％。精密度在8％以内。     

Theoretical, numerical and experimental study on synchronization of three identical exciters in a vibrating system

The theory on synchronization of two exciters is more widely used in engineering, while that of more than two exciters is less considered. So it is of great significant to investigate synchronization of three exciters. Firstly by introducing the average method of modified small parameters, the dimensionless coupling equations(DCE) of three exciters are derived, which convert the problem of synchronization into that of existence and stability of zero solutions for the DCE and lead to the construction on criterions of synchronization and stability in the simplified form for three exciters. Then the synchronization criterion is discussed numerically, as well as the abilities of synchronization and stability, some results thereof indicate that the synchronization ability increases with the increase of the coupling moment among three exciters, but decreases with that of their phase differences. Finally, an experiment on synchronization with three exciters is carried out. Through the comparison and analysis of experimental data on phase differences among three exciters, responses of system, and phases of three exciters recorded by high-speed camera, the parameters of system satisfying the above two criterions can ensure the synchronous and stable operation of three exciters. As a result, the average method of modified small parameters can be used as a theoretical apparatus studying reasonably the synchronization mechanism of three exciters, it is also proved to be useful and feasible by numeric and experiment. The present research lays the foundation and guidance for the establishment of synchronization theory system with multi-exciter and engineering design.     

生产过程时间、成本与质量综合优化研究

时间、成本与质量是制造企业追求的3大目标,它们相互制约、相互影响,分析三者作用关系和实现综合优化是制造过程非常值得研究的重要难题。根据大量实践调研和总结,剖析了成本、时间和质量的内在相互作用机理,确立了三者之间的影响规律和相互关系。基于关系图,建立了时间-成本-质量综合优化模型。采用精确计算思想设计专门程序对模型进行优化求解。针对一个汽车零件生产实例,详细阐述了所提方法的应用过程,得到一系列优化结果,通过分析求解结果,总结出对企业管理人员非常有价值的结论。实例验算表明,提出的方法可以有效辅助生产决策。     

三环减速器齿廓间隙角啮合刚度和载荷分配的计算

在考虑内啮合齿轮副齿廓间隙角的基础上，建立起三环减速器各啮合轮齿上栽荷分配的理论分析模型。使用SHQ40实例计算出在额定载荷工况下作用在各啮合轮齿对上的栽荷，计算结果表明多轮齿同时啮合可提高三环减速器的承栽能力。     

Application,synthesis, and manufacture of involute gear transmissions with asymmetric gear profiles

By investigating possible applications of involute gear transmissions with asymmetric gear profiles, three levels of transmissions may be identified. Each level is characterized by a particular set of engagement angles, operational parameters, types of gear, and manufacturing methods. This classification permits easy identification of their properties and facilitates the design of such transmissions.     

Tribological Properties of Graphite-Fiber-Reinforced,Partially Fluorinated Polyimide Composites

Graphite-fiber-reinforced polyimide (GFRPI) composites were formulated form three new partially fluorinated polyimides and three types of graphite fiber. Nine composites were molded into pins and evaluated in a pin-on-disk tribometer. Friction coefficients, wear rates, pin wear surface morphology, and transfer film formation were assessed at 25 and 300°C. Also assessed was the effect of sliding distance on friction and the effect of constantly increasing or decreasing temperature on friction. Wear was up to two orders of magnitude lower at 25°C and up to one order of magnitude lower at 300°C than with previously formulated NASA GFRPI composites.     

技术创新的意义、内涵和环境

首先讨论了技术创新的意义 ,将技术创新分为产品创新、过程创新和管理创新三个部分 ,并对这三部分的关系进行了探讨。还对技术创新的环境进行了研究 ,如有利于技术创新的组织和管理环境、透明和畅通的信息流、简化的产品信息等     

同步器摩擦特性建模仿真与试验

同步器在同步过程中经历了液力摩擦、混合摩擦、固体摩擦三个阶段。为了有效地分析同步器的工作过程,分别对三个阶段建立了数学模型。利用AMESim和MATLAB-Simulink模块建立了同步器工作过程的联合仿真模型,并进行了仿真分析与试验验证。研究结果表明：仿真模型能够对换挡力、换挡位移、同步力矩、变速器输入转速进行准确地仿真,对同步时间的计算误差小于9.58%。     

Met-Pro Corp,USA

Met-Pro’s first quarter sales, at US$17.0 million, were up 5% on last year’s US$16.2 million, while net income for the three months ended 30 April 2003 increased 12% to US$1.4 million.     

浅析机械企业实施质量、环境及职业健康安全管理体系的方法

结合机械企业的现状和发展,分析了机械企业实施质量、环境、职业健康安全管理体系应采取的的方法,只有实现三体系的一体化,并坚持持续改进的原则,一定会对企业的发展产生强大的推动力.     

利用物质磁化性质定性分析邻间对苯二酚同分异构体

研究了一项新的分析技术"电磁感应式磁化定性分析装置".采用该技术定性分析了邻、间、对苯二酚同分异构体样品,监测了3种苯二酚溶液在一段时间内的氧化过程.该分析技术是利用不同单组分样品的磁化性质不同的原理,采用检测电磁感应电动势的方法、测定样品磁化后所产生的附加磁场变量强度进行定性分析的,通过实验表明,该分析技术可以定性分析邻、间、对苯二酚同分异构和大分子量样品,还可以监测样品的动态氧化还原过程.     

Study of the spinal cords of the sturgeon Acipenser schrenckii, gar Lepisosteus oculatus, and goldfish Carassius auratus by morphological, immunohistochemical, and biochemical approaches

Little is known about the spinal cords of phylogenetically ancient actinopterygeans. The spinal cords of the chondrostean Acipenser schrenckii (Amur sturgeon), holostean Lepisosteus oculatus (spotted gar), and teleost Carassius auratus (goldfish) were, therefore, analyzed by immunohistochemistry, electron microscopy and two-dimensional gel electrophoresis. Morphology showed numerous similarities between sturgeons and gars. In both, a dorsal column between the two dorsal horns was lacking, giving the grey matter an inverted Y-shape. In goldfish, a small dorsal column was seen, the grey matter occupied a larger area, neuronal density was much higher, and a ventral commissure was apparent, which was absent in sturgeons and gars. In the white matter of sturgeons and gars, small caliber axons predominated, whereas larger axons were frequent in goldfish. Choline acetyltransferase immunoreactive neurons were prevalent in the ventral horns of all three fish, mainly in motoneurons, but stained fibers were only found in sturgeons and gars. gamma-aminobutyric acid positive cells were seen in both the ventral and the dorsal horns of all three fish. Distribution of serotonin (5-HT) and tyrosine hydroxylase (TH) immunoreaction was similar in sturgeons and gars, being located in both the ventral and the dorsal horns. In goldfish, 5-HT label was confined to the ventral horn and TH label was mainly observed in a cell group located ventromedially. Two-dimensional gel electrophoresis showed a gradual increase in protein number from sturgeons to gars to goldfish. In conclusion, the spinal cords of sturgeons and gars share many morphological and chemical features, distinguishing them from the goldfish spinal cord.     

DETERMINATION OF COPPER,IRON, LEAD,MAGNESIUM, MANGANESE,AND POTASSIUM IN RICE FROM INDIA AND UNITED STATES BY INDUCTIVELY COUPLED PLASMA-OPTICAL EMISSION SPECTROMETRY

Rice from several regions in India and two areas of the U.S. were determined for selected metals following sample preparation using microwave technology for subsequent determination by inductively coupled plasma-optical emission spectrometry. Lead was not detectable in four of the rice samples and sub-part per million (ppm) for the remaining three rice samples. Concentrations of copper and manganese were in the ppm range, iron in the tens of ppm, and magnesium and potassium in hundreds to thousands of ppm.