基于模糊层次分析法的刀具供应商的选择

为了对刀具供应商进行最优选择,建立了最优刀具供应商评价指标体系.采用层次分析法建立评价指标的权重值,应用模糊综合评价法进行综合评价.为便于对各个供应商进行比较,对评价结果进行了量化.运用该数学模型,对某机加工厂的刀具供应商进行排序,排序结果符合实际,同时验证了模型的可靠性.     

砌块成型机振动模态与谐响应分析及设计改进

对某砌块成型机进行了有限元建模,介绍了建模方法,通过砌块成型机的模态试验结果,对其进行了修正.分析了各阶模态振型.修正结果表明,砌块成型机模型能够反映其真实的动态特性,同时对振动台进行了谐响应分析,得出了砌块成型机振动台的理论振幅值,并对砌块质量进行了评价.最后根据现场测试对砌块成型机进行了结构改进.     

自导向径向转向架导向梁刚度有限元分析及结构优化

利用有限元软件ANSYS,对自导向径向转向架导向梁的刚度进行分析.并在上述基础上,对导向梁进行优化.并且根据优化结果,对导向梁的结构进行改进,同时对改进后的导向梁刚度进行分析比较.     

圆形料场取料行走机构设计分析

圆形料场堆取料机是一种环保的大型机械设备,取料行走机构的性能直接影响取料机和整机设备的稳定运行.对取料行走机构进行结构设计,对台车架进行有限元分析,结合分析结果对其结构提出改进措施.对车轮组进行分析,主要包括车轮和车轮轴.对车轮进行分析,给出其设计计算式,并对车轮轴进行分析.整个分析过程可以为圆形料场取料行走机构设计提供有效参考,也为其他工程机械的行走机构的设计及其分析提供重要的设计依据.     

高强度螺栓预拉力与滑移系数实验研究

本文报道了对高强度螺栓连接副进行预拉力实验与对高强度螺栓连接母材进行抗滑移实验的结果.得出了高强度螺栓的预拉力、扭矩系数、抗滑移系数等.对实验结果进行分析讨论.     

轮式移动机器人的运动及定位分析

对机器人的结构组成和功能进行了介绍,这是对机器人进行路径规划的基础.而具体的规划策略首先取决于机器人的运动机构,故对其进行运动分析.还对机器人的方位确定问题进行了论述,在电机码盘作为传感器的条件下,对机器人的方位确定进行了具体的推导.这些都是为以后机器人的路径规划所作的准备.     

基于CATIA的工程图拼图打印管理系统

针对CATIA只能进行单张出图且无法对局域网内打印机进行交互管理的问题.提出了一种拼图算法,以CAA为开发工具对CATIA进行二次开发,实现CATIA平台上工程图的自动拼图以及对局域网内打印机进行交互管理.自动拼图模块提高了打印效率,节约纸张.打印管理模块使得局域网内的计算机实时和打印机进行交互,有利于用户进行工作的协同,提高工作效率.     

树脂基复合材料发动机机架结构研究

采用树脂基复合材料,对发动机执架的结构进行了设计,对结构进行了材料工艺及静强度试验研究.在设计分析的基础上,对纤维和树脂基体的筛选、优化进行了研究,对复合材料的基本力学性能和疲劳老化性能进行了研究.最后对大部件复合材料固化成型的工艺参数进行了优化,开展了机架结构连接方式和相关接头加工技术可行性研究.本文对树脂基复合材料在航天主承力结构上的应用进行了初步的探索和研究.     

基于模糊综合评估法的某综合信息系统评估

考虑到综合信息系统存在大量的模糊信息,很难用精确数学模型描述其内部关系,采用模糊综合评估法对其进行了评估.首先通过对综合信息系统的功能需求进行分析,建立了评估指标体系.然后介绍了确定指标权重的AHP法,并建立了对综合信息系统进行评估的模糊综合评判模型.最后通过实例对某装甲机械化部队综合信息系统进行了评估.     

半月板粘弹性实验研究

本文报道了作者对正常国人急性外伤致死的新鲜尸体半月板进行蠕变实验的结果.测定了半月板应力和时间相关的不同效应.用回归分析的方法对实验数据进行处理,得出了半月板归一化蠕变函数及曲线.并对实验结果进行分析讨论.     

Decrease in the operating gas pressure in an ion source

The results of use of a cold hollow cathode with a multipole magnetic field in a duoplasmatron-type ion source are described. The operating parameters of a duoplasmatron with the developed cathode and a duoplasmatron with a cold hollow two-cylinder cathode are compared. It is shown that the use of a cathode with a multipole magnetic field offers additional possibilities of reducing the operating gas pressure in an ion source and contributes to an increase in both the current and the phase density of the ion-beam current at the output of a charged-particle source and to a decrease in the phase volume of this beam.     

Robust scene recognition using a GA and real-world raw-image

This paper presents a new concept of scene recognition by a genetic algorithm (GA), using the 2-D gray-scale image of a working space, termed here as raw-image, and a model shaping the 2-D top-surface of a target object. In fact here, the problem of object recognition in the raw-image is changed into an optimization problem of a model-based evaluation function. We make use in this research of a GA, as a search and optimization method. This GA employs a model-based fitness function as its objective function to perform the search of a target in the raw-image. In this research, three object models, namely a frame model, a surface model, and a surface-strips model are investigated in order to determine which one is the best for scene recognition in a noisy environment. Also, in order to appraise the recognition performance of each model, a comparative study is performed by analyzing the answers to the following criteria questions: sensitivity, reliability, and speed. The effectiveness of the method has been verified through experiments using real-world raw-images, and the method has shown its robustness of object recognition with the surface-strips model, in spite of the noises in the scene.     

Calculation of the induction of a constant magnetic field created in a ferromagnet by an attachable electromagnet

On the grounds of the numerical calculation of the induction of a magnetic field excited in a ferromagnet by scanners in the form of Π-shaped and solenoidal electromagnets, it is established that the Π-shaped type provides a deeper penetration of a magnetic field into a ferromagnet and its better localization in a specified volume. The induction of a magnetic field appearing under the action of a Π-shaped scanner in a ferromagnet decreased with an increase in both the thicknesses of the ferromagnet and the gap between the magnetic conductor of a scanner and the surface of a material and also depended slightly on changes in its width; a maximal scanner winding current exists, above which the induction of a magnetic field in a material changes slightly.     

Reconstruction of flaw images by the C-SAFT method from echo signals measured by an antenna array in the triple-scanning mode

The application of antenna matrices (AMs) for obtaining flaw images during automated nondestructive ultrasonic testing is considered. The conventional technique of using an AM as a phased AM (PAM) has a number of drawbacks. One of them is related to the small number of AM elements and consists in a low frontal resolution of the thus-formed images. Scanning with an AM operating in the double scanning mode, viz., the so-called triple-scanning mode, allows coherent summation of partial images for each position and obtaining a resulting image with a frontal resolution that cannot be attained with a PAM. In order to test the serviceability of the proposed algorithm in the CIVA program, echo signals reflected from a crack model with a height of 6 mm and a length of 30 mm in a tested object, which simulated a welded joint of a pipeline with a conventional diameter of 800 mm (дy800), were calculated. The results of the reconstruction of images of model objects in the form of a drilled side hole with a diameter of 6 mm at a depth of 15 mm in a CO-2 specimen and a fatigue crack in a welded joint of a д y800 pipeline are presented. To reduce the influence of reverberation noise, a B-type median template was subtracted from echo signals. The flaw images that were reconstructed in numerical and model experiments demonstrate the efficiency of the proposed algorithm.     

Automated fixture configuration using projective geometry approach

The geometric and topological specification of a workpiece boundary is usually represented in a specific data format in a CAD database. To retrieve a set of workpiece data, to analyse its shape in addition to the machining requirements, and to determine the proper fixture configuration accordingly, are not trivial tasks when a part has a complicated shape. The real challenge is to recognise and synthesise the shape of a workpiece from its data representation. Consequently, the decision for fixturing can be made when the shape of a workpiece and the relationship of the shape and the fixturing configuration can be derived by a systematic methodology. In this paper, a projective spatial occupancy enumeration (PSOE) approach is applied as a representational and manipulating scheme for developing algorithms in automatic fixture configuration. The workpiece is projected onto the working plane of the fixture baseplate. A 2D projection is defined as a matrix of cells which can represent a workpiece with an arbitrary shape. Using a discrete search based upon the matrix of cells, the fixture types and their locations are generated according to a set of heuristic algorithms. This work is a generalisation and extension of previous works for prismatic parts. The same methodology is equally applicable in general robot grasping.     

Accretion of titanium carbide by electrical discharge machining with powder suspended in working fluid

A surface modification method by electrical discharge machining (EDM) with a green compact electrode has been studied to make thick TiC or WC layer. Titanium alloy powder or tungsten powder is supplied from the green compact electrode and adheres on a workpiece by the heat caused by discharge. To avoid the production process of the green compact electrode, a surface modification method by EDM with powder suspended in working fluid is proposed in this paper. After considering flow of working fluid in EDM process, the use of a thin electrode and a rotating disk electrode are expected to keep powder concentration high in the gap between a workpiece and an electrode and to accrete powder material on the workpiece. The accretion machining is tried under various electrical conditions. Titanium powder is suspended in working oil like kerosene. TiC layer grows a thickness of 150 μm with a hardness of 1600 Hv on carbon steel with an electrode of 1 mm in diameter. When a disk placed near a plate rotates in viscous fluid, the disk drags the fluid into the gap between the disk and the plate. Therefore, the powder concentration in the gap between a workpiece and a rotational disk electrode can be kept high. A wider area of the accretion can be obtained by using the rotational electrode with a gear shape.     

Engineering signal processing based on bistable stochastic resonance

The stochastic resonance (SR) characteristics of a single bistable system and two bistable systems connected in series with small and large parameters have been investigated, respectively. The viewpoint is that a single bistable system is better than a cascaded bistable system in detecting a weak periodic signal in frequency domain, and that, in time field, a cascaded system can detect a more beautiful waveform of either a periodic or an aperiodic weak signal. However, for some detection of a special signal, the periodic pulse for instance, a single bistable system is of great benefit to the signal extraction in time domain. It can provide some important information properties that are hardly obtained in frequency spectrum. Two examples of detecting a weak signal embedded in strong noise are presented in the end to illustrate that a single bistable system and a cascaded bistable system are both powerful tools for signal processing.     

A CO2 tracer-gas method for local air leakage detection and characterization

A method for local measurement of air leakage rate is presented that can be used to accurately and quickly assess leakage rates across a surface, such as around a valve or hatch in a pressurized gas tank or a window in a building. The method uses a small local enclosure with constant volume placed about a region on the structure under investigation (e.g., a window), which is depressurized and injected with a small concentration of carbon dioxide as a tracer gas. The time variation of the pressure and carbon dioxide concentration inside the enclosure are monitored and used to quantify the leakage flow rate as a function of pressure difference. This method uses a small enclosure with internal mixing so that a quasi-steady-state condition is quickly achieved. Because of the small size of the enclosure, advanced data processing techniques are necessary to reduce uncertainty in determination of the rate of change of the carbon dioxide concentration that arises from sensor variability. Results of a laboratory demonstration of the proposed leakage detection and characterization device are reported for the problem of leakage through a circular hole in a plate with prescribed pressure differences. Experimental results from the laboratory tests are found to be in excellent agreement with results of a numerical simulation of leakage flow through a hole, as well as predictions from a number of empirical equations for this problem found in the literature.     

Natural enamel caries in polarized light microscopy: differences in histopathological features derived from a qualitative versus a quantitative approach to interpret enamel birefringence

Lesion area measurement of enamel caries using polarized light microscopy (PLM) is currently performed in a large number of studies, but measurements are based mainly on a mislead qualitative interpretation of enamel birefringence in a single immersion medium. Here, five natural enamel caries lesions are analysed by microradiography and in PLM, and the differences in their histopathological features derived from a qualitative versus a quantitative interpretation of enamel birefringence are described. Enamel birefringence in different immersion media (air, water and quinoline) is interpreted by both qualitative and quantitative approaches, the former leading to an underestimation of the depth of enamel caries mainly when the criterion of validating sound enamel as a negatively birefringent area in immersion in water is used (a current common practice in dental research). Procedures to avoid the shortcomings of a qualitative interpretation of enamel birefringence are presented and discussed.     

A High-Power Semiconductor Generator for an Atomic Injector

An atomic injector with a beam power of 1 MW for heating plasma in the TCV tokamak (Lausanne, Switzerland) by a beam of neutral atoms was developed and put into operation in 2015–2016 at the Budker Institute of Nuclear Physics SB RAS (Novosibirsk). Plasma in the injector is formed in a plasma emitter by a high-frequency magnetic field, which is created by a high-power semiconductor generator with an output power of 40 kW at a frequency of 4 MHz. The facility operates in the pulse mode with a pulse duration of 2 s and a pause of 5 min. The generator is manufactured in the form of a modular system consisting of 16 identical generator modules, whose high-frequency power is summed, control modules, and a power-supply source. The generator allows modulation of the output power in the range of 30–100% by changing the power-supply voltage. The general structure of the generator and its elements and the results of its commissioning are presented.