Review of Determination of Minimum Ignition Energy of Combustible Gases or Dusts

MIE is an important parameter to be used to rank the ignition risk of the combustible materials.Commonly used electric circuits for generating spark have been reviewed and their features are analyzed in detail.Attention to avoiding test errors is stressed.Ranking of ignition risk is suggested based on MIE data.     

NCI-MS／MS检测复杂样品中微量TNT成分

The method of use NCI-MS/MS to detect TNT is sensitive and selective. It can be used to detect trace TNT in complex sample and it is useful to analyze the sample collected from scene.     

MEASUREMENT OF 2-DIMENSIONAL DISPLACEMENT USING 2-D ZERO-REFERENCE MARKS

Several 2-D displacement sensing methods are reviewed. As to the cross diffraction grating, there is no absolute zero-reference. In regards to the optical fiber method, the output signal is affected greatly by the quality of the reflecting surface and it is hard to get high resolution. Considering the concentric-circle gratings, the displacement can only be gained with complicated calculating of the experiment data. Compared with the advantages and limitations of the methods above, a novel 2-D zero-reference mark is especially proposed and demonstrated. This kind of mark has an absolute zero-reference when used in pair, and the experimental result is simple to dispose. By superimposing a pair of specially coded 2-D marks, the correct alignment position of the two marks can be detected by the maximum output of the sharp intensity peak. And each slope of the peak is of good linearity which can be used to achieve high resolution in positioning and alignment in two dimensions. Design and fabrication of such     

PRODUCT DATA PREDICTION WITH UNCERTAINTY IN PRODUCT LIFE CYCLE DESIGN

Various kinds of data are used in new product design and more accurate data make the design results more reliable. Even though part of product data can be available directly from the existing similar products, there still leaves a great deal of data unavailable. This makes data prediction a valuable work. A method that can predict data of product under development based on the existing similar products is proposed. Fuzzy theory is used to deal with the uncertainties in data prediction process. The proposed method can be used in life cycle design, life cycle assessment (LCA) etc. Case study on current refrigerator is used as a demonstration example.     

The improved open mill

Open type rubber mixing machine is referred to as open mill which one of the basic equipment for the rubber products processing. Double roller open mill was used in the production of rubber processing in 1824; it has been 180 years of history and is still in use now. As the open mill is not restricted from the height of the plant, so it has various functions of rubber mixing alone and hot mixing, it can be formed a linkage production line with mixer through the open mill to be added with curing ingredient, which making it has been extensive attention in the rubber industry and widespread used.     

Finite Element Analysis of the Dynamic Behaviour of Transmission Line Conductors Using MATLAB

The dynamic behaviour of power line cables have been a source of interest to researchers ever since the phenomenon was first noticed in the 1920s. Conductor oscillation is mostly caused by the dynamic forces of nature such as wind loading. This imposes a periodic force on the conductors which is highly undesirable. It is therefore important for engineers to account for the possible effect of the wind loading when designing the power line. Investigations have shown that modeling the exact dynamic behaviour of a conductor is very difficult. Based on this fact, getting the exact analytical solution to conductor vibration is difficult, which is almost impossible, hence the numerical approximation becomes an option. This paper presents the developed finite element method used to analyse the dynamic behaviour of transmission line conductors. The developed FEM （finite element method） is implemented on MATLAB. The numerical analysis using MATLAB that is presented in this paper is used to simulate the response of the conductor when subjected to external loading in the time domain. The simulation is used to analyse the transverse vibration of the conductor. The formulation of the stiffness matrix and load vector is done and the results obtained are used to evaluate the conductor＇s internal energy dissipation. This finite element solution is compared with the results documented in literature. This numerical simulation is also used to investigate the effects of varying the axial tension on energy dissipation within the strands. Hence, this evolved in physically appropriate energy characterization process that can be used to evaluate the conductor self-damping with respect to line contact.     

Brief introduction of current status domestic blow moulding machine

Blow molding is a commonly used method which manufacture of hollow thermoplastic products, the main products are film blowing machine and hollow container. Blow molding machine can be heated so that made pre-molding plastics products to plasticate , and then blown into molding, this method is mainly used for high-speed, high-volume production of PET and BOPP bottles, that is two-step process; blow molding and injection molding can also be combined into all-inones injection stretch blow machine, which is a commonly used methods in the production of PET container; blow molding process can also be combined with the extrusion process, extrusion blow molding equipment adapt to a wider range, which can produce the product more enrich, including multi-layer compound films and various types of polyolefin hollow container widely used in foodstaff, pharmaceutical and cosmetics industries.     

TWO-STAGE OCCLUDED OBJECT RECOGNITION METHOD FOR MICROASSEMBLY

A two-stage object recognition algorithm with the presence of occlusion is presented for microassembly. Coarse localization determines whether template is in image or not and approximately where it is, and fine localization gives its accurate position. In coarse localization, local feature, which is invariant to translation, rotation and occlusion, is used to form signatures. By comparing signature of template with that of image, approximate transformation parameter from template to image is obtained, which is used as initial parameter value for fine localization. An objective function, which is a function of transformation parameter, is constructed in fine localization and minimized to realize sub-pixel localization accuracy. The occluded pixels are not taken into account in objective function, so the localization accuracy will not be influenced by the occlusion.     

SIMUUTION OF ELECTROMAGNETIC TUBE BULGING BASED ON LOOSE COUPLING METHOD

A loose coupling method is used to solve the electromagnetic tube bulging. ANSYS/ EMAG is used to model the time varying electromagnetic field with the discharge current used as excitation, in order to obtain the radial and axial magnetic pressure acting on the tube, the magnetic pressure is then used as boundary conditions to model the high velocity deformation of tube with DYNAFORM. The radial magnetic pressure on the tube decreases from the center to the tube end, axial magnetic pressure is greater near the location equal to the coil height and slight in the other region. The radial displacement of deformed workpieces is distributed uniformly near the tube center and decreases from the center to the end; Deformation from the location equal to coil height to the tube end is little. This distribution is consistent with the distribution of radial pressure; Effect of the axial magnetic pressure on deformation can be ignored. The calculated results show well agreements with the experimental results.     

轮廓度公差控制车身装配间隙的图样标注研究

针对如何使用轮廓度公差控制汽车装配间隙及其均匀性时的图样标注问题,首先以汽车前后车门装配为例分别研究了复合轮廓度和附加“OZ”符号的组合轮廓度在控制装配间隙时的图样标注和应用特点。其次,以面板和按钮装配为例研究了复合轮廓度和附加“OZ”的组合轮廓度在控制半封闭轮廓装配间隙及其均匀性方面的差异,指出对于封闭/半封闭或曲率较大轮廓之间的间隙控制,标注附加“OZ”的组合轮廓度比复合轮廓度更合理。最后,分析了带“OZ”的组合轮廓度公差在封闭轮廓-汽车油箱盖与车身装配间隙控制的图样标注及检测。研究结果可为车身装配间隙及均匀性公差控制时的图样标注提供借鉴和参考。     

高体积分数SiC/Al焊接结构应用于空间相机的稳定性研究

针对焊接工艺应用于高体积分数SiC/Al复合材料的不成熟性研究了焊接工艺应用于航天遥感器机身结构的的稳定性。根据光学设计公差分析结果和机身的结构形式,提出了通过运用经纬仪和三坐标测量机测量角量和线量的验证原理,论证了胶接工艺的可行性。对机身进行了热循环试验,标定了实验前后各测点的角度以及距离,对实验前后的数据进行了比较。结果表明,机身最大转角俯仰方向为2.1″,方位方向为2.3″,机身三个方向的最大距离变化分别为0.034mm,0.044mm,0.034mm,焊接工艺应用于高体积分数SiC/Al复合材料,能够满足设计指标为转角小于5″,距离公差±0.05mm的设计要求。     

基于Pro/E的公差分析在天线结构设计中的应用

公差分析是结构设计中的重要部分,公差分析方法分为极值法和统计法两类.文中介绍了两类公差分析方法,利用Pro/E的公差分析对产品装配的公差进行分析,并对相关零件公差进行评估和优化.分析结果表明,Pro/E的公差分析功能为产品设计的改进指出了方向,相比传统的经验设计,效率更高,对提高产品质量和降低产品成本有着明显的应用价值.     

坐标缩放激光角谱传输及在激光光学系统中的应用

提出了坐标可缩放的激光传输角谱算法,用于评估激光光学系统性能并分析其系统公差。考虑Collins公式可用于计算激光光束在光学系统中的衍射传输过程,对该积分公式进行了坐标代换,将衍射积分公式转换为角谱传输过程,并引入坐标缩放因子,实现了目标面尺寸的自由选择,提高了激光传输计算的准确性。设计了一套激光传输系统,定义占有86.5%桶中功率的光斑尺寸为光斑半径,用提出的算法对激光光束传输公差进行了分析。分析表明:作用距离为90m时,焦面激光光斑的半径为0.8~1.4mm,期望值为0.92mm,实验测量值为1.01mm;作用距离为49m时,焦面激光光斑的半径为0.42~0.73mm,期望值为0.48mm,实验测量值为0.46mm,实验结果与公差分析相符。另外,通过公差分析验证了激光光束在光学系统中的焦移现象。由角谱法对激光传输系统的理论分析与实验结果相符,证明了该方法用于激光聚焦光学系统设计的可行性。     

Seam gap bridging of laser based processes for the welding of aluminium sheets for industrial applications

Laser welding has a large potential for the production of tailor welded blanks in the automotive industry, due to the low heat input and deep penetration. However, due to the small laser spot and melt pool, laser-based welding processes in general have a low tolerance for seam gaps. In this paper, five laser-based welding techniques are compared for their gap bridging capabilities: single-spot laser welding, twin-spot laser welding, single-spot laser welding with cold wire feeding, twin-spot laser welding with cold wire feeding and laser/GMA hybrid welding. Welding experiments were performed on 1.1- and 2.1-mm-thick AA5182 aluminium sheets. The resulting welds were evaluated using visual inspection, cross sectional analysis with optical microscopy, tensile tests and Erichsen Cupping tests. The results show that the use of a filler wire is indispensable to increase the gap tolerance. A proper alignment of this wire with the laser spot(s) is crucial. With the single spot laser welding with cold wire feeding, a gap up to 0.6 mm could be bridged as opposed to a maximum allowable gap width of 0.2 mm for single-spot laser welding without filler wire. For 2.1-mm-thick sheets, the laser/GMA hybrid welding process can bridge even gaps up to 1.0 mm. Most welds had a high tensile strength. However, during Erichsen Cupping tests, the deformation of the welds is significantly lower as compared to the base material.     

Study of laser butt welding of SUS301L stainless steel and welding joint analysis

This paper describes a study on laser butt welding of 4 and 2 mm SUS301L stainless steel and a detailed analysis of welding joints. The gap tolerance of butt joint was also studied with optimized process parameters. The electrolytic etching in 10 % oxalate solution was used to test the intergranular corrosion of the 4 mm SUS301L welded joint. Fatigue property of the 2 mm SUS301L welded joint was tested under the conditional cycle times of 1?×?10⁷. Using optical microscopy, the changes of metallurgical microstructure in the weld zone of 4 mm SUS301L were also studied. It has been found that laser butt welding of 4 mm SUS301L is able to achieve sound metallurgical morphology and high strength weld joint when the butt gap is within certain tolerance. The weld joint also has good resistance to intergranular corrosion and has a fatigue limit of 310 MPa.     

基于容差分析的结构非概率可靠性模型

在对新结构进行可靠性设计分析时,概率可靠性模型和模糊可靠性模型对数据信息要求较高。为了充分利用结构的不确定性信息以弥补数据的不足,在采用区间变量描述结构不确定性参数的前提下,研究不确定性参数的容差与偏差之间的关系及其对结构可靠性的影响方式,提出一种基于容差分析的结构非概率可靠性模型。进而,以结构应力—强度干涉模型为基础,分析结构的典型干涉模式与不确定性参数容差的存在性质,给出结构非概率可靠性的一种新的度量方法。以简单线性结构为例给出相应的算法,并将此推广到非线性结构。接着以多变量线性结构为例,给出相应算法,并同样将其推广到非线性结构。该方法适用于任意形式的结构功能函数,计算简便,易于工程实现,为结构容差设计与可靠性分析提供定量依据。     

0.5×～2.5×长工作距离变焦距显微物镜设计

根据变焦距理论和显微物镜的特点,利用Zemax设计了一款可连续变倍的显微物镜。该物镜由4组双胶合透镜组构成,结构简单,成像质量良好,变倍范围在0.5~×~2.5~×之间,最大数值孔径达到0.1,共轭距346mm,物距76mm,空间频率65lp/mm处,全视场内的调制传递函数均大于0.3,适用于可见光光谱,可以与1/2inch CCD相匹配。通过对所设计的变倍显微物镜进行公差分析,得到一套比较宽松的公差,适合批量生产。设计结果表明,该变倍显微物镜可以满足工业视频检测的要求。     

The Noded graph approach to stack analysis

The tolerance chart is a graphical method for representing the manufacturing dimensions of a workpiece or assembly, at all stages of its manufacture. The chart provides an intermediate control system of checks and balances to ensure that processing dimensions and tolerances will meet those specified on the print. Tolerance charts are generally used in studying the dimensional problems on individual parts. However, they have proved tedious in their application to assemblies. This paper presents a simple and systematic approach to the process of tolerance stack analysis. The Noded graph model is constructed, representing the given and the unknown dimensions. Links are then established, using the model, which help to formulate the stack path of interest into a linear equation. The equation is used to complete the tolerance stack analysis module. This will be explained using a variety of geometric dimensioning and tolerancing examples. In addition, it is simple and hence easy to practise and very logical.     

Experimental and Simulation Studies on Cold Welding Sealing Process of Heat Pipes

Sealing quality strongly affects heat pipe performance, but few studies focus on the process of heat pipe sealing. Cold welding sealing technology based on a stamping process is applied for heat pipe sealing. The bonding mechanism of the cold welding sealing process (CWSP) is investigated and compared with the experimental results obtained from the bonding interface analysis. An orthogonal experiment is conducted to observe the effects of various parameters, including the sealing gap, sealing length, sealing diameter, and sealing velocity on bonding strength. A method with the utilization of saturated vapor pressure inside a copper tube is proposed to evaluate bonding strength. A corresponding finite element model is developed to investigate the effects of sealing gap and sealing velocity on plastic deformation during the cold welding process. Effects of various parameters on the bonding strength are determined and it is found that the sealing gap is the most critical factor and that the sealing velocity contributes the least effect. The best parameter combination (A ₁ B ₃ C ₁ D ₃, with a 0.5 mm sealing gap, 6 mm sealing length, 3.8 mm sealing diameter, and 50 mm/s sealing velocity) is derived within the experimental parameters. Plastic deformation results derived from the finite element model are consistent with those from the experiment. The instruction for the CWSP of heat pipes and the design of sealing dies of heat pipes are provided.