电器外壳的PTC/Creo体积块快速分模技术

根据电器外壳的几何结构特点,运用PTC/Creo软件的聚合体积块工具创建模具型芯中的体积块,并以拔模方式偏移体积块曲面形成外壳中的5个切口卡扣靠破孔的分型面,再通过草绘体积块方法分别完成模具型芯分型体积块与2个侧向滑块体积块的设计,简化模具分型面的设计过程,展示体积块工具的使用方法,为实现相似卡扣靠破孔分型面与模具分模设计提供了快速解决方案。

电器外壳模具的PTC/Creo阴影曲面分模技术应用

以电器外壳的模具设计为例,运用PTC/Creo软件的"阴影曲面"工具,通过定义滑块体积块作为"阴影闸板"选项的参照,根据初始阴影曲面中的切口卡扣的自相交内环边界,添加阴影零件中的5个切口直立侧面一定的拔模斜度,使其满足阴影曲面的创建条件,实现模具体积块的设计,再通过拔模以恢复模具型芯体积块中对应于切口的直立侧面,达到符合模具零件的设计要求,为拓展阴影曲面技术的使用方法和分模设计提供了一定的参考。

基于Pro/E的注射模分模技术

介绍了在Pro/E中进行注射模设计的一般流程,详细讲述了分模的步骤和方法,包括一般分型面和特殊分型面的创建方法,模具体积块的分割和创建方法。

基于Cimatron E的壳体塑件快速分模技术的应用

通过对壳体塑件产品进行了分析,介绍运用Cimatron E软件进行塑件快速分模的基本流程,对脱模方向的自动确定、分型线和分型面的生成方法进行了分析,并对快速分模技术的应用进行了总结。

基于Cimatron E快速分模技术的研究与应用

模具设计中的分模工作繁重而关键。在探讨基于Cimatron E的快速分模技术的过程中,同时完成了充电器上壳的分模任务,非常简捷地获得其型腔、型芯、侧抽等模具镶块。借助快速分模技术大大简化了分模工作量及提高了模具设计的效率。

塑胶模模仁的分模技术分析

文章就塑胶模模仁的分模问题展开详细论述,详细介绍了塑胶模分模的概念,阐述了塑胶产品主、副模模具的确定方法,塑胶产品拔模角度对模具的影响及塑胶产品的圆角处分模方法,在靠破、插破和入子等方面提出了较完整的解决方案,为塑胶模模仁的分模技术提供了实用的设计基础。

照相机前盖多腔模的PTC/Creo体积块快速分模技术研究

运用PTC/Creo软件的模具体积块方法,以照相机前盖多腔模布局节点中第一个参照模型作为设计的参照,分别完成其破孔分型体积块、枕位体积块与镶件体积块或分型体积块的设计,并创建体积块的组特征及其"参照"类型的阵列,成功实现了多腔模布局中其他参照模型相应体积块的设计,达到简化模具分模进程的目的。该技术演绎了模具体积块在多腔模分模设计中的功能特点与使用方法,提升了模具的设计水平,从而为快速实现多腔模布局的分模设计提供了全新的解决方案。

柔性可收分提模技术

结合具体工程实例,介绍了柔性可收分提模技术的工艺原理和施工流程,具体阐述了收分模板制作,提模装置设计,收分模板安装等操作要点和注意事项,并对材料,机具设备,质量要求,安全措施分别作了说明,指出该技术优点众多,具有广泛的应用前景。

Measuring technical efficiency of Chinese nonferrous metals enterprises on a background of industry consolidation

Since 2009, Chinese nonferrous metals industry has been carried out industry consolidation with strong support by the central government. This work examined technical efficiency of Chinese nonferrous metals firms and its change during the period of 2007 and 2011. Based on financial data from nonferrous metals listed companies, technical efficiency of nonferrous metal minerals mining firms and nonferrous metal smelting, pressing and processing firms was estimated respectively using the data envelopment analysis （DEA） method. It was found that, in both sectors, number of pure technical and scale inefficient firms dominated over efficient ones. Overall, their technical and scale efficiency tended to be very low after 2009. In particular, efficiency scores of nonferrous metal smelting, pressing and processing firms fluctuated greatly during the research period. And a limited number of large leading firms were able to maintain 100% efficiency score in the industry, while efficiency of most of other leading firms has declined since 2009.

Classification of Chinese Traditional Drug-"Beimu" (Bulbus Fritillariae) by Pyrolysis High Resolution Gas Chromatography-Pattern Recognition

The combination of pyrolysis high resolution gas chromatography and pat- tern recognition techniques is a powerful tool for the classification of traditional Chinese drug.A study has been completed on 55 Beimu samples of five different geographic origins: Eastern China.Central China.South-western China,North-western China and North-eastern China.Principal component analysis and SIMCA are applied to effectively classifying the samples according to the origin of the plants.The chemical information contained in the high resolution gas chromatographic data is sufficient to characterize the geographic origin of sam- pies.

一种提高信息传输密度的新方法研究

推导了具有轨道角动量的拉盖尔—高斯光束的产生和检测方法,并在此基础上搭建了一个实验系统,利用不同轨道角动量量子数的拉盖尔—高斯光束作为相互正交的信息传输通道,验证了提高信息传输密度的可能性。还构成了模分复用技术的概念。实验表明,其传输通道间的影响比较小,合理地选择通道个数和小孔光阑的直径可以在降低互扰的同时成倍地提高信息传输密度。

J2EE-BASED DISTRIBUTED AND INTEGRATABLE MANUFACTURING EXECUTION SYSTEM

Using the Java 2 enterprise edition (J2EE), the industry standard technique, a component and web-based manufacturing execution system (MES), is presented. It is considered to be open, modularized, distributed, configurable, interoperable and maintainable. After introducing some core techniques of J2EE as the basic foundations of the proposed MES, this paper briefly analyzes the MES domain in manufacturing systems and constructs the abstract object and component model, and then establishes the MES architecture. This MES can be facilely integrated with other manufacturing applications. Finally, an example of integration with the enterprise resource planning (ERP) system is given.

Numerical Approach to the Mechanism of Cellulose Pyrolysis

A detailed mechanism analysis of cellulose pyrolysis was carried out according to the previous experimental results. On the basis of the Brodio-Shafizadeh model, a modified two-stage model was proposed to simulate the formation and decomposition of active cellulose (AC) and several main organic compounds, such as levoglucosan (LG), hydroxyl-acetaldehyde (HAA), acetol and furfural etc. During pryolysis, the temperature rise of cellulose can be divided into three stages. In the second stage, cellulose undergoes a main decomposition process in which the reaction temperature remains rather low because of the endothermic cracking of glucosidic bond of AC during the formation of LG. The components density of bio-oil, including LG and other competitive compounds, increased rapidly with the increase of temperature during the first stage. However, in the main decomposition process, LG density in bio-oil had an obvious decrease, while the competitive products appeared to increase gradually, which means the ring-opening and reforming reaction of pyranoid ring are superior to LG formation in high temperature.The secondary reaction of volatile components occurs largely in gaseous phase rather than in the solid phase. Short residence time of volatile materials in high temperature region will be advantageous to a high production of LG,which may otherwise decompose quickly under high temperature. An optimum yield of LG could be obtained when radiant source temperature is in the range of 730---920K and gas residence time is less than 1 s. In addition, the reaction temperature has a stronger effect than gas residence time on the formation of HAA, acetol, formaldehyde and furfural etc.

Simulation and analysis of resin flow in injection machine screw

A method with simulation and analysis of the resin flow in a screw is presented to ease the control of some problems that may affect the efficiency and the quality of the product among existing screws in an injection machine. The physical model of a screw is established to represent the stress, the strain, the relationship between velocity and stress, and the temperature of the cells. In this paper, a working case is considered where the velocity and the temperature distributions at any section of the flow are obtained. The analysis of the computational results shows an ability to master various parameters depending on the specifications.

Application of the Nutrient Cycling Model NuCM to a Forest Monitoring Site Exposed to Acidic Precipitation in China

The nutrient cycling model NuCM is one of the most detailed models for simulating processes that influence nutrient cycling in forest ecosystems. A field study was conducted at Tieshanping, a Masson pine (Pinus massoniana Lamb.) forest site, in Chongqing, China, to monitor the impacts of acidic precipitation on nutrient cycling. NuCM simulations were compared with observed data from the study site. The model produced an approximate fit with the observed data. It simulated the mean annual soil solution concentrations in the two simulation years, whereas it sometimes failed to reproduce seasonal variation. Even though some of the parameters required by model running were measured in the field, some others were still highly uncertain and the uncertainties were analyzed. Some of the uncertain parameters necessary for model running should be measured and calibrated to produce a better fit between modeled results and field data.

Hierarchical closed form solutions for plates bent by localized transverse loadings

3D and 2D closed form plate models are here applied to static analysis of simply supported square isotropic plates. 2D theories are hierarchically classified on the basis of the accuracy of the displacements and stresses obtained by comparison to the 3D exact results that could be assumed by the reader as benchmark for further analyses. Attention is mainly paid on localized loading conditions, that is, piecewise constant load. Also bi-sinusoidal and uniformly distributed loadings are taken into account. All of those configurations are considered in order to investigate the behavior of the 2D models in the case of continu- ous/uncontinuous, centric or off-centric loading conditions. The ratio between the side length a and the plate thickness h has been assumed as analysis parameter. Higher order 2D models yield accurate results for any considered load condition in the case of moderately thick plates, a/h=10. In the case of thick plates, a/h=5, and continuous/uncontinuous centric loading conditions high accuracy is also obtained. For the considered off-centric load condition and thick plates good results are provided for some output quantities. A better solution could be achieved by simply increasing the polynomial approximation order of the axiomatic 2D displacement field.

Molecular Simulation Study on Interaction of Thiophene Sulfides with Transition Metals

The computer molecular simulation technique was applied to study the chemisorption of thiophene and tetramethylthiophene as the model sulfides on the simple oxides and complex oxides of some transition metals as the catalytic materials. The study disclosed that the thiophene sulfides could enter into chemisorption with metal oxides such as VO, ZnO, NiO and Zn-Al-spinel. This interaction could lead to thiophene molecular structure deformation to be in an activated adsorption state, which could help to promote the conversion of thiophene sulfides in the course of catalytic cracking. The VO with a valence of 2 could provide relatively strong selective adsorption sites for the conversion of thiophene sulfides to apparently transform the molecular structures and electron cloud states of such heterocyclic sulfur compounds such as thiophene and tetramethylthiophene into an activated adsorption state. The effect of this interaction was more pronounced with respect to tetramethylthiophene.

Analysis of Single-Walled Carbon Nanotubes Using a Chemical Bond Element Model

A three dimensional nano-scale finite element model （FEM）, called the chemical bond element model, is proposed for the simulation of mechanical properties of single-walled carbon nanotubes （SWCNTs） based upon molecular mechanics method. Chemical bonds between carbon atoms are modeled by chemical bond elements. The constants of a sub-stiffness matrix are determined by using a linkage between molecular mechanics and continuum mechanics. In order to evaluate the correctness and performance of the proposed model, simulation was done to determine the influence of nanotube wall thickness, radius and length on the elastic modulus （Young＇s modulus and shear modulus） of SWCNTs. The simulation results show that the choice of wall thickness significantly affects the Young＇s modulus and shear modulus. The force field constants is also very important, because the elastic modulus is sensitive to force field constants and the elastic properties of SWCNT are related to the radii of the tubes. The contribution of length to elastic modulus is insignificant and can be ignored. In comparison with the Young＇s modulus and shear modulus reported in the literature, the presented results agree very well with the corresponding theoretical results and many experimental measurements. Furthermore, if the force constants are properly chosen, the present method could be conveniently used to predict the mechanical behavior of other single-walled nanotubes such as boron nitride nanotubes. The results demonstrate the value of the proposed model as a valuable tool in the study of mechanical behaviors of carbon nanotubes and in the analysis of nanotube-based equipments.

Experimental and simulation of the reactive dividing wall column based on ethyl acetate synthesis

Reactive dividing wall column(RDWC) is a highly integrated unit which combines reaction distillation(RD) with dividing wall column separation technology into one shell, and it realized the chemical reaction and the separation of multiple product fractions simultaneously. In this paper, the reaction of esterification with acetic acid and ethanol to produce ethyl acetate was used as the research system, experiments and simulations of the RDWC were carried out. This system in the traditional process mostly used the homogeneous catalyst(e.g. sulfuric acid). However, in view of the corrosion of the equipment caused by the acidity of the catalyst, we used the heterogeneous catalysts – iron exchange resins – Amberlyst15 and proposed a novel catalyst loading method. Firstly,the reliability of the model of the simulation was verified by the experimental study on the change of liquid split ratio and reflux ratio. After that, the four-column model was established in Aspen Plus to analyze the effects of the amount of azeotropic agent, reflux ratio and acetic acid concentration. Finally, for a fair comparison, the economic analysis was conducted between traditional RD column and RDWC. The results showed that RDWC can save34.7% of total operating costs and 18.5% of TAC.

Cold Model Study and Commercial Test on Novel Vapor-Liquid Distributor of Hydroprocessing Reactor

A novel vapor-liquid distributor was developed on the basis of sufficient study on the existing distributors applied in hydroprocessing reactors. The cold model test data showed that the fluid distribution performance of the novel vapor-liquid distributor was evidently better than the traditional one. Com- mercial tests of the new distributor were carded out in the 300 kt/a gas oil hydrotreating reactor at SINOPEC Changling Branch Company, showing that the new vapor-liquid distributor could improve the fluid distribution, promote the hydrotreating efficiency and lead to better performance than the traditional one.