弧面分度凸轮机构参数化设计与仿真

以弧面分度凸轮机构为研究对象，基于VC＋＋面向对象的方法及Pro／ENGINEER二次开发技术，建立了弧面分度凸轮参数化设计系统，该系统给出了界面友好的参数输入对话框，能够完成机构参数的自动综合和凸轮轮廓的自动生成，具有直观性、易于操作和调整，并在Pro／ENGINEER环境下进行装配、仿真与干涉检测，验证了设计的合理性。     

一种柔性的注塑模热流道设计系统

目前注塑模热流道设计中存在设计工作量大、自动化程度不高的问题。针对复杂形状的分流板,提出了一种基于草图特征拼合的设计方法。该方法将分流板实体特征分解为对应的参数化草图特征,通过草图特征的参数化绘制和自动剪切,完成草图的绘制,并生成分流板零件。此外通过建立装配规则,实现了热流道配件的自动装配。该系统在SolidWorks平台下开发,实际应用表明该系统兼具效率和柔性,适用于复杂的热流道系统的设计。     

基于FFD与网格自动重构的吹膜风环出口位置及轮廓优化设计

为了提高薄膜吹塑过程中的膜泡冷却效率与稳定性,基于自由变形与网格重构技术,建立自动仿真流程,利用全局优化算法实现对吹膜风环出口位置及轮廓的优化设计。使用FFD自由变形技术对单口风环出口轮廓进行参数化设计;以初始几何离散点作为输入量,通过B样条曲线插值、计算域分块、子块网格划分与拼接,实现计算域网格自动重构;采用拉丁超立方抽样获取初始样本集,根据样本及对应响应值建立代理模型,基于代理模型建立全局优化算法,对风环出口位置及轮廓进行优化设计。结果表明,优化后的风环改变了冷却空气到达膜面的方式,在维持同水平冷却效率的同时,膜泡外表面静压差值降低60%,膜泡稳定性得到改善。     

基于模糊神经网络滑模控制的xy平台轮廓控制

永磁同步直线电机(PMLSM)直接驱动xy平台数控系统曲线轨迹跟踪时,其轮廓精度会受负载扰动以及曲线轨迹轮廓误差模型复杂等问题的影响。针对此问题,采用具有自学习能力的模糊神经网络滑模控制(FNNSMC)进行单轴位置控制器的设计,在不失滑模控制鲁棒性的情况下,有效地削弱该控制所产生的抖振;两轴之间运用实时轮廓误差计算法建立曲线轨迹的轮廓误差模型并采用交叉耦合控制(CCC)进行轮廓控制器的设计,实现跟踪误差与轮廓误差的同时减小。仿真结果表明:该控制方案基本消除了抖振,保证xy平台具有较强的鲁棒性和较高的轮廓精度。     

基于极坐标法的直线电机XY平台轮廓控制

对于直线电机驱动XY平台,非线性的系统动态、曲线轨迹的轮廓误差模型相对复杂以及传统控制无系统化参数调整规则等问题影响其轮廓加工精度.采用适用于非线性运动系统轮廓控制的极坐标法,建立可用于一般曲线且容易计算的直线电机XY平台极坐标误差非线性模型,使轮廓控制问题转换为稳定化的问题.对非线性误差动态模型进行反馈线性化处理后设计状态反馈控制器,使轮廓误差趋近于零.理论推导与仿真结果表明所设计控制系统能有效提高直线电机XY平台的轮廓加工精度.     

基于等效误差法的直线电机XY平台轮廓控制

对于直线电机驱动XY平台,非线性的系统动态、曲线轨迹的轮廓误差模型相对复杂以及传统控制无系统化参数调整规则等问题影响其轮廓加工精度.采用适用于多轴非线性运动系统轮廓控制的等效误差法,建立可用于一般曲线且容易计算的XY平台等效误差非线性模型,使轮廓控制问题转换为稳定化的问题.对非线性误差动态模型进行反馈线性化处理后设计状态反馈控制器,使轮廓误差趋近于零.理论推导与仿真结果表明所设计控制系统能有效提高XY平台的轮廓加工精度.     

基于H∞反馈的直接驱动XY平台切向轮廓控制设计

为了提高XY平台的轮廓加工精度,在分析系统轮廓误差的基础上,提出将H∞速度反馈控制器和切向-轮廓控制器(TCC)相结合的控制策略.在速度环内采用H∞鲁棒控制理论设计反馈控制器,在具有模型摄动及外部干扰的情况下,保证了闭环系统的鲁棒稳定性和鲁棒性能,TCC使得XY平台之间的耦合作用消除,且轮廓控制器设计变得更加直接和简单.单轴系统采用IP(积分-比例)控制与速度前馈控制相结合的复合控制器.仿真结果表明所设计控制系统在保证具有较好的跟踪性能、鲁棒性能的同时轮廓精度大大提高.     

一种基于二维草图的三维CAD模型检索方法

提出一种基于二维草图的三维CAD模型检索方法,通过比较三视图草图和CAD模型三视图来实现模型的检索.首先提取模型库中CAD模型的三视投影图,然后利用联合描述子方法对用户绘制提交的二维三视图草图和CAD模型的三视投影图进行相似性评价,实现模型的检索.实验结果表明,文中方法具有较好的检索性能,检索结果能更好地反映用户的检索意图.     

详解摆线轮磨削软件与数控系统的关联

对于具有复杂曲面轮廓的RV减速器摆线轮的制造,通过辅助制造软件对齿廓进行设计和修形并根据最终齿廓曲线自动生成G代码数控程序通过数控系统直接读取加工,可以减轻工人的编程工作量,提高生产效率。     

浅析建筑设计对抗震设计的重要性

基于建筑设计中的抗震设计问题,阐述了建筑设计中抗震与隔震的基本设计概念,探讨了建筑方案设计阶段及建筑施工图设计阶段的抗震与消能减震设计的重要性及直接的控制作用。     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

INTRODUCTION TO PATENTS

The invention provides a method of making a mold which can reduce SOx generation rate while preventing decrease in hardening rate in the case of using sulfuric acid for a hardener composition. The method has a mixture step in which fire-resistant particles, a hardener composition and a binder composition are mixed to obtain a composition for a mold. The hardener composition contains sulfuric acid. In the mixture step, sodium carbonate is added. A molar ratio of the sulfuric acid to the sodium carbonate is 0.5 or more and 4.0 or less.     

China Foundry Week 2014

China Foundry Week, hosted by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） each year, is a large academic event in China. It is one of the ten high-impact activities sponsored by the Chinese Mechanical Engineering Society.     

17th Conference of Hydrodynamic and Electromechanical Control Engineering Call for papers

正1.Contents In order to promote the academic exchanges and technical communication of the research in the field of fluid power transmission and control,fluid control engineering specialized committee of the Chinese Society of Theoretical and Applied Mechanics will hold the 17th Conference of Hydrodynamic and Electromechanical Control Engineering on July 27-29,2014 in Tibet,Lhasa city.     

Information for Contributors

正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis     

Preface

<正>We are pleased to present this Special Issue of Transactions of Nonferrous Metals Society of China containing selected papers from the First Asian Conference on Aluminum Alloys(ACAA-2013),held in Beijing,China,13–17 October 2013.This conference has been initiated,with approval of     

Information for Contributors

The Transactions of Nonferrous Metals Society of China, founded in 1991 and sponsored by The Nonferrous Metals Society of China, is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology, including mineral processing, extraction metallurgy, metallic materials and heat treatments, metal working, physical metallurgy, powder metallurgy, with the emphasis on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, 1NSPEC, CA, METADEX, AJ and JICST.     

Formulas of Tension of Continuous Rolling Process

The development of computer controlled continuous rolling process calls for a mathematical expression that can express the inequality condition of "constant flow". Tension is the link of the continuous rolling process. From the condition of dynamic equilibrium, a differential equation of tension is given out. On the basis of the physical rules established from the industrial practice and experimental studies, the law of volume constancy, the linear relation of forward slip and tension, the state equation of continuous rolling, the formula of dynamic tension, and the formula of static tension have been obtained. These formulae reflect the functional relations between tensions, thickness, roll velocity, and time in the continuous rolling process. It is implied that the continuous rolling process is a gradually steady, controllable, and measurable dynamic system. An assumption of predicting the thickness of a steel plate using these tension formulae is also put forward.