DSP+FPGA数据处理系统的研究与应用

针对铣削加工中心主轴刚度检测系统实时性的要求,重点阐述了DSP FPGA的数字硬件系统和流水线结构的CORDIC算法在FPGA中的实现,并通过仿真和实验对CORDIC算法的理论值和计算数值进行对比分析,结果表明,计算数值非常接近理论值.     

美国流体动力工程研究中心简介

本文简要介绍了美国国家流体动力工程中心的基本情况、研究方向和教学计划.在此基础上对我国流体动力传动与控制的科研单位和企业的发展提出了一些看法.     

增量式旋转轴定向的应用实例

绝对值编码器能够准确地保持坐标位置,因此在需要定位或定向时常选用这种编码器.但某些时候由于改造的机械或者资金情况的限制只能使用增量式编码器,文中旨在讨论在这种情况下如何实现旋转轴的定向和定位.     

船舶ERP选型:集成性是关键

当前,信息化已经渗透到世界船舶工业的设计、生产、管理、服务等方方面面,其应用的深度与广度决定了行业综合水平的高低,成为大至一个国家的船舶工业、小至一个船舶企业能否在市场中生存和发展的关键.当造船业已经普遍意识到,以"信息化推动造船现代化"是中国造船工业追赶国际先进水平的最后机遇时,造船业的生存发展与IT厂商的策略几乎在同一时间不谋而合,在造船业竞争的搏奕中厂商的相助少不了.     

匈牙利农业机械化发展情况特点

匈牙利一向是一个重农国家,它位于欧洲中部的喀尔巴阡山盆地.全国地势低洼,北部为丘陵、南部为平原,气候适宜,耕地平坦.平原约占国土面积的60%,低丘陵地和山地约占40%.农业用地586万公顷,其中可耕地450万公顷,约占国土面积的48%.匈牙利种植的农作物主要有小麦、玉米和马铃薯等,主要出口以肉类和谷类为主的农产品.     

"认知"是信息化应用的绊脚石——访中国航天时代电子公司第十六研究所、七一七一厂信息处处长徐四海

此次航空航天信息化的大型选题报道让记者有幸来到地处关中平原,沃野千里,依山傍水,是与罗马并称为世界古都的"西安"进行一线采访.经过一夜的风雨洗礼,让西安这座古城尤显清新爽朗,仿佛这场风雨是特意为迎接我们而将这座城市冲刷地如此洁净,街道两旁郁郁葱葱的热带植物让你犹如置身南方小城一般.而我们此行的第一站便是位于西安市南郊航天城的中国航天时代电子公司第十六研究所、七一七一厂(以下简称7171厂).     

清理沼气废液废渣仅用五分钟

7月25日上午,江苏省农机具开发应用中心陈新华副主任、农业部南京农机化研究所陈永生主任等5人,来到江苏涟水县与农机局有关人员一起进行沼气清渣车清渣试验.研制成功的清渣车在小李集办事处胡楼村吴国成家中现场进行沼气池清渣,一池沼气废液废渣清理完毕,仅用5分钟,省时,省工,安全,效果很好.     

走区域应用示范与技术创新服务体系新模式

东营市位于黄河入海口,是黄河三角洲的中心城市,是在石油矿区基础上建设起来的新兴工业城市.近年来,除石油工业外,石油化工、盐化工、造纸、机电、轻纺、建材及生物医药等制造业门类得到较快发展,涌现出一批实力较强的企业集团,制造业逐步在东营市经济发展中占据了重要地位.     

2007年中国机床工具行业十大新闻

1.中央和地方省市主要领导频繁视察机床行业企业,国家为数控机床产业发展创造了空前良好的发展环境 胡锦涛、吴邦国、温家宝、贾庆林、李长春等党和国家领导人以及辽宁、黑龙江、山东、江苏、云南、湖北、广东、陕西、浙江、天津、重庆等省市主要领导相继视察了机床工具厂和数控系统厂.各级领导频繁视察,为数控机床产业的发展创造了空前良好的发展环境.     

基于VB和OpenGL的数控铣削仿真系统研究

介绍在Windows XP环境下,利用Visual Basic6.0和OpenGL开发的一个可视化的数控铣削仿真系统.该系统具有良好的界面和交互性,实现了数控加工轨迹的模拟仿真,并较好地完成了NC程序的正确性检查.     

Effects of prebuckling deformations on the elastic flexural-torsional buckling of laterally fixed arches

The effect of the prebuckling in-plane deformations on the elastic flexural-torsional buckling of laterally fixed circular arches is studied in this paper. The finite strains and the energy equation for the flexural-torsional buckling of arches have been derived based on an accurate orthogonal rotation matrix. A closed form solution for the elastic flexural-torsional buckling resistance of laterally fixed arches in uniform bending, including the effects of the prebuckling deformations, is obtained. It is found that the notion that the prebuckling deformations increase the flexural-torsional buckling moment of an arch or of a beam is not necessarily correct for a laterally fixed arch or beam in uniform bending, in deference to a laterally pinned arch. When a laterally fixed arch is subjected to positive uniform bending, the effects of the prebuckling deformations decrease the buckling moment, and the reduction of the buckling moment increases with an increase of the included angle and of the out-of-plane slenderness ratio of the arch. When a laterally fixed arch is subjected to negative uniform bending, the effects of the prebuckling deformations decrease the absolute value of its buckling moment when the included angle is very small, but increase the absolute value of the buckling moment when the included angle exceeds a certain value. The increase in the absolute value of the buckling moment increases with an increase of the included angle and of the out-of-plane slenderness ratio of the arch. When the ratio of the out-of-plane to the in-plane second moments of area of the cross-section is not small, both the reduction of the buckling moment of a laterally fixed arch in positive uniform bending and the increase of the buckling moment of a laterally fixed arch in negative uniform bending, are substantial.     

PHENOMENON OF CARVED DRIVING WHEELS

A newly found phenomenon of carved driving wheels of a rear-wheel-drive tractor used in an airport is discussed. The circum of every driving wheel is damaged at three regions,which distribute regularly and uniformly. Everyday,the tractor tows a trailer which are times heavier than the tractor,and moves on the same road in the airport. The phenomenon is explained by the torsional self-excited vibration system of the powertrain. The simplified torsional vibration system is discribed by a 2-order ordinary differential equation,which has a limit circle. Experiments and numerical simulations show the followings: Because of the heavy trailer,the slip ratio of the tractor’s driving wheels is very large. Therefore,there is severe torsional self-excited vibration in the tractor’s drivetrain,and the self-excited vibration results in severe and regular fluctuations of the rear wheel’s velocity. The severe fluctuations in velocity fastens the damage of the driving wheels. At the same time,the time interval in which an arbitrary point in the circum of the driving wheel contacts with the road twice is two times more than the period of the torsional self-excited vibration,and this times explained the existence of three damaged regions. At last,it points out that the phenomenon can be avoided when the torsional damping is large enough.     

DESIGN AND CAD SYSTEM OF THE FOOL FOR DRILL FLUTE

Based on the principles of differential geometry and kinematics, a mathematical model is developed to describe the grinding wheel axial cross-section with the radial cross-section of the flute in a given drill under the basic engagement condition between the generating flute and the generated grinding wheel (or disk milling tool). The mathematical model is good for the flute in the radial cross-section consisting of three arcs. Furthermore, a CAD system is also developed to represent the axial cross-section of the grinding wheel (or disk milling tool). With the system, the grinding wheel (or disk milling tool) axial cross-section that corresponds to the three-arc flute cross section can be conveniently simulated. Through the grinding experiment of drill flutes, the method and the CAD system are proved to be feasible and reasonable.     

孔隙阀式磁流变阻尼器准静力分析

建立了孔隙阀式磁流变阻尼器的轴对称模型.推导了孔隙阀内磁流变液压力梯度方程.对Herschel-Bulkley模型的磁流变阻尼器压力梯度进行了数值求解.应用代数方程理论,得到了Bingham模型的磁流变阻尼器压力梯度的解析解.最后,结合算例计算了孔隙阀内磁流变液的流速分布及阻尼器的阻尼力.     

车门静态强度的有限元分析模拟

轿车门系统结构设计与优化是整车开发过程中的重要环节。车门的强度直接关系到整车在冲击、碰撞等载荷下的安全问题,车门结构静态强度的计算分析,在车门结构设计进程中非常重要。文中首先简要介绍了静态强度所涉及到的非线性有限元的基本理论,然后以某中高级轿车前车门为例,利用计算机辅助分析车门的静态强度,考虑变形的非线性因素,通过对车门的非线性有限元求解来分析车门强度,由计算所得到的车门强度性能指标来指导车门的结构设计。     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.     

OPTIMIZING DESIGN OF MECHANICAL SELF-CENTERING DEVICE FOR SUSPENSION HEIGHT

Firstly, in view of the respective defects of existing self-centering devices for vehicle suspension height, the design scheme of the proposed mechanical self-centering device for suspension height is described. Taking the rear suspension of a certain light bus as a research example, the structures and parameters of the novel device are designed and ascertained. Then, the road excitation models, the performance evaluation indexes and the half-vehicle model are built, the simulation outputs of time and frequency domain are obtained with the road excitations of random and pulse by using MATLAB/Simulink software. So the main characteristics of the self-centering suspension are presented preliminarily. Finally, a multi-objective parameter design optimization model for the self-centering device is built by weighted sum approach, and optimal solution is obtained by adopting complex approach. The relevant choosing-type parameters for self-centering device components are deduced by using discrete variable optimal method, and the optimal results are verified and analyzed. So the performance potentials of the self-centering device are exerted fully in condition of ensuring overall suspension performances.     

平面应变颈缩扩展与剪切断裂的数值模拟

采用虚功率增率有限元法及Ｊ２形变理论，模拟韧性金属平面应变颈缩扩展，剪切断裂演化过程。运用载荷控制的自动识别方法以及各增量步间Ｅｕｌｅｒ控制方法，实现了均匀变形与非均匀变形临界状态的稳定过渡，采用本构方程的Ｅｕｌｅｒ显式积分，对Ｊ２形变理论塑性加载与弹性卸载的不连续性进行了改进，保证了变形局部化模拟过程的可靠性，最后，讨论了不同硬化指数及初始几何不均匀性对局部化力学行为的影响。     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.     

IMPROVED METHOD FOR HILBERT INSTANTANEOUS FREQUENCY ESTIMATION

In the mechanical fault detection and diagnosis field, it is more and more important to analyze the instantaneous frequency (IF) character of complex vibration signal. The improved IF estimation method is put forward aiming at the shortage of traditional Hilbert transform. It is based on Hilbert transform in wavelet domain. With the help of relationship between the real part and the imaginary part obtained from the complex coefficient of continuous wavelet transform or the analytical signal reconstructed in wavelet packet decomposition, the instantaneous phase function of the subcomponent is extracted. In order to improve the precise of IF estimated out, some means such as Linear regression, adaptive filtering, resampling are applied into the instantaneous phase obtained, then, the central differencing operator is used to get desired IF. Simulation results with synthetic and gearbox fault signals are included to illustrate the proposed method.