基于仿真技术的数控实验平台构建及应用

利用计算机图形学技术仿真数控加工系统,无论是在实验教学还是在生产培训上,都越来越受到重视。针对初次操作数控机床的学生培训事故率高、对机床刀具设备损坏大、教学培训效率低的状况,构建基于仿真技术的数控实验平台来进行数控教学和培训。介绍了数控仿真系统的应用原理、构建要素以及数控加工过程的动态图形仿真技术。结合零件加工实例阐述了数控仿真实验平台的运行过程。实例表明,数控仿真技术的应用,提高了学生的数控编程能力、数控机床操作能力以及数控系统的维护能力。

并联六坐标测量机的工作空间及其仿真研究

介绍了并联坐标测量机的特点 ,分析了影响并联坐标测量机工作空间的主要因素 ,推导出并联杆长度、运动副转角、并联杆干涉和结构限制等的约束条件。采用一维搜索方法确定了工作空间的边界并推导出其体积公式 ,明确了增大工作空间的途径是增大运动副转角和并联杆行程。

新一代分布式交互仿真支撑软件——RTI

首先介绍了基于HLA的建模与仿真技术框架 ,在此基础上对其支撑软件RTI的工作机制进行了深入的分析 ,给出了利用RTI建立成员的工作流程。最后结合代码介绍了用RTI开发联邦成员的一般过程。

基于Petri网的装配生产过程建模与仿真分析

针对一机电产品装配生产线,介绍了应用Flexsim仿真系统进行生产线建模与仿真的流程和步骤,研究讨论了建立生产线Petri网理论模型及Petri网模型转换为Flexsim仿真模型的方法。通过生产过程仿真结果分析,找到了影响该生产线生产率的瓶颈环节,并提出了生产线优化及改进方案。

控制系统数字仿真初探

计算机数字仿真技术应用在自动控制系统设计中所要解决的根本问题是依据离散系统的状态函数或传递函数求出系统输出响应。本文从重型机械CAD设计实际出发,将离散系统分成三种类型,并分别就三种类型进行了计算机数字仿真问题的分析研究。

DCS实现半直纺工序优化控制

叙述了聚酯增容改造中 ,利用DCS实现半直纺工序优化控制 ,解决了改造后稳产高产和设备安全运行的矛盾。

机器人关节间的碰撞检测

将多臂机器人各运动关节简化为具有一定直径的圆柱体 ,通过计算两圆柱体中心线间最短距离来进行机器人的碰撞检测研究。在此过程中 ,首先通过总结提炼两空间线段间的相互位置关系 ,在进行解析 ,推导的基础上 ,提出了 7个有意义的解析几何推论 ,直接可得出两空间线段间的最短距离 ,然后根据得出的结果 ,设计了一个机器人运动关节间的碰撞检测算法。该算法程序设计简单 ,计算量小 ,能有效地满足实际应用需要。

单相BOOST功率因数校正主电路模型的建立

由于单相BOOST功率因数校正电路具有结构简单、控制方便等特点得到了大量使用。建立了BOOST功率因数校正主电路的从控制到输出的传递函数 。

ENHANCED UNSTEADY AND NONLINEAR ROTOR WAKE MODEL FOR REAL-TIME FLIG HT SIMULATION

WT5 'BZThis paper presents an unsteady and nonlinear wake model based on th e widely used Peters He finite state dynamic wake model with improvements. The swirl component in the tip trace plane (TTP) can be predicted, nonlinear items are added into the linear theory, and the old small angle assumption use d in matrix prediction is removed. All of these enha ncements are aimed at the low speed flight phase and formulations for the induce d velocity field just in the TTP frame are derived. The corresponding FORTRAN pr ogram is tested and optimized for the real time applications on PCs.

ADAPTIVE NEURAL NETWORK ATTITUDE CONTROL FOR UNMANNED HELICOPTER

Adaptive flight control technology, feedback linearization, model inversion theory are reviewed and the error dynamic characteristics are analyzed, and an adaptive on-line neural network attitude control system is presented. The model inversion is under the hover condition. And the adaptive control law based on the neural network is designed to guarantee the boundedness of tracking error and control signals. Simulation results demonstrate that the nonlinear neural network augmented model inversion can self-adapt to the uncertainty and modeling errors of unmanned helicopters. Results are compared while the parameters of PD controller and robustness items are changed.

Simulation and experimental study on lubrication characteristics of vertical hydrostatic guide rails

In order to improve the cutting stiffness,the paper studies the vertical hydrostatic bearing in the slide when a ram is in feed process.The change of the oil film thickness on hydrostatic guide rail and the curve of the oil film thickness in various cutting forces are calculated and a relation model through theoretical analysis method is derived.The pressure field of the guide rail recess is simulated based on the finite volume method and demonstrated through experiments.The study is of vital theoretical significance for the improvement of machining accuracy of numerical control machines and the entire computer numerical control(CNC) equipment and provides valuable theoretical basis for the design of hydrostatic guide rail in engineering practice.

ANALYTIC STUDY ON POTENTIAL INSTABILITY AND SPIRAL STRUCTURE OF RAIN CLUSTERS

This paper presents a study on potential instability and spiral structure of unstable rain clusters.First,we develop a linearized non-axisymmetrical mathematic model for rain clusters in circular cylindrical coordinates and acquire its analytic solution.Second,we discuss the potential instability of non-axisymmetrical rain clusters.Finally,we conclude that spiral structures can exist in rain clusters.Our analysis indicates that potential instability occurs when humid stratification coefficient is less than zero.Unstable growth rate increases with the increase of the absolute value for humid stratification coefficient.The simpler the vertical structure of perturbation,the thicker the inversion layer;additionally,the smaller the radius of the rain clusters,the larger the unstable growth rate.Simulation results agree well with those from observation and forecast.The spiral structure simulated by our model is similar to a radar echo,suggesting that rain clusters with spiral structures can occur in the atmosphere.In addition,they are generally close to the model solution in this work.

Numerical Simulation and Control of Two-Phase Flow with Evaporation in a Vertical Tube Submitted to a Conjugate Heat Transfer

A better understanding of two-phase flows with evaporation allows leading to an optimal design of evaporators. For that purpose, numerical simulations are very useful. In this paper, a numerical study has been carried out in order to model and simulate the combination of a two-phase flow with evaporation in a vertical tube. The VOF （volume-of-fluid） multiphase flow method and a phase-change model for the mass transfer have been used. For an accurate modeling, the effect of axial conduction has been also taken into account using a conjugate heat transfer model. Since thermal oscillations are undesirable as they can lead to the failure of the tube, flow instabilities have also been analyzed, using FFT （fast Fourier transforms）, in order to comprehend their behavior and influence. A control study of the flow instabilities in the tube is also presented. For that purpose tube inlet temperature has been varied using a gain control parameter.

Design and Simulation of a Passive Vertical Suspension System for Spray Boom Structure

The most usual way of using chemical method to protect crop against weed, insects, and fungi is spraying the mixture of chemicals and water onto crop through the nozzles. Sprayers usually moved on the field by tractor, and tractor induced unwanted vibration to sprayer because of uneven soil or terrain. This oscillation leads to over-doses and under-doses of chemical sprayed on the field. For this reason, many commercial and some theoretical suspension were made to reduce undesirable vibration. Therefore, in this study a finite element based model was established to represent the dynamic behavior of spray boom structure with 8m width. The first tenth natural frequencies were obtained between 9.25 Hz to 1,182.5 Hz. Also, a passive vertical suspension was designed to remove unwanted vibration with 0.5 vibration transmissibility. Finally, the suspension system was simulated to be as certain of its efficiency. The results of simulation have good agreement to the proposed aim.

The Design and Simulation Analysis of Adjustable DC Source Circuit based on AD 13 Software

DC regulated power has play a decisive role status in the modem enterprise production and family life. With the development of science and technology, all kinds of computer simulation technology is increasingly rising, the paper simulate and compare common DC regulated power with adjustable DC regulated power by Altium Designer software, intuitively demonstrates the stabilizing effect of the circuit, and introduces the characteristics of adjustable DC regulated power. Using AD13 software simulate and design DC stabilized power supply circuit, calculated the main parameters of the circuit, simulated and analyzed the circuit working simulation process and the working state of the circuit, it can visually verify the results of the theoretical analysis, and get relevant conclusions.

Remarks on the Number of Rational Points on a Class of Hypersurfaces over Finite Fields

Let Fq be the finite field of q elements and f be a nonzero polynomial over Fq. For each b ∈ Fq, let Nq（f = b） denote the number of Fq-rational points on the affine hypersurface f = b. We obtain the formula of Nq（f= b） for a class of hypersurfaces over Fq by using the greatest invariant factors of degree matrices under certain cases, which generalizes the previously known results. We also give another simple direct proof to the known results.

Mathematical Simulation of Lithium Bromide Solution Laminar Falling Film Evaporation in Vertical Tube

For utilization of the residual heat of flue gas to drive the absorption chillers,a lithium-bromide falling film in vertical tube type generator is presented.A mathematical model was developed to simulate the heat and mass coupled problem of laminar falling film evaporation in vertical tube.In the model,the factor of mass transfer was taken into account in heat transfer performance calculation.The temperature and concentration fields were calculated.Some tests were conducted for the factors such as Re number,heating flux,the inlet concentration and operating pressure which can affect the heat and mass transfer performance in laminar falling film evaporation.The heat transfer performance is enhanced with the increasing of heat flux.An increasing inlet concentration can weaken the heat transfer performance.The operating pressure hardly affects on heat and mass transfer.The bigger inlet Re number means weaker heat transfer effects and stronger mass transfer.The mass transfer obviously restrains the heat transfer in the falling film solution.The relation between dimensionless heat transfer coefficient and the inlet Re number is obtained.

Affine-periodic solutions by averaging methods

This paper concerns the existence of affine-periodic solutions for perturbed affine-periodic systems.This kind of affine-periodic solutions has the form of x(t+T)≡Qx(t) with some nonsingular matrix Q,which may be quasi-periodic when Q is an orthogonal matrix. It can be even unbounded but x(t)/|x(t)| is quasi-periodic,like a helical line. for example x(t)=e^(at)(cos ωt, sin ωt), when Q is not an orthogonal matrix. The averaging method of higher order for finding affine-periodic solutions is given by topological degree.