冲击载荷下的石油测试管柱减振系统的数值模拟

基于有限元分析软件ANSYS研究冲击载荷下石油测试管柱减振系统的动力学性质,在模拟过程中涉及几何非线性、材料非线性、状态非线性和动态加载等问题.建立新设计研制的减振器和以往现场用的减振器三维有限元模型,在ANSYS/LS-DYNA中进行仿真计算,讨论在冲击强度一定的条件下,三种不同频率范围内的半正弦脉冲力对减振效果的影响,并比较两种减振器的减振效果.并用实验结果验证模型.     

Using Adaptive Gain Scheduling LQR Method Control of Arm Driven Inverted Pendulum System Based on PIC18F4431

The arm driven inverted pendulum system is a highly nonlinear model, muhivariable and absolutely unstable dynamic system so it is very difficult to obtain exact mathematical model and balance the inverted pendulum with variable position of the ann. To solve this problem, this paper presents a mathematical model for arm driven inverted pendulum in mid-position configuration and an adaptive gain scheduling linear quadratic regulator control method for the stabilizing the inverted pendulum. The proposed controllers for arm driven inverted pendulum are simulated using MATLAB-SIMULINK and implemented on an experiment system using PIC 18F4431 mieroeontroller. The result of experiment system shows the control performance to be very good in a wide range stabilization of the arm position.     

The impact of combustion characteristics and flame structure on soot formation in oxy-enhanced and oxy-fuel diffusion flames

Based on a detailed chemical mechanism, impacts of combustion characteristics and flame structure on soot formation in opposed-flow diffusion ethylene flames was studied with different stoichiometric mixture fractions in O2/N2and O2/CO2atmospheres. The results showed the followings. 1) In both atmospheres, with the increase of stoichiometric mixture fraction, the flame structure changed significantly. The stagnation plane shifted toward the oxidizer side. Furthermore, there were less C2H2 but more O and OH to occur in the soot inception zone, therefore the amount of soot in the flame decreased. 2) Compared withN2, CO2had a suppression effect on soot formation, which was mainly due to thermal and direct chemical interaction effects of CO2. This is because the specific heat capacity of CO2is higher than that of N2, which will cause the flame temperature to drop,and mole fractions of C2H2, H, O, OH and main PAHs to decrease. Soot oxidation played a dominant role, while soot surface growth was attributed to the secondary position. Meanwhile, when CO2 abounded in the flame, OH concentration was increased through the backward reaction of CO+OH=CO2+H, and this would be conducive to the oxidation of soot precursor and incipient soot particles. In addition, the results of maximum particle density indicated the thermal effect of CO2on soot for-mation is more important than the direct chemical interaction effect.     

基于三角环的顶点着色问题解法

图的着色问题是一个NP难问题,本文着重探讨无向图的顶点的三色问题,提出了用构造三角环的极大独立集方法判断并尝试给出顶点三色问题的可行解,解决了顶点三色的可满足性问题,克服了以前图遍历过程中的回溯问题,以及由此推论顶点四色和五色问题的极大独立集。     

一种数控机床故障模拟装置的开发及应用

针对数控装置开发过程中测试工具欠缺的现状,以总线式数控装置为研究对象,分析了数控机床故障模拟的技术特点,提出了一种基于构建机床逻辑模型的故障模拟技术,开发了一套专用的故障模拟装置.并通过对华中数控HNC-08数控系统进行故障模拟实验验证.实验结果表明该装置满足数控装置测试故障自诊断功能的需求,有效的提高了测试效率及安全性.     

等值面的生成原理与算法

本文从工程实际中引出,由四变量离散数据图示等值曲面的问题,提出了构造等值曲面的四维画法几何生成方法,在用计算机实现此生成方法的过程中,从理论上证明了1982年Nguyen-Van-Phai提出的四面体网格化算法,这种算法的性质,即四面体球面过剩为最大的情况下是最佳的,可以有效地应用于计算机绘图和有限元分析的网格自动生成等方面。本文用此算法求出四变量离散数据的等值点,从而实现等值曲面的拟合。     

电力系统短期预报频率控制

随着火电厂的DCS系统和水电厂的计算机实时控制系统的广泛应用 ,如何发挥其优势以提高电力系统的稳定、可靠及高质量的运行 ,越来越引起人们的重视。本文对主调频水电站进行系统频率短期预报 ,并把预报结果直接应用于水电站的计算机频率控制。文中建立了频率调整的辨识模型、频率预报模型和主调频电站的有功出力控制模型 ,并分析了计算机仿真结果。     

Machining parts made from diverse materials by means of a composite tool

Russian Engineering Research -     

冰箱内胆模具底座的参数化建模设计

冰箱内胆模具底座属于非标准零件。基于UG NX 7.0软件设计了多副内胆底座模具,总结了非标准零件底座的建模参数,分析其中相互关联的尺寸参数,总结出了底座的特征参数。通过表达式功能,采用参数化设计方法,依据一个底座三维模型模板和相应的特征参数表达式数据文件,创建了具有拓扑结构的底座零件族。该方法可以自动、快速的设计出不同尺寸参数的底座三维,实现了模具底座的参数化建模,提高模具设计的工作效率,缩短了内胆模具产品的开发周期。     

粉料参数对罐形磁心开裂的影响

由于罐形磁心结构复杂,在其制作过程中,粉料参数以及在成型、烧结过程中都可能使罐形磁心产生裂纹,甚至形成开裂。本文分析了罐形磁心裂纹产生的原因,实验研究了粉料粒度分布和含水量对罐形磁心开裂的影响。实验获得了具有良好成型性和较高效率的粉体参数。