河津电厂2×350MW机组锅炉调试综述

介绍了河津电厂进口机组锅炉设备的设计特点及调试过程 ,分析了调试阶段遇到的主要问题 ,提出了此类大型电站锅炉设计选型和调试的参考意见     

机械原理课程设计中的计算机辅助设计

本文阐述了机械原理课程设计教学改革的必要性、可行性、存在的一些问题及解决方法、机械原理课程设计的发展方向及展望。     

基于PSD系列芯片的单片机电路设计

简要介绍了如何使用ＰＳＤ芯片来构成单片机系统的硬件电路。     

Gain Scheduled Output Feedback Control Based on LTI Controller Interpolation that Preserves LPV H ∞ Performance

A new approach to the design of a gain scheduled output feedback controller based on linear time-invariant (LTI) controller interpolation that preserves H performance without a varying-parameter rate feedback is proposed. After the controller design is translated into parameterized linear matrix inequalities about parameter matrices based on a parameter-dependent Lyapunov function, the sufficient condition is given for the partition of the varying-parameter set based on the concept of H performance covering. The varying-parameter set is thus partitioned into sufficiently small subsets. After the constant matrices are found for each of the subsets, the required continuous parameter matrices are obtained by using interpolation. The proposed controller overcomes the drawback that the gain scheduled controller may not be found by using the existing gain scheduled linear parameter varying (LPV) controller synthesis. Moreover, the varying-parameter rate feedback is eliminated and the conservatism of the controller design is reduced by means of limiting the upper bound of the varying-parameter rate. Simulation and experiment results prove the effectiveness of the proposed controller.     

直齿锥齿轮参数化三维建模方法

介绍了在AutoCAD 环境下,用Autolisp 语言编程在计算机上实现直齿锥齿轮参数化三维建模的方法.程序设计是基于齿轮范成法切齿原理.使用该研究成果,只需加载Autolisp程序,输入模数、齿数、齿轮分度圆锥角等参数,便可以自动生成刀具和轮坯,齿轮的轮齿由刀具与轮坯间的相对滚切而形成.程序中还设计了轴、孔及键槽等结构,最后生成按指定参数的标准直齿锥齿轮模型.     

Research on Stress and Strength of High Strength Reinforced Concrete Drilling Shaft Lining in Thick Top Soils

High strength reinforced concrete drilling shaft linings have been adopted to solve the difficult problem of supporting coal drilling shafts penetrating through thick top soils. Through model experiments the stress and strength of such shaft linings are studied. The test results indicate that the load beating capacity of the shaft lining is very high and that the main factors affecting the load bearing capacity are the concrete strength, the ratio of lining thickness to inner radius and the reinforcement ratio. Based on the limit equilibrium conditions and the strength theory of concrete under multi-axial compressive stressed state, a formula for calculating the load-beating capacity of a high strength reinforced concrete shaft lining was obtained. Because the concrete in a shaft lining is in a multi-axial compressive stress state the compressive strength increases to a great extent compared to uni-axial loading. Based on experiment a formula for the gain factor in compressive strength was obtained： it can be used in the structural design of the shaft lining. These results have provided a basis for sound engineering practice when designing this kind of shaft lining structure.     

基于MapObjects的电子地图信息系统的设计与实现

利用MapObjects2.3在Visual C 6.0环境下开发是GIS开发的主要途径,介绍用MapObjects2.3在Visual C 6.0环境下开发的电子地图系统及其实现方法.     

ℋ︁∞ and l2–l∞ filtering for two‐dimensional linear parameter‐varying systems

In this paper, the ??_∞ and l₂–l_∞ filtering problem is investigated for two‐dimensional (2‐D) discrete‐time linear parameter‐varying (LPV) systems. Based on the well‐known Fornasini–Marchesini local state‐space (FMLSS) model, the mathematical model of 2‐D systems under consideration is established by incorporating the parameter‐varying phenomenon. The purpose of the problem addressed is to design full‐order ??_∞ and l₂–l_∞ filters such that the filtering error dynamics is asymptotic stable and the prescribed noise attenuation levels in ??_∞ and l₂–l_∞ senses can be achieved, respectively. Sufficient conditions are derived for existence of such filters in terms of parameterized linear matrix inequalities (PLMIs), and the corresponding filter synthesis problem is then transformed into a convex optimization problem that can be efficiently solved by using standard software packages. A simulation example is exploited to demonstrate the usefulness and effectiveness of the proposed design method. Copyright © 2007 John Wiley & Sons, Ltd.     

Parameterized complexity of basic decision problems for tree automata

There are many decision problems in automata theory (including membership, emptiness, inclusion and universality problems) that are NP-hard for some classes of tree automata (TA). The study of their parameterized complexity allows us to find new bounds of their nonpolynomial time algorithmic behaviours. We present results of such a study for classical TA, rigid tree automata, TA with global equality and disequality and t-DAG automata. As parameters we consider the number of states, the cardinality of the signature, the size of the term or the t-dag and the size of the automaton.     

浅谈农村低压电网规划设计中应注意的几个问题

农村低压网络往往受当地气候、地形、用电负荷等条件的影响,勘测和规划设计比较复杂,这就要求勘测设计人员要全方位多领域广角度的进行勘测分析.本文对农村低压网络规划设计中需注意的几个问题进行了阐述,为更规范、合理地进行农村配电网规划和设计提出了建议.