改进异步电机直接转矩控制系统的仿真研究

本文介绍了直接转矩控制系统的控制原理,并针对基于直接转矩控制的异步电动机运行时存在较大的电流及转矩脉动问题,提出一种新的控制方案,并基于Matlab 6.5对这种新方法进行仿真,仿真结果表明该方案能有效的解决电流及转矩脉动的问题.     

一种新的基于直觉模糊集的作战决策算法

针对现有作战决策算法存在的不足,提出了一种新的基于直觉模糊集的作战决策算法.用直觉模糊值表示可行方案指标的不确定信息,综合考虑了方案满足指标的可能性、不满足的可能性和未知的可能性3个方面的因素,给出了直觉模糊决策矩阵的建立方法和可行方案优劣度排序方法.实例及实际应用证明了算法的有效性与可行性.     

Strengthening of Preloaded RC Beams Using Hybrid Carbon Sheets

Reinforced concrete (RC) beams subject to service loads of 40 or 60% of steel yielding were strengthened using hybrid continuous carbon fiber sheets. The hybrid systems were made of high-strength and high-modulus carbon sheets, and compared with systems using only high-strength carbon. It was found that the use of high-modulus carbon sheets in hybrid systems could increase the yielding load, the flexural stiffness, the postyielding ductility, and reduce the crack opening in concrete. The slope changes on load-deflection curves at steel yielding are not noticeable in hybrid systems. The tensile strains developed in hybrid sheets after the fracture of high-modulus carbon are higher in magnitude and distributed in a larger area, leading to an ultimate carbon fracture with concrete crushing. These unique features are attributed to the high stiffness and low ultimate tensile strain of the high-modulus carbon fibers which stiffen the structures, avoid or delay the fiber-reinforced polymer debonding, and facilitate the deformability during their subsequent breakdown.     

一种复合型数值方法的改进与算法实现

文中对原有的复合方法进行了改进,提出了一种新的复合型数值方法,这种方法解决了原方法求解含源项的问题时存在数值震荡的缺点。为了验证算法的有效性,对计算流体力学中一阶浅水波问题的两个典型的算例进行了数值模拟,在解的光滑性、锐利性等几个方面做了分析,结果表明改进后的方法既消除了数值震荡现象,又能准确地逼近真解,求出锐利的间断,是一种行之有效的数值方法。     

论BFe30—1—1冷凝管生产工艺及其改进的途径

论述了ＢＥｅ３０－１－１冷凝管生产工艺的优点及主要问题，对现行工艺提出了改进方案。     

热分层流动计算中若干差分格式的比较

本文应用常规的守恒方程及湍流模型，对二维池内热分层流动建立了数学模型，并在Ｐａｔａｎｋａｒ的压力校正法基础上对该数学模型进行了数值计算，计算中的差分格式为乘方格式、一阶迎风、二阶迎风和ＱＵＩＣＫ。通过与实验的比较分析，建议计算应采用ＱＵＩＣＫ格式，并在进行风格独立性试验的基础上使用加密网络。     

压电超声微电机混合结构定子的固有频率特性分析

压电超声微电机是依靠定子振动变换能的功率器件，定子性能将直接关系到微电机能否实现，本文采用Ｒａｙｌｅｉｇｈ－Ｒｉｔｚ方法来分析机械中经常采用的多层膜结构（混合结构）定子的固有振动特性，推导中考虑了平面应力和弯曲应力对固有频率的影响，模拟计算和实验结果符合得较好，此外还讨论了定子有关参数对固有频率的影响。     

NUMERICAL MODEL FOR DYNAMIC SIMULATION OF TRAFFIC FLOW

ＮＵＭＥＲＩＣＡＬＭＯＤＥＬＦＯＲＤＹＮＡＭＩＣＳＩＭＵＬＡＴＩＯＮＯＦＴＲＡＦＦＩＣＦＬＯＷＷｕＺｈｅｎｇ；ＺｅｎｇＬｉ－ｎｏｎｇ（ＤｅｐａｒｔｍｅｎｔＡｐｐｌｉｅｄＭｅｃｈａｎｉｃｓ，ＦｕｄａｎＵｎｉｖｅｒｓｉｔｙ，Ｓｈａｇｈａｉ２００４３３，Ｐ...     

河道溃堤与溃堤波的一、二维耦合计算数值模拟

建立了一维河道溃堤与二维溃堤波耦合计算的水力模型、其中，河道的计算采用一维明渠非恒定流Saint—Venant方程组，求解的过程与溃口的数值模拟耦合；溃堤按渐溃计算，将溃口模拟为梯形，随时间线性增大；溃堤波的计算采用在有限体积无结构网格上建立的TVD—MUSCL格式．模拟算例表明，建立的河道溃堤与溃堤波的一、二维耦合计算水力模型模拟结果比较接近真实溃堤过程．     

Advances in cryptography and information security—introduction of 2002–2006 progress of SKLOIS

This paper introduces the research progress of the State Key Laboratory of Information Security (SKLOIS) in China during 2002–2006. This introduction covers four selected areas with each covering some selected research findings. The four selected areas are: the fundamentals of cryptography; the design, analysis and testing of block cipher algorithms; the design and analysis of security protocols based on computational intractability; authentication, authorization and their applications.