On a bifurcation governed by hysteresis nonlinearity

We consider autonomous systems with a nonlinear part depending on a parameter and study Hopf bifurcations at infinity. The nonlinear part consists of the nonlinear functional term and the Prandtl--Ishlinskii hysteresis term. The linear part of the system has a special form such that the close-loop system can be considered as a hysteresis perturbation of a quasilinear Hamiltonian system. The Hamiltonian system has a continuum of arbitrarily large cycles for each value of the parameter. We present sufficient conditions for the existence of bifurcation points for the non-Hamiltonian system with hysteresis. These bifurcation points are determined by simple characteristics of the hysteresis nonlinearity.     

CMS physics overview

The principal physics goals of the Compact Muon Solenoid experiment under construction at the Large Hadron Collider at CERN in Geneva are reviewed. Procedures to search for the Standard Model Higgs boson, supersymmetric Higgses and other supersymmetric particles are described.     

复合体系方法测量液体力学谱

本文介绍了采用复合体系，测量得到凝聚态物质从固态到液态连续变化力学谱的一种新的实验方法。以簧振动为例，给出了解析的计算公式，以及应用条件。通过进一步综合分析，得到具有更广应用范围的近似公式，可以近似应用于其他不同的振动模式，如低频扭摆。应用新的测量方法，给出了典型小分子玻璃材料甘油和碳酸丙稀从玻璃态到液态的力学谱，观察到甘油和碳酸丙稀玻璃化转变、碳酸丙稀的再结晶、熔化和挥发的过程；测量得到挥发过程中水的质量随时间精确变化的曲线。最后，本文给出了新方法的一些应用展望。     

电子束产生大尺度等离子体过程的数值模拟研究

建立了一个四组分一维混合模型，对电子束注入大气产生大尺度等离子体的过程进行了数值模拟.结果表明了能量为140keV、流强为50mA/cm²的注入电子束，可以产生线度为0.5m，密度为10¹²cm^-3量级的大气环境下等离子体.电子束所伴随的空间电荷效应由于等离子体的产生会很快消失，不影响后续的等离子体产生过程.电子束注入流强主要影响产生等离子体的密度，而电子束能量则同时影响其空间线度和密度. 关键词： 电子束 碰撞 电离     

Two modifications of the least cost per period heuristic for dynamic lot-sizing

This paper proposes two constructive heuristics for the well-known single-level uncapacitated dynamic lot-sizing problem. The proposed heuristics, called net least period cost (nLPC) and nLPC(i), are developed by modifying the average period cost concept from Silver and Meal's heuristic, commonly known as least period cost (LPC). An improved tie-breaking stopping rule and a locally optimal decision rule are proposed in the second heuristic to enhance performance. We test the effectiveness of the proposed heuristics by using 20 benchmarking test problems frequently used in the literature. Furthermore, we perform a large-scale simulation study involving three factors, 50 experimental conditions, and 100?000 randomly generated problems to evaluate the proposed heuristics against LPC and six other well-known constructive heuristics in the literature. The simulation results show that both nLPC and nLPC(i) produce average holding and setup costs lower than or equal to those of LPC in every one of the 50 experimental conditions. The proposed heuristics also outperform each of the six other heuristics evaluated in all experimental conditions, without an increase in computational requirements. Lastly, considering that both nLPC and nLPC(i) are fairly simple for practitioners to understand and that lot-sizing heuristics have been commonly used in practice, there should be a very good chance for practical applications of the proposed heuristics.     

光学低通滤波器的光学传递函数分析

光电成像系统的抽样过程会引起图像频谱在频谱空间上的多次复制,如果抽样过程不满足系统的奈奎斯特条件,相邻的频谱项就会产生混叠.光学传递函数可以反映系统中光学成像,抽样和重建等各个过程对图像信号频谱的响应.通过对使用光学低通滤波器(OLPF)光电成像系统的光学传递函数的分析,表明光学低通滤波器可以有效地限制图像的频谱宽度,使抽样满足奈奎斯特条件,达到消除频谱混叠,改善重建图像质量的目的.     

现代天文谱新篇——IAU投票界定太阳系行星

在2006年8月24日当地时间下午2点（北京时间晚9点30分）于捷克首都布拉格会议中心举行的国际天文学联合会IAU第26届代表大会上，来自不同国家的近500名正式代表，以举手表决的方式通过了执委会提出的关于太阳系行星定义的决议．该决议第一次明确提出了太阳系天体的分类规则：把太阳系中的行星和其他天体分为行星、矮行星、太阳系小天体三类；把矮行星中以冥王星为标志的海王外天体分为一个新的族。     

The application of a vehicle routing model to a waste-collection problem: two case studies

In this paper we suggest a unique model for estimating the operating cost of each of three waste-collection systems. Under the traditional system, which is widely used, waste is typically collected in plastic bags and a three-man crew is needed on each vehicle. The other two systems require a one-man crew for vehicle collecting street containers. The side-loader system with fixed body automatically empties street containers into the vehicle body and empties the load at the disposal site. The side-loader system with demountable body allows the separation of the waste collection phase from transport to the disposal site, since the vehicle body can be demounted. We also present two case studies and show how the estimation of operating costs is a critical issue in decisions regarding the type of system to be used for waste collection.