NEW METHODS FOR CALCULATING ACTIVITIES OF COMPONENTS FROM PHASE DIAGRAMS IN BINARY PERITECTIC SYSTEMS

ＮＥＷＭＥＴＨＯＤＳＦＯＲＣＡＬＣＵＬＡＴＩＮＧＡＣＴＩＶＩＴＩＥＳＯＦＣＯＭＰＯＮＥＮＴＳＦＲＯＭＰＨＡＳＥＤＩＡＧＲＡＭＳＩＮＢＩＮＡＲＹＰＥＲＩＴＥＣＴＩＣＳＹＳＴＥＭＳ①ＺｈａｎｇＹｏｎｇｊｕｎＨｕｎａｎＳｕｐｅｒｉｏｒＴｅｃｈＭａｔｅｒｉ...     

基于单神经元自适应PID控制的位置扰动型电液伺服施力系统

针对位置扰动型电液伺服施力系统中多余力矩和参数变化问题，在用结构不变性原理进行补偿的基础上，采用单神经元自适应PID控制来确保系统有满意的跟踪性能。采用这种控制方法，可以较好地消除位置干扰的影响，同时克服系统的非线性及参数时变等因素的影响，提高了系统的鲁棒性和跟踪性能。仿真结果验证了上述结论。     

Isothermal section at 1673 K of the Mo–Ru–Si diagram and crystallographic structures of ternary phases

Efforts to improve the high temperature behavior of MoSi₂ in oxidizing environments led to the investigation of the Mo–Ru–Si phase diagram. The isothermal section at 1673 K was determined by X-ray diffraction, optical and scanning electron microscopies and EPMA. Five new silicides were identified and their crystallographic structure was characterized using conventional and synchrotron X-ray as well as neutron powder diffraction. Mo₁₅Ru₃₅Si₅₀, denoted α-phase, is of FeSi-type structure, space group P2₁3, a=4.7535 (5) Å, D_x=7.90 g. cm⁻³, Bragg R=7.13. Mo₆₀Ru₃₀Si₁₀ is the ordered extension of the Mo₇₀Ru₃₀ σ-phase with space group P4₂/mnm, a=9.45940(8) Å, c=4.94273(5) Å, D_x=6.14 g. cm⁻³, Bragg R=5.75.     

NiAl表面能的分子动力学计算

利用嵌入原子类型的势函数，通过分子动力学方法计算了Ｂ２结构标准化计量比ＮｉＡｌ合金的四个低指数晶面在６种温度时的表面能。计算结果表明，表面能随温度的升高呈增加趋势；最密排面的表面能最低；一些表面在高温下发生了重构或成分偏析等表面反应，用类似方法计算了ｆｃｃ结构Ｎｉ的表面能，计算结果与已知实验研究基本一致。     

光纤通信技术在渠道长距供水信息系统中的设计与应用

长距离供水渠道地处偏远,点多线长,采用信息化技术手段进行远程集中控制成为必然,光纤通信技术作为远控的基础显得尤为重要。文章介绍了南干渠供水信息系统中建设光纤通信系统的必要性和重要性,以及光纤通信系统结构、系统链路和系统设备选型,以达到无人值班、少人值守、集中控制的设计目标。     

Global robust output tracking control for a class of cascade nonlinear systems with unknown control directions

We investigate the global robust tracking problem via output feedback for a class of cascade nonlinear systems with dynamic uncertainties and non-vanishing disturbances. It does not require a priori knowledge of the sign of the high-frequency gain. A recursive design scheme is presented using the ideas of pseudosign function, Nussbaum-type gain technique and the deadzone method. It is shown that under some conditions, the tracking error can be guaranteed asymptotic to the interval [?ε, ε]?? with arbitrary prescribed ε>0 after a finite time, while keeping all signals of the resulting closed-loop systems bounded. The simulation results demonstrate the effectiveness of the proposed algorithm.     

Continuous-time orbit problems are decidable in polynomial-time

We place the continuous-time orbit problem in P$\mathsf{P}$, sharpening the decidability result shown by Hainry [7].     

Implementation and performance evaluation of a scheduling algorithm for divisible load parallel applications in a cloud computing environment

Cloud computing is an emerging technology in which information technology resources are virtualized to users in a set of computing resources on a pay‐per‐use basis. It is seen as an effective infrastructure for high performance applications. Divisible load applications occur in many scientific and engineering applications. However, dividing an application and deploying it in a cloud computing environment face challenges to obtain an optimal performance due to the overheads introduced by the cloud virtualization and the supporting cloud middleware. Therefore, we provide results of series of extensive experiments in scheduling divisible load application in a Cloud environment to decrease the overall application execution time considering the cloud networking and computing capacities presented to the application's user. We experiment with real applications within the Amazon cloud computing environment. Our extensive experiments analyze the reasons of the discrepancies between a theoretical model and the reality and propose adequate solutions. These discrepancies are due to three factors: the network behavior, the application behavior and the cloud computing virtualization. Our results show that applying the algorithm result in a maximum ratio of 1.41 of the measured normalized makespan versus the ideal makespan for application in which the communication to computation ratio is big. They show that the algorithm is effective for those applications in a heterogeneous setting reaching a ratio of 1.28 for large data sets. For application following the ensemble clustering model in which the computation to communication ratio is big and variable, we obtained a maximum ratio of 4.7 for large data set and a ratio of 2.11 for small data set. Applying the algorithm also results in an important speedup. These results are revealing for the type of applications we consider under experiments. The experiments also reveal the impact of the choice of the platforms provided by Amazon on the performance of the applications under study. Considering the emergence of cloud computing for high performance applications, the results in this paper can be widely adopted by cloud computing developers. Copyright © 2014 John Wiley & Sons, Ltd.