Photon-assisted Fano resonance and corresponding shot noise in a quantum dot

We have studied the Fano resonance in photon-assisted transport through a quantum dot. Both the coherent current and the spectral density of shot noise have been calculated. It is predicted that the shape of the Fano profile will also appear in satellite peaks. It is found that the variations of Fano profiles with the strengths of nonresonant transmissions are not synchronous in absorption and emission sidebands. The effect of interference on photon-assisted pumped current has also been investigated. We further predict the current and spectral density of shot noise as a periodic function of the phase, which exhibits an intrinsic property of resonant and nonresonant channels in the structures.

Computer-aided design of PV/wind hybrid system

A complete set of match calculation methods for optimum sizing of PV/wind hybrid system is presented. In this method, the more accurate and practical mathematic models for characterizing PV module, wind generator and battery are adopted; combining with hourly measured meteorologic data and load data, the performance of a PV/wind hybrid system is determined on a hourly basis; by fixing the capacity of wind generators, the whole year's LPSP (loss of power supply probability) values of PV/wind hybrid systems with different capacity of PV array and battery bank are calculated, then the trade-off curve between battery bank and PV array capacity is drawn for the given LPSP value; the optimum configuration which can meet the energy demand with the minimum cost can be found by drawing a tangent to the trade-off curve with the slope representing the relationship between cost of PV module and that of the battery. According to this match calculation method, a set of match calculation programs for optimum sizing of PV/wind hybrid systems have been developed. Applying these match calculation programs to an assumed PV/wind hybrid system to be installed at Waglan island of Hong Kong, the optimum configuration and its hourly, daily, monthly and yearly performances are given. (C) 2003 Elsevier Science Ltd. All rights reserved.

Dynamics of Multi-Stage Bladed Disks Systems

This paper presents a new and original method for dynamical analysis of multistage cyclic structures such as turbomachinery compressors or turbines. Each stage is modeled cyclically by its elementary sector and the interstage coupling is achieved through a cyclic recombination of the interface degrees of freedom. This method is quite simple to set up; it allows us to handle the finite element models of each stage's sector directly and, as in classical cyclic symmetry analysis, to study the nodal diameter problems separately. The method is first validated on a simple case study which shows good agreements with a complete 360 deg reference calculation. An industrial example involving two HP compressor stages is then presented. Then the forced response application is presented in which synchronous engine order type excitations are considered.

on string languages generated by spiking neural p systems

We continue the study of spiking neural P systems by considering these computing devices as binary string generators: the set of spike trains of halting computations of a given system constitutes the language generated by that system. Although the "direct" generative capacity of spiking neural P systems is rather restricted (some very simple languages cannot be generated in this framework), regular languages are inverse-morphic images of languages of finite spiking neural P systems, and recursively enumerable languages are projections of inverse-morphic images of languages generated by spiking neural P systems.

automatic construction of finite algebras

This paper deals withmodel generation for equational theories, i.e., automatically generating (finite) models of a given set of (logical) equations. Our method of finite model generation and a tool for automatic construction of finite algebras is described. Some examples are given to show the applications of our program. We argue that, the combination of model generators and theorem provers enables us to get a better understanding of logical theories. A brief comparison between our tool and other similar tools is also presented.

嵌入式DSP系统中SDF模型资源优化技术研究

随着嵌入式DSP系统硬件的飞速发展，各种数据和控制流被应用到嵌入式DSP应用程序的计算机辅助设计中去。其中同步数据流(SDF)被广泛用于图形化的DSP设计环境。同步数据流的特点在于能够在编译时刻静态地确定一个有效的调度序列，从而减少运行时的开销。而对于资源短缺的DSP系统，如何优化同步数据流编译生成程序的内存和计算资源具有重要的意义。 对于内存资源优化，研究热点计算体单一出现调度(SAS)算法对于存在反馈环和数据密集处理的应用不可解或内存优化效果很差。文中提出了将SAS和Non-SAS类型调度算法相结合的层次化的存储优化方法。该方法定义了数据密集分量和强连通分量来描述环和数据密集处理结构，并依据数据优先消耗原则设计了启发式的Non-SAS调度算法对分量进行存储优化。该方法适用于任意SDF模型，并有良好的存储优化效果。实验结果证实了其有效性。 计算资源优化即SDF模型的并行计算。本文针对简单SDF模型，提出一种基于优先权的多处理调度方法。它为程序模块分级，采用高优先级优先执行的策略实现了SDF图的多处理器并行静态调度。相对于其他方法，它不需要把SDF图转换为先序图，所以具有更好的时间与空间复杂度。实验结果证实了该方法的有效性。 针对计算体数目多，输入输出速率大的复杂SDF模型，一种基于通信的快速多水平优化方法被提出。它把SDF模型转化为基于通信的数据流模型，并应用快速多水平优化算法对其进行分区，最后把分区映射到原SDF模型中。通过分析，它有良好的时间和空间复杂度，并且优化后的并行程序有较短的程序执行时间和较高的吞吐率。 综上，本文为嵌入式SDF模型的资源优化提供了完善的优化方法。

围绕主题的同步交互学习支持方法的研究及工具开发

现代信息技术的发展促使世界各国进行教育信息化的改革。用IT技术辅助教学，特别是网络教学成为信息化教育的主要应用之一，它在提高教学效率的同时，缓解了知识爆炸对教育所带来的冲击，可是目前的IT技术只是用于加固传统落后的教学模式，不能从根本上改变现代教育不适应知识经济发展的社会需求，需要思考能建立适应信息社会人才需要的教育模式。 多尔的后现代课程观批判了现代主义课程观的弊端，例如封闭性、简单性和累积性，重视课程系统的开发性，课程内容的丰富性，注重学习环境的关联性。而网络教学突破教学时空的局限，提供丰富的教育资源，优化自主学习，强化教学互动。因此将后现代课程观理念融入网络教学的教学模式，用网络教学来支持后现代课程教学理念的实现，能为解决现代教学存在的问题开辟新的道路。 本文抓住后现代课程观的核心概念之一交互，通过分析目前网络教学中交互支持工具的现状，提出了围绕主题的同步交互学习支持的方法和工具实现，将后现代课程观中的交互理念与围绕主题学习的思想相结合，利用即时通信和个性化知识的再组织辅助学习中的交互过程，使得整个交互过程与学习内容紧密结合，提高了学习的效率和质量，体现了后现代课程观对课程教学的指导意义。

同步数据流模型调度序列的空间优化

提出了一种嵌入式DSP系统的存储优化方法。该方法基于同步数据流模型SDF(Synchronous Data Flow)。针对其他优化算法不适用于存在反馈环的同步数据流模型的问题,该方法为反馈环的空间优化设计实现了启发式的调度算法,并提出了将SAS(Single Appearance Schedules)和Non-SAS类型调度序列相结合的层次化的空间优化方案,为同步数据流模型调度序列的空间优化提供一个通用的解决方案。实验结果证实了该方案的有效性。

围绕主题的同步交互学习支持工具的设计与实现

提出了一种围绕主题的同步交互学习支持工具,该工具将后现代课程观中的交互理念与围绕主题学习的思想相结合,利用即时通信和个性化知识的再组织辅助学习中的交互过程,使得整个交互过程与学习内容紧密结合,有利于学习活动的深入开展,提高了学习的效率和质量,体现了后现代课程观对课程教学的指导意义。

CLIGEN非降水要素在黄土塬区的适用性评估

许多基于物理机制的水文和作物模型需要日序列气象数据来驱动,CLIGEN是为WEPP等模型产生气候输入文件的天气发生器,可以产生10个日序列气象变量来满足这种需要,但是其在中国的适用性需要进行评估。研究的目标是利用黄土高原陕西长武1957~2001年的气象数据评估CLIGEN产生非降水要素(最高温度、最低温度、露点温度、太阳辐射和风速)的能力。结果表明,CLIGEN对最高温度、最低温度和露点温度的模拟效果较好,对太阳辐射和极端气候事件的模拟效果较差,对风速的模拟效果最差。相关性检验表明CLIGEN很好地保持了气象要素的季节性,这对模拟农业生产是非常重要的;但是没有保留气象要素逐日的自相关和互相关性,进而导致产生的温度变化不符合连续渐变的规律。

围绕主题的同步交互学习支持方法的研究及工具实现

现代信息技术的发展促使世界各国进行教育信息化的改革。用IT技术辅助教学，特别是网络教学成为信息化教育的主要应用之一，它在提高教学效率的同时，缓解了知识爆炸对教育所带来的冲击，可是目前的IT技术只是用于加固传统落后的教学模式，不能从根本上改变现代教育不适应知识经济发展的社会需求，需要思考能建立适应信息社会人才需要的教育模式。 多尔的后现代课程观批判了现代主义课程观的弊端，例如封闭性、简单性和累积性，重视课程系统的开发性，课程内容的丰富性，注重学习环境的关联性。而网络教学突破教学时空的局限，提供丰富的教育资源，优化自主学习，强化教学互动。因此将后现代课程观理念融入网络教学的教学模式，用网络教学来支持后现代课程教学理念的实现，能为解决现代教学存在的问题开辟新的道路。 本文抓住后现代课程观的核心概念之一交互，通过分析目前网络教学中交互支持工具的现状，提出了围绕主题的同步交互学习支持的方法和工具实现，将后现代课程观中的交互理念与围绕主题学习的思想相结合，利用即时通信和个性化知识的再组织辅助学习中的交互过程，使得整个交互过程与学习内容紧密结合，提高了学习的效率和质量，体现了后现代课程观对课程教学的指导意义。

同步数据流可视化建模和调度优化的实现与研究

数据流是为解决数字信号处理领域应用程序设计、开发难度大等问题而提出的，和传统的控制流相比，数据流能够更加自然地描述信号处理系统，更加清晰地表达系统的并发性。应用数据流设计的信号处理系统具有较高的性能，采用数据流语言能够大大加速DSP应用程序的设计和开发。同步数据流（Synchronous Data Flow，简称SDF）基于数据流，它和数据流最大的不同在于：SDF的计算单元在编译时刻消耗数据和产生数据的数目固定，这一特点决定了采用SDF设计和建立的模型能够在编译时刻确定调度序列，使得SDF适合用于多速率信号处理系统的建模。模型化多处理器系统Modex是一个面向同步数据流的可视化建模系统，它支持开发人员运用SDF进行可视化建模、为建立的模型生成调度序列、对调度序列进行空间优化、为建立的模型生成面向目标平台的C语言代码、对模型仿真验证、对模型进行资源消耗评估、将模型映射到指定的处理器执行等。 本文介绍Modex系统的两个关键技术：可视化建模和SDF调度序列空间优化的实现和研究。文章着重介绍SDF模型描述语言的定义，图元的构建和组织，图元的图形显示，控制图元的控制器，直接操作图元的命令对象，图元和视图之间的同步机制以及图形编辑器等部分的设计和实现。Modex系统的可视化建模基于GEF(Graphical Editing Framework)，为同步数据流建模提供了丰富的可视化编辑操作，同时图元和视图之间松散耦合，可视化建模具有良好的互操作性以及扩展性。文章针对调度序列的空间优化提出了将SAS(Single Appearance Sequence）和非SAS类型调度序列相结合的思想，并基于该思想设计了生成空间优化的非SAS类型调度序列算法IAO（Increase Available Output），并结合EA(Evolutionary Approach)算法实现了面向通用,特别是存在反馈环的SDF模型的空间优化方案SGUTS（Solution for General Graph Using Two Kinds of Sequences）。SGUTS是一个层次化的优化框架，它通过聚集将一个存在反馈的模型分为上层模型和下层模型，然后采用EA、IAO算法分别为这两层模型进行优化，从而得到整个模型的优化结果。SGUTS不仅解决了存在反馈环的SDF模型空间优化问题，而且相比较其他算法，SGUTS取得了较好的优化结果。

Intense beam production of highly charged heavy ions by the superconducting electron cyclotron resonance ion source SECRAL (invited)

There has been increasing demand to provide higher beam intensity and high enough beam energy for heavy ion accelerator and some other applications, which has driven electron cyclotron resonance (ECR) ion source to produce higher charge state ions with higher beam intensity. One of development trends for highly charged ECR ion source is to build new generation ECR sources by utilization of superconducting magnet technology. SECRAL (superconducting ECR ion source with advanced design in Lanzhou) was successfully built to produce intense beams of highly charged ion for Heavy Ion Research Facility in Lanzhou (HIRFL). The ion source has been optimized to be operated at 28 GHz for its maximum performance. The superconducting magnet confinement configuration of the ion source consists of three axial solenoid coils and six sextupole coils with a cold iron structure as field booster and clamping. An innovative design of SECRAL is that the three axial solenoid coils are located inside of the sextupole bore in order to reduce the interaction forces between the sextupole coils and the solenoid coils. For 28 GHz operation, the magnet assembly can produce peak mirror fields on axis of 3.6 T at injection, 2.2 T at extraction, and a radial sextupole field of 2.0 T at plasma chamber wall. During the commissioning phase at 18 GHz with a stainless steel chamber, tests with various gases and some metals have been conducted with microwave power less than 3.5 kW by two 18 GHz rf generators. It demonstrates the performance is very promising. Some record ion beam intensities have been produced, for instance, 810 e mu A of O7+, 505 e mu A of Xe20+ 306 e mu A of Xe27+, and so on. The effect of the magnetic field configuration on the ion source performance has been studied experimentally. SECRAL has been put into operation to provide highly charged ion beams for HIRFL facility since May 2007.

Observation of charge-dependent azimuthal correlations and possible local strong parity violation in heavy-ion collisions

Parity (P)-odd domains, corresponding to nontrivial topological solutions of the QCD vacuum, might be created during relativistic heavy-ion collisions. These domains are predicted to lead to charge separation of quarks along the orbital momentum of the system created in noncentral collisions. To study this effect, we investigate a three-particle mixed-harmonics azimuthal correlator which is a P-even observable, but directly sensitive to the charge-separation effect. We report measurements of this observable using the STAR detector in Au + Au and Cu + Cu collisions at root s(NN) = 200 and 62 GeV. The results are presented as a function of collision centrality, particle separation in rapidity, and particle transverse momentum. A signal consistent with several of the theoretical expectations is detected in all four data sets. We compare our results to the predictions of existing event generators and discuss in detail possible contributions from other effects that are not related to P violation.