大气中二氧化碳污染与气候演化关系的胞映射计算研究

改进了简单胞映射算法,应用于具有外源强迫特性的Saltzman气候模式——能量平衡气候模式的计算分析,从而有效、动态和直观地揭示大气环境中海温、海冰冰界和二氧化碳浓度之间非线性耦合的相互作用及其整个大气系统的复杂演化过程,得到了在给定控制参数下胞映射吸引子和各步吸引域在胞映射相空间中的分布图形,刻划了系统长期演化的全局性态。另外,通过调试A参数还发现它对系统准稳态演化过程的影响敏感,参数A值过于简化可能导致系统信息丢失。     

胞映射方法研究三峡库区流域富营养化污染的演化性态

用胞映射方法对两种流域富营养化污染非线性简化系统的演化过程和全局性态进行了数值仿真、分析和探讨，结果表明：胞映射方法在解决流域时空混沌问题时表现出良好的解析能力，可从复杂动力学系统中提取常规方法无法获取的混沌形态、演化模式、奇异吸引域和吸引子特征，有助于深层次上认识和揭示复杂水域富营养化污染体系的演变过程和产生混沌的原因，为三峡库区富营养化污染的趋势预报和调控机制的研究提供新思路和实现技术。     

应用胞映射算法研究非线性化学模拟系统

用简单胞映射和广义胞映射法程序对若干非线性化学动力学模拟系统的演化过程，内在机制和全局性态进行了数值计算和分析。结果表明：胞映射方法在普适性和定量性方面表现出很好的解析功能，能够从复杂动力学系统中提取其他方法无法获取的分形结构，化学混沌，演化模式和稳定性特征，从而有助于揭示复杂非线性化学体系深层次的内在规律和机制。     

胞映射基本理论与算法实现

胞映射方法是求解非线性复杂系统全局性态的一种数值计算技术,结合多线程并行处理的可视化技术,能够地对非线性化学动力学体系的复杂演化过程、奇异吸引域和混沌性态等进行有效、动态和准确地解析从而深刻揭示系统的内在机制。结合编程实践详细介绍ＨｓｕＣ．Ｓ创立的胞映射理论（包括简单胞映射和广义胞映射）的基本概念、算法实现框图、编程模块和应用技巧。讨论分析了胞映射方法的优势,结果表明：胞映射理论具有普遍适应性和求     

胞映射技术研究非线性化学系统的性态

用胞映射方法对典型的非线性化学动力学系统,例如对著名的ＢＺ振荡反应、ＷＲ反应和Ｒｏｓｓｌｅｒ反应等复杂的非线性化学动力学体系的演化过程、内在机制、吸引环和振荡行为进行了数值仿真和分析,结果表明：胞映射方法能够揭示常规方法无法获取的内在规律和表象,进一步显示了胞映射方法普适性、定量性和求解性。     

C/S分布式并行处理技术在高速局域网平台上实现非线性环境化学胞映射体系的大规模计算

通过100Mb/S集线器连接4台双CPU和2台单CPU计算机构成分布式并行计算的局域网平台，采用VC＋＋6．0高效、稳定、方便和成功地实现了分布式多线程并行计算，将非线性环境化学问题的胞映射大规模计算数值解体系进行了有效划分，并合理地分配到局域网上的每一台计算机上的每一个CPU中，然后通过局域网返回各自的处理结果，最后在客户机上完成各单项任务的总装，达到了可持续利用现有计算机资源和大幅度提高计算效率的目的。用这种低成本方式简单、清晰和快捷地掌握并行处理技术十分适应非计算机专业科研人员用来解决超大负荷计算量的复杂问题。     

基于元胞遗传机制的虚拟网络映射算法

满足节点和链路约束条件的虚拟网络请求最优映射问题是NP-难问题,粒子群算法和遗传算法等启发式算法是解决这类问题的主要手段。这类启发式算法从数学模型优化的角度来求解问题,但未考虑虚拟网络映射节点本身的变化对最优解的影响,存在收敛速度较慢和容易陷入局部最优解的问题。文中将元胞遗传机制引入虚拟网络映射问题中,提出了虚拟网络映射算法VNE-CGA。该算法利用元胞自动机对节点建模,使用“B4567/S1234”规则来替代传统遗传算法中的交叉操作;通过对邻居的学习来指导个体的寻优过程,弥补了传统遗传算法的固有缺陷,最终提高了虚拟网络请求的接受率以及底层物理网络的运营收益。     

二维Logistic映射中混沌与分形的研究

研究了二维Ｌｏｇｉｓｔｉｃ映射非线性动态行为的普适特征后发现,控制参数不同,二维Ｌｏｇｉｓｔｉｃ映射可分别按Ｆｅｉｇｅｎｂａｕｍ途径、Ｒｕｂｅｌｌｅ－Ｔａｋｅｎｓ－Ｎｅｗｈｏｕｓｅ方案和Ｐｏｍｅａｕ－Ｍａｎｎｅｖｉｌｌｅ途径走向混沌,且在控制参数空间中的较大区域,其通向混沌的道路与Ｈｏｐｆ分岔有关,在这些途径上可观察到锁相和准周期运动。同时对二维Ｌｏｇｉｓｔｉｃ映射的分形研究表明,控制参数不同,分     

计算网格中独立任务批模式调度映射算法研究

本文研究了计算网格中支持独立任务的批模式调度映射算法,详细介绍了极小极小算法(Min-Min)、极大极小算法(Max-Min)、最大时间跨度算法(Max-Int)三种典型的映射算法的算法原理,并结合一个具体的应用实例分析比较了三种算法的性能参数。最后针对三种映射算法的特点提出了自己的见解。     

基于映射关系的云模型控制器研究

首先介绍了云模型的基本概念和规则推理,分析了云模型的线性映射关系和非线性映射关系,然后设计出基于多种映射关系的不同云模型智能控制器。最后与常规PID控制系统进行了对比,仿真结果表明了本文设计方法的有效性。     

基于胞参考点映射法对转子/定子碰摩响应的全局分析

利用胞参考点映射法对两自由度(四维)分段光滑的转子/定子碰摩模型的全局响应特性进行了计算,着重对解析分析得到的碰摩系统典型的吸引子共存现象进行了验证,确定了相应吸引子的吸引域.此外,通过计算转子/定子碰摩系统全局特性随系统参数变化的演化特点,考察了吸引子与其吸引域边界对参数变化的敏感性,讨论了其对实际转子/定子碰摩系统...     

CO detection in H2 reducing atmosphere with mini fuel cell

A prototype of a miniaturized fuel cell has been studied in order to detect carbon monoxide in hydrogen-rich atmosphere for PEMFC (proton exchange membrane fuel cell) applications. It consists on a single PEMFC (membrane-electrode-assembly supplied by CEA/LITEN) directly fed by the hydrogen-carbon monoxide mixture while the cathode is exposed to ambient air. Experiments have been carried out on a laboratory testing bench with simulated reforming gas. Two working modes have been studied. For low CO concentrations (≤20 ppm), the amperometric mode is suitable but a regeneration in air is necessary to obtain a good reversibility of the sensor response. On the contrary, for higher CO concentrations (250-4000 ppm), a good reversible response is observed without air regenerating by using a potentiometric or quasi-potentiometric mode. Therefore, this prototype of mini fuel cell sensor seems to be convenient for monitoring reformed gases either for low temperature PEMFC which are poisoned by very low traces of CO or for high temperature PEMFC which can operate at higher CO concentrations.     

Multi‐objective optimal motion control of a laboratory helicopter based on parallel simple cell mapping method

This paper presents a study of multi‐objective optimal design of nonlinear control systems and has validated the control design with a twin rotor model helicopter. The gains of the porportional integral differential (PID) control are designed in the framework of multi‐objective opitmization. Eight design paramaters are optimized to minimize six time‐domain objective objective functions. The study of multi‐objective optimal design of feedback control with such a number of design paramaters and objective functions is rare in the literature. The Pareto optimal solutions are obtained by the proposed parallel simple cell mapping method consisting of a robust Pareto set recovery algorithm and a rolling subdivision technique. The proposed parallel simple cell mapping algorithm has two features: the number of cells in the invariant set grows linearly with the rolling subdivisions, and the Pareto set is insensitive to the inital set of seed cells. The current control design is compared with the classical LQE control for linear systems, and is also experimentally validated. The current design provides improved control performance as compares with the LQR control, and is applicable to complex nonlinear systems.     

SimplyRep: A simple and effective reputation system to fight pollution in P2P live streaming

Peer-to-Peer (P2P) streaming has become a popular platform for transmitting live content. However, due to their increasing popularity, P2P live streaming systems may be the target of user opportunistic actions and malicious attacks, which may greatly reduce streaming rate or even stop it completely. In this article, we focus on a specific type of attack called content pollution, in which malicious peers tamper or forge media data, introducing fake content before uploading it to their partners in the overlay network. Specifically, we present a new decentralized reputation system, named SimplyRep, that quickly identifies and penalizes content polluters, while incurring in low overhead in terms of bandwidth consumption. We evaluate our method with both simulation and experiments in PlanetLab, comparing it against two previously proposed approaches, namely, a centralized black list and a distributed reputation system, in various scenarios. Our results indicate that SimplyRep greatly outperforms the two alternatives considered. In particular, both black list and the distributed reputation method perform poorly when polluters act jointly in a collusion attack, reaching a data retransmission overhead (triggered by polluted chunks received) of 70% and 30%, respectively, whereas the overhead experienced by SimplyRep is at most 2%. Our results also show that SimplyRep is able to quickly isolate almost all polluters under a dissimulation attack, being also somewhat robust to a whitewashing attack, although the latter remains a challenge to effective P2P streaming.     

A PSO method with nonlinear time-varying evolution for optimal design of PID controllers in a pendubot system

A particle swarm optimization method with nonlinear time-varying evolution (PSO-NTVE) is employed in designing an optimal PID controller for asymptotic stabilization of a pendubot system. In the PSO-NTVE method, parameters are determined by using matrix experiments with an orthogonal array, in which a minimal number of experiments would have an effect that approximates the full factorial experiments. The PSO-NTVE method and other PSO methods are then applied to design an optimal PID controller in a pendubot system. Comparing the simulation results, the feasibility and the superiority of the PSO-NTVE method are verified.     

基于改进遗传算法的非线性系统模糊辨识新方法

提出一种基于改进遗传算法和递推最小二乘的非线性模糊辨识新算法.该辨识方法包含结构辨识辨出和参数辨识,结构辨识即输入空间的模糊划分,采用具有自适应性的广义高斯隶属函数;参数辨识包含前提参数和结论参数,用基于动态比例变换的改进遗传算法优化高斯函数的前提参数,用递推最小二乘辨识模糊模型的结论参数.最后通过著名的Box-Jenkins煤气炉数据仿真(仿真环境:MATLAB 6.5,计算机主频2.4 GHz,内存512 MB),并根据输入变量个数和模糊规则数,得到均方误差以证明本文方法的辨识精度,将该文辨识方法与其他方法进行比较,验证了该方法辨识精度更高.     

CO_2焊接基于模糊的电流波形控制系统研究

针对ＣＯ２焊接存在的问题，提出了ＣＯ２焊接基于模糊的电流波形控制方案。基于模糊控制理论和大量ＣＯ２焊接工艺实验结果，对ＣＯ２焊接基于模糊的电流波形控制系统进行了研究，并对其进行了８０９８单片微机程序设计；应用该系统对碳钢ＣＯ２焊接进行了应用研究，实验结果表明，达到了设计要求。     

Realization of sliding motion in a nonlinear stabilization system based on the method of the Lyapunov function

In this article, an approach is suggested for obtaining a sliding mode in nonlinear stabilization systems on the basis of the general stability theory. As an indicator of the stability, a time derivative is used of a decomposable quadratic form in phase variables. From the condition that the derivative is negative, two simultaneously operating kinds of control are obtained: an equivalent control that transforms the system into a linear one with a switching curve as its phase trajectory, and a high-frequency control that provides sliding motion along this curve. For the purpose of saving energy, a border layer is introduced. In this case, the sliding motion takes place at the border layer boundary, while inside the zero control is enabled. The results are modeled by means of the Simulink package, which is a part of the Matlab application.     

应用有限元研究稀土电解槽温度场

运用傅立叶方程建立了氟化体系稀土电解槽的温度场的有限元模型,采用VC6.0编程制作了相应的软件,并对导热系数、密度、比热等相关参数进行了运行计算研究。结果表明,建立的数学模型和编制的软件对稳态温度场的数学模拟计算结果与实际测试的结果基本吻合。可为新一代稀土电解槽体的开发设计提供参考。