42 resultados para agent-based simulation


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The microgravity research, as a branch of the advanced sciences and a spe- cialized field of high technology, has been made in China since the late 1980's. The research group investigating microgravity fluid physics consisted of our col- leagues and the authors in the Institute of Mechanics of the Chinese Academy of Sciences (CAS), and we pay special attention to the floating zone convection as our first research priority. Now, the research group has expanded and is a part of the National Microgravity Laboratory of the CAS, and the research fields have been extended to include more subjects related to microgravity science. Howev- er, the floating zone convection is still an important topic that greatly holds our research interests.

目录

1. models of floating zone convection
1.1 floating-zone crystal growth
1.2 physical model
1.3 hydrodynamic model
1.4 mathematical model
references
2. basic features of floating zone convection
2.1 equations and boundary conditions
2.2 simple solutions of fz convection
2.3 solution for two-layers flow
2.4 numerical simulation
2.5 onset of oscillation
references
3. experimental method of fz convection
3.1 ground-based simulation experiments for pr≥1
3.2 temperature and velocity oscillations
3.3 optical diagnostics of free surface oscillation
3.4 critical parameters
3.5 microgravity experiments
3.6 ground-based simulation experiment for pr《1
.references
4. mechanism on the onset of oscillatory convection
4.1 order of magnitude analysis
4.2 mechanism of hydrothermal instability
4.3 linear stability analysis
4.4 energy instability of thermocapillary convection
4.5 unsteady numerical simulation of 2d and 3d
4.6 two bifurcation transitions in the case of small pr number fluid
4.7 two bifurcation transitions in the case of large pr number fluid
4.8 transition to turbulence
references
5. liquid bridge volume as a critical geometrical parameter
5.1 critical geometrical parameters
5.2 ground-based and mierogravity experiments
5.3 instability analyses of a large prandtl number (pr≥1)fluid
5.4 instability analyses of a small prandtl number (pr《1)fluid
5.5 numerical simulation on two bifurcation process
references
6. theoretical model of crystal growth by the floating zone method
6.1 concentration distribution in a pure diffusion process
6.2 solutal capillary convection and diffusion
6.3 coupling with phase change convection
6.4 engineering model of floating zone technique
references
7. influence of applied magnetic field on the fz convection
7.1 striation due to the time-dependent convection
7.2 applied steady magnetic field and rotational magnetic field
7.3 magnetic field design for floating half zone
7.4 influence of magnetic field on segregation
references
8. influence of residual acceleration and g-jitter
8.1 residual acceleration in microgravity experiments
8.2 order of magnitude analyses (oma)
8.3 rayleigh instability due to residual acceleration
8.4 ground-based experiment affected by a vibration field
8.5 numerical simulation of a low frequency g-jitter
8.6 numerical simulation of a high frequency g-jitter
references

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本文针对物理链路可靠性低、容错性要求高、实体异构程度高的基础设施网格化需求,在系统分析当前主流的网格体系结构的基础上,研究了移动代理(PVM)系统的特性,根据移动代理的特点,提出了基于移动代理的四层网格计算模型MAGC(Mobile Agent Based Grid Computing),描述了MAGC模型的层次结构,给出了MAGC模型的一个设计方案,分析了MAGC模型的特点,最后介绍了在Aglet平台下实现的原型系统。本文取得的成果主要包括: 第二章提出了基于移动代理的四层网格计算模型(MAGC),说明了模型中每个层次的功能和层次之间的依赖关系。MAGC模型基于代码迁移,可以解决网络环境恶劣的条件下,网格系统的运行与部署问题。设计了MAGC模型的两个重要基础结构:作业机制和消息机制。设计了移动代理平台抽象层,使网格系统独立于具体的移动代理平台,从而具有一定的可移植性。 第三章在MAGC模型的基础上,进一步给出了MAGC模型的一个实现方案,阐述了MAGC模型中四个子层的功能和组件划分,对每层所包含的组件和组件实现的功能进行了描述,说明了系统的启动方式。 第四章基于MAGC模型构建了一个原型系统,原型系统以IBM开发的Aglets移动代理软件包为基础,实现了作业机制、消息机制和MAGC模型中的移动代理平台抽象层、系统服务层、API层、应用作业层四个子层。

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文中提供了一种对植物叶子造型的新方法,可以非常真实地展现叶子在干枯、老化过程中几何形态的变化.基于植物学和物理原理,文中引入了双层结构模型表达叶子的力学结构,很好地模拟了不同种类植物叶子形状的多样性.文中首先分析了叶子形状变化的原因,即在叶子枯萎过程中,叶肉和叶脉由于各自不同的组织结构,导致了收缩比例不同,从而在物理模拟中,通过建立关于叶子基本结构的双层质点-弹簧模型,并对上下两层的不同参数的合理设置,很好地表现了叶肉和叶脉的不同力学特性.双层模型的相互作用,决定了叶子最终变形的方式和效果,由此可以得到非常接近真实树叶的各种叶子形态.

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作为空间环境效应之一的单粒子效应对航天器在轨道中的安全运行有着严重的威胁。为了清楚地认识这一效应的机制、机理,可以采用重离子加速器地面模拟的方法来研究这一效应。为此建立和完善了国内第一套基于重离子加速器的单粒子效应地面模拟实验装置,并在此装置上进行了Xe离子辐照IDT71256的单粒了效应实验。建立的基于兰州重离子加速器的单粒子效应地面模拟实验装置包括真空靶室系统和束流监测系统。实验用兰州重离子加速器提供的~(40)Ar完成了对整个装置的性能测试。结果表明:该装置能很好的满足单粒子效应研究的需求,真空靶室系统允许在不破坏真空的条件下更换器件,改变倾角,改变离子入射能量等。注量探测器实现了对弱束流非拦截式测量;能量探测器对Ar离子测量的偏差小于2%;束流均匀度探测器的位置分辨好于0.34mm。在这一实验装置上,用兰州重离子加速器提供的~(136)Xe对两片IDT71256的单粒子效应情况进行了模拟研究。结果发现:在两片器件中均观察到单粒子翻转和单粒子闭锁,而且两片器件均表现出明显的翻转不对称性,其中1→0的翻转约占总翻转数的90%。探讨了离子入射角、有效LET、和离子射程对翻转和闭锁截面的影响,发现除离子的有效LET以外,离子在器件中的射程也将在很大程度上影响器件的翻转和闭锁截面。

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“仿真是一种基于模型的活动”,任何仿真系统都不能离开模型的支持,如果每次开发新的系统都要重新建立模型,费时费力。随着仿真系统的日益复杂,导致仿真模型的结构也日趋复杂,模型管理亦日趋繁琐。因此,研究一种有效的模型管理方法,对于方便模型重用,提高开发效率有着重要的意义。实现对模型的有效管理,首先需要明确管理对象,然后把模型有条理的分类并且规范的描述出来,最后把模型存储在数据库中,供用户重用。论文首先在HLA联邦开发执行过程的基础上,分析和完善了HLA仿真建模体系,明确了HLA仿真中模型的层次;然后总结了现有的模型分类方法,从方便模型统一管理的角度,提出了一种可扩展的模型分类方法;引入了元数据和XML技术,实现了对模型的规范化描述;根据课题研究目的,提出了仿真模型管理系统的设计目标,并设计了系统的体系结构、功能模块和数据结构;最后,综合应用数据库、VC++等技术,实现了模型存储、模型的增、删、改、查以及用户管理等功能,实现了对于模型的统一管理。

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在激烈的市场竞争中,过程企业不仅要重视技术、更要加强管理,实现全局优化运行。提高过程企业的市场竞争能力必须全面综合集成人、组织、战略管理、经营管理、过程管理及信息自动化技术等因素。本文以石化企业为背景,对过程企业面临的问题及发展趋势进行了分析,并且对过程企业管理模式、过程企业的体系结构以及过程集成与优化技术进行了探讨。

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:综述了多机器人系统任务规划的研究 ,介绍了基于 Agent的分布协作式多机器人装配系统 ,给出了分布式多机器人系统任务协商规划算法 ,采用了改进的合同网协议方法。针对多机器人任务规划算法的软件实现 ,采用了先进的分布式对象技术 ,介绍了算法的具体实现方法

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本文介绍了我们建立的基于Agnet的分布协作式多机器人装配系统-DAMAS,在此基础上研究了多机器人合作的协商协议,采用了改进的合同网协议方法,针对多机器人协商协议的软件实现了,采用了应用前景广阔的分布式对象技术,介绍了机器人合作装配的协商协议的具体实现方法。

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Reliable turbulent channel flow databases at several Reynolds numbers have been established by large eddy simulation (LES), with two of them validated by comparing with typical direct numerical simulation (DNS) results. Furthermore, the statistics, such as velocity profile, turbulent intensities and shear stress, were obtained as well as the temporal and spatial structure of turbulent bursts. Based on the LES databases available, the conditional sampling methods are used to detect the structures of burst events. A method to deterimine the grouping parameter from the probability distribution function (pdf) curve of the time separation between ejection events is proposed to avoid the errors in detected results. And thus, the dependence of average burst period on thresholds is considerably weakened. Meanwhile, the average burst-to-bed area ratios are detected. It is found that the Reynolds number exhibits little effect on the burst period and burst-to-bed area ratio.

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To accomplish laser-induced thermal loading simulation tests for pistons,the Gaussian beam was modulated into multi-circular beam with specific intensity distribution.A reverse method was proposed to design the intensity distribution for the laser-induced thermal loading based on finite element(FE) analysis.Firstly,the FE model is improved by alternating parameters of boundary conditions and thermal-physical properties of piston material in a reasonable range,therefore it can simulate the experimental resul...

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A type of thermo-optic variable optical attenuator based on multimode interference coupler is proposed. The optical field propagation properties of the devices are simulated using finite difference beam propagation method. The propagation loss of the fabricated device is 2-4.2 dB at the wavelength range 1510-1610 nm. The total power consumption is 370 mW and the maximum attenuation is more than 25 dB, which almost can meet the requirements of optical fiber communication systems.

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In this paper, the SiC-based clamped-clamped filter was designed and fabricated. The filter was composed of two clamped-clamped beam micromechanical resonators coupled by a spring coupling beam. Structural geometries, including the length and width of the resonator beam and coupling beam, were optimized by simulation for high frequency and high Q, under the material properties of SiC. The vibrating modes for the designed filter structure were analyzed by finite element analysis (FEA) method. For the optimized structure, the geometries of resonator beams and coupling beams, as well as the coupling position, the SiC-based clamped-clamped filter was fabricated by surface micromaching technology.

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A novel CMOS-based preamplifier for amplifying brain neural signal obtained by scalp electrodes in brain-computer interface (BCI) is presented in this paper. By means of constructing effective equivalent input circuit structure of the preamplifier, two capacitors of 5 pF are included to realize the DC suppression compared to conventional preamplifiers. Then this preamplifier is designed and simulated using the standard 0.6 mu m MOS process technology model parameters with a supply voltage of 5 volts. With differential input structures adopted, simulation results of the preamplifier show that the input impedance amounts to more than 2 Gohm with brain neural signal frequency of 0.5 Hz-100 Hz. The equivalent input noise voltage is 18 nV/Hz(1/2). The common mode rejection ratio (CMRR) of 112 dB and the open-loop differential gain of 90 dB are achieved.