汽液两相流键合图建模与仿真

为了研究汽液两相流管道系统动态特性,从质量守恒、能量守恒和动量守恒方程出发,采用交错网格有限体积法,推导出汽液两相流通用微分方程的离散形式,结合键合图理论建立了分段集总参数键合图模型.为了求解工质热力性质,利用多领域统一建模语言Modelica建立了键合图模型的仿真程序,并以直流锅炉受热管为例,在Dymola平台上进行仿真.仿真结果反映了热负荷阶跃变化时管内压力、温度、含汽率动态变化与分布情况,为管道系统设计与分析提供了依据.     

质子交换膜燃料电池稳态模型及仿真

质子交换膜燃料电池(PEMFC)发电装置具有高能效,低噪音,常温启动和环境友好等特点.文中将对PEMFC进行稳态建模,使模型能正确反映电堆的实际输出性能.PEMFC实验模型主要是通过实验方法,建立描述电池输出特性(输出电压与电流密度关系)的经验公式.为了提高模型的精度,以便模型能更好地反映真实的PEMFC电对性能,则需要对模型的参数进行优化.通过不同的Matlab优化函数对所建模型进行参数辨识,比较得出其中结果较好的对模型进行仿真,以验证模型的正确性.     

PEM燃料电池加湿器温度系统的模型辨识与控制

本文分析了质子交换膜燃料电池的膜加湿器系统,介绍了采用本课题组开发的NetCon控制器对加湿器系统进行数据采集和温度控制的系统集成方案。在此基础上辨识了加湿系统的温度模型,并采用变速积分PID控制算法控制加湿器的温度。仿真和实验结果表明,辨识得到的加湿系统温度模型能够准确地描述被控对象,本文采用的控制策略可以得到满意的控制效果。     

计算反射技术综述

计算反射技术是提高软件系统灵活性、可扩展性的重要技术。它使得软件系统具有自适应能力,在运行时随环境变化而改变自身,实现程序的动态演进。该文介绍了计算反射的基本概念、发展历程、方法分类、实现环境,帮助读者学习和掌握计算反射。文章的最后阐述了计算反射今后发展应重点关注的若干问题。     

Two-Equation RNG Transport Modeling of High Reynolds Number Pipe Flow

New solutions of two-equation RNG turbulence transport model are used to calculate high Reynolds number pipe flows. The results are compared with experimental Superpipe data of Zagarola et al. (1996) up to Reynolds number of 3.5 × 10⁷.     

面向信息流的安全模型与评估综述

对系统进行攻击的本质之一是在信息流动过程中的非授权泄露与修改,进而破坏系统的安全性,这使得非常有必要对信息流的安全进行分析。从安全保障目标和安全保障方式上对安全信息流模型进行了分类,综述了不同类型的信息流模型研究现状,分析了现有面向信息流的量化评估方法,展望了面向信息流安全评估的发展趋势。     

微生物燃料电池最大功率点跟踪方法综述

微生物燃料电池作为一种新型可持续发展的清洁能源得到广泛关注。因其本身固有特性的限制,微生物燃料电池产生的电能具有电压低、功率低、不稳定等缺点。通过微生物燃料电池的最大功率点跟踪控制,可以寻找微生物燃料电池的最大功率点,最大化提升其产电性能。对适用于微生物燃料电池的主要的最大功率点跟踪方法进行简要概括,重点对扰动观测算法、增量电导算法、电压调节法等方法的优缺点进行总结讨论,并对未来的进一步发展提出一些意见和看法。     

燃料电池电能与热能建模研究

为分析燃料电池的动态特性,对其发电和发热过程进行了建模研究。燃料电池划分为阳极动态模型、阴极动态模型、电化学电压模型和温度动态模型,分别从流量平衡、能量平衡和经验公式角度进行了机理建模;并采用改变负载和冷却水流量的方式进行测试。仿真结果表明,该模型能模拟燃料电池的电热动态过程,可用于辅助控制设计。     

Computational Mechanisms of Pulse-Coupled Neural Networks: A Comprehensive Review

Pulse-coupled neural networks (PCNN) have an inherent ability to process the signals associated with the digital visual images because it is inspired from the neuronal activity in the primary visual area, V1, of the neocortex. This paper provides insight into the internal operations and behaviors of PCNN, and reveals the way how PCNN achieves good performance in digital image processing. The various properties of PCNN are categorized into a novel three-dimensional taxonomy for image processing mechanisms. The first dimension specifies the time matrix of PCNN, the second dimension captures the firing rate of PCNN, and the third dimension is the synchronization of PCNN. Many examples of processing mechanisms are provided to make it clear and concise.     

Computational Challenges in Deciphering Genomic Structures of Bacteria

This article addresses how the functionalities of the cellular machinery of a bacterium might have constrained the genomic arrangement of its genes during evolution and how we can study such problems using computational approaches, taking full advantage of the rapidly increasing pool of the sequenced bacterial genomes, potentially leading to a much improved understanding of why a bacterial genome is organized in the way it is. This article discusses a number of challenging computational problems in elucidat...     

Multiphase Flow in Deforming Porous Media: A Review

In this work we present a general model for the analysis of multiphase flow in deforming porous media with particular regard to concrete and biological tissues. Such problems are typically multi-physics ones with overlapping domains where diffusion, advection, adsorption, phase change, deformation, chemical reactions and other phenomena take place in the porous medium. For the analysis of such a complex system, the model here proposed is obtained from microscopic scale by applying the thermodynamically constrained averaging theory which guarantees the satisfaction of the second law of thermodynamics for all constituents both at micro and macro-level. Furthermore, one can obtain some important thermodynamic restrictions for the evolution equations describing the material deterioration. Two specific forms of the general model adapted to the cases of cementitious and biological materials respectively are shown. Some numerical simulations aimed at proving the validity of the approach adopted, are also presented and discussed.     

Computational Fluid Dynamics in Turbomachinery: A Review of State of the Art

Computational fluid dynamics (CFD) plays an essential role to analyze fluid flows and heat transfer situations by using numerical methods. Turbomachines involve internal and external fluid flow problems in compressors and turbines. CFD at present is one of the most important tools to design and analyze all types of turbomachinery. The main purpose of this paper is to review the state of the art work carried out in the field of turbomachinery using CFD. Literature review of research work pertaining to CFD analysis in turbines, compressors and centrifugal pumps are described. Various issues of CFD codes used in turbomachinery and its parallelization strategy adopted are highlighted. Furthermore, the prevailing merits and demerits of CFD in turbomachinery are provided. Open areas pertinent to CFD investigation in turbomachinery and CFD code parallelization are also described.     

网络环境下社会管理的组织行为建模与计算实验研究综述

从网络环境下社会管理、组织行为与影响力建模、社会系统的计算实验、社会系统的探索性分析与优化设计四个方面对网络环境下社会管理的组织行为建模与计算实验的研究现状进行了综述. 在此基础上提出了相应的后续研究方向:网络环境下社会管理结构框架与运行机理、网络群体行为分析与影响力建模方法、社会管理的博弈机理、基于多智能体的社会管理计算实验方法和基于计算实验的社会管理策略探索性分析与评估.     

A Review of Digital Terrain Modeling

Terrains are a crucial component of three‐dimensional scenes and are present in many Computer Graphics applications. Terrain modeling methods focus on capturing landforms in all their intricate detail, including eroded valleys arising from the interplay of varied phenomena, dendritic mountain ranges, and complex river networks. Set against this visual complexity is the need for user control over terrain features, without which designers are unable to adequately express their artistic intent. This article provides an overview of current terrain modeling and authoring techniques, organized according to three categories: procedural modeling, physically‐based simulation of erosion and land formation processes, and example‐based methods driven by scanned terrain data. We compare and contrast these techniques according to several criteria, specifically: the variety of achievable landforms; realism from both a perceptual and geomorphological perspective; issues of scale in terms of terrain extent and sampling precision; the different interaction metaphors and attendant forms of user‐control, and computation and memory performance. We conclude with an in‐depth discussion of possible research directions and outstanding technical and scientific challenges.     

智能需求获取与建模研究综述

需求获取和建模是指从需求文本或记录中获取显式和隐式的需求,并通过表格化、图形化、形式化等方法构建相应模型的过程,是软件开发过程中极为关键的一步,为后续系统设计与实现铺平道路,提高软件开发效率和质量,提升软件系统稳定性和可行性.研究者们在需求获取与建模方面获得了一系列研究成果,根据其关注阶段不同,可以将它们分为需求知识提...     

区块链数据分析：现状、趋势与挑战

区块链是一项具有颠覆许多传统行业的潜力的新兴技术.自以比特币为代表的区块链1.0诞生以来,区块链技术获得了广泛的关注,积累了大量的用户交易数据.而以以太坊为代表的区块链2.0的诞生,更加丰富了区块链的数据类型.区块链技术的火热,催生了大量基于区块链的技术创新的同时也带来许多新的问题,如用户隐私泄露,非法金融活动等.而区块链数据公开的特性,为研究人员通过分析区块链数据了解和解决相关问题提供了前所未有的机会.因此,总结目前区块链数据存在的研究问题、取得的分析成果、可能的研究趋势以及面临的挑战具有重要意义.为此,全面回顾和总结了当前的区块链数据分析的成果,在介绍区块链技术架构和关键技术的基础上,分析了目前区块链系统中主要的数据类型,总结了目前区块链数据的分析方法,并就实体识别、隐私泄露风险分析、网络画像、网络可视化、市场效应分析、交易模式识别、非法行为检测与分析等7个问题总结了当前区块链数据分析的研究进展.最后针对目前区块链数据分析研究中存在的不足分析和展望了未来的研究方向以及面临的挑战.     

Challenges in Computational Analysis of Mass Spectrometry Data for Proteomics

Mass spectrometry is an analytical technique for determining the composition of a sample. Recently it has become a primary tool for protein identification and quantification, and post translational modification characterization in proteomics research. Both the size and the complexity of the data produced by this experimental technique impose great computational challenges in the data analysis. This article reviews some of these challenges and serves as an entry point for those who want to study the area in ...     

Modeling the Growth of Transportation Networks: A Comprehensive Review

This paper reviews the progress that has been made over the last half-century in modeling and analyzing the growth of transportation networks. An overview of studies has been provided following five main streams: network growth in transport geography; traffic flow, transportation planning, and network growth; statistical analyses of network growth; economics of network growth; and network science. In recognition of the vast advances through decades in terms of exploring underlying growth mechanisms and developing effective network growth models, the authors also point out the challenges that are faced to model the complex process of transport development.