气液分离器的结构优化

常规气液分离器一般采用重力沉降罐的结构形式,具有结构简单等特点,但设备体积庞大,占地面积大,处理时间长。基于计算流体动力学方法,采用Gambit建模,利用Fluent软件进行分析,对常规立罐式离心气液分离器进行了仿真。通过流场分析可以看出,流场对称性很差,底流出口附近气体含量较多,说明气液分离效果不好。通过结构优化,包括将底流出口改为正下方排液,单入口改为双入口结构,罐体直径减小,溢流管伸入分离器内部入口管之下,以及将分离器下端改为锥型结构等,经优化后改善了分离器内部流场的轴对称性及气相浓度分布情况,使分离效果有了明显改善,锥段的壁面和底流出口附近的含气量很低,提高了分离器的净化程度。通过实验研究说明优化后分离器的分离性能较好,而且通过实验也验证了仿真模型选取的正确性和准确性。     

聚碳酸酯液液分离器进料构件的流体力学模拟

测定了聚碳酸酯(PC)物料电导率随水油相体积比的变化,确定生产中物料为水包油型乳液,即分散相为PC胶液,连续相为水。采用F1uent商用软件对液液分离器内部流场进行了数值模拟,通过得到的分离器内部流线分布和轴向速度标准偏差分布,考察了不同进料口位置、挡板位置以及不同整流构件尺寸对液液分离器内部流场的影响。研究发现,进料口位置为中部,挡板位置距离进料口为50mm,整流构件开孔率为40%,长度为150mm时,分离器内的流场质量最佳,为液液分离器进料构件的进一步优化研究提供了参考。     

基于FLUENT的两种油气分离器分离效率分析

针对某型发动机的2种不同结构的油气分离器,采用FLUENT对流场进行数值模拟.使用RNG k ε模型计算连续相气体,得到油气分离器内部的流场速度分布.使用离散相模型（Discrete Phase Model,DPM）计算液态油滴,追踪离散项的运动轨迹,从而计算得到分离效率.探讨影响油气分离效率的因素,同时进行试验验证.结果可为油气分离器的后续优化设计提供参考.     

构件动态演化内部一致性保证方法

基于构件的软件开发已成为软件开发的主流方法,针对构件式软件动态演化后的一致性保持问题,目前大多数学者主要是从构件式软件的外部一致性角度进行分析和研究。为此,从构件内部的角度出发,提出一种保证构件式软件动态演化构件内部一致性的方法。首先,对构件及其相关模型进行建模,并给出了构件内部类有向图的同态映射关系的判定算法;其次,给出构件式构件动态演化内部一致性的标准,基于进程代数的强模拟理论和图论中的同态映射关系,分别从全局和局部的角度定义了构件式软件动态演化前后构件内部一致性标准的充分条件和必要条件,并对其进行了证明;然后,基于上述工作,给出了构件动态演化内部一致性保证方法的流程;最后,通过案例研究表明该方法的可行性和有效性。     

车用柴油机颗粒收集器收集特性的仿真分析

研究提高旋风式分离器优化效率问题,通过深入分析旋风式分离器的工作原理,设计了一款能有效降低柴油机颗粒排放的旋风式颗粒分离器。利用CFD软件对设计的旋风式分离器针对不同直径的柴油机排放颗粒的内部流场进行了仿真计算,研究旋风式分离器出口处的流场分布情况以及柴油机尾气颗粒直径的变化对压降和收集效率的影响关系,研究表明颗粒直径的变化对压降的影响很小,对收集效率影响较大。通过数值仿真,为设计旋风式分离器优化匹配柴油机提供了参考。     

基于FLUENT的气液分离器内流场仿真研究

基于计算流体动力学(CFD)方法,应用流体仿真软件FLUENT对两种气液分离装置内部流场进行仿真研究,得到分离器内部流场速度分布规律和相分布规律,发现合理改变排气通道的直径,可以提高分离效率。同时分析比较了流场模拟结果,发现排气通道直径改变处存在涡流。     

三元催化转化器内部流场的数值模拟

随着计算机技术的发展,数值模拟已经成为研究三元催化转化器的重要手段。本文在考虑冷态流场分布及将尾气看作空气做湍流的基本假设下,运用数值模拟软件FLUENT,采用四面体混合型网格,选取k-￡模型、多孔介质模型和质量入口等边界条件,建立了三元催化转化器的物理与数学模型,对三元催化转化器内部流场进行了数值模拟研究,获得了其内部压力场、湍动能及速度场的分布状况。研究结果表明,在扩压管附近、收缩管内壁和衬垫外壁之间均形成涡流区;三元催化转化器出口处速度场急剧变化,造成能量较大损失,因此要注重三元催化转化器扩压管与收缩管锥角的设计。随后运用所建立的模型对不同扩压管与收缩管长度下的三元催化转化器内部流场进行模拟,得出该工况下最优的三元催化转化器尺寸为收缩管长21 mm,扩压管长33 mm,并验证该尺寸下三元催化转化器工作状态较优。     

新型导流式旋流分离器的数学模型及仿真

新型导流式固-液旋流分离器在实际操作中存在参数无法确定的问题,设备经常跑粗.为了实际操作参数提供理论依据,并建立数学模型,运用流体力学公式结合T.D哈帝冈柱形旋流器模型建立了新型导流式固-液旋流分离器的数学模型.通过仿真,得出了旋流分离器的分流比、流量-密度-压强和分割尺寸-速度-压强等三维关系图.结果表明,实际工况中旋流分离器的分流达到近似固定值,分割尺寸范围广,适合在多种不同水域下工作.当旋流器的进料口速度在5m/s左右时,压强、离散相密度和流量呈局部线性关系且流场稳定.     

雷诺应力模型对旋流器内流场的数值模拟

深入研究了液-液水力旋流器的流动机理和分散油相的流动特点及处理方法，用计算流体动力学（CFD）的数值方法，采用雷诺应力（RSM）模型对油水分离旋流器的内部流场进行了数值模拟。分析了旋流器内部的体积浓度分布，压力分布，以及切向、轴向和径向速度分布的规律，揭示了油水两相流的分离特性。并且在不同流量下，计算出了旋流器的流量一效率曲线，计算结果与实验数据吻合较好，从而说明该湍流模型和数值算法的可靠性，同时也为进一步研究水力旋流器的分离机理、流场特性以及结构优化设计提供了一条有效的途径。     

新型气液旋流分离器的模拟研究

为了分离气液喷射反应器的产物,开发了一种新型气液旋流分离器。分别采用Muschelknautz模型、改进的Muschelknautz模型和计算流体力学(CFD)离散相模型对新型气液旋流分离器进行了模拟计算,对新型气液旋流分离器的压力场、分离效率、液滴运行轨迹进行了考察。结果表明:相对于传统Muschelknautz模型,改进的Muschelknautz模型与CFD的模拟结果更为接近,能更加准确地对旋流分离器的分离性能和压降进行预测:在设计条件下,液滴直径越小,颗粒在旋流分离器中的运动轨迹就越紊乱,>3μm的液滴颗粒的分离效率超过80%:颗粒的入口位置会影响颗粒的运动轨迹。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate