制冷系统仿真中定量参数的神经网络辨识

尝试用现代人工智能技术来改进现有的制冷系统仿真方法．首先，提炼出与制冷系统仿真结果的量化密切相关的定量参数，然后在已有的定性数值仿真模型的基础上，根据实验数据，采用人工神经网络（ＡＮＮ）方法对仿真模型中的定量参数进行辨识，识别出最佳的定量参数．这不仅有利于提高仿真精度，改善计算稳定性，而且降低了对仿真软件用户的技术要求，有利于仿真技术的实用化．对房间空调器稳态特性仿真的初步结果表明该方法效果良好．     

基于满意聚类的非线性系统多模型建模方法

针对一类生产过程中存在严重非线性的系统，基于系统运行中积累的可靠的输入／输出数据，提出了一种新的多模型建模方法．根据对各种指标的满意要求，对数据进行二次聚类，不仅得到了更有效的系统多模型，而且得到了每个模型的适用域．与模糊聚类和建立T—S模型方法相比，本方法不依赖系统的先验知识和预先定义模糊隶属度，具有良好的泛化性．以pH中和过程为例进行了仿真研究，验证了该方法简单易用，有很高的建模精度，并对存在的数据不确定性具有一定的鲁棒性．     

吸收式制冷系统动态模型的分析与建立

吸收式制冷系统具有两相及两组分流体流动以及多个部件数，其动态模型的建立与求解比较复杂。这里采用面向对象的模块化的仿真建模方法，将吸收式制冷系统分解为两个子系统，根据一定参数耦合关系相连接，建立其部件和系统的动态模型，适用于双效的各种溶液流程的吸收式制冷系统运行特性的仿真研究。动态仿真计算结果与实验数据的对比显示了较好的吻合性。     

多变量耦合系统--大姿态复合运动三轴平台的建模及仿真

在惯性制导系统中，三轴平台为载体提供了精确的姿态信息，当载体作大姿态复合运动时，三轴平台是一个非线性、时变的多变量耦合系统，其模型十分复杂，建模也非常困难．通过详尽的动力学分析为平台台体推导出完整的运动方程，并对此进行线性化处理，进而根据实际结构建立了系统模型框图，最后，采用面向对象建模技术（ＯＭＴ）对系统进行了计算机仿真．仿真结果表明，大姿态复合运动的平台仍具有较高的姿态控制精度，并验证了将二阶小量忽略的线性处理方法既可以简化模型，又不会影响模型的各项精度．     

基于有限元法与田口法的V形件冲压仿真参数稳健设计

提出了一种有效的冲压仿真参数稳健设计方法，该方法将有限元分析方法和田口法有效结合．以V形件冲压过程为对象，首先分析各建模参数对稳健性仿真实验设计的影响，并就各因子的水平选择进行了研究，寻求有利于提高稳健性的建模参数组合．利用有限元软件ABAQUS建立了V形冲压件的有限元仿真模型，得到仿真实验设计结果．运用田口分析方法，进行了V形件冲压加工建模参数的稳健性设计分析，给出了实物试验结果，对仿真实验结果进行了验证分析．本研究为有效进行稳健设计提供了一种简单、实用的方法．     

基于ANFIS的油耗特性建模及燃油经济性仿真

根据试验数据对发动机燃油消耗特性进行回归分析是一种常用的方法，但存在建模精度不足的缺点．采用MATLAB提供的自适应神经模糊推理系统ANFIS对NJG415汽油发动机油耗特性进行建模，在此基础上对装有该发动机的NJ6400GHR旅行车燃油经济性进行仿真，并与回归方法进行对比分析．研究表明ANFIS具有很好的逼近非线性特性的能力，具有较高的建模精度，可用于非线性系统的建模和仿真．     

电子膨胀阀动态特性的辨识

针对制冷系统蒸发器过热度随ＥＤＭ型电子膨胀阀开度变化的关系模型，对电子膨胀阀的步进电机施以电脉冲驱动，从而获得蒸发器过热度作为动态响应的运行规律，并应用８种系统辨识方法对该制冷系统进行辨识．经过对各种辨识方法辨识结果的比较，给出各种辨识方法在处理这一类问题时的辨识精度，以及在具体处理过程中的特点，给出适于这一类模型的辨识方法．同时，也说明了该环节用一个三阶环节描述更接近实际情况，这为以后制冷系统模拟、仿真奠定较好的基础．     

基于脉冲波形积分法的三电平变换器的统一建模

针对三电平DC-DC变换器开关数目多，开关模态复杂，难以用传统建模方法对之进行统一建模，用脉冲波形积分法对三电平DC-DC变换器进行建模分析，得到了有效的统一模型．文中以Buck三电平DC-DC变换器为例，详细阐明了统一建模原理，并给出了三电平DC-DC变换器的统一建模方法．仿真分析与实验验证了理论分析的结果，表明基于脉冲波形积分法对三电平DC-DC变换器进行统一建模是行之有效的．     

无人机倾斜摄影在城市三维建模中的应用研究

为了验证旋翼无人机倾斜摄影测量的可行性及精度,该文以北京市高新区为例,采用旋翼无人机对其进行了倾斜摄影,利用ContextCapture进行了三维实景建模,并采用外业实测控制点、检查点及测量数据对模型的平面精度及测量精度进行了验证,最终对基于旋翼无人机倾斜摄影测量技术进行三维实景建模的可行性、精度及效率做出客观评价,为后期的行业应用提供了一定的技术参考。     

制冷系统蒸发器动态过程数学模型模糊辨识

建立制冷系统动态过程数学模型是实现制冷装置优化控制的重要基础.制冷蒸发器是一类过程复杂的两相流动与换热系统,具有明显的非线性和不确定性,其精确的机理模型难以建立.该文通过熵方法和竞争学习算法对输入空间进行聚类,利用递推最小二乘辨识算法(RLS)确定模型的结论参数,实现了蒸发器动态过程数学模型的在线模糊辨识.通过仿真实例,验证了模糊辨识方法对于制冷系统蒸发器在线建模过程的有效性,所建立的模糊规则模型不仅具有较高的辨识精度,同时还具有较为理想的泛化性能和在线跟踪能力.     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

英文诗歌中的喻类修辞

为了有助于提高英文爱好者的个人情操、文化素养和学习兴趣,以及专业人员对英语学习和研究进行多途径的探索,本文通过一些精选诗歌的引证和分析,着重论述了喻类修辞法在英文诗歌中的运用其及效果。     

Man Is Unable to Change the Miserable Life——Analysis of the Arrangement of Four Characters in The Glass Menagerie

Tennessee Williams is considered as one of the most important American playwrights since World War II.The Glass Menagerie is his first successful drama,which describes a tragic situation of family and means to say that Man is unable to change the miserable life,no matter whatever means he try,This essay focuses on the analysis of the arrangement of the four main characters:Laura.Amanda,Jim and Tom to reveal the theme.Laura is fragile.Amanda is brave.Jim is vital.Tom is sensible.And all of them develop and try the different means to struggle against life,but fail tragically.With the evidence,the paper comes to conclusion naturally that Man is unable to change the miserable life,and he dooms to fail.     

Characterization of root-nodulating bacteria on Retama raetam in arid Tunisian soils

The aim of this study is to investigate the diversity of Retama raetam root-nodule bacteria isolated from arid regions of Tunisia. Twelve isolates, chosen as representative for different 16S rRNA gene patterns, were characterized by 16S rRNA gene sequencing and phenotypic analysis. Isolates were assigned to Sinorhizobium, Rhizobium and Agrobacterium. Symbiotic properties of Sinorhizobium and Rhizobium isolates showed a large diversity in their capacity to infect their host plant and fix atmospheric nitrogen. Strain RK 22 identified as Rhizobium was the most effective isolate.     

An Affordable Accurate Evaluation of the Binding Conformations Predicted by Molecular Docking Studies in Bio-System

正Recently,docking has been widely used to predict the binding-modes of protein-inhibitors,when the crystal complexes structure was absent.Most docking algorithms are able to generate a large number of probable conformations,it,however,is difficult to effectively evaluate these docking poses and identify the most reasonable bindingmode.In the present study,on the basis of the crystallographic data of human 3-hydroxy-3-methylglutaryl coenzyme     

WIMAX与WI-FI技术分析及联合组网

介绍了WiMAX与Wi-Fi两种无线宽带接入技术,并对两者之间的关系及相互之间的影响做了对比及分析,并对WiMAX的关键技术进行了详细说明,最后对两者的联合组网方式做了简单的探讨。