陕西交口抽渭多级泵站优化调度研究

泵站工程对工农业生产的发展有着非常重要的作用。根据泵站优化调度数学模型求解方法,结合交口灌区泵站的实际情况,采用动态规划和模拟技术相结合的方法以总能耗最小为目标函数建立数学模型,模型采用站内机组的优选和多级泵站系统的优化进行求解,用动态规划法确定每级泵站的机组最优开机组合,然后模拟了系统的运行,计算出各级泵站之间的优化水位组合,对交口灌区多级泵站实施优化调度,经实践研究表明,模型是可行和实用的。     

泵站优化调度的分解协调模型

针对泰州泵站中转浆式与定桨式轴流泵机组同时并存的情况，依据其常规调度模式和机组布置的特点，引入大系统分解协调技术，建立了两层谱系结构的泵站优化调度模型，并在不同层次采用了合理的优化进行求解，计算结果表明，所提出的模型及优化原则保证了泵站在原有设施条件下能经济高效地运行。     

离心式泵站并联调速运行的优化控制

通过对离心式水泵高效工作区的性能曲线进行二次拟和,分析离心式水泵机组并联调速运行特性.以机组最小功耗为目标函数,以系统流量为约束条件,建立泵站并联调速优化运行控制的数学模型.将不同转速泵并联调速的最优控制问题转化为求解多元函数条件极值问题,采用拉格朗日乘数法和非线性方程的Newton解法求解该模型,得到并联调速机组优化运行时工况点的计算方法.仿真结果证实该模型有效、可行,给出的优化控制方法可以在一定程度上节约泵站的运行成本.     

江都四站站内多机组变角优化运行方式研究

以南水北调东线源头泵站江都四站为例,建立了考虑峰谷电价的站内多机组日变角优化运行非线性规划模型.以站内机组耗电费用最少为目标函数,时段为阶段变量,水泵叶片角、开机机组台数为决策变量,日抽水量为约束,采用动态规划逐次逼近的方法,对江都四站进行计算分析,确定了不同水量约束条件下泵站机组的开机台数与水泵叶片角.结果表明,该模型可有效解决站内机组优化运行问题,效果良好.     

含储能系统及风电的电力系统动态经济调度

风电的随机性和波动性给传统的调度带来困难,为此在模型中引入储能系统,分析了储能系统对含风电的电力系统经济调度的影响,尤其是对系统调峰的影响。将含风电和储能系统的经济调度描述为一个非线性优化问题,建立了一个风电场与储能系统相配合的清洁经济调度模型,其目标函数在传统火电机组运行费用的基础上兼顾了火电的排污成本,寻求经济和环保总成本的最优解,采用粒子群算法对该模型进行求解。通过6机系统算例分析,表明该模型能够有效地控制储能系统的出力;储能系统的引入可明显降低系统的运行费用,尤其是火电机组调峰的费用,且提高了风能利用率。     

含储能系统及风电的电力系统动态经济调度

风电的随机性和波动性给传统的调度带来困难﹐为此在模型中引入储能系统﹐分析了储能系统对含风电的电力系统经济调度的影响﹐尤其是对系统调峰的影响。将含风电和储能系统的经济调度描述为一个非线性优化问题﹐建立了一个风电场与储能系统相配合的清洁经济调度模型﹐其目标函数在传统火电机组运行费用的基础上兼顾了火电的排污成本﹐寻求经济和环保总成本的最优解﹐采用粒子群算法对该模型进行求解。通过6机系统算例分析﹐表明该模型能够有效地控制储能系统的出力;储能系统的引入可明显降低系统的运行费用﹐尤其是火电机组调峰的费用﹐且提高了风能利用率。
     

风火联合系统的多目标随机优化调度方法的研究

考虑到风电场出力的随机性,以常规机组燃煤费用最小、污染气体排放量最小为目标函数,约束条件以概率的形式表示,构建考虑机组组合的风火联合系统的多目标随机机会约束规划模型。结合机组启停优先顺序表,采用启发式搜索策略确定机组组合状态,以避免机组频繁启停或系统容量冗余。采用基于Pareto的多目标粒子群优化算法,结合随机模拟技术和模糊逻辑评价法,对既定机组进行经济负荷分配。以含10机的风火联合系统为算例,验证了所提调度方法的可行性、有效性。优化调度结果表明:1该模型能够充分利用清洁能源,降低系统运行成本,减少污染气体排放量,提高电力系统运行的综合效益;2该算法计算精度高,速度快,避免了基本粒子群优化算法易陷入局部最优的缺点。     

燃气溴化锂吸收式制冷机运行的模拟及优化

结合实际的测试数据，利用神经网络反向传播网络BP算法，辨识出机组的系统模型，对机组的运行特性进行分析，并采用同样的方法对机组的运行费用进行建模和优化．研究结果表明，采用人工神经网络能很好地解决溴化锂机组的建模问题，并可根据模型对机组的运行特性进行分析．     

模拟退火遗传算法的泵站优化运行

针对泵站在不同流量扬程要求时，水泵运行组合不合理，导致泵站运行效率低的问题，提出以泵站总功率最小为目标函数的优化运行数学模型.此模型以水泵扬程、总供水量和调速泵的调速率为约束条件，利用模拟退火遗传算法确定并联运行泵的台数、调速泵的调速率及泵的流量分配，实现泵站的优化运行.该算法引入了不可行度对每代种群做初始选择，并利用不可行度取代传统的惩罚函数，平衡目标函数最优化和满足约束条件这两方面的要求.最后通过实例验证了本算法在求解泵站优化调度问题方面的可行性.     

城市多水源供水系统一级优化调度模型及求解

针对南京市多水源复杂供水系统,建立了以运行费用为目标函数的一级优化调度模型,并采用遗传算法对其进行求解.优化调度结果表明:各泵站供水量、供水压力及A,B测压点的压力在满足用户供水要求的情况下得到了优化,调速泵站的调速作用得到了充分发挥,各泵站供水量得到了重新分配,供水压力及管网测压点的压力随之发生了变化,优化后的压力普遍变小且随时间变化较优化前平稳;为多水源供水系统一级优化调度提供了可行方法,并为泵站二级调度创造了条件.     

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.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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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.     

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     

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.     

Features of Women''s language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

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