基于分布浮力式的海底管道侧向屈曲控制优化

不加控制的侧向屈曲严重威胁深海油气输送管道的安全运行.分布浮力式海底管道侧向屈曲控制技术中,各个分布浮力模块对管道系统有效轴向载荷有较强的耦合作用,必须进行合理设计.为提高对管道系统侧向屈曲的控制效果,基于弹性解析模型,对大尺度海底管道系统侧向屈曲分布浮力式控制技术中浮力模块的设计参数以及布置方案进行了优化设计.算例结果表明,优化设计方案通过合理设计分布浮力模块参数以及布置方案,减少了管道系统侧向屈曲长度,降低了整体的有效轴向载荷,使侧向屈曲位移得到了较好的控制,为优化设计方法在海底管道工程中的应用提供了参考.     

大高差长输供热管线中继泵站设置分析

目的研究大高差下长输集中供热干线中继泵站的设置条件,中继泵站在供热干线中的理论设置范围,中继泵站位置对长输供热干线上各种泵扬程的影响.方法采用传统的水力计算方法和流体动态模拟分析软件(AFT Fathom10),对山西省阳城电厂拟向晋城市区供热的23 km长距离供热输送管线进行可行性分析,研究在大高差下供热管道内的压降规律.结果 AFT Fathom模拟得出管线压力曲线,中继泵站的设置条件,得出了满足工况要求的中继泵站设置范围为距供热首站3 785～10 222 m.系统循环泵扬程为97.7 m,中继泵扬程为54.6～113 m,系统总扬程为210.7 m.AFT Fathom模拟管道压力可知大高程差对管道压力有着明显的影响;水压图分析可以确定系统中各泵的扬程及运行所需总扬程,且所需总扬程保持定值.结论设置中继泵站与隔压站相结合的供热工程方案,在大高差下可以同时满足输送干线及城区一级管网的压力等级.在满足输送需求的水力工况基础上,在中继泵站设置范围内,可现场勘察选出最合适的中继泵站设置位置.     

莫合台镇集中供热管网改造

分析了莫合台镇集中供热管网的主要特点,从管网布置、供热指标计算、管径选择、水力平衡、管道敷设及保温材料的选择、原有管道的利用等方面介绍了该镇供热管网的设计改造,并总结了设计中的几点体会。     

考虑部件经济相关性的风力机系统状态维修优化

在考虑部件维修活动之间的经济相关性的基础上,研究多部件系统状态维修优化问题.利用随机过程描述部件性能退化过程,采用等周期检测方式在检测点处根据部件的退化状态分别采取最小维修、预防性维修或者事后维修等维修方式.基于更新过程建立状态维修长期运行平均成本率模型,考虑部件维修之间存在的经济相关性,建立多部件状态维修优化模型.以主轴、齿轮箱、发电机等部件组成的风力机为例,研究多部件系统最优检测周期,分析模型参数对维修成本、维修决策的影响.案例研究表明:该模型可以有效描述风力机多部件系统的维修优化问题,考虑部件之间的经济相关性,有利于降低维修费用.     

离散时间系统的最优预防性维修周期模型

针对预防性维修计划在可靠性工程中的重要性,该文对离散时间参数下的可修系统进行了研究.文中假定系统寿命、修复性维修和预防性维修的修复时间均遵从一般的离散分布,修复为完全修复,建立了考虑预防性维的系统瞬时可用度模型和平均可用度模型.在此基础上,建立了以平均可用度为指标的最优预防性维修周期模型.该文通过一组数值算例对该最优维护模型的有效性进行了验证说明.     

多源复合式供热系统多目标优化控制策略研究

近年来,太阳能与热泵技术相结合的应用日益普及.本文以太阳能集热系统、空气源热泵以及电锅炉为供热源组成的复合式供热系统为研究对象,通过建立复合系统多目标优化模型,结合其运行特点和控制理论,应用改进的多目标人工蜂群算法对多源复合式供热系统的运行参数进行优化,并提出多目标优化控制策略.结果表明,优化后的控制策略大幅提升了该系统的整体性能,所得能效比提高了约12%,明显优于传统的单一最优解优化结果,为多源复合式供热系统的推广使用提供了可能.     

部件串联的Geometric／G／1可修排队系统费用模型

研究一个部件串联的离散时间Geometric／G／1可修排队系统的费用优化策略。考虑服务台的服务率是可控制的,顾客的到达时间和服务时间均服从几何分布,给出系统的费用参数模型,并结合数值计算实例分析了系统的各参数对系统的最优平均服务时间和最优费用的影响。     

长沙地区居住建筑外墙保温层最佳厚度的研究

考虑太阳辐射对墙体传热的影响,运用P1-P2经济性模型对寿命周期内保温层最佳厚度进行了研究,并对长沙市居住建筑8个朝向和3种外表面颜色的典型外墙的保温层最佳厚度进行了计算.分析了现值因数、基层热阻和气候因素对选定的5种保温材料最佳厚度的影响,提出了根据保温材料的性价指标确定最优保温材料的方法.结果表明,膨胀聚苯乙烯由于寿命周期内的总投资现值最低,收益净现值最大,为5种保温材料中的最优材料.考虑到外墙朝向的影响,不同朝向的外墙,其保温材料宜采用不同厚度;外表面为深色的东北向外墙采用最佳厚度保温层带来的寿命周期收益最大,浅色的南墙最小.     

基于弹性波的预应力管道灌浆密实度定性检测与分析

为了提高预应力管道灌浆密实度定性检测的精度,针对1片20 m长的模型梁进行预应力管道灌浆密实度定性检测。首先,通过简化建立了弹性波首波在管道中的一维传播模型,提出首波慢度与灌浆密实度之间的线性表达式。然后,根据传播模型浇筑1片20 m长的模型梁,模型梁内含有5根具有不同灌浆密实度的预应力管道;利用弹性波激发与采集装置对模型梁中的预应力管道进行灌浆密实度定性检测,通过循环采样的方式进行数据采样;对采样数据进行数据处理,通过首波位置自动判断算法和最优滤波参数选择方法等手段,得到被检管道的首波慢度。最后,利用首波慢度与灌浆密实度线性公式,计算出被检管道的灌浆密实度,并将结果与设计值进行对比分析。结果表明:弹性波首波慢度与管道灌浆密实度之间呈线性关系;检测结果与设计值之间的相对误差约为5%。所提出的循环采样、首波位置自动判断和最优滤波参数选择等方法,可用于实际的预应力管道灌浆密实度定性检测,提高检测精度。     

公路用玻璃钢夹砂管道径厚比优化

为解决公路用玻璃钢夹砂管管壁厚度设计缺乏标准与依据的问题,通过对玻璃钢夹砂管道试样进行压缩性能试验、拉伸性能试验获得不同管壁厚度的基本力学参数;结合在役玻璃钢夹砂管道的现场静载试验,得到在车辆荷载作用下玻璃钢夹砂管的变形规律,采用ABAQUS软件建立玻璃钢夹砂管道在车辆荷载作用下的数值分析模型,以路面基层材料劈裂强度值及管道最大允许变形量为控制指标,研究不同管道内径、不同管道埋深8种工况下玻璃钢夹砂管道的径厚比的最优取值。研究结果表明:管道的最优径厚比与管道内径及管道覆土深度有关,当管道内径为1.0m,管道覆土深度分别为1、1.5、2m时,管道的最优管壁厚度范围分别为20~25、25~30、32~37mm,最优径厚比范围分别为40~50、33~40、27~31;当管道内径为1.5 m,管道覆土深度分别为1、1.5、2m时,管道的最优管壁厚度范围分别为28~33、32~37、35~40mm,最优径厚比范围分别为45~53、40~46、37~42;当管道内径为2.0m,管道覆土深度分别为1.5、2m时,管道的最优管壁厚度范围分别为35~40、40~45mm,最优径厚比范围分别为50~57、37~44。在保证道路整体结构以及管涵自身结构安全的前提下,可根据管道内径以及管道覆土深度选择最经济的管壁厚度,从而节省管道原材料成本,减小玻璃钢夹砂管涵洞工程的造价。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

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.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the