河道漫滩及湿地上淹没柔性植物水流的紊流特性

植物在河流生态的修复中起重要作用,因此对含植物明渠水流的紊流机理的研究显得非常重要。将河漫滩及湿地中含淹没柔性植物的水流视为充分发展了的紊流,在实验室中用特定材料模拟柔性植物,通过水槽试验用三维ADV对淹没柔性植物段紊流特性进行了测量研究,对试验结果计算分析表明含淹没柔性植物的垂向流速分布不再符合指数分布;其紊流具有明显的各向异性特性;植物冠层交界处,水流紊动交换强烈,该处紊流强度及雷诺应力出现最大值。     

防洪调度图在二滩水库调度中的应用

二滩水库是以发电为主的大型水库,因设计时不承担下游的防洪任务,正常高水位以下未留防洪库容,水库在汛期要长期弃水运行,防洪调度比较被动。本文以二滩水库为例,根据不同入库流量编制出二滩水库防洪调度图,依据入库流量大小预留出相应的防洪库容,不但解决了防洪与发电之间的矛盾,使二滩水库获得可观的防洪库容和较大的防洪效益,而且为金沙江下游及长江干流的防洪削峰、错峰创造了条件,还可为汛末蓄水关闸时间的选择提供了可靠的依据。该防洪调度图也是汛期水库防洪、发电和水位控制的实时调度图,应用灵活主动,并可在其他以发电为主(或引水较有规律)的大型水库应用和推广。     

伪波阻抗反演在准噶尔盆地永进油田储层描述中的应用

永进油田目的层产状平缓,断层不发育,储层厚度小、埋深大、描述困难。运用伪波阻抗技术对该区的储层进行了研究,取得了较好的效果。     

三种新型流量计在醋酸装置中的应用

阐述了阿牛巴、超声波、电磁等3种流量计的性能特点、选用原则和安装要点。重点分析了低压甲醇羰基化生产醋酸装置中的各种介质的特点如强腐蚀性、两相流、低电导率等,根据不同介质的特点和工艺要求选用不同类型的流量计,并且总结了这些流量计替代原有孔板、涡街、涡轮流量计的实际使用情况以及经验教训。     

改进的第三代相干算法及应用

在讨论相干技术发展及三代相干算法优缺点的基础上，介绍了改进的第三代相干算法。应用自行开发的相干软件对多个油气勘探和开发区块的三维地震资料进行处理、分析，对相干时窗长度、相关道数等参数对算法效果的影响及相干体对断层、异常地质体的识别，以及解释方法进行了探讨。应用实例证明，改进的第三代相干算法抗干扰能力强，横向分辨率高，不仅适用于倾斜地层，而且对断层尤其对小断层、异常地质体具有较高的检测能力，是油气勘探和开发的一项有效和实用的技术。     

Public grid computing participation: An exploratory study of determinants

Using the Internet, “public” computing grids can be assembled using “volunteered” PCs. To achieve this, volunteers download and install a software application capable of sensing periods of low local processor activity. During such times, this program on the local PC downloads and processes a subset of the project's data. At the completion of processing, the results are uploaded to the project and the cycle repeats.     

黄河2007年汛前调水调沙生产运行分析

对黄河2007年调水调沙生产运行情况进行了分析,结果表明:本次调水调沙取得了下游河槽全线冲刷、主河槽最小平滩流量由调水调沙前的3 500 m3/s增大到3 630 m3/s和人工塑造异重流成功等良好效果。取得的主要收获有:①进一步积累了人工塑造异重流的经验;②加深了对下游河道水沙演进规律的认识;③为河道整治工程设计提供了原型观测数据;④再次证明调水调沙作为扩大下游河道排洪能力、处理黄河泥沙、维持黄河健康生命的措施之一是行之有效的。     

Income, Time Effects and Direct Preferences in a Multimodal Choice Context: Application of Mixed RP/SP Models with Non-Linear Utilities

Transport problems typically involve at least two types of constraints, on income and on time. Therefore, the indirect utility function depends either on the income available after having subtracted the cost of the discrete alternative and on the free time left after having worked and travelled by each competing option. In the typical linear-in-the-attributes and in-the-parameters specification, that represents the first grade approximation of the indirect utility function, the effect of income and time constraints cancel out and only the cost and time of the alternatives matter in the comparison between them. From a microeconomic point of view this is equivalent to assume that income and time effects could be disregarded; which is not always the case. To account for these effects the utility function should include second order attributes; however, in non-linear utility functions it may not be easy to distinguish among several effects that could be relevant: direct preferences for good and leisure, and simple interactions between attributes other than income and time effects. This paper analyses these effects from a theoretical point of view focusing on the possible confounding problem in detecting income and time effects. We use a dataset collected for a modal choice context and containing both revealed and stated preference data, and estimate several NL models examining the effect of the different second-order terms on detecting income and time effects. We compared specifications including square cost and time attributes, interactions between time and cost, cost divided by the income available to be spent on free time, and time multiplied by free time. Our results confirm the strong effect of direct preferences for goods and leisure time on choice, and the potential confounding effect between quadratic attributes and other non-linear omitted terms. Finally, we also found that care should be taken in highlighting income and time effects using mixed data sources, since confounding effects can occur when non-linearities are accounted for in both data sets.     

提高检测数据准确性 促进选钼生产稳定高效

本文从6个方面对选钼2个作业段的取样方式进行了校验,通过对检测数据的比对分析,找出了选钼2个作业段数据存在矛盾的原因,并针对原因采取了有效的措施,保证了检测数据的准确性,促进了选钼生产的稳定高效。     

Minimum spanning trees made easier via multi-objective optimization

Many real-world problems are multi-objective optimization problems and evolutionary algorithms are quite successful on such problems. Since the task is to compute or approximate the Pareto front, multi-objective optimization problems are considered as more difficult than single-objective problems. One should not forget that the fitness vector with respect to more than one objective contains more information that in principle can direct the search of evolutionary algorithms. Therefore, it is possible that a single-objective problem can be solved more efficiently via a generalized multi-objective model of the problem. That this is indeed the case is proved by investigating the computation of minimum spanning trees.This work was supported by the Deutsche Forschungsgemeinschaft (DFG) as part of the Collaborative Research Center Computational Intelligence (SFB 531) and by the German-Israeli Foundation (GIF) in the project Robustness Aspects of Algorithms.