共查询到20条相似文献,搜索用时 140 毫秒
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本文主要是对垂直轴风力机风轮空气动力设计的研究。首先对各型垂直轴风力机的原理和设计特点进行了分析总结;其次,以多流管模型为理论基础,编写了可用于φ型达里厄垂直轴风力机性能预测的程序,且程序的可靠性很高;最后,利用FLUENT的滑移网格技术,对设计的风轮进行了数值模拟,结果表明,多流管模型应用于该风力机性能的预测精度很高。 相似文献
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电子商务在快速发展的同时也带来信息资源利用率较低、信息孤岛较多等问题。而网格技术“随需应变”的设计理念正是解决目前电子商务问题的关键所在。本文在介绍我国电子商务现状、网格技术的概念、特点及其应用的基础上,分析了网格技术在电子商务中的作用,提出随着网格技术和电子商务的不断深入发展,网格技术与电子商务的结合已势不可挡。 相似文献
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张旭 《中国高新技术企业评价》2014,(5):14-15
网格技术在很多领域都有所涉及,其应用范围很广,因此也被电力系统加以应用,网格技术在电力营销系统中有着重要的作用,并且网格技术能够与电力营销服务平台相结合,形成网络化的电力营销系统。文章就针对基于网格的电力营销服务平台设计进行深入的研究与分析。 相似文献
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本文首先详细阐述了网格的相关概念和特点,对网格技术进行了分类,并详细介绍了网格的核心管理技术。基于以上这些对网格和网格技术的分析,介绍了国内外一些有代表性的网格研究计划的开发进展,并指出了网格技术研究呈现的趋势。 相似文献
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信息时代的新星——网格 总被引:1,自引:0,他引:1
网格技术已成为目前的热门话题,文章介绍了网格的概念,并对信息网格和网格计算两种网格应用技术的原理及应用前景进行了详细论述。信息网格将利用现有的网络基础设施、协议规范、Web和数据库技术,为用户提供一体化的智能信息平台,而网格计算可为用户建立一个虚拟的高性能计算环境,提供超强的计算能力。 相似文献
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网格技术实现了网络资源的全面连通,会计信息网格将为会计信息管理提供跨越Web的信息分布和集成的应用平台。本文简要介绍网格技术的基本概念,阐述Intemet在会计信息管理应用中的不足。探讨网格技术在会计信息管理中应用的技术优势,并提出基于网格技术的会计信息管理系统的框架。 相似文献
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为了解城市公交信息化服务对公交乘客出行方式转移的影响,以上海市杨浦区为例,进行关于公交信息化服务下乘客出行方式转移的调查,获取个人属性、公交出行经历、公交出行评价、出行方式转移意向以及公交信息服务需求等信息。从公交信息使用者角度,重点关注公交信息化服务对乘客出行方式转移的影响,分别构建信息化服务情境下(公交到站时间与计划出发时间相差过大和车辆未在提示的时间内到达)的公交出行方式转移二项logit模型。模型结果表明:乘客平均候车时间、是否经常使用公交到站服务、是否有道路拥挤车辆未按时进站等原因而产生出行延误的经历、公交信息准确性评价与是否有必要提示同公交线路连续班次的到站时间等因素对不同情景下的乘客出行方式转移具有显著影响。 相似文献
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提出采用组合模型预测建筑物沉降,并以常用的三种建筑物沉降预测模型组成组合模型进行了计算分析,结果表明组合预测模型具有较高的预测精度,值得推广应用. 相似文献
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王春森 《中国高新技术企业评价》2007,(3):134-135,140
本文结合广州市城市快速公交系统的规划与设计,对城市快速公交系统的线路组织形式、与普通公交线路的整合、道路断面、车站四个方面对规划设计进行了探讨,为城市快速公交系统在我国的应用和发展提供借鉴。 相似文献
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近年来,现场总线技术在火电厂中得到了越来越广泛的应用,同时也在业内引起了更广泛的重视。文章对现场总线的结构特点和优势进行了分析,阐述了现场总线技术在智能化现场设备中的应用及智能化设备状态的检修管理等,并对现场总线技术在国内火电厂的应用情况进行了简单的介绍。 相似文献
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《Socio》2019
This article examines public procurements in the regional bus transportation sector. The data were collected exclusively for this research from regional offices in the Czech Republic. This study does not propose to estimate the cost function for bus operators, as do most efficiency studies. Rather, it’ focuses on identifying the factors that influence the final price offered by participants in the tender. Knowing these factors will help to properly set the tender conditions, which can further help to improve how well the bus operator functions, and to reduce public subsidies. The study also aims to estimate the technical efficiency rate by using Data Envelopment Analysis (DEA) and find the implications of efficiency scoring for tender conditions. This statistic also enables contract owners to compare the cost differences between individual bus service providers and examine companies that operate at the efficiency frontier. 相似文献
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《International Journal of Forecasting》2022,38(4):1492-1499
The M5 accuracy competition has presented a large-scale hierarchical forecasting problem in a realistic grocery retail setting in order to evaluate an extended range of forecasting methods, particularly those adopting machine learning. The top ranking solutions adopted a global bottom-up approach, by which is meant using global forecasting methods to generate bottom level forecasts in the hierarchy and then using a bottom-up strategy to obtain coherent forecasts for aggregate levels. However, whether the observed superior performance of the global bottom-up approach is robust over various test periods or only an accidental result, is an important question for retail forecasting researchers and practitioners. We conduct experiments to explore the robustness of the global bottom-up approach, and make comments on the efforts made by the top-ranking teams to improve the core approach. We find that the top-ranking global bottom-up approaches lack robustness across time periods in the M5 data. This inconsistent performance makes the M5 final rankings somewhat of a lottery. In future forecasting competitions, we suggest the use of multiple rolling test sets to evaluate the forecasting performance in order to reward robustly performing forecasting methods, a much needed characteristic in any application. 相似文献
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安徽省能源需求的组合预测 总被引:1,自引:0,他引:1
根据预测理论,结合安徽省历年能耗的数据,在建立能源需求单项预测模型的基础上,建立组合预测模型,对2008~2014年的能源需求量进行预测。结果表明:组合预测模型的精度高于单项预测模型;安徽省能源需求量正以较快的速度在增长。 相似文献
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BILL ROBINSON 《Economic Outlook》1983,7(10):24-41
This Briefing Paper is the last of a series of three about forecasting. In this one we examine our forecasting record; it complements the February paper in which we analysed the properties of our forecasting model in terms of the error bands attached to the central forecast.
There are many ways of measuring forecasting errors, and in the first part of this Briefing Paper we describe briefing how we have tackled the problem. (A more detailed analysis can be found in the Appendix.) In Part II we report and comment upon the errors in our forecasts of annual growth rates and show how our forecasting performance has improved over the years. In Part III we focus on quarterly forecasts up to 8 quarters ahead, and compare our forecasting errors with measurement errors in the oficial statistics; with the estimation errors built into our forecast equations; and with the stochastic model errors we reported last February. A brief summary of the main conclusions is given below. 相似文献
There are many ways of measuring forecasting errors, and in the first part of this Briefing Paper we describe briefing how we have tackled the problem. (A more detailed analysis can be found in the Appendix.) In Part II we report and comment upon the errors in our forecasts of annual growth rates and show how our forecasting performance has improved over the years. In Part III we focus on quarterly forecasts up to 8 quarters ahead, and compare our forecasting errors with measurement errors in the oficial statistics; with the estimation errors built into our forecast equations; and with the stochastic model errors we reported last February. A brief summary of the main conclusions is given below. 相似文献