桃林口水库降水径流变化特征分析

受气候条件变化及人类活动的影响,近年来桃林口水库降水径流特征发生了显著变化。根据Mann-Kendall检验法对流域内典型测站降水径流的时空变化特征进行分析,结果表明,桃林口水库降水过程具有显著的下降趋势,且降水中心有向中上游流域转移的趋势;加之进入20世纪70年代以来,人类活动的加剧,导致入库水资源量显著减少。     

肯尼亚工业发展及合作前景

肯尼亚是自然条件和地理位置优越的东非国家。独立后,历届政府为促进本国工业在薄弱的基础上快速发展,均作出过积极的尝试,取得了长足的进步,但仍存在轻重工业发展不平衡、长期外贸逆差、劳动力素质较低等问题。肯尼亚政府新近出台了一系列深化工业改革的政策,中国企业应该充分利用肯尼亚的政策机遇,在肯政府允许的资源开发、技术和设备引进等诸多领域,积极开展全方位、多层次的合作,加强优势互补,双边合作共赢的前景一定十分可期。     

To use or not to use? Social media in higher education in developing countries

This research is a response to the universal use of social media by students for academic-related purposes. It bridges a gap in knowledge in relation to the value and use of social media as effective teaching and learning tool in higher education in developing countries. A pre-tested questionnaire survey was self-administered to faculty members in the eight public Egyptian higher institutions offering tourism and hotel management programs. The results showed that social media have a great value for academic-related purposes, particularly as teaching and learning tool; however, the actual use by faculty was at a minimal level. In-depth interviews were conducted to identify the perils, barriers and concerns for the minimal use. Several barriers were identified with some specific to developing countries' context. Nonetheless, there was consensus by faculty that if these barriers were overcome, social media could be developed as an innovative and effective tool for teaching and learning. Implications for researchers and policy makers are discussed.     

南水北调工程地下箱涵结构地震反应分析

以南水北调工程具体实例为研究对象,通过ANSYS建立二维有限元模型对地下箱涵结构进行地震作用下的动力有限元分析,为结构设计提供了参考。     

制动摩擦材料研究进展

制动摩擦材料利用运动表面相接触时所产生的摩擦阻力达到减速或终止运动目的,是运载机械中安全保障装置的重要组成部分。本文综述了半金属基、金属基及非金属基制动摩擦材料的研究现状及优缺点,介绍了熔铸法、粉末冶金法及三维编织法等制动摩擦材料制备方法,并从摩擦、磨损、热稳定性等方面分析了制动摩擦材料的关键特性。从研究状况可知,摩擦材料正向少纤维、无纤维型方向发展,高性能、环保型摩擦材料具有较大的发展优势。优化制备工艺、降低生产成本、提高性能、扩大应用领域将是未来制动摩擦材料的研究重点。     

基于数据挖掘的火电厂最经济煤种决策方法

在分析煤质变化对火电厂运营成本影响的基础上,提出了综合评价发电企业的复合燃煤使用成本计算模型.基于数值型模糊关联规则数据挖掘方法,确定了煤质特性与发电企业的燃煤装卸倒运成本、污染物排放成本、原煤采购成本、脱硫系统运行成本、辅机耗电成本及设备维护成本的关联关系,提出了一种基于数据挖掘技术的最经济煤种决策方法.以某电厂3年历史运行数据为基础,对4种预采购煤种的复合燃煤使用成本进行了比较分析,在高价优质煤与低价劣质煤之间确定了最经济煤种.结果表明：燃煤采购决策既需要考虑发电企业生产过程的多个环节,也需要考虑燃煤价格因素及燃煤的煤质因素.燃用便宜的劣质煤不一定比燃用价格较高的优质煤更合算,一味追求高品质的高价煤或低价格的劣质煤都是不可取的,煤种2为该厂的最经济煤种.     

SWAT模型在丘陵地区的非点源污染模拟研究

采用SWAT模型对苏南丘陵研究区进行非点源负荷模拟,对模型进行了率定、验证,在此基础上分析非点源污染与降雨径流的时间特性;比较不同土地利用情景下非点源污染负荷的变化;研究施肥对非点源污染负荷的影响;探讨不同管理措施对非点源污染的影响;为该区域非点源污染控制和综合治理提供科学依据。     

Study on the optimal hydropower generation of Zhelin reservoir

Zhelin reservoir, a multi-purpose reservoir designed mainly for hydropower generation, is located in Xiushui watershed in Jiangxi Province, China. As the rainfall has a decreasing trend in recent years, the reservoir storage capacity cannot be fully filled and the original operation rule can no longer fulfill the desired target for power production. In order to ensure the dam safety and produce more economic benefits from hydropower generation, the original operation rule of the reservoir needs to be evaluated for possible improvement to yield optimal benefits. In this study three optimization algorithms including progressive optimization algorithm (POA), particle swarm optimization (PSO) and genetic algorithm (GA) are applied. According to a long discharge data series, the minimization of water consumption rate is chosen as the objective function, along with several physical and operational constraints. After comparing the results of the three methods, POA is found more suitable for Zhelin reservoir. Sensitivity of the optimization algorithms is also analyzed, of which, the step size of water level of the reservoir for POA, the initial population sizes for PSO and GA are also explored to search for the most suitable parameters. The investigation further reveals that step size 0.01 m, population size 50 and 30 are the best choice for POA, PSO and GA, respectively.     

基于Web的教学流媒体视频点播系统

介绍了ASP技术和流媒体技术的相关知识以及Helix Server服务器的特点,阐述了在Windows平台上设计和实现教学视频点播系统的思路和方案,并指出了开发的重点和难点.本文还涉及到了ASP中相关组件的使用,数据库的设计和Helix Server服务器的安装配置.     

基于实景三维GIS的水库移动巡查系统设计

根据地理信息系统在国内外的实际应用情况,提出了开展基于实景三维GIS水库移动巡查系统研究的必要性,并分析系统目标和设计原则,进而从总体架构、功能模块、系统特点等方面进行研究,阐述利用实景三维GIS、移动GIS、GPS、移动通信、数据交换等技术建设水库移动巡查系统的设计方案,该设计可作为水库移动巡查技术架构的基础,具有一定的实用价值.