面向多区域防洪的长江上游水库群协同调度模型

长江上游水库群是长江流域防洪工程体系的重要组成部分,承担着水库所在河流、川渝河段以及长江中下游的防洪任务。长江流域面积广大,水系众多,洪水地区组成与遭遇十分复杂,防洪需求众多,防洪对象分散,且要兼顾发电、航运、供水、生态、库区安全等多种因素,水库群防洪调度面临大规模、多区域、多层次等协同调度技术难题。以长江上游25座控制性水库为研究对象,基于防洪格局和防洪任务将水库群防洪调度划分为核心、骨干和群组水库,阐明了水库群多区域协调防洪的调度节点和角色定位,提出了兼顾"时-空-量-序-效"多维属性的模型功能结构,构建了长江上游水库群多区域协同防洪调度模型,并在长江流域防洪调度形成示范应用,以挖掘长江上游水库群防洪调度潜力,进而提升长江流域防洪调度管理水平。     

大型复杂跨流域调水工程电站-水库-泵站群多目标优化调度

考虑调水量、发电最大和耗能最小3个目标,建立电站-水库-泵站群多目标优化调度模型。基于参数调整策略、邻域变异和加速策略,提出了求解多目标优化调度模型的综合改进布谷鸟新算法并求解模型,获得了发电、调水、泵站耗能多目标Pareto解集。以引汉济渭大型复杂跨流域调水工程为实例,将该模型与模拟调度模型和NSGA-Ⅱ算法多目标优化调度模型的结果进行比较,结果表明,该优化调度模型的发电、调水、耗能、弃水等各项指标合理,具有相对优势。     

洱海弥苴河河口湿地流场模拟及治理措施

洱海弥苴河河口湿地整治是洱海保护治理与流域生态建设的一项重要内容。通过数值模型方法进行模拟可对湿地现状及相应措施实施后的改善效果进行直观分析。利用二维水动力模型模拟湿地现状,提出主要存在问题和相应治理措施,并进行模型验证。验证结果表明,所选工程措施可有效治理洱海弥苴河河口湿地长期存在进水不畅等问题,有效提高河口区域生态环境水平。     

大型桁架临时固结法吊装工法

超高、超重、超长桁架吊装施工的桁架稳定性,历来受到施工单位高度重视,能否在节省费用的同时做到施工安全及线性美观,是施工企业能否做到经济、迅速、高效的关键。京能水洞沟电厂输煤系统7号栈桥工程钢桁架架空结构吊装中,采用了新的施工工法,取得了良好的效果,为相似工程的施工积累了宝贵的经验,值得在类似结构的工程施工中借鉴。     

基于LDA和word2vec的英文作文跑题检测

针对目前国内的英语作文辅助批阅系统缺少准确而高效的跑题检测算法的问题,提出了一种结合LDA和Word2vec的跑题检测算法。该算法利用LDA模型对文档建模并通过Word2vec对文档训练,利用得到的文档主题和词语之间的语义关系,对文档中各主题及其特征词计算概率加权和,最终通过设定合理阈值筛选出跑题作文。实验中通过改变文档的主题数而得到的不同F值,确定了最佳主题数。实验结果表明所提出的方法比基于向量空间模型的方法更具有效性,可以检测到更多的跑题作文并且准确率较高,F值达到89%以上,实现了作文跑题检测的智能化处理,可以有效地应用在英语作文教学中。     

兴趣度在基于关联分析的选课指导系统中的研究与应用*

简要地介绍了数据挖掘技术,通过对关联分析的经典算法Apriori在学生选课指导系统中的应用分析,发现了Apriori不适合学生选课指导系统的缺陷.提出了增加兴趣度阈值以减少产生的无用规则,提高挖掘精度,克服原系统缺陷的新算法,为学生选课辅助决策提供了良好的理论依据和实现方法.     

Large magnetic-field-induced strains in rare earth polycrystalline Ni-Mn-Ga

The magnetic-field-induced strains (MFIS) of polycrystalline Ni50Mn29Ga21 alloys containing Tb were studied. A large MFIS of-1.10% was obtained under compressive prestress conditions. The addition of Tb can fine the crystal grains, enhance the bending strength obviously, and make MFIS increase further, indicating that a moderate amount of Tb does not hinder twin boundary motion and it conversely makes the material more practical.     

高耐蚀性热镀锌板的钝化处理工艺探讨

介绍了热镀锌板钝化膜的形成机理 ;针对攀钢热镀锌板出现白锈、黑斑等问题 ,分析了钝化液pH值、添加剂及操作条件对钝化膜质量的影响 ,同时提出了改进热镀锌板耐蚀性能的措施     

(Short communication) Degradation of corrosion resistance of Zircaloy-4 in LiOH aqueous solution

To investigate the degradation of corrosion resistance of Zircaloy-4 in LiOH aqueous solution, SIMS (secondary ion mass spectrometry) analysis was performed to examine the profiles of Li~ , K~ , and OH~- in oxide layers formed in the same concentration (0.1 mol/L) LiOH and KOH solutions. Even though the oxide layers have an equal thickness, the penetration depth of K~ is shallower than that of Li~ , and the penetration depth of OH~- corroded in KOH solution is also shallower than that corroded in LiOH solution. It shows that the diffusion of OH~- into oxide layer is accompanied by the corresponding cation. The difference of degradation effect of LiOH and KOH solutions on the corrosion resistance of Zircaloy-4 was discussed.     

Global robust output tracking control for a class of cascade nonlinear systems with unknown control directions

We investigate the global robust tracking problem via output feedback for a class of cascade nonlinear systems with dynamic uncertainties and non-vanishing disturbances. It does not require a priori knowledge of the sign of the high-frequency gain. A recursive design scheme is presented using the ideas of pseudosign function, Nussbaum-type gain technique and the deadzone method. It is shown that under some conditions, the tracking error can be guaranteed asymptotic to the interval [?ε, ε]?? with arbitrary prescribed ε>0 after a finite time, while keeping all signals of the resulting closed-loop systems bounded. The simulation results demonstrate the effectiveness of the proposed algorithm.