Bolt support mechanism based on elastic theory

Mechanical model of anchorage surrounding rock considering tray effect was established based on elastic theory, in order to study the mechanism of bolt supporting. Elastic solutions of normal force at point in the interior of a semi-infinite solid were obtained by means of classical displacement function method in elasticity. The factors which influence stress of bolted surrounding rock, such as the length of bolt and tray effect, were analyzed. The absolute value of stress along bolt axes decreased rapidly with an increase in radical distance and the maximum appeared near ends of bolt. With increasing radical distance, the value of radical stress changed from positive to negative roughly and then increased to zero, with maximum at the middle of bolt. The evolution of hoop stress as radical distance increasing was similar with stress along bolt axes. With an increase in depth, the radical effect ranges of all normal stress components were reduced. These suggest that the effect from tray on stress along bolt axes of bolted surrounding rock could be neglected, except near surface of surrounding rock.     

平板闸门垂向自激振动数学模型研究

在分析前人实验结论和平板闸门自激振动机理的基础上,将结构—尾流振子模型应用到闸门垂向自激振动的研究中,振子模型采用von der por方程,在结构的控制方程中合理地加入了附加质量项。通过确定模型其他参数并对模型进行计算得到闸门稳定自激振动（共振区）下的垂向振动峰值和频率比。计算值和实测值能较好地吻合,从而实现了影响闸门自激振动参数的整合及对闸门自激振动的定量研究,为进一步深入分析闸门自激振动的机理提供了更加可靠的依据。     

Reservoir Operation Optimization: A Nonstructural Solution for Control of Seepage from Lar Reservoir in Iran

Abstract

In this paper, the results of utilizing a deterministic dynamic programming model for operation of Lar Reservoir in Iran are discussed. This reservoir has experienced extensive seepage from the start of its operation. The optimization model consists of a three-step cycle, which began with the optimization of reservoir operation for a given set of streamflows. The optimal policies are then analyzed in a regression procedure to obtain a set of operating rules. After the first run, operating rules from the previous run were placed as a new constraint on the water releases with some pre-assigned tolerance and the cycle continues. The model also consisted of mathematical functions for modeling the seepage from Lar Reservoir as a function of storage head in the reservoir. The loss function in the model was also modified in order to incorporate parameters that reduce the seepage. Results of different scenarios showed the significant effect of optimal policies on reduction of seepage and increasing the reliability of water supply to Tehran Metropolitan Area. A pumping station was also proposed to utilize the inactive part of the reservoir, in access of over 100 MCM, in order to reduce the seepage. The effectiveness of different pumping capacities to reduce the seepage was also investigated.     

Water productivity and water footprint: misguided concepts or useful tools in water management and policy?

Water productivity (WP) and water footprint (WFP) are popular concepts in research and discourses on water management. Yet there are concerns about their theoretical validity and practical value. This paper shows that the water production function, the concept with a sound theoretical foundation, is the basis for WP. Total WFP is the reciprocal of WP. The practical value of WP and WFP depends on the context of water use and stress. Maximizing WP, not a panacea to all water problems, mainly suits arid rainfed areas. In other regions, economic and marginal WP for increasing overall production should take precedence in water management and policy decisions.     

水的生态服务功能内涵与 评价方法初探

从水的生态服务功能的机理出发,深入剖析了其内涵与水的两层次生态服务结构,并在此基础上构建评价水的生态服务功能的指标体系,介绍了评价流域水的生态服务功能的主要方法;最后提出了维系流域水的生态服务功能主要思路与手段,为水的生态服务功能研究提供了新思路与新方法。     

“500”供水闸联动稳控系统应用分析

本文介绍了＂500＂水库供水闸联动稳控及水务综合管理系统的设计原则、结构功能、智能控制、运行管理的情况,以为其他供水项目的自动化系统建设提供参考。     

基于单纯形微粒群优化算法Jensen模型参数求解

提出了基于单纯形微粒群优化算法（SMPSO）直接求解作物水分生产函数Jensen模型参数的方法。通过计算分析,用传统方法计算而得Jensen模型的相对产量与实际相对产量的相关指数为0．825,而用SMPSO（PSO）计算而得的相关指数为0．932;SMPSO寻优仅需要0．3973s,而PSO需要1．0783s。     

时滞倒立摆的H_∞反馈控制

由于系统的输入滞后不可避免,时滞是影响系统稳定性的因素之一,文中研究具有输入时滞的一级直线倒立摆的H∞控制问题.基于Lyapunov稳定性理论,采用线性矩阵不等式方法得出系统的H∞反馈控制器.文中没有引入自由权矩阵,减小了问题的复杂性.同时考虑系统不确定性.结论可由MATLAB软件直接求解,方便易行.仿真结果证实了方法的有效性.     

一类非线性分形插值曲面的构造与性质

讨论了二元连续函数振幅与变差的性质,并构造了一类非线性多参数迭代函数系;证明了在一定条件下吸引子的唯一性和分形插值曲面的存在性,利用连续函数变差的性质研究了所构造的分形插值曲面的维数,并给出了此类分形插值曲面计盒维数的计算公式.