首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 125 毫秒
1.
基于钱塘江河口段水质污染的系统分析,建立了水质污染评价指标体系,利用灰色关联理论构建了水质污染评价数学模型,提出了5级-6区间指标归一化方法,使得超标水质的影响能得到真实反映.根据水质实测数据,对该河段水质状况做出了综合评价,提出了防治污染,改善水质状况的对策.  相似文献   

2.
依据动量定理、电荷守恒定律建立了弹性波在压电固体中传播的数学模型.不仅考虑了压电效应,也同时考虑了电流效应.在压电固体中同时存在机械位移场、极化电势场和电流场.求解波动方程,发现不考虑电流效应时,弹性波是非色散的;考虑电流效应后,弹性波是色散的.不仅如此,电流效应还导致弹性波的衰减.通过数值模拟,揭示了平衡载流子浓度对色散和衰减的影响规律.  相似文献   

3.
从心理学、第二语言习得理论出发,研究了场独立与场依存认知风格的外语学习者特点,应用因子分析数学模型,进行了培养元认知策略意识及发展双重认知风格等教学策略的教学实验,仿真实验表明了该方法的实用性和有效性.  相似文献   

4.
根据化学动力学理论,由化学反应速率的定义,利用机理分析法以及反应速率微分方程,对化学反应的生成物浓度与时间、温度的关系进行了定性、定量分析.根据不同的反应条件,深入研究并建立及推广了生成物浓度数学模型.经实验检验,建立的数学模型具有高度的概括性、准确性,可应用于预测、控制化学反应系统、优化工艺过程.  相似文献   

5.
首先以二维水动力弥散实验为基础 ,根据实验所提供的信息 ,建立了二维水动力弥散实验的随机水质数学模型 .其次我们对所建模型进行了数值模拟计算 ,计算结果与实测数据比较吻合 ,从而说明所建立的随机模型是合理的 ,有实际应用价值 .  相似文献   

6.
在一维扩散模型的基础上,建立了放射性核素在水质中的瞬态三维扩散模型,并给出了瞬态排放模式下模型的计算公式,实现了水质中放射性核素扩散浓度的快速估算.在MATLAB程序下,利用该方法对一个实例进行了仿真分析,得出相关结论,对于核泄漏事故下放射性核素扩散浓度预测评估及制定安全措施具有指导意义.  相似文献   

7.
竞争力研究的新视角:动力学理论分析框架   总被引:1,自引:0,他引:1  
突破基于指标体系评估的静态分析模式,提出了竞争力研究的新视角,建立动力学理论分析框架.提出了竞争力场模型,包括竞争强度、竞争势、要素密度、要素极化等定义及其表达方式,并创建竞争场能、竞争场信息熵的概念和数学模型.给出了竞争场的高斯定理与环路定理,并证明了竞争场信息熵的凸性定理及其极大熵原理.最后指出了竞争力的动力学理论研究的进一步发展方向.  相似文献   

8.
王涛  段俐 《应用数学和力学》2006,27(9):1029-1035
运用光学干涉诊断方法实时观测NaClO3晶体生长过程,得到晶体生长过程中溶液浓度,晶体尺寸等物理参量.将这些参量与数值模拟得到的结果进行比对,研究重力条件下NaClO3晶体溶液生长过程中速度场、浓度场的分布与演化,尝试提出符合实际情况的晶体生长理论模型,对比两种方法得到的浓度边界层厚度,数值模拟得到了与实验数据相一致的结论.  相似文献   

9.
<正> 一、引言水质规划是水资源保护工作的主要内容之一,是围绕总量控制规划发展起来的一门新兴学科.本文是在水网区域探讨一类具有非稳态水流水质规划的数学模型及求解方法.其方法直观、简单,便于应用.  相似文献   

10.
对管材无模扩径变形速度场及壁厚变化规律进行了理论及实验研究.分析了管材无模扩径的变形模型、速度场以及壁厚变化的影响因素及影响规律,采用上限法确定了管材无模扩径速度场及壁厚变化数学模型.  相似文献   

11.
工业化发展导致了脆弱的土地进一步沙漠化,沙漠地区政府应综合考虑经济发展与土地沙漠化导致的生态质量降低。通过构建两个沙漠化地区微分博弈模型,研究了两个地区的沙漠治理问题。研究结果表明,提高工业生产排放技术或沙漠治理技术均能够提高均衡经济产出水平,在工业生产收益系数较高的情况下也能够提高沙漠治理投入水平,并且两种技术提高存在交互效应;只有对生产排放技术水平和沙漠治理技术水平较高的地区,延长地方政府领导任期有利于沙漠治理;实现沙漠完全治理情况下控制土地再沙化的治理投入低于控制沙漠稳定在一定规模的治理投入。  相似文献   

12.
The Raipur and Indravati series comprising the Purana formations of Chhattisgarh consist of conglomerates, orthoquartzites, sub-arkoses, shales, limestones and dolomites. The lithofacies in these have considerable lateral variations. Both Mahanadi and Indravati basins are saucer-shaped with centripetal dips; the arenaceous rocks along the fringes have dips up to 15°, while the younger rocks in the centre are almost horizontal. In carbonate rocks, karst is developed on a regional scale with sinkholes of higher topographic areas linked with resurgences of low relief areas. Groundwater in the above formations occurs generally under water table condition, but in karstic limestone also under confined condition. The chemical relationship of groundwater circulating in the various lithofacies are plotted in the trilinear diagrams after Piper. Groundwater within depths of 92m has carbonate hardness (Secondary alkalinity) exceeding 50 per cent with the chemical properties dominated by alkaline earths and weak acids. The cations and anions in water from similar lithofacies of Mahanadi and Indravati basins are distributed in the same field of the trilinear diagram with almost similar scatter of ions suggesting thereby a similar geochemical environment. The quality of groundwater is within permissible limits for irrigation and domestic purposes, while softening of water from temporary bicarbonate hardness may be necessary for certain specific industries. Expansion of groundwater recharge by increasing the ‘area of spreading’ of flood water of the Mahanadi basin and application of the technique in the Indravati basin will enrich the soils. Prevention of disposal of industrial wastes underground, especially in karstic regions will be a primary step in pollution control.  相似文献   

13.
考虑到干旱、半干旱地区的幼年植被与成年植被之间存在竞争水资源的现象,该文构建一个具有种内竞争时滞的植被-土壤水动力学模型。分析出系统存在植被灭绝平衡点和植被生存平衡点,并给出了平衡点局部稳定的条件,分别给出非空间系统和空间系统产生Hopf分支周期解的条件。通过数值模拟展示出两种系统对应的植被随时间演化做周期振荡模式,并通过参数敏感性分析发现降雨量和植被的增长率对这种模式的产生和模式的振幅、周期有显著影响,但蒸发量的影响效果最不显著,表明降雨量和植被本身的特征对干旱、半干旱地区植被的演化发展产生了深刻的影响。同时发现空间扩散的引入会抑制这种模式的发生,但对振幅和周期没有任何影响。所获得的结果解释了自然界中广泛观察到的植被周期振荡现象,为植被系统的可持续发展提供了理论支撑。  相似文献   

14.
The rapid agricultural development of the Yellow River basin in China has caused serious potential water pollution to the vicinal areas. In this paper, a compact scheme is developed and employed to simulate the unsteady transportation of three representative water quality variables including ammonia nitrogen, nitrite nitrogen and nitrate nitrogen in the downstream Yellow River. As an extension of Ref. [Yang ZF, Chen GQ. The compact fourth-order finite difference scheme for the unsteady convection–diffusion equation involving source term. Chin Sci Bull 1993;38(2):113–6 [in Chinese]], the scheme is applied to the more general convection–diffusion equation with complicated terms reflecting the mutual action of water and sediment, which conforms to the characteristic of high sediment concentration of the Yellow River. The simulation results indicate that the error yielded from the proposed method is smaller than that of the referenced scheme (five-point hybrid scheme) in solving the water quality equation.  相似文献   

15.
Due to the hot, arid nature of its bordering lands, seawater in the Arabian Gulf can have significant evaporation rates leading to hypersaline conditions. If additional desalination plants were to operate along its coast, then the extraction of desalinated water and returned brine waste stream into the Gulf would increase the salinity. This paper uses a tidally and cross-sectionally averaged mathematical model that reveals multiplicative dependence of the salinity on factors associated with river flow, evaporation rates and each of the desalination plants. Present-day desalinated water production rates are in the linear regime, but hypersalinity has exponential sensitivity to the position and volumetric rate of desalinated water extraction.  相似文献   

16.
流域水资源分配纳什均衡实现过程的进化博弈分析   总被引:5,自引:1,他引:4  
由于有限理性,流域不同地区在水资源数量与质量分配上就不像完全理性情况下分析的那样,一开始就能找到最好的对策来直接实现纳什均衡。本运用进化博弈理论,说明有限理性的流域不同地区能够通过不断地学习、协调,逐步地提高自己的理性程度并相应地调整对策,来达到一个具有一致性的水资源数量与质量分配的纳什均衡。本的结论可为流域管理机构制定相应的水资源管理政策提供理论依据。  相似文献   

17.
干旱地区陆面过程耦合模式及应用   总被引:2,自引:0,他引:2  
本文主要论述干旱地区陆面过程在改善人类生存环境与研究区域经济中的重要地位与研究现状,强调了采用耦合模式的必要性,详细描述了该模式的特点,并将它应用于我国西北腾格里沙漠南缘植物固沙区的水热循环研究,揭示干旱区陆面过程的主要特征,并同现场测试进行了比较。  相似文献   

18.
A classic problem in elementary cellular automata (ECAs) is the specification of numerical tools to represent and study their dynamical behaviour. Mean field theory and basins of attraction have been commonly used; however, although the first case gives the long term estimation of density, frequently it does not show an adequate approximation for the step-by-step temporal behaviour; mainly for non-trivial behaviour. In the second case, basins of attraction display a complete representation of the evolution of an ECA, but they are limited up to configurations of 32 cells; and for the same ECA, one can obtain tens of basins to analyse. This paper is devoted to represent the dynamics of density in ECAs for hundreds of cells using only two surfaces calculated by the nearest-neighbour interpolation. A diversity of surfaces emerges in this analysis. Consequently, we propose a surface and histogram based classification for periodic, chaotic and complex ECA.  相似文献   

19.
The paper attempts to evaluate the permeability data obtained from 75 aquifer performance tests conducted on open wells tapping the water table aquifer of the basaltic lava flows spread over the three different basins of Maharashtra. The permeability has been computed by Thiem’s formula and the modified Theis non-equilibrium formula. The statistical analysis of the permeability data of the study basins,viz., Bhima, Godavari and Wardha, reveal a decrease in permeability range as one proceeds from the Bhima basin (low rainfall area) through the Godavari basin (assured rainfall area) to the high rainfall area of Wardha basin. The permeability frequency graphs of the three study basins reveal different hydrogeological characteristics for each.  相似文献   

20.
In this paper time-dependent water motions generated by seismic-type horizontal excitation in shallow basins and channels are modelled by the two-dimensional depth-averaged shallow water equations in which a specific source term is added in order to include an earthquake-induced forcing effect. Sinusoidal excitation is considered as a first approximation, and the response of shallow basins and channels to this simple external forcing is characterized. The nondimensional form of the governing equations shows that the Strouhal number and a ratio representing the amplitude of the forcing acceleration are the influential dimensionless parameters. Novel exact solutions of sinusoidally-forced smooth waves in a prismatic tank, a rectangular open channel, and a parabolic basin are presented. In the first two cases, a sway motion occurs, and reflections take place at the side walls. In the last case, the water sloshes back and forth flowing up the sloping sides of the basin; the free surface remains planar and a moving circular shoreline is present. These analytical solutions provide useful standards for assessing the accuracy of the numerical models used to solve the two-dimensional shallow water equations with source terms.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号