COMPARISON OF STOCHASTIC AND DETERMINISTIC DYNAMIC PROGRAMMING FOR RESERVOIR OPERATING RULE GENERATION1

ABSTRACT: Two dynamic programming models — one deterministic and one stochastic — that may be used to generate reservoir operating rules are compared. The deterministic model (DPR) consists of an algorithm that cycles through three components: a dynamic program, a regression analysis, and a simulation. In this model, the correlation between the general operating rules, defined by the regression analysis and evaluated in the simulation, and the optimal deterministic operation defined by the dynamic program is increased through an iterative process. The stochastic dynamic program (SDP) describes streamflows with a discrete lag-one Markov process. To test the usefulness of both models in generating reservoir operating rules, real-time reservoir operation simulation models are constructed for three hydrologically different sites. The rules generated by DPR and SDP are then applied in the operation simulation model and their performance is evaluated. For the test cases, the DPR generated rules are more effective in the operation of medium to very large reservoirs and the SDP generated rules are more effective for the operation of small reservoirs.     

混凝土简支梁设计基准期内的可靠度

根据统计资料对不同类型建筑在不同防火措施下发生火灾的概率研究,得出了各类建筑达到轰燃的概率.基于蒙特卡罗随机有限元方法,引入材料高温本构关系、截面尺寸和计算模型系数等的变异性,按照ISO标准升温曲线升温,给出了单构件轰燃下的失效概率计算方法.最后,将设计基准期内建筑物达到轰燃的概率与单构件轰燃下的失效概率组合,给出了设计基准期内建筑构件在火灾下的失效概率公式.     

Integration of ecological–biological thresholds in conservation decision making

In the Anthropocene, coupled human and natural systems dominate and only a few natural systems remain relatively unaffected by human influence. On the one hand, conservation criteria based on areas of minimal human impact are not relevant to much of the biosphere. On the other hand, conservation criteria based on economic factors are problematic with respect to their ability to arrive at operational indicators of well‐being that can be applied in practice over multiple generations. Coupled human and natural systems are subject to economic development which, under current management structures, tends to affect natural systems and cross planetary boundaries. Hence, designing and applying conservation criteria applicable in real‐world systems where human and natural systems need to interact and sustainably coexist is essential. By recognizing the criticality of satisfying basic needs as well as the great uncertainty over the needs and preferences of future generations, we sought to incorporate conservation criteria based on minimal human impact into economic evaluation. These criteria require the conservation of environmental conditions such that the opportunity for intergenerational welfare optimization is maintained. Toward this end, we propose the integration of ecological–biological thresholds into decision making and use as an example the planetary‐boundaries approach. Both conservation scientists and economists must be involved in defining operational ecological–biological thresholds that can be incorporated into economic thinking and reflect the objectives of conservation, sustainability, and intergenerational welfare optimization.     

SOME PROBLEMS IN STOCHASTIC HYDROLOGY1

In order to decrease the uncertainty that results in water resource planning and management studies due to the assumed recurrence of historical hydrological sequences, considerable study of stochastic processes in hydrology has taken place during the past 10 or 15 years. The general objective has been to develop a capability for generating a number of valid sequences, each of which could as resonably occur as could a recurrence of past events. A number of serious problems have been encountered, the consequence of which has been a serious lag in the application of stochastic processes to real planning and management problems. These problems include: a. an inability to generate droughts in some cases that are as extreme as have occurred historically, b. the generation of inconsistent values of stream flow at 2 locations on the same stream, c. the lack of mathematical techniques for the management of incomplete data sets, d. a great increase in the required computation for planning and management studies, and e. theoretical and computational difficulties in expanding the scope of stochastic hydrology from monthly quantities to short-period quantities. This paper discusses these problems and various approaches used in attempting their solution.     

OPTIMAL RESERVOIR MANAGEMENT AND CROP PLANNING UNDER DETERMINISTIC AND STOCHASTIC INFLOWS1

ABSTRACT: This study analyzes planning under deterministic and stochastic inflows for the Mayurakshi project in India. Models are developed to indicate the optimal storage of reservoir water, the transfer of water to the producing regions, and the spillage of water from the reservoir, if needed. A deterministic programming model was first formulated to represent the existing situation. A chance-constrained model then was constructed to evaluate potential violations of the deterministic model. Both models were quantified for the command area. Data were collected from surveys of the area and from government agencies. Both the deterministic and change-constrained models suggest a more intensive cropping program in the region. Both emphasize more dependence on rabi and less on kharif crops. The chance-constrained especially suggests use of more water in the rabi season. Important chances in cropping programs and labor use take place under the chance-constrained model.     

STOCHASTIC MODELING OF MONTHLY AND DAILY RAINFALL SEQUENCES1

ABSTRACT: A monthly model and two daily models (I and II) are presented for the purpose of generating monthly and daily rainfall sequences in the Quae Yai river basin in Thailand. Performance of the models are evaluated by comparing the statistical parameters of the generated sequences with those from historical data. For monthly generation, Thomas-Fiering model worked satisfactorily in spite of the monthly correlations being weak, if any. Daily Model I, which assumes no persistence between daily rainfall amounts within the wet spells, could not preserve some important parameters regardless of the simplicity in model construction. Application of multi-state transition probability matrix model gave good results, although the user has to modify some parameters looking at the performance of the model for each historical record.     

基于随机前沿的天津市碳排放效率分析

运用随机前沿分析(SFA)的方法,从土地、资本和劳动中提取城市化率、人均道路面积、人均绿地面积、绿化覆盖率、R&D经费投入强度、环保投资指数、从业人员占总人口比重7个相对量指标作为投入要素,将单位碳排GDP产出作为产出要素,计算和分析了我国30个省域2006年和2011年的碳排放效率,并分析天津市在全部样本的碳效率水平。结果显示:天津市碳排放效率分别居于30个省域的第5位和第3位,属于碳排放效率高的省域。     

基于随机模拟的地下水污染物最优水力截获量

水力截获技术是净化或抑制地下水污染最为广泛使用的一种方法，而该技术实施过程中，如何确定最优水力截获量是其需要重点解决的关键问题.本文针对传统确定性方法计算最优水力截获量不合理的问题，从水文地质参数的随机性出发，应用基于随机理论的蒙特卡罗方法，通过实例来研究渗透系数的空间变异性对地下水污染物水力截获系统的影响，并寻求估算最优水力截获量的新方法.通过研究表明：基于确定性方法计算出最优水力截获量为110m³/d时恰好能完全截获污染区的污染物；应用随机模拟研究含水层渗透系数的空间变异性对水力截获系统的影响，发现当以传统确定性方法所计算的最优水力截获量（110m³/d）抽水时，并不能总是完全截获地下水污染物，其面临的稳定平均风险率高达24%；充分考虑了含水层渗透系数空间变异的Monte Carlo方法较以往传统确定性方法更为可靠，为此本文提出利用随机方法从截获系统可接受风险角度确定最优截获量的新思路.     

地铁运营突发事件应急响应模式的马尔科夫链分析

为研究城市轨道交通网络化运营线路的风险传导规律和耦合关系,构建基于随机Petri网的同构马尔科夫链模型。通过模型分析突发事件应急响应模式中线路之间的相互影响,以及各线路启动突发事件应急响应模式对整个系统稳态的影响。结果表明,用该模型可从数学上研究城市轨道交通运营线路之间的传导规律和耦合关系,找出影响整个应急指挥系统效率的关键因素,最终提高地铁应对突发事件的能力。