城市大气环境系统污染综合防治研究

本文论述了利用大气扩散模型和数学规划模型建立反映城市布局、耗能结构和大气环境质量间制约关系的大气环境、能源、经济规划模型,并以天津市区为例讨论了大气环境污染综合防治方案。     

中国出口家电反向物流网络及其优化研究

文章分析了反向物流网络的特征、分类以及影响废旧家电回收反向物流构建的因素及构建原则;运用博弈论知识论证了进行废旧家电反向物流的必然性,在此基础上构建了废旧家电反向物流网络,运用混合整数线性规划模型对其进行优化.最后,本文运用例子证明了混合整数线性规划及其算法-分枝定界法的实用性和有效性.     

Spatio-temporal patterns in county-level incidence and reporting of Lyme disease in the northeastern United States, 1990–2000

We present an exploratory analysis of reported county-specific incidence of Lyme disease in the northeastern United States for the years 1990–2000. We briefly review the disease ecology of Lyme disease and the use of risk maps to describe local incidence as estimates of local risk of disease. We place the relevant elements of local environmental and ecological variables, local disease incidence, and (importantly) local disease reporting in a conceptual context to frame our analysis. We then apply hierarchical linear models of increasing complexity to summarize observed patterns in reported incidence, borrowing information across counties to improve local precision. We find areas of increasing incidence in the central northeastern Atlantic coast counties, increasing incidence branching to the north and west, and an area of fairly stable and slightly decreasing reported incidence in western New York.     

Finding all optimal solutions to the reserve site selection problem: formulation and computational analysis

The problem of selecting nature reserves has received increased attention in the literature during the past decade, and a variety of approaches have been promoted for selecting those sites to include in a reserve network. One set of techniques employs heuristic algorithms and thus provides possibly sub-optimal solutions. Another set of models and accompanying algorithms uses an integer programming formulation of the problem, resulting in an optimization problem known as the Maximal Covering Problem, or MCP. Solution of the MCP provides an optimal solution to the reserve site selection problem, and while various algorithms can be employed for solving the MCP they all suffer from the disadvantage of providing a single optimal solution dictating the selection of areas for conservation. In order to provide complete information to decision makers, the determination of all alternate optimal solutions is necessary. This paper explores two procedures for finding all such solutions. We describe the formulation and motivation of each method. A computational analysis on a data set describing native terrestrial vertebrates in the state of Oregon illustrates the effectiveness of each approach.     

北京城近郊区园林绿地多目标规划

北京市城近郊区人口密集,经济活动频繁,作为改善城市空气质量的重要环境资源之一,园林绿地提供了不可或缺的生态服务功能。针对研究区降尘大、SO_2浓度高以及生产生活耗氧量大等主要环境问题,以满足城市居民环境质量基本要求为目标,通过一系列决策变量与约束条件的设定,建立起北京城近郊区园林绿地多目标线性规划模型。应用Lingo 8．0软件对规划模型求解,结果表明,规划期(2020年)不同种类园林绿地面积分配较基期(2000年)更为合理,强调通过乔灌草相结合提高园林绿地整体生态服务功能,为北京建设生态城市提供了规划依据。     

Space-time modeling for the Missouri Turkey Hunting Survey

The Missouri Turkey Hunting Survey (MTHS) is a postseason mail survey conducted by the Missouri Department of Conservation. The 1996 MTHS provides information concerning the number of turkeys harvested by hunters on each day and the total number of trips made to the counties by these hunters on each day of the hunting season. The success rates are then found from this information. Small sample sizes produce large standard errors for the estimates at the county level. We use a Bayesian hierarchical generalized linear model to estimate daily hunting success rates at the county level. The model includes an autoregressive process for the days of the hunting season and spatially correlated random geographic effects. The computations are performed using Gibbs sampling and adaptive rejection sampling techniques. Results show that there are significant spatial corelations between counties and correlations between days of the hunting season. The estimates are close to the frequency estimates at the state level and much more stable at the county level.     

Empirical Bayes calculations of concordance between endpoints in environmental toxicity experiments

Hierarchical models are considered for estimating the probability of agreement between two outcomes or endpoints from an environmental toxicity experiment. Emphasis is placed on generalized regression models, under which the prior mean is related to a linear combination of explanatory variables via a monotone function. This function defines the scale over which the systematic effects are modelled as additive. Specific illustration is provided for the logistic link function. The hierarchical model employs a conjugate beta prior that leads to parametric empirical Bayes estimators of the individual agreement parameters. An example from environmental carcinogenesis illustrates the methods, with motivation derived from estimation of the concordance between two species carcinogenicity outcomes. Based on a large database of carcinogenicity studies, the inter-species concordance is seen to be reasonably informative, i.e. in the range 67–84%. Stratification into pertinent potency-related sub-groups via the logistic model is seen to improve concordance estimation: for environmental stimuli at the extremes of the potency spectrum, concordance can reach well above 90%.     

Quadratic diversity: Its maximization can reduce the richness of species

In recent decades numerous diversity indices have been introduced. Among them the quadratic entropy index Q expresses the mean difference between two individuals chosen from the community at random. Differing from diversity indices habitually employed, Q does not satisfy a property postulated earlier for those measures. Namely, the uniform distribution of species does not necessarily yield the maximal index value. Q is based on the difference matrix of species. For a given matrix one can seek for the vector yielding the maximum quadratic entropy. This task leads to a quadratic programming problem. Using the appropriate program of a program package, we determined the maximum vector for a genetic difference matrix of crane species, as published in the literature. We discovered that some components (frequencies) in the maximum vector are equal to zero. That is, by maximizing the quadratic diversity some species can be eliminated. We discuss briefly the possible implications of this observation. Moreover, even if all elements in the maximum vector are positive, the elements can differ.     

Energetic state and the performance of dawn chorus in silvereyes (Zosterops lateralis)

Stochastic dynamic programming (SDP) models predict that males singing to attract a mate should concentrate singing in what has been termed the dawn chorus. This is because male birds should have a variable surplus of fat in the morning that can be used to fuel singing, with the amount of fat available dependent upon such factors as his quality, foraging success and risk of predation. In this manner, the dawn chorus can act as an indicator of male quality in the context of female mate choice. We test a key prediction of SDP models of singing behaviour that males with greater fat levels should sing more. We conducted an experiment where we recorded the dawn chorus of male silvereyes (Zosterops lateralis) on three consecutive days. Each male received supplementary food on the second day, which enabled us to sample his dawn chorus before, during and after food supplementation. We also collected data on the effect of supplementary food on the body mass of silvereyes. As predicted by SDP models, we found that silvereyes sang for a greater proportion of the time after receiving supplementary food. Supplementary food also had a significant effect on the complexity of a male song, indicating that males not only increased the quantity of their song but also the quality of their song when they received extra food. As the provision of supplementary food significantly increased the mass of fed birds, our results support a causal link between male energy reserves and his ability to perform the dawn chorus.     

板料冲压成形和回弹分析过程的三维动态模拟

利用ANSYS/LS DYNA非线性动力有限元程序的显式 隐式连续求解功能 ,模拟了板料成形过程与卸载后板料回弹变形的全过程 ,得到了成形过程中任一时刻各处的应力和应变值及卸载后板料的回弹结果