洪涝灾害条件下疏散交通生成预测方法

为有助于有关部门更准确预测洪涝灾害受灾民众的疏散量,结合非集计数据和集计数据的优点,提出分区集计数据的概念,设计了受灾区域分区方法,并通过意向偏好(SP)调查法对我国居民在洪涝条件下疏散交通需求数据进行调查。在此基础上,引入BP神经网络建立基于分区集计数据的疏散交通生成预测模型。利用调查数据进行实证分析发现,所设计方法取得了较好的预测效果,鲁棒性较好,平均相对预测误差仅为1.8%,其预测效果明显优于现有的非集计和整集计模型。     

Water saving effect on integrated water resource management

This study proposes an improved integrated water resource management (IWRM), in which water conservation was analyzed for the entire water use process. A multi-objective optimization method was applied to optimize the IWRM, which investigated the reduction of freshwater consumption and the total water supply cost. Customer's preference for saving water and an end use analysis (EUA) was applied in the water conservation analysis. Taking Tianjin as the study area, a reduction in customer's economic pressure (EP) was utilized to evaluate the degree of the customer's preference for saving water. The results revealed that agriculture had a greater preference for saving water than other sectors, where as the public had the weakest motivation for saving water. Improving the transportation method could contribute 62.1% of the total water savings in the agriculture sector. The optimization of the IWRM demonstrated that the local freshwater savings would be 21.5%, and the total cost for water supplies would decrease by 13%. However, a government subsidy of 87.5 million Yuan would be needed. Additionally, by analyzing the change in the amount of water savings affected by water price, the appropriate water price increase range was suggested to be 1.5–1.7 times the original price.     

考虑公众选择偏好的应急避难安置双阶段选址-分配模型

为使开放避难场所符合公众自行避难的实际情况,借鉴Huff模型量化公众选择行为,构建双阶段选址-分配模型,第1阶段确定开放避难场所位置,第2阶段将溢出容量的灾民二次分配到有剩余容量的避难场所,并利用改进粒子群算法进行求解。研究结果表明：双阶段选址-分配模型能够实现同一需求点灾民前往不同避难场所的过程,管理者干预政策能够使服务人数大幅度增加,避免资源浪费、灾民流离失所且二次分配情况主要依赖于第1阶段的结果。研究结果可为管理部门规划应急避难场所提供参考。     

The Optimal Depletion of Exhaustible Resource under Different Commitment

There are few papers in the literature focusing on the issue of the optimal depletion of exhaustible resources in the framework of variable time preference. This paper attempts to analyze the pure consumption of exhaustible resource under hyperbolic time preference, and to discuss the optimal depletion rate and the effect of the protection of the exhaustible resource under different commitment abilities. The results of model show that the case of the hyperbolic discount with the full commitment of the government is equivalent to the case of constant discount of the social planner problem. In that case, the optimal depletion rate and the initial consumption of exhaustible resource are the slowest. On the contrary, they are the highest and the myopic behaviors lead to excessive consumption of exhaustible resources inevitably without commitment. Otherwise, in the case of partial commitment, the results are between the cases of full commitment and of no commitment. Therefore, with the hyperbolic time preference, the optimal depletion rate of resource depends on the commitment ability. Higher commitment ability leads to lower effective rate of time preference, and consequently, lower depletion rate and lower initial depletion value. The improvement of commitment ability can decrease the impatience and myopia behaviors, and contribute to the protection of the exhaustible resources.     

农村土地流转影响因素的理论与实证研究——基于农民阶层分化与产权偏好的视角

随着我国经济的发展和社会转型,农民群体逐渐分化为不同职业的农民阶层,由于职业选择的不同以及生活环境的变化,农民在经济收入、产权偏好等方面都出现了巨大的差异,这导致他们对土地流转意愿与决策行为的选择也出现分化,因此,研究由于农民职业分化导致的产权偏好不同及对土地流转的影响就具有重要现实意义.本文利用笔者对江苏省实地问卷调查所得的数据,在理论分析与研究假说的基础上,运用Lagistic模型对农民职业分化、产权偏好与农村土地流转的关系进行了实证分析.研究结果表明:文化程度、职业类别、非农收入比重、是否具有非农就业技能、是否拥有转让权、地权稳定性、地区虚拟变量对土地流转有正向影响,年龄则对土地流转有负向影响,而农业劳动力人数、土地的养老保障作用和是否具有抵押权则对土地流转决策没有显著影响.基于上述研究结论,本文提出了应强化土地产权、完善产权结构、大力发展非农产业和提供非农就业机会、提高农村劳动力职业技术素质、逐步建立和完善农村社会保障体系等政策建议.     

Role of Familiarity and Preference in Reproductive Success in Ex Situ Breeding Programs

Abstract: Success of captive‐breeding programs centers on consistent reproduction among captive animals. However, many individuals do not reproduce even when they are apparently healthy and presented with mates. Mate choice can affect multiple parameters of reproductive success, including mating success, offspring production, offspring survival, and offspring fecundity. We investigated the role of familiarity and preference on reproductive success of female Columbia Basin pygmy rabbits (Brachylagus idahoensis) as measured by litter production, litter size, average number of young that emerged from the burrow, and average number of young that survived to 1 year. We conducted these studies on pygmy rabbits at the Oregon Zoo (Portland, Oregon, U.S.A.) and Washington State University (Pullman, Washington, U.S.A.) from February to June 2006, 2007, and 2008. Before mating, we housed each female adjacent to 2 males (neighbors). Female preference for each potential mate was determined on the basis of behavioral interactions observed and measured between the rabbits. We compared reproductive success between females mated with neighbor and non‐neighbor males and between females mated with preferred and nonpreferred males. Our findings suggest that mating with a neighbor compared with a non‐neighbor and mating with a preferred neighbor compared with a nonpreferred neighbor increased reproductive success in female pygmy rabbits. Litter production, average number of young that emerged, and average number of young that survived to 1 year were higher in rabbits that were neighbors before mating than in animals who were not neighbors. Pairing rabbits with a preferred partner increased the probability of producing a litter and was significantly associated with increased litter size. In captive breeding programs, mates are traditionally selected on the basis of genetic parameters to minimize loss of genetic diversity and inbreeding coefficients. Our results suggest that integrating genetic information with social dynamics and behavioral measures of preference may increase the reproductive output of the pygmy rabbit captive‐breeding program. Our findings are consistent with the idea that allowing mate choice and familiarity increase the reproductive success of captive‐breeding programs for endangered species.     

Coastal landscape preference evaluation: A comparison among tourists in Greece

An evaluation of coastal landscape of pine forest in Greece by summer visitors of various nationalities was carried out. The visual preferences for a set of landscape, represented in photographs, expressed by these various nationality groups were compared. The subjects used in this research came from Greece, Germany, Italy, France, Great Britain, Austria, Yugoslavia, and Scandinavian countries. The findings show that there is an agreement over the basic preference, but, nevertheless, there are differences of opinion between the nationality groups that might be attributed to cultural influences and the effect of being familiar with their own environments. Since coastal landscape plays an important role in the tourist industry, these findings could be very useful to policy-making agencies.     

MULTICRITERION ANALYSIS OF FOREST WATERSHED MANAGEMENT ALTERNATIVES1

ABSTRACT: The impacts of alternative forest watershed management practices are examined from a multicriterion viewpoint in order to select the most satisfactory management scheme. The selection process is carried out using two types of multicriterion decision making techniques: the outranking types of ELECTRE I and II, and the distance-based type of compromise programming (CP). The process is illustrated using the U.S. Forest Service Beaver Creek Experimental Watershed in the Salt-Verde River Basin of Arizona as an example. The desired objectives of the experimental study and the alternative forest watershed resources management schemes are transformed into an evaluation matrix of alternatives versus criteria array. Analyses of the matrix using the aforementioned techniques result in a complete preference ordering of the feasible alternatives in the cases of ELECTRE LI and CP and a partial ordering when ELECTRE I is used. In addition, some sensitivity analyses have been performed and showed ELECTRE II and CP to be fairly robust with respect to parameter changes, while ELECTRE I being highly sensitive to changes in threshold levels. Overall the three techniques pointed out that 65 percent vegetation cut is the best management scheme, while the next best is shown to be 50 percent vegetation cut.     

Does risk of intraspecific interactions induce shifts in prey-size preference in aquatic predators?

Interactions between foragers may seriously affect individual foraging efficiency. In a laboratory study of handling time, prey value and prey-size preference in northern pike and signal crayfish, we show that risk of intraspecific interactions between predators does not affect handling time or value of prey. However, the presence of agonistic intraspecific interactors shifts prey-size preference in these predators. Neither northern pike nor signal crayfish foraging alone show a prey-size preference, while pike foraging among conspecifics prefer small prey, and crayfish foraging in groups prefer large prey. We ascribe the different outcomes in prey preference to differences in susceptibility to interactions: northern pike under risk avoid large prey to avoid long handling times and the associated risk of interactions, while signal crayfish foraging among conspecifics may defend themselves and their prey during handling, and thus select prey to maximise investment. In addition, the value of pike prey (roach) is low for very small prey, maximises for small prey, and then decreases monotonically for larger prey, while crayfish prey (pond snail) value is low for very small prey, has a maximum at small prey, but does not decrease as much for larger prey. Therefore, a large and easily detected snail prey provides a crayfish with as much value as a small prey. We conclude that interaction risk and predator density affect prey-size preference differently in these aquatic predators, and therefore has different potential effects on prey-size structure and population and community dynamics. Received: 4 October 1999 / Revised: 20 March 2000 / Accepted: 27 May 2000