生态水利工程设计在水利建设中的运用

水资源的合理、科学以及绿色的使用是确保国家高效成长以及保护社会正常运行的前提条件,因此创建生态水利工程具有至关重要的意义。现如今本国的水资源被污染以及浪费的程度愈来愈大,能够将水资源合理、可续的使用起来是水利创建当中最为核心的内容,因此本国的相关单位对于生态水利工程的创建有着极大的重视。针对于此,全文着重探讨了生态水利工程策划的意义、在创建水利工程当中生态水利工程策划需要遵守原则以及生态水利工程在水利创建当中的使用,仅供参考。     

桥梁病害对桥梁设计的启示分析

现阶段,随着社会经济的飞速发展,道路基础设施的建设速度逐渐加快。同时,随着各种各样桥梁病害问题的出现,对桥梁的承载能力造成了一定程度的影响。因此,及时防治桥梁病害有助于保障桥梁的安全性。论文结合某危桥改造项目,对桥梁的病害展开研讨,对病害的产生原因进行分析,并提供实用性的桥梁设计应对方法,以保证桥梁的耐久性与安全性。     

Joint Quantity/Quality Management of Groundwater

Economic literature on groundwater managementhas traditionally been split into two areas: there are papers that evaluate different schemes of dynamicaquifer management, considering that pumping costs vary with stock but ignoring water quality. On the other hand, there are papers that considercontamination problems caused by specificpollutants. This paper presents two alternative models for joint quantity-quality management, and it shows that existing models are in fact special cases of these. The framework isdynamic and considers both the stock of waterquantity and a stock measure of water quality. Optimal taxes are derived, and shown to be different from those in existing quantity-only or quality-only models. Implementationproblems are briefly discussed.     

The nature of the steady state in models of optimal growth under uncertainty

Summary. We study a one-sector stochastic optimal growth model with a representative agent. Utility is logarithmic and the production function is of the Cobb-Douglas form with capital exponent . Production is affected by a multiplicative shock taking one of two values with positive probabilities p and 1-p. It is well known that for this economy, optimal paths converge to a unique steady state, which is an invariant distribution. We are concerned with properties of this distribution. By using the theory of Iterated Function Systems, we are able to characterize such a distribution in terms of singularity versus absolute continuity as parameters and p change. We establish mutual singularity of the invariant distributions as p varies between 0 and 1 whenever . More delicate is the case . Singularity with respect to Lebesgue measure also appears for values such that . For and Peres and Solomyak (1998) have shown that the distribution is a.e. absolutely continuous. Characterization of the invariant distribution in the remaining cases is still an open question. The entire analysis is summarized through a bifurcation diagram, drawn in terms of pairs .Received: 9 April 2002, Revised: 29 October 2002, JEL Classification Numbers: C61, O41.Correspondence to: Tapan MitraThis research was partially supported by CNR (Italy) under the "Short-term mobility" program and by M.U.R.S.T. (Italy) National Group on "Nonlinear Dynamics and Stochastic Models in Economics and Finance" . We are indebted to Rabi Bhattacharya for providing us with the reference to Solomyak's (1995) paper. The present version has benefitted from comments by Mukul Majumdar and two anonymous referees.     

The equilibrium set of two-player games with complementarities is a sublattice

Summary. I prove that the equilibrium set in a two-player game with complementarities, and totally ordered strategy spaces, is a sublattice of the joint strategy space. Received: May 31, 2001; revised version: October 4, 2002     

Ex-post full surplus extraction,straightforwardly

Consider an estimate of the common value of an auctioned asset that is symmetric in the bidders’ types. Such an estimate can be represented solely in terms of the order statistics of those types. This representation forms the basis for a pricing rule yielding truthful bidding as an equilibrium, whether bidders’ types are affiliated or independent. We highlight the link between the estimator and full surplus extraction, providing a necessary and sufficient condition for ex-post full surplus extraction, including the possibility of independent types. The results offer sharp insights into the strengths and limits of simple auctions by identifying the source of informational rents in such environments. Harstad acknowledges hospitable accommodation by the Fuqua School of Business, Duke University, and the Olin School of Business, Washington University in St. Louis, during parts of this research. We are grateful for comments and suggestions from Richard McLean and Jeroen Swinkels.     

基于生态学思考的小城镇新区规划设计新理念

基于生态学的思考,小城镇新区规划设计应树立五个新理念:深化人本思想、突出文化内涵、注重景观设计、树立超前意识、发扬务实精神。新理念在实践过程中体现在:营造人性化的小城镇新区、塑造地方性的小城镇特色、打造园林式的小城镇景观、构造灵活性的小城镇格局、绘就实用性的小城镇蓝图。     

Provision Point Mechanisms and Field Validity Tests of Contingent Valuation

Past field validity tests of contingent valuation have relied on voluntary contribution mechanisms to elicit actual willingness to pay, and may overestimate hypothetical bias because of free riding in the actual contributions. This paper argues that provision point mechanisms are a preferred alternative for field validity tests of contingent valuation because they increase the proportion of demand revealed in cases in which public goods can be provided in a step function. The results of a contingent valuation validity study of participation in a green electricity pricing program that uses a provision point mechanism are reported, and hypothetical open-ended and dichotomous choice responses are compared to actual participation. Calibration of hypothetical responses is also explored.     

Societal preferences for fertility treatment in Australia: a stated preference discrete choice experiment

Objective: To investigate preferences for fertility treatment from the Australian general population with the aims of calculating the willingness to pay in tax contribution for attributes (characteristics) that make up treatment and for an “ideal” fertility treatment program. We also assessed whether willingness-to-pay varies by the relationship status or sexual orientation of the patient.

Methods: A stated preference discrete choice experiment was administered to a panel of 801 individuals representative of the Australian general population. Seven attributes of fertility treatment under three broad categories were included: outcome, process, and cost. Attributes were identified through published literature, focus group discussions, expert knowledge, and a pilot study. A Bayesian fractional experimental design was used, and data analysis was performed using a generalized multinomial logit model. Further analyses included interaction terms and latent class modeling.

Results: Six of the seven attributes influenced the choice of a treatment program. Under process attributes, individuals preferred: continuity of care of clinic staff, where patients are seen by the same doctor but different nurses at each visit; “alternative” treatments being offered to all patients; and onsite clinic counseling and peer-support groups. Personalization and tailoring of the treatment journey were not important. Among outcome attributes, the improved success rate of having a baby per cycle and significant side-effects were considered important. Cost of treatment also influenced the choice of treatment program. Individual preferences for fertility treatment were not associated with patients’ relationship status or sexual orientation. Latent class modeling revealed sub-groups with distinct fertility treatment preferences.

Conclusion: This study provides important insights into the attributes that influence the preferences of fertility treatment in Australia. It also estimates socially-inclusive willingness-to-pay values in tax contributions for an “ideal” package of treatment. The results can inform economic evaluations of fertility treatment programs.