拱坝及其优化方法的发展现状与展望

拱坝设计尤其是优化设计问题是近年来众多水利水电专家学者所关注的焦点,并越来越多的受到了人们的重视。简要回顾了拱坝的发展历史及现状,总结了拱坝优化的若干理论方法,最后指出拱坝优化在工程应用中的发展前景。     

土地整治工程量复核的实践

研究目的:鉴于目前土地整治项目越来越多,验收任务也越来越重的现状,如何既保证验收质量又提高验收效率是本文研究的出发点和归宿点。研究方法:实例分析法。研究结果:在项目竣工验收前开展工程量复核工作,不但可以保证工程的验收质量,同时也能大大提高验收效率,这一点可以从云南省两年多的土地整治工程量复核实践得到证明。研究结论:土地整治工程量复核是一项重要的基础性技术工作,能在保证工程的验收质量前提下提高验收工作效率、树立政府部门的良好形象,值得借鉴和推广。     

基于DPSIR模型的土地生态安全评价研究——以广东省佛冈县为例

针对佛冈县的土地生态的实际状况,基于"驱动力-压力-状态-影响-响应"(DPSIR)模型,构建土地生态安全评价指标体系,运用最优组合赋权法确定指标权重及土地生态安全综合评价模型对该区域进行评价。结果表明:1998—2008年佛冈县土地生态安全整体状况不断改善,生态安全综合指数从1998年的0.2567增至2008年的0.5858,生态安全水平处在从"风险级"状态转向"比较安全"状态的过程;从相关性分析来看,响应指标对土地生态安全水平的提高起主要的作用,但随着社会经济的加速发展,需要协调好各方面的矛盾,缓解资源环境的压力,使得土地生态环境朝着更好的方向迈进。     

The Optimal Timing of Adoption of a Green Technology

We study the optimal timing of adoption of a cleaner technology and its effects on the rate of growth of an economy in the context of an AK endogenous growth model. We show that the results depend upon the behavior of the marginal utility of environmental quality with respect to consumption. When it is increasing, we derive the capital level at the optimal timing of adoption. We show that this capital threshold is independent of the initial conditions on the stock of capital, implying that capital-poor countries tend to take longer to adopt. Also, country-specific characteristics, as the existence of high barriers to adoption, may lead to different capital thresholds for different countries. If the marginal utility of environmental quality decreases with consumption, a country should never delay adoption; the optimal policy is either to adopt immediately or, if adoption costs are “too high”, to never adopt. The policy implications of these results are discussed in the context of the international debate surrounding the environmental political agenda.      

中国基本养老保险最优财政支出规模测算——基于柯布-道格拉斯生产函数的一项研究

以内生增长理论为基础,运用巴罗的财政支出自然效率条件和改进的柯布-道格拉斯生产函数分别对中国城镇职工基本养老保险和城乡居民基本养老保险的最优财政支出规模进行测算,发现中国城镇职工基本养老保险和城乡居民基本养老保险的最优财政支出规模分别为2.33%和0.81%,目前两项养老保险的财政支出皆已超过了最优财政支出规模。为缓解养老保险的财政补贴压力,保证养老保险制度的良性运行,建议落实划转国有资本充实全国社会保障基金政策,实施基础养老金全国统筹,激发城镇职工和城乡居民缴费的积极性。     

组织内部信任-理性控制最优模型的建立

信任一理性控制程度的变化在组织的不同群体中会引起收益、成本、风险及员工行为变化的差异，这种差异使得信任对于组织中不同群体的价值有所不同，从而也使不同群体的最优信任水平有所不同。群体的工作性质、拥有资源对组织的价值以及组织对其的依赖程度等，都会影响到组织应达到的最优信任一理性控制程度。影响信任产生的因素会使组织现实的信任水平与最优信任水平不一致，必须通过重构信任关系或重新寻找合作对象来解决这一问题。     

居民住房区位选择问题研究

以行为区位理论为理论基础,摒弃在选择住房过程中对房屋价格的研究,仅从居民个人行为特征出发,分析购房者对区位和居住空间的偏好,以及二者之间的关系.同时对影响消费者居住区位选择的社会结构和因素与个人住房选择行为之间的相互作用进行深入的研究,并解释了消费者是如何在最优区位与次优区位之间进行抉择的.     

中国养老保险最优缴费率的实证分析——基于贴现因子和劳动增长率差异的分析

从个人效用和社会福利最大化的角度出发,养老保险制度存在着最优的缴费率.最优缴费率与资本产出弹性a、未来效用的贴现因子p、人口增长率n、有效劳动增长率g、个人工资与社会平均工资的比例λ等参数有关.结合中国现实,在其他参数不变的前提下,依据贴现因子和劳动增长率的变动能够形成四组组合模式.模拟结论表明,现行养老保险制度的社会统筹缴费率是符合福利最大化的最优缴费率;现行养老保险制度的个人账户缴费率与实现福利最大化的最优个人账户缴费率相比是偏低的;缴费期的长短与最优社会统筹缴费率的高低成正比而与最优个人账户缴费率的高低成反比;有效劳动增长率的高低与最优社会统筹缴费率成正比而与最优个人账户缴费率成反比.     

特许权价值、最优关闭策略和存款保险定价

随着存款保险制度的推出以及金融机构退出机制的完善,国家声誉将逐渐退出银行无形资本。在激励相容的金融监管趋势下,特许权价值等市场约束力量会显著影响到商业银行的风险承担。在此逻辑基础上,以我国16家上市商业银行为研究对象,一方面探讨特许权价值影响下不同产权结构的商业银行的最优救助机制,另一方面通过最优救助临界指标,利用银行重组模型,推导合理的存款保险风险差别费率。     

Pareto-improving social optimal pricing schemes based on bottleneck permits for managing congestion at a merging section

Akamatsu, Sato, and Nguyen (2006 Akamatsu, T., Sato, S., &; Nguyen, X. L. (2006). Tradable time-of-day bottleneck permits for morning commuters (in Japanese). JSCE Journal of Infrastructure Planning 62(4), 605–620.[Crossref] , [Google Scholar]) proposed a first-best pricing scheme based on the concept of bottleneck permits. The scheme allows permit holders to pass a bottleneck at specified times and is shown to be able to minimize social cost. However, the scheme is not always Pareto-improving in that it may harm some drivers. The objective of this study is to design Pareto-improving pricing scheme with bottleneck permits for a V-shaped two-to-one merge bottleneck. First, the paper formulates the morning commute model in the network and describes the arrival time choice equilibrium in the network with merging bottleneck. Secondly, we show that the first-best pricing scheme with bottleneck permits for this V-shaped network does not always achieve a Pareto improvement, with the cost of one group of drivers is increased by the permit pricing, a phenomena akin to the bottleneck paradox of Arnott, de Palma, and Lindsey (1993 Arnott, R., de Palma, A., &; Lindsey, R. (1993). Properties of dynamic traffic equilibrium involving bottlenecks, including a paradox and metering. Transportation Science 27(2), 148–160.[Crossref], [Web of Science ®] , [Google Scholar]). We propose three implementations of bottleneck permits for Pareto-improving: (1) merging priority rule is included in the bottleneck permits scheme by creating different market for each origin; (2) the permit revenues are refunded as monetary compensation to drivers whose cost is increased; and (3) the permit revenues are used to expand bottleneck capacity. For each implementation, we derive their equilibrium solutions and demonstrate that the Pareto improvement is achieved and social cost is decreased by using the permit revenues for expanding the bottleneck capacity.