充分灌与调亏灌溉条件下桃树滴灌的耗水量研究

本文研究了充分灌与调亏灌溉条件下桃树滴灌的耗水量。在田间设置有两个处理，其一是在整个生育期以蒸发量的80%进行充分灌溉；其二是在果实生长缓慢期以蒸发量的20%进行亏缺灌溉，而在其它季节以蒸发量的80%进行充分灌溉。利用石膏块土壤水分传感器和中子仪分别测量了根区土壤水势和土壤含水量的变化，并实测了果实生长量、枝条生长量和产量。利用水量平衡法得出了在上述两种滴灌条件下桃树不同生育期的日均耗水量与蒸发皿系数。与充分灌比较，调亏灌溉对产量没有影响，灌水量减少了32%，并有效抑制了枝条生长。     

Cost monotonicity, consistency and minimum cost spanning tree games

We propose a new cost allocation rule for minimum cost spanning tree games. The new rule is a core selection and also satisfies cost monotonicity. We also give characterisation theorems for the new rule as well as the much-studied Bird allocation. We show that the principal difference between these two rules is in terms of their consistency properties.     

Generalizations of Ho–Lee’s binomial interest rate model I: from one- to multi-factor

In this paper a multi-factor generalization of Ho–Lee model is proposed. In sharp contrast to the classical Ho–Lee, this generalization allows for those movements other than parallel shifts, while it still is described by a recombining tree, and is a process with stationary independent increments to be compatible with principal component analysis. Based on the model, generalizations of duration-based hedging are proposed. A continuous-time limit of the model is also discussed. This research was supported by Open Research Center Project for Private Universities: matching fund subsidy from MEXT, 2004–2008 and also by Grants-in-Aids for Scientific Research (No. 18540146) from the Japan Society for Promotion of Sciences.     

洪水预报智能模型在中国半干旱半湿润区的应用对比

为探究不同洪水预报智能模型在我国半干旱半湿润区的应用效果,选用决策树、多层感知器、随机森林和支持向量机4种模型在陕西省3个典型流域进行逐时洪水预报;选择相关系数、纳什效率系数、均方根误差、平均绝对误差和相对误差等评价指标,比较不同预见期下4种模型在半干旱半湿润典型流域洪水预报的适用性。结果表明:在短预见期预报中,4种模型在半湿润区典型流域均可获得较高的预报结果,在半干旱典型流域模拟精度相对偏低,仅支持向量机模型满足预报要求;随着预见期延长,不同模型性能变化差异大,支持向量机模型整体稳定,在小流域实时洪水预报中具有明显优势;随机森林模型与决策树模型精度随预见期延长而缓慢下降,前者适应性更好;多层感知器模型精度随预见期延长而骤减,模型稳定性较差。     

基于实物期权法对R&D项目价值评估的研究——对布莱克-舒尔斯定价模型的改进

针对R&D项目投资的特点,探讨了采用布莱克一舒尔斯期权定价模型对R&D项目价值评估可能存在的缺陷,并提出一种改进方法,即将决策树和布莱克一舒尔斯定价模型结合运用,因为决策树能够模拟研发项目的阶段性决策过程,考虑到多个离散型不确定性因素的相关性,模拟并计算出对决策路径依赖的现金流,因此能克服纯粹使用布莱克一舒尔斯公式的不足,在考虑多个不确定性因素的影响下,实现对多阶段R&D项目价值的评估,作出正确的投资决策。     

基于灰关联法发动机故障诊断的研究

应用灰关联理论对发动机的故障进行诊断。灰关联分析属非函数型的序列模式,能有效处理杂散数据。通过建立工程机械发动机系统故障树,运用灰关联分析对关联度进行计算及排序,给出各种故障模式发生的可能性排序,从而为处理故障、控制故障的发生以及改进系统的可靠性提供理论依据。     

宁波市天一广场盆栽大树移植技术探讨

本文以天一广场盆栽大树成功移植经验为基础,详细论述了城市绿化建设中特殊条件下大树移植发方法,以期对类似园林工程施工有所帮助。     

我国股改中权证的价格泡沫及影响因素

本文针对我国股改中的百慕大权证提出了新的“模拟树-市场情绪”定价模型。该模型的实证研究结果表明中国权证市场价格存在严重高估;加入市场情绪指标后,通过建立多元回归模型得到了对于实际价格的显著的拟合结果,有力地解释了超出权证理论价格的实际价格所包含的情绪因素。本文最后对权证价格高估的原因及权证未来的走势进行了分析。     

Mangrove forests as a nature-based solution for coastal flood protection: Biophysical and ecological considerations

Nature-based coastal protection is increasingly recognised as a potentially sustainable and cost-effective solution to reduce coastal flood risk. It uses coastal ecosystems such as mangrove forests to create resilient designs for coastal flood protection. However, to use mangroves effectively as a nature-based measure for flood risk reduction, we must understand the biophysical processes that govern risk reduction capacity through mangrove ecosystem size and structure. In this perspective, we evaluate the current state of knowledge on local physical drivers and ecological processes that determine mangrove functioning as part of a nature-based flood defence. We show that the forest properties that comprise coastal flood protection are well-known, but models cannot yet pinpoint how spatial heterogeneity of the forest structure affects the capacity for wave or surge attenuation. Overall, there is relatively good understanding of the ecological processes that drive forest structure and size, but there is a lack of knowledge on how daily bed-level dynamics link to long-term biogeomorphic forest dynamics, and on the role of combined stressors influencing forest retreat. Integrating simulation models of forest structure under changing physical (e.g. due to sea-level change) and ecological drivers with hydrodynamic attenuation models will allow for better projections of long-term natural coastal protection.     

基于雪岭云杉树轮的阿克苏河干流冬季径流重建

基于阿克苏河上游高山区采集的雪岭云杉树轮样芯构建了雪岭云杉树轮宽度年表,结合阿克苏河干流径流数据解析了雪岭云杉长期生长与阿克苏河干流径流关系,并重建了阿克苏河干流1813—2015年冬季径流序列。结果表明:利用雪岭云杉树轮宽度年表重建的阿克苏河干流1813—2015年冬季径流序列模拟值与实测值吻合度较高,重建径流序列稳定可靠;1813—2015年阿克苏河干流冬季多年平均流量为82.19 m~3/s,共出现5次持续丰水期和3次持续枯水期,最长的枯水段持续17年(1943—1959年);阿克苏河干流冬季径流变化存在51 a、29 a、16 a周期,第一主周期为51 a。