In this study, a two-stage fuzzy robust integer programming (TFRIP) method has been developed for planning environmental management systems under uncertainty. This approach integrates techniques of robust programming and two-stage stochastic programming within a mixed integer linear programming framework. It can facilitate dynamic analysis of capacity-expansion planning for waste management facilities within a multi-stage context. In the modeling formulation, uncertainties can be presented in terms of both possibilistic and probabilistic distributions, such that robustness of the optimization process could be enhanced. In its solution process, the fuzzy decision space is delimited into a more robust one by specifying the uncertainties through dimensional enlargement of the original fuzzy constraints. The TFRIP method is applied to a case study of long-term waste-management planning under uncertainty. The generated solutions for continuous and binary variables can provide desired waste-flow-allocation and capacity-expansion plans with a minimized system cost and a maximized system feasibility.

In this study, an interval-parameter multi-stage stochastic linear programming (IMSLP) method has been developed for water resources decision making under uncertainty. The IMSLP is a hybrid methodology of inexact optimization and multi-stage stochastic programming. It has three major advantages in comparison to the other optimization techniques. Firstly, it extends upon the existing multi-stage stochastic programming method by allowing uncertainties expressed as probability density functions and discrete intervals to be effectively incorporated within the optimization framework. Secondly, penalties are exercised with recourse against any infeasibility, which permits in-depth analyses of various policy scenarios that are associated with different levels of economic consequences when the promised water-allocation targets are violated. Thirdly, it cannot only handle uncertainties through constructing a set of scenarios that is representative for the universe of possible outcomes, but also reflect dynamic features of the system conditions through transactions at discrete points in time over the planning horizon. The developed IMSLP method is applied to a hypothetical case study of water resources management. The results are helpful for water resources managers in not only making decisions of water allocation but also gaining insight into the tradeoffs between environmental and economic objectives.

The shapes and geometrical parameters of nozzles are key factors for fluidics. The relationship among the reaction thrust, flow rate pressure, diameter do and length L of a cylinder nozzle is analyzed theoretically. The simulation of the flow field characteristics was conducted via the FLUENT computational fuid dynamics package. Effects of the inlet conditions and the nozzle dimensions on the reaction thrust of a water jet were addressed particularly. The reaction thrust experiments were performed on a custom-designed test apparatus. The experimental results reveal that a) the nozzle diameter and the inlet conditions exert great influence on the water jet reaction thrust; and b) for L_<4d0, where the nozzle is treated as a thin plate-orifice, the reaction thrust is independent of nozzle length; for L>4d0, where the nozzle is treated as a long orifice, the reaction thrust can reach maximum under the condition of a certain flow rate. These findings lay a theoretical foundation for the design of nozzles and have significant value, especially for the future development of high-pressure water-jet propulsion technology.

近些年通过对液压元件污染状况的测量分析，有研究针对典型的单回路液压系统成功建立了不确定条件下的污染控制数学模型。本文在此基础上补充考虑了实际系统中部分参数间的相互关联以及泵的污染磨损机理，拟在不损坏关键液压元件的前提下，通过安装合适的过滤器及规划合理的更换周期，以降低系统运行的费用。该模型利用一致逼近的数学方法对大量的数据进行描述，极大精简了模型。同时，全文引入区间规划的优化理论，对实验算例进行分析并证实了该模型的有效性。

根据多阶段随机线性规划方法（MSLP）的原理，修正了原有模型中关于系统各处污染物侵入/产生率的描述，将概率密度函数引入到污染物侵入/产生率中能更有效地表达系统在实际运行过程中污染物浓度的变化规律。以一个典型液压系统污染控制区间参数优化模型为基础，针对液压系统中油液污染浓度随时间变化的不可预测性，引入多阶段随机优化方法，通过多层假设和概率分布函数，建立了基于区间参数多阶段随机线性规划的优化决策模型。多阶段随机优化方法的引入体现了液压元件的污染物生成率在元件正常运行期间先后经历了加速衰减、减速衰减和稳定3个阶段，对于准确描述污染物浓度的变化规律以及有效预算液压系统的运行成本具有重要意义。