In this study, a robust interval-based minimax-regret analysis (RIMA) method is developed and applied to the identification of optimal water-resources-allocation strategies under uncertainty. The developed RIMAapproachcan address uncertainties with multiple presentations.Moreover, it can be usedfor analyzing all possible scenarios associated with different system costs/benefits and risk levels without making assumptions on probabilistic distributions for random variables. In its solution process, an intervalelement cost/benefit matrix can be transformed into an interval-element regret matrix, such that the decision makers can identify desired strategies based on inexact minimax regret (IMMR) criterion. Moreover, the fuzzy decision space is delimited into a more robust one through dimensional enlargement of the original fuzzy constraints. The developed method is applied to a case study of planning water resources allocation under uncertainty. The results indicate that reasonable solutions have been generated. They can help decision makers identify desired strategies for water-resources allocation with a compromise between maximized system benefit and minimized system-failure risk.

In this study, a dual-interval vertex analysis (DIVA) method is developed, through incorporating the vertex method within an interval-parameter programming framework. The developed DIVA method can tackle uncertainties presented as dual intervals that exist in the objective function and the left-and right-hand sides of the modeling constraints. An interactive algorithm and a vertex analysis approach are proposed for solving the DIVA model. Solutions under an associated a-cut level can be generated by solving a series of deterministic submodels. They can help quantify relationships between the objective function value and the membership grade, which is meaningful for supporting in-depth analyses of tradeoffs between environmental and economic objectives as well as those between system optimality and reliability. A management problem in terms of regional air pollution control is studied to illustrate applicability of the proposed approach. The results indicate that useful solutions for planning the air quality management practices have been generated. They can help decision makers to identify desired pollution-abatement strategies with minimized costs and maximized environmental efficiencies.

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.

提出了一种前置级采用两级串联固定阻尼孔的双喷嘴挡板水压伺服桥路模型，并对其进行了参量敏感性分析。探讨了喷嘴挡板位移、阀芯运动速度与阀芯两端压力的关系；运用正交设计方法研究了喷嘴直径、串联固定阻尼孔直径、阀芯直径及其运动速度、喷嘴挡板与喷嘴之间初始距离等参量对水压桥路特性的影响。结果表明，喷嘴直径以及喷嘴与挡板之间中位距离越小，阀芯与阀套之间配合间隙越大，阀芯直径越大，阀芯与阀套之间叠合长度越短，压力源压力越高，桥路控制的线性度越好；对于采用二级节流的水压伺服桥路，第一级固定阻尼孔直径越小，第二级固定阻尼孔直径越大，喷嘴前端流道直径越小，阀芯与阀套之间配合间隙以及阀芯直径越大，桥路响应就越快。这些研究结果为水压伺服阀样机的研制奠定了理论基础。

以试验研究的方式，分析、探讨了固定阻尼孔对水压伺服阀静态特性的影响，这些特性主要包括水压伺服阀的零位泄漏特性、空载流量特性、负载流量特性和压力特性等。试验结果表明：两级固定阻尼孔直径相差不大时，水压伺服阀静态特性较好；固定阻尼孔的加工误差导致阻尼特性不对称，并导致水压伺服阀静态特性对称性变差。