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Abstract:Water resource allocation is the process of assessing and determining a mechanism on how water should be distributed among different regions, sectors and users. Over the recent decades, the optimal solution for water resource allocation has been explored both in centralised and decentralised mechanisms. Conventional approaches are under central planner suggesting a solution which maximises total welfare to the users. Moving towards the decentralised modelling, the techniques consider individuals as if they act selfishly in their own favour. While central planner provides an efficient solution, it may not be acceptable for some selfish agents. The contrary is true as well in decentralised solution, where the solution lacks efficiency leading to an inefficient usage of provided resources. This paper develops a parallel evolutionary search algorithm to introduce a mechanism in re-distributing the central planner revenue value among the competing agents based on their contribution to the central solution. The result maintains the efficiency and is used as an incentive for calculating a fair revenue for each agent. The framework is demonstrated and discussed to allocate water resources along the Nile river basin, where there exist eleven competing users represented as agents in various sectors with upstream-downstream relationships and different water demands and availability.

Plasma actuators have become the topic of interest of many researchers for the purpose of flow control. They have the advantage of manipulating the flow without the need for any moving parts, a small surface profile which does not disturb the free stream flow, and the ability to switch them on or off depending on the particular situation (active flow control). Due to these characteristics they are becoming very popular for flow control over aircraft wings. The objective of the current study is to examine the effect of the actuator surface temperature on its performance. This is an important topic to understand when dealing with real life aircraft equipped with plasma actuators. The temperature variations encountered during a flight envelope may have adverse effects in actuator performance. A peltier heater along with dry ice are used to alter the actuator temperature, while particle image velocimetry (PIV) is utilised to analyse the flow field. The results show a significant change in the induced flow field by the actuator as the surface temperature is varied. It is found that for a constant peak-to-peak voltage the maximum velocity produced by the actuator depends directly on the dielectric surface temperature. The findings suggest that by changing the actuator temperature the performance can be maintained or even altered at different environmental conditions.

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The standard dielectric barrier discharge plasma actuator, in which an asymmetric arrangement of electrodes leads to momentum coupling into the surrounding air, has already demonstrated its capability for flow control. The new design of such an actuator exploits the multi-encapsulated electrodes to produce higher velocities providing more momentum into the background air. As the number of encapsulated electrodes increases and other variables such as the driving frequency and voltage amplitude are considered, finding the optimum actuator configuration for increasing the induced velocity becomes a challenge. Specially the task is prohibitive if it is implemented on an ad hoc basis. This paper uses D-optimal design to identify a handful of experiments, for which the velocity is obtained by Particle Imaging Velocimetry measurement. Afterwards, the velocity is modelled through a surrogate modelling practice, and the model is validated both experimentally and statistically. To find the optimum actuator configuration, numerical optimisation is conducted and the results are investigated through experiment. The results show that the surrogate modelling approach provides a cheap and yet efficient method for systematically investigating the effect of different parameters on the performance of the plasma actuator.