Micro Aerial vehicle: Experimental Aerodynamics optimization

Micro aerial vehicle has played more and more important rules, not only in the military. But also in civil applications nowadays. MAV differs from normal aircrafts due to different characteristics. Studying MAV aerodynamic leads to an optimized successful design. This report constitutes of, as the title for this project suggests; the basic details and understanding of unmanned aerial vehicle. The objective of this project is to establish methods of engineering calculations required for the calculation of lift and drag force and all the factors that affects the flight. The scope of study in this project is to design and fabricate an unmanned aerial vehicle and then experiment it in the wind tunnel. While the methodology is based on the data that been gathered during the research and how the optimize the aerodynamics of the flight. The outcome expected from this project is to choose the suitable material for the design of the MAV, as well as to conclude the best conditions that can be applied to the system for maximum efficiency and least cost. Since this is just a preliminary report, more researches and readings must be done in future, in order to obtain the useful information such as the complete design of the MAV and how to do the perfect calculation for the flight to have the maximum efficiency and do not face any difficulties while flying

DESIGN AND PERFORMANCE TESTING OF A NOVEL 3-FLUID LIQUID-TO-AIR MEMBRANE ENERGY EXCHANGER

Liquid-to-air membrane energy exchangers (LAMEEs) allow simultaneous heat and moisture transfer between air and desiccant solution streams that are separated by semi-permeable membranes. Moisture transfer between the air and desiccant solution is accompanied by the release/absorption of phase change energy which increases/decreases the temperature of the desiccant solution as it flows through the exchanger. The resulting change in the desiccant solution temperature decreases the driving potential for heat and moisture transfer (i.e. the differences between the air and desiccant solution temperatures and vapor pressures), which decreases the rates of heat and moisture transfer between the air and desiccant solution inside the exchanger. To overcome this problem, a novel 3-fluid LAMEE prototype is designed, built and tested. The 3-fluid LAMEE is composed of several adjacent parallel air and solution channels separated by semi-permeable membranes with refrigerant tubes within each solution channel. The aim of these refrigerant tubes is to reduce the change in the desiccant solution temperature inside the exchanger to guarantee high differences between the air and desiccant solution temperatures and vapor pressures along the entire length of the exchanger. This thesis has three main objectives. The first objective is to determine the practical nominal air and solution channel widths for flat-plate LAMEEs, and the effects of flow maldistribution caused by membrane deflections on the performance of flat-plate LAMEEs. The results in this thesis show that the practical air and solution channel widths for flat-plate LAMEEs are 5-6 mm and 1-2 mm, respectively. The second objective is to test and compare the rates of heat and moisture transfer between the air and desiccant solution in 3-fluid and 2-fluid LAMEEs under several operating conditions. Results show that the 3-fluid LAMEE can achieve the same heat and moisture transfer rates between the air and desiccant solution as a 2-fluid LAMEE at lower desiccant solution mass flow rates and with smaller membrane surface areas. Therefore the size of LAMEEs can be significantly decreased if refrigerant tubes are installed inside the solution channels. The third objective is to present performance definitions for evaluating the overall performance of 3-fluid LAMEEs. Unlike the traditional energy exchanger effectiveness equations, results show that the overall performance definitions can be used to evaluate the overall sensible and latent effectivenesses of 3-fluid LAMEEs and are less sensitive to the inlet refrigerant temperature

Evolutionary Search Techniques with Strong Heuristics for Multi-Objective Feature Selection in Software Product Lines

Software design is a process of trading off competing objectives. If the user objective space is rich, then we should use optimizers that can fully exploit that richness. For example, this study configures software product lines (expressed as feature models) using various search-based software engineering methods. Our main result is that as we increase the number of optimization objectives, the methods in widespread use (e.g. NSGA-II, SPEA2) perform much worse than IBEA (Indicator-Based Evolutionary Algorithm). IBEA works best since it makes most use of user preference knowledge. Hence it does better on the standard measures (hypervolume and spread) but it also generates far more products with 0 violations of domain constraints. We also present significant improvements to IBEA\u27s performance by employing three strong heuristic techniques that we call PUSH, PULL, and seeding. The PUSH technique forces the evolutionary search to respect certain rules and dependencies defined by the feature models, while the PULL technique gives higher weight to constraint satisfaction as an optimization objective and thus achieves a higher percentage of fully-compliant configurations within shorter runtimes. The seeding technique helps in guiding very large feature models to correct configurations very early in the optimization process. Our conclusion is that the methods we apply in search-based software engineering need to be carefully chosen, particularly when studying complex decision spaces with many optimization objectives. Also, we conclude that search methods must be customized to fit the problem at hand. Specifically, the evolutionary search must respect domain constraints