This thesis investigates the feasibility of producing electricity and cooling simultaneously utilising low-grade heat sources by incorporating an expander within the adsorption cooling system or by integrating an Organic Rankine Cycle with water adsorption cooling system. Advanced physical adsorbent materials have been investigated for the first time to generate cooling and electricity simultaneously utilising CPO-27(Ni), MIL101(Cr), and AQSOA-Z02 and compared to commonly used Silica-gel. Two innovative configurations of water adsorption systems for cooling and electricity were investigated. In the first configuration, the two-bed basic adsorption cooling system (BACS) is improved by including an expander within the system. In the second configuration, the BACS and ORC cycle are integrated. Four different scenarios of systems integration based on the way of powering the ORC and the adsorption system were investigated. Also, detailed CFD simulations of small-scale radial inflow turbines are developed for both configurations. Also, a novel experimental facility is developed to integrate ORC with two-bed adsorption cooling system to validate the numerical models and proof the concept of producing power as well as cooling, where maximum specific cooling power of 252 W/kgads and specific power and of 162 W/kgads can be achieved with maximum deviation of less than 17%.

This research introduces two different methods that are Levy Flight and Hooke and Jeeves to the Bees Algorithm with the aim of improving the convergence speed and its robustness. Both methods are incorporated to the Bees Algorithm at neighbourhood search of the elite bees since that particular locations are the most promising area during optimisation process. Each Bees Algorithm and the newly incorporated method with thirteen different parameter settings are subjected to fifteen different benchmark test functions. These benchmark test functions are represented with different characteristics in terms of its differentiability, separability, scaleability, and modality. Bees Algorithm with Levy-flight method incorporated to the local search performs excellent result for 13 out of 15 functions against standard Bees Algorithm in terms of its success rate and convergence speed in which it is validated by the statistical T test. As a matter of fact, the new method indicates better robustness for 13 functions in terms of achieving good result for solving different types of optimisation problems. For the Bees Algorithm with Hooke and Jeeves method, the new approach reaches a relatively better performance compared with standard Bees Algorithm in which one parameter excels at reaching optimum solution for most of the test functions.

<p>Over the years, the properties of nanoparticle-reinforced composites have been investigated regarding how the overall mechanical properties of the composites can be influenced by weight percentages, particle size, and types of reinforcement. The current advanced material processing technology allows people to obtain customized materials. However, making composite materials is usually costly and time-demanding, and some composite waste does not easily degrade. This computational study on composites provides a promising solution to these problems. In this research, a methodology of studying nanoparticle-reinforced polymer composites is developed, which allows the simulation of mechanical properties with multiscale computational approach. First, an RVE model of general nanoparticle-reinforced composites is constructed at nanoscale, and a computational study is made to examine the tensile behavior of the RVE on LS-DYNA. Second, a sensitivity study is conducted to optimize the mesh size with regards to simulation accuracy and computational time. Also, the model is validated by comparing the results from simulation with published data. Third, RVE models are applied to develop multiple models at microscale featured with various nanoparticles reinforcement dosages and orientation. In the end, data from tensile experiments on VGCNF are utilized to verify the models. It is found that using RVE models shortened the simulation times significantly while maintaining relatively high accuracy. Also, those models can be extensively applied to simulate various nanocomposites at multiple scales, which will fill the gap of simulation at between nanoscale and microscale.

<p>The control of flexible systems is a broad and active field of research due to the prominence and innate challenge of controlling complex systems in demanding environments. One well-proven technique for eliminating vibration in such systems is the implementation of a command shaping technique called input shaping. By designing a command which quickly performs a desired move without exciting oscillatory dynamics, input shaping is an excellent means of efficiently controlling vibration. This approach is also useful in mitigating vibration due to known force disturbances to a system if they are considered as initial conditions. Although unable to account for unknown disturbances by itself, input shaping can be implemented alongside a feedback controller to account for such externalities. This thesis presents new techniques to advance the state of the art in input shaping control to account for both known and unknown disturbances.

Thesis (Nav.E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1999. / Includes bibliographical references (leaves 97-98). / A finite difference computer model is developed to simulate the exposure statistics of a radio frequency buoyant antenna as it is towed in a random seaway. The model allows the user to prescribe antenna properties (length, diameter, density, etc.), sea conditions ( significant wave height, development of sea), and tow speed. The model then simulates the antenna-sea interaction for the desired duration to collect statistics relating to antenna performance. The model provides design engineers with a tool to predict antenna performance trends, and conduct design tradeoff studies. The antenna envisioned is a submarine floating antenna which would enable communications at speed and depth, greatly enhancing the stealth and survivability of the US Navy's submarine force. / by Gary A. Ulrich. / S.M. / Nav.E.

Thesis (Ocean E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1988, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1988. / Includes bibliographical references. / by Constantinos L. Stergiakis. / M.S. / Ocean E.

<p> Radiative heat transfer in participating media is among the most challenging computational engineering problems due to the complex nonlinear, nonlocal nature of radiation transport. Many approximate methods have been developed in order to resolve radiative heat transfer in participating media; but approximate methods, by the nature of their approximations, suffer from various shortcomings both in terms of accuracy and robustness. The only methods that can resolve radiative transfer accurately in all configurations are the statistical Monte Carlo-based methods. While the Monte Carlo (MC) method is the most accurate method for resolving radiative heat transfer, it is also notoriously computationally prohibitive in large-scale simulations. To overcome this computational burden, this study details the development of a quasi-Monte Carlo (QMC) method for thermal radiation in participating media with a focus on combustion-related problems. The QMC method employs a low-discrepancy sequence (LDS) in place of the traditional random number sampling mechanism used in Monte Carlo methods to increase computational efficiency. In order to analyze the performance of the QMC method, a systematic comparison of accuracy and computational expense was performed. The QMC method was validated against formal solutions of radiative heat transfer in several one-dimensional configurations and extended to three practical combustion configurations: a turbulent jet flame, a high-pressure industrial gas turbine, and a high-pressure spray combustion chamber. The results from QMC and traditional Monte Carlo are compared against benchmark solutions for each case. It is shown that accuracy of the predicted radiation field from QMC is comparable to MC at lower computational costs. Three different low-discrepancy sequences&mdash;Sobol, Halton, and Niederreiter&mdash;were examined as part of this work. Finally, recommendations are made in terms of choice of the sequence and the number of the dimensions of the LDS for combustion-relevant configurations. In conclusion, significant improvements in computational costs and accuracy seen in the QMC method makes it a viable alternative to traditional Monte Carlo methods in high-fidelity simulations. </p><p>

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1994, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1994. / Includes bibliographical references (leaves 70-72). / by He Huang. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1995, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1995. / by Jocelyn S.J. Turgeon. / M.S.

Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1993, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1993. / Includes bibliographical references (leaves 108-110). / by David Michael McGee. / M.S. / Nav.E.