Optimal control of nonlinear partially-unknown systems with unsymmetrical input constraints and its applications to the optimal UAV circumnavigation problem

Aimed at solving the optimal control problem for nonlinear systems with unsymmetrical input constraints, we present an online adaptive approach for partially unknown control systems/dynamics. The designed algorithm converges online to the optimal control solution without the knowledge of the internal system dynamics. The optimality of the obtained control policy and the stability for the closed-loop dynamic optimality are proved theoretically. The proposed method greatly relaxes the assumption on the form of the internal dynamics and input constraints in previous works. Besides, the control design framework proposed in this paper offers a new approach to solve the optimal circumnavigation problem involving a moving target for a fixed-wing unmanned aerial vehicle (UAV). The control performance of our method is compared with that of the existing circumnavigation control law in a numerical simulation and the simulation results validate the effectiveness of our algorithm

Quantized massive spin 1/2 fields on static spherically symmetric wormhole spacetimes

Title from PDF of title page (University of Missouri--Columbia, viewed on October 30, 2012).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Dissertation advisors: Dr. Aigen Li and Dr. David RetzloffIncludes bibliographical references.Vita.Ph. D. University of Missouri--Columbia 2012."July 2012"Traversable wormholes have become a subject of intensive studies since 1988 when Morris and Thorne published their paper which put forward the energy conditions for traversable wormholes. A number of researchers have calculated the stress-energy tensors of different fields but failed to find one that meets the requirement of the wormhole geometry. Some others find different schemes to sustain traversable wormholes but either on the Planck scale or hypothetically on a macroscopic scale. Groves has developed a method to compute the renormalized stress-energy tensor for a quantized massive spin ½ field in a general static spherically symmetric spacetime. Using this method, I have computed the renormalized stress-energy tensors of two quantized massive spin ½ fields in four static spherically symmetric wormhole spacetimes. The results of my calculation suggest that these two fields can be considered exotic. However, due to the technical difficulties in implementing this method, a series of approximations are used in the computation in order to make the problem mathematically tractable; but it is not clear under what physical circumstances these approximations could hold. Besides, the cases that I investigated turned out to involve unphysically large energy densities. Because of these reasons, no firm physical conclusions can be drawn.Includes bibliographical reference

Resonant Decay of Kinetic Alfv\'en Waves and Implication on Spectral Cascading

A general equation describing the resonant nonlinear mode-coupling among kinetic Alfv\'en waves (KAWs) is derived using nonlinear gyrokinetic theory, which can be applied to study the potentially strong spectral energy transfer of KAWs. As a first application, the parametric decay of a pump KAW into two sideband KAWs are studied, with particular emphasis on the cascading in perpendicular wavenumber. It is found that, for the "co-propagating" cases with all three KAWs propagating in the same direction along the equilibrium magnetic field line, it exhibits a dual cascading character in the perpendicular wavenumber space; while for the "counter-propagating" cases with one sideband propagating in the opposite direction with respect to the pump wave, it instead, can exhibit both dual and inverse cascading behaviors. The implications on SAW instability nonlinear saturation and charged particle transport in fusion plasmas is also discussed

Design driven user study workshop for Chinese startup innovation

The paper illustrates a serial user study workshop designed for startups seeking disruptive innovation and business opportunities based on the lean process from the point view of user-centered design approach. In the Chinese market, business process moves fast. The product development cycle is relatively short which makes it easy to be interrupted and changed. Making sure the product is targeting the right marketing segment is the key to business success. Therefore, innovation has to be created on the true needs of the accurate end users. User-centered design approaches have the natural advantage to forge innovation by defining the problems of the existing products usage for the users and creating the solution that seamlessly meets the potential demands of the product users. This capability of user-centered design is extremely suitable for the early stage of the startup innovation process especially in the customer identification, market positioning, and business model generation. User study is located in the core of this user-centered innovation process. Performing a good user study ensures the product is aimed at users’ needs, which guarantees once the product is given birth it is already well-positioned in the market sharing. This is the key to the success of startup business. In this paper, a serial workshop covers the topics from what are the user study methods suitable for the lean startup innovation, how to conduct an effective interview, and how to synthesize users’ insights and find new business opportunities. By doing the workshop we try to answer the following questions which ultimately influence the nurturing process in the incubator about how design thinking can intervene to create radical innovation in startup teams: why the design driven user study is so important to the startup business? What is design thinking in the non-design background startuper’s mind and how can they incorporate the mindset in the business operation? What Chinese business environment impacts in the innovation process and how could the startups position the empathy for the users as the key for the product success

On effective location-aware music recommendation

Ministry of Education, Singapore under its Academic Research Funding Tier