Browsing by Subject "Applications"
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Item Addressing uncertainty and modeling error in the design and control of process systems : methods and applications(2016-08) Wang, Siyun, Ph.D.; Baldea, Michael; Edgar, Thomas F.; Rochelle, Gary T.; Truskett, Thomas M.; Biros, GeorgeA process system faces the challenge of uncertainty throughout its lifetime. At the design stage, uncertainty originates from inaccurate knowledge of design parameters and unmeasured or unmeasurable ambient disturbances. Oftentimes, designers choose to increase system size to account for uncertainty and fluctuations; however, this approach has an economic limit, past which the capital expenditure outweighs the potential operational benefits. In the operational stage, uncertainty is manifest, amongst others, in fluctuations in operating conditions, market demand and raw material availability. Another type of uncertainty in (modern) process operations is related to the quality of process models that are used for making control and operational decisions. Of particular importance is the quality of the dynamic models that are used in real-time optimal control computations. The chemical industry has been the pioneer (and is currently the leader) of model predictive control (MPC) implementations, whereby the control moves are computed, over a receding time horizon, by solving an optimal control problem at each time step. While uniquely able to deal with large-scale, non-square constrained systems, MPC is vitally dependent on the predictive abilities of the built-in model. Changes in plant conditions are a a source of uncertainty in this case as-well, leading to a discrepancy (mismatch) between the model predictions and the true plant behavior. In this dissertation, I address the problems of design under uncertainty and plant-model mismatch. For the former, identification-based optimization (IBO) framework is proposed as a new, computationally efficient framework for optimizing the design of dynamic systems under uncertainty problem. The framework uses properly designed pseudo-random multilevel signals (PRMS) to represent time-varying uncertain variables. This allows us to formulate the design under uncertainty problem as a dynamic optimization problem. A solution algorithm is proposed using a sequential approach. Several application examples are discussed, demonstrating the superior computational performance of the IBO approach. Furthermore, an extension of the method that explicitly considers the tradeoff between conservativeness and dynamic performance is introduced. The latter, plant-model mismatch problem, is addressed using a novel autocovariance-based approach. Under appropriate assumptions, an explicit relation is established between the autocovariance of the process output and the plant-model mismatch terms, represented either in a step response model or a transfer function model. It is demonstrated that an asymptotically correct set of estimates of the values of plant-model mismatch for each model parameters is the global minimizer of the discrepancy between the autocovariance predicted using the relation and the autocovariance calculated from a data set collected from closed-loop operating data. Extensions of this approach handle cases where the active set of the MPC is changing over time and there are setpoint change and measurable disturbances occur in the control loop.Item Applications of calculus : summary of Dr. Stephen McAdam’s summer course Mathematics Department at the University of Texas at Austin(2010-08) Lucas, Jeremiah Wayne; Armendáriz, Efraim P.; Daniels, MarkThe aim of this paper is to summarize Professor McAdam’s course on the applications of calculus by showing how calculus can be applied within mathematical situations by understanding concepts in physics. Aside from using calculus to assist in maximizing or minimizing situational problems, it is important to understand how the rules of calculus came to be. This paper shows origins of a few of the many rules used in calculus, applications in economics, plane flight, dogs fetching sticks, and relativity in space.Item Chameleon : rapid deployment of adaptive communication-aware applications(2009-12) Jun, Taesoo; Julien, Christine, D. Sc.Mobile ad hoc networks create communication links without the aid of any infrastructure, forwarding packets among mobile nodes. The MANET research community has identified several fundamental challenges, among which the most prominent is discovering an optimal route between two nodes. Existing work has proposed a plethora of routing protocols. Since each protocol implements its own philosophy and algorithm to target a specific purpose, routing protocols in MANETs show very different characteristics. Selecting a particular protocol for an application or deployment environment involves evaluating many complex inter-dependent tradeoffs and can be an overwhelming task for an application designer. However, this decision can have a significant impact on the success of a system in terms of performance, cost, and responsiveness. Emerging distributed applications deployed in MANETs inherently experience highly dynamic situations, which necessitate real-time routing protocol selection in response to varying scenarios. Most of the relevant research in this area relies on simulation studies or empirical analysis to select a routing protocol, requiring an infeasible amount of time and resources for the approaches to be used in real-time decision making. In my dissertation work, I designed the Chameleon framework to facilitate real-time routing protocol decisions based on given application and environmental characteristics. My approach develops analytical models for important network layer performance measures capturing various inter-dependent factors that affect routing protocol behavior. I provide an analytical framework that expresses protocol performance metrics in terms of environment-, protocol-, and application-dependent parameters. This effort has resulted in detailed models for two important metrics: end-to-end delay and throughput. I specify detailed models for the parameters embedded in the models with respect to the ability of network deployers, protocol designers, and application developers to reasonably provide the information. Finally, in a systematic manner, I outline the Chameleon software framework to integrate the analytical models with parameters specified by these three groups of stakeholders.Item Functional polymer/graphene oxide composites synthesis, characterization and applications(2016-08) Ha, Heonjoo; Ellison, Christopher J.; Willson, Carlton G; Freeman, Benny D; Akinwande, DejiPolymer nanocomposites have been identified as a growth area for the last several decades. The synergy between inorganic and organic compounds has played a major role in developing advanced functional materials for many emerging applications, including enhancing physical/chemical properties of base polymers, replacing metal counterparts, and introducing new energy storage materials, among others. While a number of carbon based nanoparticles have been considered as nanofiller material, significant research effort has been devoted to studies on graphene and its graphene oxide (GO) or reduced graphene oxide (rGO) derivatives. Graphenes are 2D sheets of carbonaceous material that possess extraordinary mechanical properties, thermal and electrical conductivities, and high surface area. However, most of the methods that have been developed to mass produce graphenes often require costly and tedious purification, along with associated high energy consumption, to achieve the most attractive forms of the material. One of the solutions to reduce the cost of synthesizing graphene while preserving its excellent properties is to use a precursor such as GO. While preparing GO, GO sheets can be functionalized with numerous reactive groups including carboxylic acids, hydroxyls, and epoxides that can be exploited for materials design. The work in this thesis outlines the synthesis of functional polymer/GO composites by utilizing secondary interactions, such as hydrogen bonding and π-π interactions, and covalent bonds between functional polymer and GO sheets. To understand the impact of these approaches, a fundamental investigation directed towards characterizing various chemical and physical properties for a range of GO-containing materials is discussed in full detail. In addition, different functional polymer/GO composites proposed in this work are evaluated for their utility in a number of different applications. Finally, it is expected that these composite materials will be cost-effective, commercially relevant and reasonable to scale-up for mass production. Therefore, this research will not only contribute to enriching fundamental knowledge but it also has potential to impact society and the economy.