3,691 research outputs found

    Takeuchi's Information Criteria as a form of Regularization

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    Takeuchi's Information Criteria (TIC) is a linearization of maximum likelihood estimator bias which shrinks the model parameters towards the maximum entropy distribution, even when the model is mis-specified. In statistical machine learning, L2L_2 regularization (a.k.a. ridge regression) also introduces a parameterized bias term with the goal of minimizing out-of-sample entropy, but generally requires a numerical solver to find the regularization parameter. This paper presents a novel regularization approach based on TIC; the approach does not assume a data generation process and results in a higher entropy distribution through more efficient sample noise suppression. The resulting objective function can be directly minimized to estimate and select the best model, without the need to select a regularization parameter, as in ridge regression. Numerical results applied to a synthetic high dimensional dataset generated from a logistic regression model demonstrate superior model performance when using the TIC based regularization over a L1L_1 and a L2L_2 penalty term

    Performance Monitoring of Control Systems using Likelihood Methods

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    Evaluating deterioration in performance of control systems using closed loop operating data is addressed. A framework is proposed in which acceptable performance is expressed as constraints on the closed loop transfer function impulse response coefficients. Using likelihood methods, a hypothesis test is outlined to determine if control deterioration has occurred. The method is applied to a simulation example as well as data from an operational distillation column, and the results are compared to those obtained using minimum variance estimation approaches

    Optimal and Robust Design of Integrated Control and Diagnostic Modules

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    The problem of designing an integrated control and diagnostic module is considered. The four degree of freedom controller is recast into a general framework wherein results from optimal and robust control theory can be easily implemented. For the case of an H2 objective, it is shown that the optimal control-diagnostic module involves constructing an optimal controller, closing the loop with this controller, and then designing an optimal diagnostic module for the closed loop. When uncertain plants are involved, this two-step method does not lead to reasonable diagnostics, and the control and diagnostic modules must be synthesized simultaneously. An example shows how this design can be accomplished with available methods

    "Food Ethics and Religion"

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    How does an engagement with religious traditions (broadly construed) illuminate and complicate the task of thinking through the ethics of eating? In this introduction, we survey some of the many food ethical issues that arise within various religious traditions and also consider some ethical positions that such traditions take on food. To say the least, we do not attempt to address all the ethical issues concerning food that arise in religious contexts, nor do we attempt to cover every tradition’s take on food. We look at just a few traditions and a few interesting writings on food ethics and religion: What do they say about the ethics of eating? Why do they say these things? Here we use the terms “food ethics” and “religion” ecumenically as big tents under which many importantly different sorts of things may be grouped. Among the wide range of food ethical issues we consider in this chapter, for example, are religious views about the ethics of keeping, hurting, and killing animals, killing plants, dominion over creation, wastefulness, purity, blessing, atonement, and the connection between food and character. We realize, moreover, that it might be a stretch to label some of the views engaged by selected readings in this chapter as “religious” on a stringent understanding of that term; Lisa Kemmerer’s “Indigenous Traditions,” for instance, addresses some views that are recognizably spiritual but perhaps not religious in a strict sense. We hope that our ecumenical usage of the term can bring these important traditions to bear on the discussion without reducing them to something they are not

    Solar Furnace: Heliostat and Concentrator Design

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    In recent decades, solar energy has been shown as a viable, clean, and abundant alternative to fossil fuels. Many methods of solar energy collection are being researched, with solar thermal electrochemistry being one of the most promising. Solar thermal electrochemistry uses sunlight to heat a furnace to temperatures nearing 2000 K. At these temperatures, metallic oxides can be decomposed to metals and oxygen with minimal electrical work. Achieving these high temperatures requires a solar furnace that consists of a heliostat to track and reflect the sun’s rays into a concentrator, which then focuses the sunlight to a single point in a solar thermal chemical reactor. A system of louvers regulates the amount of sunlight entering the system. Our research focuses on the design and development of the solar furnace components; specifically, the design and construction of the heliostat structure, the heliostat control system, and the concentrator

    Swiping without Sluicing

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    In English, when a question involving a prepositional wh-phrase (wh-PP) undergoes sluicing, the wh-word may be inverted around the preposition, in a process known as \u27swiping\u27. I show, contrary to previous work, that swiping is not restricted to sluicing contexts: it is also permitted when the inverted wh-PP is coordinated with another wh-phrase (e.g., When and who by was this first discovered? ). I argue that English syntax is able to generate swiped structures in all questions involving wh-PPs, including \u27simple\u27 (non-sluiced, non-coordinated) wh-questions. Swiping in simple wh-questions is subsequently ruled out on prosodic grounds. The account crucially relies on coordinated wh-questions having the same prosodic signature as Right Node Raising constructions

    Avery Final Report: Identification and Cross-Directional Control of Coating Processes

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    Coating refers to the covering of a solid with a uniform layer of liquid. Of special industrial interest is the cross-directional control of coating processes, where the cross-direction refers to the direction perpendicular to the substrate movement. The objective of the controller is to maintain a uniform coating under unmeasured process disturbances. Assumptions that are relevant to coating processes found in industry are used to develop a model for control design. We show how to identify the model from input-output data. This model is used to derive a model predictive controller to maintain flat profiles of coating across the substrate by varying the liquid flows along the cross direction. The model predictive controller computes the control action which minimizes the predicted deviation in cross-directional uniformity. The predictor combines the estimate obtained from the model with the measurement of the cross-directional uniformity to obtain a prediction for the next time step. A filter is used to obtain robustness to model error and insensitivity to measurement noise. The tuning of the noise filter and different methods for handling actuator constraints are studied in detail. The three different constraint-handling methods studied are: the weighting of actuator movements in the objective function, explicitly adding constraints to the control algorithm, i.e. constrained model predictive control, and scaling infeasible control actions calculated from an unconstrained control law to be feasible. Actuator constraints, measurement noise, model uncertainty, and the plant condition number are investigated to determine which of these limit the achievable closed loop performance. From knowledge of how these limitations affect the performance we find how the plant could be modified to improve the process uniformity. Also, because identification of model parameters is time-consuming and costly, we study how accurate the identification must be to achieve a given level of performance. The theory developed throughout the paper is rigorously verified though simulations and experiments on a pilot plant. The effect of interactions on the closed loop performance is shown to be negligible for this pilot plant. The measurement noise and the actuator constraints are shown to have the largest effect on closed loop performance

    Northwest Semitic Epigraphy and Historicity in the Book of Jeremiah

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    This thesis examines recent finds in Northwest Semitic epigraphy in an effort to determine their effectiveness for speaking to the historical validity of the prose sections of the Book of Jeremiah. In light of the book’s complex compositional issues, many models for understanding its development have been published over the last century; one foundational theory, expounded primarily by Robert P. Carroll, argues that material in Jeremiah apart from chapters 2–26 (Source A) fail to provide an accurate picture of the Historical Jeremiah. This claim is examined in light of Hebrew epigraphy. Chapter one introduces the issues involved in the study while chapter two provides an assessment and history of, as well as a limited response to, the views mentioned above. Chapters three and four examine relevant Semitic epigraphy, including onomastic evidence, and highlight potential correspondences with the Book of Jeremiah. Chapter five is a summary and conclusion of the study, relating each point to the original issue posed by Carroll and others. The position defended in this work is that Northwest Semitic epigraphy, though limited with regards to some redactional issues, is generally relevant to the discussion of the historicity Jeremianic prose, namely in the way it fits the historical context of the late seventh and early sixth centuries BCE. It is concluded that onomastic evidence provides the greatest support for historicity of the biographical narratives in Jeremiah on the basis of strong correspondence with data from the epigraphic record

    A modeling-based assessment of acousto-optic sensing for monitoring high-intensity focused ultrasound lesion formation

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    Real-time acousto-optic (AO) sensing - a dual-wave modality that combines ultrasound with diffuse light to probe the optical properties of turbid media - has been demonstrated to non-invasively detect changes in ex vivo tissue optical properties during high-intensity focused ultrasound (HIFU) exposure. The AO signal indicates the onset of lesion formation and predicts resulting lesion volumes. Although proof-of-concept experiments have been successful, many of the underlying parameters and mechanisms affecting thermally induced optical property changes and the AO detectability of HIFU lesion formation are not well understood. In thesis, a numerical simulation was developed to model the AO sensing process and capture the relevant acoustic, thermal, and optical transport processes. The simulation required data that described how optical properties changed with heating. Experiments were carried out where excised chicken breast was exposed to thermal bath heating and changes in the optical absorption and scattering spectra (500 nm - 1100 nm) were measured using a scanning spectrophotometer and an integrating sphere assembly. Results showed that the standard thermal dose model currently used for guiding HIFU treatments needs to be adjusted to describe thermally induced optical property changes. To model the entire AO process, coupled models were used for ultrasound propagation, tissue heating, and diffusive light transport. The angular spectrum method was used to model the acoustic field from the HIFU source. Spatial-temporal temperature elevations induced by the absorption of ultrasound were modeled using a finite-difference time-domain solution to the Pennes bioheat equation. The thermal dose model was then used to determine optical properties based on the temperature history. The diffuse optical field in the tissue was then calculated using a GPU-accelerated Monte Carlo algorithm, which accounted for light-sound interactions and AO signal detection. The simulation was used to determine the optimal design for an AO guided HIFU system by evaluating the robustness of the systems signal to changes in tissue thickness, lesion optical contrast, and lesion location. It was determined that AO sensing is a clinically viable technique for guiding the ablation of large volumes and that real-time sensing may be feasible in the breast and prostate
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