Author
Ephraim M Sparrow
Other affiliations: National Science Foundation, University of Illinois at Chicago, University of Texas at Arlington ...read more
Bio: Ephraim M Sparrow is an academic researcher from University of Minnesota. The author has contributed to research in topics: Heat transfer & Heat transfer coefficient. The author has an hindex of 77, co-authored 552 publications receiving 27226 citations. Previous affiliations of Ephraim M Sparrow include National Science Foundation & University of Illinois at Chicago.
Papers published on a yearly basis
Papers
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TL;DR: In this article, a rotating fan simulation, which takes full account of the rotation of the fan blades and of the true nature of the delivered flow, was implemented with high fidelity.
11 citations
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TL;DR: In this article, the axial distribution of the heat transfer coefficient downstream of an abrupt contraction in a flat rectangular duct was investigated, where the contraction was created by the presence of a forward-facing step in one of the walls of the duct.
Abstract: Experiments were performed to investigate the axial distribution of the heat transfer coefficient downstream of an abrupt contraction in a flat rectangular duct. The contraction was created by the presence of a forward-facing step in one of the walls of the duct. The flow arriving at the step was hydrodynamically developed and isothermal. In the contracted duct, the duct wall that constituted the continuation of the step was maintained at a uniform temperature different from that of the entering flow, while the other walls were adiabatic. During the course of the experiments, the Reynolds number of the flow in the contracted duct ranged from 4,000 to 24,000, while the ratio of the post-contraction to the precontraction duct heights took on values of 1 (no contraction), 0.8, 0.6, and 0.4. In the presence of the contraction, the axial distribution of the Sherwood number increased at first, attained a maximum, and then decreased monotonically to a fully developed value. In contrast, the no-contraction Sherwood number decreased monotonically and subsequently became fully developed. At a given Reynolds number, the peak Sherwood number for the contraction case was virtually independent of the contraction ratio and exceeded the largest measured Sherwood number for the no-contractionmore » case by about a factor of two.« less
11 citations
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TL;DR: In this article, a broad ranging study of the fluid flow in packed beds of uniform diameter spheres has been implemented by the method of numerical simulation, which encompassed both laminar and turbulent flows, random and regular packings of the spheres, bed containments in both rectangular ducts and circular pipes, and beds of either bounded or unbounded lateral extent.
11 citations
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01 Jan 2019TL;DR: In this article, an extensive review of the literature is presented and brought together in a single repository to answer some critical issues such as: which CFD models are most able to calculate fluid drag and heat transfer between the fluid and the cylinder, what are the mesh requirements for hydrodynamic and thermal analysis, how important is the blockage effect for cylinders that are placed in confined spaces (such as wind tunnels), Do upstream effects significantly alter the results, and what aspect ratio is sufficient for a three-dimensional prism to approximate a two-dimensional square cylinder?
Abstract: The canonical problem of flow over a square cylinder has been studied extensively in the scientific literature. Nevertheless, there are some critical issues which are not fully understood. Here, an extensive review of the literature is presented and brought together in a single repository. Next, remaining questions are identified such as: Which CFD models are most able to calculate fluid drag and heat transfer between the fluid and the cylinder? What are the mesh requirements for hydrodynamic and thermal analysis? How important is the blockage effect for cylinders that are placed in confined spaces (such as wind tunnels)? Do upstream effects significantly alter the results (such as upstream flow development, velocity profile, and turbulence intensity)? What aspect ratio is sufficient for a three-dimensional prism to approximate a two-dimensional square cylinder? Finally, how do three-dimensional flow patterns differ from those in two-dimensions? This manuscript attempts to answer these questions and provide practical recommendations to academic and industrial scientists. One key result from this work is the development of new correlating equations for both the drag coefficient and the Nusselt number for a wide range of Reynolds numbers and thermal conditions. The results presented here agree very well with accepted correlations from the literature, however these new correlations cover a much wider range of Reynolds numbers than previously published correlating equations.
11 citations
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TL;DR: A synergistic investigation involving both experiment and numerical simulation was performed in vitro to determine the heat flow from rechargeable neuromodulation systems into surrounding media and found that for both components of MDT, substantially lower rates of heat flow were produced compared with those for ANS and BSC.
Abstract: A synergistic investigation involving both experiment and numerical simulation was performed in vitro to determine the heat flow from rechargeable neuromodulation systems into surrounding media. Each system consists of an implant and an external recharging antenna, and the heat flows of each of these components were determined separately. Three systems, each produced by a different medical device firm, were evaluated. The evaluated products included those from Medtronic Inc. (MDT), ANS (a St. Jude Company), and the Boston Scientific Company (BSC, formerly Advanced Bionics). To ensure statistical significance, three nominally identical samples of each of the three systems were included in the study. Furthermore, for each sample of each system, replicate evaluations were performed for both the implant and the antenna. It was found that for both components of MDT, substantially lower rates of heat flow were produced compared with those for ANS and BSC. With regard to the latter systems, the higher rates of heat flow were not consistently ordered for the implant and for the antenna. In general, replicate data runs for each system and each component were in satisfactory agreement. The different samples of the MDT system showed only minor deviations with regard to heat flow. The deviations among the different samples of both ANS and BSC were larger than those evidenced for MDT.
11 citations
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TL;DR: A comprehensive review of spatiotemporal pattern formation in systems driven away from equilibrium is presented in this article, with emphasis on comparisons between theory and quantitative experiments, and a classification of patterns in terms of the characteristic wave vector q 0 and frequency ω 0 of the instability.
Abstract: A comprehensive review of spatiotemporal pattern formation in systems driven away from equilibrium is presented, with emphasis on comparisons between theory and quantitative experiments. Examples include patterns in hydrodynamic systems such as thermal convection in pure fluids and binary mixtures, Taylor-Couette flow, parametric-wave instabilities, as well as patterns in solidification fronts, nonlinear optics, oscillatory chemical reactions and excitable biological media. The theoretical starting point is usually a set of deterministic equations of motion, typically in the form of nonlinear partial differential equations. These are sometimes supplemented by stochastic terms representing thermal or instrumental noise, but for macroscopic systems and carefully designed experiments the stochastic forces are often negligible. An aim of theory is to describe solutions of the deterministic equations that are likely to be reached starting from typical initial conditions and to persist at long times. A unified description is developed, based on the linear instabilities of a homogeneous state, which leads naturally to a classification of patterns in terms of the characteristic wave vector q0 and frequency ω0 of the instability. Type Is systems (ω0=0, q0≠0) are stationary in time and periodic in space; type IIIo systems (ω0≠0, q0=0) are periodic in time and uniform in space; and type Io systems (ω0≠0, q0≠0) are periodic in both space and time. Near a continuous (or supercritical) instability, the dynamics may be accurately described via "amplitude equations," whose form is universal for each type of instability. The specifics of each system enter only through the nonuniversal coefficients. Far from the instability threshold a different universal description known as the "phase equation" may be derived, but it is restricted to slow distortions of an ideal pattern. For many systems appropriate starting equations are either not known or too complicated to analyze conveniently. It is thus useful to introduce phenomenological order-parameter models, which lead to the correct amplitude equations near threshold, and which may be solved analytically or numerically in the nonlinear regime away from the instability. The above theoretical methods are useful in analyzing "real pattern effects" such as the influence of external boundaries, or the formation and dynamics of defects in ideal structures. An important element in nonequilibrium systems is the appearance of deterministic chaos. A greal deal is known about systems with a small number of degrees of freedom displaying "temporal chaos," where the structure of the phase space can be analyzed in detail. For spatially extended systems with many degrees of freedom, on the other hand, one is dealing with spatiotemporal chaos and appropriate methods of analysis need to be developed. In addition to the general features of nonequilibrium pattern formation discussed above, detailed reviews of theoretical and experimental work on many specific systems are presented. These include Rayleigh-Benard convection in a pure fluid, convection in binary-fluid mixtures, electrohydrodynamic convection in nematic liquid crystals, Taylor-Couette flow between rotating cylinders, parametric surface waves, patterns in certain open flow systems, oscillatory chemical reactions, static and dynamic patterns in biological media, crystallization fronts, and patterns in nonlinear optics. A concluding section summarizes what has and has not been accomplished, and attempts to assess the prospects for the future.
6,145 citations
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TL;DR: The use of a latent heat storage system using phase change materials (PCMs) is an effective way of storing thermal energy and has the advantages of high energy storage density and the isothermal nature of the storage process.
Abstract: The use of a latent heat storage system using phase change materials (PCMs) is an effective way of storing thermal energy and has the advantages of high-energy storage density and the isothermal nature of the storage process. PCMs have been widely used in latent heat thermal-storage systems for heat pumps, solar engineering, and spacecraft thermal control applications. The uses of PCMs for heating and cooling applications for buildings have been investigated within the past decade. There are large numbers of PCMs that melt and solidify at a wide range of temperatures, making them attractive in a number of applications. This paper also summarizes the investigation and analysis of the available thermal energy storage systems incorporating PCMs for use in different applications.
4,482 citations
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01 Jan 1996TL;DR: The client would like to get a larger, approximately 3 cm in diameter, well fixed tissue sample, together with a detailed report of the clinical presentation, gross, and microscopic lesions, along with the submission of samples prepared in a similar manner by the client for processing.
Abstract: We wrote it to be read by, and taught to, senior undergraduates and starting graduate students, rather than studied in a research laboratory. We wrote it using the same style and sentence construction that we have used in countless classroom lectures, rather than how we have written our countless (and much-less read) formal scientificpapers. In this respect particularly, wehave been deliberate in notreferencing the sources of every experimental fact or theoretical concept (although we do include some hints and clues in the chapters). However, at the end of each chapter we have included groups of references that should lead you to the best sources in the literature and help you go into more depth as you become more confident about what you are looking for. We are great believers in the value of history as the basis for under- standing the present and so the history of the techniques and key historical references are threaded throughout the book. Just because a reference is dated in the previous century (or even the antepenultimate century) doesn’t mean it isn’t useful! Likewise, with the numerous figures drawn from across the fields of materials science and engineering and nanotechnology, we do not reference the source in each caption. But at the very end of the book each of our many generous colleagues whose work we have used is clearly acknowledged.
4,412 citations
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30 Sep 2010
TL;DR: Computer Vision: Algorithms and Applications explores the variety of techniques commonly used to analyze and interpret images and takes a scientific approach to basic vision problems, formulating physical models of the imaging process before inverting them to produce descriptions of a scene.
Abstract: Humans perceive the three-dimensional structure of the world with apparent ease. However, despite all of the recent advances in computer vision research, the dream of having a computer interpret an image at the same level as a two-year old remains elusive. Why is computer vision such a challenging problem and what is the current state of the art? Computer Vision: Algorithms and Applications explores the variety of techniques commonly used to analyze and interpret images. It also describes challenging real-world applications where vision is being successfully used, both for specialized applications such as medical imaging, and for fun, consumer-level tasks such as image editing and stitching, which students can apply to their own personal photos and videos. More than just a source of recipes, this exceptionally authoritative and comprehensive textbook/reference also takes a scientific approach to basic vision problems, formulating physical models of the imaging process before inverting them to produce descriptions of a scene. These problems are also analyzed using statistical models and solved using rigorous engineering techniques Topics and features: structured to support active curricula and project-oriented courses, with tips in the Introduction for using the book in a variety of customized courses; presents exercises at the end of each chapter with a heavy emphasis on testing algorithms and containing numerous suggestions for small mid-term projects; provides additional material and more detailed mathematical topics in the Appendices, which cover linear algebra, numerical techniques, and Bayesian estimation theory; suggests additional reading at the end of each chapter, including the latest research in each sub-field, in addition to a full Bibliography at the end of the book; supplies supplementary course material for students at the associated website, http://szeliski.org/Book/. Suitable for an upper-level undergraduate or graduate-level course in computer science or engineering, this textbook focuses on basic techniques that work under real-world conditions and encourages students to push their creative boundaries. Its design and exposition also make it eminently suitable as a unique reference to the fundamental techniques and current research literature in computer vision.
4,146 citations
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TL;DR: In this paper, a review of the history of thermal energy storage with solid-liquid phase change has been carried out and three aspects have been the focus of this review: materials, heat transfer and applications.
4,019 citations