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.

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Pattern formation outside of equilibrium

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.

Review on thermal energy storage with phase change materials and applications

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.

Transmission Electron Microscopy

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.

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Computer Vision: Algorithms and Applications

Review on thermal energy storage with phase change: materials, heat transfer analysis and applications

This paper describes a three-part numerical investigation of fluid flow and heat transfer in a never-previously-studied pipe bend situation. The investigation deals with downstream fluid-flow and heat transfer processes which are affected by upstream flow disturbances. The studied physical situation is a 90° pipe bend fitted with a wall-adjacent obstruction that partially blocks the inlet cross section. The first phase of the work consisted of validating numerical simulation results with experimental data. In the second phase, the impact of the inlet flow distribution on the pressure drop is determined. Heat transfer downstream of the bend exit comprises the third section of the paper. The heat transfer results are reported in terms of the circumferentially averaged Nusselt numbers which are displayed as a function of axial position for Reynolds numbers between 100 and 10,000. It was found that the disturbances caused by the blockage significantly enhance the Nusselt number values.

In-bend pressure drop and post-bend heat transfer for a bend with a partial blockage at its inlet

Temperature recovery factors for flow longitudinal to a circular cylinder

Heat transfer in the separated region upstream of an orifice in a tube

Purpose




The study described here aims to set forth an analysis approach for a specific biomedical therapeutic device principally involving fluid mechanics and resulting sound generation. The function of the therapeutic device is to clear mucus from the airways of the lungs. Clearance of the airways is a primary means of relief for cystic fibrosis and is also effective in less profound dysfunctions such as asthma. The complete system consists of a device to periodically pulse air pressure and a vest that girdles the abdomen of the patient and receives and discharges the pulsating airflow. The source of pulsed air can be tuned both with respect to the amplitude and frequency of the pressure pulsations.




Design/methodology/approach




The key design tools used here are computational fluid dynamics and the theory of turbulence-based sound generation. The fluid flow inside of the device is multidimensional, unsteady and turbulent.




Findings




Results provided by the fluid mechanic study include the rates of fluid flow between the device and the inflatable vest, the rates of air supplied to and extracted from the device, the fluid velocity magnitudes and directions that result from the geometry of the device and the magnitude of the turbulence generated by the fluid motion and the rotating component of the device. Both the velocity magnitudes and the strength of the turbulence contribute to the quantitative evaluation of the sound generation.




Originality/value




A comprehensive literature search on this type of therapeutic device to clear mucus from the airways of the lungs revealed no previous analysis of the fluid flow and sound generation inside of the device producing the pulsed airflow. The results presented in this paper pinpoint the locations and causes of sound generation that can cause audible discomfort for patients.

Fluid mechanics and sound generation for lung-clearance therapy: advanced design modality for a biomedical therapeutic device

A finite-difference marching scheme was employed to obtain numerical solutions for a wall plume spawned by the discharge from a vertical, natural convection channel flow. The plume is bounded by an isothermal vertical wall that is the continuation of one of the walls of the channel. The wall-plume solutions were carried out for a range of dimensionless heights of the channel and for a Prandtl number of 0.7. Since the channel height controls the velocity and temperature profiles at the channel exit, it also plays a key role in the development of the wall plume because these profiles serve to initiate the plume. Just downstream of the channel exit, the newly exposed flank of the plume interacts with and is cooled by the ambient fluid, while the wall-adjacent portion of the plume retains its channel heritage. Subsequently, the ambient fluid penetrates deeply into the plume, effectively obliterating its channel origins. Thereafter, the plume approaches a natural convection vertical-plate boundary lay...

Ephraim M Sparrow

Papers

In-bend pressure drop and post-bend heat transfer for a bend with a partial blockage at its inlet

Temperature recovery factors for flow longitudinal to a circular cylinder

Heat transfer in the separated region upstream of an orifice in a tube

Fluid mechanics and sound generation for lung-clearance therapy: advanced design modality for a biomedical therapeutic device

a Wall Plume Fed by the Discharge of a Vertical Channel