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Author: Mats Sandberg Publisher: ISBN: 9789171110923 Category : Buildings Languages : en Pages : 36
Book Description
A supply of cold air from low velocity devices located at floor level creates a gravity current type of flow which means that the flow is governed by its negative buoyancy. The aim was to study properties of gravity currents at the conditions one has in room flow situations. Findings from both experimental work and numerical simulations are presented. The supply Archimedes number was varied within the limits one has in applications. Different shapes of terminals were tested. In the experimental work two approaches were used: (i) Scale model tests with water as operating fluid and density difference created by adding salt to the supply flow; (ii) Full scale tests in mock ups of real rooms. In the scale model both starting flow and stationary flows were studied. In a typical room flow situation with a supply device located at a wall the height of the gravity current after a some distance becomes nearly constant and the flow resembles subcritical radial flow. The decay of the velocity is then nearly inversely proportional to the distance r from the supply. The decay follows usually the relation r(-a) with 'a' varying between 0.8 to 1.3. For supply Archimedes numbers substantially greater than one there is an initial increase of the velocity and it reaches a maximum wherefrom it starts to decay. From the heat load and the width of the room the magnitude of the velocity in the room can be assessed. Two-dimensional supply at Archimedes number, Ar(s), greater than one gives rise to a critical flow with maximum velocity equal to B(1/3) (B is the specific buoyancy flux/unit width). The height, h, of the density current is equal to h/H = Ar(s)(-l /3) (H is the height of the supply device).
Author: Mats Sandberg Publisher: ISBN: 9789171110923 Category : Buildings Languages : en Pages : 36
Book Description
A supply of cold air from low velocity devices located at floor level creates a gravity current type of flow which means that the flow is governed by its negative buoyancy. The aim was to study properties of gravity currents at the conditions one has in room flow situations. Findings from both experimental work and numerical simulations are presented. The supply Archimedes number was varied within the limits one has in applications. Different shapes of terminals were tested. In the experimental work two approaches were used: (i) Scale model tests with water as operating fluid and density difference created by adding salt to the supply flow; (ii) Full scale tests in mock ups of real rooms. In the scale model both starting flow and stationary flows were studied. In a typical room flow situation with a supply device located at a wall the height of the gravity current after a some distance becomes nearly constant and the flow resembles subcritical radial flow. The decay of the velocity is then nearly inversely proportional to the distance r from the supply. The decay follows usually the relation r(-a) with 'a' varying between 0.8 to 1.3. For supply Archimedes numbers substantially greater than one there is an initial increase of the velocity and it reaches a maximum wherefrom it starts to decay. From the heat load and the width of the room the magnitude of the velocity in the room can be assessed. Two-dimensional supply at Archimedes number, Ar(s), greater than one gives rise to a critical flow with maximum velocity equal to B(1/3) (B is the specific buoyancy flux/unit width). The height, h, of the density current is equal to h/H = Ar(s)(-l /3) (H is the height of the supply device).
Author: Mat Santamouris Publisher: Routledge ISBN: 1136572392 Category : Technology & Engineering Languages : en Pages : 266
Book Description
Advances in Building Energy Research (ABER) offers state-of-the-art information on the environmental science and performance of buildings, linking new technologies and methodologies with the latest research on systems, simulations and standards. As stringently reviewed as a journal but with the breadth of a book, this annual volume brings together invited contributions from the foremost international experts on energy efficiency and environmental quality of buildings. Spanning a broad range of technical subjects, this is a 'must have' reference on global developments in the field, suitable for architects and building engineers, environmental engineers, industry professionals, students, teachers and researchers in building science, technical libraries and laboratories. Volume 3 covers: - Energy, Carbon and Cost Performance of Building Stocks - Solar Chimneys in Buildings - Optimization and Economics of Solar Cooling Systems - Artificial Neural Networks and Genetic Algorithms in Energy Applications in Buildings - Decision Support Methodologies on the Energy Efficiency and Energy Management in Buildings - Progress in Numerical Modelling for Urban Thermal Environment Studies - Post Occupancy Evaluation (POE): An Inevitable Step Toward Sustainability - Guidelines to Avoid Mould Growth in Buildings - Thermal Impact of Strategic Landscaping in Cities - Urban Heat Island and its Impact on Building Energy Consumption - Green Roofs in Buildings: Thermal and Environmental Behaviour - Building Earth-Contact Heat Transfer
Author: David Etheridge Publisher: ISBN: Category : Science Languages : en Pages : 760
Book Description
This book sets down the fundamentals of the theory and measurement of building ventilation and describes the various techniques for predicting and measuring ventilation. It addresses both envelope flows and internal air motion. The first part of the book is primarily concerned with physical descriptions and theoretical models: starting with an overview of the basic mechanisms and characteristics of envelope flows, it then addresses the treatment of the flow characteristics of individual openings and mathematical models for complete building envelopes. Theories for internal air motion are then discussed in detail: mechanisms of mass transport in terms of air motion and age distribution, primary air flows in isolation, resulting flows in enclosed spaces, and flows through large internal openings. The second part, concerned with measurement techniques both at full scale and at model scale, begins with techniques for determining flow characteristics of envelope openings. The use of tracer gases in the study of age distribution and ventilation efficiency is dealt with in detail. Scale modelling for investigating both envelope flows and internal motions is also addressed. The final chapter deals with Computational Fluid Dynamics, since one of its main applications is an alternative to conventional experimental techniques. Natural ventilation is re-emerging as an alternative to mechanical systems in some commercial buildings and both natural and mechanical ventilation are dealt with in detail.
Author: Shubham Tayal Publisher: John Wiley & Sons ISBN: 1394167628 Category : Technology & Engineering Languages : en Pages : 325
Book Description
ADVANCED ULTRA LOW-POWER SEMICONDUCTOR DEVICES Written and edited by a team of experts in the field, this important new volume broadly covers the design and applications of metal oxide semiconductor field effect transistors. This outstanding new volume offers a comprehensive overview of cutting-edge semiconductor components tailored for ultra-low power applications. These components, pivotal to the foundation of electronic devices, play a central role in shaping the landscape of electronics. With a focus on emerging low-power electronic devices and their application across domains like wireless communication, biosensing, and circuits, this book presents an invaluable resource for understanding this dynamic field. Bringing together experts and researchers from various facets of the VLSI domain, the book addresses the challenges posed by advanced low-power devices. This collaborative effort aims to propel engineering innovations and refine the practical implementation of these technologies. Specific chapters delve into intricate topics such as Tunnel FET, negative capacitance FET device circuits, and advanced FETs tailored for diverse circuit applications. Beyond device-centric discussions, the book delves into the design intricacies of low-power memory systems, the fascinating realm of neuromorphic computing, and the pivotal issue of thermal reliability. Authors provide a robust foundation in device physics and circuitry while also exploring novel materials and architectures like transistors built on pioneering channel/dielectric materials. This exploration is driven by the need to achieve both minimal power consumption and ultra-fast switching speeds, meeting the relentless demands of the semiconductor industry. The book’s scope encompasses concepts like MOSFET, FinFET, GAA MOSFET, the 5-nm and 7-nm technology nodes, NCFET, ferroelectric materials, subthreshold swing, high-k materials, as well as advanced and emerging materials pivotal for the semiconductor industry’s future.
Author: Publisher: Academic Press ISBN: 0080864384 Category : Technology & Engineering Languages : en Pages : 481
Book Description
Volume 41 includes an in-depth review of the most important, high-speed switches made with heterojunction technology. This volume is aimed at the graduate student or working researcher who needs a broad overview andan introduction to current literature. - The first complete review of InP-based HFETs and complementary HFETs, which promise very low power and high speed - Offers a complete, three-chapter review of resonant tunneling - Provides an emphasis on circuits as well as devices
Author: Nihal Kularatna Publisher: CRC Press ISBN: 0415802482 Category : Technology & Engineering Languages : en Pages : 414
Book Description
As we increasingly use electronic devices to direct our daily lives, so grows our dependence on reliable energy sources to power them. Because modern electronic systems demand steady, efficient, reliable DC voltage sources—often at a sub-1V level—commercial AC lines, batteries, and other common resources no longer suffice. New technologies also require intricate techniques to protect against natural and manmade disasters. Still, despite its importance, practical information on this critical subject remains hard to find. Using simple, accessible language to balance coverage of theoretical and practical aspects, DC Power Supplies, Power Management and Surge Protection details the essentials of power electronics circuits applicable to low-power systems, including modern portable devices. A summary of underlying principles and essential design points, it compares academic research and industry publications and reviews DC power supply fundamentals, including linear and low-dropout regulators. Content also addresses common switching regulator topologies, exploring resonant conversion approaches. Coverage includes other important topics such as: Control aspects and control theory Digital control and control ICs used in switching regulators Power management and energy efficiency Overall power conversion stage and basic protection strategies for higher reliability Battery management and comparison of battery chemistries and charge/discharge management Surge and transient protection of circuits designed with modern semiconductors based on submicron dimension transistors This specialized design resource explores applicable fundamental elements of power sources, with numerous cited references and discussion of commercial components and manufacturers. Regardless of their previous experience level, this information will greatly aid designers, researchers, and academics who, study, design, and produce the viable new power sources needed to propel our modern electronic world. CRC Press Authors Speak Nihal Kularatna introduces his book. Watch the video
Author: Anantha Chandrakasan Publisher: John Wiley & Sons ISBN: 0780334299 Category : Technology & Engineering Languages : en Pages : 656
Book Description
This collection of important papers provides a comprehensive overview of low-power system design, from component technologies and circuits to architecture, system design, and CAD techniques. LOW POWER CMOS DESIGN summarizes the key low-power contributions through papers written by experts in this evolving field.
Author: Mats Sandberg
Author: Mats Sandberg
Author: Mat Santamouris
Author: David Etheridge
Author: Shubham Tayal
Author: Institute for Research in Construction (Canada). Information Service
Author: 
Author: Nihal Kularatna
Author: Arijit Saha
Author: Anantha Chandrakasan
Author: