Download or read book Cartesian Feedback Control for MRI Transmitter Array Systems written by Marta Gaia Zanchi and published by Stanford University. This book was released on 2010 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: Accurate control of the radio-frequency (RF) electromagnetic fields in Magnetic Resonance Imaging (MRI) is necessary to ensure patient safety and provide high-quality diagnostic capabilities. Precise control is however becoming increasingly difficult to achieve, given the recent trends toward high fields and transmitter array systems. At high fields, imaging is performed in a frequency regime where the wavelength is on the order of, or smaller than, the dimensions of the human body. This leads to prominent wave behavior, non-uniform field patterns, and increased power deposition. Multi-element transmitter array systems with independent phase and amplitude control of their elements support methods that can mitigate these problems. However, in turn, they demand high fidelity RF reproduction and may lead to undesired electromagnetic interactions between elements of the arrays and with interventional devices. Frequency-offset Cartesian feedback can be used to address all of these issues. In combination with the use of polyphase error amplifiers (to implement a low-IF control bandwidth), Cartesian feedback can be used with MRI power amplifiers and transmit coils to increase the fidelity of RF reproduction, without the in-bandwidth DC-offsets and quadrature mismatches that may lead to imaging artifacts such as bright spots and ghosting. In addition, the control system, which includes autotuning circuitry for stability and vector multipliers circuitry for feedback manipulation, can be used to tune the series output impedance of these amplifiers, thereby reducing the likelihood of interactions between elements of transmit array systems. Furthermore, a miniaturized variation of the control system (called Active Cable Trap) can be used on guidewires to suppress undesired currents elicited by coupling with the RF fields of the transmit coils. In an era of rapid progress in high field MRI for clinical applications, the frequency offset Cartesian feedback method and system thus promises to address many of the challenges faced by designers of multi-element transmitter array systems.
Download or read book Issues in Electronic Circuits Devices and Materials 2011 Edition written by and published by ScholarlyEditions. This book was released on 2012-01-09 with total page 2454 pages. Available in PDF, EPUB and Kindle. Book excerpt: Issues in Electronic Circuits, Devices, and Materials: 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Electronic Circuits, Devices, and Materials. The editors have built Issues in Electronic Circuits, Devices, and Materials: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Electronic Circuits, Devices, and Materials in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Electronic Circuits, Devices, and Materials: 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Download or read book Neural Metabolism In Vivo written by In-Young Choi and published by Springer Science & Business Media. This book was released on 2012-03-14 with total page 1168 pages. Available in PDF, EPUB and Kindle. Book excerpt: From the preface: “Neural Metabolism In Vivo aims to provide a comprehensive overview of neurobiology by presenting the basic principles of up-to-date and cutting-edge technology, as well as their application in assessing the functional, morphological and metabolic aspects of the brain. Investigation of neural activity of the living brain via neurovascular coupling using multimodal imaging techniques extended our understanding of fundamental neurophysiological mechanisms, regulation of cerebral blood flow in connection to neural activity and the interplay between neurons, astrocytes and blood vessels. Constant delivery of glucose and oxygen for energy metabolism is vital for brain function, and the physiological basis of neural activity can be assessed through measurements of cerebral blood flow and consumption of glucose and oxygen.... This book presents the complex physiological and neurochemical processes of neural metabolism and function in response to various physiological conditions and pharmacological stimulations. Neurochemical detection technologies and quantitative aspects of monitoring cerebral energy substrates and other metabolites in the living brain are described under the “Cerebral metabolism of antioxidants, osmolytes and others in vivo” section. Altogether, the advent of new in vivo tools has transformed neuroscience and neurobiology research, and demands interdisciplinary approaches as each technology could only approximate a very small fraction of the true complexity of the underlying biological processes. However, translational values of the emerging in vivo methods to the application of preclinical to clinical studies cannot be emphasized enough. Thus, it is our hope that advances in our understanding of biochemical, molecular, functional and physiological processes of the brain could eventually help people with neurological problems, which are still dominated by the unknowns.” -- In-Young Choi and Rolf Gruetter
Download or read book Novel MRI Technologies for Structural and Functional Imaging of Tissues with Ultra short T Values written by Oezen, Ali Caglar and published by KIT Scientific Publishing. This book was released on 2017-06-30 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: Conventional MRI has several limitations such as long scan durations, motion artifacts, very loud acoustic noise, signal loss due to short relaxation times, and RF induced heating of electrically conducting objects. The goals of this work are to evaluate and improve the state-of-the-art methods for MRI of tissue with short T?, to prove the feasibility of in vivo Concurrent Excitation and Acquisition, and to introduce simultaneous electroglottography measurement during functional lung MRI.
Download or read book RF Current Source Drive and Decoupling Technique for Parallel Transmit Arrays in Magnetic Resonance Imaging written by Won-Je Lee and published by . This book was released on 2008 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electrical Electronics Abstracts written by and published by . This book was released on 1997 with total page 2240 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Science Abstracts written by and published by . This book was released on 1993 with total page 948 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book MRI from Picture to Proton written by Donald W. McRobbie and published by Cambridge University Press. This book was released on 2017-04-13 with total page 405 pages. Available in PDF, EPUB and Kindle. Book excerpt: MR is a powerful modality. At its most advanced, it can be used not just to image anatomy and pathology, but to investigate organ function, to probe in vivo chemistry, and even to visualise the brain thinking. However, clinicians, technologists and scientists struggle with the study of the subject. The result is sometimes an obscurity of understanding, or a dilution of scientific truth, resulting in misconceptions. This is why MRI from Picture to Proton has achieved its reputation for practical clarity. MR is introduced as a tool, with coverage starting from the images, equipment and scanning protocols and traced back towards the underlying physics theory. With new content on quantitative MRI, MR safety, multi-band excitation, Dixon imaging, MR elastography and advanced pulse sequences, and with additional supportive materials available on the book's website, this new edition is completely revised and updated to reflect the best use of modern MR technology.
Download or read book RF Coils for MRI written by J. Thomas Vaughan and published by John Wiley & Sons. This book was released on 2012-12-19 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The content of this volume has been added to eMagRes (formerly Encyclopedia of Magnetic Resonance) - the ultimate online resource for NMR and MRI. To date there is no single reference aimed at teaching the art of applications guided coil design for use in MRI. This RF Coils for MRI handbook is intended to become this reference. Heretofore, much of the know-how of RF coil design is bottled up in various industry and academic laboratories around the world. Some of this information on coil technologies and applications techniques has been disseminated through the literature, while more of this knowledge has been withheld for competitive or proprietary advantage. Of the published works, the record of technology development is often incomplete and misleading, accurate referencing and attribution assignment being tantamount to admission of patent infringement in the commercial arena. Accordingly, the literature on RF coil design is fragmented and confusing. There are no texts and few courses offered to teach this material. Mastery of the art and science of RF coil design is perhaps best achieved through the learning that comes with a long career in the field at multiple places of employment...until now. RF Coils for MRI combines the lifetime understanding and expertise of many of the senior designers in the field into a single, practical training manual. It informs the engineer on part numbers and sources of component materials, equipment, engineering services and consulting to enable anyone with electronics bench experience to build, test and interface a coil. The handbook teaches the MR system user how to safely and successfully implement the coil for its intended application. The comprehensive articles also include information required by the scientist or physician to predict respective experiment or clinical performance of a coil for a variety of common applications. It is expected that RF Coils for MRI becomes an important resource for engineers, technicians, scientists, and physicians wanting to safely and successfully buy or build and use MR coils in the clinic or laboratory. Similarly, this guidebook provides teaching material for students, fellows and residents wanting to better understand the theory and operation of RF coils. Many of the articles have been written by the pioneers and developers of coils, arrays and probes, so this is all first hand information! The handbook serves as an expository guide for hands-on radiologists, radiographers, physicians, engineers, medical physicists, technologists, and for anyone with interests in building or selecting and using RF coils to achieve best clinical or experimental results. About EMR Handbooks / eMagRes Handbooks The Encyclopedia of Magnetic Resonance (up to 2012) and eMagRes (from 2013 onward) publish a wide range of online articles on all aspects of magnetic resonance in physics, chemistry, biology and medicine. The existence of this large number of articles, written by experts in various fields, is enabling the publication of a series of EMR Handbooks / eMagRes Handbooks on specific areas of NMR and MRI. The chapters of each of these handbooks will comprise a carefully chosen selection of articles from eMagRes. In consultation with the eMagRes Editorial Board, the EMR Handbooks / eMagRes Handbooks are coherently planned in advance by specially-selected Editors, and new articles are written (together with updates of some already existing articles) to give appropriate complete coverage. The handbooks are intended to be of value and interest to research students, postdoctoral fellows and other researchers learning about the scientific area in question and undertaking relevant experiments, whether in academia or industry. Have the content of this Handbook and the complete content of eMagRes at your fingertips! Visit: www.wileyonlinelibrary.com/ref/eMagRes View other eMagRes publications here
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1986 with total page 652 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Engineering Index Annual written by and published by . This book was released on 1992 with total page 2264 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since its creation in 1884, Engineering Index has covered virtually every major engineering innovation from around the world. It serves as the historical record of virtually every major engineering innovation of the 20th century. Recent content is a vital resource for current awareness, new production information, technological forecasting and competitive intelligence. The world?s most comprehensive interdisciplinary engineering database, Engineering Index contains over 10.7 million records. Each year, over 500,000 new abstracts are added from over 5,000 scholarly journals, trade magazines, and conference proceedings. Coverage spans over 175 engineering disciplines from over 80 countries. Updated weekly.
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 974 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Introduction to Embedded Systems Second Edition written by Edward Ashford Lee and published by MIT Press. This book was released on 2017-01-06 with total page 562 pages. Available in PDF, EPUB and Kindle. Book excerpt: An introduction to the engineering principles of embedded systems, with a focus on modeling, design, and analysis of cyber-physical systems. The most visible use of computers and software is processing information for human consumption. The vast majority of computers in use, however, are much less visible. They run the engine, brakes, seatbelts, airbag, and audio system in your car. They digitally encode your voice and construct a radio signal to send it from your cell phone to a base station. They command robots on a factory floor, power generation in a power plant, processes in a chemical plant, and traffic lights in a city. These less visible computers are called embedded systems, and the software they run is called embedded software. The principal challenges in designing and analyzing embedded systems stem from their interaction with physical processes. This book takes a cyber-physical approach to embedded systems, introducing the engineering concepts underlying embedded systems as a technology and as a subject of study. The focus is on modeling, design, and analysis of cyber-physical systems, which integrate computation, networking, and physical processes. The second edition offers two new chapters, several new exercises, and other improvements. The book can be used as a textbook at the advanced undergraduate or introductory graduate level and as a professional reference for practicing engineers and computer scientists. Readers should have some familiarity with machine structures, computer programming, basic discrete mathematics and algorithms, and signals and systems.
Download or read book Principles of Modern Radar written by Mark A. Richards and published by SciTech Publishing. This book was released on 2023-02-17 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Principles of Modern Radar: Basic Principles is a comprehensive text for courses in radar systems and technology, a professional training textbook for formal in-house courses and for new hires; a reference for ongoing study following a radar short course and a self-study and professional reference book.
Download or read book Electromagnetics and Antenna Technology written by Alan J. Fenn and published by Artech House. This book was released on 2017-12-31 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by a leading expert in the field, this practical new resource presents the fundamentals of electromagnetics and antenna technology. This book covers the design, electromagnetic simulation, fabrication, and measurements for various types of antennas, including impedance matching techniques and beamforming for ultrawideband dipoles, monopoles, loops, vector sensors for direction finding, HF curtain arrays, 3D printed nonplanar patch antenna arrays, waveguides for portable radar, reflector antennas, and other antennas. It explores the essentials of phased array antennas and includes detailed derivations of important field equations, and a detailed formulation of the method of moments. This resource exhibits essential derivations of equations, providing readers with a strong foundation of the underpinnings of electromagnetics and antennas. It includes a complete chapter on the details of antenna and electromagnetic test and measurement. This book explores details on 3D printed non-planar circular patch array antenna technology and the design and analysis of a planar array-fed axisymmetric gregorian reflector. The lumped-element impedance matched antennas are examined and include a look at an analytic impedance matching solution with a parallel LC network. This book provides key insight into many aspects of antenna technology that have broad applications in radar and communications.
Download or read book Microwave and RF Design written by Michael Bernard Steer and published by SciTech Publishing. This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Microwave & RF Design: A Systems Approach, 2nd Edition is a comprehensive treatment of the subject for advanced undergrad and graduate students (as well as professionals), focusing on the systems and emphasizing design. Components are covered in depth, but always with the idea of how they fit into modern radio, radar, and sensor systems. Advanced components and design techniques are presented along with a thoroughly modern treatment of traditional microwave theory and techniques."--pub. desc.
Download or read book Introduction to Radar Systems written by Merrill I. Skolnik and published by . This book was released on 1988 with total page 581 pages. Available in PDF, EPUB and Kindle. Book excerpt:
