A General Purpose Computational Approach to the Design of Gradient Coils for Arbitrary Geometries PDF Download
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Author:
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ISBN:
Category : Magnetic resonance imaging
Languages : en
Pages : 328
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Book Description
Abstract: This research concentrates on two major engineering areas associated with biomedical instrumentation that have recently gained significant academic and industrial interest: the gradient coil design for Magnetic Resonance Imaging (MRI) and the high frequency full-wave field simulations with the Method of Moments (MoM). A new computational approach to the design of gradient coils for magnetic resonance imaging is introduced. The theoretical formulation involves a constrained cost function between the desired field in a particular region of interest in space and the current-carrying coil plane. Based on Biot-Savart's integral equation, an appropriate weight function is introduced in conjunction with linear approximation functions. This permits the transformation of the problem formulation into a linear matrix equation whose solution yields discrete current elements in terms of magnitude and direction within a specified coil plane. These current elements can be synthesized into practical wire configuration by suitably combining the individual wire loops. Numerical predictions and measurements underscore the success of this approach in terms of achieving a highly linear field while maintaining low parasitic fields, low inductance and a sufficient degree of shielding. Experimental results confirm the field predictions of the computational approach. Extending the numerical modeling efforts to dynamic phenomena, a novel MoM formulation permits the computation of electromagnetic fields in conductive surfaces and in three-dimensional biological bodies. The excitation can be provided with current loops, voltage sources, or an incident electromagnetic wave. This method enables us to solve a broad spectrum of problems arising in MRI: full-wave RF coil simulations, eddy currents predictions in the magnet bore, and induced currents in the biological body. Surfaces are represented as triangles and the three-dimensional bodies are subdivided into tetrahedra. This numerical discretization methodology makes the approach very flexible to handle a wide range of practical coil geometries. Specifically, in this thesis the MoM is employed to study the effect of switching gradient coils in the presence of a biological load.
Author:
Publisher:
ISBN:
Category : Magnetic resonance imaging
Languages : en
Pages : 328
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Book Description
Abstract: This research concentrates on two major engineering areas associated with biomedical instrumentation that have recently gained significant academic and industrial interest: the gradient coil design for Magnetic Resonance Imaging (MRI) and the high frequency full-wave field simulations with the Method of Moments (MoM). A new computational approach to the design of gradient coils for magnetic resonance imaging is introduced. The theoretical formulation involves a constrained cost function between the desired field in a particular region of interest in space and the current-carrying coil plane. Based on Biot-Savart's integral equation, an appropriate weight function is introduced in conjunction with linear approximation functions. This permits the transformation of the problem formulation into a linear matrix equation whose solution yields discrete current elements in terms of magnitude and direction within a specified coil plane. These current elements can be synthesized into practical wire configuration by suitably combining the individual wire loops. Numerical predictions and measurements underscore the success of this approach in terms of achieving a highly linear field while maintaining low parasitic fields, low inductance and a sufficient degree of shielding. Experimental results confirm the field predictions of the computational approach. Extending the numerical modeling efforts to dynamic phenomena, a novel MoM formulation permits the computation of electromagnetic fields in conductive surfaces and in three-dimensional biological bodies. The excitation can be provided with current loops, voltage sources, or an incident electromagnetic wave. This method enables us to solve a broad spectrum of problems arising in MRI: full-wave RF coil simulations, eddy currents predictions in the magnet bore, and induced currents in the biological body. Surfaces are represented as triangles and the three-dimensional bodies are subdivided into tetrahedra. This numerical discretization methodology makes the approach very flexible to handle a wide range of practical coil geometries. Specifically, in this thesis the MoM is employed to study the effect of switching gradient coils in the presence of a biological load.
Author: Elmar Laistler
Publisher: Frontiers Media SA
ISBN: 2832502970
Category : Science
Languages : en
Pages : 168
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Book Description
Author:
Publisher:
ISBN:
Category : Physics
Languages : en
Pages : 888
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Book Description
Author: Pierre-Marie Robitaille
Publisher: Springer Science & Business Media
ISBN: 0387496483
Category : Medical
Languages : en
Pages : 487
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Book Description
The foundation for understanding the function and dynamics of biological systems is not only knowledge of their structure, but the new methodologies and applications used to determine that structure. This volume in Biological Magnetic Resonance emphasizes the methods that involve Ultra High Field Magnetic Resonance Imaging. It will interest researchers working in the field of imaging.
Author: Niels Diffrient
Publisher:
ISBN: 9780999558812
Category :
Languages : en
Pages : 32
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Book Description
The Humanscale series is an important toolkit for everyone who designs for the human body. It incorporates the extensive amount of human engineering data compiled and organized by Henry Dreyfuss Associates throughout the twentieth century, including research of anthropologists, psychologists, scientists, human engineers, and medical experts.Originally published in 1974, Humanscale 1/2/3 consists of pictorial selectors equipped with rotary dials. This portfolio contains three selectors (two sides each) which present over 20,000 bits of information, encompassing anthropometry, guidelines for seating design, and requirements for the handicapped and elderly. Men, women, and children¿large and small¿¿are represented. Measurements are given in metric as well as English units.Engineers, architects, industrial designers, planners, interior and furniture designers, and craftsmen will find that the selectors minimize their searching through numerous and conflicting sources and unreliable information. The Humanscale materials are not a panacea, of course. More detailed studies dealing with interior space, safety, human strength and movement, displays, vision, reach, and controls should also be consulted. The selectors should be used in a creative way, and models and mock-ups based on the data should be tried out with the intended users.
Author: Jack T Tanabe
Publisher: World Scientific Publishing Company
ISBN: 9813101989
Category : Science
Languages : en
Pages : 355
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Book Description
This unique book, written by one of the world's foremost specialists in the field, is devoted to the design of low and medium field electromagnets whose field level and quality (uniformity) are dominated by the pole shape and saturation characteristics of the iron yoke.The wide scope covers material ranging from the physical requirements for typical high performance accelerators, through the mathematical relationships which describe the shape of two-dimensional magnetic fields, to the mechanical fabrication, assembly, installation, and alignment of magnets in a typical accelerator lattice. In addition, stored energy concepts are used to develop magnetic force relationships and expressions for magnets with time varying fields.The material in the book is derived from lecture notes used in a course at the Lawrence Livermore National Laboratory and subsequently expanded for the U.S. Particle Accelerator School, making this text an invaluable reference for students planning to enter the field of high energy physics.Mathematical relationships tying together magnet design and measurement theory are derived from first principles, and chapters are included that describe mechanical design, fabrication, installation, and alignment. Some fabrication and assembly practices are reviewed to ensure personnel and equipment safety and operational reliability of electromagnets and their power supply systems. This additional coverage makes the book an important resource for those already in the particle accelerator business as well as those requiring the design and fabrication of low and medium field level magnets for charged particle beam transport in ion implantation and medical applications.
Author: R. Belmans
Publisher: Springer Science & Business Media
ISBN: 1461519616
Category : Technology & Engineering
Languages : en
Pages : 380
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Book Description
This book contains the edited versions of the papers presented at the Second International Workshop on Electric and Magnetic Fields held at the Katholieke Universiteit van Leuven (Belgium) in May 1994. This Workshop deals with numerical solutions of electromagnetic problems in real life applications. The topics include coupled problems (thermal, mechanical, electric circuits), CAD & CAM applications, 3D eddy current and high frequency problems, optimisation and application oriented numerical problems. This workshop was organised jointly by the AIM (Association of Engineers graduated from de Montefiore Electrical Institute) together with the Departments of Electrical Engineering of the Katholieke Universiteit van Leuven (Prof. R. Belmans), the University of Gent (Prof. J. Melkebbek) and the University of Liege (Prof. W. Legros). These laboratories are working together in the framework of the Pole d'Attraction Interuniversitaire - Inter-University Attractie-Pole 51 - on electromagnetic systems led by the University of Liege and the research work they perform covers most of the topics of the Workshop. One of the principal aims of this Workshop was to provide a bridge between the electromagnetic device designers, mainly industrialists, and the electromagnetic field computation developers. Therefore, this book contains a continuous spectrum of papers from application of electromagnetic models in industrial design to presentation of new theoretical developments.
Author: Sergey Makarov
Publisher: Springer Nature
ISBN: 3030212939
Category : Technology & Engineering
Languages : en
Pages : 398
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Book Description
This open access book describes modern applications of computational human modeling with specific emphasis in the areas of neurology and neuroelectromagnetics, depression and cancer treatments, radio-frequency studies and wireless communications. Special consideration is also given to the use of human modeling to the computational assessment of relevant regulatory and safety requirements. Readers working on applications that may expose human subjects to electromagnetic radiation will benefit from this book’s coverage of the latest developments in computational modelling and human phantom development to assess a given technology’s safety and efficacy in a timely manner. Describes construction and application of computational human models including anatomically detailed and subject specific models; Explains new practices in computational human modeling for neuroelectromagnetics, electromagnetic safety, and exposure evaluations; Includes a survey of modern applications for which computational human models are critical; Describes cellular-level interactions between the human body and electromagnetic fields.
Author: Zhi-Pei Liang
Publisher: Wiley-IEEE Press
ISBN:
Category : Medical
Languages : en
Pages : 442
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Book Description
In 1971 Dr. Paul C. Lauterbur pioneered spatial information encoding principles that made image formation possible by using magnetic resonance signals. Now Lauterbur, "father of the MRI", and Dr. Zhi-Pei Liang have co-authored the first engineering textbook on magnetic resonance imaging. This long-awaited, definitive text will help undergraduate and graduate students of biomedical engineering, biomedical imaging scientists, radiologists, and electrical engineers gain an in-depth understanding of MRI principles. The authors use a signal processing approach to describe the fundamentals of magnetic resonance imaging. You will find a clear and rigorous discussion of these carefully selected essential topics: Mathematical fundamentals Signal generation and detection principles Signal characteristics Signal localization principles Image reconstruction techniques Image contrast mechanisms Image resolution, noise, and artifacts Fast-scan imaging Constrained reconstruction Complete with a comprehensive set of examples and homework problems, Principles of Magnetic Resonance Imaging is the must-read book to improve your knowledge of this revolutionary technique.
Author: Iosif B. Khriplovich
Publisher: Springer Science & Business Media
ISBN: 3642608388
Category : Science
Languages : en
Pages : 241
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Book Description
Electric dipole moments (EDMs) have interested physicists since 1950, when it was first suggested that there was no experimental evidence that nuclear forces are symmetric under parity (P) transformation. This question was regarded as speculative because the existence of an EDM, in addition to P violation, requires a violation of time-reversal (T) symmetry. In 1964 it was discovered that the invariance under CP transformation, which combines charge conjugation (C) with parity, is violated in K-meson decays. This provided a new incentive for EDM searches. Since the combined operations of CPT are expected to leave a system invariant, breakdown of CP invariance should be accompanied by a violation of time-reversal symmetry. Thus there is a reason to expect that EDMs should exist at some level. The original neutron EDM experiments were later supplemented with checks of T invariance in atoms and molecules. These investigations are pursued now by many groups. Over the years, the upper limit on the neutron EDM has been improved by seven orders of magnitude, and the upper limit on the electron EDM obtained in atomic experiments is even more strict.
