Harold Weinstock – författare

This work provides a review of recent advances in all aspects of superconducting electronics, both for the traditional (4 K) liquid helium based (LTS) materials and the more recent ceramic (HTS) materials that can operate at higher temperatures in the range of liquid nitrogen (77 K). Special emphasis has been placed on the rapid progress over the past two years in the fabrication of thin-film structures which provide the potential for vastly improved passive elements in microwave circuitry and active components for signal processing and magnetic sensors. The fundamentals of superconducting and single-electron tunneling, as well as a detailed explanation of SQUID fundamentals, are presented. Current and projected applications of superconducting electronic and magnetic-sensing elements are discussed. The book concludes with four chapters devoted to new generations of analog-to-digital converters and digital signal processors.This information should prove valuable to scientists and engineers engaged in R&D on improved electromagnetic sensing and signal processing, the fabrication of thin-film components, and practical applications of rapidly emerging LTS and HTS superconducting technology.

This text examines all aspects of constructing and using SQUID magnetic sensors that operate at either liquid helium or liquid nitrogen temperatures (4 or 77 K, respectively). There is comprehensive coverage of a range of established and emerging applications: biomagnetism, geophysics, nondestructive evaluation, detection of unexploded ordnance, and gravity gradiometry. The principles of both dc and rf SQUIDS are discussed extensively, as are the geometries, electronic circuitry and analysis techniques required to maximize performance. A major chapter of SQUID gradiometers in real environments presents original information on how to minimize noise from external sources. The discussions of biomagnetism describe the growing importance of neuromagnetometry with systems employing over 100 SQUID sensors, as well as the emergence of magnetocardiography and foetal heartbeat monitoring. Analysis techniques relevant to both biomagnetism and nondestructive evaluation are presented in depth.

This book should be of value to all those who are considering the use of or have only just begun to use the computer as a learning aid, regardless of the educational level and the discipline being considered. Although the focus is on computer-based instruction in physics and mathematics at the university- and secondary-school levels, the strategies and problems are universally applicable. At the NATO Advanced Study Institute upon which this volume is based, the obstacles encountered by those engaged in such activities were similar in each of the eighteen countries represented. Despite many false starts by those engaged in applying the computer as a learning aid, we believe unequivocally that the computer presents a unique educational tool yet to be exploited adequately. The reasons for slow development may become obvious as one reads this book: the effort required to achieve measurable success is not trivial. Extensive planning and team efforts are often necessary. Unfortunately, many well-intentioned educators discover this too late. We emphasize very early that it is the opportunity to engage students as active participants in the learning process which sets computer-based learning apart from the learning potential of other electronic media.

This book should be of value to all those who are considering the use of or have only just begun to use the computer as a learning aid, regardless of the educational level and the discipline being considered. Although the focus is on computer-based instruction in physics and mathematics at the university- and secondary-school levels, the strategies and problems are universally applicable. At the NATO Advanced Study Institute upon which this volume is based, the obstacles encountered by those engaged in such activities were similar in each of the eighteen countries represented. Despite many false starts by those engaged in applying the computer as a learning aid, we believe unequivocally that the computer presents a unique educational tool yet to be exploited adequately. The reasons for slow development may become obvious as one reads this book: the effort required to achieve measurable success is not trivial. Extensive planning and team efforts are often necessary. Unfortunately, many well-intentioned educators discover this too late. We emphasize very early that it is the opportunity to engage students as active participants in the learning process which sets computer-based learning apart from the learning potential of other electronic media.

The genesis of the NATO Advanced Study Institute (ASI) upon which this volume is based, occurred during the summer of 1986 when we came to the realization that there had been significant progress during the early 1980''s in the field of superconducting electronics and in applications of this technology. Despite this progress, there was a perception among many engineers and scientists that, with the possible exception of a limited number of esoteric fundamental studies and applications (e.g., the Josephson voltage standard or the SQUID magnetometer), there was no significant future for electronic systems incorporating superconducting elements. One of the major reasons for this perception was the aversion to handling liquid helium or including a closed-cycle helium liquefier. In addition, many critics felt that IBM''s cancellation of its superconducting computer project in 1983 was "proof" that superconductors could not possibly compete with semiconductors in high-speed signal processing. From our perspective, the need for liquid helium was outweighed by improved performance, i. e., higher speed, lower noise, greater sensitivity and much lower power dissipation. For many commercial, medical, scientific and military applications, these attributes can lead to either enhanced capability (e.g., compact real-time signal processing) or measurements that cannot be made using any other technology (e.g., SQUID magnetometry to detect neuromagnetic activity).