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- Magnetic Actuators and Sensors Second Edition By John R. Brauer
- Magnetic Actuators and Sensors
- Sensors and Actuators A: Physical
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Once production of your article has started, you can track the status of your article via Track Your Accepted Article. Help expand a public dataset of research that support the SDGs. Sensors and Actuators A: Physical brings together multidisciplinary interests in one journal entirely devoted to disseminating information on all aspects of research and development of solid-state devices for transducing physical signals. Sensors and Actuators A: Physical regularly publishes original
Magnetic Actuators and Sensors Second Edition By John R. Brauer
Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. History has shown that advancements in materials science and engineering have been important drivers in the development of sensor technologies. For instance, the temperature sensitivity of electrical resistance in a variety of materials was noted in the early s and was applied by Wilhelm von Siemens in to develop a temperature sensor based on a copper resistor.
The high resonance stability of single-crystal quartz, as well as its piezoelectric properties, have made possible an extraordinarily wide range of high performance, affordable sensors that have played an important role in everyday life and national defense. More recently, a new era in sensor technology was ushered in by the development of large-scale silicon processing, permitting the exploitation of silicon to create new methods for transducing physical phenomena into electrical output that can be readily processed by a computer.
Ongoing developments in materials technology will permit better control of material properties and behavior, thereby offering possibilities for new sensors with advanced features, such as greater fidelity, lower cost, and increased reliability.
To provide a foundation for its recommendations in these areas, the committee began by assessing the current status of sensor technologies. Early in this assessment, the committee found that applications, not materials, drive new sensor development. Therefore the committee identified a conceptual framework that could relate sensor materials to application needs within which the importance of particular sensor materials could be determined.
Given the extensive body of published work relating to the broad, multidisciplinary subject of sensor technologies, the committee prepared a summary bibliography drawn from the recent literature Appendix A. The bibliography includes review articles, books, and monographs relating to the wide range of sensor technologies. These references can form a basis from which a more detailed study of any particular sensing technology, principle, or application can be initiated.
Several key journals dealing with sensing have been included in the bibliography; they are suggested as starting points for investigating the most recent developments and trends in sensor technologies. Additional information is available from the reference list at the end of each chapter.
Despite the extensive published literature that treat the fundamentals of sensor technology, considerable ambiguity exists in sensor definition and classification, as illustrated by a recent buyer's. The latter list includes both physical phenomena for example, acoustic, electrochemical, Hall effect and infrared sensors , and material types such as bimetallic, fiberoptic, thick-and thin-film, and zirconium oxide sensors.
Understanding the physical or chemical effects that yield useful transduction is important in selecting and designing sensors. However, these effects by themselves are usually not sufficient to establish an unambiguous sensor classification, since typical sensors may use more than one effect.
A simple example is a diaphragm pressure gauge. The diaphragm uses one form of mechanical energy to create another pressure generates displacement and strain ; however, the creation of an electrical signal from the displacement or strain can be accomplished using many approaches.
The diaphragm could be made of a piezoelectric material, in which the air would induce an electrical charge; an inductive or capacitive effect could be employed to measure the charge related to the strain and the deflection and thereby infer the pressure. Thus understanding all of the possible field effects and features of transducer materials behavior provides the most complete set of sensor design options. In order to accelerate the incorporation of emerging sensor materials in new applications, it is critically important that the sensor materials community be able to readily identify sensing needs that candidate materials could fulfill.
The formal study of sensor technology is plagued by ambiguity in definitions and terminology. This evolving field of endeavor is extraordinarily broad with nearly every scientific and technical discipline playing an important role. Thus, it should not be surprising that there is no unanimous concept of a sensor. Given the impossibility of presenting a universally accepted definition for sensors, the committee used terms and definitions that are generally accepted in the current technical literature to provide the basis for discussion in this report.
The terms "sensor" and "transducer" have often been used as synonyms. An output is defined as an "electrical quantity," and a measurand is ''a physical quantity, property, or condition which is measured.
Therefore, the term "sensor" will be used throughout this report. The committee recognizes that, for the purpose of this report, the output of a sensor may be any form of energy. Many early sensors converted by transduction a physical measurand to mechanical energy; for example, pneumatic energy was used for fluid controls and mechanical energy for kinematic control. This need for electrical interfacing is causing a broadening in the definition of a sensor to include the systems interface and signal conditioning features that form an integral part of the sensing system.
With progress in optical computing and information processing, a new class of sensors, which involve the transduction of energy into an optical form, is likely. Also, sensors based on microelectromechanical systems may enable fluidic elements to operate as controls and actuation devices in the future.
Thus the definition of a "sensor" will continue to evolve. The definition of a sensor does not precisely define what physical elements constitute the sensor.
For example, what portion of a thermocouple is the sensor? Is it solely the bimetallic junction? Does it include the wires used for transmission purposes? Does it include any packaging or signal processing?
On the basis of information in the. Sensor element : The fundamental transduction mechanism e. Some sensors may incorporate more than one sensor element e. Sensor : A sensor element including its physical packaging and external connections e. Sensor system : A sensor and its assorted signal processing hardware analog or digital with the processing either in or on the same package or discrete from the sensor itself. In order to describe and characterize the performance of a sensor, a large and specific vocabulary is required.
Several excellent references, which provide a basic review of transducer characteristics,. Table lists some of the characteristics important for describing a sensor and its static and dynamic performance. Most of the characteristics listed under "static" are also important for dynamic measurements. Sensor characteristics will be discussed in greater detail in Chapter 2 in the context of a set of "descriptors" used by the committee to provide a common framework for sensor technologists and users.
Appendix B contains a definition for each of the sensor descriptors used in this report. Lion introduced a classification of principles according to the form of energy in which sensor signals were received and generated, which yielded a matrix of effects. Table lists the six energy forms or signal domains generally encountered with examples of typical properties that are measured using those energy forms.
The table demonstrates some interesting complexities in definitions. For example, a device that converts electrical energy into mechanical energy, such as by piezoelectricity which may be considered a sensor by definition , is more generally termed an output transducer or an actuator rather than a sensor.
Clearly then, the appropriate use of "sensor" or "actuator" is not based on physics but instead on the intent of the application. It is one method of visualizing the transduction principles involved in sensing. A rigorous attempt at classifying sensors was undertaken by Middlehoek and Noorlag , in which they represented the input and output energy.
Voltage, current, charge, resistance, inductance, capacitance, dielectric constant, polarization, electric field, frequency, dipole moment. Intensity, phase, wavelength, polarization, reflectance, transmittance, refractive index. Fluid Mechanical effects; e. Acoustic effects; e. Friction effects; e. Cooling effects; e. Photoelastic systems stress-induced birefringence. Sagnac effect. Doppler effect. Thermal expansion; e. Resonant frequency. Radiometer effect; e. Electrokinetic and electro-mechanical effects; e.
Electro-optical effects; e. Thermo-magnetic effects; e. Galvano-magnetic effects; e. Flame ionization. Volta effect. Gas sensitive field effect. Emission and absorption Spectroscopy. Photo-chemical effects. In addition, they included two other types of sensors: self-generating and modulating. They referred to self-generating and modulating as fundamental transduction principles to be included in a chart such as Table , thereby creating a third dimension.
A sensor based on a modulating principle requires an auxiliary energy source; one based on a self-generating principle does not. No standard convention has been established in the technical literature as to whether a modulating sensor should be classified as "passive" or "active"; both terms are used in the literature. Therefore, the committee adopted the terms "self-generating" and "modulating'' to avoid any confusion that could arise from the use of "passive" and "active.
They were drawn from previous National Materials Advisory Board reports on materials processing. The examples in the appendix include thermocouple, transducers, scale of measured properties, and typical constraints. A comparison of Figures and illustrates schematically the difference between a self-generating sensor and a modulating sensor. An example of a self-generating sensor is a piezoelectric pressure sensor. In this case, the mechanical energy form strain or pressure creates electrical signal an electrical charge as a result of the fundamental material behavior of the sensor element.
An example. The resulting change in the gauge length of the fiber is measured using interferometry i. Schematic representations of a piezoelectric pressure sensor and a fiberoptic magnetic-field sensor are depicted in Figures and , respectively. Often sensors incorporate more than one transduction principle; thus, sensors can be conveniently classified simply by their input energy form or signal domain of interest. The committee adopted a sensor taxonomy for this report that is based on the input energy form or measurand as a practical engineering-oriented approach that provides insight into selecting sensors technologies for applications.
This approach, however, does not emphasize the underlying mechanisms to the extent that a more science-based taxonomy would; this limitation is particularly telling when multiple response interactions occur. Nor does this approach lead to rapid identification of low-cost sensors, sensors that exploit a particular type of material, etc. Therefore, alternative sensor taxonomies are also useful.
Magnetic Actuators and Sensors
A MEMS magnetic actuator is a device that uses the microelectromechanical systems MEMS to convert an electric current into a mechanical output by employing the well-known Lorentz Force Equation or the theory of Magnetism. Micro-Electro-Mechanical System MEMS technology  is a process technology in which mechanical and electro-mechanical devices or structures are constructed using special micro-fabrication techniques. These techniques include: bulk micro-machining, surface micro-machining, LIGA , wafer bonding , etc. For the analysis of every MEMS device, the Lumped assumption is made: that if the size of the device is far less than the characteristic length scale of the phenomenon wave or diffusion , then there would be no spatial variations across the entire device. Modelling becomes easy under this assumption. These three operations require some form of transduction schemes, the most popular ones being: piezoelectric , electrostatic , piezoresistive , electrodynamic, magnetic and magnetostrictive. The MEMS magnetic actuators use the last three schemes for their operation.
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Sensors and Actuators A: Physical
Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. History has shown that advancements in materials science and engineering have been important drivers in the development of sensor technologies.
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Вы не поставили в известность Лиланда Фонтейна. Терпение Стратмора иссякло. Он взорвался: - Сьюзан, выслушай .
Он ждал, когда зазвонит прямой телефон, но звонка все не. Кто-то постучал в дверь.
An international journal devoted to research and development of physical transducers
Такая форма их размещения должна была способствовать интеллектуальному общению криптографов, напоминая им, что они всего лишь члены многочисленной команды - своего рода рыцари Круглого стола взломщиков кодов. По иронии судьбы в Третьем узле секреты не очень-то любили. Нареченный Детским манежем, Третий узел ничем не напоминал стерильную атмосферу остальной части шифровалки. Его обстановка напоминала домашнюю - мягкий ковер, высокотехнологичная звуковая система, холодильник, полный напитков и всяческой еды, маленькая кухня и даже баскетбольное кольцо. В отношении шифровалки в АНБ сложилась своеобразная философия.
В руке красная туристская сумка фирмы Л. Белл. Светлые волосы тщательно уложены. - Прошу меня извинить, - пробормотал Беккер, застегивая пряжку на ремне. - Мужская комната оказалась закрыта… но я уже ухожу. - Ну и проваливай, пидор.
Стратмор сурово посмотрел на. - Этот алгоритм создал один самых блестящих умов в криптографии. Сьюзан пришла в еще большее смятение: самые блестящие умы в криптографии работают в ее отделе, и уж она-то наверняка хоть что-нибудь услышала бы об этом алгоритме.
Неужели ему предстояло погибнуть по той же причине.