Measuring magnetic fields

Magnetism often has a slight overtone of being mysterious. This is probably caused by the surprisingly strong forces between magnets which everybody can experience with magnetic toys, magnet boards, or similar objects. A strange effect is the unique ability of magnetic fields to penetrate many substances without any attenuation. Though the physical basis of magnetism is well explored, the outsider usually does not know very much about the details and sometimes tends to overestimate the real possibilities provided by magnetism.

656p chuyenphimbuon 21-07-2012 32 9   Download

Photon - axion conversions in static electromagnetic fields of the size a × b × c are considered in detail by the Feynman diagram methods. The differential cross sections are presented and the numerical evaluations of the total cross section are given. Our result shows that the conversion cross-sections in the electric field are quite small, while in the strong magnetic field, the cross-sections are much enhanced, which can be measurable in current experiments.

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The result of magnetization measurements showed that the magnetization at a magnetic field as high as 1 T abnormally depends on x, increases with increasing x to a maximum at x=0.1 then decreases monotonously afterward. There are possibilities to account for this anomalous magnetic behavior such as the Fe3+-to-Fe4+ and/or Ti4+-to-Ti3+ change(s) induced by oxygen vacancies. The substitution of Fe into Ti sites also changes the conductivity of the material and impurity (acceptor) levels in the band gap.

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The Potts model on a Cayley tree in the presence of competing two binary interactions and magnetic field is considered. We exactly solve a problem of phase transitions for the model, namely we calculate critical surface such that there is a phase transition above it and a single Gibbs state found elsewhere.

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The field of medical imaging is advancing at a rapid pace. Imaging modalities like x-ray radiography, x-ray computed tomography (CT), ultrasound, nuclear imaging, magnetic resonance imaging (MRI), and optical imaging have been used in biology and medicine to visualize anatomical structures as large as the lung and liver and as small as molecules. Ultrasound is considered the most cost-effective among them. It is used routinely in hospitals and clinics for diagnosing a variety of diseases.

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The West Pearl Queen reservoir project also used soil gas surveys to detect PFC tracers that were injected into the reservoir with the CO2. Soil gas sampling was conducted before and after the CO2 injection by using capillary tubes and adsorbent packets for the tracers. Brookhaven National Laboratory (BNL) supplied the tracers and performed the tracer concentration analysis (Wells et al., 2007). Near-Surface Geophysics – The use of magnetometers is another possible near-surface geophysical technique.

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Today, research and technology play a decisive role for the European food sector for the development of new products as well as for improved safety measures. In July 2000, DG RTD requested a study on potential future European research priorities in food technology and food safety from the Institute for Prospective Technological Studies (IPTS), Joint Research Centre. The study design comprised the involvement of external expertise from industry as well as from academia: The results of the study were derived from two experts workshops held in Sevilla at the IPTS in December 2000 and May 2001.

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The Gaussian spin fluctuation theory is applied to study magnetic properties (Curie temperature, magnetization) of EuO ultra-thin films within nearest neighbor and next nearest neighbor exchange approximation. The dependence of Curie temperature on the thickness of the free EuO ultrathin film is calculated and compared with the results of the other mean field methodconstant coupling approximation. The effect of nearly independence of saturation magnetization on the EuO films thickness measured in [8] can be explained by controlling the next nearest neighbor exchange in presence of substrates.

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In this work, a highly sensitive low-field magnetometer has been implemented for navigation, electronic compass, and monitoring security. The sensor structure consists of the soft-magnetic core cobalt base, the excitation coil, and the sensing coil. A current passing through the excitation coil at high frequency modulates the permeability of the soft magnetic core.

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Summary. In this introductory chapter, the definition and history of tribology and their industrial significance and origins and significance of an emerging field of micro/nanotribology are described. Next, various measurement techniques used in micro/nanotribological and micro/nanomechanical studies are described. The interest in micro/nanotribology field grew from magnetic storage devices and latter the applicability to emerging field micro/nanoelectromechanical systems (MEMS/NEMS) became clear.

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The first edition of the Handbook of Micro/Nanotribology was published in the Spring of 1995. Soon after its publication, the first-of-a-kind monograph became a reference book for the novice, as well as experts, in the emerging field of micro/nanotribology. Since the field is evolving very rapidly, we felt that the monograph needed a second edition. The second edition is totally revised. The scope of the first edition has been expanded. In the first part, Basic Studies, two new chapters on AFM Instrumentation and Tips and Surface Forces and Adhesion have been added.

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This article (see also [1, 2]) considers new methods for multiple electromagnetic source localization using sensors whose output is a vector corresponding to the complete electric andmagneticfields at the sensor. These sensors, which will be called vector sensors, can consist for example of two orthogonal triads of scalar sensors that measure the electric and magnetic field components. Our approach is in contrast to other articles in this chapter that employ sensor arrays in which the output of each sensor is a scalar corresponding, for example, to a scalar function of the electric field....

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A great deal has transpired since the final reprint of the previous edition of Fundamentals of Vacuum Technology appeared in 1987. LEYBOLD has in the meantime introduced a number of new developments in the field. These include the dry-running ALL×ex chemicals pump, the COOLVAC-FIRST cryopump systems with quick regeneration feature, turbomolecular pumps with magnetic bearings, the A-Series vacuum gauges, the TRANSPECTOR and XPR mass spectrometer transmitters, leak detectors in the UL series, and the ECOTEC 500 leak detector for refrigerants and many other gases.

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Güttinger et al. Nanoscale Research Letters 2011, 6:253 http://www.nanoscalereslett.com/content/6/1/253 NANO EXPRESS Open Access Transport through a strongly coupled graphene quantum dot in perpendicular magnetic field Johannes Güttinger1*, Christoph Stampfer1,2, Tobias Frey1, Thomas Ihn1 and Klaus Ensslin1 Abstract We present transport measurements on a strongly coupled graphene quantum dot in a perpendicular magnetic field.

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The first is Faraday’s law of induction, the second is Amp`ere’s law as amended by Maxwell to include the displacement current ∂D/∂t, the third and fourth are Gauss’ laws for the electric and magnetic fields. The displacement current term ∂D/∂t in Amp`ere’s law is essential in predicting the existence of propagating electromagnetic waves. Its role in establishing charge conservation is discussed in Sec. 1.7. Eqs. (1.1.1) are in SI units.

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n this book some recent advances in development of photodetectors and photodetection systems for specific applications are included. In the first section of the book nine different types of photodetectors and their characteristics are presented. Next, some theoretical aspects and simulations are discussed. The last eight chapters are devoted to the development of photodetection systems for imaging, particle size analysis, transfers of time, measurement of vibrations, magnetic field, polarization of light, and particle energy.

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Magnetotelluric surveys (soundings) are a naturalsource electromagnetic (EM) geophysical method that utilizes variations in the Earth’s magnetic field to image subsurface structures. A magnetotelluric sounding was attempted at Weyburn but has not produced results. Consequently, a final assessment of its utility is not available (Monea et al., 2008). Electrical resistance tomography (ERT) is a technique of imaging subsurface electrical conductivity. When deployed in time-lapse mode, it is capable of detecting conductivity changes caused by the injection of CO2.

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This paper presents the fabrication of CoNiP single segment and CoNiP/Au multisegment nanowires. We have fabricated these nanowires by electrodeposition method into polycarbonate templates with a nominal pore diameter about 100 nm. The hystersis loops were measured with the applied magnetic field parallel and perpendicular to the wire axis using a vibrating sample magnetometer (VSM).

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Velocity encoded phase-contrast magnetic resonance imaging (VE-PC MRI) is another imaging technique used to noninvasively measure Achilles tendon strain and changes in its force-displacement relationship concomitant with chronic unloading and subsequent recuperation. This technique will be reviewed in terms of its ability to quantify the Achilles tendon Young’s modulus (MPa) from a stress-strain curve.

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