CALCULATION OF FREQUENCIES AND RELATIVE INTENSITIES OF NUCLEAR SPIN RESONANCE LINES IN CRYSTALS

1958 ◽  
Vol 36 (10) ◽  
pp. 1286-1294 ◽  
Author(s):  
M. Bloom ◽  
L. B. Robinson ◽  
G. M. Volkoff
Keyword(s):  
Magnetic Field ◽  
Nuclear Spin ◽  
Energy Levels ◽  
Magnetization Vector ◽  
Single Coil ◽  
Wide Range ◽  
Spin Resonance ◽  
Oscillating Magnetic Field ◽  
The Difference ◽  
Set Up

Previous calculations of the dependence on the strength of the external magnetic field H0 of the energy levels and the expected frequencies of nuclear spin resonance lines of Al27 nuclei in a single crystal of LiAl(SiO3)2 (spodumene) have been extended over a wide range of H0 to more general orientations of the crystal with respect to H0.In order to describe the variation with H0 of the relative signal strength of a nuclear spin resonance line in a crystal, as observed with a crossed-coil spectrometer, a system of modified Bloch equations has been set up which describe the behavior of the magnetization vector of a two-level system when transitions are induced by an oscillating magnetic field. Solutions of these equations are used to explain the difference in the dependence on H0 of signal strengths in crossed-coil and in single-coil spectrometers.

scholarly journals Dynamics of field-induced phases in spin-1 antifferomagnetic chains

2014 ◽  
Author(s):  
Χριστίνα Ψαρουδάκη
Keyword(s):  
Magnetic Field ◽  
Electron Spin Resonance ◽  
Theoretical Analysis ◽  
Electron Spin ◽  
Thermal Transport ◽  
Easy Plane ◽  
Xxz Model ◽  
Plane Anisotropy ◽  
Wide Range ◽  
Spin Resonance

This thesis is devoted to the study of a class of antifferomagnetic spin–1 chains with astrong easy plane anisotropy in the presence of magnetic field H. At zero temperature thesystem undergoes two quantum phase transitions at critical fields H1 and H2. Reliableand detailed theoretical analysis is provided on the Electron Spin Resonance (ESR)spectrum, thermodynamics and the thermal transport of the model. The tools at handrange from exact analytical solutions and to numerical simulation techniques. The S = 1antiferromagnet in a magnetic field can be systematically mapped onto an S = 1/2XXZ chain in a longitudinal magnetic field. This effective S = 1/2 description has beenextensively used in order to gain a better physical understanding of the original S = 1chain.For the Electron Spin Resonance spectrum, apart from the theoretical analysis, high-field ESR experimental studies of the compound N iCl2 − 4SC(NH2)2 (abbreviatedas DTN) are presented and found consistent with theoretical predictions. The mostinteresting feature is the experimental signature of the single–ion two–magnon boundstate.Part of this thesis is devoted to the magnetic–field and temperature dependence ofmagnetization and specific heat for the whole field–region and a wide range of temperatures,with special emphasis at the critical behaviour of these quantities at the criticalfields. Finally, the calculation of dynamic correlation functions pertinent to the studyof thermal transport is addressed for the S = 1 model with easy plane anisotropy andthe S = 1/2 XXZ model in the presence of finite magnetic field.

scholarly journals A review of the risk margin – Solvency II and beyond

2020 ◽  
Vol 25 ◽  
Author(s):  
A. J. Pelkiewicz ◽  
S. W. Ahmed ◽  
P. Fulcher ◽  
K. L. Johnson ◽  
S. M. Reynolds ◽  
...  
Keyword(s):  
Cost Of Capital ◽  
Working Party ◽  
Solvency Ii ◽  
Risk Margin ◽  
Life Insurers ◽  
Wide Range ◽  
The Difference ◽  
Set Up ◽  
The Uk ◽  
The Impact

Abstract For life insurers in the United Kingdom (UK), the risk margin is one of the most controversial aspects of the Solvency II regime which came into force in 2016. The risk margin is the difference between the technical provisions and the best estimate liabilities. The technical provisions are intended to be market-consistent, and so are defined as the amount required to be paid to transfer the business to another undertaking. In practice, the technical provisions cannot be directly calculated, and so the risk margin must be determined using a proxy method; the method chosen for Solvency II is known as the cost-of-capital method. Following the implementation of Solvency II, the risk margin came under considerable criticism for being too large and too sensitive to interest rate movements. These criticisms are particularly valid for annuity business in the UK – such business is of great significance to the system for retirement provision. A further criticism is that mitigation of the impact of the risk margin has led to an increase in reinsurance of longevity risks, particularly to overseas reinsurers. This criticism has led to political interest, and the risk margin was a major element of the Treasury Committee inquiry into EU Insurance Regulation. The working party was set up in response to this criticism. Our brief is to consider both the overall purpose of the risk margin for life insurers and solutions to the current problems, having regard to the possibility of post-Brexit flexibility. We have concluded that a risk margin in some form is necessary, although its size depends on the level of security desired, and so is primarily a political question. We have reviewed possible alternatives to the current risk margin, both within the existing cost-of-capital methodology and considering a wide range of alternatives. We believe that requirements for the risk margin will depend on future circumstances, in particular relating to Brexit, and we have identified a number of possible changes to methodology which should be considered, depending on circumstances.

scholarly journals The Electron Drift Instrument on Cluster: overview of first results

2001 ◽  
Vol 19 (10/12) ◽  
pp. 1273-1288 ◽  
Author(s):  
G. Paschmann ◽  
J. M. Quinn ◽  
R. B. Torbert ◽  
H. Vaith ◽  
C. E. McIlwain ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Fields ◽  
Drift Velocity ◽  
Electron Beams ◽  
Local Magnetic Field ◽  
Electron Drift ◽  
Plasma Convection ◽  
Wide Range ◽  
First Results ◽  
The Difference

Abstract. EDI measures the drift velocity of artificially injected electron beams. From this drift velocity, the perpendicular electric field and the local magnetic field gradients can be deduced when employing different electron energies. The technique requires the injection of two electron beams at right angles to the magnetic field and the search for those directions within the plane that return the beams to their associated detectors after one or more gyrations. The drift velocity is then derived from the directions of the two beams and/or from the difference in their times-of-flight, measured via amplitude-modulation and coding of the emitted electron beams and correlation with the signal from the returning electrons. After careful adjustment of the control parameters, the beam recognition algorithms, and the onboard magnetometer calibrations during the commissioning phase, EDI is providing excellent data over a wide range of conditions. In this paper, we present first results in a variety of regions ranging from the polar cap, across the magnetopause, and well into the magnetosheath.Key words. Electron drift velocity (electric fields; plasma convection; instruments and techniques)

scholarly journals High-Frequency Non-Invasive Magnetic Field-Based Condition Monitoring of SiC Power MOSFET Modules

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6720
Author(s):  
Javad Naghibi ◽  
Kamyar Mehran ◽  
Martin P. Foster
Keyword(s):  
Magnetic Field ◽  
Condition Monitoring ◽  
Switching Frequency ◽  
Power Module ◽  
Power Mosfet ◽  
Wire Bond ◽  
Wide Range ◽  
The Wire ◽  
Lift Off ◽  
Set Up

Current distribution anomaly can be used to indicate the onset of package-related failures modes in Silicon Carbide power MOSFET modules. In this paper, we propose to obtain the wire bond’s magnetic field profile using an array of Tunnel Magneto-Resistance (TMR) sensors, and characterise the small changes in the current density distribution to find the onset of the wire bond degradation processes, including wire bond lift-off, wire bond cracking, and wire bond fracture. We propose a novel condition monitoring technique where a non-galvanic high-bandwidth sensing and a reliability model monitor the health of the power switches. We designed a dedicated calibration set-up to examine the sensor array and calibrated to demonstrate the adequate sensitivity to a minimum 5% current anomaly detection in a single wire bond of the switching devices operating with 50 kHz switching frequency. We use a hardware-in-the-loop (HIL) experimental set-up to replicate wire bond-related failures in a 1200V/55A SiC MOSFET power module of a DC/DC Boost converter. Signal conditioning circuits are further designed to amplify and buffer the sensor readings. Experimental results showed the proposed technique is able to detect a wide range of package-related failures.

Specific Futures of Optical Anisotropy in Terbium Iron and Terbium Gallium Garnets

2014 ◽  
Vol 605 ◽  
pp. 553-556
Author(s):  
Natalia Tsidaeva ◽  
Viktorija Abaeva ◽  
Anatoly Turiev ◽  
Elena Enaldieva ◽  
Tengiz Butkhuzi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Energy Levels ◽  
Strong Dependence ◽  
Polarized Light ◽  
Magnetization Vector ◽  
Linear Dichroism ◽  
Linear Birefringence ◽  
Optical Channels ◽  
Linearly Polarized ◽  
Magnetic Linear Dichroism

We reported magnetooptical properties of Tb3+in single crystals of Tb3Fe5O12and Tb3Ga5O12for ion occupying sites of D2symmetry in the garnets structure. It is shown that in the employed Voigt geometry the magnetic linear birefringence and the dichroism reach values 10-4, and have a strong dependence on the wavelength and a strong anisotropy. The absorption spectra were obtained at temperatures of 30K, 100K using magnetic field up to 25 kOe applied parallel and perpendiculare to the electric vector E linearly polarized light on the7F67F0and7F67F1optical transitions region. The aim of this research was revealing of a role of contributions of exchange interaction and a crystal field in splitting of energy levels of the basic condition7F6ion Tb3+multiplet in Tb ferrite-garnet by studying of character of spectra magnetic linear dichroism (MLD) paramagnetic and ferrimagnetic crystals placed in an external magnetic field. More over, the assumption about nonreciprocity of magnetic linear birefringence (MLB) spectra and dichroism with the change of the relative orientation of the magnetization vector I and the light wave vector has been experimentally confirmed. This effect may use as a base for the design of the different transducers, for example, magnetooptical optical channels commutator.

Measurement of the Dynamic Modulus of Rubber at Very Small Amplitudes with an Optical Interferometer

1960 ◽  
Vol 33 (2) ◽  
pp. 272-274
Author(s):  
N. M. Borovitskaya
Keyword(s):  
Interference Pattern ◽  
Dynamic Modulus ◽  
Dynamic Properties ◽  
Monochromatic Light ◽  
Michelson Interferometer ◽  
Light Modulation ◽  
Wide Range ◽  
Narrow Band Filter ◽  
The Difference ◽  
Set Up

Abstract A method of measuring very small differences of optical path using light modulation by an interferometer has been described. This enables one to measure amplitudes of mechanical vibrations of the order of 0.01 A or even smaller. We have used this method to measure the dynamic modulus of rubber at very small amplitudes. It is desirable to use this method for measuring the dynamic modulus of rubber and other highly elastic substances, firstly because in accuracy and simplicity it has certain advantages over existing acoustic methods. In the second place, it enables one to work at very small amplitudes and, in association with other methods, over a very wide range of amplitudes of deformation. This is of interest in connection with the general theory of the dynamic properties of rubber, and in particular, for checking the linearity of these properties, that is, the independence of the modulus and the loss on the amplitude, in particular for filled rubbers. We will briefly describe the apparatus with which the measurements were made. It consists of a Michelson interferometer and a source of monochromatic light. The interference pattern (lines of equal width) is projected onto the cathode of a photomultiplier. The output of the photo multiplier is fed to the input of a narrow-band filter, to the output of which the measuring instrument is connected. The mirror on the interferometer is set up so that the whole of the interference pattern, or the greater part of it, is uniformly illuminated. If now one of the mirrors vibrates with a frequency ω and an amplitude of z, then the difference in path between the interference beams will vary with a frequency of ω and the intensity of the light falling on the photomultiplier will also change. The current through the photomultiplier will be modulated with a frequency of ω. The first harmonic of the photocurrent will be I1=AJ1(4τz/λ), where λ is the wavelength of light; A is a coefficient depending on the intensity of the interfering beams and on their difference of path with the mirror at rest; I1 is a first order Bessel function.

Comparative Effects of High-Tech Visual Scene Displays and Low-Tech Isolated Picture Symbols on Engagement From Students With Multiple Disabilities

2019 ◽  
Vol 50 (4) ◽  
pp. 693-702 ◽  
Author(s):  
Christine Holyfield ◽  
Sydney Brooks ◽  
Allison Schluterman
Keyword(s):  
Language Learning ◽  
Augmentative And Alternative Communication ◽  
Visual Analysis ◽  
Multiple Disabilities ◽  
Visual Scene ◽  
Future Research ◽  
High Tech ◽  
Single Subject ◽  
Wide Range ◽  
The Difference

Purpose Augmentative and alternative communication (AAC) is an intervention approach that can promote communication and language in children with multiple disabilities who are beginning communicators. While a wide range of AAC technologies are available, little is known about the comparative effects of specific technology options. Given that engagement can be low for beginning communicators with multiple disabilities, the current study provides initial information about the comparative effects of 2 AAC technology options—high-tech visual scene displays (VSDs) and low-tech isolated picture symbols—on engagement. Method Three elementary-age beginning communicators with multiple disabilities participated. The study used a single-subject, alternating treatment design with each technology serving as a condition. Participants interacted with their school speech-language pathologists using each of the 2 technologies across 5 sessions in a block randomized order. Results According to visual analysis and nonoverlap of all pairs calculations, all 3 participants demonstrated more engagement with the high-tech VSDs than the low-tech isolated picture symbols as measured by their seconds of gaze toward each technology option. Despite the difference in engagement observed, there was no clear difference across the 2 conditions in engagement toward the communication partner or use of the AAC. Conclusions Clinicians can consider measuring engagement when evaluating AAC technology options for children with multiple disabilities and should consider evaluating high-tech VSDs as 1 technology option for them. Future research must explore the extent to which differences in engagement to particular AAC technologies result in differences in communication and language learning over time as might be expected.

Settlers or Movers? The Temporality of Past Migrations, Political Inaction and its Consequences, 1945–1985

2018 ◽  
Author(s):  
Jozefien De Bock
Keyword(s):  
Temporary Workers ◽  
Guest Workers ◽  
Temporary Migration ◽  
Wide Range ◽  
Settler Societies ◽  
Future Policy ◽  
Set Up ◽  
Legal Frameworks ◽  
Temporary Migrants ◽  
Multicultural Policies

Historically, those societies that have the longest tradition in multicultural policies are settler societies. The question of how to deal with temporary migrants has only recently aroused their interest. In Europe, temporary migration programmes have a much longer history. In the period after WWII, a wide range of legal frameworks were set up to import temporary workers, who came to be known as guest workers. In the end, many of these ‘guests’ settled in Europe permanently. Their presence lay at the basis of European multicultural policies. However, when these policies were drafted, the former mobility of guest workers had been forgotten. This chapter will focus on this mobility of initially temporary workers, comparing the period of economic growth 1945-1974 with the years after the 1974 economic crisis. Further, it will look at the kind of policies that were developed towards guest workers in the era before multiculturalism. This way, it shows how their consideration as temporary residents had far-reaching consequences for the immigrants, their descendants and the receiving societies involved. The chapter will finish by suggesting a number of lessons from the past. If the mobility-gap between guest workers and present-day migrants is not as big as generally assumed, then the consequences of previous neglect should serve as a warning for future policy making.

COMBINATORIAL POLYNOMIALLY COMPUTABLE CHARACTERISTICS OF SUBSTITUTIONS AND THEIR PROPERTIES

2020 ◽  
Vol 7 (2) ◽  
pp. 34-41
Author(s):  
VLADIMIR NIKONOV ◽  
◽  
ANTON ZOBOV ◽  
Keyword(s):  
Mathematical Expectation ◽  
Point Of View ◽  
Small Range ◽  
Computational Point ◽  
Wide Range ◽  
Bijective Function ◽  
The Difference ◽  
Element Base ◽  
Selection Of

The construction and selection of a suitable bijective function, that is, substitution, is now becoming an important applied task, particularly for building block encryption systems. Many articles have suggested using different approaches to determining the quality of substitution, but most of them are highly computationally complex. The solution of this problem will significantly expand the range of methods for constructing and analyzing scheme in information protection systems. The purpose of research is to find easily measurable characteristics of substitutions, allowing to evaluate their quality, and also measures of the proximity of a particular substitutions to a random one, or its distance from it. For this purpose, several characteristics were proposed in this work: difference and polynomial, and their mathematical expectation was found, as well as variance for the difference characteristic. This allows us to make a conclusion about its quality by comparing the result of calculating the characteristic for a particular substitution with the calculated mathematical expectation. From a computational point of view, the thesises of the article are of exceptional interest due to the simplicity of the algorithm for quantifying the quality of bijective function substitutions. By its nature, the operation of calculating the difference characteristic carries out a simple summation of integer terms in a fixed and small range. Such an operation, both in the modern and in the prospective element base, is embedded in the logic of a wide range of functional elements, especially when implementing computational actions in the optical range, or on other carriers related to the field of nanotechnology.

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