Development of methodology for determining a-parameters of an asymmetric rail line

The article considers the methodology of forming the matrix of A-parameters of a rail line, represented by a multi-pole equivalent circuit. It is shown that when using a four-pole equivalent circuit of a rail line in case of violation of the equipotentiality of the circuit, it is impossible to take into account the flow of current along bypass paths, along the earth path, and the influence of adjacent track circuits. A multi-pole equivalent circuit of a rail line is represented as a 2x4 pole, in the rail lines of which self-induction EMF sources are included, and an earth path is used as the second wire. An equivalent multi-pole of equivalent circuit is represented by two groups of poles – at the input and output of the rail line, including one common (ground). The parameters of all elements of the equivalent multi-pole circuit are presented in the form of matrices, which makes it possible to analyze the state of the rail lines when changing the primary parameters of the rail multi-pole in a wide range. Using Kirchhoff's laws and solving a system of ordinary differential equations, the A-parameters of a rail multi-pole are obtained.

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Computers in Geology - 25 Years of Progress

10.1093/oso/9780195085938.001.0001 ◽

1994 ◽

Keyword(s):

Computer Modeling ◽

Quantitative Methods ◽

State Of The Art ◽

International Association ◽

Mathematical Geology ◽

25Th Anniversary ◽

The Earth ◽

Wide Range ◽

History Of ◽

Mapping Techniques

This volume vividly demonstrates the importance and increasing breadth of quantitative methods in the earth sciences. With contributions from an international cast of leading practitioners, chapters cover a wide range of state-of-the-art methods and applications, including computer modeling and mapping techniques. Many chapters also contain reviews and extensive bibliographies which serve to make this an invaluable introduction to the entire field. In addition to its detailed presentations, the book includes chapters on the history of geomathematics and on R.G.V. Eigen, the "father" of mathematical geology. Written to commemorate the 25th anniversary of the International Association for Mathematical Geology, the book will be sought after by both practitioners and researchers in all branches of geology.

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Much Ado about (Practically) Nothing

10.1093/oso/9780195393965.001.0001 ◽

2010 ◽

Author(s):

David Fisher

Keyword(s):

Energy Source ◽

Atomic Nucleus ◽

The Sun ◽

Scientific Journals ◽

Rare Gases ◽

Important Work ◽

The Earth ◽

Wide Range ◽

Life On Mars ◽

The Universe

There are eight columns in the Periodic Table. The eighth column is comprised of the rare gases, so-called because they are the rarest elements on earth. They are also called the inert or noble gases because, like nobility, they do no work. They are colorless, odorless, invisible gases which do not react with anything, and were thought to be unimportant until the early 1960s. Starting in that era, David Fisher has spent roughly fifty years doing research on these gases, publishing nearly a hundred papers in the scientific journals, applying them to problems in geophysics and cosmochemistry, and learning how other scientists have utilized them to change our ideas about the universe, the sun, and our own planet. Much Ado about (Practically) Nothing will cover this spectrum of ideas, interspersed with the author's own work which will serve to introduce each gas and the important work others have done with them. The rare gases have participated in a wide range of scientific advances-even revolutions-but no book has ever recorded the entire story. Fisher will range from the intricacies of the atomic nucleus and the tiniest of elementary particles, the neutrino, to the energy source of the stars; from the age of the earth to its future energies; from life on Mars to cancer here on earth. A whole panoply that has never before been told as an entity.

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Influence of Alumina Nanofibers Sintered by the Spark Plasma Method on Nickel Mechanical Properties

Metals ◽

10.3390/met11040548 ◽

2021 ◽

Vol 11 (4) ◽

pp. 548 ◽

Cited By ~ 1

Author(s):

Leonid Agureev ◽

Valeriy Kostikov ◽

Zhanna Eremeeva ◽

Svetlana Savushkina ◽

Boris Ivanov ◽

...

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Elastic Modulus ◽

Strength Properties ◽

Alumina Nanoparticles ◽

Metal Powders ◽

Wide Range ◽

The Matrix ◽

Spark Plasma ◽

Average Size

The article presents the study of alumina nanoparticles’ (nanofibers) concentration effect on the strength properties of pure nickel. The samples were obtained by spark plasma sintering of previously mechanically activated metal powders. The dependence of the grain size and the relative density of compacts on the number of nanofibers was investigated. It was found that with an increase in the concentration of nanofibers, the average size of the matrix particles decreased. The effects of the nanoparticle concentration (0.01–0.1 wt.%) on the elastic modulus and tensile strength were determined for materials at 25 °C, 400 °C, and 750 °C. It was shown that with an increase in the concentration of nanofibers, a 10–40% increase in the elastic modulus and ultimate tensile strength occurred. A comparison of the mechanical properties of nickel in a wide range of temperatures, obtained in this work with materials made by various technologies, is carried out. A description of nanofibers’ mechanisms of influence on the structure and mechanical properties of nickel is given. The possible impact of impurity phases on the properties of nickel is estimated. The tendency of changes in the mechanical properties of nickel, depending on the concentration of nanofibers, is shown.

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Estimating the number of usability problems affecting medical devices: modelling the discovery matrix

BMC Medical Research Methodology ◽

10.1186/s12874-020-01091-y ◽

2020 ◽

Vol 20 (1) ◽

Author(s):

Vincent Vandewalle ◽

Alexandre Caron ◽

Coralie Delettrez ◽

Renaud Périchon ◽

Sylvia Pelayo ◽

...

Keyword(s):

Medical Devices ◽

Market Access ◽

Real Life ◽

Usability Testing ◽

Probability Of Detection ◽

Usability Problems ◽

Usability Problem ◽

Wide Range ◽

The Matrix ◽

Problem Detection

Abstract Background Usability testing of medical devices are mandatory for market access. The testings’ goal is to identify usability problems that could cause harm to the user or limit the device’s effectiveness. In practice, human factor engineers study participants under actual conditions of use and list the problems encountered. This results in a binary discovery matrix in which each row corresponds to a participant, and each column corresponds to a usability problem. One of the main challenges in usability testing is estimating the total number of problems, in order to assess the completeness of the discovery process. Today’s margin-based methods fit the column sums to a binomial model of problem detection. However, the discovery matrix actually observed is truncated because of undiscovered problems, which corresponds to fitting the marginal sums without the zeros. Margin-based methods fail to overcome the bias related to truncation of the matrix. The objective of the present study was to develop and test a matrix-based method for estimating the total number of usability problems. Methods The matrix-based model was based on the full discovery matrix (including unobserved columns) and not solely on a summary of the data (e.g. the margins). This model also circumvents a drawback of margin-based methods by simultaneously estimating the model’s parameters and the total number of problems. Furthermore, the matrix-based method takes account of a heterogeneous probability of detection, which reflects a real-life setting. As suggested in the usability literature, we assumed that the probability of detection had a logit-normal distribution. Results We assessed the matrix-based method’s performance in a range of settings reflecting real-life usability testing and with heterogeneous probabilities of problem detection. In our simulations, the matrix-based method improved the estimation of the number of problems (in terms of bias, consistency, and coverage probability) in a wide range of settings. We also applied our method to five real datasets from usability testing. Conclusions Estimation models (and particularly matrix-based models) are of value in estimating and monitoring the detection process during usability testing. Matrix-based models have a solid mathematical grounding and, with a view to facilitating the decision-making process for both regulators and device manufacturers, should be incorporated into current standards.

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A Robust Weak Taylor Approximation Scheme for Solutions of Jump-Diffusion Stochastic Delay Differential Equations

Abstract and Applied Analysis ◽

10.1155/2013/750147 ◽

2013 ◽

Vol 2013 ◽

pp. 1-8

Author(s):

Yanli Zhou ◽

Yonghong Wu ◽

Xiangyu Ge ◽

B. Wiwatanapataphee

Keyword(s):

Differential Equations ◽

Delay Differential Equations ◽

Approximation Scheme ◽

Jump Diffusion ◽

Mathematical Finance ◽

Stochastic Delay Differential Equations ◽

Stochastic Delay ◽

Taylor Approximation ◽

Wide Range ◽

Delay Differential

Stochastic delay differential equations with jumps have a wide range of applications, particularly, in mathematical finance. Solution of the underlying initial value problems is important for the understanding and control of many phenomena and systems in the real world. In this paper, we construct a robust Taylor approximation scheme and then examine the convergence of the method in a weak sense. A convergence theorem for the scheme is established and proved. Our analysis and numerical examples show that the proposed scheme of high order is effective and efficient for Monte Carlo simulations for jump-diffusion stochastic delay differential equations.

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Human Rights as Land Rights in the Pacific

Pacifica Australasian Theological Studies ◽

10.1177/1030570x9300600104 ◽

1993 ◽

Vol 6 (1) ◽

pp. 61-80 ◽

Cited By ~ 1

Author(s):

John D'Arcy May

Keyword(s):

Human Rights ◽

Case Studies ◽

Papua New Guinea ◽

Land Rights ◽

Human Community ◽

The Earth ◽

The Pacific ◽

West Papua ◽

The Matrix ◽

The One

Do human rights in their conventional, Western understanding really meet the needs of Pacific peoples? This article argues that land rights are a better clue to those needs. In Aboriginal Australia, Fiji, West Papua and Papua New Guinea, case studies show that people's relationship to land is religious and implicitly theological. The article therefore suggests that rights to land need to be supplemented by rights of the land extending to the earth as the home of the one human community and nature as the matrix of all life.

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In-Situ Cosmogenic 14C: Production and Examples of its Unique Applications in Studies of Terrestrial and Extraterrestrial Processes

Radiocarbon ◽

10.1017/s0033822200041394 ◽

2001 ◽

Vol 43 (2B) ◽

pp. 731-742 ◽

Cited By ~ 8

Author(s):

D Lal ◽

A J T Jull

Keyword(s):

Half Life ◽

Earth Science ◽

Chemical Properties ◽

Radioactive Isotopes ◽

Earth’S Atmosphere ◽

The Earth ◽

Wide Range ◽

History Of ◽

Earth's Atmosphere

Nuclear interactions of cosmic rays produce a number of stable and radioactive isotopes on the earth (Lai and Peters 1967). Two of these, 14C and 10Be, find applications as tracers in a wide variety of earth science problems by virtue of their special combination of attributes: 1) their source functions, 2) their half-lives, and 3) their chemical properties. The radioisotope, 14C (half-life = 5730 yr) produced in the earth's atmosphere was the first to be discovered (Anderson et al. 1947; Libby 1952). The next longer-lived isotope, also produced in the earth's atmosphere, 10Be (half-life = 1.5 myr) was discovered independently by two groups within a decade (Arnold 1956; Goel et al. 1957; Lal 1991a). Both the isotopes are produced efficiently in the earth's atmosphere, and also in solids on the earth's surface. Independently and jointly they serve as useful tracers for characterizing the evolutionary history of a wide range of materials and artifacts. Here, we specifically focus on the production of 14C in terrestrial solids, designated as in-situ-produced 14C (to differentiate it from atmospheric 14C, initially produced in the atmosphere). We also illustrate the application to several earth science problems. This is a relatively new area of investigations, using 14C as a tracer, which was made possible by the development of accelerator mass spectrometry (AMS). The availability of the in-situ 14C variety has enormously enhanced the overall scope of 14C as a tracer (singly or together with in-situ-produced 10Be), which eminently qualifies it as a unique tracer for studying earth sciences.

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Ni Content Surface Layer Produced by Laser Surface Treatment on Amorphisable Cu Base Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.649.101 ◽

2010 ◽

Vol 649 ◽

pp. 101-106

Author(s):

Mária Svéda ◽

Dóra Janovszky ◽

Kinga Tomolya ◽

Jenő Sólyom ◽

Zoltán Kálazi ◽

...

Keyword(s):

Surface Layer ◽

Surface Treatment ◽

Laser Cladding ◽

Base Alloy ◽

Laser Surface ◽

Laser Alloying ◽

Laser Surface Treatment ◽

Ni Content ◽

Wide Range ◽

The Matrix

The aim of our research was to comparatively examine Ni content surface layers on amorphisable Cu base alloy produced by different laser surface treatments. Laser surface treatment (LST) techniques, such as laser surface melting, laser alloying and laser cladding, provide a wide range of interesting solutions for the production of wear and corrosion resistant surfaces. [1,2] With LST techniques, the surface can be: i) coated with a layer of another material by laser cladding, ii) the composition of the matrix can be modified by laser alloying. [3] Two kinds of laser surface treatment technologies were used. In the case of coating-melting technology a Ni content surface layer was first developed by galvanization, and then the Ni content layer was melted together with the matrix. In the case of powder blowing technology Ni3Al powder was blown into the layer melted by laser beam and Argon gas. LST was performed using an impulse mode Nd:YAG laser. The laser power and the interaction time were 2 kW and 20÷60 ms. The characterization of the surface layer microstructure was performed by XRD, scanning electron microscopy and microhardness measurements.

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Optimising the AR Engraved Structure on Light-Guide Facets for a Wide Range of Wavelengths

Optics ◽

10.3390/opt2010002 ◽

2020 ◽

Vol 2 (1) ◽

pp. 25-42

Author(s):

Ioseph Gurwich ◽

Yakov Greenberg ◽

Kobi Harush ◽

Yarden Tzabari

Keyword(s):

Theoretical Analysis ◽

Light Guide ◽

Spectral Band ◽

Angular Range ◽

The Past ◽

Input And Output ◽

Wide Range ◽

The Given ◽

Theoretical Results ◽

Shape And Size

The present study is aimed at designing anti-reflective (AR) engraving on the input–output surfaces of a rectangular light-guide. We estimate AR efficiency, by the transmittance level in the angular range, determined by the light-guide. Using nano-engraving, we achieve a uniform high transmission over a wide range of wavelengths. In the past, we used smoothed conical pins or indentations on the faces of light-guide crystal as the engraved structure. Here, we widen the class of pins under consideration, following the physical model developed in the previous paper. We analyze the smoothed pyramidal pins with different base shapes. The possible effect of randomization of the pins parameters is also examined. The results obtained demonstrate optimized engraved structure with parameters depending on the required spectral range and facet format. The predicted level of transmittance is close to 99%, and its flatness (estimated by the standard deviation) in the required wavelengths range is 0.2%. The theoretical analysis and numerical calculations indicate that the obtained results demonstrate the best transmission (reflection) we can expect for a facet with the given shape and size for the required spectral band. The approach is equally useful for any other form and of the facet. We also discuss a simple way of comparing experimental and theoretical results for a light-guide with the designed input and output features. In this study, as well as in our previous work, we restrict ourselves to rectangular facets. We also consider the limitations on maximal transmission produced by the size and shape of the light-guide facets. The theoretical analysis is performed for an infinite structure and serves as an upper bound on the transmittance for smaller-size apertures.

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Dependence of Granular Matrix Demagnetizing Factor on the Matrix Relative Size

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1083.32 ◽

2015 ◽

Vol 1083 ◽

pp. 32-36 ◽

Cited By ~ 1

Author(s):

Alexander Sandulyak ◽

Anna Sandulyak ◽

Petr Shkatov

Keyword(s):

Magnetic Permeability ◽

Relative Size ◽

Dramatic Effect ◽

Comparative Estimate ◽

Magnetic Filter ◽

Wide Range ◽

Demagnetizing Factor ◽

The Matrix ◽

Granular Matrix ◽

Operating Units

We note that for a wide range of porous, especially granular, ferromagnetics used as matrices of magnetic filter-separators, there is still an issue of defining their demagnetizing factor N which has a dramatic effect on the values of average magnetic permeability of these operating units of filter-separators. The work aims at filling the existent gaps in the issue, we supply N values depending on the relative size of such magnets as well as a respective generalizing phenomenological dependence which is characterized by an exponential realtion between the demagnetizing factor and relative size radical. The established relation allows obtaining real values of magnetic permeability of a short filter matrix thus providing an unbiased comparative estimate of its technological workability.

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