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DRYING OF POWER-TRANSFORMER INSULATION

IEE PROCEEDINGS-C GENERATION TRANSMISSION AND DISTRIBUTION 1982年第5期129卷 228-232页

作者： ASEM, AS HOWE, AF UNIV NOTTINGHAM DEPT ELECT & ELECTR ENGNNOTTINGHAM NG7 2RDENGLAND

To ensure that large high-voltage power transformers will operate reliably for years without requiring unscheduled maintenance, manufacturers thoroughly dry the insulation after manufacture and before commissioning. Using conventional monitoring procedures, it is difficult to establish the residual moisture concentration throughout the *** paper introduces a computational technique which has the potential of calculating accurately the moisture levels in the windings after various periods drying. The method takes into account the evaporative transfer of moisture from the winding surface to the drying medium and may be applied to all drying cycles which incorporate periods of air, vapour-phase or oil-spray heating and *** demonstrate the accuracy of the method the drying of a model layer winding was predicted and the results were compared with measurements. The excellent correlation of the results is displayed in the paper.

关键词： transformer windings moisture transformer insulation drying Transformers and reactors moisture levels power transformers windings high-voltage power transformers computational technique power transformer insulation

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SIMPLE TWO-DIMENSIONAL NUMERICAL-SOLUTION METHOD FOR SAW-SEMICONDUCTOR DEVICE SIMULATIONS

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ELECTRONICS LETTERS 1989年第7期25卷 465-467页

作者： HAARTSEN, JC VENEMA, A Delft Univ. of Technol. Netherlands

A computational technique to determine the electrical properties of SAW-semiconductor devices is presented. The contribution of the acoustic waves is reduced to a surface charge at the interface between the piezoelectric layer and the semiconducting substrate. In this way the electrical problem can be solved with numerical techniques commonly used for device modelling.

关键词： SAW-semiconductor devices computational technique device modelling electrical properties numerical methods numerical techniques piezoelectric layer semiconductor device models surface acoustic wave devices surface charge two-dimensional numerical solution method

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Using symbolic computation to exactly solve for the Bogoyavlenskii's generalized breaking soliton equation

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COMPUTERS & MATHEMATICS WITH APPLICATIONS 1997年第4期33卷 35-37页

作者： Gao, YT Tian, B BEIJING UNIV AERONAUT & ASTRONAUT DEPT APPL MATH & PHYSBEIJING 100083PEOPLES R CHINA

In this paper, the symbolic computation systems help us find some exact solutions for the Bogoyavlenskii's generalized breaking soliton equation, which are the sums of the arbitrary functions of time and parameter... 详细信息

关键词： breaking soliton equations symbolic computation computational technique mathematical methods in physics exact solutions

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Energy and diffusion of hydrogen atoms in titanium substituted vanadium hydrides from ab initio calculations

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MATERIALS CHEMISTRY AND PHYSICS 2014年第3期148卷 533-539页

作者： Kim, Jiwoong Yoo, Jeong-Hyun Cho, Sung-Wook Korea Inst Geosci & Mineral Resources Taejon 305350 South Korea

The equilibrium lattice parameters, formation energy, and diffusion behavior of hydrogen atoms in vanadium hydrides with and without Ti substitution were calculated by ab initio calculations and quantum correction by zero point energy was achieved using phonon vibration calculations. The calculated formation energies indicated that Ti substitution induces instability in the vanadium hydrides and electron density calculations showed that hydrogen has strong electrochemical affinity with Ti. The diffusion behavior was examined by the nudged elastic band (NEB) method to investigate the transition states of the hydrides. It revealed that Ti substitution is shown to reduce the diffusion coefficient and this effect was decreased with increasing temperature. The results of this study are expected to provide useful guidelines for understanding hydrogen absorption and desorption properties of hydrogen storage materials. (C) 2014 Published by Elsevier B.V.

关键词： computational technique Thermodynamic properties Diffusion Electronic structure

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Design, Synthesis and Optoelectronic Properties of Unsymmetrical Oxadiazole Based Indene Substituted Derivatives as Deep Blue Fluoroscent Materials

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JOURNAL OF FLUORESCENCE 2015年第5期25卷 1323-1330页

作者： Belavagi, Ningaraddi S. Deshapande, Narahari Pujar, G. H. Wari, M. N. Inamdar, S. R. Khazi, Imtiyaz Ahmed M. Karnatak Univ Dept Chem Dharwad 58003 Karnataka India Karnatak Univ Dept Phys Dharwad 58003 Karnataka India

A series of novel unsymmetrically substituted indene-oxadiazole derivatives (3a-f) have been designed and synthesized by employing palladium catalysed Suzuki cross coupling reaction in high yields. The structural integrity of all the novel compounds was established by H-1, C-13 NMR and LC/MS analysis. These compounds are amorphous in nature and are remarkably stable to long term storage under ambient conditions. The optoelectronic properties have been studied in detail using UV-Vis absorption and Fluorescence spectroscopy. All compounds emit intense blue to green-blue fluoroscence with high quantum yields. Time resolved measurments have shown life times in the range of 1.28 to 4.51 ns. The density functional theory (DFT) calculations were carried out for all the molecules to understand their structure-property relationships. Effect of concentration studies has been carried out in different concentrations for both absorption and emission properties and from this we have identified the optimized fluoroscence concentrations for all these compounds. The indene substituted anthracene-oxadiazole derivative (3f) showed significant red shift (lambda(max) (emi) = 490 nm) and emits intense green-blue fluoroscence with largest stokes shift of 145 nm. This compound also exhibited highest fluoroscence life time (tau) of 4.51 ns, which is very close to the standard dye coumarin-540A (4.63 ns) and better than fluorescein-548 (4.10 ns). The results demonstrated that the novel unsymmetrical indene-substituted oxadiazole derivatives could play important role in organic optoelectronic applications, such as organic light-emitting diodes (OLEDs) or as models for investigating the fluorescent structure-property relationship of the indene-functionalized oxadiazole derivatives.

关键词： Amorphous materials Chemical synthesis Organic compounds Optical properties computational technique

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ASPECTS OF THE HARTLEY TRANSFORM

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PROCEEDINGS OF THE IEEE 1994年第3期82卷 381-387页

作者： BRACEWELL, RN Space Telecommun. & Radiosci. Lab. Stanford Univ. CA

Known in the signal processing literature mainly as a computational technique, the Hartley transform has proven to possess attributes in the physical world of experiment, especially in optics and microwaves. The Fourier transform, which has constituted the standard approach to spectral analysis, is understood both in the domain of numerical analysis and in the world of natural phenomena, gaining its central significance from the ubiquity of sinusoidal natural behavior;it also gains appeal from the convenience offered by complex variable analysis, which is a basic part of technical education. Computers, however, prefer real numbers, an attribute that first opened a niche for the Hartley transform. As applications have multiplied, and others open up, it will be helpful to understand the Hartley idea from more than one point of view. Several topics, including multidimensional transforms, the complex generalization, and microwave phase measurement by amplitude measurement only, are discussed with the intention of throwing light on the numerical and physical relationships between the Hartley and Fourier transforms.

关键词： Hartley transform amplitude measurement complex generalization computational technique microwave phase measurement microwaves multidimensional transforms numerical analysis phase measurement signal processing signal processing spectral analysis transforms

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A fully vectorial technique for scattering and propagation in three-dimensional stratified photonic structures

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OPTICAL AND QUANTUM ELECTRONICS 2001年第4-5期33卷 315-325页

作者： Paulus, M Martin, OJF ETH Zentrum Swiss Fed Inst Technol Electromagnet Fields & Microwave Elect Lab CH-8092 Zurich Switzerland IBM Corp Div Res Zurich Res Lab CH-8803 Ruschlikon Switzerland

We present a three-dimensional (3D) technique for computing light scattering and propagation in complex structures formed by scatterers embedded in a stratified background. This approach relies on the Green's tensor associated with the background and requires only the discretization of the scatterers, the entire stratified background being accounted for in the Green's tensor. Further, the boundary conditions at the edges of the computation window and at the different material interfaces in the stratified background are automatically fulfilled. Different examples illustrate the application of the technique to the modeling of photonic integrated circuits: waveguides with protrusions (single element 'grating') and notches. Subtle effects, like polarization crosstalks in an integrated optics device are also investigated.

关键词： computational technique eigenmodes Green's tensor integrated optics light propagation polarization scattering stratified media waveguides

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DEVELOPMENT OF FLOW AND HEAT TRANSFER DURING FILLING A PIPELINE WITH WATER AT THE PIPE WALL TEMPERATURE BELOW THE FREEZING POINT

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JOURNAL OF ENGINEERING PHYSICS AND THERMOPHYSICS 2016年第4期89卷 808-814页

作者： Kitanin, E. L. Smirnov, Yu. A. Lebedev, M. E. St Petersburg State Polytech Univ 29 Politekhn Skaya Str St Petersburg 195251 Russia Cent Boiler & Turbine Inst 3-6 Atamanskaya Str St Petersburg 191167 Russia

The paper presents the technique of computing flow and heat transfer of water in a pipeline whose initial temperature is lower than the freezing point of water. A feature of the method is the possibility of calculating the process from the moment of pouring water into a pipe on the inner surface of whose wall a layer of ice is being formed. The system of equations describing the process involves nonstationary energy equations for the water flow, ice layer, and for the pipe wall. It is solved for each section of the pipeline passed by water in a small time interval in the process of filling the pipe and further flow. The Beginning computer program has been created and implemented in the Visual Basic language for numerical analysis of the process. The calculations made with the aid of this program allow one to estimate the possibility of appearance of an ice plug in the pipeline at the given temperature, water flow rate, pipeline diameter, and conditions of external heat transfer of water flow in the pipeline.

关键词： freezing of water filling in a pipeline computational technique ice formation

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Infiltration effects on a two-dimensional molecular dynamics model of landslides

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NATURAL HAZARDS 2014年第1期73卷 37-62页

作者： Martelloni, Gianluca Bagnoli, Franco Ctr Study Complex Dynam CSDC Dept Phys & Astron I-50019 Sesto Fiorentino FI Italy Ist Nazl Fis Nucl Sez Firenze I-50125 Florence Italy

We propose a two-dimensional computational model for deep landslides triggered by rainfall, based on interacting particles or grains. The model describes a vertical section of a fictitious granular material along a slope, in order to study the behavior of a wide-thickness landslide. The triggering of the landslide is caused by the exceeding of two conditions: a threshold speed and a condition on the static friction of the particles, the latter based on the Mohr-Coulomb failure criterion (Coulomb in Mem Acad R Div Sav 7:343-387, 1776;Mohr in Abhandlungen aus dem Gebiete der Technischen Mechanik. Ernst, Berlin, 1914). The interparticle interactions are represented as a potential that, in the absence of suitable experimental data and due to the arbitrariness of the grain dimension, is modeled similarly to the Lennard-Jones' one (Lennard-Jones in Proc R Soc Lond A 106(738):463-477, 1924), i.e., with an attractive and a repulsive part. For the updating of the particle positions, we use a molecular dynamics method, which is quite suitable for this type of systems (Herrmann and Luding in Continuum Mech Thermodyn 10:189-231, 1998). An infiltration scheme is introduced for modeling the increasing pore pressure due to the rainfall. Finally, we also introduce the viscosity in the dynamical equations of motion. The statistical characterization and dynamical behavior of the results of simulations are quite satisfactory relative to real landslides: We obtain a power law distribution of landslide triggering times, and the velocity patterns are typical of real cases, including the acceleration progression. Therefore, we can claim that this type of modeling can represent a new method to simulate landslides triggered by rainfall.

关键词： Landslide Infiltration model Molecular dynamics computational technique

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MONTE CARLO PATH-INTEGRAL CALCULATIONS FOR TWO-POINT BOUNDARY-VALUE PROBLEMS

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NUMERISCHE MATHEMATIK 1967年第2期10卷 110-+页

作者： TSUDA, T ICHIDA, K KIYONO, T Department of Electronics Kyoto University Kyoto Japan

A computational technique based on the method of path integral is studied with a view to finding approximate solutions of a class of two-point boundary-value problems. These solutions are “rough” solutions by Monte Carlo sampling. From the computational point of view, however, once these rough solutions are obtained for any nonlinear cases, they serve as good starting approximations for improving the solutions to higher accuracy. Numerical results of a few examples are also shown.

关键词： Approximate Solution Mathematical Method computational technique Monte Carlo Sampling computational Point

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