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N. Banagaaya, W.H.A. Schilders, G. Alì and C. Tischendorf
Model order reduction (MOR) has been widely used in the electric networks but little has been done to reduce higher index differential algebraic equations (DAEs). The…
Model order reduction (MOR) has been widely used in the electric networks but little has been done to reduce higher index differential algebraic equations (DAEs). The paper aims to discuss these issues.
Most methods first do an index reduction before reducing a higher DAE but this can lead to a loss of physical properties of the system.
The paper presents a MOR method for DAEs called the index-aware MOR (IMOR) which can reduce a DAE while preserving its physical properties such as the index. The feasibility of this method is tested on real-life electric networks.
MOR has been widely used to reduce large systems from electric networks but little has been done to reduce higher index DAEs. Most methods first do an index reduction before reducing a large system of DAEs but this can lead to a loss of physical properties of the system. The paper presents a MOR method for DAEs called the IMOR which can reduce a DAE while preserving its physical properties such as the index. The feasibility of this method is tested on real-life electric networks.
Samuel Kvasnicka, Thomas Bauernfeind, Paul Baumgartner and Riccardo Torchio
The purpose of this paper is to show that the computation of time-periodic signals for coupled antenna-circuit problems can be substantially accelerated by means of the…
The purpose of this paper is to show that the computation of time-periodic signals for coupled antenna-circuit problems can be substantially accelerated by means of the single shooting method. This allows an efficient analysis of nonlinearly loaded coupled loop antennas for near field communication (NFC) applications.
For the modelling of electrically small coupled field-circuit problems, the partial element equivalent circuit (PEEC) method shows to be very efficient. For analysing the circuit-like description of the coupled problem, this paper developed a generalised modified nodal analysis (MNA) and applied it to specific NFC problems.
It is shown that the periodic steady state (PSS) solution of the resulting differential-algebraic system can be computed very time efficiently by the single shooting method. A speedup of roughly 114 to conventional transient approaches can be achieved.
The proposed approach appears to be an efficient alternative for the computation of time PSS solutions for nonlinear circuit problems coupled with discretised conductive structures, where the homogeneous solution is not of interest.
The present paper explores the implementation and application of the shooting method for nonlinearly loaded coupled antenna-circuit problems based on the PEEC method and shows the efficiency of this approach.
- Circuit analysis
- Transient analysis
- Time-domain modelling
- Equivalent circuit model
- Computational electromagnetics
- Field circuit models
- Near field communication
- Nonlinear resistive loads
- Full-wave rectifier
- Partial element equivalent circuit method
- Modified nodal analysis
- Differential-algebraic equation
- Backward differentiation formula
- Single shooting method
Sebastian Schöps, Herbert De Gersem and Thomas Weiland
The purpose of this paper is to review the mutual coupling of electromagnetic fields in the magnetic vector potential formulation with electric circuits in terms of…
The purpose of this paper is to review the mutual coupling of electromagnetic fields in the magnetic vector potential formulation with electric circuits in terms of (modified) nodal and loop analyses. It aims for an unified and generic notation.
The coupled formulation is derived rigorously using the concept of winding functions. Strong and weak coupling approaches are proposed and examples are given. Discretization methods of the partial differential equations and in particular the winding functions are discussed. Reasons for instabilities in the numerical time domain simulation of the coupled formulation are presented using results from differential-algebraic-index analysis.
This paper establishes a unified notation for different conductor models, e.g. solid, stranded and foil conductors and shows their structural equivalence. The structural information explains numerical instabilities in the case of current excitation.
The presentation of winding functions allows to generically describe the coupling, embed the circuit equations into the de Rham complex and visualize them by Tonti diagrams. This is of value for scientists interested in differential geometry and engineers that work in the field of numerical simulation of field-circuit coupled problems.
WE begin a new year, in which we wish good things for all who work in libraries and care for them, in circumstances which are not unpropitious. At times raven voices…
WE begin a new year, in which we wish good things for all who work in libraries and care for them, in circumstances which are not unpropitious. At times raven voices prophesy the doom of a profession glued to things so transitory as books are now imagined to be, by some. Indeed, so much is this a dominant fear that some librarians, to judge by their utterances, rest their hopes upon other recorded forms of knowledge‐transmission; forms which are not necessarily inimical to books but which they think in the increasing hurry of contemporary life may supersede them. These fears have not been harmful in any radical way so far, because they may have increased the librarian's interest in the ways of bringing books to people and people to books by any means which successful business firms use (for example) to advertise what they have to sell. The modern librarian becomes more and more the man of business; some feel he becomes less and less the scholar; but we suggest that this is theory with small basis in fact. Scholars are not necessarily, indeed they can rarely be, bookish recluses; nor need business men be uncultured. For men of plain commonsense there need be few ways of life that are so confined that they exclude their followers from other ways and other men's ideas and activities. And, as for the transitoriness of books and the decline of reading, we ourselves decline to acknowledge or believe in either process. Books do disappear, as individuals. It is well that they do for the primary purpose of any book is to serve this generation in which it is published; and, if there survive books that we, the posterity of our fathers, would not willingly let die, it is because the life they had when they were contemporary books is still in them. Nothing else can preserve a book as a readable influence. If this were not so every library would grow beyond the capacity of the individual or even towns to support; there would, in the world of readers, be no room for new writers and their books, and the tragedy that suggests is fantastically unimaginable. A careful study, recently made of scores of library reports for 1951–52, which it is part of our editorial duty to make, has produced the following deductions. Nearly every public library, and indeed other library, reports quite substantial increases in the use made of it; relatively few have yet installed the collections of records as alternatives to books of which so much is written; further still, where “readers” and other aids to the reading of records, films, etc., have been installed, the use of them is most modest; few librarians have a book‐fund that is adequate to present demands; fewer have staffs adequate to the demands made upon them for guidance by the advanced type of readers or for doing thoroughly the most ordinary form of book‐explanation. It is, in one sense a little depressing, but there is the challenging fact that these islands contain a greater reading population than they ever had. One has to reflect that of our fifty millions every one, including infants who have not cut their teeth, the inhabitants of asylums, the illiterate—and, alas, there are still thousands of these—and the drifters and those whose vain boast is that “they never have time to read a book”—every one of them reads six volumes a year. A further reflection is that public libraries may be the largest distributors, but there are many others and in the average town there may be a half‐dozen commercial, institutional and shop‐libraries, all distributing, for every public library. This fact is stressed by our public library spending on books last year at some two million pounds, a large sum, but only one‐tenth of the money the country spent on books. There are literally millions of book‐readers who may or may not use the public library, some of them who do not use any library but buy what they read. The real figure of the total reading of our people would probably be astronomical or, at anyrate, astonishing.
These projects aim to improve library services for users in the future by combining Link Open Data (LOD) technology with data visualization. It displays and analyses…
These projects aim to improve library services for users in the future by combining Link Open Data (LOD) technology with data visualization. It displays and analyses search results in an intuitive manner. These services are enhanced by integrating various LOD technologies into the authority control system.
The technology known as LOD is used to access, recycle, share, exchange and disseminate information, among other things. The applicability of Linked Data technologies for the development of library information services is evaluated in this study.
Apache Hadoop is used for rapidly storing and processing massive Linked Data data sets. Apache Spark is a free and open-source data processing tool. Hive is a SQL-based data warehouse that enables data scientists to write, read and manage petabytes of data.
The distributed large data storage system Apache HBase does not use SQL. This study’s goal is to search the geographic, authority and bibliographic databases for relevant links found on various websites. When data items are linked together, all of the data bits are linked together as well. The study observed and evaluated the tools and processes and recorded each data item’s URL. As a result, data can be combined across silos, enhanced by third-party data sources and contextualized.