In this paper properties and dynamical behaviour of a theoretical biological model, the chemoton are discussed. The chemoton features the general, common properties of the…
Abstract
In this paper properties and dynamical behaviour of a theoretical biological model, the chemoton are discussed. The chemoton features the general, common properties of the unicellular living beings. Since the reaction‐kinetical function of the chemoton is governed by a set of nonlinear differential equations, the study of its dynamical behaviour required computer simulation. This was carried out by using CSMP programs. The results proved that the model is capable of stable functioning, growing and multiplication.
The purpose of this paper is to suggest a polynomial complexity method for determining the range of the active and reactive power consumed in AC uncertain parameter circuits whose…
Abstract
Purpose
The purpose of this paper is to suggest a polynomial complexity method for determining the range of the active and reactive power consumed in AC uncertain parameter circuits whose uncertain parameters are given as intervals.
Design/methodology/approach
First, the original problem is formulated as a corresponding interval quadratic range determination (IQRD) problem. Next, it is shown that the IQRD problem can be transformed equivalently into an interval linear range determination (ILRD) problem.
Findings
An efficient numerical method for solving the associated ILRD problem has been developed, capable of tackling the present active (or reactive) power range problem. It is based on the use of the outer solution y of an associated interval linear system defining the constraints in the ILRD problem.
Research limitations/implications
The method yields the exact active and reactive power range if the number of the components yi of y containing zero is relatively small (which is most often the case); otherwise, it provides tight outer bounds on the ranges sought.
Practical implications
The present method can be an alternative to the widely used Monte‐Carlo method since the former method provides exact (within rounding errors) results or tight outer approximations for lesser computation times.
Originality/value
To the best of the author's knowledge, the present paper suggests, for the first time, a simple interval analysis method of polynomial complexity for solving the problem considered which is inherently a NP‐hard problem (of exponential complexity).
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To suggest a polynomial complexity method for determining the range of real eigenvalues in the case of the generalized eigenvalue problem when the elements of the matrices…
Abstract
Purpose
To suggest a polynomial complexity method for determining the range of real eigenvalues in the case of the generalized eigenvalue problem when the elements of the matrices involved are independent intervals.
Design/methodology/approach
The basic approach is to make use of approximate interval solutions as regards the right and left eigenvectors of the eigenproblem considered, the so‐called outer solutions, in order to determine the range.
Findings
First, a new method for computing the outer solutions has been suggested. The main result of the paper, however, is the development of a simple method for determining the range of the real eigenvalues. Unlike the known general‐purpose methods that have exponential complexity, the present range determination method is much simpler as its complexity is only polynomial.
Research limitations/implications
The method is applicable if certain sufficient conditions reported in the paper are satisfied (an incomplete quadratic system is to have a positive solution and the signs of the outer solutions should satisfy a complete or partial invariance).
Practical implications
The method guarantees reliable numerical results when the original eigenproblems contain interval uncertainties as is, strictly speaking, most often the case in practice.
Originality/value
To the best of the author's knowledge, the present paper suggests, for the first time, a simple method of polynomial complexity for solving the problem considered which is inherently a NP‐hard problem (of exponential complexity).
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Mamta Mishra, Surya Prakash Singh and M. P. Gupta
The research in competitive facility location (CFL) is quite dynamic, both from a problem formulation and an algorithmic point of view. Research direction has changed immensely…
Abstract
Purpose
The research in competitive facility location (CFL) is quite dynamic, both from a problem formulation and an algorithmic point of view. Research direction has changed immensely over the years to address various competitive challenges. This study aims to explore CFL literature to highlight these research trends, important issues and future research opportunities.
Design/methodology/approach
This study utilises the Scopus database to search for related CFL models and adopts a five-step systematic approach for the review process. The five steps involve (1) Article Identification and keyword selection, (2) Selection criteria, (3) Literature review, (4) Literature analysis and (5) Research studies.
Findings
The paper presents a comprehensive review of CFL modelling efforts from 1981 to 2021 to provide a depth study of the research evolution in this area. The published articles are classified based on multiple characteristics, including the type of problem, type of competition, game-theoretical approaches, customer behaviour, decision space, type of demand, number of facilities, capacity and budget limitations. The review also highlights the popular problem areas and dedicated research in the respective domain. In addition, a second classification is also provided based on solution methods adopted to solve various CFL models and real-world case studies.
Originality/value
The paper covers 40 years of CFL literature from the perspective of the problem area, CFL characteristics and the solution approach. Additionally, it introduces characteristics such as capacity limit and budget constraint for the first time for classification purposes.
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Wenjun Liu and Bozhi Yang
The goal of this review paper is to provide information on several commonly used thermography techniques in semiconductor and micro‐device industry and research today.
Abstract
Purpose
The goal of this review paper is to provide information on several commonly used thermography techniques in semiconductor and micro‐device industry and research today.
Design/methodology/approach
The temperature imaging or mapping techniques include thin coating methods such as liquid crystal thermography and fluorescence microthermography, contact mechanical methods such as scanning thermal microscopy, and optical techniques such as infrared microscopy and thermoreflectance. Their principles, characteristics and applications are discussed.
Findings
Thermal issues play an important part in optimizing the performance and reliability of high‐frequency and high‐packing density electronic circuits. To improve the performance and reliability of microelectronic devices and also to validate thermal models, accurate knowledge of local temperatures and thermal properties is required.
Originality/value
The paper provides readers, especially technical engineers in industry, a general knowledge of several commonly used thermography techniques in the semiconductor and micro‐device industries.
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Keywords
The year 2020 brought a series of previously unknown experiences, events, and life situations to the world. Fear of unknown, uncertainty, unpredictability, and dramatic changes…
Abstract
The year 2020 brought a series of previously unknown experiences, events, and life situations to the world. Fear of unknown, uncertainty, unpredictability, and dramatic changes have had a strong impact on all strata and segments of society. We assume that global happenings of the last decade, climate change, pandemic followed by its related strict restrictions mean a determining event for youngsters which fundamentally shapes their lifestyle, future prospects, problem perception, and their generational characteristics as well. In our study, we examine the real-life situation of students at the University of Szeged from numerous aspects, with particular regard to the possible generation-transforming role of climate and quarantine situation, and we also scrutinize to what extent our previous estimations can be verified with data. The online data collection was carried out in the spring of 2021, the sample contains 1195 members. As the result of the data analysis, we indicated that the coronavirus epidemic does not play a leading role in the problem perception of the students, however, their responses about their self-characterization testify on increased perception of crisis phenomena. Although public life and public discourse have been thematized by the coronavirus epidemic since spring 2020, incompetence of politicians and global environmental change are the most serious problems for the students. In the basic dimensions of youth vulnerability namely in the field of education, leisure, and finance, the satisfaction of the students are the lowest. As a result of the restrictive measures, the online activity of the students has further strengthened; instead of silence and apolitical behavior, the students are characterized by a strong public–political interest, increased sensitivity to global problems in the third wave of the pandemic.
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The landscape of European cities is by no means homogeneous. Nonetheless, the same type of conflict has repeatedly occurred in different places in the last few years: From Seville…
Abstract
The landscape of European cities is by no means homogeneous. Nonetheless, the same type of conflict has repeatedly occurred in different places in the last few years: From Seville to Vienna, from Cologne to St. Petersburg, planned high-rise buildings for inner city districts have provoked fervent arguments and debates. Whether and how European cities should integrate more high-rise buildings is a highly controversial question. This chapter focuses on strategies of vertical construction and related debates about the cityscape in both Paris and Vienna. By studying the urban constellations of Paris and Vienna, it can be shown that what may look comparable at first glance is the outcome of highly different strategies and histories.
Although both cities define themselves to a wide degree with reference to historic structures, the image of tall buildings varies drastically in these cities, which correlates with these cities’ diverse histories and hence experiences with high-rise buildings. Path dependencies and the ways individual cities receive international trends are crucial to understanding processes of urbanization. Based on in-depth interviews with various urban actors and other relevant qualitative data, this chapter aims to demonstrate that a city’s high-rise strategy cannot be attributed to any single factor; rather, it is the result of a complex interplay between various aspects and actors, which crucially includes present and past struggles over cityscapes and therefore over urban spaces.
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A finite‐element formulation is developed to analyze nonlinear electromagnetic devices in steady‐state conditions under specified alternating terminal voltages. The circuit…
Abstract
A finite‐element formulation is developed to analyze nonlinear electromagnetic devices in steady‐state conditions under specified alternating terminal voltages. The circuit equations are used to express current densities in terms of the unknown vector potential, so that only one nonlinear field equation must be solved. The mathematical formulation and the finite‐element and Fourier approximations are developed and the numerical algorithm used to solve the resulting block system is discussed. Finally, an application of the method to analyze an electromagnet with shading coils is presented.
S. RATNAJEEVAN H. HOOLE and Z.J. CENDES
Non‐divergent and irrotational projection operators are proposed and implemented in a FORTRAN program for the direct vector solution of Laplacian electric and magnetic fields…
Abstract
Non‐divergent and irrotational projection operators are proposed and implemented in a FORTRAN program for the direct vector solution of Laplacian electric and magnetic fields, using finite element approximations. It is shown that this approach, in addition to giving continuous electric and magnetic fields, yields far more accurate results compared to the regular potential formulations. Some properties of the matrices are derived.
N.A. Golias, C.S. Antonopoulos, T.D. Tsiboukis and E.E. Kriezis
A finite element formulation for the solution of 3D eddy current problems in terms of the electric intensity E is presented. A weak formulation, based on a Galerkin weighted…
Abstract
A finite element formulation for the solution of 3D eddy current problems in terms of the electric intensity E is presented. A weak formulation, based on a Galerkin weighted residual procedure, is presented and edge elements, that impose only tangential continuity across element interfaces of the approximated field, are employed for the discretization of the problem with the finite element method. The reliability and validity of the suggested method is verified by its application to the calculation of the 3D eddy current distribution in two conducting systems.