I‐V characteristics of GaAs n‐i‐n structures are calculated by considering impact ionization of carriers. Impact ionization at reverse‐biased n‐i junction becomes a cause of steep…
Abstract
I‐V characteristics of GaAs n‐i‐n structures are calculated by considering impact ionization of carriers. Impact ionization at reverse‐biased n‐i junction becomes a cause of steep current rise when an acceptor density in the i‐layer is high. It is shown that an optimum acceptor density exists to keep a good isolation. Photoconduction transients of GaAs n‐i‐n structures are also simulated, and are shown to be strongly affected by existence of n‐i junctions.
In the course of development of human communities towards industrially advanced societies of today, there have been changes not only in economic conditions in the majority of…
Abstract
In the course of development of human communities towards industrially advanced societies of today, there have been changes not only in economic conditions in the majority of fields of human activity but also in the ways of providing for food, which went hand in hand with changes in living conditions. Large‐scale industrial production has brought about major changes in the way of life of the population. The development of industrial agglomerations results in a growing number of city dwellers, most of whom have no chance of producing foodstuffs of their own in kind. The distance between residential and industrial areas has been growing, the number of employed women has risen considerably. These are but a few factors affecting the way of boarding, particularly in households.
In systems theory, authors such as Klir, Miller, Yang, Lin and Ma, Backlund, etc. have developed different definitions of the system concept in function of both the type of…
Abstract
In systems theory, authors such as Klir, Miller, Yang, Lin and Ma, Backlund, etc. have developed different definitions of the system concept in function of both the type of variables used and the type of connection between variables. The concept of the subsystem, however, tends not to vary substantially from author to author, and this leads to a new system definition based on the subsystem concept, analysing the possible cases of interaction between subsystems and obtaining results for the overall system from an analysis of its subsystems.
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D.E. Clippinger and G.J. Morris
THE use of liquid oxygen as an oxidizer for various fuels in liquid rocket propellent systems is not new. Professor Goddard used liquid oxygen in his rocket experiments and the…
Abstract
THE use of liquid oxygen as an oxidizer for various fuels in liquid rocket propellent systems is not new. Professor Goddard used liquid oxygen in his rocket experiments and the well known German V‐2 rockets used this material as an oxidizer. However, its effect on non‐metallic materials ordinarily used in rocket systems was not investigated until recent years. This investigation was prompted by phenomena which had been experienced by rocket engine and rocket aircraft manufacturers and by suppliers of the material. It was observed that when some organic materials came in intimate contact with liquid oxygen they became prone to detonation when subjected to certain impact energies. This was undoubtedly due to the formation of unstable organo‐peroxide compounds which when impacted released high levels of energy resulting in an explosion. Specifically, when liquid oxygen was accidently spilled on asphalt and inadvertently stepped on, the asphalt would often explode. Also, leather gaskets immersed in liquid oxygen and subjected to surge impact detonated with disastrous effects.
Lorenzo Codecasa, Federico Moro and Piergiorgio Alotto
This paper aims to propose a fast and accurate simulation of large-scale induction heating problems by using nonlinear reduced-order models.
Abstract
Purpose
This paper aims to propose a fast and accurate simulation of large-scale induction heating problems by using nonlinear reduced-order models.
Design/methodology/approach
A projection space for model order reduction (MOR) is quickly generated from the first kernels of Volterra’s series to the problem solution. The nonlinear reduced model can be solved with time-harmonic phasor approximation, as the nonlinear quadratic structure of the full problem is preserved by the projection.
Findings
The solution of induction heating problems is still computationally expensive, even with a time-harmonic eddy current approximation. Numerical results show that the construction of the nonlinear reduced model has a computational cost which is orders of magnitude smaller than that required for the solution of the full problem.
Research limitations/implications
Only linear magnetic materials are considered in the present formulation.
Practical implications
The proposed MOR approach is suitable for the solution of industrial problems with a computing time which is orders of magnitude smaller than that required for the full unreduced problem, solved by traditional discretization methods such as finite element method.
Originality/value
The most common technique for MOR is the proper orthogonal decomposition. It requires solving the full nonlinear problem several times. The present MOR approach can be built directly at a negligible computational cost instead. From the reduced model, magnetic and temperature fields can be accurately reconstructed in whole time and space domains.
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Strategic management—the infusion of strategic principles in the running of a business—has demonstrated impressive power by dramatically improving the performance of a number of…
Abstract
Strategic management—the infusion of strategic principles in the running of a business—has demonstrated impressive power by dramatically improving the performance of a number of major companies that implemented it. (See Exhibit 1.) This concept, born in the early Seventies, is now experiencing the adolescent struggles of what Gail Sheehy, the author of Passages, calls, “gaining authenticity” and “ego strength.” Now, an era of self assurance, authority and leadership is at hand.
This paper outlines some of the factors which are important in helping or hindering women with learning disabilities to experience their sexuality in a positive and healthy way…
Abstract
This paper outlines some of the factors which are important in helping or hindering women with learning disabilities to experience their sexuality in a positive and healthy way. Based on direct experience, the paper presents the factors which must be present for women with learning disabilities to enjoy their sexuality: making choices, giving consent, receiving information, experiencing mutuality, experiencing pleasure, having self‐esteem and having recourse to the law if abused. Conversely, the factors which need to be absent are coercion, oppression, guilt and shame, and unwanted physical consequences. The paper emphasises how important it is that women with learning disabilities and their supporters understand these factors.
Systems with the so‐called “additive” property are studied. This kind of system is an abstract in the language of systems theory of some useful structures in mathematics, such as…
Abstract
Systems with the so‐called “additive” property are studied. This kind of system is an abstract in the language of systems theory of some useful structures in mathematics, such as topology. Some mapping properties between additive systems are given and open questions are posed.
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W.B. Heginbotham, A. Pugh, D.W. Gatehouse and D. Law
The realisation of a practical generally versatile variable product assembly machine is still far from reality. However, in the same way that a generation 1 Industrial Robot can…
Abstract
The realisation of a practical generally versatile variable product assembly machine is still far from reality. However, in the same way that a generation 1 Industrial Robot can achieve high levels of versatility within certain restricted activities e. g. paint spraying ‐ spot welding etc., then by the correct choice of product and product design high levels of versatility can be achieved with assembly machines.
In this paper, we introduce the concept of a supporting set for a general system. We study basic properties of supporting sets for a general system, supporting sets for subsytems…
Abstract
In this paper, we introduce the concept of a supporting set for a general system. We study basic properties of supporting sets for a general system, supporting sets for subsytems of a system, homomorphic images of supporting sets for a system, and supporting sets for free sums and direct sums of systems.