The Mathematical Modeling of Utility Boilers at IST

2000 ◽  
Author(s):  
P. J. Coelho ◽  
J. L. T. Azevedo ◽  
L. M. R. Coelho
Keyword(s):  
Mathematical Modeling ◽  
Combustion Chamber ◽  
Difficult Problem ◽  
The Other ◽  
Utility Boilers ◽  
Coal Reburning ◽  
Physical Phenomena

Abstract The mathematical modeling of utility boilers is a difficult problem due to the multiplicity of physical phenomena involved and to the interaction between different phenomena. However, reliable models are extremely useful since they can be used to design new equipment, and to optimize and retrofit units in operation. In this paper a survey of the work carried out at Institute superior Técnico (IST) in Lisbon is reported. Only the work based on comprehensive models, i.e., those accounting for all the relevant physical phenomena taking place in the combustion chamber is addressed. The models employed are briefly outlined. Then, four examples of application are given, two of them for coal-fired boilers where the effect of low NOx burners and coal over coal reburning is investigated, and the other two for oil-fired boilers where parallelization of the code and simulation of the convection chamber are reported.

Localized interaction solution and its dynamics of the extended Hirota–Satsuma–Ito equation

2021 ◽  
pp. 2150313
Author(s):  
Jian-Ping Yu ◽  
Wen-Xiu Ma ◽  
Chaudry Masood Khalique ◽  
Yong-Li Sun
Keyword(s):  
Numerical Simulations ◽  
Rogue Wave ◽  
The Other ◽  
Hirota Bilinear Method ◽  
Bilinear Method ◽  
Interaction Solutions ◽  
Physical Phenomena ◽  
Wave Phenomena ◽  
Hirota Bilinear ◽  
Ito Equation

In this research, we will introduce and study the localized interaction solutions and th eir dynamics of the extended Hirota–Satsuma–Ito equation (HSIe), which plays a key role in studying certain complex physical phenomena. By using the Hirota bilinear method, the lump-type solutions will be firstly constructed, which are almost rationally localized in all spatial directions. Then, three kinds of localized interaction solutions will be obtained, respectively. In order to study the dynamic behaviors, numerical simulations are performed. Two interesting physical phenomena are found: one is the fission and fusion phenomena happening during the procedure of their collisions; the other is the rogue wave phenomena triggered by the interaction between a lump-type wave and a soliton wave.

scholarly journals Modeling and Controlling the Cooling System of an IC Vehicle

2021 ◽  
pp. 80-85
Author(s):  
C. Mureșan ◽  
◽  
G. Harja
Keyword(s):  
Mathematical Modeling ◽  
Heat Exchangers ◽  
High Performance ◽  
Cooling System ◽  
Control Strategies ◽  
Positive Influence ◽  
Control Algorithms ◽  
Performance Control ◽  
Ic Engines ◽  
Physical Phenomena

The performance and efficiency of internal combustion (IC) engines can be greatly improved by using a high-performance cooling system. This can be achieved by implementing robust control strategies and, also by building the cooling system with high-performance elements. The mechanical execution elements can be replaced with electrically controllable elements such as the pump and the thermostat valve. This will have a positive influence on the degree of controllability of the system. In order to develop high-performance control algorithms, it is necessary to have a model that best reflects the behaviors of the physical system. Thus, this paper presents a mathematical modeling approach for the cooling system using the principles of heat exchangers and the physical phenomena present in them.

scholarly journals Reproducibility of parallel preconditioned conjugate gradient in hybrid programming environments

2020 ◽  
Vol 34 (5) ◽  
pp. 502-518
Author(s):  
Roman Iakymchuk ◽  
Maria Barreda Vayá ◽  
Stef Graillat ◽  
José I Aliaga ◽  
Enrique S Quintana-Ortí
Keyword(s):  
Conjugate Gradient ◽  
The Other ◽  
Preconditioned Conjugate Gradient ◽  
Programming Environment ◽  
Systems Of Equations ◽  
Intermediate Precision ◽  
Programming Environments ◽  
Physical Phenomena ◽  
Linear Systems Of Equations ◽  
Number Of Iterations

The Preconditioned Conjugate Gradient method is often employed for the solution of linear systems of equations arising in numerical simulations of physical phenomena. While being widely used, the solver is also known for its lack of accuracy while computing the residual. In this article, we propose two algorithmic solutions that originate from the ExBLAS project to enhance the accuracy of the solver as well as to ensure its reproducibility in a hybrid MPI + OpenMP tasks programming environment. One is based on ExBLAS and preserves every bit of information until the final rounding, while the other relies upon floating-point expansions and, hence, expands the intermediate precision. Instead of converting the entire solver into its ExBLAS-related implementation, we identify those parts that violate reproducibility/non-associativity, secure them, and combine this with the sequential executions. These algorithmic strategies are reinforced with programmability suggestions to assure deterministic executions. Finally, we verify these approaches on two modern HPC systems: both versions deliver reproducible number of iterations, residuals, direct errors, and vector-solutions for the overhead of less than 37.7% on 768 cores.

Guest Editor’s Introduction: Software Mathematical Models for Human Understanding

2020 ◽  
Vol 30 (10) ◽  
pp. 1371-1374
Author(s):  
Iaakov Exman
Keyword(s):  
Neural Networks ◽  
Deep Learning ◽  
Systems Design ◽  
Difficult Problem ◽  
The Other ◽  
Software Systems ◽  
Special Issue ◽  
Software Developers ◽  
Human Understanding ◽  
Introductory Paper

The unrelenting trend of larger and larger sizes of Software Systems and data has made software comprehensibility an increasingly difficult problem. However, a tacit consensus that human understanding of software is essential for most software related activities, stimulated software developers to embed comprehensibility in their systems’ design. On the other hand, recent empirical successes of Deep Learning neural networks, in several application areas, seem to challenge the tacit consensus: is software comprehensibility a necessity, or just superfluous? This introductory paper, to the 2020 special issue on Theoretical Software Engineering, offers reasons justifying our standpoint on the referred controversy. This paper also points out to specific techniques enabling Human Understanding of software systems relevant to this issue’s papers.

Metaphysics of Mind

Philosophy ◽  
2010 ◽  
Author(s):  
Darragh Byrne
Keyword(s):  
Philosophy Of Mind ◽  
Propositional Attitudes ◽  
Good Deal ◽  
Mental States ◽  
The Other ◽  
Intrinsic Properties ◽  
Psychological Phenomena ◽  
The Mind ◽  
Physical Phenomena ◽  
Metaphysics Of Mind

Philosophy of mind addresses fundamental questions about mental or psychological phenomena. The question held by many to be most fundamental of all is a metaphysical one, often labeled the “mind-body problem,” which concerns the relation between minds and material or physical phenomena. Physicalists (and/or materialists) contend that mental phenomena are physical, or at least that they may be accounted for in terms of physical phenomena (brains, for example). Dualists deny this, maintaining that mental phenomena have fundamentally nonphysical natures, so that to account for minds we must assume the existence of nonphysical substances or properties. Nowadays physicalism is more widely espoused than dualism, but physicalists differ over which physical states/properties should be considered relevant, and over the precise nature of the relation between physical and mental phenomena. This is one of four bibliography entries on the philosophy of mind, and this particular entry concentrates on this metaphysical issue of the relation between mental and physical/material phenomena. Inevitably, there is a good deal of overlap between this and topics covered in the other three entries. For example, this entry includes authors who attack physicalism by arguing that it cannot account for the distinctive phenomenal qualities of conscious experiences; but that line of antiphysicalist argument features even more prominently in the entry on consciousness. Moreover, the other entries feature various issues that might perfectly properly be categorized as concerning the metaphysics of mind: for example, the debate between internalists—philosophers who hold that propositional attitudes (mental states such as beliefs and desires, which have representational contents) are intrinsic properties of minds/brains—and externalists, who think of certain attitudes as extrinsic or relational, is surely a question about the metaphysics of mind: but this is discussed in the entry on intentionality instead of here.

scholarly journals The Analytical Analysis of Time-Fractional Fornberg–Whitham Equations

Mathematics ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 987 ◽  
Author(s):  
A. A. Alderremy ◽  
Hassan Khan ◽  
Rasool Shah ◽  
Shaban Aly ◽  
Dumitru Baleanu
Keyword(s):  
Mathematical Modeling ◽  
Analytical Solution ◽  
Fractional Order ◽  
Analytical Solutions ◽  
Decomposition Method ◽  
Analytical Techniques ◽  
Whitham Equations ◽  
Suggested Technique ◽  
Approximate Analytical Solutions ◽  
Physical Phenomena

This article is dealing with the analytical solution of Fornberg–Whitham equations in fractional view of Caputo operator. The effective method among the analytical techniques, natural transform decomposition method, is implemented to handle the solutions of the proposed problems. The approximate analytical solutions of nonlinear numerical problems are determined to confirm the validity of the suggested technique. The solution of the fractional-order problems are investigated for the suggested mathematical models. The solutions-graphs are then plotted to understand the effectiveness of fractional-order mathematical modeling over integer-order modeling. It is observed that the derived solutions have a closed resemblance with the actual solutions. Moreover, using fractional-order modeling various dynamics can be analyzed which can provide sophisticated information about physical phenomena. The simple and straight-forward procedure of the suggested technique is the preferable point and thus can be used to solve other nonlinear fractional problems.

Asymptotic behaviour near past null infinity for scattering problems

1977 ◽  
Vol 55 (10) ◽  
pp. 855-860 ◽  
Author(s):  
Martin Walker
Keyword(s):  
Asymptotic Behaviour ◽  
Impact Parameter ◽  
Approximation Scheme ◽  
Flat Space ◽  
Difficult Problem ◽  
Space Time ◽  
The Other ◽  
Null Infinity ◽  
Scattering Problems ◽  
Gravitational Systems

The following problem is treated: two particles move toward each other from infinity with equal but opposite velocities and finite impact parameter. Each particle is deflected by the field of the other. The particles recede, finally, back out to infinity. Electromagnetic and gravitational interactions between the particles are considered. It is shown, in both cases, that the use of retarded interactions, in an approximation scheme which begins with no interaction in flat space-time, guarantees the absence of incoming radiation. This result may be of relevance to the much more difficult problem of the description of bounded, isolated, gravitational systems.

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