La production des aciers inoxydables: Histoire de son développement et des procédés de fabrication. Partie III. Évolutions des méthodes de coulée et de mise en forme des aciers inoxydables

2020 ◽  
Vol 108 (1) ◽  
pp. 105 ◽  
Author(s):  
Jean Saleil ◽  
Marc Mantel ◽  
Jean Le Coze
Keyword(s):  
Considerable Simplification

La coulée des aciers inoxydables, autrefois en lingots, s’effectue aujourd’hui par coulée continue. Ce mode de coulée a permis une considérable simplification de la gamme de fabrication (suppression du dégrossissage au blooming). La généralisation de la coulée continue aux aciers inoxydables fut assez tardive car il fallait satisfaire à deux impératifs qualitatifs essentiels : l’état de surface et la propreté inclusionnaire du métal déjà largement pris en compte par les affinages AOD et VOD. La complexité de la séquence de solidification des aciers inoxydables, notamment celle des aciers austénitiques, a aussi pesé sur le choix du mode de coulée. Le choix des outils de la filière coulée continue/mise en forme à chaud, pour les produits plats, est largement conditionné par le volume de production et par la proximité d’un train à bandes. Le laminoir Steckel a eu son utilité pour des productions de faibles volumes. Aujourd’hui les grandes usines en produits plats en aciers inoxydables ont des capacités suffisamment importantes pour leur dédier un train à bande (TAB) ; d’autres utilisent, en association, un train à bande pour aciers au carbone. La résolution des problèmes particuliers posés par la mise en forme à chaud des aciers inoxydables, notamment ceux liés au trou de ductilité à chaud des austénites, est décrite. Les cas particuliers de la mise en forme à chaud des tubes, des produits forgés sont évoqués. Les questions concernant la mise en forme à froid : laminage, emboutissage, écrouissage… sont abordées.

Modelling the Air-Cooled Gas Turbine: Part 1 — General Thermodynamics

2001 ◽  
Author(s):  
J. B. Young ◽  
R. C. Wilcock
Keyword(s):  
Gas Turbine ◽  
Performance Prediction ◽  
Real Gas ◽  
Thermal Mixing ◽  
Ideal Gases ◽  
Formal Framework ◽  
Considerable Simplification ◽  
Cycle Efficiency ◽  
General Thermodynamics

This paper is Part I of a study concerned with developing a formal framework for modelling air-cooled gas turbine cycles and deals with basic thermodynamic issues. Such cycles involve gas mixtures with varying composition which must be modelled realistically. A possible approach is to define just two components, air and gas, the latter being the products of stoichiometric combustion of the fuel with air. If these components can be represented as ideal gases, the entropy increase due to compositional mixing, although a true exergy loss, can be ignored for the purpose of performance prediction. This provides considerable simplification. Consideration of three idealised simple cycles shows that the introduction of cooling with an associated thermal mixing loss does not necessarily result in a loss of cycle efficiency. This is no longer true when real gas properties and turbomachinery losses are included. The analysis clarifies the role of the cooling losses and shows the importance of assessing performance in the context of the complete cycle. There is a strong case for representing the cooling losses in terms of irreversible entropy production as this provides a formalised framework, clarifies the modelling difficulties and aids physical interpretation. Results are presented which show the effects on performance of varying cooling flowrates and cooling losses. A comparison between simple and reheat cycles highlights the rôle of the thermal mixing loss. Detailed modelling of the heat transfer and cooling losses is discussed in Part II of this paper.

scholarly journals A facilely synthesized ‘spiro’ hole-transporting material based on spiro[3.3]heptane-2,6-dispirofluorene for efficient planar perovskite solar cells

RSC Advances ◽  
2017 ◽  
Vol 7 (66) ◽  
pp. 41903-41908 ◽  
Author(s):  
Zhanfeng Li ◽  
Jinbo Chen ◽  
Hui Li ◽  
Qi Zhang ◽  
Zhiliang Chen ◽  
...  
Keyword(s):  
Solar Cells ◽  
Low Cost ◽  
Perovskite Solar Cells ◽  
Considerable Simplification ◽  
Hole Transporting ◽  
Hole Transporting Material

A low-cost spiro[3.3]heptane-2,6-dispirofluorene-based HTM termed SDF-OMeTAD has been designed and synthesized via a two-step reaction, representing a considerable simplification with respect to that of the well-known spiro-OMeTAD.

scholarly journals A new derivation of the quadratic equation for the masses of the proton and electron

1940 ◽  
Vol 174 (956) ◽  
pp. 16-41 ◽  
Keyword(s):  
Relativistic Theory ◽  
Quadratic Equation ◽  
Relativity Theory ◽  
Physical Problems ◽  
Considerable Simplification ◽  
Physical Insight ◽  
The Masses

1. In this paper I introduce some improvements of method which will, I think, bring about a considerable simplification of most of the physical problems treated in Part II of my book, Relativity theory of protons and electrons (hereinafter referred to as P. and E. ). They also facilitate the extension of the theory to other problems awaiting solution. Here I confine myself to one of the problems, namely, the derivation of the fundamental quadratic 10 m 2 - 136 mm 0 + m 2 0 = 0 for the mass m of a proton or electron. The derivation in P. and E. is, I believe, valid, though it now appears clumsy. But a proof giving more physical insight was greatly to be desired, since a thorough understanding of the underlying meaning of this relation is the first condition for a general advance. A general acquaintance with the relativistic theory in P. and E. must be presumed; but, as it happens, there is little occasion to refer to the more specialized parts of the theory.

On the Heaving Motion of Cylinders of Shallow Draft

1961 ◽  
Vol 5 (04) ◽  
pp. 34-43
Author(s):  
R. C. MacCamy
Keyword(s):  
Integral Equations ◽  
Circular Disk ◽  
Finite Width ◽  
Two Dimensional ◽  
Virtual Mass ◽  
Method Of Integral Equations ◽  
First Approximation ◽  
Strip Theory ◽  
Considerable Simplification ◽  
Special Case

A perturbation procedure is developed for the two-dimensional motion produced by a long ship in heave when the draft is assumed small. The procedure reduces the shallow draft problem to a series of problems for a "raft" of zero draft. A considerable simplification in the method of integral equations is found to occur. For the first approximation, that is, a raft of finite width, the integral equations are solved numerically to determine pressure, virtual mass and damping. The problem of heave of a circular disk of zero draft is treated by the same methods so that an evaluation of strip theory in this special case is possible.

Vibration of Beams Carrying Discrete Dampers and Masses

1979 ◽  
Vol 101 (2) ◽  
pp. 317-321 ◽  
Author(s):  
M. A. Satter
Keyword(s):  
Fourier Transform ◽  
Numerical Calculations ◽  
Damping Coefficient ◽  
Transform Method ◽  
Fourier Transform Method ◽  
Simply Supported Beam ◽  
Simply Supported ◽  
Damping Coefficients ◽  
Considerable Simplification

Vibration of beams carrying discrete dampers and masses has been studied using standard Fourier transform method. It has been shown that the discrete damping coefficients can be expressed as a function of a uniformly distributed damping coefficient and this leads to a considerable simplification of the mathematics involved. A simply supported and a clamped beam have been considered, but emphasis for numerical calculations has been given on the simply supported beam. The calculations have been verified experimentally.

Dimensional reduction and background field quantization

1982 ◽  
Vol 60 (10) ◽  
pp. 1429-1430
Author(s):  
Gerry McKeon
Keyword(s):  
Dimensional Reduction ◽  
Background Field ◽  
Matrix Elements ◽  
S Matrix ◽  
Considerable Simplification ◽  
Field Quantization

It is pointed out that if one uses dimensional reduction to regularize integrals that arise when one evaluates S-matrix elements defined by background field quantization, a considerable simplification occurs.

ON THE THEORY OF FLOW OF UNDERGROUND FLUIDS IN COMPRESSIBLE STRATA

1959 ◽  
Vol 37 (3) ◽  
pp. 276-284
Author(s):  
A. E. Scheidegger
Keyword(s):  
Porous Medium ◽  
Vertical Direction ◽  
Complex Problem ◽  
Flow Equation ◽  
Local Anisotropy ◽  
Local Isotropy ◽  
Differential Flow ◽  
Considerable Simplification ◽  
General Geometry ◽  
Made In

The problem of flow of a fluid within a compressible porous medium is investigated. It is shown that in general, the motion of the fluid cannot be separated from that of the medium. This leads to a very complex problem of consolidation. However, considerable simplification can be made in applications to the flow of underground fluids. In that case, the general geometry of the consolidation can be predicted since the latter can take place in the vertical direction only. Furthermore, in many cases it is possible to neglect the volume compressibility of the porous matrix.Two cases have been considered: that of local isotropy of stress and permeability and that of local anisotropy of these two quantities. The basic differential flow equation for the two cases is deduced.

scholarly journals Simplifying the one-loop five graviton amplitude in type IIB string theory

2017 ◽  
Vol 32 (14) ◽  
pp. 1750074 ◽  
Author(s):  
Anirban Basu
Keyword(s):  
Green Function ◽  
String Theory ◽  
Fundamental Domain ◽  
Green Functions ◽  
Considerable Simplification ◽  
The Green Function ◽  
Type Iib String Theory ◽  
The One

We consider the [Formula: see text] and [Formula: see text] terms in the low momentum expansion of the five graviton amplitude in type IIB string theory at one loop. They involve integrals of various modular graph functions over the fundamental domain of [Formula: see text]. Unlike the graphs which arise in the four graviton amplitude or at lower orders in the momentum expansion of the five graviton amplitude where the links are given by scalar Green functions, there are several graphs for the [Formula: see text] and [Formula: see text] terms where each of these two links are given by a derivative of the Green function. Starting with appropriate auxiliary diagrams, we show that these graphs can be expressed in terms of those which do not involve any derivatives. This results in considerable simplification of the amplitude.

Astronomical Refraction at Low Altitudes in Marine Navigation

1952 ◽  
Vol 5 (4) ◽  
pp. 307-330 ◽  
Author(s):  
A. Fletcher
Keyword(s):  
Lower Stratosphere ◽  
Great Majority ◽  
Mathematical Function ◽  
Intrinsic Variability ◽  
Atmospheric Refraction ◽  
Large Numbers ◽  
Considerable Simplification ◽  
Low Altitude ◽  
Astronomical Refraction ◽  
Marine Navigation

Every navigator is familiar with the necessity for correcting sextant observations of altitude for the effect of atmospheric refraction. He does this by means of tables which the great majority of navigators are compelled to take on trust, as they would a table of haversines. Unfortunately it is much easier to guarantee the accuracy of a table of a straightforward mathematical function than it is to tabulate accurately an optical effect occurring in a notoriously variable atmosphere. Recent American work based on large numbers of marine observations has to some extent called into question the accuracy of the low-altitude portions of the usual tables, and it therefore seems worth while to give a brief account of refraction theory and also to consider how far it is confirmed by observation. The treatment will be restricted to refraction as it affects marine navigation. This is a considerable simplification. Aerial observations may be made at any level between the ground and the lower stratosphere, so that air navigation involves a much greater range of pressures and temperatures at the position of the observer. Moreover, it involves some occurrence of much more strongly negative altitudes than can be observed from bridge height on a ship, and at such negative altitudes (i.e. zenith distances over 90°) the intrinsic variability of the refraction is large enough to make any table rather unreliable.

scholarly journals Quintom cosmological model and some possible solutions using Lie and Noether symmetries

2016 ◽  
Vol 25 (14) ◽  
pp. 1650110 ◽  
Author(s):  
Sourav Dutta ◽  
Muthusamy Lakshmanan ◽  
Subenoy Chakraborty
Keyword(s):  
Lie Algebra ◽  
Physical System ◽  
Three Dimensional ◽  
Noether Symmetry ◽  
Conserved Quantities ◽  
Considerable Simplification ◽  
Present Context ◽  
Augmented Space ◽  
Constants Of Motion ◽  
Flrw Universe

The present work deals with a quintom model of dark energy in the framework of a spatially flat isotropic and homogeneous Friedmann–Lemaitre–Robertson–Walker (FLRW) universe. At first, Lie point symmetry is imposed to the system and the unknown coupled potential of the model is determined. Then Noether symmetry, which is also a point like symmetry of the Lagrangian, is imposed on the physical system and the potential takes a general form. It is shown that the Lie algebra of Noether symmetry is a sub-algebra of the corresponding Lie algebra of the Lie symmetry. Finally, a point transformation in the three-dimensional augmented space is performed suitably so that one of the variables become cyclic and as a result there is considerable simplification to the physical system. Hence, conserved quantities (i.e. constants of motion) are expressed in a compact form and cosmological solutions are evaluated and analyzed in the present context.

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