Doctorat (Physique)http://hdl.handle.net/123456789/1331242018-05-21T21:01:19Z2018-05-21T21:01:19ZEtude des réactions de précipitation continue et des propriétés mécaniques des alliages à base d’aluminium.Amrane, ChahiraHamana, Djamelhttp://hdl.handle.net/123456789/1363252018-05-10T14:18:57Z2018-04-24T00:00:00ZEtude des réactions de précipitation continue et des propriétés mécaniques des alliages à base d’aluminium.
Amrane, Chahira; Hamana, Djamel
The Al-Mg alloys are widely used in industry especially for marine applications since they
possess good properties such as general corrosion resistance, strength, weldability, weight
compared to other Al alloys and formability. These properties are related to the magnesium
content and to the applied heat treatments. These alloys undergo phase transitions by
precipitation which improves their mechanical properties following solution heat treatments
and suitable ageing ones. Although these alloys are already well studied, the questions
concerning the stability of the microstructure and the effect of the various heat treatments are
always asked. In this work, we present a study on the evolution of the precipitation
(continuous one) reactions after quenching, more precisely the evolution of the precipitated
phases (formation, coalescence, and dissolution), in Al-(12, 10 and 8)wt.% Mg alloys aged at
150 and 250 °C during different ageing times. The use of various experimental techniques as
differential dilatometry, differential scanning calorimetry, scanning and transmission electron
microscopy, X-ray diffraction, microhardness and internal friction measurements, shows their
importance and their complementarity in the study of ageing process in these alloys. The
obtained results clarified the parameters that govern the stage of β’and β particles appearance
and the mechanical responses to the applied heat treatments. The ageing effect of a
supersaturated solid solution on the Temperature Dependent Internal Friction (TDIF) spectra
has been studied. A detailed TDIF analysis revealed the sensibility of the internal friction
technique to the formation of semi-coherent and non-coherent phases (β' and β) but not
enough to the formation of coherent phases (GP zones). Several observations on the nature
and the shape of the precipitates are also discussed.
2018-04-24T00:00:00ZDifférents aspects de la gravitation et de la non commutativité avec quelques applications cosmologiques.Bouhallouf, HabibaMebarki, Noureddinehttp://hdl.handle.net/123456789/1363062018-04-16T09:05:48Z2017-12-21T00:00:00ZDifférents aspects de la gravitation et de la non commutativité avec quelques applications cosmologiques.
Bouhallouf, Habiba; Mebarki, Noureddine
Noncommutative geometry has a very important role in gravitation word because it answers to a lot of questions and explain several phenomena.
With the properties of noncommutative space-time (Seiberg-Witten mapping with Moyal-Weyl ordering), Chiral and gravitational anomalies can be calculated using Fujikawa method in path integral formalism. The result obtained is very important because the non-commutativity gives in this case to space-time a gravitational aspect without a gravitational force where the noncommutativity modifies its Riemannian structure to another one more complicated having a general form of the space-time metric (with torsion and no-metricity).
A contraction of a noncommutative De Sitter SO (4,1) gauge group to the Poincaré (inhomogeneous Lorentz) group ISO (3,1) leads to a deformed gauge fields using the Seiberg-Witten maps, which by explicit calculations gives a deformed metric. This metric (application to FRW space-time) shows several properties of the corresponding black hole. (Calculations and graphs are realized by Maple).
The instability against emission of fermionic particles by the trapping horizon of an evolving black hole is analyzes using the Hamilton-Jacobi method via tunneling effect. This study leads to calculate noncommutative Hawking temperature defined by the surface gravity; this result is purely noncommutative and justified by the graphs showing the variation of Hawking temperature with event horizon and the parameter of noncommutativity.
Finally, Hamilton-Jacobi method via is always useful to study black hole’s radiation via tunneling effect near apparent horizon of Lyra black holes. The correction spending Hawking temperature depends only of the black hole properties (mass) and the structure of Lyra space-time.
2017-12-21T00:00:00ZÉtude de l’effet monopolaire sur les noyaux impair-impairs dans la région de l’étain 132.Laouet, NadjetBenrachi, Fatimahttp://hdl.handle.net/123456789/1362802018-04-16T09:02:55Z2017-09-07T00:00:00ZÉtude de l’effet monopolaire sur les noyaux impair-impairs dans la région de l’étain 132.
Laouet, Nadjet; Benrachi, Fatima
The monopole interaction, which result from the interaction between the magic core and the
valence particles, has a particular interest in the study of nuclear structure and in the
comprehension of the appearance of new magic numbers.
In this thesis, the study is founded on the calculation of the excitation energies and the
electromagnetic properties of odd-odd nuclei with few hole or few particles in addition to the
132Sn core: 128Ag, 130In, 132-134-136-138Sb, 134-136I and 136-138Cs.
Basing on the interactions jj45apn, sn100pn and kh5082 with the model spaces jj45pn, jj55pn
and jj56pn, we have realised some modifications considering the monopole interaction. New
interactions named jj45pnh, snh, cdbm and mkh are then elaborated. The recent values of single
particle and single hole energies are used. The calculations are realised in the frame work of the
nuclear shell model by means of Oxbash nuclear structure code.
The effective charges ep=1.35e and en=0.9e, leading to reproduce the experimental values of
the electromagnetic reduced transition probabilities B(M1) and B(E2) and the moments Q and
µ are used in the calculations.
The getting results are in agreement with the experimental data and better than other calculation
results.
2017-09-07T00:00:00ZEtude phénoménologique du secteur des interactions électrofaibles dans les théories au-delà du Modèle Standard.Chadou, IlhemMebarki, Noureddinehttp://hdl.handle.net/123456789/1362782018-04-16T09:02:24Z2018-02-08T00:00:00ZEtude phénoménologique du secteur des interactions électrofaibles dans les théories au-delà du Modèle Standard.
Chadou, Ilhem; Mebarki, Noureddine
In this thesis, we have studied the phenomenological study of theories
beyond the standard model, and in particular the non-commutative
standard model, in the electroweak interaction sector.
For thus studied, we have many processes of particle physics:
Production and disintegration of the Higgs boson, production of direct
photons following the proton-antiproton annihilation, electronpositron annihilation in two photons. This essentially allowed us to
analyze the behavior of the non-commutative cross section and to
deduce new bonds on the non-commutativity parameter.
2018-02-08T00:00:00Z