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ON SUBSPACE-SUPERCYCLIC SEMIGROUP
El Berrag, Mohammed,Tajmouati, Abdelaziz Korean Mathematical Society 2018 대한수학회논문집 Vol.33 No.1
A $C_0$-semigroup ${\tau}=(T_t)_{t{\geq}0}$ on a Banach space X is called subspace-supercyclic for a subspace M, if $\mathbb{C}Orb({\tau},x){\bigcap}M=\{{\lambda}T_tx\;:\;{\lambda}{\in}\mathbb{C},\;t{\geq}0\}{\bigcap}M$ is dense in M for a vector $x{\in}M$. In this paper we characterize the notion of subspace-supercyclic $C_0$-semigroup. At the same time, we also provide a subspace-supercyclicity criterion $C_0$-semigroup and offer two equivalent conditions of this criterion.
SPECTRA ORIGINATED FROM FREDHOLM THEORY AND BROWDER'S THEOREM
Amouch, Mohamed,Karmouni, Mohammed,Tajmouati, Abdelaziz Korean Mathematical Society 2018 대한수학회논문집 Vol.33 No.3
We give a new characterization of Browder's theorem through equality between the pseudo B-Weyl spectrum and the generalized Drazin spectrum. Also, we will give conditions under which pseudo B-Fredholm and pseudo B-Weyl spectrum introduced in [9] and [25] become stable under commuting Riesz perturbations.
CESÀRO-HYPERCYCLIC AND HYPERCYCLIC OPERATORS
El Berrag, Mohammed,Tajmouati, Abdelaziz Korean Mathematical Society 2019 대한수학회논문집 Vol.34 No.2
In this paper we provide a $Ces{\grave{a}}ro$-hypercyclicity criterion and offer two examples of this criterion. At the same time, we also characterize other properties of $Ces{\grave{a}}ro$-hypercyclic operators.
Lamrabet, Abdesslam,Maghnouj, Abdelmajid,Tajmouati, Jaouad,Bencheikh, Mohamed Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.10
The increasing interest that GEANT4 is gaining nowadays, because of its special capabilities, prompted us to address its reliability in neutronic calculation for the realistic and complex spallation target MEGAPIE of the Paul Scherrer Institute of Switzerland. In this paper we have specifically addressed the neutronic characterization of the active zone of this target. Three physical quantities are evaluated: neutron flux spectra and total neutron fluxes on target's z-axis, and the neutron yield as a function of the target's altitude and radius. Comparison of the obtained results with those of the MCNPX reference code and some experimental measurements have confirmed the impact of the geometrical and proton beam models on the neutron fluxes. It has also allowed to reveal the intrinsic influence of the code type. The resulting differences reach a factor of ~2 for the beam model and 4-18% for the other parameters cumulated. The analysis of the neutron yield has led us to conclude that: 1) Increasing the productivity of the MEGAPIE target cannot be achieved simply by increasing the thickness of the target, if the irradiation parameters are not modified. 2) The size of the spallation area needs to be redefined more precisely.
The Drazin inverse of the sum of two products
Safae Alaoui Chrifi,Abdelaziz Tajmouati 대한수학회 2022 대한수학회논문집 Vol.37 No.3
In this paper, for bounded linear operators $A,B,C$ satisfying $[AB,B]=[BC,B]=[AB,BC]=0$ we study the Drazin invertibility of the sum of products formed by the three operators $A,B$ and $C$. In particular, we give an explicit representation of the anti-commutator $\{A,B\}=AB+BA$. Also we give some conditions for which the sum $A+C$ is Drazin invertible.
Abdessamad Didi,Ahmed Dadouch,Otman Jaï,Jaouad Tajmouati,Hassane El Bekkouri 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.4
Americiumeberyllium (Am-Be; n, γ) is a neutron emitting source used in various research fields such as chemistry, physics, geology, archaeology, medicine, and environmental monitoring, as well as in the forensic sciences. It is a mobile source of neutron activity (20 Ci), yielding a small thermal neutron flux that is water moderated. The aim of this study is to develop a model to increase the neutron thermal flux of a source such as Am-Be. This study achieved multiple advantageous results: primarily, it will help us perform neutron activation analysis. Next, it will give us the opportunity to produce radio-elements with short half-lives. Am-Be single and multisource (5 sources) experiments were performed within an irradiation facility with a paraffin moderator. The resulting models mainly increase the thermal neutron flux compared to the traditional method with water moderator.