Papers by Abdelouahed Hamdi
Current Pediatric Research, 2009
Recent surveys have shown that asthma management is still not optimal. The aim of this study was ... more Recent surveys have shown that asthma management is still not optimal. The aim of this study was to determine the degree of utilization of the corticosteroids and others antiasthmatic medications in asthmatic children who were treated in the emergency room (ER). The study-sample ...
Communications in Statistics, Jun 5, 2023
Mathematics, Aug 8, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Journal of Inequalities and Applications, Oct 13, 2014
Dedicated to Professor Shih-Sen Chang on the occasion of his 80th birthday.
Applied Mathematics E-Notes [electronic only], 2006
We introduce a family of new transforms based on the imitation of the Bregman proximal mapping to... more We introduce a family of new transforms based on the imitation of the Bregman proximal mapping to minimize the difference of two convex functions. It can be seen as a descent scheme which takes into consideration the convex properties of the two convex functions separately. A direct application of the proposed scheme to variational inclusion is given.
Communications in Statistics, Jan 29, 2021
In this paper, we introduce a new concept of preinvex functions which is called general h-harmoni... more In this paper, we introduce a new concept of preinvex functions which is called general h-harmonic preinvex for real-valued stochastic processes. Further, we define the multidimensional general h-h...
Journal of Inequalities and Applications, Mar 23, 2023
Integral inequalities with generalized convexity play an important role in both applied and theor... more Integral inequalities with generalized convexity play an important role in both applied and theoretical mathematics. The theory of integral inequalities is currently one of the most rapidly developing areas of mathematics due to its wide range of applications. In this paper, we study the concept of higher-order strongly exponentially convex functions and establish a new Hermite-Hadamard inequality for the class of strongly exponentially convex functions of higher order. Further, we derive some new integral inequalities for Riemann-Liouville fractional integrals via higher-order strongly exponentially convex functions. These findings include several well-known results and newly obtained results as special cases. We believe that the results presented in this paper are novel and will be beneficial in encouraging future research in this field.
Mathematical and Computer Modelling, Jul 1, 2001
ABSTRACT For a quorum queueing system, the system size steady-state initial probability vector is... more ABSTRACT For a quorum queueing system, the system size steady-state initial probability vector is usually found by solving a simple system of linear equations, but computation of the system size steady-state tail probability vector requires the inversion of the probability generating function. We use in this paper the initial probability vector to compute the mean system size and then, using the mean system size, we compute the maximum entropy approximation of the tail probability vector, thus avoiding inversion of the probability generating function. In a numerical example, comparison of the initial probability vectors obtained by the exact and approximate methods proved to be excellent. We also show how to compute the tail probability vector.
Journal of Intelligent & Fuzzy Systems, 2019
In this paper, we have used a novel initialization strategy to improve Whale optimization algorit... more In this paper, we have used a novel initialization strategy to improve Whale optimization algorithm (WOA) which is named as The Improved Whale Optimization Algorithm (IWOA). To evaluate the capability of the algorithm in terms of efficiency and performance we have implemented it to solve thermal economic multi-objective optimization problems of Plate Fin Heat Exchanger (PFHE). We have investigated the design problem with a single-objective as well as multi-objectives. In single-objective we have minimized the total cost and maximized the effectiveness of PFHE. In multi-objective, we have combined the total cost and effectiveness, with the help of design weights and a penalty parameter. The sensitivity of IWOA is checked towards the change in population sizes and the target prey numbers. The algorithm was stable in calculating the best values, but was variative in number of functions evaluations. The performance of IWOA is compared with Genetic Algorithm (GA), Elitist-Jaya Algorithm (EJA), and modified-TLBO (Teaching Learning Based Optimization). Which show that IWOA has significantly improved the results. The suggested algorithm has less parameters to be set by designers. It converges to the required results quickly and is easy to implement. Similarly, all the experiments suggested that IWOA is applicable to design problems with complex objectives and highly non-linear constraints.
Discrete Mathematics, Algorithms and Applications
In this paper, we study mean–variance–Conditional Value-at-Risk (CVaR) portfolio optimization pro... more In this paper, we study mean–variance–Conditional Value-at-Risk (CVaR) portfolio optimization problem with short selling, cardinality constraint and transaction costs. To tackle its mixed-integer quadratic optimization model for large number of scenarios, we take advantage of the penalty decomposition method (PDM). It needs solving a quadratic optimization problem and a mixed-integer linear program at each iteration, where the later one has explicit optimal solution. The convergence of PDM to a partial minimum of original problem is proved. Finally, numerical experiments using the S&P index for 2020 are conducted to evaluate efficiency of the proposed algorithm in terms of return, variance and CVaR gaps and CPU times.
Communications in Statistics - Theory and Methods
Mathematics and Computers in Simulation
Statistics, Optimization & Information Computing
In this paper, we study the cardinality constrained mean-absolute deviation portfolio optimizatio... more In this paper, we study the cardinality constrained mean-absolute deviation portfolio optimization problem with risk-neutral interest rate and short-selling. We enhance the model by adding extra constraints to avoid investing in those stocks without short-selling positions. Also, we further enhance the model by determining the short rebate based on the return. The penalty alternating direction method is used to solve the mixed integer linear model. Finally, numerical experiments are provided to compare all models in terms of Sharpe ratios and CPU times using the data set of the NASDAQ and S&P indexes.
Journal of Optimization Theory and Applications, 2022
In this paper, we study the minimization of an indefinite quadratic function over the intersectio... more In this paper, we study the minimization of an indefinite quadratic function over the intersection of balls and linear inequality constraints (QOBL). Using the hyperplanes induced by the intersection of each pair of balls, we show that the optimal solution of QOBL can be found by solving several extended trust-region subproblems (e-TRS). To solve e-TRS, we use the alternating direction method of multipliers approach and a branch and bound algorithm. Numerical experiments show the efficiency of the proposed approach compared to the CVX and the extended adaptive ellipsoid-based algorithm.
April 2020
In modern and large scale power distribution topologies, directional relays play an important rol... more In modern and large scale power distribution topologies, directional relays play an important role in the operation of an electrical system. These relays must be coordinated optimally so that their overall operating time is reduced to a minimum. They are sensor protection devices for the power systems and must be coordinated properly. The present work uses a metaheuristic optimization technique known as the Plant Propagation Algorithm (PPA) in order to suggest improved solutions for the optimization problem of coordination of directional overcurrent relays (DOCRs). We have obtained comparatively better solutions for the overall operating times taken by relays fitted on important positions in the system. Our findings are useful in isolating the faulty lines efficiently and in keeping the continuity of power supply. The difference in response times taken in coordination between primary relays and corresponding backup relays is minimized. The output of our experiments is compared with ...
RAIRO Oper. Res., 2021
In this paper, we study a nonconvex quadratic minimization problem with two quadratic constraints... more In this paper, we study a nonconvex quadratic minimization problem with two quadratic constraints, one of which being convex. We introduce two convex quadratic relaxations (CQRs) and discuss cases, where the problem is equivalent to exactly one of the CQRs. Particularly, we show that the global optimal solution can be recovered from an optimal solution of the CQRs. Through this equivalence, we introduce new conditions under which the problem enjoys strong Lagrangian duality, generalizing the recent condition in the literature. Finally, under the new conditions, we present necessary and sufficient conditions for global optimality of the problem.
In this paper, we present several algorithms of the projection type to solve a class of nonconvex... more In this paper, we present several algorithms of the projection type to solve a class of nonconvex variational problems.
Optimization Letters
In this paper, we study the extended trust-region subproblem in which the trust-region intersects... more In this paper, we study the extended trust-region subproblem in which the trust-region intersects the ball with m linear inequality constraints (m-eTRS). We assume that the linear constraints do not intersect inside the ball. We show that the optimal solution of m-eTRS can be found by solving one TRS, computing the local non-global minimizer of TRS if it exists and solving at most two TRSs with an additional linear equality constraint (1-eqTRS). Both TRS and (1-eqTRS) are polynomially and efficiently solvable, thus the new algorithm significantly improves over the SOCP/SDP relaxation of Burer and Yang [Math Program 149(1-2):253–264, 2015]. on two classes of test problems, the efficiency of the proposed approach is compared with the SOCP/SDP relaxation and branch and bound algorithm of Beck and Pan [J Global Optim 69(2):309–342, 2017].
Le travail effectue dans cette these est compose principalement de trois parties. La premiere par... more Le travail effectue dans cette these est compose principalement de trois parties. La premiere partie est consacree a une analyse detaillee de la litterature concernant les methodes de penalisation, les methodes lagrangiennes, les methodes de lagrangiens augmentes, les methodes proximales et leurs relations avec la dualite. Une premiere contribution de cette partie se trouve dans une extension de l'analyse de convergence de la methode des multiplicateurs avec elimination partielle des contraintes, due a d. Bertsekas, dans le cadre d'un probleme d'optimisation non necessairement convexe avec des contraintes mixtes. Notre deuxieme contribution se situe dans l'amelioration des resultats de convergence locale de l'algorithme proximal des multiplicateurs, dans le cas d'un probleme non convexe. L'amelioration consiste en l'abandon des hypotheses d'optimalite du second ordre. La deuxieme partie de la these propose une nouvelle approche de la separabilite ...
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Papers by Abdelouahed Hamdi