In this paper, a two-dimensional nonlinear coupled Gray Scott system is simulated with a finite difference scheme and a finite volume technique. Pre and post-processing lead to a new solution called GSmFoam by underst...In this paper, a two-dimensional nonlinear coupled Gray Scott system is simulated with a finite difference scheme and a finite volume technique. Pre and post-processing lead to a new solution called GSmFoam by understandin<span>g geometry settings and mesh information. The concentration profile chan</span>ges over time, as does the intensity of the contour patterns. The OpenFoam solver gives you the confidence to compare the pattern result with efficient numerical algorithms on the Gray Scott model.展开更多
This research paper represents a numerical approximation to three interesting equations of Fisher, which are linear, non-linear and coupled linear one dimensional reaction diffusion equations from population genetics....This research paper represents a numerical approximation to three interesting equations of Fisher, which are linear, non-linear and coupled linear one dimensional reaction diffusion equations from population genetics. We studied accuracy in term of L∞ error norm by random selected grids along time levels for comparison with exact results. The test example demonstrates the accuracy, efficiency and versatility of the proposed schemes. It is shown that the numerical schemes give better solutions. Moreover, the schemes can be easily applied to a wide class of higher dimension non-linear reaction diffusion equations.展开更多
In this paper, we originate results with finite difference schemes to approximate the solution of the classical Fisher Kolmogorov Petrovsky Piscounov (KPP) equation from population dynamics. Fisher’s equation describ...In this paper, we originate results with finite difference schemes to approximate the solution of the classical Fisher Kolmogorov Petrovsky Piscounov (KPP) equation from population dynamics. Fisher’s equation describes a balance between linear diffusion and nonlinear reaction. Numerical example illustrates the efficiency of the proposed schemes, also the Neumann stability analysis reveals that our schemes are indeed stable under certain choices of the model and numerical parameters. Numerical comparisons with analytical solution are also discussed. Numerical results show that Crank Nicolson and Richardson extrapolation are very efficient and reliably numerical schemes for solving one dimension fisher’s KPP equation.展开更多
This paper introduces a unified operator theory approach to the abstract Fourier analysis over homogeneous spaces of compact groups. Let G be a compact group and H be a closed subgroup of G. Let G/H be the left coset ...This paper introduces a unified operator theory approach to the abstract Fourier analysis over homogeneous spaces of compact groups. Let G be a compact group and H be a closed subgroup of G. Let G/H be the left coset space of H in G and μ be the normalized G-invariant measure on G/H associated to the Weil＇s formula. Then, we present a generalized abstract framework of Fourier analysis for the Hilbert function space L^2 （G / H, μ）.展开更多
This research paper represents a numerical approximation to non-linear coupled one dimension reaction diffusion system, which includes the existence and uniqueness of the time dependent solution with upper and lower b...This research paper represents a numerical approximation to non-linear coupled one dimension reaction diffusion system, which includes the existence and uniqueness of the time dependent solution with upper and lower bounds of the solution. Also numerical approximation is obtained by finite difference schemes to reach at reasonable level of accuracy, which is magnified by L2, L∞ and relative error norms. The accuracy of the approximations is shown by randomly selected grid points along time level and comparison with analytical results. The test example demonstrates the accuracy, efficiency and versatility of the proposed schemes. Moreover, the schemes can be easily applied to a wide class of higher dimension non-linear reaction diffusion equations with a little modifications.展开更多
In this paper, we focus on the theoretical and numerical aspects of network problems. For an illustration, we consider the urban traffic problems. And our effort is concentrated on the numerical questions to locate th...In this paper, we focus on the theoretical and numerical aspects of network problems. For an illustration, we consider the urban traffic problems. And our effort is concentrated on the numerical questions to locate the optimal network in a given domain (for example a town). Mainly, our aim is to find the network so as the distance between the population position and the network is minimized. Another problem that we are interested is to give an numerical approach of the Monge and Kantorovitch problems. In the literature, many formulations (see for example [1-4]) have not yet practical applications which deal with the permutation of points. Let us mention interesting numerical works due to E. Oudet begun since at least in 2002. He used genetic algorithms to identify optimal network (see [5]). In this paper we introduce a new reformulation of the problem by introducing permutations . And some examples, based on realistic scenarios, are solved.展开更多
Decision-making based on artificial intelligence(AI)methodology is increasingly present in all areas of modern medicine.In recent years,models based on deep-learning have begun to be used in organ transplantation.Taki...Decision-making based on artificial intelligence(AI)methodology is increasingly present in all areas of modern medicine.In recent years,models based on deep-learning have begun to be used in organ transplantation.Taking into account the huge number of factors and variables involved in donor-recipient(DR)matching,AI models may be well suited to improve organ allocation.AI-based models should provide two solutions:complement decision-making with current metrics based on logistic regression and improve their predictability.Hundreds of classifiers could be used to address this problem.However,not all of them are really useful for D-R pairing.Basically,in the decision to assign a given donor to a candidate in waiting list,a multitude of variables are handled,including donor,recipient,logistic and perioperative variables.Of these last two,some of them can be inferred indirectly from the team’s previous experience.Two groups of AI models have been used in the D-R matching:artificial neural networks(ANN)and random forest(RF).The former mimics the functional architecture of neurons,with input layers and output layers.The algorithms can be uni-or multi-objective.In general,ANNs can be used with large databases,where their generalizability is improved.However,they are models that are very sensitive to the quality of the databases and,in essence,they are black-box models in which all variables are important.Unfortunately,these models do not allow to know safely the weight of each variable.On the other hand,RF builds decision trees and works well with small cohorts.In addition,they can select top variables as with logistic regression.However,they are not useful with large databases,due to the extreme number of decision trees that they would generate,making them impractical.Both ANN and RF allow a successful donor allocation in over 80%of D-R pairing,a number much higher than that obtained with the best statistical metrics such as model for end-stage liver disease,balance of risk score,and survival outcomes following liver transplantation scores.Many barriers need to be overcome before these deeplearning-based models can be included for D-R matching.The main one of them is the resistance of the clinicians to leave their own decision to autonomous computational models.展开更多
This paper presents a short contribution in air transportation, specifically in scheduling aircraft (plane) landings at Léopol Sédar Senghor (LSS) airport of Dakar. The safety of air navigation of LSS is man...This paper presents a short contribution in air transportation, specifically in scheduling aircraft (plane) landings at Léopol Sédar Senghor (LSS) airport of Dakar. The safety of air navigation of LSS is managed by ASECNA: Agency for Air Navigation Safety in Africa and Madagascar. Scheduling aircraft landing is the problem of deciding a landing time on an appropriate runway for each aircraft in a given set of aircraft such that each aircraft lands within a predetermined time window. The separation criteria between the landing of an aircraft, and the landing of all successive aircraft, are respected. Our objective is to minimize the cost of deviation from the target times. We present a mixed-integer 0 - 1 formulation for the single runway case. Numerical experiments and comparisons based on real datasets of LSS airport are presented.展开更多
In this research article, two finite difference implicit numerical schemes are described to approximate the numerical solution of the two-dimension modified reaction diffusion Fisher’s system which exists in coupled ...In this research article, two finite difference implicit numerical schemes are described to approximate the numerical solution of the two-dimension modified reaction diffusion Fisher’s system which exists in coupled form. Finite difference implicit schemes show unconditionally stable and second-order accurate nature of computational algorithm also the validation and comparison of analytical solution, are done through the examples having known analytical solution. It is found that the numerical schemes are in excellent agreement with the analytical solution. We found, second-implicit scheme is much faster than the first with good rate of convergence also we used NVIDA devices to accelerate the computations and efficiency of the algorithm. Numerical results show our proposed schemes with use of HPC (High performance computing) are very efficient and reliable.展开更多
This paper focus on solving the problem of optimizing students’ orientation. After four years spent in secondary school, pupils take exams and are assigned to the high school. The main difficulty of Education Departm...This paper focus on solving the problem of optimizing students’ orientation. After four years spent in secondary school, pupils take exams and are assigned to the high school. The main difficulty of Education Department Inspection (EDI) of Dakar lies in the allocation of pupils in the suburbs. In this paper we propose an allocation model using the p-median problem. The model takes into account the distance of the standards imposed by international organizations between pupil’s home and school. The p-median problem is a location-allocation problem that takes into account the average (total) distance between demand points (pupil’s home) and facility (pupil’s school). The p-median problem is used to determine the best location to place a limited number of schools. The model has been enhanced and applied to a wide range of school location problems in suburbs. After collecting necessary numerical data to each EDI, a formulation is presented and computational results are carried out.展开更多
The nonconforming Wilson’s brick classically is restricted to regular hexahedral meshes. Lesaint and Zlamal[6] relaxed this constraint for the two-dimensional analonue of this element In this paper we extend their re...The nonconforming Wilson’s brick classically is restricted to regular hexahedral meshes. Lesaint and Zlamal[6] relaxed this constraint for the two-dimensional analonue of this element In this paper we extend their results to three dimensions and prove that and where u is the exact solution, u_h is the approximate solution and is the usual norm for the Sobolev space H^1(?).展开更多
The main purpose of this work is to show that the gravity term of the segregation-mixing equation of fine mono-disperse particles in a fluid can be derived from first-principles （i.e., elementary physics）. Our deriv...The main purpose of this work is to show that the gravity term of the segregation-mixing equation of fine mono-disperse particles in a fluid can be derived from first-principles （i.e., elementary physics）. Our derivation of the gravity-driven flux of particles leads to the simplest case of the Richardson and Zaki correlation. Stokes velocity also naturally appears from the physical parameters of the particles and fluid by means of derivation only. This derivation from first-principle physics has never been presented before. It is applicable in small concentrations of fine particles.展开更多
Many problems with underlying variational structure involve a coupling of volume with surface effects.A straight-forward approach in a finite element discretiza- tion is to make use of the surface triangulation that i...Many problems with underlying variational structure involve a coupling of volume with surface effects.A straight-forward approach in a finite element discretiza- tion is to make use of the surface triangulation that is naturally induced by the volume triangulation.In an adaptive method one wants to facilitate'matching'local mesh modifications,i.e.,local refinement and/or coarsening,of volume and surface mesh with standard tools such that the surface grid is always induced by the volume grid. We describe the concepts behind this approach for bisectional refinement and describe new tools incorporated in the finite element toolbox ALBERTA.We also present several important applications of the mesh coupling.展开更多
This research paper represents a numerical approximation to non-linear two-dimensional reaction diffusion equation from population genetics. Since various initial and boundary value problems exist in two-dimensional r...This research paper represents a numerical approximation to non-linear two-dimensional reaction diffusion equation from population genetics. Since various initial and boundary value problems exist in two-dimensional reaction-diffusion, phenomena are studied numerically by different numerical methods, here we use finite difference schemes to approximate the solution. Accuracy is studied in term of L2, L∞ and relative error norms by random selected grids along time levels for comparison with exact results. The test example demonstrates the accuracy, efficiency and versatility of the proposed schemes. It is shown that the numerical schemes give better solutions. Moreover, the schemes can be easily applied to a wide class of higher dimension nonlinear reaction diffusion equations with a little modification.展开更多
To develop an efficient numerical scheme for two-dimensional convection diffusion equation using Crank-Nicholson and ADI, time-dependent nonlinear system is discussed. These schemes are of second order accurate in apa...To develop an efficient numerical scheme for two-dimensional convection diffusion equation using Crank-Nicholson and ADI, time-dependent nonlinear system is discussed. These schemes are of second order accurate in apace and time solved at each time level. The procedure was combined with Iterative methods to solve non-linear systems. Efficiency and accuracy are studied in term of L2, L∞ norms confirmed by numerical results by choosing two test examples. Numerical results show that proposed alternating direction implicit scheme was very efficient and reliable for solving two dimensional nonlinear convection diffusion equation. The proposed methods can be implemented for solving non-linear problems arising in engineering and physics.展开更多
In this paper, we use the Adomian decomposition method (ADM), the finite differences method and the Alternating Direction Implicit method to estimate the advantages and the weakness of the above methods. For it, we ma...In this paper, we use the Adomian decomposition method (ADM), the finite differences method and the Alternating Direction Implicit method to estimate the advantages and the weakness of the above methods. For it, we make a numerical simulation of the different solutions constructed with these methods and compare the error investigated case.展开更多
This paper studies the problem of locating breakdown mechanic. We consider a public transport network in which it can provide buses failure. The objective is, taking into account the statistics of breakdowns registere...This paper studies the problem of locating breakdown mechanic. We consider a public transport network in which it can provide buses failure. The objective is, taking into account the statistics of breakdowns registered on the network, to locate optimally breakdown mechanics so as to minimize the response time (to ensure the network coverage of break- down mechanics). In this work, we present a binary linear programming model for this location problem which provides assignments-locations of areas served. Once the location made, we discuss dynamic assignment of breakdown mechan- ics depending on their position in the network at a given time t. Numerical simulation results are presented based on real data of urban transportation society of Dakar Dem Dikk.展开更多
Genital peritonitis is rare in daily surgical practice in Congo-Brazzaville. Clandestine abortions are incriminated. The purpose of the study is to analyze the epidemiological, etiological, diagnostic and therapeutic ...Genital peritonitis is rare in daily surgical practice in Congo-Brazzaville. Clandestine abortions are incriminated. The purpose of the study is to analyze the epidemiological, etiological, diagnostic and therapeutic aspects of genital peritonitis. A retrospective and case series study was realized in departments of Digestive Surgery and Gynecology-Obstetrics of the University Hospital of Brazzaville. The inclusion criteria for the diagnosis of peritonitis were abdominal pain, fever, transit disturbances and signs of peritoneal irritation. The parameters studied were: age, etiological circumstances, anatomical lesions, type of surgical treatment and evolution. During the study period (July 1, 2015-December 31, 2017), 306 patients were admitted to both departments for acute generalized peritonitis. Among them, a genital cause was incriminated in 18 (5.9%) patients. The mean age was 27.6 ± 3.1 years. At the parity and gestational level, 93% of patients had at least two pregnancies, but not more than the second trimester. In addition, 50% of the patients had an induced miscarriage, due to uterine and intestinal lesions. Induced miscarriages accounted for half of etiological circumstances. Physical examination of the abdomen revealed abdominal contracture in 61.1% of cases. Main visceral lesions were uterine perforation (55.5%) followed by rupture of tubo-ovarian abscess (38.9%). The operative follow-up was simple in 83.33% of cases. In conclusion, genital peritonitis remains unfrequented. Median laparotomy has been the main therapeutic approach in our context where emergency laparoscopic surgery is not yet common.展开更多
This paper studies the buses assignment from their depots to their routes starting points in urban transportation network. It describes a computational study to solve the dead mileage minimization to optimality. The o...This paper studies the buses assignment from their depots to their routes starting points in urban transportation network. It describes a computational study to solve the dead mileage minimization to optimality. The objective of this work is to assign the buses to depots while optimizing dead mileage associated with pull-out trips and pull-in trips. To do so, a new mixed-integer programming model with 0 - 1 variables is proposed which takes into account the specificity of the buses of Dakar Dem Dikk (the main public transportation company in Dakar). This company manages a fleet of buses which, depending on road conditions some buses cannot circulate on some roads of the network. Thus, buses are classified into two categories and are assigned based on these categories. The related mixed-integer 0 - 1 linear program is solved efficiently to minimize the cumulative distance covered by all buses. Numerical simulations on real datasets are presented.展开更多
文摘In this paper, a two-dimensional nonlinear coupled Gray Scott system is simulated with a finite difference scheme and a finite volume technique. Pre and post-processing lead to a new solution called GSmFoam by understandin<span>g geometry settings and mesh information. The concentration profile chan</span>ges over time, as does the intensity of the contour patterns. The OpenFoam solver gives you the confidence to compare the pattern result with efficient numerical algorithms on the Gray Scott model.
文摘This research paper represents a numerical approximation to three interesting equations of Fisher, which are linear, non-linear and coupled linear one dimensional reaction diffusion equations from population genetics. We studied accuracy in term of L∞ error norm by random selected grids along time levels for comparison with exact results. The test example demonstrates the accuracy, efficiency and versatility of the proposed schemes. It is shown that the numerical schemes give better solutions. Moreover, the schemes can be easily applied to a wide class of higher dimension non-linear reaction diffusion equations.
文摘In this paper, we originate results with finite difference schemes to approximate the solution of the classical Fisher Kolmogorov Petrovsky Piscounov (KPP) equation from population dynamics. Fisher’s equation describes a balance between linear diffusion and nonlinear reaction. Numerical example illustrates the efficiency of the proposed schemes, also the Neumann stability analysis reveals that our schemes are indeed stable under certain choices of the model and numerical parameters. Numerical comparisons with analytical solution are also discussed. Numerical results show that Crank Nicolson and Richardson extrapolation are very efficient and reliably numerical schemes for solving one dimension fisher’s KPP equation.
文摘This paper introduces a unified operator theory approach to the abstract Fourier analysis over homogeneous spaces of compact groups. Let G be a compact group and H be a closed subgroup of G. Let G/H be the left coset space of H in G and μ be the normalized G-invariant measure on G/H associated to the Weil＇s formula. Then, we present a generalized abstract framework of Fourier analysis for the Hilbert function space L^2 （G / H, μ）.
文摘This research paper represents a numerical approximation to non-linear coupled one dimension reaction diffusion system, which includes the existence and uniqueness of the time dependent solution with upper and lower bounds of the solution. Also numerical approximation is obtained by finite difference schemes to reach at reasonable level of accuracy, which is magnified by L2, L∞ and relative error norms. The accuracy of the approximations is shown by randomly selected grid points along time level and comparison with analytical results. The test example demonstrates the accuracy, efficiency and versatility of the proposed schemes. Moreover, the schemes can be easily applied to a wide class of higher dimension non-linear reaction diffusion equations with a little modifications.
文摘In this paper, we focus on the theoretical and numerical aspects of network problems. For an illustration, we consider the urban traffic problems. And our effort is concentrated on the numerical questions to locate the optimal network in a given domain (for example a town). Mainly, our aim is to find the network so as the distance between the population position and the network is minimized. Another problem that we are interested is to give an numerical approach of the Monge and Kantorovitch problems. In the literature, many formulations (see for example [1-4]) have not yet practical applications which deal with the permutation of points. Let us mention interesting numerical works due to E. Oudet begun since at least in 2002. He used genetic algorithms to identify optimal network (see [5]). In this paper we introduce a new reformulation of the problem by introducing permutations . And some examples, based on realistic scenarios, are solved.
基金supported by a grant from Mutua Madrile?a XVIII Convovatoria de ayudas a la investigación。
文摘Decision-making based on artificial intelligence(AI)methodology is increasingly present in all areas of modern medicine.In recent years,models based on deep-learning have begun to be used in organ transplantation.Taking into account the huge number of factors and variables involved in donor-recipient(DR)matching,AI models may be well suited to improve organ allocation.AI-based models should provide two solutions:complement decision-making with current metrics based on logistic regression and improve their predictability.Hundreds of classifiers could be used to address this problem.However,not all of them are really useful for D-R pairing.Basically,in the decision to assign a given donor to a candidate in waiting list,a multitude of variables are handled,including donor,recipient,logistic and perioperative variables.Of these last two,some of them can be inferred indirectly from the team’s previous experience.Two groups of AI models have been used in the D-R matching:artificial neural networks(ANN)and random forest(RF).The former mimics the functional architecture of neurons,with input layers and output layers.The algorithms can be uni-or multi-objective.In general,ANNs can be used with large databases,where their generalizability is improved.However,they are models that are very sensitive to the quality of the databases and,in essence,they are black-box models in which all variables are important.Unfortunately,these models do not allow to know safely the weight of each variable.On the other hand,RF builds decision trees and works well with small cohorts.In addition,they can select top variables as with logistic regression.However,they are not useful with large databases,due to the extreme number of decision trees that they would generate,making them impractical.Both ANN and RF allow a successful donor allocation in over 80%of D-R pairing,a number much higher than that obtained with the best statistical metrics such as model for end-stage liver disease,balance of risk score,and survival outcomes following liver transplantation scores.Many barriers need to be overcome before these deeplearning-based models can be included for D-R matching.The main one of them is the resistance of the clinicians to leave their own decision to autonomous computational models.
文摘This paper presents a short contribution in air transportation, specifically in scheduling aircraft (plane) landings at Léopol Sédar Senghor (LSS) airport of Dakar. The safety of air navigation of LSS is managed by ASECNA: Agency for Air Navigation Safety in Africa and Madagascar. Scheduling aircraft landing is the problem of deciding a landing time on an appropriate runway for each aircraft in a given set of aircraft such that each aircraft lands within a predetermined time window. The separation criteria between the landing of an aircraft, and the landing of all successive aircraft, are respected. Our objective is to minimize the cost of deviation from the target times. We present a mixed-integer 0 - 1 formulation for the single runway case. Numerical experiments and comparisons based on real datasets of LSS airport are presented.
文摘In this research article, two finite difference implicit numerical schemes are described to approximate the numerical solution of the two-dimension modified reaction diffusion Fisher’s system which exists in coupled form. Finite difference implicit schemes show unconditionally stable and second-order accurate nature of computational algorithm also the validation and comparison of analytical solution, are done through the examples having known analytical solution. It is found that the numerical schemes are in excellent agreement with the analytical solution. We found, second-implicit scheme is much faster than the first with good rate of convergence also we used NVIDA devices to accelerate the computations and efficiency of the algorithm. Numerical results show our proposed schemes with use of HPC (High performance computing) are very efficient and reliable.
文摘This paper focus on solving the problem of optimizing students’ orientation. After four years spent in secondary school, pupils take exams and are assigned to the high school. The main difficulty of Education Department Inspection (EDI) of Dakar lies in the allocation of pupils in the suburbs. In this paper we propose an allocation model using the p-median problem. The model takes into account the distance of the standards imposed by international organizations between pupil’s home and school. The p-median problem is a location-allocation problem that takes into account the average (total) distance between demand points (pupil’s home) and facility (pupil’s school). The p-median problem is used to determine the best location to place a limited number of schools. The model has been enhanced and applied to a wide range of school location problems in suburbs. After collecting necessary numerical data to each EDI, a formulation is presented and computational results are carried out.
文摘The nonconforming Wilson’s brick classically is restricted to regular hexahedral meshes. Lesaint and Zlamal[6] relaxed this constraint for the two-dimensional analonue of this element In this paper we extend their results to three dimensions and prove that and where u is the exact solution, u_h is the approximate solution and is the usual norm for the Sobolev space H^1(?).
文摘The main purpose of this work is to show that the gravity term of the segregation-mixing equation of fine mono-disperse particles in a fluid can be derived from first-principles （i.e., elementary physics）. Our derivation of the gravity-driven flux of particles leads to the simplest case of the Richardson and Zaki correlation. Stokes velocity also naturally appears from the physical parameters of the particles and fluid by means of derivation only. This derivation from first-principle physics has never been presented before. It is applicable in small concentrations of fine particles.
文摘Many problems with underlying variational structure involve a coupling of volume with surface effects.A straight-forward approach in a finite element discretiza- tion is to make use of the surface triangulation that is naturally induced by the volume triangulation.In an adaptive method one wants to facilitate'matching'local mesh modifications,i.e.,local refinement and/or coarsening,of volume and surface mesh with standard tools such that the surface grid is always induced by the volume grid. We describe the concepts behind this approach for bisectional refinement and describe new tools incorporated in the finite element toolbox ALBERTA.We also present several important applications of the mesh coupling.
文摘This research paper represents a numerical approximation to non-linear two-dimensional reaction diffusion equation from population genetics. Since various initial and boundary value problems exist in two-dimensional reaction-diffusion, phenomena are studied numerically by different numerical methods, here we use finite difference schemes to approximate the solution. Accuracy is studied in term of L2, L∞ and relative error norms by random selected grids along time levels for comparison with exact results. The test example demonstrates the accuracy, efficiency and versatility of the proposed schemes. It is shown that the numerical schemes give better solutions. Moreover, the schemes can be easily applied to a wide class of higher dimension nonlinear reaction diffusion equations with a little modification.
文摘To develop an efficient numerical scheme for two-dimensional convection diffusion equation using Crank-Nicholson and ADI, time-dependent nonlinear system is discussed. These schemes are of second order accurate in apace and time solved at each time level. The procedure was combined with Iterative methods to solve non-linear systems. Efficiency and accuracy are studied in term of L2, L∞ norms confirmed by numerical results by choosing two test examples. Numerical results show that proposed alternating direction implicit scheme was very efficient and reliable for solving two dimensional nonlinear convection diffusion equation. The proposed methods can be implemented for solving non-linear problems arising in engineering and physics.
文摘In this paper, we use the Adomian decomposition method (ADM), the finite differences method and the Alternating Direction Implicit method to estimate the advantages and the weakness of the above methods. For it, we make a numerical simulation of the different solutions constructed with these methods and compare the error investigated case.
文摘This paper studies the problem of locating breakdown mechanic. We consider a public transport network in which it can provide buses failure. The objective is, taking into account the statistics of breakdowns registered on the network, to locate optimally breakdown mechanics so as to minimize the response time (to ensure the network coverage of break- down mechanics). In this work, we present a binary linear programming model for this location problem which provides assignments-locations of areas served. Once the location made, we discuss dynamic assignment of breakdown mechan- ics depending on their position in the network at a given time t. Numerical simulation results are presented based on real data of urban transportation society of Dakar Dem Dikk.
文摘Genital peritonitis is rare in daily surgical practice in Congo-Brazzaville. Clandestine abortions are incriminated. The purpose of the study is to analyze the epidemiological, etiological, diagnostic and therapeutic aspects of genital peritonitis. A retrospective and case series study was realized in departments of Digestive Surgery and Gynecology-Obstetrics of the University Hospital of Brazzaville. The inclusion criteria for the diagnosis of peritonitis were abdominal pain, fever, transit disturbances and signs of peritoneal irritation. The parameters studied were: age, etiological circumstances, anatomical lesions, type of surgical treatment and evolution. During the study period (July 1, 2015-December 31, 2017), 306 patients were admitted to both departments for acute generalized peritonitis. Among them, a genital cause was incriminated in 18 (5.9%) patients. The mean age was 27.6 ± 3.1 years. At the parity and gestational level, 93% of patients had at least two pregnancies, but not more than the second trimester. In addition, 50% of the patients had an induced miscarriage, due to uterine and intestinal lesions. Induced miscarriages accounted for half of etiological circumstances. Physical examination of the abdomen revealed abdominal contracture in 61.1% of cases. Main visceral lesions were uterine perforation (55.5%) followed by rupture of tubo-ovarian abscess (38.9%). The operative follow-up was simple in 83.33% of cases. In conclusion, genital peritonitis remains unfrequented. Median laparotomy has been the main therapeutic approach in our context where emergency laparoscopic surgery is not yet common.
文摘This paper studies the buses assignment from their depots to their routes starting points in urban transportation network. It describes a computational study to solve the dead mileage minimization to optimality. The objective of this work is to assign the buses to depots while optimizing dead mileage associated with pull-out trips and pull-in trips. To do so, a new mixed-integer programming model with 0 - 1 variables is proposed which takes into account the specificity of the buses of Dakar Dem Dikk (the main public transportation company in Dakar). This company manages a fleet of buses which, depending on road conditions some buses cannot circulate on some roads of the network. Thus, buses are classified into two categories and are assigned based on these categories. The related mixed-integer 0 - 1 linear program is solved efficiently to minimize the cumulative distance covered by all buses. Numerical simulations on real datasets are presented.
