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Application of the p-Median Problem in School Allocation

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American Journal of Operations Research 2012年第2期2卷 253-259页

作者： Fagueye ndiaye babacar mbaye ndiaye Idrissa Ly Laboratory of Mathematics of Decision and Numerical Analysis Cheikh Anta Diop University Dakar Senegal

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.

关键词： Non-Convex Optimization Location Models School Allocation

Scheduling Aircraft Landings at LSS Airport

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American Journal of Operations Research 2012年第2期2卷 235-241页

作者： Coumba Diallo babacar mbaye ndiaye Diaraf Seck Laboratory of Mathematics of Decision and Numerical Analysis Cheikh Anta Diop University Dakar Senegal Unité Mixte Internationale UMMISCO Institut de Recherche pour le Développement Bondy France

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.

关键词： Air Traffic Control Runway Operations Scheduling Non Convex Optimization

Vitamin D Status in Healthy Children Aged 6 to 59 Months at the Pikine-Guediawaye Institute of Social Pediatrics, Dakar Suburbs (Senegal)

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Open Journal of Pediatrics 2025年第1期15卷 101-110页

作者： babacar Niang Aliou Ndongo Aminata mbaye Serigne Saliou Mbacke Ablaye ndiaye Khadidatou Diouf Abou Ba Abdallah Diallo Djibril Boiro Oulimata ndiaye Ousmane ndiaye Centre Hospitalier National dEnfants Albert Royer Dakar Senegal Centre Hospitalier Abass Ndao Dakar Senegal Laboratoire Biochimie Dakar Senegal Hpital Dalal Jam Guediawaye Senegal Institut de Pdiatrie Sociale Pikine Senegal

Introduction: Vitamin D plays a key role in phosphocalcic metabolism, in normal functioning of the immune system and in the prevention of certain forms of cancer. Systematic vitamin D supplementation has been implemented in most Western countries, which has drastically reduced the prevalence of rickets. In Senegal, a country with enough sunshine, no large-scale data exists on vitamin D deficiency in children. In addition, there are no guidelines from the Ministry of Health and Social Action (MoHSA) on vitamin D supplementation. Our objective was to determine the prevalence of vitamin D deficiency in children aged 6 to 59 months and to analyze the factors associated with it at the Institute of Social Pediatrics in Pikine-Guédiawaye, a suburb of Dakar. Patients and Methods: This was a prospective, descriptive and analytical cross-sectional study over a 3-month period (from January to March 2024) at the Institute of Social Pediatric (IPS) of Pikine-Guédiawaye. The study population consisted of all children aged 6 to 59 months free from any acute or chronic pathology, whose parents had agreed to answer the questionnaires after having consented and signed the consent and children who had had a sample taken for vitamin D dosage. Results: We included 102 children, 35 of whom had vitamin D deficiency, i.e. a prevalence of 34.31% with a slight male predominance (sex ratio 1.05). Infants aged 13 - 24 months were more affected (41.67%), but the difference was not statistically significant (p-value = 0.385). Patients with acute malnutrition had a significantly higher prevalence of vitamin D deficiency (54.17% of cases versus 28.38%) in those without acute malnutrition (p = 0.02). On the other hand, chronic malnutrition, underweight and diversification foods were not significantly associated with vitamin D deficiency (p of 0.60, 0.42 and 0.09 respectively). Conclusion: Vitamin deficiency affects one-third of apparently healthy children under 5 and this deficiency has no signific

关键词： Vitamin D Deficiency Children Supplementation

Management of Congenital Disorders in a Resource-Limited Country: Organizational Model of a Specialized Working Group within a Perinatal Network

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Open Journal of Obstetrics and Gynecology 2025年第1期15卷 10-20页

作者： Mame Diarra ndiaye Lissoune Cisse Daouda Ndour Yaye Joor Dieng Hélène Chami Mamadou Mour Traore Maguette mbaye Pape Moctar Faye Dalal Jamm National Hospital Center Dakar Senegal Cheikh Anta Diop University of Dakar Dakar Senegal Pikine National Hospital Center Dakar Senegal Albert Royer Childrens Hospital Dakar Senegal

Objective: To evaluate the organizational model of a perinatal network and its relevance in a resource-limited country. Methodology: This was a mixed prospective qualitative and quantitative study conducted over a 2-year period, from January 1, 2022, to December 31, 2023. This study took place in Senegal, a country with limited resources and a weakness of hyperspecialized medical technical resources. There was no policy for the management of fetal malformations. The qualitative part was carried out through overt participant observation. The human resources and the organization of the perinatal network were described. For the quantitative part, all fetuses managed during the study period were included. The studied parameters related to neonatal care and outcomes. Qualitative variables were described using dispersion parameters, and quantitative variables were described using proportions. Results: The perinatal network includes several specialists across six hospitals. Of these hospitals, only one provided emergency pediatric surgery. The network included highly specialized human resources in prenatal diagnosis, congenital heart defects, pediatric surgery, anesthesia, and other medical specialties in perinatology. Advanced ultrasound was centralized by an obstetrician. The team decided on the follow-up methods, timing, and mode of delivery. The newborn was immediately transferred to the appropriate specialty. Over the 2-year period, 201 fetuses were managed. The rate of cesarean delivery was 76.3%. Neonatal mortality was 51.4%. Discussion: Centralizing care improves the quality of prenatal diagnosis and management of congenital defects. Mortality remains high when emergency surgery is not well available. This mortality is also due to the lack of a single center offering all perinatal care and so, the transfer of newborns. The cesarean rate increases due to underlying conditions and organizational factors. Conclusion: Public policies should prioritize the centralizatio

关键词： Congenital Disorders Perinatal Network Resource-Limited Country Antenatal Diagnosis Care Centralization

Study of the Impact of Grid Disconnections on the Production of a Photovoltaic Solar Power Plant: Case of Diamniadio Power Plant

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Journal of Power and Energy Engineering 2023年第6期11卷 16-25页

作者： Amadou ndiaye Mohamed Cherif Aidara Amy mbaye Mamadou Lamine ndiaye Laboratoire Eau-Energie-Environnement-Procédés Industriels (L3EPI) Ecole Supérieure Polytechnique Université Cheikh Anta Diop (UCAD) Dakar Senegal

Today, renewable energy projects connected to the interconnected network, with powers of the order of tens of megawatts, are more and more numerous in sub-Saharan Africa. And financing these investments requires a reliable amortization schedule. In the context of photovoltaic systems connected to the interconnected electricity grid, the quintessence of damping is the amount of energy injected into the grid. Thus it is fundamental to know the parameters of this network and their variation. This paper presents an evaluation of the impact of power grid disturbances on the performance of a solar PV plant under real conditions. The CICAD photovoltaic solar plant, connected to the Senelec distribution network, with an installed capacity of 2 MWp is the study setting. An energy audit of the plant is carried out. Then the percentage of each loss is determined: voltage drops, module degradation, inverter efficiency. The duration of each disconnection is measured and recorded daily. The corresponding quantity of lost energy is thus calculated from meteorological data (irradiation, temperature, wind speed, illumination) recorded by the measurement unit in one-minute steps. The observation period is three months. The total duration of disconnections related to the instability of the electrical network during the study period is 46.7 hours. The amount of energy lost is estimated at 22.6 MWh. This represents 2.4% of the actual calculated production.

关键词： Photovoltaic Power Plant Disconnections Network Evaluation Lost En-ergy

Congenital Heart Disease in Rural Senegal: A Retrospective Study of 79 Patients

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Open Journal of Pediatrics 2023年第1期13卷 43-49页

作者： babacar Niang Aminata mbaye Djibril Boiro Aliou Abdoulaye Ndongo Mame Diarra Thiam Aliou Thiongane Modou Guéye Amadou Lamine Fall Ousmane ndiaye Albert Royer Children’s Hospital Dakar Sénégal Abass Ndao Hospital Dakar Sénégal

Introduction: Congenital heart disease (CHD) is a malformation of the heart present at birth and resulting from a developmental defect during embryonic life. The aim was to assess CHD in rural areas. Methodology: This is a retrospective study conducted over a period of 2 years in rural Senegal. Results: During the study period, we collected 79 patients with CHD, representing a hospital prevalence of 2.6%. The mean age at diagnosis was 17.05 months and the sex ratio was 1.19. The mean birth weight was 2826 g. The main comorbidities were anaemia (54.43%) and respiratory infections 38 cases (48.10%). Respiratory distress was the most common sign with 98.73%. Radiological cardiomegaly was noted in 86.7%. The most frequent CHD were interventricular septal defect (IVD) 21.51% and atrial septal defect (ASD) 8.86%. No patient was able to receive surgical treatment. Seven children died (8.86%) and 21 children were lost to follow-up (26.58%). On Doppler echocardiography, 16.45% of the patients had pulmonary arterial hypertension (PAH). Conclusion: In light of this work, emphasis should be placed on the quality of antenatal consultations, the quality of management and the regular availability of echocardiography and a cardio-paediatrician in order to reduce morbidity and mortality.

关键词： Heart Disease Congenital Children Senegal

Metallurgical Analysis of Brake Blocks

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Open Journal of Metal 2017年第1期7卷 1-8页

作者： Mathioro Fall Fadel Niang Olivier Hubert Mamadou babacar ndiaye UFR des Sciences de l’Ingénieur Université de Thiès Thiès Sénégal Ecole Doctorale Développement Durable et Société-Université de Thiès Thiès Sénégal LMT-Cachan (ENS-Cachan/UMR/Université Paris Saclay) Cachan France Institut Universitaire et Technologie Université de Thiès Thiès Sénégal

This study focuses on the characterization of train brake blocks. The brake blocks are an essential organ of train speed control system to ensure comfort and safety to passengers and crew. However, poor quality soles can cause a premature wear of the wheels whose consequences are on the one hand, a damaged brake function, and also high repair costs. Samples were carried out on 3 different batches of brake blocks. Their metallurgical characterization consisted of a study of the hardness and microstructural analysis (microstructures and chemical analyzes) of the different samples. The results show that the hardness of some soles is greater than that of the wheel, mainly associated with a cementite microstructure. This can lead to a premature wear of the wheels at the expense of brake blocks.

关键词： Brakes Blocks Wheel Microstructure Hardness Wear

Theoretical and Experimental Study of a Double Air-Pass Solar Thermal Collector with an Insulating Rod of Millet

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Energy and Power Engineering 2018年第3期10卷 106-119页

作者： Mame Mor Diarra ndiaye babacar Diallo Said Abboudi Dorothé Azilinon Laboratoire d’Energétique appliquée (LEA) Ecole Supérieure Polytechnique Dakar Sénégal Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB) Unité Mixte de Recherche 6303 CNRS Université de Bour gogne Franche-Comté UTBM Département COMM Belfort France

In this article, we present the study of a double-pass air insulated by crushed millet stem mixed with gum arabic. The study is carried out based on mathematical models obtained by writing energy conservation laws in the various components of the system, which made it possible to determine the evolution of the air temperature as a function of the length of the absorber and to make a comparison with the experimental results. After comparing the results obtained with those found in the literature, the influence of some physical and geometrical parameters on the performance of the solar thermal collector is presented.

关键词： Solar Collector Double Air-Pass Millet Rod Modeling Performance

Assessment of Insulin Therapy in 281 Children and Adolescents with Type 1 Diabetes in Senegal

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Open Journal of Pediatrics 2022年第1期12卷 283-292页

作者： Djibril Boiro Amadou Sow Aliou Abdoulaye Ndongo Idrissa Basse Lamine Thiam Ndiogou Seck Cheha Fatoumia babacar Niang Modou Guéye Maïmouna Ndour mbaye Ousmane ndiaye Abass Ndao Hospital Dakar Senegal Aristide Le Dantec Hospital Dakar Senegal Diamniadio Children’s Hospital Dakar Senegal Ziguinchor Peace Hospital Dakar Senegal Saint Louis Regional Hospital Dakar Senegal Albert Royer Children’s Hospital Dakar Senegal

Introduction: In Senegal, with the CDIC “Changing Diabetes In children” project, insulin has been made free. The objective of this study was to evaluate the accessibility and modalities of insulin therapy in the management of type 1 diabetes. Methodology: This was a retrospective study including patients followed for type 1 diabetes (T1DM) in hospital between April 2018 and December 2020. Results: 281 patients were included. The mean age was 14.22 years. The mean age at diagnosis was 11.28 years. Ketoacidosis was the main mode of discovery of diabetes at 51.6%. Premix and rapid insulins were most commonly used at 84.7% and 82.9% respectively, most often in combination. The most commonly used treatment regimen was three injections/day in 82.5% of cases. The average daily insulin dose was 0.62 IU/Kg/dr. Of the patients, 219 (78%) were self-monitoring of blood glucose. The average number of blood glucose checks was 1.78 per day. 76 patients (27%) went days without an insulin injection and up to 7 days in 51% of cases. The main reasons were forgetfulness, therapeutic errors and stock-outs. Hypoglycaemia was observed in 14.2%. The average glycated haemoglobin was 10%. Conclusion: Despite the efforts made, there are still challenges to improve access to insulin. The reinforcement of therapeutic education on insulin therapy is essential for a better quality of life of diabetic children and adolescents.

关键词： Diabetes Children Insulin Therapy Senegal