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Solar Controller with Automatic Search Technology for the Maximum Power Point with Autonomy Display

Energy and Power Engineering 2022年第9期14卷 509-522页

作者： Mamadou Sall Ousmane Sow Sega Gueye Gora Diop lemrabott habiboullah Mamadou Wade Gregoire Sissoko Ecole Polytechnique de Thiè s Thi&egrave s S&eacute né gal Institut Universitaire de Technologie. Université Iba Der THIAM de Thi&egrave s S&eacute né gal Groupe International de Recherche en Energie Renouvelable(GIRER) Dakar S&eacute né gal Ecole Supérieure Multinationale de Té lé communication Dakar S&eacute né gal

In our work, we have been interested in conducting technological research on the use of photovoltaic energy for lighting. In fact, we have produced a stand-alone photovoltaic system with automatic search for the maximum power point, consisting of a photovoltaic module, a solar regulator, a storage battery and a digital control by microcontroller. The solar field is connected to the input of the regulator and the battery to its output. When the battery voltage is lower than the regulation voltage, the controller operates the photovoltaic generator at maximum power Pmpp and transfers this power to the output. In addition to the protection function, this regulator ensures tracking of the maximum power point (MPPT) and allows the photovoltaic generator to deliver its power whatever the variation of climatic conditions (sunshine and temperature). The main role of the solar regulator is the continuous monitoring of the state of charge of the battery to ensure its protection against overcharging and excessive discharging, the coupling and decoupling of the user as well as its maintenance. The principle of operation is based on controlling a DC-DC converter by a rectangular “PWM” signal generated by a PIC16F874 microcontroller which also controls the entire system. The results of simulation after realization were presented to illustrate the operation of the regulator by curves.

关键词： Index Terms-Battery Charge/Discharge Regulator PIC16FC874

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A.C. Recombination Velocity as Applied to Determine n<sup>+</sup>/p/p<sup>+</sup>Silicon Solar Cell Base Optimum Thickness

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Energy and Power Engineering 2020年第10期12卷 543-554页

作者： Amadou Mar Ndiaye Sega Gueye Ousmane Sow Gora Diop Amadou Mamour Ba Mamadou Lamine Ba Ibrahima Diatta lemrabott habiboullah Gregoire Sissoko Laboratory of Semiconductors and Solar Energy Physics Department Faculty of Science and Technology University Cheikh Anta Diop Dakar Senegal University Institute of Technology University of Thiès Thiès Senegal Ecole Supérieure Polytechnique de Nouakchott Département Génie Electrique Nouackchott Mauritanie

This work deals with determining the optimum thickness of the base of an n+/p/p+ silicon solar cell under monochromatic illumination in frequency modulation. The continuity equation for the density of minority carriers generated in the base, by a monochromatic wavelength illumination (λ), with boundary conditions that impose recombination velocities (Sf) and (Sb) respectively at the junction and back surface, is resolved. The ac photocurrent is deduced and studied according to the recombination velocity at the junction, to extract the mathematical expressions of recombination velocity (Sb). By the graphic technique of comparing the two expressions obtained, depending on the thickness (H) of the base, for each frequency, the optimum thickness (Hopt) is obtained. It is then modeled according to the frequency, at the long wavelengths of the incident light. Thus, Hopt decreases due to the low relaxation time of minority carriers, when the frequency of modulation of incident light increases.

关键词： Silicon Solar Cell Modulation Frequency Recombination Velocity Base Thickness Wavelength

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Solar Controller with Automatic Search Technology for the Maximum Power Point with Autonomy Display

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Energy and Power Engineering 2022年第9期

作者： mamadou sall ousmane sow sega gueye gora diop lemrabott habiboullah mamadou wade gregoire sissoko

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Diffusion Coefficient at Resonance Frequency as Applied to n+/p/p+ Silicon Solar Cell Optimum Base Thickness Determination

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Journal of Electromagnetic Analysis and Applications 2020年第10期12卷 145-158页

作者： Amadou Mar Ndiaye Sega Gueye Mame Faty Mbaye Fall Gora Diop Amadou Mamour Ba Mamadou Lamine Ba Ibrahima Diatta lemrabott habiboullah Gregoire Sissoko Laboratory of Semiconductors and Solar Energy Physics Department Faculty of Science and Technology University Cheikh Anta Diop Dakar Senegal Ecole Polytechnique de Thiès Thiès Sénégal Département Génie Electrique Ecole Supérieure Polytechnique de Nouakchott Nouakchott Mauritanie

The modelling and determination of the geometric parameters of a solar cell are important data, which influence the evaluation of its performance under specific operating conditions, as well as its industrial development for a low cost. In this work, an n+/p/p+ crystalline silicon solar cell is studied under monochromatic illumination in modulation and placed in a constant magnetic field. The minority carriers’ diffusion coefficient (D(ω, B), in the (p) base leads to maximum values (Dmax) at resonance frequencies (ωr). These values are used in expressions of AC minority carriers recombination velocity (Sb(Dmax, H)) in the rear of the base, to extract the optimum thickness while solar cell is subjected to these specific conditions. Optimum thickness modelling relationships, depending respectively on Dmax, ωr and B, are then established, and will be data for industrial development of low-cost solar cells for specific use.

关键词： Silicon Solar Cell Resonance Frequency Magnetic Field Recombination Velocity Base Thickness

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Shunt Resistance Determination in a Silicon Solar Cell: Effect of Flow Irradiation Energy and Base Thickness

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Journal of Electromagnetic Analysis and Applications 2019年第12期11卷 203-216页

作者： Ousmane Sow Mamadou Lamine Ba Hamet Yoro Ba Mohamed Abderrahim Ould El Moujtaba Youssou Traore Masse Samba Diop habiboullah lemrabott Mamadou Wade Grégoire Sissoko University Institute of Technology University of Thiès Thiès Sénégal Laboratory of Semiconductors and Solar Energy Physics Department Faculty of Science and Technology University Cheikh Anta Diop Dakar Senegal Ecole Polytechnique de Thiès Thiès Sénégal

The concept of the recombination of the minority carrier’s recombination velocity at the junction and in the rear, is used for determination, optimum thickness and then shunt resistance in the base of the silicon solar cell, maintained in steady state and under energy from the irradiation flow of charged particles. Resistance shunt is obtained and modeled through a relationship expressed according to the flow and energy of irradiation imposed on the solar cell.

关键词： Silicon Solar Cell Irradiation Recombination Velocity Shunt Resistance Optimum Base Thickness

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A.C. Recombination Velocity as Applied to Determine n+/p/p+ Silicon Solar Cell Base Optimum Thickness

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Energy and Power Engineering 2020年第10期

作者： Amadou Mar Ndiaye Sega Gueye Ousmane Sow Gora Diop Amadou Mamour Ba Mamadou Lamine Ba Ibrahima Diatta lemrabott habiboullah Gregoire Sissoko

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Contribution to the Study of Diabetic Kidney Disease in a Sub-Saharan Environment: An Example of the Aristide Le Dantec University Hospital in Dakar

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Open Journal of Nephrology 2023年第4期13卷 339-348页

作者： Ahmed Tall lemrabott Maria Faye Niakhaleen Keita Seynabou Diagne Moustapha Faye Bacary Ba Abdou Niang El Hadji Fary Ka Nephrology Department Aristide Le Dantec University Hospital Dakar Senegal Nephrology Department Dalal Jamm National Hospital Center Dakar Senegal

Introduction: Diabetic kidney disease (DKD) is a leading cause of chronic kidney disease and dialysis admission. Few studies are available in Sub-Saharan Africa. The objective of this work was to study the epidemiological, clinical, diagnostic and therapeutic characteristics of DKD in our context. Patients and Methods: We conducted an observational, exhaustive and retrospective study focusing on diabetic patients seen in consultation or hospitalized in the Nephrology Department of at the Aristide Le Dantec University Hospital in Dakar during a period of 5 years from January 1, 2017 to December 31, 2021. Results: Of 4735 patients seen during the study period, 491 had DKD, i.e. a hospital prevalence of 10.36%. The average age was 59.1 ± 11.4 years with a sex ratio of 0.95. Type 2 diabetes predominated with 93.4%. The average duration of diabetes was 11.5 ± 7.6 years. Diabetes was associated with high blood pressure in 78.81% of cases, dyslipidemia in 23.2% of cases, active smoking in 6.7% of cases and obesity in 1.6% of cases. Renal failure was the main reason for referral 72.3%. One hundred and forty-eight patients (30.1%) had uncontrolled diabetes. Macroalbuminuria was found in 64.8% and microalbuminuria in 18.7% of cases. One hundred and eighty-five patients (37.7%) were in Stage V of kidney disease and 137 patients were in Stage III (18.1% in Stage IIIb and 9.8% in Stage IIIa). Diabetic nephropathy was the main etiology at 61.30%. Nephropathy was mixed (diabetic and hypertensive) in 18.12 cases. Renin-angiotensin-aldosterone system (RAAS) blockers were prescribed in 83.5% of patients. Conclusion: The different etiologies encountered during the study show the diversity of diabetic kidney disease. Diabetic nephropathy is not the only kidney damage that can occur in diabetics in our context.

关键词： Diabetic Kidney Disease (DKD) Microalbuminuria Diabetic Nephropathy

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Pathological Fractures in Chronic Hemodialysis Patients in a Teaching Hospital in Senegal: Prevalence and Associated Risk Factors

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Open Journal of Nephrology 2023年第3期13卷 211-219页

作者： Ahmed Tall lemrabott Baratou Coundoul Niakhaleen Keita Maria Faye Moustapha Faye Mansour Mbengue Bacary Ba Seynabou Diagne Abdou Niang El Hadji Fary Ka Department of Nephrology Aristide Le Dantec University Hospital Dakar Senegal Department of Nephrology Dalal Jamm National Hospital Center Dakar Senegal Dialysis Center National Hospital Center of Pikine Pikine Senegal

Introduction: The lack of follow-up and adequate management of chronic kidney disease-mineral and bone disorder (CKD-MBD) in chronic hemodialysis patients is associated with pathological fractures. Few studies are available on the subject in sub-Saharan Africa. The objective of this work was to evaluate the prevalence of pathological fractures in our chronic hemodialysis patients, to analyze their clinical aspects and to determine the factors associated with their occurrence. Patients and Methods: We conducted a retrospective, descriptive and analytical study over 9 years (January 1, 2011, to December 31, 2020) based on the medical records of chronic hemodialysis patients at the CHU Aristide Le Dantec. The diagnosis of pathological fracture was retained in front of any fracture occurring spontaneously or following minimal trauma and confirmed by X-ray. Results: Nineteen cases of pathological fractures were collected with a hospital prevalence of 19.39%. The mean age was 53.32 ± 13.94 years with a sex ratio of 0.36. The average seniority in dialysis was 84.16 ± 29.88 months. Among these patients, one had had 3 episodes of fractures and another 6 episodes. The circumstances of occurrence of the fractures were the fall in 63% of the cases, spontaneously in 37% of the cases. The predominant site of fractures was the femoral neck (47.38% cases). Female gender (p 5 years (p = 0.049), gait disturbances prior to the fracture (p = 0.001), positive CRP (p = 0.028) and the presence of vascular calcifications (p = 0.002) were significantly associated with the occurrence of pathological fractures. Conclusion: This study has identified the factors associated with the occurrence of pathological invoices in hemodialysis patients in our context. These fractures are often associated with the lack of regular biological follow-up due to the low socioeconomic level of our patients.

关键词： Pathological Fractures CKD-MBD Hyperparathyroidism Osteomalacia Adynamic Bone Disease Chronic Hemodialysis

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Pulmonary Hypertension in Chronic Hemodialysis Patients at Aristide Le Dantec University Hospital

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Open Journal of Nephrology 2022年第1期12卷 93-100页

作者： Maria Faye Ahmed Tall lemrabott Niakhaleen Keita Moustapha Faye Romina Ghassani Mansour Mbengue Bacary Ba Seynabou Diagne Abdou Niang El Hadj Fary Ka Nephrology Department Aristide Le Dantec University Hospital Dakar Senegal Cheikh Anta Diop University Dakar Senegal Nephrology Department Dalal Jamm Hospital Dakar Senegal

Introduction: Pulmonary hypertension (PH) is defined as high blood pressure in the lungs. It is recently described as a vascular disease entity in chronic kidney disease, particularly for chronic hemodialysis patients. The aims of this study were to determine the prevalence of PH, to describe clinico-biological and morphological characteristics and to identify risk factors associated with PH in hemodialysis patients. Patients and methods: This is a cross-sectional, descriptive, and analytical study during a period of 8 months from January 1, 2019, to August 31, 2019, in the hemodialysis center of nephrology department of Aristide Le Dantec Hospital. All chronic hemodialysis patients for more than 3 months and with PH confirmed by cardiac doppler ultrasound were included. Results: During the study period, 25/94 patients on chronic hemodialysis, presented with pulmonary hypertension (26.6%). The mean age was 49.3 ± 12.9 years. The sex ratio (M/F) was 0.92. Exertional dyspnea was found in 18 patients (72%). Cardiac auscultation revealed an arrhythmia in 3 patients (12%), augmented second heart sound in 12 patients (48%). On transthoracic doppler ultrasound, pulmonary systolic arterial pressure was on average 51.4 ± 13.2 mmHg. PH was moderate in 13 patients (52%), mild in 9 patients (36%) and severe in 3 patients (12%). The left ventricular ejection fraction was altered in 9 patients (36%). Three patients (12%) had valve calcifications. They were mainly located at aortic valve (8%) and mitral valve (4%). The major risk factors associated to PH in our patients are pathological fractures (p = 0.023), aortic calcifications (p = 0.023), ischemic heart disease (p = 0.023). The duration of hemodialysis represents another favoring factor (p = 0.042). Also implicated are arrhythmias (p = 0.004), high cardiac index (p = 0.043), ventricular dilatation (p = 0.034) and left atrial dilation (p = 0.015), as well as dilation of the inferior vena cava (p = 0.048).

关键词： Pulmonary Hypertension Chronic Hemodialysis Patients Transthoracic Doppler Ultrasound Dakar

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Acute Renal Failure in the Elderly in the Nephrology Department of Aristide Le Dantec Hospital in Senegal: About 45 Cases

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Open Journal of Nephrology 2023年第4期13卷 451-463页

作者： Arlette Géraldine Nguea Ndjame Ameth Dieng Vincent Ebenezer Ngamby Mamadou Coume El Hadji Fary Ka Maria Fall Ahmed Tall lemrabott Mouhamadou Moustapha Cisse Abdou Niang Department of Clinical Sciences Faculty of Medicine and Pharmaceutical Sciences University of Douala Douala Cameroon Central Hospital of Yaoundé Yaoundé Cameroon Health Sciences Training and Research Unit University of Thiès Thiès Senegal Regional Hospital of Thiès Thiès Senegal Faculty of Medicine Pharmacy and Odontology Cheikh Anta Diop University Dakar Senegal National University Hospital of Fann Dakar Senegal Aristide Le Dantec Hospital Dakar Senegal Dalal Jamm National University Hospital of Guédiawaye Dakar Senegal

Introduction: The incidence of acute renal failure (ARF) increases with age. In Senegal, few studies have described the epidemiology of ARF in the elderly. The aim of our study is to establish the epidemiological profile of elderly patients with ARF, identify the causes of ARF in the elderly and assess treatment and prognosis. Methods: We conducted a descriptive and retrospective study over a five-year period from 2011 to 2015 involving patients aged 60 and over, treated for ARI during the study period. Data entry and analysis were done on Epi info 7.3. Results: We included a total of 45 patients. The prevalence of ARF was 3.34%. The mean age was 70.31 years (60 - 83) and the sex ratio was 3.5. Phytotherapy was found in 68.9%, hypertension was found in 68.9%, and diabetes was found in 31.1%. Prostate hypertrophy was found in 53.4% of patients. Pre-renal ARF was the most common (46.6%). Most of the cases, 66.67%, were at Stage 3 of KDIGO. The most common etiologies were respectively tumor (35.5%) and infection (20%). The most common complications were respectively hyperkalemia (33.3%) and hyponatremia (33.3%). Recovery was complete in 62.6% of cases, partial in 37.8% of patients and 13.3% of patients ended up on chronic hemodialysis. Mortality was 4.4%. Conclusion: Herbal medicine, hypertension and diabetes are frequently associated with ARF in the elderly. This justifies increased monitoring of the elderly subject with these conditions in order to subject him to early and appropriate care.

关键词： Acute Renal Failure Elderly Epidemiology

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