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Optimizing solar energy efficiency with an improved hill-climbing maximum power point tracking control approach: hardware implementation

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Clean Energy 2024年第5期8卷 167-176页

作者： Yassine El Alami Elmostafa Chetouani Hamza Mokhliss Fatima Ouerradi Mohssin Aoutoul Said Bounouar Rachid Bendaoud ahmed Faize Redouane Rmaily Laboratory of Electronics Instrumentation and EnergeticFaculty of SciencesChouaïb Doukkali UniversityB.P 20El JadidaMorocco Laboratory ElectronicsInstrumentation and EnergyExploitation and Processing of Renewable EnergyDepartment of PhysicsFaculty of SciencesUniversity of Chouaïb DoukkaliEl JadidaMorocco STIC Lab. Department of PhysicsChouaïb Doukkali UniversityEl JadidaMorocco Complex Cyber Physical Systems Laboratory National Higher School of Arts and CraftsHassan II UniversityCasablancaMorocco Interdisciplinary Laboratory for Research in Science Educationand TrainingHigher School of Education and Training-BerrechidHassan First UniversityBerrechidMorocco Department of Physics Polydisciplinary FacultyUniversity of Mohamed PremierNadorMorocco

This article implements maximum power point tracking(MPPT)based on the improved hill-climbing algorithm for photovoltaic(PV)systems feeding resistive loads.A direct current-to-direct current boost converter is inserted between the PV system and the load to achieve *** converter is managed using MPPT based on the hill-climbing *** objective of this paper is to optimize the code program to achieve the best compromise between accuracy and rapidity by implementing this algorithm using a *** PV systems are tested under identical meteorological *** the first,an improved hill-climbing MPPT controller is used whereas,in the second,the conventional version is *** experimental results obtained show a signifi-cant enhancement in terms of speed for the improved algorithm with a value of 0.4 s for the response time and 3%for the oscillation power;those values remain satisfactory in terms of precision of the algorithm compared with the conventional system studied and the compared algorithm from the literature.

关键词： DC/DC boost converter hardware implementation improved hill climbing MPPT photovoltaic system

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Immunovirological Discordance and Associated Factors among People Living with HIV under Antiretroviral Treatment at Hôpital de Jour de Donka, Guinea

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Open Journal of Medical Microbiology 2024年第2期14卷 93-104页

作者： Mariama Sadjo Diallo Djiba Kaba Charles Tchibinda Delicat Issiaga Diallo Boh Fanta Diane Doufin Traore Ousmane Niabaly Oumar Mouctar Diallo Ouo-Ouo Yaramon Kolie Aly Patrice Kamano Pascal Koivogui ahmed Sékou Keita mohamed Macire Soumah Thierno Mamadou Tounkara mohamed Cisse Facult des Sciences et Techniques de la Sant Universit Gamal Abdel Nasser de Conakry Conakry Guine Laboratoire de Biologie Molculaire Nestor Bangoura/Helene Labrousse Hpital de Jour Donka CHU Donka Conakry Guine Centre dExcellence Africain Pour la Prvention et le Contrle des Maladies Transmissibles Conakry Guine Service de Dermatologie-Vnrologie CHU Donka Conakry Guine

The antiretroviral treatment (ART) has significantly reduced the number of new HIV/AIDS infections and related deaths. However, cases of immunovirological discordance (IVD) are found in various locations. The objective of this study was to determine the profile of People living with HIV (PLHIV) with IVD and to identify associated factors. We conducted a cross-sectional study based on the records of PLHIV under ART for at least 6 months, followed at Hpital de Jour Donka from 2015 to 2017, and having both viral load (CV) and CD4 T-cell count. Prevalence of IVD was 34.57%, with 23.87% for immunological discordance (ID) and 10.7% for virological discordance (VD). Females were predominant (66.26%), and male gender influenced IVD with a statistically significant difference (p = 0.006) and was associated with VD (p = 0.007). The average age was 38.77 11.30 years. PLHIV were classified at WHO stages 3 and 4 (86.01%). The median initial haemoglobin level was 11.5 g/L [3.2 - 12]. The mean initial CD4 T-cell count was 272.84 cells/mm3 201.6. The median initial viral load (VL) was 147,337 copies/mL [1092 - 31,675,000]. The initial CD4 T-cell count 3 was associated with IVD with a statistically significant difference (p = 0.0009) and correlated with ID (p = 0.000). Prurigo was associated with IVD with a statistically significant difference (p = 0.003). Cerebral toxoplasmosis was not associated with IVD but was associated with ID (p = 0.04). This study allowed us to describe the profile of PLHIV with IVD. The main associated factors were male gender, initial CD4 T-cell count 3, toxoplasmosis, prurigo, and herpes zoster.

关键词： HIV Antiretroviral Treatment (ART) Immunovirological Discordance Donka Guinea

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Delayed Grafting as a Valid Technique in Burn Management: Experience from a Burn Unit in Oman

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Modern Plastic Surgery 2024年第1期14卷 9-14页

作者： Taif Alsafy Joe Jacob Anish Thadathil Elias ahmed Salah El Din Salim Mohammed Ghawas Majid Tariq Saud Albusaidi ahmed Al Jabri Al Anood Al Hadhrami Mutazz Obeid Al Khaldi Moath Abdelhamid Shummo Karim mohamed Haridi Aml Eid Saleh Said Al-Busaidi Department of Plastic and Reconstructive Surgery Sultan Qaboos Hospital Salalah Oman ENT Department Al Nahdha Hospital Muscat Oman Department of Plastic Reconstructive and Craniofacial Surgery Khoula Hospital Muscat Oman

Background: Early excision and grafting has been the preferred method of managing major burns around the world since 1970. Considering the advances in health care and the development of new antibiotics over the past 50 years, delayed grafting as a technique for the management of burns over 15%-20% of total body surface area (TBSA) could have comparable results to that of early excision. This study aims to highlight the outcomes of practicing delayed grafting in burn patients. Methods: A case series analysis was performed of 51 patients who were admitted to the burns unit in Sultan Qaboos Hospital Salalah with over 20% TBSA between January 2014 and December 2019. The patients received prophylactic antibiotics and silver sulphadiazine dressing until the burn eschar had completely separated, followed by grafting. Results: Two patients were lost during the entire duration of the study. The mortality rate was comparable to that of early excision, while the rate of hypertrophic scarring was lower than the range reported by other studies. Conclusion: In the management of patients with over 20% TBSA, delayed grafting after complete separation of eschar is still a valid technique.

关键词： Burns Burn Units Burn Management Delayed Grafting Major Burns Treatment Efficacy

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Ecological risk assessment of surficial sediment by heavy metals from a submerged archaeology harbor,South Mediterranean Sea,Egypt

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Acta Geochimica 2020年第2期39卷 226-235页

作者： Maha ahmed mohamed Abdallah ahmed mohamed Badr-ElDin Marine Pollution Lab National Institute of Oceanography and FisheriesAlexandriaEgypt Oceanography Department Faculty of ScienceAlexandria UniversityAlexandriaEgypt

A protected semi-enclosed embayment,the Eastern Harbor(EH),is situated in the central sector of the Mediterranean coast of Alexandria,*** is a famous fishing dock and water-sport center and its importance arose after the discovery of the Ptolemaic royal quarter of ancient *** protect this national treasure and improve its environmental health,the untreated anthropogenic effluents,which continued for decades into the EH since 1992,must be totally ***,it is an important issue to continually monitor and asses the environmental status of the *** sediment texture,total organic carbon,and the accumulation,distribution,and ecological risks of Cd,Cr,Pb,As,Hg and A1 were determined with a total of 14 surficial sediments samples collected in the EH during *** contents were compared to the literature data to assess the pollution status of *** factors,Degree of contamination(mCd)and potential ecological risk were calculated as a criterion of possible *** mCd calculation produces an overall average value for a range of pollutants,in the present study the contamination factor that provides a measure of the degree of overall contamination in the surface layers in a particular sampling site may provide a better indication of the state of pollution in the EH sediments than other indicators.

关键词： Heavy metals Eastern harbor Enrichment factors Degree of contamination Potential ecological risk

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Static and dynamic stability responses of multilayer functionally graded carbon nanotubes reinforced composite nanoplates via quasi 3D nonlocal strain gradient theory

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Defence Technology（防务技术） 2022年第10期18卷 1778-1809页

作者： ahmed Amine Daikh mohamed Sid ahmed Houari mohamed Ouejdi Belarbi Salwa A.mohamed mohamed A.Eltaher Laboratoire D'Etude des Structures et de Mecanique des Materiaux Departement de Genie CivilFacultedes Sciences et de La TechnologieUniversite Mustapha Stambouli B.P.305R.P.29000MascaraAlgeria Laboratoire de Genie Energetique et Materiaux LGEMUniversite de BiskraB.P.145R.P07000BiskraAlgeria Department of Engineering Mathematics Zagazig UniversityP.O.Box 44519ZagazigEgypt Faculty of Engineering Mechanical Engineering DepartmentKing Abdulaziz UniversityP.O.Box 80204JeddahSaudi Arabia Faculty of Engineering Mechanical Design and Production DepartmentZagazig UniversityP.O.Box 44519ZagazigEgypt

This manuscript presents the comprehensive study of thickness stretching effects on the free vibration,static stability and bending of multilayer functionally graded(FG)carbon nanotubes reinforced composite(CNTRC)*** nanoscale and microstructure influences are considered through a modified nonlocal strain gradient continuum *** on power-law functions,four different patterns of CNTs distribution are considered in this analysis,a uniform distribution UD,FG-V CNTRC,FG-X CNTRC,and FG-O CNTRC.A 3D kinematic shear deformation theory is proposed to include the stretching influence,which is neglected in classical ***'s principle is applied to derive the governing equations of motion and associated boundary *** solutions are developed based on Galerkin method to solve the governing equilibrium equations based on the generalized higher-order shear deformation theory and the nonlocal strain gradient theory and get the static bending,buckling loads,and natural frequencies of *** with previous works is presented.A detailed parametric analysis is carried out to highlight the impact of thickness stretching,length scale parameter(nonlocal),material scale parameter(gradient),CNTs distribution pattern,geometry of the plate,various boundary conditions and the total number of layers on the stresses,deformation,critical buckling loads and vibration *** new results are also reported in the current study,which will serve as a benchmark for future research.

关键词： 3D shear deformation theory Free vibration Buckling Bending Galerkin method Functionally graded nanotube Nonlocal strain gradient theory

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Magnetoresistive properties of Ni-doped La_(0.7)Sr_(0.3)MnO_3 manganites

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Rare Metals 2016年第7期35卷 551-558页

作者： ahmed mohamed ahmed Abd El-Moez ahmed mohamed Medhat Abdelrady Abdellateef Hassan ahmed Abd El-Ghanny Physics Department Faculty of ScienceSohag University

Lao.7Sr0.3Mnl_xNixO3 （x = 0, 0.025, 0.050 and 0.075） ceramics were prepared by the conventional solid-state reaction method. The partial substitution of Mn by Ni2＋ leads to a decrease in cell volume as well as a structural transition from the rhombohedral to the orthorhombic structure. Ni2＋ doping increases the electrical resistivity, decreases the semiconductor-metal transition temperature （Tms） and relatively enhances the room temperature magnetoresistance （MR）, especially in x = 0.025 and around Tins. With respect to conduction mechanism, the small polaron hopping （SPH） and the variable range hopping （VRH） models were used to ex- amine conduction in the semiconducting region.

关键词： Manganites X-ray diffraction Structure Electrical resistivity Magnetoresistance

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Friction and wear of sand-contaminated lubricated sliding

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Friction 2018年第4期6卷 457-463页

作者： mohamed ahmed RAMADAN Faculty of Engineering at Helwan Helwan University

This paper reports a test investigation of friction and wear responses from sand contaminated lubricated sliding. The influence of sand contaminants on wear and friction is characterized. Analyses are completed utilizing segments of piston ring sliding against the cylinder liner. Paraffin oil, with and without sand contaminants, is utilized. The effects of the concentration and particle size of sand are examined. Based on the observations in the present work, we found that friction and wear increase with sand concentration in the lube. Solid proposals ought to be considered, in order to enlighten the general population on the importance of changing a car engine's oil filter regularly.

关键词： sand contamination lubrication oil abrasive wear lubricated sliding

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Developing Check-Point Mechanism to Protect Mobile Agent Free-Roaming Against Untrusted Hosts

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Computers, Materials & Continua 2022年第8期72卷 3849-3862页

作者： Tarig mohamed ahmed Department of Information Technology FCITKing Abdulaziz UniversityJeddahSaudi Arabia

Mobile Agent has many benefits over traditional distributed systems such as reducing latency,bandwidth,and *** Agent Systems are not fully utilized due to security *** paper focuses on mobile agent protection against malicious hosts.A new security mechanism called Checkpoints has been *** Mechanism(CPM)aims to protect Mobile Agent against malicious hosts in case of Capturing and Integrity *** assumes using a free-roaming mobility mechanism by Mobile agent *** main idea behind CPM is to generate multiple versions of Mobile *** multiple version is used to recover Mobile Agent from Capturing and Integrity attacks by untrusted *** versions are kept in Recovery Host(RH).RH plays a key role in CPM by controlling and monitoring MAs’recovery processes.A prototype method has been used to prove the feasibility of *** p https://***/Default-305-ARrototype was implemented by using *** framework and C#.full discussion for several scenarios has been done to analyze the feasibility and performance for *** found from this research,CPM has a strong ability to protect Mobile Agents from Capturing and Integrity attacks *** addition,there is no negative impact on the overall performance of the mobile agent system.

关键词： Mobile agent security capturing integrity attacks

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Anti-wear properties evaluation of frictional sliding interfaces in automobile engines lubricated by copper/graphene nanolubricants

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Friction 2020年第5期8卷 905-916页

作者： mohamed Kamal ahmed ALI Xianjun HOU mohamed AAABDELKAREEM Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of TechnologyWuhan 430070China Automotive and Tractors Engineering Department Faculty of EngineeringMinia UniversityEl-Minia 61111Egypt Hubei Collaborative Innovation Center for Automotive Components Technology Wuhan 430070China

Owing to the significance of improving fuel economy, reducing emissions, and extending the durability of engine components, this study focused on the tribological performance of nano-additives. In this study, copper (Cu) and graphene (Gr) nanomaterials were dispersed in a fully formulated engine oil (5W-30) with different concentrations. The tribological trials were investigated under various speeds and loads, utilizing a reciprocating tribometer to mimic the ring/liner interfaces in the engine. The frictional surface morphologies were com-prehensively analyzed using electron probe X-ray microanalysis (EPMA), field emission scanning electron microscopy (FESEM), energy dispersive spectrometer (EDS), and three dimensional (3D) surface profilometry to explore the mechanisms responsible for improving the tribological performance of the frictional sliding parts in the engine. The tribological test results illustrated that lubrication by nano-additives reduced the wear rate (WR) and friction coefficient (COF) by 25%–30% and 26.5%–32.6%, respectively, as compared with 5W-30. The results showed that this is a promising approach for increasing the durability and lifespan of frictional sliding components and fuel economy in automobile engines.

关键词： engine tribology nanomaterial nanolubricant friction wear tribofilm

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Experimental and parametrical investigation of pre-stressed ultrahigh-performance fiberreinforced concrete railway sleepers

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Frontiers of Structural and Civil Engineering 2023年第3期17卷 411-428页

作者： Sayed ahmed Hossam ATEF mohamed HUSAIN Department of Structural Engineering Faculty of EngineeringZagazig UniversityZagazig 44519Egypt Track Work Department National Authority for TunnelsCairo 11522Egypt

In this study,ultrahigh-performance fiber-reinforced concrete(UHPFRC)used in a type B70 concrete sleeper is investigated experimentally and *** main parameters investigated are the steel fiber volume fractions(0%,0.5%,1%,and 1.5%).Under European standards,35 UHPFRC sleepers are subjected to static bending tests at the center and rail seat sections,and the screw on the fastening system is pulled *** first cracking load,failure load,failure mode,crack propagation,load–deflection curve,load–crack width,and failure load from these tests are measured and compared with those of a control sleeper manufactured using normal concrete *** accuracy of the parametric study is verified ***,the results of the study are applied to UHPFRC sleepers with different concrete volumes to investigate the effects of the properties of UHPFRC on their *** and parametric study results show that the behavior of UHPFRC sleepers improves significantly when the amount of steel fiber in the mix is *** manufactured using UHPFRC with a steel fiber volume fraction of 1%and a concrete volume less than 25%that of standard sleeper B70 can be used under the same loads and requirements,which contributes positively to the cost and surrounding environment.

关键词： pre-stressed concrete sleeper ultrahigh performance fiber-reinforced concrete pull-out test static bending test steel fiber aspect ratio volume fraction

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