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Nanosecond pulse and dual-wavelength Q-switched 1.5 μm fiber laser using MAX phase Cr2TialC2 saturable absorber

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Optoelectronics Letters 2025年第1期21卷 7-12页

作者： ahmed Shakir al-HITI Hiba HASSAN Department of Electrical Engineering Faculty of Engineering University of Anbar Department of Laser and Optoelectronics Engineering University of Technology-Iraq

We demonstrated a new type of MAX phase material, chromium titanium aluminum carbide（Cr2TialC2） polymer film, to generate a passively Q-switched erbium-doped fiber laser（EDFL）. The film thickness was measured to be around 45 μm, which was fabricated using the embedding method with polyvinyl alcohol（PVA） polymer as hoster. The saturable absorber（SA） film demonstrates a dual-wavelength passively Q-switched EDFL which operates at 1 531 nm and 1 560.19 nm, respectively. The Q-switching pulse duration could be varied from 2.46 μs to 770 ns, while the repetition rate varied from 92.76 kHz to 106.6 kHz with an increasing input pumping range from 154 mW to 300 mW. The maximum output power and pulse energy of 15.05 mW and 141.18 nJ were obtained at the maximum input power of 300 mW, respectively.

关键词： Saturable absorbers

Enhancing Solar Photovoltaic Efficiency:A Computational Fluid Dynamics Analysis

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Energy Engineering 2025年第1期122卷 153-166页

作者： Rahool Rai Fareed HussainMangi Kashif ahmed Sudhakar Kumaramsay Faculty of Mechanical and Automotive Engineering Universiti Malaysia Pahang Al-Sultan AbdullahPekan26600PahangMalaysia Faculty of Engineering Science&Technology Hamdard UniversityKarachi74600Pakistan Electrical Engineering Department SUKKUR IBA UniversitySukkur65200Pakistan Berlin School of Business and Innovation BSBI Faculty of Computer Science and InformaticsBerlin12043Germany Automotive Engineering Centre University Malaysia Pahang Al Sultan AbdullahPekan26600PahangMalaysia Centre for Research in Advanced Fluid&Processes(Fluid Centre) Universiti Malaysia Pahang Al-Sultan Abdullah(UMPSA)Paya BesarKuantan26300PahangMalaysia

The growing need for sustainable energy solutions,driven by rising energy shortages,environmental concerns,and the depletion of conventional energy sources,has led to a significant focus on renewable *** energy,among the various renewable sources,is particularly appealing due to its abundant ***,the efficiency of commercial solar photovoltaic(PV)modules is hindered by several factors,notably their conversion efficiency,which averages around 19%.This efficiency can further decline to 10%–16%due to temperature increases during peak sunlight *** study investigates the cooling of PV modules by applying water to their front surface through Computational fluid dynamics(CFD).The study aimed to determine the optimal conditions for cooling the PV module by analyzing the interplay between water film thickness,Reynolds number,and their effects on temperature reduction and heat *** CFD analysis revealed that the most effective cooling condition occurred with a 5 mm thick water film and a Reynolds number of *** specific parameters were found to maximize the heat transfer and temperature reduction *** finding is crucial for the development of practical and efficient cooling systems for PV modules,potentially leading to improved performance and longevity of solar *** cooling fluids or advanced cooling techniques that might offer even better efficiency or practical benefits.

关键词： PV module efficiency water film thickness reynolds number CFD analysis PV/T renewable energy

Vascular endothelial growth factor:a double-edged sword in the development of white matter lesions

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Neural Regeneration Research 2025年第1期20卷 191-192页

作者： Narek Manukjan Daniel Fulton Zubair ahmed WMatthijs Blankesteijn Sébastien Foulquier Department of Pharmacology and Toxicology Maastricht UniversityMaastrichtThe Netherlands CARIM-School for Cardiovascular Diseases Maastricht UniversityMaastrichtThe Netherlands Neuroscience and Ophthalmology Institute of Inflammation and AgeingUniversity of BirminghamEdgbastonBirminghamUK Centre for Trauma Sciences Research University of BirminghamEdgbastonBirminghamUK MHeNs-School for Mental Health and Neuroscience Maastricht UniversityMaastrichtThe Netherlands Department of Neurology Maastricht University Medical CenterMaastrichtThe Netherlands

As the population ages,the burden of age-related diseases becomes ***,over 55 million people suffer from dementia worldwide,with alzheimer’s disease being the most common ***,it is becoming clearer that underlying vascular pathology such as cerebral small vessel disease(cSVD)may be a more detrimental cause for dementia(Cuadrado-Godia et al.,2018).It is estimated that 10%-30%of the elderly population and 35%-90%of all dementia patients exhibit signs of *** term cSVD refers to pathology affecting the small vessels of the brain,which can lead to lacunar cerebral infarcts,enlarged perivascular spaces,and cortical hemorrhages(Cuadrado-Godia et al.,2018).CSVD is often associated with cognitive decline,gait problems,and dementia(Cuadrado-Godia et al.,2018).

关键词： pathology becoming white

Relationships between land use types and urban heat island intensity in Hulu Langat district,Selangor,Malaysia

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Ecological Processes 2023年第1期12卷 461-474页

作者： Muhammad Rendana Wan Mohd Razi Idris Sahibin Abdul Rahim Hazem Ghassan abdo Hussein almohamad ahmed Abdullah al Dughairi Motrih al-Mutiry Department of Chemical Engineering Faculty of EngineeringUniversitas SriwijayaIndralaya 30662South SumatraIndonesia Department of Earth Sciences and Environment Faculty of Science and TechnologyUniversiti Kebangsaan Malaysia43600 BangiSelangorMalaysia Department of Environmental Science Faculty of Science and Natural ResourcesUniversiti Malaysia Sabah88400 Kota KinabaluSabahMalaysia Geography Department Faculty of Arts and HumanitiesTartous UniversityTartousSyria Department of Geography College of Arabic Language and Social StudiesQassim UniversityBuraydah 51452Saudi Arabia Department of Geography College of ArtsPrincess Nourah Bint Abdulrahman UniversityRiyadh 11671Saudi Arabia

Background Urban heat island(UHI)is an urban climate phenomenon that primarily responds to urban conditions and land use *** extent of hard surfaces significantly influences the thermal properties of the *** address this issue,a novel approach quantifying the association between land use and UHI is *** study offers a new technique for effectively estimating the effect of land use on the UHI intensity using the combination of urban heat intensity index(UHII)and land contribution index(LCI)derived from Landsat 8 OLI *** time-series thermal effect of land use on the UHI intensity can be determined according to the ratio in mean temperature between specific land use and the whole study *** study was conducted in the Hulu Langat district,Malaysia during *** The UHI intensity rose from 0.19 in 2014 to 0.70 in *** negative value of LCI for vegetation areas and water bodies obtained its negative contribution to the urban heat island,while the positive value of LCI for bare areas and built-up areas showed its positive effect on the urban heat *** LCI value for urban areas showed a significant increase in the 7 years such as 0.51,0.66,0.69,and 0.75 for periods 2014,2016,2018,and 2021,*** change in LCI from 2014 to 2021 for the transformation of bare area and forest was recorded to be 0.23 and−0.02,***,the conversion of forests into urban areas had a negative effect on the increment of UHI *** Overall,these findings are useful for policy-making agency in developing an effective policy for reducing high UHI intensity and planning long-term land use management.

关键词： Geospatial technology Urban heat island Land contribution index Land surface temperature Environment

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Maximizing the Benefit of Rate Transient Analysis for Gas Condensate Reservoirs

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Energy Engineering 2021年第5期118卷 1411-1423页

作者： Mahmoud abdo Tantawy ahmed A.M.Elgibaly ahmed Mohamed Farag Faculty of Petroleum and Mining Engineering Suez UniversitySuezEgypt Abu Qir Petroleum Company AlexandriaEgypt

In recent years,many trials have been made to use the Rate Transient Analysis(RTA)techniques as a method to describe the gas condensate *** problem with using these techniques is the multi-phase behavior of the gas condensate ***,the Pressure Transient Analysis(PTA)is commonly used in this case to analyze the reservoir *** this paper,we are going to compare the results of both PTA and RTA of three wells in gas condensate *** comparison showed a great match between the results of the two mentioned techniques for the first time using a reference GOR of 75,000 SCF/***,we concluded that we could depend on RTA instead of PTA to spare the cost associated with the PTA in the gas condensate reservoirs.

关键词： Rate transient analysis production data analysis well testing permeability skin factor gas condensate

Investigation of a New Formula for Gurney Velocity Estimation

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火炸药学报 2018年第4期41卷 340-344页

作者： Tamer Elshenawy ahmed Elbeih Qing Ming Li Gamal M. abdo Technical Research Centre Cairo Egypt Military Technical College Kobry Elkobbah Cairo Egypt The University of Manchester School of Mechanical Aerospace and Civil Engineering Manchester UK Mechanical Engineering Department Modern Acade

The formula for the analytical calculations of the shaped charge jetting parameters exhibit an explicit dependence upon the Gurney velocity of an explosive *** attempts have been done to approximate the characteristic constant 2E^(1/2) and to make its use more *** is shown herein that the characteristic Gurney velocity parameter depends on the ratio of the Chapman Jouguet-pressure to explosive impulse ratio by the formula:2E^(1/2)=0.2415(P_(CJ)/I_(SP)ρ_0)-970.76,where PCJis the Chapman Jouguet pressure(Pa),ISPis the specific impulse of the explosive used as a monopropellant(N·s/kg)andρois the explosive density(kg/m^3).The proposed empirical formula was found to be reasonable and quite accurate approximation that can be implemented over a wide range of explosives,where the maximum deviation between the measured and the calculated Gurney velocities was nearly 6%.Besides,the proposed approach has been used analytically to calculate the jet tip velocity of a small caliber shaped charge,which is measured *** difference between the measured and the calculated jet tip velocity was only 1.6%.

关键词：火药理论研究化学分析

Seismic retrofitting of severely damaged RC connections made with recycled concrete using CFRP sheets

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Frontiers of Structural and Civil Engineering 2020年第2期14卷 554-568页

作者： Yasmin MURAD Wassel al BODOUR ahmed ASHTEYAT Civil Engineering Department The University of JordanAmman 11942.Jordan

An experimental and numerical program is carried out in this research to investigate the influence of CFRP sheets on the cyclic behavior of unconfined connections made with recycled *** is partially replaced by silica fume,iron flling and pulverised fuel ash using two different percentages:15%and 20%.Each specimen is partially loaded at the first stage and then specimens are repaired using CFRP *** repaired specimens are then laterally loaded until *** addition,a finite element model is built in ABAQUS and verfed using the experimental *** experimental results have shown that the repaired specimens have regained almost double the capacity of the un-repaired specimens and hence the adopted repair configuration is recommended for retroftting seismically vulnerable RC *** cement replacement percentage by silica fume,fuel ash or iron flling from 15%to 20%has reduced joint carrying capacity and weakened the *** is recommended using 15%pulverised fuel ash or silica fume as cement partial replacement to enhance the strength and ultimate drift of beam-column joints under cyclic *** filling concrete is also recommended but the enhancement is relatively less than that found with pulverised fuel ash concrete and silica fume concrete.

关键词： retrofitting CFRP sheets recycled concrete pulverised fuel ash silica fume cyclic beam-column connections

A Participatory GIS Approach to Identify Critical Land Degradation Areas and Prioritize Soil Conservation for Mountainous Olive Groves(Case Study)

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Journal of Mountain Science 2014年第3期11卷 782-791页

作者： ahmed al-WADAEY Feras ZIADAT Soil and Water Department Faculty of Agriculture Sana’a University Sana’a 00967 the Republic of Yemen International Center for Agricultural Research in the Dry Areas (ICARDA) P.O. Box 950764 – Amman 11195 Jordan

Climate change scenarios predict an increase in the frequency of heavy rainfall events in some areas. This will increase runoff and soil erosion, and reduce agricultural productivity, particularly on vulnerable mountainous agricultural lands that is already exhibiting high rates of soil erosion. Haphazard implementation of soil and water conservation （SWC） interventions on scattered fields is inefficient in reducing soil erosion. The objective of this study was to identify areas at high risk of erosion to aid the design and implementation of sustainable SWC using GIS analysis and farmers＇ participation approach. A 25 m digital elevation model （DEM） was used to derive layers of flow accumulation, slope steepness and land curvature, which were used to derive an erosion-risk （priority） map for the whole watershed. Boundaries of farmers＇ fields were mapped and verified by the community and each field was classified into high, moderate or low erosion risk. Fields with low flow accumulation （top of hill） and/or steep slope and/or convex slope were assigned high erosion risk and therefore high implementation priority. The study showed that more than 54% of the fields were classified into high erosion risk areas. Accordingly, a community-watershed plan was established, revised and approved by the *** loans to implement SWC measures were distributed to 100 farmers based on the priorities of their fields. Judged by local farmers and using 16 randomly selected fields, 90% of the targeted areas were correctly identified using the erosion risk map. After two years, the conservation measures had led to marked improvement of soil conservation. The approach is simple and easy to comprehend by the community and provides scientific basis to prioritize the implementation of SWC and to target the most degraded areas, which amplify the impact of these in reducing the vulnerability to land degradation.

关键词： Flow accumulation Soil erosion Community-conservation plan Olive Priority map

CATIONIC RING-OPENING POLYMERIZATION OF TETRAHYDROFURAN WITH KEGGIN-TYPE HETEROPOLYCOMPOUNDS AS SOLID ACID CATalYSTS

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Chinese Journal of Polymer Science 2010年第3期28卷 305-310页

作者： ahmed Aouissi Salim Salem al-Deyab Hassan al-Shehri Chemistry Department College of ScienceKing Saud UniversityRiyadhKSA

Three Keggin-type heteropolyanions, namely H3PMo12O40-13H2O, （NH4）3PMo12O40·4H2O and H3PW12O40·13H2O were prepared and tested in the ring-opening polymerization reaction of tetrahydrofuran. The effects of the counter-cation （H＋, NH4＋） and the peripheral atoms （Mo, W） on the polymerization were investigated. It has been found that when the protons of H3PMo12O40·13H2O were replaced by the ammonium cations the polymerization rate decreased dramatically. Whereas, when the peripheral atoms （Mo） were replaced by their homologous （W）, the polymerization rate increased twofold. As for the viscosity average molecular weight （My） of polymer products, it was found that the high molecular weight （7930） was obtained by using H3PW12O40·13H2O. The molecular weight （My） obtained by H3PMo12O40·13H2O and （NH4）H3PMo12O40·13H2O was 6470 and 6810, respectively.

关键词： Tetrahydrofuran Heteropoly compounds Ring opening polymerization Cyclic ether Solid acid