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An Improved Design of a Fully Automated Multiple Output Micropotentiometer

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Energy and Power Engineering 2010年第2期2卷 103-110页

作者： Hala Mohamed Abdel Mageed ahmed faheem zobaa Mohamed Helmy Abdel Raouf Abla Hosni Abd El-Rahman Mohamed Mamdouh Abdel Aziz National Institute for Standards GizaEgypt University of Exeter ExeterUK Cairo University GizaEgypt

This paper describes in details a new design of a fully automated multiple output micropotentiometer (?pot). A prototype has been built at the National Institute for Standards (NIS), Egypt to establish this highly improved AC voltage source in the millivolt range. The new device offers three different outputs covering a wide frequency range from only one outlet. This valuably supports the precise sourcing ranges of low AC voltage at NIS. The design and the operation theory of this prototype have been discussed in details. An automatic calibration technique has been introduced through specially designed software using the LabVIEW program to enhance the calibration technique and to reduce the uncertainty contributions. Relative small AC-DC differences of our prototype in the three output ranges are fairly verified. The expanded uncertainties of the calibration results for the three output ranges have been faithfully estimated. However, further work is needed to achieve the optimum performance of this new device.

关键词： Multiple Output μpot AC-DC Transfer Standard Single Junction Thermal Converter Calibration Uncertainty

Electrical Performance Study of a Large Area Multicrystalline Silicon Solar Cell Using a Current Shunt and a Micropotentiometer

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Engineering（科研） 2010年第4期2卷 263-269页

作者： Hala Mohamed Abdel Mageed ahmed faheem zobaa ahmed Ghitas Mohamed Helmy Abdel Raouf Mohamed Sabry Abla Hosni Abd El-Rahman Mohamed Mamdouh Abdel Aziz National Institute for Standards University of Exeter National Research Institute of Astronomy and Geophysics

In this paper, a new technique using a Current Shunt and a Micropotentiometer has been used to study the electrical performance of a large area multicrystalline silicon solar cell at outdoor conditions. The electrical performance is mainly described by measuring both cell short circuit current and open circuit voltage. The measurements of this cell by using multimeters suffer from some problems because the cell has high current intensity with low output voltage. So, the solar cell short circuit current values are obtained by measuring the voltage developed across a known resistance Current Shunt. Samples of the obtained current values are accurately calibrated by using a Micropotentiometer (μpot) thermal element (TE) to validate this new measuring technique. Moreover, the solar cell open circuit voltage has been measured. Besides, the cell output power has been calculated and can be correlated with the measured incident radiation.

关键词： Large Area Multicrystalline Silicon Solar Cell Current Measurements Calibration Current Shunt Micropotentiometer Short Circuit Current Open Circuit Voltage

Temperature Effects on the Electrical Performance of Large Area Multicrystalline Silicon Solar Cells Using the Current Shunt Measuring Technique

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Engineering（科研） 2010年第11期2卷 888-894页

作者： Hala Mohamed Abdel Mageed ahmed faheem zobaa Mohamed Helmy Abdel Raouf Abla Hosni Abd El-Rahman Mohamed Mamdouh Abdel Aziz National Institute for Standards Brunel University

The temperature effects on the electrical performance of a large area multicrystalline silicon solar cell with back-contact technology have been studied in a desert area under ambient conditions using the current shunt measuring technique. Therefore, most of the problems encountered with traditional measuring techniques are avoided. The temperature dependency of the current shunt from 5oC up to 50oC has been investigated. Its temperature coefficient proves to be negligible which means that the temperature dependency of the solar cell is completely independent of the current shunt. The solar module installed in a tilted position at the optimum angle of the location, has been tested in two different seasons (winter and summer). The obtained solar cell short circuit current, open circuit voltage and output power are correlated with the measured incident radiation in both seasons and all results are discussed.

关键词： Large Area Multicrystalline Silicon Solar Cell Current Shunt Measuring Technique Temperature Effects Short Circuit Current Open Circuit Voltage Accumulated Power Incident Radiation

基于CFD的具有首翼的新型飞翔形式AUV升力和阻力估计:对阻力极曲线和推力估计的见解

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哈尔滨工程大学学报（英文版） 2024年第2期23卷 352-365页

作者： faheem ahmed Xianbo Xiang Haotian Wang Gong Xiang Shaolong Yang School of Naval Architecture and Ocean Engineering Huazhong University of Science and Technology1037Luoyu RoadWuhan 430074China State Key Laboratory of Intelligent Manufacturing Equipment and Technology Huazhong University of Science and Technology1037Luoyu RoadWuhan 430074China

To achieve hydrodynamic design excellence in Autonomous Underwater Vehicles(AUVs)largely depends on the accurate prediction of lift and drag *** study presents Computational Fluid Dynamics(CFD)-based lift and drag estimations of a novel torpedo-shaped flight-style AUV with *** horizontal bow-wings are provided to accommodate the electromagnetic arrays used to perform the cable detection and tracking operations near the *** hydrodynamic performance of the AUV due to addition of these horizontal bow-wings is required to be investigated,particularly at the initial design ***,CFD techniques are employed to compute the lift and drag forces observed by the flight-style AUV,maneuvering underwater at different angles of attack and varying *** Reynolds-Averaged Navier-Stokes Equations(RANSE)closure is achieved by employing the modified k-ϵ model and Two-Scale Wall Function(2-SWF)approach is used for boundary layer ***,the study also highlights the unique mesh refinement and solution-adaptive meshing techniques to perform the CFD simulations in Solidworks Flow Simulation(SWFS)*** drag polar curve for flight-style AUV with and without bow-wings is generated using the computed lift and drag *** curve provided essential insights for achieving hydrodynamically efficient and optimized AUV *** the drag polar curve,it is revealed that due to horizontal bow-wings,the flight-style AUV is capable to generate higher lift with less drag and thus,it gives better lift-to-drag ratio compared to the AUV without ***,simulated results of axial drag observed by the AUV have also been compared with free-running experimental results and are found in good agreement.

关键词： Autonomous underwater vehicle(AUV) Computational fluid dynamics(CFD) Solidworks flow simulation(SWFS) Drag polar curve Free-running experiments

Electrochemical performance of a symmetric supercapacitor device designed using laser-induced multilayered graphene

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新型炭材料(中英文) 2024年

作者： Gargi Dhiman Kavita Kumari Bon-Heun Koo faheem ahmed Nagih M.Shaalan Saurabh Dalela Parvez A.Alvi Ranjeet Kumar Brajpuriya Shalendra Kumar Department of Physics School of Advanced EngineeringUPES Industrial Technology Research Institute Changwon National University Changwon Department of Applied Sciences and Humanities Faculty of Engineering and Technology Jamia Millia Islamia Department of Physics College of Science King Faisal University Physics Department Faculty of Science Assiut University Department of Pure & Applied Physics University of Kota Department of Physical Science

This study demonstrates a facile and economical approach for fabricating laser-induced graphene（LIG）, which results in improved electrochemical performance. Polyimide polymer was used as a starting material for LIG synthesis and irradiated under ambient conditions using a CO2laser. The prepared LIG samples were characterized by Raman spectroscopy and FTIR, which validated the formation of multilayered graphene containing sp2 hybridized C=C bonds. The FE-SEM revealed three-dimensional sheetlike structures, while HR-TEM images displayed lattice planes with an interplanar spacing of approximately 0.33 nm, corresponding to the（002） plane of graphene. The electrochemical performance of the as-prepared LIG samples demonstrated a remarkable areal specific capacitance（CA） of 51 mF cm-2(170 F g-1) at 1 mA cm-2(3.3 A g-1) in a three-electrode configuration with 1M KOH as the aqueous electrolyte. The LIG electrodes produced an energy density of ～3.5 μWh cm-2and a power density of ～350 μW cm-2,demonstrating significant energy storage capabilities. Additionally, the electrodes exhibited excellent cyclic stability, retaining 87%of their specific capacitance after 3 000 cycles at 1 mA/cm2. The symmetric supercapacitor fabricated with LIG electrodes and the tested 1M KOH electrolyte showed a specific capacitance of 23 mF cm-2and maintained excellent retention after 10,000 cycles,showing LIG's potential for supercapacitor applications.

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Critical Success Factors to Improve the Game Development Process from a Developer＇s Perspective

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Journal of Computer Science & Technology 2016年第5期31卷 925-950页

作者： Saiqa Aleem Luiz Fernando Capretz faheem ahmed College of Technological Innovation Zayed University Abu Dhabi 144534 United Arab Emirates Department of Electrical and Computer Engineering Western University Ontario N6A 5B9 Canada Department of Computing Science Thompson Rivers University Kamloops BC V2C OC8 Canada

The growth of the software game development industry is enormous and is gaining importance day by day. This growth imposes severe pressure and a number of issues and challenges on the game development community. Game development is a complex process, and one important game development choice is to consider the developer＇s perspective to produce good-quality software games by improving the game development process. The objective of this study is to provide a better understanding of the developer＇s dimension as a factor in software game success. It focuses mainly on an empirical investigation of the effect of key developer＇s factors on the software game development process and eventually on the quality of the resulting game. A quantitative survey was developed and conducted to identify key developer＇s factors for an enhanced game development process. For this study, the developed survey was used to test the research model and hypotheses. The results provide evidence that game development organizations must deal with multiple key factors to remain competitive and to handle high pressure in the software game industry. The main contribution of this paper is to investigate empirically the influence of key developer＇s factors on the game development process.

关键词： developer's perspective software game empirical investigation good-quality game game development process,game developer's factor

Organic additives in all-inorganic perovskite solar cells and modules:from moisture endurance to enhanced efficiency and operational stability

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Journal of Energy Chemistry 2022年第4期31卷 361-390页

作者： Yameen ahmed Bilawal Khan MBilal faheem Keqing Huang Yuanji Gao Junliang Yang State Key Laboratory of Powder Metallurgy School of Physics and ElectronicsCentral South UniversityChangsha 410083HunanChina Department of Materials Science and Engineering City University of HongkongHongkong SAR 999077China Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of ChinaChengdu 610054SichuanChina

Power conversion efficiency(PCE) of perovskite solar cells(PSC) has been skyrocketed to certified 25.5% owing to their improved and tunable optoelectronic properties. Although, various strategies have been adopted to date regarding PCE and stability enhancement within PSC technology, certain instability factors(moisture, heat, light) are hindering their commercial placement. Recently, all-inorganic PSCs got hype in the photovoltaic research community after they attained PCE > 20% and due to their significant endurance against heat and light mishmashes, but there only left moisture sensitivity as the only roadblock for their industrial integration. Here, we review the recent progress of additive inclusion into allinorganic(CsPbX_(3)) PSCs to stabilize their intrinsic structure and to withstand the performance limiting factors. We start with the detailed description of chemical instability of different perovskite compositions, phase segregation, and how organic molecules and dyes help to repair the structural defects to improve the overall PCE and stability of PSCs. Moisture endurance as a result of chemical passivation through organic additives, low-dimensional inorganic PSCs to enhance device stability and scalable fabrication of CsPbX_(3) PSCs are also reviewed. The challenges of module degradation and design implications with proposed strategies and outlook are interpreted in the ending phrases of this review.

关键词： Perovskite solar cells Organic additives Chemical instability Phase segregation Modules

Vegetation-environment relationships in the forests of Chitral district Hindukush range of Pakistan

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Journal of Forestry Research 2013年第2期24卷 205-216页

作者： Nasrullah Khan Syed Shahid Shaukat Moinuddin ahmed Muhammad faheem Siddiqui Department of Botany University of Malakand Dept. of Botany University of Karachi Laboratory of Dendrochronology and Plant Ecology Department of Botany Federal Urdu University of Arts Science and Technology

We investigated the composition of plant communities to quantify their relationships with environmental parameters in the Chitral Hindukush range of Pakistan. We sampled tree vegetation using the Point Centered Quarter （PCQ） method while understory vegetation was sampled in 1.5-m circular quadrats. Cedrus deodara is the national symbol of Pakistan and was dominant in the sampled communities. Because environmental variables determine vegetation types, we analyzed and evaluated edaphic and topographic factors. DCA-Ordination showed the major gradient as an amalgam of elevation （p〈0.05） and slope （p〈0.01） as the topographic factors correlated with species distribution. Soil variables were the factors of environmental significance along DCA axes. However, among these factors, Mg2＋ , K ＋ and N2＋ contributed not more than 0.054% 0.20% and 0.073%, respectively, to variation along the first ordination axis. We conclude that the principal reason for weak or no correlation with many edaphic variables was the anthropogenic disturbance of vegetation. The understory vegetation was composed of perennial herbs in most communities and was most dense under the tree canopy. The understory vegetation strongly regulates tree seedling growth and regeneration patterns. We recommend further study of the understory vegetation using permanent plots to aid development of forest regeneration strategies.

关键词： environmental relationship multivariate analysis cluster analysis ordination anthropogenic factors forest, Hindukush range

Population structure,age and growth rates of conifer species and their relation to environmental variables at Malam Jabba,Swat District,Pakistan

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Journal of Forestry Research 2020年第2期31卷 429-441页

作者： Arsalan Muhammad faheem Siddiqui Moinuddin ahmed Syed Shahid Shaukat Alamdar Hussain Department of Botany University of KarachiKarachi 75270Pakistan Dr.Moinuddin ahmed Laboratory of Plant Ecology and Dendrochronology Department of BotanyFederal Urdu UniversityKarachiPakistan Institute of Environmental Studies University of KarachiKarachiPakistan Department of Botany Karakoram International UniversityGilgitGilgit-BaltistanPakistan

This study focuses on age,growth rate and diameter distribution of pine forests in the Malam Jabba area,Swat District,*** core samples were taken from twenty *** smithiana was the oldest at 234 years with a 112-cm *** pindrow was 125 years with an 80-cm diameter while the oldest Pinus wallichiana was 122 years with 75-cm *** fastest overall growth rate of 1.5±0.1 year/cm was for *** on a west-facing aspect,while the slowest 5.8±2.6 year/cm growth was *** on an eastfacing *** and *** exhibited marked differences in growth rates over a 5-year *** highest growth was by *** from 1966 to *** showed less growth over the same years,such pattern simultaneously reverse from 1911 to *** relationship between diameter and age,diameter and growth rate and age and growth rate were *** and *** ages were correlated with diameter and growth *** age was positive correlated with ***,topographic and edaphic factors did not show significant correlations with growth rates,although some appreciable correlations were *** growth of *** was correlated with elevation while *** was correlated with maximum water retaining *** and age produced uneven size classes and many size gaps,which could be the result of anthropogenic disturbances.

关键词： Dendrochronology Environmental variables Conifer species Forest structure Age classes