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Chinese Journal of Mechanical Engineering 2006年第3期19卷 159-167页

作者： ahmed n.a School of Mechanical and Manufacturing Engineering University of new South Wales Sydney 2052 Australia

A comprehensive hot wire investigation of the flow around a circular cylinder is carried out in.an 18＂ × 18＂ wind tunnel to look into the dominant frequencies at the stagnation, separation.and separated shear layers in the transition Reynolds number range. The majority of the experiments are carried out at Reynolds number of 4.5×104, with additional transition frequency tests at Reynolds numbers of 2.9×104, 3.3×104 and 9.7×104 respectively. The results are analysed in terms of power spectral density. While the frequency associated with stagnation is found to be essentially due to vortex shedding, frequency doubling of vortex shedding is also evident in the separated shear layers. Two peaks associated with transition frequencies are detected and their possible implications are presented.

关键词： Vortex shedding Transition Separated flow Power spectral density

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EDSUCh:A robust ensemble data summarization method for effective medical diagnosis

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Digital Communications and networks 2024年第1期10卷 182-189页

作者： Mohiuddin ahmed A.n.M.Bazlur Rashid School of Science Edith Cowan UniversityPerthAustralia

Identifying rare patterns for medical diagnosis is a challenging task due to heterogeneity and the volume of *** summarization can create a concise version of the original data that can be used for effective *** this paper,we propose an ensemble summarization method that combines clustering and sampling to create a summary of the original data to ensure the inclusion of rare *** the best of our knowledge,there has been no such technique available to augment the performance of anomaly detection techniques and simultaneously increase the efficiency of medical *** performance of popular anomaly detection.algorithms increases significantly in terms of accuracy and computational complexity when the summaries are ***,the medical diagnosis becomes more effective,and our experimen.al results reflect that the combination of the proposed summarization scheme and all underlying algorithms used in this paper outperforms the most popular anomaly detection techniques.

关键词： Data summarization Ensemble Medical diagnosis Sampling

Effect of insoluble materials on the volumetric behavior of rock salt

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第1期13卷 84-97页

作者： Mejda Azabou ahmed Rouabhi Laura Blanco-Martìn MInES ParisTech PSL Research UniversityCentre de Géosciences35 rue St HonoréFontainebleau77300France

This paper focuses on the presence of nodules of insoluble materials within salt specimens,and their effect on the volumetric strain measurements and the dilatancy *** analyzed experimen.al results of over 120 conventional triaxial compression tests,and found that in 20%of the cases,the volumetric strain measurements were *** also noted that the natural variability of the specimens can lead to a non-negligible data scattering in the volumetric strain measurements when different specimens are subjected to the same *** is expected given the small magnitude of those strains,but it occasionally implies that the corresponding specimens are not represen.ative of the volumetric behavior of the studied *** order to understand these results,we numerically investigated salt specimens modeled as halite matrices with inclusions of *** of triaxial compression tests on these structures proved that such heterogeneities can induce dilatancy,and their presence can lead to the appearance of tensile zones which is physically translated into a micro-cracking *** modeling approach is validated as the patterns displayed in the numerical results are identical to that in the *** was then employed to explain the observed irregularities in experimen.al *** studied the natural variability effect as well and proposed a methodology to overcome the issue of specimen represen.ativity from both deviatoric and volumetric perspectives.

关键词： Rock salt Dilatancy Material heterogeneity natural variability Triaxial tests Virtual laboratory

Influence of biomass density and food to microorganisms ratio on the mixed culture type I methanotrophs enriched from activated sludge

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Journal of Environmen.al Sciences 2018年第8期30卷 87-96页

作者： ahmed AlSayed ahmed Fergala ahmed Eldyasti Department of Civil Engineering Lassonde School of Engineering York University

Methanotrophic based process can be the remedy to offset the wastewater treatment facilities increasing energy requirements due to methanotroph＇s unique ability to integrate methane assimilation with multiple biotechnological applications like biological nitrogen removal and methanol production. Regardless of the methanotrophic process end product, the challenge to main.ain stable microbial growth in the methanotrophs cultivation bioreactor at higher cell densities is one of the major obstacles facing the process upscaling. Therefore, a series of consecutive batch tests were performed to attentively investigate the biomass density influence on type I methanotrophs bacterial growth. In.addition, food to microorganisms（F/M）, carbon to nitrogen（C/n） and nitrogen to microorganisms（n/M） ratio effect on the microbial activity was studied for the first time. It was clarified that the F/M ratio is the most influencing factor on the microbial growth at higher biomass densities rather than the biomass density increase, whereas C/n.and n/M ratio change, while using nitrate as the nitrogen source,does not influence methanotrophs microbial growth. These study results would facilitate the scaling up of methanotrophic based biotechnology by identifying that F/M ratio as the key parameter that influences methanotrophs cultivation.at high biomass densities.

关键词： Methanotrophs Wastewater treatment Food to microorganisms ratio Biomass density

A Review on Primary and Secon.ary Controls of Inverter-interfaced Microgrid

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Journal of Modern Power Systems and Clean Energy 2021年第5期9卷 969-985页

作者： Kafeel ahmed Mehdi Seyedmahmoudian Saad Mekhilef n.M.Mubarak Alex Stojcevski School of Software and Electrical Engineering Swinburne University of TechnologyVIC 3122VictoriaAustralia Power Electronics and Renewable Energy Research Laboratory Department of Electrical EngineeringUniversity of Malaya50603 Kuala LumpurMalaysia Department of Chemical Engineering Faculty of Engineering and ScienceCurtin University of Technology98009 SarawakMalaysia

The demand of electricity and environmen.al issues associated with conventional power generation plants are increasing *** technology has transformed the conventional power system through the integration of distributed generation(DG).With the help of modern power electronic technology,the conventional power system is able to support the integration of DGs based on renewable energy sources(RESs).The systematic combination of DGs with energy storage system forms a microgrid(MG),which can operate in islanded mode or grid-connected *** intermittent nature of RES and varying load pose substantial obstacles such as voltage and frequency instability,and the unreliability of *** feeder impedances and non-lin.ar loads are considered as present challenges in MG *** control has been useful in undertaking solutions to these *** paper covers the deep insight of different control methods applied at the primary and secon.ary control levels in hierarchical *** primary control,the classification based on droop and non-droop controls is *** virtual synchronization machine(VSM)based control method is *** and frequency restoration control and economical operations at decentralized and centralized secon.ary control are analyzed in *** on the existing literature,critical discussion on MG control and future trends are also presented to provide future research perspectives.

关键词： Distributed generation(DG) hierarchical control droop control non-droop control inverter

Effectiveness of external prestressing in en.ancing the non-ductile hanger failure mechanism in reinforced concrete inverted T-beams

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Frontiers of Structural and Civil Engineering 2024年第7期18卷 1050-1065页

作者： ahmed M.ATTA Reda n.BEHIRY Mohammed I.HARAZ Structural Engineering Department Faculty of EngineeringTanta UniversityTanta 33511Egypt nile Higher Institute for Engineering and Technology Mansoura 11001Egypt

Recently,inverted T-beams have been used in reinforced concrete(RC)bridges to support transverse precast *** T-beams,contrary to practice with conventional beams,are loaded on the flanges upper *** loading configuration causes hanger failure due to the generation of vertical tensile stresses n.ar the bottom of the *** key purpose of this study is to investigate the efficiency of vertical external prestressing stainless-steel bars in mitigating non-ductile hanger failure in reinforced concrete inverted *** experimen.al study on six inverted-T beams,including two un-strengthened specimens,was carried *** study showed that the value of the prestressing level had a considerable impact on the performance of hanger mechanism in relation to crack pattern,ultimate loads,cracking behavior,load-deflection,strains,and *** experimen.al results indicated that the suggested method for strengthening inverted T-beams had efficacy in reducing the seriousness of the non-ductile hanger failure and resulted in.a strength increase of up to 53% when compared to that of the un-strengthened ***,two analytical models for estimating the hanger capacity and the average crack width of the strengthened RC inverted T-beams were *** models that were proposed exhibited a high degree of agreement with the experimen.al results.

关键词： RC bridges inverted T-beams strengthening hanger failure external prestressing

Antioxidant and anti-glycation.activities correlates with phenolic composition of tropical medicinal herbs

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Asian Pacific Journal of Tropical Medicine 2013年第7期6卷 561-569页

作者： JS Ramkissoon MF Mahomoodally n ahmed AH Subratty Department of Health Sciences Faculty of ScienceUniversity of MauritiusReduitMauritius School of Healthcare Science Manchester Metropolitan UniversityManchesterUnited Kingdom Department of Health Sciences Faculty of ScienceUniversity of Mauritius.ReduitMauritius

To determine the contribution of total phenolic content(TPC) in glycation inhibitory activity of common tropical medicinal food and spices with potential antioxidative properties. Methods:In vitro glucose-bovine serum albumin(BSA) assay was *** extracts of ten common household condiments/herbs(Allium *** *** rulgaris, Petroselinum crispum,Murraya koenigii Spreng,Mentha piperita L.,Curcuma lon.a L.,Allium cepa L.,Allium fistulosum and Coriandrum sativum L.) were evaluated for antinxidative activity by 2,2-diphenyl-2-picrylhydrazyl(DPPH),and ferric reducing antioxidant power(FRAP) and the *** and tannins content were ***:Findings showed good correlation between TPC/DPPH(r= 0.8).TPC/FRAP(r= 0.8).TPC/Anti-glycation(r=0.9).DPPH/Anti-glycation (r= 0.6),FRAP/Anti-glycation(r = 0.9),Flavonoid/Anti-glycation(r=0.7) and Tannina/Antiglycation (r = 0.8) and relatively fair correlation for TPC/Flavonoids(r = 0.5) and TPC/Tannina(r = 0.5).Results imply that these plants are potential sources of natural antioxidants which have free radical scavenging activity and might be used for reducing oxidative ***:The positive glycation inhibitory and antioxidative activities of these tropical herbs suggest a possible role in targeting ageing,diabetic complications and oxidative stress related diseases.

关键词： Food plants Anti-glycation AGEs Antioxidants TPC DPPH FRAP

Energy Management Control StraEnergy Management Control Strategy for Renewable Energy System Based on Spotted Hyena Optimizertegy for Renewable Energy System Based on Spotted Hyena Optimizer

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Computers, Materials & Contin.a 2021年第5期67卷 2271-2281页

作者： Hegazy Rezk ahmed Fathy Mokhtar Aly Mohamed n.Ibrahim College of Engineering at Wadi Addawaser Prince Sattam Bin Abdulaziz UniversityWadi Addawaser11991Saudi Arabia Electrical Engineering Department Faculty of EngineeringMinia UniversityMinia61111Egypt Electrical Engineering Department Faculty of EngineeringJouf UniversitySakakaSaudi Arabia Electrical Power and Machine Department Faculty of EngineeringZagazig UniversityZagazigEgypt Department of Electrical Engineering Aswan UniversityAswan81542Egypt Electronics Engineering Department Universidad Tecnica Federico Santa MariaValparaiso2390123Chile Department of Electromechanical Systems and Metal EngineeringGhent UniversityGhent9000Belgium FlandersMake@UGent–corelab EEDT-MP 3001LeuvenBelgium Electrical Engineering Department Kafrelshiekh UniversityKafr el-Sheikh33511Egypt

Hydrocarbons,carbon monoxide and other pollutants from the transportation sector harm human health in many *** cell(FC)has been evolving rapidly over the past two decades due to its efficient mechanism to transform the chemical energy in hydrogen-rich compounds into electrical *** main drawback of the stan.alone FC is its slow dynamic response and its inability to supply rapid variations in the load ***,adding energy storage systems is ***,to manage and distribute the power-sharing among the hybrid proton exchange membrane(PEM)fuel cell(FC),battery storage(BS),and supercapacitor(SC),an energy management strategy(EMS)is *** this research work,an optimal EMS based on.a spotted hyena optimizer(SHO)for hybrid PEM fuel cell/BS/SC is *** main goal of an EMS is to improve the performance of hybrid FC/BS/SC and to reduce the amount of hydrogen *** prove the superiority of the SHO method,the obtained results are compared with the chimp optimizer(CO),the artificial ecosystem-based optimizer(AEO),the seagull optimization.algorithm(SOA),the sooty tern optimization.algorithm(STOA),and the coyote optimization.algorithm(COA).Two main metrics are used as a benchmark for the comparison:the minimum consumed hydrogen.and the efficiency of the *** main findings confirm that the minimum amount of hydrogen consumption.and maximum efficiency are achieved by the proposed SHO based EMS.

关键词： Modelling optimization energy management fuel cell supercapacitor hybrid system

Phase analysis of AlFe2B2 by synchrotron X-ray diffraction,magnetic and M?ssbauer studies

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Progress in natural Science:Materials International 2017年第2期27卷 251-256页

作者： Tahir Ali M.n.Khan E.ahmed Asad Ali Physics Division Pakistan Institute of Nuclear Science and technology Department of Physics Abdul Wali Khan University PIn.aT Preston University

The structural and magnetic properties of essentially phase pure AlFe2B2prepared by arc melting were compared with a sample con.aining impurities. Analysis was carried out by means of synchrotron X-ray diffraction, magnetic measurements and M?ssbauer spectroscopy. The analysis of synchrotron X-ray diffraction data confirmed the orthorhombic structure of space group Cmmm for AlFe2B2with Al13Fe4as main impurity phase. The magnetic measurements revealed an un.aturated ferromagnetic state in.alFe2B2with a transition temperature（Tc） of 286 K. Isothermal magnetization measurment at 5 K gave a saturation magnetization of 0.7 μB per Fe atom while Arrott plots establish the second order nature of ferromagnetic transition. The thermal evolution of M?ssbauer spectra confirmed the ferromagnetic nature of this material revealing an hyperfine field of 73 kOe and an isomer shift of 0.46 mm/s at 100 K. The M?ssbauer spectra of a phase pure sample was compared with the one con.aining impurity phases. It is suggested that the low temperature paramagnetic contribution in M?ssbauer spectra of phase pure material may have its origin in some intrinsic phenomena arising from defects or inhomogeneities in crystal structure.

关键词： AlFe2B2 Synchrotron X-ray diffraction Ferromagnetism Mossbauer effect spectroscopy

A Fuzzy Logic Based Power-Efficient Run-Time Reconfigurable Multicore System

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Chinese Journal of Electronics 2018年第3期27卷 549-555页

作者： Shaheryar najam Muhammad Yasir Qadri Zohaib najam Jameel ahmed nadia n.Qadri Electrical Engineering Department Riphah International University School of Computer Science and Electronic Engineering University of Essex Electrical Engineering Department HITEC University Department of Electrical Engineering COMSATS Institute of Information Technology

Increasing demand for better throughput and performance has motivated designers to come up with more sophisticated processors with innovative designs. Such designs for multicore architectures offer large amount of parallelism which is often underutilized and thus becomes overhead and liability. Due to these advancements, there has been.a exponential increase in power consumption.and heat dissipation of computing devices. Under these circumstances, an ideal system would be a reconfigurable system that can switch off all underutilized resources and work with only required ones. There is a need of reconfigurable computing devices and processors that are smart enough to configure themselves dynamically on runtime to find balance between throughput and power-consumption. This paper proposes a novel fuzzy logic based Dynamic voltage and frequency scaling(DVFS)and power-gating enabled controller which is capable of reducing power-consumption without affecting throughput and overall performance of the system. The design is implemented on Intel processor using Ubuntu as an operating system. Implemen.ation results show that proposed Fuzzy logic controller(FLC) reduces power-consumption upto 40% by reconfiguring the processor dynamically without compromising the throughput.

关键词： DVFS Fuzzy logic controller Energy Throughput