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Evaluation of microstructure and mechanical properties of squeeze overcast Al7075-Cu composite joints

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China Foundry 2023年第1期20卷 29-39页

作者： muhammad Waqas Hanif Ahmad Wasim muhammad Sajid Salman Hussain muhammad Jawad Mirza Jahanzaib Department of Industrial Engineering University of Engineering and Technology TaxilaPunjabPakistan

Al7075-Cu composite joints were prepared by the squeeze overcast *** effects of melt temperature,die temperature,and squeeze pressure on hardness and ultimate tensile strength(UTS)of squeeze overcast Al7075-Cu composite joints were *** experimental results depict that squeeze pressure is the most significant process parameter affecting the hardness and *** optimal values of UTS(48 MPa)and hardness(76 HRB)are achieved at a melt temperature of 800℃,a die temperature of 250℃,and a squeeze pressure of 90 *** electron microscopy(SEM)shows that fractured surfaces show flatfaced morphology at the optimal experimental ***-dispersive spectroscopy(EDS)analysis depicts that the atomic weight percentage of Zn decreases with an increase in melt temperature and squeeze *** optimal mechanical properties of the Al7075-Cu overcast joint were achieved at the Al2Cu eutectic phase due to the large number of copper atoms that dispersed into the aluminum melt during the solidification process and the formation of strong intermetallic *** relational analysis integrated with the Taguchi method was used to develop an optimal set of control variables for multi-response parametric *** tests were performed to validate the effectiveness of the employed *** manufacturing of squeeze overcast Al7075-Cu composite joints at optimal process parameters delivers a great indication to acknowledge a new method for foundry practitioners to manufacture materials with superior mechanical properties.

关键词： squeeze overcast joints Al7075-Cu composite joints mechanical properties gray relational analysis Taguchi method

Identification of Anomalous Behavioral Patterns in Crowd Scenes

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Computers, Materials & Continua 2022年第4期71卷 925-939页

作者： muhammad Asif Nauman muhammad Shoaib Department of Computer Engineering University of Engineering and TechnologyLahorePakistan

Real time crowd anomaly detection and analyses has become an active and challenging area of research in computer vision since the last *** emerging need of crowd management and crowd monitoring for public safety has widen the countless paths of deep learning methodologies and ***,researchers have developed many sophisticated algorithms but still it is a challenging and tedious task to manage and monitor crowd in real *** proposed research work focuses on detection of local and global anomaly detection of *** of spatial-temporal features assist in differentiation of feature trained using Mask R-CNN with Resnet101 as a backbone architecture for feature *** data from,BIWI Walking Pedestrian dataset and the Crowds-By-Examples(CBE)dataset and Self-Generated dataset has been used for *** data deals with different situations like one set of data deals with normal situations like people walking and acting individually,in a group or in a dense *** other set of data contains images four unique anomalies like fight,accident,explosion and people behaving *** simulated results show that in terms of precision and recall,our system performs well with Self-Generated ***,our system uses an early stopping mechanism,which allows our system to outperform to make our model *** is why,on 89th epoch our system starts generating finest results.

关键词： Mask R-CNN crowd management and monitoring precision and recall

An integrated land change modeler and distributed hydrological model approach for quantifying future urban runoff dynamics

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Science China Earth Sciences 2024年第10期67卷 3288-3301页

作者： Asad Hussain muhammad Waseem muhammad Ajmal muhammad Atiq Ur Rehman Tariq muhammad Jiaqing XIAO Tao YANG Pengfei SHI Institute for Disaster Risk Management School of Geographical ScienceNanjing University of Information Science and TechnologyNanjing 210044China The National Key Laboratory of Water Disaster Prevention Hohai UniversityNanjing 210098China Yangtze Institute for Conservation and Development Hohai UniversityNanjing 210098China College of Hydrology and Water Resources Hohai UniversityNanjing 210098China Centre of Excellence in Water Resources Engineering University of Engineering and TechnologyLahore 54890Pakistan Department of Agricultural Engineering Faculty of CivilAgricultural and Mining EngineeringUniversity of Engineering and TechnologyPeshawar 25120Pakistan

Climate and land use changes have a significant impact on the runoff generation process in urban environments, and these effects could get worse in the future. The combined contributions of these changes have increased the risk of ***, there is a need for integrated modeling to better understand the runoff variability, especially in small urban catchments. To quantify and separate the effects of land-use changes and climate change on the hydrological response of urban catchments with a distributed hydrological model(Storm Water Management Model, SWMM), this study introduces a new integrated approach based on the Machine Learning based land use change modeler and climate change scenarios under *** on supervised classification and land use change model analysis, accumulated impervious area increase from 22%(in2023) to 33%(in 2060) was observed in the study area. Furthermore, integrating this projected increase in imperviousness with future climate change into SWMM by considering three different scenarios i.e., S1(Climate Change), S2(Combined Land Use and Climate Change), and S3(Land use Change) resulted that climate change could cause an increase in runoff from 13.2% to18.3% in peak runoff and the contribution of land use could range from 9.1% to 18.6%. Similarly, in response to the coupled effects of climate and land-use change, the runoff would likely change from 24.53% to 39.66%. Conclusively, the study showed that despite climate change, intensive urban development by the substitution of impervious surfaces could also have a severe impact on the microclimate and hydrology of small catchments. Lastly, this study could provide a way forward for the future planning and management of water resources in small catchments which could be extended to larger catchments.

关键词： Climate change Land-use modeling Runoff simulation Percent Imperviousness TerrSet

Dynamic flexural strength of Aluminosilicate glass with a perspective of impulsive and quasi-impulsive responses: An experimental-numerical coupled evaluation

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Chinese Journal of Aeronautics 2024年第12期37卷 388-403页

作者： muhammad Aamir RAZA Tao SUO Uzair Ahmed DAR muhammad ATIF muhammad Zakir SHEIKH School of Aeronautics and Institute of Extreme Mechanics Northwestern Polytechnical UniversityXi’an 710072China Joint International Research Center of Impact Dynamics and Its Engineering Application Northwestern Polytechnical UniversityXi’an 710072China Shaanxi Key Laboratory of Impact Dynamics and Engineering Application Northwestern Polytechnical UniversityXi’an 710072China National Key Laboratory of Strength and Structural Integrity Northwestern Polytechnical UniversityXi’an 710072China

The flexural strength of glass is a critical design parameter for applications encountering impact ***,the micro defects,specimen geometry,loading rate,and load transformation from a quasi-dynamic to quasi-impulsive state may influence the measurement *** to the stochastic and amorphous nature of the material,an accurate determination of the flexural strength remains a *** this two-fold study,a coupled experimental-numerical strategy was devised to evaluate the dynamic flexural *** the first phase,three-point bending experiments were conducted on a novel“Electromagnetic Split Hopkinson Pressure Bar(ESHPB)”.The incident stress signal and fracture time were recorded from experimental data,while the flexural strength was indirectly computed from a numerical algorithm.A quantitative comparison of the flexural strength with those in existing literature established the accuracy of the proposed *** of the study indicate that the specimen response became independent of the support conditions under impulsive *** being said,the specimen behaved like it had an infinite span length,and the measured flexural strength remained the same whether the specimen was supported or ***,the specimen also maintained contact at the interfaces of the incident bar and fixture supports for the entire loading *** the second part of this study,the computed flexural strength was used to calibrate the existing JH-2 *** prediction of the damage propagation corroborated with that obtained from reprography images,though *** work presents a precise and robust methodology to determine the dynamic flexural strength of brittle ceramics like Aluminosilicate glass over traditional experimental procedures to facilitate its adoption.

关键词： Dynamic flexural strength Damage mechanism Flexural fracture Numerical simulation Aluminosilicate glass

Structural,electronic,and magnetic behaviors of 5d transition metal atom substituted divacancy graphene：A first-principles study

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Chinese Physics B 2017年第5期26卷 304-312页

作者： Rafique muhammad 帅永 He-Ping Tan Hassan muhammad School of Energy Science and Engineering Harbin Institute of Technology Harbin 150001 China Mehran University of Engineering and Technology S.Z.A.B Campus Khairpur Mir' s Sindh Pakistan

Structural, electronic, and magnetic behaviors of 5d transition metal（TM） atom substituted divacancy（DV） graphene are investigated using first-principles calculations. Different 5d TM atoms（Hf, Ta, W, Re, Os, Ir, and Pt） are embedded in graphene, these impurity atoms replace 2 carbon atoms in the graphene sheet. It is revealed that the charge transfer occurs from 5d TM atoms to the graphene layer. Hf, Ta, and W substituted graphene structures exhibit a finite band gap at high symmetric K-point in their spin up and spin down channels with 0.783 μB, 1.65 μB, and 1.78 μB magnetic moments,respectively. Ir and Pt substituted graphene structures display indirect band gap semiconductor behavior. Interestingly, Os substituted graphene shows direct band gap semiconductor behavior having a band gap of approximately 0.4 e V in their spin up channel with 1.5 μB magnetic moment. Through density of states（DOS） analysis, we can predict that d orbitals of 5d TM atoms could be responsible for introducing ferromagnetism in the graphene layer. We believe that our obtained results provide a new route for potential applications of dilute magnetic semiconductors and half-metals in spintronic devices by employing 5d transition metal atom-doped graphene complexes.

关键词： substituted impurity symmetric dilute complexes monolayer Fermi replace polarized doping

Optimization Based on Convergence Velocity and Reliability for Hydraulic Servo System

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Chinese Journal of Aeronautics 2009年第4期22卷 407-412页

作者： muhammad Babar Nazir School of Automation Science and Electrical Engineering Beijing University of Aeronautics and Astronautics

This article presents an optimal hybrid fuzzy proportion integral derivative （HFPID） controller based on combination of proportion integral derivative （PID） and fuzzy controllers, by which the parameters could be evaluated by global optimization either in convergence velocity or in convergence reliability. Focusing on the nonlinear factors of hydraulic servo system, this article takes advantage of PID and fuzzy logic controller integrated with scaling factors to acquire precise tracking performances. To further improve the performances, it provides new developed optimization with rapid convergence to attain reliable approach probability. Focusing on the performance indictors of evolutionary algorithm, this article presents a new technique to predict reliability of the optimization algorithm. Statistics authenticates the effectiveness and robustness of the optimization. Further, many simulation and experimental results indicate that the optimal HFPID could acquire perfect immunity against parametric uncertainties with external disturbance.

关键词： adaptive control system novel evolutionary algorithm hydraulic control equipment convergence velocity convergencereliability optimization

Efect of Thermal Annealing on the Physical Properties of Zn_(1-x)Cu_xSe Thin Films Deposited by Close Spaced Sublimation Technique

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Acta Metallurgica Sinica(English Letters) 2013年第6期26卷 699-706页

作者： muhammad Arslan Riaz muhammad Arshad Mahmood Rashad Rasheed Department of Applied Physics Federal Urdu University of ArtsSciences and Technology National Institute of Lasers and Optronics

Thin films of Zn1-xCuxSe （x= 0.00, 0.05, 0.10, 0.15, 0.20） were grown on glass substrates by closed space sublimation technique. The deposited films were annealed at 200 ~C and 400 ~C in air for 1 h. The annealed samples have been investigated through Rutherford backscattering spectroscopy （RBS）, X-ray diffraction （XRD）, spectroscopic ellipsometer, spectrophotometer and Raman spectroscopy. Through RBS, the composition of the films was calculated and compared with the initial concentration. Structural characteriza- tion including crystal structure, crystal orientation, lattice parameter, grain size, strain and dislocation density were carried out using XRD data. From XRD spectra it was revealed that the as-deposited and annealed films were polycrystalline in nature with zinc-blende structure. However, the crystallinity and the grain size were improved with the increase of annealing temperature. According to Raman spectroscopy, it was observed that as deposited and annealed samples have the same characteristic vibrational modes of ZnSe at low and high frequency optical phonon modes while another mode was observed for 400 ℃ annealed samples at 745 cm-1. Spectroscopic ellipsometer has been used to found annealing effect on the optical properties of ZnSe. The band gap energy has been determined using transmission spectra. It was found that the band gap energy of the film increased with the increase of annealing temperature.

关键词： Closed space sublimation Annealing effect Structural Transmission Band gap Spectroscopic ellipsometer Raman spectroscopy

Order selection in fractional Fourier transform based beamforming

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Journal of Systems Engineering and Electronics 2010年第3期21卷 361-369页

作者： muhammad Ishtiaq Ahmad School of Information and Electronics Beijing Institute of Technology

Traditionally,beamforming using fractional Fourier transform（FrFT） involves a trial-and-error based FrFT order selection which is impractical.A new numerical order selection scheme is presented based on fractional power spectra（FrFT moment） of the linear chirp *** method can adaptively determine the optimum FrFT order by maximizing the second-order central FrFT *** makes the desired chirp signal substantially concentrated whereas the noise is rejected *** improves the mean square error minimization beamformer by reducing effectively the signal-noise cross terms due to the finite data length de-correlation *** results show that the new method works well under a wide range of signal to noise ratio and signal to interference ratio.

关键词： adaptive beamforming fractional Fourier transform (FrFT) fractional moments chirp signal.

Surface modification techniques of membranes to improve their antifouling characteristics:recent advancements and developments

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Frontiers of Chemical Science and Engineering 2023年第12期17卷 1837-1865页

作者： muhammad Tawalbeh Haya Aljaghoub muhammad Qasim Amani Al-Othman Sustainable and Renewable Energy Engineering Department University of SharjahSharjah 27272United Arab Emirates Sustainable Energy&Power Systems Research Centre RISEUniversity of SharjahSharjah 27272United Arab Emirates Industrial Engineering and Engineering Management Department University of SharjahSharjah 27272United Arab Emirates Department of Chemical and Biological Engineering American University of SharjahSharjah 26666United Arab Emirates Materials Science and Engineering Program College of Arts and SciencesAmerican University of SharjahSharjah 26666United Arab Emirates

Extensive research efforts are currently devoted to developing and improving conventional technologies for water treatment. Membrane-based water treatment technologies are among the most preferred options due to their commercial success, simple operation, low energy and space requirements, and high separation efficiency. Despite the advances made in membrane-based technologies, fouling remains a critical challenge. Fouling occurs upon the accumulation of unwanted impurities on the membrane surface and within the membrane pores which results in a significant decline in the membrane permeate flux. To alleviate the operational challenges from fouling, surface modification to develop antifouling membranes appears to be an effective technique. A comprehensive review of the surface modification techniques for the development of antifouling membranes is provided in this paper. Chemical surface modification techniques (grafting and plasma treatment), physical modification techniques (blending, coating, adsorption, and thermal treatment), and combined physical and chemical modification techniques have been discussed. Moreover, the challenges related to surface modification and the future research directions are addressed.

关键词： fouling antifouling membrane surface modification membrane pretreatment