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Finite element analysis of dynamic stability of skeletal structures under periodic loading

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第2期8卷 245-256页

作者： THANA Hemantha Kumar AMEEN mohammed Department of Civil Engineering National Institute of Technology Calicut Kerala 673601 India

This paper addresses the dynamic stability problem of columns and frames subjected to axially applied periodic loads. Such a structure can become unstable under certain combinations of amplitudes and frequencies of the imposed load acting on its columns/beams. These are usually shown in the form of plots which describe regions of instability. The finite element method (FEM) is used in this work to analyse dynamic stability problems of columns. Two-noded beam elements are used for this purpose. The periodic loading is decomposed into various harmonics using Fourier series expansion. Computer codes in C++ using object oriented concepts are developed to determine the stability regions of columns subjected to periodic loading. A number of nu-merical examples are presented to illustrate the working of the program. The direct integration of the equations of motions of the discretised system is carried out using Newmark’s method to verify the results.

关键词： Finite element analysis Dynamic stability Mathieu-Hill equation

Comparative study of abrasion via microindentation and microscratch tests of reinforced and unreinforced lamellar cast iron

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Friction 2019年第5期7卷 457-465页

作者： mohammed MENDAS Stéphane BENAYOUN Laboratory of Rheology and Mechanics(LRM) Hassiba Benbouali University of ChlefHay Essalem Chlef BP151(02000)Algeria LTDS UMR CNRS5513Ecole Centrale de LyonUniversity of LyonEcully Cedex F-69134France

This study compares micro-abrasive wear in two kinds of grey cast iron. Classical lamellar cast iron with fully pearlitic matrix(FGL1) and lamellar micro-alloyed cast iron with phosphorus and boron(FGL2) are used. FGL2 has a fully pearlitic matrix reinforced by the hard phosphorus eutectic phase. The microstructures of these two types of iron are mechanically characterized using nanoindentation tests. Vickers microindentation and microscratch tests are also performed on these iron samples. The indent and scratch images obtained via scanning electron microscopy were used to compare the scratch damage to the two kinds of iron. The friction coefficient is discussed in terms of applied load, indenter attack angle, and scratch damage. Nanoindentation tests show an improvement in graphite’s mechanical properties and an increase in the matrix hardness of the FGL2, relatively to FGL1. The same damage forms for both microindentation and microscratch testing were observed for the two iron samples. However, cracking of the hard phase is observed in FGL2. The results show that the scratching of the micro-alloyed iron(FGL2) leads to less matrix damage and to an extended microploughing wear mechanism. However, at low normal load, the reinforcement of the matrix can increase the friction coefficient.

关键词： grey cast iron indentation microscratch abrasive wear

Biopolymers and Biomimetic Materials in Medical and Electronic-Related Applications for Environment-Health-Development Nexus:Systematic Review

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Journal of Bionic Engineering 2022年第6期19卷 1562-1577页

作者： Faris mohammed AL-Oqla mohammed Hassouna Alaaeddin Muhammad Enamul Hoque Vijay Kumar Thakur Department of Mechanical Engineering Faculty of EngineeringThe Hashemite UniversityP.O Box 330127Zarqa13133Jordan University College Fairview 2AJalan TP2Sime UEP Industrial Park Subang Jaya47600Subang JayaSelangorMalaysia Department of Biomedical Engineering Military Institute of Science and Technology(MIST)Mirpur CantonmentDhaka1216Bangladesh Biorefining and Advanced Materials Research Center Scotland’s Rural College(SRUC)Kings BuildingsEdinburghEH93JGUK School of Engineering University of Petroleum&Energy Studies(UPES)Dehradun248007UttarakhandIndia

Biocomposites as bio-inspired materials are produced from renewable resources that are organic and ecofriendly alternative *** improve the lifestyle of human beings as well as enhancing the environmental indices,functional bio-materials are now implemented in various promising *** work has systematically discussed and highlighted the implementations and trends of functional bionic materials in high tech industries,which are necessary for developing modern *** medical,electronic,food and pharmaceutical applications have been ***-inspired materials are used to develop more sustainable possibilities to increase environmental conservation while maintaining customer *** were found employed in several sectors for various functional bio-products including organic thin-film transistors,organic phototransistor,emitting diodes,photodiodes,photovoltaic solar cells,hybrid dental resins,sustainable pharmaceuticals,and food *** are used to create sustainable bio-products for energy storage and harvesting,bone regeneration,nerve damage repair,drug applications and various other industrial subcategories.

关键词： Biopolymers Bioinspired Biomimetic materials Tissue engineering Nerve repair Organic transistors

Hybrid meta-heuristic machine learning methods applied to landslide susceptibility mapping in the Sahel-Algiers

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International Journal of Sediment Research 2022年第5期37卷 601-618页

作者： mohammed Amin Benbouras Technology Department Ecole Normale Sup erieure D?Enseignement Technologique de Skikda (ENSET) Laboratoire Central des Travaux Publics (LCTP)

Landslides are considered as one among many phenomena jeopardizing human beings as well as their constructions. To prevent this disastrous problem, researchers have used several approaches for landslide susceptibility modeling, for the purpose of preparing accurate maps marking landslide prone *** the most frequently used approaches for landslide susceptibility mapping is the Artificial Neural Network(ANN) method. However, the effectiveness of ANN methods could be enhanced by using hybrid metaheuristic algorithms, which are scarcely applied in landslide mapping. In the current study, nine hybrid metaheuristic algorithms, genetic algorithm(GA)-ANN, evolutionary strategy(ES)-ANN, ant colony optimization(ACO)-ANN, particle swarm optimization(PSO)-ANN, biogeography based optimization(BBO)-ANN, gravitational search algorithm(GHA)-ANN, particle swarm optimization and gravitational search algorithm(PSOGSA)-ANN, grey wolves optimization(GWO)-ANN, and probability based incremental learning(PBIL)-ANN have been used to spatially predict landslide susceptibility in Algiers’ Sahel,Algeria. The modeling phase was done using a database of 78 landslides collected utilizing Google Earth images, field surveys, and six conditioning factors(lithology, elevation, slope, land cover, distance to stream, and distance to road). Initially, a gamma test was used to decrease the input variable ***, the optimal inputs have been modeled by the mean of hybrid metaheuristic ANN techniques and their performance was assessed through seven statistical indicators. The comparative study proves the effectiveness of the co-evolutionary PSOGSA-ANN model, which yielded higher performance in predicting landslide susceptibility compared to the other models. Sensitivity analysis using the stepby-step technique was done afterward, which revealed that the distance to the stream is the most influential factor on landslide susceptibility, followed by the slope factor which ranked second. L

关键词： Artificial neural network Hybrid metaheuristic optimization algorithms Landslide susceptibility Geographical information system Sensitivity analysis

Stability of Three-Dimensional Interfacial Waves Under Subharmonic Disturbances

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China Ocean Engineering 2023年第4期37卷 558-567页

作者： Nabil ALLALOU mohammed DEBIANE Christian KHARIF Facultéde Physique Universitédes Sciences et de la Technologie Houari Boumediene(USTHB)Algiers 16123Algeria Technopole de Chateau-Gombert Institut de Recherche sur les Phénomènes Hors Equilibre(IRPHE)Marseille 13384France

This study examines the stability regimes of three-dimensional interfacial gravity *** numerical results of the linear stability analysis extend the three-dimensional surface waves results of Ioualalen and Kharif(1994)to three-dimensional interfacial *** approach of the collocation type has been developed for this *** equations of motion are reduced to an eigenvalue problem where the perturbations are spectrally decomposed into normal *** results obtained showed that the density ratio plays a stabilizing *** addition,the dominant instability is of three-dimensional structure,and it belongs to class I for all values of density ratio.

关键词： short-crested interfacial waves linear stability collocation method Padéapproximant

Role of dissolved oxygen reduction in improvement inhibition performance of ascorbic acid during copper corrosion in 0.50 mol/L sulphuric acid

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Chinese Chemical Letters 2010年第3期21卷 341-345页

作者： mohammed A.Amin Chemistry Department Faculty of ScienceAin Shams University

The kinetics of dissolved O_2 reduction and hydrogen evolution reactions on copper surface was studied in naturally aerated and air and O_2-saturated 0.50 mol/L H_2SO_4 solutions using polarization measurements combined with the rotating disc electrode (RDE).The Koutecky-Levich plot indicated that the dissolved O_2 reduction at the copper electrode was an apparent four-electron process.A correlation between the presence of dissolved O_2 and the formation of Cu_2O,confirmed from XRD,was discussed. Ascorbic a...

关键词： Copper Sulphuric acid solutions Corrosion inhibition Ascorbic acid RDE O_2 reduction

Numerical evaluation of enhanced green infrastructures for mitigating urban heat in a desert urban setting

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Building Simulation 2023年第9期16卷 1691-1712页

作者： Afifa mohammed Ansar Khan Mattheos Santamouris Faculty of Built Environment University of New South WalesSydneyAustralia Department of Geography Lalbaba CollegeUniversity of CalcuttaKolkataIndia

The cities of desert climates are anticipated to recognize a synergy of urban heat island(UHI)and severe heat waves during *** improve the urban thermal environment,the present study aims quantitatively explore a strategically designed network of vegetation patches called green infrastructure(GI)in subtropical desert cities such as *** achieve a more comfortable temperature environment,we built and simulated four GI situations with higher GI fractions,GI25,GI50,GI75,and *** a mesoscale urban model,the mosaic approach is utilized to test potential thermal improvement and urban climate impact,and a portion of each urban grid cell in the model domain is altered with various species of urban vegetation patches by 25%,50%,75%,and 100%.The daily peak reduction in ambient temperature at 17:00LT is similar to 0.0168℃ per unit of GI increase when compared to the untreated scenario;however,the maximum anticipated daytime summer temperature decline for GI25,GI50,GI75,and GI100 is 0.6℃,1.1℃,1.4℃,and 1.7℃,*** associated reduction in nighttime ambient temperature per unit increase in the GI is 0.0432℃,with a maximum temperature drop of around 2.4℃ for the GI100 *** GI reduces the height of the planetary boundary layer(PBL)by up to 468 m,which might lead to greater pollution *** GI-based cooling has a significant influence on delayed sea breeze and humidity,it may raise the risk of heat discomfort in the indoor building *** study adds to our understanding of the potential for GI mitigation as well as the seasonal impact of developing GIs on the desert urban boundary layer.

关键词： green infrastructure heat mitigation urban heat WRF-SLUCM Dubai city

Hepatoprotective activity of Sapindus mukorossi and Rheum emodi extracts: In vitro and in vivo studies

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World Journal of Gastroenterology 2008年第16期14卷 2566-2571页

作者： mohammed Ibrahim mohammed Nane Khaja Anjum Aara Aleem Ahmed Khan mohammed Aejaz Habeeb Yalavarthy Prameela Devi Mangamoori Lakshmi Narasu Chitoor mohammed Habibullah Centre for Liver Research and Diagnostics Deccan college of Medical Sciences and Allied Hospitals Kanchanbagh Nizam Institute of Pharmacy Deshmukhi pochampally (Mandal) Near Ramoji Film City Centre for Biotechnology Jawaharlal Nehru Technological University Kukatpally

AIM: To study the hepatoprotective capacity of Sapindus mukorossi (S. mukorossi) and Rheum emodi (R. emodi) extracts in CCl4 treated male rats. METHODS: The dried powder of S. mukorossi and R. emodi was extracted successively with petroleum ether, benzene, chloroform, and ethanol and concentrated in vacuum. Primary rat hepatocyte monolayer cultures were used for in vitro studies. In vivo, the hepatoprotective capacity of the extract of the fruit pericarp of S. mukorossi and the rhizomes of R. emodi was analyzed in liver injured CCl4-treated male rats. RESULTS: In vitro: primary hepatocytes monolayer cultures were treated with CCl4 and extracts of S. mukorossi & R. emodi. A protective activity could be demonstrated in the CCl4 damaged primary monolayer culture. In vivo : extracts of the fruit pericarp of S. mukorossi (2.5 mg/mL) and rhizomes of R. emodi (3.0 mg/mL) were found to have protective properties in rats with CCl4 induced liver damage as judged from serum marker enzyme activities. CONCLUSION: The extracts of S. mukorossi and R. emodi do have a protective capacity both in vitro on primary hepatocytes cultures and in in vivo in a rat model of CCl4 mediated liver injury.

关键词： Hepatoprotective activity Sapindus mukorossr Rheum emodi

Cellular therapy:A promising tool in the future of colorectal surgery

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World Journal of Gastroenterology 2019年第13期25卷 1560-1565页

作者： mohammed mohammed El-Said Sameh Hany Emile Colorectal Surgery Unit General Surgery Department Mansoura University Hospitals Mansoura University

Cellular therapy may be the solution of challenging problems in colorectal surgery such as impaired healing leading to anastomotic leakage and metastatic colorectal cancer(CRC). This review aimed to illustrate the role of cellular therapy in promotion of wound healing and management of metastatic CRC. An organized literature search for the role of cellular therapy in promotion of wound healing and management of metastatic CRC was conducted. Electronic databases including PubMed/Medline, Scopus, and Embase were queried for the search process. Two types of cellular therapy have been recognized, the mesenchymal stem cells(MSCs) and bone marrow-mononuclear cells(BM-MNCs) *** cells have been shown to accelerate and promote healing of various tissue injuries in animal and human studies. In addition, experimental studies have reported that MSCs may help suppress the progression of colon cancer in rat models. This article reviews the possible mechanisms of action and clinical utility of MSCs and BM-MNCs in promotion of healing and suppression of tumor growth in light of the published literature. Cellular therapy has a potentially important role in colorectal surgery, particularly in the promotion of wound healing and management of metastatic CRC. Future directions of cellular therapy in colorectal surgery were explored which may help stimulate futures studies on the role of cellular therapy in colorectal surgery.

关键词： Cellular therapy Future Colorectal surgery Stem cells