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New insights on thermal ageing of electrical insulating oils as revealed from photoluminescence and absorption spectroscopy

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High Voltage 2024年第5期9卷 1033-1045页

作者： hesham s.karaman Eman G.Atiya Diaa-Eldin A.Mansour Mohsen Ghali Z.M.s.Elbarbary Manal M.Emara Department of Electrical Engineering Faculty of Engineering at ShoubraBenha UniversityCairoEgypt Department of Electrical Power and Machines Engineering Faculty of EngineeringTanta UniversityTantaEgypt Department of Electrical Power Engineering Faculty of EngineeringEgypt-Japan University of Science and Technology(E-JUST)New Borg El-Arab CityAlexandriaEgypt Department of Energy Materials Institute of Basic and Applied ScienceEgypt-Japan University of Science and Technology(E-JUST)New Borg El-Arab CityAlexandriaEgypt Department of Physics Faculty of ScienceKafrelsheikh UniversityKafrelsheikhEgypt Department of Electrical Engineering College of EngineeringKing Khalid UniversityAbhaSaudi Arabia Center for Engineering and Technology Innovations King Khalid UniversityAbhaSaudi Arabia Department of Electrical Engineering Faculty of EngineeringKafrelsheikh UniversityKafrelsheikhEgypt

Recently,significant efforts have been exerted to replace mineral oil with environmentally friendly oils due to safety and environmental ***,there is a need to clarify the physical mechanisms behind the ageing impact of these *** authors use advanced optical spectroscopy techniques in correlation with dielectric measurements to understand the ageing processes in environmentally friendly oils as well as mineral ***,different samples of environmentally friendly oils and mineral oil were utilised to investigate the ageing *** samples were subjected to different ageing periods using a thermal accelerated ageing ***,the severity of the produced byproducts due to the oil degradation is examined based on several measured properties representing macroscopic and microscopic *** macroscopic category was evaluated through dielectric properties,including breakdown voltage,dielectric permittivity,and dissipation *** microscopic category,on the other hand,was assessed using techniques such as ultraviolet-visible absorption spectroscopy and photoluminescence *** techniques enabled a deep understanding of the molecular-level changes occurring in the oil under ageing conditions,thereby getting new insights into oil ageing *** is worth mentioning that natural ester oil demonstrated the most favourable performance across various properties under ageing conditions.

关键词： absorption thermal spectroscopy

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Visa trial of international trade:evidence from support vector machines and neural networks

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Journal of Management Analytics 2020年第2期7卷 231-252页

作者： Engin Akman Abdullah s.karaman Cemil Kuzey Ankara Turkey College of Engineering and Technology American University of the Middle EastKuwait Arthur J.Bauernfeind College of Business Murray State UniversityMurrayKYUSA

International trade depends on networking,interaction and in-person meetings which stimulate cross-border *** countries are seeking policies to encourage inbound mobility to support bilateral trade,tourism,and foreign direct *** nations have been implementing liberal visa regimes as an important part of facilitating policies in view of security *** has been among the nations introducing liberal visa policies to support trade in the last decade and recorded significant increases in the volumes of *** this paper,we employed machine learning methodologies,support vector machines(sVM)and Neural networks(NN),to investigate the facilitating impact of liberal visa policies on bilateral trade,using the export data from Turkey for the period of 2000–*** research disentangled the variables that have the strongest impact on trade utilizing sVM and NN models and exhibited that visa policies have significant impacts on the bilateral *** relaxed visa policies are recommended for the countries in the pursuit of increasing exports.

关键词： trade modeling visa policy support vector machine neural network

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Balancing the Power Consumption speed in Flat and Hierarchical WsN

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International Journal of Automation and computing 2008年第4期5卷 366-375页

作者： hesham Abusaimeh Department of Computer science Loughborough University

A combination of a cluster tree routing protocol and an Ad hoc on demand vector (AODV) routing protocol is used in the latest ZigBee standard wireless sensor networks (WsNs) ***,the AODV routing protocol has no means by which to take into consideration the power consumption of the nodes during the routing ***,a new approach is proposed in this paper to balance the power consumption speed and to distribute the responsibilities of routing among flat wireless sensor nodes and the three levels of hierarchical wireless sensor *** three levels are based on the three types of devices,which are used in the ZigBee standard:the coordinator,the routers,and the end *** this paper,we have compared the original AODV routing protocol with our extension approach for the distribution of power *** on the simulation results,our new approach has achieved better performance in terms of increasing the lifetime of the flat wireless sensor network,the personal area network (PAN) coordinator,the routers,and the whole network of the hierarchical wireless sensor ***,it has better performance in terms of distributing the power consumption among the key nodes of the wireless sensor network.

关键词： Routing protocols energy consumption Ad hoc on-demand distance vector (AODV) network lifetime wireless sensor networks (WsNs).

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Dynamic Cluster Head for Lifetime Efficiency in WsN

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International Journal of Automation and computing 2009年第1期6卷 48-54页

作者： hesham Abusaimeh Department of Computer science Loughborough University Loughborough

saving energy and increasing network lifetime are significant challenges in wireless sensor networks （WsNs）. In this paper, we propose a mechanism to distribute the responsibility of cluster-heads among the wireless sensor nodes in the same cluster based on the ZigBee standard, which is the latest WsN standard. ZigBee supports ad hoc on-demand vector （AODV） and cluster-tree routing protocols in its routing layer. However, none of these protocols considers the energy level of the nodes in the network establishing process or in the data routing process. The cluster-tree routing protocol supports single or multi-cluster networks. However, each single cluster in the multi-cluster network has only one node acting as a cluster head. These cluster-heads are fixed in each cluster during the network lifetime. Consequently, using these cluster-heads will cause them to die quickly, and the entire linked nodes to these cluster-heads will be disconnected from the main network. Therefore, the proposed technique to distribute the role of the cluster head among the wireless sensor nodes in the same cluster is vital to increase the lifetime of the network. Our proposed technique is better in terms of performance than the original structure of these protocols. It has increased the lifetime of the wireless sensor nodes, and increased the lifetime of the WsN by around 50% of the original network lifetime.

关键词： Cluster-tree routing protocol cluster head energy consumption ad hoc on-demand distance vector (AODV) networklifetime wireless sensor networks (WsNs).

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3D finite element analysis of composite noise barrier con- structed of polyurethane products

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Frontiers of structural and Civil Engineering 2017年第1期11卷 100-110页

作者： Ben DAEE hesham El NAGGAR Department of Civil and Environmental Engineering the University of Western Ontario London ON N6A 5B9 Canada

This paper presents a numerical investigation on the structural performance of an innovative noise barrier consisting of poly-block, rigid polyurethane foam （RPF） and polyurea. The mechanical characteristics of RPF as well as the flexural resistance of the proposed wall system （poly-wall） were established and presented in another study. The experimental results are used in the current study to develop, calibrate and verify 3D finite element （FE） models of the wall system. The components of the poly-wall including steel rebars, poly-blocks and RPF cores were simulated and then verified using the results of experiments conducted on the wall components. The results of numerical analysis exhibited a satisfactory agreement with the experimental outcomes for the entire wall system. The verified numerical models were then used to conduct a parametric study on the performance of poly-wall models under uniform wind load and gravity load. The findings of the current study confirmed that the structural performance of poly-wall is satisfactory for noise barrier application. simulation techniques for improvement of the numerical analysis of multi-martial 3D FE models were discussed.

关键词： 3D finite element sound wall rigid polyurethane foam poly-wall numerical model calibration

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Accelerated mineralization on nanofibers via non-thermal atmospheric plasma assisted glutamic acid templated peptide conjugation

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Regenerative Biomaterials 2019年第4期6卷 231-240页

作者： Günnur Onak Ozan karaman Tissue Engineering and Regenerative Medicine Laboratory Department of Biomedical Engineering_Izmir Katip C¸elebi University_Izmir 35620Turkey Bonegraft Biomaterials Co. Ege University TechnopolisBornova_Izmir 35100Turkey

surface modification by non-thermal atmospheric plasma(NTAP)treatment can produce significantly higher carboxylic groups on the nanofibers(NF)surface,which potentially can increase biomineralization of NF via promoting glutamic acid(GLU)templated peptide ***,electrospun poly(lactide-co-glycolide)(PLGA)scaffolds were treated with NTAP and conjugated with GLU peptide followed by incubation in simulated body fluids for *** effect of NTAP treatment and GLU peptide conjugation on mineralization,surface wettability and roughness were *** results showed that NTAP treatment significantly increased GLU peptide conjugation which consequently enhanced mineralization and mechanical properties of NTAP treated and peptide conjugated NF(GLU-pNF)compared to neat PLGA NF,NTAP treated NF(pNF)and GLU peptide conjugated NF(GLU-NF).The effect of surface modification on human bone marrow derived mesenchymal stem cells adhesion,proliferation and morphology was evaluated by cell proliferation assay and fluorescent *** demonstrated that cellular adhesion and proliferation were significantly higher on GLU-pNF compared to NF,pNF and *** summary,NTAP treatment could be a promising modification technique to induce biomimetic peptide conjugation and biomineralization for bone tissue engineering applications.

关键词： nanofibers biomineralization non-thermal atmospheric plasma bone tissue engineering

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NeTrainsim:a network-level simulator for modeling freight train longitudinal motion and energy consumption

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Railway Engineering science 2024年第4期32卷 480-498页

作者： Ahmed s.Aredah Karim Fadhloun hesham A.Rakha Center for sustainable Mobility Virginia Tech Transportation Institute3500 Transportation Research PlazaBlacksburgVA 24061USA

Although train modeling research is vast, most available simulation tools are confined to city-or trip-scale analysis, primarily offering micro-level simulations of network segments. This paper addresses this void by developing the Ne Train sim simulator for heavy long-haul freight trains on a network of multiple intersecting tracks. The main objective of this simulator is to enable a comprehensive analysis of energy consumption and the associated carbon footprint for the entire train system. Four case studies were conducted to demonstrate the simulator's performance. The first case study validates the model by comparing Ne Train sim output to empirical trajectory data. The results demonstrate that the simulated trajectory is precise enough to estimate the train energy consumption and carbon dioxide emissions. The second application demonstrates the train-following model considering six trains following each other. The results showcase the model ability to maintain safefollowing distances between successive trains. The next study highlights the simulator's ability to resolve train conflicts for different scenarios. Finally, the suitability of the Ne Train sim for modeling realistic railroad networks is verified through the modeling of the entire Us network and comparing alternative powertrains on the fleet energy consumption.

关键词： Ne Train sim Network train simulation Train longitudinal motion Energy consumption Carbon footprint

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Fabrication of PMMA nanocomposite biomaterials reinforced by cellulose nanocrystals extracted from rice husk for dental applications

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Friction 2024年第12期12卷 2808-2825页

作者： Ahmed FOULY Walid M.DAOUsH hesham I.ELQADY Hany s.ABDO Mechanical Engineering Department College of EngineeringKing Saud UniversityRiyadh 11421Saudi Arabia The King salman Center for Disability Research Riyadh 11421Saudi Arabia Department of Production Engineering and Mechanical Design Faculty of EngineeringMinia UniversityMinia 61519Egypt Department of Chemistry College of ScienceImam Mohammad Ibn Saud Islamic University(IMSIU)Riyadh 11623Saudi Arabia Faculty of Technology and Education Helwan UniversityCairo 11281Egypt Faculty of Engineering Aswan UniversityAswan 81528Egypt Center of Excellence for Research in Engineering Materials(CEREM) King Saud UniversityRiyadh 11421Saudi Arabia Mechanical Design and Materials Department Faculty of Energy EngineeringAswan UniversityAswan 81521Egypt

The primary objective of global studies is to develop the properties and durability of polymers for various *** it comes to dental disability,denture base materials must have sufficient mechanical and tribological performance in order to withstand the forces experienced in the *** work aims to investigate the effects of the addition of low content of cellulose nanocrystals(CNC)on the mechanical and tribological performance of the polymethyl methacrylate(PMMA)*** weight percent of CNC(0,0.2,0.4,0.6,and 0.8 wt%)were added to the PMMA matrix followed by ball milling to evenly distribute the nanoparticles reinforced phase in the matrix *** findings emphasize the significant impact of CNC integration on the performance of PMMA *** increasing the content of the CNC nanoparticles,the mechanical properties of PMMA were *** addition,the tribological outcomes demonstrated a significant reduction in the friction coefficient besides an enhancement in the wear resistance as the weight percentage of nanoparticles *** surface of the worn samples was investigated by utilizing sEM to identify the wear mechanisms corresponding to the different *** addition,a finite elment model(FEM)was developed to ascertain the thickness of the worn layer and the generated stressed on the surfaces of the nanocomposite throughout the friction process.

关键词： polymethyl methacrylate nanocomposite cellulose nanocrystals denture materials rice husk polymethyl methacrylate(PMMA) wear resistance

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Geotechnical investigations and remediation design for failure of tunnel portal section： a case study in northern Turkey

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Journal of Mountain science 2017年第6期14卷 1140-1160页

作者： Ayberk KAYA Kadir karaman Fikri BULUT Recep Tayyip Erdogan University Faculty of Engineering Department of Geological Engineering 53100 Rize Turkey Karadeniz Technical University Faculty of Engineering Department of Mining Engineering 61080 Trabzon Turkey Karadeniz Technical University Faculty of Engineering Department of Geological Engineering 61080 Trabzon Turkey

Mass movements are very common problems in the eastern Black sea region of Turkey due to its climate conditions, geological, and geomorphological characteristics. High slope angle, weathering, dense rainfalls, and anthropogenic impacts are generally reported as the most important triggering factors in the region. Following the portal slope excavations in the entrance section of Cankurtaran tunnel, located in the region, where the highly weathered andesitic tuff crops out, a circular toe failure occurred. The main target of the present study is to investigate the causes and occurrence mechanism of this failure and to determine the feasible remedial measures against it using finite element method(FEM) in four stages. These stages are slope stability analyses for pre-and postexcavation cases, and remediation design assessments for slope and tunnel. The results of the FEM-ssR analyses indicated that the insufficient initial support design and weathering of the andesitic tuffs are the main factors that caused the portal failure. After installing a rock retaining wall with jet grout columns and reinforced slope benching applications, the factor of safety increased from 0.83 to 2.80. In addition toslope stability evaluation, the Rock Mass Rating(RMR), Rock Mass Quality(Q) and New Austrian Tunneling Method(NATM) systems were also utilized as empirical methods to characterize the tunnel ground and to determine the tunnel support design. The performance of the suggested empirical support design, induced stress distributions and deformations were analyzed by means of numerical modelling. Finally, it was concluded that the recommended stabilization technique was essential for the dynamic long-term stability and prevents the effects of failure. Additionally, the FEM method gives useful and reasonably reliable results in evaluating the stability of cut slopes and tunnels excavated both in continuous and discontinuous rock masses.

关键词： Portal failure stability analysis Finite element method Tunnel support design Remedial measures Rock Mass Rating(RMR) Rock Mass Quality(Q) New Austrian Tunneling Method(NATM)

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Comparison of bacterial community structures in two systems of a sewage treatment plant using PCR-DGGE analysis

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Journal of Environmental sciences 2011年第12期23卷 2049-2054页

作者： Abd El-Latif hesham Rong Qi Min Yang state Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China Genetics Department Faculty of Agriculture Assiut University Assiut Egypt

The combination of PCR amplification of 16s rRNA genes with denaturing gradient gel electrophoresis （DGGE） analysis was used to reveal the compositions and dynamics of bacterial communities in a sewage treatment plant with two systems, i.e., an anoxic- anaerobic-aerobic system （inverted A2O） and an anaerobic-anoxic-aerobic one （conventional A2O） over a period from February to July 2009, during which both systems experienced serious sludge bulking problems. The DGGE patterns showed that there were many common bands in both systems, suggesting the high similarity of bacterial communities of the two systems. Meanwhile, the moving window correlation analysis showed that the two systems experienced different microbial community structure changes during the period, which might be related with the different situations of the occurrence and disappearance of sludge bulking, as being reflected by sludge volume index （sVI） values. Major bands of DGGE patterns of sludge samples were further sequenced. Phylogenetic affiliation indicated that the majority of the sequences obtained were affiliated with Actinobacteria, Firmicutes, Bacteroidetes/Chlorobi group and α- and β-Proteobacteria. Two sequences showed high similarities to typical filamentous bacteria Microthrix parvicella and Nostocoida limicola I, indicating that these bacterial species have been involved in the sludge bulking problems.

关键词： PCR-DGGE bacterial community activated sludge sludge bulking sewage treatment plant

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