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An Efficient Medium Access Control Mechanism for Flying Ad-hoc Networks

Computer Systems Science & Engineering 2021年第7期38卷 47-63页

作者： Muhammad Asghar Khan Fazal Noor Insaf Ullah Sajjad ur Rehman Shibli Nisar mohaira ahmad Department of Electronic Engineering ISRA UniversityIslamabad44000Pakistan Department of Computer Science and Information Systems Islamic University of MadinahMadinah400411Saudi Arabia Hamdard Institute of Engineering&Technology Islamabad44000Pakistan Department of Electrical Engineering Namal InstituteMianwali42200Pakistan Department of Electrical Engineering National University of Sciences and Technology(NUST)Islamabad44000Pakistan

The Flying Ad-hoc Networks(FANETs)is characterized by the transition from a single large Unmanned Aerial Vehicle(UAV)to multiple small UAVs connected in an ad-hoc *** high mobility is the core feature of such networks,they are prone to route breaks within the *** issue of connectivity loss can be coped with,to some extent,by making use of omnidirectional *** modification,however,curtails Quality-of-Service(QoS)requirements of networks in terms of bandwidth,media access delay,coverage and ***,directional antennas have advantages over omnidirectional antennas such as improved transmission range,spatial reuse and high ***,its introduction raises location-dependent issues to the Medium Access Control(MAC)*** calls for an efficient MAC protocol that can cater to new directional antenna models and,at the same time,can counter the constraints associated with the dynamic ***,in this article,we consider a UAV interconnection mechanism that lets the UAVs execute the communication tasks using the directional MAC *** technique is advantageous as compared to the approach of utilizing the MAC protocol using omnidirectional *** scheme is being implemented as a case study for Industry 4.0 inventory and traceability applications in the *** modeling and simulation purposes,we use the Optimized Network Engineering Tool(OPNET)and aim to seek an evaluation with respect to throughput,media access delay,retransmission attempts and data *** results obtained demonstrate the effectiveness of the proposed scheme.

关键词： FANETs QoS Industry 4.0 IEEE 802.11 MAC OPNET mobility models directional antenna

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Finite element model updating for structural damage detection using transmissibility data

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Earthquake Engineering and Engineering Vibration 2024年第1期23卷 87-101页

作者： ahmad Izadi Akbar Esfandiari Department of Maritime Engineering Amirkabir University of TechnologyTehran 15875-4413Iran

This paper presents a new finite element model updating method for estimating structural parameters and detecting structural damage location and severity based on the structural responses(output-only data).The method uses the sensitivity relation of transmissibility data through a least-squares algorithm and appropriate normalization of the extracted *** proposed transmissibility-based sensitivity equation produces a more significant number of equations than the sensitivity equations based on the frequency response function(FRF),which can estimate the structural parameters with higher *** abilities of the proposed method are assessed by using numerical data of a two-story two-bay frame model and a plate structure *** evaluating different damage cases,the number,location,and stiffness reduction of the damaged elements and the severity of the simulated damage have been accurately *** reliability and stability of the presented method against measurement and modeling errors are examined using error-contaminated *** parameter estimation results prove the method’s capabilities as an accurate model updating algorithm.

关键词： damage detection model updating output-only transmissibility sensitivity equation

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Correlation between structural phase transition and physical properties of Co^(2+)/Gd^(3+)co-substituted copper ferrite

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Journal of Rare Earths 2024年第7期42卷 1344-1353,I0006页

作者： Mohsen Choupani ahmad Gholizadeh School of Physics Damghan UniversityDamghan36716-45667Iran

The doping of the spinel ferrites with selective cations usually improves the properties of the parent *** effect of Co^(2+)/Gd^(3+)co-substitution on the microstructure,optical,and magnetic properties of Cu1-xCoxFe2-xGdxO4 prepared by the citrate-nitrate auto-combustion synthesis was *** of the samples was performed with powder X-ray diffraction(XRD),Raman and Fouriertransform infrared(FTIR)spectroscopy,field-emission scanning electron microscopy,X-ray energydispersive spectroscopy,UV-Vis spectroscopy,and a vibrating sample *** results of XRD,Raman,and FTIR analysis show a gradual structural phase transition from a tetragonal(I41/amd)structure to a cubic(Fd3m)*** bandgap energy of the studied samples is in a range of 1.57-1.75 eV with a minimum in sample x=0.06 and then *** investigations show that the presence of Co^(2+)/Gd^(3+)cations in an octahedral site of the copper ferrite structure could increase saturation magnetization and coercive field from 567.9 Oe and 23.62 emu/g to 929.4 Oe and 28.27 emu/g,respectively.

关键词： Spinel copper ferrite Citrate-nitrate method Structure phase transition Microstructure properties Magnetic properties Rare earths

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Rotating effects on the thermophysical properties of a two-dimensional GaAs quantum ring

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Communications in Theoretical Physics 2024年第6期76卷 165-173页

作者： ahmad Ghanbari Department of Physics College of ScienceYasouj UniversityYasoujIran

In this work,we have investigated the rotating effect on the thermodynamic properties of a 2D quantum ***,we have considered the radial potential of a 2D quantum ring and solved the Schrödinger equation in the presence of the Aharonov-Bohm effect and a uniform magnetic field for the considered *** to the solution of the equation,we calculated the eigenvalues and eigenfunctions of the considered *** the calculated energy spectrum,we obtained the partition function and thermodynamic properties of the system,such as the mean energy,specific heat,entropy and free *** results show that the rotating effect has a significant influence on the thermophysical properties of a 2D quantum *** also study other effects of the rotating term:(1)the effect of different values of rotating parameters,and(2)the effect of negative rotation on the thermodynamic properties of the *** results are discussed in detail.

关键词： Schrodinger equation quantum ring rotation effect thermophysical properties

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Unlocking the Potential:A Comprehensive Systematic Review of ChatGPT in Natural Language Processing Tasks

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Computer Modeling in Engineering & Sciences 2024年第10期141卷 43-85页

作者： Ebtesam ahmad Alomari Faculty of Computing and Information Albaha UniversityAlbaha65731Saudi Arabia

As Natural Language Processing(NLP)continues to advance,driven by the emergence of sophisticated large language models such as ChatGPT,there has been a notable growth in research *** rapid uptake reflects increasing interest in the field and induces critical inquiries into ChatGPT’s applicability in the NLP *** review paper systematically investigates the role of ChatGPT in diverse NLP tasks,including information extraction,Name Entity Recognition(NER),event extraction,relation extraction,Part of Speech(PoS)tagging,text classification,sentiment analysis,emotion recognition and text *** novelty of this work lies in its comprehensive analysis of the existing literature,addressing a critical gap in understanding ChatGPT’s adaptability,limitations,and optimal *** this paper,we employed a systematic stepwise approach following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)framework to direct our search process and seek relevant *** review reveals ChatGPT’s significant potential in enhancing various NLP *** adaptability in information extraction tasks,sentiment analysis,and text classification showcases its ability to comprehend diverse contexts and extract meaningful ***,ChatGPT’s flexibility in annotation tasks reducesmanual efforts and accelerates the annotation process,making it a valuable asset in NLP development and ***,GPT-4 and prompt engineering emerge as a complementary mechanism,empowering users to guide the model and enhance overall *** its promising potential,challenges *** performance of ChatGP Tneeds tobe testedusingmore extensivedatasets anddiversedata ***,its limitations in handling domain-specific language and the need for fine-tuning in specific applications highlight the importance of further investigations to address these issues.

关键词： Generative AI large languagemodel(LLM) natural language processing(NLP) ChatGPT GPT(generative pretraining transformer) GPT-4 sentiment analysis NER information extraction annotation text classification

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Evaluation of soil loss severity and ecological restoration approach for sustainable agriculture in the Hindu Kush, Karakoram and Himalaya region

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Journal of Mountain Science 2024年第5期21卷 1509-1521页

作者： Arshad ASHRAF Imran ahmad Climate Energy and Water Research InstituteNational Agricultural Research Centre(NARC)Islamabad 44000Pakistan

Soil erosion has resulted in removal of the topsoils containing fine soil particles and plant nutrients, causing decrease in soil fertility in the Hindu Kush, Karakoram and Himalaya(HKH) region. The existing production of cereal crop grains has been reduced to one third of the potential crop grains production owing to land degradation and poor farming practices. It is necessary to assess risk of soil loss and identify appropriate controlling measures to address issues of low agriculture productivity and water insecurity in the region. In the present study, severity of soil loss was predicted using Revised Universal Loss Equation(RUSLE) and ecological measures were identified for sustainable mountain agriculture in the HKH region of Upper Indus Basin, Pakistan. Overall 62.6% area was found to have very low risk of soil loss, i.e., 100 t/(ha·yr) in about 6.8% and 7.4% areas respectively. The mean rate of soil loss was about 41.9 t/(ha·yr) in the Hindu Kush, 31.1 t/(ha·yr) in the Himalayas, 18.8 t/(ha·yr) in the Karakoram and overall 29.7 t/(ha·yr) in the three HKH ranges. As such no considerable measures have been adopted by the communities for restoration of the degraded areas except raising fruit/farm trees and supporting limited social forestry for their livelihoods. The slopes cleared for cultivation and susceptible to erosion may be stabilized through sowing/planting of multi-purpose plant species and formation of proper bench terraces. The conservation of forest ecosystem and pastures at higher elevations would help in reducing overland water flow, risk of flash flood hazard and minimizing sediment loads in the downstream. It is essential to adopt site-specific resource conservation techniques and restore possible ecosystem health for sustainable agriculture and economic developm

关键词： Climate change Erodibility Indus basin Land degradation Slope stabilization

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Federated Learning Security and Privacy-Preserving Algorithm and Experiments Research Under Internet of Things Critical Infrastructure

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Tsinghua Science and Technology 2024年第2期29卷 400-414页

作者： Nasir ahmad Jalali Hongsong Chen Department of Computer Science University of Science and Technology Beijing(USTB)Beijing 100083China

The widespread use of the Internet of Things(IoTs)and the rapid development of artificial intelligence technologies have enabled applications to cross commercial and industrial band *** such systems,all participants related to commercial and industrial systems must communicate and generate ***,due to the small storage capacities of IoT devices,they are required to store and transfer the generated data to third-party entity called“cloud”,which creates one single point to store their ***,as the number of participants increases,the size of generated data also ***,such a centralized mechanism for data collection and exchange between participants is likely to face numerous challenges in terms of security,privacy,and *** address these challenges,Federated Learning(FL)has been proposed as a reasonable decentralizing approach,in which clients no longer need to transfer and store real data in the central ***,they only share updated training models that are trained over their private *** the same time,FL enables clients in distributed systems to share their machine learning models collaboratively without their training data,thus reducing data privacy and security ***,slow model training and the execution of additional unnecessary communication rounds may hinder FL applications from operating properly in a distributed ***,these unnecessary communication rounds make the system vulnerable to security and privacy issues,because irrelevant model updates are sent between clients and ***,in this work,we propose an algorithm for fully homomorphic encryption called Cheon-Kim-Kim-Song(CKKS)to encrypt model parameters for their local information privacy-preserving *** proposed solution uses the impetus term to speed up model convergence during the model training ***,it establishes a secure communication channel between IoT devices and the *** a

关键词： Federated Learning(FL) Internet of Things(IoTs) lightweight Transport Layer Security(iTLS) Cheon-Kim-Kim-Song(CKKS)

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Optimizing calcination of coal by-products for maximizing REE leaching recovery and minimizing Al,Ca,and Fe contamination

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Journal of Rare Earths 2024年第7期42卷 1354-1365,I0006页

作者： Tushar Gupta ahmad Nawab Rick Honaker MP Materials Mountain Pass Mine 67750 Bailey RoadMountain PassCA92366USA Department of Mining Engineering University of KentuckyLexingtonKY40506USA

High-temperature calcination is effective in improving the leaching characteristics of rare earth elements(REEs)from conventional REE-bearing minerals by transforming them into more leachable ***,the recovery of contaminants such as Al,Fe,and Ca also increases *** objective of the study was to maximize the REE extraction while minimizing the concentration of contaminant ions(Al,Ca,and Fe)in the leach *** density fractions of the coarse refuse from the Baker and Fire Clay seam coal refuse were pulverized to a top size of 180μm and used as a feedstock for the *** the samples generated from thermal treatment were leached at 1%(w/v)using 1.2 mol/L sulfuric acid at 75℃ for 2 *** results from a parametric program based on a Box-Behnken design were used for modeling and optimization of three operating parameters associated with the lab-scale calcination *** parameters included temperature(400-800℃),ramp rate(2-10℃/min)and holding time(0-120 min).It was determined that the calcination temperature was the most significant parameter influencing REE *** majority of the heavy rare earth elements(HREEs)were found to be present in an insoluble form in the calcination products and were marginally affected by thermal treatment.A strong correlation between light rare earth elements recovery(LREEs)and Al suggested a possible association with *** optimum operating conditions for high REE recovery with comparatively lower contaminant concentration for 1.6 specific gravity float and 2.2 sink fractions of Baker and Fire Clay seam material were determined to be at 776,800℃ and 407,800℃,calcining temperatures,respectively.A higher optimum temperature of 1.6 float fraction of Baker seam relative to Fire Clay seam material was due to elevated pyrite concentration in Baker seam *** treatment at 400℃ converted pyrite into a soluble intermedium iron oxide,resulting in a high Fe content in the ***

关键词： Calcination Optimization Rare earth elements Coal refuse

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Applying the Protective Mn-Co-La_(2)O_(3)Coating on Crofer 22 APU Ferritic Stainless Steel Used as Solid Oxide Fuel Cell Interconnects

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Acta Metallurgica Sinica(English Letters) 2024年第5期37卷 872-888页

作者： Farhad Mohsenifar Hadi Ebrahimifar ahmad Irannejad Department of Materials Engineering and Metallurgy Faculty of EngineeringShahid Bahonar University of KermanKermanIran Mechanical Engineering Department Faculty of EngineeringHigher Education Complex of Bam76615-314BamIran Department of Materials Engineering Faculty of Mechanical and Materials EngineeringGraduate University of Advanced TechnologyKerman ***Iran

This research studies the effect of Mn-Co-La_(2)O_(3) coating synthesized by the electrodeposition method on the oxidation resistance and electrical conductivity of the Crofer 22 APU stainless steel interconnect plates in solid oxide fuel *** test samples were characterized by a field emission scanning electron microscope(FESEM)equipped with energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).The oxidation kinetics of the coated and uncoated samples were studied by tracking their weight changes over time at 800°C,showing that the oxidation mechanism for all samples follows the parabolic *** oxidation rate constant(k_(p))values of the coated sample compared with that of the uncoated one indicated a reduction in the oxidation rate of the steel substrate in the presence of the Mn-Co-La_(2)O_(3) *** examination of the cross-section of different samples after the isothermal oxidation for 500 h at 800°C exhibited that applying the composite coating leads to a decrease in the thickness of the chromia layer formed on the steel ***,under these conditions,the area-specific resistance(ASR)of the coated sample(13.11 mΩcm^(2))is significantly lower than that of the uncoated one(41.45 mΩcm^(2)).

关键词： Area specific resistance Oxidation Fuel cell Composite coating

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Influence of Brownian Motion, Thermophoresis and Magnetic Effects on a Fluid Containing Nanoparticles Flowing over a Stretchable Cylinder

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Fluid Dynamics & Materials Processing 2024年第3期20卷 525-536页

作者： Aaqib Majeed ahmad Zeeshan Department of Mathematics The University of FaisalabadFaisalabad38000Pakistan Department of Mathematics and Statistics FBASInternational Islamic University IslamabadIslamabad44000Pakistan

The influence of Brownian motion and thermophoresis on a fluid containing nanoparticles flowing over a stretchable cylinder is *** classical Navier-Stokes equations are considered in a porous *** addition,the Lorentz force is taken into *** controlling coupled nonlinear partial differential equations are transformed into a system of first order ordinary differential equations by means of a similarity *** resulting system of equations is solved by employing a shooting approach properly implemented in *** evolution of the boundary layer and the growing velocity is shown graphically together with the related profiles of concentration and *** magnetic field has a different influence(in terms of trends)on velocity and concentration.

关键词： Mixed convection Brownian motion heat transfer porous surface velocity slip

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