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A Review of Wideband Circularly Polarized Dielectric Resonator Antennas

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China Communications 2017年第6期14卷 65-79页

作者： Ubaid Ullah Mohd Fadzil Ain zainal arifin ahmad School of Electrical and Electronic Engineering Universiti Sains Malaysia Nibong Tebal 14300 Pulau Pinang Malaysia School of Material and Mineral Resource Engineering Universiti Sains Malaysia Nibong Tebal 14300 Pulau Pinang Malaysia

This article presents a technical review of circularly polarized(CP) dielectric resonator antennas(DRA) for wideband *** primary objective of this review is,to highlight the techniques used by different researchers for generating circular polarization in ***,a general idea of circular polarization and it advantages over linear polarization is presented,and then all the major developments made in the CP DRA are *** emphasis of the paper is on the wideband circularly polarized dielectric resonator *** current state of the art and all the realizable features of the CP DRA are addressed ***,some recommendations for future CP DRAs are given and the paper ends with concluding remarks.

关键词： circularly polarized dielectric resonator antenna dielectric resonator antenna circular polarization techniques

A Short Review on Copper Calcium Titanate(CCTO) Electroceramic;Synthesis,Dielectric Properties,Film Deposition,and Sensing Application

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Nano-Micro Letters 2016年第4期8卷 291-311页

作者： Mohsen ahmadipour Mohd Fadzil Ain zainal arifin ahmad Structural Materials Niche Area School of Materials and Mineral Resources EngineeringUniversiti Sains MalaysiaEngineering Campus School of Electrical and Electronic Engineering Universiti Sains Malaysia Engineering Campus

Electroceramic calcium copper titanates(CaCu3Ti4O12,CCTO),with high dielectric permittivities（e） of approximately 105 and 104,respectively,for single crystal and bulk materials,are produced for a number of wellestablished and emerging applications such as resonator,capacitor,and *** applications take advantage of the unique properties achieved through the structure and properties of *** review comprehensively focuses on the primary processing routes,effect of impurity,dielectric permittivity,and deposition technique used for the processing of electroceramics along with their chemical composition and micro and *** is given to versatile and basic approaches that allow one to control the microstructural features that ultimately determine the properties of the CCTO *** the intensive research in this area,none of the studies available in the literature provides all the possible relevant information about CCTO fabrication,structure,the factors influencing its dielectric properties,CCTO immobilization,and sensing applications.

关键词： CCTO Chemical synthesis Dielectric permittivity Loss factor Deposition Sensitivity

Effects of La_(2)O_(3) addition on microstructure development and physical properties of harder ZTA-CeO_(2) composites with sustainable high fracture toughness

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Journal of Rare Earths 2021年第7期39卷 844-849,I0003页

作者： Zhwan Dilshad Ibrahim Sktani Nik Akmar Rejab Abdul Fatah Zulkarnain Rosli Ali Arab zainal arifin ahmad Department of Mechanical and Energy Engineering Erbil Technical Engineering CollegeErbil Polytechnic UniversityErbil44001Iraq Structural Materials Niche Area School of Materials and Mineral Resources EngineeringEngineering CampusUniversiti Sains Malaysia14300Nibong TebalPenangMalaysia State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

The influence of La_(2)O_(3) inclusion(0-3 wt%) on the micro structure,phase formation and mechanical properties of zirconia toughed alumina(ZTA) added with 5.0 wt% CeO_(2) was *** CeO_(2) composites were sintered at 1600℃ for 4 *** microstructure,phase formation,density,fracture toughness and hardness properties were characterised through FESEM,Microscopy Image Analysis Software and XRD diffractometer,Archimedes principle and Vickers indentation technique,*** XRD,image processing and FESEM reveal the existence of LaAl_(11)O_(18).The addition of La_(2)O_(3) incites the sintering,microstructure refinement,densification of ZTA-CeO_(2) matrix and phase ***,the hardness of ZTA-CeO_(2) ceramics is increased rapidly based on refinement of Al_(2)O_(3) grains,densification of ZTA-CeO_(2) composites and porosity *** is observed that the fracture toughness is enhanced through in situ formation of elongated LaAl_(11)O_(18) *** addition of 0.7 wt% La_(2)O_(3) culminated in the achievement of the optimum findings for density(4.41 g/cm^(3)),porosity(0.46%),hardness(1792 HV) and fracture toughness(8.8 MPa·m^(1/2)).Nevertheless,excess La_(2)O_(3) is proven to be detrimental as it displays poor mechanical properties due to the poor compactness of numerous LaAl_(11)O_(18) grains,coarsening of Al_(2)O_(3) grains and decline in density.

关键词： ZTA-CeO_(2) Ceramic composite Microstructural design Fracture toughness Vickers hardness Rare earths

Selectivity of CO_(2)reduction reaction to CO on the graphitic edge active sites of Fe-single-atom and dual-atom catalysts:A combined DFT and microkinetic modeling

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Carbon Resources Conversion 2024年第1期7卷 21-31页

作者： ahmad Nuruddin Adhitya Gandaryus Saputro arifin Luthfi Maulana Febdian Rusydi Fiki Taufik Akbar Hadi Teguh Yudistira Hermawan Kresno Dipojono Advanced Functional Materials Research Group Faculty of Industrial TechnologyInstitut Teknologi BandungJl.Ganesha No.10Bandung 40132Indonesia Research Center for Nanosciences and Nanotechnology Institut Teknologi BandungJl.Ganesha No.10Bandung 40132Indonesia Research Center for Quantum Engineering Design Department of PhysicsFaculty of Science and TechnologyUniversitas AirlanggaSurabaya 60115Indonesia Theoretical High Energy Physics Research Division Faculty of Mathematics and Natural SciencesInstitut Teknologi BandungJl.Ganesha No.10Bandung 40132Indonesia Mechanical Engineering Study Program Institut Teknologi Sumatera(ITERA)South LampungLampungIndonesia Department of Materials Science and Engineering University of CaliforniaBerkeleyBerkeleyCA 94720United States

We study the carbon dioxide reduction reaction(CO_(2)RR)activity and selectivity of Fe single-atom catalyst(Fe-SAC)and Fe dual-atom catalyst(Fe-DAC)active sites at the interior of graphene and the edges of graphitic nanopore by using a combination of DFT calculations and microkinetic *** trend of limiting potentials for CO_(2)RR to produce CO can be described by using either the adsorption energy of COOH,CO,or their ***_(2)RR process with reasonable reaction rates can be achieved only on the active site configurations with weak tendencies toward CO *** efficiency of CO_(2)RR on a catalyst depends on its ability to suppress the parasitic hydrogen evolution reaction(HER),which is directly related to the behavior of H adsorption on the catalyst’s active *** find that the edges of the graphitic nanopore can act as potential adsorption sites for an H atom,and in some cases,the edge site can bind the H atom much stronger than the main Fe *** linear scaling between CO and H adsorptions is broken if this condition is *** condition also allows some edge active site configurations to have their CO_(2)RR limiting potential lower than the HER process favoring CO production over H2 production.

关键词： CO_(2)RR FexNy active site Fe-SAC Fe-DAC Graphitic edges DFT Microkinetic

Enhanced production of hydrogen via catalytic methane decomposition on a Pt_(7)-Ni(110)substrate:a reactive molecular dynamics investigation

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Clean Energy 2024年第2期8卷 168-176页

作者： Rizal arifin Zulkarnain Abdurrouf Yoyok Winardi Didik Riyanto Darminto Department of Mechanical Engineering Universitas Muhammadiyah PonorogoJl.Budi Utomo No.10Ponorogo63471Indonesia Department of Electrical Engineering Universitas Muhammadiyah PonorogoJl.Budi Utomo No.10Ponorogo63471Indonesia Department of Physics Education Universitas Muhammadiyah MataramJl.K.H.Ahmad Dahlan No.1Mataram83115Indonesia Department of Physics Brawijaya UniversityJl.VeteranMalang65145Indonesia Department of Physics Institut Teknologi Sepuluh NopemberKampus ITS SukoliloSurabaya60111Indonesia

Numerous researchers in the energy field are engaged in a competitive race to advance hydrogen as a clean and environmentally friendly *** have been conducted on the different aspects of hydrogen,including its production,storage,transportation and *** catalytic methane decomposition technique for hydrogen production is an environmentally friendly process that avoids generating carbon dioxide gas,which contributes to the greenhouse *** play a crucial role in facilitating rapid,cost-effective and efficient production of hydrogen using this *** this study,reactive molecular dynamics simulations were employed to examine the impact of Pt7 cluster decoration on the surface of a Ni(110)catalyst,referred to as Pt7-Ni(110),on the rates of methane dissociation and molecular hydrogen *** reactive force field was employed to model the atomic interactions that enabled the formation and dissociation of chemical *** reactive molecular dynamics simulations using the Pt7-Ni(110)catalyst revealed a notable decrease in the number of methane molecules,specifically~11.89 molecules per *** rate was approximately four times higher than that of the simulation system utilizing a Ni(110)catalyst and approximately six times higher than that of the pure methane,no-catalyst *** number of hydrogen molecules generated during a simulation period of 150000 fs was greater on the Pt7-Ni(110)surface than in both the Ni(110)and pure methane *** was due to the presence of numerous dissociated hydrogen atoms on the Pt7-Ni(110)surface.

关键词： hydrogen production catalytic methane decomposition reactive molecular dynamics Pt7 cluster Ni(110)

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

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

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

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