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One-step synthesis route of the aligned and non-aligned single crystalline α-si_3N_4 nanowires

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science China(Technological sciences) 2009年第1期52卷 1-5页

作者： shkoor ahmad Beijing National Center for Electron Microscope Laboratory Department of Materials Science and Engineering Tsinghua University

This paper reports the bulk synthesis route of the aligned and non-aligned high-quality α-si_3N_4 nanowires (NWs) which were grown directly from the si substrate by vapor phase deposition at 1050℃. The as-grown products were characterized by employing XRD, sEM, HRTEM and photoluminescence. The microscopic results revealed that the products consist of single crystalline aligned and nonaligned α-si_3N_4 NWs having a same diameter range of 30-100 nm and different lengths of about hundreds of microns. The XRD observation revealed that the products consist of α-phase si_3N_4 NWs. The room temperature PL spectra indicated that the NWs have good emission property. The non-aligned NWs were formed at lower temperature as compared with aligned NWs. Our method is a simple and one-step procedure to synthesize the bulk-quantity and high-purity aligned and non-aligned α-si_3N_4 NWs at a relatively low temperature. The possible growth mechanism was also briefly discussed.

关键词： si_3N_4 nanowires aligned non-aligned crystalline

Effect of pressure on the electrical properties of flexible NiPc thin films fabricated by rubbing-in technology

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Chinese Physics B 2021年第1期30卷 328-331页

作者： Khasan s Karimov Fahmi F Muhammadsharif Zubair ahmad M Muqeet Rehman Rashid Ali GIK Institute of Engineering sciences and Technology TopiDistrict SwabiKPK23640Pakistan Center for Innovative Development of science and New Technologies of Academy of sciences of Tajikistan Dushanbe734025 Department of Physics Faculty of Science and HealthKoya University44023 KoyaKurdistan Region-F.R.Iraq Center for Advanced Materials(CAM) Qatar UniversityP.O.Box 2713DohaQatar Department of Electronic Engineering Jeju National UniversityJejuRepublic of Korea

Nickel phthalocyanine(Ni Pc) film was deposited onto the surface of flexible conductive glass by rubbing-in technology and used to fabricate devices based on ITO/Ni Pc/CNT/rubber structure. The I–V characteristics of the devices were investigated under different uniaxial pressures of 200, 280, and 480 gf/cm^(2), applied perpendicular to the surface of the Ni Pc film. Results showed that the nonlinearity coefficients of the I–V curves are in the range of 2 to 3, which was found to be decreased with the increase of the pressure. The rectification ratio of the devices was estimated to be varied from 1.5 to 3 based on the applied pressure. Concluding, the resistance of the active layers was decreased with the increase of both pressure and voltage. We believe that using the rubbing-in technology under sufficient applied pressure it is possible to utilize Ni Pc for the development of various electronic devices such as diodes, nonlinear resistors, and sensors.

关键词： pressure electrical property NiPc thin film rubbing-in technology

Dual-wavelength Q-switched erbium-doped fiber laser using an sMF-MMF-sMF structure and graphene oxide

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Optoelectronics Letters 2022年第11期18卷 668-672页

作者： s.F.s.M.Noor B.A.ahmad A.H.A.Rosol H.ahmad R.Apsari s.W.Harun Deparment of Physics Faculty of ScienceUniversity of MalayaKuala Lumpur 50603Malaysia Department of Communication Engineering Al-Ma'moon University CollegeBaghdad 700921Iraq Photonics Engineering Laboratory Department of Electrical EngineeringUniversity of MalayaKuala Lumpur 50603Malaysia Department of Engineering Faculty of Advanced Technology and MultidisciplineAirlangga UniversitySurabayaIndonesia Photonics Research Center University of MalayaKuala Lumpur 50603Malaysia Department of Physics Faculty of Science and TechnologyAirlangga UniversitySurabayaIndonesia

We have successfully demonstrated a stable dual-wavelength Q-switched erbium-doped fiber laser(EDFL) using a single mode fiber-multimode fiber-single mode fiber(sMF-MMF-sMF) structure-based filter. Using a graphene oxide(GO) saturable absorber(sA) to modulate the cavity loss, passive Q-switching of the dual-wavelength laser is achieved at 1 549.6 nm and 1 558.6 nm. The laser recorded the shortest pulse width of about 2.9 μs, the maximum pulse repetition rate of 65.27 kHz and the maximum average output power of 0.99 mW at pump power of 225.1 mW. The present laser has the maximum pulse energy of 15.17 nJ. A 2 sMF-MMF-sMF structure has been experimentally confirmed to be very promising as a wavelength filter.

关键词： fiber switched laser

Multi-wavelength erbium-doped fiber laser using four-wave mixing effect in doped fiber

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Chinese Optics Letters 2011年第6期9卷 80-81页

作者： N. s. shahabuddin Z. Yusoff H. ahmad s. W. Harun Department of Electrical Engineering University of Malaya Faculty of Engineering Multimedia University Photonics Research Center University of Malaya

We demonstrate a multi-wavelength erbium-doped fiber laser （EDFL） using erbium gain and four-wave mixing （FWM） effect in a piece of erbium-doped fiber （EDF） with high erbium ion concentration. The EDF has a pump absorption rate of 24.6 dB/m at 979 nm and is bi-directionally pumped by 980-nm laser diodes. FWM effect redistributes the energy of different oscillating lines and causes multi-wavelength operation. The laser generates more than 22 lines of optical comb with a line spacing of approximately 0.10 nm at the 1569-nm region using only 1.5-m-long EDF.

关键词： EDF FWM Multi-wavelength erbium-doped fiber laser using four-wave mixing effect in doped fiber length wave

Morphotectonic and Lithostratigraphic Analysis of Intermontane Karewa Basin of Kashmir Himalayas,India

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Journal of Mountain science 2013年第1期10卷 1-15页

作者： Reyaz ahmad DAR Rakesh CHANDRA shakil ahmad ROMsHOO Department of Earth sciences The University of Kashmir

Morpho-tectonic study plays an important role in deciphering the effects of tectonic activity in the geomorphic evolution of the drainage *** watershed forms one of the major watersheds of the intermontane Karewa Basin of Kashmir *** Karewa sediments are characterized by glacio-fluvio-lacustrine deposits capped by the aeolian *** geomorphic,morphometric and lithostratigraphic studies of these cap deposits have been carried out to elucidate the effect of tectonics on the geomorphic evolution of Romushi *** mapping was carried out using GPs measurements,DEM at 30m resolution,Topographic Position Index(TPI) model,topographic maps,LANDsAT TM Imagery and field *** and morphotectonic analyses in GIs environment were used to calculate various geomorphic indices(Mountain Front sinuosity Index,Bifurcation Ratio,Asymmetry Factor,River Profile,etc).These indices reveal that the tectonic uplift observed in the region due to Himalayan orogeny coupled with mass movement and aeolian deposition have dominated the landscape evolution of intermontane Karewa Basin of Kashmir throughout the Late Quaternary *** data from lithostratigraphic measurements were analyzed to understand the geomorphic evolution of intermontane Karewa *** data revealed that the basin has experienced differential uplift and erosion rates from time to time in the geological *** was corroborated by the results from the morphometric and morphotectonic analysis.

关键词： Himalayas Morphometry Watershed Morphotectonics Intermontane basin Remote sensing Drainage basin Digital elevation model

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

J/ψ-J/ψ scattering cross sections of quadratic and Cornell potentials

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Chinese Physics C 2021年第2期45卷 126-132页

作者： M.Imran Jamil sM.sohail Gilani ahmad Wasif Abdul sattar Khan ahmad Awan Department of Physics School of ScienceUniversity of Management and TechnologyLahore(54770)Pakistan Department of Physics University of OkaraOkara(56300)Pakistan Department of Physics Forman Christian College(A Chartered University)Lahore(54600)Pakistan Department of Physics Government College UniversityLahore(54000)Pakistan

We study the scattering of J/ψ - J/ψ mesons using quadratic and Cornell potentials in our tetraquark(cccc)*** system’s wavefunction in the restricted gluonic basis,which is written by utilizing the adiabatic approximation and Hamiltonian,is used via a quark potential *** resonating group technique is used to obtain the integral equations,which are solved to obtain the unknown inter-cluster dependence of the total wavefunction of our tetraquark system.T-Matrix elements are calculated from the solutions,and eventually,the scattering cross sections are obtained using the two *** compare these cross sections and find that the magnitudes of scattering cross sections of quadratic potential are higher than the Cornell potential.

关键词： Cornell potential quadratic potential J/ψscattering quark potential model

Influence of accelerated curing on the compressive strength of polymer-modified concrete

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Frontiers of structural and Civil Engineering 2022年第5期16卷 589-599页

作者： Izhar ahmad Kashif Ali KHAN Tahir ahmad Muhammad ALAM Muhammad Tariq BAsHIR College of Civil and Transportation Engineering Hohai UniversityNanjing 210098China Department of Civil Engineering Muslim Youth UniversityIslamabad 44000Pakistan Department of Civil Engineering CECOS University of IT&Emerging SciencesPeshawar 25000Pakistan Department of Civil Engineering University of Engineering&TechnologyMardan 23200Pakistan

In recent building practice,rapid construction is one of the principal ***,in designing concrete structures,compressive strength is the most significant of all *** 3-d and 7-d compressive strength reflects the strengths at early phases,the ultimate strength is *** effort has been made in this study to develop mathematical models for predicting compressive strength of concrete incorporating ethylene vinyl acetate(EVA)at the later ***-smirnov(Ks)goodness-of-fit test was used to examine distribution of the *** compressive strength of EVA-modified concrete was studied by incorporating various concentrations of EVA as an admixture and by testing at ages of 28,56,90,120,210,and 365 *** accelerated compressive strength at 3.5 hours was considered as a reference strength on the basis of which all the specified strengths were predicted by means of linear regression *** on the results of Ks goodness-of-fit test,it was concluded that Ks test statistics value(D)in each case was lower than the critical value 0.521 for a significance level of 0.05,which demonstrated that the data was normally *** on the results of compressive strength test,it was concluded that the strength of EVA-modified specimens increased at all ages and the optimum dosage of EVA was achieved at 16%***,it was concluded that predicted compressive strength values lies within a 6%difference from the actual strength values for all the mixes,which indicates the practicability of the regression *** research work may help in understanding the role of EVA as a viable material in polymer-based cement composites.

关键词： compressive strength prediction polymer-modified concrete linear regression fit early age strength ethylene vinyl acetate

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Post-annealing effect on the structural and mechanical properties of multiphase zirconia films deposited by a plasma focus device

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Chinese Physics B 2013年第12期22卷 442-450页

作者： I.A.Khan R.s.Rawat R.ahmad M.A.K.shahid Department of Physics Government College University National Institute of Education Nanyang Technological University Department of Physics GC University

Nanostructured multiphase zirconia films （MZFs） are deposited on Zr substrate by the irradiation of energetic oxygen ions emanated from a plasma focus device. The oxygen operating gas pressure of 1 mbar （1 bar=105 Pa） provides the most appropriate ion energy flux to deposit crystalline ZrO2 films. X-ray diffraction （XRD） patterns reveal the formation of polycrystalline ZrO2 films. The crystallite size （Cs）, crystal growth, and dislocation densities are attributed to increasing focus shots, sample axial distances, and working gas pressures. Phase and orientation transformations from t-ZrO2 to m-ZrO2 and c-ZrO2 are associated with increasing focus shots and continuous annealing. For lower （200 ℃） annealing temperature （AT）, full width at half maximum （FWHM） of diffraction peak, Cs, and dislocation density （δ） for （020） plane are found to be 0.494, 16.6 nm, and 3.63×10-3 nm-2 while for higher （400 ℃） AT, these parameters for （111） plane are found to be 0.388, 20.87 nm, and 2.29×10-3 nm-2, respectively. scanning electron microscope （sEM） results demonstrate the formation of rounded grains with uniform distribution. The estimated values of atomic ratio （O/Zr） in ZrO2 films deposited for different axial distances （6 cm, 9 cm, and 12 cm） are found to be 2.1, 2.2, and 2.3, respectively. Fourier transform infrared （FTIR） analysis reveals that the bands appearing at 441 cm-1 and 480 cm-1 belong to m-ZrO2 and t-ZrO2 phases, respectively. Maximum microhardness （8.65±0.45 GPa） of ZrO2 film is ～ 6.7 times higher than the microhardness of virgin Zr.

关键词： zrconia phase transformation XRD sEM Fourier transform infrared analysis