检索结果-南通市图书馆

Weak gravity conjecture from conformal field theory:a challenge from hyperscaling violating and Kerr-Newman-AdS black holes

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2023年第1期47卷 225-233页

作者： jafar sadeghi Mehdi Shokri Mohammad Reza Alipour Saeed Noori Gashti Department of Physics University of MazandaranP.0.Box 47416-95447BabolsarIran School of Physics Damghan UniversityP.0.Box ***DamghanIran Department of Physics University of TehranNorth Karegar Ave.Tehran 14395-547ran Canadian Quantum Research Center 204-300232 Avenue Vernon British Columbia V1T 2L7Canada

We search for a possible relationship between weak gravity conjecture(WGC)and conformal field theory(CFT)in hyperscaling violating and Kerr-Newman-AdS black holes.We deal with the critical points of the black hole systems using the correlation function introduced in CFT and discuss WGC conditions using the imaginary part of the energy obtained from the critical points and their poles.Under the assumptions z=1,d=1,andθ→0-,we link WGC to hyperscaling violating black holes owing to the existence of rHvalues larger and smaller than one.For the second black hole system,we study the conditions of WGC for Kerr-Newman-AdS black holes using rotation and radius parameters.Then,we show that the conditions of WGC are satisfied when the charged particle near the hyperscaling violating and Kerr-Newman black holes is 1/a with a ratio a/l《1.

关键词： weak gravity conjecture Kerr-Newman-AdS black holes hyperscaling violating black holes conformal field theory

Darboux Transformation in Quantum Black-Scholes Hamiltonian and Supersymmetry

在线全文

学校读者我要写书评

暂无评论

Open Journal of Microphysics 2013年第2期3卷 43-46页

作者： jafar sadeghi Mohammad Rostami Ahmad Pourdarvish Behnam Pourhassan Department of Physics Imam Hossein University Tehran Iran Department of Physics Islamic Azad University—Ayatollah Amoli Branch Amol Iran Department of Statistics Mazandaran University Babolsar Iran

In this paper, we consider the Black-Scholes (BS) equation for option pricing with constant volatility. Here, we construct the first-order Darboux transformation and the real valued condition of transformed potential for BS corresponding equation. In that case we also obtain the transformed of potential and wave function. Finally, we discuss the factorization method and investigate the supersymmetry aspect of such corresponding equation. Also we show that the first order equation is satisfied by commutative algebra.

关键词： Black-Scholes Hamiltonian Darboux Transformation Supersymmetry

A review of control strategies used for morphing aircraft applications

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第4期37卷 436-463页

作者： Muhammed S.PARANCHEERIVILAKKATHIL jafar S.PILAKKADAN Rafic M.AJAJ Mohammadreza AMOOZGAR Davood ASADI Yahya ZWEIRI Michael I.FRISWELL Department of Aerospace Engineering Khalifa University of Science and TechnologyAbu DhabiUnited Arab Emirates Department of Aerospace Engineering Advanced Research and Innovation Center(ARIC)Khalifa University of Science and TechnologyAbu DhabiUnited Arab Emirates Department of Mechanical Materials&Manufacturing EngineeringUniversity of NottinghamNottingham NG72RDUK Department of Aerospace Engineering Adana Alparslan Turkes Science and Technology UniversityTurkey College of Engineering Swansea UniversitySwansea SA18ENUK

This paper reviews the various control algorithms and strategies used for fixed-wing morphing aircraft applications. It is evident from the literature that the development of control algorithms for morphing aircraft technologies focused on three main areas. The first area is related to precise control of the shape of morphing concepts for various flight conditions. The second area is mainly related to the flight dynamics, stability, and control aspects of morphing aircraft. The third area deals mainly with aeroelastic control using morphing concepts either for load alleviation purposes and/or to control the instability boundaries. The design of controllers for morphing aircraft/wings is very challenging due to the large changes that can occur in the structural, aerodynamic, and inertial characteristics. In addition, the type of actuation system and actuation rate/speed can have a significant effect on the design of such controllers. The aerospace community is in strong need of such a critical review especially as morphing aircraft technologies move from fundamental research at a low Technology Readiness Level(TRL) to real-life applications. This critical review aims to identify research gaps and propose future directions. In this paper, research activities/papers are categorized according to the control strategy used. This ranges from simple Proportional Integral Derivative(PID) controllers at one end to complex robust adaptive controllers and deep learning algorithms at the other end. This includes analytical, computational, and experimental studies. In addition, the various dynamic models used and their fidelities are highlighted and discussed.

关键词： Control strategies Morphing aircraft Shape morphing Flight dynamics Aeroelasticity

Toward a comprehensive hypothesis of oxygen-evolution reaction in the presence of iron and gold

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2024年第2期89卷 172-183,I0005页

作者： Negah Hashemi jafar Hussain Shah Cejun Hu Subhajit Nandy Pavlo Aleshkevych Sumbal Farid Keun Hwa Chae Wei Xie Taifeng Liu Junhu Wang Mohammad Mahdi Najafpour Department of Chemistry Institute for Advanced Studies in Basic Sciences(IASBS)Zanjan 45137-66731Iran Center for Advanced Mössbauer Spectroscopy Mössbauer Effect Data CenterDalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina Key Lab of Advanced Energy Materials Chemistry(Ministry of Education) Renewable Energy Conversion and Storage CenterCollege of ChemistryNankai UniversityTianjin 300071China Advanced Analysis Center Korea Institute of Science and TechnologySeoul 02792Republic of Korea Institute of Physics Polish Academy of SciencesWarsaw 02-668Poland National and Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials Henan UniversityKaifeng 475004HenanChina Center of Climate Change and Global Warming Institute for Advanced Studies in Basic Sciences(IASBS)Zanjan 45137-66731Iran Research Center for Basic Sciences&Modern Technologies(RBST) Institute for Advanced Studies in Basic Sciences(IASBS)Zanjan 45137-66731Iran

This study investigates the effects of Fe on the oxygen-evolution reaction(OER)in the presence of Au.Two distinct areas of OER were identified:the first associated with Fe sites at low overpotential(~330 mV),and the second with Au sites at high overpotential(~870 mV).Various factors such as surface Fe concentration,electrochemical method,scan rate,potential range,concentration,method of adding K_(2)Fe O_(4),nature of Fe,and temperature were varied to observe diverse behaviors during OER for Fe O_(x)H_(y)/Au.Trace amounts of Fe ions had a significant impact on OER,reaching a saturation point where the activity did not increase further.Strong electronic interaction between Fe and Au ions was indicated by X-ray photoelectron spectroscopy(XPS)and electron paramagnetic resonance(EPR)analyses.In situ visible spectroscopy confirmed the formation of Fe O_(4)^(2-)during OER.In situ Mossbauer and surfaceenhanced Raman spectroscopy(SERS)analyses suggest the involvement of Fe-based species as intermediates during the rate-determining step of OER.A lattice OER mechanism based on Fe O_(x)H_(y)was proposed for operation at low overpotentials.Density functional theory(DFT)calculations revealed that Fe oxide,Fe-oxide clusters,and Fe doping on the Au foil exhibited different activities and stabilities during OER.The study provides insights into the interplay between Fe and Au in OER,advancing the understanding of OER mechanisms and offering implications for the design of efficient electrocatalytic systems.

关键词： DFT calculation Fe/Au electrocatalysis Mechanism Oxygen evolution Water oxidation

Feasibility of a novel beamforming algorithm via retrieving spatial harmonics

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2022年第1期33卷 38-46页

作者： NOROLAHI jafar AZMI Paeiz NASIRIAN Mahdi Electrical and Computer Engineering Department Tarbiat Modares UniversityTehran 14115Iran Department of Electrical and Computer Engineering Sharif University of TechnologyTehran 11365Iran

This paper introduces an algorithm for beamforming systems by the aid of multidimensional harmonic retrieval(MHR).This algorithm resolves problems,removes limitations of sampling and provides a more robust beamformer.A new sample space is created that can be used for estimating weights of a new beamforming called spatial-harmonics retrieval beamformer(SHRB).Simulation results show that SHRB has a better performance,accuracy,and applicability and more powerful eigenvalues than conventional beamformers.A simple mathematical proof is provided.By changing the number of harmonics,as a degree of freedom that is missing in conventional beamformers,SHRB can achieve more optimal outputs without increasing the number of spatial or temporal samples.We will demonstrate that SHRB offers an improvement of 4 dB in signal to noise ratio(SNR) in bit error rate(BER) of 10~(-4) over conventional beamformers.In the case of direction of arrival(DOA) estimation,SHRB can estimate the DOA of the desired signal with an SNR of-25 dB,when conventional methods cannot have acceptable response.

关键词： multi-input-multi-output(MIMO) beamforming spatial and temporal signal processing multidimensional harmonic retrieval(MHR) space-time signal processing array signal processing

Effects of operating parameters on oxidative coupling of methane over Na-W-Mn/SiO_2 catalyst at elevated pressures

在线全文

学校读者我要写书评

暂无评论

Journal of Natural Gas Chemistry 2011年第2期20卷 204-213页

作者： jafar Sadeghzadeh Ahari Mohammad Taghi sadeghi Saeed Zarrinpashne Process Simulation and Control Laboratory Chemical Engineering College Iran University of Science and Technology (IUST) Gas Research Division-Research Institute of Petroleum Industry (RIPI)

The effects of operating parameters on oxidative coupling of methane （OCM） over Na-W-Mn/SiO2 catalyst have been studied at elevated pressures of 0.2, 0.3 and 0.4 MPa under low gaseous hourly space velocity （GHSV） and low temperature conditions. Experimental results show that when the operating pressure is increased, C2＋ yield slightly decreases, while the maximum ratio of ethylene to ethane remains unchanged. Moreover, it has been found empirically that increase of pressure does not affect the catalyst behavior permanently, the catalyst recovers its original low pressure performance without hysteresis behavior by reducing the pressure. Under the investigated conditions, when oxygen is completely consumed, the increase of GHSV leads to improvement in C2 selectivity, while C3＋ and COx selectivities decrease slightly. The C2＋ selectivity increases by increase of nitrogen diluent in the feed, but the C3＋ hydrocarbons selectivities decrease with increase of nitrogen since it is possible that further dilution at high pressure may reduce the probability of collision between CH3 and C2＋ hydrocarbons. During the stability test at high pressure, the catalyst performance remains unchanged throughout the 20 h running. The fresh and used catalysts were characterized using XRD, SEM and N2 adsorption-desorption methods. It was found that the phase transformation of the support from α-cristobalite to tridymite and quartz does not have obvious effect on catalyst performance at high pressure.

关键词： operating parameters oxidative coupling of methane Na-W-Mn/SiO2 catalyst elevated pressure

Highly stable Ga-doped ZnO/polystyrene nanocomposite film with narrow-band cyan emission

在线全文

学校读者我要写书评

暂无评论

Journal of Semiconductors 2022年第12期43卷 46-54页

作者： Sanaz Alamdari Majid jafar Tafreshi Morteza Sasani Ghamsari Department of Nanotechnology Faculty of New Sciences and TechnologiesSemnan UniversitySemnan35131-19111Iran Faculty of Physics Semnan University35195-363SemnanIran Photonics&Quantum Technologies Research School Nuclear Science and Technology Research Institute11155-3486TehranIran

In the present study,a simple method for the preparation of a luminescent flexible gallium doped zinc oxide(GZO)/polystyrene nanocomposite film was developed.The prepared GZO powder was characterized through different optical and structural techniques.The XRD study revealed the existence of a wurtzite structure with no extra oxide peaks.Elemental-mapping,EDX,FTIR and XPS analyses were used to confirm the presence of elements and the several groups present in the structure.Under excitations of UV,the prepared hybrid nanocomposite showed a strong cyan emission with narrow full width at half the maximum value(20 nm)that has not been reported before.X-ray and laser-induced luminescence results of the hy-brid film revealed novel blue-green emission at room temperature.The prepared composite film showed a strong scintillation re-sponse to ionizing radiation.The strong emissions,very weak deep-level emissions,and low FWHM of composite indicate the de-sirable optical properties with low-density structural defects in the GZO composite structure.Therefore,the prepared hybrid film can be considered to be a suitable candidate for the fabrication of optoelectronic devices.

关键词： Ga doped ZnO cyan emission narrow-band emission nanocomposite

Rhizobacteria facilitate physiological and biochemical drought tolerance of Halimodendron halodendron (Pall.) Voss

在线全文

学校读者我要写书评

暂无评论

Journal of Arid Land 2023年第2期15卷 205-217页

作者： Mohammad Hossein TAGHIZADEH Mohammad FARZAM jafar NABATI Department of Range and Watershed Management Ferdowsi University of MashhadMashhad ***Iran Legume Department Research Center for Plant SciencesFerdowsi University of MashhadMashhad ***Iran

Growth-promoting bacteria(GPB)have shown promising effects on serving plants against environmental constraints such as drought.Nevertheless,simultaneous effects of different GPB have less been considered for arid land plants and under field conditions.We investigated the effects of single and combined application of GPB,including free-living nitrogen-fixing bacteria(NFB),phosphate solubilizing bacteria(PSB),potassium solubilizing bacteria(KSB),a combination of NFB,PSB,and KSB(NPK),and control,at three drought stress treatments.In order to better understand the interactions between drought and GPB,we measured the morphological,biochemical,and physiological plant traits.The target plant was salt tree(Halimodendron Halodendron(Pall.)Voss),a legume shrub native to arid lands of Central and West Asia.All biofertilizer treatments enhanced the growth,physiology,and biochemistry of salt tree seedlings,and there were significant differences among the treatments.KSB and PSB treatments increased photosynthetic pigments,but KSB treatment was more efficient in transpiration rate and stomatal regulation and increased the soluble carbohydrates.PSB treatment had the highest effect on root traits,such as taproot length,root volume,cumulative root length,and the ratio of root to shoot.NFB treatment enhanced root diameter and induced biomass translocation between root systems.However,only the application of mixed biofertilizer(i.e.,NPK treatment)was the most significant treatment to improve all plant morphological and physiological characteristics of salt tree under drought stress.Therefore,our results provided improvement of some specific plant traits simultaneous with application of three biofertilizers to increase growth and establishment of salt tree seedlings in the degraded arid lands.

关键词： growth-promoting bacteria physiological traits drought stress biofertilizer root traits Halimodendron Halodendron(Pall.)Voss

Robust low-rank learning multi-output regression for incipient sediment motion in sewer pipes

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2023年第6期38卷 859-870页

作者： Mir jafar Sadegh Safari Shervin Rahimzadeh Arashloo Department of Civil Engineering Yasar University Department of Computer Engineering Bilkent University

The existing incipient sediment motion models typically apply conventional regression methods considering either velocity or shear stress.In the current study,incipient sediment motion is analyzed through a simultaneous and joint analysis of velocity and shear stress using the robust low-rank learning(RLRL) multi-output regression technique.Moreover,the experimental data compiled from five different channels are utilized to develop a generic incipient sediment motion model valid for a channel of any cross-sectional shape.The efficiency of the developed method is examined and compared against the available conventional regression models.The experimental results indicate that the RLRL model yields better results than its counterparts.In particular,while cross-section specific models fail to provide accurate estimates for shear stress or velocity for other cross sections,the proposed model provides satisfactory results for all channel shapes.The better performance of the recommended approach can be attributed to the joint modeling of the shear stress and the velocity which is realized by capturing the correlation between these parameters in terms of a low rank output mixing matrix which enhances the prediction performance of the approach.

关键词： Low-rank learning Multi-output regression Sediment transport Sewer flow Shear stress approach Velocity approach