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Arctic sea-ice extent: No record minimum in 2023 or recent years

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Atmospheric and Oceanic Science Letters 2025年第1期18卷 52-55页

作者： Ola m.Johannessen Tor i.Olaussen Nansen Scientific Society BergenNorway Nansen Environmental and remote Sensing Center BergenNorway

Arctic sea-ice extent reaches its minimum each year in September. On 11 September 2023 the minimum was 4.969 million square kilometers(***^(2)). This was not a record low, which occurred in 2012, when the minimum was 4.175 ***^(2), 0.794 ***^(2) less than the minimum in 2023. However, the ice extent had decreased by 0.432 ***^(2) compared with 2022. Nevertheless, the summer melting in 2023 was remarkably less than expected when considering the strong heat waves in the atmosphere and ocean, with record temperatures set around the world. in general, there is a high correlation between the long-term decrease in sea-ice extent and the increasing CO_(2) in the atmosphere, where the increase of CO_(2) in recent decades explains about 80% of the decrease in sea ice in September, while the remainder is caused by natural variability.

关键词： Sea ice Arctic minimum ice Climate

Transportation of heat through Cattaneo-Christov heat flux model in non-Newtonian fluid subject to internal resistance of particles

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Applied mathematics and mechanics(English Edition) 2020年第8期41卷 1157-1166页

作者： m.i.khan F.ALZAHrANi Department of mathematics Riphah International UniversityFaisalabad 38000Pakistan Nonlinear Analysis and Applied mathematics(NAAm)-research Group Department of MathematicsFaculty of SciencesKing Abdulaziz UniversityJeddah 21589Saudi Arabia

Thermal conduction which happens in all phases(liquid,solid,and gas)is the transportation of internal energy through minuscule collisions of particles and movement of electrons within a working *** colliding particles comprise electrons,molecules,and atoms,and transfer disorganized microscopic potential and kinetic energy,mutually known as the internal *** engineering sciences,heat transfer comprises the processes of convection,thermal radiation,and sometimes mass ***,more than one of these procedures may happen in a given *** use the Cattaneo-Christov(CC)heat flux model instead of the Fourier law of heat conduction to discuss the behavior of heat transportation.A mathematical model is presented for the Cattaneo-Christov double diffusion(CCDD)in the flow of a non-Newtonian nanofluid(the Jeffrey fluid)towards a stretched *** magnetohydrodynamic(mHD)fluid is *** behaviors of heat and mass transportation rates are discussed with the *** models are based on Fourier’s and Fick’s *** convective transportation in nanofluids is discussed,subject to thermophoresis and Brownian *** nonlinear governing flow expression is first altered into ordinary differential equations via appropriate transformations,and then numerical solutions are obtained through the built-in-shooting *** impact of sundry flow parameters is discussed on the velocity,the skin friction coefficient,the temperature,and the concentration *** is reported that the velocity of material particles decreases with higher values of the Deborah number and the ratio of the relaxation to retardation time *** temperature distribution enhances when the Brownian motion and thermophoresis parameters *** concentration shows contrasting impact versus the Lewis number and the Brownian motion *** is also noticed that the skin friction coefficient decreases when the ratio of the relaxation to retarda

关键词： Cattaneo-Christov double diffusion(CCDD) non-Newtonian fluid model(Jeffrey model) viscous dissipation magnetohydrodynamic(mHD) Brownian diffusion thermophoresis diffusion

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

Enhancement of coercivity,permeability,and dielectric properties of Co_(0.2)Zn_(0.3)Ni_(0.5)Eu_(x)Fe_(2-x)O_(4) ferrites for memory and high frequency devices

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Journal of rare Earths 2024年第6期42卷 1128-1135,I0005页

作者： i.Sardar m.D.Hossain m.S.Sikder m.N.i.khan m.r.rahman Physics Discipline Khulna UniversityKhulna9208Bangladesh Department of Physics Khulna University of Engineering&TechnologyKhulna9203Bangladesh Department ofComputer Science and Engineering Northern University of Business&Technology KhulnaKhulna9100Bangladesh material Science Division Atomic Energy CentreDhaka1000Bangladesh

Spinel cubic ferrites have huge applications in me mory and high frequency *** the improvement of these modern devices,the magnetic coercivity,permeability,and dielectric properties of a ferrite are the important *** article focuses on improving the magnetic coercivity,magnetic permeability,and dielectric properties of Co_(0.2)Zn_(0.3)Ni_(0.5)Eu_(x)Fe_(2-x)O_(4) ferrites,where x=0.00,0.06,and *** X-ray diffraction(XrD),Fourier transform infrared spectroscopy(FTir),field emission scanning electron microscopy(FESEm),energy dispersive X-ray(EDX),vibrating sample magnetometer(VSm),and an impedance analyzer were used to characterize the structural,magnetic,and dielectric properties of the *** XrD patterns indicate the formation of spinel cubic structure of the samples with a secondary peak(EuFeO_(3))for Eu doped *** densities and porosities of the samples follow an inverse trend,where the doped samples’lattice parameters are increased with the increment of rare earth Eu *** FTir analysis also proves the spinel cubic phase of the *** average grain size of the ferrites is obtained via FESEm images,and it is increased from 121 to 198 *** analysis confirms that doping of the Eu content also changes other hysteresis loop properties of Co_(0.2)Zn_(0.3)Ni_(0.5)Eu_(x)Fe_(2-x)O_(4) ***,the coercivity of the Eu doped samples is greater than that of the mother alloy(x=0.00).The EDX study shows that there is no impurity contamination in the *** permeability and dielectric measurements show an improved quality factor of the Eu-doped samples with low magnetic and dielectric *** dependent resistivity and impedance analysis also show the improved *** the observed properties of the samples,all the investigated ferrites might be strong candidates for potential applications in memory devices,magnetic sensors,and high frequency applications.

关键词： Ferrites raree arths Coercivity Permeability EDX resistivity

monte-Carlo simulation of a stochastic differential equation

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Plasma Science and Technology 2017年第12期19卷 6-14页

作者： Arif ULLAH majid khan m KAmrAN r khan 盛正卯 Hefei National Laboratory for Physical Sciences at the microscale University of Science and Technology of ChinaHefei 230026People's Republic of China Department of Physics Quaid-i-Azam University islamabad Pakistan Department of Physics Institute of Fusion Theory and SimulationsZhejiang UniversityHangzhou 310027People's Republic of China Department of Physics COMSATS Institute of Information TechnologyChack ShahzadIslamabadPakistan Department of Physics Abdul Wali Khan University23200 MardanKPKPakistan

For solving higher dimensional diffusion equations with an inhomogeneous diffusion coefficient,monte Carlo（mC） techniques are considered to be more effective than other algorithms, such as finite element method or finite difference method. The inhomogeneity of diffusion coefficient strongly limits the use of different numerical techniques. For better convergence, methods with higher orders have been kept forward to allow mC codes with large step size. The main focus of this work is to look for operators that can produce converging results for large step sizes. As a first step, our comparative analysis has been applied to a general stochastic ***, our formulization is applied to the problem of pitch angle scattering resulting from Coulomb collisions of charge particles in the toroidal devices.

关键词： monte-Carlo simulation stochastic differential equations toroidal plasmas numerical methods

Copper ion Beam irradiation-induced Effects on Structural,morphological and Optical Properties of Tin Dioxide Nanowires

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Chinese Physics Letters 2016年第7期33卷 178-181页

作者： m.A.khan A.Qayyum i.Ahmed T.iqbal A.A.khan r.Waleed B.mohuddin m.malik Department of Physics University of Azad Jammu and Kashmir National Center of Physics Quaid-i-Azam University Campus UNESCO-UNiSA Africa Chair in Nanosciences/Nanotechnology College of Graduate StudiesUniversity of South Africa Nanosciences African Network iThemba LABS-National Research Foundation

The 0.8 me V copper （ Cu） ion beam irradiation-induced effects on structural, morphological and optical properties of tin dioxide nanowires （Sn02 NWs） are investigated. The samples are irradiated at three different doses 5 × 10^12 ions/cm2, 1 ×10^13 ions/cm2 and 5 × 10^13 ions/em2 at room temperature. The XrD analysis shows that the tetragonal phase of Sn02 NWs remains stable after Cu ion irradiation, but with increasing irradiation dose level the crystal size increases due to ion beam induced coalescence of NWs. The FTir spectra of pristine Sn02 NWs exhibit the chemical composition of SnO2 while the Cn-O bond is also observed in the FTir spectra after Cu ion beam irradiation. The presence of Cu impurity in SnO2 is further confirmed by calculating the stopping range of Cu ions by using Trm/Srim code. Optical properties of SnO2 NWs are studied before and after Cu ion irradiation. Band gap analysis revems that the band gap of irradiated samples is found to decrease compared with the pristine sample. Therefore, ion beam irradiation is a promising technology for nanoengineering and band gap tailoring.

关键词： of cm Copper ion Beam irradiation-induced Effects on Structural,morphological and Optical Properties of Tin Dioxide Nanowires in is that for been on

Heat Transfer Augmentation in Developing Flow Through a ribbed Square Duct

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Journal of Thermal Science 2006年第3期15卷 251-256页

作者： khan r K Ali m.A.T Akhanda m.A.r Principal Polytechnic InstitutePotuakhaliBangladesh Department of mechanical Engineering Bangladesh University of Engineering and Technology(BUET)DhakaBangladesh Department of mechanical and Chemical Engineering islamic University of Technology(iUT) OIC Gazipur-1704DhakaBangladesh

An experimental study is conducted to investigate the heat transfer augmentation in developing turbulent flow through a ribbed square duct. The duct is made of 16ram thick bakelite sheet. The bottom surface of the ribbed wall having rib pitch to height ratio of 10 is heated by passing a c current to the heater placed under it. The uniform heating is controlled using a digital temperature controller and a variac. The results of ribbed duct are compared with the results of a smooth duct under the same experimental conditions. it is observed that the heat transfer augmentation in ribbed duct is better than that of the smooth duct. At re=5.0× 10^4 , the mean temperature of air flowing through the ribbed duct increases by 2.45 percent over the smooth duct, whereas in the fibbed duct Nusselt number increases by 15.14 percent than that of the smooth duct with a 6 percent increase in pressure drop.

关键词： heat transfer square duct developing flow turbulent promoters

Entropy generation approach with heat and mass transfer in magnetohydrodynamic stagnation point flow of a tangent hyperbolic nanofluid

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Applied mathematics and mechanics(English Edition) 2021年第8期42卷 1205-1218页

作者： Tiehong ZHAO m.r.khan Yuming CHU A.iSSAKHOV r.ALi S.khan Department of mathematics Hangzhou Normal UniversityHangzhou 311121China LSEC and iCmSEC Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 1001900China School of mathematical Science University of Chinese Academy of SciencesBeijing 1001900China Department of mathematics Huzhou UniversityHangzhou 313000Zhejiang ProvinceChina Department of mathematical and Computer modeling Al-Farabi Kazakh National UniversityAlmaty 050040Kazakhstan Department of mathematical and Computer modeling Kazakh British-Technical UniversityAlmaty 050000Kazakhstan School of mathematics and Statistics Central South UniversityChangsha 410083China

This work examines the entropy generation with heat and mass transfer in magnetohydrodynamic(mHD)stagnation point flow across a stretchable *** heat transport process is investigated with respect to the viscous dissipation and thermal radiation,whereas the mass transport is observed under the influence of a chemical *** irreversibe factor is measured through the application of the second law of *** established non-linear partial differential equations(PDEs)have been replaced by acceptable ordinary differential equations(ODEs),which are solved numerically via the bvp4 c method(built-in package in mATLAB).The numerical analysis of the resulting ODEs is carried out on the different flow parameters,and their effects on the rate of heat transport,friction drag,concentration,and the entropy generation are *** is determined that the concentration estimation and the Sherwood number reduce and enhance for higher values of the chemical reaction parameter and the Schmidt number,although the rate of heat transport is increased for the Eckert number and heat generation/absorption parameter,*** entropy generation augments with boosting values of the Brinkman number,and decays with escalating values of both the radiation parameter and the Weissenberg number.

关键词： tangent hyperbolic fluid magnetohydrodynamic(mHD) viscous dissipation stagnation point flow heat generation/absorption thermal radiation

Exact solutions of mHD second Stokes flow of generalized Burgers fluid

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Applied mathematics and mechanics(English Edition) 2015年第2期36卷 211-224页

作者： m.khan r.mALiK A.ANJUm Department of mathematics Quaid-i-Azam University

This work concerns with the exact solutions of magnetohydrodynamic（mHD）flow of generalized Burgers fluid describing the second Stokes problem. The modified Darcy law is taken into account. The related velocity distribution and shear stress are expressed as a combination of steady-state and transient solutions computed by means of integral transformations. The effects of various parameters on the flow field are investigated. The mHD flow results in reduction of velocity distribution and associated thickness of the boundary layer.

关键词： generalized Burgers fluid magnetohydrodynamic(mHD) flow porous medium exact solution