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Analysis and Optimum Plan for 3-Step Step-Stress Accelerated Life Tests with Lomax model Under Progressive Type-i Censoring

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Communications in mathematics and Statistics 2018年第1期6卷 73-90页

作者： n.Chandra mashroor Ahmad khan Department of Statistics Pondicherry UniversityPuducherryIndia

inthispaper,theoptimumtestplanandparameterestimationfor3-stepstep-stress accelerated life tests in the presence of modified progressive Type-i censoring are *** is assumed that the lifetime of test units follows a Lomax distribution with log of characteristic life being quadratic function of stress *** maximum likelihood and Bayesian method are used to obtain the point and interval estimators of the model *** Bayes estimates are obtained using markov chain monte Carlo simulation based on Gibbs *** optimum plan for 3-step step-stress test under modified progressive Type-i censoring is developed which minimizes the asymptotic variance of the maximum likelihood estimators of log of scale parameter at design ***,the numerical study with sensitivity analysis is presented to illustrate the proposed study.

关键词： Accelerated life test Lomax distribution maximum likelihood estimation Bayesian estimation Progressive Type-i censoring

The development of ultralightweight expanded perlite-based thermal insulation panel using alkali activator solution

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Frontiers of Structural and Civil Engineering 2022年第11期16卷 1486-1499页

作者： Damla nur CELiK Gökhan DURmUŞ Civil Engineering Department Technology FacultyGazi UniversityAnkara 06500Turkey

The international Energy Agency(iEA)states that global energy consumption will increase by 53%by *** has 70%of the world’s perlite reserves,and in order to reduce energy consumption a thermal insulation panel was developed in Turkey using different particle sizes of expanded perlite(EP).in this study,0–1.18 mm(powder)and 0–3 mm(granular)EP particle sizes were selected,since they have the lowest thermal conductivity coefficients among all the particle *** addition,an alkali activator solution was used as a binder in the *** alkaline activator solution was obtained by mixing sodium hydroxide solution(6,8,10,and 12 mol·L−1)and sodium silicate(module 3)at the different ratios of na2SiO3 to naOH of 1,1.5,2,and *** study aimed to experimentally determine the optimum binder and distribution ratio of EP,with the lowest coefficient of thermal conductivity and the lowest *** lowest thermal conductivity and the lowest density were determined as 0.04919 W·m−1·K−1 and 133.267 kg/m3,respectively,in the sample prepared with 83.33%powder-size EP,6 mol·L−1 sodium hydroxide solution,and ratio of na2SiO3 to naOH of *** density,thermal conductivity,and compressive strength of the sample showed the same trends of behavior when the na2SiO3 to naOH ratio was *** addition,the highest compressive strength was measured in 12 mol·L−1 naOH concentration regardless of particle *** conclusion,the study predicts that the EP-based thermal insulation panel can be used as an insulation material in the construction industry according to the TS825 Thermal insulation Standard.

关键词： expanded perlite alkali activator thermal insulation panel thermal conductivity

multiparty Quantum Cryptographic Protocol

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Chinese Physics Letters 2008年第10期25卷 3543-3546页

作者： m. Ramzan m. K. khan Department of Physics Quaid-i-Azam University islamabad 45320 Pakistan

We propose a multiparty quantum cryptographic protocol. Unitary operators applied by Bob and Charlie, on their respective qubits of a tripartite entangled state encoding a classical symbol that can be decoded at Alice＇s end with the help of a decoding matrix. Eve＇s presence can be detected by the disturbance of the decoding matrix. Our protocol is secure against intercept resend attacks. Furthermore, it is eifficient and deterministic in the sense that two classical bits can be transferred per entangled pair of qubits. it is worth mentioning that in this protocol, the same symbol can be used for key distribution and Eve＇s detection that enhances the etfficiency of the protocol.

关键词： the power-law exponents precipitation durative abrupt precipitation change

Bioaccumulation of metals in human blood in industrially contaminated area

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Journal of Environmental Sciences 2011年第12期23卷 2069-2077页

作者： F. Akbar Jan m. ishaq S. khan m. Shakirullah S. m. Asim i. Ahmad Fazal mabood institute of Chemical Sciences University of Peshawar 25120 Khyber-Pukhtunkhwa Pakistan Department of Environmental Sciences University of Peshawar Peshawar Pakistan Department of Statistics University of Peshawar Peshawar Department of-Biological-Sciences ＆ Chemistry University of Nizwa Nizwa Oman

Heavy metals were analyzed in different foods crops, milk, meat and blood samples collected from different age group subjects such as children （1–12 years）, adolescent （12–18 years）, adults （18–45 years） and old age （above 45 and 55 years for males and females, respectively） from polluted and relatively less polluted areas. The results revealed that the consumption of contaminated food crops, meat and milk have significantly increased the concentrations of selected metals in the human blood. Cu, Zn and mn concentrations were significantly higher （p 0.05） in the blood samples collected from the polluted area as compared to control area. Old people had accumulated high concentrations of metals as compared to the younger ones within the same area. males accumulated higher concentrations of metals as compared to females.

关键词： bioaccumulation heavy metals blood contaminated meat milk forage grass

Transient flow of magnetized maxwell nanofluid: Buongiorno model perspective of Cattaneo-Christov theory

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Applied mathematics and mechanics(English Edition) 2020年第4期41卷 655-666页

作者： m.khan A.AHmED J.AHmED Department of mathematics Quaid-i-Azam UniversityIslamabad 44000Pakistan Department of Basic Sciences University of Engineering and TechnologyTaxila 47050Pakistan

The present research article is devoted to studying the characteristics of Cattaneo-Christov heat and mass fluxes in the maxwell nanofluid flow caused by a stretching sheet with the magnetic field *** maxwell nanofluid is investigated with the impact of the Lorentz force to examine the consequence of a magnetic field on the flow characteristics and the transport of *** heat and mass transport mechanisms in the current physical model are analyzed with the modified versions of Fourier’s and Fick’s laws,***,the well-known Buongiorno model for the nanofluids is first introduced together with the Cattaneo-Christov heat and mass fluxes during the transient motion of the maxwell *** governing partial differential equations(PDEs)for the flow and energy transport phenomena are obtained by using the maxwell model and the Cattaneo-Christov theory in addition to the laws of *** transformations are used to convert the PDEs into a system of nonlinear ordinary differential equations(ODEs).The homotopic solution methodology is applied to the nonlinear differential system for an analytic *** results for the time relaxation parameter in the flow,thermal energy,and mass transport equations are discussed *** is noted that higher values of the thermal and solutal relaxation time parameters in the Cattaneo-Christov heat and mass fluxes decline the thermal and concentration fields of the ***,larger values of the thermophoretic force enhance the heat and mass transport in the ***,the Brownian motion of the nanoparticles declines the concentration field and increases the temperature *** validation of the results is assured with the help of numerical tabular data for the surface velocity gradient.

关键词： transient flow Cattaneo-Christov theory maxwell nanofluid Buongiorno model homotopy analysis method (HAm) solution

Thermal analysis in swirl motion of maxwell nanofluid over a rotating circular cylinder

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Applied mathematics and mechanics(English Edition) 2020年第9期41卷 1417-1430页

作者： A.AHmED m.khan J.AHmED Department of mathematics Quaid-i-Azam UniversityIslamabad 44000Pakistan Department of Basic Sciences University of Engineering and TechnologyTaxila 47050Pakistan

in this paper,the mechanism of thermal energy transport in swirling flow of the maxwell nanofluid induced by a stretchable rotating cylinder is *** rotation of the cylinder is kept constant in order to avoid the induced axially secondary ***,the novel features of heat generation/absorption,thermal radiation,and Joule heating are studied to control the rate of heat *** effects of Brownian and thermophoretic forces exerted by the maxwell nanofluid to the transport of thermal energy are investigated by utilizing an effective model for the nanofluid proposed by *** whole physical problem of fluid flow and thermal energy transport is modelled in the form of partial differential equations(PDEs)and transformed into nonlinear ordinary differential equations(ODEs)with the help of the suitable flow *** acquired results through the technique bvp4c are reported graphically with physical *** analysis reveals that there is higher transport of heat energy in the maxwell nanoliquid for a constant wall temperature(CWT)as compared with the prescribed surface temperature(PST).Both thermophoretic and Brownian forces enhance the thermal energy transport in the flowing maxwell ***,the temperature distribution increases with increasing values of the radiation parameter and the Eckert *** is also noted that an increase in Reynolds number reduces the penetration depth,and as a result the flow and transport of energy occur only near the surface of the cylinder.

关键词： maxwell nanofluid rotating cylinder heat source/sink Joule heating convective condition numerical solution

numerical Analysis of the Behavior of A new Aeronautical Alloy (Ti555-03) Under the Effect of A High-Speed Water Jet

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China Ocean Engineering 2019年第1期33卷 114-126页

作者： i.Ben Belgacem L.Cheikh E.m.Barhoumi W.khan W.Ben Salem Laboratoire de Génie mécanique Ecole Nationale d’Ingénieurs de MonastirUniversité de Monastir institut Préparatoire aux Etudes d’ingénieur de monastir Université de Monastir Department of Electrical and Computer Engineering College of EngineeringDhofar University University of Waterloo institut Supérieur des Arts et métiers de mahdia Université de Monastir

in this paper, we present a numerical simulation of a water jet impacting a new aeronautical material Ti555-03 *** Computational Fluid Dynamics(CFD) behavior of the jet is investigated using a FV(Finite Volume) *** Fluid–Structure interaction(FSi) is studied using a coupled SPH(Smoothed Particle Hydrodynamics)-FE(Finite Element) method. The jets hit the metal sheet with an initial velocity 500 m/s. Two configurations which differ from each other by the position(angle of inclination) of the plate relatively to the axis of revolution of the jet inlet are investigated in this study. The objective of this study is to predict the impact of the fluid produced at high pressure and high speed especially at the first moment of impact. numerical simulations are carried out under ABAQUS. We have shown in this study that the inclination of the titanium alloy plate by 45° stimulates the phenomenon of recirculation of water. This affects the velocity profile, turbulence and boundary layers in the impact zone. The stagnation zone and the phenomenon of water recirculation are strongly influenced by the slope of the plate which gives a pressure gradient and displacement very important between the two configurations. Fluctuations of physical variables(displacement and pressure) prove the need for a noise and vibratory study. These predictions will subsequently be used for the modeling of the problem of an orthogonal cut in a high-speed machining process assisted by high-pressure water jet.

关键词： Titanium alloy(Ti555-03) CFD turbulence ABAQUS Smoothed Particle Hydrodynamics(SPH) Fluid Structure interaction(FSi)

High-temperature deformation behaviour of duplex stainless steel with hard boronised layer

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Journal of iron and Steel Research international 2021年第2期28卷 244-253页

作者： n.m.Sultan i.Jauhari R.Saidan m.F.m.Sabri Department of mechanical Engineering Faculty of EngineeringUniversity MalayaKuala Lumpur 50603Malaysia

in order to understand the high-temperature deformation behaviour of alloy having hard surface layer,thermo-mechanically treated duplex stainless steel(DSS)is boronised for 0.75-6 h at 1223 K and subsequently deformed under compression mode at the same temperature under strain rate condition of 1×10^(-3),2×10^(-4) and 6×10^(-5) s^(-1) until strain of *** substrate microstructure is almost isotropic with grain size after boronising with layer thickness between 1.61 and 2.74μm.X-ray diffraction results confirm the formation of boride on DSS *** surface hardness of DSS increases from 387 to 1000-2400 HV after *** boronised layer with thickness of 20-40μm is formed at DSS *** results show that the flow stress of the deformation increases with the strain rate and boronising *** the boronised samples,the flow stress range is between 5 and 89 *** determine the actual effect of the boronised layer on the flow stress,the results are also compared with those from un-boronised samples having similar *** results suggest that at a constant grain size,even with the hardest layer,the effect of hard surface layer on the flow stress almost could be negligible when the deformation rate is slow,but at faster deformation rate,even in the layer with the least hardness,the flow stress shows a significant *** is also observed that the hard boride surface disintegration could be avoided at a sufficiently low deformation flow stress that could be attributed to superplasticity.

关键词： High-temperature deformation Superplasticity Duplex stainless steel Hard boride layer Surface integrity Grain size effect Strain rate effect

Boundary layer flow of maxwell fluid due to torsional motion of cylinder: modeling and simulation

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Applied mathematics and mechanics(English Edition) 2020年第4期41卷 667-680页

作者： m.khan A.AHmED J.AHmED Department of mathematics Quaid-i-Azam UniversityIslamabad 44000Pakistan Department of Basic Sciences University of Engineering and TechnologyTaxila 47050Pakistan

This paper investigates the boundary layer flow of the maxwell fluid around a stretchable horizontal rotating cylinder under the influence of a transverse magnetic *** constitutive flow equations for the current physical problem are modeled and analyzed for the first time in the *** torsional motion of the cylinder is considered with the constant azimuthal velocity *** partial differential equations(PDEs)governing the torsional motion of the maxwell fluid together with energy transport are simplified with the boundary layer *** current analysis is valid only for a certain range of the positive Reynolds ***,for very large Reynolds numbers,the flow becomes ***,the governing similarity equations are simplified through suitable transformations for the analysis of the large Reynolds *** numerical simulations for the flow,heat,and mass transport phenomena are carried out in view of the bvp4c scheme in *** outcomes reveal that the velocity decays exponentially faster and reduces for higher values of the Reynolds numbers and the flow penetrates shallower into the free stream *** is also noted that the phenomenon of stress relaxation,described by the Deborah number,causes to decline the flow fields and enhance the thermal and solutal energy transport during the fluid *** penetration depth decreases for the transport of heat and mass in the fluid with the higher Reynolds *** excellent validation of the numerical results is assured through tabular data with the existing literature.

关键词： torsional motion maxwell fluid magnetic field stretchable rotating cylinder bvp4c scheme