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Applying the spectral stochastic finite element method in multiple-random field RC structures

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Frontiers of Structural and Civil Engineering 2022年第4期16卷 434-447页

作者： abbas YAZDANI Civil Engineering Department University of Sistan and BaluchestanZahedan 98167-45845Iran

this paper uses the spectral stochastic finite element method(SSFEM)for analyzing reinforced concrete(RC)beam/slab *** doing so,it presents a new framework to study how the correlation length of a random field(RF)with uncertain parameters will affect modeling uncertainties and reliability *** considers:1)different correlation lengths for uncertainty parameters,and 2)dead and live loads as well as the elasticity moduli of concrete and steel as a multi-dimensional RF in concrete *** show the SSFEM’s efficiency in the study of concrete structures and to evaluate the sensitivity of the correlation length effects in evaluating the reliability,two examples of RC beams and slabs have been *** to the results,the RF correlation length is effective in modeling uncertainties and evaluating reliabilities;the longer the correlation length,the greater the dispersion range of the structure response and the higher the failure probability.

关键词： uncertainty spectral stochastic finite element method correlation length reliability assessment reinforced concrete beam/slab

Significance of induced magnetic field and variable thermal conductivity on stagnation point flow of second grade fluid

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Journal of Central South University 2021年第11期28卷 3381-3390页

作者： A.A.KHAN S.ILYAS t.abbas R.ELLAHI Department of Mathematics and Statistics International Islamic UniversityIslamabad 44000Pakistan Departrment of Mathematics Division of Science and TechnologyUniversity of EducationLahore 54770Pakistan Fulbright Fellow Department of Mechanical Engineering University of California RiversideRiverside 92521USA

In this study,the stagnation point transport of second grade fluid with linear stretching under the effects of variable thermal conductivity is *** magnetic field impact is also *** nonlinear set of particle differential equations is converted into set of ordinary differential equations through appropriate *** resulting equations are then resolved by optimal homotopy analysis *** effect of pertinent parameters of interest on skin friction coefficient,temperature,induced magnetic field,velocity and local Nusselt number is inspected by generating appropriate *** numerical results,the built-in bvp4 c technique in computational software MAtLAB is used for the convergence and residual errors of obtained series *** is perceived that the induced magnetic field is intensified by increasing β.It can also be observed that skin friction coefficient enhances with increasing value of magnetic parameter depending on the stretching ratio a/*** the validness of the obtained results,a comparison has been made and an excellent agreement of current study with existing literature is found.

关键词： stagnation point variable thermal conductivity induced magnetic field second grade fluid

Hematological Alterations in an Eastern Sudanese Chronic Kidney Disease Patient Population

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Open Journal of Urology 2024年第6期14卷 359-367页

作者： Mohammed Omer Abaker Gibreel Sundus Kamal Ibrahim Wijdan Abdel Aziz Hassan Manar Yahia Mahjoub Leyla Mohammed Kheir Hamid Hibatellah Majzoub abbas Nuha Fouzi Mohammed Secretariat of Academic Affairs Port Sudan Ahlia University Port Sudan Sudan Department of Hematology and Immunohematology College of Graduate Studies Port Sudan Ahlia University Port Sudan Sudan

Background: Chronic Kidney Disease (CKD), associated with a slow and progressive loss of kidney function over a period of several years, is an important clinical disaster with an increasing rate of morbidity and mortality especially in the least developed countries. Many hematological parameters are thought to alter dramatically during the course of the disease. these include white blood cells, red blood cells, and platelets. Methods: We tried, retrospectively, to evaluate the peripheral blood hematological alterations in a group of patients undergoing hemodialysis in an eastern Sudan dialysis center to add local medical information. Results: Anemia (Low hemoglobin and hematocrit) was detected in 94% of the patients’ group. Mean Erythrocyte count (3.32vs.4.76 (×109/L)), Hemoglobin concentration (9.4vs.13 (g/dl)), Hematocrit (28.7vs.38.7 (L/L)) and platelet count (296 vs. 238 (×109/L)) were significantly lower in the patients’ group than in the control group (P-values Conclusion: Five out of eight studied parameters (Red cell count, hemoglobin, hematocrit, mean cell hemoglobin concentration, and platelets count) have shown a significant alteration in CKD patients. As the complete blood count (CBC) test is the most utilized test in clinical laboratory practice, these alterations may be considered as early indicators for CKD. Furthermore, all patients with CKD must be routinely checked for these alterations.

关键词： Chronic Kidney Disease Chronic Renal Failure Hematological Alterations CBC Eastern Sudan Hemodialysis

Characteristics of settling of dilute suspension of particles with different density at high Reynolds numbers

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Particuology 2021年第3期19卷 62-74页

作者： Ali abbas Zaidi Department of Mechanical and Process Engineering ETH Zurich8092 ZurichSwitzerland

Dilute suspension of particles with same density and size develops clusters when settle at high Reynolds number(≥250).It is due to particles entrapment in the wakes produced by upstream *** this work,this phenomenon is studied for suspension having particles with different densities by numerical *** particle-fluid interactions are modelled using immersed boundary method and inter-particle collisions are modelled using discrete element *** simulations,settling Reynolds number is always kept above 250 and the suspension solid volume fraction is nearly 0.1 *** particle density ratios(*** of heavy particles to lighter particles)equal to 4:1 and 2:1 and particles with same density are *** each density ratio,the percentage volume fraction of each particle density is nearly varied from 0.8 to *** characteristics such as microstructures of settling particle,average settling velocity and velocity fluctuations of settling particles are *** show that for different density particles settling characteristics of suspension is largely dominated by heavy *** the end of paper,the underlying physics is explained for the anomalies observed in simulation.

关键词： Particle clustering at high reynolds number Suspension with different density particles Particle microstructure due to settling Immersed boundary method

Unsteady three-dimensional MHD flow of the micropolar fluid over an oscillatory disk with Cattaneo-Christov double diffusion

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Applied Mathematics and Mechanics(English Edition) 2019年第10期40卷 1471-1486页

作者： A.RAUF S.A.SHEHZAD Z.abbas t.HAYAt Department of Mathematics COMSATS University Islamabad Sahiwal 57000 Pakistan Department of Mathematics The Islamia University of Bahawalpur Bahawalpur 63100 Pakistan Department of Mathematics Quiad-i-Azam University Islamabad 44000 Pakistan

Cattaneo-Christov heat and mass flux models are considered rather than Fourier and Fick laws due to the presence of thermal and concentration transport hyperbolic phenomena. the generalized form of the Navier-Stokes model is considered in hydromagnetic flow. three-dimensional (3D) unsteady fluid motion is generated by the periodic oscillations of a rotating disk. Similarity transformations are used to obtain the normalized fluid flow model. the successive over relaxation (SOR) method with finite difference schemes are accomplished for the numerical solution of the obtained partial differential non-linear system. the flow features of the velocity, microrotation, temperature, and concentration fields are discussed in pictorial forms for various physical flow parameters. the couple stresses and heat and mass transfer rates for different physical quantities are explained via tabular forms. For better insight of the physical fluid model, 3D fluid phenomena and two-dimensional (2D) contours are also plotted. the results show that the micropolar fluids contain microstructure having non-symmetric stress tensor and are useful in lubrication theory. Moreover, the thermal and concentration waves in Cattaneo-Christov models have a significance role in the laser heating and enhancement in thermal conductivity.

关键词： three-dimensional (3D) flow micropolar fluid magnetohydrodynamics (MHD) Cattaneo-Christov theory oscillatory disk

Photocatalytic degradation evaluation of N–Fe codoped aligned tiO2 nanorods based on the effect of annealing temperature

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Journal of Advanced Ceramics 2020年第1期9卷 107-122页

作者： abbas Sadeghzadeh-Attar Department of Metallurgy and Materials Engineering University of KashanP.O.Box.87317-53153Ghotb Ravandi Blvd.KashanIran

In this paper,a comparative study on the photocatalytic degradation of the Rhodamine B(Rh B)dye as a model compound using N–Fe codoped ti O2 nanorods under UV and visible-light(λ≥420 nm)irradiations has been *** O2 photocatalysts were fabricated as aligned nanorod arrays by liquid-phase deposition process,annealed at different temperatures from 400 to 800℃.the effects of annealing temperature on the phase structure,crystallinity,BEt surface area,and resulting photocatalytic activity of N–Fe codoped ti O2 nanorods were also *** degradation studies confirmed that the nanorods annealed at 600℃composed of both anatase(79%)and rutile phases(21%)and offered the highest activity and stability among the series of nanorods,as it degraded 94.8%and 87.2%Rh B in 120 min irradiation under UV and visible-light,*** 600℃,the photocatalytic performance of nanorods decreased owning to a phase change,decreased surface area and bandgap,and growth of ti O2 crystallites induced by the annealing *** is hoped that this work could provide precious information on the design of 1 D catalyst materials with more superior photodegradation properties especially under visible-light for the further industrial applications.

关键词： N–Fe codoped tiO2 nanorods liquid-phase deposition annealing temperature photocatalytic degradation

Centrifuge experiments for shallow tunnels at active reverse fault intersection

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Frontiers of Structural and Civil Engineering 2020年第3期14卷 731-745页

作者： Mehdi SABAGH abbas GHALANDARZADEH School of Civil Engineering University College of EngineeringUniversity of TehranTehran 11155-4563Iran

tunnels extend in large stretches with continuous lengths of up to hundreds of kilometers which are vulnerable to faulting in earthquake-prone *** the interaction of soil and tunnel at an intersection with an active fault during an earthquake can be a beneficial guideline for tunnel design ***,a series of 4 centrifuge tests are planned and tested on continuous ***-slip suface faulting in reverse mechanism of 60°is modeled by a fault simulator box in a quasi-static *** mechanism,progression and locations of damages to the tunnels are assessed through a gradual increase in Permanent Ground Displacement(PGD).the ground surface deformations and strains,fault surface trace,fault scarp and the sinkhole caused by fault movement are observed *** ground surface deformations are major threats to stability,safety and serviceability of the *** to the observations,the modeled tunnels are vulnerable to reverse fault rupture and but the functionality loss is not abrupt,and the tunnel will be able to tolerate some fault *** monitoring the progress of damage states by increasing PGD,the fragility curves corresponding to each damage state were plotted and interpreted in related figures.

关键词： reverse fault rupture continuous tunnel geotechnical centrifuge ground surface deformations fragility curves

Generalized thermoelastic interaction in functional graded material with fractional order three-phase lag heat transfer

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Journal of Central South University 2015年第5期22卷 1606-1613页

作者： Ibrahim A.abbas Department of Mathematics Faculty of Science and Arts - Khulais University of Jeddah Nonlinear Analysis and Applied Mathematics Research Group (NAAM) Department of MathematicsKing Abdulaziz University Department of Mathematics Faculty of Science Sohag University

the present work is concerned with the solution of a problem on thermoelastic interactions in a functional graded material due to thermal shock in the context of the fractional order three-phase lag model. the governing equations of fractional order generalized thermoelasticity with three-phase lag model for functionally graded materials(FGM)(i.e., material with spatially varying material properties) are established. the analytical solution in the transform domain is obtained by using the eigenvalue *** inversion of Laplace transform is done numerically. the graphical results indicate that the fractional parameter has significant effects on all the physical quantities. thus, we can consider the theory of fractional order generalized thermoelasticity an improvement on studying elastic materials.

关键词： three-phase lag model fimctionally graded materials fractional calculus generalized thermoelasticity

Sound waves in fluidized bed using CFD-DEM simulations

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Particuology 2018年第3期16卷 126-133页

作者： Hassan abbas Khawaja Process and Gas Group Department of Engineering & Safety UiT-The Arctic University of Norway 9037 Langnes Tromso Norway

the speed of sound waves in a fluidized bed is investigated using CFD-DEM numerical simulations, Appro- priate initial and boundary conditions are applied to reproduce bed phenomena. the effect of varying the height of the bed is also studied. the results of the simulations matched those from the literature. the pressure and particle velocity profiles obtained feature oscillatory behavior to which functions （based on a damped standing wave） were fitted, enabling an explicit dependence on time and space variables to be established. these fitted functions were substituted into the linearized governing equations for the two-phase flow. these solutions enabled a new relationship to be derived for the speed of sound and damping in the system. the conclusion drawn is tbat the damping in the system is governed by the effective bulk viscosity of the solid phase, which arises from the particle viscosity.

关键词： Fluidized bed Sound waves Speed of sound Damping time CFD-DEM simulations