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Effects of temperature-dependent viscosity variation on entropy generation, heat and fluid flow through a porous-saturated duct of rectangular cross-section

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Applied Mathematics and Mechanics(English Edition) 2007年第1期28卷 69-78页

作者： k.hooman H.Gurgenci School of Engineering the University of Queensland Brisbane Australia

Effect of temperature-dependent viscosity on fully developed forced convection in a duct of rectangular cross-section occupied by a fluid-saturated porous medium is investigated analytically. The Darcy flow model is applied and the viscosity-temperature relation is assumed to be an inverse-linear one. The case of uniform heat flux on the walls, i.e. the H boundary condition in the terminology of kays and Crawford [12], is treated. For the case of a fluid whose viscosity decreases with temperature, it is found that the effect of the variation is to increase the Nusselt number for heated walls. Having found the velocity and the temperature distribution, the second law of thermodynamics is invoked to find the local and average entropy generation rate. Expressions for the entropy generation rate, the Bejan number, the heat transfer irreversibility, and the fluid flow irreversibility are presented in terms of the Brinkman number, the Péclet number, the viscosity variation number, the dimensionless wall heat flux, and the aspect ratio （width to height ratio）. These expressions let a parametric study of the problem based on which it is observed that the entropy generated due to flow in a duct of square cross-section is more than those of rectangular counterparts while increasing the aspect ratio decreases the entropy generation rate similar to what previously reported for the clear flow case by Ratts and Rant [14].

关键词： entropy generation rate forced convection porous medium rectangular duct temperature-dependent viscosity

Genetic algorithm optimization for finned channel performance

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Applied Mathematics and Mechanics(English Edition) 2007年第12期28卷 1597-1604页

作者： S.S.Mousavi k.hooman S.J.Mousavi Production Department SAIPA CompanyTehranIran School of Engineering the University of QueenslandBrisbaneAustralia knowledge Engineering Research Center Aerospace Industrial OrganizationTehranIran

Compared to a smooth channel, a finned channel provides a higher heat transfer coefficient; increasing the fin height enhances the heat transfer. However, this heat transfer enhancement is associated with an increase in the pressure drop. This leads to an increased pumping power requirement so that one may seek an optimum design for such systems. The main goal of this paper is to define the exact location and size of fins in such a way that a minimal pressure drop coincides with an optimal heat transfer based on the genetic algorithm. Each fin arrangement is considered a solution to the problem （an individual for genetic algorithm）. An initial population is generated randomly at the first step. Then the algorithm has been searched among these solutions and made new solutions iteratively by its functions to find an optimum design as reported in this article.

关键词： Nusselt number pressure drop genetic algorithm optimum design baffle

On the Relation Between Symmetry of Radio Galaxies and Their Physical Parameters

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Research in Astronomy and Astrophysics 2024年第9期24卷 37-59页

作者： Mohsen Javaherian Halime Miraghaei hooman Moradpour Research Institute for Astronomy and Astrophysics of Maragha(RIAAM) University of MaraghehP.O.Box 55136-553MaraghehIran

Gravity as a fundamental force plays a dominant role in the formation and evolution of cosmic objects and leaves its effect in the emergence of symmetric and asymmetric ***,analyzing the symmetry criteria allows us to uncover mechanisms behind the gravity interaction and understand the underlying physical processes that contribute to the formation of large-scale structures such as *** use a segmentation process using intensity thresholding and the k-means clustering algorithm to analyze radio galaxy *** employ a symmetry criterion and explore the relation between morphological symmetry in radio maps and host galaxy *** properties(stellar mass,black hole mass,optical size(R_(50)),concentration,stellar mass surface density(μ_(50)),and stellar age)and radio properties(radio flux density,radio luminosity,and radio size)are *** found that there is a correlation between symmetry and radio size,indicating larger radio sources have smaller symmetry ***,size of radio sources should be considered in any investigation of *** correlations are also observed with other properties,such as R_(50)for FRI galaxies and stellar *** compare the symmetry differences between FRI and FRII radio *** galaxies show higher symmetry in 1.4 GHz and 150 MHz *** the influence of radio source sizes,we discovered that this result is independent of the sizes of radio *** findings contribute to our understanding of the morphological properties and analyses of radio galaxies.

关键词： methods:data analysis techniques:image processing catalogs galaxies:nuclei galaxies:distances and redshifts

From non-scattering to super-scattering with Mie-tronics

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Photonics Research 2024年第4期12卷 608-624页

作者： hooman BARATI SEDEH NATALIA M.LITCHINITSER Department of Electrical and Computer Engineering Duke UniversityDurhamNorth Carolina 27708USA

Electric anapoles, arising from the destructive interference of primitive and toroidal electric dipole moments, have recently emerged as a fundamental class of non-scattering sources. On the other hand, super-scattering states represent the opposite regime wherein the scattering cross-section of a subwavelength particle exceeds the single-channel limit, leading to a strong scattering behavior. Here, we demonstrate that the interplay between the topology of light and the subwavelength scatterer can lead to these two opposite responses within an isolated alldielectric meta-atom. In particular, we present the emergence of a new non-scattering state, referred to as hybrid anapole, which surpasses conventional electric dipole anapoles by achieving a remarkable 23-fold enhancement in the suppression of far-field radiation and almost threefold enhancement in the confinement of electromagnetic energy inside the meta-atom. We also explore the role of particle orientation and its inversion symmetry in the scattering response and predict the possibility of switching between non-scattering and super-scattering states within the same platform. The presented study elucidates the role of light and matter topologies in the scattering response of subwavelength meta-atoms, uncovering two opposite regimes of light-matter interaction and opening new avenues in applications such as nonlinear optics and spectroscopy.

关键词： spectroscopy opposite dipole

Shoaling Internal Solitary Waves and the Formation of Boluses

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Open Journal of Fluid Dynamics 2024年第2期14卷 65-82页

作者： hooman Enayati Brian T. Helenbrook Department of Mechanical Engineering Lafayette College Easton PA USA Department of Mechanical & Aerospace Engineering Clarkson University Potsdam NY USA

An internal solitary wave of elevation in a two-layer density stratified system of an incompressible, viscous and homogeneous fluid was studied. The run-up of a wave of elevation encountering different slopes was investigated numerically based on solving the continuity, Navier-Stokes and convective-diffusion equations within the Boussinesq approximation. The commercial software COMSOL Multiphysics was used to conduct the numerical simulations. For gradual shoals, a bolus formed that transported dense fluid up the shoal. The bolus disappeared when it reached its maximum height on the slope due to the draining of the dense fluid. Various shoal angles were simulated to detect the critical angle above which a bolus does not form. An angle of 30 or less resulted in the formation of a bolus. In addition, the simulations demonstrated that the size of the bolus induced by shallower slopes was larger and that the vertical height traveled by the bolus was insensitive to the slope of the shoal.

关键词： Internal Solitary Waves COMSOL Multiphysics Wave Breaking

Scour around submarine pipes due to high-amplitude transient waves

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Water Science and Engineering 2020年第2期13卷 154-161页

作者： Hassan Vosoughi hooman Hajikandi Department of Civil Engineering Central Tehran BranchIslamic Azad UniversityTehran ***Iran

Estimation of scour dimensions below submarine pipelines is a vital step in designing offshore *** events like tsunami waves produce strong erosive forces below the underwater pipes,apt to create scour holes,jeopardizing the safety of the *** the importance of this issue,previous studies have mainly focused on steady flow cases,and the scour pattern below submarine pipes induced by high-amplitude transient waves has rarely been *** paper reports the results of 40 experimental runs on transient wave-induced scour below a model pipe in a laboratory flume under a variety of initial *** variables included the bed particle size and gradation,initial water depth,wave height,and slope of the bed *** were generated by a sudden release of water from a sluice gate,installed in the middle of the flume.A pressure transducer data acquisition system was used to record the wave heights at different time *** results indicate that,with a shallower initial depth of flow,the scour depth is relatively *** was also found that there exists a direct correlation between the induced wave height and the size of the scour *** was observed that,in clear water conditions,the size of the scour hole in coarse sediments is smaller,while in live-bed conditions,larger scour holes are created in coarser *** was also observed that at high wave amplitudes,the live-bed conditions are dominant,and consequently the bed elevation is altered.

关键词： Submarine pipe Scour hole Transient wave Flume experiment Live-bed condition Sediment

Shoaling Internal Solitary Waves and the Formation of Boluses

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The influence of environmental variables on distribution patterns of Irano-Turanian forests in Alborz Mountains, Iran

Open Journal of Fluid Dynamics（流体动力学） 2024年第2期 65页

作者： hooman Enayati Brian T.Helenbrook

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Journal of Mountain Science 2016年第8期13卷 1375-1386页

作者： hooman RAVANBAkHSH Alireza MOSHkI Faculty of Desert Studies Semnan University

Topographic and edaphic variables are the main ecological factor determining species spatial variability on mountainous forests. A field study was performed in central Alborz to investigate how the edaphic and topographic parameters can affect the tree and shrub communities. Initially, 27 forest stands were identified and the homogeneous units were separated regarding physiognomy. In each single homogeneous unit, one random sample plot （1000 m^2） and totally 43 plots were established. In each plot, the presence and abundance of all trees and shrubs were recorded and four soil samples were taken from depths of 0-5 and 5-20 cm. Concerning classification results, eight different forest communities were identified. The lowest and highest soil pH values were observed in Malus orientalis and pistacia-Amygdalus communities, respectively. The water saturation percent of pure- and mixed Juniperus excelsa and Rhus coriaria was the highest amongst communities. The clay content was the highest in pure ***. The 0-5 organic matter and Nitrogen content in mixed J. excelsa were significantly higher than pure J. excelsa and other communities. The CCA （Canonical Correspondence Analysis） altitude, precipitation, pH, results indicated that the EC, SP, clay and CaCO3 are the most important factors determine the distribution of trees and shrub in central Alborz.

关键词： Irano-Turanian Mountainouswoodlands Multivariate analysis Species-environment relationship

世界针灸学会联合会《针灸临床实践指南：胃食管返流病》推荐意见概述(英文)

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World Journal of Acupuncture-Moxibustion 2024年

作者：张雪萍周娟潘炜炳黄雪陈若菡刘镇文兰芯陈琛琛杨星月范乾白兴华 Amir hooman kazemi 北京中医药大学针灸推拿学院北京市东城区安定门社区卫生服务中心北京中医药大学东直门医院中国人民解放军总医院京北医疗区北京市丰台区中医医院常熟市中医院德黑兰大学

《针灸临床实践指南：胃食管反流病》（WFAS 007.9-2023)是世界针灸学会联合会2023年10月9日正式发布的针灸临床实践指南，也是首个针灸治疗胃食管反流病的指南。本指南内容主要包含指南目的、范围、适用人群、适用环境；针灸治疗胃食... 详细信息

《针灸临床实践指南：胃食管反流病》（WFAS 007.9-2023)是世界针灸学会联合会2023年10月9日正式发布的针灸临床实践指南，也是首个针灸治疗胃食管反流病的指南。本指南内容主要包含指南目的、范围、适用人群、适用环境；针灸治疗胃食管反流病概况；指南制定过程和推荐意见。本文重点介绍指南的推荐意见。本指南的颁布和实施将有利于规范针灸治疗胃食管反流病，对针灸在该病治疗中的推广应用将起到积极作用。

关键词：临床实践指南胃食管反流病食管及胃肠动力抑酸治疗针灸