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Multiscale RBF-based central high resolution schemes for simulation of generalized thermoelasticity problems

Frontiers of Structural and Civil Engineering 2019年第2期13卷 429-455页

作者： Hassan YOUSEFI alireza taghavi kani Iradj MAHMOUDZADEH kani School of Civil Engineering College of EngineeringUniversity of TehranTehran11155-4563Iran Department of Civil Engineering Arak University of TechnologyArak***Iran

In this study, average-interpolating radial basis functions (RBFs) are successfully integrated with central high-resolution schemes to achieve a higher-order central method. This proposed method is used for simulation of generalized coupled thermoelasticity problems including shock (singular) waves in their solutions. The thermoelasticity problems include the LS (systems with one relaxation parameter) and GN (systems without energy dissipation) theories with constant and variable coefficients. In the central high resolution formulation, RBFs lead to a reconstruction with the optimum recovery with minimized roughness on each cell: this is essential for oscillation-free reconstructions. To guarantee monotonic reconstructions at cell-edges, the nonlinear scaling limiters are used. Such reconstructions, finally, lead to the total variation bounded (TVB) feature. As RBFs work satisfactory on non-unifdrm cells/grids, the proposed central scheme can handle adapted cells/grids. To have cost effective and accurate simulations, the multiresolution-based grid adaptation approach is then integrated with the RBF-based central scheme. Effects of condition numbers of RBFs, computational complexity and cost of the proposed scheme are studied. Finally, different 1-D coupled thermoelasticity benchmarks are presented. There, perfonnance of the adaptive RBF-based formulation is compared with that of the adaptive Kurganov-Tadmor (KT) second-order central high-resolution scheme with the total variation diminishing (TVD) property.

关键词： central high resolution schemes RBFs higher order accuracy generalized thermoelasticity multiresolutionbased adaptation

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Response of a spherical cavity in a fully-coupled thermo-poro-elastodynamic medium by cell-adaptive second-order central high resolution schemes

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Underground Space 2018年第3期3卷 206-217页

作者： Hassan Yousefi alireza taghavi kani Iradj Mahmoudzadeh kani School of Civil Engineering University of TehranTehranIran Department of Civil Engineering Arak University of TechnologyIran

In this study,fully coupled thermo-poroelastic saturated media are simulated by a grid/cell adaptive central high resolution scheme.The central method corresponds to the second order Kurganov-Tadmor(KT)scheme working on adapted cells with the total variation diminishing(TVD)stability condition.The coupled equations include motion,fluid flow,heat flow,continuity condition,and a constitutive equation.The grid/cell adaptation is performed by the interpolating wavelet transform in the multiresolution framework to capture fine scale responses and to obtain a computationally effective solver.With respect to the use of central schemes,the coupled equations should be re-expressed as a system of coupled first-order hyperbolic-parabolic partial differential equations(PDEs)with possible source(load)terms.The system is initially derived in the Cartesian coordinate system,and it is subsequently modified to consider a spherical cavity in isotropic,symmetric,and saturated media in the spherical coordinate system.It is assumed that the cavity boundary is subjected to sudden time-dependent thermal/mechanical sources.Discontinuous propagating fronts develop in the media due to the aforementioned loading.It is challenging to handle these solutions with numerical methods,and special attention is required to prevent/control numerical dispersion and dissipation.Hence,as previously mentioned,adaptive central high resolution schemes are employed in the present study.

关键词： Coupled waves Saturated porous media Thermo-poroelastic Spherical cavity Central high resolution schemes Adaptive simulations

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Wavelet-based iterative data enhancement for implementation in purification of modal frequency for extremely noisy ambient vibration tests in Shiraz-Iran

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Frontiers of Structural and Civil Engineering 2020年第2期14卷 446-472页

作者： Hassan YOUSEFI alireza taghavi kani Iradj MAHMOUDZADEH kani Soheil MOHAMMADIA High Performance Computing Lab Schoo of Civil EngineeringFaculy of EngineeringUniversity of TehranTehranIran School of Civil Engineering Faculty of EngineeringUniversity of TehranTehranIran

The main purpose of the present study is to enhance high-level noisy data by a wavelet-based iterative filtering algorithm for identification of natural frequencies during ambient wind vibrational tests on a petrochemical process tower.Most of denoising methods fail to filter such noise properly.Both the signal-to-noise ratio and the peak signal-to-noise ratio are small.Multiresolution-based one-step and variational-based filtering methods fail to denoise properly with thresholds obtained by theoretical or empirical method.Duc to the fact that it is impossible to completely denoise such high-level noisy data,the enhancing approach is used to improve the data quality,which is the main novelty from the application point of view here.For this iterative method,a simple computational approach is proposed to estimate the dynamic threshold values.Hence,different thresholds can be obtained for different recorded signals in one ambient test.This is in contrast to commonly used approaches recommending one global threshold estimated mainly by an empirical method.After the enhancements,modal frequencies are directly detected by the cross wavelet transform(XWT),the spectral power density and autocorrelation of wavelet coefficients.Estimated frequencies are then compared with those of an undamaged-model,simulated by the finite element method.

关键词： ambient vibration test high level noise iterative signal enhancement wavelet cross and autocorrelation of wavelets

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Powering the future: A comprehensive review on calcium-ion batteries

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Journal of Energy Chemistry 2024年第3期90卷 77-97,I0004页

作者： Ameneh taghavi-Kahagh Hossein Roghani-Mamaqani Mehdi Salami-Kalajahi Faculty of Polymer Engineering Sahand University of TechnologyP.0.Box 51335-1996Tabriz Iran Institute of Polymeric Materials Sahand University of TechnologyP.0.Box 51335-1996Tabriz Iran

Due to concerns regarding the future availability,cost,and safety of lithium in Li-ion batteries(LIBs),researchers are exploring alternative chemistries such as Na-ion,Li-S,Li-air,and multivalent ion technologies.Multivalent ion technologies,which utilize divalent or trivalent ions,like Mg^(2+),Ca^(2+),and Al^(3+),show promise in achieving greater energy densities than LIBs due to their ability to deposit uniformly on anodes and intercalate into cathodes.While magnesium-ion batteries(MIBs) have been the primary area of research for multivalent ion batteries,the cost-effectiveness and abundance of calcium have sparked a growing interest in calcium-ion batteries(CIBs) in recent years.Compared to LIBs,CIBs have the potential to provide longer cycle life,enhanced safety,and increased energy densities.However,the development of CIBs comes with several challenges,such as finding suitable electrode and electrolyte materials that ensure the stability and safety of the battery.The primary hurdle in CIBs lies in the plating/stripping process.There is a significant hindrance preventing the occurrence of plating/stripping in CIBs,which lies in the formation of a passive layer resulting from the decomposition of the electrolyte.The objective of this article is to examine the advancements made in CIBs.Additionally,it aims to comprehensively assess the mechanisms and materials employed in various battery components,as well as the obstacles encountered in CIBs.This includes recent advancements in electrode materials,electrolytes,cell configurations,and the challenges and opportunities for enhancing the performance and commercial viability of CIBs.

关键词： Ca-ion batteries Cathode Anode Electrolyte

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Successful interferon desensitization in a patient with chronic hepatitis C infection

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World Journal of Gastroenterology 2009年第33期15卷 4196-4198页

作者： Seyed alireza taghavi Ahad Eshraghian Gastroentero-hepatology Research Center of Shiraz University of Medical Science Nemazee Hospital

Treatment of hepatitis C, even when absolutely necessary, is almost impossible when interferon cannot be administered for any reason. We report a 65-year-old patient with chronic hepatitis C virus (HCV) infection and fibrosis, who was unable to receive interferon because of systemic hypersensitivity. The patient was desensitized successfully through gradual incremental exposure to interferon, and HCV infection was eradicated after a complete course of treatment, with no further allergic reactions. This case report that describes successful eradication of hepatitis C in a patient with advanced liver disease after desensitization to interferon revealed that desensitization may not necessarily damage the therapeutic efficacy of the drug.

关键词：丙型肝炎病毒干扰素脱敏患者慢性病毒感染过敏反应药物疗效

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Adsorption of neodymium,terbium and dysprosium using a synthetic polymer-based magnetic adsorbent

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Journal of Rare Earths 2023年第11期41卷 1796-1804,I0006页

作者： Hamedreza Javadian Mehdi taghavi Montserrat Ruiz Inderjeet Tyagi Majid Farsadrooh Ana Maria Sastre Department of Chemical Engineering ETSEIBUniversitat Politècnica de CatalunyaDiagonal 64708028BarcelonaSpain Department of Chemistry Faculty of ScienceShahid Chamran University of Ahvaz61357-43337Iran Department of Chemical Engineering EPSEVGUniversitat Politècnica de CatalunyaAv.Víctor Balaguers/n08800Vilanova i la GeltrúSpain Centre for DNA Taxonomy Molecular Systematics DivisionZoological Survey of IndiaKolkata700053India Renewable Energies Research Laboratory Department of ChemistryFaculty of ScienceUniversity of Sistan and BaluchestanP.O.Box 98135674ZahedanIran

In this study,a polyamide with methine-thiophene and pyrimidine linkages(poly(pyrimidine-thiophene-amide)(PPTA))was synthesized.Then,magnetic PPTA(M-PPTA)was synthesized using the hydrothermal technique.The products were analyzed by Fourier-transform infrared spectroscopy(FTIR),nuclear magnetic resonance(NMR),X-ray diffraction(XRD),thermogravimetric analysis(TGA),field-emission scanning electron microscopy(FE-SEM),and a vibrating-sample magnetometer(VSM).The nanocomposite exhibits a saturation magnetization of 50.44 emu/g recorded by VSM analysis.The ability of M-PPTA to bind dysprosium(Dy^(3+)),terbium(Tb^(3+)),and neodymium(Nd^(3+))was investigated.Using 0.15 g of M-PPTA to test the adsorption of the rare earth elements(50 mg/L)at pH=5.5,the percentage of adsorption for Dy^(3+),Tb^(3+),and Nd^(3+)is 98.41%,97.48%and 95.67%,respectively.Pseudo-second-order(PSO)significantly fits the adsorption kinetic data.Freundlich equation was used to describe the adsorption equilibrium data of Dy^(3+)and Tb^(3+),while Langmuir model was used to simulate Nd^(3+)adsorption data.Increasing the temperature leads to an increase in the performance of M-PPTA,and an endothermic adsorption process was confirmed by the positive values ofΔH.After four adsorption-desorption cycles,the efficiency of adsorption of Dy^(3+),Tb^(3+),and Nd^(3+)by M-PPTA is88.75%,86.37%,and 84.64%,respectively.An antagonism effect is observed for the adsorption of the individual ions in a ternary solution.

关键词： Polyamide Lanthanides Magnetic nanocomposite Adsorption Rare earth elements

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Evaluation of Serum Vitamin D Concentration and Blood Eosinophil and Basophil Counts in Patients With Vitiligo:A Cross-sectional Study From Rafsanjan and Zarand,Iran

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International Journal of Dermatology and Venereology 2023年第3期6卷 136-140页

作者： Razieh Taghizadeh Ghavamabadi Reihaneh Pishgooie Shadi Behfar Mohammad Mohsen taghavi Abdolreza Babaee Zahra Taghipour Department of Anatomy School of MedicineRafsanjan University of Medical SciencesRafsanjanKerman ***Iran Physiology-Pharmacology Research Center Rafsanjan University of Medical SciencesRafsanjanKerman ***Iran Department of Internal Medicine Rafsanjan University of Medical SciencesRafsanjanKerman ***Iran Department of Dermatology Rafsanjan University of Medical SciencesRafsanjanKerman ***Iran

Objective:Vitiligo is a chronic autoimmune depigmenting skin disorder.In this disease,the destruction of functional melanocytes can lead to reduced or absent pigmentation of the skin.Vitamin D deficiency has been reported in some autoimmune diseases.The association of eosinophils and basophils with autoimmune diseases has also been recently examined.The present study was performed to evaluate the serum vitamin D concentration and blood eosinophil and basophil counts in patients with vitiligo.Methods:Data from 30 patients aged 20 to 40 years with vitiligo and 30 healthy people were collected.Blood samples were obtained to evaluate the serum vitamin D concentration,and eosinophil and basophil counts.The serum vitamin D concentration was measured by enzyme-linked immunosorbent assay.Independent t-test was used to compare the quantitative variables between the groups.Results:This descriptive cross-sectional study involved 30 patients with vitiligo.The average serum vitamin D concentration was significantly lower in the case group than in the control group(P=0.01).Furthermore,the mean serum vitamin D concentration was significantly lower in women than in men(P=0.03).The average eosinophil and basophil counts were not significantly different between the case and control groups.Discussion:The results of this study showed that the serum vitamin D concentration is low in patients with vitiligo.However,whether this reduction is a factor in the promotion of vitiligo or occurs after the onset of vitiligo remains unknown.Further studies on the serum vitamin D concentration in patients with vitiligo are needed to clarity this issue and develop effective treatments.

关键词： autoimmunity pigmentation disorders vitiligo 1,25-dihydroxyvitamin D3

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Performance enhancement of bimetallic Co-Ru/CNTs nano catalysts using microemulsion technique

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Journal of Energy Chemistry 2013年第5期22卷 747-754页

作者： Ahmad Tavasoli Somayeh taghavi School of Chemistry College of Science University of Tehran

Bimetallic cobalt-ruthenium nano catalysts supported on carbon nanotubes(CNTs)are prepared using microemultion technique with water-to-surfactant ratios of 0.5—1.5.The nano catalysts were extensively characterized by different methods and their activity and selectivity in Fischer-Tropsch synthesis(FTS)have been assessed in a fixed-bed microreactor.The physicochemical properties and performance of the nanocatalysts were compared with the catalyst prepared by impregnation method.Very narrow particle size distribution has been produced by the microemulsion technique at relatively high loadings of active metals(15 wt%Co and 1 wt%Ru).According to TEM images,small Co particles(2—7 nm)were mostly confined inside the CNTs.Comparing with the catalyst prepared by impregnation,the use of microemulsion technique with water to surfactant ratio of 0.5 decreased the average cobalt oxide particle size to 4.8 nm,the dispersion was almost doubled and the reduction increased by 28%.Activity and selectivity were found to be dependent on the catalyst preparation method and water-to-surfactant ratio(as well as cobalt particle sizes).CO conversion increased from 59.1%to 75.1%and the FTS rate increased from 0.291 to0.372 gHC/(gcath).C5+liquid hydrocarbons selectivity decreased from 92.4%to 87.6%.

关键词： Fischer-Tropsch synthesis cobalt ruthenium microemulsion particle size

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纳米微气泡存在下浮选机和浮选柱回收细粒磷酸盐矿物的比较

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Journal of Central South University 2022年第1期29卷 102-115页

作者： Fatemeh taghavi Mohammad Noaparast Ziaeddin Pourkarimi Fardis Nakhaei School of Mining Engineering College of EngineeringUniversity of TehranTehranIran Department of Mineral Processing and Applied Research Iran Mineral Processing Research Center(IMPRC)KarajIran School of Chemical and Minerals Engineering NorthWest UniversityPotchefstroomSouth Africa

细粒浮选一直是许多矿物加工厂面临的主要问题之一。由于细颗粒的气泡粒子碰撞概率很低,因此降低了浮选效率。细粒的存在通常不利于浮选过程,影响了浮选精矿的选择性和质量,而且增加了试剂的消耗量。因此,在大多数加工厂中,会将部分颗... 详细信息

细粒浮选一直是许多矿物加工厂面临的主要问题之一。由于细颗粒的气泡粒子碰撞概率很低,因此降低了浮选效率。细粒的存在通常不利于浮选过程,影响了浮选精矿的选择性和质量,而且增加了试剂的消耗量。因此,在大多数加工厂中,会将部分颗粒输送到尾矿池中,以减少这些问题的影响,并提高浮选过程的选择性。由于d80小于30μm的颗粒的存在,使伊朗的Esfordi磷酸盐厂损失了至少30%的处理能力。将这些P_(2)O_(5)含量为15.9%的细颗粒转移到尾矿坝,从经济和环境两方面来看,细颗粒的加工对磷酸盐工业具有重要意义。本文探讨了通过浮选工艺处理磷酸矿选矿厂的细尾矿的问题,尽管传统观点认为超细颗粒不可浮选。根据冶金工艺性能结果,比较了有无纳米气泡(NBs)时,浮选机和浮选柱两种处理工艺下磷酸盐矿物的浮选行为。由于NBs(由水动力空化作用产生)具有有趣的和独特的性能,如高稳定性、耐久性和高比表面积,提高了其在采矿、冶金和环境领域的应用。本研究结果表明,在没有NBs的情况下,使用浮选机工艺获得了P_(2)O_(5)含量为26.9%、回收率为29.13%的精矿,而使用浮选柱工艺,得到的P_(2)O_(5)含量为31.6%,回收率为32.74%的精矿。在NBs存在的情况下,通过浮选机和浮选柱获得精矿的回收率分别为40.49%和41.26%,P_(2)O_(5)含量分别为28.47%和30.43%。对比研究表明,在NBs存在的情况下,与浮选机相比,浮选柱工艺对磷矿的处理效率更高,泡沫层更厚。

关键词：浮选柱浮选机磷酸盐尾矿黏液纳米气泡 Venturi管水动力空化

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Alleviation of spike stall in axial compressors utilizing grooved casing treatment

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Chinese Journal of Aeronautics 2015年第3期28卷 649-658页

作者： Reza taghavi-Zenouz Sarallah Abbasi School of Mechanical Engineering Iran University of Science and Technology School of Mechanical Engineering Arak University of Technology

Abstract This article deals with application of grooved type casing treatment for suppression of spike stall in an isolated axial compressor rotor blade row. The continuous grooved casing treatment covering the whole compressor circumference is of 1.8 mm in depth and located between 90% and 108% chord of the blade tip as measured from leading edge. The method of investigation is based on time-accurate three-dimensional full annulus numerical simulations for cases with and without casing treatment. Discretization of the Navier Stokes equations has been carried out based on an upwind second-order scheme and k-a-SST （Shear Stress Transport） turbulence modeling has been used for estimation of eddy viscosity. Time-dependent flow structure results for the smooth casing reveal that there are two criteria for spike stall inception known as leading edge spillage and trailing edge backftow, which occur at specific mass flow rates in near-stall conditions. In this case, two dominant stall cells of different sizes could be observed. The larger one is caused by the spike stall covering roughly two blade passages in the circumferential direction and about 25% span in the radial direction. Spike stall disturbances are accompanied by lower frequencies and higher amplitudes of the pressure signals. Casing treatment causes flow blockages to reduce due to allevi- ation of backflow regions, which in turn reduces the total pressure loss and increases the axial veloc- ity in the blade tip gap region, as well as tip leakage flow fluctuation at higher frequencies and lower amplitudes. Eventually, it can be concluded that the casing treatment of the stepped tip gap type could increase the stall margin of the compressor. This fact is basically due to retarding the movement of the interface region between incoming and tip leakage flows towards the rotor leading edge Diane and suttressing the reversed flow around the blade trailing edee.

关键词： Axial compressor Casing treatment Frequency spectrum Spike stall inception Tip leakage flow

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