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Towards skin polarization characterization using polarimetric technique

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2009年第8期10卷 602-608页

作者： Pejhman ghassemi mohammad Hossein MIRANBAYGI Biomedical Engineering Group Department of Electrical and Computer EngineeringTarbiat Modares University

Measurement of optical properties of skin is an expanding and growing field of *** studies have shown that the biological tissue,especially skin,changes the polarization state of the incident *** this property will enable the study of abnormalities and diseases that alter not only the light intensity but also its polarization *** this paper we report an experimental study for measuring changes of polarization state of the light scattered from a phantom similar to a sample model of scattering *** the notation of Stokes vector for the polarized light and Mueller matrix for the sample with its polarization properties,we have shown that some elements of the matrix were particularly sensitive to the changes of the polarization-altering physical properties of the scatterers within the phantom.

关键词： Polarization Skin Phantom Scattering polarimetry Mueller matrix Stokes vector

Microscopic and macroscopic atomization characteristics of a pressure-swirl atomizer, injecting a viscous fuel oil

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Chinese Journal of Chemical Engineering 2020年第1期28卷 9-22页

作者： Seyed mohammad Ali Najafi Pouria Mikaniki Hojat ghassemi School of Mechanical Engineering Iran University of Science and Technology(IUST)P.O.B.16765-163TehranIran

Combustion of heavy fuels is one of the main sources of greenhouse gases, particulate emissions, ashes, NOxand SOx. Gasification is an advanced and environmentally friendly process that generates combustible and clean gas products such as hydrogen. Some entrained flow gasifiers operate with Heavy Fuel Oil(HFO) feedstock. In this application, HFO atomization is very important in determining the performance and efficiency of the *** atomization characteristics of HFO(Mazut) discharging from a pressure-swirl atomizer(PSA) are studied for different pressures difference(Δp) and temperatures in the atmospheric ambient. The investigated parameters include atomizer mass flow rate( _m), discharge coefficient(CD), spray cone angle(θ), breakup length(Lb), the unstable wavelength of undulations on the liquid sheet(λs), global and local SMD(sauter mean diameter) and size distribution of droplets. The characteristics of Mazut sheet breakup are deduced from the shadowgraph technique. The experiments on Mazut film breakup were compared with the predictions obtained from the liquid film breakup model. Validity of the theory for predicting maximum unstable wavelength was investigated for HFO(as a highly viscous liquid). A modification on the formulation of maximum unstable wavelength was presented for HFO. SMD decreases by getting far from the atomizer. The measurement for SMD and θ were compared with the available correlations. The comparisons of the available correlations with the measurements of SMD andθ show a good agreement for Ballester and Varde correlations, respectively. The results show that the experimental sizing data could be presented by Rosin-Rammler distributions very well at different pressure difference and temperatures.

关键词： Gasifier Heavy fuel oil Atomization Pressure-swirl atomizer Mazut Size distribution Wavelength Viscosity

Experimental study of a heavy fuel oil atomization by pressure-swirl injector in the application of entrained flow gasifier

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Chinese Journal of Chemical Engineering 2019年第4期27卷 765-771页

作者： Pouria Mikaniki Seyed mohammad Ali Najafi Hojat ghassemi School of Mechanical Engineering Iran University of Science and Technology

The available SMD(Sauter mean diameter) correlations on pressure-swirl injectors predict droplet sizing very different from each other, especially for heavy fuels. Also there was a lack in the literature for comparing available correlations. So an experimental study was conducted on a heavy fuel oil(HFO) spray, Mazut 380. A pressure swirl injector was designed and fabricated. The experiments for Mazut at 40℃ and 80℃ were compared with the results for water, including spray half cone angle, breakup length and mean droplet diameter,at different injection pressures. Lower spray angle, higher breakup length and larger droplets were observed for lower injection pressures and higher liquid viscosity. SMD was about 75 μm for water and about 87 μm for Mazut at 80℃. The results for droplet mean diameter were also compared with correlations from previous studies on pressure swirl atomizers. The SMD results show that for water spray, LISA method was in good agreement,also Babu and Ballester correlations were successful when high viscosity fluid was injected.

关键词： Atomization Pressure-swirl injector Mazut Size distribution Fuel Viscosity

Effect of synthetic fibers on resisting scour caused by horizontal jet

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Water Science and Engineering 2022年第2期15卷 152-160页

作者： Amin ghassemi Mohsen Nasrabadi mohammad Hossein Omid Ali Raeesi Estabragh Department of Civil Engineering Queen's UniversityKingston K7L 3N6Canada Department of Water Science and Engineering Arak UniversityArak 38481-77584Iran Department of Irrigation and Reclamation Engineering University of TehranKaraj 31587-77871Iran

Given that the development of scour downstream of hydraulic structures increases the risk of structural damage,it is important to find cost-effective and environmental approaches to reduce this *** study aimed to experimentally evaluate the effect of synthetic fibers on the scour profile downstream of a sluice gate with a rigid *** were performed with the same Froude number and with different weight percentages of synthetic fibers on both non-cohesive and cohesive *** uniform sand was used as the non-cohesive sediment,and three different cohesive sediments were prepared by mixing different percentages of kaolinite soil with the used *** scouring experiments showed that the presence of synthetic fibers did not considerably affect the scour hole dimension in non-cohesive *** of the scour in the cohesive sediments in silty sand(SM)texture found that an increase in the percentage of silt reduced the scour hole *** effect of synthetic fibers on scour of SM-texture-based sediments was also investigated,and the results showed that increasing the percentage of synthetic fibers decreased the scour hole *** addition,the cohesive sediments in SM texture did not have a similar non-dimensional scour profile,and the presence of synthetic fibers did not significantly affect the scour hole.

关键词： Local scouring Synthetic fibers Horizontal jet SM soil texture Scour profile

Numerical Analysis of Electromagnetic Control of the Boundary Layer Flow on a Ship Hull

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Open Journal of Fluid Dynamics 2014年第1期4卷 74-82页

作者： mohammad Bakhtiari Hassan ghassemi Department of Ocean Engineering Amirkabir University of Technology Tehran Iran

In this article, electromagnetic control of turbulent boundary layer on a ship hull is numerically investigated. This study is conducted on the geometry of tanker model hull. For this purpose, a combination of electric and magnetic fields is applied to a region of boundary layer on stern so that produce wall parallel Lorentz forces in streamwise direction as body forces in stern flow. The governing equations including RANS equations with SST k-ω?turbulent model coupled with electric potential equation are numerically solved by using Ansys Fluent codes. Accuracy of this turbulent model of Fluent in predicting Turbulent flow around a ship is also tested by comparing with available experimental results that it shows a good agreement with experimental data. The results obtained for ship flow show that by applying streamwise Lorentz forces that are large enough, flow is accelerated. The results are caused to delay or avoid the flow separation in stern, increase the propeller inlet velocity, create uniform flow distribution behind the ship’s hull in order to improve the propeller performance, and finally decrease the pressure resistance and total resistance.

关键词： Electromagnetic Control Boundary Layer Turbulent Flow Flow Separation Resistance

Finite Element Numerical Method for Nonlinear Interaction Response Analysis of Offshore Jacket Affected by Environment Marine Forces

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Open Journal of Marine Science 2015年第4期5卷 422-442页

作者： Seyyed Mahmood ghassemi Zadeh Reza Shojayee Baghdar Seyyed mohammad Saleh Vaziri Kang Olia Marine Structures Engineering Amirkabir University of Technology Tehran Iran Hydraulic Structures Engineering Shahrood University Shahrood Iran Structure Engineering Ferdowsi University Mashhad Iran

In this paper a nonlinear response of a fixed offshore platform under the combined forces of waves, wind and sea currents is presented. Wave force acting on the elements is calculated using Morison equation. Hydrodynamic loads on horizontal and vertical tubular members and the dynamic response of offshore fixed platform coupled with distribution of displacement, axial force, and bending moment along the base of the platform for regular and severe cases have been investigated. The structure must be able maintain production in a one-year wave return period condition and also to be able to continue with one hundred-year storm return period. The results of this study show that bending moment values with a one-year wave return period condition for the base platform and junction of platform to deck are 70 percent and 59 percent, respectively more than bending moment with a one-year wave return period. The direction of wave and wind hit has significant effects on the shift platform response, also nonlinear response is important for the safe design and operation of offshore structures.

关键词： Fixed Jacket Platform Finite Element Method Stokes Wave Theory Nonlinear Response of Structure