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31.
Abolfazl Mohammadi Mehrdad Manteghian Amir H. Mohammadi Alireza Jahangiri 《Chemical Engineering Communications》2017,204(12):1420-1427
In this communication, the kinetic parameters of methane hydrate formation (induction time, quantity and rate of gas uptake, storage capacity (SC), and apparent rate constant) in the presence of sodium dodecyl sulfate (SDS), synthetized silver nanoparticles (SNPs), and mixture of SDS?+?SNPs have been studied. Experimental measurements were performed at temperature of 273.65?K and initial pressure of 7?MPa in a 460?cm3 stirred batch reactor. Our results show that adding SDS, SNPs and their mixture increases the quantity of gas uptake, water to hydrate conversion, and SC of methane hydrate formation, noticeably. Using 300?ppm SDS increases the SC and the quantity of methane uptake 615, and 770%, respectively, compared with pure water. Investigating the hydrate growth rate at the start of hydrate formation process shows that, using SNPs, SDS, and their mixture increases the initial apparent rate constant of hydrate rate, considerably. Our results show that the system of methane?+?water?+?SDS 500?ppm?+?SNPs 45?µM represents the maximum value of initial apparent rate constant, compared with other tested systems. 相似文献
32.
Solving non-convex economic dispatch problem with valve point effects using modified group search optimizer method 总被引:1,自引:0,他引:1
This paper presents a novel solution based on the group search optimizer (GSO) methodology in order to determine the feasible optimal solution of the economic dispatch (ED) problem considering valve loading effects. The basic disadvantage of the original GSO algorithm is the fact that it gives a near-optimal solution rather than an optimal one in a limited runtime period. In this paper, a new modified group search optimizer (MGSO) is presented for improving the scrounger and ranger operators of GSO. The proposed MGSO is applied on different test systems and compared with most of the recent methodologies. The results show the effectiveness of the proposed method and prove that MGSO can be applicable for solving the power system economic load dispatch problem, especially in large scale power systems. 相似文献
33.
34.
Soroosh?MahmoodiEmail authorView authors OrcID profile Hu?Guoqing Mehrdad?Nouri?Khajavi 《Journal of Coatings Technology and Research》2016,13(6):1123-1137
This study focuses on an innovative method for spin coating called the two-dimensional (2D) spin coating method. Using a centrifugal force applied by a rotary machine perpendicular to the wafer surface body, a vertical centrifuge force (VCF) was generated. The VCF allowed controllable artificial gravity acceleration to be generated and caused the coating to face this elevated gravity acceleration to adjust and normalize the high and low surface tension stresses. Previous surface leveling mathematics were analyzed and modified. The modified calculations indicate that the effect of additional gravity exerted on the liquid’s surface can reduce the amplitude of surface leveling. To experimentally investigate this phenomenon, a 2D spin coater was designed and manufactured. Higher artificial gravity overcame some common coating defects, such as cloudiness, edge beading, inner layer bubbling, and unsmooth surface leveling. Photoresist (AZP4620) was used as the coating material. The surface roughness was analyzed by atomic force microscopy (AFM) and the layer properties were also imaged by scanning electron microscopy (SEM). The AFM results (average and root-mean-square roughness) indicated a decrease in surface leveling amplitude by increasing the VCF. SEM images showed condensed layers without any porosity or rupture. The experimental results agreed with the simulations and calculated values. 相似文献
35.
Velayati Mahin Sabouri Zahra Masoudi Abdolhossein Mostafapour Asma Khatami Mehrdad Darroudi Majid 《SILICON》2022,14(13):7541-7554
Silicon - In this research, epoxy polyurethane-nano silica nanocomposites have been synthesized using an in-situ method, for which SiO2 nanocomposites had been initially ready in N,... 相似文献
36.
Liqiang Lu Jia Yu Xi Gao Yupeng Xu Mehrdad Shahnam William A. Rogers 《American Institute of Chemical Engineers》2020,66(6):e16969
This article investigated the fluidization of sands and small Geldart A biomass mixtures. The mixture fluidized like Geldart A type particles with a uniform bed expansion regime before bubbling. The video recorded color distance between pure sands and sands–biomass mixtures was used to estimate the sands–biomass mixing. The coarse-grained computational fluid dynamics–discrete element method with a hybrid drag model which couples the Syamlal–O'Brien drag and a filtered drag can capture the mixing while the simulation with Gidaspow drag predicted a segregated bed. The simulations were further validated with experimental measured pressure drops. The time averaged pressure drop equals the weight of the bed material, however, its fluctuation is about three times of the bed material fluctuation. 相似文献
37.
Mehrdad Azamian Jazi Ahmad Ramezani S.A. Seyyed Arash Haddadi Saeed Ghaderi Fariba Azamian 《应用聚合物科学杂志》2020,137(15):48570
Polyvinyl acetate (PVAc) nanocomposites for wood adhesives containing different amounts of colloidal silica nanoparticles (CSNs) were synthesized via in situ one-step emulsion polymerization. The adhesion strength of wood specimens bonded by PVAc nanocomposites was investigated by the tensile test. Thermal properties of PVAc nanocomposites were also characterized by differential scanning calorimetry and thermogravimetric analysis. Rheological and morphological properties of the PVAc nanocomposites were investigated using rheometric mechanical spectrometry and field emission scanning electron microscopy (FESEM), respectively. The obtaining results showed that the shear strength of PVAc nanocomposite including 1 wt. % CSNs has the highest shear and tensile strength about 4.7 and 3.2 MPa, respectively. A small increment of Tg (~3 °C) and considerable increment of the ash content proved the enhancement of PVAc thermal characterization in the presence of CSNs. FESEM results showed uniform dispersion of nanoparticles throughout the PVAc matrix due to using the in situ emulsion polymerization process. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48570. 相似文献
38.
Bum-Jin Chung Min Chan Kim Mehrdad Ahmadinejad 《Journal of Mechanical Science and Technology》2008,22(1):127-133
Film-wise and drop-wise condensation experiments were carried out at atmospheric pressure varying the condensing plates, their
inclinations and orientations (upward or downward facing), and the air concentrations. As expected, dropwise condensation
showed much higher heat transfer rates than corresponding film-wise condensation in the pure steam cases. However, with the
presence of air, both modes of condensation showed similar heat transfer rates due to the high thermal resistance of the air-rich
layer. Both modes of condensation showed systematic decreases in heat transfer as the angle of the plate to the horizontal
decreased and as the concentration of air increased. A noteworthy observation made during the tests on the plate orientation
showed that condensation heat transfer rates on the upward facing plate were slightly higher than those beneath the downward
facing plate in the pure steam cases but that the trends were reversed in the steam and air mixture cases. 相似文献
39.
Thermal,mechanical, and barrier properties of polyethylene/surlyn/organoclay nanocomposites blown films prepared by different mixing methods 下载免费PDF全文
Homayoon Hosseinkhanli Jamal Aalaie Mahdi Abdollahi Talat Khalkhali Mehrdad Shojaei 《乙烯基与添加剂工艺杂志》2015,21(1):60-69
(Low‐density polyethylene) (LDPE)/clay nanocomposites were prepared by melt blending in a twin‐screw extruder by using different mixing methods. Zinc‐neutralized carboxylate ionomer was used as a compatibilizer. Blown films of the nanocomposites were then prepared. The effect of mixing method on the clay dispersion and properties of the nanocomposites was evaluated by wide‐angle X‐ray diffraction analysis, mechanical properties, thermal properties, and barrier properties. The structure and properties of nanocomposites containing different amounts of nanoclay prepared by selected mixing techniques were also investigated. It was found that melt compounding of Surlyn/clay masterbatch with pure LDPE and Surlyn (two‐step‐a method) results in better dispersion and intercalation of the nanofillers than melt mixing of LDPE/Surlyn/clay masterbatch with pure LDPE and surlyn (two‐step‐b method) and direct mixing of LDPE with clay. The films containing ionomer have good barrier properties. A wide‐angle X‐ray diffraction pattern indicates that intercalation of polymer chains into the clay galleries decreases by increasing the clay content. Barrier properties and tensile modulus of the films were improved by increasing the clay content. In addition, tensile strength increased in the machine direction, but it decreased in the transverse direction by increasing the clay content. DSC results showed that increasing the clay content does not show significant change in the melting and crystallization temperatures. The results of thermogravimetric analysis showed that the thermal stability of the nanocomposites decreased by increasing the clay content more than 1 wt%. J. VINYL ADDIT. TECHNOL., 21:60–69, 2015. © 2014 Society of Plastics Engineers 相似文献
40.
Mehrdad Soltani
Ross B. Corotis
《Structural Safety》1988,5(4):239-252A systematic design approach based on applying weights to modes of failure is proposed. Representative individual failure modes are identified on the limit state surface using a nonlinear structural analysis program. Modal failure probabilities are computed in load space (in which randomness in structural resistance is included), and linearized around mean plastic moment capacities. Single- and multi-objective formulations with objectives of failure cost and initial cost, and with mean plastic moment capacities of structural members as decision variables are used. An iterative procedure with successively tighter bounds on the decision variables is employed. The procedure is applied to a simple frame for which optimum plastic moment capacities (single-objective case) and a trade-off curve between future (failure) cost and initial cost (multi-objective case) are found. 相似文献