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101.
102.
In this work, thermal buckling analysis of symmetric and anti-symmetric laminated composite plates with a cut-out is presented. The plate is assumed to be subjected to a uniform temperature rise for different boundary conditions. The thermal buckling analysis is performed using the code developed in MATLAB software. The stiffness matrices and thermal force vector are derived according to first-order shear deformation theory (FSDT). To have more control on the mesh pattern around the cut-out, convenient meshes are manually constructed using a mesh generation algorithm in which mesh density around the hole can be controlled. The results of FEM code is compared with ABAQUS's solutions and with those available in the literature. After that, the effects of cut-out size, boundary conditions, plate aspect ratio, and stacking sequence on critical thermal buckling temperature are investigated for symmetric and anti-symmetric plates. Also, plates with cut-out located at positions other than the center of plate are investigated and useful conclusions are derived from the numerical results. 相似文献
103.
Mohammad Zhiani Jalal Jalili Behzad Rezaei Mohammad Mohammadi Taghiabadi 《International Journal of Hydrogen Energy》2013
We reported the direct reduction of H2PtCl6 and RuCl3 solution containing acetylene black powder by Na2S2O4 to make Pt–Ru (20–10 wt%) supported on acetylene black (Pt–Ru/AB) as a nanocatalyst for methanol electrooxidation in acidic media. The electrochemical activity of catalyst was studied by electrochemical impedance spectroscopy, linear sweep voltammetry, cyclic voltammetry and chronoamperometry. Structural aspects of the Pt–Ru (20–10 wt%)/AB were studied by transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. The analysis of electrochemical results indicated lower charge transfer resistance, higher peak current for Pt–Ru (20–10 wt%)/AB compared to the commercial catalyst, Pt–Ru (20–10 wt%)/carbon Vulcan. XRD spectra verified a face centered cubic structure for the synthesized Pt–Ru/AB and its particle size was mostly 10 nm according to TEM and XRD images. In DMFC, Pt–Ru/AB had superior performance compared to the commercial catalyst in all current densities, which could be attributed to enhancement of the methanol oxidation kinetics, higher conductivity, and more uniform distribution of the ionomer in anode catalyst layer. 相似文献
104.
Hajar Abbasi Karamatollah Rezaei Ladan Rashidi 《Journal of the American Oil Chemists' Society》2008,85(1):83-89
In this study, essential oils from pomegranate seeds of the Malas variety from Shahreza, Iran, were extracted using hexane
and petroleum benzene applying four extraction methods: normal stirring, soxhlet, microwave irradiation, and ultrasonic irradiation.
Also, supercritical fluid extraction (SFE) using CO2 under different conditions was used for comparison. Different methods of extraction with organic solvents (normal stirring,
soxhlet, microwave irradiation, and ultrasonic irradiation) showed significant differences in the extraction yields. However,
no differences were found when a given method (e.g., microwave irradiation) was applied using different organic solvents.
On the other hand, different extraction conditions from the various runs of SFE resulted in different extraction yields, all
of which were lower than those of the other extraction methods using organic solvents. No significant differences were observed
in the fatty acid compositions of the extracted oils using organic solvents. However, the fatty acid compositions of the oils
extracted under different conditions of the SFE system indicated significant differences among several fatty acids including
unsaturated fatty acids. 相似文献
105.
Mohammad Reza Nabid Mahvash Abedi Seyed Jamal Tabatabaei Rezaei 《Polymer Bulletin》2012,68(5):1327-1339
Abstract
A new heterobifunctional initiator, 2,3-bis(2-bromo-2-methylpropionyloxy) succinic acid, was synthesized and used in preparation of A2B2 miktoarm star copolymers, (polystyrene)2(poly(ε-caprolactone))2, by combination of atom transfer radical polymerization (ATRP) and Controlled ring-opening polymerization (ROP). The structures of products were confirmed by the 1H NMR, 13C NMR, FT–IR, elemental analysis, differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). GPC traces show that the obtained polymers have a relatively narrow molecular weight distribution. The compositions of resulting miktoarm star copolymers were very close to theoretical. 相似文献106.
Mohammad-Taghi Golmakani Karamatollah Rezaei Sara Mazidi Seyyed Hadi Razavi 《Food science and biotechnology》2012,21(2):355-363
The influence of different organic carbon sources (glucose, ethanol, and acetic acid) at different concentrations (0.1, 0.5,
and 1.0 g/L for batch and 1.0, 2.0, and 3.0 g/L for fed-batch) were studied in the mixotrophic production (using both light
and carbon source) of γ-linolenic acid (GLnA) by spirulina (Arthrospira platensis). The obtained spirulina was analyzed in terms of biomass, lipid, and GLnA production. In the batch media, increasing the
concentrations of glucose, ethanol, and acetic acid led to an increase in the biomass, lipid, and GLnA production. However,
carbon sources at concentrations greater than 1.0 g/L in fed-batch media appeared to have no significant effects on the above
parameters. It was also demonstrated that biomass, lipid, and GLnA production using ethanol and acetic acid could be as good
as those achieved with the classic glucose-based culture media. 相似文献
107.
Mohammad Ali Najafi Karamatollah Rezaei Mohammad Safari Seyyed Hadi Razavi 《Food science and biotechnology》2012,21(1):51-57
In this study, effects of 8 different sourdough starters prepared with Saccharomyces cerevisiae, Lactobacillus plantarum, L. acidophilus, and Leuconostoc mesenteroides were investigated on the phytic acid level and mole ratio of phytic acid to zinc in a traditional Iranian bread (sangak). Different sourdough preparations were made and incubated at 30°C for 16 h and added to the dough at 10, 20, and 30% replacement
levels. Use of sourdough resulted in a decrease in phytic acid level (also in a decrease in the phytic acid to zinc mole ratio)
and corresponding increase in zinc bioavailability index when compared to the commercial sangak bread. The lowest phytic acid concentration and highest zinc bioavailability index were achieved when S. cerevisiae, L. plantarum, and Leu. mesenteroides were used at 30.0% dough replacement with sourdough. This study provides awareness about the negative impacts of higher phytic
acid level in the breads, which is particularly the case for sangak bread, and also provides a solution for such issue. 相似文献
108.
Farzan Rezaei 《Microelectronics Journal》2011,42(6):827-836
This paper presents an ultra low voltage, high performance Operational Transconductance Amplifier (OTA) and its application to implement a tunable Gm-C filter. The proposed OTA uses a 0.5 V single supply and consumes 60 μw. Employing special CMFF and CMFB circuits has improved CMRR to 138 dB in DC. Using bulk driven input stage results in higher linearity such that by applying a 500 mvp-p sine wave input signal at 2 MHz frequency in unity gain closed loop configuration, third harmonic distortion for output voltage is −46 dB and becomes −42.4 dB in open loop state for 820 mvp-p output voltage at 2 MHz. DC gain of the OTA is 47 dB and its unity gain bandwidth is 17.8 MHz with 20 pF capacitance load due to both deliberately optimized design and special frequency compensation technique. The OTA has been used to realize a wide tunable Gm-C low-pass filter whose cutoff frequency is tunable from 1.4 to 6 MHz. Proposed OTA and filter have been simulated in 0.18 μm TSMC CMOS technology with Hspice. Monte Carlo and temperature dependent simulation results are included to forecast the mismatch and temperature effects after fabrication process. 相似文献
109.
Mehdi Mohagheghi Karamatollah Rezaei Mohsen Labbafi Seyyed Mohammad Ebrahimzadeh Mousavi 《European Journal of Lipid Science and Technology》2011,113(6):730-736
Pomegranate seeds are by‐products of pomegranate juice industry. Since the seeds contain valuable oil that has nutritional and medicinal properties, they can be useful for food applications (especially in juice and beverage industries) as a functional agent. In this study, the possibility of producing a stable pomegranate‐seed‐oil‐in‐water emulsion to be used as a base formula for a new functional beverage was investigated. The influence of gum Arabic (GA) concentration (10.0, 12.5, and 15.0%, w/w) with a constant oil phase content (6.0% w/w) on the turbidity loss rate, emulsion stability index, and droplet size distribution was investigated. Turbidity loss rate was inversely proportional to the GA concentration for all the formulations studied here. Compared to other emulsions, emulsion with 15.0% w/w GA did not show a discernible cream layer during 42 days of storage. Emulsion with 15.0% w/w GA indicated the smallest polydispersity index during this period. The results of this study showed that it was possible to produce a relatively stable pomegranate‐seed‐oil‐in‐water emulsion for use as a functional agent in beverages. 相似文献
110.
Nanocrystalline magnesium oxide with high surface area was prepared by a simple precipitation method using pluronic P123 triblock copolymer (Poly(ethylene glycol)-block, Poly(propylene glycol)-block, Poly(ethylene glycol)) as surfactant. The prepared samples were characterized by X-ray Diffraction (XRD), N2 adsorption (BET), Fourier transform infrared spectroscopy (FTIR), Thermal, differential thermal gravimetric and differential thermal analyses (TG/DTG/DTA) and Scanning electron microscopy (SEM). The obtained results revealed that the addition of surfactant is effective to prepare magnesium oxide with high surface area and affects the morphology of the prepared samples. The results showed that the magnesium oxide calcined at different temperatures ranging from 600 to 800 °C possessed a high surface area in the range of 133.9–78.1 m2 g?1. In addition, the magnesium oxide prepared with the addition of surfactant showed a narrower pore size distribution compared to the sample prepared without the addition of a surfactant. 相似文献