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排序方式: 共有525条查询结果,搜索用时 31 毫秒
41.
A. Rezaei Shahreza A.H. Behravesh M. Bakhshi Jooybari E. Soury 《Polymer Engineering and Science》2010,50(12):2417-2424
This article presents a procedure to achieve a uniform outlet flow of molten polymer for a complex die profile with various thicknesses in die outlet cross section. According to a specific optimization methodology, the die was optimized based on varying die land length. The scope of this article includes: 3D flow simulation, optimization of the die velocity outputs based on the results of simulation process, and comparison of numerical predictions with the experimental data. Finally a significant result obtained by this work indicates higher ratio of the land length to the height of the zone with cross flow rather than the zones that are directly fed by the extruder. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers. 相似文献
42.
Previous gutting was applied to fresh kutum (Rutilus frissi kutum) to study the effects of cold smoking on the changes of rancidity and fatty acid (FA) content of the gutted and ungutted smoked kutum stored at room temperature (25 ± 2C) for 60 days. To do so, proximate (protein, ash, moisture and lipid), chemical (peroxide value [PV], thiobarbituric acid‐index [TBA‐i], total volatile basic nitrogen [TVB‐N] and FA profile) and pH analyses were carried out. The ungutting of kutum before smoking resulted in a higher degree of bacterial spoilage and oxidation during storage at room temperature, based on the results obtained from PV, TBA‐i, TVB‐N and FA content analyses. Moreover, pH as a critical factor on food spoilage showed a less decrease in smoked ungutted kutum during the 60‐day storage. It is concluded that the gutting of kutum before cold smoking is recommended as a pretreatment for storage at room temperature. 相似文献
43.
Polyaniline-supported acid salts such as polyaniline-hydrochloride, polyaniline-sulfate and polyaniline-nitrate were prepared by oxidation of aniline using ammonium persulfate as oxidizing agents. Polyaniline salts were used as catalyst for the preparation of β-acetamido ketones. Polyaniline-sulfate salt was found to be the best catalyst for the preparation of β-acetamido ketones. Present methodology offers several advantages, such as cheaper process, easy synthesis of stable catalyst, simple work-up procedure, and excellent activity with less amount of catalyst and in addition, the catalyst can be easily recovered after completion of the reaction and reusable without affecting its activity. 相似文献
44.
Quantum‐dot cellular automata (QCA) is one of the few alternative computing platforms that has the potential to be a promising technology because of higher speed, smaller size, and lower power consumption in comparison with CMOS technology. This letter proposes an optimized full comparator for implementation in QCA. The proposed design is compared with previous works in terms of complexity, area, and delay. In comparison with the best previous full comparator, our design has 64% and 85% improvement in cell count and area, respectively. Also, it is implemented with only one clock cycle. The obtained results show that our full comparator is more efficient in terms of cell count, complexity, area, and delay compared to the previous designs. Therefore, this structure can be simply used in designing QCA‐based circuits. 相似文献
45.
46.
Ali Charchi Mostafa Rezaei Siyamak Hossainpour Jamal Shayegh Sohrab Falak 《Journal of Materials Processing Technology》2010,210(14):2071-2080
In this study, a computational fluid dynamics (CFD) code was developed to calculate the filling pattern using volume of fluid (VOF) algorithm with donor–acceptor method for free surface simulation. This algorithm has been modified to include the pressure of the gas produced from foam degradation. For this purpose a heat transfer model and 2D foam degradation model were developed. In heat transfer model, radiation and conduction between foam and molten metal; and convection between gas and molten metal were considered. In order to evaluate the results of simulation, a bench scale casting apparatus was assembled and the casting was conducted in a transparent mold. The effect of several parameters such as coating thickness, foam density and vacuum level on the gap temperature, gap pressure and filling speed was studied with the developed software. It was found that the simulated results are in good agreement with experimental results. 相似文献
47.
Pouya Sirous Rezaei Ghasem Najafpour Darzi Hoda Shafaghat 《Korean Journal of Chemical Engineering》2010,27(3):919-924
A high performance thermostable α-amylase at low pH values has been synthesized. Sugarcane bagasse was hydrolyzed in a dilute acid solution and utilized as
carbon source for the growth of Aspergillus niger strain NCIM 548. Glucose, xylose and arabinose with the ratio of 1.0: 0.9: 0.3 (w/w/w) were detected in the hydrolyzate by
HPLC analysis. Optimization of the fermentation conditions for α-amylase production was performed by varying four influential parameters such as Sugarcane bagasse hydrolyzate (SBH), NH4Cl, pH and incubation time using a central composite design (CCD) under response surface methodology (RSM). The optimum values
of SBH, NH4Cl, pH and incubation time were 20.49, 2.34 g/l, 5.65 and 76.67 h, respectively. The acido-thermophilic enzyme showed maximum stability at 70°C and pH value of 4. The rate
constant, K
m
and maximum reaction rate, V
max
were 18.79 g/l and 15.85 g/l·min, respectively. 相似文献
48.
Karamatollah Rezaei Tong Wang Lawrence A. Johnson 《Journal of the American Oil Chemists' Society》2002,79(8):803-808
Hydrogenated soybean oil, referred to as soywax by candle makers, is a renewable and biodegradable alternative to paraffin
wax in candle manufacturing. Soywax was investigated for its tendency to produce soot as well as potentially harmful organic
volatiles (acrolein, formaldehyde, and acetaldehyde) during combustion. Beeswax and paraffin candles were used as references.
A considerable amount of soot was produced from the combustion of paraffin candles, but little or none was observed from soywax
candles. Compared to paraffin candles, soywax candles burned at a significantly slower rate and required less air. Small amounts
of formaldehyde were detected and quantified in the fumes of burning paraffin candles. However, formaldehyde, peaks found
in the chromatograms of soy- and beeswax candles were similar to or slightly higher than that of the blank. Since soywax candles
exhibited burning properties similar to those of beeswax candles, soywax shows promise in candle applications. 相似文献
49.
M. Hekmatfar Sh. Moshayedi S.A. Ghaffari H.R. Rezaei F. Golestani-Fard 《Materials Letters》2011,65(23-24):3421-3423
Zirconia/Hydroxyapatite composites containing 20–50 wt.% 8YSZ were prepared on Ti/TiO2 substrates by electrophoretic deposition (EPD)/micro-arc oxidation (MAO) process. Titania, as an inner layer, was grown on the Ti plates using MAO treatment in order to form a strong join between substrate and HAp. These composites were produced by EPD in ethanol containing ZrO2/HAp particles at 50, 100 and 150 V in 1 min. As-prepared samples were sintered at 900, 1100 and 1300 °C. HAp, β-TCP, CaZrO3 phases were identified using X-ray diffractometry analysis (XRD). Scanning electron microscopy (SEM) utilized to study the surface morphology indicated a crack free microstructure at 1300 °C. 相似文献
50.
In the current study, formulation design and development of a novel pectin-based functional gel were investigated. Amidated low methoxyl pectin (ALMP), high methoxyl pectin (HMP), sorbitol, inulin, rebaudioside-A, gardenia, phloridzin, quercetin, apple flavor, and calcium chloride (as its dihydrated salt) were selected as general ingredients. Response surface methodology was applied to design different formulations and to investigate on their experimental responses. The oscillatory tests were carried out in 2 stages with ALMP, HMP, sorbitol, and inulin as the variables of the 1st stage and ALMP and calcium chloride as the variables of the 2nd stage. Results of the 1st stage indicated relatively similar behaviors throughout the frequency range applied for all of the samples studied (true gels). However, magnitudes of the 5 rheological parameters of this study (storage modulus, loss modulus, loss tangent, complex modulus, and complex viscosity) were affected by different variables (ALMP, HMP, inulin, and sorbitol concentrations). Experimental results confirmed that sorbitol could be omitted from the formula while inulin and HMP could be used at their highest levels studied. At the 2nd stage, only 2 formulas indicated a strong gel behavior and other formulas showed typical behaviors of weaker gels or those of the concentrated solutions. At the conclusion of this study, a finished gelled product formula was suggested with the application of the best levels of the ingredients. The resultant gel was found to be set rapidly with no syneresis and showed a potential to be considered as a functional gelled dessert. 相似文献