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排序方式: 共有76条查询结果,搜索用时 15 毫秒
1.
Aziz Tekin Melih Cizmeci Hulya Karabacak Muammer Kayahan 《Journal of the American Oil Chemists' Society》2002,79(5):443-445
Trans FA (TFA), solid fat contents (SFC), and slip melting points of 12 different tub and stick margarines marketed in Turkey were
examined in this study. No trans isomers were found in four margarines, which suggests they were formulated from interesterified or blended fats and oils.
The products with no TFA generally had more short-chain saturated FA, which suggests coconut oil-based oil components. TFA
content of the other 10 products varied from 7.7 to 37.8%. Compared to the products formulated in North America, Turkish margarines
contain more TFA and have higher SFC. 相似文献
2.
In this study, an experimental study was carried out to examine the effect of different clearances on smooth-sheared depth, burr height and blanking force. Aluminium sheet metals with 0.8, 1, and 1.5 mm thicknesses were used in the experiments. These experiments were carried out in circular blanking dies to 6, 8, 10, and 12 mm diameters. Six different clearances (0.009, 0.064, 0.12, 0.175, 0.231 and 0.287 mm) were used for every material and diameter. The results of the experiment show that burr, smooth-sheared and punch force is strongly related to the clearance value. The results are in agreement with the results of previous theoretical and experimental work in the literature. 相似文献
3.
低噪声APD偏置电路 总被引:2,自引:0,他引:2
1APD的特性雪崩光电检测器 (APD)和PIN二极管通常被作为接收器用于光通信中。其中APD适合于高灵敏度和高带宽的光接收电路。但这种器件在工作时需要施加一个反向结压 ,这样 ,当接收到射线时产生的电子空穴对会被外加电场收集并转换为电流 ,其电流强度正比于射线强度。另外 ,工作时施加在器件上的反向偏置电压会引发雪崩效应 ,其雪崩增益可通过改变偏压来进行调节。这就有可能对光纤接收器的增益进行优化。然而 ,要得到满意的雪崩增益 ,就必须给APD提供一个比较高的反向偏压。很多APD需要40V~60V的偏压 ,有些器件… 相似文献
4.
Tulay Y. İnan Emel Yıldız Birsen Karaca Hacer Dogan Alican Vatansever Muhammed Nalbant Koray Eken 《Journal of materials science. Materials in medicine》2014,25(8):2027-2039
We produced UV curable lenses with properties blocking short wave UV light. In the UV-curable formulations, we used an oligomer (Ac-PEEK) with another urethan oligomer (Mw = 2000). Radically active, molecular weight controlled Ac-PEEK was obtained by reacting 2-hydroxyl ethyl methacrylate with molecular- weight- controlled and isocyanate terminated PEEK (Mn = 4500). We characterized all synthesized monomer, oligomer and optical materials with UV/Vis spectrophotometer with interferogram, elemental analyser, mass spectrophotometer, proton nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermal gravimetric analyzer, differential scanning calorimeter, scanning electron microscopy and gas chromatography. Results suggested that newly synthesized oligomer with the structure of PEEK absorbs short wave UV-light. Ageing tests [ISO 11979-5, Ophthalmic implants—intraocular lenses (IOL)—Part 5: Biocompatibility] performed on the IOL materials were successful. High contact angle of the obtained lenses suggests that all lenses were hydrophobic and SEM results revealed that lenses are morphologically homogeneous. Based on all positive properties just mentioned, we safely conclude that the lenses produced in this study are very promising for IOL production. 相似文献
5.
Mevlut Fatih Peker Ömer Necati Cora Muammer Koç 《International Journal of Hydrogen Energy》2011,36(23):15427-15436
Tribological variations, surface conditions (roughness, hardness, coating) and surface interactions between micro-stamping dies and bipolar plate blanks play a critical role in determining the surface quality, channel formation and precision of bipolar plates. This study is aimed to understand the cause, mechanism and consequences of interactions between micro-stamping process conditions and bipolar plate quality. A total of 2000 repeated micro-stamping of 51 μm-thick uncoated and 1 μm-thick ZrN coated SS316L sheet blanks into an array of 750 μm micro-channels were performed using 175-220 kN force levels with constant stamping speed of 1 mm/s. Microscopic examinations were conducted periodically on both die and coated & uncoated plate surfaces to observe topographic variations. In addition, corrosion and contact resistance tests were carried out in the same intervals. Analysis of variance (ANOVA) technique was used to determine the significance of the process parameters on channel height, roughness, corrosion and contact resistance differences. The results revealed similar roughness trends for die and plate surfaces during 2000 micro-stampings. ZrN coating with 1 μm thickness dramatically improved corrosion and contact resistance behavior of plates. 相似文献
6.
7.
高亮度LED的高效率电流驱动电路 总被引:5,自引:0,他引:5
Mehmet Nalbant 《电子产品世界》2005,(9):101-103
本文介绍调整高亮度LED电流的简单电路.它包括一个流行的高集成降压开关稳压器,此开关稳压器能精确地控制LED电流.MAX5035是工作在125KHz固定频率的DC/DC转换器,其宽范围的输入电压(7.5V~76V)特别适合于汽车应用.对于亮度控制,它能实现模拟(线性调光)或低频占空比调制(PWM调光). 相似文献
8.
Melih Cizmeci Anar Musavi Aziz Tekin Muammer Kayahan 《European Journal of Lipid Science and Technology》2009,111(6):607-611
Soybean oil was hydrogenated with a carbon‐supported ruthenium catalyst (Ru/C) at 165 °C, 2 bar H2 and 500 rpm stirring speed. Reaction rates, trans isomer formation, selectivity ratios and melting behaviors of the samples were monitored. No catalytic activity was found for the application of 10 ppm of the catalyst, and significant catalytic activity appeared at >50 ppm of active catalyst. The catalyst concentration had an effect on the reaction rate of hydrogenation, but the weight‐normalized reaction rate constant (kc) was almost independent of the catalyst concentration at lower iodine values. Ru/C generated considerable amounts of trans fatty acids (TFA), including high amounts of trans 18:2, and also stearic acid, due to its very non‐selective nature. The selectivity ratios were found to be low and varied between 1.12 and 4.32 during the reactions. On the other hand, because of the low selectivity, higher slip melting points and solid fat contents at high temperatures were obtained than those for nickel and palladium catalysts. Another different characteristic of this catalyst was the formation (max 1.67%) of conjugated linoleic acid (CLA) during hydrogenation. Besides, CLA formation in the early stages of the reactions did not change very much with the lower iodine values. 相似文献
9.
Use of FEM in the metal forming process has been a proven analysis tool. Two-dimensional FEA for simplified sections can help to reduce time and cost in part, tooling and process design in tube hydroforming technology as it is a relatively new process, and the existing experience and knowledge base is not as broad as with other forming processes. Some case studies are presented to demonstrate the use of two-dimensional FEA in the hydroforming process. Upon verification through comparison of FEA predictions with experimental results, further planned simulations are conducted to generate simple design rules on geometrical and process parameters. 相似文献
10.
Metal particles coating is extensively used for surface coating a wide range of application including thermal management of electronics, concentrating photovoltaics, sensors and nuclear power plants. Both micro and nano-scale surfaces have been proven to show an enhanced two-phase heat transfer performance by varying surface properties like area, wettability, and roughness. To combine the unique features of both micro and nano-scale surface coatings, this study presents the design, synthesis, and characterization of new hybrid micro-nano scale surface coating by a new two steps approach. Five different types of surfaces; namely, plain nanocoated (PNC), uniform micro-porous (UMP), uniform hybrid micro-nano porous (UHMNP), 2-D modulated microporous (MMP) and modulated hybrid micro-nano (MHMNP) surfaces were fabricated. A new two steps approach of hot-pressing followed by nucleate boiling is used for the fabrication of these surfaces. Successful coating of hybrid micro-nano scale coating was achieved. Considering the critical surface properties of micro and nanoscale coatings, new hybrid micro-nano surfaces have been characterized for SEM, wettability, roughness test. The comparative analysis of these new hybrid coating is also performed with micro coated and uncoated surfaces. With the coating of nanoparticles, the average roughness of PNC surface increased by 4.67 times and that of hybrid micro-nano particle surface by 2.3 times. The deposition of nanoparticles resulted in an increase in contact angle for PNC surface, while the contact angle of hybrid micro-nano surfaces decreases from 126.4° to 82.1°. 相似文献