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排序方式: 共有1174条查询结果,搜索用时 0 毫秒
971.
Adnan Akkurt 《Journal of Materials Engineering and Performance》2011,20(6):960-968
Component surface quality and selection of the optimum material are the main factors determining the performance of components
used in machine manufacturing. The level of hole surface quality can be evaluated by the measurements regarding surface roughness,
micro-hardness, and cylindricity. In this study, data had been obtained for different hole drilling methods. The characteristics
of materials obtained after applications were compared for different hole-finishing processes to identify best hole drilling
method. AISI 304 austenitic stainless steel material was used. Surface finishing of holes were performed using drilling, turning,
reaming, grinding, honing, and roller burnishing methods. The results of the study show that the roller burnishing method
gives the best results for mechanical, metallurgical properties, and hole surface quality of the material. On the other hand,
the worst characteristics were obtained in the drilling method. 相似文献
972.
Proteins control all biological functions in living species. Protein structure is comprised of four major classes including all-α class, all-β class, α+β, and α/β. Each class performs different function according to their nature. Owing to the large exploration of protein sequences in the databanks, the identification of protein structure classes is difficult through conventional methods with respect to cost and time. Looking at the importance of protein structure classes, it is thus highly desirable to develop a computational model for discriminating protein structure classes with high accuracy. For this purpose, we propose a silco method by incorporating Pseudo Average Chemical Shift and Support Vector Machine. Two feature extraction schemes namely Pseudo Amino Acid Composition and Pseudo Average Chemical Shift are used to explore valuable information from protein sequences. The performance of the proposed model is assessed using four benchmark datasets 25PDB, 1189, 640 and 399 employing jackknife test. The success rates of the proposed model are 84.2%, 85.0%, 86.4%, and 89.2%, respectively on the four datasets. The empirical results reveal that the performance of our proposed model compared to existing models is promising in the literature so far and might be useful for future research. 相似文献
973.
Synthesis of novel copper nanoparticles/ternary polymer blend nanocomposites and their structural,thermal and rheological properties and AC impedance
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Uzma Khalil Sajjad Haider Muhammad Saleem Khan Adnan Haider Rawaiz Khan Abdulaziz A Alghyamah Waheed A Almasry Mohamed Bououdina 《Polymer International》2017,66(8):1182-1189
Copper nanoparticles (Cu NPs)/ternary polymer blend nanocomposites were synthesized via a solution‐casting technique. The nanocomposites were studied for their structural, thermal, rheological and electric properties. Scanning electron micrographs and atomic force micrographs showed no phase separation between the polymers, a narrow size distribution of Cu NPs (in the range 25–43 nm) and good dispersion of Cu NPs in the polymer matrix. Energy‐dispersive X‐ray analysis confirmed the presences of Cu in the matrix. X‐ray diffraction data showed a characteristic face‐centred cubic architecture for Cu unit cell and interaction of the Cu NPs with oxygen‐carrying polymers. Thermogravimetric analysis showed an increase in the degradation temperature (from 254 to 268 °C) and three‐step degradation of the nanocomposites. Rheological analysis showed an increase in the complex viscosities and storage modulus for the nanocomposites. AC impedance studies showed increased ionic conductivities and decreased bulk resistance for the nanocomposites. All these studies suggested interactions between Cu NPs and polymer matrix and the formation of a network structure. © 2017 Society of Chemical Industry 相似文献
974.
975.
Hatim M. Behairy Waleed S. Alrobian Adnan A. Alghammas Brian R. Suter 《Wireless Personal Communications》2014,77(4):3143-3157
In certain environments, the use of mobile phones must be curtailed for the sake of security or out of respect for others. We present a novel method for selectively controlling mobile phone services in such areas using a base station controller and a sequence of detection steps to identify when the mobile device is within the coverage area. A prototype for the method has been developed using commercial off-the-shelf and custom designed hardware and software subsystems. Key components in the prototype system are two directional antennas located at the entry to the controlled area with one antenna facing outwards and the other inwards. By using the proposed detection method, the base station controller is able to detect when a mobile station enters or leaves the controlled area. Experiments using a variety of detection sequences by the two directional antennas and associated white- and blacklists of allowable and disallowed devices, respectively, confirm that the prototype system is able to effectively control the use of mobile devices within the coverage area. 相似文献
976.
This paper presents CO2-toluene (CO2-C7H8) binary mixture as working fluid to enhance the energetic and exergetic performance of CO2 bottoming power cycles in warm ambient conditions. A criterion for selection of CO2-based binary mixture is defined, and 0.9 CO2/0.1 C7H8 composition is decided based on the required minimum cycle temperature compatible with ambient conditions. Bottoming simple regenerative cycle (BSRC) and bottoming preheating cycle (BPHC) configurations are selected, and their realistic operating conditions are determined based on sensitivity analysis. The performance of bottoming cycles using CO2-C7H8 binary mixture is compared with the bottoming cycles using pure CO2 as working fluid at different ambient temperatures. It is observed that the cycles operating with pure CO2 can only perform better at lower ambient temperature conditions, whereas, at the increased ambient temperatures, bottoming cycles with CO2-C7H8 binary mixture outperform and produce significant gains in exergetic and energetic performance compared with pure CO2 bottoming cycles. A maximum gain of exergetic efficiency for BSRC and BPHC observed is 26.83% and 18.71%, respectively, at an operating ambient temperature of 313 K, whereas an overall gain in energetic efficiencies for BSRC and BPHC observed is 28.92% and 10.12%, respectively. Taking into consideration thermodynamic performance, overall UA (product of overall heat transfer coefficient and heat transfer area for the heat exchanger) and specific investment cost, BPHC configuration is suggested as reasonable choice for higher ambient temperature conditions. 相似文献
977.
978.
Ciprian Lazarescu Angela Dale Adnan Uzunovic Colette Breuil Stavros Avramidis 《Holz als Roh- und Werkstoff》2011,69(4):573-578
The research was aimed to establish whether dielectric heating at radio frequencies (RF)??an alternative method to ozone-depleting methyl bromide fumigation and to convective heating??could bring green lodgepole pine boards infested with pinewood nematodes (PWN) to pasteurization requirements. Artificially infected specimens were treated using a laboratory RF oven and post-treatment nematode survival levels were assessed. Both tested combinations of?56°C/30?min and 60°C/15?min were effective in eradicating PWN. A?power density of 50?kW/m3 maintained for 75?minutes fully pasteurized all the tested boards and proved to be the right combination if no temperature sensors are used. The data gathered supports the idea that pasteurization by RF heating is a reliable and swift alternative treatment to fumigation and convective heat treatment. 相似文献
979.
Material Removal Rate,Kerf, and Surface Roughness of Tungsten Carbide Machined with Wire Electrical Discharge Machining 总被引:3,自引:0,他引:3
Aqueel Shah Nadeem A. Mufti Dinesh Rakwal Eberhard Bamberg 《Journal of Materials Engineering and Performance》2011,20(1):71-76
In this article, the effects of varying seven different machining parameters in addition to varying the material thickness
on the machining responses such as material removal rate, kerf, and surface roughness of tungsten carbide samples machined
by wire electrical discharge machining (WEDM) were investigated. The design of experiments was based on a Taguchi orthogonal
design with 8 control factors with three levels each, requiring a set of 27 experiments that were repeated three times. ANOVA
was carried out after obtaining the responses to determine the significant factors. The work piece thickness was expected
to have a major effect on the material removal rate but showed to be significant in the case of surface roughness only. Finally,
optimization of the machining responses was carried out and models for the material removal rate, kerf, and surface roughness
were created. The models were validated through confirmation experiments that showed significant improvements in machining
performance for all investigated machining outcomes. 相似文献
980.
Adnan Ali Kamran Ali Ki-Rin Kwon Myung Taek Hyun Kyung Hyun Choi 《Journal of Materials Science: Materials in Electronics》2014,25(2):1097-1104
Graphene-based composites represent a new class of materials with potential for many applications. Metal, semiconductor, or any polymer properties can be tuned by attaching it to graphene. Here, a new route for fabrication of graphene based composites thin films has been explored. Graphene flakes (<4 layers) and a well-known semiconductor zinc oxide (ZnO) (<50 nm particle size) have been dispersed in N-methylpyrrolidone and ethanol, respectively. Thin film of graphene flakes is deposited and decorated with ZnO nanoparticles to fabricate graphene/ZnO composite thin film on silicon substrate by electro hydrodynamic atomization technique. Graphene/ZnO composite thin film has been characterized morphologically, structurally and chemically. To investigate electronic behavior of the composite thin film, it is deployed as cathode in a diode device i.e. indium tin oxide/poly (3,4-ethylenedioxythiophene) poly (styrenesulfonate)/polydioctylfluorene-benzothiadiazole/(graphene/ZnO). The J–V analysis of diode device has shown that at voltage of 1 V, the current density in organic structure is at low value of 4.69 × 10?3 A/cm2 and when voltage applied voltage is further increased; the device current density has increased by the order of 200 that is 1.034 A/cm2 at voltage of 12 V. 相似文献