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排序方式: 共有165条查询结果,搜索用时 724 毫秒
21.
During designing a new axial flux permanent magnet free rod rotor synchronous motor, it is important to know before hand in which phase the largest angular velocity can occur, what is the ways to reduce the power consumption, how to achieve to increase or decrease the rotation speed by changing the core geometry. Therefore, presenting these preliminary information that are necessary for the design of a free rod rotor synchronous motor to the researchers is the aim of this work. In this respect, this study presents the design and geometrical dimensions of the stator for a new synchronous motor which is an axial flux permanent magnet free rod machine with three, four, five and six phases. This type of motors are an innovative approach especially for the applications used in industrial stirrers. Each type of stator is designed such that it has an appropriate number of phases. The rotating magnetic field over the stator is established by a PIC based microcontroller feeding the interface circuit to the stator wounds. The maximum angular speeds of bar magnet rotors with four different lengths and masses are calculated theoretically and determined experimentally. In addition, the effects of the distance between the rotor and stator, the angular speed of the rotor within the limits of the operation, and the volume of the liquid to be stirred to the power applied are investigated. Furthermore, the effects of the lengths and angular speeds of the bar magnet rotors to the distance between the rotor and stator are determined. In the light of the information obtained and taking into account the power used, the most appropriate parameters and variables such as the stator geometry changing with the phase used, the length of rotor, the distance between the rotor and stator and the angular speeds of rotor are determined. 相似文献
22.
Energy is one of the indispensable factors regarding the assurance of social prosperity and economic development of a country. The developing countries struggle to obtain energy sources reliable in the long term to complete their economic development, and the developed countries struggle to get them to keep their present prosperity levels. Coal seems to continue its indispensable position among the other energy sources for many years because of its production in more than 50 countries, the least effect it has from the price fluctuation and its usage lifespan of more than 200 years. The countries that are aware of it have investments in mining fields in the countries rich in coal reserves, and they continue investing considerable amount of money. 相似文献
23.
Comprising 65–70% of the world's oil reserves, the Gulf States (Saudi Arabia, Iran, Iraq, Kuwait, UAE and Qatar) are key countries for the solutions to the energy supply matters of the world. Free flow of oil to the world markets from Gulf region is an indispensable part of the major security issues. The Middle East has had mainly security related problems such as Arab–Israeli wars and conflicts, Arab–Iranian war and conflicts, Arab–Arab war and conflicts, US–Gulf wars and conflicts and more recently radicalism and terrorist attacks. Energy supply security requires the enhancement of the peace and cooperation between countries instead of competition. Preventive policy approaches are more suitable to address energy supply matters. Preventive strategy might be possible with the active participation of NATO within the “out of area” type operations to the Middle East and quite possibly indirectly to the Asia-Pacific regions. Religious and ethnic radicalism and terrorist attacks has also direct effects over oil supply security matters. 相似文献
24.
Cebrail Çiflikli A. Tuncay Özşahin A. Çağrı Yapici 《Wireless Personal Communications》2009,51(2):221-229
The many advantages responsible for the widespread application of orthogonal frequency division multiplexing (OFDM) systems
are limited by the multipath fading. In OFDM systems, channel estimation is carried out by transmitting pilot symbols generally.
In this paper, we propose an artificial neural network (ANN) channel estimation technique based on levenberg-marquardt training
algorithm as an alternative to pilot based channel estimation technique for OFDM systems over Rayleigh fading channels. In
proposed technique, there are no pilot symbols which added to OFDM. Therefore, this technique is more bandwidth efficient
compared to pilot-based channel estimation techniques. Also, this technique is making full use of the learning property of
neural network. By using this feature, there is no need of any matrix computation and the proposed technique is less complex
than the pilot based techniques. Simulation results show that ANN based channel estimator gives better results compared to
the pilot based channel estimator for OFDM systems over Rayleigh fading channel. 相似文献
25.
We have developed a nanoreactor, sample holder and gas system for in-situ transmission electron microscopy (TEM) of hydrogen storage materials up to at least 4.5 bar. The MEMS-based nanoreactor has a microheater, two electron-transparent windows and a gas inlet and outlet. The holder contains various O-rings to have leak-tight connections with the nanoreactor. The system was tested with the (de)hydrogenation of Pd at pressures up to 4.5 bar. The Pd film consisted of islands being 15 nm thick and 50-500 nm wide. In electron diffraction mode we observed reproducibly a crystal lattice expansion and shrinkage owing to hydrogenation and dehydrogenation, respectively. In selected-area electron diffraction and bright/dark-field modes the (de)hydrogenation of individual Pd particles was followed. Some Pd islands are consistently hydrogenated faster than others. When thermally cycled, thermal hysteresis of about 10-16 °C between hydrogen absorption and desorption was observed for hydrogen pressures of 0.5-4.5 bar. Experiments at 0.8 bar and 3.2 bar showed that the (de)hydrogenation temperature is not affected by the electron beam. This result shows that this is a fast method to investigate hydrogen storage materials with information at the nanometer scale. 相似文献
26.
Hasan Kurtaran Tuncay Erzurumlu 《The International Journal of Advanced Manufacturing Technology》2006,27(5-6):468-472
During the production of thin shell plastic parts by injection molding, warpage depending on the process conditions is often
encountered. In this study, efficient minimization of warpage on thin shell plastic parts by integrating finite element (FE)
analysis, statistical design of experiment method, response surface methodology (RSM), and genetic algorithm (GA) is investigated.
A bus ceiling lamp base is considered as a thin shell plastic part example. To achieve the minimum warpage, optimum process
condition parameters are determined. Mold temperature, melt temperature, packing pressure, packing time, and cooling time
are considered as process condition parameters. FE analyses are conducted for a combination of process parameters organized
using statistical three-level full factorial experimental design. The most important process parameters influencing warpage
are determined using FE analysis results based on analysis of variance (ANOVA) method. A predictive response surface model
for warpage data is created using RSM. The response surface (RS) model is interfaced with an effective GA to find the optimum
process parameter values. 相似文献
27.
Tuncay Simsek Mustafa Baris Arun K. Chattopadhyay Sadan Ozcan Adnan Akkurt 《Transactions of the Indian Institute of Metals》2018,71(8):1885-1896
To improve mechanical properties of S2355JR carbon steel, pre-synthesized ZrB2 nanocrystals were used to coat the metal surface by laser cladding using 2000 W CO2 laser. ZrB2 nanocrystals were synthesized by mechanochemical process. The effect of laser power on the coating layers was examined for optimizing the most effective coating conditions. Microstructural studies were carried out using optical microscope, scanning electron microscope and X-ray diffraction to analyze phase structures of the coated layers. Mechanical characteristics of the laser coated layers were evaluated by studying microhardness, wear and scratch resistance properties. Maximum hardness of the coated layers was observed while cladding with 75 and 125 W laser powers, when other processing parameters and conditions were kept at optimum levels. EDS analysis of these laser cladded layers indicated the formation of complex boro-nitrides, nitrides and carbides of Zr and Fe that contributed to vast increase in hardness of the laser-clad coating on S2355JR steel. Depending upon the laser powers used, the thickness of the coated layers was found to be in the range of 15–37 µm. The wear and micro-scratch tests results revealed significant improvement in wear properties. 相似文献
28.
Ensuring the effective thermal insulation in regions, where the cooling requirement of building with respect to heating requirement is dominant, is very important from the aspect of energy economy. In this study, the influence of thermal insulation on the building cooling load and the cooling system in case of air-conditioning by an all-air central air-conditioning system was evaluated for a sample building located in Adana, based on the results of three different types of insulation (A, B and C-type buildings) according to the energy efficiency index defined in the Thermal Insulation Regulation used in Turkey. The operating costs of the air-conditioning system were calculated using cooling bin numbers. Life-cycle cost analysis was carried out utilizing the present-worth cost method. Results showed that both the initial and the operating costs of the air-conditioning system were reduced considerably for all three insulation thicknesses. However, the optimum results in view of economic measurements were obtained for a C-type building. The thickness of thermal insulation for the buildings in the southern Turkey should be determined according to the guidelines for a C-type building. 相似文献
29.
Can Tuncay Ak&inodot nn Ayhan Bekleyen Mü cahit Y&inodot ld&inodot r&inodot m 《建筑学研究前沿(英文版)》2016,5(3):360
The traditional houses of the residential areas in and around Siirt in the southeastern region of Turkey are notable because of their interesting forms. The most successful examples are the "truncated pyramidal-shaped houses" that have existed for centuries and are unique to the locality; however, these forms are demolished rapidly. In this study, the structures of small- scale settlements in Siirt province and its environs have been evaluated to highlight the cultural aspects of the region. The subject of this research is to investigate the design principles of the rural houses constructed in vernacular style to raise international awareness of the need to preserve vernacular architecture. Surviving examples have been examined in terms of multiple case approach by their forms, spatial compositions, changes in their forms over time, their layouts in urban and rural areas, the construction techniques used to produce them from material production through implementation, the composition of the living space and its uses, their differences or similarities to other houses in the region and their aesthetic details. The research reveals that the design principles of traditional rural architecture offer the use of local material and techniques in a unique way that promote highlights to the future. 相似文献
30.
Ali Tuncay Ozyilmaz Gul Ozyilmaz Ercan Yılmaz Nureddin Çolak 《Korean Journal of Chemical Engineering》2008,25(4):846-853
The electrochemical synthesis of poly(o-anisidine) (POA) was achieved on brass (CuZn) electrode by applying two scan rates
(50 and 20 mVs−1). The synthesized polymer films were strongly adherent and homogeneous in both cases. Their corrosion performance was investigated
by AC impedance spectroscopy (EIS) technique, anodic polarization plots and open circuit potential-time curves, in 3.5% NaCl
solution. It was clearly seen that poly(o-anisidine) films provided a significant physical protection for longer exposure
time. It was shown that polymer film coated at high scan rate (CuZn/POA-H) exhibited better barrier property against the attack
of corrosive agents when compared with polymer film obtained at low scan rate (CuZn/POA-L). It was found out that poly(o-anisidine)
film synthesized at high scan rate caused a significant increase in corrosion resistance by its catalytic behavior on formation
of protective oxide layers on the surface in longer time. 相似文献