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排序方式: 共有197条查询结果,搜索用时 31 毫秒
1.
This article presents a method that can be applied to molten AA-6101 alloy to improve electrical properties of the aluminium part of the optical ground wire (OPGW) used in overhead transmission lines to protect phase conductors from lightning strike and to transmit signals and data. AA-6101 alloy in casting of the log as 6 m length and 178 mm diameter for extrusion has been inoculated by AlB2 to decrease detrimental effects of Cr, Ti, V, and Zr on the conductivity of the material. After inoculation, improved billets were extruded as 9.5 mm diameter feedstock. Required wires drawn from the feedstock according to the construction types of OPGW to be tested were exposed to aging at 175°C, 6 h (T-8). Upon completion of the back-twist and performing-type stranding process, resistance, and short-circuit current capacity and breaking load of the OPGW 88/44 constructions with other metal combinations have been examined and tested to show improvement. Results are summarized in tables and graphically. 相似文献
2.
Laurus nobilis L., commonly known as daphne tree, is an evergreen that belongs to the Lauraceae family. Daphne trees produce grape-sized
shiny purplish berries having three parts: flesh, skin, and an inner kernel (single seed). This study examines supercritical
CO2 (SC-CO2) extraction of oil from daphne seeds. The oil yield of ground seeds varied from 14 to 28% depending on the method and particle
size used for oil recovery. Yields were similar for both petroleum ether and SC-CO2 extraction. The extraction yield decreased significantly with increasing particle size. The amount of extract collected increased
exponentially with increasing SC-CO2 pressure. The highest extraction yield was obtained at the highest temperature studied, 75°C. More than 45% of the oil was
lauric acid. SC-CO2 is a viable technique to obtain high-purity L. nobilis L. seed oil, which is a potential ingredient for the cosmetic industry. 相似文献
3.
Bilal Demirel Nihat B. İnaner Derya U. Gezer Fugen Daver Ali Yaras Fatih Akkurt 《Polymer Engineering and Science》2021,61(7):2043-2054
Polyethylene terephthalate (PET)/nano-hydroxyapatite (nHAp) composite granules were obtained using twin-screw extruder. Preforms were prepared by injection molding and then PET/nHAp bottles were produced by blow molding. For PET bottles with nHAp, the migration amounts of carboxylic acid (COOH), acetaldehyde (AA), diethylene glycol (DEG), and isophthalic acid (IPA); glass transition temperature (Tg); melting temperature (Tm); and the maximum crystallization temperature (Tcry) were measured. The load-carrying capacity, burst strength, stress cracking, and regional material distribution tests were carried out on the bottles. X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and ultraviolet transmittance analyses were conducted to explain the changes in mechanical, chemical, physical properties, and light transmission of bottles. It was found out that the COOH amount increased and the AA content decreased with increasing nHAp amount. On the other hand, no change was observed in the amounts of DEG and IPA. Although the mechanical properties such as load-carrying capacity and burst strength of the bottles have improved, it has been determined that the standard environmental stress crack resistance test procedure cannot be applied to such a composite. Experimental findings indicate that nHAp disrupts the chemical structure of PET and it isolates harmful chemicals such as AA by forming intermolecular bonds. Moreover, with the addition of up to 0.8% nHAp, PET bottles block the light transmission approximately 80% within 400–700 nm wave length zone. The study demonstrates that the PET/nHAp composite bottles can be used in the food industry, particularly in the packaging of milk and milk products which are vulnerable to light exposure. 相似文献
4.
Uur Sar Sedat Aan lhan Aksoy Kutalm
Güven Nermin Kahveci 《Journal of Materials Processing Technology》2004,150(3):208-214
In this systematic study, dispersion-strengthening effect of the Cu–25.91Mn (wt.%), Cu–26.62Mn–8.99Al (wt.%), Cu–22.17Mn–12.32Zn (wt.%) ingot alloys have been investigated. Samples were homogenized at a high fixed temperature in different periods and cooled with different cooling rates. After processes, microanalysis of the samples were interpreted by using scanning electron microscope (SEM) and weight percentages of the elements of the occurrence phases in the samples obtained by using electron dispersion spectroscopy (EDS) technique. Additionally, some characteristic properties of the heat treated samples with different conditions of Cu–Mn, Cu–Mn–Al, Cu–Mn–Zn ingot alloys were also discussed. 相似文献
5.
C. Başyigit Iskender Akkurt S. Kilincarslan A. Beycioglu 《Neural computing & applications》2010,19(4):507-513
The compressive strength of heavyweight concrete which is produced using baryte aggregates has been predicted by artificial
neural network (ANN) and fuzzy logic (FL) models. For these models 45 experimental results were used and trained. Cement rate,
water rate, periods (7–28–90 days) and baryte (BaSO4) rate (%) were used as inputs and compressive strength (MPa) was used as output while developing both ANN and FL models.
In the models, training and testing results have shown that ANN and FL systems have strong potential for predicting compressive
strength of concretes containing baryte (BaSO4). 相似文献
6.
7.
With the ever-increasing demand for wireless real-time services and continuing emergence of new multimedia applications especially for mobile users, it is necessary for the network to support various levels of quality of service (QoS) while maximizing the utilization of scarce and expensive wireless channel resources. Considering this fact, a new TDMA/FDD MAC protocol integrating a novel QoS management algorithm and multi-beam Directional Antennas (DAs) to efficiently exploit wireless resources has been developed and presented in this paper. It supports all ATM CBR, VBR, ABR and UBR service classes by adopting a well-managed dynamic guarantee-based QoS scheduling algorithm. The work mainly aims at increasing the wireless system throughput as well as improving the call-blocking ratios and end-to-end delays for real-time applications. This seamless communication enables both handling real-time multimedia traffics in a fair manner and granting call requests on the basis of the connection types. The system has been developed, modeled and simulated using OPNET Modeler. The simulation results show that the QoS-aware TDMA/FDD MAC with multi-beam DAs has substantially increased the system throughput and that the call-blocking ratio has been reduced from 86% to 18%, when the proposed MAC with 8-Beam antennas is employed instead of the regular MAC. 相似文献
8.
Sedat Ozer Author Vitae Chi H. Chen Author Vitae Author Vitae 《Pattern recognition》2011,44(7):1435-4123
In this study, we introduce a set of new kernel functions derived from the generalized Chebyshev polynomials. The proposed generalized Chebyshev polynomials allow us to derive different kernel functions. By using these polynomial functions, we generalize recently introduced Chebyshev kernel function for vector inputs and, as a result, we obtain a robust set of kernel functions for Support Vector Machine (SVM) classification. Thus in this study, besides clarifying how to apply the Chebyshev kernel functions on vector inputs, we also increase the generalization capability of the previously proposed Chebyshev kernels and show how to derive new kernel functions by using the generalized Chebyshev polynomials. The proposed set of kernel functions provides competitive performance when compared to all other common kernel functions on average for the simulation datasets. The results indicate that they can be used as a good alternative to other common kernel functions for SVM classification in order to obtain better accuracy. Moreover, test results show that the generalized Chebyshev kernel approaches to the minimum support vector number for classification in general. 相似文献
9.
In an interferometer-based fluorescence microscope, a beam splitter is often used to combine two emission wavefronts interferometrically. There are two perpendicular paths along which the interference fringes can propagate and normally only one is used for imaging. However, the other path also contains useful information. Here we introduced a second camera to our interferometer-based three-dimensional structured-illumination microscope (I(5)S) to capture the fringes along the normally unused path, which are out of phase by π relative to the fringes along the other path. Based on this complementary phase relationship and the well-defined phase interrelationships among the I(5)S data components, we can deduce and then computationally eliminate the path length errors within the interferometer loop using the simultaneously recorded fringes along the two imaging paths. This self-correction capability can greatly relax the requirement for eliminating the path length differences before and maintaining that status during each imaging session, which are practically challenging tasks. Experimental data is shown to support the theory. 相似文献
10.
In this study, an innovative model has been developed for wind speed estimation through the Deep Learning method using hourly wind speed data from the measurement stations of the General Directorate of Meteorology in Van and Hakkari provinces in Turkey in conjunction with simultaneous satellite images from Eumetsat. Obtained satellite images were used during the introduction of the model, while wind speed data were used at the output stage. As a result of the findings, it was found that 85% accuracy performance could be achieved to provide sufficient insight for systems that are widely established worldwide. The model, developed as a result of the study, eliminates the need to install wind measuring stations for any region on earth within the satellite field in terms of determining wind potential. Since the field of view of the Meteosat 7 satellite covers the whole of Eastern Europe, it was determined that it could predict a high rate of up to 6 hours later by the method used in image analysis. The systems to be controlled with this method will be able to examine the weather events instantly at each point in the satellite field of view and make more accurate decisions. Also, companies will be able to perform a more detailed and rapid field scan compared to existing limited methods, and reduce initial investment costs and operating costs in terms of renewable energy resources investments. 相似文献