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991.
Hafiz Muhammad Noor ul Huda Khan Asghar Shuang Shi Dachuan Jiang Yi Tan Jalil Ur Rehman Zaheer Abbas Gilani Guangye An Xiaoliang Guo Penting Li 《SILICON》2018,10(5):1887-1891
Two 450 kg multicrystalline silicon ingots were obtained by mixing and melting high purity silicon and silicon from the edges and the bottom of the casted ingots together in a casting furnace. For one of the ingot, the silicon from casted ingots was refined in an electron beam melting furnace to remove oxygen. The oxygen content was reduced from 10 to less than 0.0517 ppmw when silicon was refined at 500 kW with removal efficiency up to 99.429% in the most areas. The life time of the ingot after oxygen removal was measured to be far better than another one, whereas in the central parts the value was almost 6.7 µs. The efficiencies of both solar cells were initially 17.55% but after 4 h decreased to 17.05% and 15.55%, respectively. The solar cell after oxygen removal shows a better performance in degradation. 相似文献
992.
Mojtaba Behzad Fallahpour Ali Jabbar Rashidi Abbas Sheikhi 《International Journal of Electronics》2018,105(5):771-783
Target recognition is one of the most important issues in the interpretation of the synthetic aperture radar (SAR) images. Modelling, analysis, and recognition of the effects of influential parameters in the SAR can provide a better understanding of the SAR imaging systems, and therefore facilitates the interpretation of the produced images. Influential parameters in SAR images can be divided into five general categories of radar, radar platform, channel, imaging region, and processing section, each of which has different physical, structural, hardware, and software sub-parameters with clear roles in the finally formed images. In this paper, for the first time, a behaviour library that includes the effects of polarisation, incidence angle, and shape of targets, as radar and imaging region sub-parameters, in the SAR images are extracted. This library shows that the created pattern for each of cylindrical, conical, and cubic shapes is unique, and due to their unique properties these types of shapes can be recognised in the SAR images. This capability is applied to data acquired with the Canadian RADARSAT1 satellite. 相似文献
993.
Wireless Personal Communications - Wireless Sensor Network has been widely used in a variety of applications such as; medical, agriculture, military, monitoring environment and so on. In healthcare... 相似文献
994.
Railway Engineering Science - Transportation demand management (TDM) covers strategies for reducing traffic congestion within the affected urban areas. Congestion pricing includes a branch of TDM... 相似文献
995.
Norliana Mohd Abbas Darius G. Solomon Md. Fuad Bahari 《International Journal of Machine Tools and Manufacture》2007,47(7-8):1214-1228
Electrical discharge machining (EDM) is one of the earliest non-traditional machining processes. EDM process is based on thermoelectric energy between the work piece and an electrode. A pulse discharge occurs in a small gap between the work piece and the electrode and removes the unwanted material from the parent metal through melting and vaporising. The electrode and the work piece must have electrical conductivity in order to generate the spark. There are various types of products which can be produced using EDM such as dies and moulds. Parts of aerospace, automotive industry and surgical components can be finished by EDM. This paper reviews the research trends in EDM on ultrasonic vibration, dry EDM machining, EDM with powder additives, EDM in water and modeling technique in predicting EDM performances. 相似文献
996.
Najafi Parviz Houshmand Viki Abbas Shahparasti Mahdi 《Electrical Engineering (Archiv fur Elektrotechnik)》2019,101(3):895-909
Electrical Engineering - The bipolar hybrid microgrid is a newly emerged structure which has gained increasing attention during the last decades. The heart of this structure is the interlinking... 相似文献
997.
The paper investigates the influence of reverse yielding on residual stresses induced by autofrettage. On the basis of reverse loading tests, a material model is developed and implemented into analytical procedures capable of treating the elasto-plastic deformation behaviour of thick-walled tubes during both loading and unloading phases. The results show that residual hoop stresses are drastically reduced near the tube bore as compared with residual stresses obtained from conventional isotropic hardening analysis. Pure kinematic hardening analysis is also shown to overestimate residual hoop stress induced by autofrettage. 相似文献
998.
Microwave absorption properties of double‐layer nanocomposites based on polypyrrole/natural rubber 下载免费PDF全文
Thin flexible double‐layer microwave absorbers have been fabricated based on polypyrrole (PP)/natural rubber (NR) nanocomposites and their reflection loss characteristics were studied in the range of 8–18 GHz. The PP‐NR matrix was prepared from PP and NR in the ratio of 15:85. The polymers used in this work not only serve as the matrix but also improve the microwave absorption properties. The first layer or impedance matching layer which is comprised of graphite, Fe3O4, and TiO2 nanoparticles in PP‐NR transmits the electromagnetic (EM) wave without reflection. The second layer which is made up of PP‐NR filled with Fe3O4 disperses the EM wave energy. The design of a double‐layer nanocomposite is a method to match the wave impedance, enhance wave absorption ability, and broaden the absorption frequencies. In order to achieve high absorption properties, the EM parameters such as permittivity, permeability, and thickness were controlled precisely according to quarter‐wave plate. The morphology, absorption properties, scattering parameters, thermal and wetting characteristics of double‐layer nanocomposites were investigated. The minimum reflection loss (RL) was ?32 dB at 12.1 GHz and the absorbing bandwidth in which the RL < ?10 dB was 9 GHz for optimum specimen with 2 mm thickness. For this specimen, the contact angle was equal to 118.7° with water as the liquid. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46565. 相似文献
999.
Nasim Movagharnegad Abbas Nikoo Zahra Shokri 《Polymer-Plastics Technology and Engineering》2018,57(18):1915-1922
Superparamagnetic Fe3O4 nanoparticles (MNPs) were functionalized by modified cellulose. The modified cellulose was synthesized through bromoacetylation of cellulose (BACell) followed by the substitution of sodium azide to form BACell-N3. The remaining methylene bromide groups on BACell-N3 was further reacted with the MNPs to form Fe3O4/Cell-N3. Then propargyl alcohol (PA) was immobilized on the azide-terminated Fe3O4 nanoparticles through copper (I)-catalyzed azide-alkyne cycloaddition (click reaction) to form Fe3O4/Cell/TAA nanoparticles. Doxorubicin (DOX) was loaded on prepared nanoparticles and release profiles of the DOX as a model drug from the Fe3O4/Cell/TAA nanoparticles and its loading capacity were determined by UV–Vis absorption at λmax 483?nm. 相似文献
1000.
The inherent nature of cognitive radio (CR) networks has brought new threats to wireless communications. Primary user emulation attack (PUEA) has been widely studied as a serious threat to cooperative spectrum sensing (CSS) in CR networks. In PUEA, a malicious user can obstruct CR users from accessing idle frequency bands by imitating licensed primary user (PU) signal characteristics. The present study introduces a new CSS scheme in the presence of a malicious PUEA based on multi-level hypothesis testing (MLHT). In the proposed method, generalizing from binary hypothesis testing to MLHT, we partition the decision space to four decision options and apply minimum Bayes cost criteria to determine the channel status. We also discuss practical limitation issues that need to be considered when applying the MLHT approach. Simulation results are provided to indicate the performance improvement of the proposed MLHT method against PUEA, compared with the conventional method. 相似文献