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工业水系统中的天然硬水的使用会导致严重的设备表面结垢和腐蚀,并且造成严重的技术和经济问题。如今,多种抑制剂已经被用于工业水系统(如冷却水系统),目的是解决这些问题。 相似文献
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Error rate performance of coded free-space optical links over strong turbulence channels 总被引:1,自引:0,他引:1
Error control coding can be used over free-space optical (FSO) links to mitigate turbulence-induced fading. We present error rate performance bounds for coded FSO communication systems operating over atmospheric turbulence channels, which are modeled as a correlated K distribution under strong turbulence conditions. We derive an upper bound on the pairwise error probability (PEP) and then apply the union-bound technique in conjunction with the derived PEP to obtain upper bounds on the bit error rate. Simulation results are further demonstrated to verify the analytical results. 相似文献
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Broadband communications for indoor power-line networks with impulsive noise using orthogonal frequency division multiplexing (OFDM) is considered. From earlier investigations, it is known that this channel suffers from multipath fading and frequency selectivity along with man-made impulsive bursty noise. Nevertheless, the calculated channel capacity limit promises very high data rates over this channel. Enhancement techniques, such as coding can help an OFDM system to tackle impulsive noise burst. In this paper, the bit error rate (BER) performance of the OFDM system under impulsive noise and frequency fading is theoretically analyzed and closed form expression for the performance is derived. Two different impulsive noise environment models are studied and it is confirmed that both models represent the same environment. Furthermore, a theoretical upper bound on the performance of coded OFDM system is obtained, given perfect interleaving. The effect of the interleaver length on coding performance is also studied. Simulations show that the upper bound is quite tight for the case of employing a longer interleaver. The effect of interleaver size on the system performance is studied, as well. 相似文献
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A. H. Navidpour Y. Kalantari M. Salehi H. R. Salimijazi M. Amirnasr M. Rismanchian M. Azarpour Siahkali 《Journal of Thermal Spray Technology》2017,26(4):717-727
Fabrication of semiconductor coatings with photocatalytic action for photodegradation of organic pollutants is highly desirable. In this research, pure zinc oxide, which is well known for its promising photocatalytic activity, was deposited on stainless-steel plates by plasma spraying. The phase composition and microstructure of the deposited films were studied by x-ray diffraction analysis and scanning electron microscopy, respectively. Despite the low-energy conditions of the plasma spraying process, the zinc oxide coatings showed good mechanical integrity on the substrate. Their photocatalytic activity was evaluated using aqueous solution of methylene blue at concentration of 5 mg L?1. The results showed the potential of the plasma spraying technique to deposit zinc oxide coatings with photocatalytic action under ultraviolet illumination. Ultraviolet–visible (UV–Vis) diffuse reflectance spectroscopy confirmed that the plasma spraying method could deposit zinc oxide films with higher photoabsorption ability relative to the initial powder. 相似文献
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Navidpour S.M. Uysal M. Kavehrad M. 《Wireless Communications, IEEE Transactions on》2007,6(8):2813-2819
Free space optical (FSO) communications is a cost-effective and high bandwidth access technique, which has been receiving growing attention with recent commercialization successes. A major impairment in FSO links is the turbulence- induced fading which severely degrades the link performance. To mitigate turbulence-induced fading and, therefore, to improve the error rate performance, spatial diversity can be used over FSO links which involves the deployment of multiple laser transmitters/receivers. In this paper, we investigate the bit error rate (BER) performance of FSO links with spatial diversity over log- normal atmospheric turbulence fading channels, assuming both independent and correlated channels among transmitter/receiver apertures. Our analytical derivations build upon an approximation to the sum of correlated log-normal random variables. The derived BER expressions quantify the effect of spatial diversity and possible spatial correlations in a log-normal channel. 相似文献
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