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971.
972.
973.
For the capillary mats using wet construction, a winter experiment designed to investigate the heat transfer performance was described, and the heat transfer performance analysis which contains the comparisons between different pipe space and different thickness of cement mortar surface was carried out. As a result, compared with that of the traditional radiant heating pipes, the capillary mats of wet construction require supply water with lower temperature, and it shows good heat transfer performance and system energy efficiency as well. According to the demand of indoor heat dissipation and human comfort as well as the coupling relationship between the temperature of supply water and surface construction thickness, it is suggested that the proper construction method should be comprehensively considered in practical applications. 相似文献
974.
Two kinds of stearic acid (SA)/ attapulgite (ATTP) composite phase change materials (PCMs) were prepared for the latent heat thermal energy storage (LHTES) in buildings or other area by the methods of fusion and immersion, using SA as PCMs and ATTP supplied by Linze of Gansu province as supporting material. The structure, thermal properties, thermal reliability and heat storage or release performance of the composite PCMs were determined by scanning electron microscope (SEM), fourier transformation infrared (FTIR), differential scanning calorimetry (DSC) and thermal cycling test analysis technique. The results indicate that the preparation method has no effect on the structure and morphologies of the composites. Two kinds of composites have same structure due to the SA adsorbed in the surface of ATTP by physical reaction. The results also show that two form-stable composites PCMs have the optimal effect for preventing SA leak from the composite emerges when the maximum load proportion of SA in the composites were 38.64wt% and 29.13wt%. The latent heats and phase change temperature were measured as 68.71 J/g and 57.3℃ for the composite which was prepared by fusion method and 51.79 J/g and 55.2℃ for the composite fabricated by immersion method, respectively. The results of DSC, FTIR and thermal cycling test are all showing that two kinds of composites have good heat storage property but the composite prepared by fusion method has a better thermal and chemical stability. 相似文献
975.
The time-frequency coupling relation between useful non-stationary components and noises bring great difficulties to the realization of de-noising for non-stationary signals,which can not be solved by classic de-noising method in time or frequency domain. The principles of short time Fourier transform(STFT),Wigner-Ville transform,Chirplet adaptive decomposition are analyzed,and then a novel de-noising method for non-stationary based on joint time-frequency distribution is proposed. In this method,the analyzed signal WVD is seen as the combination of auto-WVD and cross-term WVD. Firstly,STFT energy spectrum of the analyzed signal is used as template to cross-correlate with its corresponding WVD in order to obtain the satisfactory time-frequency distribution with high time-frequency resolution and without cross-term interferences. Secondly,the useful components are decomposed as Chirplet function using the two-dimension least square fitting method,and then are extracted out to reconstruct for noise suppression. Finally,the computer simulation results verify the effectiveness of this proposed method. Its application in gearbox fault diagnosis indicates that with the method the extracted cycle of the gearbox vibration impulses has a good consistency with the corresponding fault frequency. 相似文献
976.
Asymmetrical grid faults occur more frequently and have more adverse effects on the doubly fed induction generator (DFIG) than symmetrical grid faults in the transmission system. The transient response of DFIG under asymmetrical grid faults is analyzed firstly. Meanwhile, operation behaviors of several low voltage ride-through (LVRT) techniques under severe asymmetrical grid faults are given by simulation with the Matlab/Simulink software. Then the characteristics of these LVRT techniques are further researched and analyzed based on the simulation results. Finally, the economies of these LVRT techniques are discussed. The conclusion lays a certain foundation for engineering development of these LVRT techniques. 相似文献
977.
基因型及外源因子对小麦花药培养一步成苗的影响 总被引:7,自引:0,他引:7
研究了不同基因型及几种外源因子在小麦花药培养一步成苗中的效应。结果表明 ,花药培养一步成苗的愈伤组织诱导率、绿苗分化率、白苗分化率及绿苗产量存在基因型间的差异。高蔗糖浓度有利于获得高频率的花药愈伤组织 ,但同时又提高了花药培养中白化苗频率。动力精 (KT)对花药愈伤组织诱导率影响的差异不大 ,但对绿苗分化率、绿苗产量及绿苗 /白苗 (G/ W)均有显著影响。在试验浓度范围内 ,随 KT浓度的增大 ,绿苗产量提高 ,绿苗分化率明显增加 ,而白苗分化率下降 ,因而 G/ W值明显增大。说明 KT主要是通过提高绿苗分化率和降低白苗分化率 ,增大 G/ W而提高花培一步成苗效率的。在与 KT的配合使用中 ,2 ,4 - D比 NAA更有利于提高小麦花药培养中的愈伤组织诱导率和苗分化频率 相似文献
978.
小分子植物病毒抑制物质研究进展 总被引:2,自引:0,他引:2
论述了小分子病毒抑制物的结构及对病毒的抑制机理 ,讨论了植物病毒抑制剂研究中存在的问题及研究前景 相似文献
979.
废聚苯乙烯泡沫塑料(PSF)制备胶粘剂中溶剂的选择 总被引:3,自引:0,他引:3
研究了利用废聚苯乙烯制备胶粘剂中溶剂的选择及溶剂比例的确定。结果表明:溶解聚苯乙烯的理想溶剂为二甲苯、乙酸乙酯和正丁醇的混合溶剂。当二甲苯、乙酸乙酯和正丁醇的比例为2∶3∶3时,制得胶粘剂的性能较好。 相似文献
980.