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991.
Rheological behavior of dispersed two-phase polymer melts has been investigated by means of a capillary rheometer. The two-phase systems chosen for study were blends of two polymers: high-density polyethylene and polystyrene, which are incompatible in the molten state. In order to investigate the state of dispersion, photographs were taken of the microstructure of extrudate samples, showing that the polystyrene forms long fibers or droplets as a discrete phase dispersed in the polyethylene which forms a continuous phase. Measurements were made of the axial pressure distributions of the two-phase molten polymers flowing through circular tubes, which permit one, according to the theory advanced by Han, to determine viscous and elastic properties of the melts. Also measured was melt die swell ratio. It has been found from the two independent experimental techniques that there exist a maximum and/or minimum elastic property at a certain blending ratio, and that the elastic property decreases first with L/D ratio of a capillary and then levels off. 相似文献
992.
993.
Zhi-Ping Jiang Wei Xi Xiangyang Li Shaojie Tang Ji-Zhong Zhao Jin-Song Han Kun Zhao Zhi Wang Bo Xiao 《计算机科学技术学报》2014,29(4):589-604
Numerous indoor localization techniques have been proposed recently to meet the intensive demand for location-based service (LBS). Among them, the most popular solutions are the Wi-Fi fingerprint-based approaches. The core challenge is to lower the cost of fingerprint site-survey. One of the trends is to collect the piecewise data from clients and establish the radio map in crowdsourcing manner. However the low participation rate blocks the practical use. In this work, we propose a passive crowdsourcing channel state information (CSI) based indoor localization scheme, C2IL. Despite a crowdsourcing based approach, our scheme is totally transparent to the client and the only requirement is to connect to our 802.11n access points (APs). C2IL is built upon an innovative method to accurately estimate the moving speed solely based on 802.11n CSI. Knowing the walking speed of a client and its surrounding APs, a graph matching algorithm is employed to extract the received signal strength (RSS) fingerprints and establish the fingerprint map. For localization phase, we design a trajectory clustering based localization algorithm to provide precise real-time indoor localization and tracking. We develop and deploy a practical working system of C2IL in a large office environment. Extensive evaluations indicate that the error of speed estimation is within 3%, and the localization error is within 2 m at 80% time in a very complex indoor environment. 相似文献
994.
枸杞黑果病是枸杞产区的主要病害.发病后造成黑花、黑蕾和黑果,使枸杞产量降低,品质变劣。为探明四种杀菌剂对枸杞黑果病的防治效果及最佳剂量,2003年对下述四种杀菌剂进行了田间药效对比试验,调查防效结果如下:20%三苯基醋酸锡WP450~281g/hm^2(以有效成分计,下同),20%氟硅唑EC21.08g/hm^21.5%噻霉酮EW16、88~21.08g/hm^2、40%氟硅唑EC450g/hm^2和70%甲基托布津WP787.5g/hm^2对枸杞黑果病防效均在88.25%以上。经LSD检验各处理间防效无显著差异。 相似文献
995.
Yu. N. Shebeko A. Ya. Korol'chenko V. G. Shamonin S. G. Tsarichenko 《Combustion, Explosion, and Shock Waves》1991,27(2):173-175
Through numerical simulation of flame propagation through a methane- and hydrogen-air mixture, with consideration given to the transfer and chemical reactions, we have investigated the relationship between the kinetics of trimolecular reactions and the baric index of the normal burning velocity. It has been demonstrated that the lower the constants of the trimolecular reaction rates, the higher the magnitude of the baric index. In the case of methane the baric index, although it grows, it nevertheless remains negative, while in the case of hydrogen this index changes sign.Balashikha. Translated from Fizika Goreniya i Vzryva, No. 2, pp. 46–49, March–April, 1991. 相似文献
996.
制备了含10vol%,20vol%及30vol%SiC晶须的Si_3N_4基复合材料,对其室温及高温机械强度的测试研究表明,SiC晶须对基体的高温机械性能有明显的增强作用。含20vol%SiC晶须的复合材料1200℃下强度达780MPa,比基体材料提高50%。通过SEM和TEM研究,讨论了SiC晶须增强的原因。 相似文献
997.
998.
Aniline-modified epoxy resin which contains tertiary amine in the middle of the polymer chain was synthesized by the reaction of aniline and epoxy resin. The resulting aniline-modified epoxy resin and two commercial epoxy resins with different epoxy equivalent weights were reacted with 2-ethylhexanol-blocked toluene diisocyanate (2-EH-blocked TDI) to obtain thermally crosslinkable epoxy resins. These epoxy resins were subsequently reacted with various secondary amines and partially neutralized with acetic acid to give thermally crosslinkable cationic resins. The resulting cationic resins were dissolved in suitable solvents and mixed with deionized water to form emulsions. The crosslinking properties, emulsion, and electrodeposition properties of these resins were studied in some detail. The electro-deposition yields of the emulsions prepared from aniline-modified epoxy resins were higher than those of other emulsions. The crosslinked films prepared from aniline-modified epoxy resins were also glossier than those prepared from commercial epoxy resins. High deposition yield and high glossiness were the characteristic properties of the aniline-modified epoxy resins. Thermal properties were not affected by aniline-modified epoxy resins. 相似文献
999.
Although leather has a number of desirable properties such as thermal stability and fire retardancey, in addition to high toughness, it has a few drawbacks such as weight, high water absorption, poor soil and rot resistance, and nonuniformity. If these defects are overcome, leather's usefulness would be further enhanced and its competitive position with respect to synthetics would increase. This study reports the physical and mechanical properties of buffalo leather after chemical graft copolymerization with ethyl acrylate, butyl acrylate, and 2‐ethyl hexyl acrylate using benzoyl peroxide as an initiator. The optimum conditions for grafting (e.g., monomer and initiator concentrations, temperature and time of grafting, and solvent leather ratio) were extensively investigated. The study achieved outstanding properties for buffalo leather in reduction of water uptake after grafting, especially on using 2‐ethyl hexyl acrylate and butyl acrylate monomers. FT‐IR and solid 13C‐NMR for leather before and after grafting confirmed the grafting process.© 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1478–1483, 2003 相似文献
1000.
Based on the theory of approximate similarity of soil-ejection underground explosions, a technique for laboratory modeling of this phenomenon by microexplosions has been developed. This paper describes the experimental setup and reports some results obtained from experiments on selection of a soil simulator and from experiments on elucidation of the atmospheric-pressure role with varied scales of the phenomenon. The results are interpreted by comparing them with full-scale explosions and theoretical data.Russian Research Institute of Technical Physics, 454070, Snezhinsk. Translated from Fizika Goreniya i Vzryva, Vol. 31, No. 2, pp. 102–109, March–April, 1995. 相似文献