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61.
An important issue for video transmission over IP networks is preservation of perceived video quality despite packet loss. Packet loss can be detrimental to compressed video. However, reducing packet loss to a very low level is difficult with current loss control techniques. Furthermore, even a very low objective loss probability can still seriously distort perceived video quality. This paper presents two buffer management schemes using video characteristics. They increase maximum loss tolerance for a desired level of video quality, providing better quality at equal loss ratios, when compared to a conventional buffer management scheme. Meanwhile, service fairness and network efficiency are also improved. 相似文献
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针对改善催化裂化反应微环境研制开发的DCA - 112催化裂化抑焦剂 ,具有抑制生焦、改善产品分布、应用流程简单、加注方便等特点 ,经中石化长炼分公司 1Mt/a重油催化装置工业应用表明 ,在相近的工艺条件下 ,掺渣比提高 4 13个质量百分点 ,总液收提高 1 0 2个质量百分点。 相似文献
64.
文章从如何提高对工程量清单编制工作重要性的认识入手,分析了实现计价理念、计价侧重点和造价控制观念转变的必要性,重点阐述了提高工程量清单编制质量应给予足够重视的几个关键环节。 相似文献
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A new type of polysiloxane modified polyurethane–acrylic hybrid emulsion was synthesized by solvent-free method and the polysiloxane was introduced into the soft segment of polyurethane chains using dihydroxybutyl-terminated polydimethylsiloxane (PDMS). The formed film from the hybrid emulsion could provide obviously higher water-resistance property. The preparation technologies such as the content of carboxy group and acrylic monomer, the rate and the time of emulsification were discussed systematically. The chain structure and the particle size were confirmed by the analysis of Fourier transform infrared spectroscopy and transmission electron microscopy, respectively. The effect of PDMS content on the water resistance and the mechanical property were investigated by absorbed water ratio, water contact angle and dynamic mechanical measurement. 相似文献
68.
白洁 《信息安全与通信保密》2006,(10):37
石油业在信息化系统建设方面一直着眼于提高效率,希望无缝满足当前和未来的业务拓展需要。其业务不断拓展和多元化,要求信息系统整体提供更高的访问,必须为勘探和生产活动的顺利进行提供全面的保障。无论从地理特性还是业务拓展的需求上,石油行业都需要高效的应用访问能力,避免 相似文献
69.
Nibedita Mitra Kalyani Vijayan B. N. Pramila Bai S. K. Biswas 《Journal of the American Ceramic Society》1993,76(2):533-535
Cutting of Y2 O3 -doped TZP rods by a low-speed diamond saw introduces an unidentified, metastable phase X (x -ZrO2 ) coexisting with the tetragonal ( t -ZrO2 ) and the monoclinic ( m -ZrO2 ) phases initially present in the sample. Further mechanical deformation of the cut surface by indentation or polishing sustains the x -ZrO2 . Chemical etching removes the x -ZrO2 and increases the m -ZrO2 content. 相似文献
70.
Traditional parenteral nutrition (PN) and chemotherapy may lead to changes mucosal morphology and gut barrier function. To investigate the effects of alanyl-glutamine on intestinal mucosal morphology and gut barrier function in PN-fed rats challenged with 5-FU male Wistar rats were central catheterized and randomily divided into two groups: PN group (n = 10) that received traditional parenteral nutrition solution only, and Ala-Gln group (n = 10) that received glutamine dipeptide enriched nutritional solution (3% Ala-Gln). The rats were maintained on their respective diets for 7 days. 5-FU (75 mg/kg) was injected intraperitoneally at 8 am on day 4. All rats were gavaged with lactulose (100 mg) and mannitol (50 mg) in 2ml before and three days after administration of 5-FU. Ala-Gln group maintained serum glutamine concentration, intestinal mucosal morphology. While bacterial translocation rates in ala-Gln group was 30%, in PN group was 90% (P < 0.05). Similar intestinal permeability was observed on day 3 in both groups. The control group had a significantly increased intestinal permeability on day 7 (P < 0.05), while Ala-Gln group maintained the intestinal permeability. It was suggested that alanyl-glutamine maintained intestinal morphology and gut barrier function in PN-fed rats challenged with 5-FU. 相似文献