An adaptive joint source and channel coding scheme for H.264 video multicasting over wireless LAN

INTRODUCTION Video multicasting over wireless local area net- work (WLAN) (IEEE Standard 802.11, 1997) enables the distribution of live or pre-recorded programs to many receivers efficiently. An example application is to redistribute TV programs or location-specific in- formation in hot spots such as airport. Users can watch their favorite TV programs on mobile devices while browsing the Internet. For enterprise applica- tions, an example is multicasting video of a lecture or trainin…     

An error resilient scheme for H.264 video coding based on distortion estimated mode decision and nearest neighbor error concealment

Although H.264 video coding standard provides several error resilience tools, the damage caused by error propagation may still be tremendous. This work is aimed at developing a robust and standard-compliant error resilient coding scheme for H.264 and uses techniques of mode decision, data hiding, and error concealment to reduce the damage from error propagation. This paper proposes a system with two error resilience techniques that can improve the robustness of H.264 in noisy channels. The first technique is Nearest Neighbor motion compensated Error Concealment (NNEC) that chooses the nearest neighbors in the reference frames for error concealment. The second technique is Distortion Estimated Mode Decision (DEMD) that selects an optimal mode based on stochastically distorted frames. Observed simulation results showed that the rate-distortion performances of the proposed algorithms are better than those of the compared algorithms.     

花儿与少女——论《查泰莱夫人的情人》中的以花喻人

花儿作为生命、自然和爱的象征经常出现在D.H.Lawrence的作品中.Lawrence认为自然的生活才是真正的生活,而在现代社会里人们却离它越来越远.在《查泰莱夫人的情人》中,花儿几乎映现出所有人物的性格特点,有的强调精神至上,有的追逐物质享受,还有的热爱大自然……作者用花来比喻世间的完美女性--她们心灵纯洁,身体健康,生活自然,正像原野里盛开的朵朵鲜花.     

Catalytic properties of CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Ti0.3O2 in NO＋CO reaction

Using SnxTi1-xO2 as carriers, CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Ti0.3O2 catalysts with different loading amounts of copper oxide (CuO) were prepared by an impregnation method. The catalytic properties of CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Ti0.3O2 were examined using a microreactor-gas chromatography (GC) NO CO reaction system and the methods of BET (Brun- auer-Emmett-Teller), TG-DTA (themogravimetric and differential thermal analysis), X-ray diffraction (XRD) and H2-temperature programmed reduction (TPR). The results showed that NO conversions of Sn0.9Ti0.1O2 and Sn0.7Ti0.3O2 were 47.2% and 43.6% respectively, which increased to 95.3% and 90.9% at 6 wt% CuO loading. However, further increase in CuO loading caused a decrease in the catalytic activity. The nitrogen adsorption-desorption isotherm and pore-size distribution curve of Sn0.9Ti0.1O2 and Sn0.7Ti0.3O2 represented type IV of the BDDT (Brunauer, Deming, Deming and Teller) system and a typical mesoporous sample. There were two CuO diffraction peaks (2θ 35.5° and 38.7°), and the diffraction peak areas increased with increasing CuO loading. TPR analysis also detected three peaks (α, β and γ) from the CuO-loaded catalysts, suggesting that the α peak was the reduction of the highly dispersed copper oxide, the β peak was the reduction of the isolated copper oxide, and the γ peak was the reduction of crystal phase copper oxide. In addition, a fourth peak (δ) of the catalysts meant that the SnxTi1-xO2 mixed oxides could be reductive.     

AZ31B镁合金板材室温拉楔试验影响因素的研究

采用正交试验法研究板材变形程度、润滑条件、轴向加裁力大小和变形速度对AZ31B镁合金挤压板材室温拉楔性能的影响,结果表明:变形程度对拉楔试验顺利完成的影响最为显著,其次是润滑条件和轴向加载力大小,采用固体润滑剂的润滑效果优于油脂类润滑剂,且轴向加载力越大对拉楔试验成功越有利;而变形速度超过1 mm/min时,其影响效果不明显.在拉楔系数0.883,轴向加载力为拉楔力的1.759倍,使用固体肥皂作为润滑刑,取得了良好试验效果.     

深远的学术渊源,全新的语言观念——"''''三一''''语言学派"系列研究之一

由先行者王希杰的学术论著引发的、以王希杰为代表的学术群体所创立的"三一"语言学派已经具备作为一种流派所应该具有的必要而又充分的条件。这个学派吸纳了古今中外语言学理论和中国传统文化以及周边相关学科的学术思想,把王希杰化了的方光焘改造过了的索绪尔的语言观作为出发点,从而为其作为一种学术流派奠定了坚实的理论基础。     

黑藻属植物的核型分析

本文以根尖细胞为材料，观察了黑藻属Hydrilla植物的染色体核型。  它由两群染   色体组成：1—5 为长染色体，6—8 为短染色体。  染色体基数x=8。轮叶黑藻Hydrilla   verticillata(L. f.)Royle为二倍体；染色体数目为2n=2x=16；  雌雄之间既无染色体数   目的差别，也无异型染色体存在；核型公式为2n=2x=16＝6m+6Sm十4St。  罗氏轮叶   黑藻Hydrilla verticillata var．roxburgbii Casp系同源三倍体；  染色体数目为2n=3x=24；   核型公式为2n=3x=24=9m+9Sm+6St。