Optimal resource allocation for wireless video over CDMA networks

We present a multiple-channel video transmission scheme in wireless CDMA networks over multipath fading channels. We map an embedded video bitstream, which is encoded into multiple independently decodable layers by 3D-ESCOT video coding technique, to multiple CDMA channels. One video source layer is transmitted over one CDMA channel. Each video source layer is protected by a product channel code structure. A product channel code is obtained by the combination of a row code based on rate compatible punctured convolutional code (RCPC) with cyclic redundancy check (CRC) error detection and a source-channel column code, i.e., systematic rate-compatible Reed-Solomon (RS) style erasure code. For a given budget on the available bandwidth and total transmit power, the transmitter determines the optimal power allocations and the optimal transmission rates among multiple CDMA channels, as well as the optimal product channel code rate allocation, i.e., the optimal unequal Reed-Solomon code source/parity rate allocations and the optimal RCPC rate protection for each channel. In formulating such an optimization problem, we make use of results on the large-system CDMA performance for various multiuser receivers in multipath fading channels. The channel is modeled as the concatenation of wireless BER channel and a wireline packet erasure channel with a fixed packet loss probability. By solving the optimization problem, we obtain the optimal power level allocation and the optimal transmission rate allocation over multiple CDMA channels. For each CDMA channel, we also employ a fast joint source-channel coding algorithm to obtain the optimal product channel code structure. Simulation results show that the proposed framework allows the video quality to degrade gracefully as the fading worsens or the bandwidth decreases, and it offers improved video quality at the receiver.     

Al_(10)Zn_(2.9)Mg_(1.7)Cu超高强铝合金的喷射成形制备研究

采用喷射成形技术制备了Al1 0 Zn2 .9Mg1 .7Cu高强高韧铝合金沉积坯件 ,研究了喷射成形制备过程中各工艺参数对沉积坯件的成形性、显微组织、致密度的影响 ,确定了适当的工艺参数 ,研究了沉积坯件的热挤压及热处理工艺 ,对材料的组织进行了分析并对不同状态的材料性能进行了比较。研究结果表明 :当喷射成形工艺参数合理时 ,沉积坯件具有良好的成形性与致密度 ,在随后的热挤压过程中 ,通过较低的挤压比即可使材料达到全致密 ;通过对合金进行适当的热处理 ,材料的极限抗拉强度达到 810MPa ,同时延伸率保持在 8%～ 11% ,该材料是一种理想的轻质高强结构材料。     

GM300电台的调试原理及方法

GM300电台是一种性能优良的电台，目前在我国的地震勘探领域广泛应用。与其它类型的电台相比，GM300电台的调试方法完全不同。掌握其调试原理及方法是对该类电台进行正确维护的基础。本文从分析GM300电台调试原理入手，总结了该电台的调试方法。     

水轮机过流部件磨蚀问题的研究与防护

针对我国高含沙水流中运行的水轮机组的过流部件的磨蚀这个长期存在的疑难问题，开展研究工作，在分析水轮机过流部件泥沙磨损、空化破坏各自的磨损机理、特点、影响因素、预测模型等的基础上，总结出水轮机过流部件的磨蚀主要是泥沙磨损、空化破坏及它们的联合作用，提出水轮机过流部件磨蚀的主要防护措施，为最终解决水轮机过流部件磨蚀问题提供了理论依据。图6幅，表1个。     

Quality assurance

BACKGROUND: The treatment of pediatric empyemas remains controversial. While thoracentesis and tube thoracostomy appear adequate for relatively benign organisms, virulent bacteria cause thick fibrinous pleural peels entrapping the lung. Open thoracotomies have been effectively used for decortication but are painful. METHODS: We report the use of minimally invasive thoracoscopic decortication in 12 patients (mean age 5 years). All failed conventional management with persistent fever, increasing oxygen requirement, recurrent effusion, and pleural consolidation; 5- and 10-mm trocars were used and complete decortication was accomplished. RESULTS: Ten of 12 patients were afebrile by 72 h and discharged 4-12 days after surgery. Eleven of 12 patients had clear chest x-rays by 1 month. CONCLUSION: Thoracoscopic decortication is a safe and effective means of treating pediatric empyemas.     

模糊环境的表示及机器人轨迹规划

本文利用模糊集理论，提出一种非确定环境的描述方法，并且针对机器人在该类环境中的避障轨迹规划，建立了相应的决策函数和规划策略，最后，给出在ＰＣ－３８６计算机上的仿真试验结果。     

ATP-Dependent inhibition of Ca2+-activated K+ channels in vascular smooth muscle cells by neuropeptide Y

Neuropeptide Y(NPY) inhibits Ca2+-activated K+ channels reversibly in vascular smooth muscle cells from the rat tail artery. NPY (200 microM) had no effect in the absence of intracellular adenosine 5'-triphosphate (ATP) and when the metabolic poison cyanide-M-chlorophenyl hydrozone (10 microM) was included in the intracellular pipette solution. NPY was also not effective when ATP was substituted by the non-hydrolysable ATP analogue adenosine 5'-[beta gamma-methylene]-triphosphate (AMP-PCP). NPY inhibited Ca2+-activated K+ channel activity when ATP was replaced by adenosine 5'-O-(3-thiotriphosphate) (ATP [gamma-S]) and the inhibition was not readily reversed upon washing. Protein kinase inhibitor (1 microM), a specific inhibitor of adenosine 3', 5'-cyclic monophosphate-dependent protein kinase, had no significant effect on the inhibitory action of NPY. The effect of NPY on single-channel activity was inhibited by the tyrosine kinase inhibitor genistein (10 microM) but not by daidzein, an inactive analogue of genistein. These observations suggest that the inhibition by NPY of Ca2+-activated K+ channels is mediated by ATP-dependent phosphorylation. The inhibitory effect of NPY was antagonized by the tyrosine kinase inhibitor genistein.     

小型水电站联网改造应注意的几个问题

针对铜鼓县小水电站联网时存在的问题及其不利影响进行了分析，井提出了改进途径，指出小水电站的联网改造应立足安全，争取效益。     

PET／PC共混物的辐射效应研究

研究了经溶液共混制备的聚对苯二甲酸乙二醇酯／聚碳酸酯（ＰＥＴ／ＰＣ）共混物的辐射效应。结果表明：ＰＥＴ／ＰＣ共混物在辐照过程中未发生酯交换反应和交联反应，但有降解反应发生。在研究的剂量范围内，辐照对ＰＥＴ／ＰＣ共混物中ＰＥＴ和ＰＣ的晶体形态影响不明显。     

珠江口盆地开平凹陷油气聚集条件分析

珠江口盆地自新生代以来,曾先后受到不同方向张应力的作用,造成了不同时期构造体系的交叉叠合.中中新世以来构造运动强烈,并具有东强西弱的特点,对油气的运移与聚集产生了重要影响.开平凹陷的剧烈断裂和断陷活动始于始新世,并在同期沉积了巨厚的文昌组.晚渐新世以后,由于断裂活动非常微弱,在成熟的烃源岩与其上地层之间缺乏有效的油源断层,因而自生自储、近距离运移可能是开平凹陷油气聚集的基本特征.在凹陷内部,因重力滑动和欠压实泥岩共同作用所形成的KPll-1构造带可能是该区最具有油气远景的地区.