Sequential packing algorithm for channel assignment under cochanneland adjacent-channel interference constraint

Generally, the channel-assignment problem (CAP) for mobile cellular systems is solved by graph-coloring algorithms. These algorithms, though sometimes can yield an optimal solution, do not supply any information on whether an optimal solution has been found or bow far away it is from the optimum. In view of these undesirable features, two relevant results are presented. First, a lower bound for the minimum number of channels required to satisfy a given call-traffic demand is derived. This lower bound is tighter than the existing ones under certain conditions and can be used as a supplement for other approximate algorithms. Second, we propose an efficient heuristic algorithm to solve this problem. Although the CAP is nondeterministic polynomial (NP) complete in general, our algorithm provides an optimal solution for a special class of network topologies. For the general case, promising results are obtained, and numerical examples show that our algorithm has a better performance than many existing algorithms     

Word长文档框架结构的编排技巧

本文介绍了Word长文档框架结构的编排技巧。     

CO2气层录井识别影响因素分析与解释评价

松辽盆地南部深层天然气储集层富含CO2,随着勘探的深入进行,CO2气层的录井识别与评价难题已突显,主要表现为异常发现和分层困难,无法定量评价。从CO2特殊的物理化学性质分析入手,通过实验分析,确认了CO2气层录井出现分层和评价困难的主要原因是CO2在水中的高溶解度、高扩散性和溶于水后产生的弱酸性。进一步通过研究CO2与甲烷录井密切的伴生关系以及甲烷气的录井显示灵敏性,结合钻时、CO2与甲烷的相对含量高低等录井参数,在现有技术条件下,初步建立了CO2气层的录井识别评价方法。     

Forecast and evaluation of hot dry rock geothermal resource in China

Utilizing information from plate tectonics characteristics, volcanic activities, and geothermal anomaly, this paper identifies areas where hot dry rock (HDR) may exist as potential geothermal resource in China. Further investigations are also carried out in the paper based on results from regional tectonics, volcanic geology and lithology, as well as data from geothermal displays, geochemistry, geophysics, and shallow borehole temperature measurements. The study reveals several promising areas of HDR geothermal resource in China, including Tengchong of Yunnan province, Qiongbei of Hainan province, Changbaishan of Jilin province, Wudalianchi of Heilongjiang province, and the Southern Tibet area. A 3D static heat conduction model was developed to study the underground temperature gradient characteristics of the Rehai geothermal field in Tengchong and the Yangbajing geothermal field in Tibet. The model adopted is a geological block 10 km deep from the ground surface and 50 km wide in each of the horizontal directions (2500 km² area). The numerical simulation results in evaluations on the quantities of the HDR geothermal resource in Rehai and Yangbajing geothermal fields. The paper shows that there is abundant HDR geothermal resource with large exploitation value in China. If developed with a power capacity of 1×10⁸ kW, the Rehai and Yangbajing fields along would be able to generate electricity for 1560 years.     

Effect of structure on porous gas-diffusion electrodes for phosphoric acid fuel cells

This investigation is concerned with the variation of structure in the catalyst layer for porous gas-diffusion electrodes. The pore-size distribution and the total pore volume of the electrode are measured by a mercury penetration method. A model that accounts for this incomplete wetting electrode is solved by an orthogonal collocation method and matched with experimental observations. The numerical solution indicates that the effectiveness factor drops noticeably under high current density when the agglomerate radius is greater than 40 μm. When the agglomerate radius is smaller than 1.2 μm, however, the effect of ionic transport becomes important. The maximum reaction rate occurs at carbon-paper/ catalyst-layer interface when the effective conductivity of the electrolyte is larger than that of the solid phase. If the effective conductivity of the electrolyte is smaller, then the maximum reaction rate occurs at the electrode/electrolyte interface.     

A Novel SAO-based Filtering Technique for Reduction in Temporal Flickering Artifacts in H.265/HEVC

This paper presents a novel filtering technique based on sample adaptive offset (SAO) in H.265/high-efficiency video coding (HEVC) for reduction in the temporal flickering artifacts and improving the coding performance. SAO is a newly introduced technique for in-loop filtering in H.265/HEVC, which derives the offsets independently for each frame in the spatial domain without considering temporal frame correlation. As a result, the temporal distortion artifacts which will have a negative effect on the subjective quality, such as flickering artifacts, cannot be effectively addressed. In this paper, the rate-distortion optimization of the newly developed SAO method, referred to as Inter-SAO, is performed on the residual samples between adjacent frames. Inter-SAO and SAO in the reference software of H.265/HEVC (i.e., the test model HM) are then combined to form the novel in-loop filter-based method, denoted as 3D-SAO filtering method, where both spatial information and temporal information are effectively utilized to reduce the overall distortion in reconstructed videos. Compared with the SAO in HM, 3D-SAO has demonstrated its advanced performance for flickering artifacts suppression. Furthermore, 3D-SAO improves the coding efficiency compared with the SAO in HM with a performance gain of up to 0.91 dB in \(\Delta PSNR\), 1.74 dB in \(\Delta PSPNR\) and 7.33 % in BD-rate reduction.     

基于提升小波的图像水印算法

文中提出了一种基于能量特性分块的小波域图像水印算法，采用JPEG2000静态图像压缩标准的变换核——Daubechies9／7双正交小波进行小波变换，利用其三段低频小波系数之间的能量关系，将随机置乱的水印嵌入到图像中，并自适应调整嵌入强度因子。实验证明，该算法具有良好的不可见性和鲁棒性。