全球移动增值业务发展现状

移动增值业务在全球的发展速度依然很快,非话音收入占电信总收入的比重越来越大.在移动增值业务的发展上,日本遥遥领先,韩国紧随其后.在中国,虽然短信业务收入开始下降,但无线应用协议(WAP)、交互式语音回应(lVR)等业务收入快速攀升,从而保证了移动增值业务在中国的发展速度.由于中国信息产业部整顿收费混乱的移动增值业务市场,使服务提供商/内容提供商(SP/CP)的暴利时代成为过去,增值业务市场进入精耕细作期.随着用户对移动增值业务新的需求的不断增长,整首音乐下载、移动E-mail以及手机电视等业务将成为未来全球最有前途的移动增值业务.     

富氧燃烧技术在梭式窑中的应用

研究了富氧燃烧技术对梭式窑烧成的影响.研究结果表明,随着氧浓度从21%-30%的逐渐增加,CO总浓度和NO总浓度都先明显下降,后缓慢上升;节能效果在初始段较为明显,而后效果不明显;而实际烟气量与氧浓度成反比,与过剩空气系数成正比.     

主跨348m+348m三塔单索面PC梁斜拉桥

宜昌市夷陵长江大桥采用三塔斜拉桥，总体布置为(128．08 348 348 120．35)m。介绍了该桥的合理性及结构特点。     

装配式基坑支护结构在广州地区的应用

装配式基坑支护结构是将基坑支护的围护结构部分在工厂预制成型,再在现场与撑或锚装配组成的支护结构。工程实践表明,此项技术可有效节省工程投资、缩短工期。     

介孔氧化铁对正辛醇乙氧基化反应的催化性能

以十二烷基磺酸钠为模板剂、乙二胺为碱性介质,将水热法合成的氧化铁/十二烷基磺酸钠复合中孔材料在550℃、空气气氛中煅烧10h,除去模板剂,得到介孔氧化铁。通过X射线衍射、氮气吸附-脱附方法对介孔氧化铁的晶体结构和表面物性进行表征。表征结果显示,煅烧后的介孔氧化铁具有典型的六方介孔的结构特征,平均孔径为5.4nm。将介孔氧化铁用于催化正辛醇乙氧基化反应,研究结果表明,升高反应温度和初始压力、增加催化剂用量,可加快环氧乙烷的反应速率,同时产物的相对分子质量分布较窄。当平均聚合度为6.5时,正辛醇聚氧乙烯醚相对分子质量分布的选择性系数达到21.1。     

Effect of process parameters on impact strength of Al-7% Si alloy castings produced by VAEPC process

The castings produced by the evaporative pattern casting (EPC) process have blow holes. The blow holes in EPC castings are because of the non-escape of the gas produced as a result of burning of polystyrene pattern in the sand mold. To overcome the problem of blow holes, the EPC process is combined with the vacuum (V)- process. The vacuum applied to EPC mold draws the decomposed gases and improves the casting quality produced by the EPC process. The developed hybrid process has been termed as the vacuum assisted evaporative pattern casting (VAEPC) process. The objective of this paper to investigates the effect of process parameters, i.e, degree of vacuum, pouring temperature, grainfineness number, amplitude of vibration and time of vibration on the impact strength of Al-7% Si alloy castings in VAEPC process. In order to evaluate the effect of selected process parameters, the response surface methodology (RSM) is used to formulate a mathematical model which correlates the independent process parameters with the desired impact strength. The central composite rotatable design has been used to conduct the experiments. The results indicate that the impact strength decreases with increases in the grainfineness number and pouring temperature. Whereas, it has an inverse relationship with amplitude of vibration, time of vibration and degree of vacuum. The best value of impact strength (2.34 N/mm²) has been obtained at 400 mm Hg degree of vacuum imposed, 650°C as pouring temperature, 60 as sand grainfineness number, 460 μm as amplitude of vibration, and 70 s as time of vibration.     

裂齿矩形翅片板翅式换热器优化设计的分析

对裂齿矩形翅片板翅式换热器中的裂齿矩形翅片的传热效率作了分析,并以单位质量材耗的换热能力最大为目标函数,分析研究了在不同雷诺数(Re)的操作条件下裂齿矩形翅片间角度、翅片厚、长度、宽度及极厚之间的关系。结果表明:在气体换热的场合下,当Re在某一范围时翅片可有效地起到强化传热的作用。当板厚为5mm,翅片厚为3mm,翅片间夹角为45°～70°,Re为2×10~3～8×10~3,最佳翅片纵向间距与翅片长度和翅片厚度乘积的平方根的比为1.5～2.5,最佳翅片尺寸系数为3～5时,传热强化效果较好。     

Similarity retrieval of iconic image database

The perception of spatial relationships among objects in a picture is one of the important selection criteria to discriminate and retrieve the images in an iconic image database system. The data structure called 2D string, proposed by Chang et al., is adopted to represent symbolic pictures. The 2D string preserves the objects' spatial knowledge embedded in images. Since spatial relationship is a fuzzy concept, the capability of similarity retrieval for the retrieval by subpicture is essential. In this paper, similarity measure based on 2D string longest common subsequence is defined. The algorithm for similarity retrieval is also proposed. Similarity retrieval provides the iconic image database with the distinguishing function different from a conventional database.     

MRI fuzzy segmentation of brain tissue using neighborhood attraction with neural-network optimization.

Image segmentation is an indispensable process in the visualization of human tissues, particularly during clinical analysis of magnetic resonance (MR) images. Unfortunately, MR images always contain a significant amount of noise caused by operator performance, equipment, and the environment, which can lead to serious inaccuracies with segmentation. A robust segmentation technique based on an extension to the traditional fuzzy c-means (FCM) clustering algorithm is proposed in this paper. A neighborhood attraction, which is dependent on the relative location and features of neighboring pixels, is shown to improve the segmentation performance dramatically. The degree of attraction is optimized by a neural-network model. Simulated and real brain MR images with different noise levels are segmented to demonstrate the superiority of the proposed technique compared to other FCM-based methods. This segmentation method is a key component of an MR image-based classification system for brain tumors, currently being developed. Index Terms-Improved fuzzy c-means clustering (IFCM), magnetic resonance imaging (MRI), neighborhood attraction, segmentation.