对ADSL接入方式铜缆可用线对率的分析

指出了为发展ADSL而提高市话音频铜线电缆的传输质量和维护水平的必要性,分析了铜线电缆线对有关指标参数低劣的原因和对传输ADSL的影响,并提出了一些改进的意见。     

固定式宽带无线接入技术--LMDS

本地多点分配业务(LMDS)是近年来在国际上兴起的固定式宽带无线接入技术,具有传输容量大、起始费用低的优点,受到了国内外电信业务经营者的普遍关注.文章介绍了LMDS提供的业务类型、工作频率、系统结构和标准化情况,并将LMDS与有线电视网络、ADSL、MMDS等现有的接入技术进行了比较.文章认为LMDS的商业推广尚需解决信号质量、服务区尺寸、费用等制约因素.     

Transport properties of 1,1-difluoroethane (R152a)

Based on reliable. carefully selected data sets. equations for the thermal conductivity and the viscosity of the refrigerant R 112a are presented. They are valid at temperatures from 240 to 440 K, pressures up to 20 MPa. and densities up to 1050 kg · m^–3. including the critical region.     

Application of Wavelet Packet De-noising in Time-Frequency Analysis of the Local Wave Method

The local wave method is a very good time-frequency method for nonstationary vibration signal analysis. But the interfering noise has a big influence on the accuracy of time-frequency analysis. The wavelet packet de-noising method can eliminate the interference of noise and improve the signal-noise-ratio. This paper uses the local wave method to decompose the de-noising signal and perform a time-frequency analysis. We can get better characteristics. Finally, an example of waveletpacket denoising and a local wave time-frequency spectrum application of diesel engine surface vibration signal is put forward.     

Effects of luminance,wavelength and purity on the color attributes: Brief review with new data and perspectives

A color stimulus may be characterized by three psychophysical dimensions (luminance, dominant wavelength, and purity), whose corresponding color attributes are lightness, hue, and chroma/colorfulness. The 3 × 3 matrix gives nine basic effects of the psychophysical dimensions on the color attributes (e.g. the effect of luminance on hue), but there are 49 possible combinations as more complex effects (e.g. the effect of luminance on hue and chroma, i.e. on chromaticity). Researching and quantifying such effects enables modelling of the underlying neural mechanisms and of color appearance. Using a simple nomenclature to identify the effects (e.g. Ph denotes the effect of Purity on hue), this paper briefly reviews and interrelates 15 of the commonest effects, giving new data or new graphical perspectives to clarify or fill gaps in the literature. Contrast and no‐contrast effects (stimuli viewed simultaneously or singly, respectively) are differentiated. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 208–222, 2007     

榆林气田低产低效井开发分析评价

榆林气田自1999年投入开发以来,产能建设大幅提高,生产规模成倍增长。随着气田开发规模的扩大,气井数量成倍增加,低产低效井的数量随之增加,对低产低效期间加强研究意义重大。以理论知识为指导,利用开发生产资料对榆林气田低产低效气井的地质特征,开发现状,管理制度,下步开发措施等方面予以分析与研究,提出具体建议或措施;寻找榆林气田低产低效井合理的开发方式及生产模式。     

瓦斯燃烧器回流区测试

燃烧器流场内回流区的大小和形状决定了燃烧火焰的稳定性 ,利用APV激光测速系统 ,在燃烧器冷态测试实验装置上对一瓦斯燃烧器冷态模型的流动进行了研究 ,发现了该燃烧器流场内的双回流区结构 ,并得到了中心回流区尺寸与稳焰器结构的关系 ,为该结构类型燃烧器的稳焰设计及稳焰能力的评价提供了实验依据     

用C++ Builder实现数字图像的平滑处理

介绍了图像增强技术中，空间域处理方法中的邻域平均法的原理、算法，及该原理在windows平台上以C＋＋ Builder为开发工具的具体程序实现。     

城市建设的休克疗法——大连现象解说

在启动大规模的现代化建设的进程中，应对发展中听中型城市实施“休克疗法”，强调性终止城市发展的无序而缓慢的自然进程。选择短暂的“回归”或“中断”历史的调整时，应以能否适当地的历史文化特质从而把握当代的发展机遇为依据。     

局域网视频广播接收器的设计

描述了一个局域网视频广播接收器的设计。发送端以计算机按UDP/IP的方式向局域网中发送视频广播，在接收端利用FPGA器件设计的接收器对广播进行接收、缓冲、格式转换，以电视作为显示终端，并介绍了在FPGA器件中所设计的各个模块。