关键技术在央视国际网络中的应用

本文根据央视国际网络技术系统建设的实践经验，着重探讨了大型媒体网站在大信息量（视音频和图文）、大访问量以及各种形式的网络互动应用环境下，技术系统中所涉及的关键技术的应用。本文还结合央视国际网络技术系统平台，从体系结构、视音频图文发布、制作、检索、应用软件、在线主持、邮件分发等方面对相关技术进行了探讨和介绍。     

关键技术在央视国际网络中的应用(二)

作为一个大型媒体网站，流媒体节目的制作和播出是央视国际网络的一个重要组成部分。网络音视频制作系统必须具备采集、编辑、储存、转码等功能，并可以同时满足不同宽带节目制作的要求。音视频制作系统由素材上载设备、非线编设备、统一存储设备、宽窄带压缩设备和压缩调度服务器五个部分组成。     

汽车—铁路联合运输方式的改进

本文提出了汽车－铁路联合运输的新式转载方式。这种转载方式利用索斗铲作转载设备，它在集运水平上不仅转载自卸汽车从工作面的矿岩，还挖掘自身所在工作面的爆堆中的矿岩。与传统的电铲或给料机式转载站相比，这种转载站作业稳定、基建量少、转载设备作业率高和工艺组织简单，在条件适宜（例如利用双向两开采的露天矿）时有实际推广应用的前景。     

固井水泥用量计算的研究

水泥用量是固井作业的重要参数。以往的计算公式均以电测井径为依据,误差较大。本文根据实际固井资料提出了计算水泥用量的新公式,它消除了电测井径不准产生的不确定问题,为准确计算固井水泥用量开辟了一条新途径。     

Acoustic microscopy and nonlinear effects in pressurized superfluid helium

The operation of an acoustic microscope having a resolution of 15 mm has been demonstrated. It uses as a coupling medium superfluid (4 )He colder than 0.9 K and pressurized to greater than 20 bar. The microscope has been used to image objects that show little or no contrast on a scanning electron microscope. In addition, the acoustic microscope has been used to study the properties of sound propagation in the coupling fluid. At low acoustic intensities, the coupling fluid has very low acoustic attenuation at the microscope's operating frequency (15.3 GHz), but near the focal point the acoustic intensity can be high enough that the helium behaves with extreme nonlinearity. In fact, this medium is capable of entering new regimes of nonlinear interaction. Plots of the received signal versus input power display a nearly complete source depletion at certain input power levels and a reconversion to the source frequency at higher power levels. Arguments that the process underlying this nonlinear behavior is harmonic generation are presented.     

A method for quantitative display of three-dimensional regional myocardial function

The DSR (dynamic spatial reconstructor), a multiple X-ray source scanner that generates stop action three-dimensional (3-D) images of a cylindrical volume, was used for quantitative imaging of left ventricular 3-D wall geometry and function in experimentally induced canine left ventricular myocardial infarction. Impaired regional myocardial function was induced by myocardial ischemia or infarction in four mongrel dogs by closed-chest occlusion of the proximal left anterior descending (LAD) coronary artery. At intervals of 6-14 weeks post occlusion, the dogs were scanned with the DSR during biatrial contrast injection. The 3-D shape, extent, and function of hypokinetic myocardium was measured from the DSR images utilizing measurement of the rate of local systolic wall thickening to detect regions of normal, ischemic, or scarred myocardium. The results were compared to scar size and anatomic distribution measured at postmortem examination. The anatomic extent and relationship of hypocontractile to normally contracting muscle was visualized by computer generated, pseudo 3-D shaded surface displays of the left ventricular chamber and by topographic projections of regional wall thickening rates onto a map of the left ventricular endocardial surface. The location of myocardial infarction and the surrounding zone of impaired function is clearly defined by this 3-D CT scanning procedure. The display method presented here provides both localization and quantification of the volume of ischemic and infarcted myocardium.     

正交法对咖啡因提取与纯化工艺的优化研究

利用正交实验法优化提取茶叶中咖啡因，178℃升华进行产品纯化，产品经薄层色谱及紫外分光光度法进行鉴定和含量测量，获得白色长针状晶体，纯度98.7%，产率1.94%。该工艺节约成本，减少工时，操作简便，产品产率高，纯度好。