直射线CT技术的局限性

分析了利用弯曲路径旅行时进行直射线反演的若干结果,对直射线CT技术的局限性进行了讨论.研究认为,对所讨论的区域而言,若介质速率的相对变化较大时,运用反演的结果不能很好地确定区域的内部结构;而当介质速率的相对变化较小时,对5m左右的薄层,它亦只能确定速度异常区的存在,而不能很好地确定其速度异常的数值.     

宇宙学方法论初探

本文简单评述了宇宙学研究对象、研究方法的基本属性和宇宙学基本问题,着重探讨了宇宙学研究方法的特点:1.哲学观念的支配作用;2.宇宙学观测方法的特点;3.宇宙学理论推演的特点;4.模型方法.并从方法论和认识论角度对宇宙学中的一些尖锐问题作了讨论.     

SIR—1型短红外发射理疗器对脑血管的作用效应

以６０名大学生和２１例头晕、头痛患者为实验对象，通过实验前与实验后的脑血流图检测资料的分析，对比，验证ＳＩＲ－１型短红外发射理疗器对脑血管的作用效应。实验者经本理疗器对头部作用２０ｍｉｎ后，可出现脑血管扩张、紧张度降低、降力减小、流入时间缩短、流入容积速度变大等现象，对脑血管起 着良好作用。     

大型光学天文望远镜综述

本提出了90年代发展我国天望远镜的方案。     

浅谈GPS在工程测量中的应用

介绍了GPS的构成和定位技术在建立工程测量控制网、RTK下的碎部测量与放样、区域差分系统下碎部测量与放样以及变形监测中的应用。     

专利集市

高效红外线节能家用燃气灶高效红外线节能家用燃气灶是上海岚健环保节能设备有限公司最新推出的,应用全新的空气预混燃烧技术原理,结合家用燃气灶的技术特点研制开发的新型家用节能产品,可节约燃气40%,它是家用燃气炉头的换代新产品。在技术上取得多项重大突破,将燃气雾化燃烧并将热能转化为红外线辐射传递,比普通的大气式燃烧炉有如下优点:(1)预混雾化式燃烧,燃烧更完全充分;(2)尾烟净化,能有效掏对人体危害极大的一氧化碳、氮氧化物的生成,消除对人体健康危害的隐患,节能环保;(3)抗风性能好,使用安全可靠;(4)升温快、热值高、节能燃气45%…     

Pneumatic active suspension system for a one-wheel car model using fuzzy reasoning and a disturbance observer

This paper presents the construction of a pneumatic active suspension system for a one-wheel car model using fuzzy reasoning and a disturbance observer. The one-wheel car model can be approximately described as a nonlinear two degrees of freedom system subject to excitation from a road profile. The active control is composed of fuzzy and disturbance controls, and functions by actuating a pneumatic actuator. A phase lead-lag compensator is inserted to counter the performance degradation due to the delay of the pneumatic actuator. The experimental result indicates that the proposed active suspension improves much the vibration suppression of the car model.     

水上交通观测天数与交通量估计精度的关系

利用数理统计与概率论的有关理论,在定义了以置信区间的长度与船舶交通量日均估计值之比作为"相对误差"的基础上,得到了船舶交通量观测时间与精度关系的有关结论.该结论可作为港口规划、实施船舶定线制及确定无线电岸台交换机容量决策的参考依据.     

Raman crystal lasers in the visible and near-infrared

Raman lasers based on potassium gadolinium tungstate and lead tungstate crystals pumped by a≈120 ps Nd: YAG laser at 1.064/μm were developed. High reflection mirrors for the Stokes wavelength have been used to generate near-infrared and eye safe spectral region of 1.15 - 1.32/μm. Second harmonic generation of the generated Raman lasers was observed. Eifficient multiple Stokes and anti-Stokes picosecond generation in 64 crystals have been shown to exhibit stimulated Raman scattering on about 700 lines covering the whole visible and near-infrared spectrum. All stimulated Raman scattering (SRS) wavelengths in the visible and near-infrared spectrum are identified and attributed to the SRS-active vibration modes of these crystals.     

A weak El Nio event in 2002 detected by the astronomical observation

Using the length-of-day (LOD) data series derived from astronomical observations made by various modern space techniques, southern oscillation index (SOI) and anomalies of sea surface temperature (SST) in tropical Pacific Ocean, the inter-annual components of these data series are obtained by the technique of band filtering from January 1962 to October 2002. It is found that a new ENSO event has already occurred in 2002 and been detected by the interannual LOD. It is shown by the wavelet analysis that the component with a period of about 4-6 years and the quasi-biennial component are out of phase during 2001-2002, which consequently suggests that the new ENSO event cannot be a strong one.