北斗广播电文钟差模型精度评估及改善策略

星载原子钟是北斗卫星导航系统(BDS)的核心设备,其钟差模型是北斗广播电文的重要组成部分,模型精度直接影响BDS的服务性能.本文采用星地双向时频传递(TWSTF)钟差测量为参考,评估了BDS广播电文钟差模型精度,结果表明BDS广播电文钟差模型精度优于2 ns(数据龄期小于12 h).针对BDS广播电文钟差参数解算问题,...     

闽台茶文化创意产业合作发展的思考

文化创意产业作为知识经济时代的一种新型产业业态模式,是文化产业化的必然结果.在闽台合作不断深入的背景下,扩大并加深闽台两岸地区在文化创意产业方面的合作尤为重要.本研究以茶文化作为切入点,对适合闽台两地文化创意产业合作的新型方式做出相关思考.     

The coastal transition at the mouth of a small mountainous river in Taiwan

The Tseng-wen River is a small mountainous river in southern Taiwan that has distinct dry and flood seasons. Several lines of evidence have revealed that the depositional system at the mouth of the river has transformed from a deltaic system to an estuarine system. The evidence includes long to short-term shoreline changes, geomorphology of the river mouth, mixed sediment sources inside the river mouth, mixing and suspended sediment characteristics inside the river mouth, and the grain-size distribution patterns on the river bed. Unlike the long-term evolution of many other coastal systems, the transformation at the Tseng-wen River mouth is largely caused by the building of a reservoir in the middle reaches of the river. The present study provides an example that coastal environments can be influenced by human activities farther inland on a time scale much faster than what would occur naturally.     

深海潜标ADCP 的实时数据传输

深海潜标观测是深海观测获取长周期海洋科学数据的重要调查手段,由于深海海域环境非常复杂,潜标易丢失或终止正常工作,造成重大损失.本研究基于铱星卫星数据通信模块,开发与深水潜标上安装的RDt 75k ADCP相匹配的数据解析压缩软硬件,建立一套远程实时获取潜标ADCP数据的传输系统,实现对深海潜标ADCP的实时监测.     

青藏铁路冻土区环境问题对工程安全可靠性影响

本文分析了青藏铁路冻土区主要工程对多年冻土温度、水分特征和冻土环境特征的影响,探讨了冻土区工程环境与冻土环境之间相互作用特点。进而论述了控制外界对冻土工程环境系统的热侵蚀是保证冻土区工程安全可靠性的关键问题。     

锦屏电站坝厂区卸荷岩体力学参数研究

选择具有代表性的区块,根据结构面的性状和规模拟定模型层次和尺寸,建立岩体数值仿真模型,通过计算机数值仿真,采用卸荷非线性力学理论对锦屏电站坝厂区岩体进行卸荷岩体宏观力学特性及参数的数值分析;同时,用RMR法和BP神经网络法对岩体宏观力学特性及参数进行分析,综合确定岩体力学参数,为设计部门提供设计参考依据.     

东营凹陷下第三系深部碎屑岩储层次生孔隙垂向分布及成因分析

东营凹陷下第三系埋深大于 30 0 0 m的深部碎屑岩储层普遍发育 2～ 4个次生孔隙带 ,Φ=10 %～ 30 % ,K=0 .1× 10 - 3μm2～ 30× 10 - 3μm2 ,为中孔低渗低孔低渗油气储层。综合有机质热演化过程、成岩作用和构造断裂等分析 ,认为东营凹陷埋深大于 30 0 0m碎屑岩地层中 ,第一、二个次生孔隙带埋深在 30 0 0 m～ 390 0 m之间 ,其形成主要与有机质成熟过程释放有机酸对长石等颗粒的溶解有密切关系 ,在深大断裂附近储层同时受到大气淡水的影响 ,而深陷带包裹于暗色泥岩中的浊积砂岩的次生孔隙发育情况还与泥质岩异常压力带有关 ;第三个次生孔隙带埋深一般为 390 0 m～ 430 0 m,主要成因于粘土矿物转化造成的还原环境 ,同时受到硫酸盐热化学氧化还原反应的影响。这三个次生孔隙发育带对储集油气有效。第四个孔隙发育带埋深在 470 0 m以下 ,主要是构造成因的微裂缝 ,较难成为有效的油气储层。     

水平荷载下导管架平台桩基础的非线性有限元分析

导管架平台桩基础的控制荷载主要为风荷载、波浪荷载、地震荷载等水平荷载,为研究水平荷载下导管架平台桩基础的承载特性,采用非线性有限元分析方法对水平荷载下桩-土之间的相互作用进行研究,提出了有效模拟桩基水平承载特性的有限元模型,分析了模型桩的刚度、直径、土质参数中水平土压力系数、剪胀角对桩基承载特性的影响及水平荷载下群桩承载特性,并将有限元计算结果与API规范及模型试验结果进行对比。研究结果表明,非线性有限元分析方法分析水平荷载下桩-土相互作用是可行的,计算结果可为导管架平台的桩基设计提供参考。     

Modeling of the eddy viscosity by breaking waves

Breaking wave induced nearsurface turbulence has important consequences for many physical and biochemical processes including water column and nutrients mixing,heat and gases exchange across air-sea interface.The energy loss from wave breaking and the bubble plume penetration depth are estimated.As a consequence,the vertical distribution of the turbulent kinetic energy(TKE),the TKE dissipation rate and the eddy viscosity induced by wave breaking are also provided.It is indicated that model results are found to be consistent with the observational evidence that most TKE generated by wave breaking is lost within a depth of a few meters near the sea surface.High turbulence level with intensities of eddy viscosity induced by breaking is nearly four orders larger than υwl(=κuwz),the value predicted for the wall layer scaling close to the surface,where uw is the friction velocity in water,κ with 0.4 is the von Kármán constant,and z is the water depth,and the strength of the eddy viscosity depends both on wind speed and sea state,and decays rapidly through the depth.This leads to the conclusion that the breaking wave induced vertical mixing is mainly limited to the near surface layer,well above the classical values expected from the similarity theory.Deeper down,however,the effects of wave breaking on the vertical mixing become less important.     

计算机互联网上时间传递的一种设计方案

目前,国内外时间传递方式主要有长波授时、短波地、电话授时、双星比对、ＧＰＳ时间信息等。信息产业的不断发展,使得互联网络已成为一种新的信息传递手段和资源共享方式 。通过计算机网络传输标准时间、频率将是授时领域的新课题,也是时间同步的新手段。讨论了计算机互联网上时间传递的一种设计方案,给出利用计算机网络系统实现标准时间的传递的具体方法,并介绍一种计算机互联网时间传递软件的使用方法等。