On the choice of data transformation for modelling time series of significant wave height     

C. Cunha  C. Guedes Soares 《Ocean Engineering》1999,26(6):185

Autoregressive models have been shown to adequately model the time series of significant wave height. However, since this series exhibits a seasonal component and has a non-gaussian nature, it is necessary to transform the series before a model can be fit to the data. Two different transformations that have been used in earlier work are shown not to be appropriate for all types of applications. A third transformation is proposed here, which combines the better features of the two earlier ones and which is appropriate for simulation work. This is demonstrated with an example of a series from Figueira da Foz, a location of the Portuguese Coast.  相似文献   

恢复沉积构造原始产状要素的微机程序     

佟洁 《甘肃地质》1999,8(1):86-91

由于构造变动,改变了沉积岩层的原始水平状态,其中的沉积构造（砾石群或斜层理）的产状也随之发生了变化。因此,恢复其原始产状,是古水流分析的一项重要环节。以往是用吴氏（吴尔福,１９０２）网投影法完成的。现在提供设计的一微机程序,以快速、准确、批量及高效等优点弥补了旧法的诸多不足,为拟创新法的尝试。  相似文献   

计算机2000年问题对地震观测的影响及其预防方法          下载免费PDF全文

王庭选  范五基  王先  巴志萍  张惠芳 《地震工程学报》1999,21(3):343-344

简要分析了计算机２０００ 年问题对地震观测的影响．这些影响主要表现在各种应用软件方面．提出了几种预防方法,除了更换必要的观测仪器之外,还要解决各类软件的２０００ 年问题  相似文献   

Cliff retreat and talus development at the caldera wall of Mount St. Helens: Computer simulation using a mathematical model     

Hiroyuki Obanawa  Yukinori Matsukura 《Geomorphology》2008,97(3-4):697-711

To simulate the landform evolution at the caldera wall of Mount St. Helens, USA, a mathematical model for talus development was applied to model the topographic change during the 11years from the volcanic eruption, i.e., from formation of the cliff. Simulated results show that the topographic change is predicted to be large for about 10years after the eruption and to decline thereafter. If snow accumulation in the talus slope deposits is negligible, the talus top will not reach the cliff top within 300years after the eruption. Talus growth in Mount St. Helens was much faster than that in the Chichibu Basin, Japan. This may indicate the low strength and/or high weathering rate of the rockwall of Mount St. Helens, resulting in rapid production of debris and rapid retreat of the cliff.  相似文献   

Hawaii bibliographic database     

Thomas L. Wright  Taeko Jane Takahashi 《Bulletin of Volcanology》1998,59(4):276-280

 The Hawaii bibliographic database has been created to contain all of the literature, from 1779 to the present, pertinent to the volcanological history of the Hawaiian-Emperor volcanic chain. References are entered in a PC- and Macintosh-compatible EndNote Plus bibliographic database with keywords and abstracts or (if no abstract) with annotations as to content. Keywords emphasize location, discipline, process, identification of new chemical data or age determinations, and type of publication. The database is updated approximately three times a year and is available to upload from an ftp site. The bibliography contained 8460 references at the time this paper was submitted for publication. Use of the database greatly enhances the power and completeness of library searches for anyone interested in Hawaiian volcanism. Received: 1 June 1997 / Accepted: 17 September 1997  相似文献   

CT图象重建的算法优化和代码优化   总被引：4，自引：1，他引：3  

江根苗  连兵  刘晋军  王怀志 《CT理论与应用研究》2000,9(Z1):13-22

卷积反投影是CT图象重建的最重要算法作为一种线性处理,其基本算法并不复杂,但由于CT的数据量庞大,使得图象重建的计算十分耗时.国外CT大都采用基于64位CPU的工作站并配以专门为CT建象设计的阵列处理板,这种昂贵的造价数十万元的计算机系统对一般医院用户来说是很大的经济负担.相反我们一直采用通用PC工作站,不仅降低了成本,而且计算机可以得到迅速的升级.这样,为满足医院临床诊断和治疗对建象速度的需要,我们就必须对该算法进行优化,优化的效果也成为CT软件能否适应市场需要,能否最终产品化的关键.本文总结了针对CT图象重建分别在算法层次和代码层次上所做的优化工作.第一,在算法实现的层次上,(1)在反投影算法中,进行内外循环交换,将最内层循环的计算量最大限度地减少,(2)利用反投影算法的对称性,只计算出部分图象数据并对称得到其它图象数据,(3)根据不同的视野范围自动调整反投影的计算量,(4)充分利用FFT的特点,提高实数线性卷积的效率.(5)数据的行列交换,用于提高CPU对数据的存取速度.第二,在代码编程的层次上,充分利用新一代微机CPU--Pentium III提供的新资源、新指令和相应的代码优化工具软件,重新编写算法关键部分的程序代码,以提高程序的实际执行效率.在东大阿尔派全身CT扫描机CT-C2000上的实际测试表明,通过上述算法优化和代码优化,CT图象重建软件的运行速度提高了8倍以上,己达到了医院实际使用的要求.  相似文献   

经脾门静脉造影CT (CTSP)和超声对原发性肝癌诊断价值的对照研究     

邱士军  张雪林 《CT理论与应用研究》2000,9(2):28-30

目的是应用CTSP和超声（US）检查原发性肝癌（PHC）,比较其对PHC的诊断价值。材料和方法采用43例PHC行US和经脾门静脉造影CT,在门静脉期行全肝动态扫描,统计两种检查方法病灶的检出数,计算检出敏感性及定性准确性并进行统计学处理。结果得到43例PHC共显示病灶106个,US及CTSP的检出敏感性分别为：63.2％、91.5％CTSP和US比较有显著性差异（P＜0.01）,其定性准确性（96.9％）也明显高于US（79.1％）.结论是CTSP检查可明显提高检出PHC的敏感性,是确诊早期PHC的一种重要方法。  相似文献   

计算机互联网上时间传递的一种设计方案   总被引：1，自引：0，他引：1  

袁海波  李变  冯平  白燕 《时间频率学报》2000,23(1):45-52

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。  相似文献   

大型稀疏矩阵的压缩技巧及其应用算法研究     

张钟澍 《成都信息工程学院学报》1987,(2)

本文通过对目前流行的两类关于大型稀疏矩阵优化压缩设计技巧的分析,提出一种在矩阵加、乘算法中统一使用的压缩格式。文中提出的算法,无论是矩阵的输入或者运算结果的输出均采用统一的压缩格式,所以能方便地应用于矩阵链相加或相乘的运算,而且所用的存储量较少,也大大加快了运算速度。用FORTRAN77编制的两算法的标准子程序已经在DPS7机上调试成功。  相似文献   

SHORT COMMUNICATION SOL1:A PROGRAM FOR THE SIMULATION OF COMPLEX EQUILIBRIA USING A PERSONAL COMPUTER     

ALVAROIZQUIERDO  JOSE-LUISBELTRAN 《地理学报(英文版)》1988,(Z1)

The program SOL1,written in Turbo-PASCAL for use on a personal computers(IBM-PC orcompatible),has been developed for calculating the equilibrium concentrations of the species inmulticomponent ligand-metal mixtures of up to 21 components and 150 species.The main features arethe easy data input system,the possibility of three different tasks(calculating the composition of a singlesolution,simulating titration curves and calculating the species distribution as a function of pH)andprocedures for drawing the calculated curves on Roland DXY plotters.The program has been tested by astudy of six different complex systems.  相似文献