Effects of high-order nonlinear interactions on unidirectional wave trains   总被引：2，自引：0，他引：2  

Nobuhito Mori  Takashi Yasuda 《Ocean Engineering》2002,29(10):1233-1245

Numerical simulations of gravity waves with high-order nonlinearities in two-dimensional domain are performed by using the pseudo spectral method. High-order nonlinearities more than third order excite apparently chaotic evolutions of the Fourier energy in deep water random waves. The high-order nonlinearities increase kurtosis, wave height distribution and H_max/H_1/3 in deep water and decrease these wave statistics in shallow water. Moreover, they can generate a single extreme high wave with an outstanding crest height in deep water. High-order nonlinearities (more than third order) can be regarded as one cause of freak waves in deep water.  相似文献   

西北旅游落后现状的突破及列车旅游的新思路--兼论"西部之星"旅游列车的产品设计   总被引：1，自引：0，他引：1  

刘睿文  吴殿廷 《地域研究与开发》2006,25(1):88-92

近几年，西北地区的旅游业虽然取得了很大的成绩，但其发展相对于东部地区却显得落后，其主要原因之一就是西北地区的旅游资源过于分散，景点间距过大，由此导致游览行程过长，游览内容单薄，这在客观上影响了游客的选择。而与此同时，在国外，列车旅游早已作为各国旅游业的重要旅游产品为世人所熟知。文章从分析我国西北旅游业发展的现状入手，针对景点分散这一制约我国西部旅游业发展的客观不利因素，肯定了开发旅游列车产品的思路。作者以西北地区为例，结合目前我国旅游专列发展现状，提出开通“西部之星”旅游列车的构想，并进行了初步的设计。  相似文献   

A DYNAMIC MODE FOR RELATIONSHIP BETWEEN FLOOD/DROUGHT IN YANGTZE RIVER VALLEY AND LOW FREQUENCY WAVE ORIGINATED FROM TROPICAL SEA AREA     

MIAO Qiuju  XU Xiangde  YAO Wenqing  ZHANG Xuejin 《Acta Meteorologica Sinica》2002,16(3):272-281

According to statistic analysis on sea surface temperature(SST)anomaly features in theNorth Pacific in winters and springs prior to the summer flood/drought in the middle and lowerreaches of the Yangtze River(hereafter referred to as MLRY),a strong signal SST key area thataffects local flood/drought is put forward,that is the equatorial eastern Pacific.The response ofgeneral circulation in the Northern Hemisphere to SST anomaly in the key area is furtherinvestigated. The low frequency wave train structure of correlation between the eastern PacificSST and the height at 500 hPa in the Northern Hemisphere is also studied,which reflects thedynamic features of teleresponse of local flood/drought at extratropics to tropical SST anomaly.Through introducing SST anomaly in the strong signal area in numerical experiments,the flood inYangtze River Valley is successfully simulated and the similar wave train pattern in the flow field isobtained too.Altogether,the physical picture and dynamic mode of the flood in the Yangtze RiverValley are described in this work.  相似文献   

A new method of testing pile using dynamic P-S-curve made by amplitude of wave train     

Hu Yi-li  Xu Jun  Duan Yong-kong  Xu Zhao-yong  Yang Run-hai  Zhao Jin-ming 《地震学报(英文版)》2004,17(6):725-734

A new method of detecting the vertical bearing capacity for single-pile with high strain is discussed in this paper. A heavy hammer or a small type of rocket is used to strike the pile top and the detectors are used to record vibration graphs. An expression of higher degree of strain (deformation force) is introduced. It is testified theoretically that the displacement, velocity and acceleration cannot be obtained by simple integral acceleration and differential velocity when long displacement and high strain exist, namely when the pile phase generates a whole slip relative to the soil body. That is to say that there are non-linear relations between them. It is educed accordingly that the force P and displacement S are calculated from the amplitude of wave train and (dynamic) P-S curve is drew so as to determine the yield points. Further, a method of determining the vertical bearing capacity for single-pile is discussed. A static load test is utilized to check the result of dynamic test and determine the correlative constants of dynamic-static P(Q)-S curve. Foundation item: Key projects of the tenth Five-year Plan of Yunnan Province (documented Yunnan district [2002]54-02-02) and Geophysical Society of Yunnan Province.  相似文献   

Numerical simulation of the response of a reinforced wall to a high speed train passage          下载免费PDF全文

A. Corfdir  E. Bourgeois  J.‐B. Payeur 《国际地质力学数值与分析法杂志》2017,41(11):1285-1303

The dynamic response of a mechanically stabilized earth wall to the passing of a high‐speed train is modelled using the finite element method. A three‐dimensional analysis is carried out, using a specific framework that allows performing the analysis with a moderate computational effort. In the first place, a so‐called multiphase approach is used to take into account the reinforcing strips. The moving load is taken into account by performing the calculation in a mobile referential using the properties of symmetry of the train cars and a simplifying assumption of periodicity for the whole train. We also assume a steady state. A partial validation of the approach is obtained by means of a comparison with an analytical solution. The quick increase in displacements induced by the train passing when the speed comes close to the celerity of Rayleigh waves clearly appears in the results. The vertical displacements, vertical stresses in the backfill, tensile forces in the strips and the influence of the stiffness of the soil are discussed. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

天气尺度波列对长江中下游6月梅雨的影响   总被引：2，自引：2，他引：0       下载免费PDF全文

黄海燕  王亚非  何金海  陈圣劼  秦坚肇 《大气科学学报》2016,39(1):28-36

采用1979—2007年6月NCEP/NCAR2.5°×2.5°逐日再分析资料和中国743站逐日降水资料,利用相关分析、合成分析等方法,分析了天气尺度波列的特征及其对长江中下游6月梅雨的影响。结果表明:当长江中下游6月梅雨较少时,东亚及西太平洋区域存在一个天气尺度波列;该波列的延伸距离较短(从黄河河套地区经过长江中下游至南海、菲律宾海一带),维持时间也很短,且仅仅在500 h Pa以下较强。诊断及个例分析表明,当该波列异常显著时,长江中下游梅雨降水明显减少,而其南部区域降水则增多,说明该波列对预报长江中下游降水具有重要的指示意义。  相似文献   

秋季北极海冰对EP型ENSO的非线性响应          下载免费PDF全文

祁莉  马威威  何金海  耿新 《大气科学学报》2019,42(1):117-128

利用1961—2015年Hadley中心逐月海表温度资料、海冰密集度资料以及NCEP/NCAR再分析资料,探讨了秋季北极海冰对于EP型ENSO事件的异常响应,并进一步研究了这种异常响应的可能原因。结果表明,秋季北极海冰对EP型ENSO的响应具有非线性,特别是喀拉海海域(60°～90°E,70°～80°N)海冰无论在EP型El Ni?o或是La Ni?a位相,均表现为显著的负异常。进一步研究发现,不同ENSO位相造成该区域海冰异常偏少的机制有明显不同。EP型El Ni?o年秋季菲律宾附近海域对流活动被抑制,所激发的经向波列在高纬地区形成异常反气旋环流,其南风分量向喀拉海输送暖平流,造成海冰异常偏少。而EP型La Ni?a年喀拉海海域则主要受到来自大西洋开放性海域西风异常的影响,合成结果和个例年均显示EP型La Ni?a年秋季北大西洋上空存在一个显著的西风急流中心,有利于北大西洋开放性海域较暖海水向下游输送,进而影响喀拉海海冰。这些结果表明,热带外地区大气环流场对EP型ENSO的非线性响应导致了喀拉海海冰对EP型ENSO事件的响应也表现出明显的非线性。  相似文献   

冬、夏季青藏高原地面加热场激发的500hPa遥相关型   总被引：3，自引：0，他引：3  

李超 《高原气象》1994,13(2):122-127

本文用青藏高原地面加热场强度来表征高原的加热状况，并用统计的方法，分析了冬季（２月）和夏季（７月）青藏高原地面加热场强度与同期５００ｈＰａ位势高度的遥相关关系，得到如下结论：冬季高原地面加热场可激发北半球５００ｈＰａ产生遥相关型，这种遥相关型可看成是二维Ｒｏｓｓｂｙ波列由低纬向东北方向传播；夏季高原地面加热场可激发北半球５００ｈＰａ产生类似于ＥＵ型的遥相关，这种遥相关型可看成二维Ｒｏｓｓｂｙ波列由  相似文献   

6月份格陵兰海冰异常对黄河中上游7月份旱涝的影响   总被引：2，自引：0，他引：2       下载免费PDF全文

胡增臻 《应用气象学报》1995,6(3):366-372

通过北极4个区的海水DQ%指数和全国160站7月份降水关系的诊断分析指出，6月份格陵兰海冰异常与黄河中上游7月份旱涝存在着明显的联系，6月份格陵兰海冰少(多)时，黄河中上游7月份易涝（旱）。产生这种联系的物理机制是6月份格陵兰海冰异常影响7月份欧亚大气环流，导致黄河中上游7月份降水产生异常。通过对相关场进行显著性检验，确认了6月份格陵兰海冰异常与黄河中上游7月份旱涝联系在统计上的可靠性。同时发现，有时随机数序列与气象要素场的相关场会达到很高的显著水平，而且这种相关场中的显著相关区的分布并不是杂乱无章的，而是成片分布的。这项工作指出了把对相关场的显著性检验与相关场成因的物理机制分析相结合的必要性。  相似文献   

Elastic waves in visco-elastic half-space generated by various vehicle loads   总被引：2，自引：0，他引：2  

H. -H. Hung  Y. -B. Yang   《Soil Dynamics and Earthquake Engineering》2001,21(1):1

In this paper, the response of a visco-elastic half-space subjected to moving loads with static and dynamic components is investigated. Four types of vehicle loads are considered, including the moving point load, uniformly distributed wheel load, elastically distributed wheel load, and a train load simulated as a sequence of elastically distributed wheel loads. In each case, the influence of the moving loads traveling in the subsonic, transonic and supersonic ranges on the dynamic responses of the half-space is studied. The parametric study conducted herein enables us to grasp insight into the mechanism of wave propagation for a visco-elastic half-space under moving loads.  相似文献