基于T梁三维声波模拟信号的S变换时频分析技术

混凝土T梁在我国桥梁建设中发挥了越来越重要的作用,由于其结构的复杂性,目前基于T梁预应力束孔管道无损检测方法正处于理论探究阶段.三维声波数值模拟作为一种有效的、常规的正演手段被大量的应用于合成记录的生成中,本文参照实际T梁模型的大小设置了一组模型参数,并进行了三维声波数值模拟,分析了不同位置所接收到的多道记录信号,给出了不同时刻剖面的波场快照图.同时,采用了S变换时频分析方法,提取了频率为25Hz时间域的能量分布图,得到了数值模拟信号的时频联合特征,在S变换时频剖面上能更加清晰的识别低速异常体的分布位置.结果表明:声波法可用于T梁预应力束孔管道无损检测中,S变换时频分析方法有助于提高声波数据解释的准确性.     

Assessing spatial pattern of urban thermal environment in Shanghai, China

The aggravating urban thermal environment has considerable adverse effects on urban physical environment, energy consumption, and public health. Due to the complexity of factors contributing to the urban thermal environment, traditional statistical methods are insufficient for acquiring data and analyzing the impacts of human activities on the thermal environment, especially for identifying dominant factors. Based on thermal remote sensing imageries and Geographic Information System analysis, we assessed spatial pattern of urban thermal environment in Shanghai in 2008, and analyzed the factors contributing to the generation of urban heat island (UHI) using principal component analysis (PCA). We found that Shanghai had obvious UHI with uneven spatial pattern in 2008. Further, we identified three most important components leading to the variances of Shanghai’s UHI: the gradient from man-made to natural land cover, landscape configuration, and anthropogenic heat release. A linear model has thus been successfully constructed, implying that PCA is helpful in identifying major contributors to UHI. The findings are of significance for policy implication to urban thermal environment mitigation.     

浅谈地震灾害符号体系构建的理论框架

地震灾害符号的研究已经成为地震应急工作的一项重要内容,本文借助于符号学及传播学的方法论,在分析地震灾害符号的符号学内涵、使用人群和传播内容的基础上,探讨了地震灾害符号体系的特点及构建原则。地震本身的特殊性和破坏性决定了地震灾害符号体系的特殊性和时间性,本文在遵循实用性、主次性及概括性三个原则的前提下,提出了一套地震灾害符号体系构建的理论框架,可为地震灾害符号体系的构建和深入研究提供参考。     

Study on the high precision acoustic measurement techniques for determining temperature field around seafloor hydrothermal vent

This paper presents the basis of acoustic method used for temperature field measurement of seafloor hydrothermal vent and two techniques of the parabolic interpolation and the bending compensation of propagation paths of acoustic signal are introduced. Experimental research is performed to exactly rebuild the temperature field around hot springs on the floor of Qiezishan Lake, Yunnan, China. The accuracy of the travel time estimation has been improved based on the aforementioned technique and method. At the same time, by comparison of the results of temperature field with different means, the max absolute error, the maximum relative error and the root mean square error are given. It shows that the technique and the method presented in the paper can be applied to the temperature field measurement detector around the seafloor hydrothermal vent. It also has a good accuracy.     

近60年西北太平洋台风年代际变化特征及成因的初步分析

利用60年台风资料,对西北太平洋台风的频数、路径和强度变化做统计分析。结果表明:西北太平洋的台风活动在20世纪60年代是高峰期,70年代则是低谷期,从20世纪90年代后期开始,台风活动总体处于低谷期;台风路径主要以转向为主,在20世纪60、70年代平均路径比较偏南,而进入21世纪后平均路径比较偏北;强度在20世纪50、60年代总体较强,后25年总体较弱;西北太平洋台风异常偏多时,西北太平洋副高弱且位置偏东,太平洋海温分布呈"拉尼娜"特征;台风异常偏少时,副高强且位置偏西,太平洋海温分布呈"厄尔尼诺"特征。     

南堡油田海域的冰情对工程作业的影响

通过对2005-2011年冬季南堡油田海域海冰监测资料进行统计、分析,给出了该海域海冰时空分布特征,在分析了海冰对海上工程作业的影响以及海冰防灾减灾所面临形势的基础上,结合油田实际提出了防冰减灾工作的具体建议.     

Future projection of East China Sea temperature by dynamic downscaling of the IPCC_AR4 CCSM3 model result

Future temperature distributions of the marginal Chinese seas are studied by dynamic downscaling of global CCSM3 IPCC_AR4 scenario runs.Different forcing fields from 2080-2099 Special Report on Emissions Scenarios(SRES) B1,A1,and A2 to 1980-1999 20C3M are averaged and superimposed on CORE2 and SODA2.2.4 data to force high-resolution regional future simulations using the Regional Ocean Modeling System(ROMS).Volume transport increments in downscaling simulation support the CCSM3 result that with a weakening subtropical gyre circulation,the Kuroshio Current in the East China Sea(ECS) is possibly strengthened under the global warming scheme.This mostly relates to local wind change,whereby the summer monsoon is strengthened and winter monsoon weakened.Future temperature fluxes and their seasonal variations are larger than in the CCSM3 result.Downscaling 100 years’ temperature increments are comparable to the CCSM3,with a minimum in B1 scenario of 1.2-2.0°C and a maximum in A2 scenario of 2.5-4.5°C.More detailed temperature distributions are shown in the downscaling simulation.Larger increments are in the Bohai Sea and middle Yellow Sea,and smaller increments near the southeast coast of China,west coast of Korea,and southern ECS.There is a reduction of advective heat north of Taiwan Island and west of Tsushima in summer,and along the southern part of the Yellow Sea warm current in winter.There is enhancement of advective heat in the northern Yellow Sea in winter,related to the delicate temperature increment distribution.At 50 meter depth,the Yellow Sea cold water mass is destroyed.Our simulations suggest that in the formation season of the cold water mass,regional temperature is higher in the future and the water remains at the bottom until next summer.In summer,the mixed layer is deeper,making it much easier for the strengthened surface heat flux to penetrate to the bottom of this water.     

Pollen morphology of selected tundra plants from the high Arctic of Ny-(A)lesund, Svalbard

Documenting morphological features of modem pollen is fundamental for the identification of fossil pollen, which will assist researchers to reconstruct the vegetation and climate of a particular geologic period. This paper presents the pollen morphol- ogy of 20 species of tundra plants from the high Arctic of Ny-Alesund, Svalbard, using light and scanning electron microscopy. The plants used in this study belong to 12 families： Brassicaceae, Caryophyllaceae, Cyperaceae, Ericaceae, Juncaceae, Papav- eraceae, Poaceae, Polygonaceae, Ranunculaceae, Rosaceae, Salicaceae, and Scrophulariaceae. Pollen grain shapes included： spher- oidal, subprolate, and prolate. Variable apertural patterns ranged from 2-syncolpate, 3-colpate, 3-（-4）-colpate, 3-（-5）-colpate, 3-colporate, 5-poroid, ulcerate, ulcus to pantoporate. Exine ornamentations comprised psilate, striate-perforate, reticulate, mi- croechinate, microechinate-perforate, scabrate, granulate, and granulate-perforate. This study provided a useful reference for com- parative studies of fossil pollen and for the reconstruction of paleovegetation and paleoclimate in Svalbard region of Arctic.     

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Geographical differences and influencing factors of rural energy consumption in Southwest mountain areas in China: A case study of Zhaotong City

China is a mountainous country,and Southwest mountain areas cover the most mountain areas in China and have the most serious problems.Taking Zhaotong city as the study area,based on 902 rural household questionnaires of 11 villages in 2 counties and Tobit model,this paper analyzes the geographical differences and influencing factors of energy consumption for non-production purposes of rural households living in different terrain conditions.This research finds that:(1) Coal takes up the main part of energy consumption in valley areas and coal consumption is mainly affected by per capita cultivated land area,household income,proportion of rural household energy expenditure in total expenditure,coal price,and family population size.Firewood takes up the main part of energy consumption in high mountain areas and firewood consumption is mainly affected by per capita firewood forest area,distance to purchase coal,household income,electricity price,and coal price.(2) Only when the distance is greater than 20 kilometers,that is the average distance of rural households living in middle mountain areas(1,600m~1,800m) to purchase coal,the transportation condition has a significant impact on coal consumption.(3) In high mountain areas,prices of coal and electricity are the main factors influencing energy consumption choice of rural households.Too high prices of coal and electricity would to some extent lead rural households to choose firewood as the main energy consumption type.Compared to coal,rural households prefer to choose electricity.