Rayleigh Wave Tomography of Ningxia and Its Adjacent Areas Based on Ambient Noise

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盛夏中国弱台风大暴雨事件的可预报性

Climate Change Research Letters 气候变化研究快报, 2019, 8(4), 365-372Published Online July 2019 in Hans. /journal/ccrlhttps:///10.12677/ccrl.2019.84041Predictability of Weak Typhoon HeavyRainfall Event in China during theMidsummerXifan Zhang1,2, Fei Huang 1,2,3*, Shibin Xu1,21Physical Oceanography Laboratory/CIMST, Ocean University of China, Qingdao Shandong2Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao Shandong3 Ningbo Collabrative Innovation Center of Nonlinear Hazard System of Ocean and Atmosphere,Ningbo University, Ningbo ZhejiangReceived: May 20th, 2019; accepted: May 28th, 2019; published: Jun. 4th, 2019AbstractTyphoon occurs the most frequently in midsummer over China, and typhoon precipitation is an important part of precipitation in China. It is generally believed that after landing typhoon wea-kened, the accompanying strong storms and rainfalls will also be weakened. However, sometimes heavy rainstorm appears while the typhoon intensity weakens. This paper defines the “weak ty-phoon heavy rainfall” event, that is, the tropical cyclone does not reach the typhoon-class intensity (averaged wind speed of the tropical cyclone in 2 minutes is less than 32.7 m/s), and daily preci-pitation at each station exceeds 100 mm (the heavy rainstorm level). And by exploring the predic-tability and interannual variation of WTHRE, the results show that the abnormal warmth of the Barents Sea in the early sea temperature field caused the sea ice to decrease, which made the cold air activity southward, and cooperated with the positive phase of the previous IOD, which leads the cross-equatorial airflow enhanced in summer and a large amount of vapor transport north-ward carried with the South summer monsoon, which increases the precipitation in China. The combination of the La Niña-SST signal in the background field of the PDO cold phase and the wea-kening of the West Pacific subtropical high caused the increase of typhoon affecting China with weak intensity, which induced the WTHRE.KeywordsWeak Typhoon, Heavy Rainfall, Typhoon Precipitation, Predictability盛夏中国弱台风大暴雨事件的可预报性张希帆1,2，黄菲1,2,3*，许士斌1,2*通讯作者。

宁夏中药材产业特色发展探索研究

宁夏农林科技，Ningxia Journal of Agri.and Fores.Sci.&Tech.2023，64（02）：60-63基金项目：宁夏农林科学院科技创新专项（NKYJ-21-01）。

作者简介：刘俭（1975—），女，四川成都人，工商管理硕士，研究员，主要研究方向为农业经济管理。

收稿日期：2022-12-23修回日期：2023-01-04宁夏是西北地区药用植物种质资源的典型代表区域和资源优势突出的“天然药库”，是我国道地中药材枸杞、甘草、银柴胡、菟丝子等的重要产区。

宁夏药用植物资源种类繁多，近年来，宁夏回族自治区党委、政府高度重视中药材产业发展，把中药材产业作为推动乡村振兴、促进农民增收的特色产业，宁夏中药材产业格局初步形成。

1宁夏中药材产业特色发展现状1.1产业发展基础条件良好宁夏全域属温带大陆性气候，日照充足、昼夜温差大。

中、北部适宜沙旱生药材生长，南部六盘山核心带药用植物资源丰富，有“黄土高原绿岛”美誉。

第四次全国中药资源普查结果显示，宁夏有152种常用中药材，占全国调查品种的三分之一。

宁夏甘草、银柴胡等种植基地具有独特的地理环境和气候条件，该基地种植的甘草、银柴胡等中药材品质优良，中药材有效成分、农药残留、重金属含量均符合绿色中药材质量要求。

2021年，宁夏中药材种植面积达11.0万hm 2，药材总产量达15.4万t，总产值超过50亿元。

1.2产业区域布局日趋完善以黄河、贺兰山、六盘山、罗山“一河三山”为坐标，宁夏中药材种植形成三大区域布局。

一是北部引宁夏中药材产业特色发展探索研究刘俭1，李晓瑞1，达海莉1，祁静竹2，刘永进31.宁夏农林科学院农业经济与信息技术研究所，宁夏银川7500022.银川市生产力促进中心，宁夏银川7500013.宁夏农业勘查设计院，宁夏银川750002摘要：中药材产业特色发展对于巩固脱贫攻坚成果、推进乡村振兴、实现绿色发展意义重大。

本文全面分析了宁夏中药材产业发展现状、存在短板、产业效益，提出加快宁夏中药材产业特色发展的对策和建议，包括挖掘特色资源、延伸产业链条、打造品牌体系等，为实现脱贫攻坚与乡村振兴有效衔接提供参考。

喜马拉雅东构造结岩石圈板片深俯冲的地球物理证据

喜马拉雅东构造结岩石圈板片深俯冲的地球物理证据姜枚;彭淼;王有学;谭捍东;李庆庆;张立树;王伟【摘要】We conducted broadband seismic observation and MT detection around the Namche Barwa from 2009 to 2010. P wave velocity perturbations down tn 300km were obtained and two electrical models were acquired by 2D inversion. There are similar features between electrical models and the corresponding tomographic images by joint interpretation. Our results show that the upper crust of Namehe Barwa is separated by IYS and consists of prominent high-velocity and resistive blocks. The mid-lower crust is inhomogenous and characterized by low-velocity and conductive anomaly. The Indian lithospheric mantle has subducted beneath Eurasian plate and its frontier has passed through the Jiali shear zone and reached the Bangong-Nujiang suture; A large-scale low-velocity anomaly is revealed within the Lhasa block beneath the high-velocity plate from 100km to 200km depth, above which the mid-lower crust is an extensive low-velocity conductor. This suggests that there exist channels beneath southeastern Tibetan Plateau favorable to weak and flowable materials exuding towards east and southeast, which gives geophysical evidence for the dynamics mode of deep-subduction of Indian Plate beneath the Namche Barwa.%2009～ 2010年在南迦巴瓦地区进行了宽频带地震和大地电磁探测,分别处理获得东构造结及其邻区的地下300km以上的P 波速度图像和两条大地电磁电阻率剖面.通过资料的对比和综合解释,发现电阻率分布与地震波速有较好的对应关系.研究结果表明:南迦巴瓦变质体的上地壳部分呈现明显高速高阻特征,为两侧的雅鲁藏布江缝合带所夹持；中下地壳具有不均匀性,且普遍呈低速低阻特征；印度板块在藏东南向欧亚板块的俯冲前缘越过嘉黎断裂,抵达班公湖-怒江缝合带；在拉萨地体的高速俯冲板片以下100km至200km深度范围内存在大规模的低速异常带,其上盘中下地壳也广泛发育低速高导体,指示青藏高原东南缘可能存在韧性易流动的物质向东、东南逃逸的通道,为印度板块在南迦巴瓦的深俯冲动力学模式提供了地球物理证据.【期刊名称】《岩石学报》【年(卷),期】2012(000)006【总页数】10页(P1755-1764)【关键词】宽频地震;大地电磁;板片深俯冲;东构造结;喜马拉雅【作者】姜枚;彭淼;王有学;谭捍东;李庆庆;张立树;王伟【作者单位】中国地质科学院地质研究所,大陆构造与动力学国家重点实验室,北京100037;中国地质科学院地质研究所,大陆构造与动力学国家重点实验室,北京100037;中国地质大学地球物理与信息技术学院,北京100083;桂林理工大学地球科学学院,桂林541004;中国地质大学地球物理与信息技术学院,北京100083;中国地质科学院地质研究所,大陆构造与动力学国家重点实验室,北京100037;中国地质科学院地质研究所,大陆构造与动力学国家重点实验室,北京100037;中国地质科学院地质研究所,大陆构造与动力学国家重点实验室,北京100037;中国地质大学地球物理与信息技术学院,北京100083【正文语种】中文【中图分类】P313图1 喜马拉雅东构造结宽频地震台站及大地电磁测点位置IYS-雅鲁藏布江缝合带；JSZ-嘉黎剪切断裂带；BNS-班公湖-怒江缝合带；NJBW-南迦巴瓦东构造结；LS-拉萨地体；QT-羌塘地体；HM-喜马拉雅地体；INDB-印度陆块Fig.1 Map ofthe location of broadband seismic stations and magnetotelluric sites in Eastern Himalayan SyntaxisIYS-Indus-Yarlung Tsangpo suture; JSZ-Jiali shear zone; BNS-Bangong-Nujiang suture; NJBW-Namche Barwa tectonic syntaxis; LS-Lasa terrain; QT-Qiangtang terrain; HM-Himalaya terrain;INDB-Indian block印度板块与欧亚板块的碰撞一直以来都为广大地质、地球物理学家所关注，喜马拉雅造山带被公认为是印度板块与欧亚板块相碰撞的结果(Argand，1924；Yin and Harrison，2000；Tapponnier et al.，2001；许志琴等，2006a，b)。

Predictability of Chinese Summer Extreme Rainfall Based on Arctic Sea Ice and Tropical Sea

J. Ocean Univ. China(Oceanic and Coastal Sea Research)https:///10.1007/s11802-019-3886-6ISSN 1672-5182, 2019 18 (3): 626-632/xbywb/E-mail:xbywb@Predictability of Chinese Summer Extreme Rainfall Basedon Arctic Sea Ice and Tropical Sea Surface T emperatureZHU Zhihui1), HUANG Fei2), 3), *, and XIE Xiao1)1) Shanghai Marine Meteorological Center, Shanghai 201306, China2) Key Laboratory of Physical Oceanography, Ocean University of China, Qingdao 266100, China3) Ningbo Collaborative Innovation Center of Nonlinear Harzard System of Ocean and Atmosphere, NingboUniversity, Ningbo 315211, China(Received April 11, 2018; revised January 15, 2019; accepted March 15, 2019)© Ocean University of China, Science Press and Springer-Verlag GmbH Germany 2019Abstract Chinese summer extreme rainfall often brings huge economic losses, so the prediction of summer extreme rainfall is necessary. This study focuses on the predictability of the leading mode of Chinese summer extreme rainfall from empirical orthogo-nal function (EOF) analysis. The predictors used in this study are Arctic sea ice concentration (ASIC) and regional sea surface tem-perature (SST) in selected optimal time periods. The most important role that Arctic sea ice (ASI) plays in the appearance of EOF1 may be strengthening the high pressure over North China, thereby preventing water vapor from going north. The contribution of SST is mainly at low latitudes and characterized by a significant cyclone anomaly over South China. The forecast models using predictor ASIC (PA), SST (PS), and the two together (PAS) are established by using data from 1980 to 2004. An independent forecast is made for the last 11 years (2005–2015). The correlation coefficient (COR) skills between the observed and cross-validation reforecast prin-cipal components (PC) of the PA, PS, and PAS models are 0.47, 0.66, and 0.76, respectively. These values indicate that SST is a ma-jor cause of Chinese summer extreme rainfall during 1980–2004. The COR skill of the PA model during the independent forecast period of 2004–2015 is 0.7, which is significantly higher than those of the PS and PAS models. Thus, the main factor influencing Chinese summer extreme rainfall in recent years has changed from low latitudes to high latitudes. The impact of ASI on Chinese summer extreme rainfall is becoming increasingly significant.Key words ASI; summer extreme rainfall; prediction1 IntroductionIn the Earth’s climate system, Arctic sea ice (ASI) is a major factor that has been extensively studied using ob-servation and climate models (Deser et al., 2000; Alex-ander et al., 2004; Magnusdottir et al., 2004). The loss of sea ice changes the radiation balance in the Arctic area (Schweiger et al., 2008). Further studies (Overland et al., 2008; Overland and Wang, 2010) have shown that sea ice changes have altered winds from a mostly zonal pattern to a meridional pattern in the last decade. This phenomenon allows additional heat to transfer poleward, resulting in both Arctic warming and mid-latitude cooling.Precious work has focused on the regional effects of sea ice loss over China (Niu et al., 2003). Abnormal sea ice along the North Pacific has obvious effects on both summer rainfall and temperature in China. In the years with large sea ice areas, rainfall increased over areas north of the Yangtze River and decreased in southern * Corresponding author. Tel: 0086-532-66786326E-mail: huangf@ China. By contrast, in the years with low sea ice, less rain fell in northern China and more in southern China. This study was concerned with relationships between the mon- thly–seasonal mean precipitation and ASI. The anomalies of ASI can also cause severe weather in China, such as disastrous freezing rain and heavy snow in central and southern China in January 2008 (Chen et al., 2013). Strong water-vapor transported from the Bay of Bengal and from the Pacific Ocean related to ASI anomalies in the fall of 2007 was considered one of the main causes of the snow-storm in 2008. Since 2008, several other severe weather events occurred in China, including the cold temperature anomalies in winter and spring from 2009 to 2010 and freezing rain over southern China from 2010 to 2011. Both of these events happened in winter and spring, right after the obvious anomalies of ASI in summer and fall. Statistical results (Wang and Zhou, 2005; Zhai et al., 2005; Liu et al., 2015) showed that the annual extreme precipitation events increase in east and northwest China and occur mainly in summer. Most of these studies attrib-uted the causes of this trend to the associated large-scale circulation over the Eurasian continent and the western Pacific and did not examine carefully its relationship withZHU et al . / J . Ocean Univ . China (Oceanic and Coastal Sea Research) 2019 18: 626-632627ASI. Therefore, this study focuses on the summer extreme rainfall and the effect of ASI on its changes.Extreme rainfall events have severe effects on society (Zhou et al., 2013; Lesk et al., 2016), and an accurate fore- cast of extreme rainfall over China will be helpful to pre-vent and manage disasters. Although the trend of extreme rainfall has been studied, its prediction is relatively unex-plored. Thus, another objective of this study is to identify the leading mode of summer extreme rainfall in China and determine the skills necessary for predicting it.In many former studies about the statistical forecast of summer rainfall over China (Xing et al., 2014; Yim et al., 2016; Li and Wang, 2017; Xing and Wang, 2017), subtro- pical sea surface temperature (SST) is used as the only pre- dictor from the sea. Zhao et al . (2004), Fang and Zeng (2008), and Guo et al. (2014) suggested that sea ice is closely connected with the summer monsoon rainfall in East Asia. These studies enlighten us to extract additional precursory signals for summer extreme rainfall in China from the sea. For this purpose, we build three statistical forecast models with ASIC and SST in selected regions and compare their forecast skill.2 Data and Method2.1 DataSeveral datasets are used in this study, including 1) daily precipitation records of 483 stations over China from the National Meteorological Information Center of China Me-teorological Administration; 2) monthly mean circulation data from National Centers for Environmental Prediction – Department of Energy (NCEP–DOE) Reanalysis prod-ucts; 3) monthly mean SST data from the European Cen-ter for Medium-Range Weather Forecasts Interim Re-analysis (ERA-Interim); and 4) Arctic sea ice concentra-tion (ASIC) data from National Snow and Ice Data Center (NSIDC). The period from 1979 to 2015 is chosen in this study.2.2 MethodFollowing Bell et al . (2004) and Liu et al . (2015), we define extreme rainfall events as those that exceed a 95% threshold percentile (top 5%) of daily precipitation (the amount of precipitation, unit: mm).Empirical orthogonal function (EOF) analysis is used in this study to reveal the leading modes of Chinese summer extreme rainfall. We focus on the seasonal means averaged for three summer (June–August, JJA) months. After EOF analysis, the North test (North et al., 1982) is conducted to examine whether the modes are inde-pendent of each other. The error range of eigenvalue λ is 121i j e n λ⎛⎫= ⎪⎝⎭, where n is the sample size. When the ad-jacent eigenvalue λj+1 satisfies the condition λj+1−λj≥ e j , the empirical orthogonal functions (EOF) corresponding to these two eigenvalues are considered valuable signals. Another purpose of this paper is to examine whetherASIC can be used as a predictor of summer extreme rain-fall in China, and a large-scale signal is studied. Predic-tors such as ASIC and SST used in this paper are defined in a large area, and the lead-lag correlation is considered (Lee et al., 2013). Thus, predictors are defined as follows:()(,)(,,)Pred t COR lon lat TF lon lat t ⎢⎥=⋅⎣⎦if (,)0.33(95%confidence level)COR lon lat ≥,where TF denotes the value of a predictor (ASIC, SST,and so on) at each grid at lead time t . COR is the correla-tion coefficient between a predictor and PC1 as a function of longitude and latitude, and square brackets indicate the areal mean over the selected regions. For ASIC, Pred (t ) is averaged over Arctic (180˚W–180˚E, 55˚N–80˚N), and it is also called ASICI (Arctic Sea ice concentration index) in this paper. Similarly, Pred (t ) of SST is called SST in-dex (SSTI).3 Statistic Linkage Between ASI and Chinese Summer Extreme RainfallEOF analysis of Chinese summer extreme rainfall is performed to extract the leading modes. The four leading EOF modes account for 10.6%, 7.6%, 6.7%, and 6.3% of the total rainfall variance. The north test shows that the first mode is independent, and the other three modes are not independent. This result reflects the complexity of extreme precipitation over China. Therefore, EOF1 of Chinese summer extreme rainfall and its linkage with ASIand SST are studied in this paper (Fig.1).Fig.1 (a) Spatial distribution of the leading EOF mode of Chinese summer extreme rainfall and (b) normalized prin-cipal components (PCs) of the leading mode. Stations with a solid circle in (a) indicate those with statistically signifi-cance at the 95% confidence level by EOF model check.The spatial distribution of EOF1 is characterized by a sharp contrast among South China, the Yangtze RiverZHU et al . / J . Ocean Univ . China (Oceanic and Coastal Sea Research) 2019 18: 626-632628 basin, and North China. More extreme rainfall appears in South and North China, whereas less is reported in the Yangtze River basin. For PC1, negative phases were fre-quent during 1979–1993 and 2009–2015, and positive phases were frequent during 1994–2008.The correlation map of PC1 with spring ASIC (MAM+ 0) is characterized by a positive correlation over Beaufort Sea and Bering Strait and mainly negative correlation along Eurasia and Greenland (Fig.2a). In the previous winter (DJF-1), the correlation map shows large areas of negative correlation along Eurasia. Meanwhile, negative correlation appears over Bering Strait (Fig.2b). The cor-relation maps of PC1 with changes in ASIC from previ-ous winter and autumn to current spring (MAM–DJF and MAM–SON denote ASIC of MAM minus that of previ-ous DJF and SON) are characterized by a positive corre-lation along Eurasia and negative correlation along Can-ada and west of Greenland (Figs.2c and 2d). Therefore, ASI melts may be an important cause of summer extreme rainfall in China.The correlation coefficients of ASICI and PC1 of four time periods (MAM+0, DJF-1, MAM–JF, and MAM– SON) are calculated using the method introduced in part 2 of this paper to further analyze the relationship between them. ASICI of all four time periods has a negative cor-relation coefficient with PC1. MAM and DJF exhibit the values −0.46 and −0.41, which are smaller than −0.32 (95% confidence level). Thus, MAM and DJF ASICI are more appropriate predictors than the other time periods. Considering that DJF ASICI as a predictor has a long lead time, it is chosen for the prediction of summer extreme rainfall in China.Fig.2 Correlation maps of PC1 of Chinese summer extreme rainfall with Arctic sea ice concentration: (a) MAM+0, (b) DJF-1, (c) MAM–DJF, and (d) MAM–SON. The black dotted regions show a correlation coefficient of 0.28 with statisti-cal significance at the 90% confidence level.The correlation between PC1 and JJA at 500 hPa geopo-tential height (Fig.3a) reflects the character of the Eura-sian wave train, with two significant negative center over the Urals and South China and two positive centers over Western Europe and North China. The western Pacific sub-tropical high is positioned more southward, and the con-tinental high is stronger than normal in this situation. Water vapor cannot be transported to the north of China, and most water vapor stays in southern China. As a result, less rain falls in northern China and more falls in southern China. The correlation between ASICI and JJA at 500 hPa geopotential height (Fig.3b) shows a similar distribution over Eurasian, with slight differences. The region of thestronger continental high pressure is wide, and a weak subtropical high over South China covers a small area. An important role that ASI plays in the appearance of EOF1 type summer extreme rainfall in China may be strengthen-ing the continental high pressure. The correlation between PC1 and SLP at 850 hPa wind (Fig.3c) demonstrates a sig-nificant cyclone over South China, which is beneficial to the emergence of heavy rainfall. A significant anti-cyclone occurs over South China Sea, and it helps transport water vapor to South China. The correlation between ASICI and SLP at 850 hPa wind (Fig.3d) indicates no significant cy-clone over South China, but a north wind is observed to come from high latitude. Another important role that ASIZHU et al . / J . Ocean Univ . China (Oceanic and Coastal Sea Research) 2019 18: 626-632629Fig.3 Correlation fields between PC1 and (a) 500 hPa geopotential height, (c) SLP (shading), 850 hPa wind (vectors), in June–August (JJA) during 1979–2015. (b) and (d) are similar to (a) and (c) but for ASICI. Dotted areas denote regions with correlation coefficients significant at the 95% confidence level.plays in the appearance of EOF1 type summer extreme rainfall in China is to provide cold air, which is also beneficial to the emergence of heavy rainfall by increas-ing the instability of air.4 Statistic Linkage Between SST and Chinese Summer Extreme RainfallFig.4 shows that the most significant positive correla-tion areas between SST and Chinese summer extreme rainfall are over the southwestern Indian Ocean (40˚E– 90˚E, 40˚S–0˚) during the time period of DJF to MAM and SON to MAM. Thus, the change in SST from autumn and winter of the previous year to spring in the tropical Indian Ocean may be an important cause of Chinese summer extreme rainfall. Using the zonal mean SST of this area (40˚E–90˚E, 40˚S–0˚), we build an SSTI of MAM+0, DJF-1, MAM–DJF, and MAM–SON. The tem-poral correlation coefficients between the four SSTI and PC1 are 0.41, 0.42, 0.49, and 0.57which are all at a 95% confidence level during 1979–2015. Thus, we choose SSTI of MAM-SON whose correlation coefficient with PC1 is highest as a predictor of Chinese summer extreme rainfall. The correlation between SSTI and JJA at 500 hPa geo-potential height (Fig.5a) shows a similar distribution to PC1, but the negative correlation area over the Urals is not significant at the 95% confidence level. In addition, an obvious cyclone (850 hPa wind) occurs over South China, with significant negative correlation on the SLP field. This cyclone can also be found on the correlation fieldbetween PC1 and 850 hPa wind but not on ASIC. These findings suggest that the influence of SST predictor to Chinese summer extreme rainfall is mainly concentrated in the low latitudes. The anomaly of SST from autumn before to spring over the southwestern Indian Ocean may indicate that more cyclones can cause heavy rain over South China in summer than in other seasons. On the 850 hPa wind field, a southwest wind belt from the western Indian Ocean to the South China Sea has a significant correlation with SSTI. This result implies that SST anom-aly in the Indian Ocean may contribute to the develop-ment of the southwest monsoon. As a result, more water vapor will be transferred to South China.5 Forecast Skill of ASICI and SSTITo investigate the predictability source of Chinese sum-mer extreme rainfall, we compare the forecast skills of PA, PS, and PAS. Using PA, PS, and PAS, PC1 prediction models are established through linear regression. The detailed definitions of the selected predictors for PC1 are presented in Sections 3 and 4. The cross-validation method (Michelson, 1987) is used to make a retrospective forecast for PC1. We train the models using data during 1980– 2004 and then apply the models to forecast the target years of 2005–2015. The observed PC is shown by a black line in Fig.6, whereas the corresponding cross-validation re- forecast PC and independent forecast PC are in blue and red lines. For PA, PS, and PAS, the CORs of cross-vali-dation reforecast PC and observed PC are 0.47, 0.66, andZHU et al . / J . Ocean Univ . China (Oceanic and Coastal Sea Research) 2019 18: 626-632630Fig.4 Correlation fields between PC1 and SST at (a) MAM+0, (b) DJF-1, (c) MAM–DJF, and (d) MAM–SON. Black dot-ted areas denote regions with correlation coefficients significant at the 95% confidence level and green dotted areas at the99% confidence level.Fig.5 Correlation fields between SSTI and (a) 500 hPa geopotential height and between SSTI and (b) SLP (shading) and 850 hPa wind (vectors) in June–August (JJA) during 1979–2015. Dotted areas denote regions with correlation coefficients significant at the 95% confidence level.0.76, respectively (Fig.6). The three correlation coefficients are all at the 95% significant level but at the 99% level for PS and PAS. Thus, PC1 can be regarded as predictable by ASIC and SST during 1980–2004, and SST is a more effective predictor than ASIC in this period. In Fig.6b, the model established by SST can better reflect the peak value of PC1, whereas the ASIC model is weaker than SST in this respect. However, in the independent forecast period of 2005–2015, the COR skill of the ASIC and SST models differs. The COR skill for the ASIC model is 0.7, which is at the 99% significant level and better than that for the period of 1980–2004. The COR skill for the SST model is 0.27, which is not significant at the 95% signifi-cant level. Thus, ASIC is a more effective predictor than SST for Chinese summer extreme rainfall in recent years. In Fig.6c, the model established by PAS has the best pre-diction effect during 1980–2004. Although SST plays a major role during this period, consideration of the com-bined effect of the two predictors can lead to better pre-diction effects. In the independent forecast period of 2005–2015, the COR skill of PAS is lower than that of PA. Our results provide further evidence that the ASI is the key factor for the forecast of Chinese summer extreme rainfall in recent decades. ASI is melting at an increasing rate in recent years (Comiso, 2012; Stroeve et al., 2012). In September 2007, the ASI reached its lowest areal ex-tent, which is about 40% below the long-term mean (Co-miso et al., 2008). Further research revealed that the on-going reductions of ASI may be impacting various as-pects of weather and climate in the Northern Hemisphere mid-latitudes. Our results are consistent with findings of previous studies.ZHU et al . / J . Ocean Univ . China (Oceanic and Coastal Sea Research) 2019 18: 626-632631Fig.6 Time series of PC1 obtained from observation (black line), cross-validated reforecast (blue line), and independent forecast (red line).6 ConclusionsThe present study investigates the predictability and prediction of Chinese summer extreme rainfall for the 37-year period of 1979–2015.The leading four major modes of Chinese summer ex-treme rainfall are identified by EOF, which explains 31% of the total variability. EOF1, which is independent, is studied in this paper. EOF1 reflects an extreme rainfall distribution in which more extreme rainfall appears in South and North China, whereas less occurs in the Yang-tze River Basin. EOF1 is closely related to the Eurasian wave train, which includes a positive anomaly over North China and negative anomaly over the Urals and South China. It is also associated with a significant anomalous cyclone on low-level wind field over South China.The lead-lag correlation between PC1 and ASIC from autumn of the previous year to spring of the current year indicates that the changes in ASIC at previous winter (DJF-1) and current spring (MAM+1) significantly impact Chinese summer extreme rainfall. In terms of PC1 and SST, the change in SST at the selected region over tropi-cal India Ocean from previous autumn to current spring (MAM–SON) is a key factor. The spatial correlation be-tween ASICI and summer atmospheric circulation indi-cates that the main contribution of Arctic Sea ice to Chi-nese summer extreme rainfall is at high latitudes, causing a significant positive anomaly over North China and nega-tive anomaly over the Urals on 500 hPa. For SST, the main contribution is mainly at low latitudes, causing a cyclone anomaly on 850 hPa wind field and negative anomaly on SLP.To assess the predictability of Chinese summer extreme rainfall, three prediction models are built using ASIC and SST as predictors. The cross-validated reforecast of the PA model for PC1 of Chinese summer extreme rainfall during the period of 1980–2004 achieves a significant forecast COR skill of 0.47, whereas that of the PS modelis higher at 0.66. These values suggest that the main sources of predictability of Chinese summer extreme rain-fall are rooted in tropical oceans for 1980–2004. Mean-while, the PAS model has the best COR skill of 0.76, which indicates that the predictability of Chinese summer extreme rainfall can yield a better result by considering the joint influence of ASI and SST during this period. However, the COR skill of the independent forecast of the ASIC model is 0.27 for 2005–2015, which is not signifi-cant, whereas the SST model achieves a significant COR skill of 0.70 for the same period. This obvious difference indicates that the effect of ASI on Chinese summer ex-treme rainfall is becoming more important and the pre-dictability signal of Chinese summer extreme rainfall is more from polar areas in the past decade.Anomalies of ASI may be a key factor to the weather and climate changes in China. In this study, we mainly focus on the predictability of Chinese summer extreme rainfall. The linkage between the ASI, SST, and Chinese summer extreme rainfall is not completely understood. Some studies (Wu et al., 2009a, 2009b) showed that the combined impacts of both spring ASI and Eurasian snow cover on the Eurasian wave train are thought to be the possible reason of the linkage between ASI and Chinese summer rainfall. The summer Arctic dipole anomaly may serve as the bridge linking the spring ASI and Chinese summer rainfall. In the future, additional studies are needed to confirm their relationships.AcknowledgementsAuthors thank NCEP and NCAR, the ECMWF for re-analysis data, the NSIDC for ASIC data, the National Meteorological Information Center of China for observa-tion datasets. This study is supported by the National Natural Science Foundation of China (No. 41575067), and the National Major Scientific Research of Global Change Research (No. 2015CB953904). We also appreci-ate two anonymous reviewers’ comments.ReferencesAlexander, M. A., Bhatt, U. S., Walsh, J. E., Timlin, M. S., Miller, J. S., and Scott, J. D., 2004. The atmospheric response to re-alistic Arctic sea ice anomalies in an AGCM during winter. Journal of Climate , 17: 890-905.Bell, J. L., Sloan, L. C., and Snyder, M. A., 2004. Regional changes in extreme climatic events: A future climate scenario. Journal of Climate , 17 (1): 81-87.Chen, H. X., Liu, N., and Zhang, Z. H., 2013. Severe winter weather as a response to the lowest Arctic sea-ice anomalies. Acta Oceanologica Sinica , 32 (10): 11-15.Comiso, J. C., 2012. Large decadal decline of the Arctic multi-year ice cover. Journal of Climate , 25 (4): 1176-1193.Comiso, J. C., Parkinson, C. L., Gersten, R., and Stock, L., 2008. Accelerated decline in the Arctic sea ice cover. Geophysical Research Letters , 35 (1): L01703.Deser, C., Walsh, J. E., and Timlin, M. S., 2000. Arctic sea ice variability in the context of recent atmospheric circulation trends. Journal of Climate , 13: 617-633.ZHU et al . / J . Ocean Univ . China (Oceanic and Coastal Sea Research) 2019 18: 626-632632 Fang, L., and Zeng, Q. C., 2008. Statistical prediction of East Asian summer monsoon rainfall based on SST and sea ice concentration. Journal of the Meteorological Society of Japan , 86 (1): 237-243.Guo, D., Gao, Y ., Bethke, I., Gong, D. Y ., Ola, M. J., and Wang, H. J., 2014. Mechanism on how the spring arctic sea ice im-pacts the East Asian summer monsoon. The Oretical and Ap-plied Climatology , 115 (1-2): 107-119.Lee, J. Y ., Lee, S. S., Wang, B., Ha, K. J., and Jhun, J. G ., 2013. Seasonal prediction and predictability of the Asian winter temperature variability. Climate Dynamics , 41 (3-4): 573-587. Lesk, C., Rowhani, P., and Ramankutty, N., 2016. Influence of extreme weather disasters on global crop production. Nature , 529: 84-87.Li, J., and Wang, B., 2017. Predictability of summer extreme precipitation days over eastern China. Climate Dynamics , 51: 1-12.Liu, R., Liu, S. C., Cicerone, R. J., Shiu, C. J., Li, J., Wang, J. L., and Zhang, Y . H., 2015. Trends of extreme precipitation in eastern China and their possible causes. Advances in Atmos-pheric Sciences , 32 (8): 1027-1037.Magnusdottir, G ., Deser, C., and Saravanan, R., 2004. The effects of North Atlantic SST and sea ice anomalies on the winter circulation in CCM3. Part I: Main features and storm track characteristics of the response. Journal of Climate , 17 (5): 857- 876.Michaelsen, J., 1987. Cross-validation in statistical climate fore- cast models. Journal of Applied Meteorology , 26 (11): 1589- 1600.Niu, T., Zhao, P., and Chen, L. X., 2003. Effects of the sea-ice along the North Pacific on summer rainfall in China. Acta Meteorological Sinica , 17 (1): 52-64.North, G . R., Bell, T. L., Cahalan, R. F., and Moeng, F. J., 1982. Sampling errors in the estimation of empirical orthogonal functions. Monthly Weather Review , 110 (7): 699-706.Overland, J. E., and Wang, M., 2010. Large-scale atmospheric circulation changes are associated with the recent loss of Arc-tic sea ice. Tellus Series A: Dynamic Meteorology & Oceanog-raphy , 62 (1): 1-9.Overland, J. E., Wang, M., and Salo, S., 2008. The recent Arctic warm period. Tellus Series A: Dynamic Meteorology & Ocean-ography , 60 (4): 589-597.Schweiger, A. J., Lindsay, R. W., Vavrus, S., and Francis, J. A., 2008. Relationships between Arctic sea ice and clouds during autumn. Journal of Climate , 21 (18): 4799-4810.Stroeve, J. C., Serreze, M. C., Holland, M. M., Kay, J. E., Ma-lanik, J., and Barrett, A. P., 2012. The Arctic’s rapidly shrink-ing sea ice cover: A research synthesis. Climatic Change , 110 (3-4): 1005-1027.Wang, Y ., and Zhou, L., 2005. Correction to ‘observed trends in extreme precipitation events in China during 1961–2001 and the associated changes in large-scale circulation’. Geophysi-cal Research Letters , 32 (17): 982.Wu, B., Zhang, R., and Wang, B., 2009. On the association be-tween spring Arctic sea ice concentration and Chinese sum-mer rainfall: A further study. Advances in Atmospheric Sci-ences , 26 (4): 666-678.Wu, B., Zhang, R. H., Wang, B., and D’Arrigo, R., 2009. On the association between spring Arctic sea ice concentration and Chinese summer rainfall. Geophysical Research Letters , 36: L09501.Xing, W., and Wang, B., 2017. Predictability and prediction of summer rainfall in the arid and semi-arid regions of China. Climate Dynamics , 49: 1-13.Xing, W., Wang, B., and Yim, S. Y ., 2014. Peak-summer East Asian rainfall predictability and prediction part I: Southeast Asia. Climate Dynamics , 47 (1-2): 1-13.Yim, S. Y ., Wang, B., Kim, H., and Yoo, H. D., 2016. Peak- summer East Asian rainfall predictability and prediction: Ex-tratropical East Asia. Climate Dynamics , 47 (1-2): 15-30.Zhai, P., Zhang, X., Wan, H., and Pan, X., 2005. Trends in total precipitation and frequency of daily precipitation extremes over China. Journal of Climate , 18 (7): 1096-1108.Zhao, P., Zhang, X., Zhou, X., Ikeda, M., and Yin, Y ., 2004. The sea ice extent anomaly in the north pacific and its impact on the East Asian summer monsoon rainfall. Journal of Climate , 17 (17): 3434-3447.Zhou, T., Song, F., Lin, R., and Chen, X., 2013. The 2012 north China floods: Explaining an extreme rainfall event in the con-text of a longer-term drying tendency. Bulletin of the Ameri-can Meteorological Society , 94: S49-S51.(Edited by Chen Wenwen)。

青藏高原东南边缘地壳和上地幔速度结构体波、面波和重力联合成像研究

青藏高原东南边缘地壳和上地幔速度结构体波、面波和重力联合成像研究摘要为了探讨汶川地震和芦山地震之间余震空白区的速度结构特征和存在原因，探讨青藏高原东南边缘大地震与速度分布的关系和该地区大地震的发震机制以及约束青藏高原不同的变形模型，我们分别进行了青藏高原东南边缘体波和面波的联合反演和体波、面波和重力数据的联合反演，得到了该地区地壳和上地幔新的三维Vp和Vs模型。

体波数据是2001-2004年，2008年5-8月和2013年4-5月由青藏高原东南边缘102个台站记录的7190个地震事件。

面波数据是从青藏高原东南边缘由298个宽频地震仪组成的台间距大约为15km的密集台阵记录的背景噪声中提取的瑞雷波相速度频散曲线，周期为4-40s。

重力数据是从Bureau Gravimétrique International提供的全球重力模型EGM2008提取的布格重力异常。

体波和面波联合反演的速度结构在浅部与当地地质相吻合。

四川盆地的低速对应厚的沉积层，龙门山块体的高速对应中上三叠复理石。

在10km深度，速度结构具有很强的不均匀性。

四川盆地从西北到东南分别为低速，高速和低速，分别对应四川盆地西北凹陷，中部上升和东南凹陷。

龙门山断层从东北到西南分布有三个高速异常体，分别对应雪山高原的变质岩，彭灌杂岩和宝兴-康定杂岩。

这三个高速体之间为两个低速区（LV1和LV2）。

LV1对应汶川地震同震位移小和余震分布少的地区，LV2为汶川地震和芦山地震之间的余震空白区。

这两个低速区的物质机械强度可能弱，应力难以积累，大地震难以发生，因此低速区可能是大地震破裂的障碍区。

在青藏高原东南边缘大多数大地震发生在高低速异常的分界线上。

我们推测高速区容易积累应力，但是不易破裂，低速地区物质强度低，不易于积累应力。

高低速异常的边界同时具有高低速异常体各自的特点，既可以积累应力又易于破裂，因此高低速异常的边界可能是大地震成核的有利位置。

马里亚纳南部弧内坡橄榄岩中的角闪石成分对于弧下地幔交代流体的指示

流体组分的讨论。本文将着重分析不同成分的角闪石的成因，以此探讨俯冲板片释放的流体的化学并
特点。
其晶格中含有ＯＨ而被认为是流体与橄榄岩发生交代反应的典型产物，弧下地幔橄榄岩中的角闪对
地幔楔橄榄岩的交代作用还知之甚少。角闪石因为
镁、和大量微量元素的迁移［。从已有的研究钠３］来看，里亚纳弧前橄榄岩中的角闪石的种类多样，马有透闪石、角闪石以及浅闪石等＿３２，于不同镁１－￣对 ’ 种类的角闪石的成因探讨有限，制约了对于俯冲也
２地质概况
马里亚纳俯冲带是典型的洋内俯冲带，它是在
约４５Ｍａ左右太平洋板块漂移方向由北转为北北西的大背景下，已有的长转换断层的基础上发展在而来ｌ。由于俯冲洋壳的年龄老、＿８］密度大＿，ｇ同时太］
究发展规划项目（０７Ｂ１７３１的资助。２０Ｃ４１００）
作者简介：）￣
（９３）男，西省晋城市人，理研究员，究方向为海底资源与成矿作用。Ｅｍａ：ｕｔｒ５９＠１３ｃｏｍ１８－，山助研－ｉｌｓｅ１９１６ｌ
第３３卷
第５期
海
洋
学
报
Ｖｏ．３。Ｎｏ５１３．

弹性波成像方法面波勘探技术

2. 检波器：目前国内外生产的检波器类型较多，面波测试时，可从固有频率为4.5、8、10、15、28 等检波器中选择使用，瞬态面波一般使用固有频率较低的检波器
• 检波器接收到的基本是瑞雷波的垂直分量。瞬态冲击激发的面波可以看作许多单频谐振的叠加，因而记录到的波形也是谐波叠加的结果，呈脉冲型的面波。
面波的衰减纵波横波的波前面相对激发点呈球面扩散面波的波前面呈圆柱面扩散所以能量密度衰减较沿深度方向衰减快仅存在于一个波长深度内沿水平方向的能量密度随传播距离按r1衰减比球面扩散的体波能量密度按r2衰减的规律慢得多另外研究证实在弹性半空间表面上通过园形基础加一个垂向振动力能量从震源向下辐射约有23的能量转化为面波而仅有13能量是由体波携带的
2 信号处理、频散曲线的建立与反演
面波频散曲线是对地层速度结构分层的基础。若对每个面波测试点的频散曲线进行分层和层速度计算，确定各层的厚度，计算各层的横波传播速度，并对获得结果进行反演拟合处理，即可达到定量解释的效果；同时对同一条测线上的相邻点在垂直方向上相同的层速度连接起来，用一系列颜色代表逐渐递增的速度，就可得到层速度彩色剖面图
六、面波数据采集
1. Fixed spread (Short line)
2. Fixed Spread of Moving Style relying only on Takeout Cables (for Long Line)
3.End-on-spread (for Long Line) applying CDP switch
瞬态面波法：
利用瞬态冲击力作震源激发面波，地表在脉冲荷载作用下，产生波动。
在离震源稍远处，用检波器记录面波的垂直分量。
对面波信号作频谱分析和处理，获取频散曲线。

瑞雷波Rayleigh Wave

Chapter 3Rayleigh Waves3.1OverviewWaves that propagate in a medium can be roughly divided into two main categories: body waves and surface waves. Surface waves are generated only in presence of a free boundary and they can be essentially of two types: Love waves and Rayleigh waves. Love waves can exist only in presence of a soft superficial layer over a stiffer halfspace and they are produced by energy trapping in the softer layer for multiple reflections. Rayleigh waves are always generated when a free surface exists in a continuous body.John Strutt Lord of Rayleigh firstly introduced them as solution of the free vibration problem for an elastic halfspace in 1885 (“On waves propagated along the plane surface of an elastic solid”). In the last sentences of the above paper, he anticipated the importance that such kind of wave could have in earthquake tremor transmission. Indeed the introduction of surface waves was preceded by some seismic observations that couldn’t be explained using only body wave theory, which was well known at that time. First of all the nature of the major tremor was not clear, because the first arrivals were a couple of minor tremors corresponding to P and S waves respectively. The greater amount of energy associated to this late tremor if compared to that of body wave was a strong evidence of less attenuation passing through the same medium and this could be explained only assuming that this further kind of wave was essentially confined to the surface (Graff 1975).Another main contribution regarding the forced vibrations was successively28Multistation methods for geotechnical characterization using surface waves S.Foti given by Horace Lamb (“On the propagation of tremors over the surface of an elastic solid”, 1904), who solved the problem of a point harmonic force acting on the ground surface. He also proposed the solution for the case of a general pulse,by using the Fourier synthesis concept.Usefulness of surface waves for characterization problems has been soon clear due to some important features and especially to the possibility of detecting them from the surface of a solid, with strong implications on non-invasive techniques development (Viktorov 1967).In this chapter an overview will be given about specific properties of Rayleigh waves, with special aim at soil characterization purposes, leaving more comprehensive treatment to specific references.Also some numerical simulations and some experimental data will be presented in the view of clarifying some important aspects related to Rayleigh waves propagation and to its modelling.3.2 Homogeneous halfspace3.2.1 Linear elastic mediumIf the free boundary condition is imposed on the general equations for wave propagation in a linear elastic homogeneous medium, the solution for surface Rayleigh wave can be deduced from the P-SV components of the wave. It is important to note that a SH wave propagating on a free boundary can exist only under restrictive layering condition (and in that case it is usually called Love wave)and hence it cannot exist for the homogeneous halfspace.The Navier’s equations for dynamical equilibrium in vector formulation can be expressed as:u f u u !!44((*'+5+&55+2)((3.1)where u is the particle displacement vector, 4 the medium density, * and ( the Lamè’s constants and f the body forces. Neglecting the latter contribution, the free vibration problem is addressed.The solution can be searched using Helmholtz decomposition and assuming an exponential form (Richart et Al. 1970). The motivation for assuming the exponential form is that by definition a surface wave must decay quickly with depth.Chapter 3Rayleigh Waves 29Imposing the boundary conditions of null stress at the free surface:0ó'(3.2)the surface wave solution can be found. In particular for the case of plane strain,discarding the solutions that give infinite amplitude at infinite depth, a solution (Rayleigh wave) can be found only if the following characteristic equation is satisfied by the velocity of propagation of the surface wave:0)1(16)1624(822246'-&+&-+-##K K K (3.3)where K and G are the following ratios between velocities of longitudinal (P),distortional (S) and Rayleigh (R) waves:S RV V K '(3.4)P SV V '#(3.5)This equation is a cubic on 2K and its roots are a function of Poisson Ratio ,since, as shown in Paragraph 2.3.1, )1(2212,,#--'. It can be shown (Viktorov 1967) that for real media (5.00P P :) only one real and acceptable (i.e. in the range 0 to 1) solution exists. The relationship between velocities of propagation of the different waves as a function of Poisson Ratio is reported in Figure 3.1.An approximate solution of the characteristic equation (3.3) has been suggest by Viktorov (1967):::++'112.187.0K (3.6)From Figure 3.1, it is evident that the difference between shear wave velocity and Rayleigh wave velocity is very limited, being the latter slightly smaller than the former. In particular the exact range of variation is given by:96.087.0P P S R V V (3.7)Note that there is no dependence of Rayleigh wave velocity on frequency, i.e.a homogenous linear elastic medium is characterised by a unique value of Rayleigh wave velocity.30Multistation methods for geotechnical characterization using surface waves S.FotiFigure 3.1 Relation between Poisson’s ratio and velocity of propagation of compression (P), shear (S) and Rayleigh (R) waves in a linear elastic homogeneous halfspace (from Richart 1962)It is important to remark that since the solution has been obtained using Helmholtz decomposition, the surface wave can be seen as the superposition of two separate components: one longitudinal and the other transverse. They propagate along the surface with the same velocity but they have different exponential laws of attenuation with depth. Obviously the wave fields are such that the superposition of the two gives a null total stress on the boundary of the halfspace.Figure 3.2 Particle motion on the surface during the passage of a Rayleigh waves in an elastic homogeneous halfspaceChapter 3Rayleigh Waves31 As far as the displacement fields are concerned, they can be computed introducing the solution of the characteristic equation into the respective formulations. The resulting horizontal and vertical components of motion are out of phase of exactly 90° one with the other, with the vertical component bigger in amplitude than the horizontal one, hence the resulting particle motion is an ellipse. On the ground surface the ellipse is retrograde (e.g. counter-clockwise if the motion is propagating from left to right as shown in Figure 3.2), but going into depth the ellipse is reversed at a depth equal to about 1/2@ of the wavelength.Another important remark is that being the decrease with depth exponential, the particle motion amplitude becomes rapidly negligible with depth. For this reason it can be assessed that the wave propagation affects a confined superficial zone (see Figure 3.3), hence it is not influenced by mechanical characteristics of layers deeper than about a wavelength.Figure 3.3 Amplitude ratio vs. dimensionless depth for Rayleigh wave in a homogenous halfspace (from Richart et Al. 1970)32Multistation methods for geotechnical characterization using surface waves S.FotiThe solution for a line or point source acting on the ground surface can be found in the Lamb’s paper that has been cited above. In this regard it is important to remark that, due to the axial-symmetry of the problem, the disturbance spreads away in the form of an annular wave field. The reduced geometrical attenuation of surface waves can be directly associated to this property.Also Lord Rayleigh, although he didn’t solve the case of a point source, had a similar intuition about surface waves: "Diverging in two dimensions only, they must acquire at a great distance from the source a continually increasing preponderance" (concluding remarks of the above cited paper).The geometric spreading factor, i.e. the factor according to which the waves attenuate as they go away from the source, can be estimate with the following physical considerations about the wave fronts.Considering a buried point source in an infinite medium, the released energy spreads over a spherical surface and hence its attenuation is proportional to the square of distance from the source. Since the energy is proportional to the square of displacements, the latter ones attenuate proportionally to distance. Analogously since Rayleigh waves, that are generated by a point source acting on the ground surface, propagate with a cylindrical wave-front, their energy attenuation must be proportional to distance and displacement attenuation to the square root of distance.Concerning the geometrical attenuation of longitudinal and shear waves along the free surface, it is not possible an analogy to previous cases, but it can be shown that because of leaking of energy into the free space the displacement attenuation goes with the square of distance (Richart et al. 1970). In summary for a linear elastic halfspace a simple power law of the following type can express the radiation damping consequences on waves amplitude:Q Q R Q Q S T 'waves Rayleigh for 21solid the into waves body for 1surface the on waves shear and al longitudin for 2with 1n r n(3.8)where r is the distance from the point source.Back to Lamb’s work, the displacements at great distance r from a vertical harmonic point force t i z e F 3& can be expressed as:Chapter 3Rayleigh Waves 33A B C D E F --&&'4@3kr t i z z z e r b F u (3.9)A B C D E F +-&&'4@3kr t i r z r e r b F u (3.10)where z u and r u are the vertical and radial displacements, z b and r b are functions of the mechanical parameters of the medium and k is the wavenumber that is defined by the following relation:R V k 3'(3.11)The two displacements are out of phase of 90° and hence the particles describe an elliptical path, as it was predicted by the solution of the homogeneous problem related to free vibration.Figure 3.4 Complete wavefield predicted by Lamb (1904) for a surface point source on an elastic halfspace (a) horizontal radial motion; (b) vertical motion; (c) particle path of Rayleigh waves.34Multistation methods for geotechnical characterization using surface waves S.FotiFigure 3.5 Harmonic vertical point source acting on the surface of a homogenous,isotropic, linear elastic halfspace: (a) Complete displacements wave field; (b) Partition of energy between different types of waves (from Woods 1968).The position of a given characteristic point of the wave (such for example a peak or a trough) is described by constant values of the phase:/0const kr t '-3(3.12)thus with some manipulation and recalling Equation (3.11) it is clear the reason why R V is often denoted as Rayleigh wave phase velocity.Considering a circular footing vibrating harmonically at low frequency over a homogeneous isotropic linear elastic halfspace, Miller and Pursey (1955) showed that 2/3 of the total input energy goes into Rayleigh waves and the left fraction isChapter 3Rayleigh Waves 35divided between body waves (see Figure 3.5b). Adding this information to the above considerations about geometrical attenuation, the conclusion is that at a certain distance from the source the wavefield is essentially dominated by the Rayleigh waves. This is essentially the same conclusion reached by Lamb (1904),who divided the wave contributions in two minor tremors (P and S) and a major tremor (R) (Figure 3.4).All the important features of the complete wave-field generated by a low frequency harmonic point source are summarised in Figure 3.5.3.2.2 Linear viscoelastic mediumAs seen in Chapter 2, also at very low strain levels soil behaviour can’t be considered elastic, indeed cycles of loading and unloading show energy dissipation.Recalling the actual nature of soil, it is intuitive that dissipation is essentially due to the friction between particles and the motion of the pore fluid, and hence it occurs also for very small strains, when the soil is far from the plasticity conditions.To account for dissipation, an equivalent linear viscoelastic model can be assumed at small strains. In this regard the correspondence principle can be used to extend the result obtained in the case of a linear elastic medium. According to it,the velocity of propagation of seismic waves can be substituted by a complex valued velocity that accounts for the attenuation of such waves. Adopting this principle Viktorov (1967) showed that the attenuation of surface waves in a homogeneous linear viscoelastic medium is governed primarily by the shear wave attenuation factor. In particular he found that the Rayleigh wave attenuation R G could be expressed as a linear combination of the longitudinal wave attenuation P G and the shear wave attenuation S G , according to the expression:/0S P R A A G G G &-+&'1(3.13)where is A a quantity depending only on the Poisson Ratio. Since A is always smaller than 5.0, the shear wave attenuation is prevalent in determining the Rayleigh wave attenuation. Moreover for Poisson Ratio values higher than 0.2, A is less than 2.0 (see Figure 3.6).The wave field generated by a vertical harmonic point source acting on the ground surface can be obtained applying the correspondence principle to the Lamb’s solution. For example substituting a complex wavenumber in (3.9) it is possible to evaluate the vertical displacements as:36Multistation methods for geotechnical characterization using surface waves S.FotiA B C D E F --&&'4**@3r k t i zz z e r b F u (3.14)where obviously also the quantity *zb is changed since it is dependent on the mechanical parameters, that now are those of the viscoelastic medium.The complex wavenumber is defined as:/03G 33G i V i k k R -'-')(*(3.15)where /03G is the material attenuation of surface waves and R V is now frequency dependent because of material dispersion. With some manipulations of Equation (3.14) the phase and the amplitude of the displacements can be separated as follows:A B C D E F ---&&&'4*@3G kr t i r zz z e e r b F u (3.16)and in this formulation the exponential effects due to the material attenuation is evident. Note also that the quantity re rG - represents the combined effect of material and geometrical attenuation as the wave spreads out from the source.Figure 3.6 Body waves attenuation participation factors vs. Poisson ratio (Viktorov 1967)Chapter 3Rayleigh Waves 373.3 Vertically heterogeneous media3.3.1 Linear elastic mediumFor heterogeneous and anisotropic media the mathematical formulation of Rayleigh waves becomes very complex and there can be cases of anisotropic media where they do not exist at all. However in the case of transverse isotropic medium with the free surface parallel to the isotropy plane (common situation for soil systems) Rayleigh waves exist and the analogous of the Lamb solution can be found (Butchwald 1961).As far as heterogeneity is concerned, when the mechanical properties of the medium are assumed to be dependent only on depth z , the formal expression of the Navier’s equations, neglecting body force, is:u u u e .u e u .u !!4(*((*'A B C D EF >>&+757+5+5+55+z dz d dz d z z 2)(2(3.17)where z e is the base vector for the direction perpendicular to the free surface.Lai (1998) has showed that introducing in (3.17) the condition of plane strain (that causes no loss of generality) and assuming the classical exponential form for the solution, the final solution is given by a linear differential eigenvalue problem.Assuming the usual boundary condition of null stress at the surface, the eigenvalues )(3k can be found as the values that makes equal to zero the equivalent of the Rayleigh characteristic equation, that in this case can only be written in implicit form (Lai 1998):/0/0/0890,,,,R '34(*j k z z z F (3.18)It is noteworthy to remark some important features of this equation. First of all the dependence on the frequency means that also the relative solution will be frequency dependant and hence the resulting wave field is dispersive, meaning that its phase velocity will be a function of frequency. This dispersion is related to the geometrical variations of Lamé’s parameters and density with depth and hence it is often called geometric dispersion. The equation (3.18) itself is often named dispersion equation.For a given frequency the solutions of the dispersion equation are several while in the case of the homogeneous halfspace there was only one admissible solution of the characteristic equation. This means that many modes of propagation of the Rayleigh wave exist and the solution of the forced vibration case must account for them with a process of mode superposition.38Multistation methods for geotechnical characterization using surface waves S.Foti Substituting each one of the eigenvalues (wavenumbers) in the eigenproblem formulation, four eigenfunctions can be retrieved. They correspond to the two displacements and the two stresses associated to that particular wave propagation mode.The existence of several mode of propagation can be explained physically through the concept of constructive interference (Lai 1998).3.3.1.1Mathematical formulations for layered mediaIn the formulation of the dispersion equation (3.18) there was no explicit reference to any law of variation of the mechanical properties with depth. The problem can be solved once a law of variation is specified. In general it is not possible to solve the problem analytically and a numerical solution is needed.In this respect one classical assumption is that of a stratified medium with homogeneous linear elastic layers. This modelling procedure, that has been established for seismological purposes, assume a stack of layers, each one characterised by its thickness, elastic parameters and density (Figure 3.7). Obviously a price is paid in terms of generality but the eigenvalue problem can be established using a matrix formulation for a single layer and then building the global matrix, which governs the problem.Figure 3.7 Stack of homogeneous isotropic elastic layers Many version of this general procedure, also known as propagator-matrix methods (Kennett 1983), have been formulated, differing in the principles on which the single layer matrix formulation is based and consequently in the assembling process.Chapter 3Rayleigh Waves 39The oldest and probably the most famous method is the Transfer-Matrix method, originally proposed by Thomson (1950) and successively modified by Haskell (1953).The Stiffness-Matrix method proposed by Kausel and Roesset (1981) is essentially a reformulation of the Transfer-Matrix method, having the advantage of a simplified procedure for the assembly of the global matrix, according to the classical scheme of structural analysis.The third possibility is given by the construction of reflection and transmission matrices, which account for the partition of energy as the wave is propagating. The wave field is then given by the constructive interference of waves travelling from a layer to another (Kennett 1974, 1979; Kerry 1981).Once the dispersion equation has been constructed using one of the above methods, the successive and very computationally intensive step is the use of a root searching technique to obtain the eigenvalues of the problem. Great attention must be paid in this process because of the behaviour of the dispersion function. Indeed some solution searching techniques can easily fail due to the strong oscillations of the dispersion function especially at high frequencies (Hisada 1994, 1995). In this respect since these methods are borrowed from seismology, the frequencies involved in the soil characterization methods have to be considered high.Recalling the starting point of the above considerations (Equation (3.17)) the eigenvalues, and hence the correspondent eigenfunctions, that have been computed are the solution of the homogeneous problem, i.e. in absence of an external source.The obtained modes constitute the solution of the free Rayleigh oscillations of the considered medium.If a source exists, the correspondent inhomogeneous problem must be solved.In this case a term that represents the external force is included in Equation (3.17).The solution comes from a mode superposition process. Sometimes this problem is addressed as the three dimensional solution because waves spread out from the source following a 3D axial-symmetric path, whereas the free modes represent plane waves and hence are addressed as the solution of the 2D problem.For our purposes it is relevant the case of a point source acting on the ground surface. Lai (1998) has given an interesting solution for the case of a harmonic point load t i z e F 3&. According to its formulation, if body wave components are neglected (i.e. in far field conditions) the displacements induced by the load are given by:89),,(),,(),,(3U 3V V V 33z r t i z e z r F z r u -&&&'G (3.19)where V stands for the generic component either vertical or radial, ),,(3V z r G is40Multistation methods for geotechnical characterization using surface waves S.Foti the Rayleigh geometrical spreading function, that models the geometric attenuation in layered medium, and ),,(3U V z r is a composite phase function.An interesting comparison can be made between Equation (3.19) and its equivalent for a homogeneous halfspace (Eq. (3.9) and (3.10)), in which case the mode of propagation was only one. First of all the geometric attenuation for the homogeneous halfspace is much simpler. On the other side phase velocity is coincident with that of the only one mode of propagation, while in the case of the layered medium also the phase velocity comes from mode superposition and for this reason is often indicated as effective or apparent phase velocity.In analogy to Equation (3.12), the position of a given characteristic point of the harmonic wave (such for example a peak or a trough) is described by constant values of the phase:/0constz r t '-),,(3U 3V (3.20)hence differentiating with respect to time, under the hypothesis that the function ),,(3U V z r be smooth enough, it is possible to obtain the effective phase velocity RV ˆ(Lai 1998):r z r z r V R >>'),,(),,(ˆ3U 33V (3.21)It is very important to note that since the effective Rayleigh velocity is a function not only of frequency but also of the distance from the source, it is a local quantity (see Lai 1998 for a comprehensive discussion on this topic).3.3.1.2 Physical remarksSome physical aspects are implicitly included in the mathematical formulations of vertically heterogeneous media described above. It can be useful trying to describe them in a more phenomenological way.First of all the geometrical dispersion, i.e. the dependence of Rayleigh phase velocity on frequency can be easily explained recalling the characteristics of shallowness of this waves. As exposed in Paragraph 3.2.1 for a homogeneous linear elastic halfspace the exponential decay of particle motion with depth is such that the portion of the medium that is affected by the wave propagation is equal to about one wavelength. Since the wavelength R * is related to the frequency f by the following relation:Chapter 3Rayleigh Waves 41f V RR '*(3.22)it is clear that low frequency waves will penetrate more into the ground surface.Hence in the case of a vertically heterogeneous medium, surface waves at different frequency will involve in their propagation different layers and consequently the phase velocity will be related to a combination of their mechanical properties.Consequently the surface waves velocity will be a function of frequency. The above concept is summarised in Figure 3.8, where the vertical displacements wave field in depth at two different frequencies is presented for a layered medium.Figure 3.8 Geometrical dispersion in layered media (from Rix 1988)It is important to remark that the shape of the dispersion curve (Rayleigh phase velocity vs. frequency or wavelength) is strongly related to the variation of stiffness with depth. Usually a distinction is made between a layered system for which the stiffness is monotonically increasing with depth and another one in which there is the presence of stiffer layers over softer ones. The first case is indicated as normally dispersive profile, the latter one as inversely dispersive profile. An example is presented in Figure 3.9, where the shape of the dispersion curve is presented in the phase velocity-wavelength plane. This representation is often used since for the aforementioned reasons it gives a clear picture of the variation of stiffness with depth.Obviously in real media the alternation of stiff and soft layers can be much42Multistation methods for geotechnical characterization using surface waves S.Foti more complex if compared to the above cases, still Figure 3.8 gives an idea of the relation existing between the stiffness profile and the dispersion curve.Figure 3.9 Examples of non dispersive (homogeneous halfspace), normally dispersive and inversely dispersive profiles (from Rix 1988)Chapter 3Rayleigh Waves43 Another important feature of surface waves propagation in layered media is the existence of several modes of propagation. This can be explained physically by the presence of constructive interference between curved ray-paths for continuously varying heterogeneous media and between transmitted and reflected waves for layered media (Achenbach 1984). The presence of several modes of propagation makes the forced case very complex since the active energy that the source introduces into the medium is propagating away with a superposition of the different modes. It is not possible to say a priori which mode dominates and in general there is the transition from the predominance of a mode to that of another one for different frequencies (Gukunski e Woods 1992). For these reasons the case of an impulsive source is particularly complex. Nevertheless usually, for normally dispersive profiles and in absence of strong stiffness jumps, the fundamental mode of propagation dominates the wavefield. In such cases the effective phase velocity practically coincides with the phase velocity of the fundamental mode. Hence resolving only the eigenvalue problem, with no need to account for mode superposition is sufficient for the construction of a good approximation of the effective dispersion curve.Moreover also geometrical attenuation becomes very complex in the case of layered media and a geometric spreading function need to be introduced (see Equation (3.19)). Regarding this aspect (that is very important when also displacements amplitudes are of interest), if the above conditions for the predominance of the first mode of propagation are satisfied, further complications1for can be avoided by taking the usual factor of homogeneous halfspace r geometrical attenuation.Another important note can be made about the path described by particle motion on the ground surface. For the homogeneous halfspace vertical and horizontal components are 90° out of phase in such a way that as the wave is propagating the particle motion describes a retrograde ellipse. In the case of a layered medium the path is always elliptical but not necessarily retrograde. Moreover in presence of dissipative phenomena (that are likely to occur in soils) the phase difference between vertical and horizontal displacements can be different from 90° and the axes of the ellipse are not necessarily vertical and horizontal respectively (Haskell 1953).An important consequence of surface wave dispersive behaviour in layered media is the existence of a group velocity. Up to now, when talking about velocity of propagation of surface waves, we used the term phase velocity, that is the velocity of a wave front (locus of constant phase points), such as a peak or a trough. For a dispersive medium, this is not the same as the velocity of a pulse of energy, indeed the latter can be seen (Fourier analysis) as composed of several。

弹性波层析成像研究及工程应用

弹性波层析成像研究及工程应用弹性波层析成像（elastic wave tomography）是一种利用地面或井下布设的传感器获取地下弹性波数据，进而识别和定量化地下介质中波速和波阻抗分布的技术。

弹性波层析成像在地震勘探、地下水资源调查、地质灾害监测和地下工程设计等领域有着广泛的应用前景。

弹性波层析成像的研究基于弹性波理论，其中最重要的是波动方程（弹性波方程）的数值求解。

常见的数值方法包括有限差分法（Finite Difference Method, FDM）、有限元法（Finite Element Method, FEM）和伴随状态法（Adjoint State Method）等，这些方法能够有效地模拟地下弹性波传播的过程。

弹性波层析成像的工程应用主要包括地震勘探和地下工程设计。

地震勘探是利用地震波在地下不同介质中传播的特点来勘探地下结构的一种方法。

弹性波层析成像作为地震勘探的一种新技术，能够对地下构造进行高分辨率成像，从而提供地质勘探、矿产资源勘查、油气田勘探等方面的重要信息。

利用弹性波层析成像能够更准确地识别天然气、油藏、水库等地下目标的位置和分布，为油气勘探、水资源调查和自然灾害预测等提供了有力的工具。

另外，弹性波层析成像在地下工程设计中也具有重要的应用价值。

在地铁、隧道、桥梁和大型建筑物等工程设计中，需要对地下结构进行全面的了解，以确保工程的安全和稳定性。

利用弹性波层析成像可以对地下介质的构造进行准确的成像，包括地层的厚度、地质体的形态和分布等信息，为工程设计提供可靠的基础数据。

此外，弹性波层析成像还可以用于地下水资源调查、土壤侵蚀监测和地质灾害监测等方面，为城市规划和环境保护提供有力的支持。

与传统的地震勘探和地下工程方法相比，弹性波层析成像具有以下几个优势。

首先，弹性波层析成像可以提供更高的空间分辨率和准确性，能够更好地识别地下构造的细节和变化。

其次，弹性波层析成像可以同时获得地震波在地下材料中传播的速度和波阻抗信息，有助于对地下介质的物理特性进行定量化研究。

Opitcal Waves in Layered Media》(层状介质中的光波

《Opitcal Waves in Layered Media》简介一、出版情况《层状介质中的光波》（Optical Waves in Layered Media）是1998年由美国John Wiley & Sons 公司出版的，本书为2005年再版，全书406页。

二、作者情况叶伯琦(Pochi Yeh)目前是美国加州大学圣塔芭芭拉分校（University of California at Santa Barbara）电机电脑系教授与交大讲座教授（合聘）。

他1967年至1971年于国立台湾大学攻读物理系学士学位，1973至1975于美国加州理工学院物理系攻读硕士学位，1973至1977年于美国加州理工学院攻读物理系博士。

毕业后至1990年在美国洛克威尔国际科学中心光资讯部门任执行经理并在1985年至1990年任美国洛克威尔国际科学中心首席科学家。

1987年至今任台湾国立交通大学光电工程研究所兼任教授。

1990年被聘为加州大学圣塔芭芭拉分校电机电脑系教授。

曾荣誉美国光学学会会士（Optical Society of America Fellow）、电子电机工程学会会士（(IEEE Fellow）、洛克威尔科学中心达芬奇杰出工程师奖（Leonardo da Vinci Award, Engineering of the Year 1985）、国际光学工程学会金氏奖（Rudolf Kingslake Medal and Prize）等。

除本书外主要著作有晶体中的光波（Optical Waves in Crystals, Wiley l984）；非线性光折射简介（Introduction to Photorefractive Nonlinear Optics，Wiley l993）；液晶显示光学（Optics Of Liquid Crystal Displays, Wiley l999）；光子学：现代通信中的光电子学（Photonics: Optical electronics for modern communications，Oxford University Press 2006）。

关于创新的传感技术可以改善温室气体之浅析

关于创新的传感技术可以改善温室气体之浅析
一个国际研究团队使用一种称为鬼影成像的非常规成像技术来对气体分子进行光谱测量。

芬兰坦佩雷理工大学，东芬兰大学和法国勃艮第弗朗什——孔泰大学的科学家采用的新方法适用于各种波长，可以改善甲烷等大气温室气体的测量。

在光学学会（OSA）期刊Optics Letters上，研究人员报告了他们扩展鬼影成像技术的方法，以产生非常有效的光谱测量，揭示有关气体分子化学组成的信息。

他们通过使用具有超连续光源的重影来实现这一点，以捕获通过样本传输的波长相关光，并证明该技术可以测量具有亚纳米分辨率的温室气体甲烷的光谱特征。

“监测大气温室气体，如甲烷，二氧化碳，氧化亚氮和臭氧，对于评估这些气体的变化水平与气候变化的关系非常重要，”坦佩雷理工大学研究小组成员Caroline Amiot说。

“在某些特定情况下，我们的方法可以更灵敏地检测温室气体，提供有关这些重要化合物的更准确信息。

”。

斜长角闪岩

Contrib Mineral Petrol (2014) 168:1060DOI 10.1007/s00410-014-1060-0Rare earth element–SiO 2 systematics of island arc crustal amphibolite migmatites from the Asago body of the Yakuno Ophiolite, Japan: a field evaluation of some model predictionsXiaofei Pu · James G. Brophy · Tatsuki TsujimoriReceived: 25 April 2014 / Accepted: 21 August 2014 / Published online: 9 September 2014 © Springer-Verlag Berlin Heidelberg 2014that of the host rock. Assuming an initial source amphibolite that is slightly LREE-enriched relative to the host amphibo-lites, the observed REE abundances in the felsic veins fully support all theoretical predictions.Keywords Amphibolite · Migmatite · Rare earth elements · Partial melting · Silicic magmaIntroductionThe generation of silicic magmas in intra-oceanic arc envi-ronments is a subject that has received a lot of attention. Though many possible origins have been suggested, the two most commonly invoked processes for generating such magmas are extended fractional crystallization of hydrous, mantle-derived island arc basalt (IAB) magma or dehydra-tion melting of lower crustal amphibolite. As is often the case, when two different processes are suggested for the same phe-nomenon, both processes are probably occurring. In a former study, Brophy (2008) proposed that the REE–SiO 2 system-atics of mafic to felsic magmas in oceanic arc environments could be used to distinguish between these two processes in natural arc lavas and/or intrusives. Because the 2008 study was entirely model based, it requires some form of field veri-fication before REE–SiO 2 systematics can be accepted as a useful geochemical tool. The present study consists of a pet-rologic and geochemical study of a natural example of partial melting of island arc crust from the Asago Body within the Yakuno ophiolite located on Honshu Island, Japan (Fig. 1). The goal of the study is to evaluate the proposed REE–SiO 2 systematics of Brophy (2008) for dehydration melting of lower crustal amphibolite. The Yakuno migmatites were first studied by Suda (2004) who concluded that they were gener-ated by dehydration melting of island arc crustal amphibolite.Abstract The two most commonly invoked processes for generating silicic magmas in intra-oceanic arc environments are extended fractional crystallization of hydrous island arc basalt magma or dehydration melting of lower crustal amphibolite. Brophy (Contrib Mineral Petrol 156:337–357, 2008) has proposed on theoretical grounds that, for liquids >~65 wt% SiO 2, dehydration melting should yield, among other features, a negative correlation between rare earth ele-ment (REE) abundances and increasing SiO 2, while frac-tional crystallization should yield a positive correlation. If correct, the REE–SiO 2 systematics of natural systems might be used to distinguish between the two processes. The Per-mian-age Asago body within the Yakuno Ophiolite, Japan, has amphibolite migmatites that contain felsic veins that are believed to have formed from dehydration melting, thus forming an appropriate location for field verification of the proposed REE–SiO 2 systematics for such a process. In addi-tion to a negative correlation between liquid SiO 2 and REE abundance for liquids in excess of ~65 % SiO 2, another important model feature is that, at very high SiO 2 contents (75–76 %), all of the REE should have abundances less thanCommunicated by T. L. Grove.X. Pu · J. G. Brophy (*)Department of Geological Sciences, Indiana University, Bloomington, IN 47405, USA e-mail: brophy@ X. Pue-mail: pux@T. TsujimoriThe Pheasant Memorial Laboratory for Geochemistryand Cosmochemistry (PML), Institute for Study of the Earth’s Interior, Okayama University, Misasa, Tottori-Ken 682-0193, Japane-mail: tatsukix@misasa.okayama-u.ac.jpContrib Mineral Petrol (2014) 168:10601060 Page 2 of 12REE–SiO 2 systematics for amphibolite melting and basalt fractionation in oceanic island arcsIt is commonly assumed that amphibolite melting is simply the reverse process of basalt fractionation, and therefore, the two processes cannot be distinguished from one another on chemical grounds. This is not true. During the dehydra-tion melting of amphibolite, silicic melts are generated by one or more reactions of the type shown below (Rushmer 1991; Beard and Lofgren 1991; Rapp and Watson 1995)This reaction will continue to produce silicic melt until all of the original hornblende is consumed. Thus, the REE–SiO 2 systematics of the silicic melt will alwaysHbd +Na-rich plag +Fe-ox =cpx +opx +Ca-rich plag +Fe-ox +silicic melt.be controlled by the combined presence of hornblende, plagioclase, orthopyroxene and clinopyroxene. During fractional crystallization of hydrous, IAB magma, horn-blende is most likely present as a crystallizing phase in the lower crust (Davidson et al. 2007), but the extent to which it is a significant crystallizing phase is still uncer-tain (e.g., Davidson et al. 2013). Thus, in many arc sys-tems, extended basalt fractionation may be dominated by olivine, clinopyroxene, orthopyroxene and Fe-oxide, but not hornblende. From the standpoint of REE–SiO 2 system-atics, the potentially different role played by hornblende in dehydration melting of amphibolite and extended IAB fractionation may be very significant. The reason for this is emphasized in Fig. 2, which shows the variation in horn-blende-liquid D values [plotted as log(D )] versus liquid SiO 2 for La and Yb. For both elements, there is a steadyFig. 1 Generalized map show-ing the location of the Asago Body in the Yakuno Ophiolite (dark colored mafic units) and the amphibolite migmatites that are the focus of this study (after Suda 2004)Contrib Mineral Petrol (2014) 168:1060 Page 3 of 12 1060increase in log(D ) and therefore D with increasing liquid SiO 2. Furthermore, the partitioning behavior eventually changes from incompatible (D < 1) to compatible (D > 1). For La, this switch occurs at around 75 wt% SiO 2, but reaches as low as ~60 % SiO 2 for Yb. Of the four minerals mentioned above (olivine, plagioclase, clinopyroxene and hornblende), hornblende is the only one that displays this behavior to such a large extent. What this means is that, for SiO 2-rich liquids, the presence or absence of horn-blende can translate into dramatically different partitioning behavior for the REE.Brophy (2008) modeled the variation in La and Yb with increasing liquid SiO 2 for both fractional crystalliza-tion of IAB basalt and dehydration melting of lower arc crust amphibolite. The modeling combined major element mass-balanced fractional crystallization models and exper-imentally based amphibolite melting models with quanti-tative expressions describing the log (D )–SiO 2 variations for La and Yb shown in Fig. 2. The results are summarized in Fig. 3, which shows the predicted variation in La and Yb abundances for batch melting of amphibolite and frac-tional crystallization of IAB basalt. Fractional melting and accumulated fractional melting show similar overall results and are not shown here. In both cases, the initial gabbro or basalt was assumed to contain 50 wt% SiO 2. The results are expressed in terms of an element enrichment factor in the liquid, C l /C o , where C l is the concentration of the element in the liquid and C o is the original concen-tration of the element in the source rock (for melting) or the original basalt magma (for crystallization). The most important feature of Fig. 3 is that, for liquids in excess of ~65 % SiO 2, amphibolite melting reveals a negative cor-relation between La and Yb abundances and SiO 2 content, while IAB basalt fractionation shows a positive correla-tion up to SiO 2 contents of around 70 wt% after which a negative correlation is observed. These differences reflect (1) the increasing compatibility of La and Yb in horn-blende with increasing liquid SiO 2 and (2) the dominant role played by hornblende during melting and the minor role during crystallization. If these model predictions are correct, then they could provide an important geochemical tool for distinguishing between a melting and fractional crystallization origin for natural silicic lavas in intra-oce-anic arc environments.Fig. 2 Hornblende–liquid La and Yb D values versus SiO 2 content of co-existing liquid (glass). Data sources include Sisson (1994), Klein et al. (1997), Dalpe and Baker (2000) and Brophy et al. (2011)Fig. 3 Predicted REE–SiO 2 variations (from Brophy 2008) for lower crustal amphibolite melting, hornblende-free mid-crustal fractionation of basalt and hornblende-bearing mid-crustal fractionation of basaltContrib Mineral Petrol (2014) 168:10601060 Page 4 of 12Predicted REE–SiO 2 systematics for amphibolite meltingThe most controversial part of the Brophy (2008) modeling is the predicted REE–SiO 2 systematics for amphibolite melting, the field verification of which constitutes the essence of the current study. The gist of the predicted systematics is sum-marized in Fig. 4, which shows predicted liquid enrichment factors (C l /C o ) for representative light (La), middle (Gd) and heavy (La) rare earth elements (REEs) as a function of liquid SiO 2 content. Two major predictions can be made. First, for liquids greater than around 65 % SiO 2, all of the REE should show a negative correlation with increasing liquid SiO 2. Sec-ond, at very high liquid SiO 2 contents (around 75–76 %), the LREE should all show enrichment values <1. It is these two theoretical predictions that are to be evaluated in this study.Analytical methodsBulk rock major and trace element analyses were conducted by XRF and LA-ICPMS at Michigan State University fol-lowing analytical procedures described in Deering et al. (2008). Major element compositions of minerals were determined by electron microprobe analysis (EMPA) on a Cameca SX50 located at Indiana University. Operating con-ditions included a 15 kV acceleration voltage, 20 nA sample current and a beam diameter of 3 microns. Na 2O was always analyzed first to reduce any effects of volatilization/diffu-sion. Accessory mineral percentages in the mafic amphibo-lite were determined by initial EMPA of individual miner-als followed by image analysis of multiple (15) back scatter electron images for four different amphibolite samples.The Yakuno OphioliteThe Permian-aged Y akuno Ophiolite is located on Honshu Island, Southwest Japan (Fig. 1). Three different segments havebeen identified within the ophiolite including unusually thick oceanic crust, island arc crust and oceanic back-arc basin crust (Ishiwatiri 1985; Hayasaka 1990; Ichiyama and Ishiwatari 2003). The Asago body is a fault-bounded tectonic slice within the ophiolite suite. It is comprised of three structural units: a Lower Unit (L-Unit), Middle-Unit (M-Unit) and Upper-Unit (U-Unit) (not shown in Fig. 1). The M-Unit is thought to repre-sent a lower to middle crustal section of an intra-oceanic island arc (Hayasaka 1990). The amphibolite migmatites sampled for this study were located in the lower part of the M-Unit, near the boundary of the M- and L-Unit (Suda 2004). They were col-lected along a short southwesterly transect following the bot-tom of a small stream valley (Fig. 1). A total of ten samples were collected. Two samples represent mafic amphibolites without felsic veins, while the rest of the samples consist of intermixed mafic amphibolite and felsic veins. According to Suda (2004), the P –T conditions during the formation of these migmatites are estimated to be around 850 °C and 3.5–5.5 kbar with a peak metamorphic grade of granulite facies.Sample descriptionThe amphibolites show a clear migmatite signature with felsic veins and pockets dispersed throughout the amphibo-lite host (Fig. 5). The contacts between the mafic amphibo-lite host and the felsic material are always sharp, suggest-ing that the felsic melts were actually generated elsewhere and intruded into their current position through joints and fractures in the host rock. The scale and shape of the fel-sic intrusions vary from sample to sample. The amphibolite host consists of primary amphibole, plagioclase and minor amounts of augite. Detailed analysis of multiple samplesindicates very small volumes of sphene (0.5 wt%), apatiteFig. 4 Predicted variations in liquid enrichment factors (C l /C o ) for La (HREE), Gd (MREE) and Yb (HREE) from the model of Brophy (2008)Fig. 5 Field photograph showing one of the amphibolite migmatite outcrops that are the focus of this studyContrib Mineral Petrol (2014) 168:1060 Page 5 of 12 1060(0.15 wt%) and zircon (0.05 wt%). The amphibole is calcic and ranges from magnesio-hornblende to ferro-hornblende (Leake et al. 1997). The plagioclase has been extensively albitized with some crystals reaching Ab100 in composition. Most crystals show some degree of saussuritization. A few plagioclase grains have compositions around Ab35, suggest-ing that the original (pre-albitized) plagioclase was of this general composition. Augite is largely unaltered and com-positionally uniform at around Wo46En36Fs18. Secondary minerals include actinolite, prehnite, epidote, chlorite and saussurite minerals. Actinolite, though present in only small amounts, can partially or completely replace hornblende. Hornblende is occasionally replaced by chlorite. Small amounts of epidote and prehnite occur as discrete crystals.The felsic veins consist of primary plagioclase and quartz. Quartz shows up as aggregates of fine-grained crys-tals and or intergrowths with plagioclase. Individual pla-gioclase crystals are still recognizable under cross-polar in microscope, but they have been mostly saussuritized. Most plagioclase crystals have been completely albitized (Ab99–Ab100). Subhedral hornblende xenocrysts can be found floating in the felsic material.The hydrous secondary minerals in both the amphibo-lite and felsic intrusions point toward a significant prehnite to greenschist facies retrograde metamorphism that post-dated the peak metamorphic event (when partial melting occurred) by some undetermined amount of time.Whole rock geochemistryWhole rock major and trace element data are listed in Table 1. Total iron is reported as FeO*. SiO2 contents (on an anhydrous basis) range from 47 to 55 % in the mafic amphibolites and from 76 to 81 % in the felsic intrusion samples. Figure 6 shows Harker variation diagrams for selected oxides. Within both the mafic and felsic groups, Al2O3, TiO2, FeO*, MgO and CaO steadily decrease with increasing SiO2, while Na2O and K2O show a rough increase with increasing SiO2.Figure 7 shows a chondrite-normalized trace element spider diagram for both mafic and felsic samples using the normalization factors of McDonough and Sun (1995). The mafic and felsic samples have similar overall patterns, but the felsic samples are enriched in the incompatible ele-ments and depleted in the compatible elements compared with the mafic samples. The overall patterns are flat with several important anomalies including positive Ba, slightly negative Nb and Ti, and strong P depletion. Also seen are positive Ba anomalies more negative Ti (mostly in felsic samples) and Nb anomalies. Felsic samples have higher incompatible element abundances and lower compatible element abundances compared with the mafic samples. The overall flat patterns in the chondrite-normalized pro-files and the presence of positive Ba and negative Nb and Ti anomalies are consistent with an island arc setting as origi-nally suggested by Hayasaka (1990) and Suda (2004).Figure 8 shows chondrite-normalized REE patterns for both the mafic and felsic samples. The patterns for the mafic samples are flat with general abundances ranging from about 6 to 20 times those of chondrite. The patterns for the felsic samples are somewhat fractionated and con-cave upwards. Relative to the mafic samples, the inclined patterns for the felsic samples have resulted primarily from HREE depletion with only slight LREE enrichment. Relationship between amphibolite host and felsic veinsTwo important questions for this study are (1) do the felsic veins represent partial melts of amphibolite and; (2) do the felsic veins represent in situ partial melting of the amphi-bolites in which they are hosted? Several lines of evidence support an amphibolite melting origin for the felsic veins. First, the field relations are those of a classic migmatite, which are almost universally viewed as representing partial melting (e.g., Sawyer 2008). Second, relative to the host amphibolites, the felsic veins show slight LREE enrichment and significant HREE depletion. Furthermore, the HREE display a concave upwards pattern. This pattern is entirely consistent with melting of a source rock that contained sig-nificant residual hornblende at the time of melt extraction (i.e., an amphibolite). Finally, Fig. 9 compares the major element chemistry of the host amphibolites and felsic veins with the experimental melts of Beard and Lofgren (1991) for the dehydration melting of amphibolite over a pressure range of 3–6.9 kbar. All of the felsic veins have SiO2 con-tents that are greater than the most SiO2-rich experimental liquid. However, for all of the oxides, the felsic veins lie on extensions of the experimental liquid trends. When taken together, these three lines of reasoning strongly support an amphibolite melting origin for the felsic veins.It is noteworthy that all of the felsic samples display a significant positive Eu anomaly (Fig. 8), the origin of which is unclear. Plagioclase preferentially retains Eu2+, while hornblende and augite preferentially exclude Eu2+ (e.g., Brophy et al. 2011). Thus, the positive anomaly could be a result of plagioclase accumulation, suggesting a fractional crystallization origin for the silicic veins, or partial melt-ing of amphibolite wherein the silicic melt is in equilibrium with hornblende and/or augite during the melting process. Because there is so much field and textural evidence sug-gesting a partial melting origin, the positive Eu anomalies are most likely a reflection of the latter.Several lines of evidence also suggest that the host amphibolites do not represent the true source rock for theContrib Mineral Petrol (2014) 168:1060 1060Page 6 of 12felsic veins and that the veins were generated elsewhere (presumably deeper) and then intruded into the current host rocks. First, the contacts between the felsic veins and host amphibolite are universally sharp, which is inconsist-ent with in situ partial melting (e.g., Sawyer 2008). Sec-ondly, the host amphibolites are dominated by hornblende with only very small amounts of augite. Given that augite is a major reaction product during amphibolite melting, the abundance of hornblende and lack of augite argue against partial melting in the host amphibolites.Modeling REE–SiO2 systematicsThe REE–SiO2 systematics for partial melting of the Asago body amphibolites was modeled using the same procedureTable 1 Whole rock major and trace element databd Below detection limit Sample14-M16-M15-M17-M13-M20-M12-M19-M18-F17-F11-F20-FSiO243.1845.747.2148.3348.354951.252.774.9376.8577.278.76 TiO2 1.15 1.44 1.32 1.230.94 1.150.59 1.250.180.260.020.04 Al2O315.3415.9315.9216.4716.7815.414.1713.813.1611.6213.2911.13 FeO T14.5510.839.689.4610.1310.528.548.38 1.03 1.370.080.22 MnO0.180.180.180.160.160.170.170.170.020.0200.01 MgO7.39 6.64 6.18 6.15 5.74 6.78.36 5.610.310.670.010.02 CaO9.069.411.710.178.0589.529.04 2.9 2.53 2.21 1.96 Na2O 1.93 3.1 2.86 3.25 3.49 3.5 2.68 4.35 4.81 4.02 4.88 5.06 K2O0.480.610.460.520.830.970.770.450.380.310.640.18 P2O50.020.190.180.180.10.130.080.160.030.020.010.01 LOI 5.04 4.67 3.14 2.91 4.22 3.17 2.86 3.06 2.07 2.12 1.59 2.55 Total98.3298.6998.8398.8398.7998.7198.9498.9799.8299.7999.9399.94 Ni1564566827678651bd bd bd bd Cu926428254019296742661Zn5687727178836157bd bd bd bd Rb107661114119647bd Sr158413458568315407252252309326299219 Zr15817656938636611501372359 Ba125.4131.6110.5108.5208.8253.9151.611.7115.391.5197.779.5 La 1.06 5.3 4.45 4.578.07 4.92 4.25 5.0110.467.18.7611.57 Ce 2.8314.6312.5813.121.4814.049.5212.8221.9213.9218.7624.53 Pr0.43 2.43 2.06 2.21 3.24 2.28 1.24 1.36 1.92 1.18 1.74 2.42 Nd 2.3912.4810.6211.8715.4111.66 5.66 5.17 6.07 3.56 5.788.43 Sm0.77 3.68 3.23 3.65 4.24 3.57 1.59 1.060.980.410.79 1.48 Eu0.39 1.25 1.12 1.24 1.1 1.130.620.960.730.660.470.34 Gd 1.14 4.48 3.97 4.36 4.82 4.2 2.01 1.10.960.360.8 1.13 Y9.2134.0229.2832.7438.8433.2716.737.78.7 1.5 3.94 4.18 Dy 1.38 5.16 4.49 4.94 5.68 4.89 2.46 1.07 1.030.220.420.72 Ho0.32 1.130.99 1.08 1.25 1.060.570.230.260.060.060.13 Lu0.140.450.390.430.560.450.270.120.20.070.040.09 Yb0.88 3.02 2.69 2.95 3.77 3.09 1.780.74 1.20.310.210.55 Tb0.210.80.710.780.870.760.380.170.180.050.050.15 V82732730631932130625632.99.8835.89 4.49 6.02 Cr24.65184.2161.4174.340.6169389.2 6.8 4.9817.38 3.04 3.23 Nb0.5 2.21 1.94 1.87 2.35 2.37 1.1 2.46 3.89 2.8 1.250.77 Hf0.53 2.31 2.03 1.82 2.55 2.28 1.14 2.82 3.19 3.010.59 2.65 Ta0.280.140.130.150.18 1.180.130.270.620.54 5.470.67 Pb0.62 1.26 1.15 1.38 1.82 1.04 1.09 4.819.49 4.97.11 1.2 Th0.150.120.160.140.230.120.750.17 2.340.5 2.67 6.15 U0.050.070.070.080.10.080.250.130.740.120.740.86Contrib Mineral Petrol (2014) 168:1060 Page 7 of 12 1060Fig. 6 Harker variation diagrams showing the mafic amphibolite hosts (filled circles ) and felsic veins (open circles )Fig. 7 Chondrite-normalized spider diagram for both the mafic amphibolite hosts (filled circles ) and felsic veins (open circles )Fig. 8 Chondrite-normalized REE diagram for both the mafic amphi-bolite hosts (filled circles ) and felsic veins (open circles )Contrib Mineral Petrol (2014) 168:10601060 Page 8 of 12employed by Brophy (2008). As described previously, a numerical amphibolite melting model based on existing experimental data was combined with liquid SiO 2-depend-ant REE partition coefficients to calculate model liquid REE abundances as a function of liquid SiO 2 content. In this study, the numerical melting model of Brophy (2008) was modified in two important ways. First, because the Asago amphibolites do not contain quartz, it was removed as a melting phase. Second, the observed accessory minerals (sphene, apatite and zircon) have been added to the melt-ing history. Their initial abundances have been set at sphene (0.5 %), apatite (0.15 %) and zircon (0.05 %), which repre-sent their average observed modal abundances in the amphi-bolites. It is further assumed that all accessory minerals are completely refractory throughout the amphibolite melting. Table 2 summarizes the overall numerical melting model employed. The SiO 2-dependant REE D values for all major minerals are the same as those used by Brophy (2008). D values for the accessory minerals are based on the pub-lished sets of Fujimaki (1986) (apatite), Luhr et al. (1984) (sphene) and Sano et al. (2002) (zircon). These particular sets were chosen because, for each mineral, they represent (1) an overall D value pattern representative of that estab-lished from multiple data sets (i.e., concave upwards, con-cave downwards) and (2) the highest overall D values. In all cases, D values for any missing elements were estimated by interpolation and the overall D value profiles were then“smoothed” to remove any irregularities.Fig. 9 Comparison of the mafic amphibolite hosts (filled circles ) and felsic veins (open circles ) with experimental glasses (gray fields ) gener-ated by the dehydration melting of natural amphibolites at pressures of 3–6.9 kb (Beard and Lofgren 1991)Contrib Mineral Petrol (2014) 168:1060 Page 9 of 12 1060Figure 10 shows the modeled variations in liquid REE abundance (chondrite-normalized) as a function of liquid SiO2 content for all of the REE for which natural abun-dance data are available. Results are shown for both batch and fractional melting and cover liquid compositions rang-ing from 60 to 76 % SiO2. Also shown are observed abun-dances for the mafic amphibolites and felsic veins. Eu was not modeled due to the uncertainty in Eu D values (Brophy 2008). The modeled variations assume initial abundances (C o) equal to the average of the mafic amphibolite samples. Because the felsic veins are plotted on an anhydrous SiO2 basis, they all plot at SiO2 contents >76 % SiO2. A com-parison of the model and observed REE abundances in the felsic veins shows excellent agreement for the MREE and HREE (Sm–Yb), but rather poor agreement for the LREE (La–Nd) where observed abundances are higher than the predicted values.DiscussionThe Brophy (2008) model had two specific predictions. First, all of the REE should display negative REE–SiO2 correlations for liquid SiO2 greater than around 65 wt%, and second, the REE abundances in very SiO2-rich liquids (around 75–76 % SiO2) should be the same or less than those in the source rock (i.e., C l/C o≤ 1). Figure 10 shows that the natural felsic samples cover a very narrow range of SiO2 content (76–81 % on an anhydrous basis) and there-fore cannot be used to assess a negative (or positive) REE–SiO2 variation. Thus, the first of Brophy’s (2008) model predictions cannot be evaluated. However, Fig. 10 does show that, with the exception of the LREE, all of the natu-ral felsic rocks display REE abundances that are the same or less than those in the mafic amphibolites. Furthermore, with the exception of the LREE, the predicted model values agree very well with the observed abundances in the felsic veins, thus confirming, in general, the second of Brophy’s (2008) model predictions. Nevertheless, the discrepancy between the predicted and observed values for the LREE cannot be ignored, and this is turned to now.Figure 11a shows a range of predicted REE profiles for a model 76 % SiO2 melt. The individual REE profiles were constructed by combining the model enrichment factors for (C l/C o) for a 76 % SiO2 model melt with the corresponding initial element values in each of the natural amphibolites (C o). Figure 11b compares this range with the observed profiles in the felsic veins. The results further highlight the discrepancy for the LREE and the good agreement for the MREE to HREE. What would be required to explain the discrepancy would be an amphibolite source rock that is LREE-enriched relative to ones in which the felsic veins currently reside. It is important to recall that the felsic veins most likely are the result of partial melting of some other amphibolite source rock presumably nearby and perhaps at a greater depth. Thus, it is possible that some other amphi-bolite that contains the required LREE-enriched signature could have been the actual source rock.Figure 12 shows the REE profiles reported by Suda (2004) for a moderate number of amphibolites from the Asago body of the Yakuno amphibolites. The amphibolites turn out to be of two types. The first type, referred to here as Group 1 amphibolites, has flat to slightly convex profiles with chondrite-normalized values ranging from around 10 to 50. These features are similar to those of the amphibo-lites sampled in this study. Significantly, the second type (Group 2 amphibolites) displays a fractionated profile with moderate LREE enrichment relative to the Group 1 amphi-bolites. In Fig. 13, the five group 2 amphibolites of Suda (2004) have been used as the amphibolite source rock to, once again, calculate a range of REE profiles for a model 76 % SiO2. When these results are compared with the observed felsic veins, one sees perfect agreement for all elements including the LREE. Thus, if one were to assume that the true source rock for the felsic veins was an amphi-bolite with REE abundances similar to the group 2 amphib-olites, then both of Brophy’s (2008) theoretical predictions are completely confirmed.ConclusionsThe main goal of this study was to evaluate the REE–SiO2 systematics predicted by Brophy (2008) for the formationTable 2 Amphibolite melting modelStage I Stage II Stage III Stage IVModal abundance—% melting variationhbd43.715.9000plag49.747.644.629.70cpx013.922.819.80opx059.9 4.90mag45430ilm22220Sphene0.50.50.50.50Apatite0.150.150.150.150Zircon0.050.050.050.050Melt010******* Liquid SiO2—% melting variationBatch melting − wt% SiO2= 76.035 − 0.35055(x) + 0.005361(x)2−0.00021826(x)3Fractional melting—wt% SiO2= 76.504 − 0.73607(x) + 0.01818(x)2−0.00088319(x)3x=W t% melting。

Simulations of Rayleigh’s Wave on Curved Surface

Simulations of Rayleigh’s Wave on Curved Surface Shih-yu Shen;Chin-Yu Wang【期刊名称】《应用数学（英文）》【年(卷),期】2013(4)6【摘要】Impulsive line load in a half-space (Lamb’s problem) can be solved with a closed form solution. This solution is helpful for understanding the phenomenon of Rayleigh’s waves. In this article, we use a boundary element method to simulate the solution of an elastic solid with a curved free surface under impact loading. This problem is considered difficult for numerical methods. Lamb’s problem i s calculated first to verify the method. Then the method is applied on the problems with different surface curvatures. The method simulates the phenomenon of Rayleigh’s wave propagating on a curved surface very well. The results are shown in figures.【总页数】5页(P963-967)【关键词】Elastodynamics;Lamb’s;Problem;Boundary;Element;Method;Rayleigh’s; Wave【作者】Shih-yu Shen;Chin-Yu Wang【作者单位】Department of Mechanical Engineering, Cheng Shiu University, Taiwan;Institute of Applied Mathematics, National Cheng-Kung University, Taiwan【正文语种】中文【中图分类】O1【相关文献】1.Stepwise joint inversion of surface wave dispersion, Rayleigh wave ZH ratio, and receiver function data for 1D crustal shear wave velocity structure [J], Ping Zhang;Huajian Yao2.Numerical Simulation of Surface Acoustic Wave and Detection of Surface Crack in Steel* [J], LIN Bin;ZHANG Lei;DORANTES Dante;LI Yanning;FU Xing;HU Xiaotang3.Numerical Simulation of Surface Acoustic Wave and Detection of Surface Crack in Steel [J], 林滨;张磊;多伦雷·丹特;李艳宁;傅兴;胡小唐4.Simulation of Surface Wave with Large Eddy Simulation in σ-Coordinate System [J], 王玲玲5.A hybrid inversion method of damped least squares with simulated annealing used for Rayleigh wave dispersion curve inversion [J], Lu Jianqi;Li Shanyou;Li Wei;Tang Lihua因版权原因，仅展示原文概要，查看原文内容请购买。

有关波浪岩的英语作文

有关波浪岩的英语作文英文回答：Wave Rock, an awe-inspiring natural rock formation, is located in the Wheatbelt region of Western Australia, approximately 350 kilometers east of Perth. This massive wave-like structure is one of the most iconic landmarks in the state and a popular tourist destination.Formed over millions of years by the erosion of soft sandstone and the deposition of harder rock, Wave Rock stands an impressive 15 meters high and stretches for over 100 meters. Its distinctive shape resembles a giant wave frozen in time and has earned it the name "The Rock that Time Forgot."The unique beauty of Wave Rock is enhanced by its vibrant colors, which range from deep reds and oranges to soft pinks and whites. These colors are created by the presence of minerals such as iron oxide, which oxidizesover time to produce the stunning hues.Wave Rock is a popular spot for hiking, photography, and picnicking. Visitors can walk along the base of the rock, admiring its intricate textures and colors, or climb to the top for panoramic views of the surrounding countryside. There are also various picnic areas nearby where visitors can relax and enjoy the scenery.In addition to its natural beauty, Wave Rock holds cultural significance for the Aboriginal people of the region. The Noongar people believe that the rock is a sacred site and was created by the Rainbow Serpent, a mythological creature that is said to have shaped the land.Wave Rock is an extraordinary natural wonder that attracts visitors from around the world. Its unique shape, vibrant colors, and cultural significance make it a must-see destination for anyone exploring Western Australia.中文回答：波浪岩。

Rayleigh波在浅圆凹陷地形附近的散射:高频解答

Rayleigh波在浅圆凹陷地形附近的散射：高频解答
梁建文;李方杰;顾晓鲁
【期刊名称】《地震工程与工程振动》
【年(卷),期】2005(25)5
【摘要】利用波函数展开法给出了Rayle igh波在浅圆凹陷地形附近散射的一个高频解析解,并分析了入射频率、凹陷地形宽度和深度等因素对波散射的影响。

数值结果表明,由于Rayle igh波幅值随深度而衰减,凹陷地形表面位移幅值整体上较小,且随着凹陷地形深度的增加而减小;由于Rayle igh波幅值还随频率而衰减,随着入射频率的升高,凹陷地形表面位移幅值逐渐减小;由于凹陷地形的屏障作用,在入射波的近端,地表位移分布变得相对复杂,地表位移峰值出现在左角点附近,而在入射波远端,地表位移分布相对简单,地表位移峰值出现在距凹陷地形较远的地方。

【总页数】6页(P24-29)
【关键词】凹陷地形;Rayleigh波;散射;高频;解析解
【作者】梁建文;李方杰;顾晓鲁
【作者单位】天津大学土木工程系
【正文语种】中文
【中图分类】P315.3
【相关文献】
1.圆弧状凹陷地形对平面P波的散射:高频解答 [J], 杨彩红
2.SH波在多个浅埋圆形孔洞附近的多个含孔半圆形凸起地形处的散射 [J], 李敏;
冯云亭;贲伟
3.浅埋圆柱形弹性夹杂附近等腰三角形凸起地形引起的SH波的散射 [J], 刘刚;刘殿魁;杜永军;陈海涛
4.圆弧形凹陷地形对平面SH波散射问题的级数解答 [J], 袁晓铭;廖振鹏
5.SH波对浅埋圆形弹性夹杂附近任意三角形凸起地形的散射 [J], 刘刚;刘殿魁因版权原因，仅展示原文概要，查看原文内容请购买。

4.2 超声波分类

3）别名：1887年，瑞利（Rayleigh wave）首先指出其存在，所以表面波也叫瑞利波。4）传播介质：椭圆运动可视为纵向振动与横向振动的合成，即纵波与横波的合成，所以表面波固体表面传播。5）应用：钢轨探伤中70°探头因声速的扩散性有时会分离出表面波在钢轨表面传播。
板波又称兰姆波，当固体介质的尺寸进一步收到限制而形成板状，且板厚小到一定程度时，瑞利波就不会存在而只能产生各种类型的板波。
球面波
1．声源为点状球体，波阵面是以声源为中心的球面2．声强与距声源距离的平方成反比
柱面波
1．声源为一无限长的线状直柱，波阵面是同轴圆柱面2．声强与距声源的距离成反比
不同波形分类及特性表
而探伤用的超声波是一种活塞波，是平面波和球面波的合成。
（2）横波S(T)
1）定义：介质中质点的振动方向与波的传播方向互相垂直的波。2）特点：当介质质点受到交变的剪切应力（剪切力）作用时，产生切变形变，从而形成横波。3）别名：传递横波时介质承受剪切力并产生切变变形，故横波又称为剪切波或切变波。
4）传播介质：因液体和气体无法承受剪切力，所以横波只能在固体介质中传播。5）应用：钢轨探伤中斜探头或者37°、70°探头就是利用横波在检测钢轨。
Байду номын сангаас
在板厚与波长相当的薄板中传播的波，一般用于检测薄板材，在钢轨探伤中应用较少。
（4）板波P
按振动持续时间分类
按波的形状分类
不同波形分类及特性
波形
特性
平面波
1．无限大平面（即波长与声源尺寸相比可忽略不计）作谐振动时，在各向同性的弹性介质中传播的波2．如不考虑介质吸收波的能量，声压不随与声源的距离而变化
超声波分类
（1）纵波L

黏弹性与弹性介质中Rayleigh面波特性对比研究

黏弹性与弹性介质中Rayleigh面波特性对比研究高静怀;何洋洋;马逸尘【期刊名称】《地球物理学报》【年(卷),期】2012(55)1【摘要】Rayleigh面波的频散特性可以用来研究地表浅层结构.本文使用时域有限差分法来模拟复杂黏弹性介质中的Rayleigh面波,研究了Q值对面波频散特性的影响.文中采用旋转交错网格有限差分,以非分裂卷积形式的完全匹配层为吸收边界,推出了求解二阶位移-应力各向同性黏弹性波动方程的数值方法.为了检验数值解的精度,首先将简单模型的正演结果与解析解对比,验证了方法的正确性；然后模拟了横向缓变层状介质和含有洞穴的介质中的面波,对弹性和黏弹性介质中的面波的频散特性进行对比分析.模拟结果表明浅层Q值对面波的频散特性有显著的影响；强吸收情况下,高阶面波的能量相对低阶面波能量显著增强.%Dispersion properties of Rayleigh-type surface waves can be used for imaging and characterizing the shallow subsurface. This paper models Rayleigh waves in complex viscoelastic media by using the time-domain finite difference method on the rotated staggered grid. We compared the dispersion properties of the viscoelastic Rayleigh wave with the elastic one. We proposed a method to model the Rayleigh wave based on the second-order displacement-stress viscoelastic wave equations and the unsplit convolutional perfectly matched layer absorbing boundary condition. The validity of our method is tested by two examples. Then, the wave fields are calculated in a laterally heterogeneous media and a media with cavity. We analyzed the dispersionproperties of the Rayleigh waves. The dispersion curve varies considerably with quality factor Q in shallow subsurface; the higher modes of Rayleigh waves are generated and possess significant amounts of energy for strong attenuation.【总页数】12页(P207-218)【作者】高静怀;何洋洋;马逸尘【作者单位】西安交通大学电信学院波动与信息研究所,西安710049;海洋石油勘探国家工程实验室,西安710049;西安交通大学电信学院波动与信息研究所,西安710049;海洋石油勘探国家工程实验室,西安710049;西安交通大学理学院,西安710049【正文语种】中文【中图分类】P631【相关文献】1.超声表面波在均匀弹性介质中传播的数值仿真 [J], 阚文彬;李勇峰;朱合范;潘红良2.黏弹性介质瑞雷波有限差分模拟与特性分析 [J], 袁士川;宋先海;张学强;赵素涛;蔡伟;胡莹3.层状黏弹性介质中Rayleigh波频散曲线“交叉”现象分析 [J], 张凯;张保卫;刘建勋;徐明才4.饱和孔隙弹性介质中的Rayleigh波及一维动力学问题 [J], 黄江;曾心传5.新书介绍——《弹性介质中的表面波理论及其在岩土工程中应用》 [J],因版权原因，仅展示原文概要，查看原文内容请购买。

格兰·泰勒棱镜两类视场角的比较研究

格兰泰勒棱镜两类视场角的比较研究
马丽丽;李国华;彭捍东
【期刊名称】《曲阜师范大学学报（自然科学版）》
【年(卷),期】2004(030)004
【摘要】以格兰·泰勒棱镜为例,推导了沿主截面和垂直主截面两正交方向的最大视场角,并在常用结构角下比较了两类视场角的大小及它们随波长的变化关系,得知沿主截面的视场角对光路调整影响较大.
【总页数】3页(P68-70)
【作者】马丽丽;李国华;彭捍东
【作者单位】曲阜师范大学激光所,273165,山东省曲阜市;曲阜师范大学激光所,273165,山东省曲阜市;曲阜师范大学激光所,273165,山东省曲阜市
【正文语种】中文
【中图分类】O436
【相关文献】
1.格兰-泰勒棱镜和格兰-付科棱镜透射比的比较研究 [J], 唐恒敬;吴福全;邓红艳
2.过渡层在格兰-泰勒棱镜减反射膜中的应用 [J], 郝殿中;韩培高
3.400-1100 nm波段用于格兰泰勒棱镜减反射膜的研制 [J], 郝殿中;苏富芳;王召兵
4.空气隙型格兰泰勒棱镜斜面减反射膜的设计 [J], 郝殿中;王庆;夏云杰;吴福全;宋连科
5.格兰型棱镜视场角的光谱特性研究 [J], 张冬青;吴福全;范树海;王宁
因版权原因，仅展示原文概要，查看原文内容请购买。

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