辽宁本溪晶花洞洞穴特征及形成时代

辽宁本溪晶花洞发育于中奥陶世马家沟组(O₂m)厚层灰岩中,主要受近SN、NE断裂控制,沿近SN断裂发育高度不同的4层洞穴。洞内沉积物以化学沉积为主,机械沉积较少。通过测定洞内外的温度、湿度及CO₂含量,对比研究发现洞穴封闭性较好,与外界大气循环较差。在与洞外干河河流阶地的高程及形成时代上的对比研究基础上,结合主洞所采年龄样的铀系法测年(111.5±5.3 ka),初步推断晶花洞主洞发育于晚更新世。     

CHARACTERISTICS OF LARGE PULSES OF RADIATED FIELDS FROM CLOUD FLASH DISCHARGES

Observations show that the sequences of microsecond-scale pulses are produced in cloud flashdischarge processes.In the present work we report on measurements of larger bipolar pulses(LBP)of the radiation fields which are classified into four types according to their waveshapes andpolarities of initial peak.Either positive or negative pulse contains two kinds of waveshapes:onewith a smooth rise and the other with 2 or 3 fast-rising pulse superimposed on the initial half cycle.The pulse waveshape characteristics in both time and frequency domains are as follows.Among2908 samples there are 45% of the positive polarity and 55% of the negative polarity.The positivepulses tend to have distinctly smaller values than negative pulses in rise time,half width and zero-crossing time of the initial peak.The peaks of positive pulse spectra tend to occur at a higherfrequency than those of negative pulses.Despite differences above,positive and negative pulseshave a similar total duration.     

翡翠文化与翡翠市场探释

中国人几千年来对翡翠有着特殊爱好,其融人了自古以来的玉石文化,它对中华民族的精神、意志、道德、哲理产生着巨大的影响。翡翠的探释是一门高雅的艺术,不但要从文化的层面来认识翡翠,而且还要多了解一些翡翠的专业知识和翡翠市场的发展现状。本文详细地介绍了目前国内几大翡翠市场和各市场的特点以及中国翡翠市场的发展史。     

Multi-scale Characteristics and Comprehensive Evaluation of Precipitation Heterogeneity in Guangxi

Aiming at the uneven spatial and temporal distribution of precipitation and frequent occurrence of drought and waterlogging disasters in Guangxi, the multi-scale characteristics and comprehensive evaluation of precipitation heterogeneity can provide scientific support for regional response to drought and waterlogging disasters and intelligent management of water resources. Based on the daily precipitation data of 87 grid points from 1961 to 2017 in Guangxi, the Precipitation Concentration Degree (PCD) and Precipitation Concentration Period (PCP) index were used to build day, pentad, ten days, month, season precipitation heterogeneity of multiple time scale level evaluation system. By using R/S analysis and geographical spatial analysis methods, the space-time evolution characteristics and climate division in Guangxi were discussed. The study showed that the spatial and temporal variation characteristics of PCD and PCP at the diurnal, synoptic and monthly scales were relatively consistent, and the heterogeneity of precipitation in Guangxi could be better expressed than that at the monthly and seasonal scales. The diachronic change of PCD in precipitation in Guangxi shows an increasing trend in northeast China and a decreasing trend in southwest China, and the trend of its future period is the same as the diachronic evolution. The spatial distribution of PCD in Guangxi has significant spatial autocorrelation and stratification heterogeneity, which are mainly reflected in the mean value, coefficient of variation and frequency of PCD. The comprehensive heterogeneity of precipitation in Guangxi is highly dispersed in the northeast, highly concentrated in the south, and slightly concentrated or dispersed in the northwest and central regions. The time-scale within a month is the best scale to express the non-uniformity of precipitation in Guangxi. If the advantages of more stable climatic and ten-day scales and more fine daily scales are taken into account, the use of climatic scale for daily sliding calculation and analysis will be the best way.     

滑坡-碎屑流冲击导引结构的离散元模拟

滑坡碎屑流对拦挡结构的直接冲击常产生较高的峰值冲击力和冲击能量,导致结构发生破坏而失效;而导引结构通过改变碎屑流的运动路径,可减缓其冲击效应,提高结构抗冲击能力。文章运用三维离散元模拟软件,结合室内休止角试验的结果,校准数值模拟参数,以三种不同导引结构(凹型圆弧、直线型、凸型圆弧)为变量进行数值模拟分析。研究结果表明:凹型圆弧结构B1可以有效地将碎屑流颗粒的冲击力进行转化,结构所受的法向力最小,切向力最大,对颗粒的导引作用最大。经过三种不同导引结构后,颗粒与滑槽之间的碰撞和摩擦是导致颗粒动能减小的主要原因;而三种不同导引结构对颗粒动能的耗散效果无显著差异。导引结构的作用对于颗粒堆积体积分布有显著的影响,主要影响区是靠近坡脚处,对导引结构之后的堆积区域的颗粒体积分布影响不显著。通过对冲击效应和堆积特性的研究,得到凹型圆弧结构形式最优,可以为碎屑流的防护工程抗冲击设计提供参考。     

中国传统聚落景观区划及景观基因识别要素研究

传统聚落景观区划是一项理论性和实践性都很强的工作,是文化景观区划研究的重要课题之一。基于中国传统聚落景观本身存在的地域性、系统性、稳定性、发展性、一致性、典型性和协调性等特点,本方案以传统聚落景观“意象”(Image) 的内部相似性为前提,以相对一致性原则作为景观区域划分的主导性原则,综合考虑其他原则,如环境制约性原则、文化主导性原则、地域完整性原则、相对一致性原则、面的覆盖性原则、层次性原则和综合性原则等,将全国聚落景观初步划分为3 个大尺度的景观大区、14 个景观区和76 个景观亚区。以往关于文化区的识别,主要从文化特征的角度进行的;关于传统聚落景观区的识别,主要是从景观基因的角度进行的。区域景观基因成为判断传统聚落景观区的核心要素。通常情况下,传统聚落景观基因的判别,可以重点从心理要素、生态要素、美学要素、环境要素、文化要素、时序要素等6 个方面入手。     

Characteristics of dry-wet abrupt alternation events in the middle and lower reaches of the Yangtze River Basin and the relationship with ENSO

During recent decades, more frequent flood-drought alternations have been seen in China as a result of global climate change and intensive human activities, which have significant implications on water and food security. To better identify the characteristics of flood-drought alternations, we proposed a modified dry-wet abrupt alternation index (DWAAI) and applied the new method in the middle and lower reaches of the Yangtze River Basin (YRB-ML) to analyze the long-term spatio-temporal characteristics of dry-wet abrupt alternation (DWAA) events based on the daily precipitation observations at 75 rainfall stations in summer from 1960 to 2015. We found that the DWAA events have been spreading in the study area with higher frequency and intensity since 1960. In particular, the DWAA events mainly occurred in May and June in the northwest of the YRB-ML, including Hanjiang River Basin, the middle reaches of the YRB, north of Dongting Lake and northwest of Poyang Lake. In addition, we also analyzed the impact of El Niño Southern Oscillation (ENSO) on DWAA events in the YRB-ML. The results showed that around 41.04% of DWAA events occurred during the declining stages of La Niña or within the subsequent 8 months after La Niña, which implies that La Niña events could be predictive signals of DWAA events. Besides, significant negative correlations have been found between the modified DWAAI values of all the rainfall stations and the sea surface temperature anomalies in the Nino3.4 region within the 6 months prior to the DWAA events, particularly for the Poyang Lake watershed and the middle reaches of the YRB. This study has significant implications on the flood and drought control and water resources management in the YRB-ML under the challenge of future climate change.     

中国东部植被NDVI对气温和降水的时空响应(英文)

Temporal and spatial response characteristics of vegetation NDVI to the variation of temperature and precipitation in the whole year,spring,summer and autumn was analyzed from April 1998 to March 2008 based on the SPOT VGT-NDVI data and daily temperature and precipitation data from 205 meteorological stations in eastern China.The results indicate that as a whole,the response of vegetation NDVI to the variation of temperature is more pronounced than that of precipitation in eastern China.Vegetation NDVI maxi...     

贡嘎山东坡亚高山不同林地土壤水分特性与生态环境效应

森林土壤水分特性，包括水分的渗透与蒸发、保持与贮存等对森林生态环境都有重要意义。本文研究了长江上游贡嘎山亚高山不同森林类型土壤的水分特征及其生态环境作用，结果表明：成熟林、过熟林土壤在储水、渗透、容水、蒸发和持水特性等多数方面利于保持和改善生态环境，次生或林分单一森林类型次之，林木皆伐后最差。研究区以成熟林和过熟林为主，生态环境保护较好。尽管该区与长江上游其它地区一样同具自然地理条件差、生态环境脆弱的特征，但由于该区森林植被和环境得到了有效保护，土壤水分特性好，促进了森林生态系统的良性循环，生态环境问题得到进一步改善。