基于色觉异常人群的地图色彩设计研究进展     

钱梦茹  梁栋栋  吴旭 《测绘通报》2017,(1):5-11

在梳理国内外关于色觉异常人群的研究论文的基础上,从研究内容、研究方法等方面对国内外近年来有关色觉异常者的研究文献作了系统分析,发现国内外的研究主要集中在以下4个方面：①通过基本色的研究揭示非色彩的线索对色觉异常者描述和识别颜色起到作用;②对于色彩偏好的研究发现色觉异常者的颜色偏好与颜色情感相关;③根据色觉异常人群的视觉特征,结合图像转换算法,研究了无障碍色彩设计系统;④对于色觉异常人群的视觉色彩,利用图像模拟算法模拟校正色觉异常人群所看到的图像,进而识别图像信息。  相似文献   

辽东湾海洋溢油风险区划及防范对策研究          下载免费PDF全文

朱容娟  杨建军  宫云飞  兰冬东  鲍晨光  李冕 《海洋开发与管理》2017,34(9):95-99

海洋溢油风险区划是海洋溢油风险管理的重要手段,科学合理的风险区划可为预防和减少事故的发生提供管理依据。文章在海洋溢油风险系统研究和溢油污染事故机理分析的基础上,建立了辽东湾海洋溢油风险区划指标体系和风险量化模型,结合GIS空间分析方法,获得了辽东湾海洋溢油风险区划图。在分析辽东湾海洋溢油风险区主导因子和风险特征的基础上,提出了不同风险区的防范对策,为区域海洋溢油风险管理提供了决策依据。  相似文献   

GRACE卫星观测到的尼泊尔8.1级地震前后的重力变化     

瞿伟  安东东  薛康  张勤  王庆良  王栋 《大地测量与地球动力学》2017,37(12):1214-1218

利用GRACE卫星重力资料,计算尼泊尔地震震中及周缘重力和地表密度时空变化,并获取震源域特征点重力变化时间序列。结果表明,青藏高原内部、印度北部及华南块体东侧重力以增加为主,喜马拉雅与缅甸弧形带重力呈逐年减少趋势;尼泊尔地震发生在正负重力变化梯度带上,且重力变化在2015年具有明显的时间分段性特征,1~3月及地震发生的4月重力均以减小为主,5~9月以增加为主,12月以后以减小为主逐渐恢复;特征点时序揭示震源域重力呈长期减少趋势,并在2013~2016年呈现出“增加-减少-增加-发震-减小”的变化特征;地表密度变化较好地反映出地表质量迁移与重力变化的关系,为进一步理解尼泊尔地震的大陆动力学机制提供参考。  相似文献   

西昆仑山库地蛇绿岩的特征及其构造意义   总被引：17，自引：0，他引：17       下载免费PDF全文

杨树锋  贾承造 《地质科学》1999,34(3):281-288

库地蛇绿岩套由下部超镁铁质岩、辉长岩、幔源型花岗岩和上部基性火山岩、复理石等成分构成,形成于震旦纪-寒武纪。通过基性的辉长岩、玄武岩的矿物学、岩石学和地球化学研究得出,辉长岩表现出与典型蛇绿岩套中的堆晶辉长岩的特征相一致;而玄武岩则与大洋中脊玄武岩的特征一致,认为该蛇绿岩套是形成于洋中脊的蛇绿岩套。结合库地岛弧花岗岩的特征,提出塔里木盆地南缘在震旦纪-早古生代时期存在一个广阔的大洋,这一大洋在志留纪末期关闭。  相似文献   

流滑型窝崩水流结构特征及其变化规律          下载免费PDF全文

张幸农  牛晨曦  假冬冬  应强 《水科学进展》2020,31(1):112-119

针对长江中下游河段流滑型窝崩,进行水槽概化模拟试验,依据精细的流场观测数据,分析窝塘附近水流结构特征及变化规律,为探索此类崩岸力学机制奠定基础。结果表明,窝塘附近水流结构可分为口外主流区、口门涡流区和窝塘回流区三大区域。随着窝崩发展,三大区域内水流结构也随之产生变化。口外主流区基本为明渠弯道水流,有明显环流特征;口门涡流区呈现长条形态,其内存在多个大小、形态、位置和强度变化的涡旋,总体规律随主流快速下移不断破碎或分解,口门上、下两端水流呈明显三维特征且脉动性很强,水面波动剧烈;窝塘回流区内为典型空腔回流,随窝崩发展,其范围扩大,中心下移,形态由椭圆形趋向圆形,强度呈现增强-减弱-稳定的趋势。  相似文献   

不同含水率条件下花岗岩脆性特征评价指标研究     

曹洋兵  陈玉华  黄真萍  刘成禹  邱冬冬 《工程地质学报》2020,28(1):29-38

准确评价花岗岩在不同含水率条件下的脆性特征对此类工程岩体稳定性评价具有重要的意义。总结国内外现有岩石脆性评价指标,着重对基于应力-应变曲线特征的指标适用性和准确性进行详细分析和讨论,结合单轴压缩条件下花岗岩脆性特征随含水率增加而逐渐降低的试验规律,指出目前常用的基于应力-应变曲线特征的指标难以全面准确反映不同含水率花岗岩脆性特征。基于此,综合考虑全过程应力-应变曲线及峰后破坏时间,应用峰值应变表征峰前脆性特征、峰后应力跌落速率及应变增长速率表征峰后脆性特征,由此提出一种能全面反映花岗岩变形破坏全过程的脆性评价新指标Bd。经试验证实,新指标Bd能够准确地反映出花岗岩在不同含水率条件下的脆性变化趋势,相比其他脆性评价指标具有一定优越性。研究成果对丰富和改进现有的岩石脆性评价指标具有一定的参考意义和价值。  相似文献   

Influence of below-cloud evaporation on stable isotopes of precipitation in the Yellow River source region     

Linlin Ye  Guofeng Zhu  Longhu Chen  Dongdong Qiu  Yinying Jiao  Rui Li  Siyu Lu  Jiangwei Yang 《水文研究》2024,38(1):e15064

The study of below-cloud evaporation effects under clouds in the Yellow River source region is of great significance for regional water resource generation as well as for water resource security in the arid and semi-arid regions of northern China. In this study, we quantitatively assessed the evapotranspiration effect in the Yellow River source region from March to November based on the improved Stewart model. The study concluded that: (1) below-cloud evaporation was slightly higher in summer than in other seasons (residual fractions of raindrop evaporation were 80.57% in summer, 81.12% in spring, and 84.2% in autumn, respectively); and (2) sub-cloud evaporation diminishes with increasing altitude (residual fractions of raindrop evaporation were 83.09% in the western part of the area, 81.82% in the central part of the area, and 81.36% in the eastern part of the area, respectively). (3) The total linear index between study areas f and ∆d is 2.24, where f > 95%, it is 1.19; that is, the evaporation of raindrops increases by 1% and the reduction in the excess of mercury by about 2‰. (4) Local meteorological factors (temperature, precipitation, and relative humidity) and raindrop diameter have a cross-influence on below-cloud evaporation, with relative humidity having the most significant effect, with the highest correlation coefficient of 3.03 when relative humidity is less than 70%. The results of the study can provide a parameter basis for hydrological and climatic models in the Yellow River Basin.  相似文献   

Mechanisms of isotopic control of precipitation in the Yellow River source region     

Linlin Ye  Xinrui Lin  Guofeng Zhu  Yuwei Liu  Dongdong Qiu  Wenhao Zhang  Jiawei Liu  Siyu Lu 《水文研究》2024,38(2):e15087

The study of water vapour sources and water cycle patterns in the Yellow River source region is of great significance for ensuring water resource security in the arid and semi-arid regions of northern China. We established a precipitation stable isotope observation system in the Yellow River source region for three consecutive years (2020–2022), systematically analysed the spatial and temporal distribution characteristics of precipitation stable isotopes ²H and ¹⁸O in the Yellow River source region and their interrelationships with environmental factors and topography, and explored the regional water vapour transport pathways by using the HYSPLIT model and combining with the global reanalysis data. The results show that: (1) the δ¹⁸O and δ²H values of precipitation in the Yellow River source region follow the seasonal pattern, with the first half of the year being richer than the second half of the year; (2) the spatial variations of δ¹⁸O of precipitation in the Yellow River source region show a low in the southwest and a high in the northeast; (3) the water vapour source in the source area is basically stable, and the complex transport paths and the cross-effects of the local factors determine the stable isotope characteristics of the water, and the stable isotope characteristics of the water are determined by the cross-effects of the local factors, because the source of the water vapour and the local factors such as the height will not change significantly in the short term. Since the source of water vapour and local elevation factors will not change significantly in the short term, the precipitation pattern in the source area of the Yellow River can be considered to be basically stable.  相似文献   

Seismic collapse simulation of existing masonry buildings with different retrofitting techniques     

Ge Dongdong  Du Chunbo  Miao Qisong  Chen Xi 《地震工程与工程振动(英文版)》2021,20(1):127-139

Masonry buildings are primarily constructed out of bricks and mortar which become discrete pieces and cannot sustain horizontal forces created by a strong earthquake.The collapse of masonry walls may cause significant human casualties and economic losses.To maintain their integrity,several methods have been developed to retrofit existing masonry buildings,such as the constructional RC frame which has been extensively used in China.In this study,a new method using precast steel reinforced concrete(PSRC)panels is developed.To demonstrate its effectiveness,numerical studies are conducted to investigate and compare the collapse behavior of a structure without retrofitting,retrofitted with a constructional RC frame,and retrofitted with external PSRC walls(PSRCW).Sophisticated finite element models(FEM)were developed and nonlinear time history analyses were carried out.The results show that the existing masonry building is severely damaged under occasional earthquakes,and totally collapsed under rare earthquakes.Both retrofitting techniques improve the seismic performance of existing masonry buildings.However,it is found that several occasional earthquakes caused collapse or partial collapse of the building retrofitted with the constructional RC frame,while the one retrofitted by the proposed PSRC wall system survives even under rare earthquakes.The effectiveness of the proposed retrofitting method on existing masonry buildings is thus fully demonstrated.  相似文献   

Ordovician tectonic transition from passive margin into peripheral foreland in the southern Ordos: A diagnostic insight into the closure of Erlangping Ocean between the North Qinling Arc and North China Block     

Jiaopeng Sun  Yunpeng Dong  Qiang Chen  Lei Yang  Wenhou Li  Dongdong Zhang  Qian Zhang 《Basin Research》2023,35(1):336-362

Achieving a reliable closure time of a back-arc ocean is an essential aspect in studies on detailed tectonic processes of an active continental margin and arc–continent collision. This is particularly the case for the northern Qinling Orogen, which records the accretion of the North Qinling Arc (NQA) onto the North China Block (NCB) after the Erlangping back-arc ocean closure. Sedimentological, petrological and geochronological signatures from the Ordovician successions in the southern Ordos reveal a tectonic transition from passive continental margin to peripheral foreland in the southern NCB at the beginning of Katian. Sedimentological and geochronological investigations reveal an abrupt shift of accelerating basin subsidence and deepening at the earliest Katian, separating ca. 300-m-thick shallow-marine carbonate shelf assemblages from overlying ca. 2000-m-thick deep-water carbonate slope and turbidite associations. Zircon age spectra of the Katian turbidites are characterized by early-Palaeozoic and Neoproterozoic age clusters, which are different from those of the Middle Ordovician quartz arenites sourced merely from the NCB basement. Instead, these age patterns match well with those of the coeval successions in the northern NQA, indicating a spatially linked abyssal deposystem. Stratigraphic architecture deciphers a typical foreland basin geometry, involving, from south to north, northward-propagating turbiditic wedge, northward-backstepping carbonate slope and progressively shoaling carbonate platform, embodying foredeep, forebulge and backbulge, respectively. These characteristics of basin-fill evolution reflect the northward migration of the flexural wave as a dynamic response to the northward expansion of the thickened NQA thrust wedge. Together with the other geological and geochronological data, our new insights indicate a southward subduction polarity of the Erlangping back-arc oceanic crust followed by its termination at ca. 450 Ma, which was earlier than that of the main Proto-Tethyan Shangdan Ocean between the NCB and South China Block. Our new data provide an updated view of the complex history of the Proto-Tethys closure during the Gondwana assembly.  相似文献