基于长短期记忆神经网络的风速超短期快速滚动预报技术

利用甘肃省某风电场2017—2020年测风数据,基于长短期记忆神经网络(LSTM)模型,通过评估不同输入数据和模型时间窗口长度下的预报精度,设计一套适用于风电场的风速超短期快速滚动预报方案。结果表明：通过输入不同的特征变量,在风速的超短期(未来4 h内)预报中,风速自身变化起主导作用,模型输入变量中只加入各高度层的风速能得到更好的模拟效果。通过评估LSTM模拟时间窗口长度L对模拟效果的影响,当时间窗口长度L≤24 h时,模拟效果较好,说明超短期风速变化主要和风速自身临近时刻的变化有关;当L>24 h时,模拟效果快速下降,说明过长的L会削弱模拟能力,降低模拟精度。通过分析LSTM在未来4 h内的风速模拟能力,发现随着预报时长的增加,模拟精度逐步下降,但在未来2 h内的风速均方根误差RMSE均小于2 m·s^-1,结果较为理想,且该方法对计算资源要求不高,经济实用性强,在业务中具有较高的应用潜力。     

中国东部土壤温度、湿度变化的长期趋势及其与气候背景的联系

利用1971—2000年中国722站逐月的土壤温度资料和1981—1998年178站逐旬的土壤湿度观测资料,分析了中国东部土壤温度、湿度变化的长期趋势及其与气温、降水变化的关系。结果表明：①我国东部土壤温度的变化在年际—年代际时间尺度上存在明显的区域性差异,其中东北地区表现为持续上升型,而西北东部—华北、江淮和西南—华南地区均为先降后升型;②1970—2000年代,土壤温度的变化在东北以及西北东部—华北地区有显著的上升趋势,而在江淮和西南—华南地区,总体而言变化趋势不显著。此外,1980—1990年代,各区域土壤湿度的变化趋势均不显著;③在年际—年代际尺度上,各区域土壤温度和气温的变化具有显著的正相关关系,而土壤湿度与土壤温度的变化普遍呈负相关关系,其中尤以西北东部—华北地区最为显著。而在较长的时间尺度上,土壤湿度与降水的变化仍然存在较好的正相关关系。     

京张地区区域地壳稳定性评价

在野外调查和广泛收集资料的基础上,分析了控制和影响京张地区区域地壳稳定性的主要因素及内外动力地质的耦合作用。选取活动断裂、地震活动性和深部地球物理等因素,同时选取工程岩组、地形地貌与地表地质灾害等11个因素作为评价因子,并对评价因子进行了分类赋值。采用多因素加权叠加分析方法,建立了区域地壳稳定性评价模型,基于GIS平台对京张地区的区域地壳稳定性进行了定量化评价,将研究区划分为稳定区、次稳定区、次不稳定区和不稳定区4个等级。依据区域地壳稳定性评价结果,为京张高速铁路、云顶滑雪场、石京龙滑雪场的建设和运营提出相关建议,为京张地区国土规划提供了基础依据。      

汶川M_S8.0地震对甘肃陇东地区的破坏影响与特征分析

在汶川MS8.0地震后甘肃陇东地区的详细灾害调查基础上,对该区地震破坏进行了分类研究,给出了各种建筑物及工程结构的破坏程度及破坏特征.结合该区独特的地质地理环境对产生地震破坏的原因进行了分析.认为该区地震破坏相对严重的原因除与建筑物本身质量及结构有关外,还与远震和地形影响的长周期效应及持时较长有关.     

SH波入射下圆弧状沉积盆地地震反应瞬态解析解计算

地震波散射问题的解析解是研究局部场地、地形、盆地等不规则地层结构对地震动参数放大效应影响的重要理论工具.现有解析解大部分在频域内给出,无法直接用于研究不规则地层结构对地震动峰值、反应谱等参数的放大效应.本文基于平面SH波入射下圆弧状沉积盆地动力响应宽频带稳态解析解,通过Fourier变换,获取瞬态响应解析解.基于此,研...     

泰国北部三叠系Lampang群Doi Long组的有孔虫组合与沉积环境

A rich foraminiferal assemblage, consisting of abundant Aulotortus sinuosus and A. tumidus in association with Lamelliconus multispirus, Endoteba ex gr. controversa, E. ex gr. badouxi, Endotebanella kocaeliensis, Endotriada tyrrhenica, Endotriadella wirzi, Malayspirina fontainei, Ammobaculites rhaeticus, Diplotremina astrofimbriata, Agathammina austroalpina, and others, was found in the Doi Long Formation of the Triassic Lampang Group, Northern Thailand. These foraminifers suggest that the formation is referable to the Carnian (early Late Triassic), which is consistent with the age estimated by ammonoids. In microfacies, peloidal grainstone, bioclastic grainstone, sponge-microbial boundstone, and oolitic grainstone were recognized in the Doi Long Formation. Based on microfacies, three depositional facies, the lagoon facies, reef facies, and shoal facies, are recognized in this formation. These lines of evidence are suggestive that the Doi Long Formation was deposited in a reef or bank setting rather than a ramp setting.     

Long period variations of the motion of a satellite due to non-resonant tesseral harmonics of a gravity potential

The main effects of tesseral harmonics of a gravity potential expansion on the motion of a satellite, are short period variations as well as long period variations due to resonances. However, other smaller long period and secular variations can arise from interactions between tesseral terms of the same order. The analytical integration of these effects is developed, using numerical evaluation of Kaula eccentricity and inclination functions. Examples for some Earth's geodetic satellites show that secular effects can reach a few decameters per year. The secular variations can even reach several hundred of meters per year for the Mars natural satellite Phobos.     

冷空气对夏季高原涡移出高原后长久与短期活动影响的对比分析

本文利用NCEP/NCAR-FNL再分析资料、历史天气图和青藏高原低涡切变线年鉴,通过分析1998~2016年高原涡活动情况,对在高原以东活动时间大于96 h的高原涡（长持续涡）和在高原以东活动时间不大于30 h的高原涡（短持续涡）,进行了环流与冷空气活动特征与位涡诊断的对比分析,得出了长、短持续涡的环境场、冷空气活动特征,揭示了冷空气活动、高空锋区对长、短持续涡的影响。结果表明:（1）长持续涡移出高原后是在受较明显冷空气影响情况下加强并持续的,短持续涡则没有明显受冷空气影响。长持续涡所处的低槽较深,槽后的冷温度槽较明显,副热带高压（简称副高）偏南;短持续涡处在分裂槽中,有冷舌,副高偏北;说明影响低涡活动的天气系统强,槽后的冷温度槽明显,副高偏南是低涡能较长时间持续的重要环流条件。（2）长持续涡不仅受到较强冷平流的影响,还处在有狭长的干冷与暖湿空气相遇的地带,使涡区极易产生对流不稳定和低涡扰动,利于低涡加强并持续,短持续涡则远不及长持续涡。（3）长持续涡移出高原后受两个不同方向冷空气影响,涡区内一般伴有两个高位涡中心区,而短持续涡的只有一个高位涡中心区,且位涡值比长持续涡小,长持续涡活动过程中的斜压性也比短持续涡强。另外,长持续涡活动过程中相应的高空急流较强,在增强、东伸、南压作用下,造成200 hPa高空有高位涡下传到低涡,而短持续涡所伴的西风急流平直、弱,造成了短持续涡只受到400 hPa高位涡下传的影响。（4）冷空气影响高原涡维持的作用有:使影响高原涡活动的天气系统加强;使高原涡斜压性增强、对流不稳定增强;使高空有高位涡下传至低涡附近层次,造成低涡区域正位涡异常,垂直涡度发展,低涡加强。     

Exploring determinants of the extent of long distance commuting in Australia: accounting for space

Previous research exploring the impacts of long distance commuting (LDC) or, more generally, mining on host regions, struggles to explain the variability of these impacts over time and across space. This article argues that spatial effects should be accounted for explicitly in order to improve the predictive power of contemporary research. We study the extent of LDC in a region in a spatial model disaggregating Australia into 325 subregions. We find evidence that space is an important factor in explaining the extent of LDC in a region, which challenges the validity of studying LDC impacts on host regions in isolation. With regards to the determinants of the extent of LDC, we find that residential attractiveness of a region influences the extent of LDC in a region; the size of the pool of unemployed in a region does not.     

Long-term variation of solar UVB (290–330 nm) observed at the earth's surface

During solar cycle 21 (1976–86), the primary solar irradiance at 300 nm was steady during 1980–82 and thereafter decreased until 1986 by only 2–3%. The stratospheric ozone in middle latitudes had a QBO of 3–4% in this interval but the long-term ozone trend was less than 3% per decade, which could result in a UVB increase of only 5–6% per decade. Thus, the combined effect of changes in primary solar irradiance and ozone changes could be an increase of 5–6% in UVB, observed at ground during 1977–81 and a steady level during 1981–86. During 1976–86, the average cloudiness changed by less than 5% indicating UVB changes of 5% or less on this count. The aerosol level was almost constant during 1976–82 and increased abruptly in 1982 due to the E1 Chichon eruption and decayed slowly unitl 1986. Thus, due to aerosols only, the UVB was expected to be constant during 1976–82, to decrease sharply in 1982 and to recoup slowly thereafter.Measurements of clear-sky solar UVB at ground made at Jungfraujoch (Swiss Alps, 47°N, 8°E) during 1981–89 and at Rockville, USA (39°N, 77°W) were not comparable between themselves and did not follow the above expected patterns. Neither did the all-day R-B meter UVB measurements at Philadelphia, USA (40°N, 75°W) and Minneapolis, USA (45°N, 93°W). We suspect that some of these measurements are erroneous. This needs further detailed scrutiny.