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Assessing Drought Conditions in Cloudy Regions Using Reconstructed Land Surface Temperature 认领
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作者 Shiqi YANG Dejun ZHANG +2 位作者 Liang SUN Yongqian WANG Yanghua GAO 《气象学报:英文版》 SCIE CSCD 2020年第2期264-279,共16页
Temperature vegetation dryness index(TVDI)in a triangular or trapezoidal feature space can be calculated from the land surface temperature(LST)and normalized difference vegetation index(NDVI),and has been widely appli... Temperature vegetation dryness index(TVDI)in a triangular or trapezoidal feature space can be calculated from the land surface temperature(LST)and normalized difference vegetation index(NDVI),and has been widely applied to regional drought monitoring.However,thermal infrared sensors cannot penetrate clouds to detect surface information of sub-cloud pixels.In cloudy areas,LST data include a large number of cloudy pixels,seriously degrading the spatial and temporal continuity of drought monitoring.In this paper,the Remotely Sensed Daily Land Surface Temperature Reconstruction model(RSDAST)is combined with the LST reconstructed(RLST)by the RSDAST and applied to drought monitoring in a cloudy area.The drought monitoring capability of the reconstructed temperature vegetation drought index(RTVDI)under cloudy conditions is evaluated by comparing the correlation between land surface observations for soil moisture and the TVDI before and after surface temperature reconstruction.Results show that the effective duration and area of the RTVDI in the study area were larger than those of the original TVDI(OTVDI)in 2011.In addition,RLST/NDVI scatter plots cover a wide range of values,with the fitted dry–wet boundaries more representative of real soil moisture conditions.Under continuously cloudy conditions,the OTVDI inverted from the original LST(OLST)loses its drought monitoring capability,whereas RTVDI can completely and accurately reconstruct surface moisture conditions across the entire study area.The correlation between TVDI and soil moisture is stronger for RTVDI(R=-0.45)than that for OTVDI(R=-0.33).In terms of the spatial and temporal distributions,the R value for correlation between RTVDI and soil moisture was higher than that for OTVDI.Hence,in continuously cloudy areas,RTVDI not only expands drought monitoring capability in time and space,but also improves the accuracy of surface soil moisture monitoring and enhances the applicability and reliability of thermal infrared data under extreme conditions. 展开更多
关键词 LAND SURFACE TEMPERATURE RECONSTRUCTION Remotely Sensed Daily LAND SURFACE TEMPERATURE RECONSTRUCTION model(RSDAST) TEMPERATURE vegetation DRYNESS index(TVDI) soil moisture drought
不同温度对草地贪夜蛾幼虫和蛹生长发育的影响 认领 被引量:2
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作者 赵琳超 廖用信 +2 位作者 陈壮美 刘航 王星 《湖南师范大学自然科学学报》 CAS 北大核心 2020年第1期41-47,共7页
为明确温度对草地贪夜蛾生长发育的影响,测定了6个温度(18,21,24,27,30和33℃)条件下草地贪夜蛾幼虫和蛹的发育历期、蛹重和存活率等指标,计算出各虫态的发育起点温度、有效积温和各温度条件下的发育速率。结果表明:在18~33℃范围内,草... 为明确温度对草地贪夜蛾生长发育的影响,测定了6个温度(18,21,24,27,30和33℃)条件下草地贪夜蛾幼虫和蛹的发育历期、蛹重和存活率等指标,计算出各虫态的发育起点温度、有效积温和各温度条件下的发育速率。结果表明:在18~33℃范围内,草地贪夜蛾幼虫和蛹的发育历期均随着温度的升高而逐渐缩短,发育速率逐渐加快,其生长发育的最适宜温度范围为24~33℃;幼虫和蛹的发育起点温度分别为10.61±3.19℃和13.29±1.34℃,有效积温分别为183.19±9.96 d·℃和134.83±13.71 d·℃。该虫的蛹重随着温度的升高呈先升高后降低的变化趋势,在21℃条件下,其蛹重达到最大值251.91±11.19 mg。 展开更多
关键词 草地贪夜蛾 温度 生长发育 发育起点温度 有效积温
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河北省舍饲绵羊的热应激评价及温湿参数与羊生理指标的相关性研究 认领
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作者 赵娟娟 冯曼 +6 位作者 孙新胜 卢冬梅 王超 赵寿培 车大璐 李雪梅 高玉红 《畜牧兽医学报》 CAS CSCD 北大核心 2020年第6期1342-1353,共12页
本研究旨在评价河北省三大区域(冀北燕山、太行山区和冀中南平原)羊场夏季绵羊的热应激程度,并分析温热环境参数与绵羊个体生理指标的相关性,为改善羊舍环境提供理论依据。选择3个区域12个规模化羊场,自动检测并记录夏季羊舍的环境温度... 本研究旨在评价河北省三大区域(冀北燕山、太行山区和冀中南平原)羊场夏季绵羊的热应激程度,并分析温热环境参数与绵羊个体生理指标的相关性,为改善羊舍环境提供理论依据。选择3个区域12个规模化羊场,自动检测并记录夏季羊舍的环境温度和相对湿度2个月,同时检测各场绵羊的直肠温度和呼吸频率。结果表明,冀北燕山、太行山区和冀中南平原的羊舍日均温度分别达24.3、28.5和28.7℃,温湿指数(THI)分别达72.40、79.91和79.47,冀北燕山区域绵羊正遭受轻度热应激,而太行山区和冀中南平原地区的绵羊遭受中度甚至重度热应激,可见,夏季河北省舍饲绵羊的热应激防控需要引起关注,加强夏季的防暑降温措施刻不容缓。从绵羊个体生理指标看,3个区域绵羊的直肠温度范围为39.1~39.8℃,呼吸频率为42~114次·min^-1,直肠温度与环境温度、THI之间均未表现出显著相关关系(P>0.05),但与相对湿度间表现出显著的线性负相关关系(P<0.05,r=0.60);呼吸频率与环境温度、THI之间表现出极显著正相关关系(P<0.01,r=0.84;P<0.01,r=0.87),与相对湿度间未表现出显著相关关系(P>0.05)。因此,通过羊舍温湿参数和THI的测定可以推断绵羊的个体生理状况,对实际生产中舍饲羊热应激的预防及相关疾病的诊断提供依据。 展开更多
关键词 绵羊 温度 相对湿度 温湿指数 呼吸频率 直肠温度
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Elevational patterns of temperature and humidity in the middle Tianshan Mountain area in Central Asia 认领
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作者 Gheyur GHEYRET Anwar MOHAMMAT TANG Zhi-yao 《山地科学学报:英文版》 SCIE CSCD 2020年第2期397-409,共13页
The vertical distribution of vegetation types along an elevational gradient in mountain areas largely depends on the elevational changes in air temperature and humidity. In this study, we presented the seasonal and di... The vertical distribution of vegetation types along an elevational gradient in mountain areas largely depends on the elevational changes in air temperature and humidity. In this study, we presented the seasonal and diurnal variations in the elevational gradients of air temperature and humidity on the southern and northern slopes in the middle Tianshan Mountain Range using data collected throughout the year via HOBO data loggers. The measurements were conducted at 12 different elevations from 1548 to 3277 m from September 2004 to August 2005. The results showed that the annual mean air temperature decreased along the elevational gradients with temperature lapse rates of(0.71±0.20)°C/100 m and(0.59±0.05)°C/100 m on the northern and southern slopes, respectively. The annual mean absolute humidity significantly decreased with increasing elevation on the northern slope but showed no significant trend on the southern slope. The annual mean relative humidity did not show a significant trend on the northern slope but increased with increasing elevation on the southern slope. The mean air temperature lapse rate exhibited significant seasonal variation, which is steeper insummer and shallower in winter, and this value varied between 0.37°C/100 m and 0.75°C/100 m on the southern slope and between 0.30°C/100 m and 1.02°C/100 m on the northern slope. The mean absolute and relative humidity also exhibited significant seasonal variations on both slopes, with the maximum occurring in summer and the minimum occurring in winter or spring. The monthly diurnal range of air temperature on both slopes was higher in spring than in winter. The annual range of air temperature on the southern slope was higher than that on the northern slope. Our results suggest that significant spatiotemporal variations in humidity and temperature lapse rate are useful when analyzing the relationships between species range sizes and climate in mountain areas. 展开更多
关键词 TEMPERATURE LAPSE rate Absolute humidity Relative humidity ANNUAL RANGE of TEMPERATURE DIURNAL RANGE of TEMPERATURE HOBO data loggers
草地贪夜蛾在不同温度条件下的生长发育特性 认领
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作者 张红梅 尹艳琼 +5 位作者 赵雪晴 李向永 王燕 刘莹 陈福寿 谌爱东 《环境昆虫学报》 CSCD 北大核心 2020年第1期52-59,共8页
为掌握草地贪夜蛾的主要生物学特性,本文在5个恒温条件下:20℃、25℃、28℃、32℃和35℃,采用玉米苗作为饲料,测定了不同虫态的发育历期、繁殖力、发育起点温度和有效积温。结果表明:在20~35℃温度条件下,草地贪夜蛾的发育历期随着温度... 为掌握草地贪夜蛾的主要生物学特性,本文在5个恒温条件下:20℃、25℃、28℃、32℃和35℃,采用玉米苗作为饲料,测定了不同虫态的发育历期、繁殖力、发育起点温度和有效积温。结果表明:在20~35℃温度条件下,草地贪夜蛾的发育历期随着温度的升高逐渐下降,完成一个世代发育历期在23.0~48.3 d;其中,卵、幼虫、蛹、成虫和世代发育起点温度分别为:12.70℃、11.11℃、11.01℃、5.65℃和9.21℃,有效积温分别为:39.40日·度、201.25日·度、134.12日·度、171.06日·度和636.53日·度;20~32℃是卵、幼虫、蛹和成虫产卵的适宜温度,15℃、35℃恒温条件下不适宜草地贪夜蛾的生长发育。根据本试验测定的发育起点温度与有效积温,推测草地贪夜蛾在滇中、滇西、滇南、滇东南、滇西南、滇东北、滇西北年发生世代分别为2.18~8.59代、2.28~10.15代、3.43~12.13代、3.15~8.46代、2.75~9.39代、1.38~6.87代、1.11~6.72代。 展开更多
关键词 草地贪夜蛾 温度 发育历期 起点温度 有效积温
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文章速递1880年以来地球陆地-海洋温度指数中的太阳黑子活动周期研究 认领
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作者 郭纪君 郭治龙 王宁练 《高原气象》 CSCD 北大核心 2020年第4期851-858,共8页
地球表面气温波动存在多种周期,太阳辐射是地球气候系统的外部驱动力,其对地球表面气温具有一定的调制作用。利用Morlet复值小波变换法分析了1880以来地球陆地-海洋温度指数的周期特征,识别出地球陆地-海洋温度指数具有22年周期。在周... 地球表面气温波动存在多种周期,太阳辐射是地球气候系统的外部驱动力,其对地球表面气温具有一定的调制作用。利用Morlet复值小波变换法分析了1880以来地球陆地-海洋温度指数的周期特征,识别出地球陆地-海洋温度指数具有22年周期。在周期、相位、振幅等基础上,对地球陆地-海洋温度指数和太阳黑子的22年周期分别进行正弦函数拟合,得出地球陆地-海洋温度指数的22年磁周期与太阳黑子数量的22年周期呈正相关关系;进一步分析表明,太阳黑子数量的22年磁周期可能是地球陆地-海洋温度指数22年周期的驱动力。在99%置信水平下,太阳黑子数量22年周期的振幅约为0.21℃,对全球变暖的评估具有重要影响,为定量研究全球气候及其驱动机制提供了新的证据。 展开更多
关键词 气温 太阳黑子 全球变暖 气温预测 小波分析
文章速递无线物联网测温技术在供用电系统应用的可行性研究与分析 认领
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作者 尉言龙 《石化技术》 CAS 2020年第8期41-42,共2页
采用物联网无线测温技术将温度数据通过传感器实时采集和分析处理,及时将异常信息通过短信、报警铃声等方式发布给运行维护人员,进行检查维护,确保供配电系统的正常有效运行。
关键词 温度 无线物联网测温 分站
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Experimental study on the influence of temperature cycle on low-rank coal permeability 认领
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作者 ZOU JunPeng JIAO YuYong +1 位作者 RATHNAWEERA T D WANG Hao 《中国科学:技术科学英文版》 SCIE EI CAS CSCD 2020年第6期1055-1065,共11页
The formation temperature is a key factor affecting coalbed methane(CBM)migration in reservoirs.Both the prediction of CBM production and prevention of mine gas disasters require the understanding on the controlling m... The formation temperature is a key factor affecting coalbed methane(CBM)migration in reservoirs.Both the prediction of CBM production and prevention of mine gas disasters require the understanding on the controlling mechanism of temperature on coal permeability.We experimentally examined the evolution of permeability for natural low-rank coal samples under various stresses and cyclic temperature conditions.Apparent permeability and intrinsic permeability decrease significantly when the temperature increases and they only partially recover after the temperature returns.The permeability loss decreases greatly with the increasing number of temperature cycles.The permeability loss due to the rising temperature and the irreversible permeability loss for a whole temperature cycle decrease prominently with increasing confining stress.The impacts of swelling/shrinking of coal matrix,roughness of surface,pore compressibility and weakly bound water in coal on temperature sensitivity of coal permeability are investigated. 展开更多
关键词 low-rank coal PERMEABILITY temperature cycle temperature sensitivity
Finite deformation swelling of a temperature-sensitive hydrogel cylinder under combined extension-torsion 认领
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作者 M.SHOJAEIFARD M.BAGHANI 《应用数学和力学:英文版》 SCIE EI CSCD 2020年第3期409-424,共16页
The swelling behavior of a temperature-sensitive poly-N-isopropylacrylamide(PNIPAM) hydrogel circular cylinder is studied subjected to combined extension-torsion and varied temperature. In this regard, a semi-analytic... The swelling behavior of a temperature-sensitive poly-N-isopropylacrylamide(PNIPAM) hydrogel circular cylinder is studied subjected to combined extension-torsion and varied temperature. In this regard, a semi-analytical solution is proposed for general combined loading. A finite element(FE) analysis is conducted, subjecting a hydrogel cylinder to the combined extension-torsion and the varied temperature to evaluate the validity and accuracy of the solution. A user-defined UHYPER subroutine is developed and verified under free and constrained swelling conditions. The FE results illustrate excellent agreement with the semi-analytical solution. Due to the complexity of the problem, some compositions and applied loading factors are analyzed. It is revealed that for larger cross-linked density and larger ending temperature, the cylinder yields higher stresses and smaller radial swelling deformation. Besides, the radial and hoop stresses increase by applying larger twist and axial stretch. The hoop stresses intersect at approximately R/Rout = 0.58, where the hoop stress vanishes. Besides, the axial force has direct and inverse relationships with the axial stretch and the twist, respectively. However, the resultant torsional moment behavior is complex, and the position of the maximum point varies significantly by altering the axial stretch and the twist. 展开更多
关键词 extension-torsion of the circular cylinder temperature variation finite element(FE)analysis temperature-sensitive poly-N-isopropylacrylamide(PNIPAM)hydrogel semi-analytical solution
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Improvement of the electrical resistivity of epoxy resin at elevated temperature by adding a positive temperature coefficient BaTiO3-based compound 认领
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作者 滕陈源 周文俊 +4 位作者 周远翔 张灵 张云霄 周仲柳 李文鹏 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2020年第4期15-23,共9页
The DC electrical resistivity-temperature characteristic is an important property for insulating materials to operate at a high stress level.In order to improve the DC electrical resistivity at elevated temperature in... The DC electrical resistivity-temperature characteristic is an important property for insulating materials to operate at a high stress level.In order to improve the DC electrical resistivity at elevated temperature in a targeted way,a positive temperature coefficient(PTC)material(Ba Ti O3-based compound(BT60))was selected as the filler in this paper,whose electrical resistivity has a PTC effect when the temperature exceeds its Curie temperature.The BT60 was treated with hydrogen peroxide and(3-Aminopropyl)triethoxysilane.Epoxy composites with different loadings of BT60 fillers(0 wt%,0.5 wt%,and 2 wt%of epoxy)were prepared,denoted as EP-0,EP-0.5,and EP-2.It was shown that BT60 was able to maintain the DC breakdown strength when its loading was less than 2 wt%of epoxy.As the temperature exceeds 60°C,BT60 will compensate for the negative temperature coefficient effect of epoxy resin to some extent.The electrical resistivity of EP-2 was improved by 55%compared with that of neat epoxy at 90°C.It was found that the potential barrier at the grain boundary of BT60 and the deep traps in the interface between BT60 and the epoxy resin hinder the migration of carriers and thus increase the electrical resistivity of epoxy composite. 展开更多
关键词 epoxy resin positive TEMPERATURE coefficient BARIUM TITANATE based compounds resistivity-temperature characteristics TRAPS
中国中世纪气候异常期温度的多尺度变化特征及区域差异 认领
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作者 郝志新 吴茂炜 +2 位作者 刘洋 张学珍 郑景云 《地理学报:英文版》 SCIE CSCD 2020年第1期119-130,共12页
The Medieval Climate Anomaly(MCA,AD950-1250)is the most recent warm period lasting for several hundred years and is regarded as a reference scenario when studying the impact of and adaptation to global and regional wa... The Medieval Climate Anomaly(MCA,AD950-1250)is the most recent warm period lasting for several hundred years and is regarded as a reference scenario when studying the impact of and adaptation to global and regional warming.In this study,we investigated the characteristics of temperature variations on decadal-centennial scales during the MCA for four regions(Northeast,Northwest,Central-east,and Tibetan Plateau)in China,based on high-resolution temperature reconstructions and related warm-cold records from historical documents.The ensemble empirical mode decomposition method is used to analyze the time series.The results showed that for China as a whole,the longest warm period during the last 2000 years occurred in the 10th-13th centuries,although there were multi-decadal cold intervals in the middle to late 12th century.However,in the beginning and ending decades,warm peaks and phases on the decadal scale of the MCA for different regions were not consistent with each other.On the inter-decadal scale,regional temperature variations were similar from 950 to 1130;moreover,their amplitudes became smaller,and the phases did not agree well from 1130 to 1250.On the multi-decadal to centennial scale,all four regions began to warm in the early 10th century and experienced two cold intervals during the MCA.However,the Northwest and Central-east China were in step with each other while the warm periods in the Northeast China and Tibetan Plateau ended about 40-50 years earlier.On the multi-centennial scale,the mean temperature difference between the MCA and Little Ice Age was significant in Northeast and Central-east China but not in the Northwest China and Tibetan Plateau.Compared to the mean temperature of the 20th century,a comparable warmth in the MCA was found in the Central-east China,but there was a little cooling in Northeast China;meanwhile,there were significantly lower temperatures in Northwest China and Tibetan Plateau. 展开更多
关键词 China MULTI-SCALE VARIATIONS temperature MEDIEVAL CLIMATE ANOMALY
Study on Climate Changes for Flue-Cured Tobacco Growth in Chenzhou City of Hunan Province 认领
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作者 Xiangzhen Kong Decheng Li +2 位作者 Wujin Li Hongguang Li Yansong Xiao 《农业科学(英文)》 2020年第5期487-499,共13页
Chenzhou city is the most typical region of Nanling Hill Ecological Zone of flue-cured tobacco with of aroma style of burnt sweet and pure sweet in China and is the largest planting region of flue-cured tobacco in Hun... Chenzhou city is the most typical region of Nanling Hill Ecological Zone of flue-cured tobacco with of aroma style of burnt sweet and pure sweet in China and is the largest planting region of flue-cured tobacco in Hunan province. It is of significance to study the changes of climatic parameters with time because climate is the most important factor in determining the growth, yield and quality of flue-cured tobacco. In this study, the data of climatic parameters including cumulative sunshine hours(S), mean temperature (T) and cumulative precipitation (P)from 1952 to 2018 in Chenzhou were used to analyze their changes at the scales of year, whole field period and growing period of flue-cured tobacco. The results showed that at the scale of year, the cumulative S, mean T and cumulative P were ranged from 1029.0 h to 2072.1 h, from 17.1°C to 19.5°Cand from 897.1 mm to 2244.6 mm, with the means of 1449.7 h, 18.1°C and 1482.5 mm, respectively. At the scale of whole field period of flue-cured tobacco, the cumulative S, mean T and cumulative P were ranged from 298.1 h to 807.2 h, from 21.2°C to 23.9°C and from 416.7 mm to 1102.7 mm, with the means of 514.8 h, 22.3°C and 719.0 mm, respectively. At the scale of growing period of flue-cured tobacco, the annual cumulative S were ranged from 70.0 h to 257.2 h, from 77.3 h to 322.5 h and from 131.2 h to 300.3 h in the periods of rooting, flourishing and maturing with the means of 127.8 h, 190.4 h and 197.2 h, respectively. The mean temperatures were ranged from 14.2°C to 18.9°C, from 22.2°C to 26.1°C, and from 25.8°C to 29.6°C with the means of 16.4°C, 24.1°C and 28.0°C, respectively. The annual cumulative P were ranged from 69.9 mm to 553.9 mm, from 133.1 mm to 485.6 mm and from 46.4 mm to 356.8 mm in the periods of rooting, flourishing and maturing with the means of 262.5 mm, 299.9 mm and 153.9 mm, respectively. At the year scale, cumulative S annually decreased by 7.587 h, mean T annually increased by 0.02°C, while cumulative P changed irregularly with insig 展开更多
关键词 SUNSHINE Hours TEMPERATURE PRECIPITATION Flue-Cured TOBACCO Chenzhou
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钛合金表面热浸铝技术的研究进展及展望 认领
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作者 李勇 周青 +1 位作者 朱金波 张田 《成都航空职业技术学院学报》 2020年第2期67-70,共4页
钛合金表面热浸铝技术是将预处理过的钛合金零件在熔融铝液中浸没一定的时间,在钛合金表面形成镀层以强化表面的一种表面处理技术.本文综述了钛合金表面热浸铝梯度镀层的微观生长机理和组织成分;镀层对合金硬度、耐磨性及抗高温氧化性... 钛合金表面热浸铝技术是将预处理过的钛合金零件在熔融铝液中浸没一定的时间,在钛合金表面形成镀层以强化表面的一种表面处理技术.本文综述了钛合金表面热浸铝梯度镀层的微观生长机理和组织成分;镀层对合金硬度、耐磨性及抗高温氧化性的影响以及其他热浸铝工艺.分析了浸镀液的温度、浸镀时间及热扩散温度、时间对镀层组织和性能的影响.提出热浸铝+交变电磁场中凝固新方法的可行性. 展开更多
关键词 热浸铝 温度 高温氧化 电磁场
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A New Method for Predicting Wall Sticking Occurrence Temperature of High Water Cut Crude Oil 认领
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作者 Cui Yue Huang Qiyu +3 位作者 Zhang Yan Zhao Jiadi Zheng Haimin Cheng Xianwen 《中国炼油与石油化工:英文版》 SCIE CAS 2020年第2期56-63,共8页
In crude oil transportation, adhesion of oil on pipe wall can cause partial or total blockage of the pipe. This process is significantly affected by wall sticking occurrence temperature(WSOT). In this work, an efficie... In crude oil transportation, adhesion of oil on pipe wall can cause partial or total blockage of the pipe. This process is significantly affected by wall sticking occurrence temperature(WSOT). In this work, an efficient approach for estimating WSOT of high water-cut oil, which can agree well with the actual environment of multiphase transportation pipeline, is proposed. Based on the energy dissipation theory, it is possible to make comparison of average shear rates between the stirred vessel and the flow loop. The impacts of water content and shear rate on WSOT are investigated using the stirred vessel and the flow loop. Good agreement has been observed between the stirred vessel and the flow loop results with the maximum and the average absolute deviations equating to 3.30 °C and 2.18 °C, respectively. The development of gathering scheme can enjoy some benefits from this method. 展开更多
关键词 high water-cut oil wall sticking occurrence temperature adhesion energy dissipation low-temperature gathering
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Study of the Indicators of Climate Change in Mysore District, Karnataka, India 认领
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作者 Alaa Samy Hafez Megahed S. Srikantaswamy 《大气和气候科学(英文)》 2020年第2期159-167,共9页
The study aims to find out the changes of climate change parameters for Mysore district. To analyse the variations in climatic parameters like Rainfall and Temperature, data were used for a period of 1986-2016, and Hu... The study aims to find out the changes of climate change parameters for Mysore district. To analyse the variations in climatic parameters like Rainfall and Temperature, data were used for a period of 1986-2016, and Humidity data were used for a period of 2000-2016 to study the nature of climate change in the region. The findings of the study show that the climate variability and climate change for Mysore district, the monthly Rainfall is increased and monsoon Rainfall shows a decrease in trend. And the monthly, summer, monsoon minimum Temperature shows that decrease. Generally, the monthly maximum Temperature has decreased, but in case of summer and monsoon seasons increased respectively, and the monthly Relative Humidity has increased (positive). There is a decrease in Relative Humidity from January to April, and increase in the Relative Humidity during Monsoon season for Mysore District. The Annual average of Relative Humidity shows that it is increased for Mysore District. 展开更多
关键词 Climate Change RAINFALL Temperature Mysore DISTRICT
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Dust Source, Vertical Profile and Climate Impact by RegCM3 Regional Climate Model over West Africa during 2006 认领
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作者 Dialo Diop Demba Ndao Niang +1 位作者 Mamadou Simina Drame Abdoulaye Ba 《大气和气候科学(英文)》 2020年第2期206-219,共14页
This study aims to evaluate dust impact on climate parameters over the Sahel region by RegCM3 regional model during 2006. Indeed, aerosols are one of the main uncertainties in climate models. The aerosol optical depth... This study aims to evaluate dust impact on climate parameters over the Sahel region by RegCM3 regional model during 2006. Indeed, aerosols are one of the main uncertainties in climate models. The aerosol optical depth (AOD) derived from RegCM3 model has been validated with various observed datasets. The aerosol sources are identified over North Algeria and East of Sahel (Bodele depression). Discrepancies are noted when considering dust temporal and spatial distribution. Dust season extends between March and October, with two peaks of AOD recorded in March (spring) and June (summer). The dust vertical distribution showed that the mineral aerosol layer is located between 850 hPa and 300 hPa (1.5 km to 7 km). The RegCM3 model simulates fairly well the transport in the upper layers, especially in the Saharan Air Layer (SAL) during the summer. However, RegCM3 simulates poorly the transport and sedimentation of particles in the lower layers (below 2 km). The investigation of dust radiative impact shows a general cooling. The maximum of radiative forcing is located around 18&deg;N - 20&deg;N, with values of about -80 W/m2 in June - August (JJA) and -40 W/m2 at the surface during March - May (MAM). This study also showed the indirect effect of dust with a decrease in precipitation about -0.7 mm/day around 15 - 20&deg;N during the rainy season. 展开更多
关键词 Dust REGCM3 SAHEL Lidar AERONET Temperature RAINFALL WEST AFRICA
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Analysis of Precipitation and Temperature Variability over Central Africa (1901-2015) 认领
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作者 Yaw A. Twumasi Edmund C. Merem +7 位作者 John B. Namwamba Tomas Ayala-Silva Kamran Abdollahi Ronald Okwemba Onyumbe E. Ben Lukongo Caroline O. Akinrinwoye Joshua Tate Kellyn La Cour-Conant 《大气和气候科学(英文)》 2020年第2期220-239,共20页
Africa is already experiencing the impact of climate change. Some of the manifestations of climate change in Africa are, changing weather patterns resulting in, flooding and drought. Temperature change has impacted he... Africa is already experiencing the impact of climate change. Some of the manifestations of climate change in Africa are, changing weather patterns resulting in, flooding and drought. Temperature change has impacted health, livelihoods, productivity of food, availability of water, and state of security. This study examines the long-term climate variations in Central African Countries (Gabon, Cameroon, Republic of Congo, Central Africa Republic, Chad and Democratic Republic of Congo) for the period 1901 to 2015, and then investigates the possible influence of increases in greenhouse gas concentrations. To investigate climate patterns and trends in the Central African Countries, precipitation and temperature were analyzed on annual time scales using data collected from the World Bank Group Climate Change Knowledge Portal. Data was further aggregated using annual average blocks of 10 years. Linear and polynomial regression was performed. Also, linear time series slopes were analyzed to investigate the spatial and temporal trends of climate variability in Central African countries. Results of the analyses indicated that the mean annual temperature and precipitation records in some of the Central African Countries had both warming and cooling trends over the study period from 1901 to 2015. For example, differences between the maximum and the minimum rainfall data for Democratic Republic of Congo, Cameroon and Gabon were 13 mm, 13 mm and 11.1 mm, which corresponded to 11.04%, 10.03% and 10.44% respectively. The study also found the temperature of Chad to have significantly risen from 1901 to 2015 by almost 20%, while its rainfall’s variation was limited. Although the variation in rainfall in Chad was not dramatic, the temperature per 10 year rose by almost 20%. Chad’s temperature rose according to a cubic model from about 24.5°C to just below 27°C during the period 1901-1940. This was followed by a brief drop between 1940 and 1960. From 1960 to 2015 it rose according to the model to almost 28°C. By 2040 the tempe 展开更多
关键词 Temperature RAINFALL Climate VARIABILITY Linear and POLYNOMIAL Regression Central AFRICAN COUNTRIES
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温度影响下变截面梁自由振动与屈曲的微分变换法求解 认领
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作者 林鹏程 王俊淋 滕兆春 《甘肃科学学报》 2020年第3期6-9,16共5页
基于Euler-Bernoulli梁理论推导了变截面梁在温度影响下的自由振动控制微分方程,并利用微分变换法(DTM)对控制微分方程以及边界条件进行变换,求解了两端夹紧、两端简支、一端夹紧一端简支3种不同边界条件下变截面梁自由振动的无量纲固... 基于Euler-Bernoulli梁理论推导了变截面梁在温度影响下的自由振动控制微分方程,并利用微分变换法(DTM)对控制微分方程以及边界条件进行变换,求解了两端夹紧、两端简支、一端夹紧一端简支3种不同边界条件下变截面梁自由振动的无量纲固有频率和热屈曲临界温度。考虑了无量纲升温和截面变化系数对变截面梁自由振动频率的影响,并计算了不同截面变化系数情况下变截面梁达到屈曲状态时的无量纲临界温度。将计算结果与已有文献进行对比,说明了DTM的准确性和有效性。 展开更多
关键词 温度 变截面梁 自由振动 无量纲固有频率 热屈曲临界温度 微分变换法
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大跨径连续梁桥中的温度应力研究 认领
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作者 蔡洁 周清忘 陈伟 《江苏科技信息》 2020年第1期51-53,共3页
由于构件混凝土材料的属性,连续梁桥在温度载荷下会在内部引起较大的应力和应变,从而会产生裂缝。裂缝一旦形成,将对桥梁的交通安全和桥梁的使用产生重大影响。因此,文章认为研究温度荷载对于连续梁桥的影响是必要的,且具有一定的参考... 由于构件混凝土材料的属性,连续梁桥在温度载荷下会在内部引起较大的应力和应变,从而会产生裂缝。裂缝一旦形成,将对桥梁的交通安全和桥梁的使用产生重大影响。因此,文章认为研究温度荷载对于连续梁桥的影响是必要的,且具有一定的参考价值。 展开更多
关键词 温度 大跨度桥梁 温度荷载
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Analysis on Temporal Pattern of Fine Particulate Matter (PM<sub>2.5</sub>) in Hanoi, Vietnam and the Impact of Meteorological Conditions 认领
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作者 Chinh C. Tran Thi D. Ta +2 位作者 An T. Duong Oanh T. K. Phan Dung A. Nguyen 《环境保护(英文)》 2020年第3期246-256,共16页
Air quality is one of key issues to be addressed in the Vietnam environmental security strategy. As part of the strategy, this study investigates the temporal patterns of PM2.5 variations in Hanoi using data measured ... Air quality is one of key issues to be addressed in the Vietnam environmental security strategy. As part of the strategy, this study investigates the temporal patterns of PM2.5 variations in Hanoi using data measured from January 2017 to December 2018. The loglinear regression is used to analyze how the meteorological factors affect the PM2.5 variations. The analysis indicates the seasonal, monthly and diurnal variations of PM2.5 concentrations. The lowest concentration level is found in the summer due to hot climatic conditions with strong winds and high solar radiation. The highest PM2.5 concentration is observed in winter as a result of stagnation. The concentration levels from 2:00 AM to 8:00 AM tend to be higher than other hours of the day while the downtrend is recorded from 11:00 AM to 7:00 PM and reaches the lowest levels of the day at 2:00 PM to 3:00 PM. The study results provide important information for government authorities, international and civil society organizations on when and why the PM2.5 concentration levels increase. This predictive analysis would be useful to develop early warning systems and to minimize the negative impacts of air pollution on public health. 展开更多
关键词 PM2.5 VARIATIONS WIND Speed Temperature Solar Radiation and Air Pressure
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