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Effect of Planting Methods on the Yield and Yield Attributes of Short Duration <i>Aman</i>Rice 被引量:3
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作者 Md. Masud Rana Md. Abdullah Al Mamun +2 位作者 Afruz Zahan Md. Nayeem Ahmed Md. Abdul Jalil Mridha 《American Journal of Plant Sciences》 2014年第3期251-255,共5页
To find out the effect of planting methods on the yield and yield attributes of short duration Aman rice varieties, a field trial was conducted at the farm of Bangladesh Rice Research Institute, Gazipur, during July t... To find out the effect of planting methods on the yield and yield attributes of short duration Aman rice varieties, a field trial was conducted at the farm of Bangladesh Rice Research Institute, Gazipur, during July to November 2012. The treatments comprised of three BRRI released high yielding varieties viz., BRRI dhan39, BRRI dhan49 and BRRI dhan57 and three planting methods viz., direct seeding of dry seed, direct seeding of sprouted seed and transplanting. It was a factorial experiment conducted in a Randomized Complete Block Design with three replications. Planting methods had a significant effect on the growth duration of rice. The rice crop established with direct seeding of the dry and sprouted seed matured 7 days earlier than transplanting. The variety BRRI dhan39 gave the highest yield (4.964 t·ha-1) when grown with direct seeding of sprouted seed compared to other varieties. The highest net return (23362.00 BDT ha-1) and cost benefit ratio (1:1.49) were observed in direct seeding of the sprouted seed method. So, direct seeding of sprouted seed might be the best planting method because about 19.94% production cost is reduced due to the omission of seedling raising and transplanting operations as well as the reduction in the length of the crop cultivation period. 展开更多
关键词 Direct SEEDING of Dry and Sprouted SEED Growth duration short duration Aman RICE
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Effect of microstructure on short pulse duration shock initiation of TATB and initial response mechanism 被引量:2
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作者 Jun Wang Wei Cao +4 位作者 Xiang-li Guo Bi-bo Cheng Lu-lu Zhao Rui-rui Liu Xiao-wei Chen 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2020年第2期374-380,共7页
Micro-TATB particles with different sizes and 3D nanoporous TATB architectures with different specific surface areas were prepared through recrystallization to study short pulse duration shock initiation properties by... Micro-TATB particles with different sizes and 3D nanoporous TATB architectures with different specific surface areas were prepared through recrystallization to study short pulse duration shock initiation properties by electric gun technology.For micro-TATB,the initiation threshold significantly decreases with TATB average size ranging from 79.7μm to 0.5μm.For 3D nanoporous TATB architecture,the initiation threshold decreases and then increases with specific surface areas increased from 9.6 m^2/g to36.2 m^2/g.The lowest initiation thresholds are obtained for the micro-TATB with average sizes of 1.3μm and 0.5μm,and 3D nanoporous TATB architecture with specific surface area of 22.4 m^2/g.The shock initiation thresholds of micro-TATB and 3D nanoporous TATB architectures show significantly decreases with the porosity increased.The decomposition reaction and thermal conductivity properties were further investigated to understand the initial response mechanism.High porosity provides more collapse sites to generate high temperature for formation of hot spots.The low thermal conductivity and decomposition temperature could enhance the formation and ignition of the hot spots,and initial decomposition reaction of TATB.The effect of the decomposition temperature is higher than that of the thermal conductivity on the shock initiation properties.The enhanced decomposition reaction could pro mote energy release and transfer process from the ignition to the combustio n.This work offe rs a new insight to understand the effects of microstructure on the shock initiation properties and the initial response mechanism of TATB. 展开更多
关键词 short pulse duration shock INITIATION MICROSTRUCTURE TATB architecture Chemical reaction INITIAL response mechanism
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CORRELATION BETWEEN PEAK INTENSITY OF EXTREME AFTERNOON SHORT-DURATION RAINFALL AND HUMIDITY AND SURFACE AIR TEMPERATURE IN SOUTHEAST COAST OF CHINA 被引量:1
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作者 孙溦 原韦华 +1 位作者 李建 宇如聪 《Journal of Tropical Meteorology》 SCIE 2015年第3期276-284,共9页
Using hourly rainfall intensity, daily surface air temperature, humidity and low-level dew point depressions at55 stations in the southeast coast of China, and sea surface temperature from reanalysis in the coastal re... Using hourly rainfall intensity, daily surface air temperature, humidity and low-level dew point depressions at55 stations in the southeast coast of China, and sea surface temperature from reanalysis in the coastal region, this paper analyzes the connection between peak intensity of extreme afternoon short-duration rainfall(EASR) and humidity as well as surface air temperature. The dependency of extreme peak intensity of EASR on temperature has a significant transition. When daily highest surface temperature is below(above) 29°C, the peak rainfall intensity shows an ascending(descending) tendency with rising temperature. Having investigated the role of moisture condition in the variation of EASR and temperature, this paper discovered that the decrease of peak rainfall intensity with temperature rising is connected with the variation of relative humidity. At higher temperatures, the land surface relative humidity decreases dramatically as temperature further increases. During this process, the sea surface temperature maintains basically unchanged, resulting in indistinct variations of water vapor content at seas. As water vapor over land is mainly contributed by the quantitative moisture transport from adjacent seas, the decline of relative humidity over land will be consequently caused by the further rise of surface air temperature. 展开更多
关键词 extreme rainfall short duration surface air temperature relative humidity
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Short-duration transient visual evoked potentials and color reflectivity discretization analysis in glaucoma patients and suspects 被引量:1
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作者 Michael Waisbourd Rebekah H.Gensure +7 位作者 Ardalan Aminlari Sonya B.Shah Nitasha Khanna Neil Sood Jeanne Molineaux Alberto Gonzalez Jonathan S.Myers L.Jay Katz 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2017年第2期254-261,共8页
AIM: To evaluate the use of short-duration transient visual evoked potentials(VEP) and color reflectivity discretization analysis(CORDA) in glaucomatous eyes,eyes suspected of having glaucoma,and healthy eyes.MET... AIM: To evaluate the use of short-duration transient visual evoked potentials(VEP) and color reflectivity discretization analysis(CORDA) in glaucomatous eyes,eyes suspected of having glaucoma,and healthy eyes.METHODS: The study included 136 eyes from 136 subjects: 49 eyes with glaucoma,45 glaucoma suspect eyes,and 42 healthy eyes.Subjects underwent Humphrey visual field(VF) testing,VEP testing,as well as peripapillary retinal nerve fiber layer optical coherence tomography imaging studies with post-acquisition CORDA applied.Statistical analysis was performed using means and ranges,ANOVA,post-hoc comparisons using Turkey's adjustment,Fisher's Exact test,area under the curve,and Spearman correlation coefficients.RESULTS: Parameters from VEP and CORDA correlated significantly with VF mean deviation(MD)(P〈0.05).In distinguishing glaucomatous eyes from controls,VEP demonstrated area under the curve(AUC) values of 0.64-0.75 for amplitude and 0.67-0.81 for latency.The CORDA HR1 parameter was highly discriminative for glaucomatous eyes vs controls(AUC=0.94).CONCLUSION: Significant correlations are found between MD and parameters of short-duration transient VEP and CORDA,diagnostic modalities which warrant further consideration in identifying glaucoma characteristics. 展开更多
关键词 short-duration transient visual evoked potentials optical coherence tomography color reflectivity discretization analysis GLAUCOMA
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Spatial Pattern Difference of Contribution between Short and Long-duration Heavy Rainfall to Total Heavy Rainfall in China from 1961 to 2015
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作者 Kong Feng 《Meteorological and Environmental Research》 CAS 2019年第4期51-60,共10页
Many regions are pounded with heavy rainfall, causing flood, casualties, property damage and severe destruction to ecosystem in multiple urban areas. Frequent occurrence of extremely heavy precipitation event under th... Many regions are pounded with heavy rainfall, causing flood, casualties, property damage and severe destruction to ecosystem in multiple urban areas. Frequent occurrence of extremely heavy precipitation event under the background of global climate change has caused terrible harm on economic and social development, life security, ecosystem, etc.;brought profound impact on sustainable development of disaster area;become a key factor of global and regional disasters and environmental risk;and been widely concerned by academic circle and all sectors of the society. So severe disasters caused by extreme precipitation events have attracted more and more attention, while the relationship between heavy rainfall with different duration and total heavy rainfall has become the hottest scientific frontier issue. Contribution of heavy rainfall with different duration to the total heavy rainfall has significant spatial differences. Here we used daily rainfall data from 1961 to 2015 of 659 meteorological stations in China. When the rainfall is greater than 50 mm in 24 hours, that is a heavy rainfall event. Heavy rainfall only lasting one day is defined as short- duration heavy rainfall, while heavy rainfall lasting more than two days is defined as long-duration heavy rainfall. Results indicated that: on the basis of duration days defined long-duration heavy rainfall, on the spatial distribution, total rainfall, total heavy rainfall and short-duration heavy rainfall showed "increasing-decreasing-increasing" from the southeast coast to northwest inland in China from 1961 to 2015, and on the whole meteorological station with increasing trend predominant. In the meantime, long-duration heavy rainfall showed "increasing-decreasing" spatial pattern, and on the whole meteorological station with decreasing trend predominant. We detected that there was a belt of becoming drought from northeast to southwest. The contribution of total heavy rainfall to total rainfall as well as long-duration heavy rainfall to total heavy rainfall showed "high in southeast-low in northwest" spatial distribution pattern. On the contrary, the contribution of short-duration heavy rainfall to total heavy rainfall showed "low in southeast-high in northwest" spatial distribution pattern. The contribution trend of total heavy rainfall to total rainfall and short-duration heavy rainfall to total heavy rainfall showed "increasing-mosaic with increasing and decreasing-increasing" spatial distribution pattern from northeast to southwest, and on the whole meteorological station with increasing trend predominant. On the contrary, the contribution trend of long-duration heavy rainfall to total heavy rainfall showed mosaic with increasing and increasing in the northeast, slightly decreasing in the southwest, and on the whole meteorological station with decreasing trend predominant. There was a climate transition zone from northeast to southwest, which was essentially coincident with the arid zone. The results suggested that the precipitation in China was changing to extremely accompanied by short-duration storm increased significantly. Chinese heavy rainfall especially the increase of short-duration heavy rainfall suggests that human activity is likely to be triggered an increasing in extreme precipitation. 展开更多
关键词 Precipitation CONTRIBUTION Spatial DIFFERENCE Long and short-duration HEAVY RAINFALL Total HEAVY RAINFALL China
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Effect of ground motion duration on inelastic displacement ratio of SDOF systems 被引量:1
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作者 Saman Yaghmaei-Sabegh Sonia Daneshgari 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2023年第2期423-439,共17页
In this paper,the influence of ground motion duration on the inelastic displacement ratio,C_(1),of highly damped SDOF systems is studied.For this purpose,two sets of spectrally equivalent long and short duration groun... In this paper,the influence of ground motion duration on the inelastic displacement ratio,C_(1),of highly damped SDOF systems is studied.For this purpose,two sets of spectrally equivalent long and short duration ground motion records were used in an analysis to isolate the effects of ground motion duration on.The effect of duration was evaluated for observed values of C_(1) by considering six ductility levels,and different damping and post-yield stiffness ratios.A new predictive equation of C_(1) also was developed for long and short duration records.Results of non-linear regression analysis of the current study provide an expression with which to quantify the duration effect.Based on the average values of estimated C_(1) ratios for long duration records divided by C_(1) for a short duration set,it is concluded that the maximum difference between long and short duration records occurs when the damping ratio is 0.3 and the post-yield stiffness ratio is equal to zero. 展开更多
关键词 inelastic displacement ratio long and short duration earthquakes highly damped SDOF systems DUCTILITY
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Beat-to-Beat Variability in Field Potential Duration in Human Embryonic Stem Cell-Derived Cardiomyocyte Clusters for Assessment of Arrhythmogenic Risk, and a Case Study of Its Application 被引量:1
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作者 Kazuto Yamazaki Taro Hihara +7 位作者 Hiroshi Kato Tatsuto Fukushima Kazuyuki Fukushima Tomohiko Taniguchi Takashi Yoshinaga Norimasa Miyamoto Masashi Ito Kohei Sawada 《Pharmacology & Pharmacy》 2014年第1期117-128,共12页
We established a QT interval assessment system that uses human embryonic stem cell-derived cardiomyocyte clusters (hES-CMCs) in which the field potential duration (FPD) or corrected FPD (FPDc) was measured as an indic... We established a QT interval assessment system that uses human embryonic stem cell-derived cardiomyocyte clusters (hES-CMCs) in which the field potential duration (FPD) or corrected FPD (FPDc) was measured as an indicator of drug-induced QT interval prolongation. To investigate the applicability of the hES-CMC system to drug safety assessment, we investigated short-term variability in FPDc (STVFPDc) (beat rate rhythmicity) as a marker of torsadogenic risk. We investigated the FPDc and STVFPDc of hES-CMCs treated with hERG channel blockers (E-4031 or cisapride) or with our proprietary compounds X, Y, and Z. We also evaluated the electrocardiograms and hemodynamics of dogs treated with compound X, Y, or Z. The torsadogenic hERG channel blockers increased STVFPDc and prolonged FPDc. Compounds X, Y, and Z had hERG inhibitory activity. Compound X prolonged FPDc with increased STVFPDc, whereas compounds Y and Z tended to shorten FPDc in the hES-CMC system. In the in vivo canine study, compound X prolonged corrected QT (QTc), and compounds Y and Z tended to shorten QTc, showing a good correlation with the results in hES-CMCs. These findings suggest that combined assessment of FPDc and STVFPDc in the hES-CMC system increases the predictability of torsadogenic risk. 展开更多
关键词 Human Embryonic Stem Cell-Derived Cardiomyocytes Field Potential duration short-Term VARIABILITY QT Interval Torsades de POINTES RISK ASSESSMENT
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Raman Scattering at Resonant or Near-Resonant Conditions: A Generalized Short-Time Approximation
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作者 Abdelsalam Mohammed 孙玉萍 +2 位作者 苗泉 Hans Agren Faris Gel'mukhanov 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2012年第1期31-47,I0003,共18页
We investigate the dynamics of resonant Raman scattering in the course of the frequency de- tuning. The dephasing in the time domain makes the scattering fast when the photon energy is tuned from the absorption resona... We investigate the dynamics of resonant Raman scattering in the course of the frequency de- tuning. The dephasing in the time domain makes the scattering fast when the photon energy is tuned from the absorption resonance. This makes frequency detuning to act as a camera shutter with a regulated scattering duration and provides a practical tool of controlling the scattering time in ordinary stationary measurements. The theory is applied to resonant Raman spectra of a couple of few-mode model systems and to trans-1,3,5-hexatriene and guanine-cytosine (G-C) Watson-Crick base pairs (DNA) molecules. Besides some particular physical effects, the regime of fast scattering leads to a simplification of the spectrum as well as to the scattering theory itself. Strong overtones appear in the Raman spectra when the photon frequency is tuned in the resonant region, while in the mode of fast scattering, the overtones are gradually quenched when the photon frequency is tuned more than one vibra- tional quantum below the first absorption resonance. The detuning from the resonant region thus leads to a strong purification of the Raman spectrum from the contamination by higher overtones and soft modes and purifies the spectrum also in terms of avoidance of dissociation and interfering fluorescence decay of the resonant state. This makes frequency detuning a very useful practical tool in the analysis of the resonant Raman spectra of complex systems and considerably improves the prospects for using the Raman effect for detection of foreign substances at ultra-low concentrations. 展开更多
关键词 Resonant Raman Scattering duration Hexatriene short time approximation
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Efficiency of Severe Recorded Rainstorms over Maharashtra State
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作者 B.D.Kulkarni Miss Shobha Nandargi O. N. Dhar 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 1995年第1期103-108,共6页
12 severe rainstorms have been experienced by different meteorological sub-divisions of Maharashtra State during the last 100-year period from 1891-1990. For each of the rainstorms efficiency factors (i.e. P/ M ratios... 12 severe rainstorms have been experienced by different meteorological sub-divisions of Maharashtra State during the last 100-year period from 1891-1990. For each of the rainstorms efficiency factors (i.e. P/ M ratios) were worked out for maximum one-day duration and for three standard areas of 1000, 5000, and 10,000 km2. Comparison of these ratios with the past has shown that the most efficient rainstorm over Maharashtra was the rainstorm of June, 1908 over the Vidarbha region whose full DAD data as well as isohyetal pattern have been given. 展开更多
关键词 Rainstonn Depth-area -duration (DAD) Efficiency factor of rainstorms Probable Maximum Precipitation (PMP)
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Study on Design Rainstorm Profile in Liuzhou City Based on Pilgrim &Cordery Method
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作者 Xiaoling Su Dong Xie +5 位作者 Lei Liu Chunrong Liang Zhourong Liu Yu Li Qiu Lan Le Ren 《Journal of Geoscience and Environment Protection》 2019年第3期136-144,共9页
Liuzhou City is located in Guangxi Zhuang Autonomous Region of China. It has a warm and rainy climate and belongs to the middle subtropical monsoon climate. It is a rainstorm and flood-prone area. The work of flood dr... Liuzhou City is located in Guangxi Zhuang Autonomous Region of China. It has a warm and rainy climate and belongs to the middle subtropical monsoon climate. It is a rainstorm and flood-prone area. The work of flood drainage and waterlogging prevention is very important. The “minute to minute” rainfall process data of Liuzhou National Meteorological Observation Station from 1975 to 2014 and the Pilgrim & Cordery method were used to estimate the short-time design rainstorm profile of Liuzhou City, and the profiles of the rainfall lasting for 30, 60, 90, 120, 150, and 180 min were obtained. The research shows that the same rain duration and different recurrence period conditions are consistent with the rainstorm profile. The rainfall duration of 30, 60, 90, 120, and 180 min generally shows single-peak rainstorm profile, and the rainfall duration of 150 min shows double-peak rainstorm profile. Most peaks of each short-time design rainstorm profile are at or ahead of the 1/3 part of the entire rainfall process. During the same recurrence period, the rainfall in peak period fluctuated with the increase of the duration, and the intensity of rainfall increased with the prolonging of the recurrence period. 展开更多
关键词 Liuzhou CITY PILGRIM & Cordery METHOD short-Time rainstorm DESIGN rainstorm PROFILE
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四川两次极端暴雨强降水特征及与雷达回波和闪电关系分析
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作者 周威 魏庆 +3 位作者 杨康权 康岚 罗辉 黄楚惠 《高原山地气象研究》 2024年第1期104-110,共7页
选取了2020年8月四川两次历史性极端暴雨过程,根据量级和持续时间对强降水进行划分,分析其时空分布特征及与雷达回波和闪电的关系。结果表明:短时强降水主要发生在22时—次日03时,降水强度为30~<50 mm/h的站次最多,区域集中在盆地西... 选取了2020年8月四川两次历史性极端暴雨过程,根据量级和持续时间对强降水进行划分,分析其时空分布特征及与雷达回波和闪电的关系。结果表明:短时强降水主要发生在22时—次日03时,降水强度为30~<50 mm/h的站次最多,区域集中在盆地西部。随着降水量级的增加,站点对应的闪电密度均增大,小时平均回波、最强回波、最弱回波均呈增强的趋势。随着降水持续时间的增加,站点对应的负地闪平均强度增强。第一次过程强降水站次与闪电频次的高值中心具有良好的对应关系。第二次过程随着降水量级增大,对应的回波均方根误差减小,而第一次过程则相反。 展开更多
关键词 极端暴雨 短时强降水 时空特征 雷达回波 闪电
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定点形变数据中暂态短持时异常信号的检测方法研究
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作者 张源 崔庆谷 《大地测量与地球动力学》 CSCD 北大核心 2024年第1期100-104,共5页
分别将线性叠加及零延迟相乘算法用于人工合成数据中的暂态信号检测实验,对比2种算法在暂态信号识别中的效果。结果表明,将同台多道、多台多道数据进行零延时相乘能够更有效地压制数据中的干扰和噪声,使准同步暂态信号得到放大凸显,实... 分别将线性叠加及零延迟相乘算法用于人工合成数据中的暂态信号检测实验,对比2种算法在暂态信号识别中的效果。结果表明,将同台多道、多台多道数据进行零延时相乘能够更有效地压制数据中的干扰和噪声,使准同步暂态信号得到放大凸显,实现暂态异常信号的初步检测与识别。在此基础上,利用零延时相乘算法处理2002~2022年云南定点形变观测数据,从中识别出11组暂态短持时信号,并进一步分析信号与云南境内M_(S)5.0以上地震的时空关联性。 展开更多
关键词 暂态短持时信号 同类同分向数据 零延迟相乘 信号检测与识别
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川西高原和攀西地区不同级别短时强降水环境参量特征对比分析
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作者 张武龙 杨康权 +1 位作者 康岚 银航 《高原山地气象研究》 2024年第2期75-82,共8页
利用2010—2021年5—9月川西高原和攀西地区62个国家级自动站逐小时观测资料及时间分辨率为1 h的ERA5再分析资料,对比分析了两区域不同级别短时强降水发生发展过程中水汽、热力和垂直风切变等环境参量特征。结果表明:川西高原和攀西地... 利用2010—2021年5—9月川西高原和攀西地区62个国家级自动站逐小时观测资料及时间分辨率为1 h的ERA5再分析资料,对比分析了两区域不同级别短时强降水发生发展过程中水汽、热力和垂直风切变等环境参量特征。结果表明:川西高原和攀西地区短时强降水主要集中在6—8月,午后至前半夜是川西高原短时强降水的高发时段,攀西地区则表现出明显的夜雨特征。就川西高原而言,较好的水汽、热力条件和较强的垂直风切变、上升运动均有利于高级别短时强降水的产生;不同级别短时强降水的CAPE值差异显著,1100 J·kg^(−1)可作为判断是否出现20 mm·h^(−1)以上短时强降水的参考阈值。就攀西地区而言,不同级别短时强降水在暖云层厚度、700 hPa比湿、700 hPa假相当位温、CAPE、0~3 km垂直风切变等环境参量的值域分布上均存在明显差异;当700 hPa比湿大于13 g·kg^(−1)、CPAE值超过1100 J·kg^(−1)、0~3 km垂直风切变达到10 m·s^(−1)时,极易出现50 mm·h^(−1)以上的短时强降水。 展开更多
关键词 川西高原 攀西地区 短时强降水 环境参量 ERA5再分析资料
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吕梁山两次夜间暴雨的边界层特征及能量来源与转换
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作者 王一颉 赵桂香 《沙漠与绿洲气象》 2024年第2期35-43,共9页
利用常规观测、NCEP/NCAR 1°×1°再分析、FY-2E卫星数据等资料,对分别由β-中尺度持续拉长状对流系统(MβECS)和中尺度对流复合体(MCC)造成的两次吕梁山夜间暴雨过程进行数值模拟和粒子后向轨迹追踪,结果表明:过程1受边... 利用常规观测、NCEP/NCAR 1°×1°再分析、FY-2E卫星数据等资料,对分别由β-中尺度持续拉长状对流系统(MβECS)和中尺度对流复合体(MCC)造成的两次吕梁山夜间暴雨过程进行数值模拟和粒子后向轨迹追踪,结果表明:过程1受边界层南风急流和西南气流影响,山西西部低空急流偏西分量和晋中盆地边界层西南气流的增强是对流不稳定能量重建的重要因子。过程2则受边界层南风和东风急流作用,南风急流被显著抬升到对流层中高层,形成含有冰晶层的中高层云系,东风急流则供应低空水汽。两次过程边界层(0.8-1.2 km)粒子携带的水汽均明显超过低层(1.5-3 km),是夜间短时强降水所需水汽的最大贡献者。700 hPa及以上非绝热作用产生扰动有效位能,之后向扰动动能的转化是两次过程中短时强降水发生所需能量的主要来源。 展开更多
关键词 夜间暴雨 中尺度对流系统 边界层 短时强降水 能量转换
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基于暴雨灾害短视频的多模态情感特征研究
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作者 晋良海 王抒情 王昕煜 《中国安全科学学报》 CAS CSCD 北大核心 2024年第7期219-228,共10页
为提高灾害应对效率,将“河北暴雨”“黑龙江暴雨”作为典型跨区域研究案例,收集短视频的文本-图像-音频多模态数据;面对海量的非结构化数据,运用深度学习技术,构建多模态情感智能分类模型,实现短视频情感特征的提取、跨模态融合与智能... 为提高灾害应对效率,将“河北暴雨”“黑龙江暴雨”作为典型跨区域研究案例,收集短视频的文本-图像-音频多模态数据;面对海量的非结构化数据,运用深度学习技术,构建多模态情感智能分类模型,实现短视频情感特征的提取、跨模态融合与智能情感分类;并综合利用时空大数据,在时空维度上深度挖掘与分析暴雨灾害短视频多模态情感特征。结果表明:该模型准确率达85%以上,能有效实现短视频多模态情感智能分类任务。在时间维度上,网民情感波动与暴雨灾害周期大致相符,可作为判断灾情严重程度和舆情走向的依据;媒体及政府的干预对暴雨灾害情感演化具有重要作用。在空间维度上,消极情感随灾情转移呈现“低—高—低”变化趋势,且消极情感的共鸣和扩散效应呈现明显的地域性特征,需重视灾区、我国部分东部地区及类似灾害频发的非灾区舆情引导工作。 展开更多
关键词 暴雨灾害 短视频 多模态情感特征 深度学习 情感分类
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短时程替罗非班在高血栓负荷的老年急性心肌梗死患者围术期应用的安全性及疗效观察 被引量:1
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作者 安乐 康晰 +6 位作者 王力 张慧 任延昭 田雪 田芳 张玲 隋春兴 《中华老年心脑血管病杂志》 CAS 北大核心 2024年第8期871-875,共5页
目的观察围术期短时程血小板膜糖蛋白Ⅱb/Ⅲa受体拮抗剂(platelet membrane glycoproteinⅡb/Ⅲa receptor antagonist,GPI)治疗策略在高血栓负荷老年急性ST段抬高型心肌梗死(ST-segment elevation myocardial infarction,STEMI)患者行... 目的观察围术期短时程血小板膜糖蛋白Ⅱb/Ⅲa受体拮抗剂(platelet membrane glycoproteinⅡb/Ⅲa receptor antagonist,GPI)治疗策略在高血栓负荷老年急性ST段抬高型心肌梗死(ST-segment elevation myocardial infarction,STEMI)患者行直接经皮冠状动脉介入治疗中的安全性及有效性。方法回顾性分析2021年10月至2024年1月大连理工大学附属大连市中心医院收治的老年急性STEMI患者140例,根据随机数字法分为实验组(短时程)和对照组(标准时程),每组70例。观察2组术后主要不良心脏事件发生情况、术后2 h的ST段完全回落率、急性心肌梗死溶栓试验(thrombolysis in myocardial infarction,TIMI)血流分级、左心室射血分数、N末端B型钠尿肽前体(N-terminal pro-B-type natriuretic peptide,NT-proBNP)、血栓弹力图测定血小板聚集抑制率及二磷酸腺苷(adenosine diphosphate,ADP)受体途径的最大振幅(maximum amplitude,MA_(ADP))、血小板相关指标、血小板减少症及出血事件。结果2组术后复发心绞痛、急性心力衰竭、恶性心律失常、ST段回落率、TIMI血流恢复3级、无复流、左心室射血分数、出院前NT-proBNP、住院期间严重大出血及血小板减少症比较,差异无统计学意义(P>0.05)。实验组术后18 h的血小板聚集抑制率明显低于对照组[(76.1±15.3)%vs(96.3±19.4)%,P=0.016],MA_(ADP)明显高于对照组[(45.6±8.2)mm vs(26.7±9.7)mm,P=0.028]。实验组住院期间轻微出血发生率明显少于对照组(7.1%vs 24.3%,P<0.05)。结论短时程GPI在应用新型口服嘌呤能受体P2Y12抑制剂的前提下,血小板抑制率达标情况并不劣于标准时程;有同样的有效性及相对更好的安全性。 展开更多
关键词 心肌梗死 替罗非班 经皮冠状动脉介入治疗 短时程
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华北平原及沿山和沿海五个城市夏季短历时降水过程的日变化分析 被引量:1
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作者 丁乙 窦晶晶 +2 位作者 王迎春 苗世光 樊利强 《气象学报》 CAS CSCD 北大核心 2024年第4期490-509,共20页
利用华北平原294个国家级气象站1980—2022年夏季(6—8月)逐时降水资料,分析了华北平原夏季短历时降水过程的日变化时、空分布特征,结合地面气温和风的日变化,综合分析了4个沿山城市(北京、石家庄、济南、郑州)和1个沿海城市(天津)在城... 利用华北平原294个国家级气象站1980—2022年夏季(6—8月)逐时降水资料,分析了华北平原夏季短历时降水过程的日变化时、空分布特征,结合地面气温和风的日变化,综合分析了4个沿山城市(北京、石家庄、济南、郑州)和1个沿海城市(天津)在城市发展前期(1980—1989年)和后期(2013—2022年)短历时降水过程日变化特征及差异。结果表明:华北平原短历时降水过程整体呈现傍晚单峰的日变化特征;平原站点的达峰时间自东南向西北推后。5个主要城市在城市发展后期,短历时降水过程的日振幅都出现不同程度的减小;沿山城市短历时降水过程日峰值出现时间提前了1—2 h,而沿海城市天津无明显峰值时间,且高值时段提前;沿山城市50 mm以上短历时降水过程概率均有所升高,其中北京和石家庄40 mm以上的降水过程概率分别升高了2倍和5倍,而沿海城市天津40 mm以上的降水过程概率下降了43%。华北平原短历时降水过程的日变化与局地地形的热、动力作用和地面盛行风有关。城市局地增温效应导致沿山、沿海城市与周围地形热力差异更加明显,增强了沿山城市的山风和沿海城市的海风;同时,城市增温导致城市午后地面风辐合增强。近地面层上述热力差异变化导致的风场变化可能是沿山城市短历时降水过程日峰值提前、沿海城市短历时降水过程集中时段变为白天的重要原因。 展开更多
关键词 短历时降水过程 日变化 城市效应 地形 华北平原
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基于图注意力网络的城市内涝积水预测与研究
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作者 胡昊 孙爽 +2 位作者 马鑫 李擎 徐鹏 《人民黄河》 CAS 北大核心 2024年第4期43-48,共6页
极端暴雨天气多发频发造成的城市内涝,严重威胁居民的人身财产安全,准确高效的内涝点积水面积预测在提高城市灾害应急处置能力中发挥着至关重要的作用。为了提高城市内涝点积水预测的准确性和直观性,提出一种基于GAT和LSTM网络的GATLST... 极端暴雨天气多发频发造成的城市内涝,严重威胁居民的人身财产安全,准确高效的内涝点积水面积预测在提高城市灾害应急处置能力中发挥着至关重要的作用。为了提高城市内涝点积水预测的准确性和直观性,提出一种基于GAT和LSTM网络的GATLSTM组合预测模型,通过GAT提取积水信息局部空间特征,并通过节点分配权重的方式加强对关键信息序列的记忆,随后采用LSTM提取积水面积序列的时间特征,对内涝点积水面积进行预测。以开封市区某内涝点的积水数据建立模型并评估验证,将GATLSTM模型和LSTM、GAT以及GCNLSTM模型进行对比,结果表明:GATLSTM模型的预测精度优于另外3种模型,能够准确地对内涝点积水面积进行预测,可以为防汛工作和应急响应措施的制定提供科学依据。 展开更多
关键词 积水预测 城市暴雨 图注意力网络 长短期记忆网络
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京津冀暖季短时强降水环境特征对比分析
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作者 申莉莉 李江波 +3 位作者 王秀明 钟琦 李文晴 孙卓 《气象与环境学报》 2024年第1期37-46,共10页
利用2013—2021年暖季(6—9月)京津冀地区逐时降水资料和ERA5再分析资料,根据天气形势对短时强降水进行天气学分型,统计短时强降水发生的时空特征,对比动力、水汽和热力不稳定条件等环境要素特征。结果表明:短时强降水以冷涡型和副高型... 利用2013—2021年暖季(6—9月)京津冀地区逐时降水资料和ERA5再分析资料,根据天气形势对短时强降水进行天气学分型,统计短时强降水发生的时空特征,对比动力、水汽和热力不稳定条件等环境要素特征。结果表明:短时强降水以冷涡型和副高型为主,占到55%,且主要发生在7月中下旬到8月上中旬,强降水主要集中在下午到前半夜。对比发现,不同类型短时强降水空间分布特征区别明显,分型合理;各类型大多表现为低层辐合和高层辐散,西南涡型动力强度表现最强,且随降水临近是增加的,弱天气强迫型在降水前各个时段动力表现最弱;副高型、台风型和西南涡型水汽最为充沛,副高型925 hPa比湿中位数达到19.14 g·kg~(-1),西南涡型在高低层相对湿度均较大,低层平均相对湿度中位数达到87%,弱天气强迫型相对较差,为74%,各类型整层大气可降水量在降水前随时间基本是增加的;弱天气强迫型的热力不稳定性最为突出,850 hPa和500 hPa温度差中位数最大为25.74℃,西南涡型最小,除弱天气强迫型外,各类型热力条件随时间是减弱的。 展开更多
关键词 短时强降水 分型 环境条件
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短历时强降雨对喀斯特玉米坡地产流产沙的影响
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作者 杨应冲 戴全厚 +2 位作者 王勇 张友 姚一文 《水土保持通报》 CSCD 北大核心 2024年第4期126-134,共9页
[目的]研究短历时强降雨对喀斯特坡耕地产流产沙的影响,揭示喀斯特坡耕地土壤侵蚀特征机理,为解决喀斯特坡耕地土壤侵蚀和保障粮食生产提供科学依据。[方法]通过人工模拟降雨试验,以喀斯特裸坡地和玉米坡地为研究对象,研究短历时强降雨... [目的]研究短历时强降雨对喀斯特坡耕地产流产沙的影响,揭示喀斯特坡耕地土壤侵蚀特征机理,为解决喀斯特坡耕地土壤侵蚀和保障粮食生产提供科学依据。[方法]通过人工模拟降雨试验,以喀斯特裸坡地和玉米坡地为研究对象,研究短历时强降雨对喀斯特坡耕地产流产沙的影响。[结果](1)裸坡地和玉米地地表产流产沙模数随坡度的增大而增大,当坡度相同时,玉米地地表产流产沙模数显著小于裸坡地(p<0.05);随着降雨历时的增加,裸坡地和玉米地地表产流模数呈现出先增大后保持稳定的趋势,而地表产沙模数则是先增大后减小。(2)裸坡地和玉米地各壤中流产流模数随坡度的增大而增大;当坡度相同时,玉米地各壤中流产流量显著小于裸坡地(p<0.05),其中坡度为20°时,玉米地壤中流(15—25 cm)总产流量相对裸坡地减少了62.59%。(3)当坡度不变时,玉米地地下产沙量和产沙模数显著小于裸坡地(p<0.05);随着降雨历时的增加,裸坡地与玉米地地下产流模数呈现出不断增大的趋势,其变化趋势基本保持一致,而地下产沙模数呈现先增大后减小的趋势,在20~30 min之间达到最大产沙模数。(4)比较不同坡度裸坡地与玉米地各产流产沙之间的相关性,发现玉米地相比裸坡地地下产沙与地表产流、地下产流、地表产沙之间相关性增强,而地表产沙与地表产流、地下产流之间的相关性减弱。[结论]强降雨下玉米坡地能够增加入渗,具有阻控和缓蚀的作用,其中地表产流产沙模数和壤中流产流模数随坡度的增大而增大,而地下产流模数随降雨历时增加呈不断增大的趋势,地下产沙模数呈先增大后减小的趋势。 展开更多
关键词 喀斯特坡耕地 短历时强降雨 产流模数 产沙模数
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