期刊文献+
共找到5,409篇文章
< 1 2 250 >
每页显示 20 50 100
Motor Fault Diagnosis Based on Short-time Fourier Transform and Convolutional Neural Network 被引量:41
1
作者 Li-Hua Wang Xiao-Ping Zhao +2 位作者 Jia-Xin Wu Yang-Yang Xie Yong-Hong Zhang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2017年第6期1357-1368,共12页
With the rapid development of mechanical equipment, the mechanical health monitoring field has entered the era of big data. However, the method of manual feature extraction has the disadvantages of low efficiency and ... With the rapid development of mechanical equipment, the mechanical health monitoring field has entered the era of big data. However, the method of manual feature extraction has the disadvantages of low efficiency and poor accuracy, when handling big data. In this study, the research object was the asynchronous motor in the drivetrain diagnostics simulator system. The vibration signals of different fault motors were collected. The raw signal was pretreated using short time Fourier transform (STFT) to obtain the corresponding time-frequency map. Then, the feature of the time-frequency map was adap- tively extracted by using a convolutional neural network (CNN). The effects of the pretreatment method, and the hyper parameters of network diagnostic accuracy, were investigated experimentally. The experimental results showed that the influence of the preprocessing method is small, and that the batch-size is the main factor affecting accuracy and training efficiency. By investigating feature visualization, it was shown that, in the case of big data, the extracted CNN features can represent complex mapping relationships between signal and health status, and can also overcome the prior knowledge and engineering experience requirement for feature extraction, which is used by tra- ditional diagnosis methods. This paper proposes a new method, based on STFT and CNN, which can complete motor fault diagnosis tasks more intelligently and accurately. 展开更多
关键词 Big data Deep learning short-time Fouriertransform Convolutional neural network MOTOR
下载PDF
Microstructural evolution in Al–Zn–Mg–Cu–Sc–Zr alloys during short-time homogenization 被引量:6
2
作者 Tao Liu Chun-nian He +3 位作者 Gen Li Xin Meng Chun-sheng Shi Nai-qin Zhao 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2015年第5期516-523,共8页
Abstract: Microstructural evolution in a new kind of aluminum (A1) alloy with the chemical composition of AI-8.82Zn-2.08Mg- 0.80Cu-3.31Sc-0.3Zr was investigated. It is found that the secondary phase MgZn2 is comple... Abstract: Microstructural evolution in a new kind of aluminum (A1) alloy with the chemical composition of AI-8.82Zn-2.08Mg- 0.80Cu-3.31Sc-0.3Zr was investigated. It is found that the secondary phase MgZn2 is completely dissolved into the matrix during a short homogenization treatment (470℃, 1 h), while the primary phase A13(Sc,Zr) remains stable. This is due to Sc and Zr additions into the A1 al- loy, high Zn/Mg mass ratio, and low Cu content. The experimental findings fit well with the results calculated by the homogenization diffusion kinetics equation. The alloy shows an excellent mechanical performance after the short homogenization process followed by hot-extrusion and T6 treatment. Consequently, a good combination of low energy consumotion and favorable mechanical properties is obtained. 展开更多
关键词 aluminum alloys microstructural evolution short-time homogcnization grain refinement
下载PDF
Differentially Expressed Proteome of Microcystis under Short-time Ultrasonic Stress
3
作者 骆灵喜 李彬辉 +1 位作者 林秋月 王波 《Agricultural Science & Technology》 CAS 2017年第8期1371-1373,1415,共4页
This study was conducted to explore the regulation mechanism for key protein expression. The Microcystis treated by short-time ultrasonic wave was select-ed to analyze the total protein based on 2-DE. The results show... This study was conducted to explore the regulation mechanism for key protein expression. The Microcystis treated by short-time ultrasonic wave was select-ed to analyze the total protein based on 2-DE. The results showed that there were 71 up-regulated protein spots, 56 down-regulated protein spots, 54 new protein spots and 21 protein spots disappeared under short-time ultrasonic stress. Eight dif-ferential proteins were chosen for further MALDI-TOFTOF/MS analysis, and the re-sults showed that 2 unknown proteins and 6 functional proteins were detected. These proteins were relevant to some physiological processes, such as antioxidation and anti-inflammatory process, phosphate synthesis and electron transfer, which is beneficial to the metabolic balance and self-protection under short-time ultrasonic stress. 展开更多
关键词 MICROCYSTIS short-time ultrasonic wave Protein expression Two-dimen-sional electrophoresis
下载PDF
Adaptive Short-Time Fractional Fourier Transform Based on Minimum Information Entropy 被引量:2
4
作者 Bing Deng Dan Jin Junbao Luan 《Journal of Beijing Institute of Technology》 EI CAS 2021年第3期265-273,共9页
Traditional short-time fractional Fourier transform(STFrFT)has a single and fixed window function,which can not be adjusted adaptively according to the characteristics of fre-quency and frequency change rate.In order ... Traditional short-time fractional Fourier transform(STFrFT)has a single and fixed window function,which can not be adjusted adaptively according to the characteristics of fre-quency and frequency change rate.In order to overcome the shortcomings,the STFrFT method with adaptive window function is proposed.In this method,the window function of STFrFT is ad-aptively adjusted by establishing a library containing multiple window functions and taking the minimum information entropy as the criterion,so as to obtain a time-frequency distribution that better matches the desired signal.This method takes into account the time-frequency resolution characteristics of STFrFT and the excellent characteristics of adaptive adjustment to window func-tion,improves the time-frequency aggregation on the basis of eliminating cross term interference,and provides a new tool for improving the time-frequency analysis ability of complex modulated sig-nals. 展开更多
关键词 short-time fractional Fourier transform(STFrFT) adaptive algorithm minimum in-formation entropy
下载PDF
An HHT-based method to eliminate short-time strong disturbance from measured signals of bridge 被引量:1
5
作者 王学敏 黄方林 +1 位作者 马广 刘建军 《Journal of Central South University of Technology》 EI 2007年第6期848-852,共5页
According to the characteristic that Hilbert-Huang transform (HHT) can detect abnormity in signals, an HHT-based method to eliminate short-time strong disturbance was proposed. The signal with short-time strong dist... According to the characteristic that Hilbert-Huang transform (HHT) can detect abnormity in signals, an HHT-based method to eliminate short-time strong disturbance was proposed. The signal with short-time strong disturbance was decomposed into a series of intrinsic mode functions (IMFs) and a residue by the empirical mode decomposition (EMD). The instantaneous amplitudes and frequencies of each IMF were calculated. And at abnormal section, instantaneous amplitudes and frequencies were fired according to the data at normal section, replacing the fitted data for the original ones. A new set of IMFs was reconstructed by using the processed instantaneous amplitudes and frequencies. For the residue, abnormal fluctuations could be directly eliminated. And a new signal with the short-time strong disturbance eliminated was reconstructed by superposing all the new IMFs and the residue, The numerical simulation shows that there is a good correlation between the reconstructed signal and the undisturbed signal, The correlation coefficient is equal to 0.999 1. The processing results of the measured strain signal of a bridge with short-time strong disturbance verify the practicability of the method. 展开更多
关键词 short-time strong disturbance Hilbert-Huang transform empirical mode decomposition instantaneous amplitude instantaneous frequency
下载PDF
Characteristics of Radar Echo Parameters and Microphysical Structure Simulation of a Short-Time Heavy Precipitation Supercell 被引量:1
6
作者 ZHAO Gui-xiang WANG Yi-jie LIAN Zhi-luan 《Journal of Tropical Meteorology》 SCIE 2022年第4期388-404,共17页
By using the conventional observations, radar data, NCEP/NCAR FNL 1°×1° reanalysis data and numerical simulation data and with the construction and calculation of radar echo parameters, this paper prese... By using the conventional observations, radar data, NCEP/NCAR FNL 1°×1° reanalysis data and numerical simulation data and with the construction and calculation of radar echo parameters, this paper presents the structural characteristics and physical processes of a short-time heavy precipitation supercell that occurred in the squall line process in Shanxi Province on 24 June 2020. The results show that this squall line event occurred in front of a surface cold front,combined with infiltration of low-level cold air and continuous increase of near-surface humidity in the afternoon. The surface mesoscale convergence line and mesoscale dew point front contributed to the development and systemization of the squall line by a large degree. The short-time extremely heavy precipitation in Pingshun County was caused by the development of a supercell from thunderstorm cells on the front side of the squall line. The characteristics of sharp increase in vertical integral liquid water content, persistent increase in reflectivity factor and continuous rise in the echo top height appeared about 23 min earlier than the severe precipitation, which has qualitative indicating significance for the nowcasting of short-time heavy precipitation. A quantitative analysis of the radar echo parameters suggests that the“sudden drop”of FV40was a precursor signal of cells’ coalescence and rapid development to the mature stage. The areal change of the echo core at the 6 km height was highly subject to the merging and developing of cells, the rapid change of hydrometeor particles in clouds and the precipitation intensity. Changes in the cross-sectional area of convective cells at different heights can indirectly reflect the changes of liquid particles and ice particles in clouds, which is indicatively meaningful for predicting the coalescing and developing-to-maturing of cells and heavy precipitation 30-45 min earlier.A comprehensive echo parameter prediction model constructed by the random forest principle can predict the magnitude of short-time heavy precipitation 40-50 min in advance. Numerical simulation reveals that large amounts of water vapor existed in the near-surface atmosphere, and that the cells rapidly obtained moisture from the ambient atmosphere and developed rapidly through maternal feeding. The cold cloud zone was narrow, upright and had a high stretch height. The upward motion in clouds was strong and deep, and very rich in liquid water content. The graupel particles had a large vertical distribution range, the coexistence area of graupel and snow was large, the height of raindrops was close to the surface with a wide horizontal scale, and the precipitation efficiency was high. These may be the important elements responsible for the occurrence of the short-time heavy precipitation that exceeded historical extreme values. On the basis of the above analyses, a comprehensive parameter(CP) prediction model is worked out, which can estimate the developing trend of supercells and the intensity of short-time heavy precipitation about 1 h in advance. 展开更多
关键词 SUPERCELL short-time heavy rainfall radar echo parameters microphysical structure
下载PDF
Characteristics Analysis on Short-Time Heavy Rainfall during the Flood Season in Shanxi Province, China 被引量:1
7
作者 Xiaoting Tian Dongliang Li +2 位作者 Jinhong Zhou Yaqing Zhou Zexiu Zhang 《Journal of Geoscience and Environment Protection》 2019年第3期190-203,共14页
In order to provide a reference for the correct forecasting of short-term heavy rainfall and better disaster prevention and mitigation services in Shanxi Province, China, it is very important to carry out systematic r... In order to provide a reference for the correct forecasting of short-term heavy rainfall and better disaster prevention and mitigation services in Shanxi Province, China, it is very important to carry out systematic research on short-term heavy precipitation events in Shanxi Province. Based on hourly precipitation data during the flood season (May to September) from 109 meteorological stations in Shanxi, China in 1980-2015, the temporal and spatial variation characteristics of short-time heavy rainfall during the flood season are analyzed by using wavelet analysis and Mann-Kendall test. The results show that the short-time heavy rainfall in the flood season in Shanxi Province is mainly at the grade of 20 - 30 mm/h, with an average of 97 stations having short-time heavy rainfall each year, accounting for 89% of the total stations. The short-time heavy rainfall mainly concentrated in July and August, and the maximal rain intensity in history appeared at 23 - 24 on June 17, 1991 in Yongji, Shanxi is 91.7 mm/h. During the flood season, the short-time heavy rainfalls always occur at 16 - 18 pm, and have slightly different concentrated time in different months. The main peaks of June, July and August are at 16, 17 and 18 respectively, postponed for one hour. Short-time heavy rainfall overall has the distribution that the south is more than the north and the east less than the west in Shanxi area. In the last 36 years, short-time heavy rainfall has a slight increasing trend in Shanxi, but not significant. There is a clear 4-year period of oscillation and inter-decadal variation. It has a good correlation between the total precipitation and times of short-time heavy rainfall during the flood season. 展开更多
关键词 FLOOD SEASON short-time HEAVY RAINFALL Temporal and Spatial Distribution SHANXI PROVINCE
下载PDF
Short-Time Decoherence of Solid-State Qubit at Optimal Operation Points
8
作者 ZHAO Xu LIANG Xian-Ting 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第5X期827-832,共6页
We investigate the short-time decoherence of a solid-state qubit under Ohmic noise at optimal operation points. The decoherence is analyzed by maximum norm of the deviation density operator. It is shown that at the te... We investigate the short-time decoherence of a solid-state qubit under Ohmic noise at optimal operation points. The decoherence is analyzed by maximum norm of the deviation density operator. It is shown that at the temperature T = 3 mK, the loss of the fidelity due to decoherence is much smaller than the DiVincenzo low decoherence criterion, which means that the mode/may be an optimal candidate of qubit for quantum computation. 展开更多
关键词 short-time decoherence Josephson junction qubit ohmic noise
下载PDF
Short-Time Dynamics of the Random n-Vector Model
9
作者 CHEN Yuan LI Zhi-Bing FANG Hai HE Shun-Shan SITU Shu-Ping 《Communications in Theoretical Physics》 SCIE CAS CSCD 2001年第11期611-616,共6页
Short-time critical behavior of the random n-vector model is studied by the theoretic renormalization-group approach.Asymptotic scaling laws are studied in a frame of the expansion in e = 4 - d for n ≠ 1 and for n = ... Short-time critical behavior of the random n-vector model is studied by the theoretic renormalization-group approach.Asymptotic scaling laws are studied in a frame of the expansion in e = 4 - d for n ≠ 1 and for n = 1respectively.In d < 4,the initial slip exponents θ′ for the order parameter and θ for the response function are calculated up to the second order in e = 4 - d for n ≠ 1 and for n = 1 at the random fixed point respectively.Our results show that the random impurities exert a strong influence on the short-time dynamics for d < 4 and n < nc. 展开更多
关键词 n-vector model short-time critical dynamics quenched impurities initial SLIP EXPONENT
下载PDF
Spatial and Temporal Distribution of Different Grades of Short-time Precipitation in Xining City
10
作者 Liang XU Yongling SU 《Meteorological and Environmental Research》 CAS 2023年第1期21-23,共3页
Based on the hourly precipitation data from 4 observation stations of Xining City from June to September during 2005-2011,the temporal and spatial distribution characteristics of short-time precipitation were analyzed... Based on the hourly precipitation data from 4 observation stations of Xining City from June to September during 2005-2011,the temporal and spatial distribution characteristics of short-time precipitation were analyzed.The results show that the precipitation distribution in Xining region exhibited the less-more-less trend from southwest to northeast,while the torrential rain gradually increased from the northwest and southwest to the middle.The hourly general precipitation in Xining region had obviously seasonal characteristics,and its annual distribution showed wavy changes,but the annual variation of short-time heavy precipitation and rainstorm was very obvious.Furthermore,short-time heavy precipitation was concentrated from 18:00 to 24:00,followed by 03:00-07:00 on the following day.The occurrence time of short-time rainstorm accorded with short-time heavy precipitation.It offers a useful reference for the accurate and timely short-term forecast. 展开更多
关键词 DIFFERENT GRADES short-time PRECIPITATION Temporal-spatial DISTRIBUTION
下载PDF
Comparative Analysis of Two Short-time Strong Precipitation Processes
11
作者 CHEN Li-bin GUO Lin +1 位作者 ZHENG Li-xin ZHANG Ling 《Meteorological and Environmental Research》 CAS 2011年第1期19-23,共5页
By means of conceptual model prediction, two short-time strong precipitation processes in Xiamen on June 12th and 14th, 2008 were analyzed from the aspects of real precipitation, weather situation, physical parameter ... By means of conceptual model prediction, two short-time strong precipitation processes in Xiamen on June 12th and 14th, 2008 were analyzed from the aspects of real precipitation, weather situation, physical parameter and radar echo. The results showed that two short-time strong precipitation processes had complete different weather backgrounds, so physical quantities which could reflect atmospheric thermal and dynamic characteristic were different, as well as the characteristic and evolution process of radar echo, and it revealed that two short-time strong precipitation processes in Xiamen had various formation mechanisms and evolution processes. Therefore, many data should be combined to grasp different vantage points in precipitation forecast. 展开更多
关键词 short-time strong precipitation Physical quantity Radar echo China
下载PDF
Application of short-time Fourier transform to high-rise frame structural-health monitoring based on change of inherent frequency over time
12
作者 郭少霞 PEI Qiang 《Journal of Chongqing University》 CAS 2017年第1期1-10,共10页
The high-rise frame structure has become more and more widespread, like its damage from the complication of the environment. The traditional method of damage detection, which is only suitable for the stationary signal... The high-rise frame structure has become more and more widespread, like its damage from the complication of the environment. The traditional method of damage detection, which is only suitable for the stationary signal, does not apply to a high-rise frame structure because its damage signal is non-stationary. Thus, this paper presents an application of the short-time Fourier transform(STFT) to damage detection of high-rise frame structures. Compared with the fast Fourier transform, STFT is found to be able to express the frequency spectrum property of the time interval using the signal within this interval. Application of STFT to analyzing a Matlab model and the shaking table test with a twelve-story frame-structure model reveals that there is a positive correlation between the slope of the frequency versus time and the damage level. If the slope is equal to or greater than zero, the structure is not damaged. If the slope is smaller than zero, the structure is damaged, and the less the slope is, the more serious the damage is. The damage results from calculation based on the Matlab model are consistent with those from the shaking table test, demonstrating that STFT can be a reliable tool for the damage detection of high-rise frame structures. 展开更多
关键词 short-time Fourier transform fast Fourier transform damage identification shaking table test time-frequency analysis
下载PDF
Comparative Analysis of Climate Characteristics of Extremely Short-Time Severe Precipitation in Guizhou Based on Two Types of Rainfall Data
13
作者 Wenyu ZHOU Donghai ZHANG +2 位作者 Dongpo HE Qiuhong HU Xingju WANG 《Meteorological and Environmental Research》 CAS 2021年第1期63-69,74,共8页
In order to fill the gaps of the research on the data of automatic weather stations(referred to as automatic stations)not used for the climate characteristics of extremely short-time severe precipitation in Guizhou Pr... In order to fill the gaps of the research on the data of automatic weather stations(referred to as automatic stations)not used for the climate characteristics of extremely short-time severe precipitation in Guizhou Province,the climate characteristics of extremely short-time severe precipitation in Guizhou Province were compared and analyzed based on the hourly precipitation data of the automatic stations and the national weather stations(referred to as the national stations)from April to September during 2010-2019.The results show that the average state of maximum hourly precipitation of all stations(the automatic stations and the national stations)and national stations both are representative,but the data of all stations are more representative when the maximum hourly precipitation is extreme.The 99.5 th quantile is the most reasonable threshold of extremely short-time severe precipitation in each station.The spatial distribution of extremely short-time severe precipitation intensity in all stations and national stations is generally that the southern region is stronger than the northern region,and the intensity values are concentrated in the range of 40-50 mm/h.All stations data can better reflect the distribution characteristics of<40 and≥50 mm/h.The national stations data underestimates the precipitation intensity in the southern and northeastern marginal areas of Guizhou,and slightly exaggerates the precipitation intensity in the northern part of Guizhou.The monthly and diurnal variations of the frequency of extremely short-time severe precipitation in all stations and national stations are very obvious and the variation trend is the same,but the intensity of extremely short-time severe precipitation has no obvious monthly variation characteristics.There is no significant diurnal variation in the intensity of extremely short-time severe precipitation in all stations,but the diurnal variation in the data of national stations is significant.Since the frequency of extremely short-time severe precipitation in national stations is less,the diurnal variation in the intensity of extremely short-time severe precipitation in all stations is more statistically significant. 展开更多
关键词 Automatic weather station National weather station Extremely short-time severe precipitation Comparative analysis
下载PDF
Relationship between Regional Rainstorm Index and Flood Disaster Ratio of Crop 被引量:8
14
作者 姜会飞 廖树华 +1 位作者 潘学标 候双双 《Agricultural Science & Technology》 CAS 2011年第3期429-434,共6页
According to the daily precipitation data in Beijing area from 1985 to 2008,rainstorm weather index (10.4-38.8 mm) and climate index (daily precipitation ≥27.5 mm) in Beijing area were obtained by using the deter... According to the daily precipitation data in Beijing area from 1985 to 2008,rainstorm weather index (10.4-38.8 mm) and climate index (daily precipitation ≥27.5 mm) in Beijing area were obtained by using the determination method of extreme climate event index recommended by IPCC. Based on rainstorm weather index,rainstorm climate index and national rainstorm standard,the number of rainstorm days and rainfall amount in past years were calculated,and the correlation of annual number of rainy days,rainstorm days,precipitation and rainstorm amount with the flood disaster ratio of crop was analyzed,and the results showed that annual number of rainy days and rainstorm days couldn't reflect flood disaster ratio of crop truly,while annual precipitation and rainstorm amount had obvious linear positive correlation with the flood disaster ratio of crop. In addition,the correlation degree between rainstorm amount calculated by regional climate index and flood disaster ratio of crop was the highest,so it was suggested that rainstorm amount calculated by regional rainstorm climate index could be used to predict and evaluate flood disaster. 展开更多
关键词 rainstorm rainstorm index Number of rainstorm days rainstorm amount Flood disaster
下载PDF
Occurrence Mechanism of A Local Rainstorm in the Northwest of Hubei Province 被引量:7
15
作者 尹恒 李易 +2 位作者 文强 夏金 王立华 《Meteorological and Environmental Research》 CAS 2010年第7期15-18,共4页
A rare local rainstorm weather in the midsummer rainy weather process appeared in the northwest of Hubei Province during July 8-13,2009.The circulation situation,the contributions of dynamic,thermal force and water va... A rare local rainstorm weather in the midsummer rainy weather process appeared in the northwest of Hubei Province during July 8-13,2009.The circulation situation,the contributions of dynamic,thermal force and water vapor to this strong precipitation in this process were discussed.The results showed that the cold air which was brought by Lake Balkis cold vortex was the trigger mechanism of local rainstorm,and Lake Baikal low pressure provided the foreign dynamic for the adjustment of East Asia circulation.When the rainstorm occurred,the divergence in the divergence field had the strong 'pumping effect' in the high altitude.The warm wet airflow in the Bay of Bengal and the South China Sea was the water vapor source of rainstorm.The falling zone of rainstorm appeared in the front of energy frontal zone,and the axis line in the top of high-energy tongue deviated to the side of cold air.Q vector divergence and the negative value zone of water vapor helicity had the important indication effect for the short-term forecast of local rainstorm. 展开更多
关键词 Drought period rainstorm Dynamic and thermal force CONDITION China
下载PDF
Forecast and Analysis of the Rainstorm in Liaoyang on July 15^(th),2008 被引量:2
16
作者 明惠青 杨宝伟 +3 位作者 唐亚平 李岚 孙丽 息涛 《Meteorological and Environmental Research》 CAS 2010年第6期30-32,共3页
By using observation data,numerical forecast product and non-conventional observation data,the process of a rainstorm happened on July 15th,2008 was analyzed. The evolution process of situation field and the predictio... By using observation data,numerical forecast product and non-conventional observation data,the process of a rainstorm happened on July 15th,2008 was analyzed. The evolution process of situation field and the prediction error by numerical forecast products were mainly analyzed. Some local indices for forecasting rainstorm were obtained,so as to guide rainstorm prediction in the future. 展开更多
关键词 rainstorm FORECAST Numerical forecast China
下载PDF
Dry Intrusion Analysis of A Heavy Rainstorm in Southern Shaanxi 被引量:2
17
作者 刘瑞芳 郭大梅 +1 位作者 李萍云 侯建忠 《Meteorological and Environmental Research》 CAS 2010年第12期25-29,共5页
[Objective] One regional rainstorm weather in the south area of Shaanxi was expounded.[Method] By employing the NCEP/NCAR 1°×1°reanalysis data,routine observation and automatic precipitation station dat... [Objective] One regional rainstorm weather in the south area of Shaanxi was expounded.[Method] By employing the NCEP/NCAR 1°×1°reanalysis data,routine observation and automatic precipitation station data,the large scale circulation background field of regional precipitation in the south area of Shaanxi province from July 16-18 in 2010 was expounded.By dint of physical quantity such as the meridional wind,relative humidity and false relative temperature,the characteristics of dry intrusion and its role in rainstorm were expounded.[Result] The mild and high latitude at 500 hPa was stable.The continental high pressure and subtropical high pressure were stable.The 700 and 850 hPa shear lines or low vortexes were the main influence system that resulted into large scale of rainstorm in south Shaanxi.The landing typhoon had distinct influences on the importance of storm.The influence of typhoon and subtropical high was mutual.It not only formed and strengthened the torrent in the low air,also transmitted water vapor and energy incessantly to the south area of Shaanxi,playing an important role in augment of rainstorm.There were two distinct dry intrusions in the rainstorm process,showing a dense dry layer in the high layer of convective layer.The existence of dry layer was conductive to the accumulation of convective unstable energy in the low layer.The release of convective unstable energy could transmit warm and wet airstream in the low level to the higher level,being conductive to the occurrence of precipitation.The analysis of θse in the warp direction vertical profile suggested that there was frontal zone in this rainstorm process and the dry air activity in this rainstorm process was very strong.[Conclusion] The study provided theoretical reference to the forecast in future. 展开更多
关键词 rainstorm Dry air intrusion South area of Shaanxi China
下载PDF
Analysis on the Formation Reason of Regional Rainstorm in Shandong Province during July 8-9,2009 被引量:1
18
作者 赵钢 杨瑞峰 +1 位作者 陈彬 许长山 《Meteorological and Environmental Research》 CAS 2010年第7期41-44,共4页
By using the data which included the conventional weather chart,the satellite cloud image,the regional automatic meteorological station and the new generation of weather radar,the regional strong precipitation process... By using the data which included the conventional weather chart,the satellite cloud image,the regional automatic meteorological station and the new generation of weather radar,the regional strong precipitation process which happened in Shandong Province during July 8-9 in 2009 was analyzed comprehensively.The results showed that Shandong Province was in the strong convergence zone of atmospheric vorticity in the low layer and the ascent zone of vertical velocity.The shear line was generated in the eastward process of northwest vortex,and the ground inverted trough extended to Shandong,which provided the dynamic condition for the formation of rainstorm.The coupling of jet stream in the high-low altitude enhanced the development of convection.The low-altitude jet stream was the main water vapor transportation channel,which provided the water vapor condition for the generation of rainstorm.The water vapor was mainly from the South China Sea and the Bay of Bengal. 展开更多
关键词 rainstorm Water vapor flux Jet stream Pseudoequivalent potential temperature Meso-scale convective system China
下载PDF
Analysis on A Rainstorm and Convective Weather Process 被引量:1
19
作者 张建春 巩婷 马芳 《Meteorological and Environmental Research》 CAS 2010年第10期5-7,共3页
By using NCEP reanalysis data and the routine observation data,a rainstorm and convective weather process which occurred in Tianjin was analyzed.The results showed that the rainstorm occurred in the favorable large sc... By using NCEP reanalysis data and the routine observation data,a rainstorm and convective weather process which occurred in Tianjin was analyzed.The results showed that the rainstorm occurred in the favorable large scale circulation background.The sounding analysis and the physical quantity field analysis could reveal the plentiful water vapor supply condition.The rainstorm had the obvious concomitance relationship with the low level jet.Meanwhile,the existence of warm ridge on the ground was the important condition of convective weather occurrence. 展开更多
关键词 rainstorm Water vapor distribution Low level jet Warm ridge China
下载PDF
Climatic Characteristics Analysis of Flood-producing Rainstorm in Duhe River Basin 被引量:1
20
作者 姚道强 任玮颖 徐茂玲 《Meteorological and Environmental Research》 CAS 2010年第5期12-16,21,共6页
Based on the data from 1998 to 2005,area rainfall,flow of main hydrologic stations in Duhe River and upstream water level of the dam of Huanglongtan Reservoir in the lower reaches of Duhe River were analyzed,and the s... Based on the data from 1998 to 2005,area rainfall,flow of main hydrologic stations in Duhe River and upstream water level of the dam of Huanglongtan Reservoir in the lower reaches of Duhe River were analyzed,and the standard of flood-producing rainstorm in Duhe River was given,while temporal and spatial distribution and circulation flow situation characteristic of flood-producing rainstorm in Duhe River were studied.The results showed that the flood-producing rainstorm in Duhe River was mainly continuous intensive precipitation with the characteristic of long duration.There was most rainfall in Zhuxiquan River,Zhushanguandu River and southwest part of the middle and upper reaches of Duhe River,and next came Zhuxi River.Flood-producing rainstorm occurred in Duhe River with some favorable circulation features.For example,it was more favorable in the west Pacific subtropical high,and the convergence zone at northeast-southwest direction was formed between subtropical high and continental high pressure at 700 hPa,while southwest vortex moved eastward.Low pressure system at 850 hPa in south part of plateau developed and moved eastward to Chongqing region and formed low vortex or shear near Duhe River basin.Moreover,the characteristics of physical quantity field were analyzed,the results showed that temperature in plateau area and the south area of Duhe River basin increased obviously before rainstorm,and east pathway was the main path of cold air which affected flood-producing rainstorm in Duhe River.There was a θse intensive belt with NEE-SWW direction at 30°-40° N at 925-500 hPa,and moisture convergence was beneficial to the occurrence of rainstorm in Duhe River. 展开更多
关键词 Duhe River basin Flood-producing rainstorm Climatic characteristics China
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部