期刊文献+
共找到19篇文章
< 1 >
每页显示 20 50 100
Modified DS np Chart Using Generalized Multiple Dependent State Sampling under Time Truncated Life Test
1
作者 Wimonmas Bamrungsetthapong Pramote Charongrattanasakul 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第3期2471-2495,共25页
This study presents the design of a modified attributed control chart based on a double sampling(DS)np chart applied in combination with generalized multiple dependent state(GMDS)sampling to monitor the mean life of t... This study presents the design of a modified attributed control chart based on a double sampling(DS)np chart applied in combination with generalized multiple dependent state(GMDS)sampling to monitor the mean life of the product based on the time truncated life test employing theWeibull distribution.The control chart developed supports the examination of the mean lifespan variation for a particular product in the process of manufacturing.Three control limit levels are used:the warning control limit,inner control limit,and outer control limit.Together,they enhance the capability for variation detection.A genetic algorithm can be used for optimization during the in-control process,whereby the optimal parameters can be established for the proposed control chart.The control chart performance is assessed using the average run length,while the influence of the model parameters upon the control chart solution is assessed via sensitivity analysis based on an orthogonal experimental design withmultiple linear regression.A comparative study was conducted based on the out-of-control average run length,in which the developed control chart offered greater sensitivity in the detection of process shifts while making use of smaller samples on average than is the case for existing control charts.Finally,to exhibit the utility of the developed control chart,this paper presents its application using simulated data with parameters drawn from the real set of data. 展开更多
关键词 Modified DS np chart generalizedmultiple dependent state sampling time truncated life test Weibull distribution average run length average sample size
下载PDF
Test Stability of Uster Advanced Fiber Information System(AFIS) 被引量:8
2
作者 曹继鹏 鲁琴 +1 位作者 孙鹏子 刘华谱 《Journal of Donghua University(English Edition)》 EI CAS 2010年第3期412-418,共7页
To study test stability of Advanced Fiber Information System(AFIS),card sliver produced in two experiments(12 plans in each experiment)were tested by AFIS.By a statistic analysis of the test results,the number of test... To study test stability of Advanced Fiber Information System(AFIS),card sliver produced in two experiments(12 plans in each experiment)were tested by AFIS.By a statistic analysis of the test results,the number of test times that can get a reliable test reliability(hereinafter this number of test times is referred to as Reliable Test Times,RTT)of test parameters and the coefficient of variation(CV%)values of 30 test results of each experiment plan were obtained.It's concluded that some parameters,such as length,seed coat nep(SCN)size,nep size and immature fiber content(IFC),etc.are very reliable by a test of ten or more times,but other parameters,such as SCN content,trash content,and visible foreign matter(VFM)content,etc.are not reliable until they are tested over 100 times. 展开更多
关键词 Advanced Fiber Information System(AFIS) length NEP impurity reliable test times STABILITY
下载PDF
Validity of subjective assessment as screening tool for dry eye disease and its association with clinical tests 被引量:2
3
作者 Kavita R Bhatnagar Sonali Pote +1 位作者 Sudeep Pujari Dhiraj Deka 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2015年第1期174-181,共8页
AIM: To determine the role of subjective assessment using Mc Monnies dry eye questionnaire in diagnosing dry eye disease and its association with clinical tests.METHODS: There were 500 patients screened for dry eye us... AIM: To determine the role of subjective assessment using Mc Monnies dry eye questionnaire in diagnosing dry eye disease and its association with clinical tests.METHODS: There were 500 patients screened for dry eye using Mc Monnies dry eye questionnaire between May to October 2013 at the outpatient Department of Ophthalmology of a medical college hospital. All 500 patients were subjected to clinical tests. Dry eye was defined as having one or more symptoms often or all the time. Positive signs were if one or both eyes revealed tear film breakup time(TBUT) of ≤10s, a Schirmer test score of ≤10 mm, a Rose Bengal staining score of ≥1, a Lissamine green staining score of ≥1 or existence of meibomian gland disease(≥grade 1). Statistical analysis was performed to describe the distribution of symptoms and signs, to assess the correlations between Mc Monnies score(MS) and variable clinical signs of dry eye, and to explore the association between dry eye symptoms and variable clinical signs. Analysis was performed using software package Epi info. A Probability(P) value using Chi-square test of 【0.005 was taken as significant.· RESULTS: Dry eye prevalence with symptoms(questionnaire), Schirmer test, TBUT, Rose Bengal staining and Lissamine green staining was 25.6%,15.20%, 20.80%, 23.60%, and 22.60% respectively. Among those with severe symptoms(MS】20), 75.86% had a low TBUT(【10s), 58.62% had a low Schirmer’s I test(≤10 mm),86.20% had Rose Bengal staining score of ≥1, 79.31%had Lissamine green staining score of ≥1. We found statistically significant associations between positive Schirmer test and arthritis(P 【0.002), dryness elsewhere(P 【0.001), contact lens use(P 【 0.002), systemic medication(P 【0.0001), sleeping with eyes partly open(P 【0.002), history of dry eyes treatment(P 【0.0001),environmental factors(P 【0.001), swimming(P 【0.001).· CONCLUSION: Subjective assessment plays an important role in diagnosing dry eye disease. There is strong correlation between MS and Schirmer test, TBUT,Rose Bengal staining and Lissamine green staining in normal as well as marginal and pathological dry eye. 展开更多
关键词 Mc Monnies dry eye questionnaire Schirmer test tear film breakup time test Rose Bengal staining Lissamine green staining
下载PDF
Statistical Properties and Confidence Limits about the Mean Time between the Failures (MTBF) in Failure-free Period Life Test (FFPLT)
4
作者 王庆成 《Chinese Quarterly Journal of Mathematics》 CSCD 2001年第1期9-19,共11页
On the basis of strict mathematical description about Failure_Free Period Life Test (FFPLT), the statistical properties of the tests and optimal confidence limit of the parameter are discussed in detail and correspond... On the basis of strict mathematical description about Failure_Free Period Life Test (FFPLT), the statistical properties of the tests and optimal confidence limit of the parameter are discussed in detail and corresponding calculating formulae are found out. 展开更多
关键词 FFPLT MTBF operating characteristic (OC) function expected test time (ETT) maximum likelihood estimation lower confidence limit
下载PDF
A Novel Multiple Dependent State Sampling Plan Based on Time Truncated Life Tests Using Mean Lifetime 被引量:1
5
作者 Pramote Charongrattanasakul Wimonmas Bamrungsetthapong Poom Kumam 《Computers, Materials & Continua》 SCIE EI 2022年第12期4611-4626,共16页
The design of a new adaptive version of the multiple dependent state(AMDS)sampling plan is presented based on the time truncated life test under the Weibull distribution.We achieved the proposed sampling plan by apply... The design of a new adaptive version of the multiple dependent state(AMDS)sampling plan is presented based on the time truncated life test under the Weibull distribution.We achieved the proposed sampling plan by applying the concept of the double sampling plan and existing multiple dependent state sampling plans.A warning sign for acceptance number was proposed to increase the probability of current lot acceptance.The optimal plan parameters were determined simultaneously with nonlinear optimization problems under the producer’s risk and consumer’s risk.A simulation study was presented to support the proposed sampling plan.A comparison between the proposed and existing sampling plans,namely multiple dependent state(MDS)sampling plans and a modified multiple dependent state(MMDS)sampling plan,was considered under the average sampling number and operating characteristic curve values.In addition,the use of two real datasets demonstrated the practicality and usefulness of the proposed sampling plan.The results indicated that the proposed plan is more flexible and efficient in terms of the average sample number compared to the existing MDS and MMDS sampling plans. 展开更多
关键词 Adaptive version of multiple dependent state sampling plan time truncated life test quality level weibull distribution mean lifetime
下载PDF
Topographic tear film trend and new parameters for noninvasive break up time test
6
作者 Yakup Acet 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2022年第12期1932-1939,共8页
AIM:To evaluate the quantitative and qualitative results of the noninvasive tear film break-up time(NI-BUT)test and investigate the predictive ability of the new NIBUT parameter in discriminating between normal Ocular... AIM:To evaluate the quantitative and qualitative results of the noninvasive tear film break-up time(NI-BUT)test and investigate the predictive ability of the new NIBUT parameter in discriminating between normal Ocular Surface Disease Index(OSDI;scores≤12)and abnormal OSDI(scores≥13).METHODS:A total of 341 eyes of 341 volunteers who applied for routine eye outpatient control were included in the prospective study.All participants'noninvasive first tear film break-up time(NIF-BUT),noninvasive average tear film break-up time(NIAvg-BUT)and average value of the first three break-up time(A3F-BUT)were analyzed.A3F-BUT,the new NI-BUT parameter,is calculated by adding the NIF-BUT value to the 2^(nd )break-up time value that has a difference of at most 1 second from the NIF-BUT value and to the 3^(rd) break-up time and then dividing the respective sum by 3.Receiver operating characteristic(ROC)curve and forward logistic regression analyses were performed to determine the parameter that had the best predictive ability between the OSDI groups.RESULTS:The NI-BUT values of 255 eyes of 255 volunteers included in the study were analyzed statistically.The mean NIF-BUT,NIAvg-BUT,and A3F-BUT values were calculated as 5.3±3.0,8±3.1,and 5.8±3.0 seconds,respectively.All three parameters were found to be significantly lower in the abnormal OSDI group(P=0.014,0.034,and 0.011,respectively).The area under the curve(AUC)of the A3F-BUT to predict abnormal OSDI was AUC=0.625(0.529-0.720),P=0.011 and NIF-BUT was AUC=0.599(0.502-0.696),P=0.043.The A3F-BUT parameter and NIF-BUT parameters were found to be significantly efficient in discriminating abnormal OSDI.CONCLUSION:The new parameter for the NI-BUT test has more predictive ability in the discrimination of OSDI groups. 展开更多
关键词 noninvasive break-up time Ocular Surface Disease Index tear film topographic break-up time test
下载PDF
Determination of the Minimum Testing Time for Wireline Formation Testing with the Finite Element Method
7
作者 Hu Falong Xiao Lizhi +1 位作者 Zhang Yuanzhong Wang Chengwei 《Petroleum Science》 SCIE CAS CSCD 2006年第1期39-44,共6页
The wireline formation tester (WFT) is an important tool for formation evaluation, such as calculating the formation pressure and permeability, identifying the fluid type, and determining the interface between oil a... The wireline formation tester (WFT) is an important tool for formation evaluation, such as calculating the formation pressure and permeability, identifying the fluid type, and determining the interface between oil and water. However, in a low porosity and low permeability formation, the supercharge pressure effect exists, since the mudcake has a poor sealing ability. The mudcake cannot isolate the hydrostatic pressure of the formation around the borehole and the mud seeps into the formations, leading to inaccurate formation pressure measurement. At the same time, the tool can be easily stuck in the low porosity/low permeability formation due to the long waiting and testing time. We present a method for determining the minimum testing time for the wireline formation tester. The pressure distribution of the mudcake and the formation were respectively calculated with the finite element method (FEM). The radius of the influence of mud pressure was also computed, and the minimum testing time in low porosity/low permeability formations was determined within a range of values for different formation permeabilities. The determination of the minimum testing time ensures an accurate formation pressure measurement and minimizes possible accidents due to long waiting and testing time. 展开更多
关键词 Wireline formation tester the minimum testing time the finite element method
下载PDF
Area-time associated test cost model for SoC and lower bound of test time
8
作者 张金艺 翁寒一 +1 位作者 黄徐辉 蔡万林 《Journal of Shanghai University(English Edition)》 CAS 2011年第1期43-48,共6页
A novel test access mechanism (TAM) architecture with multi test-channel (TC) based on IEEE Standard 1500 is proposed instead of the traditional sub-TAM structure. The cost model of an area-time associated test an... A novel test access mechanism (TAM) architecture with multi test-channel (TC) based on IEEE Standard 1500 is proposed instead of the traditional sub-TAM structure. The cost model of an area-time associated test and the corresponding lower bound of system-on-chip (SoC) test time are established based on this TAM architecture. The model provides a more reliable method to control the SoC scheduling and reduces the complexity in related algorithm research. The result based on the area time associated test cost model has been validated using the ITC02 test benchmark. 展开更多
关键词 system-on-chip design for testability (SoC DriP) test cost test time lower bound
下载PDF
CORE-UNIFIED SOC TEST DATA COMPRESSION AND APPLICATION
9
作者 Yi Maoxiang Guo Xueying +2 位作者 Liang Huaguo Wang Wei Zhang Lei 《Journal of Electronics(China)》 2010年第1期79-87,共9页
The pattern run-length coding test data compression approach is extended by introducing don't care bit(x) propagation strategy into it.More than one core test sets for testing core-based System-on-Chip(SoC) are un... The pattern run-length coding test data compression approach is extended by introducing don't care bit(x) propagation strategy into it.More than one core test sets for testing core-based System-on-Chip(SoC) are unified into a single one,which is compressed by the extended coding technique.A reconfigurable scan test application mechanism is presented,in which test data for multiple cores are scanned and captured jointly to make SoC test application more efficient with low hardware overhead added.The proposed union test technique is applied to an academic SoC embedded by six large ISCAS'89 benchmarks,and to an ITC' 02 benchmark circuit.Experiment results show that compared with the existing schemes in which a core test set is compressed and applied independently of other cores,the proposed scheme can not only improve test data compression/decompression,but also reduce the redundant shift and capture cycles during scan testing,decreasing SoC test application time effectively. 展开更多
关键词 System-on-Chip(SoC) test application time Pattern run-length X-propagation Union test RECONFIGURATION
下载PDF
Test Vector Optimization Using Pocofan-Poframe Partitionin
10
作者 P.PattunnaRajam Reeba korah G.Maria Kalavathy 《Computers, Materials & Continua》 SCIE EI 2018年第3期251-268,共18页
This paper presents an automated POCOFAN-POFRAME algorithm thatpartitions large combinational digital VLSI circuits for pseudo exhaustive testing. In thispaper, a simulation framework and partitioning technique are pr... This paper presents an automated POCOFAN-POFRAME algorithm thatpartitions large combinational digital VLSI circuits for pseudo exhaustive testing. In thispaper, a simulation framework and partitioning technique are presented to guide VLSIcircuits to work under with fewer test vectors in order to reduce testing time and todevelop VLSI circuit designs. This framework utilizes two methods of partitioningPrimary Output Cone Fanout Partitioning (POCOFAN) and POFRAME partitioning todetermine number of test vectors in the circuit. The key role of partitioning is to identifyreconvergent fanout branch pairs and the optimal value of primary input node N andfanout F partitioning using I-PIFAN algorithm. The number of reconvergent fanout andits locations are critical for testing of VLSI circuits and design for testability. Hence, theirselection is crucial in order to optimize system performance and reliability. In the presentwork, the design constraints of the partitioned circuit considered for optimizationincludes critical path delay and test time. POCOFAN-POFRAME algorithm uses theparameters with optimal values of circuits maximum primary input cone size (N) andminimum fan-out value (F) to determine the number of test vectors, number of partitionsand its locations. The ISCAS’85 benchmark circuits have been successfully partitioned,the test results of C499 shows 45% reduction in the test vectors and the experimentalresults are compared with other partitioning methods, our algorithm makes fewer testvectors. 展开更多
关键词 Pseudo exhaustive testing POCOFAN (Primary Output Cone FanoutPartitioning) POFRAME partitioning combinational digital VLSI circuit testing criticalpath delay testing time design for testability
下载PDF
Mix design method of asphalt rubber open-graded friction course and its application in overlay 被引量:1
11
作者 白琦峰 钱振东 曹荣吉 《Journal of Southeast University(English Edition)》 EI CAS 2009年第3期395-399,共5页
The mix design method of asphalt rubber open-graded friction course (AR-OGFC) by the Marshall test and key technologies of AR-OGFC overlay are studied. Based on the draindown test, the stripping test and the Marshal... The mix design method of asphalt rubber open-graded friction course (AR-OGFC) by the Marshall test and key technologies of AR-OGFC overlay are studied. Based on the draindown test, the stripping test and the Marshall test by different beating times, the asphalt content estimating method and Marshall beat criterion are studied. It is found that the asphalt content of AR-OGFC can be estimated by the formula of Arizona, and the proper Marshall test criterion for AR-OGFC is 50 beats on both sides. By analyzing the influence of gradation on OGFC performance, the gradation of AR-OGFC is recommended, and the amount of aggregate passing 4. 75 mm should be minimized for AR-OGFC. Through investigation of AR-OGFC overlay projects, key technologies such as the treatment of underlying pavement and the selection of tack coat are advanced, and modified emulsified asphalt should be used in AR-OGFC overlay tack coat. 展开更多
关键词 asphalt rubber open-graded friction course beat time of Marshall test tack coat
下载PDF
Retrospective study of effect of whole-body vibration training on balance and walking function in stroke patients 被引量:9
12
作者 Lei Xie Shi-Xiong Yi +2 位作者 Qi-Feng Peng Pei Liu Heng Jiang 《World Journal of Clinical Cases》 SCIE 2021年第22期6268-6277,共10页
BACKGROUND Dysfunction in stroke patients has been a problem that we committed to solve and explore.Physical therapy has some effect to regain strength,balance,and coordination.However,it is not a complete cure,so we ... BACKGROUND Dysfunction in stroke patients has been a problem that we committed to solve and explore.Physical therapy has some effect to regain strength,balance,and coordination.However,it is not a complete cure,so we are trying to find more effective treatments.AIM To observe the effect of whole-body vibration training(WVT)on the recovery of balance and walking function in stroke patients,which could provide us some useful evidence for planning rehabilitation.METHODS The clinical data of 130 stroke participants who underwent conventional rehabilitation treatment in our hospital from January 2019 to August 2020 were retrospectively analyzed.The participants were divided into whole-body vibration training(WVT)group and non-WVT(NWVT)group according to whether they were given WVT.In the WVT group,routine rehabilitation therapy was combined with WVT by the Galileo Med L Plus vibration trainer at a frequency of 20 Hz and a vibration amplitude of 0+ACY-plusmn+ADs-5.2 mm,and in the NWVT group,routine rehabilitation therapy only was provided.The treatment course of the two groups was 4 wk.Before and after treatment,the Berg balance scale(BBS),3 m timed up-and-go test(TUGT),the maximum walking speed test(MWS),and upper limb functional reaching(FR)test were performed.RESULTS After 4 wk training,in both groups,the BBS score and the FR distance respectively increased to a certain amount(WVT=46.08±3.41 vs NWVT=40.22±3.75;WVT=20.48±2.23 vs NWVT=16.60±2.82),with P<0.05.Furthermore,in the WVT group,both BBS score and FR distance(BBS:18.32±2.18;FR:10.00±0.92)increased more than that in the NWVT group(BBS:13.29±1.66;FR:6.16±0.95),with P<0.05.Meanwhile,in both groups,the TUGT and the MWS were improved after training(WVT=32.64±3.81 vs NWVT=39.56±3.68;WVT=12.73±2.26 vs NWVT=15.04±2.27,respectively),with P<0.05.The change in the WVT group(TUGT:17.49±1.88;MWS:6.79±0.81)was greater than that in the NWVT group(TUGT:10.76±1.42;MWS:4.84±0.58),with P<0.05.CONCLUSION The WVT could effectively improve the balance and walking function in stroke patients,which may be good for improving their quality of life. 展开更多
关键词 Balance function Berg balance scale Maximum walking speed test Stroke Timed up-and-go test Vibration training
下载PDF
Quality Analysis of Dairy Herd Improvement Data from Henan Province 被引量:1
13
作者 Zhen ZHANG Xiaoli REN +3 位作者 Lei YAN Yuefei YAN Fanjun GENG Yanqin SUN 《Agricultural Science & Technology》 CAS 2017年第1期151-155,188,共6页
The dairy herd improvement data from Henan Province were analyzed statistically to establish screening criteria for relevant data, thereby laying a foundation for genetic evaluation of dairy cows. With the 2 152 451 t... The dairy herd improvement data from Henan Province were analyzed statistically to establish screening criteria for relevant data, thereby laying a foundation for genetic evaluation of dairy cows. With the 2 152 451 test-day records about 155 893 Chinese Holstein dairy cows collected by the Henan Dairy Herd Improvement Center from January 2008 to April 2016, the dynamics of test times during a complete lactation, test interval during a complete lactation, days in milk (DIM) of first test-day record, daughter descendant number and herd number of bull, age at first calving and pedigree integrity rate among different years and different herd sizes were analyzed by MEANS order of SAS 9.4. In addition, the data that were applicable to genetic evaluation were screened by SQL program. The results showed that during 2008-2015, the number of cow individuals participating in DHI in Henan Province increased from 7 379 to 93 706; the test-day milk yield increased from 19.91 to 24.05 kg; the somatic cell count reduced from 411.09×10^3 to 277.08×10^3 cells/ml; the percentage of cows with DIM ranging from 5-305 d reached 70.92%; the average test times increased from 3.20 to 6.31 times; the test interval decreased from 70.22 to 33.83 d; the dairy cows with age at first calving of 25 months were dominant, accounting for 12.57%; the bulls whose daughter descendant number was 20 or more and the daughters were distributed in 10 or more farms accounted for 6.05%; the one-generation pedigree integrity rate was 82.54%; the percentage of data that could be used for genetic evaluation was screened as 20.67%, which was lower than the results of other similar studies. 展开更多
关键词 Dairy herd improvement data quality test times test interval DIM of first test-day record Daughter descendant number and herd number of bull age at first calving Pedigree integrity rate
下载PDF
THE REAL IN TIME CT MONITORING OF THE MESO-DAMAGE EVOLUTION LAW OF SANDSTONE UNDER TRIAXIAL COMPRESSION 被引量:2
14
作者 任建喜 史姝杰 刘文刚 《Journal of Coal Science & Engineering(China)》 2000年第2期19-26,共8页
The real in time computerized tomography (CT) testing of the meso damage propagation law of the whole sandstone failure process under triaxial compression has been completed using the newest specified triaxial loading... The real in time computerized tomography (CT) testing of the meso damage propagation law of the whole sandstone failure process under triaxial compression has been completed using the newest specified triaxial loading equipment corresponding to the CT machine. Through the CT scanning, the clear CT images which include from the microcracks compressed stage to growth stage, bifurcation stage, development stage, crack fracture stage,the rock sample failure until to unloading stage in the different stress states were obtained. The CT values, CT images and the other data have been analyzed. Based on the results of the CT testing of meso damage evolution law of rock,the stress threshold value of meso damage of rock is given, and the stress strain complete process curve of rock is divided into some sections. The initial rock damage propagation law is given in this paper. 展开更多
关键词 SANDSTONE real in time of CT testing damage propagation meso scale CT value
全文增补中
Testing Times
15
作者 HU YUE 《Beijing Review》 2008年第24期20-21,共2页
After uniting in its earthquake rescue efforts,China now faces a new test-rebuilding the homes of millions Zhu Jing had never expected to fall into such dire straits: She has nowhere to go,
关键词 testing Times
原文传递
Standing the Test of Time
16
作者 YUAN YUAN 《Beijing Review》 2009年第45期44-45,共2页
Seal engraving, a pearl of Chinese traditional arts, has been included on the world intangible cultural heritage
关键词 Standing the test of Time
原文传递
A TEST OF TIME
17
作者 An Gang 《Beijing Review》 2018年第50期20-21,共2页
When the working dinner between Chinese President Xi Jinping and U.S. President Donald Trump ended after the G20 Summit in Buenos Aires on December 1, Chinese State Councilor and Foreign Minister Wang Yi told the medi... When the working dinner between Chinese President Xi Jinping and U.S. President Donald Trump ended after the G20 Summit in Buenos Aires on December 1, Chinese State Councilor and Foreign Minister Wang Yi told the media that the meeting has"chartered the course for China-U.S. relations" with the two presidents reaching an important common understanding. 展开更多
关键词 A test OF TIME
原文传递
Will the Three Gorges Dam Stand The Test of Time?
18
《Beijing Review》 2010年第32期46-47,共2页
After successfully containing the biggest flood this century, the Three Gorges Dam,on the upper reaches of the Yangtze River in central China’s Hubei Province, has encountered another flood, that of public opinion:Wi... After successfully containing the biggest flood this century, the Three Gorges Dam,on the upper reaches of the Yangtze River in central China’s Hubei Province, has encountered another flood, that of public opinion:Will this dam be able to hold floods that are "once-in-10,000-years" or "once-in-1,000-years" or "once-in-a-century"? Should numerous hazards this year, including land and mudslides and mountain torrents,be blamed on accumulation of sediment caused by the construction of the Three Gorges Dam? To get answers to these questions,journalists from Xinhua News Agency interviewed Cao Guangjing, Board Chairman of the China Three Gorges Corp., the operator of the Three Gorges Dam. 展开更多
关键词 Will the Three Gorges Dam Stand The test of Time
原文传递
Inter-annual variations in vegetation and their response to climatic factors in the upper catchments of the Yellow River from 2000 to 2010 被引量:20
19
作者 CAO Ran JIANG Weiguo +3 位作者 YUAN Lihua WANG Wenjie LV Zhongliang CHEN Zheng 《Journal of Geographical Sciences》 SCIE CSCD 2014年第6期963-979,共17页
To understand the variations in vegetation and their correlation with climate factors in the upper catchments of the Yellow River, China, Normalized Difference Vegetation Index(NDVI) time series data from 2000 to 20... To understand the variations in vegetation and their correlation with climate factors in the upper catchments of the Yellow River, China, Normalized Difference Vegetation Index(NDVI) time series data from 2000 to 2010 were collected based on the MOD13Q1 product. The coefficient of variation, Theil–Sen median trend analysis and the Mann–Kendall test were combined to investigate the volatility characteristic and trend characteristic of the vegetation. Climate data sets were then used to analyze the correlation between variations in vegetation and climate change. In terms of the temporal variations, the vegetation in this study area improved slightly from 2000 to 2010, although the volatility characteristic was larger in 2000–2005 than in 2006–2010. In terms of the spatial variation, vegetation which is relatively stable and has a significantly increasing trend accounts for the largest part of the study area. Its spatial distribution is highly correlated with altitude, which ranges from about 2000 to 3000 m in this area. Highly fluctuating vegetation and vegetation which showed a significantly decreasing trend were mostly distributed around the reservoirs and in the reaches of the river with hydropower developments. Vegetation with a relatively stable and significantly decreasing trend and vegetation with a highly fluctuating and significantly increasing trend are widely dispersed. With respect to the response of vegetation to climate change, about 20–30% of the vegetation has a significant correlation with climatic factors and the correlations in most areas are positive: regions with precipitation as the key influencing factor account for more than 10% of the area; regions with temperature as the key influencing factor account for less than 10% of the area; and regions with precipitation and temperature as the key influencing factors together account for about 5% of the total area. More than 70% of the vegetation has an insignificant correlation with climatic factors. 展开更多
关键词 correlation analysis coefficient of variation hydropower development Mann–Kendall test NDVI time series data Theil–Sen median trend analysis Yellow River China
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部