期刊文献+
共找到1,519篇文章
< 1 2 76 >
每页显示 20 50 100
Differentiation degree combination weighting method for investment decision-making risk assessment in power grid construction projects 被引量:5
1
作者 Yuan Chang Chenmiao Liu +4 位作者 Minghua Liu Wenxia Liu Zongqi Liu Heng Zhang Yan Zheng 《Global Energy Interconnection》 2019年第5期466-478,共13页
Power grid construction projects are distinguished by their wide variety,high investment,long payback period,and close relation to national development and human welfare.To improve the investment accuracy in such proj... Power grid construction projects are distinguished by their wide variety,high investment,long payback period,and close relation to national development and human welfare.To improve the investment accuracy in such projects and effectively prevent investment risks,this paper proposes an investment optimization decision-making method for multiple power grid construction projects under a certain investment scale.Firstly,an in-depth analysis of the characteristics and development requirements of China’s power grid projects was performed.Thereafter,the time sequence and holographic method was adopted to conduct multi-dimensional,multi-perspective risk assessment of different parts of power grid projects,and a holographic risk assessment index system was developed.Moreover,an investment decision model considering the comprehensive risk based on combination weighting was developed according to the output and input of power grid construction projects.A new combination weighting optimization method that takes into account the investment willingness of enterprises was designed to improve the current weighting evaluation methods.Finally,the validity and applicability of the proposed evaluation method were verified by case examples. 展开更多
关键词 Power GRID PROJECTS Risk assessment Time SEQUENCE index system combination weighting
下载PDF
Universal Index Formula of Parameterized Combination Operator for Eco-environmental Quality Evaluation
2
作者 YU Chun-xue LI Zuo-yong TIAN Wen-xin 《Meteorological and Environmental Research》 CAS 2011年第8期74-77,共4页
[Objective] The aim was to evaluate the regional eco-environmental quality by using the universal index formula of parameterization combination operator based normalized index values.[Method] Through setting reference... [Objective] The aim was to evaluate the regional eco-environmental quality by using the universal index formula of parameterization combination operator based normalized index values.[Method] Through setting reference values and normalized transformation formulae for typical ecological environmental indexes appropriately,the difference among the standard normalized values would become very small after normalized transformation,and the ecological environmental indices expressed by normalized values can be equivalent to normalized indices.Under certain optimization conditions,shuffled frog leaping based on immune evolutionary particle swarm optimization algorithm was applied to optimize the parameters in parameterization combination operator formula,and the universal index formula suited to eco-environmental quality assessment was established finally.[Result] The universal index formula of parameterization combination operator,appropriate for any m(1≤m≤23) ecological environmental indices,was used to assess the eco-environmental quality of towns surrounding Headland Reservoir,and the results were in full accordance with those of unascertained measure method,that is,the eco-environmental quality of five towns around Headland Reservoir was the fourth grade.[Conclusion]The universal index formula of parameterization combination operator,suited to eco-environmental quality evaluation,is simple and intuitive in form,easy in computation and universal in application. 展开更多
关键词 NORMALIZATION Eco-environmental quality evaluation Parameterization combination operator Universal index formula China
下载PDF
Combined Pollution and Pollution Index of Heavy Metals in Red Soil 被引量:56
3
作者 CHEN HUAIMAN ZHENG CHUNRONG WANG SHENQIANG and TU CONG(Institute of Soil Science, the Chinese Academy of Sciences, P.O. Box 821, Naroing 210008 China) 《Pedosphere》 SCIE CAS CSCD 2000年第2期117-124,共8页
A field experiment was conducted to study the effects of Pb, Cd, Cu, Zn and As coexisting in red soilon growth of rice (Oryza sativa L.), mung bean (Vigna rabiata (Linn.) Wilczek), alfalfa (Medicago sativaL.), slash p... A field experiment was conducted to study the effects of Pb, Cd, Cu, Zn and As coexisting in red soilon growth of rice (Oryza sativa L.), mung bean (Vigna rabiata (Linn.) Wilczek), alfalfa (Medicago sativaL.), slash pine (Pinus elliottii Engelm.) and aspen (Populus L.). Results showed that rice, mung bean andalfalfa were significantly innuenced by combined pollution of the heavy metals. The contents of Pb, cd andAs in rice grains greatly exceeded the National Standards for Food Hygiene of China. Heavy metals at ahigh concentration seriously retarded growth of mung bean and alfalfa, but not so obviously with slash pineand aspen. The composite index is suggested for evaluating the relativity of combined pollution witll heavymetals in soil. 展开更多
关键词 combined pollution composite pollution index plant growth red soil
下载PDF
Food-Security Indexes Related to Combined Pollution of Chromium and Phenol in Soil-Rice Systems 被引量:9
4
作者 ZHOUQIXING ZHUYINMEI 《Pedosphere》 SCIE CAS CSCD 1997年第1期15-24,共10页
The pot-culture method combined with chemical and statistical analyses was used to get basic data for determination of the food-security indexes related to combined pollution of Cr and phenol in soil-rice systems.Regr... The pot-culture method combined with chemical and statistical analyses was used to get basic data for determination of the food-security indexes related to combined pollution of Cr and phenol in soil-rice systems.Regression analyses according to the experimental result indicated that the critical concentrations of Cr andphenol in brown rice were 0.37 and 0.33 mg kg-1, respectively, under the condition of Cr-phenol combined pollution. 展开更多
关键词 CHROMIUM combined pollution food-security index PHENOL soil-rice system
下载PDF
Representation of the ENSO Combination Mode and its Asymmetric SST Response in Different Resolutions of HadGEM3
5
作者 Jianghua WAN Hongli REN Peili WU 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2018年第8期167-180,共14页
Previous studies have revealed a combination mode (C-mode) occurring in the Indo-Pacific region, arising from nonlinear interactions between ENSO and the western Pacific warm pool annual cycle. This paper evaluates ... Previous studies have revealed a combination mode (C-mode) occurring in the Indo-Pacific region, arising from nonlinear interactions between ENSO and the western Pacific warm pool annual cycle. This paper evaluates the simulation of this C-mode and its asymmetric SST response in HadGEM3 and its resolution sensitivity using three sets of simulations at horizontal resolutions of N96, N216 and N512. The results show that HadGEM3 can capture well the spatial pattern of the C-mode associated surface wind anomalies, as well as the asymmetric response of SST in the tropical Pacific, but it strongly overestimates the explained variability of the C-mode compared to the ENSO mode. The model with the three resolutions is able to reproduce the distinct spectral peaks of the C-mode at the near annual combination frequencies, but the performance in simulating the longer periods is not satisfactory, presumably due to the unrealistic simulation of the ENSO mode. Increasing the horizontal resolution can improve the consistency between atmospheric and oceanic representations of the C-mode, but not necessarily enhance the accuracy of C-mode simulation compared with observation. 展开更多
关键词 ENSO combination mode asymmetric response Nifio-A index HadGEM3 horizontal resolution
下载PDF
Meat Production Performances of Geese in Different Crossbred Combinations
6
作者 TANG Qing-ping ZHANG Shuang-jie +2 位作者 GUO Jun xu Guo-yin TAN Wei-zhong 《Animal Husbandry and Feed Science》 CAS 2010年第1期4-7,共4页
[ Objective] To study the meat production performance of geese in different crossbred combination, and provide a reference for cultivating new multiplication strains of meat geese. [Method] A total of five goose breed... [ Objective] To study the meat production performance of geese in different crossbred combination, and provide a reference for cultivating new multiplication strains of meat geese. [Method] A total of five goose breeds including Taihu goose (T), Wulong goose (WL), Wanxi white goose (WX), Sichuan white goose (SC) and Sanhua goose (SH) were used as research objects, and eight crossbred combinations were designed. The body measurements, slaughter performance, conventional meat quality and muscle composition of 90-day-old geese in eight crossbred combinations were determined and comparatively analyzed. [ Result] All the body measurement indexes except thud width of WXSC combination were the biggest in the eight crossbred combinations. Contrarily, the body measurement indexes of SHSC combination, including average body weight, body slope length, breast depth, breast width, shank length, neck length and half-diving depth were the lowest in the eight crossbred combinations. The live weight, slaughter weight and abdomen fat weight of WXSC combinations ware 3 291.36, 2 956.46 and 77.84 g, respectively, which were the biggest in eight crossbred combinations. The slaughter rate of SHWL combinations was 92.96%, and more than other crossbred combinations. The shear force of SHT and WXWL combinations were the lowest (3.09 kg) and the highest (3.78 kg), respectively. The water holding capacities of SCWL and WXSC combinations were the highest (66.46%) and the lowest (61.48%), respectively. The percentage of moisture content of SHWL and SCT combinations were the highest (73.05%) and the lowest (66.77%), respectively. The crude protein content of SHT and SHWL combinations were the highest (23.32%) and the lowest (21.94%), respectively. The percentage of crude fat content of SHT and SCWL combinations were the highest (3.06%) and the lowest (1.67%), respectively. [ Concusion] The growth rate of WXSC combination is the fastest, and the meat performance of SHT combination is the best. 展开更多
关键词 GOOSE Crossbred combination Body measurement indexes Slaughter performances Meat quality
下载PDF
Risk factors and ankle brachial indexes in cerebral infarction combined with peripheral arterial disease
7
作者 Huihua Liu Jun Wang 《Neural Regeneration Research》 SCIE CAS CSCD 2006年第7期653-656,共4页
BACKGROUND: Ankle brachial index (ABI) is widely involved in researches and clinical application of peripheral vascular injury of patients with diabetes mellitus (DM); however, the application in cerebral infarction (... BACKGROUND: Ankle brachial index (ABI) is widely involved in researches and clinical application of peripheral vascular injury of patients with diabetes mellitus (DM); however, the application in cerebral infarction (CI) is rare. OBJECTIVE: To investigate the possible risk factor of cerebral infarction plus peripheral arterial disease (PAD), compare metabolic characteristics of patients who having CI plus PAD or only having CI, and understand the significance of ABI on screening and diagnosing CI plus PAD of lower limb. DESIGN: Contrast observation based on CI patients. SETTING: Department of Neurology, Nanxishan Hospital of Guangxi Zhuang Autonomous Region. PARTICIPANTS: A total of 124 CI patients were selected from Department of Neurology, Nanxishan Hospital of Guangxi Zhuang Autonomous Region from July 2005 to April 2006, including 72 males and 52 females aged from 45 to 88 years. All patients met the diagnostic criteria of cerebrovascular disease established by National Academic Conference of Cerebrovascular Diseases in 1995 and determined as cerebral infarction with MRI or CT examination. All patients provided informed consent. There were 46 cases (37.2%) with CI plus PAD and 78 cases (62.8%) only with CI. METHODS: Blood pressure of bilateral ankles and upper extremities was measured at plain clinostatism with DINAMAP blood pressure monitor (GE Company). The ratio between average systolic pressure of lateral ankle and average systolic pressure of both upper extremities was regarded as ABI. The normal ABI was equal to or more than 0.9. If ABI < 0.9 occurred at one side, patients were diagnosed as PAD. On the second morning after hospitalization, blood was collected to measure fasting blood glucose (FBG), 2-hour postprandial blood glucose (PBG2h), glycosylated hemoglobin (HbA1c), triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C). Among them, blood glucose, lipid and other biochemical markers were measured with enzyme chemistry assay and HbA1c was measured with HbA1c meter based on high liquid phase. Measurement data and enumeration data were compared with t test and Chi-square test, and multiple factors were dealt with Logistic regression analysis and multivariate linear regression analysis. MAIN OUTCOME MEASURES: Results of correlation between ABI and metabolic markers with multivariate linear regression analysis; risk factors of CI plus PAD with Logistic regression analysis; comparisons of metabolic markers between PAD and non-PAD patients. RESULTS: All 124 patients with acute CI were involved in the final analysis. ① Comparisons of metabolic markers: Levels of serum LDL-C and uric acid (UA) were higher of PAD patients than those of non-PAD patients (t =2.051 9, 3.339 1, P < 0.05); however, there were no significant differences among other metabolic markers (P > 0.05). ② Results of multivariate linear regression analysis: PBG2h, LDL-C and UA were obvious correlation with ABI of posterior tibial artery of lower limb and dorsal pedis artery (partial regression coefficient = -0.231 to -1.010, P < 0.05). ③ Risk factors of CI plus PAD with Logistic regression analysis: Age, smoking history, sum of CI focus (≥3) and LDL-C were independent risk factor of CI plus PAD (OR =1.524-5.422, P < 0.05-0.01). CONCLUSION: ① Levels of serum LDL-C and UA of patients with CI plus PAD are high. ② ABI of lower limbs is correlation with PBG2h, LDL-C and UA. In addition, measuring ABI is beneficial for early diagnosing PAD of lower limbs of patients who have poorly controlled blood glucose, abnormal lipid and poor renal function. ③ Age, LDL-C and sum of CI focus (≥3) are independent risk factors of CI plus PAD. It is of significance for screening non-PAD patients to evaluate risk degrees and prognosis and select therapeutic methods based on ABI measurement. 展开更多
关键词 PAD ABI Risk factors and ankle brachial indexes in cerebral infarction combined with peripheral arterial disease
下载PDF
A new hybrid method with data‑characteristic‑driven analysis for artificial intelligence and robotics index return forecasting
8
作者 Yue‑Jun Zhang Han Zhang Rangan Gupta 《Financial Innovation》 2023年第1期2019-2041,共23页
Forecasting returns for the Artificial Intelligence and Robotics Index is of great significance for financial market stability,and the development of the artificial intelligence industry.To provide investors with a mo... Forecasting returns for the Artificial Intelligence and Robotics Index is of great significance for financial market stability,and the development of the artificial intelligence industry.To provide investors with a more reliable reference in terms of artificial intelligence index investment,this paper selects the NASDAQ CTA Artificial Intelligence and Robotics(AIRO)Index as the research target,and proposes innovative hybrid methods to forecast returns by considering its multiple structural characteristics.Specifically,this paper uses the ensemble empirical mode decomposition(EEMD)method and the modified iterative cumulative sum of squares(ICSS)algorithm to decompose the index returns and identify the structural breakpoints.Furthermore,it combines the least-square support vector machine approach with the particle swarm optimization method(PSO-LSSVM)and the generalized autoregressive conditional heteroskedasticity(GARCH)type models to construct innovative hybrid forecasting methods.On the one hand,the empirical results indicate that the AIRO index returns have complex structural characteristics,and present time-varying and nonlinear characteristics with high complexity and mutability;on the other hand,the newly proposed hybrid forecasting method(i.e.,the EEMD-PSO-LSSVM-ICSS-GARCH models)which considers these complex structural characteristics,can yield the optimal forecasting performance for the AIRO index returns. 展开更多
关键词 Artificial Intelligence and Robotics index return forecasting PSO-LSSVM model GARCH model Decomposition and integration model combination model
下载PDF
Association between Systolic Blood Pressure Difference ≥10 mm Hg and Ankle-Brachial Index
9
作者 Shinji Maeda Yuzo Okumura Naohiko Hara 《International Journal of Clinical Medicine》 2016年第5期361-369,共9页
Background: In new outpatients, blood pressure should be measured in both arms. A previous study reported that an inter-arm systolic blood pressure difference (ΔSBP) of ≥10 mm Hg is associated with an increased risk... Background: In new outpatients, blood pressure should be measured in both arms. A previous study reported that an inter-arm systolic blood pressure difference (ΔSBP) of ≥10 mm Hg is associated with an increased risk of mortality. Aim: The aim was to identify the associations with absolute values of ΔSBP (|ΔSBP|) ≥10 mm Hg. Subjects and Methods: This study included 2481 patients. Patients with a body mass index ≥25 kg/m<sup>2</sup> were defined as obese. The group of A was defined as following: ankle-brachial index (ABI) was <0.9 or ≥1.3. ΔSBP was expressed as right arm BP minus left arm BP. |ΔSBP| ≥10 mm Hg were analyzed using multivariate logistic analysis. Results: |ΔSBP| ≥10 mm Hg was found in 6.0% of patients and |ΔSBP| < 5 mm Hg in 80.4%. In multivariate analysis, the odds ratios (ORs) of the associations with |ΔSBP| ≥10 mm Hg were significantly associated with abnormal ABI and obesity regardless of sex and age. Moreover, the OR of the combined effects of abnormal ABI and obesity was higher than that of abnormal ABI and obesity alone. Conclusion: |ΔSBP| ≥10 mm Hg was associated with abnormal ABI and obesity. In a primary care setting, blood pressure should be actively measured in both arms. This study suggests that the associations with |ΔSBP| ≥10 mm Hg may be a useful part of screening for abnormal ABI. 展开更多
关键词 Systolic Blood Pressure Difference Ankle-Brachial index OBESITY Odds Ratio combined Effects
下载PDF
Identification of Probable Type of Bituminous Mix Depending on Higher Combined Index of Stone Aggregates
10
作者 Mohamed Ilyas Anjum 《Journal of Mechanics Engineering and Automation》 2011年第5期398-400,共3页
The stone aggregates constitute over 90% of the mass of a pavement and hence its properties play a very vital role in design of satisfactory unbound as well as bituminous mixes. Also since the aggregates availability ... The stone aggregates constitute over 90% of the mass of a pavement and hence its properties play a very vital role in design of satisfactory unbound as well as bituminous mixes. Also since the aggregates availability is continuously becoming scarce, attempts have to be made to identify use of some marginal as well as inferior aggregates without sacrificing the desirable qualities of resulting mixes. One of the most important properties therefore is the combined index of aggregates which deals with aggregates shape and is the sum of flakiness and elongation indices of aggregates measured related to their thickness and length respectively. The Ministry of Road Transport and Highways (MoRTH) specifies an upper limit of 30% combined index for different types of bituminous mixes. In the field, many times the aggregates supplied have combined index of more than 30%. A pre determined mix such as bituminous concrete, dense or semi dense bituminous macadam etc. has to be designed using such aggregates. It may be easy to design the mix but to get the aggregates with desirable combined index is often very difficult. In order to overcome this, in many projects, secondary crushers are used to crush the aggregates for the second time just to bring down the combined index. This obviously increases the project cost. It is quite possible that the aggregates with higher combined index may be suitable for a particular type of mix. It is therefore appropriate to study what type of a bituminous mix can be satisfactorily prepared depending on the availability of aggregates with generally higher values of combined index. Hence, it was attempted to determine the usual Marshall test properties of two most commonly used types of bituminous mixes namely bituminous concrete and dense bituminous macadam using aggregates with combined index 30%, 40% and 50%. It was found that aggregates with higher combined index are more suitable to design dense bituminous macadam mix than bituminous concrete. 展开更多
关键词 combined index DBM (dense bituminous macadam) BC (bituminous concrete) bituminous mix properties.
下载PDF
Combined pollution of Cd and Zn in soil-rice systems and its indexes
11
作者 ZHOU Qixing and WANG Fengping,Dept of Environmental Sciences,Zhejiang Agri Univ,Hangzhou 310029,China 《Chinese Rice Research Newsletter》 1996年第3期11-12,共2页
Due to the mining,smelting,sewage irriga-tion,agricultural runoff,and development ofrural enterprises,combined pollution of Cd andZn in soil-rice systems has frequently oc-curred.This problem was studied by using thep... Due to the mining,smelting,sewage irriga-tion,agricultural runoff,and development ofrural enterprises,combined pollution of Cd andZn in soil-rice systems has frequently oc-curred.This problem was studied by using thepot-culture imitative method combined withhemical analysis and mathematical models. 展开更多
关键词 ZN CD combined pollution of Cd and Zn in soil-rice systems and its indexes SOIL
下载PDF
基于CI指数的淮河流域干旱时空特征研究 被引量:30
12
作者 谢五三 田红 +1 位作者 王胜 唐为安 《气象》 CSCD 北大核心 2013年第9期1171-1175,共5页
本文运用淮河流域170个气象台站1961—2010年共50年逐日气温、降水资料以及历史干旱灾情资料,研究CI指数在淮河流域的区域适应性,并以此为基础运用多种统计方法分析淮河流域近50年的干旱时空特征。结果表明:基于CI指数计算得到的历年干... 本文运用淮河流域170个气象台站1961—2010年共50年逐日气温、降水资料以及历史干旱灾情资料,研究CI指数在淮河流域的区域适应性,并以此为基础运用多种统计方法分析淮河流域近50年的干旱时空特征。结果表明:基于CI指数计算得到的历年干旱日数与受灾面积和成灾面积的相关性通过了0.01的显著性水平检验,表明CI指数在淮河流域具有较好的区域适应性。淮河流域年均干旱日数基本呈纬向空间分布,流域北部多于南部;流域东部和西部的干旱日数略有增多趋势,而中部和北部的干旱日数有减少趋势,但均未通过0.05的显著性水平检验;EOF前3个模态累积方差贡献达94.4%,前3个分布型依次为全流域干旱日数一致多或少型、南北相反型以及东西相反型;1961年以来干旱日数共经历了由少到多4个循环交替,目前正处于相对偏少期;M-K突变检验表明近50年来淮河流域干旱日数没有明显的突变。 展开更多
关键词 ci指数 干旱特征 适应性 淮河流域
下载PDF
基于CI指数的陕西干旱时空变化特征分析 被引量:23
13
作者 蔡新玲 叶殿秀 +2 位作者 李茜 张存杰 王娜 《干旱地区农业研究》 CSCD 北大核心 2013年第5期1-8,共8页
利用1961—2010年陕西省72个气象站逐日气温和降水资料,采用综合气象干旱指数法,统计分析了近50年陕西省气象干旱发生的时空分布特征。结果表明:陕西省年及四季干旱发生频次和干旱日数总体上呈北高(多)南低(少)分布特征。四季中夏旱频... 利用1961—2010年陕西省72个气象站逐日气温和降水资料,采用综合气象干旱指数法,统计分析了近50年陕西省气象干旱发生的时空分布特征。结果表明:陕西省年及四季干旱发生频次和干旱日数总体上呈北高(多)南低(少)分布特征。四季中夏旱频率最高,强度最强,春季其次。各等级干旱日数中轻旱日数最多,中、重和特旱日数依次减少。陕北北部长城沿线及关中中东部既是干旱高发区,也是干旱重发区;近50年陕西区域干旱强度和干旱日数均存在较明显的增加趋势,主要表现为春秋两个季节的变化,而夏季和冬季的变化趋势不明显;近50年陕西共发生32起持续性干旱事件,以春夏连旱为主;20世纪90年代中后期至2002年持续性干旱事件发生的频率高,强度强,反映出陕西区域极端干旱事件对全球气候变化有明显的响应。 展开更多
关键词 陕西省 综合气象干旱指数(ci) 变化特征
下载PDF
改进的综合气象干旱指数CI_(new)及其适用性分析 被引量:47
14
作者 王春林 郭晶 +1 位作者 薛丽芳 丁丽佳 《中国农业气象》 CSCD 2011年第4期621-626,631,共7页
针对综合气象干旱指数CI的"不合理旱情加剧"问题,采用线性递减权重方法计算近90d降水和可能蒸散,提出改进的综合气象干旱指数CInew,并从干旱过程描述能力、干旱频率及旱期相对少雨季节滞后特征方面,通过与CI相比较阐述CInew... 针对综合气象干旱指数CI的"不合理旱情加剧"问题,采用线性递减权重方法计算近90d降水和可能蒸散,提出改进的综合气象干旱指数CInew,并从干旱过程描述能力、干旱频率及旱期相对少雨季节滞后特征方面,通过与CI相比较阐述CInew的适用性特征。结果表明,(1)CInew在无降水时段平稳下降,有效克服了CI的"不合理旱情加剧"问题,能够描述干旱发生、发展和结束过程的丰富细节;(2)CInew的干旱频率与CI相比没有统计意义上的差异,但由于新的相对湿润度指数项MI90new统计时段由原来的30d延长至90d,使CInew能够刻画干旱频发开始月份(11月)相对于少雨时段开始月份(10月)的滞后效应。本文可为CInew在国内其它地方推广应用提供参考。 展开更多
关键词 改进的综合气象干旱指数cinew 综合气象干旱指数ci 动态监测
下载PDF
基于综合气象干旱指数(CI)的干旱时空动态格局分析——以甘肃省黄土高原区为例 被引量:25
15
作者 张调风 张勃 +3 位作者 王小敏 贾建英 尹海霞 何旭强 《生态环境学报》 CSCD 北大核心 2012年第1期13-20,共8页
借助ArcGIS 9.3和SPSS数据软件平台,根据甘肃省黄土高原区33个气象站1962-2010实测气象资料,利用综合气象干旱指数(CI)对甘肃省黄土高原区近50年的干旱特征进行了时空分析。首先计算了各站历年逐日的CI指数,统计近50年各站点出现的干旱... 借助ArcGIS 9.3和SPSS数据软件平台,根据甘肃省黄土高原区33个气象站1962-2010实测气象资料,利用综合气象干旱指数(CI)对甘肃省黄土高原区近50年的干旱特征进行了时空分析。首先计算了各站历年逐日的CI指数,统计近50年各站点出现的干旱过程、各时段的干旱事件,在此基础上分析了甘肃省黄土高原区历年各地区干旱发生的覆盖范围、频率和不同等级干旱发生的多年平均天数,揭示了甘肃省黄土高原区干旱发生的时空差异和动态格局。分析结果表明,(1)甘肃省黄土高原区有大范围干旱发生的年份,夏季和秋季较多分别有13、8 a,冬季最少,只有3 a。(2)从空间尺度来看,甘肃省黄土高原区中兰州-榆中-靖远一带和庆阳北部属于高值区,而岷县、渭源一带属于低值区;106°E以西"临洮-通渭-天水"一带和庆阳东南部是干旱变幅最大的地方。(3)从季节尺度来看,夏季干旱频率和持续日数最多,春季、秋季次之,冬季最少。 展开更多
关键词 气象干旱 综合气象干旱指数(ci) 时空格局 黄土高原
下载PDF
基于CI指数和K指数的近40a贵州安顺区域干旱演变特征 被引量:14
16
作者 吴哲红 詹沛刚 +2 位作者 陈贞宏 白慧 王劲松 《冰川冻土》 CSCD 北大核心 2013年第4期1044-1055,共12页
利用综合气象干旱指数(CI指数)和K干旱指数,对贵州安顺地区1971-2011年41a来气象干旱的时空分布状况、演变特征及突变情况进行了比较分析.结果表明:对严重的干旱时段,两种指数均能表现出来,对历年干旱过程及灾害的评定结果基本一致;CI... 利用综合气象干旱指数(CI指数)和K干旱指数,对贵州安顺地区1971-2011年41a来气象干旱的时空分布状况、演变特征及突变情况进行了比较分析.结果表明:对严重的干旱时段,两种指数均能表现出来,对历年干旱过程及灾害的评定结果基本一致;CI指数对干旱的评定更为精细,但K指数延续性更好;分季节的干旱分析中,两种指数对于夏季出现干旱概率较小的结论一致,对各季节平均干旱长度的评判基本一致.对时间演变的线性变化趋势以及M-K检验结果对比分析表明,春季和秋季干旱强度增强、夏季干旱强度减弱、年度平均干旱长度及春、秋季干旱长度增加的这几个趋势,两种方法两种指数结果一致,结论被认为是可信度较高的.M-K曲线检测表明:年度干旱长度在2008年后为增加的趋势,20世纪90年代以来春季干旱强度增强,20世纪末以来夏季干旱强度趋于减轻,秋季干旱强度增强,1970年代中期后春季干旱长度有增加的趋势,秋季干旱长度在20世纪80年代中期到90年代后增加的趋势可能发生了突变.年度干旱强度存在12~14a的长周期和年度干旱长度4~6a的短周期较为可信. 展开更多
关键词 ci指数 K指数 气象干旱 突变 周期
下载PDF
改进的CI指数在安徽省应用研究 被引量:17
17
作者 谢五三 田红 王胜 《气象》 CSCD 北大核心 2011年第11期1402-1408,共7页
运用安徽省77个气象台站1961—2009年的逐日气温和降水资料以及安徽省所有测墒站建站至2009年的土壤墒情资料,研究分析改进的CI指数在安徽省的应用情况。结果表明:在统计特征、与土壤墒情的相关性以及干旱的空间分布等方面,改进的CI指数... 运用安徽省77个气象台站1961—2009年的逐日气温和降水资料以及安徽省所有测墒站建站至2009年的土壤墒情资料,研究分析改进的CI指数在安徽省的应用情况。结果表明:在统计特征、与土壤墒情的相关性以及干旱的空间分布等方面,改进的CI指数NCC2CI保持了原来的CI指数OldCI的优点;但在干旱过程的逐日演变诊断方面,NCC2CI指数较OldCI指数有了诸多改进。对于安徽省干旱监测业务来说,NCC2CI明显优于OldCI。 展开更多
关键词 ci指数 气象干旱 对比分析 墒情
下载PDF
基于CI指数的宁夏干旱致灾因子特征指标分析 被引量:13
18
作者 李红英 张晓煜 +2 位作者 王静 郑广芬 王素艳 《高原气象》 CSCD 北大核心 2014年第4期995-1001,共7页
基于1981 2010年宁夏23个气象站逐日降水和气温资料,采用综合气象干旱指数CI,从干旱发生日数、干旱范围、干旱频率和干旱强度等方面对宁夏干旱致灾因子特征指标进行了分析,并作了致灾因子危险性评估与区划。结果表明,近30年宁夏干旱发... 基于1981 2010年宁夏23个气象站逐日降水和气温资料,采用综合气象干旱指数CI,从干旱发生日数、干旱范围、干旱频率和干旱强度等方面对宁夏干旱致灾因子特征指标进行了分析,并作了致灾因子危险性评估与区划。结果表明,近30年宁夏干旱发生日数、发生范围、干旱频率和干旱强度均呈增加趋势;干旱致灾因子危险性呈从南到北不断增加的趋势,致灾因子危险性指数最大为0.94,最小在0.1以下,南部大部分地区普遍处于干旱致灾因子低危险区,北部大部分地区处于干旱致灾因子高危险区。 展开更多
关键词 综合气象干旱指数ci 干旱致灾因子 宁夏
下载PDF
CI指数及SPEI指数在长江中下游地区的适用性分析 被引量:23
19
作者 王文 李亮 蔡晓军 《热带气象学报》 CSCD 北大核心 2015年第3期403-416,共14页
根据综合气象干旱指数(CI)在长江中下游地区应用中存在的不足,首先对CI中SPI指数等权累积降水进行合理的非等权处理及MI指数的优化,得到改进的综合气象干旱指数。然后利用1962—2013年长江中下游地区164个气象站的观测资料,对比分析了... 根据综合气象干旱指数(CI)在长江中下游地区应用中存在的不足,首先对CI中SPI指数等权累积降水进行合理的非等权处理及MI指数的优化,得到改进的综合气象干旱指数。然后利用1962—2013年长江中下游地区164个气象站的观测资料,对比分析了改进的综合气象干旱指数和标准化降水蒸散指数(SPEI)在长江中下游地区的适用性效果。结果表明:改进的综合气象干旱指数物理意义明确,解决了原CI指数对干旱开始时间、旱情发展中不连续加重现象和旱情解除时间滞后等不足,特别是对长江中下游地区的旱涝急转现象反映及时准确;设计的多时间尺度综合气象干旱指数与SPEI指数相关系数平均达0.8以上,说明得到的多时间尺度综合气象干旱指数对旱情的分析评估能力较强。经过适用性对比分析证明,月尺度综合气象干旱指数在江苏和安徽省应用效果要优于SPEI指数,湖南、江西和湖北省月尺度综合气象干旱指数在10—4月间的评估效果更好,SPEI指数在5—9月更优。因此,改进的综合气象干旱指数对长江中下游地区干旱分析与监测、预报预警等具有良好的推广应用价值。 展开更多
关键词 长江中下游地区 干旱 ci指数 SPEI指数 干旱监测 干旱指数改进
下载PDF
干旱指数CI的确定及其在新疆的应用 被引量:29
20
作者 江远安 赵逸舟 +1 位作者 陈颖 李元鹏 《沙漠与绿洲气象》 2010年第2期18-20,共3页
利用综合干旱指数CI,计算了新疆的干旱等级,并对CI指数定义的干旱等级在新疆的适用性作了分析。对北疆代表站的计算结果与实际情况的相关性达到了72.1%,南疆准确率为60.1%,可运用于对新疆的气候干旱监测业务。
关键词 干旱指数ci 干旱等级 适用性
下载PDF
上一页 1 2 76 下一页 到第
使用帮助 返回顶部