期刊文献+
共找到30篇文章
< 1 2 >
每页显示 20 50 100
Study on roughness coefficient for unsubmerged reed in the Changjiang Estuary 被引量:5
1
作者 GU Fengfeng MU Lin +3 位作者 QI Dingman LI Junhua KONG Lingshuang WAN Yuanyang 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2011年第5期108-113,共6页
The influence of density,foliage and stem flexibility on the roughness coefficients under unsubmerged conditions,such as Manning's n,is investigated experimentally.An instrumentation system has been developed for mea... The influence of density,foliage and stem flexibility on the roughness coefficients under unsubmerged conditions,such as Manning's n,is investigated experimentally.An instrumentation system has been developed for measuring the flow rate ranging from 0.1 to 0.3 L/s under the condition of different artificial foliated reeds.Based on the experimental results,the influence on the relationship between n with different density,foliage,flexibility and flow depth is discussed.It is found that the foliage and the density are the important factors affecting Manning's n.At a range of relatively low velocity and relatively large bending stiffness of stem,Manning's n is not influenced significanthy by the flexibility of stem. 展开更多
关键词 Manning's coefficient FOLIAGE DENsITY FLEXIBILITY REED
下载PDF
Reaearch on Skempton’s coefficient B based on the observation of groundwater of Changping station 被引量:6
2
作者 Yan Zhang Fuqiong Huang Guijuan Lai 《Earthquake Science》 CSCD 2009年第6期631-638,共8页
Based on isotropie linear poroelastic theory and under the undrained condition, we summarize three equations connecting the Skempton's coefficient B with the groundwater level. After analysis, we propose a method to ... Based on isotropie linear poroelastic theory and under the undrained condition, we summarize three equations connecting the Skempton's coefficient B with the groundwater level. After analysis, we propose a method to calculate the Skempton's coefficient B according to the relationship between water level and tidal strain. With this method we can get the value of B without the earthquake occurrence, which can provide the high frequency waves for research. Besides, we can also get the in-suit Skempton's coefficient B without the experiment of rock physics. In addition, we analyze the observed data of Changping station recorded in groundwater monitoring network (abv., GMN) before and after the Wenchuan Ms8.0 with this method, and find out there's a slight change of the value of B after the seismic waves passed by, which implies that the propagation of seismic waves may have brought some variations to the poroelastic medium of the well. 展开更多
关键词 skempton's coefficient B water level tidal strain atmospheric pressure volumetric strain
下载PDF
Hydraulic model with roughness coefficient updating method based on Kalman filter for channel flood forecast 被引量:4
3
作者 Hong-jun BAO Lin-na ZHAO 《Water Science and Engineering》 EI CAS 2011年第1期13-23,共11页
A real-time channel flood forecast model was developed to simulate channel flow in plain rivers based on the dynamic wave theory. Taking into consideration channel shape differences along the channel, a roughness upda... A real-time channel flood forecast model was developed to simulate channel flow in plain rivers based on the dynamic wave theory. Taking into consideration channel shape differences along the channel, a roughness updating technique was developed using the Kalman filter method to update Manning's roughness coefficient at each time step of the calculation processes. Channel shapes were simplified as rectangles, triangles, and parabolas, and the relationships between hydraulic radius and water depth were developed for plain rivers. Based on the relationship between the Froude number and the inertia terms of the momentum equation in the Saint-Venant equations, the relationship between Manning's roughness coefficient and water depth was obtained. Using the channel of the Huaihe River from Wangjiaba to Lutaizi stations as a case, to test the performance and rationality of the present flood routing model, the original hydraulic model was compared with the developed model. Results show that the stage hydrographs calculated by the developed flood routing model with the updated Manning's roughness coefficient have a good agreement with the observed stage hydrographs. This model performs better than the original hydraulic model. 展开更多
关键词 flood routing Manning's roughness coefficient updating method Kalman filter Froude number saint-Venant equations hydraulic model
下载PDF
The Prediction of Engel's Coefficient and Education Expenditure Based on the Linear Regression Model for Heilongjiang and Ontario
4
作者 Jinjin Yang 《Proceedings of Business and Economic Studies》 2020年第3期41-52,共12页
It is meaningful to study trends in food and education expenditure as proportions of total household expenditure.In this study,based on year 2006 to 2017 data from Heilongjiang province in China and Ontario province i... It is meaningful to study trends in food and education expenditure as proportions of total household expenditure.In this study,based on year 2006 to 2017 data from Heilongjiang province in China and Ontario province in Canada,a linear regression model is used to forecast the Engel’s coefficients(proportion spent on food)and the education proportion from year 2018 to 2027 for those two regions.The results suggest that in both regions the Engel’s coefficients show a decreasing trend,while the education expenditure proportions show an increasing trend.The ratios of education expenditure to food expenditure in both places show an increasing trend. 展开更多
关键词 Engel’s coefficient Education expenditure Linear regression Heilongjiang ONTARIO
下载PDF
Maluta's Coefficient of Musielak-Orlicz Sequence Spaces
5
作者 Hui Li YAO Ting Fu WANG 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2005年第4期699-704,共6页
In this paper, we give the formula of Maluta's coefficient for calculation, and don't add any conditions to the generating function Ф.
关键词 Maluta's coefficient Musielak-Orlicz sequence spaces
原文传递
MARDIA'S COEFFICIENT OF KURTOSIS IN ELLIPTICAL POPULATIONS
6
作者 MAIA BERKANE P.M.BENTLER 《Acta Mathematicae Applicatae Sinica》 SCIE CSCD 1990年第4期289-294,共6页
Mardia (1970) defined a measure of multivariate kurtosis and derived its asymptotic distributionfor samples from a multivariate normal population. Some new results on elliptical distributions areused to extend Mardia&... Mardia (1970) defined a measure of multivariate kurtosis and derived its asymptotic distributionfor samples from a multivariate normal population. Some new results on elliptical distributions areused to extend Mardia's results to samples from an elliptical distribution. These results provide amethod for testing hypotheses on the kurtosis parameter of elliptical distributions. An appendixprovides extensions of Kendall and Stuart's (1977) standard errors of bivariate moments to the thirdand fourth order. 展开更多
关键词 MARDIA’s coefficient OF KURTOsIs IN ELLIPTICAL POPULATIONs 云脚
原文传递
Study on Water Consumption Coefficient of People's Living and Its Regional Disparity in the North of China 被引量:1
7
作者 Wang Jing’ai 1-3, Mao Rui 3,4, Yang Mingchuan 3,4 & Zhou Junju 11 College of Geography & Remote Sensing 2 Key Laboratory of Regional Geography of Beijing Normal University +1 位作者 3 Key Laboratory of Environmental Change and Natural Disaster of Ministry of Education of China 4 College of Resources Science & Technology, Beijing Normal University, Beijing 100875, China 《Chinese Journal of Population,Resources and Environment》 北大核心 2005年第2期20-26,共7页
By employing the information-reshufflingmethod that integrates census data, precipitation dataand inquiry data of water consumption, this paperdiscusses 5 (water consumption coefficient of people’sliving) in allusion... By employing the information-reshufflingmethod that integrates census data, precipitation dataand inquiry data of water consumption, this paperdiscusses 5 (water consumption coefficient of people’sliving) in allusion to different precipitation zones anddifferent periods of time. The study shows that 5-(water consumption coefficient of urban people’sliving), 5. (water consumption coefficient of ruralpeople’s living) and increase with time passing, andthe increasing extent of 5 is 1.84, 2.62, 2.84 and 2.68times respectively from the west to the east, whichresults from the total quantity of water resources andthe speed of urbanization. 5- and 5. of eachprecipitation zone increased with 5- increasing morequickly than 5., and the difference between the twoalso increased when time passed. In the past fifty years(1950-2000), the increasing extent of 5- was 1.71,2.96, 2.41 and 2.33 times respectively from the westto the east, in which 200-400mm precipitation zoneincreased more than others. Meanwhile the increasingextent of 5. is 1.55, 1.60, 1.53 and 1.64 timesrespectively from the west to the east with eachprecipitation zone increasing similarly. The change of5-is due to the speed of urbanization and the stabilityof water resources. This study provides basis forcalculating the water demand of people’s living andrevealing the impact of water demand of people’s livingon ecological drought in different zones. 展开更多
关键词 The north of China precipitation zone water consumption coefficient of people’s living
下载PDF
Prediction of Henry's constant in polymer solutions using PCOR equation of state coupled with an activity coefficient model 被引量:2
8
作者 Somayeh Tourani Alireza Behvandi Farhad Khorasheh 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第3期528-535,共8页
In this paper,the polymer chain of rotator(PCOR) equation of state(EOS) was used together with an EOS/G^E mixing rule(MHV1) and the Wilson's equation as an excess-Gibbs-energy model in the proposed approach to ext... In this paper,the polymer chain of rotator(PCOR) equation of state(EOS) was used together with an EOS/G^E mixing rule(MHV1) and the Wilson's equation as an excess-Gibbs-energy model in the proposed approach to extend the capability and improve the accuracy of the PCOR EOS for predicting the Henry's constant of solutions containing polymers.The results of the proposed method compared with two equation of state(van der Waals and GC-Flory) and three activity coefficient models(UNIFAC,UNIFAC-FV and Entropic-FV) indicated that the PCOR EOS/Wilson's equation provided more accurate results.The interaction parameters of Wilson's equation were fitted with Henry's constant experimental data and the property parameters of PCOR,a and b,were fitted with experimental volume data(Tait equation).As a result,the present work provided a simple and useful model for prediction of Henry's constant for polymer solutions. 展开更多
关键词 Henry's constant Polymer solutions Equation of state Activity coefficient model
下载PDF
基于Logistic回归的古代玻璃制品化学成分分析和研究
9
作者 孙浩东 《电脑迷》 2023年第1期19-21,共3页
文章主要通过研究玻璃含有的不同化学成分,分析和鉴别古代的玻璃制品。首先分析了现有玻璃文物的数据,利用Spearman’s rank correlation coefficient和卡方检验表面分化、纹饰、颜色和玻璃类型之间的联系,采用Logistic回归鉴别未知文物... 文章主要通过研究玻璃含有的不同化学成分,分析和鉴别古代的玻璃制品。首先分析了现有玻璃文物的数据,利用Spearman’s rank correlation coefficient和卡方检验表面分化、纹饰、颜色和玻璃类型之间的联系,采用Logistic回归鉴别未知文物,分析其所属的类型,并分析了分类结果的灵敏度。通过分析可知,文章采用的分类方法,能较好地通过化学成分对玻璃进行分类。 展开更多
关键词 spearman’s rank correlation coefficient 卡方检验 LOGIsTIC回归
下载PDF
Vapor-Liquid Equilibrium Data of Carbon Dioxide+Methyl Propionate and Carbon Dioxide+Propyl Propionate Systems
10
作者 徐伟 谢传欣 +1 位作者 李洪玲 田宜灵 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2010年第3期317-324,I0002,共9页
High-pressure vapor-liquid equilibrium data for the binary systems of methyl propionate+carbon dioxide and propyl propionate+carbon dioxide were measured at pressure from 1.00 MPa to 12.00 MPa and temperature in the... High-pressure vapor-liquid equilibrium data for the binary systems of methyl propionate+carbon dioxide and propyl propionate+carbon dioxide were measured at pressure from 1.00 MPa to 12.00 MPa and temperature in the range from 313 K to 373 K. Experimental results were correlated with the Peng-Robinson equation of state with the two-parameter van der Waals mixing rule. At the same time, the Henry's coefficient, partial molar enthalpy change and partial molar entropy change of CO2 during dissolution at different temperature were also calculated. 展开更多
关键词 Carbon dioxide Methyl propionate Propyl propionate Vapor-liquid equilibrium data Henry's coefficient
下载PDF
Change Trend of Chinese Urban Residents' Food-nitrogen Consumption 被引量:2
11
作者 王俊能 许振成 彭晓春 《Agricultural Science & Technology》 CAS 2010年第4期176-179,共4页
Change trend of Chinese urban residents' per capita food-nitrogen annual consumption from 1981 to 2007 was analyzed and predicted by using ARIMA time-series model in order to reveal the change of urban food-nitrogen ... Change trend of Chinese urban residents' per capita food-nitrogen annual consumption from 1981 to 2007 was analyzed and predicted by using ARIMA time-series model in order to reveal the change of urban food-nitrogen consumption during the China's urbanization process.Results showed that after 1980s,the annual consumption of Chinese urban residents' food-nitrogen had a change trend of " increase-decrease-increase" and generally presented as a slight increasing trend;With the acceleration of rapid economic development and urbanization process,Chinese urban residents' food-nitrogen consumption will still keep a rising trend in future,and also has a large rising space. 展开更多
关键词 Food consumption NITROGEN spearman's rank correlation coefficient ARIMA model Urban residents China
下载PDF
Numerical modeling of flow in continuous bends from Daliushu to Shapotou in Yellow River 被引量:2
12
作者 He-fang JING Chun-guang LI +2 位作者 Ya-kun GUO Li-jun ZHU Yi-tian LI 《Water Science and Engineering》 EI CAS CSCD 2014年第2期194-207,共14页
The upper reach of the Yellow River from Daliushu to Shapotou consists of five bends and has complex topography. A two-dimensional Re-Normalisation Group (RNG) k-ε model was developed to simulate the flow in the re... The upper reach of the Yellow River from Daliushu to Shapotou consists of five bends and has complex topography. A two-dimensional Re-Normalisation Group (RNG) k-ε model was developed to simulate the flow in the reach. In order to take the circulation currents in the bends into account, the momentum equations were improved by adding an additional source term. Comparison of the numerical simulation with field measurements indicates that the improved two-dimensional depth-averaged RNG k-e model can improve the accuracy of the numerical simulation. A rapid adaptive algorithm was constructed, which can automatically adjust Manning's roughness coefficient in different parts of the study river reach. As a result, not only can the trial computation time be significantly shortened, but the accuracy of the numerical simulation can also be greatly improved. Comparison of the simulated and measured water surface slopes for four typical cases shows that the longitudinal and transverse slopes of the water surface increase with the average velocity upstream. In addition, comparison was made between the positions of the talweg and the main streamline, which coincide for most of the study river reach. However, deviations between the positions of the talweg and the main streamline were found at the junction of two bends, at the position where the river width suddenly decreases or increases. 展开更多
关键词 numerical simulation RNG k-e model Yellow River continuous bend circulationflow adaptive algorithm regarding Manning's roughness coefficient
下载PDF
Study of Bed Friction Factor for the Wu River Estuary
13
作者 Chin-Wu LAN Cyuan-Chen LEE 《China Ocean Engineering》 SCIE EI 2006年第4期557-572,共16页
In this research the bed friction effect is estimated of a river estuary by use of hydrodynamic analysis. The on-site sampled data of the Wu River estuary is applied to the analysis. There are many dynamic factors tha... In this research the bed friction effect is estimated of a river estuary by use of hydrodynamic analysis. The on-site sampled data of the Wu River estuary is applied to the analysis. There are many dynamic factors that affect the flow characteristics in the estuary. The effect of tide on the generation of tidal current, bottom friction and geometry effect is the focus of this paper. The Wu River estuary is about 15 hn in length, with a small bottom slope and no physical obstruction; thus the incident wave at the estuary is considered a progressive wave with damping effect. The amplitude reduction and phase shift of the incident wave are analyzed. By the analysis of celerity reduction factor of the estuary, the estimated value of mean resistance coefficient M(μ ,κ), damping modulus μ, and wave number κ for the sections at observation stations can be determined. Furthermore, data gathered from on-site observations are applied for validation. Finally, Manning' s coefficient for each section of the observation stations can be determined. It is found that the value of Manning' s coefficient is small downstream and increases towards upstream, and that the bed friction effect of an estuary varies largely. The estimated results of the paper are compared with the empirical formulas and the modified solution for practical application is discussed. 展开更多
关键词 EsTUARY Manning' s coefficient celerity reduction factor damping modulus resistance coefficient
下载PDF
Study on Optical Activities of A3BGa3Si2O14 Crystals
14
作者 Wei Aijian Wang Baolin Yuan Duorong 《Journal of Rare Earths》 SCIE EI CAS CSCD 2006年第4期391-391,共1页
Four crystals with the general formula of A3BGa3Si2O14 (A = Ca^2+, Sr^2+; B=Nb^5+ , Ta^5+) grown by using the Czoehralsky technique were reported. They are all uniaxial and belong to 32 point group. Their transm... Four crystals with the general formula of A3BGa3Si2O14 (A = Ca^2+, Sr^2+; B=Nb^5+ , Ta^5+) grown by using the Czoehralsky technique were reported. They are all uniaxial and belong to 32 point group. Their transmission, rotatory angle and specific rotation dispersion were investigated by speetrophotometer and compared with LGS. The transmission spectra show that they are transparent in the visible wavelength region beyond 294 nm and infrared region, and their transmission are all larger than that of LGS.The transmission spectra between parallel polasizers show that they have large optical activities which are larger than that of LGS. Of the four crystals, Sr3NbGa3Si2O14 has the largest optical activity : 240.75 (°)·mm^-1 at 0.30 μm wavelength, 34.73 (°) ·mm^-1 at 0. 633 μm wavelength. The Bohzmann's coefficients of these crystals were calculated, which were in good agreement with earlier measurement in other reference. 展开更多
关键词 inorganic non-metallic materials crystal growth A3BGa3si2O14 crystal optical activity boltzmann's coefficients rare earths
下载PDF
Econometric Investigation of DSE's Portfolios through Selective Micro and Macro Economic Indicators
15
作者 Ahammad Hossain Md. Kamruzzaman Md. Ayub Ali 《Journal of Statistical Science and Application》 2016年第3期144-153,共10页
This paper examines the impact of the portfolios of Dhaka Stock Exchange (DSE) with corresponding to the selective macro and micro economic indicators of Bangladesh. The microeconomic indicators are Invested Market ... This paper examines the impact of the portfolios of Dhaka Stock Exchange (DSE) with corresponding to the selective macro and micro economic indicators of Bangladesh. The microeconomic indicators are Invested Market Capital (1MC) (US$) and the number of Total Enlisted Company (TEC) which have direct and immediate impact on the Stock Turnover Ratio (STR) of DSE and the macroeconomic indicators are Gross Domestic Product (GDP), Gross National Income (GNI), Gross Saving (GS), Gross Inflation (GI), Deposit Interest Rate (DIR), and Gross Foreign Investment (GFI) which have indirect and long run impact on DSE portfolios. To investigate the direct impact on DSE's turnover ratio, the Cobb-Douglas production function is applied and to investigate the indirect and long run impact, multiple linear regression models are also applied. The estimated results are diagnosed using magnitudes of derivatives, gradient and Wald's coefficient restriction with respect to the macro and micro economic indicators. 展开更多
关键词 Direct and immediate impact Indirect and long run impact magnitudes of derivatives gradient andWald's coefficient restriction
下载PDF
Study on collocations in English writing by Chinese students 被引量:1
16
作者 SHEN Ying 《Sino-US English Teaching》 2009年第3期25-30,共6页
This study attempted to identify the characteristics of collocations and determine the existence of a relationship between collocations and coherence in writing by Chinese students. This study produced the following r... This study attempted to identify the characteristics of collocations and determine the existence of a relationship between collocations and coherence in writing by Chinese students. This study produced the following results: (1) Common mistaken collocations are seen in the writings by Chinese non-English and English majors; specifically, both English majors and non-English majors made more lexical collocational mistakes than grammatical collocational mistakes in terms of the total number of mistakes and in the type of mistaken collocations; (2) No evident relationship between the correct usage of collocations and coherence is found in the writings of non-English majors as compared to that of English majors. Thus, we can conclude that with the development of skills with the English language, the relationship between the correct use of collocations and coherence becomes increasingly stronger. 展开更多
关键词 COLLOCATIONs COHEsION CORRELATION person's correlation coefficient
下载PDF
Characteristics of Ambient Air Quality in the Central Urban Area of Western Guizhou in the Past Five Years 被引量:1
17
作者 Shihua JIANG Zaixiang CHI +3 位作者 Kai XU Lijuan LIU Zijiang YANG Changwen CHEN 《Meteorological and Environmental Research》 CAS 2020年第6期23-30,共8页
Air is an important condition for human activities and survival,and its quality is closely related to the quality of life and level of health for the people.In recent years,the problem caused by air quality has become... Air is an important condition for human activities and survival,and its quality is closely related to the quality of life and level of health for the people.In recent years,the problem caused by air quality has become one of the main problems that endanger human health and restrict economic development,which has been widely concerned.In this paper,the air quality status and its changing trend were analyzed by using the methods of the comprehensive index of ambient air quality and Spearman s rank correlation coefficient,based on the hourly pollutant concentration data of five national ambient air quality monitoring stations in the central urban area of Liupanshui City,Guizhou Province from January 1,2015 to December 31,2019.The results showed that the concentration of air pollutants in the atmosphere in the past five years showed a downward trend in the central urban area of Liupanshui City.During 2018-2019,the air quality has been up to the standard for two consecutive years,and it was developing to a higher quality direction.The air quality was better in summer half year than in winter half year.In one year,the air quality was the best in June and the worst in February.The air quality was the best at 07:00 and the worst at 21:00 every day.The air quality in the east and the west of the city was better than that in the middle.In most years,the activities,making and burning paper to resemble money as an offering sacrifices to gods or ancestors in Zhongyuan Festival,caused serious pollution. 展开更多
关键词 Air quality Pollution concentration spearman s rank correlation coefficient Change trends
下载PDF
ILipo-PseAAC: Identification of Lipoylation Sites Using Statistical Moments and General PseAAC
18
作者 Talha Imtiaz Baig Yaser Daanial Khan +3 位作者 Talha Mahboob Alam Bharat Biswal Hanan Aljuaid Durdana Qaiser Gillani 《Computers, Materials & Continua》 SCIE EI 2022年第4期215-230,共16页
Lysine Lipoylation is a protective and conserved Post Translational Modification(PTM)in proteomics research like prokaryotes and eukaryotes.It is connected with many biological processes and closely linked with many m... Lysine Lipoylation is a protective and conserved Post Translational Modification(PTM)in proteomics research like prokaryotes and eukaryotes.It is connected with many biological processes and closely linked with many metabolic diseases.To develop a perfect and accurate classification model for identifying lipoylation sites at the protein level,the computational methods and several other factors play a key role in this purpose.Usually,most of the techniques and different traditional experimental models have a very high cost.They are time-consuming;so,it is required to construct a predictor model to extract lysine lipoylation sites.This study proposes a model that could predict lysine lipoylation sites with the help of a classification method known as Artificial Neural Network(ANN).The ANN algorithm deals with the noise problem and imbalance classification in lipoylation sites dataset samples.As the result shows in ten-fold cross-validation,a brilliant performance is achieved through the predictor model with an accuracy of 99.88%,and also achieved 0.9976 as the highest value of MCC.So,the predictor model is a very useful and helpful tool for lipoylation sites prediction.Some of the residues around lysine lipoylation sites play a vital part in prediction,as demonstrated during feature analysis.The wonderful results reported through the evaluation and prediction of this model can provide an informative and relative explanation for lipoylation and its molecular mechanisms. 展开更多
关键词 Lipoylation lysine feature vector post translational modification amino acid Mathew’s correlation coefficient neural network
下载PDF
An Automatic Monitoring and Alarming Method for the Power Supply of Weather Radars
19
作者 Shihua JIANG Ruyong LONG +3 位作者 Changwen CHEN Lijuan LIU Kun ZHAO Liang HOU 《Meteorological and Environmental Research》 CAS 2021年第2期23-25,29,共4页
As weather radar stations require headroom environment to operate,they were mostly built on highlands which are usually unattended.The mains supply is relatively poor,and the risk of radar stoppages due to power outag... As weather radar stations require headroom environment to operate,they were mostly built on highlands which are usually unattended.The mains supply is relatively poor,and the risk of radar stoppages due to power outage is therefore ever-present.As such,the radar construction program is used to build a complementary security video monitoring system.By collecting monitoring images of the regulated power supply in real-time from power supply auto transfer systems in distribution rooms and radar transceiver rooms,using Spearman’s rank correlation coefficient to analyse pixel variation trends,and supplementing statistical analysis of pixel characteristics difference to eliminate misjudgments resulting from low image contrast in special scenarios,a software can be developed through C#.It has the function of automatically monitoring mains supply and alerting staff on duty to handle the power outage in a timely manner via text message so that any potential risk is neutralised before it can cause damage.This monitoring and auto-alerting approach is generally applicable to unattended rooms with large amounts of electronical equipment. 展开更多
关键词 Weather radar spearman’s rank correlation coefficient Power supply MONITOR ALARM
下载PDF
Temporary Crops in the Brazilian Agricultural Frontier
20
作者 Rogério Edivaldo Freitas 《Agricultural Sciences》 2022年第2期244-267,共24页
Food production remains one of the main challenges for humankind in this century, and Brazil is one of the largest food-producing countries that have yet some land for economically or technically profitable farming ex... Food production remains one of the main challenges for humankind in this century, and Brazil is one of the largest food-producing countries that have yet some land for economically or technically profitable farming expansion. Moreover, knowing which areas constitute the Brazilian agricultural frontier is crucial for improving public policies and logistics infrastructure decisions. Data from the Brazilian Institute of Geography and Statistics from 1995 to 2019 were used in this study. We aimed to map and measure the expansion of agricultural areas in Brazil from 1995 to 2019 for temporary crops according to their mesoregions. We used a four-stage methodology, compared the results of two agglomerative clustering methods, and identified similar mesoregions based on their share trends in the Brazilian agricultural seeded area. Some mesoregions had higher positive trend values for their share of the Brazilian agricultural seeded area: Mato-grossense North (MT), Mato-grossense Northeast (MT), Mato Grosso do Sul Southwest (MS), Goiano South (GO), Extreme West Bahia (BA), Maranhense South (MA), Piauiense Southwest (PI), and Tocantins Eastern (TO). As a second leading group, the Paranaíba Upstream (MG), S&#227;o José do Rio Preto (SP), Mato-grossense Southeast (MT), and Goiano East (GO), must be emphasized. Further research is recommended, including extending the study to permanent crops and applying top-down analysis targeting microregions or municipalities in the identified mesoregions. 展开更多
关键词 Agricultural Frontier Brazil Mesoregions spearman’s Correlation coefficient CLUsTERING
下载PDF
上一页 1 2 下一页 到第
使用帮助 返回顶部