Satellite images are considered reliable data that preserve land cover information. In the field of remote sensing, these images allow relevant analyses of changes in space over time through the use of computer tools....Satellite images are considered reliable data that preserve land cover information. In the field of remote sensing, these images allow relevant analyses of changes in space over time through the use of computer tools. In this study, we have applied the “discriminant” change detection algorithm. In this, we have verified its effectiveness in multi-temporal studies. Also, we have determined the change in forest dynamics in the Ikongo district of Madagascar between 2000 and 2015. During the treatments, we have used the Landsat TM satellite images for the years 2000, 2005 and 2010 as well as ETM+ for 2015. Thus, analyses carried out have allowed us to note that between 2000-2005, 1.4% of natural forest disappeared. And, between 2005-2010, forests degradation<span><span><span style="font-family:;" "=""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">was 1.8%. Also, between 2010-2015, about 0.5% of the natural forest conserved in 2010 disappeared. Furthermore, we have found that the discriminant algorithm is considerably efficient in terms of monitoring the dynamics of forest cover change.</span></span></span>展开更多
In the wake of climate warming, the water level of Lake Qinghai has been continuously and rapidly declining during the past decades, causing the regional government and citizens to worry about its future as a water re...In the wake of climate warming, the water level of Lake Qinghai has been continuously and rapidly declining during the past decades, causing the regional government and citizens to worry about its future as a water resource. To understand the lake evolution process, the hydro-chemical characteristics of Lake Qinghai were investigated in August of 2008. The results show that Na<sup>+</sup> and Cl<sup>-</sup> are the dominant cations and anions in the lake water, respectively, and hydrochemistry type is Cl<sup>-</sup>- Na<sup>+</sup> with an obvious characteristic of a saline lake. The Gibbs plot illuminates that evaporation/crystallization is responsible for the chemical composition of the lake water. The variation in hydro-chemical regime might be attributed to the reduced lake levels between 1960s and 2000s. The lake level significantly correlated with the precipitation and evaporation in the Lake Qinghai catchment. In addition, changes of the lake level in the future are simulated according to climate warming scenarios from the IPCC report. The simulated results suggest that the lake level could rise again in the following decades due to the increased precipitation under the climate warming conditions, which is already a trend in the lake level observation data.展开更多
The present study attempts to determine diurnal changes by testing the differential sensitivity and temporal resolution in morning-type,evening-type,and intermediate-type individuals with normal hearing.Thirty partici...The present study attempts to determine diurnal changes by testing the differential sensitivity and temporal resolution in morning-type,evening-type,and intermediate-type individuals with normal hearing.Thirty participants with normal hearing were divided into morningtype,evening-type,and intermediate-type using“MorningnesseEveningness Questionnaire”.The tests of differential sensitivity and temporal resolution were administered to all the participants in the morning and evening,respectively.The differences in the test results between different timing across all the three groups were analyzed.The results of the study showed that there was a significant diurnal effect on psychoacoustic tests as morning-type individuals performed better when tested in morning and evening-type performed better when they were tested in evening.However,there was no diurnal effect found in intermediate group.The lack of inhibitory control and poor cognitive load in off peak time could have lead to poor scores.Thus,the variable of diurnal effects should be considered in further studies on psychoacoustic tests,especially in young adults.Furthermore,studies could be performed to explore diurnal effects on objective audiological tests in a larger group of population in the future.展开更多
Landuse and land cover change is regarded as a good indicator that represents the impact of human activities on earth’s environment.When the large collection of multi-temporal satellite images has become available,it...Landuse and land cover change is regarded as a good indicator that represents the impact of human activities on earth’s environment.When the large collection of multi-temporal satellite images has become available,it is possible to study a long-term historical process of land cover change.This study aims to investigate the spatio-temporal pattern and driving force of land cover change in the Pearl River Delta region in southern China,where the rapid development has been witnessed since 1980s.The fast economic growth has been associated with an accelerated expansion of urban landuse,which has been recorded by historical remote sensing images.This paper reports the method and outcome of the research that attempts to model spatio-temporal pattern of land cover change using multi-temporal satellite images.The classified satellite images were compared to detect the change from various landuse types to built-up areas.The trajectories of land cover change have then been established based on the time-series of the classified land cover classes.The correlation between the expansion of built-up areas and selected economic data has also been analysed for better understanding on the driving force of the rapid urbanisation process.The result shows that,since early 1990s,the dominant trend of land cover change has been from farmland to urban landuse.The relationship between economic growth indicator(measured by GDP)and built-up area can well fit into a linear regression model with correlation coefficients greater than 0.9.It is quite clear that cities or towns have been sprawling in general,demonstrating two growth models that were closely related to the economic development stages.展开更多
土地利用变更模型及其事务处理机制是土地利用现状管理信息系统的核心.传统变更模型所支持的变更操作粒度较为单一、事务完整性差、时空语义表现过于单薄.在分析了土地利用变更特点和存在问题的基础上,提出了一种土地利用多级变更模型LU...土地利用变更模型及其事务处理机制是土地利用现状管理信息系统的核心.传统变更模型所支持的变更操作粒度较为单一、事务完整性差、时空语义表现过于单薄.在分析了土地利用变更特点和存在问题的基础上,提出了一种土地利用多级变更模型LU-MCM(land use multi-level change model),模型以土地利用变迁过程为变更对象,并进一步将之划分为多级变更逻辑单元进行组合描述,而所需解决的长事务处理机制则通过扩展的多粒度树状事务模型实现.土地利用现状管理信息系统的设计和实现证明,该模型对土地利用变迁过程表达效果较好,为土地利用变更数据管理提供了思路.展开更多
文摘Satellite images are considered reliable data that preserve land cover information. In the field of remote sensing, these images allow relevant analyses of changes in space over time through the use of computer tools. In this study, we have applied the “discriminant” change detection algorithm. In this, we have verified its effectiveness in multi-temporal studies. Also, we have determined the change in forest dynamics in the Ikongo district of Madagascar between 2000 and 2015. During the treatments, we have used the Landsat TM satellite images for the years 2000, 2005 and 2010 as well as ETM+ for 2015. Thus, analyses carried out have allowed us to note that between 2000-2005, 1.4% of natural forest disappeared. And, between 2005-2010, forests degradation<span><span><span style="font-family:;" "=""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">was 1.8%. Also, between 2010-2015, about 0.5% of the natural forest conserved in 2010 disappeared. Furthermore, we have found that the discriminant algorithm is considerably efficient in terms of monitoring the dynamics of forest cover change.</span></span></span>
文摘In the wake of climate warming, the water level of Lake Qinghai has been continuously and rapidly declining during the past decades, causing the regional government and citizens to worry about its future as a water resource. To understand the lake evolution process, the hydro-chemical characteristics of Lake Qinghai were investigated in August of 2008. The results show that Na<sup>+</sup> and Cl<sup>-</sup> are the dominant cations and anions in the lake water, respectively, and hydrochemistry type is Cl<sup>-</sup>- Na<sup>+</sup> with an obvious characteristic of a saline lake. The Gibbs plot illuminates that evaporation/crystallization is responsible for the chemical composition of the lake water. The variation in hydro-chemical regime might be attributed to the reduced lake levels between 1960s and 2000s. The lake level significantly correlated with the precipitation and evaporation in the Lake Qinghai catchment. In addition, changes of the lake level in the future are simulated according to climate warming scenarios from the IPCC report. The simulated results suggest that the lake level could rise again in the following decades due to the increased precipitation under the climate warming conditions, which is already a trend in the lake level observation data.
文摘The present study attempts to determine diurnal changes by testing the differential sensitivity and temporal resolution in morning-type,evening-type,and intermediate-type individuals with normal hearing.Thirty participants with normal hearing were divided into morningtype,evening-type,and intermediate-type using“MorningnesseEveningness Questionnaire”.The tests of differential sensitivity and temporal resolution were administered to all the participants in the morning and evening,respectively.The differences in the test results between different timing across all the three groups were analyzed.The results of the study showed that there was a significant diurnal effect on psychoacoustic tests as morning-type individuals performed better when tested in morning and evening-type performed better when they were tested in evening.However,there was no diurnal effect found in intermediate group.The lack of inhibitory control and poor cognitive load in off peak time could have lead to poor scores.Thus,the variable of diurnal effects should be considered in further studies on psychoacoustic tests,especially in young adults.Furthermore,studies could be performed to explore diurnal effects on objective audiological tests in a larger group of population in the future.
基金supported by the National Basic Research Program of China("973"Project)(Grant No.2006CB701304)Research Grants Council General Research Fund of Hong Kong(Grant No.HKBU2029/07P)Hong Kong Baptist University Faculty Research Grant(Grant No.FRG/06-07/II-76)
文摘Landuse and land cover change is regarded as a good indicator that represents the impact of human activities on earth’s environment.When the large collection of multi-temporal satellite images has become available,it is possible to study a long-term historical process of land cover change.This study aims to investigate the spatio-temporal pattern and driving force of land cover change in the Pearl River Delta region in southern China,where the rapid development has been witnessed since 1980s.The fast economic growth has been associated with an accelerated expansion of urban landuse,which has been recorded by historical remote sensing images.This paper reports the method and outcome of the research that attempts to model spatio-temporal pattern of land cover change using multi-temporal satellite images.The classified satellite images were compared to detect the change from various landuse types to built-up areas.The trajectories of land cover change have then been established based on the time-series of the classified land cover classes.The correlation between the expansion of built-up areas and selected economic data has also been analysed for better understanding on the driving force of the rapid urbanisation process.The result shows that,since early 1990s,the dominant trend of land cover change has been from farmland to urban landuse.The relationship between economic growth indicator(measured by GDP)and built-up area can well fit into a linear regression model with correlation coefficients greater than 0.9.It is quite clear that cities or towns have been sprawling in general,demonstrating two growth models that were closely related to the economic development stages.
文摘土地利用变更模型及其事务处理机制是土地利用现状管理信息系统的核心.传统变更模型所支持的变更操作粒度较为单一、事务完整性差、时空语义表现过于单薄.在分析了土地利用变更特点和存在问题的基础上,提出了一种土地利用多级变更模型LU-MCM(land use multi-level change model),模型以土地利用变迁过程为变更对象,并进一步将之划分为多级变更逻辑单元进行组合描述,而所需解决的长事务处理机制则通过扩展的多粒度树状事务模型实现.土地利用现状管理信息系统的设计和实现证明,该模型对土地利用变迁过程表达效果较好,为土地利用变更数据管理提供了思路.
