Landscape pattern is a widely used concept for the demonstration of landscape characteristic features. The integral spatial distribution trend of landscape elements is interested point in the landscape ecological rese...Landscape pattern is a widely used concept for the demonstration of landscape characteristic features. The integral spatial distribution trend of landscape elements is interested point in the landscape ecological research, especially in those of complex secondary forest regions with confusing mosaics of land cover. Trend surface analysis which used in community and population ecological researches was introduced to reveal the landscape pattern. A reasonable and reliable approach for application of trend surface analysis was provided in detail. As key steps of the approach, uniform grid point sampling method was developed. The efforts were also concentrated at an example of Guandishan forested landscape. Some basic rules of spatial distribution of landscape elements were exclaimed. These will be benefit to the further study in the area to enhance the forest sustainable management and landscape planning.展开更多
In this paper, first, based on landscape ecology theories, we respectively selected indexes from 4 aspects, area, edge, shape, and density, of the landscape type to describe the status of forest landscape patterns, an...In this paper, first, based on landscape ecology theories, we respectively selected indexes from 4 aspects, area, edge, shape, and density, of the landscape type to describe the status of forest landscape patterns, and we established the stability index of landscape pattern (LSBI). Then, based on geo-statistical theories, we divided the forest in the reservoir area into 3990 grids of 4 km × 4 km using network technology and employing ordinary Kriging modelling to make trend surface analyses of the forest resources in the reservoir area. Finally, based on statistics principles, we used sampling theory to systematically extract 227 samples to obtain 7 periods of remote-sensing data from 1990a to 2012a. Then, we classified and extracted the forest in the sampling area using remote sensing, and we analysed each result with an Autoregressive Integrated Moving Average Model (ARIMA) time-series model. The results indicated the following: 1) the landscape structure of the reservoir area was primarily needle-leaved forest, broad-leaved forest and bush forest, and the mixed stands and bamboo stands were secondary;2) the difference of the forest landscape pattern stability in the reservoir area, in all directions, was not significant, but the southern region was slightly more stable;and 3) the stability of the forest landscape pattern in the reservoir area increased from 1990a to 2012a. It kept increasing until 2016a. This study provides a theoretical basis for the reasonable management and decisions about the forest resources in the Three Gorges Reservoir Area. Meanwhile, it also explores methods for relevant research and has practical significance.展开更多
Background: Salivary gland tumours (SGTs) are rare, but recent reports suggest an increasing incidence. Although there are previous Nigerian studies on the patterns of SGTs, patterns and trends of disease may change o...Background: Salivary gland tumours (SGTs) are rare, but recent reports suggest an increasing incidence. Although there are previous Nigerian studies on the patterns of SGTs, patterns and trends of disease may change over time. The aim of this study was to describe the pattern of presentation of SGTs, and to determine the trends in occurrence of SGTs at Federal Teaching Hospital (FTH), Gombe over a period of 15 years. Method: This descriptive study included cases of histologically diagnosed SGTs from January 2008 to December 2022. Relevant information (age, gender, site, year of diagnosis, and histopathologic diagnosis) was extracted from the cancer registers and histopathologic records. The lesions were then categorized into benign and malignant SGTs and grouped into three groups spanning 5 years each based on the year of diagnosis. Data analysis was done using IBM SPSS version 23, and p ≤ 0.05 was considered statistically significant. Results: There were 93 (61.2%) benign and 59 (38.8%) malignant SGTs. Benign SGTs had a mean age of 36.4 ± 13.6 years, and were more common in females (57.0%), and in the parotid (41.9%). Pleomorphic adenoma (94.6%) was the most common benign SGT. Malignant SGTs had a mean age of 44.5 ± 18.4 years, with male predilection (54.2%) and occurrence mostly in the palate (27.6%) and parotid (22.4%). Mucoepidermoid carcinoma (39.0%) and adenoid cystic carcinoma (32.2%) were the most frequent malignant SGTs. The mean age of occurrence of malignant SGTs was significantly higher than that of benign SGTs (p = 0.005). The trend analysis showed that there has been a steady rise in the proportion of males presenting with malignant SGTs. Similarly, there has been a steady increase in the frequency of benign SGTs in the parotid. The palate was the predominant site for the malignant SGTs between 2008 and 2012, but in the last five years (2018 to 2022), the parotid has become the predominant site. Over the duration of the study, the ratio of benign to malignant SGTs has remained relatively constant. Conclusion: While the overall pattern of presentation of SGTs in Gombe is similar to reports in the literature, this study has identified some changes in trends over the years.展开更多
The identification of control chart patterns is very important in statistical process control. Control chart patterns are categorized as natural and unnatural. The presence of unnatural patterns means that a process i...The identification of control chart patterns is very important in statistical process control. Control chart patterns are categorized as natural and unnatural. The presence of unnatural patterns means that a process is out of statistical control and there are assignable causes for process variation that should be investigated. This paper proposes an artificial neural network algorithm to identify the three basic control chart patterns;natural, shift, and trend. This identification is in addition to the traditional statistical detection of runs in data, since runs are one of the out of control situations. It is assumed that a process starts as a natural pattern and then may undergo only one out of control pattern at a time. The performance of the proposed algorithm was evaluated by measuring the probability of success in identifying the three basic patterns accurately, and comparing these results with previous research work. The comparison showed that the proposed algorithm realized better identification than others.展开更多
Shigellosis causes diarrheal disease in humans in both developed and developing countries, and multi-drug resistance in Shigella is an emerging problem. Understanding changing resistance patterns is important in deter...Shigellosis causes diarrheal disease in humans in both developed and developing countries, and multi-drug resistance in Shigella is an emerging problem. Understanding changing resistance patterns is important in determining appropriate antibiotic treatments. This meta-analysis systematically evaluated aminoglycoside resistance in Shigella. A systematic review was constructed based on MEDLINE and EMBASE databases. Randomeffect models or fixed-effect models were used based on P value considering the possibility of heterogeneity between studies for meta-analysis. Data manipulation and statistical analyses were performed using software STATA 11.0. By means of meta-analysis, we found a lower resistance to three kinds of aminoglycosides in the Europe-America areas during the 12 year study period than that of the Asia-Africa areas. Kanamycin resistance was observed to be the most common drug resistance among Shigella isolates with a prevalence of 6.88% （95%CI： 6.36%-7.43%）. Comparison of data from Europe-America and Asia-Africa areas revealed that Shigella flexneri resistance was greater than the resistance calculated for Shigella sonnei. Importantly, Shigella sonnei has played a significant role in aminoglycoside-resistance in recent years. Similarly, data showed that resistance to these drugs in children was higher than the corresponding data of adults. In conclusion, aminoglycoside-resistant Shigella is not an unusual phenomenon worldwide. Distribution in Shigella resistance differs sharply based on geographic areas, periods of time and subtypes. The results from the present study highlight the need for con- tinuous surveillance of resistance and control of antibiotic usage.展开更多
Based on observed daily precipitation data of 540 stations and 3,839 gridded data from the high-resolution regional climate model COSMO-Climate Limited-area Modeling(CCLM)for 1961–2000,the simulation ability of CCLM ...Based on observed daily precipitation data of 540 stations and 3,839 gridded data from the high-resolution regional climate model COSMO-Climate Limited-area Modeling(CCLM)for 1961–2000,the simulation ability of CCLM on daily precipitation in China is examined,and the variation of daily precipitation distribution pattern is revealed.By applying the probability distribution and extreme value theory to the projected daily precipitation(2011–2050)under SRES A1B scenario with CCLM,trends of daily precipitation series and daily precipitation extremes are analyzed.Results show that except for the western Qinghai-Tibetan Plateau and South China,distribution patterns of the kurtosis and skewness calculated from the simulated and observed series are consistent with each other;their spatial correlation coefcients are above 0.75.The CCLM can well capture the distribution characteristics of daily precipitation over China.It is projected that in some parts of the Jianghuai region,central-eastern Northeast China and Inner Mongolia,the kurtosis and skewness will increase significantly,and precipitation extremes will increase during 2011–2050.The projected increase of maximum daily rainfall and longest non-precipitation period during flood season in the aforementioned regions,also show increasing trends of droughts and floods in the next 40 years.展开更多
Migration plays an increasing role in China＇s economy since mobility rose and economic restructuring has proceeded during the last three decades. Given the background of most studies focusing on migration in a partic...Migration plays an increasing role in China＇s economy since mobility rose and economic restructuring has proceeded during the last three decades. Given the background of most studies focusing on migration in a particular period, there is a critical need to analyze the spatial-temporal patterns of migration. Using bicomponent trend mapping technique and interprovincial migration data during the periods 1985-1990, 1990-1995, 1995-2000, 2000- 2005, and 2005-2010 we analyze net-, in-, out-migration intensity, and their changes over time in this study. Strong spatial variations in migration intensity were found in China＇s interprovincial migration, and substantial increase in migration intensity was also detected in eastern China during 1985-2010. Eight key destinations are mostly located within the three rapidly growing economic zones of eastern China （Pearl River Delta, Yangtze River Delta and Beijing-Tianjin-Hebei Metropolitan Region）, and they are classified into three types： mature, emerging, and fluctuant origins, while most key origins are relatively undeveloped central and western provinces, which are exactly in accordance with China＇s economic development patterns. The results of bicomponent trend mapping indicate that, in a sense, the migration in the south was more active than the north over the last three decades. The result shows the new changing features of spatial-temporal patterns of China＇s interprovincial migration that Fan and Chen did not find out in their research. A series of social-economic changes including rural transformation, balanced regional development, and labor market changes should be paid more attention to explore China＇s future interprovincial migration.展开更多
This study analyzed the spatial distribution and temporal trends of precipitation and its extremes over Nigeria from 1979-2013 using climate indices, in order to assess climatic extremes in the country. Daily precipit...This study analyzed the spatial distribution and temporal trends of precipitation and its extremes over Nigeria from 1979-2013 using climate indices, in order to assess climatic extremes in the country. Daily precipitation data used in this study were obtained from Nigeria Meteorological Agency (NIMET), Lagos. The study used climate indices developed by the Expert Team on Climate Change Detection (ETCCDI) for assessing extreme precipitation. Sen’s slope estimator and Mann-Kendall trend test were employed in data analysis. Results revealed that precipitation and its extremes varied spatially across Nigeria. Significant negative trends were observed in most of the precipitation indices for the period under study. Furthermore, significant downward trends were observed in the CWD (Consecutive Wet Day) while the CDD (Consecutive Dry Day) showed significant upward trends in all the regions. These spatial and temporal changes indicate that Nigeria’s climate is trending towards a warmer and drier condition, which could be attributed to global warming-induced climate change;which altered historical rainfall patterns thereby leading to extreme events. The findings of this study have provided useful information in understanding the extreme events that are assumed by the general populace to be normal recurrent events in Nigeria. The results of the analysis of yearly and decadal changes in precipitation totals and extreme values for the last 35 years (1979-2013) suggest the likelihood of severe impacts on water resources, agriculture, and water-sensitive economic activities展开更多
[Objective] The aim was to study the characteristics of the spatial structural patterns and temporal variability of annual precipitation in Ningxia.[Method] Using rotated empirical orthogonal function,the precipitatio...[Objective] The aim was to study the characteristics of the spatial structural patterns and temporal variability of annual precipitation in Ningxia.[Method] Using rotated empirical orthogonal function,the precipitation concentration index,wavelet analysis and Mann-Kendall rank statistic method,the characteristics of precipitation on the spatial-temporal variability and trend were analyzed by the monthly precipitation series in Ningxia during 1951-2008.[Result] In Ningxia,the spatial structural patterns of annual precipitation appeared 'North-south type' and 'North-center-south type'.It increased from north to south,the changes of interannual precipitation decreased from north to south.Precipitation changed significantly in month and distributed differently in the Yellow River irrigation area.But it was conversely steady in central arid zone and mountainous area of southern Ningxia.The probability of single abundant precipitation year was higher than single short precipitation year and the continuous short precipitation year was higher than continuous abundant precipitation year.The main cycles were 3a,6a and 10a approximately.In the mid arid zone and the mountainous area of southern Ningxia,the probability of precipitation reduction was about 75% and the Yellow river irrigation area,71.4%,respectively.The reduction in the entire area was about 73.3%.The annual precipitation in the middle arid area and irrigation area was increasing.The variability would change slowly for the intra-annual distribution of precipitation.Especially,the reduction tendency rate in the middle arid area reached 100.0%.[Conclusion] The study provided references for the effective utilization of the local precipitation,and the coordinated development of the regional social economy and ecological environment.展开更多
The precipitation regime of the low latitude highlands of Yunnan in Southwest China is subject to the interactions between the East Asian Summer Monsoon and the Indian Summer Monsoon, and the influence of surface orog...The precipitation regime of the low latitude highlands of Yunnan in Southwest China is subject to the interactions between the East Asian Summer Monsoon and the Indian Summer Monsoon, and the influence of surface orography. An understanding of changes in its spatial and temporal patterns is urgently needed for climate change projection, hydrologi- cal impact modelling, and regional and downstream water resources management. Using daily precipitation records of the low latitude highlands over the last several decades （1950s-2007）, a time series of precipitation indices, including annual precipitation, number of rainy days, mean annual precipitation intensity, the dates of the onset of the rainy season, degree and period of precipitation seasonal concentration, the highest 1-day, 3-day and 7-day precipitation, and precipitation amount and number of rainy days for precipitation above dif- ferent intensities （such as 〉~10 mm, 〉~25 mm and 〉~50 mm of daily precipitation）, was con- structed. The Trend-Free Pre-Whitening Mann-Kendall trend test was then used to detect trends of the time series data. The results show that there is no significant trend in annual precipitation and strong seasonal differentiation of precipitation trends across the low latitude highlands. Springs and winters are getting wetter and summers are getting drier. Autumns are getting drier in the east and wetter in the west. As a consequence, the seasonality of pre- cipitation is weakening slightly. The beginning of the rainy season and the period of the highest precipitation tend to be earlier. In the meantime, the low latitude highlands has also witnessed less rainy days, more intense precipitation, slightly longer moderate and heavy precipitation events, and more frequent extreme precipitation events. Additionally, regional differentiation of precipitation trends is remarkable. These variations may be associated with weakening of the East Asian summer monsoon and strengthening of the South Asian summer monsoon, as well as the ＂corridor-barrier＂ effects of special mountainous terrain. However, the physical mechanisms involved still need to be uncovered in the future.展开更多
Cost-benefit analysis and breakeven point were used to analyze the production cost and economic benefit of tilapia pond monoculture and polyculture.From the aspects of tilapia production and economic benefit,this pape...Cost-benefit analysis and breakeven point were used to analyze the production cost and economic benefit of tilapia pond monoculture and polyculture.From the aspects of tilapia production and economic benefit,this paper summarized the current production status and the characteristics of tilapia industry development and analyzed its developing trend.The results indicated that feed cost,pond rates and labor cost are the main production costs,and the production cost of polyculture is significantly lower than that of monoculture.Through comparative analysis,it is proposed that the tilapia industry should be reasonably guided to the intensive,standardized and pollution-free direction.Specifically,it is necessary to improve the coverage of improved varieties,strengthen disease prevention and control and promote the healthy farming model of tilapia.We also should strengthen the training of tilapia production techniques and the quality and safety testing of tilapia products,and accelerate the development of tilapia industrialization,so as to promote the sustainable and healthy development of tilapia industry.展开更多
To search for the Design Patterns’ influence on the software, the paper abstracts the feature models of 9 kinds of classic exiting design patterns among the 23 kinds and describes the features with algorithm language...To search for the Design Patterns’ influence on the software, the paper abstracts the feature models of 9 kinds of classic exiting design patterns among the 23 kinds and describes the features with algorithm language. Meanwhile, searching for the specific structure features in the network, the paper designs 9 matching algorithms of the 9 kinds design patterns mentioned above to research on the structure of the design patterns in the software network. At last, the paper analyzes the evolving trends of the software scale and the application frequency of the 9 kinds of design patterns as the software evolves, and search for the rules how these design patterns are applied into 4 kinds of typical software.展开更多
文摘Landscape pattern is a widely used concept for the demonstration of landscape characteristic features. The integral spatial distribution trend of landscape elements is interested point in the landscape ecological research, especially in those of complex secondary forest regions with confusing mosaics of land cover. Trend surface analysis which used in community and population ecological researches was introduced to reveal the landscape pattern. A reasonable and reliable approach for application of trend surface analysis was provided in detail. As key steps of the approach, uniform grid point sampling method was developed. The efforts were also concentrated at an example of Guandishan forested landscape. Some basic rules of spatial distribution of landscape elements were exclaimed. These will be benefit to the further study in the area to enhance the forest sustainable management and landscape planning.
文摘In this paper, first, based on landscape ecology theories, we respectively selected indexes from 4 aspects, area, edge, shape, and density, of the landscape type to describe the status of forest landscape patterns, and we established the stability index of landscape pattern (LSBI). Then, based on geo-statistical theories, we divided the forest in the reservoir area into 3990 grids of 4 km × 4 km using network technology and employing ordinary Kriging modelling to make trend surface analyses of the forest resources in the reservoir area. Finally, based on statistics principles, we used sampling theory to systematically extract 227 samples to obtain 7 periods of remote-sensing data from 1990a to 2012a. Then, we classified and extracted the forest in the sampling area using remote sensing, and we analysed each result with an Autoregressive Integrated Moving Average Model (ARIMA) time-series model. The results indicated the following: 1) the landscape structure of the reservoir area was primarily needle-leaved forest, broad-leaved forest and bush forest, and the mixed stands and bamboo stands were secondary;2) the difference of the forest landscape pattern stability in the reservoir area, in all directions, was not significant, but the southern region was slightly more stable;and 3) the stability of the forest landscape pattern in the reservoir area increased from 1990a to 2012a. It kept increasing until 2016a. This study provides a theoretical basis for the reasonable management and decisions about the forest resources in the Three Gorges Reservoir Area. Meanwhile, it also explores methods for relevant research and has practical significance.
文摘Background: Salivary gland tumours (SGTs) are rare, but recent reports suggest an increasing incidence. Although there are previous Nigerian studies on the patterns of SGTs, patterns and trends of disease may change over time. The aim of this study was to describe the pattern of presentation of SGTs, and to determine the trends in occurrence of SGTs at Federal Teaching Hospital (FTH), Gombe over a period of 15 years. Method: This descriptive study included cases of histologically diagnosed SGTs from January 2008 to December 2022. Relevant information (age, gender, site, year of diagnosis, and histopathologic diagnosis) was extracted from the cancer registers and histopathologic records. The lesions were then categorized into benign and malignant SGTs and grouped into three groups spanning 5 years each based on the year of diagnosis. Data analysis was done using IBM SPSS version 23, and p ≤ 0.05 was considered statistically significant. Results: There were 93 (61.2%) benign and 59 (38.8%) malignant SGTs. Benign SGTs had a mean age of 36.4 ± 13.6 years, and were more common in females (57.0%), and in the parotid (41.9%). Pleomorphic adenoma (94.6%) was the most common benign SGT. Malignant SGTs had a mean age of 44.5 ± 18.4 years, with male predilection (54.2%) and occurrence mostly in the palate (27.6%) and parotid (22.4%). Mucoepidermoid carcinoma (39.0%) and adenoid cystic carcinoma (32.2%) were the most frequent malignant SGTs. The mean age of occurrence of malignant SGTs was significantly higher than that of benign SGTs (p = 0.005). The trend analysis showed that there has been a steady rise in the proportion of males presenting with malignant SGTs. Similarly, there has been a steady increase in the frequency of benign SGTs in the parotid. The palate was the predominant site for the malignant SGTs between 2008 and 2012, but in the last five years (2018 to 2022), the parotid has become the predominant site. Over the duration of the study, the ratio of benign to malignant SGTs has remained relatively constant. Conclusion: While the overall pattern of presentation of SGTs in Gombe is similar to reports in the literature, this study has identified some changes in trends over the years.
文摘The identification of control chart patterns is very important in statistical process control. Control chart patterns are categorized as natural and unnatural. The presence of unnatural patterns means that a process is out of statistical control and there are assignable causes for process variation that should be investigated. This paper proposes an artificial neural network algorithm to identify the three basic control chart patterns;natural, shift, and trend. This identification is in addition to the traditional statistical detection of runs in data, since runs are one of the out of control situations. It is assumed that a process starts as a natural pattern and then may undergo only one out of control pattern at a time. The performance of the proposed algorithm was evaluated by measuring the probability of success in identifying the three basic patterns accurately, and comparing these results with previous research work. The comparison showed that the proposed algorithm realized better identification than others.
基金funded by National Natural Science Foundation of China (No. 81000754)a grant from the Key Laboratory for Laboratory Medicine of Jiangsu Province of China (No. XK201114)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Shigellosis causes diarrheal disease in humans in both developed and developing countries, and multi-drug resistance in Shigella is an emerging problem. Understanding changing resistance patterns is important in determining appropriate antibiotic treatments. This meta-analysis systematically evaluated aminoglycoside resistance in Shigella. A systematic review was constructed based on MEDLINE and EMBASE databases. Randomeffect models or fixed-effect models were used based on P value considering the possibility of heterogeneity between studies for meta-analysis. Data manipulation and statistical analyses were performed using software STATA 11.0. By means of meta-analysis, we found a lower resistance to three kinds of aminoglycosides in the Europe-America areas during the 12 year study period than that of the Asia-Africa areas. Kanamycin resistance was observed to be the most common drug resistance among Shigella isolates with a prevalence of 6.88% （95%CI： 6.36%-7.43%）. Comparison of data from Europe-America and Asia-Africa areas revealed that Shigella flexneri resistance was greater than the resistance calculated for Shigella sonnei. Importantly, Shigella sonnei has played a significant role in aminoglycoside-resistance in recent years. Similarly, data showed that resistance to these drugs in children was higher than the corresponding data of adults. In conclusion, aminoglycoside-resistant Shigella is not an unusual phenomenon worldwide. Distribution in Shigella resistance differs sharply based on geographic areas, periods of time and subtypes. The results from the present study highlight the need for con- tinuous surveillance of resistance and control of antibiotic usage.
基金supported by the National Basic Research Program of China(No.2010CB428401)National Natural Science Foundation of China(No40911130506)
文摘Based on observed daily precipitation data of 540 stations and 3,839 gridded data from the high-resolution regional climate model COSMO-Climate Limited-area Modeling(CCLM)for 1961–2000,the simulation ability of CCLM on daily precipitation in China is examined,and the variation of daily precipitation distribution pattern is revealed.By applying the probability distribution and extreme value theory to the projected daily precipitation(2011–2050)under SRES A1B scenario with CCLM,trends of daily precipitation series and daily precipitation extremes are analyzed.Results show that except for the western Qinghai-Tibetan Plateau and South China,distribution patterns of the kurtosis and skewness calculated from the simulated and observed series are consistent with each other;their spatial correlation coefcients are above 0.75.The CCLM can well capture the distribution characteristics of daily precipitation over China.It is projected that in some parts of the Jianghuai region,central-eastern Northeast China and Inner Mongolia,the kurtosis and skewness will increase significantly,and precipitation extremes will increase during 2011–2050.The projected increase of maximum daily rainfall and longest non-precipitation period during flood season in the aforementioned regions,also show increasing trends of droughts and floods in the next 40 years.
基金National Basic Research Program of China （973 Program）, No.2012CB95570001 Key Research Program of the Chinese Academy of Sciences, No.KZZD-EW-06-04+1 种基金 National Natural Science Foundation of China, No.41301121 National Key Technologies R＆D Program of China, No.2012BAJ15B02
文摘Migration plays an increasing role in China＇s economy since mobility rose and economic restructuring has proceeded during the last three decades. Given the background of most studies focusing on migration in a particular period, there is a critical need to analyze the spatial-temporal patterns of migration. Using bicomponent trend mapping technique and interprovincial migration data during the periods 1985-1990, 1990-1995, 1995-2000, 2000- 2005, and 2005-2010 we analyze net-, in-, out-migration intensity, and their changes over time in this study. Strong spatial variations in migration intensity were found in China＇s interprovincial migration, and substantial increase in migration intensity was also detected in eastern China during 1985-2010. Eight key destinations are mostly located within the three rapidly growing economic zones of eastern China （Pearl River Delta, Yangtze River Delta and Beijing-Tianjin-Hebei Metropolitan Region）, and they are classified into three types： mature, emerging, and fluctuant origins, while most key origins are relatively undeveloped central and western provinces, which are exactly in accordance with China＇s economic development patterns. The results of bicomponent trend mapping indicate that, in a sense, the migration in the south was more active than the north over the last three decades. The result shows the new changing features of spatial-temporal patterns of China＇s interprovincial migration that Fan and Chen did not find out in their research. A series of social-economic changes including rural transformation, balanced regional development, and labor market changes should be paid more attention to explore China＇s future interprovincial migration.
文摘This study analyzed the spatial distribution and temporal trends of precipitation and its extremes over Nigeria from 1979-2013 using climate indices, in order to assess climatic extremes in the country. Daily precipitation data used in this study were obtained from Nigeria Meteorological Agency (NIMET), Lagos. The study used climate indices developed by the Expert Team on Climate Change Detection (ETCCDI) for assessing extreme precipitation. Sen’s slope estimator and Mann-Kendall trend test were employed in data analysis. Results revealed that precipitation and its extremes varied spatially across Nigeria. Significant negative trends were observed in most of the precipitation indices for the period under study. Furthermore, significant downward trends were observed in the CWD (Consecutive Wet Day) while the CDD (Consecutive Dry Day) showed significant upward trends in all the regions. These spatial and temporal changes indicate that Nigeria’s climate is trending towards a warmer and drier condition, which could be attributed to global warming-induced climate change;which altered historical rainfall patterns thereby leading to extreme events. The findings of this study have provided useful information in understanding the extreme events that are assumed by the general populace to be normal recurrent events in Nigeria. The results of the analysis of yearly and decadal changes in precipitation totals and extreme values for the last 35 years (1979-2013) suggest the likelihood of severe impacts on water resources, agriculture, and water-sensitive economic activities
基金Supported by Ningxia Natural Science Fund (NZ10215)National Science and Technology Planning Project (2011BAD29B07)Ningxia Natural Science Fund (NZ10214)
文摘[Objective] The aim was to study the characteristics of the spatial structural patterns and temporal variability of annual precipitation in Ningxia.[Method] Using rotated empirical orthogonal function,the precipitation concentration index,wavelet analysis and Mann-Kendall rank statistic method,the characteristics of precipitation on the spatial-temporal variability and trend were analyzed by the monthly precipitation series in Ningxia during 1951-2008.[Result] In Ningxia,the spatial structural patterns of annual precipitation appeared 'North-south type' and 'North-center-south type'.It increased from north to south,the changes of interannual precipitation decreased from north to south.Precipitation changed significantly in month and distributed differently in the Yellow River irrigation area.But it was conversely steady in central arid zone and mountainous area of southern Ningxia.The probability of single abundant precipitation year was higher than single short precipitation year and the continuous short precipitation year was higher than continuous abundant precipitation year.The main cycles were 3a,6a and 10a approximately.In the mid arid zone and the mountainous area of southern Ningxia,the probability of precipitation reduction was about 75% and the Yellow river irrigation area,71.4%,respectively.The reduction in the entire area was about 73.3%.The annual precipitation in the middle arid area and irrigation area was increasing.The variability would change slowly for the intra-annual distribution of precipitation.Especially,the reduction tendency rate in the middle arid area reached 100.0%.[Conclusion] The study provided references for the effective utilization of the local precipitation,and the coordinated development of the regional social economy and ecological environment.
基金National Natural Science Foundation of China, No.41061010 National Science and Technology Support Program, No.2013BAB06B03 No.2011BAC09B07
文摘The precipitation regime of the low latitude highlands of Yunnan in Southwest China is subject to the interactions between the East Asian Summer Monsoon and the Indian Summer Monsoon, and the influence of surface orography. An understanding of changes in its spatial and temporal patterns is urgently needed for climate change projection, hydrologi- cal impact modelling, and regional and downstream water resources management. Using daily precipitation records of the low latitude highlands over the last several decades （1950s-2007）, a time series of precipitation indices, including annual precipitation, number of rainy days, mean annual precipitation intensity, the dates of the onset of the rainy season, degree and period of precipitation seasonal concentration, the highest 1-day, 3-day and 7-day precipitation, and precipitation amount and number of rainy days for precipitation above dif- ferent intensities （such as 〉~10 mm, 〉~25 mm and 〉~50 mm of daily precipitation）, was con- structed. The Trend-Free Pre-Whitening Mann-Kendall trend test was then used to detect trends of the time series data. The results show that there is no significant trend in annual precipitation and strong seasonal differentiation of precipitation trends across the low latitude highlands. Springs and winters are getting wetter and summers are getting drier. Autumns are getting drier in the east and wetter in the west. As a consequence, the seasonality of pre- cipitation is weakening slightly. The beginning of the rainy season and the period of the highest precipitation tend to be earlier. In the meantime, the low latitude highlands has also witnessed less rainy days, more intense precipitation, slightly longer moderate and heavy precipitation events, and more frequent extreme precipitation events. Additionally, regional differentiation of precipitation trends is remarkable. These variations may be associated with weakening of the East Asian summer monsoon and strengthening of the South Asian summer monsoon, as well as the ＂corridor-barrier＂ effects of special mountainous terrain. However, the physical mechanisms involved still need to be uncovered in the future.
基金Supported by the 2018 Guangxi Young and Middle-aged Teachers’Basic Ability Improvement Project(2018KY0612)the Independent Research Project of Guangxi Key Laboratory Beibu Gulf Marine Biodiversity Conservation(2018ZB05)+2 种基金High-level Talent Research Start-up Project of Qinzhou University(2017KYQD215)2018 Guangxi Higher Education Reform Project(2018JGB334)Special Fund for Specially-invited Experts in Guangxi
文摘Cost-benefit analysis and breakeven point were used to analyze the production cost and economic benefit of tilapia pond monoculture and polyculture.From the aspects of tilapia production and economic benefit,this paper summarized the current production status and the characteristics of tilapia industry development and analyzed its developing trend.The results indicated that feed cost,pond rates and labor cost are the main production costs,and the production cost of polyculture is significantly lower than that of monoculture.Through comparative analysis,it is proposed that the tilapia industry should be reasonably guided to the intensive,standardized and pollution-free direction.Specifically,it is necessary to improve the coverage of improved varieties,strengthen disease prevention and control and promote the healthy farming model of tilapia.We also should strengthen the training of tilapia production techniques and the quality and safety testing of tilapia products,and accelerate the development of tilapia industrialization,so as to promote the sustainable and healthy development of tilapia industry.
文摘To search for the Design Patterns’ influence on the software, the paper abstracts the feature models of 9 kinds of classic exiting design patterns among the 23 kinds and describes the features with algorithm language. Meanwhile, searching for the specific structure features in the network, the paper designs 9 matching algorithms of the 9 kinds design patterns mentioned above to research on the structure of the design patterns in the software network. At last, the paper analyzes the evolving trends of the software scale and the application frequency of the 9 kinds of design patterns as the software evolves, and search for the rules how these design patterns are applied into 4 kinds of typical software.
