In order to suppress the white noise interference in partial discharge(PD)detection and accurately extract the characteristics of local discharge pulse acoustic signal of transformer under strong noise environment,the...In order to suppress the white noise interference in partial discharge(PD)detection and accurately extract the characteristics of local discharge pulse acoustic signal of transformer under strong noise environment,the adaptive separation and denoising of the discharge pulse acoustic signal were analyzed under low signal-to-noise ratio(SNR)environment.Firstly,the optimal decomposition mode number K of the variational mode decomposition(VMD)was determined based on Spearman correlation coefficient,then the reliability of the proposed Spearman-variational mode decomposition(SVMD)method decomposition was verified by simulated signals,and finally the actual discharge pulse acoustic signal was decomposed and denoised based on the Spearman correlation coefficient averaging threshold method to extract the eigenmode function components of the discharge pulse signal.The results showed that SVMD adaptively solved the unknown defects of VMD mode number,and effectively extracted the modal components of complex signals,and successfully realized the denoising of transformer partial discharge acoustic signals.The proposed method effectively removed white noise interference in the partial discharge acoustic signal and obtained a smooth filtered signal.It retained the integrity of the partial discharge signal to the maximum extent and was beneficial to the subsequent research of partial discharge.The improvement of VMD was helpful to promote its wide use in industrial equipment condition inspection.展开更多
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
Guided waves based damage detection methods using base signals offer the advantages of simplicity of signal generation and reception,sensitivity to damage,and large area coverage;however,applications of the technology...Guided waves based damage detection methods using base signals offer the advantages of simplicity of signal generation and reception,sensitivity to damage,and large area coverage;however,applications of the technology are limited by the sensitivity to environmental temperature variations.In this paper,a Spearman Damage Index-based damage diagnosis method for structural health condition monitoring under varying temperatures is presented.First,a PZT sensor-based Guided wave propagation model is proposed and employed to analyze the temperature effect.The result of the analysis shows the wave speed of the Guided wave signal has higher temperature sensitivity than the signal fluctuation features.Then,a Spearman rank correlation coefficient-based damage index is presented to identify damage of the structure under varying temperatures.Finally,a damage detection test on a composite plate is conducted to verify the effectiveness of the Spearman Damage Index-based damage diagnosis method.Experimental results show that the proposed damage diagnosis method is capable of detecting the existence of the damage and identify its location under varying temperatures.展开更多
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
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
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), São 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
This paper addresses the issues of replenishment and pricing of vegetable commodities in fresh food supermarkets.By analyzing sales data and loss rate data,mathematical models are established to solve the following pr...This paper addresses the issues of replenishment and pricing of vegetable commodities in fresh food supermarkets.By analyzing sales data and loss rate data,mathematical models are established to solve the following problems.Spearman correlation analysis and cluster analysis methods are employed.Firstly,data preprocessing is conducted by excluding returned vegetable products from a certain supermarket’s distribution,and then integrating sales transaction details and wholesale price-related data.Secondly,monthly data is used to succinctly present the sales distribution patterns of various categories and individual items of vegetables through line charts.Finally,the models of Spearman correlation analysis and cluster analysis are respectively applied to illustrate the relationship between the sales volume of 6 major categories of vegetables and 251 individual items.Linear regression models,time series analysis,and XG-Boost regression analysis models are used.This paper requires replenishment plans to be made by category,analyzing the relationship between the total sales volume and cost-plus pricing of various vegetable categories.Firstly,a linear regression model is applied to fit historical sales volume and cost-plus pricing,resulting in a linear functional relationship,indicating that only the sales volume of tomatoes is negatively correlated with cost-plus pricing.Based on historical sales data,the daily replenishment total for each vegetable category within the next week is predicted.Predictive models and time series analysis are employed.Meanwhile,for pricing strategies,the XGBoost algorithm is utilized to provide reasonable pricing strategies.Based on the optimal solution,replenishment plans and pricing strategies for the next week are formulated to ensure the maximization of sales revenue objectives.展开更多
基金supported by State Grid Gansu Electric Power Research Institute(No.52272219000Q).
文摘In order to suppress the white noise interference in partial discharge(PD)detection and accurately extract the characteristics of local discharge pulse acoustic signal of transformer under strong noise environment,the adaptive separation and denoising of the discharge pulse acoustic signal were analyzed under low signal-to-noise ratio(SNR)environment.Firstly,the optimal decomposition mode number K of the variational mode decomposition(VMD)was determined based on Spearman correlation coefficient,then the reliability of the proposed Spearman-variational mode decomposition(SVMD)method decomposition was verified by simulated signals,and finally the actual discharge pulse acoustic signal was decomposed and denoised based on the Spearman correlation coefficient averaging threshold method to extract the eigenmode function components of the discharge pulse signal.The results showed that SVMD adaptively solved the unknown defects of VMD mode number,and effectively extracted the modal components of complex signals,and successfully realized the denoising of transformer partial discharge acoustic signals.The proposed method effectively removed white noise interference in the partial discharge acoustic signal and obtained a smooth filtered signal.It retained the integrity of the partial discharge signal to the maximum extent and was beneficial to the subsequent research of partial discharge.The improvement of VMD was helpful to promote its wide use in industrial equipment condition inspection.
基金Supported by State Council Special Fund for Pollution Sources Survey (WPXC2007C200)~~
文摘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.
基金This work was supported by the National Key Research and Development Program of China(2018YFA0702800)the National Natural Science Foundation of China(51805068).
文摘Guided waves based damage detection methods using base signals offer the advantages of simplicity of signal generation and reception,sensitivity to damage,and large area coverage;however,applications of the technology are limited by the sensitivity to environmental temperature variations.In this paper,a Spearman Damage Index-based damage diagnosis method for structural health condition monitoring under varying temperatures is presented.First,a PZT sensor-based Guided wave propagation model is proposed and employed to analyze the temperature effect.The result of the analysis shows the wave speed of the Guided wave signal has higher temperature sensitivity than the signal fluctuation features.Then,a Spearman rank correlation coefficient-based damage index is presented to identify damage of the structure under varying temperatures.Finally,a damage detection test on a composite plate is conducted to verify the effectiveness of the Spearman Damage Index-based damage diagnosis method.Experimental results show that the proposed damage diagnosis method is capable of detecting the existence of the damage and identify its location under varying temperatures.
基金Supported by the Science and Technology Plan Project of Liupanshui City(52020-2015-30).
文摘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.
基金Supported by Science and Technology Open Research Fund Project of Guizhou Meteorological Bureau(KF[2009]08)。
文摘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.
文摘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), São 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.
文摘This paper addresses the issues of replenishment and pricing of vegetable commodities in fresh food supermarkets.By analyzing sales data and loss rate data,mathematical models are established to solve the following problems.Spearman correlation analysis and cluster analysis methods are employed.Firstly,data preprocessing is conducted by excluding returned vegetable products from a certain supermarket’s distribution,and then integrating sales transaction details and wholesale price-related data.Secondly,monthly data is used to succinctly present the sales distribution patterns of various categories and individual items of vegetables through line charts.Finally,the models of Spearman correlation analysis and cluster analysis are respectively applied to illustrate the relationship between the sales volume of 6 major categories of vegetables and 251 individual items.Linear regression models,time series analysis,and XG-Boost regression analysis models are used.This paper requires replenishment plans to be made by category,analyzing the relationship between the total sales volume and cost-plus pricing of various vegetable categories.Firstly,a linear regression model is applied to fit historical sales volume and cost-plus pricing,resulting in a linear functional relationship,indicating that only the sales volume of tomatoes is negatively correlated with cost-plus pricing.Based on historical sales data,the daily replenishment total for each vegetable category within the next week is predicted.Predictive models and time series analysis are employed.Meanwhile,for pricing strategies,the XGBoost algorithm is utilized to provide reasonable pricing strategies.Based on the optimal solution,replenishment plans and pricing strategies for the next week are formulated to ensure the maximization of sales revenue objectives.
