The data acquisition technologies used in power systems have been continuously improving,thus laying the solid foundation for data-driven operation analysis of power systems.However,existing methods for analyzing the ...The data acquisition technologies used in power systems have been continuously improving,thus laying the solid foundation for data-driven operation analysis of power systems.However,existing methods for analyzing the relationship between operational variables mainly depend on the mathematical model and element parameters of the power system.Therefore,a thorough data-based analysis method is required to investigate the spatiotemporal characteristics of power system operation,especially for new types of power systems.The causal inference method,which has been successfully applied in many fields,is a powerful tool for investigating the interaction of data variables.In this study,a causal inference method is proposed based on supervisory control and data acquisition(SCADA)data for investigating the spatiotemporal causal relationships in power systems.Initially,a multiple data-sequence regression model is proposed to analyze the relationship of operation data variables.Next,the linear non-Gaussian acyclic model(LiNGAM)is used to calculate the causal index of the operational variables,and its limitations are analyzed.Furthermore,a new causal index of“full variable amplitude LiNGAM(FVA-LiNGAM)”is proposed by incorporating prior causal direct knowledge and considering the effect of real variable amplitude.Using the FVA-LiNGAM causal index,the causal relationship of operation variables can be investigated with higher spatiotemporal accuracy than that of the original LiNGAM index.Taking a real SCADA data subset of a provincial power system as an example,the validity of the FVA-LiNGAM causal index is verified.The variation patterns in spatiotemporal causality are explored using actual SCADA data sequences.The result shows that there indeed exists some spatiotemporal causality variation patterns between the operating variables of the power system.展开更多
Life in desert ecosystems drives animals to adapt their surface locomotor activity according to environmental conditions. In this study, the hourly and monthly variations in the surface activity patterns of the terres...Life in desert ecosystems drives animals to adapt their surface locomotor activity according to environmental conditions. In this study, the hourly and monthly variations in the surface activity patterns of the terrestrial crustacean Hemilepistus reaumurii were investigated. The surface activity of H. reaumurii at the population scale was observed by collecting the hourly active individuals from the sunrise to the sunset of the studied day in each month of 2013 in the Bchachma locality, Tunisia. The collected active individuals were put in perspex boxes（on which we labeled the hourly time interval in which the individuals were collected） in the field and then transported to the laboratory for analysis. Individuals were counted, sexed, and measured in the laboratory. Despite desert conditions in the studied site, H. reaumurii was characterized by a diurnal surface activity, showing a bimodal pattern during the warm months（i.e., May to October）. However, it exhibited a unimodal surface activity pattern in the cold months（i.e., February, March, and November）. The surface activity was significantly correlated with sunrise and sunset. Moreover, a significant quadratic effect of temperature on the surface activity of H. reaumurii was observed. Furthermore, the study showed that the most important surface activity was recorded in March. The daily exploitation of the temporal niches was significantly different as a function of months. The body size of males was larger than that of females, and the body size of active individuals changed with months. All these behavioural changes in the surface activity represent an adaptive strategy of life in the arid environment.展开更多
Dear Editor,We have read and reviewed the article entitled＂The diurnal variation pattern of choroidal thickness in macular region of young healthy female individuals using spectral domain optical coherence tomography...Dear Editor,We have read and reviewed the article entitled＂The diurnal variation pattern of choroidal thickness in macular region of young healthy female individuals using spectral domain optical coherence tomography＂by Zhao et al^（[1]）with great interest.展开更多
The TEEOF method that expands temporally is used to conduct a diagnostic study of the variation patterns of 1, 3, 6 and 10 years with regard to mean air temperature over the globe and Southern and Northern Hemispheres...The TEEOF method that expands temporally is used to conduct a diagnostic study of the variation patterns of 1, 3, 6 and 10 years with regard to mean air temperature over the globe and Southern and Northern Hemispheres over the course of 100 years. The results show that the first mode of TEEOF takes up more than 50% in the total variance, with each of the first mode in the interannual oscillations generally standing for annually varying patterns which are related with climate and reflecting long-term tendency of change in air temperature. It is particularly true for the first mode on the 10-year scale, which shows an obvious ascending trend concerning the temperature in winter and consistently the primary component of time goes in a way that is very close to the sequence of actual temperature. Apart from the first mode of all time sections of TEEOF for the globe and the two hemispheres and the second mode of the 1-year TEEOF, interannual variation described by other characteristic vectors are showing various patterns, with corresponding primary components having relation with long-term variability of specific interannual quasi-periodic oscillation structures. A 2T test applied to the annual variation pattern shows that the abrupt changes for the Southern Hemisphere and the globe come closer to the result of a uni-element t test for mean temperature than those for the Northern Hemisphere do. It indicates that the 2Ttest, when carried out with patterns of multiple variables, seems more reasonable than the t test with single elements.展开更多
Variations of wood specific gravity and extractive contents from pith to bark and from base to the top of tree were investigated in a 14-year-old commercial pulpwood species Sterculia setigera Del. Growing in savanna ...Variations of wood specific gravity and extractive contents from pith to bark and from base to the top of tree were investigated in a 14-year-old commercial pulpwood species Sterculia setigera Del. Growing in savanna zone in Nigeria. Tree mean specific gravity averaged 0.37; wood at the base had significant higher specific gravity than those at the top while it increased from pith to bark. For extractive content mean value was 1.20% for wood and 1.72% for bark; i[t varied significantly between trees and from base of the tree to the top and from pith to the bark. Extractive content at the butt and breast height is more than double of the value at the top of the tree. The high extractive content at the base is similar to high specific gravity observed for wood samples from the base. Extractive content of the bast was significantly higher than that of the wood. The low specific gravity show possible suitability of the species for paper making in Nigerian paper mills. The wood of Sterculia setigera showed a significant variation between- and within-trees in the two properties considered, though the wood is light with low extractive content; it is however a potential raw material for large scale pulpwood production in Nigeria.展开更多
Instrument neutron activation analysis (INAA) has been employed in this study to determine 32 elements in soil on the loess plateau. The preliminary results suggest that geochemical characteristics of elements in the ...Instrument neutron activation analysis (INAA) has been employed in this study to determine 32 elements in soil on the loess plateau. The preliminary results suggest that geochemical characteristics of elements in the soil mainly retained those in the parent materials (loess). It has been found that fractional deposition among grain sizes in the process of loess transportation as well as the bioclimate in which the soil developed are main factors affecting the regional variations of elemental distribution in soil on the plateau. Contour maps of element concentrations plotted from the trend analyses exhibit the major patterns of the distributions and variations on the plateau. Furthermore, the study also provides evidence for the aeolian theory of the loess transportation in China.展开更多
Subject Code:C01The United Nations estimates that world population will increase to 11.2billion in the year 2100.Vegetative oil that serves as one of the major energy resources is essential to feeding human beings.Oil...Subject Code:C01The United Nations estimates that world population will increase to 11.2billion in the year 2100.Vegetative oil that serves as one of the major energy resources is essential to feeding human beings.Oil palm(Elaeis guineensis Jacq,Elaeis from ancient Greek,meaning'oil')produces more than 13times the yield of oil/year/hectare of soybean,one major human annual oil crop.In consequence,it represents a展开更多
By means of simulation experiments with a two-dimensional zonal-mean model,a study is made of the influence of the western North-Pacific midlatitude sea-surface temperature(SST)anomalies on the circulation pattern and...By means of simulation experiments with a two-dimensional zonal-mean model,a study is made of the influence of the western North-Pacific midlatitude sea-surface temperature(SST)anomalies on the circulation pattern and wet-seasonal precipitation over the East-China Changjiang-Huaihe reaches and the North-China plain.The SST anomalies are divided into two types,one being“colder in the south and warmer in the north”and the other just opposite,depending on season.Results show that the occurrence of the anomalies is followed by considerable changes in the position of the subtropical high happening for 3-5 months to come.For instance,the spring“colder in the south and warmer in the north”anomalous type (i.e.,colder for 20—35°N,and warmer north of 35°N)leads to the intensification of the summer subtropical high,with the ridge line moved slightly northward,resulting in drought over Changjiang reaches for July-August and in excessive rainfall in the North-China plain,and vice versa.展开更多
The accelerated demand for engineering services has led to the extensive utilization of engineering blasting techniques.Blasting-induced changes in loess microstructure(e.g.particle breakage,pore structure change)dire...The accelerated demand for engineering services has led to the extensive utilization of engineering blasting techniques.Blasting-induced changes in loess microstructure(e.g.particle breakage,pore structure change)directly affect its macroscopic mechanical properties.However,there remains a notable lack of studies on the impact of explosions on loess microstructure and the quantificationof loess microstructure.This study employed micro-computed tomography(μ-CT)technology to examine loess samples extracted from the surrounding area of the explosion cavity,systematically investigating the volume,orientation,and morphological characteristics of particles and pores.The research findings indicated that the explosion caused a break for the particles with a diameter larger than 10μm,and the number of smaller particles increased.Blasting decreased the particle sphericity and orientation angle.The reduction in porosity was primarily attributed to a decrease in the volume of both macropores and mesopores,with a greater reduction in the volume of mesopores.Although the number of micropores increased,the volume change was insignificant.Furthermore,the explosion increased the pore fractal dimension and patch density,suggesting a more complex and fragmented pore structure.Moreover,the pore throat radius and channel length decreased with decreasing distance from the explosion cavity(D_(EC)),indicating that the pore's connectivity reduced.The radius of the blasting cavity was approximately 0.35 m.Additionally,the loess zone surrounding the blasting cavity was divided into failure,plastic,and elastic zones using the D_(EC)=0.2 m and 1.2 m as the boundaries.The impacts of the explosion on loess were mainly within the range of D_(EC)less than 1.20 m.The analysis of the traits,patterns,and mechanisms of explosions'impact on the loess's microstructure can provide microscopic insight into the macro-dynamic behavior,assess the impact of explosions on the surrounding loess,and identify the potential geological hazards triggered by blasting,which offers a theoretical foundation for the subsequent engineering design and security measures.展开更多
Microfibril angle （MFA） in Chinese fir was tested by X-ray diffraction apparatus and calculated by computer software. The results were as follows： MFA was controlled strongly by inheritance, and there was no signif...Microfibril angle （MFA） in Chinese fir was tested by X-ray diffraction apparatus and calculated by computer software. The results were as follows： MFA was controlled strongly by inheritance, and there was no significant difference in MFA among interspecies, juvenile and mature wood. In the longitudinal, MFA reduces with the height rising from 0 to 5.5 m, especially in the heights from 0 to 1.5 m. The values of MFA are nearly consistence from 1.5 to 7.5 m. The variation range was between 10.82°and 12.57°from 1.5 to 7.5 m, R2 of power equation achieved 0.932 1, and analysis of variance indicated that the variation of MFA was not significant from 1.5 to 7.5 m, The age of the trees had an important influence on MFA, consequently, the difference in MFA was significant among annual rings in radial, which was maximal in near pith and reduced rapidly from the pith to sapwood, and its decline tendency was slow beyond the ninth annual ring. MFA reached minimum value at the 15th annual ring, and the difference reached more than 20° and R^2 of binomial equation achieved 0.755 6.展开更多
基金supported by the National Natural Science Foundation of China(51877034).
文摘The data acquisition technologies used in power systems have been continuously improving,thus laying the solid foundation for data-driven operation analysis of power systems.However,existing methods for analyzing the relationship between operational variables mainly depend on the mathematical model and element parameters of the power system.Therefore,a thorough data-based analysis method is required to investigate the spatiotemporal characteristics of power system operation,especially for new types of power systems.The causal inference method,which has been successfully applied in many fields,is a powerful tool for investigating the interaction of data variables.In this study,a causal inference method is proposed based on supervisory control and data acquisition(SCADA)data for investigating the spatiotemporal causal relationships in power systems.Initially,a multiple data-sequence regression model is proposed to analyze the relationship of operation data variables.Next,the linear non-Gaussian acyclic model(LiNGAM)is used to calculate the causal index of the operational variables,and its limitations are analyzed.Furthermore,a new causal index of“full variable amplitude LiNGAM(FVA-LiNGAM)”is proposed by incorporating prior causal direct knowledge and considering the effect of real variable amplitude.Using the FVA-LiNGAM causal index,the causal relationship of operation variables can be investigated with higher spatiotemporal accuracy than that of the original LiNGAM index.Taking a real SCADA data subset of a provincial power system as an example,the validity of the FVA-LiNGAM causal index is verified.The variation patterns in spatiotemporal causality are explored using actual SCADA data sequences.The result shows that there indeed exists some spatiotemporal causality variation patterns between the operating variables of the power system.
文摘Life in desert ecosystems drives animals to adapt their surface locomotor activity according to environmental conditions. In this study, the hourly and monthly variations in the surface activity patterns of the terrestrial crustacean Hemilepistus reaumurii were investigated. The surface activity of H. reaumurii at the population scale was observed by collecting the hourly active individuals from the sunrise to the sunset of the studied day in each month of 2013 in the Bchachma locality, Tunisia. The collected active individuals were put in perspex boxes（on which we labeled the hourly time interval in which the individuals were collected） in the field and then transported to the laboratory for analysis. Individuals were counted, sexed, and measured in the laboratory. Despite desert conditions in the studied site, H. reaumurii was characterized by a diurnal surface activity, showing a bimodal pattern during the warm months（i.e., May to October）. However, it exhibited a unimodal surface activity pattern in the cold months（i.e., February, March, and November）. The surface activity was significantly correlated with sunrise and sunset. Moreover, a significant quadratic effect of temperature on the surface activity of H. reaumurii was observed. Furthermore, the study showed that the most important surface activity was recorded in March. The daily exploitation of the temporal niches was significantly different as a function of months. The body size of males was larger than that of females, and the body size of active individuals changed with months. All these behavioural changes in the surface activity represent an adaptive strategy of life in the arid environment.
文摘Dear Editor,We have read and reviewed the article entitled＂The diurnal variation pattern of choroidal thickness in macular region of young healthy female individuals using spectral domain optical coherence tomography＂by Zhao et al^（[1]）with great interest.
文摘The TEEOF method that expands temporally is used to conduct a diagnostic study of the variation patterns of 1, 3, 6 and 10 years with regard to mean air temperature over the globe and Southern and Northern Hemispheres over the course of 100 years. The results show that the first mode of TEEOF takes up more than 50% in the total variance, with each of the first mode in the interannual oscillations generally standing for annually varying patterns which are related with climate and reflecting long-term tendency of change in air temperature. It is particularly true for the first mode on the 10-year scale, which shows an obvious ascending trend concerning the temperature in winter and consistently the primary component of time goes in a way that is very close to the sequence of actual temperature. Apart from the first mode of all time sections of TEEOF for the globe and the two hemispheres and the second mode of the 1-year TEEOF, interannual variation described by other characteristic vectors are showing various patterns, with corresponding primary components having relation with long-term variability of specific interannual quasi-periodic oscillation structures. A 2T test applied to the annual variation pattern shows that the abrupt changes for the Southern Hemisphere and the globe come closer to the result of a uni-element t test for mean temperature than those for the Northern Hemisphere do. It indicates that the 2Ttest, when carried out with patterns of multiple variables, seems more reasonable than the t test with single elements.
文摘Variations of wood specific gravity and extractive contents from pith to bark and from base to the top of tree were investigated in a 14-year-old commercial pulpwood species Sterculia setigera Del. Growing in savanna zone in Nigeria. Tree mean specific gravity averaged 0.37; wood at the base had significant higher specific gravity than those at the top while it increased from pith to bark. For extractive content mean value was 1.20% for wood and 1.72% for bark; i[t varied significantly between trees and from base of the tree to the top and from pith to the bark. Extractive content at the butt and breast height is more than double of the value at the top of the tree. The high extractive content at the base is similar to high specific gravity observed for wood samples from the base. Extractive content of the bast was significantly higher than that of the wood. The low specific gravity show possible suitability of the species for paper making in Nigerian paper mills. The wood of Sterculia setigera showed a significant variation between- and within-trees in the two properties considered, though the wood is light with low extractive content; it is however a potential raw material for large scale pulpwood production in Nigeria.
文摘Instrument neutron activation analysis (INAA) has been employed in this study to determine 32 elements in soil on the loess plateau. The preliminary results suggest that geochemical characteristics of elements in the soil mainly retained those in the parent materials (loess). It has been found that fractional deposition among grain sizes in the process of loess transportation as well as the bioclimate in which the soil developed are main factors affecting the regional variations of elemental distribution in soil on the plateau. Contour maps of element concentrations plotted from the trend analyses exhibit the major patterns of the distributions and variations on the plateau. Furthermore, the study also provides evidence for the aeolian theory of the loess transportation in China.
文摘Subject Code:C01The United Nations estimates that world population will increase to 11.2billion in the year 2100.Vegetative oil that serves as one of the major energy resources is essential to feeding human beings.Oil palm(Elaeis guineensis Jacq,Elaeis from ancient Greek,meaning'oil')produces more than 13times the yield of oil/year/hectare of soybean,one major human annual oil crop.In consequence,it represents a
文摘By means of simulation experiments with a two-dimensional zonal-mean model,a study is made of the influence of the western North-Pacific midlatitude sea-surface temperature(SST)anomalies on the circulation pattern and wet-seasonal precipitation over the East-China Changjiang-Huaihe reaches and the North-China plain.The SST anomalies are divided into two types,one being“colder in the south and warmer in the north”and the other just opposite,depending on season.Results show that the occurrence of the anomalies is followed by considerable changes in the position of the subtropical high happening for 3-5 months to come.For instance,the spring“colder in the south and warmer in the north”anomalous type (i.e.,colder for 20—35°N,and warmer north of 35°N)leads to the intensification of the summer subtropical high,with the ridge line moved slightly northward,resulting in drought over Changjiang reaches for July-August and in excessive rainfall in the North-China plain,and vice versa.
基金financiallysupported by the National Key&Program of China(Grant No.2022YFC3003403)the National Natural Science Foundation of China(Grant Nos.42472348 and 42220104005).
文摘The accelerated demand for engineering services has led to the extensive utilization of engineering blasting techniques.Blasting-induced changes in loess microstructure(e.g.particle breakage,pore structure change)directly affect its macroscopic mechanical properties.However,there remains a notable lack of studies on the impact of explosions on loess microstructure and the quantificationof loess microstructure.This study employed micro-computed tomography(μ-CT)technology to examine loess samples extracted from the surrounding area of the explosion cavity,systematically investigating the volume,orientation,and morphological characteristics of particles and pores.The research findings indicated that the explosion caused a break for the particles with a diameter larger than 10μm,and the number of smaller particles increased.Blasting decreased the particle sphericity and orientation angle.The reduction in porosity was primarily attributed to a decrease in the volume of both macropores and mesopores,with a greater reduction in the volume of mesopores.Although the number of micropores increased,the volume change was insignificant.Furthermore,the explosion increased the pore fractal dimension and patch density,suggesting a more complex and fragmented pore structure.Moreover,the pore throat radius and channel length decreased with decreasing distance from the explosion cavity(D_(EC)),indicating that the pore's connectivity reduced.The radius of the blasting cavity was approximately 0.35 m.Additionally,the loess zone surrounding the blasting cavity was divided into failure,plastic,and elastic zones using the D_(EC)=0.2 m and 1.2 m as the boundaries.The impacts of the explosion on loess were mainly within the range of D_(EC)less than 1.20 m.The analysis of the traits,patterns,and mechanisms of explosions'impact on the loess's microstructure can provide microscopic insight into the macro-dynamic behavior,assess the impact of explosions on the surrounding loess,and identify the potential geological hazards triggered by blasting,which offers a theoretical foundation for the subsequent engineering design and security measures.
文摘Microfibril angle （MFA） in Chinese fir was tested by X-ray diffraction apparatus and calculated by computer software. The results were as follows： MFA was controlled strongly by inheritance, and there was no significant difference in MFA among interspecies, juvenile and mature wood. In the longitudinal, MFA reduces with the height rising from 0 to 5.5 m, especially in the heights from 0 to 1.5 m. The values of MFA are nearly consistence from 1.5 to 7.5 m. The variation range was between 10.82°and 12.57°from 1.5 to 7.5 m, R2 of power equation achieved 0.932 1, and analysis of variance indicated that the variation of MFA was not significant from 1.5 to 7.5 m, The age of the trees had an important influence on MFA, consequently, the difference in MFA was significant among annual rings in radial, which was maximal in near pith and reduced rapidly from the pith to sapwood, and its decline tendency was slow beyond the ninth annual ring. MFA reached minimum value at the 15th annual ring, and the difference reached more than 20° and R^2 of binomial equation achieved 0.755 6.
