On the Loess Plateau, water is the main limiting factors for vegetation growth. Root distribution characters have special ecological meaning as it reflected the utilizations of trees to the environments. Even-aged sta...On the Loess Plateau, water is the main limiting factors for vegetation growth. Root distribution characters have special ecological meaning as it reflected the utilizations of trees to the environments. Even-aged stands ofRobinia pseudoacacia on slope lands facing south and north were selected as sampling plots for root distribution investigation. Investigatiing results showed that indicated that on all sites, root biomass decreased with depth, and the distribution depth of fine root was deeper than that of coarser root. The results of variance analysis indicated that there were great differences in root biomass among different diameter classes, and coarser root was the main sources of variance, and the root biomass, especially fine root (?<3mm) biomass on northern exposition sites was bigger than that on southern exposition sites. Analysis of the vertical root distribution parameters, root extinction coefficient, β indicated that the value of β on northern exposition was more than 0.982, while the value of β on southern exposition was less than 0.982, which indicated that the vertical root distribution depth ofRobinia pseudoacacia on southern exposition was deeper than that on southern exposition. And the distribution depth of fine roots (Φ<1mm) was deeper than that of thicker roots(Φ<3mm), which was in favor of the uptake of water and nutrients from deeper layers, helped the trees to adapt the arid environment, and promoted the growth of the upper parts of the tree. Keywords Root diameter classes - Variance analysis - Root extinction coefficient - Vertical distribution characters - Site conditions - Loess Plateau CLC number S792.27.01 Document code A Foundation Item: This research was supported by National Natural Science Foundation of China (30371150 and 40371075).Biography: LI Peng (1974-) male, post: Ph. D. in Northwest Scientific & Technological University of Agriculture and Forestry, Yangling 712100, Shaanxi Province, P. R. China. Tel: 029-82312651.Responsible editor: Chai Ruihal展开更多
Here we report iron(Fe) isotopic data of three pure Fe solution standards(IRMM-014, GSB Fe, and NIST3126a) and five widely used geological reference materials(RMs) from the United States Geological Survey and Geologic...Here we report iron(Fe) isotopic data of three pure Fe solution standards(IRMM-014, GSB Fe, and NIST3126a) and five widely used geological reference materials(RMs) from the United States Geological Survey and Geological Survey of Japan obtained on a Neptune Plus multi-collector–inductively coupled plasma–mass spectrometer(MC-ICP-MS) in our laboratory over the past 3 years. The instrumental mass bias was corrected by three independent methods: sample-standard bracketing(SSB),Ni doping + SSB, and ^(57)Fe–^(58)Fe double spike + SSB.Measurements reveal that both the Ni doping and double spike methods helped calibrate short-term fluctuations in mass bias. Collectively, almost all measurements of RMs yielded δ^(56)Fe within ± 0.05 of recommended values,provided that each sample was measured four times on MC-ICP-MS. For the first time, new recommended values for NIST SRM3126a are reported(δ^(56)Fe = 0.363 ± 0.006,2SE, 95% CI; and δ^(57)Fe = 0.534 ± 0.010, 2SE).展开更多
Based on the local legislation of marine fishery management, this paper takes the process of local legislation of marine fishery management in Liaoning Province as the main object of study, to explore the advantages a...Based on the local legislation of marine fishery management, this paper takes the process of local legislation of marine fishery management in Liaoning Province as the main object of study, to explore the advantages and existing problems of the process of local marine fishery management. From the perspective of theory and practice, this paper analyzes the local legislative process deeply and discloses some problems, especially analyzes the main steps deeply in order to discover problems in the whole process from drafting to acting and proposes the corresponding solutions.展开更多
Single-phase low current grounding faults areoften seen in power distribution system of coal mines.These faults are difficult to reliably identify.We propose a new method of single-phase ground fault protection based ...Single-phase low current grounding faults areoften seen in power distribution system of coal mines.These faults are difficult to reliably identify.We propose a new method of single-phase ground fault protection based upon a discernible matrix of the fractal dimension associated with line currents.The method builds on existing selective protection methods.Faulted feeders are distinguished using differences in the zero-sequence transient current fractal dimension.The current signals were first processed through a fast Fourier transform and then the characteristics of a faulted line were identified using a discernible matrix.The method of calculation is illustrated.The results show that the method involves simple calculations, is easy to do and is highly accurate.It is, therefore, suitable for distribution networks having different neutral grounding modes.展开更多
Farming is still an important sector in rural economic development of West Virginia where 44% of the population lives in rural areas and 24% of the land is used for farming. While income earnings, education and employ...Farming is still an important sector in rural economic development of West Virginia where 44% of the population lives in rural areas and 24% of the land is used for farming. While income earnings, education and employment rates are low in rural areas, poverty rates and unemployment are high compared to the urban areas. Thus, in the context of rural development farming is a potential major economic sector where 42% of the people＇s primary occupation is reported as farming. The objective of this study is to identify and estimate the potential impacts of farm employment in rural economic growth of West Virginia. Data from U.S. Bureau of Labor Statistics and U.S Census Bureau for the period of 1993 to 2008 are used for the empirical analysis. A model derived from the three simultaneous equations of Duncan is used for analysis. Three-Stage Least Squares （3SLS） method using the statistical package of STATA is used for estimation. The results concerning simultaneous relationships with population density growth, per capita income growth, and farm employment growth reveal significant importance of farming in rural economic development of West Virginia. Furthermore, the results indicate the positive impacts of population density, number of people with farming as principal occupation, and crop production on rural farming sector.展开更多
The effect of topography on generation of the solitary Rossby waves is researched. Here, the topography, as a forcing for waves generation, is taken as a function of longitude variable x and time variable t, which is ...The effect of topography on generation of the solitary Rossby waves is researched. Here, the topography, as a forcing for waves generation, is taken as a function of longitude variable x and time variable t, which is called unstable topography. With the help of a perturbation expansion method, a forced mKdv equation governing the evolution of amplitude of the solitary Rossby waves is derived from quasi-geostrophic vortieity equation and is solved by the pseudo-spectral method. Basing on the waterfall plots, the generational features of the solitary Rossby waves under the influence of unstable topography and stable topography are compared and some conclusions are obtained.展开更多
基金This research was supported by National Natural Science Foundation of China (30371150 and 40371075).
文摘On the Loess Plateau, water is the main limiting factors for vegetation growth. Root distribution characters have special ecological meaning as it reflected the utilizations of trees to the environments. Even-aged stands ofRobinia pseudoacacia on slope lands facing south and north were selected as sampling plots for root distribution investigation. Investigatiing results showed that indicated that on all sites, root biomass decreased with depth, and the distribution depth of fine root was deeper than that of coarser root. The results of variance analysis indicated that there were great differences in root biomass among different diameter classes, and coarser root was the main sources of variance, and the root biomass, especially fine root (?<3mm) biomass on northern exposition sites was bigger than that on southern exposition sites. Analysis of the vertical root distribution parameters, root extinction coefficient, β indicated that the value of β on northern exposition was more than 0.982, while the value of β on southern exposition was less than 0.982, which indicated that the vertical root distribution depth ofRobinia pseudoacacia on southern exposition was deeper than that on southern exposition. And the distribution depth of fine roots (Φ<1mm) was deeper than that of thicker roots(Φ<3mm), which was in favor of the uptake of water and nutrients from deeper layers, helped the trees to adapt the arid environment, and promoted the growth of the upper parts of the tree. Keywords Root diameter classes - Variance analysis - Root extinction coefficient - Vertical distribution characters - Site conditions - Loess Plateau CLC number S792.27.01 Document code A Foundation Item: This research was supported by National Natural Science Foundation of China (30371150 and 40371075).Biography: LI Peng (1974-) male, post: Ph. D. in Northwest Scientific & Technological University of Agriculture and Forestry, Yangling 712100, Shaanxi Province, P. R. China. Tel: 029-82312651.Responsible editor: Chai Ruihal
基金supported by the National Natural Science Foundation of China(41473016)the State Key Laboratory of Geological Processes and Mineral Resources
文摘Here we report iron(Fe) isotopic data of three pure Fe solution standards(IRMM-014, GSB Fe, and NIST3126a) and five widely used geological reference materials(RMs) from the United States Geological Survey and Geological Survey of Japan obtained on a Neptune Plus multi-collector–inductively coupled plasma–mass spectrometer(MC-ICP-MS) in our laboratory over the past 3 years. The instrumental mass bias was corrected by three independent methods: sample-standard bracketing(SSB),Ni doping + SSB, and ^(57)Fe–^(58)Fe double spike + SSB.Measurements reveal that both the Ni doping and double spike methods helped calibrate short-term fluctuations in mass bias. Collectively, almost all measurements of RMs yielded δ^(56)Fe within ± 0.05 of recommended values,provided that each sample was measured four times on MC-ICP-MS. For the first time, new recommended values for NIST SRM3126a are reported(δ^(56)Fe = 0.363 ± 0.006,2SE, 95% CI; and δ^(57)Fe = 0.534 ± 0.010, 2SE).
文摘Based on the local legislation of marine fishery management, this paper takes the process of local legislation of marine fishery management in Liaoning Province as the main object of study, to explore the advantages and existing problems of the process of local marine fishery management. From the perspective of theory and practice, this paper analyzes the local legislative process deeply and discloses some problems, especially analyzes the main steps deeply in order to discover problems in the whole process from drafting to acting and proposes the corresponding solutions.
基金Project 50504015 supported by the National Natural Science Foundation of Chinathe Youth Science and Technology Research Program of China University of Mining and Technology (0C060996)
文摘Single-phase low current grounding faults areoften seen in power distribution system of coal mines.These faults are difficult to reliably identify.We propose a new method of single-phase ground fault protection based upon a discernible matrix of the fractal dimension associated with line currents.The method builds on existing selective protection methods.Faulted feeders are distinguished using differences in the zero-sequence transient current fractal dimension.The current signals were first processed through a fast Fourier transform and then the characteristics of a faulted line were identified using a discernible matrix.The method of calculation is illustrated.The results show that the method involves simple calculations, is easy to do and is highly accurate.It is, therefore, suitable for distribution networks having different neutral grounding modes.
文摘Farming is still an important sector in rural economic development of West Virginia where 44% of the population lives in rural areas and 24% of the land is used for farming. While income earnings, education and employment rates are low in rural areas, poverty rates and unemployment are high compared to the urban areas. Thus, in the context of rural development farming is a potential major economic sector where 42% of the people＇s primary occupation is reported as farming. The objective of this study is to identify and estimate the potential impacts of farm employment in rural economic growth of West Virginia. Data from U.S. Bureau of Labor Statistics and U.S Census Bureau for the period of 1993 to 2008 are used for the empirical analysis. A model derived from the three simultaneous equations of Duncan is used for analysis. Three-Stage Least Squares （3SLS） method using the statistical package of STATA is used for estimation. The results concerning simultaneous relationships with population density growth, per capita income growth, and farm employment growth reveal significant importance of farming in rural economic development of West Virginia. Furthermore, the results indicate the positive impacts of population density, number of people with farming as principal occupation, and crop production on rural farming sector.
基金Supported by National Sciences Key Foundation of China under Grant No. 41030855National Natural Science Foundation of China under Grant Nos. 41106017 and 70971079+1 种基金Natural Science Foundation of Jiangsu Province under Grant No. BK2011396National Basic Research Program of China (973) Funded Project under Grant No. 2011CB201206
文摘The effect of topography on generation of the solitary Rossby waves is researched. Here, the topography, as a forcing for waves generation, is taken as a function of longitude variable x and time variable t, which is called unstable topography. With the help of a perturbation expansion method, a forced mKdv equation governing the evolution of amplitude of the solitary Rossby waves is derived from quasi-geostrophic vortieity equation and is solved by the pseudo-spectral method. Basing on the waterfall plots, the generational features of the solitary Rossby waves under the influence of unstable topography and stable topography are compared and some conclusions are obtained.
