Based on the investigation of the status of forest land resources in the southern parts of Cixi City,the problems exiting in the development of forestry(e.g.overdevelopment of industry and decline in water conservatio...Based on the investigation of the status of forest land resources in the southern parts of Cixi City,the problems exiting in the development of forestry(e.g.overdevelopment of industry and decline in water conservation quality)are pointed out,and countermeasures(e.g.coordination,integration,scientific planning,strict protection,orderly development and ecological compensation)are put forward,in order to provide a reference for the sustainable development of forestry in Cixi City.展开更多
Screw connection is a type most commonly applied to timber structures.As important commercial tree species in China,Masson pine and Chinese fir have the potential to prepare wood structures.In this study,the effects o...Screw connection is a type most commonly applied to timber structures.As important commercial tree species in China,Masson pine and Chinese fir have the potential to prepare wood structures.In this study,the effects of the diameter of the self-tapping screw and the guiding bores on the nail holding performance on different sections of Masson pine and Chinese fir dimension lumbers were mainly explored.The results showed that:(1)The nail holding strength of the tangential section was the maximum,followed by that of the radial section,and that of the cross section was the minimum.(2)The nail holding strength of Masson pine was higher than that of Chinese fir.(3)The nail holding strength grew with the increase in the diameter of self-tapping screws,but a large diameter would lead to plastic cracking of the timber,thus further affecting the nail holding strength.Masson pine and Chinese fir reached the maximum nail holding strength when the diameter of self-tapping screws was 3.5 mm.(4)Under a large diameter of screws,prefabricated guiding bores could mitigate timber cracking and improve its nail holding strength.(5)Prefabricated guiding bores were more necessary for the screw connection of Masson pine.The results obtained could provide a scientific basis for the screw connection design of Masson pine and Chinese fir timber structures.展开更多
As China’s economy shifts from high-speed development to high-quality development,China’s urbanization also shifts from incremental expansion to stock optimization,providing a new direction for the transformation of...As China’s economy shifts from high-speed development to high-quality development,China’s urbanization also shifts from incremental expansion to stock optimization,providing a new direction for the transformation of urban villages.At present,the reconstruction work office of urban villages in small towns is mainly promoted based on government-led and villager main body in the initial exploration stage.From the perspective of policy orientation,to solve the main problems in urban villages in small towns,Zhuangqian Xiongjia Village,Fengcheng City was taken as an example,and the micro-transformation strategies of urban villages were put forward from the perspective of satisfying the appeals of the government,village committee and villagers,so as to provide some references for the transformation of urban villages in other small towns across the country.展开更多
Heat flux is important for studying interactions between atmosphere and lake.The heat exchange between air-water interfaces is one of the important ways to govern the temperature of the water surface.Heat exchange bet...Heat flux is important for studying interactions between atmosphere and lake.The heat exchange between air-water interfaces is one of the important ways to govern the temperature of the water surface.Heat exchange between the air-water interfaces and the surrounding environment is completed by solar radiation,conduction,and evaporation,and all these processes mainly occur at the air-water interface.Hulun Lake was the biggest lake which is also an important link and an indispensable part of the water cycle in Northeast China.This study mapped surface energy budget to better understand spatial and temporal variations in Hulun Lake in China from 2001 to 2018.Descriptive statistics were computed to build a historical time series of mean monthly heat flux at daytime and nighttime from June to September during 2001–2018.Remote sensing estimation methods we used was suitable for Hulun Lake(R2=0.81).At month scale,shortwave radiation and latent heat flux were decrease from June to September.However,the maximum sensible heat flux appeared in September.Net longwave radiation was the largest in August.The effective heat budget showed that Hulun Lake gained heat in the frost-free season with highest value in June(686.31 W/m2),and then steadily decreased to September(439.76 W/m2).At annual scale,net longwave radiation,sensible heat flux and latent heat flux all show significant growth trend from 2001 to 2018(P<0.01).Wind speed had the well correlation on sensible heat flux and latent heat flux.Water surface temperature showed the highest coefficient in sensitivity analysis.展开更多
The South Narimalahei area is located on the north side of the Middle Kunlun fault in the eastern section of the East Kunlun composite orogenic belt. The ore body is veined and controlled by structures and se- condary...The South Narimalahei area is located on the north side of the Middle Kunlun fault in the eastern section of the East Kunlun composite orogenic belt. The ore body is veined and controlled by structures and se- condary fissures, which occurs in the structural alteration fracture zone in the Late Triassic granodiorite. In this deposit, copper mineralization is closely related to silicification and sericification. The formation process of the deposit includes hydrothermal mineralization and supergene oxidation. In this paper, the fluid inclusion minera- logy , microscopic temperature measurement and stable isotope studies have been carried out for ore of the main mineralization stage. The results show that the primary gas-liquid two-phase inclusions and a small amount of single-liquid inclusions are mainly developed in the quartz in the main mineralization stage. The results of microscopic temperature measurement show that the ore-forming fluid which has low temperature (151.7℃ -205.8 ℃), low salinity(2.06wt% - 4.94wt%NaCl), low density (0.86 -0.92 g/cm^( 3)) and shallow formation (1.5 -3.0 km) is a hydrothermal solution of NaCl-H_(2)O system. Hydrogen and oxygen isotope results show that the ore-forming fluids mainly come from atmospheric precipitation, with a small amount of magmatic fluids participating. It is preliminarily determined that the South Narimalahei copper polymetallic deposit is a low- temperature hydrothermal vein deposit.展开更多
The low-pass fi ltering eff ect of the Earth results in the absorption and attenuation of the high-frequency components of seismic signals by the stratum during propagation.Hence,seismic data have low resolution.Consi...The low-pass fi ltering eff ect of the Earth results in the absorption and attenuation of the high-frequency components of seismic signals by the stratum during propagation.Hence,seismic data have low resolution.Considering the limitations of traditional high-frequency compensation methods,this paper presents a new method based on adaptive generalized S transform.This method is based on the study of frequency spectrum attenuation law of seismic signals,and the Gauss window function of adaptive generalized S transform is used to fi t the attenuation trend of seismic signals to seek the optimal Gauss window function.The amplitude spectrum compensation function constructed using the optimal Gauss window function is used to modify the time-frequency spectrum of the adaptive generalized S transform of seismic signals and reconstruct seismic signals to compensate for high-frequency attenuation.Practical data processing results show that the method can compensate for the high-frequency components that are absorbed and attenuated by the stratum,thereby eff ectively improving the resolution and quality of seismic data.展开更多
In the present study, the Karun River in Khuzestan province in Iran is that is somehow considered the river with the most water in the country was examined. To examine the depth and speed of the flow, which undoubtedl...In the present study, the Karun River in Khuzestan province in Iran is that is somehow considered the river with the most water in the country was examined. To examine the depth and speed of the flow, which undoubtedly have the greatest impact on the environment and ecosystem of the river, two-dimensional simulation by CCHE2D model was used. In this study, it was observed that, firstly, the changes of depth and velocity along the river have good coordination and the highest changes were observed in the meander and arches. Moreover, due to using two-dimensional model, there is the possibility of examining changes of parameters in the longitudinal and transverse direction that shows the two-dimensional model is an efficient and powerful model in studying river flows.展开更多
[Objectives]This study was conducted to investigate the effect of different planting patterns on soil improvement in rocky desertification areas.[Methods]The one-way ANOVA analysis method was used to statistically ana...[Objectives]This study was conducted to investigate the effect of different planting patterns on soil improvement in rocky desertification areas.[Methods]The one-way ANOVA analysis method was used to statistically analyze the soil physical and chemical properties,enzyme activity,microbial quantity,CEC,ECEC,and aggregate content distribution with different planting patterns.[Results]The walnut+sesame+mung bean planting pattern showed the highest soil available phosphorus,available potassium,porosity,non-capillary porosity,and contents of free living nitrogen-fixing bacteria,organophosphate-dissolving bacteria,bacteria,fungi and actinomycetes,at 63.2 mg/kg,178.8 mg/kg,22.85%,6.89%,10.0×10^6 bacteria/g,18.0×10^6 bacteria/g,21.0×10^5 CFU/g,5.7×10^3 CFU/g and 7.9×10^5 CFU/g,respectively,and it reduced soil bulk density(the same as treatment F and treatment E)compared with other planting patterns.The walnut+American chicory+sweet potato planting pattern had the highest alkali-hydrolyzale nitrogen,organic matter,CEC,ECEC,water-air ratio and moisture content,which were 227.9 mg/kg,46.30 g/kg,36.38 cmol/kg,24.00 cmol/kg,8.13,and 32.89%,respectively,and it reduced soil bulk density,increased capillary porosity,acid phosphatase,and contents of bacteria and actinomycetes compared with single cropping of walnut.[Conclusions]Interplanting crops under walnut forests is an effective measure to improve the ecological environment of rocky desertification farmland.展开更多
Freeze-thaw erosion can lead to accelerated soil loss,which is an important factor related to soil erosion in cold regions.Tibet is a typical region that is seriously affected by freeze-thaw erosion.Traditionally,the ...Freeze-thaw erosion can lead to accelerated soil loss,which is an important factor related to soil erosion in cold regions.Tibet is a typical region that is seriously affected by freeze-thaw erosion.Traditionally,the analytic hierarchy process(AHP)method is used to calculate the weight of the factors in evaluations of freeze-thaw erosion,but this method cannot accurately depict the fuzziness and randomness of the problem.To overcome this disadvantage,this study proposed an improved AHP method based on the cloud model for the evaluation of the factors impacting freeze-thaw erosion.To establish an improved evaluation method for freeze-thaw erosion in Tibet,the following six factors were selected:mean annual air temperature,mean annual ground surface temperature,average annual precipitation,aspect,vegetation coverage,and topographic relief.The traditional AHP and the cloud model were combined to assign the weights of the impacting factors,and a consistency check was performed.The comprehensive evaluation index model was used to evaluate the intensity of freeze-thaw erosion in Tibet.The results show that freeze-thaw erosion is extensive,stretching over approximately 66.1%of Tibet.Moreover,mild erosion and moderate erosion are the most widely distributed erosion intensity levels,accounting for 36.4%and 34.4%of the total freeze-thaw erosion,respectively.The intensity of freeze-thaw erosion gradually increased from slight erosion in the northwest to severe erosion in the southeast of the study region.The evaluation results for the intensity and distribution of freeze-thaw erosion in Tibet were confirmed to be consistent with the actual situation.In brief,this study supplies a new approach for quantitatively evaluating the intensity of freeze-thaw erosion in Tibet.展开更多
Better understanding the determining factors of dynamic magnetic relaxation in polynuclear lanthanide based single-molecule magnets(SMMs)remains a challenge due to the complexity of such architectures involving intera...Better understanding the determining factors of dynamic magnetic relaxation in polynuclear lanthanide based single-molecule magnets(SMMs)remains a challenge due to the complexity of such architectures involving interactions between the magnetic centers.To address this issue,two structurally related heterometal Dy^(III)_(2)Zn^(II)_(2) SMMs,[Zn_(2)Dy_(2)(L)_(4)(Ac)_(2)(DMF)(CH_(3)OH)]·CH_(3)OH·2H_(2)O(1)and[Zn_(2)Dy_(2)(L)_(4)(Ac)_(2)(DMF)_(2)]·4CH_(3)CN(2)(H_(2)L=(E)-2-((2-hydroxy-3-methoxybenzylidene)amino)-4-methyphenol,DMF=N,N-dimethylformamide),are introduced and investigated.Through modifying the auxiliary ligands on one Dy^(III) site while retaining that on the other Dy^(III),the intramolecular magnetic interactions and relaxation dynamics in these two heterometallic-Dy^(III)_(2)Zn^(II)_(2) SMMs can be tuned,demonstrating a dramatic change in the magnet relaxation behavior with energy barrier changing from a negligible value for 1 to 305 K for 2.Ab initio calculations reveal that changing the coordination geometries on the Dy^(III) sites can significantly affect the magnetic interactions as well as single-ion anisotropy.展开更多
文摘Based on the investigation of the status of forest land resources in the southern parts of Cixi City,the problems exiting in the development of forestry(e.g.overdevelopment of industry and decline in water conservation quality)are pointed out,and countermeasures(e.g.coordination,integration,scientific planning,strict protection,orderly development and ecological compensation)are put forward,in order to provide a reference for the sustainable development of forestry in Cixi City.
基金funded by the National Natural Science Foundation of China (32160348)Forestry Science and Technology Research Project of Guizhou Forestry Bureau (J[2022]21 and[2020]C14)+1 种基金Department Program of Guizhou Province ([2020]1Y128)the Cultivation Project of Guizhou University of China ([2019]37).
文摘Screw connection is a type most commonly applied to timber structures.As important commercial tree species in China,Masson pine and Chinese fir have the potential to prepare wood structures.In this study,the effects of the diameter of the self-tapping screw and the guiding bores on the nail holding performance on different sections of Masson pine and Chinese fir dimension lumbers were mainly explored.The results showed that:(1)The nail holding strength of the tangential section was the maximum,followed by that of the radial section,and that of the cross section was the minimum.(2)The nail holding strength of Masson pine was higher than that of Chinese fir.(3)The nail holding strength grew with the increase in the diameter of self-tapping screws,but a large diameter would lead to plastic cracking of the timber,thus further affecting the nail holding strength.Masson pine and Chinese fir reached the maximum nail holding strength when the diameter of self-tapping screws was 3.5 mm.(4)Under a large diameter of screws,prefabricated guiding bores could mitigate timber cracking and improve its nail holding strength.(5)Prefabricated guiding bores were more necessary for the screw connection of Masson pine.The results obtained could provide a scientific basis for the screw connection design of Masson pine and Chinese fir timber structures.
文摘As China’s economy shifts from high-speed development to high-quality development,China’s urbanization also shifts from incremental expansion to stock optimization,providing a new direction for the transformation of urban villages.At present,the reconstruction work office of urban villages in small towns is mainly promoted based on government-led and villager main body in the initial exploration stage.From the perspective of policy orientation,to solve the main problems in urban villages in small towns,Zhuangqian Xiongjia Village,Fengcheng City was taken as an example,and the micro-transformation strategies of urban villages were put forward from the perspective of satisfying the appeals of the government,village committee and villagers,so as to provide some references for the transformation of urban villages in other small towns across the country.
基金Under the auspices of National Key Research and Development Program of China(No.2016YFA0602301,2016YFB0501502)Strategic Planning Project of the Northeast Institute of Geography and Agroecology(IGA),Chinese Academy of Sciences(No.Y6H2091001)National Forestry Science and Technology Demonstration Promotion Project(No.JLT2018-03)。
文摘Heat flux is important for studying interactions between atmosphere and lake.The heat exchange between air-water interfaces is one of the important ways to govern the temperature of the water surface.Heat exchange between the air-water interfaces and the surrounding environment is completed by solar radiation,conduction,and evaporation,and all these processes mainly occur at the air-water interface.Hulun Lake was the biggest lake which is also an important link and an indispensable part of the water cycle in Northeast China.This study mapped surface energy budget to better understand spatial and temporal variations in Hulun Lake in China from 2001 to 2018.Descriptive statistics were computed to build a historical time series of mean monthly heat flux at daytime and nighttime from June to September during 2001–2018.Remote sensing estimation methods we used was suitable for Hulun Lake(R2=0.81).At month scale,shortwave radiation and latent heat flux were decrease from June to September.However,the maximum sensible heat flux appeared in September.Net longwave radiation was the largest in August.The effective heat budget showed that Hulun Lake gained heat in the frost-free season with highest value in June(686.31 W/m2),and then steadily decreased to September(439.76 W/m2).At annual scale,net longwave radiation,sensible heat flux and latent heat flux all show significant growth trend from 2001 to 2018(P<0.01).Wind speed had the well correlation on sensible heat flux and latent heat flux.Water surface temperature showed the highest coefficient in sensitivity analysis.
文摘The South Narimalahei area is located on the north side of the Middle Kunlun fault in the eastern section of the East Kunlun composite orogenic belt. The ore body is veined and controlled by structures and se- condary fissures, which occurs in the structural alteration fracture zone in the Late Triassic granodiorite. In this deposit, copper mineralization is closely related to silicification and sericification. The formation process of the deposit includes hydrothermal mineralization and supergene oxidation. In this paper, the fluid inclusion minera- logy , microscopic temperature measurement and stable isotope studies have been carried out for ore of the main mineralization stage. The results show that the primary gas-liquid two-phase inclusions and a small amount of single-liquid inclusions are mainly developed in the quartz in the main mineralization stage. The results of microscopic temperature measurement show that the ore-forming fluid which has low temperature (151.7℃ -205.8 ℃), low salinity(2.06wt% - 4.94wt%NaCl), low density (0.86 -0.92 g/cm^( 3)) and shallow formation (1.5 -3.0 km) is a hydrothermal solution of NaCl-H_(2)O system. Hydrogen and oxygen isotope results show that the ore-forming fluids mainly come from atmospheric precipitation, with a small amount of magmatic fluids participating. It is preliminarily determined that the South Narimalahei copper polymetallic deposit is a low- temperature hydrothermal vein deposit.
基金This research is supported by the National Science and Technology Major Project of China(No.2011ZX05024-001-03)the Natural Science Basic Research Plan in Shaanxi Province of China(No.2021JQ-588)Innovation Fund for graduate students of Xi’an Shiyou University(No.YCS17111017).
文摘The low-pass fi ltering eff ect of the Earth results in the absorption and attenuation of the high-frequency components of seismic signals by the stratum during propagation.Hence,seismic data have low resolution.Considering the limitations of traditional high-frequency compensation methods,this paper presents a new method based on adaptive generalized S transform.This method is based on the study of frequency spectrum attenuation law of seismic signals,and the Gauss window function of adaptive generalized S transform is used to fi t the attenuation trend of seismic signals to seek the optimal Gauss window function.The amplitude spectrum compensation function constructed using the optimal Gauss window function is used to modify the time-frequency spectrum of the adaptive generalized S transform of seismic signals and reconstruct seismic signals to compensate for high-frequency attenuation.Practical data processing results show that the method can compensate for the high-frequency components that are absorbed and attenuated by the stratum,thereby eff ectively improving the resolution and quality of seismic data.
文摘In the present study, the Karun River in Khuzestan province in Iran is that is somehow considered the river with the most water in the country was examined. To examine the depth and speed of the flow, which undoubtedly have the greatest impact on the environment and ecosystem of the river, two-dimensional simulation by CCHE2D model was used. In this study, it was observed that, firstly, the changes of depth and velocity along the river have good coordination and the highest changes were observed in the meander and arches. Moreover, due to using two-dimensional model, there is the possibility of examining changes of parameters in the longitudinal and transverse direction that shows the two-dimensional model is an efficient and powerful model in studying river flows.
基金Guangxi Innovation-driven Development Project(GK AA17204058-16)Guangxi Science and Technology Planning Project(GKG 1598016-13)Basic Scientific and Research Program of Guangxi Academy of Agricultural Sciences(GNK 2021YT041,GNK 2019ZX126)。
文摘[Objectives]This study was conducted to investigate the effect of different planting patterns on soil improvement in rocky desertification areas.[Methods]The one-way ANOVA analysis method was used to statistically analyze the soil physical and chemical properties,enzyme activity,microbial quantity,CEC,ECEC,and aggregate content distribution with different planting patterns.[Results]The walnut+sesame+mung bean planting pattern showed the highest soil available phosphorus,available potassium,porosity,non-capillary porosity,and contents of free living nitrogen-fixing bacteria,organophosphate-dissolving bacteria,bacteria,fungi and actinomycetes,at 63.2 mg/kg,178.8 mg/kg,22.85%,6.89%,10.0×10^6 bacteria/g,18.0×10^6 bacteria/g,21.0×10^5 CFU/g,5.7×10^3 CFU/g and 7.9×10^5 CFU/g,respectively,and it reduced soil bulk density(the same as treatment F and treatment E)compared with other planting patterns.The walnut+American chicory+sweet potato planting pattern had the highest alkali-hydrolyzale nitrogen,organic matter,CEC,ECEC,water-air ratio and moisture content,which were 227.9 mg/kg,46.30 g/kg,36.38 cmol/kg,24.00 cmol/kg,8.13,and 32.89%,respectively,and it reduced soil bulk density,increased capillary porosity,acid phosphatase,and contents of bacteria and actinomycetes compared with single cropping of walnut.[Conclusions]Interplanting crops under walnut forests is an effective measure to improve the ecological environment of rocky desertification farmland.
基金funded by the National Key Research and Development Program of China(No.2017YFB0503500)the Shandong Provincial Natural Science Foundation(Nos.ZR2020MD015 and ZR2020MD018)+1 种基金the Guangdong Academy of Sciences to build First-rate Research Institution Special Fund for Action Project(No.2019GDASYL-0103003)the Young Teacher Development Support Program of Shandong University of Technology(No.4072-115016).
文摘Freeze-thaw erosion can lead to accelerated soil loss,which is an important factor related to soil erosion in cold regions.Tibet is a typical region that is seriously affected by freeze-thaw erosion.Traditionally,the analytic hierarchy process(AHP)method is used to calculate the weight of the factors in evaluations of freeze-thaw erosion,but this method cannot accurately depict the fuzziness and randomness of the problem.To overcome this disadvantage,this study proposed an improved AHP method based on the cloud model for the evaluation of the factors impacting freeze-thaw erosion.To establish an improved evaluation method for freeze-thaw erosion in Tibet,the following six factors were selected:mean annual air temperature,mean annual ground surface temperature,average annual precipitation,aspect,vegetation coverage,and topographic relief.The traditional AHP and the cloud model were combined to assign the weights of the impacting factors,and a consistency check was performed.The comprehensive evaluation index model was used to evaluate the intensity of freeze-thaw erosion in Tibet.The results show that freeze-thaw erosion is extensive,stretching over approximately 66.1%of Tibet.Moreover,mild erosion and moderate erosion are the most widely distributed erosion intensity levels,accounting for 36.4%and 34.4%of the total freeze-thaw erosion,respectively.The intensity of freeze-thaw erosion gradually increased from slight erosion in the northwest to severe erosion in the southeast of the study region.The evaluation results for the intensity and distribution of freeze-thaw erosion in Tibet were confirmed to be consistent with the actual situation.In brief,this study supplies a new approach for quantitatively evaluating the intensity of freeze-thaw erosion in Tibet.
基金supported by the National Natural Science Foundation of China(Nos.21971207,21973046)the Natural Science Foundation of Science and Technology Agency of Shanxi Province(No.20210302124654)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(No.2021259).
文摘Better understanding the determining factors of dynamic magnetic relaxation in polynuclear lanthanide based single-molecule magnets(SMMs)remains a challenge due to the complexity of such architectures involving interactions between the magnetic centers.To address this issue,two structurally related heterometal Dy^(III)_(2)Zn^(II)_(2) SMMs,[Zn_(2)Dy_(2)(L)_(4)(Ac)_(2)(DMF)(CH_(3)OH)]·CH_(3)OH·2H_(2)O(1)and[Zn_(2)Dy_(2)(L)_(4)(Ac)_(2)(DMF)_(2)]·4CH_(3)CN(2)(H_(2)L=(E)-2-((2-hydroxy-3-methoxybenzylidene)amino)-4-methyphenol,DMF=N,N-dimethylformamide),are introduced and investigated.Through modifying the auxiliary ligands on one Dy^(III) site while retaining that on the other Dy^(III),the intramolecular magnetic interactions and relaxation dynamics in these two heterometallic-Dy^(III)_(2)Zn^(II)_(2) SMMs can be tuned,demonstrating a dramatic change in the magnet relaxation behavior with energy barrier changing from a negligible value for 1 to 305 K for 2.Ab initio calculations reveal that changing the coordination geometries on the Dy^(III) sites can significantly affect the magnetic interactions as well as single-ion anisotropy.