Permeability of wood preservative is one of the most significant factors for protection of wood construction.Ani-sotropic flow permeability was involved in different directions of wood with higher flow resistance in t...Permeability of wood preservative is one of the most significant factors for protection of wood construction.Ani-sotropic flow permeability was involved in different directions of wood with higher flow resistance in the trans-verse and lower longitudinal directions.In this study,boron acid solution was brushed onto the tangential section of air-dried wood cubes and boron penetration along wood transverse direction was investigated under free dif-fusion,vacuum and HVEF treatments.Multi-scale boron distribution,FTIR measurement,leaching property,mechanical properties and fungistatic characteristic were investigated for free diffusion,vacuum and HVEF trea-ted samples respectively.The results revealed that boron exhibited high permeability along the transverse direc-tion with the penetration depth of≈35 mm for HVEF treated samples and≈1 mm for free diffusion and vacuum treated samples.For HVEF treated samples,no significant decrease of hardness,compression modulus of elasti-city and strength were found in the treated samples.Better fungistatic characteristic was showcased in HVEF trea-ted samples exposed to white rot fungi.Thus,HVEF treatment has a positive effect on boron permeability and the improvement of penetration depth of preservatives hence playing a significant role in wood protection and prolonging the service life of wood construction.展开更多
The simplified mechanical model and finite element model are established on the basis of the measured results and analysis of the grouting pile deformation monitoring,surface horizontal displacement and vertical displ...The simplified mechanical model and finite element model are established on the basis of the measured results and analysis of the grouting pile deformation monitoring,surface horizontal displacement and vertical displacement monitoring,deep horizontal displacement(inclinometer)monitoring,soil pressure monitoring and seepage pressure monitoring in the lower reaches of Wuan River regulation project in Shishi,Fujian Province.The mechanical behavior and deformation performance of mould-bag pile retaining wall formed after controlled cement grouting in the silty stratum of the test section are analyzed and compared.The results show that the use of controlled cement grouting mould-bag pile technology is to strengthen the soft stratum for sealing water and reinforcement,so that it can rock into a retaining wall,which can both retain soil and seal water with excellent effect.The control of cement grouting technology not only makes the soft soil rock in the range of retaining wall of mould-bag pile,but also makes a wide range of soil around the mould-bag pile squeeze and embed to compaction;and its cohesion and internal friction angle increased,so as to achieve the purpose of reducing soil pressure and improving mechanical and deformation properties of retaining wall.展开更多
The genus Eysarcoris can be easily distinguished from other genera through the two spots in the basal angle of the scutellum. Nevertheless, Eysarcoris species show complex variances. Geometric morphometric methods hav...The genus Eysarcoris can be easily distinguished from other genera through the two spots in the basal angle of the scutellum. Nevertheless, Eysarcoris species show complex variances. Geometric morphometric methods have been increasingly applied to distinguish species and to define the boundary of genera among insects. In the present study, geometric morphometric approach was firstly employed to evaluate the shape variation of three characters (fore wing, hind wing and pygophore) of E. guttiger, E. annamita and E. ventralis using E. aeneus as outgroup to ascertain whether this approach is a reliable method for the taxonomy of Eysarcoris. Analysis was conducted on the landmarks of the three characters of these species. Multivariate regression of procrustes coordinates against centroid size was conducted to test the presence of allometry. Principal component analysis (PCA), canonical variate analysis (CVA) and cluster analysis were utilized to describe variations in shapes among the studied species. For all of the three characters, though PCA analysis showed some overlap among species, p-values for procrustes distance and mahalanobis distance were all less than 0.0001. The distribution of the three studied species corresponds with their species status. This study demonstrates that the geometric morphometrics of both the fore wing and the hind wing might represent a possible tool for the identification of species within this genus.展开更多
Photocatalytic water splitting utilizing solar energy is considered as one of the most ideal strategies for solving the ene rgy and environmental issues.Recently,two-dimensional(2 D)materials with an intrinsic dipole ...Photocatalytic water splitting utilizing solar energy is considered as one of the most ideal strategies for solving the ene rgy and environmental issues.Recently,two-dimensional(2 D)materials with an intrinsic dipole show great chance to achieve excellent photocatalytic performance.In this work,blue-phase monolayer carbon monochalcogenides(CX,X=S,Se)are constructed and systematically studied as photocatalysts for water splitting by performing first-principles calculations based on density functional theory.After confirming the great dynamical,thermal,and mechanical stability of CX monolayers,we observe that they possess moderate band gaps(2.41 eV for CS and 2.46 eV for CSe)and high carrier mobility(3.23×10^(4)cm^(2)V^(^(-1))s^(-1)for CS and 4.27×10^(3)cm^(2)V^(-1)s^(-1)for CSe),comparable to those of many recently reported 2 D photocatalysts.Moreover,these two monolayer materials are found to have large intrinsic dipole(0.43 D for CS and 0.51 D for CSe),thus the build-in internal electric field can be selfintroduced,which can effectively drive the separation of photongenerated carriers.More importantly,the well-aligned band edge as well as rather pronounced optical absorption in the visible-light and ultraviolet regions further ensure that our proposed CX monolayers can be used as high efficient photocatalysts for water splitting.Additionally,the effects of external strain on the electronic,optical and photocatalytic properties of CX monolayers are also evaluated.These theoretical predictions will stimulate further work to open up the energy-related applications of CX monolayers.展开更多
The study of nanobubbles (with sizes of the order of tens to hundreds of nanometers) is currently a hot spot of cavitation and bubble dynamics. In the literature, classical formulas are widely employed for the predi...The study of nanobubbles (with sizes of the order of tens to hundreds of nanometers) is currently a hot spot of cavitation and bubble dynamics. In the literature, classical formulas are widely employed for the predictions of the thermal behavior of oscilla- ting macro-bubbles. However, for modelling nanobubbles, the classical formulas may not be adequate due to the effects of the surface tension. In the present paper, a formula with the effects of surface tension fully considered is proposed for the predictions of thermal behavior. The predictions based on the classical formula are also presented for comparisons to show the advantages of the present formula.展开更多
Owing to the part-load operations for the enhancement of grid flexibility, the Francis turbine often suffers from severe low-frequency and large-amplitude hydraulic instability, which is mostly pertinent to the highly...Owing to the part-load operations for the enhancement of grid flexibility, the Francis turbine often suffers from severe low-frequency and large-amplitude hydraulic instability, which is mostly pertinent to the highly unsteady swirling vortex rope in the draft tube. The influence of disturbances in the upstream(e.g., large-scale vortex structures in the spiral casing) on the draft-tube vortex flow is not well understood yet. In the present paper, the influence of the upstream disturbances on the vortical flow in the draft tube is studied based on the vortex identification method and the analysis of several important parameters(e.g., the swirl number and the velocity profile). For a small guide vane opening(representing the part-load condition), the vortices triggered in the spiral casing propagate downstream and significantly affect the swirling vortex-rope precession in the draft tube, leading to the changes of the intensity and the processional frequency of the swirling vortex rope. When the guide vane opening approaches the optimum one(representing the full-load condition), the upstream disturbance becomes weaker and thus its influences on the downstream flow are very limited.展开更多
Further geometric morphometric analysis of the genus Eysarcoris was done based on the former studies to classified the nine Eysarcoris species from China. In this study, six characters, such as forewing, hindwing, pyg...Further geometric morphometric analysis of the genus Eysarcoris was done based on the former studies to classified the nine Eysarcoris species from China. In this study, six characters, such as forewing, hindwing, pygophore, head, pronotum and scutellum, were selected to investigate the shape variation of Eysarcoris. Significant divergence in the shapes of the six characters was observed among the species(p 〈 0.05). For all methods, phenetic similarity based on the six characters agrees with the current status of the genus. The cluster analysis of eight species are consistent with the traditional morphological studies. CVA analysis also shows that the values of the six characters are not equal in taxonomy. Pygophore, forewing, hindwing and pronotum play more important roles in the classification.展开更多
基金The authors would like to express their sincere appreciation for the funding from the National Natural Science Foundation of China(Grant Nos.32071700 and 31901252)the National Key R&D Program of China(Grant No.2018YFD1101002)+1 种基金This study was also supported by the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20180276)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant Nos.18KJB220012 and 20KJB560010).
文摘Permeability of wood preservative is one of the most significant factors for protection of wood construction.Ani-sotropic flow permeability was involved in different directions of wood with higher flow resistance in the trans-verse and lower longitudinal directions.In this study,boron acid solution was brushed onto the tangential section of air-dried wood cubes and boron penetration along wood transverse direction was investigated under free dif-fusion,vacuum and HVEF treatments.Multi-scale boron distribution,FTIR measurement,leaching property,mechanical properties and fungistatic characteristic were investigated for free diffusion,vacuum and HVEF trea-ted samples respectively.The results revealed that boron exhibited high permeability along the transverse direc-tion with the penetration depth of≈35 mm for HVEF treated samples and≈1 mm for free diffusion and vacuum treated samples.For HVEF treated samples,no significant decrease of hardness,compression modulus of elasti-city and strength were found in the treated samples.Better fungistatic characteristic was showcased in HVEF trea-ted samples exposed to white rot fungi.Thus,HVEF treatment has a positive effect on boron permeability and the improvement of penetration depth of preservatives hence playing a significant role in wood protection and prolonging the service life of wood construction.
基金The work is supported by the National Natural Science Foundation of China(No.51578253)Scientific and Technological Planning Project of Xiamen City(Nos.3502Z20172011 and 3502Z20172014)+1 种基金Scientific and Technological Planning Project of Quanzhou City(No.2018C083R)Reform study of graduate education and teaching of Huaqiao University in 2018(No.18YJG55).
文摘The simplified mechanical model and finite element model are established on the basis of the measured results and analysis of the grouting pile deformation monitoring,surface horizontal displacement and vertical displacement monitoring,deep horizontal displacement(inclinometer)monitoring,soil pressure monitoring and seepage pressure monitoring in the lower reaches of Wuan River regulation project in Shishi,Fujian Province.The mechanical behavior and deformation performance of mould-bag pile retaining wall formed after controlled cement grouting in the silty stratum of the test section are analyzed and compared.The results show that the use of controlled cement grouting mould-bag pile technology is to strengthen the soft stratum for sealing water and reinforcement,so that it can rock into a retaining wall,which can both retain soil and seal water with excellent effect.The control of cement grouting technology not only makes the soft soil rock in the range of retaining wall of mould-bag pile,but also makes a wide range of soil around the mould-bag pile squeeze and embed to compaction;and its cohesion and internal friction angle increased,so as to achieve the purpose of reducing soil pressure and improving mechanical and deformation properties of retaining wall.
基金supported by the National Natural Sciences Foundation of China(31440078,31501876,31501840)Shanxi Province Programs for Science and Technology Development(20150311010-7)+1 种基金the Research Equipment Development Project of Chinese Academy of Sciences(YZ201509)the Graduate Innovation Project in Shanxi Province,China(2016BY067)
文摘The genus Eysarcoris can be easily distinguished from other genera through the two spots in the basal angle of the scutellum. Nevertheless, Eysarcoris species show complex variances. Geometric morphometric methods have been increasingly applied to distinguish species and to define the boundary of genera among insects. In the present study, geometric morphometric approach was firstly employed to evaluate the shape variation of three characters (fore wing, hind wing and pygophore) of E. guttiger, E. annamita and E. ventralis using E. aeneus as outgroup to ascertain whether this approach is a reliable method for the taxonomy of Eysarcoris. Analysis was conducted on the landmarks of the three characters of these species. Multivariate regression of procrustes coordinates against centroid size was conducted to test the presence of allometry. Principal component analysis (PCA), canonical variate analysis (CVA) and cluster analysis were utilized to describe variations in shapes among the studied species. For all of the three characters, though PCA analysis showed some overlap among species, p-values for procrustes distance and mahalanobis distance were all less than 0.0001. The distribution of the three studied species corresponds with their species status. This study demonstrates that the geometric morphometrics of both the fore wing and the hind wing might represent a possible tool for the identification of species within this genus.
基金supported by the National Natural Science Foundation of China(No.21503149)the Program for Innovative Research Team in University of Tianjin(No.TD13-5074)the Project of Hubei University of Arts and Science(Nos.xk2020043,xk2020044,2020kypyfy015)。
文摘Photocatalytic water splitting utilizing solar energy is considered as one of the most ideal strategies for solving the ene rgy and environmental issues.Recently,two-dimensional(2 D)materials with an intrinsic dipole show great chance to achieve excellent photocatalytic performance.In this work,blue-phase monolayer carbon monochalcogenides(CX,X=S,Se)are constructed and systematically studied as photocatalysts for water splitting by performing first-principles calculations based on density functional theory.After confirming the great dynamical,thermal,and mechanical stability of CX monolayers,we observe that they possess moderate band gaps(2.41 eV for CS and 2.46 eV for CSe)and high carrier mobility(3.23×10^(4)cm^(2)V^(^(-1))s^(-1)for CS and 4.27×10^(3)cm^(2)V^(-1)s^(-1)for CSe),comparable to those of many recently reported 2 D photocatalysts.Moreover,these two monolayer materials are found to have large intrinsic dipole(0.43 D for CS and 0.51 D for CSe),thus the build-in internal electric field can be selfintroduced,which can effectively drive the separation of photongenerated carriers.More importantly,the well-aligned band edge as well as rather pronounced optical absorption in the visible-light and ultraviolet regions further ensure that our proposed CX monolayers can be used as high efficient photocatalysts for water splitting.Additionally,the effects of external strain on the electronic,optical and photocatalytic properties of CX monolayers are also evaluated.These theoretical predictions will stimulate further work to open up the energy-related applications of CX monolayers.
基金supported by the National Natural Science Foundation of China(Grant No.51506051)the Open Research Fund Program of State Key Laboratory of Water Resources and Hydropower Engineering Science,Wuhan University(Grant No.2014SDG01)
文摘The study of nanobubbles (with sizes of the order of tens to hundreds of nanometers) is currently a hot spot of cavitation and bubble dynamics. In the literature, classical formulas are widely employed for the predictions of the thermal behavior of oscilla- ting macro-bubbles. However, for modelling nanobubbles, the classical formulas may not be adequate due to the effects of the surface tension. In the present paper, a formula with the effects of surface tension fully considered is proposed for the predictions of thermal behavior. The predictions based on the classical formula are also presented for comparisons to show the advantages of the present formula.
基金Project supported by the National Natural Science Foundation of China(Grant No.51506051)
文摘Owing to the part-load operations for the enhancement of grid flexibility, the Francis turbine often suffers from severe low-frequency and large-amplitude hydraulic instability, which is mostly pertinent to the highly unsteady swirling vortex rope in the draft tube. The influence of disturbances in the upstream(e.g., large-scale vortex structures in the spiral casing) on the draft-tube vortex flow is not well understood yet. In the present paper, the influence of the upstream disturbances on the vortical flow in the draft tube is studied based on the vortex identification method and the analysis of several important parameters(e.g., the swirl number and the velocity profile). For a small guide vane opening(representing the part-load condition), the vortices triggered in the spiral casing propagate downstream and significantly affect the swirling vortex-rope precession in the draft tube, leading to the changes of the intensity and the processional frequency of the swirling vortex rope. When the guide vane opening approaches the optimum one(representing the full-load condition), the upstream disturbance becomes weaker and thus its influences on the downstream flow are very limited.
基金benefited from the National Natural Sciences Foundation of China(31440078,31501840)Shanxi Province Programs for Science and Technology Development(20150311010-7)+1 种基金Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(2017169)Graduate Innovation Project in Shanxi Province(2016BY067)
文摘Further geometric morphometric analysis of the genus Eysarcoris was done based on the former studies to classified the nine Eysarcoris species from China. In this study, six characters, such as forewing, hindwing, pygophore, head, pronotum and scutellum, were selected to investigate the shape variation of Eysarcoris. Significant divergence in the shapes of the six characters was observed among the species(p 〈 0.05). For all methods, phenetic similarity based on the six characters agrees with the current status of the genus. The cluster analysis of eight species are consistent with the traditional morphological studies. CVA analysis also shows that the values of the six characters are not equal in taxonomy. Pygophore, forewing, hindwing and pronotum play more important roles in the classification.