[ Objective] The difference of mineral element content in healthy bark of P. armandii and bark affected by C. nbicola were compared, which would provide theoretical foundation for exploring new ways to control the dis...[ Objective] The difference of mineral element content in healthy bark of P. armandii and bark affected by C. nbicola were compared, which would provide theoretical foundation for exploring new ways to control the disease by artificial water and fertilizer. [ Method] Inductively Coupled Plasma Optical Emission Spectrometer（ ICP-OES）was adopted to measure the variation of mineral elements content in bark after P. armandii was affected by C. nbicola. [Result] 45 mineral elements in the healthy bark and 46 mineral elements in affected bark caused by C. ribicola were detected. These mineral elements contained 14 kinds of mineral elements which were necessary for plant growth and 31 kinds of other mineral elements （32 kinds after affected disease）. The total content of mineral elements in affected bark of P. armandii decreased for 15.77%, in which necessary elements for plant growth decreased for 15.54% and other elements decreased for 17.07%. The content of Ca decreased the most, decrease rate was about 75%. The order of content was also changed, they were Na 〉 Ca 〉 B 〉 K 〉 Si 〉 Mg 〉 S 〉 P in healthy bark, and Na 〉 B 〉 K 〉 Ca 〉 Mg 〉 P 〉 Si 〉 S in affected bark. [ Conclusion] The results laid foundation for controlling C. ribicola through application of mineral elements.展开更多
Numerical solution of shallow-water equations （SWE） has been a challenging task because of its nonlinear hyperbolic nature, admitting discontinuous solution, and the need to satisfy the C-property. The presence of s...Numerical solution of shallow-water equations （SWE） has been a challenging task because of its nonlinear hyperbolic nature, admitting discontinuous solution, and the need to satisfy the C-property. The presence of source terms in momentum equations, such as the bottom slope and friction of bed, compounds the difficulties further. In this paper, a least-squares finite-element method for the space discretization and θ-method for the time integration is developed for the 2D non-conservative SWE including the source terms. Advantages of the method include： the source terms can be approximated easily with interpolation functions, no upwind scheme is needed, as well as the resulting system equations is symmetric and positive-definite, therefore, can be solved efficiently with the conjugate gradient method. The method is applied to steady and unsteady flows, subcritical and transcritical flow over a bump, 1D and 2D circular dam-break, wave past a circular cylinder, as well as wave past a hump. Computed results show good C-property, conservation property and compare well with exact solutions and other numerical results for flows with weak and mild gradient changes, but lead to inaccurate predictions for flows with strong gradient changes and discontinuities.展开更多
The effect of converter high pressure combined blowing technology on the damage of MgO-C permeable elements is discussed in the paper.A remnant high pressure gas permeable element is used to analyse the damage mechani...The effect of converter high pressure combined blowing technology on the damage of MgO-C permeable elements is discussed in the paper.A remnant high pressure gas permeable element is used to analyse the damage mechanism of high pressure permeable element.The view that spall caused by high concentrated thermal stress and intensive erosion-wear action cause high pressure gas permeable elements damage mainly and a reasonable measures to increase the service life of MgO-C high pressure permeable elements are also introduced in the paper.展开更多
A program for calculating the aerodynamic properties of hypersonic vehicles based on the surface element method was developed using the general-purpose programming language C++. The calculated values of lift coefficie...A program for calculating the aerodynamic properties of hypersonic vehicles based on the surface element method was developed using the general-purpose programming language C++. The calculated values of lift coefficients, drag coefficients, and surface pressure coefficients are discussed with the results of wind tunnel experiments using the HL-20 lift body and the NASA hypersonic aircraft STS Columbia OV-102 as research subjects. Finally, the results of the experimental and wind tunnel studies of the aerodynamic characteristics of the HL-20 lift body at an altitude of 65 km and Mach numbers of 6 and 10 Ma are discussed. The maximum error in the aerodynamic characteristics at 6 Ma does not exceed 3%, consistent with the results. The maximum error at 10 Ma occurs in the 11° - 14° angle of attack and does not exceed 10%, which is still within the error tolerance. The STS results for NASA’s hypersonic aircraft were also tested using this procedure. Experimental aerodynamic data for the Colombian OV-102 aircraft. The results show that the program takes only 10 minutes to calculate the results, with no more than 2% error from the wind tunnel experimental results.展开更多
C^1 natural element method （C^1 NEM） is applied to strain gradient linear elasticity, and size effects on mi crostructures are analyzed. The shape functions in C^1 NEM are built upon the natural neighbor interpolati...C^1 natural element method （C^1 NEM） is applied to strain gradient linear elasticity, and size effects on mi crostructures are analyzed. The shape functions in C^1 NEM are built upon the natural neighbor interpolation （NNI）, with interpolation realized to nodal function and nodal gradient values, so that the essential boundary conditions （EBCs） can be imposed directly in a Galerkin scheme for partial differential equations （PDEs）. In the present paper, C^1 NEM for strain gradient linear elasticity is constructed, and sev- eral typical examples which have analytical solutions are presented to illustrate the effectiveness of the constructed method. In its application to microstructures, the size effects of bending stiffness and stress concentration factor （SCF） are studied for microspeciem and microgripper, respectively. It is observed that the size effects become rather strong when the width of spring for microgripper, the radius of circular perforation and the long axis of elliptical perforation for microspeciem come close to the material characteristic length scales. For the U-shaped notch, the size effects decline obviously with increasing notch radius, and decline mildly with increasing length of notch.展开更多
The precise microscopic feature of carbon-carbon（C/C） composites is essential {or an accurate predic tion of their mechanical behavior. After fabrication, actual microscopic feature differs from simple ideal spatial...The precise microscopic feature of carbon-carbon（C/C） composites is essential {or an accurate predic tion of their mechanical behavior. After fabrication, actual microscopic feature differs from simple ideal spatial model. Micro computed lomography（CT） scan can well describe internal microstruetures of composites. Therefore, a reconstructed model is developed based on mireo-CT, by a series of prodcedures including extrac tlng components, generating new binary images and establishing a finite element （FE） model. Compared with the model designed by reconstructed commercial software MIMICS. the presented reconstructed FE model is superior in terms of high mesh quality and eontrollable mesh cluantity. The precision of the model is verified by experiment.展开更多
The omnivorous fish species, <i>C. nigrodigitatus</i> feeds mainly on benthic organisms and may therefore consume contaminated food throughout its food web. This can lead to the bioaccumulation of contamin...The omnivorous fish species, <i>C. nigrodigitatus</i> feeds mainly on benthic organisms and may therefore consume contaminated food throughout its food web. This can lead to the bioaccumulation of contaminants such as trace elements in their tissues. However, fish consumption is a major pathway of human exposure to contaminants which may cause public health problems. The aim of the present study is to assess trace elements contamination in some species from the food web of <i>C. nigrodigitatus</i>. For this, 10 main food items of the silver catfish were collected at two sites from February to July 2017 and analyzed using an Atomic Absorption Spectrometer coupled with a hydride and cold vapour generator. The concentrations of trace elements varied greatly from one species to another and within each species. These values ranged from 0.007 mg/kg for Hg in C hippos to 354.84 mg/kg for Mn in <i>P. fusca</i>. The most contaminated species by trace elements were benthic organisms: <i>M. perna</i> (Cd, Pb, Hg), <i>Pagurus</i> sp. (Cr, Ni, Cu, Zn), <i>G. paradoxa</i> (As) and <i>P. fusca</i> (Mn). The average concentrations of trace elements found in species were, for the most part, above WHO standards except Hg in <i>M. perna</i> and <i>G. paradoxa</i>. The water-based bioconcentration factors (BCFw) reach 92.58 for Cd, 44.72 for Pb, 382.49 for Hg and 1514.34 for As in <i>M. perna</i>. It is therefore necessary to pay particular attention to this ecosystem and to put in place a better management plan.展开更多
基金Supported by The 10~(th) Five-Years Key Programs for Science and Technology Development of Yunnan Province(2003NG12)~~
文摘[ Objective] The difference of mineral element content in healthy bark of P. armandii and bark affected by C. nbicola were compared, which would provide theoretical foundation for exploring new ways to control the disease by artificial water and fertilizer. [ Method] Inductively Coupled Plasma Optical Emission Spectrometer（ ICP-OES）was adopted to measure the variation of mineral elements content in bark after P. armandii was affected by C. nbicola. [Result] 45 mineral elements in the healthy bark and 46 mineral elements in affected bark caused by C. ribicola were detected. These mineral elements contained 14 kinds of mineral elements which were necessary for plant growth and 31 kinds of other mineral elements （32 kinds after affected disease）. The total content of mineral elements in affected bark of P. armandii decreased for 15.77%, in which necessary elements for plant growth decreased for 15.54% and other elements decreased for 17.07%. The content of Ca decreased the most, decrease rate was about 75%. The order of content was also changed, they were Na 〉 Ca 〉 B 〉 K 〉 Si 〉 Mg 〉 S 〉 P in healthy bark, and Na 〉 B 〉 K 〉 Ca 〉 Mg 〉 P 〉 Si 〉 S in affected bark. [ Conclusion] The results laid foundation for controlling C. ribicola through application of mineral elements.
基金the National Science Council of Taiwan for funding this research (NSC 96-2221-E-019-061).
文摘Numerical solution of shallow-water equations （SWE） has been a challenging task because of its nonlinear hyperbolic nature, admitting discontinuous solution, and the need to satisfy the C-property. The presence of source terms in momentum equations, such as the bottom slope and friction of bed, compounds the difficulties further. In this paper, a least-squares finite-element method for the space discretization and θ-method for the time integration is developed for the 2D non-conservative SWE including the source terms. Advantages of the method include： the source terms can be approximated easily with interpolation functions, no upwind scheme is needed, as well as the resulting system equations is symmetric and positive-definite, therefore, can be solved efficiently with the conjugate gradient method. The method is applied to steady and unsteady flows, subcritical and transcritical flow over a bump, 1D and 2D circular dam-break, wave past a circular cylinder, as well as wave past a hump. Computed results show good C-property, conservation property and compare well with exact solutions and other numerical results for flows with weak and mild gradient changes, but lead to inaccurate predictions for flows with strong gradient changes and discontinuities.
文摘The effect of converter high pressure combined blowing technology on the damage of MgO-C permeable elements is discussed in the paper.A remnant high pressure gas permeable element is used to analyse the damage mechanism of high pressure permeable element.The view that spall caused by high concentrated thermal stress and intensive erosion-wear action cause high pressure gas permeable elements damage mainly and a reasonable measures to increase the service life of MgO-C high pressure permeable elements are also introduced in the paper.
文摘A program for calculating the aerodynamic properties of hypersonic vehicles based on the surface element method was developed using the general-purpose programming language C++. The calculated values of lift coefficients, drag coefficients, and surface pressure coefficients are discussed with the results of wind tunnel experiments using the HL-20 lift body and the NASA hypersonic aircraft STS Columbia OV-102 as research subjects. Finally, the results of the experimental and wind tunnel studies of the aerodynamic characteristics of the HL-20 lift body at an altitude of 65 km and Mach numbers of 6 and 10 Ma are discussed. The maximum error in the aerodynamic characteristics at 6 Ma does not exceed 3%, consistent with the results. The maximum error at 10 Ma occurs in the 11° - 14° angle of attack and does not exceed 10%, which is still within the error tolerance. The STS results for NASA’s hypersonic aircraft were also tested using this procedure. Experimental aerodynamic data for the Colombian OV-102 aircraft. The results show that the program takes only 10 minutes to calculate the results, with no more than 2% error from the wind tunnel experimental results.
基金supported by the SDUST Spring Bud (2009AZZ021)Taian Science and Technology Development (20112001)
文摘C^1 natural element method （C^1 NEM） is applied to strain gradient linear elasticity, and size effects on mi crostructures are analyzed. The shape functions in C^1 NEM are built upon the natural neighbor interpolation （NNI）, with interpolation realized to nodal function and nodal gradient values, so that the essential boundary conditions （EBCs） can be imposed directly in a Galerkin scheme for partial differential equations （PDEs）. In the present paper, C^1 NEM for strain gradient linear elasticity is constructed, and sev- eral typical examples which have analytical solutions are presented to illustrate the effectiveness of the constructed method. In its application to microstructures, the size effects of bending stiffness and stress concentration factor （SCF） are studied for microspeciem and microgripper, respectively. It is observed that the size effects become rather strong when the width of spring for microgripper, the radius of circular perforation and the long axis of elliptical perforation for microspeciem come close to the material characteristic length scales. For the U-shaped notch, the size effects decline obviously with increasing notch radius, and decline mildly with increasing length of notch.
基金supported by the National Natural Science Foundation of China (Nos.11272147,10772078)the Aviation Science Foundation (No.2013ZF52074)+1 种基金the State Key Laboratory of Mechanical Structural Mechanics and Control (No.0214G02)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘The precise microscopic feature of carbon-carbon（C/C） composites is essential {or an accurate predic tion of their mechanical behavior. After fabrication, actual microscopic feature differs from simple ideal spatial model. Micro computed lomography（CT） scan can well describe internal microstruetures of composites. Therefore, a reconstructed model is developed based on mireo-CT, by a series of prodcedures including extrac tlng components, generating new binary images and establishing a finite element （FE） model. Compared with the model designed by reconstructed commercial software MIMICS. the presented reconstructed FE model is superior in terms of high mesh quality and eontrollable mesh cluantity. The precision of the model is verified by experiment.
文摘The omnivorous fish species, <i>C. nigrodigitatus</i> feeds mainly on benthic organisms and may therefore consume contaminated food throughout its food web. This can lead to the bioaccumulation of contaminants such as trace elements in their tissues. However, fish consumption is a major pathway of human exposure to contaminants which may cause public health problems. The aim of the present study is to assess trace elements contamination in some species from the food web of <i>C. nigrodigitatus</i>. For this, 10 main food items of the silver catfish were collected at two sites from February to July 2017 and analyzed using an Atomic Absorption Spectrometer coupled with a hydride and cold vapour generator. The concentrations of trace elements varied greatly from one species to another and within each species. These values ranged from 0.007 mg/kg for Hg in C hippos to 354.84 mg/kg for Mn in <i>P. fusca</i>. The most contaminated species by trace elements were benthic organisms: <i>M. perna</i> (Cd, Pb, Hg), <i>Pagurus</i> sp. (Cr, Ni, Cu, Zn), <i>G. paradoxa</i> (As) and <i>P. fusca</i> (Mn). The average concentrations of trace elements found in species were, for the most part, above WHO standards except Hg in <i>M. perna</i> and <i>G. paradoxa</i>. The water-based bioconcentration factors (BCFw) reach 92.58 for Cd, 44.72 for Pb, 382.49 for Hg and 1514.34 for As in <i>M. perna</i>. It is therefore necessary to pay particular attention to this ecosystem and to put in place a better management plan.
