The two-step hydro-bulge forming technique was proposed to manufacture the ellipsoidal shell with the length ratio of the long axis to the short axis larger than 1.4. A central tube was introduced into the first step ...The two-step hydro-bulge forming technique was proposed to manufacture the ellipsoidal shell with the length ratio of the long axis to the short axis larger than 1.4. A central tube was introduced into the first step of the hydro-bulge forming process to constrain the over growth of the short axis during bulging,and then the central tube was replaced with two polar plates in the second step of the hydro-bulge forming process to manufacture an integral ellipsoidal shell. It is shown that the central tube restricts the growth of the short axis and simultaneously reduces the shrunk tendency of the long axis. The wrinkling occurs due to the latitudinal compressive stress at the equator at the early stage of hydro-bulge forming. However,with the increase of internal pressure,the compressive stress areas gradually decrease and finally the tensile latitudinal stress occupies approximately the whole shell,thus the wrinkles are eliminated. A sound ellipsoidal shell with the axis length ratio of 1.8 is obtained after two-step hydro bulging.展开更多
Release programs to enhance stocks of ark shell(Anadara broughtonii) have been undertaken in a number of Asian countries,but their effectiveness has rarely been investigated owing to a lack of marking methods.The qual...Release programs to enhance stocks of ark shell(Anadara broughtonii) have been undertaken in a number of Asian countries,but their effectiveness has rarely been investigated owing to a lack of marking methods.The quality and longevity of fluorescent markers,alizarin red S(ARS) and calcein(CAL)(200 and 300 mg/L),as well as clip tags,were tested on juvenile A.broughtonii.No significant differences in survival or shell growth were observed in juveniles stained with either of the two fluorochromes after a 160-day culture period,but the retention rate was 100%after 1 year.Fluorescent marks(>grade 3) were observable microscopically in juveniles stained with the two fluorochromes,and some fluorescent marks(>grade 4) were visible with the naked eye after 1 year.ARS-marked shells were brighter than those marked with CAL,and shells marked with 300 mg/L of the fluorochromes were easier to detect than those marked with 200 mg/L.Clip tags were incorporated into the shell as the bivalve grew,and the retention rate was64.25%after 160 days.Significant differences in survival(at 30 days),shell length(at 60,90,120,and 160days),and wet weight(at 90,120,and 160 days) were observed between the clip-tagged and control groups(all P<0.05),indicating that the tags may have passive effects on the ark shell.The results suggest that both ARS and CAL are suitable to mark A.broughtonii for large-scale restocking programs,and that optimal marking quality was achieved with 300 mg/L ARS.Lighter and smaller clip tags need to be developed to reduce injury and increase survival rate of clams.展开更多
The single-layer latticed cylindrical shell is one of the most widely adopted space-fl'amed structures.In this paper,free vibration properties and dynamic response to horizontal and vertical seismic waves of singl...The single-layer latticed cylindrical shell is one of the most widely adopted space-fl'amed structures.In this paper,free vibration properties and dynamic response to horizontal and vertical seismic waves of single-layer latticed cylindrical shells are analyzed by the finite element method using ANSYS software.In the numerical study,where hundreds of cases were analyzed,the parameters considered included rise-span ratio,length-span ratio,surface load and member section size.Moreover,to better define the actual behavior of single-layer latticed shells,the study is focused on the dynamic stress response to both axial forces and bending moments.Based on the numerical results,the effects of the parameters considered on the stresses are discussed and a modified seismic force coefficient method is suggested.In addition,some advice based on these research results is presented to help in the future design of such structures.展开更多
基金Sponsored by the National Natural Science Foundation of China (Grant No. 59975022 and 50275034)
文摘The two-step hydro-bulge forming technique was proposed to manufacture the ellipsoidal shell with the length ratio of the long axis to the short axis larger than 1.4. A central tube was introduced into the first step of the hydro-bulge forming process to constrain the over growth of the short axis during bulging,and then the central tube was replaced with two polar plates in the second step of the hydro-bulge forming process to manufacture an integral ellipsoidal shell. It is shown that the central tube restricts the growth of the short axis and simultaneously reduces the shrunk tendency of the long axis. The wrinkling occurs due to the latitudinal compressive stress at the equator at the early stage of hydro-bulge forming. However,with the increase of internal pressure,the compressive stress areas gradually decrease and finally the tensile latitudinal stress occupies approximately the whole shell,thus the wrinkles are eliminated. A sound ellipsoidal shell with the axis length ratio of 1.8 is obtained after two-step hydro bulging.
基金Supported by the Special Fund for Agro-Scientific Research in the Public Interest(No.201003068)the National Department Public Benefit Research Foundation(No.201305043)
文摘Release programs to enhance stocks of ark shell(Anadara broughtonii) have been undertaken in a number of Asian countries,but their effectiveness has rarely been investigated owing to a lack of marking methods.The quality and longevity of fluorescent markers,alizarin red S(ARS) and calcein(CAL)(200 and 300 mg/L),as well as clip tags,were tested on juvenile A.broughtonii.No significant differences in survival or shell growth were observed in juveniles stained with either of the two fluorochromes after a 160-day culture period,but the retention rate was 100%after 1 year.Fluorescent marks(>grade 3) were observable microscopically in juveniles stained with the two fluorochromes,and some fluorescent marks(>grade 4) were visible with the naked eye after 1 year.ARS-marked shells were brighter than those marked with CAL,and shells marked with 300 mg/L of the fluorochromes were easier to detect than those marked with 200 mg/L.Clip tags were incorporated into the shell as the bivalve grew,and the retention rate was64.25%after 160 days.Significant differences in survival(at 30 days),shell length(at 60,90,120,and 160days),and wet weight(at 90,120,and 160 days) were observed between the clip-tagged and control groups(all P<0.05),indicating that the tags may have passive effects on the ark shell.The results suggest that both ARS and CAL are suitable to mark A.broughtonii for large-scale restocking programs,and that optimal marking quality was achieved with 300 mg/L ARS.Lighter and smaller clip tags need to be developed to reduce injury and increase survival rate of clams.
基金National Natural Science Foundation of China,Grant No.59895410
文摘The single-layer latticed cylindrical shell is one of the most widely adopted space-fl'amed structures.In this paper,free vibration properties and dynamic response to horizontal and vertical seismic waves of single-layer latticed cylindrical shells are analyzed by the finite element method using ANSYS software.In the numerical study,where hundreds of cases were analyzed,the parameters considered included rise-span ratio,length-span ratio,surface load and member section size.Moreover,to better define the actual behavior of single-layer latticed shells,the study is focused on the dynamic stress response to both axial forces and bending moments.Based on the numerical results,the effects of the parameters considered on the stresses are discussed and a modified seismic force coefficient method is suggested.In addition,some advice based on these research results is presented to help in the future design of such structures.
