Fibre bundle testing is different from single-fibre measurement, not only in testing methods and instruments, but in the results obtained. For wool fibres, Sirolan-TENSOR can supply fibre-bundle tenacity (BS) and bund...Fibre bundle testing is different from single-fibre measurement, not only in testing methods and instruments, but in the results obtained. For wool fibres, Sirolan-TENSOR can supply fibre-bundle tenacity (BS) and bundle extension (BE), but has some limitations on the analysis of the measured tensile curves of fibre bundles. It has not only raised new parameters,such as initial modulus (BM) and specific work of rupture (BW), as well as the specific work before or after the peak-point(WBP or WAP) and the ratios of WAP/WBP and WAP/BW, but also compared the tensile behaviour of different fibre-bundles, e.g. wool,polyester and viscose rayon fibre- bundles. The experimental results from 32 lots of wool tops show that there are correlations between bundle tensile properties,such as BS-BE, BS-BM, BS-BW, BE-BW and BM-BW.However, the variables of coefficients of variance (CV)are almost independent of each other and have no correlation with the average values of fibre bundle tensile parameters, except for BS-CVBM and CVBM-BW.展开更多
A new lower bound on the tenacity ?of a graph G in terms of its connectivity and genus is obtained. The lower bound and interrelationship involving tenacity and other well-known graphical parameters are considered, an...A new lower bound on the tenacity ?of a graph G in terms of its connectivity and genus is obtained. The lower bound and interrelationship involving tenacity and other well-known graphical parameters are considered, and another formulation introduced from further bounds are derived.展开更多
Breeding philopatry is well known in the Black-headed Gull(Chroicocephalus ridibundus).Using a capture-markrecapture method,we studied if Black-headed Gulls show nest site tenacity and mate fidelity as well,and invest...Breeding philopatry is well known in the Black-headed Gull(Chroicocephalus ridibundus).Using a capture-markrecapture method,we studied if Black-headed Gulls show nest site tenacity and mate fidelity as well,and investigated if there are differences between a stable,and a newly established and fast-growing colony,as well as for differences between the center and edges of these colonies located in north-eastern Germany.We found a high level of nest site tenacity in the center of the stable colony on B?hmke Island,and lower degrees of nest site tenacity at the edge of the same colony and in the newly established and fast-growing colony on Riether Werder.Mate fidelity was very strong in all individuals which returned to their previous breeding place,regardless of the nest site location.展开更多
With better understanding of the quality and physico-mechanical properties of rocks of dam foundation,and the physico-mechanical properties and structure design of arch dam in association with the foundation excavatio...With better understanding of the quality and physico-mechanical properties of rocks of dam foundation,and the physico-mechanical properties and structure design of arch dam in association with the foundation excavation of Xiluodu arch dam,the excavation optimization design was proposed for the foundation surface on the basis of feasibility study.Common analysis and numerical analysis results demonstrated the feasibility of using the weakly weathered rocks III1and III2as the foundation surface of super-high arch dam.In view of changes in the geological conditions at the dam foundation along the riverbed direction,the design of extending foundation surface excavation area and using consolidating grouting and optimizing structure of dam bottom was introduced,allowing for harmonization of the arch dam and foundation.Three-dimensional(3D)geomechanics model test and fi nite element analysis results indicated that the dam body and foundation have good overload stability and high bearing capacity.The monitoring data showed that the behaviors of dam and foundation correspond with the designed patterns in the construction period and the initial operation period.展开更多
Super-high collapse resistant casings were developed by using Ti, Nb and V microalloyed CrMo steel and cross rolling techniques. A transmission electron microscope（TEM） and X-ray diffractometer were used to observe ...Super-high collapse resistant casings were developed by using Ti, Nb and V microalloyed CrMo steel and cross rolling techniques. A transmission electron microscope（TEM） and X-ray diffractometer were used to observe the characteristics of the microstructure. It was found that the （ 111 ） texture and the nano-scale precipitates distribute in a way that is beneficial to the collapse resistance, and the collapse strength of the prepared casing had a measurement, which was approximately 60% higher than the API standard value. A design concept to attain super-high collapse resistance is proposed based on the texture design and microstructure control.展开更多
In order to understand the stress corrosion behavior of super-high strength aluminum alloys by spray forming, different aluminum alloys by different heat treatment was made. The results showed that the alloy with peak...In order to understand the stress corrosion behavior of super-high strength aluminum alloys by spray forming, different aluminum alloys by different heat treatment was made. The results showed that the alloy with peak aging has the most sensitive stress corrosion cracking, the crack can even be seen using eyes;the alloys with two step aging were better than one step aging alloys, the alloys has not been found stress corrosion cracking.展开更多
Super-high pressure(SHP)technique plays an increasing role in the fields of materials science and engineering.Herein,the Mg_(97)Zn_(1)Y_(2) alloy was heat-treated under SHP(6 GPa)by cubic-anvil large-volume press with...Super-high pressure(SHP)technique plays an increasing role in the fields of materials science and engineering.Herein,the Mg_(97)Zn_(1)Y_(2) alloy was heat-treated under SHP(6 GPa)by cubic-anvil large-volume press with six rams for 2 h in the temperature range of 500–1200℃.The microstructure and mechanical properties were investigated.The results indicated that the as-cast sample consists of α-Mg equiaxed dendrites and continuous lamellar long period stacking ordered(LPSO)phase in grain boundaries.After the SHP treatment,the LPSO phase is gradually replaced by eutectic phase(Mg,Zn)_(3)Y with increasing temperature.The microhardness and strength of sample prepared at 1100℃ under SHP treatment are significantly improved compared with the as-cast one at room temperature.The improved mechanical behaviors are mainly attributed to LPSO phase kink-banding strengthening at low temperature and the precipitation strengthening of a large amount of fine(Mg,Zn)_(3)Y particles at high temperature after SHP treatment.It reveals the SHP is an effective approach to prepare high performance Mg alloys.展开更多
To deal with the problem that the initial velocity of the bullet is difficult to increase,the research on the super-high initial velocity propulsion in the barrel weapon with an adaptive pressure-maintaining chamber a...To deal with the problem that the initial velocity of the bullet is difficult to increase,the research on the super-high initial velocity propulsion in the barrel weapon with an adaptive pressure-maintaining chamber are conducted.Considering the law of gun-powder burning and the flow characteristics of gun-powder gas in multi-chamber,the scheme of super-high initial velocity propulsion with an adaptive pressure-maintaining chamber is designed,the ballistic model of the barrel weapon with super-high velocity bullet propulsion is established.The research results show that the technical scheme can greatly increase the initial velocity of the bullet with the peak pressure keeping nearly the same as the tradition barrel weapon.The research results can provide a theoretical foundation to significantly increase the initial velocity in barrel weapons using solid propellants,and have an important reference value to comprehensively increase the power of the barrel weapons.展开更多
基金the key research project of the Ministry of Education P.R.C.(No.00058)
文摘Fibre bundle testing is different from single-fibre measurement, not only in testing methods and instruments, but in the results obtained. For wool fibres, Sirolan-TENSOR can supply fibre-bundle tenacity (BS) and bundle extension (BE), but has some limitations on the analysis of the measured tensile curves of fibre bundles. It has not only raised new parameters,such as initial modulus (BM) and specific work of rupture (BW), as well as the specific work before or after the peak-point(WBP or WAP) and the ratios of WAP/WBP and WAP/BW, but also compared the tensile behaviour of different fibre-bundles, e.g. wool,polyester and viscose rayon fibre- bundles. The experimental results from 32 lots of wool tops show that there are correlations between bundle tensile properties,such as BS-BE, BS-BM, BS-BW, BE-BW and BM-BW.However, the variables of coefficients of variance (CV)are almost independent of each other and have no correlation with the average values of fibre bundle tensile parameters, except for BS-CVBM and CVBM-BW.
文摘A new lower bound on the tenacity ?of a graph G in terms of its connectivity and genus is obtained. The lower bound and interrelationship involving tenacity and other well-known graphical parameters are considered, and another formulation introduced from further bounds are derived.
文摘Breeding philopatry is well known in the Black-headed Gull(Chroicocephalus ridibundus).Using a capture-markrecapture method,we studied if Black-headed Gulls show nest site tenacity and mate fidelity as well,and investigated if there are differences between a stable,and a newly established and fast-growing colony,as well as for differences between the center and edges of these colonies located in north-eastern Germany.We found a high level of nest site tenacity in the center of the stable colony on B?hmke Island,and lower degrees of nest site tenacity at the edge of the same colony and in the newly established and fast-growing colony on Riether Werder.Mate fidelity was very strong in all individuals which returned to their previous breeding place,regardless of the nest site location.
文摘With better understanding of the quality and physico-mechanical properties of rocks of dam foundation,and the physico-mechanical properties and structure design of arch dam in association with the foundation excavation of Xiluodu arch dam,the excavation optimization design was proposed for the foundation surface on the basis of feasibility study.Common analysis and numerical analysis results demonstrated the feasibility of using the weakly weathered rocks III1and III2as the foundation surface of super-high arch dam.In view of changes in the geological conditions at the dam foundation along the riverbed direction,the design of extending foundation surface excavation area and using consolidating grouting and optimizing structure of dam bottom was introduced,allowing for harmonization of the arch dam and foundation.Three-dimensional(3D)geomechanics model test and fi nite element analysis results indicated that the dam body and foundation have good overload stability and high bearing capacity.The monitoring data showed that the behaviors of dam and foundation correspond with the designed patterns in the construction period and the initial operation period.
文摘Super-high collapse resistant casings were developed by using Ti, Nb and V microalloyed CrMo steel and cross rolling techniques. A transmission electron microscope（TEM） and X-ray diffractometer were used to observe the characteristics of the microstructure. It was found that the （ 111 ） texture and the nano-scale precipitates distribute in a way that is beneficial to the collapse resistance, and the collapse strength of the prepared casing had a measurement, which was approximately 60% higher than the API standard value. A design concept to attain super-high collapse resistance is proposed based on the texture design and microstructure control.
文摘In order to understand the stress corrosion behavior of super-high strength aluminum alloys by spray forming, different aluminum alloys by different heat treatment was made. The results showed that the alloy with peak aging has the most sensitive stress corrosion cracking, the crack can even be seen using eyes;the alloys with two step aging were better than one step aging alloys, the alloys has not been found stress corrosion cracking.
基金NSFC(51101142 and 50821001)New Century Excellent Talents in University of Ministry of Education of China(NCET-12-0690)+1 种基金Hebei province scientific program(13961002D and Y2012019)Hebei Province Technology Foundation for Selected Overseas Chinese and Outstanding Young Scholar.
文摘Super-high pressure(SHP)technique plays an increasing role in the fields of materials science and engineering.Herein,the Mg_(97)Zn_(1)Y_(2) alloy was heat-treated under SHP(6 GPa)by cubic-anvil large-volume press with six rams for 2 h in the temperature range of 500–1200℃.The microstructure and mechanical properties were investigated.The results indicated that the as-cast sample consists of α-Mg equiaxed dendrites and continuous lamellar long period stacking ordered(LPSO)phase in grain boundaries.After the SHP treatment,the LPSO phase is gradually replaced by eutectic phase(Mg,Zn)_(3)Y with increasing temperature.The microhardness and strength of sample prepared at 1100℃ under SHP treatment are significantly improved compared with the as-cast one at room temperature.The improved mechanical behaviors are mainly attributed to LPSO phase kink-banding strengthening at low temperature and the precipitation strengthening of a large amount of fine(Mg,Zn)_(3)Y particles at high temperature after SHP treatment.It reveals the SHP is an effective approach to prepare high performance Mg alloys.
基金Supported by the National Natural Science Foundation of China(51676099,51376090)the Natural Science Foundation of Jiangsu Province(BK20180473)。
文摘To deal with the problem that the initial velocity of the bullet is difficult to increase,the research on the super-high initial velocity propulsion in the barrel weapon with an adaptive pressure-maintaining chamber are conducted.Considering the law of gun-powder burning and the flow characteristics of gun-powder gas in multi-chamber,the scheme of super-high initial velocity propulsion with an adaptive pressure-maintaining chamber is designed,the ballistic model of the barrel weapon with super-high velocity bullet propulsion is established.The research results show that the technical scheme can greatly increase the initial velocity of the bullet with the peak pressure keeping nearly the same as the tradition barrel weapon.The research results can provide a theoretical foundation to significantly increase the initial velocity in barrel weapons using solid propellants,and have an important reference value to comprehensively increase the power of the barrel weapons.
