Basalt fibers/7075 aluminum matrix composites were studied to meet the demand of aluminum alloy drill pipes for material wear resistance.The composites with different basalt fiber additions were prepared by hot presse...Basalt fibers/7075 aluminum matrix composites were studied to meet the demand of aluminum alloy drill pipes for material wear resistance.The composites with different basalt fiber additions were prepared by hot pressed sintering and hot extrusion.The mechanical properties as well as friction and wear properties of the composites were studied by microstructure analysis,tensile experiments,friction and wear experiments.The results showed that basalt fibers were oriented and uniformly distributed and led to local grain refinement in the alloy matrix.The hardness and elongation of the composites were improved.The friction coefficient of the composites increased and then decreased,and the maximum wear depth and wear amount decreased,then increased,then decreased again with the growth of basalt fiber addition.Meanwhile,the inclusion of basalt fibers mitigated the uneven wear of the extruded 7075 aluminum alloy.The value of wear depth difference of 7075-0.2BF was the smallest,and that of 7075-2.0BF was close to it.The maximum wear depth and wear volume the 7075-0.2BF and 7075-2.0BF were also the smallest.The inhibition of uneven wear by basalt fibers enhanced of wear resistance for 7075 aluminum alloy,which has reference significance for improving the performance of aluminum alloy drill pipes.展开更多
Cotton,an important industrial crop cultivated in more than 70 countries,plays a major role in the livelihood of millions of farmers and industrialists.Cotton is mainly grown for its fiber,an economic component that c...Cotton,an important industrial crop cultivated in more than 70 countries,plays a major role in the livelihood of millions of farmers and industrialists.Cotton is mainly grown for its fiber,an economic component that can be differentiated from its epidermal cells in the outer integument of a developing seed.Fiber length,fiber strength,and fiber fineness are three main attributes that contribute to the quality of cotton fibers.Recent advancements in genomics have identified key genes,which are the most important factors that govern these three traits,can be introduced into cultivars of interest via gene editing,marker-assisted selection,and transgenics,thus the narrow genetic background of cotton can be addressed and its fiber quality traits can be enhanced.Over the past two decades,quantitative trait loci(QTLs)have been mapped for different fiber traits,approximately 1850 QTLs have been mapped for fiber length,fiber strength,and fineness among which a few genes have been edited for quality improvement in cotton.In this background,the current review covers the development and the factors that influence these traits,along with the reported genes,QTLs,and the edited genomes for trait improvement.展开更多
This paper investigates the design of an attitude autopilot for a dual-channel controlled spinning glideguided projectile(SGGP),addressing model uncertainties and external disturbances.Based on fixed-time stable theor...This paper investigates the design of an attitude autopilot for a dual-channel controlled spinning glideguided projectile(SGGP),addressing model uncertainties and external disturbances.Based on fixed-time stable theory,a disturbance observer with integral sliding mode and adaptive techniques is proposed to mitigate total disturbance effects,irrespective of initial conditions.By introducing an error integral signal,the dynamics of the SGGP are transformed into two separate second-order fully actuated systems.Subsequently,employing the high-order fully actuated approach and a parametric approach,the nonlinear dynamics of the SGGP are recast into a constant linear closed-loop system,ensuring that the projectile's attitude asymptotically tracks the given goal with the desired eigenstructure.Under the proposed composite control framework,the ultimately uniformly bounded stability of the closed-loop system is rigorously demonstrated via the Lyapunov method.Validation of the effectiveness of the proposed attitude autopilot design is provided through extensive numerical simulations.展开更多
为探究高强高延性混凝土(high-strength and high-ductility concrete,HSHDC)的单轴拉伸性能,设计了12组试件进行了薄板单轴拉伸试验,研究了水胶比(0.14、0.16和0.18)、PE纤维体积率(1.5%、2.0%、2.5%)、纤维种类(PE和PVA)及PE纤维直径...为探究高强高延性混凝土(high-strength and high-ductility concrete,HSHDC)的单轴拉伸性能,设计了12组试件进行了薄板单轴拉伸试验,研究了水胶比(0.14、0.16和0.18)、PE纤维体积率(1.5%、2.0%、2.5%)、纤维种类(PE和PVA)及PE纤维直径(22μm、35μm和40μm)对薄板单轴拉伸行为的影响.并利用峰值前应变能密度分析了上述因素对HSHDC能量吸收能力的影响.结果表明:随着水胶比的增大,HSHDC的抗拉强度呈先升高后降低的趋势,而极限拉伸应变呈增大趋势;HSHDC的抗拉强度随着纤维体积率的增加而增大,而HSHDC的极限拉伸应变在水胶比较小时随着纤维体积率的增加而减小,在水胶比较大时则相反;与0.14水胶比相比,在0.16和0.18水胶比下,HSHDC的峰值前应变能密度较大;与掺入PVA纤维的HSHDC试件相比,掺入PE纤维的HSHDC的拉伸性能和能量吸收能力更优,且小直径的PE纤维更适合制备HSHDC.最后,利用扫描电子显微镜(scanning electron microscope,SEM)研究了HSHDC致密的基体和粗糙的PE纤维表面.展开更多
基金Project(2021YFC2900200)supported by the National Key Research and Development Project of ChinaProject(20230203114SF)supported by the Key Research and Development Project of Jilin Province,China。
文摘Basalt fibers/7075 aluminum matrix composites were studied to meet the demand of aluminum alloy drill pipes for material wear resistance.The composites with different basalt fiber additions were prepared by hot pressed sintering and hot extrusion.The mechanical properties as well as friction and wear properties of the composites were studied by microstructure analysis,tensile experiments,friction and wear experiments.The results showed that basalt fibers were oriented and uniformly distributed and led to local grain refinement in the alloy matrix.The hardness and elongation of the composites were improved.The friction coefficient of the composites increased and then decreased,and the maximum wear depth and wear amount decreased,then increased,then decreased again with the growth of basalt fiber addition.Meanwhile,the inclusion of basalt fibers mitigated the uneven wear of the extruded 7075 aluminum alloy.The value of wear depth difference of 7075-0.2BF was the smallest,and that of 7075-2.0BF was close to it.The maximum wear depth and wear volume the 7075-0.2BF and 7075-2.0BF were also the smallest.The inhibition of uneven wear by basalt fibers enhanced of wear resistance for 7075 aluminum alloy,which has reference significance for improving the performance of aluminum alloy drill pipes.
文摘Cotton,an important industrial crop cultivated in more than 70 countries,plays a major role in the livelihood of millions of farmers and industrialists.Cotton is mainly grown for its fiber,an economic component that can be differentiated from its epidermal cells in the outer integument of a developing seed.Fiber length,fiber strength,and fiber fineness are three main attributes that contribute to the quality of cotton fibers.Recent advancements in genomics have identified key genes,which are the most important factors that govern these three traits,can be introduced into cultivars of interest via gene editing,marker-assisted selection,and transgenics,thus the narrow genetic background of cotton can be addressed and its fiber quality traits can be enhanced.Over the past two decades,quantitative trait loci(QTLs)have been mapped for different fiber traits,approximately 1850 QTLs have been mapped for fiber length,fiber strength,and fineness among which a few genes have been edited for quality improvement in cotton.In this background,the current review covers the development and the factors that influence these traits,along with the reported genes,QTLs,and the edited genomes for trait improvement.
基金supported by the National Natural Science Foundation of China(Grant Nos.52272358 and 62103052)。
文摘This paper investigates the design of an attitude autopilot for a dual-channel controlled spinning glideguided projectile(SGGP),addressing model uncertainties and external disturbances.Based on fixed-time stable theory,a disturbance observer with integral sliding mode and adaptive techniques is proposed to mitigate total disturbance effects,irrespective of initial conditions.By introducing an error integral signal,the dynamics of the SGGP are transformed into two separate second-order fully actuated systems.Subsequently,employing the high-order fully actuated approach and a parametric approach,the nonlinear dynamics of the SGGP are recast into a constant linear closed-loop system,ensuring that the projectile's attitude asymptotically tracks the given goal with the desired eigenstructure.Under the proposed composite control framework,the ultimately uniformly bounded stability of the closed-loop system is rigorously demonstrated via the Lyapunov method.Validation of the effectiveness of the proposed attitude autopilot design is provided through extensive numerical simulations.
文摘为探究高强高延性混凝土(high-strength and high-ductility concrete,HSHDC)的单轴拉伸性能,设计了12组试件进行了薄板单轴拉伸试验,研究了水胶比(0.14、0.16和0.18)、PE纤维体积率(1.5%、2.0%、2.5%)、纤维种类(PE和PVA)及PE纤维直径(22μm、35μm和40μm)对薄板单轴拉伸行为的影响.并利用峰值前应变能密度分析了上述因素对HSHDC能量吸收能力的影响.结果表明:随着水胶比的增大,HSHDC的抗拉强度呈先升高后降低的趋势,而极限拉伸应变呈增大趋势;HSHDC的抗拉强度随着纤维体积率的增加而增大,而HSHDC的极限拉伸应变在水胶比较小时随着纤维体积率的增加而减小,在水胶比较大时则相反;与0.14水胶比相比,在0.16和0.18水胶比下,HSHDC的峰值前应变能密度较大;与掺入PVA纤维的HSHDC试件相比,掺入PE纤维的HSHDC的拉伸性能和能量吸收能力更优,且小直径的PE纤维更适合制备HSHDC.最后,利用扫描电子显微镜(scanning electron microscope,SEM)研究了HSHDC致密的基体和粗糙的PE纤维表面.
