A new code concept is used for the L1 civil（L1C） signal of the global positioning system（GPS）.The generation of L1C codes is quite different from the generation of traditional ranging codes.Thus,it is necessary to...A new code concept is used for the L1 civil（L1C） signal of the global positioning system（GPS）.The generation of L1C codes is quite different from the generation of traditional ranging codes.Thus,it is necessary to find a method for the correct generation to pave the way for future research.L1C codes are based on only one Legendre sequence which consists of Legendre symbols.To calculate these Legendre symbols,the Euler criterion is always used to evaluate quadratic residues.However,due to the great length of L1C codes,this procedure causes overflow problems.Therefore,the quadratic reciprocity law,some related theorems and properties are introduced to solve the problems.Moreover,if the quadratic reciprocity law,some related theorems and properties are used to calculate different Legendre symbols,the combination modes may vary,which causes a complex generation process.The proposed generation method deals with this complex generation process effectively.In addition,through simulations,it is found that the autocorrelation features of obtained Legendre sequences and L1C codes are in accordance with theoretical results,which proves the correctness of the proposed method.展开更多
Based on the governing equations of the inner cyinder of the unsteady flow of the power law fluid in eccentric annuli with the inner cylinder reciprocating axially in bipolar coordinate system, the calculation formula...Based on the governing equations of the inner cyinder of the unsteady flow of the power law fluid in eccentric annuli with the inner cylinder reciprocating axially in bipolar coordinate system, the calculation formulae of tangential force were established, and the relevant numerical calculation method was given. Taking the aqueous solution of partially hydrolyzed polyacrylamides (HPAM) for examples, the tangential forces were calculated by using the formulae and numerical calculation method mentioned above;the curves of the tangential force on the wall of the inner cylinder of HPAM aqueous solution were plotted;and the effects on the tangential force of the flow behavior index of the power law fluid, the stroke and the stroke frequency of the inner cylinder were analyzed.展开更多
Initially, all that was known about diffraction in quasicrystals was its point group symmetry;nothing was known about the mechanism. The structure was more evident, and was called quasiperiodic. From mapping the Mn at...Initially, all that was known about diffraction in quasicrystals was its point group symmetry;nothing was known about the mechanism. The structure was more evident, and was called quasiperiodic. From mapping the Mn atoms by phase-contrast, optimum-defocus, electron microscopy, the progress towards identifying unit cell, cluster, supercluster and extensive hierarchic structure is evident. The structure is ordered and uniquely icosahedral. From the known structure, we could calculate structure factors. They were all zero. The quasi structure factor is an iterative procedure on the hierarchic structure that correctly calculates diffraction beam intensities in 3-dimensional space. By a creative device, the diffraction is demonstrated to occur off the Bragg condition;the quasi-Bragg condition implies a metric that enables definition and measurement of the lattice constant. The reciprocal lattice is the 3-dimensional diffraction pattern. Typically, it builds on Euclidean axes with coordinates in geometric series, but it also transforms to Cartesian coordinates.展开更多
针对桥梁墩柱和承台内的粘结滑移现象,基于fib混凝土规范(fib Model Code)推荐的混凝土粘结滑移模型,推导了纵筋滑移量的计算公式,并通过对墩柱塑性区域受拉纵筋的应力-应变本构进行修正,以引入墩柱塑性区域和承台内的纵筋滑移量,作为...针对桥梁墩柱和承台内的粘结滑移现象,基于fib混凝土规范(fib Model Code)推荐的混凝土粘结滑移模型,推导了纵筋滑移量的计算公式,并通过对墩柱塑性区域受拉纵筋的应力-应变本构进行修正,以引入墩柱塑性区域和承台内的纵筋滑移量,作为一种等效方法,以考虑粘结滑移对墩柱地震响应的影响,并用试验结果验证了该方法的合理性。此外,还对所提等效方法和零长度截面单元法的计算结果进行了对比。结果表明:未考虑粘结滑移会高估墩柱的侧向刚度、累计滞回耗能和残余位移,且无法客观反映滑移导致的墩柱强度退化问题;零长度截面单元法和所提等效方法均能考虑强度退化问题,但前者对粘结滑移的模拟效果受纵筋直径影响显著,后者则能合理捕捉滑移影响下的墩柱往复加载过程。展开更多
基金supported by the National High Technology Research and Development Program of China(863Program)(2011AA110101)the National Basic Research Program of China(973Program)(2009CB724002)
文摘A new code concept is used for the L1 civil（L1C） signal of the global positioning system（GPS）.The generation of L1C codes is quite different from the generation of traditional ranging codes.Thus,it is necessary to find a method for the correct generation to pave the way for future research.L1C codes are based on only one Legendre sequence which consists of Legendre symbols.To calculate these Legendre symbols,the Euler criterion is always used to evaluate quadratic residues.However,due to the great length of L1C codes,this procedure causes overflow problems.Therefore,the quadratic reciprocity law,some related theorems and properties are introduced to solve the problems.Moreover,if the quadratic reciprocity law,some related theorems and properties are used to calculate different Legendre symbols,the combination modes may vary,which causes a complex generation process.The proposed generation method deals with this complex generation process effectively.In addition,through simulations,it is found that the autocorrelation features of obtained Legendre sequences and L1C codes are in accordance with theoretical results,which proves the correctness of the proposed method.
文摘Based on the governing equations of the inner cyinder of the unsteady flow of the power law fluid in eccentric annuli with the inner cylinder reciprocating axially in bipolar coordinate system, the calculation formulae of tangential force were established, and the relevant numerical calculation method was given. Taking the aqueous solution of partially hydrolyzed polyacrylamides (HPAM) for examples, the tangential forces were calculated by using the formulae and numerical calculation method mentioned above;the curves of the tangential force on the wall of the inner cylinder of HPAM aqueous solution were plotted;and the effects on the tangential force of the flow behavior index of the power law fluid, the stroke and the stroke frequency of the inner cylinder were analyzed.
文摘Initially, all that was known about diffraction in quasicrystals was its point group symmetry;nothing was known about the mechanism. The structure was more evident, and was called quasiperiodic. From mapping the Mn atoms by phase-contrast, optimum-defocus, electron microscopy, the progress towards identifying unit cell, cluster, supercluster and extensive hierarchic structure is evident. The structure is ordered and uniquely icosahedral. From the known structure, we could calculate structure factors. They were all zero. The quasi structure factor is an iterative procedure on the hierarchic structure that correctly calculates diffraction beam intensities in 3-dimensional space. By a creative device, the diffraction is demonstrated to occur off the Bragg condition;the quasi-Bragg condition implies a metric that enables definition and measurement of the lattice constant. The reciprocal lattice is the 3-dimensional diffraction pattern. Typically, it builds on Euclidean axes with coordinates in geometric series, but it also transforms to Cartesian coordinates.
文摘针对桥梁墩柱和承台内的粘结滑移现象,基于fib混凝土规范(fib Model Code)推荐的混凝土粘结滑移模型,推导了纵筋滑移量的计算公式,并通过对墩柱塑性区域受拉纵筋的应力-应变本构进行修正,以引入墩柱塑性区域和承台内的纵筋滑移量,作为一种等效方法,以考虑粘结滑移对墩柱地震响应的影响,并用试验结果验证了该方法的合理性。此外,还对所提等效方法和零长度截面单元法的计算结果进行了对比。结果表明:未考虑粘结滑移会高估墩柱的侧向刚度、累计滞回耗能和残余位移,且无法客观反映滑移导致的墩柱强度退化问题;零长度截面单元法和所提等效方法均能考虑强度退化问题,但前者对粘结滑移的模拟效果受纵筋直径影响显著,后者则能合理捕捉滑移影响下的墩柱往复加载过程。
