Modules over double crossproducts of Skew-Hopf pairs

1　ＩｎｔｒｏｄｕｃｔｉｏｎａｎｄＰｒｅｌｉｍｉｎａｒｉｅｓＱｕａｎｔｕｍＹａｎｇ＿Ｂａｘｔｅｒ (ｄｅｎｏｔｅｄｂｙＱＹＢＥ)ｗａｓｓｕｇｇｅｓｔｅｄｂｙＹａｎｇＣＮａｎｄＢａｘｔｅｒＲＪｉｎＲｅｆｓ.[1 ,2 ] ,ｂａｓｅｄｏｎｒｉｃｈｐｈｙｓｉｃａｌｂａｃｋｇｒｏｕｎｄ ,ｒｅｌａｔｅｄｔｏｍａｎｙｏｔｈｅｒｂｒａｎｃｈｅｓ:ｔｈｅＢｅｔｈｅＡｎｓａｔｚ,ｓｏｌｖａｂｌｅｌａｔｔｉｃｅｍｏｄｅｌｓ,ｑｕａｎｔｕｍｉｎｖｅｒｓｅｓｃａｔｔｅｒｉｎｇｍｅｔｈｏｄｓ ,ｃｏｎｆｏｒｍａｌｆｉｅｌｄｔｈｅｏｒｙ ,…     

AMITABH BANERJEE AND THAKUR BALWANT SINGH A FIXED POINT THEOREM FOR SET-VALUED MAPPINGS

Fixed points for set-valued mappings from a metric space X(not necessarily complete)into B(X), the collection of nonempty bounded subsets of X are obtained. The result generalizes some known results.     

挠性转子系统碰摩故障传播特性的实验研究

研究了柔性联接的双跨度挠性转子发生碰摩时系统的响应征兆;将振动信号的快速付立叶变换(FFT)幅值谱阵列和轴心轨迹设置为特征参量,对不同截面和2个相互垂直方位的碰摩特征进行了对比.结果表明:碰摩故障在转子间具有传播能力,靠近碰摩部位的响应强度最大;碰摩的典型特征表现为FFT谱中1X分量幅值增大,并出现2X、3X、4X谐波分量;轴心轨迹形状显示出碰摩作用点的截面方位信息;最典型征兆表现为碰摩响应的1X分量所对应的频率坐标降低,其降低幅度与碰摩的程度相关.     

Homotopy Classes of Self-Maps of Annuli, Generalised Twists and Spin Degree

Let X be a [generalised] annulus and consider the space of continuous self-maps of X, that is,

核爆X光辐照铝靶产生的脉冲应力波的简化解析估算

高空核爆炸大约有７０％的能量以Ｘ射线形式向外辐射，高能通量密度的Ｘ射线辐照在空间结构物上，在其表面的能量沉积将产生脉冲应力波（通常又称为热击波），这样的脉冲应力波可造成壳体材料的动力学破坏。对于试验研究人员来说希望采用简化解析模型对于其参数作出直观、快速的预测。并以简化模型估算了核爆Ｘ射线谱的特征、Ｘ光辐照铝靶产生的脉冲应力波的初始参数及其沿铝靶厚度的衰减特性。     

A note on a theorem of Tas, Telci and Fisher

I.IntroductionInarecentpaperTas,TelciandFisherlZ],obtainedthefollowingimprovedandgeneralizedversionofafixedpointtheoremofSharmaandSahulll:TheoremALet.A,B,SandTbeselfmappillgsonacompletemetricspace(X,ti,satisfyingA(X)GT(X)andB(X)GS(X)(l.l)[d(Ax,By)]2$Clmax{[d(Sx,Ax)]',[d(Ty,By)jZ,[d(Sx,Ty)]2} cd.max{d(Sx,Ax).d(Sx,By),d(Ax,Ty).d(By,Ty)} c,.d(Sx,By).d(Ty,As)(1.2)t'orallx,yinX,whereof,cZ,c3>0,of 2c2相似文献   

Dynamics of Induced Maps on the Space of Probability Measures

Journal of Dynamics and Differential Equations - For a continuous self-map f on a compact metric space X, we provide two simple examples: the first confirms that shadowing of (X, f) is not...     

脉冲X射线辐照材料引起的汽化反冲冲量

分析比较了计算Ｘ射线辐照固体材料引起汽化反冲冲量的几种计算公式。通过对Ｘ射线辐照后材料运动过程的数值模拟和分析，提出了一种计算汽化反冲冲量的数值计算公式。计算结果表明:数值计算得到的汽化反冲冲量与ＢＢＡＹ公式的结果比较接近；脉冲Ｘ射线引起的汽化反冲冲量与Ｘ射线的能谱及辐照量有明显的依赖关系，且汽化反冲冲量随辐照量的变化是非线性的。     

Central Circular Sections of the Strain Ellipsoids

A simple direct proof is given of the known result that in any deformation x = x(X), the planes of the central circular sections of the material strain-ellipsoid at X are deformed into the planes of the spatial strain-ellipsoid at x. This revised version was published online in August 2006 with corrections to the Cover Date.     

S0兰姆波在渐变折射率声透镜中的聚焦

本文研究了S₀兰姆波在渐变折射率声子晶体中的聚焦现象．通过调整正方晶格声子晶体的主轴方向与波传播的相对方向,设计了ΓX和ΓM方向两组不同的渐变折射率声透镜．采用有限单元法模拟S0波在不同声透镜内的传播,并与S₀波在声透镜内的传播迹线做了对比,数值结果和理论结果基本一致．数值计算结果显示：ΓX方向的声透镜的焦距fl略大于其理论值,而ΓM方向的声透镜的fl则略小于其理论值．ΓX方向的声透镜的横向分辨率FWHM小于ΓM方向的声透镜,而聚焦强度MFI则大于ΓM方向的声透镜．结果表明,通过调整声子晶体的主轴方向与波传播的相对方向,可以显著地改变声透镜的聚焦特征．这为S₀兰姆波声透镜的设计提供了重要依据．     

X80管道单腐蚀缺陷失效研究

腐蚀是造成管道失效的重要原因之一。为了深入了解现有X80管道的单腐蚀缺陷,本文针对X80管道单腐蚀缺陷失效机理进行了研究。首先建立并验证了有限元模型,通过大量的有限元模拟计算,建立了单腐蚀X80管道失效分析数据库;其次根据计算结果对腐蚀管道的失效机理进行了研究,包括单腐蚀X80管道的破坏模式、破坏过程以及应力分析;同时对影响X80腐蚀管道失效表现的各项参数进行了分析,如深度、长度、宽度、缺陷位置及管道径厚比等;最后利用有限元计算结果,拟合了单腐蚀X80管道的失效压力预测公式,并通过对比爆破实验数据验证了回归公式的适用性。     

Iterative construction of solutions to nonlinear equations of lipschitzian and local strongly accretive operators

In this paper, we investigate the Ishikawa iteration process in a p-uniformly smooth Banach space X. Let T: X→X be a Lipschitzian and local strongly accretive operator and the set sol(T) of solutions of the equation Tx=f be nonempty. We show that sol(T) is a singleton and the Ishikawa sequence converges strongly to the unique solution of the equation Tx=f. In addition, whenever T is a Lipschitzian and local pseudocontractive mapping from a nonempty convex subset K of X and the set F(T) of fixed points of T is nonempty, we prove that F(T) is a singleton and the Ishikawa sequence converges strongly to the unique fixed point of T. Our results are the improvements and extension of the results of Deng and Ding⁽⁴⁾ and Tan and Xu⁽⁵⁾.     

On a gas source in a constant force field

The nonbarochronic regular partially invariant submodel of the equations of gas dynamics is studied. The submodel reduces to an implicit ordinary differential equation of the first order for an auxiliary function X = X(x). The physical quantities (velocity, density, and pressure) are expressed in terms of the function X. The properties of the solutions of the equation are investigated and interpreted physically in terms of gas motion. The existence of a shock-wave solution is proved. The properties of the shock adiabat are studied. It is shown that the results obtained are new and differ significantly from the results for the case of no constant force. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 6, pp. 3–16, November–December, 2006.     

Contaminant contraction in two-dimensional oscillatory flows

If the vertically-mixing time is comparable with that of period oscillatory current,the contaminant contraction may occur.The coefficient of shear dispersion is negative(singularity).According to the two-dimensional delay-diffusion equation derived by theauthor:where u(t),v(t)are vertically-averaged velocities,the equations for X(t),Y(t),central displacement,dispersion tensor,had been derived.αD_(ij)/τis positivewhenτis small.If theτis large,the memory functions may be negative.Also theexpressions for D_(ij)and X,Y had been obtained.     

Explorative study of costs, effects and savings of screening for female fragile X premutation and full mutation carriers in the general population

OBJECTIVE: Evaluation of the costs, effects and savings of three strategies for female fragile X premutation and full mutation carrier screening in the general population. METHODS: We calculated the costs, effects and savings by using a general model for prenatal, preconceptional, and school carrier screening. Assumptions were based on literature data, expert opinions, prices and tariffs. RESULTS: Prenatal screening will detect most carriers and will lead to the highest number of avoided fragile X syndrome patients. The costs per detected carrier are quite similar for all screening programmes (around USD 45,000). All screening strategies have a favourable cost-savings balance (USD 14 million for prenatal screening, USD 9 million for preconceptional screening and USD 2 million for school screening). CONCLUSIONS: From an economic point of view, there is no obstacle to fragile X screening. The decision to screen or not can (and should) therefore concentrate on discussion of medical, social, psychological and ethical considerations.     

Free-piston driver optimisation for simulation of high Mach number scramjet flow conditions

The University of Queensland (UQ) is currently developing high Mach number, high total pressure scramjet flow conditions in its X2 and X3 expansion tube facilities. These conditions involve shock-processing a high-density air test gas followed by its unsteady expansion into a low-pressure acceleration tube. This relatively slow shock-processing requires the driver to supply high pressure gas for a significantly greater duration than normally required for superorbital flow conditions. One technique to extend the duration is to operate a tuned free-piston driver. For X2, this involves the use of a very light piston at high speeds so that, following diaphragm rupture, the piston displacement substitutes for vented driver gas, thus maintaining driver pressure much longer. However, this presents challenges in terms of higher piston loading and also safely stopping the piston. This article discusses the tuned driver concept, the design of a very lightweight but highly stressed piston, and details the successful development of a new set of tuned free-piston driver conditions for X2.     

Tension fracture behaviors of welded joints in X70 steel pipeline

The surface of welded joints in X70 steel pipeline was processed by laser shock wave, its mechanical behaviors of tension fracture were analyzed with tension test, and the fracture morphologies and the distributions of chemical element were observed with scanning electron microscope and energy dispersive spectrum, respectively. The experimental results show that the phenomenon of grain refinement occurs in the surface of welded joints in X70 steel pipeline after the laser shock processing, and compressive residual stress is formed in its surface strengthened layer. There is no yield stage but a continuous yield behavior in the welded joints in X70 steel pipeline after the laser shock processing, and its extensibility has decreased by 20 %. The welded joints in X70 steel pipeline in primitive state exhibits brittle fracture with less tearing edges, while the fracture of welded joints in X70 steel pipeline processed by laser shock is ductile fracture with a lot of tearing edges.     

On a dynamical system on matrix algebra

LetM(n) be the algebra of alln×n complex matrices. We consider a dynamical system onM(n) defined by the vector fieldV(X)=[[X ^*,X],X], (X M(n)). It arises as the gradient flow for two kinds of variational problems onM(n). Given anyX ₀ M(n), letX(t) be the trajectory starting atX ₀. We study the global behavior ofX(t) ast . We show that, ifX ₀ is semisimple, thenX(t) converges exponentially to a normal matrix. IfX ₀ is not semisimple, then the behavior ofX(t) is completely different and difficult to analyze. We give some results also in this case. Furthermore, we discuss about a center manifold approach to our dynamical system.     

Minimal Spaces with Cyclic Group of Homeomorphisms

There are two main subjects in this paper. (1) For a topological dynamical system \((X,T)\) we study the topological entropy of its “functional envelopes” (the action of \(T\) by left composition on the space of all continuous self-maps or on the space of all self-homeomorphisms of \(X\)). In particular we prove that for zero-dimensional spaces \(X\) both entropies are infinite except when \(T\) is equicontinuous (then both equal zero). (2) We call Slovak space any compact metric space whose homeomorphism group is cyclic and generated by a minimal homeomorphism. Using Slovak spaces we provide examples of (minimal) systems \((X,T)\) with positive entropy, yet, whose functional envelope on homeomorphisms has entropy zero (answering a question posed by Kolyada and Semikina). Finally, also using Slovak spaces, we resolve a long standing open problem whether the circle is a unique non-degenerate continuum admitting minimal continuous transformations but only invertible: No, some Slovak spaces are such, as well.     

Some measurements in a binary gas jet

Simultaneous measurements of species volume concentration and velocities in a helium/air binary gas jet with a jet Reynolds number of 4,300 and a jet-to-ambient fluid density ratio of 0.64 were carried out using a laser/hot-wire technique. From the measurements, the turbulent axial and radial mass fluxes were evaluated together with the means, variances and spatial gradients of the mixture density and velocity. In the jet near field (up to ten diameters downstream of the jet exit), detailed measurements of u/ ₀ U ₀, v/ ₀ U₀, u v/ ₀ U ₀ ² , u ² / ₀ U ₀ ² and v ² / ₀ U ₀ ² reveal that the first three terms are of the same order of magnitude, while the last two are at least one order of magnitude smaller than the first three. Therefore, the binary gas jet in the near field cannot be approximated by a set of Reynolds-averaged boundary-layer equations. Both the mean and turbulent velocity and density fields achieve self-preservation around 24 diameters. Jet growth and centerline decay measurements are consistent with existing data on binary gas jets and the growth rate of the velocity field is slightly slower than that of the scalar field. Finally, the turbulent axial mass flux is found to follow gradient diffusion relation near the center of the jet, but the relation is not valid in other regions where the flow is intermittent.