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991.
通过平板冲击实验研究了富含微缺陷的非均质脆性固体的冲击压缩响应特性.选取“强角闪石化橄榄二辉岩”作为样品材料,利用激光速度干涉仪测量样品后自由面的速度历史,在冲击加载应力远低于样品材料Hugoniot弹性极限的条件下,观测到了表征破坏波出现的再加载信号,并且该破坏波的速度远大于玻璃中破坏波的速度,以接近于冲击波的速度在样品内向前传播,其形成机理与玻璃样品中的破坏机理不同,称之为“就位扩展机理”.采用同一冲击加载应力(~3.9GPa)作用于不同厚度的样品,获得了破坏波穿过样品的运动过程,确定出样品中破坏波的轨迹线近似为一条不过原点的直线,相应的产生此破坏波的弛豫时间约为0.5 μs. 相似文献
992.
采用Si和SiO2两种介质材料构造一维缺陷光子晶体,缺陷层介质为Si,利用传输矩阵法对带有缺陷的一维光子晶体的传光特性进行了理论分析,并得到其带隙特性.由于缺陷的存在,使得光子晶体的透射谱中产生缺陷峰.当被测温度变化时,根据两种介质的热光效应和热膨胀效应,光子晶体介质和缺陷层的光学厚度和折射率发生变化,透射谱缺陷峰产生漂移,由缺陷峰的中心波长漂移量得到被测温度的大小.构建了一维缺陷光子晶体测量温度的实验系统,实验结果表明缺陷峰中心波长与光子晶体所受的温度呈线性关系,测量灵敏度为0—2 相似文献
993.
The transmission properties of one-dimensional photonic crystals containing double-negative and singlenegative materials are studied theoretically.A special kind of photonic band gap is found in this structure.This gap is invariant with scaling and insensitive to thickness fluctuation.But when changing the ratio of the thickness of two media.the width of the gap could be enlarged.The defect modes are analyzed by inducing a linear defect layer in the structure.It is found that the number of defect modes will increase when the thickness of the defect layer becomes larger. 相似文献
994.
Lakoff的理想认知模式,即ICMs,被广泛应用于认知研究,尤其是借代的认知研究。然而,很少有学者对ICMs提出批评。本文通过对比分析Lakoff以ICMs为基础的借代模式对两个案例的解释,指出了ICMs缺乏一致性,系统性。 相似文献
995.
996.
Winfried?AuzingerEmail author Othmar?Koch Dirk?Praetorius Ewa?Weinmüller 《Numerical Algorithms》2005,40(1):79-100
In this paper, we discuss the asymptotic properties and efficiency of several a posteriori estimates for the global error of collocation methods. Proofs of the asymptotic correctness are given for regular problems and for problems with a singularity of the first kind. We were also strongly interested in finding out which of our error estimates can be applied for the efficient solution of boundary value problems in ordinary differential equations with an essential singularity. Particularly, we compare estimates based on the defect correction principle with a strategy based on mesh halving.
AMS subject classification 65L05Supported in part by the Austrian Research Fund (FWF) grant P-15072-MAT and SFB Aurora. 相似文献
997.
W.?AuzingerEmail author H.?Hofst?tter W.?Kreuzer E.?Weinmüller 《Numerical Algorithms》2005,40(3):285-303
As shown in part I of this paper and references therein, the classical method of Iterated Defect Correction (IDeC) can be
modified in several nontrivial ways, extending the flexibility and range of applications of this approach. The essential point
is an adequate definition of the defect, resulting in a significantly more robust convergence behavior of the IDeC iteration,
in particular, for nonequidistant grids. The present part II is devoted to the efficient high-order integration of stiff initial
value problems. By means of model problem investigation and systematic numerical experiments with a set of stiff test problems,
our new versions of defect correction are systematically evaluated, and further algorithmic measures are proposed for the
stiff case. The performance of the different variants under consideration is compared, and it is shown how strong coupling
between non-stiff and stiff components can be successfully handled.
AMS subject classification 65L05
Supported by the Austrian Research Fund (FWF) grant P-15030. 相似文献
998.
Specialized implants are used for transcatheter closure of septal defects, including atrial and ventricular septal defects, and patent foramen ovale. These metallic devices may pose a risk to patients undergoing magnetic resonance imaging (MRI) procedures especially if performed at 3 T. Therefore, this investigation evaluated MRI safety at 3 T for septal repair implants (CardioSEAL Septal Repair Implant and STARFlex Septal Repair Implant, NMT Medical, Boston, MA, USA) by characterizing magnetic field interactions, heating and artifacts. These implants exhibited minor magnetic field interactions; heating was not excessive (+0.5°C); and artifacts will only create a problem if the area of interest is in the same area as or near these devices. Thus, the findings indicated that it would be safe for a patient with these implants to undergo MRI at 3 T or lower. Importantly, because of the minor magnetic field interactions, MRI may be performed immediately after implantation. 相似文献
999.
Lev?B?LevitinEmail author Tommaso?Toffoli 《International Journal of Theoretical Physics》2005,44(11):1989-1994
The concepts of conditional entropy and information between subsystems of a composite quantum system are generalized to include
arbitrary indirect measurements (POVMs). Some properties of those quantities differ from those of their classical counterparts;
certain equalities and inequalities of classical information theory may be violated.
PACS: 03.67.-a. 相似文献
1000.
R. B. Alaverdyan K. R. Allahverdyan A. H. Gevorgyan S. Ts. Nersisyan A. D. Chilingaryan Yu. S. Chilingaryan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2008,43(3):109-113
A possibility to induce a planar defect in a plane-layer structure of a cholesteric liquid crystal via an external electric field is shown experimentally. The results of studies of behavior of the selective reflection (transmission) coefficient of light for a layer of the cholesteric liquid crystal, where planar defects are induced, are presented 相似文献