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41.
《Comptes Rendus Mecanique》2017,345(5):317-328
In the present study, a combined finite/element approach is used to analyze failure characteristics of a rectangular hard rock with different sample height-to-width ratios based on the uniaxial compression test. The objective of this paper is to illustrate the transitional mechanisms from shear fracture to extension failure of brittle rocks and the occurrence conditions of surface-parallel slabbing. Numerical results show that failure modes have experienced the shear, tension with shear and surface-parallel slabbing failure with the decrease of sample height-to-width ratios. It is seen from the simulation results that the shear band in larger height-to-width ratios is composed of an amount of extension meso-cracks that are parallel to the loading direction, and the slabbing failure tends to be the result of the accessible propagation of extension meso-cracks due to short sample height, which validate the essence of extension failure in hard rocks. The good agreement between simulation and laboratory testing also shows the practicability and advancement of a combined finite/discrete element approach. 相似文献
42.
商业模式创新是企业本源的创新,是企业一切创新活动的基础和盈利的保障.目前,学术界和实业界对于商业模式创新仍然缺乏有效的方法和工具,在回顾商业模式相关文献的基础上,以电动汽车产业的商业模式创新为例,通过基元理论和可拓变换理论建立了流程化、形式化的商业模式创新方法.研究不仅丰富了商业模式理论,为商业模式创新提供了新的方法,同时对于丰富完善管理可拓工程理论也具有重要的意义. 相似文献
43.
J-semicommutative环的性质 总被引:1,自引:0,他引:1
环冗称为J—semicommutative若对任意B,b∈R由ab=0可以推得aRb∈J(R),这里J(R)是环R的Jacobson根.环R是J—semicommutative环当且仅当它的平凡扩张是J—semicommutative环当且仅当它的Don'oh扩张是J—semicommutative环当且仅当它的Nagata扩张是,一semicommutative环当且仅当它的幂级数环是J—semicommutative环.若R/J(R)是semicommutative环,则可得到R是J-semicommutative环.本文进一步论证了如果,是环月的一个幂零理想,且R/I是J—semicommutative环,则R也是J-semicommutative环最后给出了J—semicommutative环与其他一些常见环的联系 相似文献
44.
Les
aw Skrzypek 《Journal of Approximation Theory》2003,123(2):214-231
We will construct a minimal and co-minimal projection from Lp([0,1]n) onto Lp([0,1]n1)++Lp([0,1]nk), where n=n1++nk (see Theorem 2.9). This is a generalization of a result of Cheney, Halton and Light from (Approximation Theory in Tensor Product Spaces, Lecture Notes in Mathematics, Springer, Berlin, 1985; Math. Proc. Cambridge Philos. Soc. 97 (1985) 127; Math. Z. 191 (1986) 633) where they proved the minimality in the case n=2. We provide also some further generalizations (see Theorems 2.10 and 2.11 (Orlicz spaces) and Theorem 2.8). Also a discrete case (Theorem 2.2) is considered. Our approach differs from methods used in [8,13,20]. 相似文献
46.
47.
In the setting of a metric space equipped with a doubling measure and supporting a Poincaré inequality, and based on results by Björn and Shanmugalingam (2007) [7], we show that functions of bounded variation can be extended from any bounded uniform domain to the whole space. Closely related to extensions is the concept of boundary traces, which have previously been studied by Hakkarainen et al. (2014) [17]. On spaces that satisfy a suitable locality condition for sets of finite perimeter, we establish some basic results for the traces of functions of bounded variation. Our analysis of traces also produces novel pointwise results on the behavior of functions of bounded variation in their jump sets. 相似文献
48.
49.
《代数通讯》2013,41(5):1357-1368
Abstract The paper generalizes some of our previous results on quasi-hereditary Koszul algebras to graded standardly stratified Koszul algebras. The main result states that the class of standardly stratified algebras for which the left standard modules as well as the right proper standard modules possess a linear projective resolution – the so called linearly stratified algebras – is closed under forming their Yoneda extension algebras. This is proved using the technique of Hilbert and Poincaré series of the corresponding modules. 相似文献
50.
Changguo Wei 《Journal of Functional Analysis》2010,258(2):650-664
Let A be a unital separable nuclear C∗-algebra and let B be a stable C∗-algebra. Using K-theory and KK-theory we establish universal coefficient theorems for the stable Ext-groups of unital extensions of A by B when A and B have certain properties, which generalize a result of L. Brown and M. Dadarlat for the strong Ext-groups. The class of extensions being studied are also enlarged. 相似文献