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排序方式: 共有1110条查询结果,搜索用时 31 毫秒
1.
《Comptes Rendus Mecanique》2019,347(8):601-614
During machining processes, materials undergo severe deformations that lead to different behavior than in the case of slow deformation. The microstructure changes, as a consequence, affect the materials properties and therefore influence the functionality of the component. Developing material models capable of capturing such changes is therefore critical to better understand the interaction process–materials. In this paper, we introduce a new physics model associating Mechanical Threshold Stress (MTS) with Dislocation Density (DD) models. The modeling and the experimental results of a series of large strain experiments on polycrystalline copper (OFHC) involving sequences of shear deformation and strain rate (varying from quasi-static to dynamic) are very similar to those observed in processes such as machining. The Kocks–Mecking model, using the mechanical threshold stress as an internal state variable, correlates well with experimental results and strain rate jump experiments. This model was compared to the well-known Johnson–Cook model that showed some shortcomings in capturing the stain jump. The results show a high effect of rate sensitivity of strain hardening at large strains. Coupling the mechanical threshold stress dislocation density (MTS–DD), material models were implemented in the Abaqus/Explicit FE code. The model shows potentialities in predicting an increase in dislocation density and a reduction in cell size. It could ideally be used in the modeling of machining processes. 相似文献
2.
钙钛矿稀土正铁氧体RFeO3具有丰富的磁性,这主要源于4f电子层的稀土离子和3d电子层的铁离子之间复杂的相互作用。磁化跃迁作为RFeO3体系中的重要现象,是指体系中的稀土离子磁矩和铁离子磁矩在特定的磁场和温度下发生180°旋转,宏观表现为磁热曲线中磁化强度发生断崖式变化。本文综述了不同化合物RFeO3的两种磁化跃迁现象,第一类磁化跃迁通常具有补偿点,FR与FFe的排列耦合方向不变,第二类磁化跃迁则相反,且两类磁化跃迁出现的温区受外加磁场的调控。 相似文献
3.
The purpose of this paper is to study a new two-step iterative scheme with mean errors of mixed type for two asymptotically nonexpansive self-mappings and two asymptotically nonexpansive nonself-mappin... 相似文献
4.
本文从理论上研究了在双色频率梳激光场驱动下多光子谐波辐射光谱中的相位突变现象。我们利用Floquet理论非微扰地模拟了频率梳激光场与原子分子等量子系统的相互作用过程。谐波辐射信号是多光子偶极跃迁相干叠加的结果,通过调节频率梳激光场间的相对相位,可以相干地控制谐波辐射信号的强度。通过对谐波信号进行傅里叶变换,可以提取不同跃迁路径的相对相位信息。我们通过改变频率梳组激光场的强度和频率组分实现多光子跃迁频率,让其跨越共振跃迁频率时,谐波相位会发生突变。从而可以观测超强激光场驱动下量子系统共振跃迁频率的斯塔克能移。 相似文献
5.
《Stochastic Processes and their Applications》2020,130(5):2596-2638
In this paper we introduce a new generalisation of the relative Fisher Information for Markov jump processes on a finite or countable state space, and prove an inequality which connects this object with the relative entropy and a large deviation rate functional. In addition to possessing various favourable properties, we show that this generalised Fisher Information converges to the classical Fisher Information in an appropriate limit. We then use this generalised Fisher Information and the aforementioned inequality to qualitatively study coarse-graining problems for jump processes on discrete spaces. 相似文献
6.
In this article, we establish the existence of the solution to the càdlàg perturbed Skorohod problem. As an application, we obtain the existence and uniqueness of the solution to the perturbed reflected jump diffusion processes. 相似文献
7.
8.
In this paper, we extend the previous Markov-modulated
reflected Brownian motion model discussed in [1] to a Markov-modulated
reflected jump diffusion process, where the jump component is described as a
Markov-modulated compound Poisson process. We compute the joint stationary
distribution of the bivariate Markov jump process. An abstract example with two
states is given to illustrate how the stationary equation described as a system
of ordinary integro-differential equations is solved by choosing appropriate
boundary conditions. As a special case, we also give the sationary distribution
for this Markov jump process but without Markovian regime-switching. 相似文献
9.
In this paper, the asymptotic behavior of the weak solution (u_t)_{t\ge0} to the non-local Cauchy problems as stated in (1) is considered. Only using lower bounds of jumping kernel J(x,y) for large |x-y|, it is obtained that \|u_t\|_p\le c(t)\|u_0\|_q with any 1\le q
相似文献
10.
Results of classical molecular dynamics simulations are presented for the re-orientational dynamics of water hydrogen bonded to perchlorate anion. Different mechanisms of bond formation are presented. Due to its regular tetrahedron geometry the perchlorate anion can make classical as well as bifurcated and trifurcated hydrogen bonds. The angular variation of water in the first solvation shell of perchlorate suggests the transitional character of multi-centred hydrogen bonds. As a result water molecules can slide around the anion. 相似文献