原岩应力的理论分析及数值模拟

原岩应力对地下工程稳定性具有重要影响,是地下工程破坏和变形的根本作用力。数值模拟在岩土工程中已经广泛应用,而原岩应力会直接影响到模拟结果的准确性和合理性。由于原岩应力成因复杂,分布规律性差,所以成为研究地下工程稳定性首先要解决的一个问题。介绍了原岩应力的成因,从理论推导和数值模拟两方面对自重应力进行了分析研究,并且两者得到了一致的结果。     

An evolution of pulse speed in arteries

In this work, treating the artery as a thick-walled cylindrical shell made of an incompressible, isotropic and elastic solid, utilizing the large deformation theory and the stress-strain relation proposed by Demiray (1976b, Trans. ASME Ser. E, J. Appl. Mech., 98, 194-197), an explicit expression for the pulse speed is obtained and the effect of lumen pressure and the axial stretch on wave speed is discussed. Numerical results indicate that the wave speed increases with lumen pressure but decreases with the axial stretch. The results of the present model are compared with our previous work (Demiray, 1988, J. Biomech. 21, 55-58) on the same subject.     

Induction of optical density waves and chemotactic cell movement in Dictyostelium discoideum by microinjection of cAMP pulses

This paper reviews recent developments in the area of computer-assisted analysis of mixture distributions (C.A.MAN). Given a biometric situation of interest in which, under homogeneity assumptions, a certain parametric density occurs, such as the Poisson, the binomial, the geometric, the normal, and so forth, then it is argued that this situation can easily be enlarged to allow a variation of the scalar parameter in the population. This situation is called unobserved heterogeneity. This naturally leads to a specific form of nonparametric mixture distribution that can then be assumed to be the standard model in the biometric application of interest (since it also incorporates the homogeneous situations as a special case). Besides developments in theory and algorithms, the work focuses on developments in biometric applications such as meta-analysis, fertility studies, estimation of prevalence under clustering, and estimation of the distribution function of survival time under interval censoring. The approach is nonparametric for the mixing distribution, including leaving the number of components (subpopulations) of the mixing distribution unknown.