We present a density fitted local configuration interaction singles (CIS) method for calculating optical bandgaps in 3D-periodic systems. We employ an Ewald technique to carry out infinite lattice summations for the exciton-exciton interaction, and robust product-density specific local density fitting in direct space for the electron-hole interaction. Moreover, we propose an alternative to the ...

GALCIT, the Graduate Aeronautical Laboratories at the California Institute of Technology, is a system now 50 years old, with which I have been associated for nearly 40 years. Conceived by R. A. Millikan as part of his general scheme to construct a small, very high level technological school, GALCIT was built up by Theodore von Karman (in the spirit of Felix Klein) to serve as a center for the f...

Through the wind velocity and direction monitoring system installed on Jiubao Bridge of Qiantang River, Hangzhou city, Zhejiang province, China, a full range of wind velocity and direction data was collected during typhoon HAIKUI in 2012. Based on these data, it was found that, at higher observed elevation, turbulence intensity is lower, and the variation tendency of longitudinal and lateral tu...

We perform 2-D simulations of earthquakes on rough faults in media with random heterogeneities (with von Karman distribution) to study the effects of geometric and material heterogeneity on the rupture process and resulting high-frequency ground motions in the near-fault region (out to ∼20 km). Variations in slip and rupture velocity can arise from material heterogeneity alone but are dominantl...

The Bénard-von Karman vortex shedding instability in the wake of a cylinder is perhaps the best known example of a supercritical Hopf bifurcation in fluid dynamics. However, a simplified physical description that accurately accounts for the saturation amplitude of the instability is still missing. Here we present a simple self-consistent model that provides a clear description of the saturation...

We study the influence of von Karman nonlinearity, van der Waals force, and a athermal stresses on pull-in instability and small vibrations of electrostatically actuated mi-croplates. We use the Galerkin method to develop a tractable reduced-order model for elec-trostatically actuated clamped rectangular microplates in the presence of van der Waals forcesand thermal stresses. More specifically,...

The plant hormone auxin is fundamental for plant growth, and its spatial distribution in plant tissues is critical for plant morphogenesis. We consider a leading model of the polar auxin flux, and study in full detail the stability of the possible equilibrium configurations. We show that the critical states of the auxin transport process are composed of basic building blocks, which are isolated...

The elastic energy functional of a thin elastic rod or sheet is generalized to the case of an M -dimensional manifold in N -dimensional space. We derive potentials for the stress field and curvatures and find the generalized von Karman equations for a manifold in elastic equilibrium. We perform a scaling analysis of an M − 1 dimensional ridge in an M = N − 1 dimensional manifold. A ridge of lin...

Fluid and structural systems and their possible interaction have a rich array of behavior being susceptible to instabilities and thus the generation of limit cycle oscillations and on occasion chaotic response. in this talk we will touch on several example including solar sails, high performance aircraft and aerodynamic decelerators from space into planetary atmospheres. Much of the talk will b...

We have studied the finite-size effect on the dynamic behavior of graphene resonators and their applications in atomic mass detection using a continuum elastic model such as modified plate theory. In particular, we developed a model based on von Karman plate theory with including the edge stress, which arises from the imbalance between the coordination numbers of bulk atoms and edge atoms of gr...