This paper describes an approach for controlling the attitude of statically unsable thrust-levitated vehicles in hover or slow translation. The large thrust vector that characterizes such vehicles can be modulated to provide control forces and moments to the airframe, but such modulation is accompanied by significant unsteady flow effects. These effects are difficult to model, and can compromis...

We explore the presence of torques at the inner edges of geometrically-thin black hole accretion disks using 3-dimensional magnetohydrodynamic (MHD) simulations in a pseudo-Newtonian potential. By varying the saturation level of the magnetorotational instability that leads to angular momentum transport, we show that the dynamics of gas inside the radius of marginal stability varies depending up...

BACKGROUND Self-reported knee joint instability compromises function in individuals with medial knee osteoarthritis and may be related to impaired joint mechanics. The purpose of this study was to evaluate the relationship between self-reported instability and the passive varus-valgus mechanical behaviour of the medial osteoarthritis knee. METHODS Passive varus-valgus angular laxity and stiff...

Abstract. In this paper, we prove some a priori stability estimates (in weighted Sobolev spaces) for the spatially homogeneous Boltzmann equation without angular cutoff (covering every physical collision kernels). These estimates are conditioned to some regularity estimates on the solutions, and therefore reduce the stability and uniqueness issue to the one of proving suitable regularity bounds...

The stability of spacecraft attitude is studied with considering sinusoidal disturbance. A passive attitude controller without angular velocity measurement for spacecraft described by quaternion is designed. The passive controller has no information related to system parameters. So it has robustness to model error and uncertainty of model parameters. The stability of spacecraft attitude control...

The contrast provided by diffusion MRI has been exploited repeatedly for in vivo segmentations of thalamic nuclei. This paper systematically investigates the benefits of high-angular resolution (HARDI) data for this purpose. An empirical analysis of clustering stability reveals a clear advantage of acquiring HARDI data at b = 1000 s/mm2. However, based on stability arguments, as well as further...

The transient motion and the heat transfer of a viscous incompressible flow contained between two vertically eccentric spheres maintained at different temperatures and rotating about a common axis with different angular velocities is numerically considered when the angular velocities are an arbitrary functions of time. The resulting flow pattern, temperature distribution, and heat transfer char...

Reversible and adaptive integration methods based on Kustaanheimo-Stiefel regularization and modiied Sundman transformations are applied to simulate general perturbed Kepler motion and to compute classical trajectories of atomic systems (e.g. Rydberg atoms). The new family of reversible adaptive regulariza-tion (RAR) methods also conserve angular momentum and exhibit superior energy conservatio...

The control and stability derivatives of Yardstik to be used for simulation are generated using the Tornado software. Tornado is a 3-D vortex lattice program written in Matlab environment which makes use of the vortex lattice method for obtaining the forces and moment acting on the aerodynamic surfaces [2]. From these forces and moment generated, we are able to obtain the stability and control ...

This short note complements the recent paper of the authors [2]. We revisit the results on propagation of regularity and stability using Lp estimates for the gain and loss collision operators which had the exponent range misstated for the loss operator. We show here the correct range of exponents. We require a Lebesgue’s exponent α > 1 in the angular part of the collision kernel in order to obt...