We present experimental evidence that, in the hard turbulence regime of Rayleigh-Bénard convection, the temperature fluctuations are produced by buoyancy, despite the presence of a mean horizontal flow at the plates. In a convection cell of aspect ratio 1, we measure the temperature time derivative for Ra from 2310 to 1310, which is skewed toward the negative in the region outside the cold ther...

This paper proposes a systematic procedure for the exponential stabilization of relative equilibria of mechanical systems. The emphasis is on 1 dimensional symmetries. A key design idea is to distinguish between horizontal forces, which preserve the momentum, and vertical forces that affect it. A proportional, derivative control in the horizontal directions and a first order regulator in the ve...

An approximation is obtained for the recession of a sloping aquifer. The analytical approximation can provide a useful tool to analyze data and obtain physical properties of the aquifer. In contrast to the case of a horizontal aquifer, when plotting the time derivative of the flux versus the flux on a log scale, the result shows that the flux derivative reaches a minimum value and that the curv...

Crossing of bunches at an angle in a storage ring is studied. A case when a particle trajectory intersects the opposing bunch off-center and at an angle to the main axis of the bunch charge distribution is considered. Formulae for a kick experienced by a particle are derived for crossing in both horizontal and vertical planes. This kick is a function of the off-center distance in the longitudin...

The simplest illustration of a steerable function is the first-order directional derivative of a two-dimensional Gaussian. Although we will only consider Gaussians, the principle of steerability may be extended to any differentiable function. For notational simplicity we will consider a unit-variant Gaussian and ignore the 1 p2 scaling constant: g(x; y) = e (x2+y2)=2: (1) Lets begin by consider...

This paper presents an easy-to-use open source computer algorithm (code) for estimating the depths of isolated single thin dike-like source bodies by using numerical second-, third-, and fourth-order horizontal derivatives computed from observed magnetic anomalies. The approach does not require a priori information and uses some filters of successive graticule spacings. The computed higher-orde...

We analyze Bouguer anomalies in/around the focal region of the 2016 Kumamoto earthquake to examine features, such as continuity, segmentation and faulting type, of the active fault zones related to the earthquake. Several derivatives and structural parameters calculated from a gravity gradient tensor are applied to highlight the features. First horizontal and vertical derivatives, as well as a ...

A noncommutative-geometric generalization of the theory of principal bundles is sketched. A differential calculus over corresponding quantum principal bundles is analysed. The formalism of connections is presented. In particular, operators of covariant derivative and horizontal projection are described and analysed. Quantum counterparts for the Bianchi identity and the Weil’s homomorphism are f...

The visual systems in primates are organized around orientation with a rich set of long-range horizontal connections. We abstract this from a differential-geometric perspective, and introduce the covariant derivative of frame fields as a general framework for early vision. This paper overviews our research showing how curve detection, texture, shading, color (hue), and stereo can be unified wit...

It is well established that the free-space Green's function can be recovered from the two-point cross-correlation function of a random noise field if the noise is white and isotropic. Ambient noise in the ocean rarely satisfies either of these conditions. However, a non-uniform spectrum could be pre-whitened by the application of a suitable filter but anisotropy cannot be so readily eliminated....