Search results for "Geometry"

Par n dimensiju Eiklīda telpas līknēm

1936

On osculation, superosculation and characteristic points

1943

Translated into English by D. Zeps Original text: Par oskulāciju, superoskulāciju un charakteristiskiem punktiem, https://dspace.lu.lv/dspace/handle/7/46435 Facsimile of the manuscript of dissertation: https://dspace.lu.lv/dspace/handle/7/46446 Facsimile of the manuscript of computations: https://dspace.lu.lv/dspace/handle/7/46433 Page numbers in translation are from original in Latvian

Par oskulāciju, superoskulāciju un charakteristiskiem punktiem. Disertācijas manuskripta faksimils

1943

On Grinbergs' differential geometry and finite fields

2019

Emanuels Grinbergs, in his youth, during ten years, from 1933 until 1943, wrote three dissertations on one subject, namely, differential geometry [1, 2, 3]. We think that his work in this direction has been neglected for many years, and it is the last time to try to understand the significance of these works. Here, in this short article we touch only one aspect of this work, and compare and put together two approaches, one from thesis of Grinbergs [3], and another, of the author's, [5, 6], where we show close relation between both.

Daži pētījumi par telpas ruletēm

1933

Darbs kvalificēts kā Kandidāta darbs, Konkursa darbs, iesniegts LŪ, Matēmatikas nodaļai 1933. g. 14. augustā. Stud. math. Emanuels Grünbergs, Matr. 14875. Motto "Patientia vincet." Disertācijā 143 lpp. Publicējam bez pilnā teksta arī disertācijas ievadu.

Decentralized Deployment of Mobile Sensors for Optimal Connected Sensing Coverage

2008

In this paper, we address the optimal connected sensing coverage problem, i.e., how mobile sensors with limited sensing capabilities can cooperatively adjust their locations so as to maximize the extension of the covered area while avoiding any internal “holes”, areas that are not covered by any sensor. Our solution consists in a distributed motion algorithm that is based on an original extension of the Voronoi tessellation.

Squeezing of Quantum Noise of Motion in a Micromechanical Resonator

2015

A pair of conjugate observables, such as the quadrature amplitudes of harmonic motion, have fundamental fluctuations which are bound by the Heisenberg uncertainty relation. However, in a squeezed quantum state, fluctuations of a quantity can be reduced below the standard quantum limit, at the cost of increased fluctuations of the conjugate variable. Here we prepare a nearly macroscopic moving body, realized as a micromechanical resonator, in a squeezed quantum state. We obtain squeezing of one quadrature amplitude $1.1 \pm 0.4$ dB below the standard quantum limit, thus achieving a long-standing goal of obtaining motional squeezing in a macroscopic object.

Natural induction: An objective bayesian approach

2009

The statistical analysis of a sample taken from a finite population is a classic problem for which no generally accepted objective Bayesian results seem to exist. Bayesian solutions to this problem may be very sensitive to the choice of the prior, and there is no consensus as to the appropriate prior to use.

Principal Component and Neural Network Analyses of Face Images: What Can Be Generalized in Gender Classification?

1998

We present an overview of the major findings of the principal component analysis (pca) approach to facial analysis. In a neural network or connectionist framework, this approach is known as the linear autoassociator approach. Faces are represented as a weighted sum of macrofeatures (eigenvectors or eigenfaces) extracted from a cross-product matrix of face images. Using gender categorization as an illustration, we analyze the robustness of this type of facial representation. We show that eigenvectors representing general categorical information can be estimated using a very small set of faces and that the information they convey is generalizable to new faces of the same population and to a l…

Influence of geometric variations on LV activation times: A study on an atlas-based virtual population

2010

We present the fully automated pipeline we have developed to obtain electrophysiological simulations of the heart on a large atlas-based virtual population. This virtual population was generated from a statistical model of left ventricular geometry, represented by a surface model. Correspondence between tetrahedralized volumetric meshes was obtained using Thin Plate Spline warps. Simulations are based on the fast solving of Eikonal equations, and stimulation sites correspond to physiological activation. We report variations of total activation time introduced by geometry, as well as variations in the location of last activation. The obtained results suggest that the total activation time ha…