Formation of particle tracks

Abstract

The formation of particle tracks, and such phenomena as the detection of charged particles, and the damage produced by charged particles, are intimately related to the spatial distribution of ionization energy deposited by δ-rays. Changes in the spectrum of δ-rays with the velocity of the primary particle, imply that linear measures of the interaction of the primary particle with the medium, such as specific energy loss, or primary ionization, are unsatisfactory measures of effects produced in the medium, for they contain no knowledge of the spatial deposition of the lost energy.     

Average acoustic pulse dispersion length in condensed matter channels

This paper is concerned with ‘a probing pulse’ propagating in an inhomogeneous condensed state medium. The pulse expands as it travels. This expansion may be correlated to a material-characteristic dimension – such as the size of a grain or of a free path between scattering sites or of a domain – which is a random variable with a mean denoted as g_s . Moreover, we may ascribe to the propagation a loss constant which is proportional to g_s . The process derives from the fact that, for a relatively large number of scattering sites, it is possible to model the propagation media in terms of a repetitive electrical network. The model supports a Gaussian (bell shape) impulse response and defines g_s . Both theoretical and experimental (ultrasonic) results are provided. The experimental method is relatively fast to perform and the results are highly reproducible.     

Sequential Linear-Quadratic Method for Differential Games with Air Combat Applications

We present a numerical method for computing a local Nash (saddle-point) solution to a zero-sum differential game for a nonlinear system. Given a solution estimate to the game, we define a subproblem, which is obtained from the original problem by linearizing its system dynamics around the solution estimate and expanding its payoff function to quadratic terms around the same solution estimate. We then apply the standard Riccati equation method to the linear-quadratic subproblem and compute its saddle solution. We then update the current solution estimate by adding the computed saddle solution of the subproblem multiplied by a small positive constant (a step size) to the current solution estimate for the original game. We repeat this process and successively generate better solution estimates. Our applications of this sequential method to air combat simulations demonstrate experimentally that the solution estimates converge to a local Nash (saddle) solution of the original game.     

The minimum-area spanning tree problem

Motivated by optimization problems in sensor coverage, we formulate and study the Minimum-Area Spanning Tree (mast) problem: Given a set of n points in the plane, find a spanning tree of of minimum “area”, where the area of a spanning tree is the area of the union of the n−1 disks whose diameters are the edges in . We prove that the Euclidean minimum spanning tree of is a constant-factor approximation for mast. We then apply this result to obtain constant-factor approximations for the Minimum-Area Range Assignment (mara) problem, for the Minimum-Area Connected Disk Graph (macdg) problem, and for the Minimum-Area Tour (mat) problem. The first problem is a variant of the power assignment problem in radio networks, the second problem is a related natural problem, and the third problem is a variant of the traveling salesman problem.     

Electrodiffusion phenomena in C<Subscript>60</Subscript> thin films

As part of our ongoing research program to produce semiconductor devices based on C₆₀ thin films, we report here on our first attempts at the intercalative doping of C₆₀ thin films through the diffusion of metals. Two techniques were employed: (a) chemically induced counter electrodiffusion of Cu and I₂ into a C₆₀ matrix and (b) Au diffusion under the action of an external electric field.     

Einen einfachen und billigen Gasentwickelungsapparat

Ohne Zusammenfassung