Electron beam density measurements in shock waves in argon

An electron beam technique was used to measure density profiles of strong shock waves in argon with high accuracy. The experimental results are compared with the results of theoretical models. Of the models that are available in enough detail for comparison, the best agreement with experiment is shown by the direct simulation Monte-Carlo method (Bird 1968), assuming an inverse 12th power molecular interaction force law. It is shown that the density maximum slope thickness is not sufficient for a detailed description of the shock wave structure

Transonic flow past an airfoil with condensation

In connection with investigations conducted to determine the influence of water vapor on experiments in wind tunnels, the question arose as to what changes due to vapor condensation might be expected in airfoil measurements. Density measurements on circular-arc airfoils aided by an interferometer in choked tunnels with parallel walls show that increasing humidity produces increasing changes in the flow field. The flow becomes nonstationary at high humidity. At the airfoil, however, the influence of the condensation is only felt, inasmuch as the shock bounding the local supersonic region moves upstream with increasing humidity while its intensity decreases. The density distribution upstream of the shock remains unchanged. Even if the flow becomes nonstationary in the vicinity of the airfoil, no changes occur at the airfoil

Complications of frontal defects

A case where the severe course of an orbital phlegmon led to a functionally and cosmetically poor condition is presented. Thirty-five years later, it was possible to achieve a satisfactory result through several operations performed with interdisciplinary cooperation. The orbit and forehead were reconstructed with porous polyethylene, thus ensuring a cosmetically good result. In two operations, the left eye was freed from its upward fixation through cicatrectomy and mobilization of the mucles, so that the eyes were straight again in the primary position. There is a limited binocular visual field. Binocular vision could be restored again after an interruption of 35 years

GEOS-20 m cable boom mechanism

The GEOS cable boom mechanism allows the controlled deployment of a 20 m long cable in a centrifugal force field. In launch configuration the flat cable is reeled on a 240 mm diameter drum. The electrical connection between the rotating drum and the stationary housing is accomplished via a flexlead positioned inside the drum. Active motion control of this drum is achieved by a self locking worm gear, driven by a stepper motor. The deployment length of the cable is monitored by an optical length indicator, sensing black bars engraved on the cable surface

A Walsh-Fourier approach to the circulant Hadamard conjecture

We describe an approach to the circulant Hadamard conjecture based on Walsh-Fourier analysis. We show that the existence of a circulant Hadamard matrix of order $n$ is equivalent to the existence of a non-trivial solution of a certain homogenous linear system of equations. Based on this system, a possible way of proving the conjecture is proposed.Comment: 8 page

A Study of Techniques for Calculating Motion Drive Signals for Flight Simulators

Development and evaluation of experimental test plan for solutions of motion drive problem in formation flying task with flight simulator