Resonant whirling of two-piece propshafts in rear-wheel-drive cars

Many modern cars with rear-wheel drives have a two-piece, rather than the traditional one-piece, props haft (or tail-shaft). The two-piece shaft requires less floor clearance, and hence a smaller floor tunnel, and does not suffer from the high-speed twisting resonances to which the one-piece shaft is susceptible. The two-piece shaft is, however, susceptible to a lower speed, high load (high torque) phenomenon in which the propshaft whirls with increasing amplitude until its restraining rubber bush is fully compressed in its mounting bracket, causing a thump sound. The whirling amplitude builds up periodically, so that a regular series of thumps is heard at a frequency of about 5 per second. The effect is very sensitive to the properties of the rubber bush and to its temperature. Different designs of bush are used by different makers, each with the purpose of minimizing both the whirling problem and the transmission of other vibrations to the car body. GMH has a particular design which it would prefer not to vary, because of retooling costs. It can however vary the properties of the rubber material itself. By trial and error it has achieved rubber properties which control the whirling problem to an acceptable level under normal conditions. GMH posed the question, to the MISG, of whether one can give theoretical guidelines for optimal rubber properties. This might lead to improved control of the whirling problem. It would also be useful for new and modified propshafts, if it could replace the tedious trial and error process previously employed. GMH were also anxious to gain a better understanding of the whirling phenomenon, and felt, with us, that a mathematical description of the phenomenon was a prerequisite for the study of the rubber properties. The thumping phenomenon is observed at both 40 and 80 kph approximately, although the phenomenon had a different quality at these two speeds

Think Different: Applying the Old Macintosh Mantra to the Computability of the SUSY Auxiliary Field Problem

Starting with valise supermultiplets obtained from 0-branes plus field redefinitions, valise adinkra networks, and the "Garden Algebra," we discuss an architecture for algorithms that (starting from on-shell theories and, through a well-defined computation procedure), search for off-shell completions. We show in one dimension how to directly attack the notorious "off-shell auxiliary field" problem of supersymmetry with algorithms in the adinkra network-world formulation.Comment: 28 pages, 1 figur

An 82 Inclination Debris Cloud Revealed by Radar

The statistical debris measurement campaigns conducted by the Haystack Ultrawideband Satellite Imaging Radar on behalf of the NASA Orbital Debris Program Office are used to characterize the long-term behavior of the small, low Earth orbit (LEO) orbital debris environment. Recent analyses have revealed the presence of a persistent LEO small debris cloud, which has no accompanying large component, cataloged by the U.S. Space Surveillance Network. This cloud, at an inclination of approximately 82 and below 1200 km in altitude does, however, correspond to the heavily trafficked region of space that has suffered several known, accidental collisions, e.g., Cosmos 1934 and Cosmos 2251. In this paper, we describe the observed cloud and model it using the NASA Standard Satellite Breakup Model. Key features of the cloud model, including source attribution and debris mass constraints, are presented to enable further observations and characterization

The advanced solar cell orbital test

The motivation for advanced solar cell flight experiments is discussed and the Advanced Solar Cell Orbital Test (ASCOT) flight experiment is described. Details of the types of solar cells included in the test and the kinds of data to be collected are given. The orbit will expose the cells to a sufficiently high radiation dose that useful degradation data will be obtained in the first year

Self-erecting reflector Patent

Antenna design with self erecting mesh reflecto

Mechanical chest-compression devices: current and future roles

Purpose of review: It is recognised that the quality of CPR is an important predictor of outcome from cardiac arrest yet studies consistently demonstrate that the quality of CPR performed in real life is frequently sub-optimal. Mechanical chest compression devices provide an alternative to manual CPR. This review will consider the evidence and current indications for the use of these devices. Recent findings: Physiological and animal data suggest that mechanical chest compression devices are more effective than manual CPR. However there is no high quality evidence showing improved outcomes in humans. There are specific circumstances where it may not be possible to perform manual CPR effectively e.g. during ambulance transport to hospital, en-route to and during cardiac catheterisation, prior to organ donation and during diagnostic imaging where using these devices may be advantageous. Summary: There is insufficient evidence to recommend the routine use of mechanical chest compression devices. There may be specific circumstances when CPR is difficult or impossible where mechanical devices may play an important role in maintaining circulation. There is an urgent need for definitive clinical and cost effectiveness trials to confirm or refute the place of mechanical chest compression devices during resuscitation

Non-Minimal String Corrections And Supergravity

We reconsider the well-known issue of string corrections to Supergravity theory. Our treatment is carried out to second order in the string slope parameter. We establish a procedure for solving the Bianchi identities in the non minimal case, and we solve a long standing problem in the perturbative expansion of D=10, N=1 string corrected Supergravity, obtaining the H sector tensors, torsions and curvatures.Comment: 19 pages, PACS number: 04.65.+