Rapid Track Research Articles

Fundamental Nonlinear Track Load-Deflection Behavior for Condition Evaluation

Locations of rapid track condition deterioration are typically well known to railway track engineers, although the cause and methods of improvement may be unclear. The rapid deterioration of these locations can be due to many factors such as poor conditions of the components (rail, tie, and ballast) or failure of any of the components or subgrade. The exact cause of the problem is generally unknown as attempts to maintain the track in acceptable condition (by surfacing or undercutting) are implemented. In conjunction with track geometry measurements, which help to identify poorly performing track locations, track load-deflection behavior can contribute to the knowledge of the cause of the problem, with an ultimate goal being identification of a cost-effective, long-term solution to improving the performance of the track. Fundamentals of track load-deflection behavior, how track behavior relates to performance, indices that can be used to determine suitable maintenance strategies, and the relation of these indices to actual track performance all contribute to the evaluation. As indications of the track load-deflection behavior, several track stiffness measurement techniques that have been proposed and tested are described. The goal is to clarify the need to measure track stiffness and to identify rational means of relating the data to track condition and, ultimately, to ensure maintenance, renewal, and safety.

Toward the further contributions of circulation

We are pleased to announce that Circulation will remain in its present Editorial office in Houston, Texas until June 30, 2004. The Scientific Publishing Committee of the American Heart Association has made this decision, and we are pleased to continue to be the stewards of Circulation . We renew our pledge to maintain a balanced journal, one that communicates the best of the research advances in clinical cardiovascular medicine and in basic science relating to the elucidation of mechanisms responsible for human cardiovascular diseases. We are also committed to rapid review, timely decisions, and the rapid presentation of these research advances. Our commitment to find better ways to communicate important cardiovascular research advances led to our determination to publish Circulation on a weekly basis, which we have now done for 22 months. Toward the goal of further enhancing Circulation ’s ability to publish some of the very best work in cardiovascular medicine, we now announce additional alterations in our publication policy. 1. We shall accept manuscripts for review on a Rapid Track …

Introduction of PMW and PEMW etchants for rapid and broad-energy range alpha track registration in ECE polycarbonate detectors

Introduction of PMW and PEMW etchants for rapid and broad-energy range alpha track registration in ECE polycarbonate detectors

Repetitive Track Seeking Algorithm for Optical Disk Drives

In order to achieve stable and rapid track seeking, a repetitive track seeking algorithm, which realizes highly accurate velocity control through velocity error integration, has been developed. Simulations and experiments show that the algorithm is effective in optical head velocity control. The algorithm reduces velocity error, compared with the conventional approach, so that the transient response at the seek end is greatly improved. The total seek time is reduced by adopting a reference velocity trajectory with larger deceleration rate, using this algorithm.

Rapid dilatation of the nephrostomy track using a new type of balloon catheter.

A new type of balloon catheter for rapid nephrostomy track dilatation from 3 to 10 mm is described. The balloon has a length of 10 cm, which means that the tract can be dilated in its entire length in one step. The catheter system is recommended for use, especially in patients previously not operated upon.

Observations of Charged-Particle Tracks in Solids

The characteristics of tracks produced by fission fragments have been studied by transmission electron microscopy in the following layer structure materials: molybdenite (MoS2), talc, clinochlore, jefferisite, and various micas including biotite, phlogopite, muscovite, and synthetic fluor-phlogopite. The measured track widths showed little correlation with the decomposition temperatures and it was concluded that the track formation cannot be described by a simple thermal spike model. The absence of any new rings or spots in the electron diffraction pattern of a heavily irradiated sample led to the conclusion that the tracks themselves consisted of a disordered region and not of a definable new crystalline phase. In many of the materials the tracks faded during observation in the beam. Although this fading could be eliminated by using a cold stage, it was not caused simply by the thermal instability of tracks; some materials which showed rapid track fading retained tracks to higher temperatures in external annealing experiments than did those in which no fading occurred. Annealing experiments also showed that tracks served to nucleate the high temperature decomposition of natural micas in a manner analogous to that previously reported for synthetic mica. The results of experiments in which Al absorbers were placed between a fission source and mica samples were interpreted as indicating that only particles with masses ≳ 30 are capable of forming visible tracks. This conclusion is consistent with the negative results of other irradiations in which mica samples were bombarded with 4-MeV alpha particles, 150-MeV oxygen nuclei, and 3-BeV protons. Experimental observations of the interaction of dislocations with tracks are also presented.