An initial investigation on the potential applicability of Acoustic Emission to rail track fault detection.

In light of recent accidents in the rail industry, the assessment of the mechanical integrity of rail-track is of vital importance. This encompasses the integrity of the track due to rolling contact fatigue and surface wear. Whilst numerous techniques are employed for crack detection, several defects have clearly been missed. In Europe, more than 100 rails are broken each year and rail maintenance costs within the European Union is estimated at 300-million Euros annually [Inst Mech Engrs 216 (2001) 249]. The derailment of a train at Hatfield in October 2000 is a tragic example of a fractured rail going undetected. This paper presents an experimental study on the applicability of Acoustic Emissions (AE) for rail-track defect diagnosis. An experimental test- rig was employed for this programme. This allowed for a surface defect to be seeded onto the test-rig. The investigation presented is part of an on-going attempt to develop the non-destructive technique of AE for assessing the surface integrity of rail-track. The AE technique is not new but the application in this particular instance is unique. It is concluded that the AE technique offers a complementary tool for rail track defect detection

High-Impact Charm Physics at the Turn of the Millennium

I review the sensitivities achieved by and projected for fixed-target charm experiments in CP violation, flavor-changing neutral-current and lepton-number-violating decays, and mixing, and I describe the Charm2000 experiment intended to run at Fermilab in the Year ~2000. If approved, Charm2000 will in many of these areas exceed the sensitivities projected for a Tau/Charm Factory, but the Tau/Charm Factory retains certain qualitative advantages.Comment: 23 pages, 3 Postscript figures (minor revisions, mostly typographical, relative to version of 8/31

Controlling single-photon detector ID210 with bright light

We experimentally demonstrate that a single-photon detector ID210 commercially available from ID Quantique is vulnerable to blinding and can be fully controlled by bright illumination. In quantum key distribution, this vulnerability can be exploited by an eavesdropper to perform a faked-state attack giving her full knowledge of the key without being noticed. We consider the attack on standard BB84 protocol and a subcarrier-wave scheme, and outline a possible countermeasure.Comment: 6 pages, 5 figure

Monitoring of lubricant film failure in a ball bearing using ultrasound

A lubricant-film monitoring system for a conventional deep groove ball bearing (type 6016, shaft diameter 80 mm, ball diameter 12.7 mm) is described. A high-firequency (50 MHz) ultrasonic transducer is mounted on the static outer raceway of the bearing. The transducer is focused on the ball-raceway interface and used to measure the reflection coefficient of the lubricant in the "contact" ellipse between bearing components. The reflection coefficient characterizes the lubricant film and can be used to calculate its thickness. An accurate triggering system enables multiple reflection measurements to be made as each lubricated contact moves past the measurement location. Experiments are described in which bearings were deliberately caused to fail by the addition of acetone, water and sand to the lubricant. The ultrasonic reflection coefficient was monitored as a function of time as the failure occurred. Also monitored were the more standard parameters, temperature and vibration. The results indicate that the ultrasonic measurements are able to detect the failures before seizure. It is also observed that, when us,ed in parallel, these monitoring techniques offer the potential to diagnose the failure mechanism and hence improve predictions of remaining life