Laboratory Technique

This thesis provides an innovative strategy for rail crack monitoring using the acoustic emission (AE) technique. The field study presented is a significant improvement on laboratory studies in the literature in terms of complex rail profile and crack conditions as well as high operational noise. AE waves induced by crack propagation, crack closure, wheel-rail impact and operational noise were obtained through a series of laboratory and field tests, and analyzed by wavelet transform (WT) and synchrosqueezed wavelet transform (SWT).

The Laboratory Companion, is a valuable reference guide for all those working in scientific laboratories. The range of information provided covers commonly used materials, equipment, and techniques found in most labs. Safety practices and safe procedures are constantly emphasized when discussing the proper methods of selecting, using, cleaning, and maintaining laboratory equipment (vacuum, compressed gases, measurement equipment, cryogenics, and other), as well as a thorough discussion of glassware.

The Laboratory Companion, is a valuable reference guide for all those working in scientific laboratories. The range of information provided covers commonly used materials, equipment, and techniques found in most labs. Safety practices and safe procedures are constantly emphasized when discussing the proper methods of selecting, using, cleaning, and maintaining laboratory equipment (vacuum, compressed gases, measurement equipment, cryogenics, and other), as well as a thorough discussion of glassware.

"One should rather go horne and mesh a net than jump into the pond and dive far fishes" (Chinese proverb) Recognizing the precise analytical question and planning the analysis according­ ly is certainly the first prerequisite for successful trace and ultratrace determina­ tions. The second prerequisite is to select the method appropriate to the analyti­ cal specification. The method itself consists of a set of available tools. The third prerequisite is that analysts and operators know the methods weH enough to enjoy challenging themselves as weH as the methods and are rewarded by the joy of high-quality data, fast and economical results and the conviction of having the analytical job under control. This skill is known among analysts or operators working with an exciting new and sometimes complicated analytical technique but is gradually lost on ce a technique becomes "mature" and a routine tool. Unfortunately, laboratory managers often do not allow sufficient training time for their analysts and technicians for "routine" techniques and thus miss an opportunity for motivating their co-workers and obtaining the full benefit of the equipment. Graphite furnace atomic absorption spectrometry (AAS) is one of the mature analytical techniques wh ich is seen as a routine method in most laboratories. More than 10,000 furnaces are operated in elemental trace and ultratrace analy­ ses in laboratories around the world today.