A survey on automatic pavement surface cracking detection systems

The development of new laser technologies in recent years has changed pavement data collection, opening the door to a fully automated approach. In this paper the application of the Pavement Surface Cracking Metric (PSCM), inspired by the Universal Cracking Indicator proposed by William Paterson in 1994, and developed by the ASTM E17 group is presented. The method uses quantitative definitions to ensure consistency of the results and eliminate the subjectivity associated with human ratings of pavement distresses. Multiple runs of pavement data have been collected on three asphalt sections to assess the repeatability and reproducibility of the method. The application of the Pavement Surface Cracking Index to convert the PSCM value, which is a physical property of the pavement, into a 100-0 score of the pavement section is also presented. Finally, the use of the PSCM to classify pavement distress and the inclusion of potholes and patching in the metrics are discussed.

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The Potentials of Scanning Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100101505 ◽

1968 ◽

Vol 26 ◽

pp. 352-353

Author(s):

A. V. Crewe

Keyword(s):

Salient Feature ◽

Secondary Emission ◽

Resolving Power ◽

X Rays ◽

Scanning Microscope ◽

Forming Process ◽

Additional Tool ◽

Detection Systems ◽

Conventional Microscope ◽

Present Information

If the resolving power of a scanning electron microscope can be improved until it is comparable to that of a conventional microscope, it would serve as a valuable additional tool in many investigations.The salient feature of scanning microscopes is that the image-forming process takes place before the electrons strike the specimen. This means that several different detection systems can be employed in order to present information about the specimen. In our own particular work we have concentrated on the use of energy loss information in the beam which is transmitted through the specimen, but there are also numerous other possibilities (such as secondary emission, generation of X-rays, and cathode luminescence).Another difference between the pictures one would obtain from the scanning microscope and those obtained from a conventional microscope is that the diffraction phenomena are totally different. The only diffraction phenomena which would be seen in the scanning microscope are those which exist in the beam itself, and not those produced by the specimen.

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Universal ESEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100149763 ◽

1993 ◽

Vol 51 ◽

pp. 786-787

Author(s):

G.D. Danilatos

Keyword(s):

Electron Microscope ◽

Scanning Electron Microscope ◽

High Vacuum ◽

Natural Extension ◽

Necessary Condition ◽

Environmental Scanning ◽

Detection Systems ◽

Small Gain ◽

Detection Medium ◽

Scanning Electron

The environmental scanning electron microscope (ESEM) has evolved as the natural extension of the scanning electron microscope (SEM), both historically and technologically. ESEM allows the introduction of a gaseous environment in the specimen chamber, whereas SEM operates in vacuum. One of the detection systems in ESEM, namely, the gaseous detection device (GDD) is based on the presence of gas as a detection medium. This might be interpreted as a necessary condition for the ESEM to remain operational and, hence, one might have to change instruments for operation at low or high vacuum. Initially, we may maintain the presence of a conventional secondary electron (E-T) detector in a "stand-by" position to switch on when the vacuum becomes satisfactory for its operation. However, the "rough" or "low vacuum" range of pressure may still be considered as inaccessible by both the GDD and the E-T detector, because the former has presumably very small gain and the latter still breaks down.

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Responding to Detection of Aerosolized "Bacillus anthracis" by Autonomous Detection Systems in the Workplace

PsycEXTRA Dataset ◽

10.1037/e548612006-001 ◽

2004 ◽

Keyword(s):

Bacillus Anthracis ◽

Detection Systems ◽

Autonomous Detection

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