Scanning information sources

Scan information sources (dials, chart recorders, etc.). If the pattern of indicators is very familiar, the worker will probably immediately branch to the Execute Actions box (via the thin arrow) and make the usual response to this situation (e.g., pressing the alarm accept button if the indications suggest a nonsignificant event). 

For example, if a worker turns on a stirrer in a reactor, he or she may use a local or control room indicator to verify that current is flowing to the agitator motor. Errors may arise at several points in the input process. At the sensory stage, there may be so many sources of information that the worker may be unable to scan em all in the time available. This can be a particular problem when a large number of alarms occur following a major process disturbance. 

We wish to repeat here the warning at the end of Section 9.9. A point source when needed is a fine thing when not needed, it may give misleading information unless the sample is uniform in composition, as most are not. Scanning with a microprobe will give information on average composition. 

MS-MS is a term that covers a number of techniques in which two stages of mass spectrometry are used to investigate the relationship between ions found in a mass spectrum. In particular, the product-ion scan is used to derive structural information from a molecular ion generated by a soft ionization technique such as electrospray and, as such, is an alternative to CVF. The advantage of the product-ion scan over CVF is that it allows a specific ion to be selected and its fragmentation to be studied in isolation, while CVF bring about the fragmentation of all species in the ion source and this may hinder interpretation of the data obtained. 

In recent years, high-resolution x-ray diffraction has become a powerful method for studying layered strnctnres, films, interfaces, and surfaces. X-ray reflectivity involves the measurement of the angnlar dependence of the intensity of the x-ray beam reflected by planar interfaces. If there are multiple interfaces, interference between the reflected x-rays at the interfaces prodnces a series of minima and maxima, which allow determination of the thickness of the film. More detailed information about the film can be obtained by fitting the reflectivity curve to a model of the electron density profile. Usually, x-ray reflectivity scans are performed with a synchrotron light source. As with ellipsometry, x-ray reflectivity provides good vertical resolution [14,20] but poor lateral resolution, which is limited by the size of the probing beam, usually several tens of micrometers. 

Product-ion Selecting mtz Scanning To obtain structural information by CID of ions produced in the source... 

Modern spectrometers only require electron beam currents in the range 0.1 lOnA and hence probe sizes of 20-200 nm may be readily achieved with thermionic sources and 5-15 nm with a FEG. Spatially resolved compositional information on heterogeneous samples may be obtained by means of the Scanning Auger Microprobe (SAM), which provides compositional maps of a surface by forming an image from the Auger electrons emitted by a particular element. 

A wide variety of possible sources of published information has been scanned to ensure maximum coverage. Primary sources have largely been restricted to journals known to favour or specialise in publication of safety matters, and the textbook series specialising in synthetic and preparative procedures. 

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