Allowable exposure time

The accept and downgrade buttons are interlocked with a sensor device, so that a block must be scanned at least once before the block can be accepted and loaded out by the operator This function will however always be overruled by the programmed safety time limit, which will automatically reject and outload the block when the allowed exposure time has elapsed. 

Allowable exposure time (AET) The recommended maximum exposure time allowed for an operator in a workspace when subject to a physical or biological pollutant. 

Tests in waters and soils should ordinarily be allowed to run for extended periods in excess of 3 years, with removals of specimens in groups after different time intervals. A desirable schedule for any extended test in a natural environment is one in which the interval between successive removals is doubled each time. For example, the first removal would be after 1 year, the second after 3 years, and the third after 7 years, and so on. On the other hand, test periods should not be significantly longer than the process or exposure time of the end-use requirement. The testing of inhibitors for use if pickling or cleaning treatments should be of a period commensurate with the practical requirement which may be for only a few minutes. 

Time-Weighted Average (TWA)—An allowable exposure concentration averaged over a normal 8-hour... 

The application of the calculated reaction enthalpy allows us to estimate the kinetic chain length (approximately 30) and other kinetic data (reaction rate, final conversion, inhibition time) of the crosslinking reaction. The reaction rate (dx/dt) of this process is a function of the light intensity, the exposure time, of the thiol content of the system (see Fig. 1) and also of the photoinitiator used. The final degree of conversion of the double bonds is generally high (80 - 100 %). 

The application of a modified swelling test [3] allows us to estimate the network density as a function of exposure time and of the thiol content. Highest values are achieved in stoichiometric mixtures. 

In the field of imaging, present-day software should use mouse-driven or menu-selectable commands to control the camera and allow real-time image capture. The latter feature allows the users to monitor the image buildup and trigger the capture at the best moment. Temperature control and exposure times should... 

The time lag between exposure to a biological agent and the appearance of symptoms may serve as both a plus and a minus for terrorists. An incubation period allows terrorists time to attack and escape before an alarm is sounded. Conversely, an extended incubation period may diffuse the impact that the terrorists hope to achieve to bring attention to their causes (Tierno, 2002).2 The routes of exposure to biological agents vary, but may include ... 

The sample is placed on a photographic film which is protected from the light and allowed to remain in contact long enough for an adequate exposure. The exposure time is dependent upon the intensity of the radiation and can usually only be determined by trial and error. It is possible, however, to predict an approximate exposure time from the fact that a total emission of 107 beta particles per square centimetre is often required. 

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