Stress meters

Material required Intact leaves and Portable Plant Stress Meter (BioMonitor S.C.I.AB, Sweden). 

Chlorophyll fluorescence kinetics of leaves (adaxial side) and needles (upper surface) were measured at room temperature by a Plant Stress Meter (BioMonitor AB S.C.I., UmeS, Sweden). The ratio Fv/Fm was used as a measure of the photochemical efficiency of photosystem li. The plants were dark adapted for at least 45 min prior to fluorescence measurements. 

The photochemical efficiency of photosystem II was measured as the Fv/Fm ratio using a Plant Stress Meter (Bio Monitor S.C.I. AB, Ume, S) (6).The photon flux density of the actinic light was 400 pmol m s and the time of excitation was 5 s. The needles were dark adapted at room temperature for 30 min before measuring. 

The reinforcement stress meter was installed in series with the main reinforcing steel bar in the base plate-finished on March 7, 2012-monitoring results are shown in Figure 9. 

A portable heat stress meter or monitor may also be used to integrate and calcnlate the WBGT information. Combined with information on the work being performed, the heat stress meter can determine the duration for which an individual can work safely in a hot environment. 

The REED SD-2010 Heat Stress Meter features a datalogger with 2GB SD memory card (optional) Air Temp. 0 to SOT WBGT 0 to 59°C Black Globe Temp. 0 to 80°C Wet Bulb Temp. -21.6 to 50.0°C Dew Point Temp. -25.3 to 48.9°C and Humidity Range 5 to 95% RH. Reed Instruments, www.reedin-struments.com/reedinst.html. Circle 263... 

The quantitative determination of stress requires a calibrated relative retardation S to compensate the measured one S (S + S = 0), and we shall use from here onward the term compensator . As stated above, generally we measure a stress difference that reduces to one component only when the other one is null. This assumption is valid, at the edge of a glazing (edge stress meter), and when the light beam propagates at the surface of the glass sheet (surface stress meter). Both instruments are described in the two next sections. 

Figure 11.9 (a) Edge stress meter principle www.sharplesstress.com/.) (c) Strainoptics Inc. with a Senarmont compensator, (b) Sharpies edge stress meter. (Photograph courtesy of edge stress meter. (Photograph courtesy Strainoptics Inc., www.strainoptics.com.)... 

Another important apparatus is the surface stress meter that allows measurement of the surface stresses (since the stress component normal to the surface is null). Using the mirage effect due to the tin concentration gradient at the tin side... 

Figure 11.12 Surface stress meter, Strainoptics Inc. apparatus (GASP (Photograph courtesy of Strainoptics Inc., www.strainoptics.com.)...

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