Surface Stress Meters

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. 

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.)...

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. 

Typically a BLEVE occurs after a metal container has been overheated above 538 °C (1,000 °F). The metal may not be able to withstand the internal stress and therefore failure occurs. The contained liquid space of the vessel normally acts as a heat absorber, so the wetted portions of the container are usually not at risk, only the surfaces of internal vapor spaces. Most BLEVEs occur when containers are less than 1/2 to 1/3 full of liquids. The liquid vaporization expansion energy is such that container pieces have been thrown as far as 0.8 km (1/2 mile) from the rupture and fatalities from such incidents have occurred up to 244 meters (800 ft.) away. Fireballs may occur at the time of rupture, that are several meters in diameter, resulting in intense heat exposure to nearby personnel. Fatalities due to burns from such incidents have occurred to personnel as much as 76 meters (250 Ft.) away from the point of rupture. 

The above mean is also referred to as the mean length diameter, dy, because it represents the sum of the length of the droplets divided by the total number of droplets. It is also possible to express the mean droplet size in a number of other ways (Table 2). Each of these mean sizes has dimensions of length (meters), but stresses a different physical aspect of the distribution, e.g., the average length, surface area, or volume. For example, the volume-surface mean diameter is related to the surface area of droplets exposed to the continuous phase per unit volume of emulsion, As ... 

Fig. 9 Data from the mooting station installed in the strait connecting the western and the eastern basins in October, 2005, Survey 5(2). The current meter and the level gauge at the mooring station were deployed at the depth of 4 m, about 1.5 m above the bottom in the deep channel at the western outlet of the strait. The meteorological station was installed at the northern bank of the strait, some 3 km north of the mooring. From top to bottom atmospheric pressure relative humidity zonal and meridional wind stress components zonal and meridional components of the current velocity surface level anomaly as derived from the pressure gauge...

Currents in the Sound are due to the tidal stream, to the estuarine circulation, and to wind stress acting on the water surface. Systematic surveys of the currents in the Sound have been made from time to time by the U.S. National Ocean Survey. Current meters have been placed in grid-pattern arrays for time intervals sufficiently long to reveal the principal tidal constituents of the current. Data obtained this way were used by G. A. Riley (1952, 1956) to describe the estuarine circulation of the Sound. The utility of these meter records in the study of sediment transport is limited because the observations were all made during the... 

Fio. 4. Each line segment in the upper diagram shows the net flow of water over a 12.4-hr tidal period. The current meters were at elevations of 0.88rf (A), 0.46water depth. The lower diagrams show resultant current vectors obtained from meter A (the one nearest the surface) and, for comparison, the resultant surface wind for the same time intervals. The surface water follows the wind stress closely the flow near the bottom is unrelated to the wind stress. The meters were set 7.4 km north of Eatons Neck. 

And finally, reinforced concrete can withstand beautifully all types of stresses, and this explains giant vertical and horizontal surfaces in modern constructions, such as the sky scrappers or several hrmdred meters taU TV towers. 

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