INDEX moisture, effect

The guarded hot-plate method can be modified to perform dry and wet heat transfer testing (sweating skin model). Some plates contain simulated sweat glands and use a pumping mechanism to deUver water to the plate surface. Thermal comfort properties that can be deterrnined from this test are do, permeabihty index (/ ), and comfort limits. PermeabiUty index indicates moisture—heat permeabiUty through the fabric on a scale of 0 (completely impermeable) to 1 (completely permeable). This parameter indicates the effect of skin moisture on heat loss. Comfort limits are the predicted metaboHc activity levels that may be sustained while maintaining body thermal comfort in the test environment. 

Materials Degradation Effects. Virtually all of the effects of S02 on materials are associated with its dissolution in surface moisture as the primary mechanism of deposition (19). Thus an appropriate environmental index for materials damage should include not only the average ambient S02 concentration but also a measure of the portion of time that the material surfaces are wet and thus receptive to S02 deposition. Sulfur in the atmosphere has an additional adverse affect on some materials through acidification of precipitation however, for both "dry" deposition of S02 and impact by acid precipitation, the primary damage mode is attack by dilute acids. 

Some unexpectedly complex liquid solid interactions have been detected and studied by ultrasonic impedance measurements (ultrasonic impedometry). Small amounts of water and alcohols have pronounced effects on the physical state of hydrophilic polymers specifically, the high frequency shear modulus and crystallinity index of a poly (vinyl alcohol) film increases with water content to a maximum before normal solution phenomena occur. These effects are attributed to the increased molecular order owing to water hydrogen bonded between polymer chains. The unusual effects of moisture on a novel poly(vinyl chloride)/plasticizer system and on hydrophilic polymers other than poly (vinyl alcohol) are also described. 

Fig. 55.—Effect of extrusion temperature on expansion (solid points), water absorption index (open points), water solubility index (stars), and viscosity at 50°C (triangles) of tapioca starch. (Initial moisture content was 22% on dry starch basis.) (Reprinted with permission of C. Mercier, R. Charbonniere, J. Grebaut, and J. F. de la Gueriviere, Cereal Chem., 57 (1980) 4-9.)...

Figure 14. Effect of moisture on protein dispersibility index (PDI) and lipoxygenase enzymes activity (LOX) during extrusion at 99° C.

Comfort is influenced by temperature, humidity, air velocity, radiant heat, clothing, and work intensity. Psychological factors may mso influence comfort, but their discussion is beyond the scope of this handbook. The reader is referred to Chap. 42 of the HVAC Applications volume of the A.S.H.R.A.E. Handbooks for a full discussion of the control of noise, which must also be considered in air-conditioning design. Figure 5 in Chap. 8 of the HVAC Fundamentals volume of the A.S.H.R.A.E. Handbooks relates the variables of ambient temperature, dew point temperature (or humidity ratio) to comfort under clothing and activity conditions typical for office space occupancy. It also shows boundary values for ET, the effective temperature index. This index combines temperature and moisture conditions into a... 

To face the problem of moisture, especially when the soil material is sensitive to moisture with a plasticity index (PI) <25, the lowering of the water table level is necessary to maintain it at a pre-determined depth below formation level (typically greater than 300 mm). This is achieved by the provision of an effective sub-drainage system or by raising the pavement structure to construct an embankment. 

Fig. 1. Effects of extrusion temperature on expansion ( ), breaking strength (+), viscosity at 50°C (a), water absorption index (O), and water-solubility index (x) of extruded products from corn grits. Initial moisture content before extrusion was 18.2% by weight (69).

---