Thermal strain indices

If the clothing properties are not correctly matched to the heat balance, the body warns us that we are out of balance with thermal strain indicators. 

A relatively new initiative is the Universal Thermal Climatic Index (UTCI) (www. utci.org). Thermal strain is estimated with a thermal model based on input of climatic parameters. For any combination of air temperature, wind, radiation, and humidity... 

During exercise in the heat, sweat loss is the main mechanism to lose heat. Core temperature increases more when hypohydrated as compared to euhydrated subjects. Therefore, an international standard, ISO 7933, was based on the ratio between the amount of sweat that should be evaporated to stay in thermal equilibrium and the amount of sweat that can be evaporated maximally. This required sweat rate index (Ereq) standard is replaced with the Predictive Heat Strain Index developed by Malchaire (2006). This index is mainly used for the industry. Sometimes thermal strain is combined with thermal stress indicators in order to make an individual recommendation for performance limits (Epstein and Moran, 2006). 

Glass Type Thermal Coefficient of Expansion (0-300°C) xlO"7 Acm/cm/°C Strain Pont (=°C) Annealing Point (-°C) Softening Point ( °C) Working Point ( °C) Density (g/cm2) Refractive Index... 

Kamikawachi R, Possetti G, Muller M, Fabris J (2007) Influence of the surrounding refractive index on the thermal and strain sensitivities of a cascaded long period grating. Meas Sci Technol 18 3111-3116... 

Changes in the light propagation characteristics of a fiber due to temperature arise from (a) thermally induced length changes (b) the temperature dependence of the core refractive index, and (c) elasto-optic changes in the core due to thermally induced stress/strain changes. 

The performance of an extruder is determined as much by the characteristics of the feedstock as it is by the machine. Feedstock properties that affect the extrusion process inciude buik properties, meit flow properties, and thermal properties. Important buik flow properties are the buik density, compressibility, particle size, particle shape, external and internal coefficient of friction, and agglomeration tendency. Important melt flow properties are the shear and eiongational viscosity as a function of strain rate and temperature. The commonly used melt indexer provides only limited information on the meit viscosity. Important thermal properties include the specific heat, the glass transition temperature, the crystalline melting point, the latent heat of fusion, the thermal conductivity, the density, the degradation temperature, and the induction time as a function of temperature. 

For strain, subscript (j = 1,2,3,4,5,6) is used. The first three represent the normal strains in the first (fibre axis), second, third directions, respectively, the latter three being the three shear strains, respectively. The strain s of an optic fibre may be contributed by either thermal expansion or stress, hence the symbol s is used for the optic fibre strain induced by stress only. The refraction index n is related to both temperature T and strain g, therefore ... 

Type of Silica Tradenames Total Cation OH Cl UV Trans. Impurity Impurity Impurity (50% Trans.) (ppm) (ppm) (ppm) (nm) Bubbles and Thermal Exp. Inclusions Coefficient (max S / (cm/cmxlO ) cubic in.) Strain (nm/cm) Refractive Index n(d) Index Dispersion Homogeneity v(d) (XIO ) Density (g/cc)... 

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