Thermal factor

TARGET VALUES FOR THERMAL FACTORS AN OVERVIEW OF INTERNATIONAL STANDARDS 373... 

The series of standards presented in this paper provides a useful package for assessment and design of HVAC systems and protective equipment to be used in moderate, cold, and hot environments. The standards may be used to estimate the optimal combination of environmental thermal factors that will provide comfortable or tolerable healthy working conditions. The standards may also be used to establish optimal work/rest schedules for environments where the working time must be limited owdng to strain on the human body. Several of these standards are being adopted as national standards in several countries. 

All deposits contain various ratios of scale and corrosion products, but often one material predominates, such as calcite or magnetite. These materials have different densities and thermal factors that influence the allowable deposit thickness or weight per unit area before cleaning becomes necessary. Practical allowances usually are between the limitations for each of these two materials. These allowances may be perhaps 50 to 100 mg/cm2 of surface area for lower pressure boilers and 25 to 50 mg/cm2 of surface area for higher pressure boilers. (For a more precise allowance, see the information below.)... 

The diffraction lines due to the crystalline phases in the samples are modeled using the unit cell symmetry and size, in order to determine the Bragg peak positions 0q. Peak intensities (peak areas) are calculated according to the structure factors Fo (which depend on the unit cell composition, the atomic positions and the thermal factors). Peak shapes are described by some profile functions 0(2fi—2fio) (usually pseudo-Voigt and Pearson VII). Effects due to instrumental aberrations, uniform strain and preferred orientations and anisotropic broadening can be taken into account. 

The symbols used are Vc, unit cell volume Bj, isotropic thermal factor of the yth atom. 

Diffraction patterns from thin polycrystalline Ge films were measured by the eleetron diffraetometer. After refinement of scale and thermal factors and corrections for the primary extinetion within the two-beam approximation, the parameters k (spherieal deeompression of valence eleetron shell) and multipoles P32- and P40 (anisotropy of electron density) were ealeulated (Table 4). The residual faetor R ealeulated from the experimental and theoretical amplitudes (the latter were ealeulated by the LAPW method, Lu Z.W., et al. Phys.Rev. 1993, B47, 9385) is 2.07% and proofs the high quality of the experimental. 

Slope-valley circulation, which is exclusively dependent on thermal factors, occurs as a result of spatially differentiated insolation (Fig. 4, [12]). During the day, slopes... 

It is easy to determine the environment of Pb in PbZrOs accurately, since PbZrOs is a well ordered compound. But many useful ferroelectric oxides, for instance well-known ferroelectric oxides, Pb(Zr,Ti)03 (PZT), are mixed ion systems in which the crystal sites are occupied by two or more different ions. In such systems it is more difficult to assess the state of Pb off-centering with accuracy using conventional crystallographic analysis, such as the Rietveld refinement. Local Pb displacements are often non-collinear, displaced in different directions from site to site. These local displacements will be observed indirectly only as artificially large thermal factors, and the average displace-... 

The spread of the explosion from the decomposed surface layer however depends on thermal factors, i.e. the heat liberated by the reaction is greater than that lost by self heating, conduction etc. The heat liberated during decomposition is sufficient to melt the surface of the azide and give rise to a reaction that will be self-supporting in the thermal sense. 

Due to the fact that mixing of the fuel and air is carried out in advance, the rate of reaction in a gaseous mixture is basically determined by thermal factors and by the kinetics of the chemical reaction. It is precisely the clarification of the role and laws of chemical reaction in a flame and in an explosion that constitutes our task. 

On the basis of the theory developed above we foresaw and realized experimentally (in Drozdov s work in our laboratory) a new kind of mixture which exhibits a significant dependence of the limit on the direction of propagation such mixtures do not contain hydrogen, and the diffusion mechanism in them facilitates combustion due to kinetic, rather than thermal factors. 

At higher temperatures, between —5° and 40°C, the reaction is essentially mechanochemical. At higher temperatures, participation of the thermal factor as a reaction activator is not ruled out. 

When temperature regulation is dependent solely on external jackets, a disproportional increase in nitration vessel capacity as compared with jacket surface occurs when the size of the machine is enlarged. Thus, if the volume is increased from 400 to 800 gallons, the heat-exchange area increases as the square and the volume as the cube of the expanded unit. To overcome this fault, internal cooling coils or tubes are introduced, which have proved satisfactory when installed on the basis of sound calculations that include the several thermal factors entering into this unit process. 

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