Local analyses temperature

The cooling effect of the channel walls on flame parameters is effective for narrow channels. This influence is illustrated in Figure 6.1.3, in the form of the dead-space curve. When the walls are <4 mm apart, the dead space becomes rapidly wider. This is accompanied by falling laminar burning velocity and probably lowering of the local reaction temperature. For wider charmels, the propagation velocity w is proportional to the effective flame-front area, which can be readily calculated. On analysis of Figures 6.1.2b and 6.1.3, it is evident that the curvature of the flame is a function of... 

Xu, L. X., Chen, M. M., Holmes, K. R., and Arkin, H 1993, Theoretical Analysis of the Large Blood Vessel Influence on the Local Tissue Temperature Decay after Pulse Heating, ASME Journal of Biomechanical Engineering, 115 175-179. 

In the present analysis, fluid properties are taken as constant and uniform, except for the viscosity. The flow is presumed to be laminar, with negligible inertia effects. The fluidity (reciprocal viscosity) is represented by a polynomial in tenns of position across the film, with coefficients related to the local film temperature distribution. Use of this procedure permits a closed-form expression for the local lineal mass flux, albeit there is some difference between a fluidity profile which would everywhere correspond to the temperature profile and one which is thus approximated. 

SThM was carried out in the laboratory of H. Pollock and A. Hammiche in the Physics Department of the University of Lancaster, Lancaster, UK using a modified Topometrix Explorer SPM (Topometrix Corporation, Santa Clara, CA). The microscope uses a small Wollaston wire, bent and etched to form a contact mode AFM tip with a nominal radius of about 200 nm. The tip is used both as a heat source and a heat sensor. A second, reference, tip is held in air in close proximity to the sample for differential measurements. The heat to the tip can be modulated and the material response to the modulated heating can be monitored during imaging via lock-in techniques. For the work described here the microscope was operated in three imaging modes (1) constant deflection (for topography) (2) constant temperature (DC) and (3) modulated temperature (AC). In an unscanned mode, the tip can be positioned on the surface for local differential thermal analysis (DTA) or local modulated temperature-DTA and local thermomechanical (TMA) measurements (4,22). 

Thermal Properties. Spider dragline silk was thermally stable to about 230°C based on thermal gravimetric analysis (tga) (33). Two thermal transitions were observed by dynamic mechanical analysis (dma), one at —75° C, presumed to represent localized mobiUty in the noncrystalline regions of the silk fiber, and the other at 210°C, indicative of a partial melt or a glass transition. Data from thermal studies on B. mori silkworm cocoon silk indicate a glass-transition temperature, T, of 175°C and stability to around 250°C (37). The T for wild silkworm cocoon silks were slightly higher, from 160 to 210°C. 

For the analysis heat and mass transfer in concrete samples at high temperatures, the numerical model has been developed. It describes concrete, as a porous multiphase system which at local level is in thermodynamic balance with body interstice, filled by liquid water and gas phase. The model allows researching the dynamic characteristics of diffusion in view of concrete matrix phase transitions, which was usually described by means of experiments. 

That some enhancement of local temperature is required for explosive initiation on the time scale of shock-wave compression is obvious. Micromechanical considerations are important in establishing detailed cause-effect relationships. Johnson [51] gives an analysis of how thermal conduction and pressure variation also contribute to thermal explosion times. 

In industrial ventilation the majority of air velocity measurements are related to different means of controlling indoor conditions, like prediction of thermal comfort contaminant dispersion analysis adjustment of supply airflow patterns, and testing of local exhausts, air curtains, and other devices. In all these applications the nature of the flow is highly turbulent and the velocity has a wide range, from O.l m in the occupied zone to 5-15 m s" in supply jets and up to 30-40 m s in air curtain devices. Furthermore, the flow velocity and direction as well as air temperature often have significant variations in time, which make measurement difficult. 

Any experimentally measured set of (at, ti) values for an isothermal reaction contains errors including (inter alia) inaccuracies in yield and time determinations and departure of temperature from the constant value temporarily and locally. In any quantitative kinetic analysis, several interdependent factors must be considered. 

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