Energy concentration

Free-energy-concentration diagrams have been used in the study of the thermodynamic influence on the non-stoichiometry of the solid titanium carbide deposited from H2-CH4-TiCl4 gas mixtures at 1 900 K. The authors show how, from the partial pressure measurements of Ti vapour over a range of... 

Fig. 7.86 Frec-energy-concentration curves for Fe(,)-Zn(/) at 505 C under (a) equilibrium conditions, (b) pressure conditions and (c) galvanising conditions (after Mackowiak...

If these large energy concentrations meet a flaw in the rubber, the resulting tearing energy will increase the flaw at each pass until a rubber particle is detached. This is essentially the mechanical basis of the abrasion process. 

HINT In order to remember the nine diagnostic symptoms for a major depressive episode, learn the following mnemonic Depression = SIG E CAPS (depression, sleep, interest, guilt, energy, concentration, appetite, psychomotor, suicide). 

Figure 1. Variations in the hourly mean alpha-energy concentration during an integrating radon gas measurement of three weeks The alpha-energy concentration calculated from the radon level (4860 Bq/m3) and the typical equilibrium factor (0.45) is also given.

An equilibrium factor of 0.35, derived from measurements made during the local surveys, has been assumed to typify conditions in UK dwellings. This value has been used to convert the average radon concentrations measured in the national survey to potential alpha-energy concentration of radon decay-products. On average, persons in the UK spend 75% of their time in their homes and 15% of their time elsewhere indoors (Brown, 1983). The occupancy factor of 0.75, together with an equilibrium factor of 0.35, results in an annual exposure of 1.3 10"5 J h m"3 (0.0037 Working Level Months,... 

Radon concentrations were measured by use of calibrated Lucas scintillation flasks, while radon and thoron daughters and the resulting potential alpha energy concentration (PAECj were determined using filter samples (Thomas, 1972) and a continuous electrostatic precipitator (Andrews et al., 1984). The radon daughter positive... 

The exposure rate characteristic for this atmosphere is then given by the potential alpha energy concentration (PAEC) Ep... 

It has been demonstrated that it is possible to lower the level of airborne radon progeny by filtering and/or expose the air to an electric field. If the radiological risk is measured by the potential alpha energy concentration (PAEC) or exposure rate, for instance expressed in J m 3 or WL, the level may be lowered to about 10-20 % of the value in untreated air, while the reduced level may only be about 40-50 % of the untreated one if the average dose to a certain part of the respiratory tract, for instance expressed in Gy year 1, is considered. 

The same kind of optimization has been performed for the thoron daughters. In the calculations the sampling period was set at 30 min and the first decay time interval is started after the decay of the radon daughters (270 min). For a total measurement time of 16 hours the optimized MMC of Pb-212 and Bi-212 are respectively 0.02 Bq/m and 60 Bq/m (270-370 min, 540-960 min). Better results for Bi-212 are obtained with only one decay time interval and an estimation of the ratio of Pb-212 to Bi-212 out of the removal processes (ventilation and deposition of the attached thoron daughters). The influence of the removal rate on the potential alpha energy concentration is small. For the decay interval (270-960 min) the MMC of Pb-212 is 0.014 Bq/m, assuming the sum of the removal rates to be 0.6+0.5/h. 

Continuous measurements of the potential alpha energy concentration of the radon decay products were made with a Continuous Working Level Monitor (WLM-300) (EDA Instruments Inc., Toronto). 

A better way to express the activity of the radon decay products is as the Potential Alpha Energy Concentration (PAEC). This quantity incorporates the deposition of energy into the air and is expressed as MeV/nr... 

First, let s look at what current lasers and masers do. Lasers vary in size from single atoms, or submicroscopic size, to lasers as big as tall buildings. Well, the single atoms in small lasers produce fantastically small amounts of power - let s say, 10 16 watts. The big ones have produced as much as 10+16 watts - that is, ten million billion watts, more than we have from any other kind of source. Now, that lasts for a short time, because it would be too expensive to have it on all the time, of course. Nevertheless, it s very powerful, and that great power produces an intensity which allows us to study and to understand new states of matter with very high energy concentration. 

Energy concentration is even more important than power. With a laser, 10+15 or 10+16 watts can be concentrated in an area about the size of one wavelength, so we have maybe 10+23 watts per square centimeter. That s a fantastic concentration of power, which produces new kinds of conditions and opens up some new science. 

In the calculations presented so far, all electrons have been correlated. However, chemical reactions involve mainly the valence electrons, leaving the core electrons nearly unaffected. It is therefore tempting to correlate only the valence electrons and to let the core orbitals remain doubly occupied. In this way, we avoid the calculation of the nearly constant core-correlation energy, concentrating on the valence correlation energy. The freezing of the core electrons simplifies the calculations as there are fewer electrons to correlate and since it enables us to use the cc-pVXZ basis sets rather than the larger cc-pCVXZ sets. 

The exact method by which fracture occurs is not known, although it is suggested by I>r r i i 51 that the compressive force produces small flaws in the material. If the energy concentration exceeds a certain critical value, these flaws will grow rapidly and will generally branch, and the particles will break up. The probability of fracture of a particle... 

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