Statistical analysis of synthetic earthquake catalogs generated by models with various levels of fault zone disorder

The stress release model, a stochastic version of the elastic rebound theory, is applied to the large events from four synthetic earthquake catalogs generated by models with various levels of disorder in distribution of fault zone strength (Ben-Zion, 1996) They include models with uniform properties (U), a Parkfield-type asperity (A), fractal brittle properties (F), and multi-size-scale heterogeneities (M). The results show that the degree of regularity or predictability in the assumed fault properties, based on both the Akaike information criterion and simulations, follows the order U, F, A, and M, which is in good agreement with that obtained by pattern recognition techniques applied to the full set of synthetic data. Data simulated from the best fitting stress release models reproduce, both visually and in distributional terms, the main features of the original catalogs. The differences in character and the quality of prediction between the four cases are shown to be dependent on two main aspects: the parameter controlling the sensitivity to departures from the mean stress level and the frequency-magnitude distribution, which differs substantially between the four cases. In particular, it is shown that the predictability of the data is strongly affected by the form of frequency-magnitude distribution, being greatly reduced if a pure Gutenburg-Richter form is assumed to hold out to high magnitudes.

Fatigue crack-growth from a circular notch under high-levels of biaxial stress

A series of experiments have been conducted on cruciform specimens to investigate fatigue crack growth from circular notches under high levels of biaxial stress. Two stress levels (Δσ₁= 380 and 560 MPa) and five stress biaxialities (λ=+1.0, +0.5, 0, −0.5 and −1.0; where λ=σ₂/σ₁ were adopted in the fatigue tests in type 316 stainless steel having a monotonic yield strength of 243 MPa. The results reveal that fatigue crack growth rates are markedly influenced by both the stress amplitude and the stress biaxiality. A modified model has been developed to describe fatigue crack growth under high levels of biaxial stress.

Spectrophone measurements in sulfur-hexafluoride

The optoacoustic signal generated by pulsed 10.6 c infrared radiation incident upon a test cell filled with gaseous SF6 has been analyzed in detail. The effects ofm icroscopic energy transfer from the absorbing vibrational degrees of freedom, spontaneous emission, thermal conduction, and acoustic wave propagation are included. This complete treatment explains the experimental observations including a negative pressure response following irradiation at low gas pressure.

Release of Sulfur and Chlorine during Cofiring RDF and Coal in an Internally Circulating Fluidized Bed

An internally circulating fluidized bed (ICFB) was applied to investigate the behavior of chlorine and sulfur during cofiring RDF and coal. The pollutant emissions in the flue gas were measured by Fourier transform infrared (FTIR) spectrometry (Gasmet DX-3000). In the tests, the concentrations of the species CO, CO2, HCl, and SO2 were measured online. Results indicated when cofiring RDF and char, due to the higher content of chlorine in RDF, the formation of HCl significantly increases. The concentration of SO2 is relatively low because alkaline metal in the fuel ash can absorb SO2. The concentration of CO emission during firing pure RDF is relatively higher and fluctuates sharply. With the CaO addition, the sulfur absorption by calcium quickly increases, and the desulfuration ratio is bigger than the dechlorination ratio. The chemical equilibrium method is applied to predict the behavior of chlorine. Results show that gaseous HCl emission increases with increasing RDF fraction, and gaseous KCl and NaCl formation might occur.

Release of Sulfur and Chlorine During Cofiring Rdf and Coal In An Internally Circulating Fluidized Bed

An internally circulating fluidized bed (ICFB) was applied to investigate the behavior of chlorine and sulfur during cofiring RDF and coal. The pollutant emissions in the flue gas were measured by Fourier transform infrared (FTIR) spectrometry (Gasmet DX-3000). In the tests, the concentrations of the species CO, CO2, HCl, and SO2 were measured online. Results indicated when cofiring RDF and char, due to the higher content of chlorine in RDF, the formation of HCl significantly increases. The concentration Of SO2 is relatively low because alkaline metal in the fuel ash can absorb SO2. The concentration of CO emission during firing pure RDF is relatively higher and fluctuates sharply. With the CaO addition, the sulfur absorption by calcium quickly increases, and the desulfuration ratio is bigger than the dechlorination ratio. The chemical equilibrium method is applied to predict the behavior of chlorine. Results show that gaseous HCl emission increases with increasing RDF fraction, and gaseous KCl and NaCl formation might occur.

Controllable group velocity of the probe light in a Lambda-type system with two fold levels

The group velocities of the probe laser field are studied in a A-type system where one lower state has two fold levels coupled by a control field. It is found that the interaction of double dark states leads to controllable group velocity of the probe field in this system. It can be easily realized, due to the interacting double dark resonances, that one of the group velocities at transparency positions is much slower than the other by tuning the control field to be off resonance. In particular, when the control field is on resonance. we can obtain two equal slow group velocities with a broader EIT width, which provides potential applications in quantum storage and retrieval of light. (c) 2005 Elsevier B.V. All rights reserved.

Number of phase levels of a Talbot array illuminator

The number of phase levels of a Talbot array illuminator is an important factor in the estimation of practical fabrication complexity and cost. We show that the number it) of phase levels of a Talbot array illuminator has a simple relationship to the prime number. When there is an alternative pi -phase modulation in the output array, the relations are similar. (C) 2001 Optical Society of America OCIS codes: 070.6760, 050.1950, 050.1980.