Firms and market equilibria in a private ownership economy

Böhm V. Firms and market equilibria in a private ownership economy. Zeitschrift für Nationalökonomie. 1973;33(1-2):87-102

Existence of equilibria with price regulation

Böhm V. Existence of equilibria with price regulation. In: Hildenbrand W, ed. Contributions to mathematical economics: in honour of Gérard Debreu. Amsterdam: North Holland; 1986: 119-130

Quantitative Laser-Based Measurements and Detailed Chemical Kinetic Modeling of Nitric Oxide Concentrations in Methane-Air Counterflow Diffusion Flames

The formation and destruction of nitric oxide in diffusion flames remains a topic of particular relevance to practical applications. In the present work, the chemistry of NO in atmospheric methane-air counterflow diffusion flames is investigated by quantitative laser spectroscopic measurements and detailed chemical kinetic modeling. Highly resolved spatial NO concentration profiles have been obtained usinglaser-induced fluorescence (LIF), and the influence of temperature and collisions on the quantitative interpretation of LIF signals is described. Experimental nitric oxide profiles obtained in pure CH4-air flames and CH4-air flames seeded with NO and NH3 are presented. Comparisons are made with computations featuring a detailed chemical kinetic mechanism with 74 species and 506 reactions. It is shown that acceptable agreement is obtained, and the main areas of uncertainty are outlined. Thus, three current recommendations (GRI Mech. 2.11, Dean et al., and Lindackers et al.) for the prompt" NO formation channel CH+N2 are assessed. In apparent agreement with the theoretical study of Miller and Walch, the present work tentatively supports the determination of Dean et al., and it is suggested that the computer-optimized rate used in GRI-Mech. 2.11 is significantly (≈250%) too slow. It is further shown that methane diffusion flames differ from their premixed counterparts and that reaction channels such as CH with H2O and NO with HCCO exert a primary influence on computed results.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86749/1/Sick40.pd

Investigation of Spatially Resolved Light Absorption in a SI Engine Fueled with Propane/Air.

UV absorption in the combustion phase of spark-ignition engines strongly influences laser-induced-fluorescence measurements and flame-emission techniques because of the attenuation of a laser and/or signal light. This absorption was assessed with spatial, spectral, and temporal resolutions in an optically accessible research engine. Absorption was measured along a line for different crank-angle positions throughout the combustion phase of the engine by use of spectrally resolved transmittance measurements of both broadband illumination from a deuterium lamp and emission of laser-excited hot oxygen. Evaluating the spatial patterns of absorptivity revealed that no increased absorption can be attributed to the flame-front region and that homogeneous absorption cross sections for the whole burned-gas region can be assumed. The temporal change of absorption was shown to depend on the pressure effect with only negligible changes in absorption cross sections. Results obtained from the absorption measurements are applied for spatially resolved corrections of two-dimensional laser-induced-fluorescence measurements of NO concentration fields obtained under different operating conditions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86766/1/Sick35.pd

Influence of dome phosphor particle concentration on mid-power LED thermal resistance

The modern white mid-power LEDs usually contain phosphor particles encapsulated in silicone dome material. The particles convert the blue light emitted from the epitaxial layer and play significant role in thermal processes of LED packages. In this paper the influence of the phosphor particles concentration and effect of sedimentation on thermal resistance and junction temperature of mid-power LEDs are investigated. Thermal transient measurements, thermal imaging and finite element simulations are used. It is shown that the sedimentation of phosphor particles has an impact on both thermal resistance and junction temperature of mid- power LEDs. General trends for phosphor particles concentration effect on thermal properties of a mid-power LED are determined

Multidimensional Laser Diagnostic and Numerical Analysis of no Formation in a Gasoline Engine

Laser diagnostic imaging techniques were used to obtain detailed in-cylinder data from a commercial gasoline engine. Mean flowfields and turbulence intensities were acquired using particle imaging veloci-metry (PIV). Instantaneous quantitative NO-concentration fields were measured using planar laser-induced fluorescence (LIF). From experimental images of NO, also the flame propagation could be deduced. Combustion and NO formation were simulated with a 3-D computer code SPEEDSTAR. The overall agreement between experimental data and computational results is encouraging in general, with remaining issues to be solved. The mean flow is well predicted, whereas the prediction of turbulence quantities is less satisfactory. Calculated results for flame propagation are in good agreement with measurements. NO concentrations resulting from calculations are close to those measured, both in respect to their spatial distribution and absolute number densities. As could be expected, the highest NO concentrations are found in regions where combustion started earliest. Local concentrations of NO are found be up to 4 times higher than those in the exhaust. The comparison of experimental results with calculations clearly shows that, although the 3-D computer model can predict major features of the in-cylinder processes in agreement with measurements, details such as the exact flow pattern and flame development are difficult to capture and depend critically on some of the models parameters used.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86746/1/Sick38.pd