Optimization of a tracer-based PLIF diagnostic for simultaneous imaging of EGR and temperature in IC engines

A tracer-based planar laser-induced fluorescence (TB-PLIF) imaging diagnostic using 3-pentanone has been optimized for use in IC engines. The diagnostic utilizes dual-wavelength excitation of 3-pentanone in the ultraviolet to make simultaneous measurements of exhaust gas residual mole fraction and temperature. A merit function based optimization of the diagnostic precision was performed which allowed for selection of optimal excitation wavelengths for the conditions of interest. Optimized system performance was validated in a motored optical engine over a wide range of in-cylinder temperatures and pressures. In-cylinder results verify the utility of the uncertainty estimates. Differences in magnitude between the estimated and measured precision were determined to be due to errors in parameter values used in the calculations. The observed 2.1% temperature precision at a temperature of 600 K was compared with previous TB-PLIF temperature measurements and shown to be approximately a factor of 2 better than previous results.     

Thermoelectric efficiency and compatibility

The intensive reduced efficiency eta(r) is derived for thermoelectric power generation (in one dimension) from intensive fields and currents, giving eta(r)=(E x J) divided by (- inverted Delta)T x J(S). The overall efficiency is derivable from a thermodynamic state function, Phi=1 divided by u + alphaT, where we introduce u=J divided by kappa (inverted Delta)T as the relative current density. The method simplifies the computation and clarifies the physics behind thermoelectric devices by revealing a new materials property s=(sqrt[1+zT]-1) divided by (alphaT), which we call the compatibility factor. Materials with dissimilar compatibility factors cannot be combined by segmentation into an efficient thermoelectric generator because of constraints imposed on u. Thus, control of the compatibility factor s is, in addition to z, essential for efficient operation of a thermoelectric device, and thus will facilitate rational materials selection, device design, and the engineering of functionally graded materials.     

Effect of heat treatment on the magnetic and magnetoelastic properties of cobalt ferrite

The influence of different heat treatments on the magnetic and magnetoelastic properties of highly magnetostrictive CoFe₂O₄ has been investigated. The first order cubic anisotropy coefficient, coercive field, magnetostriction and high strain sensitivity were observed to decrease as the heat treatment temperature increased. The saturation magnetization of the samples on the other hand increased with increase in heat treatment temperature. These changes were not accompanied by any observable changes in crystal structure or composition and are indicative of migration of Co²⁺ from the octahedral sites (B-sites) to the tetrahedral sites (A-sites) and Fe³⁺ from the A-sites to the B-sites of the spinel structure. Different distributions of the cations at the two distinct lattice sites can strongly affect the magnetic and magnetoelastic properties of these materials.     

Evidence for the ground-state resonance of 26O

Evidence for the ground state of the neutron-unbound nucleus (26)O was observed for the first time in the single proton-knockout reaction from a 82 MeV/u (27)F beam. Neutrons were measured in coincidence with (24)O fragments. (26)O was determined to be unbound by 150(-150)(+50) keV from the observation of low-energy neutrons. This result agrees with recent shell-model calculations based on microscopic two- and three-nucleon forces.     

Dependence on the scattering angle of the electron temperature and electron density in thomson-scattering measurements on an atmospheric-pressure plasma jet

Electron temperature and electron density measurements were made in an atmospheric-pressure argon plasma jet by line-shape analysis of Thomson-scattered laser light. The dependence of electron temperature and electron density on the scattering angle was investigated. Measurements were made using incident laser wavelengths of 532 and 355 nm. At 532 nm, the electron-ion collision frequency exceeds the Landau damping rate for shallow scattering angles, and the electron plasma wave resonance structure in the Thomson line shape is broadened. This resulted in dramatic increase in the apparent electron temperature as a function of decreasing scattering angle. At 355 nm, collisions do not affect the Thomson line shape. In this case, an angular dependence of the measured electron temperature is not expected and was not observed. Data taken at 532 nm at larger scattering angles are consistent with the 355-nm results, and show that the electrons are not in thermodynamic equilibrium with the heavy particles.     

Synthesis, structure, and electronic calculations of group VII substituted pyridazines

A series of 5,6-fused ring cyclopentadienyl tricarbonyl manganese and rhenium complexes, [M(CO)₃{η ⁵-1,2-C₅H₃(1,4-(R)₂N₂C₂}] (2a–3d) were isolated by employing an off-metal ring closure route. Reacting thallium cyclopentadienide (Cp) salts (1a–d) with [MBr(CO)₅] (M = Mn, Re) provided pyridazyl complexes (2a–3d) in high yield (75–99 %). Spectroscopic characterization (NMR, IR, MS) confirmed the identity of the desired organometallic pyridazines. The off-metal synthetic pathway employed did improve upon the isolation of these complexes as compared to previously reported routes. The molecular and electronic structure of complexes 2a–3d and their optimal energy structures have been characterized with quantum chemistry calculations. Vibrational frequencies calculated were compared to their experimental counterparts. The excited state calculations predict that the dominant low-energy transition involves a ligand-to-metal charge transfer.