A theoretical analysis on the vibronic spectra with mass analyzed threshold ionization spectroscopy

We have theoretically studied the absorption vibronic spectra with the resonance two-photon (R2P) and non-resonance two-photon (NR2P) mass analyzed threshold ionization (MATI) spectroscopy. The theory uses the inverse Born-Oppenheimer approximation (IBOA) to establish a proper basis set. To analyze the MATI vibronic spectra, we have calculated the Franck-Condon factors involved in the vibronic transitions. Several experimental spectra are analyzed using this theory with emphasis on the importance of the resonance intermediate states. The long vibrational progression in a MATI spectrum can be partly attributed to the result of including the anharmonic correction in the calculated Franck-Condon factors. The experimentally observed isotope effect is also analyzed.     

Localizing impulse sources in an open space by time reversal with very few transducers

Localizing impulse point sources is a problem of major practical importance for numerous applications in security or equipment monitoring. It is difficult to solve when posed in a strongly congested propagation medium. This paper concerns the case where, in an open space, obstructing bodies are of a sufficient size and number to impede reception of certain direct paths from the source to the receivers. They produce reflected or diffracted paths. A low number of point receivers is used, 2-5, depending on the case. This fits practical constraints one meets in the field. The localization principle being time reversal, the aim is therefore to model the time reversed signal propagation from the receivers. From a direct signal obtained from measurements or computer simulations, the reversed propagation computation is made in the frequency domain or in the time domain. Despite the low number of receivers, which we would expect not to give good refocusing of the reversed wave, we are able in each case to localize the source with a conveniently chosen criterion, based on the time shortness of the signal. The advantage of this technique is its simplicity and speed: in a time formulation, a unique computation allows the localization. This result opens the way to economical measurement techniques for localizing impulse sources in congested or disturbed media, as long as a propagation model allowing integration of refraction, diffraction and reflection effects is available.     

Validation of inverse boundary condition design in a thermometry test bed

This study presents validation of an inverse boundary condition design analysis used in the design of an axisymmetric vacuum chamber with characteristics of a semiconductor rapid thermal processing (RTP) furnace. The vacuum chamber with heater is a thermometry test bed and is equipped with thermocouples and an instrumented silicon wafer to map the temperature field in the system. In order to model the physical system accurately, precise characterization of the system is essential. In the absence of any medium, radiative heat transfer is the dominant heat transfer mode. The radiative properties of the system's important components are measured and a numerical sensitivity study is conducted to understand the effects of property and model-based uncertainty introduced to the solution. The required power input for the heaters is estimated directly using inverse design so that specified thermal conditions across the silicon wafer are achieved at steady state. Through application of the estimated power distribution in the system, the design is validated by comparing the design goal and measured temperature distribution along the silicon wafer accounting for the uncertainties of the solution.     

Application of multi-phase particle swarm optimization technique to inverse radiation problem

The multi-phase particle swarm optimization (MPPSO) technique is applied to the inverse radiation problem in the present paper. The directional radiative intensities are served as the measurement data to estimate the radiative source term, optical thickness, scattering albedo, and phase function in one-dimensional semitransparent plane-parallel media by the inverse simulation. To check the performance and accuracy in retrieval, a comparison is presented between three PSO methods, i.e. the MPPSO, the standard PSO, and the Stochastic PSO. The results confirm the potential of the proposed approach MPPSO and show its effectiveness and superiority over the other two PSO algorithms. Furthermore, the effects of swarm size, searching space, phase change frequency, and velocity-reinitializing frequency on the convergence velocity and computational accuracy of MPPSO are also investigated.     

Ag-Na离子交换玻璃波导的折射率分布研究

用Ag-Na离子交换技术制备了玻璃平面波导.通过棱镜耦合技术测量了波导的模折射率,用反WKB方法拟合得到了平面波导的折射率分布为高斯分布.发现Ag-Na离子交换的扩散系数与交换时间有关,并且随着交换时间的增加而减小.使用随离子浓度变化的扩散系数求解扩散方程得到了玻璃内部Ag离子浓度分布,并通过SEM谱证实了求解的正确性;使用一次多项式模拟的方法求解折射率变化与Ag离子浓度变化之间的关系,得到了平面波导的折射率分布.与反WKB法只能获得多模离子交换平面波导的折射率分布相比,这种方法可以得到任意扩散时间下折射率变化与Ag离子浓度,可以获得单模平面波导的折射率分布.     

Characterization of the surface properties of heavy residues of oil distillation by inverse gas chromatography

Summary Heavy residues from the distillation of oils (SAFANYA) have been analyzed by inverse gas chromatography (IGC). The dispersive components of the surface energies of the residues could readily be determined. Acid/base characteristics could be appreciated using an original method developed in this Laboratory.     

Extracting more than a few eigenvectors from a dense real symmetric matrix: Optimal algorithms versus the architectural constraints of the FPS-X64

Ten widely available sets of routines, including HQRII, QCPE GIVENS and EISPACK 3, were evaluated for reliability, robustness, accuracy, speed, compactness, portability and simplicity. All were found lacking in one or more areas. Modified versions of the EISPACK routines TRED3, TQLRAT, TINVIT and TRBAK3 performed somewhat better. Changes to TINVIT were especially important for improved speed, accuracy and reliability. To achieve the maximum capabilities of the FPS-X64 series of computers access to table memory is required, but since the FORTRAN compiler does not allow this and there is no library support for the required operations, it was necessary to write three routines in APAL. The standard algorithm needs to be modified before full efficiency can be achieved for the back transformation.Operated for the US Department of Energy by Iowa State University under contract no. W-74-05-ENG-82. This work was supported by the Office of Basic Energy Sciences     

MULTIPLE PARAMETERS IDENTIFICATION PROBLEMS IN RESISTIVITY WELL-LOGGING

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A brownian motion model of return migration

This paper considers a continuous time, continuous state stochastic process to determine a theoretical model and empirical parameters for the probability distribution of remigration. A Brownian motion model is used for simplicity, with empirical findings drawn from a study of Israeli return migrants. A negative relationship between remigration (sojourn) time and the probability of return time is used to provide forecasts of remigration which can help governments who seek actively the return of their migrants to reach better decisions regarding the timing of their efforts.     

Inversion of the classical second virial coefficient

It is shown that, on the basis of some weak assumptions regarding the nature of the intermolecular pair potential, the classical second virial coefficient determines the potential uniquely.Research supported by NSF Grant GP-19881.