Laser induced long-lived emission spectra of laser dyes in rigid glasses at 77 K

Phosphorescence decay of 3-(2′-N-methylbenzimidazolyl)-7-N, N-diethylaminocoumarin; 2,3,5,6-1H, 4H-tetrahydro-8-methylquinolizino-〈9, 9a, 1-gh〉 coumarin; 2,3,5,6-1H, 4H-tetrahydro-8-trifluormethylquinolizino-〈9,9a,1-gh〉 coumarin; 9(10H)-acridone; 9-aminocridine hydrochloride, 1-hydrate and 2-(4-biphenylyl)-5-(4-t-butylphenyl)-1,3, 4-oxadiazole dyes in EPA glass at 77 K have been recorded using N₂ laser. The results were used to determine lifetimes. Emission intensities from the first two dyes have been examined in relation to dye concentration and excitation intensity. The results are discussed.     

Bayesian analysis of fixed-interval preventive-maintenance models

This article develops methods for making accurate decisionswhen scheduling preventive maintenance in systems where inter-eventtimes can be modelled by a delayed renewal process or delayedalternating renewal process. A practical application, relatingto the reliability and maintenance of a relatively low-levelcomponent (valve) in a continuous-process industry over a periodof six years is presented to demonstrate and compare the differentapproaches. Our analyses indicate a cost-effective recommendationfor maintenance practice in this context. Our main thrust relates to the use of Bayesian methodology inorder to obtain rational, admissible decisions. Particular advancesover previous research allow for informative prior distributions,better approximations which lead to improved accuracy, non-negligibledowntimes, and general lifetime distributions. General analyticsolutions are sought for the simpler models, in order to achieveaccuracy and insight. The resulting integrals can only be solvedto give an infinite series and one approximation to the requiredsolution is obtained by truncating this series. Two other approximationsare developed, based on expansions of the prior predictive andlog-posterior distributions. A simulation approach is also developed to include prior informationand hence provide alternative approximations to these optimaldecisions. With exponential lifetime distributions, the relevantposterior lifetime distributions are non-central Pareto. Thissimulation is simple to program, compared to the approximations,but requires more computing time. It is accurate and extendseasily to situations involving greater complexity. We considertwo such extensions, the inclusion of downtimes and Weibulllifetime distributions.     

A note on Sheppard's corrections for grouping and maximum likelihood estimation

Sheppard's corrections for grouping can, in the case of an underlying normal distribution, be interpreted as a first step to the solution of the maximum likelihood equations which incorporate the grouping problem. This result of Lindley (for the univariate) and Haitovsky (for the bivariate) is generalized to the multivariate normal distribution, making use of recent results in matrix algebra. Also, formulae concerning the efficiency lost in grouping are generalized to the multivariate case.     

Some multivariate linear regression testing problems with additional observations

In an earlier paper, the present author ([6], Calcutta Statist. Assoc. Bull.28, 47–56) proposed a similar test for a mean testing problem with additional observations on a set of correlated auxiliary variables. This idea has been extended here to cover some multivariate linear regression testing problems with the same type of additional observations on a set of correlated auxiliary variables.     

The Role of Momentum Transfer in Welcher–Weg Experiments

In the present analysis of Welcher–Weg (WW) measurements, momentum transfer effects are taken into account. Although the WW apparatus that determines which-way might not include any momentum transfer, there is a momentum transfer to the macroscopic entangled parts of the system (beam-splitter and mirrors in Mach–Zehnder interferometer or macroscopic double-slit wall in 2-slit experiments). We show how a measurement in one location (the WW apparatus) influences the wavefunction at another location (the beam-splitter or 2-slit wall) and fixes momentum at that second place, exactly as that of the EPR effect.     

Heterogeneous triplet-triplet annihilation of erythrosine and anthracene molecules on a fractal anodized aluminum surface

We have studied exchange resonance processes of homogeneous triplet-triplet annihilation and heterogeneous triplet-triplet annihilation for erythrosine and anthracene molecules on an anodized aluminum surface over a broad temperature range. We have shown that the kinetics of the considered processes are determined by the dimensionality of the molecular clusters on the porous anodized aluminum surface. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 205–210, March–April, 2007.     

An efficient inversion algorithm for atmospheric remote sensing with application to UV limb observations

In this paper we present a retrieval algorithm for atmospheric remote sensing. The algorithm combines Tikhonov regularization and the iteratively regularized Gauss-Newton method and is devoted to the solution of multi-parameter inverse problems with simple bounds on the variables. The basic features of the algorithm: the solution of the bound-constrained minimization problem, the selection of the optimal regularization parameter, the derivation of the global regularization matrix and the characterization of the solution (error analysis) are discussed in detailed. The inversion algorithm is applied to ozone retrieval from SCIAMACHY limb scatter measurements in the ultraviolet spectral range.     

统一混沌系统的时延模糊控制

在将统一混沌系统表达为T-S模型的基础上, 利用泛函微分方程的Lyapunov-Krasovskii稳定性理论和线性矩阵不等式(LMIs)方法,设计出一个新的带时延状态反馈模糊控制器.仿真结果显示,所设计的控制器能有效地控制统一混沌系统的混沌时间轨迹到其平衡点,且控制简单可靠.     

Time‐Dependent Afterglow Color in a Single‐Component Organic Molecular Crystal

An organic crystal of 4,4′‐bis(N‐carbazolyl)‐1,1′‐biphenyl (pCBP) exhibits time‐dependent afterglow color from blue to orange over 1 s. Both experimental and computational data confirm that the color evolution results from well‐separated, long‐persistent thermally activated delayed fluorescence (TADF) and room‐temperature phosphorescence (RTP) with different but comparable decay rates. TADF is enabled by a small S₁–T₁ energy gap of 0.7 kcal mol^?1. The good separation of TADF and RTP is due to a 11.8 kcal mol^?1 difference in the S₀ energies of the S₁ and T₁ structures, indicating that apart from the excited‐state properties, tuning the ground state is also important for luminescence properties. This afterglow color evolution of pCBP allows its applications in anticounterfeiting and data encryption with high security levels.