用非相干光时间延迟四波混频测量超快速过程

本文报道了在双极性扩散系数较大情况下,用非相干光时间延迟四波混频测量失相时间和光栅衰减时间的理论,并对计算结果进行了讨论。     

Optimal finite-dimensional solution for a class of nonlinear observation problems

The filtering problem in a differential system with linear dynamics and observations described by an implicit equation linear in the state is solved in finite-dimensional recursive form. The original problem is posed as a deterministic fixed-interval optimization problem (FIOP) on a finite time interval. No stochastic concepts are used. Via Pontryagin's principle, the FIOP is converted into a linear, two-point boundary-value problem. The boundary-value problem is separated by using a linear Riccati transformation into two initial-value problems which give the equations for the optimal filter and filter gain. The optimal filter is linear in the state, but nonlinear with respect to the observation. Stability of the filter is considered on the basis of a related properly linear system. Three filtering examples are given.     

Analysis of 18 months of data of the GEOGRAV experiment

Summary We report on the analysis of 18 months of data of the GEOGRAV experiment: a room temperature gravitational-wave antenna equipped with various sensors of geophysical quantities (accelerometer, gravimeter and electrical antenna). We present results on the search for sidereal periodicities in the background of the gravitational-wave antenna as regards both hourly averages and large-amplitude pulses.

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Riassunto Si riferisce sull'analisi di 18 mesi di dati dell'esperimento GEOGRAV: un'antenna gravitazionale a temperatura ambiente equipaggiata con sensori di grandezze geofisiche (accelerometro, gravimetro ed antenna elettrica). Si presentano risultati sulla ricerca di periodicità siderali nel fondo dell'antenna gravitazionale, per quanto riguarda sia le medie orarie che gli impulsi di grande ampiezza.

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Резюме Мы анализируем данные, полученные в течение 18 месяцев в эксперименте ?GEOGRAV?: антенна гравитационных волн при комнатной температуре, снабженная различными датчиками геофизическин величин (акселерометр, гравиметр и электрическая антенна). Приводятся результаты по поиску сидерических периодичностей в фоне антенны гравитационных волн.

     

Improvement of stability and luminescence properties in water of Eu(III) and Tb(III) complexes photosensitized by a bipyridine antenna

The convenient synthesis of a new macrocyclic octadentate chelate based on 2,2′-bipyridine chromophore and diethylenetriaminetriacetic acid core is described. In aqueous solutions, the corresponding Eu(III) and Tb(III) neutral complexes are kinetically inert and show very bright luminescence when excited with UV radiation (Φ=11 and 25% respectively). We also report the potentiality of these complexes to act as donors in delayed fluorescence resonance energy transfer (DEFRET).     

固体表面延迟荧光测定中草药中有效成分柚皮甙

以层析聚酰胺膜为基质，以ＬｉＡｃ作增强剂，建立了测定痕量中草药有效成分柚皮甙的固体表面延迟荧光法，该法聚样量少（２ｕＬ），线性范围宽（２．９～５８０．０ｎｇ／斑），检出限为０．０３３ｎｇ／斑。     

Femtosecond Time-Resolved Third-Order Nonlinear Response of 4-(N, N-Diethylamino)-β-Nitrostyrene Solutions in the Nonresonant Region—Experimental Evidence of Group-Velocity Dispersion Effec—

We measure the femtosecond time-dependent, third-order nonlinear optical response for 4-(N, N-diethylamino)-β-nitrostyrene (DEANST) dissolved in N, N-dimethylformamide (DMF) from 0.1 to 1.4 M concentrations in the nonresonant region using time-resolved degenerate four-wave mixing (DFWM) spectroscopy. It is found that the DFWM signal profile with delayed responses depends on the concentration. This concentration dependence is determined to be mainly due to the group-velocity dispersion effect of the DEANST solution at the high concentration and the nonlinear response of the DMF solvent at the low concentration, but not due to the change in third-order nonlinear response of DEANST itself.     

A proposal to implement a quantum delayed choice experiment assisted by cavity QED

We propose a scheme with current technology to implement a quantum delayed-choice experiment in the realm of cavity QED. Our scheme uses two-level atoms interacting on and off resonantly with a single mode of a high Q cavity. At the end of the protocol, the state of the cavity returns to its ground state, allowing new sequential operations. The particle and wave behavior, which are verified in a single experimental setup, are postselected after the atomic states are selectively detected.     

Stability and periodicity in discrete delay equations

In this research we study the stability of the zero solution of delay difference equations and the existence of unique periodic solution by utilizing fixed point theory. Mainly, we are interested in the qualitative analysis of the complete delay difference equation

Δx(t)=−a(t)x(t−τ).     

Numerical approximations for nonlinear stochastic systems with delays

We extend the numerical methods of [Kushner, H.J. and Dupuis, P., 1992 Kushner, H.J. and Dupuis, P. 2001. Numerical Methods for Stochastic Control Problems in Continuous Time, 2nd ed., Berlin and New York: Springer-Verlag. [Crossref] , [Google Scholar], Numerical Methods for Stochastic Control Problems in Continuous Time, 2nd ed., 2001 (Berlin and New York: Springer Verlag], known as the Markov chain approximation methods, to controlled general nonlinear delayed reflected diffusion models. Both the path and the control can be delayed. For the no-delay case, the method covers virtually all models of current interest. The method is robust, the approximations have physical interpretations as control problems closely related to the original one, and there are many effective methods for getting the approximations, and for solving the Bellman equation for low-dimensional problems. These advantages carry over to the delay problem. It is shown how to adapt the methods for getting the approximations, and the convergence proofs are outlined for the discounted cost function. Extensions to all of the cost functions of current interest as well as to models with Poisson jump terms are possible. The paper is particularly concerned with representations of the state and algorithms that minimize the memory requirements.