Multivariate Hazard Rates under Random Censorship

The data consists of multivariate failure times under right random censorship. By the kernel smoothing technique, convolutions of cumulative multivariate hazard functions suggest estimators of the so-called multivariate hazard functions. We establish strong i.i.d. representations and uniform bounds of the remainder terms on some compact sets of the underlying space. Thus asymptotic normality and uniform consistency on such sets are obtained. The asymptotic mean squared error gives an optimal bandwidth by the plug-in method. Simulations assess the performance of our estimators.     

Asymptotic behavior of the unbounded solutions of some boundary layer equations

We give an asymptotic equivalent at infinity of the unbounded solutions of some boundary layer equations arising in fluid mechanics.Received: 24 May 2004     

A semi-lagrangian numerical method for geometric optics type problems

Linear multistep methods (LMMs) are written as irreducible general linear methods (GLMs). A-stable LMMs are shown to be algebraically stable GLMs for strictly positive definite G-matrices. Optimal order error bounds, independent of stiffness, are derived for A-stable methods, without considering one-leg methods (OLMs). As a GLM, the OLM is shown to be the transpose of the LMM. For A-stable methods, the LMM G-matrix is the inverse of the OLM G-matrix. Examples of G-symplectic LMMs are given. AMS subject classification (2000) 65L20     

Effect of sensitizer adsorption temperature on the performance of dye-sensitized solar cells

Employing a mesoscopic titania photoanode whose bilayer structure was judiciously selected to fit the optoelectronic characteristics of the Ru-based heteroleptic complex Na-cis-Ru(4,4'-(5-hexyltiophen-2-yl)-2,2'-bipyridine)(4-carboxylic-acid-4'-carboxylate-2,2'-bipyridine)(thiocyanate)(2), coded as C101, we investigated the effect of temperature for dye adsorption on the photovoltaic performance of dye-sensitized solar cells (DSCs). We found a significant efficiency enhancement upon lowering the temperature applied during the sensitizer uptake from solution. When the dye adsorption was performed at 4 °C, the photovoltaic performance parameters measured under standard reporting conditions (AM1.5 G sunlight at 1000 W/m(2) intensity and 25 °C), i.e., the open circuit voltage (V(oc)), the short circuit photocurrent density (J(sc)), the fill factor (FF), and consequently the power conversion efficiency (PCE), improved in comparison to cells stained at 20 and 60 °C. Results from electrochemical impedance spectroscopy (EIS) and attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) show that the self-assembled layer of C101 formed at lower temperature impairs the back-electron transfer from the TiO(2) conduction band to the triiodide ions in the electrolyte more strongly than the film produced at 60 °C. Profiting from the favorable influence that the low-temperature dye uptake exerts on photovoltaic performance, we have realized DSCs showing a power conversion efficiency of 11.5%.     

Filtering and Control with Information Increasing

In this paper, we consider a filtering problem where the observation filtration is enlarged with a future information. In the linear case, we obtain the filter equations and study the associated linear regulator problem.     

Mixed L 2-Wasserstein Optimal Mapping Between Prescribed Density Functions

A time-dependent minimization problem for the computation of a mixed L ²-Wasserstein distance between two prescribed density functions is introduced in the spirit of Ref. 1 for the classical Wasserstein distance. The optimum of the cost function corresponds to an optimal mapping between prescribed initial and final densities. We enforce the final density conditions through a penalization term added to our cost function. A conjugate gradient method is used to solve this relaxed problem. We obtain an algorithm which computes an interpolated L ²-Wasserstein distance between two densities and the corresponding optimal mapping.     

Complexes cationiques η-1′,2,3-[(methylene-2γ-butyrolactone)-yl-3]-(η-cyclopentadienyl)carbonylnitrosyl molybdene: Synthese et etudes des additions nucleophiles stereoselectives

The decomposition of hydroxyethyl-, ethoxyethyl- and phenoxyethyl(aquo)cobaloximes in sulfuric acid/water mixtures to produce ethylene has been studied spectrophotometrically and manometrically. Definitive kinetic evidence for formation of an intermediate which is common to all three starting complexes and accumulates at acidities greater than 7.3 M H₂SO₄ has been obtained. A complete rate law which accounts for all of the ionizations of starting materials and intermediate has been derived and fit to the rate data. The rate-determining step for product formation is decomposition of the intermediate at all acidities: the intermediate accumulates in strong acid because of a shift in the equilibrium for its formation due to the reduced activity of water in strongly acidic media. Activation parameters for the decomposition of the intermediate, which may be formulated as an ethylene-cobaloxime(III) π-complex or as a σ-bonded ethyl carbonium ion, have been obtained. ¹H and ¹³C NMR observations of the intermediate and its deuterated analog (from 1,1,2,2-tetradeuterio-2-hydroxyethyl(aquo)cobaloxime) have led to the conclusion that it is probably a σ-bonded ethyl carbonium ion which may be stabilized by σ-π hyperconjugation.     

Domain Decomposition,Optimal Control of Systems Governed by Partial Differential Equations,and Synthesis of Feedback Laws

We present an iterative domain decomposition method for the optimal control of systems governed by linear partial differential equations. The equations can be of elliptic, parabolic, or hyperbolic type. The space region supporting the partial differential equations is decomposed and the original global optimal control problem is reduced to a sequence of similar local optimal control problems set on the subdomains. The local problems communicate through transmission conditions, which take the form of carefully chosen boundary conditions on the interfaces between the subdomains. This domain decomposition method can be combined with any suitable numerical procedure to solve the local optimal control problems. We remark that it offers a good potential for using feedback laws (synthesis) in the case of time-dependent partial differential equations. A test problem for the wave equation is solved using this combination of synthesis and domain decomposition methods. Numerical results are presented and discussed. Details on discretization and implementation can be found in Ref. 1.     

Direct computation of multivalued phase space solutions for Hamilton‐Jacobi equations

A method is presented for the complete resolution of Hamiltonian systems using only the corresponding Hamilton‐Jacobi equation. © 1999 John Wiley & Sons, Inc.