Synthesis and Characterization of the Titanium Containing Mesoporous Molecular Sieve MCM-48

Ti-MCM-48 mesoporous materials have been synthesized by sequential addition of alkoxides. The atomic ratio of Si and Ti in the synthesis gel was 40 and 5, respectively. The materials were characterized by means of powder XRD, N₂ adsorption-desorption measurements. HREM, ²⁹Si MAS NMR, diffuse reflectance FT-IR spectroscopy, electrophoretic mobility measurements and electron probe microanalysis.     

Simultaneous differential thermal and volume analysis at high pressure

Abstract

A method for simultaneous measurement of heat and volume changes associated with phase transformations is presented. Examples for melting, polymorphism and structural relaxation illustrate the method.     

Meshing Requirements for Tidal Modeling in the Western North Atlantic

This paper presents an a posteriori approach to unstructured mesh generation via a localized truncation error analysis and applies it to the Western North Atlantic Tidal (WNAT) model domain. The WNAT model domain encompasses the Gulf of Mexico, the Caribbean Sea, and the North Atlantic Ocean east to the 60°W Meridian. Herein, we pay particular attention to the area surrounding the Bahamas.

A bathymetric data set with fine resolution is employed in seven separate linear, harmonic simulations of shallow water tidal flow for seven different tidal-forcing constituents. Each set of simulation results is used to perform a truncation error analysis of a linear, harmonic form of the depth-averaged momentum equations for each of the seven different tidal-forcing frequencies. Truncation error is then driven to a more uniform, domain-wide value by solving for local node spacing requirements. The process is built upon successful research aiming to produce unstructured grids for large-scale domains that can be used in the accurate and efficient modeling of shallow water flow. The methodology described herein can also be transferred to other modeling applications.     

High‐Pressure Synthesis,Crystal Structure,and Properties of GdS2 with Thermodynamic Investigations in the Phase Diagram Gd–S

Gadolinium disulfide was prepared by high‐pressure synthesis at 8 GPa and 1173 K. It crystallizes in the monoclinic space group P12₁/a1 (No. 14) with lattice parameters a = 7.879(1) Å; b = 3.936(1) Å, c = 7.926(1) Å and β = 90.08(1)°. The crystal structure is a twofold superstructure of the aristotype ZrSSi and consists of puckered cationic [GdS]⁺ double slabs that are sandwiched by planar sulfur sheets containing S₂^2– dumbbells. The thermal decomposition of GdS₂ proceeds via the sulfur‐deficient polysulfides GdS_1.9, GdS_1.85 and GdS_1.77 and eventually results in the sesquisulfide Gd₂S₃. GdS₂ is a paramagnetic semiconductor which orders antiferromagnetically at T_N = 7.7(1) K. A metamagnetic transition is observed in the magnetically ordered state.     

Partial identification of the potential from phase shifts

We consider the three-dimensional inverse scattering with fixed energy in the spherically symmetrical case. We give a characterization of the sequences of phase shifts for two potentials which can be different only in a ball of radius a. In other words we study how the large distance interaction influences the asymptotical behavior of the phase shifts. We also characterize the tail of the potential by the growth order of the scattering amplitude F(t) for large t.     

Film-thickness Error Analysis of Optical Disk Systems

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Finite element analysis of thermally coupled nonlinear Darcy flows

We consider a coupled system describing nonlinear Darcy flows with temperature dependent viscosity and with viscous heating. We first establish existence, uniqueness, and regularity of the weak solution of the system of equations. Next, we decouple the coupled system by a fixed point algorithm and propose its finite element approximation. Finally, we present convergence analysis with an error estimate between continuous solution and its iterative finite element approximation.© 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2010     

NONLINEAR WAVELET SMOOTHING OF ERROR DENSITY IN A SEMIPARAMETRIC REGRESSION MODEL

In this paper,a semlparametrie resresaion model in which errors are i. i. d random variables from an unknown density f( ) is considered. Based on Hall et al. (1995),a nonlinear wavelet estimation of f( ) without restrictions of continuity everywhere on f( ) is given,and the convergence rate of the estimators in L2 is obtained.