The effect of illumination on the current-voltage characteristics and conductivity of MnGaInS<Subscript>4</Subscript> single crystals

We have studied the effect of illumination on the current-voltage characteristics and the temperature dependence of conductivity of MnGaInS₄ single crystals. Under illumination, the current in a sample was 10⁴–10⁵ times the dark value. It is established that the light-induced current buildup is due to the carrier release from the traps filled under illumination. The energy positions of levels are determined.     

Characteristics of Gas Condensate

The characteristic features of Oso condensate and Delta condensate samples, including their gasoline potential, were determined using gas chromatographic integrator techniques. The analysis revealed that these condensate samples have recoverable gasoline of 41.65% wt and 49.82% wt., respectively. Both samples are from Cross-River and Delta regions of the Nigerian oil fields, respectively. Two other crude oil samples from the Delta region, Forcados and Bonny light, were also analyzed alongside the two-condensate samples for comparative study. These analytical results show that the two crude oil samples are less rich in light fractions than the condensate samples. The results of the analysis of the four oil samples lend support to the earlier report that Nigerian crude oils are mostly paraffinic in nature.     

Motion compensated film restoration

Motion picture films are susceptible to local degradations such as dust spots. Other deteriorations are global such as intensity and spatial jitter. It is obvious that motion needs to be compensated for before the detection/correction of such local and dynamic defects. Therefore, we propose a hierarchical motion estimation method ideally suited for high resolution film sequences. This recursive block-based motion estimator relies on an adaptive search strategy and Radon projections to improve processing speed. The localization of dust particles then becomes straightforward. Thus, it is achieved by simple inter-frame differences between the current image and motion compensated successive and preceding frames. However, the detection of spatial and intensity jitter requires a specific process taking advantage of the high temporal correlation in the image sequence. In this paper, we present our motion compensation-based algorithms for removing dust spots, spatial and intensity jitter in degraded motion pictures. Experimental results are presented showing the usefulness of our motion estimator for film restoration at reasonable computational costs. Received: 9 July 2000 / Accepted: 13 January 2002 Correspondence to:S. Boukir     

动则生静则亡

松下电器产业于2007年3月16日宣布,将优先与美国投资基金TPG讨论旗下子公司Victor的出售,并最终在新的财政年度到来之前与TPG达成了收购协议.出售战略成功后,松下电器在投资基金的支持下得到重生.     

Chalcogenide Glasses Based on Germanium Disulfide for Second Harmonic Generation

High second‐order susceptibilities are created by thermal poling in bulk germanium disulfide based chalcogenide glasses. Experimental conditions of the poling treatment (temperature, voltage, time) were optimized for each glass composition. The second‐order nonlinear signals were recorded by using the Maker fringes experiment and a second‐order coefficient χ⁽²⁾ up to 8 pm V^–1 was measured in the Ge₂₅Sb₁₀S₆₅ glass. This value is obtained using a simulation based on accurate knowledge of the thickness of the nonlinear layer. Two mechanisms are proposed to explain the creation of a nonlinear layer under the anode: the formation and the migration of charged defects towards the anode may mainly occur in Ge₂₀Ga₅Sb₁₀S₆₅ and Ge₂₅Ga₅S₇₀ glasses, whereas the migration of Na⁺ ions towards the cathode may be responsible for the accumulation of negative charges under the anode in Ge₃₃S₆₇ and Ge₂₅Sb₁₀S₆₅ glasses. Different electronic conductivity behaviors seem to be at the origin of the phenomenon. In parallel, the potential effect of the poling treatment on the structural and electronic properties is studied using Raman spectroscopy and secondary ion mass spectroscopy measurements.     

Electrooptics of nematic-cholesteric droplets in constant electric field

Electrooptics and dynamics of twisted nematic-cholesteric liquid crystal (LC) droplets occurring in an isotropic environment in a dc electric field have been studied. The twist of the LC director field significantly influences the character of rotation of the cholesteric droplets. The most probable mechanism accounting for the rotation of cholesteric droplets is related to the Carr-Helfrich electrohydrodynamic instability.     

Nodally exact Ritz discretizations of 1D diffusion–absorption and Helmholtz equations by variational FIC and modified equation methods

This article presents the first application of the Finite Calculus (FIC) in a Ritz-FEM variational framework. FIC provides a steplength parametrization of mesh dimensions, which is used to modify the shape functions. This approach is applied to the FEM discretization of the steady-state, one-dimensional, diffusion–absorption and Helmholtz equations. Parametrized linear shape functions are directly inserted into a FIC functional. The resulting Ritz-FIC equations are symmetric and carry a element-level free parameter coming from the function modification process. Both constant- and variable-coefficient cases are studied. It is shown that the parameter can be used to produce nodally exact solutions for the constant coefficient case. The optimal value is found by matching the finite-order modified differential equation (FOMoDE) of the Ritz-FIC equations with the original field equation. The inclusion of the Ritz-FIC models in the context of templates is examined. This inclusion shows that there is an infinite number of nodally exact models for the constant coefficient case. The ingredients of these methods (FIC, Ritz, MoDE and templates) can be extended to multiple dimensions     

Thermodesorption of samarium from oxidized tungsten surface

Thermodesorption of samarium (Sm) atoms and samarium oxide (SmO) molecules from samarium films deposited in vacuum onto tungsten substrates covered with thin (<1 nm thick) layers of tungsten oxides has been studied. It is established that samarium reduces tungsten from its oxides. The parameters of Sm and SmO desorption from an oxidized tungsten surface are determined.