Tracer Diffusion and Electrical Conductivity in Sodium-Rubidium Silicon Sulfide Glasses

The tracer diffusion coefficients of ²²Na and ⁸⁶Rb and electrical conductivity were measured in a series of 0.56(Na, Rb)₂S.0.44SiS₂ glasses as a function of the Rb/Na ratio and temperature. The data were used to calculate the Haven ratio as a function of the Rb/Na ratio. The Haven ratio at 149.6°C increases from ∼0.3 in single-alkali glasses to ∼0.80 for intermediate compositions. The results are consistent with a single jump mechanism involving jumps of alkali ions between unoccupied sites. The observed correlation effects arise through interactions between alkali ions and charge-compensating centers in the glass network. The charge-compensating centers are thought to correspond to non-bridging oxygen ions in some oxide glasses and to nonbridging sulfur ions in sodium-rubidium silicon sulfide glasses.     

ROTOR RESISTANCE ESTIMATION FOR SLIP ADAPTATION IN SENSORLESS INDUCTION MACHINE DRIVES

ABSTRACT

This work presents a rotor resistance estimation algorithm. The estimation process is based on a recursive least squares method. It is applied to a speed sensorless induction motor drive scheme in order to implement slip adaptation. A discrete approach is considered in which an induction motor model written in form of difference equations is used by the estimation algorithm. All the associated mathematical developments are shown. Simulation results are used to verify the performance of the proposed rotor resistance estimator.     

Effects of Dithiocarbamate Fungicides on Corrosion Mechanisms and Shelf-Life Behavior of Light Acid Fruits in Plain Tin Containers

From the results of monitoring commercial test packs, synthetic test packs, and related laboratory experiments, the effects of dithiocarbamate fungicide residues on the shelf-life of canned acid fruits in plain tin containers have been clearly demonstrated. It has been shown that the sulfur compounds resulting from the decomposition of the fungicides are the “active” species and, depending on the quantity of fungicide initially present, can control corrosive failure through pitting corrosion mechanisms. Steel chemistry has also been shown to be an important factor in these interactions as evidenced by the superior performance of aluminum deoxidized continuous cast containers when compared to containers produced from type L ingot steel.     

瑞典多功能绿道的实际建设 挑战与机遇

探讨了瑞典南部的斯堪尼亚在建设多功能绿道时,在改善高强度管理农业区域可达性、休闲活动可能性和生物多样性等方面所面临的挑战和机遇。通过网络检索、与政府部门进行联系,与相关人员进行讨论及召开研讨会,并对绿道的生物多样性进行实地调查,指出了瑞典绿道的实际问题与改善的可能性。     

An evaluation of imaging spectrometry for estimating forest canopy chemistry

Abstract

High spectral resolution Airborne Imaging Spectrometer (AIS) data were acquired over 20 well-studied Wisconsin forest sites to evaluate the potential of remote sensing for estimating forest canopy chemistry. Intensive nutrient cycling research in these forests demonstrates that canopy lignin content is strongly related to measured annual nitrogen mineralization at the undisturbed sites and may serve as an accurate index for nitrogen cycling rates. Ground measurements were made of foliar biomass and canopy nitrogen and lignin content, the latter within two weeks of the AIS overflight. The spectral data were transformed using derivative techniques modified from laboratory spectroscopy. Stepwise regression assisted in determining combinations of wavelengths most highly correlated with canopy chemistry and biomass. Strong correlations between AIS data and total canopy lignin content in deciduous forests and canopy lignin concentration (total lignin/biomass) in both deciduous and coniferous stands indicate that imaging spectrometry can be used to estimate canopy lignin content and, from that, the spatial distribution of annual nitrogen mineralization rates.     

93Nb Fourier Transform NMR Spectroscopy of Lithium Niobate Ceramic Samples

Lithium niobate is a very important material for integrated optical devices. The results of a Fourier transform NMR study of nonstoichiometric ceramic samples of this material are reported here. A random distribution in nuclear quadrupole coupling constant, with an approximately Lorentzian probability density function, accounts for changes observed in the NMR spectra.