Thermal analyses, spectral characterization and structural interpretation of Yb3+ doped TeO2-ZnO-ZnCl2 glasses

Bulk-lasses have been prepared in the TeO2-ZnO-ZnCl2 systems. Their characteristic temperatures were determined and analyzed. Raman and FT-IR spectra were used to analyze the effect of ZnCl2 on the structure and spectral properties of tellurite glasses and OH- groups in this glass system. The spectroscopic properties including absorption spectra, emission cross-sections and fluorescence lifetimes of Yb3+ in TeO2-ZnO-ZnCl2 were measured and calculated. It is demonstrated that the progressive replacement less than 20 mol% of TeO2 by ZnCl2 improves the thermal stability, removes the OH- groups, turns TeO4 bipyramidal arrangement into TeO3 (and/or TeO3+1) trigonal pyramids structures and results in the decrease of the symmetry of the structure, which increases the emission cross-sections and lifetimes. But when the content of ZnCl2 up to 30 mol%, the glass system becomes more hygroscopic and introduces more OH- groups, which decrease the emission cross-sections and shorten the lifetimes. The results show that the glass system with (TeO2)-Te-69-(ZnO)-Zn-10-20ZnCl(2)-1Yb(2)O(3) is a desirable component for active laser media for high power generation. (c) 2005 Elsevier B.V. All rights reserved.

Spectral properties and stability of Er3+-doped TeO2-WO3 glass

Er3+-doped TeO2-WO3 glass was fabricated and characterized by absorption spectrum, fluorescence spectrum, Raman spectrum and stability. The Judd-Ofelt parameter ohm(t)(t = 2, 4, 6) were calculated from the absorption spectrum by the Judd-Ofelt theory. The fluorescence spectrum indicates that the fluorescence width at half-maximum (FWHM) is 66nm. The stimulated emission cross-section of Er3+ in TeO2-WO3 glass at 1532 nm was calculated to be 0.80 x 10(-20) cm(2) by McCumber theory. The phonon energy of TeO2-WO3 glass is found to be 931 cm(-1). The difference between crystallization onset temperature and glass transition temperature Delta T is 112 degrees C. These results show that Er3+-doped TeO2-WO3 glass has higher stability and good spectral properties, which were useful for broadband amplifier. (c) 2005 Elsevier B.V. All rights reserved.

Circulação e fluxo de material particulado em suspensão no principal canal de acesso à baía de Sepetiba

Entre 06/08/11 e 25/02/12 foram obtidas séries temporais contínuas de intensidade e direção das correntes e intensidade do eco ao longo de toda a coluna dágua, e medições, de temperatura e pressão, próximas ao fundo, na região adjacente ao canal de acesso à baía de Sepetiba (230'16.5"S e 4359'29.4"W, profundidade local de aproximadamente 25 m) através da utilização de um perfilador acústico ADCP (Acoustic Doppler Current Profiler), modelo WorkHorse BroadBand Sentinel (600 kHz, Teledyne-RDI). A partir dos dados adquiridos, observou-se a existência de correntes intensas próximo ao fundo (até 1,02 m/s), principalmente durante os períodos de enchente sob condições de sizígia, que são fortemente influenciadas pela orientação do canal de navegação. A análise das séries temporais das componentes da velocidade mostraram, em conformidade ao relatado por alguns autores, que esta é uma baía cuja circulação é fortemente influenciada pela dinâmica da maré sendo M2, M4, M6 e M8 as principais componentes harmônicas que atuam no sistema. Além disso, observou-se significativa assimetria da maré, sendo os períodos de enchente consideravelmente mais curtos e associados às correntes mais intensas, o que permite concluir que no setor investigado da baía de Sepetiba há dominância de enchente. Outra característica interessante da área de estudo relaciona-se à observação de que ventos intensos de S-SO são responsáveis pelo empilhamento de água no interior da baía, sendo que altura do nível da superfície da água apresenta relação direta com as variações da pressão atmosférica local. Em diversos períodos, quando há atuação de ventos de E-NE é possível encontrar Água Central do Atlântico Sul (ACAS) no interior da baía de Sepetiba, desde a sua entrada principal até as adjacências da ilha Guaíba. Além disso, foram identificadas diversas oscilações de baixa frequência que puderam ser associadas à variação da pressão atmosférica. Oscilações de alta frequência foram associadas à dinâmica da maré, a co-oscilações da maré e ao vento. Em relação à concentração de Material Particulado em Suspensão (MPS), durante os períodos de sizígia foram registradas as maiores concentrações material particulado na coluna dágua. Durante os períodos de sizígia, o fluxo de MPS é mais pronunciado do que durante as quadraturas, sendo que, independente do período da maré, o fluxo cumulativo de material particulado em suspensão é dirigido para o interior da baía de Sepetiba. Considerando o alinhamento dos vetores de velocidade em conformidade a direção preferencial do canal de navegação, tem-se que o fluxo cumulativo de MPS varia entre dirigido para SE na região próxima ao fundo, a dirigido para NE próximo ao topo da coluna dágua, o que sugere a deflexão do movimento das correntes em consequência do atrito. Ao longo de um dia, o fluxo do material particulado é mais pronunciado durante as enchentes, quando há aumento das tensões cisalhantes que atuam sobre o leito da baía redisponibilizando para a coluna dágua o material que estava depositado no fundo.

Waveguide based compact silicon Schottky photodetector with enhanced responsivity in the telecom spectral band.

We experimentally demonstrate an on-chip compact and simple to fabricate silicon Schottky photodetector for telecom wavelengths operating on the basis of internal photoemission process. The device is realized using CMOS compatible approach of local-oxidation of silicon, which enables the realization of the photodetector and low-loss bus photonic waveguide at the same fabrication step. The photodetector demonstrates enhanced internal responsivity of 12.5mA/W for operation wavelength of 1.55µm corresponding to an internal quantum efficiency of 1%, about two orders of magnitude higher than our previously demonstrated results [22]. We attribute this improved detection efficiency to the presence of surface roughness at the boundary between the materials forming the Schottky contact. The combination of enhanced quantum efficiency together with a simple fabrication process provides a promising platform for the realization of all silicon photodetectors and their integration with other nanophotonic and nanoplasmonic structures towards the construction of monolithic silicon opto-electronic circuitry on-chip.

Randomized nonlinear component analysis

Copyright © (2014) by the International Machine Learning Society (IMLS) All rights reserved. Classical methods such as Principal Component Analysis (PCA) and Canonical Correlation Analysis (CCA) are ubiquitous in statistics. However, these techniques are only able to reveal linear re-lationships in data. Although nonlinear variants of PCA and CCA have been proposed, these are computationally prohibitive in the large scale. In a separate strand of recent research, randomized methods have been proposed to construct features that help reveal nonlinear patterns in data. For basic tasks such as regression or classification, random features exhibit little or no loss in performance, while achieving drastic savings in computational requirements. In this paper we leverage randomness to design scalable new variants of nonlinear PCA and CCA; our ideas extend to key multivariate analysis tools such as spectral clustering or LDA. We demonstrate our algorithms through experiments on real- world data, on which we compare against the state-of-the-art. A simple R implementation of the presented algorithms is provided.

Magnetic-field-induced nonthermal occupation of higher subbands in a three-barrier tunneling structure

When injected electrons in a quantum well first experience an intersubband relaxation process before their escaping by tunneling through a double-barrier structure behind, the magnetic suppression of intersubband LO or LA phonon scattering can give rise to a noticeable nonthermal occupation in higher-lying subbands. That is clearly verified by the relative intensity ratio of the interband photoluminescence spectra for E-2-HH1 and E-1-HH1 transitions. The observed phenomenon may provide an effective method for controlling intersubband scattering rate, a central issue in so-called quantum cascade lasers, and facilitating the population inversion between subbands in quantum wells.

Intrasubband and intersubband transitions in lightly and heavily doped GaAs/AlGa1-xAs multiple quantum wells

We use a polarizer to investigate quantum-well infrared absorption, and report experimental results as follows. The intrasubband transition was observed in GaAs/AlxGa1-xAs multiple quantum wells (MQWs) when the incident infrared radiation (IR) is polarized parallel to the MQW plane. According to the selection rule, an intrasubband transition is forbidden. Up to now, most studies have only observed the intersubband transition between two states with opposite parity. However, our experiment shows not only the intersubband transitions, but also the intrasubband transitions. In our study, we also found that for light doping in the well (4x10(18) cm(-3)), the intrasubband transition occurs only in the lowest subband, while for the heavy doping (8x10(18) cm(-3)), such a transition occurs not only in the lowest subband, but also in the first excited one, because of the electron subband filling. Further experimental results show a linear dependence of the intrasubband transition frequency on the root of the well doping density. These data are in good agreement with our numerical results. Thus we strongly suggest that such a transition can be attributed to plasma oscillation. Conversely, when the incident IR is polarized perpendicular to the MQW plane, intersubband-transition-induced signals appear, while the intrasubband-transition-induced spectra disappear for both light and heavy well dopings. A depolarization blueshift was also taken into account to evaluate the intersubband transition spectra at different well dopings. Furthermore, we performed a deep-level transient spectroscopy (DLTS) measurement to determine the subband energies at different well dopings. A good agreement between DLTS, infrared absorption, and numerical calculation was obtained. In our experiment, two important phenomena are noteworthy: (1) The polarized absorbance is one order of magnitude higher than the unpolarized spectra. This puzzling result is well explained in detail. (2) When the IR, polarized perpendicular to the well plane, normally irradiates the 45 degrees-beveled edge of the samples, we only observed intersubband transition spectra. However, the intrasubband transition signals caused by the in-plane electric-field component are significantly absent. The reason is that such in-plane electric-field components can cancel each other out everywhere during the light propagating in the samples. The spectral widths of bound-to-bound and bound-to-continuum transitions were also discussed, and quantitatively compared to the relaxation time tau, which is deduced from the electron mobility. The relaxation times deduced from spectral widths of bound-to-bound and bound-to-continuum transitions are also discussed, and quantitatively compared to the relaxation time deduced from electron mobility. [S0163-1829(98)01912-2].

Fast Discrimination of Commerical Corn Varieties Based on Near Infrared Spectra

The existing methods for the discrimination of varieties of commodity corn seed are unable to process batch data and speed up identification, and very time consuming and costly. The present paper developed a new approach to the fast discrimination of varieties of commodity corn by means of near infrared spectral data. Firstly, the experiment obtained spectral data of 37 varieties of commodity corn seed with the Fourier transform near infrared spectrometer in the wavenurnber range from 4 000 to 12 000 cm (1). Secondly, the original data were pretreated using statistics method of normalization in order to eliminate noise and improve the efficiency of models. Thirdly, a new way based on sample standard deviation was used to select the characteristic spectral regions, and it can search very different wavenumbers among all wavenumbers and reduce the amount of data in part. Fourthly, principal component analysis (PCA) was used to compress spectral data into several variables, and the cumulate reliabilities of the first ten components were more than 99.98%. Finally, according to the first ten components, recognition models were established based on BPR. For every 25 samples in each variety, 15 samples were randomly selected as the training set. The remaining 10 samples of the same variety were used as the first testing set, and all the 900 samples of the other varieties were used as the second testing set. Calculation results showed that the average correctness recognition rate of the 37 varieties of corn seed was 94.3%. Testing results indicate that the discrimination method had higher precision than the discrimination of various kinds of commodity corn seed. In short, it is feasible to discriminate various varieties of commodity corn seed based on near infrared spectroscopy and BPR.

Determination of ethenzamide and acetoaminophen in quaternary powdered samples by near infrared spectroscopy and searching combination moving window partial least squares algorithm: effects of spectral resolution and signal-to-noise ratio

The present study reports an application of the searching combination moving window partial least squares (SCMWPLS) algorithm to the determination of ethenzamide and acetoaminophen in quaternary powdered samples by near infrared (NIR) spectroscopy. Another purpose of the study was to examine the instrumentation effects of spectral resolution and signal-to-noise ratio of the Buchi NIRLab N-200 FT-NIR spectrometer equipped with an InGaAs detector. The informative spectral intervals of NIR spectra of a series of quaternary powdered mixture samples were first located for ethenzamide and acetoaminophen by use of moving window partial least squares regression (MWPLSR). Then, these located spectral intervals were further optimised by SCMWPLS for subsequent partial least squares (PLS) model development. The improved results are attributed to both the less complex PLS models and to higher accuracy of predicted concentrations of ethenzamide and acetoaminophen in the optimised informative spectral intervals that are featured by NIR bands. At the same time, SCMWPLS is also demonstrated as a viable route for wavelength selection.

APPLICATION OF FACTOR-ANALYSIS TO CORRECTION OF SPECTRAL OVERLAP INTERFERENCE IN INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION-SPECTROMETRY

Correction of spectral overlap interference in inductively coupled plasma atomic emission spectrometry by factor analysis is attempted. For the spectral overlap of two known lines, a data matrix can be composed from one or two pure spectra and a spectrum of the mixture. The data matrix is decomposed into a spectra matrix and a concentration matrix by target transformation factor analysis. The component concentration of interest in a binary mixture is obtained from the concentration matrix and interference from the other component is eliminated. This method is applied to correcting spectral interference of yttrium on the determination of copper and aluminium: satisfactory results are obtained. This method may also be applied to correcting spectral overlap interference for more than two lines. Like other methods of correcting spectral interferences, factor analysis can only be used for additive spectral overlap. Results obtained from measurements on copper/yttrium mixtures with different white noise added show that random errors in measurement data do not significantly affect the results of the correction method.

Ship-board measurements and estimations of air-sea fluxes in the western tropical Pacific during TOGA COARE

Direct air-sea flux measurements were made on RN Kexue #1 at 40 degrees S, 156 degrees E during the Tropical Ocean Global Atmosphere (TOGA) Coupled Ocean-Atmospheric Response Experiment (COARE) Intensive Observation Period (IOP). An array of six accelerometers was used to measure the motion of the anchored ship, and a sonic anemometer and Lyman-alpha hygrometer were used to measure the turbulent wind vector and specific humidity. The contamination of the turbulent wind components by ship motion was largely removed by an improvement of a procedure due to Shao based on the acceleration signals. The scheme of the wind correction for ship motion is briefly outlined. Results are presented from data for the best wind direction relative to the ship to minimize flow distortion effects. Both the time series and the power spectra of the sonic-measured wind components show swell-induced ship motion contamination, which is largely removed by the accelerometer correction scheme, There was less contamination in the longitudinal wind component than in the vertical and transverse components. The spectral characteristics of the surface-layer turbulence properties are compared with those from previous land and ocean results, Momentum and latent heat fluxes were calculated by eddy correlation and compared to those estimated by the inertial dissipation method and the TOGA COARE bulk formula. The estimations of wind stress determined by eddy correlation are smaller than those from the TOGA COARE bulk formula, especially for higher wind speeds, while those from the bulk formula and inertial dissipation technique are generally in agreement. The estimations of latent heal flux from the three different methods are in reasonable agreement. The effect of the correction for ship motion on latent heat fluxes is not as large as on momentum fluxes.

Physico-chemical properties and component interactions in high solids food systems

The present study aimed to investigate interactions of components in the high solids systems during storage. The systems included (i) lactose–maltodextrin (MD) with various dextrose equivalents at different mixing ratios, (ii) whey protein isolate (WPI)–oil [olive oil (OO) or sunflower oil (SO)] at 75:25 ratio, and (iii) WPI–oil– {glucose (G)–fructose (F) 1:1 syrup [70% (w/w) total solids]} at a component ratio of 45:15:40. Crystallization of lactose was delayed and increasingly inhibited with increasing MD contents and higher DE values (small molecular size or low molecular weight), although all systems showed similar glass transition temperatures at each aw. The water sorption isotherms of non-crystalline lactose and lactose–MD (0.11 to 0.76 aw) could be derived from the sum of sorbed water contents of individual amorphous components. The GAB equation was fitted to data of all non-crystalline systems. The protein–oil and protein–oil–sugar materials showed maximum protein oxidation and disulfide bonding at 2 weeks of storage at 20 and 40°C. The WPI–OO showed denaturation and preaggregation of proteins during storage at both temperatures. The presence of G–F in WPI–oil increased Tonset and Tpeak of protein aggregation, and oxidative damage of the protein during storage, especially in systems with a higher level of unsaturated fatty acids. Lipid oxidation and glycation products in the systems containing sugar promoted oxidation of proteins, increased changes in protein conformation and aggregation of proteins, and resulted in insolubility of solids or increased hydrophobicity concomitantly with hardening of structure, covalent crosslinking of proteins, and formation of stable polymerized solids, especially after storage at 40°C. We found protein hydration transitions preceding denaturation transitions in all high protein systems and also the glass transition of confined water in protein systems using dynamic mechanical analysis.

Cross-cultural variability of component processes in autobiographical remembering: Japan, Turkey, and the USA.

Although the underlying mechanics of autobiographical memory may be identical across cultures, the processing of information differs. Undergraduates from Japan, Turkey, and the USA rated 30 autobiographical memories on 15 phenomenological and cognitive properties. Mean values were similar across cultures, with means from the Japanese sample being lower on most measures but higher on belief in the accuracy of their memories. Correlations within individuals were also similar across cultures, with correlations from the Turkish sample being higher between measures of language and measures of recollection and belief. For all three cultures, in multiple regression analyses, measures of recollection were predicted by visual imagery, auditory imagery, and emotions, whereas measures of belief were predicted by knowledge of the setting. These results show subtle cultural differences in the experience of remembering.

Investigation of the permeation of model formulations and a commercial ibuprofen formulation in Carbosil® and human skin using ATR-FTIR and multivariate spectral analysis

The purpose of the present study was to use attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and target factor analysis (TFA) to investigate the permeation of model drugs and formulation components through Carbosil® membrane and human skin. Diffusion studies of saturated solutions in 50:50 water/ethanol of methyl paraben (MP), ibuprofen (IBU) and caffeine (CF) were performed on Carbosil® membrane. The spectroscopic data were analysed by target factor analysis, and evolution profiles of the signal for each component (i.e. the drug, water, ethanol and membrane) over time were obtained. Results showed that the data were successfully deconvoluted as correlations between factors from the data and reference spectra of the components, were above 0.8 in all cases. Good reproducibility over three runs for the evolution profiles was obtained. From the evolution profiles it was observed that water diffused better through the Carbosil® membrane than ethanol, confirming the hydrophilic properties of the Carbosil® membrane used. IBU diffused slower compared with MP and CF. The evolution profile of CF was very similar to that of water, probably because of the high solubility of CF in water, indicating that both compounds are diffusing concurrently. The second part of the work involved a study of the evolution profiles of the components of a commercial topical gel containing 5% (w/w) of ibuprofen as it permeated through human skin. Although the system was much more complex, data were still successfully deconvoluted and the different components of the formulation identified except for benzyl alcohol which might be attributed to the low concentrations of benzyl alcohol used in topical formulations. (C) 2009 Elsevier B.V. All rights reserved.

A study on the cost sharing model for supply lead time reduction with component commonality

This paper studies a two-level supply chain consisting of components supplier and product assembly manufacturer, while the manufacturer shares the investment on shortening supply lead time. The objective of this research is to investigate the benefits of cost sharing strategy and adopting component commonality. The result of numerical analysis demonstrates that using component commonality can help reduce the total cost, especially when the manufacture shares a higher fraction of the cost of investment in shortening supply lead time.