Comparison of spectral variation from spectroscopy to spectral imaging

Optical biopsy has been shown to discriminate between normal and diseased tissue with high sensitivity and specificity. Fiber-optic probe-based spectroscopy systems do not provide the necessary spatial information to guide therapy effectively, ultimately requiring a transition from probe-based spectroscopy to spectral imaging. The effect of such a transition on fluorescence and diffuse reflectance line shape is investigated. Inherent differences in spectral line shape between spectroscopy and imaging are characterized and many of these differences may be attributed to a shift in illumination-collection geometry between the two systems. Sensitivity of the line-shape disparity is characterized with respect to changes in sample absorption and scattering as well as to changes in various parameters of the fiber-optic probe design (e.g., fiber diameter, beam steering). Differences in spectral line shape are described in terms of the relative relationship between the light diffusion within the tissue and the distribution of source-detector separation distances for the probe-based and imaging illumination-collection geometries. Monte Carlo simulation is used to determine fiber configurations that minimize the line-shape disparity between the two systems. In conclusion, we predict that fiber-optic probe designs that mimic a spectral imaging geometry and spectral imaging systems designed to emulate a probe-based geometry will be difficult to implement, pointing toward a posteriori correction for illumination-collection geometry to reconcile imaging and probe-based spectral line shapes or independent evaluation of tissue discrimination accuracy for probe-based and spectral imaging systems.     

Removal of fluoride from aqueous solution by polypyrrole/Fe3O4 magnetic nanocomposite

Highly efficient visible light TiO₂ photocatalyst was prepared by the sol-gel method at lower temperature (≤300 °C), and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and differential scanning calorimetry-thermogravimetric analysis (DSC-TGA). The effects of the heat treatment temperature and time of the as-prepared TiO₂ on its visible light photocatalytic activity were investigated by monitoring the degradation of methyl orange solution under visible light irradiation (wavelength ≥ 400 nm). Results show that the as-prepared TiO₂ nanoparticles possess an anatase phase and mesoporous structure with carbon self-doping and visible photosensitive organic groups. The visible light photocatalytic activity of the as-prepared TiO₂ is greatly higher than those of the commercial TiO₂ (P-25) and other visible photocatalysts reported in literature (such as PPy/TiO₂, P3HT/TiO₂, PANI/TiO₂, N-TiO₂ and Fe³⁺-TiO₂) and its photocatalytic stability is excellent. The reasons for improving the visible light photocatalytic activity of the as-prepared TiO₂ can be explained by carbon self-doping and a large amount of visible photosensitive groups existing in the as-prepared TiO₂. The apparent optical thickness (τ_app), local volumetric rate of photo absorption (LVRPA) and kinetic constant (k_T) of the photodegradation system were calculated.     

纺织品的容许色差

色彩推动了纺织品市场的发展。对于生产者和厂家来说色差问题一直是一个颇具争议的现象，色差数据并不是总能够符合人们对颜色深浅的视觉估计。这里给出了一些不同颜色深浅的容许量数据(△E)，叙述了如何正确地选择计算色彩差异的公式以及这些公式的局限性，同时也讨论了关于颜色的视觉估计以及电脑测色系统之间的关系，介绍了用分光光度分析不同表面特征的织物的方法．     

A Highly Accurate Dysphonia Detection System Using Linear Discriminant Analysis

The recognition of pathological voice is considered a difficult task for speech analysis. Moreover, otolaryngologists needed to rely on oral communication with patients to discover traces of voice pathologies like dysphonia that are caused by voice alteration of vocal folds and their accuracy is between 60%–70%. To enhance detection accuracy and reduce processing speed of dysphonia detection, a novel approach is proposed in this paper. We have leveraged Linear Discriminant Analysis (LDA) to train multiple Machine Learning (ML) models for dysphonia detection. Several ML models are utilized like Support Vector Machine (SVM), Logistic Regression, and K-nearest neighbor (K-NN) to predict the voice pathologies based on features like Mel-Frequency Cepstral Coefficients (MFCC), Fundamental Frequency (F₀), Shimmer (%), Jitter (%), and Harmonic to Noise Ratio (HNR). The experiments were performed using Saarbrucken Voice Database (SVD) and a privately collected dataset. The K-fold cross-validation approach was incorporated to increase the robustness and stability of the ML models. According to the experimental results, our proposed approach has a 70% increase in processing speed over Principal Component Analysis (PCA) and performs remarkably well with a recognition accuracy of 95.24% on the SVD dataset surpassing the previous best accuracy of 82.37%. In the case of the private dataset, our proposed method achieved an accuracy rate of 93.37%. It can be an effective non-invasive method to detect dysphonia.     

Lattice Boltzmann simulation of lid-driven swirling flow in confined cylindrical cavity

Lid-driven swirling flow in a confined cylindrical cavity is investigated using lattice Boltzmann equation (LBE) method. The steady, 3-dimensional flow is examined at different aspect (height-to-radius) ratios and Reynolds numbers. The LBE simulations are carried out using the multiple-relaxation-time method. The LBE simulation results are compared with the results of a finite volume solution of Navier-Stokes equations and with published experimental data. Numerical results are presented for cylindrical cavities with two aspect ratios of 1.5 and 2.5, and three Reynolds numbers of 990, 1010 and 1290. Effects of the aspect ratio and Reynolds number on the size, position and breakdown of the central recirculation bubble, together with the flow pattern in the cavity, are determined. Detailed topological features of the flow, such as, (1) structure and breakdown of the vortex along the axis, (2) azimuthal component of vorticity, and (3) circulation strength of flow about the axis are investigated and compared with previous findings from experiments and theory.The predicted results from LBE simulations are consistent with experiments and theory. Steady results reveal the occurrence of a breakdown bubble in agreement with the regime diagram due to Escudier. The vortex breakdown around a region may be characterized by a change in sign of the azimuthal vorticity near such locations. Investigations are carried out on the characteristics of angular momentum when the vortex breakdown occurs. The theoretical criterion for vortex breakdown to occur, as proposed by Brown and Lopez is verified using the numerical data obtained from the simulations.     

Droplet transport through dielectrophoretic actuation using line electrode

We explore a novel transverse line electrode configuration for droplet transport through dielectrophoretic actuation with potential lab-on-chip applications. Using a lumped electromechanical model, we show a weak dependence of DEP actuation force on electrode spacing in this configuration. The configuration successfully triggers translational drop motion with minimal changes in contact angle at considerably low voltages. Two sessile, deionized water drops placed horizontally apart on a indium-tin–oxide-coated glass with additional coatings of polydimethylsiloxane, and a thin layer of Teflon is merged by applying an AC field (88 V_rms at 150 kHz) through a common horizontal wire electrode. A lateral motion of two drops is induced along the horizontal electrode, eventually leading to coalescence. The drop motion is unique compared to electrowetting in its near-constant dynamic contact angle, and irreversibility on withdrawal of electric field. The effect of frequency on the drop behavior is examined through a parametric study on single drops within the range of 2–200 kHz. It is interesting to observe a switch-over from DEP behavior at high frequency to EWOD behavior at low frequency around a critical frequency (Jones in Langmuir 18:4437–4443, 2002).     

Constitution and properties of ceramized fireclay refractories: I. Constitution

A poor-grade fireclay was mixed with three nucleating agents, namely Cr₂O₃, V₂O₅ and TiO₂. The fireclay and oxide mixed fireclay were fired at 1300°C for 1 h, cooled down to room temperature and then heat-treated at 1150°C for 15h. These were also heat-treated at 1150°C for 15 h after cooling down to 1150°C from the peak temperature. The heat-treatment caused ceramization of the glassy phase in the fireclay samples, and the samples, mineralogical composition and microstructure were investigated. Ceramization brought about significant changes in the microstructure only.     

Constitution and properties of ceramized fireclay refractories: II. Properties

Low-grade fireclay refractories contain large amounts of glassy phase. The properties, e.g. mechanical strength, thermal-shock resistance, refractoriness-under-load, refractoriness and also porosity and bulk density of these refractories before and after ceramization of their glassy phase were investigated. The glassy phase was ceramized by incorporating Cr₂O₃, V₂O₅ and TiO₂ into the refractories as nucleating agents and subsequent heat-treatment. Significant improvement in mechanical strength and thermal-shock resistance of the ceramized refractories was observed.