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We theoretically explore the dynamics of a ferrofluid with temperature and magnetic field-dependent viscosity, which is in a Rayleigh–Bénard situation and is subjected to rotation. The problem considers both sinusoidal and non-sinusoidal time-periodic variations of rotation to study the onset and post-onset regimes of Rayleigh–Bénard ferroconvection. We perform a weakly nonlinear stability analysis using a truncated Fourier series representation and arrive at the third-order Lorenz system for ferrofluid convection with variable viscosity. By using the linearized form of the Lorenz system for ferrofluid convection with variable viscosity, we arrive at the critical Rayleigh number to study the onset of rotating ferroconvection. The heat transport is quantified in terms of the time-averaged Nusselt number and the effects of various parameters on it are studied. The effect of modulated rotation is found to have a stabilizing effect on the onset of ferroconvection while that of variable viscosity has a destabilizing effect. The effects of magnetorheological and thermorheological effects are antagonistic in nature. It is found that the square waveform modulation facilitates maximum heat transport in the system due to advanced onset of ferroconvection. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate a novel salinity sensor based on Tamm-plasmon-polariton (TPP), comprising different shapes of Bragg reflector (ordinary, texturing, and sawtooth) and metallic layer. The finite element method is used to study the considered structure and sensing performance by using the COMSOL multiphysics simulation procedure. Here, we study the effect of surface morphology on the sensitivity; firstly, in the case of one-dimensional photonic crystal-centered defect, it harms the sensitivity; secondly, texturing and sawtooth in the case of Tamm resonance increases the sensitivity, as for texturing the surface, the sensitivity quality factor (Q) = 236 and figure of merit (FOM) = 170. For sawtooth surfaces, Q = 272.4, and FOM = 199. The consequences of structural parameters on the efficiency of sensing are studied, and new procedures are proposed to enhance TPP-based sensors. A simple and functional alternative to conventional salinity sensors may be the proposed solution. [ABSTRACT FROM AUTHOR]

Extensive research is carried out in the analysis of non stationary signals. Most of the real time signals are non-stationary in nature. In most cases, these non stationary signals are of types viz defect / non defect, normal / abnormal etc. Hence analysis refers to categorising the signals. Developing a signal processing algorithm for performing the above task is a major challenge. In Machine learning, features are extracted and classifiers are used for categorizing the signals. Feature extraction can be done in time domain, frequency domain and spectral domain. In this paper, feasibility of Singular Value Decomposition (SVD), Framelet Transforms, Discrete Wavelet Transform (DWT) and Discrete Cosine Transform (DCT) for feature extraction is studied. These features are aggregated using statistical parameters, namely mean, skewness and kurtosis. These aggregated features are then fed to Back Propagation Network (BPN). Performance of Back Propagation Network is measured in terms of sensitivity, specificity and accuracy. [ABSTRACT FROM AUTHOR]

A special structure with Al-composition graded barriers in the active region was designed to provide a sawtooth layer for the multiple quantum barriers, which were investigated numerically. The simulation demonstrates that the output power of optimized structure has reached to 50 mW and the efficiency droop also has significantly improved. By detailedly analyzing the results, the advantages of the ultraviolet light emitting diodes with sawtooth barriers are attributed to the design, which could enhance the ability of electrons reservoir, modulate carrier distribution and suppress electron spill out from the active region. As a result, it can enhance the rate of carrier radiation recombination and ameliorate internal quantum efficiency. [ABSTRACT FROM AUTHOR]

Compared with powder-based process of additive manufacturing, slurry-based process can fabricate the ceramic components with better green density by casting thinner layers to improve the step effect. The main objective of this study is to develop a reliable slurry-layer casting system for building ceramic green parts. A premetered slurry-feeding mechanism was built to steadily supply the slurry and prevented the ripples on the layer from pulsation. Based on the techniques of slot-die coating and tape casting, a novel coater including a coat hanger distribution chamber and a doctor blade was designed and built to observe the distribution of the specified slurry and verify the feasibility of the slurry-layer casting. The experiment results revealed the distribution chamber with a suitable coat hanger angle that can uniformly deliver the slurry to the lips of the coater. The premetered coating method can simplify the process variables involved in the casting process. The slurry feeder exerts a considerable force on the slurry to overcome the influence of the viscosity. Sawtooth effect in the slurry-layer casting was observed and eliminated through the process of slurry preloading. Furthermore, an online coater cleanup device, which possesses the features of simple structure and high efficiency of residual slurry removal, was proposed. For the slurry with different formation used in the additive manufacturing of ceramic products, this study can be a pattern to build a reliable slurry-layer casting system with the principle of simple design, low cost, and easy cleanup. [ABSTRACT FROM AUTHOR]

Purpose: The d-wave is typically elicited after the termination of an increment flash, but a decrement flash provides an alternative, and perhaps more appropriate, stimulus to elicit the d-wave. Here, we investigated the affects of stimulus polarity on the electroretinogram (ERG) response. Methods: ERG responses elicited to increment and decrement flashes of varying intensity and duration from different background levels were measured from human participants to assess the b-wave and d-wave responses as a function of adaptation level and flash polarity. Response amplitudes were measured using standard metrics for waveform analysis. Results: The amplitude of the b-wave is larger than the d-wave regardless of flash polarity when using different background levels which maximized the dynamic range of the two waveforms. However, when response amplitudes are measured from a common background, the d-wave elicited with decrement flash was larger than the b-wave elicited by an increment flash. This trend was evident across a range of background levels. The b-wave and d-wave become separate entities when flash duration reaches approximately 50 ms. Rapid-on and rapid-off sawtooth stimuli were also tested against increment and decrement step stimuli that were matched in mean luminance. These two stimulus types produced different amplitude b-wave and d-wave responses, suggesting asymmetric effects of the two stimulus types on the retinal response. Conclusions: We conclude that the response properties of the b-wave and d-wave are influenced by the duration, polarity and waveform of the stimulus, as well as the background from which the stimuli arise. [ABSTRACT FROM AUTHOR]

This study presents an investigation on both the processing and morphological aspects of cutting-based metal fibers. A self-designed multi-tooth cutter is used to efficiently make continuous long fibers under a low-speed dry-cutting condition. A finite element method-aided analysis is conducted to elucidate the mechanisms of this method. Based on both simulated and experimental results, it is found that fiber morphology shows different characteristics when different processing parameters are used. Moreover, the fiber structure and appearance also significantly depends on the mechanical properties of raw materials. It is shown that the Cu fiber belongs to flow chip due to highly plastic deformation, while the hardened Cu-Be, Cu-Be-Ni alloy and SUS316L fibers exhibit fractured features. The combined segmented vertical fins and sawtooth structures can be periodically formed on the Cu-Be fibers under an appropriate condition. Besides these findings, the effects of sintering condition on the fiber morphology are also reported in this work. [ABSTRACT FROM AUTHOR]

The structures of three operating regions in HT-6B Tokamak have been studied by soft X-ray tomographic system with high sensibility and high time-space resolution. One of the requisites for forming sawtooth discharge is the effective heating action in the central region. In the sawtooth region there are five evolutional phases and five types of magnetic surface structures correspondingly; that is, the concentric, the eccentric, the double-core, the “MHD-type” and the “ultra-MHD type” magnetic surface structures. In the MHD oscillation region, there is a stable “MHD-type” magnetic surface structure. It consists of a crescent “hot core” and a circular “cold bubble” and rotates in the diamagnetic direction of electrons. In the resonant region, the resonant helical field improves the heating status and suppresses the MHD disturbances; therefore the single “MHD-type” magnetic surface changes into a sawtooth type one. [ABSTRACT FROM AUTHOR]