Comparing two video-based techniques for driver fatigue detection: classification versus optical flow approach

Lack of concentration in a driver due to fatigue is a major cause of road accidents. This paper investigates approaches that can be used to develop a video-based system to automatically detect driver fatigue and warn the driver, in order to prevent accidents. Ocular cues such as percentage eye closure (PERCLOS) are considered strong fatigue indicators; thus, accurately locating and tracking the driver’s eyes is vital. Tests were carried out based on two approaches to track the eyes and estimate PERCLOS: (1) classification approach and (2) optical flow approach. In the first approach, the eyes are tracked by finding local regions, the state (open or closed) of the eyes in each image frame is estimated using a classifier, and thereby the PERCLOS is calculated. In the second approach, the movement of the upper eyelid is tracked using a newly proposed simple eye model, which captures image velocities based on optical flow, thereby the eye closures and openings are detected, and then the eye states are estimated to calculate PERCLOS. Experiments show that both approaches can detect fatigue with reasonable accuracy, and that the classification approach is more accurate. However, the classification approach requires a large amount of suitable training data. If such data are unavailable, then the optical flow approach would be more practical.     

Polyaniline membranes for nanofiltration of solvent from dewaxed lube oil

Polyaniline nanofiltration membranes were synthesized to examine a potential candidate for application of solvent recovery from lube oil. An integrally skinned polyaniline membrane was cast on a woven polyester fabric and then was chemically crosslinked with glutaraldehyde in order to further increase the membranes resistant in a methyl ethyl ketone and toluene mixture. Subsequently, membrane performance was tested under different operational conditions. The operation pressure was fixed at 35 bar and was held constant for all of the tests. The membrane demonstrated a permeate flux of 10 l/(m² h) and oil rejection of 69%.

Abbreviations: PANi: Polyaniline; PI: polyimide; MEK: methyl ethyl ketone; GA: glutaraldehyde; NMP: N-methyl-2-pyrrolidone; 4MP: 4-methylpiperidine; SEM: Scanning Electron Microscope; OSN: organic solvent nanofiltration; MWCO: molecular weight cut-off.     

Effect of cobalt bis(dicarbollides) on electrochemical oxygen reduction on Pt electrode in methanol-acid solution

Electrochemical oxygen reduction on a platinum electrode has been investigated in methanol-0.05 M H₂SO₄ aqueous solutions in the presence of acids of cobalt bis(dicarbollide) (H⁺B⁻, H⁺[(1,2-C₂B₉H₁₁)₂-3-Co]⁽⁻⁾) or its hexachlorinated derivative (H⁺BCl⁻, H⁺ [(8,8′,9,9′,12,12′-Cl₆-(1,2-C₂B₉H₈)₂-3-Co)]⁽⁻⁾). Methanol oxidation was suppressed with H⁺BCl⁻ significantly, and selective oxygen reduction was achieved on a platinum electrode. The efficiency of oxygen reduction to H₂O, which depended on the electrode potential, was lower by 2% to 20% than that without H⁺BCl⁻. The mechanism was investigated by surface-enhanced infrared absorption spectroscopy (SEIRAS). H⁺BCl⁻ suppresses formation of both the catalytic poison, linear CO (ads.), from methanol and the formate, the intermediate of the non-CO path of methanol oxidation.     

Sonochemical synthesis and characterization of zinc tungstate nanoparticles and investigation of its photocatalyst application

Zinc tungstate nanoparticles were synthesized via a sonochemical method based on the reaction between zinc (II) nitrate hexahydrate and sodium tungstate dihydrate in water. The structural, morphological and optical properties of as-obtained products were characterized by techniques such as X-ray diffraction, scanning electron microscopy, energy dispersive X-ray microanalysis, and ultraviolet–visible spectroscopy. The samples indicated a ferromagnetic behavior, as evidenced by using vibrating sample magnetometer at room temperature. To evaluate the catalytic properties of nanocrystalline zinc tungstate, the photocatalytic degradation of methyl orange under ultraviolet light irradiation was carried out.     

HgCdTe mid-wavelength IR photovoltaic detectors fabricated using plasma induced junction technology

Preliminary characterization results are presented for mid-wave infrared (MWIR) mercury cadmium telluride n-on-p photodiodes fabricated using a plasma induced type conversion junction formation technology. The diodes have been fabricated on three different vacancy doped p-type epitaxial starting materials, grown by liquid phase epitaxy (LPE) on CdZnTe, LPE on sapphire, and P/p isotype heterojunction material grown by molecular beam epitaxy (MBE) on CdZnTe. All materials had CdTe mole fraction in the active region of the device of ∼0.3. The process uses a H₂/CH₄ plasma generated in a parallel plate reactive ion etching (RIE) system to type convert the p-type material to n-type. The process is different from previously reported type conversion techniques in that it does not require a high temperature anneal, does not expose the junction at the surface to atmosphere after formation, and requires significantly fewer process steps than other planar processes. Homojunction devices fabricated using this process exhibit R₀A values >10⁷ Ω·cm² at 80 K. The R₀A is diffusion limited for temperatures >∼135 K. Results for responsivity, bias dependence of dynamic resistance — junction area product and 1/f noise show that the resulting diodes are comparable to the best planar diodes reported in the literature.     

An isogeometric solid‐like shell element for nonlinear analysis

An isogeometric solid‐like shell formulation is proposed in which B‐spline basis functions are used to construct the mid‐surface of the shell. In combination with a linear Lagrange shape function in the thickness direction, this yields a complete three‐dimensional representation of the shell. The proposed shell element is implemented in a standard finite element code using Bézier extraction. The formulation is verified using different benchmark tests. Copyright © 2013 John Wiley & Sons, Ltd.     

Sigma–delta architectures for pulse-stuffing synchronizers

The technique of pulse stuffing is widely used in synchronous digital communication networks. The similarity of pulse-stuffing synchronizers and sigma–delta modulators is identified in this paper. In particular it is shown that the popular stuff threshold modulation and adaptive threshold modulation schemes used in digital communications are essentially the same as the dithering and multiloop architectures of sigma–delta (ΣΔ) modulators. Using the similarity between pulse-stuffing synchronizers and ΣΔ modulators, two alternative circuits that are suitable for jitter reduction in pulse-stuffing synchronizers are proposed in the paper. For this purpose the look-ahead decision feedback (LADF) and multistage (MASH) architectures of ΣΔ modulators are modified such that they are suitable for use as pulse-stuffing synchronizers. It is shown that the performance of the proposed alternative synchronizer circuits surpasses the performances of the jitter reduction techniques currently used in the synchronizers, such as adaptive threshold modulation and stuff threshold modulation. © 1997 by John Wiley & Sons, Ltd.     

Antiviral Activity of Baicalein and Quercetin against the Japanese Encephalitis Virus

Japanese encephalitis (JE), a mosquito-borne viral disease, is endemic to the entire east and southeast Asia, and some other parts of the world. Currently, there is no effective therapeutic available for JE; therefore, finding the effective antiviral agent against JEV replication is crucial. In the present study, the in vitro antiviral activity of baicalein and quercetin, two purportedly antiviral bioflavonoids, was evaluated against Japanese encephalitis virus (JEV) replication in Vero cells. Anti-JEV activities of these compounds were examined on different stages of JEV replication cycle. The effects of the compounds on virus replication were determined by foci forming unit reduction assay (FFURA) and quantitative RT-PCR. Baicalein showed potent antiviral activity with IC₅₀ = 14.28 μg/mL when it was introduced to the Vero cells after adsorption of JEV. Quercetin exhibited weak anti-JEV effects with IC₅₀ = 212.1 μg/mL when the JEV infected cells were treated with the compound after virus adsorption. However, baicalein exhibited significant effect against JEV adsorption with IC₅₀ = 7.27 μg/mL while quercetin did not show any anti-adsorption activity. Baicalein also exhibited direct extracellular virucidal activity on JEV with IC₅₀ = 3.44 μg/mL. However, results of quantitative RT-PCR experiments confirmed the findings from FFURA. This study demonstrated that baicalein should be considered as an appropriate candidate for further investigations, such as the study of molecular and cellular mechanism(s) of action and in vivo evaluation for the development of an effective antiviral compound against Japanese encephalitis virus.     

非饱和粉砂临界状态的试验研究

非饱和土临界状态给出了土变形过程的终点,对于分析土的基本力学性质和建立相应的本构模型十分重要。以非饱和粉砂为研究对象,利用非饱和土双压力室三轴试验系统(GDS)开展相关试验研究,对不同干密度粉砂在不同净应力和吸力条件下剪切至临界状态过程中,分别测定了强度、体变、含水率及饱和度等相关状态参量的变化规律。结果表明:剪切至临界状态过程中,不同干密度非饱和粉砂的强度和变形特性差异明显;随轴向应变的不断增加,不同初始干密度粉砂试样的偏应力、体应变以及饱和度曲线最终趋于稳定值,试样剪切达到临界状态。基于试验结果,揭示了临界状态条件下非饱和粉砂强度、孔隙比、孔隙水比体积随吸力的变化规律,并建立了q–p?、ν–ln p?、νw–ln p?平面内的临界状态线方程,提出了从强度、变形和孔隙水三个方面对非饱和粉砂临界状态进行综合描述的方法。