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71.
In this paper, we try to present the problem of epoch detection from a different perspective that not only deals with estimation
of epoch instances (i.e., glottal activity) but also with quantification of the absence of epochs (i.e., no glottal activity) in the unvoiced regions of speech signal. Most of the epoch detection methods perform significantly well
in the voiced regions of speech but are not robust enough in the unvoiced regions of speech, i.e., they detect a number of
pseudo epochs in the unvoiced regions of speech. We propose a simple method based on Teager Energy Operator (TEO) which not only
determines the epochs in voiced region (due to its superior temporal resolution and its ability to capture airflow properties
through the glottis) but also is very effective in unvoiced region. Recently proposed methods such as 0-Hz resonator-based
method and DYPSA method gave a combined rate (CR) (for detecting epochs in voiced and unvoiced regions of speech) of 74.7%
and 60%, respectively and a pseudo epoch rate (PER) (i.e., spurious epochs in the unvoiced regions of speech) of 62.9% and
54.04%, respectively. On the other hand, our proposed method gave a CR and PER of 87% and 0.27%, respectively. This result
suggests that the proposed method captures glottal activity more efficiently both in voiced and unvoiced regions of speech signal. The performance of the proposed method is demonstrated
using publicly available CMU-Arctic database using the epoch information from the electro-glottograph (EGG) as reference signal
to serve as ground truth for estimation of glottal closure instants (GCI). Due to the noise suppression capability of TEO,
the proposed method has almost no or little effect (i.e., robust) against signal degradations like white, babble, high frequency
and vehicle noises as compared to 0-Hz resonator and DYPSA methods. 相似文献
72.
Hilmi Syawal Nur Khuzaimah Farhana Zhi Ling Goh Shahid Bashir Norshahirah Mohamad Saidi Elizer Rachagan Subramaniam Ramesh Ramesh Kasi 《应用聚合物科学杂志》2021,138(44):51312
In this work, novel redox electrolytes based on poly (ethylene oxide) (PEO) were prepared using binary ionic liquid 1-methyl-3-propylimidazolium iodide (MPII) with 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMTFSI) or 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) to reduce the high viscosity of MPII. The addition of low viscosity ionic liquids is to overcome the low mass transportation of redox mediator faced by the single ionic liquid. Therefore, different ratios of ionic liquids were added, and their effect on the electrical properties of the ionic liquid-based gel polymer electrolytes (GPE) was observed. It was confirmed that all the system dominant by ions rather than electron. The binary ionic liquid system containing 37.5 wt.% of BMIMBF4 showed the highest ionic conductivity of 24.2 mS cm−1. Fourier-transform infrared and X-ray diffraction studies confirmed that complexation occurred between all materials. The combination of two alkyl side chain length has enhanced the efficiency of the DSSC with short-circuit current density (JSC) of 26.81 mA cm−1, open-circuit voltage (VOC) of 0.67 V, fill factor of 44.5% and photovoltaic conversion efficiency (η) of 7.8%. This work has provided valuable insight for further stability of binary ionic liquid-based GPE compared to single ionic liquid electrolytes. 相似文献
73.
Coronavirus disease 2019 (COVID-19) is an ongoing pandemic caused due to new coronavirus infection with 3716075 deaths across the world as reported by the World Health Organization (WHO). SARS-CoV-2 main protease (Mpro) plays a vital role in the replication of coronavirus and thus an attractive target for the screening of inhibitors for the therapy of COVID-19. The preclinical drugs ebselen and PX-12 are potent inhibitors of SARS-CoV-2 Mpro and covalently modifies the active site Cys-145 residue of Mpro through selenosulfide/disulfide. In the current report, using virtual screening methods, reactive sulfur species allicin is subjecting for covalent docking at the active site of SARS-CoV-2 Mpro using PX-12 as a benchmark reference compound. The results indicate that allicin induces dual S-thioallylation of Cys-145 and Cys-85/ Cys-156 residues of SARS-CoV-2 Mpro. Using density functional theory (DFT), Gibbs free energy change (DG) is calculated for the putative reactions between N-acetylcysteine amide thiol and allicin/allyl sulfenic acid. The overall reaction is exergonic and allyl disulfide of Cys-145 residue of Mpro is involved in a sulfur mediated hydrogen bond. The results indicate that allicin causes dual S-thioallylation of SARS-CoV-2 Mpro which may be of interest for treatment and attenuation of ongoing coronavirus infection. 相似文献
74.
S. Farooq Y. Munikrishna Reddy R. Padmasuvarna Venkata Krishnaiah Kummara C.S. Dwaraka Viswanath Sk. Mahamuda 《Ceramics International》2018,44(17):21303-21308
Dysprosium (Dy3+)-doped antimony-magnesium-strontium-oxyfluoroborate (B2O3 MgF2 SrO Sb2O3 Dy2O3, BMFSrSbD), glasses were synthesized by traditional melt-quenching method. The synthesized samples have been analyzed by X-ray diffraction, optical absorption and fluorescence techniques for deriving various characteristic properties. Emission spectra of Dy3+: samples were exhibit three well resolved emission bands at around 482, 575 and 666?nm which originated from the 4F9/2→6H15/2,4F9/2→6H13/2 and 4F9/2→6H11/2 transitions upon excitation of wavelength at 452?nm. Decay curves of the 4F9/2 level of Dy3+ ion were display mono-exponential at low Dy3+ concentration (0.1?mol%) and deviated to non-exponential behavior at high concentration of Dy3+ ions (≥?0.5?mol%). Lifetime of the 4F9/2 level was decreased with increase of Dy3+ ions concentration. Chromaticity coordinates (x,y) of Dy3+:BMFSrSbD samples were evaluated and represented in CIE 1931 chromaticity diagram, appear in the whitish-yellow region. The results suggest that these glasses could be utilized as a potential candidate for the development of display devices and lasers at a wavelength of 575?nm. 相似文献
75.
This paper presents experimental data on heat capacities and thermal conductivities of two ceramic tapes measured using standard ASTM methods. The two ceramic tapes were prepared using alumina and a glass ceramic of aluminum-magnesium silicate with poly(vinyl butyral) binder, and laminated at pressures of 208E5 to 620E5 Pa at two laminating temperatures and times. The measured properties showed that laminating pressures have a greater effect, and that thermal conductivities are affected more than heat capacities. Empirical models have been developed to fit the experimental data. A correlation is developed to express the density of laminated green sheets in terms of the laminating variables—time, temperature, and pressure. 相似文献
76.
Cadmium sulphide nanoparticles (6–12 nm) are prepared by a precipitation process using different zeolite matrices as templates. The nanoparticles were characterized by UV-Vis, XRD, SEM, TEM and sorptometric techniques. XRD study shows the presence of hexagonal and cubic phases for the nanoparticles whereas in case of the bulk samples only the hexagonal phase is observed. These nanomaterials have been used as catalysts for the photocatalytic decomposition of water. The nanoparticles show a higher hydrogen evolution rate compared to the bulk samples which correlates well with the particle size and surface area. Noble metal (Pt, Pd, Rh, Ru)-loaded samples were subsequently prepared and tested for hydrogen evolution reaction. The presence of Pt metal is found to enhance the hydrogen production rate whereas the hydrogen production rate is retarded in the presence of Ru metal. This has been explained on the basis of metal hydrogen bond, redox potential and work function of the noble metal. 相似文献
77.
The length change in response to changes in the surface stress during scans of the electrode potential was measured for nanoporous platinum samples immersed in aqueous NaF, an electrolyte with weak ion adsorption. The surface stress-charge response may be characterized separately for four different processes, selected by the potential range and by the surface pretreatment: hydrogen adsorption/desorption, oxygen adsorption/desorption (and/or surface oxidation/reduction), and nominally capacitive charging of the Pt surface in two different states, clean and oxide-covered. While each process exhibits a roughly linear response, the magnitude and even the sign of the slope, which determines the surface stress-charge coefficient, ζ, differ. We suggest that the sign of ζ depends on the penetration depth of the excess charge: for strong screening the electronic charge is located outside of the surface, and ζ is negative as found previously for clean metal surfaces. For weaker screening, the wider space charge layer implies a trend for the excess charge to fill bulk-like unoccupied states. These states are here antibonding, giving positive-valued ζ. 相似文献
78.
A Monte Carlo simulation technique evaluates the reliability indices of restructured power systems with a hybrid market. A model for optimal transaction curtailment for a contingency state in a hybrid market is developed to incorporate the changes brought about by deregulation. The objective of the contingency optimal transaction curtailment for each individual generation company is to minimise its revenue loss. The problem is formulated as a linear programming problem and solved using an optimisation technique. Customer load curtailment, which is the basic parameter for reliability evaluation, is determined using a load-shedding philosophy which is based on the results of the optimal transaction curtailment by the genco. Supply and demand transactions of the market participants are represented by a transaction matrix. The impact of the firm and nonfirm bilateral and reserve contracts on customer reliabilities have been studied. The technique has been illustrated by application to the IEEE Reliability Test System. 相似文献
79.
Jagannatha Gopalakrishnan Ram P. Viswanath Kuttanikkat V. Govindan Kutty 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1978,28(11):751-755
Hydrogen reduction of V2O5 and WO3 catalysed by rhodium, both in the pure form and supported on kieselguhr, has been studied. The products obtained at 300°C have been identified as VO2 and HxWO3. In situ electrical resistivity measurements on V2O5 pellets, both pure and admixed with the catalyst, show an anomalous resistance increase with temperature, perhaps arising from chemisorption and spillover of hydrogen from rhodium. 相似文献
80.
Widera J Bunker CE Pacey GE Katta VR Brown MS Elster JL Jones ME Gord JR Buckner SW 《Applied optics》2005,44(6):1011-1017
A new method of analysis employing the time-dependent response of long-period-grating (LPG) fiber-optic sensors is introduced. The current kinetic approach allows analysis of the time-dependent wavelength shift of the sensor, in contrast to previous studies, in which the LPG sensing element has been operated in an equilibrium mode and modeled with Langmuir adsorption behavior. A detailed kinetic model presented is based on diffusion of the analyte through the outer protective membrane coating into the affinity coating, which is bound to the fiber cladding. A simpler phenomenological approach presented is based on measurement of the slope of the time-dependent response of the LPG sensor. We demonstrate the principles of the kinetic methods by employing a commercial Cu+2 sensor with a carboxymethylcellulose sensing element. The detailed mathematical model fits the time-dependent behavior well and provides a means of calibrating the concentration-dependent time response. In the current approach, copper concentrations below parts per 10(6) are reliably analyzed. The kinetic model allows early-time measurement for low concentrations of the analyte, where equilibration times are long. This kinetic model should be generally applicable to other affinity-coated LPG fiber-optic sensors. 相似文献