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111.
Vocal perturbation, harmonics-to-noise, and intensity measures were obtained for 10 subjects during three experimental tasks: (a) prolonged /a/, (b) /pa/ with vowel prolonged, and (c) same as (b) with subjects wearing a pneumotachographic mask and oral pressure tube inserted between the lips. There were no statistically significant differences among the experimental conditions for any of the measures. The findings suggest that a single task may be used to obtain airflow, oral pressure, and acoustic measures of vocal performance. Observed differences in jitter and harmonic-to-noise means for the male and female speakers are discussed. 相似文献
112.
Properties of β-connected spaces 总被引:1,自引:0,他引:1
Many characterizations of semipreconnected (=β-connected) spaces are obtained by Aho and Nieminen [2]. In this paper, we obtain
further characterizations of semipreconnected spaces. We introduce β-separated and βs-connected sets and by using these sets we obtain several properties of β-connected subspaces.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
113.
Mandana Samari Kermani Ned Djilali Saeed Jafari Ebrahim Jahanshahi Javaran 《Journal of Dispersion Science and Technology》2018,39(6):777-791
The dynamics and rheology of particles in a Newtonian fluid subjected to shear are simulated using Lattice Boltzmann Method. A computationally-efficient Smoothed Profile Method is used to resolve fluid-solid interactions, and the Lennard-Jones inter-particle potential is implemented to account for inter-particle forces. The use of a bi-periodic computational domain with Lees-Edward boundary conditions allows simulation for systems consisting of a large number of particles under shear. The method is validated for single and dual particle problems and an analysis is performed for multi-particle problems under a range of shear rates and particle fractions. The introduction of particle-particle interactions, which are physically important in many engineering processes, is found to have a considerable impact on the dynamics, agglomeration and rheology. The total stress exhibits high unsteadiness primarily due to the solid component contribution, at higher particle fractions. The simulations underscore the complex interplay between shear, interparticle forces and agglomeration and the complex dependencies of the rheological properties. 相似文献
114.
Ali Nakhaei Pour Yahya Zamani Kheirolah Jafari Jozani Jafar Yeganeh Mehr 《Reaction Kinetics and Catalysis Letters》2005,86(1):157-162
Summary The effect of La2O3 and TiO2 on product selectivity, methane conversion and coke formation over NiO/MgO/ α -Al2O3 catalyst were studied in a simultaneous steam and CO2 reforming of methane to syngas. La2O3 and TiO2 were added to the catalyst via incipient wetness impregnation and bulk precipitation techniques and catalyst activity was tested in a fixed bed quartz reactor. Results reveal that although the addition of these oxides has no effect on the product selectivity and methane conversion, but can reduce coke formation on the surface of the catalysts as it can enhance the mobility of lattice oxygen anions. The results further show that the catalysts prepared by bulk precipitation technique decrease the coke formation more effectively. 相似文献
115.
A fast and accurate analytical method, which uses commercially available adsorbents (Tenax TA, Carbotrap B and C, and Carbosieve S-III), was developed for the sampling and determination of aromatic hydrocarbons, chloroaromatic compounds, and 2,3,7,8-tetrachlorodibenzo-p-dioxin. The breakthrough volume data show that Carbotrap C has a good capacity for compounds of high molecular weight, whereas Carbosieve S-III and Tenax TA are efficient for volatile compounds. The organic components are thermally desorbed and transferred to a gas chromatograph/mass spectrometer. Importantly, thermal desorption avoids conventional solvent extraction procedures and also allows reuse of adsorbent tubes. Preliminary results for recovery of analytes from tubes packed with single adsorbent prove that a single-adsorbent bed is not capable of sampling a wide range of compounds. The best method to obtain the desired collection and desorption properties is to use adsorbent tubes containing several different materials. The results of optimization studies are summarized. 相似文献
116.
117.
118.
Hojat Allah Badehian 《Molecular Crystals and Liquid Crystals》2017,650(1):138-146
We present an accurate theoretical technique to investigate electronic, electrical, mechanical and optical characteristic of metal@semiconductor ((4,0)@(8,0)) and metal@metal ((6,0)@(12,0)) double-walled carbon nanotubes. The simulation was conducted in the framework of a combination of DFT and Non-Equilibrium Green's Function (NEGF). The outputs reinforced that by decreasing interwall distance the π-conjugate delocalized electrons movement and the transmission characteristics of these sort of nanotubes are affected. Moreover, the obtained results showed the stability of double-walled CNTs with small interlayer distance due to the compatibility of the rotational symmetry of inner and outer tubes. Nevertheless, the electrical conductivity of (4,0)@(8,0)DWCNTs is extraordinary less than (6,0)@(12,0) DWCNTs and those of their internal and external SWCNTs separately. However, Young's modulus of DWCNTs (4,0)@(8,0) remained in Tetra Pascal range. 相似文献
119.
Ligand‐free Mizoroki–heck reaction using reusable modified graphene oxide‐supported Pd(0) nanoparticles
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Palladium nanoparticles supported on graphene oxide surfaces modified with metformin was found to be an effective and recyclable nanocatalyst in Mizoroki–Heck coupling reactions under aerobic conditions without requiring any phosphine or ligand coordination. Excellent product yields were achieved with a wide variety of substrates and the catalyst could be recycled seven times without any noticeable loss of its catalytic activity. 相似文献
120.
Suzuki–Miyaura coupling catalyzed by palladium nanoparticles biosynthesized using Glycyrrhiza glabra as reducing and stabilyzing agent
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Hojat Veisi Mehdi Adib Rahman Karimi‐Nami Zahra Yasaei Mahnaz Tajik Talieh Sadat Mosavat Saba Hemmati 《应用有机金属化学》2018,32(3)
An unprecedented environmentally friendly method has been developed for the synthesis of palladium nanoparticles supported on Glycyrrhiza glabra. The synthesized nanoparticles were utilized in Suzuki–Miyaura reaction between different aryl halides and aryl bronic acid in aqueous media. This heterogeneous catalyst can be reused and recycled repeatedly more than five times with only slight loss of its initial catalytic efficiency. This reaction carrid out under atmospheric pressure with high efficiency, unique and simple work‐up procedure and excellent yields. 相似文献