A DEM method for simulating rubber tyres

Recently, recycled rubber tyres were found to be an economical and environmental-friendly reinforcement material in geotechnical engineering. Although the use of rubber tyre-reinforced soil has become increasingly popular, there is still a lack of a robust and systematic method to model rubber tyres when using the discrete-element method (DEM) to investigate the stress-strain responses. In this paper, DEM rubber tyres are simulated by bonding regular-packed balls, and numerically tested under tensile force using the particle flow code in three dimensions. When comparing the effects of different packings on the sample, using Young's modulus and Poisson's ratio, it was found that only body-centred-cubic packing could achieve a Poisson's ratio of 0·5 representing no volume change during the deformation of rubber. The difference between uniaxial compression and tension simulations was also compared as well as the influences of particle overlapping, particle radius and sample aspect ratio on the mechanical response of the tyre model. Finally, the DEM parameters were set to match the experimental Young's modulus data. This proposed DEM rubber tyre strips model could be a basis to study other rubber reinforcements such as tyre chips and shreds, irregular rubber buffings and granulated rubber

Insecticidal activity of essential oil of Cinnamomum cassia and its main constituent, trans-Cinnamaldehyde, against the booklice, Liposcelis bostrychophila

Purpose: To investigate the insecticidal activity of the essential oil of Cinnamomum cassis and its main constituent compound, trans-cinnamaldehyde, against the booklice, Liposcelis bostrychophila．Methods: Steam distillation of C. cassis twigs was carried out using a Clavenger apparatus in order to obtain the volatile oils. Gas chromatography/mass spectrometric (GC/MS) analyses (HP-5MS column) of the essential oil were performed and its contact (using impregnated filter paper method) and fumigant toxicity (sealed space) determined. The bioactive constituent compound, trans-cinnamaldehyde was isolated and identified from the oil based on bioactivity-directed fractionation.Results: A total of 35 components, accounting for 97.44 % of the essential oil of C. cassis, were identified. The principal compounds in the essential oil were trans-cinnamaldehyde (49.33 %), acetophenone (6.94 %), trans-cinnamic acid (5.45 %) and cis-cinnamaldehyde (4.44 %) followed by omethoxycinnamaldehyde (3.48 %), coumarin (3.42 %) and (E)-cinnamyl alcohol (3.21 %). The essential oil displayed contact toxicity against adult L. bostrychophila with a median lethal concentration (LC50) of 55.68 μg/cm2 as well as fumigant toxicity (LC50, 1.33 mg/l air). Trans-cinnamaldehyde exhibited strong contact and fumigant toxicity with LC50 and 1.29 mg/l air, respectively.Conclusion: The findings suggest that the essential oil of C. cassis and its constituent compound, trans-cinnamaldehyde, possess potentials for development into natural fumigants/insecticides for the control of booklice.Keywords: Liposcelis bostrychophila, Cinnamomum cassis, Contact toxicity, Fumigant, trans- Cinnamaldehyde, Essential oi

多粒度的GIS數據不確定性粗集表達

Author name used in this publication: 邓敏Author name used in this publication: LI Zhi-linAuthor name used in this publication: 程涛2005-2006 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Double vagueness : uncertainty in multi-scale fuzzy assignment of duneness

Author name used in this publication: LI Zhilin2003-2004 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Synthesis of compact NaA zeolite membrane by microwave heating method

A continuous and dense NaA zeolite membrane was synthesized by microwave heating method while employing a multi-step seeding LTA zeolite with the average size of 120 tun. The gas H-2/N-2 mixture separating results indicated that the mixture selectivity increased with increasing of synthesis times. In addition, selectivity of the three-step synthesis was higher than the value(3.74) expected from Kundsen diffusion

Response of Laser-Induced Thermal Lens Effect at Solid Surface

Recently Kuo et al. [1,2] and Satio et al.[3] presented the surface-thermal lens (STL) technique, this novel photothermal deformation technique has attracted great attention because it is a highly sensitive, noncontact and nondestructive measurement[4–6]. In this technique, a modulated pump beam is focused on the sample surface to produce the surface deformation and a cw probe beam is incident at the deformation region. Differing from the conventional photothermal deformation techniques, the spot size of the probe beam at the sample surface is much larger than the pump beam one. Then the probe beam reflected from the surface produces a diffraction pattern at the detection plane. More recently, STL technique has been successfully applied to study the temperature dependence of the thermal conductivity of semiconductor materials[5], weak absorption of optical thin films[6] and characterization of the solid materials[7,8]. However, the mechanism of STL phenomena has not been completely understood. Most theoretical models took no account of the influence of the air-thermal lens (ATL), although some experiment showed that the air significantly affected the detected diffraction pattern[2]. In addition, it is necessary to characterize frequency responses of signals because the response is used to determine the thermal property of the solid materials[5]

Morphology control and optical properties of SiGe nanostructures grown on glass substrate

With the rapid progress of nanotechnology, nanostructures with different morphologies have been realized, which may be very promising to enhance the performance of semiconductor devices. In this study, SiGe nanostructures with several kinds of configurations have been synthesized through a chemical vapor deposition process. By controlling growth conditions, different SiGe nanostructures can be easily tuned. Structures and compositions of the nanostructures were determined by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The optical properties of various SiGe nanostructures revealed some dependence with their morphologies, which may be suitable for solar cell applications. The control of the SiGe morphology on nanoscale provides a convenient route to produce diverse SiGe nanostructures and creates new opportunities to realize the integration of future devices

Architectural Growth of Cu Nanoparticles Through Electrodeposition

Cu particles with different architectures such as pyramid, cube, and multipod have been successfully fabricated on the surface of Au films, which is the polycrystalline Au substrate with (111) domains, using the electrodeposition technique in the presence of the surface-capping reagents of dodecylbenzene sulfonic acid and poly(vinylpyrrolidone). Further, the growth evolution of pyramidal Cu nanoparticles was observed for the first time. We believe that our method might open new possibilities for fabricating nanomaterials of non-noble transition metals with various novel architectures, which can then potentially be utilized in applications such as biosensors, catalysis, photovoltaic cells, and electronic nanodevices