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71.
Smid Jiri Hsiau Shu-San Chyou Yau-Pin Huang Ta-Ching Liu Ti-Chen 《Advanced Powder Technology》2012,23(5):548-557
An experimental two-dimensional (2-D) thin slice panel for studying flow patterns of fine silica sand was designed and manufactured. As supplier of sand was not known at that time, flow properties of the silica sand were assessed without shear tests. A preliminary design of plane-flow hopper of the experimental 2-D panel was assumed to be close to the mass flow conditions. Sand was circulated in the experimental panel to study the steady state flow. Tests of flow patterns suggested typical funnel-flow patterns with stagnant zones in the hopper and in the vertical part of the panel. Stagnant zones near the bottom of the hopper indicated insufficient width of the hopper outlet. Shear tests for estimation of flow properties of silica sand were carried out additionally and two methods of how to transform the funnel flow of sand to the mass flow were followed up; (a) existing 2-D panel was retrofitted with flow-corrective element, and (b) the width of outlet in existing experimental panel was widen into the size, calculated according to mass flow conditions. Both modifications were proven to be successful and the last-in first-out funnel flow was transformed into first-in first-out mass flow of sand. Velocities of individual tracer particles were measured during mass flow and velocity field was evaluated. Velocity profile of particles in the vicinity of flow-corrective insert was studied in detail. 相似文献
72.
Simulation and numerical modeling are becoming increasingly popular due to the ability to seek solutions for a problem without undertaking real-life experiments. For the problems of heat transfer, these techniques to generate relevant data by incorporating different changes to the input parameters. Heat transfer property of textile materials is a major concern since it influences comfort properties of clothing. In this paper, numerical simulation was applied to evaluate the heat flux, temperature distributions, and convective heat transfer coefficients of the fibrous insulating materials treated with aerogel. The computational model simulated the insulation behavior of nonwoven fabrics without and with aerogel. Ansys and Comsol were used to model and simulate heat transfer. The simulation was performed assuming laminar flow and since the Mach number was < 0.3, the compressible flow model with Mach number < 0.3 was used. The results of simulation were correlated to experimental measurements for validation. Furthermore, aerogel-treated fabric samples showed better thermal performance. Using this model, the heat transfer properties of the nonwoven fabrics treated with aerogel can be optimized further. 相似文献
73.
This editorial provides an overview of a special issue dedicated to the 7th conference on Process Integration, Modeling and Optimization for Energy Saving and Pollution Reduction—PRES 2004. Eight papers have been selected and peer-reviewed covering various subjects of heat transfer engineering, focusing on the recent development of various features of heat transfer equipment design and optimization. This is the fourth special issue of Heat Transfer Engineering dedicated to selected contributions from PRES conferences [1, 2, 3]. 相似文献
74.
The chemical and rheological properties of two asphalts selected from different sources (Urals, Russia; Cold Lake, Canada) were investigated. Analyses of chemical (elemental composition, fractional composition, molecular weights) and physical properties (complex viscosity, loss tangent, shear compliance) were performed on all original and aged (rolling thin film oven test, RTFOT; pressurized aging vessel, PAV) samples. The analyses of the chemical properties of both asphalts revealed higher asphaltene content, higher heteroatom content, and lower aging susceptibility of the Cold Lake asphalt (less significant changes in group composition). Based on its chemical composition, the Cold Lake asphalt was expected to perform better in the rheological tests than the Urals asphalt. The rheological tests confirmed this hypothesis and revealed better low- and high-temperature properties of the Cold Lake asphalt and a slower deterioration of its physical properties upon oxidative aging. 相似文献
75.
The microstructure and fracture properties of the Eurofer97 steel plates of thickness 14 mm and 25 mm were investigated in as-received state and in state after long-term thermal ageing (550 °C/5000 h). Detailed microstructure studies were carried out by means of optical light, electron and quantitative electron microscopy. Mechanical properties were evaluated by means of Charpy impact testing and hardness testing and fracture surfaces were fractographically analysed in macro and microscales. The microstructure of the Eurofer97 consisted of tempered martensite with M23C6 and MX precipitates. Microstructure of 14 mm plate was more homogenous and fine grained than 25 mm plate. Due to different microstructure the tDBTT of thicker plate was on +10 °C higher than for 14 mm plate for which reached −60 °C. Slight microstructural changes on the level of subgrain consisting of their partial recrystallization and slight carbide coarsening were observed after applied ageing. The isothermal ageing caused evident shift in tDBTT about +5 °C, which was most likely caused by recrystallization of subgrains. 相似文献
76.
Operators of bulk material silos frequently face various flow defects. These include defects in flow continuity, vaults, stick rings, and dead zones in the bulk material. The application of aeration systems in bulk material silos is an effective method used in order to eliminate the above defects. This paper presents a study of the effect of an aeration system on wall pressures σW of bulk material in a silo during a targeted bulk material aeration and relaxation process, and analyses the results in light of the calculation standards for designing bulk material silos, namely ?SN 73 5570 a DIN 1055. 相似文献
77.
Invasive fungus-growing ambrosia beetles are an emerging threat to forest ecosystems and fruit industries, but management
tools are lacking. Here we explored the potential of beetle symbionts–ambrosia fungi–as a source of attractants. Our focus
was the redbay ambrosia beetle, Xyleborus glabratus, and its symbiotic fungus, Raffaelea lauricola, which are devastating lauraceous hosts in the southeastern United States. We also tested three additional co-occurring beetle
species and their symbionts. Each beetle species was consistently attracted to the odors of its symbiotic fungal species,
occasionally also to symbionts of other species, but never to non-symbiotic Trichoderma. We further confirmed attraction to ethanol (positive control) in some species. Thus, ambrosia fungi produce volatiles attractive
to their vector beetles, which may have potential as novel lures for ambrosia beetle management. 相似文献
78.
79.
Bark cloth fabric has been in production in Uganda since the thirteenth century. In a move to preserve its cultural heritage, the United Nations Educational, Scientific and Cultural Organization (UNESCO) proclaimed in 2005 that Ugandan bark cloth is a “Masterpiece of the Oral and Intangible Heritage of Humanity.” Plant fibers require surface treatment before aimed at impurity reduction and for enhancement of fiber to matrix adhesion in composites. An exploratory investigation of enzymatic and plasma treatment of bark cloth is reported. The morphology of the fabric was investigated using scanning electron microscope. Thermal behavior of the fabric was studied using thermogravimetric analysis and differential scanning calorimetry. Fourier transform infrared spectroscopy and ultraviolet–visible (UV–vis) spectrophotometer were used to evaluate the surface functional groups. Enzyme-treated fabrics were cleaner and thermally stable compared to plasma and untreated fabrics. 相似文献
80.
Rajesh Mishra Richa Tiwari Miroslava Marsalkova B.K. Behera Jiri Militky 《纺织学会志》2013,104(12):1361-1368
In the present investigation, a novel technique has been developed to fabricate composite materials containing TiO2 nanoparticles, polysiloxane resin, and basalt fabric. A high-intensity ultrasonic probe was used to obtain a homogenous molecular mixture of TiO2 nanoparticles and polysiloxane resin, thus the nanoparticles were infused into the resin through sonic cavitation. The loading effect of TiO2 nanoparticles on the thermal and mechanical properties of basalt fabric reinforced polysiloxane composite materials has been investigated. Composite samples were prepared, each using two layers of basalt fabric with TiO2 nanoparticles loading from 0.5, 1, 1.5, 2, 2.5, and 3% by weight. Size distribution of nanoparticles was observed by particle size analyzer and the prepared fabric nanocomposites were characterized by scanning electron microscopy, dynamic mechanical analysis (DMA), thermo gravimetric analysis (TGA), and differential scanning calorimetry (DSC). Tensile testing was performed as per American standard for testing of materials (ASTM) standards. The dependence of dynamic mechanical parameters E′, E′′, tan (delta), T g, and heat distortion temperature (HDT) are associated with the filler content and can be controlled by the curing conditions. Tensile results show that 1.5 wt.% loading of TiO2 nanoparticles in the nanocomposites resulted in highest improvement in tensile modulus compared to the neat system. DMA studies also revealed that 1.5 wt.% doped system exhibits highest storage modulus as compared to the neat and other loading percentages. DSC and TGA studies show that T g and HDT of the composite increases with the increase in wt.% of nanofillers in the composite. Based on these results, it is clear that miscibility of nanoparticles in the resin is of prime importance with regard to performance. 相似文献