Papers by Keyword: Large Scale

Abstract: In this work, we present a numerical study of mixed convection flows around large-scale heat sinks. It is based on the Cascade Lattice Boltzmann Method (LBM) for values of the Rayleigh number, in transitional regime, in the range 5×10⁷≤Ra≤5×10⁸ and for a Reynolds value fixed at Re=1000. The study is carried out in a rectangular cavity of dimension H subjected to periodic thermal and dynamic boundary conditions on its vertical walls. Two heat sources of (L', l', H/2) with a hot temperature T_h, are placed on the bottom wall of the cavity to simulate heat sinks. Fresh air (for cooling these heat sinks) is injected at a temperature T_c< T_h from the bottom of the cavity through two openings of length L''. The hot air is extracted through an opening (2L'' long) managed on the upper horizontal wall. The preliminary results, presented in this paper, are in the form of streamlines, isotherms and thermal profiles in the range of the Rayleigh number considered. Heat transfer is studied in terms of the average Nusselt number calculated over the entire surface of the two heat sources.

Abstract: Biodiesel is a biodegradable fuel derived from renewable biomass, such as soybean and cottonseed oil, which may be obtained by different processes and requires a material to catalyze the obtaining reactions. The irons spinel comes overlapping as excellent materials to catalyze the biodiesel production reactions. Thus, the purpose of this work was the use of Ni_0.5Zn_0.5Fe₂O₄ nanoferrite as a catalyst in esterification reactions. The nanoferrite was synthesized by combustion in large scale, 200g/batch, where time and the temperature of the reactions were measured, and characterized by XRD and measuring its surface area. The biodiesel was obtained from methyl and ethyl esterification of acidified soybean oil and cottonseed, at a temperature of 160°C for 1 hour, molar ratio 1:15, 3% of catalyst and analyzed by chromatography. The nanoferrite has shown peaks of greater intensity corresponding to a majority crystal phase of the spinel and a surface area of ​​64.17m²/g. The conversion results for the soybean oil were 99.08% in methyl route and 98.38% in ethyl route. For cottonseed oil were 88.79% in methyl route and 78.65% in ethyl route.

Abstract: Gram scale multi-layer graphene grown on polycrystalline SiC microspheres were prepared by continuously preparation method in argon through chemical vapor deposition process using liquid polysilacarbosilane as raw material. The observation of products obtained at different temperature confirmed the growth is temperature dependent process. The method could be developed to synthesis hybrid nanostructures based on multi-layer graphene grown on polycrystalline SiC microspheres.

Abstract: In order to meet the measuring performance requirement of both high accuracy and large range when measuring the large-scale space angle formed by non-uniplanar lines quantitatively based on the engineering background of ammunition assembly angle test, we propose a measurement method that uses line structured laser as a common measurement reference and combined with vision inspection technique to achieve the measurement of large-scale space angle formed by non-uniplanar axes. Ammunition assembly angle have been measured accurately by using this method which provides a scientific approach for quality evaluation of that type of ammunition.

Abstract: The wind tunnel testing of large scale section model of the Forth Nanjing Yangzi River Bridge was conducted by the section model with a scale of 1:20. The details of the bridge girder could be simulated more precisely with a large scale. In the testing, a comparison was between the original girder cross section and the girder section without rails and tracks in the attack angle of +5°. On top of this, the main factor that causes the vortex-induced vibration of the girder was due to the installation of guide rail in the bottom of the girder. The control of vortex-induced vibration research was conducted concerning the installation of the guide rail.

Abstract: The study of the mechanical properties of pile-soil interface is an important aspect to research the vertical bearing behavior of piles. Currently special direct shear tests and special simple shear tests are usually used to study the mechanical properties of soil-structure interface. But those tests have shortcomings of difficulty in simulating the force properties of complex interface. In this paper, the mechanical properties of different interface between soil and concrete surface were studied through the large-scale direct shear tests.

Abstract: Terrain rendering has long been an active research topic in computer graphic and virtual reality. If large and detailed, digital terrains can be represented by a huge amount of data and therefore of graphical primitives to render in real-time. A dynamic, realistic and seamless rendering scheme for large scale terrain was proposed in this paper, based on successive LOD tiles and GPU acceleration. Multi-resolution girds and images were used for view-dependent data control and grid simplification, and multi-thread mechanism was employed for visibility clipping and data exchange between memory and disk, at the same time, a seamless combination algorithm between tiles of terrain and texture was proposed. Experimental results of real scenes with open data and comparisons with traditional method demonstrate the efficiency and practicality of our method.

Abstract: Fused Quartz crucible with large scale was formed by gelcasting processing in this paper. Effects of dispersant, pH values and particle grading on solids content of slurries were discussed to increase the volume density of the green compacts and decrease the shrinkage and deformation during sintering. Effects of acrylamide content and the ratio of acrylamide to coupling agent on bending strength of the green compacts were investigated. Effects of the amount of initiator and curing temperature on the gelcasting processing were studied as well. The green compacts with solids content of 80% was obtained when the addition ratio of dispersant to Quartz powders was 0.3wt %, the ratio of Quartz powders in D50 of 1.9μm and 7.6μm was adjusted to 3:7, the addition ratio of acrylamide to Quartz powders was 1.0wt % and the ratio of acrylamide to coupling agent was 16:1. The bending strength of the sinterred produts was found to be 76.0MPa with volume density of 1.94 g/cm2. Fused Quartz crucible prepared under conditions mentioned above was 800mm in length, 800mm in width and 400mm in height.

Abstract: The paper is focused on the present situation and the development of large-scale circulating fluidized bed (CFB) boilers. Several developed technology of CFB such as supercritical and ultra supercritical pressure CFB boilers for power plants, oxy-fuel CFB boiler for CO2 capture and high-density circulating fluidized bed gasifier for advanced IGCC/IGFC are introduced in this paper.

Abstract: To overcome the disadvantages of existing large-scale coordinate measurement systems about low level of automation and poor parallelism, this paper introduces a novel system which characters multi-sensor measuring network, while a single sensor measures angle via a couple of non-parallel planar laser beams rotating around a fixed shaft. The novel method for measuring angle improves automation in large-scale coordinate measurement. Furthermore, measuring network assures that measurement accuracy keeps to the same level even when the measuring range is enlarged. Measurement model and calibration are the key technologies of the system. They are the main sources of measuring errors. Therefore, to minimize the error, a practical global calibration method for the multi-sensor network system is proposed, with constructing a precise mathematical model. In this model, the parameters of the system are divided to inner and outer parts. While the inner parameters are obtained by aided instrument, the outer which means transform parameters between different sensors are figured out in spot calibration. Finally, the objective function based on transform coefficients between different sensor coordinate systems is defined and the outer parameters are optimized by bundle adjustment method. Thus, the whole system can finish global calibration by one time，and no medi-coordinate-frame is needed．Therewith，transformation time of coordinate frame decreases and calibration process is facilitated. Finally，measurement experiments are conducted with root mean square(RMS) error of not more than 0.1 mm.