Papers by Author: Yong Tian Wang

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Authors: Yong Tian Wang
Abstract: In this paper we describe the synthesis of nanocrystalline boron nitride (BN) with a hollow morphology by the reaction of NH4BF4 and NaNH2 at 500 oC for 24h. Characterized by XRD, FTIR, XPS, TEM, and EDXA spectra, the composition and morphology of the products were confirmed. The possible formation mechanism was also discussed.
Authors: Yong Tian Wang
Abstract: Thermal reduction process has been employed for the synthesis of carbon nanotubes (CNTs), during which ether was used as carbon source and metallic sodium play a role of reducing agent. The obtained CNTs have a diameter range of 50 nm and length range of 200-1000 nm. The as-prepared product was characterized by X-ray powder di.raction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED).
Authors: Xia Hui Gui, Gan Chen, Jiong Tian Liu, Yi Jun Cao, Yong Tian Wang
Abstract: As certain refractory molybdenum with degree high oxidation and high argillization, on the premise of molybdenum concntrate recovery rate, in order to increase tenor of molybdenum concntrate, we use cyclonic static micro-bubble flotation column as concentration equipment. We used two concentrate courses to replace flotation machine eight concentrate courses. It showed that, in the condition of same recovery rate, tenor of molybdenum concntrate was 26.16%, rising by 8%. Using processes of flotation machine eight concentrate courses - concentrate regrinding - flotation column two concentrate courses, tenor of molybdenum concntrate was 39.33% and the recovery rate was of 8%. The results showed that, by increasing the degree of monomer dissociation of molybdenum ores, cyclonic static micro-bubble flotation column has higher capability in recovering and selecting ores of -400 mm size fraction. The high argillization resulting from the regrinding and unsuppressed gangue minerals are the main factors affecting the tenor of ore concentrate.
Authors: Xia Hui Gui, Jiong Tian Liu, Xiu Xiang Tao, Yi Jun Cao, Yong Tian Wang
Abstract: As for certain high ash and difficult floatable fine coal, the coal quality characteristic is the frangible and easyly-clayed main gangue mineral kaolinite, and the high content of fine-grade and intermediate density grade materials. In order to reduce tiny slimes pollution and to increase quality and recovery rate of concentrate, we used cyclonic-static micro-bubble flotation column and XFD-3 flotation machine to experiment on separation process. It probed into re-concentration after grinding rough refined coal, classified flotation process and selective agglomeration-flotation process these three technical processes. The comparison of flotation machine test result showed that, using the flotation column as separation equipment, process of re-concentration after grinding rough refined coal could obtain the best refined coal accumulation index. When medicaments dosage is kerosene 800 g/t, GF 300 g/t, and sodium hexametaphosphate 1500g/t, refined coal production rate of flotation column is 59.47% and ash content is 10.63%.
Authors: Hong Liu, Jin Guo Li, Yong Tian Wang
Abstract: Thermal field analysis for automotive lamps is a complicated thermodynamics problem. According to the features of structure and lighting process of automotive lamps, a simple and convenient model is put forward here for analyzing their thermal field. Under certain assumptions, it simplifies the complicated geometrical structure to the relative simple cavities and only considers the influence of thermal conduction and thermal radiation as main forms of heat transfer for thermal field of the lamps. The consistency of numerical analysis and actual test demonstrates that this modeling method calculates thermal field of the lamps quickly and perfectly, and indicates its practical signification.
Authors: Bo Yang, Guo Fan Jin, Yong Tian Wang
Abstract: NURBS surface representation, combined with Differential Evolution (DE), enables us to perform automated non-imaging reflector design. The overall result is a simple automated nonimaging reflector design technique and only a little data such as desired illuminance distribution and searching limits are needed. Merit functions specific to non-imaging reflector design are presented. Using different merit functions, the generated illuminance distribution can be uniform as well as concentrated. DE is performed to obtain the reflector that generates the desired illuminance distribution. The photometric distributions are calculated through Monte-Carlo ray tracing and the illuminance value is used to calculate the merit function value. The validity of the proposed approach is demonstrated by optimization examples. Almost the same uniform illuminance distribution can be obtained using the algorithm proposed in this paper as that obtained by edge-raymethod. A concentrated illuminance distribution can also be generated using the algorithm proposed.
Authors: Hao Bo Cheng, Jing Feng Zhi, Suet To, Yong Tian Wang
Abstract: This paper proposes a novel wheel-shaped grinding/polishing tool, which is designed to be controlled on both the self-rotation around its axis and the co-rotation around vertical axis Z at the specified speeds respectively. Therefore, the surface material of the workpiece can be removed by virtue of self-rotating motion. On the other hand, the co-rotating motion will also change the manufacturing orbit continually. To analyze the characteristics of the tool, material removal in the manufacturing zone on the workpiece surface is first established through theoretical modeling. Subsequently, a good evaluating method, i.e. power spectral density, for analyzing the frequency spectrum features of material removal function in computer-controlled optical grinding and polishing is introduced in detail. By simulation, the power spectral density of the material removal function was cut into several parts, some frequency with low amplifies of material removal function were removed, and the modified material removal function reflected the actual processing status, which was helpful in removing some residual high frequency errors on the surface of the workpiece. Finally, the high amplitude such as at high frequency of 110mm-1 and 210mm-1 was reserved and some other low amplitude frequencies were removed.
Authors: De Wen Cheng, Yong Tian Wang, M.M. Talha, Jun Chang
Abstract: To analyze the effects of fabrication and alignment errors on optical systems with complex apertures such as a segmented telescope, a visual basic routine (VBR) is developed using CODE V’s COM interface. One of the eminent features of this VBR is its graphical user interface (GUI). The GUI facilitates the user to model different types of segmentations quickly and precisely. The input parameters describe the basic shapes of the segments (polygon or sector), the chamfers at their corners, and the gaps between them. Fabrication errors (i.e. surface errors and alignment errors such as decenters and tilts for each segment) can also be introduced easily and effectively through the GUI. Geometrical and diffraction-based analyses can then be performed to study and analyze the effects of these errors on the imaging quality of the optical system. Results of tolerance analysis are presented for a test system, which require a very stringent tolerance to be placed on the discrepancy among the radii of curvature for different segments. In short, the VBR is a user friendly and a flexible tool with its application scope in designing complex aperture optical systems.
Authors: Xia Hui Gui, Jiong Tian Liu, Xiu Xiang Tao, Yi Jun Cao, Yong Tian Wang
Abstract: Aim at high-to-float high-ash fine coal with large content of granules, in order to reduce pollution of carried fine slime to quality of concentrate coal, soluble glass, sodium hexametaphosphate and cornstarch these three kinds of regulators were choosen to carry out flotation reducing ash experiment. Result showed that, cause of poor selectivity of fine coal is mainly small quality, big surface area and the poor dispersion of fine coal. When sodium hexametaphosphate dosage is 1500g/t, the kerosene dosage is 370g/t, the foam beater GF dosage is 150g/t, production rate of concentrate coal is 57.69%,and ash content of concentrate coal is 12.04%. Under the same condition, separation index of sodium hexametaphosphate as regulator is superior to cornstarch and soluble glass.
Authors: Yong Tian Wang
Abstract: Since the early 1980s, great progress has been made in microbubble column flotation technology. As one of the important mineral processing methods, the application and development of this technology in China are summarized in this paper from four respects. Firstly, a patented cyclone- static microbubble separation method was proposed to overcome the notable problems mentioned in the previous flotation columns. Secondly, microbuble column flotation was introduced to separate the high ash as well hard-to-separate coal slime generated from dense medium processes. The characteristics of the microbubble column, and the flotation process for fine coal and the high ash coal separation was analyzed. Thirdly, the application of microbubble column flotation in China was detailed introduced, especially the characteristics of series microbubble column flotation equipment, and efficient column type coal slime separation crafts were discussed. The application of microbubble column flotation particularly in low ash content coal preparation, and discarded coal slime processing technology were presented. Finally, microbubble column flotation has been extended to non-coal mineral processing, such as magnetite concentrate upgrading (concentration iron and removing silicon), sulfide copper mine separation, white tungsten flotation, etc., the related research was briefly introduced in this paper as well.
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