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Tangshan, China

Huang L.,Beijing University of Technology | Huang L.,Beijing Institute of Technology | Liu Z.,Beijing University of Technology | Liu Y.,Beijing University of Technology | And 3 more authors.
Experimental Thermal and Fluid Science | Year: 2012

The effect of contact angle on water droplet freezing process on a cold flat surface under natural convection conditions was experimentally investigated. A series of hydrophobic surfaces with different contact angles were prepared by solution immersion. The contact angles of these surfaces were varied from 97.2° to 154.9°. Comparative observations of water droplet freezing processes were carried out on both plain copper surface and these hydrophobic surfaces under the same conditions. The experimental results showed that the contact angle has a strong influence on the water droplet freezing time. The larger the contact angle is, the longer the freezing time. The frost crystals growth on the droplet surface that frozen on the hydrophobic surface is faster and presents a pattern that is more dendritic than that on the plain copper surface. © 2012 Elsevier Inc.

Guo C.,China Agricultural University | Guo C.,Tangshan University | Zong Z.,China Agricultural University | Zhang X.,China Agricultural University | And 2 more authors.
Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery | Year: 2015

There are large differences between the actual colour of fruit trees canopy and the point cloud from the ground three-dimensional laser scanner in the complex outdoors environment. In order to solve this problem, a new color correction method for color correction was proposed. Firstly, the Pearson coefficient and Spearman correlation coefficient were calculated to make sure that there are relationships among the R, G, B values of the scanning spot and the R, G, B values of the 24-Patch Color Checker Chart Classic, the solar radiation values, the angle θ between 24-Patch Color Checker Chart Classic and the earth, scan quality, and light direction variables. And then, with confidence level of 95%, an R, G, B components multiple regression model was established by using the dual-sifting stepwise regression in statistical method. Lastly, the model was used to correct three-dimensional points cloud colors. The experiment results show that, using the three-dimensional point correlation regression model, the correlation coefficient between the three-dimensional point cloud color R, G, B value and the real R, G, B values increased from less than 0.69 to above 0.90 after correction, and color-corrected standard deviation fell significantly from above 50% to below 13%. The method could be used to provide a theoretical basis for terrestrial laser scanning to obtain more accurate three-dimensional color points cloud. © 2015, Chinese Society for Agricultural Machinery. All right reserved.

Gou Y.-J.,Beijing University of Technology | Gou Y.-J.,Tangshan University | Liu Z.-L.,Beijing University of Technology
Kung Cheng Je Wu Li Hsueh Pao/Journal of Engineering Thermophysics | Year: 2012

A new cooling concept for high power LED by combining the heat release of high power LED with two-phase heat transfer heat pipes was proposed, and in this study a series of heat pipes with specific fins structure were developed. From the experimental results obtained, it is found that the new heat pipe heat exchanger is of high heat dissipation capacity and compact construction that will meet the demand of high power LED cooling. The new heat pipe heat exchangers with different fin shapes have different efficiency of heat dissipation and the new heat exchanger with outwards-radiate fins has the best heat dissipation performance. It is also shown that the heat dissipation performance of the heat pipe heat exchanger changes with the position angle. The effects of the numbers of heat pipes and the fin materials on the heat dissipation performance of the whole cooling system were also carried out.

Gou Y.-J.,Beijing University of Technology | Gou Y.-J.,Tangshan University | Liu Z.-L.,Beijing University of Technology | Zhang G.-M.,Beijing University of Technology | Li Y.-X.,Beijing University of Technology
Kung Cheng Je Wu Li Hsueh Pao/Journal of Engineering Thermophysics | Year: 2014

In the present work, multi-walled carbon nanotubes (MWCNTs) are used as additives for enhancing the thermal conductivity of the widely-used silicon grease as thermal interface materials (TIMs). The effects of the MWCNTs length and surface treatment on the silicon grease conductivity are studied. The results show that the MWCNT length has strong influences on the thermal performance of the grease with MWCNT additives. The equivalent thermal conductivity of the composite layer of the grease and the solid surfaces increases as the MWCNT length decreases. Only the length of MWCNTs is short enough, their addition can improve the thermal performance of the common silicon grease. Surface treatment on MWCNTs can improve the thermal performance of the grease. Through transmission electron microscope (TEM) observation it is found that after the modification of the short MWCNTs the MWCNT entanglement phenomenon in the mother silicon grease is weakened and the MWCNTs are dispersed more uniformly.

Ren G.F.,Tangshan Design and Research Institute of Buildings | Qiao J.S.,Tangshan University
Applied Mechanics and Materials | Year: 2013

This paper takes Nanhu project of Tangshan City under the soil condition of foundation pit excavation as an example. A model is established to research on the mechanical behavior effect of around composite foundation of CFG under soil lateral displacement by using ANSYS finite element software. The model analyzes the distribution law of horizontal displacement, stress of pile, soil between piles of CFG composite foundation under soil lateral displacement. Put forward a calculation formula of pile displacement by considering excavation depth, excavation distance. © (2013) Trans Tech Publications, Switzerland.

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