Friction Behavior of High Velocity Oxygen Fuel (HVOF) Thermal Spray Coating Layer of Nano WC-Co Powder

T.Y. Cho,J.H. Yoon,K.S. Kim,W. Fang,Y.K. Joo,K.O. Song,S.J. Youn,S.Y. Hwang,H.G. Chun 한국표면공학회 2007 한국표면공학회지 Vol.40 No.4

High Velocity Oxygen Fuel (HVOF) thermal spray coating of nano size WC-Co powder (nWC-Co) has been studied as one of the most promising candidate for the possible replacement of the traditional hard plating in some area which causes environmental and health problems. nWC-Co powder was coated on Inconel 718 substrates by HVOF technique. The optimal coating process obtained from the best surface properties such as hardness and porosity is the process of oxygen flow rate (FR) 38 FMR, hydrogen FR 57 FMR and feed rate 35 g/min at spray distance 6 inch for both surface temperature 25℃ and 500℃. In coating process a small portion of hard WC decomposes to less hard W₂C, Wand C at the temperature higher than its decomposition temperature 1,250°C resulting in hardness decrease and porosity increase. Friction coefficient increases with increasing coating surface temperature from 0.55-0.64 at 25℃ to 0.65-0.76 at 500℃ due to the increase of adhesion between coating and counter sliding surface. Hardness of nWC-Co is higher or comparable to those of other hard coatings, such as A1₂O₃, Cr, Cr₂O₃ and HVOF Tribaloy 400 (T400). This shows that nWC-Co is recommendable for durability improvement coating on machine components such as high speed spindle.

Effects of Dietary Dihydropyridine Supplementation on Laying Performance and Fat Metabolism of Laying Hens

Zou, X.T.,Xu, Z.R.,Zhu, J.L.,Fang, X.J.,Jiang, J.F. Asian Australasian Association of Animal Productio 2007 Animal Bioscience Vol.20 No.10

The experiment was conducted to investigate the effects of dihydropyridine on laying performance and fat metabolism of laying hens. Five hundred and forty laying hens, 40 weeks old, were randomly allotted to three groups, each of which included four replicates of 45 hens. The groups were given a basal corn-soybean meal diet supplemented with 0, 150 mg/kg and 300 mg/kg dihydropyridine. Results showed that compared with the control group (0 mg/kg dihydropyridine), supplements of 150 and 300 mg/kg dihydropyridine increased egg production rate by 9.39% (p<0.01) and 12.97% (p<0.01), increased mean egg weight by 3% (p>0.05) and 4.8% (p>0.05), and improved feed efficiency by 9.54% (p<0.05) and 7.25% (p<0.05), respectively; The addition of 150 and 300 mg/kg dihydropyridine decreased percentage of abdominal fat by 35.4% (p<0.05) and 46.9% (p<0.05), decreased liver fat content by 32.4% (p<0.05) and 10.5% (p<0.05), increased HSL activity of abdominal fat by 39.64% (p<0.05) and 48.48% (p<0.05), increased HSL activity of liver by 9.4% (p>0.05) and 47.34% (p<0.05) and increased the content of cAMP in adenohypophysis by 14.67% (p<0.05) and 10.91% (p<0.05), respectively; The inclusion of 150 mg/kg dihydropyridine increased liver superoxide dismutase activity by 69.61% (p<0.05), and increased hepatic apoB concentration by 53.96% (p<0.05); The supplementation of 150 or 300 mg/kg dihydropyridine decreased malondialdehyde concentration of hepatic mitochondria by 30.90% (p<0.01) and 10.39% (p<0.05), respectively; Supplemented dihydropyridine had no significant effects on TG, Ch HDL-C and VLDL-C concentrations in serum; addition of 150 or 300 mg/kg dihydropyridine increased T3 levels in serum by 15.34% (p<0.05) and 11.88% (p<0.05) and decreased insulin concentration by 40.44% (p<0.05) and 54.37% (p<0.05), respectively. The results demonstrated that adding dihydropyridine had the tendency of improving very low density lipoprotein receptor (VLDLR) content in the ovary. It was concluded that dihydropyridine could improve laying performance and regulate the fat metabolism of laying hens and that 150 mg/kg dihydropyridine is the optimum dose for laying birds in practical conditions.

INFLUENCE OF INJECTION PARAMETERS ON THE TRANSITION FROM PCCI COMBUSTION TO DIFFUSION COMBUSTION IN A SMALL-BORE HSDI DIESEL ENGINE

T. FANG,R. E. COVERDILL,C.-F. F. LEE,R. A. WHITE 한국자동차공학회 2009 International journal of automotive technology Vol.10 No.3

In this paper, the influence of injection parameters on the transition from Premixed Charge Combustion Ignition (PCCI) combustion to conventional diesel combustion was investigated in an optically accessible High-Speed Direct-Injection (HSDI) diesel engine using multiple injection strategies. The heat release characteristics were analyzed using incylinder pressure for different operating conditions. The whole cycle combustion process was visualized with a high-speed video camera by simultaneously capturing the natural flame luminosity from both the bottom of the optical piston and the side window, showing the three dimensional combustion structure within the combustion chamber. Eight operating conditions were selected to address the influences of injection pressure, injection timing, and fuel quantity of the first injection on the development of second injection combustion. For some cases with early first injection timing and a small fuel quantity, no liquid fuel is found when luminous flame points appear, which shows that premixed combustion occurs for these cases. However, with the increase of first injection fuel quantity and retardation of the first injection timing, the combustion mode transitions from PCCI combustion to diffusion flame combustion, with liquid fuel being injected into the hot flame. The observed combustion phenomena are mainly determined by the ambient temperature and pressure at the start of the second injection event. The start-of-injection ambient conditions are greatly influenced by the first injection timing, fuel quantity, and injection pressure. Small fuel quantity and early injection timing of the first injection event and high injection pressure are preferable for low sooting combustion. In this paper, the influence of injection parameters on the transition from Premixed Charge Combustion Ignition (PCCI) combustion to conventional diesel combustion was investigated in an optically accessible High-Speed Direct-Injection (HSDI) diesel engine using multiple injection strategies. The heat release characteristics were analyzed using incylinder pressure for different operating conditions. The whole cycle combustion process was visualized with a high-speed video camera by simultaneously capturing the natural flame luminosity from both the bottom of the optical piston and the side window, showing the three dimensional combustion structure within the combustion chamber. Eight operating conditions were selected to address the influences of injection pressure, injection timing, and fuel quantity of the first injection on the development of second injection combustion. For some cases with early first injection timing and a small fuel quantity, no liquid fuel is found when luminous flame points appear, which shows that premixed combustion occurs for these cases. However, with the increase of first injection fuel quantity and retardation of the first injection timing, the combustion mode transitions from PCCI combustion to diffusion flame combustion, with liquid fuel being injected into the hot flame. The observed combustion phenomena are mainly determined by the ambient temperature and pressure at the start of the second injection event. The start-of-injection ambient conditions are greatly influenced by the first injection timing, fuel quantity, and injection pressure. Small fuel quantity and early injection timing of the first injection event and high injection pressure are preferable for low sooting combustion.

MOLECULAR DYNAMICS OF NANOINDENTATION WITH CONICAL CARBON INDENTERS ON GRAPHITE AND DIAMOND

T. H. FANG,Y. C. FAN,W. J. CHANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2010 NANO Vol.5 No.4

Molecular dynamics (MD) simulation of nanoindentation with a conical carbon indenter on graphite sheets and diamond is performed. The interactions of carbon indenter, graphite, and diamond atoms are described by the Tersoff–Brenner potential. Also, the Lennard–Jones potential function is employed to simulate the interactions between the indenter and the graphite and diamond atoms. The simulation results show that the maximum contact force increases with increasing conical angle due to an increase in the contact area. As the indentation velocity increases, the maximum contact force increases. However, the force decreases when the substrate temperature increases because of the weak interaction force between the atoms. Furthermore, the maximum contact force of nanoindentation with a conical indenter on the diamond was larger than that on the graphite sheets at the same indentation depth, velocity, and temperature.

Interfacial Energy in Tb<SUB>29.3</SUB>Co<SUB>70.7</SUB>/Tb<SUB>17.2</SUB>Co<SUB>82.8</SUB> Bilayer Films

Y. H. Fang,P. C. Kuo,C. T. Kuo,T. Y. Huang 한국자기학회 2007 한국자기학회 학술연구발표회 논문개요집 Vol.- No.-

High Magnetization Exchange Coupled TM-TbCo/RE-TbCo Double Layer

Y. H. Fang,P. C. Kuo,S. C. Chen,C. T. Kuo,T. Y. Huang 한국자기학회 2007 한국자기학회 학술연구발표회 논문개요집 Vol.- No.-

Static measurement of yield stress using a cylindrical penetrometer

Uhlherr, P.H.T.,Guo, J.,Fang, T.N.,Tiu, C. The Korean Society of Rheology 2002 Korea-Australia rheology journal Vol.14 No.1

A novel and simple method using a cylindrical penetrometer is being developed for the measurement of yield stress. The principle of this technique is based on the measurement of the static equilibrium of a falling penetrometer in a yield stress fluid. The yield stress is simply determined by a balance of forces acting on the penetrometer. The yield stress of Carbopol gels and $TiO_2$ suspensions has been measured using this method. The results are in reasonable agreement with the values from conventional methods. The effects of the dimensions and weight of the penetrometer have been examined. The long-term behaviour was also observed. No measurable creep was seen and equilibrium was found to be very quickly established. The cylindrical penetrometer technique promises to be a simple, quick and reliable static method for the measurement of yield stress.

The Additivity of True or Apparent Phosphorus Digestibility Values in Some Feed Ingredients for Growing Pigs

Fang, R.J.,Li, T.J.,Yin, F.G.,Yin, Y.L.,Kong, X.F.,Wang, K.N.,Yuan, Z.,Wu, G.Y.,He, J.H.,Deng, Z.Y.,Fan, M.Z. Asian Australasian Association of Animal Productio 2007 Animal Bioscience Vol.20 No.7

Two experiments were conducted to determine the additivity of apparent or true digestibility of phosphorus (P) in soybean meal (SBM), peas, faba beans, corn, oats, broken rice meal, rough rice meal, buckwheat, and sorghum for growing pigs. Chromic oxide (0.3%) was used as a digestion marker in both experiments. Each experiment lasted for 12 d, which consisted of a 7-d dietary adaptation period followed by a 5-d fecal collection period. Experiment 1 involved 6 diets: the SBM-based control diet; 4 diets with corn, oats, rough rice meal and broken rice meal substituted for SBM; and an additional diet with a representative mixture of the 5 ingredients. In Experiment 2, 6 diets were prepared similarly, except that the tested ingredients besides SBM were faba beans, peas, buckwheat, and sorghum. In each experiment, six barrows with an initial average individual BW of 20.5 kg were fed one of the six diets according to a $6{\times}6$ Latin square design. The apparent and true P digestibility values for the nine tested ingredients were determined by the substitution method. There were no differences (p>0.05) between the determined and the predicted true P digestibility values for the mixture of ingredients in Experiments 1 and 2. However, the determined and the predicted apparent P digestibility values for the mixture of ingredients differed (p = 0.059) in Experiment 1, but not in Experiment 2. These results indicate that true P digestibility values are additive in ingredients containing low levels of phytate phosphorus and anti-nutritional factors, whereas the apparent P digestibility values are not always additive in single feed ingredients for growing pigs.

Material Transportation Problems in Construction Projects under an Uncertain Environment

Fang Yan,Jiuping Xu,Bernard T Han 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.7

Uncertainty is prevalent and unavoidable in business operations. This paper presents a mathematical model for the optimal routing of shipping raw materials to customers that requires simultaneous pickup and delivery with soft time windows for travel time in a fuzzy random environment. It minimizes total traveling time while maximizing customer satisfaction and meeting constraints characterized by fuzziness and randomness in pickup and travel time. The model is strong NP-hard. Through embedding of customer satisfaction as a constraint and converting fuzzy random variables into deterministic ones using expected values, a viable algorithm is developed using the Global-Local-Neighbor Particle Swarm Optimization (GLNPSO) technique, and tested by solving a real routing problem faced by a large construction project in China. Results are encouraging, both in solution quality and potential savings, to justify the solution method and model formulation.

Multiannual Top-Down Estimate of HFC-23 Emissions in East Asia

Fang, X.,Stohl, A.,Yokouchi, Y.,Kim, J.,Li, S.,Saito, T.,Park, S.,Hu, J. American Chemical Society 2015 Environmental science & technology Vol.49 No.7

<P>Trifluoromethane (CHF<SUB>3</SUB>, HFC-23), with a 100-year global warming potential (GWP) of 12400, is regulated under the Kyoto Protocol. HFC-23 emissions in East Asia, especially in China, are currently thought to represent the majority of global HFC-23 emissions. This study provides both a bottom-up emission inventory and the multiannual top-down estimate of HFC-23 emissions in East Asia during 2007–2012. The new bottom-up inventory yields improved simulated HFC-23 mixing ratios compared to previous bottom-up inventories. The top-down estimate uses inverse modeling to further improve the model-measurement agreement. Results show that China contributed 94–98% of all HFC-23 emissions in East Asia. Annual a posteriori emissions from China were around 6.3 Gg/yr during the period 2007–2010 after which they increased to 7.1 ± 0.7 Gg/yr in 2011 and 8.8 ± 0.8 Gg/yr in 2012. For the first time, this study also provides a top-down estimate of HFC-23/HCFC-22 (chlorodifluoromethane, CHClF<SUB>2</SUB>) coproduction ratios in non-CDM (Clean Development Mechanism) HCFC-22 production plants as well as in all HCFC-22 production plants in China.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/esthag/2015/esthag.2015.49.issue-7/es505669j/production/images/medium/es-2014-05669j_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/es505669j'>ACS Electronic Supporting Info</A></P>