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Influences of the Welding Heat Input and the Repeated Repair Welding on Ti–3Al–2.5V Titanium Alloy

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Acta Metallurgica Sinica(English Letters) 2015年第6期28卷 684-691页

作者： Hui-Jun yi Yong-Jun lee Kwang-O lee School of Mechanical Engineering Pusan National University

The primary purpose of this study was to determine the effects of gas tungsten arc welding heat input on the high-temperature tensile properties, toughness, and microstructural features of titanium alloy Ti-3A1-2.5V. The secondary objective was to examine the effect of the repeated repair welding on the properties of the alloy. It was also found that the mechanical properties progressively decreased with increasing the repair welding cycles, especially in the case of the weldment after the first welding repair. It was observed that the sizes of the acicular and prior β grain boundaries as well as the volume fraction of the acicular phases increased with increasing the welding heat input. In addition, the amount and size of the acicular a1 phases were found to increase with increasing the repair welding cycles.

关键词： Ti-3AI-2.5V Repair welding Heat input Tensile properties Microstructure

Friction and wear of textured surfaces produced by 3D printing

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Science China(Technological Sciences) 2017年第9期60卷 1400-1406页

作者： HONG yi ZHANG Peng lee Kwang-Hee lee Chul-Hee Department of Mechanical Engineering Inha University Incheon 402-751 Korea

Surface texture patterns have great potential for improving tribological performance in terms of reducing friction and wear. The most common methods for surface texatring are laser and injection molding. The 3D printing method is also used to build parts, patterns, and molds that feature fine details for a wide range of applications because texture manufacturing by 3D printing is faster, more flexible, and less expensive than traditional techniques. To date, there has been no research on textured surfaces produced by 3D printing. Therefore, a new fabrication method using 3D printing to improve friction and wear properties is a topic worth exploring. In this study, a reciprocating friction tester was used to evaluate the friction and wear properties of different surface textures produced by 3D printing. The surface of specimens was examined by electron microscope and scanning electron microscope before and after the test. The results show that surface texturing can be applied to 3D printed parts to improve their friction and wear performance.

关键词： three-dimensional (3D) printing texture friction wear

The Boundedness of Calderón-Zygmund Operators by Wavelet Characterization

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Acta Mathematica Sinica,English Series 2012年第6期28卷 1237-1248页

作者： Cheng-Cong HUNG Ming-yi lee Department of Applied Mathematics National Chiao Tung University Department of Mathematics National Central University

This article deals with the boundedness properties of Calderdn-Zygmund operators on Hardy spaces Hp（Rn）. We use wavelet characterization of H^P（R^n） to show that a Calderon-Zygmund operator T with T＊1 =0 is bounded on H6P（R^n）, n/n＋ε zju. edu. cn 〈 p 〈 1, where ε is the regular exponent of kernel of T. This approach can be applied to the boundedness of operators on certain Hardy spaces without atomic decomposition or molecular characterization.

关键词： Calderdn Zygmund operators Hardy spaces para-product operators

Non-conventional modeling of extreme significant wave height through random sets

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Acta Oceanologica Sinica 2014年第7期33卷 125-130页

作者： ZHANG yi LAM Jasmine Siu lee Division of Infrastructure Systems and Maritime Studies School of Civil and Environmental EngineeringN1-B1a-25 Nanyang Technological UniversitySingapore Division of Infrastructure Systems and Maritime Studies School of Civil and Environmental EngineeringN1-01b-43 Nanyang Technological UniversitySingapore

The analysis and design of offshore structures necessitates the consideration of wave loads. Realistic modeling of wave loads is particularly important to ensure reliable performance of these structures. Among the available methods for the modeling of the extreme significant wave height on a statistical basis, the peak over threshold method has attracted most attention. This method employs Poisson process to character- ize time-varying properties in the parameters of an extreme value distribution. In this paper, the peak over threshold method is reviewed and extended to account for subjectivity in the modeling. The freedom in selecting the threshold and the time span to separate extremes from the original time series data is incorpo- rated as imprecision in the model. This leads to an extension from random variables to random sets in the probabilistic model for the extreme significant wave height. The extended model is also applied to different periods of the sampled data to evaluate the significance of the climatic conditions on the uncertainties of the parameters.

关键词： offshore engineering extreme value distribution wave height peak over threshold randomset Pareto distribution

Portable Dynamic Positioning Control System on A Barge in Short-Crested Waves Using the Neural Network Algorithm

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China Ocean Engineering 2013年第4期27卷 469-480页

作者： FANG Ming-chung lee Zi-yi Department of Systems and Naval Mechatronic Engineering National Cheng Kung University

This paper develops a nonlinear mathematical model to simulate the dynamic motion behavior of the barge equipped with the portable outboard Dynamic Positioning （DP） system in short-crested waves. The self-tuning Proportional- Derivative （PD） controller based on the neural network algorithm is applied to control the thrusters for optimal adjustment of the barge position in waves. In addition to the wave, the current, the wind and the nonlinear drift force are also considered in the calculations. The time domain simulations for the six-degree-of-freedom motions of the barge with the DP system are solved by the 4th order Runge-Kutta method which can compromise the efficiency and the accuracy of the simulations. The technique of the portable alternative DP system developed here can serve as a practical tool to assist those ships without being equipped with the DP facility while the dynamic positioning missions are needed.

关键词： neural network PD controller dynamic positioning short-crested wave

A one-step method for producing microencapsulated phase change materials

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Particuology 2010年第6期8卷 588-590页

作者： yi Jin Waipeng lee Zenfira Musina Yulong Ding Institute of Process Engineering Chinese Academy of Sciences Beijing China Institute of Particle Science & Engineering University of Leeds Clarendon Road LS2 9JT Leeds UK

This short communication reports our recent work on the synthesis and characterisation ofmicrocapsules of phase change materials using silica as the shell material through a one-step method. The method uses no surfactants or dispersants for stabilising the capsules. The results show that the one-step method allows the tuning of the size and polydispersity of the capsules, and the use of different core materials. Analyses of the capsules show that they contain about 65% phase change materials. The results also suggest no need for a stabilising agent due to self-stabilisation by the amine groups. Further work is underway to investigate the mechanical and thermal properties of the microcapsules and the scale-up of the method.

关键词： Microencapsulation Phase change materials One-step method Thermal energy storage

Quantifying and managing regional greenhouse gas emissions: Waste sector of Daejeon, Korea

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Journal of Environmental Sciences 2014年第6期26卷 1249-1259页

作者： Sora yi Heewon Yang Seung Hoon lee Kyoung-Jin An Department of Urban Planning Research Daejeon Development Institute Department of Environmental Engineering Anyang University Faculty of Science & Technology The Technological and Higher Education Institute of Hong KongNew Territories Hong Kong China

A credible accounting of national and regional inventories for the greenhouse gas （GHG） reduction has emerged as one of the most significant current discussions. This article assessed the regional GHG emissions by three categories of the waste sector in Daejeon Metropolitan City （DMC）, Korea, examined the potential for DMC to reduce GHG emission, and discussed the methodology modified from Intergovernmental Panel on Climate Change and Korea national guidelines. During the last five years, DMC＇s overall GHG emissions were 239 thousand tons C02 eq./year from eleven public environmental infrastructure facilities, with a population of 1.52 million. Of the three categories, solid waste treatment/disposal contributes 68%, whilst wastewater treatment and others contribute 22% and 10% respectively. Among GHG unit emissions per ton of waste treatment, the biggest contributor was waste incineration of 694 kg CO2 eq./ton, followed by waste disposal of 483 kg CO2 eq./ton, biological treatment of solid waste of 209 kg CO2 eq./ton, wastewater treatment of 0.241 kg CO2 eq./m3, and public water supplies of 0.067 kg CO2 eq./m3. Furthermore, it is suggested that the potential in reducing GHG emissions from landfill process can be as high as 47.5% by increasing landfill gas recovery up to 50%. Therefore, it is apparent that reduction strategies for the main contributors of GHG emissions should take precedence over minor contributors and lead to the best practice for managing GHGs abatement.

关键词： Solid waste disposal biological treatment of solid waste waste incineration wastewater treatment public water supply

Carbonyl compounds in dining areas,kitchens and exhaust streams in restaurants with varying cooking methods in Kaohsiung,Taiwan

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Journal of Environmental Sciences 2016年第3期28卷 218-226页

作者： Jen-Hsuan Cheng yi-Shiun lee Kang-Shin Chen Institute of Environmental Engineering "National" Sun Yat-Sen University

Eighteen carbonyl species in C_1-C_（10） were measured in the dining areas,kitchens and exhaust streams of six different restaurant types in Kaohsiung,southern *** results in the dining areas show that Japanese barbecue（45.06 ppb） had the highest total carbonyl concentrations（sum of 18 compounds）,followed by Chinese hotpot（38.21 ppb）,Chinese stir-frying（8.99 ppb）,Western fast-food（8.22 ppb）,Chinese-Western mixed style（7.38 ppb）,and Chinese buffet（3.08 ppb）,due to their different arrangements for dining and cooking spaces and different cooking *** average,low carbon-containing species（C_1-C_4）,e.g.,formaldehyde,acetaldehyde,acetone and butyraldehyde were dominant and contributed 55.01%-94.52%of total carbonyls in the dining areas of all ***,Chinese-Western mixed restaurants（45.48 ppb） had high total carbonyl concentrations in kitchens mainly because of its small kitchen and poor ***,high carbon-containing species（C_5-C_（10）） such as hexaldehyde,heptaldehyde and nonanaldehyde（16.62%-77.00%of total carbonyls） contributed comparatively with low carbon-containing compounds（23.01%-83.39%of total carbonyls） in ***,Chinese stir-frying（132.10 ppb）,Japanese barbecue（125.62 ppb）,Western fast-food（122.67 ppb）,and Chinese buffet（119.96 ppb） were the four restaurant types with the highest total carbonyl concentrations in exhaust streams,indicating that stir-frying and grilling are inclined to produce polluted *** risk assessments indicate that Chinese hotpot and Japanese barbecue exceeded the limits of cancer risk（10^（-6）） and hazard index（=1）,mainly due to high concentrations of *** other four restaurants were below both limits.

关键词： Carbonyl compounds Restaurant Exhaust stream Health effect

Bojungbangdocktang inhibits vascular endothelial growth factor induced angiogenesis via blocking the VEGF/VEGFR2 signaling pathway in human umbilical vein endothelial cells

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Chinese Science Bulletin 2009年第2期54卷 227-233页

作者： JANG Yu-Sung lee Eun-Ok lee Hyo-Jung lee Hyo-Jeong KIM Kwan-Hyun WON Sook-Hyun lee Jae-Dong AHN Kwang Seok AHN Kyoo Seok KIM Jung-Hyo YU Young-beob KIM Sung-Hoon College of Oriental Medicine Kyunghee University 1 Hoegidong Dongdaemungu Seou1130-701 Republic of Korea Chosun Nursing College 375 Seosuk-dong Dong-gu Gwangju 501-759 Korea Department of Herbal Pharmaceutical Korea Institute of Oriental Medicine Jeonmin dong Youseonggu Daejeon 305-811 Republic of Korea

Oriental herbal medicines have been widely used for the prevention or treatment of various diseases including cancer in Asia. However, to prove their chemo preventive efficacies in modern times, scientific evidence for those herbal medicines is required. Thus, in the present study, an effective herbal cocktail Bojungbangdocktang (BJBDT) was investigated to elucidate antiangiogenic mechanism in vitro and in vivo. BJBDT significantly inhibited vascular endothelial growth factor (VEGF) induced proliferation in HUVECs at nontoxic concentrations, despite weak cytotoxicity against human umbilical vein endothelial cells (HUVECs). BJBDT also significantly suppressed VEGF-induced migration and tube formation of HUVECs. Furthermore, BJBDT treatment resulted in pale color and low hemoglobin level in Matrigel plugs, as well as dark red color and high hemoglobin level in untreated control. Interestingly, BJBDT specifically inhibited the binding of VEGF to vascular endothelial growth factor receptor 2 (VEGFR2), but not VEGFR1. In addition, friedelin, formononetin, ginsenoside Rb1, naringin, atractyloside, diosgenin, and allantonin were identified from BJBDT by high-performance liquid chromatography (HPLC) analysis as a quality of control. Taken together, these results suggest that BJBDT is a potent angiogenesis inhibitor blocking the VEGF/VEGFR2 signaling pathway in HUVECs.

关键词：血管新技术人大动脉内皮细胞 HUVECs VEGFR2