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Butt-welding Residual Stress of Heat Treatable Aluminum Alloys

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Journal of Materials Science & technology 2007年第2期23卷 217-222页

作者： C.M. Cheng department of Industrial Education National Taiwan Normal University Taipei Taiwan China　

This study, taking three types of aluminum alloys 2024-T351, 6061-T6 and 7075-T6 as experimental materials, conducted single V-groove GTAW （gas tungsten arc welding） butt-welding to analyze and compare the magnitude and differences of residual stress in the three aluminum alloys at different single V-groove angles and in restrained or unrestrained conditions. The results show that the larger the grooving angle of butt joint, the higher the residual tensile stress. Too small grooving angle will lead to dramatic differences due to the amount of welding bead filler metal and pre-set joint geometry. Therefore, only an appropriate grooving angle can reduce residual stress. While welding, weldment in restrained condition will lead to a larger residual stress. Also, a residual stress will arise from the restraint position. The ultimate residual stress of weldment is determined by material yield strength at equilibrium temperature. The higher the yield strength at equilibrium temperature, the higher the material residual stress. Because of its larger thermal conductivity, aluminum alloy test specimens have small temperature differential. Therefore, the residual tensile stress of all materials is lower than their yield strength.

关键词： Residual stress Hole-drilling strain-gage method Aluminum alloy Single-V groove

Sub-micron-structure machining on silicon by femtosecond laser

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中国有色金属学会会刊：英文版 2009年第B09期19卷 171-177页

作者： Hung-Yin TSAI Shao-Wei LUO Chih-Wei WU Shing-Hoa WANG department of Power Mechanical Engineering National Tsing Hua University department of Mechanical and mechatronic Engineering National Taiwan Ocean University

Sub-micron-structure machining on silicon substrate was studied by direct writing system of femtosecond laser with the central wavelength of 800 nm, pulse duration of 120 fs and repetition rate of 1 kHz. Three kinds of experiments were conducted: 1) the effect of photoresist on silicon; 2) machinability of different orientations of silicon; and 3) the size of micro-structure and the cross-section shape. Photoresist SU8 was coated onto silicon substrates in thicknesses of 100 μm. SU8 remained on the silicon substrate while the silicon under the machined SU8 was removed after laser machining. Orientations of (100), (110), and (111) silicon substrates were machined with the laser power of 60 μW and the scanning speed of 3 mm/min. Spike morphologies were observed on all three orientations of silicon substrates without obvious directional difference of these spikes on different silicon substrates. In addition, the ablation threshold energies were also similar. In the consideration of ablation energy, one numerical model of the machining parameters has been proposed to simulate the cross-section of the micro-structure. The predicted shape by simulation can fit the profile of the cross-section shape well.

关键词：亚微米结构激光加工硅基底飞秒激光直接写入断面形状微观结构模拟预测

Hot Cracking in AZ31 and AZ61 Magnesium Alloy

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Journal of Materials Science & technology 2011年第7期27卷 633-640页

作者： C.J. Huang C.M. Cheng C.P. Chou F.H. Chen department of Mechanical Engineering National Chiao Tung University Hsinchu 300 Taiwan China department of Industrial Education National Taiwan Normal University Taipei 106 Taiwan China

This paper examined the impact of the number of thermal cycles and augmented strain on hot cracking in AZ31 and AZ61 magnesium alloy. Statistical analyses were performed. Following observation using a scanning electron microscope （SEM）, an energy dispersive spectrometer （EDS） was used for component analysis. Results showed that Al content in magnesium alloy has an effect on hot cracking susceptibility. In addition, the nonequilibrium solidification process produced segregation in Al content, causing higher liquid Mg-alloy rich Al content at grain boundaries, and resulting into liquefied grain boundaries of partially melted zone （PMZ）. In summary, under multiple thermal cycles AZ61 produced serious liquation cracking. AZ61 has higher （6 wt%） Al content and produced much liquefied Mg17Al12 at grain boundaries under multiple thermal cycles. The liquefied Mg17Al12 were pulled apart and hot cracks formed at weld metal HAZ due to the augmented strain. Since AZ31 had half the Al content of AZ61, its hot-cracking susceptibility was lower than AZ61. In addition, AZ61 showed longer total crack length （TCL） in one thermal cycle compared to that in three thermal cycles. This phenomenon was possibly due to high-temperature gasification of Al during the welding process, which resulted in lower overall Al content. Consequently, shorter hot cracks exhibited in three thermal cycles. It was found the Al content of AZ31 and AZ61 can be used to assess the hot-cracking susceptibility.

关键词： Varestraint test Thermal cycles Hot-cracking susceptibility Gas tungsten arc welding (GTAW) AZ31 AZ61

Decomposition of formaldehyde by EPD photocatalyst filters in HVAC

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Particuology 2011年第5期9卷 497-501页

作者： Chien-Chih Chen Ching-Song Jwo Tun-Ping Teng Graduate Institute of Mechanical and Electrical Engineering National Taipei University of Technology Taipei. Taiwan China department of Energy and Refrigerating Air Conditioning Engineering. national Taipei university of technology Taipei Taiwan China department of Industrial Education. national taiwan normal university Taipei Taiwan China

This study used electrophoretic deposition （EPD） to apply titanium oxide （TiO2） coating on stainless steel filters and investigated the effectiveness of photocatalytic oxidation of formaldehyde by TiO2 under various conditions of heating ventilation air conditioning （HVAC）. The results showed photocatalytic efficiency could reach 35,59% at 21 ℃ and 36.39% at 26℃ with 7 photocatalyst filters and 5 UVC lamps, the overall efficiency of formaldehyde removal of 52.37% at 21 ℃, and 56.8% at 26 ℃, By all experimental data can be found that the temperature for the photocatalytic performance is not obvious in the range of this study.

关键词： Electrophoretic deposition (EPD) TiO2 Filter HVAC

Modelling Design of Color Graphics Books Using Visual Vocabulary Based on Children’s Color Language Preferences

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Computer Modeling in Engineering & Sciences 2022年第2期130卷 1171-1192页

作者： Wanni Xu Huasen Xu Xingyu Guo department of Fine Arts National Taiwan Normal UniversityTaipeiTaiwanChina department of Civil Engineering Shanghai Normal UniversityShanghaiChina department of Exhibition Management Macao University of Science and TechnologyTaipaMacaoChina

Color language has important meaning for children’s picture *** children’s preferences in terms of color language will be helpful when designers model computerized picture books in order to adapt to children’s visual senses and effectively stimulate children’s interest in *** this study,we aimed to further explore the general characteristics of children’s preference for colors,color depth and color matching forms in picture *** the study,256 children between the ages of three and six were selected and divided into four *** to the implementation needs of the children’s color preference test,these childrenwere asked to complete a series of tasks so that their choices in the tasks could subsequently be *** tasks included making the following choices:selecting their preferred colors from nine options(red,orange,yellow,green,cyan,blue,purple,black and white);selecting their preferred color brightness fromthree different color shades;and indicating their preferences in relation to complementary colors,matching colors and pure *** experimental results showed that children aged between three and six mainly favor red,blue and yellow,and colors with a high degree of *** children grow older,boys tend to prefer blue,and girls tend to prefer pink,with red remaining the favorite color of both *** for complementary colors,matching colors and solid colors,three-to six-year-old children prefer solid *** conclusion,it seems that color language preferences in children between the ages of three and six are very similar,which could be of use when designing children’s picture books to match their visual vocabulary and psychological cognition.

关键词： Modelling design child psychology color language picture book design visual vocabulary

Pressure drop of TiO_2 nanofluid in circular pipes

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Particuology 2011年第5期9卷 486-491页

作者： Tun-Ping Teng Yi-Hsuan Hung Ching-Song Jwo Chien-Chih Chen Lung-Yue Jeng department of Industrial Education National Taiwan Normal University Taipei City 10610 Taiwon China department of Energy and Refrigerating Air-Conditioning Engineering National Taipei University of Technology Toipei City 10608 Taiwan China Graduate Institute of Mechanical and Electrical Engineering National Taipei University of Technology Taipei City 10608 Taiwan China

This paper discusses the pressure drop in circular pipes of TiO2/water nanofluid for both laminar and turbulent flows at different temperatures and TiO2 weight fractions. This study shows that TiO2/water nanofluid causes enhancement, but temperature rise reduces pressure drop. The proportional increase in pressure drop for turbulent flow is lower than that for laminar flow. The traditional equation for pressure drop fails to accurately estimate the pressure drop for laminar and turbulent flows. Accordingly, this study developed new empirical equations for the friction factor for both laminar and turbulent flows, and the maximum deviations between calculated and experimental results were reduced to within the ranges of-6.17% to 3.55% and -3.08% to 3.81%, respectively, that is, for TiO2/water nanofluid, the correlations apply better to turbulent than to laminar flow.

关键词： Titania (TiO2) Nanofluid Laminar flow Turbulent flow

Dual-frequency whole body vibration enhances vertical jumping and change-of-direction ability in rugby players

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Journal of Sport and Health Science 2017年第3期6卷 346-351页

作者： Wen-Wen Yang Li-Wei Chou Wei-Han Chen Tzyy-Yuang Shiang Chiang Liu Graduate Institute of Sports Equipment technology University ofTaipeiTaipei 111TaiwanChina department of Physical Therapy andAssistive technology National Yang-Ming UniversityTaipei 112TaiwanChina department of Physical Education National Taiwan Normal UniversityTaipei 106TaiwanChina department of Athletic Performance National Taiwan Normal UniversityTaipei 116TaiwanChina

Background:Traditional vertical and side-alternating whole body vibrations(WBV) can effectively improve muscle power performance but have a limited efficacy for enhancing change-of-direction(COD) *** dual-plate WBV uniquely providing various directions of movements with higher and distinctive frequencies for each leg may cause better acute effect on muscle power and stretch-shortening cycle efficacy contributing to COD ***,the purpose of this study was to investigate the acute effect of dual-or single-frequency WBV on squat jumps(SJs),countermovement jumps(CMJs),eccentric utilization ratios(EURs),and COD ability in rugby ***:Fourteen male rugby players were recruited and performed a 4 min partial squat with 3 types of WBV protocols on a dual-plate WBV machine,including 1 dual-frequency WBV protocol(DFW) with the dominant leg receiving 35 Hz and the non-dominant leg receiving 45 Hz,and2 single-frequency WBV protocols(SFWs) with 35 Hz or 45 Hz provided to both legs(SFW35Hz and SFW45Hz) on 3 different ***:The results showed that all the vibration protocols significantly improved SJ and CMJ performances(SJ:p = 0.008;CMJ:p 0.05).In addition,only the DFW significantly improved COD ability(p = 0.001 for the pre–post comparison).Conclusion:A 4 min dual-frequency WBV session improved both vertical jumping and COD ability in rugby players,suggesting that this could be a potential warm-up protocol for athletes.

关键词： Agility Balance Frequency Strength Stretch-shortening cycle Training Warm-up

High temperature slows down growth in tobacco hornworms （Manduca sexta larvae） under food restriction

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Insect Science 2015年第3期22卷 424-430页

作者： Matthew B. Hayes Lihong Jiao Tsu-hsuan Tsao Ian King Michael Jennings Chen Hou department of Biological Science Missouri University of Science and Technology Rolla MO 65409 USA department of Biological Science National Taiwan Normal University TaipeL Taiwan 11677 China

When fed ad libitum （AL）, ectothermic animals usually grow faster and have higher metabolic rate at higher ambient temperature. However, if food supply is limited, there is an energy tradeoff between growth and metabolism. Here we hypothesize that for ectothermic animals under food restriction （FR）, high temperature will lead to a high metabolic rate, but growth will slow down to compensate for the high metabolism. We measure the rates of growth and metabolism of 4 cohorts of5th instar hornworms （Manduca sexta larvae） reared at 2 levels of food supply （AL and FR） and 2 temperatures （20 and 30 ℃）. Our results show that, compared to the cohorts reared at 20 ℃, the ones reared at 30 ℃ have high metabolic rates under both AL and FR conditions, but a high growth rate under AL and a low growth rate under FR, supporting this hypothesis.

关键词： energy budget food restriction growth hornworm metabolism tradeoff

Surface plasmon polariton nanolasers:Coherent light sources for new applications

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Chinese Physics B 2018年第11期27卷 136-146页

作者： Yu-Hsun Chou Chia-Jui Chang Tzy-Rong Lin Tien-Chang Lu Physics department University of Michigan450 Church StreetAnn ArborM1481092-122USA department of Photonics "National"Chiao Tung UniversityHsinchu 300TaiwanChina department of Mechanical and mechatronic Engineering "National"Taiwan Ocean UniversityKeelung 20224TaiwanChina Center of Excellence for Ocean Engineering "National"Taiwan Ocean UniversityKeelung 20224TaiwanChina

The invention of the Internet and mobile devices has caused tremendous changes in human lives over the past two *** technology has broken through limitations of geospatial space,enabling extremely high-speed data transmission and new types of data *** recent years,demands for data processing have shown an increasing ***,data generated from internet-related applications such as cloud services and self-driving technology are likely to grow exponentially over the coming ***,data transmission inside integrated circuits mainly relies on metal ***,the substantial resistive–capacitive delay and energy loss that are caused by metal wires limit data transmission *** interconnection has been regarded as a major solution to efficiently reduce energy consumption and increase data transmission *** size of conventional semiconductor laser devices,which are the key component in optical interconnection,cannot be smaller than the wavelength of light,which is a fundamental physical obstacle to lasers integrating with current electronic integrated circuits in reasonable *** realize optical interconnection,the volume of the laser device must match the existing electronic ***,the use of diffraction-unlimited plasmonic lasers has been successfully demonstrated,and these have great potential in different *** this paper,we discuss the recent progress toward surface plasmon polariton lasers and provide practical insights into the challenges in realizing these novel devices.

关键词： ZnO surface plasmon polariton silver laser