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Numerical Implementation of a Unified Viscoplastic Model for Considering Solder Joint Response under Board-Level Temperature Cycling

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Computer Modeling in Engineering & Sciences 2021年第8期128卷 639-668页

作者： hung-Chun Yang Tz-Cheng Chiu Department of Mechanical Engineering National Cheng Kung UniversityTainan701Taiwan

An implicit integration scheme was developed for simulating the viscoplastic constitutive behavior ofSn3.0Ag0.5Cu solder and programmed into a user material subroutine of the finite element software ANSYS. Thenumerical procedure first solves the essential state variables by using a three-level iterative procedure, and updatesthe remaining stress and state variables accordingly. The numerical implementation was applied to consider theresponses of solder joints in an electronic assembly under temperature cycling condition. The viscoplastic strainenergy density accumulation over one temperature cycle was identified as a feasible parameter for evaluating thethermomechanical reliability of the solder joints.

关键词： Pb-free hysteresis ratcheting fatigue tangent modulus

Salt Tolerance in Soybean

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Journal of Integrative Plant Biology 2008年第10期50卷 1196-1212页

作者： Tsui-hung Phang Hon-Ming Lam Department of Biology The Chinese University of Hong KongShatinHong Kong China State Key Laboratory for Agrobiotechnology The Chinese University of Hong KongShatinHong Kong China

Soybean is an important cash crop and its productivity is significantly hampered by salt stress. High salt imposes negative impacts on growth, nodulation, agronomy traits, seed quality and quantity, and thus reduces the yield of soybean. To cope with salt stress, soybean has developed several tolerance mechanisms, including：（i） maintenance of ion homeostasis; （ii） adjustment in response to osmotic stress; （iii） restoration of osmotic balance; and （iv） other metabolic and structural adaptations. The regulatory network for abiotic stress responses in higher plants has been studied extensively in model plants such as Arabidopsis thaliana. Some homologous components involved in salt stress responses have been identified in soybean. In this review, we tried to integrate the relevant works on soybean and proposes a working model to describe its salt stress responses at the molecular level.

关键词： abiotic stress Glycine max ion homeostasis osmotic adjustment reactive oxygen species scavenging salt tolerance soybean.

CD14 promoter polymorphism in Chinese alcoholic patients with cirrhosis of liver and acute pancreatitis

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World Journal of Gastroenterology 2005年第38期11卷 6043-6048页

作者： Hsin-hung Huang Tsai-Yuan Hsieh Division of Gastroenterology

AIM： To investigate the relationship between genetic polymorphism of the CD14 promoter and the occurrence of alcoholic cirrhosis and alcoholic pancreatitis, and to challenge the conclusion made earlier that the patients with acute alcoholic pancreatitis and patients with alcoholic cirrhosis of liver are two different subpopulations. METHODS： Using the polymerase chain reaction-restriction fragment length polymorphism （PCR-RFLP） method, we determined the polymorphism of CD14 gene and aldehyde dehydrogenase gene 2 （ALDH 2） in 335 alcoholic patients with different organ complications i.e., cirrhosis of liver （n = 100）, acute pancreatitis （n = 100）, esophageal cancer （n = 82） and avascular necrosis of hip joint （AVN）（n = 53） and 194 non-alcoholic controls in a Chinese group. RESULTS： The results showed that the carriage of T allele was not different among alcoholic patients with cirrhosis of liver, alcoholic patients with other complication and non-alcoholic controls. On the other hand, the carriage of the C allele was significantly more prevalent for alcoholic pancreatitis than for esophageal cancer （0.79 vs 0.60, P〈0.001）, alcoholic AVN （0.79 vsO.65, P〈0.025） and nonalcoholic controls （0.79 vs 0.68, P〈0.025）. Furthermore, when only subjects with ALDH2 1-1 genotype were examined, the C allele frequency was significantly more prevalent for alcoholic pancreatitis than for alcoholic liver cirrhosis （0.82 vs 0.69, P〈0.025）, esophageal cancer （0.82 vs 0.61, P〈0.01）, alcoholic AVN （0.82 vs 0.64, P〈0.01） and non-alcoholic controls （0.82 vs0.69, P〈0.05）. CONCLUSION： The C allele may be associated with some mechanism, which is important in the pathogenesis of alcoholic pancreatitis, and that alcoholic patients with acute pancreatitis and cirrhosis of liver are probably two different subpopulations.

关键词： CD14 promoter Polymorphism Alcoholic patients

Numerical Simulation of Bragg Reflection Based on Linear Waves Propagation over A Series of Rectangular Seabed

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China Ocean Engineering 2008年第1期22卷 71-86页

作者： Chih-Chung WEN Li-hung TSAI Department of Environmental Engineering Hungkuang University Center of Harbor and Marine Technology Institute of TransportationMinistry of Transportation and Communications

A numerical model, Evolution Equation of Mild-Slope Equation （EEMSE） developed by Hsu et al. （2003）, was applied to study the Bragg reflection of water waves over a series of rectangular seabed. Three key parameters of the Bragg reflection including the peak coefficient of primary Bragg reflection, its corresponding relative wavelength, and the bandwidth, have shown to be effective in describing the characteristics of the primary Bragg reflection. The characteristics of the Bragg reflection were investigated under the various conditions comprising number, height, and spacing interval of a series of rectangular seabed. The results reveal that the peak of Bragg reflection increases with the increase of rectangular seabed height and number, the bandwidth and the shift value of the Bragg reflection depend on the increase of the rectangular seabed height as well as the decrease of rectangular seabed number, and the relative rectangular seabed spacing in the rang of 3 and 4 could produce higher Bragg reflection. Finally, a correlative and regressive analysis is performed by use of the calculated data. Based on the results of the analysis, empirical equations were established. Our study results can provide an appropriate choice of a series of rectangular seabed field for a practical design.

关键词： Bragg reflection mild-slope equation rectangular seabed bandwidth of the Bragg reflection rapidly varying component

Hydraulic resistance of river ice jams

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Journal of Hydrodynamics 2019年第3期31卷 504-511页

作者： Lin Fan Ze-yu Mao hung Tao Shen Department of Hydraulic Engineering Tsinghua University Beijing 100084 China Development Research Center of the Ministry of Water Resources Beijing 100036 China Department of Civil and Environmental Engineering Clarkson University Potsdam NY 13676 USA

The hydraulic resistance of the river ice jams consists of the resistances due to the seepage flow through the jam and the shear stress on the undersurface of the jam. Existing empirical formulations consider only the the undersurface resistance of the jam, and come up with relations between the jam resistance and the jam thickness with very slight theoretical basis. Based on the analysis of the seepage flow resistance and the flow resistance of the undersurface of the jam, it is shown that the resistance due to the seepage flow is a dominating part of the jam resistance, except for the portion of the jam where the thickness is very small. This analysis also shows that the total jam resistance can be approximated by a linear function of the jam thickness or the ratio of the jam thickness to the flow depth under the jam.

关键词： River ice hydraulic resistance ice jam friction factor Manning's coefficient

Analysis of ground vibrations due to underground trains by 2.5D finite/infinite element approach

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Earthquake Engineering and Engineering Vibration 2010年第3期9卷 327-335页

作者： Hsiao-Hui hung Y. B. Yang Center for Research on Earthquake Engineering （NCREE） Taipei 10617 Chinese Taipei Yunlin University of Science and Technology Douliu Yunlin 64002 Chinese Taipei

The 2.5D finite/infinite element approach is adopted to study wave propagation problems caused by underground moving trains. The irregularities of the near field, including the tunnel structure and parts of the soil, are modeled by the finite elements, and the wave propagation properties of the far field extending to infinity are modeled by the infinite elements. One particular feature of the 2.5D approach is that it enables the computation of the three-dimensional response of the half-space, taking into account the load-moving effect, using only a two-dimensional profile. Although the 2.5D finite/infinite element approach shows a great advantage in studying the wave propagation caused by moving trains, attention should be given to the calculation aspects, such as the rules for mesh establishment, in order to avoid producing inaccurate or erroneous results. In this paper, some essential points for consideration in analysis are highlighted, along with techniques to enhance the speed of the calculations. All these observations should prove useful in making the 2.5D finite/infinite element approach an effective one.

关键词： ground vibrations 2.5D finite/infinite element underground train wave number wave propagation

Effects of sediment on the dynamic pressure of water and sediment on dams

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Chinese Science Bulletin 2001年第6期46卷 521-524页

作者： J.K.hung China Institute of Water Resources and Hydropower Research Beijing China University of Pittsburgh USA

After a reservoir has been in operation for a period of time, a sediment layer is likely formed before the dam. Since studies of the effects of sediment layers on the hydrodynamic pressures of impounded water and the aseis-mic responses of dam are few, the dynamic effect of sediment may be applied neither in the seismic design of new dams nor in the assessment of earthquake safety of existing dams. However, a common practice of the action of sediment layers and foundation is based on a partial energy absorption boundary. It is shown that during a vertical harmonic ground motion, the sediment layer could alter the natural frequencies of reservoir. The dynamic pressure on a rigid vertical dam face caused by the vertical ground motion is obtained through a computational model and an experimental test by using a shaking table. With a change in the thickness of sediment, the frequency corresponding to the inertia amplification effect appears to vary gradually. The results are useful for further study of

关键词： dam earthquake hydrodynamic pressure sediment.

EZ-Manipulator:Designing a mobile,fast,and ambiguity-free 3D manipulation interface using smartphones

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Computational Visual Media 2018年第2期4卷 139-147页

作者： Po-Huan Wseng Shih-Hsuan hung Pei-Ying Chiang Chih-Yuan Yao hung-Kuo Chu "National Tsing Hua University" Hsinchu 30013TaiwanChina. "National Taiwan University of Science and Technology" Taipei 10607TaiwanChina. "National Taipei University of Technology" Taipei 10607TaiwanChina.

Interacting with digital contents in 3 D is an essential task in various applications such as modeling packages, gaming, virtual reality, etc. Traditional interfaces using keyboard and mouse or trackball usually require a non-trivial amount of working space as well as a learning process. We present the design of EZ-Manipulator, a new 3 D manipulation interface using smartphones that supports mobile, fast, and ambiguity-free interaction with 3 D objects. Our system leverages the built-in multi-touch input and gyroscope sensor of smartphones to achieve 9 degrees-of-freedom axis-constrained manipulation and free-form *** EZ-Manipulator to manipulate objects in 3 D is easy. The user merely has to perform intuitive singleor two-finger gestures and rotate the hand-held device to perform manipulations at fine-grained and coarse levels respectively. We further investigate the ambiguity in manipulation introduced by indirect manipulations using a multi-touch interface, and propose a dynamic virtual camera adjustment to effectively resolve the ambiguity. A preliminary study shows that our system has significant lower task completion time compared to conventional use of a keyboard–mouse interface, and provides a positive user experience to both novices and experts.

关键词： 3D manipulation interface interaction technique multi-touch gyroscope sensorl mobile device input device

Grain size altering yielding mechanisms in ultrafine grained high-Mn austenitic steel:Advanced TEM investigations

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Journal of Materials Science & Technology 2021年第27期86卷 192-203页

作者： Chang-Yu hung Yu Bai Nobuhiro Tsuji Mitsuhiro Murayama Department of Materials Science and Engineering Virginia TechBlacksburgVA24061USA Department of Materials Science and Engineering Kyoto UniversityYoshida-honmachiSakyo-kuKyoto606-8501Japan Elements Strategy Initiative for Structural Materials Kyoto UniversityYoshida-honmachiSakyo-kuKyoto606-8501Japan Institute for Materials Chemistry and Engineering Kyushu UniversityKasugaFukuoka8168580Japan

The underlying mechanism of discontinuous yielding behavior in an ultrafine-grained(UFG)Fe-31 Mn-3 Al-3 Si(wt.%)austenitic TWIP steel was investigated by the use of advanced TEM technique with taking the plastic deformation mechanisms and their correlation with grains size near the macroscopic yield point into *** yield drop mechanisms such as the dislocation locking by the Cottrell atmosphere due to the presence of interstitial impurities cannot explain the origin of this phenomenon in the UFG high-Mn austenitic TWIP ***,we experimentally revealed that the plastic deformation mechanisms in the early stage of deformation,around the macroscopic yield point,show an obvious association with grain *** specifically,the main mechanism shifts from the conventional slip in grain interior to twinning nucleated from grain boundaries with decreasing the grain size down to less than 1μ*** observation indicates that the grain size dependent deformation mechanisms transition is also deeply associated with the discontinuous yielding behavior as it could govern the changes in the grain interior dislocation density of mobile dislocations around the macroscopic yield point.

关键词： Ultrafine grains TWIP steel Yield-drop phenomenon Deformation twin nucleation Structural defects Transmission electron microscopy