The Immersed Boundary Method for Two-Dimensional Foam with Topological Changes

Kim, Yongsam,Seol, Yunchang,Lai, Ming-Chih,Peskin, Charles S. Global Science Press 2012 Communications in computational physics Vol.12 No.2

<B>Abstract</B><P>We extend the immersed boundary (IB) method to simulate the dynamics of a 2D dry foam by including the topological changes of the bubble network. In the article [Y. Kim, M.-C. Lai, and C. S. Peskin, J. Comput. Phys. 229:5194-5207,2010], we implemented an IB method for the foam problem in the two-dimensional case, and tested it by verifying the von Neumann relation which governs the coarsening of a two-dimensional dry foam. However, the method implemented in that article had an important limitation; we did not allow for the resolution of quadruple or higher order junctions into triple junctions. A total shrinkage of a bubble with more than four edges generates a quadruple or higher order junction. In reality, a higher order junction is unstable and resolves itself into triple junctions. We here extend the methodology previously introduced by allowing topological changes, and we illustrate the significance of such topological changes by comparing the behaviors of foams in which topological changes are allowed to those in which they are not.</P>

Simulation of Axisymmetric Scramjet Combustion Flowfields Using Weno Navier-Stokes Solvers

Jaw-Yen Yang,J.C. Huang,Y S. Lai,C. S. Kuo 한국전산유체공학회 2014 한국전산유체공학회 학술대회논문집 Vol.2014 No.10

This study is based on the theory of gas dynamics and uses the Navier-Stokes equations as the governing equations to solve the fluid flow field problems of the scramjet. For the turbulent flow, we use the simple Spalart-Allmaras one equation turbulence model (S-A model) which produces better results for near wall and boundary layer flow field problems. The lower-upper symmetric Gauss-Seidel (LU-SGS) implicit scheme, whose results converge efficiently under steady state conditions, is combined with the Weighted Essentially Non-Oscillatory (WENO) scheme to construct a numerical model of the scramjet. Using the WENO scheme’s high-order accuracy and its non-oscillatory solution at discontinuous areas, we can solve supersonic flow field problems with multiple shock wave interactions. This simulation procedure is verified against two partial examples from literature to ensure its accuracy, and is then applied to a complete geometric model of a scramjet with different initial conditions for a full flow field analysis. The Mach number, density, static temperature and pressure are found and the results discussed. It is found that even when the shock waves are very close to each other, the WENO scheme produces better simulation results than other numerical approaches.

Nine facultative endosymbionts in aphids. A review

Jianqing Guo,Séverin Hatta,Kang-lai He,Julian Chen,Frédéric Francis,Zhen-ying Wang 한국응용곤충학회 2017 Journal of Asia-Pacific Entomology Vol.20 No.3

Aphids are frequently engaged in mutualistic associations with endosymbionts. Symbionts are bacterial or fungal microorganisms that can be obligate or facultative to aphids. Research showed facultative (or secondary) symbionts have numerous effects on their host aphids such as resistance to heat shock, parasitoids and fungus etc., which may consequently promote a co-evolution between symbionts and hosts. However, this symbiotic relation may be affected by several factors, such as the ability of symbionts to spread from aphids to others within and across populations, and the cost of infections for hosts. Moreover, aphid-symbionts interactions may be affected by aphid living environment such as its host plant, the presence of natural enemies or the temperature. Here we firstly described the functions of nine facultative symbionts (Serratia symbiotica, Hamiltonella defensa, Regiella insecticola, Rickettsia, Rickettsiella, PAXS (pea aphid X-type symbiont), Spiroplasma, Wolbachia and Arsenophonus) studied in aphids one by one, and discussed the associations between these symbionts and aphids, plants and environment. We aim to have a better knowledge of the roles the facultative symbionts play in aphid biology, ecology and evolution, which we believe can provide new inspirations for aphid control.

Effects of Dietary Energy Density on Growth, Carcass Quality and mRNA Expression of Fatty Acid Synthase and Hormone-sensitive Lipase in Finishing Pigs

Liu, Z.H.,Yang, F.Y.,Kong, L.J.,Lai, C.H.,Piao, X.S.,Gu, Y.H.,Ou, X.Q. Asian Australasian Association of Animal Productio 2007 Animal Bioscience Vol.20 No.10

A single factorial experiment was conducted to test the effects of three dietary levels of energy on mRNA expression of fatty acid synthase (FAS-mRNA) and hormone-sensitive lipase (HSL-mRNA) and their association with intramuscular fat in finishing pigs. 72 crossbred (Large $White{\times}Rongchang$) barrows with an average initial body weight of 20.71 (s.e. 0.1) kg, were randomly allotted to three dietary treatments (11.75, 13.05 and 14.36 MJ DE/kg) and fed until slaughtered at 100 or 101 kg. The diets were iso-nitrogenous and iso-essential amino acids. The growth performances including the duration of finishing were changed linearly (p<0.05) or quadratically (p<0.05) with increased dietary energy levels. The effects of dietary energy content on the percentage of external fat, intramuscular backfat and the fat thickness were linear (p<0.05). The content of dietary energy increased FAS-mRNA linearly or quadratically, while HSL-mRNA decreased linearly or quadratically in backfat and Longissmus dorsi muscle. Meanwhile, significant positive correlations (p<0.05) were found between energy level and intramuscular fat, FAS-mRNA or the ratio of FAS-mRNA to HSL-mRNA, between the ratio of FAS-mRNA to HSL-mRNA and intramuscular fat. However, the correlations between HSL mRNA and dietary energy or intramuscular fat were negative (p<0.05). The results indicated that dietary energy level regulates lipid accumulation, especially intramuscular fat, possibly by modulating the mRNA of FAS and HSL together rather than individually.

E-Entrepreneurial intention among young Chinese adults

Lai Linda S.L.,To Wai Ming 기술경영경제학회 2020 ASIAN JOURNAL OF TECHNOLOGY INNOVATION Vol.28 No.1

E-entrepreneurship plays a key role in China’s economic development because it encourages new business ventures and innovation. Hence, understanding what motivates young Chinese people to engage in e-entrepreneurship is an important issue for regional and global development. This study proposed entrepreneurship policy and entrepreneurship education as key antecedents of people’s attitude towards e-entrepreneurship, subjective norms, and perceived behaviour control, which in turn influenced their intention to start an e-business. The proposed model was tested using the responses from 220 young Chinese adults. The results of structural equation modelling confirmed that entrepreneurship policy and e-entrepreneurship education were antecedents of people’s attitude towards e-entrepreneurship, subjective norms, and perceived behaviour control, while subjective norms and perceived behaviour control significantly influenced their e-entrepreneurial intention. Nevertheless, people’s attitude towards e-entrepreneurship did not have a significant influence on their e-entrepreneurial intention. The study findings were discussed with respect to the critical e-business trend in China that shapes young entrepreneurs and their creative goals.

Study on the estimation of high temperature fracture parameter for mismatched weld creep cracks

Lai, H.S.,Yoon, K.B. Pergamon Press 2016 Engineering fracture mechanics Vol.163 No.-

<P>Evaluation of the creep crack growth is very important for predicting the life of high temperature structures. Since C-t can uniquely characterize creep crack growth from the small scale creep stage to the extensive steady state creep stage, an engineering estimation method of C-t was proposed for a crack located in the weld with mismatched material properties between the base material and the weld material based on the simulation results of compact tension specimens. For the crack located in the center of welding seam, C-t was estimated by the proposed method under the small scale creep stage and by the reference stress method under the extensive steady state creep stage; in this way, C-t was estimated under the whole creep stage. The estimated results agreed well with the simulation results if the width of welding seam of h was no smaller than the size of the stress intensity factor dominance zone. (C) 2016 Elsevier Ltd. All rights reserved.</P>

STATISTICAL STUDIES OF THE SOLAR $\gamma$-RAY FLARES

LAI S. P.,CHIUEH T. The Korean Astronomical Society 1996 Journal of The Korean Astronomical Society Vol.29 No.suppl1

Development of a Child Detection System with Artifcial Intelligence Using Object Detection Method

S. N. David Chua,S. F. Lim,S. N. Lai,T. K. Chang 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.6

The issue of children dying due to vehicular heatstroke has raised signifcant concerns of public interest. The advancement of artifcial intelligence (AI) technology, particularly in image classifcation and object detection, could be applied to overcome the current faws of the vehicular occupant detection devices that often failed to serve as a triggering system to caretakers. In this paper, a technique for child detection with transfer learning is proposed. A real-time child detection system that consisted of a camera as an input medium, a classifer to detect the presence of a child and a triggering system in audio and visual forms was established. The modern convolutional object detector, SSD Mobilenet v1 was trained with Microsoft Common Objects in Context (MS COCO) dataset as a starting point of the training process. The model was then assessed and retrained to possess the ability to classify human into an adult or a child. The accuracy of the model was measured by counting the percentage of pixels labelled correctly per class. Based on the mean Average Precision (mAP), the detection system achieved an overall precision of 0.969 and the experimental results obtained showed a precision of 0.883, giving an error of less than ten percent.

Mechanical property enhancement of ultra-thin PBI membrane by electron beam irradiation for PEM fuel cell

Lai, S.,Park, J.,Cho, S.,Tsai, M.,Lim, H.,Chen, K. Pergamon Press ; Elsevier Science Ltd 2016 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.41 No.22

<P>The ultra-thin cross-linked PBI membrane containing phosphoric acid (PA) for possible use in a fuel cell was prepared by electron beam irradiation method. The preparation procedure involved two steps: (a) irradiation of PBI membranes (PBI-1, PBI-2 and PBI-3) by an electron beam with increased dose energy and (b) doping the irradiated membranes with PA. These membranes were characterized in terms of mechanical properties, chemical and thermal stability were evaluated using Universal Testing machine, Ultraviolet visible spectroscopy and thermogravimetric analysis, respectively. Compared to the pristine PBI membrane of thickness 20 gm, the cross-linked PBI membranes show much better mechanical properties and improved chemical and thermal stability. In addition, the tensile strength of the cross-linked PBI membranes with PA ranges from 19 MPa to 27 MPa, which is higher than that of the pristine PBI membrane with PA (14 MPa). Besides these, the fuel cell performance of the PBI-1 is similar to that of the pristine PBI membrane of thickness 20 gm, but higher than common used PBI membrane of thickness 40 gm. The overall results suggest that the membrane has a great potential for possible application in high temperature PEM fuel cell. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.</P>

Effects of Replacing Spray Dried Porcine Plasma with Solpro500 on Performance, Nutrient Digestibility and Intestinal Morphology of Starter Pigs

Lai, C.H.,Qiao, S.Y.,Li, Defa,Piao, X.S.,Bai, L.,Mao, X.F. Asian Australasian Association of Animal Productio 2004 Animal Bioscience Vol.17 No.2

The objective of this study was to evaluate Solpro500 (a wheat hydrolysate containing a high level of glutamine) as a replacement for spray dried porcine plasma (SDPP) in diets fed to nursery pigs. One hundred and eight pigs (Dalland, $5.39{\pm}0.80$ kg BW) weaned at 21 days were assigned to one of three treatment groups for a 28 day feeding trial. The experimental diets were based on corn and soybean meal and were supplemented with either 8% SDPP, 4% SDPP plus 4% Solpro500 or 8% Solpro500. Each treatment was fed to six pens with six pigs per pen (4 barrows and 2 gilts). The experimental results indicated no significant difference (p>0.05) in daily gain, feed intake or feed efficiency for pigs fed the three experimental diets. However, the diarrhea index for pigs fed either 4% SDPP and 4% Solpro500 or 8% Solpro500 was lower (p<0.05) than that for pigs fed 8% SDPP. No differences (p>0.05) were found in the apparent fecal digestibility of dry matter, organic matter or crude protein between pigs fed the three diets. The intestinal morphology (villous height, villous width and crypt depth) was not affected by diet treatments (p>0.05). In conclusion, Solpro500 SDPP can replace SDPP without any negative effects on nursery pig performance.