http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Ying, Alice,Zhang, Hongjie,Merrill, Brad,Ahn, Mu-Young,Cho, Seungyon Elsevier 2018 Fusion engineering and design Vol.136 No.2
<P><B>Abstract</B></P> <P>An integrated, multi-physics, dynamic predictive tool to quantify tritium retention, removal, and permeation for HCCR Test Blanket System (TBS) is presented in this paper. The tool expands from detailed COMSOL component models developed previously at UCLA, into an integrated, system-level blanket model using MATLAB/Simulink. It aims at achieving self-consistent predictions in particular concerning dynamic tritium concentration built-up in the He coolant. The integration is achieved by implementing COMSOL component models in the discrete section of Simulink S-Functions. The model replicates HCCR TBS process flow diagram and preserves main tritium flow characteristics for both helium cooling and tritium extraction systems. Current results demonstrate importance of detailed component models as well as dynamic simulation for improved accuracy on answers to questions related to safety/licensing and designs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A dynamic tritium transport modeling is developed by constructing COMSOL models in Simulink environment to achieve system-level integration. </LI> <LI> Time and spatial dependent temperatures performed for the detailed component model to study tritium transport behavior including permeation. </LI> <LI> Isotope effect due to the addition of H<SUB>2</SUB> in the purge gas has been taken into account in the estimation of tritium permeation. </LI> <LI> Ion implantation to the FW was simulated in calculating accumulated tritium partial pressure built-up in the He coolant. </LI> </UL> </P>
Grab overtaking Uber: The David versus Goliath of Ride-Hailing App in Southeast Asia
Alice Tsz Ling Tam,Alison Wai Ting Lam,Katrina Ngai Han Chiu,Leona Ying Tong Chen,Haipeng Shen,Wei Zhang Academy of Asian Business (AAB) 2018 Academy of Asian Business Review Vol.4 No.2
This case study on Grab, a locally founded ride-hailing startup in ASEAN, traces its development from its humble start to its victory of ousting Uber in 2018. This case study uncovers the elements that contributed to Grab’s success, providing inspiration on how Asian companies can possibly prevail over the more established Western counterparts despite of great adversity. The report compares the development of both Grab and Uber, followed by a discussion of turning points on how Grab played out the battle with Uber across several ASEAN countries without central jurisdiction to favor it. Factors behind the success of Grab for each turning point are closely examined. Potential difficulties faced by Grab and recommendations to solve the problems are also identified. Grab manifests the spirit of “think global and act local” to succeed in the sharing economy by putting feet on the ground and resolving real “pain points” for consumers. While there are increasing number of companies with a sharing economy business model, the conventional approach of offering a low price to customers and a high pay to employees may not guarantee success for a business anymore. This case study of Grab aims to provide insights for these enterprises to conquer the market in the competitive modern business world.
Modifying Young's modulus in DEM simulations based on distributions of experimental measurements
Van Lew, Jon T.,Park, Yi-Hyun,Ying, Alice,Abdou, Mohamed Elsevier 2015 Fusion engineering and design Vol.98 No.-
<P><B>Abstract</B></P> <P>The discrete element method, as currently employed by members of the fusion community, is rooted on the assumption that each pebble is a perfectly elastic material that obeys Hertz's theory for normal interaction. This assumption impacts the magnitude of inter-particle forces predicted by the models. We scrutinize the Hertzian assumption with single-pebble crush experiments with carefully recorded force-displacement responses and compare them to the non-linear forces predicted by a Hertzian pebble with bulk properties reported in literature. We found each pebble generally has a non-linear force response but with varying levels of stiffness that qualitatively matched the curves from Hertz theory. Assuming Hertzian interaction, we backed-out an elastic modulus for each pebble. We define a softening coefficient, <I>κ</I>, as the ratio of the pebble's elastic modulus to the sintered bulk value from literature. After determining the <I>κ</I> value for every pebble in our batch, we discovered a probability distribution for different batches. The distribution is attributed to the varying micro-structure of each pebble. We incorporate the results into our DEM algorithms, distributing <I>κ</I> values at random to pebbles satisfying the probability curves of experiments. DEM simulations of pebble beds in oedometric compression are carried out to determine macroscopic responses of stress–strain, contact force distributions at maximum stress, and a prediction of pebbles crushing at that point. In all cases studied here, the pebble beds with modified Young's modulus had smaller overall contact forces and fewer predicted crushed pebbles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Developing a modification to the Young's modulus of individual pebbles based on variations seen in single pebble crushing experiments. </LI> <LI> Developing an equation to translate between single pebble crush data to a “force value” that can be applied to individual pebbles in DEM simulations. </LI> <LI> Applying the above developments into DEM simulations on uniaxial compression tests, with parametric variations on pebble diameter distribution and pebble coefficient of friction. </LI> <LI> Found that modified Young's modulus simulations resulted in pebbles that predicted fewer broken pebbles than the older, single value Young's modulus version of DEM models. </LI> </UL> </P>
Hydrogen adsorption performance for large-scale cryogenic molecular sieve bed
Park, Soon Chang,Son, Seok-Kwon,Ahn, Mu-Young,Ying, Alice,Cho, Seungyon,Park, Yi-Hyun,Lee, Youngmin Elsevier 2019 Fusion engineering and design Vol.146 No.2
<P><B>Abstract</B></P> <P>Cryogenic hydrogen adsorption using molecular sieve beds is considered to be one of the main candidate processes for recovery of produced tritium from purge gas in breeding blankets and it has been chosen for separating hydrogen isotopes in Tritium Extraction System (TES) of Korean Helium Cooled Ceramic Reflector (HCCR) Test Blanket System (TBS). Various adsorbents and their performance have been studied for the cryogenic adsorption using small-scale experiments. However, large-scale experiments comparable to TBS-relevant scale are required to have sufficient confidence for component design and performance prediction of Cryogenic Molecular Sieve Bed (CMSB) for the TBS and beyond. To properly evaluate hydrogen adsorption performance of a large size CMSB, a series of experiments have been performed using PGLoop facility which is constructed and operated in the National Fusion Research Institute. The experimental conditions were set to include breeding-blankets-relevant parameters. As such, the effects of swamping ratio, total pressure, and flow rates on the performances of CMSB were studied in the range of hydrogen partial pressures from 100 to 700 Pa. While a slight reduction in hydrogen adsorption performance is observed in comparison to the small isotherm experiments, which can be attributed to scale-up effects, it shows that the experimental results agree reasonably well with existing literature data.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Large-scale hydrogen adsorption experiments were conducted using Cryogenic Molecular Sieve Bed module of PGLoop facility. </LI> <LI> The experimental parameters were chosen considering blanket conditions. </LI> <LI> The size effect was not large, and the experimental results agree reasonably well with existing small-scale data. </LI> <LI> The diffusion of hydrogen gas in the purge gas is the dominating factor in CMSB design. </LI> </UL> </P>