| 1. |
- Andersson, M., et al.
(author)
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Coupling of lattice boltzmann and volume of fluid approaches to study the droplet behavior at the gas diffusion layer/gas channel interface
- 2018. - 13
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In: ECS Transactions. - : The Electrochemical Society. - 1938-6737 .- 1938-5862. - 9781607688600 ; 86, s. 329-336
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Conference paper (peer-reviewed)abstract
- A typical polymer electrolyte fuel cell (PEFC) flow field consists of micro/minichannels. The continues removal of liquid water from the cathode channels is a critical topic, as water droplets forming in the channels may block the transport of gaseous oxygen to the active sites, which not only gives an uneven current distribution and substantial loss of performance, but also, increases degradation rates and unstable operation. Water generated by the electrochemical reactions condenses, depending on temperature mainly, into liquid form, potentially flooding various part of the PEFC. The aim of this work is to obtain an increased understanding of the droplet behavior at the gas diffusion layer (GDL) interface with the gas channels in PEFCs by the coupling of Lattice Boltzmann (LB) and Volume of Fluid (VOF) approaches. A multiscale environment is established with input parameters in the VOF model being extracted from in-house LB calculations. It is clear that the contact angle as well as the size of the liquid droplet vary with positions at the GDL surface, depending on the stochastic GDL geometry. A VOF model describing one straight channel with one gas inlet, one liquid inlet (at the GDL surface) and one two-phase outlet is employed.
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| 2. |
- Beale, S. B., et al.
(author)
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Combined two-phase co-flow and counter-flow in a gas channel/porous transport layer assembly
- 2020. - 9
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In: PRiME 2020 : Polymer Electrolyte Fuel Cells and Electrolyzers 20 (PEFC and E 20) - Polymer Electrolyte Fuel Cells and Electrolyzers 20 (PEFC and E 20). - : The Electrochemical Society. - 1938-5862 .- 1938-6737. - 9781607685395 ; 98:9, s. 305-315
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Conference paper (peer-reviewed)abstract
- This paper considers a detailed numerical analysis of combined liquid-gas co-flow in a gas channel, with liquid-gas counter-flow in a porous transport layer, as is typically found on the cathode side of a polymer electrolyte fuel cell. The geometry is obtained by digital reconstruction of nano-computer tomography images. From this, the domain is tessellated with an unstructured castellated or octree mesh, upon which the equations of mass and momentum are solved by means of a volume of fluid method. Liquid water is produced from an electrode where gaseous oxygen is simultaneously consumed by electrochemical reduction; Liquid-gas counter flow in the porous transport layer results in liquid drops being entrained in co-flow in the gas channels and convected by the gas downstream.
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| 3. |
- Zhang, Shidong, et al.
(author)
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Simple and complex polymer electrolyte fuel cell stack models : A comparison
- 2018. - 13
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In: ECS Transactions. - : The Electrochemical Society. - 1938-6737 .- 1938-5862. - 9781607685395 ; 86, s. 287-300
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Conference paper (peer-reviewed)abstract
- In this paper, two distinct polymer electrolyte fuel cell stack models are constructed: a detailed numerical model (DNM) employing a fine-scale computational mesh and a coarse-mesh approach based on a distributed resistance analogy (DRA) where diffusion terms in the transport equations are replaced by rate terms. Both methods are applied to a 5-cell, high-temperature polymer electrolyte fuel cell stack with an active area of 200 cm2 per cell. The polarization curve and local current density distributions from both the DRA and DNM are compared with experimental data, finding good agreement. Temperature, pressure, Nernst potential, and species distributions are also exhibited. The DNM displays details of fine-scale local extrema not captured by the DRA; however, the latter requires orders of magnitude less computer processor power and memory for execution. Both methods provide much finer-scale results than present experimental techniques.
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| 4. |
- Iyer, Nirmal, et al.
(author)
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The design and performance of the XL-Calibur anticoincidence shield
- 2023
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In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 1048
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Journal article (peer-reviewed)abstract
- The XL-Calibur balloon-borne hard X-ray polarimetry mission comprises a Compton-scattering polarimeter placed at the focal point of an X-ray mirror. The polarimeter is housed within a BGO anticoincidence shield, which is needed to mitigate the considerable background radiation present at the observation altitude of -40 km. This paper details the design, construction and testing of the anticoincidence shield, as well as the performance measured during the week-long maiden flight from Esrange Space Centre to the Canadian Northwest Territories in July 2022. The in-flight performance of the shield followed design expectations, with a veto threshold <100 keV and a measured background rate of -0.5 Hz (20-40 keV). This is compatible with the scientific goals of the mission, where %-level minimum detectable polarisation is sought for a Hz-level source rate.
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| 5. |
- Abe, K., et al.
(author)
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Font creation using class discriminative deep convolutional generative adversarial networks
- 2018
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In: Proceedings - 4th Asian Conference on Pattern Recognition, ACPR 2017. - : Institute of Electrical and Electronics Engineers Inc.. ; , s. 238-243
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Conference paper (peer-reviewed)abstract
- In this research, we attempt to generate fonts automatically using a modification of a Deep Convolutional Generative Adversarial Network (DCGAN) by introducing class consideration. DCGANs are the application of generative adversarial networks (GAN) which make use of convolutional and deconvolutional layers to generate data through adversarial detection. The conventional GAN is comprised of two neural networks that work in series. Specifically, it approaches an unsupervised method of data generation with the use of a generative network whose output is fed into a second discriminative network. While DCGANs have been successful on natural images, we show its limited ability on font generation due to the high variation of fonts combined with the need of rigid structures of characters. We propose a class discriminative DCGAN which uses a classification network to work alongside the discriminative network to refine the generative network. This results of our experiment shows a dramatic improvement over the conventional DCGAN.
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| 6. |
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| 7. |
- Inai, K., et al.
(author)
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Selective concealment of characters for privacy protection
- 2014
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In: Proceedings - International Conference on Pattern Recognition. - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 333-338
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Conference paper (peer-reviewed)abstract
- A method of concealing characters is proposed for degrading legibility of privacy sensitive textual information in natural scene, such as car license plate numbers and name tags. An important property of the proposed method is that it realizes selective concealing of characters, that is, the proposed method degrades legibility of character regions without degrading the quality of non-character regions. This selective concealment is realized because characters have special concealment characteristics. Specifically, character legibility can be degraded by damaging stroke structure by using exemplar-based image in painting, which does not affect non-character regions. Experimental results of qualitative and quantitative evaluations have proven that the selective concealment is practically possible. Furthermore, the quantitative evaluation through a subjective experiment revealed appropriate setups of image in painting for maximizing selective concealment performance.
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