Article
Thermodynamics
Andreas Kopf, Valerio Frattina, Michele Bardi, Torsten Endres, Gilles Bruneaux, Christof Schulz
Summary: This study presents a two-dimensional thermographic particle image velocimetry (T-PIV) technique for in situ measurement in optically accessible internal combustion (IC) engines. The technique combines temperature and velocity measurements using thermographic phosphor particles as tracers for PIV. The best-suited phosphor material for in-cylinder measurements was identified, and calibration data was generated for signal quantification. The T-PIV technique was successfully applied to obtain instantaneous two-dimensional velocity and temperature fields in the IC engine. However, the technique suffers from low signal intensities at high temperatures, leading to reduced accuracy.
INTERNATIONAL JOURNAL OF ENGINE RESEARCH
(2023)
Article
Materials Science, Characterization & Testing
Elizabeth M. C. Jones, Amanda R. Jones, Caroline Winters
Summary: This study introduces a new diagnostic method, TP + DIC, which combines thermographic phosphors with stereo digital image correlation to measure full-field surface strains and temperatures simultaneously. The method corrects for camera detector nonlinearities and generates pixel-wise calibration curves. TP + DIC is successfully applied to characterize the thermo-mechanical response of stainless steel under tensile testing, and results agree favorably with the more established IR + DIC method.
Article
Engineering, Electrical & Electronic
Honey Nikam, Siddharth Satyam, Shubham Sahay
Summary: In this study, we propose an area- and energy-efficient LSTM network implementation using passive RRAM crossbar arrays, which can be applied to time-series data-dependent applications on IoT edge devices. Through hardware-aware simulation and analysis considering non-ideal hardware artifacts, we demonstrate that this implementation surpasses previous approaches in terms of performance and exhibits robustness against spatial and temporal variations and noise. This work may encourage the experimental realization of LSTM networks on passive RRAM crossbar arrays.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Computer Science, Artificial Intelligence
Mikel Ferrero-Jaurrieta, Zdenko Takac, Javier Fernandez, Lubomira Horanska, Gracaliz Pereira Dimuro, Susana Montes, Irene Diaz, Humberto Bustince
Summary: In this article, the authors generalize the Choquet integral to handle vector inputs and combine it with LSTM to create the VCI-LSTM architecture, which is then applied to sequential image classification and text classification problems.
IEEE TRANSACTIONS ON FUZZY SYSTEMS
(2023)
Article
Mathematics, Interdisciplinary Applications
K. E. ArunKumar, Dinesh Kalaga, Ch Mohan Sai Kumar, Masahiro Kawaji, Timothy M. Brenza
Summary: Since the outbreak in Wuhan, COVID-19 has rapidly spread worldwide, resulting in over 41.39 million confirmed cases and over 1.13 million deaths. Utilizing deep learning models to predict the future transmission trends of COVID-19 can help countries better prepare and control the pandemic.
CHAOS SOLITONS & FRACTALS
(2021)
Article
Engineering, Multidisciplinary
Sunyoung Im, Jonggeon Lee, Maenghyo Cho
Summary: This study proposes a practical framework for surrogate modeling of large-scale elasto-plastic FE models by combining LSTM neural networks and POD. By reducing high-dimensional data and introducing neural network architectures, accurate and robust predictions can be achieved.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2021)
Article
Engineering, Multidisciplinary
K. E. ArunKumar, Dinesh Kalaga, Ch. Mohan Sai M. Kumar, Masahiro Kawaji, Timothy M. Brenza
Summary: This article presents a comparative time-series analysis of deep learning and statistical models for forecasting COVID-19. The study shows that deep learning models such as LSTM and GRU generally outperform statistical models like ARIMA and SARIMA in predicting the cumulative confirmed, recovered, and deaths for most countries. However, some countries may benefit more from statistical models. The study also highlights the importance of factors such as age, preventive measures, and healthcare facilities in the rapid spread of the COVID-19 pandemic.
ALEXANDRIA ENGINEERING JOURNAL
(2022)
Article
Electrochemistry
Sobin Mathew, Elham Hosseinirad, Kyung Chun Kim, Won Sub Chung, Oi Lun Li, Young-Rae Cho
Summary: Novel ceria-based electrocatalysts, Gd-doped CeO2 nanocrystals (GDC) and Sm-doped CeO2 nanospheres (SDC), exhibit excellent activity in oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) with promising stability. The diverse-valence Ce3+/Ce4+ redox states, positive entropy contribution, and easy reduction characteristics attributed to dopants contribute to the high electrochemical performance for water splitting.
ELECTROCHIMICA ACTA
(2022)
Article
Energy & Fuels
Michael Chukwuemeka Ekwonu, Mirae Kim, Binqi Chen, Muhammad Tauseef Nasir, Kyung Chun Kim
Summary: The parallel expander ORC system improves the partial-load performance of an ORC by switching between various combinations of expanders. This study developed a dynamic model using dual expanders to investigate the dynamic responses during mode changes. Experimental results were used to implement empirical parameters and a control strategy was proposed to prevent droplet formation in the expanders during mode transition. Analysis showed that the optimum shifting time was between 40 to 50 s.
Article
Mechanics
Sajjad Hosseini, Aref Afsharfard, Mehdi Rafati Zarkak, Javad Abolfazli Esfehani, Seungho Kim, Kyung Chun Kim
Summary: The present study investigates the effect of changes on the cross-sectional geometry of a flow-induced vibration-based energy harvester. A bio-inspired geometry, similar to the 'Amaryllis' flower, is utilized for numerical and experimental studies. The study reveals a proportional relation between the enhancement of fluid dynamic forces and the shortening of vortex formation length, and demonstrates that the newly proposed nature-inspired system can effectively increase the amount of harvested energy.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2023)
Article
Optics
Tao Cai, Binqi Chen, Jeongmin Han, Mirae Kim, Eunseop Yeom, Kyung Chun Kim
Summary: This study investigates the effect of excitation duration on the decay of phosphorescence. It is found that the decay time shows an exponential change and saturation phenomenon with the increase of excitation duration. Three possible reasons are proposed and discussed. The results contribute to a better understanding of how excitation duration affects the decay process of phosphorescence.
JOURNAL OF LUMINESCENCE
(2022)
Article
Thermodynamics
Mohammad Parsa Ghofrani Maab, SayedMehrdad Bathaei, Mirae Kim, Javad Abolfazli Esfahani, Kyung Chun Kim
Summary: This study investigated numerically the ammonia/air premixed combustion in conditions relevant to marine engines. It aimed to gain a deeper understanding of ammonia combustion at high pressure and humidity conditions. The effects of mixture equivalence ratio, compression ratio, and relative humidity on essential combustion characteristics were extensively studied. The results showed that increased air humidity could decrease the laminar flame speed but mitigate NO production, without affecting the reaction pathways.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2023)
Article
Computer Science, Interdisciplinary Applications
Shabnam Mohammadshahi, Hadi Samsam-Khayani, Binqi Chen, Tao Cai, Kyung Chun Kim
Summary: This article explores a cost-effective two-dimensional temperature measurement method based on the lifetime technique, which utilizes thermographic phosphor materials to measure surface temperatures. The study analyzes different phosphor-coated samples to study emitted light intensity and temperatures at discrete points. Additionally, a high-speed camera is used to measure surface temperature distributions to ensure coating stability for temperature sensing applications.
JOURNAL OF VISUALIZATION
(2023)
Article
Automation & Control Systems
Yong Eun Lee, Shujun Zhang, Nak Joon Choi, Yoojeong Noh, Kyung Chun Kim
Summary: This study adopts deep learning techniques to detect the misalignment fault of rotating machinery, extracting fault features and reducing dimensions through the t-SNE algorithm, and using the ANN algorithm for fault classification. Compared to the conventional PCA method, the t-SNE algorithm shows higher fault classification accuracy with vibration data.
JOURNAL OF CONTROL AUTOMATION AND ELECTRICAL SYSTEMS
(2023)
Article
Engineering, Mechanical
Golnaz Zarabian Ghaeini, Mohammad Parsa Ghofrani Maab, Sayed Mehrdad Bathaei, Mirae Kim, Javad Abolfazli Esfahani, Kyung Chun Kim
Summary: Ammonia is a promising carbon-free fuel and hydrogen carrier. Blending it with hydrogen can address its low flammability issue. However, there is a lack of microscale data on ammonia combustion. This study uses numerical simulations to investigate the stable flame region, NOx emission, and combustion efficiency of ammonia/hydrogen blends in micro-combustors. The findings suggest that a stable flame cannot be achieved at very low or high inlet velocities, and when the hydrogen fraction is below 60% in the fuel. It is recommended to reduce the inlet velocity to improve combustion efficiency when a higher percentage of ammonia is required in the fuel.
JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING
(2023)
Article
Engineering, Multidisciplinary
Juyong Jung, Mirae Kim, Tao Cai, Yingzheng Liu, Kyung Chun Kim
Summary: Thermographic phosphor thermometry is a widely used non-contact surface temperature measurement method. The damage of chemical bonding coatings during the measurement often leads to the loss of temperature information. In this study, a deep neural network model was proposed to recover the lost data, achieving a prediction accuracy of over 94.94%. However, the model performed relatively poorly in regions with large temperature gradients.
MEASUREMENT SCIENCE AND TECHNOLOGY
(2023)
Article
Engineering, Chemical
Ahmad Kazemi, Mahmood Norouzi, Ali Abbas Nejad, Mirae Kim, Kyung Chun Kim, Seo Gyun Kim
Summary: This study experimentally investigated the immiscible viscoelastic Saffman-Taylor instability in porous media. The viscoelastic displacing fluids used were glycerin, water, and polyacrylamide solutions, while the immiscible displaced fluids were silicone oils with different viscosities. The study analyzed the role and contribution of the first normal stress difference and elongational viscosity in the immiscible viscoelastic displacement, as well as the effects of different parameters on the flow instability.
CHEMICAL ENGINEERING RESEARCH & DESIGN
(2023)
Article
Electrochemistry
Sunghwan Oh, Dohyung Kim, Kyung Chun Kim, Doo-In Kim, Wonsub Chung, Byung-Hyun Shin
Summary: Si wafers used in semiconductors require precise machining and are processed using an STS304 saw wire. Recently, the super duplex stainless steel (SDSS) has shown superior performance compared to STS304 and is suitable for use as a saw wire. Nickel plating was applied to ferritized SDSSs to improve the saw wire performance, and the electrochemical properties were analyzed. The optimal duration for electrolytic nickel plating of ferritized SDSS was found to be 240 s.
INTERNATIONAL JOURNAL OF ELECTROCHEMICAL SCIENCE
(2023)
Article
Thermodynamics
Mohammad Reza Attari, Mahmood Norouzi, Mohammad Hassan Kayhani, Alireza Bakhshinejad Bahambari, Mirae Kim, Kyung Chun Kim
Summary: This study investigates the film cooling performance of oscillating flow on two rows of cooling holes with different arrangements. The results show that flow oscillation can improve the cooling effectiveness of compound angled cooling holes. The frequency of oscillation affects the cooling performance and flow structures.
NUMERICAL HEAT TRANSFER PART A-APPLICATIONS
(2023)
Article
Mechanics
Mohammad Kazam Sheykhian, Mohammad Hasan Kayhani, Mahmood Norouzi, Mirae Kim, Kyung Chun Kim
Summary: This study investigated the impact of Boger droplets on spherical surfaces, considering the effects of various liquid and surface properties for the first time. The researchers examined the rheological properties of the droplets and analyzed the influence of elasticity, elongational viscosity, and the first normal stress difference on the impact of Boger droplets on solid surfaces. The results were compared to those of equivalent Newtonian droplets in terms of viscosity and surface tension coefficient. Additionally, the study explored the effects of Weber number, diameter ratio, and surface wettability on the spreading and receding behaviors of viscoelastic droplets.
Article
Engineering, Aerospace
Pouya Pouyaei, Mohammad Hassan Kayhani, Mahmood Norouzi, Alireza Bakhshinejad Bahambari, Mirae Kim, Kyung Chun Kim
Summary: This numerical study investigated the effects of a curved turning vane on heat transfer and pressure loss in an internal cooling channel. The results showed that the curved turning vane reduced pressure drop and attenuated overall heat transfer, but increased local heat transfer in specific regions.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART G-JOURNAL OF AEROSPACE ENGINEERING
(2023)
Article
Electrochemistry
Sunghwan Oh, Dohyung Kim, Kyungchun Kim, Doo-In Kim, Wonsub Chung, Byung-Hyun Shin
Summary: This study analyzed the effect of surface roughness on the corrosion resistance and re-passivation of SDSS. The findings showed that surface roughness reduces the corrosion potential and increases the corrosion current density, thereby reducing the corrosion resistance. A surface roughness of less than 100 nm is recommended for better corrosion resistance when using SDSS in a corrosive environment.
INTERNATIONAL JOURNAL OF ELECTROCHEMICAL SCIENCE
(2023)
Article
Thermodynamics
Mahsa Taghavi, Swapnil Sharma, Vemuri Balakotaiah
Summary: This study investigates the natural convection effects in the insulation layers of spherical storage tanks and their impact on the tanks' performance. The permeability and Rayleigh number of the insulation material are considered as key factors. The results show that as the Rayleigh number increases, new convective cells emerge and cause the cold boundary to approach the external hot boundary. In the case of large temperature differences, multiple solutions may coexist.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinyang Xu, Fangjun Hong, Chaoyang Zhang
Summary: This study introduces a self-induced jet impingement device for enhancing pool boiling performance in high power electronic cooling. Through visualization and parametric investigations, the effects of this device on pool boiling performance are studied, revealing the promotion of additional liquid supply and vapor exhausting. The flow rate of the liquid jet is found to positively impact boiling performance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Wenchao Ke, Yuan Liu, Fissha Biruke Teshome, Zhi Zeng
Summary: Underwater wet laser welding (UWLW) is a promising and labor-saving repair technique. A thermal multi-phase flow model was developed to study the heat transfer, fluid dynamics, and phase transitions during UWLW. The results show that UWLW creates a water keyhole, making the welding environment similar to in air laser welding.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Xingrong Lian, Lin Tian, Zengyao Li, Xinpeng Zhao
Summary: This study investigates the heat transfer mechanisms in natural fiber-derived porous structures and finds that thermal radiation has a significant impact on the thermal conductivity in low-density regions, while natural convection rarely occurs. Insulation materials derived from micron-sized natural fibers can achieve minimum thermal conductivity at specific densities. Strategies to lower the thermal conductivity include increasing porosity and incorporating nanoscale pores using nanosize fibers.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Yasir A. Malik, Kilian Koebschall, Stephan Bansmer, Cameron Tropea, Jeanette Hussong, Philippe Villedieu
Summary: Ice crystal icing is a significant hazard in aviation, and accurate modeling of sticking efficiency is essential. In this study, icing wind tunnel experiments were conducted to quantify the volumetric liquid water fraction, sticking efficiency, and maximum thickness of ice layers. Two measurement techniques, calorimetry and capacitive measurements, were used to measure the liquid water content and distribution in the ice layers. The experiments showed that increasing wet bulb temperatures and substrate heat flux significantly increased sticking efficiency and maximum ice layer thickness.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinqi Hu, Tongtong Geng, Kun Wang, Yuanhong Fan, Chunhua Min, Hsien Chin Su
Summary: This study experimentally examined the heat dissipation of vibrating fans and demonstrated its inherent mechanism through numerical simulation. The results showed that the flow fields induced by the vibrating blades exhibited pulsating features and formed large-scale and small-scale vortical structures, significantly improving heat dissipation. The study also identified the impacts of different blade structures and developed a trapezoidal-folding blade, which effectively reduced the maximum temperature of the heat source and alleviated high-temperature failure crisis.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Dan-Dan Su, Xiao-Bin Li, Hong-Na Zhang, Feng-Chen Li
Summary: The boiling heat transfer of low-boiling-point working fluid is a common heat dissipation technology in electronic equipment cooling. This study analyzed the interfacial boiling behavior of R134a under different conditions and found that factors such as the initial thickness of the liquid film, solid-liquid interaction force, and initial temperature significantly affect the boiling mode and thermal resistance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinyi Wu, Dongke Sun, Wei Chen, Zhenhua Chai
Summary: A unified lattice Boltzmann-phase field scheme is proposed to simulate dendrite growth of binary alloys in the presence of melt convection. The effects of various factors on the growth are investigated numerically, and the model is validated through comparisons and examinations.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Shaokun Ge, Ya Ni, Fubao Zhou, Wangzhaonan Shen, Jia Li, Fengqi Guo, Bobo Shi
Summary: This study investigated the temperature distribution of main cables in a suspension bridge during fire scenarios and proposed a prediction model for the maximum temperature of cables in different lane fires. The results showed that vehicle fires in the emergency lane posed a greater thermal threat to the cables.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Shuang-Ying Wu, Shi-Yao Zhou, Lan Xiao, Jia Luo
Summary: This paper investigates the two-phase flow and heat transfer characteristics of low-velocity jet impacting on a cylindrical surface. The study reveals that the heat transfer regimes are non-phase transition and nucleate boiling with the increase of heat transfer rate. The effects of jet impact height and outlet velocity on local surface temperatures are pronounced at the non-phase transition stage. The growth rates of heat transfer rate and liquid loss rate increase significantly from the non-phase transition to nucleate boiling stage.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Emad Hasani Malekshah, Wlodzimierz Wlodzimierz, Miros law Majkut
Summary: Cavitation has significant practical importance and can be controlled by air injection. This study investigates the natural to ventilated cavitation process around a hydrofoil through numerical and experimental methods. The results show that the location and rate of air injection have a meaningful impact on the characteristics of cavitation.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Feriel Yahiat, Pascale Bouvier, Antoine Beauvillier, Serge Russeil, Christophe Andre, Daniel Bougeard
Summary: This study explores the enhancement of mixing performance in laminar flow equipment by investigating the generation of chaotic advection using wall deformations in annular geometries. The findings demonstrate that the combined geometry can achieve perfect mixing at various Reynolds numbers.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Hui He, Ning Lyu, Caihua Liang, Feng Wang, Xiaosong Zhang
Summary: This study investigates the condensation, frosting, and defrosting processes on superhydrophobic surfaces with millimeter-scale structures. The results reveal that the structures can influence the growth and removal of frost crystals, with the bottom grooves creating a frost-free zone and conical edges promoting higher frost crystal heights. Two effective methods for defrosting are observed: hand-lifting the groove and airfoil retraction contraction on protruding structures. This research provides valuable insights into frost formation and defrosting on millimeter-structured superhydrophobic surfaces, with potential applications in anti-frost engineering.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Thiwanka Arepolage, Christophe Verdy, Thibaut Sylvestre, Aymeric Leray, Sebastien Euphrasie
Summary: This study developed two thermal concentrators, one with a 2D design of uniform thickness and another with a 3D design, using the coordinate transformation technique and metamaterials. By structuring the thermal conductor, the desired local density-heat capacity product and anisotropic thermal conductivities were achieved. The homogenized thermal conductivities were obtained from finite element simulations and cylindrical symmetry consideration. A 3D concentrator was fabricated using 3D metal printing and characterized using a thermal camera. Compared to devices that solely consider anisotropic conductivities, the time evolution characteristics of the metadevice designed with coordinate transformation were closer to those of an ideal concentrator.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Liangyuan Cheng, Qingyang Wang, Jinliang Xu
Summary: In this study, we investigated the supercritical heat transfer of CO2 in a horizontal tube with a diameter of 10.0 mm, covering a wide range of pressures, mass fluxes, and heat fluxes. The study revealed a non-monotonic increase in wall temperatures along the flow direction and observed both positive and negative wall temperature differences between the bottom and top tube. The findings were explained by the thermal conduction in the solid wall interacting with the stratified-wavy flow in the tube.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
