Simulation of the Optimized Thermal Conductivity of a Rigid Polyurethane Foam during Its Foaming Process

Siyu An,Galen J. Suppes,Tushar K. Ghosh 한국섬유공학회 2019 Fibers and polymers Vol.20 No.2

Thermal conductivity (λ) of a rigid polyurethane (PU) foam plays a vital role in determining the performance of thermal insulation. To accurately predict this property for a given recipe in a few seconds is the first step towards striking a balance between compressive strength, λ, and more properties of a foam product in industrial applications duringformulation. What experimentally observed from PU closed-cell foams made from PAPI-27 Polymeric Methylene Diphenyl Diisocyanate (PMDI), Voranol 360, and n-pentane were: (1) foam shrinkage and even collapse occurred on both low (typically less than 0.9) and ultra-high (close to 2.0) indexes of isocyanate (IA); (2) to achieve the lowest λ for the best thermal insulation, it was suggested to use the highest IA without any foam shrinkage, the fastest stirring rate under safety, and the least physical blowing agent (PBA) until a sharp turn in the trend of λ; (3) there was a definite link between foam density (ρf), closed cell content (ccc), and λ: (a) a low λ requested a high ρf and ccc (b) a denser foam could be achieved by at least three ways. Increasing the agitation rate had a limit, above which the change in density became insignificant. However, a higher IA and reducing the amount of PBA had always been linear with ρf. (c) ρf was the cornerstone of ccc. In low ρf range, a growth of density gave rise to a distinct improvement of ccc, beyond which ccc reached a plateau for any higher density. The foam thermal conductivity during polymerization was successfully simulated by Matlab with 0.0157 % deviation. λ was initially dominated by the contribution from the resin mixture until the gel reaction time. Then, the dominant was shifted to the contribution by the gas component. The magnitude of thermal radiation was rather low throughout the reaction.

Effects of high power pulsed microwave on the enhanced color and flavor of aged blueberry wine

Siyuan Liu,Shuangjian Li,Siyuan Li,Ying Wang,Linlin Fan,Jianzhong Zhou 한국식품과학회 2024 Food Science and Biotechnology Vol.33 No.1

A new method of high-power pulsed microwave (HPPM) was applied to accelerate the aging of blueberry wine. The color changes of blueberry wines during aging were investigated through Chemical Wine Age and CIE-LAB measurement. Results showed that the blueberry wines treated by HPPM at low frequencies (50 and 100 Hz) exhibited improved color characteristics with L* value reaching 47.04 at 100 Hz, an increased maturity of wine body, and a shortened chemical wine age from 90 days to 75 days. Moreover, the aroma changes determined by GC-MS showed that HPPM accelerated the formation of esters in blueberry wine, which were increased by 18.44% and 56.97% respectively under the conditions of 50 and 150 Hz. The formation of acid substances was reduced compared with the original wine, with contents of acetic acid, caproic acid, and octanoic acid of 29.46 µg/mL, 15.60 µg/mL, 17.74 µg/mL, respectively, displaying an enhanced wine flavor.

Evaluating the accuracy and relevance of ChatGPT responses to frequently asked questions regarding total knee replacement

( Siyuan Zhang ),( Zi Qiang Glen Liau ),( Kian Loong Melvin Tan ),( Wei Liang Chua ) 대한슬관절학회 2024 대한슬관절학회지 Vol.36 No.-

Background Chat Generative Pretrained Transformer (ChatGPT), a generative artificial intelligence chatbot, may have broad applications in healthcare delivery and patient education due to its ability to provide human-like responses to a wide range of patient queries. However, there is limited evidence regarding its ability to provide reliable and useful information on orthopaedic procedures. This study seeks to evaluate the accuracy and relevance of responses provided by ChatGPT to frequently asked questions (FAQs) regarding total knee replacement (TKR). Methods A list of 50 clinically-relevant FAQs regarding TKR was collated. Each question was individually entered as a prompt to ChatGPT (version 3.5), and the first response generated was recorded. Responses were then reviewed by two independent orthopaedic surgeons and graded on a Likert scale for their factual accuracy and relevance. These responses were then classified into accurate versus inaccurate and relevant versus irrelevant responses using preset thresholds on the Likert scale. Results Most responses were accurate, while all responses were relevant. Of the 50 FAQs, 44/50 (88%) of ChatGPT responses were classified as accurate, achieving a mean Likert grade of 4.6/5 for factual accuracy. On the other hand, 50/50 (100%) of responses were classified as relevant, achieving a mean Likert grade of 4.9/5 for relevance. Conclusion ChatGPT performed well in providing accurate and relevant responses to FAQs regarding TKR, demonstrating great potential as a tool for patient education. However, it is not infallible and can occasionally provide inaccurate medical information. Patients and clinicians intending to utilize this technology should be mindful of its limitations and ensure adequate supervision and verification of information provided.

Cross-Shaped Magnetic Coupling Structure for Electric Vehicle IPT Charging Systems

Siyuan Ren,Chenyang Xia,Limin Liu,Xiaojie Wu,Qiang Yu 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.4

Inductive power transfer (IPT) technology allows for charging of electric vehicles with security, convenience and efficiency. However, the IPT system performance is mainly affected by the magnetic coupling structure which is largely determined by the coupling coefficient. In order to get this applied to electric vehicle charging systems, the power pads should be able to transmit stronger power and be able to better sustain various forms of deviations in terms of vertical, horizontal direction and center rotation. Thus, a novel cross-shaped magnetic coupling structure for IPT charging systems is proposed. Then an optimal cross-shaped magnetic coupling structure by 3-D finite-element analysis software is obtained. At marking locations with average parking capacity and no electronic device support, a prototype of a 720*720mm cross-shaped pad is made to transmit 5kW power at a 200mm air gap, providing a 1.54m2 full-power free charging zone. Finally, the leakage magnetic flux density is measured. It indicates that the proposed cross-shaped pad can meet the requirements of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) according to the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA).

Fouling characteristics of MgO particles under subcooled flow boiling

Siyuan Wang,Zhiming Xu,Jingtao Wang 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.3

In order to investigate the particulate fouling characteristics, experiments of water based magnesia particulate suspensions were carried out in an annular test section under subcooled flow boiling. The sizes of magnesia particles were 40 nm and 10 μm, respectively. The influence of particle concentration, heat flux, mass flow rate and inlet temperature on fouling resistance were investigated, and the Chilton-Colburn analogy was applied to analyze the fouling process. The results show that the asymptotic value of fouling resistance increases with the increase of particle concentration. The asymptotic value of fouling resistance tends to fall when mass flow rate increases. As inlet temperature increases, there will be an obvious drop in the asymptotic value of fouling resistance. Regarding to heat flux, opposite variation trend was found between nano and micro-magnesia particles when changing the heat flux. Moreover, there is an obvious difference in asymptotical value of fouling resistance between nano-particles and micro-particles.

Aerodynamic coefficients of inclined and yawed circular cylinders with different surface configurations

Siyuan Lin,Mingshui Li,Haili Liao 한국풍공학회 2017 Wind and Structures, An International Journal (WAS Vol.25 No.5

nclined and yawed circular cylinder is an essential element in the widespread range of structures. As one of the applications, cables on bridges were reported to have the possibility of suffering a kind of large amplitude vibration called dry galloping. In order to have a detailed understanding of the aerodynamics related to dry galloping, this study carried out a set of wind tunnel tests for the inclined and yawed circular cylinders. The aerodynamic coefficients of circular cylinders with three surface configurations, including smooth, dimpled pattern and helical fillet are tested using the force balance under a wide range of inclination and yaw angles in the wind tunnel. The Reynolds number ranges from 2 X105 to 7X105 during the test. The influence of turbulence intensity on the drag and lift coefficients is corrected. The effects of inclination angle yaw angle and surface configurations on the aerodynamic coefficients are discussed. Adopting the existed the quasi-steady model, the nondimensional aerodynamic damping parameters for the cylinders with three kinds of surface configurations are evaluated. It is found that surface with helical fillet or dimpled pattern have the potential to suppress the dry galloping, while the latter one is more effective.

Third Party Funding for Dispute Resolution

Siyuan Jin,Wei Shen 이준국제법연구원 2023 China and WTO Review Vol.9 No.1

Patriotin und heilige Frau? Überlegungen zur Konstruktion und Aktualität eines Figurentypus in Schillers Die Jungfrau von Orleans

Siyuan Huang 한독문학번역연구소 2023 아시아학생독문학자대회 발표문 Vol.2023 No.7

Effects of Aging on Temporal Lobe Blood Flow with Structural Correction in Healthy Older Adults

( Siyuan Hu ),( Hengyi Rao ),( Lauren Mancuso ),( Senhua Zhu ),( John A. Detre ),( David A. Wolk ) 서울대학교 인지과학연구소 2011 Journal of Cognitive Science Vol.12 No.2

Aging has been associated with both cerebral blood flow (CBF) reductions and structural changes, particularly in the medial temporal lobe (MTL) region. However, it remains unclear whether the decline of CBF in the MTL is due entirely or just partially to anatomical changes. In the present study, pseudocontinuous arterial spin labeling (ASL) was used to measure quantitative CBF in forty-one healthy older adults. High-resolution T1-weighted structure images were also acquired from each subject. Robust age-related CBF decline and anatomical changes were observed in the medial and superior temporal lobe. After controlling for partial volume effect (PVE) and brain atrophy, there were still significant age-related regional CBF decreases in the right parahippocampus and the bilateral insula. However, regional CBF in the left parahippocampal gyrus was not correlated with age after PVE correction. Our results support the importance of structural correction for regional CBF quantification in aging populations and suggest that anatomical changes alone cannot explain the regional CBF decline in older adults.

Effects of Aging on Temporal Lobe Blood Fflow with Structural Correction in Healthy Older Adults

Siyuan Hu,Hengyi Rao,Lauren Mancuso,Senhua Zhu,John A. Detre,David A. Wolk 서울대학교 인지과학연구소 2011 Journal of Cognitive Science Vol.12 No.2

Aging has been associated with both cerebral blood flow (CBF) reductions and structural changes, particularly in the medial temporal lobe (MTL) region. However, it remains unclear whether the decline of CBF in the MTL is due entirely or just partially to anatomical changes. In the present study, pseudocontinuous arterial spin labeling (ASL) was used to measure quantitative CBF in forty-one healthy older adults. High-resolution T1-weighted structure images were also acquired from each subject. Robust age-related CBF decline and anatomical changes were observed in the medial and superior temporal lobe. After controlling for partial volume effect (PVE) and brain atrophy, there were still significant age-related regional CBF decreases in the right parahippocampus and the bilateral insula. However, regional CBF in the left parahippocampal gyrus was not correlated with age after PVE correction. Our results support the importance of structural correction for regional CBF quantification in aging populations and suggest that anatomical changes alone cannot explain the regional CBF decline in older adults.