A Hazard-Based Duration Model to Quantify the Impact of Work-Related Distraction on Taxi Drivers’ Safety Performance: A Driving Simulator Study

Tiantian Chen,Shi Ye,Oscar Oviedo-Trespalacios,N.N. Sze 대한교통학회 2023 대한교통학회 학술대회지 Vol.89 No.-

Distractions by Work-related Activities: The Impact of Ride-hailing App and Radio System on Male Taxi Drivers

Tiantian (Nicole) Chen,Oscar Oviedo-Trespalacios,N.N. Sze,Sikai Chen 대한교통학회 2023 대한교통학회 학술대회지 Vol.88 No.-

Use of ride-hailing mobile apps has surged and reshaped the taxi industry. These apps allow real-time taxi-customer matching of taxi dispatch system. However, there are also increasing concerns for driver distractions as a result of these ride-hailing systems. This study aims to investigate the effects of distractions by different ride-hailing systems on the driving performance of taxi drivers using the driving simulator experiment. In this investigation, fifty-one male taxi drivers were recruited. During the experiment, the road environment (urban street versus motorway), driving task (free-flow driving versus car-following), and distraction type (no distraction, auditory distraction by radio system, and visual-manual distraction by mobile app) were varied. Repeated measures ANOVA and random parameter generalized linear models were adopted to evaluate the distracted driving performance accounting for correlations among different observations of a same driver. Results indicate that distraction by mobile app impairs driving performance to a larger extent than traditional radio systems, in terms of the lateral control in the free-flow motorway condition and the speed control in the free-flow urban condition. In addition, for car-following task on urban street, compensatory behaviour (speed reduction) is more prevalent when distracted by mobile app while driving, compared to that of radio system. Additionally, no significant difference in subjective workload between distractions by mobile app and radio system were found. Several driver characteristics such as experience, driving records, and perception variables also influence driving performances. The findings are expected to facilitate the development of safer ride-hailing systems, as well as driver training and road safety policy.

A Hazard-Based Duration Model to Quantify the Impact of Work-Related Distraction on Taxi Drivers’ Safety Performance: A Driving Simulator Study

Tiantian Chen,Shi Ye,Oscar Oviedo-Trespalacios,N.N. Sze 대한교통학회 2023 대한교통학회 학술대회지 Vol.89 No.-

Rough tool path generation for NC machining of Loop subdivision surfaces

Tiantian Chen,Gang Zhao (사)한국CDE학회 2013 한국CAD/CAM학회 국제학술발표 논문집 Vol.2010 No.8

Subdivision surface modeling plays an important role in the field of surface modeling. As the gradual progress of subdivision is discrete, both a smooth design model and a discrete machining model can be represented by subdivision surface. Particularly, due to the unique multiresolution property, different multiresolution models can be obtained by utilizing subdivision wavelets analysis filters. Therefore, different multiresolution models can be applied to generate tool paths at different NC machining stages. Firstly, the paper is mainly focused on the key technologies of Loop subdivision surface multiresolution analysis. The biorthogonal Loop subdivision wavelets decomposition and reconstruction based on the reverse subdivision are realized and verified experimentally. Both the error control and boundary treatment are discussed. Secondly, special attention is paid to the tool path generation of rough machining based on reverse Loop subdivision surface. By making use of reverse Loop subdivision wavelets and adjustment algorithms of local control points, the smooth rough machining model with minimum energy is generated. Finally, machining simulation tests are implemented for the verification.

Experimental study on thermo-hydraulic performance of nanofluids in diverse axial ratio elliptical tubes with a built-in turbulator

Cong Qi,Tiantian Chen,Yuxing Wang,Liyuan Yang 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.9

Due to the low heat transfer efficiency of common heat exchange systems, an improved heat exchange system was developed. Enhanced tubes (elliptical tubes with a built-in turbulator) instead of a smooth tube were used and TiO2-water nanofluids were substituted for water to intensify the heat transfer. The influences of turbulator (presence or absence), axial ratios of elliptical tubes (Z=1.235, 1.471, 1.706), nanoparticle concentration (=0.0 wt%, 0.1 wt%, 0.3 wt%, 0.5 wt%), and Reynolds number (Re=400-12,000) on the flow and heat transfer properties of TiO2-water nanofluids were studied. Thermal and exergy efficiency were used to research the comprehensive thermo-hydraulic characteristics of these heat transfer enhancement technologies. The thermo-hydraulic properties of nanofluids all showed an increasing trend with the growing axial ratio, nanoparticle concentration and Reynolds number. Nanofluids (=0.5 wt%) in an elliptical tube (Z=1.706) with a built-in turbulator showed the best thermal performance, which could be increased by 33.8% in comparison with water at best. The thermal efficiency index increased first and then decreased with the Re. Nanofluids in elliptical tubes with a built-in turbulator can clearly promote heat transfer under the identical condition.

Effects of heat sink structure on heat transfer performance cooled by semiconductor and nanofluids

Cong Qi,Tiantian Chen,Jianglin Tu,Yuxing Wang 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.12

On account of the low heat dissipation problem of common cooling systems, an experimental system with enhanced structures was set to improve the heat transfer of heat sink cooled by semiconductor and TiO2-water nanofluids. The influences of structures (smooth surface, metal foam with PPI=30, cylindrical bulge (height: H=2mm, staggered arrangement), cylindrical groove (depth: D'=2 mm, staggered arrangement)), nanoparticle mass fractions (= 0.0-0.5 wt%), input power of the semiconductor (P=2W, 4W, 6W), and Reynolds numbers (Re=414-1,119) on the flow and heat transfer properties of TiO2-water nanofluids were studied. The compositive thermal and hydraulic properties of the enhanced technologies were analyzed by thermal efficiency. Results indicated that the combination of semiconductor and metal foam shows the most excellent performance compared with other combinations and it can be enhanced by 48.1% at best. Nanofluids with =0.4 wt% display the best cooling capacity instead of the highest concentration. The cooling effect shows an increasing trend with the input power of the semiconductor.

Automatic identification and analysis of multi-object cattle rumination based on computer vision

Yueming Wang,Tiantian Chen,Baoshan Li,Qi Li 한국축산학회 2023 한국축산학회지 Vol.65 No.3

Rumination in cattle is closely related to their health, which makes the automatic monitoring of rumination an important part of smart pasture operations. However, manual monitoring of cattle rumination is laborious and wearable sensors are often harmful to animals. Thus, we propose a computer vision-based method to automatically identify multi-object cattle rumination, and to calculate the rumination time and number of chews for each cow. The heads of the cattle in the video were initially tracked with a multi-object tracking algorithm, which combined the You Only Look Once (YOLO) algorithm with the kernelized correlation filter (KCF). Images of the head of each cow were saved at a fixed size, and numbered. Then, a rumination recognition algorithm was constructed with parameters obtained using the frame difference method, and rumination time and number of chews were calculated. The rumination recognition algorithm was used to analyze the head image of each cow to automatically detect multi-object cattle rumination. To verify the feasibility of this method, the algorithm was tested on multi-object cattle rumination videos, and the results were compared with the results produced by human observation. The experimental results showed that the average error in rumination time was 5.902% and the average error in the number of chews was 8.126%. The rumination identification and calculation of rumination information only need to be performed by computers automatically with no manual intervention. It could provide a new contactless rumination identification method for multi-cattle, which provided technical support for smart pasture.

Ginsenoside Re inhibits myocardial fibrosis by regulating miR-489/myd88/NF-κB pathway

Jinghui Sun,Ru Wang,Tiantian Chao,Jun Peng,Chenglong Wang,Keji Chen The Korean Society of Ginseng 2023 Journal of Ginseng Research Vol.47 No.2

Background: Myocardial fibrosis (MF) is an advanced pathological manifestation of many cardiovascular diseases, which can induce heart failure and malignant arrhythmias. However, the current treatment of MF lacks specific drugs. Ginsenoside Re has anti-MF effect in rat, but its mechanism is still not clear. Therefore, we investigated the anti-MF effect of ginsenoside Re by constructing mouse acute myocardial infarction (AMI) model and AngII induced cardiac fibroblasts (CFs) model. Methods: The anti-MF effect of miR-489 was investigated by transfection of miR-489 mimic and inhibitor in CFs. Effect of ginsenoside Re on MF and its related mechanisms were investigated by ultrasonographic, ELISA, histopathologic staining, transwell test, immunofluorescence, Western blot and qPCR in the mouse model of AMI and the AngII-induced CFs model. Results: MiR-489 decreased the expression of α-SMA, collagenI, collagen III and myd88, and inhibited the phosphorylation of NF-κB p65 in normal CFs and CFs treated with AngII. Ginsenoside Re could improve cardiac function, inhibit collagen deposition and CFs migration, promote the transcription of miR-489, and reduce the expression of myd88 and the phosphorylation of NF-κB p65. Conclusion: MiR-489 can effectively inhibit the pathological process of MF, and the mechanism is at least partly related to the regulation of myd88/NF-κB pathway. Ginsenoside Re can ameliorate AMI and AngII induced MF, and the mechanism is at least partially related to the regulation of miR-489/myd88/NF-κB signaling pathway. Therefore, miR-489 may be a potential target of anti-MF and ginsenoside Re may be an effective drug for the treatment of MF.

Leaching Characteristics of Iron and Manganese from Steel Slag with Repetitive Replenishment of Leachate

Longxi Han,Bo Chen,Tiantian Liu,최용주 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.8

Steel slag reuse as a construction material is an attractive solution for the management of the industrial byproduct. However, concern exists on the release of steel slag constituents when a massive amount of the material is reused in the field. This study is aimed to improve the understanding on the leaching characteristics of iron and manganese, two heavy metals that are present in steel slag at relatively high contents. Concentrations of iron and manganese in the batch leaching experiment readily reach close to equilibrium within 1 hour. Batch leaching experiments conducted with exchange of the leaching solution at 1 hour intervals show that the leaching occurs consistently with relatively constant concentration up to 50 events of exchange. The leaching is a strong function of salinity showing factors of 11.6 and 3.8 increase in iron and manganese leachate concentrations, respectively. Despite the wide size ranges (<0.5 to >25 mm) tested, effect of slag grain size is less pronounced compared to the salinity effect. The average concentration in the leachate for 50 leaching events is sub-mg L−1 level for iron at most and an order of magnitude lower for manganese than the value for iron. These results show that steel slag is an almost permanent but a very low-level source of iron and manganese when reused in the environment.

Dynamic colonization of gut microbiota and its influencing factors among the breast-feeding infants during the first two years of life

Li Ping,Chang Xuelian,Chen Xiaoyu,Tang Tiantian,Liu Yajing,Shang Yu,Qi Kemin 한국미생물학회 2022 The journal of microbiology Vol.60 No.8

The maturation of infant gut microbiota has lifelong implications on health, which has been proposed as the major events during the first year of life. However, little is known about their dynamic colonization and influencing elements among the first two-year infancy as well as into the adulthood. So based on the 16S rRNA sequencing data among 30 healthy breast-feeding mother-infant pairs with normal ranges of growth and development indicators from birth to two years old, the dynamic colonization of gut microbiota and its influencing factors were discussed using this birth cohort. Among these, we identified that the diversity of gut microbiota was significantly increased from six-month to two-year subgroups. The significantly dynamic trends of gut microbiota at the phylum (genus) level were that the percents of Firmicutes (Faecalibacterium, Blautia, Enterococcus, Subdoligranulum, Agathobacter, unidentified_Erysipelotrichaceae, Staphylococcus, unidentified_Ruminococcaceae, and Fusicatenibacter), Bacteroidetes and Verrucomicrobia were increased, while Actinobacteria (Bifidobacterium) and Proteobacteria (unidentified- Enterobacteriaceae and Klebsiella) were decreased with the increased ages from six months to two years old, which might simultaneously modulate the host pathways, such as the higher percents of chemoheterotrophy and fermentation, and lower percentages of nitrate_reduction, aerobic_chemoheterotrophy and so on. Furthermore, there were significant associations between maternal (milk microbiota, pre-pregnancy BMI, BMI increment during the pregnancy)/infant characteristics (BMI at birth and BMI gain), and the compositions of gut microbiota. However, no differences of gut microbiota were shown between the different sex and productive mode subgroups. Overall, the colonization of gut microbiota is significantly matured into the adulthood with the increased ages to two-years old and regulated by the above maternal/infant characteristics, which will provide a new direction for the host-gut microbiota interplay during the first two years of life.