Driver Fatigue Detection System based on Eye Blinking by Convolutional Neural Network

Zhichao Sun,Yinan Miao,전준영,박규해 한국자동차공학회 2022 한국자동차공학회 지부 학술대회 논문집 Vol.2022 No.12

Deep Learning-based Driver Fatigue Detection System

Sun Zhichao,Yinan Miao,Jun Young Jeon,Gyuhae Park 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.5

Comparative Evaluation: Passenger Satisfaction and Operation Efficiency of Different Even-Headway and Even-Load Public Transport Timetables

Zhichao Cao,Ting Xu,Silin Zhang,Avishai (Avi) Ceder,Yuyao Sun 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.7

Even-headway timetables with easy to memorize departure times are commonly in use in public transport (PT) service. In addition, some PT services are using timetables where their departure times are based on even-passenger-load at the max-load stop along the route. In practice, these two types of timetables are implemented in daily operation plans, allowing for their merits, with the former maintaining the initial, even-interval departure rules and conventions, especially when a new PT line is planned without available demand information, while the latter is demand-oriented, exhibiting fluctuation in time and space. The principles of creating the aforementioned timetables have been presented in the literature, but very few evaluations feasibly attest to performance by means of mathematical analysis. Concentrating on building a modelling framework for PT timetabling problems during the planning stage, this work is taking into account 1) passengers’ service-frequency satisfaction, in terms of waiting times, 2) passengers’ perception of riding comfort, in terms of seat availability, and 3) planned passengers’ load ratio (concerning vehicle’s capacity) linked with operation efficiency. Yielding to the models developed in a theoretical manner, the comparative evaluation is conducted through multiple timetable schemes that include four different dimensions: (A) even-headway departures with same headway throughout the time horizon, (B) even-load departures with same load throughout the time horizon, (C) even-headway departures for each demand-dependent period, and (D) even-load departures for each demand-dependent period. Finally, a case study in Nantong, China examines the comparison performances produced and the best plans for operational timetables. The results indicate that travelers attributed great importance to higher satisfaction preferences on frequency or headway-related experience linked with their waiting time.

Production of Xylooligosaccharides from Corncobs Using Ultrasound-assisted Enzymatic Hydrolysis

Juntao Sun,Zhichao Zhang,Fugang Xiao,Ximei Jin 한국식품과학회 2015 Food Science and Biotechnology Vol.24 No.6

Xylooligosaccharides were obtained using ultrasound-assisted enzymatic hydrolysis from xylan that was alkali extracted from corncobs. Effects of alkali treatments on xylan extraction were investigated. The influence of operational conditions in ultrasound-assisted enzymatic hydrolysis on xylooligosaccharide production was also studied. Optimal conditions for xylan extraction were determined to be an alkaline concentration of 15%, a corncobs to alkaline solution ratio of 1:20, a reaction temperature of 100°C, and a reaction time of 2 h. Optimal conditions for xylanase-catalyzed hydrolysis of xylan to xylooligosaccharides were determined to be an enzyme concentration of 4 g/L, an ultrasound power of 200 W, a reaction temperature of 50°C and a reaction time of 10 min. Using a combination of ultrasound and enzyme increased the reducing sugar content by approximately 50%, compared with using of enzymes alone. Ultrasound and enzymes exert a synergistic effect.

An Algorithm of Clustering by Density Peaks Using in Anomaly Detection

Chunyong Yin,Sun Zhang,Zhichao Yin,Jin Wang 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.12

With the development of the networks, the security of computer networks is becoming more and more serious. The information openness, sharing and interconnection are three important characteristics of computer networks. However, the amounts of intruders and attackers have been grows with the popularization of computers. Therefore, the focus of network security is preventing systems from being invaded effectively. Intrusion detection as a key technology of network security active defense system is designed to distinguish normal behaviors and attack behaviors. Intrusion detection is divided into misuse detection and anomaly detection, and using clustering algorithm is one of the most effective methods for anomaly detection. In this paper, a clustering algorithm based on fast search and find of density peaks is used to distinguish the normal and abnormal network connections to achieve the purpose of anomaly detection. The performance of the algorithm is tested by a data set selected from KDD CUP99. Experiment results show that this algorithm is more suitable than the traditional K-means in data sets containing a large amount of data and uneven density distribution.

A New FE Modeling Method for Isothermal Local Loading Process of Large-scale Complex Titanium Alloy Components Based on DEFORM-3D

Dawei Zhang,He Yang,Zhichao Sun,Xiaoguang Fan 한국소성가공학회 2010 기타자료 Vol.2010 No.6

Isothermal local loading process provides a new way to form large-scale complex titanium alloy components. The forming process is characterized by an extreme size (large scale in global and compared small size in regional), multi-parameter effects, and complicated loading path. To establish a reasonable finite element model is one of the key problems urgently to be solved in the research and development of isothermal local loading forming process of largescale complex titanium alloy components. In this paper, a new finite element model of the isothermal local loading process is developed under the DEFORM-3D environment based on the solution of some key techniques. The modeling method has the following features: (1) different meshing techniques are used in different loading areas and the number of meshed elements is determined according to the deformation characteristic in different local loading steps in order to improve computational efficiency; (2) the accurate magnitude of the friction factor under titanium alloy hot forming (isothermal forming) condition is adopted instead of the typical value for lubricated hot forming processes; (3) different FEM solvers are chosen at different stages according to the loading characteristic and the contact state; (4) in contrast to the local component model, a full 3D component is modeled to simulate the process. The 3D-FE model is validated by experimental data of a large-scale bulkhead forming under isothermal local loading. The model can describe the quantitative relationships between the forming conditions and the forming results. The results of the present study may provide a basis for studying the local deformation mechanism, selecting the reasonable parameters, optimizing the die design and the process control in isothermal local loading process of large-scale complex titanium alloy components.

Numerical Simulation of the Creep Behavior of Beishan Deep Granite Tunnel under the Coupling Thermal -Stress Field

Jiawei Wang,Ju Wang,Zhichao Zhou,Peng Wu,Haoran Sun,Jiale Dou,Nan Li,Xianzhe Duan 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.4

This study conducts a three-dimensional numerical simulation of the creep behavior of deep granite tunnels at 560 meters underground during the coupled thermal-stress process, with an aim to elucidate the effect of the temperature and stress fields on the creep behavior of these deep hard rock tunnels. A 100-h creep period was set, and the mechanical structure of the experimental chamber was accurately replicated at a 1:1 scale, considering the actual mechanical structure of the granite tunnels in the Beishan underground laboratory. The simulation results can demonstrate that: 1) The maximum stress at 90°C and 50°C are 2.86 and 1.91 times than that at 23°C, respectively, demonstrating significant strain accumulation in the deep granite tunnels at the surface. This phenomenon can primarily be attributed to the thermal stress resulted from the coupling between temperature and stress. 2) The maximum creep at 90°C and 50°C is 16 and 3.5 times than that at 23°C. Under the influence of thermal coupling, the creep increases significantly with increasing temperature, indicating that temperature is an important factor influencing creep in granite. 3) Compared with variations in the stress field, the temperature field emerges as the most critical factor influencing granite creep.

Characterization and performance test of phenolphthalein poly(aryl ether ketone) fractionated by incremental poor solvent fractionation

Zengxu Qian,Jingwei Jiang,Yunlong Sun,Qiliang Yuan,Zhichao Wang,Zhipeng Wang,Guangyuan Zhou 한국고분자학회 2023 Macromolecular Research Vol.31 No.8

Though phenolphthalein poly(aryl ether ketone) (PEK-C) has gained attention as a special engineering plastic materials by virtue of its good thermal stability and favorable mechanical properties, its applications are limited due to its wide PDI during polymerization, which result in poor mechanical properties of PEK-C. In order to investigate the effect of molecular weight and polydispersity index (PDI) on PEK-C, an incremental poor solvent fractionation method was used to fractionate PEK-C. The process produced a series of grades with decreasing molecular weight and PDI. The LCP (linear cloud point) equation was combined with the grading method to find the optimal PEK-C/DMAc/ Non-solvent additives (NSA) system, which can be used to improve the grading efficiency. The obtained results showed that the incremental poor solvent fractionation method with the PEK-C/DMAc/EA system made the molecular weight distributed in the range of 25 ~ 113 kDa, PDI mostly distributed in the range of 1.1 ~ 1.4, and the narrowest PDI to reach 1.13, which could not be obtained through the condensation reaction. Meanwhile, we can also achieve expanded production. By fractionation, the elastic modulus of PEK-C film could be increased by up to 22.6%, elongation at break by up to 38.3%, the fracture strength by up to 38.2%, and impact strength of the sheest by up to 41.2%, while the polymer still maintained good thermal and UV shielding properties. This unique Polymer/Solution/NSA system can yield an effective design strategy for controlling its molecular weight and PDI and improving its mechanical performance.