Impact of Intersecting Angles on Evacuation Efficiency of Pedestrian Flows in High Volume: A Case Study in Metro Station

Manman Chen,Jinghong Wang,Youran Zhi,Jinhua Sun 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.5

The intersection of pedestrian flows is a general phenomenon in daily pedestrian traffic and emergency evacuation. However, lacking of effective controls in crowed areas will result in pedestrian deceleration, stopping, and even threats to safety in evacuation. This paper focused on exploring the influence of different intersecting angles on evacuation efficiency of pedestrian flows in high volume. Through establishing a bidirectional pedestrian flow model with different intersecting angles for a busy metro station in China based on the social force model, two factors, namely the impact between pedestrians and the conflict frequency, were firstly proposed and validated as that playing major roles in influencing the evacuation efficiency during the pedestrian intersection. With the case study, it is found that the best intersecting angle is 120 degree and angles between 40 and 80 degree are unfavorable in optimizing the average crowd speed and the crowd density. The results are verified based on the comparative analysis with some existing experimental results. The outcomes of this work can offer some guidelines to control the intersection of pedestrian flows during evacuation and can make contributions to a proposal for the related, optimized design of a structure to increasing the evacuation efficiency of a dense crowd.

DNA hypermethylation level of ACTL6A may promote BmNPV infection in B. mori

Chen Zikang,Huang Haoling,Yin Haotong,Shen Manman,Guo Xijie,Wuping Liao 한국응용곤충학회 2022 Journal of Asia-Pacific Entomology Vol.25 No.2

Bombyx mori nucleopolyhedrosis virus (BmNPV) can cause acute virus disease in silkworm, seriously endan gering the sustainable development of sericultural industry. DNA methylation is an extensive regulation mode of gene expression in epigenetics, which plays an important role in a series of life processes such as genomic imprinting, embryo development, aging and viral infection. Previously, we found the DNA hypermethylation of actin-like protein 6A gene (ACTL6A) in BmNPV-infected midgut of silkworm larvae by whole genome bisulfite sequencing. In this study, firstly, we validated the enhanced transcription level and the DNA methylation level of ACTL6A in the midgut upon BmNPV infection by qRT-PCR and BS-PCR, respectively. Then, treated the BmN cells with DNA methylation inhibitor (Zebularine), both the DNA methylation level and the transcription level of ACTL6A were declined. Further, knock down of ACTL6A by siRNA inhibited the proliferation of BmNPV. The results showed that BmNPV infection may induce the DNA hypermethylation of ACTL6A in Bombyx mori, which promoted the transcription level of ACTL6A, and then affected the proliferation of BmNPV. Our results may provide an insight into exploring the role of DNA methylation in the interaction between BmNPV and silkworm.

A Data-driven Approach to Estimate the Probability of Pedestrian Flow Congestion at Transportation Bottlenecks

Jinghong Wang,Manman Chen,Wenyu Yan,Youran Zhi,Zhirong Wang 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.1

In public gathering places, pedestrian flow congestion may happen in transportation bottlenecks. Limitations exist in the conventional judgment of congestion by considering the crowd density or the walking speed merely. In this paper, a data-driven mathematical approach based on Kernel Density Estimation (KDE) to analyze the probability of pedestrian flow congestion is proposed, which comprehensively considers the walking speed, the crowd density and the flow rate when pedestrians walk towards possible bottlenecks. With the case study of Nanjing metro station during rush hours, the advantages of non-parametric KDE compared with traditional parametric normal distribution estimation are analyzed and the optimal bandwidth for KDE is also discussed. The case study shows that the proposed method can obtain a more reliable quantitative assessment of congestion risk, as it overcomes the limitation of parametric estimation that relies on experience, and also avoids biased assessment of congestion that merely concerns single parameter of pedestrian flow. Finally, an assessment framework for dynamic congestion risk at bottlenecks is suggested. With this framework, the change of congestion situations of a monitored region can be mastered through data-driven approach, and thus the transformation of normal flowing to congestion of the crowd can be quantified through probabilistic analysis.

Facile Fabrication of Quaternary Ammonium Salt Modified Cotton Linter by Radiation Grafting and its Effective Removal of Methyl Orange: Batch and Dynamic Flow Mode Studies

Jifu Du,Manman Zhang,Zhen Dong,Xin Yang,Houhua Xiong,Zhengkui Zeng,Zhiyuan Chen,Long Zhao 한국섬유공학회 2022 Fibers and polymers Vol.23 No.4

Methyl orange plays a vital role in various branches of the dyeing and textile industries and must be treated beforebeing discharged into the environment. In this study, methacryloxyethyltrimethyl ammonium chloride (DMC) functionalizedcotton linter (DMCCL) was prepared using a radiation technique. The prepared DMCCL was then characterized by IR, SEM,TG, and XPS analyses. The results showed that DMC was successfully grafted onto the surface of the cotton linter. Theadsorption performance toward methyl orange (MO) was investigated using batch and fix-bed column experiments. Adsorption kinetic and isotherm studies were well described by pseudo-second-order kinetic and Langmuir isotherm model,respectively. The maximum adsorption capacity for MO was 645.16 mg/g. The fixed-bed column experiment showed thatThomas and Yoon-Nelson models described the experimental data well. The column study showed the adsorption capacityreached 564.46 mg/g with a MO concentration of 25 mg/l and flow rate 1.5 ml/min. The saturated DMCCL column could beregenerated efficiently by eluting with 1 M HCl. Therefore, the DMCCL exhibited excellent adsorption performance, whichis suitable for MO removal from aqueous solution.

Surface Modification of Poly(vinylidene fluoride) Ultrafiltration Membranes with Chitosan for Anti-Fouling and Antibacterial Performance

Weiwei Xia,Manman Xie,Xia Feng,Li Chen,Yiping Zhao 한국고분자학회 2018 Macromolecular Research Vol.26 No.13

A graft copolymer (PVDF-g-PAA) having poly(vinylidene fluoride) (PVDF) backbones and poly(acrylic acid) (PAA) side chains was synthesized using the radical polymerization method and the PVDF-g-PAA copolymer membrane was prepared via immersion phase inversion. Then the chitosan was immobilized on the surface of the copolymer membrane by covalent bond. The morphology, surface chemical structure and performance of the modified membranes were characterized by scanning electron microscopy, attenuated total reflection-Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, water contact angle, permeation measurement, antifouling and antibacterial tests. The results showed that the contact angle of the modified membrane decreased, and the water flux increased from 37.74Lm-2h-1 for pure PVDF membrane to 119.43 Lm-2h-1, which indicated that the modified membrane had higher hydrophilicity than unmodified membrane. The modified membrane has better antifouling properties than pure PVDF membrane due to the increase of surface hydrophilicity, and the highest water flux recovery ratio can achieve 93.2%. Furthermore, the modified membrane showed good antibacterial activity (E. coli), and the maximum antibacterial ratio of the modified membrane was 89.6%.

Morphology, Thermal and Crystallization Properties of Polyamide-6/Boron Nitride (BN) Thermal Conductive Composites

Ru Xia,Manman Sun,Bin Yang,Jiasheng Qian,Peng Chen,Ming Cao,JIBIN MIAO,LIFEN SU 한국고분자학회 2018 폴리머 Vol.42 No.2

A series of the thermal conductive polyamide-6 (PA6) composites filled with boron nitride (BN) were prepared by two methods, including melting method (MM) and solution method (SM). The thermal conductivity, morphology, crystallization behavior, thermal stability, and rheological properties of PA6 composites were investigated. The results showed that the thermal conductivity of two methods increased with increase in the filler content, the thermal conductivity of PA6/BN composites containing 40 wt% BN prepared by melting method was up to 1.02W·m-1·K-1, while the thermal conductivity of PA6/BN composites prepared by solution method was up to 1.44 W·m-1·K-1 at the same filler content.

Nonlinear Control of Heterogeneous Vehicle Platoon with Time-varying Delays and Limited Communication Range

Haifeng Li,Zhenping Chen,Baochuan Fu,Manman Sun 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.6

Vehicle platooning can significantly increase throughput of transportation, while the impairment of communication may affect the control performance of vehicle platooning. Communication delays are inevitable in the process of driving, which will cause the instability of the platoon. Moreover, the transmission power level between vehicles is finite, resulting in a limited communication range. A nonlinear control algorithm is proposed where the car-following interactions between vehicles are considered. First, a third-order heterogeneous dynamic model is established for vehicles in the platoon. The control gains and parameters are heterogeneous. Then considering the constant time headway spacing policy and the gap supplement, conditions of the control gains for maintaining the internal stability of the platoon are obtained. Second, with time-varying communication delays taken into account, the allowed upper bound of communication delays is derived. Third, given the ability of each vehicle to receive information from multiple predecessors and followers, conditions of string stability are obtained, where the communication range is limited. Finally, numerical simulations are conducted to demonstrate the effectiveness of the proposed controller.