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.

Investigation of the Probability of a Safe Evacuation to Succeed in Subway Fire Emergencies Based on Bayesian Theory

Jinghong Wang,Wenyu Yan,Han Xu,Youran Zhi,Zhirong Wang,Juncheng Jiang 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.3

Emergency evacuation in subway fires is one of the hot issues in public safety. Based on Bayesian theory, a dynamic evacuation risk analysis model considering both psychological and behavioral responses of evacuees was proposed in this contribution. A subway fire scene was modeled using the Event Tree Analysis (ETA) according to the questionnaire survey at Nanjing Xinjiekou station. In this fire scenario, three control events (the fire alarm, the exhaust system and the evacuation route) were related to fire evacuation control and two control events (active escape and passive escape), which were specifically defined, were related to personnel characteristics. Subsequently, the probability of the final state of each scene was calculated by Monte Carlo simulation. Combined with the statistics of accidents and safe evacuation of subway fire cases from 1976 to 2013, the posterior probability distribution of safety evacuation was obtained after real-time dynamic updating of its precursor probability through Bayesian theory. Results show that the posterior probability of safety evacuation to succeed is around 0.8. This indicates that there is still a probability of 0.2 resulting in injury or fatalities in subway accidents even though most passengers are safely evacuated. It also suggests that utilization of 0.2 as the safety threshold would be an appropriate choice.

Evacuation of Nursing Home Based on Massmotion: Effect of the Distribution of Dependent Elderly

Jia Li,Jinghong Wang,Bowei Jin,Yan Wang,Youran Zhi,Zhirong Wang 대한토목학회 2020 KSCE Journal of Civil Engineering Vol.24 No.4

As dramatically increased elderly population, China is entering a society of deep aging. Due to the decline of physical functions, the elderly move slowly and have difficulty in escape. Hence, enough attention should be paid on pedestrian crowds’ evacuation in a nursing home. This paper takes Chinese old-age care institutions as the research object. Using the Massmotion based on the social force to establish the evacuation model and setting the parameters according to the movement characteristics of the elderly, this paper studied the influence of the dependent elderly on evacuation efficiency when they are distributed to the higher floors of the nursing home in different proportions. The results show that the evacuation time is significantly prolonged with the increase of the proportion of dependent elderly, and there is a controllable critical value for the proportion of dependent elderly. Aspeed-up phenomenon is observed when the old man enters the landing from the stairway, and meanwhile, with the increase of the proportion of dependent elderly, the acceleration position is gradually advanced, while the instantaneous speed declines. The results of this study can provide references in properly arranging the distribution of elderly accommodation and safe evacuation of the aged care institutions.

Flexible Voltage Support Control with Imbalance Mitigation Capability for Inverter-Based Distributed Generation Power Plants under Grid Faults

Wang, Yuewu,Yang, Ping,Xu, Zhirong The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.4

The high penetration level of inverter-based distributed generation (DG) power plants is challenging the low-voltage ride-through requirements, especially under unbalanced voltage sags. Recently, a flexible injection of both positive- (PS) and negative-sequence (NS) reactive currents has been suggested for the next generation of grid codes. This can enhance the ancillary services for voltage support at the point of common coupling (PCC). In light of this, considering distant grid faults that occur in a mainly inductive grid, this paper proposes a complete voltage support control scheme for the interface inverters of medium or high-rated DG power plants. The first contribution is the development of a reactive current reference generator combining PS and NS, with a feature to increase the PS voltage and simultaneously decrease the NS voltage, to mitigate voltage imbalance. The second contribution is the design of a voltage support control loop with two flexible PCC voltage set points, which can ensure continuous operation within the limits required in grid codes. In addition, a current saturation strategy is also considered for deep voltage sags to avoid overcurrent protection. Finally, simulation and experimental results are presented to validate the effectiveness of the proposed control scheme.

Proteolysis Characteristics of Sarcoplasmic, Myofibrillar, and Stromal Proteins Separated from Grass Carp and Antioxidant Properties of Their Hydrolysates

Haiyan Wang,Fenglan Zhang,Jin Cao,Qingsheng Zhang,Zhirong Chen 한국식품과학회 2013 Food Science and Biotechnology Vol.22 No.2

Proteolysis of grass carp sarcoplasmic, myofibrillar,and stromal proteins by 5 commercial proteases were studied. Sarcoplasmic and myofibrillar protein could be well hydrolyzed by Alcalase 2.4 L to reach high protein recoveries (PR) (71.86±2.46 and 80.77±3.05%, respectively),while the maximum PR for stromal protein was only 42.83±2.84%. However, stromal hydrolysates, containing mostly 6-10 kDa fraction, exhibited higher ·OH scavenging activities due to its high content of antioxidant-assisting amino acids. Alcalase 2.4 L and pancreatin 6.0, which produced hydrolysates with relative high degree of hydrolysis (DH), were used for further hydrolysis of whole grass carp protein with the assistance of response surface methodology (RSM). The results showed that serine proteases (Alcalase 2.4 L and pancreatin 6.0) could produce sarcoplasmic, myofibrillar, or stromal hydrolysates with relatively high PR, DH, and strong ·OH scavenging activity, which may be used to prepare antioxidant hydrolysates from grass carp.

Flexible Voltage Support Control with Imbalance Mitigation Capability for Inverter-Based Distributed Generation Power Plants under Grid Faults

Yuewu Wang,Ping Yang,Zhirong Xu 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.4

The high penetration level of inverter-based distributed generation (DG) power plants is challenging the low-voltage ride-through requirements, especially under unbalanced voltage sags. Recently, a flexible injection of both positive- (PS) and negative-sequence (NS) reactive currents has been suggested for the next generation of grid codes. This can enhance the ancillary services for voltage support at the point of common coupling (PCC). In light of this, considering distant grid faults that occur in a mainly inductive grid, this paper proposes a complete voltage support control scheme for the interface inverters of medium or high-rated DG power plants. The first contribution is the development of a reactive current reference generator combining PS and NS, with a feature to increase the PS voltage and simultaneously decrease the NS voltage, to mitigate voltage imbalance. The second contribution is the design of a voltage support control loop with two flexible PCC voltage set points, which can ensure continuous operation within the limits required in grid codes. In addition, a current saturation strategy is also considered for deep voltage sags to avoid overcurrent protection. Finally, simulation and experimental results are presented to validate the effectiveness of the proposed control scheme.

Mathematical programming model of process plant safety layout using the equipment vulnerability index

Liping Guo,Zhirong Wang,Pinkun Guo,Jinghong Wang,Dan Zhao 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.4

Safety is the focus of attention in plant layout problems. Previous studies have often expressed safety as a cost of risk, that is, the cost of property losses that may occur in an accident. In this paper, the influence of uncertainty on the equipment vulnerability is quantitatively considered and a more reliable process plant layout is proposed. The equipment vulnerability index is used to evaluate the vulnerability level of the target equipment in case of an accident, which is applied to propose a mixed-integer nonlinear optimized process plant layout to minimize domino risk. In addition, a decision matrix is applied to determine whether the risk level of the optimized layout of the target equipment is acceptable. Damage probability and vulnerability are the basic inputs of this matrix. The proposed method was applied to a coal-water slurry gasification process and the results show that the layout obtained by the proposed model has better practical value than the current layout, reducing the domino risk by 53.2%. Meanwhile, the model can be used to identify critical equipment and select targeted safety measures during the production stage.

1-Aminocyclopropane-1-Carboxylate Deaminase from Pseudomonas stutzeri A1501 Facilitates the Growth of Rice in the Presence of Salt or Heavy Metals

( Yunlei Han ),( Rui Wang ),( Zhirong Yang ),( Yuhua Zhan ),( Yao Ma ),( Shuzhen Ping ),( Liwen Zhang ),( Min Lin ),( Yongliang Yan ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.7

1-Aminocyclopropane-1-carboxylate (ACC) deaminase, which is encoded by some bacteria, can reduce the amount of ethylene, a root elongation inhibitor, and stimulate the growth of plants under various environmental stresses. The presence of ACC deaminase activity and the regulation of ACC in several rhizospheric bacteria have been reported. The nitrogen-fixing Pseudomonas stutzeri A1501 is capable of endophytic association with rice plants and promotes the growth of rice. However, the functional identification of ACC deaminase has not been performed. In this study, the proposed effect of ACC deaminase in P. stutzeri A1501 was investigated. Genome mining showed that P. stutzeri A1501 carries a single gene encodingACC deaminase, designated acdS. The acdS mutant was devoid of ACC deaminase activity and was less resistant to NaCl and NiCl2 compared with the wild-type. Furthermore, inactivation of acdS greatly impaired its nitrogenase activity under salt stress conditions. It was also observed that mutation of the acdS gene led to loss of the ability to promote the growth of rice under salt or heavy metal stress. Taken together, this study illustrates the essential role of ACC deaminase, not only in enhancing the salt or heavy metal tolerance of bacteria but also in improving the growth of plants, and provides a theoretical basis for studying the interaction between plant growth-promoting rhizobacteria and plants.

Impact of NR1I2, adenosine triphosphate-binding cassette transporters genetic polymorphisms on the pharmacokinetics of ginsenoside compound K in healthy Chinese volunteers

Zhou, Luping,Chen, Lulu,Wang, Yaqin,Huang, Jie,Yang, Guoping,Tan, Zhirong,Wang, Yicheng,Liao, Jianwei,Zhou, Gan,Hu, Kai,Li, Zhenyu,Ouyang, Dongsheng The Korean Society of Ginseng 2019 Journal of Ginseng Research Vol.43 No.3

Background: Ginsenoside compound K (CK) is a promising drug candidate for rheumatoid arthritis. This study examined the impact of polymorphisms in NR1I2, adenosine triphosphate-binding cassette (ABC) transporter genes on the pharmacokinetics of CK in healthy Chinese individuals. Methods: Forty-two targeted variants in seven genes were genotyped in 54 participants using Sequenom MassARRAY system to investigate their association with major pharmacokinetic parameters of CK and its metabolite 20(S)-protopanaxadiol (PPD). Subsequently, molecular docking was simulated using the AutoDock Vina program. Results: ABCC4 rs1751034 TT and rs1189437 TT were associated with increased exposure of CK and decreased exposure of 20(S)-PPD, whereas CFTR rs4148688 heterozygous carriers had the lowest maximum concentration ($C_{max}$) of CK. The area under the curve from zero to the time of the last quantifiable concentration ($AUC_{last}$) of CK was decreased in NR1I2 rs1464602 and rs2472682 homozygous carriers, while $C_{max}$ was significantly reduced only in rs2472682. ABCC4 rs1151471 and CFTR rs2283054 influenced the pharmacokinetics of 20(S)-PPD. In addition, several variations in ABCC2, ABCC4, CFTR, and NR1I2 had minor effects on the pharmacokinetics of CK. Quality of the best homology model of multidrug resistance protein 4 (MRP4) was assessed, and the ligand interaction plot showed the mode of interaction of CK with different MRP4 residues. Conlusion: ABCC4 rs1751034 and rs1189437 affected the pharmacokinetics of both CK and 20(S)-PPD. NR1I2 rs1464602 and rs2472682 were only associated with the pharmacokinetics of CK. Thus, these hereditary variances could partly explain the interindividual differences in the pharmacokinetics of CK.

Preparation and Characterization of a Novel pH-Sensitive Coated Microsphere for Duodenum-Specific Drug Delivery

Dan Zhou,Yuan Huang,Xi Zhu,Yang Wang,Yun Jin,Xuefan Xu,Tingting Fan,Yan Liu,Zhirong Zhang 대한약학회 2012 Archives of Pharmacal Research Vol.35 No.5

The aim of this study is to develop a duodenum-specific drug delivery system on the basis of a pH-sensitive coating and a mucoadhesive inner core for eradication of Helicobacter pylori (H. pylori) in the ulcer duodenum. Hydroxypropyl methylcellulose acetate maleate (HPMCAM) was used as the pH-sensitive material, which dissolves around pH 3.0. The mucoadhesive microspheres loaded with furazolidone (FZD-ad-MS) were prepared by the emulsification-solvent evaporation method using Carbopol 971NP as the mucoadhesive polymer. The prepared pH-sensitive coated mucoadhesive microspheres (AM-coated-MS) were characterized in regards to particle size, drug loading efficiency, morphological change, drug stability, drug release and in vitro anti-H. pylori activity. The particle size was 160.97 ± 47.24 μm and 336.44 ± 129.34 μm, and the drug content was 42.33 ± 3.43% and 10.96 ± 1.29% for FZD-ad-MS and AM-coated-MS, respectively. The morphological changes in different pH media were characterized by scanning electron microscopy (SEM). HPMCAM coating improved the stability of the FZD-ad-MS and these particles were expected to remain intact until their arrival in the duodenum. The drug release was extremely suppressed at pH 1.2 for AM-coated-MS, but increased at pH 4.0 after regeneration of FZD-ad-MS. In addition, FZD-ad-MS exhibited excellent anti-H. pylori activity in vitro. Thus, the HPMCAM-coated microspheres developed in this study hold great promise for use as a duodenum-specific drug delivery system for H. pylori clearance.