Simulation of pedestrian counter flow with conflicting preference using a lattice-based simulation model

2020 ◽  
Vol 31 (09) ◽  
pp. 2050120
Author(s):  
Kongjin Zhu ◽  
Jun Wang ◽  
Ning Guo ◽  
Zhongjun Ding ◽  
Peng Mei

Pedestrian counter flows widely exist in public pedestrian facilities such as corridors, sidewalks, signalized crossings and so on. There is one specific flow in real life, namely counter flow with conflicting walking preference which often occurs in the case of presence of one-sidedly asymmetry due to shadows, light, snow and so on. It is often overlooked in practice and the related studies are still limited. In this study, to better understand the flow dynamics of pedestrian flow with various walking preference, a simple lattice-based model was proposed in which position exchange and walking preference were simultaneously considered. Specifically, simulations including pedestrian counter flow with preference (Case A), with conflicting preference (Case B), and without preference (Basic case) were performed. Results show that the presented model can capture some essential features of pedestrian counter flow with various walking preference. It is not always necessary to intervene the behavior of pedestrians ’ conflicting preference, since appropriate degree of preference is sometimes beneficial to movement of pedestrians. In addition, with the significant influence of position exchange, the flow in Case A with more orderly motion is more efficient in the context of low density, while the flow in Case B with more frequent interactions is more efficient in the case of high density. The findings in this study will be helpful in crowd management as well as the design and operation of pedestrian facilities.

2012 ◽  
Vol 463-464 ◽  
pp. 189-193
Author(s):  
Kong Zhai Li ◽  
Masaaki Haneda ◽  
Masakuni Ozawa

Maghemite (γ-FeSubscript text2OSubscript text3) and hematite (α-Fe2O3) nanoparticles with various dominant exposure crystal planes were prepared by several different methods. The structure and the reducibility of these materials were investigated by XRD, Raman and H2-TPR technologies, and their catalytic performance for propene oxidation was also discussed. The maghemite (γ-FeSubscript text2OSubscript text3) showed a better reducibility than hematite (α-FeSubscript text2OSubscript text3), but its activity for propene oxidation is relatively lower. The exposure crystal plane of hematite has a significant influence on its catalytic activity for propene oxidation. Among the prepared four samples, the hematite-1 sample showed the best activity. The selective growth of any planes with a relative low density of Fe atoms for the α-FeSubscript text2OSubscript text3 catalyst would lead to an obvious decrease in the catalytic activity.


2017 ◽  
Vol 14 (2) ◽  
pp. 115 ◽  
Author(s):  
Khaled AlZebdeh ◽  
M. M. Nassar ◽  
M.A. Al-Hadhrami ◽  
O. Al-Aamri ◽  
S. Al-Defaai ◽  
...  

In recent decades, natural fibers have received attention of scientists and researchers due to their ecofriendly characteristics that qualify them as potential reinforcement in polymer composites in place of synthetic fibers.  In this study, an experimental investigation has been conducted to evaluate the effect of orientation of fibers on mechanical properties of a newly developed bio-composite in which date palm fronds (DPF) are embedded as fibers in low-density polyethylene (LDPE) matrix. Three bio-composite sheets with orientations of 0°, 45° and 90°, respectively have been fabricated after the date palm fronds were chemically treated. The fabricated composite specimens are tested under tensile load using Universal Testing Machine (UTM) in accordance with the ASTM D-638 standard. Then, a comparison of the experimental results against analytical results is made to examine the accuracy and agreement between the two. An inconsistency in moduli, as was discovered, is attributed to the adhesion quality between the fibers and surrounding matrix. Output results help to assess the applicability of such class of bio-composites in real-life applications.  The results of tensile strength, Young’s modulus, and elongation at break revealed that date palm fronds can be used as reinforcement material in polymer-based composites for low strength applications.  


2019 ◽  
Author(s):  
Syed Shah Zaman Haider Naqvi ◽  
Saber imani ◽  
Hossein Hosseinifard ◽  
M. Naveed Shahzad ◽  
Iqra Ijaz ◽  
...  

Abstract Background: Compositional abnormalities in lipoproteins and cardiovascular risk factors play an important role in the progression of diabetic peripheral neuropathy (DPN). This systematic review aimed to estimate the predicting value of low-density lipoprotein (LDL) and systolic blood pressure (SBP) level in type-2 diabetes mellitus (T2DM) patients with and without peripheral neuropathy. We also tried to determine whether LDL and SBP are associated with an increased collision risk of DPN. Materials and Methods: A systematic search was conducted for eligible publications which explored the LDL and SBP level in T2DM patients with and without peripheral neuropathy. The quality of the included studies was assessed by the QUADAS-2 tool. The standardized mean difference (SMD) with 95% CI of LDL and SBP level were pooled to assess the correlation between LDL and SBP level with DPN. We performed random effects meta-regression analyses to investigate factors associated with an increased collision risk of DPN. Results: There was a significant association between LDL and SBP with poor prognosis of DPN in those included studies (I2 = 88.1% and I2 = 84.9%, respectively, Both P < 0.001). European T2DM patients have higher serum level of LDL in compare with the European DPN patients (SMD = 0.16, 95 % CI: -0.06 - 0.38; P < 0.001). SBP level was associated with a 2.6 fold reduce in non-DPN patients of T2DM (SMD = -2.63, 95% CI: -4.00 - -1.27, P < 0.001). Furthermore, the results of the case-control study design model are more precise to show the accuracy of SBP in Asian T2DM patients. Old age European T2DM patients have significantly low collision risk in the last 30 years for diabetes drivers that indicates that LDL and SBP levels could be a promising vulnerability biomarker for early detection and effective intervention of DPN in real-life clinical practice of individuals with T2DM. Conclusion: Our finding supports the LDL and SBP status could be a promising prognostic biomarker for early detection and effective intervention of DPN in real-life clinical practice of individuals with T2DM.


Open Physics ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 77-85
Author(s):  
Haitao Lian ◽  
Yike Hu ◽  
R.D. Rohmat Saedudin

Abstract The relationship between the factors of formation mechanism of stratification and the pedestrian ratio in low-density state has not been analyzed by the existing human flow evacuation simulation method, so that the simulation effect is poor. Thus, the evacuation simulation method for different flow ratios in low-density state is proposed to analyze the walking characteristics of the opposite pedestrians. On the basis of the random deviation grid gas model, the view field of pedestrian is introduced as one parameter. Considering the preference characteristics of pedestrians for the movement of open areas within the view field, the improved random deviation grid gas model is constructed. Through the model, the stratification characteristics of the opposite pedestrian flow in the simple channel scene are simulated. The results show that the proposed method can reproduce the characteristics of non-layering phenomenon of opposite pedestrian flow in low-density state. According to the probability of layer formation, the density of the opposite pedestrian flow is divided into five intervals. The opposite pedestrian flow in the critical density region is metastable, and is susceptible to interference. These results are consistent with the dynamic evolution of the actual opposite pedestrian flow.


2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Dawei Zhang ◽  
Haitao Zhu ◽  
Shi Qiu ◽  
Boyan Wang

The avoidance behavior of pedestrians was characterized in the present paper by simulating the movement of crowds in both unidirectional and bidirectional pedestrian flow. A phase change of alternative lane formation observed in real bidirectional pedestrian flows has been studied, where pedestrians tended to evade individuals in counterflow and simultaneously keep a certain distance from each other in the uniform pedestrian flow when the counterflow disappeared. What is more, the comparison between the effect of evading and pushing behavior on evacuation has been investigated in the room egress scenario. Additionally, the evading and overtaking behavior of fast pedestrians have also been simulated in heterogeneous crowds. The performance of the proposed model was compared to the experimental data and the results obtained using other evacuation models. Numerical results showed that both the phase change of alternative lane formation in bidirectional pedestrian flow and the effective evading behavior in unidirectional pedestrian flow were conductive to reduce the evacuation time of pedestrian crowds. Even though pushing behavior of fast pedestrians seemed to improve the flow through the wide exit, it might lead to the panic and other negative effect on the crowds, such as crowds trample. The proposed model in this paper could provide a theoretical basis for the pedestrian crowd management during emergency evacuation.


2013 ◽  
Vol 24 (06) ◽  
pp. 1350037 ◽  
Author(s):  
BIAO LENG ◽  
JIANYUAN WANG ◽  
XIAOXI ZHAO ◽  
JUN FANG ◽  
ZHANG XIONG

The floor field (FF) model, up until now, has been the most widely used simulation in pedestrian flow dynamics for simple based scenarios. This paper presents an improvement on and upon the local view FF model by simulating pedestrian flow in more complex scenarios with typical goals and obstacles that may block or assist the sight of the pedestrian. In addition this model will also provide a detailed analysis entailing the simulation of multi-goal selections. This involves the visibility information on each cell being set, and a dynamic priority list of goals for every pedestrian being updated as he/she moves. The pedestrians select the convenient goal according to the priority of goals, the distances to the candidate goals and the degree of congestion. To aid in the theory of this and to make a better understanding of reality, a simulation scenario is conducted on a virtual MTR station, where parameter settings are discussed and some regular phenomena helpful to the designers of stations is put forward.


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