[en] This paper investigates the degradation of chlorobenzene by dielectric barrier discharge (DBD) coupled with MnO_x/γ-Al₂O₃ catalysts. MnO_x/γ-Al₂O₃ catalysts were prepared using the impregnation method and were characterized in detail by N₂ adsorption/desorption, x-ray diffraction and x-ray photoelectron spectroscopy. Compared with the single DBD reactor, the coupled reactor has a better performance on the removal rate of chlorobenzene, the selectivity of CO_x, and the inhibition of ozone production, especially at low discharge voltages. The degradation rate of chlorobenzene and selectivity of CO_x can reach 96.3% and 53.0%, respectively, at the specific energy density of 1350 J l^–1. Moreover, the ozone concentration produced by the discharge is significantly reduced because the MnO_x/Al₂O₃ catalysts contribute to the decomposition of ozone to form oxygen atoms for the oxidation of chlorobenzene. In addition, based on analysis of the byproducts, the decomposition mechanism of chlorobenzene in the coupled reactor is also discussed. (paper)

[en] A new combined reactor with Hg/Ar electrodeless ultraviolet (EDUV) activated by DBD for 3,4-dichlorodiphenyl ether abatement is presented. The effect of specific input energy and feeding gas component on 3,4-dichlorodiphenyl ether removal efficiency has been explored. Compared with a single DBD system, this new combined process performed a significant promotion on 3,4-dichlorodiphenyl ether abatement. Experiment results verified that active oxygen clearly contributed to the synergistic activity of DBD-EDUV system. Results of emission spectra showed that UV radiation of 253.7 nm could be detected in the DBD-EDUV system. Further, the products of DBD-EDUV process were analyzed via gas chromatography-mass spectrometer (GC-MS) to reveal involved decomposition mechanism. (paper)

[en] Although bidirectional motion on stairs can be commonly observed for external stairs and in some transportation facilities, a study that aims to investigate pedestrians’ walking characteristics under such conditions has never been conducted. In this paper, we perform a controlled experiment to study the bidirectional stair motion with varying flow ratios. It is found that on average, ascending pedestrians walk slower than those descending independent of the flow ratio. At the same density, the average velocity is the smallest for the full bidirectional flow when compared with those in the descending and ascending ones, indicating that the full bidirectional flow is not a simple combination of unidirectional pedestrians. According to the individual time to collision, congestion level and crowd danger, the run when the flow ratio is 0.5 can be considered to be the most critical with a large number of fierce conflicts. Thus, a balanced ascending and descending flow situation should be intentionally avoided for stairs where the bidirectional motion may occur. (paper: interdisciplinary statistical mechanics)

[en] In this paper, we introduce dyad social groups into the experiment to mimic uni- and bidirectional pedestrian flows that are closer to real life. According to the experimental videos, different strategies of collision avoidance for dyads are observed and classified. Moreover, we observe an interesting lane-merging phenomenon in bidirectional scenarios. Fundamental diagrams are calculated based on two measurement methods, and further compared with previous individual experiments (without dyads), confirming the negative impact of social groups due to their inherent cohesion during the movement process. Then, group characteristics such as group distance and spatial alignment are analyzed under the influence of different global densities. It is interesting to note that the effect of density on spatial alignment distribution is opposite in uni- and bidirectional scenarios, i.e. the increasing density will make the distribution less scattered in the unidirectional flow, which is contrary to the phenomenon in the bidirectional flow. Finally, based on the time evolution of congestion level and crowd danger, they can be good indicators of transitions from disorder to order, especially in bidirectional scenarios. Furthermore, the differences between uni- and bidirectional flows can be well distinguished through the relations between density and congestion level, as well as crowd danger. (paper)

[en] Highlights: • A model based on least effort principle was proposed to simulate heterogeneous pedestrian flow. • The model is validated with several experimental data on unidirectional pedestrian flow. • The influence of corridor width and velocity distribution of crowd on unidirectional heterogeneous pedestrian flow were analyzed. • Some quantitative results which are of practical importance in traffic facilities design were obtained. - Abstract: In the context of global aging, how to design traffic facilities for a population with a different age composition is of high importance. For this purpose, we propose a model based on the least effort principle to simulate heterogeneous pedestrian flow. In the model, the pedestrian is represented by a three-disc shaped agent. We add a new parameter to realize pedestrians' preference to avoid changing their direction of movement too quickly. The model is validated with numerous experimental data on unidirectional pedestrian flow. In addition, we investigate the influence of corridor width and velocity distribution of crowds on unidirectional heterogeneous pedestrian flow. The simulation results reflect that widening corridors could increase the specific flow for the crowd composed of two kinds of pedestrians with significantly different free velocities. Moreover, compared with a unified crowd, the crowd composed of pedestrians with great mobility differences requires a wider corridor to attain the same traffic efficiency. This study could be beneficial in providing a better understanding of heterogeneous pedestrian flow, and quantified outcomes could be applied in traffic facility design.