Simulation and Optimization of Pedestrian Regular Evacuation in Comprehensive Rail Transit Hub – A Case Study in Beijing

Extensive efforts have been made in pedestrian evacuation of urban rail transit systems, since there has emerged an increasing number of congestion problems. However, few studies focus on the comprehensive urban rail transit hubs. As a comprehensive interchange hub integrating urban railway and intercity railway lines, Beijing West Railway Station was taken as a case study object. The pedestrian evacuation characteristics were analysed first. Then, a social force-based simulation model of Beijing West Railway Station was constructed in PTV Viswalk. The model was applied to visually display a real evacuation process and help identify evacuation bottlenecks. The results showed that the risk points at different facilities had various causes and features. Furthermore, the simulation model could also be used to evaluate the effectiveness of different optimization measures as long as certain model parameters were changed beforehand.</p

Analysis and application of safety risks for gas pipelines in karst sinkhole-prone areas based on the D/I-MICMAC-VS integrated method

To mitigate the risk of gas pipelines in karst sinkhole-prone areas, this study employs the DEMATEL/ISM method to elucidate the hierarchical structure and causal relationships among various factors in the system, considering four categories of accident causes: human, material, environment and management. Additionally, the MICMAC method is utilized to analyze the dependence and driving force of risk factors. Utilizing the Visual Studio platform, the software for risk analysis of gas pipelines in karst sinkhole-prone areas is developed. This research introduces the D/I-MICMAC-VS integrated risk analysis method and provides an example analysis. The results demonstrate that: (1) The risk factors for gas pipelines in karst sinkhole-prone areas are distributed across six levels. The possibility of risk accidents can be reduced in the short term by rigorously managing surface-level direct factors, while middle-level indirect factors play an intermediary role in the system. Effective control of gas pipeline accidents can only be achieved by addressing deep-rooted factors fundamentally. (2) The spontaneous cluster serves as a key element for risk management and control of gas pipeline accidents, and prioritized intervention significantly aids in accident prevention. The independent cluster directly influences the system’s risk level through its own changes and development. The linkage cluster plays a pivotal role in transmitting and promoting the evolution and development of accidents. Effective risk management and control can be achieved by discerning the deep root factors that inducing changes in the dependency cluster

Data Extraction via Semantic Regular Expression Synthesis

Many data extraction tasks of practical relevance require not only syntactic pattern matching but also semantic reasoning about the content of the underlying text. While regular expressions are very well suited for tasks that require only syntactic pattern matching, they fall short for data extraction tasks that involve both a syntactic and semantic component. To address this issue, we introduce semantic regexes, a generalization of regular expressions that facilitates combined syntactic and semantic reasoning about textual data. We also propose a novel learning algorithm that can synthesize semantic regexes from a small number of positive and negative examples. Our proposed learning algorithm uses a combination of neural sketch generation and compositional type-directed synthesis for fast and effective generalization from a small number of examples. We have implemented these ideas in a new tool called Smore and evaluated it on representative data extraction tasks involving several textual datasets. Our evaluation shows that semantic regexes can better support complex data extraction tasks than standard regular expressions and that our learning algorithm significantly outperforms existing tools, including state-of-the-art neural networks and program synthesis tools

Bose condensation of upper-branch exciton-polaritons in a transferrable microcavity

Exciton-polaritons are composite bosonic quasiparticles arising from the strong coupling of excitonic transitions and optical modes. Exciton-polaritons have triggered wide exploration in the past decades not only due to their rich quantum phenomena such as superfluidity, superconductivity and quantized vortices but also due to their potential applications for unconventional coherent light sources and all-optical control elements. Here, we report the observation of Bose-Einstein condensation of the upper polariton branch in a transferrable WS$_2$ monolayer microcavity. Near the condensation threshold, we observe a nonlinear increase in upper polariton intensity. This sharp increase in intensity is accompanied by a decrease of the linewidth and an increase of the upper polariton temporal coherence, all of which are hallmarks of Bose-Einstein condensation. By simulating the quantum Boltzmann equation, we show that the upper polariton condensation only occurs for a particular range of particle density. We can attribute the creation of Bose condensation of the upper polariton to the following requirements: 1) the upper polariton is more excitonic than the lower one; 2) there is relatively more pumping in the upper branch; and 3) the conversion time from the upper to the lower polariton branch is long compared to the lifetime of the upper polaritons

Reconfigurable thermo-optic polymer switch based true-time-delay network utilizing imprinting and inkjet printing

Abstract: Reconfigurable true-time-delay lines, comprising of 2x2 thermo-optic polymer switches and rib waveguides are fabricated utilizing a combination of roll-to-roll (R2R) compatible UV imprinting and ink-jet printing, which promises high throughput and low cost photonic devices