Experimental study and numerical simulation of evacuation from a dormitory

In this paper, a visual servoing approach is developed for the trajectory tracking control and depth estimation problem of a mobile robot without a priori knowledge about desired velocities. By exploiting the multiple images captured by the on-board camera, the current and desired poses (i.e., scaled translation and orientation) of the mobile robot are reconstructed to define system errors. Then, an adaptive time-varying controller is proposed to achieve the trajectory tracking task in the presence of nonholonomic constraint and unknown depth parameters. Most of previous works require the measurement of the desired velocity information to facilitate the controller design, leading to tedious offline computation. In this paper, to eliminate this requirement, the desired velocities are estimated in real-time based on a reduced order observer. Moreover, an augmented update law is designed to compensate for the unknown depth parameters and identify the inverse depth constant. The Lyapunov-based method is employed to prove that the proposed controller achieves asymptotic tracking, and the inverse depth estimate converges to its actual value provided that a persistent excitation condition is satisfied. Subsequently, a robust data-driven algorithm is introduced to ensure the convergence of the inverse depth estimate under a relaxed finite excitation condition. Simulation and experimental results are provided to demonstrate the effectiveness of the proposed approach.

Simulating pedestrian flow through narrow exits

An agent-based modeling approach to collaborative classrooms evacuation process

Developing a database for emergency evacuation model

Large scale disasters often create the need for evacuating affected regions to save lives. Disaster management authorities need evacuation simulation tools to assess the efficiency of various evacuation scenarios and the impact of a variety of environmental and social factors on the evacuation process. Therefore, sound simulation models should include the relevant factors influencing the evacuation process. More specifically, to be reliable in critical situations, evacuation simulations must integrate information on time-varying phenomena that can affect the evacuation process, such as the impact of meteorological conditions, road incidents, or other relevant events. Sensor networks constitute an efficient solution for gathering data on such events and feeding the evacuation simulation. However, the coupling of sensors with multi-agent simulation tools is not straightforward. In this chapter, we present a publish/subscribe system based on Event Calculus to support real-time multi-agent evacuation simulations. The system identifies relevant events from sensor data gathered through a Sensor Event Service that implements the OGC SWE standards and the Event Pattern Markup Language (EML). Then, the publish/subscribe system acts as a middleware between the Sensor data publishers and the multi-agent evacuation simulation through a Sensor Processing Service based on Event Calculus that infers the impact of events on the characteristics of the road network. The result is an evacuation simulation that can be deployed to assess various evacuation scenarios in real-time, during the crisis response.

Regional evacuation modeling for toxic-cloud releases and its application in strategy assessment of evacuation warning

Exit selection and pedestrian movement in a room with two exits under fire emergency

Elevator evacuation has been considered in high-rise building evacuation in the world, especially in China. Elevator safety has been widely studied for this purpose and technical standards are also available in different countries. However, it is critical to understand human behaviors in elevator evacuation before elevators can be used in building evacuation. It is expected that social relation (family, friend, classmate, etc.) will play an important role on evacuation behaviors. However, researches are largely missing on social relation and its impacts on movement and behaviors of the evacuees. This paper aims to investigate the crowd evacuation considering social relation. An evacuation experiment is conducted in a 11-storey office building. Participants who take part in the experiment include individuals, families and lovers. Evacuation behaviors especially decision-making as well as important factors affecting evacuees’ choices are discussed. Movement characteristics of evacuees in the stair are also analyzed. It is concluded that family members will take actions, such as take elevators or stairs, together. Females and evacuees in poor condition prefer to take the elevator during evacuation. Many pairs or small groups may be formed owing to social relations. The groups take more time to make decision. The members in small groups may block the traffic and slow down the speed of the crowd. Evacuation efficiency changes greatly considering small group behaviors and social relations. Experimental results are helpful for determining the effective rules and regulations in elevator evacuation in high-rise buildings.

Micromechanical aspects of failure in unidirectional fiber reinforced composites are investigated using combined experimental and analytical methods. Results from an experimental investigation on mechanical behavior of a unidirectional fiber reinforced polymer composite (E-glass/vinylester) with 50% fiber volume fraction under quasi-static uniaxial and proportional multiaxial compression are presented. Detailed examination of the specimen during and after the test reveals the failure mode transition from axial splitting to kink band formation as the loading condition changes from uniaxial to multiaxial compression. Motivated by the experimental observations, an energy-based model is developed to provide an analytical estimate of the critical stress for axial splitting observed in unidirectional fiber reinforced composites under uniaxial compression in the fiber direction (also with weak lateral confinement). The analytic estimate for the compressive strength is used to illustrate its dependence on material properties, surface energy, fiber volume fraction, fiber diameter and lateral confining pressure. To understand the effect of flaws on the strength of unidirectional fiber reinforced composites, a fracture mechanics based model for failure is developed. Based on this model, failure envelope, dominant initial flaw orientation and failure mode for the composites under a wide range of stress states are predicted. Parametric study provides quantitative evaluation of the effect of various mechanical and physical properties on failure behavior and identifies their influence on strength. Finally, results from an experimental investigation on the dynamic mechanical behavior of unidirectional E-glass/vinylester composites with 30%, 50% fiber volume fraction under uniaxial compression are presented. Limited experimental results are also presented for the 50% fiber volume fraction composite under dynamic proportional lateral confinement. Specimens are loaded in the fiber direction using a modified Kolsky (split Hopkinson) pressure bar. The results indicate that the compressive strength of the composite increases with increasing strain rate and confinement. Post-test scanning electron microscopy reveals that axial splitting is the dominant failure mechanism in the composites under uniaxial compression in the entire range of strain rates. Based on the experimental results and observations, the energy-based analytic model is extended to predict the compressive strength of these composites under dynamic uniaxial loading conditions.

We propose a new concept,“inflow process” of pedestrians as a counterpart of an evacuation process. In the inflow process, pedestrians enter a limited area without hurrying. This type of pedestrian motion can be observed in our daily life, e.g. in elevators, trains, etc. From experimental observation, we found intriguing behaviors, including pedestrians’ preference for boundaries, collective orientation, etc. Besides, the inflow process has contrastive aspects to evacuation process. For this reason the process is important for the pedestrian dynamics field.

In this paper, we study how seriously the exit quantity, personnel distribution, and safety evacuation guidance affect the evacuation in a six-story low-rise building environment through the Pathfinder simulation model. In particular, we analyze the evacuation process, evacuation times, and the congestion of four different scenes. According to our experimental results, the current situation of the dormitory delays the evacuation process by causing congestion and blocking phenomenon significantly. The optimized situation (two safety exits, the optimized personnel distribution, and safety evacuation guidance) can improve serious congestion and blocking significantly. The specific theoretical and practical implications of the result will also lead emergency administrators to pay more attention to security settings and management behavior in order to improve the evacuation efficiency.

s The evacuation process in buildings provides an efficient method for engineers to evaluate the rationality of the architectural design and structural design scheme. The simulation of the authentic evacuation process is conducive to accurately evaluate the casualties of buildings under earthquake. The economic loss estimation in the performance-based seismic design method can then be implemented. This study improves the traditional cellular automata model in order to simulate the crowd evacuation process in buildings under earthquake. The modified model simulates the attraction of exits to crowds, herd behavior of crowds, avoidance behavior for obstacles, decision-making behavior for paths/exits selection, and conflict between pedestrians in the evacuation process. Based on the variation coefficient of evacuation time and video which records authentic evacuation under earthquake, the influence coefficients of each factors are determined. In addition, the modified cellular automata model uses the refined cellular space to describe the geometric dimensions of the evacuation environments and obstacles, and therefore it improves the accuracy of the evacuation model. The explicit finite element method is used to simulate the seismic damage process of structural and non-structural components. The judgment criterion of casualties which combines the finite element model with the evacuation model, is proposed. The number and distribution of casualties are predicted based on the criteria. The prediction method for casualties helps the architects to optimize the size and layout of the building components. In the structural design stage, identifying areas with high population density or high casualties is conducive to optimize the structural design scheme, and provide a basis for the formulation of a post-earthquake rescue plan. Finally, a seven-story official building with reinforced concrete frame structure located in Dujiangyan City, Sichuan Province, China is considered as example to verify the rationality and applicability of the proposed method.

As disasters, both natural and human-induced, grow more frequent, effective sheltering and evacuation become crucial. While existing studies considered approaches optimizing shelter location by simulating individuals’ evacuation behaviors, most rely on pre-determined functions and overlook the heterogeneity of individuals’ behaviors. To address this limitation and account for the complexities of residents’ evacuation processes, we develop an approach that integrates Agent Based Modeling (ABM) with a Genetic Algorithm (GA), using the evacuation simulation results from ABM to optimize community shelter locations. We validate the proposed method by simulating residents’ evacuation in an assumed nighttime earthquake event within a student residential community in Shenzhen. This study provides a tool assisting in the optimization of community shelter locations in pre-disaster planning.

Masonry systems have been used extensively in historical, commercial, and residential buildings. A large number of experimental and computational studies have been conducted to investigate the behavior of masonry components and systems, including mortar, units (e.g., blocks), and walls. The Discrete Element Method (DEM) has been used to analyze masonry systems with a macro modeling methodology (i.e., structural systems like walls). Masonry systems and their components have not been analyzed using a micro-modeling methodology with the DEM. The objective of this paper is the deterministic calibration of micro-parameters of the mortar cylinder model based on a computationally efficient DEM model. To achieve this objective, a parametric analysis is introduced through a series of models of a mortar specimen tested under simple compression to explore the impact of the model micro-parameters when trying to reproduce a set of experimental observations conducted at the Universidad Autonoma de Yucatan Mexico (UADY). A calibration process based on optimization is implemented to determine the best estimates of the model’s micro-parameters. This paper is divided into three analyses. First, the particle size distribution of the mortar’s aggregate is used as a reference (i.e., scale 1), and then up-scaled 1.5 and two times using four particle sizes; second, using the two-times scaled particle size, the influence of varying particle sizes within a reference particle size distribution was explored (from one particle size to 4 particle sizes following the aggregate particle size distribution); and third, a parametric analysis is performed varying seven micro-parameters, one at the time, varying from 0.25 to 1.5, at 0.25 scale increments, on a model including four particle sizes. The results show micro-parameters and stress-strain curves of mortar for the different analyses, and a representation of the cross sections of the models, indicating the distributions of contact forces. All proposed models showed good agreement with the experimental observations (i.e., stress-strain curve). Also, it was observed from the proposed analyses that some micro-parameters vary as the particle size and the scaled particle size distributions change when using the same experimental stress-strain curve. Also, it was found that the proposed DEM must contain at least two particle sizes to significantly improve the particle interlocking to ensure that the mechanistic behavior reproduces the same experimental observations. Finally, from the results presented in this work, it is concluded that it is possible to produce a computationally efficient model that can later serve as a reference for future research accounting for other control variables such as particle shape, particle size distributions, the exploration of damage propagation effects, and most importantly their corresponding uncertainty quantification and propagation effects in masonry systems.

To construct an appropriate motor command from signals that provide a representation of desired action, the nervous system must take into account the dynamic characteristics of the motor plant to be controlled. In the oculomotor system, signals specifying desired eye velocity are thought to be transformed into motor commands by an inverse dynamic model of the eye plant that is shared for all types of eye movements and implemented by a weighted combination of eye velocity and position signals. Neurons in the prepositus hypoglossi and adjacent medial vestibular nuclei (PH-BT neurons) were traditionally thought to encode the "eye position" component of this inverse model. However, not only are PH-BT responses inconsistent with this theoretical role, but compensatory eye movement responses to translation do not show evidence for processing by a common inverse dynamic model. Prompted by these discrepancies between theoretical notions and experimental observations, we reevaluated these concepts using multiple-frequency rotational and translational head movements. Compatible with the notion of a common inverse model, we show that PH-BT responses are unique among all premotor cell types in bearing a consistent relationship to the motor output during eye movements driven by different sensory stimuli. However, because their responses are dynamically identical to those of motoneurons, PH-BT neurons do not simply represent an internal component of the inverse model, but rather its output. They encode and distribute an estimate of the motor command, a signal critical for accurate motor execution and learning.