Modeling pedestrian evacuation movement in a swaying ship

With the advance in living standard, cruise travel has been rapidly expanding around the world in recent years. The transportation of passengers in water has also made a rapid development. It is expected that ships will be more and more widely used. Unfortunately, ship disasters occurred in these years caused serious losses. It raised the concern on effectiveness of passenger evacuation on ships. The present study thus focuses on pedestrian evacuation features on ships. On ships, passenger movements are affected by the periodical water motion and thus are quite different from the characteristic when walking on static horizontal floor. Taking into consideration of this special feature, an agent-based pedestrian model is formulized and the effect of ship swaying on pedestrian evacuation efficiency is investigated. Results indicated that the proposed model can be used to quantify the special evacuation process on ships.Comment: Traffic and Granular Flow'15, At Delft, the Netherland

A Shannon entropy approach for structural damage identification based on self-powered sensor data

© 2019 Elsevier Ltd Piezo-floating-gate (PFG) sensors are a class of self-powered sensors fabricated using piezoelectric transducers and p-channel floating-gate metal-oxide-semiconductor (pMOS) transistors. These sensors are equipped with a series of floating-gates that are triggered when the voltage generated by the piezoelectric transducers exceeds one of the specified thresholds. Upon activation, the floating-gates cumulatively store the duration of the applied strain events. Defining optimal voltage thresholds plays a key role in the efficiency of the PFG sensors for structural damage identification. In this paper, symbolic dynamic analysis (SDA) based on Shannon entropy is used to find the effective voltage thresholds that ensure the maximum detectability of the structural damage-related changes. To this end, a baseline is constructed using the strain data obtained from the undamaged structure. These data are used to set the voltage threshold on every floating gate of the sensor. Then the posterior state of the structure is monitored using thresholds set up on the baseline and a cumulative density function (CDF) of strain events. In order to determine the damage severity, a damage index is defined based on the Euclidean norm of the distance between the CDFs for the damaged and healthy structure. The proposed technique is verified using experimental data for a steel plate subjected to an in-plane tension loading. The results confirm the capability of the proposed method in monitoring structures for damage initiation and/or propagation using the PFG sensors, and the CDFs on which the damage sensitive feature (DSF) is based can provide additional insights into the stress distributions

Developing long-term monitoring of natural areas for a Unesco world heritage site: study case of la Reunion

La Réunion island, in the Mascarenes, has been recognized as a World Heritage site for its Piton, Cirques and Remparts since 2010. The site, coinciding with the core zone of La Réunion National Park, represents 100000 ha, equivalent to 40 % of the island. These dramatic landscapes of rugged terrain, impressive escarpments, forested gorges are dominated by three cliff-rimmed cirques and two volcanoes ― a dormant massif forming the highest peak, Piton des Neiges (3069 m), and in the eastern part of the island lies the very active volcano, the Piton de la Fournaise (2632 m). The island harbours a wide variety of natural habitats (tropical montane cloud forests, subalpine shrublands, lowland forests, dry forest…), now all remnant in the Mascarene archipelago, that host high levels of endemism for both flora and fauna. Thereby, La Réunion is the most significant contributor towards conservation of terrestrial biodiversity in the Mascarene islands. The Divines project (FEDER) aims at developing innovative methods for characterizing and monitoring terrestrial biodiversity in the long term for conservation managers to ensure the protection of this world heritage site. In this poster, a description of the goals, actions and preliminary results of the DIVINES project will be described from gene to ecosystem levels

Linear resistivity and Sachdev-Ye-Kitaev (SYK) spin liquid behavior in a quantum critical metal with spin-1/21/2 fermions

`Strange metals' with resistivity depending linearly on temperature $T$ down to low-$T$ have been a long-standing puzzle in condensed matter physics. Here, we consider a model of itinerant spin-$1/2$ fermions interacting via on-site Hubbard interaction and random infinite-ranged spin-spin interaction. We show that the quantum critical point associated with the melting of the spin-glass phase by charge fluctuations displays non-Fermi liquid behaviour, with local spin dynamics identical to that of the Sachdev-Ye-Kitaev family of models. This extends the quantum spin liquid dynamics previously established in the large-$M$ limit of $SU(M)$ symmetric models, to models with physical $SU(2)$ spin-$1/2$ electrons. Remarkably, the quantum critical regime also features a Planckian linear-$T$ resistivity associated with a $T$-linear scattering rate and a frequency dependence of the electronic self-energy consistent with the Marginal Fermi Liquid phenomenology

SIG ChAOS : Représentation (La) de l'environnement sonore urbain à l'aide d'un système d'information géographique, Tome 1 et 2

Cette recherche a pour but de développer la représentation qualitative des phénomènes sonores urbains dans le sens d'une exploitation opérationnelle, en explorant les possibilités d'un Système d'Information Géographique (SIG)

Beam damage detection using synchronisation of peaks in instantaneous frequency and amplitude of vibration data

This paper explores the advantages of Variational Mode Decomposition (VMD) in detecting local damage on beam type structures (bridge) subjected to a sprung mass (vehicle). VMD is used to decompose the acceleration time history of the bridge at its midspan into its constitutive intrinsic mode functions (IMFs). The instantaneous frequency (IF) and instantaneous amplitude (IA) of the first IMF show irregularities at the damage position. We demonstrate through computer simulation that VMD is superior for detecting damage when compared to the well-known Empirical Mode Decomposition (EMD) method. A new damage sensitive feature (DSF) is also introduced that considers synchronisation of peaks between the IA and IF signals. The results show that the new DSF can enhance the peak at the damage positions while suppressing peaks at other locations

Habitat loss and frugivores defaunation in Réunion island (Indian Ocean)

Whereas human settlement on Mascarene islands occurred only recently during the 17th century, the native insular biota experienced a drastic extinction of the vertebrate fauna mainly explained by rapid habitat transformation. At archipelago scale, La R´eunion is the last of the Mascarene islands with large areas of untransformed habitats still covering 40% of the island area (2512 km2). Conversely, Mauritius native forests covers less than 1% of the initial area (1872 km2) but still retain several native frugivore species that went extinct in La Reunion during early human settlement (fruit bats, skinks, pigeons). In order to explain these patterns, we compare habitat transformation history between both islands using past and present vegetation maps, subfossil archives and reports of early travellers. We also question the consequences of native frugivores extinction at island scale. Preliminary results of forest dynamics studies confirm the lack of recovery of native plant communities after natural disturbance that can be explained by dispersal limitation of most native trees, new plant invasions and drastic changes in frugivores community composition