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Dhirendra Singh

Publications and source records attributed to Dhirendra Singh.

8 recordsLinked to original sources

Social Media Data Mining of Human Behaviour during Bushfire Evacuation

Traditional data sources on bushfire evacuation behaviour, such as quantitative surveys and manual observations have severe limitations. Mining social media data related to bushfire evacuations promises to close this gap by allowing the collection and processing of a large amount of behavioural data, which are low-cost, accurate, possibly including location information and rich contextual information. However, social media data have many limitations, such as being scattered, incomplete, informal, etc. Together, these limitations represent several challenges to their usefulness to better understand bushfire evacuation. To overcome these challenges and provide guidance on which and how social media data can be used, this scoping review of the literature reports on recent advances in relevant data mining techniques. In addition, future applications and open problems are discussed. We envision future applications such as evacuation model calibration and validation, emergency communication, personalised evacuation training, and resource allocation for evacuation preparedness. We identify open problems such as data quality, bias and representativeness, geolocation accuracy, contextual understanding, crisis-specific lexicon and semantics, and multimodal data interpretation.

cs.SI

Fundamental Understanding of Exposure and Process Chemistry for Enhanced Lithography and Stability of Metal Oxide Resists

Metal oxide resists (MORs) have shown great promise for high resolution patterning in extreme ultraviolet (EUV) lithography, with potential for integration into high volume manufacturing. However, MORs have recently been shown to exhibit sensitivity to process conditions and environment, leading to critical dimension (CD) variation. While this variation can be reduced with proper process control, there is little knowledge on how these aspects affect the image formation mechanism. To bridge these knowledge gaps, we deploy a coordinated, fundamentals-focused approach to yield deep insights into MOR exposure and process chemistry. Our results on a model MOR, an n-butyl Sn-Oxo system, reveal how parameters such as exposure dose, post-exposure bake temperature, and atmospheric species influence the image formation mechanism. Our results, and the coordinated approach using correlative spectroscopies, provide a strong foundation for understanding the image formation mechanism in MOR materials with potential to link mechanistic aspects to CD variation.

cond-mat.mtrl-sci

An Activity-Based Model of Transport Demand for Greater Melbourne

In this paper, we present an activity-based model for the Greater Melbourne area, using a combination of hierarchical clustering, probabilistic, and gravity-based approaches. The model outlines steps for generating a synthetic population-a list of agents with their demographic attributes-and for assigning activity patterns, schedules, as well as activity locations and modes of travel for each trip. In our model, individuals are assigned activity chains based on the probabilities of their respective demographic clusters, as informed by observed data. Tours and trips then emanate from these assigned activities. This is innovative compared to the common practice of creating trips or tours first and attaching activities thereafter. Furthermore, when selecting activity locations, our model incorporates both the distance-decay of trip lengths and the activity-based attraction of destination sites. This results in areas with higher attractiveness for various activities showing a greater likelihood of being selected. Additionally, when assigning the location for the next activity, we take into account the number of activities an agent has remaining to ensure they do not opt for a location that would be impractical for a return trip home. Our methodology is open and replicable, requiring only publicly available data and is designed to produce outcomes compatible with commonly used agent-based modeling software such as MATSim. Each sub-model is calibrated to match observed data in terms of activity types, start and end times, and durations.

cs.AI

Activity-based and agent-based Transport model of Melbourne (AToM): an open multi-modal transport simulation model for Greater Melbourne

Agent-based and activity-based models for simulating transportation systems have attracted significant attention in recent years. Few studies, however, include a detailed representation of active modes of transportation - such as walking and cycling - at a city-wide level, where dominating motorised modes are often of primary concern. This paper presents an open workflow for creating a multi-modal agent-based and activity-based transport simulation model, focusing on Greater Melbourne, and including the process of mode choice calibration for the four main travel modes of driving, public transport, cycling and walking. The synthetic population generated and used as an input for the simulation model represented Melbourne's population based on Census 2016, with daily activities and trips based on the Victoria's 2016-18 travel survey data. The road network used in the simulation model includes all public roads accessible via the included travel modes. We compared the output of the simulation model with observations from the real world in terms of mode share, road volume, travel time, and travel distance. Through these comparisons, we showed that our model is suitable for studying mode choice and road usage behaviour of travellers.

physics.soc-ph

What will they do? Modelling self-evacuation archetypes

A decade on from the devastating Black Saturday bushfires in Victoria, Australia, we are at a point where computer simulations of community evacuations are starting to be used within the emergency services. While fire progression modelling is embedded in strategic and operational settings at all levels of government across Victoria, modelling of community response to such fires is only just starting to be evaluated in earnest. For community response models to become integral to bushfire planning and preparedness, the key question to be addressed is: when faced with a bushfire, what will a community really do? Typically this understanding has come from local experience and expertise within the community and services, however the trend is to move towards more informed data driven approaches. In this paper we report on the latest work within the emergency sector in this space. Particularly, we discuss the application of Strahan et al.'s self-evacuation archetypes to an agent-based model of community evacuation in regional Victoria. This work is part of the consolidated bushfire evacuation modelling collaboration between several emergency management stakeholders.

cs.AI

Building the road network for city-scale active transport simulation models

In this paper, we introduce and test our algorithm to create a road network representation for city-scale active transportation simulation models. The algorithm relies on open and universal data to ensure applicability for different cities around the world. In addition to the major roads, their geometries and the road attributes typically used in transport modelling (e.g., speed limit, number of lanes, permitted travel modes), the algorithm also captures minor roads usually favoured by pedestrians and cyclists, along with road attributes such as bicycle-specific infrastructure, traffic signals, and road gradient. Furthermore, it simplifies the network's complex geometries and merges parallel roads if applicable to make it suitable for large-scale simulations. To examine the utility and performance of the algorithm, we used it to create a network representation for Greater Melbourne, Australia and compared the output with a network created using an existing transport simulation toolkit along with another network from an existing city-scale transport model from the Victorian government. Through simulation experiments with these networks, we illustrated that our algorithm achieves a very good balance between simulation accuracy and run-time. For routed trips on our network for walking and cycling it is of comparable accuracy to the common network conversion tools in terms of travel distances of the shortest paths while being more than two times faster when used for simulating different sample sizes. Therefore, our algorithm offers a flexible solution for building accurate and efficient road networks for city-scale active transport models for different cities around the world.

physics.soc-ph

Building a large synthetic population from Australian census data

We present work on creating a synthetic population from census data for Australia, applied to the greater Melbourne region. We use a sample-free approach to population synthesis that does not rely on a disaggregate sample from the original population. The inputs for our algorithm are joint marginal distributions from census of desired person-level and household-level attributes, and outputs are a set of comma-separated-value (.csv) files containing the full synthetic population of unique individuals in households; with age, gender, relationship status, household type, and size, matched to census data. Our algorithm is efficient in that it can create the synthetic population for Melbourne comprising 4.5 million persons in 1.8 million households within three minutes on a modern computer. Code for the algorithm is hosted on GitHub.

stat.AP

Analyzing conformational changes in single FRET-labeled A1 parts of archaeal A1AO-ATP synthase

ATP synthases utilize a proton motive force to synthesize ATP. In reverse, these membrane-embedded enzymes can also hydrolyze ATP to pump protons over the membrane. To prevent wasteful ATP hydrolysis, distinct control mechanisms exist for ATP synthases in bacteria, archaea, chloroplasts and mitochondria. Single-molecule Förster resonance energy transfer (smFRET) demonstrated that the C-terminus of the rotary subunit epsilon in the Escherichia coli enzyme changes its conformation to block ATP hydrolysis. Previously we investigated the related conformational changes of subunit F of the A1AO-ATP synthase from the archaeon Methanosarcina mazei Gö1. Here, we analyze the lifetimes of fluorescence donor and acceptor dyes to distinguish between smFRET signals for conformational changes and potential artefacts.

q-bio.BM