Leonel Aguilar Melgar

Last Name

Aguilar Melgar

First Name

Leonel

ORCID

0000-0001-6864-4492

Organisational unit

03987 - Hölscher, Christoph / Hölscher, Christoph

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Publications 1 - 10 of 17

Experiments as Code and its application to VR studies in human-building interaction
Aguilar Melgar, Leonel; Gath-Morad, Michal; Grübel, Jascha; et al. (2024)
Scientific Reports
Experiments as Code (ExaC) is a concept for reproducible, auditable, debuggable, reusable, & scalable experiments. Experiments are a crucial tool to understand Human-Building Interactions (HBI) and build a coherent theory around it. However, a common concern for experiments is their auditability and reproducibility. Experiments are usually designed, provisioned, managed, and analyzed by diverse teams of specialists (e.g., researchers, technicians, engineers) and may require many resources (e.g., cloud infrastructure, specialized equipment). Although researchers strive to document experiments accurately, this process is often lacking. Consequently, it is difficult to reproduce these experiments. Moreover, when it is necessary to create a similar experiment, the “wheel is very often reinvented”. It appears easier to start from scratch than trying to reuse existing work. Thus valuable embedded best practices and previous experiences are lost. In behavioral studies, such as in HBI, this has contributed to the reproducibility crisis. To tackle these challenges, we propose the ExaC paradigm, which not only documents the whole experiment, but additionally provides the automation code to provision, deploy, manage, and analyze the experiment. To this end, we define the ExaC concept, provide a taxonomy for the components of a practical implementation, and provide a proof of concept with an HBI desktop VR experiment that demonstrates the benefits of its “as code” representation, that is, reproducibility, auditability, debuggability, reusability, & scalability.
cogARCH: Simulating Wayfinding by Architecture in Multilevel Buildings
Gath Morad, Michal; Aguilar Melgar, Leonel; Conroy Dalton, Ruth; et al. (2020)
2020 Proceedings of the Symposium on Simulation for Architecture and Urban Design
Findings from cognitive science link the architectural complexity of multilevel buildings with occupants’ difficulty in orienting and finding their way. Nevertheless, current approaches to modelling occupants’ wayfinding reduce the representation of 3D multilevel buildings to isolated 2D graphs of each floor. These graphs do not take account of the interplay between agents’ 3D field of view and buildings’ 3D geometry, topology, or semantics, yet these are necessary to inform occupants’ path differentiation during wayfinding. Instead, agents are often modeled as unbounded and rational, able to calculate complete paths towards goals that are not immediately visible using direct routing algorithms. In turn, simulated behavior in most cases is unrealistically optimal (e.g. shortest or fastest route). This gap may hinder architects’ ability to foresee how their design decisions may result in suboptimal wayfinding behavior, whether intended or not. To bridge this gap, the paper presents cogARCH, a computational, agent-based simulation framework. cogARCH is grounded in research on spatial cognition and heuristic decision making to support pre-occupancy evaluation of wayfinding in multilevel buildings. To demonstrate the relevance of cogARCH to architectural design, we apply it to assess wayfinding performance across three architectural variations of a multilevel education building. Preliminary results showcase significant variability in cognitive agents’ wayfinding performance between building scenarios. In contrast, behavior of shortest-path agents sampled across respective conditions displayed significantly less variance and thus failed to reflect potential effects of architectural changes applied to 3D building configuration on wayfinding behavior.
Scalable HPC enhanced agent based system for simulating mixed mode evacuation of large urban areas
Wijerathne, Lalith; Petprakob, Wasuwat; Aguilar Melgar, Leonel; et al. (2018)
Transportation Research Procedia
This short paper presents an HPC enhanced Agent Based Model (ABM) developed with the aim of quantitatively estimating the strategies for accelerating emergency mass evacuations, like tsunami evacuation. In order to facilitate inclusion of various influencing factors, such as localized congestion, multi-modes, pedestrian vehicle interactions, fallen debris from damaged buildings, visibility, etc., which demand detailed models, the developed system includes a 1mx1m resolution model of environment, and agents capable of perceiving and autonomously interact with this high resolution environment and visible agents. In order to meet the computational demand of large scale simulations with complex agents, a scalable high performance extension was implemented. Short introductions to the agent based model and the HPC extension are presented in this paper. In order to demonstrate the scalability of the system, both in problem size and computational capability, a 588 km2 region with 10 million agents is simulated in K computer. It is demonstrated that the system has high strong scalability up to 2048 computing nodes, which is equivalent to 16,384 CPU cores.
How learning can change the course of evolution
Aguilar Melgar, Leonel; Bennati, Stefano; Helbing, Dirk (2019)
PLoS ONE
The interaction between phenotypic plasticity, e.g. learning, and evolution is an important topic both in Evolutionary Biology and Machine Learning. The evolution of learning is commonly studied in Evolutionary Biology, while the use of an evolutionary process to improve learning is of interest to the field of Machine Learning. This paper takes a different point of view by studying the effect of learning on the evolutionary process, the so-called Baldwin effect. A well-studied result in the literature about the Baldwin effect is that learning affects the speed of convergence of the evolutionary process towards some genetic configuration, which corresponds to the environment-induced plastic response. This paper demonstrates that learning can change the outcome of evolution, i.e., lead to a genetic configuration that does not correspond to the plastic response. Results are obtained both analytically and experimentally by means of an agent-based model of a foraging task, in an environment where the distribution of resources follows seasonal cycles and the foraging success on different resource types is conditioned by trade-offs that can be evolved and learned. This paper attempts to answer a question that has been overlooked: whether learning has an effect on what genotypic traits are evolved, i.e. the selection of a trait that enables a plastic response changes the selection pressure on a different trait, in what could be described as co-evolution between different traits in the same genome.
Parenting in the Digital Age: A Scoping Review of Digital Early Childhood Parenting Interventions in Low- and Middle-Income Countries (LMIC)
Jäggi, Lena; Hartinger, Stella M.; Fink, Günther; et al. (2025)
Public Health Reviews
Objectives: This scoping review examines the evidence and knowledge gaps regarding the effectiveness of digital early childhood parenting interventions in Low- and Middle-Income Countries (LMICs). Methods: Using PRISMA-ScR and PICOS frameworks, we systematically reviewed studies published since 2010 from four databases, focusing on the impact of digital parenting interventions on Early Childhood Development and parent-level outcomes. Results: Of 1,399 studies identified, 13 met inclusion criteria, evaluating digital interventions for parents of children aged 0–5 years. These interventions included digital-only and hybrid approaches, leveraging technologies for tasks such as sharing health and ECD information, reminders, group chats, or screening. Among ECD studies, three of four with parent-reported outcomes found positive effects, but none of three using direct assessments did. Parent-level outcomes, such as mental health and parenting behaviors, showed consistent positive impacts. Conclusion: Digital parenting interventions are feasible in LMICs but face challenges in implementation and reaching vulnerable families. Most studies are small-scale with variable designs and outcomes. Rigorous, high-quality studies are needed to establish effectiveness and optimize implementation strategies before these programs are deployed at scale.
Spatial and operational interventions for healthy cruise ship design using agent-based modelling
Pan, Jiayu; Aguilar Melgar, Leonel; Gath-Morad, Michal; et al. (2026)
Travel Behaviour and Society
Cruise ship environments have been identified as high-risk settings for communicable disease outbreaks. The severe COVID-19 outbreaks aboard several cruise ships have further intensified concerns about transmission in these confined, densely populated environments. Although some behavioural interventions have been studied, the influence of spatial and operational design on transmission risk remains under explored. To address this gap, this study applies agent-based modelling (ABM) to simulate passenger movement patterns on mixed-use cruise ship decks as a surrogate for infection transmission. By modelling individual movement behaviours and collisions (close-contact exposure) within the mixed-use decks, the ABM approach supports the development of spatial design and operational strategies that can reduce transmission risk and improve the efficiency and healthiness of onboard circulation. We conducted verification and parametric tests to assess model performance and designed three experiments to evaluate the effects of varying occupancy levels, infection prevalence, spatial layouts and access restriction strategies with 1181 simulation runs, the simulation results are complemented by spatial analyses of deck plans to inform evidence-based recommendations for safer cruise ship environments. We identified three key spatial drivers of disease transmission risk on cruise ships. First, higher occupancy density and compact layouts significantly increased close-contact events, as passengers navigated narrow, poorly connected corridors. Second, the effectiveness of quarantine interventions depended not just on their presence but on their spatial placement: centrally located restrictions amplified congestion, while peripheral placement helped alleviate it. Third, simple passive design changes-such as widening corridors or enhancing internal connectivity-reduced movement bottlenecks and collisions, without requiring behavioural adaptation. Together, these findings demonstrate that spatial configuration is not merely a backdrop but a powerful determinant of health resilience in high-occupancy environments.
Beyond the shortest-path: Towards cognitive occupancy modeling in BIM
Gath Morad, Michal; Aguilar Melgar, Leonel; Conroy Dalton, Ruth; et al. (2022)
Automation in Construction
Current approaches to simulate occupants' wayfinding in AEC mostly employ direct routing algorithms that assume global knowledge of the navigation environment to compute a shortest path between two locations. This simplification overlooks evidence concerning the role of perception and cognition during wayfinding in complex buildings, leading to potentially erroneous predictions that may hinder architects' ability to design wayfinding by architecture. To bridge this gap, we present a novel simulation paradigm entitled Cognitive Occupancy Modeling in BIM to simulate wayfinding by means of a vision-based cognitive agent and a semantically-enriched navigation space extracted from BIM (Building Information Modeling). To evaluate the predictive power of the proposed paradigm against human behavior, we conducted a wayfinding experiment in Virtual Reality (VR) with 149 participants, followed by a series of simulation experiments with cognitive and direct routing agents. Results highlight a significant correspondence between human participants' and cognitive agents' wayfinding behavior that was not observed with direct routing agents, demonstrating the potential of cognitive modeling to inform building performance simulations in AEC.
The role of strategic visibility in shaping wayfinding behavior in multilevel buildings
Gath Morad, Michal; Grübel, Jascha; Steemers, Koen; et al. (2024)
Scientific Reports
In this paper, we explore the mutual effect of prior background expectations and visibility afforded by the 3D configuration of the physical environment on wayfinding efficiency and strategy in multilevel buildings. We perform new analyses on data from 149 participants who performed six unaided and directed wayfinding tasks in virtual buildings with varying degrees of visibility. Our findings reveal that the interaction between visibility and prior background expectations significantly affects wayfinding efficiency and strategy during between-floor wayfinding tasks. We termed this interaction effect strategic visibility, which emphasizes the importance of the strategic allocation of visibility towards actionable building elements in promoting efficient wayfinding and shaping wayfinding strategy. Our study highlights the significance of strategic visibility in promoting inclusive and accessible built environments for neurodiversity. Finally, we provide an open-source dataset that can be used to develop and test new wayfinding theories and models to advance research in the emerging field of human-building interaction.
Digital Support Systems to Improve Child Health and Development in Peru: Protocol for a Randomized Controlled Trial
Hartinger Pena, Stella Maria; Mäusezahl, Daniel; Jäggi, Lena; et al. (2023)
JMIR Research Protocols
Background: Children living in low and middle-income countries (LMICs) are at greater risk for experiencing adversities that can undermine their health and early development. Recently launched digital early childhood development (ECD) programs attempt to support families with young children in their home environments using digital technologies. However, relatively little is known regarding the effectiveness of these new technologies. Objective: The goal of this study is to rigorously assess the reach, effectiveness, and cost-effectiveness of a newly developed digital ECD platform called Afini. The Afini platform was designed to support parents of young children in low-resource settings to improve ECD and interact with caregivers through messenger services and a chatbot. Methods: This is a 3-arm cluster randomized controlled trial. In total, 2471 caregivers and their 3- to 9-month-old children were enrolled in the study across 164 study clusters in the San Marcos, Cajabamba, and Cajamarca provinces of Peru. Clusters of participants were randomly assigned to 1 of 3 groups: a control group (72 community clusters and 980 caregiver-child dyads), a home visit intervention group (20 community clusters and 316 caregiver-child dyads), and an Afini intervention group (72 community clusters and 1175 caregiver-child dyads). Families in the control group receive no focused ECD intervention. The home visit group is receiving biweekly home visits by a trained field staff following the national ECD program (Programa Nacional Cuna Más) curriculum and training guidelines. Caregivers in the Afini group are receiving ECD activities and advice through the digital platform. The primary study outcome is children’s overall development at the age of 2.5 years, using the internationally validated long form of the Global Scales for Early Development. Secondary outcomes include caregiver engagement; caregiver mental health; screen time; as well as caregiver reports of children’s motor, cognitive, language, and socioemotional development measured through locally piloted and validated tools. Results: Enrollment started in September 2021 and ended in March 2023. Endline assessments will take place between August 2023 and September 2024. Conclusions: This study is, to our knowledge, the first to rigorously assess the effectiveness and cost-effectiveness of digital ECD technologies in LMICs. Given the large number of children in LMICs currently receiving only limited external support, the evaluated platform has the potential to improve the short- and long-term well-being of millions of children and their parents globally.
Digital tools to improve parenting behaviour in low-income settings: a mixed-methods feasibility study
Jäggi, Lena; Aguilar Melgar, Leonel; Alvarado Llatance, Milagros; et al. (2023)
Archives of Disease in Childhood
Introduction Digital parenting interventions could be potentially cost-effective means for providing early child development services in low-income settings. This 5-month mixed-methods pilot study evaluated the feasibility of using Afinidata, a comprehensive Facebook Messenger-based digital parenting intervention in a remote rural setting in Latin America and explored necessary adaptations to local context. Methods The study was conducted in three provinces in the Cajamarca region, Peru, from February to July 2021. 180 mothers with children aged between 2 and 24 months and regular access to a smartphone were enrolled. Mothers were interviewed three times in-person. Selected mothers also participated in focus groups or in-depth qualitative interviews. Results Despite the rural and remote study site, 88% of local families with children between 0 and 24 months had access to internet and smartphones. Two months after baseline, 84% of mothers reported using the platform at least once, and of those, 87% rated it as useful to very useful. After 5 months, 42% of mothers were still active on the platform, with little variation between urban and rural settings. Modifications to the intervention focused on assisting mothers in navigating the platform independently and included adding a laminated booklet with general information on child development, sample activities and detailed instructions on how to self-enrol in case of lost phones. Conclusions We found high access to smartphones and the intervention was well received and used in very remote areas of Peru, suggesting that digital parenting interventions could be a promising path forward for supporting low-income families in remote parts of Latin America.

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