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A dynamic model has been developed to simulate aspects of feedlot lamb growth and body composition, including energy and protein requirements, growth rate, composition of gain, and body mass. Model inputs include initial body mass (kg), standard final mass (kg), age (days), and dietary energy concentration (Mcal·kg-1). The model was assessed as a decision support tool using a dataset of 564 individual measures of final body mass and diet energy. The simulations provide graphical and numerical descriptions of nutrient requirements, composition of gain, and estimates of animal performance over time. The model is accurate and precise, with a root mean squared error of 7.79% of the observed final body mass and a coefficient of determination of 0.89 when simulating the same variable. The model can be used as a reliable decision support tool to estimate final body mass and the days on feed required to reach a certain final mass with precision and accuracy. Moreover, the dynamic model can also serve as a learning tool to illustrate practical principles of animal nutrition, nutrient requirement relationships, and body composition changes. This model holds the potential to enhance livestock management practices and assist producers in making informed decisions about feedlot lamb production.

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This article addresses the impact of transient pressure anomalies in hydraulic systems, triggered by the opening or closing of valves or pumps, instantly disturbing the line of hydraulic gradient (LGH). This variation in pressure has significant consequences both in hydraulic and structural terms for water networks. Most of the existing techniques to detect transients in water distribution systems use asynchronous methods, generating timeless information that limits the response capacity in critical situations. Therefore, an automatic transient detection system based on the Internet of Things (IoT) is proposed, capable of identifying overpressure or underpressure pulses in soft real-time, activating alarms to facilitate decision-making. This approach helps maintain the safety of the water distribution system and prevent leaks in the network. Furthermore, a model of the transient behavior of pressure and flow is presented by linearizing the water hammer equations from the Laplace transform, thus generating a transfer function that describes the algebraic relationship between the outlet and inlet of the hydraulic system.•The transient analysis of the hydraulic system prototype underscores its high sensitivity to initial conditions, attributed to turbulence. This observation suggests the possible presence of a dynamic strange attractor related to water hammer phenomena in pressure pipes.•The methodology involving transfer functions and state-space models enables the assessment of how leaks impact the transient responses of the system, including the magnitude, duration, and frequency of disturbances generated by them.•The proposed method introduces a dynamic transfer function capable of identifying instantaneous changes over time in terms of flow and pressure.

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Scenario and policy assessments in socioeconomic and environmental studies face significant challenges in socio-ecological systems (SES). There are a limited number of studies that have looked at the impact of different scenarios within integrated approaches, and many have used a static approach with a single driver of change. The present work analyzes the SES dynamics for a strategic basin in the Colombian Andes when implementing and analyzing scenarios and policies related to land cover and land use change using a system dynamics simulation model. The model includes natural, ecosystem services, sociocultural, and economic components. Scenarios and policy options are analyzed both individually and jointly to identify synergies or trade-off effects between the different SES components. The results showed the different trajectories of the socio-ecological system according to the cases studied, and its impact on different variables in the analyzed components. Some counterintuitive effects were also identified, such as the importance of intrinsic motivations in decision-making processes, and determinants in land management and policy design.

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Systems modeling offers a valuable tool to support strategic decision-making for complex problems because it considers the causal inter-relationships that drive population health outcomes. This tool can be used to simulate policies and initiatives to determine which combinations are likely to deliver the greatest impacts and returns on investment. Systems modeling benefits from participatory approaches where a multidisciplinary stakeholder group actively engages in mapping and contextualizing causal mechanisms driving complex system behaviors. Such approaches can have significant advantages, including that they may improve connection and coordination of the network of stakeholders operating across the system; however, these are often observed in practice as colloquial anecdotes and seldom formally assessed. We used a basic social network analysis to explore the impact on the configuration of the network of mental health providers, decision-makers, and other stakeholders in Bogota, Colombia active in a series of three workshops throughout 2021 and 2022. Overall, our analysis suggests that the participatory process of the systems dynamics exercise impacts the social network's structure, relationships, and dynamics.

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OBJECTIVE: We investigate the obesity transition at the country- and regional-levels, by age, gender, and socioeconomic status (SES) and its relationship to three health behavior attributes, including physical activity (PA), sedentary activities (ST), and consumption of ultra-processed foods (CUPF) within the urban population of Colombia, from 20,010 to 2050. METHODS: The study is informed by cross-sectional data from ENSIN survey. We used these data to develop a system dynamics model that simulates the dynamics of obesity by body mass index (BMI) categories, gender, and SES. This model also uses a conservative co-flow structure for three health-related behaviors (PA, ST, and CUPF). RESULTS: At the national level, our results indicate that the burden of obesity is shifting towards populations with lower SES as the gross domestic product (GDP) increases, particularly women aged 20-59 years with lower SES. Among this group of women, the highest burden of obesity is among those who do not meet the PA, ST and CUPF recommendations. At the regional level, our findings suggest that the regions are at different stages in the obesity transition. CONCLUSIONS: The burden of obesity is shifting towards women with lower SES as GDP increases at the national level and across several regions. This obesity transition is paralleled by a high prevalence of women from low SES groups who do not meet the minimum recommendations for PA, CUPF, and ST. Our findings can be used by decision-makers to inform age- and SES- specific policies seeking to tackle the obesity.

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BACKGROUND: The occupational activities carried out in hospital environments pose occupational risks to professionals. In psychiatric hospitals, due to the characteristics of the patients treated, professionals are also subjected to other risks, such as physical aggression. OBJECTIVE: This research aimed to identify the systemic context, highlighting the cause-and-effect relationships that culminate in occupational accidents that occurred with the nursing staff in a psychiatric hospital in Brazil. METHODS: The current study is an applied research and was divided into three stages. First, the collection of data related to the case study was made and accidents were analyzed and occupational hazards were identified. In the second stage, from the collected information, occupational safety indicators were defined. Lastly, in the third stage, the qualitative aspect of System Dynamics was applied to perform the systemic analysis and to identify how the different variables were related. RESULTS: The results showed that physical aggression was the main cause of accidents. Regarding safety indicators, while both the level of use of Personal Protective Equipment (PPE) by professionals and the high level of PPE protection were positive aspects, the level of training of professionals to use PPE was a negative aspect. The Causal Link Diagram (CLD) showed that the perception of risk influenced the level of use of PPE and those organizational measures influenced the accident rate. CONCLUSION: In conclusion, the systemic analysis of the system dynamics can optimize the diagnostic process of occupational accidents in psychiatric hospitals, and especially help to identify the cause and effect among the variables involved.

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In December 2019, coronavirus disease (COVID-19) was detected in Wuhan, China. Due to the rapid spread of the disease, containment measures were adopted, which caused unprecedent shifts in individual mobility. Although some studies explored the impacts of the COVID-19 pandemic on travel patterns and resilience of transport systems based on different analysis techniques, there is a lack of studies addressing the impacts of the pandemic on the sustainability and resilience of urban mobility systems using in-depth and holistic methods, such as system dynamics. This research aims to characterize the dynamics present in urban mobility systems when exposed to pandemics and analyze the changes needed for systems to increase their resilience to pandemics using qualitative system dynamics modeling. The framework comprises the characterization of cause-and-effect relationships and the creation of systems' causal loop diagrams (CLD) in their basic state of functionality, when affected by pandemics, and still operating owing to its resilience. Our findings indicated that the CLD of a resilient system is driven by strategic preparedness and response plans, as well as research and development, which balance the spread of the pandemic and increase support on technological strengths and the activities performed from home.

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Collaboration mechanisms in humanitarian supply chains increase efficiency levels in post-disaster relief operations. The scientific literature on the topic is mostly based on qualitative approaches to identify the barriers and benefits of collaborative relationships between stakeholders. Thus, this paper proposes the use of system dynamics simulation to evaluate the impact on the average response time of aid delivery resulting from implementing different collaborative strategies. In this sense, collaborative strategies are designed for humanitarian operations in the immediate response phase considering elements such as information exchange, shared resources, and infrastructure. To design and assess the impact of these collaborative strategies in a disaster scenario, we analyze the case of the city of Bogotá-Colombia and the surrounding cities, we have used public information for building and tuning the parameters of the simulation model. The simulation model results allow us to identify the main factors that reduce the average response times to serve the affected population. It can be concluded that the strategy which includes sharing resources and infrastructure, exchanging information, and the creation of joint knowledge has a greater improvement in response times becoming the best policy for disaster management given the results obtained in a collaborative planning environment.

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This paper aims to make a proposal to govern the Peruvian State under the umbrella of management cybernetics, following the paths of the viable system model (VSM), proposed by Prof. Stafford Beer, enriched with other soft and hard systemic methodologies and technologies, to cover the soft and hard issues that are part of the complex Peruvian reality at different levels of recursion. For doing this, four defined perspectives were adopted to understand the complexity of Peru: the sectoral view, the regions view, the river basins view and the macroregions view. Peru is seen as a system in focus, defining, for each of these four perspectives, the five systems that VSM has. The application of the VSM in each perspective serves to apply it in two modes: diagnosis and design, according to the respective perspective. Then an integrative analysis and reflection is done considering the four perspectives, to analyze the viability of the VSM approach in the governance of the Peruvian State to establish some conclusions and recommendations in relation to the proposal, appearing at the end of the paper.

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Public policies, incentives, and infrastructure are top-down instruments that can align stakeholders' roles and expectations for Circular Economy (CE) transitions, but it is crucial to analyse the possible effects of such instruments before implementation. This research investigates the Brazilian Industrial Agreement for Electrical and Electronic Equipment (BIAEEE) that governs the responsibilities and targets for nationwide collection and treatment of Waste from Electrical and Electronic Equipment (WEEE). A system dynamics simulation model is adapted for the use of smartphones in Brazil, and interventions focused on the collection of end-of-life products are examined against the BIAEEE targets. Twelve policy scenarios investigate three aspects of EEE collection: coverage increase, distribution of collection points and rewards. All scenarios show improvement in the EEE collection, but only one meets the BIAEEE targets. This research demonstrates how modelling and simulation can inform strategic decision-making in public policies for CE transitions.

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Similar interventions to stop the spread of COVID-19 led to different outcomes in Latin American countries. This study aimed to capture the multicausality of factors affecting HS-capacity that could help plan a more effective response, considering health as well as social aspects. A facilitated GMB was constructed by experts and validated with a survey from a wider population. Statistical analyses estimated the impact of the main factors to the HS-capacity and revealed the differences in its mechanisms. The results show a similar four-factor structure in all countries that includes public administration, preparedness, information, and collective self-efficacy. The factors are correlated and have mediating effects with HS-capacity; this is the base for differences among countries. HS-capacity has a strong relation with public administration in Bolivia, while in Nicaragua and Uruguay it is related through preparedness. Nicaragua lacks information as a mediation effect with HS-capacity whereas Bolivia and Uruguay have, respectively, small and large mediation effects with it. These outcomes increase the understanding of the pandemic based on country-specific context and can aid policymaking in low-and middle-income countries by including these factors in future pandemic response models.

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RESUMEN La planificación del flujo de caja de un proyecto de construcción es una actividad decisiva para garantizar los recursos financieros que son necesarios para el desarrollo de las actividades de obra. Debido a la importancia, en la industria de la construcción se observa la necesidad de metodologías de análisis de flujo caja de adaptación fácil a las modificaciones, y con altos niveles de detalle, las cuales propicien mejoras en la precisión de las estimaciones y en la anticipación de situaciones problemáticas. Considerando esta necesidad, en este artículo se propone un nuevo esquema metodológico para la planificación del flujo de caja de proyectos de construcción, el cual está basado en la integración de modelos del proceso constructivo BIM 5D (Building Information Modeling 5D), y dinámica de sistemas. El esquema que es propuesto consta de seis etapas principales: 1) modelo BIM 3D, cantidades y rendimientos, 2) estructura desglosada del trabajo, 3) estimación de costos, 4) modelado y simulación digital BIM 5D, 5) análisis del flujo de caja, y 6) implementación de la alternativa. La aplicación del esquema indica que la rapidez, visualización y automatización, con la que se desarrolla la planificación del flujo de caja, propicia el análisis de varias alternativas; lo cual fortalece los procesos de toma de decisiones, y mejora los resultados de la planificación.

ABSTRACT Cash flow planning of a construction project is a crucial activity to guarantee the financial resources necessary for construction activities development. Due to the importance, there is a need for cash flow analysis methodologies that are easy to adapt to modifications and involve high levels of detail, which allow improving precision in estimations and anticipating possible problematic events. Considering this need, this paper proposes a new methodological scheme for cash flow planning of construction projects, which is based on construction process models BIM 5D (Building Information Modeling 5D), and system dynamics. The proposed scheme consists of six main stages: 1) BIM 3D model and quantities, 2) work breakdown structure, 3) cost estimation, 4) BIM 5D digital modeling and simulation, 5) cash flow analysis, and 6) implementation. The application of the proposed scheme indicates that the speed, visualization, and automation, with which the cash flow planning is developed, favors the analysis of several alternatives, which strengthens decision-making processes, and improves planning results.

RESUMO O planeamento do fluxo de caixa de um projecto de construção é uma actividade decisiva para garantir os recursos financeiros necessários para o desenvolvimento das actividades de trabalho. Devido à sua importância, na indústria da construção há necessidade de metodologias de análise de fluxo de caixa que sejam facilmente adaptáveis às mudanças e com elevados níveis de detalhe, que permitam melhorar a precisão das estimativas e a antecipação de situações problemáticas. Considerando esta necessidade, este documento propõe um novo esquema metodológico para o planeamento do fluxo de caixa dos projectos de construção, que se baseia na integração do BIM 5D (Building Information Modeling 5D) e modelos de dinâmica do sistema do processo de construção. O esquema proposto consiste em seis fases principais: 1) modelo BIM 3D, quantidades e desempenhos, 2) estrutura de repartição do trabalho, 3) estimativa de custos, 4) modelação e simulação digital BIM 5D, 5) análise do fluxo de caixa, e 6) implementação da alternativa. A aplicação do esquema indica que a rapidez, visualização e automatização, com a qual o planeamento do fluxo de caixa é desenvolvido, é conducente à análise de várias alternativas; o que reforça os processos de tomada de decisão, e melhora os resultados do planeamento.

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BACKGROUND: Effectively bridging the knowledge-policy gap to support the development of evidence-based policies that promote health and well-being remains a challenge for both the research and policy communities. Community-based system dynamics (CBSD) is a participatory modelling approach that aims to build stakeholders' capacity to learn and address complex problems collaboratively. However, limited evidence is available about the contributions of CBSD to knowledge-generating and policy processes across sectors and policy spheres. In the context of a multi-country research project focused on creating an evidence base to inform urban health policies across Latin America, a series of CBSD workshops convened stakeholders from research, policy-making, and other backgrounds working in food and transportation systems. Diverse participants were selected aiming to incorporate multiple perspectives relevant to understanding complex urban systems linked to food and transportation. This study focuses on one of these workshops, whose avenue was São Paulo, Brazil, assembling country-based participants representing local, regional, national, and international institutions with multidisciplinary backgrounds linked to food and transportation systems. OBJECTIVE: The aim of this case study is to explore the perceived influence of one of these workshops on attendees' understandings of food and transportation systems and their relationship to healthy urban environments, with attention to the role of the workshop in supporting knowledge to policy translation for urban health. METHODS: We conducted 18 semi-structured qualitative interviews with attendees one year after their participation in a CBSD workshop held in São Paulo, Brazil. A framework method approach was used to code participants' responses and identify emerging themes. RESULTS: Participants reported that the workshop's group model-building activities influenced their understanding of the knowledge-policy process as it relates to food and transport systems. Workshop contributed to participants' (1) abilities to engage with multisectoral stakeholders, (2) construct a shared language and understanding of urban challenges, (3) improve understanding of the interconnectedness across food and transportation systems, (4) facilitate dialogue across sectors, and (5) apply a systems thinking approach within their sector and professional context. Participants continued to draw on the tools developed during the workshop, and to apply systems thinking to their research and policy-making activities. CONCLUSIONS: CBSD may offer valuable opportunities to connect the research sector to the policy-making process. This possibility may contribute to knowledge to policy translation in the interconnection between the urban context, food and transportation systems, and health.

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Internet of Things (IoT) should not be seen only as a cost reduction mechanism for manufacturing companies; instead, it should be seen as the basis for transition to a new business model that monetizes the data from an intelligent ecosystem. In this regard, deciphering the operation of the value creation system and finding the balance between the digital strategy and the deployment of technological platforms, are the main motivations behind this research. To achieve the proposed objectives, systems theory has been adopted in the conceptualization stage, later, fuzzy logic has been used to structure a subsystem for the evaluation of input parameters. Subsequently, system dynamics have been used to build a computational representation and later, through dynamic simulation, the model has been adjusted according to iterations and the identified limits of the system. Finally, with the obtained set of results, different value creation and capture behaviors have been identified. The simulation model, based on the conceptualization of the system and the mathematical representation of the value function, allows to establish a frame of reference for the evaluation of the behaviour of IoT ecosystems in the context of the connected home.

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Abstract Populations living in favelas are facing even more vulnerabilities with the sudden escalation of the COVID-19 pandemic, as social distancing is challenging in such settings. Furthermore, these populations typically lack proper sanitation and hygiene conditions, which are requirements to adequately control the outbreak. This paper proposes the use of System Dynamics modeling to support the public policy-making process in order to avert negative effects of the pandemic in the Brazilian favelas based on measures elicited from the social movement named "Favelas Contra o Corona." The simulation model assessed the effectiveness of strategies and policy bundles encompassing temporary transfer of the favela population, supply of hygiene products, emergency sanitation structures, and expansion of Intensive Care Units. Results indicate that a suitable combination of strategies can bring significant effects to the number of avoidable deaths and the availability of Intensive Care Units for the population.

Resumen Las poblaciones que viven en barrios de bajos recursos enfrentan aún más vulnerabilidades con el surgimiento de la pandemia de COVID-19, ya que para ellos el aislamiento social es una tarea difícil. Además, carecen de condiciones adecuadas de saneamiento e higiene, que son requisitos para controlar la pandemia. Este estudio propone el uso de la Dinámica de Sistemas para apoyar las decisiones de políticas públicas que leen las medidas que se tomarán para aliviar los efectos negativos de la propagación del virus basado en medidas obtenidas del trabajo del movimiento social "Favelas Contra o Corona". Se desarrolla un modelo considerando estrategias y conjunto de políticas basado en: transferencia temporal de la población de barrios de bajos recurso, suministro de productos de higiene, estructuras de saneamiento de emergencia y expansión de la Unidade de Cuidados Intensivos. Se concluye que la solamente por la combinación de políticas efectos significativos serán alcanzados en el número de muertes evitadas y en el logro de la disponibilidad de Unidade de Cuidados Intensivos en el sistema de salud.

Resumo Populações vivendo em favelas no Brasil enfrentam ainda mais vulnerabilidade com o advento da COVID-19, já que para elas o isolamento social é uma tarefa difícil. Além disso, esses locais carecem de saneamento e condições de higiene, que são requisitos importantes para controlar a pandemia. Este artigo propõe o uso de Dinâmica de Sistemas para apoiar decisões de políticas públicas relativas a medidas para aliviar os efeitos negativos da disseminação do vírus baseado em medidas definidas a partir do trabalho do movimento social "Favelas Contra o Corona". O modelo proposto avalia a efetividade de estratégias e conjuntos de políticas que envolvem: transferência temporária da população da favela, suprimento de produtos de higiene, estruturas emergenciais de saneamento e expansão de Unidades de Terapia Intensiva. Os resultados apresentam o impacto de cada uma das estratégias. Entretanto, somente a combinação adequada de medida traz resultados significativos sobre o número de mortes evitadas e à disponibilidade de leitos de Unidades de Terapia Intensiva para a população.

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RESUMEN Senecio vulgaris L. es una maleza, considerada de difícil control cuando se asocia a la zanahoria, debido a que compite por recursos con el cultivo, siendo importante su control, ya que tiene un impacto negativo en la productividad. La modelación biológica es una herramienta que permite prever los posibles efectos del control de la especie, ya que identifica las diferentes variables de un sistema y los factores que las afecta, para de este modo, predecir los resultados en diversos ambientes. Con base en la dinámica de sistemas y los aspectos morfo-fisiológicos de la especie, se planteó la modelación del banco de semillas de S. vulgaris, basado en las ecuaciones planteadas por Fernández-Quintanilla, donde se construyó el diagrama Forrester, al que se le incorporaron las diferentes ecuaciones y valores del modelo, para proyectar la dinámica de la especie en el banco de semillas, dependiendo del manejo. Se propusieron tres escenarios: (1) control con herbicidas en post-emergencia, (2) rotación de cultivos y (3) incorporar los métodos culturales de control, con un testigo en pre siembra y rotación de cultivos. Los resultados del modelo muestran que cuando se realiza rotación de cultivos y se incorporan manejos en pre-siembra al proceso convencional de la especie, se presenta una menor cantidad de semillas en el banco.

ABSTRACT Senecio vulgaris L. is a weed, considered difficult to control, when it is associated with carrot, because it competes for resources with the crop, its control being important, since it has a negative impact on crop productivity. Biological modeling is a tool that allows predicting the possible effects of the species control, since it identifies the different variables of a system and the factors that affect them, in order to predict the results in different environments. Based on the dynamics of systems and the morphophysiological aspects of the species, the modeling of the S. vulgaris seed bank was suggested, based on the equations proposed by Fernández-Quintanilla, the Forrester diagram was constructed, which was incorporated the different equations and values of the model, to project the dynamics of the species in the seed bank, depending on the management. Three scenarios were proposed, (1) post-emergence herbicide control, (2) crop rotation (3) incorporate traditional control methods with a control in presowing and crop rotation. The model results show that when crop rotation is performed and pre-sowing management is incorporated into the conventional process of the species, a smaller quantity of seeds is presented in the bank.

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BACKGROUND: Healthcare costs is one of the most studied issue in our days because of increasing demand and the aging of population. Final costs of medicines is one of the most important issue in patient treatment and determine its real value is an important task within hospitals. Simulation models and in this case system dynamics allows to build representations of reality considering the interaction of the whole variables that affect the system where first a causal loop diagram allows to represent and identify the interaction between variables for develop a stock flow diagram to determine the final results. OBJECTIVE: Develop a simulation model that allows decision makers in Hospitals and Governments to identify the variables that affect the final cost of medicines and to determine the legal reimbursement allowed by national agencies. METHODS: This paper presents a conceptual modeling framework using a causal loop diagram and a dynamic simulation model in the real case of a hospital in Colombia to explore how different internal charges for medicines affect the behavior of the final unit-dose cost of medicines, considering the complexity of the pharmaceutical system. We developed a simulation model to represent and characterize the pharmaceutical supply chain in a hospital and by using real data we validate the results of the model and conclude about the supply chain of medicines in Colombia using the legal regulations as a main factor of analysis. RESULTS AND CONCLUSIONS: We found that in some cases the maximum reimbursement value is less than the final cost of medicines within the hospital, which means that hospitals lose money on the administration of medicines to patients. The benefit of this model is that with the result the hospital can determine the real final monetary value of medicines, including the different processes starting from the reception of the medicines, ending with the administration to patients.

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The article is focused on applications of the differential inclusions to the models of economic growth, rather than the model building. The models are taken from the known literature, and some modifications are introduced to reflect an additional inertia. The aim is to treat the uncertainty in the model parameters by using differential inclusions instead of the stochastic approach. The reachable sets for the models are shown, to assess the possible ranges of the outcome with given parameters uncertainty. The approach may be interpreted as a generalization to the system dynamics methodology, providing attainable sets instead of single model trajectory and simple sensitivity analysis. A comparison with Powersim risk analysis is provided. The models of Solow and Swan, Mankiw, Bhattacharya, Romer and Weil are used. A brief review of the models is given, and several examples of simple simulations, differential inclusion applications and optimization are presented.

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Many problematic outcomes in agricultural and food systems have important dynamic dimensions and arise due to underlying system structure. Thus, understanding the linkages between system structure and dynamic behavior often is important for the design and implementation of interventions to achieve sustained improvements. System dynamics (SD) modeling represents system structure using stock-flow-feedback structures expressed as systems of differential equations solved by numerical integration methods. System dynamics methods also encompass a broader methodological approach that emphasizes model structural development and data inputs to replicate one of a limited number of problematic behavioral modes, anticipates dynamic complexity, and focuses on feedback processes arising from endogenous system elements. This paper highlights the process of SD modeling using 2 examples from animal agriculture at different scales. A dynamic version of the Cornell Net Carbohydrate and Protein System (CNCPS) that represents outcomes for an individual dairy cow is formulated as an SD model illustrates the benefits of the SD approach in modeling rumen fill and animal performance. At a very different scale, an SD model of the Brazilian dairy supply chain (farms, processing, and consumers) illustrates the country-level impacts of efforts to improve cow productivity and how impacts differ if productivity improvement occurs on small farms rather than large farms. The paper concludes with recommendations about how to increase awareness and training in SD methods to enhance their appropriate use in research and instruction.

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Although the workstations of a Brazilian automotive electrical harness production line are set close to TAKT time (the production rate required to meet demand), factory performance is compromised regarding: (i) sick leaves due to occupational disease (105 employees last year) and (ii) a production rate at only 42% of capacity. Our objective was to simulate the performance of a production line balanced against physical overload by the addition of an extra workstation. Based on ergonomic work analysis, the study applied System Dynamics at the global observation stage to obtain a systemic interpretation of the factors involved in production line performance. According to the indicators, the alternative configuration reduced physical overload by 36%, which would result in a sick leave rate of 50.8 employees/year (51.6% lower than the current configuration), as well as a production rate at 99% of capacity (a 92.7% increase over the current configuration). We found that reducing physical overload allows the "workforce control" loop to govern the system, producing favorable results. We conclude that setting the work cycle overly close to TAKT time leads to overload, due to the shorter recovery times at the end of each cycle. Thus, it is necessary to seek a balance between efficiency gains through downtime reduction and the physiological recovery of workers.

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