System Dynamics Model Research Articles

Analysis of Sea Transportation Services in Pulau Banyak, Aceh Singkil Using a Qualitative Approach

Island communities such as Banyak Island use sea transportation services as the main means of mobilization, both for work and as support to places that cannot be served by land vehicles. In addition to the local community, sea transportation services are also needed by tourists who will visit the area. This is because sea transportation is the only means that can be used to get to the island area. Currently, companies that provide sea transportation services on the Singkil mainland to Banyak Island are river, lake, and crossing transportation (ASDP) and wooden fishing boats seen pay which the island community has used for generations, and there are also fast boats that operate occasionally. The purpose of this study is to determine the condition of the availability of sea transportation for community needs fulfillment services in Aceh Singkil and Banyak Island, in addition to assessing the use of the system dynamics model with sea transportation services in Aceh Singkil and Banyak Island, and to assess the effect of sea transportation services on the economic level of the people of Aceh Singkil and Pulau Banyak. The method used in this study is a qualitative approach method. The results obtained from this study are: 1) The availability of sea transportation facilities in the future needs to be accelerated by increasing the number of sea transportation facilities serving the Singkil mainland and Banyak Island along with the increasing number of residents and visitors from within and outside the country as tourists; 2) Sea transportation services operating on Banyak Island provide a positive contribution to the local economy; and 3) To maintain the quality of sea transportation services, it is necessary to improve the existing sea transportation facilities and infrastructure.

System dynamics model for analysis of demand response on incorporating autoswitch in the Colombian electrical sector

This study investigates the potential outcomes of transforming the Colombian electricity market—70% of which is regulated—into a deregulated market. Given the impact of climate change and the need for greater control over the Colombian retail energy sector, it is crucial to examine future scenarios where two policies, successful in other countries, could improve market management. A simulation was conducted using a system dynamics model to analyze residential user behavior by manipulating demand response and implementing an autoswitch policy. The results validate the effectiveness of regulating electricity consumption through price management and the autoswitch policy, where customers can automatically switch suppliers. By 2033, these policies could reduce electricity prices by 11%–14%, depending on weather and user behavior changes, leading to significant customer savings, especially for higher-income groups, while ensuring suppliers' profitability. Although the conclusions suggest a positive outlook, the implementation of these policies requires regulatory changes and the adoption of smart energy meters. he proven policies could help Colombian government in managing consumption during energy crises.

Scenario analysis of the Indonesia carbon tax impact on carbon emissions using system dynamics modeling and STIRPAT model

This study aims to develop a system dynamic (SD) forecasting model based on the STIRPAT model to forecast the effect of an IDR 30 per kg CO2e carbon tax on carbon emissions, estimate future carbon emissions under ten scenarios, without and with the carbon tax, and estimate the environmental Kuznets curve (EKC) to predict Indonesia’s carbon emission peak. Carbon emission drivers in this study are decomposed into several factors, namely energy structure, energy intensity, industrial structure, GDP per capita, population, and fixed-asset investment. This study included nuclear power utilization starting in 2038. The research gaps addressed by this study compared to previous research are (1) use of the ex-ante approach, (2) inclusion of nuclear power plants, (3) testing the EKC hypothesis, and (4) contribution to government policy. The simulation results show that under the carbon tax, carbon emissions can be reduced by improving renewable energy structures, adjusting industrial structures to green businesses, and emphasizing fixed asset investment more environmentally friendly. Moreover, the result approved the EKC hypothesis. It shows an inverse U-shaped curve between GDP per capita and CO2 emissions in Indonesia. Indonesia’s fastest carbon emission peak is under scenario seven and is expected in 2040. Although an IDR 30 per kg CO2e carbon tax and nuclear power will take decades to reduce carbon emissions, the carbon tax can still be a reference and has advantages to implement. This result can be a good beginning step for Indonesia, which has yet to gain experience with a carbon tax that can be implemented immediately and is helpful to decision-makers in putting into practice sensible measures to attain Indonesia’s carbon emission peaking. This research provides actionable insights internationally on carbon tax policies, nuclear energy adoption, EKC dynamics, global policy implications, and fostering international cooperation for carbon emission reductions.

Enhancing Air Conditioning System Performance via Dual Phase Change Materials Integration: Seasonal Efficiency and Capsulation Structure Impact

Enhancement of the cooling and heating capabilities of an air conditioning unit (ACU) coupled with a thermal energy storage system of dual phase change materials (PCM) is investigated. The dual PCM, namely SP24E and SP11_gel, are coupled with the ACU outdoor device (condenser/evaporator) during the summer/winter seasons, respectively. Moreover, ACU performance assisted with dual-PCM heat exchanger is compared with a single heat exchanger of SP24E in summer and single heat exchanger of SP11_gel in winter at different PCM capsulation structures (aligned and staggered cylinders). The system dynamic mathematical model is computationally solved using ANSYS software and experimentally validated. Results affirm that charging/discharging periods are minimal for the dual-PCM system and slower for PCM inline cylinder layouts than staggered ones. Inline design yields greater ACU average power savings. In summer, higher inlet air temperature to the PCM system reduces PCM discharging time and ACU power savings, with the opposite effect during winter. ACU COP with PCMs is improved by around 80 % in summer and 40 % in winter, respectively, compared to ACU without PCMs. The maximum average power saving over 4 h of ACU working in summer by single and dual-PCM systems is 21.4 % and 11.8 %, respectively, whereas the results in winter are 18.5 % and 12.8 %, respectively.

Assessment and strategies for water supply security risks in the estuarine city Shanghai under normalized extreme climate conditions

Facing the escalation of extreme climate events, estuarine delta cities like Shanghai grapple with significant water supply challenges. This study employs system dynamics and dynamic adaptive policy pathways to assess Shanghai's water supply security risks and responsive strategies in 2022–2050, amidst extreme climate conditions. Utilizing data from 2000 to 2021, we constructed a system dynamics model to predict future water demand under various development modes. Focusing on the unusual 2022 drought in the Yangtze River Basin, we simulated 15 scenarios, including economy, population, water efficiency, and reservoir levels, to identify the extent and timing of potential water supply risks, then proposed pertinent dynamic adaptive strategies to address them. Our findings suggest that the 2022 drought significantly reduced Shanghai's water supply capacity, leading to a notable deficit. Under scenarios of accelerated economic growth, water supply security risks are heightened, with projections indicating a reduction of days of supply available to merely 33–67 days, and escalating water shortage amount to 592–896 million m3 by 2050. Short-to-medium-term recommendations include optimizing both local and transit water resources, strengthening emergency water reserves, enhancing water use efficiency, and maintaining stable reservoir water levels. For the long term, expanding water storage infrastructure and promoting integrated water resource management within the Yangtze River Delta is key to establishing a resilient and diversified water supply system, effectively mitigating future water security risks. This study provides a scientific basis and reference for the sustainable management of water resources in estuarine cities confronting normalized extreme climate conditions. It offers valuable insights for policymakers and actionable suggestions for urban planners.

Beyond immediate relief: Investigating multi-faceted water management in inter-basin water transfer projects

Water scarcity is a compelling and complex global challenge that has far-reaching implications for both ecological systems and human societies. In response, inter-basin water transfer initiatives have been advocated as potential remedies. Though effective in providing immediate relief, the long-term viability of these initiatives is disputed. Notably, recurring scarcity can result from increased water demand in the recipient basin due to transferred water. Addressing this requires balancing water demand and supply. Beyond supply-focused measures such as water transfers, a crucial strategy involves adopting demand-focused approaches to reduce reliance on such transfers. This study centers on the Gavkhouni basin in Iran, where despite repeated water transfers, water scarcity remains persistent due to climate fluctuations, population growth, agricultural activities, and economic development. The research developed a comprehensive system dynamic model, integrating environmental, social, and economic variables impacting water balance in the region in order to assess the effectiveness of three distinct demand-focused water management strategies, namely, technology-based, cropping pattern-based, and land-based policies, both individually and in synergy. This analysis was conducted across a set of scenarios encompassing climate change, population growth, GDP dynamics, and water transfer patterns. The findings revealed a satisfactory accuracy of the water management system model, with a 6.2% mean absolute error. In addition, findings highlighted the advantages of a multifaceted strategy, with technology-driven interventions and optimized cropping patterns emerging as particularly effective. However, the economic dimensions of these policies warrant comprehensive exploration due to the significant impact they have on the feasibility and effectiveness of the policies. The study emphasizes the need to combine demand-side policies with supply strategies like water transfers. This comprehensive approach is vital for effective water management and long-term water security.

Analysis of the Aquaponic System Sustainability via System Dynamics Modelling – FEW Nexus Approach

AbstractAquaponic systems integrate aquaculture and hydroponics, recycling nutrient-enriched water from fish tanks to grow plants, significantly reducing carbon emissions, water use and production costs compared to other methods. It is considered a sustainable solution for food production, addressing issues such as climate change and eutrophication. Particularly valuable in family farming, it increases the diversity and quality of food, while reducing its environmental impact. However, despite its potential, aquaponics lacks recognition in public policies, making its widespread adoption difficult. Quantifying its benefits is crucial for strategic planning and the formulation of policies to support family farming and the transition to sustainability, in line with global objectives. Therefore, there is a need to comprehensively quantify the benefits of aquaponics, particularly in terms of the Food-Energy-Water (FEW) nexus, to support decision-making and policy formulation for sustainable agriculture. The nexus concept encompasses highly complex systems requiring robust tools capable of analysing the interrelationships between multiple components. Aiming to analyse the degree of sustainability of aquaponics systems on family property in the FEW nexus context, a System Dynamics Modelling (SDM) coupling Socio-economic and environmental indicators was developed. The results obtained demonstrated the efficiency of using SDM as an analysis and support tool for decision-making. Additionally, they prove the environmental viability of food production via aquaponic systems.

China’s foreign direct investment: driving green growth or seeking pollution havens? Based on the perspective of green total factor productivity

China has significantly increased its foreign direct investment (FDI). Although these investments help to boost global development, their impacts on the environment are still controversial and deserve careful investigation. This paper uses the super-efficiency SBM model to measure the green total factor productivity (GTFP) of 123 host countries of China’s FDI. On this basis, we adopt the two-step system GMM and dynamic panel threshold effect model to analyze the impact of China’s FDI on the GTFP of host countries. The research results show that: 1) The impact of China’s FDI on the GTFP of host countries is mainly through green technology efficiency. Its impact is inhibitory, followed by a promotional one, with the latter being significantly larger than the former. 2) There is no evidence of the “pollution haven effect” associated with China’s FDI. In fact, for countries with lower environmental regulations, China’s FDI promotes the growth of GTFP more effectively. 3) The innovation level of host countries moderates the relationship between China’s FDI and GTFP growth. For host countries with stronger innovation level, their GTFP growth can be enhanced to a greater extent by China’s FDI.

A Systems Engineering Approach to Decarbonizing Mining: Analyzing Electrification and CO2 Emission Reduction Scenarios for Copper Mining Haulage Systems

Due to climate change risks, the public, regulators, and investors require solid actions to minimize the greenhouse gas (GHG) emissions of mineral extraction and metals production. The mining sector considers alternatives to reduce its carbon footprint by transforming the business and adopting new technologies into operations. Given the capital intensity, technical characteristics, and business structure involved, a shift in the mining industry necessitates impartial insights into the trade-offs and risks. Considering the low-carbon transition trade-offs and risks in mining, this study presents the application of system dynamics modeling (SDM) in mining projects to analyze the impact of decarbonization alternatives with respect to carbon footprint and costs. A system dynamics model of an open-pit copper mine is developed to quantify greenhouse gas (GHG) emissions, as well as capital and operational costs, during the project life cycle. The change in GHG emissions in the business-as-usual scenario with diesel equipment haulage versus the alternative scenario with electric overland conveyor haulage is compared concerning GHG emissions and associated costs. The results unequivocally demonstrated that electrifying material mobility offers significant decarbonization in open-pit mining if the on-site electricity has a low emission factor. The findings also indicate that the substantial cost difference between electrification and diesel alternatives is another major obstacle to implementing electrification in an open-pit copper mine. This research proves that implementing SDM in the mining industry can offer impartial insights into decision-making and enable a thorough evaluation of options using quantitative criteria. It effectively assesses and communicates the trade-offs and risks of transitioning to low-carbon alternatives because it analyzes project variables quantitatively and holistically and is easy to run.

The Complex Interrelationships of the Risk Factors Leading to Hamstring Injury and Implications for Injury Prevention: A Group Model Building Approach

There is a gap in the literature regarding the complex interrelationships among hamstring injury (HI) risk factors. System dynamics (SD) modeling is considered an appropriate approach for understanding the complex etiology of HI for effective injury prevention. This study adopted the SD method and developed a causal loop model (CLD) to elucidate the intricate relationships among HI risk factors. This is performed by combining literature evidence and insights from expert stakeholders through a group model building (GMB) approach. The GMB methodology facilitated the identification of sixty-five critical factors influencing the HI risk, revealing the dynamic interplay between factors. Stakeholder engagement underscored the importance of previous injury characteristics (level of influence of previous injury, severity of previous injury, quality and size of scar tissue) and the quality of rehabilitation. HI-CLD revealed that many factors had indirect effects on HI risk. The HI-causal loop model establishes a foundation for a future stock and flow quantitative SD model aiming to advance HI prevention strategies through an interdisciplinary collaborative effort. These findings underscore the complexity of HI prevention, necessitating a holistic approach that integrates the views of diverse professional expertise. Appropriate inter-professional collaboration and continuous athlete screening are important for effective injury prevention strategies.

Transition to Low-Carbon Vehicle Market: Characterization, System Dynamics Modeling, and Forecasting

Transition to Low-Carbon Vehicle Market: Characterization, System Dynamics Modeling, and Forecasting

Simulation and Regulation of High-Quality Economic Development Based on System Dynamics and DPSIR Model

Simulation and Regulation of High-Quality Economic Development Based on System Dynamics and DPSIR Model

Simulation and Prediction of Land Use Change and Carbon Emission under Multiple Development Scenarios at the City Level: A Case Study of Xi’an, China

Studying urban land use and its impact on carbon emissions is crucial for achieving China’s dual carbon goals. This research utilized the Shared Socio-economic Pathways (SSPs) scenarios 126, 245, and 585 from the Sixth International Coupled Model Intercomparison Project (CMIP6), along with a coupled System Dynamics (SD) and Patch-generating Land Use Simulation (PLUS) model and a carbon emission coefficient method to simulate and predict Xi’an’s land use carbon emissions from 2020 to 2040. The results indicate the following: (1) Cultivated and forest lands are the predominant land use types in Xi’an, with cultivated and grassland areas projected to decline under all three SSP scenarios by 2040. The most significant expansion of construction land, primarily at the expense of farmland, is projected under the SSP585 scenario, with an increase of 515.92 km2 by 2040. (2) Land use carbon emissions increased from 414.15 × 104 t in 2000 to 2376.10 × 104 t in 2020, with construction land being the primary source of emissions and forest land serving as the main carbon sink. However, the carbon sink capacity remained low at only 21.38 × 104 t in 2020. (3) Carbon emissions are expected to continue increasing under all scenarios through 2030 and 2040, though at a decreasing rate. The SSP126 scenario predicts the lowest emissions, reaching 9186.00 × 104 t by 2040, while SSP585 predicts the highest at 14,935.00 × 104 t. The findings of this study provide theoretical support for future low-carbon and high-quality urban development strategies.

Shifting wood between material and energy use: Modeling the effects of substitution

AbstractWood as a renewable material is relevant for climate change mitigation: Carbon sequestration in forests and carbon storage in harvested wood products (HWPs) contribute to carbon reduction in the atmosphere, and the substitution of carbon‐intensive products with wood products can reduce greenhouse gas (GHG) emissions. Since wood is a limited resource, it must be used efficiently and sustainably. Shifting wood from one application to another might result in decreased GHG emissions due to substitution effects. However, which wood application will lead to a GHG emission reduction is currently unknown. This study investigates the effects of shifting wood between applications and the resulting substitution effects from a system perspective. A system dynamics model describes the wood utilization system of Austria, including the value chains from the forest to wood‐processing industries and the substitution that takes place in these industries. These value chains are associated with the global warming potential. Seven wood utilization scenarios shifting between material use and use for energy are simulated. The results show that wood shifts lead to both a substitution effect (emission reduction) in industries where wood utilization is increased and a counter effect (emission increase) where wood is replaced. The two effects potentially outweigh each other partly, leading to comparatively small net effects. However, carbon sequestration in HWPs and future changes in substitution effects might lead to additional effects. To substantially contribute to climate change mitigation, alternatives other than shifting wood between material and energy value chains need to be found within the wood utilization system.

Circular battery production in the EU: Insights from integrating life cycle assessment into system dynamics modeling on recycled content and environmental impacts

AbstractThe European Union (EU) Battery Regulation aims to establish a circular battery production and sets minimum battery material recycled targets for new batteries from post‐production and post‐consumer waste batteries. However, it is uncertain whether these targets can be met due to dynamic market developments and if their compliance results in environmental benefits. Therefore, this study examines the circular battery production in the EU and its impact on material flows and the environment from a market perspective. We combined a system dynamic market model with process models for battery production and recycling, using prospective life cycle assessment. According to our analysis, the projected amount of post‐consumer waste alone may not meet the specified levels of recycled materials due to long battery lifetimes. Thereby, the targets for cobalt are particularly ambitious, with a gap of between 9.8 and 14.6 percentage points for most scenarios. In the case of reduced battery lifetimes, the achievable recycled content across all materials increases by more than 75% in 2032 and by more than 85% in 2037. The avoidance of post‐production waste leads to 9% lower greenhouse gas (GHG) emissions compared to recycling with 100% recycling efficiency. Thus, attributable amounts of post‐production waste and unfavorable prolonged use of batteries create misguided incentives to meet legal targets. Additionally, the delay between production and recycling limits the potential for circular production as this depends significantly on market conditions. Our study highlights, that besides recycling, the industry should especially advance production processes including upstream material extraction and refinement to reduce environmental impacts.

Research on Coupling Effect Measurement and Coupling Risk Simulation of Green Building Construction Safety Risk Factors

The construction of green buildings is an important direction for the transformation and development of the construction industry, but it is beset with problems such as a lack of construction experience, immature new technologies, and unstable material properties; these issues bring risks to the construction stage of green buildings, and the coupling of uncertain risk factors in the construction process of green buildings may lead to unfavorable results. The purpose of this study is to explore the coupling degree of green building construction safety risk factors and the changing trend in their coupling combinations at the system risk level. First, the risk factor index system was defined by reading the literature and gathering expert opinions, and the coupling degree between risk factors was measured using an improved coupling degree model. Then, a system dynamics model was established to simulate and analyze the coupling effects among the risk factors and determine the combinations with the greatest influence. The results show that the risk probability is proportional to the risk coupling value, the human–environment coupling value is the largest, and the material equipment–management coupling value is the smallest. The human–environment system simulation shows that reducing the coupling value of system factors will promote a decrease in the total level of system risk. According to the research conclusions, measures to prevent risk coupling are proposed, which offer theoretical references for green building practitioners carrying out risk management; these measures hold a certain guiding significance for the risk control and future development of green buildings.

Tracking and managing the water-food-environment-ecosystem (WFEE) nexus in groundwater irrigation districts using system dynamics modelling

Groundwater irrigation districts, which play a crucial role in the Earth's critical zone, are confronted with numerous challenges, including water scarcity, pollution, and ecological degradation. These issues come from multiple systems and are linked to a groundwater-dominated water-food-environment-ecosystem nexus problem related to agricultural activities (WFEE). There is a pressing need for the scientific characterization and evaluation of the WFEE nexus in groundwater irrigation districts to assure high-quality, sustainable development. Furthermore, it is critical to provide practical and efficient regulations at the farmer level to uphold the health of this nexus. This paper presents a mapping network that focuses on groundwater irrigation districts. The network aims to convert the restriction indicators utilized to maintain the health of the WFEE nexus (at the irrigation district scale) into the targets employed to manage farmers' living and agricultural activities (at the farmer scale). Additionally, a system dynamics model is created to track and manage the interacting relationships between the WFEE nexus and farmers' living and agricultural activities. This proposed model employs a structured parameter system comprising targets, state parameters, regulatory parameters, and evaluation parameters. This system can get insight into the status of the WFEE nexus at the farmer level using state parameters, induce tailored management and regulation measures using regulatory parameters, assess the effectiveness of various measures using the evaluation parameters, and finally provide decision support to enhance the health of the WFEE nexus. The findings from the research conducted in the Yong'an groundwater irrigation district demonstrated that the model accurately described the relationship between the WFEE nexus and farmers' activities in groundwater irrigation districts. Furthermore, the model responded strongly to a variety of improvement strategies, including adjustments in planting area, optimization of planting pattern, improvement of irrigation method, and implementation of agronomic measures. As a result, it provided farmers with decision support for applying agricultural management methods and addressing the WFEE nexus problem in groundwater irrigation areas.

Signal enhancement method for gearboxes fault diagnosis in robotic flexible joint

Abstract Motor Current Signal Analysis (MCSA) provides a non-intrusive approach to fault diagnosis. However, the fault impact reacting in the current is reduced due to the presence of flexible structures in the transmission path from the fault source to the motor. Therefore, this paper proposes a method to enhance the frequency domain of the current signal of a single mechanical fault through a transfer model between motor torque and link vibration. First, the joint system dynamics model was developed based on a three-inertia simplified model. The transfer model of motor torque and link vibration was defined based on the system dynamics. The link vibration is then estimated based on the transfer model and electromagnetic torque. Link vibration signal is considered as an enhancement of the torque signal. Finally, the link vibration signature analysis is performed instead of MCSA. The experimental results show that the method is effective in enhancing the features of individual mechanical faults and improving the fault diagnosis performance.

A complete shortest independent loop set algorithm for model structure analysis

AbstractThis article looks at the well‐known shortest independent loop set algorithm, which is used to identify an independent loop set in system dynamics models. It addresses the cases where the algorithm fails to find a complete set due to its limitation to geodetic cycles and introduces a modification that has the potential to identify a complete independent loop set in every case while maintaining the efficiency of the original algorithm. The modified algorithm uses second‐shortest paths to complete the loop set. Special attention is given to the creation of the second‐shortest path matrix required for the modified algorithm, and to the application of the algorithm to a model where the independent loop set created by the shortest independent loop set algorithm was previously shown to be incomplete. © 2024 System Dynamics Society.

Dynamic evaluation of distribution channels in a fresh food supply chain from a sustainability and resilience approach

Research on agrifood supply chains has grown in recent years; however, little attention has been given to the effect of the choice of distribution channel on the sustainable and resilient performance of the network. This research proposes a system dynamics model to evaluate different distribution channels for a fresh food supply chain in a developing country. Among the main results is that the use of food hubs in a channel distribution produces long-term environmental, social and resilience benefits for the entire network, while short supply chains are the most economically viable alternative.