System Dynamics Technique Research Articles

Lean manufacturing tools as drivers of social sustainability in the Mexican maquiladora industry

Social Sustainability (SOS) is crucial to an industry’s success and depends on various factors. This study presents a structural equation model (SEM) that examines how three lean manufacturing tools, focused on continuous improvement, Kaizen, Gemba, and 5Whys, can enhance SOS. Six hypotheses were proposed and validated using information from 411 responses to a survey on the Mexican maquiladora industry, and the partial least squares approach was used to test them. Subsequently, the system dynamics technique was applied to simulate different scenarios and determine the optimum SOS level based on lean manufacturing tools. The findings indicate that only Kaizen can achieve 100 % implementation within less than five years, whereas the other variables require a more extended period. Specifically, the SOS reached 100 % after 10.25 years, and this period is considered too long. Companies should periodically investigate the new needs of employees to improve their SOS. This study is the first to combine SEM and SD to assess the impact of Kaizen, Gemba, and 5Whys as LM Social Sustainability tools, offering a new perspective to achieve sustainable industrial practices. Companies should periodically investigate new employees’ needs to improve their SOS.

A Framework to Use Bifurcation Analysis for Insight into Complex Systems Resilience

AbstractThe increasing complexity and integration of systems present challenges in understanding and managing these systems, as highlighted by the INCOSE Systems Engineering Vision for 2035. This complexity risks system failures due to insufficient understanding. Resilience Engineering is a field that focuses on system behavior in the face of disruptions. However, existing methods to measure resilience, such as probability‐based measures and linear recovery models, are limited by the non‐linear and dynamic nature of modern systems. Bifurcation Analysis, a mathematical system dynamics technique, offers a different perspective by examining how systems behave under changing conditions. This approach, developed in ecology and traditionally applied in fields including power systems and neural networks, can provide insights into the resilient characteristics of non‐linear systems. Despite its promise, Bifurcation Analysis is not usually associated with Resilience Engineering. This paper proposes using Bifurcation Analysis to understand system resilience better and support Resilience Engineering practitioners. It aims to bridge the gap between the two fields, offering a framework for integrating both approaches. This framework is then applied to a model system to demonstrate its potential to enhance the understanding of system resilience. Contributions are an overview of current Resilience Engineering and Bifurcation Analysis, a general‐use framework for practitioners, and an application of this framework. Future work will focus on applying the new framework to more cases, allowing for improved Resilience Engineering, and improving the framework to make it more accessible, versatile, and reliable.

Waste Management of Construction and Demolition Materials Towards Sustainable Growth of Nagpur City

The higher amount of buildings and infrastructures in India, number of construction and demolition (C&D) waste is increasing continuously. These wastes, if not completely recycled, will create the environmental problems. This research paper concentrates on the use of a system dynamics technique to develop a C&D waste recycling. The project is based on the recycling of the rapidly increasing construction and demolition waste. Through this process we want to take a step ahead, the idea of stopping illegal Dumping and ultimately save our mother Earth from destruction. The cost of recycled C&D solid waste resulting in reduction of overall construction cost. The demolition is the most commonly pronounced word in the construction industry. As per the new building rules building should be demolished after its service period. Now-a-days the importance is given to sustainable and environmental friendly construction; there should be effective control of the demolition waste. The demolition waste can be reused for the construction. Construction and demolition (C and D) waste is defined as the solid waste generated by the construction, renovation, repair, alteration or demolition of residential, commercial, government or institutional buildings, industrial, commercial facilities and infrastructures such as roads, bridges, dams, tunnels, railways and airports. Construction and demolition waste is considered as high volume, low risk. It is commonly understood that this waste can be considered a resource, either for reuse in its original form or for recycling or energy recovery. Because of increasing waste production and public concerns about the environment, it is desirable to recycle materials from building demolition. If suitably selected ground cleaned appropriate industrial crushing in plants, these materials can be profitably used in concrete. Despite this, most Construction and Demolition waste ends up in landfills recycled aggregate and recycled sand that can be obtained. Further with the help of the obtained recycled material we intend to make various products such as concrete, paver blocks, hollow blocks, etc which will in turn be less costly as well. These recycled materials and products made from it are economical without any considerable change in the strength and durability aspect. Not only the cost effectiveness but it will also be aesthetically pleasing. According to Metropolitan region development authority the amount of construction and demolition waste (C&D waste) must be reduced by at least 70%. 3Rs model (Reduce, Reuse and Recycle) in the C&D waste management with costs savings. This paper finds a broader understanding of the socioeconomic implications of waste management over time and the positive effects of these policies in the recycled to achieve the goal of C&D waste as well as the composition of Construction and Demolition waste, the need for its recycling and options that can be implemented for its efficient use in the field of concrete technology. Key Words: C & D waste; sustainable construction systems, Recycling, Concrete.

Effect of Training on the Construction Project Performance Using System Dynamic

The sector of construction is important for the country's economic, community, and ecological agendas and therefore takes an important role in Iraq's future; managers of the project are in charge of activities planning and coordinating, and at the same time, obtaining the best charge, period, resources of the human and material so that objectives of the predetermined project are finally gotten. Hence, it is productivity can be increased if the skills of the managers of the projects are improved the paper aims to determine the effect of training on the project's performance in terms of both time and quality to obtain the causal effect on the projects. The paper's methodology consists of a questionnaire distributed to 140 experts in different sectors to obtain the problem that affects the time and quality of the projects and then analyze these problems using the system dynamic technique. Depending on the effort of the research, the subsequent assumptions can be utilized: The training system in Iraqi construction is very weak and very negligible and doesn't contain any supervision Most of the engineers are not multidiscipline, and even if they work on the other discipline, the luck the principle of it. The nature of the construction industry in Iraq tends to use traditional methods in construction and refuses to use modern techniques. There are a series of shortages in communication between different disciplines and that creates a gap that leads to becoming an obstacle in the front of project completion.

Modeling for a Sustainable Electricity Supply in Uzbekistan

For nations to achieve mobility as well as economic and social growth, a steady supply of electric power is crucial. Investments in capacity building and raising operational standards are necessary for the reliability and consistency of the delivery of electricity. A decision-making in the sector has become difficult for investors and policymakers, due to challenges associated with the electricity sector including delays in generation and infrastructure construction, R&D, natural gas supply, fluctuations in demand and environmental concerns. Additionally, the power sector is dynamic and perpetually changes overtime. Electricity supply and demand is highly complex and dynamic in Uzbekistan. Understanding the causal linkages between major system variables that exist Uzbekistan’s electricity system is crucial for making systematic and long-term policy decisions. This work proposes a computer simulation model based on system dynamics technique. The simulation outcomes revealed that investments in power generation capacity and efficiency enhancement are required in the country to provide a sustainable electricity.

Assessing the Impacts of Climate Change on Water Resources Carrying Capacity Using Venism

Purpose: Climate modification and population increase are threatening water supplies. The world's population have tripled ever since the turn of the century, nonrenewable energy demand has climbed by a ratio of 30, while occupational production had also risen by a ratio of 50.
 
 Theoretical Framework: Problem sizing and structure, model conceptualization, model implementation and testing, and scenarios analysis are the four phases of a conventional SD modeling framework.
 
 Methods: This indicates that as a result of occupational, agricultural, and urban usage, there is a rising demand for water and a diminishing supply of resources of sufficient quality. Due to the effects of climate change, unkind ocean smooth rose by 0.19 m among 1901 and 2010. Anthropogenic climate change is known to have impacted the incidence and magnitude of flooding. Globally, the recent identification of growing vogues in precipitation and large flows in specific basins suggests a larger impact.
 
 Results: This research article takes stock of the evaluation of the influences of climate change on water transport capacity, in particular using the Vensim model. In this research review, for the analysis or estimate of the impacts of climate change on the water transport capacity, Vensim was investigated using a system dynamics technique to simulate the basin slopes of the supply systems to study climatic effects.
 
 Conclusions: It was concluded that the combination of different adaptation strategies, such as desalination, the construction of dams and the promotion of water conservation, has the greatest effects in reducing the impacts of climate change.

The viable system model and the viability theory: Collaborations paths

The cybernetic viable system model (VSM) and viability theory (VT) are based on common assumptions. Both are tools for understanding and designing organizations. What, then, are the specific notions or concepts they share? What are their points of contact? To answer these questions, we identify the various mathematical concepts of control theory used in VSM and study the advances made in VT. We also summarize the various concepts in each approach. It is shown that VSM emphasizes general structures whereas VT puts the accent on the behaviour of particular dynamic systems. Our general conclusions are that: (1) VSM contributes important cybernetic concepts while VT provides precise notions of tychastic viability, viability and invariant sets as well as capture and absorption basins; and (2) control theory strongly enriched by system dynamics techniques is the most important theoretical and practical bridge between VSM and VT. These various characteristics of the two methods lend themselves to fruitful collaboration between them and form the basis of an attractive agenda for further research.

A framework for the evaluation of the decision between onsite and offsite construction using life cycle analysis (LCA) concepts and system dynamics modeling

The decision to choose between onsite and offsite construction is important in the effort toward sustainable construction. Offsite construction is often promoted as an environmentally friendly approach to construction operations. However, previous studies have shown that there is a lack of clarity on the environmental trade-offs between onsite and offsite construction. Factors that can affect the decision to build onsite or offsite include the availability of a local offsite manufacturing facility, the distance of the offsite factory to the final place of use, the proximity of the site to the local supply of material and labor, etc. This study provides a framework to apply the system dynamic modeling technique to evaluate how various factors can affect the environmental impact of the building construction phase (for onsite or offsite construction methods). The system dynamic model (using Vensim software) that was developed provides a platform that allows users to input variables such as the distance that is expected for transportation of labor, material, and equipment to both the onsite facility and the offsite construction location, factors associated with the use of equipment for construction, the distance needed for transportation of building panels or modules from the offsite facility to the final site, etc. Among other things, the model showed that an increase in the distance from the offsite yard to the final construction site increases the total impacts of transportation of completed modules. An increase in the number of trips for the transportation of material to the onsite construction location increases the total impact of onsite construction. In terms of the environmental impact of construction, none of the two methods of construction gives an absolute superiority over the other. The environmental performance of offsite and onsite depends on various associated factors. It is recommended that building practitioners review various factors that are peculiar to their projects to make an informed decision on the best construction methods.

Mathematical Modelling of Combined Intervention Strategies for the Management and Control of Plasma Glucose of a Diabetes Mellitus Patient: A System Dynamic Modelling Approach

With the rapid increase of diabetes mellitus cases in the world, management and control of the disease has become a complex and highly dynamic process. This challenge requires a multifaceted approach to manage and control the complications associated with the hyperglycaemia or hypoglycaemia conditions. This paper presents a mathematical model for determining the influence of combined intervention strategies in the management and control for the plasma glucose of the type II diabetes. System dynamics (SD) techniques were used in modelling the sub-compartments of biological systems of an Identifiable Patient (IP). The system dynamic model developed gave an illustration on how typical glucose-insulin dynamics occur at different intervention strategies involving varying amounts of carbohydrates taken, intensity of physical exercises, stress levels and the amount of exogenous insulin administered. The model was conceptualized within a semi-closed loop system representing the patient ecosystem by extending the Bergman Minimal Model. Stochastic differential equations (SDE) were used to capture the non-linear, continuous time varying interactions of the measurements associated with plasma glucose-insulin dynamics. The estimated results from the model showed combined intervention strategies of reduced amounts of carbohydrates intake, reduced stress levels and varying moderately high-to-low exercise intensity at a constant unit of exogenous insulin produced good plasma glucose levels control.

Develop a Smart Microclimate Control System for Greenhouses through System Dynamics and Machine Learning Techniques

Agriculture is extremely vulnerable to climate change. Greenhouse farming is recognized as a promising measure against climate change. Nevertheless, greenhouse farming frequently encounters environmental adversity, especially greenhouses built to protect against typhoons. Short-term microclimate prediction is challenging because meteorological variables are strongly interconnected and change rapidly. Therefore, this study proposes a water-centric smart microclimate-control system (SMCS) that fuses system dynamics and machine-learning techniques in consideration of the internal hydro-meteorological process to regulate the greenhouse micro-environment within the canopy for environmental cooling with improved resource-use efficiency. SMCS was assessed by in situ data collected from a tomato greenhouse in Taiwan. The results demonstrate that the proposed SMCS could save 66.8% of water and energy (electricity) used for early spraying during the entire cultivation period compared to the traditional greenhouse-spraying system based mainly on operators’ experiences. The proposed SMCS suggests a practicability niche in machine-learning-enabled greenhouse automation with improved crop productivity and resource-use efficiency. This will increase agricultural resilience to hydro-climate uncertainty and promote resource preservation, which offers a pathway towards carbon-emission mitigation and a sustainable water–energy–food nexus.

Simulation of chain of tanks to augment water supply: a case study from Tamil Nadu

Abstract The application of system dynamics techniques is gaining significance and is much needed for an effective management of the depleting water resources in a dynamically complex region and considers it as the feedback from the system. The present study deals with the application of a system dynamic approach to simulate a chain of four tanks in the Guduvanchery watershed, Tamil Nadu, India. Standard data-driven models cannot be effectively used due to a lack of quality data for ungauged basins. VENSIM was used for the system dynamic simulation to assess water availability for the sustainable management of water resources. Inflow into the four tanks, net losses in each tank, and crop water requirement were given as inputs into VENSIM. Along with different models, an extensive field survey was carried out to quantify each input component. Based on system dynamics simulation, only 28% of the total available water is used for irrigation and the rest is wasted due to evaporation, transition loss, and spill from the tanks. It was found that there was approximately 5.46 MCM of surface water available in the watershed, and it will be able to supply the domestic demand of the watershed of 0.672 MCM in addition to the irrigation requirement.

Enhancing the decision-making process for public-private partnerships infrastructure projects: a socio-economic system dynamic approach

Public-private partnerships (PPP) have many critical socio-economic concession variables that need to be determined during the negotiation of the PPP contracts. However, their determination presents complexities to decision-makers due to these components’ interdependencies. Assessing the dynamic and interdependent relationships between the socio-economic concession components can enhance the development of PPP concessions. System dynamics (SD) techniques have provided a holistic system understanding of several complex structures from a holistic perspective. This paper aims to build a novel socio-economic SD model to facilitate the decision-making process for PPP projects via determining and assessing the adequate concession period, concession price (user-payment), government subsidy, and the capital structure (in the form of equity). A case study for a PPP toll-road project (I-4 Ultimate) is utilized to validate the proposed model’s results. Higher concession prices increased net present value (NPV) levels and PPP effectiveness. Simulation results showed that the variables are interdependent, and a change in the value of one variable will lead to a change in the values of the other variables. The results also showed that the concession price (user-payment) has a major influence on the concession variables. The model proposed in this study gives a holistic perspective of the complex interplay between PPP effectiveness and several socio-economic variables and is potentially valuable in facilitating and enhancing the decision-making process for PPP projects. While many scholarly discussions have been fronted on the use of system dynamics modeling in PPPs, the specific and unique combination of concession variables is the ultimate contribution of this study to the existing body of knowledge.

Embedding sustainable land-use optimization within system dynamics: bidirectional feedback between spatial and non-spatial drivers

In this paper, a space-time model is developed to support spatial planning. The temporal nature of the model allows the variables that condition land use to evolve periodically. In each time-step, land use allocation is optimized considering sustainability criteria. The model combines system dynamics techniques to simulate the evolution and interactions of economic and biophysical drivers using a multi-objective algorithm for spatial optimization that introduces bidirectional spatio-temporal feedback. It provides sets of maps for decision makers in which income and food self-sufficiency are maximized and the environmental impact of different what-if scenarios is minimized. The model has been applied in Los Llanos de San Juan (Mexico) for three scenarios: baseline, high and sustainable growth. The maps obtained by 2050 reduced water demand pressure by 1.4% and 4.7%, while crop production (in calories) was balanced with population food needs in 2035 and 2045 in the high and sustainable growth scenarios, respectively.

System Dynamics Modeling Of Relief Logistics

Earthquake crisis management is a continuous process that includes pre- and post-earthquake measures, and are in needs of integration. The optimization models that have been presented in the literature, due to the large dimensions of the model and the existence of computational constraints, only one phase of the earthquake crisis have considered and hence security, cultural, and social constraints are not taken into consideration. In the proposed model using system dynamics technique, an integrated model is introduced. Influential factors were identified through review of past research and interviews with experts. Aftre developing cuasal diagram and the stock and flow diagram mathematical modeling of the problem were in order. Once the simulation of model using Vensim software was satisfaction scenario analysis were started. If the values of the variables after the crisis are optimal, the value of the variable “Coorporation and coordination between the parties involved” improves by 85% and the value of the variable “Organizational Performance “improves by 63%. However, if the values of the variables before the crisis are in the optimal state, the mentioned values will increase by 89% and 86%, respectively. When the values of the model before and after the crisis are simultaneously optimal, the values of these variables will increase by 98 and 160 percent, respectively. The proposed integrated model includes forecasting risk and preparations in the first phase while at the same time considers actions during the earthquake phase and then in the response phase. These all together are causing to develop a model in an optimal way. The effect of training on improving the performance of the healthcare network can also be seen.

Management of agricultural saline drainage using system dynamics approach

AbstractAgricultural drainage water quality changes over time until it reaches a balance. In areas with shallow and saline groundwater, it might take several years to reach a balance. In such cases, knowledge of the quantity and quality of drainage water is necessary to manage it. The drainage water generated must then be managed for reuse purposes where it is of suitable quality and is finally discharged or disposed of. In this paper, the system dynamics technique was used to manage this drainage water. The study used the system dynamic programming tool VENSIM. The model developed in this study is capable of managing drainage water by combination of existing solutions such as mixture of irrigation water, used for downstream and cultivation of salt tolerant plants, used for irrigation of salt‐friendly plant, discharged into a river and discharged to evaporation ponds, simultaneously. The model was run using actual data for Khuzestan Province of Iran. The results showed that the model could be an opportunity for the design and management of drainage systems.

System Dynamics framework for tourism development management

ABSTRACT Tourism management requires an understanding of the structures that govern the behaviour of the Tourism system and its development. Despite the strong growth of this activity in recent decades, studies in this regard are still below needs. In this context, the purpose of this paper was to investigate the cause–effect relationships between variables related to Tourism development using the System Dynamics technique. A bibliographic research was carried out to provide empirical evidence for the construction of the model. The result presented is a Causal Loop Diagram composed of seven units in dynamic interaction: tourists, natural and cultural resources, attractions (attractiveness), infrastructure and superstructure, Tourism services and equipment, Tourism demand (market) and competitive rivalry (market). The microenvironment and macroenvironment of the system were also highlighted. The results show that the pattern of Tourism Development Dynamics, with two dominant loops conjugated in negative feedback, follows the behaviour of an S-Shaped Curve. However, this behaviour can be altered by the influence of infrastructure and superstructure on natural and cultural resources.

Risk assessement of Vietnam construction project: System dynamics model approach

There are some papers carried out for risk assessment of construction projects. However, several shortages of this research have been identified, including the usage of inappropriate techniques for assessing risk when they are unable to simulate the relationship of potential risk variables. Therefore, the application of modern qualitative and quantitative methods considering the interaction, independencies, and feedbacks among project risks is extremely necessary. This paper aims to introduce a comprehensive technique for risk assessment through approaching system dynamics (SDs) technique. The application of the SDs model will help project managers model the magnitude of the impact of the risks on cost, time, and quality of the project based on the complex interaction of these risk variables.

Moderating Effect of Audit Quality on the Relationship Between Board Characteristics and Audit Report Lag of Listed Non-Financial Companies in Nigeria

This study examined the moderating effect of audit quality on the relationship between board characteristics and audit report lag of listed non-financial companies in Nigeria. The ex-post facto research design was adopted, secondary data was extracted from annual reports and accounts of thirty-one listed non-financial companies for six years (2013-2018). Data were analyzed using system dynamic panel-data estimation technique; the findings revealed a negative and significant effect of board size on audit report lag, board independence has a positive but non-significant effect on audit report lag, however, board meeting has a positive and significant effect on audit report lag. Besides, audit quality has a negative and significant moderating effect on the relationship between board characteristics and audit report lag of listed non-financial companies in Nigeria. The study concludes that audit quality moderates the relationship between board characteristics and audit report lag of listed non-financial companies in Nigeria and recommended strict adherence to regulatory guidelines to avoid regulatory fines. Keywords: Audit Quality, Board Characteristics and Audit Report Lag DOI: 10.7176/RJFA/12-8-06 Publication date: April 30 th 2021

Using participatory system dynamics modelling to quantify indirect land use changes of biofuel projects

ABSTRACT The use of biomass to produce biofuels can lead to both direct and indirect Land Use Change (LUC). While the causes underlying LUCs are complex their quantification is a scientific challenge that hinders decision-making. Here we demonstrate the application of participatory modelling in combination with System Dynamics techniques to the analysis of the land-change dynamics associated with biofuel supply chains. The ambition is to provide decision-makers with useful and credible knowledge of direct and indirect LUCs. We illustrate the application of the approach by applying it to a real‐world project for the production of advanced biofuels in Sardinia (Italy). The results show that the land use displacements vary in intensity and persistence depending on the crop management regime applied and the future development of the market of sheep cheese. The results were considered credible by actors with direct knowledge of the ‘real’ system and useful by decision makers .

Análise e simulação da gestão da produção de empresa: uma abordagem de dinâmica de sistemas

No âmbito da gestão da produção, devido à sua complexidade e dinamicidade, os gestores e demais tomadores de decisão devem planejar a produção e analisar o processo produtivo de forma efetiva e minuciosa. A fim de auxiliar no processo de tomada de decisão, existem diversas técnicas de modelagem e simulação de processos. Neste trabalho, o objetivo foi modelar e simular a gestão da produção em uma empresa que fabrica produtos ligados à comunicação visual com foco em produção para estoque, por meio da técnica de dinâmica de sistemas. Inicialmente, o modelo foi validado utilizando-se dados históricos e, posteriormente, simularam-se o cenário base e mais três cenários a fim de verificar o comportamento do sistema diante da redução do estoque desejado e do aumento da previsão de vendas. Concluiu-se que a análise e simulação da gestão da produção da empresa por meio da técnica de dinâmica de sistemas é viável e relevante para auxiliar os gestores na definição dos planos de vendas, estoque e produção e na identificação do impacto dos gargalos produtivos no sistema. Concluiu-se, ainda, que a atual capacidade produtiva da empresa analisada atende de forma satisfatória sua atual demanda.