System Dynamics modelling

Recently, there have been Indonesian students who chose to study abroad with various initial intentions in increasing numbers. However, from the viewpoint of future national development it is feared that students finally may choose to stay abroad rather than to go back to Indonesia and to contribute to developing their homeland. Not only for students but also for professionals, especially specialists and engineers, feel more desirable to work in developed countries rather than their homeland. Although this phenomenon is not conspicuous, it is very significant to Indonesia. This study aims to grasp the general situation of 'Brain Drain' in Indonesia, to explain the 'Brain Drain' process by constructing a System Dynamics model, and to estimate the effects of government's policies by simulations under a variety of policy scenarios. Two main methodologies are used in this study. First is the use of descriptive statistics. The second methodology is application of System Dynamics (SD) to social model building. The questionnaire results suggest that 'education' factor is the most influential for respondent's decision on where to live; then followed by 'economy', 'social', 'environment', and 'politics' factors. The results also indicate that most of respondents' occupations are students. Second, according to the data gathered for calculating the correlations between factors, 'economic' indicator is considered as the core factor because it has high correlations with other factors except for 'social' indicator. Three mixed policy scenarios are selected for simulation and showing the most optimal policy scenario by comparison with the base scenario: (1) education and economy; (2) social and education; and (3) politics and economy. The result of simulations shows that each mixed policies has its own impact in different aspects because it has different characteristics and concentrations, hence it depends on the government which scenario to follow. .

Over the past two years OLM Consulting, initially in partnership with Cognitus, have used system dynamics modelling in a wide range of health and social care settings to shed light on a number of difficult and complex issues. A related paper presented to this conference (Using System Dynamics to Influence and Interpret Health and Social Care Policy in the UK) describes the experience of introducing System Dynamics in a public service setting.

Omni-directional mobile platforms have the ability to move instantaneously in any direction from any configuration. As such, it is important to have a mathematical model of the platform, especially if the platform is to be used as an autonomous vehicle. Autonomous behaviour requires that the mobile robot choose the optimum vehicle motion in different situations for object/collision avoidance and task achievement. This paper develops and verifies a mathematical model of a mobile robot platform that implements mecanum wheels to achieve omni-directionality. The mathematical model will be used to achieve optimum autonomous control of the developed mobile robot as an office service robot. Omni-directional mobile platforms have improved performance in congested environments and narrow aisles, such as those found in factory workshops, offices, warehouses, hospitals, etc.

Volume 23, Issue 2, Pages 87-172 (February 2005) 10. Harrison, Frederick, Lock, Dennis, Advanced project management -a structured approach fourth ed., Gower Publishing Limited; 2004, 315 pages, ISBN 0-566-07822-8, £67.50. Pages 169-171 Garth G.F. Ward 11. Alan Webb. The Project Manager's guide to Handling Risk. Gower, Aldershot, 2003, Hardbound 179 pp. £55.00, ISBN 0 566-08571-2. Page 172 Steve Simister

This work presents the modeling, small-signal stability analysis, and control problems of a microgrid being implemented in Fortaleza, Brazil. The methodology used to obtain the linearized model of the microgrid is based on the model developed in Rese (2012). The result of this application is the validation under realistic platform of the work developed in the referred dissertation, and of the microgrid structure being mounted. This validation is done by checking its dynamic behavior, operating in both grid-connected and in islanded modes and its small-signal stability. The load flow results for operation in islanded and grid-connected modes are presented considering the periodic availability of intermittent sources and the possibility of exporting electricity to the electric power system. In addition, the methodologies used for the voltage source inverter controllers design, and the relationship between theoretical models and practical structures are detailed, focusing on the mathematical model used for modeling the microgrid and the test system used.

Dissolved salts in seawater or brackish water are reduced to a potable level through separation techniques, like, distillation, multiple effect vapor compression, evaporation, or by membrane processes such as electro-dialysis reversal, nano-filtration, and reverse osmosis (RO). RO is the most widely used desalination process. Recent advances in RO technology has led to more efficient separation and now is the most cost effective process to operate. The performance of the reverse osmosis process is dependent on concentration of dissolved solids in the feed-water, feed-water pressure, and the membrane strength to withstand system pressure, membrane solute rejection, membrane fouling characteristics, and the required permeate solute concentration. RO is a promising tool that uses cellulose acetate (or) polyamide membrane and is widely chosen as the cost of production is reduced by the use of energy efficient and process control techniques. This paper presents a review on modelling, identification of parameters from single input-outputs and multi input/output lumped systems, dynamic modelling and control of desalination systems in the past twenty years by collecting more than 60 literatures.

This paper presents a system dynamics (SD) approach for the analysis of the demand amplification problem, also known as the bullwhip effect, which has been studied fairly extensively in the literature. The construction of an SD model is reported using a part of a supermarket chain system in the UK as an example. Based on the model, the causes of the dynamic behaviour of the system and the sources of amplification from the downstream to the upstream of the chain are investigated. The impact of information delays, demand forecasting and information sharing on the performance of the multi-echelon supply chain is analysed. Some implementation issues are also addressed based on the simulation analysis.

Small ruminants are important assets in several regions of the world. They account for more than half of the domesticated ruminants. Despite the growth in goat production in the world (more than 2% per ye. ar), research related to goat production is less than desired. One underused but potentially valuable approach for research on small ruminants is sim ulation modelling. Models of the components of small ruminant systems can enhance the financial returns and reduce negative environmental impacts. These models can be used to assess many dimensions of small ruminant production, from rumen dynamics to economic policies designed to support small ruminant production. Understanding the nutrition, pro duction, and economic policy feedback signals and planning ahead is crucial to build a robust and integrated production activity that can be managed under different production scenarios. System Dynamics (SD) is a computer-aided modelling methodology that can be used to perform policy analysis and decision support system (DSS) applied to dynamic problems arising in complex social, managerial, economic. or ecological dynamic systems characterized by interdependence, mutual interaction, information feedback. and circular causality. SD can be used as a modelling tool to aggregate knowledge to solve d ifferent types of problems that have a limited scope to a specific location or have broad trends of applications across locations and areas of science. Important issues of broad application include the bearings ofanimal production in the climate change and the impacts of climate change in animal production, alternative production scenarios ofanimal and crop integra tion, associations between animal production and business (economics, marketing). The trend of increasing small ruminants in tropical and subtropical regions and an increasing pressure on tropical and subtropical livestock systems to produce food, to feed livestock. and to produce energy crops warrants the development ofDSS to address issues such as what is the "real" benefits of livestock. the negative impacts livestock can have on greenhouse-gas emissions and the environment, and the effects ofclimate change on livestock systems.

Over the past two years OLM Consulting, initially in partnership with Cognitus, have used system dynamics modelling in a wide range of health and social care settings to shed light on a number of difficult and complex issues. A related paper presented to this conference (Using System Dynamics to Influence and Interpret Health and Social Care Policy in the UK) describes the experience of introducing System Dynamics in a public service setting.

The MacArthur-Wilson equilibrium theory of island biogeography has been one of the more influential concepts in modern biogeography and ecology. In this paper, we synthesize the theory and examine effects of different immigration/extinction rate-species diversity curves on original predictions from the theory by using the System Dynamics simulation modeling approach. Moreover, we develop a comprehensive and generic System Dynamics model to incorporate a variety of recent modifications and extensions of the theory, including area effect, distance effect, competition effect, habitat diversity effect, target effect, and rescue effect. Through computer simulation with STELLA, a more profound understanding of the theory of island biogeography can be gained. The System Dynamics modeling approach is especially appropriate for such a study because it maximizes the utilization of the ecological data by incorporating qualitative information so that a complex, imprecisely-defined ecological system can be studied quantitatively, effectively, and comprehensively.

Energy planning techniques are essential tools in the management of new complex energy systems. Among different techniques, System Dynamics is an appropriate technique for the simulation of complex energy systems and the analysis of their dynamism. In this paper, a regional dynamic integrated electricity model (RDIEM) is developed for a regulated electricity supply system in order to analyze the results of different scenarios and policies and find the right policies for the electricity generation. The results of model are validated with a real case in the province of Yazd in Iran. The results show that the balanced growth and the environment-oriented policies have the best results among different policies. Although the application is related to the Iranian case, the implications are much wider, especially in the Middle East.

This paper addresses the optimal schedule of a resource constrained four-batch digester system of an industrial acid sulphite pulp mill. This involves the development of two different models, one to model the scheduling operational problem and the other the batch digester operation-process model. The first model uses a discrete-time Resource Task Network (RTN) based representation leading to a Mixed Integer Linear Program (MILP) formulation. In this, the main operational limitation, steam availability, is modelled through the definition of a superstructure including the most relevant heating alternatives. The duration of the generated heating tasks was estimated through the use of the process model-a distributed heterogeneous dynamic model in gPROMS, with a heat-transfer resistance at the solid-fluid-interface-validated with experimental plant data. The optimal schedules obtained showed that an increase in the total available steam from the boiler is vital to allow a higher level of productivity and that not much can be done regarding steam sharing improvements.

Abstract: With ongoing differentiation of society and an increasing demand to consider sustainability principles, instruments to support the assessment, design and control of complex socio-technical systems will gain importance. In this context, computer-based numerical models may play an essential role. We present a system dynamics based simulation system for plastics waste management and discuss the practical experiences made with this system. The simulation system–called EcoSolver IP-SSK-combines the ...

A) Social  Systems                                                      2
B) Modelling                                                                3                 
C) Mental Models and Computer Simulations      4
D) Complex Systems behave Counterintuitive 5
E) Goals of Social Systems and Models                  6
F) Learning by Modelling and Smulations 7
G) Links to my papers from J.W. Forrester in www.academia.edu ...  8

This book explains how Interpretive Structural Modeling (ISM) can be used as a suitable method to depict relationship between elements to generate systemic model in tourism and agriculture.
The book is consisting of four parts. In the first part, there are background of the study, objective of the study and the benefits of the study. 
In the Part Two, Concept and Method will be explained.  Regarding the CONCEPT, overview of Interpretive Structural Modeling (ISM) will be clearly focussed including Stages in Undertaking the ISM, detail explanation about Key Factors of ISM, and previous studies on using ISM approach.  This part will also have supported by an overview of Systems Thinking, Sustainable Tourism and Challenges of Local Agricultural Products in Sustainable Tourism.  Regarding the METHOD, Research Location and Period of the Research will be explained followed by Respondents (Experts), Data Analysis, and Constructing Elements as well as Limitations of Interpretative Structural Modeling.
In the Part Three, RESULTS AND DISCUSSION will be clearly explained,  Finally, Conclusion and Suggestion for further study can be found in the Part Four.

For more than 50 years, Colombia has suffered from internal conflicts between the government and different armed groups (guerillas, paramilitary forces, drug lords, private armies). Since last year, the negotiation process between the main guerilla group (FARC) and the government has defined a broad 6-topic agenda which hopefully will lead to a peaceful end of war. A key component that must be addressed for the success of this negotiation is the development of public policies regarding the reparation of the victims of this conflict.
This paper focuses on evaluating possible tools that can be used to support the challenges related to the planning and assessment of the required resources for the implementation of a comprehensive policy towards the displaced population. We argue that the use of simulation tools and methodologies such as system dynamics can be an effective approach to learn about the effectiveness of those policies.
Any policy aiming to provide compensation or other reparations to victims of forced displacement (almost ten per cent of the whole population of the country) needs to be carefully crafted, as elements such as the information delays, feedback cycles, and other characteristics related with this situation could provide more challenging without the aid of a planning tool as such. We build a preliminary simulation model exemplifying the implementation of a policy aiming to repair victims from forced displacement in Colombia comparing the prescribed terms defined by law, as opposed to the real lapses that the process is taking into practice. We argue that, assessing the requirements and the limitations of the restitution of land in Colombia in a simulation environment will be a useful tool to learn about the challenges and inform policies in this extent.

Globalisation, increasing complexity, and the need to address triple-bottom line sustainability have seen the proliferation of Learning Organisations (LO) who, by definition, have the capacity to anticipate environmental changes and economic opportunities and adapt accordingly. Such organisations use system dynamics modelling (SDM) for both strategic planning and the promotion of organisational learning. Although SDM has been applied in the context of tourism destination management for predictive reasons, the current literature does not analyse or recognise how this could be used as a foundation for an LO. This study introduces the concept of the Learning Tourism Destinations (LTD) and discusses, on the basis of a review of six case studies, the potential of SDM as a tool for the implementation and enhancement of collective learning processes. The results reveal that SDM is capable of promoting communication between stakeholders and stimulating organisational learning. It is suggested that the LTD approach be further utilised and explored.

This paper presents the development of a system dynamic model to simulate and analyze desertification. The human-environment coupled model integrates socioeconomic drivers with bio-physical drivers of biomass production, land degradation and desertification. It is based on the UN and GEF definitions of desertification. It illustrates the concept of desertification through differential equation and simulation output graphics. It is supplemented with a causal loop diagram demonstrating the existing feedback mechanisms. The model relates population pressure and dynamics over time to the growth and availability of biomass resources. The human population stock is described as a function of growth rate, death rate and resources dependent in and out migration of people. The relative growth rate of the stock of resources is modeled as a function of climate and exploitation pressure affecting soil erosion and water availability. The model is applied for the Sahelian desertification syndrome using input data to illustrate and simulate a 150 years period (1900-2050) in Kordofan, Sudan. The model indicates that it is difficult to generate irreversible desertification.

This paper reports the results of a review of simulation applications published within peer-reviewed literature between 1997 and 2006 to provide an up-to-date picture of the role of simulation techniques within manufacturing and business. The review is characterised by three factors: wide coverage, broad scope of the simulation techniques, and a focus on real-world applications. A structured methodology was followed to narrow down the search from around 20,000 papers to 281. Results include interesting trends and patterns. For ...

Research on the post-occupancy stage of buildings is receiving growing interest due to the need to significantly reduce energy consumption and CO2 emissions and therefore make buildings more sustainable. The interrelationship between the building occupants (socio), the systems put in place (technical), and the building itself (technical) has added more pressure to this issue of sustainability. Building performance is therefore

Mathematical models of molecular networks regulating biological processes in cells or organisms are most frequently designed as sets of ordinary differential equations. Various modularisation methods have been applied to reduce the complexity of models, to analyse their structural properties, to separate biological processes, or to reuse model parts. Taking the JAK/STAT signalling pathway with the extensive combinatorial cross-talk of its components as a case study, we make a natural approach to modularisation by creating one module for each biomolecule. Each module consists of a Petri net and associated metadata and is organised in a database publically accessible through a web interface (www.biomodelkit.org). The Petri net describes the reaction mechanism of a given biomolecule and its functional interactions with other components including relevant conformational states. The database is designed to support the curation, documentation, version control, and update of individual modules, and to assist the user in automatically composing complex models from modules. Biomolecule centred modules, associated metadata, and database support together allow the automatic creation of models by considering differential gene expression in given cell types or under certain physiological conditions or states of disease. Modularity also facilitates exploring the consequences of alternative molecular mechanisms by comparative simulation of automatically created models even for users without mathematical skills. Models may be selectively executed as an ODE system, stochastic, or qualitative models or hybrid and exported in the SBML format. The fully automated generation of models of redesigned networks by metadata-guided modification of modules representing biomolecules with mutated function or specificity is proposed.

The complex structure of construction project risks arises from their internal and external interactions with their dynamic nature throughout the life cycle of the project. A system dynamics (SD) approach to construction project risk management is presented, including risk analysis and response process. Owing to the imprecise and uncertain nature of risks, fuzzy logic is integrated into system dynamics modelling structure. Risk magnitudes are defined by a fuzzy logic based risk magnitude prediction system. Zadeh's extension principle and interval arithmetic is employed in the SD simulation model to present the system outcomes considering uncertainties in the magnitude of risks resulting from the risk magnitude prediction system. The performance of the proposed method is assessed by employing the method in the risk management plan of a sample project. The impact of a sample risk is quantified and efficiency of different alternative response scenarios is assessed. The proposed approach supports different stages of the risk management process considering both the systemic and uncertain nature of risks.

Improving the efficiency of water allocation has long been recognised as a key problem for the water resources management decision-makers. However, assessing the efficacy of management decision is difficult due to the complexity and interconnectivity of water resource systems. For this reason, it is vital that robust modelling approaches are employed to deal with the feedback loops inherent in the water resource systems. Whilst many studies have applied modelling to various aspects of water resource management, little attention has been given to innovations in modelling approaches to deal with the modelling challenges associated with improving decision-making.

, devoted to the topic of 'Rationality in System Dynamics: Modelling Human and Organizational Decision Making'. This edition of Systems Research and Behavioral Science is devoted to the presentation of selected papers that were generated by that meeting.

Simulation Modelling, together with System Dynamics and intensive use of modern digital computer, which mean massive application, today very inexpensive and in the same time very powerful personal computer (PC-a), is one of the most suitable and effective scientific way for investigation of the dynamics behaviour of non-linear and complex: natural, technical and organization systems. The aim of this paper is to show the efficiency of the application of the System Dynamics Simulation Modelling in investigation of behaviors dynamics, one of the Port-Transhipment systems be presented with mental-verbal, structural and mathematical- computing modules, and will simulate transshipment port working processes.

Purpose-The purpose of this paper is to analyse some dynamic consequences of the theoretical foundations of the balanced scorecard (BSC) with the aid of a simulation approach based on part of a real BSC. Design/methodology/approach-The model includes five perspectives and a number of financial and non-financial measures. All indicators are defined and related to a number of assumed cause-and-effect relationships. Time lags are included to stipulate one of the most important characteristic of BSC. We use the model to simulate different strategies or scenarios over time. Through three different scenarios we also demonstrate the effects of different variables on the profit or RoCE (Return on Capital Employed). Findings-The results show that minimal changes in the three variables: skills, customer base and work in process may influence profit in different directions. Research limitations/implications-Our analytical model is based on assumed associations hypothesized from literature as well as from our study of a case. In this type of model, the sensitivity of our results with respect to the assumptions should be analysed in subsequent studies. In addition, our model should be extended to cover a complete BSC of an actual company. Practical implications-The model may be used as the first step in putting numbers on an integrated BSC model. The model is our first attempt to study an analytical version of BSC and to make inferences concerning optimal or rational relationships between different indicators and perspectives. The credibility or benefit of the model is insight into the finality of a model but it can also be used as a teaching exercise of BSC. It is easy to extend our model to more realistic circumstances, by including more measures or change time lags. Using the assumed cause-and-effect relationships between financial and non-financial performance measures, attention should also be paid to the definitions and the number of indicators. Originality/value-A large number of case studies and surveys are now present in BSC literature. However, there is a lack of more theoretical and analytical modelling of the BSC. Our paper just throws a little light on this modelling approach.

This paper explores the nature of communication and information flows in critical medical environments to inform the design of public website support. Results are presented of a study of communication in Intensive Care Units (ICU), where data was collected from the website owners, public users of the site and ICU clinicians who traditionally find communication with families of patients difficult. The paper presents the results of this research aimed at understanding the situation and needs of potential website users. The study has provided a greater understanding of how information technologies can help to resolve problems that arise with the ad-hoc, face-to-face communication that currently occurs in this area. To underpin the research a systems-dynamics model of information flows in an ICU, was developed in an evolutionary fashion using Stella software. The modelling process was informed by a review of literature, as well as data from various stakeholder groups. The model provided a means of re-interpreting the data, encapsulating the knowledge gained from the study and visualising the research findings in an innovative way that is enabling the project to move forward.

Indonesian teak forest plantation contributes to more than 35% of world teak forests. Perhutani, a state owned company, manages one million Ha of teak plantation area, while local communities manages teak agro-forests outside the state forest that amounts to 160,000 Ha. Javanese teak provides employments and livelihoods to millions of people. However, teak related income distribution is rarely known as well as future scenarios to make it fairer and sustainable viable to teak growers. This paper describes the use of systems dynamics to mimic value chain of teak from the forest to the final furniture market using phases of conceptual design, model specification, model evaluation and model uses. The model comprises Perhutani plantation teak, community agro-forest, teak log trading, furniture manufacturing and market. From the trends we observe Indonesian furniture role in world market is shrinking. The power asymmetry makes the furniture small-medium enterprises (SMEs) and teak growers get a small share of value added. Scenarios of boosting teak planting, fair trade and upgrading SMEs through vertical integration with lead firms can improve the sustainability of teak furniture business and enhance incomes of the poorest actors within the teak value chain.

Requirements Engineering techniques need to focus not only on the target technical system, as has traditionally been the case, but also on the interplay between business and system functionality. Whether a business wishes to exploit advances in technology to achieve new strategic objectives or to organise work in innovative ways, the process of Requirements Engineering could and should present opportunities for modelling and evaluating the potential impact that technology can bring about to the enterprise. This chapter discusses a co-designing process that offers opportunities of change to both the business and its underlying technical systems, in a synergistic manner. In these design situations some of the most challenging projects involve multiple stakeholders from different participating organisations, subcontractors, divisions etc who may have a diversity of expertise, come from different organisational cultures and often have competing goals. Stakeholders are faced with many different alternative future 'worlds' each one demanding a possibly different development strategy. There are acute questions about the potential structure of the new business system and how key variables in this structure could impact on the dynamics of the system. This chapter presents a framework which enables the evaluation of requirements through (a) system dynamics modelling, (b) ontology modelling, (c) scenario modelling and (d) rationale modelling. System dynamics modelling is used to define the behaviour of an enterprise system in terms of four perspectives. Ontology modelling is used to formally define invariant components of the physical and social world within the enterprise domain. Scenario modelling is used to identify critical variables and by quantitatively analyzing the effects of these variables through simulation to better understand the dynamic behaviour of the possible future structures. Rationale modelling is used to assist collaborative discussions when considering either ontology models or scenarios for change, developing maps, which chart the assumptions and reasoning behind key decisions during the requirements process.

Having effective modeling tools at the disposal of catchment managers and planners are essential to developing more effective future water management strategies. The actual projections of the demand and supply are often very dependent and interrelated with many variables, including each other for most catchments. The traditional approach used by water managers, whereby the demand based on population increase trend and water availability (supply) forecasts are calculated separately, is limited in its use due to this restriction. This is most noticed through the lack of consideration of the dynamic interrelationships that can occur between the supply and demand sides of water. This is where System Dynamic modelling can be used as a novel technique that can consider all the interdependencies to help accurately assess a catchment's future water availability and use. This report looked at creating a generic model of a catchment with competing demands and supply considerations that al...

Sustainability is a commitment to a new way of commissioning business activities that addresses balanced prosperity of social, economic and environmental dimensions of businesses. A sustainable business model is a roadmap for achieving sustainability and deals with the issues and dynamic relationships of sustainable dimensions of the businesses. A decision-making system that purports to support this sustainability commitment should facilitate development of sustainable business strategies, and translation of existing business operations into sustainable business processes. The system should also enable us capturing and managing sustainability related data for supporting the strategy development processes, business process reengineering processes and sustainability reporting processes. To achieve this goal we need a sustainable modelling and reporting framework that encapsulates different modelling processes e.g. decision support modelling, systems dynamics modelling, scenario modelling, simulation modelling, business process modelling, data modelling, and information modelling within a single framework. However, currently available sustainability modelling and reporting frameworks are neither integrated nor exhaustively backed by tools and technologies to support the sustainable business requirements; they also do not support the complete life cycle of a business transformation process. Therefore, businesses are facing increasing difficulty to develop, integrate and apply sustainable strategies and operations into their core business systems. This paper proposes a generic domain independent sustainability modelling and reporting framework that integrates various modelling processes for developing sustainable business models and sustainability reports. The framework encapsulates the sustainability models, modelling and reporting processes and aligns with the sustainable business framework.

Reference modes are the patterns of dynamic behaviour produced by feedback structures linking variables considered key to a specific problem. Identifying reference modes can be a challenge when data is scanty or available from a variety of sources and presented at different levels of aggregation. Lack of unequivocal reference modes can lead to ambiguity and conflict among stakeholders. This paper describes an attempt to identify and specify reference modes for the problem of dryland salinity. The method suggested by Saeed (2002) was applied. Dryland salinity in the Murray Darling Basin of Australia is used as a case study. The extent of the salinity problem in the Murray Darling Basin is described. Sources and availability of data for key salinity parameters are then evaluated. Insights gained from application of Saeed's method are discussed. Shortcomings of the method can be reduced through extensive and close involvement of stakeholders right from earliest stages when attempt...

Small ruminants are important assets in several regions of the world. They account for more than half of the domesticated ruminants. Despite the growth in goat production in the world (more than 2% per ye. ar), research related to goat production is less than desired. One underused but potentially valuable approach for research on small ruminants is sim ulation modelling. Models of the components of small ruminant systems can enhance the financial returns and reduce negative environmental impacts. These models can be used to assess many dimensions of small ruminant production, from rumen dynamics to economic policies designed to support small ruminant production. Understanding the nutrition, pro duction, and economic policy feedback signals and planning ahead is crucial to build a robust and integrated production activity that can be managed under different production scenarios. System Dynamics (SD) is a computer-aided modelling methodology that can be used to perform policy analysis and decision support system (DSS) applied to dynamic problems arising in complex social, managerial, economic. or ecological dynamic systems characterized by interdependence, mutual interaction, information feedback. and circular causality. SD can be used as a modelling tool to aggregate knowledge to solve d ifferent types of problems that have a limited scope to a specific location or have broad trends of applications across locations and areas of science. Important issues of broad application include the bearings ofanimal production in the climate change and the impacts of climate change in animal production, alternative production scenarios ofanimal and crop integra tion, associations between animal production and business (economics, marketing). The trend of increasing small ruminants in tropical and subtropical regions and an increasing pressure on tropical and subtropical livestock systems to produce food, to feed livestock. and to produce energy crops warrants the development ofDSS to address issues such as what is the "real" benefits of livestock. the negative impacts livestock can have on greenhouse-gas emissions and the environment, and the effects ofclimate change on livestock systems.

Javanese teak forest constitutes more than 35% of world teak forests. It provides employment and livelihood to millions of people. This paper describes the use of systems dynamics to mimic the value chain of teak from forest to final furniture market using phases of conceptual design, model specification, model evaluation and model uses. The model comprises Perhutani plantation teak, community agroforest, teak log trading, furniture manufacturing and market. From the model we observe baseline trends of teak forest and incomes to various actors participating in teak business including forest state enterprise Perhutani, local communities, brokers, manufacturers and retailers. We use the model to produce governance scenarios of fair trade and vertical integration, their impacts on actors' income and the sustainability of teak plantations.

While large-scale literature reviews are nowadays becoming a staple element of modern research practice, there are many challenges in taking on such an endeavour, yet little evidence of previous studies addressing these challenges exists. This paper introduces a practical and efficient review framework for extremely large corpora of literature, refined by five parallel implementations within a multi-disciplinary project aiming to map out the research and practice landscape of Modelling, Simulation, and Management methods, spanning a variety of sectors of application where such methods have made a significant impact. Centred on searching and screening techniques along with the use of some emerging IT-assisted analytic and visualisation tools, the proposed framework consists of four key methodological elements to deal with the scale of the reviews, namely: a) an incremental and iterative review structure, b) a 3-stage screening phase including filtering, sampling and sifting, c) use of visualisation tools, and d) reference chasing (both forward and backward). Five parallel implementations of systematically conducted literature search and screening yielded a total initial search result of 146 087 papers., ultimately narrowed down to a final set of 1383 papers which was manageable within the limited time and other constraints of this research work.

System dynamics software STELLA is used to obtain mass and thermal balances of a spring in the Orakeikorako geothermal field, New Zealand, based on field measurements of water level, barometric pressure, rainfall and spring temperature. The model identifies the interactions of the principal influences on spring behaviour of rainfall, groundwater, geothermal steam and barometric pressure. The geothermal steam inflow estimated from the model, of about 0.022 kg/s, confirms the existence of a weak hydraulic connection with a deeper geothermal reservoir.

A custom-designed combination of a chat tool and a wiki tool was used to engage postgraduate education students online in system dynamics modelling tasks. The purpose of the course was to familiarise students with core concepts of the complexity sciences, and to introduce them to modelling complex systems as a means to research processes of learning and organisational change. The rationale for the online course as well as the technology employed is described. Observations from two student teams using the Stella™ modelling software while cooperating in the online learning environment are reported, both with respect to their modelling activities as well as their team coordination behavior. We conclude with an identification of the main advantages of learning about a difficult subject area collaboratively and net-based.

Biosorption of heavy metals using membrane reactors as confining devise for free cells is an alternative process to remove these metallic pollutants from aqueous solution. In this paper, experimental data and modelling of heavy metal biosorption onto Sphaerotilus natans cells confined by a ultrafiltration/microfiltration (UF/MF) membrane reactor are reported. Biosorption tests using single and binary metallic solutions (Cu, Pb and Cu-Pb) denoted the biomass affinity (PbNCu), the competition among metals simultaneously present in the system, the filtrate flux decline and the change of metal retention coefficient on the membrane for pore plugging by cell fragments. Dynamic modelling is developed considering the unsteady mass balances of the metal in the system and the equilibrium parameters obtained by biosorption batch tests using Langmuir models. Experimental validation of the dynamic models denoted the importance of partial degradation of cells, which is specifically considered in modelling by introducing a time-depending profile for the biomass concentration. D