Selection of simulation tools for improving supply chain performance

Simulation is an effective method for improving supply chain performance. However, there is limited advice available to assist practitioners in selecting the most appropriate method for a given problem. Much of the advice that does exist relies on custom and practice rather than a rigorous conceptual or empirical analysis. An analysis of the different modelling techniques applied in the supply chain domain was conducted, and the three main approaches to simulation used were identified; these are System Dynamics (SD), Discrete Event Simulation (DES) and Agent Based Modelling (ABM). This research has examined these approaches in two stages. Firstly, a first principles analysis was carried out in order to challenge the received wisdom about their strengths and weaknesses and a series of propositions were developed from this initial analysis. The second stage was to use the case study approach to test these propositions and to provide further empirical evidence to support their comparison. The contributions of this research are both in terms of knowledge and practice. In terms of knowledge, this research is the first holistic cross paradigm comparison of the three main approaches in the supply chain domain. Case studies have involved building ‘back to back’ models of the same supply chain problem using SD and a discrete approach (either DES or ABM). This has led to contributions concerning the limitations of applying SD to operational problem types. SD has also been found to have risks when applied to strategic and policy problems. Discrete methods have been found to have potential for exploring strategic problem types. It has been found that discrete simulation methods can model material and information feedback successfully. Further insights have been gained into the relationship between modelling purpose and modelling approach. In terms of practice, the findings have been summarised in the form of a framework linking modelling purpose, problem characteristics and simulation approach.

Simulation in the supply chain context:matching the simulation tool to the problem

The supply chain can be a source of competitive advantage for the firm. Simulation is an effective tool for investigating supply chain problems. The three main simulation approaches in the supply chain context are System Dynamics (SD), Discrete Event Simulation (DES) and Agent Based Modelling (ABM). A sample from the literature suggests that whilst SD and ABM have been used to address strategic and planning problems, DES has mainly been used on planning and operational problems., A review of received wisdom suggests that historically, driven by custom and practice, certain simulation techniques have been focused on certain problem types. A theoretical review of the techniques, however, suggests that the scope of their application should be much wider and that supply chain practitioners could benefit from applying them in this broader way.

Disseminating a warning message to evacuate:a simulation study of the behaviour of neighbours

Large-scale evacuations are a recurring theme on news channels, whether in response to major natural or manmade disasters. The role of warning dissemination is a key part in the success of such large-scale evacuations and its inadequacy in certain cases has been a 'primary contribution to deaths and injuries' (Hayden et al.; 2007). Along with technology-driven 'official warning channels' (e.g. sirens, mass media), the role of unofficial channel (e.g. neighbours, personal contacts, volunteer wardens) has proven to be significant in warning the public of the need to evacuate. Although post-evacuation studies identify the behaviours of evacuees as disseminators of the warning message, there has not been a detailed study that quantifies the effects of such behaviour on the warning message dissemination. This paper develops an Agent-Based Simulation (ABS) model of multiple agents (evacuee households) in a hypothetical community to investigate the impact of behaviour as an unofficial channel on the overall warning dissemination. Parameters studied include the percentage of people who warn their neighbours, the efficiency of different official warning channels, and delay time to warn neighbours. Even with a low proportion of people willing to warn their neighbour, the results showed considerable impact on the overall warning dissemination. © 2012 Elsevier B.V. All rights reserved.

Informal dissemination scenarios and the effectiveness of evacuation warning dissemination of households:a simulation study

Timely warning of the public during large scale emergencies is essential to ensure safety and save lives. This ongoing study proposes an agent-based simulation model to simulate the warning message dissemination among the public considering both official channels and unofficial channels The proposed model was developed in NetLogo software for a hypothetical area, and requires input parameters such as effectiveness of each official source (%), estimated time to begin informing others, estimated time to inform others and estimated percentage of people (who do not relay the message). This paper demonstrates a means of factoring the behaviour of the public as informants into estimating the effectiveness of warningdissemination during large scale emergencies. The model provides a tool for the practitioner to test the potential impact of the informal channels on the overall warning time and sensitivity of the modelling parameters. The tool would help the practitioners to persuade evacuees to disseminate the warning message informing others similar to the ’Run to thy neighbour campaign conducted by the Red cross.

In-Motes Bins:a real time application for environmental monitoring in wireless sensor networks

In-Motes Bins is an agent based real time In-Motes application developed for sensing light and temperature variations in an environment. In-Motes is a mobile agent middleware that facilitates the rapid deployment of adaptive applications in Wireless Sensor Networks (WSN's). In-Motes Bins is based on the injection of mobile agents into the WSN that can migrate or clone following specific rules and performing application specific tasks. Using In-Motes we were able to create and rapidly deploy our application on a WSN consisting of 10 MICA2 motes. Our application was tested in a wine store for a period of four months. In this paper we present the In-Motes Bins application and provide a detailed evaluation of its implementation. © 2007 IEEE.

The impact of coordination on the effectiveness of last mile relief distribution

Last mile relief distribution is the final stage of humanitarian logistics. It refers to the supply of relief items from local distribution centers to the disaster affected people (Balcik et al., 2008). In the last mile relief distribution literature, researchers have focused on the use of optimisation techniques for determining the exact optimal solution (Liberatore et al., 2014), but there is a need to include behavioural factors with those optimisation techniques in order to obtain better predictive results. This paper will explain how improving the coordination factor increases the effectiveness of the last mile relief distribution process. There are two stages of methodology used to achieve the goal: Interviews: The authors conducted interviews with the Indian Government and with South Asian NGOs to identify the critical factors for final relief distribution. After thematic and content analysis of the interviews and the reports, the authors found some behavioural factors which affect the final relief distribution. Model building: Last mile relief distribution in India follows a specific framework described in the Indian Government disaster management handbook. We modelled this framework using agent based simulation and investigated the impact of coordination on effectiveness. We define effectiveness as the speed and accuracy with which aid is delivered to affected people. We tested through simulation modelling whether coordination improves effectiveness.

The challenges of representing human behaviour in simulation models:some case examples from supply chain, evacuation modelling and rail disruption

As more of the economy moves from traditional manufacturing to the service sector, the nature of work is becoming less tangible and thus, the representation of human behaviour in models is becoming more important. Representing human behaviour and decision making in models is challenging, both in terms of capturing the essence of the processes, and also the way that those behaviours and decisions are or can be represented in the models themselves. In order to advance understanding in this area, a useful first step is to evaluate and start to classify the various types of behaviour and decision making that are required to be modelled. This talk will attempt to set out and provide an initial classification of the different types of behaviour and decision making that a modeller might want to represent in a model. Then, it will be useful to start to assess the main methods of simulation in terms of their capability in representing these various aspects. The three main simulation methods, System Dynamics, Agent Based Modelling and Discrete Event Simulation all achieve this to varying degrees. There is some evidence that all three methods can, within limits, represent the key aspects of the system being modelled. The three simulation approaches are then assessed for their suitability in modelling these various aspects. Illustration of behavioural modelling will be provided from cases in supply chain management, evacuation modelling and rail disruption.

Advances in decision support systems on the endeavour for supply chain optimality

Industry practitioners are seeking to create optimal logistics networks through more efficient decision-making leading to a shift of power from a centralized position to a more decentralized approach. This has led to researchers, exploring with vigor, the application of agent based modeling (ABM) in supply chains and more recently, its impact on decision-making. This paper investigates reasons for the shift to decentralized decision-making and the impact on supply chains. Effective decentralization of decision-making with ABM and hybrid modeling is investigated, observing the methods and potential of achieving optimality.

Adómorál és adócsalás - társadalmi preferenciák és korlátozott racionalitás = Tax morale and tax system: social preferences and bounded rationality

Az adócsalásnak egy olyan modellcsaládját vizsgáljuk, ahol az egykulcsos adó kizárólag a közjavakat finanszírozza. Két megközelítés összehasonlítására összpontosítunk. Az elsőben minden dolgozó jövedelme azonos, és ebből minden évben annyit vall be, amennyi maximalizálja a nála maradó jövedelemből fedezhető fogyasztás nyújtotta hasznosság és a jövedelembevallásból fakadó hasznosság összegét. A második hasznosság három tényező szorzata: a dolgozó exogén adómorálja, a környezetében előző évben megfigyelt átlagos jövedelembevallás és saját bevallásából fakadó endogén hasznossága. A második megközelítésben az ágensek egyszerű heurisztikus szabályok szerint cselekszenek. Míg az optimalizáló modellben hagyományos Laffer-görbékkel találkozunk, addig a heurisztikán alapuló modellekben (lineárisan) növekvő Laffer-görbék jönnek létre. E különbség oka, hogy a heurisztikán alapuló modellben egy sajátos viselkedésfajta jelentkezik: számos ágens ingatag helyzetbe kerül, amelyben altruizmus és önzés között ingadozik. ________ The authors study a family of models of tax evasion, where a flat-rate tax only finances the provision of public goods and audits and wage differences are ne-glected. The paper focuses on comparing two modelling approaches. The first is based on optimizing agents, endowed with social preferences, their utility being the sum of private consumption and moral utility. The second approach involves agents acting according to simple heuristics. While the traditionally shaped Laffer curves are encountered in the optimizing model, the heuristics models exhibit (linearly) increasing Laffer curves. This difference is related to a peculiar type of behaviour: within the agent-based approach lurk a number of agents in a moral state of limbo, alternating between altruism and selfishness.

Megtakarítási típusok - egy adaptív-evolúciós megközelítés = Types of saving - an adaptive-evolutionary approach

A közgazdaságtanban az ágensalapú modellezés egyik alkalmazási területe a makro ökonómia. Ebben a tanulmányban néhány népszerű megtakarítási szabály létét feltételezve adaptív-evolúciós megközelítésben endogén módon próbálunk következtetni e szabályok relatív életképességére. Három különböző típusú ágenst vezetünk be: egy prudens, egy rövidlátó és egy, a permanensjövedelem-elméletnek megfelelően működőt. Rendkívül erős szelekciós nyomás mellett a prudens típus egyértelműen kiszorítja a másik kettőt. A második legéletképesebbnek a rövidlátó típus tűnik, de már közepes szelekciós nyomásnál sem tűnik el egyik típus sem. Szokásos tőkehatékonyság mellett a prudens típus túlzott beruházási tendenciát visz a gazdaságba, és a gazdaság az aranykori megtakarítási rátánál magasabbat ér el. A hitelkorlátok oldása még nagyobb mértékű túlzott beruházáshoz vezethet, a hitelek mennyiségének növekedése mellett a tőketulajdonosok mintegy "kizsákmányoltatják" magukat azokkal, akiknek nincs tőkejövedelmük. A hosszú távú átlagos fogyasztás szempontjából a három típus kiegyensúlyozott aránya adja a legjobb eredményt, ugyanakkor ez jóval nagyobb ingadozással jár, mint amikor csak prudens típusú háztartások léteznek. ____ Agent-based modelling techniques have been employed for some time in macroeconomics. This paper tests some popular saving rules in an adaptive-evolutionary context of looking at their relative survival values. The three types are prudent, short-sighted, and responsive to the permanent-income hypothesis. It is found that where selection pressure is very high, only the prudent type persists. The second most resilient seems to be the short-sighted type, but all three coexist even at medium levels of selection pressure. When the efficiency of capital approaches the level usually assumed in macroeconomics, the prudent type drives the economy towards excessive accumulation of capital, i. e. a long-term savings rate that exceeds the golden rule. If credit constraints are relaxed, this tendency strengthens as credit grows and capital-owners seem to allow themselves to be exploited" by workers. From the angle of average consumption, the best outcome is obtained from a random distribution of types, although this is accompanied by higher volatility.

Collaborative mediation

A Mediation System utilizes a central security mediator that is primarily concerned with securing the internal structure of the Mediation System. The current problem is that clients are unable to have authority and administrative rights over the security of their data during a transaction. In addition, this Mediation System is unsuited in presenting a metric that measures the level of confidence of security access rights. This creates a black-box perspective from the client towards the Mediation System and also gives no assurance to these clients that they have assigned the proper security access rights that reflect the current environment of the mediation system. This dissertation presents a Collaborative Information System (CIS) that uses an agent based approach to encapsulate collaborative information and security policies within the Mediation System which are under the control of the clients of the Mediation System. In conjunction with the CIS's Stochastic Security Framework it is possible to take a probabilistic approach in modeling the security access rights of a collaboration transaction. The research results showed that it is feasible to construct a Mediation System utilizing agents and stochastic equations to establish an environment where the client has authority and administrative control in assigning security access rights to their collaborative data that can establish a metric that measures the level of confidence of these assigned rights.

Frameworks for Systemic and Structural Analysis of Financial Innovations in Infrastructure

Financial innovations have emerged globally to close the gap between the rising global demand for infrastructures and the availability of financing sources offered by traditional financing mechanisms such as fuel taxation, tax-exempt bonds, and federal and state funds. The key to sustainable innovative financing mechanisms is effective policymaking. This paper discusses the theoretical framework of a research study whose objective is to structurally and systemically assess financial innovations in global infrastructures. The research aims to create analysis frameworks, taxonomies and constructs, and simulation models pertaining to the dynamics of the innovation process to be used in policy analysis. Structural assessment of innovative financing focuses on the typologies and loci of innovations and evaluates the performance of different types of innovative financing mechanisms. Systemic analysis of innovative financing explores the determinants of the innovation process using the System of Innovation approach. The final deliverables of the research include propositions pertaining to the constituents of System of Innovation for infrastructure finance which include the players, institutions, activities, and networks. These static constructs are used to develop a hybrid Agent-Based/System Dynamics simulation model to derive propositions regarding the emergent dynamics of the system. The initial outcomes of the research study are presented in this paper and include: (a) an archetype for mapping innovative financing mechanisms, (b) a System of Systems-based analysis framework to identify the dimensions of Systems of Innovation analyses, and (c) initial observations regarding the players, institutions, activities, and networks of the System of Innovation in the context of the U.S. transportation infrastructure financing.

Avaliação de floculante natural à base de Moringa oleifera no tratamento de água produzida na indústria do petróleo: aplicação da técnica combinada floculação/flotação

The principal effluent in the oil industry is the produced water, which is commonly associated to the produced oil. It presents a pronounced volume of production and it can be reflected on the environment and society, if its discharge is unappropriated. Therefore, it is indispensable a valuable careful to establish and maintain its management. The traditional treatment of produced water, usualy includes both tecniques, flocculation and flotation. At flocculation processes, there are traditional floculant agents that aren’t well specified by tecnichal information tables and still expensive. As for the flotation process, it’s the step in which is possible to separate the suspended particles in the effluent. The dissolved air flotation (DAF) is a technique that has been consolidating economically and environmentally, presenting great reliability when compared with other processes. The DAF is presented as a process widely used in various fields of water and wastewater treatment around the globe. In this regard, this study was aimed to evaluate the potential of an alternative natural flocculant agent based on Moringa oleifera to reduce the amount of oil and grease (TOG) in produced water from the oil industry by the method of flocculation/DAF. the natural flocculant agent was evaluated by its efficacy, as well as its efficiency when compared with two commercial flocculant agents normally used by the petroleum industry. The experiments were conducted following an experimental design and the overall efficiencies for all flocculants were treated through statistical calculation based on the use of STATISTICA software version 10.0. Therefore, contour surfaces were obtained from the experimental design and were interpreted in terms of the response variable removal efficiency TOG (total oil and greases). The plan still allowed to obtain mathematical models for calculating the response variable in the studied conditions. Commercial flocculants showed similar behavior, with an average overall efficiency of 90% for oil removal, however it is the economical analysis the decisive factor to choose one of these flocculant agents to the process. The natural alternative flocculant agent based on Moringa oleifera showed lower separation efficiency than those of commercials one (average 70%), on the other hand this flocculant causes less environmental impacts and it´s less expensive

Investigating the Tradespace between Increased Automation and Optimal Manning on Aircraft Carrier Decks

With increasing prevalence and capabilities of autonomous systems as part of complex heterogeneous manned-unmanned environments (HMUEs), an important consideration is the impact of the introduction of automation on the optimal assignment of human personnel. The US Navy has implemented optimal staffing techniques before in the 1990's and 2000's with a "minimal staffing" approach. The results were poor, leading to the degradation of Naval preparedness. Clearly, another approach to determining optimal staffing is necessary. To this end, the goal of this research is to develop human performance models for use in determining optimal manning of HMUEs. The human performance models are developed using an agent-based simulation of the aircraft carrier flight deck, a representative safety-critical HMUE. The Personnel Multi-Agent Safety and Control Simulation (PMASCS) simulates and analyzes the effects of introducing generalized maintenance crew skill sets and accelerated failure repair times on the overall performance and safety of the carrier flight deck. A behavioral model of four operator types (ordnance officers, chocks and chains, fueling officers, plane captains, and maintenance operators) is presented here along with an aircraft failure model. The main focus of this work is on the maintenance operators and aircraft failure modeling, since they have a direct impact on total launch time, a primary metric for carrier deck performance. With PMASCS I explore the effects of two variables on total launch time of 22 aircraft: 1) skill level of maintenance operators and 2) aircraft failure repair times while on the catapult (referred to as Phase 4 repair times). It is found that neither introducing a generic skill set to maintenance crews nor introducing a technology to accelerate Phase 4 aircraft repair times improves the average total launch time of 22 aircraft. An optimal manning level of 3 maintenance crews is found under all conditions, the point at which any additional maintenance crews does not reduce the total launch time. An additional discussion is included about how these results change if the operations are relieved of the bottleneck of installing the holdback bar at launch time.

D4.3 Prototype Software (Documentation)

The agent-based social simulation component of the TELL ME project (WP4) developed prototype software to assist communications planners to understand the complex relationships between communication, personal protective behaviour and epidemic spread. Using the simulation, planners can enter different potential communications plans, and see their simulated effect on attitudes, behaviour and the consequent effect on an influenza epidemic.

The model and the software to run the model are both freely available (see section 2.2.1 for instructions on how to obtain the relevant files). This report provides the documentation for the prototype software. The major component is the user guide (Section 2). This provides instructions on how to set up the software, some training scenarios to become familiar with the model operation and use, and details about the model controls and output.

The model contains many parameters. Default values and their source are described at Section 3. These are unlikely to be suitable for all countries, and may also need to be changed as new research is conducted. Instructions for how to customise these values are also included (see section 3.5).

The final technical reference contains two parts. The first is a guide for advanced users who wish to run multiple simulations and analyse the results (section 4.1). The second is to orient programmers who wish to adapt or extend the simulation model (section 4.2). This material is not suitable for general users.