Modelling Fresh Strawberry Supply "From-Farm-to-Fork" as a Complex Adaptive Network

 The purpose of this study is to model and thereby enable simulation of the complete business entity of fresh food supply. A case narrative of fresh strawberry supply provides basis for this modelling. Lamming et al. (2000) point to the importance of discerning industry-specific product features (or particularities) regarding managing supply networks when discussing elements in "an initial classification of a supply network" while Fisher (1997) and Christopher et al. (2006, 2009) point to the lack of adopting SCM models to variations in products and market types as an important source of SCM failure. In this study we have chosen to move along a research path towards developing an adapted approach to model end-to-end fresh food supply influenced by a combination of SCM, system dynamics and complex adaptive network thinking...

Агентно-орієнтовані моделі обчислювальної економіки: особливості, переваги і недоліки

Розглядаються основні підходи до розробки агентно-орієнтованих моделей обчислювальної економіки. Визначаються характерні риси агентно-орієнтованих моделей (АОМ). Наводяться основні цілі створення агентно-орієнтованих моделей. Пояснюються деякі способи класифікації АОМ та виділяються базові типи АОМ. Обговорені основні переваги та недоліки АОМ. Наведено короткий огляд моделі EURACE.Рассматриваются основные подходы к разработке агентно-ориентированных моделей вычислительной экономики. Определяются характерные черты агентно-ориентированных моделей (АОМ). Приводятся основные цели создания агентно-ориентированных моделей. Поясняются некоторые способы классификации АОМ и выделяются базовые типы АОМ. Обсуждены основные преимущества и недостатки АОМ. Приведен краткий обзор модели EURACE.The main approaches to agent-based models design are discussed. The characteristic features of agent-based models (ABM) are defined. The main purposes of ABM) construction are given. Some possible classifications are explained. Basic types of ABM are indicated. The main advantages and disadvantages of ABM use are noted. The brief review of the EURACE model is presented

Structural, efficiency and income effects of direct payments: an analysis of different payment schemes for the German region 'Hohenlohe'

The objective of this paper is to work out some fundamental dynamic effects on agricultural structure, farm incomes, and efficiency that result from decoupled income payments, the transfer of payments together with a progressive payment cut. To do so, we apply the agent-based model AgriPoliS (Agri-cultural Policy Simulator). AgriPoliS is a normative spatial and dynamic model of regional agricul-tural structures that takes account of actions and interactions between a large number of individually acting farms. The model is calibrated to the region 'Hohenlohe' in Baden-Württemberg which is char-acterised by intensive livestock farming on the plains and extensive cattle and dairy farming in more remote valleys. The policy simulations show that impacts on structural change, competitiveness, and income distribution vary greatly depending on how the policy scheme is implemented. If direct pay-ments are completely decoupled from land use (no obligation to farm land) this has significant and lasting effects on the competitiveness of agriculture, structural change, farmers’ incomes and land-use.agricultural policy analysis, agent-based models, decoupling

A Mathematical Framework for Agent Based Models of Complex Biological Networks

Agent-based modeling and simulation is a useful method to study biological phenomena in a wide range of fields, from molecular biology to ecology. Since there is currently no agreed-upon standard way to specify such models it is not always easy to use published models. Also, since model descriptions are not usually given in mathematical terms, it is difficult to bring mathematical analysis tools to bear, so that models are typically studied through simulation. In order to address this issue, Grimm et al. proposed a protocol for model specification, the so-called ODD protocol, which provides a standard way to describe models. This paper proposes an addition to the ODD protocol which allows the description of an agent-based model as a dynamical system, which provides access to computational and theoretical tools for its analysis. The mathematical framework is that of algebraic models, that is, time-discrete dynamical systems with algebraic structure. It is shown by way of several examples how this mathematical specification can help with model analysis.Comment: To appear in Bulletin of Mathematical Biolog

A Framework for Megascale Agent Based Model Simulations on Graphics Processing Units

Agent-based modeling is a technique for modeling dynamic systems from the bottom up. Individual elements of the system are represented computationally as agents. The system-level behaviors emerge from the micro-level interactions of the agents. Contemporary state-of-the-art agent-based modeling toolkits are essentially discrete-event simulators designed to execute serially on the Central Processing Unit (CPU). They simulate Agent-Based Models (ABMs) by executing agent actions one at a time. In addition to imposing an un-natural execution order, these toolkits have limited scalability. In this article, we investigate data-parallel computer architectures such as Graphics Processing Units (GPUs) to simulate large scale ABMs. We have developed a series of efficient, data parallel algorithms for handling environment updates, various agent interactions, agent death and replication, and gathering statistics. We present three fundamental innovations that provide unprecedented scalability. The first is a novel stochastic memory allocator which enables parallel agent replication in O(1) average time. The second is a technique for resolving precedence constraints for agent actions in parallel. The third is a method that uses specialized graphics hardware, to gather and process statistical measures. These techniques have been implemented on a modern day GPU resulting in a substantial performance increase. We believe that our system is the first ever completely GPU based agent simulation framework. Although GPUs are the focus of our current implementations, our techniques can easily be adapted to other data-parallel architectures. We have benchmarked our framework against contemporary toolkits using two popular ABMs, namely, SugarScape and StupidModel.GPGPU, Agent Based Modeling, Data Parallel Algorithms, Stochastic Simulations

Agent-Based Modeling in Social Science, History, and Philosophy: An Introduction

Agent-based modeling has become a common and well-established tool in the social sciences and certain of the humanities. Here, we aim to provide an overview of the different modeling approaches in current use. Our discussion unfolds in two parts: we first classify different aspects of the model-building process and identify a number of characteristics shared by most agent-based models in the humanities and social sciences; then we map relevant differences between the various modeling approaches. We classify these into different dimensions including the type of target systems addressed, the intended modeling goals, and the models’ degree of abstraction. Along the way, we provide reference to related debates in contemporary philosophy of science

Agent-Based Modeling in Social Science, History, and Philosophy: An Introduction

Agent-based modeling has become a common and well-established tool in the social sciences and certain of the humanities. Here, we aim to provide an overview of the different modeling approaches in current use. Our discussion unfolds in two parts: we first classify different aspects of the model-building process and identify a number of characteristics shared by most agent-based models in the humanities and social sciences; then we map relevant differences between the various modeling approaches. We classify these into different dimensions including the type of target systems addressed, the intended modeling goals, and the models’ degree of abstraction. Along the way, we provide reference to related debates in contemporary philosophy of science

Agent-based modelling of offshore upstream petroleum logistics

Faced with dwindling oil prices, the petroleum industry now needs to economize its operations. A case study of upstream petroleum logistics, the management of supplies to and from petroleum platforms and rigs, is used to describe current logistics and supply chain management (SCM) challenges facing these operations in Norway. The provided case narrative reveals how an integrated planning system used to co-ordinate operations is proven relatively difficult to implement and use. As alternative research approach agent-based modelling (ABM) is applied and discussed in association with actor network theory in a SCM business-functional setting to theoretically ground use of ABM as methodology. An empirically-grounded conceptual model, the first stage of ABM methodology, is created for petroleum logistics. Findings from this first stage of inquiry also suggest how and why ABM is applicable in petroleum logistics and SCM. Keywords: actor network theory, agent-based modelling, petroleum logistics, supply chain management.publishedVersio