Software agents as a versatile simulation tool to model complex systems

Software agents as a versatile simulation tool to model complex system

Computational Intelligence for Modeling, Control, Optimization, Forecasting and Diagnostics in Photovoltaic Applications

This book is a Special Issue Reprint edited by Prof. Massimo Vitelli and Dr. Luigi Costanzo. It contains original research articles covering, but not limited to, the following topics: maximum power point tracking techniques; forecasting techniques; sizing and optimization of PV components and systems; PV modeling; reconfiguration algorithms; fault diagnosis; mismatching detection; decision processes for grid operators

A multi-agent system for simulating land-use and land-cover change in the Atankwidi catchment of Upper East Ghana

Land-use and land-cover change (LUCC), which is a general term for the human modification of the Earth’s terrestrial surface, increasingly gains attention in the scientific community, due to its vast global extent and the role it plays in the Earth system functioning. About one third to one half of the global land surface has been modified by humans, and these changes are highly interrelated with many environmental, economic and social processes and problems. However, studies on LUCC processes are often challenged by the complex nature and unexpected behavior of both human drivers and natural constraints. Many studies tend to focus either on the human or the environmental part of LUCC systems, thus neglecting the interrelationships and responses among these two components. Many aspects of complexity can be overcome by a multi-agent based approach, whose design allows an integrated representation of the feedbacks, hierarchies and interdependencies of the coupled human-environment system of LUCC. A multi-agent simulation model (GH-LUDAS - GHana Land Use DynAmic Simulator) was developed to model this coupled human-environment system in a small-scale catchment in Ghana, thereby providing a simulation tool to predict land-use/cover patterns as related to socio-economic indicators. Apart from pure prediction, the aim of the model is to explore alternative future pathways of LUCC under selected policy, demographic and climatic conditions in order to provide stakeholders with support for making better-informed decisions about land resource management. Multi-agent based modelling is an approach to design computational models for simulating the actions and interactions of autonomous individuals (i.e. agents) in a network, with a view to assessing their effects on the system as a whole. Thus, agent-based modeling can be regarded as a bottom-up modeling approach, as the behavior and interactions of single agents are specified, and complexity is considered to emerge from these specifications. Following this mindset, GH-LUDAS consists of four modules, which represent the main components of the human-evironment system of LUCC. The Human Module consists of collections of human agents (i.e. farm households), which are endowed with a set of attributes and autonomous behavior templates (i.e. the Decision Module), regulating land-use related decisions in response to the human agent’s attributes and those of its environment. The Landscape Module consists of collections of individual landscape agents (i.e. land patches of size 30 x 30 m), which are characterized by biophysical attributes and ecological mechanisms, which work in response to human decision-making and natural constraints (e.g. crop yield, land-cover change). The Global-policy Module consists of a range of external parameters, which allow the exploration of alternative future pathways of LUCC, and which relate to attributes of both human and landscape agents. The ability to provide an integrated representation of these components is one of the strengths of this approach, and its flexibility allows the upgrading and modification of processes where these have not yet been considered. The developed model was applied to a small-scale catchment in Upper East Ghana, the Atankwidi catchment, which covers an area of about 159 km2. Spatially explicit data were obtained from an ASTER image, digitalmaps, an extensive land cover inventory and intensive household surveys. Field data were used to specify attributes and calibrate behavioral submodels of households and land patches. Considered external factors were the policies of dam construction and credit access, demographic changes, and rainfall change. Simulation outputs consist of a spatially and temporally explicit land use/cover map, visual graphs, and export files of selected land-use and livelihood indicators. These convenient output visualization tools, together with the user-friendly interface of GH-LUDAS, allow stakeholders to simulate and analyze selected scenarios, which can serve as a basis for discussion and communication among stakeholders and policy-makers. Simulation results suggest that, among others, the policy of dam construction had much less effect on average annual income than that of credit provision, although it is the much more costly option in comparison to a credit scheme. Furthermore, a decline in annual rainfall seemed to trigger a shift towards cash cropping and non-farm activities, which could compensate for the losses in harvest caused by decreased precipitation. All simulated spatiotemporal data developed by these simulations can be used for further scientific analyses using GIS and statistical packages, thereby providing a basis for further understanding of local LUCC processes in Northern Ghana.Ein agenten-basiertes Modell zur Simulierung von Landnutzungs- und Landbedeckungsänderungen im Einzugsgebiet des Atankwidi in Nordost-Ghana Landnutzungs- und Landbedeckungsänderungen, die die durch den Menschen verursachte Modifizierung der Landoberfläche der Erde bezeichnen, erfahren zunehmende Aufmerksamkeit in der wissenschaftlichen Welt, aufgrund ihres weltweiten Ausmaßes und der Rolle, die sie für die Funktionsweise der Erde spielen. Zwischen einem Drittel und der Hälfte der Landoberfläche sind bereits durch menschliche Einflüsse verändert worden, wobei diese Änderungen wichtige Wechselbeziehungen mit ökologischen, ökonomischen und sozialen Prozessen und Problematiken aufweisen. Studien, die sich mit Landnutzungs- und Landbedeckungsänderungen befassen, repräsentieren die KomplexitätmenschlicherVerhaltensweisen und ökologischer Bedingungen oft nur in unzureichender Weise. Viele Studien tendieren dazu, nur eineKomponente des ökologischen Systems, das ausmenschlichen wie aus umweltbedingten Prozessen besteht, zu erfassen, und vernachlässigen dabei die Wechselbeziehungen zwischen diesen beiden Komponenten. Der agenten-basierte Modellierungsansatz hat die Fähigkeit, viele Eigenschaften von komplexen Systemen zu integrieren, und ermöglicht die Modellierung von Rückkopplungen, Wechselbeziehungen und skalen-abhängigen Prozessen des ökologischen Systems. In dieser Arbeit wurde ein agenten-basiertes Modell namens GH-LUDAS (Ghana - Land Use DynAmic Simulator) entwickelt, das Landnutzungs- und Landbedeckungsänderungen sowie zugehörige sozio-ökonomische Indikatoren in einem Flusseinzugsgebiet desWhite Volta in Nord-Ghana simuliert. Das Ziel desModells ist sowohl die Prognostizierung von Landbedeckungs-/Landnutzungsänderungen als auch die Evaluierung von möglichen Zukunftsverläufen unter gegebenen politischen Maßnahmen, demographischen Veränderungen sowieKlimawandel. Die Simulierung solcher Szenarien kann die Entscheidungsfindungen lokaler Akteure bezüglich Landnutzung unterstützen und als Ausgangspunkt für Diskussionen unter lokalen Entscheidungsträgern dienen. Der agenten-basierte Modellansatz kennzeichnet sich durch die Modellierung der Aktionen und der Interaktionen einzelner Individuen (i.e. Agenten), deren Spezifikationen in komplexe Phänomene auf Systemebene resultieren. Agenten-basierte Modellierung kann daher als ein ’bottom-up approach’ bezeichnet werden, da die Systembeziehungen nicht auf oberster Ebene spezifiziert werden, sondern von den Prozessen zwischen einzelnen Agenten reguliert werden. Dieser Philosophie folgend, gliedert sich GH-LUDAS in vier Hauptmodule. Das soziale Modul besteht aus einer Kollektion von menschlichen Agenten, die landwirtschaftliche Haushalte repräsentieren, und die mit einer Reihe von Attributen und Entscheidungsalgorithmen ausgestattet sind. Diese Algorithmen, die innerhalb des Entscheidungmoduls spezifiziert sind, regulieren Reaktionen auf persönliche wie auf umweltbedingte Attribute und Prozesse. Das Umweltmodul besteht aus landschaftlichen Agenten, die aus Pixeln von 30 m x 30 m bestehen, und die mit eigenen Attributen sowie ökologischen Mechanismen, die auf menschliche Entscheidungen sowie auf natürliche Prozesse reagieren (z.B. Ernteertrag, Landbedeckungsänderungen), ausgestattet sind. Das globaleModul besteht aus einer Reihe von externen Parametern, die von Modellnutzern reguliert werden können, und die Attribute von menschlichen und landschaftlichen Agenten direkt beeinflussen. Die Fähigkeit, diese Komponenten zu verbinden und miteinander zu integrieren, ist eine der Stärken des agenten-basierten Ansatzes, und seine Flexibilität erlaubt die Integrierung von Prozessen, wo diese (noch) nicht berücksichtigt worden sind. Das Modell wurde speziell für das Flusseinzugsgebiet des Atankwidi in Nordost- Ghana entwickelt, das eine Fläche von etwa 159 km2 aufweist. Räumlich explizite Daten wurden auf der Basis eines ASTER Satellitenbildes, digitalen Karten, einer weiträumigen Bestandsaufnahme von Landbedeckung, und fokussierten Haushaltsbefragungen generiert. Auf diesen Felddaten basierend, wurden die Attribute sowie die reaktiven Mechanismen menschlicher und landschaftlicher Agenten spezifiziert und kalibriert. Die externen Parameter des Modells umfassen Maßnahmen, die Dammbau und Kreditvergabe betreffen, sowie demographische Veränderungen und Reduzierung des jährlichen Niederschlags. Die Ausgabe der Modellsimulationen erfolgt durch eine zeitlich und räumlich explizite Visualisierung von lokaler Landbedeckung/Landnutzung, Graphiken, und exportierbaren Dateien einer Auswahl an Systemindikatoren. Diese Bandbreite von Ausgabemöglichkeiten, in Kombination mit einer benutzerfreundlichenModelloberfläche ermöglichen beteiligten Akteuren, ausgewählte Szenarien zu simulieren und zu analysieren, und kann zur Diskussion und Kommunikation zwischen Akteuren und Entscheidungsträgern beitragen. Die Resultate von bereits simulierten Szenarien deuten unter anderem darauf hin, das die Strategie des Dammbaus eine geringere Wirkung auf durchschnittliches Einkommen hat als dieMaßnahme der Kreditvergabe, obwohl ersteres die bei weitem kostspieligereMaßnahme darstellt. Desweiteren zeigt sich, dass eine Reduzierung des jährlichen Niederschlags eine Verlagerung auf marktfähigere Agrarprodukte (cash crops) und nichtlandwirtschaftliche Einkommensstrategien auszulösen scheint, die die Reduzierung des Ertrags, verursacht durch die geringere Niederschlagsmenge, kompensieren. Alle simulierten zeitlichen und räumlichen Daten können weiteren wissenschaftlichen Analysen in GIS- und Statistik-Programmen unterzogen werden, und zu einer Erweiterung des Verständnisses von lokalen Landnutzungsund Landbedeckungsänderungen in Nord-Ghana beitragen

Analysis of a 3-tier distributed architecture for the sector Anti Air Warfare Center.

The Marine Air Command and Control System (MACCS) is composed of a collection of legacy, stovepipe Automated Information Systems (AIS), each of which contain functionality which is widely duplicated throughout the MACCS. A proposed alternative architecture, the Common Air Command Control System (CAC2S) , would leverage the investment currently being made in Command, Control, Communications, Computing, and Intelligence (C4I) systems which provide a robust set of functional services common to a wide range of mission critical applications. A plan for migration from the MACCS architecture to the CAC2S architecture is a required component for a successful transition. This thesis describes the messaging and database methodology, the ongoing efforts to identify common data types and processes, and a proposed three tier distributed object architecture, which will guide the MACCS migration to the CAC2S. A software Engineering tool, the Naval Postgraduate School Computer Aided Prototyping System (CAPS), is used to model a component of the MACCS, the Sector Anti Air Warfare Center (SAAWC), in an effort to more precisely identify the critical data type representations and data processing requirements needed to properly specify the CAC2S. As a result of this effort, a blueprint has been created to describe the methodology and analysis required to effect the migration from the MACCS architecture to the CAC2S visionhttp://archive.org/details/analysisof3tierd00howeApproved for public release; distribution is unlimited

Energy Harvesting from a Vortex Ring Using Highly Deformable Smart Materials

Recently, the growing demand of compact energy harvesters for wireless sensor networks has lead to an increasing interest in exploring the energy harvesting capabilities of smart materials. Smart materials are a category of transducer that is able to convert dynamic structural deformations into electricity and vice versa. To investigate the feasibility and the potential of small-scale smart material-based harvesters to obtain energy from ambient fluid environments, interactions between a vortex ring and smart material structure are examined. Vortex rings are a class of coherent structure that is common in nature and act as a canonical representation of vortex structures. Herein, two energy harvesting configurations are considered. First, energy transfer from a passing vortex ring to a cantilevered plate, which is oriented parallel to and offset from the vortex ring's path, is modeled and optimized. The three-dimensional problem is simplified to a two-dimensional problem using a novel method that maintains the loading characteristics of the vortex ring. Two-dimensional Kirchhoff-Love plate theory and two-dimensional potential flow theory are utilized to represent the solid and fluid, respectively. The coupled fluid-structure model is solved simultaneously and validated against published experimental data. Employing this analytical model, the optimization study aims at locating the resonance frequency with respect to the change in fluid and structure parameters. The dimensionless resonance frequency is established as a specific ratio between the plate's fundamental frequency and vortex convective time-scale using a classical moving point load analysis. The result of the optimization study provides a description and empirical formulation of the shift in dimensionless frequency as a result of various fluid and structure parameter adjustments. In the second configuration, the energy harvesting potential of a vortex ring impacting an ionic polymer composite (IPMC) annulus is examined experimentally. The annulus is axis-symmetrically aligned with an incoming vortex ring that is generated by a piston/cylinder setup. The tip deflection of the annular energy harvester is measured with a laser displacement sensor, while the cross-sectional flow field is measured with particle imaging velocimetry and the electrical energy accumulated by the IPMC is estimated with the short-circuit current output. The experimental results unveiled that the annulus is first pulled by the vortex ring low pressure core, and then pushed upon impact. A secondary vortex ring is observed convecting away from the annulus. It is possibly formed out of the vortex induced vorticity at the annulus tip, while the incoming vortex ring is destroyed at impact. The experimental result is found to be in good agreement with an analytical solution

Space station systems: A bibliography with indexes (supplement 6)

This bibliography lists 1,133 reports, articles, and other documents introduced into the NASA scientific and technical information system between July 1, 1987 and December 31, 1987. Its purpose is to provide helpful information to the researcher, manager, and designer in technology development and mission design according to system, interactive analysis and design, structural and thermal analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion, and solar power satellite systems. The coverage includes documents that define major systems and subsystems, servicing and support requirements, procedures and operations, and missions for the current and future Space Station

Solar Module Packaging

While global demand for photovoltaic (PV) modules has increased approximately 45 percent per year over the past decade, PV modules must be durable and inexpensive to compete with traditional energy resources. Often overlooked as a means to improve solar technology, polymer packaging is not only the key to protecting fragile solar cells from environmental factors, but is also the critical path for increasing the power performance of a PV module Solar Module Packaging: Polymeric Requirements and Selection explores current and future opportunities in PV polymeric packaging, emphasizing how it can simultaneously reduce cost, increase weatherability, and improve a PV module’s power. The book offers an insider’s perspective on the manufacturing processes and needs of the solar industry and reveals opportunities for future material development and processing. A broad survey of the polymeric packaging of solar cells, the text covers various classifications of polymers, their material properties, and optimal processing conditions. Taking a practical approach to material selection, it emphasizes industrial requirements for material development, such as cost reduction, increased material durability, improved module performance, and ease of processing. Addressing cost and profitability, the author examines the economics behind polymeric packaging and how it influences the selection process used by solar companies. Suitable for nonspecialists in polymer science, the book provides a basic understanding of polymeric concepts, fundamental properties, and processing techniques commonly used in solar module packaging. It presents guidelines for using polymers in commercial PV modules as well as the tests required to establish confidence in the selection process

MIUS community conceptual design study

The feasibility, practicality, and applicability of the modular integrated utility systems (MIUS) concept to a satellite new-community development with a population of approximately 100,000 were analyzed. Two MIUS design options, the 29-MIUS-unit (option 1) and the 8-MIUS-unit (option 2) facilities were considered. Each resulted in considerable resource savings when compared to a conventional utility system. Economic analyses indicated that the total cash outlay and operations and maintenance costs for these two options were considerably less than for a conventional system. Computer analyses performed in support of this study provided corroborative data for the study group. An environmental impact assessment was performed to determine whether the MIUS meets or will meet necessary environmental standards. The MIUS can provide improved efficiency in the conservation of natural resources while not adversely affecting the physical environment