Architecture for spacecraft operations planning

A system which generates plans for the dynamic environment of space operations is discussed. This system synthesizes plans by combining known operations under a set of physical, functional, and temperal constraints from various plan entities, which are modeled independently but combine in a flexible manner to suit dynamic planning needs. This independence allows the generation of a single plan source which can be compiled and applied to a variety of agents. The architecture blends elements of temperal logic, nonlinear planning, and object oriented constraint modeling to achieve its flexibility. This system was applied to the domain of the Intravehicular Activity (IVA) maintenance and repair aboard Space Station Freedom testbed

Bi-objective modeling approach for repairing multiple feature infrastructure systems

A bi-objective decision aid model for planning long-term maintenance of infrastructure systems is presented, oriented to interventions on their constituent elements, with two upgrade levels possible for each element (partial/full repairs). The model aims at maximizing benefits and minimizing costs, and its novelty is taking into consideration, and combining, the system/element structure, volume discounts, and socioeconomic factors. The model is tested with field data from 229 sidewalks (systems) and compared to two simpler repair policies, of allowing only partial or full repairs. Results show that the efficiency gains are greater in the lower mid-range budget region. The proposed modeling approach is an innovative tool to optimize cost/benefits for the various repair options and analyze the respective trade-offs.info:eu-repo/semantics/publishedVersio

Some Issues Affecting Optimization Models in Water Resource Planning

This paper draws heavily upon my experiences with the MIT-Argentina Study. The purpose of the paper is to bring forth some of the issues that affect the role of optimization models within a water resource planning methodology. Reasonable analysis goes from a problem -- a region or part of a river with certain characteristics -- to model formulation. It is the problem that puts requirements upon the model and in water resources the stochasticity of the real system has caused difficulties in the modeling step. Since optimization plays such an important role in the planning methodology, this paper considers current approaches to handling stochastic elements within optimization. The applicability to a real system like the Tisza is discussed and a new alternative approach is offered

An integrated modeling framework for infrastructure system-of-systems simulation

Design of future hard infrastructure must consider emergent behaviors from cross-system interdependencies. Understanding these interdependencies is challenging due to high levels of integration in high-performance systems and their operation as a collaborative system-of-systems managed by multiple organizations. Existing modeling frameworks have limitations for strategic planning either because important spatial structure attributes have been abstracted out or behavioral models are oriented to shorter-term analysis with a static network structure. This paper presents a formal modeling framework as a first step to integrating infrastructure system models in a system-of-systems simulation addressing these concerns. First, a graph-theoretic structural framework captures the spatial dimension of physical infrastructure. An element's simulation state includes location, parent, resource contents, and operational state properties. Second, a functional behavioral framework captures the temporal dimension of infrastructure operations at a level suitable for strategic analysis. Resource behaviors determine the flow of resources into or out of nodes and element behaviors modify other state including the network structure. Two application use cases illustrate the usefulness of the modeling framework in varying contexts. The first case applies the framework to future space exploration infrastructure with an emphasis on mobile system elements and discrete resource flows. The second case applies the framework to infrastructure investment in Saudi Arabia with an emphasis on immobile system elements aggregated at the city level and continuous resource flows. Finally, conclusions present future work planned for implementing the framework in a simulation software tool.American Society for Engineering Education. National Defense Science and Engineering Graduate Fellowshi

Community and Programmatic Factors Influencing Effecting Use of System Dynamic Models

Despite knowledge of factors that enable effective system dynamics modeling and organizational change, real-life application of these tools in community settings remains challenging and often produces mixed results. We undertook a two-part evaluation of early community use of the ReThink Health Dynamics Model (RTH model). The RTH model is a realistic, but simplified, portrait of a regional health system that supports multisector planning and strategy design. We assessed the contextual characteristics and implementation processes that promoted or under- mined effective engagement with the model in five pilot sites. These learnings were used to refine a community readiness framework (Elements Affecting Modeling Use) that was then used to select and design a sixth community engagement. We use the evaluation results to assess the value of this organizing framework to identify communities ready for engagement with validated system dynamics models. Enabling better community–model matches will accelerate model adoption and health system transformation

Agent Based Modeling and Simulation: An Informatics Perspective

The term computer simulation is related to the usage of a computational model in order to improve the understanding of a system's behavior and/or to evaluate strategies for its operation, in explanatory or predictive schemes. There are cases in which practical or ethical reasons make it impossible to realize direct observations: in these cases, the possibility of realizing 'in-machina' experiments may represent the only way to study, analyze and evaluate models of those realities. Different situations and systems are characterized by the presence of autonomous entities whose local behaviors (actions and interactions) determine the evolution of the overall system; agent-based models are particularly suited to support the definition of models of such systems, but also to support the design and implementation of simulators. Agent-Based models and Multi-Agent Systems (MAS) have been adopted to simulate very different kinds of complex systems, from the simulation of socio-economic systems to the elaboration of scenarios for logistics optimization, from biological systems to urban planning. This paper discusses the specific aspects of this approach to modeling and simulation from the perspective of Informatics, describing the typical elements of an agent-based simulation model and the relevant research.Multi-Agent Systems, Agent-Based Modeling and Simulation

Development of the City Public Service Model on the Basis of Integrated Transport Flow Indicators

The problem of modeling public services based on architectural and planning decisions is considered, the role of traffic in the formation of a model of city services is analyzed. An integrated criterion for the quality of public services is proposed. A method has been developed for determining segmented public services taking into account the transport areas of the city, which will make it possible to evenly disperse public service centers. The basis is a socio-planning organization, as a material-spatial system containing anthropogenic and natural components – the territory and institutions where the functional processes that take place in the urban planning environment take place. The described model has certain versatility, and is simultaneously suitable for characterizing various categories of service institutions. Thus, the task of optimizing the quality of public services in the city is reduced to a mathematical model for which, by setting the basic design criteria, the optimal result can be obtained.On the basis of a questionnaire survey and analysis of statistical data, calculation of traffic intensity, the demand and supply of the level of public services фre studied. The structural elements of this model: population, territory, transport and service institutions, are in dialectical interaction, which is described by the mathematical model in this study. The model is based on the calculation of the minimum population in the service area, which allows to have i-th type establishments using the social potential method, as well as a graph-analytical method in determining the optimal location of service institutions in the city.As a result of the research, a conceptual model of public services for cities is built, a layout of supermarkets in the territory of Uzhhorod and distribution of service areas of these institutions is proposed. This optimization will ensure uniform domestic servicing of the territory, optimal performance indicators of service establishments and minimum average service radii of points

Towards a generic prognostic function of technical multi-component systems taking into account the uncertainties of the predictions of their components

This article presents the first elements of a generic function that assesses the capacity of technical multi-component systems to accomplish the assigned productive tasks from production planning. This assessment is based on the prognostics of their components. It must so be able to process inaccuracies and uncertainties of these prognostics. For its implementation the aimed function combines the Dempster-Shafer theory combined and Bayesian inferences. The paper presents the multi-component system modeling and the inferences for the different identified structures as well as a general algorithm. The final aim of the proposed generic function is to compute decision supports for cooperative maintenance and production management