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

Federated Simulation and Gaming Framework for a Decentralized Space-Based Resource Economy

Future human space exploration will require large amounts of resources for shielding and building materials, propellants, and consumables. A space-based resource economy could produce, transport, and store resource at distributed locations such as the lunar surface, stable orbits, or Lagrange points to avoid Earth's deep gravity well. Design challenges include decentralized operation and management and socio-technical complexities not commonly addressed by modeling and simulation methods. This paper seeks to tackle these challenges by applying aspects of military wargaming to promote effective communication between decision-makers. A software architecture for federated simulation based on IEEE-1516 (HLA-Evolved) is presented in the context of multiple lunar in-situ resource production processes, resource depots, and intermediate transportation. The federation-level framework identifies interfaces between simulation models (federates), focusing on persistent assets (elements) and resources exchanged. Future work will develop the federated resource economy model and evaluate with decision-makers playing the roles of competing and collaborating players.United States. Dept. of DefenseUnited States. Air Force Office of Scientific ResearchAmerican Society for Engineering Education. National Defense Science and Engineering Graduate Fellowship (32 CFR 168a

Comparative Usability Study of Two Space Logistics Analysis Tools

Future space exploration missions and campaigns will require sophisticated tools to help plan and analyze logistics. To encourage their use, space logistics tools must be usable: a design concept encompassing terms such as efficiency, effectiveness, and satisfaction. This paper presents a usability study of two such tools: SpaceNet, a discrete event simulation tool and a comparable spreadsheet-based tool. The study follows a randomized orthogonal design having within-subjects evaluation of the two tools with 12 volunteer subjects (eight subjects with space backgrounds, four without). Each subject completed two sessions of testing, each with a 30-45 minute tutorial and a two-part space exploration scenario. The first part tests the creation a model to verify a simple uncrewed mission to lunar orbit. The second part tests the evaluation of an existing model to improve the effectiveness of a crewed mission to the lunar surface. The subjects completed a questionnaire after each session and a semi-structured interview following the second session. The study results indicate that the SpaceNet tool is more efficient for portions of the model creation task including modeling multi-burn transports and the spreadsheet tool is more effective for the model evaluation task. Qualitative evaluation indicates subjects liked the graphical nature and error-detection of the SpaceNet tool, but felt it took too long to edit information and appeared as a “black box.” Subjects liked the ability to view the entire model state within the spreadsheet tool, however were concerned with limited dynamic state feedback and underlying modeling assumptions. Future tools should combine the best features, including allowing modification of the entire model from a single interface, providing visibility of underlying logic, and integrated graphical and error-checking feedback.United States. Dept. of DefenseUnited States. Air Force Office of Scientific ResearchAmerican Society for Engineering Education. National Defense Science and Engineering Graduate Fellowship32 CFR 168aSamsung Fellowshi

Matrix Methods for Optimal Manifesting of Multinode Space Exploration Systems

http://www1.aiaa.org/content.cfm?pageid=318, Presented at the AIAA Space 2010 Conference and ExhibitionAnaheim, CA, 30 August–2 September 2010.This paper presents matrix-based methods for determining optimal cargo manifests for space exploration. An exploration system is defined as a sequence of in-space and on-surface transports between multiple nodes coupled with demands for resources. The goal is to maximize value and robustness of exploration while satisfying logistical demands and physical constraints at all times. To reduce problem complexity, demands are abstracted to a single class of resources, and one metric (e.g., mass or volume) governs capacity limits. Matrices represent cargo carried by transports, cargo used to satisfy demands, and cargo transferred to other transports. A system of equations enforces flow conservation, demand satisfaction, and capacity constraints. Exploration system feasibility is evaluated by determining if a solution exists to a linear program or network-flow problem. Manifests are optimized subject to an objective function using linear or nonlinear programming techniques. In addition to modeling the manifesting problem, a few metrics such as the transport criticality index are formulated to enable analysis and interpretation. The proposed matrix manifest modeling methods are demonstrated with a notional lunar exploration system composed of 32 transports, including eight cargo and nine crewed landings at an outpost at the lunar south pole and several surface excursions to Malapert Crater and Schrödinger Basin. It is found that carry-along and prepositioning logistics strategies yield different manifesting solutions in which transport criticality varies. For the lunar scenario, transport criticality is larger for a prepositioning strategy (mean value of 3.02), as compared with an alternative carry-along case (mean value of 1.99)

Process-oriented evaluation of user interactions in integrated system analysis tools

When computer-based tools are used for analysis of complex systems, the design of user interactions and interfaces becomes an essential part of development that determines the overall quality. The objective of this study is to investigate the processes and results of user interactions with integrated analysis tools to synthesize design implications for future tool development. In this study, two space exploration logistics tools are compared in a controlled user experiment. Through a comparative usability analysis, this study evaluated user performance and perception to provide design implications for future integrated analysis tools. For a comprehensive evaluation, multiple methods were used for data collection, including observation, questionnaire and interview. In addition to a result-oriented performance analysis, a process-oriented approach was used for analyzing patterns in user behaviors and errors. Results are presented with reference to the related features embedded in the interfaces of the two tools. Based on the comparative results, synthesized design insights for hierarchical structure, model transparency, automation, and visualization and feedback are discussed for integrated analysis tools in general.American Society for Engineering Education. National Defense Science and Engineering Graduate Fellowshi

Multi-stakeholder Interactive Simulation for Federated Satellite Systems

Federated satellite systems (FSS) are a new class of space-based systems which emphasize a distributed architecture. New information exchanging functions among FSS members enable data transportation, storage, and processing as on-orbit services. As a system-of-systems, however there are significant technical and social barriers to designing a FSS. To mitigate these challenges, this paper develops a multi-stakeholder interactive simulation for use in future design activities. An FSS simulation interface is defined using the High Level Architecture to include orbital and surface assets and associated transmitters, receivers, and signals for communication. Sample simulators (federates) using World Wind and Orekit open source libraries are applied in a prototype simulation (federation). The application case studies a conceptual FSS using the International Space Station (ISS) as a service platform to serve Earth-observing customers in sun-synchronous orbits (SSO). Results identify emergent effects between FSS members including favorable ISS power conditions and potential service bottlenecks to serving SSO customers

The Modern Irrationalities of American Criminal Codes: An Empirical Study of Offense Grading

The Model Penal Code made great advances in clarity and legality, moving most of the states from a mix of common law and ad hoc statutes to the modern American form of a comprehensive, succinct code that has served as a model around the world. Yet the decades since the wave of Model Code-based codifications have seen a steady degradation of American codes brought on by a relentless and accelerating rate of criminal law amendments that ignore the style, format, and content of the existing codes. The most damaging aspect of this trend is the exponentially increasing number of offense grading irrationalities found in most modern American codes. This Article documents the practical and prudential importance of getting offense grading right – that is, having the grade of each offense or suboffense reflect its relative seriousness in relation to all other offenses – then illustrates just how wrong things have gone, using a case study of offense grading in Pennsylvania, one of the better modern American codes. The critique of Pennsylvania, and its conclusions, does not rely upon the value judgments of the authors but rather upon an empirical study of the judgments of Pennsylvania residents regarding the relative seriousness of more than a hundred existing Pennsylvania offenses. The results suggest a startling conflict between the law\u27s grading judgments and those of the community it governs, as well as a variety of kinds of logical irrationalities and internal inconsistencies. The process by which these grading irrationalities have been and continue to be created is examined, and solutions for fixing and, perhaps, avoiding these problems in the future, are explored

City.Net IES: A sustainability-oriented energy decision support system

A city's energy system processes, as well as the interactions of the energy system with other systems in a city are imperative in creating a comprehensive energy decision support system due to the interdependencies between critical segments of the system. City.Net is a sustainability-oriented decision support system that represents the energy, water, waste, transportation and building systems in a city while taking into consideration the integration and interdependencies that exist between these systems. This paper, which is focused on the integrated energy infrastructure system of a sustainable city, builds on the previous work which employs hierarchical decomposition and multi-domain formulation for the design of complex sustainable systems. The City.Net energy system encompasses the generation, transmission, distribution and consumption of energy in different forms, in several domains and at diverse scales in a city. Also, the interactions of the energy system with other aforementioned systems are incorporated in City.Net. The result is a scalable and flexible energy decision support system which can be simulated and used as a sustainability-analysis tool, encompassing environmental, social and economic sustainability

Observation of Quantum Effects in sub Kelvin Cold Reactions

There has been a long-standing quest to observe chemical reactions at low temperatures where reaction rates and pathways are governed by quantum mechanical effects. So far this field of Quantum Chemistry has been dominated by theory. The difficulty has been to realize in the laboratory low enough collisional velocities between neutral reactants, so that the quantum wave nature could be observed. We report here the first realization of merged neutral supersonic beams, and the observation of clear quantum effects in the resulting reactions. We observe orbiting resonances in the Penning ionization reaction of argon and molecular hydrogen with metastable helium leading to a sharp increase in the absolute reaction rate in the energy range corresponding to a few degrees kelvin down to 10 mK. Our method is widely applicable to many canonical chemical reactions, and will enable a breakthrough in the experimental study of Quantum Chemistry

The rovibrational spectrum of BeH, MgH and CaH at high temperatures in the X 2Σ+X\,{}^2\Sigma^+ state: a theoretical study

Accurate line lists for three molecules, BeH, MgH and CaH, in their ground electronic states are presented. These line lists are suitable for temperatures relevant to exoplanetary atmospheres and cool stars (up to 2000K). A combination of empirical and \textit{ab initio} methods is used. The rovibrational energy levels of BeH, MgH and CaH are computed using the programs Level and DPotFit in conjunction with `spectroscopic' potential energy curves (PECs). The PEC of BeH is taken from the literature, while the PECs of CaH and MgH are generated by fitting to the experimental transition energy levels. Both spin-rotation interactions (except for BeH, for which it is negligible) and non-adiabatic corrections are explicitly taken into account. Accurate line intensities are generated using newly computed \textit{ab initio} dipole moment curves for each molecule using high levels of theory. Full line lists of rotation-vibration transitions for $^9$BeH, $^{24}$MgH, $^{25}$MgH, $^{26}$MgH and $^{40}$CaH are made available in an electronic form as supplementary data to this article and at \url{www.exomol.com}.Comment: MNRAS (in press