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AIAA Propulsion and Energy Forum / IEEE Electric Aircraft Technologies Symposium (EATS)

作者： Ilersich, Andrew F. Schau, Kyle A. Oefelein, Joseph C. Steinberg, Adam M. Yano, Masayuki Georgia Inst Technol Inst Aerosp Studies Atlanta GA 30332 USA Georgia Inst Technol Guggenheim Sch Aerosp Engn Atlanta GA 30332 USA Univ Toronto Inst Aerosp Studies Toronto ON M3H 5T6 Canada

ISBN: (数字)9781624106118

ISBN: (纸本)9781624106118

We present and assess a method to reduce the computational cost of performing data assimilation (DA) for reacting flow in multiple-query scenarios, where we consider several scenarios with similar underlying dynamics. We focus on ensemble-based DA, in particular the ensemble Kalman filter (EnKF). The accuracy of the EnKF, which depends on the quality of the sample covariance, improves with the ensemble size, but so does its computational cost. To reduce the ensemble size while maintaining accurate covariance, we propose a data-driven approach to augment the covariance based on the statistical behavior learned from model evaluations. We assess our augmentation method using a one-dimensional model problem and a synthetic reacting flowcase. We showin both bases that ensemble size, and thus computational cost, may be reduced by a factor of three to four while maintaining accuracy.

关键词： Turbulent Reacting Flow Kalman Filter Reynolds Averaged Navier Stokes Turbulent Combustion probability density functions Meteorology Conservation Equations Gas Turbine Combustor

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Multi-hypothesis Test Detection for Star Tracking Systems

Multi-hypothesis Test Detection for Star Tracking Systems

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AIAA Science and Technology Forum and Exposition (AIAA SciTech Forum)

作者： Kirk, Jordan T. Cain, Stephen C. Air Force Inst Technol US Air Force Wright Patterson AFB OH 45433 USA Air Force Inst Technol Dept Elect & Comp Engn AFIT Wright Patterson AFB OH 45433 USA

ISBN: (数字)9781624106095

ISBN: (纸本)9781624106095

The pointing accuracy requirements for space vehicles is constantly increasing;however, the ability to point the space vehicle without a beacon is constrained by the accuracy of the current orientation information. Orienting the space vehicle in reference to fixed star positions allows for a high degree of accuracy, but this research aims to determine whether or not using a multi-hypothesis test (MHT) to detect the stars will yield increased accuracy compared to the presently used binary hypothesis test (BHT). To compare the two methods, an experiment is run by gathering images of illuminated pixels on a computer monitor to represents stars. The MHT and BHT both process the same set of images and convert the detections into estimates of the rotation angles. The method that yields less variance in the estimated rotation angles is determined to be superior. The MHT produced 18.5% less variance in the estimation of the x axis rotation angle, 28.1% less variance in the estimation of the y axis rotation angle, and 46.8% less variance in the estimation of the z axis rotation angle compared to the BHT.

关键词： Charge Coupled Device Satellites Star Tracker Telescopes National Aeronautics and Space Administration Singular Value Decomposition Defense Advanced Research Projects Agencies Earth probability density functions Optical Transfer Function

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Anomaly Detection, Active Learning, Precursor Identification, and Human Knowledge for Autonomous System Safety

Anomaly Detection, Active Learning, Precursor Identification...

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AIAA Science and Technology Forum and Exposition (AIAA SciTech Forum)

作者： Oza, Nikunj C. Bradner, Kevin M. Iverson, David L. Sahasrabhojanee, Adwait Wolfe, Shawn R. NASA Intelligent Syst Div Ames Res Ctr Mail Stop 269-3 Moffett Field CA 94035 USA

ISBN: (数字)9781624106095

ISBN: (纸本)9781624106095

The project Autonomy Teaming and TRajectories for Complex Trusted Operational Reliability (ATTRACTOR) [1] researched and developed Artificial Intelligence with application to multi-Unmanned Aerial Systems (UAS) missions. Such missions, like other complex systems-of-systems, are likely to have previously-unknown, safety relevant anomalies occur due to many possible factors including system failures or degradations, emergent behavior, changes in the environment in which the systems operate, changes in the way the systems are operated. We discuss the application of anomaly detection, active learning, and precursor identification to identify such anomalies and the conditions under which they are more likely to appear. We demonstrate results on simulated multi-UAS missions that show promise to be applied to real missions.

关键词： Anomaly Detection System Autonomous Systems Artificial Intelligence Unmanned Aerial Systems Data Science Support Vector Machine Thermal Protection System probability density functions Long Short Term Memory Telemetry

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An Expert Data-Driven Air Combat Maneuver Model Learning Approach

An Expert Data-Driven Air Combat Maneuver Model Learning App...

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AIAA Science and Technology Forum and Exposition (AIAA SciTech Forum)

作者： Park, Su-Jeong Park, Soon-Seo Choi, Han-Lim Ai, Kyeong-Soo Kim, Young-Gon Korea Adv Inst Sci & Technol Dept Aerosp Engn Daejeon 34141 South Korea Hanwha Syst Av R&D Ctr Seongnam 13524 South Korea

ISBN: (数字)9781624106095

ISBN: (纸本)9781624106095

This paper considers the problem of a learning air combat maneuver model when an expert pilot's trajectories are given. Most studies of imitation learning require large amount of data for training and have to interact with real environments, even under uncertain dynamics of enemy aircraft. Thus, we propose a new approach to solve this problem by : (i) training an internal model that can represent future states and imitate the maneuvering of an expert using MDN-RNN and a controller and (ii) generating expert-like trajectories via a dreaming process, which imagines an engagement situation in a hypothetical environment model. This approach does not require interaction with the real environment nor a reward function for training. We demonstrate the similarity between the expert trajectory and the trajectory reconstructed by the proposed model.

关键词： Air Combat Maneuvering Recurrent Neural Network Trajectory Optimization Pilot Inverse Reinforcement Learning Heading Angle Linear Quadratic Regulator Monte Carlo Experiment Unmanned Aircraft System probability density functions

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Integration of Multi-Fidelity Models with Agent-Based Simulation for System of Systems

Integration of Multi-Fidelity Models with Agent-Based Simula...

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AIAA Aviation Forum and Exposition

作者： Schon, Sofia Marcust, Carina Amadori, Kristian Jouanne, Christopher Linkoping Univ Div Prod Realisat Dept Management & Engn S-58183 Linkoping Ostergotland Sweden Saab Aeronaut S-58188 Linkoping Ostergotland Sweden

ISBN: (数字)9781624106101

ISBN: (纸本)9781624106101

System of Systems (SoS) are everywhere, either created and directed by an organization or simply emerging to fulfill a need. SoS consist of many independent Constituent Systems (CS) with their own life cycles and behavior. One of the big challenges with studying SoS is building models to support the analysis of these large complex systems. For existent SoS, it may be tempting to use available models from subsequent levels and connect them in a common framework, rather than creating new models tailored for the SoS analysis. Typically, the already existing models often have a high level of fidelity and have been created from a certain point of view to best fit its purpose. This paper shows that a framework with higher fidelity models on Sub-Systems (SS) level will impact the performance on SoS level but also take longer time to converge and thus need more simulations in order for the results to be trusted. With an holistic approach to the development of SoS, we use hierarchical integration of CS and SS models to provide inputs to the simulation on SoS level. Using maritime Search and Rescue (SAR) as a case study, the mission performance of two aircraft searching for a lost life raft through Agent Based Simulation (ABS). Two cases are compared where one of them has a higher fidelity representation of the sensor model. Through the case study it is possible to investigate the impact of model fidelity on the SS level to the simulation results on SoS level. The two cases simulate the same scenario but still show a difference in mission performance. A convergence analysis show that with the the High Fidelity Models (HFM) the simulation takes slightly longer to converge. This paper is the beginning of a multi-fidelity model library that will be used to explore the impact of model fidelity on all the levels of SoS and from that find general methods for choosing model fidelity when analyzing SoS.

关键词： Sensors Convergence Analysis Unmanned Aerial Vehicle MATLAB Aircraft Performance probability density functions Fixed Wing Aircraft Fuel Consumption Ocean Currents Aeroplane

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Direct molecular simulation of dissociating oxygen under adiabatic and normal shock wave conditions

Direct molecular simulation of dissociating oxygen under adi...

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AIAA Science and Technology Forum and Exposition (AIAA SciTech Forum)

作者： Torres, Erik Schwartzentruber, Thomas E. Univ Minnesota Dept Aerosp Engn & Mech 107 Akerman Hall110 Union St SE Minneapolis MN 55455 USA

ISBN: (数字)9781624106095

ISBN: (纸本)9781624106095

We present directmolecular simulations (DMS) of rovibrational excitation and dissociation of oxygen in a constant-volume, adiabatic reactor and across a normal shock wave. This setup aims to reproduce the nonequilibrium conditions in the shock tube experiments of Ibraguimova et al. (JChemPhys 2013). We examine internal energy and vibrational population distributions of the O-2 molecules at several stages of the process and observe overpopulated and depleted populations in the high-energy tail at different stages of dissociation. In the adiabatic simulations we observe how the characteristic length scales for vibrational relaxation and dissociation are affected by lowering the total enthalpy of the upstream gas. We then compare vibrational temperatures from our simulations with those inferred from the shock tube tests and obtain reasonable agreement. Finally, we compare the adiabatic reactor DMS calculations with the equivalent normal shock simulations. Our assessment is that, while the adiabatic reactor does a reasonable job of reproducing the thermo-chemical state of the shocked gas, it actually generates more severe initial nonequilibrium conditions than what is observed in the normal shock.

关键词： Normal Shock Wave Static Enthalpy Thermodynamic Properties Free Stream Velocity Direct Simulation Monte Carlo Shock Wave Profiles Chemical Energy Energy Distribution probability density functions Velocity Profiles

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ANALYTICAL PERFORMANCE ANALYSIS OF THE M2M WIRELESS LINKWITH AN ANTENNA SELECTION SYSTEM OVER INTERFERENCELIMITED DISSIMILAR COMPOSITE FADING ENVIRONMENTS

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INTERNATIONAL JOURNAL OF APPLIED MATHEMATICS AND COMPUTER SCIENCE 2022年第4期32卷 569-582页

作者： Dosic, Danijel Milic, Dejan Kontrec, Natasa Stefanovic, Caslav Milosavljevic, Sroan Stefanovic, Dusan M. Univ Pristina Kosovska Mitrovica Fac Sci & Math Lole Ribara 29 Kosovska Mitrovica 38220 Serbia Univ Nis Fac Elect Engn A Medvedeva 14 Nish 18000 Serbia Charles III Univ Madrid Dept Signal Theory & Commun Leganes 28911 Spain Univ Pristina Kosovska Mitrov Fac Econ Kolasinska 156 Kosovska Mitrovica 38220 Serbia Coll Appl Tech Sci Nis A Medvedeva 20 Nish 18000 Serbia

This paper considers direct mobile-to-mobile (M2M) communications with a dual antenna selection (AS) system at a destination mobile node (DMN) in interference limited, dissimilar composite fading environments. In particular, we model dissimilar interference limited signals at the inputs of the dual branch AS system as (i) the ratio of two Nakagami-m (N) random variables (RVs) at the first branch and (ii) the ratio of two Rice RVs at the second branch, in order to account for non line-of-sight (NLOS) and line-of-sight (LOS) communications, respectively. Moreover, we assume variable powers of the desired as well as interference signals at the output of the DMN in order to account for the impact of shadowing. For the proposed model, we derive probability density functions, cumulative distribution functions, outage probabilities and average level crossing rates. The derived statistical results are evaluated for all the statistical measures considered and are graphically presented in order to provide insight into the impact of composite fading severities and LOS factors for the desired signal, as well as for the interference, on the system performances.

关键词： mobile-to-mobile communication vehicle-to-vehicle communication Nakagami-m fading Rice fading probability density functions cumulative density functions

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A New Accurate Clustering Approach for Detecting Different Densities in High Dimensional Data 23rd

A New Accurate Clustering Approach for Detecting Different D...

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23rd International Conference on Big Data Analytics and Knowledge Discovery (DaWaK)

作者： El Malki, Nabil Cugny, Robin Teste, Olivier Ravat, Franck IRIT Toulouse France

ISBN: (纸本)9783030865344;9783030865337

Clustering is a data analysis method for extracting knowledge by discovering groups of data called clusters. density-based clustering methods have proven to be effective for arbitrary-shaped clusters, but they have difficulties to find low-density clusters, near clusters with similar densities, and clusters in high-dimensional data. Our proposal consists in a new clustering algorithm based on spatial density and probabilistic approach. Sub-clusters are constituted using spatial density represented as probability density function (p.d. f) of pairwise distances between points. To agglomerate similar sub-clusters we combine spatial and probabilistic distances. We show that our approach outperforms main state-of-the-art density-based clustering methods on a wide variety of datasets.

关键词： density-based clustering probability density functions Wasserstein distance

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Probabilistic Assessment of Buildings Subjected to Multi-Level Earthquake Loading Based on the PBSD Concept

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BUILDINGS 2022年第11期12卷 1942页

作者： Monjardin-Quevedo, J. Guadalupe Valenzuela-Beltran, Federico Reyes-Salazar, Alfredo Leal-Graciano, J. Martin Torres-Carrillo, Xochitl G. Gaxiola-Camacho, J. Ramon Autonomous Univ Sinaloa Dept Earth & Space Sci Culiacan 80013 Sinaloa Mexico Autonomous Univ Sinaloa Dept Civil Engn Culiacan 80013 Sinaloa Mexico

An alternative probabilistic assessment of buildings excited by multi-level seismic loading is presented in this paper. This evaluation is developed for both steel and reinforced concrete buildings using the Performance-Based Seismic Design (PBSD) concept. The methodology implements probability density functions (PDFs) of inter-story drifts to extract structural risk in terms of the reliability index. Ten buildings of steel and reinforced concrete, respectively, are designed considering different locations in Mexico. Then, each structure is excited by ground motions representing different earthquake intensity levels for three performance levels: immediate occupancy, life safety, and collapse prevention. The deterministic seismic response of buildings is extracted using the finite element software OpenSees. Based on the results, it can be stated that the probabilistic assessment technique represents an efficient approach for extracting the seismic risk of structures using PDFs of inter-story drifts. Lastly, it is demonstrated that the evaluation of buildings following PBSD is a step in the right direction, moving from traditional deterministic design concepts to probabilistic philosophies.

关键词： performance-based seismic design probability density functions reliability index structural risk ground motion selection performance levels earthquake-resistant design

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Wind Energy Potential Assessment of some Sites in Burundi using Statistical Modelling 8

Wind Energy Potential Assessment of some Sites in Burundi us...

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IEEE PES/IAS PowerAfrica Conference

作者： Placide, Gatoto Lollchund, Michel Roddy Dalso, Gace Athanase Univ Rwanda Ecole Normale Super Burundi ACE ESD Kigali Rwanda Univ Mauritius Dept Phys Reduit Mauritius Univ Rwanda Dept Phys Kigali Rwanda

ISBN: (纸本)9781665403115

The aim of this study is to estimate the wind energy potential at four locations in Burundi: Bujumbura, Gisozi, Gitega and Mpota. For this endeavour, some commonly used statistical probability distribution functions (PDFs) (i.e. Burr, Gamma, Lognormal, Normal, Rayleigh and Weibull) are assessed in the modelling of around 20 years of daily wind speed data measured at the four locations. The parameters for each PDF are estimated using the Maximum likelihood method and goodness-of-fit tests are used to assess how well the PDFs fit the data. It is found that the Burr distribution fits all the data at 0.05 significance level. Finally, computed Burr parameters for monthly wind speed datasets are used to estimate the mean monthly wind power density (WPD) at each location. Results obtained show that Bujumbura has high potential for wind energy harvesting.

关键词： Goodness-of-fit test probability density functions wind speed wind energy potential

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