10,152 research outputs found
Site Diversity in Downlink Optical Satellite Networks Through Ground Station Selection
Recent advances have shown that satellite communication (SatCom) will be an
important enabler for next generation terrestrial networks as it can provide
numerous advantages, including global coverage, high speed connectivity,
reliability, and instant deployment. An ideal alternative for radio frequency
(RF) satellites is its free-space optical (FSO) counterpart. FSO or laser
SatCom can mitigate the problems occurring in RF SatCom, while providing
important advantages, including reduced mass, lower consumption, better
throughput, and lower costs. Furthermore, laser SatCom is inherently resistant
to jamming, interception, and interference. Owing to these benefits, this paper
focuses on downlink laser SatCom, where the best ground station (GS) is
selected among numerous candidates to provide reliable connectivity and maximum
site diversity. To quantify the performance of the proposed scheme, we derive
closed-form outage probability and ergodic capacity expressions for two
different practical GS deployment scenarios. Furthermore, asymptotic analysis
is conducted to obtain the overall site diversity gain, and aperture averaging
is studied to illustrate the impact of aperture diameter on the overall
performance. Finally, important design guidelines that can be useful in the
design of practical laser SatComs are outlined
Performance Measures to Assess Resiliency and Efficiency of Transit Systems
Transit agencies are interested in assessing the short-, mid-, and long-term performance of infrastructure with the objective of enhancing resiliency and efficiency. This report addresses three distinct aspects of New Jersey’s Transit System: 1) resiliency of bridge infrastructure, 2) resiliency of public transit systems, and 3) efficiency of transit systems with an emphasis on paratransit service.
This project proposed a conceptual framework to assess the performance and resiliency for bridge structures in a transit network before and after disasters utilizing structural health monitoring (SHM), finite element (FE) modeling and remote sensing using Interferometric Synthetic Aperture Radar (InSAR). The public transit systems in NY/NJ were analyzed based on their vulnerability, resiliency, and efficiency in recovery following a major natural disaster
LiDAR-based Weather Detection: Automotive LiDAR Sensors in Adverse Weather Conditions
Technologische Verbesserungen erhöhen den Automatisierungsgrad von Fahrzeugen. Der natürliche Schritt ist dabei, den Fahrer dort zu unterstützen, wo er es am meisten wünscht: bei schlechtem Wetter. Das Wetter beeinflusst alle Sensoren, die zur Wahrnehmung der Umgebung verwendet werden, daher ist es entscheidend, diese Effekte zu berücksichtigen und abzuschwächen.
Die vorliegende Dissertation konzentriert sich auf die gerade entstehende Technologie der automobilen Light Detection and Ranging (LiDAR)-Sensoren und trägt zur Entwicklung von autonomen Fahrzeugen bei, die in der Lage sind, unter verschiedenen Wetterbedingungen zu fahren.
Die Grundlage ist der erste LiDAR-Punktwolken-Datensatz mit dem Schwerpunkt auf schlechte Wetterbedingungen, welcher punktweise annonatatierte Wetterinformationen enthält, während er
unter kontrollierten Wetterbedingungen aufgezeichnet wurde. Dieser Datensatz wird durch eine neuartige Wetter-Augmentation erweitert, um realistische Wettereffekte erzeugen zu können.
Ein neuartiger Ansatz zur Klassifizierung des Wetterzustands
und der erste CNN-basierte Entrauschungsalgorithmus werden entwickelt. Das Ergebnis ist eine genaue Vorhersage des Wetterstatus und eine Verbesserung der Punktwolkenqualität.
Kontrollierte Umgebungen unter verschiedenen Wetterbedingungen ermöglichen die Evaluierung der oben genannten Ansätze und liefern wertvolle Informationen für das automatisierte und autonome Fahren
Aeronautical Engineering: A continuing bibliography, supplement 120
This bibliography contains abstracts for 297 reports, articles, and other documents introduced into the NASA scientific and technical information system in February 1980
Aeronautics and space report of the President, 1982 activities
Achievements of the space program are summerized in the area of communication, Earth resources, environment, space sciences, transportation, aeronautics, and space energy. Space program activities of the various deprtments and agencies of the Federal Government are discussed in relation to the agencies' goals and policies. Records of U.S. and world spacecraft launchings, successful U.S. launches for 1982, U.S. launched applications and scientific satellites and space probes since 1975, U.S. and Soviet manned spaceflights since 1961, data on U.S. space launch vehicles, and budget summaries are provided. The national space policy and the aeronautical research and technology policy statements are included
- …