12,689 research outputs found
Application of advanced technology to space automation
Automated operations in space provide the key to optimized mission design and data acquisition at minimum cost for the future. The results of this study strongly accentuate this statement and should provide further incentive for immediate development of specific automtion technology as defined herein. Essential automation technology requirements were identified for future programs. The study was undertaken to address the future role of automation in the space program, the potential benefits to be derived, and the technology efforts that should be directed toward obtaining these benefits
Deployable antenna demonstration project
Test program options are described for large lightweight deployable antennas for space communications, radar and radiometry systems
Ground collision avoidance systems on United States Air Force aircraft
Thesis (S.M.)--Massachusetts Institute of Technology, Sloan School of Management, 1995.Includes bibliographical references (p. 91-92).This thesis examines a specific type of USAF aircraft mishaps - Controlled Flight Into Terrain (CFIT) mishaps. The thesis presents data on CFIT mishaps, causes, and efforts to reduce CFIT mishaps through the development and adoption of Ground Collision Avoidance Systems (GCAS) or similar designs - Ground Proximity Warning Systems (GPWS). GPWS exist today on some USAF aircraft, but many times these systems are inadequate (as evidenced by the continued occurrence of CFIT mishaps). Both ongoing and future initiatives by the USAF to adopt and develop better GPWS/GCAS systems were studied. An analysis was performed which studied the cost to the USAF (and the U.S. taxpayer) as a result of CFIT mishaps, and compared with an analysis of the cost to develop and implement improved GPWS/GCAS systems. The results show conclusively that installing GCAS/GPWS on a majority of USAF aircraft is cost effective. Technology exist today which could improve existing GPWS performance, and although efforts to improve GPWS are moving forward, some resistance does exist. Possible reasons for resistance of GCAS/GPWS adoption were studied and several recommendations were made on how to improve the adoption of these systems within the USAF.by Jan W. Scofield.S.M
Airborne Wind Shear Detection and Warning Systems. Second Combined Manufacturers' and Technologists' Conference, part 1
The Second Combined Manufacturers' and Technologists' Conference hosted jointly by NASA Langley (LaRC) and the Federal Aviation Administration (FAA) was held in Williamsburg, Virginia, on October 18 to 20, 1988. The purpose of the meeting was to transfer significant, ongoing results gained during the second year of the joint NASA/FAA Airborne Wind Shear Program to the technical industry and to pose problems of current concern to the combined group. It also provided a forum for manufacturers to review forward-look technology concepts and for technologists to gain an understanding of the problems encountered by the manufacturers during the development of airborne equipment and the FAA certification requirements
Integrating the Non-Line of Sight Launching System (NLOS-LS) in the United States Navy
The global war on terror emphasizes the need for a weapon system that can improve the self-defense capability of the U.S Navy ship against small surface craft threats. This MSSE Capstone Project investigated the feasibility of integrating the Non-Line of Sight Launching System (NLOS-LS) onto U.S. Navy ships. In particular, the focus of the project was on the DDG-51 class ships. The NLOS-LS was originally designed to provide support to Army ground forces against over the horizon threats. The U.S. Navy recognizes the prospect of this weapon in an at-sea environment. The capability of the system has been proven through its developmental testing to date and illustrates the potential to the U.S. Navy for ship defense. System integration involves incorporating a stand-alone, land-based system onto a ship with an existing shipboard combat system. This report addresses the top-level integration issues, such as the physical installation and combat system integration, and provides recommendations related to some important concerns that include interface analysis, functional analysis, system behavior, and physical installation. This analysis concludes with a notional implementation for many issues and provides a risk analysis for those issues. It also identifies many integration areas requiring further research.http://archive.org/details/integratingnonli10945692
Remote sensing in the coastal and marine environment. Proceedings of the US North Atlantic Regional Workshop
Presentations were grouped in the following categories: (1) a technical orientation of Earth resources remote sensing including data sources and processing; (2) a review of the present status of remote sensing technology applicable to the coastal and marine environment; (3) a description of data and information needs of selected coastal and marine activities; and (4) an outline of plans for marine monitoring systems for the east coast and a concept for an east coast remote sensing facility. Also discussed were user needs and remote sensing potentials in the areas of coastal processes and management, commercial and recreational fisheries, and marine physical processes
The EarthCARE satellite: the next step forward in global measurements of clouds, aerosols, precipitation, and radiation
The collective representation within global models of aerosol, cloud, precipitation, and their radiative properties remains unsatisfactory. They constitute the largest source of uncertainty in predictions of climatic change and hamper the ability of numerical weather prediction models to forecast high-impact weather events. The joint European Space Agency (ESA)–Japan Aerospace Exploration Agency (JAXA) Earth Clouds, Aerosol and Radiation Explorer (EarthCARE) satellite mission, scheduled for launch in 2018, will help to resolve these weaknesses by providing global profiles of cloud, aerosol, precipitation, and associated radiative properties inferred from a combination of measurements made by its collocated active and passive sensors. EarthCARE will improve our understanding of cloud and aerosol processes by extending the invaluable dataset acquired by the A-Train satellites CloudSat, Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), and Aqua. Specifically, EarthCARE’s cloud profiling radar, with 7 dB more sensitivity than CloudSat, will detect more thin clouds and its Doppler capability will provide novel information on convection, precipitating ice particle, and raindrop fall speeds. EarthCARE’s 355-nm high-spectral-resolution lidar will measure directly and accurately cloud and aerosol extinction and optical depth. Combining this with backscatter and polarization information should lead to an unprecedented ability to identify aerosol type. The multispectral imager will provide a context for, and the ability to construct, the cloud and aerosol distribution in 3D domains around the narrow 2D retrieved cross section. The consistency of the retrievals will be assessed to within a target of ±10 W m–2 on the (10 km)2 scale by comparing the multiview broadband radiometer observations to the top-of-atmosphere fluxes estimated by 3D radiative transfer models acting on retrieved 3D domains
Development and Evaluation of a Multistatic Ultrawideband Random Noise Radar
This research studies the AFIT noise network (NoNET) radar node design and the feasibility in processing the bistatic channel information of a cluster of widely distributed noise radar nodes. A system characterization is used to predict theoretical localization performance metrics. Design and integration of a distributed and central signal and data processing architecture enables the Matlab®-driven signal data acquisition, digital processing and multi-sensor image fusion. Experimental evaluation of the monostatic localization performance reveals its range measurement error standard deviation is 4.8 cm with a range resolution of 87.2(±5.9) cm. The 16-channel multistatic solution results in a 2-dimensional localization error of 7.7(±3.1) cm and a comparative analysis is performed against the netted monostatic solution. Results show that active sensing with a low probability of intercept (LPI) multistatic radar, like the NoNET, is capable of producing sub-meter accuracy and near meter-resolution imagery
M-sequenze based ultra-wideband radar and its application to crack detection in salt mines
Die vorliegende Dissertation beschreibt einen innovativen ultra-breitband
(UWB)elektromagnetischen Sensor basierend auf einem
Pseudo-Rauschverfahren.Der Sensor wurde für zerstörungsfreies Testen in
zivilen Anwendungen entwickelt.Zerstörungsfreies Testen entwickelt sich zu
einem immer wichtiger werdenden Bereich in Forschung und Entwicklung. Neben
unzähligen weiteren Anwendungen und Technologien, besteht ein primäres
Aufgabenfeld in der Ăśberwachung und Untersuchung von Bauwerken und
Baumaterialien durch berĂĽhrungslose Messung aus der Ferne.Diese Arbeit
konzentriert sich auf das Beispiel der Auflockerungszone im Salzgestein.Der
Hintergrund und die Notwendigkeit, den Zustand der oberflächennahen
Salzschichten in Salzminen kennen zu mĂĽssen, werden beleuchtet und die
Messaufgabe anhand einfacher theoretischer Ăśberlegungen beschrieben. Daraus
werden die Anforderungen fĂĽr geeignete UWB Sensoren abgeleitet. Die
wichtigsten Eigenschaften sind eine sehr hohe Messband breite sowie eine sehr
saubere Systemimpulsantwort frei von systematischen Gerätefehlern. Beide
Eigenschaften sind notwendig, um die schwachen RĂĽckstreuungen
der Auflockerungen trotz der unvermeidlichen starken Oberflächenreflexion
detektieren zu können.Da systematische Fehler bei UWB Geräten technisch
nicht von vorne herein komplett vermeidbar sind, muss der Sensor eine
Gerätekalibrierung erlauben, um solche Fehler möglichst gut zu
unterdrĂĽcken.Aufgrund der genannten Anforderungen und den Nebenbedingungen
der Messumgebung unter Tage, wurde aus den verschiedenen UWB-Technologien
ein Prinzip ausgewählt, welches pseudozufällige Maximalfolgen als
Anregungssignal benutzt. Das M-Sequenzkonzept dient als Ausgangpunkt fĂĽr
zahlreiche Weiterentwicklungen. Ein neues Sendemodul erweitert dabei die
Messbandbreite auf 12~GHz. Die äquivalente Abtastrate wird um den Faktor
vier auf 36~GHz erhöht, ohne den geringen Abtastjitter des ursprünglichen
Konzepts zu vergrössern.Weiterhin wird die Umsetzung eines
Zweitormesskopfes zur Erfassung von S-Parametern sowie einer automatische
Kalibriereinheit beschrieben. Etablierte Kalibrierverfahren aus dem Bereich
der Netzwerkanalyse werden kurz rekapituliert und die Adaption des 8-Term
Verfahrens mit unbekanntem Transmissionsnormal fĂĽr das
M-Sequenzsystem beschrieben. Dabei werden Kennwerte vorgeschlagen, die dem
Bediener unter Tage einfach erlauben, die Kalibrierqualität einzuschätzen
und Hinweise auf mögliche Gerätefehler oder andere Probleme zu bekommen.
Die Kalibriergenauigkeit des neuen Sensors im Labor wird mit der eines
Netzwerkanalysators verglichen. Beide Geräte erreichen eine störungsfreie
Dynamik von mehr als 60~dB in den Systemimpulsantworten fĂĽr Reflexion und
Transmission.Der neu entwickelte UWB Sensor wurde in zahlreichen Messungen
in Salzminen in Deutschland getestet. Zwei Messbeispiele werden vorgestellt
- ein sehr alter, kreisrunder Tunnel sowie ein ovaler Tunnelstumpf,
welcher kurz vor den Messungen erst aufgefahren wurde. Messaufbauten und
Datenverarbeitung werden beschrieben. SchlieĂźlich werden Schlussfolgerungen
und Vorschläge für zukünftige Arbeiten mit dem neuen M-Sequenzsensor sowie
der Messung von Auflockerungen im Salzgestein diskutiert.This dissertation describes an innovative ultra-wideband
(UWB) electromagnetic sensor device based on a pseudo-noise principle
developed in the context of non-destructive testing in civil
engineering.Non-destructive testing is becoming a more and more important
fieldfor researchers and engineers alike. Besides the vast field of
possibleapplications and testing technologies, a prime and therefore
typical topic is the inspection and monitoringof constructions and
materials by means of contactless remote sensing techniques.This work
focuses on one example the assessment of the disaggregation zone in salt
rock tunnels.The background and relevance of knowing the state of salt rock
layers near a tunnel's surface are explainedand simple theoretical
considerations for requirements of suitable UWB sensor devices are shown.
The most important sensor parameters are a very large measurement bandwidth
and a very clean impulse response. The latterparameter translates into the
mandatory application of calibration techniques to remove systematic errors
of the sensor system itself. This enables detection of weak scattering
responses from near-surface disaggregation despite the presence of a strong
surface reflection.According to the mentioned requirements and other side
conditions in salt mine environments an UWB sensor principlebased on
pseudo-noise stimuli namely M-Sequences is selected as a starting point for
system development. A newtransmitter frontend for extending the stimulus
bandwidth up to 12~GHz is presented. Furthermore, a technique for
increasing the (equivalent) sampling rate while keeping the stable and
low-jitter sampling regime of the M-Sequencesapproach is introduced and its
implementation is shown. Moreover, an automatic calibration unit for full
two-port coaxial calibration of the new UWB sensor has been developed.
Common calibration techniques from the area of vector network analysers are
shortly reviewed and a reasonablealgorithm the 8-term method with an
unknown line standard - is selected for the M-Sequences device. The 8-term
method is defined in the frequency domain and is adapted for use with time
domain devices. Some performance figures and comparisonwith calibration
results from network analysers are discussed to show the effectiveness of
the calibration.A spurious-free dynamic range of the time domain impulse
responses in excess of 60~dB has been achieved for reflection as well as
transmission measurements.The new UWB sensor was used in various real world
measurements in different salt mines throughout Germany. Two
measurementexamples are described and results from the disaggregation zone
of a very old and a freshly cut tunnel will be presented. Measurement setup
and data processing are discussed and finally some conclusions for future
work on this topic are drawn
- …