1,174 research outputs found
Emergency locating transmitter
A transmitter generates three signals for sequential transmission. These signal are an unmodulated r.f. carrier, a r.f. carrier amplitude modulated by a first audio frequency waveform and a r.f. carrier amplitude modulated by a second audio frequency waveform which is distinguishable from the first and which may be employed as a means for identifying a particular transmitter. The composite, sequentially transmitted signal may be varied in terms of the individual signal transmission sequence, the duration of the individual signals, overall composite signal repetition rate and the frequency of the second audio waveform. Various combinations of signal variations may be employed to transmit different information
Method of and system for classifying emergency locating transmitters and emergency positions indicating radio beacons
During a distress call, a distress location transmitter 10 generates a high frequency carrier signal 40 that is modulated by a predetermined distress waveform characteristic 29. The classification of user associated with the distress call is identified by periodically interrupting modulation 42; user classification is determined by the repetition rate of the interruptions, the interruption periods, or both
Constraining The Small Binary Asteroid Population Of The Main Belt Using Doublet Craters On Ceres
Binary asteroids have been observed among the Near Earth Asteroids, among the Main Belt Asteroids, and even in the Trans-Neptunian Object population. Many were discovered by light curve analysis, some by direct or radar imaging, and a few by stellar occultation. Some were discovered using ground-based telescopes, and others by space-based assets such as the Hubble Space Telescope. As good as these instruments may be, no confirmed binary asteroids in the Main Belt have a primary body less than one kilometer in diameter.
The primary goal of this research was to confirm the existence of Main Belt binary asteroid systems with components smaller than one kilometer in diameter. Another goal of this research was to estimate a lower bound for the percentage of all Main Belt asteroids less than one kilometer in diameter that are binary systems. Doublet craters are believed to be caused by binary asteroid impacts, and their numbers can serve as a proxy for the number of binary asteroids among all impactors. Doublet craters were studied on the surface of Ceres using the latest detailed imagery returned by NASAâs Dawn spacecraft. A large sample area on the surface of Ceres was systematically surveyed to identify and locate all impact craters greater than a minimum diameter. All possible pairings were examined and evaluated for their potential as doublets, and the likely doublets allowed the percentage of impact events in the sample area that are created by binary asteroids to be determined. This percentage is proportional to the percentage of Main Belt asteroids that are themselves binary systems.
The sizes of impactors that created the observed impact craters were determined using a crater scaling law, providing conformation of small binary asteroid systems in the Main Belt
Emergency Locating Transmitter and Receiver System
A receiver and transmitter are provided for a distress incident locating telecommunications system. The receiver is a superheterodyne AM receiver which applies the received distress transmissions to a normally unlocked phaselock loop which locks onto the unmodulated carrier signal portion of the distress transmission. The duration of the phaselock loop being locked, and unlocked immediately after being locked, are measured and compared to predetermined values to find a match. Each of the predetermined values corresponds to an item of information, and if a match is found, the receiver indicates it. The receiver is also capable of extracting audio information present in the distress transmission. The transmitter generates three signals which can be applied to a transmitting antenna. These signals are a radio frequency carrier signal, and a carrier signal modulated by a distress waveform or by an audio signal. The signal which is ultimately applied to the transmitting antenna will have four parameters where each set of parameters corresponds to a different item of information. The parameters are which one or more of the three signals will be applied to the antenna, the sequence of application of the signals to the antenna, the duration of each of the signals, and the frequency of the audio signal
Capillary pumped loop body heat exchanger
A capillary pumped loop for transferring heat from one body part to another body part, the capillary pumped loop comprising a capillary evaporator for vaporizing a liquid refrigerant by absorbing heat from a warm body part, a condenser for turning a vaporized refrigerant into a liquid by transferring heat from the vaporized liquid to a cool body part, a first tube section connecting an output port of the capillary evaporator to an input of the condenser, and a second tube section connecting an output of the condenser to an input port of the capillary evaporator. A wick may be provided within the condenser. A pump may be provided between the second tube section and the input port of the capillary evaporator. Additionally, an esternal heat source or heat sink may be utilized
The Current State of Business Intelligence in Academia
Current trends suggest that academia may be behind the curve in delivering effective Business Intelligence programs and course offerings to students. In December 2009 and 2010, the AIS Special Interest Group on Decision Support, Knowledge and Data Management Systems (SIGDSS) and the Teradata University Network (TUN) cosponsored the Business Intelligence Congresses and conducted surveys to improve the understanding of the state of BI in academia. This panel report describes the key findings and best practices that were identified. The article also serves as a “call to action” for universities regarding the need to close a widening gap between the BI skills of university graduates in Information Systems and other fields and BI market needs. The IS field is well positioned to be the leader in creating the next generation BI workforce. To do so, it is important for IS to begin moving on this opportunity now. We believe the necessary first step is for BI and IS leaders to advance the BI curriculum
A Search for Early Optical Emission from Short and Long Duration Gamma-ray Bursts
Gamma-ray bursts of short duration may harbor vital clues to the range of
phenomena producing bursts. However, recent progress from the observation of
optical counterparts has not benefitted the study of short bursts. We have
searched for early optical emission from six gamma-ray bursts using the ROTSE-I
telephoto array. Three of these events were of short duration, including GRB
980527 which is among the brightest short bursts yet observed. The data consist
of unfiltered CCD optical images taken in response to BATSE triggers delivered
via the GCN. For the first time, we have analyzed the entire 16 degree by 16
degree field covered for five of these bursts. In addition, we discuss a search
for the optical counterpart to GRB 000201, a well-localized long burst. Single
image sensitivities range from 13th to 14th magnitude around 10 s after the
initial burst detection, and 14 - 15.8 one hour later. No new optical
counterparts were discovered in this analysis suggesting short burst optical
and gamma-ray fluxes are uncorrelated.Comment: 8 pages, 2 figures, subm. to ApJ Let
Prompt Optical Observations of Gamma-ray Bursts
The Robotic Optical Transient Search Experiment (ROTSE) seeks to measure
simultaneous and early afterglow optical emission from gamma-ray bursts (GRBs).
A search for optical counterparts to six GRBs with localization errors of 1
square degree or better produced no detections. The earliest limiting
sensitivity is m(ROTSE) > 13.1 at 10.85 seconds (5 second exposure) after the
gamma-ray rise, and the best limit is m(ROTSE) > 16.0 at 62 minutes (897 second
exposure). These are the most stringent limits obtained for GRB optical
counterpart brightness in the first hour after the burst. Consideration of the
gamma-ray fluence and peak flux for these bursts and for GRB990123 indicates
that there is not a strong positive correlation between optical flux and
gamma-ray emission.Comment: 4 pages, 3 figures, submitted to ApJ Letter
- …