71 research outputs found
Editorial of the Special Issue "Selected Papers from TimeNav 2007: Frequency-Time-Navigation EFTF, IEEE-FCS, ENC-GNSS: A selection of Papers"
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First evaluation and experimental results on the determination of uncertainties in [UTC – UTC (k)]
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Application of Millisecond Pulsar Timing to the Long-Term Stability of Clock Ensembles
No full textTerrestrial timescales show instabilities due to the physical limitations of the atomic clocks. Stricter environmental isolation and increased numbers of improved cesium clocks and cavity-tuned hydrogen masers have resulted in time scales more accurate by a factor of about five. The use of different clock ensembles results in measurable changes in some millisecond pulsar timing data. We investigate the possible application of millisecond pulsars to define a precise long-term time standard and positional reference system in a nearly inertial reference frame. Although possible quantitative contribution of the two longest studied millisecond pulsars to terrestrial timescales appears minimal, they may prove useful as independent standards in identifying error sources that are difficult to detect due to the finite lifetime and common reference frame of terrestrial clocks. New millisecond pulsars, perhaps some with even better timing properties, may be discovered as a result of the current g..
Measurements of irregularities in the mid‐latitude ionosphere with a radio interferometer
No full textA time-aware type system for data-race protection and guaranteed initialization
No full textWe introduce a type system based on intervals, objects representing the time in which a block of code will execute. The type system can verify time-based properties such as when a field will be accessed or a method will be invoked.
One concrete application of our type system is data-race protection: For fields which are initialized during one phase of the program and constant thereafter, users can designate the interval during which the field is mutable. Code which happens after this initialization interval can safely read the field in parallel. We also support fields guarded by a lock and even the use of dynamic race detectors.
Another use for intervals is to designate different phases in the object's lifetime, such as a constructor phase. The type system then ensures that only appropriate methods are invoked in each phase.</jats:p
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