66,765 research outputs found
Characterizing the strongly jump-traceable sets via randomness
We show that if a set is computable from every superlow 1-random set,
then is strongly jump-traceable. This theorem shows that the computably
enumerable (c.e.) strongly jump-traceable sets are exactly the c.e.\ sets
computable from every superlow 1-random set.
We also prove the analogous result for superhighness: a c.e.\ set is strongly
jump-traceable if and only if it is computable from every superhigh 1-random
set.
Finally, we show that for each cost function with the limit condition
there is a 1-random set such that every c.e.\ set
obeys . To do so, we connect cost function strength and the strength of
randomness notions. This result gives a full correspondence between obedience
of cost functions and being computable from 1-random sets.Comment: 41 page
Integrating nuclide specific and dose rate based methods for airborne and ground based gamma spectrometry
Results of joint airborne survey work conducted by SUERC and JAEA are presented, for areas to the north and south of Fukushima Daiichi using four different airborne survey systems, cross calibrated at reference sites in Scotland and near Namie. Airborne measurements were made at a series of different survey heights using three high volume NaI based spectrometers, and for the first time using a high resolution system based on the Ortec IDM HPGe spectrometer. The JAEA data sets were analysed using the same methods applied to national scale mapping in Japan since the accident. The SUERC data sets were analysed using nuclide specific approaches validated in the European ECCOMAGS project. The data presented on a digital terrain model show marked correspondence with landscape features, which both suggest the initial deposition processes, and indicate trajectories for future re-deposition by natural processes. All data sets are traceable to each other, and to the ground based calibration sites. Nuclide specific inventories have been defined, which can serve as a future reference to evaluate environmental change
CERTIFICATION REPORT: The certification of the absorbed energy (120 J nominal) of Charpy V-notch reference test pieces for tests at 20 °C: ERM®-FA016bh
This certification report describes the processing and characterisation of ERM®-FA016bh, a batch of Charpy V-notch reference test pieces certified for the absorbed energy (KV). Sets of five of these test pieces are used for the verification of pendulum impact test machines according to ISO 148-2 (Metallic materials - Charpy pendulum impact test – Part 2: Verification of testing machines).
The absorbed energy (KV) is operationally defined and refers to the impact energy required to break a V-notched test piece of standardised dimensions, as defined in ISO 148-1. The certified value of ERM®-FA016bh is made traceable to the SI, via the SI-traceable certified value of the master batch ERM®-FA016ax, by testing samples of ERM®-FA016bh and ERM®-FA016ax under repeatability conditions on an impact pendulum verified and calibrated with SI-traceable tools. The certified value is valid only for strikers with a 2 mm tip radius and at (20 ± 2) °C.JRC.F.6-Reference Material
Bounded Concurrent Timestamp Systems Using Vector Clocks
Shared registers are basic objects used as communication mediums in
asynchronous concurrent computation. A concurrent timestamp system is a higher
typed communication object, and has been shown to be a powerful tool to solve
many concurrency control problems. It has turned out to be possible to
construct such higher typed objects from primitive lower typed ones. The next
step is to find efficient constructions. We propose a very efficient wait-free
construction of bounded concurrent timestamp systems from 1-writer multireader
registers. This finalizes, corrects, and extends, a preliminary bounded
multiwriter construction proposed by the second author in 1986. That work
partially initiated the current interest in wait-free concurrent objects, and
introduced a notion of discrete vector clocks in distributed algorithms.Comment: LaTeX source, 35 pages; To apper in: J. Assoc. Comp. Mac
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