37,452 research outputs found
Enhanced sharing analysis techniques: a comprehensive evaluation
Sharing, an abstract domain developed by D. Jacobs and A. Langen for the analysis of logic
programs, derives useful aliasing information. It is well-known that a commonly used core
of techniques, such as the integration of Sharing with freeness and linearity information, can
significantly improve the precision of the analysis. However, a number of other proposals for
refined domain combinations have been circulating for years. One feature that is common
to these proposals is that they do not seem to have undergone a thorough experimental
evaluation even with respect to the expected precision gains.
In this paper we experimentally
evaluate: helping Sharing with the definitely ground variables found using Pos, the domain
of positive Boolean formulas; the incorporation of explicit structural information; a full
implementation of the reduced product of Sharing and Pos; the issue of reordering the
bindings in the computation of the abstract mgu; an original proposal for the addition of
a new mode recording the set of variables that are deemed to be ground or free; a refined
way of using linearity to improve the analysis; the recovery of hidden information in the
combination of Sharing with freeness information. Finally, we discuss the issue of whether
tracking compoundness allows the computation of more sharing information
Readout Electronics Tests and Integration of the ATLAS Semiconductor Tracker
The SemiConductor Tracker (SCT) together with the Pixel detector and the
Transition Radiation Tracker (TRT) form the central tracking system of the
ATLAS experiment at the LHC. It consists of single-sided microstrip silicon
sensors, which are read out via binary ASICs based on the DMILL technology, and
the data are transmitted via radiation-hard optical fibres. After an overview
of the SCT detector layout and readout system, the final-stage assembly of
large-scale structures and the integration with the TRT is presented. The focus
is on the electrical performance of the overall SCT detector system through the
different integration stages, including the detector control and data
acquisition system.Comment: 5 pages, 12 figures, Contributed to 12th Workshop On Electronics For
LHC And Future Experiments (LECC 2006), 25-29 September 2006, Valencia, Spai
The Outer Tracker Detector of the HERA-B Experiment. Part II: Front-End Electronics
The HERA-B Outer Tracker is a large detector with 112674 drift chamber
channels. It is exposed to a particle flux of up to 2x10^5/cm^2/s thus coping
with conditions similar to those expected for the LHC experiments. The
front-end readout system, based on the ASD-8 chip and a customized TDC chip, is
designed to fulfil the requirements on low noise, high sensitivity, rate
tolerance, and high integration density. The TDC system is based on an ASIC
which digitizes the time in bins of about 0.5 ns within a total of 256 bins.
The chip also comprises a pipeline to store data from 128 events which is
required for a deadtime-free trigger and data acquisition system. We report on
the development, installation, and commissioning of the front-end electronics,
including the grounding and noise suppression schemes, and discuss its
performance in the HERA-B experiment
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Creating awareness of kinaesthetic learning using the Experience API: current practices, emerging challenges, possible solutions
We describe our use of the Experience API in preparing blue-collar workers for three frequently arising work contexts, including, for example, the requirement to perform maintenance tasks exactly as specified, consistently, quickly, and without error. We provide some theoretical underpinning for modifying and updating the API to remain useful in near-future training scenarios, such as having a shorter time allowed for kinaesthetic learning experiences than in traditional apprenticeships or training. We propose ways to involve a wide range of stakeholders in appraising the API and ensuring that any enhancements to it, or add-ons, are useful, feasible and compatible with current TEL practices and tools, such as learning-design modelling languages
A Student Spacecraft for In-Orbit Test of NASA Tracking Programs
The spacecraft SURFSAT-1, now being designed, built, tested, and integrated by undergraduate college students, is to be launched as a secondary payload on a NASA rocket in the spring of 1995. The spacecraft consists of two boxes, roughly 12 x 12 x 16 , mounted permanently to the avionics bay structure of the second stage of a Delta II launch vehicle which will carry the Canadian RADARSAT Base. The boxes are powered by their own solar cells with no electrical connection to the second stage structure other then grounding. When in orbit the spacecraft, which will cost less than $2.5M, including test and launch integration, will be used routinely for several years as a test vehicle for NASA. The spacecraft will carry low-power radio transmitters which radiate milliwatts of power in three microwave bands to NASA tracking stations for deep space communication R&D, for testing a new set of earth orbiter tracking stations, and for training tracking station operators
Visual Reference and Iconic Content
Evidence from cognitive science supports the claim that humans and other animals see the world as divided into objects. Although this claim is widely accepted, it remains unclear whether the mechanisms of visual reference have representational content or are directly instantiated in the functional architecture. I put forward a version of the former approach that construes object files as icons for objects. This view is consistent with the evidence that motivates the architectural account, can respond to the key arguments against representational accounts, and has explanatory advantages. I draw general lessons for the philosophy of perception and the naturalization of intentionality
Grounding the Lexical Semantics of Verbs in Visual Perception using Force Dynamics and Event Logic
This paper presents an implemented system for recognizing the occurrence of
events described by simple spatial-motion verbs in short image sequences. The
semantics of these verbs is specified with event-logic expressions that
describe changes in the state of force-dynamic relations between the
participants of the event. An efficient finite representation is introduced for
the infinite sets of intervals that occur when describing liquid and
semi-liquid events. Additionally, an efficient procedure using this
representation is presented for inferring occurrences of compound events,
described with event-logic expressions, from occurrences of primitive events.
Using force dynamics and event logic to specify the lexical semantics of events
allows the system to be more robust than prior systems based on motion profile
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