573,249 research outputs found
A self-organising awareness system for distributed software engineering
Software engineers and other collaborative disciplines rely on informal "out-of-band" communication for ef-
fective coordination of their activities, especially in agile methods. This type of communication is lost when development is distributed, with consequent deleterious effects on engineer effectiveness. In order to effectively support distributed software engineering, a replacement for this informal communication must be found.
Much previous research focussed on either synchronous awareness such as radar views and shared editors, where participants were distributed in space not time, or asynchronous awareness such as change notification, which
did not explicitly support concurrent activities. A unified approach is necessary to support software engineering.
Furthermore, requiring co-location of engineering teams is not possible in today's marketplace where development
is often outsourced, consequently a definite requirement for awareness tools to replace informal communication
exists.
To implement an awareness tool capable of providing awareness of activities distributed both in time (asyn-
chronous awareness) and space (synchronous awareness). The tool will not rely on a centralised reflector; instead
information will be distributed over a peer-to-peer network arranged using a self-organisation algorithm.
Consequently awareness information need not travel more than a few hops from its originating peer, reducing
network load and increasing relevance of information received. Unlike reflector-based CSCW systems, the network
will scale and will not have a single point of failure in the reflector. Furthermore, without the need to setup a
reflector, there is the capability for ad-hoc awareness, using low-complexity peer discovery by local broadcast for
example.
The tool will be integrated with the Eclipse development environment. The files a user is currently editing will
determine the data they are interested in and fuzzy similarity metrics will be used to compare the collections of
each peer in the network in order to drive the self-organisation process. To evaluate the success of self-organisation,
a simulation approach will be used before deploying the algorithms in the wild. To evaluate the effectiveness of
the awareness provision, initial deployment and controlled experiments will be conducted within the Distributed
Software Engineering group at the University of Lincoln and a later version of the tool will be trialled with existing
Eclipse user
UAV as a Reliable Wingman: A Flight Demonstration
In this brief, we present the results from a flight experiment demonstrating two significant advances in software enabled control: optimization-based control using real-time trajectory generation and logical programming environments for formal analysis of control software. Our demonstration platform consisted of a human-piloted F-15 jet flying together with an autonomous T-33 jet. We describe the behavior of the system in two scenarios. In the first, nominal state communications were present and the autonomous aircraft maintained formation as the human pilot flew maneuvers. In the second, we imposed the loss of high-rate communications and demonstrated an autonomous safe “lost wingman” procedure to increase separation and reacquire contact. The flight demonstration included both a nominal formation flight component and an execution of the lost wingman scenario
Optimization of star research algorithm for esmo star tracker
This paper explains in detail the design and the development of a software research star algorithm, embedded on a star tracker, by the ISAE/SUPAERO team. This research algorithm is inspired by musical techniques. This work will be carried out as part of the ESMO (European Student Moon Orbiter) project by different teams of students and professors from ISAE/SUPAERO (Institut Supe ́rieur de l’Ae ́ronautique et de l’Espace). Till today, the system engineering studies have been completed and the work that will be presented will concern the algorithmic and the embedded software development. The physical architecture of the sensor relies on APS 750 developed by the CIMI laboratory of ISAE/SUPAERO. First, a star research algorithm based on the image acquired in lost-in-space mode (one of the star tracker opera- tional modes) will be presented; it is inspired by techniques of musical recognition with the help of the correlation of digital signature (hash) with those stored in databases. The musical recognition principle is based on finger- printing, i.e. the extraction of points of interest in the studied signal. In the musical context, the signal spectrogram is used to identify these points. Applying this technique in image processing domain requires an equivalent tool to spectrogram. Those points of interest create a hash and are used to efficiently search within the database pre- viously sorted in order to be compared. The main goals of this research algorithm are to minimise the number of steps in the computations in order to deliver information at a higher frequency and to increase the computation robustness against the different possible disturbances
Implicit Measures of Lostness and Success in Web Navigation
In two studies, we investigated the ability of a variety of structural and temporal measures computed from a web navigation path to predict lostness and task success. The user’s task was to find requested target information on specified websites. The web navigation measures were based on counts of visits to web pages and other statistical properties of the web usage graph (such as compactness, stratum, and similarity to the optimal path). Subjective lostness was best predicted by similarity to the optimal path and time on task. The best overall predictor of success on individual tasks was similarity to the optimal path, but other predictors were sometimes superior depending on the particular web navigation task. These measures can be used to diagnose user navigational problems and to help identify problems in website design
Towards Efficient Detection of Small Near-Earth Asteroids Using the Zwicky Transient Facility (ZTF)
We describe ZStreak, a semi-real-time pipeline specialized in detecting
small, fast-moving near-Earth asteroids (NEAs) that is currently operating on
the data from the newly-commissioned Zwicky Transient Facility (ZTF) survey.
Based on a prototype originally developed by Waszczak et al. (2017) for the
Palomar Transient Factory (PTF), the predecessor of ZTF, ZStreak features an
improved machine-learning model that can cope with the data rate
increment between PTF and ZTF. Since its first discovery on 2018 February 5
(2018 CL), ZTF/ZStreak has discovered confirmed new NEAs over a total of
232 observable nights until 2018 December 31. Most of the discoveries are small
NEAs, with diameters less than m. By analyzing the discovery
circumstances, we find that objects having the first to last detection time
interval under 2 hr are at risk of being lost. We will further improve
real-time follow-up capabilities, and work on suppressing false positives using
deep learning.Comment: PASP in pres
UVUDF: Ultraviolet Imaging of the Hubble Ultradeep Field with Wide-field Camera 3
We present an overview of a 90-orbit Hubble Space Telescope treasury program
to obtain near ultraviolet imaging of the Hubble Ultra Deep Field using the
Wide Field Camera 3 UVIS detector with the F225W, F275W, and F336W filters.
This survey is designed to: (i) Investigate the episode of peak star formation
activity in galaxies at 1<z<2.5; (ii) Probe the evolution of massive galaxies
by resolving sub-galactic units (clumps); (iii) Examine the escape fraction of
ionizing radiation from galaxies at z~2-3; (iv) Greatly improve the reliability
of photometric redshift estimates; and (v) Measure the star formation rate
efficiency of neutral atomic-dominated hydrogen gas at z~1-3. In this overview
paper, we describe the survey details and data reduction challenges, including
both the necessity of specialized calibrations and the effects of charge
transfer inefficiency. We provide a stark demonstration of the effects of
charge transfer inefficiency on resultant data products, which when
uncorrected, result in uncertain photometry, elongation of morphology in the
readout direction, and loss of faint sources far from the readout. We agree
with the STScI recommendation that future UVIS observations that require very
sensitive measurements use the instrument's capability to add background light
through a "post-flash". Preliminary results on number counts of UV-selected
galaxies and morphology of galaxies at z~1 are presented. We find that the
number density of UV dropouts at redshifts 1.7, 2.1, and 2.7 is largely
consistent with the number predicted by published luminosity functions. We also
confirm that the image mosaics have sufficient sensitivity and resolution to
support the analysis of the evolution of star-forming clumps, reaching 28-29th
magnitude depth at 5 sigma in a 0.2 arcsecond radius aperture depending on
filter and observing epoch.Comment: Accepted A
Astrometry.net: Blind astrometric calibration of arbitrary astronomical images
We have built a reliable and robust system that takes as input an
astronomical image, and returns as output the pointing, scale, and orientation
of that image (the astrometric calibration or WCS information). The system
requires no first guess, and works with the information in the image pixels
alone; that is, the problem is a generalization of the "lost in space" problem
in which nothing--not even the image scale--is known. After robust source
detection is performed in the input image, asterisms (sets of four or five
stars) are geometrically hashed and compared to pre-indexed hashes to generate
hypotheses about the astrometric calibration. A hypothesis is only accepted as
true if it passes a Bayesian decision theory test against a background
hypothesis. With indices built from the USNO-B Catalog and designed for
uniformity of coverage and redundancy, the success rate is 99.9% for
contemporary near-ultraviolet and visual imaging survey data, with no false
positives. The failure rate is consistent with the incompleteness of the USNO-B
Catalog; augmentation with indices built from the 2MASS Catalog brings the
completeness to 100% with no false positives. We are using this system to
generate consistent and standards-compliant meta-data for digital and digitized
imaging from plate repositories, automated observatories, individual scientific
investigators, and hobbyists. This is the first step in a program of making it
possible to trust calibration meta-data for astronomical data of arbitrary
provenance.Comment: submitted to A
Symbolic Partial-Order Execution for Testing Multi-Threaded Programs
We describe a technique for systematic testing of multi-threaded programs. We
combine Quasi-Optimal Partial-Order Reduction, a state-of-the-art technique
that tackles path explosion due to interleaving non-determinism, with symbolic
execution to handle data non-determinism. Our technique iteratively and
exhaustively finds all executions of the program. It represents program
executions using partial orders and finds the next execution using an
underlying unfolding semantics. We avoid the exploration of redundant program
traces using cutoff events. We implemented our technique as an extension of
KLEE and evaluated it on a set of large multi-threaded C programs. Our
experiments found several previously undiscovered bugs and undefined behaviors
in memcached and GNU sort, showing that the new method is capable of finding
bugs in industrial-size benchmarks.Comment: Extended version of a paper presented at CAV'2
Log-based Anomaly Detection of CPS Using a Statistical Method
Detecting anomalies of a cyber physical system (CPS), which is a complex
system consisting of both physical and software parts, is important because a
CPS often operates autonomously in an unpredictable environment. However,
because of the ever-changing nature and lack of a precise model for a CPS,
detecting anomalies is still a challenging task. To address this problem, we
propose applying an outlier detection method to a CPS log. By using a log
obtained from an actual aquarium management system, we evaluated the
effectiveness of our proposed method by analyzing outliers that it detected. By
investigating the outliers with the developer of the system, we confirmed that
some outliers indicate actual faults in the system. For example, our method
detected failures of mutual exclusion in the control system that were unknown
to the developer. Our method also detected transient losses of functionalities
and unexpected reboots. On the other hand, our method did not detect anomalies
that were too many and similar. In addition, our method reported rare but
unproblematic concurrent combinations of operations as anomalies. Thus, our
approach is effective at finding anomalies, but there is still room for
improvement
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