A classification procedure for the effective management of changes during the maintenance process

During software operation, maintainers are often faced with numerous change requests. Given available resources such as effort and calendar time, changes, if approved, have to be planned to fit within budget and schedule constraints. In this paper, we address the issue of assessing the difficulty of a change based on known or predictable data. This paper should be considered as a first step towards the construction of customized economic models for maintainers. In it, we propose a modeling approach, based on regular statistical techniques, that can be used in a variety of software maintenance environments. The approach can be easily automated, and is simple for people with limited statistical experience to use. Moreover, it deals effectively with the uncertainty usually associated with both model inputs and outputs. The modeling approach is validated on a data set provided by NASA/GSFC which shows it was effective in classifying changes with respect to the effort involved in implementing them. Other advantages of the approach are discussed along with additional steps to improve the results

Nilpotent polynomials approach to four-qubit entanglement

We apply the general formalism of nilpotent polynomials [Mandilara et al, Phys. Rev. A 74, 022331 (2006)] to the problem of pure-state multipartite entanglement classification in four qubits. In addition to establishing contact with existing results, we explicitly show how the nilpotent formalism naturally suggests constructions of entanglement measures invariant under the required unitary or invertible class of local operations. A candidate measure of fourpartite entanglement is also suggested, and its behavior numerically tested on random pure states.Comment: 11 pages, 1 figure. Finalised versio

Telescope guide and pointing precision at THEMIS

We present the very basic features—from the observer’s point of view—of the software pack allowing for driving the telescope, the dome, the preslit at the primary focus and the field rotator between the primary and the secondary focus. The original program was developed by C. Veillet as an adaptation for THEMIS of the program used to drive the “Laser-Lune” telescope at the Observatoire of the Cˆote d’Azur (France). Further adaptations were made by the authors to meet observational and technical needs emerged during operation of the THEMIS telescope. When talking about the way observations at THEMIS are affected by the pointing precisionw e clearly have to distinguish betweento different levels: 1) a short-term effect, affecting short-term observing actions such as scans on the solar disk and 2) a long-term level affecting the correct tracking of a target. All short-term effects just depend on the precision of the software interface and we discuss here their origin, the way they are controlled, their value and how they affect scanning procedures. All long-term effects depend on precision of the software interface but also on mechanical and optical alignment accuracy

Multi-line spectro-polarimetry on active region NOAA 9125

We present here some preliminary results of observations performed with the spectro-polarimetric mode of the THEMIS telescope onactiv e regionNO AA 9125 on August 2000. We show the presence of high-velocity downflows located at the edge of a filament and stress on the non-stationary character of these flows. Flaring activities were also observed: we just present here some spectro-polarimetric profiles of these regions, more accurate magnetic-field configuration determination being performed latter on

Evaluating Model Testing and Model Checking for Finding Requirements Violations in Simulink Models

Matlab/Simulink is a development and simulation language that is widely used by the Cyber-Physical System (CPS) industry to model dynamical systems. There are two mainstream approaches to verify CPS Simulink models: model testing that attempts to identify failures in models by executing them for a number of sampled test inputs, and model checking that attempts to exhaustively check the correctness of models against some given formal properties. In this paper, we present an industrial Simulink model benchmark, provide a categorization of different model types in the benchmark, describe the recurring logical patterns in the model requirements, and discuss the results of applying model checking and model testing approaches to identify requirements violations in the benchmarked models. Based on the results, we discuss the strengths and weaknesses of model testing and model checking. Our results further suggest that model checking and model testing are complementary and by combining them, we can significantly enhance the capabilities of each of these approaches individually. We conclude by providing guidelines as to how the two approaches can be best applied together.Comment: 10 pages + 2 page reference

The cross-modal effects of packaging glossiness on haptic perception

International audienc

Inhibition of type III radio emissions due to the interaction between two electron beams: Observations and simulations

International audienceWe report the peculiar interaction of two type III bursts observed in the solar wind. As electronbeams propagating on the same magnetic field lines cross, a spectacular depletion of the type III radioemission is observed. We combine observations from the WAVES experiment on board the STEREO missiontogether with kinetic plasma simulations to study the extinction of type III radio emission resulting fromthe interaction between two electron beams. The remote observations enable to follow the electron beamsin the interplanetary medium and show that the level of radiated radio waves is recovered after the beamcrossing. The in situ observations of beam-driven Langmuir waves give evidence for Langmuir decay. Thedensity fluctuations are extracted from in situ observations. The velocity of the beams is independentlyevaluated from in situ observations of decaying Langmuir waves and remote radio observations. The kineticsimulations show that the level of beam-driven Langmuir waves is reduced as the two beams cross. Weshow that the slow beam induced a strong reduction of the quasilinear relaxation of the fast beam, limitingthe amplitude of the generated Langmuir waves. Moreover, in the case of two electron beams, the lack ofLangmuir wave coherence reduces the efficiency of the Langmuir parametric decay. We thus conclude thatthe observed depletion of the type III radio emission is independent of the radio emission mechanism, aslong as it depends on the Langmuir amplitude and coherence