Voltage controlled metamaterial

International audienceA tunable metamaterial based on conducting coils loaded by an electronic circuit containing a varicap diode has been demonstrated. The agility exceeds one octave inside the 100-500 MHz range. Permeability levels are significantly increased when the loop is loaded by a proper magnetic material. A model gives a good desription of the observed permeability spectra

Microwave properties of diluted composites made of magnetic wires with giant magneto impedance effect

International audienceIn this paper, the theoretical description of wire media made of magnetic wires. We show that there is a close link between the Giant Magneto Impedence effect (GMI) in individual wires, and free-space microwave properties of the composite wire media. The demonstration with tunable dielectric constant under a static magnetic field

Effect of the magnetic properties of the inclusions on the high-frequency dielectric response of diluted composites

International audienceThe high-frequency permittivity of composites consisting of a lattice of ferromagnetic wires is investigated. Experimental results using free space or coaxial line microwave measurements are reported. It is shown that the dielectric response is strongly dependent on the magnetic properties of the wires. Negative real permittivity is observed over a wide frequency range for wires with circumferential magnetization, while a resonant behavior is observed on wires with an axially magnetized core. In addition, it is shown that a moderate external field can induce large changes in the dielectric response. We prove that the underlying physics of these composites made of oriented magnetic wires is basically the same as the giant magnetoimpedance (GMI) effect. A model based on GMI equations is proposed which predicts this unusual dielectric phenomenon

Desktop cutting of paper using a single emitter laser diode and inkjet printing

International audienceLaser cutting of paper is widely used in the paper conversion industry. CO 2 lasers are well suited for this type of applications. Desktop printing is a large market both for digital photography, document management and graphics applications, but it still lacks advanced cutting and scoring ability, and CO 2 lasers seem costly to be integrated in mass-market printers. For that reason, mass-scalable and low-cost semiconductor laser diodes would be very advantageous to add paper cutting and scoring features in desktop printers. However, common paper can not be cut properly using visible or Near Infrared (NIR) laser diode since it has a very poor absorption at these wavelengths. We report here an innovative solution to achieve paper cutting or scoring using a 1 W single emitter NIR laser diode, within an inkjet printer. A special ink that absorbs the NIR light, and that penetrates all through the paper, is first disposed on the lines to be cut. Then, the laser diode goes along the lines to be cut. We show that a cutting speed of 2m/min can be achieved on 80g/m 2 conventional paper. The influence of the optical properties of the ink on the cutting speed are discussed, as well as focussing issues. In particular, we show that invisible inks are suitable, and very clear-cut edges can be obtained. The perspective of this technique are discussed

Generating Counterexamples of Model-based Software Product Lines: An Exploratory Study

International audienceModel-based Software Product Line (MSPL) engineering ai- ms at deriving customized models corresponding to individ- ual products of a family. MSPL approaches usually promote the joint use of a variability model, a base model expressed in a specific formalism, and a realization layer that maps variation points to model elements. The design space of an MSPL is extremely complex to manage for the engineer, since the number of variants may be exponential and the derived product models have to be conformant to numerous well-formedness and business rules. In this paper, the objec- tive is to provide a way to generate MSPLs, called counterex- amples, that can produce invalid product models despite a valid configuration in the variability model. We provide a systematic and automated process, based on the Common Variability Language (CVL), to randomly search the space of MSPLs for a specific formalism. We validate the effective- ness of this process for three formalisms at different scales (up to 247 metaclasses and 684 rules). We also explore and discuss how counterexamples could guide practitioners when customizing derivation engines, when implementing check- ing rules that prevent early incorrect CVL models, or simply when specifying an MSPL

Characterization of Angle Accuracy and Precision of 3-Degree-of-Freedom Absolute Encoder Based on NanoGPS OxyO Technology

An absolute encoder based on vision system nanoGPS OxyO was developed by HORIBA France. This encoder provides three types of position information, namely, two inplane co-ordinates and inplane angular orientation. This paper focuses on the characterization of its angular performance. To this aim, the nanoGPS OxyO system was compared with the national angle standard of the National Metrology Institute of Italy (INRIM) that had evaluated accuracy of about 0.1 urad. The effect of image size and illumination conditions on angular measurements was studied. Precision better than 10 urad and accuracy better than 63 urad over 2π rotation were demonstrated. Moreover, the application of nanoGPS OxyO to the characterization of rotation bearing is presented. Small deviations from pure rotational behavior were evidenced that would have not been possible using laser interferometers. As a consequence of its accuracy and versatility, the nanoGPS OxyO encoder is expected to be useful for laboratory experiments and quality-control tasks

Preprocessing is What You Need: Understanding and Predicting the Complexity of SAT-based Uniform Random Sampling

peer reviewedDespite its NP-completeness, the Boolean satisfiability problem gave birth to highly efficient tools that are able to find solutions to a Boolean formula and compute their number. Boolean formulae compactly encode huge, constrained search spaces for variability-intensive systems, e.g., the possible configurations of the Linux kernel. These search spaces are generally too big to explore exhaustively, leading most testing approaches to sample a few solutions before analysing them. A desirable property of such samples is uniformity: each solution should get the same selection probability. This property motivated the design of uniform random samplers, relying on SAT solvers and counters and achieving different tradeoffs between uniformity and scalability. Though we can observe their performance in practice, understanding the complexity these tools face and accurately predicting it is an under-explored problem. Indeed, structural metrics such as the number of variables and clauses involved in a formula poorly predict the sampling complexity. More elaborated ones, such as minimal independent support (MIS), are intractable to compute on large formulae. We provide an efficient parallel algorithm to compute a related metric, the number of equivalence classes, and demonstrate that this metric is highly correlated to time and memory usage of uniform random sampling and model counting tools. We explore the role of formula preprocessing on various metrics and show its positive influence on correlations. Relying on these correlations, we train an efficient classifier (F1-score 0.97) to predict whether uniformly sampling a given formula will exceed a specified budget. Our results allow us to characterise the similarities and differences between (uniform) sampling, solving and counting. c 202

Customization and 3D Printing: A Challenging Playground for Software Product Lines

International audience3D printing is gaining more and more momentum to build customized product in a wide variety of fields. We conduct an exploratory study of Thingiverse, the most popular Website for sharing user-created 3D design files, in order to establish a possible connection with software product line (SPL) engineering. We report on the socio-technical aspects and current practices for modeling variability, implementing variability, configuring and deriving products, and reusing artefacts. We provide hints that SPL-alike techniques are practically used in 3D printing and thus relevant. Finally, we discuss why the customization in the 3D printing field represents a challenging playground for SPL engineering

Software Diversity: Challenges to handle the imposed, Opportunities to harness the chosen

National audienceDiversity emerges as a critical concern that spans all activities in software engineering (from design to verification, from deployment to runtime resilience) and appears in all sorts of domains, which rely on software intensive systems, from systems of systems to pervasive combinations of Internet of Things and Internet of Services. If these domains are apparently radically different, we envision a strong convergence of the scientific principles underpinning their construction and validation towards flexible and open yet dependable systems. In this paper, we discuss the software engineering challenges raised by these requirements for flexibility and openness, focusing on four dimensions of diversity: the diversity of functionalities required by the different customers; the diversity of languages used by the stakeholders involved in the construction of these systems; the diversity of runtime environments in which software has to run and adapt; the diversity of failures against which the system must be able to react. In particular, we want to emphasize the challenges for handling imposed diversity, as well as the opportunities to leverage chosen diversity. The main challenge is that software diversity imposes to integrate the fact that software must adapt to changes in the requirements and environment -- in all development phases and in unpredictable ways. Yet, exploiting and increasing software diversity is a great opportunity to allow the spontaneous exploration of alternative software solutions and proactively prepare for unforeseen changes. Concretely, we want to provide software engineers with the ability: to characterize an 'envelope' of possible variations; to compose 'envelopes' (to discover new macro envelopes in an opportunistic manner); to dynamically synthesize software inside a given envelop