A Graph Transformation Approach for Modeling and Verification of UML 2.0 Sequence Diagrams

Unified Modeling Language (UML) 2.0 Sequence Diagrams (UML 2.0 SD) are used to describe interactions in software systems. These diagrams must be verified in the early stages of software development process to guarantee the production of a reliable system. However, UML 2.0 SD lack formal semantics as all UML specifications, which makes their verification difficult, especially if we are modeling a critical system where the automation of verification is necessary. Communicating Sequential Processes (CSP) is a formal specification language that is suited for analysis and has many automatic verification tools. Thus, UML and CSP have complementary aspects, which are modeling and analysis. Recently, a formalization of UML 2.0 SD using CSP has been proposed in the literature; however, no automation of that formalization exists. In this paper, we propose an approach on the basis of the above formalization and a visual modeling tool to model and automatically transform UML 2.0 SD to CSP ones; thus, the existing CSP model checker can verify them. This approach aims to use UML 2.0 SD for modeling and CSP and its tools for verification. This approach is based on graph transformation, which uses AToM3 tool and proposes a metamodel of UML 2.0 SD and a graph grammar to perform the mapping of the latter into CSP. Failures-Divergence Refinement (FDR) is the model checking tool used to verify the behavioral properties of the source model transformation such as deadlock, livelock and determinism. The proposed approach and tool are illustrated through a case study

Experimental Study And Modeling Of Water Retention Curve Of A Silty Soil Compacted And Treated With Cement

The evaluation of unsaturated soils' fundamental properties is ensured by the characteristic water retention curve for a wide range of soil suction values. However, a minimal number of research works have focused on studying the water retention properties of natural soils and treated with hydraulic binders using soil-water characteristic curves (SWCC). The present work is motivated by the lack of experimental evidence of this type. Firstly, experimental measurements of soil-water characteristic curves of a natural loam soil from the region of Sidi Bel Abbes (Algeria), treated with cement and compacted at Standard Optimum Proctor at an ambient temperature of 20 °C, Were carried out using the methods of the imposition of suction, namely the osmotic method ranging from 0 to 0.05 MPa and the method of saline solutions over a suction range from 0.05 MPa to about 343 MPa respectively. The suction used were applied to four studied mixtures (natural soil, + 2%, + 4% and + 6% cement). At the end of the tests on the drainage-humidification path, the water retention curves for the treated soil at different cement dosage allow us to determine the different state parameters of the treated soil: Degree of saturation (Sr), dry weight (d), void ratio (e) and water content (w). The suction imposition range and the cement dosage significantly influence the water behavior of the material studied. On the other hand, we develop a model of the water behavior of soils treated with cement. This model makes it possible to correctly predict the retention curves at different cement dosage from the experimental measurements performed on samples compacted at Standard Optimum Proctor represented in the plans [suction, degree of saturation] and [suction, moisture content]

Forward Modeling of Transducer Misalignment Effects in Ultrasonic Leaky Wave Measurements

Ultrasonic measurements performed with a pair of acoustic transducers in pitch-catch mode are of common use in the NDE field. In particular, for nearfield leaky wave (LW) measurements which are directed at precise determination of material properties of layered elastic structure in immersion. In LW measurements, the acoustic transducer beams are aligned at angles so as to phase match to one or several of the structure’s leaky (Rayleigh or Lamb) waves. The amplitude and phase of the scattered acoustic energy collected, and converted to an electrical voltage, by the phase-sensitive receiving transducer depends not only on the properties of the structure but also on the parameters of the transducers used, in particular, their apertures and alignment angles. Transducer alignment issues are especially important for transducers that radiate or receive over a narrow angular range

Guided Waves in Fluid-Elastic Concentric and Non-Concentric Cylindrical Structures: Theoretical and Experimental Investigations

Modeling and understanding the complex elastic-wave physics prevalent in fluid-elastic cylindrically-layered structures is of importance in many NDE fields, and most pertinently in the domain of well integrity evaluation in the oil and gas industry. It is believed that acoustical measurements provide one of the effective means to provide a diagnosis. Historically, the problem has been researched and addressed to a good extent for well intervals with a single steel string. For these cases, high-frequency ultrasonic imaging has been optimized and demonstrated to yield acceptable diagnosis of the annulus properties behind the first string the signal encounters. However, they fail to provide information about the outer annulus in a double or triple string geometry. To probe with more effective radial depth, lower-frequency signals are used. In a typical double-string configuration, the inner casing is eccentered with respect to the outer string which itself is also eccentered within the cylindrical hole. The annuli may or may not be filled with solid cement, and the cement may have liquid-filled channels or be disbonded over localized azimuthal ranges. The complexity of wave propagation along axial intervals is significant in that multiple modes can be excited and detected with characteristics that are affected by the various parameters in a non-linear fashion. To gain understanding of the complex wave physics and leverage it to design effective diagnosis means, we have developed modeling capabilities that address the configurations of interest. In this talk, we first establish a mathematical framework to analyze the guided wave fields in a multi-string system embedded in infinite media. We then develop and implement a Chirp Sweeping Finite Element Modeling (CSFEM) method to investigate the dispersions and modal characteristics of the complex propagating signals synthesized over an axial array of receivers. The CSFEM provides for a flexible framework to study the modal sensitivities in a multi-string system with arbitrary eccentricity, azimuthal heterogeneities, and partial bonded interfaces. We have also conducted scaled laboratory experiments to acquire reference data used to verify the range of validity of the modeling approach in predicting the guided modal characteristics of axially-propagating waves in concentric and non-concentric cylindrical structures immersed in fluid. An acoustic transmitter having four selectable, active elements at 90 degrees apart allows sourcing of all guided modes of interest and is located at one end of the string length. Received waveforms are acquired from a single receiver which is scanned axially and circumferentially inside the inner string. The acquired data set is then analyzed for spectral modal content using both Slowness-Time-Coherence and Matrix Pencil methods and compared to theoretical predictions. The comparisons indicate good agreement and provide confidence in the CSFEM capability to accurately predict the complex wave field dispersion characteristics estimated from the experimentally acquired signals in the fluid-filled double string geometries

Une approche multi-agent pour la segmentation d'images de profondeur

National audienceDans cet article, nous présentons et nous évaluons une approche multi-agent pour la segmentation d’images de profondeur. L’approche consiste en l’utilisation d’une population d’agents autonomes pour la segmentation d’une image de profondeur en ses différentes régions planes. Les agents s’adaptent aux régions sur lesquelles ils se déplacent, puis effectuent des actions coopératives et compétitives produisant une segmentation collective de l’image. Un champ de potentiel artificiel est introduit afin de coordonner les mouvements des agents et de leur permettre de s’organiser autour des pixels d’intérêt. Les résultats expérimentaux obtenus par des images réelles montrent le potentiel de l’approche proposée pour l’analyse des images de profondeurs, et ce vis-à-vis de l’efficacité de segmentation et de la fiabilité des résultats

Time-averaged second-order pressure and velocity measurements in a pressurized oscillating flow prime mover

Nonlinear phenomena in oscillating flow devices cause the appearance of a relatively minor secondary flow known as acoustic streaming, which is superimposed on the primary oscillating flow. Knowledge of control parameters, such as the time-averaged second-order velocity and pressure, would elucidate the non-linear phenomena responsible for this part of the decrease in the system’s energetic efficiency. This paper focuses on the characterization of a travelling wave oscillating flow engine by measuring the time-averaged secondorder pressure and velocity. Laser Doppler velocimetry technique was used to measure the time-averaged second-order velocity. As streaming is a second-order phenomenon, its measurement requires specific settings especially in a pressurized device. Difficulties in obtaining the proper settings are highlighted in this study. The experiments were performed for mean pressures varying from 10 bars to 22 bars. Non-linear effect does not constantly increase with pressure

Controlled release from polyurethane films: Drug release mechanisms

In this study, polyurethane-films loaded with diclofenac were used to analyze the drug release kinetics and mechanisms. For this purpose, the experimental procedures were developed under static and dynamic conditions with different initial drug loads of 10, 20, and 30%. In the dynamic condition, to better simulate the biological flow, drug release measurements were investigated at flow rates of 7.5 and 23.5 ml/s. These values indicate the flow rate of the internal carotid artery (ICA) for a normal state of a body and for a person during the exercise, respectively. The experimental data were analyzed and adjusted by Higuchi, Korsmeyer–Peppas, First-order, zero-order, and Peppas–Sahlin models in order to understand the mechanisms contributed. Finally, drug release mechanisms were specified by investigating the model correlation coefficients. Experimental results showed that increasing the flow rate and initial drug loads enhance drug liberation. In addition, the rate of release is more influenced by the drug dosage in the static state. The analysis revealed that diffusion, burst, and osmotic pressure are the principal mechanisms contributed. Moreover, Fickian type was the dominant mechanism at all duration of release. However, it was discovered using Peppas–Sahlin model that the contribution of the diffusion mechanism decreases with increasing flow rate and initial dosage. Furthermore, the tests at different drug dosages showed that the number of stages in medication release profile is independent of the flow rate and the medicine percentage. One can conclude that the drug release kinetic in static state is more influenced by drug dosage compared with dynamic state

Development of a Model Based on Physical Mechanisms for the Explanation of Drug Release: Application to Diclofenac Release from Polyurethane Films

In this study, we present a method for prediction of the drug-release profile based on the physical mechanisms that can intervene in drug release from a drug-carrier. The application presented here incorporates the effects of drug concentration and Reynolds number defining the circulating flow in the testing vein. The experimental data used relate to the release of diclofenac from samples of non-degradable polyurethane subjected to static and continuous flow. This case includes simultaneously three mechanisms: burst-release, diffusion and osmotic pressure, identified beforehand here as being able to contribute to the drug liberation. For this purpose, authors coded the Sequential Quadratic Programming Algorithm to solve the problem of non-linear optimization. The experimental data used to develop the mathematical model obtained from release studies carried out in water solution at 37 °C, for three concentrations of diclofenac and two water flow rates. We discuss the contribution of mechanisms and kinetics by considering two aforementioned parameters and, following that, we obtain the specific-model and compare the calculated results with the experimental results for the reserved cases. The results showed that drug percentage mostly affect the burst release, however flow rate has affected the osmotic release. In addition, release kinetics of all the mechanisms have increased by increasing the values of two considered parameters