Cliff retreat and sea bed morphology under monochromatic wave forcing: Experimental study

Wave flume experiments have been performed to investigate a sandy cliff recession under monochromatic wave forcing. We varied the wave climate through the wave energy flux F and the surf similarity parameter j. The various processes of the cliff erosion cycle are depicted. The sea bed evolution mostly depends on the surf similarity parameter j. Steep planar (j > 0.7), gentle planar (0.5 < j < 0.7) and bared (j < 0.5) profiles are observed. We observed different bar dynamics, including steady and unsteady self-sustained oscillating states. Then we analyze the role of the eroded material on the cliff recession rate. We show that the cliff recession rate increases with the wave energy flux. Moreover, for a given wave energy flux, it is larger for a gentle planar profile than for a bared profile. However it is similar for both a bared profile and a steep planar profile. The cliff recession rate is not a monotonic function of the cliff height as the type of bottom profile influences the wave energy at the cliff

3D Face Messaging On A Watch

A system and method are disclosed that may send a video-like message to a receiver even when the receiver is offline. The system includes a user smart device incorporating an application, and a receiver smart device incorporating the similar application. The method captures a single 2D image of the user’s face using a camera incorporated in the communication device. The 2D image of the user’s face is then recreated as a 3D model. The message to be sent to a receiver is recorded as an audio message and sent along with the 3D model. At the receiver end the audio message is played back with facial movements of the user that correspond to the speech signals sent by the user. The method is incorporated as an application in a smart-watch. The method offers video-like messaging experience at a low computational cost and requires low bandwidth. KEYWORDS: voice messaging, smart-watch, low bandwidth, video-like messagin

Sediment processes and flow reversal in the undular tidal bore of the Garonne River (France)

A tidal bore is a series of waves propagating upstream as the tidal flow turns to rising, and the bore front corresponds to the leading edge of the tidal wave in a funnel shaped estuarine zone with macro-tidal conditions. Some field observations were conducted in the tidal bore of the Garonne River on 7 June 2012 in the Arcins channel, a few weeks after a major flood. The tidal bore was a flat undular bore with a Froude number close to unity: Fr1 = 1.02 and 1.19 (morning and afternoon respectively). A key feature of the study was the simultaneous recording of the water elevation, instantaneous velocity components and suspended sediment concentration (SSC) estimates, together with a detailed characterisation of the sediment bed materials. The sediment was some silty material (d50 ≈ 13 μm) which exhibited some non-Newtonion thixotropic behaviour. The velocity and SSC estimate were recorded simultaneously at high frequency, enabling a quantitative estimate of the suspended sediment flux at the end of the ebb tide and during the early flood tide. The net sediment flux per unit area was directed upstream after the bore, and its magnitude was much larger than that at end of ebb tide. The field observations highlighted a number of unusual features on the morning of 7 June 2012. These included (a) a slight rise in water elevation starting about 70 s prior to the front, (b) a delayed flow reversal about 50 s after the bore front, (c) some large fluctuations in suspended sediment concentration (SSC) about 100 s after the bore front and (d) a transient water elevation lowering about 10 min after the bore front passage. The measurements of water temperature and salinity showed nearly identical results before and after the tidal bore, with no evidence of saline and thermal front during the study

Field Measurements in the tidal bore of the Garonne River after a recent flood

A tidal bore is a natural phenomenon associated with the rising flood tide. Composed of surface waves, it may occur in estuaries and propagate up rivers. The present study was conducted in the Garonne River (France) in the Arcins channel. Using an ADV unit and further recording equipments, experimental data are collected during a flat undular bore with a bore Froude number close to unity. Velocity analysis and sediment characterisation revel a slight rise in water elevation starting about 70 s prior to the front and a flow reversal about 50 s after the bore front. The turbulent transport of suspended sediment is presented in term of mass flux per unit area highlighting a negative (upriver) sediment mass transfer

Suivi rhéologique du processus d'agrégation de la protéine tau

International audienceAlzheimer's disease is one of thirty pathology called conformational disease that are characterized by errors folding and assembly of protein. In Alzheimer's disease, tau protein and amyloid beta peptide are responsible of the neuronal degeneration. Understanding these mechanisms and diagnosis are closely linked to the availability of an efficient analytical concept for monitoring ex vivo self-assembly of proteins. To understand the aggregation's mechanism, a microsystem is developed for the detection of protein tau based on the micro-rheological followed by high frequency ultrasonic waves. The sensor used is a TSM (Thickness Shear Mode) resonator operating in shear mode at a fundamental frequency of 5MHz. In contact with the fluid to be characterized, the sensor generate shear waves, which are measured in reflection through instrumentation developed in the laboratory. From the measurement of the complex impedance of quartz with a network analyzer, the extraction of G' (elastic modulus) and G'' (viscous modulus) is possible. Initial results indicate that our sensor can quantify, by viscosity, concentration variations of a peptide sequence of tau protein, and can differentiate, by plasticity, the conformational state.  </p

Towards a rigorous use of SPEM

International audienceModeling software process is a good way to improve development and thus quality of resulting applications. The OMG proposes the SPEM metamodel to describe software processes. Its concepts are described through class diagrams. Unfortunately, it lacks a formal description of its semantics that makes it hard to use. So, we propose a specialization of SPEM that clarifies it and we use OCL to formally express constraints on it

Etude expérimentale de l'érosion d'un massif de sable cohésif par une houle monochromatique

La plupart des côtes de la Terre reculent et 80% sont rocheuses. La prévision du recul des falaises littorales est primordiale afin d’anticiper les risques futurs pour les aménagements littoraux. Cependant, la compréhension de ce recul est difficile car de nombreux paramètres le contrôlent. Des expériences en canal à houle de petite échelle ont été effectuées où nous avons mis en place un massif de sable humide soumis à l’attaque des vagues par sapement. Le but est de comprendre comment l’effet des vagues contrôle l’érosion des falaises. La technique de mesure par ombroscopie a été employée et nous a permis de détecter la surface du sable et la surface libre en fonction du temps. Nous avons ainsi analysé l’influence du forçage des vagues (F, ξ) (où F est le flux d’énergie des vagues incidentes au large et ξ est le paramètre de similitude de “surf”) sur la vitesse de recul de la falaise et sur la profondeur des évènements d’effondrement. La vitesse de recul de la falaise augmente linéairement avec le flux d’énergie F. Les débris de falaise érodés changent la morphologie du fond, les types de morphologie du fond dépendent fortement du paramètre de similitude de “surf” au déferlement, ou encore du paramètre de Dean Ω. Des profils du fond instationnaires présentant une oscillation auto-entretenue de la barre sédimentaire ont été observés. Nous avons de plus étudié l’effet de la granulométrie du sable utilisé : pour un sable plus fin, la falaise est plus cohésive et s’effondre au cours d’évènements de plus grande ampleur. Etonnamment, le recul de la falaise est plus important pour du sable fin. Ceci est probablement dû à une modification de la morphologie du fond conduisant à une dissipation de l’énergie des vagues moins importante. Le volume de sable injecté dans le système a finalement été quantifié, la barre sédimentaire a d’abord été prélevée périodiquement et il a été observé que la vitesse de recul de la falaise vr est constante. Puis, la hauteur de falaise a été modifiée, le recul des falaises est plus important pour des petites falaises. Il semblerait que l’instationnarité d’un profil du fond se déclenche à partir d’un volume seuil de sable érodé. ABSTRACT : Most of the Earth coasts recedes and 80 % are rocky. Prediction of sea-cliff recession is essential to anticipate future risks for coastal development. However, it is difficult to understand this recession because many parameters control it. In addition, both the space and time scales are too big for the different mechanisms of cliff erosion to be fully analysed. Experiments in a small-scale wave flume were conducted in which a massif made of wet sand is submitted to wave attack. The aim is to understand how cliff erosion is wave-controlled. The technique of shadow graph measurements was used to detect the time evolution of sand and water surfaces. We have analyzed the influence of wave forcing (F, ξ) (where F is the incident offshore wave energy flux and ξ is the surf similarity parameter) on the cliff recession rate and on collapse event size. The cliff recession rate increases linearly with the wave energy flux F. The eroded cliff materials change the bottom morphology ; the types of bottom morphology strongly depend on the surf similarity parameter at the breaker point, or the Dean parameter Ω. Bottom profiles characterized by unsteady self-sustained sandbar oscillation were observed. In addition, we studied how sand granulometry change the system evolution. Finer the sand is, more cohesive is the cliff and bigger are cliff collapses. Contrary to what was expected, cliff recession is more important for a finer sand : this could be due to a more dissipative bottom morphology built by fine sands. The sand volume within the system changes following cliff collapses and a sandbar removal during particular experiments. The cliff recession rate is constant when the sandbar is removed and decreases with cliff height. It seems that the unsteadiness of the bottom profile is activated when the volume of eroded sand exceeds a threshold value

Étude expérimentale de la turbulence de grille sur le transport sédimentaire

L’objectif de cette étude est double : caractériser le transport sédimentaire dans un écoulement turbulent homogène et isotrope afin de valider les modèles utilisés dans les simulations numériques sous des conditions d’écoulement contrôlées et stabilisées ; développer une méthodologie de mesures transposables à un canal long (10 m) dans le cas d’un écoulement turbulent à surface libre généré par une onde de propagation représentant les conditions d’un mascaret. L’écoulement est généré dans une veine hydraulique rectangulaire de 1.5 m de long de section carrée (10 cm de côté). La turbulence est développée par une grille à mailles carrées (maille de 6.6 mm) choisie de manière à obtenir une faible décroissance spatiale de l’intensité turbulente soit environ 4-5% sur la majeure partie de la veine. Dans une première partie, une analyse sans particules est faite sur la base de mesures LDV (Laser Doppler Velocimetry) afin de qualifier l’écoulement de transport. Le taux de dissipation d’énergie turbulente est estimé et les différentes échelles de la turbulence sont analysées. Le mouvement des particules injectées (PMMA) est ensuite quantifié par des mesures PIV (Particle Image Velocimetry) pour différentes concentrations. Une technique de mesures par fluorescence permet de distinguer la contribution de chaque taille de particule injectée. Une analyse en termes de flux de concentration, champs de vitesses et structure de l’écoulement lors du transport sédimentaire de deux tailles caractéristiques de particules (20 et 200 µm) est présentée. Les résultats sont comparés avec des données numériques

European Federation for Exploratory Medicines Development Lyon Conference 2019 : the changing landscape of early medicines development : be prepared

The second biennial conference of the European Federation for Exploratory Medicines Development (EUFEMED) was the result of a continued effort of EUFEMED to gather all stakeholders of exploratory clinical drug development to evaluate and discuss recent developments in the field. The conference focused on how the landscape around early clinical development is changing and how clinical pharmacologists might prepare for these changes. A preconference workshop gave consideration to the impact that modeling and simulation, including physiology-based pharmacokinetic strategies, is having on the practice of clinical development. A second workshop looked at the challenges introduced by biological agents. The keynote address explored the potential role of virtual trials in early medicines development with emphasis on how models can help to understand and inform the drug development process. Presentations that followed covered a broad range of subjects including the potential impact of digital support on study performance in early phase development, extending from recruitment to remote data collection, lay person summaries, data transparency, and ethical considerations for trials in healthy subjects. The second day of the conference focused on future regulatory challenges in the field of early clinical development (including Brexit) and how to prepare for changes in the landscape. Subjects covered included new approaches and designs in oncology, the introduction of more complex study designs and digital biomarkers. Presentations given by invited speakers are published at https://www.eufemed.eu/download-presentations-of-the-lyon-conference-2019/