Session C4: Development of Passive Monitoring Tools of Silver Eel Migration to Trigger Turbine Management for Fish Protection

Abstract: Reduction of fish mortality at hydropower facilities is an intense field of research for Power Companies. Nowadays, reduction of turbine capacity seems the most efficient methods, but require to be able to restrict the turbine management operations precisely to fish migration peaks to reduce loss of production to its minimum. Based on the IchtyosTM fish counting system that we use regularly to assess fish upstream migration in fish passes with a combination of laser-beams and video records, we recently adapted this technology to a silver eel specific pipe-like bypass installed at two hydropower facilities in Germany. The association of infrared-cells and video records allowed us to record automatic detection results and video samples on a local hard disk remotely connected. A specific algorithm is being developed over the study still on going with very encouraging results in terms of counting and measuring eels. The system is intended to send an automatic signal to an operator in case of eel passage detections who will then confirm it by the associated video sequence to finally start a turbine management procedure if necessary. One counting device could be used to manage several successive HPP in a river system based on real lecture of fish migration, while several devices might be required as local factors could influence eel migration patterns. This system presents the advantages to be a passive observation method, which is not invasive for fish, contrary to fish telemetry that needs to catch and surgically tag the fish. However, telemetry studies are still very important to assess fish behaviour and for instance improve the position of a fish counting system in the vicinity of HPP. Moreover, the global efficiency of an automatic counting and warning system can only be assessed by the use of telemetry studies

Spawning movements of European grayling Thymallus thymallus in the River Aisne (Belgium)

In three consecutive years (1998 to 2000), 20 adult grayling Thymallus thymallus (L.) (FL +/- SD: 326 +/- 43 mm) were radio-tracked during circum reproduction period (February to May) in the River Aisne, Belgium. Before the spawning period, grayling remained consistently in the pool-riffle sequence in which they had been captured. Pre-spawning migration time extended from 7 to 29 March. Distances travelled during the spawning migration ranged from 70 to 4980 in (mean +/- S.E.: 1234 +/- 328 m). Spawning migrations stalled under conditions of decreasing water level and increasing water temperature in a thermal range (daily mean Tdegrees) from 5 to 8 degreesC. Spawners remained from 1 to 31 days (mean +/- S.D.: 10.4 +/- 9.8 days) at the spawning grounds and performed a post-spawning homing from 28 March to 18 April in decreasing water flow and in a thermal range (daily mean Tdegrees) from 7 to 11 degreesC. This study demonstrates that migration patterns of grayling are similar between years, but with a timing adjusted as a response to annual variations of the hydroclimatic conditions

Admittance control for collaborative dual-arm manipulation

Human-robot collaboration is an appealing solution to increase the flexibility of production lines. In this context, we propose a kinematic control strategy for dual-arm robotic platforms physically collaborating with human operators. Based on admittance control, our approach aims at improving the performance of object transportation tasks by acting on two levels: estimating and compensating gravity effects on one side, and considering human intention in the cooperative task space on the other. An experimental study using virtual reality reveals the effectiveness of our method in terms of reduced human energy expenditure

Interpretable Prediction of Post-Infarct Ventricular Arrhythmia using Graph Convolutional Network

International audienceHeterogeneity of left ventricular (LV) myocardium infarction scar plays an important role as anatomical substrate in ventricular arrhythmia (VA) mechanism. LV myocardium thinning, as observed on cardiac computed tomography (CT), has been shown to correlate with LV myocardial scar and with abnormal electrical activity. In this project, we propose an automatic pipeline for VA prediction, based on CT images, using a Graph Convolutional Network (GCN). The pipeline includes the segmentation of LV masks from the input CT image, the short-axis orientation reformatting, LV myocardium thickness computation and mid-wall surface mesh generation. An average LV mesh was computed and fitted to every patient in order to use the same number of vertices with point-to-point correspondence. The GCN model was trained using the thickness value as the node feature and the atlas edges as the adjacency matrix. This allows the model to process the data on the 3D patient anatomy and bypass the “grid” structure limitation of the traditional convolutional neural network. The model was trained and evaluated on a dataset of 600 patients (27% VA), using 451 (3/4) and 149 (1/4) patients as training and testing data, respectively. The evaluation results showed that the graph model (81% accuracy) outperformed the clinical baseline (67%), the left ventricular ejection fraction, and the scar size (73%). We further studied the interpretability of the trained model using LIME and integrated gradients and found promising results on the personalised discovering of the specific regions within the infarct area related to the arrhythmogenesis

Migration behaviour of Atlantic salmon smolts (Salmo salar L.) in a short and highly fragmented gravel-bed river stretch

peer reviewedThe succession of migration barriers and different turbine types during downstream migration impede Atlantic salmon (Salmo salar L.) smolts from reaching the sea in time but is poorly studied. We investigated the isolated and cumulative impacts of 14 consecutive migration barriers (MBs) on downstream migration of 200 radio-tagged smolts over an 18.9 km stretch of gravel-bed river, by equipping five MBs with automated radio listening stations. At the level of isolated barriers, median research times (i.e. time between the first and the last detection upstream of a MB) varied between 0.1 and 0.7 h. The median crossing delays (i.e. time between the first detection upstream and the first detection downstream of a MB) varied between 1 and 2.9 h. Considering successive MBs, median cumulative crossing delays varied between 2.6 and 32.1 h and increased with the number of MBs. We observed a global mortality rate between 33% and 76%, increasing with the distance travelled and the associated number of MBs. Only 48% of the migrating smolts reached the end of the studied river stretch. Results suggest that the dynamics of the smolt downstream migration over this short highly fragmented stretch had a significant effect in terms of delays, mortalities and seaward escapement rate