An interface condition to compute compressible flows in variable cross section ducts

International audienceWe propose an improved interface condition in order to account for head losses in pipe when some discontinuous cross sections occur

Data Hiding of Motion Information in Chroma and Luma Samples for Video Compression

International audience2010 appears to be the launching date for new compression activities intended to challenge the current video compression standard H.264/AVC. Several improvements of this standard are already known like competition-based motion vector prediction. However the targeted 50% bitrate saving for equivalent quality is not yet achieved. In this context, this paper proposes to reduce the signaling information resulting from this vector competition, by using data hiding techniques. As data hiding and video compression traditionally have contradictory goals, a study of data hiding is first performed. Then, an efficient way of using data hiding for video compression is proposed. The main idea is to hide the indices into appropriately selected chroma and luma transform coefficients. To minimize the prediction errors, the modification is performed via a rate-distortion optimization. Objective improvements (up to 2.3% bitrate saving) and subjective assessment of chroma loss are reported and analyzed for several sequences

Exponential Adoption of Battery Electric Cars

The adoption of battery electric vehicles (BEVs) may significantly reduce greenhouse gas emissions caused by road transport. However, there is wide disagreement as to how soon battery electric vehicles will play a major role in overall transportation. Focusing on battery electric passenger cars, we here analyze BEV adoption across 17 individual countries, Europe, and the World, and consistently find exponential growth trends. Modeling-based estimates of future adoption given past trends suggests system-wide adoption substantially faster than typical economic analyses have proposed so far. For instance, we estimate the majority of passenger cars in Europe to be electric by about 2031. Within regions, the predicted times of mass adoption are largely insensitive to model details. Despite significant differences in current electric fleet sizes across regions, their growth rates consistently indicate fast doubling times of approximately 15 months, hinting at radical economic and infrastructural consequences in the near future

Deep Visual Reasoning: Learning to Predict Action Sequences for Task and Motion Planning from an Initial Scene Image

In this paper, we propose a deep convolutional recurrent neural network that predicts action sequences for task and motion planning (TAMP) from an initial scene image. Typical TAMP problems are formalized by combining reasoning on a symbolic, discrete level (e.g. first-order logic) with continuous motion planning such as nonlinear trajectory optimization. Due to the great combinatorial complexity of possible discrete action sequences, a large number of optimization/motion planning problems have to be solved to find a solution, which limits the scalability of these approaches. To circumvent this combinatorial complexity, we develop a neural network which, based on an initial image of the scene, directly predicts promising discrete action sequences such that ideally only one motion planning problem has to be solved to find a solution to the overall TAMP problem. A key aspect is that our method generalizes to scenes with many and varying number of objects, although being trained on only two objects at a time. This is possible by encoding the objects of the scene in images as input to the neural network, instead of a fixed feature vector. Results show runtime improvements of several magnitudes. Video: https://youtu.be/i8yyEbbvoEkComment: Robotics: Science and Systems (R:SS) 202

Ni:Si as Barrier Material for a Solderable PVD Metallization of Silicon Solar Cells

AbstractWe study Ni:Si as a barrier material for the PVD metallization of silicon solar cells and investigate the long term solderability of Al/Ni:Si/Ag metal stacks in terms of peel forces and contact resistances. For this purpose, solar cell connectors are soldered on the Al/Ni:Si/Ag stacks in three different aging states: directly after metallization, after accelerated storage and after storage for six months. The thickness of the Ni:Si layer is varied in these tests. Furthermore we measure the contact resistance between cell interconnect ribbons and the test stack. To assess possible contamination of the Si by the metals we measure the effective lifetime of electron hole pairs during a regularly interrupted thermal treatment procedure. The samples with 200nm or thicker Ni:Si layers soldered with the lead-containing solder and the flux 952S perform best and pass all tests