Influence of geometrical parameters on the flexural rigidity of the LHC dipole cold mass assembly

In order to predict the mechanical behavior of the LHC dipole cold mass in situations such as handling, transport and cool down, a number of important structural parameters are required. The dipole's flexural rigidity determines entirely the mechanical elastic behavior of the cold mass. Therefore, models of a bent cold mass were created to calculate its rigidity. This paper presents a simplified parametric finite element model, created to study the deflection of the cold mass in different situations and supporting conditions. The sensitivity of the models to the supporting conditions is computed. To provide the finite element and the analytical models with input, the deflection of the cold mass under discrete loads in normal condition and then 90-degrees rotated were measured with a laser tracker. By comparing models with measurements, the vertical and transversal rigidity of the cold mass assembly are determined. Additionally, the paper reports on the plastic behavior of the cold mass assembly in the range of the deformations that are needed to correct cold masses that result, after final welding of the outer skin, with unacceptable sagitta

Lattice points in rational ellipsoids

AbstractWe combine exponential sums, character sums and Fourier coefficients of automorphic forms to improve the best known upper bound for the lattice error term associated to rational ellipsoids

Landmark learning in a navigation task is not affected by the female rats' estrus cycle

In two experiments rats were required to escape from a circular pool by swimming to an invisible platform that was located in the same place relative to one configuration of two landmarks (X and Y). The two landmarks were placed relatively far and equidistant from the hidden platform. Training could be either on consecutive days (Experiment 1) or every fourth day (Experiment 2). Subsequent test trials, without the platform, revealed a preference for searching in the correct quadrant of the pool. In Experiment 1 such a test performance was identical in two groups of females, one tested with high hormonal levels (i.e., in the proestrus phase) and the second one tested with low hormonal levels (i.e., either in the estrus, metaestrus or diestrus phase); in addition, these two groups differed from a third group of male rats (i.e., males had a better performance than females). Experiment 2 replicated the females' previous results with a better procedure. The experiment compared the performance of two groups of female rats which were both trained and tested always in the same estrus phase, one group in the proestrus phase, and the second group in the estrus phase. The implication of these results is that the estrus cycle has little impact on the performance of female rats when landmark learning in a navigation task

Directional cue and landmark configurations: The effect of rotating one set of landmarks relative to another

This is the author accepted manuscript. The final version is available from the American Psychological Association via the DOI in this recordIn this article we addressed the question whether rats can use distal landmarks as directional cues that are used in combination with other proximal landmark configurations. The animals were trained with an A, B, C, and D landmark configuration in the Morris pool, where B and C are the near (to platform) landmarks and A and D the far ones. We also added another more distal "directional" cue Z (a white strip attached to the black curtain surrounding the pool). Experiment 1 shows a robust detrimental effect on the time spent by the rats swimming in the platform quadrant when the location of all landmarks was "Inverted" (rotated by 180 degrees) with respect to Z. A similar detrimental effect was found when, after the inversion manipulation, the locations of the near and far landmarks were "Flipped" (B swapped with C and A with D). Rats in both Inverted and Flipped tests spent more time in the Z quadrant compared to the platform quadrant (BC). Experiment 1b provided evidence distinguishing between alternative explanations of how the directional cue Z acts in combination with the other landmarks. The results from both experiments show that Z operates differently to the standard landmarks. It can function as a beacon in its own right. It can also combine with the other landmarks to produce a high level of search performance, in a way that we hypothesize to be distinct from that described by the configural analysis often applied to multiple landmarks.European Union Horizon 2020Economic and Social Research Council (ESRC

Learning in a navigation task: The role of salience of pairs of landmarks and sex differences

In two experiments rats were trained to find an invisible platform in the presence of four objects or landmarks which were centred at equal intervals around the edge of the pool. One pair of landmarks had more intrinsic salience than the other pair: The relative proximal from the platform landmarks were those with more intrinsic salience in Experiment 1 and those with less intrinsic salience in Experiment 2. In Experiment 1, the two proximal from the platform and with more intrinsic salience landmarks prevented learning about the two relatively distal from the platform and with less intrinsic salience landmarks. No sex differences were found. In Experiment 2, the two relatively distal and with more intrinsic salience landmarks did not prevent learning about the two proximal but with less intrinsic salience landmarks. No sex differences were found after extended training. These results could have implications to understand spatial overshadowing among landmarks

Aprendizaje en una tarea de navegación: el papel de la saliencia de pares de puntos de referencia y diferencias de sexo

In two experiments rats were trained to find an invisible platform in the presence of four objects or landmarks which were centred at equal intervals round the edge of the pool. One pair of landmarks had more intrinsic salience than the other pair: The relative proximal from the platform landmarks were those with more intrinsic salience in Experiment 1 and those with less intrinsic salience in Experiment 2. In Experiment 1, the two proximal from the platform and with more intrinsic salience landmarks prevented learning about the two relatively distal from the platform and with less intrinsic salience landmarks. No sex differences were found. In Experiment 2, the two relatively distal and with more intrinsic salience landmarks did not prevent learning about the two proximal but with less intrinsic salience landmarks. No sex differences were found after extended training. These results have implications to understand spatial overshadowing among landmarks.En dos experimentos se entrenó a unas ratas a encontrar una plataforma oculta en presencia de cuatro objetos o puntos de referencia, centrados a inter-valos regulares alrededor del borde de la piscina. Una pareja de puntos de referencia tenía mayor saliencia intrínseca que el otro par: los objetos más próximos de la plataforma eran los que tenían más saliencia intrínseca en el Experimento 1 y los que tenían menos en el Experimento 2. En el Experimento 1, los dos objetos más próximos de la plataforma y con más saliencia intrínseca impidieron el aprendizaje de los dos objetos más alejados de la plataforma y con menos saliencia intrínseca. No se encontraron diferencias de sexo. En el Experimento 2 los dos objetos más alejados de la plataforma y con más saliencia intrínseca no impidieron el aprendizaje de los dos objetos más próximos de la plataforma aunque con menos saliencia intrínseca. No se encontraron diferencias de sexo con un entrenamiento prolongado. Estos resultados tienen implicaciones para entender el ensombrecimiento espacial entre puntos de referencia

The LHC Dipole Geometry as Built in Industry

The LHC dipoles magnets are produced in 5 industrial production sites in Europe. The production is well underway and more than half of the total quantity has been delivered to CERN. One of the important characteristics of the dipole magnets is their geometry. To achieve the requested mechanical tolerances on the magnets, which are 15 m long and have a 28 t mass, the final assembly operations includes precise optical measurements. To ensure the good quality and high production rate, the final assembly procedure has been automated as much as possible. The authors report here about the assembly procedure, the features of the software that guides the optical measurements (and consequently the assembly operations) and the results obtained on the geometry in the different sites

Real time motion estimation using a neural architecture implemented on GPUs

This work describes a neural network based architecture that represents and estimates object motion in videos. This architecture addresses multiple computer vision tasks such as image segmentation, object representation or characterization, motion analysis and tracking. The use of a neural network architecture allows for the simultaneous estimation of global and local motion and the representation of deformable objects. This architecture also avoids the problem of finding corresponding features while tracking moving objects. Due to the parallel nature of neural networks, the architecture has been implemented on GPUs that allows the system to meet a set of requirements such as: time constraints management, robustness, high processing speed and re-configurability. Experiments are presented that demonstrate the validity of our architecture to solve problems of mobile agents tracking and motion analysis

The Highly Oscillatory Behavior of Automorphic Distributions for SL(2)

Automorphic distributions for SL(2) arise as boundary values of modular forms and, in a more subtle manner, from Maass forms. In the case of modular forms of weight one or of Maass forms, the automorphic distributions have continuous first antiderivatives. We recall earlier results of one of us on the Holder continuity of these continuous functions and relate them to results of other authors; this involves a generalization of classical theorems on Fourier series by S. Bernstein and Hardy-Littlewood. We then show that the antiderivatives are non-differentiable at all irrational points, as well as all, or in certain cases, some rational points. We include graphs of several of these functions, which clearly display a high degree of oscillation. Our investigations are motivated in part by properties of "Riemann's nondifferentiable function", also known as "Weierstrass' function".Comment: 27 pages, 6 Figures; version 2 corrects misprints and updates reference