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The paper presents a numerical study on electrodynamic behavior of the inter-pancake twin-box joints of the Poloidal Field (PF) coils of the ITER Magnet System. This work was carried out with the THELMA code, developed at the University of Bologna. The THELMA model was adapted to describe both the superconducting wires and the resistive saddle of the joint in a set of reference configurations representative of a set of experimental tests performed on a joint sample at the SULTAN facility in Villigen, Switzerland. The model was applied to analyze both the DC joint resistance measurements and the AC loss vs frequency curve, in order to obtain a full representation of the joint electromagnetic behavior. The paper reports a comparison between the numerical and experimental results and parametric studies on the impact of the main model parameters on the loss vs frequency curve. [ABSTRACT FROM AUTHOR]

At the Paul Scherrer Institute (PSI) in Switzerland, cancer patients are treated with protons. The PSI Gantries work with Pencil Beam Scanning (PBS) technology. For beam profile characterization, a new 2-D planar pixel detector based on Printed Circuit Board technology was developed. The main challenge of the design was the limited amount of 256 readout channels while several thousands of detector signals had to be processed. With PBS, only a few pixels will be hit by the proton beam and give a significant signal, while most of them will not capture any signal. On the detector design, the active area was divided into pixel arrays with equal size, while one array is such big to cover the whole size of the proton beam. By a so-called channel recycling technique, the same pixel number of all pixel arrays were connected together to one readout channel. The proof of concept was verified with a small detector. In the next step, the design was changed such, getting a full-scale detector for Gantry 2. The readout electronics board itself is also a development performed at PSI. A core component of the design is the ADAS1128 chip from ANALOG Devices featuring 128 input channels. The pixel detector is fully integrated into the therapy control system (TCS) through readout electronics with a field-programmable gate array (FPGA) technology. The FPGA technology allows to readout the detector synchronized to the beam delivery. This paper summarizes the features of the pixel detector design, the readout electronics, and shows the first experimental results. [ABSTRACT FROM AUTHOR]

This paper proposes a novel unsupervised damage detection approach based on a memetic algorithm that establishes the normal or undamaged condition of a structural system as data clusters through a global xpectation–maximization technique, using only damage-sensitive features extracted from output-only vibration measurements. The health state is then discriminated by considering the Mahalanobis squared distance between the learned clusters and a new observation. The proposed approach is compared with state-of-the-art ones by taking into account real-world data sets from the Z-24 Bridge (Switzerland), where several damage scenarios were performed. The results indicated that the proposed approach can be applied in structural health monitoring applications where life safety, economic, and reliability issues are the most important motivations to consider. [ABSTRACT FROM AUTHOR]

The uncontrolled growing number of resident space objects (RSOs) threatens the safe operation of space-related activities. Since the beginning of the Space Age, outer space is getting populated by objects emerging after breakup events; spare components through launching, orbiting, and aging of satellite missions; collisions between functional or defunct RSOs; or by missions that either completed or began their life cycle. One potential measure toward the sustainable use of outer space may start by preventing collisions between existing RSOs. Collisions between existing RSOs will only exacerbate the current situation, which could lead to a cascade effect known as the Kessler syndrome. In the context of such collisions, the enabling of optical daylight tracking has the potential to reduce the uncertainty of the estimated state vector for each RSO, thus aiding the planning and execution of efficient avoidance maneuvers when a collision is foreseeable, as well as benefiting just-in-time collision avoidance strategies in the future. This study starts by analyzing the impact of optical daylight observations, within the domain of defunct RSOs, with respect to the currently restricted nighttime observation windows, the type of observable acquired by the observing station, and the relative geometry between the Sun, the RSO, and the ground station. We highlight the role of key hardware components on each observing system deemed critical for current observing optical ground stations to enable daylight measurement acquisition. Once we have inspected all factors deemed crucial for daylight observations in our system, we present successful daylight observations, from which we derived angular observables, ranges, and apparent brightness. We additionally provide an example where the combination of measurements acquired by the different systems, operating in the optical regime only, contributed to partial disambiguation of the tumbling motion of a selected rocket body. All observations were conducted using a scientific complementary-metal-oxide-semiconductor (CMOS) sensor and a geodetic laser ranging system. Both systems make use of the 1-m Zimmerwald laser and astrometry telescope (ZIMLAT) for measurement acquisition and target RSO tracking at the Swiss Optical Ground Station and Geodynamics Observatory Zimmerwald (SwissOGS), operated by the Astronomical Institute of the University of Bern, Switzerland. [ABSTRACT FROM AUTHOR]

The modular Snow Microwave Radiative Transfer (SMRT) model simulates microwave scattering behavior in snow via different selectable theories and snow microstructure representations, which is well suited to intercomparisons analyses. Here, five microstructure models were parameterized from X-ray tomography and thin-section images of snow samples and evaluated with SMRT. Three field experiments provided observations of scattering and absorption coefficients, brightness temperature, and/or backscatter with the increasing complexity of snowpack. These took place in Sodankylä, Finland, and Weissfluhjoch, Switzerland. Simulations of scattering and absorption coefficients agreed well with observations, with higher errors for snow with predominantly vertical structures. For simulation of brightness temperature, difficulty in retrieving stickiness with the Sticky Hard Sphere microstructure model resulted in relatively poor performance for two experiments, but good agreement for the third. Exponential microstructure gave generally good results, near to the best performing models for two field experiments. The Independent Sphere model gave intermediate results. New Teubner–Strey and Gaussian Random Field models demonstrated the advantages of SMRT over microwave models with restricted microstructural geometry. Relative model performance is assessed by the quality of the microstructure model fit to micro-computed tomography (CT) data and further improvements may be possible with different fitting techniques. Careful consideration of simulation stratigraphy is required in this new era of high-resolution microstructure measurement as layers thinner than the wavelength introduce artificial scattering boundaries not seen by the instrument. [ABSTRACT FROM AUTHOR]

We consider autonomous racing of two cars and present an approach to formulate racing decisions as a noncooperative nonzero-sum game. We design three different games where the players aim to fulfill static track constraints as well as avoid collision with each other; the latter constraint depends on the combined actions of the two players. The difference between the games is the collision constraints and the payoff. In the first game, collision avoidance is only considered by the follower, and each player maximizes their own progress toward the finish line. We show that, thanks to the sequential structure of this game, equilibria can be computed through an efficient sequential maximization approach. Furthermore, we show that these actions, if feasible, are also a Stackelberg and Nash equilibrium in pure strategies of our second game where both players consider the collision constraints. The payoff of our third game is designed to promote blocking, by additionally rewarding the cars for staying ahead at the end of the horizon. We show that this changes the Stackelberg equilibrium, but has a minor influence on the Nash equilibria. For online implementation, we propose to play the games in a moving horizon fashion and discuss two methods for guaranteeing feasibility of the resulting coupled repeated games. Finally, we study the performance of the proposed approaches in simulation for a setup that replicates the miniature race car tested at the Automatic Control Laboratory, ETH Zürich, Switzerland. The simulation study shows that the presented games can successfully model different racing behaviors and generate interesting racing situations. [ABSTRACT FROM AUTHOR]