DJ1 at the interface between neuro-degeneration and cancer

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Adaptive and Safe Bayesian Optimization in High Dimensions via One-Dimensional Subspaces

Bayesian optimization is known to be difficult to scale to high dimensions, because the acquisition step requires solving a non-convex optimization problem in the same search space. In order to scale the method and keep its benefits, we propose an algorithm (LineBO) that restricts the problem to a sequence of iteratively chosen one-dimensional sub-problems that can be solved efficiently. We show that our algorithm converges globally and obtains a fast local rate when the function is strongly convex. Further, if the objective has an invariant subspace, our method automatically adapts to the effective dimension without changing the algorithm. When combined with the SafeOpt algorithm to solve the sub-problems, we obtain the first safe Bayesian optimization algorithm with theoretical guarantees applicable in high-dimensional settings. We evaluate our method on multiple synthetic benchmarks, where we obtain competitive performance. Further, we deploy our algorithm to optimize the beam intensity of the Swiss Free Electron Laser with up to 40 parameters while satisfying safe operation constraints

Loss Comparison of Small Delta- and Star-Connected Permanent Magnet Synchronous Machines

Delta-connected stator windings are often used in mass production of small Permanent Magnet Synchronous Machines (PMSMs). In comparison to star-connected stator windings, a delta-connected winding system offers advantages for manufacturing and lowers production costs. A main disadvantage of motors with such a winding system are additional losses caused by the Zero-Sequence Current Component (ZSCC). In this paper the ZSCC and its impact on the generated losses in a delta-connected PMSM used as a traction motor for a pedal electric cycle (Pedelec) is analysed. The calculated results are compared to those of a star-connected PMSM with the same design. We will show that the amplitude of the ZSCC depends on the operating point of the machine. As a result, the copper losses in the delta-connected machine are up to 5.8 % higher than the ones in the star-connected machine. On the other hand, the iron losses are 1 % smaller in the delta-connected machine. The efficiency of the delta-connected machine is still up to 4 % smaller

A New Resistive Adaptive Gate-Driving Concept with Automated Identification of Operational Parameters

This paper proposes a new adaptive gate-driving concept based on parallel-connected resistive driving stages, which allows the modification of the effective gate-resistance for every turn-on and turn-off event during operation. By selecting the appropriate gate-resistance, the switching behavior can be optimized individually for each specific operating point (Vsw, Isw, Tj). As a result, higher efficiency under partial load can be achieved. The selection of effective gate-resistance is based on the results of a here introduced automatic optimization method, which takes constraints such as dv/dt- and di/dt-limits into account. Subject of this paper is also the comparison of the new approach with the widely used single-stage resistive driver

Identification of rotor and stator flux linkage maps of squirrel cage induction motors based on identification of rotor time constant maps

Model-predictive, field-oriented control of squirrel cage induction motors (SCIM) depends on the accurate identification and orientation of rotor and stator flux maps. In this paper, a new method is presented that utilizes the measured rotor time constant maps to reduce the orientation error of the identified flux maps. This enables the identification and modelling of the nonlinear and transient machine behavior, due to the estimation of the stator- and rotor-flux maps in dependence of stator and rotor currents

Design of a Modular Multilevel Converter with 400 kWh of Integrated Batteries

In this paper the electromechanical design and the cascaded signal processing platform of a modular multilevel converter with integrated, second-life battery modules are presented. With its 120 full-bridge submodules, the prototype is designed for a maximum in- and output power of 100 kW and to store up to 400 kWh