The reliability of microelectromechanical systems (MEMS) becomes increasingly important due to the fast market growth, especially in medical, automotive, and aerospace applications, where high reliability performance under harsh environmental conditions is crucial. The aim of this work is to test the behavior and performance of two-dimensional (2D) resonant MEMS mirrors, which are driven electrostatically, under different temperatures. Therefore, six mirrors and their driver application specific integrated circuits (ASIC) are tested inside a temperature chamber, where the temperature is swept between -40°C and 90°C multiple times and different mirror parameters are logged for both axes of the mirrors and the results are evaluated afterwards. Especially the driving frequencies of the axes are monitored. The results show that there is a nearly linear inverse relation between driving frequency of the mirror's fast axis and temperature, as the frequency rises with a decreasing temperature, while for the slow axis the relation between frequency and temperature is more complex. Moreover, the operation of the mirror is stable over the tested temperature range, as no failures are observed.

In this article, joint communication and sensing (JCAS) is combined with reconfigurable intelligent surfaces (RISs), which validates a novel RIS-based JCAS (RIS-JCAS) system. The proposed system performs monostatic sensing to detect a potential user, after which communication with the user is established. The corresponding RIS-cascaded channel is formulated, based on which an algorithm is created, to handle radar target detection and communication channel estimation while multiple RISs operate simultaneously. A joint beam training process by utilizing the identical beamforming pattern on multiple RISs is created, which increases the time efficiency significantly. The detection accuracy is subsequently further improved through a novel fine-tuning method. To practically validate the aforementioned algorithm, a RIS-JCAS system is demonstrated using a mmWave testbed with a bandwidth of 1 GHz centralized at 26.2 GHz. Besides combining the widely adopted orthogonal frequency-division multiplexing (OFDM) scheme with high-directional RIS beams, the system also allows the use of variant RIS flat-top beam shaping combined with orthogonal chirp-division multiplexing radar (OCDM) waveforms. This idea keeps the sensitivity of the RIS-JCAS system while broader beams with wider coverage but lower gain are utilized. Overall, accurate 4-dimensional sensing results are derived, which strongly assists the communication channel estimation and realizes the core benefits of the proposed RIS-JCAS system.

Abstract In this paper we present a novel method to approximate the force field of a discrete 3d object with a time complexity that is linear in the number of voxels. We define a rule, similar to the distance transform, to propagate forces associated with boundary points into the interior of the object. The result of this propagation depends on the order in which the points of the object are processed. Therefore we analyze how to obtain an order‐invariant approximation formula. With the resulting formula it becomes possible to approximate the force field and to use its features for a fast and topology preserving skeletonization. We use a thinning strategy on the body‐centered cubic lattice to compute the skeleton and ensure that critical points of the force field are not removed. This leads to improved skeletons with respect to the properties of centeredness and rotational invariance.