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Matthias Weiß

Publications and source records attributed to Matthias Weiß.

At least 19 recordsLinked to original sources

Self-Adaptive Anomaly Detection with Reinforcement Learning and Human Feedback in Connected Vehicles

Connected vehicles are autonomous cyber-physical systems whose behavior must be continuously monitored during operation to detect deviations from normal operation before they propagate into failures. Such evaluation is challenging because the systems themselves evolve: over-the-air updates, configuration changes, and shifting workloads alter the definition of normal behavior, causing static diagnostic methods to degrade silently over time. Existing approaches typically address either automated model adaptation or operator integration in isolation, rather than as a single coordinated supervisory loop. This paper presents an online anomaly detection framework for autonomous CPS that integrates three coordinated mechanisms. A factorized deep Q-network with self-attention selects the most suitable detector from a candidate pool for each monitored service, exploiting inter-service dependencies in the microservice topology. An ensemble of three statistical drift detectors monitors the input distribution and raises an alarm only when all three concur, prioritizing precision over recall. A human-in-the-loop retraining mechanism, built around a pending transition buffer and a 60/40 prioritized replay strategy, allows the operator to incorporate expert knowledge while preserving the system's learned response to prior data distributions. The framework is evaluated on a connected-vehicle testbed running an automated valet parking application across seven backend microservices. The attention-augmented agent achieves an F1 score of 0.69, compared to at most 0.11 for any single detector applied uniformly. Following a real software update that induces measurable concept drift, F1 drops to 0.52; after operator-triggered retraining, performance recovers to 0.65 on the new distribution while remaining at 0.69 on the prior one, demonstrating sustained adaptation without catastrophic forgetting.

cs.LG

SDVDiag: Multimodal Causal Discovery for Online Diagnosis in Software-defined Vehicles

The transition toward software-defined vehicles concentrates an increasing share of vehicle functionality into distributed software services, where failures propagate through service dependencies and the surface symptom is often several causal hops away from the underlying defect. Existing approaches to causal root-cause analysis in such systems address this only partially: they typically reason over a single observability modality and operate in an offline, operator-driven mode that does not match the demands of continuous vehicle operation. This paper presents SDVDiag, a multimodal causal-discovery pipeline that fuses log-based and metric-based service representations into a shared embedding space before graph construction, coupled with an anomaly-driven trigger that converts the diagnostic platform from a manually operated batch tool into a continuously running online system. Evaluation on an Autonomous Valet Parking testbed shows that the multimodal pipeline produces sparser causal graphs than a metrics-only baseline (134 vs. 182 edges on average) and consistently outperforms it in edge-weighted reward against an expert knowledge graph at every stage of human-feedback refinement, showing a 2.4-fold improvement over the baseline after 60 feedback queries. An end-to-end fault-injection scenario further demonstrates that the integrated trigger correctly recovers a true root cause located two causal hops upstream of the observable symptom.

cs.SE

Magnetically Programmable Surface Acoustic Wave Filters: Device Concept and Predictive Modeling

Filtering surface acoustic wave (SAW) signals of specified frequencies depending on the strength of an external magnetic field in a magnetostrictive material has garnered significant interest due to its potential scientific and industrial applications. Here, we propose a device that achieves selective SAW attenuation by instead programming its internal magnetic state. To this end, we perform micromagnetic simulations for the magnetoelastic interaction of the Rayleigh SAW mode with spin waves (SWs) in exchange-decoupled Co/Ni islets on a piezoelectric LiTaO$_3$ substrate. Due to the islets exhibiting perpendicular magnetic anisotropy, the stray-field interaction between them leads to a shift in the SW dispersion depending on the magnetic alignment of neighboring islets. This significantly changes the efficiency of the magnetoelastic interaction at specified frequencies. We predict changes in SAW transmission of 52.0 dB/mm at 3.8 GHz depending on the state of the device. For the efficient simulation of the device, we extend a prior energy conservation argument based on analytical solutions of the SW to finite-difference numerical calculations, enabling the modeling of arbitrary magnetization patterns like the proposed islet-based design.

cond-mat.mes-hall

Towards Intelligent Computation Offloading in Dynamic Vehicular Networks: A Scalable Multilayer Pipeline

Software Defined Vehicles face an increasing computational gap as advanced algorithms and frequent software updates demand more processing power while onboard hardware remains static throughout a vehicle's 10+ year lifespan. This mismatch threatens the performance of safety-critical functions including advanced driver-assistance systems and real-time perception tasks. We propose a novel four-layer computation offloading pipeline that dynamically distributes vehicular functions to cloud and edge resources while meeting strict Round Trip Time constraints. Our key contribution is an enhanced Particle Swarm Optimization algorithm that integrates distance- and direction-based penalties with functional requirements to optimize edge server selection for mobile vehicles. Evaluation using a Kubernetes-based cloud infrastructure with realistic vehicular mobility patterns demonstrates that our approach reduces average response time compared to conventional Brute-Force methods while maintaining the success rate for latency-critical tasks. The modified Particle Swarm Optimization algorithm achieves an average execution time of 26 ms across ten servers and tasks on Central Processing Unit, and 550ms across 15 servers with 1000 tasks on Graphics Processing Unit. These results confirm the pipeline's effectiveness in bridging the computational gap for next-generation Software Defined Vehicles (SDV).

cs.SE

SDVDiag: Using Context-Aware Causality Mining for the Diagnosis of Connected Vehicle Functions

Real-world implementations of connected vehicle functions are spreading steadily, yet operating these functions reliably remains challenging due to their distributed nature and the complexity of the underlying cloud, edge, and networking infrastructure. Quick diagnosis of problems and understanding the error chains that lead to failures is essential for reducing downtime. However, diagnosing these systems is still largely performed manually, as automated analysis techniques are predominantly data-driven and struggle with hidden relationships and the integration of context information. This paper addresses this gap by introducing a multimodal approach that integrates human feedback and system-specific information into the causal analysis process. Reinforcement Learning from Human Feedback is employed to continuously train a causality mining model while incorporating expert knowledge. Additional modules leverage distributed tracing data to prune false-positive causal links and enable the injection of domain-specific relationships to further refine the causal graph.Evaluation is performed using an automated valet parking application operated in a connected vehicle test field. Results demonstrate a significant increase in precision from 14\% to 100\% for the detection of causal edges and improved system interpretability compared to purely data-driven approaches, highlighting the potential for system operators in the connected vehicle domain.

cs.SE

Topical review on acousto-optical Floquet engineering of single-photon emitters

The combination of solid state single-photon emitters and mechanical excitations on a common platform is a promising approach for the development of hybrid quantum technologies. In this topical review we discuss state-of-the-art platforms for emitter-based acousto-optics and their feasibility for acousto-optical Floquet engineering. To this aim we investigate theoretically the resonance fluorescence (RF) spectrum of an acoustically modulated single-photon emitter under arbitrarily strong optical driving. In the spectrum, the combination of Mollow triplet physics and phonon sidebands results in a complex structure of crossings, anti-crossings, and line suppressions. We apply Floquet theory to develop an analytical expression for the RF spectrum. Complemented with perturbative and non-perturbative techniques, this allows us to fully understand the underlying acousto-optical double dressing physics of the hybrid quantum system, explaining the observed spectral features. We use these insights to perform an experimental feasibility study of existing emitter-based acousto-optical platforms and come to the conclusion that surface and bulk acoustic waves interfaced with quantum dots as an established Mollow triplet platform represent particularly promising infrastructures for acousto-optical Floquet engineering.

cond-mat.mes-hall

Coupling Quantum Dots to Elastic Waves in a Phononic Crystal Waveguide

We present a comprehensive study of quantum dot (QD) coupling to various phononic modes in a phononic waveguide, combining multiband kp and configuration-interaction (CI) QD state simulations with finite-element waveguide mode modeling. We consider self-assembled Stranski-Krastanov InGaAs/GaAs as well as local droplet-etched GaAs/AlGaAs structures. Using kp-CI calculations, we quantify the strain and piezoelectric responses of InAs and GaAs QDs. By systematically isolating volumetric/shear deformation-potential and piezoelectric channels, we demonstrate how mode symmetries dictate distinct coupling mechanisms. We identify the dominant coupling channels and characterize their observable signatures in the QD response. We predict strong linear energy shifts under volumetric strain and quadratic behavior under shear strain, especially in GaAs QDs. The piezoelectric effect is dominated by polarizability, which also leads to a quadratic response. The simulations show energy modulations up to 0.7 meV for an acoustic wave with 0.1 nm amplitude. The quadratic response to shear strain and piezoelectric field leads to frequency doubling in the QD response to a mechanical wave and to non-harmonic time traces when linear and quadratic effects contribute to a similar degree. The deep understanding of QD-acoustic couplings opens pathways to the optimal design of QD and waveguide structures, as well as to improved engineering of acousto-optic quantum interfaces.

cond-mat.mes-hall

Impact of Electrical Contacts on Transition Metal Dichalcogenides-Based Acoustoelectric and Acousto-Photoelectric Devices

We study the impact of electrical contact barriers in hybrid WSe$_2$-LiNbO$_3$-based acoustoelectric and acousto-photoelectric devices using a combination of scanning photocurrent and acousto-electric current spectroscopy. Static scanning photocurrent measurements provide a qualitative measure of the band-bending and spatial distribution of the Schottky barrier between semiconducting WSe$_2$ and gold electrodes whereas the surface acoustic wave-induced acousto-electric current reveals the height of the tunnelling barrier created by the van der Waals gap between the multilayered WSe$_2$ flake and the gold electrodes in addition to the Schottky barrier. The combination of both techniques shows a ten-fold increase in the photocurrent by the acoustic wave. Moreover, the observed spatial redistribution of the current is attributed to the interplay between the contact properties at the source and drain electrodes and the charge carrier dynamics induced by the surface acoustic wave. The ratio of acoustic wavelength to the electrical channel length is found to impact the SAW-induced charge carrier transport. For a channel length shorter than one acoustic wavelength, carriers undergo a seesaw-like motion which changes to charge conveyance for channel lengths comparable or exceeding the acoustic wavelength.

cond-mat.mes-hall

Modeling Magnetoelastic Wave Interactions in Magnetic Films and Heterostructures: A finite-difference approach

The (inverse) magnetostrictive effect in ferromagnets couples the magnetic properties to the mechanical stress, allowing for an interaction between the magnetic and mechanical degrees of freedom. In this work, we present a time-integration scheme for the self-consistent simulation of coupled magnetoelastic dynamics within the framework of finite-difference micromagnetism. The proposed implementation extends the Landau-Lifshitz-Gilbert equation by a strain-induced effective field and concurrently solves the elastic equation of motion, while correctly incorporating stress and strain discontinuities at material interfaces. We then present a comprehensive set of examples, ranging from static stress configurations over material boundaries to simulations of surface acoustic wave attenuation in magnetically structured thin and thick films. These computational experiments both validate the implementation and underscore the importance of properly handling jump and boundary conditions in magnon-phonon interaction studies.

physics.comp-ph

Directives for Function Offloading in 5G Networks Based on a Performance Characteristics Analysis

Cloud-based offloading helps address energy consumption and performance challenges in executing resource-intensive vehicle algorithms. Utilizing 5G, with its low latency and high bandwidth, enables seamless vehicle-to-cloud integration. Currently, only non-standalone 5G is publicly available, and real-world applications remain underexplored compared to theoretical studies. This paper evaluates 5G non-standalone networks for cloud execution of vehicle functions, focusing on latency, Round Trip Time, and packet delivery. Tests used two AI-based algorithms -- emotion recognition and object recognition -- along an 8.8 km route in Baden-Württemberg, Germany, encompassing urban, rural, and forested areas. Two platforms were analyzed: a cloudlet in Frankfurt and a cloud in Mannheim, employing various deployment strategies like conventional applications and containerized and container-orchestrated setups. Key findings highlight an average signal quality of 84 %, with no connectivity interruptions despite minor drops in built-up areas. Packet analysis revealed a Packet Error Rate below 0.1 % for both algorithms. Transfer times varied significantly depending on the geographical location and the backend servers' network connections, while processing times were mainly influenced by the computation hardware in use. Additionally, cloud offloading seems only be a suitable option, when a round trip time of more than 150 ms is possible.

cs.NI

SDVDiag: A Modular Platform for the Diagnosis of Connected Vehicle Functions

Connected and software-defined vehicles promise to offer a broad range of services and advanced functions to customers, aiming to increase passenger comfort and support autonomous driving capabilities. Due to the high reliability and availability requirements of connected vehicles, it is crucial to resolve any occurring failures quickly. To achieve this however, a complex cloud/edge architecture with a mesh of dependencies must be navigated to diagnose the responsible root cause. As such, manual analyses become unfeasible since they would significantly delay the troubleshooting. To address this challenge, this paper presents SDVDiag, an extensible platform for the automated diagnosis of connected vehicle functions. The platform enables the creation of pipelines that cover all steps from initial data collection to the tracing of potential root causes. In addition, SDVDiag supports self-adaptive behavior by the ability to exchange modules at runtime. Dependencies between functions are detected and continuously updated, resulting in a dynamic graph view of the system. In addition, vital system metrics are monitored for anomalies. Whenever an incident is investigated, a snapshot of the graph is taken and augmented by relevant anomalies. Finally, the analysis is performed by traversing the graph and creating a ranking of the most likely causes. To evaluate the platform, it is deployed inside an 5G test fleet environment for connected vehicle functions. The results show that injected faults can be detected reliably. As such, the platform offers the potential to gain new insights and reduce downtime by identifying problems and their causes at an early stage.

cs.SE

An OpenSource CI/CD Pipeline for Variant-Rich Software-Defined Vehicles

Software-defined vehicles (SDVs) offer a wide range of connected functionalities, including enhanced driving behavior and fleet management. These features are continuously updated via over-the-air (OTA) mechanisms, resulting in a growing number of software versions and variants due to the diversity of vehicles, cloud/edge environments, and stakeholders involved. The lack of a unified integration environment further complicates development, as connected mobility solutions are often built in isolation. To ensure reliable operations across heterogeneous systems, a dynamic orchestration of functions that considers hardware and software variability is essential. This paper presents an open-source CI/CD pipeline tailored for SDVs. It automates the build, test, and deployment phases using a combination of containerized open-source tools, creating a standardized, portable, and scalable ecosystem accessible to all stakeholders. Additionally, a custom OTA middleware distributes software updates and supports rollbacks across vehicles and backend services. Update variants are derived based on deployment target dependencies and hardware configurations. The pipeline also supports continuous development and deployment of AI models for autonomous driving features. Its effectiveness is evaluated using an automated valet parking (AVP) scenario involving TurtleBots and a coordinating backend server. Two object detection variants are developed and deployed to match hardware-specific requirements. Results demonstrate seamless OTA updates, correct variant selection, and successful orchestration across all targets. Overall, the proposed pipeline provides a scalable and efficient solution for managing software variants and OTA updates in SDVs, contributing to the advancement of future mobility technologies.

cs.SE

A Survey on Performance, Current and Future Usage of Vehicle-To-Everything Communication Standards

Wireless communication between road users is essential for environmental perception, reasoning, and mission planning to enable fully autonomous vehicles, and thus improve road safety and transport efficiency. To enable collaborative driving, the concept of vehicle-to-Everything (V2X) has long been introduced to the industry. Within the last two decades, several communication standards have been developed based on IEEE 802.11p and cellular standards, namely Dedicated Short-Range Communication (DSRC), Intelligent Transportation System G5 (ITS-G5), and Cellular- and New Radio- Vehicle-to-Everything (C-V2X and NR-V2X). However, while there exists a high quantity of available publications concerning V2X and the analysis of the different standards, only few surveys exist that summarize these results. Furthermore, to our knowledge, no survey that provides an analysis about possible future trends and challenges for the global implementation of V2Xexists. Thus, this contribution provides a detailed survey on Vehicle-to-Everything communication standards, their performance, current and future applications, and associated challenges. Based on our research, we have identified several research gaps and provide a picture about the possible future of the Vehicle-to-Everything communication domain.

cs.ET

Heterogeneous integration of superconducting thin films and epitaxial semiconductor heterostructures with Lithium Niobate

We report on scalable heterointegration of superconducting electrodes and epitaxial semiconductor quantum dots on strong piezoelectric and optically nonlinear lithium niobate. The implemented processes combine the sputter-deposited thin film superconductor niobium nitride and III-V compound semiconductor membranes onto the host substrate. The superconducting thin film is employed as a zero-resistivity electrode material for a surface acoustic wave resonator with internal quality factors $Q \approx 17000$ representing a three-fold enhancement compared to identical devices with normal conducting electrodes. Superconducting operation of $\approx 400\,\mathrm{MHz}$ resonators is achieved to temperatures $T>7\,\mathrm{K}$ and electrical radio frequency powers $P_{\mathrm{rf}}>+9\,\mathrm{dBm}$. Heterogeneously integrated single quantum dots couple to the resonant phononic field of the surface acoustic wave resonator operated in the superconducting regime. Position and frequency selective coupling mediated by deformation potential coupling is validated using time-integrated and time-resolved optical spectroscopy. Furthermore, acoustoelectric charge state control is achieved in a modified device geometry harnessing large piezoelectric fields inside the resonator. The hybrid quantum dot - surface acoustic wave resonator can be scaled to higher operation frequencies and smaller mode volumes for quantum phase modulation and transduction between photons and phonons via the quantum dot. Finally, the employed materials allow for the realization of other types of optoelectronic devices, including superconducting single photon detectors and integrated photonic and phononic circuits.

physics.app-ph

On-chip generation and dynamic piezo-optomechanical rotation of single photons

Integrated photonic circuits are key components for photonic quantum technologies and for the implementation of chip-based quantum devices. Future applications demand flexible architectures to overcome common limitations of many current devices, for instance the lack of tuneabilty or built-in quantum light sources. Here, we report on a dynamically reconfigurable integrated photonic circuit comprising integrated quantum dots (QDs), a Mach-Zehnder interferometer (MZI) and surface acoustic wave (SAW) transducers directly fabricated on a monolithic semiconductor platform. We demonstrate on-chip single photon generation by the QD and its sub-nanosecond dynamic on-chip control. Two independently applied SAWs piezo-optomechanically rotate the single photon in the MZI or spectrally modulate the QD emission wavelength. In the MZI, SAWs imprint a time-dependent optical phase and modulate the qubit rotation to the output superposition state. This enables dynamic single photon routing with frequencies exceeding one gigahertz. Finally, the combination of the dynamic single photon control and spectral tuning of the QD realizes wavelength multiplexing of the input photon state and demultiplexing it at the output. Our approach is scalable to multi-component integrated quantum photonic circuits and is compatible with hybrid photonic architectures and other key components for instance photonic resonators or on-chip detectors.

physics.optics

Resonance fluorescence spectral dynamics of an acoustically modulated quantum dot

Quantum technologies that rely on photonic qubits require a precise controllability of their properties. For this purpose hybrid approaches are particularly attractive because they offer a large flexibility to address different aspects of the photonic degrees of freedom. When combining photonics with other quantum platforms like phonons, quantum transducers have to be realized that convert between the mechanical and optical domain. Here, we realize this interface between phonons in the form of surface acoustic waves (SAWs) and single photons, mediated by a single semiconductor quantum dot exciton. In this combined theoretical and experimental study, we show that the different sidebands exhibit characteristic blinking dynamics that can be controlled by detuning the laser from the exciton transition. By developing analytical approximations we gain a better understanding of the involved internal dynamics. Our specific SAW approach allows us to reach the ideal frequency range of around 1 GHz that enables simultaneous temporal and spectral phonon sideband resolution close to the combined fundamental time-bandwidth limit.

cond-mat.mes-hall

Towards establishing formal verification and inductive code synthesis in the PLC domain

Nowadays, formal methods are used in various areas for the verification of programs or for code generation from models in order to increase the quality of software and to reduce costs. However, there are still fields in which formal methods have not been widely adopted, despite the large set of possible benefits offered. This is the case for the area of programmable logic controllers (PLC). This article aims to evaluate the potential of formal methods in the context of PLC development. For this purpose, the general concepts of formal methods are first introduced and then transferred to the PLC area, resulting in an engineering-oriented description of the technology that is based on common concepts from PLC development. Based on this description, PLC professionals with varying degrees of experience were interviewed for their perspective on the topic and to identify possible use cases within the PLC domain. The survey results indicate the technology's high potential in the PLC area, either as a tool to directly support the developer or as a key element within a model-based systems engineering toolchain. The evaluation of the survey results is performed with the aid of a demo application that communicates with the Totally Integrated Automation Portal from Siemens and generates programs via Fastsynth, a model-based open source code generator. Benchmarks based on an industry-related PLC project show satisfactory synthesis times and a successful integration into the workflow of a PLC developer.

cs.SE

Nonlinear quantum dot optomechanics

Wave mixing is an archetypical phenomenon in bosonic systems. In optomechanics, the bi-directional conversion between electromagnetic waves or photons at optical frequencies and elastic waves or phonons at radio frequencies is building on precisely this fundamental principle. Surface acoustic waves provide a versatile interconnect on a chip and, thus, enable the optomechanical control of remote systems. Here, we report on the coherent nonlinear three-wave mixing between the coherent fields of two radio frequency surface acoustic waves and optical laser photons via the dipole transition of a single quantum dot exciton. In the resolved sideband regime, we demonstrate fundamental acoustic analogues of sum and difference frequency generation between the two SAWs and employ phase matching to deterministically enhance or suppress individual sidebands. This bi-directional transfer between the acoustic and optical domains is described by theory which fully takes into account direct and virtual multi-phonon processes. Finally, we show that the precision of the wave mixing is limited by the frequency accuracy of modern radio frequency electronics.

quant-ph