935 research outputs found
Proceedings of SIRM 2023 - The 15th European Conference on Rotordynamics
It was our great honor and pleasure to host the SIRM Conference after 2003 and 2011 for the third time in Darmstadt. Rotordynamics covers a huge variety of different applications and challenges which are all in the scope of this conference. The conference was opened with a keynote lecture given by Rainer Nordmann, one of the three founders of SIRM “Schwingungen in rotierenden Maschinen”. In total 53 papers passed our strict review process and were presented. This impressively shows that rotordynamics is relevant as ever. These contributions cover a very wide spectrum of session topics: fluid bearings and seals; air foil bearings; magnetic bearings; rotor blade interaction; rotor fluid interactions; unbalance and balancing; vibrations in turbomachines; vibration control; instability; electrical machines; monitoring, identification and diagnosis; advanced numerical tools and nonlinearities as well as general rotordynamics. The international character of the conference has been significantly enhanced by the Scientific Board since the 14th SIRM resulting on one hand in an expanded Scientific Committee which meanwhile consists of 31 members from 13 different European countries and on the other hand in the new name “European Conference on Rotordynamics”. This new international profile has also been
emphasized by participants of the 15th SIRM coming from 17 different countries out of three continents. We experienced a vital discussion and dialogue between industry and academia at the conference where roughly one third of the papers were presented by industry and two thirds by academia being an excellent basis to follow a bidirectional transfer what we call xchange at Technical University of Darmstadt. At this point we also want to give our special thanks to the eleven industry sponsors for their great support of the conference. On behalf of the Darmstadt Local Committee I welcome you to read the papers of the 15th SIRM giving you further insight into the topics and presentations
AI: Limits and Prospects of Artificial Intelligence
The emergence of artificial intelligence has triggered enthusiasm and promise of boundless opportunities as much as uncertainty about its limits. The contributions to this volume explore the limits of AI, describe the necessary conditions for its functionality, reveal its attendant technical and social problems, and present some existing and potential solutions. At the same time, the contributors highlight the societal and attending economic hopes and fears, utopias and dystopias that are associated with the current and future development of artificial intelligence
Beam scanning by liquid-crystal biasing in a modified SIW structure
A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium
Electron Thermal Runaway in Atmospheric Electrified Gases: a microscopic approach
Thesis elaborated from 2018 to 2023 at the Instituto de AstrofĂsica de AndalucĂa under the supervision of Alejandro Luque (Granada, Spain) and Nikolai Lehtinen (Bergen, Norway). This thesis presents a new database of atmospheric electron-molecule collision cross sections which was published separately under the DOI :
With this new database and a new super-electron management algorithm which significantly enhances high-energy electron statistics at previously unresolved ratios, the thesis explores general facets of the electron thermal runaway process relevant to atmospheric discharges under various conditions of the temperature and gas composition as can be encountered in the wake and formation of discharge channels
Rethinking FPGA Architectures for Deep Neural Network applications
The prominence of machine learning-powered solutions instituted an unprecedented trend of integration into virtually all applications with a broad range of deployment constraints from tiny embedded systems to large-scale warehouse computing machines. While recent research confirms the edges of using contemporary FPGAs to deploy or accelerate machine learning applications, especially where the latency and energy consumption are strictly limited, their pre-machine learning optimised architectures remain a barrier to the overall efficiency and performance.
Realizing this shortcoming, this thesis demonstrates an architectural study aiming at solutions that enable hidden potentials in the FPGA technology, primarily for machine learning algorithms. Particularly, it shows how slight alterations to the state-of-the-art architectures could significantly enhance the FPGAs toward becoming more machine learning-friendly while maintaining the near-promised performance for the rest of the applications. Eventually, it presents a novel systematic approach to deriving new block architectures guided by designing limitations and machine learning algorithm characteristics through benchmarking.
First, through three modifications to Xilinx DSP48E2 blocks, an enhanced digital signal processing (DSP) block for important computations in embedded deep neural network (DNN) accelerators is described. Then, two tiers of modifications to FPGA logic cell architecture are explained that deliver a variety of performance and utilisation benefits with only minor area overheads. Eventually, with the goal of exploring this new design space in a methodical manner, a problem formulation involving computing nested loops over multiply-accumulate (MAC) operations is first proposed. A quantitative methodology for deriving efficient coarse-grained compute block architectures from benchmarks is then suggested together with a family of new embedded blocks, called MLBlocks
Security and Privacy for Modern Wireless Communication Systems
The aim of this reprint focuses on the latest protocol research, software/hardware development and implementation, and system architecture design in addressing emerging security and privacy issues for modern wireless communication networks. Relevant topics include, but are not limited to, the following: deep-learning-based security and privacy design; covert communications; information-theoretical foundations for advanced security and privacy techniques; lightweight cryptography for power constrained networks; physical layer key generation; prototypes and testbeds for security and privacy solutions; encryption and decryption algorithm for low-latency constrained networks; security protocols for modern wireless communication networks; network intrusion detection; physical layer design with security consideration; anonymity in data transmission; vulnerabilities in security and privacy in modern wireless communication networks; challenges of security and privacy in node–edge–cloud computation; security and privacy design for low-power wide-area IoT networks; security and privacy design for vehicle networks; security and privacy design for underwater communications networks
Athermal Phonon Sensors in Searches for Light Dark Matter
In recent years, theoretical and experimental interest in dark matter (DM)
candidates have shifted focus from primarily Weakly-Interacting Massive
Particles (WIMPs) to an entire suite of candidates with masses from the
zeV-scale to the PeV-scale to 30 solar masses. One particular recent
development has been searches for light dark matter (LDM), which is typically
defined as candidates with masses in the range of keV to GeV. In searches for
LDM, eV-scale and below detector thresholds are needed to detect the small
amount of kinetic energy that is imparted to nuclei in a recoil. One such
detector technology that can be applied to LDM searches is that of
Transition-Edge Sensors (TESs). Operated at cryogenic temperatures, these
sensors can achieve the required thresholds, depending on the optimization of
the design.
In this thesis, I will motivate the evidence for DM and the various DM
candidates beyond the WIMP. I will then detail the basics of TES
characterization, expand and apply the concepts to an athermal phonon
sensor--based Cryogenic PhotoDetector (CPD), and use this detector to carry out
a search for LDM at the surface. The resulting exclusion analysis provides the
most stringent limits in DM-nucleon scattering cross section (comparing to
contemporary searches) for a cryogenic detector for masses from 93 to 140 MeV,
showing the promise of athermal phonon sensors in future LDM searches.
Furthermore, unknown excess background signals are observed in this LDM search,
for which I rule out various possible sources and motivate stress-related
microfractures as an intriguing explanation. Finally, I will shortly discuss
the outlook of future searches for LDM for various detection channels beyond
nuclear recoils.Comment: 243 pages, Ph.D. Thesis in Physics at UC Berkele
LIPIcs, Volume 261, ICALP 2023, Complete Volume
LIPIcs, Volume 261, ICALP 2023, Complete Volum
TIFF: Gyrofluid Turbulence in Full-f and Full-k
A model and code (TIFF) for isothermal gyrofluid computation of
quasi-two-dimensional interchange and drift wave turbulence in magnetized
plasmas with arbitrary fluctuation amplitudes (full-f) and arbitrary
polarization wavelengths (full-k) is introduced. The model reduces to the
paradigmatic Hasegawa-Wakatani model in the limits of small turbulence
amplitudes (delta-f), cold ions (without finite Larmor radius effects), and
homogeneous magnetic field. Several solvers are compared for the generalized
Poisson problem, that is intrinsic to the full-f gyrofluid (and gyrokinetic)
polarization equation, and a novel implementation based on a dynamically
corrected Fourier method is proposed. The code serves as a reference case for
further development of three-dimensional full-f full-k models and solvers, and
for fundamental exploration of large amplitude turbulence in the edge of
magnetized plasmas
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