bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multi‐operating characteristic analysis and loss optimization of novel large capacity high‐speed permanent magnet generator
Authors: Ye Bitian , Xie Ying , Cai Wei , Jin Huiyong , Sun Yutian , Bai Jing 
Published: November 2024

AbstractRecently, the development trend of large capacity generator has gradually shifted from electrical excitation generator to permanent magnet generator (PMG). As a result, the large capacity high‐speed permanent magnet generator (HSPMG) with high power density and high efficiency have received widespread attention. This paper aims to analyse the loss optimization of novel large capacity HSPMG under multi‐operating conditions. In terms of the parameter requirements, a 2.5 MW and 7000 rpm HSPMG is designed. To verify the accuracy of simulation model and the rationality of generator design, the output characteristics of large capacity HSPMG which has been combined with prototype experimental data are calculated under both no‐load and load conditions. Based on the load power characteristics of large capacity HSPMG, the optimization range of the magnetization angle under multi‐operating conditions is explored. By analysing the no‐load back electromotive force (EMF) and loss characteristics of large capacity HSPMG, the optimal magnetization angle that corresponds to the minimum loss under three conditions is obtained. The correctness of the analysis and optimization method is verified by comparing the loss distribution and electromagnetic results before and after the optimization. The research results provide a reference for the multi‐operating characteristics analysis and loss optimization of large capacity HSPMG.
A generalized method of power oscillation characteristic analysis for multi‐VSC grid‐connected system
Authors: Xu Yonghai , Qin Benshuang , Jia Jiaoxin , Shan Aobo , Chen Yidan , Yingxin Wang 
Published: November 2024

AbstractThe grid‐connection of high‐permeability new energy through voltage‐source converters (VSCs) brings new oscillation risks to the power system, which seriously threatens the stable operation of the system. Therefore, an evaluating method based on modal analysis is proposed to investigate the power oscillation characteristics in a multi‐VSC grid‐connected system. Initially, based on the analogy method, the output admittance model of voltage‐source controlled VSCs (VC‐VSCs) and current‐source controlled VSCs (CC‐VSCs) is established. Subsequently, the output admittance model of a multi‐VSC grid‐connected system is constructed. Then, the modal analysis method is introduced to investigate the power oscillation characteristics of VC‐VSCs and CC‐VSCs, and the influence factors of power oscillation and its variation law are analysed. Next, a sensitivity analysis is also employed, which helps to identify the origin of each oscillation mode and determine the contribution of each component to the power oscillation. Finally, simulation and experiment are carried out to verify the effectiveness of the above analysis method.
Piezoelectric deicing system for aeronautics: Extensional mode actuator and power supply
Authors: Jomaa Modar , Lévy Pierre‐Etienne , Vasic Dejan , Costa François , Ali Marwan 
Published: November 2024

AbstractRecent research shows a growing interest in low‐power avionic deicing systems, in particular, those based on piezoelectric actuators for their energy efficiency. The system generates micrometric vibrations in the structure to delaminate and break the ice with a low power requirement. However, designing the power supply and its control for driving piezoelectric actuators is challenging due to their distinctive capacitive behavior at most frequencies, especially in deicing applications requiring high operational frequency. This contribution addresses the two cross‐dependent parts of the deicing system, that is the piezoelectric actuator designed for breaking any kind of ice on a large area and its power supply made of a 1 kW/200 V/2 MHz auxiliary resonant commutated pole inverter (ARCPI). The choice of this converter is based on the specific constraints of the application, such as varying the operating frequency with the actuator working conditions, the long cables and necessary insulation between the actuator and its supply, the soft‐switching operation and reactive energy balancing for a good efficiency. Based on these criteria, the converter was developed and realized in the laboratory. Deicing tests confirmed effective operation with a power input density of 122 mW/cm2, using nine piezoelectric patches per dm2.
Characterisation and synchronisation of a netted software defined radio radar
Authors: Valdes Crespi Ferran , Slavov Angel , Weiß Matthias , Knott Peter , O’Hagan Daniel 
Published: November 2024

AbstractThe present work intends to characterise the combination of two netted software defined radios (SDR) and different radio frequency (RF) front‐ends installed in them, together with a two‐stratum time dissemination and synchronisation system. A modified implementation of the Network Time Protocol is used as coarse event synchronisation for either SDR back‐end. The White rabbit light embedded node implementation of the commonly known white rabbit synchronisation system (IEEE 1588 PTP‐2019) or arbitrary wave form generators are used as fine time dissemination system for either SDR. The resulting netted transceiver system is intended to compose a demonstrator for proof‐of‐concept experiments. The findings presented in this article show that the chosen combination of hardware and software is suitable for radar applications operating within L‐, S‐ and C‐bands. A channel coherency throughout the network with a relative modified Allan deviation of less than 80 fs for averaging intervals of 1 s, a phase noise better than −118 dBc/Hz at 10 Hz frequency offset and a fractional frequency lower than was measured. Within a single transceiver node, a fractional frequency lower than and phase noise of −124 dBc/Hz at 10 Hz frequency offset were measured as well. Multistatic radar systems exploit wide spatial diversity to enhance target detection and tracking, albeit with increased complexity when compared to a monostatic configuration. To exploit these benefits, all participating transceiver nodes within the netted radar need to synchronise to a common time base . The achieved synchronisation level increases the accuracy with which the chain of timed events at the transmitter and at the receiver side occur, intending to maximise the signal‐to‐noise ratio available at the receiver. The Universal software radio peripheral model X310 with two different daughterboard models as RF front‐end was used as SDR on either radar node. A network combining data and synchronisation purposes allowed the radar nodes under test to operate synchronously. The two‐stratum synchronisation system used glass fibres between 2 m and 5 km of length or coaxial cables with 2 m in length for network traffic, time and frequency dissemination purposes. The multiple RF front‐ends were stimulated by means of arbitrary waveform generators with calibrated traceability. Up‐chirp and sinusoid waveforms were used as stimuli for measuring the offset of either channel with regards of to ultimately estimate the achievable coherency limits of the system under test. Both analogue and digital evaluation methods were considered.
Short‐term energy forecasting using deep neural networks: Prospects and challenges
Authors: Tsegaye Shewit , Sanjeevikumar Padmanaban , Tjernberg Lina Bertling , Fante Kinde Anlay 
Published: November 2024

AbstractThis study presents an in‐depth overview of deep neural networks (DNN) and their hybrid applications for short‐term energy forecasting (STEF). It examines DNN‐based STEF from three perspectives: basics, challenges, and prospects. The study compares recent literature using metrics like mean absolute error (MAE), mean average percentage error (MAPE), and root mean square error (RMSE). Findings indicate that combining automated data‐driven models with enhanced DNNs effectively addresses forecasting challenges. It also highlights the role of DNNs in integrating energy prosumers, renewable energy systems, microgrids, big data, and smart grids to improve STEF.
Searching for similarities in the accretion flow of Seyfert 1 galaxies and cataclysmic variables based on the flare profiles of IRAS 13224–3809, 1H 0707–495, Mrk 766, and MV Lyr
Authors: Dobrotka A. , Negoro H. , Bezák P. 
Published: November 2024

Aims. We studied the fast variability of three selected active galactic nuclei (AGNs), IRAS 13224−3809, 1H 0707−495, and Mrk 766, and the cataclysmic variable MV Lyr, which were observed by the XMM-Newton and Kepler spacecrafts, respectively. Our goal is to search for the common origin of the variability and to test the so-called sandwich model, in which a geometrically thick corona surrounds a geometrically thin disc.
Context. We studied the substructures of the averaged flare profiles. The flare profile method identifies individual flares in the light curve, and averages them. The direct fitting of the profile substructures identified individual characteristic frequencies that are seen in standard power density spectra (PDS) as a break frequency or quasi-periodic oscillation. The credibility of the flare profile substructures is demonstrated by comparison with the autocorrelation function.
Results. We found that the flare profiles of AGNs are similar to those of a cataclysmic variable in the low state. We explain this as a consequence of a truncated inner disc in a sandwich model. The same scenario is also able to explain the characteristic break frequencies in X-ray PDS, which are not seen in the optical. We also searched for substructures in the flare profile of IRAS 13224−3809. In addition to a permanently present main flare, we found that a transient side-lobe appears before the main flare and is only seen in a high-flux period. The complex flare profile of this AGN suggests that an additional source of X-rays appears during the high-flux period. We propose a scenario in which an accretion flow fluctuation enters the sandwich corona and propagates further to some very central part of the accretion disc.
High stability of charged particle clusters in protoplanetary disks
Authors: Schwaak J. , Führer F. , Wolf D. E. , Posorski L. , Brendel L. , Teiser J. , Wurm G. 
Published: November 2024

Context. The initial particle growth in protoplanetary disks is limited by a bouncing barrier at submillimeter wavelengths. Bouncing leads to tribocharging and the electrostatic attraction of tribocharged aggregates may eventually draw them into large clusters. A charge- mediated growth phase allows for the formation of larger entities, namely, clusters of aggregates that are more prone to further particle concentrations, such as the streaming instability.
Aims. We aim to quantify the strength of the electrostatic forces.
Methods. In laboratory experiments, we used an acoustic trap to levitate small aggregates of tribocharged submm grains. These aggregates spin up within the trap until they lose grains. Thus, we used the centrifugal force as a measure of the local force.
Results. Grains are regularly bound strongly to their neighbors. In comparison, the force at ejection can be stronger than the attractive scattering forces of the trap and can therefore be several orders of magnitude larger than expected. We note that these forces are long- ranging, compared to van der Waals forces. Thus, charged aggregates are much more stable than uncharged ones.
Conclusions. Particle aggregates in disks might grow to centimeter clusters or larger as tribocharging increases the effective binding forces. This allows for hydrodynamic concentration and planetesimal formation to eventually take place throughout a wide part of the disk.
The MeerKAT view on Galactic supernova remnants
Authors: Loru S. , Ingallinera A. , Umana G. , Bordiu C. , Buemi C. , Bufano F. , Cavallaro F. , Leto P. , Riggi S. , Trigilio C. , Thompson M. A. , Cotton W. D. , Goedhart S. , Anderson L. D. , Chibueze J. O. 
Published: November 2024

Context. The integrated radio spectrum of supernova remnants (SNRs) and the spatial variation of the spectral indices across these extended sources are powerful tools for studying the shocks and particle acceleration processes occurring in different SNR regions. Characterization of these processes requires sensitive flux density measurements and high-resolution images, which are not always available due to observing difficulties.
Aims. We want to show the potentiality of the high-resolution SARAO MeerKAT legacy Galactic Plane Survey (SMGPS) images regarding the morphological and spectral characterization of 29 known galactic SNRs.
Methods. We used the SMGPS data at 1.284 GHz coupled with data from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey (0.072–0.231 GHz) to characterize the integrated spectrum of each source and search for spatial spectral variation through analysis of sensitive spectral index maps.
Results. We were able to redefine the exact morphology of four SNRs (G024.7–00.6, G051.4+00.7, G348.7+0.3, and G351.9+00.1), distinguishing them from unrelated sources or identifying new emission regions associated with them and never observed before. In many other cases, we identified in the SMGPS images several H II regions overlaid with the remnants, and we were able to estimate their spectral contribution through inspection of the spatial variation of the spectral indices across the remnants. The integrated spectral indices show a more uniform distribution with respect to what is obtained by considering the values reported in the literature.
Conclusions. We show that new sensitive and high-resolution data are crucial to firmly constraining both the integrated and spatially resolved spectrum of SNRs, especially for the less studied objects of the southern hemisphere. The comparison of our SMGPS-GLEAM spectral index maps with IR, molecular, and γ-ray images allowed us to investigate the nature of the peculiar remnant regions.
TODDLERS: A new UV-millimeter emission library for star-forming regions
Authors: Kapoor Anand Utsav , Baes Maarten , van der Wel Arjen , Gebek Andrea , Camps Peter , Smith Aaron , Boquien Médéric , Andreadis Nick , Vicens Sebastien 
Published: November 2024

Context. The current generation galaxy formation simulations often approximate star formation, making it necessary to use models of star-forming regions to produce observables from such simulations. In the first paper of this series, we introduced TODDLERS, a physically motivated, time-resolved model for UV–millimeter (mm) emission from star-forming regions, implemented within the radiative transfer code SKIRT. In this work, we use the SKIRT-TODDLERS pipeline to produce synthetic observations.
Aims. We aim to demonstrate the potential of TODDLERS model through observables and quantities pertaining to star-formation. An additional goal is to compare the results obtained using TODDLERS with the existing star-forming regions model in SKIRT.
Methods. We calculated broadband and line emission maps for the 30 Milky Way-like galaxies of the Auriga zoom simulation suite at a redshift of zero. Analyzing far-ultraviolet (FUV) and infrared (IR) broadband data, we calculated kiloparsec (kpc)-resolved IR correction factors, kIR, which allowed us to quantify the ratio of FUV luminosity absorbed by dust to reprocessed IR luminosity. Furthermore, we used the IR maps to calculate the kpc-scale mid-infrared (MIR) colors (8 μm/24 μm) and far-infrared (FIR) colors (70 μm/500 μm) of the Auriga galaxies. We used Hα and Hβ line maps to study the Balmer decrement and dust correction. We verified the fidelity of our model’s FIR fine structure lines as star formation rate (SFR) indicators.
Results. The integrated UV-mm spectral energy distributions (SEDs) exhibit higher FUV and near-ultraviolet (NUV) attenuation and lower 24 μm emission compared to the existing star-forming regions model in SKIRT, alleviating tensions with observations reported in earlier studies. The light-weighted mean kIR increases with aperture and inclination, while its correlation with kpc-resolved specific star-formation rate (sSFR) is weaker than literature values from resolved SED fitting, potentially due to inaccuracies in local energy balance representation. The kpc-scale MIR-FIR colors show an excellent agreement with local observational data, with anti-correlation degree varying by galaxy morphology. We find that the Balmer decrement effectively corrects for dust, with the attenuation law varying with dust amount. The Hα emission attenuation levels in our models are comparable to those observed in the high-density regions of state-of-the-art radiation hydrodynamical simulations. The FIR fine-structure line emission-based luminosity-SFR relations are consistent with global observational relations, with the [C II] line displaying the best agreement.
Position Paper of the German Society for Interventional Radiology and Minimally Invasive Therapy (DeGIR) and the German Roentgen Society (DRG) on Structural and Professional Requirements in Interventional Oncology
Authors: Isfort Peter , Sommer Christof M , Bruners Philipp , Maiwald Bettina , Kühn Jens-Peter , Radosa Christoph Georg , Kloeckner Roman , Freyhardt Patrick , Franke Mareike , Moche Michael , Hoffmann Ralf-Thorsten , Nikolaou Konstantin , Mahnken Andreas H. , Katoh Marcus 
Published: November 2024

AbstractInterventional oncology (IO) employs various techniques to enable minimally invasive, image-guided treatment of tumor diseases with both curative and palliative goals. Additionally, it significantly contributes to managing tumor-related and perioperative complications, offering diverse supportive procedures for patients at all stages of their diseases. The execution of IO procedures places unique demands on the equipment, personnel, and structural organization of radiological clinics, necessitating specific expertise from interventional radiologists.This position paper aims to comprehensively outline the multifaceted aspects of IO and discuss the requisite criteria for hospitals, radiological clinics, and interventional radiologists (IRs). Furthermore, it underscores overarching considerations of quality assurance that clinics and professional societies should prioritize.The requirements for hospitals, radiological clinics, and IRs are varied and demand not only a high level of proficiency in performing IO procedures but also in-depth knowledge of the differential therapy for various tumor diseases. This expertise is essential for effectively serving as clinical partners in the interdisciplinary treatment of oncologic patients. Additionally, a thorough understanding and safe handling of ionizing radiation technologies, along with proficiency in radiation protection methods, which are fundamental aspects of radiological specialist training, is crucial for ensuring the safety of IO procedures for both patients and staff. The Deutsche Gesellschaft für Interventionelle Radiologie und minimal-invasive Therapie (DeGIR) and the Cardiovascular and Interventional Radiological Society of Europe (CIRSE) have long-established dedicated quality management programs, accrediting radiology clinics and certifying IRs. These initiatives aim to uphold the highest standards of care and meet the quality expectations set by politics in healthcare system, particularly in the realm of interventional radiology.
Machine-Learning Applications in Thrombosis and Hemostasis
Authors: Nilius Henning , Nagler Michael 
Published: November 2024

AbstractThe use of machine-learning (ML) algorithms in medicine has sparked a heated discussion. It is considered one of the most disruptive general-purpose technologies in decades. It has already permeated many areas of our daily lives and produced applications that we can no longer do without, such as navigation apps or translation software. However, many people are still unsure if ML algorithms should be used in medicine in their current form. Doctors are doubtful to what extent they can trust the predictions of algorithms. Shortcomings in development and unclear regulatory oversight can lead to bias, inequality, applicability concerns, and nontransparent assessments. Past mistakes, however, have led to a better understanding of what is needed to develop effective models for clinical use. Physicians and clinical researchers must participate in all development phases and understand their pitfalls. In this review, we explain the basic concepts of ML, present examples in the field of thrombosis and hemostasis, discuss common pitfalls, and present a methodological framework that can be used to develop effective algorithms.
Large language models (LLMs) in radiology exams for medical students: Performance and consequences
Authors: Gotta Jennifer , Le Hong Quang Anh , Koch Vitali , Gruenewald Leon D. , Geyer Tobias , Martin Simon S. , Scholtz Jan-Erik , Booz Christian , Pinto Dos Santos Daniel , Mahmoudi Scherwin , Eichler Katrin , Gruber-Rouh Tatjana , Hammerstingl Renate , Biciusca Teodora , Juergens Lisa Joy , Höhne Elena , Mader Christoph , Vogl Thomas J. , Reschke Philipp 
Published: November 2024

AbstractThe evolving field of medical education is being shaped by technological advancements, including the integration of Large Language Models (LLMs) like ChatGPT. These models could be invaluable resources for medical students, by simplifying complex concepts and enhancing interactive learning by providing personalized support. LLMs have shown impressive performance in professional examinations, even without specific domain training, making them particularly relevant in the medical field. This study aims to assess the performance of LLMs in radiology examinations for medical students, thereby shedding light on their current capabilities and implications.This study was conducted using 151 multiple-choice questions, which were used for radiology exams for medical students. The questions were categorized by type and topic and were then processed using OpenAIʼs GPT-3.5 and GPT- 4 via their API, or manually put into Perplexity AI with GPT-3.5 and Bing. LLM performance was evaluated overall, by question type and by topic.GPT-3.5 achieved a 67.6% overall accuracy on all 151 questions, while GPT-4 outperformed it significantly with an 88.1% overall accuracy (p<0.001). GPT-4 demonstrated superior performance in both lower-order and higher-order questions compared to GPT-3.5, Perplexity AI, and medical students, with GPT-4 particularly excelling in higher-order questions. All GPT models would have successfully passed the radiology exam for medical students at our university.In conclusion, our study highlights the potential of LLMs as accessible knowledge resources for medical students. GPT-4 performed well on lower-order as well as higher-order questions, making ChatGPT-4 a potentially very useful tool for reviewing radiology exam questions. Radiologists should be aware of ChatGPTʼs limitations, including its tendency to confidently provide incorrect responses.