bluuebunny/crossref_metadata_2025 huggingface dataset:
Intelligent control of the power generation system using DSPACE
Authors: Hamid Chojaa , Aziz Derouich , Zamzoum Othmane , El Idrissi Abderrahman , Zawbaa Hossam M. , Zeinoddini‐Meymand Hamed , Kamel Salah
Published: May 2024

Wind power systems (WPs) are complex non‐linear systems with varying parameters affected by environmental changes, including wind speed fluctuations. Extracting maximum power from WPs poses a significant challenge due to these factors. Direct power control (DPC) is a highly effective technique known for its simplicity and ease of implementation. However, it suffers from power ripples caused by the use of hysteresis comparators and switching tables that operate at variable frequencies. To address this issue, this paper presents the robust neural controller (NC) based on DPC, which replaces the switching tables. The Double‐Fed Induction Generator (DFIG) is the chosen generator for the studied WP system due to its advantageous features. The NC‐DPC effectively regulates the exchange of active and reactive powers between the DFIG and the system, maximizing power extraction from the WP system while reducing Total Harmonic Distortion and enhancing overall system quality. The effectiveness of the NC‐DPC is evaluated through MATLAB simulations and further supported by experimental data obtained using the Real‐Time Interface of the dSPACE‐DS1104 Controller card.
Optimized coil and current flow designs for wireless charging containers with improved even magnetic flux density distribution
Authors: Liang Rui , Wang Kaiyuan , Sun Zhen , Zeng Junming , Liu Siyang , Wu Huihuan , Yang Yun
Published: May 2024

This paper introduces three different shapes of wireless charging containers (i.e. quadrangular prism, octagonal prism, and hexagonal prism) and presents optimal current flow designs for the coils to enhance the uniformity of magnetic flux distribution inside the containers. Additionally, the concept of folded coil design is introduced to further improve the even distribution of magnetic flux density within the containers. The performance of these designs is evaluated through simulations and practical experiments.
Physical insight into turn‐on transient of silicon carbide gate turn‐off thyristor
Authors: Liu Hangzhi , Liang Shiwei , Zhou Yuming , Wang Jun
Published: May 2024

Silicon Carbide (SiC) Gate Turn‐off (GTO) thyristor is regarded as a promising option for pulsed power applications; however, the formation of high di/dt has been constrained by the slow current rise transient phase and the turn‐on current heterogeneity over the chip device. In this paper, a practical integrated multi‐cell simulation is performed to physically characterize the turn‐on transient of SiC GTO thyristor. Through examining electrical coupling between adjacent cells caused by both parasitics of electrode metallization and carrier travelling via SiC, the current distributions are observed, and the carrier transport dynamics are analyzed in detail. Furthermore, physical mechanisms dominating the current heterogeneity among multi‐cells are discovered in depth. It is revealed that the current heterogeneity during the turn‐on transient is primarily resulted from the Gate signal delay caused by the Gate Runner metallization, and the lateral interaction from adjacent semiconductor regions adds to this inhomogeneity; however, this situation can be improved once the electrical distance between each Anode contact and the Anode electrode gets lowered. Design method for turn‐on performance improvement is also proposed accordingly. Besides, based on the analysis conducted on the multi‐cell simulation results, the possible reason of the extremely slow current rise transient phase is speculated and experimentally verified. The improvement in the comprehension of SiC GTO's turn‐on transient, which cannot be obtained from the traditional investigation from the viewpoint of one elementary cell, will provide guiding principles helping in directing future efforts to advance the improvement of device design technology.
Experimental investigation of tool feed rate and machining strategy on surface roughness in flat end milling of Nickel-Iron alloy Supra50
Authors: Ftoutou Ezzeddine , Ben Said Mihed , Frih Ahmed Seifallah , Ben Khalifa Ated , Trigui Moez
Published: May 2024

The Nickel-Iron alloy Supra50 is one of the commonly used materials for manufacturing aeronautical parts and is resistant to excessive thermal stress. Due to its low coefficient of expansion, this material can guarantee dimensional stability at high temperatures while also offering mechanical characteristics like those of stainless steel. However, several works in the literature demonstrate that the Nickel-Iron alloy Supra50 has low machinability due to low thermal conductivity and work hardening. These main qualities, with its magnetic characteristics, qualified it for the manufacture of components for solenoid valves in aircraft. Despite its performance, obtaining Supra50 parts by machining presents difficulties. Indeed, faced with tight dimensional and geometric tolerances, manufacturers must invest in means and methods that converge to an agreement between cost and quality that ensures the efficiency of the machining process. This research work aims to analyze the effect of machining strategies and the tool feed rate on surface roughness by using an experimental approach in a Fe-Ni-based alloy-Supra50 surfacing operation with a flat end-mill tool. This study addresses a gap in the literature, focusing on the unique challenges posed by Supra 50 machining. It was demonstrated that the feed rate strongly affects surface roughness. In other hand, it was demonstrated that the machining strategy sweep gives the minimum of arithmetic mean height of the surface (Sa), compared to other analyzed machining strategies, such as mono-directional sweep and spiral sweep. All experimental results were demonstrated in sequence with other literature works on Fe-Ni-based alloy machining.
Seeds and plant protection substances for French organic oilseed crops: what are the challenges for tomorrow?
Authors: Le Gall Cécile , Hidrot David , Girolami Pauline , Marchand Patrice
Published: May 2024

Organic production systems rely on different combinations of agronomic levers to ensure their sustainability, notably seeds and crop protection products. These inputs were mostly developed for conventional farming, which is the main market, and then evaluated under organic conditions. However, the growth of organic farming raises the question of producing inputs more specifically designed for this type of production, with its technical constraints, concepts and ethics. Recently, changes to European regulations on organic farming have opened up new perspectives, particularly in terms of varietal selection and evaluation, with introduction of the notions of “organic variety” and “organic heterogeneous material”. These two notions challenge and question the concept of variety, as well as the classic methods for evaluating their performance. With regard to crop protection products, a number of products can now be used on oilseed crops, including basic substances, low-risk substances and biocontrol agents but, the list remains limited, particularly for sunflower and soybean. However, new innovations are emerging, particularly in biocontrol agents, which augur new possibilities for controlling diseases and pests for which no solution is currently available. It is therefore necessary to support research in order to provide rapid solutions, and also to ensure that regulations evolve to promote their integration and availability to farmers. The use of inputs (seeds and plant protection products) in organic farming is governed by a number of European regulations, which are sometimes difficult to harmonize.
L’enseignement de la médecine intégrative en France : état des lieux et perspectives
Authors: Berna Fabrice , Verneuil Laurence , Paille François , Nizard Julien
Published: May 2024

Contexte : Le recours aux pratiques de soins non conventionnelles concerne une large proportion de la population en France, en particulier les patients ayant des maladies chroniques. Certaines sont utilisées par des professionnels de santé et sont intégrées aux soins conventionnels, par exemple dans des services hospitaliers de médecine intégrative. Sensibiliser les étudiants en médecine à ces approches est important pour mieux accueillir les choix thérapeutiques des patients et savoir les conseiller. La question de l’implication de l’université dans une formation à la médecine intégrative et certaines pratiques non conventionnelles est cependant débattue en France et ne fait pas consensus. Objectif : Après une clarification des concepts principaux mobilisés, cet article dresse un état des lieux de l’enseignement universitaire des pratiques de soins non conventionnelles et de la médecine intégrative en France. Il propose une analyse succincte de la structuration de la médecine intégrative et de son enseignement en Suisse et en Allemagne. Résultats : Notre analyse permet d’identifier certaines insuffisances dans l’offre de formation en France. Nous argumentons qu’un des aspects de la stratégie de réduction des risques appliquée à ces pratiques passe par une implication de l’université dans l’enseignement de la médecine intégrative. Le projet d’une formation spécialisée transversale en médecine intégrative est proposé comme une réponse possible. Conclusion : La structuration de la médecine intégrative et de son enseignement en France permettrait d’offrir aux patients un accès sécurisé à certaines pratiques pertinentes et la France de rejoindre les nombreux pays qui la devancent dans ce domaine.
Der neonatale Fc-Rezeptor: Biologische Grundlagen und Potenzial der
therapeutischen Blockade in der Behandlung immunhämatologischer
Erkrankungen
Authors: Wienzek-Lischka Sandra , Bein Gregor
Published: May 2024

Durch den Transport von mütterlichen IgG-Antikörpern in die Zirkulation des Fetus
erhalten die Nachkommen den humoralen „Nestschutz“ bzw. die mütterliche
„Leihimmunität“. Der transplazentare Transport von IgG-Antikörpern erfolgt in
einem komplexen Prozess, an dem der neonatale Rezeptor für das kristallisierbare
Fragment von IgG-Molekülen (Fragment cristallizable receptor neonatal, FcRn)
essenziell beteiligt ist. FcRn ist im adulten Organismus ubiquitär exprimiert,
reguliert die IgG- und Albumin-Homöostase, sowie die angeborene und adaptive
Immunität gegen IgG-Immunkomplexe und ist damit an der Abwehr infektiöser
Erkrankungen und der Anti-Tumor-Immunität beteiligt. Therapeutische
FcRn-Antagonisten blockieren das Recycling von IgG-Molekülen und führen zu einer
Absenkung der IgG-Serumspiegel. Im Rahmen einer Schwangerschaft blockieren
therapeutische FcRn-Antagonisten den transplazentaren IgG-Transport. Die
vorliegende Übersichtsarbeit soll den aktuellen Stand der potenziellen Anwendung
von FcRn-Antagonisten bei immunhämatologischen Erkrankungen durch Autoantikörper
sowie im Rahmen von Erkrankungen des Fetus und Neugeborenen durch mütterliche
Alloantikörper darstellen.
Strategien zur Versorgung von RhD-negativen Patienten mit
RhD-positiven Erythrozytenkonzentraten
Authors: Flommersfeld Sabine , Ertl Birgit
Published: May 2024

Die Versorgung von RhD-negativen Patienten stellt eine zunehmende Herausforderung
für nahezu alle transfundierenden Einrichtungen in Deutschland dar, verschärft
durch den bundesweiten Rückgang der Spendezahlen von ca. 10% gegenüber den
Spendezahlen vor der Coronapandemie. In dem Praxistipp wird sowohl auf die
Risikoevaluierung einer Immunisierung gegen das RhD-Merkmal eingegangen als auch
auf die verschiedenen Versorgungsstrategien zum einen bei unbekannten Patienten
in der Notfallversorgung, als auch bei RhD-negativen Patienten mit semielektivem
oder chronischem Transfusionsbedarf. Ferner werden die internationalen
Leitlinien in Bezug auf die Umstellungspraxis vorgestellt und verglichen.
Nachweis thrombozytärer Antikörper – aktueller Stand
Authors: Kiefel Volker
Published: May 2024

Thrombozyten spielen eine besondere Rolle bei der Blutstillung. Viele Ursachen
können die Leistungsfähigkeit des thrombozytären Systems beeinträchtigen, vor
allem Zustände mit einer verminderten Zahl von Thrombozyten. Antikörper gegen
Thrombozyten sind für einen Teil der Fälle von Thrombozytopenie verantwortlich,
sie können darüber hinaus die Wirksamkeit von Thrombozytentransfusionen
beeinträchtigen. Daher spielen Methoden zum Nachweis thrombozytärer Antikörper
bei der Diagnose und der Behandlung von thrombozytopenischen Zuständen eine
Rolle. Relativ hohe Kosten und Aufwand erfordern eine fachlich gut begründete
Indikationsstellung bei Kenntnis des klinischen Hintergrunds.
Hautklinik am DRK-Krankenhaus Chemnitz-Rabenstein – Vergangenheit, Gegenwart, Zukunft
Authors: Kaatz Martin , Ziller Fabian , Mlynek Agnieszka , Meinig Robert , Höpner Jörg , Löbig Tina , Fischer-Vulpe Konstantin , Ettler Jiri
Published: May 2024

Die Hautklinik am DRK-Krankenhaus Chemnitz-Rabenstein verfügt als Schwerpunktklinik für den Bereich Dermatologie und Allergologie über ein vollständiges Spektrum des Fachgebiets und versorgt nicht nur das Stadtgebiet Chemnitz, sondern auch weite Teile des Umlands bis in das Erzgebirge hinein.
20 Jahre Arbeitsgemeinschaft für Geschichte der Dermatologie und Venerologie in der Deutschen Dermatologischen Gesellschaft e. V. (AGDV)
Authors: Gregersen Deborah Maria , Lorenz Martin , Geiges Michael Lukas , Löser Christoph R.
Published: May 2024

Das Interesse an der eigenen Fachgeschichte und das Bewusstsein einer identitätsstiftenden Wirkung der Auseinandersetzung mit der Geschichte führten zur Gründung der AGDV. In regelmäßigen Arbeitstreffen und Sitzungen entstand eine Plattform für wissenschaftlichen Austausch und persönliche Projekte, die sich mit der Fachgeschichte beschäftigen. Dies ist ein Rück- und Ausblick über die 20-jährige Vereinsgeschichte.
Komplexe Bewegungskontrolle der HWS
Authors: Luomajoki Hannu , Ernst Markus
Published: May 2024

Liebe Leserinnen und Leser,

Bewegungskontrollproblematiken zählen zur Untergruppe unspezifischer Rückenschmerzen
oder besser gesagt zu der Gruppe von Rückenschmerzen, denen keine spezifische
strukturelle Ursache zugeordnet werden kann. Bisher wurden zuverlässige Tests dieser
Problematiken sowie wirksame Übungen zur Bewegungskontrolle im unteren Rückenbereich
veröffentlicht 1. Dazu zählen mehrere
randomisierte Studien sowie eine Meta-Analyse 2.
Die amerikanische Leitlinie für untere Rückenschmerzen empfiehlt
Bewegungskontrollübungen, wenn ein*e Patient*in dieser Untergruppe zugeordnet werden
kann 3.
Fallbeispiel: Bewegungskontrollstörung der
Halswirbelsäule
Authors: Luomajoki Hannu , Elsig Simone
Published: May 2024

Eine Patientin stellt sich mit Nackenschmerzen in der Physiotherapie vor. Die
Schlüsselfaktoren aus subjektivem und physischem Befund deuten auf ein
Bewegungskontrolldefizit hin. Eine schlüssige und für die Patientin logische
Erklärung ihres Problems und die unmittelbare Wirksamkeit der Übungen sind
ausschlaggebend für den Erfolg der Therapie.
Die operative Versorgung einer bimalleolären OSG-Fraktur – Tipps und Tricks
Authors: Mayr Jakob , Schramm Simon , Renner Nina , Perl Mario , Palm Hans-Georg
Published: May 2024

Die obere Sprunggelenksfraktur als häufigste Fraktur der unteren Extremitäten, verursacht vor allem durch Pro- und Supinationstraumata, stellt junge Operateure im Fach der O&U immer wieder vor spezielle Herausforderungen. Nicht zuletzt aufgrund des fragilen Weichteilmantels rund um das Sprunggelenk, auch aufgrund der anatomischen Gegebenheiten im Bereich des oberen Sprunggelenks und der postoperativen biomechanischen Belastungen bedarf es operativer Erfahrung, um gute operative Ergebnisse zu erzielen. Im folgenden Video werden die wichtigsten Schritte sowie Tipps und Tricks der operativen Versorgung einer Bimalleolarfraktur aufgegriffen und erklärt. Ziel des Lehrvideos ist es, die wichtigsten Schritte der Operation zu vermitteln und so den jungen Kollegen der O&U für ihren klinischen Alltag nahezubringen.
Fertility and Pregnancy after Bariatric Surgery: Challenges and Solutions
Authors: Mina Angeliki , Asraiti Amna , Abdelgadir Elamin
Published: May 2024

Introduction Obesity is increasing worldwide, and bariatric surgery (BS) is increasingly employed for weight management in women of reproductive age. An interplay between pregnancy and BS is very likely. A review of the challenges faced and solutions needed is warranted.

Materials and Methods A narrative, nonsystematic review of the international literature from a single online database (PubMed) was performed on July 23, 2023. All articles were included. The retrieved relevant literature is narrated in a concise thematic account.

Results BS carries major metabolic, mechanical, and vascular benefits, possibly accompanied by nutritional, vitamins, minerals, and micronutrient deficiencies, which might be clinical or subclinical. A few of the frequently reported postbariatric nutritional jeopardies could be augmented by the physiological changes of pregnancy, which need a different approach to management. Nutritional deficiencies during pregnancy could carry both maternal and fetal short- and long-term risks. Fetal risks may range from miscarriage to low birth weight, neural tube defects, congenital anomalies, cognitive impairment, and internal organ dysplasia. Postbariatric status is, by default, a high-risk pregnancy category, given the altered biochemical, vasomotor, and mechanical indices of any lady treated with BS. Postgastric bypass hypoglycemia (PGBH) is a relatively common phenomenon during pregnancy, and it usually calls for multidisciplinary action to control. A dedicated monitoring protocol before, during, and after pregnancy has been suggested in several guidelines to guard against the potentially devastating consequences to both mother and fetus.

Conclusions Weight reduction after BS enhances fertility. The optimum timing for ladies treated with BS to get pregnant is not very well established yet. However, various societies have provided multidisciplinary management guidance of management prior to and during pregnancy. Many nutritional supplements that are not routinely prescribed during pregnancy will be essential for those treated with BS. Further studies are still warranted to ensure the safe interim between BS and conception as well as the safety of various doses of medications used for postbariatric individuals, for instance, medications used for PGBH.
Nexus between boardroom independence and firm financial performance: evidence from South Asian emerging market
Authors: Khan Majid Jamal , Saleem Faiza , Ud Din Shahab , Yar Khan Muhammad
Published: May 2024

This study empirically investigates the linkage between boardroom independence and the financial performance of non-financial firms in an emerging market featured by family-controlled businesses and concentrated ownership. The relationship is tested in a sample of 152 non-financial firms listed on the Pakistan Stock Exchange over a period from 2003 to 2018. Firms’ financial performance is measured through return on assets (ROA), return on equity (ROE), market-to-book ratio (MBR), and Tobin’sQ(TQ), while boardroom independence is measured through the proportion of non-executive directors on the corporate board. Using the dynamic GMM approach to address the possibility of endogeneity, it was found that boardroom independence is significantly negatively related to the financial performance of the sample firms. This negative impact is due to the reason of close ties of outside independent directors (non-executive directors) with dominant shareholders and management in personal, financial, and social terms. A significant negative influence of the board size and CEO duality on firms’ financial performance was also observed. The present study will add to the existing literature on corporate governance and firm financial performance using firm-level manually collected data. Further, our findings will also help the policymakers by providing empirical insights for strengthening corporate governance mechanisms in emerging market economies, specifically in the context of Pakistan.
Visual propaganda in chinese central and local news agencies: a douyin case study
Authors: Zhao Jiaye , Zhang Dechun
Published: May 2024

This study examines short videos sourced from the Douyin accounts of Chinese central and local news agencies spanning the period from 2018 to 2023, aiming to shed light on the dynamics of visual propaganda within social media and short-form video content. A comprehensive analysis of 2852 short videos was undertaken, focusing on prevalent themes, visual motifs, and emotional persuasion techniques. The results delineate a divergence in focus between central and local news agencies: while the former prioritizes content related to the military, police, and firefighting, the latter emphasizes “livelihood warmth” topics. Central agencies predominantly feature soldiers, police officers, and firefighters, whereas local agencies portray individuals devoid of explicit political affiliations alongside other influencers. Emotional scrutiny unveils a contrast in strategies, with central agencies predominantly evoking emotions such as anger, disgust, fear, and intolerance, while local agencies employ anticipation, acceptance, and respect. This investigation underscores the profound influence of political authority within China’s propaganda framework, shaping both the substance and emotional resonance of political short videos within a hierarchical paradigm.
Exploring the dynamics of consumer engagement in social media influencer marketing: from the self-determination theory perspective
Authors: Gu Chenyu , Duan Qiuting
Published: May 2024

Influencer advertising has emerged as an integral part of social media marketing. Within this realm, consumer engagement is a critical indicator for gauging the impact of influencer advertisements, as it encompasses the proactive involvement of consumers in spreading advertisements and creating value. Therefore, investigating the mechanisms behind consumer engagement holds significant relevance for formulating effective influencer advertising strategies. The current study, grounded in self-determination theory and employing a stimulus-organism-response framework, constructs a general model to assess the impact of influencer factors, advertisement information, and social factors on consumer engagement. Analyzing data from 522 samples using structural equation modeling, the findings reveal: (1) Social media influencers are effective at generating initial online traffic but have limited influence on deeper levels of consumer engagement, cautioning advertisers against overestimating their impact; (2) The essence of higher-level engagement lies in the ad information factor, affirming that in the new media era, content remains ‘king’; (3) Interpersonal factors should also be given importance, as influencing the surrounding social groups of consumers is one of the effective ways to enhance the impact of advertising. Theoretically, current research broadens the scope of both social media and advertising effectiveness studies, forming a bridge between influencer marketing and consumer engagement. Practically, the findings offer macro-level strategic insights for influencer marketing.
State-of-health estimation for lithium-ion batteries based on GWO–VMD-transformer neural network
Authors: Wang Haofan , Sun Jing , Zhai Qianchun
Published: May 2024

State-of-health (SOH) estimation of lithium-ion batteries stands as a fundamental metric within the battery management system. It reflects the current level of battery aging and is important for early warning of battery failure to avoid unsafe battery behavior. Therefore, accurate SOH estimation can ensure safe and reliable battery operation. In this paper, the capacity data of the discharge phase are used as the input of the SOH estimation model, and a gray wolf optimization (GWO)–variable mode decomposition (VMD)-transformer-based SOH estimation method for lithium-ion batteries is proposed in a data-driven framework. First, the GWO algorithm is adopted to optimize VMD to decompose the original battery capacity degradation sequence into a series of intrinsic mode functions (IMFs). Then, the transformer is used to separately predict each of these IMFs. Finally, the predicted values of each IMF are integrated to obtain the final prediction of the battery capacity degradation sequence. The model undergoes testing across various datasets, and comparative evaluations are conducted against other data-driven prediction models. The experimental findings underscore the superior SOH estimation performance of the proposed method, along with its robustness when confronted with diverse types of lithium-ion batteries, spanning distinct operational conditions and different aging degrees.
Characteristics of very-large-scale motions in natural rivers based on large eddy simulation
Authors: Wang Zhili , Liu Shangwu , Lu Shengjie , Xian Ruisi , Li Danxun
Published: May 2024

Exploring very-large-scale motions (VLSMs) in open channel flows (OCFs) is crucial for comprehensively understanding material transport and energy exchange. While previous studies focused on OCFs in ideal flumes with simple boundaries, this paper presents large eddy simulation (LES) results on the existence and scale characteristics of VLSMs in complex river morphologies with the Minjiang River in southwestern China as a case study. This research demonstrates that the OpenFOAM-based LES model is capable of accurately reconstructing the time-averaged flow field and providing instantaneous velocity data that capture VLSMs with sufficient resolution. Spectrum analysis of the streamwise fluctuating velocity shows that VLSMs are present in the straight segment of the river, with streamwise wavelengths approximately (16–22) times the water depth but are absent in the bend and confluence segments due to the suppression by secondary currents. This article validates the effectiveness of LES in examining the characteristics of VLSMs in natural rivers, thereby laying a good foundation for further studies on the impacts of such structures on sediment transport and pollutant dispersion.
Repeatability and reproducibility of physically consistent single sheet testing with H-coil
Authors: Shilyashki Georgi , Pfützner Helmut
Published: May 2024

Measurements of magnetic losses of electric steel are usually performed by International Electrotechnical Commission standardized Epstein testers or Single Sheet Testers (SSTs). According to round robin tests, the corresponding levels of repeatability are of the order of 0.1%, and those of reproducibility are of the order of 1%. However, orders of absolute accuracy are unknown due to the applied “current method.” Here, we report corresponding tests for the so-called “physically consistent SST.” Consistency is achieved by a “giant” tangential field coil on a 50 cm long and 17 cm wide soft magnetic sample, using a thin amorphous yoke for magnetization. Tests were made in two labs with very different working conditions (sea levels of 200 and 1100 m, respectively), with very similarly built-up testers. Measurements were made for peak inductions between 1 and 1.9 T. For two distributed samples, the repeatability errors were lower than 0.3%, and the reproducibility errors were lower than 1%. This indicates that SSTs with an H-coil are not less reliable than current based ones. However, the absolute accuracy can be estimated to be much better, being close to 2%.
From Topological Nodal-Line Semimetals to Quantum Spin Hall Insulators in Tetragonal SnX Monolayers (X=F, Cl, Br, I)
Authors: Zhu 朱 Ye 晔 , Zhao 赵 Bao 宝 , Xue 薛 Yang 阳 , Xu 徐 Wei 玮 , Xu 徐 Wenting 文婷 , Yang 杨 Zhongqin 中芹
Published: May 2024

Two-dimensional (2D) topological materials have recently garnered significant interest due to their profound physical properties and promising applications for future quantum nanoelectronics. Achieving various topological states within one type of materials is, however, seldom reported. Based on first-principles calculations and tight-binding models, we investigate topological electronic states in a novel family of 2D halogenated tetragonal stanene (T-SnX, X = F, Cl, Br, I). All the four monolayers are found to be unusual topological nodal-line semimetals (NLSs), protected by a glide mirror symmetry. When spin-orbit coupling (SOC) is turned on, T-SnF and T-SnCl are still ascertained as topological NLSs due to the remaining band inversion, primarily composed of Sn pxy
orbitals, while T-SnBr and T-SnI become quantum spin Hall insulators. The phase transition is ascribed to moving up in energy of Sn s orbitals and increasing of SOC strengths. The topology origin in the materials is uniformly rationalized through elementary band representations. The robust and diverse topological states found in the 2D T-SnX monolayers position them as an excellent material platform for development of innovative topological electronics.
One consistency relation for all single-field inflationary models
Authors: Namjoo Mohammad Hossein
Published: May 2024

In this paper, we present a non-Gaussianity consistency relation that enables the calculation of the squeezed limit bispectrum of the curvature perturbation in single-field inflationary models by carefully inspecting the background evolution and the linear perturbation theory. The consistency relation is more general than others in the literature since it does not require any specific symmetry, conservation of the curvature perturbation at large scales, attractor background evolution or canonical kinetic energy of the inflaton field. We demonstrate that all known examples of the squeezed limit bispectrum in single-field models of inflation can be reproduced within this framework.
Toward a Direct Measurement of the Cosmic Acceleration: The Pilot Observation of HI 21 cm Absorption Line at FAST
Authors: Kang Jiangang , Lu Chang-Zhi , Zhang Tong-Jie , Zhu Ming
Published: May 2024

This study presents results on detecting neutral atomic hydrogen (H i) 21 cm absorption in the spectrum of PKS PKS1413+13 at redshift z = 0.24670041. The observation was conducted by FAST, with a spectral resolution of 10 Hz, using 10 minutes of observing time. The global spectral profile is examined by modeling the absorption line using a single Gaussian function with a resolution of 10 kHz within a 2 MHz bandwidth. The goal is to determine the rate of the latest cosmic acceleration by directly measuring the redshift evolution of the H i 21 cm absorption line with Hubble flow toward a common background quasar over a decade or longer time span. This will serve as a detectable signal generated by the accelerated expansion of the Universe at redshift z < 1, referred to as redshift drift

z

̇

or the SL effect. The measured H i gas column density in this DLA system is approximately equivalent to the initial observation value, considering uncertainties of the spin temperature of a spiral host galaxy. The high signal-to-noise ratio of 57, obtained at a 10 kHz resolution, strongly supports the feasibility of using the H i 21 cm absorption line in DLA systems to accurately measure the redshift drift rate at a precision level of around 10−10 per decade.
EEG motor imagery decoding: a framework for comparative analysis with channel attention mechanisms
Authors: Wimpff Martin , Gizzi Leonardo , Zerfowski Jan , Yang Bin
Published: May 2024

Objective. The objective of this study is to investigate the application of various channel attention mechanisms within the domain of brain-computer interface (BCI) for motor imagery decoding. Channel attention mechanisms can be seen as a powerful evolution of spatial filters traditionally used for motor imagery decoding. This study systematically compares such mechanisms by integrating them into a lightweight architecture framework to evaluate their impact. Approach. We carefully construct a straightforward and lightweight baseline architecture designed to seamlessly integrate different channel attention mechanisms. This approach is contrary to previous works which only investigate one attention mechanism and usually build a very complex, sometimes nested architecture. Our framework allows us to evaluate and compare the impact of different attention mechanisms under the same circumstances. The easy integration of different channel attention mechanisms as well as the low computational complexity enables us to conduct a wide range of experiments on four datasets to thoroughly assess the effectiveness of the baseline model and the attention mechanisms. Results. Our experiments demonstrate the strength and generalizability of our architecture framework as well as how channel attention mechanisms can improve the performance while maintaining the small memory footprint and low computational complexity of our baseline architecture. Significance. Our architecture emphasizes simplicity, offering easy integration of channel attention mechanisms, while maintaining a high degree of generalizability across datasets, making it a versatile and efficient solution for electroencephalogram motor imagery decoding within BCIs.
Design of Pseudorandom Signal Generator Based on a Dual Memristor Chaotic System
Authors: Fang Na , Wang Jiabin , Jiang Yong , Liang Wanyong
Published: May 2024

This paper constructs a pseudo-random signal generator based on a dual memristor chaotic system. Firstly, the chaotic characteristics of the dual memristor chaotic system were explored through theoretical analysis and MATLAB numerical simulation, and a MULTISIM simulation circuit for the dual memristor chaotic system was constructed. Then, based on the threshold decision quantization method, a pseudorandom signal generator quantization circuit is formed by connecting an inverter amplifier and a hysteresis comparator on the output side of the analog circuit. Finally, the randomness of the pseudorandom sequence is discussed by NIST test and correlation analysis. The analysis results show that the pseudorandom sequence generated by the pseudo-random signal generator based on the dual memristor chaotic system exhibits good randomness.
Resonance Detection Method of AC-DC Hybrid Micro-grid Based on Wavelet Transform and Fast Fourier Transform
Authors: Gao Jing , Zhao Yuan , Lu Yi , Xu Guangda
Published: May 2024

The grid connection of a mass of distributed power sources in the AC/DC hybrid micro-grid will cause harmonics, voltage sags, voltage fluctuations, and flicker in the grid, which seriously affects the power quality of the grid. Therefore, the power quality problems such as the resonance generated by the AC/DC hybrid micro-grid need to be studied urgently. In this paper, a resonance detection technology based on the combination of wavelet transform (WT) and fast Fourier transform (FFT) is proposed. This method uses wavelet transform to process the high-frequency and low-frequency parts of the signal separately, and eliminates part of the interference signal. The method then uses the FFT to obtain the resonance content. The AC/DC hybrid micro-grid resonance detection method based on WT and FFT can not only determine the time and amplitude of the resonance signal, but also filter the interference signal and improve the accuracy of frequency domain analysis. It is verified by simulation that the algorithm can detect the resonance of the AC/DC hybrid micro-grid.
An Accurate Modeling Method of Body-thread of Penetration Fuze in FEM
Authors: Ma Mengxin , Yang Dong , Xu Tengfei
Published: May 2024

To address the issue that the influence of body-thread on the acceleration signal characteristics in penetration fuze is ambiguous, an accurate modeling method of body-thread is proposed in the finite element method (FEM). The body-thread element segments are obtained by the three-dimensional entity thread model, the initial layer nodes set and elements on the outer surface of the thread are established, and the initial layer elements are copied, rotated, and translated. Repeat this transformation, and get a complete thread model. This method is applied to simulation analysis of a warhead penetrating 4-layer concrete plates, and the influence of thread connection on acceleration signal characteristics in penetration fuze is studied. By comparing the acceleration signal and frequency spectrum of the proposed thread model with that of the simplified thread model, the amplitude of the acceleration signal of the proposed one is smaller than that of the simplified one in some certain frequency spectrum. It shows that the thread connection structure has with damping effect and effectively reduces the high-frequency interference of acceleration signal in penetration fuze.
P-index: A Generalized Statistical Aggregation Metric
Authors: Jing Yunpeng
Published: May 2024

Data aggregation serves as a crucial technique in data analysis, particularly in the context of data dimensionality reduction. The most common approach involves employing statistical aggregation metrics such as mean, median, and others to characterize a dataset. However, different statistical aggregation metrics may yield disparate results, making the discrimination and selection of suitable metrics for describing data a research topic. Addressing this, the paper proposes a generalized statistical aggregation metric, categorizing several commonly used metrics under specific scenarios. This model offers a novel perspective for choosing among different statistical aggregation metrics and assists researchers in developing a deeper understanding of common statistical aggregation metrics. The introduction of this generalized metric provides a flexible and comprehensive method for considering multiple statistical measures simultaneously, enabling a more accurate grasp of the dataset’s essence and offering reliable insights for decision-making. The study contributes a new viewpoint to the selection and application of statistical aggregation metrics, advancing discussions in multi-objective optimization and data interpretability.
Minimum Volume Constraint with Perturbation for Non-negative Matrix Factorization
Authors: Sun Li , Yang Song , Yu Ruilin , Zhang Xinyuan
Published: May 2024

Nonnegative matrix factorization (NMF) has been applied in hyperspectral unmixing. The nonconvexity of the NMF’s cost function leads to solutions that are only locally optimal. Adding regularized terms to the NMF helps improve the solutions. In this study, we proposed a regularized NMF model, the regularized tern is the minimum volume constraint with perturbation. The NMF model is solved with multiplicative updated rules. Numerical results verified that adding a disturbance term to the minimum volume constraint effectively improves the spectral curve’s local accuracy while maintaining the original model’s advantages.
The Signed Total Mixed Roman Domination Numbers of Graphs
Authors: Hong Xia , Zhang Li , Guo Xiaobing
Published: May 2024

The problem of signed domination of graphs is a typical optimization problem. It requires that each vertex and edge be assigned a feasible label so that the sum of assigned labels is minimized. First, we propose the concept of a signed total mixed Roman domination number and introduce the related research progress. Finally, we determine several lower bounds of the signed total mixed Roman domination numbers which depend on the parameters of vertex number and edge number, degree and leaf number.
Research on Multi-target Tracking Algorithm Based on Track Segment Association
Authors: Yin Song , Liang Qing
Published: May 2024

In the process of multi-target tracking, the complex underwater acoustic channel, target model mismatch, target strong maneuvering and other factors are easy to cause track interruption and rerun, which have a bad influence on the situation assessment and tactical decision of the Unmanned sonar system. Aiming at the problem of track interruption, this paper integrates the track adhesion algorithm into the active multi-target tracking algorithm. Simulation results show that the track adhesion algorithm can effectively improve the correct track association rate and track lifetime. By comparing the effect of the new and old methods with the sea test data, the track adhesion can effectively solve the problem of track interruption in the case of target track maneuvering and improve the track life.
Modelling and Impact Analysis of Combined Dam Failure of Small Tandem Reservoir Groups in Hilly Areas
Authors: Liu Hu , Sang Guoqing , Jiang Daijing
Published: May 2024

Numerous small reservoirs in hilly areas play a significant role in flood control and profit-making in the basin, but there is also a risk of dam failure when encountering special circumstances such as excessive flooding, which may cause large losses downstream. In this paper, we take the small reservoirs in Shandong Province as the research object, analyze the hydraulic topology of three types of tandem reservoirs, generalize the shape of the breach by using the transient lateral local one-break to the end, calculate the dam-break flooding process by using the quadratic parabolic method, and simulate the dam-break by using the MIKE21 model based on the principle of the two-dimensional incompressible Reynolds mean stress equation for the incompressible fluid, and analyze the peak flow under various combinations of dam-break flow by setting various combinations of the number of dam-breaks and the timing of dam-break simulation. By setting various combinations of dam failure numbers and timing, we analyzed the changing rules of peak dam failure flow, inundation area and other elements under various combinations, and sought the most unfavorable combinations and parameters such as the timing of dam failure, and the results of the analyses can provide technical support for the assessment of the risk of dam failure in the tandem reservoirs in the hilly area and the risk correspondence.
An Improved Sobol Sensitivity Analysis Method
Authors: Chen Lixin , Xu Zhongxiang , Huang Desuo , Chen Zhining
Published: May 2024

The Sobol method is a variance-based global sensitivity analysis method that evaluates single-input and multiple-input interaction effects by calculating the contribution of a single input to the output variance and the contribution of multiple inputs to the output variance. The Sobol method requires each input to obey a uniform distribution of U [0,1], but it is difficult to meet the requirements in practice. Taking the sum function as an example, this paper analyzes the inapplicability of the existing Sobol method when the input does not obey the uniform distribution U [0,1]. To solve the inapplicability of the Sobol method and broaden the application scope, an improved Sobol sensitivity analysis method is proposed. First, the effect of the joint probability density function not 1 on sensitivity calculation is studied; second, the input parameters are changed to uniform distribution U [0,1] through variable substitution; finally, a complete algorithm model is presented and logical sensitivity analysis results are obtained. Application verification shows that the improved Sobol method is more scientific, applicable and practical.
Analysis of Vibration Characteristics of Horizontal Axis Wind Turbine Tower under Random Wind Action
Authors: Yang Hexu , Li Xiaopeng , Liu Wenwen , Yang Zemin
Published: May 2024

As the main supporting structure of wind turbines, the service quality of towers directly affects the operational safety of wind turbines. Researching tower vibration characteristics, evaluating its service quality and early warning of damage is an important means to improve the operational safety of wind turbines. Firstly, the external load conditions of the wind turbine tower were determined through wind load calculation, and the load and dynamic theory of the variable pitch torque wind turbine tower were summarized. Secondly, based on the Euler-Lagrange energy equation, the Lagrange equation of the simplified dynamic model of the wind turbine tower is established, and the vibration characteristics of the tower under different wind speeds are analyzed. The research results can provide a theoretical basis for the research on the characteristics of the wind turbine tower.
Inference of Dynamic Spatial Panel Data Model and Its Application in Carbon Emission Analysis
Authors: Gu Wenbo , Kang Fangyuan
Published: May 2024

The Spatial Dynamic Panel Data (SDPD) model is a widely used statistical model in the fields of economics and social sciences and has been the subject of extensive research by many scholars in recent years. Existing methods for parameter estimation primarily focus on improvements to the Generalized Method of Moments (GMM) and Quasi-Maximum Likelihood (QML). In this paper, we employ the method of Empirical Likelihood (EL) for statistical inference of the dynamic spatial panel data model and obtain confidence regions for the parameters. Through numerical simulations, we present the performance of the confidence regions obtained using the Empirical Likelihood (EL) and the Asymptotically Normal (NA) methods under finite samples and compare the two approaches. Finally, we analyze carbon using the suggested model and techniques.
Integrated Simulation Research of Multi-natural Energy-driven Unmanned Surface Vehicle
Authors: Chen Ao , Chen Tianding , He Hong , Wang Hui , Fan Yimei , Yu Xin
Published: May 2024

In response to the limitations of existing unmanned surface vehicles in complex marine environments, where they often fail to meet the requirements for extended endurance, broad operational range, offshore missions, and prolonged operational durations, an autonomous Unmanned Surface Vehicle (NUSV) has been designed and developed. The NUSV is propelled by wind, solar, and wave energy sources. Concerning wind energy, a micro wind energy storage mechanism based on a spiral spring has been designed to enable power generation in low-wind conditions. A wave energy transmission device, complete with a dynamic model, has been devised for wave energy. This device converts torque generated from wave action in different directions into a unified torque, providing continuous power to drive the generator. Solar energy is harnessed using Maximum Power Point Tracking (MPPT) algorithms to ensure optimal operation of the solar panels. The electrical energy generated from these three natural sources is stored using Pulse Width Modulation (PWM) and DC-DC Boost converters. A programmable logic controller manages and allocates this stored electrical energy for the NUSV’s equipment, including underwater propulsion systems, surface cameras, laser radar, GPS, and other electronic devices. This integration of wind, solar, and wave energy sources enables the NUSV to meet power demands, allowing for long-duration operations at sea, extended offshore missions, wide operational ranges, and prolonged mission durations.
Improved GMMKNN Hybrid Recommendation Algorithm
Authors: Hao Yaxian , Feng Lijiao
Published: May 2024

This paper proposes a hybrid recommendation algorithm that combines the advantages of Gaussian Mixture Model (GMM) and K-Nearest Neighbors (KNN) algorithms. The algorithm first applies GMM to cluster the training data, grouping users with similar interests using clustering techniques. It then utilizes the KNN algorithm for prediction. During the KNN recommendation process for a target user, the algorithm searches for neighboring users with similar interests and features within the same cluster. This significantly reduces the search scope of the nearest neighbors, thanks to the assistance of the GMM algorithm. The algorithm then selects the K most similar neighbors from the target user’s cluster as the candidate pool for personalized recommendations. Additionally, the algorithm improves the weight calculation method by incorporating a Gaussian kernel function for weight estimation. Experimental results on the dataset demonstrate that the proposed improved algorithm effectively enhances the accuracy of prediction results.