bluuebunny/crossref_metadata_2025 huggingface dataset:
Pulsed Production of Antihydrogen in AEgIS
Authors: Zurlo N. , Auzins M. , Bergmann B. , Bonomi G. , Brusa R.S. , Burian P. , Camper A. , Castelli F. , Ciury R. , Consolati G. , Doser M. , Farricker A. , Glöggler L. , Graczykowski Ł. , Grosbart M. , Guatieri F. , Gusakova N. , Haider S. , Huck S. , Janik M. , Kasprowicz G. , Khatri G. , Kłosowski Ł. , Kornakov G. , Krumins V. , Lappo L. , Linek A. , Malamant J. , Malbrunot C. , Mariazzi S. , Nowak L. , Nowicka D. , Oswald E. , Pagano D. , Penasa L. , Piwiński M. , Pospisil S. , Povolo L. , Prelz F. , Rangwala S. , Rienäcker B. , Røhne O.M. , Rotondi A. , Sandaker H. , Smolyanskiy P. , Sowiński T. , Tefelski D. , Testera G. , Volponi M. , Welsch C.P. , Wolz T. , Zawada M. , Zielinski J. ,   (AEgIS collaboration)
Published: December 2023

Low-temperature antihydrogen atoms are an effective tool to probe the validity of the fundamental laws of Physics, for example the Weak Equivalence Principle (WEP) for antimatter, and -generally speaking- it is obvious that colder atoms will increase the level of precision.

After the first production of cold antihydrogen in 2002 [1], experimental efforts have substantially progressed, with really competitive results already reached by adapting to cold antiatoms some well-known techniques pre- viously developed for ordinary atoms. Unfortunately, the number of antihydrogen atoms that can be produced in dedicated experiments is many orders of magnitude smaller than of hydrogen atoms, so the development of novel techniques to enhance the production of antihydrogen with well defined (and possibly controlled) conditions is essential to improve the sensitivity.

We present here some experimental results achieved by the AEgIS Collaboration, based at the CERN AD (Antiproton Decelerator) on the production of antihydrogen in a pulsed mode where the production time of 90% of atoms is known with an uncertainty of ~ 250 ns [2]. The pulsed antihydrogen source is generated by the charge-exchange reaction between Rydberg positronium (Ps*) and an antiproton (p¯): p¯ + Ps* → H¯* + e−, where Ps* is produced via the implantation of a pulsed positron beam into a mesoporous silica target, and excited by two consecutive laser pulses, and antiprotons are trapped, cooled and manipulated in Penning-Malmberg traps. The pulsed production (which is a major milestone for AEgIS) makes it possible to select the antihydrogen axial temperature and opens the door for the tuning of the antihydrogen Rydberg states, their de-excitation by pulsed lasers and the manipulation through electric field gradients.

In this paper, we present the results achieved by AEgIS in 2018, just before the Long Shutdown 2 (LS2), as well as some of the ongoing improvements to the system, aimed at exploiting the lower energy antiproton beam from ELENA [3].
Evaluation of water equivalent thicknesses using the IEM-CSIC scanner prototype
Authors: Nerio Amanda Nathali , Briz José Antonio , García Borge María José , Nácher Enrique , Tengblad Olof , Perea Ángel , García Távora Vicente
Published: December 2023

Proton imaging has been proposed as an alternative low-dose imaging technique for acquiring relative stopping power (RSP) maps and for patient positioning. In proton therapy and hadrontherapy, the water equivalent thickness (WET) of a material represents its radiological thickness, however, its calculation requires computationally intensive methods or approximate solutions. At IEM-CSIC, we have developed a scanner prototype for imaging with protons composed of two double-sided silicon strip detectors (DSSSD) and fast scintillators with high energy resolution, detectors that are commonly used in Experimental Nuclear Physics. Two custom-made samples of aluminum, air, and polymethyl methacrylate (PMMA) were imaged and their proton radiography images (pRads) are presented in terms of WET. Pattern reproduction, spatial resolution, and sensitivity to di↵erent materials were studied. We present pRads of our samples obtained using a rather traditional approach to compute WET values. All three materials of the studied samples, aluminum, PMMA, and air, were well distinguished; the resulting WET values were in good agreement between samples.
Long range plans to study the nuclear equation-of-state from sub- to supra-saturation densities with heavy-ion collisions
Authors: Le Fèvre A. , Colonna M. , Verde G. , Agarwal K. , Aichelin J. , Aumann T. , Chbihi A. , Cozma M.D. , De Filippo E. , Elfner Hannah , Galatyuk T. , Hartnack Ch. , Leifels Y. , Pirrone S. , Senger P. , Stroth J. , Russotto P. , Schmidt H.R. , Schwenk A. , Wolter H.
Published: December 2023

We cover here the present state-of-the-art in constraining the nuclear equation-of-state (EoS) and the symmetry energy using heavy-ion collisions (HIC), from sub- to supra-saturation densities, from Fermi to (ultra-) relativistic beam energies. We also discuss how HIC constraints on the EoS contribute to the knowledge of thermodynamical properties of neutron star matter. Necessary improvements and challenges are outlined, in particular in the perspective, for HICs, of staying competitive with future astrophysical multimessenger observations.
Upgrade to the focal-plane detector system of the S800 spectrograph at FRIB
Authors: Cortesi Marco , Pereira Jorge , Dziubinski Sean , Lidia Steven , Zegers Remco , Bazin Daniel , Cerizza Giordano , Asciutto Joseph , Gade Alexandra
Published: December 2023

The present work describes the ongoing upgrade of the focal-plane detector system and the associated data acquisition system of the large-acceptance S800 magnetic spectrograph. It includes the development of an innovative micro-pattern gaseous detector readout for the tracking system, a novel energy-loss detector concept for Z-identification, and a high resolution optical readout for the timing scintillator detector. The upgraded focal-plane detector system will allow for improved particle identification for heavy-ion beams above Z=100, at higher rate capability (> 25 kHz).
Study on position tracking algorithm of large-inertia artillery with terminal sliding mode control
Authors: HAO Kunpeng , YANG Guolai
Published: December 2023

The large-inertia artillery has complex structure and high coupling between components. Due to the processing technology, the error between motor shaft position and the actual load position is inevitable and hardly to be compensated. The situation get worse when the system running in high speed, where the error changes more violently and so-called "vibration" phenomenon shows up. The study establishes a detailed mode of servo system including double-motor control, position-loop control, moment model of gears, and feedback of position sensors. Then a position tracking algorithm with terminal sliding mode control is proposed and verified in artillery system. The experiment shows that this algorithm effectively eliminates the "vibration" phenomenon, enables the servo computer to directly use the load position of the artillery as the control variable, and improves the position tracking accuracy and operational stability of artillery system.
Optimization method of high parameter spiral groove mechanical seal based on axiomatic design theory
Authors: LI Jianke , LIU Chenyang , LEI Longsheng , WANG Jianlei , JIA Qian
Published: December 2023

At present, in order to improve the performance of spiral groove mechanical seals, the structural parameters of seals are mostly adjusted based on the experience of designers. The integration degree of existing mechanical seal performance research examples is low, and the whole performance optimization process lacks of scientific theoretical framework to guide. In order to solve this problem, combining the axiomatic design theory with the existing mechanical seal performance research, a structural optimization method of spiral groove mechanical seal based on axiomatic design theory was put forward. This method defines the mapping relationship between the three-level functional requirement domain and the design parameter domain of the spiral groove mechanical seal, and thus develops 14×14 diagonal optimization matrix. The research results show that the introduction of axiomatic design provides a basic theoretical framework for the performance optimization of spiral groove mechanical seals and decomposes the optimization process into several design modules, which improves the efficiency and accuracy of the optimization design of spiral groove mechanical seals and has good application value.
Correlation analysis of lift fan lip feature geometry and aerodynamic performance
Authors: WANG Siwei , WANG Yangang , LIU Hanru , CHEN Yanjun , LIU Shuli
Published: December 2023

In hover, the lip of a lift fan plays a crucial role, contributing to nearly half of the lift for the VTOL aircraft power plant. Thus, investigating the geometric parameters that influence lip performance is of significant importance. In this study, four types of lift fan lips were designed, tailored to meet specific application requirements. Numerical analysis, validated through experimental data, was employed to examine the flow field and the geometric factors that lead to variations in lip performance. Based on the findings, the relationship between lip geometric parameters and aerodynamic performance was thoroughly investigated and confirmed. The results demonstrate that, at a rotational speed of 10 000 r/min, the non-dimensional lift and non-dimensional mass flow of the lemniscate lip exhibit improvements of 33% and 9.5%, respectively, compared to lips designed based on NACA65. Among the various lip configurations, it is found that the performance parameters of the lip are optimal when the slope of the inner surface equaled twice the slope of the lemniscate. On the other hand, when the slope deviated from this optimal value, whether greater or lesser, a reduction in lip performance was observed. Specifically, at a rotational speed of 10 000 r/min, the lip designed based on a lemniscate slope could increase the total lift of the lift fan by 5.6% when compared to the lemniscate lip.
Image emotion analysis based on semantic concepts
Authors: YANG Hansen , FAN Yangyu , LYU Guoyun , LIU Shiya , GUO Zhe
Published: December 2023

With the increasing number of users express their emotions via images on social media, image emotion analysis attracts much attention of researchers. For the ambiguity and subjectivity of emotion, image emotion analysis is more challenging than other computer vision tasks. Previous methods merely learn a direct mapping between image feature and emotion. However, in emotion perception theory of psychology, it is demonstrated that human beings perceive emotion in a stepwise way. Therefore, we propose a novel image emotion analysis framework that makes use of emotional concepts as middle-level feature to bridge image and emotion. Firstly, the relationship between the concept and the emotion is organized in the form of knowledge graph. The relation between the image and the emotion in the semantic embedding space is explored where the knowledge is encoded into. On the other hand, a multi-level deep metric learning method to optimize the model from both label level and instance level is proposed. Extensive experimental results on two image emotion datasets, demonstrate that the present approach performs favorably against the state-of-the-art methods on both affective image retrieval and classification tasks.
Dynamic modeling and performance analysis of metal hydride hydrogen storage system
Authors: ZHU Dan , WANG Han , WU Shengquan , FENG Zhi , ZHAO Xuan
Published: December 2023

Metal hydride hydrogen storage has the advantages of high hydrogen storage volume density, high safety, and high hydrogen purity, which can meet the hydrogen storage and supply needs of fuel cells in both mobile and fixed scenarios. It has become one of the most promising hydrogen storage methods. This work studies the dynamic performance of metal hydride hydrogen storage systems under absorption and desorption process by establishing dynamic models and heat exchange models. The dynamic properties of metal hydride hydrogen storage system are analyzed in different reaction process with the experimental test. Results show that when the ambient temperature is within a certain range, low temperatures are conducive to hydrogen absorption, while high temperatures can improve hydrogen release dynamics. Besides, raising the flow rate of hydrogen and reducing the volume fraction of hydrogen storage materials can help to improve the efficiency of hydrogen absorption and desorption reaction.
Remote sensing target detection algorithm based on perceptual extension and anchor frame best-fit matching
Authors: HONG Wei , ZHAO Xiangmo , WANG Peng , LI Xiaoyan , DI Ruohai , LYU Zhigang , WANG Chu
Published: December 2023

Aiming at the small imaging, complex background and crowded distribution of remote sensing image targets, a remote sensing image target detection algorithm (HQ-S2ANet) based on perceptual extension and anchor frame optimal matching is proposed by using the rotating target detection method S2ANet as a baseline network. Firstly, a cooperative attention(SEA) module is built to capture the relationship among the feature pixels when extending the model perception area to realize the relationship modeling between the target and the global. Secondly, the feature pyramid (FPN) feature fusion process is improved to form a perceptual extension feature pyramid module (HQFPN), which guarantees the low-level detail position information in the down sampling process when extending the perception area to enhance the model information capturing capability. Finally, a high-quality anchor frame is used to detect the target by using the high quality anchor frame as the baseline network. The high-quality anchor frame matching method (MaxIoUAssigner_HQ) is used to control the anchor frame truth value assignment by using a constant factor to ensure the recall rate while preventing the generation of low-quality anchor frame matching. The experimental results show that, under the DOTA dataset, the average accuracy(mAP) of HQ-S2ANet is improved by 3.1%, the parameters number increased by only 2.61M and the average recall(recall) is improved by 1.6% compared with the S2ANet algorithm, and the present algorithm effectively enhances the detection capability of the remote sensing image target.
Fratura atípica de tíbia tratada com osteossíntese associada a artroplastia total do joelho: Relato de caso
Authors: Lopes Márcio Bezerra Gadelha , Araújo Leonardo Heráclio do Carmo , Lustosa Leonardo Miranda , Alencar Neto Jonatas Brito de , Felipe Marcos Rainier de Brito
Published: December 2023

Bifosfonatos são amplamente usados no tratamento da osteoporose; porém, predispõem ao surgimento de fraturas atípicas. A região subtrocantérica femoral é usualmente acometida, mas outros ossos também são afetados. Fraturas atípicas da tíbia em pacientes portadores de gonartrose grave são um desafio terapêutico. O presente trabalho relata o caso de uma paciente idosa com gonartrose avançada que apresentou fratura atípica tibial. A paciente fazia uso prolongado de bifosfonatos para osteoporose, com quadro de dor e limitação funcional decorrentes da gonartrose, que progrediu para dor súbita na metáfise tibial à direita, impedindo a deambulação. Radiografias evidenciaram artrose grave bilateral; varismo acentuado; erosão medial tibial e femoral; e fratura no terço proximal da diáfise tibial direita. Trataram-se a fratura e a artrose à direita por osteossíntese com placa bloqueada e artroplastia total do joelho com estabilização posterior e base fixa. Após reabilitação física, relatou-se melhora significativa da dor e da função, readquiriu-se a marcha independente e alcançou-se arco de movimento de 0 a 100°. Após um ano, as radiografias mostraram consolidação da fratura e alinhamento satisfatório dos eixos dos membros inferiores. A coexistência de artrose grave e fratura atípica dificultou o tratamento. Contudo, o resultado foi satisfatório e a abordagem com osteossíntese e artroplastia simultâneas mostrou-se adequada.
Padronização do estudo radiográfico do pé pela caixa Niza
Authors: Fernandes João Vitor de Castro , Oliveira Lucas Pena de , Fernandes Pedro Agner Aguiar , Niza Altair Carlos , Cerqueira Ana Luiza de Souza Lima
Published: December 2023

Objetivo Este estudo propõe a utilização da Caixa Niza, dispositivo criado com a finalidade de diminuir os erros interpretativos entre profissionais e facilitar o correto posicionamento das estruturas radiografadas ao padronizar as incidências radiográficas ortopédicas do pé anteroposterior, perfil com carga e Saltzman.

Métodos Pesquisa descritiva, material coletado em Ambulatório de Ortopedia em serviço terciário de cidade brasileira de grande porte. Utilizado aparelho de radiografia marca Lotus X, modelo HF 500M, capacidade de 500 miliamperes e 125 quilovolts, distância foco-filme de 100cm, chassi radiográfico 24 × 30 cm e os comandos do aparelho ajustados para 100 mA, 5mA/seg e 60 quilovolts dependendo do tamanho variável dos pés. Exames realizados pela mesma equipe de técnicos em radiografia previamente treinados com supervisão dos autores. O chassi é posicionado em três espaços específicos da Caixa conforme a incidência proposta. Foram analisados dados de 50 imagens de pessoas entre 18 e 70 anos.

Resultados A avaliação das radiografias após utilização do dispositivo proposto ocorreu de modo geral com qualidade satisfatória, permitindo correta identificação dos elementos anatômicos do pé e tornozelo e reconstrução angular. Pequenas variações nas imagens devido ao tamanho dos pés são aceitáveis e esperadas, sendo possível perceber padronização das radiografias.

Conclusão A Caixa proposta se mostra um bom método de minimizar as interferências e evitar erros de interpretação radiográfica, proporcionando qualidade e agilidade ao exame, diminuindo custo e repetições desnecessárias. É inovador, um dispositivo de baixo custo, de material reciclável e biodegradável.
Acurácia dos marcadores sorológicos, do líquido sinovial, da cultura microbiológica e do exame histopatológico para o diagnóstico de infecção periprotética do joelho
Authors: Mozella Alan de Paula , Cobra Hugo Alexandre de Araújo Barros , Minamoto Sandra Tie Nishibe , Salim Rodrigo , Leal Ana Carolina
Published: December 2023

Objetivo avaliar a sensibilidade, especificidade, valor preditivo positivo, valor preditivo negativo e acurácia dos testes sorológicos, dos marcadores do líquido sinovial, da cultura microbiológica de tecidos e do exame histopatológico da membrana periprotética para o diagnóstico de infecção periprotética do joelho.

Métodos: estudo prospectivo, com pacientes submetidos à cirurgia de revisão de artroplastia total do joelho no período entre novembro de 2019 e dezembro de 2021. Foi realizado análise do marcadores sorológicos (VHS,PCR e D-dímero), do líquido sinovial (contagem de leucócitos e percentual de polimorfonucleares), cultura de tecidos periprotéticos e exame histopatológico da membrana periprotética de todos os pacientes.

Resultados 62 pacientes foram diagnosticados com infecção periprotética do joelho, pelos critérios do International Consensus Meeting 2018 (grupo infecção) e 22 pacientes integraram o grupo não infecção. A sensibilidade e especificidade da VHS foram de 83,6% e 45,4%, respectivamente. Os valores de sensibilidade e especificidade da PCR foram de 64,5% e 100% e as do D-dímero foram de 78,9%% e 25%, respectivamente. A sensibilidade e especificidade da contagem de leucócitos foi de 75,6% e 100%, e a do percentual de polimorfonucleares foi de 33% e 100%, respectivamente. A sensibilidade e especificidade das culturas de tecidos periprotéticos foi de, respectivamente, 77,4% e 100% A sensibilidade do exame histopatológico foi de 43,7% e a especificidade de 100%.

Conclusões A contagem total de leucócitos no líquido sinovial e as culturas microbiológicas dos tecidos periprotéticos foram os testes de maior acurácia para o diagnóstico de infecção periprotética em nossa série. O percentual de polimorfonucleares foi o teste de menor acurácia, em nosso estudo, para o diagnóstico de infecção periprotética.
Prevalência de dor neuropática em pacientes com osteoartrite
Authors: Zuluaga María Eugenia , Urbano Iveth , Tovar-Sanchez María Ana , Baena Catalina , Pacichana-Quinayaz Sara G. , Bonilla-Escobar Francisco J.
Published: December 2023

Objetivo O objetivo deste estudo foi determinar a prevalência de dor neuropática e caracterizar a qualidade de vida de pacientes com osteoartrite que consultaram um ambulatório de dor no sudoeste da Colômbia.

Métodos Este foi um estudo transversal realizado por meio de entrevista telefônica. Foram incluídos participantes ≥18 anos de idade com diagnóstico de osteoartrite. O questionário Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) foi utilizado para avaliação dos sintomas e sinais de dor neuropática e o Short Form-8 analisou a qualidade de vida.

Resultados A taxa de resposta foi de 54,1% (46/85). A razão homem:mulher foi de 5:1, com média de idade de 72 ± 10 anos. A maioria dos participantes (91,3%) apresentava dor intensa. A prevalência de dor neuropática foi de 28,3% (intervalo de confiança [IC] de 95% = 15,99-43,46) e a prevalência de dor neuropática entre mulheres foi de 84,6% (IC 95% = 54,55-98,01). Disestesias e dor paroxística foram relatadas por 92,3% dos indivíduos com dor neuropática. Em relação à qualidade de vida, as limitações na prática de atividade física foram as mais significativas e relatadas por 63% dos indivíduos.

Conclusão A dor neuropática foi prevalente e tinha impacto negativo na função física. Isso destaca a necessidade de estratégias terapêuticas direcionadas a vias específicas da dor neuropática em pacientes com osteoartrite.
Do cybercrime laws address emergent IoT security threats? The case of UAE federal cybercrime law regarding RFID technology
Authors: Miniaoui Sami , Muammar Sudad , Muhammad Nasiruddeen , Al Muraqab Nasser , Atalla Shadi
Published: December 2023

With the widespread use of radio-frequency identification (RFID) technology as a means for commerce and identification, new types of cybercrime have emerged. Accordingly, revisions to extant cybercrime law are required. This research attempts to determine the relevance of current UAE laws in addressing new cybercrimes on emergent technologies. We reviewed the literature to identify threats to RFID systems, classifying works into three categories: blocking, interception, and physical attacks. We mapped these categories to 50 articles of the UAE cybercrime law to assess their relevance. According to the distribution of law articles pertaining to RFID attacks, it was found that RFID communication interception attacks are not sufficiently addressed in the law and that further amendments are required in the UAE. Example of international statutes are highlighted as models.
What kind of discipline are we? A network analysis of British Politics
Authors: Byrne Christopher , Randall Nick
Published: December 2023

Research on British politics has traditionally been too reliant on a single model for understanding its field of inquiry—initially the Westminster model and then, since the 2000s, the governance-focused ‘differentiated polity model’. It has also been criticised for being preoccupied by the institutions that make up the Westminster system in terms of its substantive analytical focus, neglecting theory and international comparisons, failing to learn from other disciplines, and neglecting issues of age, gender, ethnicity and the environment (Marsh in Br Polit 7:43–54, 2012; Randall in Br Polit 7:17–29, 2012; BJPIR in Br J Polit Int Relat 24:3–10, 2022). This article aims to substantiate some of these claims using a network analysis of articles published in the journal British Politics to illuminate the who and the what of contemporary British politics research: Who authors it, which communities they form, what topics they focus on, and how they relate to the rest of the discipline. The evidence presented paints a picture of a valuable, but also still somewhat insular and fragmented discipline, and one that is itself inflected by structured inequalities.
Exploring the influence of teachers’ motivating styles on college students’ agentic engagement in online learning: The mediating and suppressing effects of self-regulated learning ability
Authors: Li Suqi , Xu Kexue , Huang Jun
Published: December 2023

Online learning has gradually become the new mainstream learning norm during the post-epidemic era. To ensure college students’ online learning effectiveness, they need to be proactively engaged in their online learning, which means that they need to maintain a high level of agentic engagement. However, it is not clear what factors influence college students’ agentic engagement in online learning environments. According to self-determination theory (SDT), the teacher, as an important external factor, can influence students’ learning engagement and learning effectiveness. Meanwhile, self-regulated learning (SRL) ability is important for college students in online learning. Based on existing theoretical foundations, therefore, the current study attempts to explore the following research questions: Are there relationships between teachers’ motivating styles (including autonomy-supportive style and controlling style), college students’ online SRL ability, and college students’ online learning agentic engagement? If yes, how does the former influence college students’ online learning agentic engagement? To respond to these research questions, random sampling was used to collect a total of 681 valid data from college students with experience in online learning. Then, a pilot test, exploratory factor analysis, and confirmatory factor analysis were first conducted to confirm the reliability and validity of the data. Correlational and mediating analyses were then conducted using SPSS 21.0. According to the results, firstly, teachers’ motivating styles (autonomy-supportive style and controlling style) and college students’ online SRL ability were positively correlated with college students’ online agentic engagement. Secondly, teachers’ autonomy-supportive style was positively correlated with college students’ online SRL ability, but the controlling style was negatively correlated with their online SRL ability. What’s more, college students’ online SRL ability, as a mediating factor, acted as a partial mediation between autonomy-supportive style and college students’ online agentic engagement, and there was a suppressing effect of college students’ SRL ability between teachers’ controlling style and college students’ agentic engagement. The results imply that teachers should choose motivating styles appropriately based on students’ online learning characteristics and content, and college students should develop online SRL ability to improve their agentic engagement and ultimately achieve good online learning effectiveness.
On the integration of Ito equations with a random or a W-symmetry
Authors: Gaeta G.
Published: December 2023

Symmetries can be used to integrate scalar Ito equation – or reduce systems of such equations – by the Kozlov substitution, i.e. passing to symmetry adapted coordinates. While the theory is well established for so called deterministic standard symmetries (the class originally studied by Kozlov), some points need clarification for so called random standard symmetries and W-symmetries. This paper is devoted to such clarification; in particular we note that the theory naturally calls, for these classes of symmetries, to also consider generalized Ito equations; and that while Kozlov theory is extended substantially unharmed for random standard symmetries, W-symmetries should be handled with great care, and cannot be used towards integration of stochastic equations, albeit they have different uses.
Asymptotic analysis of the higher-order lump in the Davey-Stewartson I equation
Authors: Guo Lijuan , Zhu Min , He Jingsong
Published: December 2023

In this paper, the long-time asymptotic dynamics of three types of the higher-order lump in the Davey-Stewartson I equation, namely the linear lump, triangular lump and quasi-diamond lump, are investigated. For large time, the linear lump splits into certain fundamental lumps arranged in a straight line, which are associated with root structures of the first component in used eigenvector. The triangular lump consists of certain fundamental lumps forming a triangular structure, which are described by the roots of a special Wronskian that is similar to Yablonskii-Vorob polynomial. The quasi-diamond lump comprises a diamond in the outer region and a triangular lump pattern in the inner region (if it exists), which are decided by the roots of a general Wronskain determinant. The minimum values of these lump hollows are dependent on time and approach zero when time goes to infinity. Our approximate lump patterns and true solutions show excellent agreement.
Measurement of droplet gravity-induced mechanical force by optofluidic microbottle resonator with lever model
Authors: Wang Zijie , Zhang Xiaobei , Zhang Qi , Yang Yong , Yu Yang , Wang Yang , Wang Tingyun
Published: December 2023

Whispering gallery mode resonators provide an intriguing platform for precision measurement due to their high responsivity and low detection limit. Here, we propose and demonstrate an optofluidic microbottle resonator (OFMBR) that is utilized to measure droplet gravity-induced mechanical force, realized by establishing a lever model between tapered fiber and OFMBR. The mechanical force can be amplified by adjusting the ratio of the load arm to the effort arm of the lever, which is validated by theoretical simulation. The evolved mechanical force deforms OFMBR morphology and enhances light scattering, resulting in mixed variations in the transmission spectrum, including resonance wavelength, mode linewidth, and signal intensity. Experimentally, the mechanical force is first measured by monitoring resonance wavelength shift, and a responsivity of −56 pm/mN is obtained within the range of 0–0.2 mN. Furthermore, to monitor the mixed variations in the transmission spectrum and obtain the actual mechanical force directly, the optical barcode method is utilized to simultaneously monitor the variations of multimode features. The arbitrary unknown mechanical force is determined by the cross correlation function, and the measurement resolution is about 5 µN. Our scheme provides a thread for characterizing the liquid properties and investigating the dynamics at solid–liquid interfaces.
Coherent dispersion effects in 2D and 3D high-intensity beams
Authors: Yuan Yao-shuo , Franchetti Giuliano
Published: December 2023

Both space charge and dispersion have an effect on high-intensity beams in circular accelerators or transport sections with bending magnets and may lead to emittance growth and beam loss. In this paper, we present an investigation of the combined effect of dispersion and space charge on two-dimensional beams deepening the understanding of the 120° dispersion-induced instability. We also investigate the 90° envelope instability, which in the absence of the dispersion, mixes the confluent and parametric resonances. We show here that the presence of dispersion and high intensity breaks the overlapping and separates the two resonances. Furthermore, we study the beam dynamics of three-dimensional bunched beams and find the surprising result that the synchrotron motion can split the dispersion mode into two equally separated “sideband” modes according to the beam intensity and synchrotron frequency.
Prior-free mixed speckle simplex separation strategy for multi-object imaging through thin scattering media beyond the optical memory effect
Authors: Wei Yi , Guo Enlai , Zhao Yan , Mu Dan , Bai Lianfa , Han Jing
Published: December 2023

The optical technique of imaging through scattering media based on the optical memory effect (OME) sustains a limited field-of-view (FOV). Therefore, a prior-free imaging method is proposed to reconstruct multiple objects through the scattering media beyond the OME range. Based on the mixed speckle simplex separation strategy designed in this method, separating speckles of sub-objects is simplified as seeking the vertices of the mixed speckle simplex. An effective initial analysis of the mixed speckle simplex constructed by random intensity modulation is provided by vertex component analysis. The exact speckles of sub-objects are then separated by the specially designed non-negative matrix factorization algorithm. The multiple hidden objects can be recovered from the separated speckles respectively. The feasibility and imaging effects of the proposed method have been demonstrated via experiments. Multi-object imaging through the scattering media beyond at least four times the OME range has been realized. This work effectively advances speckle separation strategies to enlarge the limited FOV for imaging through scattering media.
Effect of drainage on antibubble collapse
Authors: Liu Ziqi , An Ji , Chen Wu
Published: December 2023

Antibubbles are a special spherical structure generated in liquids surrounded by a thin air film. The collapse of antibubbles has been regarded as a feasible method for generating microbubbles. This paper demonstrates an experimental study on the antibubble collapse focusing on the effect of rupture time and location. With the help of a high-speed camera, the detailed collapse dynamics for different rupture times and locations was presented. The collapse velocity was found to vary significantly with the rupture time and location. An upgraded theoretical model was proposed to elucidate the effect of the air film thickness distribution due to drainage on the collapse velocity. This study should stimulate further investigation on the antibubble collapse, especially the size distribution of the generated microbubbles.
Preference of right-handed whistler modes and helicon discharge directionality due to plasma density gradients
Authors: Granetzny M. , Schmitz O. , Zepp M.
Published: December 2023

Whistlers are magnetized plasma waves in planetary magnetospheres. Bounded whistlers, known as helicons, can create high-density laboratory plasmas. We demonstrate reversal of the plasma discharge direction by changing either antenna helicity or magnetic field direction. Simulations reproduce these findings only in the presence of a radial density gradient. Inclusion of such a gradient in the wave equation gives rise to azimuthal shear currents, which for the first time consistently explains the preference of right- over left-handed whistlers and the discharge directionality in helicon plasmas.
Numerical analysis of the influence of hull-modulated inflow on unsteady force fluctuations and vortex dynamics of pump-jet propulsor
Authors: Xue Lin , Yang Yuze , Zou Donglin , Dong Xinguo , Ta Na , Rao Zhushi
Published: December 2023

The influence of the hull-modulated inflow on the propulsion performance of the propeller is related to the matching design of the propeller–hull system. In the present study, considering the working conditions of the pump-jet propulsor in uniform inflow and two types of hull-modulated inflow, based on improved delay detached eddy simulation, the influence of hull-modulated inflow on unsteady force fluctuations and vortex dynamics of pump-jet propulsor under design conditions is carried out. The results show that the hull-modulated inflow increases the propulsion efficiency of the pump-jet propulsor to varying degrees within the range of the calculated advance coefficient and has a significant influence on the frequency characteristics of the unsteady force spectra characteristics of each component of the pump-jet propulsor. It also shows changes in the magnitude characteristics, that is, the energy transfer process of an individual rotor blade from the stator blade passing frequency to other harmonics of the shaft rotation frequency, and the thrust spectrum of an individual stator blade presents broad-spectrum characteristics in the high-frequency range. Furthermore, the application of hull-modulated inflow directly affects the shape of the stator shedding vortex, causing some of the stator blade shedding vortices to separate early and aggravating its short-wave instability. More secondary vortices are induced to accelerate the instability of the rotor blade tip clearance vortex. The energy transfer mechanism from the rotor blade passing frequency and its harmonics to the broadband spectra appears in the wake field of the pump-jet propulsor.
Oscillatory electro-magneto-kinetics of confined-Stokes-second-problem micro-flows
Authors: Bera Neeladri Sekhar , Dhar Purbarun
Published: December 2023

We semi-analytically investigate the electro-magneto-hydrodynamics of time periodic electroosmotic flow of a Newtonian electrolyte through microchannels with oscillating boundaries, resembling a confined-Stokes-second-problem type system. Herein, a constant orthogonal magnetic field and a constant transverse electric field have been used along with the driving time periodic electric field to have better control over mixing in the microchannel or to augment the pumping. The Poisson–Boltzmann equation has been solved with Debye–Hückel linearization for the thin electric double layer to obtain the electric potential distribution. We determine the flow field for low Hartmann number (Ha) cases by the regular perturbation method. Furthermore, Laplace transformation has been used to solve the flow field for each order in the obtained perturbation series. We have obtained the solution of flow field up to O(Ha) and found an excellent match with the complete numerical solution for our range of Ha. The dependence of flow field on dimensionless parameters, such as Ha, electrokinetic number (M), and Womersley number (Wo), has been discussed thoroughly, where Ha and M are functions of the strength of applied magnetic field and transverse electric field, respectively, and Wo is the function of Debye length, kinematic viscosity, and frequency of the time periodic electric field. Interestingly, for large values Wo, we find wave like motion in the flow field, which induces vorticity as well as better mixing caliber. Additionally, we find that the interplay between Ha and M controls the mixing and modifies the flow rate according to the need. Various combinations of such parameters have been discussed to promote mixing as well as pumping for such strongly coupled microfluidic phenomena.
Lyapunov exponents and Lagrangian chaos suppression in compressible homogeneous isotropic turbulence
Authors: Yu Haijun , Fouxon Itzhak , Wang Jianchun , Li Xiangru , Yuan Li , Mao Shipeng , Mond Michael
Published: December 2023

We study Lyapunov exponents of tracers in compressible homogeneous isotropic turbulence at different turbulent Mach numbers Mt and Taylor-scale Reynolds numbers Reλ. We demonstrate that statistics of finite-time Lyapunov exponents have the same form as that in incompressible flow due to density-velocity coupling. The modulus of the smallest Lyapunov exponent λ3 provides the principal Lyapunov exponent of the time-reversed flow, which is usually wrong in a compressible flow. This exponent, along with the principal Lyapunov exponent λ1, determines all the exponents due to vanishing of the sum of all Lyapunov exponents. Numerical results by high-order schemes for solving the Navier–Stokes equations and tracking particles verify these theoretical predictions. We found that (1) the largest normalized Lyapunov exponent λ1τη, where τη is the Kolmogorov timescale, is a decreasing function of Mt. Its dependence on Reλ is weak when the driving force is solenoidal, while it is an increasing function of Reλ when the solenoidal and compressible forces are comparable. Similar facts hold for |λ3|, in contrast to well-studied short-correlated model; (2) the ratio of the first two Lyapunov exponents λ1/λ2 decreases with Reλ and is virtually independent of Mt for Mt≤1 in the case of solenoidal force but decreases as Mt increases when solenoidal and compressible forces are comparable; (3) for purely solenoidal force, λ1:λ2:λ3≈4:1:−5 for Reλ>80, which is consistent with incompressible turbulence studies; and (4) the ratio of dilation-to-vorticity is a more suitable parameter to characterize Lyapunov exponents than Mt.
How to extract kinetic information from Tafel analysis in electrocatalysis
Authors: Wu Weixing , Lu Qian , Li Guangchao , Wang Ying
Published: December 2023

Electrocatalysis has become increasingly attractive in aiding transformation to green chemical industries. Proper evaluation and in-depth understanding of electrocatalysts are critical to designing high-performance electrocatalysis systems. Tafel analysis is thus of great importance as it allows reliable performance comparison among different reports and provides insight into the reaction mechanism. This Tutorial discusses the Tafel analysis from experimental and theoretical perspectives. The principle of the Tafel analysis is revisited, and the procedure of mechanism investigation based on the Tafel analysis is included.
Toward understanding the mechanism of water dynamical onset on the material interfaces
Authors: Jin Tan , Zhang Qiang , Zhuang Wei
Published: December 2023

Interfacial water is ubiquitous on Earth, playing a crucial role in biology, chemistry, physics, materials science, and environmental science. Multiscale, hierarchical water motions on the surface of different materials under different conditions (temperature, hydration extent, pressure, etc.) and the coupling of this motion with the substrate/solute dynamics and the influence of these couplings on the material functions are complex, long lasting, interdisciplinary research topics. We herein focus on the coupling between the picosecond dynamical onset of substrates and their surface water at temperatures lower than the freezing point (273 K) and discuss the recent progress in the study of its molecular mechanisms.
Further extension of the Madrid-2019 force field: Parametrization of nitrate (NO3−) and ammonium (NH4+) ions
Authors: Trejos Víctor M. , de Lucas Marcos , Vega Carlos , Blazquez Samuel , Gámez Francisco
Published: December 2023

The importance of nitrate and ammonium salts both in the environment and in biological processes cannot be questioned. In this work, using the TIP4P/2005 water model, aqueous solutions of nitrate and ammonium electrolytes are parametrized using scaled charges while keeping a rigid structure and nonpolarizable charge distributions. The models are optimized by systematically testing a set of properties for twelve electrolytes—eight nitrate and four ammonium salts—thus, enlarging the number of potential chemical species encompassed within the Madrid-2019 force field for ions. The capacity of the force field for predicting densities, ion–ion and ion–solvent structures, and transport properties of the solutions comprised by the trial batch of salts was tested and discussed. Both the dependence of the densities with the salt concentration and the solution structure were nicely reproduced by the models in the whole concentration range without any trace of precipitating events and with improved accuracy in comparison with recently reported models, while the agreement of the simulated transport properties with experimental data ranges from good to reasonable, depending on the ion/counterion pair. These scaled charge models might be considered as force fields embodying a reasonable compromise between exactness and general applicability and also as an important step in the development of accurate models for polyatomic ions.
Aerodynamic mechanism of a combined buffer hood for mitigating micro-pressure waves at the 400 km/h high-speed railway tunnel portal
Authors: Li Guo-Zhi , Ye Xin , Deng E , Yang Wei-Chao , Ni Yi-Qing , He Hong , Ao Wai-Kei
Published: December 2023

As high-speed trains exceed 400 km/h, tunnel aerodynamics pose significant challenges. The hat oblique tunnel buffer hood with enlarged cross section and ventilation windows (HEW) is a promising solution to mitigate micro-pressure waves (MPWs). However, there is limited research on HEW ventilation window configurations. Thus, field measurements and numerical simulations were conducted using the slip grid technique and an improved delayed eddy simulation turbulence model, with validation against field data. The study investigated the effects of aperture rate and ventilation window arrangement, analyzing the initial compression wave, pressure gradient, MPW, and flow field in the tunnel buffer hood under various ventilation window setups. Findings emphasize that increasing the aperture rate or placing ventilation windows near the tunnel entrance reduces MPWs when a high-speed train enters the buffer hood. However, it intensifies MPWs when the train transitions from the buffer hood to the tunnel. Optimal MPW mitigation is achieved with approximately 15% aperture rate and a ventilation window distance from the slope end of 0.3–0.4 times the enlarged cross section length. Double ventilation windows outperform single or three windows in MPW reduction, with longitudinally arranged windows at the top facilitating more efficient high-pressure air escape compared to circumferential windows.
Topological insulator photodetectors in HOT infrared detector family
Authors: Rogalski A.
Published: December 2023

The past decade witnessed the emergence of a new generation of room-temperature infrared detectors based on low-dimensional solids. Among these are topological insulating materials. The present work aims to evaluate this class of photodetectors in the so-called high-temperature infrared (high operating temperature) photodetector family. Their performance, such as current responsivity and detectivity, are compared with available HgCdTe photodiodes, interband quantum cascade photodetectors, colloidal quantum dot detectors, and two-dimensional transition metal dichalcogenides.
Flow-induced response and wake characteristics of a flexible splitter plate attached to a circular cylinder in laminar flow
Authors: Zhu Hongjun , Chen Quanyu , Tang Tao , Alam Md. Mahbub , Zhou Tongming , Zhong Jiawen
Published: December 2023

This paper reported the numerical results of the flow past a flexible splitter plate attached to the rear of a rigid circular cylinder at a low Reynolds number of 160. The finite-volume method (FVM) in OpenFOAM-9 and the finite-element method (FEM) in deal.ii are utilized to solve the fluid and solid domains of the fluid–structure interaction (FSI) issue, respectively. The effects of the plate length L/D and normalized Young's modulus E* are examined. According to the equilibrium position and bending deformation order, five response modes are identified, including the symmetry-I, symmetry-II, symmetry-III, bifurcation-I, and bifurcation-II. The amplitude of the plate-tip is enhanced as the vortex shedding frequency approaches the natural frequency. Nevertheless, the bifurcation is observed between the symmetry-I and symmetry-II modes, where the vibration amplitude sharply drops. The number of local vortices occurring along the surface of flexible plate increases with the plate length, leading to more local negative pressure regions. Consequently, the higher mode response is excited. The greater shear stress occurs at the position of small curvature radius during the plate deformation. The 2S (a pair of vortices is alternately shed per cycle) vortex shedding mode is recognized in most cases. In contrast, the P + S (a pair of vortices shedding from one side and a single vortex shedding from the other side) mode is observed in the bifurcation-II mode with a relatively large amplitude. Due to the deflection, the wake flow becomes asymmetrical with a significant elongation of the recirculation region. Four interaction behaviors between the boundary layers and the plate are identified. The significant reduction of hydrodynamic forces is achieved when the flexible plate experiences the bifurcation.