bluuebunny/crossref_metadata_2025 huggingface dataset:
Stroke‐Seg: A deep learning‐based framework for chinese stroke segmentation
Authors: Gong Xinyu , Bai Zeyang , Nie Haitao , Xie Bin
Published: October 2024

Chinese stroke segmentation is a crucial and challenging task for various downstream applications such as font generation, aesthetic evaluation etc. Conventional semantic segmentation techniques typically face difficulties in accurately segmenting strokes, as intersection regions in Chinese characters can belong to multiple strokes simultaneously, and these approaches often lack a holistic understanding of character composition. This paper proposes a character stroke segmentation framework named Stroke‐Seg that integrates with various semantic segmentation architectures, demonstrating adaptability to different backbone networks to tackle the above tasks. A multi‐label output strategy is proposed to effectively classify strokes in intersection areas, overcoming the limitations of traditional semantic segmentation approaches. Additionally, a prior knowledge vector is incorporated into the input layer to provide character‐specific information on stroke composition, enhancing the ability of the framework to precisely identify and segment strokes. The effectiveness of the proposed framework is demonstrated through evaluations of a comprehensive dataset (brush calligraphy stroke segmentation dataset). Evaluations show that the proposed framework significantly improves the capability of semantic segmentation networks, achieving a remarkable improvement of up to 19.9% in the true stroke rate, compared to traditional stroke segmentation techniques. The Stroke‐Seg framework integrated with TransUNet demonstrates its high performance with an impressive 98.2% true stroke rate. Furthermore, the proposed framework combined with FCN still achieves good performance while consuming the least amount of computational resources and memory, demonstrating its potential for lightweight design.
A loudspeaker-driven clarinet for educational purpose
Authors: Penelet Guillaume , Ablitzer Frédéric , Dalmont Jean-Pierre
Published: October 2024

This paper describes a toy device, namely an electroacoustic clarinet, which was designed for educational purposes. It consists of a loudspeaker connected through a cavity to a duct drilled with several side holes. Unlike what happens in a clarinet where the emitted sound is caused by the motion of a reed and the blowing of a musician, the present system is excited by the loudspeaker through a positive feedback mechanism giving rise to self-oscillations. This feedback is achieved by placing a microphone in the cavity, and connecting it to the loudspeaker through an audio amplifier. It is shown that, by adjusting the gain of the amplifier and by opening/closing the side holes to control the pitch of the emitted sound, the system can spontaneously play all the notes of a scale. The dynamics of the system beyond the threshold of self-oscillations is also studied both experimentally and theoretically. This simple system can be easily reproduced with minimum equipment and it may have some merits for educational purpose, because its understanding requires some basic knowledge of electroacoustics, guided wave theory and nonlinear dynamics.
Utilizing mineral sequestration technology for enhanced performance of concrete containing basic oxygen furnace slag
Authors: Omarova Zhaniya , Ualiyev Dulat , Shon Chang-Seon , Zhang Dichuan , Kim Jong Ryeol
Published: October 2024

Basic oxygen furnace slag (BOFS) is a widely available by product of the steel-making industry that poses high interest for scientists in various fields. The carbon capture potential of BOFS is proven to be high. However, its further uses are actively investigated. BOFS is particularly attractive as a construction material due to its hydraulic reactivity and good strength, making it suitable for use as binding material and aggregate in concrete. However, it has a major drawback - unstable compounds that lead to material deterioration caused by volumetric expansion. Most of the research in the field focuses on the processing of BOFS in laboratory or industrial settings to eliminate the expensive products inside the slag and make it more durable. The suitability of using mineral sequestration technology instead of artificially accelerated carbonation has not yet been studied well. This research aimed to identify the main properties of the mortar mixes containing BOFS that underwent mineral sequestration over a long period to assess the technology’s feasibility. The correlation with quantitative data from thermogravimetric analysis (TGA) was also identified. Based on test results, the correlation between aging conditions and CO2 uptake was established, indicating that stockpiled and wet/dry cycle conditions were the most optimal aging methods for BOFS to achieve the highest carbonation (4.15-5.15%), hence the maximum stabilization degree of aggregates.
Evaluating the influence of convective heat transfer coefficient on the carbon footprint of a service building in Morocco
Authors: Idouanaou Abdessamad , Malha Mustapha , Bah Abdellah
Published: October 2024

This study examines how the convective heat transfer coefficient impacts the carbon footprint of a service building situated in Morocco. This coefficient is pivotal in shaping the thermal efficiency of buildings, influencing energy consumption and environmental impact. Through simulations and analyses, we evaluate the extent to which variations in this coefficient affect overall energy efficiency and carbon emissions. Our analysis, based on specific climate data for Morocco and detailed architectural and operational parameters of a typical service building, reveals significant annual deviations. Heating energy fluctuates by up to ±48%, and cooling energy varies by up to ±32%. Furthermore, our findings demonstrate that the carbon footprint of electricity consumption for heating and cooling can vary by as much as ±31% of total CO2 emissions annually. Optimizing the convective heat transfer coefficient emerges as a critical strategy for reducing the carbon footprint, underscoring its importance in sustainable building design. These results offer valuable insights for architects, engineers, and policymakers seeking to enhance building performance and minimize environmental impact within the unique climate conditions of Morocco.
Building vulnerability assessment on an urban scale: A case study on heavy rainfall events
Authors: Rosin Julia , Vetter Joanna Zarah , Neuhaeuser Stefan , Stolz Alexander
Published: October 2024

This paper presents a semi-automated approach for assessing building vulnerability on an urban scale, specifically focusing on floods and heavy rainfall events. The method involves three steps: categorization of buildings using open geodata, development of parametric building models for each category, and probabilistic analysis to generate fragility curves. To overcome the challenge of analyzing individual buildings in a large area, generalized models based on building categories are utilized, reducing computational effort but introducing uncertainties. Probabilistic analyses are conducted by adjusting simulation parameters to address these uncertainties. The approach is applied to a reference area in Berlin as a case study. The results provide valuable insights into the vulnerability of individual buildings within different categories. This research contributes to the field of the vulnerability assessment of buildings by offering a practical and efficient method applicable at an urban scale. It enables informed decisionmaking and the development of risk reduction strategies.
BIM implementation in the middle east construction: Evaluating the prospects and challenges
Authors: Suleiman Akram , Asaad Samaher
Published: October 2024

This research explores the potential benefits and challenges associated with the implementation of Building Information Modelling (BIM), a rapidly evolving global trend, within the construction industry of the Middle East. The study is underpinned by a comprehensive literature review on the global and Middle Eastern usage of BIM. A methodical empirical survey was employed to collect quantitative data, comparing the perspectives of Clients, Contractors, and Consultants. Key impediments to BIM adoption in the Middle East were identified as a scarcity of BIM-skilled subcontractors, the lack of industry standards, substantial initial costs, and organizational structures that do not support BIM. On the other hand, the advantages of BIM include improved construction planning, enhanced project quality, an elevated organizational image, and streamlined communication. The study provides crucial recommendations for local governments, policymakers, construction companies, and stakeholders to encourage comprehensive BIM adoption and its utilization in construction projects, while also discussing the practical implications of the findings.
Unexpected observations of the heavy-ion fusion excitation function above the Coulomb barrier
Authors: Watwood Nate , Jiang Cheng Lie , Henning Walter , Hoffman Calem , Kay Ben
Published: October 2024

Two unexpected behaviors have been observed in heavy-ion fusion excitation functions at energies above the Coulomb barrier. The first behavior is observed in overlapping excitation spectra. Fusion excitation functions σ(E) that have different entrance channels but fuse to the same compound nucleus appear to overlap in the energy domain above the barrier. The overlap emerges after scaling the center of mass energy of each excitation function by a constant scaling factor, SF. The second behaviour stems from the structure of the fusion excitation curve. Contrary to descriptions from coupled-channels or other model calculations, heavy-ion fusion excitation functions are not smooth near and above the Coulomb barrier. There appears to be weak but noticeable oscillations or structures within the excitation functions that can be observed clearly in the representation d(σE)/dE and in comparison with theoretical calculations σ(E) - σth(E). Moreover, the corresponding d(σE)/dE spectra for systems that form the same compound nucleus also overlap well in this energy range, including their fine structures, but the uncertainty is large. It appears the two behaviors are correlated and the reasoning behind these behaviors are yet unknown, but may be due to the compound-channel effect.
Reaction dynamics of proton drip-line nuclei at energies around the Coulomb barrier
Authors: Chang C. , Yang L. , Lin C. J. , Yamaguchi H. , Ma N. R. , Hayakawa S. , Wen P. W. , Jia H. M. , Luo T. P. , Yin C. , Huang Z. J. , Duan H. R. , Zhu S. X. , Wang H. R. , Fan Z. R. , Li H. Y. , Fu L. Y.
Published: October 2024

This work briefly introduces our recent studies on reactions induced by proton drip-line nuclei, 8B and 17F, at energies around the Coulomb barrier. Using detector arrays with large solid-angle coverage, the complete kinematics measurements were performed for systems of 8B+120Sn and 17F+58Ni. For the 8B+120Sn, the coincident measurement of the breakup fragments was achieved for the first time for a proton-halo nuclear system. The correlations between the breakup fragments reveal that the prompt breakup occurring on the outgoing trajectory dominates the breakup dynamics of 8B. For 17F+58Ni, the complete reaction channel information, such as quasi-elastic scattering, breakup and total fusion, was derived for the first time. An enhancement of the fusion cross section of 17F+58Ni was observed at the energy below the Coulomb barrier. Theoretical calculations indicate that this phenomenon is mainly due to the couplings to the continuum states. Moreover, diﬀerent direct reaction dynamics were found in 8B and 17F systems, suggesting the influence of proton-halo structure on the reaction dynamics.
Measurement of the 27Al(p, α)24Mg fusion reaction at astrophysical energies via the Trojan Horse Method
Authors: La Cognata M. , Palmerini S. , Adsley P. , Hammache F. , Di Pietro A. , Figuera P. , Dell ’Agli F. , Alba R. , Cherubini S. , Guardo G.L. , Gulino M. , Lamia L. , Lattuada D. , Maiolino C. , Oliva A. , Pizzone R.G. , Prajapati P. , Rapisarda G.G. , Romano S. , Santonocito D. , Spartà R. , Sergi M.L. , Tumino A. , Ventura P.
Published: October 2024

In astrophysics, the abundance of 26Al is essential for understanding nucleosynthesis in the Milky Way and Galactic core-collapse supernovae rates. Detection methods involve γ-ray lines and comparing 26Mg overabundance with the common Mg isotope in meteorites. Therefore, stable isotopes 27Al and 24Mg play a crucial role and the MgAl cycle aﬀecting aluminum and magnesium production has to be carefully studied. Recent surveys reveal complexities in stellar populations whose understanding may also benefit from better constraining the closure of the MgAl cycle. The 27Al(p, α)24Mg fusion reaction, a key 27Al destruction channel, is central to these scenarios. Due to uncertainties, the Trojan Horse Method is applied, allowing high-precision spectroscopy on the compound nucleus 28Si. It reveals crucial fusion cross section information in the astrophysically relevant energy range. The indirect measurement by means of the 2H(27Al,α24Mg)n process made it possible to assess the contribution of the 84.3 keV resonance and to set upper limits on nearby resonances. This study evaluates the THM recommended rate’s impact on intermediate-mass asymptotic giant branch stars, showing a notable increase in surface aluminum abundance at lower masses due to fusion cross section modification, while 24Mg remains largely unaﬀected.
Connection between nuclear structure, dissipation, and time in fission data
Authors: Caamaño M. , Ramos D. , Fernández D. , Mantovani G. , Farget F. , Rodríguez-Tajes C. , Lemasson A. , Rejmund M. , Schmitt C. , Ackermann D. , Álvarez-Pol H. , Audouin L. , Benlliure J. , Biswas S. , Casarejos E. , Clement E. , Cortina D. , Delaune O. , Derkx X. , Dijon A. , Doré D. , Durand D. , Frankland J. D. , Fernández-Domínguez B. , de France G. , Fregeau M. O. , Galaviz D. , Galiana-Baldó E. , Heinz A. , Henriques A. , Jacquot B. , Jurado B. , Kim Y. H. , Morfouace P. , Paradela C. , Piot J. , Ralet D. , Roger T. , Salsac M. D. , Teubig P. , Tsekhanovich I.
Published: October 2024

Nuclear fission is still one of the most complex physical processes due to the interplay between macroscopic and microscopic nuclear properties that decide the output. An example of this coupling is the presence of nuclear dissipation as an important ingredient that contributes to drive the dynamics and has a clear impact on the time of the process. However, different theoretical interpretations and scarce experimental data make it poorly understood. At low excitation energy, the relative yields of fragments even and odd atomic numbers show a clear difference, which can be quantified with the so-called even-odd effect. This seemingly mundane property can be used to obtain information about the energy dissipated during the process and the role of structure in its dynamics.

In this paper, the study of the even-odd effect for elasticand transfer-induced fission data is discussed. A clear connection with particular fragment shells and the dissipation energy is found, as detailed in Ref. [1]. In addition, preliminary results from quasi-fission data show the formation of a relatively large even-odd effect, which suggests a process with low dissipation mainly consisting in the exchange of nucleon pairs.
Fission Fragment Angular Momenta: Generation and Observation
Authors: Randrup Jørgen , Døssing Thomas , Vogt Ramona
Published: October 2024

The fission fragment angular momenta can generally be expressed in terms of the six normal modes of rotation for the dinucleus and different models populate those modes to different degrees reflecting the mechanisms involved. For the nucleon exchange mechanism, the characteristic time scales for the various modes are discussed, leading to the expectation that the wriggling mode is fully populated, while twisting is unlikely to play a major role; bending probably has some presence which increases with mass asymmetry. Subsequently it is discussed how information about the fragment spin directions can be determined by observation of E2 emissions in even-even nuclei. It is shown how the yield ratio Y (0°)/Y (90°) in a modern Wilhelmy-type experiment can reveal the degree of twisting, a measurement that could be readily carried out now. Furthermore, with a view towards the future when the required technology has been developed, it is illustrated how the relative role of positive modes (wriggling) and negative modes (bending and twisting) can be determined by measuring the opening angle between two E2 photons whose helicities are also identified.
Spontaneous fission half-life in Fm isotopes with nuclear energy density functional
Authors: Washiyama Kouhei
Published: October 2024

A microscopic description of fission dynamics is important to understand the decay properties of neutron-rich heavy nuclei that are relevant to r-process nucleosynthesis. To provide a reliable and efficient method to evaluate the spontaneous fission half-life, we develop a method, called the constrained Hartree– Fock–Bogoliubov (CHFB) plus local quasiparticle random-phase approximation (LQRPA), to include dynamical residual effects in the collective inertia. With the CHFB + LQRPA, we evaluate the collective potential and the collective inertia along a mass-symmetric fission path in Fm isotopes with the neutron numbers N = 158–164. The obtained LQRPA inertia is much larger than the cranking one that ignores dynamical residual effects and shows a remarkable variation along the fission path. We estimate the fission half-life of the Fm isotopes using the action integral with the obtained collective potential and inertia. A large difference between the fission half-lives obtained with the LQRPA inertia and with the cranking inertia is observed. This indicates the importance of evaluating the collective inertia for estimating the fission half-life.
Interplay of breakup and fusion in near-barrier collisions of weakly-bound nuclides
Authors: Simpson E. C. , Cook K. J. , Bezzina L. T. , Carter I. P. , Dasgupta M. , Hinde D. J.
Published: October 2024

Light, weakly-bound nuclides such as 6,7Li and 9Be exhibit a diverse range of near-barrier reaction phenomena. Complete fusion is found to be suppressed by up to 35% with respect to barrier-passing model calculations. Their weak binding leads to significant breakup through excitation of the continuum, but also through production of weakly-bound or unbound neighbouring nuclides via nucleon transfer. Such systems also exhibit large yields of incomplete fusion, which is correlated empirically with cluster breakup thresholds for these stable nuclides.

Disentangling these reaction phenomena and their complex interplay is one of the most interesting challenges in near-barrier reaction dynamics. Here we briefly review our recent progress in understanding the interplay between breakup and fusion. These results strongly suggest that the dominant mechanism leading to incomplete fusion and the suppression of complete fusion is direct capture of the projectile cluster constituents by the target nucleus, rather than requiring projectile breakup prior to fusion.
Implication of compact configuration of hexadecapole deformed actinides in the synthesis of superheavy nuclei
Authors: Jain Shivani , Sharma Harshit , Kumar Raj , Sharma Manoj K.
Published: October 2024

The quadrupole (β2) deformed targets in the actinide region are found to be of great relevance in the production of superheavy nuclei (SHN), in the compact fusion mechanism. Recently, the application of “elongated” and “compact” configurations of pear-shape octupole (up to β3) deformed nuclei was found to play a significant role in the fusion-fission dynamics of heavy-ion induced reactions. In the present work, we intend to explore the relevance of higher-order deformed (up to β4) actinides and their compact configuration in the production cross-section as well as de-excitation of SHN (dynamics of 48Ca + 238U →286Cn∗ → A1 + A2 reaction). For the above analysis, we have calculated σER within the framework of dynamical cluster-decay model developed on the basis of quantum mechanical fragmentation theory, which has been extended with the inclusion of deformations up to β4 and corresponding compact optimum orientation. Besides, on the basis of this theory, the fragmentation structure of 286Cn∗ superheavy nucleus is examined in terms of fragmentation potential (Vη) and preformation probability (P0) as a function of fragment mass number.
Development of a mosaic-type array formed by Si photodiodes for charged-particle detection in heavy-ion collisions
Authors: Li Jiatai , Imai Nobuaki , Yokoyama Rin , Kojima Reiko , Michimasa Shin’ichiro , Chillery Thomas , Hanai Shutaro , Kitamura Noritaka , Saito Takeshi , Suzuki Daisuke , Nishimura Daiki , Takada Eiichi , Sakaguchi Satoshi , Xiao Zhigang
Published: October 2024

Silicon (Si) detectors find widespread application in heavy-ion collisions. In order to achieve a position-sensitive charged-particle detection with a relatively low cost, we have developed a mosaic-type array based on off-the-shelf Si photodiodes (Hamamatsu S13955-01). Its high modularity allows one to modify the geometric configuration of the array according to specific experimental requirements. In this contribution, characteristics of the photodiode tested with α source and experimental results of the α-decay spectroscopy are presented.
Measurement of the Radiative-Decay Probability of the Hoyle State
Authors: Sakanashi Kosuke , Kawabata Takahiro , Furuno Tatsuya , Tamii Atsushi , Niina Rei , Okamoto Shintaro , Ito Masatoshi , Adachi Satoshi , Akimune Hidetoshi , Matsuda Yohei , Kubono Shigeru , Aogaki Soichiro , Soöderstroöm Pär-Anders , Teodora Madgearu , Pai Haridas , Cuciuc Mihai , Tescov Dmitry , Borcea Ruxandra , Turturica Andrei , Mihai Constantin , Neacse Catalin
Published: October 2024

The radiative-decay probability of the Hoyle state is actually controversial because new data which contradicts the currently adopted value has been recently reported. In this work, we performed the new reliable measurement of the radiative-decay probability of the Hoyle state. We successfully obtained 40 triplecoincidence events of scattered α particles, recoil 12C, and emitted γ rays for the first time. Further analysis will determine the radiative-decay probability, and puzzle over the radiative-decay probability.
Analysis of the kinetic energy from fission fragments using dynamical model
Authors: Takagi S. , Aritomo Y. , Hirose K. , Nishio K.
Published: October 2024

It is known that the kinetic energy of individual fragments for fission of actinides is constant at about 100 MeV for light fragments and that for heavy fragments decreases with mass number. The kinetic energy is, for example, important for evaluating the prompt-neutron spectrum in the laboratory system. However, its theoretical study has not been attempted in detail so far. We have calculated them in thermal-neutron induced fission of 235U using the dynamical model, considering the Coulomb energy at the scission point and the prescission kinetic energy. The calculated results reproduce the experimental data. It is found that the pre-scission kinetic energy has about 5% contribution in the kinetic energy.
High Throughput and High Quality Laser Ablation, Texturing Techniques, Light Manipulation and Control in Industrial Processes with Ultra-Short Pulsed Lasers
Authors: Neuenschwander B. , Jaeggi B. , Remund S. M. , Maehne T.
Published: October 2024

This lecture deals with industrial application of ultrashort laser pulses. Part I discusses process efficiency, its optimization and effects limiting the power scale up whereas strategies to achieve high throughput are presented in Part II.
Ultra-Short Pulse Generation at 914 nm from a CW laser source
Authors: Florentin Raphaël , Viry Arnaud , Robin Thierry , Corre Kilian Le , Santarelli Giorgio , Georges Thierry , Gilles Hervé , Girard Sylvain , Laroche Mathieu
Published: October 2024

We present an all-PM fiber laser system seeded by a single-frequency CW laser source generating 230fs pulses at 914nm with a tunable repetition rate between 5 and 20 MHz. Ultra-short pulse train was achieved using a Mach-Zehnder modulator for pulse carving, Nd-doped fiber amplifiers and a Mamyshev regenerator.
High efficiency diode-pumped femtosecond-laser-written waveguide lasers based on Pr:LiLuF4
Authors: Baiocco Davide , Lopez-Quintas Ignacio , Aldana Javier Rodriguez Vazquez de , Tonelli Mauro , Tredicucci Alessandro
Published: October 2024

We present high-efficiency, diode-pumped waveguide lasers fabricated in Pr:LiLuF4 by direct femtosecondlaser writing. We demonstrated bulk-level slope efficiencies at 604 nm and 721 nm, diode-pumped lasing at 523 nm, and TEM00 laser operation at 721 nm.
Waveguide-based optical parametric oscillator for coherent anti-Stokes Raman scattering
Authors: Gao Ming , Wallmeier Kristin , Fallnich Carsten
Published: October 2024

A Si3N4 waveguide-based optical parametric oscillator is presented that generates narrowband output pulses down to 1.44 nm and with up to 211 pJ pulse energy, allowing coherent Raman scattering spectroscopy and microscopy with sufficient spectral resolution and high contrast.
Various fiber optic microlenses fabricated using a large diameter splicing system
Authors: Matczak Szymon , Stachowiak Dorota , Soboń Grzegorz
Published: October 2024

We developed and fabricated various types of microlenses on optical fiber end facets using a large diameter splicing (LDS) system and analyzed the obtained beam profiles. Numerical simulations support our experimental results.
Optimization of femtosecond fiber laser pulses with selected machine-learning algorithms
Authors: Kwaśny Alicja , Krakowski Mikołaj , Soboń Grzegorz
Published: October 2024

We investigate the possibility of optimization of ultrashort laser pulses by spectral phase modulation using machine learning algorithms. We compare the efficiency of two algorithms: Grey Wolf Optimizer and Genetic Algorithm.
Efficient Resonant Waveguide Grating for High-Power Lasers in the 2-µm Wavelength Range
Authors: Boubekraoui Ayoub , Tomilov Sergei , Redkin Mykyta , Bashir Danish , Mourkioti Georgia , Mackenzie Jacob , Saraceno Clara J. , Graf Thomas , Ahmed Marwan Abdou
Published: October 2024

We present resonant waveguide-grating (RWG) tailored for lasers operating at the 2-µm wavelength range. Utilizing the RWG as a cavity mirror, generation of tunable narrow-bandwidth and linearly-polarized radiation from a Ho:YAG thin-disk laser was demonstrated.
Design, fabrication and characterization of a grating waveguide structure with embedded quantum wells based on the GaInP/AlGaInP platform
Authors: Leyzner Maxim , Gierss Peter , Ćutuk Ana , Currle Kai , Rühle Rebecca , Jetter Michael , Michler Peter , Graf Thomas , Ahmed Marwan Abdou
Published: October 2024

We propose a grating waveguide structure with embedded quantum wells that shows potential for improving the cooling scheme for red-emitting VECSELs. The reflectivity map, the internal field distribution and the transmission spectra of our recently fabricated structures are presented.
Single hollow-core fiber for the guidance of IR (1030 nm) and visible (515 nm) ultrashort pulsed laser radiations
Authors: Chena Bowen , Kühlthau Tim , Kleema Götz , Graf Thomas , Ahmed Marwan Abdou
Published: October 2024

We present in this contribution a single large-mode area inhibited-coupling hollow-core fiber for guiding laser beam at a wavelength of 1030 nm and its second harmonic at 515 nm with confinement losses below 30 dB/km.
Thulium Holmium co-doped tunable fiber laser
Authors: Tofaili Hussein , Grande Adrian , Jubera Veronique , Cormier Eric
Published: October 2024

We report a Tm-Ho co-doped fiber laser with continuous tunability between 1965-2120 nm thanks to a rotating diffraction grating in the laser cavity. It delivers an OSNR of over 60 dB at the central wavelength 2060 nm. The output is linearly polarized with a 0.7% RMS instability. This laser is tailored for spectroscopy of Ho-doped materials.
Pedestal-cladding-pumped holmium fiber laser optimization using an analytical model
Authors: Pokorný Jan , Aubrecht Jan , Grábner Martin , Peterka Pavel
Published: October 2024

An analytical model of holmium-doped fiber laser is used to calculate optimal fiber length, pump wavelength and signal wavelength under in-band pumping conditions while considering fiber losses. The calculations show the advantages of a new type of pedestal-cladding-pumped fiber.
Gain-Managed Nonlinear Amplification in Erbium-Doped Fibers
Authors: Krakowski Mikołaj , Bogusławski Jakub , Kwaśny Alicja , Soboń Grzegorz
Published: October 2024

This experiment aimed to characterize Gain-Managed Nonlinear amplification (GMN) in Erbium-doped fibers. This effect has so far been presented in Ytterbium-doped fibers and only simulated on Erbium-doped fibers.
Statistical analysis of a self-starting linear Mamyshev oscillator with two symmetric Tm-doped fiber gain sections
Authors: Kirsch Dennis C. , Likhachev Mikhail E. , Aleshkina Svetlana S. , Yashkov Mikhail V. , Chernysheva Maria
Published: October 2024

An innovative concept to achieve a self-starting, all-fibre and all-normal dispersion Mamyshev oscillator for the 1.9 μm wavelength domain is explored. A machine-aided approach is chosen to investigate systematically the constrictions between filter offset, output coupling ratio and pump power.
High Average Power High-Harmonic EUV Sources and High Performance Imaging at the Nanoscale
Authors: Limpert Jens , Rothhardt Jan
Published: October 2024

We will report about the development of fiber-laser-driven high harmonic sources with output power currently exceeding 10 mW. This exceptional performance, combined with structured illumination approaches, enables nanoscale imaging and mapping of the chemical composition of semiconductor- and biological samples at the nanoscale.
Modelocked Thin-Disk Laser Oscillator with 550 W of Average Output Power
Authors: Seidel Moritz , Lang Lukas , Phillips Christopher R. , Keller Ursula
Published: October 2024

We present an ultrafast thin-disk laser oscillator providing a record power of 550 W with 100-µJ, 852-fs pulses at a repetition rate of 5.5 MHz. This is enabled by a six-pass replicating-cavity multipass scheme and ion-implanted sapphire-bonded SESAMs.
High-power, µJ-class Kerr-lens mode-locked thin-disk oscillators at 2.1 µm
Authors: Tomilov Sergei , Redkin Mykyta , Wang Yicheng , Yao Weichao , Suzuki Anna , Hoffmann Martin , Saraceno Clara J.
Published: October 2024

We report on the development of 2.1-µm high-power Kerr-lens mode-locked thin-disk oscillator configurations based on Ho:YAG, reaching up to 29 W of output power and 1.74 µJ of pulse energy.
Highly sensitive multi-stage terahertz parametric upconversion detection based on RbTiOPO4 crystal
Authors: Ming Na , Fan Shuzhen , Zhang Xingyu , Chen Xiaohan , Cong Zhenhua , Liu Zhaojun , Li Dechun , Guo Quanxin , Guo Liyuan , Jiao Binzhe , Yuan Jiasheng , Wang Kaiyu , Liu Naichang
Published: October 2024

Highly sensitive terahertz frequency upconversion detection was demonstrated with a RbTiOPO4 crystal. The detectable THz frequency ranges were 3.6-4.0, and 5.4-5.7 THz. The minimum detectable terahertz energy at 5.6 THz was about 0.2 fJ.
Influence of intracavity-air loss on 946-nm Nd:YAG laser performance
Authors: Brock Isaac , Mackenzie Jacob I.
Published: October 2024

We report on the impact of humidity in a cryogenically cooled Nd:YAG laser operating at 946-nm. Performance degrades with increasing cavity length, which is attributed to absorption by water vapour, an additional intracavity loss.
Dynamic thermal analysis of pulsed blue diode pumped Ti:Sapphire amplifiers
Authors: Hug Daniel , Zeyen Manuel , Dax Andreas , Trisorio Alexandre , Carreto Romain , Südmeyer Thomas , Resan Bojan
Published: October 2024

We simulated the time-dependent temperature profiles inside a blue diode pumped Ti:Sapphire (Ti:Sa) laser amplifier for several different pulsed pump configurations using a discrete element method, including temperature-dependent thermal conductivity and specific heat capacity of Ti:Sa crystals. Furthermore, we calculated the resulting focal length of the thermal lenses using the optical path differences through the crystal.
Tunable emission of an external-cavity Yb:KGW monolithic solid-state laser
Authors: Cuenca Miguel , Ortega Angela E. , Maestre Haroldo
Published: October 2024

Tunable microchip/monolithic lasers are expected to show promising applications. In this work external cavity techniques are applied to a Yb:KGW monolithic laser achieving 35 nm tuning by balancing Nm and Np emission polarizations.
Alexandrite Lasers: Review of recent laser progress and developments for vegetation lidar
Authors: Damzen Michael J.
Published: October 2024

A review is made of recent progress in diode-pumped Alexandrite lasers as a high-power, tunable- wavelength source, and our advances in developing Alexandrite as a short-pulse, high-pulse-rate vegetation lidar source for satellite-based Earth Observation.
Power scaling of LED-pumped alexandrite: The road to high gain multipass amplifiers
Authors: Thellier Elio , Taleb Hussein , Le Blanc Catherine , Pichon Pierre , Druon Frédéric , Georges Patrick , Balembois François
Published: October 2024

Our experiment demonstrates that LED-pumping through luminescent concentrator enables sufficient pump power for viable alexandrite amplifier gain. In 10 passes we obtain a gain of 19 with 10 W output power, for 50 µs pulses at 20 Hz and 760 nm.
Autofocus and motion error compensation methods for gantry machine in ultra-precise laser machining applications
Authors: Piscalov Artur , Mikulis Giedrius , Rafanavicius Vytautas
Published: October 2024

Error compensation by applying motion control methods makes auto-focus easy and reliable in micro-machining applications. We present a method for dynamic roll and yaw compensation in gantry machines.
Sub-ps THz-Pulse-Driven Electro-Absorption Switching in Heterostructure Quantum Dots
Authors: Jutas Rokas , Gollner Claudia , Kreil Dominik , Dirin Dmitry N. , Boehme Simon C. , Baltuška Andrius , Kovalenko Maksym V. , Pugžlys Audrius
Published: October 2024

Free-space terahertz signal is encoded onto an optical signal probing the absorption of CdSe/CdS core/shell quantum dots, utilizing quantum-confined Stark effect. The demonstrated ultrafast electro-absorption modulation could support Tbit/s data rates with extinction ratio exceeding 6 dB. © 2024 The Authors.
1.3 W, super-octave-spanning Pulses at 2.3 μm from a Cr:ZnS Amplifier
Authors: Kimbaras Džiugas , Fuerbach Alexander , Liang Wei , Steinleitner Philipp , Gröbmeyer Sebastian , Karpowicz Nicholas , Krausz Ferenc , Weigel Alexander
Published: October 2024

We investigate spectral broadening in TiO2 seeded by > 2 W, τ0.5 = 26 fs, 23 MHz pulses from a Cr:ZnS amplifier. We generate pulses covering spectrum from 1.1 to 3.2 µm at the -20-dB level at 1.3 W.

© 2024 The Author(s)
Amplification of Long-Wave Infrared Pulses in a Multicolor Non-Collinearly Pumped OPCPA for High-Energy Output
Authors: Jutas Rokas , Roman Joris , Astrauskas Ignas , Imani Aref , Carpeggiani Paolo , Polynkin Pavel , Kaksis Edgar , Floery Tobias , Kolenda Jonas , Bartulevičius Tadas , Michailovas Kirilas , Michailovas Andrejus , Baltuška Andrius , Pugžlys Audrius
Published: October 2024

Non-collinearly-seeded, KTA-based NOPCPA is used to generate multicolor, angularly separated pump pulses above 2 μm wavelength. These multicolor pump channels are used to amplify LWIR pulses in a non-collinearly-pumped ZGP NOPCPA to sub-mJ level, with potential scalability beyond 10 mJ. © 2024 The Authors.
Generation of femtosecond pulse bursts at multiple-THz repetition rate by nonlinear self-compression in bulk KTP
Authors: Krook Christoffer Oxelmark , Pasiskevicius Valdas
Published: October 2024

A chirped 470 fs pulse at 1030 nm was used to generate a phonon-polariton wave in bulk KTP by optical rectification. Phase modulation of the pump by the polariton wave resulted in generation of a burst of 20 fs pulses.
Generation and 2D field imaging of THz vortex beams
Authors: Liu Yaqun , Pasiskevicius Valdas
Published: October 2024

Optical rectification along three-fold axis in zincblende-symmetry crystal is used to generate vector and scalar vortex beams in THz. 2D electro-optic imaging is used for frequency- resolved THz field amplitude and phase characterization.
Complementary correlation between surface microbubble and droplet shapes
Authors: Takahara Koji , Suzuki Satoru
Published: October 2024

Previous atomic force microscopy studies have suggested that surface micro- and nanobubbles exhibit a flat shape. In this study, we directly observed surface microbubbles formed in an NH3BH3 solution using an optical microscope. No flat microbubbles were observed. Instead, on an SiO2/Si substrate, we discovered a relationship where the sum of the contact angle of a microbubble and the contact angle of a droplet equaled ∼180°. This relationship allowed us to control the shape of surface microbubbles by manipulating the wettability of the surface and the surface tension of the liquid, similar to droplet control. We were able to produce almost perfectly spherical microbubbles. Conversely, on a Cu foil, this relationship did not hold, although we still observed the formation of nearly spherical microbubbles. In this scenario, the shape of microbubbles appeared to be influenced by contact line pinning.
On the study of proximity magnetism in van der Waals graphene/CuCrP2S6 heterostructure via the anomalous Hall effect
Authors: Dedkov Yuriy , Voloshina Elena
Published: October 2024

Recently, several experimental works have appeared in the literature where induced magnetism in single- and few-layer graphene (SL-gr and FL-gr) interfaced with layered van der Waals materials was investigated via the application of the anomalous Hall effect (AHE). In most of these works, it is suggested that the observation of the AHE in such systems can be explained by a magnetic exchange interaction appearing at the interface between graphene and the underlying magnetic insulator. Considering the recently studied FL-graphene/bulk-CuCrP2S6 system as an example, our careful and rigorous analysis of recent experimental and theoretical data presented in the literature shows that the claimed observation of the AHE and magnetic proximity effect in this system is not supported. Moreover, the theoretically calculated electronic structures of the studied system contain serious errors and flaws that cannot be considered as an accurate description of such an interface and cannot be taken as solid support for the proposed proximity effect.
A linearized hydrodynamic code for laser ablation and its application to laser pulse shaping for direct-drive fusion
Authors: Zheng Guannan , Tao Tao , Jia Qing , Li Jun , Yan Rui , Zheng Jian
Published: October 2024

One of the most harmful processes in inertial confinement fusion is Rayleigh–Taylor instability (RTI), and an efficient way to mitigate it is pulse shaping. However, because shaped laser pulses lead to unsteady ablation, it is insufficient to evaluate RTI based solely on the instability growth rate. Here, for better prediction of RTI during linear growth, hydrodynamic equations for laser ablation (including both balance and linearized perturbation equations) are solved numerically and used to optimize the laser pulse shape for direct-drive inertial confinement fusion. For given target conditions and laser energy, simulations show that a picket pulse before the main laser pulse can reduce RTI significantly, and it is clear that the reduction comes from two aspects: (i) the lower RTI seed due to rarefaction at the descending edge of the picket in the imprint stage and (ii) the smaller growth rate due to enhanced ablation velocity at the main pulse in the acceleration stage. It is found that the perturbed laser deposition in an underdense plasma also has a profound influence on RTI seeds in the imprint stage.
Voltage stability control strategy for DC microgrid based on adaptive virtual DC motor
Authors: Deng Yuefei , Quan Xinbo , Hu Wei , Fang Shilei , Xiang Huiming
Published: October 2024

The large-scale integration of distributed energy sources and power electronic devices results in the DC microgrid exhibiting significant low inertia and weak damping characteristics. This, in turn, leads to inevitable fluctuations in the DC bus voltage, which endanger the stable operation of the DC system. Energy storage devices can provide equivalent inertia. To enhance the inertia and response speed of the DC bus interface converter, this paper proposes a power allocation parameter adaptive virtual DC motor control strategy based on a hybrid energy storage unit. The strategy introduces power allocation control to regulate the energy storage converter on the basis of virtual inertia parameter adaptive control, thereby enabling the energy storage converter to simulate the inertia and damping characteristics of a DC generator. The small-signal stability of the system is analyzed by establishing a small-signal model of the photovoltaic energy storage system and utilizing the impedance ratio criterion. Finally, the proposed control strategy is validated through simulation. The results demonstrate that the strategy effectively mitigates the fluctuations in bus voltage under varying photovoltaic power and sudden load changes, ensures the power distribution in the hybrid energy storage system, and enhances the dynamic response of the system.
Research on trajectory tracking control method for agricultural robot permanent magnet synchronous motor servo system based on improved EMD threshold wavelet filtering
Authors: Shen Bo , Pan Junbing , Ning Dong , Wang Huan
Published: October 2024

In agricultural robots, trajectory tracking can be affected by disturbances such as road slopes or bumps, leading to sudden changes in path curvature and reduced control accuracy. To address this issue, we propose a servo motor drive control method based on an improved Empirical Mode Decomposition (EMD) threshold. A mathematical model integrating the drive and control of the servo motor is established, and the driving performance of the servo motor is analyzed. By detecting the speed and position of the servo motor, the specified three-phase current values for motor drive control are derived. The actual current of the motor is collected using Hall current sensors and denoised with an improved EMD threshold wavelet filtering method. Within the servo motor drive control model, the system calculates the difference between the given three-phase current values and the actual motor current, and this difference is then used to adjust the motor control via an input linear amplifier, ensuring integrated drive control. Simulation and experimental results show that the proposed trajectory tracking control method for the agricultural robot’s permanent magnet synchronous motor servo system exhibits high control accuracy, strong anti-interference ability, and good performance, making it more suitable for practical applications.
Bifurcate migration of neutrally buoyant particles in unilateral slippery channel flows
Authors: Tao Shi , Zhang Xilin , Wang Wenhao , Wang Liang , He Qing , Lin Yousheng
Published: October 2024

As an important technique for manipulating particles in fluid–solid channel flows, inertial focusing encourages the design of the channel geometry to enhance particle radial aggregation. Traditional methods typically use exquisite sheathes or elbows to create constricted flows, which ultimately increase flow resistance and lower fluid–solid separation efficiency. This paper presents a slippery wall modification technique that, by regulating the channel flows, is expected to induce nontrivial particle lateral migrations. More specifically, interface-resolved simulations are performed using the lattice Boltzmann method. A slip boundary condition is applied to the redesigned hydrophobic bottom wall. It is observed that the typical bifurcate migration, i.e., particles moving divergently toward the upper and lower equilibrium positions around a crucial location (CL), does not occur along the channel centerline. The CL is always below the centerline, and it decreases consistently with an increase in Kn or Re. By increasing Re, particles are prone to approach the channel centerline. With larger Kn, particles in the higher equilibrium position are affected in the same way, but their lower counterparts are drawn to the bottom wall.
On the dynamics of Rossby algebraic solitary waves induced by large-scale topography
Authors: Han Fengyun , Liu Quansheng , Yin Xiaojun , Zhang Ruigang
Published: October 2024

The study of atmospheric Rossby waves could provide a theoretical basis for weather forecasting systems. In this paper, the barotropic quasi-geostrophic model is used to discuss the nonlinear Rossby waves induced by large-scale topography under the β-plane approximation. Starting from the potential vorticity equation, the atmospheric area is divided into internal region and external region, and the perturbation expansions of the two equations are carried out by using the separate multi-scale perturbation method. The Benjamin–Ono equation describing the wave amplitude is obtained by matching solutions of the internal and external equations at the boundaries. The distributions of the perturbation stream function, the total stream function, and the vorticity are obtained. It is found that the algebraic solitary waves induced by large-scale topography do exist. Moreover, the amplitude of the nonlinear Rossby waves is affected along with the changes of topography.
The fracture propagation law of axially symmetric intersecting precut hydraulic fracturing in mine rock-breaking
Authors: Yu Qian , Zhao Yuemao , Guo Tao , Yang Shuhao , Zhu Hongmo
Published: October 2024

As a mine rock-breaking technique, hydraulic fracturing technology can reduce the amount of explosives used, which enhance safety and reduce environmental pollution in mines. After precutting along the borehole axis, hydraulic fractures will expand along the precutting direction within a certain range and reduce initiation pressure. These hydraulic fractures cut through the rock mass, reducing its integrity and weakening its mechanical properties. Hydraulic fracturing with axially symmetric intersecting precut fractures not only controls the multi-directional propagation of fractures but also increases the fractures within rock mass. The lattice method simulated the hydraulic fracturing process, focusing on the parameters like angles between precut fractures and the minimum horizontal principal stress, the maximum horizontal principal stress, and angles between intersecting precut fractures. Results indicate that the hydraulic fractures propagate along intersecting precut fractures, forming main and interconnected secondary fractures. The directional cutting effect is influenced by the number of secondary fractures. With the increase in the angle between precut fractures and the minimum horizontal principal stress, the maximum horizontal principal stress, the angle between precut fractures, the area of secondary fractures decreased, and the expansion extent of main fractures along the precut fractures increased, indicating better directional effects. The study identifies relationships between initiation time, initiation pressure, and parameters. These findings provide valuable technical guidance for designing on-site construction plans for hydraulic fracturing projects involving intersecting precut fractures.