cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Charmonium and light hadron spectroscopy
Creators: name: Shen, Chengping
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: In this report I review some results on the charmonium and light hadron spectroscopy mainly from BESIII and Belle experiments. For the charmonium, the contents include the observation of $ψ(4040)/ψ(4160) \to η\jpsi$, the measurements of the $η_c/η_c(2S)$ resonance parameters and their decays, the evidence of the $ψ_2(1^3D_2)$ state in the $χ_{c1}γ$ mass spectrum. For the light hadron spectroscopy, the contents include the $X(1835)$ research in $e^+e^- \to \jpsi + X(1835)$ and $γγ\to η' π^+ π^-$ processes, and the analysis of the $ηη$, $ωϕ$, $ϕϕ$ and $ωω$ mass spectra in low mass region.
description: 12 pages, 12 figures. To appear in International Journal of Modern Physics: Conference Series for The XXXIII international symposium on Physics in Collision, Beijing, P. R. China from 03 - 07 September 2013
Moment tensor inversion of perforation shots using distributed acoustic sensing
Creators: name: Bader, Milad
name: Clapp, Robert G.
name: Nihei, Kurt T.
name: Biondi, Biondo
Publisher: name: arXiv
Year: 2023
Subjects: subject: Geophysics (physics.geo-ph)
subject: FOS: Physical sciences

description: Distributed acoustic sensing (DAS) fibers have enabled various geophysical applications in unconventional reservoirs. Combined with perforation shots, a DAS fiber can record valuable guided waves that propagate in the reservoir formation and carry information about its properties. However, the representation of perforation shots as seismic sources, needed to conduct quantitative analysis, remains unknown. We model such sources using a superposition of three mechanisms for which we derive the moment tensor representation. Using field DAS data recorded in the same well where the perforations are located, we establish a workflow to invert the resolvable components of the total moment tensor for 100 different perforation shots. By scrutinizing the inversion results, we conjecture that the moment tensor can indicate how effectively a perforation shot creates micro-cracks in the surrounding rock. Furthermore, our inverted moment tensors form the basis for a subsequent elastic full-waveform inversion.
description: This work has been submitted for publication in Geophysics under the reference GEO-2023-0040
Thermoplastic Induction Welding for Sustainable Aircraft: an Industrial Perspective
Creators: name:  REMY GARCIA
name:   IGOR KIYANITSYN
name:   MILAN MITROVIC
name:   HAJER SAADA
name:   ALFRED TANG
name:   MICHEL VAN TOOREN
name:   LAURA MAININI
Publisher: name: Proceedings of the Aerospace Europe Conference - EUCASS - CEAS - 2023
Year: 2023
Subjects: STRUCTURES AND MATERIALS
SUSTAINABLE AVIATION
MULTIPHYSICS SIMULATION
MULTIDISCIPLINARY DESIGN OPTIMIZATION

description: Thermoplastic components are key elements for more sustainable structures in the aerospace industry due to their light-weight and weldability that improve manufacturing and offers better opportunities for recyclability. In this paper, we discuss the main research challenges associated with induction welding of thermoplastic composites at scale and their impact on sustainable aviation. A framework of methods to address these challenges, formulated as multidisciplinary design optimization problems, is discussed together with ongoing projects and partnerships.
IFU spectroscopy of 10 early type galactic nuclei: II - Nuclear emission line properties
Creators: name: Ricci, T. V.
name: Steiner, J. E.
name: Menezes, R. B.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Although it is well known that massive galaxies have central black holes, most of them accreting at low Eddington ratios, many important questions still remain open. Among them, are the nature of the ionizing source, the characteristics and frequencies of the broad line region and of the dusty torus. We report observations of 10 early-type galactic nuclei, observed with the IFU/GMOS spectrograph on the Gemini South telescope, analysed with standard techniques for spectral treatment and compared with results obtained with principal component analysis Tomography (Paper I). We performed spectral synthesis of each spaxel of the data cubes and subtracted the stellar component from the original cube, leaving a data cube with emission lines only. The emission lines were decomposed in multi-Gaussian components. We show here that, for eight galaxies previously known to have emission lines, the narrow line region can be decomposed in two components with distinct line widths. In addition to this, broad H$α$ emission was detected in six galaxies. The two galaxies not previously known to have emission lines show weak H$α$+[N II] lines. All 10 galaxies may be classified as low-ionization nuclear emission regions in diagnostic diagrams and seven of them have bona fide active galactic nuclei with luminosities between 10$^{40}$ and 10$^{43}$ erg s$^{-1}$. Eddington ratios are always < 10$^{-3}$.
description: 16 pages, 9 figures, accepted for publication in MNRAS
Drastic enhancement of the superconducting temperature in type-II Weyl semimetal candidate MoTe$_2$ via biaxial strain
Creators: name: Yip, King Yau
name: Lam, Siu Tung
name: Yu, Kai Ham
name: Chow, Wing Shing
name: Zeng, Jiayu
name: Lai, Kwing To
name: Goh, Swee K.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Type-II Weyl semimetal candidate MoTe$_2$, which superconducts at T_c~0.1 K, is one of the promising candidates for realizing topological superconductivity. However, the exceedingly low $T_c$ is associated with a small upper critical field ($H_{c2}$), implying a fragile superconducting phase that only exists on a small region of the $H$-$T$ phase diagram. Here, we describe a simple and versatile approach based on the differential thermal expansion between dissimilar materials to subject a thin single crystalline MoTe$_2$ to biaxial strain. With this approach, we successfully enhance the $T_c$ of MoTe$_2$ five-fold and consequently expand the superconducting region on the $H$-$T$ phase diagram significantly. To demonstrate the relative ease of studying the superconductivity in the biaxially strained MoTe$_2$, we further present the magnetotransport data, enabling the study of the temperature-dependent $H_{c2}$ and the anisotropy of the superconducting state which would otherwise be difficult to obtain in a free-standing MoTe$_2$. Our work shows that biaxial strain is an effective knob to tune the electronic properties of MoTe$_2$. Due to the simplicity of our methodology to apply biaxial strain, we anticipate its direct applicability to a wider class of quantum materials.
description: 6 pages, 4 figures. Reference list updated. APL Materials (in press)
Significant experiences outside my country: Reading in a foreign public library.
Creators: name: Siming Zheng
Publisher: name: figshare
Year: 2020
Subjects: subject: Library and Information Studies
subject: FOS: Media and communications

description: Dear,
Significant experiences outside my country: Reading in a foreign public library.

Thank you for your attention.
Best regards,
Applicant: Siming Zheng
Keeping turbofans cool: Aerodynamic upgrade of bypass surface heat exchangers (EU Project SACOC)
Creators: name:  ALBERTO BROATCH
name:   PABLO OLMEDA
name:   JORGE GARCIA-TISCAR
name:   ANDRES FELGUEROSO
Publisher: name: Proceedings of the Aerospace Europe Conference - EUCASS - CEAS - 2023
Year: 2023
Subjects: THERMAL MANAGEMENT
HEAT EXCHANGERS
SACOC
SAOHE
WIND TUNNEL
EXPERIMENTAL AERODYNAMICS

description: New generation turbofan aeroengines are facing a challenge regarding thermal management, and hence, heat exchangers are becoming a key factor in their development. In this context, the EU-funded Clean Sky 2 project SACOC5 addressed the aerodynamic upgrade of finned heat exchangers mounted on the inner wall of the secondary duct (bypass) of a turbofan. Such a design implies a significant trade-off between the heat exchanger\'s thermal performance improvement and the aerodynamic penalties, which are measured by drag or pressure loss. In addition, vibration and noise generation are also of concern, and thus the fluid-structure interaction must be investigated. However, in the case of large turbofan aero engines, full-scale tests are time-consuming and expensive; thus, reduced-scale testing in wind tunnels is much preferable. There are different approaches to designing these reduced-scale wind tunnels, such as a very narrow channel8 or, in the case of heat exchangers situated before the outlet guide vanes, a twisted wind tunnel.10 13 In this work, we present a summary of a new, cost-effective, reduced-scale wind tunnel design that reproduces turbofan bypass conditions.3 Then we focus on aerothermal and vibration results obtained during the experimental campaign of project SACOC, comprising a baseline standard heat exchanger design and two aerodynamically-upgraded heat exchanger geometry proposals.
Higher-order topological superconductivity in monolayer WTe$_2$ from repulsive interactions
Creators: name: Jahin, Ammar
name: Wang, Yuxuan
Publisher: name: arXiv
Year: 2023
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Superconductivity has been experimentally observed in monolayer WTe2, which in-plane field measurements suggested are of spin-triplet nature. Furthermore, it has been proposed that with a $p$-wave pairing, the material is a second-order topological superconductor with a pair of Majorana zero modes at the corners of a finite sample. We show that for a repulsive on-site interaction and sizable Fermi surfaces, the desired p-wave state arises naturally due to the Kohn-Luttinger mechanism, and indeed a finite superconducting sample hosts corner Majorana zero modes. We study the behavior of the critical temperature in response to external in-plane magnetic fields. We find an enhancement to the critical temperature that depends on the direction of the magnetic field, which can be directly verified experimentally.
AMD-HookNet for Glacier Front Segmentation
Creators: name: Wu, Fei
name: Gourmelon, Nora
name: Seehaus, Thorsten
name: Zhang, Jianlin
name: Braun, Matthias
name: Maier, Andreas
name: Christlein, Vincent
Publisher: name: arXiv
Year: 2023
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: Knowledge on changes in glacier calving front positions is important for assessing the status of glaciers. Remote sensing imagery provides the ideal database for monitoring calving front positions, however, it is not feasible to perform this task manually for all calving glaciers globally due to time-constraints. Deep learning-based methods have shown great potential for glacier calving front delineation from optical and radar satellite imagery. The calving front is represented as a single thin line between the ocean and the glacier, which makes the task vulnerable to inaccurate predictions. The limited availability of annotated glacier imagery leads to a lack of data diversity (not all possible combinations of different weather conditions, terminus shapes, sensors, etc. are present in the data), which exacerbates the difficulty of accurate segmentation. In this paper, we propose Attention-Multi-hooking-Deep-supervision HookNet (AMD-HookNet), a novel glacier calving front segmentation framework for synthetic aperture radar (SAR) images. The proposed method aims to enhance the feature representation capability through multiple information interactions between low-resolution and high-resolution inputs based on a two-branch U-Net. The attention mechanism, integrated into the two branch U-Net, aims to interact between the corresponding coarse and fine-grained feature maps. This allows the network to automatically adjust feature relationships, resulting in accurate pixel-classification predictions. Extensive experiments and comparisons on the challenging glacier segmentation benchmark dataset CaFFe show that our AMD-HookNet achieves a mean distance error of 438 m to the ground truth outperforming the current state of the art by 42%, which validates its effectiveness.
Localization-delocalization transitions in turbophoresis of inertial particles
Creators: name: Belan, S.
name: Fouxon, I.
name: Falkovich, G.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Chaotic Dynamics (nlin.CD)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: Small aerosols drift down temperature or turbulence gradient since faster particles fly longer distances before equilibration. That fundamental phenomenon, called thermophoresis or turbophoresis, is widely encountered in nature and used in industry. It is universally believed that particles moving down the kinetic energy gradient must concentrate in minima (say, on walls in turbulence). Here we show that this is incorrect: escaping minima is possible for inertial particles whose time of equilibration is longer than the time to reach the minimum. The best way out is always through: particles escape by flying through minima or reflecting from walls. We solve the problem analytically and find the phase transition as a sign change of the mean velocity. That means separation: light particles concentrate in a minimum while heavy particles spread away from it (gravity can reverse the effect). That discovery changes understanding of that fundamental phenomenon and may find numerous applications.
description: 5 pages
Using Learned Indexes to Improve Time Series Indexing Performance on Embedded Sensor Devices
Creators: name: Ding, David
name: Carvalho, Ivan
name: Lawrence, Ramon
Publisher: name: arXiv
Year: 2023
Subjects: subject: Databases (cs.DB)
subject: Signal Processing (eess.SP)
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: Efficiently querying data on embedded sensor and IoT devices is challenging given the very limited memory and CPU resources. With the increasing volumes of collected data, it is critical to process, filter, and manipulate data on the edge devices where it is collected to improve efficiency and reduce network transmissions. Existing embedded index structures do not adapt to the data distribution and characteristics. This paper demonstrates how applying learned indexes that develop space efficient summaries of the data can dramatically improve the query performance and predictability. Learned indexes based on linear approximations can reduce the query I/O by 50 to 90% and improve query throughput by a factor of 2 to 5, while only requiring a few kilobytes of RAM. Experimental results on a variety of time series data sets demonstrate the advantages of learned indexes that considerably improve over the state-of-the-art index algorithms.
description: To appear in SENSORNETS 2023
Electronic Correlation Effects on Stabilizing a Perfect Kagome Lattice and Ferromagnetic Fluctuation in LaRu$_3$Si$_2$
Creators: name: Wang, Yilin
Publisher: name: arXiv
Year: 2023
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: A perfect Kagome lattice features flat bands that usually lead to strong electronic correlation effects, but how electronic correlation, in turn, stabilizes a perfect Kagome lattice has rarely been explored. Here, we study such effect in a superconducting ($T_c \sim 7.8$ K) Kagome metal LaRu$_3$Si$_2$ with a distorted Kagome plane consisting of pure Ru ions, using density functional theory plus $U$ and plus dynamical mean-field theory. We find that increasing electronic correlation can stabilize a perfect Kagome lattice and induce substantial ferromagnetic fluctuations in LaRu$_3$Si$_2$. By comparing the calculated magnetic susceptibilities to experimental data, LaRu$_3$Si$_2$ is found to be on the verge of becoming a perfect Kagome lattice. It thus shows moderate but non-negligible electronic correlations and ferromagnetic fluctuations, which are crucial to understanding the experimentally observed non-Fermi-liquid behavior and the pretty high superconducting $T_c$ of LaRu$_3$Si$_2$.
description: 4 pages and 4 figures in main text. Appear soon in JUSTC
Free-flight testing of proximal spheres and cubes in Mach 14 hypersonic flow
Creators: name:  DANIEL G. KOVACS
name:   GUILLAUME GROSSIR
name:   GRIGORIOS DIMITRIADIS
name:   OLIVIER CHAZOT
Publisher: name: Proceedings of the Aerospace Europe Conference - EUCASS - CEAS - 2023
Year: 2023
Subjects: HYPERSONIC
AERODYNAMICS
FREE-FLIGHT TESTING
PROXIMAL BODIES
FRAGMENT SEPARATION
LONGSHOT

description: Free-flight testing in hypersonic wind tunnels has shown good capabilities for analyzing the flight of debris objects and scenarios for their separation. The free-flight methodology implemented in the VKI Longshot facility was recently updated to facilitate the aerodynamic analysis of trajectories with six degrees of freedom. The image processing algorithms are extended in the present work to carry out separation studies where the models can present overlapping configurations. A dual-camera setup and the new routines proved suitable for tracking the motion of two spheres and cubes undergoing interactions. The experimental results confirm that when non-spherical geometries interfere, the separation behavior is case-dependent and sensitive to the objects\' orientation.
Decentralized Inexact Proximal Gradient Method With Network-Independent Stepsizes for Convex Composite Optimization
Creators: name: Guo, Luyao
name: Shi, Xinli
name: Cao, Jinde
name: Wang, Zihao
Publisher: name: arXiv
Year: 2023
Subjects: subject: Optimization and Control (math.OC)
subject: Machine Learning (cs.LG)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences

description: This paper proposes a novel CTA (Combine-Then-Adapt)-based decentralized algorithm for solving convex composite optimization problems over undirected and connected networks. The local loss function in these problems contains both smooth and nonsmooth terms. The proposed algorithm uses uncoordinated network-independent constant stepsizes and only needs to approximately solve a sequence of proximal mappings, which is advantageous for solving decentralized composite optimization problems where the proximal mappings of the nonsmooth loss functions may not have analytical solutions. For the general convex case, we prove an O(1/k) convergence rate of the proposed algorithm, which can be improved to o(1/k) if the proximal mappings are solved exactly. Furthermore, with metric subregularity, we establish a linear convergence rate for the proposed algorithm. Numerical experiments demonstrate the efficiency of the algorithm.
Universal mask for hard X rays
Creators: name: Ceddia, David
name: Aminzadeh, Alaleh
name: Cook, Philip K.
name: Pelliccia, Daniele
name: Kingston, Andrew M.
name: Paganin, David M.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Image and Video Processing (eess.IV)
subject: Accelerator Physics (physics.acc-ph)
subject: Optics (physics.optics)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Physical sciences

description: The penetrating power of X rays underpins important applications such as medical radiography. However, this same attribute makes it challenging to achieve flexible on-demand patterning of X-ray beams. One possible path to this goal is ``ghost projection'', a method which may be viewed as a reversed form of classical ghost imaging. This technique employs multiple exposures, of a single illuminated non-configurable mask that is transversely displaced to a number of specified positions, to create any desired pattern. An experimental proof-of-concept is given for this idea, using hard X rays. The written pattern is arbitrary, up to a tunable constant offset, and its spatial resolution is limited by both (i) the finest features present in the illuminated mask and (ii) inaccuracies in mask positioning and mask exposure time. In principle, the method could be used to make a universal lithographic mask in the hard-X-ray regime. Ghost projection might also be used as a dynamically-configurable beam-shaping element, namely the hard-X-ray equivalent of a spatial light modulator. The underpinning principle can be applied to gamma rays, neutrons, electrons, muons, and atomic beams. Our flexible approach to beam shaping gives a potentially useful means to manipulate such fields.
description: Revised for resubmission to Optica; numerous clarifications throughout the paper; Sec. 4 (numbered item 2) and Supplement 1 Sec. 2 significantly extended; all figures and ancillary movies unchanged
Optical quasi-periodic oscillation and color behavior of blazar PKS 2155-304
Creators: name: Zhang, Bing-Kai
name: Zhao, Xiao-Yun
name: Wang, Chun-Xiao
name: Dai, Ben-Zhong
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: PKS 2155-304 is a well studied BL Lac object in the southern sky. The historical optical data during different period have been collected and compiled. Light curves with a time span of 35 years have been constructed. The R-band light curve has been analyzed by means of three methods: epoch folding method, Jurkevich method and discrete correlation function (DCF) method. It is derived that there is an evident periodic component of 317 days (i.e. 0.87 yr) superposed on a long-term trend with large-amplitude variation in the light curve. The variability of this source is accompanied by a slight color variation, and the brightness and color index are correlated with each other. On the long time-scale, PKS 2155-304 exhibits a tendency of bluer-when-brighter, which means the spectrum becomes flatter when the source brightens.
description: 9 pages, 4 figures. Accepted for publication in RAA (Research in Astronomy and Astrophysics)
A New Efficient Method for Calculation of Frenkel Exciton Parameters in Molecular Aggregates
Creators: name: Plötz, Per-Arno
name: Niehaus, Thomas
name: Kühn, Oliver
Publisher: name: arXiv
Year: 2013
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: Biological Physics (physics.bio-ph)
subject: FOS: Physical sciences

description: The Frenkel exciton Hamiltonian is at the heart of many simulations of excitation energy transfer in molecular aggregates. It separates the aggregate into Coulomb-coupled monomers. Here it is shown that the respective parameters, i.e. monomeric excitation energies and Coulomb couplings between transition densities, can be efficiently calculated using time-dependent tight-binding-based density functional theory (TD-DFTB). Specifically, Coulomb couplings are expressed in terms of self-consistently determined Mulliken transition charges. The determination of the sign of the coupling requires an additional super-molecule calculation. The approach is applied to two dimer systems. First, formaldehyde oxime for which a detailed comparison with standard DFT using the B3LYP and the PBE functionals is provided. Second, the Coulomb coupling is explored in dependence on the intermolecular coordinates for a perylene bisimide dimer. This provides structural evidence for the previously observed biphasic aggregation behavior of this dye.
Three Fibonacci-Chain Aperiodic Algebras
Creators: name: Corradetti, Daniele
name: Chester, David
name: Aschheim, Raymond
name: Irwin, Klee
Publisher: name: arXiv
Year: 2023
Subjects: subject: Rings and Algebras (math.RA)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: Aperiodic algebras are infinite dimensional algebras with generators corresponding to an element of the aperiodic set. These algebras proved to be an useful tool in studying elementary excitations that can propagate in multilayered structures and in the construction of some integrable models in quantum mechanics. Starting from the works of Patera and Twarock we present three aperiodic algebras based on Fibonacci-chain quasicrystals: a quasicrystal Lie algebra, an aperiodic Witt algebra and, finally, an aperiodic Jordan algebra. While a quasicrystal Lie algebra was already constructed from a modification of the Fibonacci chain, we here present an aperiodic algebra that matches exactly the original quasicrystal. Moreover, this is the first time to our knowledge, that an aperiodic Jordan algebra is presented leaving room for both theoretical and applicative developments.
description: 13 pages 1 figure
Affine Nijenhuis Operators and Hochschild Cohomology of Trusses
Creators: name: Brzeziński, Tomasz
name: Papworth, James
Publisher: name: arXiv
Year: 2023
Subjects: subject: Rings and Algebras (math.RA)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 20N10, 16E40, 81R12

description: The classical Hochschild cohomology theory of rings is extended to abelian heaps with distributing multiplication or trusses. This cohomology is then employed to give necessary and sufficient conditions for a Nijenhuis product on a truss (defined by the extension of the Nijenhuis product on an associative ring introduced by Cariñena, Grabowski and Marmo in [Internat. J. Modern Phys. A 15 (2000), 4797-4810, arXiv:math-ph/0610011]) to be associative. The definition of Nijenhuis product and operators on trusses is then linearised to the case of affine spaces with compatible associative multiplications or associative affgebras. It is shown that this construction leads to compatible Lie brackets on an affine space.
Performance estimation of supersonic impulse turbine at transient conditions
Creators: name:  ROBSON H. S. HAHN
name:   TOBIAS TRAUDT
name:   ANIRUDH M. SARAF
name:   JAN DEEKEN
name:   MICHAEL OSCHWALD
name:   STEFAN SCHLECHTRIEM
Publisher: name: Proceedings of the Aerospace Europe Conference - EUCASS - CEAS - 2023
Year: 2023
Subjects: TURBINE
SUPERSONIC
TRANSIENT
TURBOPUMP
LUMEN

description: During startup as well as operational point changes, a supersonic impulse turbine can encounter gas dynamical conditions in which can result in excessive loads or immediate loss of performance. Effects such flutter [ l], buzzing [ 2], under and over expanded flow and full gas blockage [ 3] can appear and induce high levels of stress, reducing the expected life of the turbine or deteriorating the expected efficiency. Most performance prediction method for supersonic impulse turbine are restrictive for one single operational conditions and doesn\'t take into consideration the majority of effects in the system, as partial admission, leakage losses, etc. However, in a throttleable engine, the optimization must cover all operational envelope, as well as the transient conditions in between, as well as the startup, resulting in increase of performance in all expected conditions. Different considerations need to be taken into account while evaluating the transient effects during performance estimation at such low load points. The most significant constrain is the evaluation of the das-dynamic condition and the boundary-layer effect during the analysis process in the pre-defined operation range. The main models for design turbine systems applied for LRE are adjusted to engines with medium to high thrust levels (usually above 50-lO0kN), where various losses, as friction, leakage, non-uniform flow, partial admission and others are considerably smaller than the performance generated per rotor blade. With a decrease of nominal thrust at design conditions, especially during starting conditions or transient points, the turbomachinery size decreases considerably, result in losses outside of the wellknovm modelled ranges, making the performance estimation of such components imprecise. The improvement of in house tools for off-design conditions prediction and its validations with experimental test cases allow to better estimate the effects of startup conditions and transient effects as well as its expected performance, increasing reliability on current tests and futures designs, with adequate precision for turbomachinery ranging from small sizes to standard high thrust models. Copyright 2023 by Robson H. S. Hahn. Posted online by the EUCASS association with permission.
Molecular structures and clustering effects in reactions induced by light nuclei
Creators: name: Beck, C.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: $α$-clustering study since the pioneering discovery of $^{12}$C+$^{12}$C molecular resonances half a century ago. Our knowledge on physics of nuclear molecules has increased considerably and nuclear clustering remains one of the most fruitful domains of nuclear physics, facing some of the greatest challenges and opportunities in the years ahead. The occurrence of "exotic" shapes in light $N$=$Z$ $α$-like nuclei is investigated. Various approaches of the superdeformed and hyperdeformed bands associated with quasimolecular resonant structures are presented. Evolution of clustering from stability to the drip-lines is examined: clustering aspects are, in particular, discussed for light exotic nuclei with large neutron excess such as neutron-rich Oxygen isotopes with their complete spectrocopy.
description: 16 pages, 7 figures, Invited Talk presented at the First International African Symposium on Exotic Nuclei IASEN2013 Ithemba LABS Cape Town, South Africa, December 2-6, 2013; Proceedings to be published by World Scientific
Size effect on the thermal conductivity of a type-I clathrate
Creators: name: Lužnik, Monika
name: Lientschnig, Günther
name: Taupin, Mathieu
name: Steiger-Thirsfeld, Andreas
name: Prokofiev, Andrey
name: Paschen, Silke
Publisher: name: arXiv
Year: 2023
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Clathrates are a materials class with an extremely low phonon thermal conductivity, which is a key ingredient for a high thermoelectric conversion efficiency. Here, we present a study on the type-I clathrate La$_{1.2}$Ba$_{6.8}$Au$_{5.8}$Si$_{38.8}\square_{1.4}$ directed at lowering the phonon thermal conductivity even further by forming mesoscopic wires out of it. Our hypothesis is that the interaction of the low-energy rattling modes of the guest atoms (La and Ba) with the acoustic modes, which originate mainly from the type-I clathrate framework (formed by Au and Si atoms, with some vacancies $\square$), cuts off their dispersion and thereby tilts the balance of phonons relevant for thermal transport to long-wavelength ones. Thus, size effects are expected to set in at relatively long length scales. The structuring was carried out using a top-down approach, where the wires, ranging from 1260 nm to 630 nm in diameter, were cut from a piece of single crystal using a focused ion beam technique. Measurements of the thermal conductivity were performed with a self-heating $3ω$ technique down to 80 K. Indeed, they reveal a reduction of the room-temperature phonon thermal conductivity by a sizable fraction of $\sim$40 % for our thinnest wire, thereby confirming our hypothesis.
Progress Summary of H2020-project FALCon
Creators: name:  MARTIN SIPPEL
name:   SINGH
name:   STAPPERT
Publisher: name: Proceedings of the Aerospace Europe Conference - EUCASS - CEAS - 2023
Year: 2023
Subjects: RLV
IN-AIR-CAPTURING
FALCON

description: AERO SP ACE EUROPE CONFERENCE 2023 -1 QTH EU CASS -9TH CEAS DOI: Progress Summary of H2020-project FALCon Martin Sippel1 *, Sunayna Singh1 , Sven Stappert1 * Corresponding author 1 DIR Space Launcher System Analysis SART, 28359 Bremen, Germany, Martin.Sippel@dlr.de The innovative approach \"in-air-capturing\" for the efficient return of reusable space transportation vehicles has been refined in the EC-funded H2020-project FALCon. Following the basic idea, winged stages are to be caught in the air and towed by subsonic airplanes back to their launch site without any necessity of an own propulsion system. The project FALCon (Formation flight for in-Air Launcher 1\'1 stage Capturing demonstration) funded by EC in Horizon 2020 and running from 2019 until 2022 has achieved significant progress. The project finished after 45 months in November 2022. The paper provides a retrospective progress summary. The successful establishment of significantly refined simulation models and the definition of the development roadmap for the next steps in technology maturation are presented. Further, lessons learned from the complex authorization process of the UA Vs to be used in the lab-scale flight demonstrations are discussed. Finally, an outlook on the intended follow-up activities is given, including an estimate of the relatively modest investments required. Abbreviations ACCD AoA BVLOS CFD CoG DRL GLOW IAC IR LID Aerodynamically Controlled Device Angle of Attack Beyond Visual Line of Sight Computational Fluid Dynamics Center of Gravity Down Range Landing Gross Lift-Off Mass In-Air-Capturing Infrared Lift to Drag ratio Capturing LFBB MAR l\\AECO RCS RLV RTLS TRL TSTO TVC UAV Liquid Fly-Back Booster Mid-Air Retrieval Main Engine Cut-Off Reaction Control System Reusable Launch Vehicle Return To Launch Site Technology Readiness Level Two-Stage-Io-Orbit Thrust Vector Control Unmanned Aerial Vehicle
Bubble nucleation and jetting inside a millimetric droplet
Creators: name: Rosselló, Juan Manuel
name: Reese, Hendrik
name: Raman, K. Ashoke
name: Ohl, Claus-Dieter
Publisher: name: arXiv
Year: 2023
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: In this work, we present experiments and simulations on the nucleation and successive dynamics of laser-induced bubbles inside liquid droplets in free-fall motion, i.e. a case with a free boundary in all directions. The droplets of a millimetric size have a nearly spherical shape by the moment the bubble is nucleated. We have investigated the nucleation of secondary bubbles induced by the rarefaction wave that is produced when the shock wave emitted by the laser-induced plasma reflects at the drop surface. Interestingly, three-dimensional clusters of cavitation bubbles are observed. Their shape is compared with the negative pressure distribution computed with a CFD model and allows us to estimate a cavitation threshold value. High-speed recordings of the drop/bubble dynamics are complemented by the velocity and pressure fields simulated for the same initial conditions. The effect of the proximity of a curved free surface on the jetting dynamics of the bubbles was qualitatively assessed by classifying the cavitation events using a non-dimensional stand-off parameter which depends on the drop size, the bubble maximum radius and the relative position of the bubble inside the drop. Additionally, we studied the role of the drop's curvature by implementing a structural similarity algorithm to compare cases with bubbles produced near a flat surface to the bubbles inside the drop. This quantitative comparison method indicated the existence of equivalent stand-off distances at which bubbles influenced by different boundaries behave in a very similar way. The oscillation of the laser-induced bubbles promote the onset of Rayleigh-Taylor and Rayleigh-Plateau instabilities, observed on the drop's surface. This phenomenon was studied by varying the ratio of the maximum radii of the bubble and the drop. The specific mechanisms leading to the destabilisation of the droplet surface were identified.
Gravitational waves from the merger of two primordial black hole clusters
Creators: name: Eroshenko, Yury
name: Stasenko, Viktor
Publisher: name: arXiv
Year: 2023
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: The orbital evolution of a binary system consisting of two primordial black hole clusters is investigated. Such clusters are predicted in some theoretical models with broken symmetry in the inflation Lagrangian. A cluster consists of the most massive central black hole surrounded by many smaller black holes. Similar to single primordial black holes, clusters can form gravitationally bounded pairs and merge during their orbital evolution. The replacement of single black holes by such clusters significantly changes the entire merger process and the final rate of gravitational wave bursts in some parameter ranges (with sufficiently large cluster radii). A new important factor is the tidal gravitational interaction of the clusters. It leads to an additional dissipation of the orbital energy, which is transferred into the internal energy of the clusters or carried away by black holes flying out of the clusters. Comparison with the data of gravitational-wave telescopes allows one to constrain the fractions of primordial black holes in clusters, depending on their mass and compactness. Even the primordial black hole fraction in the composition of dark matter $\simeq1$ turns out to be compatible with LIGO/Virgo observational data, if the black holes are in clusters.
description: 7 pages, 4 figures
Energy-Efficient Power Adaptation for Cognitive Radio Systems under Imperfect Channel Sensing
Creators: name: Ozcan, Gozde
name: Gursoy, M. Cenk
Publisher: name: arXiv
Year: 2014
Subjects: subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: In this paper, energy efficient power adaptation is considered in sensing-based spectrum sharing cognitive radio systems in which secondary users first perform channel sensing and then initiate data transmission with two power levels based on the sensing decisions (e.g., idle or busy). It is assumed that spectrum sensing is performed by the cognitive secondary users, albeit with possible errors. In this setting, the optimization problem of maximizing the energy efficiency (EE) subject to peak/average transmission power constraints and average interference constraints is considered. The circuit power is taken into account for total power consumption. By exploiting the quasiconcave property of the EE maximization problem, the original problem is transformed into an equivalent parameterized concave problem and Dinkelbach's method-based iterative power adaptation algorithm is proposed. The impact of sensing performance, peak/average transmit power constraints and average interference constraint on the energy efficiency of cognitive radio systems is analyzed.
description: To Appear at 2014 IEEE INFOCOM Workshop on Green Cognitive Communications and Computing Networks. Some typos are fixed
Cross-center Early Sepsis Recognition by Medical Knowledge Guided Collaborative Learning for Data-scarce Hospitals
Creators: name: Ding, Ruiqing
name: Rong, Fangjie
name: Han, Xiao
name: Wang, Leye
Publisher: name: arXiv
Year: 2023
Subjects: subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: There are significant regional inequities in health resources around the world. It has become one of the most focused topics to improve health services for data-scarce hospitals and promote health equity through knowledge sharing among medical institutions. Because electronic medical records (EMRs) contain sensitive personal information, privacy protection is unavoidable and essential for multi-hospital collaboration. In this paper, for a common disease in ICU patients, sepsis, we propose a novel cross-center collaborative learning framework guided by medical knowledge, SofaNet, to achieve early recognition of this disease. The Sepsis-3 guideline, published in 2016, defines that sepsis can be diagnosed by satisfying both suspicion of infection and Sequential Organ Failure Assessment (SOFA) greater than or equal to 2. Based on this knowledge, SofaNet adopts a multi-channel GRU structure to predict SOFA values of different systems, which can be seen as an auxiliary task to generate better health status representations for sepsis recognition. Moreover, we only achieve feature distribution alignment in the hidden space during cross-center collaborative learning, which ensures secure and compliant knowledge transfer without raw data exchange. Extensive experiments on two open clinical datasets, MIMIC-III and Challenge, demonstrate that SofaNet can benefit early sepsis recognition when hospitals only have limited EMRs.
description: 7 pages, 2 figures
LipLearner: Customizable Silent Speech Interactions on Mobile Devices
Creators: name: Su, Zixiong
name: Fang, Shitao
name: Rekimoto, Jun
Publisher: name: arXiv
Year: 2023
Subjects: subject: Human-Computer Interaction (cs.HC)
subject: Artificial Intelligence (cs.AI)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Silent speech interface is a promising technology that enables private communications in natural language. However, previous approaches only support a small and inflexible vocabulary, which leads to limited expressiveness. We leverage contrastive learning to learn efficient lipreading representations, enabling few-shot command customization with minimal user effort. Our model exhibits high robustness to different lighting, posture, and gesture conditions on an in-the-wild dataset. For 25-command classification, an F1-score of 0.8947 is achievable only using one shot, and its performance can be further boosted by adaptively learning from more data. This generalizability allowed us to develop a mobile silent speech interface empowered with on-device fine-tuning and visual keyword spotting. A user study demonstrated that with LipLearner, users could define their own commands with high reliability guaranteed by an online incremental learning scheme. Subjective feedback indicated that our system provides essential functionalities for customizable silent speech interactions with high usability and learnability.
description: Conditionally accepted to the ACM CHI Conference on Human Factors in Computing Systems 2023 (CHI '23)
A prospective market business perspective on Lunar ISRU for propellant applications
Creators: name:  AINARDI
name:   STORCK
name:   ESTEJEL
name:   BARATTE
Publisher: name: Proceedings of the Aerospace Europe Conference - EUCASS - CEAS - 2023
Year: 2023
Subjects: SUSTAINABILITY
VALUE CHAIN
ECOSYSTEM
PROSPECTIVE

description: Lunar resources are increasingly being considered as a key element of future exploration missions. By reducing the need for incoming material fluxes, In-situ resources utilization (ISRU) might act as an enabler to long-term, sustainable human presence on the Moon, and facilitate the use of the Moon as a starting point for further exploration of the Solar system. While it is crucial, the economic sustainability of lunar ISRU currently remains a subject of research [1,2]. Our study identifies the resources available up to date on the Moon, that can be categorized into two main types: material resources, and immaterial resources. In terms of demand, the activities on the Moon that could create needs for propellant can actually be classified into 5 main \"end-goals\" : scientific exploration, resource utilization, manufacturing, construction and tourism. The future of these activities will strongly depend on three macro-drivers: availability of lunar energy, human presence on the Moon, and quantity of available resources. From these macro-drivers, we envision five potential archetype scenarios for the future. To estimate the market size of 02 propellant for each, we identify 16 potential vehicles and then focus on those using cryogenic chemical propellants: unmanned and manned launchers, manned spacecraft, space cargo, point-to-point rockets, and landers. These assumptions allow to derive a preliminary estimate of 02 propellant demand between almost zero to almost 40 kt/year, mostly driven by trips to Earth.
Numerical framework for aerodynamic and aeroacoustics of bio-inspired UAV blades
Creators: name:  WILKINS ROBBIE
name:   BOUFERROUK ABDESSALEM
Publisher: name: Proceedings of the Aerospace Europe Conference - EUCASS - CEAS - 2023
Year: 2023
Subjects: DRONE
BIO-INSPIRED
CFD
MULTI-ROTOR
UAV

description: With the aim to understand and control the noise from UA Vs, this work presents a numerical framework for a small-scale rotor blade with a bio-inspired finlet design. The simulation framework employs Direct Eddy Simulation (DES) for fluid flow and Ffowcs-Williams-Hawkings (FW-H) acoustic analogy for far-field acoustic data. Aerodynamic and aero-acoustic validation of the framework for a hovering case is achieved using a single DJI-9450 rotor blade. Good agreement is shown against experimental and numerical published data. To allow for ease of modelling of finlets on the blade, the original blade twist was modified from mid to tip, creating an\' idealised\' blade. The time-averaged thrust coefficient of the baseline idealised blade is found to be almost the same as that obtained with finlets, indicating a negligible effect on the blade aerodynamics due to finlets. Although no reliable acoustic data could be obtained with finlet design due to computational limitations, close observation of the flow behaviour reveals some interesting patterns. There is a reduced turbulent kinetic energy (IKE) due to finlets, as well as the occurrence of some discrete turbulent blobs that seem to travel above the finlets. These phenomena could indicate either turbulence lifting of smaller-scale eddies or turbulence channelling by the finlets, both of which are known to reduce noise. The presented framework with initial finlet design and numerical testing can be used for the purpose of future noise-optimisation studies.
Overlapping Inflow Events as Catalysts for Supermassive Black Hole Growth
Creators: name: Carmona-Loaiza, Juan Manuel
name: Colpi, Monica
name: Dotti, Massimo
name: Valdarnini, Riccardo
Publisher: name: arXiv
Year: 2013
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: One of the greatest issues in modelling black hole fuelling is our lack of understanding of the processes by which gas loses angular momentum and falls from galactic scales down to the nuclear region where an accretion disc forms, subsequently guiding the inflow of gas down to the black hole horizon. It is feared that gas at larger scales might still retain enough angular momentum and settle into a larger scale disc with very low or no inflow to form or replenish the inner accretion disc (on ~0.01 pc scales). In this paper we report on hydrodynamical simulations of rotating infalling gas shells impacting at different angles onto a pre-existing, primitive large scale (~10 pc) disc around a super-massive black hole. The aim is to explore how the interaction between the shell and the disc redistributes the angular momentum on scales close to the black hole's sphere of influence. Angular momentum redistribution via hydrodynamical shocks leads to inflows of gas across the inner boundary, enhancing the inflow rate by more than 2-3 orders of magnitude. In all cases, the gas inflow rate across the inner parsec is higher than in the absence of the interaction, and the orientation of the angular momentum of the flow in the region changes with time due to gas mixing. Warped discs or nested misaligned rings form depending on the angular momentum content of the infalling shell relative to the disc. In the cases in which the shell falls in near counter-rotation, part of the resulting flows settle into an inner dense disc which becomes more susceptible to mass transfer.
description: 17 pages, 20 figures. Published in MNRAS, reference added. Monthly Notices of the Royal Astronomical Society, 2013