bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of a novel TORT cable wound of stabilized striated REBCO tapes for reduced magnetization AC losses
Authors: Cuninková Eva , Frolek Lubomír , Šouc Ján , Ferenčík Filip , Bónová Lucia , Száraz Zoltán , Skarba Michal , Hulačová Simona , Pekarčíková Marcela , Šimon Štefan 
Published: May 2024

Abstract
REBCO (rare-earth barium copper oxide) high-temperature superconducting tapes, have a high potential for winding of large magnet coils. Tapes on round tube (TORT) cables represent a promising option for achieving a conductor suitable for the winding of magnet coils. However, certain applications, such as accelerator magnets, require the use of superconducting cables with low magnetization alternative current (AC) losses. There are several methods to reduce AC losses in TORT cables. Our first approach was to get rid of eddy currents by replacing the copper former with dielectric materials based on polymers and composites, i.e. polyethylene terephthalate glycol-modified reinforced with carbon fibers. Additional reduction of hysteretic loss was achieved by striating of copper coated REBCO tapes. We employed chemo-mechanical striating, for these objectives. However, the superconductor is exposed during the striating process, which may lead to later moisture-related degradation. Hence multilayers based on Ti/AlN were deposited using magnetron sputtering in order to protect the superconductor immediately after the striating process from water and atmospheric moisture corrosion. Subsequently, striated tapes as well as the non-striated tapes were then wound onto formers with diameters of 10 mm, 7 mm and 5.5 mm, and then on the short TORT cables bending tests were performed. After each technological step, direct current measurements were performed on the samples and finally the AC losses were measured.
Coulomb impurities in graphene driven by ultrashort electromagnetic pulses: excitation, ionization, and pair creation
Authors: Rakhmanov Saparboy , Egger Reinhold , Matrasulov Davron 
Published: May 2024

Abstract
We provide a theory for electronic transitions induced by ultrashort electromagnetic pulses in two-dimensional artificial relativistic atoms which are created by a charged impurity in a gapped graphene monolayer. Using a non-perturbative sudden-perturbation approximation, we derive and discuss analytical expressions for the probabilities for excitation, ionization and electron-hole pair creation in this system.
Theoretical designing of 9,9'-dicarbazole-based dye via end-group modification for indoor DSSC applications
Authors: Abbas Shahid , Hussain Riaz , Haider Muhammad Durair Sajjad , Jawad Komal , Kanwal Noureen , Hussain Ajaz , Hussain Riaz , Ayub Khurshid , A Assiri Mohammed 
Published: May 2024

Abstract
Molecular modeling has garnered significant attention in the realm of organic solar cells (OSCs) because it holds the promise of producing more efficient OSCs with notably enhanced power conversion efficiency (PCE). In this quest, we have undertaken a strategic modification of the acceptor moieties within the recently synthesized metal-free dicarbazole-based organic dye Cz-2, resulting in five novel theoretical dyes, designated as PT1-PT5. Numerous simulations encompassed both the newly designed compounds and the reference (Cz-2) by using DFT and TD-DFT, a comprehensive characterization aimed at enhancing photovoltaic and optoelectronic properties. We probed into the analysis of ground state geometry, frontier molecular orbitals, transition density matrix, optical properties, density of state, binding energy, molecular electrostatic potential, reorganizational energy, open-circuit voltage, and fill factor. Our findings unveiled a common trend among all the theoretical dyes, a reduction in band gap (Eg), a notable red-shift in absorbance ranging from 434 nm to 554 nm, and lowered binding and excitation energy. The decreased reorganization energy i.e., λ
e and λ
h, spanning a range from 0.0040 to 0.0052 eV and 0.0043 to 0.0075 eV respectively, promised significantly enhanced charge mobility. Intriguingly, the binding energies of all the designed compounds consistently registered values lower than that of reference (R), with figures ranging from 0.55 to 0.64 eV, compared to the binding energy of R (0.67 eV). These dyes show significant potential for indoor photovoltaics as they can absorb light in the visible range for indoor renewable energy applications. Our comprehensive analyses suggest that PT1-PT5 are promising candidates with great potential for advancing the field of renewable energy.
Quantum Boltzmann machines: Clifford algebras and asymptotic analysis
Authors: Trindade Marco A S , Lula-Rocha Vinícius N A 
Published: May 2024

Abstract
We analyze mathematical aspects related to general quantum Boltzmann machine models through representations of algebras and functional analytic techniques. In this context, based on algebraic formulation we show the existence of a symmetry group for a class of Hamiltonians based on generators of Clifford algebras and discuss its implications for the learning scheme. Also, we have developed a rigorous mathematical analysis that allows us to investigate issues related to the asymptotic behavior of quantum Boltzmann machines. Particularly, we obtain a lower bound of fidelity in terms of the upper limit of quantum relative entropy.
Integrated photodetectors embedded within fiber laser based on hybrid rGO:ZnO nanostructures
Authors: Naderi Nima , Ahmad Harith , Ismail Mohammad Faizal 
Published: May 2024

Abstract
Online power monitoring is helpful in fiber-optic communication applications. This report introduced an innovative all-fiber photodetector based on the polished side of an arc-shaped fiber for the optical signals’ in situ measurements. For this purpose, a metal-semiconductor–metal photodetector was designed with multiple interdigitated metal fingers of gold electrodes. A waveguide structure containing polymethyl methacrylate (PMMA), graphene layers, and zinc oxide nanostructures was developed and covered over the arc-shaped fiber. Due to the PMMA’s refractive index (n = 1.4905), the evanescent field of propagating mode was drawn out of the core, thus increasing the light interaction with semiconductor nanostructures. To study the influence of graphene flakes on the optoelectrical behavior of zinc oxide nanostructures, a suspension of graphene oxide (GO) and ZnO nanorods was synthesized and transferred onto the PMMA thin film, which was deposited on the polished side of the arc-shaped fiber. The morphological analysis indicates the formation of ZnO nanorods with different orientations, and these nanorods have the potential to enhance incident photon trapping greatly. Upon photon exposure, the guiding photons in the fiber evanescently coupled with the deposited nanostructures, and the photoexcited electron–hole pairs were generated in the semiconductor material. Using applied voltage across the interdigitated electrodes, the generated excitons were separated and increased the photocurrent, which was monitored precisely by source-measure equipment. The optoelectrical properties of fabricated devices showed that incorporating graphene layers can improve the photon detection performance of the fabricated all-fiber photodetectors based on ZnO nanostructures.
Spatially-curved spacetimes in higher–dimensional Klein–Gordon–Rastall theory
Authors: Rahman Aulia A , Fadhilla Emir S , Gunara Bobby E , Atmaja Ardian N 
Published: May 2024

Abstract
In this paper, we analyze higher-dimensional gravitational Rastall theory coupled with a scalar field on spatially-curved spacetimes. Particularly, the theory admits baryotropic cosmic fluid and a massless quintessence scalar field whose scalar potential has the exponential form. In this setup, we obtain six critical points among which there is a scalar-field’s kinetic dominated solution which describes both inflationary and late-time era related to the scalar potential parameter. In our model, we also show that the three parameters, namely the scalar potential parameter, the baryotropic parameter, and the Rastall parameter, become bifurcation parameters which determine the stability of the critical points.
Quantum tunneling in the early universe: stable magnetic monopoles from metastable cosmic strings
Authors: Lazarides George , Maji Rinku , Shafi Qaisar 
Published: May 2024

Abstract
We present a novel mechanism for producing topologically stable monopoles (TSMs) from the quantum mechanical decay of metastable cosmic strings in the early universe. In an SO(10) model this mechanism yields TSMs that carry two units (4π/e) of Dirac magnetic charge as well as some color magnetic charge which is screened. For a dimensionless string tension parameter Gμ ≈ 10-9-10-5, the monopoles are superheavy with masses of order 1015-1017 GeV. Monopoles with masses of order 108-1014 GeV arise from metastable strings for Gμ values from ∼ 10-22 to 10-10. We identify the parameter space for producing these monopoles at an observable level with detectors such as IceCube and KM3NeT. For lower Gμ values the ultra-relativistic monopoles should be detectable at Pierre Auger and ANITA. The stochastic gravitational wave emission arise from metastable strings with Gμ ∼ 10-9-10-5 and should be accessible at HLVK and future detectors including the Einstein Telescope and Cosmic Explorer. An E
6 extension based on this framework would yield TSMs from the quantum mechanical decay of metastable strings that carry three units (6π/e) of Dirac magnetic charge.
SKA sensitivity for possible radio emission from dark matter in Omega Centauri
Authors: Wang Guan-Sen , Chen Zhan-Fang , Zu Lei , Gong Hao , Feng Lei , Fan Yi-Zhong 
Published: May 2024

Abstract
Omega Centauri, the largest known globular cluster in the Milky Way, is believed to be the remains of a dwarf galaxy's core. Giving its potential abundance of dark matter (DM), it is an attractive target for investigating the nature of this elusive substance in our local environment. Our study demonstrates that by observing Omega Centauri with the SKA for 100 hours, we can detect synchrotron radio or Inverse Compton (IC) emissions from the DM annihilation products. It enables us to constrain the cross-section of DM annihilation down to ∼ 10-30 cm3 s-1 for DM mass from several GeV to 100 GeV, which is much stronger compared with other observations. Additionally, we explore the axion, another well-motivated DM candidate, and provide stimulated decay calculations. It turns out that the sensitivity can reach g
aγγ ∼ 10-10 GeV-1 for 2 × 10-7 eV< ma < 2 × 10-4 eV.
Hysteresis of European summer precipitation under a symmetric CO2 ramp-up and ramp-down pathway
Authors: Im Nari , Kim Daehyun , An Soon-Il , Paik Seungmok , Kim Soong-Ki , Shin Jongsoo , Min Seung-Ki , Kug Jong-Seong , Oh Hyoeun 
Published: May 2024

Abstract
This study investigates the mechanism of the hysteresis of European summer mean precipitation in a CO2 removal (CDR) simulation. The European summer mean precipitation exhibits robust hysteresis in response to the CO2 forcing; after decreasing substantially (∼40%) during the ramp-up period, it shows delayed recovery during the ramp-down period. We found that the precipitation hysteresis over Europe is tied to the hysteresis in the Atlantic Meridional Overturning Circulation (AMOC). During the ramp-down period, an anomalous high surface pressure circulation prevails over Europe. The anomalous high pressure system is a baroclinic response of the atmosphere to strong North Atlantic cooling associated with a weakened AMOC. This anomalous circulation suppresses summertime convective activity over the entire Europe by decreasing near-surface moist enthalpy in Central and Northern Europe while increasing lower free-tropospheric temperature in Southern Europe. Our findings underscore the need to understand complex interactions in the Earth system for reliable future projections of regional precipitation change under CDR scenarios.
Cone-restricted information theory
Authors: George Ian , Chitambar Eric 
Published: May 2024

Abstract
The max-relative entropy and the conditional min-entropy of a quantum state plays a central role in one-shot and zero-error quantum information theory. One attractive feature of this quantity is that it can be expressed as an optimization over the cone of positive semidefinite operators. Recently, it was shown that when replacing this cone with the cone of separable operators, a new type of conditional min-entropy emerges that admits an operational interpretation in terms of communicating classical information over a quantum channel. In this work, we explore more deeply the idea of building information-theoretic quantities from different base cones and determine which results in quantum information theory rely upon the positive semidefinite cone and which can be generalized. In terms of asymptotic information processing, we find that the standard equipartition properties break down if a given cone fails to approximate the positive semidefinite cone sufficiently well. We also show that the near-equivalence of the smooth max and Hartley entropies breaks down in this setting. We present parallel results for the extended conditional min-entropy, which requires extending the notion of k-superpositive channels to superchannels. On the other hand, we show that for classical-quantum states the separable cone is sufficient to re-cover the asymptotic theory, thereby drawing a strong distinction between the fully and partial quantum settings. We also present operational uses of this framework. We show that the cone restricted min-entropy of a Choi operator captures a measure of entanglement-assisted noiseless classical communication using restricted measurements. We also introduce a novel min-entropy-like quantity that captures the conditions for when one quantum channel can be transformed into another using bistochastic pre-processing. Lastly, we relate this framework to general conic norms and their non-additivity. Throughout this work, we concretely study generalized entropies in resource theories that capture locality and resource theories of coherence/Abelian symmetries.
Tribological investigations of water-based lubricants for application in the deep drawing process
Authors: Behrens B-A , Hübner S , Wehmeyer J , Müller P. , Yarcu S 
Published: May 2024

Abstract
This paper describes the tribological investigation of water-based lubricants in the context of a deep drawing process. Therefore, different methods were conducted in order to determinate the suitability of these lubricants for a deep drawing process. Three lubricant manufacturers each provided their lubricants as part of this work. The sheet materials investigated are an aluminum material (AA6014) and two steel materials (DC04, DP800), each with a thickness of 1.5 mm. All sheet materials were examined in the as-delivered condition as part of this work. The hypothesis for this research proposal is that it is possible to achieve comparable tribological properties in sheet metal forming using water-based lubricants as when using mineral oil-based lubricants. The aim is to optimize a tribological system for water-based lubricants when used as additional lubrication in order to replace mineral oil-based lubricants and, as a result, to shorten the representative process chain by one process step (cleaning). In the course of this work, topographical measurements of the sheet materials were carried out in order to investigate the lubricant holding capacity of the sheet materials. Furthermore, strip drawing tests were performed to determine the friction coefficients of the different lubricant-sheet combinations. The final step was to conduct deep-drawing tests to determine the limits of use of the water-based lubricants by continuously increasing the holding-down force.
Clarification of appropriate conditions for forming complex shapes with multiple steps in two-stage deep drawing process
Authors: Nakamura Shuki , Ichikawa Takeshi , Ishihara Masato , Konishi Haruyuki 
Published: May 2024

Abstract
In this study, appropriate conditions for forming complex shapes with multiple steps, such as automotive side door inner in a two-stage deep drawing process are investigated, and the effectiveness of the process is verified in a test. In this forming process, the inner area of the part is formed in the first stage and the outer area is formed in the second stage. And in the second stage, a forming pad is used to reduce strain in the inner area that is formed in the first stage. The results of the forming test showed that it is necessary to control the blank holding force (BHF) and the pad force (PF) in the second stage to avoid blank ruptures in all areas. Therefore, the concept of the BHF and PF for blank rupture risk at each site was studied using the finite element method (FEM). An appropriate range of BHF and PF was estimated from the results of FEM and the validity of the estimated values was confirmed in an actual test. In addition, it was confirmed that a two-stage deep drawing process using the above appropriate values can form a more severe shape than a one-stage deep drawing process.
The influence of intrinsic formability parameters on the sheared-edge ductility of 120K-class AHSS
Authors: Yim Gihak , Kim Jiyoung , Jeon Jinhwa , Hyun Joosik , Hance Brandon M 
Published: May 2024

Abstract
With enduring versatility, advanced high-strength steels (AHSS) play an increasingly important role in securing automotive safety, performance and sustainability targets in future automotive architectures. However, local formability (resistance to cracking) is of specific relevance to AHSS, and various intrinsic fracture-related concepts have emerged with the goal of understanding and improving the local formability of AHSS (sheared-edge ductility, bendability). This analysis is focused on the relationships between intrinsic formability parameters and other laboratory-scale performance indicators—i.e. the ISO 16630 hole expansion ratio (HER). Included is the AHSS material with minimum tensile strength designation above 1.2GPa: 120K-class 3rd generation AHSS. Additionally, the impact of material property uniformity on HER, and local toughness concept based on the true fracture strain is explored.
Tool surface texturing by shot peening: initial results and lessons learned
Authors: de Argandoña Eneko Sáenz , Mendez Markel , Mendiguren Joseba , Zabala Alaitz 
Published: May 2024

Abstract
Abrasive and adhesive wear is a major issue in sheet metal forming processes. Although different solutions exist to reduce its impact, there is still room for progress. Surface texturing presents a big potential for tribological behaviour improvement by introducing oil retention voids on the surface. However, the economic efficiency of the surface functionalization is paramount for its implementation in industrial processes. In the present study, a widely known technology, shot peening, is applied for the creation of the voids. A grinding+polishing process is then applied to ensure a flat load bearing area. The textures are generated in 1.2379 tool steel blocks hardened at 60 HRc that emulate the tool. Different shot peening strategies are evaluated by carrying out strip drawing tests with AA5754H111 aluminium alloy sheets. Contact pressures up to 25 MPa are applied and the adhesive wear reduction potential is evaluated. First results point out the potential of this solution although the applied shot peening strategy needs to be carefully defined.
Sustainable tool technology: Wood-based forming tools for deep drawing of sheet metal
Authors: Geueke Michael , Steinheimer Rainer , Frohn-Sörensen Peter , Schiller Michael , Engel Bernd 
Published: May 2024

Abstract
In order to improve adaptability to evolving manufacturing processes in an era marked by mass customization and individualization, while also meeting geopolitical climate objectives, it is necessary to employ more sustainable methods in sheet metal forming to enhance flexibility. Metal based rigid tooling systems require a lot of material and energy resources, when aiming for high flexibility and scalability with respect to small batch size production. To reduce the overall resource consumption and to meet climate restrictions, non-metallic tooling approaches can counteract these issues when aiming for individualization in sheet metal forming. Compared to conventional metal-based tooling approaches, wood-based forming tools may enable a potential resource reduction (e.g., carbon footprint) and offer an alternative tooling approach for sheet metal forming. Although the mechanical performance of wood is lower compared to conventional tooling steel, certain wood-based forming tools can potentially be implemented for sheet metal forming. In this work a feasibility study of wood-based tooling materials is executed to investigate the mechanical performance on drawn sheet metal parts in a deep drawing operation. Different composite structures are investigated for wooden forming tools of black locust (robinia pseudoacacia).
Anisotropic-asymmetric mechanical behaviour for an Mg-Gd-Y alloy under various temperatures: Experiment and modelling
Authors: Wu P , Lou Y , Chen Q 
Published: May 2024

Abstract
The study focuses on the anisotropic-asymmetric behaviour of an Mg-Gd-Y alloy at the temperature range of 25∼300 °C. The mechanical experiments were carried out, including the uniaxial tension and compression specimens along rolling direction (RD), diagonal direction (DD), and transverse direction (TD). The deformation behaviour of all specimens was recorded through adopting the digital image correlation technology, obtaining the corresponding force-stroke curves. It is obviously seen that the variation of true stress-plastic strain curve is related with the coupling effect of temperature and strain. The Mg-Gd-Y alloy possesses the remarkable tension-compression asymmetry and anisotropy under various temperatures. A SVT model is proposed to characterize the temperature-related plastic flow behaviour under various loading condition. The evolution of yield loci at different equivalent plastic strain levels and temperatures of the Mg-Gd-Y alloy is accurately characterized by the A-Yoon2014.
Deep drawing simulation of dual phase steel using hardening curves and anisotropic parameters from uniaxial and biaxial tensile tests
Authors: Shrivastava Archit , Kumar D Ravi 
Published: May 2024

Abstract
Among the various factors, the accuracy of the predictions from the numerical simulation of sheet metal forming processes depends on the material model used to define the mechanical behavior of the blank material. The coefficients of the hardening model to define the flow curve and the plastic strain ratios are commonly determined using the uniaxial tensile tests. The advanced anisotropic yield criteria incorporate material flow behaviour and plastic strain ratio in equi-biaxial tension. In this work, deep drawing of a flat bottom cylindrical cup has been simulated using dual-phase steel (DP600) sheets. The biaxial material properties obtained by conducting hydraulic bulge test and cruciform specimen test are used in the anisotropic yield criteria in the simulations. The hardening curves are extrapolated using different hardening laws in which the coefficients are determined from the stress-strain curves obtained from both uniaxial tensile and hydraulic bulge tests. The predicted peak drawing load and thickness variation in the drawn cups are compared with the experimental results of deep drawing.