bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tilt-to-length coupling in LISA—uncertainty and biases
Authors: Hartig M-S , Marmor J , George D , Paczkowski S , Sanjuan J 
Published: January 2025

Abstract
The coupling of the angular jitter of the spacecraft and their sub-assemblies with the optical bench and the telescope into the interferometric length readout will be a major noise source in the LISA mission. We refer to this noise as tilt-to-length (TTL) coupling. It will be reduced directly by realignments, and the residual noise will then be subtracted in post-processing. The success of these mitigation strategies depends on an accurate computation of the TTL coupling coefficients. We present here a thorough analysis of the accuracy of the coefficient estimation under different jitter characteristics, angular readout noise levels, and gravitational wave sources. We analyze in which cases the estimates degrade using two estimators, the common least squares estimator and the instrumental variables estimator. Our investigations show that angular readout noise leads to a systematic bias of the least squares estimator, depending on the TTL coupling coefficients, jitter and readout noise level, while the instrumental variable estimator converges to an unbiased result as the data set length increases. We present an equation that predicts the estimation bias of the least squares method due to angular readout noise.
Efficient surface plasmonic vortex based on multi-arm Archimedes-spiral slot
Authors: Zhong Yang-wan , Wu Liang , Li Wen-hao , Xiao Qing-sheng , Xiao Shi-lei 
Published: January 2025

Abstract
An efficient and small volume surface plasmonic vortex (PV) based on multi-arm Archimedes-spiral slot with different spiral slot parameters m is proposed and investigated. By adding an auxiliary nanocavity under the primary Archimedes-spiral slot, the surface plasmonic polaritons can be efficiently transmitted inward to form surface PV inside the multi-arm Archimedes-spiral slot. The unidirectional excitation of the surface plasmonic polaritons can be achieved by numerically optimizing the geometrical parameters of the auxiliary nanocavity with the finite-difference time-domain method. The proposed multi-arm Archimedes-spiral slot can control the topological charge of the PV generated inside the Archimedes-spiral slot. When illuminated with circularly polarized beam, the relative strength of the primary ring can reach a maximum of 1.97 times as much as that when the auxiliary nanocavity is not provided. This structure can reduce the background noise and significantly improve the integration of nanophotonic circuits. The proposed structure is of great significance for the development of microparticle manipulation technology and the improvement of the integration of future photonic devices.
Effect of combined temperature and pressure variations on the PDIV of wedge-shaped, dielectric-bounded air gaps
Authors: Färber R , Šefl O , Franck C M 
Published: January 2025

Abstract
The variation of the partial discharge inception voltage (PDIV) of wedge-shaped, dielectric-bounded air gaps under concurrent changes of air pressure (7.5 mbar to 950 mbar) and temperature (23 ∘C to 110 ∘C) is investigated in this paper. Two coating materials featuring distinctly different variations of their dielectric permittivity with temperature are used. The experimentally observed variation of the PDIV is shown to be in good agreement with a physical parametrization of the PDIV in terms of the general scaling parameter

p
T

⋅

s

ε
r

. The simplicity of the suggested parametrization makes it a powerful tool for insulation design considerations under a wide range of environmental conditions (pressure p and temperature T) and insulation configurations (insulation thickness s and dielectric permittivity ɛ
r), in particular for (more) electric aviation.
Precise calibration for error detection and correction in material extrusion additive manufacturing using digital fringe projection
Authors: Keller W , Girard J , Goldberg M W , Zhang S 
Published: January 2025

Abstract
This work proposes a novel calibration method to align the coordinate system of a digital fringe projection system and a material extrusion additive manufacturing machine for in-process error detection and correction. A calibration geometry is printed and measured with the DFP system. Three-dimensional and two-dimensional data processing techniques are then implemented to estimate a rigid transformation matrix between the coordinate systems. The proposed calibration method and geometry are designed to run every time before the start of the manufacturing process. This removes inaccuracies caused by processes in additive manufacturing such as homing and auto-leveling, and allows the transformation to have a high accuracy. The proposed calibration method has achieved a sub-millimeter accuracy with an average root mean square error (RMSE) of 0.028 mm. The proposed method was further used for process monitoring to detect and correct sub-layer under-extrusion errors on a layer-by-layer basis. This error correction process improved the average RMSE by a factor of 1.7 for a simple shape error.
On a deep analysis of the reference time of multi-GNSS final and real-time precise clock products with respect to UTC
Authors: Zhang Dong , Zheng Fu , Shi Chuang , Wang Zhen , Ren Fulong , Fan Lei , Hu Zhongshun 
Published: January 2025

Abstract
The underlying reference time of International GNSS Service (IGS) clock products is extensively used in the characteristic analysis of on-board oscillators and precise point positioning timing services. As a reference time used in timing applications, traceability to coordinated universal time (UTC) and high-performance of frequency stability are essential. In this study, based on global navigation satellite system (GNSS) observations from timing laboratories and Circular T published by the Bureau International des Poids et Mesures, the time deviation with respect to UTC and frequency stability are evaluated for the reference time of IGS precise clock products. To comprehensively investigate the performance of the GPS, Galileo, and BeiDou-3 (BDS-3) reference time in the IGS products, five multi-GNSS experiment (MGEX) final products (COM, ESM, GBM, Information and Analysis Centre (IAC), and WUM), two real-time (RT) products (Wuhan University (WHU)-RT and CNES-RT), and the IGS final products are selected for analysis. The results indicate that the GPS reference time of most MGEX products is derived from the broadcast GPS system time (GPST), and the consistency with UTC is within 8 ns over a year. The COM, ESM and WUM define the Galileo and BDS-3 reference time by estimating the inter-system bias as a constant while the Galileo and BDS-3 reference time of GBM and IAC is derived from the broadcast Galileo system time (GST) and BDS system time (BDT). Benefited from the well-performance of GPST, the BDS-3 and Galileo reference time of COM and ESM shows the best performance for the time deviation from UTC. For the RT products, the deviation between the reference time and UTC is within 7 ns for GPS, whereas the peak-to-peak values of the time deviation of BDS-3 and Galileo exceed 15 and 30 ns for nearly two months, respectively. The frequency stability of GPS reference time in most final products can achieve 1.4–5.0 × 10−14, 3.2–5.9 × 10−15 and 3.3–5.3 × 10−15 with the averaging time of 120, 10 020 and 608 400 s, respectively. In addition, the frequency stability of Galileo and BDS-3 reference time is comparable to that of GPS reference time. However, the stability of the reference time of the RT products is inferior to that of the MGEX products, especially for short- and mid-term stability.
Parametric study on the role of energy and mobility on abnormal grain growth in systems undergoing complexion transition
Authors: De Partha Sarathi , Vadlamani Subramanya Sarma , Vedantam Srikanth 
Published: January 2025

Abstract
Despite many decades of research, the exact mechanism contributing to the persistence of abnormal grain growth (AGG) is poorly understood. In many materials, a structural transition at grain boundary (GB), known as complexion transition, has been suggested as a cause of AGG. However, the precise link between complexion transitions and AGG is still unclear and challenging to study experimentally. Recently, we proposed a thermodynamically consistent complexion transition model and using a phase field study we demonstrated persistent AGG induced by the proposed model. Building on our earlier research, this work aims to clarify the relationship between induced grain growth and the underlying complexion transitions. Complexion transitions can be characterized by their type, which is defined by changes in GB properties such as mobility and energy, and their likelihood of occurrence. By systematically varying the type and likelihood of these transitions, we map the development of microstructure and identified the parameter space for occurrence of AGG through two-dimensional phase-field simulations. Quantitative analysis of relative growth of abnormal grains provides valuable insights into the role of complexion transition parameters on AGG. The findings from this study can contribute to a better understanding of the relationship between processing parameters and microstructure during complexion transitions.
Exploring the coupled effects of interfaces and grain size gradients in heterogeneous laminate and gradient structures via a multiple mechanism based constitutive model
Authors: Wang Chun , Liu Eryong , Liu Hanyuan , Yuan Rui 
Published: January 2025

Abstract
As two promising types of heterogeneous materials, gradient structures and heterogeneous laminates possess superior mechanical properties, such as a combination of high strength and exceptional ductility, which can be attributed to back stress strengthening and strain hardening arising from their heterogeneous microstructures. Recent efforts have been made to combine these two unique microstructures to further improve their properties and performance. However, how heterogeneous interfaces and grain size gradients interplay with each other remains unknown. Therefore, this work aims at exploring the coupled effects of interfaces and grain size gradients in copper–bronze heterogeneous laminate and gradient samples via multiple mechanism-based constitutive modeling incorporating statistically stored dislocations, geometrically necessary dislocations, back stress and deformation twinning. It is revealed that different grain size gradients have profound influence on the deformation mechanisms and mechanical behaviors of the material: a monotonic grain size gradient in the copper layers strengthens the material yet reduces its ductility as a result of diminished back stress hardening due to weakened interface effects; a symmetric grain size gradient in the bronze layers leads to an increase in ductility and a decrease in strength; only by introducing a symmetric grain size gradient into the copper layers can the strength and ductility of the material be improved simultaneously, which is accredited to stronger back stress and grain boundary strengthening due to the synergistic effects between the interfaces and the grain size gradients. In addition, the distinct propensities for twinning in the copper and bronze layers can be attributed to both their different stacking fault energies and grain sizes.
A computational study of novel CsYMSe3 (M = Cd, Zn) materials: for their potential optoelectronic and thermoelectric application
Authors: Khan Muhammad Salman , Gul Banat , Aziz Siti Maisarah , Mohamed Abdelhay Salah , Abbas Faheem 
Published: January 2025

Abstract
The thermoelectric performance and adjustable optical properties of chalcogenides are noteworthy. Density functional theory is employed to study the electrical, optical, and thermoelectric properties of the novel CsYMSe3 (M = Cd, Zn) quaternary chalcogenides. A direct band gap nature was predicted based on the band profile study. Using Perdew–Burke–Ernzerhof generalized gradient approximation and TB-modified Becke–Johnson, the reported band gaps are 2.12 and 2.92 eV for CsYZnSe3 and 2.11 and 3.07 eV for CsYCdSe3, respectively. The results showed that in both materials, the hybridization of the orbital Cs–p/d and the Se–p were responsible for direct energy losses. The complex dielectric function and the important linear optical parameters were investigated for possible usage in optoelectronic devices. These materials exhibit stronger absorption of photons. These materials could be employed as particularly effective UV-reflecting materials from the noticed peaks in the reflectivity spectra. Because of their negative Seebeck coefficient values, both materials show n-type conductivity across the whole temperature range. CsYZnSe3 possesses better electrical conductivity than CsYCdSe3, which results in a larger ZT value.
Deep proximal gradient network for absorption coefficient recovery in photoacoustic tomography
Authors: Zheng Sun , Ranran Geng 
Published: January 2025

Abstract

Objective. The optical absorption properties of biological tissues in photoacoustic (PA) tomography are typically quantified by inverting acoustic measurements. Conventional approaches to solving the inverse problem of forward optical models often involve iterative optimization. However, these methods are hindered by several challenges, including high computational demands, the need for regularization, and sensitivity to both the accuracy of the forward model and the completeness of the measurement data. The aim of this study is to introduce a novel learned iterative method for recovering spatially varying optical absorption coefficients (OACs) from PA pressure measurements. Approach. The study introduces a deep learning-based approach that employs the proximal gradient descent mechanism to achieve optical inversion. The proposed framework consists of multiple cascaded structural units, which iteratively update the absorption coefficients through a learning process, unit by unit. Main results. The proposed method was validated through simulations, phantom experiments, and in vivo studies. Comparative analyses demonstrated that the proposed approach outperforms traditional nonlearning and learning-based methods, achieving at least 12.85% improvement in relative errors, 3.50% improvement in peak signal-to-noise ratios, and 3.53% improvement in structural similarity in reconstructing the OAC distribution. Significance. This method significantly improves the accuracy and efficiency of quantitative PA tomography. By addressing key challenges such as computational demand and sensitivity to the accuracy of the forward model and the completeness of the measurement data, the proposed framework offers a more reliable and efficient alternative to traditional methods, with potential applications in medical imaging and diagnostics.
Experimental characterization of turbulence properties in negative triangularity DIII-D plasmas
Authors: Stewart Samuel David , McKee G. R. , Chrystal Colin , Cote Tyler , Geiger Benedikt , Khabanov Filipp , Nelson Andrew Oakleigh , Qin Xijie , Paz-Soldan Carlos , Schmitz Lothar , Thome Kathreen E , Yan Z 
Published: January 2025

Abstract
Negative Triangularity (NT) plasmas have demonstrated robustly ELM-free high-performance operation and provide a unique testbed to study how plasma shaping affects turbulent transport. The Beam Emission Spectroscopy (BES) diagnostic provides localized 2D measurements of low-k ($k_{\theta} \rho_s < 1$) density fluctuations. In a sweep of upper triangularity at fixed power, H-mode access is suppressed and an NT-edge is observed. The turbulence amplitude ($\tilde{n}/n$) is shown to decrease by $\sim50\%$ for $\rho<0.9$ in the NT-edge phase as compared to the H-mode phase. Additionally, low-velocity edge modes below 70 kHz are suppressed by triangularity and the dominant mode propagating in the electron diamagnetic direction is seen to broaden in wavenumber space in the NT-edge phase. In a strong NT plasma ($\delta_{avg}\sim-0.5$), low amplitude modes ($\tilde{n}/n <0.5\%$) propagating in the ion-diamagnetic direction with radially-poloidally symmetric eddy structure are identified for $\rho \sim 0.65-0.83$ consistent with Ion Temperature Gradient (ITG) turbulence. Modes consistent with Trapped Electron Mode (TEM) turbulence are observed propagating in the electron-diamagnetic direction for $\rho\gtrsim0.83$ with poloidally extended eddy structure and reduced amplitudes observed at the separatrix. The turbulence properties presented in this paper help validate our understanding of NT turbulence and help explain the improved confinement and unique edge features of NT plasmas.
Machine learning enhanced tomographic reconstruction for multispectral imaging on TCV
Authors: van Leeuwen Loek , Schoukens Maarten , Citrin Jonathan , van Berkel Matthijs , Duval Basil , Perek Artur ,   the TCV Team
Published: January 2025

Abstract
A multispectral camera setup is used to infer a 2D map of plasma parameters in a tokamak from spectral emissions. However, the light measured by these cameras is line integrated in the toroidal direction, whereas emissivities on the poloidal plane are necessary for the inference. The poloidal plasma emissivity can be obtained by tomographic reconstruction, but classical techniques are too slow to use these emissivities for real-time control. We present two machine learning based approaches to accelerate the reconstruction of the poloidal emissivities from line integrated data measured by the camera setup. Both approaches yield more accurate results on synthetic data than the iterative approach while being, with the right implementation, fast enough for real-time control applications.
Measurement of the flexoelectric coefficients in van der Waals materials with separation of piezoelectricity
Authors: Liang Chaobo , Wang Tingjun , Cui Yuanyuan , Chen Yichong , Du Guoshuai , Chen Yabin , Wang Xueyun , Lun Yingzhuo , Hong Jiawang 
Published: January 2025

Abstract
The flexoelectric coefficient is a key material parameter describing the interaction between the electric polarization and strain gradient, which is of significance to design high-performance flexoelectric devices. The macroscopic cantilever bending and truncated pyramid compression are common approaches to measure the flexoelectric coefficients of bulk materials. However, these conventional methods are challenging for the small-sized van der Waals (vdW) materials that have recently emerged in the field of flexoelectricity, especially for piezoelectric ones to separate flexoelectric and piezoelectric contribution. In this work, we design vdW materials-embedded multilayer structures for accurately measuring its flexoelectricity. An oscillatory four-point bending deformation is applied to the multilayer structures and induces stable flexoelectric current. Combined with a theoretical model, the contribution of the piezoelectricity is separated through measuring the current variation among the multilayer structures in which the vdW material is embedded in different plane position. The flexoelectric coefficients of two typical vdW materials, piezoelectric CuInP2S6 and non-piezoelectric 2H-MoS2, are measured as −25.6 nC m−1 and 174.1 nC m−1, respectively. And large flexocoupling coefficients are found in both vdW materials. This work provides a new method for the intrinsic flexoelectric measurements of small-sized vdW materials with separating piezoelectric contribution and brings new insights into the exploration of high-performance flexoelectric materials.
4D printing of generative AI-assisted designs
Authors: Nafea Marwan 
Published: January 2025

Abstract
This paper presents, for the first time, the concept of four-dimensional (4D) printing of actuators that are designed using a generative artificial intelligence (AI) tool. The generative AI tool used in this work is Ideogram, which is a text-to-image tool that allows creating images based on the user’s prompts. These prompts are carefully formulated to assess the ability of Ideogram to generate designs that have uniform shapes with uniform infill patterns, uniform shapes with nonuniform infill patterns, and nonuniform shapes with nonuniform infill patterns. Two prompts are used to address each case in a different way, adding up to a total of six prompts. Each prompt is used to generate four different images that are used as designs. This process is followed by extracting each design’s path using Inkscape and exporting it to SolidWorks. Each design is then sliced using two different approaches via Simplify3D, which leads to the development of 48 designs. The first method prints the passive parts of the actuator with a 100% infill and the active parts with a 0% infill (except for a single outline perimeter), while the second uses a 100% infill for both parts. The designs are then 4D printed from polylactic acid (PLA) using fused deposition modeling and then activated in hot water. The bending performance of the activated PLA actuators is then characterized using Kinovea. The different approaches of printing cause the bending performance to be significantly altered. Therefore, the bending angles of these designs range from 9.3° to 72.8°, while the directions of bending range from 0° to 170°. The developed designs in this work demonstrate complex bending performance due to the randomness of the directions of the induced strain during the printing process. The results illustrate that the proposed concept in this work is promising for various types of 4D printing applications that require developing complex and creative designs, offering new possibilities for 4D printing where standard design methods may fall short.
Design, construction and test of a 13 T no-insulation REBCO magnet: validation of an improved circuit model considering the screening current
Authors: Zheng Hengkang , Wang Yijun , Liu Mengyu , Song Yunxing , Li Liang 
Published: January 2025

Abstract
No-insulation (NI) (RE)Ba2Cu3O
y
(REBCO (RE = Rare Earth)) magnets show great potential in producing ultra-high magnetic field due to their excellent self-protection behaviors, high current density, and compact structure. However, the complexity of their fabrication process, along with the intrinsic screening current induced in the coated REBCO layer, poses challenges for large-scale applications. The screening current not only generates an unwanted irregular magnetic field and overstress, but also leads to a non-uniform current distribution within winding, affecting the inductance and dynamic voltages of NI REBCO magnets. To accurately simulate the electromagnetic behaviors of each pancake coil in an NI REBCO magnet, we propose an improved network circuit integrated with the homogenous T-A formulation model. This model accounts for the screening current and simulates the detailed electromagnetic characteristics of each pancake coil without the need for pre-calculating the current-dependent inductance matrix. A 13 T NI REBCO superconducting magnet was developed for high-frequency gyrotrons in our lab. The design, construction and energizing test of this magnet are presented. The accuracy and validity of the improved circuit model are verified by comparing experimental voltage measurement with simulated results with or without considering the screening current. The voltage data reveals significant dynamic drift during the low-current ramping stage, attributed to the temporal changes in the screening current before it reaches saturation.