bluuebunny/crossref_metadata_2025 huggingface dataset:
Chiral media and optical rotatory dispersion by means of a simple polarimetric experiment for undergraduate students
Authors: Cortés Pablo , Piquero Gemma , G de Sande J Carlos
Published: July 2024

A simple experiment taking into account media with natural optical activity and their characterization by means of Mueller polarimetry is proposed for undergraduate Optics and Photonics laboratories. The objectives are, first, to review how to characterize dielectric and homogeneous media with natural optical activity by means of a Mueller matrix, taking into account the variation of these characteristics with wavelength, and combining concepts such as polarimetry, natural optical activity, and rotatory dispersion. Secondly, a complete and simple experiment is proposed to characterize a chiral medium by means of its Mueller matrix for different wavelengths. This experiment can be performed by undergraduate students in a standard optics laboratory. As a particular example of a chiral medium, a quartz crystal is used. The experimental results are compared with those published for crystalline quartz to validate the experiment.
Solving Bayesian inverse problems with expensive likelihoods using constrained Gaussian processes and active learning
Authors: Dinkel Maximilian , Geitner Carolin M , Robalo Rei Gil , Nitzler Jonas , Wall Wolfgang A
Published: July 2024

Solving inverse problems using Bayesian methods can become prohibitively expensive when likelihood evaluations involve complex and large scale numerical models. A common approach to circumvent this issue is to approximate the forward model or the likelihood function with a surrogate model. But also there, due to limited computational resources, only a few training points are available in many practically relevant cases. Thus, it can be advantageous to model the additional uncertainties of the surrogate in order to incorporate the epistemic uncertainty due to limited data. In this paper, we develop a novel approach to approximate the log likelihood by a constrained Gaussian process based on prior knowledge about its boundedness. This improves the accuracy of the surrogate approximation without increasing the number of training samples. Additionally, we introduce a formulation to integrate the epistemic uncertainty due to limited training points into the posterior density approximation. This is combined with a state of the art active learning strategy for selecting training points, which allows to approximate posterior densities in higher dimensions very efficiently. We demonstrate the fast convergence of our approach for a benchmark problem and infer a random field that is discretized by 30 parameters using only about 1000 model evaluations. In a practically relevant example, the parameters of a reduced lung model are calibrated based on flow observations over time and voltage measurements from a coupled electrical impedance tomography simulation.
Lithographically patternable SU-8/Graphene nanocomposite based strain sensors for soft-MEMS applications
Authors: Beigh Faizan Tariq , Beigh Nadeem Tariq , Mallick Dhiman
Published: July 2024

This paper presents an optimized, lithographically patternable SU-8/Graphene nanocomposite based piezoresistive strain sensor for localized, high-precision assessment, which marks a significant advancement in the field of soft-MEMS based technologies. The fabrication process involves the photolithography of a SU-8/Graphene nanocomposite with a minimum resolution of 50 μm, resulting in a material with excellent electrical conductivity and mechanical properties. Specifically, a 3% SU-8/Graphene composition was chosen to exceed the percolation threshold, enabling substantial changes in the resistance

%Δ
R

/

R

and facilitating photopatternability. The sensor exhibited exceptional performance characteristics, including a rapid response time of 0.1 s and a wide bending range from 0° to 60°. Notably, it demonstrated a remarkable %ΔR/R of 19.21, indicating its superior sensing capability. Such high sensitivity is crucial for applications that require precise, localized measurements, such as biomedical engineering, sports science, and smart healthcare.
A method for estimating the rotation errors of BDS broadcast ephemeris using global satellite laser ranging data
Authors: Gao Weiguang , Zhou Wei , Zhou Shanshi , Chen Guangyao , Huang Yong , Qu Weijing , Hu Xiaogong
Published: July 2024

The BeiDou-3 Navigation Satellite System (BDS-3) generates navigation messages from a regional ground tracking network and inter-satellite links, relying on predicted station coordinates and Earth rotation parameters (ERPs). These procedures, however, may lead to orientation errors in the broadcast ephemeris, termed constellation rotation errors. Traditionally, these errors are monitored through Helmert transformation analysis comparing broadcast and post-processed orbits, a method that highlights discrepancies between the global navigation satellite system (GNSS) terrestrial reference frame (TRF) and the International TRF (ITRF) but suffers from a two-week evaluation delay. This study proposes a near real-time approach for estimating constellation rotation errors using high-precision satellite laser ranging (SLR) data, representing the difference between GNSS TRF and ITRF through the International laser ranging service TRF. The impact of SLR data quantity and distribution on rotation estimation accuracy is investigated, and the effectiveness of this method on BDS-3 orbits with ERP-induced orientation deficiencies is validated. Results show that the root mean square of broadcast orbit errors and the orbit user ranging error reduce from 0.8/0.7/0.2 m to 0.1/0.1/0.1 m, respectively. This demonstrates the method’s capability for real-time monitoring and correcting orientation errors within BDS-3 navigation messages.
Underground coal gangue recognition based on composite fusion of feature and decision
Authors: Li Xiaoyu , Xia Rui , Kang Rui , Li Bo , Wang Xuewen , Liu Tao , Gao Jihong , Li Rui , Xu Wenjun , Cui Weixiu
Published: July 2024

The underground coal gangue separation and in-situ filling can reduce environmental pollution, promote the recycling of resources, and ensure the safe operation of mining. However, the harsh environment and abnormal working conditions are a significant challenge to the separation technology. Therefore, it is essential to develop a coal gangue classification method that is highly accurate, robust, and can handle abnormal working conditions. To address the above problems, this paper innovatively combines spectral modalities with image modalities to establish a multimodal fusion idea of composite fusion. Firstly, the feasibility of spectral-image fusion and effective fusion criterion are explored under the concat fusion strategy through various feature combinations and classification algorithms under ideal conditions to improve the performance of the model; Secondly, feature fusion is introduced into the single-layer perceptron and its potential in deep learning is explored to improve the performance of the model; Then the quantitative criteria of the judgment matrix are improved based on the analytical hierarchy method (AHP) to improve the scientificity and objectivity of decision making; Finally, the effectiveness of our method is verified by testing the bimodal dataset of simulated working conditions. The results show that the accuracy of the composite fusion of spectral and image features reaches 91.43%, and our AHP can be applied to all basic model scenarios, which makes the method highly applicable and feasible. The fusion of deep neural networks shows the strong potential of modal fusion in deep learning. This method can provide a new idea for intelligent separation of underground coal gangue.
Quantifying the surface damage of involute gear flanks independent of the gear datum axis
Authors: Reavie Tom , Frazer Robert
Published: July 2024

Surface damage on involute gear tooth flanks can develop during the operation of a gearbox and affects their life, durability and efficiency. Understanding the extent and severity of this damage is critical, especially in long life applications such as wind turbines where gearboxes are a critical component that incur high down time and costs for replacement. Accessing gears in service is difficult and relating gear form measurements to the gear datum is often impossible without its removal. Additionally, damage measurements are typically not areal, which can miss the most severe areas, or require lengthy measurement times. This paper describes a method for characterising and quantifying localised damage relative to the undamaged tooth surface independent of the gear datum axis, and provides a method to estimate the damage location using involute co-ordinates. By taking soft replicas of the gear flank and measuring them with optical methods, the damage is characterised. This method allows for the areal evaluation of damage that relates to involute coordinates, which can be combined with nominal data or measurements after manufacture to create data sets for simulation in tooth contact analysis models, used to train condition monitoring models or for improved maintenance programming to improve reliability and reduce costly downtime.
Crack configuration influence on fracture behavior and stress shielding: insights from molecular dynamics simulations
Authors: Şen O C , Janisch R
Published: July 2024

The fracture behavior of the Ti–Al alloy is significantly affected by its nano-lamellar structure. However, further investigation is still required to fully comprehend how the initial crack configuration influences the lamellar Ti–Al’s deformation behavior. Although molecular dynamics simulations are a great way to study crack-tip interactions in interface-dominated microstructures, the design of the simulation can have an impact on the behavior that is predicted. To shed light on this matter and at the same time to understand the impact of the specific interface structure, a systematic study of crack-tip interface interactions in nano-lamellar two-phase Ti–Al was carried out. The type of interface and crack configuration were varied in these simulations to distinguish between the effects of the microstructure and the crack geometry. Results show that the semi-coherent pseudo twin (

γ

/

PT) interface is the strongest barrier for crack propagation while the coherent true twin interface (

γ

/

TT) is the weakest. After a thorough review of the contributing factors, it is evident that the orientation of the crack has a greater impact on its propagation than the aspect ratio of the crack. The stress shielding effectiveness of lamellar interfaces is strongly dependent on the crack configuration. However, regardless of the initial crack set-up, the coherent

γ

/

TT interface appears to be the most effective interface in terms of shielding.
Investigation of AlGaN UV emitting tunnel junction LED devices by off-axis electron holography
Authors: Cooper David , Arcara Victor Fan , Damilano Benjamin , Duboz Jean-Yves
Published: July 2024

Here we use off-axis electron holography combined with advanced transmission electron microscopy techniques to understand the opto-electronic properties of AlGaN tunnel junction (TJ)-light-emitting diode (LED) devices for ultraviolet emission. Four identical AlGaN LED devices emitting at 290 nm have been grown by metal–organic chemical vapour deposition. Then Ge doped n-type regions with and without InGaN or GaN interlayers (IL) have been grown by molecular beam epitaxy onto the top Mg doped p-type layer to form a TJ and hence a high quality ohmic metal contact. Off-axis electron holography has then been used to demonstrate a reduction in the width of the TJ from 9.5 to 4.1 nm when an InGaN IL is used. As such we demonstrate that off-axis electron holography can be used to reproducibly measure nm-scale changes in electrostatic potential in highly defected and challenging materials such as AlGaN and that systematic studies of devices can be performed. The LED devices are then characterized using standard opto-electric techniques and the improvements in the performance of the LEDs are correlated with the electron holography results.
A simple, rapid and entertaining method to measure specific heat of metals using liquid nitrogen and Leidenfrost effect
Authors: Dourado F , Barreto J , Bonfait G
Published: July 2024

Taking advantage of the fascination of ‘playing’ with liquid nitrogen, this article proposes a didactical experiment involving the use of this liquid to measure the heat capacity of cylindrical metallic blocks (copper, aluminum, brass, and stainless steel; volume ≈ 20 cm3). It also permits to demonstrate qualitatively and quantitatively the Leidenfrost effect. The experimental setup consists of a low-cost recipient adequate for liquid N2 storage, a multimeter and a weighing scale. The experience starts by a rapid immersion of metallic block in liquid N2 and by measuring simultaneously the block’s temperature and the mass of the evaporated liquid along the cooling process. Knowing the latent heat of the liquid

L

, the evaporated mass

Δ
m

during a temperature variation

Δ
T

, the heat capacity is obtained by

C
p
=
L

 

Δ
m

/

Δ
T

. This method allowed to measure the specific heat in the 100–270 K temperature range in less than 3 min and the results are in quite good agreement with the literature data. On the other hand, the cooling rate, measured by temperature and liquid N2 change, clearly shows two regimes as expected by the Leidenfrost effect and the critical heat flux calculated is in good agreement with previous experiments. Such an experiment can be adapted to various student levels and present a didactical approach to important thermodynamical concepts in parallel with appealing phenomena.
Pencil-drawn tunable electrical resistance and Joule heating demonstration using a smartphone-based thermal imaging camera
Authors: Thakur Aditya Singh , Dubey Shivam , Thakur Abhay Singh , Srivastava Vinit , Vaish Rahul
Published: July 2024

This paper delves into the educational potential of pencil circuits for teaching key electrical concepts. Using both practical experiments and theoretical examinations, this study explores the application of pencil circuits in demonstrating concepts related to series and parallel resistance, Ohm’s law, and Joule’s heating law. By leveraging the simplicity and accessibility of pencil-based setups, students can gain a practical understanding of these fundamental principles. Additionally, the integration of thermal imaging technology enhances the visualization of Joule’s heating law, further enriching the learning experience.
A GPU-accelerated Monte Carlo code, RT2 for coupled transport of photon, electron/positron, and neutron
Authors: Lee Chang-Min , Ye Sung-Joon
Published: July 2024

Objective. This work aims to develop a graphics processing unit (GPU)-accelerated Monte Carlo code for the coupled transport of photon, electron/positron and neutron over a broad range of energies for medical applications. Approach. By separating the MC evolution of radiation into source, transport, and interaction kernels, the branch divergence was alleviated. The memory coalescence was achieved by vectorizing the access pattern in which the secondary particles were archived. To accelerate further particle tracking, ray-tracing hardware acceleration in the Nvidia OptiXTM framework was applied. For photon and electron/positron, the EGSnrc interaction modules were ported as a GPU-optimized configuration. For neutron, a group-wised transport based on NJOY21 preprocessed data was implemented. The developed code was validated against CPU-based FLUKA. Neutron, x-ray and electron beams incident on water and ICRP phantoms were simulated. The neutron energy group and the transport parameters of photon and electron were set to be the same in both codes. A single Nvidia RTX 4090 card was used in this code while all 20 threads of a single Intel Core i9-10900K node were used in FLUKA. Main results. The number of histories was set to ensure that statistical uncertainties lower than 2% for all voxels whose doses were larger than 20% of the maximum. In all cases, the dose differences in the voxels between the codes were within 2.5%. For photons and electrons, the developed code was 150–300 times faster than FLUKA in both geometries. For neutrons, the code was respectively 80 and 135 times faster in the water and ICRP phantoms than FLUKA. Significance. This study offers an appropriate solution for uncoalesced memory access and branch divergence commonly encountered in coupled MC transport on the GPU architecture. The formidable acceleration in computing times and accuracy shown in this study can promise a routine clinical use of MC simulations.
Research and application of omics and artificial intelligence in cancer
Authors: Zhang Ye , Ma Wenwen , Huang Zhiqiang , Liu Kun , Feng Zhaoyi , Zhang Lei , Li Dezhi , Mo Tianlu , Liu Qing
Published: July 2024

Cancer has a high incidence and lethality rate, which is a significant threat to human health. With the development of high-throughput technologies, different types of cancer genomics data have been accumulated, including genomics, epigenomics, transcriptomics, proteomics, and metabolomics. A comprehensive analysis of various omics data is needed to understand the underlying mechanisms of tumor development. However, integrating such a massive amount of data is one of the main challenges today. Artificial intelligence (AI) techniques such as machine learning are now becoming practical tools for analyzing and understanding multi-omics data on diseases. Enabling great optimization of existing research paradigms for cancer screening, diagnosis, and treatment. In addition, intelligent healthcare has received widespread attention with the development of healthcare informatization. As an essential part of innovative healthcare, practical, intelligent prognosis analysis and personalized treatment for cancer patients are also necessary. This paper introduces the advanced multi-omics data analysis technology in recent years, presents the cases and advantages of the combination of both omics data and AI applied to cancer diseases, and finally briefly describes the challenges faced by multi-omics analysis and AI at the current stage, aiming to provide new perspectives for oncology research and the possibility of personalized cancer treatment.
Adaptive local boundary conditions to improve deformable image registration
Authors: Inacio Eloïse , Lafitte Luc , Facq Laurent , Poignard Clair , Denis de Senneville Baudouin
Published: July 2024

Objective. In medical imaging, it is often crucial to accurately assess and correct movement during image-guided therapy. Deformable image registration (DIR) consists in estimating the required spatial transformation to align a moving image with a fixed one. However, it is acknowledged that for DIR methods, boundary conditions applied to the solution are critical in preventing mis-registration. This poses an issue particularly when areas of interest are located near the image border. Despite the extensive research on registration techniques, relatively few have addressed the issue of boundary conditions in the context of medical DIR. Our aim is a step towards customizing boundary conditions to suit the diverse registration tasks at hand. Approach. We analyze the behavior of two typical global boundary conditions: homogeneous Dirichlet and homogeneous Neumann. We propose a generic, locally adaptive, Robin-type condition enabling to balance between Dirichlet and Neumann boundary conditions, depending on incoming/outgoing flow fields on the image boundaries. The proposed framework is entirely automatized through the determination of a reduced set of hyperparameters optimized via energy minimization. Main results. The proposed approach was tested on a mono-modal computed tomography (CT) thorax registration task and an abdominal CT-to-MRI registration task. For the first task, we observed a relative improvement in terms of target registration error of up to 12% (mean 4%), compared to homogeneous Dirichlet and homogeneous Neumann. For the second task, the automatic framework provides results close to the best achievable. Significance. This study underscores the importance of tailoring the registration problem at the image boundaries. In this research, we introduce a novel method to adapt the boundary conditions on a voxel-by-voxel basis, yielding optimized results in two distinct tasks: mono-modal CT thorax registration and abdominal CT-to-MRI registration. The proposed framework enables optimized boundary conditions in image registration without prior assumptions regarding the images or the motion.
A simplex path integral and a simplex renormalization group for high-order interactions
*
Authors: Cheng Aohua , Xu Yunhui , Sun Pei , Tian Yang
Published: July 2024

Modern theories of phase transitions and scale invariance are rooted in path integral formulation and renormalization groups (RGs). Despite the applicability of these approaches in simple systems with only pairwise interactions, they are less effective in complex systems with undecomposable high-order interactions (i.e. interactions among arbitrary sets of units). To precisely characterize the universality of high-order interacting systems, we propose a simplex path integral and a simplex RG (SRG) as the generalizations of classic approaches to arbitrary high-order and heterogeneous interactions. We first formalize the trajectories of units governed by high-order interactions to define path integrals on corresponding simplices based on a high-order propagator. Then, we develop a method to integrate out short-range high-order interactions in the momentum space, accompanied by a coarse graining procedure functioning on the simplex structure generated by high-order interactions. The proposed SRG, equipped with a divide-and-conquer framework, can deal with the absence of ergodicity arising from the sparse distribution of high-order interactions and can renormalize a system with intertwined high-order interactions at the p-order according to its properties at the q-order (

p
⩽
q

). The associated scaling relation and its corollaries provide support to differentiate among scale-invariant, weakly scale-invariant, and scale-dependent systems across different orders. We validate our theory in multi-order scale-invariance verification, topological invariance discovery, organizational structure identification, and information bottleneck analysis. These experiments demonstrate the capability of our theory to identify intrinsic statistical and topological properties of high-order interacting systems during system reduction.
The dynamical evolution of exciton-polaritons in asymmetric ring-step potential well
Authors: Dong Yifan , Ren Yuan , Li Xiuqian , Xiong Zhenyu , Song Tieling , Guo Aolin , Guo Longfei , Li Baili , Liu Peicheng , Wu Hao
Published: July 2024

The exciton-polariton, a quasi-particle formed by the coupling of excitons and photons, exhibits a semi-light-semi-matter nature, inheriting the advantages of both constituents and capable of achieving Bose-Einstein condensation at room temperature. This paper investigates the evolution of superposition states of semiconductor microcavity exciton-polariton Bose–Einstein condensate (BEC) within a ring-shaped structure. By employing theoretical modeling, the time-dependent dynamics of the superposition states of exciton-polaritons bound within a unique asymmetric ring-step potential well structure are analyzed, focusing on halide perovskite semiconductor materials. The study reveals correlations between the potential well structure of this step-like configuration and the transition of exciton-polariton BEC superposition states, shedding light on the evolution paths of BEC systems under specific structural influences and the fluctuation patterns of excitonic fields. These findings hold relevance for experimental manipulations of exciton-polariton superposition states within microcavities. This research demonstrates that ring-step potential well structures influence the excitation and evolution of exciton-polariton BEC superposition states, leading to transitions towards higher or lower order states. This transition is reflected macroscopically in alterations in the number and spatial distribution of interference petals in the superposition states. We consider initial states with orbital angular momentum quantum number l = 2, 3, 4, respectively. By exploiting the different structural relationships of ring-step potential wells, we achieve controlled evolutions of macroscopic occupation states, with interference petal numbers ranging from 4 to 6, 4–8, 6–8, 6–10, 8–10, 8–12, and 6–4.
Construction of fuzzy black holes and self-gravitational droplets in exponential f(R) gravity
Authors: Khan S , Yousaf Z
Published: July 2024

This paper discusses the construction of non-commutative geometry based self-gravitational droplets or fuzzy black holes (BHs) within the context of exponential-f(R) gravity model

1

β

e

β
R

−
1

, where β is a parameter with units [length
2]. Considering the Einasto density profile, a generalization of the Gaussian profile, we extend the noncommutative-inspired mini BH metric to incorporate dark matter (DM) as a constituent of the BH. We investigate various Einasto DM fuzzy objects filled with anisotropic fluid content, considering different values of the shape parameter and rescaled mass. This study investigates the possibility of stable self-gravitational compact objects with fuzzy mass distributions inspired by a well-known DM profile, the Einasto parametrization. These intriguing astrophysical configurations fall into three categories: fuzzy self-gravitational droplets with no event horizon, and fuzzy black holes featuring either one or two horizons. It is important to highlight that all these astrophysical entities are solutions derived from the exponential-f(R) gravity model. The corresponding effective potentials exhibit a significant resemblance to the effective potential of the classical Schwarzschild Black Hole located at the center of the Galaxy. Specifically, we investigate the potential for these black holes to serve as central galactic entities.
A wide angle beam scanning CRLH leaky-wave antenna with non-identical elements per unit-cells
Authors: Zamini H , Afsahi M , Dalili Oskouei H R , Mohammadi Shirkolaei M
Published: July 2024

In this research article, a wide-angle scanning leaky-wave antenna (LWA) based on the composite right/left-handed (CRLH) metamaterial (MTM) operating over the C-band spectrum for mobile applications is proposed, investigated, and realized. The proposed LWA includes nine CRLH-MTM-based unit-cells. The properties of CRLH-MTM have been applied using series slots and shunt metallic via-holes. Each unit cell consists of three patches, two external patches, and one smaller middle patch implemented between them. One slot has been etched on each external patch; the width of these two slots is unequal. Moreover, the distance of the middle patch with each side patch is different. The results show that using this method of realizing non-identical elements caused the achievement of proper return-loss at the transition frequency and provided the balanced CRLH metamaterial condition. Additionally, using CRLH-MTM properties by realizing series capacitance (slot) and shunt inductance (via-holes) made the wide-angle scant from backward to forward radiation pattern. The results demonstrate that the LW antenna with small dimensions of 251.5 × 30 × 1.575 mm3 operates over a frequency range of 4.8–6.13 GHz covering a wide beam scanning range from

−
63

°

to

+
6
5

°

with broadside radiation at the center frequency of 5.46 GHz. The radiation gain of the proposed antenna varies from 6.2–13.1 dB. The achievements confirm the effectiveness of the proposed methods to realize a high-performance LW-antenna with the advantages of simple design, low profile, low cost, and easy of manufacture for mobile applications.
Asymptotics for some logistic maps and the renormalization group
Authors: Faria da Veiga Paulo A , O’Carroll Michael
Published: July 2024

We explain the relation between the r = 1 case of the logistic map x

i+1 = r
x

i
(1 − x

i
),

x

i

∈
R

, i = 0, 1, 2, …, r > 0 and x
0 ≥ 0, and the renormalization group flow arising in the multiscale analysis of interesting zero fixed point, asymptotic free quantum field theory models such as the ultraviolet (1 + 1)-dimensional Gross-Neveu model and QCD, and the infrared

ϕ

4

4

model . We obtain the asymptotics of the mapping, which shows an inverse power decay approach to the fixed point x
* = 0, Gaussian fixed point, with additional logarithmic-like corrections. This asymptotic behavior is independent of the initial condition x
0 ∈ (0, 1) (hence, there is no constraint for x
0 to be small, as usual in quantum field models), and only depends on the lowest orders in a polynomial perturbation. In asymptotic free quantum field theory, this amounts to say that knowing the renormalization group β-function expansion in the coupling constant, up to higher orders, does not improve our knowledge of the asymptotics of the coupling flow. A comparison with a similar differential equation with continuous time is made by analyzing stability of this kind of solution and higher order monomial perturbations. We also obtain the detailed asymptotics for 0 < r < 1. As well, our methods can be applied when r ∈ (1, 3]. It is known, but without detailed asymptotics, that all trajectories with initial condition x
0 ∈ ( − 1, 1) converge to the fixed point x
* = (r − 1)/r. For r = 2, the super attractive case, we obtain an explicit exact solution which exhibits an exploding, non-constant exponential decay rate approach to the x
* = (1/2) fixed point. Our methods include the use of iterations, a discrete version of the Fundamental theorem of Calculus, a discrete version of the integrating factor method for first order linear ODEs and, sometimes, a scaling transformation. To obtain these results, we do not use the traditional Banach contraction mapping theorem, which only provides an upper bound on the asymptotics. We expect that our methods can be employed to determine the asymptotics of the logistic map for a wider range of parameters, where other fixed points are present.
Effect of Al substitution on the electron-phonon interaction for β-Ga2O3
Authors: Bhattacharjee Jayanta , Singh S D
Published: July 2024

The relevant parameters of electron–phonon (e-ph) interaction, like mean phonon temperature and e-ph interaction strength for Al-substituted β-Ga2O3, i.e., β-(AlxGa1–x)2O3 alloys, have been determined from the fitting of the temperature dependence of the band gap using Bose–Einstein empirical model. Both e-ph interaction strength and mean phonon temperature decrease sharply for initial Al compositions; then, they increase slightly and become more or less constant. This is explained by using the already existed concepts of propagon and diffuson for the phonon modes that interact with the electrons. Presence of two sublattices at the local level is found to be the origin of diffuson-like behaviour of phonon modes in β-(AlxGa1–x)2O3 alloyed system, which vibrate independently like a non-propagating oscillator and diffuse through the β-(AlxGa1–x)2O3 lattice. The diffuson-like behaviour of phonon modes in the β-(AlxGa1–x)2O3 alloy is found to be responsible for the reduction in e-ph interaction. The reduction of e-ph interaction strength of β-Ga2O3 with Al substitution may lead to the better performance of power devices working at higher temperatures.
Hysteresis gap-shrinking and structural effects of minor Al and Ti modifications on binary CuAl-based high-temperature shape memory alloys
Authors: Karaduman Oktay , Özkul İskender , Aksu Canbay Canan
Published: July 2024

Cu-based shape memory alloys (SMAs), except for exhibiting shape recovery, superelasticity, and high damping, are desirable because these smart materials have higher electrical and thermal conductivity and much lower prices than NiTi SMAs. However, they also have some downsides in mechanical strength and brittleness (mostly stemming from their coarse grain structure) and thermal instability. Therefore, adding some grain refining elements to these SMAs to improve their shape memory effect (SME), and thermal, structural, and mechanical properties is a widespread and simple way that significantly affects their martensitic phase transitions, structure, and mechanical properties. One of these grain-refining elements is titanium. Its thermal conductivity is lower than those of Cu and Al elements and has a low solubility in Cu-matrix. Besides the effects of small Al variations, the use of minor amounts of titanium in binary CuAl-base alloys can show impressive effects on all characteristics of these shape memory alloys, such as shape memory effect properties, martensitic transformation kinetics parameters, and microstructural features. In this research work, CuAlTi ternary high-temperature shape memory alloys (HTSMAs) with new compositions were produced by the arc melting method without a complicating use of Mn or Ni components in usual ternary CuAlMn and CuAlNi shape memory alloys. Thermal analyses of the prepared samples of the alloys were investigated by using differential scanning calorimetry (DSC) and differential thermal analysis (DTA) measurements. In contrast, x-ray diffraction (XRD) test results and optical micrographs were used for analyzing the structure of the alloy samples. The effect of different amounts of low soluble and grain refining Ti element on the binary CuAl alloy system was investigated.
Effect of void geometry and magnetic anisotropy in controlling the vortex in sub-micron annular Permalloy disc
Authors: Palabindela Praveen , Sinha Jaivardhan , Behera Bhaskar Chandra
Published: July 2024

Ferromagnetic rings, particularly asymmetric Permalloy (Py) rings are recognized as promising configurations for spintronic devices, offering additional degrees of freedom for manipulating magnetic states, especially in vortex configurations. Through micromagnetic simulations, our study explores the impact on magnetization states and spin configuration concerning ring symmetry, aligning with the interest in controlling vortex states for information storage. We initially obtained zero-field spin configurations by varying ring thickness (t), observing a 360° domain wall in rings with t < 12 nm and bi-vortex wall in rings with t ∼36 nm during magnetization reversal. Notably, an extended stability of the global-vortex state was observed in rings with t > 36 nm, indicating the dominance of global-vortex nucleation in thick asymmetric rings during domain wall movement. We investigate the hysteresis loops and spin configurations by varying the in-plane and out-of-plane anisotropy values. Our findings reveal the presence of multiple vortex cores with different polarities and sense of rotations in the ring for the in-plane anisotropy ∼30 to ∼40 kJ m−3. Additionally, a global-vortex with two vortex cores was formed due to demagnetization energy. We analysed the energy profile of stable magnetization states for various t and anisotropy values. Interestingly, the shape of the hysteresis loop changes significantly for the disc containing different shapes of void. Circular and square-shaped geometries suggest that the bi-vortex state is a stable configuration during magnetization reversal in both cases. The study also indicates the stability of the vortex with a square-shaped void geometry up to a sufficiently large field. For the case of triangular-shaped voids, the global-vortex state was favored with even the small fields. The estimated spin canting angles are found to be correlated with the presence of vortex spin configurations. Overall, these results are important for the development of magnetization vortex-based spintronics devices.
CLASS-OneLoop: accurate and unbiased inference from spectroscopic galaxy surveys
Authors: Linde Dennis , Dizgah Azadeh Moradinezhad , Radermacher Christian , Casas Santiago , Lesgourgues Julien
Published: July 2024

The power spectrum is the most commonly applied summary statistics to extract cosmological information from the observed three-dimensional distribution of galaxies in spectroscopic surveys. We presentCLASS-OneLoop, a new numerical tool, fully integrated into the Boltzmann codeCLASS, enabling the calculation of the one-loop power spectrum of biased tracers in spectroscopic surveys. Built upon the Eulerian moment expansion framework for redshift-space distortions, the implemented model incorporates a complete set of nonlinear biases, counterterms, and stochastic contributions, and includes the infrared resummation and the Alcock-Paczynski effect. The code features an evaluation of the loops by either direct numerical integration or Fast Fourier Transform, and employs a fast-slow parameter decomposition, which is essential for accelerating MCMC runs. After presenting performance and validation tests, as an illustration of the capabilities of the code, we apply it to fit the measured redshift-space halo power spectrum wedges on a ΛCDM subset of theAbacusSummitsimulation suite and considering scales up to kmax= 0.3h/Mpc. We find that the one-loop model adeptly recovers the fiducial cosmology of the simulation, while a simplified model commonly used in the literature for sensitivity forecasts yields significantly biased results. Furthermore, we conduct Monte Carlo Markov Chain (MCMC) forecasts for a DESI-like survey, considering a model with a dynamical dark energy component. Our results demonstrate the ability to independently constrain cosmological and nuisance parameters, even in the presence of a large parameter space with twenty-nine variables.
The anomaly of the CMB power with the latest Planck data
Authors: Billi M. , Barreiro R.B. , Martínez-González E.
Published: July 2024

The lack of power anomaly is an unexpected feature observed at large angular scales in the maps of Cosmic Microwave Background (CMB) produced by the COBE, WMAP and Planck satellites. This signature, which consists in a missing of power with respect to that predicted by the ΛCDM model, might hint at a new cosmological phase before the standard inflationary era.
The main point of this paper is taking into account the latest Planck polarisation data to investigate how the CMB polarisation improves the understanding of this feature. With this aim, we apply to the latest Planck data, both PR3 (2018) and PR4 (2020) releases, a new class of estimators capable of evaluating this anomaly by considering temperature and polarisation data both separately and in a jointly way. This is the first time that the PR4 dataset has been used to study this anomaly. To critically evaluate this feature, taking into account the residuals of known systematic effects present in the Planck datasets, we analyse the cleaned CMB maps using different combinations of sky masks, harmonic range and binning on the CMB multipoles.
Our analysis shows that the estimator based only on temperature data confirms the presence of a lack of power with a lower-tail-probability (LTP), depending on the component separation method, ≤ 0.33% and ≤ 1.76% for PR3 and PR4, respectively. To our knowledge, the LTP≤ 0.33% for the PR3 dataset is the lowest one present in the literature obtained from Planck 2018 data, considering the Planck confidence mask. We find significant differences between these two datasets when polarisation is taken into account most likely due to a different level of systematics. Especially, the analysis with PR3 data, unlike that with PR4, seems to point towards a lack of power at large scales also for polarisation.
Moreover, we also show that for the PR3 dataset the inclusion of the subdominant polarisation information provides estimates that are less likely accepted in a ΛCDM cosmological model than the only-temperature analysis over the entire harmonic-range considered. In particular, at ℓmax = 26, we found that no simulation has a value as low as the data for all the pipelines.
Reparametrization invariant action for gravity with dynamical determinant of metric
Authors: Klusoň J.
Published: July 2024

We present manifestly reparametrization invariant action for theory of gravity
with dynamical determinant of metric. We show that it is similar to a reparametrization invariant action for unimodular gravity. We determine canonical
form of the action and study structure of constraints.
Cluster dynamics modeling of hydrogen retention and desorption in tungsten with saturation and multi-trapping effect of sinks
Authors: Chen Xiaoru , Zhang Yuanyuan , Wei Liuming , Zheng Qirong , Zhang Chuanguo , Li Yonggang
Published: July 2024

Hydrogen (H) retention and desorption in tungsten (W)-based plasma-facing materials are still not well understood, largely due to the limitations of ex-situ observations in experimental detection methods like thermal desorption spectroscopy (TDS). In order to reveal the fundamental mechanisms behind H retention and desorption, we developed a cluster dynamics model, IRadMat-TDS, for theoretical modeling of depth distribution and TDS of deuterium (D) in polycrystalline W. The model newly includes the saturated absorption and emission of D in inherent sinks like grain boundaries (GBs), as well as the multi-trapping effect of D in various types of GBs with different trapping energies. The simulated TDS spectra are in agreement with experimental ones. For polycrystalline W under D ion irradiation within keV-energy range, two typical thermal desorption peaks in TDS at around 490 and 550 K are explicitly attributed to D emission from GBs and vacancies, respectively. And GBs play a major role in D retention. Moreover, the broad peaks in TDS come from the convolution of multi-trapping of D in sinks with different types of trapping sites rather than a single-site approximation.
Structural design of the acrylic vessel for the Jinping Neutrino Experiment
Authors: Wang Zongyi , Liu Yuhao , Chen Shaomin , Wang Yuanqing , Wang Zhe , Huang Ming
Published: July 2024

The Jinping neutrino experiment is designed to have multiple
purposes in the China Jinping Underground Laboratory. Following the
acrylic vessel design requirements proposal, a structural scheme has
been developed and optimized. Subsequently, the stability of the
acrylic shell structure is calculated using finite element
analysis, as well as the load-bearing capacities under various
working conditions. Further, the effects of temperature changes,
rope failures, and Young's modulus of the ropes on the static
behavior of the structure are analyzed. The results indicated that
the stress level and structural displacement of the structure scheme
satisfy the design requirements, as well as the stability of the
vessel under compression. The acrylic vessel is safe in the given
working conditions. Temperature is not a controlling factor in
structural design. The structural scheme ensures basic safety if one
vertical rope, two vertical ropes, or one horizontal rope fails.
Development of indigenous pulse-shape discrimination algorithm for organic scintillation detectors
Authors: Karmakar Annesha , Anil Kumar G. , Bhavika  , Anand V. , Pal Anikesh
Published: July 2024

In this study, we present the development of an indigenous
pulse shape discrimination (PSD) algorithm grounded in tail area and
total area analysis, effectively obviating the necessity for
specialized programmable hardware. Pulse data was collected
utilizing a BC501 detector paired with a Pu-Be source and digitized
in oscilloscope mode during experiments conducted at IIT-Kanpur. The
algorithm developed in this work encompasses essential functions
such as pulse normalization, shaping, peak identification and
removal, and threshold determination. Notably, the algorithm offers
the capability to derive neutron and γ-ray counts, generate
scatter plots, and calculate the figure-of-Merit (FoM). It is
essential to emphasize that the development of this indigenous
Tail-to-Total Area (TtoT) PSD algorithm was a direct response to the
unavailability of dedicated hardware for PSD in the experiment
conducted at IIT-Kanpur. The introduction of the TtoT algorithm
played a pivotal role in enabling offline PSD analysis at
IIT-Kanpur, effectively overcoming infrastructure limitations.
Importantly, the efficacy of our proposed algorithm was tested by
applying it to pulse data from a distinct source-detector
arrangement featuring a BC501A detector and an Cf-252 source. This
comparative analysis also included the Charge Integration (CI)
method and was conducted at IIT-Roorkee. The results obtained from
our algorithm and the CI method exhibited a strong concurrence
concerning the identification of neutrons and γ-rays, along
with FoM metrics.
Asynchrony of the seasonal dynamics of gross primary production and ecosystem respiration
Authors: Yang Linqing , Noormets Asko
Published: July 2024

The phenological cycles of terrestrial ecosystems have shifted with the changing climate, and the altered timings of biogeochemical fluxes may also exert feedback on the climate system. As regulators of land carbon balance, relative shifts in photosynthetic and respiratory phenology under climate change are of great importance. However, the relative seasonal dynamics of these individual processes and their sensitivity to climate factors as well as the implications for carbon cycling are not well understood. In this study, we examined the relationship in the seasonality of gross primary production (GPP) and ecosystem respiration (RE) as well as their temperature sensitivities and the implications for carbon uptake with around 1500 site-years’ of data from FLUXNET 2015 and Boreal Ecosystem Productivity Simulator (BEPS) at 212 sites. The results showed that RE started earlier in the spring and ended later in the autumn than GPP over most biomes. Furthermore, the flux phenology metrics responded differently to temperature: GPP phenology was more sensitive to changes during the spring temperature than RE phenology, and less sensitive to autumn temperature than RE. We found large BEPS-observation discrepancies in seasonality metrics and their apparent temperature sensitivity. The site-based BEPS projections did not capture the observed seasonal metrics and temperature sensitivities in either GPP or RE seasonality metrics. Improved understanding of the asynchrony of GPP and RE as well as different sensitivity of environmental factors are of great significance for reliable future carbon balance projections.
Assessing the nonlinearity of wintertime PM2.5 formation in response to precursor emission changes in North China with the adjoint method
Authors: Lu Ni , Zhang Lin , Wang Xiaolin , Liu Zehui , Li Danyang , Xu Jiayu , Tan Haiyue , Zhou Mi , Henze Daven K
Published: July 2024

While China’s clean air actions implemented since 2013 have been effective in mitigating PM2.5 air pollution, the large emission reductions during the COVID-19 lockdown period in early 2020 did not similarly alleviate PM2.5 pollution in North China, reflecting a distinct nonlinear chemical response of PM2.5 formation to emission changes. Here we apply emission-concentration relationships for PM2.5 diagnosed using the adjoint approach to quantitatively assess how chemical nonlinearity affects PM2.5 over Beijing in February 2020 in response to two emission reduction scenarios: the COVID-19 lockdown and 2013–2017 emission controls. We find that, in the absence of chemical nonlinearity, the COVID-19 lockdown would decrease PM2.5 in Beijing by 17.9 μg m–3, and the 2013–2017 emission controls resulted in a larger decrease of 54.2 μg m–3 because of greater reductions of SO2 and primary aerosol emissions. Chemical nonlinearity offset the decrease for Beijing PM2.5 by 3.4 μg m–3 during the lockdown due to enhanced sensitivity of aerosol nitrate to NO
x
emissions, but enhanced the efficiency of 2013–2017 emission controls by 11.9 μg m–3 due to the weakened heterogeneous reaction of sulfate. Such nonlinear chemical effects are important to estimate and consider when designing or assessing air pollution control strategies.