bluuebunny/crossref_metadata_2025 huggingface dataset:
Wind turbines fault diagnosis method under variable working conditions based on AMVMD and deep discrimination transfer learning network
Authors: Shi Peiming , Jia Linjie , Yi Siying , Han Dongying
Published: January 2024

With the wide application of wind turbines, the bearing fault diagnosis of wind turbines has become a research hotspot. Under complex variable working conditions, the vibration signals of bearing components show non-stationary characteristics. Therefore, it is challenging to extract fault features using typical fault diagnosis methods. This paper proposes Adaptive Multivariate Variational Mode Decomposition combined with an improved Deep Discrimination Transfer Learning Network (AMVMD-IDDTLN) for bearing fault diagnosis of wind turbines under variable working conditions. First, the AMVMD method is used for the adaptive decomposition of the original signal, and use SE-ResNet18 convolutional neural network to obtain the transfer features of the source domain and target domain. Then, marginal distribution differences and conditional differences are assessed by DDM measures. The whole model is optimized by cross-entropy and improved joint distribution adaptation loss function, and the identification and classification of cross-working fault characteristics of the wind turbine- bearings are realized. The model achieves 99.48% transfer learning for the ten classifications of CWRU data set, 97% transfer learning for the four classifications of UPB data set, and 90% transfer learning for wind turbine bearing data across working conditions and across equipment. It is concluded that: Compared with similar models, the AMVMD-IDDTLN model proposed in this paper has higher diagnostic accuracy and faster convergence rate, which has certain practicality.
An optimized sparse deep belief network with momentum factor for fault diagnosis of radar transceivers
Authors: Shi Jiantao , Li Xianfeng , Chen Chuang
Published: January 2024

Transceiver is a crucial component of radar system that allows for the regulation of signal phase and amplitude as well as the amplification of both transmitted and received signals. Its operational efficiency has a significant impact on the whole dependability of the radar system. To ensure the safe and reliable operation of the radar system, an optimized sparse deep belief network with momentum factor is developed to diagnose potential faults of radar transceivers. Firstly, a momentum term is added into the parameter update to enhance the anti-oscillation ability of model parameters in training, while a sparse regular term is integrated into the deep belief network to prevent the model from overfitting. Secondly, to automatically configure the model hyper-parameters, a hybrid sine cosine algorithm (HSCA) with dynamic inertia weight and adaptive strategies is proposed. Thus, an effective diagnostic model named HSCA-MS-DBN is formed by combining sparse deep belief network with momentum factor and HSCA. The efficiency of the proposed HSCA-MS-DBN model is confirmed using an actual-world radar transceiver dataset, and the findings from experiments reveal that this model surpasses multiple prominent intelligent models.
Small Darcy number limit of the Navier–Stokes–Darcy system
Authors: Lyu Wenqi , Wang Xiaoming
Published: January 2024

We study the small Darcy number behavior of the Navier–Stokes–Darcy system with the conservation of mass, Beavers–Joseph–Saffman–Jones condition, and the Lions balance of the normal-force interface boundary conditions imposed on the interface separating the Navier–Stokes flow and Darcy flow. We show that the asymptotic behavior of the coupled system, at small Darcy number, can be captured by two semi-decoupled Darcy number independent sequences: a sequence of (linearized) Navier–Stokes equations, and a sequence of Darcy equations with appropriate initial and boundary data. Approximate solutions to any order of the small parameter (Darcy number) can be constructed via the two sequences. The local in time validity of the asymptotic expansion up to second order is presented. And the global in time convergence is derived under the assumption that the Reynolds number is below a threshold value.
Dynamics of the Fermi–Ulam model in an external gravitational field
Authors: Liang Yaqi , Li Xiong
Published: January 2024

In this paper, we are concerned with the possibility of bounded growth of the energy of the Fermi–Ulam model in an external gravitational field. The boundedness of all orbits is established when the forced oscillation is almost periodic and real analytic with respect to time. Furthermore, the existence of infinitely many bounded orbits will be proved when the forced oscillation is only supposed to be bounded in the C
2 norm with no other assumptions, and a specifically forced oscillation is constructed such that an unbounded orbit appears.
Kolmogorov’s dissipation number and determining wavenumber for dyadic models
Authors: Dai Mimi , Hoeller Margaret , Peng Qirui , Zhang Xiangxiong
Published: January 2024

We study some dyadic models for incompressible magnetohydrodynamics and Navier–Stokes equation. The existence of fixed point and stability of the fixed point are established. The scaling law of Kolmogorov’s dissipation wavenumber arises from heuristic analysis. In addition, a time-dependent determining wavenumber is shown to exist; moreover, the time average of the determining wavenumber is proved to be bounded above by Kolmogorov’s dissipation wavenumber. Additionally, based on the knowledge of the fixed point and stability of the fixed point, numerical simulations are performed to illustrate the energy spectrum in the inertial range below Kolmogorov’s dissipation wavenumber.
Time-of-flight scatter rejection in x-ray radiography
Authors: Rossignol J , Bélanger G , Gaudreault D , Therrien A C , Bérubé-Lauziére Y , Fontaine R
Published: January 2024

Objective. Time-of-flight (TOF) scatter rejection allows for identifying and discarding scattered photons without the use of an anti-scatter grid (ASG). Although TOF scatter rejection was initially presented for cone-beam computed tomography, we propose, herein, to extend this approach to x-ray radiography. This work aims to evaluate with simulations if TOF scatter rejection can outperform ASGs for radiography. Approach. GATE was used to simulate the radiography of a head and a torso and a water cylinder with bone inserts in a system with total timing jitters from 0 ps up to 500 ps full-width-at-half-maximum. The transmission factor of TOF scatter rejection for primary and scattered photons was evaluated as if it were a virtual ASG. Main results. With a total timing jitter of 50 ps, TOF scatter rejection can reach a selectivity of 4.93 with a primary photons transmission of 99%. Reducing the timing jitter close to 0 ps increases the selectivity up to 15.85 for a head and torso radiography, outperforming typical ASGs which usually have a selectivity from 2.5 to 10 with a primary photons transmission from 50% to 70%. Significance. This suggests that TOF scatter rejection may be suitable to replace ASGs in applications requiring lower radiation exposure if sufficiently low timing jitter is achieved.
Effects of cellular radioresponse on therapeutic helium-, carbon-, oxygen-, and neon-ion beams: a simulation study
Authors: Masuda Takamitsu , Inaniwa Taku
Published: January 2024

Objective. Helium, oxygen, and neon ions in addition to carbon ions will be used for hypofractionated multi-ion therapy to maximize the therapeutic effectiveness of charged-particle therapy. To use new ions in cancer treatments based on the dose-fractionation protocols established in carbon-ion therapy, this study examined the cell-line-specific radioresponse to therapeutic helium-, oxygen-, and neon-ion beams within wide dose ranges. Approach. Response of cells to ions was described by the stochastic microdosimetric kinetic model. First, simulations were made for the irradiation of one-field spread-out Bragg peak beams in water with helium, carbon, oxygen, and neon ions to achieve uniform survival fractions at 37%, 10%, and 1% for human salivary gland tumor (HSG) cells, the reference cell line for the Japanese relative biological effectiveness weighted dose system, within the target region defined at depths from 90 to 150 mm. The HSG cells were then replaced by other cell lines with different radioresponses to evaluate differences in the biological dose distributions of each ion beam with respect to those of carbon-ion beams. Main results. For oxygen- and neon-ion beams, the biological dose distributions within the target region were almost equivalent to those of carbon-ion beams, differing by less than 5% in most cases. In contrast, for helium-ion beams, the biological dose distributions within the target region were largely different from those of carbon-ion beams, more than 10% in several cases. Significance. From the standpoint of tumor control evaluated by the clonogenic cell survival, this study suggests that the dose-fractionation protocols established in carbon-ion therapy could be reasonably applied to oxygen- and neon-ion beams while some modifications in dose prescription would be needed when the protocols are applied to helium-ion beams. This study bridges the gap between carbon-ion therapy and hypofractionated multi-ion therapy.
Balanced transformer: efficient classification of glioblastoma and primary central nervous system lymphoma
Authors: Wang Shigang , Wu Jinyang , Chen Meimei , Huang Sa , Huang Qian
Published: January 2024

Objective. Primary central nervous system lymphoma (PCNSL) and glioblastoma (GBM) are malignant primary brain tumors with different biological characteristics. Great differences exist between the treatment strategies of PCNSL and GBM. Thus, accurately distinguishing between PCNSL and GBM before surgery is very important for guiding neurosurgery. At present, the spinal fluid of patients is commonly extracted to find tumor markers for diagnosis. However, this method not only causes secondary injury to patients, but also easily delays treatment. Although diagnosis using radiology images is non-invasive, the morphological features and texture features of the two in magnetic resonance imaging (MRI) are quite similar, making distinction with human eyes and image diagnosis very difficult. In order to solve the problem of insufficient number of samples and sample imbalance, we used data augmentation and balanced sample sampling methods. Conventional Transformer networks use patch segmentation operations to divide images into small patches, but the lack of communication between patches leads to unbalanced data layers. Approach. To address this problem, we propose a balanced patch embedding approach that extracts high-level semantic information by reducing the feature dimensionality and maintaining the geometric variation invariance of the features. This approach balances the interactions between the information and improves the representativeness of the data. To further address the imbalance problem, the balanced patch partition method is proposed to increase the receptive field by sampling the four corners of the sliding window and introducing a linear encoding component without increasing the computational effort, and designed a new balanced loss function. Main results. Benefiting from the overall balance design, we conducted an experiment using Balanced Transformer and obtained an accuracy of 99.89%, sensitivity of 99.74%, specificity of 99.73% and AUC of 99.19%, which is far higher than the previous results (accuracy of 89.6% ∼ 96.8%, sensitivity of 74.3% ∼ 91.3%, specificity of 88.9% ∼ 96.02% and AUC of 87.8% ∼ 94.9%). Significance. This study can accurately distinguish PCNSL and GBM before surgery. Because GBM is a common type of malignant tumor, the 1% improvement in accuracy has saved many patients and reduced treatment times considerably. Thus, it can provide doctors with a good basis for auxiliary diagnosis.
Precision assessment of bowel motion quantification using 3D cine-MRI for radiotherapy
Authors: Barten D L J , van Kesteren Z , Laan J J , Dassen M G , Westerveld G H , Pieters B R , de Jonge C S , Stoker J , Bel A
Published: January 2024

Objective. The bowel is an important organ at risk for toxicity during pelvic and abdominal radiotherapy. Identifying regions of high and low bowel motion with MRI during radiotherapy may help to understand the development of bowel toxicity, but the acquisition time of MRI is rather long. The aim of this study is to retrospectively evaluate the precision of bowel motion quantification and to estimate the minimum MRI acquisition time. Approach. We included 22 gynaecologic cancer patients receiving definitive radiotherapy with curative intent. The 10 min pre-treatment 3D cine-MRI scan consisted of 160 dynamics with an acquisition time of 3.7 s per volume. Deformable registration of consecutive images generated 159 deformation vector fields (DVFs). We defined two motion metrics, the 50th percentile vector lengths (VL50) of the complete set of DVFs was used to measure median bowel motion. The 95th percentile vector lengths (VL95) was used to quantify high motion of the bowel. The precision of these metrics was assessed by calculating their variation (interquartile range) in three different time frames, defined as subsets of 40, 80, and 120 consecutive images, corresponding to acquisition times of 2.5, 5.0, and 7.5 min, respectively. Main results. For the full 10 min scan, the minimum motion per frame of 50% of the bowel volume (M50%) ranged from 0.6–3.5 mm for the VL50 motion metric and 2.3–9.0 mm for the VL95 motion metric, across all patients. At 7.5 min scan time, the variation in M50% was less than 0.5 mm in 100% (VL50) and 95% (VL95) of the subsets. A scan time of 5.0 and 2.5 min achieved a variation within 0.5 mm in 95.2%/81% and 85.7%/57.1% of the subsets, respectively. Significance. Our 3D cine-MRI technique quantifies bowel loop motion with 95%–100% confidence with a precision of 0.5 mm variation or less, using a 7.5 min scan time.
Frequency-dependent electron power absorption mode transitions in capacitively coupled argon-oxygen plasmas
Authors: Derzsi A , Vass M , Masheyeva R , Horváth B , Donkó Z , Hartmann P
Published: January 2024

Phase Resolved Optical Emission Spectroscopy (PROES) measurements combined with 1d3v Particle-in-Cell/Monte Carlo Collisions simulations are performed to investigate the excitation dynamics in low-pressure capacitively coupled plasmas (CCPs) in argon-oxygen mixtures. The system used for this study is a geometrically symmetric CCP reactor operated in a 70% Ar-30% O2 mixture at 120 Pa, applying a peak-to-peak voltage of 350 V, with a wide range of driving RF frequencies (2 MHz 

⩽
f
⩽

15 MHz). The measured and calculated spatio-temporal distributions of the electron impact excitation rates from the Ar ground state to the Ar

2

p
1

level show good qualitative agreement. The distributions show significant frequency dependence, which is generally considered to be predictive of transitions in the dominant discharge operating mode. Three frequency ranges can be distinguished, showing distinctly different excitation characteristics: (i) in the low frequency range (

f
⩽

3 MHz), excitation is strong at the sheaths and weak in the bulk region; (ii) at intermediate frequencies (3.5 MHz

⩽
f
⩽

5 MHz), the excitation rate in the bulk region is enhanced and shows striation formation; (iii) above 6 MHz, excitation in the bulk gradually decreases with increasing frequency. Boltzmann term analysis was performed to quantify the frequency-dependent contributions of the Ohmic and ambipolar terms to the electron power absorption.
Dynamics of spin relaxation in nonequilibrium magnetic nanojunctions
Authors: Smorka Rudolf , Thoss Michael , Žonda Martin
Published: January 2024

We investigate nonequilibrium phenomena in magnetic nano-junctions using a numerical approach that combines classical spin dynamics with the hierarchical equations of motion technique for quantum dynamics of conduction electrons. Our focus lies on the spin dynamics, where we observe non-monotonic behavior in the spin relaxation rates as a function of the coupling strength between the localized spin and conduction electrons. Notably, we identify a distinct maximum at intermediate coupling strength, which we attribute to a competition that involves the increasing influence of the coupling between the classical spin and electrons, as well as the influence of decreasing local density of states at the Fermi level. Furthermore, we demonstrate that the spin dynamics of a large open system can be accurately simulated by a short chain coupled to semi-infinite metallic leads. In the case of a magnetic junction subjected to an external DC voltage, we observe resonant features in the spin relaxation, reflecting the electronic spectrum of the system. The precession of classical spin gives rise to additional side energies in the electronic spectrum, which in turn leads to a broadened range of enhanced damping in the voltage.
Necessary conditions for convex-periodic, elliptic-periodic, inclined-periodic, and rogue wave-solutions to exist for the multi-dispersions Schrodinger equation
Authors: Alquran Marwan
Published: January 2024

In this study, we revisit the modified Schrödinger equation, which incorporates multiple dispersion terms, including linear, nonlinear, and random dispersion. We establish the essential constraints on the model’s parameters to ensure the presence of complex-valued solutions. Subsequently, we employ effective and explicit techniques such as the extended tanh-coth expansion, rational sine-cosine functions, and rational sinh-cosh functions to derive innovative types of periodic solutions for the proposed model. These solutions demonstrate unique physical properties applicable to various complex media, such as surface water waves, optical fiber pulses, and plasma waves.
Developing computationally efficient optimal control strategies to eradicate Rubella disease
Authors: Ahmad W , Butt A I K , Akhtar N , Rafiq M , Gohar M , Idrees Z , Ahmad N
Published: January 2024

The threat of Rubella virus disease looms large, posing significant risks to public health and emphasizing the urgent need for comprehensive prevention, control, and awareness strategies. We conducted an extensive analysis of a newly developed SEITR deterministic model for the lethal Rubella virus disease. The main objective of our study is to gain deep insights into the disease dynamics and devise an optimal control strategy for the model, utilizing vaccination and treatment as preventive measures. We employed various mathematical techniques to establish the positivity and bounded nature of solutions. The value of threshold parameter is computed using the next-generation method to anticipate future dynamical behavior of the epidemic. The local and global stability of the equilibrium points was successfully assessed. Additionally, we utilized the well-known Non-Standard Finite Difference (NSFD) method to obtain numerical solutions for the Rubella model. A numerical analysis is carried out to assess the efficacy of a constant treatment strategy, and the results are presented through graphical illustrations. The developed model is subjected to sensitivity analysis and the most sensitive parameters are identified. In addition, the bifurcation nature of the model is examined. Subsequently, an optimal control problem is introduced for the model, aiming to determine the best time-dependent strategies for treatment and vaccination. The main goal is to reduce the number of individuals infected within the human population and the cost of controls. Designed optimal control problem and its corresponding optimality conditions of Pontryagin type have been derived. An important aspect of this study is the utilization of the NSFD method, implemented backward in time, to solve the optimal control problem, as opposed to other conventional methods. Numerical simulations were carried out to assess the impact of the applied controls on the dynamics of all classes, both before and after optimization.
A CV weighted method for oil-water two-phase flow of non-contact multi-frequency el7ectrical impedance tomography
Authors: Bai Meng , Wang Xiaoxin
Published: January 2024

Electrical tomography (ET) technology has attracted extensive attention in the field of scientific research on oil–water two-phase flow due to its advantages of non-intrusion, non-radiation, and simple equipment structure. Affected by Maxwell–Wagner-Sillars (MWS) effect, more imaging information can be obtained by changing the excitation frequency, especially for the mixtures with conductive phases. In this paper, a CV (coefficient of variation )-weighted method of non-contact multi-frequency electrical impedance tomography (NM-EIT) system is carried out for water-oil two-phase flow imaging. Firstly, the frequency response of the measurement system is studied and the electrical impedance information of medium in the region of interest (RoI) is observed. Secondly, the measured electrical impedance information with with different excitation frequencies are weighted by CV method. Finally, combined with the classic image reconstruction algorithm, the simulation and static experiment are carried out to verify the reconstruction effect of the proposed method. The imaging accuracies under different frequencies and flow patterns are analyzed, and a measurement experimental platform is set up to verify the reconstruction effect of the proposed method. The experimental results show that the CV-based multi-frequency weighted method maintains a higher imaging accuracy than single-frequency imaging.
Taming redshift-space distortion effects in the EFTofLSS and its application to data
Authors: D'Amico Guido , Senatore Leonardo , Zhang Pierre , Nishimichi Takahiro
Published: January 2024

Former analyses of the BOSS data using the Effective Field Theory of Large-Scale Structure (EFTofLSS) have measured that the largest counterterms are the redshift-space distortion ones. This allows us to adjust the power-counting rules of the theory, and to explicitly identify that the leading next-order terms have a specific dependence on the cosine of the angle between the line-of-sight and the wavenumber of the observable, μ. Such a specific μ-dependence allows us to construct a linear combination of the data multipoles, P̸, where these contributions are effectively projected out, so that EFTofLSS predictions for P̸ have a much smaller theoretical error and so a much higher k-reach. The remaining data are organized in wedges in μ space, have a μ-dependent k-reach because they are not equally affected by the leading next-order contributions, and therefore can have a higher k-reach than the multipoles. Furthermore, by explicitly including the highest next-order terms, we define a `one-loop+' procedure, where the wedges have even higher k-reach. We study the effectiveness of these two procedures on several sets of simulations and on the BOSS data. The resulting analysis has identical computational cost as the multipole-based one, but leads to an improvement on the determination of some of the cosmological parameters that ranges from 10% to 100%, depending on the survey properties.
Eternal inflation and collapse theories
Authors: Lechuga R.L. , Sudarsky D.
Published: January 2024

The eternal inflation problem continues to be considered one of standard's cosmology most serious shortcomings. This arises when one considers the effects of “quantum fluctuations” on the zero mode of inflaton field during a Hubble time in the inflationary epoch.
In the slow-roll regime it is quite clear that such quantum fluctuations could dwarf the classical rolling down of the inflaton, and with overwhelming probability this prevents inflation from ever ending. When one recognizes that quantum fluctuations can not be taken as synonymous of stochastic fluctuations, but rather intrinsic levels of indefiniteness in the quantities in question, one concludes that the eternal inflation problem simply does not exist. However, the same argument would serve to invalidate the account for the generation of the primordial seeds of cosmic structure as has been amply discussed elsewhere [1,2,3]. In order to do address that issue, one must explain the breaking of homogeneity and isotropy of the situation prevailing during the early inflationary epoch (at both the quantum and classical levels of the description). For that one needs to rely on some additional element, beyond those present in the traditional treatments. The so called spontaneous collapse theories offer a viable candidate for that element, namely the stochastic and spontaneous state reduction characteristic of those proposals possesses the basic features to break those symmetries. In fact, a version of the CSL theory adapted to the cosmological context has been shown to offer a satisfactory account for the origin the seeds of cosmic structure with an adequate power spectrum [2], and will serve as the basis of our analysis. However, once such stochastic collapse is introduced into the theoretical framework the eternal inflation problem has the potential reappear.
In this manuscript we explore those issues in detail and discuss an avenue that seems to allow for a satisfactory account for the generation of the primordial inhomogeneities and anisotropies while freeing the theory from the eternal inflation problem.
Minkowski Functionals in 𝖲𝖮(3) for the spin-2 CMB polarisation field
Authors: Carrón Duque J. , Carones A. , Marinucci D. , Migliaccio M. , Vittorio N.
Published: January 2024

The study of the angular power spectrum of Cosmic Microwave Background (CMB) anisotropies, both in intensity and in polarisation, has led to the tightest constraints on cosmological parameters. However, this statistical quantity is not sensitive to any deviation from Gaussianity and statistical isotropy in the CMB data. Minkowski Functionals (MFs) have been adopted as one of the most powerful statistical tools to study such deviations, since they characterise the topology and geometry of the field of interest.
In this paper, we extend the application of MFs to CMB polarisation data by introducing a new formalism, where we lift the spin 2 polarisation field to a scalar function in a higher-dimensional manifold: the group of rotations of the sphere, SO(3). Such a function is defined as f = Q cos(2ζ) - U sin(2ζ). We analytically obtain the expected values for the MFs of f in the case of Gaussian isotropic polarisation maps. Furthermore, we present a new pipeline which estimates these MFs from input HEALPix polarisation maps. We apply it to CMB simulations in order to validate the theoretical results and the methodology.
The pipeline is to be included in the publicly available Python package
Pynkowski
.
Refractive neutrino masses, ultralight dark matter and cosmology
Authors: Sen Manibrata , Smirnov Alexei Y.
Published: January 2024

We consider in detail a possibility that the observed neutrino oscillations are due to refraction on ultralight scalar boson dark matter.
We introduce the refractive mass squared, m̃2, and study its properties: dependence on neutrino energy,
state of the background, etc. If the background is in a state of cold gas of particles, m̃2 shows a resonance dependence on energy. Above the resonance (E ≫ ER
), we find that m̃2 has the same properties as usual vacuum mass squared.
Below the resonance, m̃2 decreases with energy, which (if realised) allows to avoid the cosmological bound on the sum of neutrino masses. Also, m̃2 may depend on time. We consider the validity of the results: effects of multiple interactions with scalars, and modification of the dispersion relation. We show that for values of parameters of the system required to
reproduce the observed neutrino masses, perturbativity is broken at low energies, which border above the resonance.
If the background is in the state of coherent classical field, the refractive mass does not depend on energy explicitly but may show
time dependence. It coincides with the refractive mass in a cold gas at high energies.
Refractive nature of neutrino mass can be tested by searches of its dependence on energy and time.
12 × 2 pt combined probes: pipeline, neutrino mass, and data compression
Authors: Reeves Alexander , Nicola Andrina , Refregier Alexandre , Kacprzak Tomasz , Valle Luis Fernando Machado Poletti
Published: January 2024

With the rapid advance of wide-field surveys it is increasingly important to perform combined cosmological probe analyses. We present a new pipeline for simulation-based multi-probe analyses, which combines tomographic large-scale structure (LSS) probes (weak lensing and galaxy clustering) with cosmic microwave background (CMB) primary and lensing data. These are combined at the C
ℓ-level, yielding 12 distinct auto- and cross-correlations. The pipeline is based on UFalconv2, a framework to generate fast, self-consistent map-level realizations of cosmological probes from input lightcones, which is applied to the CosmoGridV1 N-body simulation suite. It includes a non-Gaussian simulation-based covariance for the LSS tracers, several data compression schemes, and a neural network emulator for accelerated theoretical predictions. We validate the pipeline by comparing the simulations to these predictions, and our derived constraints to earlier analyses. We apply our framework to a simulated 12×2 pt tomographic analysis of KiDS, BOSS, and Planck, and forecast constraints for a ΛCDM model with a variable neutrino mass. We find that, while the neutrino mass constraints are driven by the CMB data, the addition of LSS data helps to break degeneracies and improves the constraint by up to 35%. For a fiducial Mν
 = 0.15 eV, a full combination of the above CMB+LSS data would enable a 3σ constraint on the neutrino mass. We explore data compression schemes and find that MOPED outperforms PCA and is made robust using the derivatives afforded by our automatically differentiable emulator. We also study the impact of an internal lensing tension in the CMB data, parametrized by AL
, on the neutrino mass constraint, finding that the addition of LSS to CMB data including all cross-correlations is able to mitigate the impact of this systematic. UFalconv2 and a MOPED compressed Planck CMB primary + CMB lensing likelihood are made publicly available.[UFalconv2: https://cosmology.ethz.ch/research/software-lab/UFalcon.html, compressed Planck CMB primary + CMB lensing likelihood: https://github.com/alexreevesy/planck_compressed.]
Elastic scattering of cosmological gravitational wave backgrounds: primordial black holes and stellar objects
Authors: Howard Marcell , König Morgane
Published: January 2024

Primordial black holes (PBHs) are plausible dark matter candidates that formed from the gravitational collapse of primordial density fluctuations. Current observational constraints allow asteroid-mass PBHs to account for all of the cosmological dark matter. We show that elastic scattering of a cosmological gravitational wave background, these black holes generate spectral distortions on the background of 0.3% for cosmologically relevant frequencies without considering coherent scattering and 5% when the coherent enhancement is included. Scattering from stellar objects induce much smaller distortions. Detectability of this signal depends on our ultimate understanding of the unperturbed background spectrum.
Phase-field simulations of the effect of temperature and interface for zirconium δ-hydrides
Authors: Chen 陈 Zi-Hang 子航 , Sheng 盛 Jie 杰 , Liu 刘 Yu 瑜 , Shi 施 Xiao-Ming 小明 , Huang 黄 Houbing 厚兵 , Xu 许 Ke 可 , Wang 王 Yue-Chao 越超 , Wu 武 Shuai 帅 , Sun 孙 Bo 博 , Liu 刘 Hai-Feng 海风 , Song 宋 Hai-Feng 海峰
Published: January 2024

Hydride precipitation in zirconium cladding materials can damage their integrity and durability. Service temperature and material defects have a significant effect on the dynamic growth of hydrides. In this study, we have developed a phase-field model based on the assumption of elastic behaviour within a specific temperature range (613 K–653 K). This model allows us to study the influence of temperature and interfacial effects on the morphology, stress, and average growth rate of zirconium hydride. The results suggest that changes in temperature and interfacial energy influence the length-to-thickness ratio and average growth rate of the hydride morphology. The ultimate determinant of hydride orientation is the loss of interfacial coherency, primarily induced by interfacial dislocation defects and quantifiable by the mismatch degree q. An escalation in interfacial coherency loss leads to a transition of hydride growth from horizontal to vertical, accompanied by the onset of redirection behaviour. Interestingly, redirection occurs at a critical mismatch level, denoted as q
c, and remains unaffected by variations in temperature and interfacial energy. However, this redirection leads to an increase in the maximum stress, which may influence the direction of hydride crack propagation. This research highlights the importance of interfacial coherency and provides valuable insights into the morphology and growth kinetics of hydrides in zirconium alloys.
Development and evaluation of emulsified reference materials for magnetic resonance imaging
Authors: Lee Sunyoung , Hwangbo Seonae , Hong Cheolpyo , Lee Changwoo , Cho Hyo-Min
Published: January 2024

Hepatic steatosis is characterized by an abnormal accumulation of lipids within hepatocytes. Magnetic resonance imaging (MRI) is a widely used noninvasive method that can accurately and objectively quantify liver fat. To evaluate the accuracy of the quantitatively measured fat fraction, stable and homogenous qualified material is needed as a reference. Surfactant-free micro-emulsions of three fat fractions I, II, and III, corresponding to (9.12 ± 0.02)%, (18.32 ± 0.04)%, and (27.86 ± 0.05)%, respectively, were prepared using a high-intensity focused ultrasonic emulsification technique. The targeted fat fraction of 10%–30% covers the range of grade I moderate non-alcoholic fatty liver disease, which occurs in the early stages that require early detection. Water contents as the main component of the emulsified reference materials (RMs) were determined using the Karl Fisher titration method to evaluate the stability and homogeneity of the RMs. The water contents of fat fraction I, II, and III were (89.12 ± 1.08)%, (79.87 ± 0.81)%, and (72.71 ± 1.29)%, respectively. The RMs were stable for six months and showed good homogeneity with both standard deviations between and within units in the range of 0.3%–0.6%. The physical phantom consisted of nine vials of RMs surrounded by agarose gel. The phantom was scanned on 3 T MRI (Siemens MAGNETOM Vida, Siemens Healthineers, Erlangen, Germany). The correlation between the measured proton density fat fraction values and the fabricated fat fraction values was evaluated using linear regression analysis. The slope of the linear fitting was 0.99, and the intercept was −0.88%. These results show that the developed RMs can provide a reference value for the measured fat fraction from a medical imaging system to evaluate the effectiveness of a measurement procedure. It is also expected that the developed RMs can be utilized to harmonize the measured values across multi-site.
Transfer learning with data alignment and optimal transport for EEG based motor imagery classification
Authors: Chu Chao , Zhu Lei , Huang Aiai , Xu Ping , Ying Nanjiao , Zhang Jianhai
Published: January 2024

Objective. The non-stationarity of electroencephalogram (EEG) signals and the variability among different subjects present significant challenges in current Brain–Computer Interfaces (BCI) research, which requires a time-consuming specific calibration procedure to address. Transfer Learning (TL) offers a potential solution by leveraging data or models from one or more source domains to facilitate learning in the target domain, so as to address these challenges. Approach. In this paper, a novel Multi-source domain Transfer Learning Fusion (MTLF) framework is proposed to address the calibration problem. Firstly, the method transforms the source domain data with the resting state segment data, in order to decrease the differences between the source domain and the target domain. Subsequently, feature extraction is performed using common spatial pattern. Finally, an improved TL classifier is employed to classify the target samples. Notably, this method does not require the label information of target domain samples, while concurrently reducing the calibration workload. Main results. The proposed MTLF is assessed on Datasets 2a and 2b from the BCI Competition IV. Compared with other algorithms, our method performed relatively the best and achieved mean classification accuracy of 73.69% and 70.83% on Datasets 2a and 2b respectively. Significance. Experimental results demonstrate that the MTLF framework effectively reduces the discrepancy between the source and target domains and acquires better classification performance on two motor imagery datasets.
Impact of helium and hydrogen plasma exposure on surface damage and erosion of tungsten
Authors: Sakamoto Ryuichi , Bernard Elodie , Kreter Arkadi , Martin Céline
Published: January 2024

The impact of helium plasma exposure on the tungsten surface damage structure development and erosion has been investigated by comparing the impact of hydrogen plasma exposure. Crystal orientation dependence of the undulating surface structure formation and erosion rate is observed on the plasma-exposed tungsten surface independently from the plasma species. The top surface of the plasma exposed tungsten has a tendency to {100} plane independently from the initial surface orientation. Although hydrogen and/or helium cause no erosion in tungsten under incident ion energy exposure conditions below the sputtering threshold, inevitable minute impurities, like oxygen, play an essential role in erosion, and significant erosion can be observed even at 30 eV.
Brownian fluctuations of kinetic energy under Lorentz force
Authors: Paraguassú Pedro V
Published: January 2024

In stochastic thermodynamics, significant attention has been given to studying the statistical behavior of thermodynamic quantities, such as heat and work. However, fluctuations in other quantities, such as kinetic energy and internal energy, can also exhibit intriguing statistical properties. In this study, we investigate the fluctuations of kinetic energy within an initially equilibrated underdamped Brownian particle subsequently exposed to a Lorentz force, comprising both electric and magnetic fields, and provide insights through the examination of the characteristic function, central moments, and kinetic energy distribution.
A broad class of nonlinear Langevin equations with drift and diffusion coefficients separable in time and space: generalized n-moment, ergodicity, Einstein relation, and fluctuations of the system
Authors: Fa Kwok Sau , Pianegonda Salete
Published: January 2024

An extensive class of nonlinear Langevin equations with drift and diffusion coefficients separable in time and space driven by Gaussian white noise is analyzed in terms of a generalized n-moment. We show that the system may exhibit an ergodic property, a key property in statistical mechanics, for space-time-dependent drift and diffusion coefficients. A generalized Einstein relation is also obtained. We also demonstrate that the first two generalized moments and variances are useful to describe the drift and fluctuations of the system.
Eigenvector dreaming
Authors: Benedetti Marco , Carillo Louis , Marinari Enzo , Mézard Marc
Published: January 2024

Among the performance-enhancing procedures for Hopfield-type networks that implement associative memory, Hebbian unlearning (HU) (or dreaming) strikes for its simplicity and lucid biological interpretation. However, it does not easily lend to a clear analytical understanding. Here, we show how HU can be efficiently described in terms of the evolution of the spectrum and the eigenvectors (EVs) of the coupling matrix. That is, we find that HU barely changes the EVs of the coupling matrix, whereas the benefits of the procedure can be ascribed to an intuitive evolution of the spectrum. We use these ideas to design novel dreaming algorithms that are effective from a computational point of view and are analytically far more transparent than the original scheme.
Manifest modular invariance in the near-critical Ising model
Authors: Berg Marcus
Published: January 2024

Using recent results in mathematics, I point out that free energies and scale-dependent central charges away from criticality can be represented in compact form where modular invariance is manifest. The main example is the near-critical Ising model on a thermal torus, but the methods are not restricted to modular symmetry, and apply to automorphic symmetries more generally. One application is finite-size effects.
Low intensity beam current measurement of the Associated Proton Beam Line at CSNS
Authors: Qiu R Y , Huang W L , Li F , Zeng L , Rehman M A , Liu M Y , Liu Q R , Yang R J , Yang T , Xu Z H , Tan Z X
Published: January 2024

The Associated Proton beam Experiment Platform (APEP) beamline is the first proton irradiation facility to use naturally-stripped protons which come from H-beams interacting with the residual gas in the linac beampipe at CSNS. The stripped beam current, which is in the order of 0.1% of the original H-beam and approximately 10 μA, should be measured precisely to provide the proton number for irradiation experiments. Therefore, a low-intensity beam current measurement system was developed with considerations to eliminate the external interferences. An anti-interference design is adopted in this system with an elaboration of probes, cables and electronic low-noise technology to minimize the impact of environmental noise and interferences. This improves the signal-to-noise ratio and enables a more precise measurement of the microampere level pulsed beam current. The system was installed and tested during the summer maintenance in 2021 and 2022. It shows a good agreement with the measurement of the Faraday cup.
A novel BPM mechanical center calibration method based on laser ranging
Authors: Tang X H , Sui Y F , He J , Du Y Y , Cao J S , Yue J H
Published: January 2024

Determining the mechanical center of the beam position monitor (BPM) has been a difficulty for BPM calibration. To solve this problem, a method of positioning the BPM mechanical center based on laser ranging is proposed. This method uses high-precision antenna support as the core locating datum, and high-precision laser ranging sensor (LRS) as the detection tool. By detecting the distances from the LRSs to the antenna support and the distances from the LRSs to the BPM, the mechanical center of the BPM can be indirectly determined. The theoretical system error of this method is within 20 μm, and the experimental results show that the measurement repeatability is 15 μm, This method has low cost and fast speed, which can be used for large-scale calibration.
A new approach for Canadian Light Source future orbit correction system driven by neural network
Authors: Saadat S , Boland M J
Published: January 2024

The orbit correction system (OCS) of the Canadian Light Source (CLS) comprises of 48 sets of BERGOZ beam position monitors (BPM). Each BPM has the ability to measure the position of the beam in both the X and Y directions and can record data at a rate of 1000 times per second. Inverse Response Matrix (IRM) is utilized to determine the optimal strength of the 48 sets of orbit correctors in both the X and Y directions, in order to ensure that the beam follows its desired path. The suggestion in this study is to replace the singular value decomposition (SVD) function with a neural network algorithm, which will act as the central processing unit of the orbit correction system. The training model’s design includes three hidden layers, and within each layer, there are 96 nodes. The neural network’s outputs for regular operations in CLS exhibit a mean square error (MSE) of 10
−7
. Various difficult scenarios were created to test the OCS at 8.0 mA, using offsets in different sections of the storage ring. However, the new model was able to produce the necessary orbit correctors (OC) signals without any trouble.
Beam test of a harmonic kicker cavity
Authors: Bruker M W , Grames J , Guo J , Musson J , Overstreet S A , Pablo M , Park G T , Plawski T , Poelker M , Rimmer R , Roberts B , Speirs D , Wang H , Wilson C , Zhang S
Published: January 2024

A harmonically resonant kicker cavity designed for beam exchange in a circulator cooler was built and successfully tested at the Upgraded Injector Test Facility (UITF) at Jefferson Lab. This type of cavity is being considered for the injection scheme of the Rapid Cycling Synchrotron at the Electron-Ion Collider, where the spacing of neighboring bunches demands very short kicks. Operating with five transversely deflecting modes simultaneously that resonate at 86.6 MHz and consecutive odd harmonics thereof, the prototype cavity selectively deflects 1 of 11 electron bunches while leaving the others unperturbed. An RF driver was developed to synthesize phase- and amplitude-controlled harmonic signals and combine them to drive the cavity while also separating the modes from a field-probe antenna for RF feedback and dynamic tuning. Beam deflection was measured by sweeping the cavity phase; the deflection waveform agrees with expectations, having sub-nanosecond rise and fall times. No emittance increase is observed. Harmonically resonant cavities like the one described provide a new capability for injection and extraction at circulators and rings.
Microbunching of thermionic cathode rf gun beams in the Advanced Photon Source s-band linac
Authors: Dooling J , Brill A , Lobach I , Lumpkin A , Kuklev N , Sereno N , Sun Y
Published: January 2024

We report on measurements of beams from thermionic cathode (TC) rf guns in the Advanced Photon Source S-Band Linac. These measurements include the macropulse out of both new and existing TC guns as well as the observation of microbunching within the micropulses of these beams. A gun chopper limits the macropulse FWHM duration to the 10-ns range. Our objectives were to analyse the new TC gun and investigate microbunching within a TC-rf-gun-generated beam. Our diagnostics elucidated longitudinal beam structures from the ns to the fs time scales. Coherent transition radiation (CTR) interferometers responding to far-infrared wavelengths were employed after each compression stage to provide the autocorrelations of the sub-ps micropulse durations. The first compression stage is an alpha magnet and the second a chicane. A CCD camera was used to image the beam via optical transition radiation from an Al screen at the end of the linac and also employed to measure coherent optical transition radiation (COTR) in the visible range. The COTR diagnostic observations, implying microbunching on a fs time scale, are presented and compared with a longitudinal space-charge impedance model.
Enhancing spatial resolution in MÖNCH for electron microscopy via deep learning
Authors: Xie X. , Barba Flores L. , Bejar Haro B. , Bergamaschi A. , Fröjdh E. , Müller E. , Paton K.A. , Poghosyan E. , Remlinger C.
Published: January 2024

Hybrid Pixel Detectors (HPDs) are highly suitable in diffraction-based electron microscopy
due to their high frame rates (> 1 kHz), high dynamic range, and good radiation
hardness. However, their use in imaging applications has been limited by their relatively large
pixel size (≥ 55 μm) and high-energy (>80 keV) electrons scattering over
multiple pixels in the sensor layer. To realize the full potential of fast, radiation-hard HPDs
across electron microscopy modalities, we developed deep learning techniques to precisely localize
the impact point of incident electrons in MÖNCH, a charge integrating HPD with
25 μm pixel size. With neural network models trained using labeled data via
simulations and experimental measurements, the best spatial resolution obtained, defined in terms
of the root mean squared error, was 0.60 pixels for 200 keV electrons, a three-fold improvement
over a simple charge centroid method. This article presents the training sample generation, deep
learning model design, training results, and imaging outcomes for a sample containing gold
nanoparticles.