bluuebunny/crossref_metadata_2025 huggingface dataset:
Blade tip clearance measurement method based on blade tip timing without the once per revolution sensor
Authors: Guo Xiaolei , Liu Huoxing , Zhou Zhihong
Published: November 2024

The rotor blade tip clearance (BTC) of an aeroengine is a critical parameter that significantly impacts its performance and safety. Accurately determining dynamic BTC has been a focal point of research in experimental testing. Among the effective measurement methods for dynamic BTC, the laser triangulation method based on blade tip timing (BTT) stands out. However, this method typically relies on an once-per-revolution (OPR) sensor for rotor speed and blade serial number information during measurement, leading to increased installation and maintenance costs as well as additional measurement uncertainties. In response to this challenge, this paper presents two signal processing method that eliminate the need for an OPR sensor. The first method, referred to as ‘none OPR method 1,’ closely follows the measurement principles of the traditional method but employs a skewed dual light probe (SDLP) signal to extract rotational speed information, thus obviating the need for an OPR sensor. The second method, ‘none OPR method 2,’ introduces a novel data processing approach that enables BTC determination without any source of rotor speed information. Both methods utilize dynamic and static BTC matching techniques to identify blade serial numbers and achieve BTC measurement without an OPR sensor on a simulated rotor experimental bench. Comparative analysis with traditional method BTC measurements reveals that, under stable rotor speeds, all methods achieve similar levels of accuracy and repeatability errors within 0.025 mm. However, when dealing with variable speed conditions, the traditional method’s accuracy is significantly affected. None OPR method 1 mitigates the impact of rotor speed changes to some extent, while none OPR method 2 remains unaffected by such changes. Importantly, both none OPR methods demonstrate the capability to measure blade-by- blade tip clearances akin to the traditional method.
A resonance-avoiding modal balancing method for multimodal balancing of high-speed flexible rotors
Authors: Deng Zhenhong , Wu Taihuan , Deng Wangqun , Huang Xin , Wu Dengfeng , Zhang Baoqiang , Luo Huageng
Published: November 2024

Conventional balancing methods for high-speed flexible rotors typically necessitate costly and potentially hazardous balancing tests conducted near their critical speeds. This paper first demonstrates the feasibility of achieving multi-mode balancing using measurements taken below the first critical speed, based on traditional modal balancing methods and rotor modal parameters. However, while theoretically viable, this approach is highly susceptible to measurement noise, complicating its practical implementation. To address this issue, we propose an innovative resonance-avoiding modal balancing (RAMB) method specifically designed for multi-mode balancing. In RAMB, balancing is performed mode by mode in a forward manner, effectively integrating the correction weights of lower modes into the balancing equation. This strategy eliminates the need to operate the rotor at unbalanced critical speeds, enhancing the effectiveness of multi-mode balancing while ensuring measurement safety. The effectiveness of both the conventional method and the RAMB approach is validated through numerical simulations and experimental tests as well. The results show that RAMB significantly enhances the vibration suppression over the entire operating speed range while avoiding resonance measurements and exhibits comparable robustness to noise, confirming the validity and superiority of the proposed balancing method.
HoloLume: point-of-application holographic imaging solution
Authors: Javed Isma , Khalid Ramna , Hassan Muhammad Bilal , Dashtdar Masoomeh , Danailov Miltcho , Zubair Muhammad , Cabrera Humberto , Mehmood Muhammad Qasim
Published: November 2024

Digital holographic imaging has emerged as a label-free, non-invasive, and powerful tool, offering a transformative method for the real-time investigation of morphology, density, and other physical and mechanical features of non-biological and biological samples. The rapid development of these portable, economical imaging systems for clinical/non-clinical setups, especially in remote areas, is of great interest. These systems are early point-of-care applications in diagnosis, research, education, and training. This article reports a general-purpose, fully automated portable imaging tool, ‘HoloLume,’ that offers high-resolution 3D imaging that facilitates the comprehensive understanding and analysis of different media. The proposed microscopic system HoloLume realizes the interferograms generation of samples using common-path optics configuration based on a Fresnel biprism, and its motorized stage precisely scans the whole sample with a step of 3.87 μm for quick identification of the region of interest, which makes sure a time-efficient and robust analysis. The prototype, assembled from off-the-shelf components, costs approximately USD ∼776 and weighs around 3 kg. To validate and verify the performance of the HoloLume microscope, we have conducted experiments on both non-biological and biological samples. Thus, its non-invasive nature, high temporal stability, and economical lightweight prototyping make it an ideal choice for hands-on learning and quantitative analysis, reducing the need for time-consuming sample preparation and conventionally expensive microscopic systems. Furthermore, the adaptability of the proposed imaging tool to remote environments ensures wider accessibility and its easy integration with other imaging modalities enables a compact and cost-effective solution for advanced research and in field measurements.
A novel neural network architecture dedicated for LIBS spectrum analysis with its application to steel pipe classification
Authors: Shentu Lifeng , Peng Di , Xi Jiaqi
Published: November 2024

As a nondestructive rapid composition analysis method, laser-induced breakdown spectroscopy (LIBS) has garnered widespread attention in recent years. However, its application in the steel industry has not achieved an effective breakthrough in its detection accuracy because of the matrix effect. This paper introduces a neural network model for LIBS spectral line analysis, which can automatically construct the features and analyze the correlation between them. Notably, this model has been applied to the steel sample classification of seamless steel pipes with good results.
Investigation on the variations of dynamic characteristics of anchor bolts considering transverse inertia effects under tensile loads
Authors: Sun Bing , Zou Junhui , Peng Chusi , Zhu Cong , Zeng Sheng
Published: November 2024

In the case where tunnel anchor bolts are located in strata with limited surrounding rock boundaries, the response signals of the anchor bolts are affected by the tensile load and the transverse inertia effect, resulting in a decrease in the reliability of the non-destructive testing (NDT) results. To accurately assess the anchorage quality under these disturbances, a vibration energy loss model for anchor bolts after excitation was proposed. NDT experiments and numerical simulation studies were conducted on intact and defective anchor bolts under different conditions, analyzing the variation patterns of structural dynamic characteristics such as the first-order natural frequency, the first-order damping ratio, and the vibration energy loss under the influence of tensile load and transverse inertia effect. The results show that during the gradual increase of the tensile load, the first-order natural frequency first increases and then decreases; the first-order damping ratio exhibits an overall trend of an initial slight decline, followed by an increase, and then a subsequent decrease; and the rate of energy loss initially decreases and then increases. The presence of anchorage defects leads to a reduction in the first-order natural frequency, the first-order damping ratio, and the energy loss of the anchor bolt. As the transverse inertia effect intensifies, the first-order natural frequency initially increases and then decreases, the first-order damping ratio decreases, and the energy loss initially decreases slightly before increasing. The numerical simulation verifies the applicability of the theoretical model and explores the influence of defect location on energy loss. The results indicate that the closer the defect location is to the free end, the less the vibration energy loss of the anchor bolt.
Resistance standards with very small calculable AC-DC difference at frequencies up to 2 MHz for the calibration of precision LCR meters
Authors: Schurr Jürgen , Judaschke Rolf H , Awan Shakil A
Published: November 2024

We have developed novel impedance standards based on thin-film surface mount device (SMD) resistors. Due to the small dimensions of such resistors, the frequency dependence is very small and can be calculated from quantities that can be either measured or numerically calculated. For nominal resistance values in the 10 kΩ range, as for our application, the DC and AC properties of a single thin-film SMD resistor are not sufficient but can be greatly improved by connecting several thin-film SMD resistors in series. Then the calculated frequency dependence at frequencies up to 2 MHz amounts to only a few parts per million of the DC value, which is about four orders of magnitude smaller than for all conventional calculable AC-DC resistors with a similar nominal DC value. A precision inductance-capacitance-resistance (LCR) meter for frequencies up to 2 MHz, which has a resolution and a reproducibility of a few parts per million but a systematic uncertainty of up to 3000 parts per million, is used to measure two very different SMD-based resistance standards. This enables the verification of the model calculation as well as the calibration of the LCR meter and the correction of its systematic effects, both with a relative uncertainty of a few parts per million in the whole frequency range. This boost in precision enables new applications in this frequency range such as the verification of conventional calculable resistance standards, the calibration of impedance standards, and future measurements of the quantum Hall resistance.
Meta-learning-based fault diagnosis method for rolling bearings under cross-working conditions
Authors: Xie Zhijie , Zhan Hao , Wang Yu , Zhan Changshu , Wang Zhiwei , Jia Na
Published: November 2024

Accurate prediction of bearing failures is crucial for reducing maintenance costs and enhancing production efficiency in rotating machinery. However, the variable speed conditions and complex working environments encountered during operation pose significant challenges to fault diagnosis. Problems such as domain shift and insufficient sample quantity may occur during fault diagnosis under cross-working conditions, which can decrease the accuracy and generalization of deep learning algorithms. In this paper, we introduce a fault diagnosis framework grounded in meta-learning. Centered on a dual-channel feature fusion network and employing a meta-learning training paradigm, the framework not only performs well in cross-condition fault diagnosis tasks but also demonstrates superior performance in few-shot learning scenarios. Firstly, dual-channel network is used to extract the classification features of different domains, and the features are fused. Next, training is conducted using a meta-learning strategy to acquire prior knowledge, enabling rapid model adaptation to cross-working conditions and addressing the challenge of limited training samples. Finally, two public rolling bearing data sets are used to demonstrate the efficacy of the proposed method across different operational conditions. Prior to this, we selected the appropriate sample length and fusion domain through experimental validation. The proposed method also has good fault diagnosis accuracy in cross-device tasks. The experimental results verify the effective classification capability and robustness of the proposed method. Furthermore, comparisons with other meta-learning approaches confirm the superior performance of our method. The ablation experiments validated the importance and irreplaceability of each component of the proposed method.
Robust-DefReg: a robust coarse to fine non-rigid point cloud registration method based on graph convolutional neural networks
Authors: Monji-Azad Sara , Kinz Marvin , Männel David , Scherl Claudia , Hesser Jürgen
Published: November 2024

Point cloud registration is a critical process in computer vision and measurement science, aimed at determining transformations between corresponding sets of points for accurate spatial alignment. In particular, non-rigid registration involves estimating flexible transformations that map a source point cloud to a target point cloud, even under conditions of stretching, compression, or other complex deformations. This task becomes especially challenging when addressing measurement-specific issues like varying degrees of deformation, noise, and outliers, all of which can impact measurement accuracy and reliability. This paper introduces Robust-DefReg, a novel method for non-rigid point cloud registration that applies graph convolutional networks (GCNNs) within a coarse-to-fine registration framework. This end-to-end pipeline harnesses global feature learning to establish robust correspondences and precise transformations, enabling high accuracy across different deformation scales and noise levels. A key contribution of Robust-DefReg is its demonstrated resilience to various challenges, such as substantial deformations, noise, and outliers, factors often underreported in existing registration literature. In addition, we present SynBench, a comprehensive benchmark dataset specifically designed for evaluating non-rigid point cloud registration in realistic measurement scenarios. Unlike previous datasets, SynBench incorporates a range of challenges, making it a valuable tool for the fair assessment of registration methods in measurement applications. Experimental results on SynBench and additional datasets show that Robust-DefReg consistently outperforms state-of-the-art methods, offering higher registration accuracy and robustness, even with up to 45% outliers. SynBench and the Robust-DefReg source code are publicly accessible for further research and development at https://doi.org/10.11588/data/R9IKCF and https://github.com/m-kinz/Robust-DefReg, respectively.
An empirical model of carbon-ion relative biological effectiveness based on the linear correlation between radiosensitivity to photons and carbon ions
Authors: Flint David B , Bright Scott J , McFadden Conor , Konishi Teruaki , Martinus David K J , Manandhar Mandira , Ben Kacem Mariam , Bronk Lawrence , Sawakuchi Gabriel O
Published: November 2024

Objective. To develop an empirical model to predict carbon ion (C-ion) relative biological effectiveness (RBE). Approach. We used published cell survival data comprising 360 cell line/energy combinations to characterize the linear energy transfer (LET) dependence of cell radiosensitivity parameters describing the dose required to achieve a given survival level, e.g. 5% (D5%), which are linearly correlated between photon and C-ion radiations. Based on the LET response of the metrics D5% and D37%, we constructed a model containing four free parameters that predicts cells’ linear quadratic model (LQM) survival curve parameters for C-ions, α
C and β
C, from the reference LQM parameters for photons, αX
and βX
, for a given C-ion LET value. We fit our model’s free parameters to the training dataset and assessed its accuracy via leave-one out cross-validation. We further compared our model to the local effect model (LEM) and the microdosimetric kinetic model (MKM) by comparing its predictions against published predictions made with those models for clinically relevant LET values in the range of 23–107 keV μm−1. Main Results. Our model predicted C-ion RBE within ±7%–15% depending on cell line and dose which was comparable to LEM and MKM for the same conditions. Significance. Our model offers comparable accuracy to the LEM or MKM but requires fewer input parameters and is less computationally expensive and whose implementation is so simple we provide it coded into a spreadsheet. Thus, our model can serve as a pragmatic alternative to these mechanistic models in cases where cell-specific input parameters cannot be obtained, the models cannot be implemented, or for which their computational efficiency is paramount.
Triple-junction Dion–Jacobson perovskite tandem solar cells: advancing efficiency via interface optimization and broadened light absorption spectrum
Authors: Gohri Shivani , Madan Jaya , Pandey Rahul
Published: November 2024

Dion–Jacobson (DJ) perovskites have emerged as game-changers in the world of photovoltaics (PVs) due to their unique combination of advantages like cost-effective fabrication, tailorable bandgap, and exceptional efficiency. Further, in this study, MXene contacts have been utilized with 2D-perovskites solar cells to leverage the advantages of both, leading to improved stability, superior charge transport, and adjustable energy bandgap without the occurrence of pinhole effects. To further tap into the immense potential of perovskites, this study explores the power of a triple-junction All DJ perovskite tandem solar cell (ADJT-PSC) architecture. This design captures a broader spectrum of sunlight, maximizing energy harvesting and unlocking new possibilities for PV devices. In this symphony of light and power, 1.5-pentamethylenediamine (PeDA) methylammonium lead iodide (PeDAMAPb2I7) (1.98 eV), PeDAMA5Pb6I19 (1.6 eV), CsLaTa2Se7 (1.1 eV) take as the absorber layers in the top, middle, and bottom subcells, respectively. Moreover, optimizing the thickness of each perovskite layer is crucial for maximizing efficiency. This study conducted a thorough analysis and identified the ideal 350 nm/550 nm/200 nm thicknesses for the top/middle/bottom layers, respectively. Furthermore, the study explored the art of doping variation in the electron and hole transport layers. By meticulously adjusting the doping levels, ADJT-PSC can achieve a maximum efficiency of 35%.
Preparation and properties of Cu2MgSnS4 thin films and fabrication of heterojunction devices
Authors: Aravind N , Roy Ronaldo , Kathir K , Jose Edwin , Santhosh Kumar M C
Published: November 2024

Copper-based chalcogenides have garnered growing importance in the area of thin film photovoltaics. Cu2MgSnS4 (CMTS) is one of the newest materials in this family of materials. It is a p-type material which finds multiple applications in the field of photovoltaics. CMTS thin films were deposited onto soda lime glass substrates using an automated vacuum spray pyrolysis technique at a substrate temperature of 300 °C and annealed at different temperatures, from 300 °C to 375 °C in steps of 25 °C. The structural, elemental, morphological, optical, and electrical properties of the material were studied. X-ray diffraction studies showed that annealing eliminates impurity phases and improves crystallinity. Field emission scanning electron microscopy studies showed improved grain size and uniform deposition of the films. The energy bandgap of the as-prepared film is 2.02 eV and that of the annealed films is around 2.5 eV. Hall measurements show that the material exhibits p-type conductivity with high values of conductivity, mobility and bulk concentration. Heterojunction devices were fabricated with a chemical bath deposited CdS as a buffer layer and spray deposited aluminium doped zinc oxide as an n-layer. Silver contacts were placed as electrodes over the top layer. The fabricated device architecture is . The junction parameters including rectification ratio, knee voltage, series resistance and ideality factor of all the devices are calculated. The device annealed at 375 °C showed an ideality factor of 2.23, which is the best among all the fabricated devices.
Row hammer-induced D0 failure improvement in sub-20 nm DRAM using an air gap
Authors: Yoon Jiyeong , Yoon Seokchan , Ahn Jinho , Shin Changhwan
Published: November 2024

As the density of bit cells increases, reliability issues in state-of-the-art dynamic random access memory (DRAM) become critical. Row hammer (RH) is a reliability issue in sub-20 nm DRAM products. This work proposes an air gap technique (i.e. placing an air gap beneath the passing wordline (PWL)), to suppress the RH in sub-20 nm DRAM. Using 3D TCAD simulations, the electric field and Shockley–Read–Hall recombination rate are investigated when the PWL is activated. When the PWL is deactivated, the leakage current towards the bitline is extracted to investigate the impact of the air gap on RH. It turns out that a low-k dielectric material in the air gap can effectively help to reduce the electric field intensity near the interface between shallow-trench-isolation (STI) and silicon. A relatively weak electric field can prevent the flow of electrons that causes read/write errors through trap-assisted recombination. By adopting the air gap in STI, an 82% improvement was estimated in terms of alleviating RH.
Development of surface-texturized black silicon through metal-assisted chemical etching and its application in the thermophotovoltaic field: a review and recommendation
Authors: Khairul Azri A A , Wan Muhamad Hatta S F , Abdul Wahab Y , Islam M A , Mekhilef S , Ker P J , Zuhdi A W M
Published: November 2024

The Shockley–Queisser limit poses a significant challenge in solar technology research, limiting the theoretical efficiency to around 30%. Thermophotovoltaic (TPV) systems have emerged as a solution by incorporating a thermal absorber in traditional solar cell setups to achieve total efficiency beyond the limits. The efficiency of the overall system heavily depends on the performance and quality of the thermal absorber, which absorbs photons from the heat source and transfers them to the TPV cell. However, complex and expensive fabrication processes have hindered widespread adoption of TPV technology. The well-established metal-assisted chemical etching (MACE) method could be the best choice to mitigate these as it is a cost-effective, scalable, and mass-production-friendly process, which is widely used for surface texturization, creating nanostructures like nanopores, pyramids, and nanowires. MACE technique is also suitable for producing highly efficient silicon-based thermal absorbers with over 90% absorption rate, which can contribute to increased total conversion efficiency. However, it does not come without challenges such as maintaining control over the etch rate in order to achieve uniformity. This paper comprehensively reviews the utilization of MACE for fabricating silicon-based thermal absorbers in TPV systems with the range of effective wavelengths of 600–2000 nm which corresponds to the energy level of 0.55–1.85 eV. The advantages and challenges of MACE, along with characterization techniques, are extensively discussed. By providing valuable insights, this paper aims to support researchers interested in advancing TPV technology.
Light-modulated 8-Pmmn borophene-based pure crossed Andreev reflection
Authors: Cheng Renxiang , Li Mengying , Wang Hong , Xu Yafang , Li Xing’ao , Zhou Xingfei
Published: November 2024

We investigate the off-resonant circularly polarized light-modulated crossed Andreev reflection (CAR) in an 8-Pmmn borophene-based normal conductor/superconductor/normal conductor junction. When the signs of Fermi energies in two normal regions are opposite, the pure CAR without the local Andreev reflection and the elastic cotunneling occurs. By using the Dirac–Bogoliubov–de Gennes equation and the Blonder–Tinkham–Klapwijk formula, the pure CAR conductance and its oscillation as a function of the junction length and the Fermi energy in the superconducting regions are discussed. It is found that the value of pure CAR conductance peak value and its corresponding value of light-induced gap increase with the increase of incident energy of electron. Furthermore, the valley splitting for the transmitted hole is found due to the presence of tilted velocity of borophene. Our findings are beneficial for designing the high efficiency 8-Pmmn borophene-based nonlocal transistor and nonlocal valley splitter without local and non-entangled processes.
The influence of experimental imperfections on photonic GHZ state generation
Authors: Wiesner Fabian , Chrzanowski Helen M , Pieplow Gregor , Schröder Tim , Pappa Anna , Wolters Janik
Published: November 2024

While the advantages of photonic quantum computing, including direct compatibility with communication, are apparent, several imperfections such as loss and distinguishability presently limit actual implementations. These imperfections are unlikely to be completely eliminated, and it is therefore beneficial to investigate which of these are the most dominant and what is achievable under their presence. In this work, we provide an in-depth investigation of the influence of photon loss, multi-photon terms and photon distinguishability on the generation of photonic 3-partite Greenberger–Horne–Zeilinger states via established fusion protocols. We simulate the generation process for spontaneous parametric down-conversion and solid-state-based single-photon sources using realistic parameters and show that different types of imperfections are dominant with respect to the fidelity and generation success probability. Our results indicate what are the dominant imperfections for the different photon sources and in which parameter regimes we can hope to implement photonic quantum computing in the near future.
Spatial magnetic force and magnetic energy density analysis of microsphere medium in high gradient magnetic fields: a 3D simulation
Authors: Yu Xuyan , Zhan Lei , Wang Xiubin , Wang Qian , Ku Jiangang
Published: November 2024

High gradient magnetic separation technology is the key technology for green and efficient separation and purification of mineral resources. Existing studies are vague about the division of the attraction and repulsion zones of the medium, and there are fewer explorations of the effect of various conditions on the attraction zones. In this work, a novel method for calculating the magnetic force is derived, which provides an accurate calculation of the 3D magnetic force. The attraction and repulsion zones are divided clearly by analyzing the relationship between the spatial angle of the spherical medium and the magnetic force density per unit volume, with the magnetic force density per unit volume tangent to the spherical surface as the dividing line. The attraction and repulsion zones are divided by β = 30°∼35°, and the attraction region accounts for 45%∼50% of the total space volume. Furthermore, the influence of different conditions on the attraction zone is studied. It was found that the zone of attraction decreases as one moves away from the spherical medium, which results in an ellipsoid with the effective zone of attraction of the spherical medium having the magnetic field direction as its long axis. The attraction region increases from 45.49% to 49.87% of the space occupied with increasing the relative permeability of the spherical medium. It does not affect the proportion of the attraction zone in space by changing the background magnetic field and the size of the spherical medium, but it will change the depth of the magnetic force. It provides a theoretical basis for the design of high-efficiency magnetic media, and gives a reference for further improving the selection effect of high gradient magnetic separation technology on fine and weak magnetic particles.
Influence of polymer solution parameters on optical fiber Fabry-Perot polymer cavities
Authors: Kaushal Karvan , Das Bhargab
Published: November 2024

Optical fiber polymer-based Fabry–Perot sensors are frequently used to detect and quantify various physical and chemical properties. They have found significant applications in environmental monitoring, human health care, and industrial sectors. The formation of an FP cavity on the fiber end facet serves as a sensing structure for analyzing the interaction with an analyte, ultimately determining the sensor’s performance. However, the sensitivity of the sensor is directly impacted by the thickness of the FP cavity, and ensuring consistent thickness is crucial for obtaining reproducible results. Therefore, the primary aim of this study is to evaluate and establish a technique that can effectively generate a repeatable cavity on the end facet of a fiber. A simulation model is created and studies are conducted to examine the influence of polymer solution characteristics on the cavity fabrication. The experimental work involved creating polydimethylsiloxane (PDMS) polymer cavities by varying the polymer solution viscosity and examining the fluctuations in the free spectral range as well as cavity thickness. The suitability of this approach has also been assessed on a range of other polymers. The simulation and experimental results indicate that it is possible to achieve a repeatable coating thickness on the end facet of fiber, irrespective of the polymer used, by suitably controlling the solution characteristics. The findings of the study will greatly advance the fabrication of polymer-based fiber FP cavity sensors used in a diverse range of applications.
Corrected thermodynamics and stability of magnetic charged AdS black holes surrounded by quintessence
Authors: Gogoi Dhruba Jyoti , Sekhmani Yassine , Bora Shyamalee , Rayimbaev Javlon , Bora Jyatsnasree , Myrzakulov Ratbay
Published: November 2024

In this study, we explore the corrected thermodynamics of non-linear magnetic charged anti-de Sitter (AdS) black holes surrounded by quintessence, incorporating thermal fluctuations and deriving the corrected thermodynamic potentials. We analyze the effects of corrections due to thermal fluctuations on various thermodynamic potentials, including enthalpy, Helmholtz free energy, and Gibbs free energy. Our results show significant impacts on smaller black holes, with first-order corrections destabilizing them, while second-order corrections enhance stability with increasing parameter values. The specific heat analysis further elucidates the stability criteria, indicating that the large black holes ensure stability against phase transitions. However, the thermal fluctuations do not affect the physical limitation points as well as the second-order phase transition points of the black hole. Our findings highlight the intricate role of thermal fluctuations in black hole thermodynamics and their influence on stability, providing deeper insights into the behaviour of black holes under corrected thermodynamic conditions.
Cosmic topology. Part IIIa. Microwave background parity violation without parity-violating microphysics
Authors: Samandar Amirhossein , Duque Javier Carrón , Copi Craig J. , Barandiaran Mikel Martin , Mihaylov Deyan P. , Pereira Thiago S. , Starkman Glenn D. , Akrami Yashar , Anselmi Stefano , Cornet-Gomez Fernando , Eskilt Johannes R. , Jaffe Andrew H. , Kosowsky Arthur , Tamosiunas Andrius ,   The COMPACT collaboration
Published: November 2024

The standard cosmological model, which assumes statistical isotropy and parity invariance, predicts the absence of correlations between even-parity and odd-parity observables of the cosmic microwave background (CMB).
Contrary to these predictions, large-angle CMB temperature anomalies generically involve correlations between even-ℓ and odd-ℓ angular power spectrum C

ℓ
, while recent analyses of CMB polarization have revealed non-zero equal-ℓ
EB correlations.
These findings challenge the conventional understanding, suggesting deviations from statistical isotropy, violations of parity, or both.
Cosmic topology, which involves changing only the boundary conditions of space relative to standard cosmology, offers a compelling framework to potentially account for such parity-violating observations.
Topology inherently breaks statistical isotropy, and can also break homogeneity and parity, providing a natural paradigm for explaining observations of parity-breaking observables without the need to add parity violation to the underlying microphysics.
Our investigation delves into the harmonic space implications of topology for CMB correlations, using as an illustrative example EB correlations generated by tensor perturbations under both parity-preserving and parity-violating scenarios.
Consequently, these findings not only challenge the foundational assumptions of the standard cosmological model but also open new avenues for exploring the topological structure of the Universe through CMB observations.
The power spectrum of luminosity distance fluctuations in General Relativity
Authors: Pantiri Mattia , Foglieni Matteo , Dio Enea Di , Castorina Emanuele
Published: November 2024

At low redshift, it is possible to combine spectroscopic information of galaxies with
their luminosity or angular diameter distance to directly measure the projection of peculiar
velocities (PV) along the line-of-sight. A PV survey probing a large fraction of the sky is
subject to so-called wide-angle effects, arising from the variation of the line-of-sight across
the sky, and other sub-leading projection effects due to the propagation of the photons in a
perturbed cosmological background. In this work, for the first time, we provide a complete
description, within linear theory and General Relativity, of the power spectrum of luminosity
distance fluctuations, clarifying its relation to the observables in a PV survey. We find that
wide-angle effects will be detected at high significance by future observations and will have to
be included in the cosmological analysis. Other relativistic projections effects could also be
detected provided accurate, per object, distances are available.
The LAMOST Spectroscopic Survey of Supergiants in M31 and M33
Authors: Wu Hao , Huang Yang , Zhang Huawei , Yuan Haibo , Huo Zhiying , Liu Cheng
Published: November 2024

We present systematic identifications of supergiants in M31/M33 based on the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectroscopic survey. Radial velocities of nearly 5000 photometrically selected M31/M33 supergiant candidates have been properly derived from the qualified spectra released in LAMOST DR10. By comparing their radial velocities with those predicted from the rotation curve of M31, as well as utilizing Gaia astrometric measurements to exclude foreground contaminations, 199 supergiant members in M31, including 168 “Rank1” and 31 “Rank2,” have been successfully identified. This sample contains 62 blue supergiants (BSGs, all “Rank1”), 134 yellow supergiants (YSGs, 103 “Rank1” and 31 “Rank2”) and three red supergiants (RSGs, all “Rank1”). For M33, we identify 84 supergiant members (56 “Rank1” and 28 “Rank2”), which include 28 BSGs (all “Rank1”), 53 YSGs (25 “Rank1” and 28 “Rank2”) and three RSGs (all “Rank1”). So far, this is one of the largest supergiant samples of M31/M33 with full optical wavelength coverage (3700 < λ < 9100 Å). This sample is valuable for understanding star formation and stellar evolution under different environments.
JWST Observations Constrain the Time Evolution of Fine Structure Constants and Dark Energy-electromagnetic Coupling
Authors: Wang Ze-Fan , Lei Lei , Feng Lei , Fan Yi-Zhong
Published: November 2024

It was hypothesized in the literature that some physical parameters may be time-evolving and the astrophysical data can serve as a probe. Recently, the James Webb Space Telescope (JWST) released its early observations. In this work, we select the JWST spectroscopic observations of the high redshift (z > 7.1) galaxies with strong [O iii] (λ = 4959 Å and 5007 Å in the rest frame) emission lines to constraint the evolution of the fine structure constant (α). With the spectra from two galaxies at redshifts of 7.19 and 8.47, the deviation of α from its fiducial value is found to be as small as

0.44

−
8.3
−
1.7

+
8.4
+
1.7

×

10

−
4

and

−

10.0

−
18
−
1.5

+
18
+
1.5

×

10

−
4

, respectively (the first error is statistical and the latter is systematic). The combination of our results with the previous data reveals that

1

α

d
α

dt

=

0.30

−
4.5

+
4.5

×

10

−
17

yr

−
1

. Clearly, there is no evidence for a cosmic evolution of α. The prospect of further constraining the time evolution of α is also discussed. The scalar field of dark energy is hypothesized to drive the acceleration of the universe’s expansion through an interaction with the electromagnetic field. By integrating the observational data of the fine-structure constant variation,

Δ
α

α

(
z
)

, we have established a stringent upper limit on the coupling strength between dark energy and electromagnetism. Our analysis yields ζ ≤ 3.92 × 10−7 at the 95% confidence level, representing the most stringent bound to date.
Prediction of Hydrate Formation in Supercritical CO2 Containing Impurities Long-Distance Transportation Pipelines with a Capacity of 0.36 Million t/a
Authors: Tang Chunli , Chen Bing , Qi Wenjiao , Zhao Qiong , Wang Xiangzeng
Published: November 2024

Long-distance pipeline transportation is the most economical and feasible way to transport CO2. Hydrates can easily form during the transportation of supercritical CO2 containing impurities, leading to pipeline blockage. Therefore, accurate prediction of the deposition location and amount of hydrates in pipelines is crucial. This paper established a prediction model for hydrate growth in the long-distance CO2 transportation pipeline containing impurities. The phase equilibrium diagram and kinetic growth model were combined to simulate the formation behaviour of CO2 hydrate. The long-distance CO2 transportation pipeline of 0.36 million t/a in Yunlin was taken as an example. The results show that the volume of CO2 hydrate increased whereas the growth rate of CO2 hydrate gradually decreased with time. Hydrates begin to form in pipeline L11 at a distance of 35-44.3 km away from the inlet, whereas at a distance of 8.1 km away from the inlet for pipeline L12. The places with the highest amount of hydrate formation in both of the pipelines were at the end of pipelines. The area for hydrates formation in pipeline L12 was much longer than that in pipeline L11 due to the lower temperature. The cleaning cycle for pipeline L12 should be much shorter than that of pipeline L11. This paper will provide guidance for the operation of CO2 long distance pipelines.
Associating the Moon and the tide
Authors: Woodworth Philip L.
Published: November 2024

The Moon is important to us. It has played a major role in the evolution of our planet, most obviously by causing a reduction of the rotation rate of the Earth through tidal friction. It is even possible that the Moon and hence the tides could have provided one mechanism for the origin of life on Earth through the repeated flooding and drying out under the Sun of primitive organisms in inter-tidal pools [1], [2]. In addition, the Moon has been an important factor in the religions and cultures of many societies.
Taking up space: The case of the ether
Authors: Votsis Ioannis
Published: November 2024

This paper obtains some methodological lessons in theory construction and modification (generally called ‘theory choice’) using the ether as a test case. It focusses on this posit both because it has a long history but also because it is associated with some spectacular theories and theorists. In view of the fact that the ether has been expunged from contemporary science, the paper asks why it survived as long as it did, whether its discussion was a waste of space and where to go from here. The last of these questions concerns not just the ether but also similar posits currently in circulation or those that will enter circulation in years to come.
Green hydrothermal synthesis of gallic acid carbon dots: characterization and cytotoxic effects on colorectal cancer cell line
Authors: Ebrahimi Yaser , Rezaie Jafar , Akbari Ali , Rasmi Yousef
Published: November 2024

Colorectal cancer (CRC) remains a leading cause of cancer-related deaths worldwide, necessitating the development of novel therapeutic approaches. Carbon dots (CDs) have emerged as promising nanoparticles for biomedical applications due to their unique properties. Gallic acid (GA), an anticancer agent, is effective against various tumor types. This study explores the potential of gallic acid-derived carbon dots (GA-CDs) as an innovative anticancer agent against HCT-116 CRC cells, focusing on apoptosis signaling pathways. GA-CDs were synthesized using a one-pot hydrothermal method. Characterization was conducted using transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, and ultraviolet-visible (UV–vis) absorption spectroscopy. The cytotoxicity of GA and GA-CDs on HCT-116 cells was evaluated using the MTT assay at various concentrations over 24 and 48 h. Cellular uptake was assessed via fluorescence microscopy, and apoptosis was analyzed using acridine orange/propidium iodide (AO/PI) staining. Total RNA extraction followed by complementary DNA (cDNA) synthesis via reverse transcription-PCR was performed, and real time-PCR (Q-PCR) was conducted to examine the expression of apoptosis-related genes including Caspase-3, Bax, and Bcl-2. Characterization confirmed the successful synthesis of spherical GA-CDs. GA-CDs exhibited dose- and time-dependent cytotoxicity, with IC50 values of 88.55 μg ml−1 for GA-CDs and 192.2 μg ml−1 for GA after 24 h. Fluorescence microscopy confirmed the efficient uptake of GA-CDs by HCT-116 cells. AO/PI staining showed a significant increase in apoptotic cell numbers after treatment with GA-CDs. Q-PCR analysis revealed overexpression of Caspase-3 and Bax genes in GA-CD-treated cells, though no significant changes were observed in the expression of Bcl-2 or the Bax/Bcl-2 ratio. GA-CDs demonstrated potent anticancer properties by inducing apoptosis and reducing cell viability in HCT-116 cells. These findings suggest the potential of GA-CDs as a novel therapeutic agent for CRC treatment, warranting further investigation into their mechanism of action and in vivo efficacy.
Analyzing how the timing and magnitude of electricity consumption drive variations in household electricity-associated emissions on a high-VRE grid
Authors: Mayes Stepp , Peplinski McKenna , Sanders Kelly T
Published: November 2024

Electrifying the residential sector is critical for national climate change adaptation and mitigation strategies, but increases in electricity demand could drive-up emissions from the power sector. However, the emissions associated with electricity consumption can vary depending on the timing of the demand, especially on grids with high penetrations of variable renewable energy. In this study, we analyze smart meter data from 2019 for over 100 000 homes in Southern California and use hourly average emissions factors from the California Independent System Operator, a high-solar grid, to analyze household CO2 emissions across spatial, temporal, and demographic variables. We calculate two metrics, the annual household electricity-associated emissions (annual-HEE), and the household average emissions factor (HAEF). These metrics help to identify appropriate strategies to reduce electricity-associated emissions (i.e. reducing demand vs leveraging demand-side flexibility) which requires consideration of the magnitude and timing of demand. We also isolate the portion of emissions caused by AC, a flexible load, to illustrate how a load with significant variation between customers results in a large range of emissions outcomes. We then evaluate the distribution of annual-HEE and HAEF across households and census tracts and use a multi-variable regression analysis to identify the characteristics of users and patterns of consumption that cause disproportionate annual-HEE. We find that in 2019 the top 20% of households, ranked by annual-HEE, were responsible for more emissions than the bottom 60%. We also find the most emissions-intense households have an HAEF that is 1.7 times higher than the least emissions-intense households, and that this spread increases for the AC load. In this analysis, we focus on Southern California, a demographically and climatically diverse region, but as smart meter records become more accessible, the methods and frameworks can be applied to other regions and grids to better understand the emissions associated with residential electricity consumption.
On the inverse mean curvature flow by parallel hypersurfaces in space forms
Authors: Alencar Alancoc , Tenenblat Keti
Published: November 2024

We consider the inverse mean curvature flow by parallel hypersurfaces in space forms. We show that such a flow exists if and only if the initial hypersurface is isoparametric. The flow is characterized by an algebraic equation satisfied by the distance function of the parallel hypersurfaces. The solutions to the flow are obtained explicitly when the distinct principal curvatures have the same multiplicity. This is an additional assumption only for isoparametric hypersurfaces of the hyperbolic space or of the sphere with two or four distinct principal curvatures. The boundaries of the maximal interval of definition, when finite, are determined in terms of the number

g
g

of distinct principal curvatures, their multiplicities

m
m

and the mean curvature

H
H

of the initial hypersurface. We describe the collapsing submanifolds of the flow at the boundaries of the interval. In particular, we show in the Euclidean space the solutions are eternal, while in the hyperbolic space there are eternal and immortal solutions. Starting with a connected isoparametric submanifold of the sphere, we show that the flow is an ancient solution, that collapses into a minimal hypersurface whose square length of its second fundamental form and its scalar curvature are constants given in terms of

g
g

and

n
n

. The minimal hypersurface is totally geodesic when

g
=
1

g=1

, it is a Clifford minimal hypersurface of the sphere when

g
=
2

g=2

and it is a Cartan type minimal submanifold when

g
∈
{
3
,
4
,
6
}

g\in \{3,4,6\}

.
Lower-dimensional invariant tori for a class of degenerate reversible systems under small perturbations
Authors: Yang Xiaomei , Xu Junxiang
Published: November 2024

This paper considers a class of degenerate reversible systems. By the method of introducing a modified term and some KAM techniques, we prove the persistence of lower-dimensional invariant tori with prescribed frequencies.
Stories into song: theory and co-creative practice of adapting literary fiction into pop and rock songs
Authors: Bentley Nick , Peacock James
Published: November 2024

Despite the many pop and rock songs adapted from literary texts, there has been little scholarship on the theory and practice of adapting novels and short stories into short-form musical works. This article is part of a British Academy-funded pilot project carried out by two researchers at Keele University, UK. Locating story-into-song texts within adaptation studies, it explores the theoretical issues involved in such adaptations; describes the methodology employed in a series of co-creative workshops with volunteers; and analyses the original songs that emerged from the project.