bluuebunny/crossref_metadata_2025 huggingface dataset:
Les entreprises familiales en Égypte: naissance, disparition, croissance et transformation
Authors: KRAFFT Caroline
Published: November 2024

Malgré l'importance des entreprises familiales pour l'emploi dans les économies en développement, on sait peu de choses sur leur création, leur survie et leur croissance. L'autrice examine ces dynamiques à partir de données de panel égyptiennes relatives à la période 1998–2018 et cherche à les expliquer en étudiant les caractéristiques des individus, des ménages et des entreprises. Elle constate que les taux élevés de création et de disparition d'entreprises familiales influent davantage sur l'emploi que la croissance des effectifs au sein des entreprises existantes. L'entreprise familiale peut être une stratégie de survie, mais peut aussi offrir des perspectives d'enrichissement.
Dinámica de las empresas familiares en Egipto. Nacimiento, muerte, crecimiento y transformación
Authors: KRAFFT Caroline
Published: November 2024

Pese a la importancia de las empresas familiares para el empleo en las economías en desarrollo, poco se sabe acerca de su creación, supervivencia y crecimiento. Analizando datos de panel del periodo 1998–2018 en Egipto, se estudia si esa dinámica guarda relación con las características de los individuos, los hogares y las propias empresas. Se constata que el principal motor del empleo es la elevada tasa de creación y cierre de empresas familiares, antes que la dinámica de crecimiento de las empresas persistentes. Trabajar en un negocio familiar puede ser una estrategia de supervivencia para los trabajadores menos calificados y más desfavorecidos, pero también representa una oportunidad de acumulación de riqueza.
Global Invasion of Thrips parvispinus (Karny) (Thysanoptera: Thripidae) Across Three Continents Associated With Its One Haplotype
Authors: Ahmed Muhammad Z. , Roberts John W. , Soto‐Adames Felipe N. , McKenzie Cindy L. , Osborne Lance S.
Published: November 2024

Thrips parvispinus (Karny) is an exotic pest that has invaded many regions around the world in the last three decades. It was first detected in Florida in 2020 on ornamental plants (Hoya and Anthurium) in greenhouses and subsequently on ornamental plants in residential landscapes (Gardenia) in 2021. However, its first report on open vegetable field crops (Capsicum) in Florida was in 2022. We conducted field surveys and genetic analysis to answer three questions: (1) Is the population of T. parvispinus that invaded Florida the same as the one that has spread globally in the last few decades? (2) Is the host expansion to Capsicum in Florida a new population or the extension of the existing population reported on ornamental plants? and (3) What are the native and invaded distribution ranges of T. parvispinus? We analysed the genetic variation in the mitochondrial gene cytochrome oxidase I (COI) to address these questions. The global genetic diversity analysis of T. parvispinus revealed 18 haplotypes (populations) worldwide based on available data, but only one population (Hap1) invaded three continents: Africa, Europe, and North America. Based on available data, the highest haplotype diversity was observed in India, suggesting India may be part of the presumed native range (South and Southeast Asian countries) of T. parvispinus. Our survey of retail plant stores across 10 Florida counties indicated that plant trade is the source of T. parvispinus in open vegetable field crops and ornamental landscape plants. The outcome of this study will assist with regulatory and management decisions of T. parvispinus in Florida and elsewhere.
Exploring the metabolic daylength measurement system: implications for photoperiodic growth
Authors: Li Man‐Wah , Gendron Joshua M.
Published: November 2024

Photoperiod is an environmental signal that varies predictably across the year. Therefore, the duration of sunlight available for photosynthesis and in turn the ability of plants to accumulate carbon resources also fluctuates across the year. To adapt to these variations in photoperiod, the metabolic daylength measurement (MDLM) system measures the photosynthetic period rather than the absolute photoperiod, translating it into seasonal gene expression changes linked to photoperiodic growth. In this Tansley Insight, we briefly summarize the current understanding of the MDLM system and highlight gaps in our knowledge. Given the system's critical role in seasonal growth, understanding the MDLM system is essential for enhancing plant adaptation to different photoperiods and optimizing agricultural production.
Characteristics of REE enrichments in the weathered granitic crust, Toboali, South Bangka: Possibility for ion adsorption‐type REE mineralization
Authors: Agung Yusuf Zaki , Watanabe Yasushi , Tampubolon Armin , Purnama Asep Bahtiar , Rosana Mega Fatimah
Published: November 2024

This study investigates the characteristics and fractionation of rare earth elements (REEs) in the weathered products of granite from South Bangka, Indonesia. Samples were collected from two drill holes (TBKP‐30 and TBKP‐38) at depths ranging from 0.5 to 18 m. Analytical methods, including X‐ray diffraction (XRD), X‐ray fluorescence (XRF), inductively coupled plasma mass spectrometry (ICP‐MS), and scanning electron microscopy (SEM‐EDS), were used to examine mineral compositions and REE distribution. The parent granite is an S‐type biotite granite with total REE concentrations between 1081 and 1279 ppm. The dominant REE‐bearing minerals are REE‐fluorocarbonates (synchysite, parisite) and REE‐phosphates (apatite, monazite, xenotime), accompanied by REE‐silicates (allanite, thorite, zircon). Fluorocarbonates (synchysite, parisite) occur filling grain boundaries of the parental granite, suggesting later overprinting. Monazite, xenotime, and zircon were identified as part of the crystal lattice of residual minerals in both weathered profiles. TBKP‐30, has significantly depleted in REEs with high intensity degree of weathering and the occurrence of gibbsite minerals. TBKP‐38, has cerium enrichment in the lower profile, caused by the fixation into cerianite and/or it is incorporation with Fe‐Mn hydr(oxides) along with the occurrence of kaolinite minerals. This study highlights the patterns of REE enrichment as a potential indicator of weathering intensity, providing insights crucial for the exploration of REE deposits and the development of sustainable extraction methods.
Pedogenic continental red beds: How, why and when red? Redox geochemistry and quantitative colour analysis of the Old Red Sandstone, South Wales, UK
Authors: Bábek Ondřej , Ackerman Lukáš , Šimíček Daniel , Wright V. Paul , Marriott Susan , Pluháček Tomáš , Shahrokhi Salahaddin , Weinerová Hedvika
Published: November 2024

Continental red beds are coloured by secondary Fe(III)‐oxy‐hydroxides (mainly hematite) which makes them excellent archives of ancient near‐surface redox conditions. However, colour is often treated as a subjective physical property, and opinions differ widely as to the environment and timing of colouration of the red beds. This study utilizes diffuse spectral reflectance to address the degree of reddening (hematitization) of the Siluro‐Devonian Old Red Sandstone representing a dryland fluvial system with abundant palaeo‐Vertisols, coinciding with the period of land colonization by vascular plants. The hematitization was studied along with the stratigraphy, facies, pedogenic features, petrology, element and Molybdenum isotope geochemistry. The mudstones and palaeosols are typically red while sandstones are often grey. The red colouration corresponds to approximately 30 to 36% of red band (625 to 700 nm) reflectance and high hematite to goethite ratios. The red sediments contain hematitized biotite, submicronic hematite in mudstone and sandstone matrix, and hematite cement in calcretes. The hematitization was synchronous with formation of pedogenic mudcracks, Vertic slickensides, calcretes, reduction spots, sometimes hydrodynamic reworking, and accompanied by local (grain‐scale) depletion in Fe(II), enrichment in Fe(III), and mobilization of U, V, As, Cu, Zn and Mo. It is estimated that the hematite growth was rapid (several hundred to thousand years) but the average sedimentation rates were low (approximately 3 to 10 cm/kyr). Erosion led to development of reactivation surfaces separating layers with contrasting hematite content and geochemistry. It is suggested that high rates of pedogenesis and low sedimentation rates favour the reddening and may represent an important control on the formation of continental red beds. Limited levels of soil waterlogging, and the published δ13C values (−9 to −12‰ Vienna Pee Dee Belemnite) of the pedogenic carbonate, might reflect the changes in the nature of the soil biomantle during the early Devonian land colonization by vascular plants.
Topographic controls on the distribution of bioturbation in an intertidal sandflat
Authors: Melnyk Scott , Lazowski Cody N. , Dashtgard Shahin E. , Gingras Murray K.
Published: November 2024

Intertidal environments are highly dynamic and exhibit both regular and periodic fluctuations in environmental parameters. The interplay of these parameters controls the distribution and abundance of infaunal organisms resulting in sporadic bioturbation distributions that are well‐documented but not fully understood. This study investigates topographic controls on infaunal distributions at East Beach in White Rock, British Columbia, Canada. East Beach is a sandy intertidal flat characterized by sand dunes that give rise to two alternating shore‐parallel subenvironments: topographically high dune crests and topographically low interdunes. The dunes remain relatively fixed in their position between major storm events, resulting in geographically stable subenvironments. Photogrammetric reconstructions of dune surfaces are used to characterize surface features and quantify invertebrate burrow openings along dune profiles. This is supplemented by X‐ray radiography and examinations of porewater and organic matter content from the two subenvironments. These results show a clear inverse relationship between burrow abundance and elevation at the dune scale, with the interdunes displaying significantly higher bioturbation intensities compared to dune crests. The burrow distributions appear to be strongly influenced by water saturation, presumably due to its role in controlling oxygen availability and preventing desiccation. This research provides insights into the local factors controlling infaunal distributions and the impact of palaeo‐topography on bioturbation, particularly in intertidal settings. Additionally, these data assist in interpreting heterogeneous bioturbation distributions in the sedimentary record, which are normally not interpreted due to a paucity of analogue models developed in modern environments.
Post‐Truth GIS
Authors: Warf Barney
Published: November 2024

“Truth,” it turns out, is rather slippery. As geographers have become increasingly sensitized to issues of representation, they have delved into varying understandings of truth as a social construction. Most recently, the question of post‐truth has become significant. While cartographers have long discussed this issue, such as lying with maps and maps as propaganda, the GIS community has been slow to discuss it. This paper situates the emerging nexus between GIS and post‐truth within the evolving tradition of critical GIS. It calls for abandoning the correspondence theory of truth and replacing it with the pragmatist one. Next, it summarizes the contours of post‐truth as a social and epistemological phenomenon. Finally, it points to several areas in which post‐truth and GIS intersect, including the mapping of disinformation, location spoofing, big data, deepfake videos and remote sensing, and data quality. It concludes by calling for the GIS community to abandon unrealistic notions of objectivity and instead become more socially and politically self‐conscious.
Synthetic minichromosomes in plants: past, present, and promise
Authors: Birchler James A. , Kelly Jacob , Singh Jasnoor , Liu Hua , Zhang Zhengzhi , Char Si Nian , Sharma Malika , Yang Hua , Albert Patrice S. , Yang Bing
Published: November 2024

The status of engineered mini‐chromosomes/artificial chromosomes/synthetic chromosomes in plants is summarized. Their promise is that they provide a means to accumulate foreign genes on an independent entity other than the normal chromosomes, which would facilitate stacking of novel traits in a way that would not be linked to endogenous genes and that would facilitate transfer between lines. Centromeres in plants are epigenetic, and therefore the isolation of DNA underlying centromeres and reintroduction into plant cells will not establish a functional kinetochore, which obviates this approach for in vitro assembly of plant artificial chromosomes. This issue was bypassed by using telomere‐mediated chromosomal truncation to produce mini‐chromosomes with little more than an endogenous centromere that could in turn be used as a foundation to build synthetic chromosomes. Site‐specific recombinases and various iterations of CRISPR‐Cas9 editing provide many tools for the development and re‐engineering of synthetic chromosomes.
Geometric algebra for multibody dynamics. Part I: Elements of geometric algebra
Authors: Bauchau Olivier
Published: November 2024

Multibody systems are characterized by two distinguishing features: system components undergo finite motions and these components are connected by mechanical joints that impose restrictions on their relative motion. Clearly, kinematics plays a fundamental role in the analysis of these systems: it is required to describe the arbitrary motion of system components and is needed once again to evaluate the finite relative motion of these components where they are connected by mechanical joints. Hence, it is not surprising that numerous kinematics formulations have been used to describe multibody systems, in an effort to achieve simplicity of the formulation, freedom from singularities, and computational efficiency. Geometric algebra is a mathematical framework that provides an elegant, singularity free description of geometrical entities such as points, lines, and planes. These geometric entities can be moved in space via reflections, translations, rotations, and motions operations that are based on the “geometric product,” a singularity-free mathematical operation that involves algebraic manipulations only. Although it has received little attention in multibody dynamics, geometric algebra is widely used in computer graphics. The goal of this paper is to demonstrate that geometric algebra is a sound basis for describing the kinematics of multibody systems and for performing all required operations on the relevant geometric entities.
Effect of Piston Ring Grooves on the Radial and Tangential Forces of a Squeeze Film Damper
Authors: Giampaolo Emanuele , Arghir Mihai , Festjens Hugo
Published: November 2024

Squeeze film dampers (SFDs) are components of rotating machinery used to reduce vibration amplitudes and improve the rotor dynamic stability. Piston rings (PRs) are often employed as end seals for SFDs. They enhance the damping forces while remaining limited to a small axial length. Piston rings are installed in grooves whose dimensions (width and depth) are generally one order of magnitude larger than the radial clearance of the SFD. The radial and axial clearances after the PR are mounted may impact the forces generated by the SFD to the point that they have to be considered as design parameters. Computational fluid dynamics (CFD) and bulk flow (BF) approaches were used to determine the impact of the axial and radial clearances introduced by the presence of the PRs. CFD is an accurate, direct approach to the problem but it requires intensive computational resources. Therefore, BF-based methods are considered as an appropriate option for a wide range of SFD operating conditions. The BF approach developed previously is now extended to include the PR clearances. The results are validated using CFD simulations for a simplified SFD geometry. This comparison underlines the strengths and limits of the BF approach. The impact of the PR clearances on the radial and tangential forces is then evaluated on a realistic SFD by using the BF model. A parametric study is conducted to explore the impact of varying the axial and radial PR clearances. Overall, a procedure for correctly considering PR clearances in a BF framework is proposed and validated, while complementary elements for understanding the role of PR clearances are described.
Numerical Study on Transient Flow Boiling Performance of the Microchannels With Grooved Pin Fins
Authors: Wang Shuang , Ke Zhiwu , Zheng Wei , Lin Mei , Wang Qiuwang
Published: November 2024

The microchannel flow boiling cooling technology has excellent developmental potential in high heat flux electronic devices. Saturated flow boiling in a microchannel with V-shaped grooved pin fins is simulated using the volume of fluid (VOF) model. The working coolant is Novec649. The depth-to-width ratio β of a single groove is set as 0, 1, and 2, respectively. The results show that with the increase of β, the maximal average temperature of heated walls decreases, and at q = 100, 300, and 500 kW·m−2, the average temperature at β = 2 declined 1.5, 5.3, and 9.3 K, respectively, compared with that at β = 0. The corresponding pressure drops are decreased by 24%, 25%, and 24%, respectively. The corresponding heat transfer factor remarkably increases 14–40%. Moreover, the model with β = 1 has the superior heat transfer coefficient while the model with β = 2 has the best comprehensive heat transfer factor as a whole.
A Chebyshev collocation method for directly solving two-dimensional ocean acoustic propagation in linearly varying seabed
Authors: Ma Xian , Wang Yongxian , Zhu Xiaoqian , Zhou Xiaolan , Tu Houwang , Xu Guojun , Gao Dongbao , Zhou Hefeng
Published: November 2024

It is one of the most concerning problems in hydroacoustics to find a method that can calculate the acoustic propagation accurately and adapt to the variation of the seabed. Currently, the one-dimensional spectral method has been employed to address the simplified ocean acoustic propagation model successfully. However, due to the model's application limitations and approximation error, it poses challenges when attempting to solve real-world ocean acoustic fields. Hence, there is a crucial need to develop a direct solution method for the two-dimensional Helmholtz equation of ocean acoustic propagation, without relying on a simplified model. In previous work, we achieved successful solutions for the two-dimensional Helmholtz equation within a rectangular domain, utilizing a collocation-type spectral method. Taking into account the fluctuations in the actual seabed, we introduce a Chebyshev collocation spectral method to directly tackle the two-dimensional ocean acoustic propagation problem, which could solve the case of a seabed with linear variation, sound velocity variation and inhomogeneous medium situation. After comparative verification, the calculation result of the two-dimensional spectral method is more accurate than traditional mature models such as Kraken and COUPLE. By eliminating model constraints and enlarging the solution range, this spectral method holds immense potential in real marine environments.
Testing the role of temporal coherence on speech intelligibility with noise and single-talker maskers
Authors: Lee Jaeeun , Oxenham Andrew J.
Published: November 2024

Temporal coherence, where sounds with aligned timing patterns are perceived as a single source, is considered an essential cue in auditory scene analysis. However, its effects have been studied primarily with simple repeating tones, rather than speech. This study investigated the role of temporal coherence in speech by introducing across-frequency asynchronies. The effect of asynchrony on the intelligibility of target sentences was tested in the presence of background speech-shaped noise or a single-talker interferer. Our hypothesis was that disrupting temporal coherence should not only reduce intelligibility but also impair listeners' ability to segregate the target speech from an interfering talker, leading to greater degradation for speech-in-speech than speech-in-noise tasks. Stimuli were filtered into eight frequency bands, which were then desynchronized with delays of 0–120 ms. As expected, intelligibility declined as asynchrony increased. However, the decline was similar for both noise and single-talker maskers. Primarily target, rather than masker, asynchrony affected performance for both natural (forward) and reversed-speech maskers, and for target sentences with low and high semantic context. The results suggest that temporal coherence may not be as critical a cue for speech segregation as it is for the non-speech stimuli traditionally used in studies of auditory scene analysis.
Frequency-domain sound field from the perspective of band-limited functions
Authors: Iwami Takahiro , Omoto Akira
Published: November 2024

A model that approximates the sound field well is useful in various fields, such as acoustic signal processing and numerical simulation. We have proposed an effective model in which the wideband instantaneous sound field is regarded as an element of a spherically band-limited function space, using the reproducing kernel of that space. In this paper, the frequency-domain sound field is regarded as an element of some band-limited function space, and a representation of the field as a linear combination of the reproducing kernel in that space is proposed. This model has the strongest representational capacity of all function systems when we know only the sound pressure information at arbitrary positions. The proposed model can be considered a generalization of the existing three-dimensional sound field model using the reproducing kernel of the solution space of the Helmholtz equation to the spatial dimension. One of the advantages of capturing the frequency-domain sound field in this way is the simplicity achieved for the estimation formula of the wavenumber spectrum. Two numerical simulations were conducted to validate the proposed methods.
Electroweak metastability and Higgs inflation
Authors: Masina Isabella , Quiros Mariano
Published: November 2024

Extrapolating the Standard Model Higgs potential at high energies, we study the barrier between the electroweak and Planck scale minima. The barrier arises by taking the central values of the relevant experimental inputs, that is the strong coupling constant and the top quark and Higgs masses. We then extend the Standard Model by including a non-minimal coupling to gravity, and explore the phenomenology of the Higgs inflation model. We point out that even configurations that would be metastable in the Standard Model, become viable for inflation if the non-minimal coupling is large enough to flatten the Higgs potential at field values below the barrier; we find that the required value of the non-minimal coupling is smaller than the one needed for the conventional Higgs inflation scenario (which relies on a stable Standard Model Higgs potential, without any barrier); in addition, values of the top mass which are larger than those required in the conventional scenario are allowed.
Thermodynamics and kinetics of state switching for the asymptotically flat black hole in a cavity
Authors: Li Ran , Wang Jin
Published: November 2024

We propose that the thermodynamics and the kinetics of state switching for the asymptotically flat black hole enclosed by a cavity can be studied in terms of the free energy landscape formalism. The generalized free energy for the black hole enclosed by a cavity in the canonical ensemble is derived by using the York’s approach, where the temperature on the cavity and the charges inside the cavity are kept as the fixed parameters. By quantifying the corresponding free energy landscape, we obtain the phase diagrams for the black hole in cavity, which reveal a Hawking–Page type transition for the uncharged black hole and a Van der Waals type transition for the charged black hole. We further assume that the dynamics of black hole state switching is mutually determined by the gradient force and the stochastic force arising from the free energy landscape and the thermal noises respectively. We then derive a recurrence relation for the n-momentum of the first passage time distribution function, which enables the calculation of the kinetic times characterized by the mean first passage time and its relative fluctuation. Our analysis illustrates that the kinetics of black hole state switching is determined by the ensemble temperature and the barrier height on the free energy landscape.
Charged Dyson shells supported in curved spacetimes of spherically symmetric central compact objects
Authors: Hod Shahar
Published: November 2024

It is proved that charged thin shells (charged Dyson shells) can be supported in unstable static equilibrium states around spherically symmetric central compact objects. The regime of existence of the composed central-compact-object-static-charged-shell configurations is characterized by the inequalities $$\sqrt{m(m+2M)}<|q|<M+\sqrt{M^2+m^2}$$

m
(
m
+
2
M
)

<

|
q
|

<
M
+

M
2

+

m
2

, where $$\{m,q\}$$

{
m
,
q
}

are respectively the proper mass and the electric charge of the supported shell and M is the mass of the central compact object (a black hole or an horizonless compact star). We reveal the physically interesting fact that the supported charged shells become marginally-stable in the $$|q|/\sqrt{m(m+2M)}\rightarrow 1^+$$

|
q
|

/

m
(
m
+
2
M
)

→

1
+

limit, in which case the lifetime (instability timescale) of the composed system can be made arbitrarily large. Our analysis goes beyond the test shell approximation by properly taking into account the exact gravitational and electromagnetic self-interaction energies of the spherically symmetric shell in the curved spacetime. In particular, the existence of the composed compact-object-charged-shell static configurations in the Einstein–Maxwell theory is attributed to the non-linear electromagnetic self-energy of the supported shell.
THE IMPACT OF TRADE POLICY UNCERTAINTY ON THE DOMESTIC TECHNOLOGICAL CONTENT OF EXPORT PRODUCTS: EVIDENCE FROM CHINESE MANUFACTURING FIRMS
Authors: LIU HAIYUN , QIAN HUIHUI
Published: November 2024

This study provides a novel evaluation of the domestic technological content of firms’ exports, with an emphasis on production processes. It uses China’s accession to WTO as a quasi-natural experiment to examine the effect of decreased trade policy uncertainty (TPU) on the domestic technological content of firms’ exports. There is a significant correlation between decreased TPU and an increase in the domestic technological content of firms’ exports, according to the findings. In particular, the reduction in TPU contributes to an increase in domestic technology content primarily by stimulating innovation, boosting productivity and provoking export reallocation. In addition, the impact of reduced TPU is more pronounced in improving the domestic technological content of exports for firms with lower initial productivity and capital intensity. This study offers policy implications for developing countries seeking to enhance export technology through trade policies.
Revolutionizing Brain Tumor Diagnosis: A Comprehensive Model Integrating VGG19 and LSTM for Accurate MRI Classification
Authors: Venkatachalam Chandrasekar , Umamaheswari M. , Shah Priyanka , Thakur Arastu
Published: November 2024

Diagnosing brain tumors is particularly difficult because they can grow in unpredictable ways and look very different on MRI scans. The current methods used to automatically identify these tumors often struggle because of the wide variety of tumor types and the complex structure of the brain. As a result, these methods don’t always classify tumors accurately, which can affect patient treatment and outcomes. The main problems with these methods are that they find it hard to distinguish between different types of tumors accurately and to deal with the various ways tumors can appear on MRI scans. To improve this situation, our study integrates the robust image classification capabilities of VGG19 with the sequential data processing strengths of LSTM. This synergistic approach enhances our model’s ability to accurately classify various types of brain tumors from MRI scans, addressing the inherent challenges associated with tumor heterogeneity in medical imaging. VGG19, a deep convolutional neural network, is employed to extract detailed features from MRI scans, facilitating precise tumor characterization based on visual patterns and LSTM complements VGG19 by capturing temporal dependencies in the sequential data of MRI scans, enabling the model to discern subtle variations in tumor appearances over time. By leveraging the combined power of VGG19 and LSTM architectures, our study achieves significant advancements in the accurate classification of brain tumors from MRI images. This approach not only enhances diagnostic precision but also lays the groundwork for future improvements in neuro-oncological imaging diagnostics. Our study includes 1000 patients evaluated with MRI for brain tumors. We achieved an overall accuracy of 98.32% demonstrating the efficacy of our VGG19-LSTM model in accurate tumor classification. By using both, our model aims to get better at understanding MRI scans and, as a result, be more accurate at identifying brain tumors. This combination is a new step forward in making brain tumor diagnosis more precise through a detailed and cooperative approach using neural networks.
A Finite Element Approach for Forced Dynamical Responses of Porous FG Nanocomposite Beams Resting on Viscoelastic Foundations
Authors: Tounsi Abdeldjebbar , Belabed Zakaria , Bounouara Fatima , Balubaid Mohammed , Mahmoud S. R. , Bousahla Abdelmoumen Anis , Tounsi Abdelouahed
Published: November 2024

In this paper, a comprehensive dynamical analysis of porous-reinforced carbon nanotube (CNT) nanocomposite beams on viscoelastic foundations is presented. Using a three-unknown shear beam theory, the two-nodded finite element model was formulated and adapted for both [Formula: see text] and [Formula: see text] continuities for displacement variables. This model captured the distinct characteristics and interactions of the porous medium, CNT reinforcements, and the intrinsic damping introduced by the viscoelastic foundation. The dynamical investigation incorporates both free and forced vibration analysis, and the Newmark method is employed for time-dependent analysis, ensuring accurate temporal behavior prediction. The study also emphasizes the impact of different CNT distribution patterns and porosity variations on the mechanical properties of the beams, particularly in terms of stiffness and damping characteristics. Further depth is added by analyzing the interactions between beams and both Winkler and Pasternak foundation models, with findings that highlight the importance of foundation parameters in the overall dynamic response. The results shed light on the critical role each component plays in the composite beam’s dynamic response, offering insights for potential innovative designs and applications in both advanced structural engineering and nanotechnology domains.
Controlled and assisted cloning of two-, three- and four-qubit states with optimal quantum resources
Authors: Maihemuti Nueraminaimu , Peng Jiayin , Aisan Yimamujiang , Tang Jiangang
Published: November 2024

Utilizing Hadamard gates and controlled not gates, maximally entangled states of four, five and six qubits are generated. Then, we propose respectively controlled and assisted cloning schemes of unknown two-, three- and four-qubit states via these constructed states as quantum channels. Each of the three schemes includes two stages: controlled teleportation and assisted cloning. The controlled teleportation stage of our schemes all require a single-qubit [Formula: see text]-basis measurement by controller, and need different GHZ-state measurements by senders of three schemes to complete the transmission process of their respective quantum states. In the assisted cloning stage of our schemes, after the state preparers of three schemes perform respectively appropriate GHZ-state measurements, at the senders’ locations, perfect replicas and orthogonal complementary copies of unknown states will be produced through appropriate local quantum operations. Compared with usual assisted cloning schemes, every suggested plan is extremely efficient in terms of quantum resources, as it only requires a small number of GHZ-state measurements, significantly decreasing the need for quantum operations and classical resources. Through discussion, we conclude that our schemes are safe and can be extended to assisted cloning of unknown multi-qubit GHZ-state with multiple controllers.
Symmetric midpoint-type inequalities for (α,m)-convex functions with applications
Authors: Hussain Rashida , Gulshan Ghazala , Rehman Amara , Budak Hüseyin
Published: November 2024

In this study, we establish a modified version of the right symmetric quantum midpoint-type inequalities via ([Formula: see text], [Formula: see text])-convex differentiable functions with [Formula: see text]. A few fundamental inequalities like Power mean and Hölder’s have been applied to acquire recent results. The newly established findings can be changed into classical midpoint-type inequalities as well as [Formula: see text]-midpoint-type inequalities for convex functions. Additionally, we provide an example and graph that support our main findings. It is supposed that these concepts and methods may encourage new analysis.
A pure geometric field theory with parameterized canonical W-tensor
Authors: Wanas M. I. , Youssef Nabil L. , Nabil Samah , Abdelghany Aya M.
Published: November 2024

This paper presents a pure geometric field theory within the framework of Parameterized Absolute Parallelism geometry, aiming to exceed the limitations of both Riemannian and Absolute Parallelism geometries. Following the Unification Principle, the theory employs Parameterized Absolute Parallelism geometry, which involves a linear connection with nonvanishing torsion, nonvanishing curvature and nonvanishing W-tensor. The presented theory is constructed following the Dolan–McCrea variational method to derive the field equations. The theory is shown to incorporate gravity and electromagnetic features. By studying the connection between physical quantities and geometric objects, Poisson and Laplace equations are obtained in the linearized version of the theory. In free space, the Schwarzschild exterior solution of general relativity holds in the present theory.
Gauge fixing in QFT and the dressing field method
Authors: Guillaud Mathilde , Lazzarini Serge , Masson Thierry
Published: November 2024

In this paper, we revisit the dressing field method (DFM) in the context of quantum (gauge) field theories (QFT). In order to adapt this method to the functional path integral formalism of QFT, we depart from the usual differential geometry approach used so far to study the DFM which also allows to tackle the infinite dimension of the field spaces. Our main result is that gauge fixing is an instance of the application of the DFM. The Faddeev–Popov gauge fixing procedure and the so-called unitary gauge are revisited in light of this result.
Holomorphic manifolds and lifts in the bundle of 2-jets
Authors: Salimov Arif , Gurbanova Narmina
Published: November 2024

Considering the bundle of 2-jets as a realization of the holomorphic manifold over three-dimensional nilpotent algebra, we introduce a new class of lifts of (1,1)-tensor fields to the bundle of 2-jets and Norden structures concerning the diagonal lifts are studied. Einstein structures in subspaces of the bundle of 2-jets with the locally product structure are considered and a special construction of the Ricci curvature tensor in the bundle was found
The generalized stockwell transform associated with the spherical mean operator and uncertainty principles
Authors: Ghobber Saifallah , Mejjaoli Hatem
Published: November 2024

Stockwell theory is often seen as an alternative to time-frequency analysis, and it has many roots and becomes an interdisciplinary field combining harmonic analysis, applied mathematics and signal and data processing. In this paper, we will prove several uncertainty principles for the generalized Stockwell transform associated with the spherical mean operator, which set restrictions on the time-frequency behavior of a signal, such as Heisenberg-type, Shannon-type and local uncertainty principles. As a side result, by following the Donoho–Stark criterion, we will derive a sufficient condition by means of which one can recover a signal from the knowledge of a truncated version.
A glimpse into quantum gravity: A noncommutative spacetime results in quantization of area, mass and entropy
Authors: Perelman Carlos Castro
Published: November 2024

It is shown how a noncommutative spacetime leads to an area, mass and entropy quantization condition which allows to derive the Schwarzschild black hole entropy [Formula: see text], the logarithmic corrections, and further corrections, from the discrete mass transitions taking place among different mass states in [Formula: see text]. The higher-dimensional generalization of the results in [Formula: see text] follows. The discretization of the entropy-mass relation [Formula: see text] leads to an entropy quantization of the form [Formula: see text], such that one may always assign [Formula: see text] “bits” to the discrete entropy, and in doing so, make contact with quantum information. The physical applications of mass quantization, like the counting of states contributing to the black hole entropy, black hole evaporation, and the direct connection to the black holes-string correspondence [G. Horowitz and J. Polchinski, A correspondence principle for black holes and strings, Phys. Rev. D 55 (1997) 6189.] via the asymptotic behavior of the number of partitions of integers, follows. To conclude, it is shown how the recent large [Formula: see text] Matrix model (fuzzy sphere) of C.-S. Chu [A matrix model proposal for QG and the QM of black holes, preprint, arXiv:2406.01466] leads to very similar results for the black hole entropy as the physical model described in this work which is based on the discrete mass transitions originating from the noncommutativity of the spacetime coordinates.
Effect of Doped Carbon Atoms on Electronic Structure and Optical Properties of Monolayer 1T-ZrS2
Authors: Shi Zhihong , Wang Ying , Ji Jinghan , Liu Guili , Zhang Guoying
Published: November 2024

In this paper, a method based on density functional theory is used to replace varying numbers of sulfur atoms with carbon atoms in the original monolayer ZrS2 system, resulting in a new doped system. The theory is based on the First Principle. The photovoltaic properties of the new carbon-atom doping systems have been calculated and investigated. The pristine system and the carbon-atom doped systems were structurally optimized using the automatic optimization method. It was found that the stability of the structure decreases as the number of carbon atoms increases. Pristine monolayer 1T-ZrS2 is an indirect bandgap material. The results show that after doping carbon atoms in monolayer 1T-ZrS2, the p-type conductivity of the system increases and exhibits metallicity. The density of states analysis shows that the conduction band consists mainly of S-3p, Zr-4d, Zr-4p, Zr-5s and C-2p orbitals, while the valence band consists mainly of S-3p, S-3s, Zr-4d, C-2p and C-2s orbitals. It is concluded that strong hybridization between Zr-d and S-p orbitals is exhibited by both the pristine and doped systems. The analysis of the optical properties shows that the peak absorption coefficient and reflectivity peaks are blue-shifted in the doped system, and these peaks are lower than in the pristine system. The peaks of the real and imaginary parts of the dielectric function are also blue shifted. With the increase of doping concentration, the system’s energy loss decreases, indicating that proper doping can effectively reduce the system’s energy loss. The above studies provide theoretical support for applying ZrS2 in nano-optoelectronics.
Periodic Galerkin approximations for Lotka–Volterra equations using trigonometric basis functions
Authors: Karaçayır Murat
Published: November 2024

Our main interest in this study is to obtain approximate time-dependent solutions of the Lotka–Volterra predator–prey model given the populations of both species at a certain time. We achieve this by considering an earlier scheme by Shinohara and Yamamoto and modifying it so as to address the initial conditions. An important feature of this scheme is that it treats the system’s period as an unknown variable, making it possible to calculate it as a side product. In this method, the Galerkin procedure is utilized to convert the problem to a system of nonlinear algebraic equations, where sine and cosine waves are chosen as the basis functions in order to ensure the periodicity of solutions. The resulting overdetermined system is then solved in a least squares sense, which yields the coefficients making up the Galerkin approximations. After a detailed presentation of the numerical scheme, we apply it to two example problems and evaluate the results according to several accuracy criteria.
A unique way to mitigate service level agreement violation with sensor system energy saving
Authors: Krishna Kosuru Sivarama , Midhunchakkaravathy Divya , Hussain Mohammed Ali
Published: November 2024

Cloud service companies can increase the return on their investments by lowering the energy usage of their data centers, but they must also make sure that the services they supply satisfy the diverse needs of their customers. In this paper, we provide a resource management technique to lower cloud data centers energy consumption and Service Level Agreement (SLA) violations. SLA violations owing to workload are also not taken into account by current methods. We developed a novel strategy to address the aforementioned problems, which is extremely beneficial for decreasing SLA violation as well as lowering energy loss. The results were significantly improved when compared to the current state-of-the-art approaches in terms of OSLAV, VM Migrations (Virtual Machine), Throughput, Average response Time, and Performance degrade. From the proposed method the average values obtained in terms of the parameters OSLAV, performance degradation, throughput, average response time and VM migration are 2.3%, 6.76%, 37%, 247.5[Formula: see text]ms, 582.
High-Order Van Hove Singularities and Their Connection to Flat Bands
Authors: Classen Laura , Betouras Joseph J.
Published: November 2024

The flattening of single-particle band structures plays an important role in the quest for novel quantum states of matter owing to the crucial role of interactions. Recent advances in theory and experiment made it possible to construct and tune systems with nearly flat bands, ranging from graphene multilayers and moiré materials to kagome metals and ruthenates. Although theoretical models predict exactly flat bands under certain ideal conditions, evidence was provided that these systems host high-order Van Hove points, i.e., points of high local band flatness and power-law divergence in energy of the density of states. In this review, we examine recent developments in engineering and realizing such weakly dispersive bands. We focus on high-order Van Hove singularities and explore their connection to exactly flat bands. We provide classification schemes and discuss interaction effects. We also review experimental evidence for high-order Van Hove singularities and point out future research directions.
A Multiple‐Point Deformation Monitoring Model for Ultrahigh Arch Dams Using Temperature Lag and Optimized Gaussian Process Regression
Authors: Wu Bangbin , Niu Jingtai , Deng Zhiping , Li Shuanglong , Jiang Xinxin , Qian Wuwen , Wang Zhiqiang
Published: November 2024

Existing dam displacement statistical methods simulate the thermal effects using simple harmonic functions ignoring the effects of ice periods, extreme heat, and seasonal weather. Moreover, existing data‐driven methods usually utilize a separate modeling strategy, inevitably ignoring the spatiotemporal correlation of multiple displacement points in dams, resulting in poor predictive performance. To overcome these shortcomings, this study proposes a novel machine learning (ML)—aided multiple‐point dam displacement predictive model considering the temperature hysteresis effect. Firstly, an improved hydraulic‐Air_temperture_Time (HTairT) statistical monitoring model is developed using the measured air temperature lagging monitoring data. On this basis, the multitask Gaussian process regression (multipoint GPR) algorithm with an improved kernel function to construct a multipoint deformation prediction model for ultrahigh arch dams. Then, the improved meta‐heuristic physics‐driven Frost algorithm is utilized to determine the optimal parameters of the multipoint GPR model. A high arch dam with a height of 305 m is used as the case study, and five displacement monitoring points are used for validation. Five advanced ML‐based algorithms are used to comparatively evaluate and verify the performance of the proposed method in terms of forecast accuracy and interpretability. The HTairT statistical model can better simulate the hysteresis effect of temperature on dam deformation. Moreover, the Frost‐optimized dam multipoint displacement prediction model with the RQ kernel functions outperforms the other comparison methods in terms of R2, mean absolute error (MAE), and root mean squared error (RMSE) evaluation indicators. This indicates the proposed method can mine the spatiotemporal correlation among multiple monitoring points of ultrahigh arch dams, further improving the overall deformation prediction and uncertainty estimation.
Coordinated Optimization of Virtual Power Plants Based on Peer‐to‐Peer Transactions and Nash Bargaining Approach
Authors: Li Jie , Guo Jianwei , Li Xue , Liang Wenteng , Zhang Jiannan , Yang Bin , Liang Fang , Yu Xiao
Published: November 2024

Distributed power supply has seen a significant rise because of the increasing demand for renewable energy. This rise has also presented various challenges, including independent operation and a lack of coordination among the sources. As a result of these challenges, these distributed power supplies are combined into a virtual power plant (VPP). This paper addresses these issues of interaction and coordination with a proposal for multitype VPP and modeling technology. First, it recommends establishing a peer‐to‐peer (P2P) transaction framework. Second, Nash bargaining cooperative game theory comes into play, which involves multiple stakeholders in establishing a P2P transaction framework among stakeholders. After that, this proposed model is solved using the alternating direction multipliers method (ADMM). In the end, the verification of this proposed model is achieved by the numerical example that ensures that the VPP alliance operates stably.