Hasil untuk "Physics"

Alán Aspuru-Guzik, P. Walther

O. Morsch, M. Oberthaler

R. Landauer

M. Dolinski, A. Poon, W. Rodejohann

Neutrinoless double-beta decay is a forbidden, lepton-number-violating nuclear transition whose observation would have fundamental implications for neutrino physics, theories beyond the Standard Model, and cosmology. In this review, we summarize the theoretical progress to understand this process, the expectations and implications under various particle physics models, and the nuclear physics challenges that affect the precise predictions of the decay half-life. We also provide a synopsis of the current and future large-scale experiments that aim to discover this process in physically well-motivated half-life ranges.

R. Adhikari, M. Agostini, N. A. Kỳ et al.

We present a comprehensive review of keV-scale sterile neutrino Dark Matter, collecting views and insights from all disciplines involved—cosmology, astrophysics, nuclear, and particle physics—in each case viewed from both theoretical and experimental/observational perspectives. After reviewing the role of active neutrinos in particle physics, astrophysics, and cosmology, we focus on sterile neutrinos in the context of the Dark Matter puzzle. Here, we first review the physics motivation for sterile neutrino Dark Matter, based on challenges and tensions in purely cold Dark Matter scenarios. We then round out the discussion by critically summarizing all known constraints on sterile neutrino Dark Matter arising from astrophysical observations, laboratory experiments, and theoretical considerations. In this context, we provide a balanced discourse on the possibly positive signal from X-ray observations. Another focus of the paper concerns the construction of particle physics models, aiming to explain how sterile neutrinos of keV-scale masses could arise in concrete settings beyond the Standard Model of elementary particle physics. The paper ends with an extensive review of current and future astrophysical and laboratory searches, highlighting new ideas and their experimental challenges, as well as future perspectives for the discovery of sterile neutrinos.

J. Blas, M. Cepeda, J. D’Hondt et al.

This document aims to provide an assessment of the potential of future colliding beam facilities to perform Higgs boson studies. The analysis builds on the submissions made by the proponents of future colliders to the European Strategy Update process, and takes as its point of departure the results expected at the completion of the HL-LHC program. This report presents quantitative results on many aspects of Higgs physics for future collider projects of sufficient maturity using uniform methodologies.

Suraj Sharma, Ravinder Kumar

  This study explores the dispersion characteristics of Love-type surface waves in a composite elastic media consisting of an isotropic thermoelastic layer resting over nonhomogeneous elastic half-space. A rectangular-shaped irregularity at the interface between the two media is introduced to simulate a geometric discontinuity, which represents more realistic subsurface features. The present work simultaneously incorporates material inhomogeneity, thermoelastic effects, and interface irregularity within a unified analytical framework. The governing equations have been taken using theory of elasticity and solved analytically using Fourier and inverse Fourier transformations. Perturbation method is then applied to derive the dispersion equation for the propagation of Love waves. This dispersion equation is graphically analysed using MATLAB to observe how the dimensionless phase velocity changes with dimensionless wave number for different values of the inhomogeneity parameter and various values of the ratio of irregularity depth to layer height. The obtained results show that both rectangular-shaped interface irregularity and inhomogeneity significantly affect phase velocity, particularly at the lower wave numbers. This study enhances the understanding of surface wave behaviour in complex elastic structures and provides practical implications for subsurface imaging, seismic hazard assessment, and material characterization in civil engineering and geotechnical applications.

R.A. Pitts, A. Loarte, T. Wauters et al.

To mitigate the impact of technical delays, provide a more rationalized approach to the safety demonstration and move forward as rapidly as possible to a reactor relevant materials choice, the ITER Organization embarked in 2023 on a significant re-baselining exercise. Central to this strategy is the elimination of beryllium (Be) first wall (FW) armour in favour of tungsten (W), placing plasma-wall interaction (PWI) centre stage of this new proposal. The switch to W comes with a modified Research Plan in which a first “Start of Research Operation” (SRO) campaign will use an inertially cooled, temporary FW, allowing experience to be gained with disruption mitigation without risking damage to the complex water-cooled panels to be installed for later DT operation. Conservative assessments of the W wall source, coupled with integrated modelling of W pedestal and core transport, demonstrate that the elimination of Be presents only a low risk to the achievement of the principal ITER Q = 10 DT burning plasma target. Primarily to reduce oxygen contamination in the limiter start-up phase, known to be a potential issue for current ramp-up on W surfaces, a conventional diborane-based glow discharge boronization system is included in the re-baseline. First-of-a-kind modelling of the boronization glow is used to provide the physics specification for this system. Erosion simulations accounting for the 3D wall geometry provide estimates both of the lifetime of boron (B) wall coatings and the subsequent B migration to remote areas, providing support to a simple evaluation which concludes that boronization, if it were to be used frequently, would dominate fuel retention in an all-W ITER. Boundary plasma (SOLPS-ITER) and integrated core–edge (JINTRAC) simulations, including W erosion and transport, clearly indicate the tendency for a self-regulating W sputter source in limiter configurations and highlight the importance of on-axis electron cyclotron power deposition to prevent W core accumulation in the early current ramp phase. These predicted trends are found experimentally in dedicated W limiter start-up experiments on the EAST tokamak. The SOLPS-ITER runs are used to formulate W source boundary conditions for 1.5D DINA code scenario design simulations which demonstrate that flattop durations of ∼100 s should be possible in hydrogen L-modes at nominal field and current (Ip = 15 MA, BT = 5.3 T) which are one of the principal SRO targets. Runaway electrons (RE) are considered to be a key threat to the integrity of the final, actively cooled FW panels. New simulations of RE deposition and subsequent thermal transport in W under conservative assumptions for the impact energy and spatial distribution, conclude that there is a strong argument to increase the W armour thickness in key FW areas to improve margins against cooling channel interface damage in the early DT operation phases when new RE seeds will be experienced for the first time.

Андрей Александрович Павлов, Михаил Анатольевич Коваленко, Виктор Антонович Гольдаде et al.

The electret properties and electrical conductivity of polypropylene-polyphenylene sulfide (PP-PPS) composites were studied. The results reveal that the effective surface charge density is higher in fibrous-porous materials (FPM) compared to film-based composites. In the electrical conductivity-temperature dependence, a characteristic up-turn is observed at a temperature of 110 °C, where the high-temperature segment of the curve corresponds to the intrinsic conductivity of the composite. The low-temperature segment can be attributed to structural defects. Additionally, two relaxation maxima are identified in the thermally stimulated depolarization (TSD) current spectra. The low-temperature peak is associated with the charge relaxation at the matrix-filler interface, a phenomenon driven by Maxwell — Wagner polarization. The high-temperature maxima are likely related to the relaxation of charges governed by the intrinsic conductivity of PP in its amorphous phase.

Biswajit Bera

Abstract Garhwal Himalaya is one of the most landslide-prone regions in the Himalayan Belt due to its seismo-tectonic background, geological complexity, climate, geomorphological setting and large-scale human interference. A gigantic rock avalanche happened on July 10, 2024, near Patalganga-Langsi Tunnel on the Badrinath Highway (NH-7) of the Chamoli district and disconnected the Joshimath, Badrinath, and Nanda Devi National Park for a few hours. This road corridor is a significant gateway for valued pilgrimage destinations and Indo-Tibet Border security. A detailed investigation has been done on the recent reactivated rock cum debris avalanche at the Patalganga-Langsi Tunnel site. The Artificial Neural Network (ANN) model identifies this area as a high landslide susceptible zone, and the entire Patalganga-Langsi is tectonically controlled by the Main Central Thrust (MCT) and other proximity minor thrusts. Rainfall and exposed slope conditions are the primary triggering factors behind this rock avalanche, and geologically, this slope is still vulnerable as the Factor of Safety (FoS) is near the threshold value (1.019). Subsequently, the Schmidt hammer rebound test showed poor rock strength (approximately 30 or sometimes below 30), and the rocks have numerous structural signatures, which make them more vulnerable. Results of kinematic analysis for the two studied road cut slopes (Slope 1 and 2) emphasized a tendency to wedge failure. After the geo-technical study and the hazard potential of the slide site, sustainable geo-environmental management techniques should be immediately executed to maintain the socio-economic lifeline as well as Indo-Tibetan Border security management. Geo-technical parameters of the Patalganga-Langsi site reflect that there is a very high probability of wedge-type rockfall and rock-cum-debris fall.

Jian Gu, Jun Huang, Jun Cheng

Understanding how the electronic structure of electrodes influences electrocatalytic reactions has been a longstanding topic in the electrochemistry community, with predominant attention paid to metallic electrodes. In this work, we present a defect physics perspective on the effect of semiconductor band structure on electrochemical redox reactions. Specifically, the Haldane-Anderson model, originally developed to study multiple charge states of transition-metal defects in semiconductors, is extended to describe electrochemical redox reactions by incorporating the solvent effect, inspired by the Holstein model. The solvent coordinate and the actual charge on the redox species in reduced and oxidized states are assumed to be instant equilibrium, and the transitions between these states are defined by the framework of Green's function. With these treatments, we treat the charge state transition in a self-consistent manner. We first confirm that this self-consistent approach is essential to accurately depict the hybridization effect of band structure by comparing the model-calculated ionization potential (IP), electron affinity (EA), and redox potential of the species with those obtained from density functional theory (DFT) calculations. Next, we illustrate how this self-consistent treatment enhances our understanding of the catalytic activities of semiconductor electrodes and the source of asymmetry in reorganization energies, which is often observed in prior ab initio molecular dynamics (AIMD) simulations. Additionally, we discuss how band structure impacts redox reactions in the strong coupling limit. Finally, we compare our work with other relevant studies in the literature.

J. C. Slater

Zhengyuan Yao, Gunhean Chong, Haixin Guo

Plant-based waste biomass with lignocellulose as an important component is produced in large quantities worldwide every year. The components of lignocellulose that typically exhibit high utilization value include cellulose and hemicellulose, as well as pentoses and hexoses derived from their hydrolysis. As a pretreatment for the hydrolysis process, delignification is a pivotal step to enhance cellulose/hemicellulose accessibility and achieve high yields of fermentable sugars. Additionally, deep eutectic solvents (DESs) are the most widely used solvents for delignification during biomass fractionation due to their clean and environmentally friendly attributes. DESs dissolve lignin by inducing a large amount of β-O-4 bond cleavage and partial carbon–carbon bond cleavage, retaining cellulose in the solid residue, while most of the hemicellulose is hydrolyzed in DES pretreatment. This article provides a comprehensive review of the influence of DESs in the lignocellulose separation process. Key factors such as lignin removal rate, sugar conversion rate, and product chemical structure are critically reviewed to assess the feasibility of employing DESs for lignocellulose separation.

J. Hasted

Qu Cao, Liang Zhang

Abstract In this paper, we generalize the Nguyen–Spradlin–Volovich–Wen (NSVW) tree formula from the MHV sector to any helicity sector. We find a close connection between the Permutohedron and the KLT relation, and construct a non-trivial mapping between them, linking the amplitudes in the gauge and gravity theories. The gravity amplitude can also be mapped from a determinant followed from the matrix-tree theorem. Besides, we use the binary tree graphs to manifest its Lie structure. In our tree formula, there is an evident Hopf algebra of the permutation group behind the gravity amplitudes. Using the tree formula, we can directly re-derive the soft/collinear limit of the amplitudes.

Awwab Qasim Jumaah Althahab, Branislav Vuksanovic, Mohamed Al-Mosawi et al.

Intensive care units (ICUs) are busy and noisy areas where patients and professional staff can be exposed to acoustic noise for long periods of time. In many cases, noise levels significantly exceed the levels recommended by the official health organisations. This situation can affect not only patient recovery but also professional staff, making ICUs unhealthy work and treatment environments. To introduce the measures and reduce the acoustic noise in the ICU, acoustic noise levels should first be measured and then appropriately analysed. However, in most studies dealing with this problem, measurements have been performed manually over short periods, leading to limited data being collected. They are usually followed by insufficient analysis, which in turn results in inadequate measures and noise reduction. This paper reviews recent works dealing with the problem of excessively high noise levels in ICUs and proposes a more thorough analysis of measured data both in the time and frequency domains. Applied frequency domain analysis identifies the cyclic behaviour of the measured sound pressure levels (SPLs) and detects the dominant frequency components in the SPL time series. Moreover, statistical analyses are produced to depict the patterns and SPLs to which patients in ICUs are typically exposed during their stay in the ICU. It has been shown that the acoustic environment is very similar every night, while it can vary significantly during the day or evening periods. However, during most of the observed time, recorded SPLs were significantly above the prescribed values, indicating an urgent need for their control and reduction. To effectively tackle this problem, more detailed information about the nature of noise during each of the analysed periods of the day is needed. This issue will be addressed in the continuation of this project.

Sergey A. Khaibrakhmanov, Alexander E. Dudorov, Anton I. Vasyunin et al.

The vertical structure of the accretion disks of young stars with fossil large-scale magnetic field is studied. The equations of magnetostatic equilibrium of the disk are solved taking into account the stellar gravity, gas and magnetic pressure, turbulent heating, and heating by stellar radiation. The modelled physical structure of the disk is used to simulate its chemical structure, in particular, to study the spatial distribution of CN molecules. The disk of the typical T Tauri star is considered. Simulations show that the temperature within the disk in the region $r<50$ au decreases with height and density profiles are steeper than in the isothermal case. Outside the `dead' zone, vertical profiles of the azimuthal component of the magnetic field are nonmonotonic, and the magnetic field strength maximum is reached within the disk. The magnetic pressure gradient can cause an increase in the disk thickness in comparison with the hydrostatic one. The CN molecule concentration is maximum near the photosphere and in the disk atmosphere where the magnetic field strength at chosen parameters is $\sim 0.01$ G. Measurements of the Zeeman splitting of CN lines in the submm range can be used to determine the magnetic field strength in these regions of accretion disks.

E. Wigner

C. W. Nooitgedacht, H. J. L. van der Lubbe, M. Ziegler et al.

Abstract Biogenic and inorganic calcium carbonates contain considerable amounts of internal water, both as free and organically associated water. The oxygen isotopic compositions (δ18O) of internal water and hosting carbonate are analyzed for various carbonates before and after heating at 175°C for 90 minutes. During heating, the δ18O values of internal water significantly increased in biogenic aragonites and speleothem calcite, whereas the δ18O carbonate values were lowered. Correspondingly, an aragonitic bivalve’s clumped‐isotope distribution (Δ47) changed during heating, increasing reconstructed paleotemperatures. In contrast, an inorganic aragonite crystal, containing a comparable amount of internal water, showed no oxygen isotope exchange, and its Δ47 values remained unaltered during heating, implying that there is a link between internal oxygen isotope exchange and Δ47 resetting. This alteration process occurred without any detectable transformation from aragonite to calcite. Our results therefore reveal a mechanism that facilitates oxygen isotope exchange between biogenic aragonite and its internal water, while simultaneously resetting the Δ47 values, without affecting mineralogy. Future studies may therefore apply coupled water‐carbonate analyses to scrutinize these kinds of diagenetic alteration processes. It appears that in biogenic aragonites, more carbonate is available for exchange reactions with the internal water reservoir than in inorganic aragonites, a feature that can be attributed to the distribution of organic‐associated water and/or high surface area fluid inclusions. This water‐aragonite exchange occurs at lower temperatures than those required for solid‐state bond reordering at the same timescale, and thus likely has occurred earlier during the burial of biogenic aragonites.

Xiaojiao Chen, Xiuqing Zhang, Mi Dong et al.

The prediction of wind power plays an indispensable role in maintaining the stability of the entire power grid. In this paper, a deep learning approach is proposed for the power prediction of multiple wind turbines. Starting from the time series of wind power, it is present a two-stage modeling strategy, in which a deep neural network combines spatiotemporal correlation to simultaneously predict the power of multiple wind turbines. Specifically, the network is a joint model composed of Long Short-Term Memory Network (LSTM) and Convolutional Neural Network (CNN). Herein, the LSTM captures the temporal dependence of the historical power sequence, while the CNN extracts the spatial features among the data, thereby achieving the power prediction for multiple wind turbines. The proposed approach is validated by using the wind power data from an offshore wind farm in China, and the results in comparison with other approaches shows the high prediction preciseness achieved by the proposed approach.