Fluctuation Mechanism Research Articles

Flat-band enhanced antiferromagnetic fluctuations and superconductivity in pressurized CsCr3Sb5

The spin dynamics and electronic orders of the kagome system at different filling levels stand as an intriguing subject in condensed matter physics. By first-principles calculations and random phase approximation analyses, we investigate the spin fluctuations and superconducting instabilities in kagome phase of CsCr3Sb5 under high pressure. At the filling level slightly below the kagome flat bands, our calculations reveal strong antiferromagnetic spin fluctuations in CsCr3Sb5, together with a leading s±-wave and a competing (dxy, dx2−y2)-wave superconducting order. Unlike the general intuition that the flat bands are closely related to the ferromagnetic correlations, here we propose a sublattice-momentum-coupling-driven mechanism for the antiferromagnetic fluctuations enhanced from the unoccupied flat bands. The mechanism is generally applicable to kagome systems where the Fermi level intersects near the flat bands, offering a new perspective for future studies of geometrically frustrated systems.

Dialogue mechanisms between astrocytic and neuronal networks: A whole-brain modelling approach.

Astrocytes critically shape whole-brain structure and function by forming extensive gap junctional networks that intimately and actively interact with neurons. Despite their importance, existing computational models of whole-brain activity ignore the roles of astrocytes while primarily focusing on neurons. Addressing this oversight, we introduce a biophysical neural mass network model, designed to capture the dynamic interplay between astrocytes and neurons via glutamatergic and GABAergic transmission pathways. This network model proposes that neural dynamics are constrained by a two-layered structural network interconnecting both astrocytic and neuronal populations, allowing us to investigate astrocytes' modulatory influences on whole-brain activity and emerging functional connectivity patterns. By developing a simulation methodology, informed by bifurcation and multilayer network theories, we demonstrate that the dialogue between astrocytic and neuronal networks manifests over fast-slow fluctuation mechanisms as well as through phase-amplitude connectivity processes. The findings from our research represent a significant leap forward in the modeling of glial-neuronal collaboration, promising deeper insights into their collaborative roles across health and disease states.

Spatiotemporal correlation of wall pressure fluctuations generated in scramjet inlet

Wall pressure fluctuations in the scramjet inlet are a significant aerodynamic load that requires special consideration in aircraft structural design. This study focuses on understanding the physical essence behind these pressure fluctuations by conducting wind tunnel measurements to analyze their time-frequency and spatiotemporal correlation characteristics. The working condition of the scramjet inlet is assessed based on the observed wall pressure fluctuations. A relatively accurate disturbance velocity is calculated by using the phase-array technique and a statistical algorithm, which indicates that the two dominant oscillations responsible for the unsteady flow and significant pressure fluctuations in the unstarted inlet should correspond to the acoustic mode, as their propagation speed is equivalent to the speed of sound. Wall pressure fluctuations in time-space domain reveals the second oscillation originating from to the first oscillation at the inlet lip. A spatiotemporal correlation analysis is conducted to investigate the generation mechanism of wall pressure fluctuations by examining the direction of energy flow on both temporal and spatial scales. The started inlet is primarily influenced by localized random fluctuations, while the un-started inlet is predominantly affected by the overflow-induced acoustic modes.

Shock oscillation and fluctuation mechanisms of wall pressure on a V-shaped blunt leading edge

Shock oscillation and fluctuation mechanisms of wall pressure on a V-shaped blunt leading edge

TCAD-based investigation of 1/f noise in advanced 22 nm FDSOI MOSFETs

In this work, the mechanistic insights behind low-frequency noise (LFN) of the advanced ultrathin body and buried oxide fully depleted silicon-on-insulator based metal–oxide–semiconductor field effect transistor (MOSFET) are unveiled. The gate voltage-induced noise power spectral density (SVG) is inversely proportional to frequency f (i.e., SVG∝1/fγ, γ∼ 1 is the frequency exponent) for nMOSFET and pMOSFET. Detailed numerical simulations are performed and well calibrated to reported SVG vs f characteristics. Simulation results are consistent with the reported experimental observations. We demonstrate that LFN is caused by the charge carrier number fluctuation mechanism, which is originated by trapping and de-trapping of channel charge carriers via. bulk traps (from oxygen vacancies) in the hafnium dioxide (HfO2) layer, but not through traps at the silicon dioxide (SiO2)/channel interface. This work therefore explains the similar magnitude of SVG in both nMOSFET and pMOSFET observed experimentally and further suggests that oxygen vacancies inside gate oxides are critical to suppress the low-frequency noise in emerging high-k based MOSFETs.

Revealing the influence mechanism of pre-fermentation degree and storage temperature fluctuations on frozen steamed bread dough quality

This study investigated the effects of pre-fermentation degree and storage temperature fluctuations on the gas cells, gluten protein, rheological properties of frozen dough, and quality of steamed bread. Three pre-fermentation degrees and four fluctuating temperatures (-10°C, 0°C, 10°C, and 25°C) were used. The gas cell size increased with the pre-fermentation degree; however, the gas cells merged and ruptured during temperature fluctuations. Sodium dodecyl sulfate extraction protein content and free sulfhydryl content increased by 3.07% and 33.62%, respectively, in the medium pre-fermentation group at 25°C compared with those at -10°C. The maximum strain of dough increased as pre-fermentation degree and fluctuating temperatures increased. The specific volumes of steamed bread with medium pre-fermentation degree were 1.87mL/g at -10°C and 1.47mL/g at 25°C. In conclusion, higher temperature fluctuations exceeding the freezing point exacerbated the dough and steamed bread quality, particularly in high pre-fermentation degree dough.

Collective behavior in proton number fluctuations seen in [formula omitted] 2.4 GeV Au+Au collisions

Collective behavior in proton number fluctuations seen in [formula omitted] 2.4 GeV Au+Au collisions

Refined Analysis of the Correlated Carrier Number and Mobility Fluctuations Mechanism in MOSFETs

Refined Analysis of the Correlated Carrier Number and Mobility Fluctuations Mechanism in MOSFETs

Natural width of the superconducting transition in epitaxial TiN films

AbstractWe investigate the effect of various fluctuation mechanisms on the DC resistance in superconducting (SC) devices based on epitaxial titanium nitride (TiN) films. The samples we studied show a relatively steep resistive transition (RT), with a transition widthΔT/Tc∼0.002−0.025, depending on the film thickness (20 nm, 9 nm, and 5 nm) and device dimensions. This value is significantly broader than expected due to conventional SC fluctuations (ΔT/Tc≪10−3). The shape and width of the RT can be perfectly described by the well-known effective medium theory, which allows us to understand the origin of the inhomogeneity in the SC properties of TiN films. We propose that this inhomogeneity can have both dynamic and static origins. The dynamic mechanism is associated with spontaneous fluctuations in electron temperature (T-fluctuations), while the static mechanism is due to a random spatial distribution of surface magnetic disorder (MD). Our analysis has revealed clear correlations between the transition width and material parameters as well as device size for both proposed mechanisms. While T-fluctuations may contribute significantly to the observed transition width, our findings suggest that the dominant contribution comes from the MD mechanism. Our results provide new insights into the microscopic origin of broadening of the SC transition and inhomogeneity in thin SC films.

Investigation on room-temperature persistent photoconductivity in γ-InSe layered semiconductor

Investigation on room-temperature persistent photoconductivity in γ-InSe layered semiconductor

Streamflow diurnal fluctuation and driving mechanism of headwater stream in a semi-humid mountainous region

Streamflow diurnal fluctuation and driving mechanism of headwater stream in a semi-humid mountainous region

The randomness and determinacy of wall pressure fluctuations in incompressible flow

Wall pressure fluctuations caused by turbulent boundary layers have a significant impact on aircraft structural vibration and cabin noise. This study aims to investigate the mechanism of turbulence-induced pressure fluctuations by focusing on the randomness of wall pressure fluctuations, analyzed in both the time–frequency and spatial-wavenumber domains using measured data obtained from a phase array in a wind tunnel. Three roughness elements were designed and installed upstream of the plate to manipulate the turbulent boundary layer at a specific Mach number. The results of the investigation demonstrate that the disturbance strength induced by the roughness element influences the randomness of wall pressure fluctuations, in addition to the parameters utilized for data analysis. Generally, stronger turbulence fluctuations tend to decrease the randomness of pressure fluctuations. Moreover, wall pressure fluctuations also exhibit certain statistical principles that cannot be precisely calculated using mathematical expressions, highlighting their inherent randomness. Further investigation into randomness in the spatial-wavenumber domain revealed the hydrodynamic modes of turbulence fluctuations with varying convection velocity analyzed through wavenumber maps computed using the beamforming algorithm. These modes with variable convective speed significantly contribute to the generation of randomness in wall pressure fluctuations. Both the time–frequency domain and the spatial-wavenumber domain affect the randomness characteristics of wall pressure fluctuations. However, such effects are not easily discernible through a rudimentary analysis of the space–time correlation of turbulence fluctuations.

A study of expansion force propagation characteristics and early warning feasibility for the thermal diffusion process of lithium-ion battery modules

A study of expansion force propagation characteristics and early warning feasibility for the thermal diffusion process of lithium-ion battery modules

Experimental study on the influence of the riser on the gas-liquid flow in the horizontal pipeline of the offshore pipeline-riser system

Experimental study on the influence of the riser on the gas-liquid flow in the horizontal pipeline of the offshore pipeline-riser system

Population Fluctuation Mechanism of the Super‐Thermal Photon Statistic of Quantum LEDs with Collective Effects

AbstractThe analytical procedure is developed for the calculation of the quantum second‐order autocorrelation function of a small super‐radiant LED, where the field, polarisation, and population of the active medium cannot be eliminated adiabatically. The Langevin force, which describes the effect of population fluctuations on the LED polarisation and preserves the operator commutation relations, is found. It is demonstrated that the super‐thermal photon statistics with of a small quantum LED with large photon number fluctuations, emitter‐field coupling, bad cavity, and operating in the limit , is the result of a combined effect of the spontaneous emission, collective effects and population fluctuations. Analytical expressions for and are derived.

Entropy Theory in the Context of Physics Education

Entropy, initially a concept in thermodynamics describing the degree of disorder in a system, has been extended to information theory and non-equilibrium thermodynamics. The article proposes that the physical classroom teaching system can be viewed as a dissipative structure, promoting the orderly development of students' cognition through openness, non-equilibrium states, and fluctuation mechanisms. Specific strategies include opening up teaching content and methods, creating non-equilibrium state experiments, introducing cognitive fluctuations, and utilizing non-linear effects. These approaches help to stimulate students' desire for knowledge, optimize the teaching process, and achieve efficient physical classroom teaching.

Analysis and Modeling of Intermittent Fluctuation Mechanisms of Piezoelectric Impact-Induced Vibration Cantilever Energy Harvester

Analysis and Modeling of Intermittent Fluctuation Mechanisms of Piezoelectric Impact-Induced Vibration Cantilever Energy Harvester

A Study of Particle Acceleration in Blazar Jets

The particle acceleration of blazar jets is crucial to high-energy astrophysics, yet the acceleration mechanism division in blazar subclasses and the underlying nature of these mechanisms remain elusive. In this work, we utilized the synchrotron spectral information (synchrotron peak frequency, logνsy , and corresponding curvature, b sy) of 2705 blazars from the literature and studied the subject of particle acceleration in blazar jets by analyzing the correlation between logνsy and 1/b sy. Our results suggested that the entire sample follows an energy-dependent probability acceleration (EDPA). Specifically, the low inverse Compton peak sources (LCPs) follow the mechanism of fluctuations of fractional gain acceleration (FFGA), while the high inverse Compton peak sources (HCPs) follow an acceleration mechanism of EDPA. Our results indicated that the separation between LCPs and HCPs results from the electron peak Lorentz factor (γ p), and the differentiation should originate from different acceleration mechanisms. Moreover, our study revealed a transition in the acceleration mechanism from FFGA to EDPA around logνsy∼15 through a detailed analysis of binned- logνsy . The mechanism of FFGA dominates the particle acceleration in LCP jets because of stronger jets and the EDPA dominates the particle energy gain in the HCPs due to a more efficient acceleration process.

Experimental study on pressure fluctuation in header of nuclear power plant SEC system after long-term pump shutdown

Experimental study on pressure fluctuation in header of nuclear power plant SEC system after long-term pump shutdown

Charge fluctuations on the dust grains in the presence of energetic electrons

Abstract Dust charging is an arbitrary process occurring at random times which results in fluctuations of dust charge around its equilibrium value. To have a better insight into the mechanism of charge fluctuations, a numerical simulation of the statistical nature of the dust charging process is investigated. Here, a multicomponent non-Maxwellian hydrogen plasma comprising two electron groups, positive ions, and dust grains is modelled. An increase in the overall negative dust charge number is reported in the presence of non-Maxwellian electrons. Additionally, the study emphasizes the role of electron distribution and hot electron temperature and density on the charge fluctuations of the dust grains.