Fluctuation Model Research Articles

Surface and decay properties of newly synthesized 207,208Th isotopes for various α-decay chains

Considering various initial deformations, the ground, first excited, and second excited states binding energies are calculated using the effective field theory motivated relativistic mean-field based IOPB-I force parameter. The alpha decay chains for both the 207Th and 208Th are examined. As observed for both nuclei, it takes four subsequent α-particle emissions to reach the stable Pb nucleus. The half-lives determined by two widely used Viola-Seaborg and modified universal decay law formulas are compared with the available experimental data. The surface property-like symmetry energy is also predicted for these nuclei in the framework of the coherent density fluctuation model and establishes a connection between the decay behavior and the symmetry energy.

A Baseline Model of Behavioral Political Cycles and Macroeconomic Fluctuations

Although the rational choice approach remains the theoretical modeling paradigm in economics and political sciences, the relevance of behavioral factors such as heuristics and biases has been increasingly acknowledged in both fields over the last decades. Against this background, and in honor the lifetime work of Peter Flaschel, we set up a baseline political-macroeconomic model of the Keynes-Metzler-Goodwin (KMG) variety enhanced with endogenous political choices as in Di Guilmi and Galanis (2021). The mutual feedback between the political and the macroeconomic spheres, generated by our framework, gives rise to cyclical dynamics around moving long-term trends for certain parameter constellations. The results of both the stability analysis and the simulations illustrate the existence of multiple political equilibria in the presence of endogenous electoral presences resulting from the crucial role of income distribution not only as a determinant of aggregate investment and aggregate output, but also, of the political climate.

Dynamical Model for Power Grid Frequency Fluctuations: Application to Islands With High Penetration of Wind Generation

We study the effects of a high share of wind generation on the frequency fluctuations of power grids on islands. We propose a dynamical model that includes conventional and variable renewable generation, as well as demand variations. Our model can assimilate load and generation data and reproduce frequency fluctuations with the current power mix with a high degree of accuracy, and it allows to simulate the frequency dynamics for different scenarios with a very high penetration of renewable energy. As a case study, we analyze the power grid of Gran Canaria island. We characterize the frequency fluctuations and propose a method to estimate the control needed to keep frequency deviations within reasonable limits.

Compact Modeling of Process Variations in Nanosheet Complementary FET (CFET) and Circuit Performance Predictions

In this work, a semi-analytical compact model of random process fluctuations in nanosheet (NS) gate-all-around (GAA) complementary FET (CFET) is proposed, including work-function variation (WFV), line edge roughness (LER), and gate edge roughness (GER). Different from the conventional NS GAA FET, GER has a significantly different impact on NS GAA CFET, due to the additional p-type work-function (p-WF) liner for p-FET threshold voltage tuning as well as the common metal gate, and a negative correlation with p-WF thickness is introduced into GER model. The proposed model is embedded into Berkeley short-channel insulated-gate field-effect transistor model-common multi-gate (BSIM-CMG) to predict the device performance variability by HSPICE Monte Carlo (MC) simulations. Excellent agreement between stochastic TCAD and HSPICE MC simulations is demonstrated. The effect of process variations on the power-performance-area (PPA) of standard cells (SDCs) and ring oscillator (RO) circuit is predicted by the proposed model. Most of the process variations make a more than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 10% to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$+$</tex-math> </inline-formula> 20% change in power consumption in NOR2. WFV has the greatest impact on RO PPA, making a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 10% to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$+$</tex-math> </inline-formula> 12.3% change in power consumption. The proposed model provides a helpful guideline for the random variation-aware CFET circuit design and related technology process development.

On the Variability of In Situ Surface Layer Refractivity Measurements

Direct measurements of profiles of atmospheric properties near the ocean surface and within the marine atmospheric surface layer often contain a large degree of variability. The variability observed can be explained by numerous technical and natural reasons such as the temporal variability over the time span a profile is measured (unsteadiness in the mean), spatial variations (inhomogeneity), turbulent fluctuations, and measurement uncertainty. In this study, we explored the observed variability in vertical distributions of refractive index measured with a tethered-balloon-based marine atmospheric profiling system (MAPS). MAPS profiled the atmosphere from approximately 0.5 to 50 m, with instantaneous (order 1 s) measurements performed at each profiled altitude. To explore whether the observed scatter could be largely explained by (inertial-scale) turbulent fluctuations, we simulated refractive index fluctuations with a spectral-based turbulent refractive index fluctuation (TRIF) model. TRIF was optimized based on the MAPS measurements to determine a vertical length scale of the turbulence. The scales computed in the optimization were reasonable based on other estimates in the literature under similar conditions. However, finer-scale trends of the length scale with atmospheric stability did not match expectations, and thus the estimated length scales may be considered more as an order-of-magnitude estimate rather than an exact measurement of this scale. The ability to match the observed variability in the MAPS data using a turbulence model with a reasonable choice of vertical length scale suggests that the MAPS variability is dominated by physical processes such as turbulence rather than being primarily driven by measurement uncertainty.

Observation of interface trap reduction in fluoropolymer dielectric organic transistors by low-frequency noise spectroscopy

This study examines the low-frequency noise characteristics of the 2,7-dioctyl[1] benzothieno[3,2-b][1] benzothiophene organic thin-film transistor (OTFT) having a CYTOP dielectric layer. Specifically, the fabricated OTFT exhibits 1/f noise, and its behavior is explained via a carrier number fluctuation model. Additionally, the volume trap density (NT) of the gate dielectric is quantitatively evaluated and compared with its counterpart having SiO2 dielectric layer. The analysis of the results shows that the hydrophilic entities of the dielectric layer strongly influence the NT, while the CYTOP having hydrophobic properties provides less NT than that of SiO2.

Modeling of daily temperature fluctuations in the root layer of sandy forest soils

Modeling of daily temperature fluctuations in the root layer of sandy forest soils

1/f noise of short-channel indium tin oxide transistors under stress

In this work, we investigate the reliability and stability of short-channel indium tin oxide (ITO) field-effect transistors through 1/f noise characterization at elevated temperature with positive bias temperature instability (PBTI). The 1/f noise behavior of a short-channel 60-nm-long channel ITO transistor can be described by the carrier number fluctuation model, suggesting that carrier trapping and de-trapping by trap states within the 5 nm thin high-κ HfLaO dielectric are the dominant mechanisms affecting 1/f noise. Small positive threshold voltage shifts of 0.042 and 0.057 V after PBTI measurements of 3000 s at 25 and 85 °C have been obtained, respectively. The higher gate leakage current at elevated temperature leads to an earlier breakdown in the time-dependent dielectric breakdown measurement. Furthermore, 1/f noise after PBTI has also been carried out at elevated temperature, and the degradations after stress can also be attributed to the stress induced traps inside the gate dielectric.

Watertable fluctuations in coastal unconfined aquifers with a sloping sea boundary: Vertical flow and dynamic effective porosity effects

Interactions between the tide and sloping sea boundary make watertable fluctuations in coastal unconfined aquifers complicated. Based on a perturbation method, we derived a new analytical solution to predict watertable fluctuations for coastal unconfined aquifers with a sloping sea boundary. Following validation with a numerical model, the analytical solution was used to explore the effects of the vertical flow (in the saturated zone) and dynamic effective porosity on watertable fluctuations. Results show that the new analytical solution accurately predicts watertable fluctuations for coastal unconfined aquifers with a sloping sea boundary. Compared with sand coastal unconfined aquifers, both vertical flow and dynamic effective porosity effects on watertable fluctuations are more pronounced for loam coastal unconfined aquifers. Vertical flow has a minor influence on the fluctuation amplitude while it significantly decreases the phase lag of the watertable fluctuation at a given location. In contrast to vertical flow, accounting for the dynamic effective porosity not only decreases the phase lag, but also significantly amplifies the fluctuation amplitude for a given location, which enables watertable wave propagation further inland. Increasing the beach slope weakens the effects of the vertical flow and dynamic effective porosity on watertable fluctuations. Furthermore, including either the vertical flow or dynamic effective porosity effects leads to a lower watertable overheight. These results highlight the importance of vertical flow and dynamic effective porosity effects in models of watertable fluctuations.

Investigation of the Effect of Disorder on the Tauc Edge of Hydrogenated Amorphous Silicon Using Dunstan’s Bandgap Fluctuations Model

The optical absorption edge in both Urbach and Tauc regions are analyzed for hydrogenated amorphous silicon optical data of Cody et al and Viturro and Weiser . Dunstan’s model, introduces disorder into the band-band absorption through a linear exponential distribution of local energy gaps. This model has a simple mathematical form and has a clear physical meaning in comparison to the somewhat similar models of O’Leary and Guerra, yet Dunstan’s model is unjustly neglected in literature. The most important physical parameter of the model is the energy gap parameter- Eo, which represents the separation between the valence and conduction band edges, it can be considered as the mobility gap of the material. Dunstan’s model is found successful in capturing the optical data of Cody et al and, Viturro and Weiser. A plot of the energy parameters of the Dunstan and Cody models, Eo against Eopt respectively, was proposed here to separate the masking contribution of tail-related absorption from the real change of the band gap, and was found fruitful for this purpose. This is because Eo is a function only of the separation between valence and conduction band edges, while the meaning of the optical energy Eopt is ambiguous because it is also a function of absorption due to tail-related absorption that results from disorder. This simple plot of Eo vs. Eopt , through the slope ΔEo/ΔEopt of the fitting straight line , was capable of distinguishing the different relative contributions of disorder between Cody et al and Viturro and Weiser optical data, Eo value was found less sensitive to hydrogen content variation for Viturro and Weiser data which is interpreted due to their better control of the thin film deposition process. Keywords: optical energy gap, absorption coefficient, amorphous semiconductor, mobility gap

Complex Monte Carlo Light-Driven Dynamics of Monomers in Functionalized Bond Fluctuation Model Polymer Chains.

We study Monte Carlo dynamics of the monomers and center of mass of a model polymer chain functionalized with azobenzene molecules in the presence of an inhomogeneous linearly polarized laser light. The simulations use a generalized Bond Fluctuation Model. The mean squared displacements of the monomers and the center of mass are analyzed in a period of Monte Carlo time typical for a build-up of Surface Relief Grating. Approximate scaling laws for mean squared displacements are found and interpreted in terms of sub- and superdiffusive dynamics for the monomers and center of mass. A counterintuitive effect is observed, where the monomers perform subdiffusive motion but the resulting motion of the center of mass is superdiffusive. This result disparages theoretical approaches based on an assumption that the dynamics of single monomers in a chain can be characterized in terms of independent identically distributed random variables.

The Bielefeld School of economics, Post Keynesian economics, and dynamic complexity

The Bielefeld School of economics emerged in the 1990s, led by economists located at/or regularly visiting the University of Bielefeld in that period and the following decades, with Peter Flaschel as arguably its central leading figure based at that university. This school drew especially on the work of Richard Goodwin and his nonlinear dynamical models of macroeconomic growth and fluctuations. His work, in turn, drew on both Keynes and Marx as well as Schumpeter. Besides these influences, the school would also eventually add inventory adjustment models due to Lloyd Metzler to model endogenous fluctuations with associated income distribution dynamics with economic growth. While drawing on both classical and Keynesian sources, these models differ from modern New Keynesian models by eschewing rational expectations as well as equilibrium, emphasizing instead ongoing disequilibrium adjustment. While they have some similarities to Post Keynesian models, there has been relatively little interchange or interaction between the two schools. Several in the Bielefeld group appeared to be sometimes critical of Post Keynesians for a perceived lack of rigor in a number of their models. At the same time though there are several sub-schools of Post Keynesian economics similar to the Bielefeld School in approach than others. Probably the clearest area of overlap and similarity involves models exhibiting dynamic complexity, irregular endogenous fluctuations. Indeed one Post Keynesian tradition derives from nonlinear dynamical models due to Kaldor, which resemble those of Goodwin, the main foundation for the Bielefeld School models.

Generalized parton distributions of sea quark at zero skewness in the light-cone model

We study the chiral-even generalized parton distributions (GPDs) of {bar{u}} and {bar{d}} quarks at zero skewness using the overlap representation within the light cone formalism. The GPDs of {bar{u}} and {bar{d}} quarks can be expressed as the convolution of the light cone wave functions which are obtained from the baryon-meson fluctuation model in terms of the |q{bar{q}}Brangle Fock states. We present the numerical results for H^{{bar{u}}/P}(x,xi ,Delta ^2), H^{{bar{d}}/P}(x,xi ,Delta ^2), E^{{bar{u}}/P}(x,xi ,Delta ^2) and E^{{bar{d}}/P}(x,xi ,Delta ^2). We apply the model resulting GPDs to calculate the orbital angular momentum of the {bar{u}} and {bar{d}} quarks, showing that L^{{bar{u}}/P}, L^{{bar{d}}/P} are positive and L^{{bar{u}}/P} is smaller than L^{{bar{d}}/P}. The sea quark OAM distributions in the impact parameter space L_{{bar{q}}}(x,{varvec{b}}_{varvec{T}}) are also calculated.

Low-frequency noise in quasi-ballistic monolithic Al–Ge–Al nanowire field effect transistors

In this work, Al2O3-passivated, monolithic, and crystalline Al–Ge–Al heterostructure nanowire field effect transistors (FETs) with Ge channel lengths ranging from 18 to 826 nm are analyzed from a low-frequency noise perspective. 1/f and random telegraph noise (RTN) are analyzed in an accumulation mode, where the hole channel is formed by applying a back-gate potential VG. The normalized power spectral density of drain current fluctuations of 1/f noise (SID/ID2) at medium currents follows nearly an 1/ID trend. 1/f noise is analyzed within both the mobility and carrier number fluctuation models (MFM and CNFM), respectively. Taking the MFM into account, the Hooge noise parameter α spreads in the interval of 1.5 × 10−4 to 4 × 10−2, with lower values for shorter devices. Using the same data and the CNFM, the density of interface states Dit in the Al2O3/GexOy/Ge system was estimated using the transconductance extracted from the quasi-static transfer I/V characteristics. The extracted Dit values range from 5 × 109 to 3 × 1012 cm−2 eV−1. Contact noise has also been observed in some devices at high currents. RTN analyzed in time domain exhibits a relative RTN amplitude in the 0.3%–20% range. Capture and emission time constants as a function of VG exhibit a typical behavior for metal oxide semiconductor FETs. The extracted noise parameters are comparable with Ge and III–V nanodevices of top-down and bottom-up technologies.

SCOPF considering voltage and power fluctuation under renewable energy integration

Security-Constrained Optimal Power Flow (SCOPF) method could generate system optimal operation point, which guarantee system security by avoiding any overload whenever expected N-1 contingencies occurred. However, renewable power integration increases uncertainty of system security, which is not well treated in conventional SCOPF model. Then this study proposes an improved SCOPF model, which aims at optimizing outputs of generators to increasing security of system facing challenges by N-1 contingencies accompanied by renewable power fluctuations. Semi-invariant is employed to express the stochastic behavior of wind and photovoltaic power generation. Considering the influence of transformer transformation ratio on admittance matrix, the uncertainty of injected renewable power is combined with the adjustable characteristics of network parameters to obtain the fluctuation model of branch power and bus voltage. Therefore, the constraints for SCOPF are restated to treat the problem that expected value based traditional model makes errors to confirm overload. The probability analysis for branch overload allows this study to present a potential reduced contingency set, in which small-probability events are rationally excluded. Thus, the constraint quantities as well as the complexity of the optimization problem are effectively reduced to decrease the computation burden. A Benders decomposition method based interior point approach is used to solve the improved SCOPF optimization model. Case studies based on IEEE39 bus system demonstrate the efficiency of proposed method.

Magnetic-field-induced valence change in Eu(Co1−xNix)2P2 up to 60 T

The solid solution 122 compounds, $\mathrm{Eu}{({\mathrm{Co}}_{1\ensuremath{-}x}{\mathrm{Ni}}_{x})}_{2}{\mathrm{P}}_{2}$, show a valence transition between divalent state and intermediate valence states at Eu, which is firmly correlated to multiple degrees of freedom in the solid such as the isostructural transition between the collapsed tetragonal (cT) and uncollapsed tetragonal (ucT) structures, $3d$ magnetism, and the formation of P-P dimers. To gain insights into the correlated behavior, we investigate the effect of high magnetic fields on the samples of $x=0.4$ and 0.5 using magnetostriction and magnetization measurements up to 60 T. The samples are in the Eu valence-fluctuating regime, where the possible structural transition from cT to ucT may be induced by the Eu valence change under the magnetic fields. For both samples, magnetostriction smoothly increases with increasing magnetic fields. The behavior is in good agreement with the calculated results using the interconfigurational fluctuation (ICF) model that describes the Eu valence change. This indicates that $\mathrm{\ensuremath{\Delta}}L$ represents the change of the Eu valence state in these compounds. Magnetization curves for both compounds show good agreement with the ICF model at high magnetic fields. In contrast, in the low-magnetic-field region, magnetization curves do not agree with the ICF model. These results indicate that the Eu valence changes manifest themselves in the magnetization curves at high magnetic fields and that the magnetism of the $3d$ electrons manifests itself in the magnetization at low magnetic fields. Hence, we conclude that the valence change occurs within the Eu valence fluctuation regime coupled with the cT structure. Thereby, we believe that the transition to ucT structure, which is firmly coupled with the divalent Eu state, does not occur within the magnetic field range of the present study. Even higher magnetic fields or pulsed magnetic fields with slower pulse durations may induce such large state changes in the present material, which is triggered by the Eu valence change under high magnetic fields.

Universality of trap-induced mobility fluctuations between 1/f noise and random telegraph noise in nanoscale FD-SOI MOSFETs

Low frequency noise (LFN) and random telegraph noise (RTN) are investigated statistically on nanoscale MOSFETs of 28 nm fully depleted silicon-on-insulator technology. The analysis reveals that the mean noise level is well described by the carrier number fluctuations with a correlated mobility fluctuations model. As for the RTN, it is shown that the mean amplitude of signals is driven by correlated mobility fluctuations in strong inversion. The comparison between the extracted parameters of the LFN and RTN analysis demonstrates that the remote Coulomb scattering impact due to the trapped and detrapped charges remains the same on average for this technology, whether it is the average noise spectrum of all devices or the average amplitude of the detected RTN signals.

Low-Frequency Noise of 4H-SiC CMOS Technology for Analog ICs

To design low-noise analog ICs for nuclear power plants, low-frequency noise (LFN) of 4H-SiC CMOS technology was studied in the frequency range of 3 Hz–10 kHz at room temperature. The LFN of the long-channel MOS devices was systematically studied in terms of gate length, gate width, drain current, and drain voltage. It was found to follow the noise model for carrier number fluctuation regardless of conduction type. In addition, the standard deviation of spectral noise density ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}_{\text {id}}$ </tex-math></inline-formula> ) at 10 Hz for the p-channel MOS was experimentally found to be <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.6\times $ </tex-math></inline-formula> larger than that for the n-channel MOS. This was caused by the increase in random telegraph noise (RTN) caused by oxide hole traps with nitrogen incorporation at the SiO2/SiC interface. The flicker noise coefficient (KF) in the noise model was estimated to be <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${4.1} \times {10}^{-{26}}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${1.2} \times {10}^{-{27}}\,\,\text{s}^{\text {1-EF}}\text{A}^{\text {2-AF}}\text{F}^{^{^{^{}}}}$ </tex-math></inline-formula> for the n- and p-channel MOS, respectively.

Abnormal Electromagnetic Wave Detection Method Before Earthquake Based on Feature Extraction of Radio Frequency I/Q Signal

Earthquake is one of the more common natural disasters. At present, it is mainly through the deployment of monitoring stations to provide the earthquake information broadcasting service. Earthquakes are caused by the Earth’s plates pushing against each other. Before an earthquake occurs, the energy gathered by plate compression will produce abnormal electromagnetic radiation due to the compression magnetic effect. The energy detection method of abnormal electromagnetic radiation has been proposed by researchers for a long time. Anomalous electromagnetic radiation is difficult to catch because its energy is very weak. Based on the distributed electromagnetic spectrum detection method, this paper proposes the original radio frequency (RF) I/Q sample data. Combined with I/Q component cumulative distance fluctuation estimation method, abnormal electromagnetic radiation phenomenon is detected. Combined with source location information, magnitude and depth, a prediction model of cumulative distance fluctuation of I/Q component is proposed based on the RF I/Q sample data of electromagnetic spectrum. The results of actual monitoring data show that the prediction model of I/Q component cumulative distance fluctuation estimation can accurately describe the abnormal electromagnetic radiation phenomenon generated by earthquake information above magnitude 6. Combined with a large-scale distributed electromagnetic spectrum detection system, an earthquake prediction system with higher accuracy can be realized.

Mathematical modeling of pulsations in the drillingfluid

Purpose. To improve the efficiency of cleaning wells from drilled rock by using a pulsating flow of drilling fluid. to study the effect of cuttings concentration and distance from the pulse source on the parameters of its oscillations. The methods. Based on the analysis of the peculiarities of the well flushing process, the possibility of using an uneven flow of drilling mud created by fluid pressure fluctuations at the bottom of the well mathematical modeling of fluctuations in the two-phase environment of the flow of drilling fluid with drilled rock was carried out. In order to construct a mathematical model of oscillatory vibrations, the initial and boundary conditions for solving the homogeneous wave equation of the third order are set. The solution of this equation is realized using the Fourier method. Based on the results of the analytical calculations, a program in the JavaScript environment was developed to study the effect of cuttings concentration and distance from the pulse source on the vibration parameters. Findings. Using the developed program, the dependence of the change in the intrinsic vibration displacement of a two-phase medium on time was investigated when the cuttings concentration varies from 0 to 13 % in the drilling fluid and the distance from the pulse source varies from 1 to 1000 m. It was found that the vibration displacement in time is a sinusoidal curve with a certain period. It was found that the pulsation frequency decreases in hyperbolic dependence with distance from the pulse source due to attenuation in a two-phase medium. It was found that pulsations propagate effectively at a distance of up to 300 m from the pulse source. The effect of the cuttings concentration in the drilling fluid on the pulsation frequency is investigated. The originality. A mathematical model of the process of rock particles removal through the annular space of the well by a pulsating flow of drilling fluid is created. Practical implementation. Software has been developed to assess the effect of cuttings concentration and distance from the pulse source on the oscillation parameters, which will allow to evaluate and improve the process of well cleaning with a pulsating flow of drilling fluid.