More about solar g modes

Context. The detection of asymptotic solar g-mode parameters was the main goal of the GOLF instrument onboard the SOHO space observatory. This detection has recently been reported and has identified a rapid mean rotation of the solar core, with a one-week period, nearly four times faster than all the rest of the solar body, from the surface to the bottom of the radiative zone. Aim. We present here the detection of more g modes of higher degree, and a more precise estimation of all their parameters, which will have to be exploited as additional constraints in modeling the solar core. Methods. Having identified the period equidistance and the splitting of a large number of asymptotic g modes of degrees 1 and 2, we test a model of frequencies of these modes by a cross-correlation with the power spectrum from which they have been detected. It shows a high correlation peak at lag zero, showing that the model is hidden but present in the real spectrum. The model parameters can then be adjusted to optimize the position (at exactly zero lag) and the height of this correlation peak. The same method is then extended to the search for modes of degrees 3 and 4, which were not detected in the previous analysis.Results. g-mode parameters are optimally measured in similar-frequency bandwidths, ranging from 7 to 8 μHz at one end and all close to 30 μHz at the other end, for the degrees 1 to 4. They include the four asymptotic period equidistances, the slight departure from equidistance of the detected periods for l = 1 and l = 2, the measured amplitudes, functions of the degree and the tesseral order, and the splittings that will possibly constrain the estimated sharpness of the transition between the one-week mean rotation of the core and the almost four-week rotation of the radiative envelope. The g-mode periods themselves are crucial inputs in the solar core structure helioseismic investigation.

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Linkages between Energy Delivery and Economic Growth from the Point of View of Sustainable Development and Seaports

Energies ◽

10.3390/en14144255 ◽

2021 ◽

Vol 14 (14) ◽

pp. 4255

Author(s):

Elżbieta Szaruga ◽

Zuzanna Kłos-Adamkiewicz ◽

Agnieszka Gozdek ◽

Elżbieta Załoga

Keyword(s):

Sustainable Development ◽

Crude Oil ◽

Cross Correlation ◽

Point Of View ◽

Oil Products ◽

Modern Approach ◽

Economic Cycles ◽

Study Results ◽

The One ◽

Oil And Oil Products

This paper presents the synchronisation of economic cycles of GDP and crude oil and oil products cargo volumes in major Polish seaports. On the one hand, this issue fits into the concept of sustainable development including decoupling; on the other hand, the synchronisation may be an early warning tool. Crude oil and oil products cargo volumes are a specific barometer that predicts the next economic cycle, especially as they are primary sources of energy production. The research study applies a number of TRAMO/SEATS methods, the Hodrick–Prescott filter, spectral analysis, correlation and cross-correlation function. Noteworthy is the modern approach of using synchronisation of economic cycles as a tool, which was described in the paper. According to the study results, the cyclical components of the cargo traffic and GDP were affected by the leakage of other short-term cycles. However, based on the cross-correlation, it was proved that changes in crude oil and oil products cargo volumes preceded changes in GDP by 1–3 quarters, which may be valuable information for decision-makers and economic development planners.

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Global Sensitivity Analysis of a Homogenized Constrained Mixture Model of Arterial Growth and Remodeling

Journal of Elasticity ◽

10.1007/s10659-021-09833-9 ◽

2021 ◽

Author(s):

Sebastian Brandstaeter ◽

Sebastian L. Fuchs ◽

Jonas Biehler ◽

Roland C. Aydin ◽

Wolfgang A. Wall ◽

...

Keyword(s):

Sensitivity Analysis ◽

Global Sensitivity Analysis ◽

Model Parameters ◽

Computational Studies ◽

Growth And Remodeling ◽

Global Sensitivity ◽

Output Variability ◽

Constrained Mixture ◽

The One ◽

Influential Parameters

AbstractGrowth and remodeling in arterial tissue have attracted considerable attention over the last decade. Mathematical models have been proposed, and computational studies with these have helped to understand the role of the different model parameters. So far it remains, however, poorly understood how much of the model output variability can be attributed to the individual input parameters and their interactions. To clarify this, we propose herein a global sensitivity analysis, based on Sobol indices, for a homogenized constrained mixture model of aortic growth and remodeling. In two representative examples, we found that 54–80% of the long term output variability resulted from only three model parameters. In our study, the two most influential parameters were the one characterizing the ability of the tissue to increase collagen production under increased stress and the one characterizing the collagen half-life time. The third most influential parameter was the one characterizing the strain-stiffening of collagen under large deformation. Our results suggest that in future computational studies it may - at least in scenarios similar to the ones studied herein - suffice to use population average values for the other parameters. Moreover, our results suggest that developing methods to measure the said three most influential parameters may be an important step towards reliable patient-specific predictions of the enlargement of abdominal aortic aneurysms in clinical practice.

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Detection and Localization for Multiple Stationary Human Targets Based on Cross-Correlation of Dual-Station SFCW Radars

Remote Sensing ◽

10.3390/rs11121428 ◽

2019 ◽

Vol 11 (12) ◽

pp. 1428 ◽

Cited By ~ 2

Author(s):

Yong Jia ◽

Yong Guo ◽

Chao Yan ◽

Haoxuan Sheng ◽

Guolong Cui ◽

...

Keyword(s):

Cross Correlation ◽

Continuous Wave ◽

Coefficient Matrix ◽

Constant False Alarm Rate ◽

Localization Algorithm ◽

Cfar Detection ◽

Stepped Frequency ◽

The Cross ◽

The One ◽

Detection And Localization

This paper demonstrates the feasibility of detection and localization of multiple stationary human targets based on cross-correlation of the dual-station stepped-frequency continuous-wave (SFCW) radars. Firstly, a cross-correlation operation is performed on the preprocessed pulse signals of two SFCW radars at different locations to obtain the correlation coefficient matrix. Then, the constant false alarm rate (CFAR) detection is applied to extract the ranges between each target and the two radars, respectively, from the correlation matrix. Finally, the locations of human targets is calculated with the triangulation localization algorithm. This cross-correlation operation mainly brings about two advantages. On the one hand, the cross-correlation explores the correlation feature of target respiratory signals, which can effectively detect all targets with different signal intensities, avoiding the missed detection of weak targets. On the other hand, the pairing of two ranges between each target and two radars is implemented simultaneously with the cross-correlation. Experimental results verify the effectiveness of this algorithm.

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Short-term earthquake forecasting experiment before and during the L’Aquila (central Italy) seismic sequence of April 2009

Annals of Geophysics ◽

10.4401/ag-6583 ◽

2015 ◽

Vol 57 (6) ◽

Author(s):

Maura Murru ◽

Jiancang Zhuang ◽

Rodolfo Console ◽

Giuseppe Falcone

Keyword(s):

Central Italy ◽

Aftershock Sequence ◽

Earthquake Forecasting ◽

Model Parameters ◽

Short Term ◽

Productivity Function ◽

Epidemic Type Aftershock Sequence ◽

Forecasting Performance ◽

The One ◽

Lower Magnitude

<div class="page" title="Page 1"><div class="layoutArea"><div class="column"><p>In this paper, we compare the forecasting performance of several statistical models, which are used to describe the occurrence process of earthquakes in forecasting the short-term earthquake probabilities during the L’Aquila earthquake sequence in central Italy in 2009. These models include the Proximity to Past Earthquakes (PPE) model and two versions of the Epidemic Type Aftershock Sequence (ETAS) model. We used the information gains corresponding to the Poisson and binomial scores to evaluate the performance of these models. It is shown that both ETAS models work better than the PPE model. However, in comparing the two types of ETAS models, the one with the same fixed exponent coefficient (<span>alpha)</span> = 2.3 for both the productivity function and the scaling factor in the spatial response function (ETAS I), performs better in forecasting the active aftershock sequence than the model with different exponent coefficients (ETAS II), when the Poisson score is adopted. ETAS II performs better when a lower magnitude threshold of 2.0 and the binomial score are used. The reason is found to be that the catalog does not have an event of similar magnitude to the L’Aquila mainshock (M<sub>w</sub> 6.3) in the training period (April 16, 2005 to March 15, 2009), and the (<span>alpha)</span>-value is underestimated, thus the forecast seismicity is underestimated when the productivity function is extrapolated to high magnitudes. We also investigate the effect of the inclusion of small events in forecasting larger events. These results suggest that the training catalog used for estimating the model parameters should include earthquakes of magnitudes similar to the mainshock when forecasting seismicity during an aftershock sequence.</p></div></div></div>

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Evaluation of hadronic emission in starburst galaxies and star-forming galaxies

Research in Astronomy and Astrophysics ◽

10.1088/1674-4527/21/10/263 ◽

2021 ◽

Vol 21 (10) ◽

pp. 263

Author(s):

Yun-Chuan Xiang ◽

Ze-Jun Jiang ◽

Yun-Yong Tang

Keyword(s):

Supernova Remnants ◽

Milky Way ◽

Starburst Galaxies ◽

Model Parameters ◽

Zone Model ◽

Observation Data ◽

Large Area ◽

Star Forming ◽

Ngc 1068 ◽

The One

Abstract In this work, we reanalyzed 11 years of spectral data from the Fermi Large Area Telescope (Fermi-LAT) of currently observed starburst galaxies (SBGs) and star-forming galaxies (SFGs). We used a one-zone model provided by NAIMA and the hadronic origin to explain the GeV observation data of the SBGs and SFGs. We found that a protonic distribution of a power-law form with an exponential cutoff can explain the spectra of most SBGs and SFGs. However, it cannot explain the spectral hardening components of NGC 1068 and NGC 4945 in the GeV energy band. Therefore, we considered the two-zone model to well explain these phenomena. We summarized the features of two model parameters, including the spectral index, cutoff energy, and proton energy budget. Similar to the evolution of supernova remnants (SNRs) in the Milky Way, we estimated the protonic acceleration limitation inside the SBGs to be the order of 102 TeV using the one-zone model; this is close to those of SNRs in the Milky Way.

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Taking into Account both Explicit Conduits and the Unsaturated Zone in Karst Reservoir Hybrid Models: Impact on the Outlet Hydrograph

Water ◽

10.3390/w12113221 ◽

2020 ◽

Vol 12 (11) ◽

pp. 3221

Author(s):

Lucie Dal Soglio ◽

Charles Danquigny ◽

Naomi Mazzilli ◽

Christophe Emblanch ◽

Gérard Massonnat

Keyword(s):

Unsaturated Zone ◽

Numerical Models ◽

Karst Aquifer ◽

Hybrid Models ◽

Model Parameters ◽

Transit Times ◽

The Matrix ◽

Karst Reservoir ◽

Karst Systems ◽

The One

The main outlets of karst systems are springs, the hydrographs of which are largely affected by flow processes in the unsaturated zone. These processes differ between the epikarst and transmission zone on the one hand and the matrix and conduit on the other hand. However, numerical models rarely consider the unsaturated zone, let alone distinguishing its subsystems. Likewise, few models represent conduits through a second medium, and even fewer do this explicitly with discrete features. This paper focuses on the interest of hybrid models that take into account both unsaturated subsystems and discrete conduits to simulate the reservoir-scale response, especially the outlet hydrograph. In a synthetic karst aquifer model, we performed simulations for several parameter sets and showed the ability of hybrid models to simulate the overall response of complex karst aquifers. Varying parameters affect the pathway distribution and transit times, which results in a large variety of hydrograph shapes. We propose a classification of hydrographs and selected characteristics, which proves useful for analysing the results. The relationships between model parameters and hydrograph characteristics are not all linear; some of them have local extrema or threshold limits. The numerous simulations help to assess the sensitivity of hydrograph characteristics to the different parameters and, conversely, to identify the key parameters which can be manipulated to enhance the modelling of field cases.

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Enhanced Performances of SAC-OCDMA System by Using Polarization Encoding

Journal of Optical Communications ◽

10.1515/joc-2017-0182 ◽

2018 ◽

Vol 0 (0) ◽

Author(s):

Ahmed Garadi ◽

Boubakar S. Bouazza ◽

Abdelkader Bouarfa ◽

Khansae Meddah

Keyword(s):

Optical Communication ◽

Bit Error Rate ◽

Multiple Access ◽

Cross Correlation ◽

Spectral Amplitude ◽

Orthogonal Polarization ◽

Optical Communication System ◽

One Dimensional ◽

Polarization Encoding ◽

The One

Abstract This article presents a novel encoder technique of spectral amplitude coded multiple access (SAC-OCDMA) systems. The proposed technique is based on two orthogonal polarization states of the same one dimensional optical code. This method is usually applied to increase the number of simultaneous users in a network, and it can double the number of potential users against the one-dimensional code. The results obtained in this work show that optical zero cross-correlation code can accommodate more users simultaneously for the typical bit error rate of optical communication system of ${\ }{10^{ - 9}}$ .

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Vector Positioning for Cross Correlation PIV

Volume 2: Symposia and General Papers, Parts A and B ◽

10.1115/fedsm2002-31171 ◽

2002 ◽

Author(s):

C. N. Young ◽

R. Gilbert ◽

D. A. Johnson ◽

E. J. Weckman

Keyword(s):

Cross Correlation ◽

Full Range ◽

Reduction Process ◽

Particle Number Density ◽

Particle Dispersion ◽

Correlation Peak ◽

Measured Velocity ◽

Velocity Gradients ◽

Positional Bias ◽

The Cross

Continuing advances in digital imaging technology stimulate greater interest in applying particle image velocimetry (PIV) over increasingly larger fields of view. Unfortunately when larger fields of view are analyzed, velocity gradients in the image become more localized. In addition, non-uniformities in image illumination and particle number density become more prevalent. These factors, coupled with the requirement that large areas of interest (AOIs) must be employed to measure the full range of velocity, cause degradation of correlation results (i.e. broadening and/or splintering of the cross correlation peak) which leads to positional bias errors in the measured velocity field. More advanced super resolution strategies that employ an iterative AOI reduction process inherently reduce positional bias in PIV results but these strategies can break down in complex flows where velocity gradients are steep and particle dispersion does not remain uniformly random. To mitigate these problems a simple but effective technique is presented that enables individual velocity vectors to be placed within an AOI at locations toward which the cross correlation plane is biased. The method involves analysis of the correlation plane to extract the dominant features that are matched in two successive AOIs. To demonstrate the utility of the methodology results obtained from synthetic images are compared against results obtained using the conventional PIV approach.

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Stable Stationary Solitons of the One-Dimensional Modified Complex Ginzburg-Landau Equation

Zeitschrift für Naturforschung A ◽

10.1515/zna-2007-7-803 ◽

2007 ◽

Vol 62 (7-8) ◽

pp. 368-372

Author(s):

Woo-Pyo Hong

Keyword(s):

Landau Equation ◽

Model Parameters ◽

Ginzburg Landau ◽

One Dimensional ◽

Paraxial Ray Approximation ◽

New Family ◽

Ginzburg Landau Equation ◽

The Stability ◽

The One ◽

Paraxial Ray

We report on the existence of a new family of stable stationary solitons of the one-dimensional modified complex Ginzburg-Landau equation. By applying the paraxial ray approximation, we obtain the relation between the width and the peak amplitude of the stationary soliton in terms of the model parameters. We verify the analytical results by direct numerical simulations and show the stability of the stationary solitons.

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Simple framework for constructing functional spiking recurrent neural networks

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1905926116 ◽

2019 ◽

Vol 116 (45) ◽

pp. 22811-22820 ◽

Cited By ~ 6

Author(s):

Robert Kim ◽

Yinghao Li ◽

Terrence J. Sejnowski

Keyword(s):

Neural Networks ◽

Recurrent Neural Networks ◽

Continuous Variable ◽

Model Parameters ◽

Additional Parameter ◽

Wide Range ◽

Close Relationship ◽

Rate Coding ◽

One To One ◽

The One

Cortical microcircuits exhibit complex recurrent architectures that possess dynamically rich properties. The neurons that make up these microcircuits communicate mainly via discrete spikes, and it is not clear how spikes give rise to dynamics that can be used to perform computationally challenging tasks. In contrast, continuous models of rate-coding neurons can be trained to perform complex tasks. Here, we present a simple framework to construct biologically realistic spiking recurrent neural networks (RNNs) capable of learning a wide range of tasks. Our framework involves training a continuous-variable rate RNN with important biophysical constraints and transferring the learned dynamics and constraints to a spiking RNN in a one-to-one manner. The proposed framework introduces only 1 additional parameter to establish the equivalence between rate and spiking RNN models. We also study other model parameters related to the rate and spiking networks to optimize the one-to-one mapping. By establishing a close relationship between rate and spiking models, we demonstrate that spiking RNNs could be constructed to achieve similar performance as their counterpart continuous rate networks.

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