Miracle-dz/UniFAR-FTUs huggingface dataset:
Dissipation and decoherence in quantum systems

The theory of dissipative quantum systems and its relation to the quantum theory of continuous measurements are reviewed. Constructing a correct theory of a dissipative quantum system requires that the system's interaction with its environment (reservoir) be taken into account. Since information about the system is 'recorded' in the state of the reservoir, the quantum theory of continuous measurements can be used to account for the influence of the reservoir. If based on the use of restricted path integrals, this theory does not require an explicit reservoir model and is therefore much simpler technically.
Probing the Dark Matter mass and nature with neutrinos

We study the possible indirect neutrino signal from dark matter annihilations inside the Sun's core for relatively light dark matter masses in the 𝒪(10) GeV range. Due to their excellent energy reconstruction capabilities, we focus on the detection of this flux in liquid argon or magnetized iron calorimeter detectors, proposed for the next generation of far detectors of neutrino oscillation experiments and neutrino telescopes. The aim of the study is to probe the ability of these detectors to determine fundamental properties of the dark matter nature such as its mass or its relative annihilation branching fractions to different channels. We find that these detectors will be able to accurately measure the dark matter mass as long as the dark matter annihilations have a significant branching into the neutrino or at least the τ channel. We have also discovered degeneracies between different dark matter masses and annihilation channels, where a hard τ channel spectrum for a lower dark matter mass may mimic that of a softer quark channel spectrum for a larger dark matter mass. Finally, we discuss the sensitivity of the detectors to the different branching ratios and find that it is between one and two orders of magnitude better than the current bounds from those coming from analysis of Super-Kamiokande data.
Galactic signatures of decaying dark matter

If dark matter decays into electrons and positrons, it can affect Galactic radio emissions and the local cosmic ray fluxes. We propose a new, more general analysis of constraints on dark matter. The constraints can be obtained for any decaying dark matter model by convolving the specific dark matter decay spectrum with a response function. We derive this response function from full-sky radio surveys at 408 MHz, 1.42 GHz and 23 GHz, as well as from the positron flux recently reported by PAMELA. We discuss the influence of astrophysical uncertainties on the response function, such as from propagation and from the profiles of the dark matter and the Galactic magnetic field. As an application, we find that some widely used dark matter decay scenarios can be ruled out under modest assumptions.
Laser acceleration of thin foils

A method for studying the characteristics of laser-induced ablative acceleration of thin foils is described. The method is based on the electrocontact measurement of the time of foil flight through base distances in the air atmosphere. Results of experiments on the laser acceleration of foils in cylindrical and conical channels for laser radiation intensities up to 2×1011 W cm-2 are presented. The results obtained were used in experiments to determine the split-off strength of aluminium targets at high strain rates, the accelerated aluminium foils being used as strikers.
Equilateral non-gaussianity and new physics on the horizon

We examine the effective theory of single-field inflation in the limit where the scalar perturbations propagate with a small speed of sound. In this case the non-linearly realized time-translation symmetry of the Lagrangian implies large interactions, giving rise to primordial non-Gaussianities. When the non-Gaussianities are measurable, these interactions will become strongly coupled unless new physics appears close to the Hubble scale. Due to its proximity to the Hubble scale, the new physics is not necessarily decoupled from inflationary observables and can potentially affect the predictions of the model. To understand the types of corrections that may arise, we construct weakly-coupled completions of the theory and study their observational signatures.
Simultaneous MEG and EEG source analysis

A method is described to derive source and conductivity estimates in a simultaneous MEG and EEG source analysis. In addition the covariance matrix of the estimates is derived. Simulation studies with a concentric spheres model and a more realistic boundary element model indicate that this method has several advantages, even if only a few EEG sensors are added to a MEG configuration. First, a simultaneous analysis profits from the `preferred' location directions of MEG and EEG. Second, deep sources can be estimated quite accurately, which is an advantage compared to MEG. Third, superficial sources profit from accurate MEG location and from accurate EEG moment. Fourth, the radial source component can be estimated, which is an advantage compared to MEG. Fifth, the conductivities can be estimated. It is shown that conductivity estimation gives a substantial increase in precision, even if the conductivities are not identified appropriately. An illustrative analysis of empirical data supports these findings.
Study of the performance of a large scale water-Cherenkov detector (MEMPHYS)

MEMPHYS (MEgaton Mass PHYSics) is a proposed large-scale water Cherenkov experiment to be performed deep underground. It is dedicated to nucleon decay searches, neutrinos from supernovae, solar and atmospheric neutrinos, as well as neutrinos from a future Super-Beam or Beta-Beam to measure the CP violating phase in the leptonic sector and the mass hierarchy. A full simulation of the detector has been performed to evaluate its performance for beam physics. The results are given in terms of ``migration matrices'' of reconstructed versus true neutrino energy, taking into account all the experimental effects.
γ-ray diagnostics of energetic ions in JET

This paper reports recent progress in the field of γ-ray diagnosis of fast ions in the JET tokamak. The γ-rays, born in nuclear reactions between fast ions and main plasma impurities and/or plasma fuel ions, are analysed with a new modelling tool (the GAMMOD code) that has been developed for a quantitative analysis of the measured γ-ray energy spectra. The analysis of the γ-ray energy spectra identifies the different fast ions giving rise to the γ-ray emission and assesses the effective tail temperatures and relative concentrations of these fast ions. This assessment is possible, since the excitation functions for the different nuclear reactions are well established and exhibit a threshold or/and a resonant nature. The capabilities of the γ-ray spectral analysis are illustrated with the examples from the recent γ-ray diagnostic measurements of 4He, 3He, deuterium and hydrogen ions accelerated by ion-cyclotron resonance frequency heating in JET. Simultaneous measurements of several fast ion species, including highly energetic α-particles, are demonstrated. In addition to the γ-spectroscopy, tomographic reconstructions of the radial profile of the γ-ray emission are performed using the JET neutron profile monitor, thus providing direct measurements of the radial profiles of fast ions in JET.
Simultaneous effect of modified gravity and primordial non-Gaussianity in large scale structure observations

In this work we study the simultaneous effect of primordial non-Gaussianity and the modification of the gravity in f(R) framework on large scale structure observations. We show that non-Gaussianity and modified gravity introduce a scale dependent bias and growth rate functions. The deviation from ΛCDM in the case of primordial non-Gaussian models is in large scales, while the growth rate deviates from ΛCDM in small scales for modified gravity theories. We show that the redshift space distortion can be used to distinguish positive and negative fNL in standard background, while in f(R) theories they are not easily distinguishable. The galaxy power spectrum is generally enhanced in presence of non-Gaussianity and modified gravity. We also obtain the scale dependence of this enhancement. Finally we define galaxy growth rate and galaxy growth rate bias as new observational parameters to constrain cosmology.
The Generalized Emden-Fowler Equation

We give the description of nonlinear nonautonomous ordinary differential equations of order n with a so-called reducible linear part. The group classification of generalized Emden-Fowler equations of the mentioned class is done. We have found such laws of the variation of f (x) that the equation admits one, two, or tree one-parameter Lie groups.
A Fast Three-Dimensional Display Method for Time-Frequency Spectrogram Used in Embedded Fault Diagnosis Devices

Time-frequency analysis is usually used to reveal the appearance of different frequency components varying with time, in signals, of which time-frequency spectrogram is an important visual tool to display the information. The Mesh Surface Generation (MSG) algorithm is widely used in three-dimensional (3D) modeling. Removing hidden lines from the mesh plot is an essential process that produces explicit depth information. In this paper, a fast and effective method has been proposed for a time-frequency Spectrogram Mesh Surface Generation (SMSG) display, especially, based on the painter’s algorithm. In addition, most portable fault diagnosis devices have little function to generate a 3D spectrogram, which generally needs a general computer to realize the complex time-frequency analysis algorithms and a 3D display. However, general computer is not portable and then not suitable for field test. Hence, the proposed SMSG algorithm is applied to an embedded fault diagnosis device, which is light, low-cost, and real-time. The experimental results show that this approach can realize a high degree of accuracy and save considerable time.
Application of the MLPG Mixed Collocation Method forSolving Inverse Problems of Linear Isotropic/AnisotropicElasticity with Simply/Multiply-Connected Domains

In this paper, a novel Meshless Local Petrov-Galerkin (MLPG) Mixed Collocation Method is developed for solving the inverse Cauchy problem of linear elasticity, wherein both the tractions as well as displacements are prescribed/ measured at a small portion of the boundary of an elastic body. The elastic body may be isotropic/anisotropic and simply connected or multiply-connected. In the MLPG mixed collocation method, the same meshless basis function is used to interpolate both the displacement as well as the stress fields. The nodal stresses are expressed in terms of nodal displacements by enforcing the constitutive relation between stress and the displacement gradient tensor at each nodal point. The equations of linear momentum balance are satisfied at each node using collocation method. The displacement as well as traction boundary conditions are also enforced at each measurement location along the boundary where the conditions are over specified on displacement as well as tractions. The current method is very simple because the inverse problem is directly solved in a fashion similar to a direct problem, without resorting to any iterative optimization. The current method is also very general because it can be applied to arbitrary simply/multiply connected bodies composed of arbitrary isotropic/anisotropic material, and it can also be adapted to solve inverse problems of other physics such as heat transfer, electro-magnetics, etc. Several numerical examples demonstrate the effectiveness and robustness of the current method, even when the prescribed displacement/tractions are corrupted with measurement noises. The extension of the current method to solve nonlinear inverse problems will be straightforward within the framework of incremental 1 School of Aeronautic Science and Engineering, Beihang University, Beijing, China. 2 Center for Aerospace Research & Education, University of California, Irvine, USA. 3 Corresponding Author. Department of Engineering Mechanics, Hohai University, Nanjing, China. Email: dong.leiting@gmail.com 4 Department of Mathematics, King Abdulaziz University, Jeddah, Saudi Arabia. 5 Distinguished Adjunct-Professor of Multi-Disciplinary Engineering and Computer Science, King Abdulaziz University, Jeddah, Saudi Arabia. 2 Copyright © 2013 Tech Science Press CMES, vol.94, no.1, pp.1-28, 2013 loading, which will be explored in future studies.
Optimal Information Provision at Bottleneck Equilibrium with Risk-Averse Travelers

This paper aims to study the effects of travel information provision on risk-averse travelers when travel time is uncertain. A stochastic bottleneck model is examined with risk-averse commuters, in which the free-flow travel time is assumed to be uncertain and follows a uniform distribution. A mean-variance approach is adopted to measure the travel cost under risk. It is proven that the individual travel cost at bottleneck equilibrium monotonically increases with the risk-aversion level. With a higher risk-aversion level, the morning peak hour starts earlier, but the duration of the peak hour remains constant regardless of the risk-aversion level. If improvement in information quality can reduce the travel time uncertainty, risk-averse commuters will benefit from the higher quality of information. Nevertheless, when the cost of information provision is also considered, the optimal information provision strategy is derived to minimize the total system cost. The numerical examples demonstrate the information efficiency and provision strategy. The findings reveal the congestion patterns of a stochastic bottleneck with risk-averse travelers and will guide us to provide appropriate travel information.
A study of coupling loss on bi-columnar BSCCO/Ag tapes through ac susceptibility measurements

Coupling losses were studied in composite tapes containing superconducting material in the form of two separate stacks of densely packed filaments embedded in a metallic matrix of Ag or Ag alloy. This kind of sample geometry is quite favourable for studying the coupling currents and, in particular, the role of superconducting bridges between filaments. By using the ac susceptibility technique, the electromagnetic losses as a function of ac magnetic field amplitude and frequency were measured at the temperature T = 77 K for two tapes with different matrix composition. The length of the tapes was varied by subsequent cutting in order to investigate its influence on the dynamics of magnetic flux penetration. The geometrical factor χ0 which takes into account the demagnetizing effects was established from ac susceptibility data at low amplitudes. Losses versus frequency dependencies have been found to agree nicely with the theoretical model developed for round multifilamentary wires. Applying this model, the effective resistivity of the matrix was determined for each tape by using only measured quantities. For the tape with a pure silver matrix its value was found to be larger than that predicted by the theory for given metal resistivity and filamentary architecture. In contrast, in the tape with a Ag/Mg alloy matrix, an effective resistivity much lower than expected was determined. We explain these discrepancies by taking into account the quality of the interface between the superconducting filaments and the normal matrix. In the case of a soft matrix of pure Ag, this is of poor quality, while the properties of the alloy matrix seem to provoke the extensive creation of intergrowths which can be actually observed in these kind of tapes.
Measuring coherent motions in the universe

We present new measurements of the coherent motion of galaxies based on observations of the large-scale redshift-space distortions seen in the two-dimensional two-point correlation function of Luminous Red Galaxies in Data Release Seven of the Sloan Digital Sky Survey. We have developed a new methodology for estimating these coherent motions, which is less dependent on the details of galaxy bias and of the cosmological model to explain the late-time acceleration of the expansion of the Universe. We measure a one-dimensional velocity dispersion of galaxies on large-scales of σv = h-1 Mpc and σv = h-1 Mpc at a mean redshift of z = 0.25 and 0.38 respectively. These values are fully consistent with predictions for a WMAP7-normalised ΛCDM Universe and inconsistent at confidence of 3. 8σ with a Dvali-Gabadadze-Porrati (DGP) model for the Universe. We can convert the units of these σv measurements to km/s and km/s respectively (assuming a ΛCDM universe), which are lower that expected based on recent low redshift (z < 0.2) measurements of the peculiar velocity field (or “bulk flows”). It is difficult to directly compare these measurements as they cover different redshift ranges and different areas of the sky. However, one possible cosmological explanation for this discrepancy is that our Galaxy is located in unusually over, or under, dense region of the Universe.
3D Printed Helix Antenna

The goal of this paper is to show the possibility of fabricating helix antennas with incorporated reflector up to mm-wave frequencies by additive manufacturing. As an example, a monofilar helix for a center frequency of 11 GHz was manufactured additively on a PEEK substrate by using an aerosol jet printing system. Measurements affirm a gain of approximately 5.6 dBi with an axial ratio below 3 dB over more than 1 GHz of bandwidth. Furthermore, the effects of mechanical tolerances on the fabricated antenna's performance are analyzed and the future potential of the proposed fabrication approach is highlighted.
A Comprehensive Harmonic Analysis and Control Strategy for Improved Input Power Quality in a Cascaded Modular Solid State Transformer

In a three-stage cascaded modular solid state transformer (CMSST), unbalanced dc bus voltages at the output of cascaded multilevel rectifier is a common issue due to inevitable parameter mismatch in stage-2. To balance the dc bus voltages, either voltage balance control (VBC) in stage-1 or power balance control (PBC) in stage-2 is necessary. In this paper, an in-depth theoretical analysis to investigate the input power quality of the CMSST in the presence of voltage and PBC schemes is presented. The grid-side multilevel voltage of the CMSST is analyzed to highlight the limitation of using VBC in stage-1. It is then mathematically proven that the switching frequency based harmonics in the grid current are significantly reduced by using the PBC in stage-2. Simulation studies of a 3.3-kV, 50-kVA CMSST are carried out using the PLECS software to substantiate the proposed analysis. Experimental verifications are performed on a 750-VA single-phase CMSST laboratory prototype for a 20% parameter mismatch in stage-2. It is found that the grid current total harmonic distortion (THD) is reduced from 6.65% to 3.8% at 50% load by using PBC in stage-2. This paper provides guidelines for the designer to choose appropriate balance controllers for the CMSST.
Spin-polarized scanning tunnelling microscopy

The recent experimental progress in spin-polarized scanning tunnelling microscopy (SP-STM)—a magnetically sensitive imaging technique with ultra-high resolution—is reviewed. The basics of spin-polarized electron tunnelling are introduced as they have been investigated in planar tunnel junctions for different electrode materials, i.e. superconductors, optically excited GaAs, and ferromagnets. It is shown that ferromagnets and antiferromagnets are suitable tip materials for the realization of SP-STM. Possible tip designs and modes of operations are discussed for both classes of materials. The results of recent spatially resolved measurements as performed with different magnetic probe tips and using different modes of operation are reviewed and discussed in terms of applicability to surfaces, thin films, and nanoparticles. The limits of spatial resolution, and the impact of an external magnetic field on the imaging process are debated.
Structural Assessment of Ancient Masonries before and during a Rehabilitation Process

ABSTRACT The rehabilitation of old buildings requires detailed knowledge of the mechanical characteristics and stress state of the structural elements, which play an important role in the intervention process. In this sense, non-slightly destructive tests can estimate structural characteristics with good precision at relatively low costs. Consequently, this article presents a device, based on the flat jack technique, applied to continuous stress monitoring over time. It also focuses on the onsite determination of service stresses and its continuous monitoring in several masonry buttresses of a historic building, as well as the assessment of the structural safety before, during, and after an intervention process. A brief analysis of the research is performed, and the motivation and the methodology adopted are described. Finally, the evolution of the measurements recorded and the analysis of the results achieved are detailed. The study enabled recommendations to be made to the intervening agents that guarantee structural safety.
CERASPECT: a brain-dedicated SPECT system. Performance evaluation and comparison with the rotating gamma camera

Physical parameters and performance of a new brain-dedicated tomograph (CERASPECT) were measured and compared to those of a state-of-the-art single-headed rectangular rotating gamma camera. Spatial resolution, sensitivity, scatter fraction, contrast, uniformity and image quality of the two systems were evaluated using the same radioactive source geometry. The CERASPECT's spatial resolution was 23% higher and its sensitivity was three times greater than those of the gamma camera. The contrast measured with a 15 mm cold lesion was 60% for the CERASPECT and 45% for the gamma camera. Tomographic nonuniformities were measured as the percentage integral and differential uniformity of a cylindrical uniform phantom. At low-statistics counts per slice the integral uniformity was comparable and at high-statistics counts per slice it was equal to 11% and 20% for CERASPECT and the gamma camera, respectively. Image quality is generally superior with the dedicated brain system. The use of new devices with improved physical performance allows more accurate quantitative SPECT functional brain studies.