Miracle-dz/UniFAR-FTUs huggingface dataset:
Reciprocity theorems for one-way wavefields

SUMMARY Acoustic reciprocity theorems have proved their usefulness in the study of forward and inverse scattering problems. The reciprocity theorems in the literature apply to the two-way (i.e. total) wavefield, and are thus not compatible with one-way wave theory, which is often applied in seismic exploration. By transforming the two-way wave equation into a coupled system of one-way wave equations for downgoing and upgoing waves it appears to be possible to derive ‘one-way reciprocity theorems’ along the same lines as the usual derivation of the ‘two-way reciprocity theorems’. However, for the one-way reciprocity theorems it is not directly obvious that the ‘contrast term’ vanishes when the medium parameters in the two different states are identical. By introducing a modal expansion of the Helmholtz operator, its square root can be derived, which appears to have a symmetric kernel. This symmetry property appears to be sufficient to let the contrast term vanish in the above-mentioned situation. The one-way reciprocity theorem of the convolution type is exact, whereas the oneway reciprocity theorem of the correlation type ignores evanescent wave modes. The extension to the elastodynamic situation is not trivial, but it can be shown relatively easily that similar reciprocity theorems apply if the (non-unique) decomposition of the elastodynamic two-way operator is done in such a way that the elastodynamic one-way operators satisfy similar symmetry properties to the acoustic one-way operators.
Analysis of 980nm emitting single-spatial mode diode lasers at high power levels by complementary imaging techniques

Pulsed operation of standard 980-nm emitting single-spatial-mode high power diode lasers at multi-watt power levels is studied. Primary emission, short wavelength infrared emission, as well as the spatio-temporal evolution of the near field are recorded. This approach allows for the determination of the operation parameters during which single-mode operation is maintained. This gives limits of safe operation far beyond the standard specifications as well as information about the relevant degradation mechanisms in this regime. Reference experiments with a set of long-term operated devices reveal gradual aging signatures and the starting points of the relevant aging processes become detectable. They are compared with those obtained from the devices operated under pulsed conditions.
A nonlinear control scheme for fast settling in hard disk drives

Conventional integral compensation to deal with unknown bias usually leads to long settling process in hard disk drives. This paper proposes a nonlinear proportional integral derivative control scheme to shorten the settling time by reducing the overshoot caused by the integrator, without degradation of other performance specifications. Experiment results show that it is robust against different bias sizes and step sizes. Furthermore, the single-track seek time can scale down well with the track pitch.
New approaches to electroweak symmetry breaking

Although the spectacular experimental achievements of particle physics in the last decade have strengthened the Standard Model (SM) as an adequate description of nature, they have also revealed that the SM matter represents a mere 5% or so of the energy density of the Universe, which clearly points to some physics beyond the SM despite the desperate lack of direct experimental evidence. The sector responsible for the spontaneous breaking of the SM electroweak symmetry is likely to be the first to provide experimental hints at this new physics. The aim of this review is, after briefly introducing SM physics and the conventional Higgs mechanism, to give a survey of recent ideas on how the dynamics of electroweak symmetry breaking can be explained.
The Role of Political Sophistication in the Decision-Making Processes of Voters

Since the origination of the scientific study of voting behavior in the 1950s and 1960s, political scientists have developed several models of voting behavior. As those models were tested empirically, scholars were faced with a seeming contradiction: while voters in general are poorly-informed about politics, they nonetheless are capable of making voting decisions that are consistent with their fully informed preferences.Lodge, Stroh and Wahlke (1990) posited that none of these preexisting models could adequately explain voter behavior, because they failed to explain the mechanisms that led to voters' decisions. However, relatively few studies have been done to understand how these mechanisms work, and the areas of research that have attempted to explain these mechanisms have generally been seen as lacking methodological rigor. In more recent years, scholars have looked at the use of heuristics and affect as "cognitive shortcuts," but have generally failed to provide a compelling explanation of how and when voters can make use of them, beyonddemonstrating that they appear to do so. In particular, relatively little attention has been paid to the question of which heuristics are available to particular voters. While the use of heuristics is generally considered to be an individual-level phenomenon, we should expect that various groups of voters should process information in similar ways. In particular, it is reasonable to believe that voters who are more aware of politics can draw upon more sources of information when making evaluations, while less sophisticated voters are more limited in their ability to draw inferences due to their lack of knowledge.This dissertation demonstrates how voters make use of political information and heuristic devices in different ways based primarily on their their level of political sophistication--their ability to comprehend and apply political information when evaluating issues or making voting decisions.
Efficient implementation of `Optimal' algorithms in computerized tomography

We describe three optimal algorithms for the reconstruction of a function in mathbb{R}^{2} from a finite number of line or strip integrals: Optimal recovery, Bayes estimate, Tikhonov-Phillips method. In the case of a rotationally invariant scanning geometry we show that the resulting linear system is a bloc-cyclic convolution. This observation leads to algorithms which are roughly as efficient as filtered backprojection which is one of the standard methods. The algorithms can be applied to the case of hollow and truncated projections. Numerical examples are given.
An X-ray Temperature Map of Abell 1795, a Galaxy Cluster in Hydrostatic Equilibrium

We present the first two-dimensional X-ray temperature map of the galaxy cluster Abell 1795, which harbors a strong cooling flow. We also present an X-ray surface brightness map of the cluster. The temperature map clearly shows a cool region coincident with the peak X-ray surface brightness and with the cD galaxy. Outside this region, there is no significant temperature structure. The X-ray isophotes are slightly elliptical but very smooth, with a small asymmetry to the north, coincident with a region of enhanced galaxy density. All these observations are consistent with an evolutionary scenario in which clusters without recent mergers have had enough time for the bulk of the cluster to equilibrate, becoming isothermal except for the centers which develop cooling flows. Since A1795 is likely to be nearly spherically symmetric and in hydrostatic equilibrium, it should be possible to estimate the total mass and gas mass fraction relatively free of systematic errors. Within a radius of 0.5 h−1 Mpc, the radius to which we have temperature measurements, the total mass is 2.7 ± 0.22 × 1014 h−1 M☉ , of which the gas contributes 4.6 ± 0.9 h−1.5 percent. We do not confirm the high value of excess absorbing material in the cooling flow region found previously using other instruments.
Millimeter/submillimetre-wave Cosmology: mm-wave Test Cryostat Design, Deployment and SCUBA-2/SMA Observations of the H1549 Overdense Galaxy Protocluster

xi List of Abbreviations and Symbols Used . xii Acknowledgements . xiv Chapter
On unified boundary conditions for improved predictions of near-wall turbulence

A novel formulation of the wall boundary conditions relying on the asymptotic behaviour of the Taylor microscale λ and its relationship to the homogeneous part of the viscous dissipation rate of the kinetic energy of turbulence εh =5νq2/λ2, applicable to near-wall turbulence, is examined. The linear dependence of λ on the wall distance in close proximity to the solid surface enables the wall-closest grid node to be positioned immediately below the edge of the viscous sublayer, leading to a substantial coarsening of the grid resolution. This approach provides bridging of a major portion of the viscous sublayer, higher grid flexibility and weaker sensitivity against the grid non-uniformities in the near-wall region. The performance of the proposed formulation was checked against available direct numerical simulation databases of complex wall-bounded flows featured by swirl and separation.
Algorithms for ambiguity function processing

Calculation of the complex ambiguity function is viewed as the basis for joint estimation of the differential delay and differential frequency offset between two waveforms that contain a common component plus additive noise. In many applications, the required accuracy leads to a need for integration over long data sets that can become a challenge for near real-time digital processing. The nature of the ambiguity processing is interpreted, and an algorithm approach is shown that minimizes the processing burden over a broad category of applications without affecting performance.
SiGe nanowires: Structural stability, quantum confinement, and electronic properties

We report first-principles calculations of [110] SiGe NWs; we discuss the effect of geometry and composition on their thermodynamic stability, on their electronic properties, and on the nature of the quantum confinement effect. The analysis of formation enthalpy reveals that ${\text{Ge}}_{core}/{\text{Si}}_{shell}$ NWs represent the most stable structure at any diameter, as a confirmation of the results of many experimental works. The study of the dependence of the energy band gap on the composition and geometry shows how abrupt NWs (wires with a clear flat interface between Si and Ge) present strongly reduced quantum confinement effect and offer a very easy way to predict and to engine energy band gap, which can have a strong relevance from a technological point of view. A careful analysis of the influence of composition on the wave-function localization and quantum confinement effect is also presented, in particular, for core-shell NWs.
Membranes with Fluctuating Topology: Monte Carlo Simulations

Much of the phase behavior observed in self-assembling amphiphilic systems can be understood in the context of ensembles of random surfaces. In this article, it is shown that Monte Carlo simulations of dynamically triangulated surfaces of fluctuating topology can be used to determine the structure and thermal behavior of sponge phases, as well as the sponge-to-lamellar transition in these systems. The effect of the saddle-splay modulus, $\overline{\ensuremath{\kappa}}$, on the phase behavior is studied systematically for the first time. Our data provide strong evidence for a positive logarithmic renormalization of $\overline{\ensuremath{\kappa}}$; this result is consistent with the lamellar-to-sponge transition observed in experiments for decreasing amphiphile concentration.
THERMAL EMISSION RATES OF CARRIERS AT GOLD CENTERS IN SILICON

Thermal emission rates of electrons and holes at the gold‐acceptor center (EC − EAu− = 550 mV) and of holes at the gold‐donor center (EAu+ − EV = 350 mV) are measured using the dark current, dark capacitance, and photocapacitance transient methods. About ten decades of the electron emission rate and eight decades of the hole emission rates are obtained in the temperature range of −160 to +100°C. The data correspond to electric fields of 104 and 105 V/cm maximum field in the p‐n junction and differ from the thermal equilibrium emission rates computed from previously published capture rate data at thermal equilibrium due to the field dependence of the capture rate from hot electron effect and of the emission rate from barrier lowering of the impurity potential.
XMM–Newton first X-ray detection of the low-ionization broad absorption line quasar PG 1700+518

We report the first high-energy detection of PG 1700+518, a well-known low-ionization broad absorption line quasar (quasi-stellar object, QSO). Due to previous X-ray non-detection, it was classified as soft X-ray weak QSO. We observed PG 1700+518 with XMM–Newton for about 60 ks divided in three exposures. The spectrum below 2 keV is very steep, � ∼ 2.4–3.8, while at higher energies the extremely flat emission (photon index � ∼ 0.15, when modelled with a power law) suggests the presence of strong absorption (NH,pl ∼ 2 × 10 23 cm −2 , � fixed to 1.8) or a reflection-dominated continuum. The broad-band flux is consistent with previous nondetection. Simultaneous European Photon Imaging Camera (EPIC) and Optical Monitor (OM) data confirm its X-ray weakness (observed αox ∼− 2.2). The level of obscuration derived from the X-ray spectra of PG 1700+518 cannot explain its soft X-ray nuclear weakness unless a column density of NH 2 × 10 24 cm −2 is present.
Asymptotic Analysis of lattice Boltzmann method for Fluid-Structure interaction problems

The lattice Boltzmann method (LBM) is a numerical solver for the Navier-Stokes equations, based on an underlying molecular dynamic model. Recently, it has been extended towardsthe simulation of complex fluids. We use the asymptotic expansion technique to investigate the standard scheme, the initialization problem and possible developments towards moving boundary and fluid-structure interaction problems. At the same time, it will be shown how the mathematical analysis can be used to understand and improve the algorithm. First of all, we elaborate the tool "asymptotic analysis", proposing a general formulation of the technique and explaining the methods and the strategy we use for the investigation. A first standard application to the LBM is described, which leads to the approximation of the Navier-Stokes solution starting from the lattice Boltzmann equation. As next, we extend the analysis to investigate origin and dynamics of initial layers. A class of initialization algorithms to generate accurate initial values within the LB framework is described in detail. Starting from existing routines, we will be able to improve the schemes in term of efficiency and accuracy. Then we study the features of a simple moving boundary LBM. In particular, we concentrate on the initialization of new fluid nodes created by the variations of the computational fluid domain. An overview of existing possible choices is presented. Performing a careful analysis of the problem we propose a modified algorithm, which produces satisfactory results. Finally, to set up an LBM for fluid structure interaction, efficient routines to evaluate forces are required. We describe the Momentum Exchange algorithm (MEA). Precise accuracy estimates are derived, and the analysis leads to the construction of an improved method to evaluate the interface stresses. In conclusion, we test the defined code and validate the results of the analysis on several simple benchmarks. From the theoretical point of view, in the thesis we have developed a general formulation of the asymptotic expansion, which is expected to offer a more flexible tool in the investigation of numerical methods. The main practical contribution offered by this work is the detailed analysis of the numerical method. It allows to understand and improve the algorithms, and construct new routines, which can be considered as starting points for future researches.
THREE PARADOXES FOR THE 'SMOOTH AMBIGUITY'MODEL OF PREFERENCE

Three Ellsberg-style thought experiments are described that re‡ect on the smooth ambiguity decision model developed by Klibano¤, Marinacci and Mukerji (2005). The …rst experiment poses di¢ culties for the model’s axiomatic foundations and, as a result, also for its interpretation, particularly for the authors’claim that the model achieves a separation between ambiguity and the attitude towards ambiguity. Given the problematic nature of its foundations, the behavioral content of the
Parameters affecting bending losses in graded-index polymer optical fibers

Radiation losses that occur when bending graded-index polymer optical fibers (POFs) are analyzed as a function of the profile exponent, the light wavelength, the fiber core radius, and the length of the bent section. For this purpose, a ray-tracing model is used, which combines both the generalized Fresnel power transmission coefficients for curved graded-index media and the differential equations that govern the ray paths in highly multimode graded-index fibers. This model is applied to the most recent types of graded-index POF, for which the choice of the core radius and profile exponent is discussed from the point of view of bending losses (the greater the profile exponent and the core radius, the greater the bending losses). The influence of profile exponents different from two is included for the first time.
THREE-DIMENSIONAL HYBRID SIMULATION STUDY OF ANISOTROPIC TURBULENCE IN THE PROTON KINETIC REGIME

Three-dimensional numerical hybrid simulations with particle protons and quasi-neutralizing fluid electrons are conducted for a freely decaying turbulence that is anisotropic with respect to the background magnetic field. The turbulence evolution is determined by both the combined root-mean-square (rms) amplitude for fluctuating proton bulk velocity and magnetic field and by the ratio of perpendicular to parallel wavenumbers. This kind of relationship had been considered in the past with regard to interplanetary turbulence. The fluctuations nonlinearly evolve to a turbulent phase whose net wave vector anisotropy is usually more perpendicular than the initial one, irrespective of the initial ratio of perpendicular to parallel wavenumbers. Self-similar anisotropy evolution is found as a function of the rms amplitude and parallel wavenumber. Proton heating rates in the turbulent phase vary strongly with the rms amplitude but only weakly with the initial wave vector anisotropy. Even in the limit where wave vectors are confined to the plane perpendicular to the background magnetic field, the heating rate remains close to the corresponding case with finite parallel wave vector components. Simulation results obtained as a function of proton plasma to background magnetic pressure ratio βp in the range 0.1–0.5 show that the wave vector anisotropy also weakly depends on βp.
Valveless pumping using traversing vapor bubbles in microchannels

Pumping of fluids in microchannels using the movement of a single or multiple vapor bubble(s) is proposed, analyzed, and demonstrated. The pumping mechanism requires no micromechanical moving parts for actuation by utilizing asymmetric heating which creates a variation in vapor pressure and surface tension due to the heater-induced temperature gradient along the channel. A heat and mass transfer analysis was performed to understand the pumping mechanism and estimate the pumping capability of the micropumping device. To verify the concept and our analysis, a pumping device with a transparent microchannel with a hydraulic diameter of 3.4 μm was fabricated on a silicon wafer using surface micromachining. Experimental results with the first generation device have shown pumping of isopropanol at velocities as high as 160 μm/s (0.5 nl/min flow rate) with a pressure head of approximately 800 Pa.
THE PERIOD OF AG PEGASI: HAVING ANOTHER GO.

The period of the symbiotic binary star AG Peg has been determined from photoelectric data, including previously unpublished data from the 1970s, as well as new observations. Altogether, 89 V magnitudes are available for discussion. These are corrected for a discrepancy in the magnitude of a comparison star used by various workers, and for a secular decline in the system's visual brightness of 0.021 mag/yr. Five different methods of period determination yield consistent results with a mean of 816.5 plus or minus 0.9 days, leading to an ephemeris for times of maximum visual light of (JD)max = 2442710.1 + 816.5E. A light curve based on normal points formed from the 89 individual observations is shown.
Adaptive multivlevel methods in three space dimensions

We consider the approximate solution of self-adjoint elliptic problems in three space dimensions by piecewise linear finite elements with respect to a highly non-uniform tetrahedral mesh which is generated adaptively. The arising linear systems are solved iteratively by the conjugate gradient method provided with a multilevel preconditioner. Here, the accuracy of the iterative solution is coupled with the discretization error. As the performance of hierarchical bases preconditioners deteriorates in three space dimensions, the BPX preconditioner is used, taking special care of an efficient implementation. Reliable a posteriori estimates for the discretization error are derived from a local comparison with the approximation resulting from piecewise quadratic elements. To illustrate the theoretical results, we consider a familiar model problem involving reentrant corners and a real-life problem arising from hyperthermia, a recent clinical method for cancer therapy.
Multimode image matching based on maximum similarity model and scale invariant feature transform for islands

Abstract. Different from the images of villages or towns where many homologous features can be extracted easily, the extraction of homologous features from multimode images located of sea islands is more difficult because the types of objects on sea islands are hard to recognize. When applying scale invariant feature transform (SIFT) to the image matching of sea islands, only sparsely matched couples with an uneven distribution are obtained. To resolve this problem, a new feature point matching method that combines a maximum similarity model and scale invariant feature transform (MS-SIFT) is proposed. This method can solve the primary difficulty of matching multimode images, which is to extract the massive feature points that are invariant to differences in spectrum, scale, and view angles between multimode images, and successfully obtain many precise matched couples of images located in areas with less remarkable features, especially for matching images of sea islands with less features. The application of the proposed algorithm shows that a large number of accurately matched couples could be identified. Additionally, the matched accuracy, space uniformity of the matched couples, and the running time computed based on the MS-SIFT and the traditional SIFT are analyzed and compared, which further demonstrate the effectiveness of the proposed algorithm.