Miracle-dz/UniFAR-FTUs huggingface dataset:
Error bounds for Approximations of Markov chains

The first part of this article gives error bounds for approximations of Markov kernels under Foster-Lyapunov conditions. The basic idea is that when both the approximating kernel and the original kernel satisfy a Foster-Lyapunov condition, the long-time dynamics of the two chains -- as well as the invariant measures, when they exist -- will be close in a weighted total variation norm, provided that the approximation is sufficiently accurate. The required accuracy depends in part on the Lyapunov function, with more stable chains being more tolerant of approximation error. We are motivated by the recent growth in proposals for scaling Markov chain Monte Carlo algorithms to large datasets by defining an approximating kernel that is faster to sample from. Many of these proposals use only a small subset of the data points to construct the transition kernel, and we consider an application to this class of approximating kernel. We also consider applications to distribution approximations in Gibbs sampling. Another application in which approximating kernels are commonly used is in Metropolis algorithms for Gaussian process models common in spatial statistics and nonparametric regression. In this setting, there are typically two sources of approximation error: discretization error and approximation of Metropolis acceptance ratios. Because the approximating kernel is obtained by discretizing the state space, it is singular with respect to the exact kernel. To analyze this application, we give additional results in Wasserstein metrics in contrast to the proceeding examples which quantified the level of approximation in a total variation norm.
Cloud Computing Migration Barriers and Advantages in Manufacturing – an Analysis of Ambiguity and Dependences in the Assessment Criteria

Abstract There is still many misunderstandings associated with the assessment of the barriers encountered in the process of IT solutions migration to the computational cloud and the benefits to be expected. The purpose of this paper is to organize the criteria used in this field, to analyze the dependencies between them. This will allow us to better understand the problem of migration to the cloud and to improve the decision-making processes related to it. A comprehensive survey was carried out, covering about 400 manufacturing enterprises in Poland using cloud-based IT solutions in various areas. The elements of the study were questions about the barriers and benefits encountered in this process. The paper analyzes the relationships between the obtained categories using diverse data mining methods: association rules mining and hierarchical agglomerative clustering. The obtained results allow to identify the conceptual structure and build a model of relationships inside the problem.
Incoherent Scatter Spectra Based On Monte Carlo Simulations of Ion Velocity Distributions Under Strong Ion Frictional Heating

Under strong electric field conditions often found at high latitudes, the ion velocity distribution of the weakly ionized F region plasma can differ enough from a Maxwellian shape to substantially change incoherent scatter (IS) spectra and thus the analysis of those spectra. With the goal to provide a quantitative and reliable description of the IS spectra, this study directly uses for the first time an advanced Monte Carlo calculation of the ion velocity distribution to derive IS spectra for a range of electric fields and aspect angles. For most cases the spectra associated with NO+ maintains a shape that closely resembles that of a spectrum derived from a Maxwellian distribution with the same line‐of‐sight ion temperature as the equivalent Monte Carlo simulated distribution. This study also fully characterizes the spectral shape as well as the ion temperature and its anisotropy for two different models of the resonant charge exchange between O+ and O. It confirms that the distortions from the Maxwellian shape can be substantial for this particular interaction. The distortions are also such that along the magnetic field direction, the extracted apparent electron temperature is always greater than the real temperature. This work also includes a determination of the stability of the plasma against magnetic field‐aligned electrostatic instabilities. It is found that the NO+ distribution is always stable, whereas the O+ distribution may or may not be stable, depending on the model chosen for the resonant charge exchange cross section in collisions with the background atomic oxygen gas.
Robust feedback control of flow separation using plasma actuators

This thesis addresses the problem of controlling the unsteady flow separation over an aerofoil using plasma actuators, with the aim of improving the performance of fluid systems through the use of robust feedback controllers. Despite the complexity of the dynamics of interest, it is shown how the problem of controlling flow separation can be successfully formulated and solved as a simple output regulation problem. First, a novel control-oriented reduced-order model for nonlinear systems evolving on attractors is obtained. Its application to the incompressible Navier-Stokes equations is proposed, in order to obtain a linear reduced-order model (whose state variables have a clear and consistent physical meaning) of the complex flow/actuator dynamics. On the basis of the proposed model, a new robust multivariable feedback control algorithm for flow separation suppression is designed, using real-time velocity measurements, which are available in realistic applications. The presented control scheme is tested in both Single-Input-Single-Output (SISO) and Multi-Input-Multi-Output (MIMO) configurations, thus allowing for optimising the closed-loop system, with the aim of selecting suitable numbers and positions of the actuator/sensor pairs along the aerofoil, as well as desired references for the real-time measurements, according to the specific application (e.g., flow separation suppression, mixing enhancement etc.). Accurate numerical simulations of incompressible flows around both 2D aerofoils and 3D wings are performed in order to optimise the closed-loop system and illustrate the effectiveness of the proposed approach in the presence of complex dynamics that are neglected at the design stage. Robust performances, with respect to both parameter variations (e.g. geometry of the domain and Reynolds number) and model uncertainties, are demonstrated. The designed controller is able to effectively suppress the flow separation along the aerofoil, as well as the shedding vortices, thus yielding both a reduction of the drag and an increase of the lift. This allows for stall avoidance and increased efficiency.
Finding branch-decomposition and rank-decomposition

We present a new algorithm that can output the rank-decomposition of width at most $k$ of a graph if such exists. For that we use an algorithm that, for an input matroid represented over a fixed finite field, outputs its branch-decomposition of width at most $k$ if such exists. This algorithm works also for partitioned matroids. Both these algorithms are fixed-parameter tractable, that is, they run in time $O(n^3)$ for each fixed value of $k$ where $n$ is the number of vertices / elements of the input.
Intravascular Ultrasound Elastography

Summary. Intravascular Ultrasound Blastography. The re sponse of a tissue to mechanical excitation is a function of its mechanical properties. Excitation can be dynamic or quasistatic in nature. The response (e.g. displacement, velocity, compres sion) can be measured via ultrasound. This is the main principle underlying ultrasound elasticity imaging, sonoelasticity imag ing, or ultrasound elastography. It is of great interest to know the local hardness of vessel wall and plaques. Intravascular elastography yields information unavailable or inconclusive if obtained from IVUS alone and thus contributes to more correct diagnosis. Potentially it can be used for therapy guidance. During the last decade several working groups used elastogra phy in intravascular applications with varying success. In this paper we discuss the various approaches by different working groups. Focus will be on the approach of the Rotterdam group. Using a 30 MHz IVUS catheter, RF data are acquired from ves sels in vitro at different intraluminal pressures. Local tissue dis placement estimation by cross-correlation is followed by com putation of the local strain. The resulting image supplies local information on the elastic properties of the vessel and plaque with high spatial resolution. Feasibility and usefulness are shown by means of phantom mesurements. Furthermore, ini tial in vitro results of femoral arteries and correlation with histology are discussed. Phantom data show that the elasto grams reveal information not presented by the echogram. In vitro artery data prove that in principle elastography is capable of identifying plaque composition where echography fails.
A space-time discontinuous Galerkin spectral element method for the Stefan problem

A novel space-time discontinuous Galerkin (DG) spectral element method is presented to solve the one dimensional Stefan problem in an Eulerian coordinate system. This method employs the level set procedure to describe the time-evolving interface. To deal with the prior unknown interface, a backward transformation and a forward transformation are introduced in the space-time mesh. By combining an Eulerian description, i.e., a fixed frame of reference, with a Lagrangian description, i.e., a moving frame of reference, the issue of dealing with implicitly defined arbitrary shaped space-time elements is avoided. The backward transformation maps the unknown time-varying interface in the fixed frame of reference to a known stationary interface in the moving frame of reference. In the moving frame of reference, the transformed governing equations, written in the space-time framework, are discretized by a DG spectral element method in each space-time slab. The forward transformation is used to update the level set function and then to project the solution in each phase back from the moving frame of reference to the fixed Eulerian grid. Two options for calculating the interface velocity are presented, and both options exhibit spectral accuracy. Benchmark tests indicate that the method converges with spectral accuracy in both space and time for the temperature distribution and the interface velocity. A Picard iteration algorithm is introduced in order to solve the nonlinear algebraic system of equations and it is found that just a few iterations lead to convergence.
Design of A New Structure Quartz MEMS Gyroscope with High Sensitivity

This paper proposes a new structure of quartz MEMS gyroscope. Compared with the traditional double-ended quartz gyroscope, the grooves are symmetrically arranged in the sense tuning forks of new gyroscope, and the two pairs of extra electrodes are added on the grooves. The extra symmetrical sense electrodes can increase the strong electric field, and the increased area of sense electrodes is beneficial to detect charge signals. The ANSYS finite element software is used to simulate the designed structure. The influence of frequency difference is analyzed by modal type, and the parameters of quartz tuning fork gyroscope are optimized to find the suitable structure, the frequency difference of the gyroscope is 203.42Hz. At the same time, the sensitivity is analyzed by harmonic type. The results show that the increasing of the area electrode is efficient, the efficiency of electric field detection is enhanced. The sensitivity of the quartz MEMS gyroscope is increased by more than 15%.
Evaluation de la précision des algorithmes de projection affine en virgule fixe

The aim of this paper is to determine an analytical expression of the noise power generated by a fixed-point implementation of Affine Projection Algorithms (APA). These algorithms were developed 20 years ago but no study has been made about its fixed-point implementation. In this paper, an analytical expression of the noise power is defined and applied to the NLMS-OCF algorithm (an Affine Projection Algorithm). The model accuracy is verified by simulations.
Adaptive pixel-to-pixel projection intensity adjustment for measuring a shiny surface using orthogonal color fringe pattern projection

Three-dimensional (3D) shape measurement based on fringe pattern projection techniques has been commonly used in various fields. One of the remaining challenges in fringe pattern projection is that camera sensor saturation may occur if there is a large range of reflectivity variation across the surface that causes measurement errors. To overcome this problem, a novel fringe pattern projection method is proposed to avoid image saturation and maintain high-intensity modulation for measuring shiny surfaces by adaptively adjusting the pixel-to-pixel projection intensity according to the surface reflectivity. First, three sets of orthogonal color fringe patterns and a sequence of uniform gray-level patterns with different gray levels are projected onto a measured surface by a projector. The patterns are deformed with respect to the object surface and captured by a camera from a different viewpoint. Subsequently, the optimal projection intensity at each pixel is determined by fusing different gray levels and transforming the camera pixel coordinate system into the projector pixel coordinate system. Finally, the adapted fringe patterns are created and used for 3D shape measurement. Experimental results on a flat checkerboard and shiny objects demonstrate that the proposed method can measure shiny surfaces with high accuracy.
HOLOGRAPHIC, MOTION-INI)UCED-CONTRAST IMAGES

Holography is an optical technique for reconstructing the wave which is scattered by an object (1-4). The reconstruction of an object-scattered wave provides a three-dimensional image retaining the amplitude-attenuating and phase-retarding properties of the object. Holographic images have unique properties which are useful in biological research. A hologram is made by illuminating an object with a coherent wave and then by recording the object-scattered wave and a superimposed, coherent, reference wave. The recording, usually a photograph, contains an interference pattern whose exact form depends upon the phase and amplitude of the object-scattered wave. Thus, phase and intensity are recorded in the hologram. To reconstruct the object-scattered wave, the developed hologram is placed in a coherent beam. The recorded interference pattern acts as a highly complex diffraction grating and diffracts the illuminating beam into a zero-order and two firstorder beams. The first-order beams each contain a high-quality, three-dimensional image. Since image formation depends on diffraction
Thickness effects on the epitaxial strain states and phase transformations in (001)-VO2/TiO2 thin films

The thickness-dependent epitaxial strains and phase transformations of (001)-VO2/TiO2 thin films are investigated systematically in a wide thickness range (from 9 to 150 nm). Under a thickness of 18 nm, the tensile in-plane strain is maintained, owing to the good lattice and the symmetry matching between the VO2 thin film and the TiO2 substrate, but the compressive out-of-plane epitaxial strain is gradually relaxed. The epitaxial strains co-stabilize the rutile phase (R phase) in this thickness range. Beyond a thickness of 18 nm, the out-of-plane lattice c exhibits a sudden elongation and reaches the bulk level of 2.8528 A at a thickness of 20 nm, which indicates a structural phase transition (SPT). A further increase of the film thickness results in another new phase (tetragonal-like or T-like) with lattice distortion, which maintains the tetragonal symmetry in the thickness range of 20 to 55 nm. From a thickness of 60 nm, the monoclinic phase (M1 phase) appears, which indicates another SPT from T-like to the monoclinic M1 phase. This SPT is more favorable energetically, owing to the assistance of the strain relaxation in the thicker films. Additionally, the metal-insulator transition temperature positively increases as a function of the out-of-plane strain. This result is consistent with the fact that the tensile strain along the cR axis (V-V atom chain) is conducive for the stabilized insulating phase. This work highlights strain engineering as a crucial avenue for manipulating the phase transformations and properties in the correlated electron system.The thickness-dependent epitaxial strains and phase transformations of (001)-VO2/TiO2 thin films are investigated systematically in a wide thickness range (from 9 to 150 nm). Under a thickness of 18 nm, the tensile in-plane strain is maintained, owing to the good lattice and the symmetry matching between the VO2 thin film and the TiO2 substrate, but the compressive out-of-plane epitaxial strain is gradually relaxed. The epitaxial strains co-stabilize the rutile phase (R phase) in this thickness range. Beyond a thickness of 18 nm, the out-of-plane lattice c exhibits a sudden elongation and reaches the bulk level of 2.8528 A at a thickness of 20 nm, which indicates a structural phase transition (SPT). A further increase of the film thickness results in another new phase (tetragonal-like or T-like) with lattice distortion, which maintains the tetragonal symmetry in the thickness range of 20 to 55 nm. From a thickness of 60 nm, the monoclinic phase (M1 phase) appears, which indicates another SPT from T-like t.
A connection between time domain model order reduction and moment matching for LTI systems

ABSTRACT We investigate the time domain model order reduction (MOR) framework using general orthogonal polynomials by Jiang and Chen [1] and extend their idea by exploiting the structure of the corresponding linear system of equations. Identifying an equivalent Sylvester equation, we show a connection to a rational Krylov subspace, and thus to moment matching. This theoretical link between the MOR techniques is illustrated by three numerical examples. For linear time-invariant systems, the link also motivates that the time-domain approach can be at best as accurate as moment matching, since the expansion points are fixed by the choice of the polynomial basis, while in moment matching they can be adapted to the system.
Simulation of a 3D Turbulent Wavy Channel based on the High-order WENO Scheme

Passive interest turbulent drag reduction, effective means to improve air vehicle fuel consumption costs. Most turbulent problems happening to the nature and engineering applications were exactly the turbulence problem frequently caused by one or more turbulent shear flows. This study was operated with incompressible 3-D channels with cyclic wavy boundary to explore the physical properties of turbulence flow. This research measures the distribution of average velocity, instant flowing field shapes, turbulence and pressure distribution, etc. Furthermore, the systematic computation and analysis for the 3-D flow field was also implemented. It was aimed to clearly understand the turbulence fields formed by wavy boundary of tube flow. The purpose of this research is to obtain systematic structural information about the turbulent flow field and features of the turbulence structure are discussed.
BEYOND THE FRAUD TRIANGLE; WHY PEOPLE ENGAGE IN PECUNIARY CRIMES?

Introduction:Research on fraud in accounting is firmly placed in the context of auditing which emphasises audit risk and the role of auditing and internal controls in the prevention and detection of fraud (Asare and Wright, 2004; Bierstaker, et al., 2006; Moyes and Baker, 2003; Patterson and Noel, 2003; Payne and Ramsay, 2005; Pinkus, 1989; Ramos, 2003). Research that examines the practice and effectiveness of fraud prevention and detection is premised on the auditor‘s obligation to detect materially misstated financial statements. However they do not realize that a study of factors relating to pecuniary crimes is the most important things in fraud detection (Maulidi, 2016). Thus, this paper will analyse them in a difference way beyond fraud triangle as proposed by Donald Cressy (1950).
Geodetic analysis of disputed accurate qibla direction

Abstract Muslims perform the prayers facing towards the correct qibla direction would be the only one of the practical issues in linking theoretical studies with practice. The concept of facing towards the Kaaba in Mecca during the prayers has long been the source of controversy among the muslim communities to not only in poor and developing countries but also in developed countries. The aims of this study were to analyse the geodetic azimuths of qibla calculated using three different models of the Earth. The use of ellipsoidal model of the Earth could be the best method for determining the accurate direction of Kaaba from anywhere on the Earth’s surface. A muslim cannot direct himself towards the qibla correctly if he cannot see the Kaaba due to setting out process and certain motions during the prayer this can significantly shift the qibla direction from the actual position of the Kaaba. The requirement of muslim prayed facing towards the Kaaba is more as spiritual prerequisite rather than physical evidence.
Weibull-type speckle distributions as a result of saturation in stimulated scattering processes

During the propagation of an optically smoothed laser beam through a warm plasma the speckle field pattern and the corresponding speckle intensity distribution are modified in time and along the laser propagation direction. It is shown here that the laser–plasma interaction can change the character of speckle statistics from an initially exponential-type limit law to a Weibull-type law. The Weibull distribution is characterized by a power-law-type behavior in a limited interval of the random variable, which is, in the present case, the speckle intensity. The properties of the speckle distributions are studied using methods of extremal and order statistics. The scattering instability process (here stimulated Brillouin forward scattering) causing the change in speckle statistics has an onset behavior associated with a “critical gain” value, as pointed out in work by Rose and DuBois (1993b). The saturation of the instability process as a function of intensity explains the limited interval of the Weibull-type speckle distribution. The differences in the type of the speckle statistics are analyzed by using “excess over threshold” methods relying on the generalized Pareto distribution, which clearly brings to evidence the transition from an exponential type distribution to the Weibull-type distribution as a function of the instability gain value, that is, from the regime below critical gain to values above the critical gain.
A Matlab user-interface tool for modelling herds

Animal flocks, schools, and herds are iconic examples of agent-based complex systems. Individual animals interact with each other in ways we can model on a computer, with group properties emerging under certain conditions. In this paper we provide a Matlab-based user-interface tool (UI) that allows users to model herds with two prominent algorithms—the Voronoi and Local Crowded Horizon attraction models—in environments with and without predators. This UI also allows the user to include random animal motion (or noise) with the herding algorithms, which can facilitate herd cohesion and lower predation risk. Our UI is well suited for the teaching of complex systems, allowing students and those new to the field to build an intuition on how group behaviour can emerge from individual interactions. Ultimately, relating simulation results to observations of animals in nature helps refine our models and improve our understanding of these biological systems.