Miracle-dz/UniFAR-FTUs huggingface dataset:
Structural analysis and aeroservoelastic response simulation of smart fin operated by piezoelectric actuators

In order to substitute a conventional fin operated by hydraulic actuators, a smart fin actuated by piezoelectric material was attempted. A straight unimorph actuator was embedded along the spanwise direction in the hollow inner space of the fin. A hinge which was constrained except the axial rotation was located at the 1/4th chord line, and this enabled the smart fin to rotate in its rigid pitch direction. In this paper, starting from the fundamental structural analysis, the aeroelastic and aeroservoelastic stability, and structural response simulations of the smart fin control system were performed by integration of MSC.NASTRAN, ZAERO and MATLAB/Simulink. The controller was designed to ensure the flight stability and to maintain the pitch angles of the smart fin under specific flight conditions. Closed-loop control system of the smart fin was constructed and analyzed by MATLAB/Simulink.
Speckle noise reduction for optical coherence tomography based on adaptive 2D dictionary

As a high-resolution biomedical imaging modality, optical coherence tomography (OCT) is widely used in medical sciences. However, OCT images often suffer from speckle noise, which can mask some important image information, and thus reduce the accuracy of clinical diagnosis. Taking full advantage of nonlocal self-similarity and adaptive 2D-dictionary-based sparse representation, in this work, a speckle noise reduction algorithm is proposed for despeckling OCT images. To reduce speckle noise while preserving local image features, similar nonlocal patches are first extracted from the noisy image and put into groups using a gamma- distribution-based block matching method. An adaptive 2D dictionary is then learned for each patch group. Unlike traditional vector-based sparse coding, we express each image patch by the linear combination of a few matrices. This image-to-matrix method can exploit the local correlation between pixels. Since each image patch might belong to several groups, the despeckled OCT image is finally obtained by aggregating all filtered image patches. The experimental results demonstrate the superior performance of the proposed method over other state-of-the-art despeckling methods, in terms of objective metrics and visual inspection.
Power deposition on misaligned castellated tungsten blocks in the Magnum-PSI and Pilot-PSI linear devices

For the final design of the ITER divertor it is important to determine whether shaping of each tungsten monoblock to eliminate leading edges is required or not. In order to aid this decision, two experiments were performed in DIFFER’s linear plasma devices to study heat loads on misaligned water cooled blocks at glancing incidence. First, a series of tungsten blocks were exposed to a high parallel heat flux (26 MW m−2) hydrogen plasma beam in the Magnum-PSI linear device. The blocks were exposed at an oblique angle between 4∘ and 7∘ with respect to the plasma beam, approaching the low angle of incidence expected in the ITER divertor strike-point regions. One block was vertically misaligned with respect to the others by a value between 0 and 1.2 mm, and the surface temperature evolution monitored. This was compared to a finite element thermo-mechanical model of the system, to investigate any discrepancies between the two. The importance of Larmor orbit smoothing effects could also be considered, as the Larmor radius was larger than half the misalignment height. Next, a row of identical tungsten blocks were exposed at an angle of 3∘ to ∼500–700 μs pulsed hydrogen plasmas of peak power between 275–625 MW m−2 in the Pilot-PSI linear device, to simulate the effect of edge localized mode (ELM) transients. One block was misaligned with respect to the others by 1 mm. In all cases, the model and experiment were found to be in excellent agreement (to ∼1%), demonstrating clearly that an optical approximation for plasma power loading on misaligned edges is appropriate. A simple model including Larmor smoothing was applied, the results of which give a similar prediction to the optical approximation for the temperature of the misaligned edges, within the error of the temperature measurements, though a small decrease in edge temperature is calculated. Therefore it can be concluded that the application of the optical approximation is generally appropriate as an input physics assumption for the study of shaping alternatives.
An efficient Monte Carlo simulation strategy based on model order reduction and artificial neural networks

In this paper, we present a new approach that enables the Monte Carlo simulation of complex nonlinear systems with considerably less computational effort compared to the classical Monte Carlo simulation. Hereby, we propose a combination of the proper orthogonal decomposition and neural networks. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Minimizing sensor movement in target coverage problem: A hybrid approach using Voronoi partition and swarm intelligence

This paper addresses the major challenges that reside on target coverage problem, which is one among the two primary sub-problems of node deployment problem. In order to accomplish a cost-efficient target coverage, a Voronoi partition-based, velocity added artificial bee colony algorithm (V-VABC) is introduced. The V-VABC is an advancement over the traditional, target-based Voronoi greedy algorithm (TV-greedy). Moreover, the VABC component of V-VABC is a hybrid, heuristic search algorithm developed from the context of ABC and particle swarm optimization (PSO). The V-VABC is an attempt to solve the network, which has an equal number of both sensors and targets, which is a special case of TCOV. Simulation results show that V-VABC performs better than TV-greedy and the classical and base algorithms of V-VABC such as ABC and PSO.
Design and realization of a grazing-incidence plane-grating monochromator

The design and realization of a plane-grating monochromator mainly intended for high-energy resolution in the extreme-ultraviolet and soft-X-ray spectral regions is presented. The principal application is the spectral selection of high-order laser harmonics generated in gas combined with the possibility to achieve sub-20-meV bandwidth, approaching synchrotron-like beamlines resolution performances. This geometry has three optical elements: a uniform-line-spaced plane grating illuminated by the converging light coming from a focusing cylindrical mirror and an additional plane mirror that is needed to change the grating subtended angle to keep the system in focus on a fixed slit. The parameters of the focusing mirror are determined to introduce a coma that compensates for the coma given by the grating. A monochromator for the 12-50 eV region has been realized to show the feasibility and the performances of the configuration.
Positivity Preservation in the Simulation of Relativistic Laser-Plasma Interaction

With standard schemes, the plasma density in the hydrodynamic model for relativistic laser-plasma interaction can become negative. Therefore, we present a new scheme that preserves the positivity of the plasma density while still satisfying the conservation of mass. The numerical results for a vacuum-plasma transition of a laser pulse in one and two dimensions compare very well to the results from a standard PIC code, but the computation time is greatly reduced.
On the Approximation of Vector Optimization Problems

В работе исследуются условия сходимости приближенного метода решения задач многокритериальной оптимизации, когда целевые функции и допустимое множество заменяются их приближениями. Доказано, что достаточным условием сходимости являются равномерная сходимость приближенных функций к исходной функции и сходимость допустимого множества приближенных задач к допустимому множеству исходной задачи, по крайней мере, в окрестности решения. Ключевые слова: векторная оптимизация, стохастическая многокритериальная оптимизация, парето-оптимальность, дискретная аппроксимация, эпсилон-доминирование. У роботі досліджено умови збіжності наближеного методу розв'язання задач багатокритеріальної оптимізації у випадку коли цільові функції і допустима область замінюються їх наближеннями. Доведено, що достатньою умовою збіжності є рівномірна збіжність наближених функцій до початкової функції та збіжність допустимої множини наближених задач до допустимої множини початкової задачі хоча б в околі розв ́язку. Ключові слова: векторна оптимізація, стохастична багатокритеріальна оптимізація, парето-оптимальність, дискретна апроксимація, епсілон-домінування.
The vector type Maxwell viscoelastic model and its relationship to thixotropy

Thixotropy is the rheological property of wide range of materials used in various industries. Great efforts from both industry and academy have been devoted to modelling thixotropy since it was experimentally observed about 90 years before by Schalek and Szegavri (1923), and numerous models, both empirical and theoretic, were proposed. The progress in the field are constantly summarized up to date, stage by stage, by the then review papers periodically appeared (Scott-Blair, 1943, Bauer and Collins, 1967, Mewis, 1979, Barnes, 1997, Mewis and Wagner, 2009). The approaches to modeling thixotropy were classified into viscous theory and viscoelastic theory (Barnes, 1997). In viscous theory the thixotropic fluid is considered as the pure viscous fluid but the viscosity changes with both shear rate (stress) and time, while in viscoelastic theory the thixotropic fluid is assumed to be viscoelastic. The viscous theory is further divided into three categories: direct microstructure, indirect microstructure theories, and continuum theory [5]. In both direct and indirect microstructure theories the thixotropic viscosity change is attributed to the breakdown and buildup of the structure of fluids during shear flow. Direct microstructure theory uses reaction kinetics to model the structure breakdown and buildup process (Goodeve, 1939, Storrey and Merrill, 1958, Cross, 1965, Ruchenstein and Mewis, 1973, Soong and Shen, 1981, De Kee and Chan Man Fong, 1994), while the indirect one describes the extent of the structure breakdown and buildup by introducing into a structure parameter which is unit for completely built-up structure and is zero for completely broken-down structure (Moore, 1959, Worrall and Tuliani, 1964, Cheng and Evans, 1965, Tiu and Boger, 1974, De Kee, Code and Turcotte, 1983, Nguyen and Boger, 1985, Toorman, 1997). Continuum theory is started by defining constitutive equation without understanding the physical process underlying (Slibar and Paslay, 1959, 1964, Elliott and Ganz, 1971, 1977, Suetsugu and White, 1984, Powell, 1995, Phan-Thien, Safari-Ardi, and Morales-Patino, 1997). In this paper a very different approach from all the existing ones, without introducing new rheological properties or assuming dependence of the viscosity or the elasticity on time or shear rate, will be attempted only by decoupling the second order tensors of the Maxwell viscoelastic model into vectors. The theoretical results will be compared with the
Cross-Sectional Study of Percentual Changes in Total Plasmatic Fatty Acids During Pregnancy

Total plasma fatty acids were analysed in 75 first trimester pregnant women, 32 second trimester pregnant women, 27 women at delivery and 38 non-pregnant women. Eleven fatty acids were studied by capillar gas chromatogra phy SP-column. Compared with non-pregnant women, in the first trimester there was a significant percentual increase in palmitic, palmitoleic, stearic and docosahexaenoic acids, whereas linoleic and eicosapentaenoic percentually decreased. Between the first and second trimester a signifi cant increase in the proportion of palmitic acid and a signif icant percentual decrease in arachidonic acid was detected. Between the second trimester and delivery the aforemen tioned changes were more marked. Between the second trimester and delivery there was also a significant percentual increase in oleic and linolenic acids, whereas the proportions of stearic, linoleic, dihomogammalinolenic and docosa hexaenoic acids significantly decreased. It is suggested that the intake in polyunsaturated fatty acids should be increased during pregnancy, specially in the third trimester.
Effect of scarfing on rectangular nozzle supersonic jet plume flow characteristics

An experimental and computational fluid dynamics study is reported of supersonic jets issuing from a high-aspect-ratio rectangular convergent–divergent nozzle with and without a scarfed exit. Schlieren visualization and laser Doppler anemometry measurements captured near-field aerodynamic development of an unheated jet at overexpanded, design, and underexpanded conditions. Reynolds-averaged Navier–Stokes computational fluid dynamics predictions using an eddy viscosity closure (Spalart–Allmaras model) for clean and scarfed geometries were compared with measurements to examine the ability to capture nozzle scarfing effects. The measured plume shape for a scarfed nozzle was strongly affected at overexpanded conditions (a distorted four-lobe shape was observed), whereas a rectangular shape was retained for underexpanded flow although plume bifurcation occurred. The development of the plume shape and the mixing rate was a consequence of the strong vortices that occur with rectangular nozzles, with extra vortic.
Compressed sensing reconstruction of hyperspectral images jointly using spatial smoothing feature and spectral correlation

A compressed sensing (CS) reconstruction algorithm of hyperspectral images jointly using spatial and spectral characteristics is considered. Specifically, in the sampling process, each band image is sampled by the block CS method independently. In the reconstruction process, how to utilize the spatial smoothing feature of each band image and spectral correlation between different band images to formulate the joint optimization problem is the focus of this paper. The total variation (TV) norm and multihypothesis prediction are introduced to express the spatial smoothing feature and the spectral correlation, respectively. Thus, the TV norm and the prediction residual are used as the regularization items in the reconstruction optimization problem. The resulting ill‐posed problem is solved by the augmented Lagrange multiplier method and alternating direction method in an iterative way, and the implementation process of the reconstruction algorithm is presented. Experimental results on four hyperspectral datasets reveal that the proposed algorithm significantly outperforms alternative strategies in terms of peak signal‐to‐noise ratio as well as visual quality. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Advances and Applications of Finite-Time Lyapunov Analysis

Many physical systems can be modeled through nonlinear time-invariant differential equations. When the dynamics of such systems are hyper-sensitive to the initial conditions, such equations are often challenging to solve. However, if the flow of such dynamical systems is also characterized by multiple timescales (e.g., fast-slow behavior), there may be a manifold structure associated with it. Focusing on this manifold structure, that is, adopting a geometric perspective, holds potential for a simpler solution process and a better understanding of the system behavior. We adopt finite-time Lyapunov analysis (FTLA) as the methodology to diagnose the timescalebehavior and to characterize the manifold structure. FTLA is based on finite-time Lyapunov exponents (FTLEs) and vectors (FTLVs) and its main advantage is that it is more widely applicable with respect to other methodologies. In fact, for nonlinear dynamical systems, FTLA is not restricted to equilibria nor periodic solutions, nor does it require require the equations to be in a special form. We will show that the accuracy of FTLA depends solely on how fast certain linear subspaces computed using FTLVs converge to their invariant counterparts. This work is dedicated to continuing the advancement of the methodology and to its applications to two-timescale partially hyperbolic dynamical systems. In the first part of this dissertation, we provide a detailed presentation of the methodology, with particular attention to the diagnosis of a uniform hyperbolic finite-time two-timescale set and to the computation of points on finite-time approximations of the invariant manifolds.The second and third parts of the dissertation focus entirely on the application of FTLA to two major problems. Firstly, we use FTLA as a means of computing the approximation of the local stable, center and unstable directions at points on orbits around libration points in the circular restricted three-body problem (CR3BP). After assessing the accuracy of the FTLA results for points on periodic orbits, where Floquet theory gives exact results, we move to aperiodic orbits, demonstrating that FTLA results maintain a degree of accuracy that is otherwise lost when applying Floquet theory in an approximate manner. Secondly, we propose a new stationkeeping strategy for spacecraft orbiting about libration points in the Earth-Moon CR3BP. The strategy is based on performing instantaneous velocity corrections that place the spacecraft on the stable manifold of some orbit in the neighborhood of a prescribed reference orbit. We demonstrate via several test cases that the proposed strategy is reliable and therefore can be considered as a good alternative or addition to existent stationkeeping strategies.In the last part, we focus our attention on developing a solution strategy for partially hyper-sensitive optimal control problems. The strategy exploits the existence of the invariant center-stable and center-unstable manifolds to construct an approximation to the optimal solution by matching trajectories on such…
Improved short‐term point and interval forecasts of the daily maximum tropospheric ozone levels via singular spectrum analysis

We propose a general method for producing reliable short‐term point and interval forecasts of daily maximum tropospheric ozone concentrations, a time series with a significant seasonal component and correlated errors in both mean and volatility. Our method combines symmetrizing data transformation and time series modeling techniques called the singular spectrum analysis and autoregressive models. Specifically, we transform the underlying distribution of the data to a symmetric distribution by applying the log and Yeo–Johnson transformation for accurate positive point forecasts. Moreover, we consider seasonality in both the mean and volatility of the time series, as well as empirical quantile estimation, for better interval forecasts. The accuracy of the proposed method is verified rigorously at selected sites in the United States with differing latitudes, geography, and degrees of anthropogenic activities. The results indicate that the proposed method seems to outperform the standard method that does not consider data transformation and seasonality in volatility.
Photon Gas Is the Medium of Electromagnetic Waves

The aim of this paper is to find the carrier or medium of electromagnetic waves that has been searched for many years. The thermal radiation is composed of the shot noise and the wave noise, so the Planck formula can be separated mathematically into two parts. Assume every photon has the same proper magnetic moment and an equal rest mass which has been estimated from the cosmic background temperature in space where the photon gas is at an open state of thermal equilibrium. The magnetic-electric dynamic equation is established that means magnetic curl caused electric change, and the electric-magnetic dynamic equation is established that means electric curl caused magnetic change. After the wave equation is caught, it is clear that the photon gas is the medium of electromagnetic waves in vacuum.
Dual Quaternion-Based Powered Descent Guidance with State-Triggered Constraints

This paper presents a numerical algorithm for computing 6-degree-of-freedom free-final-time powered descent guidance trajectories. The trajectory generation problem is formulated using a unit dual quaternion representation of the rigid body dynamics, and several standard path constraints. Our formulation also includes a special line of sight constraints that is enforced only within a specified band of slant ranges relative to the landing site, a novel feature that is especially relevant to Terrain and Hazard Relative Navigation. We use the newly introduced state-triggered constraints to formulate these range constraints in a manner that is amenable to real-time implementations. The resulting non-convex optimal control problem is solved iteratively as a sequence of convex second-order cone programs that locally approximate the non-convex problem. Each second-order cone program is solved using a customizable interior point method solver. Also introduced are a scaling method and a new heuristic technique that guide the convergence process towards dynamic feasibility. To demonstrate the capabilities of our algorithm, two numerical case studies are presented. The first studies the effect of including a slant-range-triggered line of sight constraint on the resulting trajectories. The second study performs a Monte Carlo analysis to assess the algorithm's robustness to initial conditions and real-time performance.
Initial development of a free-surface wall jet at moderate Reynolds number

The steady laminar flow of a moderately inertial wall jet is examined theoretically near the exit of a channel. The free-surface jet emerges asymmetrically from the channel as it adheres to an infinite (upper) wall subject to a pressure gradient. The problem is solved using the method of matched asymptotic expansions. The small parameter involved in the expansions is the inverse cubic power of the Reynolds number. The flow field is obtained by matching the inviscid rotational core flow separately with the free-surface and the two wall layers. The upstream influence is examined as well as the break in the symmetry between the two wall layers. The wall jet exhibits a contraction near the channel exit that is independent of inertia, and eventually expands for any Reynolds number. Unlike the flow of a wall jet emerging into the same ambient fluid, the free-surface jet experiences a limited weakening in shear stress along the infinite wall, suggesting the possibility of separation for a jet with relatively low inertia. Significant shearing and elongation ensue at the exit, accompanied by flattening of the velocity profile near the upper wall.
Depth extraction of low-texture region using a light field camera

Abstract. A method is proposed for depth extraction of low-texture region with a light field (LF) camera, which expands the application. Based on the analysis of LF data, it is proven that the depth information can be estimated from a single LF image. Furthermore, as the lenslet LF data can be decoded into a subimages array, and the relationship among subimages is proven to be affine transformation, we used the geometry relationship, which is represented by partition ratio of triangle grids area, to replace the unreliable gray value of low-texture region for stereo matching. In addition, to obtain accurate ratio values, preset points are projected to enrich the texture with a projector, which is convenient and reliable. The proposed method improves the accuracy of the depth extraction obviously at low-texture region compared with the traditional state-of-the-art LF method, and results are validated by experiments.