Miracle-dz/UniFAR-FTUs huggingface dataset:
Advances and applications of the digital mask technique in particle image velocimetry experiments

Some advancements of the digital mask technique, which was first described by Gui and Merzkirch (1996a ERCOFTAC Bull. 30 45–8) for a phase-separated evaluation of two-phase flow particle image velocimetry (PIV) recordings, are presented in this paper. The originally minimum-quadratic-difference- (MQD-) based mask technique is accelerated by using the fast Fourier transformation algorithm. In order to further increase the evaluation speed and the measurement accuracy, the digital mask technique is modified so that it can be combined with the correlation-based central difference image correction (CDIC) method, which is proved to be a more accurate and less peak-locked evaluation algorithm than both the MQD tracking method and the correlation-based tracking method. An ellipse-shaped interrogation window is constructed with the digital mask technique to improve the spatial resolution of the evaluation without loss of the evaluation accuracy. Applications in PIV measurements of solid/water two-phase flow, bubbly water flow, flow around a human blood cell and airflow near the tip of a vibrating cantilever demonstrate that the combination of the digital mask technique, the CDIC algorithm and the ellipse interrogation window makes a powerful tool for evaluating digital PIV recordings of complex flows.
ELM-free stationary H-mode plasmas in the ASDEX Upgrade tokamak

ELM-free H-mode plasmas with stationary plasma density and radiation level are obtained in the ASDEX Upgrade tokamak with large clearance between the last closed flux surface and the wall, and neutral beam injection in a toroidal direction opposite to that of the plasma current. This behaviour is accompanied by a characteristic narrow-band magnetohydrodynamic (MHD) oscillation with clear harmonics up to n = 11 visible. This mode is localized in the plasma edge region. Conditions and properties of the stationary ELM-free phases and the edge MHD oscillation closely resemble that of the `quiescent H-mode' and the `edge harmonic oscillation' found in the DIII-D tokamak (Burrell K H et al 2002 Plasma Phys. Control. Fusion 44 A253). In addition, high-frequency MHD oscillations are found with an amplitude correlated with fluctuations of the divertor Dα intensity, suggesting a possible relevance of these modes for particle transport.
Resonant Analysis of Magnetic Coupling Wireless Power Transfer Systems

For a general multi-coil magnetic coupling wireless power transfer (MC-WPT) system with different coil properties and non-negligible cross couplings, there is no analytical solution that connects the resonant frequencies of the system to its electric parameters. Establishing such a generalized analytical solution not only permits quantitative analysis of resonant points but also provides a generic platform for the physical interpretation of resonance. For this purpose, a novel modeling and analysis method of integrating time domain and frequency domain is proposed in this paper, with that all possible resonant points of arbitrary coil MC-WPT systems can be quickly and accurately determined. First, an accurate state-space model of a general MC-WPT system with arbitrary number of transmitters, repeaters, and receivers is established and the analytical current response on each circuit is derived. Then, several key system concepts about resonance are elucidated, based on which the generalized analytical expressions of resonant points of MC-WPT systems, including resonant frequencies and corresponding powers and efficiencies, are derived. Furthermore, the physical interpretation along with the mathematic relationships of several key easy-confusing concepts are deduced, which provides a systematic theoretical criteria for the selection of operating frequency to achieve the resonant states for MC-WPT systems.
Efficient structural analysis of gas turbine blades

Purpose The purpose of this study a fast procedure for the structural analysis of gas turbine blades in aircraft engines. In this connection, investigations on the behavior of gas turbine blades concentrate on the analysis and evaluation of starting dynamics and fatigue strength. Besides, the influence of structural mistuning on the vibration characteristics of the single blade is analyzed and discussed. Design/methodology/approach A basic computation cycle is generated from a flight profile to describe the operating history of the gas turbine blade properly. Within an approximation approach for high-frequency vibrations, maximum vibration amplitudes are computed by superposition of stationary frequency responses by means of weighting functions. In addition, a two-way coupling approach determines the influence of structural mistuning on the vibration of a single blade. Fatigue strength of gas turbine blades is analyzed with a semi-analytical approach. The progressive damage analysis is based on MINER’s damage accumulation assuming a quasi-stable behavior of the structure. Findings The application to a gas turbine blade shows the computational capabilities of the approach presented. Structural characteristics are obtained by robust and stable computations using a detailed finite element model considering different load conditions. A high quality of results is realized while reducing the numerical costs significantly. Research limitations/implications The method used for analyzing the starting dynamics is based on the assumption of a quasi-static state. For structures with a sufficiently high stiffness, such as the gas turbine blades in the present work, this procedure is justified. The fatigue damage approach relies on the existence of a quasi-stable cyclic stress condition, which in general occurs for isotropic materials, as is the case for gas turbine blades. Practical implications Owing to the use of efficient analysis methods, a fast evaluation of the gas turbine blade within a stochastic analysis is feasible. Originality/value The fast numerical methods and the use of the full finite element model enable performing a structural analysis of any blade structure with a high quality of results.
Early dark energy at high redshifts: status and perspectives

Early dark energy models, for which the contribution to the dark energy density at high redshifts is not negligible, influence the growth of cosmic structures and could leave observable signatures that are different from the standard cosmological constant cold dark matter (ΛCDM) model. In this paper, we present updated constraints on early dark energy using geometrical and dynamical probes. From WMAP five-year data, baryon acoustic oscillations and type Ia supernovae luminosity distances, we obtain an upper limit of the dark energy density at the last scattering surface (lss), ΩEDE(zlss) < 2.3 × 10−2 (95% C.L.). When we include higher redshift observational probes, such as measurements of the linear growth factors, Gamma-Ray Bursts (GRBs) and Lyman-α forest (Lyα), this limit improves significantly and becomes ΩEDE(zlss) < 1.4 × 10−3 (95% C.L.). Furthermore, we find that future measurements, based on the Alcock-Paczyński test using the 21cm neutral hydrogen line, on GRBs and on the Lyα forest, could constrain the behavior of the dark energy component and distinguish at a high confidence level between early dark energy models and pure ΛCDM. In this case, the constraints on the amount of early dark energy at the last scattering surface improve by a factor ten, when compared to present constraints. We also discuss the impact on the parameter γ, the growth rate index, which describes the growth of structures in standard and in modified gravity models.
Velocity Transfer Spectroscopy of Rb 420 nm Transition

We propose and demonstrate the velocity transfer spectroscopy of a V-type energy structure with Rb atoms at 420 nm transition. The weak oscillator strength of a lower excited state for V-type energy structure atoms limits the high signal-to-noise ratio of atomic laser spectroscopy, which can be usually realized by optical-optical double-resonance or double-resonance optical pumping for cascade-type energy structure atoms. For 87Rb atoms, the weak 420 nm transition spectrum between the energy level of 52 S1/2 and 62 P3/2 is transferred to the spectrum on lower excited states at 780 nm with strong oscillator strength, which is recorded by a 780 nm probe laser. This method, which is similar to the electron-shelving detection method, at a certain degree can indirectly measure a higher excited state transition with weak oscillator strength for any V-type energy structure of atoms by transferring the transition spectrum information of the very weak oscillator strength to the strong oscillator strength in an optical-optical double-resonance configuration.
Backtracking Algorithm for Single-Axis Solar Trackers installed in a sloping field

In this paper we present a backtracking algorithm that improves the energy production of a single-axis solar tracker by reducing the shadow caused by neighboring panels. Moreover, the proposed algorithm can operate in any field slope avoiding the necessity of correcting the field slope where the solar tracker is placed. This is an important feature once it will reduced the time and the manpower during the solar tracker setup. The results have shown that the algorithm presents a similar performance comparing to similar algorithms that were designed only for horizontal fields.
FreeStyle Libre Flash Glucose Self-Monitoring System: A Single-Technology Assessment

Diabetes – both type 1 and type 2 – demands a very high level of self-management, probably more than any other disease. Diabetes affects the patient’s life continuously – and vice versa. Multiple factors has an influence, and the patient has to monitor the blood glucose level several times a day, to try and keep it stable enough to avoid hypoor hyperglycemias and low enough to prevent a raised HbA1c-level. For most persons with diabetes this can be a very challenging task, regardless of the duration of the disease. According to the two diabetes registries in Norway, the majority of people with type 1 fail to reach their treatment targets.
Adaptive Boundary Control Using Natural Switching Surfaces for Flyback Converters Operating in the Boundary Conduction Mode with Parameter Uncertainties

The derivation and implementation of the natural switching surfaces (NSS) considering certain parametric uncertainties for a flyback converter operating in the boundary conduction mode is the main focus of this paper. The NSS with nominal parameters presents many benefits for the control of nonlinear systems; for example, fast transient response under load-changing conditions. However, the performance worsens considerably when the converter actual parameters are different from the ones used in the design process. Therefore, a novel control strategy for NSS considering the effects of parameter uncertainties is proposed. This control law can estimate and adapt the control trajectories in a minimum number of switching cycles to obtain excellent performances even under extreme parameter uncertainties. The analytical derivation of the proposed adaptive switching surfaces is presented together with simulations and experimental results showing adequate performance under different tests, including comparisons with a standard PI controller.
Waste production classification and analysis: a PCA-induced methodology

District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. The main scope of this paper is to assess the feasibility of using the heat demand – outdoor temperature function for heat demand forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations.
Magnetic materials for MEMS applications

This topical review discusses magnetic microelectromechanical systems (MagMEMS). A number of exemplars are drawn from the authors' own work, and a review is given of other significant literature in the area. The case is made that MagMEMS offer unique features over conventional MEMS, such as remote interrogation and self-test. A review of the key magnetic principles and magnetic materials is included by way of a guide to the general reader. Finally, a roadmap for the future development of MagMEMS is set out.
Testing a phenomenologically extended DGP model with upcoming weak lensing surveys

A phenomenological extension of the well-known brane-world cosmology of Dvali, Gabadadze and Porrati (eDGP) has recently been proposed. In this model, a cosmological-constant-like term is explicitly present as a non-vanishing tension σ on the brane, and an extra parameter α tunes the cross-over scale rc, the scale at which higher dimensional gravity effects become non negligible. Since the Hubble parameter in this cosmology reproduces the same ΛCDM expansion history, we study how upcoming weak lensing surveys, such as Euclid and DES (Dark Energy Survey), can confirm or rule out this class of models. We perform Monte Carlo Markov Chain simulations to determine the parameters of the model, using Type Ia Supernovæ, H(z) data, Gamma Ray Bursts and Baryon Acoustic Oscillations. We also fit the power spectrum of the temperature anisotropies of the Cosmic Microwave Background to obtain the correct normalisation for the density perturbation power spectrum. Then, we compute the matter and the cosmic shear power spectra, both in the linear and non-linear régimes. The latter is calculated with the two different approaches of Hu and Sawicki (2007) (HS) and Khoury and Wyman (2009) (KW). With the eDGP parameters coming from the Markov Chains, KW reproduces the ΛCDM matter power spectrum at both linear and non-linear scales and the ΛCDM and eDGP shear signals are degenerate. This result does not hold with the HS prescription. Indeed, Euclid can distinguish the eDGP model from ΛCDM because their expected power spectra roughly differ by the 3σ uncertainty in the angular scale range 700≲ℓ≲3000; on the contrary, the two models differ at most by the 1σ uncertainty over the range 500≲ℓ≲3000 in the DES experiment and they are virtually indistinguishable.
3-D Printed Fabry–Pérot Resonator Antenna with Paraboloid-Shape Superstrate for Wide Gain Bandwidth

A three-dimensional (3-D) printed Fabry–Perot resonator antenna (FPRA), which designed with a paraboloid-shape superstrate for wide gain bandwidth is proposed. In comparison with the commonly-adopted planar superstrate, the paraboloid-shape superstrate is able to provide multiple resonant heights and thus satisfy the resonant condition of the FPRA in a wide frequency band. A FPRA working at 6 GHz is designed, fabricated, and tested. Considering the fabrication difficulty caused by its complex structure, the prototype antenna was fabricated by using the 3-D printing technology, i.e., all components of the prototype antenna were printed with photopolymer resin and then treated by the surface metallization process. Measurement results agree well with the simulation results, and show the 3-D printed FPRA has a |S11| < −10 dB impedance bandwidth of 12.4%, and a gain of 16.8 dBi at its working frequency of 6 GHz. Moreover, in comparison with the planar superstrate adopted in traditional FPRAs, the paraboloid-shape superstrate of the proposed FPRA significantly improves the 3-dB gain bandwidth from 6% to 22.2%.
Fabrication of a micromachined optical modulator using the CMOS process

This paper presents a new micromachined optical modulator design with electrostatic actuation fabricated by the conventional complementary metal-oxide semiconductor (CMOS) process. The modulator is operated by the interaction of the fixed part, stationary gratings and the movable part, sliding gratings. The period of the gratings varies with the slide of the movable part, thereby allowing different diffraction patterns of the reflected light. In addition, 100% modulation in the first order can serve as an optical switch. All procedures following the CMOS process merely require a simple post-process with maskless etching. With different profiles of the shape and sacrificial layer, two types of modulator are developed to obtain a high-aspect ratio and high efficiency of modulation, respectively.
Pixel-Level Cracking Detection on 3D Asphalt Pavement Images Through Deep-Learning- Based CrackNet-V

A few recent developments have demonstrated that deep-learning-based solutions can outperform traditional algorithms for automated pavement crack detection. In this paper, an efficient deep network called CrackNet-V is proposed for automated pixel-level crack detection on 3D asphalt pavement images. Compared with the original CrackNet, CrackNet-V has a deeper architecture but fewer parameters, resulting in improved accuracy and computation efficiency. Inspired by CrackNet, CrackNet-V uses invariant spatial size through all layers such that supervised learning can be conducted at pixel level. Following the VGG network, CrackNet-V uses $3\times 3$ size of filters for the first six convolutional layers and stacks several $3\times 3$ convolutional layers together for deep abstraction, resulting in reduced number of parameters and efficient feature extraction. CrackNet-V has 64113 parameters and consists of ten layers, including one pre-process layer, eight convolutional layers, and one output layer. A new activation function leaky rectified tanh is proposed in this paper for higher accuracy in detecting shallow cracks. The training of CrackNet-V was completed after 3000 iterations, which took only one day on a GeForce GTX 1080Ti device. According to the experimental results on 500 testing images, CrackNet-V achieves a high performance with a Precision of 84.31%, Recall of 90.12%, and an F-1 score of 87.12%. It is shown that CrackNet-V yields better overall performance particularly in detecting fine cracks compared with CrackNet. The efficiency of CrackNet-V further reveals the advantages of deep learning techniques for automated pixel-level pavement crack detection.
Investigating the Performance of Metal-Assisted Guided Mode Resonance Based Structures for Biosensing Applications

The sensing abilities of a metal-assisted guided mode resonance (MAGMR)-based structure are compared with that of a conventional guided mode resonance (GMR)-type structure operating at the same resonance wavelength. By studying the electric field intensities at resonance, it has been found that the MAGMR sensor offers a superior and more uniform sensitivity over the entire sensor surface as compared to the GMR sensors, where the sensing takes place primarily at the trenches between the grating elements. The MAGMR sensor also shows an asymmetric field profile with 44.96% of the total field extending into the sensing region at resonance in comparison with that value of 25.62% for the GMR sensor. The bulk and surface sensitivity values have also been evaluated for a range of refractive indices and analyte thicknesses, and it has been observed that the MAGMR sensor offers superior sensitivity values over the GMR sensor for all the considered cases. The limit of detection has then been calculated for both the structures, where the MAGMR structure shows a 9-fold improvement in comparison with the GMR structure for an identical readout scheme.
Lagrange equations of nonholonomic systems with fractional derivatives

This paper obtains Lagrange equations of nonholonomic systems with fractional derivatives. First, the exchanging relationships between the isochronous variation and the fractional derivatives are derived. Secondly, based on these exchanging relationships, the Hamilton's principle is presented for non-conservative systems with fractional derivatives. Thirdly, Lagrange equations of the systems are obtained. Furthermore, the d'Alembert-Lagrange principle with fractional derivatives is presented, and the Lagrange equations of nonholonomic systems with fractional derivatives are studied. An example is designed to illustrate these results.
Sequential matching problem

Kurzfassung in englisch We present sequential matching problem (SMP) as the problem of finding maximal matchings in a sequence of bipartite graphs, with a strategy of making maximum number of common edges in two consecutive matchings. One application of SMP is the problem of assigning workers to jobs in different time shifts with a goal of minimizing total number of unnecessary switches between jobs. We analyze various algorithmic techniques for this NP-complete problem. We also analyze the Mixed Integer Programming (MIP)problem formulation with huge number of variables and their solution by branch and price method, a column generation scheme with branch and bound, of implicit pricing of nonbasic variables to generate new columns. We then discuss special branching rules, pricing problems, implementation issues, and computational results. Finally we analyze a simpler version of SMP with only two bipartite graphs which is still NP-complete, and an algorithm to augment the common edges in the maximum matchings.
Period search in large datasets

The number of papers on the analysis of unevenly sampled time series is scarce. The present article is an attempt to provide a fairly simple introduction to this topic. We start with the demonstration that some procedures for analysis of unevenly sampled time series, such as the power spectrum, suffer from a number of faults and traps which make them unreliable in practice. Then we consider the application of orthogonal models in statistics and testing of statistical hypotheses. Next, we demonstrate, how these classical principles of statistics can be adapted to the analysis of unevenly sampled time series. In this way we derive new, reliable methods for analysis of unevenly sampled time series. We discuss the relevant statistics, i.e. periodogram functions and their performance, and provide tools for planning efficiency of time series observations. These methods should be particularly useful for astronomers, since astronomical time series are often sampled unevenly in time.