Miracle-dz/UniFAR-FTUs huggingface dataset:
Low Dark Current and High Responsivity UV Detector Based on TiO2 Nanowire/RGO Thin Film Heterostructure

A UV detector was fabricated using glancing angle deposition (GLAD)-synthesized TiO<sub>2</sub> nanowires (NWs) over spin-coated reduced graphene oxide (RGO) thin films (TFs) on a Si substrate. The field-emission scanning electron microscopy (FE-SEM) images showed that TiO<sub>2</sub> NWs were grown with a length of ~140 nm. The fabricated TiO<sub>2</sub> NWs were amorphous in nature, as depicted by the selected area electron diffraction (SAED) pattern which was also verified by X-ray diffraction (XRD) analysis. On average, ninefold enhanced optical absorption was observed for the TiO<sub>2</sub> NW/RGO TF/Si sample compared to the bare TiO<sub>2</sub> NW/Si sample. A significantly low dark current of 2.9 nA (at +1 V) was obtained after the incorporation of the RGO TF beneath the TiO<sub>2</sub> NWs. The fabricated Au/TiO<sub>2</sub> NW/RGO TF/Si device showed high responsivity and detectivity of 75.7 A/W and <inline-formula> <tex-math notation="LaTeX">${6.86} \times {10}^{{13}}$ </tex-math></inline-formula> Jones, respectively, under 380-nm light illumination having a power density of as low as <inline-formula> <tex-math notation="LaTeX">$0.8~\mu \text{W}$ </tex-math></inline-formula>/cm<sup>2</sup>. A low noise-equivalent power (NEP) of 49 fW was also obtained from the resulting detector. The rise and fall times of the Au/TiO<sub>2</sub> NW/RGO TF/Si detector were 0.8 and 1.09 s, respectively.
The Actuator Line Model in Lattice Boltzmann Frameworks: Numerical Sensitivity and Computational Performance

The growing use of large-eddy simulations for the modelling of wind farms makes the need for efficient numerical frameworks more essential than ever. GPU-accelerated implementations of the Lattice Boltzmann Method (LBM) have shown to provide significant performance gains over classical Navier-Stokes-based computational fluid dynamics. Yet, their use in the field of wind energy remains limited to date. In this fundamental study the cumulant LBM is scrutinised for actuator line simulations of wind turbines. The numerical sensitivity of the method in a simple uniform inflow is investigated with respect to spatial and temporal resolution as well as the width of the actuator line’s regularisation kernel. Comparable accuracy and slightly better stability properties are shown in relation to a standard Navier-Stokes implementation. The results indicate the overall suitability of the cumulant LBM for wind turbine wake simulations. The potential of the LBM for future wind energy applications is clarified by means of a brief comparison of computational performance.
Two-machine hybrid flowshop scheduling with identical jobs: Solution algorithms and analysis of hybrid benefits

Abstract We study two-machine hybrid flowshop scheduling with identical jobs. Each job consists of two tasks, namely a flexible task and a fixed task. The flexible task can be processed on either machine, while the fixed task must be processed on the second machine. The fixed task can only be processed after the flexible task is finished. Due to different technological capabilities of the two machines, the flexible task has different processing times on the two machines. Our goal is to find a schedule that minimises the makespan. We consider two variants of the problem, namely no buffer and infinite buffer capacity between the two machines. We present constant-time solution algorithms for both variants. In addition, analysing the relationship between the hybrid benefits and performance difference between the two machines, we find that, for the infinite-buffer case, increasing the technological level of the second machine does not necessarily increase the hybrid benefits.
Domains of partial attraction in several dimensions

© Gauthier-Villars, 1980, tous droits réservés. L’accès aux archives de la revue « Annales de l’I. H. P., section B » (http://www.elsevier.com/locate/anihpb) implique l’accord avec les conditions générales d’utilisation (http://www.numdam.org/conditions). Toute utilisation commerciale ou impression systématique est constitutive d’une infraction pénale. Toute copie ou impression de ce fichier doit contenir la présente mention de copyright.
Fast wideband scattering analysis of large-scale finite-sized periodic arrays with planar cells using ASED basis function and interpolation technique

ABSTRACT In this paper, the accurate sub-entire-domain (ASED) basis function method is combined with the interpolation technique to efficiently analyze the wideband electromagnetic scattering from the large-scale finite-sized periodic arrays with planar cells. Comparing with the conventional method of moments (MoM), the ASED basis function method can tremendously reduce the number of unknowns. Thus, the computational complexity can be tremendously reduced. It is a single-frequency technique. The impedance matrix needs to be calculated repeatedly at each frequency. The interpolation technique can speed up the wideband simulation because the impedance matrices can be efficiently obtained using the interpolation technique. To validate the accuracy and efficiency of the proposed method, several numerical examples are carried out. Simulation results show that the results of the proposed technique agree well with those of the ASED bases. Both the CPU time and the memory cost are significantly reduced by using the proposed method.
Active Brownian Dynamics

This thesis collects the results (already published and yet to publish) obtained during my PhD on the subject of classical nonequilibrium statistical mechanics. Mainly stochastic systems are considered, with special regard to applications in soft matter physics. First, we study the dynamics of two colloidal particles embedded in a environment driven far from equilibrium. Performing a systematic coarse-graining over the environment degrees of freedom, we derive the generalised Langevin description and extended fluctuation-dissipation relation. In particular we focus on an active matter environment and we derive the generalised Langevin equation for a colloid with a mean-field linear coupling to a bath of noninteracting active particles. In order to account for typical active effects, such as clustering, we include nonlinear interactions effects in the Langevin equation in the form of effective coefficients. This is done by means of perturbation theory and Brownian dynamics simulations. We show that the so-obtain effective minimal model well reproduces actual colloid statistics observed in experiments. Then, we investigate a heat engine based on an active Brownian particle confined in a parabolic potential and immersed in a thermal bath. Given that the potential is harmonic, the average energetics of the engine is determined by the second moment of the particle position. We map the model to a passive engine in a bath with a suitable time-dependent effective temperature. The performance of both the active and the passive engine including maximum efficiency, efficiency at maximum power and maximum efficiency at a fixed power thus obeys the same formal limitations. Finally, we investigate the pressure exerted by a fluid of active particles deriving the hydrodynamic equations of motion for the fluid described by underdamped Langevin equations. The contraction into the hydrodynamic description is performed by locally averaging the particle dynamics with the non-equilibrium many-particle probability density, whose formal expression is found in the physically relevant limit of high-friction through a multiple-time-scale analysis. This approach permits to identify the conditions under which self-propulsion can be subsumed into the fluid stress tensor and thus to define systematically and unambiguously the local pressure of the active fluid.
All-Sky-ASTROGAM: a MeV Companion for Multimessenger Astrophysics

In the era of multi-messenger astronomy it is of paramount importance to have in space a gamma-ray monitor capable of detecting energetic transients in the energy range from 0.1 MeV to a few hundred MeV, with good imaging capabilities. The All-Sky-ASTROGAM mission proposal aims to place into an L2 orbit a gamma-ray instrument ($\sim$ 100 kg) dedicated to fast detection, localization, and gamma-ray spectroscopy of flaring and merging activity of compact objects in the Universe, with unprecedented sensitivity and polarimetric capability in the MeV range. The instrument is based on the ASTROGAM concept, which combines three detection systems of space-proven technology: a silicon tracker in which the cosmic gamma rays undergo Compton scattering or a pair conversion, a scintillation calorimeter to absorb and measure the energy of the secondary particles, and an anticoincidence system to veto the prompt reaction background induced by charged particles. The gamma-ray imager and the platform will be connected through a boom and will have almost no occultation, making possible a continuous monitoring of every single gamma-ray source in the sky during the entire mission lifetime.
Thermodynamic properties, electronic and crystallographic structure, and magnetic response of the Sr2HoNbO6 material

En el presente trabajo se utilizó el código Wien2k, en el marco de la teoría del funcional de la densidad de Kohn-Sham, aplicando el método de ondas planas aumentadas y linealizadas (full-potential linearized augmented plane wave, FP- LAPW) y adoptando la aproximación de gradiente generalizado (GGA) de Perdew, Burke y Ernzerhof para la energía de intercambio y correlación, así como la aproximación de densidad local (local density approximation, LDA) para el cálculo de la densidad de estados y la estructura de bandas de la perovskita doble Sr2HoNbO6. Para los cálculos se consideró el grupo Fmm (#225), experimentalmente obtenido a partir de mediciones de difracción de rayos X y del método de refinamiento de Rietveld. El parámetro de red experimental fue de 8.018 Å, el cual concuerda en un 99,2 % con las predicciones teóricas efectuadas a partir de la minimización de la energía mediante la ecuación de estado de Murnaghan. A partir de mediciones de susceptibilidad magnética en función de la temperatura y del ajuste con la ley de Curie, se obtuvo el valor del momento magnético efectivo 10,01 μB. Este valor es muy cercano del esperado teóricamente a partir de las reglas de Hund (10,60 μB). La brecha de energía determinada entre las bandas de valencia y de conducción fue de 3,3 eV, lo que revela el carácter aislante de la perovskita compleja Sr2HoNbO6 para la configuración de espín hacia arriba, en tanto que se observó el carácter semiconductor para la polarización de espín hacia abajo, con una brecha de energía de 0,77 eV. Las propiedades termodinámicas se calcularon a partir de la ecuación de estado usando el modelo cuasi-armónico de Debye. Un comportamiento del calor específico, con CV≈CP, se encontró a temperaturas inferiores a T = 500 K, con valores del límite de Dulong-Petit que doblaban los que se han reportado para materiales del tipo de la perovskita. © 2018. Acad. Colomb. Cienc. Ex. Fis. Nat.
Deep Learning Architecture for Estimating Hourly Ground-Level PM2.5 Using Satellite Remote Sensing

The prediction of PM<sub>2.5</sub> concentration is a canonical predictive challenge due to the distribution of <inline-formula> <tex-math notation="LaTeX">$PM_{2.5}$ </tex-math></inline-formula> appears serious spatiotemporal variability at multiple scales. Currently, using satellite-based remote sensing data to estimate ground-level PM<sub>2.5</sub> is a promising method for providing spatiotemporal continuous information of PM<sub>2.5</sub>. In this letter, we proposed a deep neural network (DNN)-based PM<sub>2.5</sub> prediction model to capture the spatiotemporal variability of ground-level PM<sub>2.5</sub> using the remote sensing aerosol optical depth (AOD) data from the Himawari-8 satellite along with the conventional meteorological observation variables (denoted as PM25-DNN). The PM25-DNN model was trained and tested using the data from Beijing–Tianjin–Hebei region of China in 2017, and we compared the prediction performance between the PM25-DNN and the current state-of-the-art methods in this field. The results show that the PM25-DNN outperforms the other models with the cross-validated coefficient of determination (<inline-formula> <tex-math notation="LaTeX">$\text{R}^{2}$ </tex-math></inline-formula>), root-mean-square error (RMSE), mean prediction error (MPE), and relative prediction error (RPE) were 0.84, <inline-formula> <tex-math notation="LaTeX">$19.9~\mu \text{g}/\text{m}^{3}$ </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">$11.89~\mu \text{g}/\text{m}^{3}$ </tex-math></inline-formula>, and 41.21%, respectively. Then, the trained PM25-DNN model was applied to estimate the hourly gridded PM<sub>2.5</sub> with 1-km spatial resolution. Our results indicate that the DNN architecture can capture the essential spatiotemporal distribution associated with PM<sub>2.5</sub> only using AOD data and conventional meteorological observational variables without more handcrafted features. The proposed PM25-DNN model can greatly improve the accuracy of PM<sub>2.5</sub> estimation, and it provides a new perspective for PM<sub>2.5</sub> monitoring using end-to-end deep learning method.
Multilevel and Multiscale Deep Neural Network for Retinal Blood Vessel Segmentation

Retinal blood vessel segmentation influences a lot of blood vessel-related disorders such as diabetic retinopathy, hypertension, cardiovascular and cerebrovascular disorders, etc. It is found that vessel segmentation using a convolutional neural network (CNN) showed increased accuracy in feature extraction and vessel segmentation compared to the classical segmentation algorithms. CNN does not need any artificial handcrafted features to train the network. In the proposed deep neural network (DNN), a better pre-processing technique and multilevel/multiscale deep supervision (DS) layers are being incorporated for proper segmentation of retinal blood vessels. From the first four layers of the VGG-16 model, multilevel/multiscale deep supervision layers are formed by convolving vessel-specific Gaussian convolutions with two different scale initializations. These layers output the activation maps that are capable to learn vessel-specific features at multiple scales, levels, and depth. Furthermore, the receptive field of these maps is increased to obtain the symmetric feature maps that provide the refined blood vessel probability map. This map is completely free from the optic disc, boundaries, and non-vessel background. The segmented results are tested on Digital Retinal Images for Vessel Extraction (DRIVE), STructured Analysis of the Retina (STARE), High-Resolution Fundus (HRF), and real-world retinal datasets to evaluate its performance. This proposed model achieves better sensitivity values of 0.8282, 0.8979 and 0.8655 in DRIVE, STARE and HRF datasets with acceptable specificity and accuracy performance metrics.
Preliminary Solutions for Autonomous Mobile Robot Docking Subject to Uniform Braking Safety Constraints

This paper considers the synthesis of time optimal paths for a mobile robot docking at targets located on the boundary of a polygonal obstacle in IR. The robot must avoid the obstacle as well as satisfy velocity dependent braking safety constraints during the docking process. The classical Brachistochrone problem studies the time optimal path of a particle moving in an obstacle free environment subject to a constant force field. By encoding the braking safety constraint as a force field surrounding the obstacle, the paper generalizes the Brachistochrone problem into synthesis of time optimal paths for a mobile robot attempting to dock against an obstacle boundary. To solve the time optimal docking problem, the safe travel time functional, a path dependent function, is formulated. Convexity properties of this functional allow computation of the time optimal docking path as a convex optimization problem in O(n log(1/ε)) time, where n is the number of obstacle vertices and ε is the desired solution accuracy.
The status and performance of Cosmic Ray Air Fluorescence Fresnel lens Telescope (CRAFFT) for the next generation UHECR observatory

The next generation ultra-high energy cosmic ray (UHECR) observatory should be expanded due to the very small flux. In order to realize a huge UHECR observatory, cost reduction of detectors is one of the useful strategy. Then we are developing a Cosmic Ray Air Fluorescence Fresnel lens Telescope (CRAFFT) which is a very simple structure fluorescence detector. CRAFFT detector consists of mainly a $1.4 {\rm m^2}$ Fresnel lens, an UV transmitting filter, an 8 inch photomultiplier tube, an FADC board, and power supply system. We tested CRAFFT detector performance at Telescope Array (TA) site, and succeeded to detect UHECR air showers synchronized with TA Fluorescence Detectors. CRAFFT detector will be deployed as a huge ground array with ∼ 20 km spacing without the enough infrastructure such as in desert. Therefore, CRAFFT detectors can stand alone. We are developing automatic observation and protecting detector system. Additionally, we are studying our detector performance by detector simulation to estimate trigger efficiency, establish a reconstruction procedure, and optimize our detector configuration. In this presentation, we will report the result of the test operation of automatic observation and protecting detector system for CRAFFT detector, and the detector performance and optimization.
Avaliação do impacto dos tipos de equipamentos de medição no desempenho da detecção de defeitos em sistemas de distribuição utilizando redes neurais

Neste trabalho e desenvolvida uma metodologia para a deteccao de defeitos monofasicos com impedância na media tensao de sistemas de distribuicao e avalia-se o impacto da utilizacao de diferentes tipos de equipamentos no desempenho da deteccao do defeito. A escolha da deteccao de defeitos monofasicos e baseada no fato de que estas sao a grande maioria nos sistemas de distribuicao. A metodologia proposta consegue identificar defeitos monofasicos com resistencia de arco variando entre 0 a 20 ohms, porem, a metodologia nao teve como objetivo a deteccao de defeitos de alta impedância. Alem disto, a metodologia proposta e capaz de detectar corretamente os defeitos considerando a variacao do carregamento do sistema. O indice de acerto da deteccao alcancado pela metodologia proposta foi maior do que 95% em todos os casos simulados. Sendo que, neste trabalho, para realizar a deteccao de defeitos em sistemas de distribuicao foram utilizadas redes neurais artificiais, onde as entradas sao grandezas eletricas de tensao e corrente, podendo ser medicoes fasoriais e/ou nao-fasoriais. Esta variacao serviu para analisar o desempenho na deteccao do defeito do emprego de diferentes tipos de equipamentos de medicao.
Active Cues Collection and Integration for Building Extraction With High-Resolution Color Remote Sensing Imagery

Building extraction from high-resolution color remote sensing imagery (HRCRSI) is important in city planning, building reconstruction, and other applications. However, the performance of the state-of-the-art methods is often passively dependent on the accuracy and reliability of the initial edges/regions acquired by general edge/region extraction methods. But the performance of these general methods is always sensitive to unavoidable noise and interferences, especially for the HRCRSI imagery. Furthermore, structural information of the target (e.g., buildings herein) is not fully utilized in these general methods, which is undoubtedly a useful clue to reducing the effects of noise and interference. Therefore, undesired results are inevitable for building extraction methods conducted with a passive or semiactive manner. In this paper, in order to alleviate this problem to a certain extent, we carried out the building extraction task in a completely active manner: 1) under the guidance of the visual perception theory, cues of building edges and regions are actively collected by considering building priors related to main direction and color; and 2) based on knowledge about building shape widely accepted in the literature, cues of the obtained building edges and regions are actively integrated for final building extraction. Experimental results on three benchmark datasets, including aerial and high-resolution optical satellite images, illustrate that the proposed active method can achieve the expected building extraction results.
Robust FOPID controller design for fractional‐order delay systems using positive stability region analysis

In this paper, a robust fractional‐order PID (FOPID) controller design method for fractional‐order delay systems is proposed based on positive stability region (PSR) analysis. Firstly, the PSR is presented to improve the existing stability region (SR) in D‐decomposition method. Then, the optimal fractional orders λ and μ of FOPID controller are achieved at the biggest three‐dimensional PSR, which means the best robustness. Given the optimal λ and μ, the other FOPID controller parameters kp, ki, kd can be solved under the control specifications, including gain crossover frequency, phase margin, and an extended flat phase constraint. In addition, the steps of the proposed robust FOPID controller design process are listed at length, and an example is given to illustrate the corresponding steps. At last, the control performances of the obtained robust FOPID controller are compared with some other controllers (PID and FOPI). The simulation results illustrate the superior robustness as well as the transient performance of the proposed control algorithm.
Dynamics of viscoelastic pipe flow in the maximum drag reduction limit.

Polymer additives can substantially reduce the drag of turbulent flows and the upper limit, the so called "maximum drag reduction" (MDR) asymptote is universal, i.e. independent of the type of polymer and solvent used. Until recently, the consensus was that, in this limit, flows are in a marginal state where only a minimal level of turbulence activity persists. Observations in direct numerical simulations using minimal sized channels appeared to support this view and reported long "hibernation" periods where turbulence is marginalized. In simulations of pipe flow we find that, indeed, with increasing Weissenberg number (Wi), turbulence expresses long periods of hibernation if the domain size is small. However, with increasing pipe length, the temporal hibernation continuously alters to spatio-temporal intermittency and here the flow consists of turbulent puffs surrounded by laminar flow. Moreover, upon an increase in Wi, the flow fully relaminarises, in agreement with recent experiments. At even larger Wi, a different instability is encountered causing a drag increase towards MDR. Our findings hence link earlier minimal flow unit simulations with recent experiments and confirm that the addition of polymers initially suppresses Newtonian turbulence and leads to a reverse transition. The MDR state on the other hand results from a separate instability and the underlying dynamics corresponds to the recently proposed state of elasto-inertial-turbulence (EIT).