bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimal design of proportional‐resonant controller and its harmonic compensators for grid‐integrated renewable energy sources based three‐phase voltage source inverters
Authors: Ebrahim Mohamed A. , Aziz Beshoy Abdou , Nashed Maged N. F. , Osman Fawzy A. 
Published: December 2020

AbstractThis paper proposes new analytical and optimal design procedures of the proportional‐resonant (PR) controller and its harmonic compensators (HCs) for three‐phase grid‐connected voltage source inverters (VSIs) powered by renewable energy resources. The modeling and analysis based on stationary reference frame are performed for VSIs collaborated with an L‐type filter. The theoretical verification and simulation validation of the proposed design guidelines are done to approve its effectiveness and robustness. Particle swarm, grey wolf and Harris hawks' optimization techniques are applied and compared for a proper selection of the parameters of the proposed PR controller and its HCs. To accomplish this study, multi‐objective error functions are employed and compared to minimize the total harmonic distortion of the grid output current. The proposed PR controller and its HCs are tested, using MATLAB/Simulink, along with the allowable changes of inverter output active and reactive powers, and also under the grid voltage distortion. Moreover, their performance is evaluated according to IEEE and IEC harmonics standards, and compared with the conventional PI controller based on reference frame. Furthermore, the experimental validation for the proposed controllers is done based on the hardware‐in‐the‐loop real‐time simulator using C2000TM‐microcontroller‐LaunchPadXL‐TMS320F28377S kit.
A probabilistic collaborative dictionary learning‐based approach for face recognition
Authors: Lv Shilin , Liang Jiuzhen , Di Lan , Yunfei Xia , Hou ZhenJie 
Published: December 2020

AbstractAlthough Sparse Representation based Classifier (SRC), a non‐parametric model, can obtain an interesting result for pattern recognition , a reasonable interpretation has been lacked for its classification mechanism. What is more, the training samples are used as off‐the‐shelf dictionary directly in SRC, which can make the feature hidden in the training samples hard be extracted. At the same time, the complexity of the algorithm is increased because of too many atoms of the dictionary. The authors first explains in detail the classification mechanism of SRC from the view of probabilistic collaborative subspace and offer the process to improve the stability of the algorithm using the joint probability in the case of the multi‐subspace. Then, the authors introduce the dictionary learning (DL) and Fisher criterion into the model to further enhance the discrimination of the coding coefficient. In order to ensure the convexity of the discrimination term and further enhance the discrimination, the authors add the L21‐norm term into the Fisher discrimination term and offer the proof for its convexity. Finally, the experimental result on a series of benchmark databases, such as AR, Extended Yale B, LFW3D‐hassner, LFW3D‐sdm and LFW3D‐Dlib, show that PCDDL outperforms existing classical classification models.
Paralleled attention modules and adaptive focal loss for Siamese visual tracking
Authors: Zhao Yuyao , Jiang Min , Kong Jun , Li Sha 
Published: December 2020

AbstractRecently, Siamese‐based trackers have drawn amounts of attention in visual tracking field because of their excellent performance on different tracking benchmarks. However, most Siamese‐based trackers encounter difficulties under circumstances such as similar objects interference and background clutters. Besides, there exists an extreme foreground–background data imbalance that weakens the performance during training but few loss functions pay attention to it. The authors intend to address the issues mentioned above by introducing a module named paralleled spatial and channel attention (PSCA) and adaptive focal loss (AFL). Firstly, paralleled spatial and channel attention is proposed to enhance the extracted features and eliminate the noise information from both spatial and channel aspects. Secondly, adaptive focal loss is proposed as the loss function to make the model focus on hard samples that contribute more to training process. Finally, paralleled spatial and channel attention and modified ResNet are combined for extracting more powerful features. Experimental results show that the authors' method achieves outstanding performance in multiple benchmarks while keeping a beyond‐real‐time frame rate.
Inertia property determination by spectrum analysis of damped oscillation detection signal
Authors: Zhang Lieshan , Wang Meibao , Liu Pu 
Published: December 2020

AbstractOscillation method is the most effective approach to determine the inertia properties of rigid bodies. This paper proposes a new signal processing method to determine the moment of inertia (MoI) accurately in the presence of high frictional damping when using a torsion pendulum setup. A mathematical model of damped oscillation is established, and the analytic form of Fourier transformation of the damped torsional oscillation is derived. A formula for calculating the MoI in relation to the dominant frequency and damping ratio is also derived. An algorithm regarding periodic extension and normalization of torsional oscillation signal is proposed to calculate the dominant frequency and damping ratio of torsional oscillation in the frequency domain. The feasibility and accuracy of this algorithm are verified by both numerical simulations and measurement experiments. The experimental results show that the proposed method has good measurement repeatability, and the relative error of measurement is within 0.80%.
Kinematics and star formation toward W33: a central hub as a hub–filament system
Authors: Liu Xiao-Lan , Xu Jin-Long , Wang Jun-Jie , Yu Nai-Ping , Zhang Chuan-Peng , Li Nan , Zhang Guo-Yin 
Published: December 2020

Aims. We investigate the gas kinematics and physical properties toward the W33 complex and its surrounding filaments. We study clump formation and star formation in a hub–filament system.
Methods. We performed a large-scale mapping observation toward the W33 complex and its surroundings, covering an area of 1.3° × 1.0°, in 12CO (1–0), 13CO (1–0), and C18O (1–0) lines from the Purple Mountain Observatory (PMO). Infrared archival data were obtained from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE), the Multi-band Imaging Photometer Survey of the Galaxy (MIPSGAL), and the Herschel Infrared Galactic Plane Survey (Hi-GAL). We distinguished the dense clumps from the ATLASGAL survey. We used the GLIMPSE I catalogue to extract young stellar objects.
Results. We found a new hub–filament system ranging from 30 to 38.5 km s−1 located at the W33 complex. Three supercritical filaments are directly converging into the central hub W33. Velocity gradients are detected along the filaments and the accretion rates are in order of 10−3 M⊙ yr−1. The central hub W33 has a total mass of ~1.8 × 105 M⊙, accounting for ~60% of the mass of the hub–filament system. This indicates that the central hub is the mass reservoir of the hub-filament system. Furthermore, 49 ATLASGAL clumps are associated with the hub–filament system. We find 57% of the clumps to be situated in the central hub W33 and clustered at the intersections between the filaments and the W33 complex. Moreover, the distribution of Class I young stellar objects forms a structure resembling the hub–filament system and peaks at where the clumps group; it seems to suggest that the mechanisms of clump formation and star formation in this region are correlated.
Conclusions. Gas flows along the filaments are likely to feed the materials into the intersections and lead to the clustering and formation of the clumps in the hub–filament system W33. The star formation in the intersections between the filaments and the W33 complex might be triggered by the motion of gas converging into the intersections.
A “no-drift” runaway pile-up of pebbles in protoplanetary disks in which midplane turbulence increases with radius
Authors: Hyodo Ryuki , Ida Shigeru , Guillot Tristan 
Published: December 2020

Context. A notable challenge of planet formation is to find a path to directly form planetesimals from small particles.
Aims. We aim to understand how drifting pebbles pile up in a protoplanetary disk with a nonuniform turbulence structure.
Methods. We consider a disk structure in which the midplane turbulence viscosity increases with the radius in protoplanetary disks, such as in the outer region of a dead zone. We perform 1D diffusion-advection simulations of pebbles that include back-reaction (the inertia) to the radial drift and the vertical and radial diffusions of pebbles for a given pebble-to-gas mass flux.
Results. We report a new mechanism, the “no-drift” runaway pile-up, that leads to a runaway accumulation of pebbles in disks, thus favoring the formation of planetesimals by streaming and/or gravitational instabilities. This occurs when pebbles drifting in from the outer disk and entering a dead zone experience a decrease in vertical turbulence. The scale height of the pebble subdisk then decreases, and, for small enough values of the turbulence in the dead zone and high values of the pebble-to-gas flux ratio, the back-reaction of pebbles on gas leads to a significant decrease in their drift velocity and thus their progressive accumulation. This occurs when the ratio of the flux of pebbles to that of the gas is large enough that the effect dominates over any Kelvin-Helmholtz shear instability. This process is independent of the existence of a pressure bump.
Resection of a Lower Clival Meningioma via Posterolateral Approach: Two-Dimensional Operative Video
Authors: Ocak Pinar E. , Yilmazlar Selcuk 
Published: December 2020

Abstract
Objectives This study aimed to demonstrate resection of a craniovertebral junction (CVJ) meningioma via the posterolateral approach.
Design The study is designed with a two-dimensional operative video.
Setting This study is conducted at department of neurosurgery in a university hospital.
Participants A 50-year-old woman who presented with lower cranial nerve findings due to a left-sided lower clival meningioma (Fig. 1).
Main Outcome Measures Microsurgical resection of the meningioma and preservation of the neurovascular structures.
Results The patient was placed in park-bench position and a left-sided retrosigmoid suboccipital craniotomy, followed by C1 hemilaminectomy and unroofing the lip of the foramen magnum, was performed. The dural incision extended from the suboccipital region down to the posterior arch of C2 (Fig. 2). The arachnoid overlying the tumor was incised, revealing the course of the cranial nerve (CN) XI on the dorsolateral aspect of the tumor. The left vertebral artery (VA) was encased by the tumor which was originating from the dura below the jugular foramen. The mass was resected in a piecemeal fashion eventually. At the end of the procedure, all relevant cranial nerves and adjacent vascular structures were intact. Postoperative magnetic resonance imaging (MRI) confirmed total resection and the patient was discharged home on postoperative day 3 safely.
Conclusions Microsurgical resection of the lesions of the CVJ are challenging as this transition zone between the cranium and upper cervical spine has a complex anatomy. Since adequate exposure of the extradural and intradural segments of the VA can be obtained by the posterolateral approach, this approach can be preferred in cases with tumors anterior to the VA or when the artery is encased by the tumor.The link to the video can be found at: https://youtu.be/d3u5Qrc-zlM.
A method of incorporating rate constants as kinetic constraints in molecular dynamics simulations
Authors: Brotzakis Z. Faidon , Vendruscolo Michele , Bolhuis Peter G. 
Published: December 2020

Significance
Molecular dynamics simulations are often combined with experimental data with the aim to improve structural models. Here, we introduce a method of imposing known rate constants as constraints in such simulations, based on a combination of the maximum-entropy and maximum-caliber principles. The method corrects an initial path ensemble by reweighting it in order to match the calculated and experimental interconversion rates of a molecular transition of interest, yielding improved structure, kinetics, and thermodynamics, as well as mechanistic insights that may not be readily evident directly from the experiments.
Femtometer atomic displacement, the root cause for multiferroic behavior of CuO unearthed through polarized Raman spectroscopy
Authors: De Binoy Krishna , Dwij Vivek , Misawa R , Kimura T , Sathe V G 
Published: December 2020

Abstract
Recently, CuO has been proposed as a potential multiferroic material with high transition temperature. Competing models based on spin current and ionic displacements are invoked to explain ferroelectricity in CuO. The theoretical model based on ionic displacement predicted very small displacement (∼10−5 Å) along the b axis. Experimentally detecting displacements of such a small amplitude in a particular direction is extremely challenging. Through our detailed angle resolved polarized Raman spectroscopy study on single crystal of CuO, we have validated the theoretical study and provided direct evidence of displacement along the b axis. Our study provides important contribution in the high temperature multiferroic compounds and showed for the first time, the use of the polarized Raman scattering in detecting ionic displacements at the femtometer scale.
Mid-IR stimulated emission in Hg(Cd)Te/CdHgTe quantum well structures up to 200 K due to suppressed Auger recombination
Authors: Utochkin V V , Kudryavtsev K E , Fadeev M A , Razova A A , Bykov D S , Ya Aleshkin V , Dubinov A A , Mikhailov N N , Dvoretsky S A , Rumyantsev V V , Gavrilenko V I , Morozov S V 
Published: December 2020

Abstract
We study the temperature stability of stimulated emission (SE) in HgCdTe/CdHgTe quantum well (QW) heterostructures emitting in the mid-infrared range at wavelengths 7–13 μm. For a series of samples with different band gap energies, maximum operating temperatures at which SE could be achieved are shown to follow closely the characteristic Auger threshold energies derived from the band spectra of the respective QWs. We demonstrate that realization of binary HgTe QWs should provide at least twofold increase in Auger threshold energy compared to the QWs studied (10% Cd content HgCdTe). Thus, one can expect further suppression of non-radiative Auger processes and corresponding increase in operating temperature, the effect being stronger for narrow band gap QWs.
Switchable dissipative soliton resonance and noise like pulses regimes in a mode-locked double-clad thulium doped fiber laser
Authors: Durán-Sánchez M , Posada-Ramírez B , Álvarez-Tamayo R I , Bello-Jiménez M , García-Flores Y A , Armas-Rivera I , Montiel-Piña E , Kuzin E A , Ibarra-Escamilla B 
Published: December 2020

Abstract
We report an experimental study of switchable rectangular pulses generation in a passively mode-locked double-clad thulium-doped fiber laser operating in the anomalous dispersion regime. A fiber loop mirror and a polarization imbalanced nonlinear optical loop mirror (NOLM) forms the linear cavity. The loop in the NOLM includes a quarter-wave retarder, which allows switching between two regimes of rectangular pulse generation. The laser generates rectangular noise-like pulses (NLPs) or dissipative soliton resonance (DSR) pulses with 1.18 MHz repetition rate at ∼1990 nm. At the maximum pump power of 10 W, rectangular pulses with energy of up to 540 nJ in DSR operation and 482 nJ in NLP operation were obtained with output average power of 640 mW and 571 mW, respectively.
Experimental observation of the localized coupling between geodesic acoustic mode and magnetic islands in tokamak plasmas
Authors: Xu Ming , Kong D.F. , Liu A.D. , Liang Y.F. , Cai H.S. , Qiu Z.Y. , Chen W. , Shi T.H. , Duan Y.M. , Xiang H.M. , Wang Y.M. , Zhang T. , Zhang S.B. , Gao X. , Feng X. , Zhou C. , Zhuang G. , Hu L.Q. , Xu G.S. , Gong X.Z. , Zhang X.D. , Wan B.N. , the EAST Team  
Published: December 2020

Abstract
The localized coupling among geodesic acoustic mode (GAM), tearing modes (TMs) and twin counter-propagating beta-induced Alfvén eigenmodes (BAEs) waves has been investigated in the experimental advanced superconducting tokamak. Before the appearance of TMs, typical continuous GAM is observed through the multi-channel Doppler backscattering (DBS) diagnostic. The twin BAEs can be excited after the burst of magnetic islands, which are localized to the q = 4 rational surface that is confirmed by the measurement of DBS array, where the GAM and twin BAEs are observed synchronically at R ≈ 2.23 m (normalized radius ρ ≈ 0.8). One reasonable excitation mechanism is proposed that the twin BAEs can be excited by the nonlinear interaction between GAM and magnetic islands. As the width of magnetic islands increases, the electromagnetic twin BAEs increase synchronically with the decreasing of electrostatic GAM, strongly suggesting that the electromagnetic components are pumped from three-wave interaction between electrostatic GAM and magnetic islands.
Influence of listening to music on emotional state of programmers: Preliminary study
Authors: Tarasau Herman , Thapaliya Ananga 
Published: December 2020

Abstract
The performance of programmer is crucial in software developing process. The performance can be influenced by the number of external factors, such as noise, illumination etc. These work uses Electroencephalography to understand the influence of music on programmers mental state. Several(n=8) programmers were given the task according to their proficiency. They were asked to solve different tasks with music and without. The arousal-valence coefficients were calculated in order to understand emotional state of programmers. As results, the mean Arousal and Valence levels are lower and higher respectively, while listening to music. Further researches may use the proposed methods as baseline. Also, we strongly advice to increase the number of samples and asses other factors that could potentially influence the emotional state.
Integrated Navigation System of Single-Axle Wheeled Robot With Two Degrees of Freedom Rotating Platform
Authors: Aleshin B.S. , Kuris E.D. , Lelkov K.S. , Miheev V.V. , Chernomorsky A.I. 
Published: December 2020

Abstract
A complex navigation system for a uniaxial wheeled robot with a two degrees of freedom rotating platform, which is a carrier of environmental monitoring equipment, is proposed. The navigation system includes an odometric subsystem, a block of inertial sensors, laser altimeters, and a receiver of the global navigation satellite system. Integration is carried out based on the use of the Kalman filter, taking into account the possibility of deformation of the wheels and their slippage when the robot moves relative to the non-horizontal underlying surface. The results of semi-natural modeling confirmed the effectiveness of the decisions made.
Development and modeling of the weighting algorithm of the passenger vehicle transportation quality
Authors: Aleksandrovich Zhuravlev Aleksandr , Petrovna Aksyonova Olga , Evgenevna Ziomkovskaia Polina 
Published: December 2020

Abstract
At the moment, the role of passenger vehicles (PV) in human life is quite large. People use PV almost every day. Recently, however, the roads are becoming more overloaded due to the increase in the number of vehicles. Consequently, the likelihood increases of less quality transportation. And the indicator of the quality of transportation is key in its assessment. One way to solve this problem is to develop an application that allows users to provide better information on how to get to their destination. However, for such an application to work, it is necessary to develop an algorithm by which it will work. This article proposes a weighting algorithm for assessing the quality of transportation of passenger vehicles. This algorithm works according to the following principle: the destination enters; the user assigns weight values to the characteristics of transportation (for example, convenience, safety, etc.); there is a comparative characteristic of vehicles going to the destination for each of the criteria (places are assigned for each of the criteria); at the end, the rating of each vehicle is compiled on the basis of multiplying the weight values of the vehicle seat by the criterion and the weight coefficient of the transportation criterion and further summing up the resulting terms.
Preliminary result on how to enhance online education during the COVID-19 pandemic
Authors: Fawaz Imam Muwaffaq Mohammad 
Published: December 2020

Abstract
In 2020 and because of COVID-19 pandemic, all institution transformed into online education is well established that there was no face to face teaching anymore and some institute and teachers were not ready to deal with, moreover students didn’t adapt to start the learning process online, This study shows aims to determine the best methods and technique we can use to give the best online education experience for both students and teachers in all institution wither if it’s academic, business or an individual. To test the hypothesis that we can enhance online education for all students an online survey was distributed to 115 students who study bachelor computer science and were taking online classes through Zoom and Youtube, the result showed that students prefer to digital pen and vLogs over slides, they care about video’s sound quality and prefer to watch 10 - 15 min video duration also they welcomed the Youtube chapters new technique to divided the long video into sections plus they prefer the audience engaging, energetic teaching style. The result showed that students are adapting to online learning and some of our technique were well received and some had no effect, On this basis, the concept of enhancing online education through new tools and practising new methods and trying them can taking into account when creating an online class in any educational institution.
Developing a Mobile Application Using Open Source Parking Management System on Etherium Smart Contracts
Authors: Imbugwa Gerald , Mazzara Manuel , Distefano Salvatore 
Published: December 2020

Abstract
In this paper, we envision to illustrate the process to be used in developing a mobile application on the smart contract. We start by looking at what other researchers have accomplished and how we can improve on what already exists. The paper highlights the requirement gathering process, the methodology for data collection to streamline and validate the requirement, the architecture and implementation phase by analyzing the technological stack to achieve the business goal.
Dynamical systems analysis using many-task interactive cloud computing
Authors: Popov Stefan N. , Vostokin Sergei V. , Doroshin Anton V. 
Published: December 2020

Abstract
The article states an approach for developing a distributed application architecture for dynamic systems analysis in a hybrid cloud. The problem that was posed as an example is based on the calculation of the Lyapunov characteristic exponents for trajectories of dynamical systems in phase space. Parallelization of the computational process is achieved by supplying the list of running tasks for computing Lyapunov characteristic exponents, depending on the result of finished tasks during calculations. We have implemented a distributed application to make this experiment automated. The architecture of application elements is established on the principles of the enterprise desktop grid and cloud systems. A vital detail of the application architecture is the deployment process based on a cloud hybrid computing environment using the Jupyter server running on the DigitalOcean cloud platform and the Everest cloud platform simultaneously with the Maple package.