bluuebunny/crossref_metadata_2025_split huggingface dataset:
Semi-supervised EEG emotion recognition model based on enhanced graph fusion and GCN
Authors: Li Guangqiang , Chen Ning , Jin Jing 
Published: April 2022

Abstract

Objective. To take full advantage of both labeled data and unlabeled ones, the Graph Convolutional Network (GCN) was introduced in electroencephalography (EEG) based emotion recognition to achieve feature propagation. However, a single feature cannot represent the emotional state entirely and precisely due to the instability of the EEG signal and the complexity of the emotional state. In addition, the noise existing in the graph may affect the performance greatly. To solve these problems, it was necessary to introduce feature/similarity fusion and noise reduction strategies. Approach. A semi-supervised EEG emotion recognition model combining graph fusion, network enhancement, and feature fusion was proposed. Firstly, different features were extracted from EEG and then compacted by Principal Component Analysis (PCA), respectively. Secondly, a Sample-by-sample Similarity Matrix (SSM) was constructed based on each feature, and similarity network fusion (SNF) was adopted to fuse the graphs corresponding to different SSMs to take advantage of their complementarity. Then, Network Enhancement (NE) was performed on the fused graph to reduce the noise in it. Finally, GCN was performed on the concatenated features and the enhanced fused graph to achieve feature propagation. Main results. Experimental results demonstrated that: (a) When 5.30

%

of SEED and 7.20

%

of SEED-IV samples were chosen as the labeled samples, respectively, the minimum classification accuracy improvement achieved by the proposed scheme over state-of-the-art schemes were 1.52

%

on SEED and 13.14

%

on SEED-IV, respectively. (b) When 8.00

%

of SEED and 9.60

%

of SEED-IV samples were chosen as the labeled samples, respectively, the minimum training time reduction achieved by the proposed scheme over state-of-the-art schemes were 46.75 s and 22.55 s, respectively. (c) Graph fusion, network enhancement, and feature fusion all contributed to the performance enhancement. (d) The key hyperparameters that affect the performance were relatively few and easy to set to obtain outstanding performance. Significance. This paper demonstrated that the combination of graph fusion, network enhancement, and feature fusion help to enhance GCN-based EEG emotion recognition.
Nonlinear response of human trunk musculature explains neuromuscular stabilization mechanisms in sitting posture
Authors: Noamani Alireza , Vette Albert H , Rouhani Hossein 
Published: April 2022

Abstract

Objective. Determining the roles of underlying mechanisms involved in stabilizing the human trunk during sitting is a fundamental challenge in human motor control. However, distinguishing their roles requires understanding their complex interrelations and describing them with physiologically meaningful neuromechanical parameters. The literature has shown that such mechanistic understanding contributes to diagnosing and improving impaired balance as well as developing assistive technologies for restoring trunk stability. This study aimed to provide a comprehensive characterization of the underlying neuromuscular stabilization mechanisms involved in human sitting. Approach. This study characterized passive and active stabilization mechanisms involved in seated stability by identifying a nonlinear neuromechanical physiologically-meaningful model in ten able-bodied individuals during perturbed sitting via an adaptive unscented Kalman filter to account for the nonlinear time-varying process and measurement noises. Main results. We observed that the passive mechanism provided instant resistance against gravitational disturbances, whereas the active mechanism provided delayed complementary phasic response against external disturbances by activating appropriate trunk muscles while showing non-isometric behavior. The model predicted the trunk sway behavior during perturbed sitting with high accuracy and correlation (average: 0.0007 (rad2) and 86.77%). This allows a better mechanistic understanding of the roles of passive and active stabilization mechanisms involved in sitting. Significance. Our characterization approach accounts for the inherently nonlinear behavior of the neuromuscular mechanisms and physiological uncertainties, while allowing for real-time tracking and correction of parameters’ variations due to external disturbances and muscle fatigue. The outcome of our research, for the first time, (a) allows a better mechanistic understanding of the roles of passive and active stabilization mechanisms involved in sitting; (b) enables objective evaluation and targeted rehabilitative interventions for impaired balance; facilitate bio-inspired designs of assistive technologies, and (c) opens new horizons in mathematical identification of neuromechanical mechanisms employed in the stable control of human body postures and motions.
Graphene oxide reinforced epoxy nanocomposites coatings for corrosion protection: a review
Authors: Harsha Voleti Sri Sai , Sharma Ambuj , Tambe Pankaj 
Published: April 2022

Abstract
Graphene oxide (GO) is a reinforcing filler material used in epoxy resin to make coatings for improving the corrosion resistance of epoxy. The synthesis methods of GO are discussed with their modification methods (covalently and non-covalently). The incorporation of GO in epoxy resin nanocomposites coatings shows the improved corrosion resistance and adhesion strength depends on the processing protocol and aspect ratio of GO. Modification of GO covalently and non-covalently and reinforced in epoxy nanocomposites coatings show the enhanced corrosion protection as compared to pure epoxy and epoxy/GO nanocomposites coatings due to improved dispersion of GO in an epoxy matrix. Inorganic nanofiller modified with GO as hybrid reinforcement in epoxy nanocomposites coatings shows improved corrosion resistance as compared to epoxy/GO nanocomposites. GO/inorganic hybrid filler reinforced in epoxy nanocomposites coatings are promising in terms of applications in the industry for long time corrosion protection.
Optimization of atomic layer deposition of Al2O3 films as possible template for graphene transfer
Authors: Blagoev B S , Delibatov D A , Mehandzhiev V B , Sveshtarov P , Terziyska P , Avramova I , Rafailov P M 
Published: April 2022

Abstract
Nanofilms of aluminium oxide Al2O3 (ALO) were grown on Si, Cu and graphene/Cu substrates by atomic layer deposition (ALD). Trimethylaluminium (TMA) and deionized (DI) water were used as precursors for the ALD process. In order to obtain the ALD temperature window for the above-mentioned precursors, ALO nanofilms were deposited on Si substrates at temperatures ranging from 50 °C to 300 °C. Based on ellipsometry measurements of the films thickness, the growth rate of ALO films obtained was between 1.15 Å/cycle and 1.25 Å/cycle. Ellipsometry and XPS analyses showed that the optimal growth temperature for ALO films is between 150 °C and 200 °C. A graphene layer was grown on a Cu foil by chemical vapor deposition (CVD) and coated with an ALD ALO nanofilm. Raman spectroscopy was used to characterize the influence of ALO films deposition on the graphene layer. A Raman intensity enhancement for all graphene bands in the Al2O3/graphene/Cu sample was observed.
Improvement in the gas-sensing properties of a ZnO:Zn2TiO4 composite sensor by light irradiation
Authors: Atanasova G , Dilova T , Dikovska A , Nikov Ru , Nedyalkov N 
Published: April 2022

Abstract
In the present study, we demonstrate the application of highly porous ZnO:Zn2TiO4 nanocomposites as gas sensors. The composite sensor elements were prepared by pulsed laser deposition performed in air at atmospheric pressure. Gas detection was achieved through irradiating the sensor surface with UV light. The gas-sensing properties of the composite sensor were studied under exposure to ammonia, carbon monoxide, ethanol, and acetone. The highest response rate of the sensor element was observed in the case of exposure to carbon monoxide, with detection below 1 ppm being demonstrated. The influence was investigated of the additional light irradiation on the response and the times of response and recovery of the sensor elements. It was found that illuminating the sensor surface with blue light increased the sensor response to all tested gases, while a red-light irradiation enhanced the sensor element selectivity to carbon monoxide.
Plasmonic stop-band filter based on an MIM waveguide coupled with cavity resonators
Authors: Zegaar Imane , Hocini Abdesselam , Khedrouche Djamel , Ben salah Hocine , bahri Hocine 
Published: April 2022

Abstract
In this study, we propose and simulate in the NIR region a tunable stop-band filter based on an MIM waveguide coupled to a triangular cavity. The transmission spectra of the filter are obtained using the R-Soft CAD software based on the two-dimension (2D) finite-difference time-domain (FDTD) method, which uses perfectly matched layers (PML) to absorb the outgoing energy fields. A stop-band plasmonic filter with a large bandwidth and high bandpass transmission is achieved by adding another triangular cavity resonator. One can also control the range filtered and the shift of the central wavelength by tuning the second triangular cavity parameters. This structure has important applications in highly integrated photonic circuits.
Organic bulk heterojunction solar cells spin-coated in ambient environment on flexible and glass substrates
Authors: Gergova R , Sendova-Vassileva M , Popkirov G , Dikov Hr , Grancharov G , Terziyska P 
Published: April 2022

Abstract
Organic solar cells based on Poly (3-hexylthiophene) [6,6]-phenyl C61-butyric acid methyl ester (P3HT-PCBM) were fabricated in standard architecture by spin-coating on glass and on flexible polyethylene terephthalate (PET) substrates in ambient laboratory environment. In addition to the conventional DC characterization, impedance spectroscopy was used in order to study the capacitive behavior of the devices and obtain their electrical parameters. In combination with the electrical characterization methods, laser-beam-induced current (LBIC) measurements were used as a non-destructive method of mapping the photocurrent distribution and analyzing local device failures and macroscopic defects (shunts, dark spots, defects). The results of the study can be used to develop guidelines for the development and design of P3HT:PCBM solar cells in ambient environment.
Conversion of CO2 in a pulsed arc discharge
Authors: Vasilev V , Iordanova S , Vladkov E , Kolev St 
Published: April 2022

Abstract
We present a study of CO2 gas conversion into a mixture of CO2, CO and O2 by means of a pulsed arc discharge at atmospheric pressure. The CO2 molecule is dissociated as a result of the interaction with the highly energetic electrons and excited species produced in the plasma domain. The plasma conversion of CO2 provides a relatively simple approach to CO2 conversion without the need of special materials required by chemical reactors. In this study, the discharge operates at atmospheric pressure, which leads to a reduced efficiency compared to the low pressure operation due to the additional electron losses via elastic collisions. The operation at atmospheric pressure, however, provides simplicity, robustness and low cost of the discharge system, which makes it very attractive from an industrial point of view. Further, we use a pulsed discharge, which, in comparison to the DC discharges, provides additional possibilities for optimizing the dissociation process by controlling precisely the energy input into the plasma. This is achieved by controlling the pulse repetition rate and duty ratio in addition to the discharge current and gas flow characteristics. We present results for the CO2 dissociation rate and energy efficiency for a wide range of different discharge parameters.
Vertical and near-horizontal scanning lidar observations of aerosol loads over Sofia, Bulgaria, in the presence of Saharan dust
Authors: Peshev Z , Deleva A , Chaikovsky A , Pescherenkov V , Vulkova L , Dreischuh T 
Published: April 2022

Abstract
Intrusions of extraneous aerosols and their interactions with locally produced aerosols result in serious climatic, ecological and health effects and consequences. In this work, we analyze results of lidar observations during Saharan dust loads in the atmosphere above the city of Sofia. Two types of measurements are described, namely, vertical lidar sounding and near-surface aerosol mapping by quasi-horizontal lidar scanning. The temporal dynamics of the aerosol density vertical distribution is displayed by color-mapped time series of range-corrected lidar signals. The resulting time-averaged profiles of the backscattering coefficients at two lidar wavelengths (532 nm and 1064 nm) were retrieved and the topological parameters of the detected aerosol fields were determined. The aerosols’ microphysical characteristics and their height distribution were estimated by calculating the backscatter-related Ångström exponent. Presented and analyzed are results of vertical profiling of the total and mode volume concentration for the aerosol/dust fractions obtained by using the inversion code LIRIC-2 based on combined synergistic use of data from the CALIPSO satellite on-board lidar and sun-photometer data. The quasi-horizontal mapping of near-ground aerosols was carried out over a large urban area of the city of Sofia of about 25 km2 within a 50° angular sector in a south-western direction. The results presented in the work demonstrate the capabilities of the combined approach including lidar, radiometer, satellite measurements and theoretical modeling in conducting effective ecological monitoring of the atmospheric aerosol pollution.
Accuracy comparison of intraoral versus laboratory scanners used in the contemporary dental practice
Authors: Galeva H , Uzunov T , Sofronov Y , Todorov G 
Published: April 2022

Abstract
The aim of this in vitro study was to compare the quality of the data obtained by intraoral and by laboratory 3D scanners. An artificial jaw with an acrylic tooth prepared for a full metal ceramic crown was used as a master model of the prosthetic field. A reference model was created by scanning this field by a coordinate measuring machine (CCM). The acrylic master model was scanned by four scanners using three different methods and six digital models were obtained. They were divided in three groups - direct intraoral scanning (DIS), laboratory stone scanning (LSS) and laboratory conventional impression scanning (LCIS). Each scan was saved in the STL file format. Using a computer program, each of the six digital models were compared with the reference model created by the CCM and the results were displayed as color maps. The minimal acceptable deviation was defined as the deviation from the digital standard within the ± 0.02 mm limits. Thus, the LSS group exhibited an average of 13.5% points within these limits, followed by the LCIS group with 17.25%. The result for the DIS group was 44.75%.
Laser annealing of bimetal porous structures produced by PLD in open air
Authors: Nikov Ru , Nikov Ro , Nedyalkov N , Dikovska A , Grochowska K 
Published: April 2022

Abstract
This work presents experimental results on laser annealing of bimetal structures produced by pulsed laser deposition in air at atmosphere pressure. The initial structures are deposited in open air by laser ablation of a rotating target consisting of two sections – Au and Ag. The ablation process is carried out by nanosecond pulses delivered by a Nd:YAG laser system emitting the wavelength of 355 nm. In open air, the laser ablation results in the formation of nanoparticles (NPs) and NP aggregates; during a prolonged deposition, these grow on the substrate into a 3D porous structure. The as-deposited structures are then annealed by laser pulses using the same laser system. The morphology of the annealed samples is studied in relation to the laser processing by varying the laser fluence and the number of the laser pulses. It is found that under certain conditions, the laser annealing leads to the formation of a 2D array of bimetal NPs on the substrate. The optical response of such structures composed by noble metals (such as Au and Ag) or their alloys is associated with a strong absorption in the visible spectral range known as surface plasmon resonance. Special attention is paid to the influence of the annealing parameters on the optical properties of the samples prepared.
Electrical characterization of memory capacitors for nonvolatile memory applications based on nanolaminated HfO2/Al2O3 and Al-doped HfO2 stacks
Authors: Spassov D , Paskaleva A , Stanchev T , Ivanov Tz 
Published: April 2022

Abstract
Memory capacitors with atomic-layer-deposited HfO2/Al2O3 nanolaminated layers and Al-doped HfO2 charge trapping layers were investigated through capacitance-voltage (C-V) and current-voltage (I-V) measurements. The dielectric constant of the multi-dielectric stack comprising 20-nm Al2O3 blocking oxide, a HfO2-based layer and 2.4-nm tunnel SiO2 does not depend on the manner of Al-introduction in HfO2.The stacks exhibit a negative oxide charge of about -5.1×1011 cm−2 and -2.5×1011 cm−2 for the structures with nanolaminated and doped layers, respectively. The Al-doping of HfO2 is found to produce lower leakage currents. A sublinear behavior of the current-voltage curves is observed in the range of -20 ÷ +10 V for both HfO2-based stacks. Memory windows of ∼ 1 V when charging with ±27-V voltage pulses are obtained; the data suggests that electron trapping is better pronounced in the HfO2/Al2O3 nanolaminate, while positive charge accumulation prevails in the Al-doped HfO2 layers.
Nanosecond laser ablation of nitride ceramics in liquid
Authors: Nikov Ro , Nedyalkov N , Nikova T , Aleksandrov L 
Published: April 2022

Abstract
The work presents results on nanosecond laser ablation of nitride ceramics immersed in a liquid medium. AlN and Si3N4 ceramic plates were used targets, and double distilled water was used as a liquid medium. Radiation of a nanosecond Nd:YAG laser system was used in the ablation process with the purpose of studying the influence of the laser fluence and number of pulses on the target surface morphology. The morphology and phase composition of the structured surfaces were explored by scanning electron microscopy and X-ray diffraction measurements, respectively. The optical properties of the obtained colloids were investigated by transmission measurements in the UV-Vis spectral ranges.
Time-of-flight methodologies with large-area diamond detectors for the effectively characterization of tens MeV protons
Authors: Salvadori M. , Andreoli P.L. , Cipriani M. , Cristofari G. , De Angelis R. , Malko S. , Volpe L. , Perez Hernandez J.A. , Apiñaniz J.I. , Morace A. , Antici P. , Migliorati M. , Di Giorgio G. , Consoli F. 
Published: April 2022

Abstract
A novel detector based on a polycrystalline diamond sensor is here employed in an advanced time-of-flight scheme for the characterization of energetic ions accelerated during laser-matter interactions. The optimization of the detector and of the advanced TOF methodology allow to obtain signals characterized by high signal-to-noise ratio and high dynamic range even in the most challenging experimental environments, where the interaction of high-intensity laser pulses with matter leads to effective ion acceleration, but also to the generation of strong Electromagnetic Pulses (EMPs) with intensities up to the MV/m order. These are known to be a serious threat for the fielded diagnostic systems. In this paper we report on the measurement performed with the PW-class laser system Vega 3 at CLPU (∼30 J energy, ∼1021 W/cm2 intensity, ∼30 fs pulses) irradiating solid targets, where both tens of MeV ions and intense EMP fields were generated. The data were analyzed to retrieve a calibrated proton spectrum and in particular we focus on the analysis of the most energetic portion (E > 5.8 MeV) of the spectrum showing a procedure to deal with the intrinsic lower sensitivity of the detector in the mentioned spectral-range.
Integration and commissioning of the ATLAS Muon-to-Central-Trigger-Processor Interface for Run-3
Authors: Perrella S. , Afik Y. , Armbruster A. , Czodrowski P. , Ellis N. , Haas S. , Koulouris A. , Kulinska A.M. , Marzin A. , Pauly T. , Ryjov V. , Sanfilippo L. , Simoniello R. , Spiwoks R. , Vichoudis P. , Wyzlinski M. , Wengler T. 
Published: April 2022

Abstract
The Muon-to-Central Trigger Processor Interface was completely redesigned as part of the ATLAS Level-1 trigger upgrade for Run 3 of the Large Hadron Collider. The new system is implemented as a single AdvancedTCA module, using three large state-of-the-art FPGAs and high-density fiber-optic modules. Trigger information from the muon trigger detectors are received through 208 high speed links, while 60 links are used to send processed trigger information to the L1 Topological Trigger Processor and the Central Trigger Processor. Extensive integration tests with all input and output systems have shown that the data transfer is stable and reliable. We present results from integration tests with connected sub-systems as well as commissioning of the Muon-to-Central Trigger Processor Interface in the ATLAS experiment.
Reconstructing past fossil-fuel CO2 concentrations using tree rings and radiocarbon in the urban area of Medellín, Colombia
Authors: Vásquez Marileny , Lara Wilson , del Valle Jorge I , Sierra Carlos A 
Published: April 2022

Abstract
To meet international and national commitments to decrease emissions of fossil fuels, cities around the world must obtain information on their historical levels of emissions, identifying hotspots that require special attention. Direct atmospheric measurements of pollution sources are almost impossible to obtain retrospectively. However, tree rings serve as an archive of environmental information for reconstructing the temporal and spatial distribution of fossil-fuel emissions in urban areas. Here, we present a novel methodology to reconstruct the spatial and temporal contribution of fossil-fuel CO2 concentration ([CO2F]) in the urban area of Medellin, Colombia. We used a combination of dendrochronological analyses, radiocarbon measurements, and statistical modeling. We obtained annual maps of [CO2F] from 1977 to 2018 that describe changes in its spatial distribution over time. Our method was successful at identifying hotspots of emissions around industrial areas, and areas with high traffic density. It also identified temporal trends that may be related to socioeconomic and technological factors. We observed an important increase in [CO2F] during the last decade, which suggests that efforts of city officials to reduce traffic and emissions did not have a significant impact on the contribution of fossil fuels to local air. The method presented here could be of significant value for city planners and environmental officials from other urban areas around the world. It allows identifying hotspots of fossil fuels emissions, evaluating the impact of previous environmental policies, and planning new interventions to reduce emissions.
Shifting concerns for the EU ETS: are carbon prices becoming too high?
Authors: Gerlagh Reyer , Heijmans Roweno J R K , Einar Rosendahl Knut 
Published: April 2022

AbstractCarbon prices in the EU Emissions Trading Scheme (EU ETS) have risen from around 5 euro per ton of CO2in 2017 to above 90 euro in 2021. One probable explanation is the cancellation mechanism implemented along with the Market Stability Reserve (MSR) of the EU ETS in 2018. We identify realistic conditions under which the MSR results in truly massive cancellation of emissions allowances, pointing to the steepness of the emissions pathway over time as essential. A flattening of the emissions pathway implies huge reduction in cumulative emissions, suggesting much higher ETS prices. The concerns about too low and ‘ineffective’ carbon prices may turn into concerns for too high prices. The results have important ramifications for planned revisions of the EU ETS.