bluuebunny/crossref_metadata_2025_split huggingface dataset:
A sequence-to-sequence remaining useful life prediction method combining unsupervised LSTM encoding-decoding and temporal convolutional network
Authors: Li Jialin , Chen Renxiang , Huang Xianzhen 
Published: March 2022

Abstract
Remaining useful life (RUL) prediction methods based on deep neural networks (DNNs) have received much attention in recent years. The collected time-series signals are usually processed by the sliding time window method into several segments with the same sequence length as the input. However, the signal processing is not only time-consuming, but also relies too much on personal experience. Moreover, the length of the time window affects the prediction results and the prediction range. Obviously, it is more desirable to remove the data processing and use an entire time series signal as the input for predicting the RUL, i.e. sequence-to-sequence RUL prediction. In order to remove the shortcomings of signal processing, this paper uses a long short-term memory (LSTM) and encoding-decoding framework to construct an unsupervised sequence data processing model. Then, a temporal convolutional network, based on a convolutional neural network, is used to further process the output data of the unsupervised sequence data processing model. The proposed sequence-to-sequence RUL prediction method not only maintains the complete sequence of the data, but has a good capability for data processing. The open access C-MAPSS simulation datasets are used for validation. The validation results show that the proposed method can realize unsupervised sequence signal reconstruction. Moreover, it has better prediction results and prediction efficiency.
Relativistic second-order initial conditions for simulations of large-scale structure
Authors: Adamek Julian , Calles Juan , Montandon Thomas , Noreña Jorge , Stahl Clément 
Published: April 2022

Abstract
Relativistic corrections to the evolution of structure can be used to test general relativity on cosmological scales. They are also a well-known systematic contamination in the search for a primordial non-Gaussian signal. We present a numerical framework to generate RELativistic second-order Initial Conditions (RELIC) based on a generic (not necessarily separable) second-order kernel for the density perturbations. In order to keep the time complexity manageable we introduce a scale cut that separates long and short scales, and neglect the “short-short” coupling that will eventually be swamped by uncontrollable higher-order effects. To test our approach, we use the second-order Einstein-Boltzmann code SONG to provide the numerical second-order kernel in a ΛCDM model, and we demonstrate that the realisations generated by RELIC reproduce the bispectra well whenever at least one of the scales is a “long” mode. We then present a generic algorithm that takes a perturbed density field as an input and provides particle initial data that matches this input to arbitrary order in perturbations for a given particle-mesh scheme. We implement this algorithm in the relativistic N-body code gevolution to demonstrate how our framework can be used to set precise initial conditions for cosmological simulations of large-scale structure.
The effect of He-induced surface microstructure on D plasma-driven permeation through RAFM steel
Authors: Wang Lu , Zhou Hai-Shan , Liu Hao-Dong , Qi Qiang , Tu Han-Jun , Shi Li-Qun , Luo Guang-Nan 
Published: March 2022

Abstract
The effect of helium (He)-induced surface microstructure on deuterium (D) plasma-driven permeation through a reduced activation ferritic/martensitic steel CLF-1 has been studied. CLF-1 steel was pre-exposed by He plasma with ion fluence of 1022–1024 He m−2 and an incident energy of 100 eV at 708 K. The following D plasma-driven permeation experiment was performed at 693 K. Steady-state D permeation flux decreases with the increase in He ion fluence. D diffusion coefficient is not significantly affected by He pre-damage, while D reflection coefficient increases with the enhancement of He ion fluence. Scanning electron microscope and transmission electron microscope analyses clearly reveal the evolution of surface roughness and He bubble layer after He plasma exposure. Elastic recoil detection was used to identify He concentration depth profiles in the samples. Both the surface microstructure modification and He bubble layer formation contribute to the reduction of D permeation.
Effect of laser annealing on the properties of Ag/ZnO nanostructures
Authors: Koleva M E , Dikovska A O , Nedyalkov N N , Karashanova D 
Published: April 2022

Abstract
Ag/ZnO nanostructures were synthesized using pulsed laser deposition (PLD) in open air (at atmospheric pressure). The deposition was carried out by a Nd:YAG laser, with the Ag layer composed of nanoparticles grown on SiO2 (001) substrates by the laser wavelength of 355 nm; this layer was covered by ZnO deposited by using the laser wavelength of 1064 nm. The samples were laser annealed, which led to a modification of the nanoparticles. The nanocomposites produced were characterized by TEM, UV-Vis and PL spectroscopy. The annealing procedures influence the optical properties of the Ag/ZnO nanocomposites. The laser annealing under certain parameters changes the emission behavior of the Ag/ZnO nanocomposite heterostructures. By employing localized surface plasmon resonance (LSPR), the near band edge (NBE) emission intensity of the ZnO films composed of nanoparticles was varied. An enhancement of the UV emission located at about 383 nm, commonly attributed to an excitonic transition, was registered after laser annealing with one pulse at the wavelength of 355 nm. The results obtained demonstrate that the annealing of Ag/ZnO composite nanostructures plays a key role in tuning the PL performance of a semiconductor material where an LSPR occurs.
Formation and characterization of CuO coatings deposited by reactive magnetron sputtering
Authors: Ormanova M , Kotlarski G , Valkov S , Dechev D , Ivanov N , Petrov P 
Published: April 2022

Abstract
In this work, CuO coatings were deposited on 304 L stainless steel substrates by reactive magnetron sputtering. During the process, the substrate temperature was varied in the range from 100 °C to 400 °C. The crystallographic structure of the samples thus prepared was characterized by X-ray diffraction, and the results are discussed with respect to the technological conditions applied. It was found that the phase composition of the deposited CuO coatings is in the form of a monoclinic crystal structure. Also, the growth of the coatings was accompanied by a change in the orientation of the crystallites from (022) to (110) and a decrease in the concentration of imperfections.
Spectral readout of SPR excited in diffraction grating
Authors: Belina E , Mankov V , Kisov H , Dimitrova T L , Dyankov G 
Published: April 2022

Abstract
The surface plasmon resonance (SPR) sensing has emerged as a powerful tool for measuring the binding of analytes to functionalized surfaces and immobilized (bio)molecules. We describe the development of a grating for spectral readout of SPR excited in a diffraction grating. The SPR chips based on a metallized diffraction grating have two main problems: undesired reflection from the non-metallic substrate and the half-width of the resonance curve, which determines the accuracy of the SPR sensors [1]. In this report, we demonstrate that a few metal layers with a fixed thickness deposited on a polycarbonate substrate in a certain sequence represent a structure as required for high-quality SPR chips. The structure can provide correct spectral readout, which was confirmed by our numerous experiments. Also, the layers deposition can be performed in one technological step by sputtering or by thermal evaporation in vacuum. We discuss the dependence of the SPR parameters on the multilayer structure parameters.
Extraction of accompanying metals through electron beam refining of copper
Authors: Vassileva V , Vutova K , Markov M 
Published: April 2022

Abstract
This work presents a study on applying the electron beam method for refining pyro-refined copper (as initial material) and obtaining multiple metals through electron beam melting. Studies of and results on the refining processes under different technological modes are presented and discussed. The experiments were performed in single-melt operations with different e-beam power inputs and refining times. Evaluation is provided concerning the extraction of some valuable metals (such as Ni, As, Bi, Pb, Sb, Ag) generated in the condensate during their removal from the liquid metal in the e-beam refining process.
Coherent optical spectroscopy characterization of the magnetic properties of oriented Fe3O4 nanoparticles
Authors: Taskova E , Alipieva E , Kolev S , Koutzarova T , Brazhnikov D 
Published: April 2022

Abstract
Magnetite (Fe3O4) nanoparticles are widely used in microwave components, such as microwave absorbers and anti-reflection coatings. Their magnetic properties are important for these applications. In this work, the weak magnetic field created by the Fe3O4 nanoparticles was estimated using a coherent-spectroscopy all-optical method for measurement of weak magnetic fields. Both the magnitude and the direction of the magnetic field were evaluated through the position and amplitude of a magneto-optical resonance obtained in a paraffin-coated sensor cell containing Rb vapors. A pump-probe scheme was used to prepare a high-contrast magneto-optical resonance. Different possible geometries related to this concept are discussed, including sensor miniaturization.
Design of a plasmonic sensor based on a nanosized structure for biochemical application
Authors: Salah Hocine Ben , Bahri Hocine , Hocini Abdesselam , Zegaar Imane , Ingebrandt Sven , Pachauri Vivek 
Published: April 2022

Abstract
A novel design of an integrated ring cavity consisting of two merged and opposite triangles formed on a metal-insulator-metal (MIM) waveguide is suggested and analyzed for refractive index sensing application. The cavity design can be optimized provide the best sensing performance. In this work, we simulated numerically the device design by utilizing the finite-difference-time-domain (FDTD) technique in a two-dimensional (2D) structure. The detection of the refractive index changes was numerically simulated and analyzed using RSoft™. Small variations in the geometric parameters can enhance the sensitivity achieved, which we found to be 3575 nm/RIU. We believe that the sensor can achieve a resolution of 2.79×10−6. The structure proposed has a simple design for easy and compact realization, paving the way of detecting rare biochemical analytes and for finding applications in optical filters.
Thermodynamic analysis of the processes during electron beam melting and refining of copper
Authors: Stefanova V , Vutova K , Vassileva V 
Published: April 2022

Abstract
In the paper, results are presented and discussed obtained by thermodynamic analysis of the refining processes of copper aimed at removing metal impurities and oxygen via electron beam melting (EBM) in vacuum. Thermodynamic evaluations of the possible chemical interactions between the base metal (Cu) and the metal impurities present in Cu that can proceed during the refining of copper are made based on the calculated values of the Gibbs free energy and equilibrium constants taking into account the physical state of copper and of the metal impurities during EBM.
Simulations of a capacitor with graphene electrodes
Authors: Vachkov V , Kiss’ovski Zh 
Published: April 2022

Abstract
In this work, the behavior of a graphene-based capacitor was investigated by using an electromagnetic (EM) simulator. The graphene electrodes were simulated as a porous structure with a varying pore diameter as derived from experimental data. The main issue in modeling such a structure is the large number of objects with nano- or micro-dimensions (∼millions), which imposes a significant computation challenge for the simulator. A solution was developed by introducing an externally created matrix of the electrode with a fixed number of elements, which allowed the successful and accurate simulation of the complex porous-based structure. The pores of the electrodes are modeled as cylindrical holes in a solid graphene parallelepiped, while the capacitance is determined for different dimensions of pores of electrodes with a corresponding shape of the dielectric medium. The results obtained show a significant increase in the capacitance compared to a capacitor with flat metal electrodes.
Model-based multicriterial optimization of electron beam melting and refining of copper
Authors: Koleva E , Koleva L , Vassileva V , Vutova K , Tsonevska Ts 
Published: April 2022

Abstract
Experimental results on the quality of electron beam melting and refining of copper samples by implementing the “method of washers” are analyzed by using an empirical model estimation approach. The influence is studied of the process parameters – melting power and time of refining, on the residual content of impurities, the refining rate, the overall removal efficiency and the material losses. A graphical user interface is designed and developed for calculation, investigation and multicriterial optimization of the quality of the refined copper samples.
Altering the surface morphology and wettability of chitosan/graphene coatings by femtosecond and nanosecond laser processing
Authors: Filipov E , Angelova L , Aceti D , Marinova V , Karashanova D , Trifonov A , Buchvarov I , Daskalova A 
Published: April 2022

Abstract
A major drawback of the currently used orthopedic implants is the formation of a bacterial biofilm on their surface after implantation. A potential strategy for overcoming this problem is developing micro- and nano-structured motifs on the implant’s surface to prevent bacterial attachment. Additionally, the use of materials with inherent antimicrobial properties could further stall the aggregation of bacteria. This paper demonstrates an approach to obtaining a modified surface topography on chitosan-graphene 2D films via femtosecond and nanosecond laser treatment. Atomic force microscopy (AFM) revealed that laser irradiation leads to a strong surface roughness increase due to formation of non-ordered topography features with peak-to-valley distance ranging between 200 nm and 1 μm. Interestingly, sharp single protrusions (∼200 nm) were observed on the untreated samples. Transmission electron microscopy analysis confirmed the presence of graphene monolayers within the composite films. Wettability tests showed that nanosecond laser ablation of the samples resulted in super hydrophilic surface properties, which repel bacteria per se. Based on our findings, we hypothesized that the topography motifs of both laser treated and untreated samples could potentially impede bacterial attachment via different mechanisms – reduction of contact points for adhesion or restriction of motility.
Ultra-fast laser modification of poly-lactic acid (PLA) -towards enhanced biocompatibility
Authors: Angelova L , Daskalova A , Mincheva R , Carette X , Trifonov A , Filipov E , Aceti D , Buchvarov I 
Published: April 2022

AbstractIn this study, the interaction was investigated of femtosecond laser radiation (pulse duration τ = 130 fs, wavelengthλ= 800 nm) with poly-lactic acid (PLA) 2D scaffolds. Two sets of laser fluences(F)and scanning speed(V)values were applied to PLA matrices -F= 1.66 J/cm2,V= 3.8 mm/s, andF= 0.83 J/cm2,V= 3.8 mm/s. The PLA samples thickness, roughness, and water contact angle (WCA) were characterized before and after the laser structuring. The fs-induced micro structures were investigated by SEM, EDX, and FTIR analyses. Preliminary cell fibroblast studies were performed. The results obtained clearly show that a precise laser surface structuring could orient the cells matrix ingrowth and thus make PLA bone tissue engineering interbody future application more successful and adaptable to the personal needs of the recipients.
Laser processing of nitride ceramics
Authors: Nedyalkov N , Dilova T , Dikovska A , Nikov Ru , Nikov Ro , Koleva M , Stankova N , Daskalova Al , Angelova L 
Published: April 2022

Abstract
In this work, the surface modifications are studied of aluminium nitride (AlN) and silicon nitride (Si3N4) ceramics irradiated by nanosecond laser pulses. The laser processing is performed by a Nd:YAG laser system at four wavelengths - 266 nm, 355 nm, 532 nm, and 1064 nm. It is found that the average ablation rate per pulse is in the order of few hundreds of nanometers, as the laser treatment leads to the appearance of a variety of micro- and nanostructures on the surface of the material. In the case of AlN, a conductive layer is formed on the surface whose resistance can be modified by varying the processing conditions. Using a model based on the heat-conduction equation, the temperature evolution, ablation depth and temporal dynamics of the ablation process are followed.
Study of neutron irradiation effects in Depleted CMOS detector structures
Authors: Mandić I. , Cindro V. , Debevc J. , Gorišek A. , Hiti B. , Kramberger G. , Skomina P. , Zavrtanik M. , Mikuž M. , Vilella E. , Zhang C. , Powell S. , Franks M. , Marco-Hernandez R. , Steininger H. 
Published: March 2022

Abstract
In this paper the results of Edge-TCT and I-V measurements
with passive test structures made in LFoundry 150 nm HV-CMOS process
on p-type substrates with different initial resistivities ranging
from 0.5 to 3 kΩcm are presented. Samples were irradiated
with reactor neutrons up to a fluence of
2·1015 neq/cm2. The depletion depth was
measured with Edge-TCT. The effective space charge concentration
Neff was estimated from the dependence of the
depletion depth on bias voltage and studied as a function of neutron
fluence. The dependence of Neff on fluence changes
with initial acceptor concentration in agreement with other
measurements with p-type silicon. A long term accelerated annealing
study of Neff and detector current up to 1280 minutes
at 60°C was made. It was found that Neff and
current in reverse biased detector behave as expected for irradiated
silicon.
Installation, integration and first operating experiences of the ALICE ITS upgraded readout system
Authors: Groettvik O. 
Published: April 2022

Abstract
The ALICE inner tracking system has gone through a significant upgrade for the upcoming third running period of the CERN LHC. The new detector consists of seven layers of high-granularity pixel sensors, while 192 custom FPGA-based readout units control the sensors and transmit the data upstream for analysis. This contribution describes the current system status and the expertise gained by moving from surface commissioning to the installation and throughout the data-taking preparation period, focusing on the intricate integration with other system components. Selected challenges, issues, and lessons learned during the various commissioning periods are presented.
The influence of thinning and prescribed burning on future forest fires in fire-prone regions of Europe
Authors: Rabin S S , Gérard F N , Arneth A 
Published: March 2022

Abstract
Climate change is expected to increase fire risk in many forested regions, posing a potential threat to forest functioning (i.e. carbon pools and fluxes). At the same time, expansion of the wildland-urban interface threatens to bring more and more people, property, and infrastructure into contact with wildfire events. It is critical that fire be managed in a way that minimizes risk to human health and well-being and maintains forest climate change mitigation potential without affecting the important ecological role fire plays in many ecosystems. Dynamic global vegetation models (DGVMs) simulate processes over large geographic regions and long time periods and could provide information that supports fire and fuel management programs by assessing performance of such measures under different climate change scenarios in different regions. However, thus far DGVMs have not been put to this use. In this work, we introduce a novel prescribed burning (PB) module to the LPJ-GUESS DGVM. Focusing on two regions (Eastern Europe and the Iberian Peninsula), we compare the effectiveness of PB and mechanical thinning on various aspects of the fire regime under two climate change scenarios through the end of the 21st century. We find that PB and thinning, by reducing fuel load, reduce fireline intensity; this suggests that what wildfires do occur could be more easily controlled. While this would reduce risks to human health and well-being, PB comes with the tradeoff of increased fire emissions, which could contribute to respiratory problems. Mechanical thinning reduces fireline intensity by as much or more while also reducing emissions. While net primary production remained unaffected by fire management, cumulative net biome production until the end of the 21st century declined especially under the influence of thinning. While these results are based on stylized management treatments, this work shows the potential of DGVMs in exploring fire management options.
The unrecognized importance of carbon stocks and fluxes from swamps in Canada and the USA
Authors: Davidson Scott J , Dazé Emily , Byun Eunji , Hiler Dean , Kangur Markus , Talbot Julie , Finkelstein Sarah A , Strack Maria 
Published: April 2022

Abstract
Swamps are a highly significant wetland type in North America both in terms of areal extent and their role in terrestrial carbon cycling. These wetlands, characterized by woody vegetation cover, encompass a diverse suite of ecosystems, including broad-leaved, needle-leaved, mixedwood or shrub/thicket swamps. Uncertainties in the role of swamps in carbon uptake and release continue to be substantial due to insufficient data on variabilities in carbon densities across diverse swamp types and relatively few flux measurements from swamp sites. Robust measurements of rates of vertical accretion of swamp soils and the associated long-term rates of carbon accumulation, alongside measurements of carbon losses from swamps, are needed for emerging frameworks for carbon accounting, and for assessments of the impacts of climate warming and land use change on this important wetland type. Based on data compilation, we present here a comparative analysis from a series of North American swamp sites on carbon dioxide, methane and dissolved organic carbon fluxes, aboveground biomass, net primary productivity (NPP), and soil carbon properties including bulk densities, organic carbon contents, peat depths, rates of vertical accretion, and rates of long-term carbon accumulation. We compare these properties for four major swamp types: needle-leaved, broad-leaved, mixedwood and shrub/thicket swamps. We show differences in carbon fluxes, biomass and NPP across the four types, with broad-leaved swamps having the largest CH4 flux, highest soil bulk densities, thinnest peat depths and lowest soil organic matter contents, whereas needle-leaved swamps have the smallest CH4 flux, highest aboveground biomass and highest NPP. We show high soil carbon stocks (kg C m−2) in all types of swamps, even those where organic deposits were too shallow to meet the definition of peat. However, we note there is a significant lack of studies focused on swamp carbon dynamics despite their abundance across Canada and the United States.