Layers Of Different Thicknesses Research Articles

Second-Order Dispersion Sensor Based on Multi-Plasmonic Surface Resonances in D-Shaped Photonic Crystal Fibers

This paper proposes a scheme to determine the optical dispersion properties of a medium using multiple localized surface plasmon resonances (SPR) in a D-shaped photonic crystal fiber (PCF) whose flat surface is covered by three adjacent gold layers of different thicknesses. Using computational simulations, we show how to customize plasmon resonances at different wavelengths, thus allowing for obtaining the second-order dispersion. The central aspect of this sensing configuration is to balance miniaturization with low coupling between the different localized plasmon modes in adjacent metallic nanostructures. The determination of the optical dispersion over a large spectral range provides information on the concentration of different constituents of a medium, which is of paramount importance when monitoring media with time-varying concentrations, such as fluidic media.

The theoretical-empirical technique of hydrocarbons prediction in wells sections. New aspects

We present the developed theoretical-empirical technique for predicting of rocks’ oil-and-gas bearing in wells sections according to acoustic logging (AL) and core research (CR) and its variants by using data of other loggings and also the results of testing them on wells sections data in the Western oil and gas bearing region of Ukraine (WOGR). The mathematical apparatus of the created technique is based on a mathematical model of solid porous rock, empirical relationships between elastic and reservoir characteristics of rocks and acoustic logging data for specific studied wells. The key parameter in the calculations is the rock compressibility. Determination of the porosity of rocks and prediction of the type of pore filler (water, oil, gas) is implemented by comparing the results of calculating the velocities using theoretical and constructed empirical relationships with the actual data of the AL, by the parameter of compressibility of rocks, by the density of the pore filler fluid. Additional versions of the technique have been developed based on correlation dependences and data from other logging methods — gamma-ray logging (GL), electric logging (EL/SP), offset method and seismic logging (SL). They are used in case of absence of AL data for the studied wells or for the intervals of their sections, and also for improving the reliability of prediction the oil and gas content of these sections. The software for the implementation of the technique was developed in Fortran, C# and Excel software environments. The technique was tested on the data of wells of a number of structures of the WOGR of Ukraine (Lishchyns’ka, Buchats’ka, Ludyns’ka, Zaluzhans’ka, Zarichnyans’ka and Nyklovyts’ka).The technique ensures reliable prediction of petrophysical characteristics, porosity and oil-gas-water saturation of rock layers of different thicknesses (including thin layers — from 0.1—0.2 m) in well sections. For this, in addition to the data of the general parametric base of the WOGR reservoir rocks, the specially constructed refined empirical relations for various specific types and subtypes of the WOGR reservoir rocks are used, they are based on the results of analysis of petrophysical characteristics of those rocks.

Galvanic Sensor for Detecting Corrosion during Acid Cleaning of Magnetite in Steam Boilers

A simple galvanic sensor was developed to determine the onset of iron corrosion under conditions similar to those used for removing the iron oxide (magnetite) layer from steam boilers with a hy-drochloric acid solution. Since the potentials of magnetite and iron are different, the initiation of the dissolution of the magnetite layer without corroding the base metal can be determined by moni-toring the potential of a sensor made of magnetite layers of different thicknesses that can be placed directly on the iron surface. Moreover, the time at which the addition of corrosion inhibitors is required to protect the base metal can be specified using this sensor. It has been shown that the time required for the iron base metal to start was dependent on the magnetite layer thickness in the sensor. With this sensor, the onset of the steel corrosion during the cleaning can be detected in re-al-time which makes the oxide removal process less harmful to the base metal.

Tunable absorber embedded with GST mediums and trilayer graphene strip microheaters

Investigation was made of the optical response of metal-dielectric stacks-based cavity structures embedded with graphene microheaters for the purpose of perfect absorption. The absorber configuration exploits the Ge2Sb2Te5 (GST) phase changing medium, and the effects of different parametric and operational conditions on the absorption spectra were explored. The refractive indices of GST layers can be manipulated by the external electrical pulses applied to microheaters. The amplitude and duration of electrical pulses define the crystallinity ratio of the used GST mediums. The results revealed achieving perfect absorption (> 99%) in the visible and infrared (IR) regimes of the electromagnetic spectrum upon incorporating two thin GST layers of different thicknesses (in the stack) in the amorphous state. The proposed configuration showed the capability of introducing independent transition state (amorphous and/or crystalline) for each GST layer—the visible regime could be extended to the IR regime, and the perfect absorption peak in the IR regime could be broadened and red-shifted. It is expected that the structure would find potential applications in active photonic devices, infrared imaging, detectors and tunable absorbers.

Electrospun Janus fabrics with directional water transport property for efficient water collection

Collection of clean water from humid air has attracted immense attention in recent years. Janus fabrics (JFs) have been widely employed to harvest fog droplets. Herein, a double-layer hydrophilic/hydrophobic Janus fabric was prepared by depositing polystyrene (PS) layers of different thicknesses on hydrophilic cotton fabric via one-step electrospinning technology. The thickness of the PS layer and the distance from the fog outlet to the fabric surface affected the water collection rate (WCR). The water collection rate of the JFs initially increased and then decreased as the thickness of the PS layer was increased. Benefiting from the timely drainage and directional droplet delivery, the JFs showed a 147% enhancement in the WCR compared with hydrophilic cotton fabric. This work may provide insight into the design and fabrication of fog collection systems with high efficiency to alleviate the freshwater crisis.

Probing negatively charged and neutral excitons in MoS2/hBN and hBN/MoS2/hBN van der Waals heterostructures

High-quality van der Waals heterostructures assembled from hBN-encapsulated monolayer transition metal dichalcogenides enable observations of subtle optical and spin-valley properties whose identification was beyond the reach of structures exfoliated directly on standard SiO2/Si substrates. Here, we describe different van der Waals heterostructures based on uncapped single-layer MoS2 stacked onto hBN layers of different thicknesses and hBN-encapsulated monolayers. Depending on the doping level, they reveal the fine structure of excitonic complexes, i.e. neutral and charged excitons. In the emission spectra of a particular MoS2/hBN heterostructure without an hBN cap we resolve two trion peaks, T1 and T2, energetically split by about 10 meV, resembling the pair of singlet and triplet trion peaks (T S and T T ) in tungsten-based materials. The existence of these trion features suggests that monolayer MoS2 has a dark excitonic ground state, despite having a ‘bright’ single-particle arrangement of spin-polarized conduction bands. In addition, we show that the effective excitonic g-factor significantly depends on the electron concentration and reaches the lowest value of −2.47 for hBN-encapsulated structures, which reveals a nearly neutral doping regime. In the uncapped MoS2 structures, the excitonic g-factor varies from −1.15 to −1.39 depending on the thickness of the bottom hBN layer and decreases as a function of rising temperature.

Study of magnetic and transport properties of Bi2Se3/FeSe2 bilayer thin films

Thin films of topological insulator (TI) Bi2Se3 were grown onto the surfaces of FeSe2 layers of different thicknesses on Si (100) substrates by magnetron sputtering, forming bilayer films with smooth surface. Magnetic and transport measurements indicate ferromagnetism in these bilayer samples. Large coercive fields at low-temperatures and a room-temperature magnetic order were observed. Moreover, nonsaturated high-filed linear magnetoresistance (MR) and weak anti-localization effect were found in these bilayer thin films. These results indicate that the bilayer samples could have both strong spin–orbit coupling and ferromagnetic proximity effect, which are the desired features.

Non-destructive depth-dependent morphological characterization of ferroelectric:semiconducting polymer blend films

Herein, we investigate the technologically relevant blend of the ferroelectric polymer poly(vinylidene fluoride-co-trifluoroethylene), P(VDF-co-TrFE), with the semiconducting polymer poly(3-hexylthiophene), P3HT, by means of a combination of scanning probe microscopy techniques, namely atomic force microscopy, conductive force microscopy, kelvin probe force microscopy, and piezoresponse force microscopy. This combination proves to be a powerful tool for the non-destructive morphological reconstruction of multi-functional nano-structured thin films, as those under study. Each modality allows discerning the two blend constituents based on their functionality, and, additionally, probes layers of different thickness with respect to the film surface. The depth-dependent information that is collected allows a qualitative reconstruction of the blend’s composition and morphology both in-plane and out-of-plane of the film. We demonstrate that P3HT exhibits the tendency to reside the film surface at an almost constant composition of 15%, independent of blend’s composition. Increasing the P3HT content in the blend results in the segregation of P3HT at the upper layers of the films, partially buried below a P(VDF-co-TrFE) superficial layer. The depletion of P3HT from the substrate/film interface is reflected by the poor existence of conducting pathways that connect the top and bottom planes of the film. The three-dimensional morphology of this polymer blend that is revealed thanks to the employed techniques deviates substantially from the ideal morphology proposed for the efficient performance of the targeted memory devices.

Прогнозирование возможности продолжения эксплуатации самотечных сетей водоотведения с отложениями в лотковой части труб

In this work, the formula for forecasting the continued operation of gravity drainage networks with deposits in pipe water troughs is deduced and refined. In the authors' opinion, such a forecast should be based on the hydraulic principle for assessing the efficiency of a network operation, as the most accurate. To this end, the concept associated with the efficiency of gravity drainage networks was introduced, and a criterion for its assessment was proposed. In the study, the characteristics of hydraulic potential for concrete pipes with a diameter of 400 mm were calculated as an example. An empirical formula was proposed for determining the efficiency factor of the gravity drainage network, and its deviation range was shown. It was concluded that the expert prognosis of continued operation of gravity drainage networks should be based on the efficiency factor of the network, calculated using the obtained formula. It is recommended that a method for calculating an efficiency factor describing gravity drainage networks and special tables for the hydraulic calculation of pipes having a sediment layer of different thicknesses be elaborated. The data presented in the article allow servicing of gravity drainage network to be improved by forecasting its continued operation using the efficiency factor К_ef.

Экситонная люминесценция двойных монослоев CdTe в матрице ZnTe

A series of ZnTe matrix containing two CdTe monolayers separated by barrier layers of different thicknesses is studied. The dependences of the energies of the exciton emission bands related to the CdTe monolayers, their relative intensities, and temperature behavior on the thickness of the ZnTe barrier layer are determined. It is established that CdTe monolayers can be considered independent of each other with a barrier layer thickness of more than 30 monolayers.

Чисельне моделювання термо-напружено-деформованого стану елементів у процесі 3D друку

The paper is devoted to the assessment of the thermo-stress-strain state of elements of structures obtained by 3D printing using FDM (Fusing Deposition Modeling) technology. Three stages of solving this problem are considered: (1) - mathematical formulation of the problem, that includes universal balance relations, constitutive equations of mechanical behavior of the material and is based on the model of growing bodies; (2) the technique of finite-element solution with increasing mesh due to the addition of new elements; (3) - study of a specific problem of growing plate-like element by polymer PLA (polylactide) with temperature-dependent physical properties. Options of deposed layers of different thickness are considered. The residual stress-strain state of the body has a two-scale structure, which reflects the change of state characteristics in the scale of body size, as well as the thickness of the layers. As the thickness of the layers increases, the average values of the residual stresses decrease, but the amplitude of the stress fluctuations along the thickness of the layer slightly increase.

РАЗРАБОТКА И ПРИМЕНЕНИЕ ТЕХНОЛОГИЧЕСКИХ В ЦИФРОВОМ ПРОИЗВОДСТВЕ

The analysis of the current situation and prospects for developing additional technologies for IT production presents a new development paradigm, Industry 4.0. In addition to learning the techniques to acquire the product, additional manufacturing processes may require IT development of the model. For multi-layer manufacturing techniques, angle cuts at the edges are used to provide an algorithm for dividing the product into layers of different thickness. Computer design is considered a combination of complex engineering products, complex automation technologies, and engineering product assembly. Considering the use of 5-axis manipulators in the context of complex automatic cutting, the design of the plate and layer cutting process can be used differently with the example of synthesizing complex engineering products.

Peculiarities of the development of ionization instability of various scales in the air gas discharge

In this work, the air gas discharge of constant voltage, organized in an unlimited chamber without the side walls, is experimentally studied, which leads to a stratification of the discharge region due to the development of ionization instability. Depending on the conditions of the discharge (pressure or magnitude of the gas discharge current), the scale of the ionization striations changes, which leads to the layered structure of the plasma medium and the possibility of creating layers of different thicknesses, where not only the electronic temperature, but also the gas temperature are different. Various types of discharge were obtained in the work, from large-scale structured ones (3-5 striations per discharge length) to small-scale ones (20-25 striations per discharge length), and the conditions for their occurrence and development were investigated. The main diagnostic parameters are gas pressure, the magnitude of the gas discharge current, which is changed by a change in the load resistance, the size and frequency of the ionization waves, estimation of electronic and gas temperatures at different points of the discharge. Gas discharges of this kind can be used to structuring the air environment, gas mixing and supersonic flows control.

A polymer-film inertial microfluidic sorter fabricated by jigsaw puzzle method for precise size-based cell separation

A polymer-film inertial microfluidic jigsaw (PIMJ) sorter with trapezoidal spiral channels using the jigsaw puzzle method was proposed to realize precise and high-throughput rare cell separation. The PIMJ sorter was fabricated by assembling laser-patterned polymer-film layers of different thicknesses. After illustrating the conceptual design and fabrication process, the effects of the cross-sectional dimension, particle size, and operational flow rate on particle focusing were systematically explored under a broad flow rate range. Then, the separation performances of the PIMJ sorter were characterized using the binary particle mixture and the blood samples spiked with four types of tumor cells. The results indicated that the complete separation of the binary particles with a minimum size difference of 2 μm was successfully realized at a high throughput up to 3000 μL/min. A high recovery ratio of 90.57%-94.14% and a high purity of 48.67%-79.05% were achieved for the separation of rare tumor cells from white blood cells (WBCs). Finally, the PIMJ sorter was successfully employed for separating rare circulating tumor cells (CTCs) from the metastatic breast and lung cancer patients with a capture ratio of 7–226 CTCs per 5 mL sample. The results proved the high sensitivity and high reliability of the PIMJ sorter. The PIMJ sorter is expected to be a potential device for precise CTC separation towards the clinical applications.

Protection Mechanism against Photocorrosion of GaN Photoanodes Provided by NiO Thin Layers

The photoelectrochemical properties of n‐type Ga‐polar GaN photoelectrodes covered with NiO layers of different thicknesses in the range 0–20 nm are investigated for aqueous solution. To obtain layers of well‐defined thickness and high crystal quality, NiO is grown by plasma‐assisted molecular‐beam epitaxy. Stability tests reveal that the NiO layers suppress photocorrosion. With increasing NiO thickness, the onset of the photocurrent is shifted to more positive voltages and the photocurrent is reduced, especially for low bias potentials, indicating that hole transfer to the electrolyte interface is hindered by thicker NiO layers. Furthermore, cathodic transient spikes are observed under intermittent illumination, which hints at surface recombination processes. These results are inconsistent with the common explanation of the protection mechanism that the band alignment of GaN/NiO enables efficient hole‐injection, thus preventing hole accumulation at the GaN surface that would lead to anodic photocorrosion. Interestingly, the morphology of the etch pits as well as further experiments involving the photodeposition of Ag indicate that photocorrosion of GaN photoanodes is related to reductive processes at threading dislocations. Therefore, it is concluded that the NiO layers block the transfer of photogenerated electrons from GaN to the electrolyte interface, which prevents the cathodic photocorrosion.

Soil Anisotropicity in Modern Methods of Ground Bases Calculating

Calculation sequence of soil bases for deformations, taking into account their deformation anisotropy provided in the article. The calculations were performed by the finite element method using the mathematical planning method of the experiment. After determining the deformation anisotropy index of the soil, it was established the possibility to use the numerical experiment results within the tables of the soil anisotropy coefficients of influence, to calculate the soil base sediment and layers of different thicknesses using a currently existing methods, taking into account their deformation anisotropy. It was revealed that the deformation anisotropy nature of the soils’ studied types is different: for plastic sandy loam the indicator was α ≤ 1; for loess like sandy loams and loams, as a rule, α > 1; for sands of medium density and dense, tested under compression was α < 1. Together with an increase in the compressive load, a value increase, and with an increase in a, the foundation sediments’ values increase. Taking into account the soils’ natural anisotropy makes it possible to more reasonably assign the sizes of the foundations soles and determine their settlement, and in some cases to obtain a noticeable economic effect.

Non-Invasive and Spectroscopic Techniques for the Study of Alonso Cano's Visitation from the Golden Age of Spain

ABSTRACT Alonso Cano is considered one of the most original and brilliant artists from the Spanish Golden Age (known in Spanish as Siglo de Oro), a period of flourishing in arts and literature. He was also the founder of the Baroque painting school of Granada. This paper focuses on the painting the Visitation painted by Cano in 1652 and housed in the main chapel of Granada Cathedral. This study is part of an ambitious 11-year project aimed at understanding Cano's working technique by considering both the evolution of his painting style and the reconstruction of his color palette. Through this extensive project we intended to provide necessary scientific evidence to help in authorship verification in cases of controversial attribution to Cano of paintings included in the current catalogue of the artist. To this end, the Visitation was included in the project and a series of non-invasive and minimally invasive analytical techniques were applied to gain a wider insight into the artist's technique and the materials used to create his paintings. Macroscopic and microscopic examination of the surface, infrared reflectography, ultraviolet fluorescence, and X-radiography were performed. The underdrawings found reveal some significant changes in the composition of the figures. The results of optical microscopy, UV fluorescence microscopy, and scanning electron microscopy revealed a quasi-sculptural treatment of the figures, where the artist tested different pigment:binder ratios and applied several pictorial layers of different thicknesses. SEM with energy dispersive X-ray spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, and micro-Raman spectrometry were used to identify the pigments present in individual layers. The results showed that pigments generally available in the seventeenth century were used, including white lead, malachite, copper resinate, vermilion, red lake, lapis lazuli, smalt, red lead, bone black, and carbon black. Additionally, gas chromatography-mass spectrometry analysis suggested the use of linseed oil binding medium.

Analysis of the Contribution Rate of the Influencing Factors to Land Subsidence in the Eastern Beijing Plain, China Based on Extremely Randomized Trees (ERT) Method

As a common geological hazard, land subsidence is widely distributed in the Eastern Beijing Plain. The pattern of evolution of this geological phenomenon is controlled by many factors, including groundwater level change in different aquifers, compressible layers of different thicknesses, and static and dynamic loads. First, based on the small baseline subset Interferometric Synthetic Aperture Radar (SBAS-InSAR) technique, we employed 47 ENVISAT ASAR images and 48 RADARSAT-2 images to acquire the ground deformation of the Beijing Plain from June 2003 to November 2015 and then validated the results using leveling benchmark monitoring. Second, we innovatively calculated additional stress to obtain static and dynamic load information. Finally, we evaluated the contribution rate of the influencing factors to land subsidence by using the Spearman’s rank correlation coefficient (SRCC) and extremely randomized trees (ERT) machine learning methods. The SBAS-InSAR outcomes revealed that the maximum deformation rate was 110.7 mm/year from 2003 to 2010 and 144.4 mm/year from 2010 to 2015. The SBAS-InSAR results agreed well with the leveling benchmark monitoring results; the correlation coefficients were 0.97 and 0.96 during the 2003–2010 and 2013–2015 periods, respectively. The contribution rate of the second confined aquifer to the cumulative land subsidence was 49.3% from 2003 to 2010, accounting for the largest proportion; however, its contribution rate decreased to 23.4% from 2010 to 2015. The contribution rate of the third confined aquifer to the cumulative land subsidence increased from 2003 to 2015. Although the contribution of additional stress engendered from static and dynamic loads to the cumulative land subsidence was slight, it had a significant effect on the uneven land subsidence, with a contribution rate of 33.8% from 2003 to 2010 and 23.1% from 2010 to 2015. These findings provide scientific support for mitigating hazards associated with land subsidence.

Application of geocell reinforced coal mine overburden waste as subballast in railway tracks on weak subgrade

An alarming volume of coal mining by-product in the form of waste rock, referred to as overburden (OB), is being dumped over vast areas of useful ground, leading to an ever-increasing demand for land space worldwide. Reusing this material in the form of industrial applications can provide an effective and environmentally sound solution for disposal of the unsightly and polluted stockpiles. The present study focuses on recycling the coal mine OB as an alternative to conventional subballast material in railways. A series of model tests have been conducted with the OB material as subballast layers of different thicknesses overlying a weak subgrade. Further, geocells of varying geometries have been used for additional performance improvement. The results portrayed that coal OB had the potential to be recycled as a subballast material in railways. Additionally, with geocell reinforced OB, the magnitude of vertical settlement and stresses in the track bed can be reduced significantly. Experimentally validated finite element models (FEM) were used to predict the lateral deformations and subgrade stresses in the track bed, which were also found to have exhibited substantial reductions with geocell reinforcement.

Reading depth of the magnetic Barkhausen noise. II. Two-phase surface-treated steels

This second part of the work estimates the reading depth of the magnetic Barkhausen noise, testing surface-treated steels. The concomitant changes of the surface microstructure result in a pronounced two-peak profile of the Barkhausen noise signal: an additional peak arising from the surface-treated layer suppresses the initial peak generated in the bulk material. To confirm and explain the results obtained for semi-hard steel ribbons in the first part of this work (Stupakov et al., 2020), the steels with opposite surface treatments (soft decarburized and hard milled layers of different thickness) have been measured by commonly used detection sensors: classical sample-wrapping and industrial surface-mounted coils. To obtain physically accurate data, dynamic variations of the Barkhausen noise signal have been corrected using the recently proposed dH/dt normalization of its rms envelopes.