ARTICLE | doi:10.20944/preprints202112.0169.v1
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: Plumes; dynamics; resistivity; contamination; groundwater
Online: 10 December 2021 (11:28:20 CET)
The contamination of areas around solid urban waste dumps is a global challenge for the maintenance of environmental quality in large urban centres in developing countries. This study applied geophysical methods (electrical resistivity) to identify leachate contamina-tion plumes in the subsoil and groundwater, as well as to describe their temporal (2020 and 2021) dynamics in the lithology and groundwater around the Hulene - B waste dump, Maputo, Mozambique. Geophysical methods (electrical resistivity) were applied to identify possible groundwater contamination plumes, their dynamics, mechanisms of their enrichment and dispersion. Eight 400 m electrical resistivity profiles were performed, four profiles in January 2020 and four profiles in May 2021, overlapped, and the data were inverted with RES2D software. The electrical resistivity models indicate an E - W move-ment of large contamination plumes that dilute superficially into the natural surface wa-ter receiving basin and groundwater, creating zones of resistive anomalies. The thickness of the plumes in the subsurface environment was shown to be extensive in summer for profiles 1a and 2b and we associate it with the higher leachate production and migration mechanisms, which are intense in the hot and rainy season. Profile 4b showed the prop-agation of anomalous surface and subsurface areas, which was associated with higher leachate production and migration process in the new deposition zone (west). The spatial distribution of contamination plumes at both stations reduced significantly as we moved further away from the waste deposit, revealing the attenuating effect of groundwater and lithological substrate (Profile 3 a, b, and fig.7).
ARTICLE | doi:10.20944/preprints202305.1122.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: graphene oxide; carboxymethylcellulose; membrane; nanocomposite; resistivity
Online: 16 May 2023 (07:55:44 CEST)
In nowadays, the synthesis of new composite nanomaterials based on graphene oxide (GO) modified with cellulose and its derivatives, as well as nanocellulose, is an important direction and contributes to solve many problems in various fields such as: nanotechnology, information technology, medicine, high-dielectric materials and nanoelectronics. In this work, for the first time, for the production of GO and its membrane with carboxymethylcellulose (CMC), local Kazakhstan “Ognevsky” graphite was used as the initial raw material. In this regard, the preparation of nanocomposites of GO modified with cellulose derivatives, including CMC, attracts great interest from scientists and expands its field of practical application due to the amazing changes of physicochemical properties. In the work, the GO obtained by the Hummers method was modified by CMC, with following study of its physicochemical, structural and electrical characteristics. The GO/CMC membrane was synthesized by mixing 1% GO with crushed solid mass of CMC (0.03 g; 0.06 g; 0.15 g) and then was processed by ultrasound. The surface morphology of the GO/CMC membrane were studied using Scanning electron microscopy (SEM). It has been established that with an increasing in the mass of CMC (0.03 g; 0.06 g; 0.15 g), polymerization of CMC occurs on the surface of GO nanosheets. Cross-sectional micrographs of GO/CMC show the formation of sandwich-like layered structures.
ARTICLE | doi:10.20944/preprints202010.0360.v1
Subject: Physical Sciences, Acoustics Keywords: perovskite; manganite; resistivity; strain; grains; tilt angle
Online: 19 October 2020 (08:09:37 CEST)
The effects of an external strain tensor on the electrical resistivity of a manganite granular system are investigated using a simple approach describing the induced deformation in terms of the tilt angle between adjacent grains. The results obtained assuming the resistivity of each grain as given by a metallic part, coming from the inner grain, and a surface related tunnel contribution, allow to estimate appreciable resistivity variations even in the case of small deformation angles.
ARTICLE | doi:10.20944/preprints202307.0920.v1
Subject: Chemistry And Materials Science, Metals, Alloys And Metallurgy Keywords: Multi-pass; pulling annealing; tensile strength; elongation; resistivity
Online: 14 July 2023 (02:18:10 CEST)
The effects of various drawing parameters and annealing processes on the structure and properties of Cu-Ag wires, containing 1 wt% silver, were investigated using specialized equipment including fine wire drawing machines, very fine wire drawing machines, heat treatment equipment, tensile testing machines, microcomputer-controlled electronic universal testers, resistance testers, and scanning electron microscopes. The results revealed that continuous drawing of Cu-1%Ag alloy wires led to elongation of the grains, resulting in a uniform and tightly fibrous microstructure. Moreover, the tensile strength of the alloy wire increased from 670 MPa to 783.9 MPa after a single-pass with a deformation of 14%. Subsequently, when the wire was drawn at a speed of 500 m/min, the tensile strength further increased to 820.1 MPa. After annealing the Փ0.08 mm Cu-1% Ag alloy wire, an increase in annealing temperature up to 500°C resulted in the wire's tensile strength decreasing from 820.1 MPa to 377.5 MPa. Simultaneously, the elongation increased from 1.94% to 15.21%, and the resistivity decreased from 1.931×10-8Ω·m to 1.723×10-8Ω·m. Additionally, when annealing was conducted at a rate of 80 m/min, the wire resistivity dropped to 1.635×10-8Ω·m.
ARTICLE | doi:10.20944/preprints202307.0821.v1
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: Aquifer, electrical resistivity tomography, groundwater, Galgaduud region, Somalia.
Online: 13 July 2023 (05:21:52 CEST)
Electrical Resistivity Tomography (ERT) was conducted to delineate groundwater potential zones in villages located in the Galhareri district of the Galgaduud region, central Somalia. A total of four ERT profiles were examined using the gradient configuration, chosen for its practical advantages over other configurations. The study revealed that all profiles were situated within similar geological environments, characterized by comparable rock types. However, notable disparities were observed in lithological variations, particularly in the texture of rocks encountered at different locations and in the thicknesses of the encountered geo-electric layers. The two-dimensional inversion results derived from the electrical resistivity data unveiled the presence of four geo-electrical layers. The first layer was interpreted as sand dunes. The second layer exhibited relatively higher resistivity values, indicating the presence of compact limestone and sandstone. The resistivity of the third layer suggested the existence of a lower resistivity layer, interpreted as weathered limestone, while the fourth layer demonstrated very low apparent resistivity, interpreted as sandy clay with sandstone. The ERT models constructed for the survey area effectively delineated the aquifer zone, represented by layer 3, which likely consists of weathered limestone, sandy clay, and sandstone. The resistivity values obtained for the aquifer zone, specifically at depths ranging from 200 to 300 m, were relatively low, suggesting that the groundwater quality is brackish in nature
ARTICLE | doi:10.20944/preprints202108.0567.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: Silicone Rubber; Surface Resistance; Surface Resistivity; Surface Charging
Online: 31 August 2021 (11:29:32 CEST)
Silicone rubber formulations in the form of thin discs have been studied under room ambient conditions for their surface characteristics. The samples were silicone rubber manufactured in laboratory and those industrially manufactured. The measurements were done using an electrometer high resistance meter, applying dc voltage under normal room ambient conditions. The results show that the silicone rubber samples show higher values of surface resistivity when the dc voltage was applied. Silicone rubber samples manufactured in laboratory seem to exhibit erratic behaviour unlike their corresponding silicone rubbers manufactured in industry; this could be due to manufacturing shortcomings in laboratory and the irregularities in the way the silicone rubber adhered to the concentric ring electrodes. The empirical current traversing the surface of the silicone rubbers does not decay exponentially but rather it decays as an exponential power of the energization time.
ARTICLE | doi:10.20944/preprints202311.1736.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: nickel microparticles; polypyrrole; hybrid composites; resistivity; conductivity; magnetization; magnetorheology
Online: 28 November 2023 (03:39:07 CET)
Hybrid organic/inorganic conducting and magnetic composites of core–shell type have been prepared by in-situ coating of nickel microparticles with polypyrrole. Three series of syntheses have been made. In the first, pyrrole was oxidized with ammonium peroxydisulfate in water in the presence of various amounts of nickel and the composites contained up to 83 wt% of this metal. The similar syntheses in 0.1 M sulfuric acid followed. Finally, the composites with polypyrrole nanotubes were prepared in water in the presence of structure-guiding methyl orange dye. FTIR and Raman spectroscopies confirmed the formation of polypyrrole. The resistivity of composite powders of the order of tens to hundreds Ω cm was monitored as a function of pressure up to 10 MPa. The resistivity of composites slightly increased with increasing content of conducting nickel. This apparent paradox is explained by the coating of nickel particles, which prevents their contacts and generation of metallic conducting pathways. Electrical properties were practically independent of the way of composite preparation or nickel fraction and were controlled by polypyrrole phase. On the contrary, magnetic properties were determined exclusively by nickel content. The composites were used as a solid phase to prepare a magnetorheological fluid. The test showed better performance when compared with a different nickel system.
ARTICLE | doi:10.20944/preprints202309.0568.v1
Subject: Engineering, Civil Engineering Keywords: hydraulic conductivity; well logging; formation factor; fluid conductivity; resistivity
Online: 8 September 2023 (04:10:08 CEST)
The development of cost-effective methods for estimating hydraulic conductivity profiles has been an ongoing effort in the field of engineering practice, which can be used to increase availability to clarify the hydrogeological complexity of fractured rock aquifers for the aid of solving groundwater-related problems. A methodology is presented, which combines electrical well logs, fluid conductivity logs, double packer hydraulic tests, Archie’s law, and the Kozeny-Carman-Bear equation to investigate relations between formation factor and hydraulic conductivity. This method was applied to develop hydraulic conductivity profiles based on the data collected from 88 boreholes in Taiwan's mountainous areas. The investigation results include: (1) Well logging signals were suggested to be categorized by rock types to establish effective relationships with hydraulic conductivity. (2) Removing the mud-bearing section data with two proposed data clustering techniques could effectively enhance the correlation between the formation factor and hydraulic conductivity. (3) The predictive models for estimating hydraulic conductivity have been developed for sandstone, schist, and slate. (4) The prevalence of clay content in most of Taiwan's mountainous rock formations has been found, which implies that careful consideration of clay-related issues in complex geologic formations is essential while applying Archie's law theory.
ARTICLE | doi:10.20944/preprints202105.0669.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: porosity prediction; pore-water prediction; gravity; resistivity; combined inversion
Online: 27 May 2021 (13:16:28 CEST)
This work describes a method to carry out 2-D inversion of gravity data in terms of porosity and matrix density distribution using previous DC resistivity inversion results to constraint the fractional pore-water content in the rocks. The inversion is carried out using a controlled random search (CRS) algorithm for global optimization. The method was tested on synthetic data generated from a model representing a graben, and the results show that it can estimate accurate values of contrast-density and porosity. The method was also applied to gravity and dc experimental data collected in NE Portugal, showing results that agree quite well with the known geological information.
Subject: Engineering, Civil Engineering Keywords: chloride penetration; pore water; electrical resistivity; service life; concrete durability
Online: 18 March 2019 (09:11:10 CET)
Since electrical resistivity of concrete can be measured in a more rapid and simple way than chloride diffusivity, it should be primarily regular quality control of the electrical resistivity of concrete which provides the basis for indirect of quality control of concrete durability during the concrete construction. If this is realized, the electrical resistivity of concrete can be a crucial parameter to establish maintenance strategy for marine concrete structures. Electrical resistivity of concrete is important to estimate two processes involved in corrosion of reinforcement: initiation (chloride penetration) and propagation (corrosion rate). The resistivity of concrete structure exposed to chloride indicates the risk of early corrosion damage, because a low resistivity is related to rapid chloride penetration and to high corrosion rate. Concrete resistivity is a geometry-independent material property that describes the electrical resistance, which is the ratio between applied voltage and resulting current in a unit cell. The current is carried by ions dissolved in the pore liquid. While some data exist on the relationship between moisture content on electrical resistivity of concrete, very little research has been conducted to evaluate the effect of chloride on the conduction of electricity through concrete. The purpose of this study is to examine and quantify the effect of pore water and chloride content on surface electrical resistivity measurement of concrete. It was obvious that chloride content had influenced the resistivity of concrete and the relationship showed a linear function. That is, concrete with chloride ions had a comparatively lower resistivity. Chloride can lead to underestimate the electrical resistivity of concrete. Conclusively, this paper suggested the quantitative solution to depict the electrical resistivity of concrete with various chloride contents.
ARTICLE | doi:10.20944/preprints201909.0202.v1
Subject: Engineering, Energy And Fuel Technology Keywords: Plants-Microbial Fuel Cells; clean energy; electric potential; power output; resistivity
Online: 18 September 2019 (08:21:05 CEST)
Plants Microbial Fuel Cells (PMFC) is a new technology that generates electricity in a renewable, clean and sustainable way. In spite of these advantages, it still faces limitations in power generation and current density, reaching lower production values than other renewable technologies. Different studies maintain that the high resistivity of the cathode is the main limitation in the generation of energy; therefore, non-metallic materials to obtain a better performance are replacing the metallic electrodes. The implementation of these materials applied to PMFC requires a complex interdisciplinary work. Through three experimental tests using metallic electrodes for the extraction of electrons, this research study shows that the treatment of the substrate with natural materials, the volume plant roots, and substrate temperature and humidity control have a significant influence in the increase of the electric potential and the generated current.
COMMUNICATION | doi:10.20944/preprints202008.0011.v1
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: electrical resistivity tomography (ERT) method; polymer; carbomer; ground-electrode electrical contact enhancement; archaeology
Online: 2 August 2020 (10:58:15 CEST)
This communication reports an improvement of the quality of the electrical data obtained from the application of electrical resistivity tomography method on archaeological studies. The electrical contact between ground and electrode enhances significantly by using carbomer-based gel during the electrical resistivity tomography measurements. Not only does the gel promote the conservation of the building surface under investigation, but it also virtually eliminates the necessity of conventional spike electrodes, which in many archaeological studies are inadequate or not permitted. Results evidenced an enhancement in the quality of the electrical data obtained in the order of thousands of units compared with those without using the carbomer-based gel. The potential and capabilities of this affordable gel make it appropriate to be applied to other geoelectrical studies beyond archaeological investigations. Moreover, it might solve corrosion issues on conventional spike electrodes, and electrical multicore cables usually provoked for added saltwater attempting to improve the electrical contact.
ARTICLE | doi:10.20944/preprints202311.1443.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: ultra-high performance concrete； tensile-stress sensing；electrical resistivity；fractional resistance change； carbonation temperature
Online: 22 November 2023 (16:48:06 CET)
Although Sugarcane bagasse ash (SCBA) has good cementitious property, previous researchers have primarily aimed to improve the mechanical performance of conventional concrete or cement-based composites. Research is lacking on ultra-high performance concrete (UHPC), especially regarding tensile self-sensing properties. This paper aimed to comprehensively evaluate the SCBA effect on the UHPC’s mechanical, electrical, and tensile self-sensing properties. The results showed that SCBA below the critical incorporation concentration (CIC) improved the UHPC’s mechanical properties compared to steel fibers alone. Furthermore, adding 3.0wt% SCBA remarkably enhanced the UHPC mechanical properties where the compressive, flexural, and tensile strengths increased by 13.1%, 17.4%, and 20.6%, respectively. The SCBA content of 0.3wt% achieved the maximum UHPC electrical resistivity since values smaller or greater than this content decreased the resistivity. The SCBA-enhanced UHPC showed better tensile stress-sensing performance than UHPC without SCBA due to improved linearity and reversibility, lower hysteresis, higher sensitivity, and superior repeatability. UHPC with 0.3wt% SCBA achieved the best linearity, while UHPC with 0.9wt% SCBA showed the highest sensitivity, lowest hysteresis, and best repeatability. Overall, the content of 0.9wt% SCBA is the best in improving the overall mechanical, electrical, and tensile self-sensing performance.
ARTICLE | doi:10.20944/preprints202307.0532.v1
Subject: Physical Sciences, Condensed Matter Physics Keywords: ferromagnetic fluctuation; Tl-2201 cuprate; La-214 cuprate; Bi-2201 cuprate; electrical resistivity; magnetization
Online: 10 July 2023 (04:10:37 CEST)
To investigate proposed ferromagnetic fluctuations in the single-layer Bi-2201 and La-214 high-Tc cuprates, we performed magnetization and electrical-resistivity measurements using single-layer Tl-2201 cuprates Tl2Ba2CuO6+d as well as La-214 La2-xSrxCuO4 in the heavily overdoped regime. Magnetization of Tl-2201 exhibited the tendency to be saturated in high magnetic fields at low temperatures, suggesting the precursor behavior toward the formation of a ferromagnetic order. It was found that the power of temperature n obtained from the temperature dependence of the electrical resistivity is ~ 4/3 and ~5/3 for Bi-2201 and La-214, respectively, and is ~ 4/3 at high temperatures and ~5/3 at low temperatures in Tl-2201. These results suggest that two-dimensional ferromagnetic fluctuations exist in Tl-2201 at high temperatures and Bi-2201 and that three-dimensional ferromagnetic fluctuations exist in Tl-2201 at low temperatures and La-214. The dimensionality of ferromagnetic fluctuations is understood in terms of the dimensionality of the crystal structure and the bonding of atoms in the blocking layer.
Subject: Environmental And Earth Sciences, Geochemistry And Petrology Keywords: Tight sandstone; Low resistivity contrast oil pay; Reservoir Characteristic; Control mechanism; Longdong West area.
Online: 15 January 2021 (13:02:42 CET)
The log interpretation and evaluation of Chang 8 tight sandstone reservoir in Longdong West area, Ordos Basin, is facing great challenges due to the existence of low resistivity contrast oil pays. To better guide the exploration of oil resources in this area, the characteristics and control mechanism of low resistivity contrast oil pays were studied in this research. Firstly, according to the relative value of apparent resistivity increase rate of the target formation, the reservoir was divided into two types: low resistivity contrast oil pay (LRCP) and high resistivity oil pay (HRP). Then, the reservoir characteristics were studied by comparing and analyzing the experimental data, formation water data and logging data collected from the two reservoir types. On this basis, the control mechanism of LRCP was studied and summarized into reservoir micro factors and regional macro factors, respectively. It is found that the reservoir rock composition between LRCP and HRP is basically the same. Compared with HRP reservoir, the average porosity and permeability of LRCP reservoir are relatively better, but the pore structure is relatively poorer because of the high content of micro pores. When the filling pressure of crude oil is sufficient enough, the high oil saturation can be formed in LRCP reservoir. The high irreducible water saturation and high formation water salinity are the main micro factors reduced the reservoir resistivity. Besides, the difference of hydrocarbon expulsion capacity of source rock and the regional difference of formation water salinity are the macro factors influenced the distribution of LRCP and HRP from vertical and horizontal of the region. The formation of LRCP is controlled by the comprehensive influence of reservoir micro factors and regional macro factors. And the comprehensive consideration of the influence of micro factors and macro factors on LRCP is suggested during the log interpretation and evaluation.
ARTICLE | doi:10.20944/preprints202001.0269.v1
Subject: Chemistry And Materials Science, Metals, Alloys And Metallurgy Keywords: Niobium-titanium microalloyed steel; Electrical resistivity; Atom probe tomography; Solute niobium; Scanning transmission electron microscopy
Online: 23 January 2020 (16:15:44 CET)
Microalloying of low carbon steel with niobium (Nb) and titanium (Ti) is standardly applied in high-strength low-alloy (HSLA) steels enabling austenite conditioning during thermo-mechanical controlled processing (TMCP), which results in pronounced grain refinement in the finished steel. The metallurgical effects of microalloying elements are related solute drag and precipitate particle pinning, both acting on the austenite grain boundary thereby delaying or suppressing recrystallization of the deformed grain. In that respect it is important to better understand the precipitation kinetics as well as the precipitation sequence in a typical Nb-Ti-microalloyed steel. Various characterization methods have been utilized in this study for tracing microalloy precipitation after simulating different austenite TMCP conditions in a Gleeble apparatus. Atom probe tomography (APT), scanning transmission electron microscopy in a focused ion beam equipped scanning electron microscope (STEM-on-FIB) and electrical resistivity measurements provide complementary information on the precipitation status and are correlated with each other. It will be demonstrated that accurate electrical resistivity measurements can monitor the general consumption of solute microalloys (Nb) during hot working which was complemented by APT measurements of the steel matrix. On the other hand, STEM revealed that a large part of Nb-containing particles during hot working are co-precipitated with titanium during cooling from the austenitizing temperature. Precipitates that form during cooling or isothermal holding can be distinguished from strain-induced precipitates by corroborating STEM measurements with APT results. APT specifically allows obtaining detailed information about the chemical composition of precipitates as well as the distribution of elements inside the particle. Electrical resistivity measurement, on the contrary, provides macroscopic information on the progress of precipitation and can be calibrated by APT. The current paper highlights the complementarity of these methods and shows first results within the framework of a larger study on strain-induced precipitation.
ARTICLE | doi:10.20944/preprints201712.0124.v1
Subject: Chemistry And Materials Science, Electronic, Optical And Magnetic Materials Keywords: BiS2-based superconductor; Flux growth; Layered structure; Superconducting Properties; Magnetic susceptibility measurement; Electrical resistivity measurement
Online: 18 December 2017 (13:38:47 CET)
Antimony (Sb) Substitution less than 10 % is examined on a single crystal of a layered superconductor NdO0.7F0.3BiS2. Superconducting transition temperature of the substituted samples decreases with increasing Sb concentration. A lattice constant along the c axis showed a large decrease compared with that along the a axis. Since in-plane chemical pressure monotonically decreases with increasing Sb concentration, the suppression of the superconductivity is well described in terms of the decrease in in-plane chemical pressure.
ARTICLE | doi:10.20944/preprints202309.0810.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: bicontinuous composites; carbonized leather waste; conducting polymer; globular polypyrrole; polypyrrole nanotubes; conductivity; resistivity; dye adsorption; Raman spectra
Online: 13 September 2023 (16:17:08 CEST)
Leather waste was carbonized at 800 °C in inert atmosphere. The resulting biochar was coated in situ with polypyrrole nanotubes produced by the oxidation of pyrrole in the presence of methyl orange. The composites of carbonized leather with deposited polypyrrole nanotubes of various composition were compared with similar composites based on globular polypyrrole. Their molecular structure was characterized by infrared and Raman spectra. Both conducting components formed a bicontinuous structure. The resistivity determined by four-point van der Pauw method was monitored as a function of pressure applied up to 10 MPa. The typical conductivity of composites was of the order of tenths to units S cm−1 and it was always higher for polypyrrole nanotubes than for globular polypyrrole. The conductivity decreased by 1–2 orders of magnitude after treatment with ammonia but still maintained a level acceptable for applications operating under non-acidic conditions. The composites were tested for dye adsorption, viz. cationic methylene blue and anionic methyl orange, using UV-spectroscopy. The composites are designed for the future use as functional adsorbents controlled by the electrical potential.
ARTICLE | doi:10.20944/preprints202307.0170.v1
Subject: Engineering, Civil Engineering Keywords: Electrical resistivity; Half-cell potential; Impact echo; Machine learning; Multi-NDE; Corrosion; Bridge deck; concrete; Random Forest
Online: 4 July 2023 (10:23:23 CEST)
This research aimed to improve the interpretation of electrical resistivity (ER) results in concrete bridge decks by utilizing results from multiple nondestructive evaluations (NDE) techniques in machine learning algorithms. To achieve this, a parametric study was first conducted using numerical simulations to investigate the effect of various parameters on ER measurements, such as the degree of saturation, corrosion length, delamination depth, concrete cover, and the moisture condition of delamination. A data set from this study was used to build a machine-learning algorithm based on the Random Forest methodology. This algorithm was then implemented on data collected from a bridge deck in the BEAST® facility. The presented results demonstrate an improvement in the interpretation of ER measurements using data from other NDE technologies.
ARTICLE | doi:10.20944/preprints202305.0016.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: lead chalcogenides; thin-film thermoelectric converters; inorganic synthesis; Seebeck coefficient; resistivity; thermoelectric figure of merit; power factor
Online: 1 May 2023 (04:26:00 CEST)
Lead-based ternary chalcogenide thin films of the (PbTe)1-x(PbS)x system were obtained by plasma-enhanced chemical vapor deposition technique (PECVD) under conditions of a nonequilibrium low-temperature argon plasma of an RF discharge (40.68 MHz) at a reduced pressure (0.01 Torr). High-purity elements were directly used as starting materials – Pb, S and Te. Plasma-chemical synthesis was carried out on the surface of of c-sapphire and silicon substrate. The physicochemical properties of the films were studied by various analytical methods. The dependence of the Seebeck coefficient, resistivity, and power factor on the structural properties and composition has been studied. The thermoelectric characteristics were found to be dependent on the film composition. Upon the selection of optimal sulfur concentration one can increase the power factor as compared to single phase PbS ot PbTe films.
ARTICLE | doi:10.20944/preprints202106.0503.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: permafrost hydrology; Russian Arctic; water tracks; hydrological connectivity; stable water isotopes; dissolved organic carbon; electrical resistivity tomography; taliks
Online: 21 June 2021 (11:15:37 CEST)
Hydrochemical and geophysical data collected during a hydrological survey in September 2017, reveal patterns of small-scale hydrological connectivity in a small water track catchment, north-European Arctic. Elevated tundra patches underlain by sands were disconnected from the stream and stored precipitation water from previous months. At the catchment surface and in the water track thalweg, some circular hollows, from 0.2 to 0.4 m in diameter, acted as evaporative basins with low d-excess values, from 2 to 4‰. Other hollows were connected to shallow subsurface runoff, yielding d-excess values between 12 and 14‰. ‘Connected’ hollows yielded a 50% higher dissolved organic carbon (DOC) content, 17.5±5.3 mg/L, than the ‘disconnected hollows, 11.8±1.7 mg/L. Permafrost distribution across the landscape is continuous, but highly variable. Open taliks exist under fens and small hummocky depressions, as revealed by electric resistivity tomography surveys. Isotopic evidence supports upward subpermafrost groundwater migration through open taliks under water tracks and fens/bogs/depressions, and its supply to streams via shallow sub-surface compartment. Temporal variability of isotopic composition and DOC in water track and a major river system, the Vorkuta R., evidence the widespread occurrence of the described processes in the large river basin. Water tracks effectively drain the tundra terrain and maintain xeric veg-etation over the elevated inter-track tundra patches.
ARTICLE | doi:10.20944/preprints201905.0022.v1
Subject: Chemistry And Materials Science, Surfaces, Coatings And Films Keywords: sol-gel; Al-doped ZnO; hydrolysis; thin film; transparent conductors; resistivity; UV-Vis-NIR spectroscopy; figure of merit
Online: 5 May 2019 (12:49:18 CEST)
The electrical and optical properties of sol-gel derived aluminum-doped0 zinc oxide thin films containing 2 at.% Al were investigated considering the modifying effects of 1) increasing the sol H2O content; and 2) thermal treatment procedure with high-temperature approach followed by an additional heat-treatment step under a reducing atmosphere. According to the results obtained via the TG-DTA analysis, FT-IR spectroscopy, X-ray diffraction technique and four-point probe resistivity measurement, it is argued that the sol hydrolysis, decomposition of the deposited gel and crystallization of grains result in grains of larger crystallite size and stronger c-axis preferred orientation with slightly less microstrain in the modified sample. The consequent morphology and grain-boundary characteristics turn out as improved conductivity, implying higher values of concentration and mobility of charge carriers. A detailed investigation on samples optical properties, in terms of analyzing their absorption and dispersion behaviors through the UV-Vis-NIR spectroscopy, support our reasoning for the increase of the mobility, and to a lesser extent, the concentration of charge carriers, while causing only a slight degradation of optical transmission. Hence, an enhanced performance as a transparent conducting film is claimed for the modified sample by comparing the figure-of-merit values.
ARTICLE | doi:10.20944/preprints202310.1418.v1
Subject: Engineering, Civil Engineering Keywords: Half-cell potential; Electrical resistivity; Impact echo; Numerical simulation; Machine learning; Multi-NDE; Corrosion; Bridge deck; concrete; Random Forest; classification algorithm; regression algorithm
Online: 23 October 2023 (08:59:09 CEST)
Several factors impact the durability of concrete bridge decks, including traffic loads, fatigue, temperature changes, environmental stress, and maintenance activities. Detecting problems such as corrosion, delamination, or concrete degradation early on can lower maintenance costs. Nondestructive evaluation (NDE) techniques can detect these issues at early stages. Each NDE method, meanwhile, has limitations that reduce the accuracy of the assessment. In this study, multiple NDE technologies were combined with machine learning algorithms to improve the interpretation of half-cell potential (HCP) and electrical resistivity (ER) measurements. A parametric study was performed to analyze the influence of five parameters on HCP and ER measurements, such as degree of saturation, corrosion length, delamination depth, concrete cover, and moisture condition of delamination. The results were obtained through finite element simulations and used to build two machine learning algorithms, a classification algorithm and a regression algorithm, based on the Random Forest methodology. The algorithms were tested using data collected from a bridge deck in the BEAST® facility. Both machine learning algorithms were effective in improving the interpretation of ER and HCP measurements using data from multiple NDE technologies.
ARTICLE | doi:10.20944/preprints202112.0072.v1
Subject: Physical Sciences, Condensed Matter Physics Keywords: Integer quantum Hall effect; Fractional quantum Hall effect; stationary wave; nodes in stationary wave; quantization of electric charge; the plateau of quantized resistivity
Online: 6 December 2021 (12:49:01 CET)
In this paper, using the two integers that describe the stationary 2-dimensional wave and the charge quantization along with the balance between the Lorentz force and electrical force, we succeed in deriving the fractional quantum Hall effect and the integer quantum Hall effect; we find that the latter exists as a special case of the former. Moreover, using the derived expression describing the fractional quantum Hall effect, a relationship between the plateau in the resistivity of the sample and the applied magnetic field is obtained. The findings of this model agree well with experimental measurements. Because the two integers that describe the stationary 2-dimensional wave and the charge quantization along with the force balance have concrete physical meanings in this work, we could provide a clear picture of the origin of both the integer quantum Hall effect and the fractional quantum Hall effect.