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Showing records 901 to 925 of 4494. [First] Page: 33 34 35 36 37 38 39 40 41 Last
Mass Spectrometric Calibration Procedure for Real-Time Detection of Lighter Hydrocarbons
Makuachukwu F. Mbaegbu, Puspa L. Adhikari, Ipsita Gupta, Mathew Rowe
April 19, 2023 (v1)
Subject: Materials
Keywords: base peaks, fragmentation, lighter hydrocarbons, mass spectrometric calibration
Determining gas compositions from live well fluids on a drilling rig is critical for real time formation evaluation. Development and utilization of a reliable mass spectrometric method to accurately characterize these live well fluids are always challenging due to lack of a robust and effectively selective instrument and procedure. The methods currently utilized need better calibration for the characterization of light hydrocarbons (C1−C6) at lower concentrations. The primary goal of this research is to develop and optimize a powerful and reliable analytical method to characterize live well fluid using a quadruple mass spectrometer (MS). The mass spectrometers currently being used in the field have issues with detection, spectra deconvolution, and quantification of analytes at lower concentrations (10−500 ppm), particularly for the lighter (<30 m/z) hydrocarbons. The objectives of the present study are thus to identify the detection issues, develop and optimize a better method, cali... [more]
Preparation and Characterization of Core-Shell Structure Hard Carbon/Si-Carbon Composites with Multiple Shell Structures as Anode Materials for Lithium-Ion Batteries
Jong-Chan Kim, Kyung-Jin Kim, Sung-Man Lee
April 19, 2023 (v1)
Subject: Materials
Keywords: anode material, core-shell composites, hard carbon, Li-ion battery, Si-carbon composites
Novel core-shell structure hard carbon/Si-carbon composites are prepared, and their electrochemical performances as an anode material for lithium-ion batteries are reported. Three different types of shell coating are applied using Si-carbon, Si-carbon black-carbon and Si-carbon black-carbon/graphite nanosheets. It appears that the use of n-Si/carbon black/carbon composite particles in place of n-Si for the shell coating is of great importance to achieve enhanced electrochemical performances from the core-shell composite samples, and additional wrapping with graphite nanosheets leads to a more stable cycle performance of the core-shell composites.
A Flexible Piezoelectric Energy Harvester-Based Single-Layer WS2 Nanometer 2D Material for Self-Powered Sensors
Quan Wang, Kyung-Bum Kim, Sang Bum Woo, Yoo Seob Song, Tae Hyun Sung
April 19, 2023 (v1)
Subject: Materials
Keywords: flexible device, human movement, monolayer, piezoelectric energy harvester, tungsten disulfide
A piezoelectric sensor is a typical self-powered sensor. With the advantages of a high sensitivity, high frequency band, high signal-to-noise ratio, simple structure, light weight, and reliable operation, it has gradually been applied to the field of smart wearable devices. Here, we first report a flexible piezoelectric sensor (FPS) based on tungsten disulfide (WS2) monolayers that generate electricity when subjected to human movement. The generator maximum voltage was 2.26 V, and the produced energy was 55.45 μJ of the electrical charge on the capacitor (capacity: 220 μF) when applying periodic pressing by 13 kg. The generator demonstrated here can meet the requirements of human motion energy because it generates an average voltage of 7.74 V (a knee), 8.7 V (a sole), and 4.58 V (an elbow) when used on a running human (weight: 75 kg). Output voltages embody distinct patterns for different human parts, the movement-recognition capability of the cellphone application. This generator is q... [more]
Efficient Optical Limiting in Carbon-Nanohorn Suspensions
Elisa Sani, Nicolò Papi, Luca Mercatelli, Aldo Dell’Oro
April 19, 2023 (v1)
Subject: Materials
Keywords: bubble generation, carbon nanohorns, nanofluids, optical limiting, solar energy, vapor generation
Nonlinear optical properties of aqueous dispersions of single-wall carbon nanohorns (SWCNH) are investigated by a simple and original technique, relating nonlinear transmittance measurements with semi-empirical model fitting and allowing to identify the dominant nonlinear mechanism. The nanofluids shown a particularly strong optical limiting under irradiation by nanosecond laser pulses at 355, 532 and 1064 nm, much stronger than that previously reported in SWCNHs with smaller aggregate size. The effect is more relevant at 355 nm, where a nearly ideal optical limiting behavior with output energy practically independent on the input one is obtained, and it is attributed to the massive production of bubbles under the effect of light irradiation. This result opens interesting perspectives for the use of SWNCH-based suspensions for smart materials applications and green energy.
Electrochromic Properties of the Vanadium Pentoxide Doped with Nickel as an Ionic Storage Layer
Tien-Chai Lin, Bai-Jhong Jheng, Wen-Chang Huang
April 19, 2023 (v1)
Subject: Materials
Keywords: electrochromic, ionic storage layer, nickel, vanadium pentoxide
The electrochromic property of nickel doped vanadium pentoxide (V2O5) deposited by a co-sputtering system is investigated. The structural analysis of the thin film was done by an X-ray diffraction (XRD) analyzer. The surface morphology of the film was studied by a field emission scanning electron microscopy (FE-SEM). The composition of the film was detected by an Auger analysis. The electrochromic properties of the device were measured by cyclic voltammetry. For the undoped V2O5 thin film, the charge storage capacity increases with the thickness and is 42.58 mC/cm2 at the thickness of 192.4 nm after 2 h deposition. For the Ni-doped V2O5, the Ni-V-O film shows V2O5 structural dominate with cathode coloration in the lower Ni deposition power region and the charge storage capacity decreases with the increases of the power, while the Ni-V-O film transfers to NiO structural dominate with anodic coloration at the realm of higher Ni doping. The charge storage capacity increases with the incre... [more]
Principles of Sustainable Management of Energy Companies: The Case of Poland
Elżbieta Jędrych, Dariusz Klimek, Agnieszka Rzepka
April 19, 2023 (v1)
Subject: Materials
Keywords: efficiency, Energy, energy companies, management goals, sustainable management
In 2016, a law was introduced in Poland that required management bodies of energy companies owned by the state and a municipality to adopt management goals. The remuneration of the board members of these companies depended on the extent to which these goals were implemented. The challenge was that profit became an end in itself. The purpose of this article is to describe the process used to set up strategic goals on the basis of balancing capital within energy companies, which demonstrates a positive impact on the effectiveness of these companies. The solution proposed in this article is an alternative to using profit as the sole measure. The article consists of three parts. The first part is a review of the literature on management goals and how they relate to various economic measures—the main conclusions of this literature review were that, despite many attempts, we were not able to (1) clearly define the purpose of a company and (2) find an indisputable measure of the degree to whi... [more]
Low-Rank Coal Supported Ni Catalysts for CO2 Methanation
Soohyun Kim, Yunxia Yang, Renata Lippi, Hokyung Choi, Sangdo Kim, Donghyuk Chun, Hyuk Im, Sihyun Lee, Jiho Yoo
April 19, 2023 (v1)
Subject: Materials
Keywords: carbon support, ceria, CO2 methanation, low-rank coal, magnesia, nickel
As renewable energy source integration increases, P2G technology that can store surplus renewable power as methane is expected to expand. The development of a CO2 methanation catalyst, one of the core processes of the P2G concept, is being actively conducted. In this work, low-rank coal (LRC) was used as a catalyst support for CO2 methanation, as it can potentially enhance the diffusion and adsorption behavior by easily controlling the pore structure and composition. It can also improve the process efficiency owing to its simplicity (no pre-reduction step) and high thermal conductivity, compared to conventional metal oxide-supported catalysts. A screening of single metals (Ni, Co, Ru, Rh, and Pd) on LRC was performed, which showed that Ni was the most active. When Ni on the LRC catalyst was doped with a promoter (Ce and Mg), the CO2 conversion percentage increased by >10% compared to that of the single Ni catalyst. When the CO2 methanation activity was compared at 250−500 °C, the Ce-do... [more]
Experimental Procedures & First Results of an Innovative Solid Oxide Fuel Cell Test Rig: Parametric Analysis and Stability Test
Luca Del Zotto, Andrea Monforti Ferrario, Arda Hatunoglu, Alessandro Dell’Era, Stephen McPhail, Enrico Bocci
April 19, 2023 (v1)
Subject: Materials
Keywords: electrochemical characterization, fuel cell testing, SOFC, Solid Oxide Fuel Cells
Solid Oxide Fuel Cells are a promising technology for Solid Oxide Fuel Cells (SOFC) are a promising technology For high-efficiency electrochemical conversion of a vast range of fuel gas mixtures, thigh operating temperature conditions (650−900 °C) represent a challenge both at system level and at laboratory testing level, in terms of material properties and performance dynamics. In this work a detailed procedural analysis is presented for an innovative all-ceramic compact SOFC test rig and first experimental testing results are reported in terms of polarization curves obtained under parametric variation of operating conditions (H2 content, air ratio λ and temperature) and short-term voltage stability test under load (140 h at 0.3 A/cm2). The electrochemical characterization results confirm the validity of the used all-ceramic cell holder, showing excellent cell performances in terms of polarization. H2 content has the most impact on SOFC performance, followed by temperature and finally... [more]
Estimating of Non-Darcy Flow Coefficient in Artificial Porous Media
Abadelhalim Elsanoose, Ekhwaiter Abobaker, Faisal Khan, Mohammad Azizur Rahman, Amer Aborig, Stephen D. Butt
April 19, 2023 (v1)
Subject: Materials
Keywords: Forchheimer numbers, non-Darcy, non-Darcy coefficient, porous media
This study conducted a radial flow experiment to investigate the existence of non-Darcy flow and calculate the non-Darcy “inertia” coefficient; the experiment was performed on seven cylindrical perforated artificial porous media samples. Two hundred thirty-one runs were performed, and the pressure drop was reported. The non-Darcy coefficient β was calculated and compared with available in the literature. The results showed that the non-Darcy coefficient decreased nonlinearly and converged on a value within a specific range as the permeability increased. Nonetheless, it was found that the non-Darcy flow exists even in the very low flow rate deployed in this study. In addition, it has been found that the non-Darcy effect is not due to turbulence but also the inertial effect. The existence of a non-Darcy flow was confirmed for all the investigated samples. The Forchheimer numbers for airflow at varied flow rates are determined using experimentally measured superficial velocity, permeabili... [more]
The Effect of Adjusting Sinter Raw Mix on Dioxins from Iron Ore Co-Sintering with Municipal Solid Waste Incineration Fly Ash
Hao He, Xuanhao Guo, Lizheng Jin, Yaqi Peng, Minghui Tang, Shengyong Lu
April 19, 2023 (v1)
Subject: Materials
Keywords: inhibition, iron ore sintering, municipal solid waste incineration fly ash (MSWI FA), PCDD/Fs
The inhibition effect of calcined lime (CaO) and limestone (CaCO3) on the formation of dioxins during iron ore co-sintering with fly ash was investigated in a sinter pot in the present work. Experimental results indicated that international total toxicity equivalent concentration of dioxins decreased from 1.4335 to 0.2922, 0.1048, 0.4562, and 0.3098 ng I-TEQ Nm−3 under four different experimental conditions. It can be concluded that 5 wt.% calcined lime with 3 wt.% limestone is the optimal addition to reduce the concentration of dioxins in flue gas, with 92.70% inhibition efficiency. Effects on dioxin distribution was also analyzed. The distribution proportion of low-chlorinated dioxins was found to increase, while that of high-chlorinated dioxins decreased, except for octachlorianted dibenzo-p-dioxins (OCDD). The reason is that the consumption of HCl not only inhibits the de novo synthesis, but also dramatically promotes the condensation and dechlorination to produce more tetrachloria... [more]
Influence of Ester Liquids on Dielectric Strength of Cellulose Kraft Paper
Gottapu Tirupati Naidu, Ungarala Mohan Rao, Sudabattula Suresh
April 19, 2023 (v1)
Subject: Materials
Keywords: cellulose paper, dielectric strength, ester fluids, insulating oil
Generally, impregnation of solid insulation is performed to increase the dielectric strength and reduce the dielectric losses of solid insulants. This increase in dielectric strength depends on the oil’s diffusion and dielectric properties. This paper investigates the diffusion behavior of mineral oil and ester fluids (synthetic, natural, and mixed) to understand the influence of oil diffusion on paper breakdown voltage. To better understand this phenomenal influence, cellulose insulation paper of different thicknesses has been considered. Wetting characteristics of various oil-paper insulation systems were investigated with and without thermal stressing. Thermal aging was carried out as per modified ASTM D1934 at 110 °C, 140 °C, 160 °C, and 185 °C respectively for 2 weeks. The wetting characteristics and influence of different oils on paper breakdown voltage were explicitly reported. It is inferred that paper wetting characteristics are attributable to the type of oil, the thickness o... [more]
Residual Strength Assessment and Residual Life Prediction of Corroded Pipelines: A Decade Review
Haotian Li, Kun Huang, Qin Zeng, Chong Sun
April 19, 2023 (v1)
Subject: Materials
Keywords: evaluation criterion, intelligent model, residual life, residual strength
Prediction of residual strength and residual life of corrosion pipelines is the key to ensuring pipeline safety. Accurate assessment and prediction make it possible to prevent unnecessary accidents and casualties, and avoid the waste of resources caused by the large-scale replacement of pipelines. However, due to many factors affecting pipeline corrosion, it is difficult to achieve accurate predictions. This paper reviews the research on residual strength and residual life of pipelines in the past decade. Through careful reading, this paper compared several traditional evaluation methods horizontally, extracted 71 intelligent models, discussed the publishing time, the evaluation accuracy of traditional models, and the prediction accuracy of intelligent models, input variables, and output value. This paper’s main contributions and findings are as follows: (1) Comparing several traditional evaluation methods, PCORRC and DNV-RP-F101 perform well in evaluating low-strength pipelines, and D... [more]
Graphene Utilization for Efficient Energy Storage and Potential Applications: Challenges and Future Implementations
Umair Yaqub Qazi, Rahat Javaid
April 18, 2023 (v1)
Subject: Materials
Keywords: challenges, Energy Storage, graphene, graphene derivatives, potential applications
Allotropes of carbon are responsible for discovering the three significant carbon-based compounds, fullerene, carbon nanotubes, and graphene. Over the last few decades, groundbreaking graphene with the finest two-dimensional atomic structure has emerged as the driving force behind new research and development because of its remarkable mechanical, electrical, thermal, and optical functionalities with high surface area. Synthesis of graphene oxide (GO) and reduced graphene oxide (rGO) has resulted in numerous applications that previously had not been possible, incorporating sensing and adsorbent properties. Our study covers the most prevalent synthetic methods for making these graphene derivatives and how these methods impact the material’s main features. In particular, it emphasizes the application to water purification, CO2 capture, biomedical, potential energy storage, and conversion applications. Finally, we look at the future of sustainable utilization, its applications, and the cha... [more]
A Platform for Outdoor Real-Time Characterization of Photovoltaic Technologies
Sammy J. Martínez-Deusa, Carlos A. Gómez-García, Jaime Velasco-Medina
April 18, 2023 (v1)
Subject: Materials
Keywords: monitoring system, organic photovoltaic (OPV), outdoor performance, solar panel characterization, thin-film photovoltaic
In recent years, thin-film and organic photovoltaic (OPV) technologies have been increasingly used as alternatives to conventional technologies due to their low weight, portability, and ease of installation. Outdoor characterization studies allow knowing the real performances of these photovoltaic (PV) technologies in different environmental conditions. Therefore, to address the above, this article presents the hardware−software design and implementation of an integrated and scalable platform for performing the outdoor real-time characterization of modern PV/OPV technologies located at different altitudes. The platform allows knowing the outdoor performance of PV/OPV technologies in real environmental conditions by acquiring data from different monitoring stations located at different altitudes. The proposed platform allows characterizing solar panels and mini-modules and acquiring relevant information to analyze power generation capacity and efficiency. Furthermore, other devices for... [more]
Theoretical Investigation of Rate Rules for H-Intermigration Reactions for Cyclic Alkylperoxy Radicals
Kun Yang, Zemin Tian, Jinghua Li, Yingwen Yan
April 18, 2023 (v1)
Subject: Materials
Keywords: ab initio calculation, cycloalkylperoxy radicals, H-intermigration reaction, rate rules
As a starting channel, the H-intermigration reaction of alkylperoxy radicals (ROO radicals) that yields hydroperoxyl alkyl radicals (QOOH radicals) determines the low-temperature chemistry of alkanes. In this work, this type of reaction was investigated for typical cyclic alkanes, which are important fuel components and soot precursors, using theoretical ab initio methods. First, all the molecular geometries and vibrational frequencies were computed using the density functional theory method and the single point energies were refined using the post-Hartree fork method (M062X/6-311G(d,p)//DLPNO-CCSD(T)/CBS). Then, high-pressure limit rate constants were evaluated with tight transition state theory, with which tunneling effects were considered using the Eckart model and low-frequency torsion modes were modeled as hindered rotors. Pressure-dependent rate constants were also calculated for typical reaction channels. Rate expressions in the Arrhenius form for 91 reactions are proposed. All... [more]
Salt Hydrate Adsorption Material-Based Thermochemical Energy Storage for Space Heating Application: A Review
Hui Yang, Chengcheng Wang, Lige Tong, Shaowu Yin, Li Wang, Yulong Ding
April 18, 2023 (v1)
Subject: Materials
Keywords: adsorption/desorption performance, composite materials, host matrix, salt hydrate, thermochemical energy storage
Recent years have seen increasing attention to TCES technology owing to its potentially high energy density and suitability for long-duration storage with negligible loss, and it benefits the deployment of future net-zero energy systems. This paper provides a review of salt hydrate adsorption material-based TCES for space heating applications at ~150 °C. The incorporation of salt hydrates into a porous matrix to form composite materials provides the best avenue to overcome some challenges such as mass transport limitation and lower thermal conductivity. Therefore, a systematic classification of the host matrix is given, and the most promising host matrix, MIL-101(Cr)(MOFs), which is especially suitable for loading hygroscopic salt, is screened from the perspective of hydrothermal stability, mechanical strength, and water uptake. Higher salt content clogs pores and, conversely, reduces adsorption performance; thus, a balance between salt content and adsorption/desorption performance sho... [more]
Analysis of Forest Biomass Wood Briquette Structure According to Different Tests of Density
Kamil Roman, Witold Rzodkiewicz, Marek Hryniewicz
April 18, 2023 (v1)
Subject: Materials
Keywords: briquettes, forest residues, wooden chips, X-ray radiation
X-ray technology is capable of non-destructively testing solid wood samples. The prepared wood briquette samples were identified by X-ray technology. The studies assessed the effect of biomass briquette structure by observing wood chip fractions under an X-ray. Study results show that X-ray technology is an effective tool for analyzing biomass wood-based materials, e.g., density, improving wood products quality and performance. The measurements are consistent with the true density, and chemical properties were measured from chosen material. In the article, a coefficient representing the picture density and true density of briquettes was proposed, and the comparison of both densities was based on the empirical measurements. Probably through an application of the conversion factor, the process of determining material densities could be simplified, cheaper, and quicker. Due to the conducted research, X-ray technology is an effective tool for improving wood products’ quality and performanc... [more]
Biocementation as a Pro-Ecological Method of Stabilizing Construction Subsoil
Katarzyna Stefaniak, Jędrzej Wierzbicki, Barbara Ksit, Anna Szymczak-Graczyk
April 18, 2023 (v1)
Subject: Materials
Keywords: bio-cementation, MICP (microbially induced calcite precipitation), shear strength, Sporosarcina pasteurii, stabilization
The principle of sustainable development imposes an obligation on societies to manage natural resources rationally and to care for the quality of the environment, by, among other things, reducing CO2 emissions. Alternative ways of stabilising building substrates by increasing their shear strength (cu) are increasingly being sought. This paper presents how microorganisms can influence cu and thus the load-bearing capacity of building substrates. Tests were performed in a triaxial compression apparatus in three variants. The first variant of testing was carried out on cemented soil samples, which were cemented in situ. The next two series of tests were performed on reconstructed samples, i.e., natural soil and soil inoculated with a solution of Sporosarcina pasteurii bacteria. The results obtained show that carbonate cementation increases the shear strength of the soil; in addition, this biomineralization-induced cementation gives higher cu results than natural carbonate cementation.
Small-Scale Phase Change Materials in Low-Temperature Applications: A Review
Leland Weiss, Ramanshu Jha
April 18, 2023 (v1)
Subject: Materials
Keywords: form stability, heat sink, material additives, micro, nano, PCM, Sustainability, temperature control, thermal energy storage
Significant efforts have explored the field of Phase Change Materials (PCMs) for various applications. Research and real-world applications explore length scales that range from infrastructure to micro systems. A commonality of these efforts is the desire to utilize the phase change capability of the PCM to provide a steady temperature heat sink for thermal storage. Smaller scale efforts and materials are presented in this present review. A general challenge to the use of these PCMs regardless of application is the low thermal conductivity present as a baseline material property. Efforts to improve thermal conductivity have included the addition of underlying metal foam structures, heat pipes, or metallic fins inserted into the base PCM. Other efforts have investigated alterations to the base materials themselves by employing additives such as graphite to supplement thermal performance. Other additives are used to obtain form stability in the PCM as it melts. While the field of PCM res... [more]
Chemical and Microbiological Techniques for Recovery and/or Removal of Elements from Incinerated Sewage Sludge Ash—A Review of Basic Methods
Monika Kasina, Kinga Jarosz
April 18, 2023 (v1)
Subject: Materials
Keywords: bioleaching, chemical extraction, incineration sewage sludge ash, leaching, metals recovery
In the face of material shortages, growing environmental awareness, and technical advancement, incinerated waste materials are being considered secondary resources. Especially incinerated sewage sludge ash is of interest due to its massive and increasing production and relatively stable composition with a satisfying concentration of elements of value. This paper revises the basic methods for recovery of valuable components from incineration sewage sludge and simultaneous removal or stabilization of elements that may negatively influence the environment with further ash usage or storage. The presented work focuses on collating and analysing the efficiency of currently used approaches as well as their limitations and perspectives for future development. Chemical methods analysed include acidic and alkaline leaching, chelating, and sequential leaching. Due to scarce examples from literature, the exploration of a microbiological approach focuses on the mechanisms and potential for applicat... [more]
Practical Approximation of Sheet Losses Taking into Account the Guillotine and Laser Cutting Effect
Maria Dems, Krzysztof Komeza, Jacek Szulakowski
April 18, 2023 (v1)
Subject: Materials
Keywords: cutting effect, electrical steel sheet specific loss, loss approximation, losses in electrical machines
Reducing losses in electrical devices is essential for reducing global energy consumption. Losses in the core of electrical machines constitute a significant part of the overall losses—their share increases with the number of machines powered by PWM converters, especially for high-speed machines. Limiting core losses requires precise determination at the design stage of the device. Achieving this goal is possible thanks to numerical or analytical simulation. A necessary input for this process is the correct determination of the properties of the core material. The sheet loss, however, changes due to the machining process, primarily punching. The subject of the work is to develop a sufficiently accurate approximation of electrical steel sheet-specific loss, taking into account the effects of cutting and the width of a given machine element for a wide range of induction and frequency. The method also enables the extrapolation of losses for higher frequencies relevant from the point of vi... [more]
Experimental/Numerical Investigation and Prediction of Fouling in Multiphase Flow Heat Exchangers: A Review
Rached Ben-Mansour, Sami El-Ferik, Mustafa Al-Naser, Bilal A. Qureshi, Mohammed Ahmed Mohammed Eltoum, Ahmed Abuelyamen, Fouad Al-Sunni, Ridha Ben Mansour
April 18, 2023 (v1)
Subject: Materials
Keywords: desalination, fouling characterization, heat exchangers, Modelling, monitoring, phase change
Fouling build-up is one of the most challenging problems for heat exchangers in industry. The presence of fouling leads to a degradation of system efficiency, an increase in operating cost, and possibly, a harmful environmental impact. For this reason, fouling analysis has become an extremely important research subject in order to have a safe and efficient operation. The analysis is more difficult where phase change of fluids is involved during the heat transfer process, as in the case of boilers and condensers, which are critical units in industrial facilities. Due to the lack of a comprehensive review of fouling analysis for the case of multiphase heat exchangers, this paper examines available approaches and techniques used for fouling characterization, modeling, monitoring, and prediction in heat exchangers for both single-phase and multiphase heat exchangers with a focus on fouling in thermal desalination systems. It also gives an overview of heat exchanger condition monitoring sol... [more]
Catalytic Oxidation of Volatile Organic Compounds Using the Core−Shell Fe2O3-Cenospheric Catalyst in a Fluidised Bed Reactor
Przemysław Migas, Witold Żukowski, Dariusz Bradło
April 18, 2023 (v1)
Subject: Materials
Keywords: core–shell catalyst, fluidisation, incomplete oxidation products, VOC removal
The results of selected volatile organic compounds (benzene, n-hexane, isopropanol, and formic acid) catalytic oxidation are presented on Fe2O3 cenospheres in the fluidised bed reactor. The core−shell Fe2O3-cenosphere catalyst was developed by applying an Fe layer on cenospheres by FB-MO-CVD (fluidised bed, metal−organic chemical vapor deposition) and following Fe layer oxidation. The efficiency of the decomposition of VOCs was tested in the range of 200 to 500 °C, using the method based on infrared spectroscopy (FTIR). The research was focused especially on the analysis of incomplete combustion products, such as CO and oxygen compounds. During the oxidation of isopropanol and n-hexane, in addition to carbon monoxide, species such as acetone, formaldehyde, and acetaldehyde were also detected. The oxidation of formic acid proceeded with only a slight emission of carbon monoxide, unexpectedly the oxidation of benzene proceeded in a similar way, and no other products of the incomplete oxi... [more]
Finite Element Study of Electrical MHD Williamson Nanofluid Flow under the Effects of Frictional Heating in the View of Viscous Dissipation
Muhammad Shoaib Arif, Wasfi Shatanawi, Yasir Nawaz
April 18, 2023 (v1)
Subject: Materials
Keywords: finite element method, Matlab bvp4c, numerical integration, viscous dissipation, Williamson fluid
This study addresses heat and mass transfer of electrical magnetohydrodynamics (MHD) Williamson fluid flow over the moving sheet. The mathematical model for the considered flow phenomenon is expressed in a set of partial differential equations. Later, linear and nonlinear ordinary differential equations (ODEs) are obtained. The finite element method tackles a reduced system of ODEs with boundary conditions. Galerkin weighted residuals and constructs of weak formulations constitute the basis of this method. An iterative procedure is considered for handling nonlinear terms in a given system of ODEs. Some results acquired using the finite element method are compared with those reported in previous research via the Matlab solver bvp4c in order to validate the obtained solutions of ODEs. It is seen that the velocity profile is decayed by enhancing the Wiesenberg number. The finite element method also converges to an accurate solution by increasing the number of elements, whereas Matlab solv... [more]
Characterizing Complex Deformation, Damage, and Fracture in Heterogeneous Shale Using 3D-DIC
Fatick Nath, Gabriel Aguirre, Edgardo Aguirre
April 18, 2023 (v1)
Subject: Materials
Keywords: 3D-DIC, damage variables, deformation, diametrical compression, strain localization zone, uniaxial compression
Safe drilling and effective fracturing are constant challenges for shale formations. One of the most important influencing factors is the accurate characterization of the deformation and damage caused by inherent lamination and natural fractures. Furthermore, shale formations exhibit fine-scale heterogeneity, which conventional laboratory methods (linear variable differential transformer (LVDT), strain gauges, etc.) cannot distinguish. To overcome these constraints, this research aims to investigate the damage and deformation characteristics of shale samples using three-dimensional digital image correlation (3D-DIC). Under uniaxial and diametrical compression, samples of Wolfcamp, Mancos, and Eagle Ford shale with distinct lamination and natural fractures are evaluated. The 3D-DIC system is utilized for image processing, visualization, and analysis of the shale damage process under varying loads. DIC made quantitative full-field strain maps with load (tension, compression, and shear),... [more]
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