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Showing records 76 to 100 of 1263. [First] Page: 1 2 3 4 5 6 7 8 Last
Bio-Methane Production via Anaerobic Co-Digestion by Optimizing the Mixing Ratios of River Tamarind (Leucaena leucocephala) and Dolphin Fish (Coryphaena hippurus) Offal
Nikolai Holder, Marilaine Mota-Meira, Jens Born, Sarah L. Sutrina
December 17, 2020 (v1)
Keywords: anaerobic digestion, biogas, biomethane, co-digestion, fish offal, river tamarind
Fish offal and other high protein substrates are generally not suitable for anaerobic digestion because of the high levels of ammonia produced as a result of their biodegradation. In order to efficiently use these types of substrates to produce methane, co-digestion is used to balance the amounts of carbon and nitrogen in the feedstock. In this experiment an optimization procedure for maximizing the methane potential of fish offal, using river tamarind as the co-substrates was developed. Our experimental design tested the effects of substrate to substrate mixtures, as well as overall substrate to inoculum combinations, on the methane potentials. This was performed using batch style biochemical methane potential assays, which employed a methodology developed in our laboratory. The optimum of the 25 combinations tested was 50% fish offal to 50% river tamarind at a substrate to inoculum ratio of 0.03, with a specific methane yield of 144 ± 6 NmL/gFM (330 ± 14 NmL/goDM). This gave much imp... [more]
Electrical Resistivity of Carbonaceous Bed Material at High Temperature
Gerrit Ralf Surup, Tommy Andre Pedersen, Annah Chaldien, Johan Paul Beukes, Merete Tangstad
December 17, 2020 (v1)
Subject: Materials
Keywords: charcoal, Coal, coke, electrical resistivity, high-temperature treatment, pyrolysis
This study reports the effect of high-temperature treatment on the electrical properties of charcoal, coal, and coke. The electrical resistivity of industrial charcoal samples used as a reducing agent in electric arc furnaces was investigated as a renewable carbon source. A set-up to measure the electrical resistivity of bulk material at heat treatment temperatures up to 1700 ∘C was developed. Results were also evaluated at room temperature by a four-point probe set-up with adjustable load. It is shown that the electrical resistivity of charcoal decreases with increasing heat treatment temperature and approaches the resistivity of fossil carbon materials at temperatures greater than 1400 ∘C. The heat treatment temperature of carbon material is the main influencing parameter, whereas the measurement temperature and residence time showed only a minor effect on electrical resistivity. Bulk density of the carbon material and load on the burden have a large impact on the electrical resistiv... [more]
Using CFD Simulations to Guide the Development of a New Spray Dryer Design
Timothy A. G. Langrish, James Harrington, Xing Huang, Chao Zhong
December 17, 2020 (v1)
Keywords: chamber design, glass transition, spray drying, wall deposition
A new spray-drying system has been designed to overcome the limitations caused by existing designs. A key feature of the approach has been the systematic use of Computational Fluid Dynamics (CFD) to guide innovation in the design process. An example of an innovation is the development of a box-shaped transitional feature between the bottom of the main drying chamber and the entrance to the secondary chamber. In physical experiments, the box design performed better in all three representative operating conditions, including the current conditions, a higher feed solids concentration (30% solids rather than 8.8%), and a higher inlet drying temperature (230 °C rather than 170 °C). The current conditions showed a 3% increase in yield (solids recovery) while the 30% feed condition improved the yield by 7.5%, and the higher temperature test increased the yield by 13.5%. Statistical analysis showed that there were significant reductions in the wall flux at the high solids feed concentration. T... [more]
Treatment of Cheese Whey Wastewater Using an Expanded Granular Sludge Bed (EGSB) Bioreactor with Biomethane Production
Abumalé Cruz-Salomón, Edna Ríos-Valdovinos, Francisco Pola-Albores, Selene Lagunas-Rivera, Rosa Isela Cruz-Rodríguez, Kelly del Carmen Cruz-Salomón, Jesús Mauricio Ernesto Hernández-Méndez, María Emperatriz Domínguez-Espinosa
December 17, 2020 (v1)
Keywords: AGS acclimatization, anaerobic EGSB bioreactor, biomethane, BMP, cheese whey wastewater treatment, COD removal
Cheese whey wastewater (CWW) is the major by-product of the dairy industry. CWW is produced in large quantities, has varied characteristics and is usually disposed of. The disposal of CWW causes a negative impact on the environment of different agroindustrial areas due to the physic-chemical composition that significantly increases its high organic load and nutrients. For this reason, the aim of this work was to carry out an evaluation of the anaerobic treatability of an Expanded Granular Sludge Bed (EGSB) bioreactor as a new sustainable alternative for treatment of these effluents with bioenergy production. In this study, the bioreactor was operated under stable conditions (i.e., buffer index of 0.23 ± 0.1, pH 7.22 ± 0.4 and temperature 26.6 ± 1.4 °C) for 201 days. During evaluation the hydraulic retention time (HRT) was 6 and 8 days, and it was buffered with NaHCO3. At these conditions, the COD removal rate and biochemical methane potential (BMP) were 90, 92%; and 334, 328 mLCH4/gCOD... [more]
Adaptive Feedback Control for a Pasteurization Process
Emil D.J. Rasmussen, Massimiliano Errico, Stefania Tronci
December 17, 2020 (v1)
Keywords: adaptive control, milk, Modelling, pasteurization
The milk pasteurization process is nonlinear in nature, and for this reason, the application of linear control algorithms does not guarantee the obtainment of the required performance in every condition. The problem is here addressed by proposing an adaptive algorithm, which was obtained by starting from an observer-based control approach. The main result is the obtainment of a simple PI-like controller structure, where the control parameters depend on the state of the system and are adapted online. The proposed algorithm was designed and applied on a simulated process, where the temperature dependence of the milk’s physical properties was considered. The control strategy was tested by simulating different situations, particularly when time-varying disturbances entered the system. The use of the adaptive rule reduces the variance generally introduced by the PI or PID controller.
Hydrogenation of Trans,Trans-Muconic Acid to Bio-Adipic Acid: Mechanism Identification and Kinetic Modelling
Alessandro Rosengart, Carlo Pirola, Sofia Capelli
December 17, 2020 (v1)
Keywords: adipic acid, hydrogenation, kinetics, LHHW model, muconic acid, slurry reactor
The hydrogenation of trans,trans-muconic acid was investigated on a Pt/C 5% (wt) catalyst in a batch slurry reactor at constant hydrogen pressure (4 bar) and temperature (323, 333 and 343 K), with the purpose of developing a kinetic model able to predict conversions and product distributions. A dual-site Langmuir−Hinshelwood−Hougen−Watson (LHHW) model with hydrogen dissociation provided good fitting of the experimental data. The model parameters were regressed by robust numerical methods to overcome the computational challenges of the model parameters’ collinearity. Different reaction mechanisms were tested; the best model involved two subsequent hydrogenation steps. The first step yielded from trans,trans-muconic acid a monounsaturated intermediate (trans-2-hexenedioic acid), which was further hydrogenated to adipic acid in the second step. The intermediate was subjected to an equilibrium isomerization with cis-2-hexenedioic acid. The activation energy values and the rate constants we... [more]
The Attractiveness of the Ternary Rh-Pd-Pt Alloys for CO Oxidation Process
Aleksey A. Vedyagin, Yury V. Shubin, Roman M. Kenzhin, Pavel E. Plyusnin, Vladimir O. Stoyanovskii
December 17, 2020 (v1)
Keywords: catalytic activity, phase diagram, single precursor, synthesis, ternary alloys, thermolysis
Ternary alloys of platinum group metals attract a growing interest due to their unique catalytic properties. The present research is aimed to synthesize a series of Rh-Pd-Pt alloys with varied ratios of metals using a single-source precursor approach. Rhodium and palladium are partly miscible metals, while each of these metals is unlimitedly miscible with platinum. Thermolysis of complex salts used as a precursor results in the formation of metastable systems. The 3D nanostructure alloys are being formed after the complete decomposition of the single-source precursor. High-resolution transmission electron microscopic studies have shown that the nanoalloys are composed of interconnected polycrystalline ligaments with a mean diameter of 50 nm. The single-phase composition is confirmed by an X-ray diffraction analysis. The ratio of metals plays an important role in determining the catalytic activity of alumina-supported alloys and their thermal stability. According to UV-vis spectroscopy... [more]
Kinetic Analysis of Algae Gasification by Distributed Activation Energy Model
Guozhao Ji, Abdul Raheem, Xin Wang, Weng Fu, Boyu Qu, Yuan Gao, Aimin Li, Ming Zhao, Weiguo Dong, Zhien Zhang
December 17, 2020 (v1)
Keywords: activation energy distribution, algal biomass, gasification, kinetics
Conversion of algal biomass into energy products via gasification has attracted increasing research interests. A basic understanding of the gasification kinetics of algal biomass is of fundamental importance. Distributed activation energy model (DAEM), which provides the information of energy barrier distribution during the gasification process, is a promising tool to study the kinetic process of algae gasification. In this study, DAEM model was used to investigate Chlorella vulgaris and Spirulina gasification. The activation energy of Chlorella vulgaris gasification was in the range from 370 to 650 kJ mol−1. The range of activation energy for Spirulina gasification was a bit wider, spanning from 330 to 670 kJ mol−1. The distribution of activation energy for both Chlorella vulgaris and Spirulina showed that 500 kJ mol−1 had the most components, and these components were gasified at around 300 °C. The DAEM algorithm was validated by the conversion and conversion rate from experimental m... [more]
Biomass-Derived Activated Carbon as a Catalyst for the Effective Degradation of Rhodamine B dye
Shamim Ahmed Hira, Mohammad Yusuf, Dicky Annas, Hu Shi Hui, Kang Hyun Park
December 17, 2020 (v1)
Keywords: Activated carbon, activation energy, degradation, reaction rate, Rhodamine B
Activated carbon (AC) was fabricated from carrot waste using ZnCl2 as the activating agent and calcined at 700 °C for 2 h in a tube furnace. The as-synthesized AC was characterized using Fourier-transform infrared spectroscopy, X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Brunauer−Emmett−Teller analysis; the results revealed that it exhibited a high specific surface area and high porosity. Moreover, this material displayed superior catalytic activity for the degradation of toxic Rhodamine B (RhB) dye. Rate constant for the degradation of RhB was ascertained at different experimental conditions. Lastly, we used the Arrhenius equation and determined that the activation energy for the decomposition of RhB using AC was approximately 35.9 kJ mol−1, which was very low. Hopefully it will create a great platform for the degradation of other toxic dye in near future.
Non-Extractable Polyphenols from Food By-Products: Current Knowledge on Recovery, Characterisation, and Potential Applications
Yubin Ding, Ksenia Morozova, Matteo Scampicchio, Giovanna Ferrentino
December 17, 2020 (v1)
Keywords: antioxidants, characterisation, Extraction, food by-products, non-extractable polyphenols
Non-extractable polyphenols (NEPs), or bound polyphenols, are a significant fraction of polyphenols that are retained in the extraction residues after conventional aqueous organic solvent extraction. They include both high molecular weight polymeric polyphenols and low molecular weight phenolics attached to macromolecules. Current knowledge proved that these bioactive compounds possess high antioxidant, antidiabetic, and other biological activities. Plant-based food by-products, such as peels, pomace, and seeds, possess high amount of NEPs. The recovery of these valuable compounds is considered an effective way to recycle food by-products and mitigate pollution, bad manufacturing practice, and economic loss caused by the residues management. The current challenge to valorise NEPs from plant-based by-products is to increase the extraction efficiency with proper techniques, choose appropriate characterising methods, and explore potential functions to use in some products. Based on this s... [more]
Electrophysiological Effects of Extracellular Vesicles Secreted by Cardiosphere-Derived Cells: Unraveling the Antiarrhythmic Properties of Cell Therapies
Lidia Gómez-Cid, Marina Moro-López, Ana S. de la Nava, Ismael Hernández-Romero, Ana I. Fernández, Susana Suárez-Sancho, Felipe Atienza, Lilian Grigorian-Shamagian, Francisco Fernández-Avilés
December 17, 2020 (v1)
Subject: Biosystems
Keywords: antiarrhythmic effects, cell therapy, conduction velocity, extracellular vesicles, optical mapping
Although cell-based therapies show potential antiarrhythmic effects that could be mediated by their paracrine action, the mechanisms and the extent of these effects were not deeply explored. We investigated the antiarrhythmic mechanisms of extracellular vesicles secreted by cardiosphere-derived cell extracellular vesicles (CDC-EVs) on the electrophysiological properties and gene expression profile of HL1 cardiomyocytes. HL-1 cultures were primed with CDC-EVs or serum-free medium alone for 48 h, followed by optical mapping and gene expression analysis. In optical mapping recordings, CDC-EVs reduced the activation complexity of the cardiomyocytes by 40%, increased rotor meandering, and reduced rotor curvature, as well as induced an 80% increase in conduction velocity. HL-1 cells primed with CDC-EVs presented higher expression of SCN5A, CACNA1C, and GJA1, coding for proteins involved in INa, ICaL, and Cx43, respectively. Our results suggest that CDC-EVs reduce activation complexity by inc... [more]
Numerical Investigation of a Portable Incinerator: A Parametric Study
Mohsen Saffari Pour, Ali Hakkaki-Fard, Bahar Firoozabadi
December 17, 2020 (v1)
Keywords: combustion, computational fluid dynamics (CFD), parametric study, portable incinerator
The application of incinerators for the municipal solid waste (MSW) is growing due to the ability of such instruments to produce energy and, more specifically, reduce waste volume. In this paper, a numerical simulation of the combustion process with the help of the computational fluid dynamics (CFD) inside a portable (mobile) incinerator has been proposed. Such work is done to investigate the most critical parameters for a reliable design of a domestic portable incinerator, which is suitable for the Iranian food and waste culture. An old design of a simple incinerator has been used to apply the natural gas (NG), one of the available cheap fossil fuels in Iran. After that, the waste height, place of the primary burner, and the flow rate of the cooling air inside the incinerator, as the main parameters of the design, are investigated. A validation is also performed for the mesh quality test and the occurrence of the chemical reactions near the burner of the incinerator. Results proved th... [more]
Temperature Variation at Solid-Fluid Interface of Thin Film Lubricated Contact Problems
Szabolcs Szávai, Sándor Kovács
December 17, 2020 (v1)
Keywords: FEM, film, lubrication, Simulation, TEHD, temperature, thin, variation
Many calculating methods have been already developed for solving contact problems of parts such as gears, cams, and followers under fluid film lubrication conditions considering the temperature and pressure dependence. Similarly, the determination of the elasto-hydrodynamic pressure distribution the processes taking place in the lubricant and the contacting bodies, as well as in their environment, have to be dealt with simultaneously for the determination of the temperature field. A system of equation for the modelling of thermo-elastohydrodynamic lubrication between two contacting bodies containing hydrodynamic, thermodynamic, and strength problems is a highly non-linear system which becomes even more so if the temperature and pressure dependence of the material properties are considered. To solve this system, scientists started to use the finite element formulation in the 1960s and it was found to be a promising and reliable method. Earlier, the lubrication analysts used only the h-v... [more]
A Hybrid of Particle Swarm Optimization and Harmony Search to Estimate Kinetic Parameters in Arabidopsis thaliana
Mohamad Saufie Rosle, Mohd Saberi Mohamad, Yee Wen Choon, Zuwairie Ibrahim, Alfonso González-Briones, Pablo Chamoso, Juan Manuel Corchado
December 17, 2020 (v1)
Subject: Biosystems
Keywords: Arabidopsis thaliana, Harmony Search, parameter estimation, Particle Swarm Optimization
Recently, modelling and simulation have been used and applied to understand biological systems better. Therefore, the development of precise computational models of a biological system is essential. This model is a mathematical expression derived from a series of parameters of the system. The measurement of parameter values through experimentation is often expensive and time-consuming. However, if a simulation is used, the manipulation of computational parameters is easy, and thus the behaviour of a biological system model can be altered for a better understanding. The complexity and nonlinearity of a biological system make parameter estimation the most challenging task in modelling. Therefore, this paper proposes a hybrid of Particle Swarm Optimization (PSO) and Harmony Search (HS), also known as PSOHS, designated to determine the kinetic parameter values of essential amino acids, mainly aspartate metabolism, in Arabidopsis thaliana. Three performance measurements are used in this pap... [more]
Water Cycle Algorithm for Modelling of Fermentation Processes
Olympia Roeva, Maria Angelova, Dafina Zoteva, Tania Pencheva
December 17, 2020 (v1)
Keywords: fed-batch fermentation processes, Genetic Algorithm, parameter identification, water cycle algorithm
The water cycle algorithm (WCA), which is a metaheuristic method inspired by the movements of rivers and streams towards the sea in nature, has been adapted and applied here for the first time for solving such a challenging problem as the parameter identification of fermentation process (FP) models. Bacteria and yeast are chosen as representatives of FP models that are subjected to parameter identification due to their impact in different industrial fields. In addition, WCA is considered in comparison with the genetic algorithm (GA), which is another population-based technique that has been proved to be a promising alternative of conventional optimisation methods. The obtained results have been thoroughly analysed in order to outline the advantages and disadvantages of each algorithm when solving such a complicated real-world task. A discussion and a comparative analysis of both metaheuristic algorithms reveal the impact of WCA on model identification problems and show that the newly a... [more]
Estimating Limits of Detection and Quantification of Ibuprofen by TLC-Densitometry at Different Chromatographic Conditions
Josef Jampilek, Malgorzata Dolowy, Alina Pyka-Pajak
December 17, 2020 (v1)
Keywords: ibuprofen, limit of detection, limit of quantification, TLC-densitometry
Ibuprofen is one of the best-known nonsteroidal anti-inflammatory and analgesic drugs. Following the previous work, the current study is focused on estimating the effect of different chromatographic conditions on the sensitivity of thin-layer chromatography in combination with UV densitometry, i.e., the detection and quantification of ibuprofen in a wide range of its concentrations including the lowest limits of detection (LOD) and quantification (LOQ). For this purpose, a reliable and easy-to-use calculation procedure for LOD and LOQ determination is presented in this work. In addition, the impact of type plates and mobile phase composition on the LOD and LOQ, respectively, of this active substance is accurately described. The results of detection and the quantification level of ibuprofen obtained under applied chromatographic conditions confirmed the utility of silica gel plates as well as silica gel bonded phases (i.e., reversed-phase (RP) plates) in the thin-layer chromatography (T... [more]
Numerical Modeling of Equal and Differentiated Gas Injection in Ladles: Effect on Mixing Time and Slag Eye
Luis E. Jardón-Pérez, Carlos González-Rivera, Marco A. Ramirez-Argaez, Abhishek Dutta
December 17, 2020 (v1)
Keywords: dual gas injection, mixing time, numerical model, secondary refining, slag eye
Ladle refining plays a crucial role in the steelmaking process, in which a gas stream is bubbled through molten steel to improve the rate of removal of impurities and enhance the transport phenomena that occur in a metallurgical reactor. In this study, the effect of dual gas injection using equal (50%:50%) and differentiated (75%:25%) flows was studied through numerical modeling, using computational fluid dynamics (CFD). The effect of gas flow rate and slag thickness on mixing time and slag eye area were studied numerically and compared with the physical model. The numerical model agrees with the physical model, showing that for optimal performance the ladle must be operated using differentiated flows. Although the numerical model can predict well the hydrodynamic behavior (velocity and turbulent kinetic energy) of the ladle, there is a deviation from the experimental mixing time when using both equal and differentiated gas injection at a high gas flow rate and a high slag thickness. T... [more]
Influence of Different Smoking Procedures on Polycyclic Aromatic Hydrocarbons Formation in Traditional Dry Sausage Hercegovačka kobasica
Krešimir Mastanjević, Brankica Kartalović, Leona Puljić, Dragan Kovačević, Kristina Habschied
December 17, 2020 (v1)
Keywords: industrial smoking, PAH, smoking with open fire
The concentrations of 16 polycyclic aromatic hydrocarbons (PAH) in smoked dry sausage Hercegovačka kobasica were investigated. The sausages were stuffed in two different casings (collagen and natural) and smoked in traditional and industrial smokehouses. The highest concentration of PAH 16 were detected in sausages in natural casings smoked in the traditional manner. The samples smoked in the industrial chamber stuffed in collagen casing showed the lowest PAH 16 content. The content of PAH 4 in sausage smoked in the traditional way and stuffed in natural casing averaged 24.46 µg/kg, which is more the double of maximum prescribed concentration of 12 µg/kg. The concentration of cancerogenic benzo[a]pyrene averaged 7.79 µg/kg in sausage stuffed in natural casing and smoked in the traditional way, which is almost four times the legislative prescribed values (2 µg/kg). Sausage smoked in the traditional manner and stuffed in collagen casing showed lower values for PAH 4 (13.88 µg/kg) and ben... [more]
Analysis of Power Input of an In-Line Rotor-Stator Mixer for Viscoplastic Fluids
Mehmet Ayas, Jan Skocilas, Tomas Jirout
December 17, 2020 (v1)
Keywords: Herschel–Bulkley model, in-line rotor-stator mixer, laminar regime, Otto-Metzner coefficient, power draw
In this work, the power draw and shear profile of a novel in-line rotor-stator mixer were studied experimentally and the laminar flow regime was simulated. The power draw of the rotor-stator mixer was investigated experimentally using viscoplastic shear-thinning fluid and the results of the obtained power consumptions were verified through simulations. The power draw constant and Otto-Metzner coefficient were determined from the result of experimental data and through simulations. A new method is suggested for the determination of the Otto-Metzner coefficient for the Herschel−Bulkley model and the term efficiency is introduced. It was shown that the proposed method can be applied successfully for the prediction of the Otto-Metzner coefficient for the mixing of viscoplastic shear-thinning fluids. The effect of geometry and rotor speed on power consumption and shear rate profile in the investigated mixer is discussed from the results of the simulations. It was found that numerical method... [more]
Protective Effects of Active Compounds from Salviae miltiorrhizae Radix against Glutamate-Induced HT-22 Hippocampal Neuronal Cell Death
Hung Manh Phung, Sullim Lee, Ki Sung Kang
December 17, 2020 (v1)
Subject: Biosystems
Keywords: glutamate, HT-22, oxidative stress, Salvia miltiorrhiza Radix, tanshinone IIA
Oxidative stress is considered one of the factors that cause dysfunction and damage of neurons, causing diseases such as amyotrophic lateral sclerosis (ALS), Alzheimer’s disease (AD), and Parkinson’s disease (PD).Recently, natural antioxidant sources have emerged as one of the main research areas for the discovery of potential neuroprotectants that can be used to treat neurological diseases. In this research, we assessed the neuroprotective effect of a 70% ethanol Salvia miltiorrhiza Radix (SMR) extract and five of its constituent compounds (tanshinone IIA, caffeic acid, salvianolic acid B, rosmarinic acid, and salvianic acid A) in HT-22 hippocampal cells. The experimental data showed that most samples were effective in attenuating the cytotoxicity caused by glutamate in HT-22 cells, except for rosmarinic acid and salvianolic acid B. Of the compounds tested, tanshinone IIA (TS-IIA) exerted the strongest effect in protecting HT-22 cells against glutamate neurotoxin. Treatment with 400 n... [more]
Discrete Output Regulator Design for the Linearized Saint−Venant−Exner Model
Guilherme Ozorio Cassol, Stevan Dubljevic
December 17, 2020 (v1)
Keywords: discrete regulator, output regulation, system of hyperbolic PDEs, tracking
This manuscript addresses the regulator design in the discrete-time setting for the unstable linearized Saint−Venant−Exner model, which describes the dynamics of a sediment-filled water canal. The proposed regulator ensures the closed-loop stability and proper tracking of polynomial and periodic reference signals using output feedback in a sample-data setting. To design this regulator, the system discrete representation is achieved by the application of the structure-preserving Cayley-Tustin time discretization and the direct relation with the regulator in the continuous-time setting is shown. The regulator design in the continuous-time setting is developed using the backstepping methodology ensuring the closed-loop stability and the observer design, while the Sylvester equations are solved to achieve proper tracking. Finally, the numerical simulation results are presented to show the performance of the regulator.
Enhancing the Performance of HPAM Polymer Flooding Using Nano CuO/Nanoclay Blend
Saket Kumar, Roshan Tiwari, Maen Husein, Nitesh Kumar, Upendra Yadav
December 17, 2020 (v1)
Subject: Materials
Keywords: CEOR, nanoclay, nanohybrid, nanoparticle, polymer flooding, rheology
A single polymer flooding is a widely employed enhanced oil recovery method, despite polymer vulnerability to shear and thermal degradation. Nanohybrids, on the other hand, resist degradation and maintain superior rheological properties at different shear rates. In this article, the effect of coupling CuO nanoparticles (NPs) and nanoclay with partially hydrolyzed polyacrylamide (HPAM) polymer solution on the rheological properties and the recovery factor of the nanohybrid fluid was assessed. The results confirmed that the NP agents preserved the polymer chains from degradation under mechanical, chemical (i.e., salinity), and thermal stresses and maintained good extent of entanglement among the polymer chains, leading to a strong viscoelastic attribute, in addition to the pseudoplastic behavior. The NP additives increased the viscosity of the HPAM polymer at shear rates varying from 10−100 s−1. The rheological properties of the nanohybrid systems varied with the NP additive content, whi... [more]
Application of Detrended Fluctuation Analysis and Yield Stability Index to Evaluate Near Infrared Spectra of Green and Roasted Coffee Samples
Eszter Benes, Marietta Fodor, Sándor Kovács, Attila Gere
December 17, 2020 (v1)
Keywords: Coffea arabica, detrended fluctuation analysis, different roasting levels, grouping, yield stability index
Coffee quality, and therefore its price, is determined by coffee species and varieties, geographic location, the method used to process green coffee beans, and particularly the care taken during coffee production. Determination of coffee quality is often done by the nondestructive and fast near infrared spectroscopy (NIRS), which provides a huge amount of data about the samples. NIRS data require sophisticated, multivariate data analysis methods, such as principal component analysis, or linear discriminant analysis. Since the obtained data are a set of spectra, they can also be analyzed by signal processing methods. In the present study, the applications of two novel methods, detrended fluctuation analysis (DFA) and yield stability index (YSI), is introduced on NIR spectra of different roasting levels of coffee samples. Fourteen green coffee samples from all over the world have been roasted on three different levels and their NIR spectra were analyzed. DFA successfully differentiated t... [more]
Real-Time Decision-Support System for High-Mix Low-Volume Production Scheduling in Industry 4.0
Balázs Kocsi, Michael Maiko Matonya, László Péter Pusztai, István Budai
December 17, 2020 (v1)
Keywords: decision-support system, HMLV production, Industry 4.0, real-time production-scheduling techniques, risk analysis, RPA
Numerous organizations are striving to maximize the profit of their businesses by the effective implementation of competitive advantages including cost reduction, quick delivery, and unique high-quality products. Effective production-scheduling techniques are methods that many firms use to attain these competitive advantages. Implementing scheduling techniques in high-mix low-volume (HMLV) manufacturing industries, especially in Industry 4.0 environments, remains a challenge, as the properties of both parts and processes are dynamically changing. As a reaction to these challenges in HMLV Industry 4.0 manufacturing, a newly advanced and effective real-time production-scheduling decision-support system model was developed. The developed model was implemented with the use of robotic process automation (RPA), and it comprises a hybrid of different advanced scheduling techniques obtained as the result of analytical-hierarchy-process (AHP) analysis. The aim of this research was to develop a... [more]
Evolution of Specific Heat Capacity with Temperature for Typical Supports Used for Heterogeneous Catalysts
Xiaojia Lu, Yanjun Wang, Lionel Estel, Narendra Kumar, Henrik Grénman, Sébastien Leveneur
December 17, 2020 (v1)
Subject: Materials
Keywords: heterogeneous catalytic material, micro-calorimeter C80, specific heat capacity
Heterogeneous catalysts are widely used in the chemical industry. Compared with homogeneous catalysts, they can be easily separated from the reaction mixture. To design and optimize an efficient and safe chemical process one needs to calculate the energy balance, implying the need for knowledge of the catalyst’s specific heat capacity. Such values are typically not reported in the literature, especially not the temperature dependence. To fill this gap in knowledge, the specific heat capacities of commonly utilized heterogeneous catalytic supports were measured at different temperatures in a Tian−Calvet calorimeter. The following materials were tested: activated carbon, aluminum oxide, amberlite IR120 (H-form), H-Beta-25, H-Beta-38, H-Y-60, H-ZSM-5-23, H-ZSM-5-280, silicon dioxide, titanium dioxide, and zeolite 13X. Polynomial expressions were successfully fitted to the experimental data.
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