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Showing records 1 to 25 of 71. [First] Page: 1 2 3 Last
Impact of Hot-Melt-Extrusion on Solid-State Properties of Pharmaceutical Polymers and Classification Using Hierarchical Cluster Analysis
Ioannis Partheniadis, Miltiadis Toskas, Filippos-Michail Stavras, Georgios Menexes, Ioannis Nikolakakis
April 16, 2021 (v1)
Keywords: classification, dendrograms, factor analysis, hot-melt extrusion, Polymers, powders
The impact of hot-melt extrusion (HME) on the solid-state properties of four methacrylic (Eudragit® L100-55, Eudragit® EPO, Eudragit® RSPO, Eudragit® RLPO) and four polyvinyl (Kollidon® VA64, Kollicoat® IR, Kollidon® SR, and Soluplus®) polymers was studied. Overall, HME decreased Tg but increased electrostatic charge and surface free energy. Packing density decreased with electrostatic charge, whereas Carr’s and Hausner indices showed a peak curve dependency. Overall, HME reduced work of compaction (Wc), deformability (expressed as Heckel PY and Kawakita 1/b model parameters and as slope S′ of derivative force/displacement curve), and tablet strength (TS) but increased elastic recovery (ER). TS showed a better correlation with S′ than PY and 1/b. Principal component analysis (PCA) organized the data of neat and extruded polymers into three principal components explaining 72.45% of the variance. The first included Wc, S′ and TS with positive loadings expressing compaction, and ER with n... [more]
Effect of Hydration Layer on the Adsorption of Dodecane Collector on Low-Rank Coal: A Molecular Dynamics Simulation Study
Lingyun Liu, Erle Qiao, Liang Shen, Fanfei Min, Changguo Xue
April 16, 2021 (v1)
Keywords: Adsorption, hydration layer, low-rank coal, molecular dynamics simulation
The hydration layer has a significant effect on the adsorption behavior of reagents during the flotation process of low-rank coal. Understanding the effect of hydration layer on the adsorption of common collectors on low-rank coal is a prerequisite for proposing a new enhanced coal floatation method. In this study, a smooth low-rank coal surface model with a density of 1.2 g/cm3 was constructed and compared with the XPS results. Three different systems, coal-water, coal-collector, and coal-water-collector, were constructed. Molecular dynamics method was applied to study the adsorption behaviors of water and dodecane molecules. Simulation results revealed that a stable hydration layer with a thickness of about 5 Å was formed due to the strong attraction of coal surface. The negative value of interaction energy (IE) indicated that dodecane molecules could spontaneously adsorb on the coal surface. Dodecane molecules were successfully adsorbed on the coal surface when it was located inside... [more]
A Confidence Interval-Based Process Optimization Method Using Second-Order Polynomial Regression Analysis
Jungwon Yu, Soyoung Yang, Jinhong Kim, Youngjae Lee, Kil-Taek Lim, Seiki Kim, Sung-Soo Ryu, Hyeondeok Jeong
April 16, 2021 (v1)
Keywords: ball mill, confidence interval, process optimization, second-order polynomial regression analysis
In the manufacturing processes, process optimization tasks, to optimize their product quality, can be performed through the following procedures. First, process models mimicking functional relationships between quality characteristics and controllable factors are constructed. Next, based on these models, objective functions formulating process optimization problems are defined. Finally, optimization algorithms are applied for finding solutions for these functions. It is important to note that different solutions can be found whenever these algorithms are independently executed if a unique solution does not exist; this may cause confusion for process operators and engineers. This paper proposes a confidence interval (CI)-based process optimization method using second-order polynomial regression analysis. This method evaluates the quality of the different solutions in terms of the lengths of their CIs; these CIs enclose the outputs of the regression models for these solutions. As the CIs... [more]
Computational Optimization of Porous Structures for Electrochemical Processes
Nicole Vorhauer-Huget, Haashir Altaf, Robert Dürr, Evangelos Tsotsas, Tanja Vidaković-Koch
April 16, 2021 (v1)
Subject: Materials
Keywords: drainage invasion, model upscaling, permeability, pore network model, pore size distribution, porosity gradient, porous media, porous transport layer, water electrolysis
Porous structures are naturally involved in electrochemical processes. The specific architectures of the available porous materials, as well as their physical properties, crucially affect their applications, e.g., their use in fuel cells, batteries, or electrolysers. A key point is the correlation of transport properties (mass, heat, and charges) in the spatially—and in certain cases also temporally—distributed pore structure. In this paper, we use mathematical modeling to investigate the impact of the pore structure on the distribution of wetting and non-wetting phases in porous transport layers used in water electrolysis. We present and discuss the potential of pore network models and an upscaling strategy for the simulation of the saturation of the pore space with liquid and gas, as well as the computation of the relative permeabilities and oxygen dissolution and diffusion. It is studied how a change of structure, i.e., the spatial grading of the pore size distribution and porosity,... [more]
Solubilization, Hansen Solubility Parameters, Solution Thermodynamics and Solvation Behavior of Flufenamic Acid in (Carbitol + Water) Mixtures
Faiyaz Shakeel, Sultan Alshehri
April 16, 2021 (v1)
Subject: Other
Keywords: carbitol, cosolvent mixtures, flufenamic acid, solubility, solution thermodynamics
The solubilization, solution thermodynamics, solvation behavior and Hansen solubility parameters (HSPs) of an anti-inflammatory medicine flufenamic acid (FFA) in various Carbitol + water mixtures were evaluated in this study. The experimental solubility of FFA in mole fraction (xe) was measured at T = 298.2−318.2 K and p = 0.1 MPa using a static equilibrium method. The xe values of FFA in various Carbitol + water mixtures were correlated with van’t Hoff, Apelblat, Yalkowsky−Roseman, Jouyban−Acree and Jouyban−Acree−van’t Hoff models. All the studied models showed good correlation with mean error values of less than 2%. The xe value of FFA was found to increase significantly with the increase in temperature and Carbitol mass fraction in all Carbitol + water mixtures evaluated. The maximum and minimum xe values of FFA were recorded in pure Carbitol (2.81 × 10−1) at T = 318.2 K and pure water (5.80 × 10−7) at T = 298.2 K, respectively. Moreover, the HSP of FFA was found to be more closed w... [more]
Optimal-Setpoint-Based Control Strategy of a Wastewater Treatment Process
Sergiu Caraman, Laurentiu Luca, Iulian Vasiliev, Marian Barbu
April 16, 2021 (v1)
Keywords: fuzzification block, Genetic Algorithm, optimal-setpoint-based control strategy, performance criterion, wastewater treatment process
This paper presents an optimal-setpoint-based control strategy of a wastewater treatment process (WWTP). The treatment plant serves the city of Galati, located in Eastern Romania, a city with a population of 250,000 inhabitants. As the treatment plant includes several control loops (based upon PI controllers), an efficient operation means the establishing of an optimal operating point regardless of the pluviometric regime (DRY, RAIN and STORM) or transitions between regimes. This optimal operating point is given by the optimal setpoint set (setpoints of the dissolved oxygen concentration in the aerated tanks, setpoint of the nitrate concentration, external recirculation flow, sludge flow extracted from the primary clarifier and excess sludge flow from the secondary clarifier) of the treatment plant control loops. The control algorithm has two distinct parts: the first part consists of computing the optimal aforementioned setpoints, based on the mathematical model of the treatment plant... [more]
Improvement of Energy Efficiency and Productivity in an Electric Arc Furnace through the Modification of Side-Wall Injector Systems
Yonmo Sung, Sangyoun Lee, Kyungmoon Han, Jaduck Koo, Seongjae Lee, Doyoung Jang, Changyong Oh, Byunghwa Jang
April 16, 2021 (v1)
Keywords: electric arc furnace, energy savings, Natural Gas, oxy-fuel burner, oxygen lancing, steelmaking
The energy cost of producing steel in an electric arc furnace (EAF) has a sizable influence on the prices of natural gas and electricity. Therefore, it is important to use these energies efficiently via a tailored oxy-fuel combustion burner and oxygen lance. In this study, an important modification of the side-wall injector system in the EAF at Hyundai Steel Incheon works was implemented to reduce electrical energy consumption and improve productivity. A protruding water-cooled copper jacket, including a newly designed burner, was developed to reduce the distance between the jet nozzle and the molten steel. In addition, the jet angles for the burner and lance were separately set for each scrap melting and refining mode. The modifications led to a reduction in electrical energy consumption of 5 kWh/t and an increase in productivity of approximately 3.1 t/h. Consequently, total energy cost savings of 0.3 USD/t and a corresponding annual cost savings of approximately 224,000 USD/year were... [more]
Hydrothermal Carbonization of Olive Tree Pruning as a Sustainable Way for Improving Biomass Energy Potential: Effect of Reaction Parameters on Fuel Properties
Judith González-Arias, Marta Elena Sánchez, Elia Judith Martínez, Camila Covalski, Ana Alonso-Simón, Rubén González, Jorge Cara-Jiménez
April 16, 2021 (v1)
Keywords: bioconversion, bioenergy, biofuel, combustion, hydrochar, hydrothermal carbonization, olive tree pruning biomass
Hydrothermal carbonization (HTC) allows the conversion of organic waste into a solid product called hydrochar with improved fuel properties. Olive tree pruning biomass (OTP), a very abundant residue in Mediterranean countries, was treated by HTC to obtain a solid fuel similar to coal that could be used in co-combustion processes. Three different reaction temperatures (220, 250, and 280 °C) and reaction times (3, 6, and 9 h) were selected. The hydrochars obtained were extensively analyzed to study their behavior as fuel (i.e., ultimate, proximate, fiber and thermogravimetric analysis, Fourier-transform infrared spectroscopy (FTIR), activation energy, and combustion performance). The concentrations of cellulose, hemicellulose, and lignin in the samples depict a clear and consistent trend with the chemical reactions carried out in this treatment. Regarding O/C and H/C ratios and HHV, the hydrochars generated at more severe conditions are similar to lignite coal, reaching values of HHV up... [more]
Connecting Risk and Resilience for a Power System Using the Portland Hills Fault Case Study
Vishvas H. Chalishazar, Ted K. A. Brekken, Darin Johnson, Kent Yu, James Newell, King Chin, Rob Weik, Emilie Dierickx, Matthew Craven, Maty Sauter, Andrey Olennikov, Jennifer Galaway, Ann Radil
April 16, 2021 (v1)
Keywords: economic risk analysis, monte carlo simulations, peak ground acceleration, power transmission system, seismic resilience
Active seismic faults in the Pacific Northwest area have encouraged electric utilities in the region to deeply contemplate and proactively intervene to support grid resilience. To further this effort this research introduces Monte Carlo (MC)-based power system modeling as a means to inform the Performance Based Earthquake Engineering method and simulates 100,000 sample earthquakes of a 6.8 magnitude (M6.8) Portland Hills Fault (PHF) scenario in the Portland General Electric (PGE) service territory as a proof of concept. This paper also proposes the resilience metric Seismic Load Recovery Factor (SLRF) to quantify the recovery of a downed power system and thus can be used to quantify earthquake economic risk. Using MC results, the SLRF was evaluated to be 19.7 h and the expected economic consequence cost of a M6.8 PHF event was found to be $180 million with an annualized risk of $90,000 given the event’s 1 in 2000 year probability of occurrence. The MC results also identified the eight... [more]
A Representation of Membrane Computing with a Clustering Algorithm on the Graphical Processing Unit
Ravie Chandren Muniyandi, Ali Maroosi
April 16, 2021 (v1)
Subject: Other
Keywords: CUDA, GPU kernel execution, GPU multiprocessor occupancy, membrane systems, parallel computing
Long-timescale simulations of biological processes such as photosynthesis or attempts to solve NP-hard problems such as traveling salesman, knapsack, Hamiltonian path, and satisfiability using membrane systems without appropriate parallelization can take hours or days. Graphics processing units (GPU) deliver an immensely parallel mechanism to compute general-purpose computations. Previous studies mapped one membrane to one thread block on GPU. This is disadvantageous given that when the quantity of objects for each membrane is small, the quantity of active thread will also be small, thereby decreasing performance. While each membrane is designated to one thread block, the communication between thread blocks is needed for executing the communication between membranes. Communication between thread blocks is a time-consuming process. Previous approaches have also not addressed the issue of GPU occupancy. This study presents a classification algorithm to manage dependent objects and membra... [more]
Design and Characterization of a Fluidic Device for the Evaluation of SIS-Based Vascular Grafts
Alejandra Riveros, Monica Cuellar, Paolo F. Sánchez, Carolina Muñoz-Camargo, Juan C. Cruz, Néstor Sandoval, Omar D. Lopez Mejia, Juan C. Briceño
April 16, 2021 (v1)
Subject: Biosystems
Keywords: computational fluid dynamics (CFD), fluidic system, human umbilical vein endothelial cells (HUVEC) growth, porcine intestinal submucosa (SIS), vascular graft
Currently available small diameter vascular conduits present several long-term limitations, which has prevented their full clinical implementation. Commercially available vascular grafts show no regenerative capabilities and eventually require surgical replacement; therefore, it is of great interest to develop alternative regenerative vascular grafts (RVG). Decellularized Small Intestinal Submucosa (SIS) is an attractive material for RVG, however, the evaluation of the performance of these grafts is challenging due to the absence of devices that mimic the conditions found in vivo. Thereby, the objective of this study is to design, manufacture and validate in silico and in vitro, a novel fluidic system for the evaluation of human umbilical vein endothelial cells (HUVECs) proliferation on SIS-based RVG under dynamical conditions. Our perfusion and rotational fluidic system was designed in Autodesk Inventor 2018. In silico Computational Fluid Dynamics (CFD) validation of the system was ca... [more]
Enhanced Adsorptive Removal of β-Estradiol from Aqueous and Wastewater Samples by Magnetic Nano-Akaganeite: Adsorption Isotherms, Kinetics, and Mechanism
Anele Mpupa, Azile Nqombolo, Boris Mizaikoff, Philiswa Nosizo Nomngongo
April 16, 2021 (v1)
Keywords: adsorptive removal, akaganeite nanorods, desirability function, endocrine disruptors, β-estradiol
A surfactant-free method was used to synthesize iron oxyhydroxide (akaganeite, β-FeOOH) nanorods and characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDS), and transmission electron microscopy (TEM). The synthesized nanoadsorbent was applied for the adsorptive removal of β-estradiol from aqueous solutions. The parameters affecting the adsorption were optimized using a multivariate approach based on the Box−Behnken design with the desirability function. Under the optimum conditions, the equilibrium data were investigated using two and three parameter isotherms, such as the Langmuir, Freundlich, Dubinin−Radushkevich, Redlich−Peterson, and Sips models. The adsorption data were described as Langmuir and Sips isotherm models and the maximum adsorption capacities in Langmuir and Sips of the β-FeOOH nanorods were 97.0 and 103 mg g−1, respectively. The adjusted non-l... [more]
Investigating the Use of Recycled Pork Fat-Based Biodiesel in Aviation Turbo Engines
Grigore Cican, Marius Deaconu, Radu Mirea, Laurentiu Ceatra, Mihaiella Cretu, Tănase Dobre
April 16, 2021 (v1)
Keywords: bio-aviation fuel, biodiesel, recycled pork fat, turbo engine performance
This paper presents an analysis of the possibility of using recycled pork fat-based biodiesel as fuel for aviation turbo-engines. The analysis consists of the assessment of four blends of Jet A kerosene with 10%, 30%, 50%, and 100% biodiesel and pure Jet A that was used as reference in the study. The first part of the paper presents the physical-chemical properties of the blends: density, viscosity, flash point, freezing point, and calorific power. Through Fourier transform infrared spectroscopy (FTIR) analysis, a benchmark was performed on the mixtures of Jet A with 10%, 20%, 30%, 50%, and 100% biodiesel compared with Jet A. The second part of the paper presents the test results of these blends used for fuelling a Jet Cat P80 turbo engine at the Turbo Engines Laboratory of the Aerospace Engineering Faculty of Polyethnic University of Bucharest. These functional tests were performed using different operating regimes as follows: idle, cruise, intermediate, and maximum. For each regime,... [more]
Cu(II) and As(V) Adsorption Kinetic Characteristic of the Multifunctional Amino Groups in Chitosan
Byungryul An
April 16, 2021 (v1)
Keywords: Adsorption, amino group, anion, cation, kinetic, multifunction
Amino groups in the chitosan polymer play as a functional group for the removal of cations and anions depending on the degree of protonation, which is determined by the solution pH. A hydrogel beadlike porous adsorbent was used to investigate the functions and adsorption mechanism of the amino groups by removal of Cu(II) as a cation and As(V) as an anion for a single and mixed solution. The uptakes of Cu(II) and As(V) were 5.2 and 5.6 μmol/g for the single solution and 5.9 and 3.6 μmol/g for the mixed solution, respectively. The increased total capacity in the presence of both the cation and anion indicated that the amino group (NH2 or NH3+) species was directly associated for adsorption. The application of a pseudo second-order (PSO) kinetic model was more suitable and resulted in an accurate correlation coefficient (R2) compared with the pseudo first-order (PFO) kinetic model for all experimental conditions. Due to poor linearization of the PFO reaction model, we attempted to divide... [more]
Curation and Analysis of a Saccharomyces cerevisiae Genome-Scale Metabolic Model for Predicting Production of Sensory Impact Molecules under Enological Conditions
William T. Scott Jr, Eddy J. Smid, Richard A. Notebaart, David E. Block
April 16, 2021 (v1)
Subject: Biosystems
Keywords: aroma, flux balance analysis (FBA), genome-scale metabolic models, Saccharomyces cerevisiae, wine fermentation
One approach for elucidating strain-to-strain metabolic differences is the use of genome-scale metabolic models (GSMMs). To date GSMMs have not focused on the industrially important area of flavor production and, as such; do not cover all the pathways relevant to flavor formation in yeast. Moreover, current models for Saccharomyces cerevisiae generally focus on carbon-limited and/or aerobic systems, which is not pertinent to enological conditions. Here, we curate a GSMM (iWS902) to expand on the existing Ehrlich pathway and ester formation pathways central to aroma formation in industrial winemaking, in addition to the existing sulfur metabolism and medium-chain fatty acid (MCFA) pathways that also contribute to production of sensory impact molecules. After validating the model using experimental data, we predict key differences in metabolism for a strain (EC 1118) in two distinct growth conditions, including differences for aroma impact molecules such as acetic acid, tryptophol, and h... [more]
Analysis and Anticancer Effects of Active Compounds from Spatholobi Caulis in Human Breast Cancer Cells
Hung Manh Phung, Hesol Lee, Sullim Lee, Dongyeop Jang, Chang-Eop Kim, Ki Sung Kang, Chang-Seob Seo, You-Kyung Choi
April 16, 2021 (v1)
Subject: Biosystems
Keywords: apoptosis, breast cancer, gallic acid, MCF-7, network pharmacology, p53, Spatholobi Caulis
Breast cancer is the most common malignancy in both developing and developed countries. In this study, we simultaneously analyzed nine constituent compounds from Spatholobi Caulis (gallic acid, (−)-gallocatechin, 3,4-dihydroxybenzoic acid, procyanidin B1, 3,4-dihydroxybenzaldehyde, catechin, procyanidin B2, epicatechin, and (−)-epicatechin gallate) and examined their anticancer effects on MCF-7 and MDA-MB-231 human breast cancer cells. The experimental results indicated that the gallic acid showed the strongest cytotoxic effect on MCF-7 cells among tested compounds whilst most of samples did not express inhibitory effect on viability of MDA-MB-231 cells, except for 70% ethanol extract of S. Caulis. Thus, gallic acid was chosen to extend anticancer mechanism study on MCF-7 cells. Our data showed that the gallic acid induced apoptotic MCF-7 cell death through both extrinsic and intrinsic pathways, which increased the expression of cleaved caspase-7, -8, and -9, Bax and p53, but reduced t... [more]
Numerical Simulation of Axial Vortex in a Centrifugal Pump as Turbine with S-Blade Impeller
Xiaohui Wang, Kailin Kuang, Zanxiu Wu, Junhu Yang
April 16, 2021 (v1)
Keywords: energy recovery, hydraulic losses, pressure fluctuation, pump as turbine, vortex
Pump as turbines (PATs) are widely applied for recovering the dissipated energy of high-pressure fluids in several hydraulic energy resources. When a centrifugal pump operates as turbine, the large axial vortex occurs usually within the impeller flow passages. In view of the structure and evolution of the vortex, and its effect on pressure fluctuation and energy conversion of the machine, a PAT with specific-speed 9.1 was analyzed based on detached eddy simulation (DES), and the results showed that vortices generated at the impeller inlet region, and the size and position of detected vortices, were fixed as the impeller rotated. However, the swirling strength of vortex cores changed periodically with double rotational frequency. The influence of vortices on pressure fluctuation of PAT was relatively obvious, deteriorating the operating stability of the machine evidently. In addition, the power loss near impeller inlet region was obviously heavy as the impact of large axial vortices, wh... [more]
Inhibitory Effects of Thymol Isolated from Curcuma longa L. on Adipogenesis in HepG2 Cells
Dam-Hee Kang, Young-Seob Lee, Seon Min Oh, Dahye Yoon, Doo Jin Choi, Dong-Yeul Kwon, Ok-Hwa Kang, Dae Young Lee
April 16, 2021 (v1)
Subject: Biosystems
Keywords: Curcuma longa L., hepatoprotective effect, HepG2, NAFLD, quantification, thymol
Non-alcoholic fatty liver disease (NAFLD) is a disease associated with metabolic syndromes such as diabetes and obesity, regardless of alcohol consumption, and refers to the accumulation of triacylglycerols in the liver. Thymol (THY) is a vegetable essential oil that is naturally contained in the Zingiberaceae and Lamiaceae families. THY was isolated from Curcuma longa L. The rhizomes of Curcuma longa L. were dried, sliced and extracted with 50% ethanol and then isolated through repeated column chromatography. This study was conducted to investigate the inhibitory effect of THY, even in non-alcoholic fatty liver disease, in relation to the inhibiting hyperlipidemia effect of THY, which was demonstrated in previous studies. Hepatocytes were treated with oleate (OA) containing THY to observe lipid accumulation by Oil Red O staining (ORO). We also tested the effect of THY on triacylglycerols (TG) and total cholesterol (TC) in HepG2 cells. Western blot and real-time RT-PCR using sterol reg... [more]
Microwave-Assisted Pyrolysis of Biomass Waste: A Mini Review
Saleem Ethaib, Rozita Omar, Siti Mazlina Mustapa Kamal, Dayang Radiah Awang Biak, Salah L. Zubaidi
April 16, 2021 (v1)
Keywords: bio-char, bio-oil, Biomass, microwave-assisted pyrolysis, operating parameters
The utilization of biomass waste as a raw material for renewable energy is a global concern. Pyrolysis is one of the thermal treatments for biomass wastes that results in the production of liquid, solid and gaseous products. Unfortunately, the complex structure of the biomass materials matrix needs elevated heating to convert these materials into useful products. Microwave heating is a promising alternative to conventional heating approaches. Recently, it has been widely used in pyrolysis due to easy operation and its high heating rate. This review tries to identify the microwave-assisted pyrolysis treatment process fundamentals and discusses various key operating parameters which have an effect on product yield. It was found that several operating parameters govern this process such as microwave power and the degree of temperature, microwave absorber addition and its concentration, initial moisture content, initial sweep gas flow rate/residence time. Moreover, this study highlighted t... [more]
Carbon-Efficient Production Scheduling of a Bioethanol Plant Considering Diversified Feedstock Pelletization Density: A Case Study
Xinchao Li, Xin Jin, Shan Lu, Zhe Li, Yue Wang, Jiangtao Cao
April 16, 2021 (v1)
Keywords: bioethanol plant, carbon emission, dual-objective optimization, Scheduling
This paper presents a dual-objective optimization model for production scheduling of bioethanol plant with carbon-efficient strategies. The model is developed throughout the bioethanol production process. Firstly, the production planning and scheduling of the bioethanol plant’s transportation, storage, pretreatment, and ethanol manufacturing are fully considered. Secondly, the carbon emissions in the ethanol manufacturing process are integrated into the model to form a dual-objective optimization model that simultaneously optimizes the production plan and carbon emissions. The effects of different biomass raw materials with optional pelletization density and pretreatment methods on production scheduling are analyzed. The influence of demand and pretreatment cost on selecting a pretreatment method and total profit is considered. A membership weighted method is developed to solve the dual-objective model. The carbon emission model and economic model are integrated into one model for anal... [more]
Potential Dynamics of CO2 Stream Composition and Mass Flow Rates in CCS Clusters
Sven-Lasse Kahlke, Martin Pumpa, Stefan Schütz, Alfons Kather, Heike Rütters
April 16, 2021 (v1)
Keywords: CCS, CO2 quality, energy mix, impurities, pipeline transport
Temporal variations in CO2 stream composition and mass flow rates may occur in a CO2 transport network, as well as further downstream when CO2 streams of different compositions and temporally variable mass flow rates are fed in. To assess the potential impacts of such variations on CO2 transport, injection, and storage, their characteristics must be known. We investigated variation characteristics in a scenario of a regional CO2 emitter cluster of seven fossil-fired power plants and four industrial plants that feed captured CO2 streams into a pipeline network. Variations of CO2 stream composition and mass flow rates in the pipelines were simulated using a network analysis tool. In addition, the potential effects of changes in the energy mix on resulting mass flow rates and CO2 stream compositions were investigated for two energy mix scenarios that consider higher shares of renewable energy sources or a replacement of lignite by hard coal and natural gas. While resulting maximum mass fl... [more]
Experimental Investigation of Stability of Vegetable Oils Used as Dielectric Fluids for Electrical Discharge Machining
Maria-Crina Radu, Raluca Tampu, Valentin Nedeff, Oana-Irina Patriciu, Carol Schnakovszky, Eugen Herghelegiu
April 16, 2021 (v1)
Keywords: EDM, FTIR, refractive index, UV/Vis, vegetable oil, viscosity
One main drawback of electrical discharge machining (EDM) is related to the dielectric fluid, since it impacts both the environment and operator health and safety. To resolve these issues, recent research has demonstrated the technical feasibility and qualitative performance of vegetable oils as substitutes for hydrocarbon-based dielectric and synthetic oils in EDM. However, due to the higher content of unsaturated fatty acids, vegetable oils lose their stability, due to several factors such as heating or exposure to light or oxygen. The present study is a first attempt to analyze the extent to which the physic-chemical properties of vegetable oils change during EDM processing. Refractive index, dynamic viscosity and spectra analyses were conducted for sunflower and soybean oils. The results revealed that, under the applied processing conditions, no structural changes occurred. These findings are very promising from the perspective of EDM sustainability.
Maintaining Physicochemical, Microbiological, and Sensory Quality of Pineapple Juice (Ananas comosus, Var. ‘Queen Victoria’) through Mild Heat Treatment
Charlène Leneveu-Jenvrin, Baptiste Quentin, Sophie Assemat, Fabienne Remize
April 16, 2021 (v1)
Keywords: beverage, fruit, seasonal variations, variability
Shelf life of freshly prepared pineapple juice is short and requires refrigerated conditions of storage. Mild heat treatment remains the easiest way to prolong juice shelf life for small companies. This study was constructed to assess pineapple cv. Queen Victoria juice shelf life from a broad examination of its quality and to propose the most appropriate thermal treatment to increase shelf life without any perceptible decrease in quality. From 25 independent batches of pineapple, collected in different areas and seasons from Reunion Island, the variability of juice physicochemical and microbiological quality was determined. Juice pH values were the highest for fruit harvested in summer, but the juice acidity remained low enough to prevent pathogen spore-forming bacteria growth. During storage at 4 °C, color was modified, and yeasts and molds were the main microbial group exhibiting growth. Assessment of sensory quality resulted in the proposal of a shelf life comprising between three a... [more]
Finite Element Study of Magnetohydrodynamics (MHD) and Activation Energy in Darcy−Forchheimer Rotating Flow of Casson Carreau Nanofluid
Bagh Ali, Ghulam Rasool, Sajjad Hussain, Dumitru Baleanu, Sehrish Bano
April 16, 2021 (v1)
Keywords: Carreau fluid, finite element method, heat transfer, MHD, nanofluid, rotating Casson fluid
Here, a study for MHD (magnetohydrodynamic) impacts on the rotating flow of Casson Carreau nanofluids is considered. The temperature distribution is associated with thermophoresis, Brownian motion, and heat source. The diffusion of chemically reactive specie is investigated with Arrhenius activation energy. The governing equations in the 3D form are changed into dimensionless two-dimensional form with the implementation of suitable scaling transformations. The Variational finite element procedure is harnessed and coded in Matlab script to obtain the numerical solution of the coupled non-linear partial differential problem. The variation patterns of Sherwood number, Nusselt number, skin friction coefficients, velocities, concentration, and temperature functions are computed to reveal the physical nature of this examination. It is seen that higher contributions of the magnetic force, Casson fluid, and rotational fluid parameters cause a raise in the temperature like thermophoresis and Br... [more]
Methodology to Solve the Multi-Objective Optimization of Acrylic Acid Production Using Neural Networks as Meta-Models
Geraldine Cáceres Sepulveda, Silvia Ochoa, Jules Thibault
April 16, 2021 (v1)
Keywords: acrylic acid production, artificial neural networks, multi-objective optimization, Pareto domain, Surrogate Model
It is paramount to optimize the performance of a chemical process in order to maximize its yield and productivity and to minimize the production cost and the environmental impact. The various objectives in optimization are often in conflict, and one must determine the best compromise solution usually using a representative model of the process. However, solving first-principle models can be a computationally intensive problem, thus making model-based multi-objective optimization (MOO) a time-consuming task. In this work, a methodology to perform the multi-objective optimization for a two-reactor system for the production of acrylic acid, using artificial neural networks (ANNs) as meta-models, is proposed in an effort to reduce the computational time required to circumscribe the Pareto domain. The performance of the meta-model confirmed good agreement between the experimental data and the model-predicted values of the existent relationships between the eight decision variables and the n... [more]
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