Records Added in May 2021
Records added in May 2021
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Showing records 136 to 160 of 160. [First] Page: 1 3 4 5 6 7 Last
Computer-Aided Nonlinear Frequency Response Method for Investigating the Dynamics of Chemical Engineering Systems
Luka A. Živković, Tanja Vidaković-Koch, Menka Petkovska
May 11, 2021 (v1)
Keywords: experimental identification, frequency response functions, nonlinear process dynamics, periodic processes, Process Intensification, process systems engineering
The Nonlinear Frequency Response (NFR) method is a useful Process Systems Engineering tool for developing experimental techniques and periodic processes that exploit the system nonlinearity. The basic and most time-consuming step of the NFR method is the derivation of frequency response functions (FRFs). The computer-aided Nonlinear Frequency Response (cNFR) method, presented in this work, uses a software application for automatic derivation of the FRFs, thus making the NFR analysis much simpler, even for systems with complex dynamics. The cNFR application uses an Excel user-friendly interface for defining the model equations and variables, and MATLAB code which performs analytical derivations. As a result, the cNFR application generates MATLAB files containing the derived FRFs in a symbolic and algebraic vector form. In this paper, the software is explained in detail and illustrated through: (1) analysis of periodic operation of an isothermal continuous stirred-tank reactor with a sim... [more]
Effect of Pasteurisation on Methane Yield from Food Waste and Other Substrates in Anaerobic Digestion
Yue Zhang, Sigrid Kusch-Brandt, Sonia Heaven, Charles J. Banks
May 11, 2021 (v1)
Keywords: anaerobic digestion, animal by-products regulation, food waste, methane yield, pasteurisation
The effect of pasteurisation and co-pasteurisation on biochemical methane potential values in anaerobic digestion (AD) was studied. Pasteurisation prior to digestion in a biogas plant is a common hygienisation method for organic materials which contain or have been in contact with animal by-products. Tests were carried out on food waste, slaughterhouse waste, animal blood, cattle slurry, potato waste, card packaging and the organic fraction of municipal solid waste (OFMSW); pasteurisation at 70 °C for 1 h was applied. Pasteurisation had increased the methane yields of blood (+15%) and potato waste (+12%) only, which both had a low content of structural carbohydrates (hemi-cellulose and cellulose) but a particularly high content of either non-structural carbohydrates such as starch (potato waste) or proteins (blood). With food waste, card packaging and cattle slurry, pasteurisation had no observable impact on the methane yield. Slaughterhouse waste and OFMSW yielded less methane after p... [more]
Hydroxypropyl Methylcellulose-Based Hydrogel Copolymeric for Controlled Delivery of Galantamine Hydrobromide in Dementia
Sidra Bashir, Nadiah Zafar, Noureddine Lebaz, Asif Mahmood, Abdelhamid Elaissari
May 11, 2021 (v1)
Subject: Biosystems
Keywords: dementia, galantamine hydrobromide (GH), HPMC, hydrogel, methylene bisacrylamide, pectin
The study aims to prepare a smart copolymeric for controlled delivery of Galantamine hydrobromide. The synthesis of the hydrogel was executed through free radical polymerization using HPMC (Hydroxypropyl methylcellulose) and pectin as polymers and acrylic acid as monomer. Cross-linking was performed by methylene bisacrylamide (MBA). HPMC-pectin-co-acrylic acid hydrogel was loaded with Galantamine hydrobromide (antidementia drug) as a model drug for treatment of Alzheimer based dementia. Formulated hydrogels (SN1−SN9) were characterized for Fourier transform-infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction, and energy dispersive X-ray. Drug loading efficiency, gel fraction, measurements of porosity, and tensile strength were reported. Swelling and release studies were performed at pH 1.2 and 7.4. Drug liberation mechanism was evaluated by applying different release kinetic models. Galantamine hydrobromide was released from prepared... [more]
Bacterial Toxicity Testing: Modification and Evaluation of the Luminescent Bacteria Test and the Respiration Inhibition Test
Uwe Strotmann, Daniel Pastor Flores, Odorico Konrad, Cornelia Gendig
May 11, 2021 (v1)
Subject: Biosystems
Keywords: activated sludge, bacterial toxicity, chlorinated phenols, Cr(VI) and Zn(II) cations, long-term toxicity, luminescent bacteria, respiration inhibition
The activated sludge respiration inhibition test and the luminescent bacteria test with Vibrio fischeri are important bacterial test systems for evaluation of the toxicity of chemical compounds. These test systems were further optimized to result in better handling, reliability and sensitivity. Concerning the Vibrio fischeri test, media components such as yeast extract and bivalent cation concentrations like Ca2+ and Mg2+ were optimized. The cultivation, storage conditions and reactivation process of the stored bacteria were also improved, which enabled simpler handling and led to good reproducibility. Additionally, the respiration inhibition test with a prolonged incubation time was further analyzed using different chlorinated phenols as reference compounds. It could be stated that a longer incubation period significantly improved the sensitivity of the test system.
The Influence of Particle Size and Crystallinity of Plant Materials on the Diffusion Constant for Model Extraction
Igor Lomovskiy, Liudmila Makeeva, Ekaterina Podgorbunskikh, Oleg Lomovsky
May 11, 2021 (v1)
Keywords: cellulose crystallinity, diffusion constant, diffusion fluxes, kinetic of extraction, mechanical treatment, resveratrol
Adsorbed polyphenolic compound (resveratrol) to a wheat straw matrix was considered as a model system for studying the influence of particle sizes and crystallinity of cell wall cellulose on the extraction process from the matrix of plant material. The morphology of wheat straw particles was studied by scanning electron microscopy and changes in the crystal structure of cellulose were determined using X-ray diffraction. The kinetics of resveratrol extraction were studied using high-performance liquid chromatography (HPLC). The diffusion constants were determined for particles of different sizes and particles having the same size but varying in the degree of disordering of cellulose, the main component of cell walls. The applicability of the Axelrud equation for calculating the mass transfer constants for plant objects with a complex internal structure was shown. Comparison of the particle sizes, the degree of crystallinity, and the calculated mass transfer constant makes it possible to... [more]
Separation of Gallium(III) and Indium(III) by Solvent Extraction with Ionic Liquids from Hydrochloric Acid Solution
Si Jeong Song, Minh Nhan Le, Man Seung Lee
May 11, 2021 (v1)
Subject: Materials
Keywords: gallium, hydrochloric acid, indium, ionic liquids, solvent extraction
The manufacture of semiconductor materials containing gallium and indium requires the separation of these metals owing to their coexistence in the resources of these materials. In this work, solvent extraction of In(III) and Ga(III) from a hydrochloric acid solution by ionic liquids (ILs) was investigated to separate them. The ILs were synthesized by reacting organophosphorus acids (Cyanex 272, PC88A and D2EHPA) and Aliquat 336 (ALi-CY, ALi-PC, and ALi-D2). In(III) was selectively extracted over Ga(III) by the ILs in the range of initial pH from 0.1 to 2.0. The equilibrium pH was always higher than the initial pH because of the coextraction of hydrogen ions. The highest separation factor between In(III) and Ga(III) was 87, which was obtained by ALi-PC at an initial pH of 1.0. Stripping of the loaded ALi-PC with hydrochloric and sulfuric acid led to selective stripping of In(III) over Ga(III). Scrubbing of the loaded ALi-PC with pure In(III) solution was not effective in removing the sm... [more]
Room Temperature Ferroelastic Creep Behavior of Porous (La0.6Sr0.4)0.95Co0.2Fe0.8O3-δ
Barbara Arnauda, Ali Akbari-Fakhrabadi, Nina Orlovskaya, Viviana Meruane, Wakako Araki
May 4, 2021 (v1)
Subject: Materials
Keywords: creep, ferroelasticity, LSCF, porosity
The time-dependent deformation of porous (La0.6Sr0.4)0.95Co0.2Fe0.8O3-δ (LSCF) under constant uniaxial compressive stress at room temperature has been studied. Both axial and lateral stress−strain deformation curves clearly show the non-linear ferroelastic behavior of LSCF perovskite during compression. The ferroelastic characteristics of deformation curves such as coercive stress and apparent loading moduli decrease when the porosity of the samples increases. Ferroelastic creep deformations at applied stresses of 25 and 50 MPa demonstrate that stress and porosity are influencing factors on creep deformation, which increases with increasing stress and porosity. A negative creep or axial expansion and lateral contraction were observed in the sample with 35% porosity under 50-MPa constant compression stress.
Influence of Fermented Diets on In Vitro Survival Rate of Some Artificially Inoculated Pathogens—A Preliminary Study
Sebastian Bunte, Birgit Keller, Bussarakam Chuppava, Josef Kamphues, Christian Visscher, Amr Abd El-Wahab
May 4, 2021 (v1)
Subject: Biosystems
Keywords: in vitro fermentation, liquid feed, pathogens
Improving the hygienic status of feed ingredients by biotechnological processes as fermentation is of the greatest concern. This preliminary study aimed to investigate whether there are relevant effects of fermented liquid feed (FLF) on the survival of potential pathogens in vitro. The feed (fresh basis) consisted of 50% rye, 30% rapeseed extracted meal, 10% barley and 10% wheat. Glass bottles were filled about 14.1 g water (38 °C) containing the diluted starter culture and feed (8.81 g). Fermentation led to high levels of lactate (5−7% of dry matter), low pH values (<4.0) and low levels of acetic acid (<1% of dry matter) in the FLF. The survival rate of pathogens added, such as Salmonella enterica serovar Typhimurium, Escherichia coli and Clostridium perfringens after 6 h of controlled fermentation, was significantly reduced (<2 log10 CFU/g). The counts of Candida krusei in FLF at 3 h and 6 h post inoculation remained almost unchanged regardless of the incubation time. Even a... [more]
Tributary Channel Width Effect on the Flow Behavior in Trapezoidal and Rectangular Channel Confluences
Aliasghar Azma, Yongxiang Zhang
May 4, 2021 (v1)
Keywords: channel confluence, flow structure, the separation zone
Channel confluences happen commonly in water transport networks and natural rivers. Utilizing a 3D CFD code, a series of numerical simulations were performed using a large eddy simulation turbulence model to investigate the effect of the variations in tributary channel width and the transverse geometrical shape of the main channel on the flow parameters and vertical structure in a T-shape confluence. The code was calibrated using the experimental data from the literature. Flow parameters were considered in ratios of tributary width to the main channel width in trapezoidal and rectangular channels. Results indicate that decreasing the width ratio of the tributary channel to the main channel significantly affects the flow structure in the confluence. Generally, it increases the width and length of the main recirculation zone. It also increases the maximum velocity near the bed, especially in cases with a trapezoidal shape. Besides, it highly affects the structure and formation of the rec... [more]
Magnetite and Hematite in Advanced Oxidation Processes Application for Cosmetic Wastewater Treatment
Piotr Marcinowski, Dominika Bury, Monika Krupa, Dominika Ścieżyńska, Prasanth Prabhu, Jan Bogacki
May 4, 2021 (v1)
Subject: Materials
Keywords: advanced oxidation processes, hematite, industrial wastewater, magnetite, zero valent iron
Wastewater from a cosmetic factory, with an initial total organic carbon (TOC) of 146.4 mg/L, was treated with Fe2O3/Fe0/H2O2, Fe3O4/Fe0/H2O2, light/Fe2O3/Fe0/H2O2, and light/Fe3O4/Fe0/H2O2 processes. The light-supported processes were more effective than the lightless processes. The fastest TOC removal was observed during the first 15 min of the process. Out of the four tested kinetic models, the best fit was obtained for the modified second-order reaction with respect to the TOC value. The best treatment efficiency was obtained for the light/Fe3O4/Fe0/H2O2 process with 250/750 mg/L Fe3O4/Fe0 reagent doses, a 1:1 hydrogen peroxide to Chemical Oxygen Demand (H2O2/COD) mass ratio, and a 120 min process time. These conditions allowed 75.7% TOC removal to a final TOC of 35.52 mg/L and 90.5% total nitrogen removal to a final content of 4.9 mg/L. The five-day Biochemical Oxygen Demand to Chemical Oxygen Demand (BOD5/COD) ratio was increased slightly from 0.124 to 0.161. Application of Head... [more]
Comparison of Solar Collector Testing Methods—Theory and Practice
Paweł Obstawski, Tomasz Bakoń, Dariusz Czekalski
May 4, 2021 (v1)
Keywords: construction of solar thermal collector, efficiency characteristics, equivalent thermal network, parametric identification, thermo-electric analogy, time constant
One of the most important problems of operating solar heating systems involves variable efficiency depending on operating conditions. This problem is more pronounced in hybrid energy systems, where a solar installation cooperates with other segments based on conventional carriers of energy or renewable sources of energy. The operating cost of each segment of a hybrid system depends mainly on the resulting efficiency of solar installation. For over 40 years, the procedures of testing solar collectors have been undergoing development, testing, comparison and verification in order to create a procedure that would allow determining the thermal behavior of a solar collector without performing expensive and complicated experimental tests, usually based on the steady state condition. The proper determination of the static and dynamic properties of a solar collector is of key significance, as they constitute a basis for the design of a solar heating installation, as well as a control system. I... [more]
Bioactive and Topographically-Modified Electrospun Membranes for the Creation of New Bone Regeneration Models
Dina Abdelmoneim, Ghsaq M. Alhamdani, Thomas E. Paterson, Martin E. Santocildes Romero, Beatriz J. C. Monteiro, Paul V. Hatton, Ilida Ortega Asencio
May 4, 2021 (v1)
Subject: Biosystems
Keywords: artificial microenvironment, bioglass, bone regeneration, ECM proteins, electrospun membrane
Bone injuries that arise from trauma, cancer treatment, or infection are a major and growing global challenge. An increasingly ageing population plays a key role in this, since a growing number of fractures are due to diseases such as osteoporosis, which place a burden on healthcare systems. Current reparative strategies do not sufficiently consider cell-substrate interactions that are found in healthy tissues; therefore, the need for more complex models is clear. The creation of in vitro defined 3D microenvironments is an emerging topographically-orientated approach that provides opportunities to apply knowledge of cell migration and differentiation mechanisms to the creation of new cell substrates. Moreover, introducing biofunctional agents within in vitro models for bone regeneration has allowed, to a certain degree, the control of cell fate towards osteogenic pathways. In this research, we applied three methods for functionalizing spatially-confined electrospun artificial microenvi... [more]
Suzuki−Miyaura Reactions of (4-bromophenyl)-4,6-dichloropyrimidine through Commercially Available Palladium Catalyst: Synthesis, Optimization and Their Structural Aspects Identification through Computational Studies
Ayesha Malik, Nasir Rasool, Iram Kanwal, Muhammad Ali Hashmi, Ameer Fawad Zahoor, Gulraiz Ahmad, Ataf Ali Altaf, Syed Adnan Ali Shah, Sadia Sultan, Zainul Amiruddin Zakaria
May 4, 2021 (v1)
Keywords: DFT, FMO, Pd catalyst, reactivity descriptors, Suzuki–Miyaura
5-(4-bromophenyl)-4,6-dichloropyrimidine was arylated with several aryl/heteroaryl boronic acids via the Suzuki cross-coupling reaction by using Pd(0) catalyst to yield novel pyrimidine analogs (3a-h). It was optimized so that good yields were obtained when 5 mol % Pd(PPh3)4 was used along with K3PO4 and 1,4-Dioxane. Electron-rich boronic acids were succeeded to produce good yields of products. Density functional theory (DFT) calculations were also applied on these new compounds to analyze their reactivity descriptors and electronic and structural relationship. According to DFT studies, compound 3f is the most reactive one, while 3g is the most stable one. As per DFT studies, the hyperpolarizability (β) values of these compounds do not show them as very good non-linear optical (NLO) materials. Compound 3f has the highest β value among all the compounds under study but still it is not high enough to render it a potent NLO material.
Monitoring, Diffusion and Source Speculation Model of Urban Soil Pollution
Zhichao Li, Wanchun Lu, Jilin Huang
May 4, 2021 (v1)
Keywords: air subsidence model, convective dispersion model, kriging interpolation, pollution of soil heavy metals
The rapid industrialization of cities has brought many challenges to the environment and resources. Industrial wastes, automobile exhaust, coal combustion soot and other pollutants accumulate in urban soil, and the characteristics of urban soil are changed, causing many pollutants to accumulate in the urban soil environment. Heavy metals are toxic and harmful pollutants existing in soil that cannot be biodegraded or thermally degraded; thus, heavy metals pose a threat to environmental quality and humans. To solve the environmental pollution of soil heavy metals, we utilize kriging interpolation to determine the geological distribution of the environmental pollution of metal elements and analyze the main causes of soil heavy metal pollution. Next, the propagation characteristics and diffusion process of heavy metal pollutants are thoroughly analyzed; in addition, an improved one-dimensional convective dispersion model and an improved air subsidence model are established, and real urban... [more]
Effect of Rotor Spacing and Duct Diffusion Angle on the Aerodynamic Performances of a Counter-Rotating Ducted Fan in Hover Mode
Woo-Yul Kim, Santhosh Senguttuvan, Sung-Min Kim
May 4, 2021 (v1)
Subject: Other
Keywords: figure of merit, frozen rotor, power coefficient, thrust coefficient, UAV
The aerodynamic performance of a counter-rotating ducted fan in hover mode is numerically analyzed for different rotor spacings and duct diffusion angles. The design of the counter-rotating fan is inspired by a custom-designed single rotor ducted fan used in a previous study. The numerical model to predict the aerodynamic performance of the counter-rotating ducted fan is developed by adopting the frozen rotor approach for steady-state incompressible flow conditions. The relative angle between the front and the rear rotor is examined due to the usage of the frozen rotor model. The results show that the variation of thrust for the different relative angles is extremely low. The aerodynamic performances are evaluated by comparing the thrust, thrust coefficient, power coefficient, and figure of merit (FOM). The thrust, thrust coefficient, and FOM slightly increase with increasing rotor spacing up to 200 mm, regardless of the duct diffusion angle, and reduce on further increase in the rotor... [more]
Linear Analysis of a Continuous Crystallization Process for Enantiomer Separation
Michael Mangold, Nadiia Huskova, Jonathan Gänsch, Andreas Seidel-Morgenstern
May 4, 2021 (v1)
Keywords: crystallization, distributed system, method of characteristics, population balance, process control
Continuous preferential crystallization is an innovative approach to the separation of chiral substances. The process considered in this work takes place in a gently agitated fluidized bed located in a tubular crystallizer. The feasibility of the process has been shown in previous work, but it also turned out that choosing suitable operation conditions is quite delicate. Hence, a model based process design is desirable. Existing models of the process are rather complicated and require long computational times. In this work, a simple linear dynamic model is suggested, which captures the main properties of the process. The model is distributed in space and in a property coordinate. Using the method of characteristics, a semi-analytical solution of the linear model is derived. As a challenge to the solution, there is a recycle loop in the process that causes a feedback and couples the boundary conditions at different boundaries of the computational domain. In order to deal with this, a nu... [more]
Dynamic Characteristics of Gear Coupling and Rotor System in Transmission Process Considering Misalignment and Tooth Contact Analysis
Wei Fan, Hong Lu, Yongquan Zhang, Xiangang Su
May 4, 2021 (v1)
Keywords: dynamic characteristics, finite element analysis, gear coupling-rotor system, low-frequency vibration, misalignment
The dynamic vibration of the gear coupling-rotor system (GCRS) caused by misalignment is an important factor of low frequency vibration and noise radiation of the naval marine. The axial misalignment of gear coupling is inevitable owing to mass eccentricity, and is unconstrained in axial direction at high-speed operation. Therefore, the dynamic model of GCRS is proposed, considering gear-coupling misalignment and contact force in this paper. The whole motion differential equation of GCRS is established based on the finite element method. Moreover, the numerical calculation method of meshing force, considering the uniform distribution load on contact surface, is presented, and the mathematical predictive time−frequency characteristics are analyzed by the Newmark stepwise integral approach. Finally, a reduced-scale application of the propulsion shaft system is utilized to validate the effectiveness of the proposed dynamic model. For the sensibility to low-frequency vibration, the natural... [more]
Dead-Man Behavior in the Blast Furnace Hearth—A Brief Review
Lei Shao, Qilin Xiao, Chengbo Zhang, Zongshu Zou, Henrik Saxén
May 4, 2021 (v1)
Subject: Other
Keywords: blast furnace hearth, dead man, hearth drainage, iron and slag flow, lining wear
The blast furnace campaign length is today usually restricted by the hearth life, which is strongly related to the drainage and behavior of the coke bed in the hearth, usually referred to as the dead man. Because the hearth is inaccessible and the conditions are complex, knowledge and understanding of the state of the dead man are still limited compared to other parts of the blast furnace process. Since a number of publications have studied different aspects of the dead man in the literature, the purpose of the current review is to compile the findings and knowledge in a comprehensive document. We mainly focus on contributions with respect to the dead man state, and those assessing its influence on the hearth performance in terms of liquid flow patterns, lining wear and drainage behavior. A set of common modeling approaches in this specific furnace area is also briefly presented. The aim of the review is also to deepen the understanding and stimulate further research on open questions... [more]
Coupled Simulation of a Vacuum Creation System and a Rectification Column Block
Eduard Osipov, Eduard Telyakov, Sergey Ponikarov
May 4, 2021 (v1)
Keywords: liquid ring vacuum pump, rectification, steam ejection pumps, universal modeling program, vacuum creating system
The purpose of this study was the coupling simulation of the vacuum block of the ethanolamine mixture separation unit to determine the optimal layout of the vacuum creation system. For this, a computational model of the vacuum unit, which was identified by comparing the computational data with the data of an industrial study of vacuum rectification columns, was synthesized in the Unisim Design R461 software package. To determine the required load on the vacuum system, a numerical experiment was carried out, during which it was discovered that the load on the system would be 9600 m3/h. It was proposed to replace individual column vacuum pumps with a single vacuum-generating system (VGS) based on a liquid ring vacuum pump (LRVP). When defining the layout, two possible schemes were considered, the models of which were created in Unisim Design R461. The system layout was determined by matching the characteristics of the system elements with the characteristics of the vacuum columns. A tech... [more]
Pressurized Liquid Extraction of Cannabinoids from Hemp Processing Residues: Evaluation of the Influencing Variables
Sebastián Serna-Loaiza, Johannes Adamcyk, Stefan Beisl, Christoph Kornpointner, Heidi Halbwirth, Anton Friedl
May 4, 2021 (v1)
Keywords: biorefineries, cannabidiol, cannabinoids, hemp residues, Renewable and Sustainable Energy
Cannabinoids have gained significant interest as they may have pharmaceutical and nutritional applications to treat various diseases (sclerosis, glaucoma, and epilepsy, among others). Hemp (Cannabis sativa L.) has been studied recently as a source of cannabinoids, given the low concentration of tetrahydrocannabinol and comparatively high concentration of cannabidiol. Most of the plant’s fractions are used (blossoms, stem, and seeds), but the processing of the blossom leaves a residue, threshing residues, which could still be used to extract cannabinoids, aiming for an integral usage of the plant. Different technologies have been applied for cannabinoid extraction. Among these, pressurized liquid extraction (PLE) stands out due to the ease of application and efficiency. This work evaluates the influence of temperature, pressure, extraction time, and the number of cycles for the PLE of cannabinoids from hemp threshing residues using ethanol. Results show that low pressures, 100 °C, and 6... [more]
Processing Methods Used in the Fabrication of Macrostructures Containing 1D Carbon Nanomaterials for Catalysis
João Restivo, Olívia Salomé Gonçalves Pinto Soares, Manuel Fernando Ribeiro Pereira
May 4, 2021 (v1)
Subject: Materials
Keywords: 1D carbon nanomaterials, carbon nanofibers, Catalysis, catalyst preparation, nanocatalysts, nanostructured carbon, structured catalysts
A large number of methodologies for fabrication of 1D carbon nanomaterials have been developed in the past few years and are extensively described in the literature. However, for many applications, and in particular in catalysis, a translation of the materials to a macro-structured form is often required towards their use in practical operation conditions. This review intends to describe the available methods currently used for fabrication of such macro-structures, either already applied or with potential for application in the fabrication of macro-structured catalysts containing 1D carbon nanomaterials. A review of the processing methods used in the fabrication of macrostructures containing 1D sp2 hybridized carbon nanomaterials is presented. The carbon nanomaterials here discussed include single- and multi-walled carbon nanotubes, and several types of carbon nanofibers (fishbone, platelet, stacked cup, etc.). As the processing methods used in the fabrication of the macrostructures ar... [more]
A Closed-Loop Optimized System with CFD Data for Liquid Maldistribution Model
Wei Zhang, Liyi Li, Baoping Zhang, Xin Xu, Jian Zhai, Junwen Wang
May 4, 2021 (v1)
Keywords: computational fluid dynamic (CFD) simulation, gas-liquid distributor, liquid maldistribution model, particle swarm optimization (PSO), response surface method (RSM), support vector regression (SVR)
For the simulation of a trickle-bed reactor (TBR) in coal and oil refining, modeling the liquid maldistribution of the gas-liquid distributor incurs enormous pre-processing work and bears a huge computational cost. A closed-loop optimized system with computational fluid dynamic (CFD) data is therefore proposed for the first time in this paper. A fast prediction model based on support vector regression (SVR) is developed to simplify the modeling of the liquid flow rate in TBRs. The model uses CFD simulation results to determine an optimized set of structural parameters for the gas-liquid distributor in TBRs. In order to obtain an accurate SVR model quickly, the particle swarm optimization (PSO) algorithm is employed to optimize the SVR parameters. Then, the structural parameters corresponding to the minimum liquid maldistribution factor are calculated using the response surface methodology (RSM) based on the hybrid PSO-SVR model. The CFD validation results show a good agreement with the... [more]
The Advantages of Polymeric Hydrogels in Calcineurin Inhibitor Delivery
Claudia Sandoval-Yañez, Leslie Escobar, Cristián A. Amador
May 4, 2021 (v1)
Subject: Biosystems
Keywords: calcineurin inhibitors, cyclosporine, drug delivery, polymeric hydrogels, tacrolimus
In recent years, polymeric hydrogels (PolyHy) have been extensively explored for their applications in biomedicine as biosensors, in tissue engineering, diagnostic processes, and drug release. The physical and chemical properties of PolyHy indicate their potential use in regulating drug delivery. Calcineurin inhibitors, particularly cyclosporine (CsA) and tacrolimus (TAC), are two important immunosuppressor drugs prescribed upon solid organ transplants. Although these drugs have been used since the 1970s to significantly increase the survival of transplanted organs, there are concerns regarding their undesirable side effects, primarily due to their highly variable concentrations. In fact, calcineurin inhibitors lead to acute and chronic toxicities that primarily cause adverse effects such as hypertension and nephrotoxicity. It is suggested from the evidence that the encapsulation of calcineurin inhibitors into PolyHy based on polysaccharides, specifically alginate (Alg), offers effecti... [more]
Performing an Indirect Coupled Numerical Simulation for Capacitor Discharge Welding of Aluminium Components
Johannes Koal, Martin Baumgarten, Stefan Heilmann, Jörg Zschetzsche, Uwe Füssel
May 4, 2021 (v1)
Keywords: aluminium alloy, capacitor discharge welding, contact resistance, finite element method, indirect coupling, multiphysics model, numerical simulation, projection welding
Capacitor discharge welding (CDW) for projection welding provides very high current pulses in extremely short welding times. This requires a quick follow up behaviour of the electrodes during the softening of the projection. The possibilities of experimental process investigations are strongly limited because of the covered contact zone and short process times. The Finite Element Method (FEM) allows highly resoluted analyses in time and space and is therefore a suitable tool for process characterization and optimization. To utilize this mean of optimization, an indirect multiphysical numerical model has been developed in Ansys Mechanical APDL. This model couples the physical environments of thermal−electric with structural analysis. It can master the complexity of large deformations, short current rise times and high temperature gradients. A typical ring projection has been chosen as the joining task. The selected aluminium alloys are EN-AW-6082 (ring projection) and EN-AW-5083 (sheet... [more]
Numerical Investigation of the Effect of Incorporated Guide Vane Length with SCC Piston for High-Viscosity Fuel Applications
Mohd Fadzli Hamid, Mohamad Yusof Idroas, Mazlan Mohamed, Shukriwani Sa'ad, Teoh Yew Heng, Sharzali Che Mat, Muhamad Azman Miskam, Zainal Alimuddin Zainal Alauddin, Muhammad Khalil Abdullah
May 4, 2021 (v1)
Keywords: Alternative Fuels, Biofuels, engine modelling, guide vane, piston
Compression ignition (CI) engines that run on high-viscosity fuels (HVF) like emulsified biofuels generally demonstrate poor engine performance. An engine with a consistently low performance, in the long run, will have a negative effect on its lifespan. Poor combustion in engines occurs mainly due to the production of less volatile, less flammable, denser, and heavier molecules of HVF during injection. This paper proposes a guide vane design (GVD) to be installed at the intake manifold, which is incorporated with a shallow depth re-entrance combustion chamber (SCC) piston. This minor modification will be advantageous in improving the evaporation, diffusion, and combustion processes in the engine to further enhance its performance. The CAD models of the GVD and SCC piston were designed using SolidWorks 2018 while the flow run analysis of the cold flow CI engine was conducted using ANSYS Fluent Version 15. In this study, five designs of the GVD with varying lengths of the vanes from 0.6D... [more]
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