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Records Added in April 2021
Records added in April 2021
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Showing records 1 to 25 of 175. [First] Page: 1 2 3 4 5 Last
Mathematical Model of COVID-19 Transmission Dynamics in South Korea: The Impacts of Travel Restrictions, Social Distancing, and Early Detection
Byul Nim Kim, Eunjung Kim, Sunmi Lee, Chunyoung Oh
April 30, 2021 (v1)
Keywords: basic reproduction number, COVID-19 transmission dynamics in South Korea, cumulative incidence, early diagnostic interventions, mobility data, social distancing, travel restrictions, two-patch mathematical model
The novel coronavirus disease (COVID-19) poses a severe threat to public health officials all around the world. The early COVID-19 outbreak in South Korea displayed significant spatial heterogeneity. The number of confirmed cases increased rapidly in the Daegu and Gyeongbuk (epicenter), whereas the spread was much slower in the rest of Korea. A two-patch mathematical model with a mobility matrix is developed to capture this significant spatial heterogeneity of COVID-19 outbreaks from 18 February to 24 March 2020. The mobility matrix is taken from the movement data provided by the Korea Transport Institute (KOTI). Some of the essential patch-specific parameters are estimated through cumulative confirmed cases, including the transmission rates and the basic reproduction numbers (local and global). Our simulations show that travel restrictions between the epicenter and the rest of Korea effectively prevented massive outbreaks in the rest of Korea. Furthermore, we explore the effectiveness... [more]
CFD Hydrodynamics Investigations for Optimum Biomass Gasifier Design
Emanuele Fanelli
April 30, 2021 (v1)
Keywords: biomass gasification, clean energy production, cold model testing, fluid dynamics investigation, fluidized bed modeling
Biomass gasification is nowadays considered a viable option for clean energy production. Furthermore, still more efforts need to be spent to make this technology fully available at commercial scale. Drawbacks that greatly limit the full-time plant availability—and so its economically feasibility—mainly concerns syngas purification by contaminants such as tars. Different technological approaches were investigated over last two decades with the aim to increase both the plant availability and the overall efficiency by keeping, at the same time, CAPEX and OPEX low. Among technologies, fluidized beds are surely the most promising architectures for power production at thermal scale above 1 MWth. Gasifier can be surely considered the key component of the whole power plant and its proper design, the main engineering effort. This process involves different engineering aspects: thermo-structural, heat, and mass transfer, and chemical and fluid-dynamic concerns being the most important. In this s... [more]
A Review on the Control Parameters of Natural Convection in Different Shaped Cavities with and without Nanofluid
Sara Rostami, Saeed Aghakhani, Ahmad Hajatzadeh Pordanjani, Masoud Afrand, Goshtasp Cheraghian, Hakan F. Oztop, Mostafa Safdari Shadloo
April 30, 2021 (v1)
Keywords: cavity, nanofluid, natural convection, non-Newtonian, numerical study
Natural convection in cavities is an interesting subject for many researchers. Especially, in recent years, the number of articles written in this regard has grown enormously. This work provides a review of recent natural convection studies. At first, experimental studies were reviewed and, then, numerical studies were examined. Then, the articles were classified based on effective parameters. In each section, numerical studies were examined the parameters added to the cavity such as magnetic forces, fin, porous media and cavity angles. Moreover, studies on non-rectangular cavities were investigated. Free convection in enclosures depends more on the fluid velocity relative to the forced convection, leading to the opposite effect of some parameters that should essentially enhance rate of heat transfer. Nanoparticle addition, magnetic fields, fins, and porous media may increase forced convection. However, they can reduce free convection due to the reduction in fluid velocity. Thus, these... [more]
Control-Oriented Modeling and Experimental Validation of a Deoiling Hydrocyclone System
Mads V. Bram, Stefan Jespersen, Dennis S. Hansen, Zhenyu Yang
April 30, 2021 (v1)
Keywords: droplet trajectories, experimental validation, hydrocyclone, Modelling, oil-in-water measurements, separation efficiency
As the treated water from offshore oil and gas production is discharged to the surrounding sea, there is an incentive to improve the performance of the offshore produced water treatment, to reduce the environmental pollutants to the sea. Regulations determine both the maximum allowed oil concentration and the total annual quantity. It is reasonable to assume that when better separation equipment or methods are developed, the regulation will become more strict, and force other producers to follow the trend towards zero harmful discharge. This paper develops and validates a hydrocyclone model to be used as a test-bed for improved control designs. The modeling methodology uses a combination of first-principles to define model structure and data-driven parameter identification. To evaluate and validate the separation performance, real-time fluorescence-based oil-in-water (OiW) concentration monitors, with dual redundancy, are installed and used on sidestreams of a modified pilot plant. The... [more]
Electrochemical Hydrogen Production Using Separated-Gas Cells for Soybean Oil Hydrogenation
Jorge Eduardo Esquerre Verastegui, Marco Antonio Zamora Antuñano, Juvenal Rodríguez Resendiz, Raul García García, Pedro Jacinto Paramo Kañetas, Daniel Larrañaga Ordaz
April 30, 2021 (v1)
Keywords: electrochemical cell, electrochemistry, electrolysis, flow cell, hydrogenation, modeling research
Although hydrogen is the most abundant element in the universe, it is not possible to find it in its purest state in nature. In this study, two-stage experimentation was carried out. The first stage was hydrogen production. The second stage was an electrochemical process to hydrogenate soybean oil in a PEM fuel cell. In the fist stage a Zirfon Perl UTP 500 membrane was used in an alkaline hydrolizer of separated gas to produce hydrogen, achieving 9.6 L/min compared with 5.1 L/min, the maximum obtained using a conventional membrane. The hydrogen obtained was used in the second stage to feed the fuel cell hydrogenating the soybean oil. Hydrogenated soybean oil showed a substantial diminished iodine index from 131 to 54.85, which represents a percentage of 58.13. This happens when applying a voltage of 90 mV for 240 min, constant temperature of 50 °C and one atm. This result was obtained by depositing 1 mg of Pt/cm 2 in the cathode of the fuel cell. This system represents a viable... [more]
A Two-Patch Mathematical Model for Temperature-Dependent Dengue Transmission Dynamics
Jung Eun Kim, Yongin Choi, James Slghee Kim, Sunmi Lee, Chang Hyeong Lee
April 30, 2021 (v1)
Keywords: climate change, control strategies, dengue transmission, patch model, temperature-dependent parameters
Dengue fever has been a threat to public health not only in tropical regions but non-tropical regions due to recent climate change. Motivated by a recent dengue outbreak in Japan, we develop a two-patch model for dengue transmission associated with temperature-dependent parameters. The two patches represent a park area where mosquitoes prevail and a residential area where people live. Based on climate change scenarios, we investigate the dengue transmission dynamics between the patches. We employ an optimal control method to implement proper control measures in the two-patch model. We find that blockage between two patches for a short-term period is effective in a certain degree for the disease control, but to obtain a significant control effect of the disease, a long-term blockage should be implemented. Moreover, the control strategies such as vector control and transmission control are very effective, if they are implemented right before the summer outbreak. We also investigate the c... [more]
A Joint Optimization Strategy of Coverage Planning and Energy Scheduling for Wireless Rechargeable Sensor Networks
Cheng Gong, Chao Guo, Haitao Xu, Chengcheng Zhou, Xiaotao Yuan
April 30, 2021 (v1)
Keywords: coverage optimization, Particle Swarm Optimization, queuing game, virtual force, wireless rechargeable sensor network
Wireless Sensor Networks (WSNs) have the characteristics of large-scale deployment, flexible networking, and many applications. They are important parts of wireless communication networks. However, due to limited energy supply, the development of WSNs is greatly restricted. Wireless rechargeable sensor networks (WRSNs) transform the distributed energy around the environment into usable electricity through energy collection technology. In this work, a two-phase scheme is proposed to improve the energy management efficiency for WRSNs. In the first phase, we designed an annulus virtual force based particle swarm optimization (AVFPSO) algorithm for area coverage. It adopts the multi-parameter joint optimization method to improve the efficiency of the algorithm. In the second phase, a queuing game-based energy supply (QGES) algorithm was designed. It converts energy supply and consumption into network service. By solving the game equilibrium of the model, the optimal energy distribution str... [more]
Digital Twin for Lyophilization by Process Modeling in Manufacturing of Biologics
Leon S. Klepzig, Alex Juckers, Petra Knerr, Frank Harms, Jochen Strube
April 30, 2021 (v1)
Keywords: biologics, digital twin, lyophilization, manufacturing, model validation, Process Intensification, quality-by-design
Lyophilization stabilizes formulated biologics for storage, transport and application to patients. In process design and operation it is the link between downstream processing and with final formulation to fill and finish. Recent activities in Quality by Design (QbD) have resulted in approaches by regulatory authorities and the need to include Process Analytical Technology (PAT) tools. An approach is outlined to validate a predictive physical-chemical (rigorous) lyophilization process model to act quantitatively as a digital twin in order to allow accelerated process design by modeling and to further-on develop autonomous process optimization and control towards real time release testing. Antibody manufacturing is chosen as a typical example for actual biologics needs. Literature is reviewed and the presented procedure is exemplified to quantitatively and consistently validate the physical-chemical process model with aid of an experimental statistical DOE (design of experiments) in pil... [more]
A Novel Consensus Fuzzy K-Modes Clustering Using Coupling DNA-Chain-Hypergraph P System for Categorical Data
Zhenni Jiang, Xiyu Liu
April 30, 2021 (v1)
Keywords: chain P system, consensus clustering, fuzzy k-modes algorithm, hypergraph structure
In this paper, a data clustering method named consensus fuzzy k-modes clustering is proposed to improve the performance of the clustering for the categorical data. At the same time, the coupling DNA-chain-hypergraph P system is constructed to realize the process of the clustering. This P system can prevent the clustering algorithm falling into the local optimum and realize the clustering process in implicit parallelism. The consensus fuzzy k-modes algorithm can combine the advantages of the fuzzy k-modes algorithm, weight fuzzy k-modes algorithm and genetic fuzzy k-modes algorithm. The fuzzy k-modes algorithm can realize the soft partition which is closer to reality, but treats all the variables equally. The weight fuzzy k-modes algorithm introduced the weight vector which strengthens the basic k-modes clustering by associating higher weights with features useful in analysis. These two methods are only improvements the k-modes algorithm itself. So, the genetic k-modes algorithm is prop... [more]
Biomass Pretreatment with the Szego Mill™ for Bioethanol and Biogas Production
Merlin Raud, Kaja Orupõld, Lisandra Rocha-Meneses, Vahur Rooni, Olev Träss, Timo Kikas
April 30, 2021 (v1)
Keywords: bioethanol, biogas, nitrogen assisted milling, Szego Mill™, wet milling
Results from an investigation of the mechanical size reduction with the Szego Mill™ as a pretreatment method for lignocellulosic biomass are presented. Pretreatment is a highly expensive and energy-consuming step in lignocellulosic biomass processing. Therefore, it is vital to study and optimize different pretreatment methods to find a most efficient production process. The biomass was milled with the Szego Mill™ using three different approaches: dry milling, wet milling and for the first time nitrogen assisted wet milling was tested. Bioethanol and biogas production were studied, but also fibre analysis and SEM (scanning electron microscope) analysis were carried out to characterize the effect of different milling approaches. In addition, two different process flows were used to evaluate the efficiency of downstream processing steps. The results show that pretreatment of barely straw with the Szego Mill™ enabled obtaining glucose concentrations of up to 7 g L−1 in the hydrolysis mixtu... [more]
Motor Fault Detection Using Wavelet Transform and Improved PSO-BP Neural Network
Chun-Yao Lee, Yi-Hsin Cheng
April 30, 2021 (v1)
Keywords: back propagation neural network, Fault Detection, induction motors, particle swarm optimization wavelet transform
This paper proposes a motor fault detection method based on wavelet transform (WT) and improved PSO-BP neural network which is combined with improved particle swarm optimization (PSO) and a back propagation (BP) neural network with linearly increasing inertia weight. First, this research used WT to analyze the current signals of the healthy motor, bearing damage motor, stator winding inter-turn short circuit motor, and broken rotor bar motor. Second, features after completing the signal analysis were extracted, and three types of classifiers were used to classify. The results show that the improved PSO-BP neural network can effectively detect the cause of failure. In addition, in order to simulate the actual operating environment of the motor, this study added white noise with signal noise ratios of 30 dB, 25 dB, and 20 dB to verify that this model has a better anti-noise ability.
High Cell Density Cultivation of Saccharomyces cerevisiae with Intensive Multiple Sequential Batches Together with a Novel Technique of Fed-Batch at Cell Level (FBC)
Kwanruthai Malairuang, Morakot Krajang, Jatuporn Sukna, Krongchan Rattanapradit, Saethawat Chamsart
April 30, 2021 (v1)
Subject: Biosystems
Keywords: bioreactor, cell cultivation, dextrin, fed-batch at cell level (FBC), high cell density cultivation (HCDC), intensive multiple sequential batch (IMSB), S. cerevisiae
High cell density cultivation (HCDC) is developed for the production of microbial biomasses and their products. They must be produced from high concentrations of substrate, e.g., glucose or sucrose. In batch culture, a high concentration of those sugars >40−50% (w/v) cannot efficiently be utilized because of a dissolved O2 limitation causing the Crabtree effect that produces toxic by-products, i.e., ethanol and/or acetate, that inhibit cell growth. To prevent this effect, the HCDC is conducted with the fed-batch strategies. However, it has many disadvantages, i.e., complicated operations. To overcome those problems, this study was designed to use a new, efficient C-source (carbon source) substrate, namely dextrin, an oligomer of glucose. It can be utilized by yeast at a very high concentration of ~100 g/L although using just batch cultivation. As it is gradually hydrolyzed to release glucose molecules and gradually assimilated into the cells as “fed-batch at the cell level” (FBC), it p... [more]
Insulin Release from NPH Insulin-Loaded Pluronic® F127 Hydrogel in the Presence of Simulated Tissue Enzyme Activity
Muhammad H. Sultan, Wael A. Mahdi, Young M. Kwon
April 30, 2021 (v1)
Subject: Biosystems
Keywords: drug release, insulin, protein delivery, thermosensitive polymers, tissue enzymes
Background: Despite the widespread use of newer basal insulins, Natural Protamine Hagedorn (NPH) insulin still represents a well-established basal formulation with its long history of use, featuring the native form of human insulin. However, NPH insulin exhibits an undesirable peak within hours after a single subcutaneous (s.c.) injection, which may lead to hypoglycemia followed by insufficient basal insulin delivery. This may be attributed to the s.c. enzyme activities degrading the protamine in NPH microcrystals. Methods: A thermogelling block copolymer Pluronic® F127 (PF127) was utilized as a protective carrier for NPH microcrystals and as a modulator for insulin release from NPH. NPH insulin-loaded PF127 gel was prepared with varying concentrations of the polymer (15−25%) under mild conditions. The formulations were characterized for their gelling temperature, morphology, gel erosion, and in vitro insulin release, with trypsin concentrations up to 5 U/mL. Results: Scanning electron... [more]
The Effects of Different Slurry Concentrations and Wire Speeds for Swinging and Non-Swinging Wire-Saw Machining
Yao-Yang Tsai, Yi-Chian Chen, Yunn-Shiuan Liao, Chia-Chin Hsieh, Chung-Chen Tsao, Chun-Yao Hsu
April 30, 2021 (v1)
Subject: Other
Keywords: material removal rate, slurry concentration, swinging, wire speed, wire-saw machining
Slurry concentration and wire speed affect the yield and machining quality of ceramics (Al2O3) that are produced using wire-saw machining (WSM). This study determines the effect of slurry concentration and wire speed on the material removal rate (MRR), the machined surface roughness (SR), the kerf width, the wire wear and the flatness for swinging and non-swinging WSM. The experiments show that swinging WSM results in a higher machining efficiency than non-swinging WSM. WSM with swinging also achieves a peak MRR at a medium slurry concentration (25 wt%) and a higher wire speed (5.6 m/s) using the cutting conditions for the experimental region. However, slurry concentration and wire speed have no significant effect on the machined SR, the kerf width, the wire wear or the flatness for WSM with swinging mode.
Effect of Short Blade Circumferential Position Arrangement on Gas-Liquid Two-Phase Flow Performance of Centrifugal Pump
Biaobiao Wang, Haoyang Zhang, Fanjie Deng, Chenguang Wang, Qiaorui Si
April 30, 2021 (v1)
Subject: Other
Keywords: blade circumferential offset, centrifugal pump, gas-liquid two-phase flow, splitter blades
In order to study the internal flow characteristics of centrifugal pumps with a split impeller under gas-liquid mixed transportation conditions, this paper conducted a steady calculation of the flow field in the centrifugal pump under the conditions of different inlet gas volume fractions based on the Eulerian-Eulerian heterogeneous flow model, using air and water as the working media and the Schiller Nauman model for the interphase resistance. This paper takes a low specific speed centrifugal pump as the research object, through the controlling variables, using the same pump body structure and pump body geometric parameters and setting three different arrangements of long and short blades (each plan uses the same long and short blades) to explore the influence of the short blade arrangement on the low specific speed centrifugal pump performance under a gas-liquid two-phase flow. The research results show that, under pure water conditions, the reasonable arrangement of the short blade... [more]
Efficient Simulation of Chromatographic Processes Using the Conservation Element/Solution Element Method
Valentin Plamenov Chernev, Alain Vande Wouwer, Achim Kienle
April 30, 2021 (v1)
Keywords: conservation element/solution element (CE/SE) method, method of lines (MOL), simulated moving bed (SMB) chromatography, Simulation, single-column chromatography
Chromatographic separation processes need efficient simulation methods, especially for nonlinear adsorption isotherms such as the Langmuir isotherms which imply the formation of concentration shocks. The focus of this paper is on the space−time conservation element/solution element (CE/SE) method. This is an explicit method for the solution of systems of partial differential equations. Numerical stability of this method is guaranteed when the Courant−Friedrichs−Lewy condition is satisfied. To investigate the accuracy and efficiency of this method, it is compared with the classical cell model, which corresponds to a first-order finite volume discretization using a method of lines approach (MOL). The evaluation is done for different models, including the ideal equilibrium model and a mass transfer model for different adsorption isotherms—including linear and nonlinear Langmuir isotherms—and for different chromatographic processes from single-column operation to more sophisticated simulat... [more]
The Brooks and Corey Capillary Pressure Model Revisited from Pore Network Simulations of Capillarity-Controlled Invasion Percolation Process
Xiang Lu, Abdolreza Kharaghani, Hadi Adloo, Evangelos Tsotsas
April 30, 2021 (v1)
Subject: Materials
Keywords: capillary pressure, network structure, pore network simulations, size distribution index, wetting phase residual saturation
Relating the macroscopic properties of porous media such as capillary pressure with saturation is an on-going problem in many fields, but examining their correlations with microstructural traits of the porous medium is a challenging task due to the heterogeneity of the solid matrix and the limitations of laboratory instruments. Considering a capillarity-controlled invasion percolation process, we examined the macroscopic properties as functions of matrix saturation and pore structure by applying the throat and pore network model. We obtained a relationship of the capillary pressure with the effective saturation from systematic pore network simulations. Then, we revisited and identified the microstructure parameters in the Brooks and Corey capillary pressure model. The wetting phase residual saturation is related to the ratio of standard deviation to the mean radius, the ratio of pore radius to the throat length, and pore connectivity. The size distribution index in the Brooks and Corey... [more]
Evolution and Physical Characteristics of a Raceway Based on a Transient Eulerian Multiphase Flow Model
Xing Peng, Jingsong Wang, Haibin Zuo, Qingguo Xue
April 30, 2021 (v1)
Keywords: Eulerian multiphase flow, flow pattern, raceway evolution, raceway size
In industrial processes, a semi-cavity area formed by airflow wherein the particles circulate is called a “raceway”. In a blast furnace, the role of the raceway is particularly important. To understand and predict the evolution and physical characteristics of the raceway, a three-dimensional transient Eulerian multiphase flow model in a packed particle bed was developed. In the model, it was assumed that the gas and solid (particle) phases constitute an interpenetrating continuum. The gas-phase turbulence was described as a k−ε dispersed model. The gas-phase stress was considered in terms of the effective viscosity of the gas. The solid-phase constitutive relationship was expressed in terms of solid stress. It was found that the evolution process of the raceway can be divided into three stages: (1) rapid expansion, (2) slow contraction, and (3) gradual stabilization. When the blast velocity was increased from 150 m/s to 300 m/s, the surface area of the raceway increased from 0.194 m2 t... [more]
Process Strategies for the Transition of 1G to Advanced Bioethanol Production
Ana Susmozas, Raquel Martín-Sampedro, David Ibarra, María E. Eugenio, Raquel Iglesias, Paloma Manzanares, Antonio D. Moreno
April 30, 2021 (v1)
Subject: Energy Policy
Keywords: bioeconomy, bioethanol, Biomass, integrated biorefineries, retrofitting
Nowadays, the transport sector is one of the main sources of greenhouse gas (GHG) emissions and air pollution in cities. The use of renewable energies is therefore imperative to improve the environmental sustainability of this sector. In this regard, biofuels play an important role as they can be blended directly with fossil fuels and used in traditional vehicles’ engines. Bioethanol is the most used biofuel worldwide and can replace gasoline or form different gasoline-ethanol blends. Additionally, it is an important building block to obtain different high added-value compounds (e.g., acetaldehyde, ethylene, 1,3-butadiene, ethyl acetate). Today, bioethanol is mainly produced from food crops (first-generation (1G) biofuels), and a transition to the production of the so-called advanced ethanol (obtained from lignocellulosic feedstocks, non-food crops, or industrial waste and residue streams) is needed to meet sustainability criteria and to have a better GHG balance. This work gives an ov... [more]
Some Physical Properties and Mass Modelling of Pepper Berries (Piper nigrum L.), Variety Kuching, at Different Maturity Levels
Puteri Nurain Megat Ahmad Azman, Rosnah Shamsudin, Hasfalina Che Man, Mohammad Effendy Ya’acob
April 30, 2021 (v1)
Keywords: dimensions, mass, maturity levels, Modelling, piper nigrum
Pepper berry (Piper nigrum L.) is known as the king of spices and has sharp, pungent flavour and aroma. In this study, the physical properties (weight, dimensions, sphericity, volume, surface area, and projected area) were measured, and the mass of pepper berries of the Kuching variety at different maturity levels (immature, mature, and ripe) was predicted using four models: linear, quadratic, s-curve, and power. When the models were based on volume and projected area, the mass could be predicted with maximum precision. The Quadratic model was best fitted for mass prediction at all mass maturity levels (immature, mature, and ripe). The results showed that mass modelling based on the actual volume of pepper berries was more applicable compared to other properties with the highest determination coefficient, 0.995, at the 1% probability level. From an economical point of view, mass prediction based on actual volume in the Quadratic form, M= 0.828 − 0.015 V + 7.376 ×10−5V2, is recommended.... [more]
NMPC-Based Workflow for Simultaneous Process and Model Development Applied to a Fed-Batch Process for Recombinant C. glutamicum
Philipp Levermann, Fabian Freiberger, Uma Katha, Henning Zaun, Johannes Möller, Volker C. Hass, Karl Michael Schoop, Jürgen Kuballa, Ralf Pörtner
April 30, 2021 (v1)
Keywords: C. glutamicum, digitalization, model-based process development, NMPC algorithm, process modeling, process optimization
For the fast and improved development of bioprocesses, new strategies are required where both strain and process development are performed in parallel. Here, a workflow based on a Nonlinear Model Predictive Control (NMPC) algorithm is described for the model-assisted development of biotechnological processes. By using the NMPC algorithm, the process is designed with respect to a target function (product yield, biomass concentration) with a drastically decreased number of experiments. A workflow for the usage of the NMPC algorithm as a process development tool is outlined. The NMPC algorithm is capable of improving various process states, such as product yield and biomass concentration. It uses on-line and at-line data and controls and optimizes the process by model-based process extrapolation. In this study, the algorithm is applied to a Corynebacterium glutamicum process. In conclusion, the potency of the NMPC algorithm as a powerful tool for process development is demonstrated. In pa... [more]
Hydrodynamics and Mass Transfer Analysis in BioFlow® Bioreactor Systems
Marian Kordas, Maciej Konopacki, Bartłomiej Grygorcewicz, Adrian Augustyniak, Daniel Musik, Krzysztof Wójcik, Magdalena Jędrzejczak-Silicka, Rafał Rakoczy
April 30, 2021 (v1)
Keywords: agitation, bioreactors, mass transfer, Mixing, Modelling, power consumption
Biotechnological processes involving the presence of microorganisms are realized by using various types of stirred tanks or laboratory-scale dual-impeller commercial bioreactor. Hydrodynamics and mass transfer rate are crucial parameters describing the functionality and efficiency of bioreactors. Both parameters strictly depend on mixing applied during bioprocesses conducted in bioreactors. Establishing optimum hydrodynamics conditions for the realized process with microorganisms maximizes the yield of desired products. Therefore, our main objective was to analyze and define the main operational hydrodynamic parameters (including flow field, power consumption, mixing time, and mixing energy) and mass transfer process (in this case, gas−liquid transfer) of two different commercial bioreactors (BioFlo® 115 and BioFlo® 415). The obtained results are allowed using mathematical relationships to describe the analyzed processes that can be used to predict the mixing process and mass transfer... [more]
Exploring the Function of Ion-Exchange Membrane in Membrane Capacitive Deionization via a Fully Coupled Two-Dimensional Process Model
Xin Zhang, Danny Reible
April 30, 2021 (v1)
Keywords: brackish water desalination, cycle time, hydraulic dispersion, ion transport and adsorption, ion-exchange membrane (IEM), membrane capacitive deionization (MCDI), non-ideal IEM, salt removal efficiency
In the arid west, the freshwater supply of many communities is limited, leading to increased interest in tapping brackish water resources. Although reverse osmosis is the most common technology to upgrade saline waters, there is also interest in developing and improving alternative technologies. Here we focus on membrane capacitive deionization (MCDI), which has attracted broad attention as a portable and energy-efficient desalination technology. In this study, a fully coupled two-dimensional MCDI process model capable of capturing transient ion transport and adsorption behaviors was developed to explore the function of the ion-exchange membrane (IEM) and detect MCDI influencing factors via sensitivity analysis. The IEM enhanced desalination by improving the counter-ions’ flux and increased adsorption in electrodes by encouraging retention of ions in electrode macropores. An optimized cycle time was proposed with maximal salt removal efficiency. The usage of the IEM, high applied volta... [more]
Construction and Automation of a Microcontrolled Solar Tracker
Juliano da Rocha Queiroz, Anacreone da Silva Souza, Maurício Klein Gussoli, Júlio César Dainezi de Oliveira, Cid Marcos Gonçalves Andrade
April 30, 2021 (v1)
Keywords: microcontroller, photovoltaic, Renewable and Sustainable Energy, solar tracker
A solar tracker can be defined as an electromechanical system capable of following the apparent path of the Sun, in order to orient an array of solar panels and/or collectors directly to the solar rays, maximizing the collected energy. Accordingly, the present work describes the process of building and automating a micro-controlled solar tracker. Two mobile structures were built, one equipped with high-precision step motors and four luminosity sensors separated in quadrants by a cross structure, and the other equipped with DC motors and the 275 Wp solar panel, allowing the design and evaluation of the behavior of each structure separately. The control and automation system is centralized in an Arduino MEGA2560 microcontroller, which runs the tracking and positioning algorithms. The built prototype allows us to carry out studies of solar tracking strategies based on sensor and control systems applied to DC motors.
Chaotic Mixing Analyzing in Continuous Mixer with Tracing the Morphology Development of a Polymeric Drop
Tao Chen, Hao Guo, Guo Li, Huajian Ji, Linsheng Xie, Yu Yang
April 30, 2021 (v1)
Subject: Other
Keywords: chaotic mixing, continuous mixer, morphology development, on-line visualization
The chaotic mixing process in a continuous mixer plays an important role and has an essential influence on the performance of prepared materials. To reveal how a polymeric drop experienced the chaotic mixing and give more specific analysis about the chaotic mixing, the morphology development of a single drop was traced and recorded with an on-line visualization system. The drop would undergo elongation deformation, reorientation, and folding process, which were the typical signs of chaotic mixing. The elongation deformation was an important precondition for drop experiencing the reorientation and folding process and mainly existed in the region near the barrier, rotor tip clearance, and wedgelike region. The reorientation and folding process mostly appeared in the region near the rotor flat and interaction window. Besides, the erosion process of the drop was observed at the initial stage under lower rotor rotation speed. The chaotic mixing always held the dominant place in continuous m... [more]
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