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Records Added in June 2020
Records added in June 2020
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157. LAPSE:2020.0604
Impact of Whole and Ground-by-Knife and Ball Mill Flax Seeds on the Physical and Sensorial Properties of Gluten Free-Bread
June 23, 2020 (v1)
Subject: Food & Agricultural Processes
Keywords: ball milling, flax, gluten-free bread, grinding, linseed
The aim of the study was to compare the physical and sensory properties of gluten-free bread with the addition of whole and ground flax seeds. The grinding process of flax seeds was carried out using a knife grinder and ball mill. After short-knife grinding (20 s) (GM-200, Retsch), the seeds were divided into whole (average particle size 0.634 mm), coarse (769 mm) and fine (0.328 mm) flour, and these flours were additionally ground with ball milling (60 s) (Pulverisette 6, Fritsh). The grinding energy of seeds was evaluated. Baking of gluten-free bread was performed with 10% addition of different forms of whole and ground flaxseeds. The colour, volume, texture and sensory parameters of bread were evaluated. In addition, the crumbling index of bread was developed and defined as the percentage share of crumbed pieces of the bread slice in relation to the mass of the entire crumb sample cut out together with crumbs. Specific grinding energy of flaxseeds during short (20 s) knife grinding... [more]
158. LAPSE:2020.0603
The Potential of Fractional Order Distributed MPC Applied to Steam/Water Loop in Large Scale Ships
June 22, 2020 (v1)
Subject: Process Control
Keywords: fractional order, large scale ships, Model Predictive Control, multi-input multi-output system, steam power plant
The steam/water loop is a crucial part of a steam power plant. However, satisfying control performance is difficult to obtain due to the frequent disturbance and load fluctuation. A fractional order model predictive control was studied in this paper to improve the control performance of the steam/water loop. Firstly, the dynamic of the steam/water loop was introduced in large-scale ships. Then, the model predictive control with an extended prediction self adaptive controller framework was designed for the steam/water loop with a distributed scheme. Instead of an integer cost function, a fractional order cost function was applied in the model predictive control optimization step. The superiority of the fractional order model predictive control was validated with reference tracking and load fluctuation experiments.
159. LAPSE:2020.0602
Concentration of Lipase from Aspergillus oryzae Expressing Fusarium heterosporum by Nanofiltration to Enhance Transesterification
June 22, 2020 (v1)
Subject: Biosystems
Keywords: fatty acid methyl ester, Fusarium heterosporum, lipase, nanofiltration
Nanofiltration membrane separation is an energy-saving technology that was used in this study to concentrate extracellular lipase and increase its total activity for biodiesel production. Lipase was produced by recombinant Aspergillus oryzae expressing Fusarium heterosporum lipase (FHL). A sulfonated polyethersulfone nanofiltration membrane, NTR-7410, with a molecular weight cut-off of 3 kDa was used for the separation, because recombinant lipase has a molecular weight of approximately 20 kDa, which differs from commercial lipase at around 30 kDa for CalleraTM Trans L (CalT). After concentration via nanofiltration, recombinant lipase achieved a 96.8% yield of fatty acid methyl ester (FAME) from unrefined palm oil, compared to 50.2% for CalT in 24 h. Meanwhile, the initial lipase activity (32.6 U/mL) of recombinant lipase was similar to that of CalT. The composition of FAME produced from recombinant concentrated lipase, i.e., C14:1, C16:0, C18:0, C18:1 cis, and C18:2 cis were 0.79%, 34.... [more]
160. LAPSE:2020.0601
Process Optimization of Microwave Assisted Simultaneous Distillation and Extraction from Siam cardamom using Response Surface Methodology
June 22, 2020 (v1)
Subject: Process Design
Keywords: 1,8-cineole, leaf sheath of Siam cardamom, microwave-assisted simultaneous distillation and extraction, response surface methodology
The main goal of the research was to optimize microwave-assisted simultaneous distillation and extraction (MA-SDE) using response surface methodology (RSM), based on Box−Behnken design (BBD). A process was designed to extract the essential oil from the leaf sheath of Siam cardamom. The experimental data were fitted to quadratic equations, and the experiment conditions for optimal extraction of 1,8-cineole were extraction time 87.68 min, material-to-water ratio 1:13.18 g/mL and microwave power 217.77 W. Under such conditions, the content of 1,8-cineole was 157.23 ± 4.23 µg/g, which matched with the predicted value. GC−MS results indicated the presence of predominant oxygenated monoterpenes including 1,8-cineole (20.63%), iso-carveol (14.30%), cis-p-mentha-1(7),8-dien-2-ol (12.27%) and trans-p-2,8-menthadien-1-ol (9.66%), and oxygenated contents were slightly higher in the MA-SDE and extraction compared to usual SDE. In addition, the essential oil extracted by MA-SDE exhibited strong ant... [more]
161. LAPSE:2020.0600
Petroleum Hydrocarbon Removal from Wastewaters: A Review
June 22, 2020 (v1)
Subject: Process Design
Keywords: Adsorption, advanced oxidation, coagulation, oil compounds, removal methods
Oil pollutants, due to their toxicity, mutagenicity, and carcinogenicity, are considered a serious threat to human health and the environment. Petroleum hydrocarbons compounds, for instance, benzene, toluene, ethylbenzene, xylene, are among the natural compounds of crude oil and petrol and are often found in surface and underground water as a result of industrial activities, especially the handling of petrochemicals, reservoir leakage or inappropriate waste disposal processes. Methods based on the conventional wastewater treatment processes are not able to effectively eliminate oil compounds, and the high concentrations of these pollutants, as well as active sludge, may affect the activities and normal efficiency of the refinery. The methods of removal should not involve the production of harmful secondary pollutants in addition to wastewater at the level allowed for discharge into the environment. The output of sewage filtration by coagulation and dissolved air flotation (DAF) floccul... [more]
162. LAPSE:2020.0599
Can Machine Learning Predict Stress Reduction Based on Wearable Sensors’ Data Following Relaxation at Workplace? A Pilot Study
June 22, 2020 (v1)
Subject: Intelligent Systems
Keywords: autonomic nervous system, ECG, galvanic skin response, heart rate, heart rate variability, Machine Learning, mindfulness, neural networks, relaxation, signal processing, skin conductance, wearable sensors, yoga
Nowadays, psychological stress represents a burdensome condition affecting an increasing number of subjects, in turn putting into practice several strategies to cope with this issue, including the administration of relaxation protocols, often performed in non-structured environments, like workplaces, and constrained within short times. Here, we performed a quick relaxation protocol based on a short audio and video, and analyzed physiological signals related to the autonomic nervous system (ANS) activity, including electrocardiogram (ECG) and galvanic skin response (GSR). Based on the features extracted, machine learning was applied to discriminate between subjects benefitting from the protocol and those with negative or no effects. Twenty-four healthy volunteers were enrolled for the protocol, equally and randomly divided into Group A, performing an audio-video + video-only relaxation, and Group B, performing an audio-video + audio-only protocol. From the ANS point of view, Group A sub... [more]
163. LAPSE:2020.0598
Saudi Rosmarinus officinalis and Ocimum basilicum L. Polyphenols and Biological Activities
June 22, 2020 (v1)
Subject: Biosystems
Keywords: antibacterial, antifungal, antioxidant, antiproliferative, cytotoxicity, flavonoids, leaf extract, Ocimum basilicum, phenolic acids, Rosmarinus officinalis
Investigating the polyphenolic profile of natural Rosmarinus officinalis and Ocimum basilicum populations may reveal essential compounds that have biological activities. Natural populations of R. officinalis and O. basilicum in Northern Riyadh were investigated by HPLC-DAD analyses. Several polyphenols, including rosmarinic acid, gentisic acid, 3,4-dihydroxyphenylacetic acid, rutoside, and others, out of 38 screened were confirmed. Rosmarinic acid was the major polyphenol in both of R. officinalis and O. basilicum. R. officinalis methanolic leaf extracts contained other phenols such as gentisic acid while O. basilicum contained also 3,4-dihydroxyphenylacetic acid and rutoside as well as others. R. officinalis showed higher antioxidant activities than O. basilicum using 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), and β-carotene bleaching assays. These higher activities are associated with a higher composition of rosmarinic acid in leaf extracts. The a... [more]
164. LAPSE:2020.0597
Influence of Carbon Quantum Dots on the Biome
June 22, 2020 (v1)
Subject: Biosystems
Keywords: agriculture, Carbon Quantum Dots, environmental implications, toxicity
The latest class of engineered nanomaterials, viz., carbon quantum dots (CQDs), has attracted attention because they are synthesized through green chemical procedures and from organic waste matter. The synthesis of these nano-sized particles synthesized from biomass such as fruit peel and other organic matter results in mixtures of CQD species that differ in chemical identity, activity and photo-physical properties. Generally used collectively as chemically heterogeneous ensemble, they have already had an impact on multiple sectors of our environment by use as wastewater sensors, switches, model agro-fertilizers, and in biomedicine. The transitioning of their applications to crops is an important crossover point that calls for an accurate and detailed assessment of their genomic, proteomic, and metabolomics impact on agriculturally important crops and produce. We review the current status of CQDs vis-à-vis their impact on the biosphere via recent model studies and comment on the knowle... [more]
165. LAPSE:2020.0596
Experimental Study on Hydrothermal Carbonization of Lignocellulosic Biomass with Magnesium Chloride for Solid Fuel Production
June 22, 2020 (v1)
Subject: Reaction Engineering
Keywords: additives, hydrothermal carbonization, lignocellulosic biomass, magnesium chloride, waste to energy
The effect of magnesium chloride as an additive of hydrothermal carbonization (HTC) of lignocellulosic biomass (Pinus radiata sawdust) was studied. The HTC tests were carried out at fixed conditions of temperature and residence time of 220 °C and 1 h, respectively, and varying the dose of magnesium chloride in the range 0.0−1.0 g MgCl2/g biomass. The carbonized product (hydrochar) was tested in order to determine its calorific value (HHV) while using PARR 6100 calorimeter, mass yield by gravimetry, elemental analysis using a LECO TruSpec elemental analyzer, volatile matter content, and ash content were obtained by standardized procedures using suitable ovens for it. The results show that using a dose of 0.75 g MgCl2/g biomass results in an impact on the mass yield that was almost equal to change operating conditions from 220 to 270 °C and from 0.5 to 1 h, without additive. Likewise, the calorific value increases by 33% for this additive dose, resulting in an energy yield of 68%, thus g... [more]
166. LAPSE:2020.0595
A Review of Methane Activation Reactions by Halogenation: Catalysis, Mechanism, Kinetics, Modeling, and Reactors
June 22, 2020 (v1)
Subject: Reaction Engineering
Keywords: Catalysis, density functional theory, halogenation, kinetics, mechanism, methane
Methane is the central component of natural gas, which is globally one of the most abundant feedstocks. Due to its strong C−H bond, methane activation is difficult, and its conversion into value-added chemicals and fuels has therefore been the pot of gold in the industry and academia for many years. Industrially, halogenation of methane is one of the most promising methane conversion routes, which is why this paper presents a comprehensive review of the literature on methane activation by halogenation. Homogeneous gas phase reactions and their pertinent reaction mechanisms and kinetics are presented as well as microkinetic models for methane reaction with chlorine, bromine, and iodine. The catalysts for non-oxidative and oxidative catalytic halogenation were reviewed for their activity and selectivity as well as their catalytic action. The highly reactive products of methane halogenation reactions are often converted to other chemicals in the same process, and these multi-step processe... [more]
167. LAPSE:2020.0594
Mathematical Model Based on the Shape of Pulse Waves Measured at a Single Spot for the Non-Invasive Prediction of Blood Pressure
June 22, 2020 (v1)
Subject: Biosystems
Keywords: blood pressure prediction, continuous non-invasive blood pressure, experimental model, pulse wave analysis
Background: Continuous non-invasive blood pressure (BP) measurement is a desired virtue in clinical practice. Unfortunately, current systems do not allow one for continuous, reliable BP measurement for more than a few hours per day, and they often require a complicated set of sensors to provide the necessary biosignals. Therefore we investigated the possibility of proposing a computational model that would predict the BP from pulse waves recorded in a single spot. Methods: Two experimental circuits were created. One containing a simple plastic tube for model development and a second with a silicone molded patient-specific arterial tree model. The first model served for the measuring of pulse waves under various BP (70−270 mmHg) and heart rate (60−190 beats per minute) values. Four different computational models were used to estimate the BP values from the diastolic time. The most accurate model was further validated using data from the latter experimental circuit containing a molded pa... [more]
168. LAPSE:2020.0593
A Critical Review of the Modeling and Optimization of Combined Heat and Power Dispatch
June 22, 2020 (v1)
Subject: Energy Management
Keywords: cogeneration, combined heat and power, economic dispatch, emission disptach, global optimization, metaheuristic optimization
Combined heat and power (CHP) systems are attracting increasing attention for their ability to improve the economics and sustainability of the electricity system. Determining how to best operate these systems is difficult because they can consist of many generating units whose operation is governed by complex nonlinear physics. Mathematical programming is a useful tool to support the operation of CHP systems, and has been the subject of substantial research attention since the early 1990s. This paper critically reviews the modeling and optimization work that has been done on the CHP economic dispatch problem, and the CHP economic and emission dispatch problem. A summary of the common models used for these problems is provided, along with comments on future modeling work that would beneficial to the field. The majority of optimization approaches studied for CHP system operation are metaheuristic algorithms. A discussion of the limitations and benefits of metaheuristic algorithms is give... [more]
169. LAPSE:2020.0592
Study of Blockage Diagnosis for Hydrocyclone Using Vibration-Based Technique Based on Wavelet Denoising and Discrete-Time Fourier Transform Method
June 22, 2020 (v1)
Subject: Process Monitoring
Keywords: blockage diagnosis, discrete-time Fourier transform, hydrocyclone, vibration-based technique, wavelet denoising
Hydrocyclones are extensively known as important separation devices which are used in many industrial fields. However, the general method to estimate device performance is time-consuming and has a high cost. The aim of this paper was to investigate the blockage diagnosis for a lab-scale hydrocyclone using a vibration-based technique based on wavelet denoising and the discrete-time Fourier transform method. The results indicate that the farther away the installation location from feed inlet the more regular the frequency is, which reveals that the installation plane near to the spigot generated the regular frequency distribution. Furthermore, the acceleration amplitude under blockage degrees 0%, 50% and 100% fluctuates as a sine shape with increasing time, meanwhile the vibration frequency of the hydrocyclone rises with increasing throughput. Moreover, the distribution of four dimensional and five non-dimensional parameters for the time domain shows that the standard deviation, compared... [more]
170. LAPSE:2020.0591
Numerical Investigation of Fluid Flow and In-Cylinder Air Flow Characteristics for Higher Viscosity Fuel Applications
June 22, 2020 (v1)
Subject: Modelling and Simulations
Keywords: alternative fuel, biofuel, emulsified biofuel, piston bowl, vanes
Generally, the compression ignition (CI) engine that runs with emulsified biofuel (EB) or higher viscosity fuel experiences inferior performance and a higher emission compared to petro diesel engines. The modification is necessary to standard engine level in order to realize its application. This paper proposes a guide vane design (GVD), which needs to be installed in the intake manifold, is incorporated with shallow depth re-entrance combustion chamber (SCC) pistons. This will organize and develop proper in-cylinder airflow to promote better diffusion, evaporation and combustion processes. The model of GVD and SCC piston was designed using SolidWorks 2017; while ANSYS Fluent version 15 was utilized to run a 3D analysis of the cold flow IC engine. In this research, seven designs of GVD with the number of vanes varied from two to eight vanes (V2−V8) are used. The four-vane model (V4) has shown an excellent turbulent flow as well as swirl, tumble and cross tumble ratios in the fuel-injec... [more]
171. LAPSE:2020.0590
Conflicting Effects of Coffee Consumption on Cardiovascular Diseases: Does Coffee Consumption Aggravate Pre-existing Risk Factors?
June 22, 2020 (v1)
Subject: Biosystems
Keywords: cardiovascular disease, coffee consumption, confounders, dose-response, risk factors
Coffee is one of the most popular beverages worldwide. Its effect on health is generally regarded as beneficial in many studies. However, there are growing concerns about the adverse effect of coffee consumption on cardiovascular disease (CVD) due to the potential aggravating impact on the cardiovascular system attributed to various compounds within coffee. This review is focused on deteriorative effects of coffee consumption on CVDs with possible mechanisms. Patients with risk factors of CVDs should prudently consider heavy consumption of coffee as it may exacerbate hypertension, dyslipidemia, and atherosclerosis, and increase the odds of cardiovascular events. J-shaped or U-shaped dose-response graphs of coffee consumption and CVD parameters partially explain the inconsistency of conclusions between coffee studies on CVD, highlighting a moderate intake of coffee. Moreover, there are discrepancies in results from clinical studies elucidating considerable influences of confounding fact... [more]
172. LAPSE:2020.0589
Infrared Infusion Monitor Based on Data Dimensionality Reduction and Logistics Classifier
June 22, 2020 (v1)
Subject: Intelligent Systems
Keywords: data dimensionality reduction, drop count, logistics classifier
This paper presents an infrared infusion monitoring method based on data dimensionality reduction and a logistics classifier. In today’s social environment, nurses with hospital infusion work are under excessive pressure. In order to improve the information level of the traditional medical process, hospitals have introduced a variety of infusion monitoring devices. The current infusion monitoring equipment mainly adopts the detection method of infrared liquid drop detection to realize non-contact measurements. However, a large number of experiments have found that the traditional infrared detection method has the problems of low voltage signal amplitude variation and low signal-to-noise ratio (SNR). Conventional threshold judgment or signal shaping cannot accurately judge whether droplets exist or not, and complex signal processing circuits can greatly increase the cost and power consumption of equipment. In order to solve these problems, this paper proposes a method for the accurate m... [more]
173. LAPSE:2020.0588
Biotechnology and Bioprocesses: Their Contribution to Sustainability
June 22, 2020 (v1)
Subject: Biosystems
Keywords: applications, bioeconomy, bioprocesses, policy, social welfare, Sustainability
Significant advancements in biotechnology have resulted in the development of numerous fundamental bioprocesses, which have consolidated research and development and industrial progress in the field. These bioprocesses are used in medical therapies, diagnostic and immunization procedures, agriculture, food production, biofuel production, and environmental solutions (to address water-, soil-, and air-related problems), among other areas. The present study is a first approach toward the identification of scientific and technological bioprocess trajectories within the framework of sustainability. The method included a literature search (Scopus), a patent search (Patentscope), and a network analysis for the period from 2010 to 2019. Our results highlight the main technological sectors, countries, institutions, and academic publications that carry out work or publish literature related to sustainability and bioprocesses. The network analysis allowed for the identification of thematic cluste... [more]
174. LAPSE:2020.0587
Biorefining Oat Husks into High-Quality Lignin and Enzymatically Digestible Cellulose with Acid-Catalyzed Ethanol Organosolv Pretreatment
June 10, 2020 (v1)
Subject: Reaction Engineering
Keywords: delignification, digestible glucan, high-quality lignin, oat husks, organosolv pretreatment
Oat husks are low-value lignocellulosic residues of oat processing that carry an environmental impact. Their polymers (cellulose, hemicellulose, and lignin) can be converted into a wide variety of value-added products; however, efficient pretreatment methods are needed that allow their fine separation for further tailored valorization. This study pioneered the use of milling-free and low acid-catalyzed ethanol organosolv for the delignification of oat husks, allowing their conversion into three high-quality streams, namely, glucan-rich, lignin-rich, and hemicellulosic compound-rich streams. Temperature, retention time, and solid-to-liquid ratio were found to impact the delignification of oat husks when using a one-factor-at-a-time strategy. The ideal conditions that were found (210 °C, 90 min, and solid-to-liquid ratio of 1:2) culminated into glucan and lignin fractions containing 74.5% ± 11.4% glucan and 74.9% ± 7.6% lignin, respectively. These high-purity lignin fractions open the po... [more]
175. LAPSE:2020.0586
Conventional and Emerging Extraction Processes of Flavonoids
June 10, 2020 (v1)
Subject: Biosystems
Keywords: biotransformation, extraction methods, flavonoids, human health
Flavonoids are a group of plant constituents called phenolic compounds and correspond to the nonenergy part of the human diet. Flavonoids are found in vegetables, seeds, fruits, and beverages such as wine and beer. Over 7000 flavonoids have been identified and they have been considered substances with a beneficial action on human health, particularly of multiple positive effects because of their antioxidant and free radical scavenging action. Although several studies indicate that some flavonoids have provident actions, they occur only at high doses, confirming in most investigations the existence of anti-inflammatory effects, antiviral or anti-allergic, and their protective role against cardiovascular disease, cancer, and various pathologies. Flavonoids are generally removed by chemical methods using solvents and traditional processes, which besides being expensive, involve long periods of time and affect the bioactivity of such compounds. Recently, efforts to develop biotechnological... [more]
176. LAPSE:2020.0585
An Autonomous Power-Frequency Control Strategy Based on Load Virtual Synchronous Generator
June 10, 2020 (v1)
Subject: Process Control
Keywords: autonomous power-frequency control strategy, dynamic small-signal model, hybrid AC/DC microgrid, virtual synchronous generator
With the increasing penetration of the hybrid AC/DC microgrid in power systems, an inertia decrease of the microgrid is caused. Many scholars have put forward the concept of a virtual synchronous generator, which enables the converters of the microgrid to possess the characteristics of a synchronous generator, thus providing inertia support for the microgrid. Nevertheless, the problems of active power oscillation and unbalance would be serious when multiple virtual synchronous generators (VSGs) operate in the microgrid. To conquer these problems, a VSG-based autonomous power-frequency control strategy is proposed, which not only independently allocates the power grid capacity according to the load capacity, but also effectively suppresses the active power oscillation. In addition, by establishing a dynamic small-signal model of the microgrid, the dynamic stability of the proposed control strategy in the microgrid is verified, and further reveals the leading role of the VSG and filter i... [more]
177. LAPSE:2020.0584
Thermal Pyrolysis of Polystyrene Aided by a Nitroxide End-Functionality. Experiments and Modeling
June 10, 2020 (v1)
Subject: Reaction Engineering
Keywords: mathematical modeling, nitroxide mediated polymerization, polystyrene, thermal pyrolysis
The thermal pyrolysis of polystyrene (PS) is gaining importance as the social pressure for achieving a circular economy is growing; moreover, the recovery of styrene monomer in such a process is especially relevant. In this study, a simple thermal pyrolysis process in the temperature range of 390−450 °C is developed. A working hypothesis is that by using a nitroxide-end functionalized PS (PS-T or dormant polymer), the initiation process for the production of monomer (unzipping) during the PS pyrolysis could be enhanced due to the tendency of the PS-T to activate at the nitroxide end. Two types of PS were used in this work, the first one was synthesized by free-radical polymerization (FRP-dead polymer) and the second by nitroxide-mediated polymerization (NMP) using three levels of nitroxide to initiator ratio: 1.3, 1.1, and 0.9. Analysis of the recovered products of the pyrolysis by gas-mass spectroscopy shows that the yield of styrene increases from ∼33% in the case of dead polymer to... [more]
178. LAPSE:2020.0583
Investigating Data-Driven Systems as Digital Twins: Numerical Behavior of Ho−Kalman Method for Order Estimation
June 10, 2020 (v1)
Subject: System Identification
Keywords: digital twin, manufacturing process, system identification, system order
System identification has been a major advancement in the evolution of engineering. As it is by default the first step towards a significant set of adaptive control techniques, it is imperative for engineers to apply it in order to practice control. Given that system identification could be useful in creating a digital twin, this work focuses on the initial stage of the procedure by discussing simplistic system order identification. Through specific numerical examples, this study constitutes an investigation on the most “natural” method for estimating the order from responses in a convenient and seamless way in time-domain. The method itself, originally proposed by Ho and Kalman and utilizing linear algebra, is an intuitive tool retrieving information out of the data themselves. Finally, with the help of the limitations of the methods, the potential future outlook is discussed, under the prism of forming a digital twin.
179. LAPSE:2020.0582
Facile Synthesis of Silver Nanoparticles Using Asian Spider Flower and Its In Vitro Cytotoxic Activity Against Human Breast Carcinoma Cells
June 10, 2020 (v1)
Subject: Biosystems
Keywords: anticancer activity, apoptotic protein-caspases, breast cancer cell lines, cytotoxicity, green biosynthesis, silver nanoparticles
Cancer is one of the most dangerous threats to human health and possibly the utmost task for current medicine. Currently, bio-based synthesis of nanoparticles from plants has gained much interest due to its potential medicinal applications. In the present study, a biological approach was employed for biogenic (green) synthesis of silver nanoparticles (AgNPs) using dried leaf extract of Asian spider flower (Asf). The biogenic synthesis of Asf-AgNPs (Asian spider flower-Silver nanoparticles) was established using ultra violet-visible (UV-vis) spectra which exhibited a wide superficial plasmon resonance of AgNPs at 445 nm. These nanoparticles clearly showed the formation of poly-disperse crystalline solids (spherical shape) with particle size range of <50 nm based on observation under a transmission electron microscope (TEM). Infrared spectroscopy (FTIR) revealed carboxylic acids (C = O stretch) known to act as a capping agent and a reductant in plant extracts. Elemental silver signal... [more]
180. LAPSE:2020.0581
Aerodynamic Studies on Non-Premixed Oxy-Methane Flames and Separated Oxy-Methane Cold Jets
June 10, 2020 (v1)
Subject: Modelling and Simulations
Keywords: aerodynamic mixing, combustion, jet instability, radial velocity, turbulent kinetic energy
Both cold and flame jets find numerous applications in different fields, ranging from domestic applications to aerospace and space technology. Indeed, the applications of isothermal and non-isothermal jets in the flame heating industry fascinated the researchers to gain an in-depth understanding. Nevertheless, these benefits are not standalone, rather, they are associated with major disadvantages such as improper jet mixing and flame instabilities that require careful remedies. In the present investigation, three-inline jets, having methane jet at the center and two oxygen jets at the periphery, are studied computationally in a three-dimensional domain, with and without considering the effects of combustion. To study the mixing characteristics of cold jets, the radial velocity distributions at different streamwise locations have been analyzed at the jet inlet velocity of 27 m/s. However, for oxygen and methane flame jets, inlet velocities are varied as 27 m/s and 54 m/s. Moreover, to i... [more]
181. LAPSE:2020.0580
Variable Wall Permeability Effects on Flow and Heat Transfer in a Leaky Channel Containing Water-Based Nanoparticles
June 10, 2020 (v1)
Subject: Modelling and Simulations
Keywords: analytic solution, Brinkman number, heat transfer rate, Leaky channel, regular perturbation method
This work presents the effects of variable wall permeability on two-dimensional flow and heat transfer in a leaky narrow channel containing water-based nanoparticles. The nanofluid is absorbed through the walls with an exponential rate. This situation arises in reverse osmosis, ultrafiltration, and transpiration cooling in industry. The mathematical model is developed by using the continuity, momentum, and energy equations. Using stream function, the transport equations are reduced and solved by using regular perturbation method. The expressions for stream function and temperature distribution are established, which helps in finding the components of velocity, wall shear stress, and heat transfer rate inside the channel. The results show that velocity components, temperature, wall shear stress, and rate of heat transfer are minimum at the entrance region due to the reabsorption of fluid containing nanoparticles. Additionally, with increasing volume fraction of nanoparticles, the rate o... [more]
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