Records Added in August 2019
Records added in August 2019
Change year: 2018 | 2019 | 2020
Change month: January | February | March | April | May | June | July | August | September | October | November | December
Showing records 1 to 25 of 77. [First] Page: 1 2 3 4 Last
Illustrating Molecular-Level Phenomena and Molecular Simulation Techniques with Commonly Used Software
Rachel Getman
August 24, 2019 (v1)
Subject: Education
Keywords: Chemical Reaction Engineering, Intermolecular Forces, Matlab, Microsoft Excel, Molecular simulations, Molecular-level phenomena, Monte Carlo, Python, Quantum Simulations, WebMO
While topics in the chemical engineering curriculum generally involve the macroscale, e.g., focusing on process design and optimizations, many of the grand challenges facing chemical engineers today involve molecular level chemistry. Having an appreciation for molecular-level phenomena will better prepare chemical engineers to handle problems in energy, water, food, catalysis, advanced materials, and other fields. In this presentation, we discuss homework/project problems that we have developed for use in the Material and Energy Balances, Separations, Kinetics, and Thermodynamics courses that explore molecular level phenomena and molecular-level simulation approaches. Specifically, these problems focus on intermolecular interactions, connections between molecular configurations and macroscopic observables, how molecular level properties control material performance, and simulation strategies that enable exploration of the molecular level. An aim of the assignments is to demonstrate sim... [more]
Effect of the Marangoni Convection in the Unsteady Thin Film Spray of CNT Nanofluids
Ali Rehman, Taza Gul, Zabidin Salleh, Safyan Mukhtar, Fawad Hussain, Kottakkaran Sooppy Nisar, Poom Kumam
August 15, 2019 (v1)
Subject: Materials
Keywords: extending cylinder, Marangoni convection, OHAM and ND-solve methods, SWCNT/MWCNT nanofluid
The gradient of surface temperature is known as Marangoni convection and plays an important role in silicon melt, spray, atomic reactors, and thin fluid films. Marangoni convection has been considered in the liquid film spray of carbon nanotube (CNT) nanofluid over the unsteady extending surface of a cylinder. The two kinds of CNTs, single-wall carbon nanotubes (SWCNTs) and multiple-wall carbon nanotubes (MWCNTs), formulated as water-based nanofluids have been used for thermal spray analysis. The thickness of the nanofluid film was kept variable for a stable spray rate and pressure distribution. The transformed equations of the flow problem have been solved using the optimal homotopy analysis method (OHAM). The obtained results have been validated through the sum of the total residual errors numerically and graphically for both types of nanofluids. The impact of the physical parameters versus velocity, pressure, and temperature pitches under the influence of the Marangoni convection ha... [more]
Exergy Analysis and Evaluation of the Different Flowsheeting Configurations for CO2 Capture Plant Using 2-Amino-2-Methyl-1-Propanol (AMP)
Ebuwa Osagie, Aliyu M. Aliyu, Somtochukwu Godfrey Nnabuife, Osaze Omoregbe, Victor Etim
August 15, 2019 (v1)
Keywords: 2-Amino-2-Methyl-1-Propanol, exergy analysis, flowsheeting configurations, modelling and Simulation, post-combustion capture
This paper presents steady-state simulation and exergy analysis of the 2-amino-2-methyl-1-propanol (AMP)-based post-combustion capture (PCC) plant. Exergy analysis provides the identification of the location, sources of thermodynamic inefficiencies, and magnitude in a thermal system. Furthermore, thermodynamic analysis of different configurations of the process helps to identify opportunities for reducing the steam requirements for each of the configurations. Exergy analysis performed for the AMP-based plant and the different configurations revealed that the rich split with intercooling configuration gave the highest exergy efficiency of 73.6%, while that of the intercooling and the reference AMP-based plant were 57.3% and 55.8% respectively. Thus, exergy analysis of flowsheeting configurations can lead to significant improvements in plant performance and lead to cost reduction for amine-based CO2 capture technologies.
Direct Observation of Growth Rate Dispersion in the Enzymatic Reactive Crystallization of Ampicillin
Matthew A. McDonald, Andreas S. Bommarius, Martha A. Grover, Ronald W. Rousseau
August 15, 2019 (v1)
Subject: Biosystems
Keywords: growth rate dispersion, penicillin G acylase, β-lactam antibiotics
Prediction and control of crystal size distributions, a prerequisite for production of consistent crystalline material in the pharmaceutical industry, requires knowledge of potential non-idealities of crystal growth. Ampicillin is one such medicine consumed in crystal form (ampicillin trihydrate). Typically it is assumed that all crystals of the same chemical and geometric type grow at the same rate, however a distribution of growth rates is often observed experimentally. In this study, ampicillin produced enzymatically is crystallized and a distribution of growth rates is observed as individual crystals are monitored by microscopy. Most studies of growth rate dispersion use complex flow apparatuses to maintain a constant supersaturation or imprecise measurements of size distributions to reconstruct growth rate dispersions. In this study, the controllable enzyme reaction enables the same information to be gathered from fewer, less complicated experiments. The growth rates of individual... [more]
Design and Performance of Nonlinear Control for an Electro-Hydraulic Actuator Considering a Wearable Robot
Buchun Song, Dongyoung Lee, Sang Yong Park, Yoon Su Baek
August 15, 2019 (v1)
Keywords: adaptive sliding mode control, locking circuit design, pump-controlled electro-hydraulic actuator
In the development of a wearable robot, compact volume size, high energy efficiency, and a high load capacity linear actuator system are necessary. However, conventional hydraulic actuator systems are difficult to apply to wearable robots. Also, they have nonlinearities because of the presence of hydraulic fluid in a single rod cylinder. Electric linear actuators resolve the problems of hydraulic systems. However, due to their low load capacity, they are not easy to apply to wearable robots. In this paper, a pump-controlled electro-hydraulic actuator (EHA) system that considers the disadvantages of the hydraulic actuator and electric actuator is proposed for a wearable robot. Initially, a locking circuit design is considered for the EHA to give the system load holding capacity. Based on the developed model, the adaptive sliding mode control (ASMC) scheme is designed to resolve the nonlinearity problem of changes in the dynamic system. The ASMC scheme is then modeled and verified with S... [more]
Increasing Iron and Reducing Phosphorus Grades of Magnetic-Roasted High-Phosphorus Oolitic Iron Ore by Low-Intensity Magnetic Separation−Reverse Flotation
Junhui Xiao, Lingli Zhou
August 15, 2019 (v1)
Subject: Materials
Keywords: iron increase, low-intensity magnetic separation, phosphorous reduction, phosphorus mineral flotation reagent, reverse flotation, suspended magnetic roast
High-phosphorus oolitic iron ore, treated by suspended flash magnetic roasting, contained 42.73% iron (mainly present as magnetite) and 0.93% phosphorus (present as collophane). Low-intensity magnetic separation (LIMS) was combined with reverse flotation to increase the iron and reduce the phosphorus contents of the roasted product. The results showed that an optimized iron ore concentrate with an iron grade of 67.54%, phosphorus content of 0.11%, and iron recovery of 78.99% were obtained under LIMS conditions that employed a grind of 95% −0.038 mm and a magnetic field of 0.10 T. Optimized rougher reverse-flotation conditions used a pulp pH of 9 and dosages of toluenesulfonamide, starch, and pine alcohol oil of 800 g/t, 1000 g/t, and 40 g/t, respectively; optimized scavenging conditions used a pulp pH of 9 and dosages of toluenesulfonamide, starch, and pine alcohol oil of 400 g/t, 500 g/t, and 20 g/t, respectively. Study of the mechanism of phosphorus reduction showed that the toluenes... [more]
Computational Study of MHD Nanofluid Flow Possessing Micro-Rotational Inertia over a Curved Surface with Variable Thermophysical Properties
Zahid Ahmed, Ali Al-Qahtani, Sohail Nadeem, Salman Saleem
August 15, 2019 (v1)
Subject: Other
Keywords: carbon nanotubes, curved surface, MHD, nanofluids, variable viscosity
This work presents a numerical investigation of viscous nanofluid flow over a curved stretching surface. Single-walled carbon nanotubes were taken as a solid constituent of the nanofluids. Dynamic viscosity was assumed to be an inverse function of fluid temperature. The problem is modeled with the help of a generalized theory of Eringen Micropolar fluid in a curvilinear coordinates system. The governing systems of non-linear partial differential equations consist of mass flux equation, linear momentum equations, angular momentum equation, and energy equation. The transformed ordinary differential equations for linear and angular momentum along with energy were solved numerically with the help of the Keller box method. Numerical and graphical results were obtained to analyze the flow characteristic. It is perceived that by keeping the dynamic viscosity temperature dependent, the velocity of the fluid away from the surface rose in magnitude with the values of the magnetic parameter, whil... [more]
Determination of Holmquist−Johnson−Cook Constitutive Parameters of Coal: Laboratory Study and Numerical Simulation
Beijing Xie, Zheng Yan, Yujing Du, Zeming Zhao, Xiaoqian Zhang
August 15, 2019 (v1)
Keywords: Holmquist–Johnson–Cook constitutive model of briquette, numerical simulation, parameter acquisition, split Hopkinson pressure bar experiment
The main sensitivity parameters of the Holmquist−Johnson−Cook constitutive model for coal were obtained from a variety of tests such as uniaxial compression, uniaxial cyclic loading, splitting and triaxial compression tests, as well as the indirect derivation equation of a briquette. The mechanical properties of briquettes under dynamic impact were investigated using a split Hopkinson pressure bar experiment. Based on the experimental measurement of the Holmquist−Johnson−Cook constitutive model, the numerical simulation of briquette was performed using ANSYS/LS-DYNA software. A comparison between experimental and simulation results verified the correctness of simulation parameters. This research concluded that the failure of briquette at different impact velocities started from an axial crack in the middle of the coal body, and the sample was swollen to some extent. By the increase of impact velocity, the severity of damage in the coal body was increased, while the size of the coal blo... [more]
Supercritical Fluid Extraction of Fat and Caffeine with Theobromine Retention in the Cocoa Shell
Fanny Adabel González-Alejo, Juan Barajas-Fernández, María de los Ángeles Olán-Acosta, Laura Mercedes Lagunes-Gálvez, Pedro García-Alamilla
August 15, 2019 (v1)
Subject: Biosystems
Keywords: caffeine, cocoa shell, extraction of fat, supercritical extraction, theobromine
The cocoa shell is a residue of low commercial value, which represents an alternative for obtaining substances of added value for the food and pharmaceutical industry. Substances of interest in the shell include fat and methylxanthines (theobromine and caffeine). In order to obtain the extraction behavior with supercritical CO2, a 23 factorial design was proposed with six central points, taking dynamic extraction into consideration. The following factors were involved: pressure (2,000−6,000 psi), temperature (313−333 K), and time (30−90 min). The obtained yield was between 3.66% and 15.30%. Fat was the substance that was extracted most effectively (94.73%). Caffeine demonstrated variability in the residue, with at least six treatments that exceeded a removal rate of more than 90%, while it was practically impossible to extract theobromine. The difference with regard to the extraction of theobromine may be attributed to its low solubility. Characterization using FT−IR showed the modific... [more]
Separating Electronic from Steric Effects in Ethene/α-Olefin Copolymerization: A Case Study on Octahedral [ONNO] Zr-Catalysts
Francesco Zaccaria, Roberta Cipullo, Andrea Correa, Peter H. M. Budzelaar, Vincenzo Busico, Christian Ehm
August 15, 2019 (v1)
Keywords: DFT, electronic effects, insertion kinetics, olefin capture, olefin copolymerization, post-metallocene, reactivity ratios, salan catalysts
Four Cl/Me substituted [ONNO] Zr-catalysts have been tested in ethene/α-olefin polymerization. Replacing electron-donating methyl with isosteric but electron-withdrawing chlorine substituents results in a significant increase of comonomer incorporation. Exploration of steric and electronic properties of the ancillary ligand by DFT confirm that relative reactivity ratios are mainly determined by the electrophilicity of the metal center. Furthermore, quantitative DFT modeling of propagation barriers that determine polymerization kinetics reveals that electronic effects observed in these catalysts affect relative barriers for insertion and a capture-like transition state (TS).
Concept of Designing Thermal Condition Monitoring System with ZigBee/GSM Communication Link for Distributed Energy Resources Network in Rural and Remote Applications
Emmanuel Kobina Payne, Shulin Lu, Qian Wang, Licheng Wu
August 15, 2019 (v1)
Keywords: distributed energy resources, thermal condition monitoring, wireless sensor networks, ZigBee/GSM communications
Monitoring the thermal behavior of distributed energy resources (DERs) network explores the dualism between thermal effects and electrical power flow. This paper proposes a design concept that monitors thermal conditions of DER grids, using ZigBee/GSM wireless sensor networks (WSNs) for real-time monitoring in rural and remote areas. The concept seeks to improve upon existing designs by integrating composite functions. The functions comprise temperature conditions monitoring, data acquisition, and wireless data transmission including data storage and abnormal conditions alert/notification for control solutions. Thus, the concept determines the thermal impact on the DERs integrated network. WSNs with temperature sensors LM35 are utilized to complement ZigBee and Global System for Mobile Communications (GSM) technologies as a communication assisted link. Temperatures are measured from solar Photovoltaic PV modules, wind turbine, distribution cables, protection control units, and energy s... [more]
Separation Emulsion via Non-Ionic Surfactant: An Optimization
Murtada Mohammed Abdulredha, Siti Aslina Hussain, Luqman Chuah Abdullah
August 15, 2019 (v1)
Subject: Other
Keywords: demulsification, non-ionic surfactant, RSM, water-in-oil emulsion
Achieving emulsion stability in the petroleum industry is a major challenge due to several problems encountered in the oil refining process, such as corrosion in equipment, high-pressure drops in pipelines, and catalyst poisoning in upstream facilities. Thus, several methods are applied for emulsion treatment and chemical treatment using surface-active agents, a fundamental method in the petroleum industry. The present work investigated the performance of a non-ionic surfactant in separating water in a crude oil emulsion via the bottle test technique. Then, a Fractional Factorial Design (2K−1) was used to characterise the effect of significant variables. In particular, a Pareto chart was employed and factors such as demulsifier dosage, toluene concentration, pressure, sitting time, and temperature were investigated. Accordingly, the parameters applied were further analysed using a Central Composite Design (CCD) based on the Response Surface Method (RSM). The experimental results based... [more]
Influence of Particle Charge and Size Distribution on Triboelectric Separation—New Evidence Revealed by In Situ Particle Size Measurements
Johann Landauer, Petra Foerst
August 15, 2019 (v1)
Subject: Materials
Keywords: binary mixture, charge estimation, in situ particle size measurement, particle charge, particle size distribution, triboelectric separation
Triboelectric charging is a potentially suitable tool for separating fine dry powders, but the charging process is not yet completely understood. Although physical descriptions of triboelectric charging have been proposed, these proposals generally assume the standard conditions of particles and surfaces without considering dispersity. To better understand the influence of particle charge on particle size distribution, we determined the in situ particle size in a protein−starch mixture injected into a separation chamber. The particle size distribution of the mixture was determined near the electrodes at different distances from the separation chamber inlet. The particle size decreased along both electrodes, indicating a higher protein than starch content near the electrodes. Moreover, the height distribution of the powder deposition and protein content along the electrodes were determined in further experiments, and the minimum charge of a particle that ensures its separation in a give... [more]
Dynamic Modelling of Phosphorolytic Cleavage Catalyzed by Pyrimidine-Nucleoside Phosphorylase
Robert T. Giessmann, Niels Krausch, Felix Kaspar, Mariano Nicolas Cruz Bournazou, Anke Wagner, Peter Neubauer, Matthias Gimpel
August 15, 2019 (v1)
Keywords: Dynamic Modelling, enzymatic reaction, ODE model, process kinetics, pyrimidine-nucleoside phosphorylase, reversible reaction, spectroscopic assay
Pyrimidine-nucleoside phosphorylases (Py-NPases) have a significant potential to contribute to the economic and ecological production of modified nucleosides. These can be produced via pentose-1-phosphates, an interesting but mostly labile and expensive precursor. Thus far, no dynamic model exists for the production process of pentose-1-phosphates, which involves the equilibrium state of the Py-NPase catalyzed reversible reaction. Previously developed enzymological models are based on the understanding of the structural principles of the enzyme and focus on the description of initial rates only. The model generation is further complicated, as Py-NPases accept two substrates which they convert to two products. To create a well-balanced model from accurate experimental data, we utilized an improved high-throughput spectroscopic assay to monitor reactions over the whole time course until equilibrium was reached. We examined the conversion of deoxythymidine and phosphate to deoxyribose-1-p... [more]
Analysis of the Trends in Biochemical Research Using Latent Dirichlet Allocation (LDA)
Hee Jay Kang, Changhee Kim, Kyungtae Kang
August 15, 2019 (v1)
Subject: Biosystems
Keywords: biochemistry, LDA, research trend, topic modeling
Biochemistry has been broadly defined as “chemistry of molecules included or related to living systems”, but is becoming increasingly hard to be distinguished from other related fields. Targets of its studies evolve rapidly; some newly emerge, disappear, combine, or resurface themselves with a fresh viewpoint. Methodologies for biochemistry have been extremely diversified, thanks particularly to those adopted from molecular biology, synthetic chemistry, and biophysics. Therefore, this paper adopts topic modeling, a text mining technique, to identify the research topics in the field of biochemistry over the past twenty years and quantitatively analyze the changes in its trends. The results of the topic modeling analysis obtained through this study will provide a helpful tool for researchers, journal editors, publishers, and funding agencies to understand the connections among the diverse sub-fields in biochemical research and even see how the research topics branch out and integrate wit... [more]
Performance Evaluation of Sustainable Soil Stabilization Process Using Waste Materials
Muhammad Aamir, Zarnish Mahmood, Aqsa Nisar, Amjad Farid, Tanveer Ahmed Khan, Mudassir Abbas, Muhammad Ismaeel, Syyed Adnan Raheel Shah, Muhammad Waseem
August 15, 2019 (v1)
Keywords: processes, stabilization, strength improvement, sustainable, waste management
The process of soil stabilization is a fundamental requirement before road infrastructure development is possible. Different binding materials have been used worldwide as soil stabilizers. In this study, water treatment waste (i.e., alum sludge (AS)) was used as a soil stabilizer. Alum sludge can work not only as a low-cost soil stabilizer but also can solve the problem of waste management at a large scale. Utilization of alum waste can be a sustainable solution and environmentally friendly exercise. Thus, in consideration of the pozzolanic properties of alum, it was applied as a binder, similar to cement or lime, to stabilize the soil with the addition of 2%, 4%, 6%, 8%, and 10% of dry soil by weight. To analyze the resulting improvement in soil strength, the California Bearing Ratio (CBR) test was conducted in addition to three other tests (i.e., particle size analysis, Atterberg’s limits test, and modified proctor test). The soil bearing ratio was significantly improved from 6.53% t... [more]
Design and Optimization of a Process for the Production of Methyl Methacrylate via Direct Methylation
Taotao Liang, Xiaogang Guo, Abdulmoseen Segun Giwa, Jianwei Shi, Yujin Li, Yan Wei, Xiaojuan Wang, Xuansong Cao, Xiaofeng Tang, Jialun Du
August 15, 2019 (v1)
Keywords: double-effect distillation, energy conservation, MAL, MMA, purity
Methyl methacrylate (MMA) plays a vital role in national productions with broad application. Herein, the production of MMA is realized by the improved eco-friendly direct methylation method using Aspen Plus software. Three novel kinds of energy-saving measures were proposed in this study, including the recycle streams of an aqueous solution, methacrolein (MAL), and methanol, the deployment of double-effect distillation instead of a normal one, and the design of a promising heat-exchange network. Moreover, MMA with a purity of 99.9% is obtained via the design of a MAL absorber column with an optimal stage number of 11 and a facile chloroform recovery process by using the RadFrac model. Thus, the proposed green process with energy-conservation superiority is the vital clue for developing MMA, and provides a reference for the production of MMA-ramifications with excellent prospects.
A Novel Technology for Separating Copper, Lead and Zinc in Flotation Concentrate by Oxidizing Roasting and Leaching
Qian Zhang, Qicheng Feng, Shuming Wen, Chuanfa Cui, Junbo Liu
August 15, 2019 (v1)
Subject: Other
Keywords: copper–lead–zinc of flotation concentrate, leaching, oxidizing roasting
In this work, oxidizing roasting was combined with leaching to separate copper, lead, and zinc from a concentrate obtained by bulk flotation of a low-grade ore sourced from the Jiama mining area of Tibet. The flotation concentrate contained 7.79% Cu, 22.00% Pb, 4.81% Zn, 8.24% S, and 12.15% CaO; copper sulfide accounted for 76.97% of the copper, lead sulfide for 25.55% of the lead, and zinc sulfide for 67.66% of the zinc. After oxidizing roasting of the flotation concentrate, the S content in the roasting slag decreased to 0.22%, indicating that most sulfide in the concentrate was transformed to oxide, which was beneficial to leaching. The calcine was subjected to sulfuric acid leaching for separation of copper, lead, and zinc; i.e., copper and zinc were leached, and lead was retained in the residue. The optimum parameters of the leaching process were: a leaching temperature of 55 °C; sulfuric acid added at 828 kg/t calcine; a liquid:solid ratio of 3:1; and a leaching time of 1.5 h. Un... [more]
Lipid Isolation Process and Study on Some Molecular Species of Polar Lipid Isolated from Seed of Madhuca ellitica
Doan Lan Phuong, Tran Quoc Toan, Ly P. T. Dang, Andrey B. Imbs, Pham Quoc Long, Tran Dinh Thang, Bertrand Matthaeus, Long Giang Bach, Le Minh Bui
August 14, 2019 (v1)
Subject: Biosystems
Keywords: lipid molecular species, Madhuca ellitica, phospholipids, seeds, sulfoquinovosyldiacylglycerol, tandem high-resolution mass spectrometry
This study attempted the lipid extraction process from the seeds of Madhuca ellitica, a lipid-rich plant, and conducted a lipidomic analysis on molecular species of the obtained product. Total lipids of the crude seeds were found to contain 11.2% of polar lipids. The major fatty acids (FAs) of the polar lipids were palmitic (16:0), stearic (18:0), oleic (18:1n-9), and linoleic (18:2n-6) acids, which amounted to 28.5, 12.5, 44.8, and 13.2% of total FAs, respectively. The content and chemical structures of individual molecular species of phosphatidylglycerol (PG), phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylinositol (PI), phosphatidic acid (PA), and sulfoquinovosyldiacylglycerol (SQDG) were determined by HPLC with a tandem high-resolution mass spectrometry (HRMS). The major molecular species were 18:1/18:2 PE, 16:0/18:1 PC, 18:1/18:2 PC, 16:0/18:2 PG, 16:0/18:1 PG, 16:1/18:1 PI, 16:0/18:1 PI, 18:0/18:2 PI, 16:0/18:1 PA, 18:1/18:2 PA, 16:0/18:1 SQDG, and 18:0/18:1... [more]
The Use of Polymers in the Flotation Treatment of Wastewater
Brian Bolto, Zongli Xie
August 14, 2019 (v1)
Subject: Materials
Keywords: flotation, hydrophobic polymers, oil recovery, polyelectrolyte, polymer, Wastewater
The use of flotation for the treatment of wastewaters in general, but especially for the removal of oil, grease, general organic matter, and suspended solids, is well established as a low energy process. Polyelectrolytes (PEs) can enhance performance without adding to the solids load that occurs with inorganic additives such as alum. The bridging of pollutants and the attachment of the resulting aggregates to the air-water interface can be effectively carried out with most wastewaters. Hydrophobic modification of the PEs can be useful for difficult species. It should be applied to the flotation of polyfluoroalkyl substances, for example, as they are not amenable to economical conventional treatment. Similarly, the removal of microplastic particles from sewage effluents by flotation could be enhanced.
Identification of the Thief Zone Using a Support Vector Machine Method
Cheng Fu, Tianyue Guo, Chongjiang Liu, Ying Wang, Bin Huang
August 14, 2019 (v1)
Keywords: correlation analysis, signal-to-noise ratio, support vector machine, thief zone, tracer monitoring
Waterflooding is less effective at expanding reservoir production due to interwell thief zones. The thief zones may form during high water cut periods in the case of interconnected injectors and producers or lead to a total loss of injector fluid. We propose to identify the thief zone by using a support vector machine method. Considering the geological factors and development factors of the formation of the thief zone, the signal-to-noise ratio and correlation analysis method were used to select the relevant evaluation indices of the thief zone. The selected evaluation indices of the thief zone were taken as the input of the support vector machine model, and the corresponding recognition results of the thief zone were taken as the output of the support vector machine model. Through the training and learning of sample sets, the response relationship between thief zone and evaluation indices was determined. This method was used to identify 82 well groups in M oilfield, and the identifica... [more]
The Impact of Erythrocytes Injury on Blood Flow in Bionic Arteriole with Stenosis Segment
Donghai Li, Guiling Li, Yuanyuan Chen, Jia Man, Qingyu Wu, Mingkui Zhang, Haosheng Chen, Yu Zhang
August 14, 2019 (v1)
Subject: Biosystems
Keywords: bionic microfluidic device, erythrocyte injury, flow pattern, thrombosis
Ventricular assist device (VAD) implantation is an effective treatment for patients with end-stage heart failure. However, patients who undergo long-term application of VADs experience a series of VAD-related adverse effects including pump thrombosis, which is induced by rotate impeller-caused blood cell injury and hemolysis. Blood cell trauma-related flow patterns are the key mechanism for understanding thrombus formation. In this study, we established a new method to evaluate the blood cell damage and investigate the real-time characteristics of blood flow patterns in vitro using rheometer and bionic microfluidic devices. The variation of plasma free hemoglobin (PFH) and lactic dehydrogenase (LDH) in the rheometer test showed that high shear stress was the main factor causing erythrocyte membrane injury, while the long-term exposure of high shear stress further aggravated this trauma. Following this rheometer test, the damaged erythrocytes were collected and injected into a bionic mi... [more]
Modeling of a Double Effect Heat Transformer Operating with Water/Lithium Bromide
Itzel N. Balderas-Sánchez, J. Camilo Jiménez-García, Wilfrido Rivera
August 14, 2019 (v1)
Keywords: absorption heat transformer, COP enhancement, thermal energy upgrade, water-lithium bromide
Absorption heat transformers are effective systems for a wide variety of applications; however, their main purpose is to upgrade thermal energy from several sources at low-temperature up to a higher temperature level. In the literature, several advanced configurations for absorption heat transformers have been reported which are mainly focused on the improvement of the gross temperature lift by the use of a double absorption process; however, these systems usually offer a reduced coefficient of performance. The present study proposes a new advanced configuration of an absorption heat transformer that improves the coefficient of performance utilizing a double generation process. The operation of the new configuration was numerically modeled, and the main findings were discussed and presented emphasizing the effect of several parameters on the system performance. The highest coefficient of performance and gross temperature lift were 0.63 and 48 °C, respectively. From its comparison with... [more]
Development of a Two-Stage ESS-Scheduling Model for Cost Minimization Using Machine Learning-Based Load Prediction Techniques
Minsu Park, Jaehwi Kim, Dongjun Won, Jaehee Kim
August 14, 2019 (v1)
Keywords: bagging, energy storage system, ensemble learning, load prediction, Machine Learning, random forest, two-stage algorithm
Effective use of energy storage systems (ESS) is important to reduce unnecessary power consumption. In this paper, a day-ahead two-stage ESS-scheduling model based on the use of a machine learning technique for load prediction has been proposed for minimizing the operating cost of the energy system. The proposed algorithm consists of two stages of ESS. In the first stage, ESS is used to minimize demand charges by reducing the peak load. Then, the remaining capacity is used to reduce energy charges through arbitrage trading, thereby minimizing the total operating cost. To achieve this purpose, accurate load prediction is required. Machine learning techniques are promising methods owing to the ability to improve forecasting performance. Among them, ensemble learning is a well-known machine learning method which helps to reduce variance and prevent overfitting of a model. To predict loads, we employed bootstrap aggregating (bagging) or random forest technique-based decision trees after Ho... [more]
Impact of Thermal Radiation on Magnetohydrodynamic Unsteady Thin Film Flow of Sisko Fluid over a Stretching Surface
Abdul Samad Khan, Yufeng Nie, Zahir Shah
August 14, 2019 (v1)
Subject: Other
Keywords: HAM and numerical method, MHD, Sisko fluid, thin films, unsteady stretching sheet
The current article discussed the heat transfer and thermal radioactive of the thin liquid flow of Sisko fluid on unsteady stretching sheet with constant magnetic field (MHD). Here the thin liquid fluid flow is assumed in two dimensions. The governing time-dependent equations of Sisko fluid are modeled and reduced to Ordinary differential equations (ODEs) by use of Similarity transformation with unsteadiness non-dimensionless parameter S t . To solve the model problem, we used analytical and numerical techniques. The convergence of the problem has been shown numerically and graphically using Homotopy Analysis Method (HAM). The obtained numerical result shows that the HAM estimates of the structures is closed with this result. The Comparison of these two methods (HAM and numerical) has been shown graphically and numerically. The impact of the thermal radiation R d and unsteadiness parameter S t over thin liquid flow is discovered analytically. Moreover, to know th... [more]
Showing records 1 to 25 of 77. [First] Page: 1 2 3 4 Last
Change year: 2018 | 2019 | 2020
Change month: January | February | March | April | May | June | July | August | September | October | November | December