Records Added in November 2019
Records added in November 2019
Change year: 2018 | 2019
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Showing records 1 to 25 of 115. [First] Page: 1 2 3 4 5 Last
Pressure-Relief Impact Control of Open Circuit Hydraulic Pump-Controlled Forging Press System
Xiaoming Cao, Jing Yao, Tong Sha, Yu Song
November 24, 2019 (v1)
Keywords: combined pressure-relief curve (CPRC), forging press, open circuit hydraulic pump-controlled system, pressure-relief impact
Taking the open circuit hydraulic pump-controlled forging press system as the research object, according to the problems of pressure-relief impact of this system, the pressure-relief rules, mathematic models of the energy release rules, and the flow release rules were established, and the pressure-relief performance in different stages of each pressure-relief curve was analyzed. Based on the different requirements of the pressure gradient decrease, the combined pressure-relief curve (CPRC) was proposed to realize variable-pump eccentric magnitude planning. An experimental study on the pressure-relief process with CPRC was carried out. The results show that the pressure fluctuation of the pressure-relief pipe was reduced and the suppression effect of pressure-relief impact was better than that of the single regular pressure-relief curve. When the initial pressures were 10 MPa and 15 MPa, the pressure impact of the pressure-relief tube decreased by 45.45% and 37.5%, respectively, which r... [more]
Novel 3-D T-Shaped Passive Micromixer Design with Helicoidal Flows
Mahmut Burak Okuducu, Mustafa M. Aral
November 24, 2019 (v1)
Keywords: chaotic advection, Computational Fluid Dynamics, engulfment flow, helicoidal flow, microfluidics, passive micromixer, T-micromixer, vortex flow
Laminar fluid flow and advection-dominant transport produce ineffective mixing conditions in micromixers. In these systems, a desirable fluid mixing over a short distance may be achieved using special geometries in which complex flow paths are generated. In this paper, a novel design, utilizing semi-circular ridges, is proposed to improve mixing in micro channels. Fluid flow and scalar transport are investigated employing Computational Fluid Dynamics (CFD) tool. Mixing dynamics are investigated in detail for alternative designs, injection, and diffusivity conditions. Results indicate that the convex alignment of semi-circular elements yields a specific, helicoidal-shaped fluid flow along the mixing channel which in turn enhances fluid mixing. In all cases examined, homogenous concentration distributions with mixing index values over 80% are obtained. When it is compared to the classical T-shaped micromixer, the novel design increases mixing index and mixing performance values by the fa... [more]
Techno-Economic Analysis and Physicochemical Properties of Ceiba pentandra as Second-Generation Biodiesel Based on ASTM D6751 and EN 14214
N.A.M. Jamaluddin, Teuku Meurah Indra Riayatsyah, Arridina Susan Silitonga, M. Mofijur, Abd Halim Shamsuddin, Hwai Chyuan Ong, Teuku Meurah Indra Mahlia, S.M. Ashrafur Rahman
November 24, 2019 (v1)
Subject: Biosystems
Keywords: Ceiba pentandra, non-edible oil, sensitivity analysis, techno-economic: life cycle cost
Processing biodiesel from non-edible sources of feedstock seems to be thriving in recent years. It also has also gathered more attention than in the past, mainly because the biodiesel product is renewable and emits lower pollution compared to fossil fuels. Researchers have started their work on various kinds of biodiesel product, especially from a non-edible feedstock. Non-edible feedstocks such as Ceiba pentandra show great potential in the production of biodiesel, especially in the Southeast Asia region because the plants seem to be abundant in that region. Ceiba pentandra, also known as the Kapok tree, produces hundreds of pods with a length of 15 cm (5.9 in) and diameter 2−5 cm (1−2 in). The pods consist of seeds and fluff in the surrounding areas inside the pod, which itself contains yellowish fibre, a mixture of cellulose and lignin. The seeds of Ceiba pentandra can be used as feedstock for biodiesel production. The study for Ceiba pentandra will involve techno-economic, as well... [more]
Biogas Generation through Anaerobic Digestion of Compost Leachate in Semi-Continuous Completely Stirred Tank Reactors
Alessio Siciliano, Carlo Limonti, Giulia Maria Curcio, Vincenza Calabrò
November 24, 2019 (v1)
Keywords: anaerobic digestion, biogas, compost leachate, CSTR, methane
The composting process of organic fraction of municipal solid waste, besides to the residual compost, generates a wastewater that is characterized by a high organic load. The application of anaerobic processes represents an advantageous solution for the treatment and valorization of this type of wastewater. Nevertheless, few works have been focused on the anaerobic digestion of compost leachate. To overcome this dearth, in the present paper an extensive experimental investigation was carried out to develop and analyse the anaerobic treatment of young leachate in completely stirred tank reactors (CSTR). Initially, it was defined a suitable leachate pretreatment to correct its acidic characteristics that is potentially able to inhibit methanogenic biomass activity. The pretreated leachate was fed to the digester over the start-up phase that was completed in about 40 days. During the operational period, the organic load rate (OLR) changed between 4.25 kgCOD/m3d and 38.5 kgCOD/m3d. The che... [more]
CVD Synthesis, Functionalization and CO2 Adsorption Attributes of Multiwalled Carbon Nanotubes
Shazia Shukrullah, Muhammad Yasin Naz, Norani M. Mohamed, Khalid A. Ibrahim, Nasser M. AbdEl-Salam, Abdul Ghaffar
November 24, 2019 (v1)
Subject: Materials
Keywords: CO2 adsorption capacity, fluidized bed CVD, functionalized CNTs, MWCNTs
Carbon dioxide is one of the major greenhouse gases and a leading source of global warming. Several adsorbent materials are being tested for removal of carbon dioxide (CO2) from the atmosphere. The use of multiwalled carbon nanotubes (MWCNTs) as a CO2 adsorbent material is a relatively new research avenue. In this study, Fe2O3/Al2O3 composite catalyst was used to synthesize MWCNTs by cracking ethylene gas molecules in a fluidized bed chemical vapor deposition (CVD) chamber. These nanotubes were treated with H2SO4/HNO3 solution and functionalized with 3-aminopropyl-triethoxysilane (APTS). Chemical modification of nanotubes removed the endcaps and introduced some functional groups along the sidewalls at defected sites. The functionalization of nanotubes with amine introduced carboxylic groups on the tube surface. These functional groups significantly enhance the surface wettability, hydrophilicity and CO2 adsorption capacity of MWCNTs. The CO2 adsorption capacity of as-grown and amine-fu... [more]
Using PSO Algorithm to Compensate Power Loss Due to the Aeroelastic Effect of the Wind Turbine Blade
Ying Zhao, Caicai Liao, Zhiwen Qin, Ke Yang
November 24, 2019 (v1)
Keywords: aeroelastic effect, optimization model, power loss, pretwist angle, pretwisting method
Power loss due to the aeroelastic effect of the blade is becoming an important problem of large-scale blade design. Prior work has already employed the pretwisting method to deal with this problem and obtained some good results at reference wind speed. The aim of this study was to compensate for the power loss for all of the wind speeds by using the pretwisting method. Therefore, we developed an aeroelastic coupling optimization model, which takes the pretwist angles along the blade as free variables, the maximum AEP (annual energy production) as the optimal object, and the smooth of the twist distribution as one of the constraint conditions. In this optimization model, a PSO (particle swarm optimization) algorithm is used and combined with the BEM-3DFEM (blade element momentum—three-dimensional finite element method) model. Then, the optimization model was compared with an iteration method, which was recently developed by another study and can well compensate the power loss at referen... [more]
Analysis of Air−Oil Flow and Heat Transfer inside a Grooved Rotating-Disk System
Chunming Li, Wei Wu, Yin Liu, Chenhui Hu, Junjie Zhou
November 24, 2019 (v1)
Keywords: Computational Fluid Dynamics, flow pattern, grooved disk, Nusselt number, two-phase flow, volume of fluid
An investigation on the two-phase flow field inside a grooved rotating-disk system is presented by experiment and computational fluid dynamics numerical simulation. The grooved rotating-disk system consists of one stationary flat disk and one rotating grooved disk. A three-dimensional computational fluid dynamics model considering two-phase flow and heat transfer was utilized to simulate phase distributions and heat dissipation capability. Visualization tests were conducted to validate the flow patterns and the parametric effects on the flow field. The results indicate that the flow field of the grooved rotating-disk system was identified to be an air−oil flow. A stable interface between the continuous oil phase and the two-phase area could be formed and observed. The parametric analysis demonstrated that the inter moved outwards in the radial direction, and the average oil volume fraction over the whole flow field increased with smaller angular speed, more inlet mass flow of oil, or d... [more]
Green and Facile Synthesis of Dendritic and Branched Gold Nanoparticles by Gelatin and Investigation of Their Biocompatibility on Fibroblast Cells
Quoc Khuong Vo, My Nuong Nguyen Thi, Phuong Phong Nguyen Thi, Duy Trinh Nguyen
November 24, 2019 (v1)
Subject: Biosystems
Keywords: fibroblast cells, gelatin, nanodendrites, nanostar, one-pot synthesis
In this work, gold nanostar (AuNPs) and gold nanodendrites were synthesized by one-pot and environmentally friendly approach in the presence of gelatin. Influence of gelatin concentrations and reaction conditions on the growth of branched (AuNPs) were investigated further. Interestingly, the conversion of morphology between dendritic and branched nanostructure can be attained by changing the pH value of gelatin solution. The role of gelatin as a protecting agent through the electrostatic and steric interaction was also revealed. Branched nanoparticles were characterized by surface plasmon resonance spectroscopy (SPR), transmission electron microscopy (TEM), XRD, dynamic light scattering (DLS) and zeta-potential. The chemical interaction of gelatin with branched gold nanoparticles was analyzed by Fourier transform infrared spectroscopy (FT-IT) technique. Ultraviolet visible spectroscopy results indicated the formation of branched gold nanoparticles with the maximum surface plasmon reson... [more]
Mild Hydrothermal Pretreatment of Microalgae for the Production of Biocrude with a Low N and O Content
Miriam Montero-Hidalgo, Juan J. Espada, Rosalía Rodríguez, Victoria Morales, Luis Fernando Bautista, Gemma Vicente
November 24, 2019 (v1)
Keywords: hydrothermal liquefaction, low O and N biocrude, microalgae, pretreatment
A hydrothermal pretreatment of the microalga Nannochloropsis gaditana at mild temperatures was studied in order to reduce the N and O content in the biocrude obtained by hydrothermal liquefaction (HTL). The work focused on the evaluation of temperature, reactor loading, and time (factors) to maximize the yield of the pretreated biomass and the heteroatom contents transferred from the microalga biomass to the aqueous phase (responses). The study followed the factorial design and response surface methodology. An equation for every response was obtained, which led to the accurate calculation of the operating conditions required to obtain a given value of these responses. Temperature and time are critical factors with a negative effect on the pretreated biomass yield but a positive one on the N and O recovery in the aqueous phase. The slurry concentration has to be low to increase heteroatom recovery and has to be high to maximize the pretreated microalga yields. Response equations were ob... [more]
Effects of Single-arc Blade Profile Length on the Performance of a Forward Multiblade Fan
Yikun Wei, Cunlie Ying, Jun Xu, Wenbin Cao, Zhengdao Wang, Zuchao Zhu
November 24, 2019 (v1)
Keywords: blade profile length, experimental test, forward multiblade fan, numerical simulation, performance
The effects of single-arc blade profile length on the performance of a forward multiblade fan are investigated in this paper by computational fluid dynamics and experimental measurement. The present work emphasizes that the use of a properly reduced blade inlet angle (β1A) and properly improved blade outlet angle (β2A) is to increase the length blade profile, which suggests a good physical understanding of internal complex flow characteristics and the aerodynamic performance of the fan. Numerical results indicate that the gradient of the absolute velocity among the blades in model-L (reducing the blade inlet angle and improving blade outlet angle) is clearly lower than that of the baseline model and model-S (improving the blade inlet angle and reducing blade outlet angle), where a number of secondary flows arise on the exit surface of baseline model and model-S. However, no secondary flow occurs in model-L, and the flow loss at the exit surface of the volute (scroll-shaped flow pattern... [more]
Finite Element Simulation of Multiple Slip Effects on MHD Unsteady Maxwell Nanofluid Flow over a Permeable Stretching Sheet with Radiation and Thermo-Diffusion in the Presence of Chemical Reaction
Bagh Ali, Yufeng Nie, Shahid Ali Khan, Muhammad Tariq Sadiq, Momina Tariq
November 24, 2019 (v1)
Keywords: finite element method, Maxwell fluid, MHD, multiple slip, nanofluid, thermo-diffusion
The aim of the present study is to investigate the multiple slip effects on magnetohydrodynamic unsteady Maxwell nanofluid flow over a permeable stretching sheet with thermal radiation and thermo-diffusion in the presence of chemical reaction. The governing nonlinear partial differential equations are transformed into a system of coupled nonlinear ordinary differential equations with the aid of appropriate similarity variables, and the transformed equations are then solved numerically by using a variational finite element method. The effects of various physical parameters on the velocity, temperature, solutal concentration, and nanoparticle concentration profiles as well as on the skin friction coefficient, rate of heat transfer, and Sherwood number for solutal concentration are discussed by the aid of graphs and tables. An exact solution of flow velocity, skin friction coefficient, and Nusselt number is compared with the numerical solution obtained by FEM and also with numerical resul... [more]
Improvement of the Quality of Ginkgo biloba Leaves Fermented by Eurotium cristatum as High Value-Added Feed
Minmin Zou, Xiaohan Guo, Yan Huang, Fuliang Cao, Erzheng Su, Jiahong Wang
November 24, 2019 (v1)
Subject: Biosystems
Keywords: active constituents, E. cristatum strain, ginkgo leaves, nutrients, solid-state fermentation
Ginkgo biloba leaves are well known for their high content of nutrients and bioactive substances. However, unpleasant smell and a small number of ginkgolic acids greatly reduce the utilization of the leaves. In this work, solid-state fermentation of G. biloba leaves using Eurotium cristatum was studied by investigation of the nutrient changes and its feasibility as a functional feed. E. cristatum could grow on pure G. biloba leaves and the addition of excipients could significantly improve the growth of E. cristatum. The optimal medium was with 10% (w/w) of whole G. biloba seeds and the optimized water content, pH, inoculum size and fermentation time were 45% (w/w), 4.5, 4.76 × 107 CFU/100 g wet medium, and eight days, respectively. Under the optimal conditions, the spore number increased by about 40 times. The content of flavonoids was greatly increased by 118.6%, and the protein and polyprenyl acetates (PPAs) were increased by 64.9% and 10.6%, respectively. The ginkgolic acids, ligni... [more]
Numerical Solutions of Heat Transfer for Magnetohydrodynamic Jeffery-Hamel Flow Using Spectral Homotopy Analysis Method
Asad Mahmood, Md Faisal Md Basir, Umair Ali, Mohd Shareduwan Mohd Kasihmuddin, Mohd. Asyraf Mansor
November 24, 2019 (v1)
Keywords: boundary value problems, fluid, heat transfer, Jeffery-Hamel, ordinary differential equations, partial differential equations, semi-analytical technique, spectral homotopy
This paper studies heat transfer in a two-dimensional magnetohydrodynamic viscous incompressible flow in convergent/divergent channels. The temperature profile was obtained numerically for both cases of convergent/divergent channels. It was found that the temperature profile increases with an increase in Reynold number, Prandtl number, Nusselt number and angle of the wall but decreases with an increase in Hartmann number. A relatively new numerical method called the spectral homotopy analysis method (SHAM) was used to solve the governing non-linear differential equations. The SHAM 3rd order results matched with the DTM and shooting, showing that SHAM is feasible as a technique to be used.
The Role of Blade Sinusoidal Tubercle Trailing Edge in a Centrifugal Pump with Low Specific Speed
Bowen Li, Xiaojun Li, Xiaoqi Jia, Feng Chen, Hua Fang
November 24, 2019 (v1)
Keywords: blade trailing edge, centrifugal pump, pressure pulsations, sinusoidal tubercle
Pressure pulsations may cause high-amplitude vibrations during the process of a centrifugal pump. The trailing edge shape of the blade has a critical influence on the pump’s pressure fluctuation and hydraulic characterization. In this paper, inspired by the humpback whale flipper, the authors research the impact of applying the sinusoidal tubercles to the blade suction side of the trailing edge. Numerical calculation and experiments are carried out to investigate the impact of the trailing edge shape on the pressure pulsations and performance of a centrifugal pump with low specific speed. Two designed impellers are tested, one is a sinusoidal tubercle trailing edge (STTE) impeller and the other is the original trailing edge (OTE) prototype. The detailed study indicates that the sinusoidal tubercle trailing edge (STTE) reduces pressure pulsation and enhances hydraulic performance. In the volute tongue region, the pressure pulsation amplitudes of STTE at fBPF decrease significantly. The... [more]
The Direct Speed Control of Pmsm Based on Terminal Sliding Mode and Finite Time Observer
Yao Wang, HaiTao Yu, Zhiyuan Che, Yuchen Wang, Yulei Liu
November 24, 2019 (v1)
Keywords: finite-time observer (FTO), mismatched/matched disturbance/uncertainties, non-singular terminal sliding mode control (NTSMC), permanent magnet synchronous motor (PMSM)
A non-singular terminal sliding mode control based on finite time observer is designed to achieve speed direct control for the permanent magnet synchronous motor (PMSM) drive system. Speed and current are regulated in one loop under the non-cascade structure, taking place of the cascade structure control method in the vector control of PMSM. Based on the second-order speed function of the PMSM, the disturbance and parameters uncertainties are estimated by the designed finite time observer (FTO), and compensate to the drive system. The estimated value of the finite time observer will converge to the actual disturbance value in a finite time. A second-order non-singular terminal sliding mode controller is proposed to realize the speed and current single-loop, which can track the reference speed and reference current in a finite time. Rigorous stability analysis is established. Comparative results verified that the proposed method has faster speed tracking performance and disturbance reje... [more]
Rainwater Harvesting Potential and Utilization for Artificial Recharge of Groundwater Using Recharge Wells
Fiaz Hussain, Riaz Hussain, Ray-Shyan Wu, Tanveer Abbas
November 24, 2019 (v1)
Subject: Energy Policy
Keywords: artificial recharge wells, Lahore city, RWH, urban inundation
This study devised a practical solution to mitigate urban inundation and artificial recharge of groundwater using recharge wells which is the most viable surface runoff rainwater harvesting (RWH) technique in urban areas. The Rainwater Harvesting Pilot Project at Gaddafi Stadium Lahore was established to deal with urban flooding, artificial recharge of groundwater, and to avoid the mixing of rainwater in municipal sewerage. The study showed that Lahore city has great RWH potential from critical ponding roads that can be utilized to recharge the Lahore aquifer. With that ratio of recharge, the groundwater level can rise to 3.54 ft after every monsoon period if the same recharge wells structure are used, which is a key to groundwater sustainability in Lahore city. Moreover, the maximum recharging capacity of wells was 29.32 m3/h with satisfactory performance. Both recharge wells cleared the ponding volume within 3 to 3.5 h after the rainfall stopped. The filter media performance was also... [more]
Water Treatment Using Metallic Iron: A Tutorial Review
Rui Hu, Willis Gwenzi, Viviane Raïssa Sipowo-Tala, Chicgoua Noubactep
November 24, 2019 (v1)
Subject: Materials
Keywords: iron corrosion products, laboratory experiments, pilot tests, removal mechanisms, water treatment, zero-valent iron
Researchers and engineers using metallic iron (Fe0) for water treatment need a tutorial review on the operating mode of the Fe0/H2O system. There are few review articles attempting to present systematic information to guide proper material selection and application conditions. However, they are full of conflicting reports. This review seeks to: (i) Summarize the state-of-the-art knowledge on the remediation Fe0/H2O system, (ii) discuss relevant contaminant removal mechanisms, and (iii) provide solutions for practical engineering application of Fe0-based systems for water treatment. Specifically, the following aspects are summarized and discussed in detail: (i) Fe0 intrinsic reactivity and material selection, (ii) main abiotic contaminant removal mechanisms, and (iii) relevance of biological and bio-chemical processes in the Fe0/H2O system. In addition, challenges for the design of the next generation Fe0/H2O systems are discussed. This paper serves as a handout to enable better practic... [more]
Numerical Simulation Study of Heavy Oil Production by Using In-Situ Combustion
Zhao Yang, Shuang Han, Hongji Liu
November 24, 2019 (v1)
Keywords: heavy oil reservoir, in-situ combustion, numerical simulation, oil recovery
An in-situ combustion method is an effective method to enhance oil recovery with high economic recovery rate, low risk, fast promotion and application speed. Currently, in-situ combustion technique is regarded as the last feasible thermal recovery technology to replace steam injection in the exploitation of bitumen sands and heavy oil reservoirs. However, the oil-discharging mechanism during the in-situ combustion process is still not clearly understood. In this paper, the in-situ combustion process has been numerically simulated based on the Du 66 block. The effect of production parameters (huff and puff rounds, air injection speed, and air injection temperature) and geological parameters (bottom water thickness, stratigraphic layering, permeability ratio, and formation thickness) on the heavy oil recovery have been comprehensively analyzed. Results show that the flooding efficiency is positively correlated with the thickness of the bottom water, and negatively correlated with the for... [more]
Water-In-Oil Emulsions through Porous Media and the Effect of Surfactants: Theoretical Approaches
Josue F. Perez-Sanchez, Nancy P. Diaz-Zavala, Susana Gonzalez-Santana, Elena F. Izquierdo-Kulich, Edgardo J. Suarez-Dominguez
November 24, 2019 (v1)
Keywords: emulsions in porous media, MMH in asphaltenes, pressure drop, surfactant activity
The most complex components in heavy crude oils tend to form aggregates that constitute the dispersed phase in these fluids, showing the high viscosity values that characterize them. Water-in-oil (W/O) emulsions are affected by the presence and concentration of this phase in crude oil. In this paper, a theoretical study based on computational chemistry was carried out to determine the molecular interaction energies between paraffin−asphaltenes−water and four surfactant molecules to predict their effect in W/O emulsions and the theoretical influence on the pressure drop behavior for fluids that move through porous media. The mathematical model determined a typical behavior of the fluid when the parameters of the system are changed (pore size, particle size, dispersed phase fraction in the fluid, and stratified fluid) and the viscosity model determined that two of the surfactant molecules are suitable for applications in the destabilization of W/O emulsions. Therefore, an experimental st... [more]
Optimization of Tubular Microalgal Photobioreactors with Spiral Ribs under Single-Sided and Double-Sided Illuminations
Yuling Lei, Jing Wang, Jing Wu
November 24, 2019 (v1)
Keywords: light/dark boundary, light/dark cycle frequency, orthogonal test, tubular microalgal photobioreactor, vortex
Microalgae can be raw materials for the production of clean energy and have great potential for development. The design of the microalgal photobioreactor (PBR) affects the mixing of the algal suspension and the utilization efficiency of the light energy, thereby affecting the high-efficiency cultivation of the microalgae. In this study, a spiral rib structure was introduced into a tubular microalgal PBR to improve the mixing performance and the light utilization efficiency. The number of spiral ribs, the inclination angle, and the velocity of the algal suspension were optimized for single-sided and double-sided parallel light illuminations with the same total incident light intensity. Next, the optimization results under the two illumination modes were compared. The results showed that the double-sided illumination did not increase the average light/dark (L/D) cycle frequency of the microalgae particles, but it reduced the efficiency of the L/D cycle enhancement. This outcome was analy... [more]
Extended State Observer-Based Predictive Speed Control for Permanent Magnet Linear Synchronous Motor
Yao Wang, Haitao Yu, Zhiyuan Che, Yuchen Wang, Cheng Zeng
November 24, 2019 (v1)
Keywords: composite control, extended state observer (ESO), permanent magnet linear synchronous motor (PMLSM), predictive function control (PFC), robustness
Combining the feedback of predictive function control and the feedforward of extended state observer, a composite control strategy is proposed for the permanent magnet linear synchronous motor (PMLSM). The mathematical model of the PMLSM vector control system is established based on the basic structure and operation mechanism of PMLSM. Then, a speed regulator based on predictive function control (PFC) is designed to improve the speed tracking performance of the PMLSM drive system. The state and disturbance of the PMLSM system estimated by the extended state observer (ESO) transferred to the PMLSM drive system, and the robustness of the drive system will be improved. Comparative simulation and experiment results show that the proposed method has better speed tracking performance and disturbance rejection property.
Nanoemulsions: Factory for Food, Pharmaceutical and Cosmetics
Nor Azrini Nadiha Azmi, Amal A. M. Elgharbawy, Shiva Rezaei Motlagh, Nurhusna Samsudin, Hamzah Mohd. Salleh
November 24, 2019 (v1)
Keywords: cosmetics, homogenization, nanoemulsions (NEs), oil-in-water, pharmaceutical, ultrasonication
Nanotechnology, particularly nanoemulsions (NEs), have gained increasing interest from researchers throughout the years. The small-sized droplet with a high surface area makes NEs important in many industries. In this review article, the components, properties, formation, and applications are summarized. The advantages and disadvantages are also described in this article. The formation of the nanosized emulsion can be divided into two types: high and low energy methods. In high energy methods, high-pressure homogenization, microfluidization, and ultrasonic emulsification are described thoroughly. Spontaneous emulsification, phase inversion temperature (PIT), phase inversion composition (PIC), and the less known D-phase emulsification (DPE) methods are emphasized in low energy methods. The applications of NEs are described in three main areas which are food, cosmetics, and drug delivery.
Air-Core−Liquid-Ring (ACLR) Atomization Part II: Influence of Process Parameters on the Stability of Internal Liquid Film Thickness and Resulting Spray Droplet Sizes
Marc O. Wittner, Miguel A. Ballesteros, Frederik J. Link, Heike P. Karbstein, Volker Gaukel
November 24, 2019 (v1)
Keywords: ACLR, atomization, Computational Fluid Dynamics, high viscosity, liquid film thickness, two phase flow
Air-core−liquid-ring (ACLR) atomization presents a specific type of internal mixing pneumatic atomization. It can be used for disintegration of high viscous feed liquids into small droplets at relatively low gas consumptions. However, the specific principle of ACLR atomization is still under research and no guidelines for process and atomizer design are available. Regarding literature on pre-filming atomizers, it can be hypothesized for ACLR atomization that the liquid film thickness inside the exit orifice of the atomizer, as well as the resulting spray droplet sizes decrease with increasing air-to-liquid ratio (ALR) and decreasing feed viscosity. In this study, the time dependent liquid film thickness inside the exit orifice of the atomizer was predicted by means of computational fluid dynamics (CFD) analysis. Results were compared to high speed video images and correlated to measured spray droplet sizes. In conclusion, the hypothesis could be validated by simulation and experimental... [more]
Explicit Residence Time Distribution of a Generalised Cascade of Continuous Stirred Tank Reactors for a Description of Short Recirculation Time (Bypassing)
Peter Toson, Pankaj Doshi, Dalibor Jajcevic
November 24, 2019 (v1)
Keywords: bypassing, continuous manufacturing, continuous stirred tank reactor, Fourier analysis, residence time distribution
The tanks-in-series model (TIS) is a popular model to describe the residence time distribution (RTD) of non-ideal continuously stirred tank reactors (CSTRs) with limited back-mixing. In this work, the TIS model was generalised to a cascade of n CSTRs with non-integer non-negative n. The resulting model describes non-ideal back-mixing with n > 1. However, the most interesting feature of the n-CSTR model is the ability to describe short recirculation times (bypassing) with n < 1 without the need of complex reactor networks. The n-CSTR model is the only model that connects the three fundamental RTDs occurring in reactor modelling by variation of a single shape parameter n: The unit impulse at n→0, the exponential RTD of an ideal CSTR at n = 1, and the delayed impulse of an ideal plug flow reactor at n→∞. The n-CSTR model can be used as a stand-alone model or as part of a reactor network. The bypassing material fraction for the regime n < 1 was analysed. Finally, a Fourier analysis o... [more]
A Comparison of Clustering and Prediction Methods for Identifying Key Chemical−Biological Features Affecting Bioreactor Performance
Yiting Tsai, Susan A. Baldwin, Lim C. Siang, Bhushan Gopaluni
November 24, 2019 (v1)
Keywords: bioinformatics, Machine Learning, statistics
Chemical−biological systems, such as bioreactors, contain stochastic and non-linear interactions which are difficult to characterize. The highly complex interactions between microbial species and communities may not be sufficiently captured using first-principles, stationary, or low-dimensional models. This paper compares and contrasts multiple data analysis strategies, which include three predictive models (random forests, support vector machines, and neural networks), three clustering models (hierarchical, Gaussian mixtures, and Dirichlet mixtures), and two feature selection approaches (mean decrease in accuracy and its conditional variant). These methods not only predict the bioreactor outcome with sufficient accuracy, but the important features correlated with said outcome are also identified. The novelty of this work lies in the extensive exploration and critique of a wide arsenal of methods instead of single methods, as observed in many papers of similar nature. The results show... [more]
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