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Showing records 51 to 75 of 111. [First] Page: 1 2 3 4 5 Last
FFANN Optimization by ABC for Controlling a 2nd Order SISO System’s Output with a Desired Settling Time
Aydın Mühürcü
April 9, 2019 (v1)
Keywords: ABC, buck converter, control, FFANN, Modelling, Optimization, settling time
In this study, a control strategy is aimed to ensure the settling time of a 2nd order system’s output value while its input reference value is changed. Here, Feed Forward Artificial Neural Network (FFANN) nonlinear structure has been chosen as a control algorithm. In order to implement the intended control strategy, FFANN’s normalization coefficient (K), learning coefficients (ŋ), momentum coefficients (μ) and the sampling time (Ts) were optimized by Artificial Bee Colony (ABC) but FFANN’s values of weights were chosen arbitrary on start time of control system. After optimization phase, the FFANN behaves as an adaptive optimal discrete time non-linear controller that forces the system output to take the same value with the input reference for a desired settling time (ts). The success of the optimization algorithm was proved with close loop feedback control simulations on Matlab’s Simulink platform based on 2nd order transfer functions. Also, the success was proved with a 2nd order phys... [more]
Energy Analysis of the S-CO₂ Brayton Cycle with Improved Heat Regeneration
Muhammad Ehtisham Siddiqui, Khalid H. Almitani
April 9, 2019 (v1)
Keywords: energy analysis, heat exchanger effectiveness, improved heat regeneration, partial cooling, recompression Brayton cycle, supercritical carbon dioxide, thermal efficiency
Supercritical carbon dioxide (S-CO₂) Brayton cycles (BC) are promising alternatives for power generation. Many variants of S-CO₂ BC have already been studied to make this technology economically more viable and efficient. In comparison to other BC and Rankine cycles, S-CO₂ BC is less complex and more compact, which may reduce the overall plant size, maintenance, and the cost of operation and installation. In this paper, we consider one of the configurations of S-CO₂ BC called the recompression Brayton cycle with partial cooling (RBC-PC) to which some modifications are suggested with an aim to improve the overall cycle’s thermal efficiency. The type of heat source is not considered in this study; thus, any heat source may be considered that is capable of supplying temperature to the S-CO₂ in the range from 500 °C to 850 °C, like solar heaters, or nuclear and gas turbine waste heat. The commercial software Aspen HYSYS V9 (Aspen Technology, Inc., Bedford, MA, USA) is used for simulations.... [more]
Investigation of Deep Mine Shaft Stability in Alternating Hard and Soft Rock Strata Using Three-Dimensional Numerical Modeling
Xiaoming Sun, Gan Li, Chengwei Zhao, Yangyang Liu, Chengyu Miao
April 9, 2019 (v1)
Subject: Other
Keywords: alternate strata, mine shaft, relief excavation, shaft lining, surrounding rock
The problem of shaft instability has always been a major difficulty in deep mining practices. The shaft fracture has a high probability of being located near the aquifers and the soft⁻hard rock contact zone. This paper describes the deformation and stress characteristics of surrounding rock and the shaft lining under the interactive geological conditions under soft and hard rock strata in Anju coal mine, Shandong Province, China. Using the Method of Geological Strength Index (GSI ) and considering the rock-softening characteristics of water, the parameters of rock mass are calibrated. By means of the 3DEC-trigon method, the variation characteristics of surrounding rock and the shaft lining are simulated. After shaft excavation, under the condition of no support, shear failure and tensile failure occur in shallow surrounding rock shafts, and a pressure relief zone is formed. Shear failure is the main destruction mode in deep surrounding rock. Because of the different strengths of the su... [more]
High-Throughput Microfiltration Membranes with Natural Biofouling Reducer Agent for Food Processing
Panggulu Ahmad R. Utoro, Agung Sukoyo, Sandra Sandra, Nimatul Izza, Shinta Rosalia Dewi, Yusuf Wibisono
April 9, 2019 (v1)
Subject: Biosystems
Keywords: biofouling, cellulose acetate, microfiltration, mixed matrix membrane, Moringa oleifera
The effect of natural antibiotics Moringa oleifera seeds powder in cellulose acetate membranes as biofouling reducer agent was investigated. Mixed matrix membranes (MMM) were synthesized by adding 100 mesh M. oleifera seeds powder with variation of three concentrations (1 wt%, 2 wt%, and 3 wt%), into a mix polymer solution of CA (cellulose acetate) and two different solvents, i.e., DMF (dimethylformamide) and DMAc (dimethylacetamide). The synthesized membranes morphology was observed under scanning electron microscopy and from the images can be seen that the membranes made of DMAc formed rather large macrovoid as compared to DMF-based membranes. The microstructure affected the water flux through the membranes, in which the DMAc membranes provided a higher flux value and served as high-throughput microfiltration membranes. Antibacterial properties of MMM were tested using Escherichia coli adhesion onto membrane surfaces. The results showed that M. oleifera has been proven to eradicate E... [more]
Modeling Permeation through Mixed-Matrix Membranes: A Review
Gloria M. Monsalve-Bravo, Suresh K. Bhatia
April 8, 2019 (v1)
Keywords: effective medium approach, mixed-matrix membrane (MMM), particle-polymer interface, permeation modeling, simulation of MMM
Over the past three decades, mixed-matrix membranes (MMMs), comprising an inorganic filler phase embedded in a polymer matrix, have emerged as a promising alternative to overcome limitations of conventional polymer and inorganic membranes. However, while much effort has been devoted to MMMs in practice, their modeling is largely based on early theories for transport in composites. These theories consider uniform transport properties and driving force, and thus models for the permeability in MMMs often perform unsatisfactorily when compared to experimental permeation data. In this work, we review existing theories for permeation in MMMs and discuss their fundamental assumptions and limitations with the aim of providing future directions permitting new models to consider realistic MMM operating conditions. Furthermore, we compare predictions of popular permeation models against available experimental and simulation-based permeation data, and discuss the suitability of these models for pr... [more]
Numerical Investigation of the Failure Mechanism of Transversely Isotropic Rocks with a Particle Flow Modeling Method
Xu-Xu Yang, Hong-Wen Jing, Wei-Guo Qiao
April 8, 2019 (v1)
Keywords: failure mechanism, interface, particle flow modeling, transversely isotropic rocks
Transversely isotropic rocks are commonly encountered in rock engineering practices, and their strength and failure behavior is often governed by the property of anisotropy. The particle flow modeling method was utilized to investigate the failure mechanism of transversely isotropic rocks subject to uniaxial compressive loading. The details for establishing transversely isotropic rock models were first presented, and then a parametric study was carried out to look into the effect of interface properties on the failure mode and strength of transversely isotropic rock models by varying the interface dip angle. The smooth joint model was incorporated to create interfaces for the completeness of establishing transversely isotropic rock models with the particle flow modeling method. Accordingly, three failure modes observed in transversely isotropic rock models with varying dip angles were tensile failure across interfaces, shear failure along interfaces, and tensile failure along interface... [more]
Influence of Organic Ligands on the Colloidal Stability and Removal of ZnO Nanoparticles from Synthetic Waters by Coagulation
Rizwan Khan, Muhammad Ali Inam, Du Ri Park, Saba Zam Zam, Sookyo Shin, Sarfaraz Khan, Muhammad Akram, Ick Tae Yeom
April 8, 2019 (v1)
Subject: Materials
Keywords: Adsorption, coagulation, organic ligands, stability, water treatment, ZnO NPs
The large-scale production and usage of zinc oxide nanoparticles (ZnO NPs) may lead to their post-release into the aquatic environment. In this study, the effect of hydrophobic/hydrophilic organic ligands on sorption and sedimentation of ZnO NPs has been systematically investigated. In addition, the coagulation efficiency of ZnO NPs, Zn2+, dissolved organic carbon (DOC), and UV254 with varying ferric chloride (FC) dosages in synthetic waters were also evaluated. The results showed that the higher concentration of organic ligands, i.e., humic acid (HA), salicylic acid (SA), and L-cysteine (L-cys) reduced the ζ-potential and hydrodynamic diameter (HDD) of particles, which enhanced the NPs stability. The adsorption of organic ligands onto ZnO NPs was fitted with the Langmuir model, with maximum adsorption capacities of 143, 40.47, and 66.05 mg/g for HA, SA and L-cys respectively. Removal of up to 95% of ZnO NPs and Zn2+ was achieved in studied waters at the effective coagulation zone (ECR... [more]
Dynamic Modeling and Control of an Integrated Reformer-Membrane-Fuel Cell System
Pravin P. S., Ravindra D. Gudi, Sharad Bhartiya
April 8, 2019 (v1)
Keywords: auto thermal reformer, multi-loop control, palladium membrane hydrogen separation, polymer electrolyte membrane fuel cell (PEMFC)
Owing to the pollution free nature, higher efficiency and noise free operation, fuel cells have been identified as ideal energy sources for the future. To avoid direct storage of hydrogen due to safety considerations, storing hydrocarbon fuel such as methane and suitably reforming in situ for hydrogen production offers merit for further investigation. Separating the resulting hydrogen in the reformate using membrane separation can directly feed pure gas to the anode side of fuel cell for power generation. Despite the numerous works reported in literature on the dynamic and steady state modeling and analysis of reformers, membrane separation units and fuel cell systems, there has been limited work on an analysis of the integrated system consisting of all the three components. This study focuses on the mathematical modeling and analysis of the integrated reformer, membrane, fuel cell system from first principles in a dynamic framework. A multi loop control strategy is developed and imple... [more]
Time-Based Trend of Carbon Emissions in the Composting Process of Swine Manure in the Context of Agriculture 4.0
Jun-Ho Huh, Ki-Youn Kim
April 8, 2019 (v1)
Subject: Energy Policy
Keywords: Agriculture 4.0, Carbon Dioxide, carbon emission, CH4, composting process, pig production industry, real-time monitoring system, swine farm, swine manure
The widespread raising of swine in farms becomes a serious problem in terms of the emission of carbon dioxide (CO₂) and methane (CH₄). This study aims to measure concentrations of carbon dioxide and methane, which account for the largest percentage of carbon emissions, to temporally estimate the carbon emitted during the pig-manure composting process. The research subject was a farmhouse raising 3000 growing pigs and 100 mother pigs. The capacity of the composting facility for pig manure treatment was 330 m², and the daily treatment was about 6 tons. After the pig manure discharged from the pig farm was delivered to the composting facility, for the 8 days including 6 before mixing and 2 after mixing, the concentrations of CO₂ and CH₄ were measured. The result shows that the CO₂ and CH₄ concentrations in the composting facility were 1208 ± 385 ppm and 95 ± 10 ppm, respectively. In the comparison of concentrations before and after mixing at the composting facility, the values of both CO₂... [more]
Towards an Aspect-Oriented Design and Modelling Framework for Synthetic Biology
Philipp Boeing, Miriam Leon, Darren N. Nesbeth, Anthony Finkelstein, Chris P. Barnes
April 8, 2019 (v1)
Subject: Biosystems
Keywords: aspect-oriented software engineering, CAD, host context, mathematical modelling, modularity, SynBioWeaver, synthetic biology
Work on synthetic biology has largely used a component-based metaphor for system construction. While this paradigm has been successful for the construction of numerous systems, the incorporation of contextual design issues—either compositional, host or environmental—will be key to realising more complex applications. Here, we present a design framework that radically steps away from a purely parts-based paradigm by using aspect-oriented software engineering concepts. We believe that the notion of concerns is a powerful and biologically credible way of thinking about system synthesis. By adopting this approach, we can separate core concerns, which represent modular aims of the design, from cross-cutting concerns, which represent system-wide attributes. The explicit handling of cross-cutting concerns allows for contextual information to enter the design process in a modular way. As a proof-of-principle, we implemented the aspect-oriented approach in the Python tool, SynBioWeaver, which e... [more]
Basic Dye Removal with Sorption onto Low-Cost Natural Textile Fibers
George Z. Kyzas, Evi Christodoulou, Dimitrios N. Bikiaris
April 8, 2019 (v1)
Subject: Materials
Keywords: characterization, dyes, equilibrium, fibers, reuse, sorption
Over the last several years, the trend of researchers has been to use some very low-cost materials as adsorbents. For this purpose, some already commercially used bast fibers were selected as potential adsorbent materials to remove basic dye from synthetic effluents. The adsorption of basic yellow 37 dye was studied using three different bast fibers under the names of flax, ramie, and kenaf. Their morphological structure was examined using several techniques such as scanning electron microscopy (SEM), crystallinity, X-Ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), as well as those characterizations being a useful tool to propose a mechanism of the whole adsorption process. The adsorption evaluation was achieved by studying at first the pH (12) and temperature effects (25⁻55 °C). Two isotherm models (Langmuir and Freundlich) were also applied to the experimental equilibrium data revealing the superiority of ramie fibers (327, 435, and 460 mg·g−1 (25 °C) for ke... [more]
Recent Advance on Draw Solutes Development in Forward Osmosis
Qingwu Long, Yongmei Jia, Jinping Li, Jiawei Yang, Fangmei Liu, Jian Zheng, Biao Yu
April 8, 2019 (v1)
Subject: Other
Keywords: draw solutes, Energy, forward osmosis, membrane separation, regeneration
In recent years, membrane technologies have been developed to address water shortage and energy crisis. Forward osmosis (FO), as an emerging membrane-based water treatment technology, employs an extremely concentrated draw solution (DS) to draw water pass through the semi-permeable membrane from a feed solution. DS as a critical material in FO process plays a key role in determining separation performance and energy cost. Most of existing DSs after FO still require a regeneration step making its return to initial state. Therefore, selecting suitable DS with low reverse solute, high flux, and easy regeneration is critical for improving FO energy efficiency. Numerous novel DSs with improved performance and lower regeneration cost have been developed. However, none reviews reported the categories of DS based on the energy used for recovery up to now, leading to the lack of enough awareness of energy consumption in DS regeneration. This review will give a comprehensive overview on the exis... [more]
Population Balance Modeling and Opinion Dynamics—A Mutually Beneficial Liaison?
Michael Kuhn, Christoph Kirse, Heiko Briesen
April 8, 2019 (v1)
Keywords: Deffuant-Weisbuch model, interdisciplinarity, mass transfer, opinion dynamics, population balance model, social sciences
In this contribution, we aim to show that opinion dynamics and population balance modeling can benefit from an exchange of problems and methods. To support this claim, the Deffuant-Weisbuch model, a classical approach in opinion dynamics, is formulated as a population balance model. This new formulation is subsequently analyzed in terms of moment equations, and conservation of the first and second order moment is shown. Exemplary results obtained by our formulation are presented and agreement with the original model is found. In addition, the influence of the initial distribution is studied. Subsequently, the Deffuant-Weisbuch model is transferred to engineering and interpreted as mass transfer between liquid droplets which results in a more flexible formulation compared to alternatives from the literature. On the one hand, it is concluded that the transfer of opinion-dynamics problems to the domain of population balance modeling offers some interesting insights as well as stimulating... [more]
Integration of Process Modeling, Design, and Optimization with an Experimental Study of a Solar-Driven Humidification and Dehumidification Desalination System
Mohammed Alghamdi, Faissal Abdel-Hady, A. K. Mazher, Abdulrahim Alzahrani
April 8, 2019 (v1)
Keywords: dehumidification, desalination, design, experimental, humidification
Solar energy is becoming a promising source of heat and power for electrical generation and desalination plants. In this work, an integrated study of modeling, optimization, and experimental work is undertaken for a parabolic trough concentrator combined with a humidification and dehumidification desalination unit. The objective is to study the design performance and economic feasibility of a solar-driven desalination system. The design involves the circulation of a closed loop of synthetic blend motor oil in the concentrators and the desalination unit heat input section. The air circulation in the humidification and dehumidification unit operates in a closed loop, where the circulating water runs during the daytime and requires only makeup feed water to maintain the humidifier water level. Energy losses are reduced by minimizing the waste of treated streams. The process is environmentally friendly, since no significant chemical treatment is required. Design, construction, and operatio... [more]
Photocatalytic Membranes in Photocatalytic Membrane Reactors
Pietro Argurio, Enrica Fontananova, Raffaele Molinari, Enrico Drioli
April 8, 2019 (v1)
Keywords: fine chemistry, photocatalytic membrane, photocatalytic membrane reactors, wastewater treatment
The present work gives a critical overview of the recent progresses and new perspectives in the field of photocatalytic membranes (PMs) in photocatalytic membrane reactors (PMRs), thus highlighting the main advantages and the still existing limitations for large scale applications in the perspective of a sustainable growth. The classification of the PMRs is mainly based on the location of the photocatalyst with respect to the membranes and distinguished in: (i) PMRs with photocatalyst solubilized or suspended in solution and (ii) PMRs with photocatalyst immobilized in/on a membrane (i.e., a PM). The main factors affecting the two types of PMRs are deeply discussed. A multidisciplinary approach for the progress of research in PMs and PMRs is presented starting from selected case studies. A special attention is dedicated to PMRs employing dispersed TiO₂ confined in the reactor by a membrane for wastewater treatment. Moreover, the design and development of efficient photocatalytic membran... [more]
Systematic and Model-Assisted Process Design for the Extraction and Purification of Artemisinin from Artemisia annua L.—Part I: Conceptual Process Design and Cost Estimation
Maximilian Sixt, Axel Schmidt, Fabian Mestmäcker, Maximilian Johannes Huter, Lukas Uhlenbrock, Jochen Strube
April 8, 2019 (v1)
Keywords: artemisinin, cost estimation, miniplant, piloting, process design
The article summarizes a systematic process design for the extraction and purification of artemisinin from annual mugwort (Artemisia annua L.). Artemisinin serves as an anti-malaria drug, therefore, resource-efficient and economic processes for its production are needed. The process design was based on lab-scale experiments and afterwards piloted on miniplant-scale at the institute. In this part of the article, a detailed economic feasibility studies including a reference process as a benchmark the lab-scale process and the pilot-scale process is given. Relevant differences between the different scales are discussed. The details of the respective unit operations (solid-liquid extraction, liquid-liquid extraction, chromatography and crystallization) are presented in dedicated articles. The study showed that even miniaturized lab-scale experiments are able to deliver data detailed enough for scale-up calculations on a theoretical basis. To our knowledge, a comparable systematic process d... [more]
Effect of the Length-to-Width Aspect Ratio of a Cuboid Packed-Bed Device on Efficiency of Chromatographic Separation
Guoqiang Chen, Raja Ghosh
April 8, 2019 (v1)
Keywords: bioseparation, chromatography, chromatography box, cuboid packed-bed, protein, separation efficiency
In recent papers we have discussed the use of cuboid packed-bed devices as alternative to columns for chromatographic separations. These devices address some of the major flow distribution challenges faced by preparative columns used for process-scale purification of biologicals. Our previous studies showed that significant improvements in separation metrics such as the number of theoretical plates, peak shape, and peak resolution in multi-protein separation could be achieved. However, the length-to-width aspect ratio of a cuboid packed-bed device could potentially affect its performance. A systematic comparison of six cuboid packed-bed devices having different length-to-width aspect ratios showed that it had a significant effect on separation performance. The number of theoretical plates per meter in the best-performing cuboid packed-bed device was about 4.5 times higher than that in its equivalent commercial column. On the other hand, the corresponding number in the worst-performing... [more]
The Seepage Control of the Tunnel Excavated in High-Pressure Water Condition Using Multiple Times Grouting Method
Bin Gong, Yujing Jiang, Keisuke Okatsu, Xuezhen Wu, Jin Teduka, Koichi Aoki
April 8, 2019 (v1)
Subject: Other
Keywords: FLAC3D, high groundwater table, leakage control, multiple grouting, tunnel, ultramicro cement
Groundwater can cause many hazardous problems when a tunnel is excavating. Seepage force acting on the support structure and the tunnel surface cannot be negligible. Under high groundwater table condition, the seepage situation becomes more complex and it is more difficult to control the leakage of groundwater to flow into a tunnel. In the paper, a multiple times grouting method is proposed, and the mechanical deformation behavior of surrounding rock is analyzed using the FLAC3D (Fast Lagrangian Analysis of Continua in 3 Dimensions) software according to the high groundwater table condition of the Hokusatsu tunnel. The results present that multiple times grouting can control leakage and the rock deformation well, compared with one-time grouting condition in rock breaking and high water pressure area. The seepage force decrease around the tunnel and the displacement is controlled effectively. The pore pressure reduces inside the grouting zone using a new kind of grouting material, which... [more]
Mathematical Modeling of RBC Count Dynamics after Blood Loss
Manuel Tetschke, Patrick Lilienthal, Torben Pottgiesser, Thomas Fischer, Enrico Schalk, Sebastian Sager
April 8, 2019 (v1)
Subject: Biosystems
Keywords: erythropoiesis, Modelling, numerical simulation, parameter estimation, phlebotomy
The regeneration of red blood cells (RBCs) after blood loss is an individual complex process. We present a novel simple compartment model which is able to capture the most important features and can be personalized using parameter estimation. We compare predictions of the proposed and personalized model to a more sophisticated state-of-the-art model for erythropoiesis, and to clinical data from healthy subjects. We discuss the choice of model parameters with respect to identifiability. We give an outlook on how extensions of this novel mathematical model could have an important impact for personalized clinical decision support in the case of polycythemia vera (PV). PV is a slow-growing type of blood cancer, where especially the production of RBCs is increased. The principal treatment targeting the symptoms of PV is bloodletting (phlebotomy), at regular intervals that are based on personal experiences of the physicians. Model-based decision support might help to identify optimal and ind... [more]
Temporal Mixing Behavior of Conservative Solute Transport through 2D Self-Affine Fractures
Zhi Dou, Brent Sleep, Pulin Mondal, Qiaona Guo, Jingou Wang, Zhifang Zhou
April 8, 2019 (v1)
Subject: Other
Keywords: conservative solute, fractal, fracture, Mixing, roughness
In this work, the influence of the Hurst exponent and Peclet number (Pe) on the temporal mixing behavior of a conservative solute in the self-affine fractures with variable-aperture fracture and constant-aperture distributions were investigated. The mixing was quantified by the scalar dissipation rate (SDR) in fractures. The investigation shows that the variable-aperture distribution leads to local fluctuation of the temporal evolution of the SDR, whereas the temporal evolution of the SDR in the constant-aperture fractures is smoothly decreasing as a power-law function of time. The Peclet number plays a dominant role in the temporal evolution of mixing in both variable-aperture and constant-aperture fractures. In the constant-aperture fracture, the influence of Hurst exponent on the temporal evolution of the SDR becomes negligible when the Peclet number is relatively small. The longitudinal SDR can be related to the global SDR in the constant-aperture fracture when the Peclet number is... [more]
Mass Transfer in Multiphasic Gas/Liquid/Liquid Systems. KLa Determination Using the Effectiveness-Number of Transfer Unit Method
Éric Dumont
April 8, 2019 (v1)
Subject: Materials
Keywords: Absorption, effectiveness-NTU method, KLa, mass transfer, TPPB, VOC
The Effectiveness-Number of Transfer Unit method (ε-NTU method) was applied to determine the overall mass transfer coefficient, KLa, of operating gas-liquid absorbers treating Volatile Organic Compounds (VOCs). This method requires the knowledge of the operating conditions (gas flow rate, QG; liquid flow rate, QL; scrubber volume V), the measurement of gaseous concentrations at the inlet, CGin, and at the outlet, CGout, of the contactor (in order to determine the effectiveness of the absorber ε) and the calculation of the Henry coefficient of the VOC between the gas and the liquid phases (HVOC). Coupled with the “equivalent absorption capacity„ concept, the ε-NTU method was used to determine KLa of absorbers contacting a gas and a mixture of water and a Non Aqueous Phase, successfully. The method, validated from literature data for configurations countercurrent scrubbers and stirred tank reactors, could be used to simply determine the overall mass transfer coefficient of systems for wh... [more]
Adsorptive Properties of Poly(1-methylpyrrol-2-ylsquaraine) Particles for the Removal of Endocrine-Disrupting Chemicals from Aqueous Solutions: Batch and Fixed-Bed Column Studies
Augustine O. Ifelebuegu, Habibath T. Salauh, Yihuai Zhang, Daniel E. Lynch
April 8, 2019 (v1)
Subject: Materials
Keywords: Adsorption, breakthrough, EDCs, fixed-bed column, PMPS particles
The adsorptive properties of poly(1-methylpyrrol-2-ylsquaraine) (PMPS) particles were investigated in batch and column adsorption experiments as alternative adsorbent for the treatment of endocrine-disrupting chemicals in water. The PMPS particles were synthesised by condensing 3,4-dihydroxycyclobut-3-ene-1,2-dione (squaric acid) with 1-methylpyrrole in butanol. The results demonstrated that PMPS particles are effective in the removal of endocrine disrupting chemicals (EDCs) in water with adsorption being more favourable at an acidic pH, and a superior sorption capacity being achieved at pH 4. The results also showed that the removal of EDCs by the PMPS particles was a complex process involving multiple rate-limiting steps and physicochemical interactions between the EDCs and the particles. Gibbs free energy of −8.32 kJ/mole and −6.6 kJ/mol, and enthalpies of 68 kJ/mol and 43 kJ/mol, were achieved for the adsorption E2 and EE2 respectively The removal efficiencies of the EDCs by PMPS p... [more]
Model Development and Validation of Fluid Bed Wet Granulation with Dry Binder Addition Using a Population Balance Model Methodology
Shashank Venkat Muddu, Ashutosh Tamrakar, Preetanshu Pandey, Rohit Ramachandran
April 8, 2019 (v1)
Keywords: binder dissolution, fluid bed granulation, heat and mass balance, kernel development, population balance model
An experimental study in industry was previously carried out on a batch fluid bed granulation system by varying the inlet fluidizing air temperature, binder liquid spray atomization pressure, the binder liquid spray rate and the disintegrant composition in the formulation. A population balance model framework integrated with heat transfer and moisture balance due to liquid addition and evaporation was developed to simulate the fluid bed granulation system. The model predictions were compared with the industry data, namely, the particle size distributions (PSDs) and geometric mean diameters (GMDs) at various time-points in the granulation process. The model also predicted the trends for binder particle dissolution in the wetting liquid and the temperatures of the bed particles in the fluid bed granulator. Lastly, various process parameters were varied and extended beyond the region studied in the aforementioned experimental study to identify optimal regimes for granulation.
Energy and Exergy Analysis of the S-CO₂ Brayton Cycle Coupled with Bottoming Cycles
Muhammad Ehtisham Siddiqui, Aqeel Ahmad Taimoor, Khalid H. Almitani
April 8, 2019 (v1)
Keywords: combined cycle, efficiency, exergy loss, organic Rankine cycle, recompression cycle, second law efficiency, supercritical carbon dioxide
Supercritical carbon dioxide (S-CO₂) Brayton cycles (BC) are soon to be a competitive and environment friendly power generation technology. Progressive technological developments in turbo-machineries and heat exchangers have boosted the idea of using S-CO₂ in a closed-loop BC. This paper describes and discusses energy and exergy analysis of S-CO₂ BC in cascade arrangement with a secondary cycle using CO₂, R134a, ammonia, or argon as working fluids. Pressure drop in the cycle is considered, and its effect on the overall performance is investigated. No specific heat source is considered, thus any heat source capable of providing temperature in the range from 500 °C to 850 °C can be utilized, such as solar energy, gas turbine exhaust, nuclear waste heat, etc. The commercial software ‘Aspen HYSYS version 9’ (Aspen Technology, Inc., Bedford, MA, USA) is used for simulations. Comparisons with the literature and simulation results are discussed first for the standalone S-CO₂ BC. Energy analys... [more]
Shear-Flow Coupled Behavior of Artificial Joints with Sawtooth Asperities
Cheng Zhao, Rui Zhang, Qingzhao Zhang, Zhenming Shi, Songbo Yu
April 8, 2019 (v1)
Subject: Other
Keywords: artificial joint rock, hydraulic aperture, roughness, seepage pressure, shear-flow coupled test
The coupling between hydraulic and mechanical processes in rock joints has significantly influenced the properties and applications of rock mass in many engineering fields. In this study, a series of regular shear tests and shear-flow coupled tests were conducted on artificial joints with sawtooth asperities. Shear deformation, strength, and seepage properties were comprehensively analyzed to reveal the influence of joint roughness, normal stress, and seepage pressure on shear-flow coupled behavior. The results indicate that the shear failure mode, which can be divided into sliding and cutting, is dominated by joint roughness and affected by the other two factors under certain conditions. The seepage process makes a negative impact on shear strength as a result of the mutual reinforcing of offsetting and softening effects. The evolution of hydraulic aperture during the shear-flow coupled tests embodies a consistent pattern of four stages: shear contraction, shear dilation, re-contracti... [more]
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