Records Added in July 2018
Records added in July 2018
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Showing records 1 to 25 of 239. [First] Page: 1 2 3 4 5 Last
A Facile Synthesis of Hexagonal Spinel λ-MnO₂ Ion-Sieves for Highly Selective Li⁺ Adsorption
Fan Yang, Sichong Chen, Chentao Shi, Feng Xue, Xiaoxian Zhang, Shengui Ju, Weihong Xing
July 31, 2018 (v1)
Subject: Materials
Keywords: Adsorption, hydrothermal reaction, ion-sieve, LiMn2O4, λ-MnO2
Ion-sieves are a class of green adsorbent for extraction Li+ from salt lakes. Here, we propose a facile synthesis of hexagonal spinel LiMn₂O₄ (LMO) precursor under mild condition which was first prepared via a modified one-pot reduction hydrothermal method using KMnO₄ and ethanol. Subsequently, the stable spinel structured λ-MnO₂ (HMO) were prepared by acidification of LMO. The as-prepared HMO shows a unique hexagonal shape and can be used for rapid adsorption-desorption process for Li+adsorption. It was found that Li⁺ adsorption capacity of HMO was 24.7 mg·g^−1 in Li+ solution and the HMO also has a stable structure with manganese dissolution loss ratio of 3.9% during desorption process. Moreover, the lithium selectivity (α Li/Mg) reaches to 1.35 × 10³ in brine and the distribution coefficients (Kd) of Li+ is much greater than that of Mg2+. The results implied that HMO can be used in extract lithium from brine or seawater containing high ratio of magnesium and lithium.
The Fracturing Behavior of Tight Glutenites Subjected to Hydraulic Pressure
Zhichao Li, Lianchong Li, Zilin Zhang, Ming Li, Liaoyuan Zhang, Bo Huang, Chun’an Tang
July 31, 2018 (v1)
Keywords: glutenite, gravel, hydraulic fracture, numerical simulation, propagation
Tight glutenites are typically composed of heterogeneous sandstone and gravel. Due to low or ultra-low permeability, it is difficult to achieve commercial production in tight glutenites without hydraulic fracturing. Efficient exploitation requires an in-depth understanding of the fracturing behavior of these reservoirs. This paper provides a numerical method that integrates the digital image processing (DIP) technique into a numerical code rock failure process analysis (RFPA). This method could consider the glutenite heterogeneities, including intrarock and interrock heterogeneities, and the practicability is verified through two numerical tests. Two-dimensional (2D) simulations show hydraulic fractures (HFs) can penetrate or deflect to propagate along the gravels, depending on the magnitude of stress anisotropy and gravel strength. Three-dimensional (3D) simulations with the consideration of gravel distribution orientation, gravel size and axial ratio show HFs could propagate past the... [more]
Treatment of Oil-Contaminated Water by Modified Polysilicate Aluminum Ferric Sulfate
Zhaoyang You, Li Zhang, Shujuan Zhang, Yongjun Sun, Kinjal J. Shah
July 31, 2018 (v1)
Subject: Materials
Keywords: characterization, coagulant, coagulation, modified PSAFS, oily wastewater
In this experiment, a variety of inorganic materials were simply compounded with Polysilicate Aluminum Ferric Sulfate (PSAFS) to treat emulsified oil-contaminated water. Manganese sulfate (MnSO₄), magnesium sulfate (MgSO₄), and zinc sulfate (ZnSO₄) were selected as the materials to modify PSAFS in order to obtain a coagulant with good flocculation performance. During the preparation of modified PSAFS, metal manganese, magnesium, and zinc were introduced for modification, and four factors were used to optimize the best proportion of modifiers and PSAFS. The results showed that the order of demulsification and oil-removal ability is as follows: Mn-PSAFS (Mn-modified PSAFS) > Zn-PSAFS (Zn-modified PSAFS) > Mg-PSAFS (Mg-modified PSAFS) > PSAFS. Modified PSAFS was characterized by infrared spectroscopy (IR) and a Scanning Electron Microscope (SEM). In the range of 604 cm−1 to 1200 cm−1, due to the complexation reaction between metal ions and polysilicic acid, the absorption peaks of the mod... [more]
Nonlinear Flow Characteristics of a System of Two Intersecting Fractures with Different Apertures
Richeng Liu, Yujing Jiang, Hongwen Jing, Liyuan Yu
July 31, 2018 (v1)
Subject: Materials
Keywords: critical pressure difference, hydraulic aperture, mechanical aperture, Navier-Stokes equations, nonlinear flow
The nonlinear flow regimes of a crossed fracture model consisting of two fractures have been investigated, in which the influences of hydraulic gradient, surface roughness, intersecting angle, and scale effect have been taken into account. However, in these attempts, the aperture of the two crossed fractures is the same and effects of aperture ratio have not been considered. This study aims to extend their works, characterizing nonlinear flow through a system of two intersecting fractures with different apertures. First, three experiment models with two fractures having different apertures were established and flow tests were carried out. Then, numerical simulations by solving the Navier-Stokes equations were performed and the results compared with the experiment results. Finally, the effects of fracture aperture on the critical pressure difference and the ratio of hydraulic aperture to mechanical aperture were systematically analyzed. The results show that the numerical simulation res... [more]
A New Pseudo Steady-State Constant for a Vertical Well with Finite-Conductivity Fracture
Yudong Cui, Bin Lu, Mingtao Wu, Wanjing Luo
July 31, 2018 (v1)
Subject: Materials
Keywords: circular closed reservoir, conductivity-influence function, finite-conductivity fracture, normalized conductivity-influence function, Pseudo Steady-State (PPS) constant
The Pseudo Steady-State (PSS) constant bDpss is defined as the difference between the dimensionless wellbore pressure and dimensionless average pressure of a reservoir with a PSS flow regime. As an important parameter, bDpss has been widely used for decline curve analysis with Type Curves. For a well with a finite-conductivity fracture, bDpss is independent of time and is a function of the penetration ratio of facture and fracture conductivity. In this study, we develop a new semi-analytical solution for bDpss calculations using the PSS function of a circular reservoir. Based on the semi-analytical solution, a new conductivity-influence function (CIF) representing the additional pressure drop caused by the effect of fracture conductivity is presented. A normalized conductivity-influence function (NCIF) is also developed to calculate the CIF. Finally, a new approximate solution is proposed to obtain the bDpss value. This approximate solution is a fast, accurate, and time-saving calculat... [more]
Critical Hydraulic Gradient of Internal Erosion at the Soil⁻Structure Interface
Quanyi Xie, Jian Liu, Bo Han, Hongtao Li, Yuying Li, Xuanzheng Li
July 31, 2018 (v1)
Subject: Materials
Keywords: critical hydraulic gradient, internal erosion, orthogonal tests, soil–structure interface
Internal erosion at soil⁻structure interfaces is a dangerous failure pattern in earth-fill water-retaining structures. However, existing studies concentrate on the investigations of internal erosion by assuming homogeneous materials, while ignoring the vulnerable soil⁻structure-interface internal erosion in realistic cases. Therefore, orthogonal and single-factor tests are carried out with a newly designed apparatus to investigate the critical hydraulic gradient of internal erosion on soil⁻structure interfaces. The main conclusions can be draw as follows: (1) the impact order of the three factors is: degree of compaction > roughness > clay content; (2) the critical hydraulic gradient increases as the degree of compaction and clay content increases. This effect is found to be more obvious in the higher range of the degree of soil compaction and clay content. However, there exists an optimum interface roughness making the antiseepage strength at the interface reach a maximum; (3) the evo... [more]
Modeling and Optimal Design of Absorbent Enhanced Ammonia Synthesis
Matthew J. Palys, Alon McCormick, E. L. Cussler, Prodromos Daoutidis
July 31, 2018 (v1)
Keywords: ammonia synthesis, design optimization, Dynamic Modelling
Synthetic ammonia produced from fossil fuels is essential for agriculture. However, the emissions-intensive nature of the Haber⁻Bosch process, as well as a depleting supply of these fossil fuels have motivated the production of ammonia using renewable sources of energy. Small-scale, distributed processes may better enable the use of renewables, but also result in a loss of economies of scale, so the high capital cost of the Haber⁻Bosch process may inhibit this paradigm shift. A process that operates at lower pressure and uses absorption rather than condensation to remove ammonia from unreacted nitrogen and hydrogen has been proposed as an alternative. In this work, a dynamic model of this absorbent-enhanced process is proposed and implemented in gPROMS ModelBuilder. This dynamic model is used to determine optimal designs of this process that minimize the 20-year net present cost at small scales of 100 kg/h to 10,000 kg/h when powered by wind energy. The capital cost of this process sca... [more]
An Adaptive Approach Based on Resource-Awareness Towards Power-Efficient Real-Time Periodic Task Modeling on Embedded IoT Devices
Shabir Ahmad, Sehrish Malik, Israr Ullah, Muhammad Fayaz, Dong-Hwan Park, Kwangsoo Kim, DoHyeun Kim
July 31, 2018 (v1)
Keywords: embedded devices, Industry 4.0, input tasks admission control, internet of things, IoT task scheduling, real-time systems
Embedded devices are gaining popularity day by day due to the expanded use of Internet of Things applications. However, these embedded devices have limited capabilities concerning power and memory. Thus, the applications need to be tailored in such a way to perform the specified tasks within the constrained resources with the same accuracy. In Real-Time task scheduling, one of the challenging factors is the intelligent modelling of input tasks in such a way that it produces not only logically correct output within the deadline but also consumes minimum CPU power. Algorithms like Rate Monotonic and Earliest Deadline First compute hyper-period of input tasks for periodic repetition of the same set of tasks on CPU. However, at times when the tasks are not adequately modelled, they lead to an enormously high value of hyper-period which result in more CPU cycles and power consumption. Many state-of-the-art solutions are presented in this regard, but the main problem is that they limit tasks... [more]
A Multicellular Vascular Model of the Renal Myogenic Response
Maria-Veronica Ciocanel, Tracy L. Stepien, Ioannis Sgouralis, Anita T. Layton
July 31, 2018 (v1)
Keywords: gap junctions, hemodynamics, kidney, microcirculation, nonlinear model, smooth muscle
The myogenic response is a key autoregulatory mechanism in the mammalian kidney. Triggered by blood pressure perturbations, it is well established that the myogenic response is initiated in the renal afferent arteriole and mediated by alterations in muscle tone and vascular diameter that counterbalance hemodynamic perturbations. The entire process involves several subcellular, cellular, and vascular mechanisms whose interactions remain poorly understood. Here, we model and investigate the myogenic response of a multicellular segment of an afferent arteriole. Extending existing work, we focus on providing an accurate—but still computationally tractable—representation of the coupling among the involved levels. For individual muscle cells, we include detailed Ca2+ signaling, transmembrane transport of ions, kinetics of myosin light chain phosphorylation, and contraction mechanics. Intercellular interactions are mediated by gap junctions between muscle or endothelial cells. Additional inte... [more]
Effect of Cooperation on Manufacturing IT Project Development and Test Bed for Successful Industry 4.0 Project: Safety Management for Security
Sangil Park, Jun-Ho Huh
July 31, 2018 (v1)
Keywords: Bluetooth beacons, coding process, computer architecture, industrial processes, Industry 4.0, job safety, safety management, security, test bed, worker’s positional management
A new direction of the 4th industrial revolution in manufacturing and IT industries is presented in this study, wherein the manufacturing sector will be able to survive in this period by achieving rapid and flexible change through effective convergence between both industries. Under such an environment, manufacturing IT requires speedy development and a new distribution form, as well as a new method of IT project development which is adequate for that form. Thus, this study compares and analyzes the waterfall method which is being used in general manufacturing System Integration (SI) projects and the proposed DevOps method, which requires faster distribution and improvement. This study confirms that the required human resources are less than the existing SI projects when system improvement is made using the DevOps method. At the same time, this method provides much-improved quality for the same price. Therefore, future manufacturing IT projects would achieve a faster and more efficient... [more]
Applied Research for a Safer Future: Exploring Recent Job Accidents in Agriculture, Italy (2012⁻2017)
Ilaria Zambon, Andrea Piergentili, Luca Salvati, Danilo Monarca, Paulina Matyjas-Łysakowska, Andrea Colantoni
July 31, 2018 (v1)
Subject: Other
Keywords: Europe, indicators, job safety, primary sector, territorial analysis
The issue of “safe working„ has received increasing concern in recent years worldwide, especially in Europe. Several European countries developed specific strategies to ensure the safety of operators and the awareness on the potential risks that can emerge from a vast set of activities, including field activity in agriculture. Earlier investigations have lately investigated this topic, proposing quali-quantitative analysis applied to specific economic sectors. The present study focused on the working accidents occurred in agriculture over the last 6 years (2012⁻2017) in Italy. By exploring where and when injuries occurred, the socio-demographic profile of involved persons (including age, gender, nationality) and correlating these episodes to agricultural practices, the present paper reveals intrinsic patterns of safe (or unsafe) working conditions at a quite detailed spatial scale (administrative provinces) in Italy. Based on these results, training/educational programs should be plann... [more]
Simultaneous Energy and Water Optimisation in Shale Exploration
Doris Oke, Thokozani Majozi, Rajib Mukherjee, Debalina Sengupta, Mahmoud M. El-Halwagi
July 31, 2018 (v1)
Subject: Optimization
Keywords: Energy, hydraulic fracturing, membrane distillation, optimisation, Water
This work presents a mathematical model for the simultaneous optimisation of water and energy usage in hydraulic fracturing using a continuous time scheduling formulation. The recycling/reuse of fracturing water is achieved through the purification of flowback wastewater using thermally driven membrane distillation (MD). A detailed design model for this technology is incorporated within the water network superstructure in order to allow for the simultaneous optimisation of water, operation, capital cost, and energy used. The study also examines the feasibility of utilising the co-produced gas that is traditionally flared as a potential source of energy for MD. The application of the model results in a 22.42% reduction in freshwater consumption and 23.24% savings in the total cost of freshwater. The membrane thermal energy consumption is in the order of 244 × 10³ kJ/m³ of water, which is found to be less than the range of thermal consumption values reported for membrane distillation in... [more]
A Cost-Effective Redundant Digital Excitation Control System and Test Bed Experiment for Safe Power Supply for Process Industry 4.0
Hoon-Gi Lee, Jun-Ho Huh
July 31, 2018 (v1)
Keywords: Android application, Computer architecture, digital excitation control system, excitation system, job safety, Process industry 4.0, synchronous generator, system architecture
Recently, the energy demand and supply situation in the Republic of Korea (ROK) has been largely affected by the fluctuations in the energy markets around the world. Such a situation has provided a basis for requiring improvements to power plant facilities. The automatic generator voltage control systems in large-scale power plants are adopting a rapid-response static excitation method to improve the transient stability. A domestic commercially developed large-scale triple-redundant excitation system is currently operated by the 1000 MW-class nuclear power plant and its efficiency has been verified at the same site. However, such a system is too costly for smaller power plants so that a reliable and low-cost redundant digital excitation control system was developed and introduced in this study to resolve the cost problem. The system has improved its stability and reliability at the same time through double (redundant) configuration. Additionally, the system’s performance was put to the... [more]
Modelling the Nanomechanical Responses of Biofilms Grown on the Indenter Probe
Yuqing Xia, Pengfei Duan, Jinju Chen
July 31, 2018 (v1)
Keywords: biofilm, Modelling, nanoindentation
Biofilms have a profound impact on the environment, human health and industrial systems. In order to manage and control them, it is important to measure their mechanical properties intact. Therefore, it has been proposed to grow the biofilms on the atomic force microscope prior to nanoindentation tests with the same probe. However, for nanoindentation of biofilm grown on spherical indenter itself, the existing nanoindentation models become invalid. Therefore, modified models have been proposed to describe the nanoindentation response of biofilm grown on a sphere based on finite element modelling. It was found that the applicability of the models depends on the biofilm thickness and constitutive mechanical models adopted for biofilms. The models developed here would enable more reliable determination of viscoelastic properties of biofilms that grow intact on the indenter itself.
Computational Fluid Dynamics Modeling of the Catalytic Partial Oxidation of Methane in Microchannel Reactors for Synthesis Gas Production
Junjie Chen, Wenya Song, Deguang Xu
July 31, 2018 (v1)
Keywords: catalytic microreactors, Computational Fluid Dynamics, hydrogen production, microchannel reactors, partial oxidation, reaction pathway, reactor design, synthesis gas production
This paper addresses the issues related to the favorable operating conditions for the small-scale production of synthesis gas from the catalytic partial oxidation of methane over rhodium. Numerical simulations were performed by means of computational fluid dynamics to explore the key factors influencing the yield of synthesis gas. The effect of mixture composition, pressure, preheating temperature, and reactor dimension was evaluated to identify conditions that favor a high yield of synthesis gas. The relative importance of heterogeneous and homogenous reaction pathways in determining the distribution of reaction products was investigated. The results indicated that there is competition between the partial and total oxidation reactions occurring in the system, which is responsible for the distribution of reaction products. The contribution of heterogeneous and homogeneous reaction pathways depends upon process conditions. The temperature and pressure play an important role in determini... [more]
A Framework for the Development of Integrated and Computationally Feasible Models of Large-Scale Mammalian Cell Bioreactors
Parham Farzan, Marianthi G. Ierapetritou
July 31, 2018 (v1)
Keywords: bioreactor integrated modeling, bioreactor operation optimization, CFD simulation, compartmental modeling, reduced-order model
Industrialization of bioreactors has been achieved by applying several core concepts of science and engineering. Modeling has deepened the understanding of biological and physical phenomena. In this paper, the state of existing cell culture models is summarized. A framework for development of dynamic and computationally feasible models that capture the interactions of hydrodynamics and cellular activities is proposed. Operating conditions are described by impeller rotation speed, gas sparging flowrate, and liquid fill level. A set of admissible operating states is defined over discretized process parameters. The burden on a dynamic solver is reduced by assuming hydrodynamics at its fully developed state and implementation of compartmental modeling. A change in the conditions of operation is followed by hydrodynamics switching instantaneously to the steady state that would be reached under new conditions. Finally, coupling the model with optimization solvers leads to improvements in ope... [more]
A Parameter Study of the Effect of a Plasma-Induced Ozone Colour-Fading Process on Sulphur-Dyed Cotton Fabric
Dan Zhong, Yao-Hui Liu, Ngan-Ting Cheung, Chi-Wai Kan, Hong Chua
July 31, 2018 (v1)
Subject: Materials
Keywords: colour-fading, cotton fabric, ozone, plasma, sulphur dye
A plasma-induced ozone colour-fading treatment was used for treating a blue sulphur-dyed knitted cotton fabric. Since the process parameters of plasma-induced ozone colour-fading treatment are inter-related with one other, the final colour-fading results are affected. An orthogonal array testing strategy (OATS) method was used for determining the optimum conditions of the plasma-induced ozone colour-fading treatment in this study. Three process parameters used in the plasma-induced ozone colour-fading treatment, i.e., oxygen gas concentration (%), water content in fabric (%), and treatment time (minutes), were used in the optimization process. Experimental results reveal the optimum conditions for fading the colour by plasma-induced ozone colour-fading treatment are: (1) oxygen gas concentration = 70%; (2) water content in fabric = 35%; and (3) treatment time = 30 min. The order of importance of these parameters is: oxygen gas concentration > water content in fabric > treatment time. I... [more]
Void Properties in Dense Bed of Cold-Flow Fluid Catalytic Cracking Regenerator
Sung Won Kim, Sang Done Kim
July 31, 2018 (v1)
Subject: Materials
Keywords: FCC regenerator, optical fiber probe, turbulent fluidized bed, void properties
Fluid catalytic cracking (FCC) processes have been used widely in petroleum refineries. FCC regenerators play important roles for maintaining catalyst activity and supply the reaction heat. The regenerator efficiency is mainly connected to the hydrodynamics of the fluidized bed, because the gas and solid behaviors are very important factors in mass and heat transfer. The void properties, such as chord length, rising velocity, frequency, and fraction, have been determined in a large cold flow model (0.48 m-ID × 6.4 m-high) of the FCC regenerator, which was geometrically scaled down from a commercial FCC unit. The local void chord length, rising velocity, frequency, and fraction exhibit their maximum value along the radial direction of the bed. The cross-sectional mean void chord length, rising velocity, and fraction increase and the cross-sectional mean void frequency decreases with height in the bed. The variation of void properties in the FCC regenerator with turbulent fluidized bed e... [more]
Solving Materials’ Small Data Problem with Dynamic Experimental Databases
Michael McBride, Nils Persson, Elsa Reichmanis, Martha A. Grover
July 31, 2018 (v1)
Keywords: classification, database, informatics, materials, Polymers, processing
Materials processing is challenging because the final structure and properties often depend on the process conditions as well as the composition. Past research reported in the archival literature provides a valuable source of information for designing a process to optimize material properties. Typically, the issue is not having too much data (i.e., big data), but rather having a limited amount of data that is sparse, relative to a large number of design variables. The full utilization of this information via a structured database can be challenging, because of inconsistent and incorrect reporting of information. Here, we present a classification approach specifically tailored to the task of identifying a promising design region from a literature database. This design region includes all high performing points, as well as some points having poor performance, for the purpose of focusing future experiments. The classification method is demonstrated on two case studies in polymeric materia... [more]
Investigation of the Porosity Distribution, Permeability, and Mechanical Performance of Pervious Concretes
Rentai Liu, Haojie Liu, Fei Sha, Honglu Yang, Qingsong Zhang, Shaoshuai Shi, Zhuo Zheng
July 31, 2018 (v1)
Subject: Materials
Keywords: permeability coefficient, pervious concrete, pore distribution characteristics, porosity, strength
Pervious concrete is a kind of porous and permeable material for pavements and slope protection projects, etc. In this paper, a kind of pervious concrete was prepared with Portland cement, silica fume (SF), polycarboxylate superplasticizer (SP), and limestone aggregates. The performance of concrete, such as its porosity, pore distribution, permeability coefficients, and mechanical properties, were studied through laboratory tests. The volumetric porosity was measured by the water displacement method, and the planar porosity and pore size distribution were determined using image processing technology. A permeameter with a transparent sidewall and an exact sidewall sealing method were used to measure the permeability coefficients accurately. The results show that the segregation index and flow values of pastes increased with the increase of SP and water cement ratio (W/C). The measured porosity (volumetric porosity and planar porosity) of pervious concrete with a single-size aggregate wa... [more]
Deformation and Control Countermeasure of Surrounding Rocks for Water-Dripping Roadway Below a Contiguous Seam Goaf
Changqing Ma, Pu Wang, Lishuai Jiang, Changsheng Wang
July 31, 2018 (v1)
Subject: Other
Keywords: bolt support, contiguous seams, roadway deformation, water-dripping roadway
To solve the technical problem of supporting a water-dripping roadway below contiguous seams at the Tuanbai coal mine, the deformation law of surrounding rocks for the roadway was studied using Fast Lagrangian Analysis of Continua in Three Dimensions (FLAC3D) numerical simulation. Then, a mechanical model of water-dripping rock using a bolt support was established, and further, technical countermeasures to control the deformation of the roadway with a bolt and cable support are proposed. The results show that the erosion of the water dripping on the roadway was substantial and showed notable changes over time during roadway excavation and mining work. These effects caused the road to heave slightly, but it tended to be stable during roadway excavation. Moreover, the erosion of the roof and two ribs increased exponentially, and the floor heave increased with significant displacement oscillation during mining. The anchoring length of bolts and the rock weakening from water dripping had n... [more]
A Differentiable Model for Optimizing Hybridization of Industrial Process Heat Systems with Concentrating Solar Thermal Power
Matthew D. Stuber
July 31, 2018 (v1)
Keywords: concentrating solar power, concentrating solar thermal, CSP, CST, hybrid solar, industrial process heat, parabolic trough, PTC, thermal storage
A dynamic model of a concentrating solar thermal array and thermal energy storage system is presented that is differentiable in the design decision variables: solar aperture area and thermal energy storage capacity. The model takes as input the geographic location of the system of interest and the corresponding discrete hourly solar insolation data, and calculates the annual thermal and economic performance of a particular design. The model is formulated for use in determining optimal hybridization strategies for industrial process heat applications using deterministic gradient-based optimization algorithms. Both convex and nonconvex problem formulations are presented. To demonstrate the practicability of the models, they were applied to four different case studies for three disparate geographic locations in the US. The corresponding optimal design problems were solved to global optimality using deterministic gradient-based optimization algorithms. The model and optimization-based anal... [more]
Investigation on Reinforcement and Lapping Effect of Fracture Grouting in Yellow River Embankment
Jian Liu, Zhi Wan, Quanyi Xie, Cong Li, Rui Liu, Mengying Cheng, Bo Han
July 31, 2018 (v1)
Subject: Materials
Keywords: cement–silicate grout, fracture grouting, geophysical prospecting, seepage, Yellow River Embankment
Fracture grouting has been a mitigation measure widely used against seepage in the Yellow River Embankment. However, there is currently a lack of systematic investigations studying the anti-seepage effect of the fracture grouting employed in this longest river embankment in China. Therefore, in this work, laboratory and in situ experiments are carried out to investigate the reinforcement effect of fracture grouting in the Jinan section of the Yellow River Embankment. In particular, laboratory tests concentrate on studying the optimum strength improvement for cement⁻silicate grout by varying the content of backfilled fly ash and bentonite as admixtures. Mechanical strength and Scanning Electron Microscope photographs are investigated for assessing the strength and compactness improvement. Subsequently, based on the obtained optimum admixtures content, in situ grouting tests are carried out in the Jinan section of the Yellow River Embankment to evaluate the reinforcement and lapping effe... [more]
Modelling of a Naphtha Recovery Unit (NRU) with Implications for Process Optimization
Jiawei Du, William R. Cluett
July 31, 2018 (v1)
Keywords: naphtha recovery unit, Optimization, Simulation, statistical model
The naphtha recovery unit (NRU) is an integral part of the processes used in the oil sands industry for bitumen extraction. The principle role of the NRU is to recover naphtha from the tailings for reuse in this process. This process is energy-intensive, and environmental guidelines for naphtha recovery must be met. Steady-state models for the NRU system are developed in this paper using two different approaches. The first approach is a statistical, data-based modelling approach where linear regression models have been developed using Minitab® from plant data collected during a performance test. The second approach involves the development of a first-principles model in Aspen Plus® based on the NRU process flow diagram. A novel refinement to this latter model, called “withdraw and remix„, is proposed based on comparing actual plant data to model predictions around the two units used to separate water and naphtha. The models developed in this paper suggest some interesting ideas for the... [more]
Systematic Design and Evaluation of an Extraction Process for Traditionally Used Herbal Medicine on the Example of Hawthorn (Crataegus monogyna JACQ.)
Maximilian Sixt, Jochen Strube
July 31, 2018 (v1)
Keywords: harvest, Modelling, pressurized hot water extraction, Simulation, variety
Traditionally used herbal medicines are deep in the consciousness of patients for the treatment of only minor diseases by self-medication. However, manufacturers of herbal medicinal products suffer from major problems such as increasing market pressure by e.g., the food supplement sector, increasing regulations, and costs of production. Moreover, due to more stringent regulation and approval processes, innovation is hardly observed, and the methods used in process development are outdated. Therefore, this study aims to provide an approach based on modern process engineering concepts and including predictive process modelling and simulation for the extraction of traditional herbal medicines as complex extracts. The commonly used solvent-based percolation is critically assessed and compared to the so-called pressurized hot water extraction (PHWE) as a new possible alternative to replace organic solvents. In the study a systematic process design for the extraction of hawthorn (Crataegus m... [more]
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