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Showing records 1 to 25 of 126. [First] Page: 1 2 3 4 5 Last
Phenolic Compounds Extraction of Arbutus unedo L.: Process Intensification by Microwave Pretreatment
Agostinho M. R. C. Alexandre, Ana A. Matias, Maria Rosário Bronze, Maria Jose Cocero, Rafael Mato
May 22, 2020 (v1)
Keywords: Arbutus unedo, microwave pretreatment, phenolic compounds, Process Intensification
Arbutus unedo L., commonly known as the strawberry-tree fruit, is an endemic species of the Mediterranean flora. Microwave extraction technology has been considered as a fast and “green” method for the production of extracts rich in bioactive compounds, although the energy consumption is high. To overcome this bottleneck, microwave was used as a pretreatment procedure in short time periods. This technique promotes the burst of intracellular vacuoles leading to an increase in the lixiviation of phenolic compounds. Different approaches were tested, namely a solvent-free irradiation (SFI), a solvent-assisted irradiation (SAI) and a pressurized solvent-assisted irradiation (PSAI). After irradiation, a solid−liquid extraction procedure was performed using a mixture of water and ethanol. A kinetic evaluation of the total phenolic content (TPC) was performed using the Folin−Ciocalteu method. For the total anthocyanin content, a UV-spectrophotometric method was used. HPLC-UV and LC-MS were use... [more]
Adsorption and Separation of the H2O/H2SO4 and H2O/C2H5OH Mixtures: A Simulated and Experimental Study
Jesse Y. Rumbo Morales, Alan F. Perez Vidal, Gerardo Ortiz Torres, Alexis U. Salas Villalobo, Felipe de J. Sorcia Vázquez, Jorge A. Brizuela Mendoza, Miguel De-la-Torre, Jorge S. Valdez Martínez
May 22, 2020 (v1)
Subject: Materials
Keywords: heat and chemical treatment, natural and synthetic zeolites, pressure swing adsorption process
Adsorption processes are characterized by their kinetics and equilibrium isotherms described by mathematical models. Nowadays, adsorption with molecular sieves is a method used to separate certain elements or molecules from a mixture and produce hydrogen, nitrogen, oxygen, ethanol, or water treatment. This study had two main objectives. The first one was focused on the use of different natural (Clinoptilolite-S.L. Potosi, Clinoptilolite-Puebla, and Heulandite-Sonora) and synthetic (Zeolite Type 3A) adsorbents to separate the mixtures H 2 O / H 2 S O 4 and H 2 O / C 2 H 5 O H . It was determined that both Zeolite Type-3A and Heulandite-Sonora have greater adsorption capacity in a shorter time compared with the Clinoptilolites at different temperatures. The second objective was the simulation of a pressure swing adsorption process to dehydrate ethanol using the parameters obtained from Zeolite Type 3A (with maximum adsorption capacity). Several configurations w... [more]
Data-Driven Robust Optimal Operation of Thermal Energy Storage in Industrial Clusters
Mandar Thombre, Zawadi Mdoe, Johannes Jäschke
May 22, 2020 (v1)
Keywords: data-driven, energy-efficiency, industrial clusters, robust model predictive control, thermal energy storage, uncertainty
Industrial waste heat recovery is an attractive option having the simultaneous benefits of reducing energy costs as well as carbon emissions. In this context, thermal energy storage can be used along with an optimal operation strategy like model predictive control (MPC) to realize significant energy savings. However, conventional control methods offer little robustness against uncertainty in terms of daily operation, where supply and demand of energy in the cluster can vary significantly from their predicted profiles. A major concern is that ignoring the uncertainties in the system may lead to the system violating critical constraints that affect the quality of the end-product of the participating processes. To this end, we present a method to make optimal energy storage and discharge decisions, while rigorously handling this uncertainty. We employ multivariate data analysis on historical industrial data to implement a multistage nonlinear MPC scheme based on a scenario-tree formulatio... [more]
Phenomenological Analysis of Thermo-Mechanical-Chemical Properties of GFRP during Curing by Means of Sensor Supported Process Simulation
Robert Hein, Robert Prussak, Jochen Schmidt
May 22, 2020 (v1)
Keywords: dielectric sensors, fiber bragg grating, process simulation, process-induced distortions, process-induced strains, reaction kinetic, residual stresses, viscoelasticity
Inherent process-induced deformations (PID) and residual stresses impede the application of composite parts. PID lead to a geometrical mismatch in assemblies and require subsequent work for tolerance compensation. Unknown residual stresses cause overweighted structures resulting from unnecessary high safety factors. To counteract the deformations, the tool design needs to be modified until the component geometry meets the specifications. This process is mostly carried out empirically and is time and cost intensive. To improve the efficiency of the development process, an in-deep comprehension of the manufacturing processes is mandatory. Therefore, experimental and simulation-based methods are increasingly applied and enhanced. The object of this work is to investigate the development of process-induced strains as well as the material behaviour during the manufacturing for a GFRP plate. The process-induced strains are monitored by optical fiber Bragg grating (FBG) sensors. The change of... [more]
Distributed Optimal Frequency Regulation for Multiple Distributed Power Generations with an Event-Triggered Communication Mechanism
Shiyun Xu, Huadong Sun, Bing Zhao, Jun Yi, Shengxuan Weng, Jianbo Chen, Chunxia Dou
May 22, 2020 (v1)
Keywords: distributed control, event-triggered mechanism, microgrid, multiple power generations, optimal frequency regulation
This paper studied the distributed optimal frequency regulation for multiple power generations in an isolated microgrid under limited communication resource. The event-triggered mechanism is introduced in the construction of the regulation algorithm. Each power generation in the microgrid only transmits its own information to its neighbors through a communication network when the event-triggered condition is satisfied, and the communication burden can be reduced significantly. Moreover, Zeno behavior is excluded to make the event-triggered regulation algorithm reasonable and realistic for practical microgrids. The proposed regulation method can restore the frequency and retain the economic efficiency simultaneously when some disturbances occur in isolated microgrids. The experimental result shows the effectiveness of the theoretical method.
The Influence of Freezing and Thawing on the Yield and Energy Consumption of the Celeriac Juice Pressing Process
Rafał Nadulski, Zbigniew Kobus, Tomasz Guz
May 22, 2020 (v1)
Keywords: celery root, freezing, juice properties, pressing, specific energy, thawing, yield
The aim of this study is to indicate the influence of pretreatment, consisting of grinding vegetables and then freezing and thawing the raw material before pressing on the process efficiency and quality of obtained juice. The subject of the research was celeriac root (Apium graveolens L) of the Edward variety. Juice pressing was carried out in a laboratory basket press. The pressing yield and specific energy were values characterizing the pressing process, while pH and the extracted content in the juice were used to assess the juice quality. The experiment was performed according to three procedures. In each of them, the ground celeriac root (pulp or chips) was initially pretreated through freezing and thawing and then pressed twice. Among the examined methods of obtaining juice, the most beneficial method was pressing juice from the pulp, then freezing and thawing the pomace obtained in the first cycle, and finally, pressing the pomace. It is an energy-optimal method and guarantees a... [more]
Metal−Organic Framework Thin Films: Fabrication, Modification, and Patterning
Yujing Zhang, Chih-Hung Chang
May 22, 2020 (v1)
Subject: Materials
Keywords: fabrication, metal–organic framework, patterning, thin film
Metal−organic frameworks (MOFs) have been of great interest for their outstanding properties, such as large surface area, low density, tunable pore size and functionality, excellent structural flexibility, and good chemical stability. A significant advancement in the preparation of MOF thin films according to the needs of a variety of applications has been achieved in the past decades. Yet there is still high demand in advancing the understanding of the processes to realize more scalable, controllable, and greener synthesis. This review provides a summary of the current progress on the manufacturing of MOF thin films, including the various thin-film deposition processes, the approaches to modify the MOF structure and pore functionality, and the means to prepare patterned MOF thin films. The suitability of different synthesis techniques under various processing environments is analyzed. Finally, we discuss opportunities for future development in the manufacturing of MOF thin films.
Eucalyptus Kraft Lignin as an Additive Strongly Enhances the Mechanical Resistance of Tree-Leaf Pellets
Leonardo Clavijo, Slobodan Zlatanovic, Gerd Braun, Michael Bongards, Andrés Dieste, Stéphan Barbe
May 22, 2020 (v1)
Subject: Materials
Keywords: additive, biofuel, circular economy, eucalyptus kraft lignin, pellet, tree leaf
Pelleted biomass has a low, uniform moisture content and can be handled and stored cheaply and safely. Pellets can be made of industrial waste, food waste, agricultural residues, energy crops, and virgin lumber. Despite their many desirable attributes, they cannot compete with fossil fuel sources because the process of densifying the biomass and the price of the raw materials make pellet production costly. Leaves collected from street sweeping are generally discarded in landfills, but they can potentially be valorized as a biofuel if they are pelleted. However, the lignin content in leaves is not high enough to ensure the physical stability of the pellets, so they break easily during storage and transportation. In this study, the use of eucalyptus kraft lignin as an additive in tree-leaf pellet production was studied. Results showed that when 2% lignin is added the abrasion resistance can be increased to an acceptable value. Pellets with added lignin fulfilled all requirements of Europ... [more]
Green Separation and Extraction Processes: Part I
George Z. Kyzas, Kostas A. Matis
May 22, 2020 (v1)
Supercritical fluid extraction comprises a known technology applied to obtain volatile compounds from flowers, i [...]
Effects of Low-Temperature Drying with Intermittent Gaseous Chlorine Dioxide Treatment on Texture and Shelf-Life of Rice Cakes
Timilehin Martins Oyinloye, Won Byong Yoon
May 22, 2020 (v1)
Subject: Other
Keywords: cutting analysis, image processing, intermittent ClO2 drying, microbial growth model
We investigated the effect of chlorine dioxide (ClO2) under low temperature drying to suppress rice cake stickiness during the cutting process by initiating the onset of retrogradation until the stickiness is minimized for shelf-life extension. The intermittent ClO2 application at low-temperature drying was conducted at 10 °C for different drying periods (0, 6, 12, 18, and 24 h). Texture analysis showed significant differences with increasing values of hardness (901.39 ± 53.87 to 12,653 ± 1689.35 g) and reduced values of modified adhesiveness (3614.37 ±578.23 to 534.81 ± 89.37 g). The evaluation of rice cake stickiness during the cutting process revealed an optimum drying period of 18 h with no significant difference (p ≤ 0.05) compared to the 24 h drying process. Microbial contamination during the drying process increased, with microbial load from 6.39 ± 0.37 to 7.94 ± 0.29 CFU/g. Intermittent ClO2 application at 22 ppm successfully reduced the microbial load by 63% during drying proc... [more]
Journey Making: Applying PSE Principles to Complex Curriculum Designs
Ian Cameron, Greg Birkett
May 22, 2020 (v1)
Subject: Education
Keywords: curricula, design, higher education, process systems engineering, visualization
Since the 1950s, Process Systems Engineering (PSE) concepts have traditionally been applied to the process industries, with great effect and with significant benefit. However, the same general approaches and principles in designing complex process designs can be applied to the design of higher education (HE) curricula. Curricula represent intended learning journeys, these being similar to the design of process flowsheets. In this paper, we set out the formal framework and concepts that underlie the challenges in design of curricula. The approaches use generic and fundamental concepts that can be applied by any discipline to curriculum design. We show how integration of discipline-specific concepts, across time and space, can be combined through design choices, to create learning journeys for students. These concepts are captured within a web-based design tool that permits wide choices for designers to build innovative curricula. The importance of visualization of curricula is discussed... [more]
Preparation of Nano-Porous Carbon-Silica Composites and Its Adsorption Capacity to Volatile Organic Compounds
Lipei Fu, Jiahui Zhu, Weiqiu Huang, Jie Fang, Xianhang Sun, Xinya Wang, Kaili Liao
May 22, 2020 (v1)
Subject: Materials
Keywords: Adsorption, carbon-silica composites, dynamic adsorption, regenerating property, volatile organic compounds (VOCs)
Carbon-silica composites with nanoporous structures were synthesized for the adsorption of volatile organic compounds (VOCs), taking tetraethyl orthosilicate (TEOS) as the silicon source and activated carbon powder as the carbon source. The preparation conditions were as follows: the pH of the reaction system was 5.5, the hydrophobic modification time was 50 h, and the dosage of activated carbon was 2 wt%. Infrared spectrum analysis showed that the activated carbon was dispersed in the pores of aerogel to form the carbon-silica composites material. The static adsorption experiments, dynamic adsorption-desorption experiments, and regeneration experiments show that the prepared carbon-silica composites have microporous and mesoporous structures, the adsorption capacity for n-hexane is better than that of conventional hydrophobic silica gel, and the desorption performance is better than that of activated carbon. It still has a high retention rate of adsorption capacity after multiple adso... [more]
Machine Learning-Based Prediction of a BOS Reactor Performance from Operating Parameters
Alireza Rahnama, Zushu Li, Seetharaman Sridhar
May 22, 2020 (v1)
Keywords: Artificial Intelligence, BOS reactor, Machine Learning, neural network, steelmaking
A machine learning-based analysis was applied to process data obtained from a Basic Oxygen Steelmaking (BOS) pilot plant. The first purpose was to identify correlations between operating parameters and reactor performance, defined as rate of decarburization (dc/dt). Correlation analysis showed, as expected a strong positive correlation between the rate of decarburization (dc/dt) and total oxygen flow. On the other hand, the decarburization rate exhibited a negative correlation with lance height. Less obviously, the decarburization rate, also showed a positive correlation with temperature of the waste gas and CO2 content in the waste gas. The second purpose was to train the pilot-plant dataset and develop a neural network based regression to predict the decarburization rate. This was used to predict the decarburization rate in a BOS furnace in an actual manufacturing plant based on lance height and total oxygen flow. The performance was satisfactory with a coefficient of determination o... [more]
Distributed Secondary Control for Islanded Microgrids Cluster Based on Hybrid-Triggered Mechanisms
Shengxuan Weng, Yusheng Xue, Jianbo Luo, Yanman Li
May 22, 2020 (v1)
Keywords: distributed control, frequency restoration, islanded microgrids cluster, power sharing, triggered mechanism
Considering the communication resources limitation, the hybrid-triggered mechanism based distributed control of islanded microgrids cluster is proposed, which can restore the frequency to the rated value and realize the active power sharing when the disturbance occurs. The hybrid-triggered mechanism consists of the self- and event-triggered mechanisms, which are configured at each leader and follower distributed generation to determine the inter-microgrids and intra-microgrid information transmission, respectively. The communication burdens can be sharply reduced since the information is transmitted aperiodically only when the proposed triggering conditions are satisfied under the hybrid-triggered mechanism. Moreover, Zeno behavior is analyzed to be avoided to make the hybrid-triggered mechanism reasonable and practicable for practical islanded microgrids cluster. The simulation verifies the effectiveness of theoretical results.
Available Technologies and Materials for Waste Cooking Oil Recycling
Alberto Mannu, Sebastiano Garroni, Jesus Ibanez Porras, Andrea Mele
May 22, 2020 (v1)
Subject: Materials
Keywords: biodiesel, biolubricant, recycling, vegetable oil degumming, vegetable oil filtration, waste cooking oil
Recently, the interest in converting waste cooking oils (WCOs) to raw materials has grown exponentially. The driving force of such a trend is mainly represented by the increasing number of WCO applications, combined with the definition, in many countries, of new regulations on waste management. From an industrial perspective, the simple chemical composition of WCOs make them suitable as valuable chemical building blocks, in fuel, materials, and lubricant productions. The sustainability of such applications is sprightly related to proper recycling procedures. In this context, the development of new recycling processes, as well as the optimization of the existing ones, represents a priority for applied chemistry, chemical engineering, and material science. With the aim of providing useful updates to the scientific community involved in vegetable oil processing, the current available technologies for WCO recycling are herein reported, described, and discussed. In detail, two main types of... [more]
A Molecular Force Field-Based Optimal Deployment Algorithm for UAV Swarm Coverage Maximization in Mobile Wireless Sensor Network
Xi Wang, Guan-zheng Tan, Fan-Lei Lu, Jian Zhao, Yu-si Dai
May 22, 2020 (v1)
Keywords: coverage maximization, deployment algorithm, molecular force, MWSN, UAV swarm
In the mobile wireless sensor network (MWSN) field, there exists an important problem—how can we quickly form an MWSN to cover a designated working area on the ground using an unmanned aerial vehicle (UAV) swarm? This problem is of significance in many military and civilian applications. In this paper, inspired by intermolecular forces, a novel molecular force field-based optimal deployment algorithm for a UAV swarm is proposed to solve this problem. A multi-rotor UAV swarm is used to carry sensors and quickly build an MWSN in a designated working area. The necessary minimum number of UAVs is determined according to the principle that the coverage area of any three UAVs has the smallest overlap. Based on the geometric properties of a convex polygon, two initialization methods are proposed to make the initial deployment more uniform, following which, the positions of all UAVs are subsequently optimized by the proposed molecular force field-based deployment algorithm. Simulation experime... [more]
Improved Q-Learning Method for Linear Discrete-Time Systems
Jian Chen, Jinhua Wang, Jie Huang
May 22, 2020 (v1)
Keywords: least squares regression, model-free control, optimal control, Q-learning, reinforcement learning, ridge regression
In this paper, the Q-learning method for quadratic optimal control problem of discrete-time linear systems is reconsidered. The theoretical results prove that the quadratic optimal controller cannot be solved directly due to the linear correlation of the data sets. The following corollaries have been made: (1) The correlation of data is the key factor in the success for the calculation of quadratic optimal control laws by Q-learning method; (2) The control laws for linear systems cannot be derived directly by the existing Q-learning method; (3) For nonlinear systems, there are some doubts about the data independence of current method. Therefore, it is necessary to discuss the probability of the controllers established by the existing Q-learning method. To solve this problem, based on the ridge regression, an improved model-free Q-learning quadratic optimal control method for discrete-time linear systems is proposed in this paper. Therefore, the computation process can be implemented co... [more]
Optimum Design of a Standalone Solar Photovoltaic System Based on Novel Integration of Iterative-PESA-II and AHP-VIKOR Methods
Hussein Mohammed Ridha, Chandima Gomes, Hashim Hizam, Masoud Ahmadipour, Dhiaa Halboot Muhsen, Saleem Ethaib
May 22, 2020 (v1)
Keywords: AHP, numerical method, optimal sizing, PESA-II, standalone PV system, storage battery
Solar energy is considered one of the most important renewable energy resources, and can be used to power a stand-alone photovoltaic (SAPV) system for supplying electricity in a remote area. However, inconstancy and unpredictable amounts of solar radiation are considered major obstacles in designing SAPV systems. Therefore, an accurate sizing method is necessary to apply in order to find an optimal configuration and fulfil the required load demand. In this study, a novel hybrid sizing approach was developed on the basis of techno-economic objectives to optimally size the SAPV system. The proposed hybrid method consisted of an intuitive method to estimate initial numbers of PV modules and storage battery, an iterative approach to accurately generate a set of wide ranges of optimal configurations, and a Pareto envelope-based selection algorithm (PESA-II) to reduce large configuration by efficacy obtaining a set of Pareto front (PF) solutions. Subsequently, the optimal configurations were... [more]
Recovering Scandium from Scandium Rough Concentrate Using Roasting-Hydrolysis-Leaching Process
Junhui Xiao, Yang Peng, Wei Ding, Tao Chen, Kai Zou, Zhen Wang
May 22, 2020 (v1)
Keywords: hydrolysis, leaching, roasting, scandium, scandium rough concentrate
In this study, a roasting-hydrolysis-acid leaching process is used to extract scandium from the scandium rough concentrate. The scandium rough concentrate containing Sc2O3 of 76.98 g/t was obtained by magnetic separation, gravity separation, and electric separation from Sc-bearing Vi-Ti magnetite tailings in the Panxi area of China. The majority of scandium in scandium rough concentrate mainly occurs in diopside, titanopyroxene, montmorillonite, chlorite, talc, aluminosilicate minerals, and isomorphism. Sodium salt and scandium coarse concentrate are added into the roasting furnace for roasting, which makes the fusion reaction of silicon, aluminum and sodium salt to produce soluble salts such as sodium silicate and sodium metaaluminate. Scandium is further recovered from the hydrolysis residue by acid leaching. Test results show scandium leaching recovery of 95.12% and the acid leaching residue with Sc2O3 content of 8.12 g/t are obtained, while the extraction of scandium is obvious. Th... [more]
A Review of Exergy Based Optimization and Control
Corey James, Tae Young Kim, Robert Jane
May 22, 2020 (v1)
Keywords: control, Energy, Exergy, Optimization
This work presents a critical review of the use of exergy based control and optimization for efficiency improvements in energy networks, with a background of exergy based analysis given for context. Over the past three decades, a number of studies using exergy were conducted to gain a performance advantage for high energy consumption systems and networks. Due to their complexity and the increased scale of the systems, the opportunity to misuse energy inevitability leads to inefficient operations. The studies accomplished in this area are grouped into either control or optimization to highlight each method’s ability to minimize system irreversibilities that lead to exergy destruction. The exergy based optimization and control studies featured demonstrate substantial improvements (as high as 40%) over traditional methods based on the first law of thermodynamics. This paper reviews the work completed in the area of exergy based optimization and control as of the end of September 2019, out... [more]
Finite Element Analysis in Setting of Fillings of V-Shaped Tooth Defects Made with Glass-Ionomer Cement and Flowable Composite
Tsanka Dikova, Tihomir Vasilev, Vesela Hristova, Vladimir Panov
May 22, 2020 (v1)
Keywords: FEA, fillings, flowable composite, glass-ionomer cement, V-shaped tooth defects
The aim of the present paper is to investigate the deformation−stress state of fillings of V-shaped tooth defects by finite element analysis (FEA). Two different materials are used—auto-cured resin-reinforced glass-ionomer cement (GIC) and flowable photo-cured composite (FPC). Two materials are placed into the cavity in one portion, as before the application of the composite the cavity walls are covered with a thin adhesive layer. Deformations and equivalent von Mises stresses are evaluated by FEA. Experimental study of micro-leakage is performed. It is established that there is an analogous non-homogeneous distribution of equivalent Von Mises stresses at fillings of V-shaped defects, made with GIC and FPC. Maximum stresses are generated along the boundaries of the filling on the vestibular surface of the tooth and at the bottom of the filling itself. Values of equivalent Von Mises stresses of GIC fillings are higher than that of FPC. Magnitude and character of deformation distribution... [more]
Steady-State Water Drainage by Oxygen in Anodic Porous Transport Layer of Electrolyzers: A 2D Pore Network Study
Haashir Altaf, Nicole Vorhauer, Evangelos Tsotsas, Tanja Vidaković-Koch
May 22, 2020 (v1)
Keywords: drainage invasion, electrolysis, pore network model, pore size distribution, porous transport layer
Recently, pore network modelling has been attracting attention in the investigation of electrolysis. This study focuses on a 2D pore network model with the purpose to study the drainage of water by oxygen in anodic porous transport layers (PTL). The oxygen gas produced at the anode catalyst layer by the oxidation of water flows counter currently to the educt through the PTL. When it invades the water-filled pores of the PTL, the liquid is drained from the porous medium. For the pore network model presented here, we assume that this process occurs in distinct steps and applies classical rules of invasion percolation with quasi-static drainage. As the invasion occurs in the capillary-dominated regime, it is dictated by the pore structure and the pore size distribution. Viscous and liquid film flows are neglected and gravity forces are disregarded. The curvature of the two-phase interface within the pores, which essentially dictates the invasion process, is computed from the Young Laplace... [more]
Ketone Solvent to Reduce the Minimum Miscibility Pressure for CO2 Flooding at the South Sumatra Basin, Indonesia
Adi Novriansyah, Wisup Bae, Changhyup Park, Asep K. Permadi, Shabrina Sri Riswati
May 22, 2020 (v1)
Subject: Other
Keywords: alcohol, CO2 flooding, ketone, minimum miscibility pressure, vanishing interfacial tension
This paper experimentally analyzes the chemical additives, i.e., methanol and ethanol, as alcohol solvents, and acetone as a ketone solvent, and the temperature influencing the minimum miscibility pressure (MMP) that is essential to design miscible CO2 flooding at an oil field, the South Sumatra basin, Indonesia. The experiments were designed to measure CO2-oil interfacial tension with the vanishing interfacial tension (VIT) method in the ranges up to 3000 psi (208.6 bar) and 300 degrees Celsius. The experiment results show that lower temperatures, larger solvent volumes, and the acetone were effective in reducing MMP. The acetone, an aprotic ketone solvent, reduced MMP more than the methanol and the ethanol in the CO2-oil system. The high temperature was negative to obtain the high CO2 solubility into the oil as well as the lower MMP. The experimental results confirm that the aprotic ketone solvent could be effective in decreasing the MMP for the design of miscible CO2 flooding at the... [more]
Evaluation of Polymeric Materials for Chemical Enhanced Oil Recovery
Alison J. Scott, Laura Romero-Zerón, Alexander Penlidis
May 22, 2020 (v1)
Subject: Materials
Keywords: enhanced oil recovery (EOR), partially hydrolyzed polyacrylamide (HPAM), polyacrylamide, polymer flooding, xanthan gum
Polymer flooding is a promising enhanced oil recovery (EOR) technique; sweeping a reservoir with a dilute polymer solution can significantly improve the overall oil recovery. In this overview, polymeric materials for enhanced oil recovery are described in general terms, with specific emphasis on desirable characteristics for the application. Application-specific properties should be considered when selecting or developing polymers for enhanced oil recovery and should be carefully evaluated. Characterization techniques should be informed by current best practices; several are described herein. Evaluation of fundamental polymer properties (including polymer composition, microstructure, and molecular weight averages); resistance to shear/thermal/chemical degradation; and salinity/hardness compatibility are discussed. Finally, evaluation techniques to establish the polymer flooding performance of candidate EOR materials are described.
Robust Mixed H2/H∞ State Feedback Controller Development for Uncertain Automobile Suspensions with Input Delay
Nan Liu, Hui Pang, Rui Yao
May 22, 2020 (v1)
Keywords: active suspension, input delay, robust control
In order to achieve better dynamics performances of a class of automobile active suspensions with the model uncertainties and input delays, this paper proposes a generalized robust linear H2/H∞ state feedback control approach. First, the mathematical model of a half-automobile active suspension is established. In this model, the H∞ norm of body acceleration is determined as the performance index of the designed controller, and the hard constraints of suspension dynamic deflection, tire dynamic load and actuator saturation are selected as the generalized H2 performance output index of the designed controller to satisfy the suspension safety requirements. Second, a generalized H2/H∞ guaranteed cost state-feedback controller is developed in terms of Lyapunov stability theory. In addition, the Cone Complementarity Linearization (CCL) algorithm is employed to convert the generalized H2/H∞ output-feedback control problem into a finite convex optimization problem (COP) in a linear matrix ineq... [more]
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