Records Added in June 2019
Records added in June 2019
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Showing records 1 to 25 of 41. [First] Page: 1 2 Last
Data Science-Enabled Molecular-to-Systems Engineering for Sustainable Water Treatment
Elvis Eugene, William Phillip, Alexander Dowling
October 11, 2019 (v3)
Keywords: Bayesian optimization, design of experiments, fit-for-purpose water, inverse materials design, materials informatics, superstructure optimization, uncertainty quantification
Growing social and economic pressures demand technological innovations that enable the widespread usage of unconventional sources of water. These challenges motivate the emerging fit-for-purpose paradigm, wherein water is provided at the precise quality level of the intended application. Unfortunately, to date, fundamental advances in materials and nanotechnology have been slow to advance this paradigm. Using examples from membrane science and engineering, we highlight the critical need to bridge research at the molecular and nano-scales with development at the device and systems-scales to fully realize sustainable fit-for-purpose water technology. Specifically, we present four opportunities for computing and data science to accelerate convergence of sustainable water research: materials informatics and inverse design, model-based design of experiments, superstructure optimization, and uncertainty quantification. As such, we highlight opportunities to collaboratively revolutionize mole... [more]
Techno-economic and environmental analyses of a novel, sustainable process for production of liquid fuels using helium heat transfer
Leila Hoseinzade, Thomas A Adams II
September 26, 2019 (v2)
Keywords: Biomass, Carbonless heat, Dimethyl Ether, Fischer-Tropsch Synthesis, Gasification, Methane Reforming, Negative emissions
In this paper, several new processes are proposed which co-generate electricity and liquid fuels (such as diesel, gasoline, or dimethyl ether) from biomass, natural gas and heat from a high temperature gas-cooled reactor. This carbonless heat provides the required energy to drive an endothermic steam methane reforming process, which yields H2-rich syngas (H2/CO > 6) with lower greenhouse gas emissions than traditional steam methane reforming processes. Since downstream Fischer-Tropsch, methanol, or dimethyl ether synthesis processes require an H2/CO ratio of around 2, biomass gasification is integrated into the process. Biomass-derived syngas is sufficiently H2-lean such that blending it with the steam methane reforming derived syngas yields a syngas of the appropriate H2/CO ratio of around 2. In a prior work, we also demonstrated that integrating carbonless heat with combined steam and CO2 reforming of methane is a promising option to produce a syngas with proper H2/CO ratio for Fisch... [more]
An Integrated Delphi-AHP and Fuzzy TOPSIS Approach toward Ranking and Selection of Renewable Energy Resources in Pakistan
Yasir Ahmed Solangi, Qingmei Tan, Nayyar Hussain Mirjat, Gordhan Das Valasai, Muhammad Waris Ali Khan, Muhammad Ikram
June 18, 2019 (v1)
Subject: Energy Policy
Keywords: analytical hierarchy process, Delphi, fuzzy technique for order of preference by similarity to ideal solution techniques, renewable energy (RE) resources, sustainable energy planning
Pakistan has long relied on fossil fuels for electricity generation. This is despite the fact that the country is blessed with enormous renewable energy (RE) resources, which can significantly diversify the fuel mix for electricity generation. In this study, various renewable resources of Pakistan—solar, hydro, biomass, wind, and geothermal energy—are analyzed by using an integrated Delphi-analytical hierarchy process (AHP) and fuzzy technique for order of preference by similarity to ideal solution (F-TOPSIS)-based methodology. In the first phase, the Delphi method was employed to define and select the most important criteria for the selection of RE resources. This process identified four main criteria, i.e., economic, environmental, technical, and socio-political aspects, which are further supplemented by 20 sub-criteria. AHP is later used to obtain the weights of each criterion and the sub-criteria of the decision model. The results of this study reveal wind energy as the most feasib... [more]
Availability Assessment of IMA System Based on Model-Based Safety Analysis Using AltaRica 3.0
Haiyong Dong, Qingfan Gu, Guoqing Wang, Zhengjun Zhai, Yanhong Lu, Miao Wang
June 18, 2019 (v1)
Subject: Other
Keywords: AltaRica 3.0, availability assessment, integrated modular avionics, model-based safety analysis
The integrated modular avionics (IMA) system is widely used in all classes of aircraft as a result of its high functional integration and resource utilization in developing advanced avionics systems. However, a series of challenges related to safety assessment exist in the background of the logical architecture for multi-message interactions of the IMA system. Traditional safety assessment methods are mainly based on engineering experience, and are difficult to reuse, incomplete, and even error-prone. Here we propose a method to assess the availability of the IMA system based on the thinking of model-based safety analysis. To aid the proposed method, we implement a tool to generate a AltaRica 3.0 file used to assess the IMA system model. The simulation results show that the proposed method makes the availability assessment fast, efficient, and effective. Moreover, we apply this method to the modification analysis of the IMA system under the condition of satisfying the safety requiremen... [more]
Development of 3D Finite Element Method for Non-Aqueous Phase Liquid Transport in Groundwater as Well as Verification
Wei Yu, Hong Li
June 18, 2019 (v1)
Keywords: finite element method, FLAC, mixed-form formulation, non-aqueous phase liquid, two-phase flow
Groundwater contamination previously occurred at a broad range of locations in present-day China. There are thousands of kinds of contaminants which can be divided into soluble and insoluble categories in groundwater. In recent years, the non-aqueous phase liquid (NAPL) pollution that belongs to the multi-phase seepage flow phenomenon has become an increasingly prominent topic due to the challenge brought by groundwater purification and its treatment. Migrating with seepage flow and moving into the potable water sources, these contaminants directly endanger people’s health. Therefore, it is necessary to research how these contaminants not only migrate, but also are then accordingly remedied. First, as an analysis means, an effective numerical method is necessary to be built. A three-dimensional finite element method program for analyzing two-phase flow in porous media, which can be applied to the immiscible contaminant transport problem in subsurface flow has been developed in this pap... [more]
Carbon Mineralization by Reaction with Steel-Making Waste: A Review
Mohamed H. Ibrahim, Muftah H. El-Naas, Abdelbaki Benamor, Saad S. Al-Sobhi, Zhien Zhang
June 18, 2019 (v1)
Keywords: Carbon Capture, CO2 sequestration, steel slag, steel-making waste
Carbon capture and sequestration (CCS) is taking the lead as a means for mitigating climate change. It is considered a crucial bridging technology, enabling carbon dioxide (CO₂) emissions from fossil fuels to be reduced while the energy transition to renewable sources is taking place. CCS includes a portfolio of technologies that can possibly capture vast amounts of CO₂ per year. Mineral carbonation is evolving as a possible candidate to sequester CO₂ from medium-sized emissions point sources. It is the only recognized form of permanent CO₂ storage with no concerns regarding CO₂ leakage. It is based on the principles of natural rock weathering, where the CO₂ dissolved in rainwater reacts with alkaline rocks to form carbonate minerals. The active alkaline elements (Ca/Mg) are the fundamental reactants for mineral carbonation reaction. Although the reaction is thermodynamically favored, it takes place over a large time scale. The challenge of mineral carbonation is to offset this limitat... [more]
Investigation of Nonthermal Plasma Assisted Charcoal Gasification for Production of Hydrogen-Rich Syngas
Yin Pang, Thomas Hammer, Dominik Müller, Jürgen Karl
June 18, 2019 (v1)
Keywords: carbon conversion, charcoal gasification, hydrogen release, nonthermal plasma, reaction kinetics, reaction mechanism
The motivation of this work is to investigate experimentally the influence of nonthermal plasma (NTP) application on the reaction kinetics of atmospheric pressure steam gasification of charcoal using a thermostatically controlled drop tube reactor. A gliding-arc generator provides about 1 kW electrical power NTP. For comparison thermal gasification is investigated under comparable flow and specific energy input conditions providing additional heat to the steam. Optical temperature measurement 20 cm flow down of the NTP zone is utilized to characterize the specific enthalpy of the reactive flow. The composition of produced syngas is measured by a gas analyzer and used for the calculation of gas flow rates. The results show a NTP-enhancement on the production of individual syngas components (H₂, CO, CH₄), especially on hydrogen production by around 39%. The syngas-based carbon conversion and hydrogen release are calculated from the carbon and hydrogen balance between the correspondent co... [more]
Comparison of the Utilization of 110 °C and 120 °C Heat Sources in a Geothermal Energy System Using Organic Rankine Cycle (ORC) with R245fa, R123, and Mixed-Ratio Fluids as Working Fluids
Mochamad Denny Surindra, Wahyu Caesarendra, Totok Prasetyo, Teuku Meurah Indra Mahlia, Taufik
June 18, 2019 (v1)
Keywords: binary cycle, Dieng, geothermal energy, Indonesia, mixture ratio, Organic Rankine Cycle (ORC), R123, R245fa
Binary cycle experiment as one of the Organic Rankine Cycle (ORC) technologies has been known to provide an improved alternate scenario to utilize waste energy with low temperatures. As such, a binary geothermal power plant simulator was developed to demonstrate the geothermal energy potential in Dieng, Indonesia. To better understand the geothermal potential, the laboratory experiment to study the ORC heat source mechanism that can be set to operate at fixed temperatures of 110 °C and 120 °C is conducted. For further performance analysis, R245fa, R123, and mixed ratio working fluids with mass flow rate varied from 0.1 kg/s to 0.2 kg/s were introduced as key parameters in the study. Data from the simulator were measured and analyzed under steady-state condition with a 20 min interval per given mass flow rate. Results indicate that the ORC system has better thermodynamic performance when operating the heat source at 120 °C than those obtained from 110 °C. Moreover, the R123 fluid produc... [more]
Enhanced Lifetime Cathode for Alkaline Electrolysis Using Standard Commercial Titanium Nitride Coatings
William J. F. Gannon, Daniel R. Jones, Charles W. Dunnill
June 18, 2019 (v1)
Subject: Materials
Keywords: alkaline electrolysis, Energy Storage, stainless steel, titanium nitride
The use of hydrogen gas as a means of decoupling supply from demand is crucial for the transition to carbon-neutral energy sources and a greener, more distributed energy landscape. This work shows how simple commercially available titanium nitride coatings can be used to extend the lifetime of 316 grade stainless-steel electrodes for use as the cathode in an alkaline electrolysis cell. The material was subjected to accelerated ageing, with the specific aim of assessing the coating’s suitability for use with intermittent renewable energy sources. Over 2000 cycles lasting 5.5 days, an electrolytic cell featuring the coating outperformed a control cell by 250 mV, and a reduction of overpotential at the cathode of 400 mV was observed. This work also confirms that the coating is solely suitable for cathodic use and presents an analysis of the surface changes that occur if it is used anodically.
Parallel Conical Area Community Detection Using Evolutionary Multi-Objective Optimization
Weiqin Ying, Hassan Jalil, Bingshen Wu, Yu Wu, Zhenyu Ying, Yucheng Luo, ZhenYu Wang
June 18, 2019 (v1)
Subject: Optimization
Keywords: community detection, complex networks, evolutionary algorithms, multi-objective optimization, parallel island models
Detecting community structures helps to reveal the functional units of complex networks. In this paper, the community detection problem is regarded as a modularity-based multi-objective optimization problem (MOP), and a parallel conical area community detection algorithm (PCACD) is designed to solve this MOP effectively and efficiently. In consideration of the global properties of the selection and update mechanisms, PCACD employs a global island model and targeted elitist migration policy in a conical area evolutionary algorithm (CAEA) to discover community structures at different resolutions in parallel. Although each island is assigned only a portion of all sub-problems in the island model, it preserves a complete population to accomplish the global selection and update. Meanwhile the migration policy directly migrates each elitist individual to an appropriate island in charge of the sub-problem associated with this individual to share essential evolutionary achievements. In additio... [more]
Numerical Simulation of the Effects of the Helical Angle on the Decaying Swirl Flow of the Hole Cleaning Device
Jingyu Qu, Tie Yan, Xiaofeng Sun, Zijian Li, Wei Li
June 18, 2019 (v1)
Keywords: Computational Fluid Dynamics, decaying swirl flow, hole cleaning device, horizontal wellbore, swirl intensity
The application of the hole cleaning device in downhole is a new technology that can improve the problem of cuttings accumulation in the annulus and improve the hole cleaning effect of the wellbore during drilling. In this paper, the Reynolds Averaged Navier⁻Stokes model, together with the Realizable k-ε turbulence model, are used to perform transient simulations. The effects of rotational speed, blade shape, and helical angle on the initial swirl intensity and its decay behavior along the flow direction are studied. The swirl number, the initial swirl intensity, the decay rate, the tangential velocity distribution, and the variation of pressure are analyzed. The results indicate that the swirl number of the swirl flow exponentially decays along the flow direction. The straight blade and V-shaped blade have different swirl flow induction mechanisms. Under specific drilling parameters, the critical helical angle is determined for both types of blades. When the selection of the helical a... [more]
Degradation of Aqueous Polycyclic Musk Tonalide by Ultraviolet-Activated Free Chlorine
Lili Wang, Xiaowei Liu
June 10, 2019 (v1)
Subject: Other
Keywords: degradation mechanism, polycyclic musks, UV/chlorine advanced oxidation process, water treatment
Chlorine-incorporating ultraviolet (UV) provides a multiple barrier for drinking water disinfection. Meanwhile, post-UV employment can promote the degradation of micropollutants by radical production from chlorine residual photolysis. This work studied the degradation of one such chemical, tonalide (AHTN), by low-pressure UV-activated free chlorine (FC) under typical UV disinfection dosage of HCO 3 − > Cu 2 + > PO 4 3 − > Fe 2 + . Reaction product analysis showed ignorable formation of chlorinated intermediates and disinfection byproducts.
Flocculation of a High-Turbidity Kaolin Suspension Using Hydrophobic Modified Quaternary Ammonium Salt Polyacrylamide
Jiangya Ma, Xue Fu, Wei Xia, Kun Fu, Yi Liao
June 10, 2019 (v1)
Keywords: high turbidity, hydrophobic, kaolin, polyacrylamide, quaternary ammonium salt
In this work, a novel cationic polyacrylamide (PAMD) was synthesized by acrylamide (AM) diallyl dimethyl ammonium chloride (DMD) and dodecyl polyglucoside (DPL) under low-pressure ultraviolet (UV) initiation. The intrinsic viscosity and cationic degree of PAMD were optimized in copolymerization. The optimum synthesis conditions that affect polymerization were determined to be solid content 30%, DPL content 25%, DMD content 30%, illumination time 135 min, and pH 9. The flocculation performance of flocculant PAMD with a high cationic degree was investigated in the purification of high-turbidity water. The flocculation mechanism was correspondingly studied and summarized based on Fourier transform-infrared (FTIR) analysis. Finally, the results of an experimental simulation using the response surface method show that 98.9% supernatant transmittance was achieved under dosage 4 mg/L, fast stirring time 20 min, pH 7, and stirring speed 320 rpm.
Extraction of Oil and Minor Compounds from Oil Palm Fruit with Supercritical Carbon Dioxide
Huan Phan Tai, Gerd Brunner
June 10, 2019 (v1)
Keywords: carotenoids, Modelling, supercritical extraction, tocopherols, tocotrienols
A significant quantity of tocochromanols and carotenoids remains in the residual from palm oil production by traditional screw pressing. Supercritical carbon dioxide extraction was used as alternative method with the purpose to recover better these valuable minor compounds. Total oil yield and co-extracted water were investigated in the course of extraction. Tocochromanols and carotenoids were evaluated, not only in the extraction oil, but also in the oil of residual fibre. Modelling of extraction process was also performed for a further up-scaling. The results showed that oil yield up to 90% could be observed within 120 min. Supercritical carbon dioxide (SCCO₂) could extract tocochromanols and carotenoids with concentration in the same range of normal commercial processing palm oil, while co-extracted water remained rather low at a level of 2⁻4%. Moreover, recovery efficiencies of these minor compounds were much higher in case of extraction processed with supercritical carbon dioxide... [more]
Long-Term Stability of Thin-Film Pd-Based Supported Membranes
Niek de Nooijer, Alba Arratibel Plazaola, Jon Meléndez Rey, Ekain Fernandez, David Alfredo Pacheco Tanaka, Martin van Sint Annaland, Fausto Gallucci
June 10, 2019 (v1)
Subject: Materials
Keywords: fluidized bed, hydrogen production, membrane reactors, membrane stability, Palladium based membranes
Membrane reactors have demonstrated a large potential for the production of hydrogen via reforming of different feedstocks in comparison with other reactor types. However, the long-term performance and stability of the applied membranes are extremely important for the possible industrial exploitation of these reactors. This study investigates the long-term stability of thin-film Pd-Ag membranes supported on porous Al₂O₃ supports. The stability of five similarly prepared membranes have been investigated for 2650 h, up to 600 °C and in fluidized bed conditions. Results show the importance and the contribution of the sealing of the membranes at temperatures up to 500 °C. At higher temperatures the membranes surface deformation results in pinhole formation and a consequent decrease in selectivity. Stable operation of the membranes in a fluidized bed is observed up to 450 °C, however, at higher temperatures the scouring action of the particles under fluidization causes significant deformati... [more]
Biomaterial Implants in Abdominal Wall Hernia Repair: A Review on the Importance of the Peritoneal Interface
Verónica Gómez-Gil, Gemma Pascual, Juan M. Bellón
June 10, 2019 (v1)
Subject: Biosystems
Keywords: abdominal wall, hernia recurrence, hernia repair, omentum, peritoneal adhesions, peritoneum, polypropylene, surgical mesh
Biomaterials have long been used to repair defects in the clinical setting, which has led to the development of a wide variety of new materials tailored to specific therapeutic purposes. The efficiency in the repair of the defect and the safety of the different materials employed are determined not only by the nature and structure of their components, but also by the anatomical site where they will be located. Biomaterial implantation into the abdominal cavity in the form of a surgical mesh, such as in the case of abdominal hernia repair, involves the contact between the foreign material and the peritoneum. This review summarizes the different biomaterials currently available in hernia mesh repair and provides insights into a series of peculiarities that must be addressed when designing the optimal mesh to be used in this interface.
Profile Monitoring for Autocorrelated Reflow Processes with Small Samples
Shu-Kai S. Fan, Chih-Hung Jen, Jai-Xhing Lee
June 10, 2019 (v1)
Keywords: EWMA control chart, Hotelling’s T2 control chart, polynomial regression model, profile monitoring, sum of sine function
The methodology of profile monitoring combines both the model fitting and statistical process control (SPC) techniques. Over the past ten years, a variety of profile monitoring methods have been proposed and extensively investigated in terms of different process profiles. However, monitoring tasks still exhibit a primary problem in that the errors surrounding the functional relationship are frequently assumed to be independent within every single profile. However, the assumption of independence is an unrealistic assumption in many practical instances. In particular, within-profile autocorrelation often occurs in the profile data. To mitigate the within-profile autocorrelation, a monitoring method incorporating an autoregressive (AR)(1) model to cope with autocorrelation is proposed. In this paper, the reflow process with small samples in surface mount technology (SMT) is investigated. In Phase I, three different process models are compared in combination with the first-order autoregres... [more]
Scheduling of Energy-Integrated Batch Process Systems Using a Pattern-Based Framework
Sujit Suresh Jogwar, Shrikant Mete, Channamallikarjun S. Mathpati
June 10, 2019 (v1)
Keywords: batch scheduling, energy integration, mixed-integer optimization, patterns
In this paper, a novel pattern-based method is developed for the generation of optimal schedules for energy-integrated batch process systems. The proposed methodology is based on the analysis of available schedules for the identification of repetitive patterns. It is shown that optimal schedules of energy-integrated batch processes are composed of several repeating sections (or building blocks), and their sizes and relative positions are dependent on the scheduling horizon and constraints. Based on such a decomposition, the proposed pattern-based algorithm generates an optimal schedule by computing the number and sequence of these blocks. The framework is then integrated with rigorous optimization-based approach wherein it is shown that the learning from the pattern-based solution significantly improves the performance of rigorous optimization. The main advantage of the pattern-based method is the significant reduction in computational time required to solve large scheduling problems,... [more]
Dynamics of Water Quality: Impact Assessment Process for Water Resource Management
Ejaz-ul-Hassan Bhatti, Mudasser Muneer Khan, Syyed Adnan Raheel Shah, Syed Safdar Raza, Muhammad Shoaib, Muhammad Adnan
June 10, 2019 (v1)
Subject: Other
Keywords: sodium absorption, water management, water quality, wilcox diagram
Surface water is an important source of water supply for irrigation purpose and in urban areas, sewage water is being disposed of in nearby canals without treatment. A study was conducted to investigate the dynamics of water quality of irrigation canal as a result of this practice. The study ascertained the impact of different salinity parameters, indices and approaches to examine the hazardous effects on quality of canal water. The study analyses the samples collected for various parameters like pH, TDS, EC, Na, Cl, Ca, Mg, K, CO₃, HCO₃ etc. It helped to decide the restriction on use of water based on FAO-UN guidelines. Investigations were focused on assessment of contaminants affecting the quality of water and having hazardous effects on different stages of irrigation water usage. Wilcox diagram and Doneen’s approach-based analysis helped to identify the class and quality of water. This study shall help to analyze the quality of water and provide support to the decision makers for be... [more]
Discrete Element Method Model Optimization of Cylindrical Pellet Size
Jiri Rozbroj, Jiri Zegzulka, Jan Necas, Lucie Jezerska
June 10, 2019 (v1)
Keywords: DEM, friction coefficient, hopper discharge, particle image velocimetry, pellets
The DEM (Discrete Element Method) is one option for studying the kinematic behaviour of cylindrical pellets. The DEM experiments attempted to optimize the numerical model parameters that affected time and velocity as a cylindrical vessel emptied. This vessel was filled with cylindrical pellets. Optimization was accomplished by changing the coefficient of friction between particles and selecting the length accuracy grade of the sample cylindrical pellets. The initial state was a series of ten vessel-discharge experiments evaluated using PIV (Particle Image Velocimetry). The cylindrical pellet test samples were described according to their length in three accuracy grades. These cylindrical pellet length accuracy grades were subsequently used in the DEM simulations. The article discusses a comparison of the influence of the length accuracy grade of cylindrical pellets on optimal calibration of time and velocity when the cylindrical vessel is emptied. The accuracy grade of cylindrical pell... [more]
Hybrid Approach for Optimisation and Analysis of Palm Oil Mill
Steve Z. Y. Foong, Viknesh Andiappan, Raymond R. Tan, Dominic C. Y. Foo, Denny K. S. Ng
June 10, 2019 (v1)
Subject: Optimization
Keywords: feasible operating range analysis, flexibility index, graphical approach, mathematical programming, utilisation index
A palm oil mill produces crude palm oil, crude palm kernel oil and other biomass from fresh fruit bunches. Although the milling process is well established in the industry, insufficient research and development reported in optimising and analysing the operations of a palm oil mill. The performance of a palm oil mill (e.g., costs, utilisation and flexibility) is affected by factors such as operating time, capacity and fruit availability. This paper presents a hybrid combined mathematical programming and graphical approach to solve and analyse a palm oil mill case study in Malaysia. The hybrid approach consists of two main steps: (1) optimising a palm oil milling process to achieve maximum economic performance via input-output optimisation model (IOM); and (2) performing a feasible operating range analysis (FORA) to study the utilisation and flexibility of the developed design. Based on the optimised results, the total equipment units needed is reduced from 39 to 26 unit, bringing down t... [more]
The Application of a Three-Dimensional Deterministic Model in the Study of Debris Flow Prediction Based on the Rainfall-Unstable Soil Coupling Mechanism
Shuangshuang Qiao, Shengwu Qin, Junjun Chen, Xiuyu Hu, Zhongjun Ma
June 10, 2019 (v1)
Keywords: debris flow, forecasting, Jiaohe, rainfall-unstable soil coupling mechanism(R-USCM), scoops3D
As debris flow is one of the most destructive natural disasters in many parts of the world, the assessment and management of future debris flows with proper forecasting methods are crucial for the safety of life and property. So increasing attention has been paid to the forecasting methods on debris flows. A debris flow forecasting method based on the rainfall-unstable soil coupling mechanism (R-USCM) is presented in the current study. This method is based on the debris flow formation mechanism. The density of sediment is introduced as an evaluation index to determine the susceptibility of debris flow occurrence. The forecasting method includes two phases: (1) rainfall and soil coupling and (2) runoff and unstable soil coupling. Scoops3D, a three-dimensional (3D) model for analyzing slope stability, was introduced into the debris flow forecasting method. In order to test the forecasting accuracy of this method, Jiaohe County was selected as a research area, and the serious debris flow... [more]
Improvement of Temperature Control Performance of Thermoelectric Dehumidifier Used Industry 4.0 by the SF-PI Controller
Jae-Sub Ko, Jun-Ho Huh, Jong-Chan Kim
June 10, 2019 (v1)
Keywords: computer architecture, dehumidifier, fuzzy, Industry 4.0, PI controller, smart gird, temperature-control, thermoelectric element, water grid
This paper proposes the series connected fuzzy-proportional integral (SF-PI) controller, which is composed of the fuzzy control and the PI controller to improve temperature control performance of dehumidifier using a thermoelectric element. The control of conventional PI controller usually uses fixed gain. For that reason, it is limited in achieving satisfactory control performance in both transient-state and steady-state. The fuzzy control within SF-PI controller adjusts the input value of PI controller according to operating condition. The PI controller within the SF-PI controller controls the temperature of the thermoelectric element using that value. The SF-PI controller can achieve more accurate temperature control than a conventional PI controller for that reason. The SF-PI controller has been tested for various indoor environmental conditions such as temperature and relative humidity conditions. The average temperature error of the SF-PI controller between the reference temperat... [more]
Metabolic Modeling of Clostridium difficile Associated Dysbiosis of the Gut Microbiota
Poonam Phalak, Michael A. Henson
June 10, 2019 (v1)
Keywords: bacterial biofilms, Clostridium difficile infection, gut microbiota dysbiosis, metabolic modeling
Recent in vitro experiments have demonstrated the ability of the pathogen Clostridium difficile and commensal gut bacteria to form biofilms on surfaces, and biofilm development in vivo is likely. Various studies have reported that 3%⁻15% of healthy adults are asymptomatically colonized with C. difficile, with commensal species providing resistance against C. difficile pathogenic colonization. C. difficile infection (CDI) is observed at a higher rate in immunocompromised patients previously treated with broad spectrum antibiotics that disrupt the commensal microbiota and reduce competition for available nutrients, resulting in imbalance among commensal species and dysbiosis conducive to C. difficile propagation. To investigate the metabolic interactions of C. difficile with commensal species from the three dominant phyla in the human gut, we developed a multispecies biofilm model by combining genome-scale metabolic reconstructions of C. difficile, Bacteroides thetaiotaomicron from the p... [more]
An Optimization-Based Framework to Define the Probabilistic Design Space of Pharmaceutical Processes with Model Uncertainty
Daniel Laky, Shu Xu, Jose S. Rodriguez, Shankar Vaidyaraman, Salvador García Muñoz, Carl Laird
June 10, 2019 (v1)
Subject: Optimization
Keywords: flexibility analysis, global optimization, pharmaceutical processes, probabilistic design space
To increase manufacturing flexibility and system understanding in pharmaceutical development, the FDA launched the quality by design (QbD) initiative. Within QbD, the design space is the multidimensional region (of the input variables and process parameters) where product quality is assured. Given the high cost of extensive experimentation, there is a need for computational methods to estimate the probabilistic design space that considers interactions between critical process parameters and critical quality attributes, as well as model uncertainty. In this paper we propose two algorithms that extend the flexibility test and flexibility index formulations to replace simulation-based analysis and identify the probabilistic design space more efficiently. The effectiveness and computational efficiency of these approaches is shown on a small example and an industrial case study.
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