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Processes, Volume 7, Issue 2 (February 2019)

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Cover Story (view full-size image) The anaerobic bacterium Clostridium difficile is an opportunistic pathogen responsible for chronic [...] Read more.
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Open AccessArticle An Integrated Delphi-AHP and Fuzzy TOPSIS Approach toward Ranking and Selection of Renewable Energy Resources in Pakistan
Processes 2019, 7(2), 118; https://doi.org/10.3390/pr7020118
Received: 31 December 2018 / Revised: 14 February 2019 / Accepted: 15 February 2019 / Published: 25 February 2019
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Abstract
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 [...] Read more.
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 feasible RE resource for electricity generation followed by hydropower, solar, biomass, and geothermal energy. The sensitivity analysis of the decision model results shows that the results of this study are significant, reliable, and robust. The study provides important insights related to the prioritizing of RE resources for electricity generation and can be used to undertake policy decisions toward sustainable energy planning in Pakistan. Full article
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Open AccessArticle Availability Assessment of IMA System Based on Model-Based Safety Analysis Using AltaRica 3.0
Processes 2019, 7(2), 117; https://doi.org/10.3390/pr7020117
Received: 18 January 2019 / Revised: 17 February 2019 / Accepted: 20 February 2019 / Published: 25 February 2019
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Abstract
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 [...] Read more.
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 requirement. Our study can enhance the safety assessment of safety-critical systems effectively, assist the design of IMA systems, and reduce the amount of errors during the programming process of the safety model. Full article
(This article belongs to the Special Issue Optimization for Control, Observation and Safety)
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Open AccessArticle Development of 3D Finite Element Method for Non-Aqueous Phase Liquid Transport in Groundwater as Well as Verification
Processes 2019, 7(2), 116; https://doi.org/10.3390/pr7020116
Received: 30 December 2018 / Revised: 16 February 2019 / Accepted: 18 February 2019 / Published: 25 February 2019
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Abstract
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 [...] Read more.
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 paper. The fundamental theory and numerical discretization formulations are elaborated. The numerical difficulty brought about by the distinct non-linearity of the temporal evolution of saturation-dependent variables is overcome by the mixed-form formulation. The effectiveness of simultaneous solution (SS) method and its improvement in efficiency are explained. Finally, two computational examples are given for verifying the correctness and demonstrating the preliminary applicability. In addition, the function of two-phase immiscible flow, especially in Fast Lagrangian Analysis of Continua (FLAC) is used to simulate the same examples and the results are compared to further verify the correctness of the numerical development. Full article
(This article belongs to the Special Issue Fluid Flow in Fractured Porous Media)
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Open AccessFeature PaperReview Carbon Mineralization by Reaction with Steel-Making Waste: A Review
Processes 2019, 7(2), 115; https://doi.org/10.3390/pr7020115
Received: 9 February 2019 / Revised: 19 February 2019 / Accepted: 20 February 2019 / Published: 24 February 2019
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Abstract
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 [...] Read more.
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 limitation by accelerating the carbonation reaction with minimal energy and feedstock consumption. Calcium and magnesium silicates are generally selected for carbonation due to their abundance in nature. Industrial waste residues emerge as an alternative source of carbonation minerals that have higher reactivity than natural minerals; they are also inexpensive and readily available in proximity to CO2 emitters. In addition, the environmental stability of the industrial waste is often enhanced as they undergo carbonation. Recently, direct mineral carbonation has been investigated significantly due to its applicability to CO2 capture and storage. This review outlines the main research work carried out over the last few years on direct mineral carbonation process utilizing steel-making waste, with emphasis on recent research achievements and potentials for future research. Full article
(This article belongs to the Special Issue Gas Capture Processes)
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Open AccessArticle Investigation of Nonthermal Plasma Assisted Charcoal Gasification for Production of Hydrogen-Rich Syngas
Processes 2019, 7(2), 114; https://doi.org/10.3390/pr7020114
Received: 30 January 2019 / Revised: 14 February 2019 / Accepted: 19 February 2019 / Published: 21 February 2019
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Abstract
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 [...] Read more.
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 content in syngas and in the feedstock. The NTP promoted the carbon conversion and hydrogen release by 25% and 31%, respectively. The first-order reaction kinetics are determined by data-fitting in an Arrhenius diagram. The plasma enhanced the reaction rate coefficients by 27%. Based on experimental results and other literature, possible plasma-induced reactions are proposed. Full article
(This article belongs to the Special Issue Plasma-Based Processes for Improved Energy Efficiency)
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Open AccessArticle 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
Processes 2019, 7(2), 113; https://doi.org/10.3390/pr7020113
Received: 12 January 2019 / Revised: 2 February 2019 / Accepted: 15 February 2019 / Published: 21 February 2019
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Abstract
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 [...] Read more.
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 produces the highest ORC efficiency with values between 9.4% and 13.5%. Full article
(This article belongs to the Special Issue Modeling and Simulation of Energy Systems)
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Open AccessArticle Enhanced Lifetime Cathode for Alkaline Electrolysis Using Standard Commercial Titanium Nitride Coatings
Processes 2019, 7(2), 112; https://doi.org/10.3390/pr7020112
Received: 10 January 2019 / Revised: 14 February 2019 / Accepted: 18 February 2019 / Published: 21 February 2019
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Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Hydrogen Production Technologies)
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Open AccessArticle Parallel Conical Area Community Detection Using Evolutionary Multi-Objective Optimization
Processes 2019, 7(2), 111; https://doi.org/10.3390/pr7020111
Received: 21 December 2018 / Revised: 10 February 2019 / Accepted: 16 February 2019 / Published: 20 February 2019
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Abstract
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 [...] Read more.
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 addition, a modularity-based greedy local search strategy is also applied to accelerate the convergence rate. Comparative experimental results on six real-world networks reveal that PCACD is capable of discovering potential high-quality community structures at diverse resolutions with satisfactory running efficiencies. Full article
(This article belongs to the Special Issue Process Systems Engineering à la Canada)
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Open AccessArticle A Composite Evaluation Model of Sustainable Manufacturing in Machining Process for Typical Machine Tools
Processes 2019, 7(2), 110; https://doi.org/10.3390/pr7020110
Received: 30 December 2018 / Revised: 15 February 2019 / Accepted: 15 February 2019 / Published: 20 February 2019
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Abstract
Machine tool is the basic manufacturing equipment in today’s mechanical manufacturing industry. A considerable amount of energy and carbon emission are consumed in machining processes, the realization of sustainable manufacturing of machine tools have become an urgent problem to be solved in the [...] Read more.
Machine tool is the basic manufacturing equipment in today’s mechanical manufacturing industry. A considerable amount of energy and carbon emission are consumed in machining processes, the realization of sustainable manufacturing of machine tools have become an urgent problem to be solved in the field of industry and academia. Therefore, five types of machine tools were selected for the typical machining processes (turning, milling, planning, grinding and drilling). Then the model of the energy efficiency, carbon efficiency and green degree model were established in this paper which considers the theory and experiment with the resource, energy and emission modeling method. The head frame spindle and head frame box were selected to verify the feasibility and practicability of the proposed model, based on the orthogonal experiment case of the key machining process. In addition, the influence rules of machining parameters were explored and the energy efficiency and green degree of the machine tools were compared. Finally, the corresponding strategies for energy conservation and emission reduction were proposed. Full article
(This article belongs to the Special Issue Energy, Economic and Environment for Industrial Production Processes)
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Open AccessArticle Numerical Simulation of the Effects of the Helical Angle on the Decaying Swirl Flow of the Hole Cleaning Device
Processes 2019, 7(2), 109; https://doi.org/10.3390/pr7020109
Received: 16 January 2019 / Revised: 3 February 2019 / Accepted: 15 February 2019 / Published: 19 February 2019
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Abstract
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, [...] Read more.
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 angle is close to the critical value, the swirl flow will be close to the axial flow, which is of little help in hole cleaning. Moreover, the rotation direction of swirl flow will change when the helical angle exceeds the critical value. Full article
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Open AccessArticle Flocculation of a High-Turbidity Kaolin Suspension Using Hydrophobic Modified Quaternary Ammonium Salt Polyacrylamide
Processes 2019, 7(2), 108; https://doi.org/10.3390/pr7020108
Received: 25 January 2019 / Revised: 11 February 2019 / Accepted: 12 February 2019 / Published: 18 February 2019
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Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Wastewater Treatment Processes)
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Open AccessArticle Extraction of Oil and Minor Compounds from Oil Palm Fruit with Supercritical Carbon Dioxide
Processes 2019, 7(2), 107; https://doi.org/10.3390/pr7020107
Received: 19 January 2019 / Revised: 2 February 2019 / Accepted: 13 February 2019 / Published: 18 February 2019
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Abstract
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 [...] Read more.
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 than those with screw pressing method. Full article
(This article belongs to the Special Issue Advances in Supercritical Fluid Extraction)
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Open AccessFeature PaperArticle Long-Term Stability of Thin-Film Pd-Based Supported Membranes
Processes 2019, 7(2), 106; https://doi.org/10.3390/pr7020106
Received: 16 January 2019 / Revised: 1 February 2019 / Accepted: 13 February 2019 / Published: 16 February 2019
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Abstract
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 [...] Read more.
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 deformation of the palladium surface resulting in a decreased selectivity. Full article
(This article belongs to the Special Issue Catalysis in Membrane Reactors)
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Open AccessReview Biomaterial Implants in Abdominal Wall Hernia Repair: A Review on the Importance of the Peritoneal Interface
Processes 2019, 7(2), 105; https://doi.org/10.3390/pr7020105
Received: 1 January 2019 / Revised: 8 February 2019 / Accepted: 10 February 2019 / Published: 16 February 2019
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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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Biomaterials and Tissue Engineering)
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Open AccessArticle The Application of a Three-Dimensional Deterministic Model in the Study of Debris Flow Prediction Based on the Rainfall-Unstable Soil Coupling Mechanism
Processes 2019, 7(2), 99; https://doi.org/10.3390/pr7020099
Received: 15 December 2018 / Revised: 7 February 2019 / Accepted: 7 February 2019 / Published: 15 February 2019
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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 [...] Read more.
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 disasters attributed to strong rainfall on 20 July 2017 were taken as the research case. By comparing the forecasting results with the debris flow distribution map for Jiaohe County, the method based on the R-USCM is feasible for forecasting debris flows at the regional scale. The application of the Scoops3D model can more reasonably analyze the slope stability than the traditional two dimensional (2D) method and improve the forecasting ability of debris flows. Full article
(This article belongs to the Special Issue Fluid Flow in Fractured Porous Media)
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Open AccessArticle Improvement of Temperature Control Performance of Thermoelectric Dehumidifier Used Industry 4.0 by the SF-PI Controller
Processes 2019, 7(2), 98; https://doi.org/10.3390/pr7020098
Received: 22 January 2019 / Revised: 8 February 2019 / Accepted: 11 February 2019 / Published: 15 February 2019
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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 [...] Read more.
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 temperature and the thermoelectric element temperature is 22% of traditional PI’s value and consumption power is reduced by about 10%. Therefore, the SF-PI controller proposed in this paper can improved the performance of temperature control of dehumidifier using thermoelectric element. The power consumed by buildings accounts for a significant portion of the total power consumption, of which the air conditioner represents the largest energy consumer. In this paper, it is possible to reduce the energy consumption by improving the performance of the dehumidifier, one of the air conditioners, and it can be applied to various control fields in the future. Full article
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Open AccessFeature PaperArticle Metabolic Modeling of Clostridium difficile Associated Dysbiosis of the Gut Microbiota
Processes 2019, 7(2), 97; https://doi.org/10.3390/pr7020097
Received: 16 December 2018 / Revised: 30 January 2019 / Accepted: 6 February 2019 / Published: 15 February 2019
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Abstract
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. [...] Read more.
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 phylum Bacteroidetes, Faecalibacterium prausnitzii from the phylum Firmicutes, and Escherichia coli from the phylum Proteobacteria. The biofilm model was used to identify gut nutrient conditions that resulted in C. difficile-associated dysbiosis characterized by large increases in C. difficile and E. coli abundances and large decreases in F. prausnitzii abundance. We tuned the model to produce species abundances and short-chain fatty acid levels consistent with available data for healthy individuals. The model predicted that experimentally-observed host-microbiota perturbations resulting in decreased carbohydrate/increased amino acid levels and/or increased primary bile acid levels would induce large increases in C. difficile abundance and decreases in F. prausnitzii abundance. By adding the experimentally-observed perturbation of increased host nitrate secretion, the model also was able to predict increased E. coli abundance associated with C. difficile dysbiosis. In addition to rationalizing known connections between nutrient levels and disease progression, the model generated hypotheses for future testing and has the capability to support the development of new treatment strategies for C. difficile gut infections. Full article
(This article belongs to the Special Issue Methods in Computational Biology)
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Open AccessArticle Profile Monitoring for Autocorrelated Reflow Processes with Small Samples
Processes 2019, 7(2), 104; https://doi.org/10.3390/pr7020104
Received: 12 January 2019 / Revised: 2 February 2019 / Accepted: 12 February 2019 / Published: 15 February 2019
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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 [...] Read more.
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 autoregressive model, while an appropriate profile model is sought. The Hotelling T2 and exponentially weighted moving average (EWMA) control charts are used together to monitor the parameter estimates (i.e., profile shape) and residuals (i.e., profile variability), respectively. Full article
(This article belongs to the Special Issue Optimization for Control, Observation and Safety)
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Open AccessFeature PaperArticle Scheduling of Energy-Integrated Batch Process Systems Using a Pattern-Based Framework
Processes 2019, 7(2), 103; https://doi.org/10.3390/pr7020103
Received: 18 January 2019 / Revised: 6 February 2019 / Accepted: 8 February 2019 / Published: 15 February 2019
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Abstract
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 [...] Read more.
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, thus enabling the possibility of on-line rescheduling. Three literature examples were considered to demonstrate the presence of repeating patterns in optimal schedules of energy-integrated batch systems. The effectiveness of the proposed methodology was illustrated using an integrated reactor-separator system. Full article
(This article belongs to the Special Issue Design and Control of Sustainable Systems)
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Open AccessArticle Dynamics of Water Quality: Impact Assessment Process for Water Resource Management
Processes 2019, 7(2), 102; https://doi.org/10.3390/pr7020102
Received: 31 December 2018 / Revised: 24 January 2019 / Accepted: 27 January 2019 / Published: 15 February 2019
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Abstract
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 [...] Read more.
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 better water resource management and policy development for irrigation purpose i.e., treatment and distribution of water resource. Full article
(This article belongs to the Special Issue Water Quality Modelling)
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Open AccessArticle Discrete Element Method Model Optimization of Cylindrical Pellet Size
Processes 2019, 7(2), 101; https://doi.org/10.3390/pr7020101
Received: 11 January 2019 / Revised: 6 February 2019 / Accepted: 13 February 2019 / Published: 15 February 2019
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Abstract
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. [...] Read more.
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 pellet length in the DEM sample plays a significant role in relation to the complexity of a created simulation. Full article
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Open AccessFeature PaperArticle Hybrid Approach for Optimisation and Analysis of Palm Oil Mill
Processes 2019, 7(2), 100; https://doi.org/10.3390/pr7020100
Received: 11 January 2019 / Revised: 9 February 2019 / Accepted: 11 February 2019 / Published: 15 February 2019
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Abstract
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 [...] Read more.
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 the total capital investment by US$6.86 million (from 18.42 to 11.56 million US$) with 23% increment in economic performance (US$0.82 million/y) achieved. An analysis is presented to show the changes in utilisation and flexibility of the mill against capital investment. During the peak crop season, the utilisation index increases from 0.6 to 0.95 while the flexibility index decreases from 0.4 to 0.05. Full article
(This article belongs to the Special Issue Process Design, Integration, and Intensification)
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Open AccessArticle An Optimization-Based Framework to Define the Probabilistic Design Space of Pharmaceutical Processes with Model Uncertainty
Processes 2019, 7(2), 96; https://doi.org/10.3390/pr7020096
Received: 29 December 2018 / Revised: 30 January 2019 / Accepted: 1 February 2019 / Published: 14 February 2019
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Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Model-Based Tools for Pharmaceutical Manufacturing Processes)
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Open AccessArticle Degradation of Aqueous Polycyclic Musk Tonalide by Ultraviolet-Activated Free Chlorine
Processes 2019, 7(2), 95; https://doi.org/10.3390/pr7020095
Received: 6 December 2018 / Revised: 31 January 2019 / Accepted: 7 February 2019 / Published: 14 February 2019
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Abstract
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 [...] Read more.
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 <200 mJ·cm−2 and water matrix of filtered tank effluent. AHTN was rapidly degraded by UV/FC in accordance with pseudo-first-order kinetics. The reaction rate constants of AHTN with reactive chlorine species and hydroxyl radical (HO•) were estimated. Mechanistic exploration evidenced that under UV/FC, AHTN degradation was attributable to direct photolysis, ClO•, and HO•. The carbonyl side chain of AHTN served as an important attack site for radicals. Water matrices, such as natural organic matter (NOM), HCO 3 , Cu 2 + , PO 4 3 , and Fe 2 + , showed noticeable influence on the UV/FC process with an order of NOM > HCO 3 > Cu 2 + > PO 4 3 > Fe 2 + . Reaction product analysis showed ignorable formation of chlorinated intermediates and disinfection byproducts. Full article
(This article belongs to the Special Issue Application of Advanced Oxidation Processes)
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Open AccessFeature PaperReview Accelerating Biologics Manufacturing by Modeling or: Is Approval under the QbD and PAT Approaches Demanded by Authorities Acceptable without a Digital-Twin?
Processes 2019, 7(2), 94; https://doi.org/10.3390/pr7020094
Received: 16 November 2018 / Revised: 16 January 2019 / Accepted: 31 January 2019 / Published: 13 February 2019
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Abstract
Innovative biologics, including cell therapeutics, virus-like particles, exosomes, recombinant proteins, and peptides, seem likely to substitute monoclonal antibodies as the main therapeutic entities in manufacturing over the next decades. This molecular variety causes a growing need for a general change of methods as [...] Read more.
Innovative biologics, including cell therapeutics, virus-like particles, exosomes, recombinant proteins, and peptides, seem likely to substitute monoclonal antibodies as the main therapeutic entities in manufacturing over the next decades. This molecular variety causes a growing need for a general change of methods as well as mindset in the process development stage, as there are no platform processes available such as those for monoclonal antibodies. Moreover, market competitiveness demands hyper-intensified processes, including accelerated decisions toward batch or continuous operation of dedicated modular plant concepts. This indicates gaps in process comprehension, when operation windows need to be run at the edges of optimization. In this editorial, the authors review and assess potential methods and begin discussing possible solutions throughout the workflow, from process development through piloting to manufacturing operation from their point of view and experience. Especially, the state-of-the-art for modeling in red biotechnology is assessed, clarifying differences and applications of statistical, rigorous physical-chemical based models as well as cost modeling. “Digital-twins” are described and efforts vs. benefits for new applications exemplified, including the regulation-demanded QbD (quality by design) and PAT (process analytical technology) approaches towards digitalization or industry 4.0 based on advanced process control strategies. Finally, an analysis of the obstacles and possible solutions for any successful and efficient industrialization of innovative methods from process development, through piloting to manufacturing, results in some recommendations. A central question therefore requires attention: Considering that QbD and PAT have been required by authorities since 2004, can any biologic manufacturing process be approved by the regulatory agencies without being modeled by a “digital-twin” as part of the filing documentation? Full article
(This article belongs to the Special Issue Processes Accelerating Biologics Manufacturing by Modelling)
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Open AccessArticle Cogeneration Process Technical Viability for an Apartment Building: Case Study in Mexico
Processes 2019, 7(2), 93; https://doi.org/10.3390/pr7020093
Received: 29 December 2018 / Revised: 5 February 2019 / Accepted: 7 February 2019 / Published: 13 February 2019
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Abstract
The objective of this paper is to evaluate and to simulate the cogeneration process applied to an apartment building in the Polanco area (Mexico). Considering the building’s electric, thermal demand and consumption data, the cogeneration process model was simulated using Thermoflow© software [...] Read more.
The objective of this paper is to evaluate and to simulate the cogeneration process applied to an apartment building in the Polanco area (Mexico). Considering the building’s electric, thermal demand and consumption data, the cogeneration process model was simulated using Thermoflow© software (Thermoflow Inc., Jacksonville, FL, USA), in order to cover 1.1 MW of electric demand and to supply the thermal needs of hot water, heating, air conditioning and heating pool. As a result of analyzing various schemes of cogeneration, the most efficient scheme consists of the use of a gas turbine (Siemens model SGT-100-1S), achieving a cycle with efficiency of 84.4% and a heat rate of 14,901 kJ/kWh. The economic results of this evaluation show that it is possible to implement the cogeneration in the building with a natural gas price below US$0.014/kWh. The use of financing schemes makes the economic results more attractive. Furthermore, the percentage of the turbine load effect on the turbine load net power, cogeneration efficiency, chimney flue gas temperature, CO2 emission, net heat ratio, turbine fuel flow and after burner fuel flow was also studied. Full article
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Open AccessFeature PaperArticle Distilling Robust Design Principles of Biocircuits Using Mixed Integer Dynamic Optimization
Processes 2019, 7(2), 92; https://doi.org/10.3390/pr7020092
Received: 3 December 2018 / Revised: 24 January 2019 / Accepted: 31 January 2019 / Published: 13 February 2019
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Abstract
A major challenge in model-based design of synthetic biochemical circuits is how to address uncertainty in the parameters. A circuit whose behavior is robust to variations in the parameters will have more chances to behave as predicted when implemented in practice, and also [...] Read more.
A major challenge in model-based design of synthetic biochemical circuits is how to address uncertainty in the parameters. A circuit whose behavior is robust to variations in the parameters will have more chances to behave as predicted when implemented in practice, and also to function reliably in presence of fluctuations and noise. Here, we extend our recent work on automated-design based on mixed-integer multi-criteria dynamic optimization to take into account parametric uncertainty. We exploit the intensive sampling of the design space performed by a global optimization algorithm to obtain the robustness of the topologies without significant additional computational effort. Our procedure provides automatically topologies that best trade-off performance and robustness against parameter fluctuations. We illustrate our approach considering the automated design of gene circuits achieving adaptation. Full article
(This article belongs to the Special Issue Computational Synthetic Biology)
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Open AccessArticle Purification of Flavonoids from Mulberry Leaves via High-Speed Counter-Current Chromatography
Processes 2019, 7(2), 91; https://doi.org/10.3390/pr7020091
Received: 22 January 2019 / Revised: 2 February 2019 / Accepted: 3 February 2019 / Published: 13 February 2019
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Abstract
In order to obtain high-purity flavonoid products, the extracts from mulberry leaves were separated and purified via high-speed counter-current chromatography (HSCCC). Moreover, the product was detected via high-performance liquid chromatography (HPLC). The characteristic absorption wavelength of the rutin standard for HSCCC detection and [...] Read more.
In order to obtain high-purity flavonoid products, the extracts from mulberry leaves were separated and purified via high-speed counter-current chromatography (HSCCC). Moreover, the product was detected via high-performance liquid chromatography (HPLC). The characteristic absorption wavelength of the rutin standard for HSCCC detection and HPLC analysis at 257 nm was tested by ultraviolet scanning analysis. The effect of solvent systems and mobile phase flow rate on the separation efficiency were then researched. Finally, the solvent system of V(ethyl acetate):V(n-butanol):V(water) = 4:1:5 was selected as the operating system for HSCCC. This work theoretically analyzed the impact of the molecular structure and polarity of flavonoids on the choice of solvent systems. The results showed that the mobile phase flow rate had a great influence on the separation efficiency. Furthermore, the separation efficiency increased as the mobile phase flow rate decreased. When the mobile phase flow rate was 5 mL/min, the peak time for flavonoids was 140 min, the retention of the stationary phase was 56.4%, and the purity of the product reached 93.8%. The results of this study greatly improved the purity of flavonoids in mulberry leaf and provided a strong support for the separation and purification of mulberry leaf extract. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle Evaluation of Conditions Affecting Properties of Gac (Momordica Cocochinensis Spreng) Oil-Loaded Solid Lipid Nanoparticles (SLNs) Synthesized Using High-Speed Homogenization Process
Processes 2019, 7(2), 90; https://doi.org/10.3390/pr7020090
Received: 4 January 2019 / Revised: 2 February 2019 / Accepted: 3 February 2019 / Published: 12 February 2019
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Abstract
In this study, we attempted the preparation of gac oil-loaded solid lipid nanoparticles (SLNs) by the high-speed homogenization method using Naterol SE solid lipid, a cosmetic self-emulsifying base, and surfactant and investigated the effects of different conditions on the characteristics of the resulting [...] Read more.
In this study, we attempted the preparation of gac oil-loaded solid lipid nanoparticles (SLNs) by the high-speed homogenization method using Naterol SE solid lipid, a cosmetic self-emulsifying base, and surfactant and investigated the effects of different conditions on the characteristics of the resulting nanoparticles. The suspensions containing 5% active agents (gac-oil, w/w) were dispersed in a surfactant concentration of 5% (w/w) (Span 80:Tween 80 ratio of 28:72 w/w) and 2.5% (w/w) of solid lipid (Naterol SE) concentration. Suitable conditions for hot homogenization were 13,000 rpm, 60 min and 60 °C for speed, time and temperature, respectively. The suitable conditions for the subsequent cold homogenization were 25 min of homogenization time and 5 °C of temperature. The results showed that the mean size of SLNs-gac oil was 107 nm (measured by laser diffraction spectrometry, LDS), and dried size of SLNs-gac oil ranged from 50 to 80 nm (measured by transmission electron microscope, TEM). In addition, the study investigated the impact of gac oil content on the particle size of SLNs-gac oil and its stability under different storage conditions of UV radiation and storage temperature. At high storage temperatures, the color changes (ΔE) of the samples were more profound in comparison to that at the low storage temperature. The ΔE value of the blank sample (SLN-FREE gac-oil) was higher than that of the Gac oil-loaded SLNs samples (SLN-gac oil). Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle Sensor Fault-Tolerant Control Design for Mini Motion Package Electro-Hydraulic Actuator
Processes 2019, 7(2), 89; https://doi.org/10.3390/pr7020089
Received: 10 January 2019 / Revised: 8 February 2019 / Accepted: 9 February 2019 / Published: 12 February 2019
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Abstract
With the rapid development of computer science and information and communication technology (ICT), increasingly intelligent, and complex systems have been applied to industries as well as human life. Fault-tolerant control (FTC) has, therefore, become one of the most important topics attracting attention from [...] Read more.
With the rapid development of computer science and information and communication technology (ICT), increasingly intelligent, and complex systems have been applied to industries as well as human life. Fault-tolerant control (FTC) has, therefore, become one of the most important topics attracting attention from both engineers and researchers to maintain system performances when faults occur. The ultimate goal of this study was to develop a sensor fault-tolerant control (SFTC) to enhance the robust position tracking control of a class of electro-hydraulic actuators called mini motion packages (MMPs), which are widely used for applications requiring large force-displacement ratios. First, a mathematical model of the MMP system is presented, which is then applied in the position control process of the MMP system. Here, a well-known proportional, integrated and derivative (PID) control algorithm is employed to ensure the positional response to the reference position. Second, an unknown input observer (UIO) is designed to estimate the state vector and sensor faults using a linear matrix inequality (LMI) optimization algorithm. Then an SFTC is used to deal with sensor faults of the MMP system. The SFTC is formed of the fault detection and the fault compensation with the goal of determining the location, time of occurrence, and magnitude of the faults in the fault signal compensation process. Finally, numerical simulations were run to demonstrate the superior performance of the proposed approach compared to traditional tracking control. Full article
(This article belongs to the Section Other Topics)
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