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Records Added in March 2023
Records added in March 2023
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Showing records 1501 to 1525 of 12968. [First] Page: 57 58 59 60 61 62 63 64 65 Last
Using Peptidomics and Machine Learning to Assess Effects of Drying Processes on the Peptide Profile within a Functional Ingredient
Sweeny Chauhan, Sean O’Callaghan, Audrey Wall, Tomasz Pawlak, Ben Doyle, Alessandro Adelfio, Sanja Trajkovic, Mark Gaffney, Nora Khaldi
March 28, 2023 (v1)
Subject: Biosystems
Keywords: bioactive peptide, freeze-dry, functional ingredient, hydrolysate, Machine Learning, peptidomics, spray-dry
Bioactive peptides are known to have many health benefits beyond nutrition; yet the peptide profile of high protein ingredients has been largely overlooked when considering the effects of different processing techniques. Therefore, to investigate whether drying conditions could affect the peptide profile and bioactivity within a functional ingredient, we examined the effects of spray (SD) and freeze (FD) drying on rice natural peptide network (NPN), a characterised functional ingredient sourced from the Oryza sativa proteome, which has previously been shown to effectively modulate circulating cytokines and improve physical performance in humans. In the manufacturing process, rice NPN was either FD or SD. Employing a peptidomic approach, we investigated the physicochemical characteristics of peptides common and unique to FD and SD preparations. We observed similar peptide profiles regarding peptide count, amino acid distribution, weight, charge, and hydrophobicity in each sample. Additi... [more]
A Modified 2-DOF Control Framework and GA Based Intelligent Tuning of PID Controllers
Gun-Baek So
March 28, 2023 (v1)
Keywords: disturbance rejection, first-order processes with time delay model, Genetic Algorithm, PID controller, set-point weighting
Although a controller is well-tuned for set-point tracking, it shows poor control results for load disturbance rejection and vice versa. In this paper, a modified two-degree-of-freedom (2-DOF) control framework to solve this problem is proposed, and an optimal tuning method for the pa-rameters of each proportional integral derivative (PID) controller is discussed. The unique feature of the proposed scheme is that a feedforward controller is embedded in the parallel control structure to improve set-point tracking performance. This feedforward controller and the standard PID con-troller are combined to create a new set-point weighted PID controller with a set-point weighting function. Therefore, in this study, two controllers are used: a set-point weighted PID controller for set-point tracking and a conventional PID controller for load disturbance rejection. The parameters included in the two controllers are tuned separately to improve set-point tracking and load dis-turbance rejection p... [more]
Monitoring E. coli Cell Integrity by ATR-FTIR Spectroscopy and Chemometrics: Opportunities and Caveats
Jens Kastenhofer, Julian Libiseller-Egger, Vignesh Rajamanickam, Oliver Spadiut
March 28, 2023 (v1)
Keywords: ATR-FTIR spectroscopy, bioprocess monitoring, chemometrics, Machine Learning, process analytical technology, quality by design
During recombinant protein production with E. coli, the integrity of the inner and outer membrane changes, which leads to product leakage (loss of outer membrane integrity) or lysis (loss of inner membrane integrity). Motivated by current Quality by Design guidelines, there is a need for monitoring tools to determine leakiness and lysis in real-time. In this work, we assessed a novel approach to monitoring E. coli cell integrity by attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy. Various preprocessing strategies were tested in combination with regression (partial least squares, random forest) or classification models (partial least squares discriminant analysis, linear discriminant analysis, random forest, artificial neural network). Models were validated using standard procedures, and well-performing methods were additionally scrutinized by removing putatively important features and assessing the decrease in performance. Whereas the prediction of target... [more]
Centrifugal Filter-Assisted Block Freeze Crystallization Applied to Blueberry Juice
Patricio Orellana-Palma, María Guerra-Valle, Rommy N. Zúñiga
March 28, 2023 (v1)
Keywords: antioxidant capacity, blueberry juice, centrifugation, filter, freeze crystallization, physicochemical properties, polyphenolic compounds, preservation, process parameters
The impact of centrifugal-filter assisted block freeze crystallization (CFBFC) on the physicochemical parameters, total phenolic content (TPC), total anthocyanin content (TAC), and total flavonoid content (TFC), antioxidant activity (AA) and process parameters applied to blueberry juice was studied. Additionally, CFBFC was contrasted with gravitational BFC (GBFC) and centrifugal BFC (CBFC) techniques. For CFBFC process, the solutes values were ≈35.9 °Brix (fresh juice ≈13.8 °Brix), with a very dark red/purple color. Moreover, the bioactive components values presented a significant increase of 2.1, 2.0, 1.8, and 3.1 times compared to the initial TPC, TAC, TFC, and AA values, respectively, and these values were higher than GBFC and CBFC techniques. For efficiency, percentage of concentrate, and solute yield, CFBFC showed values close to 86%, 81%, and 0.9 (kg/kg), respectively, which were higher values than GBFC (48%, 38%, and 0.5 (kg/kg)) and CBFC (79%, 68%, and 0.7 (kg/kg)). Therefore,... [more]
The Role of Nanodispersed Catalysts in Microwave Application during the Development of Unconventional Hydrocarbon Reserves: A Review of Potential Applications
Alexey V. Vakhin, Mohammed Amine Khelkhal, Arash Tajik, Marat R. Gafurov, Oleg G. Morozov, Aydar R. Nasybullin, Sergey A. Karandashov, Andrey A. Ponomarev, Tatiana O. Krapivnitskaia, Mikhail Yu. Glyavin, Olga V. Slavkina, Konstantin A. Shchekoldin
March 28, 2023 (v1)
Subject: Materials
Keywords: asphaltenes, Catalysis, electromagnetic heating, heavy oil, in-situ upgrading, microwave, nano-metal particles, transitional metals
Electromagnetic impact on oil reservoir manifests itself in various physical and chemical phenomena and attracts a significant scientific and technological interest. Microwave (MW) radiation heating can be more efficient for the oil recovery than heat transfer by convection or by thermal conduction. MW influence can also lead to significant changes in the physicochemical and rheological properties of oil caused by chemical processes of transformation of the oil high-molecular components such as resins and asphaltenes. The efficiency of transition-metal catalysts applied for the in-situ conversion of hydrocarbons directly in the reservoir might be significantly increased by exposing the oil formation to MW radiation. Actually, transition metals nanoparticles and their oxides are considered as active absorbers of MW radiation and; therefore, they can be used to intensify MW impact on the reservoir. Catalyst particles dispersed in the formation provide enhanced MW sweep. Taken together, t... [more]
Experimental and Modeling of Dicamba Adsorption in Aqueous Medium Using MIL-101(Cr) Metal-Organic Framework
Hamza Ahmad Isiyaka, Khairulazhar Jumbri, Nonni Soraya Sambudi, Jun Wei Lim, Bahruddin Saad, Anita Ramli, Zakariyya Uba Zango
March 28, 2023 (v1)
Keywords: Adsorption, artificial neural network model, dicamba, metal-organic framework, response surface methodology
Drift deposition of emerging and carcinogenic contaminant dicamba (3,6-dichloro-2-methoxy benzoic acid) has become a major health and environmental concern. Effective removal of dicamba in aqueous medium becomes imperative. This study investigates the adsorption of a promising adsorbent, MIL-101(Cr) metal-organic framework (MOF), for the removal of dicamba in aqueous solution. The adsorbent was hydrothermally synthesized and characterized using N2 adsorption-desorption isotherms, Brunauer, Emmett and Teller (BET), powdered X-ray diffraction (XRD), Fourier Transformed Infrared (FTIR) and field emission scanning electron microscopy (FESEM). Adsorption models such as kinetics, isotherms and thermodynamics were studied to understand details of the adsorption process. The significance and optimization of the data matrix, as well as the multivariate interaction of the adsorption parameters, were determined using response surface methodology (RSM). RSM and artificial neural network (ANN) were... [more]
Simplified Reactor Design for Mixed Culture-Based Electrofermentation toward Butyric Acid Production
Paola Paiano, Giuliano Premier, Alan Guwy, Amandeep Kaur, Iain Michie, Mauro Majone, Marianna Villano
March 28, 2023 (v1)
Subject: Biosystems
Keywords: applied voltage, butyric acid, electrofermentation, mixed microbial cultures, single-chamber reactor
Mixed microbial culture (MMC) electrofermentation (EF) represents a promising tool to drive metabolic pathways toward the production of a specific compound. Here, the MMC-EF process has been exploited to obtain butyric acid in simplified membrane-less reactors operated by applying a difference of potential between two low-cost graphite electrodes. Ten values of voltage difference, from −0.60 V to −1.5 V, have been tested and compared with the experiment under open circuit potential (OCP). In all the tested conditions, an enhancement in the production rate of butyric acid (from a synthetic mixture of glucose, acetate, and ethanol) was observed, ranging from 1.3- to 2.7-fold relative to the OCP. Smaller enhancements in the production rate resulted in higher values of the calculated specific energy consumption. However, at all applied voltages, a low flow of current was detected in the one-chamber reactors, accounting for an average value of approximately −100 µA. These results hold a sub... [more]
Chemical Profiling of Pistacia lentiscus var. Chia Resin and Essential Oil: Ageing Markers and Antimicrobial Activity
Vasiliki K. Pachi, Eleni V. Mikropoulou, Sofia Dimou, Mariangela Dionysopoulou, Aikaterini Argyropoulou, George Diallinas, Maria Halabalaki
March 28, 2023 (v1)
Subject: Biosystems
Keywords: ageing, antibacterial, antifungal, chemical profile, Chios mastic, GC-MS, HPTLC, Pistacia lentiscus var. Chia, α-pinene, β-myrcene
Chios Mastic Gum (CMG) and Chios Mastic Oil (CMO) are two unique products of the tree Pistacia lentiscus var. Chia, cultivated exclusively on the Greek island of Chios. In the present study, the method proposed by the European Pharmacopoeia for mastic identification was employed using HPTLC together with an in-house method. A GC-MS methodology was also developed for the chemical characterization of CMOs. α-Pinene and β-myrcene were found in abundance in the fresh oils; however, in the oil of the aged collection, oxygenated monoterpenes and benzenoids such as verbenone, pinocarveol, and α-campholenal were found at the highest rates. Additionally, the antimicrobial activity of Chios Mastic Gums (CMGs) with their respective Chios Mastic Oils (CMOs) was evaluated, with growth tests against the fungi Aspergillus nidulans, Aspergillus fumigatus, Candida albicans, Mucor circinelloides, and Rhizopus oryzae, and the bacteria Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis, with t... [more]
Removal of Anionic and Cationic Dyes from Wastewater Using Activated Carbon from Palm Tree Fiber Waste
Basma G. Alhogbi, Shoruq Altayeb, Effat. A. Bahaidarah, Mahmoud F. Zawrah
March 28, 2023 (v1)
Subject: Environment
Keywords: activated carbon, Adsorption, anionic and cationic dyes, palm tree fiber wastes, recycles
This study focuses on using a facile method for the green preparation of activated carbon (AC) from palm tree fiber (PTF) waste. The synthesized cost-effective AC was investigated for the removal of an anionic dye (Congo red, CR) and a cationic dye (Rhodamine B, RhB) from wastewater. The morphological and structural characterization of the synthesized AC were performed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), surface area, Fourier transform infrared spectroscopy (FTIR), total pore volume, average pore diameter and pore size distribution, zeta potential, and zero-point charge. To investigate the adsorption efficiency, different parameters such as adsorbent dosage, solution pH, initial dye concentration, and duration were applied using the batch experiments. Various adsorption isotherm and kinetics models were applied to study the adsorption mechanism and dynamics. The results showed that chemical activation with a weak acid (H3PO4) at 400 °C for 30... [more]
Creating Values from Biomass Pyrolysis in Sweden: Co-Production of H2, Biocarbon and Bio-Oil
Ilman Nuran Zaini, Nanta Sophonrat, Kurt Sjöblom, Weihong Yang
March 28, 2023 (v1)
Keywords: Aspen Plus, biochar, bioenergy, hydrogen production, process simulation, Technoeconomic Analysis
Hydrogen and biocarbon are important materials for the future fossil-free metallurgical industries in Sweden; thus, it is interesting to investigate the process that can simultaneously produce both. Process simulations of biomass pyrolysis coupled with steam reforming and water-gas-shift to produce H2, biocarbon, and bio-oil are investigated in this work. The process simulation is performed based on a biomass pyrolysis plant currently operating in Sweden. Two co-production schemes are proposed: (1) production of biocarbon and H2, and (2) production of biocarbon, H2, and bio-oil. Sensitivity analysis is also performed to investigate the performance of the production schemes under different operating parameters. The results indicated that there are no notable differences in terms of the thermal efficiency for both cases. Varying the bio-oil condenser temperature only slightly changes the system’s thermal efficiency by less than 2%. On the other hand, an increase in biomass moisture conte... [more]
A Semi-Empirical Model for Predicting Frost Properties
Shao-Ming Li, Kai-Shing Yang, Chi-Chuan Wang
March 28, 2023 (v1)
Keywords: correlation, frost crystal, frost thermal conductivity, numerical model
In this study, a quantitative method for classifying the frost geometry is first proposed to substantiate a numerical model in predicting frost properties like density, thickness, and thermal conductivity. This method can recognize the crystal shape via linear programming of the existing map for frost morphology. By using this method, the frost conditions can be taken into account in a model to obtain the corresponding frost properties like thermal conductivity, frost thickness, and density for specific frost crystal. It is found that the developed model can predict the frost properties more accurately than the existing correlations. Specifically, the proposed model can identify the corresponding frost shape by a dimensionless temperature and the surface temperature. Moreover, by adopting the frost identification into the numerical model, the frost thickness can also be predicted satisfactorily. The proposed calculation method not only shows better predictive ability with thermal condu... [more]
Thermodynamics and Machine Learning Based Approaches for Vapor−Liquid−Liquid Phase Equilibria in n-Octane/Water, as a Naphtha−Water Surrogate in Water Blends
Sandra Lopez-Zamora, Jeonghoon Kong, Salvador Escobedo, Hugo de Lasa
March 28, 2023 (v1)
Keywords: Machine Learning, n-octane, number of phases, phase stability, vapor–liquid–liquid equilibrium, Water
The prediction of phase equilibria for hydrocarbon/water blends in separators, is a subject of considerable importance for chemical processes. Despite its relevance, there are still pending questions. Among them, is the prediction of the correct number of phases. While a stability analysis using the Gibbs Free Energy of mixing and the NRTL model, provide a good understanding with calculation issues, when using HYSYS V9 and Aspen Plus V9 software, this shows that significant phase equilibrium uncertainties still exist. To clarify these matters, n-octane and water blends, are good surrogates of naphtha/water mixtures. Runs were developed in a CREC vapor−liquid (VL_Cell operated with octane−water mixtures under dynamic conditions and used to establish the two-phase (liquid−vapor) and three phase (liquid−liquid−vapor) domains. Results obtained demonstrate that the two phase region (full solubility in the liquid phase) of n-octane in water at 100 °C is in the 10−4 mol fraction range, and it... [more]
Distribution-Independent Empirical Modeling of Particle Size Distributions—Coarse-Shredding of Mixed Commercial Waste
Karim Khodier, Renato Sarc
March 28, 2023 (v1)
Keywords: commercial waste, compositional data analysis, isometric log-ratios, mechanical processing, multivariate multiple linear regression, particle size distribution, shredder, simplex, waste treatment
Particle size distributions (PSDs) belong to the most critical properties of particulate materials. They influence process behavior and product qualities. Standard methods for describing them are either too detailed for straightforward interpretation (i.e., lists of individual particles), hide too much information (summary values), or are distribution-dependent, limiting their applicability to distributions produced by a small number of processes. In this work the distribution-independent approach of modeling isometric log-ratio-transformed shares of an arbitrary number of discrete particle size classes is presented. It allows using standard empirical modeling techniques, and the mathematically proper calculation of confidence and prediction regions. The method is demonstrated on coarse-shredding of mixed commercial waste from Styria in Austria, resulting in a significant model for the influence of shredding parameters on produced particle sizes (with classes: >80 mm, 30−80 mm, 0−30 mm... [more]
Enzymatic Synthesis of Poly(alkylene succinate)s: Influence of Reaction Conditions
Doris Pospiech, Renata Choińska, Daniel Flugrat, Karin Sahre, Dieter Jehnichen, Andreas Korwitz, Peter Friedel, Anett Werner, Brigitte Voit
March 28, 2023 (v1)
Subject: Materials
Keywords: aliphatic polyester, Candida antarctica, enzymatic polycondensation, enzyme activity, poly(butylene succinate)
Application of lipases (preferentially Candida antarctica Lipase B, CALB) for melt polycondensation of aliphatic polyesters by transesterification of activated dicarboxylic acids with diols allows to displace toxic metal and metal oxide catalysts. Immobilization of the enzyme enhances the activity and the temperature range of use. The possibility to use enzyme-catalyzed polycondensation in melt is studied and compared to results of polycondensations in solution. The experiments show that CALB successfully catalyzes polycondensation of both, divinyladipate and dimethylsuccinate, respectively, with 1,4-butanediol. NMR spectroscopy, relative molar masses obtained by size exclusion chromatography, MALDI-TOF MS and wide-angle X-ray scattering are employed to compare the influence of synthesis conditions for poly(butylene adipate) (PBA) and poly(butylene succinate) (PBS). It is shown that the enzymatic activity of immobilized CALB deviates and influences the molar mass. CALB-catalyzed polyco... [more]
Assessment of Heavy Metals in the Sediments of Chalan Beel Wetland Area in Bangladesh
Mohammad Abdus Salam, Mohammad Ashraful Alam, Sulav Indra Paul, Fatama Islam, Dinesh Chandra Shaha, Mohammad Mizanur Rahman, Mohammad Arifur Rahman Khan, Mohammad Mahbubur Rahman, Abul Kalam Mohammad Aminul Islam, Tofayel Ahamed, Golum Kibria Muhammad Mustafizur Rahman, Mohammad Giashuddin Miah, Abdul Mannan Akanda, Tofazzal Islam
March 28, 2023 (v1)
Keywords: contamination factor, dye complexes, ecological risk factor, enrichment factor, heavy metals
This study aimed to determine the levels and possible sources of heavy metals (HMs) in the sediments of Chalan beel (a large lake-like aquatic ecosystem) area located in the northwestern part of Bangladesh. The mean concentrations (mg kg−1) of two HMs, Cd (6.22) and Pb (51.39) exceeded the world normal averages (WNA), whereas the mean concentrations (mg kg−1) of Ni (60.46), Zn (10.75), Mn (8.64) and Cu (4.71) were below the WNA. The sediments showed significant enrichment with Cd, Pb and Ni in the studied area. The geo-accumulation index values of Cd (3.72) and Pb (0.76) were significantly higher in the sediments. The contamination factor and potential ecological risk index values of Cd and Pb revealed that Chalan beel was extremely and moderately contaminated by these heavy metals, respectively. Analysis of dye complexes used in handlooms around the Chalan beel areas revealed that mean concentrations of Cd and Pb exceeded the WNA. Furthermore, analyses of principal component, cluster... [more]
Improved Sugar Recovery from Orange Peel by Statistical Optimization of Thermo-Alkaline Pretreatment
Ye Won Jang, Kang Hyun Lee, Hah Young Yoo
March 28, 2023 (v1)
Keywords: alkaline, Biomass, enzymatic hydrolysis, Optimization, pretreatment
Orange peel, which is a by-product of oranges, contains carbohydrates that can be converted into sugars and used in the fermentation process. In this study, the thermal alkaline pretreatment process was chosen because of its simplicity and lesser reaction time. In addition, the reaction factors were optimized using response surface methodology. The determined optimal conditions were as follows: 60.1 g/L orange peels loading, 3% KOH and 30 min. Under the optimal conditions, glucan content (GC) and enzymatic digestibility (ED) were found to be 32.8% and 87.8%, respectively. Enzymatic hydrolysis was performed with pretreated and non-pretreated orange peels using three types of enzyme complex (cellulase, cellobiase and xylanase). The minimum concentrations of enzyme complex required to obtain maximum ED were 30 FPU (filter paper unit), 15 CBU (cellobiase unit), and 30 XNU (xylanase unit) based on 1 g-biomass. Additionally, ED of the treated group was approximately 3.7-fold higher than that... [more]
Production Flow Analysis in a Semiconductor Fab Using Machine Learning Techniques
Ivan Kristianto Singgih
March 28, 2023 (v1)
Keywords: digital twin, Machine Learning, production control, semiconductor fab, Simulation
In a semiconductor fab, wafer lots are processed in complex sequences with re-entrants and parallel machines. It is necessary to ensure smooth wafer lot flows by detecting potential disturbances in a real-time fashion to satisfy the wafer lots’ demands. This study aims to identify production factors that significantly affect the system’s throughput level and find the best prediction model. The contributions of this study are as follows: (1) this is the first study that applies machine learning techniques to identify important real-time factors that influence throughput in a semiconductor fab; (2) this study develops a test bed in the Anylogic software environment, based on the Intel minifab layout; and (3) this study proposes a data collection scheme for the production control mechanism. As a result, four models (adaptive boosting, gradient boosting, random forest, decision tree) with the best accuracies are selected, and a scheme to reduce the input data types considered in the models... [more]
Plastic Bending at Large Strain: A Review
Sergei Alexandrov, Elena Lyamina, Yeong-Maw Hwang
March 28, 2023 (v1)
Subject: Materials
Keywords: bending tests, bending under tension, plastic bending, pure bending, semi-analytic solutions
Finite plastic bending attracts researchers’ attention due to its importance for identifying material properties and frequent occurrence in sheet metal forming processes. The present review contains theoretical and experimental parts. The theoretical part is restricted to analytic and semi-analytic solutions for pure bending and bending under tension. The experimental part mainly focuses on four-point bending, though other bending tests and processes are also outlined.
Effects of the Feeding Solution Composition on a Reductive/Oxidative Sequential Bioelectrochemical Process for Perchloroethylene Removal
Edoardo Dell’Armi, Marco Zeppilli, Bruna Matturro, Simona Rossetti, Marco Petrangeli Papini, Mauro Majone
March 28, 2023 (v1)
Subject: Environment
Keywords: bioelectrochemical systems, bioremediation, oxidative dechlorination, reductive dechlorination
Chlorinated aliphatic hydrocarbons (CAHs) are common groundwater contaminants due to their improper use in several industrial activities. Specialized microorganisms are able to perform the reductive dechlorination (RD) of high-chlorinated CAHs such as perchloroethylene (PCE), while the low-chlorinated ethenes such as vinyl chloride (VC) are more susceptible to oxidative mechanisms performed by aerobic dechlorinating microorganisms. Bioelectrochemical systems can be used as an effective strategy for the stimulation of both anaerobic and aerobic microbial dechlorination, i.e., a biocathode can be used as an electron donor to perform the RD, while a bioanode can provide the oxygen necessary for the aerobic dechlorination reaction. In this study, a sequential bioelectrochemical process constituted by two membrane-less microbial electrolysis cells connected in series has been, for the first time, operated with synthetic groundwater, also containing sulphate and nitrate, to simulate more rea... [more]
Improving Low Rank Coal Flotation Using a Mixture of Oleic Acid and Dodecane as Collector: A New Perspective on Synergetic Effect
Maoyan An, Yinfei Liao, Yijun Cao, Xiaodong Hao, Longfei Ma
March 28, 2023 (v1)
Keywords: low rank coal, mixed collector, supramolecular structure, synergetic mechanism
The mixed collector can improve low rank coal flotation efficiency, but its synergistic mechanism needs to be further explored. In this paper, oleic acid-dodecane (OA-D), oleic acid (OA), and dodecane (D) were employed to treat the low rank coal for revealing new synergistic mechanism of the mixed collector. First the surface free energy of the coal, the surface free energy of coal-water and coal-water-coal were calculated. Then wetting heat measurement, X-ray Photoelectron Spectroscopy (XPS) and FTIR were used to analyze synergistic mechanism of the mixed collector in depth. The results showed that OA-D obtained a higher combustible recovery than using OA and D, respectively. The essence of synergetic mechanism of OA-D was that they formed a relatively ordered “supramolecular structure” on the low rank coal surface, especially there were hydrophobic and van der Waals forces between the oleic acid chain and the dodecane chain that can promote the formation of a continuous collector fil... [more]
Influence of Loading Rate on the Energy Evolution Characteristics of Rocks under Cyclic Loading and Unloading
Jielin Li, Liu Hong, Keping Zhou, Caichu Xia, Longyin Zhu
March 28, 2023 (v1)
Subject: Materials
Keywords: cyclic loading and unloading, damping ratio, elastic energy index, energy evolution, loading rate, plastic strain
To analyse the effect of loading rate on the energy evolution of rocks under cyclic loading and unloading, tests on saturated limestone were conducted at loading rates of 0.15, 0.2, and 0.3 mm/min, and the evolution characteristics of plastic, elastic, dissipation, and input energies were examined under different loading rates. The results indicated that the plastic strain in the entire test was directly proportional to the loading rate. In addition, strength, residual stress, plastic energy, and dissipation energy under residual resistance were inversely proportional to the loading rate. The plastic strain exhibited a decreasing−stabilising−increasing trend, and the smaller loading rate delayed the “increasing” trend. The increasing extent of each energy exhibited the following trend: input > elastic > plastic > dissipation energy. Furthermore, the first three types of energy exhibited a slow−fast−slow−fast increase trend. The dissipation energy exhibited a fast−steady−fast−slow−fast... [more]
Modular Permanent Magnet Synchronous Machine with Low Space Harmonic Content
Keyi Wang, Heyun Lin
March 28, 2023 (v1)
Subject: Other
Keywords: dual three-phase, modular machine, permanent magnet synchronous machine, space harmonic, two-slot pitch
Modularity technique is desirable in large permanent magnet synchronous machines (PMSMs) because it facilitates manufacture, assembly, and maintenance. Although the PMSMs with fractional-slot concentrated windings (FSCWs) allow their stators to be modularized, they usually suffer from high nonworking space harmonic content. The PMSMs with various reported two-slot pitch windings (TSPWs) show much lower nonworking space harmonic content, but they do not support stator modularity. This paper proposes a modular PMSM with a special dual three-phase (DTP) TSPW, which exhibits quite low nonworking space harmonic content. First, the topology of the proposed machine is described in detail. Then, the mechanism of reducing the nonworking space harmonic content of the machine is expounded through winding magnetomotive force (MMF) analysis. Finally, the electromagnetic characteristics of a specific proposed modular PMSM and a conventional modular PMSM with DTP-FSCW are compared by finite element m... [more]
Potential of Thermal Energy Storage for a District Heating System Utilizing Industrial Waste Heat
Hanne Kauko, Daniel Rohde, Brage Rugstad Knudsen, Terje Sund-Olsen
March 28, 2023 (v1)
Keywords: district heating, industrial waste heat recovery, thermal energy storage
The potential for utilizing industrial waste heat for district heating is enormous. There is, however, often a temporal mismatch between the waste heat availability and the heating demand, and typically fossil-based peak boilers are used to cover the remaining heat demand. This study investigates the potential of applying a thermal energy storage tank at the district heating supply system at Mo Industrial Park in Norway, where waste heat from the off-gas of a ferrosilicon production plant is the main heating source. To cover peak heating demands, boilers based on CO gas, electricity, and oil are applied. The reduction in peak heating costs and emissions is evaluated as a function of tank size for two different scenarios: (1) a scenario where CO gas, which is a byproduct from another nearby industry, is the main peak heating source; and (2) a scenario where no CO gas is available, and electricity is the main peak heating source. The highest economic viability is obtained with the smalle... [more]
The Effects of Oil and Gas Risk Factors on Malaysian Oil and Gas Stock Returns: Do They Vary?
Mohammad Enamul Hoque, Soo-Wah Low, Mohd Azlan Shah Zaidi
March 28, 2023 (v1)
Subject: Energy Policy
Keywords: asset pricing, Malaysian stock market, oil and gas industry, oil and gas risk factor
This study explores Malaysian oil and gas stocks’ exposure to oil and gas risk factors, paying special attention to subindustry classification, stock size, book-to-market value, and volatility state. The study employs firm-level weekly frequency data of oil and gas firms and several multi-asset pricing models within a GARCH (1,1)-X and Markov-switching framework. The empirical findings reveal that oil price, gas price, and exchange rate exhibit positive effects on the stock returns of all oil and gas sub-industries, but they exhibit negative effects on gas utilities sub-industry stock returns. The empirical findings also reveal that the extent of this effect varies across sub-industry, stock size, book-to-market value, and volatility states. Thus, the findings suggest the existence of asymmetric, heterogeneous, and non-linear exposures.
Influence of the Size and Shape of Magnetic Core on Thermal Parameters of the Inductor
Kalina Detka, Krzysztof Górecki
March 28, 2023 (v1)
Subject: Other
Keywords: ferromagnetic cores, inductors, self-heating, thermal model, thermal resistance, transient thermal impedance
In this paper, a new thermal model of the inductor is proposed. This model takes into account self-heating in the core and in the winding, and mutual thermal couplings between the mentioned components of the inductor. The form of the elaborated thermal model is presented. In this model, the influence of power dissipated in the core and in the winding of the inductor on the efficiency of heat removal is taken into account. Correctness of the model is verified experimentally for inductors containing ferrite cores of different shapes and dimensions. The good agreement between the results of calculations and measurements is obtained. On the basis of the obtained findings, the influence of volume and the shape of the core on thermal resistances and thermal capacitances occurring in this model is discussed.
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