bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural and Spectroscopic Characteristics of NiII and CuII Complexes with Poly (Vinyl Alcohol-Nicotinic Acid) Copolymers for Photocatalytic Degradation of Indigo Carmine Dye
Authors: Ali Ibraheem O. , Nassar Hisham S. , Naglah Ahmed M. , Al-Harbi Laila M. , Elhenawy Ahmed A.
Published: October 2021

Poly-vinyl-alcohol (PVA) has been cross-linked chemically with nicotinic-acid (NA) in an aqueous medium. The copolymers were complexed with NiII and CuII ions. The complexes and copolymers were analyzed using FT-IR and UV–Visible spectroscopy, XRD and TGA, but copolymers were extra analyzed with nuclear magnetic resonance (1H NMR). FT-IR spectra of copolymer revealed the presence of C=O & C–N groups due to the esterification of PVA-NA. The Cu/NA-PVA formed via bidentate interaction of the pyridinyl and carboxyl of NA. EPR/UV-vis data shows the square-planar geometry for NiII and CuII complexes. The adsorption of IC dye onto CuII/NA-PVA complex was noticeably greater (90%) in 35 min than NiII/NA-PVA. The DFT\B3LYP with 6- 311G* quantum chemical calculations were carried out for tested compounds. The DFT was conducted to examine an interaction mode of the target compounds with the reaction system. The QSPR was calculated as: optimization geometries, (FMOs), chemical-reactivities and NLO for the copolymers. The (MEPs) were figured to predict the interaction behavior of the ligand and its complexes.
Low-Threshold and Wavelength-Tunable InGaN Tubular WGM Laser Embedded in a Flexible Substrate
Authors: Hu Peng , Li Yufeng , Zhang Shengnan , Zhang Ye , Tian Zhenhuan , Yun Feng
Published: October 2021

We have fabricated a tubular whispering gallery mode laser based on InGaN/GaN quantum wells and transferred it onto a flexible substrate. Compared with those without the transferring processes, the threshold energy density was reduced by 60%, at about 25.55 µJ/cm2, while a high-quality factor of >15,000 was obtained. Finite-difference time-domain simulation demonstrated that such a low threshold energy density can be attributed to the decreased mode volume, from 1.32 × 10−3 μm3 to 6.92 × 10−4 μm3. The wavelength dependences on strain were found to be 5.83 nm, 1.38 nm, and 2.39 nm per stretching unit ε in the X, Y, and Z directions, respectively. Such strain sensitivity was attributed to the deformation of the GaN microtube and the change in the refractive index of the PDMS.
HPV16-Genotyper: A Computational Tool for Risk-Assessment, Lineage Genotyping and Recombination Detection in HPV16 Sequences, Based on a Large-Scale Evolutionary Analysis
Authors: Nikolaidis Marios , Tsakogiannis Dimitris , Bletsa Garyfalia , Mossialos Dimitris , Kottaridi Christine , Iliopoulos Ioannis , Markoulatos Panayotis , Amoutzias Grigoris D.
Published: October 2021

Previous analyses have identified certain but limited evidence of recombination among HPV16 genomes, in accordance with a general perception that DNA viruses do not frequently recombine. In this evolutionary/bioinformatics study we have analyzed more than 3600 publicly available complete and partial HPV16 genomes. By studying the phylogenetic incongruence, similarity plots and the distribution patterns of lineage-specific SNPs, we identify several potential recombination events between the two major HPV16 evolutionary clades. These two clades comprise the (widely considered) phenotypically more benign (lower risk) lineage A and the (widely considered) phenotypically more aggressive (higher risk) non-European lineages B, C and D. We observe a frequency of potential recombinant sequences ranging between 0.3 and 1.2% which is low, but nevertheless considerable. Our findings have clinical implications and highlight that HPV16 genotyping and risk assessment based only on certain genomic regions and not the entire genome may provide a false genotype and, therefore, its associated risk estimate. Finally, based on this analysis, we have developed a bioinformatics tool that automates the entire process of HPV16 lineage genotyping, recombination detection and further identifies, within the submitted sequences, SNPs that have been reported in the literature to increase the risk of cancer.
Prenatal Noninvasive Trio-WES in a Case of Pregnancy-Related Liver Disorder
Authors: Provenzano Aldesia , Farina Antonio , Seidenari Anna , Azzaroli Francesco , Serra Carla , Della Gatta Anna , Zuffardi Orsetta , Giglio Sabrina Rita
Published: October 2021

Liver disease in pregnancy may present as an acute condition related to the gestational period, characterized by pruritus, jaundice, and abnormal liver function. The disease may be misdiagnosed with other liver diseases, some of which may have consequences for fetal health. It is therefore advisable to implement rapid diagnostic strategies to provide information for the management of pregnancy in these conditions. We report the case of a healthy woman with a twin pregnancy from homologous in vitro fertilization (IVF), who in the third trimester presented jaundice and malaise. Biochemical investigations and liver hyperechogenicity raised the suspicion of acute fatty liver disease of pregnancy (AFLP). Non-invasive prenatal whole-exome sequencing (WES) in the trio identified the Phe305Ile heterozygous variant in the ATP8B1 gene. Considering the twin pregnancy, the percentage of the variant versus the wild allele was of 31%, suggesting heterozygosity present in the mother alone. This analysis showed that the mother was affected by benign recurrent intrahepatic cholestasis of pregnancy (ICP1: # 147480) and indicated the opportunity to anticipate childbirth to avoid worsening of the mother’s health. WES after the birth of the twins confirmed the molecular data.
Pentraxin-3 Is a Strong Biomarker of Sepsis Severity Identification and Predictor of 90-Day Mortality in Intensive Care Units via Sepsis 3.0 Definitions
Authors: Chen Huan , Li Tao , Yan Shanshan , Liu Meidong , Liu Ke , Zhang Huali , Gao Min , Xiao Xianzhong
Published: October 2021

Background: Sepsis is the leading cause of mortality in intensive care units (ICUs). However, early diagnosis and prognosis of sepsis and septic shock are still a great challenge. Pentraxin-3 (PTX3) was shown to be associated with the severity and outcome of sepsis and septic shock. This study was carried out to investigate the diagnostic and prognostic value of PTX3 in patients with sepsis and septic shock based on Sepsis 3.0 definitions. Methods: In this single-center prospective observational study, all patients’ serum was collected for biomarker measurements within 24 h after admission. Logistic and Cox regression analyses were used to identify the potential biomarkers of diagnosis, severity stratification, and prediction. Results: Serum levels of PTX3 were significantly increased on the first day of ICU admission, while septic shock patients had highest PTX3 levels than other groups. A combination between PTX3 and procalcitonin (PCT) could better discriminate sepsis and septic shock, and PTX3 was an independent predictor of mortality in sepsis and septic shock patients. Conclusion: PTX3 may be a robust biomarker to classify the disease severity and predict the 90-day mortality of sepsis and septic shock based on the latest Sepsis 3.0 definitions.
Usefulness of an Endodontic Case Difficulty Assessment Form of Root Canal Treatments in Dental Education in Finland
Authors: Pesonen Reetta , Tanner Tarja , Käkilehto Taina , Oikarinen-Juusola Kristiina , Laitala Marja-Liisa , Anttonen Vuokko
Published: October 2021

According to current care guidelines, it would be beneficial to evaluate the difficulty of a root canal treatment (RCT) after the decision of an indicated RCT. For this matter, several difficulty assessment forms have been developed. In this pilot study, fifth-year dental students evaluated the usefulness of the Endodontic Case Difficulty Assessment Form (ECAF) presented in the Finnish Current Care Guidelines for Endodontic Treatment (2014). Another aim was to postoperatively investigate how well the evaluation by dental students using the ECAF associated with the outcome of RCT evaluated by a specialist in endodontics. The dental students’ (n = 33) and the supervisor’s assessments of the RCTs were compared postoperatively at the Dental Educational Unit, Oulu, Finland. After completing the ECAF, the students’ experiences of its use were explored with a structured form. In ECAF, patient-derived factors, such as gagging, deviant crown morphology, and complications in previous endodontic treatment, were all significantly associated with complications in RCTs by the dental students (p < 0.05). The assessments by students and the supervisor differed in 55% of cases, especially in moderately difficult cases. In the majority of these cases (71%), the students evaluated the case to be easier than the teacher. Students found the ECAF user-friendly, even if it did not demonstrate their competence in accomplishing RCTs. The ECAF appears useful for junior dentists, specifically in terms of distinguishing the least and most difficult cases. A simpler form could be useful for students and clinicians.
A Multi-Modal Fusion Method Based on Higher-Order Orthogonal Iteration Decomposition
Authors: Liu  Fen , Chen  Jianfeng , Tan  Weijie , Cai  Chang
Published: October 2021

Multi-modal fusion can achieve better predictions through the amalgamation of information from different modalities. To improve the performance of accuracy, a method based on Higher-order Orthogonal Iteration Decomposition and Projection (HOIDP) is proposed, in the fusion process, higher-order orthogonal iteration decomposition algorithm and factor matrix projection are used to remove redundant information duplicated inter-modal and produce fewer parameters with minimal information loss. The performance of the proposed method is verified by three different multi-modal datasets. The numerical results validate the accuracy of the performance of the proposed method having 0.4% to 4% improvement in sentiment analysis, 0.3% to 8% improvement in personality trait recognition, and 0.2% to 25% improvement in emotion recognition at three different multi-modal datasets compared with other 5 methods.
Control Methods for Performance Improvement of an Integrated On-Board Battery Charger in Hybrid Electric Vehicles
Authors: Bak Yeongsu , Kang Ho-Sung
Published: October 2021

This paper presents control methods for performance improvement of an integrated on-board battery charger (OBC) in hybrid electric vehicles (HEVs). HEVs generally consist of an OBC and a starter generator system (SGS). Since these each have a power conversion device for independent operation, such as battery charging and starter generator driving for engine starting, it necessarily increases the number of components, weight, and volume of the HEV. In order to overcome these disadvantages, recent research concerning the integrated OBC has progressed. Although it demands installation of power relays and an additional circuit, the integrated OBC is effectively operated for battery charging and starter generator driving. This paper proposes not only a harmonic reduction method of grid current, but also a feed-forward control method for performance improvement of the integrated OBC in HEVs. The effectiveness of the proposed control methods is verified by simulation and experimental results.
Control Strategies for Energy Efficiency at PNU’s Metro System
Authors: Saleh Wafaa , Justin Shekaina , Alsawah Ghada , Al Ghamdi Tasneem , Lashin Maha M. A.
Published: October 2021

It is broadly acknowledged that there is an urgent need to reduce carbon-based mobility systems and increase renewable energy alternatives. The automotive industry is one of the greatest consumers of energy in the world. It is fronted with many challenges that aim at reducing carbon emissions. Renewable energy costs are getting cheaper and more cost effective. However, well devised design and control strategies are also needed in order to optimize any systems that are adopted in this field. Previous research shows that the energy consumption for non-traction purposes may be of the same scale as the energy used to move rolling stock, and in some cases even larger. The Kingdom of Saudi Arabia is very interested in the implementation of policies that aim at reducing energy consumption and encouraging renewable energy programs. Under its Vision 2030 development program, the Kingdom of Saudi Arabia is looking to produce 30% of its energy from renewables and other sources, with solar energy playing an important role. The work presented in this paper is aimed at an investigation of design and control strategies to reduce energy consumption and to propose a cleaner source of energy to power Princess Nourah Bint Abdulrahman University’s Automated People Mover (PNU-APM). Two areas of applications have been investigated for adopting these types of technology. Firstly, a p-v solar energy option that could be adopted for implementation in potential applications since the metro system is already in full operation using electricity. Secondly, design and control strategies including exploiting solar energy for a metro operation are discussed and investigated. A number of strategies to reduce heating, ventilation, and air conditioning (HVAC) load, which happens to be the biggest energy consumer, have been discussed. Results show great potential in energy savings with adopting p-v solar sources as well as implementation of few suggested control strategies. Some deliberations of some of the drawbacks of solar energy are also offered.
Investigation of the Performances of a Diesel Engine Operating on Blended and Emulsified Biofuels from Rapeseed Oil
Authors: Markov Vladimir Anatolyevich , Sa Bowen , Devyanin Sergey Nikolaevich , Zherdev Anatoly Anatolyevich , Vallejo Maldonado Pablo Ramon , Zykov Sergey Anatolyevich , Denisov Aleksandr Dmitrievich , Ambawatte Hewage Chithral
Published: October 2021

The article discusses the possibility of using blended biofuels from rapeseed oil (RO) as fuel for a diesel engine. RO blended diesel fuel (DF) and emulsified multicomponent biofuels have been investigated. Fuel physicochemical properties have been analyzed. Experimental tests of a diesel engine D-245 in the operating conditions of the external characteristic curve and the 13-mode test cycle have been conducted to investigate the effect of these fuels on engine performances. CFD simulations of the nozzle inner flow were performed for DF and ethanol-emulsified RO. The possibility of a significant improvement in brake thermal efficiency of the engine has been noted. The efficiency of using blended biofuels from RO as a motor fuel for diesel engines has been evaluated based on the experimental test results. It was shown that in comparison with the presence of RO in emulsified multicomponent biofuel, the presence of water has a more significant effect on NOx emission reduction. The content of RO and the content of water in the investigated emulsified fuels have a comparable influence on exhaust smoke reduction. Nozzle inner flow simulations show that the emulsification of RO changes its flow behaviors and cavitation regime.
Research on Dynamic Identification of Servo Motor Load Inertia Based on the Error Gain Factor Model
Authors: Xie Fang , Yu Fei , An Chaochen
Published: October 2021

Aiming at solving the problems of slow motion and positioning deviation caused by the change of the moment of inertia of the servo motor due to different loads, an identification method for the moment of inertia on the basis of the error gain factor model is introduced into the controller, so that the moment of inertia can be obtained accurately and quickly under dynamic conditions. First, the electromagnetic and motion equation of the permanent magnet synchronous motor is built, and the logical relationship between the moment of inertia, torque, speed and other physical quantities is derived, so that the moment of inertia can be dynamically acquired. Second, in order to increase the identification accuracy, an adaptive function is introduced in the inertia identification model to replace the fixed parameters as an error gain factor (EGF). Third, the accuracy parameter is defined, and the identification algorithm on the basis of the EGF model is compared with the accuracy parameters of the existing identification method, which verifies that the improved algorithm has a better accuracy and speed. Finally, on the experimental platform, the working condition of unsteady speed is simulated. It is further verified that the proposed method has a high anti-interference capability.
Model Predictive Controller Design for Vehicle Motion Control at Handling Limits in Multiple Equilibria on Varying Road Surfaces
Authors: Czibere Szilárd , Domina Ádám , Bárdos Ádám , Szalay Zsolt
Published: October 2021

Electronic vehicle dynamics systems are expected to evolve in the future as more and more automobile manufacturers mark fully automated vehicles as their main path of development. State-of-the-art electronic stability control programs aim to limit the vehicle motion within the stable region of the vehicle dynamics, thereby preventing drifting. On the contrary, in this paper, the authors suggest its use as an optimal cornering technique in emergency situations and on certain road conditions. Achieving the automated initiation and stabilization of vehicle drift motion (also known as powerslide) on varying road surfaces means a high level of controllability over the vehicle. This article proposes a novel approach to realize automated vehicle drifting in multiple operation points on different road surfaces. A three-state nonlinear vehicle and tire model was selected for control-oriented purposes. Model predictive control (MPC) was chosen with an online updating strategy to initiate and maintain the drift even in changing conditions. Parameter identification was conducted on a test vehicle. Equilibrium analysis was a key tool to identify steady-state drift states, and successive linearization was used as an updating strategy. The authors show that the proposed controller is capable of initiating and maintaining steady-state drifting. In the first test scenario, the reaching of a single drifting equilibrium point with −27.5° sideslip angle and 10 m/s longitudinal speed is presented, which resulted in −20° roadwheel angle. In the second demonstration, the setpoints were altered across three different operating points with sideslip angles ranging from −27.5° to −35°. In the third test case, a wet to dry road transition is presented with 0.8 and 0.95 road grip values, respectively.
Aluminium Nitride Doping for Solar Mirrors Self-Cleaning Coatings
Authors: Castaldo Anna , Gambale Emilia , Vitiello Giuseppe
Published: October 2021

Soiling severely reduces solar mirror performance, requiring dispendious water consumption for cleaning operations and causing an increase in the levelized cost of energy (LCOE). An emerging technology for facing this problem consists of developing transparent self-cleaning coatings, able to be washed with a small amount of water by virtue of the modulation of surficial wetting properties. Nevertheless, the beneficial effects of coatings decrease in the first year, and coated mirrors show even higher soiling than non-coated ones. Moreover, it is important that coating production processes are economically convenient, consistent with the intended reduction of overall costs. The aim of this work is the research and development of a cheap and scalable solution, compatible with mirror fabrication steps and, in such a sense, economically advantageous. It involves the substitution of the alumina last layer of solar mirrors with more hydrophobic, potentially auxetic aluminum compounds, such as nitrides. In particular, 2D inorganic aluminum nitride thin films doped with metals (such as aluminum and silver) and non-metals have been fabricated by means of reactive sputtering deposition and characterized for the purpose of studying their self-cleaning behavior, finding a trade-off between wetting properties, optical clarity, and stability.
Improving the Efficiency of Oil and Gas Wells Complicated by the Formation of Asphalt–Resin–Paraffin Deposits
Authors: Nurgalieva Karina Shamilyevna , Saychenko Liliya Albertovna , Riazi Masoud
Published: October 2021

A number of difficulties may be encountered in the final stages of oil field exploitation, including the formation of asphalt–resin–paraffin deposits (ARPDs). It is expedient to use complex technologies to remove the already formed deposits and prevent the formation of ARPDs. This paper focuses on the complex technology of oil field exploitation. This technology combines both the removal of organic deposits and the prevention of the formation of these deposits in the well bottomhole formation zone (BHFZ) system. The calculations for determining the process parameters of selling the ARPD inhibitor solution into the BHFZ are presented in this article. This complex technology includes the process of ARPD removal by flushing the well and the subsequent injection of the developed ARPD solvent into the BHFZ. In addition, the technology is complemented by a method of preventing the formation of these deposits. This method consists of squeezing the ARPD inhibitor and then pumping it by the selling fluid from five to ten times of the volume. This article contains a detailed calculation of the methodology and provides the diagrams for the solvent and inhibitor injection.
Identification of the Technical Condition of Induction Motor Groups by the Total Energy Flow
Authors: Koteleva N. I. , Korolev N. A. , Zhukovskiy Y. L.
Published: October 2021

The paper discusses the method of identifying the technical condition of induction motors by classifying the energy data coming from the main common power bus. The work shows the simulation results of induction motor operation. The correlation between occurring defects and current diagrams is presented. The developed simulation model is demonstrated. The general algorithm for conducting experiments is described. Five different experiments to develop an algorithm for the classification are conducted: determination of the motors number in operation with different power; determination of the motors number in operation with equal power; determination of the mode and load of induction electric motor; determination of the fault and its magnitude with regard to operation and load of induction motor; determination of the fault and its magnitude with regard to operation and load of induction motor with regard to non-linear load in the flow. The article also presents an algorithm for preprocessing data to solve the classification problem. In addition, the classification results are shown and recommendations for testing and using the classification algorithm on a real object are made.
Health Benefits from Renewable Electricity Sources: A Review
Authors: Silva Susana , Laranjeira Erika , Soares Isabel
Published: October 2021

Energy generation has had several negative health impacts over the last few decades, mainly due to air pollution. One of the ways to decrease such impacts is to increase energy generation through renewable energy sources (RESs). These sources have important health co-benefits that need to be taken into consideration. This topic has been included in the literature, but research is scattered. The goal of this article is to show the status of the literature on this topic. We performed a systematic literature review on the health co-benefits of RES use, depicting the state of the art of this literature, some common findings, limitations, and lines for future research. It is clear from our analysis that this literature remains scarce. We found 28 studies fitting the inclusion criteria. Results can be summed as follows: (1) wind and solar power are the most studied RES sources; (2) most studies are for the United States and developing countries are largely understudied; and (3) health benefit results vary widely according to site-specific conditions. Overall, the existing studies show significant health co-benefits from RES use, which are important to consider when performing cost–benefit analysis for energy projects. This is particularly relevant for policy-makers and energy investors.
Low-Speed Transient and Steady-State Performance Analysis of IPMSM for Nonlinear Speed Regulator with Effective Compensation Scheme
Authors: Usama Muhammad , Kim Jaehong
Published: October 2021

The speed response of the interior permanent magnet synchronous motor (IPMSM) drive at low speeds was analyzed. To eliminate the effect of external disturbance or parameter uncertainty, a nonlinear speed control loop was designed based on the sliding-mode exponential reaching law, which reduces chatter, which is the major drawback of the constant reaching law sliding-mode control technique. The proposed nonlinear speed control eliminates speed ripples at low speed under load disturbance. The problem of speed convergence at low speed is caused by electromagnetic torque ripples, which cause shaft speed oscillations that affect drive performance. The main objective of the proposed method is to change the traditional IPMSM control design by compensating with an appropriate signal along the reference current and across the output of the speed control loop. To optimize the speed tracking performance during disturbances or parametric variations, a nonlinear speed control scheme is designed that can vigorously adapt to the change in the controlled system. The comparative analysis shows that the method provides excellent transient performance (e.g., fast convergence response, less overshoot, and fast settling time) and standstill performance (e.g., reduced steady-state error) compared with conventional control methods at low speed under varying load conditions. The method is easy to implement and does not require additional computational cost. To demonstrate the effectiveness and feasibility of the design approach, a numerical analysis was conducted, and the control scheme was verified using MATLAB/Simulink considering various operating conditions.
A Power Control Method for Hybrid Electrical Accommodation Systems
Authors: Nguyen-Van Triet
Published: October 2021

This paper presents a power control method for a hybrid electrical system, which enhances a conventional main AC grid by adding a DC sub-grid in parallel. In this system, each prosumer connects to the sub-grid via a couple of half-bridge inverters of a device called a power router. All of the power routers connected to the sub-grid are controlled such that they maintain the voltage of the sub-grid equally, which is an essential feature of peer-to-peer power accommodation without synchronization. This paper proposes an adaptive hysteresis current-control technique for controlling sub-grid-connected inverters that maintains the voltage of the sub-grid while accommodating a given power. The proposed control method also balances currents between positive and negative lines of the sub-grid simultaneously. The proposed control method is implemented on a high-speed FPGA-based digital controller and is evaluated on three prototypes of the power router. The experimental results show that the proposed method yields fast and stable responses and enables the power router to accommodate power with a high accuracy.
Investigations on Pressure Fluctuations in the S-Shaped Region of a Pump–Turbine
Authors: Wang Hongjie , Wang Jianpeng , Gong Ruzhi , Shang Chaoying , Li Deyou , Wei Xianzhu
Published: October 2021

Hydraulic pumped storage is a special power generation and electricity shortage technology, which is usually operated with thermal power and nuclear power units, and plays a key role in ultra-high voltage and smart grid. Pressure fluctuations are the main reasons for the instability of the S-shaped region of pump–turbines, which seriously affects their lifespan and operation stability. To reveal the mechanism and propagation law of pressure fluctuations in the S-shaped region as well as numerical simulations at the turbine, the braking and the reverse pump operating conditions of a pump–turbine were carried out. Numerical results were validated using the performance experiments, and the generation mechanism and propagation law of pressure fluctuation were analyzed in detail. The analyses show that high-amplitude pressure fluctuations mainly occur in the braking and reverse pump operating conditions. Under the braking condition, a 0.49-fn low-frequency pressure fluctuation was captured, which is caused by the rotation of the backflow in the vanes. Under the reverse pump condition, a 0.19-fn low-frequency pressure fluctuation was confirmed, which is caused by the periodic rotation of the vortex between the vaneless space. This study has important guiding significance for practical engineering application.
A Real-Time Energy Management System Design for a Developed PV-Based Distributed Generator Considering the Grid Code Requirements in Turkey
Authors: Bayrak Gökay , Ertekin Davut , Haes Alhelou Hassan , Siano Pierluigi
Published: October 2021

Each country must determine the Grid Code conditions and apply these criteria to integrate distributed generation (DG) systems into the existing electricity grid and to ensure a stable power system. Thus, experimental studies are required to provide an effective, national, and specific Grid Code. In this study, the Turkish Grid Code’s electrical criteria were examined, and the application of these criteria was carried out on a developed PV-based DG. A real-time energy management system (RTEMS) was proposed in the study. Electrical parameters on the developed DG were monitored in real-time by considering IEEE 1547, IEEE 929–2000, and Turkey’s electrical criteria. A practical grid code study was firstly investigated in detail about the Turkish Grid Code by a developed real-time monitoring-control and protection system. The proposed RTEMS method in the study is implemented as an inverter-resident system; thus, it provides advantages over many energy management systems embedded in the inverter. The degradation in power quality and non-detection zone (NDZ) problems encountered in active and passive island mode detection methods developed embedded in the inverter are eliminated in the proposed method. With the RTEMS method, where under and over-voltage, under and over voltage frequency, and unintentional island mode events can be detected in real-time, both the existing grid-code requirements are met, and the existing power quality and NDZ problem is eliminated with the recommended inverter-independent RTEMS method.
Single-Cell Oils from Oleaginous Microorganisms as Green Bio-Lubricants: Studies on Their Tribological Performance
Authors: Patel Alok , Mu Liwen , Shi Yijun , Rova Ulrika , Christakopoulos Paul , Matsakas Leonidas
Published: October 2021

Biolubricants refer to eco-friendly, biodegradable, and non-toxic lubricants. Their applications are still limited compared to mineral oils; however, their sustainable credentials are making them increasingly attractive. Vegetable oils are frequently used for this purpose. However, vegetable oils have issues of low lipid productivity, dependence on climatic conditions, and need for agricultural land. Microbial oils represent a more sustainable alternative. To ensure their widespread applicability, the suitability of microbial oils from a physicochemical point of view needs to be determined first. In this study, oils obtained from various oleagenic microbes—such as microalgae, thraustochytrids, and yeasts—were characterized in terms of their fatty acid profile, viscosity, friction coefficient, wear, and thermal stability. Oleaginous microalgal strains (Auxenochlorella protothecoides and Chlorella sorokiniana), thraustochytrids strains (Aurantiochytrium limacinum SR21 and Aurantiochytrium sp. T66), and yeast strains (Rhodosporidium toruloides and Cryptococcus curvatus) synthesized 64.5%, 35.15%, 47.89%, 47.93%, 56.42%, and 52.66% of lipid content, respectively. Oils from oleaginous microalgae (A. protothecoides and C. sorokiniana) and yeasts (R. toruloides and C. curvatus) possess excellent physicochemical and tribological qualities due to high amount of monounsaturated fatty acids (oleic acid C18:1 content, 56.38%, 58.82%, 46.67%, 38.81%) than those from oleaginous thraustochytrids (A. limacinum SR21 and Aurantiochytrium sp. T66; 0.96%, 0.08%, respectively) supporting their use as renewable and biodegradable alternatives to traditional mineral oil-based lubricants. Oil obtained from microalgae showed a lower friction coefficient than oils obtained from yeasts and thraustochytrids.
Single-Phase Heat Transfer Characteristics of Water in an Industrial Plate and Shell Heat Exchanger under High-Temperature Conditions
Authors: Kim Kibong , Song Kang Sub , Lee Gilbong , Chang Kichang , Kim Yongchan
Published: October 2021

This study investigates the single-phase heat transfer, pressure drop, and temperature distribution of water in an industrial plate and shell heat exchanger (PSHE) under high-temperature conditions. In this experiment, the hot fluid flows downward on the plate side, while the cold fluid flows upward on the shell side. In the single-phase heat transfer experiment on water, the Nu is in the range of 7.85–15.2 with a Re from 1200 to 3200, which is substantially lower than that on the plate heat exchanger (PHE) studied previously. The decrease in the Nu is attributed to the reduced cross-sectional heat transfer area from the flow imbalance in the PSHE. As the Re increases, the pressure drop on the plate side increases more rapidly than that on the shell side because of the difference in the port pressure drop, flow direction, and flow position on the plate. When the Re is 2620, the pressure drops on the plate and shell sides are 52.5 kPa and 25.5 kPa, respectively, a difference of 51.4%. The temperature deviation on the circular plate increases as the Re decreases, especially between the edge and bottom of the plate because of uneven flow distribution on the plate.
Insights into Partial Slips and Temperature Jumps of a Nanofluid Flow over a Stretched or Shrinking Surface
Authors: He Ji-Huan , Abd Elazem Nader Y.
Published: October 2021

This paper elucidates the significance of partial slips and temperature jumps on the heat and mass transfer of a boundary layer nanofluid flowing through a stretched or shrinking surface. Considerable consideration is given to the dynamic properties of the nanofluid process, including Brownian motion and thermophoresis. A similarity transform is introduced to obtain a physical model of nonlinear ordinary differential equations, and the Chebyshev method of collocation is used to numerically analyze the influences of parameters of physical flow such as slip, temperature jump, Brownian motion, thermophoresis, suction (or injection) parameters, and Lewis and Prandtl numbers. The numerical results for temperature and concentration profiles, and heat and mass transfer rates, are graphically represented, and insights into the effects of slips and temperature jumps are revealed. In the case of a stretched sheet, the slip parameter enhances the temperature field and increases the thermal boundary layer thickness as well as the concentration function’s boundary layer thickness. When the slip parameter is raised in the case of the shrinking sheet, the dual solutions for temperature and concentration functions are reduced. For the first solution, both the temperature and concentration functions drop as the slip parameter increases, but for the second solution, both the temperature and concentration functions rise as the slip parameter increases. The discoveries have applications in a number of disciplines, including heat transfer in a solar energy collector. Glass blowing, annealing, and copper wire thinning are just a few of the technical and oilfield applications for the current problem. In high-temperature industrial applications, radiation heat transfer research is critical.
FAIR Metadata Standards for Low Carbon Energy Research—A Review of Practices and How to Advance
Authors: Wierling August , Schwanitz Valeria Jana , Altinci Sebnem , Bałazińska Maria , Barber Michael J. , Biresselioglu Mehmet Efe , Burger-Scheidlin Christopher , Celino Massimo , Demir Muhittin Hakan , Dennis Richard , Dintzner Nicolas , el Gammal Adel , Fernández-Peruchena Carlos M. , Gilcrease Winston , Gładysz Paweł , Hoyer-Klick Carsten , Joshi Kevin , Kruczek Mariusz , Lacroix David , Markowska Małgorzata , Mayo-García Rafael , Morrison Robbie , Paier Manfred , Peronato Giuseppe , Ramakrishnan Mahendranath , Reid Janeita , Sciullo Alessandro , Solak Berfu , Suna Demet , Süß Wolfgang , Unger Astrid , Fernandez Vanoni Maria Luisa , Vasiljevic Nikola
Published: October 2021

The principles of Findability, Accessibility, Interoperability, and Reusability (FAIR) have been put forward to guide optimal sharing of data. The potential for industrial and social innovation is vast. Domain-specific metadata standards are crucial in this context, but are widely missing in the energy sector. This report provides a collaborative response from the low carbon energy research community for addressing the necessity of advancing FAIR metadata standards. We review and test existing metadata practices in the domain based on a series of community workshops. We reflect the perspectives of energy data stakeholders. The outcome is reported in terms of challenges and elicits recommendations for advancing FAIR metadata standards in the energy domain across a broad spectrum of stakeholders.
Grasped Object Weight Compensation in Reference to Impedance Controlled Robots
Authors: Winiarski Tomasz , Jarocki Szymon , Seredyński Dawid
Published: October 2021

This paper addresses the problem of grasped object weight compensation in the one-handed manipulation of impedance controlled robots. In an exemplary identification procedure, the weight of an object and its centre of mass together with gripper kinematic configuration are identified. The procedure is based on the measurements from a 6-axis force/torque sensor mounted near the gripper. The proposed method reduces trajectory tracking errors coming from the model imprecision without compromising the main advantages of impedance control. The whole approach is applied according to the embodied agent paradigm and verified on the two-arm service robot both in simulation and on hardware. Due to the general description that follows system engineering standards, the method can be easily modified or applied to similar systems.
Twin-Delayed Deep Deterministic Policy Gradient for Low-Frequency Oscillation Damping Control
Authors: Cui Qiushi , Kim Gyoungjae , Weng Yang
Published: October 2021

Due to the large scale of power systems, latency uncertainty in communications can cause severe problems in wide-area measurement systems. To resolve this issue, a significant amount of past work focuses on using emerging technology, including machine learning methods such as Q-learning, for addressing latency issues in modern controls. Although the method can deal with the stochastic characteristics of communication latency, the Q-values can be overestimated in Q-learning methods, leading to high bias. To address the overestimation bias issue, we redesign the learning structure of the deep deterministic policy gradient (DDPG). Then we develop a damping control twin-delayed deep deterministic policy gradient method to handle the damping control issue under unknown latency in the power network. The purpose is to address the damping control issue under unknown latency in the power network. This paper will create a novel reward algorithm, taking into account the machine speed deviation, the episode termination prevention, and the feedback from action space. In this way, the system optimally damps down frequency oscillations while maintaining the system’s stability and reliable operation within defined limits. The simulation results verify the proposed algorithm in various perspectives, including the latency sensitivity analysis under high renewable energy penetration and the comparison with conventional and machine learning control algorithms. The proposed method shows a fast learning curve and good control performance under varying communication latency.
Distribution Network Reconfiguration Applied to Multiple Faulty Branches Based on Spanning Tree and Genetic Algorithms
Authors: Guamán Alex , Valenzuela Alex
Published: October 2021

The distribution network is the most exposed part of the electrical power system relative to different abnormal events; therefore, it reports the highest occurrence rates in terms of electrical and mechanical failures. The present project describes a strategy for restoring faulty areas after the occurrence of an abnormal event causing an outage; consequently, the proposed algorithm is not only focused on the maximization of the connected loads but also deals with the minimization of the switching operations by considering technical operational constraints. The remarked study has two stages: The first one finds an initial set of tie-line candidates using the spanning tree technique, while the second stage applies a genetic algorithm to determine the optimal solution considering all the constraints. Three cases studies have been used to test the proposed algorithm, then the simulation and results of IEEE 13, 37 and 94 node feeders depict the effectiveness of the restoration strategy.
Seismic Response Analysis of Tunnel through Fault Considering Dynamic Interaction between Rock Mass and Fault
Authors: Liu Guoqing , Zhang Yanhong , Ren Junqing , Xiao Ming
Published: October 2021

In order to explore the influences of fault dislocations on tunnel stability under seismic action, a nonlinear dynamic simulation method for the rock–fault contact system is proposed. First, considering the deterioration effect of seismic action on the ultimate bearing load of the contact interface between rock mass and fault, a mathematical model is established reflecting the seismic deterioration laws of the contact interface. Then, based on the traditional point-to-point contact type in a geometric mesh, a point-to-surface contact type is also considered, and an improved dynamic contact force method is established, which considers the large sliding characteristics of the contact interface. According to the proposed method, a dynamic finite element calculation for the flow of the rock–fault contact system is designed, and the accuracy of the method is verified by taking a sliding elastic block as an example. Finally, a three-dimensional (3D) calculation model for a deep tunnel through a normal fault is built, and the nonlinear seismic damage characteristics of the tunnel under horizontal seismic action are studied. The results indicate that the relative dislocation between the rock mass and the fault is the main factor that results in lining damage and destruction. The seismic calculation results for the tunnel considering the dynamic interaction between the rock mass and the fault can more objectively reflect the seismic response characteristics of practical engineering. In addition, the influences of different fault thicknesses and dip angles on the seismic response of the tunnel are discussed. This work provides effective technical support for seismic fortification in a tunnel through fault.
Increasing the Efficiency of Sealing the Borehole in Terms of Spacer Pumping Time
Authors: Kremieniewski Marcin , Kędzierski Miłosz , Błaż Sławomir
Published: October 2021

The tightness of a borehole is essential for its long-term durability. For this purpose, the column of the pipe is sealed with cement slurry. After contacting the slurry, mud in the borehole is removed. However, the slurry does not effectively remove the remaining drilling mud. Therefore, the annular space is cleaned with a wash. Effectively cleaning the borehole presents quite a problem, as many variables that affect the stability of the borehole need to be considered. The time of contact between the borehole and the wash is very important. On the one hand, insufficient contact time does not guarantee proper removal of the mud. On the other hand, a long contact time may destroy the wall of the borehole. To address these problems, studies were carried out to assess the effect of the wash contact time on annular space cleaning. When determining the time of washing, a compromise between effective cleaning and the stability of the borehole wall is required. In the research presented in this publication, the simplest wash was used, i.e., water. This choice was based on the objective of observing the influence of the wash time on cleaning, i.e., the preparation of the borehole for cementing. By using water, the physicochemical action of surfactants can be ignored. In order to capture changes in cleaning due to differences in contact time, a control test was performed using a pure sandstone core without mud. The effect of the wash contact time on the cleaning of the annular space was investigated by determining the adhesion of the cement sheath to the rock core. First, mud was formed on the core, and then it was removed. By comparing the obtained adhesion to the reference sample, the effectiveness of the deposit removal was determined. On the basis of this research, the optimal wash contact time was determined.
Prediction of Extreme Conditional Quantiles of Electricity Demand: An Application Using South African Data
Authors: Maswanganyi Norman , Sigauke Caston , Ranganai Edmore
Published: October 2021

It is important to predict extreme electricity demand in power utilities as the uncertainties in the future of electricity demand distribution have to be taken into consideration to achieve the desired goals. The study focused on the prediction of extremely high conditional quantiles (between 0.95 and 0.9999) and extremely low quantiles (between 0.001 and 0.05) of electricity demand using South African data. The paper discusses a comparative analysis of the additive quantile regression model with an extremal mixture model and a nonlinear quantile regression model. The estimated quantiles at each level were then combined using the median approach. The comparisons were carried out using daily peak electricity demand data ranging from January 1997 to May 2014. Proper scoring rules were used to compare the three models, and the model with the smallest score was preferred. The results could be useful to system operators including decision-makers in power utility companies by giving insights and guidance for future electricity demand patterns. The prediction of extremely high quantiles of daily peak electricity demand could help system operators know the possible largest demand that will enable them to supply adequate electricity to consumers and shift demand to off-peak periods. The prediction of extreme conditional quantiles of daily peak electricity demand in the context of South Africa using additive quantile regression, nonlinear quantile regression, and extremal mixture models has not been performed previously to the best of our knowledge.