bluuebunny/crossref_metadata_2025_split huggingface dataset:
A comparative study of marginal loss pricing algorithms in electricity markets
Authors: Yang Jiajia , Dong Zhao Yang , Wen Fushuan 
Published: December 2020

AbstractDue to the development of new technologies, change of generation mix and appearance of newly formed energy supply hubs, there is a large year‐on‐year change in the marginal loss factors in power systems. Since any change of marginal loss factors could have significant impacts on payment of loads and profitability of generators, it is necessary to carry out a comparative study on the loss factor‐based locational marginal pricing methods. Considering that a systematic comparison of various locational marginal pricing methods has not been reported in existing publications, this work presents a comparative study of the loss factor‐based locational marginal pricing methods that are widely adopted in electricity markets. Advantages and disadvantages of each locational marginal pricing method are explored in detail, and could serve as references in selecting appropriate locational marginal pricing methods in practice. The selected five locational marginal pricing models are tested in two standard power systems, that is, the IEEE 5‐bus and 39‐bus systems. Then, through numerical experiments and detailed analysis, key findings about the reference point dependency of loss factors, accuracy of loss estimation, load payment, generation income, and market settlement surplus are summarised and elaborated. It is found that marginal loss factors‐based locational marginal pricing methods tend to produce a higher market settlement surplus and can lead to a lower generation income than other locational marginal pricing methods.
Distributed generation hosting capacity in electric distribution network in the presence of correlated uncertainties
Authors: Solat Sajjad , Aminifar Farrokh , Shayanfar Heidarali 
Published: December 2020

AbstractHigh penetration of renewable distributed generations is one of the most current challenges of electric distribution networks due to resources uncertainties, and hosting capacity limitation of the networks. The challenges may be more critical when uncertainties are highly correlated. The effect of correlated uncertainties of wind speed and load on the distributed generation hosting capacity of distribution networks is evaluated. A combination of point estimation method, and inverse Nataf transformation is proposed for correlated uncertainties modelling. The efficiency of some ANM schemes on the hosting capacity improvement is also studied in the presence of correlated uncertainties. To do so, an optimisation framework with the objective of maximising the installed capacity of distributed generation subject to network operational constraints such as voltage deviation is proposed. The proposed optimisation problem is formulated in a mixed‐integer quadratically constrained program form, and is solved via CPLEX solver. The proposed method is implemented on the 33‐bus standard test system. The results demonstrate the significant effect of the correlation between uncertainties on the distributed generation hosting capacity of network.
Ageing characteristics and lifetime model of oil–paper insulation for oil‐immersed paper condenser bushing
Authors: Gao Sihang , Yang Lijun , Ke Tingjing 
Published: December 2020

AbstractThis study extensively investigated the ageing characteristics and lifetime model of oil–paper insulation for oil‐immersed paper condenser bushing. The accelerated thermal and electrothermal ageing experiments of oil‐immersed paper condenser bushing were conducted respectively. The properties of oil–paper insulation during the ageing process were investigated. Results showed that descending speed of degree of polymerization of the innermost and the outermost layer paper was higher than that of middle layer paper, the difference in water content on different paper layers caused varying deterioration speeds. The aluminium foil contributed to a surge in aluminium dissolution in oil, further accelerating the ageing of insulation. Based on the obtained degree of polymerization data under thermal ageing at 90°C, 100°C and 130°C, the lifetime model of oil–paper insulation for condenser bushing model was established. In addition, the surface breakdown of the scale model of bushing occurred after 133 days ageing, the properties of bushing decreased gradually during the ageing process and sharply after the breakdown. Degree of polymerization deviation of different paper layers in bushing between calculated value according to the above lifetime model and actual value of bushing after the breakdown was less than 6%, further verifying the validity of lifetime model.
Equipotential shielding voltage sensor for contact measurement of transient voltage in EHV/UHV power grids
Authors: Zheng Jianchao , Li Bo , Zha Kunpeng , Guo Ningming , Wang Liming 
Published: December 2020

AbstractIn this study, an equipotential shielding voltage sensor is proposed to achieve contact measurement of transient voltage in extra‐high voltage (EHV)/ultra‐high voltage (UHV) power grids. Two design versions of the voltage sensor for engineering application are described. One version of the sensor is designed as a miniaturized sensor for non‐disturbing measurement of potential distribution along power electronic equipment under transient voltage. The other version is designed for online measurement and monitoring in alternating current EHV/UHV power grids. Based on the design parameters, the performance of the sensor is evaluated, including stability of measurement, shielding effect against the interference from adjacent objects and frequency bandwidth. In order to verify the performance of this sensor, an experimental comparison between this sensor and a standard capacitive voltage divider used in high voltage laboratory was carried out and the results of comparison are presented. The results show that the difference of measured peak voltage between the two devices is no more than ±5%, and the difference of measured time parameters between the two devices is no more than ±15%.
3D particle‐in‐cell simulation of positive streamer initiation in highly pressurized gaseous, liquid and supercritical CO2 with field ionization
Authors: Abbas Muhammad Farasat , Yuan Xu‐Chu , Li Han‐Wei , Xue Jian‐Yi , Sun An‐Bang , Zhang Guan‐Jun 
Published: December 2020

AbstractA 3D particle‐in‐cell/Monte Carlo collision model is used to investigate the streamer discharge inception in CO2 at elevated pressures including gaseous, liquid and supercritical phases. Generation of free electrons is a prerequisite for initiation and development of positive streamers. Field ionization from impurity molecules of low density and low ionization energy is assumed as the source of primary ionization in the model. The field dependent generation rate of electrons is calculated by Zener's model. Tree‐like streamer with filamentary shape presents at the needle tip and propagates towards the plane electrode in all three phases of CO2, with differing in length and propagation speed. Furthermore, the influence of different parameters such as applied voltage, electrode tip size, and ionizable density and ionization potential of impurity molecules on the evolution of streamer discharge in supercritical CO2 are investigated. Simulation results obtained from the 3D model agree well with experimental observations in the literature, which show that field ionization might be one of possible ionization sources in pressurized CO2 in the presence of high electric field.
In‐situ observation of electrical tree evolution in epoxy dielectrics with internal cracks
Authors: Wu Zehua , Tian Huidong , Zhu Sijia , Li He , Wang Qingyu , Xie Zongliang , Liu Peng , Peng Zongren 
Published: December 2020

AbstractGas‐filled internal crack might appear in thermoset materials like epoxy resin during the equipment manufacturing, which would become a vulnerable local region to initiate the electrical tree, thus prone to cause insulation failure. The withstand voltage test was carried on epoxy samples with artificial cracks based on a rod‐plane electrode arrangement. Simultaneously, surface state variation and tree evolution with crack were observed by an optical microscope in conjunction with a charge‐coupled device camera. The changes in morphology and chemical status of the crack surface were characterized by scanning electron microscopy, laser Raman spectrometer and energy dispersive spectrometer, respectively. It was found that the erosion and tree started from the borderline of crack under a relatively low electric field strength; however, the area near the electrode had relatively little damage. The breaking of epoxy molecular chains coarsens the crack surface and further forms deep channels on a micro‐level, which is the forerunner of the electrical tree inception. Based on these, the initiation mechanisms of the crack‐induced electrical tree and the reasons for the erosion near the borderline have been revealed. This study provides a train thought for the polymer degradation opening up into the initial tree channel during tree evolution processes.
ShuffleNet‐based comprehensive diagnosis for insulation and mechanical faults of power equipment
Authors: Wang Yanxin , Yan Jing , Sun Qifeng , Zhao Yiming , Liu Tingliang 
Published: December 2020

AbstractDespite the complicated fault mechanism of power equipment, with the increasing promotion and development of the Ubiquitous Power Internet of Things (UPIoT), the fault information of power equipment can be instantly saved, which makes possible intelligent diagnosis via fault samples. This study proposes a new method to implement comprehensive intelligent diagnosis by adopting the ShuffleNet lightweight convolution neural network (SLCNN). Considering the requirements of the UPIoT intelligent terminal, this study constructs six models, which are measured in terms of recognition accuracy, model storage, and calculation cost when applied to insulation and mechanical datasets. Compared with the existing models, the SLCNN outperforms them significantly in terms of recognition accuracy, with an accuracy of 95.77% and 99.9% in insulation and mechanical fault diagnoses, respectively. The SLCNN also demonstrates obvious advantages in other performance indicators, all of which contribute to its use in the accurate and reliable fault diagnosis of power equipment in the UPIoT context. Furthermore, through comparing feature maps, it is discovered that the aliasing degree and boundary of insulation defects are not as obvious as those of mechanical faults, which means that insulation fault diagnosis is much more difficult than mechanical fault diagnosis.
Completely blind image quality assessment via contourlet energy statistics
Authors: Li Chaofeng , Guan Tuxin , Zheng Yuhui , Jin Bo , Wu Xiaojun , Bovik Alan 
Published: December 2020

AbstractAn aim of completely blind image quality assessment (BIQA) is to develop algorithms which can grade image quality without any prior knowledge of the images. Here, a new contourlet energy statistics based completely on blind opinion‐unaware BIQA (OU‐BIQA) method is proposed, which can predict the perceptual severity of a range of image distortion types without requiring any prior knowledge. According to the energy distribution of the contourlet sub‐bands of natural images in log‐domain, the lower‐scale sub‐band energy can be predicted by the corresponding higher‐scale sub‐band energies of distorted images. A quality model is then constructed by quantifying the difference between predicted energy and realistic energy. Meanwhile, an effective method for adjusting and compensating an undesired distortion is integrated into the quality model. Experimental results show that the proposed new method outperforms state‐of‐the‐art OU‐BIQA models on relevant portions of TID2013 database, and is competitive on the LIVE IQA database. Moreover, the proposed model is very fast, suggesting a real‐time solution to high‐performance BIQA.
Digital image steganalysis: A survey on paradigm shift from machine learning to deep learning based techniques
Authors: Selvaraj Arivazhagan , Ezhilarasan Amrutha , Wellington Sylvia Lilly Jebarani , Sam Ananthi Roy 
Published: December 2020

AbstractSteganography, a branch of data hiding techniques aims to hide confidential information within any digital media by obscuring the existence of hidden information. On the contrary, steganalysis aims to detect steganography. With the advent of powerful steganographic algorithms, the process of cracking them became very challenging. Traditional steganalysis following machine learning principle employs a two‐step process, with first process extracting highly sophisticated features capable of discriminating hidden message from original data and second process classifying the input as innocent or guilty. In recent years, deep learning which has its roots in artificial neural networks emerged as a brilliant alternative for many computer vision tasks. A review of recent research works in deep learning based digital image steganalysis is presented here. The paradigm shift from machine learning approaches to employing more promising deep learning architectures, observed with the current research community and hence in literature has been presented here in chronological order. Deep learning can unify the two‐step process into a single process by giving the ability for machine to learn end‐to‐end by itself. The use of Convolutional Neural Networks to perform steganalysis in spatial or transform or combination of both domains has effectively lowered the detection error rates.
Inhomogeneity in the early Galactic chemical enrichment exposed by beryllium abundances in extremely metal-poor stars
Authors: Smiljanic R. , Zych M. G. , Pasquini L. 
Published: December 2020

Context. Abundances of beryllium in metal-poor stars scale linearly with metallicity down to [Fe/H] ∼ −3.0. In the stars where Be has been detected at this extremely metal-poor regime, an increased abundance scatter has been previously reported in the literature. This scatter could indicate a flattening of the relation between Be abundances and metallicity.
Aims. Our aim is to perform a new investigation of Be abundances in extremely metal-poor stars and try to clarify whether a Be abundance plateau exists. We revisited the Be abundances in a sample of nine dwarfs with metallicities close to [Fe/H] ∼ −3.0. Additionally, we analysed the Be lines in the spectra of stars BPS BS 16968-0061 and CD-33 1173 for the first time.
Methods. We took advantage of Gaia DR2 parallaxes to refine values of the surface gravity of the stars. Updated values of surface gravity can have a significant impact on the determination of Be abundances. The other atmospheric parameters were computed using photometric and spectroscopic data. Abundances of Be were determined using spectrum synthesis and model atmospheres.
Results. Some of the stars indeed suggest a flattening. Over about a 0.5 dex range in metallicity, between [Fe/H] ∼ −2.70 and −3.26, the Be abundances stay mostly constant at about log(Be/H) ∼ −13.2 dex. Nevertheless, for several stars, we could only place upper limits that are below that level. Most of the sample stars are consistent with having been formed at the progenitor of the so-called Gaia-Enceladus merger. Two out of the three stars likely formed in-situ are the ones that deviate the most from the linear relation.
Conclusions. The mixed origin of these extremely metal-poor stars offers a clue to understanding the flattening. We suggest that our observations can be naturally understood as a consequence of the inhomogeneous star forming conditions in the early Galaxy. Without efficient mixing, the early interstellar medium would be characterised by a large scatter in Fe abundances at a given moment. Beryllium, on the other hand, because of its origins in cosmic-ray spallation, would have more homogeneous abundances (in a Galaxy-wide sense). We therefore suggest that the observed flattening of the Be-versus-metallicity relation reflects a stronger scatter in the Galactic Fe abundances at a given age.
Martha Ulrich und Toni Schmidt-Kraepelin
Authors: Prokop Jana , Karenberg Axel 
Published: December 2020

ZUSAMMENFASSUNG
Gegenstand und Ziel Mithilfe von 2 exemplarischen Biografien sollen die berufliche Laufbahn und Lebensumstände von Nervenärztinnen zwischen 1900 und 1950 beleuchtet werden. Dabei stehen Hochschulzugang, Medizinstudium, Forschung sowie Tätigkeit in Klinik und Praxis vom Kaiserreich bis zur Bundesrepublik im Mittelpunkt.
Material und Methoden Schlüssige Kriterien führten zu einer klaren Definition des Begriffs „Pionierin“. Die Rekonstruktion der Lebensläufe gelang durch die Analyse von umfangreichem Archivmaterial und Originalpublikationen. Mittels Auswertung relevanter Sekundärliteratur konnten die bioergografischen Vignetten in den Kontext der Zeit eingeordnet werden.
Ergebnisse Beide Nervenärztinnen begannen ihr Studium in den 1900er-Jahren, traten zur Weiterbildung in Universitäts- kliniken ein und waren viele Jahre als „Specialisten“ bzw.niedergelassene Fachärztinnen gemäß der Bremer Richtlinie von 1924 tätig. Beide publizierten wissenschaftliche Arbeiten, ohne aufgrund zeitgenössischer Hürden die Chance einer akademischen Karriere zu haben. Während Ulrich unverheiratet und kinderlos blieb, lebte Schmidt-Kraepelin die gesellschaftlich neue Doppelrolle von Hausfrau/Mutter und berufstätiger Medizinerin. Letztere war zudem als Assistenzärztin einer „Sammelanstalt“ in die NS-„Euthanasie“ involviert und wurde nach 1945 mit Vorwürfen konfrontiert.
Schlussfolgerungen Anschaulich dargestellte Lebensgeschichten bilden einen hervorragenden Zugang, um historische Sachverhalte wie Anfänge des Frauenstudiums, berufliche (Nicht-)Optionen von Nervenärztinnen und deren moralische Herausforderungen in der ersten Hälfte des 20. Jahrhunderts nachvollziehbar zu machen. Weitere Fallstudien sind wünschenswert, um aktuelle Kontroversen in den Fächern Neurologie/Psychiatrie um eine historische Tiefendimension zu erweitern.
Utility and Safety of Repeat Transurethral Resection of Bladder Tumor Performed at a Tertiary Center
Authors: Raja Anand , Malik Kanuj , Arunandhichelvan Arulmolichelvan , Kathiresan N. , Ravishankar L. S. 
Published: December 2020

Abstract
Introduction Repeat transurethral resection of bladder tumor (ReTURBT) has become an integral part of the management of superficial bladder cancers at various urological centers around the world. Early detection of residual disease, leading to upstaging in some cases, leads to decrease in recurrence rates. Our study aimed to analyze the impact of ReTURBT in detecting residual tumor and tumor recurrences, hence validating the benefits of procedure as a routine.
Materials and Methods A total of 152 patients with superficial bladder cancer who were treated at Cancer Institute (WIA) between January 2005 and December 2013 were analyzed and followed up for 3 years.
Results Of the 152 cases who underwent ReTURBT, 47 patients had residue in the final histopathology of the resected specimen (31%). The overall rate of upstaging to muscle-invasive disease following ReTURBT was 3.3%. The mean follow-up period was 47.13 months, during which 25 (17%) out of 147 patients who underwent ReTURBT had disease recurrence. There was no additional morbidity due to ReTURBT as compared with the primary procedure.
Conclusion ReTURBT is an effective procedure in treating recurrent tumors also as long as they remain superficial. The procedure when performed with utmost care in experienced hands remains a very safe procedure to be followed as a routine and standard.
On the market for “Lemons”: quality provision in markets with asymmetric information
Authors: Giannakas Konstantinos , Fulton Murray 
Published: December 2020

AbstractAkerlof’s “Lemons” paper provides a seminal economic result suggesting that, in markets with asymmetric information where product quality is unobservable by consumers prior to purchase and use, the introduction of a low-quality product will drive its higher quality counterpart(s) out of the market. In this paper we identify some empirically relevant cases/conditions under which the introduction of a low-quality product does not drive its higher quality substitutes out of the market but, instead, ends-up coexisting with them.
Tissue flossing of the thigh increases isometric strength acutely but has no effects on flexibility or jump height
Authors: Konrad Andreas , Bernsteiner Daniel , Budini Francesco , Reiner Marina Maren , Glashüttner Christoph , Berger Christian , Tilp Markus 
Published: December 2020

AbstractThe purpose of this study was to investigate the effects of a single floss band treatment of the thigh on hip and knee range of motion (ROM), knee extensor passive resistive torque (PRT), knee extensor maximum voluntary contraction (MVC) torque, and countermovement jump (CMJ) height.Sixteen healthy male volunteers were tested before and after both the flossing treatment and the control condition, in random order. For the flossing treatment, the floss band was wound around both thighs for 120 s, and the subject was then asked to perform 20 squats. During the control treatment, only the 20 squats were performed. Before and after the treatments, knee and hip ROM were assessed using a Thomas test with 3D motion caption. The PRT and MVC of the knee extensors were measured with a dynamometer, and the electromyographic (EMG) signal was collected from the vastus lateralis. CMJs were performed on a force plate.Compared to the control condition, the flossing treatment showed a positive effect on the MVC of the knee extensors (P = 0.01); however, no effects on hip ROM (P = 0.58), knee ROM (P = 0.37), CMJ height (P = 0.75), or PRT (P = 0.22) were observed. Correlation analyses revealed that the increase in MVC was not significantly related to changes in the tension of the muscle‐tendon unit (rP = −0.13; P = 0.64) or vastus lateralis EMG (rS = 0.44; P = 0.10). Since the increase in MVC cannot be explained by changes of the mechanical (PRT) or neuromuscular (EMG) properties, we speculate that an enhancement of growth hormone and norepinephrine levels following the compression release is instead responsible for the increase in MVC.
Unique determination for an inverse problem from the vortex dynamics
Authors: Lai Ru-Yu , Zhou Hanming 
Published: December 2020

Abstract
We consider the problem of reconstructing a background potential from the dynamical behavior of vortex dipole. We prove that under suitable conditions, one can uniquely reconstruct a real-analytic potential by measuring the entrance and exit positions as well as travel times between boundary points. In particular, the work removes the flatness assumption on the potential from the earlier result. A key step of our method is a constructional procedure of recovering the boundary jet of the potential.