bluuebunny/crossref_metadata_2025 huggingface dataset:
Day‐ahead and intra‐day wind power forecasting based on feedback error correction
Authors: Gupta Akshita , Kumar Arun , Boopathi Kadhirvel
Published: May 2021

The major hindrance in the development of large‐scale grid integration of wind energy into the power system is the production of intermittent and variable power. A largescale integration requires a forecasting mechanism to support the power system operators while operating the grids. This study forecasts the day‐ahead and intra‐day wind power using the wavelet decomposition, followed by the autoregressive integrated moving average. The forecasting has been attempted on two datasets, actual and error wind power. The forecasting using the wavelet decomposition employs the discrete wavelets consisting of 16 wavelets, grouped into 5 families. The optimum length of the past data used for the model formulation has also been examined for the various scenarios. The forecasting results have been compared based on various performance metrics. The results of the forecasted values have been compared with the reference ARIMA model to see the effectiveness of the proposed wavelet‐ARIMA model. The results indicate that the feedback mechanism used in the error dataset have improved the forecasting efficiency over the use of actual data in both the day‐ahead and intra‐day forecasting. Also, it has been observed that some of the wavelet families outperformed the other families in terms of accuracy and speed.
MOLsphere and pulsations of the Galactic Center’s red supergiant GCIRS 7 from VLTI/GRAVITY
Authors:   GRAVITY Collaboration, Rodríguez-Coira G. , Paumard T. , Perrin G. , Vincent F. , Abuter R. , Amorim A. , Bauböck M. , Berger J. P. , Bonnet H. , Brandner W. , Clénet Y. , de Zeeuw P. T. , Dexter J. , Drescher A. , Eckart A. , Eisenhauer F. , Förster Schreiber N. M. , Gao F. , Garcia P. , Gendron E. , Genzel R. , Gillessen S. , Habibi M. , Haubois X. , Henning T. , Hippler S. , Horrobin M. , Jimenez-Rosales A. , Jochum L. , Jocou L. , Kaufer A. , Kervella P. , Lacour S. , Lapeyrère V. , Le Bouquin J. B. , Léna P. , Nowak M. , Ott T. , Perraut K. , Pfuhl O. , Sanchez-Bermudez J. , Shangguan J. , Scheithauer S. , Stadler J. , Straub O. , Straubmeier C. , Sturm E. , Tacconi L. J. , Shimizu T. , von Fellenberg S. , Waisberg I. , Widmann F. , Wieprecht E. , Wiezorrek E. , Woillez J. , Yazici S. , Zins G.
Published: May 2021

Context. GCIRS 7, the brightest star in the Galactic central parsec, formed 6 ± 2 Myr ago together with dozens of massive stars in a disk orbiting the central black-hole. It has been argued that GCIRS 7 is a pulsating body, on the basis of photometric variability.

Aims. Our goal is to confirm photospheric pulsations based on interferometric size measurements to better understand how the mass loss from these massive stars enriches the local interstellar medium.

Methods. We present the first medium-resolution (R = 500), K-band spectro-interferometric observations of GCIRS 7, using the GRAVITY instrument with the four auxiliary telescopes of the ESO VLTI. We looked for variations using two epochs, namely 2017 and 2019.

Results. We find GCIRS 7 to be moderately resolved with a uniform-disk photospheric diameter of θUD* = 1.55 ± 0.03 mas (RUD* = 1368 ± 26 R⊙) in the K-band continuum. The narrow-band uniform-disk diameter increases above 2.3 μm, with a clear correlation with the CO band heads in the spectrum. This correlation is aptly modeled by a hot (TL = 2368 ± 37 K), geometrically thin molecular shell with a diameter of θL = 1.74 ± 0.03 mas, as measured in 2017. The shell diameter increased (θL = 1.89 ± 0.03 mas), while its temperature decreased (TL = 2140 ± 42 K) in 2019. In contrast, the photospheric diameter θUD* and the extinction up to the photosphere of GCIRS 7 (AKS = 3.18 ± 0.16) have the same value within uncertainties at the two epochs.

Conclusions. In the context of previous interferometric and photo-spectrometric measurements, the GRAVITY data allow for an interpretation in terms of photospheric pulsations. The photospheric diameter measured in 2017 and 2019 is significantly larger than previously reported using the PIONIER instrument (θ* = 1.076 ± 0.093 mas in 2013 in the H band). The parameters of the photosphere and molecular shell of GCIRS 7 are comparable to those of other red supergiants that have previously been studied using interferometry. The extinction we measured here is lower than previous estimates in the direction of GCIRS 7 but typical for the central parsec region.
Thermal evolution of Uranus and Neptune
Authors: Scheibe Ludwig , Nettelmann Nadine , Redmer Ronald
Published: May 2021

Thermal evolution models suggest that the luminosities of both Uranus and Neptune are inconsistent with the classical assumption of an adiabatic interior. Such models commonly predict Uranus to be brighter and, recently, Neptune to be fainter than observed. In this work, we investigate the influence of a thermally conductive boundary layer on the evolution of Uranus- and Neptune-like planets. This thermal boundary layer (TBL) is assumed to be located deep in the planet and be caused by a steep compositional gradient between a H–He-dominated outer envelope and an ice-rich inner envelope. We investigate the effect of TBL thickness, thermal conductivity, and the time of TBL formation on the planet’s cooling behaviour. The calculations were performed with our recently developed tool based on the Henyey method for stellar evolution. We make use of state-of-the-art equations of state for hydrogen, helium, and water, as well as of thermal conductivity data for water calculated via ab initio methods. We find that even a thin conductive layer of a few kilometres has a significant influence on the planetary cooling. In our models, Uranus’ measured luminosity can only be reproduced if the planet has been near equilibrium with the solar incident flux for an extended period of time. For Neptune, we find a range of solutions with a near constant effective temperature at layer thicknesses of 15 km or larger, similar to Uranus. In addition, we find solutions for thin TBLs of a few km and strongly enhanced thermal conductivity. A ~ 1 Gyr later onset of the TBL reduces the present ΔTby an order of magnitude to only several 100 K. Our models suggest that a TBL can significantly influence the present planetary luminosity in both directions, making it appear either brighter or fainter than the adiabatic case.
Outer invariance entropy for discrete-time linear systems on Lie groups
Authors: Colonius Fritz , Cossich João A.N. , Santana Alexandre J.
Published: May 2021

We introduce discrete-time linear control systems on connected Lie groups and present an upper bound for the outer invariance entropy of admissible pairs (K, Q). If the stable subgroup of the uncontrolled system is closed and K has positive measure for a left invariant Haar measure, the upper bound coincides with the outer invariance entropy.
Screening refrigerant for a new enhanced ejector heat exchanger used in district heating system based on industrial waste heat
Authors: Sun Fangtian , Hao Baoru , Chen Xu
Published: May 2021

Performance of the new enhanced ejector heat exchanger is the key to improving performance of the district heating system based on industrial waste heat, and it is significantly affected by thermo-physical property of refrigerant. In this paper, characteristics of the new enhanced ejector heat exchanger are considered, and a new principle for screening refrigerant is proposed. Eleven kinds of refrigerants are firstly selected as candidates, and then they are evaluated from the perspective of property and thermodynamic performance of the new enhanced ejector heat exchanger. The results show that refrigerant property has a greater influence on thermodynamic performance of the new enhanced ejector heat exchanger. Under the condition of low temperature space heating, R152a and R1234yf are favorable choices for the new enhanced ejector heat exchanger. While under conditions of other temperature space heating, R245fa and R600 are better choices for the new enhanced ejector heat exchanger.
A study on trade frictions of China’s new energy auto in international marketing and the countermeasures
Authors: Zhao Lingzhi
Published: May 2021

Manifestations of China’s new energy auto trade frictions are analyzed in this paper. The influence and causes of China’s new energy auto trade frictions are explored. It included individualism versus collectivism, long-term orientation versus short-term orientation, masculinity versus femininity. Finally, the countermeasures of relieve auto trade frictions have been provided, such as strengthening international exchanges, cultivating international management talents, and enhancing the ability of managing the trade frictions in international marketing. The development of China’s new energy vehicles to seek technological innovation in key fields like new energy vehicle batteries can be push forward. For Chinese auto companies, the investment should be reinforced and their independent innovation capabilities should be enhanced. Some suggestions for the sound development of China’s new energy auto trade in the future have been provided in order to build brand-new harmonious international atmosphere,
Intelligent power equipment identification model based on grid topology analysis
Authors: Su Shi , Yang Jun , Zhang Chunhui , Ma Xiaowei , Luan Siping
Published: May 2021

With the continuous development of the power grid, power equipment becomes more complex and diverse, which has increased the workload of power maintenance personnel. This paper proposes a method of intelligent identification of distribution network equipment to reduce the power maintenance personnel's workload. The model needs device photos, GPS coordinates, and device topology information of the entire power grid to infer the possible situation of the current device. The model is mainly divided into two parts: target recognition and equipment prediction. In target recognition, we propose a Self-attention target detection network (SA-TDN) that combines Faster-RCNN and Attention mechanism. In equipment prediction part, we use KD-Tree to analyse the grid topology to predict the real identification of the device. We compared this model with other convolutional neural networks (CNN) classification models. The results show that our model is ahead of current models in prediction accuracy.
An abnormal traffic detection method in smart substations based on coupling field extraction and DBSCAN
Authors: Tian Jianwei , Yu Zongchao , Liu Li , Wu Weidong , Zhu Hongyu , Liu Xuan
Published: May 2021

Smart Substation becomes more vulnerable to cyber attacks due to the high integration of information technologies, so it is essential to detect intrusion behaviour by abnormal traffic analysis in smart substations. Although there have been many detection methods for abnormal traffic, the existing ones all focus on the format check of a single field of the industrial transmission protocol, and ignore the deep coupling relationships among multiple protocol fields, which lead to more or less false detections and missed detections. To overcome this problem and further improve the detection accuracy, in this paper, we propose an abnormal traffic detection method based on the coupling field extraction and the density-based spatial clustering of applications with noise (DBSCAN). By using correlation analysis to extract the coupling fields of the protocol fields and using DBSCAN to remove the noise in the coupling fields, the deep coupling relationship between the coupling fields can be mined by the piecewise linear function fitting method, and used to detect abnormal traffic. The simulation results on 10,000 frames traffic prove that the proposed detection method can effectively identify the abnormal traffic.
The research of configuration for stability control device in smart substation
Authors: He Ye , Hu Binjiang , Chang Dongxu , Zhang Jie , Li Lingfang , Chen Yixuan
Published: May 2021

A unified specification to design and operate the stability control device in smart substation has not been formed yet, which has greatly affected the promotion and application of stability control device in smart substation. Thus, referring to the technical specifications of protection device and combining to the specificity of stability control device, a full and detailed configuration scheme is proposed to meet the requirement, including the device configuration principle, the access configuration of SV and GOOSE for variable primary connection types, the virtual terminal and soft switch. This solution is beneficial to standardize the R&D of stability control device in smart substation, and to facilitate on-site debugging, operation and maintenance.
Analysis of large-scale transmission line icing and galloping event in the Jilin province during November 2020
Authors: Xu Xunjian , Li Li
Published: May 2021

A large-scale transmission line icing and galloping event occurred in Jilin province during November 2020. First of all, the circulation background and the evolution characteristics of key meteorological factors of the icing and galloping event are analysed, which provide basis for the prediction and early warning of the galloping event in the future. It is found that, the warm and wet air transported northward to the central part of Northeast China due to the abnormal northward position of the western pacific subtropical high, combined with the strong cold air activity in the north, the cold and warm air converged in the middle of Northeast China, resulting in the co-occurrence of temperature decline, precipitation, gale and high humidity, which is the direct cause of this large-scale galloping event. Then, the prediction and actual situation of the disaster event are analysed. The results show that the power gird icing and galloping numerical prediction system accurately predicted the influence area and disaster intensity three days in advance, which can provide effective support for future disaster response. Finally, some relevant suggestions are put forward according to the characteristics of this disaster.
Method of building transformer acoustic diagnosis database based on multi physical field coupling modeling
Authors: Wu Weidong , Wu Zhengyang , Guo Shouchun , Lu Yulin , Ma Li , Wang Qinghua
Published: May 2021

In this paper, a method of building dynamic acoustic diagnosis database of dry-type transformer is proposed. The method is mainly combined with collecting the basic noise of transformer and simulating the acoustic signals of transformer under different working conditions to improve the fault database of transformer. Due to the incomplete working conditions on site, the simulated working conditions are relatively complete, and the marked acoustic signal file is generated, and then form the composition of the database. This paper focuses on the finite element simulation analysis of transformer vibration and noise radiation based on COMSOL, and the idea of establishing transformer biological diagnosis database. Improve the efficiency of transformer fault design and research, and provide reliable and convenient data services for researchers.
Analysis on the factors of daily electricity sales of urban and rural residents in Hunan province
Authors: Zhang Yun , Yan Huifeng , Zhou Xiao , Tang Jingyi
Published: May 2021

It’s of practical significance to explore the internal law of the fluctuation of the daily electricity sales of the urban and rural residents in Hunan province for the electricity planning and resource allocation in Hunan province. In this paper, after considering the economic meaning of electricity sales changes, a variety of factors were selected to influence the electricity sales of urban and rural residents in Hunan province, and the monthly residential electricity demand model from 2014 to 2019 was constructed, and the gradual regression was carried out. The results show that the per capita disposable monthly income (dpi) and non-comfortable days (ncd) have significant impacts on the electricity sales of urban and rural residents. And for every 1% increase in dpi or for each additional day of non-comfort days per month, the domestic electricity sales of urban and rural residents will increase by 0.49% or 0.01%. In addition, under high temperature and low temperature conditions, the influence of precipitation presents asymmetric characteristics.
Research on comprehensive load vibration test of electric vehicle motor controller unit
Authors: Yan Zhibiao , Zhao Lingxiao , Ma Huansheng
Published: May 2021

In this article, the vibration test standards and general test methods for electric vehicle motor control unit are introduced. New vibration test conditions are proposed based on the vibration data collected during the actual vehicle test. Using the vehicle output current data as the electrical load of the motor controller unit, and the temperature cycle as the environmental load, a comprehensive load vibration test method that integrates the electrical load and the environmental load is proposed. According to the test method, the equipment and test process of the comprehensive on-load vibration test of environmental load are determined. Summarized three important principles in the design of fixtures: lightweight, low damping, and no resonance. A novel testing method for motor controllers is proposed.
Facial expression recognition based on multi branch structure
Authors: Xie Yuqing , Huang Haichao , Hong Jianguang , Zhou Xianke , Wu Shilong , Lu Peng
Published: May 2021

Facial expression recognition (FER) is an important means for machines to perceive human emotions and interact with human beings. Most of the existing facial expression recognition methods only use a single convolutional neural network to extract the global features of the face. Some insignificant details and features with low frequency are easy to be ignored, and part of the facial features are lost. This paper proposes a facial expression recognition method based on multi branch structure, which extracts the global and detailed features of the face from the global and local aspects respectively, so as to make a more detailed representation of the facial expression and further improve the accuracy of facial expression recognition. Specifically, we first design a multi branch network, which takes Resnet-50 as the backbone network. The network structure after Conv Block3 is divided into three branches. The first branch is used to extract the global features of the face, and the second and third branches are used to cut the face into two parts and three parts after Conv Block5 to extract the detailed features of the face. Finally, the global features and detail features are fused in the full connection layer and input into the classifier for classification. The experimental results show that the accuracy of this method is 73.7%, which is 4% higher than that of traditional Resnet-50, which fully verifies the effectiveness of this method.
Approximate inertial manifold-based order reduction of rigid-flexible coupling manipulator
Authors: Xu Lisha , Qian Xiaoshan , Lin Chong
Published: May 2021

An order reduction method for the flexible deformation response analysis of rigid flexible manipulators is proposed based on the approximate inertial manifold theory. This method allows a lower dimensional simplified model to be constructed from a subspace smaller than the entire state space. In this paper, truncated three-order modes are used to construct a first-order system of AIM. Compared with the traditional Galerkin method, the results show that the proposed method can reduce the degree of freedom of the system and improve the computational efficiency without obviously losing the precision of the solution, which is convenient for the subsequent vibration analysis and controller design of the system.
Design and optimization of main reducer based on Baja racing
Authors: Ning Taiyu , He Chao , Chen Jifei , Liu Xueyuan , Chen Wengang , Wang Shuheng , Tang Jie
Published: May 2021

The main reducer is the main component of the whole vehicle, and its main function is to realize deceleration and torque increase. For Baha racing car, in order to improve the dynamic performance of the whole car, the main reducer is designed from the aspects of layout, transmission ratio distribution, shift mode, overall size and shell structure. Calculate the transmission ratio range of reducer according to the performance parameters of transmission parts, and verify the rationality of transmission ratio; Then determine the parameters of gear according to the transmission ratio and related parameters, and finally design the parameters of gear according to the transmission ratio and related parameters, and finally design the parameters of other parts of reducer. Based on the determined parameters, 3D modeling software UG is used to build 3D models of various parts of the reducer, and finite element analysis software ANSYS is used to simulate and analyze the parts to check whether the comprehensive mechanical properties meet the requirements. In this paper, the design of the main reducer realizes the comprehensive design of small size, light weight, reasonable transmission ratio distribution, high reliability, shifting gears during driving, and the comprehensive mechanical properties also meet the requirements.
Phenology and phylogeny of Hyalomma spp. ticks infesting one-humped camels (Camelus dromedarius) in the Tunisian Saharan bioclimatic zone
Authors: Elati Khawla , Bouaicha Faten , Dhibi Mokhtar , Ben Smida Boubaker , Mhadhbi Moez , Obara Isaiah , Amairia Safa , Bouajila Mohsen , Rischkowsky Barbara , Rekik Mourad , Gharbi Mohamed
Published: May 2021

In this study, we report the results of a survey of Hyalomma ticks infesting one-humped camels in southern Tunisia. Examinations were conducted every second or third month on 406 camels in Tataouine district from April 2018 to October 2019. A total of 1902 ticks belonging to the genus Hyalomma were collected. The ticks were identified as adult H. impeltatum (41.1%; n = 782), H. dromedarii (32.9%; n = 626), H. excavatum (25.9%; n = 493), and H. marginatum for a single specimen. Although the camels were infested by ticks throughout the year, the highest overall infestation prevalence was observed in April 2018 (p < 0.01). The overall infestation intensity varied between 2.7 and 7.4 ticks/animal. There were no statistically significant differences in tick infestation prevalence based on age categories of the camels, and the overall infestation prevalence was between 82.7% and 97.4%. Female camels were significantly more infested with ticks (88.3%) than males (65.5%) (p < 0.01). The infestation prevalence of camels varied significantly according to the region where sampling took place (p < 0.01), but no correlations were found with abiotic factors. The preferred attachment sites for adult Hyalomma ticks were the sternum (38.3%; n = 729/1902), around the anus (36.2%; n = 689/1902), udder (18.4%; n = 350/1902), and inner thigh (6.9%; n = 132/1902). Morphological classification of ticks was corroborated by sequencing the cytochrome c oxidase I (Cox1) and 16S rDNA genes, and these sequences were also used to infer phylogenetic relationships. A single H. dromedarii seemed to be a natural hybrid with H. rufipes. More attention should be devoted by the veterinary services to the infestation of camels by ticks.
Seroprevalence and associated risk factors of Toxoplasma gondii infection in yaks (Bos grunniens) on the Qinghai–Tibetan Plateau of China
Authors: Sun Tao , Rahman Sajid Ur , Cai Jinzhong , Zeng Jiangyong , Mi Rongsheng , Zhang Yehua , Gong Haiyan , Ma Hongcai , Huang Yan , Han Xiangan , Zhao Quan , Chen Zhaoguo
Published: May 2021

Toxoplasma gondii is an intracellular parasite that is extensively prevalent globally. Studies have indicated the presence of T. gondii infection in animals in some provinces of China, but little is known about T. gondii infection in yaks (Bos grunniens) on the Qinghai–Tibetan Plateau. In the current study, to determine the seroprevalence and associated risk factors of T. gondii, a total of 2784 serum samples were collected from 18 different sampling sites in eight counties of the Qinghai and Tibet regions of China from 2018 to 2019. Serum antibodies against T. gondii were detected in 261 yaks (9.38%) via enzyme-linked immunosorbent assay (ELISA). We found that seroprevalence differed significantly among different counties (ranging from 5.41% in Gangcha to 19.79% in Datong), by year in the Tibet Autonomous Region (from 2.34% in 2018 to 13.24% in 2019), and by age (from 5.59% in 0 < year ≤ 1 to 11.76% in year > 7) (p < 0.05). Climate, geographical conditions, and age are the main factors influencing T. gondii infection in yaks in these regions. Therefore, our study provides a data reference for public health and prevention of yak toxoplasmosis.
Prädiktoren der Legalbewährung nach forensischer Suchtbehandlung – Zweiter Teil einer Übersichtsarbeit zu Erfolgsdeterminanten einer Unterbringung gemäß § 64 StGB
Authors: Querengässer Jan , Baur Alexander
Published: May 2021

Hintergrund Ehe eine forensische Suchtbehandlung gemäß § 64 StGB gerichtlich angeordnet werden kann, ist eine Erfolgsprognose zu stellen und zu bejahen. Der Suche nach entsprechenden Prädiktoren für eine „hinreichend konkrete“ Erfolgsaussicht widmeten sich in den vergangenen Jahren einige Studien. Dabei stellt die Legalbewährung nach Entlassung das gesetzlich vorgesehene Erfolgskriterium forensischer Suchtbehandlung dar.

Zielsetzung Als zweiter Teil einer zweiteiligen Gesamtschau zu Erfolgsdeterminanten forensischer Suchtbehandlung gibt die vorliegende Arbeit einen Überblick über die aktuelle Befundlage zu Prädiktoren der Legalbewährung nach forensischer Suchtbehandlung und setzt diese in Beziehung zu der Studienlage bezüglich Prädiktoren des Entlassmodus.

Methodik Basierend auf systematischer Literaturrecherche werden dabei die Ergebnisse von acht empirischen Studien aus dem Zeitraum 2002–2019 vertieft aufbereitet und in einer Überblickstabelle dargestellt.

Ergebnisse Trotz im Detail heterogener Befunde weisen einerseits das Vorliegen motivationaler, lebenspraktischer und sozialer Ressourcen, andererseits die deliktische Vorgeschichte und Eigenschaften der aktuellen Delinquenz relativ klare Bezüge zur Legalbewährung nach erfolgter forensischer Suchtbehandlung auf. Zugleich treten bei ausschließlicher Betrachtung der Legalbewährung als einzigem Kriterium der Behandlungsprognose konzeptionelle Unschärfen zutage, da diese dann durch die Kriminalprognose überlagert wird.

Schlussfolgerung Die Grenzen des gegenwärtigen Forschungsstands legen für die Erstellung einer Behandlungsprognose gem. § 64 StGB ein zweischrittiges Vorgehen nahe: zunächst könnte anhand der Prädiktoren des Entlassmodus die Frage geprüft werden, als wie wahrscheinlich ein regulärer Therapieverlauf angesehen werden kann; sodann könnte anhand der Prädiktoren der Legalbewährung geprüft werden, ob auf eine rückfallpräventive Wirkung forensischer Suchtbehandlung geschlossen werden kann. Beide Teile der Übersichtsarbeit können forensisch-psychiatrische Sachverständige daher bei der Stellung einer reliablen Prognose der Behandlungsaussicht unterstützen. Ergänzend sollte überlegt werden, ob die Informationsgrundlage für Sachverständige etwa durch eine probatorische Phase verbessert werden könnte.
Diversity-Oriented Synthesis of Highly Functionalized Alicycles across Dipolar Cycloaddition/Metathesis Reaction
Authors: Kiss Loránd , Benke Zsanett , Nonn Melinda , Remete Attila M. , Fustero Santos
Published: May 2021

This Account gives an insight into the selective functionalization of some readily available commercial cyclodienes across simple chemical transformations into functionalized small-molecular scaffolds. The syntheses involved selective cycloadditions, followed by ring-opening metathesis (ROM) of the resulting azetidin-2-one derivatives or isoxazoline frameworks and selective cross metathesis (CM) by discrimination of the C=C bonds on the alkenylated heterocycles. The CM protocols have been described when investigated under various conditions with the purpose on exploring chemodifferentiation of the olefin bonds and a study on the access of the corresponding functionalized β-lactam or isoxazoline derivatives is presented. Due to the expanding importance of organofluorine chemistry in drug research as well as of the high biological potential of β-lactam derivatives several illustrative examples to the access of some fluorine-containing molecular entities is also presented in this synopsis.

1 Introduction

2 Ring C=C Bond Functionalization of Some Cycloalkene β-Amino Acid Derivatives across Chlorosulfonyl Isocyanate Cycloaddition

3 Ring C=C Bond Functionalization of Some Cycloalkene β-Amino Acid Derivatives across Nitrile Oxide Cycloaddition

4 Ring C=C Bond Functionalization of Some Cycloalkene β-Amino Acid Derivatives across Metathesis

5 Functionalization of sSome Cyclodienes across Nitrile Oxide Cycloaddition

6 Selective Synthesis of Functionalized Alicycles across Ring-Opening Metathesis

7 Selective Synthesis of Functionalized Alicycles through Cross Metathesis

8 Summary and Outlook

9 List of Abbreviations
Traumatic Spinal Cord Disorders: Current Topics and Future Directions
Authors: Huang Kevin T. , Lu Yi
Published: May 2021

Traumatic spinal cord injury (tSCI) is a life-changing and potentially overwhelming event. The sudden disruption of the spinal cord's integrity necessitates rapid attention at a specialized medical center, and involves a multilateral collaboration between neurologists, spine surgeons, critical care physicians, and trauma specialists. Even with care under ideal conditions, many tSCI patients have significant disability that persists for the rest of their lives. However, recently, we have seen a proliferation in clinical and translational trials that offer the promise that new treatments may be available soon.
Health Information System's Responses to COVID-19 Pandemic in China: A National Cross-sectional Study
Authors: Ye Jiancheng
Published: May 2021

Objective After the outbreak of the coronavirus disease 2019 (COVID-19) pandemic, Chinese hospitals and health information technology (HIT) vendors collaborated to provide comprehensive information technology support for pandemic prevention and control. This study aims to describe the responses from the health information systems (HIS) to the COVID-19 pandemic and provide empirical evidence in the application of emerging health technologies in China.

Methods This observational descriptive study utilized a nationally representative, cross-sectional survey of hospitals in China (N = 1,014) from 30 provincial administrative regions across the country. Participants include hospital managers, hospital information workers, and health care providers.

Results Among all the responses, the most popular interventions and applications include expert question-and-answer sessions and science popularization (61.74%) in online medical consultation, online appointment registration (58.97%) in online medical service, and remote consultation (75.15%) in telehealth service. A total of 63.71% of the participating hospitals expanded their fever clinics during the pandemic, 15.38% hospitals used new or upgraded mobile ward rounds systems, and 44.68% hospitals applied online self-service systems. Challenges and barriers include protecting network information security (57.00%) since some hospitals experienced cybersecurity incidents. 71.79% participants hope to shorten wait time and optimize the treatment process. Health care workers experienced increased amount of work during the pandemic, while hospital information departments did not experience significant changes in their workload.

Conclusion In the process of fighting against the COVID-19, hospitals have widely used traditional and emerging novel HITs. These technologies have strengthened the capacity of prevention and control of the pandemic and provided comprehensive information technology support while also improving accessibility and efficiency of health care delivery.
Effects of electron spatial inertia and magnetic field gradient on transport across magnetic filter
Authors: Lamari Y. , Oudini N. , Bendib A.
Published: May 2021

This work investigates, via particle-in-cell with Monte Carlo collision simulations, electron transport across magnetic filter (MF) in obstructed-drift plasma sources. The studied source consists of three stages, namely: the ionization stage where power is coupled to the plasma, the magnetic filter stage where the magnetic field strength is maximal and impedes electron transport, and the diffusion stage where most of the charged particles come from the first stage. The plasma source is schematized by a square whose walls (sides) are dielectric, except for the wall at the exhaust plane which is metallic and simulates a biased screen grid. As expected, our results show that as the plasma passes through the MF, electron density and temperature decrease. The electron flux and fluid velocity spatial distributions present an S-shaped path through which these plasma properties are significant. These high flux and fluid velocity are due to the superimposition of E×B and diamagnetic drifts that are enhanced by the walls. Moreover, at the entrance and exhaust of this S-shaped path, i.e., in the vicinity of the walls, the magnitude of the spatial inertia is significant in comparison to acceleration induced by an electric field and pressure gradient. The analytical analysis of this inertia shows that its magnitude and direction are mainly controlled by the gradients of the electric field, pressure force, electron density, and magnetic field strength. Therefore, the control of the spatial inertia, and thus, of electron flux across the magnetic filter, can be achieved by controlling the spatial distribution of the magnetic field strength.
Evaluation of degradation behavior in quantum dot light-emitting diode with different hole transport materials via transient electroluminescence
Authors: Doe Takahiro , Kitano Keisuke , Yamamoto Satoru , Yamamoto Masaki , Goto Kazuki , Sakakibara Yusuke , Kobashi Tadashi , Yamada Hirohisa , Ueda Masaya , Ryowa Tatsuya , Izumi Makoto , Arakawa Yasuhiko
Published: May 2021

In this study, we evaluated the degradation mechanism in quantum dot light-emitting diodes (QLEDs) to improve the device lifetime. We measured the hole mobility using the delay time of transient electroluminescence for three types of hole transport layer (HTL) materials. In addition, we estimated the degradation of luminance efficiency and hole mobility under constant current drive. As a result, the HTL material with a higher hole mobility yielded longer QLED device lifetimes. Through substitution of the HTL material from poly (9-vinylcarbazole) (PVK) to poly [(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)] (TFB), the hole mobility and the 95% luminance lifetime from initial luminance improved from 0.5 × 10−5 cm2/V⋅s and 2.90 h at J = 10 mA/cm2 to 1.1 × 10−5 cm2/V⋅s and 179 h, respectively. Moreover, we clarified that the degradation of the luminescent efficiency is correlated with the hole mobility.
Comparison of supercavity geometry and gas leakage behavior between the double-cavity flow pattern and the wake-closure flow pattern
Authors: Xu Haiyu , Luo Kai , Dang Jianjun , Li Daijin , Ye Changsheng , Huang Chuang
Published: May 2021

The objective of this paper is to investigate the effect of two typical supercavity flow patterns (double-cavity and wake-closure) on ventilated supercavity geometry and supercavitating flow structure and further reveal the different mechanisms of gas leakage for these two supercavity flow patterns. An inhomogeneous multiphase model with shear stress transport turbulence was employed to validate the investigation by experimental results. The supercavity geometry was investigated quantitatively between the two supercavity flow patterns by the contrast, and corresponding gas leakage mechanisms were determined. The results show that compared with those of the wake-closure flow pattern, the maximum diameter and full-length of the supercavity with the double-cavity flow pattern decreased by 9.83% and 35.8%, respectively, under the same gas entrainment coefficient. The reason for the apparent difference in the supercavity dimension between the two supercavity flow patterns is that the amount of gas leaking from the closure region is different. For the wake-closure flow pattern, about 6.0% of the ventilated gas leaks from the closure region. However, for the double-cavity flow pattern, more gas leaks from the closure region, which is about four times that of the wake-closure flow pattern. As a result, the mass flow rate of the reverse gas decreases, leading to a decrease in the size of the region where gas flows reversely.
Eigenmode characterizations of slab ion-temperature-gradient instabilities in various magnetic shear configurations
Authors: Ren Guangzhi , Wei Lai , Yu Fang , Wang Zheng-Xiong , Li Jiquan
Published: May 2021

Comprehensive eigenmode characterizations of ion-temperature-gradient (ITG) instabilities in slab geometries with different magnetic shear profiles are investigated using an eigenvalue method. The results in the uniform magnetic shear configuration are verified via the Hamaguchi–Horton theory [S. Hamaguchi and W. Horton, Phys. Fluids B 2, 1833 (1990)]. However, it is interestingly found that the linear growth rate and mode frequency change non-monotonically as the magnetic shear at the half simulation domain s(x < x0) changes continuously from the positive value to the negative value. There are multiple peaks in the dependence curve of the linear growth rate on s(x < x0) in the weak magnetic shear regime. The variation of magnetic shear, which can produce an additional potential well to excite instability, is identified to play an important role in the maximization of the growth rate of slab ITG modes. In the configuration with a moderate separation between two potential wells, multiple ITG modes with higher radial wave numbers l become unstable simultaneously. While |s(x < x0)| is weak compared to the local magnetic shear s(x = x0) at the center mode rational surface, asymmetric structures of low-order eigenmodes are obtained and high-order eigenmodes tend to be localized between two potential wells. Additionally, as the separation between two rational surfaces in the negative shear configuration further decreases, the high-order-l eigenmode would be stabilized. The mode structures of the low-order-l unstable eigenmode are present between two rational surfaces.
Tunable topological Hall effects in noncollinear antiferromagnet Mn3Sn/Pt bilayers
Authors: Cheng Yang , Yu Sisheng , Zhu Menglin , Hwang Jinwoo , Yang Fengyuan
Published: May 2021

Noncollinear antiferromagnet Mn3Sn has attracted wide interest as it is a candidate for Weyl semimetal. Here, we report the observation of topological Hall like signals in Mn3Sn/Pt bilayers grown on Al2O3(0001). X-ray diffraction and scanning transmission electron microscopy results confirm the high epitaxial quality of the c-axis-oriented Mn3Sn films. The detected topological Hall resistivity shows a broad temperature range from 210 to 365 K by tuning the thickness of Mn3Sn from 3 to 15 nm. Compared with previously reported topological Hall effects in Mn3Sn at temperatures below 50 K, the observed high-temperature topological Hall signal is likely due to the stabilization of topological spin textures enabled by the strong spin–orbit coupling of the Pt overlayer and the Dzyaloshinskii–Moriya interaction at the Mn3Sn/Pt interface.
Native oxide reconstructions on AlN and GaN (0001) surfaces
Authors: Mirrielees Kelsey J. , Dycus J. Houston , Baker Jonathon N. , Reddy Pramod , Collazo Ramón , Sitar Zlatko , LeBeau James M. , Irving Douglas L.
Published: May 2021

Properties of AlN/GaN surfaces are important for realizing the tunability of devices, as the presence of surface states contributes to Fermi level pinning. This pinning can influence the performance of high electron mobility transistors and is also important for passivation of the surface when developing high-power electronic devices. It is widely understood that both AlN and GaN surfaces oxidize. Since there are many possible reconstructions for each surface, it is a challenge to identify the relevant surface reconstructions in advance of a detailed simulation. Because of this, different approaches are often employed to down select initial structures to reduce the computational load. These approaches usually rely on either electron counting rules or oxide stoichiometry, as both of these models tend to lead to structures that are energetically favorable. Here we explore models from these approaches but also explore a reconstruction of the (0001) surface directly observed using scanning transmission electron microscopy with predictive density functional theory simulations. Two compositions of the observed surface reconstruction—one which obeys oxide stoichiometry and one which is cation deficient and obeys electron counting—are compared to reconstructions from the previous work. Furthermore, surface states are directly calculated using hybrid exchange-correlation functionals that correct for the underestimation of the bandgaps in AlN and GaN and improve the predicted positions of surface states within the gap. It is found that cation deficiency in the observed reconstruction yields surface states consistent with the experiment. Based on all of these results, we provide insight into the observed properties of oxidized AlGaN surfaces.
Programming patchy particles to form three-dimensional dodecagonal quasicrystals
Authors: Tracey Daniel F. , Noya Eva G. , Doye Jonathan P. K.
Published: May 2021

Model patchy particles have been shown to be able to form a wide variety of structures, including symmetric clusters, complex crystals, and even two-dimensional quasicrystals. Here, we investigate whether we can design patchy particles that form three-dimensional quasicrystals, in particular targeting a quasicrystal with dodecagonal symmetry that is made up of stacks of two-dimensional quasicrystalline layers. We obtain two designs that are able to form such a dodecagonal quasicrystal in annealing simulations. The first is a one-component system of seven-patch particles but with wide patches that allow them to adopt both seven- and eight-coordinated environments. The second is a ternary system that contains a mixture of seven- and eight-patch particles and is likely to be more realizable in experiments, for example, using DNA origami. One interesting feature of the first system is that the resulting quasicrystals very often contain a screw dislocation.
Method to suppress antiferromagnetic skyrmion deformation in high speed racetrack devices
Authors: Roy P. E.
Published: May 2021

A method for enhancing the stability of high speed antiferromagnetic skyrmions in racetrack devices is proposed and demonstrated numerically. Spatial modulation of the Dzyaloshinskii–Moriya interaction via a patterned top heavy metal gives rise to a strong confining potential. This counteracts skyrmion deformation perpendicular to the direction of propagation and the subsequent annihilation on contact with the racetrack’s horizontal boundaries. An achievable increase in the maximum driving current density of 135%, enabling higher velocities of 28%, is predicted. Furthermore, an extended saturating behavior of the mobility relation due to the imposed confinement is also found at large driving amplitudes, further enhancing skyrmion stability at high velocities.
Predicting Hugoniot equation of state in erythritol with ab initio and reactive molecular dynamics
Authors: Hu Jing , Wilde Zakary , Peralta Pedro , Muhich Christopher , Oswald Jay
Published: May 2021

Erythritol has been proposed as an inert surrogate for developing theoretical and computational models to study aging in energetic materials. In this work, we present a comparison of mechanical and shock properties of erythritol computed using the ReaxFF reactive force field and from ab initio calculations employing density functional theory (DFT). We screened eight different ReaxFF parameterizations, of which the CHO parameters developed for hydrocarbon oxidation provide the most accurate predictions of mechanical properties and the crystal structure of erythritol. Further validation of the applicability of this ReaxFF parameterization for modeling erythritol is demonstrated by comparing predictions of the elastic constants, crystal structure, vibrational density of states, and Hugoniot curves against DFT calculations. The ReaxFF predictions are in close agreement with the DFT simulations for the elastic constants and shock Hugoniot when the crystal is loaded along its c axis but show as much as 30% disagreement in the elastic constants in the ab plane and 12% difference in shock pressures when shocked along the a or b crystal axes. Last, we compare thermomechanical properties predicted from classical molecular dynamics with those calculated using the quasi-harmonic approximation and show that quantum mechanical effects produce large discrepancies in the computed values of heat capacity and thermal expansion coefficients compared with classical assumptions. Combining classical molecular dynamics predictions of mechanical behavior with phonon-based calculations of thermal behaviors, we show that predicted shock-induced temperatures for pressures up to 6.5 GPa do not exceed the pressure-dependent melting point of erythritol.
Interface charge transport of multilayer devices for exact analysis of charge behavior in organic optoelectronic devices
Authors: Kim Jae-Min , Lee Kyung Hyung , Lim Junseop , Lee Jun Yeob
Published: May 2021

A unipolar charge device was utilized to gain information of the charge balance in organic optoelectronic devices to enhance efficiency and operational stability. Usually, a unipolar charge device is designed as a multilayer structure to improve charge transport and block injection of counter charges from electrodes. In this paper, the correlation between charge transport across the interlayer and corresponding bulk electrical parameters from quasi-static analysis was investigated. Although only the interlayer material was modified, the charge carrier mobility and drift charge carrier density of the light-emitting layer were totally changed, which originated from large series resistance due to charge accumulation at the interface. This result indicates that quantitative analysis of electrical properties from unipolar charge devices should be performed as background analysis to ensure efficient interface charge transport during operation.