bluuebunny/crossref_metadata_2025 huggingface dataset:
Model‐free output feedback discrete sliding mode control with disturbance compensation for precision motion systems
Authors: Li Min , Tan Shuhua , Xiong Jiaxi , Gan Jinqiang , Zhang Xinxin
Published: May 2020

This study proposes a novel model‐free output feedback discrete sliding mode control (OFDSMC) with disturbance compensation to achieve high performance for precision motion systems encountering model uncertainties and disturbances. Traditional discrete sliding mode control design requires model and/or state information. In this study, OFDSMC with disturbance compensation is first developed by using a parametric input–output model such that no system states are needed. The essential four control terms of OFDSMC with disturbance compensation is revealed. Then a data‐driven control method is introduced into OFDSMC to eliminate the need for the parametric model. The proposed model‐free OFDSMC facilitates a rapid implementation without either a parameter model or a state observer, and achieves good robustness against model uncertainties and disturbances. Finally, three simulation cases are presented to illustrate the effectiveness and enhanced performance of the proposed approach.
Security improved duobinary optical communication scheme through bio‐inspired chaos masking scheme
Authors: Ravindran Sornalatha , Nithiyanantham Janakiraman
Published: May 2020

In optical fibre communication system, improved modulation schemes have been proposed to increase capability and high bit rate transmission. One such technique is optical duobinary modulation, which can able to broadcast high‐speed optical signals over bandwidth‐limited channels. The conventional modulation schemes employ the non‐return‐to‐zero modulation and return‐to‐zero modulation technique. These schemes decrease spectrum width and increase the dispersion tolerance. However, the effect of inter‐symbol inference presents between the pulses. These techniques give a reduced performance for high bit rate transmissions and transmission over long distances. Hence in this work, the implementation of duobinary modulation improves the performance of optical communication along with the provision of enhanced security through bio‐inspired chaos masking scheme. The bio‐inspired chaos‐masking scheme generates the security key using the spider security pattern generator to provide improved security. The parameters of the proposed technique are analysed for different transmission rates and the performance improvement is validated.
Modular solid‐state pulse generator based on multi‐turn LTD
Authors: Dong Shoulong , Wang Yilin , Ma Jianhao , Zeng Weirong , He Yingjiang , Yu Liang , Hu Yuye , Zhang Shuo , Yao Chenguo
Published: May 2020

A modular solid‐state pulse generator based on a multi‐turn linear transformer driver (LTD) is designed for the application of pulse power techniques with a high voltage, large current and wide pulse width. The LTD adopts the method of multi‐turn winding on the magnetic core, which can help to output pulses of wide width. The isolation of the power supply with windings in the same direction of the LTD modules is designed, and the isolation voltage of the magnetic cores is the working voltage of the LTD modules. A modular solid‐state pulse generator based on the multi‐turn LTD is developed, which is composed of 10 LTD modules. Each module consists of 18 energy storage capacitors, metal‐oxide‐semiconductor field‐effect transistors and their driving circuits connected in parallel. The pulse generator can output pulses with parameters including a voltage ranging from 0 to 5000 V, a pulse current up to −500 A, and a pulse width ranging from 200 ns to 5 μs. When all modules work in synchronisation, rectangular pulses can be produced with a rise time of 30 ns and a fall time of 16 ns. If all modules are asynchronised, trapezoidal pulses are produced with adjustable step‐like rising and falling edges. Moreover, a higher‐voltage pulse can be achieved by increasing the number of LTD modules.
Sliding mode control with open‐switch fault diagnosis and sensorless estimation based on PI observer for PMSM drive connected with an LC filter
Authors: Wang Minghui , Xu Yongxiang , Zou Jibin
Published: May 2020

In some cases, LC filters are installed between the inverters and motors to suppress the adverse effects of pulse width modulation. However, some techniques should be modified, because the mathematical model of the drive system is changed by the LC filter and the sensors on the inverter output cannot measure some necessary variables. In this study, a multi‐purpose proportional‐integral (PI) observer is proposed at first. The type of observer depends on whether the position sensor is equipped. A sliding mode controller for the LC filter based on the observer is presented, therefore improving the dynamic performance. Furthermore, if the position sensor of the rotor is equipped, an open‐switch fault diagnostic method is realised by means of the PI observer; if the position sensor is not equipped, the sensorless estimation is realized. The proposed strategies were realised without any additional current/voltage sensors. Experimental results verified the effectiveness of the proposed strategies.
Harmonic and unbalanced voltage compensation with VOC‐based three‐phase four‐leg inverters in islanded microgrids
Authors: Tran Trung , Raisz David , Monti Antonello
Published: May 2020

This study proposes a novel method that combines sliding mode control (SMC) and virtual oscillator control (VOC) to eliminate voltage harmonics and unbalance caused by non‐linear and unbalanced loads in a three‐phase low‐voltage microgrid. The conventional VOC is modified to fit the three‐phase four‐leg inverter systems and a novel SMC control is designed using the high‐pass filter technique and linearised super twist algorithm. The proposed control method can keep the voltage harmonics and unbalance at the point of common coupling within the IEEE standard limits, under heavily non‐linear and unbalanced load conditions. The validity of the proposed method is verified by both offline simulations in Matlab/Simulink and Control Hardware‐in‐the Loop simulations using an OPAL‐RT platform.
Cooperative localisation for deep‐sea exploration using multiple unmanned underwater vehicles
Authors: Kim Jonghoek
Published: May 2020

This study considers cooperative localisation and exploration of multiple unmanned underwater vehicles. The author assumes that one vehicle, called the communication/navigation aid (CNA), moves near the sea surface and that the vehicle can use a global positioning system (GPS) to localise itself. To explore a deep sea, the author's strategy is to make each vehicle move at a distinct depth such that a communication link is maintained during the manoeuvre. For cooperative localisation and exploration, the CNA uses GPS to localise itself, while each vehicle measures the bearing and range of its nearby vehicle and has a depth sensor to measure its depth. The effectiveness of the proposed control scheme is verified utilising MATLAB simulations.
Molecular globules in the Veil bubble of Orion
Authors: Goicoechea J. R. , Pabst C. H. M. , Kabanovic S. , Santa-Maria M. G. , Marcelino N. , Tielens A. G. G. M. , Hacar A. , Berné O. , Buchbender C. , Cuadrado S. , Higgins R. , Kramer C. , Stutzki J. , Suri S. , Teyssier D. , Wolfire M.
Published: May 2020

Strong winds and ultraviolet (UV) radiation from O-type stars disrupt and ionize their molecular core birthplaces, sweeping up material into parsec-size shells. Owing to dissociation by starlight, the thinnest shells are expected to host low molecular abundances and therefore little star formation. Here, we expand previous maps made with observations using the IRAM 30 m telescope (at 11″ ≃ 4500 AU resolution) and present square-degree12CO and13CO (J= 2–1) maps of the wind-driven “Veil bubble” that surrounds the Trapezium cluster and its natal Orion molecular core (OMC). Although widespread and extended CO emission is largely absent from the Veil, we show that several CO “globules” exist that are blueshifted in velocity with respect to OMC and are embedded in the [C II] 158μm-bright shell that confines the bubble. This includes the first detection of quiescent CO at negative local standard of rest velocities in Orion. Given the harsh UV irradiation conditions in this translucent material, the detection of CO globules is surprising. These globules are small (Rg= 7100 AU), not massive (Mg= 0.3M⊙), and are moderately dense:nH= 4 × 104cm−3(median values). They are confined by the external pressure of the shell,Pext∕k≳ 107cm−3K, and are likely magnetically supported. They are either transient objects formed by instabilities or have detached from pre-existing molecular structures, sculpted by the passing shock associated with the expanding shell and by UV radiation from the Trapezium. Some represent the first stages in the formation of small pillars, others of isolated small globules. Although their masses (Mg<MJeans) do not suggest they will form stars, one globule matches the position of a known young stellar object. The lack of extended CO in the “Veil shell” demonstrates that feedback from massive stars expels, agitates, and reprocesses most of the disrupted molecular cloud gas, thereby limiting the star-formation rate in the region. The presence of molecular globules is a result of this feedback.
The K supergiant runaway star HD 137071
Authors: Comerón F. , Figueras F.
Published: May 2020

Context. Extensive work exists on runaway massive stars with peculiar motions that are much higher than those typical of the extreme Population I to which they belong. Work on runaways has focused almost exclusively on O and B stars, most of which undergo a red supergiant phase before ending their lives as supernovae. Very few examples are known of red supergiant runaways, all of which descend from the more massive O-type precursors, but none from the lower mass B-type precursors, although runaway statistics of B-type stars suggest that K-type runaways must be relatively numerous.

Aims. We study HD 137071, a star that has so far been considered to be a normal K-type red giant. Its parallax measured by Gaia and the derived luminosity suggest that it is a supergiant, whereas its derived distance to the Galactic plane and its spatial velocity of 54.1 km s−1 with respect to the local standard of rest suggest that it is also a runaway star. However, intrinsic limitations in determining the trigonometric parallaxes of cool supergiants, even in the Gaia era, require accurate spectral classifications for confirmation.

Methods. We present visible spectroscopy obtained with the 2.2m telescope at Calar Alto Observatory and compare it with the spectra of MK standard stars to produce an accurate spectral classification, including the determination of its luminosity class. We complement this information with astrometric data from the Gaia DR2 catalog.

Results. We reliably classify HD 137071 as a K4II star and establish its membership to the extreme Population I. This agrees with the luminosity derived using the Gaia DR2 parallax measurement. Kinematical data from the Gaia DR2 catalog confirm its high spatial velocity and runaway nature. By combining the spectral classification with astrometric information, recent Galactic potential models, and evolutionary models for high-mass stars, we trace the motion of HD 137071 back to the proximities of the Galactic plane and speculate which of the two proposed mechanisms for the production of runaway stars may be responsible for the high velocity of HD 137071. The available data favor the formation of HD 137071 in a massive binary system where the more massive companion underwent a supernova explosion about 32 Myr ago.
Geoelectrical tomography data processing and interpretation for Pb-Zn-Ag mineral exploration in Nash Creek, Canada
Authors: Ali Mosaad , Sun Shulin , Qian Wei , Bohari Abdou Dodo , Claire Dusabemariya , Zhang Yan
Published: May 2020

The geoelectrical tomography survey was carried out to explore and characterize a (Zn-Pb-Ag) sulphide deposit in Nash Creek (NC), New Brunswick province, Canada. The exploration strategy has been conducted by the 2-D survey for a well-cut grid consisting of twelve surface lines (profiles) each around 2 km long, and 300 m apart, for the total area around 9.5 km2. The datasets (resistivity and induced polarization) were acquired using the Iris El-Rec Pro system with pole-dipole electrodes array spaced 50 m apart, and ten levels of data datum. The results of the 2-D inversion revealed that the underground resistivity and chargeability values in the exploration area have a range of (5 to 1300 Ωm) and (0-9.5 mV/V), respectively. The sulphide mineralization zones in the exploration area are characterized by moderate resistivity values (150-300 Ωm) and moderate to low chargeability values (>5.5 mV/V), with a depth of around (90140 m) from the surface. The 3-D visualization model clearly reveals that three main zones of sulphide mineralization are present in the exploration area. The predicted geological reserve of the sulphide ore in the exploration area was calculated. The inverted models revealed a good agreement with the existing geological features in the exploration area.
Mining processes of brick products in the Czech Republic
Authors: Fiala Jan , Lapka Miroslav , Fiala jun Jan , Mikolas Milan
Published: May 2020

First technological process, which ceramic producers of ceramic products use for their future ceramic product is mining process. Mining methods, Transport methods and processing methods are basic technological processes. The process of drying, firing and shaping of brick products are specific. Babylonian gardens, Hagia Sofia, are one of the most beautiful churches that has ever been built. The great Wall of China, medieval castle Malbork from northern Poland not far from Gdansk`s bay which resembles small town, Skyscraper Chrysler Building in New York are the outstanding brick creations in the world. All of these buildings have one thing in common and that is material from which they were built. The material is brick, one of the simplest, the most beautiful, the most universal and the oldest building product which is known for moreover than 10 000 years [1]. Brick association of Czech and Moravia, nowadays unites 6 regular members with 19 plants where are created fired building materials. Furthermore it unites 7 associated members who ensure various services for brickmakers and 7 honorary members. Producers, members of brick association represent 92 % of Mason material capacity in the Czech Republic and 100 % of fired roofing tile capacity.
Transport routes on technological lines and following problems
Authors: Fiala Jan , Lapka Miroslav , Fiala jun Jan , Mikolas Milan
Published: May 2020

The article points out problems occurring on transport routes within the transfer of mind materials on technological lines for processing of raw materials, find possible solutions in increasing the lifetime of individual parts and in the area of maintenance and serviceability helps to Protect the health of employees of mining organizations and their suppliers. It conceives the problem of running a technology line as one big unit that combines innovative solutions with the use of modern materials. Increasing service life, reducing repair costs and reducing the frequency of repairs especially those cyclically recurring. All of this helps to eliminate the number of accidents and this is why it protects the operator of the technology line. Ultimately maintenance costs are streamlined despite the relatively higher initial cost.
Current trends in the development of automation surveying support in the construction of subways
Authors: Khakimov Abduboki , Kutumova Gullola , Mirzaeva Zamira
Published: May 2020

The article discusses the basic principles and conditions for the use of the latest underground navigation system. An example is given of the second new Yunusabad line of the Tashkent Subway using the shield method. For the first time in the Republic of Uzbekistan, in the construction of the Tashkent metro stations by underground, the Tunneling Mechanized Complex (TMC) was used - a movable prefabricated metal structure manufactured in Germany by the company HERRENKNECHT, which is the leading company in the world and produces machines for the construction of tunnels of any diameter in the range from 0.10 to 19 m in any engineering-geological conditions. The disadvantages and advantages of the underground navigation system are indicated; conclusions are drawn about the prospects for its application. The patterns of development of technical aspects of the automation of surveying concerning general historical trends are examined.
Automated determination of internal points of the coordinate grid of the blasted rock mass
Authors: Rakishev Bayan , Rakisheva Zaure , Auezova Alma , Orynbay Аsfandiyar
Published: May 2020

An automated method for determining the internal points of the coordinate grid of the blasted rock mass is described. It is based on the method of determining the nodal points of the coordinate grid of the blasted rock mass, which is based on taking into account the dependencies that connect the initial parameters of the blasting rock mass with the final location of the fixed points of the blasted rock mass. The determining factors are the specific height and width of the collapse, the coefficient of loosening of the rocks. The method of analysis of experimental and industrial mass explosions in quarries, methods of analytical geometry, matrix theory and linear algebra are used. For the first time in mining, an analytical method has been developed for determining the internal points of the coordinate grid of an exploded block. It includes the established functions of the movement of nodal points, components of the vectors of movement of nodal and internal points of the coordinate grid. The established dependencies allow one to determine the displacements of any point inside the coordinate grid of the blasted block from the initial coordinates of the nodal and internal points.
Polymer concrete and fibre concrete as efficient materials for manufacture of gear cases and pumps
Authors: Yelemessov Kassym , Krupnik Leonid , Bortebayev Sayin , Beisenov Bauyirzhan , Baskanbayeva Dinara , Igbayeva Akzhan
Published: May 2020

The paper describes the results of investigations on application of composite materials – polymer concrete and fibre concrete for manufacture gear cases of mechanisms used in mining and metallurgical industry centrifugal pump casings. The methods of establishing efficient compositions of polymer concrete and fibre concrete, based on a filler with gapped grading in which the pinholes in coarse fractions are filled with smaller fractions have been developed. After hardening, such mixtures have the strength 1.5...2 times higher than the items made of metal. The efficient additive of steel fibre to fibre concrete has been identified which improves the strength characteristics. The regularities of the impact on the strength and structure of polymer concrete and fibre concrete of the rotation frequency of the working element of the mixer and time of mixing the mixture components are identified. TS-250 gear and centrifugal pump casings are made by casting method and are tested on a test bed. The results obtained make it possible for us to recommend the developed compositions of polymer concrete and fibre concrete for application in engineering industry to manufacture gear and centrifugal pump casings.
Specific Issues with Liquidation of the Mineral Deposit in Vazany by the Kromeriz
Authors: Zidek Martin , Vokurka Michal
Published: May 2020

This paper investigates the problematic liquidation of now unused deposit of brick clay in south – eastern part of Czech Republic approximately 1.5 km to SW from the city centre of Kromeriz. Initially the condition of the deposit is described from the time of closure to the present day, including a detailed discussion of the problem. Main part of this paper is devoted to the design concept of reclamation of the unused deposit. The purpose and aim of this conception is to design a proposal of technical and biotechnical measures to create conditions for full-fledged reintegration of this segment of land, affected by mining, into it´s surrounding area. The conception summarises the whole scale of necessary tasks needed to achieve remediation and reclamation of the area.
The determination of the influence degree of mining-geological and mining-technical factors on the safety of the degassing system
Authors: Ahaiev Ruslan , Prytula Dmytro , Kliuiev Eduard , Zhytlonok Dmytro , Cabana Edgar , Kabakova Liudmyla
Published: May 2020

This article presents the results of the calculation of methane emission from the development of coal seam and enclosing rocks in the roof on Mine Management “Sukhodolska-Skhidna”. The required degassing efficiency and the degassing method were determined. The degree of influence of mining -technical and mining-geological factors on the safety of the degassing system has established. The determination of the influence degree of mining factors on the safety of the degassing system can be used both at the design stage mine, mining and preparing it, which allow to predict and prevent the formation of an explosive concentration of methane-air mixture.
Energy estimation of the interaction of a roller vibratory classifier’s blade with crushed rock mass for solving design problems
Authors: Nadutyi Volodymyr , Chеlyshkinа Valentyna , Sukhariev Vitalii , Haddad Jamil
Published: May 2020

The roller vibratory classifier is equipped with an impact device for implementing vibro-shock mode, which improves the classification efficiency, especially of viscous and wet materials. The new device is a disk nozzle with blades, which are made like petals of wearresistant polymer. The immersion of a petal at a given depth in a crushed rock mass is investigated experimentally. Theoretical studies includes pair correlation and regression analysis methods. It is obtained that an increase in humidity promotes penetration and leads to a decrease in the energy necessary for impact, whereas an increase in particle size and layer thickness leads to its increase. Analysis of regression equations makes it possible to establish the percentage ratio of influencing factors. The article presents mathematical models of impact energy from variable factors for the initial moisture content of the material, including separately for small classes (-2.5 + 1) mm and further, with variation of all three parameters in the range: layer thickness – 20-40 mm, particle size 1-10 mm, humidity – up to 9 %. The obtained correlation dependencies and regression models are necessary for improving the existing and designing new blade-type roller vibratory classifiers.
Development of digital technologies for the systems of remote mining safety monitoring
Authors: Slashchov Ihor , Slashchov Anton , Siromaschenko Illya , Kurinnyi Volodymyr , Ikonnikov Maksym
Published: May 2020

The article is devoted to development of methodology and digital technologies for assessing, forecasting and determining scenarios of geomechanical process evolution. A new digital technology is proposed for remote mining safety monitoring, which integrates a network personnel management system and expert subsystems for decision-making support taking into account geomechanical factors presenting risk of the mine roadway stability loss. Elements of the expert subsystems analyze data in real time, and are used to determine potential risks on basis of criteria and assessments of the production environment state in mines. It is proposed to identify the forecast safety indicators with the help of geomechanical models and by assessing scenarios of the “support-rocks” system stressstrain state evolution. In order the expert assessment of the rock massif and mine roadway stability, integral indicators of emergency potential risk for each geotechnical system elements are specified by values of informative parameters at a certain time point, as well as deviations rates of parameters from the equilibrium point over a period of time. Job safety is provided through the improved effectiveness of personnel interaction and its stricter disciplinary responsibility, as well as by making early decisions on keeping the mine roadways in a trouble-free condition.
The results of monitoring of hydroimpulsive disintegration of outburst-prone coal seams using ZUA-98 system
Authors: Zberovskyi Vasyl , Sofiiskyi Kostiantyn , Stasevych Rishard , Pazynych Artem , Pinka Jan , Sidorova Marina
Published: May 2020

The paper represents the results of monitoring and evaluation of the efficiency of hydroimpulsive disintegration of outburst-prone coal seams in the stopes of development mine workings using a system of sound detecting facilities. Methods of acoustic emission control have been considered as well as the monitoring tasks to evaluate rock mass conditions before the procedure and after it inclusive of the results of sound accompaniment of hydraulic disintegration of the coal seam. It has been determined that the higher concentration of stresses within the rock mass is, the more efficient action of high frequency self-oscillations of cavitation transmitter is on both the fissuring and changes in gas-dynamic state of the coal seam. It has been recommended to apply a mode of impulsive fluid pumping under the conditions where coal seam is in the stress-strain state.
Study on optimization of thermal spinning process of accumulator shell
Authors: Li Bin , Li Yunan , Zhu Peihao , Ma Wenpeng , Xiao Yinhong , Li Xiang
Published: May 2020

In view of the shortcomings of the existing hot spinning process technology of the accumulator shell, a method for optimizing the multi-spinning process parameters is proposed. The Johnson-Cook constitutive model of the accumulator shell material – 34CrMo4 alloy steel − was established with its parameters obtained experimentally. The finite element simulation was carried out for the hot spinning and closing process. Based on which, three parameters with the greatest influence on the spinning formation were studied: spinning temperature, spindle speed and friction coefficient. Combined with the central composite test, the response surface model and the mapping relationship between the three parameters and the maximum mises stress as well as the maximum wall thickness increment of the shell were established. The Pareto optimized solution set was obtained through multi-objective optimization. Under the condition of not affecting product quality, the optimized solution with low spinning temperature and high spindle speed is selected to reduce energy loss and improve work efficiency. The results indicate that the optimized process is experimentally verified to reduce the process temperature by nearly 30 °C, and the efficiency is increased by 25%.
COVID-19: Ophthalmological Aspects of the SARS-CoV 2 Global Pandemic
Authors: Siedlecki Jakob , Brantl Victor , Schworm Benedikt , Mayer Wolfgang Johann , Gerhardt Maximilian , Michalakis Stylianos , Kreutzer Thomas , Priglinger Siegfried
Published: May 2020

Purpose To perform a systematic analysis of articles on the ophthalmological implications of the global COVID-19 pandemic.

Methods PubMed.gov was searched for relevant articles using the keywords “COVID-19”, “coronavirus”, and “SARS-CoV-2” in conjunction with “ophthalmology” and “eye”. Moreover, official recommendations of ophthalmological societies were systematically reviewed, with a focus on the American Academy of Ophthalmology (AAO) and the Royal College of Ophthalmologists (RCOphth).

Results As of April 16, 2020, in total, 21 peer-reviewed articles on the ophthalmological aspects of COVID-19 were identified. Of these, 12 (57.1%) were from Asia, 6 (28.6%) from the United States of America, and 3 (14.3%) from Europe. There were 5 (23.8%) original studies, 10 (47.6%) letters, 3 (14.2%) case reports, and 3 (14.2%) reviews. These articles could be classified into the topics “Modes and prevention of (ocular) transmission”, “Ophthalmological manifestations of COVID-19”, “Clinical guidance concerning ophthalmological practice during the COVID-19 pandemic”, and “Practical recommendations for clinical infrastructure”. Practical recommendations could be extracted from official statements of the AAO and the RCOphth.

Conclusion Within a short period, a growing body of articles has started to elucidate the ophthalmological implications of COVID-19. As the eye can represent a route of infection (actively via tears and passively via the nasoacrimal duct), ophthalmological care has to undergo substantial modifications during this pandemic. In the eye, COVID-19 can manifest as keratoconjunctivitis.
Osteoradionecrosis of the Maxilla: Conservative Management and Reconstructive Considerations
Authors: Shokri Tom , Wang Weitao , Vincent Aurora , Cohn Jason E. , Kadakia Sameep , Ducic Yadranko
Published: May 2020

The implementation of radiotherapy in the multimodal treatment of advanced head and neck cancer has greatly improved survival rates. In some patients, however, this benefit comes at the potential expense of the tissue surrounding the primary site of malignancy. Osteoradionecrosis (ORN) of the facial bones, in particular the maxilla, is a debilitating complication of radiation therapy. Exposure to ionizing radiation results in devitalization of underlying bone with necrosis of adjacent soft tissue. Controversy surrounding appropriate early intervention in ORN persists and no consensus for clinical treatment has been established. In the present article, we review the pathophysiology of maxillary ORN and discuss the role of both conservative medical therapy and reconstruction.
Prevention and Treatment of Venous Thromboembolism Associated with Coronavirus Disease 2019 Infection: A Consensus Statement before Guidelines
Authors: Zhai Zhenguo , Li Chenghong , Chen Yaolong , Gerotziafas Grigorios , Zhang Zhenlu , Wan Jun , Liu Peng , Elalamy Ismaïl , Wang Chen ,   On behalf of the Prevention Treatment of VTE Associated with COVID-19 Infection Consensus Statement Group
Published: May 2020

Coronavirus disease 2019 (COVID-19) has caused a global pandemic in just a few months, causing millions infected. Nearly 20% of COVID-19 patients present severe coagulation abnormalities, which may occur in almost all of the severe and critical ill COVID-19 cases. Concomitant venous thromboembolism (VTE), a potential cause of unexplained deaths, has been frequently reported in COVID-19 cases, but its management is still challenging due to the complexity between antithrombotic therapy and coagulation disorders. Based on frontline practical experience and comprehensive literature review, here a panel of experts and physicians from China and Europe developed an evidence and opinion-based consensus on the prophylaxis and management of VTE associated with COVID-19. This statement aims for clinicians treating COVID-19 and provides practical recommendations in detailed situations, for example, how to choose thromboprophylactic measures for patients with diverse severity of disease and bleeding risk, or which kind of anticoagulant should be prescribed. With limited experience on COVID19-associated VTE, this expert consensus statement should be helpful for clinicians worldwide with specific suggestions.
A Mid- to Long-Term Follow-Up Experience with a Specific Metal-on-Metal Total Hip Arthroplasty Design
Authors: Carulli Christian , Sani Giacomo , Matassi Fabrizio , Civinini Roberto , Innocenti Massimo
Published: May 2020

Purrpose Metal-on-metal (MoM) total hip arthroplasty (THA) has been a subject of recent discussion and concern due to the early failures caused by local and systemic adverse reactions related to specific designs. The aim of this study is to analyze the outcomes and survival rates of a single brand of MoM implants implanted in a consecutive series of patients at a single institution.

Methods Between 2007 and 2012, 116 (118 hips) patients were evaluated at a mean follow-up of 6.6 years after primary THA. The diagnosis leading to surgery was osteoarthritis (80 patients) and proximal femoral fracture (36 patients). A single design of THA was implanted. All patients were evaluated before surgery and postoperatively at 1, 3, 6, and 12 months by clinical scores and radiographic studies. The data analysis was made using Student's t-test.

Results The minimum follow-up was of 4 years, with a mean follow-up of 6.6 years. Two aseptic loosenings of the acetabular component were recorded (one per group), which were not associated with local or systemic complications related to metal ion release. Both were revised by an isolated acetabular cup substitution with metal-on-polyethylene couplings. Nonprogressive radiolucency lines < 2 mm in zone 2 were observed in other six patients around the acetabular component without clinical manifestation (four in the arthritis group and two in the fracture group). Postoperative Harris Hip Score and SF-36 (36-Item Short Form Survey) score improved in both groups.

Conclusion Despite several MoM implants showing early complications and failures, a specific MoM design may be associated with good clinical results at a mid- to long-term follow-up.

Level of Evidence This is a therapeutic case series, Level 4 study.
Medizintechnik und Hygiene: Die Infektionskette unterbrechen
Authors: Hagel Torben
Published: May 2020

Hygienevorschriften sind im Krankenhaus ehernes Gesetz. Das gilt für das eigene Personal ebenso wie für externe Service-Techniker. Wie auch ein modernes „Hygienic Design“ dazu beiträgt, die Infektionskette effizient zu unterbrechen, schildert Gastautor Torben Hagel, der beim Hersteller für Sicherheits- und Medizintechnik Dräger tätig ist.
Coronavirus: Krisenkommunikation in Zeiten einer Pandemie
Authors: Waschow Benjamin
Published: May 2020

Der Coranavirus hat das ganze Land in Alarmbereitschaft versetzt. Fakten und Emotionen verschwimmen. Für die Krisenkommunikationsteams in den Kliniken und Krankenhäuser wird Beruhigen und Aufklären zu einer der wichtigsten Aufgaben, und zwar nicht nur nach außen, sondern auch nach innen.
Can specific personality traits better explain EU attitudes?
Authors: Aichholzer Julian , Rammstedt Beatrice
Published: May 2020

Scholars trying to understand attitudes toward the European Union (EU) are increasingly interested in citizens’ basic predispositions, such as the “Big Five” personality traits. However, previous research on this particular relationship has failed to provide sound hypotheses and lacks consistent evidence. We propose that looking at specific facets of the Big Five offers a deeper understanding of the associations between personality predispositions, their measures, and EU attitudes. For this purpose, the 60-item Big Five Inventory-2, which explicitly measures Big Five domains and facets, was administered in a German population sample. We applied a variant of structural equation modeling and found that personality predispositions promoting communal and solidary behavior, cognitive elaboration, and a lower tendency to experience negative emotions predicted support for further European integration. Greater support of European integration might thus reflect, in part, basic psychological predispositions that facilitate adapting to the political, social, and cultural complexity posed by Europeanization. The study thus contributes to our understanding of deep-rooted patterns in thoughts and feelings that can shape citizens’ EU attitudes.
Understanding drivers when investing for impact: an experimental study
Authors: De Amicis Luisa , Binenti Silvia , Maciel Cardoso Felipe , Gracia-Lázaro Carlos , Sánchez Ángel , Moreno Yamir
Published: May 2020

In the last decade, a global interest in impact investing—whose goal is to generate social and environmental benefits alongside economic returns—has rapidly grown. In this context, this paper explores the socio-demographic characteristics of investors who choose impact investment options over traditional investments, and on the drivers promoting such choices. More specifically, the study consists of an experiment-based research in which 602 participants (non-experts and experts in the financial sector) took part in a multiple-choice game involving different investment scenarios and incentive conditions. The findings show that both expert investors and female participants are more likely to choose impact investment options and that the tendency to invest in social funds increases with age. Neither external and centrally planned incentives, such as fiscal incentives, nor the educational level of participants show a significant influence on investment choices. By contrast, information about the actual social impact achieved by funds plays a role in promoting socially oriented decisions. In this regard, visual aids appear to be an effective means of promoting impact investment. These findings may be of interest to policymakers, social campaigners and investment practitioners themselves when designing strategies for raising interest in impact investing or norms to strengthen a conducive and enabling environment for social entrepreneurship more broadly.
Developing a Citizen Social Science approach to understand urban stress and promote wellbeing in urban communities
Authors: Pykett Jessica , Chrisinger Benjamin , Kyriakou Kalliopi , Osborne Tess , Resch Bernd , Stathi Afroditi , Toth Eszter , Whittaker Anna C.
Published: May 2020

This paper sets out the future potential and challenges for developing an interdisciplinary, mixed-method Citizen Social Science approach to researching urban emotions. It focuses on urban stress, which is increasingly noted as a global mental health challenge facing both urbanised and rapidly urbanising societies. The paper reviews the existing use of mobile psychophysiological or biosensing within urban environments—as means of ‘capturing’ the urban geographies of emotions. Methodological reflections are included on primary research using biosensing in a study of workplace and commuter stress for university employees in Birmingham (UK) and Salzburg (Austria) for illustrative purposes. In comparing perspectives on the conceptualisation and measurement of urban stress from psychology, neuroscience and urban planning, the difficulties of defining scientific constructs within Citizen Science are discussed to set out the groundwork for fostering interdisciplinary dialogue. The novel methods, geo-located sensor technologies and data-driven approaches to researching urban stress now available to researchers pose a number of ethical, political and conceptual challenges around defining and measuring emotions, stress, human behaviour and urban space. They also raise issues of rigour, participation and social scientific interpretation. Introducing methods informed by more critical Citizen Social Science perspectives can temper overly individualised forms of data collection to establish more effective ways of addressing urban stress and promoting wellbeing in urban communities.
Interfacial cracks near an eccentric circular hole in piezoelectric bi-materials subjected to dynamic incident anti-plane shearing
Authors: An Ni , Song Tian-shu , Hou Gangling
Published: May 2020

Dynamic fracture analysis of piezoelectric materials with eccentric defects is an important criterion for the design of piezoelectric components. This work aims to suggest an effective method for the dynamic anti-plane shearing problem of piezoelectric bi-materials with permeable interfacial cracks near an eccentric circular hole. In the paper, Fredholm’s equations are solved via the Green’s function method and the coordinate transformation method. Based on conjunction and crack-deviation techniques, the dynamic stress intensity factors (DSIFs) at the outer and the inner tips of the left crack are expressed analytically. As cases, the effects of the eccentric distance, the piezoelectric parameters, the ratio of the crack length to the hole radius, and the dimensionless wave number of the incident wave are presented graphically.
Relation between circuit current and plasma current density in plasma discharges with dielectric media
Authors: Giuliani L. , Grondona D. , Minotti F.
Published: May 2020

The theoretical derivation of the relation between moving charges in the plasma and external circuit current was first established on a firm basis by Sato [J. Phys. D 13, L3 (1980)] for the case of a discharge with constant applied voltage between bare electrodes. The generalization to time varying applied voltages was established by Morrow and Sato [J. Phys. D 32, L20 (1999)], still considering bare electrodes. In the present work, we extend the latter derivation to include general devices with arbitrarily arranged linear dielectric media, and multiple electrodes with time dependent voltages, of interest, for instance, for a Dielectric Barrier Discharge (DBD). In particular, the present derivation determines a general, practical expression for the reactive term present in the Morrow and Sato formula. Using the expression derived, we show how in simple DBD geometries usual circuit approximations of the plasma discharge can be obtained and its validity was justified. Also, we consider the determination of the internal plasma current from the measurement of the external circuit current for a cylindrical DBD operated with helium at atmospheric pressure. Finally, we apply the theory to a three-electrode device in order to relate electric measurements to volume integrals on the plasma that were shown to be useful in order to quantify species production by electron impact.
Formation of ultracold 39K133Cs molecules via Feshbach optimized photoassociation
Authors: Hai Yang , Li Li-Hang , Li Jing-Lun , Wang Gao-Ren , Cong Shu-Lin
Published: May 2020

A Feshbach optimized photoassociation (FOPA) process for preparing ultracold excited-state 39K133Cs molecules is studied theoretically. Under the joint action of the magnetic field and short laser pulse, the colliding atoms in a superposition state composed of eight hyperfine components are converted into a molecule in the vibrational level of the excited state via two transition processes, the transition between singlet states and the transition between triplet states. The association efficiency can be significantly enhanced by taking advantage of Feshbach resonance. At different resonance positions, different hyperfine components of the superposition state dominate over the FOPA process, and the quantum interference displays different behaviors. Compared with the FOPA process only including a single hyperfine component, the quantum interference in the FOPA process containing all hyperfine components has a visible effect on the association efficiency.
Stress-altered aluminum powder dust combustion
Authors: Williams Alan , Shancita I. , Vaz Neil G. , Tran-Ngo Thao , Demko Andrew , Altman Igor , Hill Kevin J. , Tunega Daniel , Aquino Adelia J. A. , Pantoya Michelle L.
Published: May 2020

Aluminum powder was thermally stressed by annealing and quenching, then the powder was non-uniformly dispersed in air and examined for dust combustion behavior as a function of stress-altering conditions. An explosion chamber with a powder injector, spark gap igniter, pressure sensor, spectrometer, and high-speed camera was used for experimentation. Aluminum powder was annealed to 573 K, held for 15 min, and quenched at a rate of 200 K/min (pre-stressed, PS) or 900 K/min (super-quenched, SQ). The untreated (UN), PS, and SQ Al powders were injected into the chamber, and pressure, temperature, and flame spreading behavior were analysed. SQ Al powder exhibited lower pressurization rates than that of PS Al, which was also lower than that of UN Al. Surface modifications to the stress-altered powders may affect their dispersion and suspension in the air environment, which affects flame spreading and pressurization rate. Specifically, annealing powders caused the removal of surface hydration that had two effects: increased the surface energy of the particles (confirmed with density functional theory calculations) and decreased surface roughness (suggested from previous work revealing loss of a nanostructure at the surface with annealing). These two surface modifications may inhibit powder dispersion such that pressurization rate is reduced compared with UN Al powder.
Pressure-induced instability of the fergusonite phase of EuNbO4 studied by in situ Raman spectroscopy, x-ray diffraction, and photoluminescence spectroscopy
Authors: Garg Alka B. , Rao Rekha , Errandonea D. , Pellicer-Porres J. , Martinez-Garcia D. , Popescu C.
Published: May 2020

In this article, we present high-pressure experimental investigations on EuNbO4, an interesting technologically important material, using synchrotron based x-ray powder diffraction, Raman spectroscopy, and europium photoluminescence measurements up to 39.2, 31.6, and 32.4 GPa, respectively. All three techniques show the stability of the ambient monoclinic phase until 20 GPa. Beyond that, a pressure-induced structural phase transition takes place with the coexistence of two phases over a wide pressure range. The structure of the high-pressure phase has been determined as orthorhombic (space group: Imma) with a volume discontinuity of nearly 9% at the transition indicating the nature of transition to be first order. The high-pressure phase remains stable up to ∼40 GPa. The equation of state data for both phases have been determined, and the modulus of incompressibility indicates that the high-pressure phase with bulk modulus as 246(29) GPa is less compressible compared to the low-pressure phase having bulk modulus as 138(4) GPa. The transition involves a change in the coordination polyhedron around europium, increasing the coordination number from 8 in the fergusonite to 12 in the orthorhombic phase, while the coordination around niobium remains 4 in both the phases. All the 18 expected Raman modes in the fergusonite structure have been observed, and their variation as a function of pressure has been reported. The mode Grüneisen parameters for the observed Raman frequencies for monoclinic and orthorhombic phases have been determined. Europium photoluminescence spectra show drastic changes near the transition pressure, which point toward changes in the local environment around the europium ion.
Current-induced dynamical tilting of chiral domain walls in curved microwires
Authors: Finizio Simone , Wintz Sebastian , Mayr Sina , Huxtable Alexandra J. , Langer Manuel , Bailey Joe , Burnell Gavin , Marrows Christopher H. , Raabe Jörg
Published: May 2020

We report on the investigation of current-induced domain wall motion of Néel domain walls in perpendicularly magnetized microwires with curved geometries in the flow regime. The investigation was performed by time-resolved scanning transmission x-ray microscopy. In particular, we studied the dynamical tilting of the Néel domain walls, observing that an asymmetric behavior in the domain wall tilt appears upon an inversion of the polarity of the current pulse driving the motion, an effect not predicted by state-of-the-art theories and micromagnetic modeling.
Long-range asymptotics of exchange energy in the hydrogen molecule
Authors: Siłkowski Michał , Pachucki Krzysztof
Published: May 2020

The exchange energy, i.e., the splitting ΔE between gerade and ungerade states in the hydrogen molecule, has proven very difficult in numerical calculation at large internuclear distances R, while the known results are sparse and highly inaccurate. On the other hand, there are conflicting analytical results in the literature concerning its asymptotics. In this work, we develop a flexible and efficient numerical approach using explicitly correlated exponential functions and demonstrate highly accurate exchange energies for internuclear distances as large as 57.5 a.u. This approach may find further applications in calculations of inter-atomic interactions. In particular, our results support the asymptotics form ΔE ∼ R5/2e−2R, but with the leading coefficient being 2σ away from the analytically derived value.