bluuebunny/crossref_metadata_2025 huggingface dataset:
Testing the Influence of Changing Seawater Ca Concentration on Elements/Ca Ratios in Planktic Foraminifera: A Culture Experiment
Authors: Le Houedec Sandrine , Erez Jonathan , Rosenthal Yair
Published: February 2021

Element/Ca ratios in foraminifera shells are used to assess oceanic physical‐chemical properties (e.g., paleo‐temperature, paleo‐pH…). On geological time scales, these proxies may also depend on changes in the chemical composition of seawater. Here we investigate the effect of changing seawater calcium concentration on the Li/Ca, Mg/Ca, Sr/Ca, B/Ca, and Na/Ca ratios in low‐Mg calcite shells of the planktic foraminifer Globigerinella siphonifera. Specifically, we evaluate the possibility that Na/Ca in planktic foraminifera shells may serve as a proxy for Ca concentrations in the past ocean. Since Ca concentration in today's open ocean is largely conservative with relation to salinity, field calibrations are not possible. Therefore, we cultured the planktic foraminifer (G. siphonifera) collected from the Gulf of Eilat (Red Sea) in variable Casw (10.5–29 mmol/kg), at constant temperature (25°C) and under two salinities (37 and 40.6). When changing the Casw of the growth medium, the relationships between Mg/Ca and Na/Ca in the shells and their corresponding ratios in the seawater are best described by power functions implying a variable distribution coefficient function. For Sr/Ca and Li/Ca, the relations between the shells and the seawater are described by linear functions intersecting the origin implying their distribution coefficients are insensitive to changes in Casw. The results also confirm that foraminiferal B/Ca is not influenced by seawater Casw. We conclude that Na/Ca ratios in planktic foraminifera may serve as reliable proxy for Cenozoic ocean Ca, and that other El/Ca ratios may be used to determine their past concentrations relative to Ca.
Bookshelf Kinematics and the Effect of Dilatation on Fault Zone Inelastic Deformation: Examples From Optical Image Correlation Measurements of the 2019 Ridgecrest Earthquake Sequence
Authors: Milliner Christopher , Donnellan Andrea , Aati Saif , Avouac Jean‐Philippe , Zinke Robert , Dolan James F. , Wang Kang , Bürgmann Roland
Published: February 2021

The 2019 Ridgecrest earthquake sequence initiated on July 4th with a series of foreshocks, including an Mw 6.4 event, that culminated a day later with the Mw 7.1 mainshock and resulted in rupture of a set of cross‐faults. In this study, we use subpixel correlation of optical satellite imagery to measure the displacement, finite strain, and rotation of the near‐field coseismic deformation to understand the kinematics of strain release along the surface ruptures. We find the average off‐fault deformation along the mainshock rupture is 34% and is significantly higher along the foreshock rupture (56%), suggesting it is a less structurally developed fault system. Measurements of the 2D dilatational strain along the mainshock rupture show a dependency of the width of inelastic strain with the degree of fault extension and contraction, indicating wider fault zones under extension than under shear. Measurements of the vorticity along the main, dextral rupture show that conjugate sinistral faults are embedded within zones of large clockwise rotations caused by the transition of strain beyond the tips of dextral faults leading to bookshelf kinematics. These rotations and bookshelf slip can explain why faults of different shear senses do not intersect one another and the occurrence of pervasive and mechanically unfavorable cross‐faulting in this region. Understanding the causes for the variation of fault zone widths along surface ruptures has importance for reducing the epistemic uncertainty of probabilistic models of distributed rupture that will, in turn, provide more precise estimates of the hazard distributed rupture poses to nearby infrastructure.
Magma‐Fluid Interactions Beneath Akutan Volcano in the Aleutian Arc Based on the Results of Local Earthquake Tomography
Authors: Koulakov Ivan , Komzeleva Viktoria , Smirnov Sergey Z. , Bortnikova Svetlana B.
Published: February 2021

Akutan Island hosts a volcano considered as one of most active in the Aleutian Arc. We build a new tomography model including the 3D distributions of the Vp, Vs, and Vp/Vs ratio based on arrival time data from more than 4,000 local earthquakes recorded by 13 seismic stations. In this model, we reveal a columnar anomaly of high Vp, low Vs, and high Vp/Vs ratio with a top boundary at a depth of ∼6 km below sea level, which represents a steady conduit feeding the Akutan volcano. In the upper part of the tomographic model, the highly heterogeneous structures are associated with interactions of shallow magmatic sources, meteoric and magmatic fluids, as well as degassing. Beneath the summit area of Akutan, we observe a prominent anomaly of high Vp/Vs, which may represent a shallow magma reservoir directly responsible for recent eruption activity and ongoing gas emission through the summit fumarole. The other fumarole field at the eastern flank of the volcano appears to be associated with a seismically active zone of low Vp/Vs ratio at depths of 2–4 km below surface. These structures indicate different depths of magma degassing in these two areas, which may explain distinct geochemical features of emitted gases. Besides the prominent anomaly representing the shallow magma reservoir beneath the caldera and the active cone, we observe several areas with high Vp/Vs ratio, some of which are interpreted as shallow magma storage regions, and some as zones of meteoric water penetration.
Upper Ocean Stratification in the Eastern Pacific During the SPURS‐2 Field Campaign
Authors: Katsura S. , Sprintall J. , Bingham F. M.
Published: February 2021

The region between a shallow mixed layer and a deep isothermal layer resulting from salinity stratification is called a barrier layer (BL). Since BLs hinder the surface heat and momentum exchange with the ocean subsurface, they play an important role in air‐sea interaction. Synoptic features and formation of BLs and associated temperature inversions (TIs) in the Eastern Pacific Fresh Pool (EPFP) were investigated using shipboard observations. BLs and TIs were found in the high‐precipitation EPFP, a frontal transition zone (FTZ) and in the sea surface salinity (SSS) front during a 2016 boreal summer cruise. During a 2017 boreal autumn cruise, BLs and TIs were found from the southern part of the EPFP to the SSS front. The BLs in the SSS front and the FTZ were meridionally displaced from the precipitation maximum during both the 2016 and 2017 cruises. Freshening and cooling by tilting of both the isohalines and isotherms of the SSS front occurred via Ekman and geostrophic flow during both cruises, and also within the EPFP during 2016. The SSS front was a dominant contributor to the density gradient in the horizontal plane. A high dissolved oxygen content observed within BLs confirmed that the surface flow plays an important role in the BL and TI formation through the tilting process. Patchy distribution of freshening and cooling by tilting implies an intermittent BL and TI formation with short time scales.
Numerical Study of Near‐Surface Jet in the Atmospheric Surface Layer Over an Oceanic Temperature Front
Authors: Deng Bing‐Qing , Zhao Ming‐Xiang , Wang Qing , Shen Lian
Published: February 2021

The interaction between atmospheres and oceans plays an important role in the global climate. In a field experiment of atmospheric flows over the Gulf Stream, when the wind blew from the cold water to the warm water, we observed a near‐surface jet over the warm water. We then conducted direct numerical simulations and large‐eddy simulations of atmospheric turbulence in the vicinity of the front and captured the near‐surface jet in simulations for the first time. Analyses of the data obtained from the high‐resolution three‐dimensional simulations revealed the dominant generation mechanisms of the near‐surface jet, which are the strong vertical mixing by the enhanced streamwise rolls and the mean downward motion. Around the near‐surface jet, the magnitude of the negatively valued Richardson number significantly increases, indicating the dominance of buoyancy effects in the flow dynamics there. The development of the near‐surface jet suggests that the Monin‐Obukhov similarity theory (MOST) needs to be modified in representing marine atmospheric boundary layers over sea surface temperature fronts.
Impact of Land Surface Processes on a Record‐Breaking Rainfall Event on May 06–07, 2017, in Guangzhou, China
Authors: Gao Zhibo , Zhu Jiangshan , Guo Yan , Luo Neng , Fu Yuan , Wang Tiantian
Published: February 2021

A record‐breaking extreme rainfall event with a maximum rainfall amount over 24 h of 524.1 mm occurred in Guangzhou, China, on May 06–07, 2017. To study the impact of land surface processes on this extreme rainfall, two 21‐member convective‐permitting ensemble forecasts over South China were performed based on two land surface models (LSMs), Noah and Community Land Model (CLM), and 21 forecasting members of the Global Ensemble Forecast System (GEFS). The results showed that, in general, members using the Noah LSM could better simulate urban heat islands (UHIs) and urban convection than members using the CLM LSM in this case. By investigating the ensemble member that most resembled the observations, it was found that the high temperature center in the urban area caused a thermal low in the early stage. As the southerly winds strengthened, the low‐level convergence line continued moving northward and eventually triggered convection in the mountainous region. A sensitivity experiment showed that the impact of land surface heterogeneity on precipitation could be reflected on a finer scale, and heavy rainfall was very sensitive to the changes in small‐scale land surface forces, including terrain and land use. Slight variations in small‐scale land surface conditions caused great responses in the total precipitation, indicating that for the occurrence of such quasi‐stationary extreme rainfall, a subtle balance between different atmospheric and land surface factors may be required.
Persistent Provenance of South Asian Monsoon‐Induced Silicate Weathering Over the Past 27 Million Years
Authors: Ali Sajid , Hathorne Ed C. , Frank Martin
Published: February 2021

The development of the South Asian monsoon (SAM) and Himalaya‐Tibetan Plateau uplift were closely intertwined with some studies suggesting that uplift initiated the monsoon whereas others link tectonics with monsoon‐controlled exhumation. Silicate weathering controls atmospheric CO2 on geological timescales resulting in a large potential for monsoon strength and the Himalayan orogeny to influence global climate but detailed records of SAM‐induced weathering on million year (Myr) timescales are lacking. Here, we present radiogenic Sr, Nd, and Pb isotope compositions of clay minerals produced by silicate weathering and transported to the central Bay of Bengal. The radiogenic isotope data exhibit a relatively small range and demonstrate a remarkably consistent mixture of sources dominated by Himalayan rocks and the Indo‐Burman ranges, which consist of sediments derived from the Himalayas. This suggests that the spatial pattern of regional weathering, which today is highest in the regions of strongest monsoon rains, has persisted in a similar form for the last 27 Myrs. A pronounced increase in primary clay mineral abundance (from 9% to 22%) coincident with global cooling 13.9 Myrs ago points to a shift in the weathering regime given that the clay provenance did not change dramatically. Relatively weaker chemical weathering intensity during the mid and late Miocene cooling suggests increased aridity and changes in the large scale atmospheric circulation in the SAM domain. The establishment of the dry winter monsoon season during the mid and late Miocene may have caused this shift in the weathering regime and can reconcile much of the contrasting evidence for SAM initiation.
Fluorescent assay for quantitative analysis of trimethylamineN-oxide
Authors: Zhang Wen , Sun Jiao , Wang Fang , Liu Jiang , Han Ying , Jiang Miao , Tang Dongqi
Published: February 2021

TrimethylamineN-oxide (TMAO), a gut microbial metabolite involved in cardiovascular and kidney diseases, has great potential as a biomarker, thus making TMAO quantification of great significance.
Potassium-ion batteries: outlook on present and future technologies
Authors: Min Xin , Xiao Jun , Fang Minghao , Wang Wei (Alex) , Zhao Yajing , Liu Yangai , Abdelkader Amr. M. , Xi Kai , Kumar R. Vasant , Huang Zhaohui
Published: February 2021

The limited resources and uneven distribution of lithium stimulate strong motivation to develop new rechargeable potassium-ion batteries that use alternative charge carriers.
Reply to the ‘Comment on “Giant pyroelectric energy harvesting and a negative electrocaloric effect in multilayered nanostructures”’ by X. Chen, V. Shvartsman, D. C. Lupascu and Q. M. Zhang, Energy Environ. Sci., 2021, DOI: 10.1039/D0EE02548H
Authors: Vats Gaurav , Kumar Ashok , Bowen Chris R. , Ortega Nora , Katiyar Ram S.
Published: February 2021

A detailed explanation of the calculations for the electrocaloric effect (ECE) performance of thin-film heterostructures for motivating the scientific community to carry out experiments for validation.
Stereodivergent Pd/Cu catalysis: asymmetric alkylation of racemic symmetrical 1,3-diphenyl allyl acetates
Authors: Zhao Ling , Li Guanlin , He Rui , Liu Penglin , Wang Feijun , Huo Xiaohong , Zhao Min , Zhang Wanbin
Published: February 2021

A stereodivergent Pd/Cu catalyst system was developed, which was successfully applied to the asymmetric allylic alkylation of symmetrical 1,3-disubstituted allyl acetates with prochiral imino esters in a fully stereodivergent manner.
Periodic arrays of plasmonic crossed-bowtie nanostructures interspaced with plasmonic nanocrosses for highly sensitive LSPR based chemical and biological sensing
Authors: Das Abhijit , Kumar Kamal , Dhawan Anuj
Published: February 2021

Plasmonic nanostructure with very high localized LSPR sensitivity around 1310 nm and 1550 nm communication wavelengths.
Photosensitizer-loaded hydrogels for photodynamic inactivation of multirestistant bacteria in wounds
Authors: Glass Sarah , Kühnert Mathias , Lippmann Norman , Zimmer Joanne , Werdehausen Robert , Abel Bernd , Eulenburg Volker , Schulze Agnes
Published: February 2021

Photodynamic treatment is a promising tool for the therapy of multidrug-resistant bacteria.
Cleavable and tunable cysteine-specific arylation modification with aryl thioethers
Authors: Li Jian , Deng Jun-Jie , Yin Zhibin , Hu Qi-Long , Ge Yang , Song Zhendong , Zhang Ying , Chan Albert S. C. , Li Huilin , Xiong Xiao-Feng
Published: February 2021

A cleavable and tunable covalent modification approach for cysteine by aryl thioethers via a SNAr approach was developed. The highly efficient and selective bioconjugation reactions can proceed under the mild and biocompatible conditions.
Symmetry-related residues as promising hotspots for the evolution of de novo oligomeric enzymes
Authors: Yu Jaeseung , Yang Jinsol , Seok Chaok , Song Woon Ju
Published: February 2021

Symmetry-related residues located at the rotational axes can be promising hotspots for the evolution of de novo oligomeric enzymes even though they are distantly located from the active site pocket.
Essential role of quantum science and nanoscience in antiviral strategies for COVID-19
Authors: Zare Mina , Sillanpää Mika , Ramakrishna Seeram
Published: February 2021

The severe acute respiratory syndrome coronavirus (SARS-CoV-2) that caused the COVID-19 disease pandemic since December 2019 highlights the importance of developing efficient antiviral strategies to prevent and treat viral infection.
Novel handover scheme for indoor VLC systems
Authors: Younus Safwan Hafeedh , Al‐Hameed Aubida A. , Hussein Ahmed Taha
Published: February 2021

Managing mobility in visible light communication systems is one of the main encounters that requires to be tackled. In this paper, we propose subcarrier multiplexing tones as control signals for handover in visible light communication systems. These control tone signals are unmodulated signals, and each light unit is given a unique unmodulated control signal. One light unit is used to send the data to the user, which is the best light unit. At a receiver side, band pass filters are used to separate subcarrier multiplexing tones. This enables receiver to connect with all light units via subcarrier multiplexing tones. The carrier to noise ratio of each control tone signal is estimated at the receiver, which leads to make the receiver connects with the light unit that offers the best connection during its mobility.
Novel grid‐forming control of PMSG‐based wind turbine for integrating weak AC grid without sacrificing maximum power point tracking
Authors: Li Yujun , Yuan Xiaotian , Li Jiapeng , Xiao Huangqing , Xu Zhao , Du Zhengchun
Published: February 2021

Traditional permanent magnet synchronous generator (PMSG)‐based wind turbine (WT) normally utilises phase lock loop (PLL) for obtaining accurate phase angle of AC grid to make sure of maximum power point tracking (MPPT). However, a weak AC system with a low short circuit ratio (SCR) and high control bandwidth of PLL might have impaired effects on the stability of the system. To overcome these, a novel power synchronous control of PMSG‐based WT with grid forming ability of PMSG for integrating very weak AC system is first proposed in this study. Grid‐side converter (GSC) of PMSG emulates the inertia response of synchronous generator (SG) by artificially coupling the DC‐link voltage with the grid frequency based on the certain droop property, while the converter voltage magnitude is regulated according to DC‐link voltage deviation by controlling the modulation index of GSC. This novel scheme can realise the grid synchronisation without PLL by mimicking the natural characteristic of SG. Small‐signal analysis of the proposed scheme indicates the DC‐link capacitor energy can be exerted for system inertia support during system disturbances, while the system damping can be provided by spontaneously alternating converter voltage magnitude. More importantly, MPPT property of PMSG is not compromised while providing inertia and damping for the system, and the related inertia and damping coefficient of WT with the proposed control can be easily tuned for satisfying the system requirement. Non‐linear simulations of one PMSG connected with one large SG considering a sudden change of active power reference and variable wind speeds have been studied to verify the effectiveness of the proposed grid‐forming control.
Synchronisation of second‐order stochastic complex dynamical networks via intermittent pinning discrete observations control and their applications
Authors: Wu Yongbao , Guo Zhengrui , Li Wenxue , Feng Jiqiang
Published: February 2021

In this study, the exponential synchronisation of second‐order stochastic complex dynamical networks (SOSCDNs) is considered. A novel control called periodically intermittent pinning discrete observations control is proposed, which is based on discrete‐time state observations instead of continuous‐time state observations during the control time. To the authors' knowledge, the above control strategy has rarely been investigated in previous researches. Compared with the existing literature, there are no restrictions on the network topology structure in this study. Furthermore, by employing the Lyapunov method, stochastic analysis techniques, and matrix theory, a synchronisation criterion and a corollary about the exponential synchronisation of the SOSCDNs are presented. In particular, when the duration between two consecutive observations tends to zero, periodically intermittent pinning discrete observations control degenerates into periodically intermittent pinning control, and relevant corollaries are also derived. Finally, they applied theoretical results to single‐link robot arm systems and oscillator systems. Meanwhile, the numerical simulations are performed to demonstrate the effectiveness of their results.
Distributed adaptive consensus tracking control for non‐linear multi‐agent systems with time‐varying delays
Authors: Zamani Najmeh , Askari Javad , Kamali Marzieh , Aghdam Amir
Published: February 2021

In this study, a novel distributed adaptive controller is provided for consensus control of high‐order non‐linear multi‐agent systems with unknown time‐varying delays. The system is subject to uncertain disturbances, and the agents' dynamics are not known. Unlike the existing literature, the proposed method does not require time‐delay terms in system dynamics to be bounded. A neural network is used to model the unknown non‐linear dynamics. Then, despite the destabilising effect of the unknown delays, some adaptive rules based on the dynamic surface control are designed to achieve the consensus objective. The semi‐global uniform boundedness of the resultant closed‐loop signals and the convergence of the tracking errors to a neighbourhood of the origin are shown mathematically. Simulations verify the effectiveness of the results.
Adaptive fuzzy fault‐tolerant control for non‐linear systems under actuator and sensor faults: the practical fixed‐time stability
Authors: Yang Yekai , Niu Yugang , Zhang Zhina
Published: February 2021

This study investigates the adaptive fault‐tolerate control for strict‐feedback non‐linear system, in which actuator and sensor faults may happen simultaneously. Moreover, the additive and multiplicative faults are considered, which cover the bias, drift, loss of accuracy, and loss of effectiveness faults. Under the multiple sensor faults, a modified backstepping technique involving in the faulted states is proposed by utilising the fuzzy approximation to the unknown non‐linear functions. Later, the adaptive fuzzy fault‐tolerant control strategy is designed to ensure the practical fixed‐time stability of the closed‐loop system. Meanwhile, the convergence time is independent of the initial states of the system, and the control performance can be ensured for arbitrary bounded initial states in this study. Finally, the Buck converter circuit is employed to demonstrate the effectiveness of the proposed fault‐tolerant control scheme.
Parametric method to design dynamic compensator for descriptor high‐order quasi‐linear systems
Authors: Gu Da‐Ke , Zhang Da‐Wei , Liu Yin‐Dong
Published: February 2021

This study investigates a parametric method to design a dynamic compensator for descriptor high‐order quasi‐linear (DHQ) systems. Utilising the solution to generalised high‐order Sylvester equations, a more unified parametric form of the dynamic compensator is developed to improve the control effects. Meanwhile, normalisation design by using the dynamic compensator is also considered for DHQ systems such that the closed‐loop regularity can be maintained easily and effectively. Whether the closed‐loop form is singular or not, it has an expected eigenstructure. Finally, an example is provided to verify the parametric method is feasible and reliable.
Performance improvement of DFIG‐based wind farms using NARMA‐L2 controlled bridge‐type flux coupling non‐superconducting fault current limiter
Authors: Islam Md. Rashidul , Hasan Jakir , Hasan Md. Mahmudul , Huda Md. Najmul , Hossain Sadi Mohammad Ashraf , AbuHussein Ahmed
Published: February 2021

Doubly‐fed induction generators (DFIGs) have drawn prominent interest in the field of wind power generation, but they are vulnerable to grid faults. Grid codes mandate DFIGs to employ a sort of fault ride‐through (FRT) technique during faults. Fault current limiters (FCLs) always help to augment the FRT capability of DFIGs and a non‐linear controller boosts their performances. In this study, a non‐linear auto‐regressive moving average‐L2 (NARMA‐L2) controller‐based bridge‐type flux coupling non‐superconducting FCL (BFC‐NSFCL) is proposed to enhance the FRT capability of the wind farm. The authors analysed the performance of the proposed NARMA‐L2‐based BFC‐NSFCL (NL2‐BFC‐NSFCL) against that of the conventionally used series dynamic braking resistor (SDBR), bridge‐type FCL (BFCL), and proportional–integral (PI) controller‐based BFC‐NSFCL (PI‐BFC‐NSFCL). They tested the performance of the NL2‐BFC‐NSFCL through multiple temporary and permanent fault scenarios and carried out the mathematical and graphical analysis in MATLAB/Simulink platform. They found that the proposed NL2‐BFC‐NSFCL's performance surpasses the performances of the SDBR, the BFCL, and the PI‐BFC‐NSFCL. Moreover, the NL2‐BFC‐NSFCL has faster system recovery capability after the occurrence of any fault than other competitors.
Design and analysis of Levenberg–Marquardt‐based adaptive SOGI
Authors: Pandey Amarendra , Singh Alka
Published: February 2021

This study presents the design and analysis of an adaptive second‐order generalised integrator (SOGI) technique for controlling voltage source inverter in a three‐phase three‐wire distribution system. The function of the proposed shunt active power filter involves compensation of reactive power for power factor correction, harmonic elimination, load balancing, voltage regulation under non‐linear load condition. In this study, an effective approach for load compensation is proposed by designing an adaptive SOGI trained using Levenberg–Marquardt technique and compared with conventional techniques which ensure smooth operation under normal and distorted grid condition. An experimental setup is developed and its performance is analysed during different loading conditions. The experimental results are in line with the expected simulation results. Experimental and simulation results are verified and analysed using Bode plot.
Design and HIL implementation of a new robust fractional sliding mode control of microgrids
Authors: Delavari Hadi , Naderian Sina
Published: February 2021

Microgrid inverters in the presence of faults, unavoidable modelling uncertainties, disturbance and harmonic current resulting from nonlinear loads should have small steady state tracking error, small THD and high robustness hence this subject has turned one of the motivations of this investigation. To achieve the stated goals, fractional adaptive sliding mode controller (FASMC) is proposed in this paper. The proposed controller increases the robustness, flexibility and degree of freedom. As far as in practice it is not easy to define the bounds of disturbances and guarantee the system stability, hence in next step, to overcome this challenge the adaptation laws are suggested. Then for the problem of determining the controller parameters, Particle Swarm Optimization (PSO) algorithm is used. The performance of the proposed technique is investigated for an islanded microgrid under different disturbances, also to verify the advantages of the proposed controller, the results are compared with other controllers. Finally, the proposed controller and PID controller are implemented experimentally on Arduino mega 2560 microcontroller.
Compensation voltage moduli comparison‐based wide‐area protection algorithm independent of data synchronism and integrity
Authors: Lin Xiangning , Ma Shumin , Jin Neng , Tong Ning , Chen Le , Li Zhengtian , Rong Zirui , Zhang Peifu
Published: February 2021

Secondary direct‐current loss within a substation is a severe event. In China, each line protection device is generally powered by one set of secondary direct current (DC) power system within a substation of 110 kV voltage level. In this case, the line protection devices will be immediately taken out of service when the secondary DC is lost, and the lines protected by them will lose their corresponding protections. Once a fault occurs on the line, only the remote back‐up protection can be relied on to isolate the fault, which expands the fault influence and increases its clearance time. To handle the above problem, a novel wide‐area protection algorithm based on compensation voltage moduli comparison is proposed, which is independent of multi‐terminal data synchronism. Then, a comprehensive protection strategy composed of the proposed protection algorithm and the original local distances protection is proposed. The results from a power systems computer aided design/electromagnetic transients including DC (PSCAD/EMTDC)‐based simulation verify that the proposed protection algorithm has higher sensitivity. The comprehensive protection strategy could cope with most line faults effectively, even if only partial data are available, the selectivity and speed of which are better than that of distance protections.
Comprehensive review on hierarchical control of cyber‐physical microgrid system
Authors: Shrivastava Sonam , Subudhi Bidyadhar
Published: February 2021

A microgrid (MG) is a cyber‐physical system that facilitates integration of several distributed renewable energy resources. In the last decade, several efforts were made to standardise the framework of a cyber‐physical MG network and its control structure. In this perspective, various studies discussing the different control techniques are reported in the literature. However, a comprehensive and systematic review of a cyber‐physical MG is discussed rarely. In this study, a comprehensive review of a MG architecture and hierarchical control structure in both islanded and grid‐connected modes are presented. The hierarchical control of the MG includes primary, secondary, and tertiary control. Recent studies provide significant opportunities in dividing the control task among various layers resulting in a distributed framework. This study analyses the cyber and physical networks separately while discussing the primary, centralised, and distributed secondary control levels with their merits, demerits, and typical applications. A Venn diagram analysis is also presented that clearly distinguishes the primary control scheme in different research sub‐areas. Furthermore, the MG communication structure, protocols, design, constraints, and cyber security are also reviewed systematically. Finally, future trends are summarised based on the state‐of‐the‐art MG research.
Ensemble empirical mode decomposition‐based differential protection scheme for islanded and grid‐tied AC microgrid
Authors: Anand Abhisekh , Affijulla Shaik
Published: February 2021

This study presents a differential protection scheme based on ensemble empirical mode decomposition (EEMD) for AC microgrid. The fault current level is significantly lower during the islanded operation of a microgrid, which leads to the malfunction of the traditional over‐current protection scheme. The proposed differential protection scheme uses the spectral differential energy of the first intrinsic mode function extracted from the decomposition of the current signal using EEMD for effective fault detection in the AC microgrid. The proposed EEMD‐based differential protection scheme is validated on 10 bus and modified IEEE 34‐bus AC microgrid test systems during various shunt faults. Moreover, the performance of the proposed EEMD‐based differential protection scheme is evaluated under high fault impedance scenarios. The simulation results reveal that the proposed differential protection scheme can effectively detect the faulty line in an AC microgrid during seamless islanded and grid‐tied operations.
Novel power flow analysis method based on impedance matching for UPQC with grid voltage fluctuations and unbalanced loads
Authors: Zhao Xiaojun , Zhang Chunjiang , Guo Xiaoqiang , Chai Xiuhui , Jia Dongqiang , Shi Changli , Wei Tongzhen
Published: February 2021

A new perspective of impedance matching is proposed to study the power flow operation of the three‐phase four‐wire (3P4W) unified power quality conditioner (UPQC) system. Specifically, the UPQC system is equivalent to an adjustable impedance network, when external conditions change, such as grid voltage sag/swell and unbalanced loads, the node impedances in the network will be dynamically matched. On the one hand, the three nodes of the series converter (SC) will be matched as positive or negative impedances with the change of grid voltages, which means that the SC operates in a rectifier or inverter state to absorb or transmit the energy. On the other hand, to compensate the unbalanced load currents, the three nodes of the parallel converter (PC) will be matched as positive and negative impedances at the same time, which means that the PC operates in both rectifier and inverter state to absorb and transmit the energy. After matching the node impedances, the system's output node impedances are equal to the load impedances, thus achieving the power balance of the whole system. Experimental results of the power flow and impedance matching from a laboratory‐scale prototype hardware are presented to evaluate the correctness of the impedance analysis.
Explicit discrete modelling of bidirectional dual active bridge dc–dc converter using multi‐time scale mixed system model
Authors: Iqbal Mohammad Tauquir , Maswood Ali I. , Dehghani Tafti Hossein , Tariq Mohd , Bingchen Zhong
Published: February 2021

Dual active bridge (DAB) is one of the most popular high power isolated bidirectional dc–dc converter. It offers high power density, a low number of passive components, high efficiency. It is essential to model the converter so that it can be used in applications such as solid‐state transformer, micro‐grids, and dc distribution systems. Moreover, modelling a system is used to design inductor, select the switches, and controller design. The advantage of the discrete‐time models is that they explicitly describe state trajectories in all sub‐intervals of converter operation, meaning they are capable of providing exact solutions for ac state variables. This study proposes time scaling mixed system model of the DAB. The proposed method provides explicit solutions of the large and small signal, which can be used to study the steady‐state and transient nature of the converter. The experimental results validate the proposed model with high accuracy in the open and closed‐loop operation.
High step‐up DC–DC converter based on coupled‐inductor for renewable energy systems
Authors: Ghaffarpour Sadighi Hossein , Afjei Seyed Ebrahim , Salemnia Ahmad
Published: February 2021

The present study introduced a novel soft‐switched high step‐up DC–DC converter based on coupled inductors. The higher boost‐factor is achieved relying on previous topologies by adjusting the turns ratio of the coupled inductors. Thus, the proposed converter provides a higher voltage gain with lower duty ratios. Two active clamp circuits are employed to clamp the voltage spikes resulted from parasitic inductances. This active clamp circuit provides zero‐voltage switching turn‐on operations and zero‐current switching turn on/off operations for active switches and power diodes, respectively. In addition, the equivalent leakage inductance of the coupled inductors is placed in series with the power diodes, which significantly alleviates the reverse‐recovery problem of diodes. The other features of the proposed topology include fewer components, low cost, small input current ripple, and the low voltage stress on power switches. Low voltage stress allows choosing a lower voltage rating metal–oxide–semiconductor field‐effect transistor, which directly reduces the cost. The experimental results evaluated the performance of the proposed topology. For this purpose, a 48 V/380 V/500 W laboratory prototype was built and tested, and the results confirmed the performance of the presented converter.
Simple low‐cost ZVS bidirectional forward converter with phase shift control and voltage matching for low power applications
Authors: Bahrami Hamid , Ghavideljaliseh Mehdi , Adib Ehsan
Published: February 2021

In this study, a new zero‐voltage switching (ZVS) output inductor‐less bidirectional forward (OILBF) converter is presented. The OILBF has two diodes less than the conventional forward converter and is convenient for low‐power bidirectional applications. Moreover, the OILBF converter uses the leakage inductance of transformer as the forward inductor. In the proposed OILBF, two capacitors paralleled with main switches realise ZVS conditions for main switches in both directions without any auxiliary switches. Also, the reset of the converter transformer is done without any additional circuit. The proposed converter structure due to employing simultaneously OILBF topology with the simple auxiliary soft‐switching circuit is simple and low cost. The ZVS soft‐switching range is from light load to full load which enhances the converter efficiency. Phase shift is applied with the proposed converter. The proposed converter is completely analysed and its design approach is considered. Finally, an experimental prototype is implemented to verify theoretical results.
Wide CCM region modulation technique with low current ripples for impedance source inverters
Authors: Abbasi Milad , Mardaneh Mohammad , Ayad Ayman , Kennel Ralph
Published: February 2021

This study proposes a new pulse‐width modulation (PWM) technique for impedance source inverters, namely non‐tangential maximum boost control (NTMBC) technique at which the voltage gain of inverter in high‐modulation indices is higher than those of three traditional carrier‐based sine wave PWM techniques (simple boost control, maximum boost control (MBC), maximum constant boost control). In the conventional MBC technique, the duration of shoot‐through (ST) states varies from one switching cycle to another. This drawback results in a greater low‐frequency output frequency‐dependent ripple on both inductor current and voltage of the capacitor. Using the proposed NTMBC the ST duty cycle ratio can be kept approximately constant at each switching cycle. Consequently, in comparison with MBC, the peak value of inductor current, as well as its ripple, is noticeably low in the proposed NTMBC. Additionally, the source and ST currents in the proposed NTMBC method are less than those in the conventional MBC method. Using the proposed ST states does not have a considerable effect on total harmonic distortion (THD) of output waveforms and the THD in the NTMBC method is in a reasonable range. The proposed NTMBC method is validated using an experimental set‐up.
High step‐up interleaved zero‐voltage transition DC–DC converter with coupled inductors
Authors: Mirzaei Amin , Rezvanyvardom Mahdi , Mekhilef Saad
Published: February 2021

A high step‐up DC–DC converter which is applied to a voltage lift capacitor and coupled inductors to increase the voltage gain is proposed in this study. Moreover, the interleaved structure is applied in the converter to decrease the input ripple current. Besides, the voltage stress across the main and auxiliary switches is low. Furthermore, all switches and diodes have the soft‐switching condition by using an active clamp auxiliary cell. Consequently, the proposed converter has a high efficiency which is ideal for photovoltaic applications. Energy stored in the coupled inductors is transferred to the voltage lift capacitors and then transmitted to the output. Therefore, no voltage spikes caused by leakage inductors are created on the main switches. The converter operates in continuous current mode and its control remains in pulse width modulation. A 210 W laboratory prototype of the converter with 40 V input voltage and 420 V output voltage under 100 kHz switching frequency is constructed and experimental results confirm the theoretical analysis. Low voltage stress, low input ripple current and high efficiency (96.5%) show the superiority in the operation of the proposed converter in comparison with other similar structures.
Charging equaliser based on wireless power transfer for electric scooters
Authors: Liu Lizhou , Lu Yuanfang , Xu Bing , Xiong Liang , Chen Yang , Zhou Wei , Mai Ruikun , He Zhengyou
Published: February 2021

It is more convenient and safer to employ wireless power transfer (WPT) systems to charge the battery pack of electric scooters (ESs) than conventional plug‐in systems. A charging equaliser suitable for ESs is proposed to achieve constant current (CC) output without communication link between the transmitter side and the receiver side. The full‐bridge rectifier and select switches utilised at the receiver side are employed to be operated once to change from the balancing mode to charging modes. The characteristics of the load‐independent current output in the CC mode are achieved by properly selecting the parameters of the circuit so that no sophisticated control strategies are required to regulate the output as per the charging profile. The experimental results show that when the voltage of battery pack is charged at 32 or 4.2 V, the current is 1.02 or 1.12 A, respectively. Therefore, the proposed system can be considered as a CC system.
Effects of jet angle on harmonic structure of sound radiating from the flute
Authors: Onogi Kimie , Yokoyama Hiroshi , Iida Akiyoshi
Published: February 2021

For an isolated flute head joint, the effects of jet angle on harmonic structure of a single note are investigated within the practical range for human players. The mechanisms of these effects are discussed on the basis of both the radiated sound and the flow field measured with a hot-wire anemometer. The blowing parameters, viz., jet angle (angle between jet direction and window), jet offset (relative height of jet direction from the edge), lip-to-edge distance, and flow rate, were varied independently by using an artificial blowing device based on measured conditions for a human player, where the jet direction is defined as that measured without the head joint. The radiated sound revealed that jet angle varied the differential sound pressure level of the second to third harmonic (ΔSPL) less than jet offset, however, as much as flow rate and more than lip-to-edge distance. The spatial distribution of jet fluctuation center showed that, with increasing jet angle (the jet direction approaches vertical to the window), the jet deflected more inside, so that the actual jet offset was estimated to be further inside. The variation of ∆SPL with jet angle seems to be caused mainly by this shift in the actual jet offset.
Lateral variations of pressure-temperature evolution in non-cylindrical orogens and 3-D subduction dynamics: the Betic-Rif Cordillera example
Authors: Bessière Eloïse , Jolivet Laurent , Augier Romain , Scaillet Stéphane , Précigout Jacques , Azañón José-Miguel , Crespo-Blanc Ana , Masini Emmanuel , Do Couto Damien
Published: February 2021

The long-term Pressure-Temperature-time-deformation (P-T-t-d) evolution of the internal zones of orogens results from complex interactions between the subducting lithosphere, the overriding plate and the intervening asthenosphere. 2-D numerical models successfully reproduce naturalP-T-t-dpaths, but most orogens are non-cylindrical and the situation is far more complex due to 3-D pre-orogenic inheritance and 3-D subduction dynamics. The Mediterranean orogens are intrinsically non-cylindrical. Their 3-D geometry results from the complex shape of the Eurasian and African margins before convergence and from the dynamics of slab retreat and tearing leading to strongly arcuate belts. More than many other segments, the Betic-Rif belt is archetypal of this behavior. A synthesis of the tectonometamorphic evolution of the Internal Zones, also based on recent findings by our group in the framework of the Orogen Project (Alboran domain, including the Alpujárride-Sebtide and Nevado-Filábride complexes) shows the relations in space and time between tectonic andP-Tevolutions. The reinterpretation of the contact between peridotite massifs and Mesozoic sediments as an extensional detachment leads to a discussion of the geodynamic setting and timing of mantle exhumation. Based on new40Ar/39Ar ages in the Alpujárride-Sebtide complex and a discussion of published ages in the Nevado-Filábride complex, we conclude that the age of the HP-LTmetamorphism is Eocene in all complexes. A first-order observation is the contrast between the well-preserved Eocene HP-LTblueschists-facies rocks of the eastern Alpujárride-Sebtide Complex and the younger HT-LPconditions reaching partial melting recorded in the Western Alpujárride. We propose a model where the large longitudinal variations in theP-Tevolution are mainly due to (i) differences in the timing of subduction and exhumation, (ii) the nature of the subducting lithosphere and (iii) a major change in subduction dynamics at ∼20 Ma associated with a slab-tearing event. The clustering of radiometric ages obtained with different methods around 20 Ma results from a regional exhumation episode coeval with slab tearing, westward migration of the trench, back-arc extension and thrusting of the whole orogen onto the African and Iberian margins.
A comment on “Morphologic and genetic characterization of Corsican and Sardinian trout with comments onSalmotaxonomy” by Dellinget al.(2020): protected Tyrrhenian trouts must be named
Authors: Denys Gaël P.J.
Published: February 2021

The introduction of the use of molecular data has caused debates on the taxonomy of Corsican and Sardinian trouts, also referred to as Tyrrhenian trouts (i.e.Salmo trutta,Salmo macrostigma,Salmo cettii). A recent study by Dellinget al.(2020) (Morphologic and genetic characterization of Corsican and Sardinian trout with comments onSalmotaxonomy.Knowl Manage Aquat Ecosyst421: 21) introduces important evidence regarding the taxonomy of these populations. However, their subsequent denomination asSalmosp., that is, an undefined taxon, could have serious consequences on their future conservation management plans. Considering their threatened status, the Tyrrhenian trouts should be referred to asSalmo truttauntil the ongoing taxonomic uncertainty can be unambiguously resolved. These populations must then be treated as an Evolutionary Significant Unit (ESU) or as an Operational Conservation Unit (OCU) for further conservation managements plans, as already done for other Mediterranean trout lineages.
Mehr Zeit für Patienten
Authors: Schwoerer Barbara , Schuster Julia
Published: February 2021

Um aktuellen und zukünftigen Entwicklungen des deutschen Gesundheitswesens zu begegnen, hat das KfH Kuratorium für Dialyse und Nierentransplantation e. V. als größter gemeinnütziger Dialyseanbieter in Deutschland das Programm „Mehr Zeit für Patienten“ entwickelt. Es hat die Intention, die Mitarbeiter und Mitarbeiterinnen dazu zu befähigen, dass sie eigenverantwortlich ihre Arbeitsplätze gut organisieren und die Arbeitsabläufe innerhalb ihres Teams sowie die Zusammenarbeit mit anderen Bereichen verbessern. Hierbei wird das Ziel verfolgt, die Veränderung mit der Kraft und den Ideen aller zu gestalten, um am Ende mehr Zeit für die originäre Aufgabe der Pflege – die unmittelbare Arbeit am Patienten – zu erhalten. In einer modularen Weiterbildung wird den Teilnehmern des Programms zunächst die hierfür notwendige Methoden- und Moderationskompetenz vermittelt. Erste Ergebnisse zeigen: Mit der Einführung des Systems verbessern sich Zusammenarbeit und Kommunikation im Team. Wichtig für eine erfolgreiche Umsetzung ist es, zu Beginn kleine Schritte in Richtung der kontinuierlichen Verbesserung zu gehen und diese nachhaltig auszubauen. Der Erfolg wird sich dann einstellen, wenn die Führungskräfte es verstehen, jeden im Team zu motivieren und für das Thema zu begeistern.
Placebo-Effekte bei chronischen Schmerzen: Forschungsstand und
klinische Anwendung
Authors: Müller Maike , Bräscher Anne-Kathrin
Published: February 2021

Spielte der Placebo-Effekt in der Vergangenheit vorwiegend eine (eher
unliebsame) Rolle bei randomisierten kontrollierten Studien, so treten nun
vermehrt die mit dem Placebo-Effekt verbundenen Chancen und
Möglichkeiten in den Vordergrund. Auch Patienten mit chronischen
Schmerzen scheinen durch den Placebo-Effekt von einer wirksameren Behandlung
profitieren zu können: durch eine gezielte Beeinflussung des
therapeutischen Kontexts.
Fetale Rhabdomyome: Hinweis auf tuberöse Sklerose
Authors: Franz Cordula , Ritter Monica , Germund-Maiwald Ingo , Krämer Nils , Enzensberger Christian
Published: February 2021

Die Erstvorstellung der 30-jährigen IG/0P erfolgte mit 26+1 Schwangerschaftswochen (SSW) zur weiteren Betreuung nach extern erfolgter Amniozentese und bereits molekulargenetisch gesicherter fetaler Tuberöser Sklerose (Mutation im TSC2-Gen).