bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Rate of Coastal Temperature Rise Adjacent to a Warming Western Boundary Current is Nonuniform with Latitude
Authors: Malan Neil , Roughan Moninya , Kerry Colette 
Published: December 2020

AbstractWestern boundary currents (WBCs) have intensified and become more eddying in recent decades due to the spin‐up of the ocean gyres, resulting in warmer open ocean temperatures. However, relatively little is known of how WBC intensification will affect temperatures in adjacent continental shelf waters where societal impact is greatest. We use the well‐observed East Australian Current (EAC) to investigate WBC warming impacts on shelf waters and show that temperature increases are nonuniform in shelf waters along the latitudinal extent of the EAC. Shelf waters poleward of 32°S are warming more than twice as fast as those equatorward of 32°S. We show that nonuniform shelf temperature trends are driven by an increase in lateral heat advection poleward of the WBC separation, along Australia's most populous coastline. The large‐scale nature of the process indicates that this is applicable to WBCs broadly, with far‐reaching biological implications.
Asymmetric Structure of Uranus' Magnetopause Controlled by IMF and Planetary Rotation
Authors: Cao Xin , Paty Carol 
Published: December 2020

AbstractTo investigate the diurnal variations of the magnetopause boundary under different Interplanetary Magnetic Field (IMF) orientations during the solstice season, we implemented a multifluid magnetohydrodynamic model of Uranus' magnetosphere in combination with Voyager 2 observations, which provided a good ability to simulate and predict the variability of the magnetospheric boundaries. In this study, we quantitatively studied Uranus' magnetopause in terms of the subsolar stand‐off distance and the flaring parameter and tracked the variation in cusp indentation, which are good indicators to describe the general topology of the boundary. During this season, the stand‐off distance fluctuated within a small range. In contrast, the flaring parameter and cusp indentation were strongly impacted by Uranus' rotation. Meanwhile, the IMF orientation also modulated the variation of the flaring parameter and cusp indentation. These results show that the asymmetry of the magnetopause is highly dependent on the rotation of Uranus and its IMF orientations.
Ionospheric Response Over Brazil to the August 2018 Geomagnetic Storm as Probed by CSES‐01 and Swarm Satellites and by Local Ground‐Based Observations
Authors: Spogli L. , Sabbagh D. , Regi M. , Cesaroni C. , Perrone L. , Alfonsi L. , Di Mauro D. , Lepidi S. , Campuzano S. A. , Marchetti D. , De Santis A. , Malagnini A. , Scotto C. , Cianchini G. , Shen Xu Hui , Piscini A. , Ippolito A. 
Published: December 2020

AbstractThe geomagnetic storm that occurred on 25 August 25 2018, that is, during the minimum of solar cycle 24, is currently the strongest ever probed by the first China Seismo‐Electromagnetic Satellite (CSES‐01). By integrating the in situ measurements provided by CSES‐01 (orbiting at altitude of 507 km) and by Swarm A satellite (orbiting at ca., 460 km) with ground‐based observations (ionosondes, magnetometers, and Global Navigation Satellite System receivers), we investigate the ionospheric response at lower‐ and mid‐latitudes over Brazil. Specifically, we investigate the electrodynamic disturbances driven by solar wind changes, by focusing on the disturbances driving modifications of the equatorial electrojet (EEJ). Our proposed multisensor technique analysis mainly highlights the variations in the topside and bottomside ionosphere, and the interplay between prompt penetrating electric fields and disturbance dynamo electric fields resulting in EEJ variations. Thanks to this approach and leveraging on the newly available CSES‐01 data, we complement and extend what recently investigated in the Western South American sector, by highlighting the significant longitudinal differences, which mainly come from the occurrence of a daytime counter‐EEJ during both 25 and 26 August at Braziliian longitudes and during part of 26 August only in the Peruvian sector. In addition, the increased thermospheric circulation driven by the storm has an impact on the EEJ during the recovery phase of the storm. The observations at the CSES‐01/Swarm altitudes integrated with the ground‐based observation recorded signatures of equatorial ionospheric anomaly crests formation and modification during daytime coupled with the positive ionospheric storm effects at midlatitude.
Nonlinear Least Squares Fitting Technique for the Determination of Field Line Resonance Frequency in Ground Magnetometer Data: Application to Remote Sensing of Plasmaspheric Mass Density
Authors: Boudouridis A. , Yizengaw E. , Moldwin M. B. , Zesta E. 
Published: December 2020

AbstractThe accurate determination of the field line resonance (FLR) frequency of a resonating geomagnetic field line is necessary to remotely monitor the plasmaspheric mass density during geomagnetic storms and quiet times alike. Under certain assumptions the plasmaspheric mass density at the equator is inversely proportional to the square of the FLR frequency. The most common techniques to determine the FLR frequency from ground magnetometer measurements are the amplitude ratio (AR) and phase difference (PD) techniques, both based on geomagnetic field observations at two latitudinally separated ground stations along the same magnetic meridian. Previously developed automated techniques have used statistical methods to pinpoint the FLR frequency using the AR and PD calculations. We now introduce a physics‐based automated technique, using nonlinear least squares fitting of the ground magnetometer data to the analytical resonant wave equations, that reproduces the wave characteristics on the ground, and from those determine the FLR frequency. One of the advantages of the new technique is the estimation of physics‐based errors of the FLR frequency, and as a result of the equatorial plasmaspheric mass density. We present analytical results of the new technique, and test it using data from the Inner‐Magnetospheric Array for Geospace Science ground magnetometer chain along the coast of Chile and the east coast of the United States. We compare the results with the results of previously published statistical automated techniques.
On the Problem of Modeling the Boat Wake Climate: The Florida Intracoastal Waterway
Authors: Forlini Carola , Qayyum Rizwan , Malej Matt , Lam Michael‐Angelo Y.‐H. , Shi Fengyan , Angelini Christine , Sheremet Alex 
Published: December 2020

AbstractQuantifying and forecasting the impact of boat traffic on the health of coastal ecosystems must account for the multiscale nature of the process: from minutes (individual wakes), to days (tidal phase), weeks, and longer (tide modulation, seasonal traffic). Direct numerical simulations covering all these scales are difficult, not in the least because specifying the vessel type and navigation characteristics for every wake is practically impossible. To overcome this problem, we propose a statistical‐mechanics description of the wake field that focuses on classes of wakes, defined by a set of characteristic parameters, and their joint probability density in the characteristic‐parameter space. Here, we demonstrate the first steps of the approach using existing numerical tools and parametrizations. Because vessel type and navigation characteristics are not available, an investigation of wake parameter space is not possible at this time. Instead, we use the leading‐order Froude‐number parametrization defined by a linear model to classify the wake population observed during the field experiment. Numerical tests applying the FUNWAVE‐TVD model across all wake‐classes identified show excellent skills for weakly dispersive wakes. The model is challenged by the short waves generated by small, slow boats. However, simulations suggest that the problem is confined to the deeper water domain and linear evolution. Nonlinear wake shoaling, essential for modeling wake‐induced sediment transport and wake impact on the environment, is described well.
Cenozoic Evolution of the Sulu Sea Arc‐Basin System: An Overview
Authors: Lai Chun‐Kit , Xia Xiao‐Ping , Hall Robert , Meffre Sebastien , Tsikouras Basilios , Rosana Balangue‐Tarriela Maria Ines , Idrus Arifudin , Ifandi Elena , Norazme Nur 'aqidah 
Published: December 2020

AbstractThe Cenozoic Sulu Sea arc‐basin system is situated in the tectonic junction between the South China Sea (SCS), northern Borneo, Palawan Continental Terrane, Philippine Mobile Belt, and Celebes Sea. We compare new/published geochronological and geochemical data from across the circum‐Sulu Sea region, and summarize seven major magmatic phases from the Middle Eocene to Pleistocene. The Middle Eocene (42.65 Ma) Sabah ophiolite and Eocene‐Oligocene (34‐33 Ma) Central Palawan ophiolite have MORB‐IAT‐transitional features, representing an intraoceanic subduction setting in the Paleogene northern Borneo and central‐southern Palawan. After the SCS opening (∼32 Ma) and ridge jump (∼25 Ma), late‐stage Proto‐SCS subduction (24‐21 Ma) may have formed the Panay arc andesite and the BABB magmatism in SW Zamboanga peninsula. Starting of final convergence between the Palawan Continental Terrane and northern Borneo‐SW Philippines (∼21 Ma) likely caused regional uplift/thrusting, forming the Top Crocker Unconformity and triggering the NW‐dipping Celebes Sea subduction. The subduction may have formed arc magmatism (21‐18 Ma) in the Cagayan ridge and its continuation in Panay and NE Sabah, and opened the NW Sulu Sea back‐arc basin through continental crust attenuation. Subduction rollback likely occurred in 17‐14 Ma and 13‐9 Ma, shifting arc magmatism southeast to the Sulu ridge and opening the SE Sulu Sea back‐arc basin. NW‐dipping Celebes Sea subduction largely ceased after ∼9 Ma, followed by extension‐related uplift/exhumation and 4‐0.2 Ma intraplate volcanism in northern Borneo. SE‐dipping Sulu Sea subduction likely occurred along the Negros‐Sulu trenches, and produced arc volcanism from ∼4 Ma.
Optimised Levenshtein centroid cross‐layer defence for multi‐hop cognitive radio networks
Authors: Ganesh Davanam , Kumar Thummala Pavan , Kumar Malchi Sunil 
Published: December 2020

AbstractCognitive radio networks (CRN) make use of dynamic spectrum access to communicate opportunistically. Unlicensed users severely affect the spectrum sensing outcomes in CRN. Primary user emulation attack (PUEA) and spectrum sensing data falsification (SSDF) have become a paramount concern in CRNs. It is especially challenging when both masquerading (in the physical layer) and falsification (in the data link layer) occur by providing false spectrum reports. Existing methods to detect such attacks cannot be utilised in scenarios with multi‐hop CRN. In this study, to mitigate attack against PUEA and SSDF, a method called optimised sensing and Levenshtein nearest centroid classification (OS‐LNCC) for multi‐hop CRN is presented. First, a network model for multi‐hop CRN is designed. Next, a probable density optimal logical sensing model is designed to alleviate the problems related to falsification of spectrum reports. Here, the falsification of spectrum reports is overcome by exploiting dual factors, that is, probability for false alarm and probability for detection according to the departure rate of primary user (PU). With these dual factors, optimal logical sensing is made, therefore improving the throughput with minimum delay. Finally, each cognitive radio (CR) user evaluates its current sensing information to existing sensing classes through the Levenshtein distance function. Based on quantitative variables, the prediction function of each sensing class is measured using nearest centroid (NC) classifier and the sensing report is classified into either presence or absence of PU. These predictive classes are then integrated at the fusion centre so that robust mitigation against PUEA and SSDF is made. Computer simulation outputs show that OS‐LNCC method performs better than the conventional methods using metrics such as sensing delay by 47%, percentage of error in prediction by 46% and throughput by 45%.
Robust fault tolerant control allocation for a modern over‐actuated commercial aircraft
Authors: Vile Liam , Alwi Halim , Edwards Christopher 
Published: December 2020

AbstractThis paper presents a novel form of control allocation, designed within a sliding mode framework, for the fault tolerant control of over‐actuated systems. The control allocation is designed in such a way as to allow a subset of the actuators to remain inactive under nominal fault‐free conditions. In the event that the active set of actuators becomes unable to provide the desired performance, an adaption process takes place which allows the inactive actuators to compensate. A computationally light gradient descent algorithm is proposed to govern the adaption which guarantees that, if possible, actuator saturation is avoided and system performance is maintained, even in the event of severe actuator faults/failures. Rigorous conditions are derived, in terms of the faults/failures, uncertainties in fault reconstruction information and the adaptive process, which ensure sliding occurs in a finite time and that the resulting motion is stable. To demonstrate the effectiveness of the control scheme, a high‐fidelity blended wing body aircraft model is also proposed in this paper; this particular configuration of aircraft is nominally unstable, with poor control authority and a large amount of redundancy, making it a suitable candidate for testing reconfigurable fault tolerant control laws in the presence of input constraints.
Interconnection structure preservation design for a type of port‐controlled hamiltonian systems—A parametric approach
Authors: Zhao Tianyi , Duan Guangren 
Published: December 2020

AbstractIt is a very important issue to minimise the change of the interconnect structure matrix when stabilising a port‐controlled Hamiltonian (PCH) system. Toward this problem, a parametric design method is proposed in this paper for a type of PCH systems. First, concepts of H‐damping‐assignable and H‐damping‐assigning controller are introduced, and the stability of the closed‐loop system resulting from this type of controller is discussed. Secondly, a necessary and sufficient condition for the system to be H‐damping‐assignable is given, and, when this condition is met, a parametric general expression of all the H‐damping‐assigning controllers is obtained. Thirdly, the free parameters are optimised to minimize the change of the interconnect structure matrix and also the norm of the control gain matrix. The parameter optimisation is formulated as a standard quadratic programming problem, to which analytical solutions are obtained. Finally, comparative simulations are carried out for a numerical example to verify the effect and the superiority of the proposed method.
Observer for non‐linear systems with sampled measurements: Application to the friction factor estimation of a pipeline
Authors: Hernández‐González O. , Ramírez‐Rasgado F. , Astorga‐Zaragoza C. M. , Guerrero‐Sánchez M. E. , Valencia‐Palomo G. , Rodriguez‐Mata A. E. 
Published: December 2020

AbstractThis paper presents a new approach of the continuous‐discrete observer design for a class of uncertain state‐affine non‐linear systems. A high‐gain observer redesign is developed and analysed under insightful conditions. The proposed observer estimates the state vector by using system output measurements with long sampling times. This result is achieved by considering a persistent excitation condition that can be validated online. The performance of the proposed algorithm is evaluated under time‐varying sampled measurements to estimate the friction factor of a pipeline where the case of noisy sampled output measurements is also considered.
Applicability study of single‐phase reclosing in tie line of photovoltaic power plant
Authors: Xu Kehan , Zhang Zhe , Lai Qinghua , Yin Xianggen , Wei Liu 
Published: December 2020

AbstractOverhead transmission line faults are mostly single‐phase grounding faults, and to ensure the power supply reliability of photovoltaic power plants in the cases of tie line transient faults, a feasible solution is to employ the single‐phase reclosing. However, for the single‐phase reclosing of the tie line, photovoltaic power source may face the over‐voltage problem during the non‐full phase operation, which will seriously affect the success rate of the single‐phase reclosing. This paper, according to different non‐full phase operation control strategies of photovoltaic power source, establishes the corresponding sequence network analysis models, and proposes the theoretical calculation method of non‐full phase operation voltage, which takes account of different neutral point grounding modes of step‐up transformer and different load levels. Meanwhile, the closing impulse problem of the single‐phase reclosing is discussed. The correctness of the theoretical method is verified by digital simulation results. On this basis, the applicable scope and application suggestions of the single‐phase reclosing are given. The research conclusions can provide important guidance and reference for the application of single‐phase reclosing technology in tie line of renewable energy power plant.
Decentralised inverter control for improved reactive power sharing and voltage profile in a microgrid
Authors: Dheer Dharmendra Kumar , Gupta Yusuf , Doolla Suryanarayana 
Published: December 2020

AbstractThis paper enhances a self‐adjusting droop control strategy further to achieve an improved voltage profile in a microgrid along with proportional reactive power sharing amongst its sources. The proposed enhancement consists of an additional term in the “self‐adjusting” nominal voltage. The proposed strategy is entirely decentralised and does not require information about the feeder impedance or the network topology. The proposed technique is robust and found to improve the voltage profile and the reactive power sharing for radial, meshed as well as reconfigured microgrid networks. Simulation studies have been performed on two test microgrids to assess and compare the performance of the proposed strategy. Experimental validation to confirm further the viability of the proposed strategy for several topological structures of the microgrid is done on a laboratory‐scale microgrid.
Epipolar geometric association distance: A new cost function for passive sensor data association
Authors: Ma Feng , Lu Huanzhang , Zhang Luping , Shen Xinglin 
Published: December 2020

AbstractThe traditional way of passive sensor data association relies on the estimation of candidate target position, and hence suffers from severe performance degradation due to the estimation error and the so‐called ghosts. The proposed new cost function is based on epipolar geometry theory that uses fundamental matrix to measure the correlation between sensor measurements directly without estimation of candidate target position. This approach has two superiorities: (1) it declines the accuracy loss caused by a large number of trigonometric operations, and (2) it greatly immunes to the impact of ghosts. A comparison with three traditional cost functions via numerical experiments demonstrates that the proposed cost function significantly improves the accuracy of data association, especially when the number of targets is more and the sensor distribution is closer.
Multi‐sensor particle filtering with multi‐step randomly delayed measurements
Authors: Chen Yunqi , Yan Zhibin 
Published: December 2020

AbstractThis paper develops particle filtering for multi‐sensor systems with randomly delayed measurements, where the general case that random delay can be multi‐step rather than one‐step or two‐step is considered. Moreover, different sensors can have different delay steps and delay probabilities. Random delays are assumed to be mutually independent for different sensors and modelled by a separate sequence of random variables obeying discrete distributions. Since random delay leads to the actual measurements being dependent rather than independent given states, and this dependence becomes more complicated with the increase of random delay step, a new formula of the local likelihood density is proposed and then a new weighting scheme is adopted in particle filtering to deal with these difficulties. The proposed method is applied to two examples to testify its effectiveness and superiority.
Impact of COVID-19 Pandemic on Interventional Radiology Practice—A Multicenter Observational Study
Authors: Cherian Mathew , Mehta Pankaj , Barath Sitaram , Yadav Manish , Pandi Muthurajan , Joshi Saurabh , Kareparambil Ranasingh Rahul , Monga Akhil , Muthugounder Athiyappan Karthikeyan , Handihal Reddy Nikhil 
Published: December 2020

Abstract
Background The COVID-19 pandemic has brought unprecedented challenges to health care services including interventional radiology (IR). Treating COVID-19 infected patients became a priority; furthermore, government policies of differing elective procedures and the public’s fear of contacting COVID-19 have impacted IR workload worldwide. The aim of this study was to evaluate the impact of the COVID-19 pandemic on the workflow in six vascular IR centers located across India.
Methods The data were collected retrospectively from April 1 to June 30, 2020. All the six centers were staffed by the alumni of a single parent center located in India. Data was also collected from the same time period in 2019 for comparison.
Results A total of 893 patients were treated from April 1 to June 30, 2019, and 419 were treated during the same period in 2020 during the pandemic, a 53% case volume reduction (95% CI:28. 56–129.44; p < 0.001). The month of April had the largest case volume reduction (66%, 95% CI: 13.57–50.43; p < 0.001). Elective procedures showed an 85% reduction (95% CI: 9.62–91.71; p < 0.001). Venous interventions showed the highest reduction of 76% (95% CI: 0.75–67.75; p < 0.001). Neurological emergencies, dialysis-related interventions, and nonvascular procedures did not show a significant change. No patient tested positive for COVID-19 prior to the procedure; however, one patient who was treated emergently was found to be positive later.
Conclusion COVID-19 pandemic has severely impacted IR practice across India. Workload reduction was more profound at the beginning of the COVID-19 pandemic with a gradual improvement over time.
Nerve Grafting in Head and Neck Reconstruction
Authors: Morgan Scott D. , Zuniga John R. 
Published: December 2020

AbstractIn head and neck reconstructive surgery, especially of the mandible, the long-span processed nerve allograft (PNA) is a technological advancement that provides improved quality of life for patients who require ablative surgery by allowing for functional sensory recovery (FSR) in the majority of patients treated with immediate reconstruction. Recently published clinical prospective and retrospective multisite controlled cohort studies of immediate nerve reconstruction at the time of ablative surgery, including pediatric patient populations, were reviewed for valid and predictable outcomes of FSR following the reconstruction of the inferior alveolar nerve using > 5-cm PNA allografts. Both adult and pediatric patients demonstrate high percentages of FSR within 1 year. Pediatric patients demonstrate robust recovery with 100% reaching FSR within 1 year, whereas 89% of adults achieved FSR during the same time span; the pediatric patient population reached FSR earlier when compared with adults. Control, nonallograft nerve repair patients never achieved FSR, reaching only S2 levels in both adults and pediatric groups. There were no adverse events; in fact, no patients demonstrated the occurrence of neuropathic pain when the nerve repair was performed immediately in contrast to delayed repair states. Long-span (> 5-cm) nerve allografts provide FSR in pediatric patients and the majority of adult patients and should be used in patients who require ablation of the mandible for head and neck reconstruction.