bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of Cognition in Common Measures of Peripheral Synaptopathy and Hidden Hearing Loss
Authors: Kamerer Aryn M. , AuBuchon Angela , Fultz Sara E. , Kopun Judy G. , Neely Stephen T. , Rasetshwane Daniel M.
Published: October 2019

Purpose

The aim of this study was to quantify the portion of variance in several measures suggested to be indicative of peripheral noise-induced cochlear synaptopathy and hidden hearing disorder that can be attributed to individual cognitive capacity.

Method

Regression and relative importance analysis was used to model several behavioral and physiological measures of hearing in 32 adults ranging in age from 20 to 74 years. Predictors for the model were hearing sensitivity and performance on a number of cognitive tasks.

Results

There was a significant influence of cognitive capacity on several measures of cochlear synaptopathy and hidden hearing disorder. These measures include frequency modulation detection threshold, time-compressed word recognition in quiet and reverberation, and the strength of the frequency-following response of the speech-evoked auditory brainstem response.

Conclusions

Measures of hearing that involve temporal processing are significantly influenced by cognitive abilities, specifically, short-term and working memory capacity, executive function, and attention. Research using measures of temporal processing to diagnose peripheral disorders, such as noise-induced synaptopathy, need to consider cognitive influence even in a young, healthy population.
Multi‐class import vector machine for transmit antenna selection in MIMO systems
Authors: Yang Xiaofeng , Zhao Feng
Published: October 2019

Antenna selection is a promising solution to reduce the high cost of multiple RF chains in multiple‐input multiple‐output (MIMO) systems while maintaining the benefits of spatial diversity and multiplexing gain. By modelling the problem of transmit antenna selection as a multi‐class classification and/or decision‐making task, this Letter proposed a multi‐class import vector machine (IVM) based approach to maximise the average received signal‐to‐noise ratio (SNR). Simulation results prove that IVM outperforms the conventional optimisation driven algorithm and the state‐of‐the‐art learning‐based scheme of support vector machine in terms of average received SNR performance with feasible complexity and sparsity.
Method for identifying ageing in epoxy‐mica composite insulation used in rotational machines through modelling of dielectric relaxation
Authors: Mondal Nikhil , Haque Nasirul , Dalai Sovan , Chakravorti Sivaji , Chatterjee Biswendu
Published: October 2019

Dielectric response analysis, performed in time domain and frequency domain is one of the interesting methods used for condition assessment of high voltage equipment. In this article, the degradation of epoxy‐mica composite insulation which is widely used in rotating machines has been investigated through frequency domain spectroscopy measurements. Artificial ageing of the carefully prepared stator bar insulation sample was performed through simultaneous application of high temperature and electric field in a designated environmental chamber for specific durations. To study the effect of temperature, the measurements were performed at temperatures ranging from 20 to 60°C at different ageing status. Following experimental work, the measurement results were modelled using Havriliak–Negami model and ageing sensitive parameters were extracted. To study the effect of temperature, the measurements were performed at temperatures ranging from 20 to 60°C. The modelled results matched well with the experimental measurements and certain model parameters sensitive to the ageing condition were identified. The numerical relationships between the insulation status of the stator bar and the aforementioned parameters were identified. It was observed that the nature of the numerical relationship remains identical in the investigated temperature range, although the coefficients vary to some extent.
Electronic transformer performance evaluation and its impact on PMU
Authors: Li Jue , Liu Hao , Martin Kenneth E. , Li Jinsong , Bi Tianshu , Yang Qixun
Published: October 2019

The electronic transformer of smart substations, which transfers primary signals, is important for measurements and controls. In this study, the transformation characteristics of a Rogowski electronic current transformer (ECT) are analysed theoretically. Then, experimental platforms are established to verify the analysis and study the impact of the transformation characteristics of the ECT and an electronic voltage transformer (EVT) on a phasor measurement unit (PMU) using standard test signals. The analysis and the testing results show that this ECT can transfer the phasor well under both steady and dynamic conditions. However, the harmonics introduced by the ECT may lead to the measurement errors of frequency and the rate of the change of the frequency (ROCOF) from the PMU. Therefore, a phasor algorithm with powerful DC offset and harmonics immunity is suggested for PMUs connected to the output of this type of ECT. For the EVT, the ROCOF measurements are easily affected as well. The EVT was also shown to be more sensitive to temperature than the potential transformer (PT).
Bi‐level optimisation dispatch method for photovoltaic hosting capacity enhancement of distribution buses
Authors: Wang Hongkun , Wang Shouxiang , Zhao Qianyu , Wang Jianfeng
Published: October 2019

Distributed photovoltaic (PV) systems are being gradually integrated into distribution systems with the advantage of economy, environmental protection, and flexibility. Hosting capacity (HC) of a distribution system limited the integration of the PVs. To identify the economic efficiency of HC, two boundaries of HC for distribution buses are proposed considering the technology and economy. Then, new evaluation metrics that can identify the HC region for the PV buses are presented. A bi‐level optimisation dispatch method based on iterative particle swarm optimisation for PVHC enhancement is proposed considering the benefits of both distribution network operators and PV owners. At the upper level, a linear power flow‐based model is used to determine the economic PVHC and technological PVHC. At the lower level, the objective function of the maximisation of benefits for PV owners is presented. The punishment coefficient of the PVHC region is incorporated into the optimisation dispatch model. Finally, the demonstration is performed on modified PG&E 69‐bus and IEEE 123‐bus distribution systems. The simulation results show that the proposed bi‐level optimisation dispatch method can effectively increase the PVHC margin of distribution buses, and the presented evaluation metrics are of great practical significance in a deregulated environment.
Prevention and mitigation of high‐voltage direct current commutation failures: a review and future directions
Authors: Zhu Yanan , Zhang Shuqing , Liu Dong , Zhu Lin , Zou Sheng , Yu Siqi , Sun Yubo
Published: October 2019

With the increasing applications of high‐voltage direct current inverters in heavy‐load grids, commutation failures (CFs) pose a severe threat to the safe and stable operation of power systems. This study first sorts methods of CF inhibition into different categories and then investigates their effectiveness, adaptability and limitations. Considering the economic benefits and applicability, CF inhibition calls for integrated methods involving supplementary power devices, control strategies and prediction techniques. Finally, this study makes clear potential future research directions, suggesting first control potential is exploited by machine learning‐based control, and then auxiliary devices to be added if necessary.
Blur parameter locus curve and its applications
Authors: Kumar Himanshu , Gupta Sumana , Subramanian Venkatesh K.
Published: October 2019

Conventionally, the point spread function (PSF) is understood as a characteristic function of any optical system. It captures the information about the amount of blur present along all the directions for a point in the scene. However, the dependence of blur on the PSF is in the form of convolution for any object other than a point source present in the scene and hence their relationship is less explicit. The authors propose a blur parameter locus curve (BPLC) as a system representation which has a one to one relationship with blur. BPLC simply is a chart of blur amounts in all directions of a given PSF with respect to the selected measurement function. They further characterise the PSF by decomposing the variation of BPLC across all directions based on the study performed for different possible forms of the blur kernels. Such decomposition provides powerful tools for various analysis. As PSF can be anisotropic, the computation of BPLC becomes an essential intermediate step to obtain the scale map as at the same scale, blur is different in different directions. Furthermore, they demonstrate the use of BPLC to obtain other system characteristics function such as PSF.
Ensemble of deep convolutional neural networks based multi‐modality images for Alzheimer's disease diagnosis
Authors: Fang Xusheng , Liu Zhenbing , Xu Mingchang
Published: October 2019

Alzheimer's disease (AD) is one of the most common progressive neurodegenerative diseases. Structural magnetic resonance imaging (MRI) would provide abundant information on the anatomical structure of human organs. Fluorodeoxy‐glucose positron emission tomography (PET) obtains the metabolic activity of the brain. Previous studies have demonstrated that multi‐modality images could contribute to improve diagnosis of AD. However, these methods need to extract the handcrafted features that demand domain specific knowledge and image processing stage is time consuming. In order to tackle these problems, in this study, the authors propose a novel framework that ensembles three state‐of‐the‐art deep convolutional neural networks (DCNNs) with multi‐modality images for AD classification. In detail, they extract some slices from each subject of each modality, and every DCNN generates a probabilistic score for the input slices. Furthermore, a ‘dropout’ mechanism is introduced to discard low discrimination slices of the category probabilities. Then average reserved slices of each subject are acquired as a new feature. Finally, they train the Adaboost ensemble classifier based on single decision tree classifier with the MRI and PET probabilistic scores of each DCNN. Evaluations on Alzheimer's Disease Neuroimaging Initiative database show that the proposed algorithm has better performance compared to existing method, the algorithm proposed in this study significantly improved the classification accuracy.
High‐performance control method for the MSTMP motor
Authors: Zhang Haifeng , Liu Gang
Published: October 2019

Permanent magnet synchronous motor (PMSM) is the ideal drive for the magnetically suspended turbo‐molecular pump (MSTMP) for its high power density, reliable operation and high energy efficiency. Rotor position information is necessary to drive the PMSM. However, because of the installation space limitation and reliability requirement, position sensorless control technology without mechanical position sensors is more attractive. In this study, a sliding mode observer is adopted to estimate the back electromotive force (EMF) that contains the position information. Since the high‐order harmonics in the back EMF would lead to harmonic position errors, a fixed frequency extraction filter is proposed to filter out the harmonics. A high precision speed control is of importance to ensure the performance of the MSTMP and also contributes to achieving a better position estimation accuracy, especially under strong disturbances. Therefore, a composite speed controller combining a sliding mode speed controller and a sliding mode disturbance observer is proposed to improve the speed control performance of the MSTMP. The effectiveness of the proposed high‐performance control method for the MSTMP motor is evaluated with experiments.
Multi‐sensors in‐line inspection robot for pipe flaws detection
Authors: Le Dinh Van‐Khoa , Chen Zhiyuan , Rajkumar Rajprasad
Published: October 2019

In‐line inspection (ILI) robot has been considered as an inevitable requirement to perform non‐destructive testing methods efficiently and economically. The detection of flaws that could lead to leakages in buried concrete pipes has been an area of great concern to the oil and gas industry and water resource‐based industry. The major problem is the difficulty in modelling the detection of cracks as a result of its irregularity and randomness that cannot be easily detected. This work covers the study of defect detection of non‐destructive testing methods using fusion inspect sensors, light detection and ranging, and optic sensors. Studies on ILI robots are also reviewed to construct an efficient gauge. Nevertheless, the study on current support vector machine (SVM) technique is centred as the main classification engine for the combined sensory data. The prototype robot has been designed and successfully operated in a lab‐scale environment. Intuitively, the obtained data described the status of inspected pipe clearly. Sensors from the proposed list also well integrated as attaching to the robot. The experiments with SVM techniques to evaluate the feasibility of defects detection also achieved remarkable results.
Hypnosis regulation in propofol anaesthesia employing super‐twisting sliding mode control to compensate variability dynamics
Authors: Ilyas Muhammad , Iqbal Jamshed , Ahmad Sayyar , Uppal Ali Arshad , Imtiaz Waqas Ahmad , Riaz Raja Ali
Published: October 2019

Regulation of hypnosis level on bi‐spectral index monitor (BIS) during a surgical procedure in propofol anaesthesia administration is a challenging task for an anaesthesiologist in multi‐tasking environment of the operation theater. Automation in anaesthesia has the potential to solve issues arising from manual administration. Automation in anaesthesia is based on developing the three‐compartmental model including pharmacokinetics and pharmacodynamic of the silico patients. This study focuses on regulation of the hypnosis level in the presence of surgical stimulus including skin incision, surgical diathermy and laryngoscopy as well as inter‐patient variability by designing super‐twisting sliding mode control (STSMC). The depth of the hypnosis level is maintained to 50 on the BIS level in the maintenance phase after improving the induction phase to 60 s using the conventional sliding mode control and 30 s with STSMC. The proposed scheme also compensates the inter‐patient variability dynamics including height, age and weight of the different silico patients. Moreover, the surgical stimuli direct the hypnosis level towards the state of consciousness and stimulate the controller to provide continuous drug infusion during the interval 80–90 s. Simulation results witness that the oscillatory behaviour is observed in drug infusion to ensure the moderate level of hypnosis (40–60) for general surgery.
Maintenance robot motion control based on Kinect gesture recognition
Authors: Ge Lun , Wang Hongjun , Xing Jishou
Published: October 2019

Maintenance robot is used widely in industries due to its convenience. The maintenance robot system is introduced. The hardware frame is designed in detail. Based on gesture recognition, the effect of controlling the robot movement is achieved. Gesture recognition information is achieved through the acquisition of human skeleton information by a Kinect sensor. The construction of the gesture library is done. The maintenance robot control system is set up to control the omnidirectional mobile robot driven by the Mecanum wheel. Finally, the maintenance robot is developed and the design functions are carried out.
Compressed spatial–spectral feature representation for hyperspectral ground classification
Authors: Shichao Zhou , Baojun Zhao , Linbo Tang , Wenzheng Wang
Published: October 2019

The difficulty of classification tasks in hyperspectral imagery (HSI) strongly depends on the representation of spectral or spatial information. Vast amounts of approaches have been proposed to deal with spectral and spatial feature extraction, respectively. However, most of the methods neglect the inherent relationships between them. Inspired by the extreme learning machine (ELM) theory, the authors propose a new fusion‐ELM framework for multiple sources representation learning and fusion. The resultant features are utilised to deal with HSI classification. With the multiple network channels and aggregation layers, the presented scheme could achieve spatial and spectral feature representations of inputs, respectively, and obtain optimal joint feature. Experimental results show that their fusion‐model leads to decent improvements in classification accuracy over spectral‐only, spatial–spectral‐joint model and deep learning framework on two hyperspectral benchmarks.
Approach of SAR images simulations for target interpretations
Authors: Zhang Yueting , Ding Chibiao , Lei Bin , Li Fangfang , Qiu Xiaolan
Published: October 2019

In this work, a novel approach for the simulation of synthetic aperture radar (SAR) images is proposed. Also, this approach aims to interpret the mechanisms of the dominated scattering centres in the SAR image. An attributed model based on typical structures is used to characterise the 3D geometry of the targets. The physical optics and the geometry optics are used to calculate the main scattering mechanisms of the specified typical structures. Also, based on scattering properties and the imaging process, the simulation approach is set up. The experiments based on the Terra‐SAR data of an airplane are implemented to test the validity of the simulation. The work presented would be useful for SAR automatic target recognition.
Index for task scheduling in phased array radar
Authors: Duan Yi , Tan Xian‐Si , Qu Zhi‐Guo , Wang Hong
Published: October 2019

In the task scheduling problem of phased array radar, the objective function is usually based on the time shifting rate (TSR). However, the TSR cannot achieve expected scheduling performance in non‐linear filtering systems. To further improve the scheduling performance, a novel index named shifting improve rate (SIR) is proposed by analysing the influence of time shifting and its formula in Kalman filtering and expand Kalman filtering is derived. Based on SIR, a new objective function for scheduling of phased array radar tasks was designed and used the genetic algorithm to solve it. Simulated experiments are done to validate the proposed index and the new objective function. The results demonstrate that the SIR achieves better scheduling performance and tracking accuracy than TSR in non‐linear filtering systems while keeping similar performance in linear filtering systems.
Sequential optimisation of orthogonal waveforms for MIMO radar
Authors: Huang Zhongrui , Tang Bo , Zhang Shuo
Published: October 2019

The existing methods to design orthogonal waveforms for multiple‐input multiple‐output radar mainly focus on the optimisation of autocorrelation and cross‐correlation properties. Their performance will degrade severely in the presence of Doppler shifts. To overcome this limitation, the authors take an unknown Doppler shifts range into consideration and formulate a new waveform optimisation problem. Since the optimisation problem is highly non‐linear, the authors propose an algorithm, called sequential cone programming, to tackle it. The key idea is to use the first‐order Taylor expansion to approximate the constraints at each iteration. The authors show that the approximation can be solved via second‐order cone programming. In addition, the autocorrelation peak sidelobe level and cross‐correlation peak level could be further reduced by setting an appropriate threshold function. Simulation results demonstrate the efficiency of the proposed method compared with state‐of‐art methods.
Opto‐electrical properties of HAT‐CN based organic light emitting diode
Authors: Jain Neha , Sinha Om Prakash , Pandey Sujata , Singh Rajiv Kumar
Published: October 2019

1,4,5,8,9,11‐hexaazatriphenylene‐hexacarbonitrile (HAT‐CN)‐based organic light emitting diode (OLED) have been simulated, fabricated, and characterised. HAT‐CN has been inserted as an organic interlayer at the indium tin oxide/organic interface. It has been observed that there is a significant increase in the current density of the device. Also, the electroluminescence (EL) intensity of the OLED device is in contrast with J–V characteristics, i.e. EL intensity and current density is maximum at 22 nm Alq3 layer thickness. There is an approximate increase of 0.13 A/cm2 in current density with respect to the applied voltage when the Alq3 thickness is varied from 20 to 22 nm. The maximum current density obtained is 0.4 A/cm2. EL intensity is approximately increased by 30% at the same Alq3 thickness. A comparison of fabricated and simulated optoelectronic devices has also been reported in this work. They have found proximity between the fabricated and simulated devices.
Surprises in the simultaneous X-ray and optical monitoring of π Aquarii
Authors: Nazé Yaël , Rauw Gregor , Smith Myron
Published: October 2019

To help constrain the origin of the peculiar X-ray emission of γ Cas stars, we conducted a simultaneous optical and X-ray monitoring of π Aqr in 2018. At that time, the star appeared optically bright and active, with a very strong Hα emission. Our monitoring covers three 84 d orbital cycles, allowing us to probe phase-locked variations as well as longer-term changes. In the new optical data, the radial velocity variations seem to span a smaller range than previously reported, which might indicate possible biases. The X-ray emission is variable, but without any obvious correlation with orbital phase or Hα line strength. Furthermore, the average X-ray flux and the relative range of flux variations are similar to those recorded in previous data, although the latter data were taken when the star was less bright and its disk had nearly entirely disappeared. Only the local absorption component in the X-ray spectrum appears to have strengthened in the new data. This absence of large changes in X-ray properties despite dramatic disk changes appears at odds with previous observations of other γ Cas stars. It also constrains scenarios proposed to explain the γ Cas phenomenon.
An outer shade of Pal: Abundance analysis of the outer halo globular cluster Palomar 13
Authors: Koch Andreas , Côté Patrick
Published: October 2019

At a Galactocentric distance of 27 kpc, Palomar 13 is an old globular cluster (GC) belonging to the outer halo. We present a chemical abundance analysis of this remote system from high-resolution spectra obtained with the Keck/HIRES spectrograph. Owing to the low signal-to-noise ratio of the data, our analysis is based on a coaddition of the spectra of 18 member stars. We are able to determine integrated abundance ratios for 16 species of 14 elements, ofα-elements (Mg, Si, Ca, and Ti), Fe-peak (Sc, Mn, Cr, Ni, Cu, and Zn), and neutron-capture elements (Y and Ba). While the mean Na abundance is found to be slightly enhanced and halo-like, our method does not allow us to probe an abundance spread that would be expected in this light element if multiple populations are present in Pal 13. We find a metal-poor mean metallicity of −1.91 ± 0.05 (statistical) ±0.22 (systematic), confirming that Pal 13 is a typical metal-poor representative of the outer halo. While there are some differences between individualα-elements, such as halo-like Mg and Si versus the mildly lower Ca and Ti abundances, the mean [α/Fe] of 0.34 ± 0.06 is consistent with the marginally lowerαcomponent of the halo field and GC stars at similar metallicity. We discuss our results in the context of other objects in the outer halo and consider which of these objects were likely accreted. We also discuss the properties of their progenitors. While chemically, Pal 13 is similar to Gaia-Enceladus and some of its GCs, this is not supported by its kinematic properties within the Milky Way system. Moreover, its chemodynamical similarity with NGC 5466, a purported progeny of the Sequoia accretion event, might indicate a common origin in this progenitor. However, the ambiguities in the full abundance space of this comparison emphasize the difficulties in unequivocally labeling a single GC as an accreted object, let alone assigning it to a single progenitor.
Enhanced positive vertex-centered finite volume scheme for anisotropic convection-diffusion equations
Authors: Quenjel El Houssaine
Published: October 2019

This article is about the development and the analysis of an enhanced positive control volume finite element scheme for degenerate convection-diffusion type problems. The proposed scheme involves only vertex unknowns and features anisotropic fields. The novelty of the approach is to devise a reliable upwind approximation with respect to flux-like functions for the elliptic term. Then, it is shown that the discrete solution remains nonnegative. Under general assumptions on the data and the mesh, the convergence of the numerical scheme is established owing to a recent compactness argument. The efficiency and stability of the methodology are numerically illustrated for different anisotropic ratios and nonlinearities.
Muskuläre Belastung unterschiedlicher
Ganzkörper-Elektromyostimulations-(WB-EMS) Protokolle – eine
Crossover-Untersuchung mit Sportlern ohne WB-EMS Erfahrung
Authors: Kemmler Wolfgang
Published: October 2019

Ganzkörper-Elektromyostimulation zeichnet sich durch das
Alleinstellungsmerkmal aus, große Muskelgruppen simultan aber regional
dezidiert und ggf. supramaximal stimulieren zu können. Diese
Konstellation kann zu gesundheitlichen Risiken führen, die unter dem
Begriff der „Rhabdomyolyse“ subsumiert werden. Ziel dieses
Beitrags war es, unterschiedliche WB-EMS-Protokolle hinsichtlich ihrer
muskulären Belastung im Crossover-Verfahren zu
überprüfen, um Empfehlungen für deren Applikation
abzuleiten. Neunzehn sportliche Männer (28±5 Jahre) ohne jede
WB-EMS Erfahrung wurden randomisiert und balanciert den WB-EMS-Protokollen
Ausdauertraining (a) ohne (b) mit niedrig-moderat intensivem WB-EMS
Dauerstrom-Protokoll mit 7 Hz bzw. (c) 85 Hz sowie
Körperübungen (d) ohne bzw. (e) mit hoher, intermittierender (4s
– 4s) Impulsintensität (85 Hz) zugeordnet. Es wurde
bipolarer Strom mit einer Impulsbreite von 350 µs und direktem
Impulsanstieg/-abfall appliziert. Die Dauer des
Körperübungsprotokolls lag bei 20 min, das
Ausdauerprogramm (75% VO2max, Crosstrainer) dauerte
30 min. Als Marker der muskulären Belastung wurde Kreatinkinase
unmittelbar vor/nach, sowie 24, 48 und 72 h nach dem Test
bestimmt. Alle Ausdauervarianten zeigten einen relativ moderaten Anstieg der
CK-Konzentration um das 2,5–3 fache des Vorbelastungswertes mit Peak
nach 48 h. Zwischen den Gruppen ohne und mit bzw. hoher und niedriger
Stimulationsfrequenz konnten kein signifikanter Unterschiede erfasst werden. Die
„kraftorientierte“ WB-EMS-Variante führte zu einer
48fachen Erhöhung des Vorbelastungswertes mit Peak nach 72 h. Faktisch
kein Einfluss auf die CK-Konzentration hatten die Körperübungen
ohne WB-EMS. Wie zu erwarten zeigen sich signifikante Unterschiede hinsichtlich
der CK-Kinetik zwischen einem ausdauer- und kraftorientierten WB-EMS-Protokoll,
die primär der unterschiedlichen Impulsintensität geschuldet
sind. Diese Ergebnisse sind bei Empfehlungen zu Regenerationsdauer und
Trainingshäufigkeit unterschiedlicher WB-EMS-Protokolle zu
berücksichtigen.
Highly Chemoselective Solvent-Free Synthesis of 1,3,5-Triaryl-1,5-diketones: Crystallographic Investigation and Intramolecular Weak Bifurcated H Bonds Involving Aliphatic C–H Group
Authors: Yin Zhongyou , Xiong Changkun , Guo Jianxin , Hu Xiaoyun , Shan Zixing , Borovkov Victor
Published: October 2019

Several 1,3,5-triaryl-1,5-diketones have been chemoselectively synthesized under solvent-free conditions. It was found that intramolecular weak bifurcated H-bonds interaction of aliphatic C–H group plays a decisive role in the structural arrangement of 3-(2,6-dichlorophenyl)-1,5-diphenylpentane-1,5-dione in a solid state resulting in significant impact on the corresponding bond lengths and dihedral angles.
A Simplified Protocol for the Stereospecific Nickel-Catalyzed C–S Vinylation Using NiX2 Salts and Alkyl Phosphites
Authors: Marchese Austin D. , Mirabi Bijan , Larin Egor M. , Lautens Mark
Published: October 2019

A Ni-catalyzed C–S cross-coupling using only NiI2 (0.5–2.5 mol%) and P(OiPr)3 (2.0–10.0 mol%) is reported. Using an air-stable Ni(II) precatalyst, and a cheap and commercially available ligand, a scalable and robust method was developed to cross-couple various thiophenols and styryl bromides, including some sterically encumbered thiols, an α-bromocinnamaldehyde as well as a thiolation-cyclization.
Mass generation in Abelian U(1) gauge theories: A rich network of dualities
Authors: Bertrand Bruno , Govaerts Jan
Published: October 2019

Following a novel approach, all known basic mass generation mechanisms consistent with an exact Abelian U(1) gauge symmetry are shown to be related through an intricate network of dualities whatever the spacetime dimension. This equivalence, which applies in the absence of any supersymmetry, is however restricted by the presence of topological terms generating possible topological effects. In particular, in 3 + 1 dimensions, the duality relations between the Maxwell-Higgs model, the Stueckelberg, and the topological mass generation mechanisms are then established following a careful treatment of the gauge symmetry content. This result offers a new framework for an effective description of superconductivity or topological defects built from fields beyond the Standard Model.
Generalized Einstein relation for nonparabolic multiple energy-band degenerate semiconductors
Authors: Jyegal Jang
Published: October 2019

A generalized Einstein relation for electron gases of degenerate semiconductors with a system of typically two nonparabolic conduction band structures is derived and formulated in near-equilibrium condition based on using the semiclassical drift-diffusion equation. The result of this derivation shows that the Einstein relation for carrier gases in multiple energy bands generally depends on their mobilities unless the energy band structures are parabolic. The formulated results (a full formula and an approximate single-carrier-gas formula) are typically applied to GaAs and GaSb to calculate the values of the ratio of the diffusion coefficient to mobility for carriers in the lowest and upper conduction bands, and an in-depth investigation is made for the Einstein relation for conduction electrons in these semiconductors. It is shown, in particular, that highly degenerate GaAs exhibits the uncommon, peculiar property of the ratio of the diffusion coefficient to mobility for conduction electrons saturating in two different electron concentration, or Fermi energy, conditions, with increasing electron concentration or Fermi energy. It is also shown that for GaSb, the effect of the upper conduction band is so large that the use of any formula obtained for carriers in a single conduction band is generally unsuitable for describing the Einstein relation for conduction electrons in this semiconductor. In addition, a more generalized Einstein relation extended to a system of three nonparabolic energy band structures is also formulated and proposed in the paper, so as to be used to more accurately describe the Einstein relation for hole gases in degenerate semiconductors.
Heat exchange with interband tunneling
Authors: Li Zheng , Xue Jin , J. Ram Rajeev
Published: October 2019

The carrier transport associated with interband tunneling in semiconductors has been investigated extensively both experimentally and theoretically. However, the associated heat exchange from interband tunneling is not discussed in depth. Due to the nanoscale nature of the tunneling phenomenon, people tend to use a “resistor model” to compute the heat generated. We present our analysis of heat exchange in tunneling junctions based on an extended Kane’s model. We observe that the heat exchange is distinct when we apply forward bias, small reverse bias, and large reverse bias. In each of these bias regimes, we demonstrate that the internal temperature distribution of a tunneling junction can deviate from the simplified “resistor model” significantly.
Microwave magnon damping in YIG films at millikelvin temperatures
Authors: Kosen S. , van Loo A. F. , Bozhko D. A. , Mihalceanu L. , Karenowska A. D.
Published: October 2019

Magnon systems used in quantum devices require low damping if coherence is to be maintained. The ferrimagnetic electrical insulator yttrium iron garnet (YIG) has low magnon damping at room temperature and is a strong candidate to host microwave magnon excitations in future quantum devices. Monocrystalline YIG films are typically grown on gadolinium gallium garnet (GGG) substrates. In this work, comparative experiments made on YIG waveguides with and without GGG substrates indicate that the material plays a significant role in increasing the damping at low temperatures. Measurements reveal that damping due to temperature-peak processes is dominant above 1 K. Damping behavior that we show can be attributed to coupling to two-level fluctuators (TLFs) is observed below 1 K. Upon saturating the TLFs in the substrate-free YIG at 20 mK, linewidths of ∼1.4 MHz are achievable: lower than those measured at room temperature.
Pathways of carrier recombination in Si/SiO2 nanocrystal superlattices
Authors: Chlouba T. , Trojánek F. , Kopecký V. , López-Vidrier J. , Hernandéz S. , Hiller D. , Gutsch S. , Zacharias M. , Malý P.
Published: October 2019

We investigated picosecond carrier recombination in Si/SiO2 nanocrystal superlattices by ultrafast transient transmission, time-resolved photoluminescence, and Raman spectroscopy. The recombination is of multicarrier origin and it depends strongly on the nanoscale structure of the samples (e.g., crystallinity, percolation, and size distribution). Several recombination pathways were found, including Auger recombination, trapped-carrier Auger recombination, exciton–exciton recombination, and subsequent trapping in band tail states of amorphous silicon phase. The sample microscopic structure is determined using a single parameter, the stoichiometric parameter x, during the plasma-enhanced chemical-vapor deposition process. The percolated samples are hot candidates for all-silicon tandem photovoltaic solar cells in the future.
Electrothermal performance limit of β-Ga2O3 field-effect transistors
Authors: Mahajan Bikram K. , Chen Yen-Pu , Noh Jinhyun , Ye Peide D. , Alam Muhammad A.
Published: October 2019

A β-Ga2O3 field effect transistor (FET) outperforms a GaN FET in Baliga's figure of merit (FOM) by 400% and Huang's chip area manufacturing figure of merit by 330%, suggesting that β-Ga2O3 could be a substrate of choice for next generation power transistors. However, its low thermal conductivity leads to extreme self-heating, which deteriorates the device performance during high voltage operation. A holistic evaluation of performance from a material-device-circuit perspective is necessary before reaching any conclusion regarding the technological viability of β-Ga2O3. In this paper, we develop a multiphysics and multiscale model for a material-device-circuit analysis of β-Ga2O3 FETs. The framework allows us to explore the effectiveness of various device design strategies (e.g., thermal shunts) for mitigating the thermal chokepoints and compare the performance of improved β-Ga2O3 FETs against that of GaN and SiC FETs. We highlight the limitations of traditional FOMs to analyze the relative performance of the new generation of power transistors whose structure incorporates stacked layers of materials with different thermal conductivities, like those of β-Ga2O3 FETs. We suggest device design strategies, such as wafer thinning, incorporation of heat shunts, and improved channel mobility, so that β-Ga2O3 FETs can compete commercially with GaN and SiC technologies.
Damage mechanism of wind turbine blade under the impact of lightning induced arcs
Authors: Zhang Minhao , Li Qingmin , Li Hongbo , Yu Wanshui , Guo Zixin , Siew Wah Hoon
Published: October 2019

It is not clear for the damage mechanism of the blade structure under the effect of the lightning strike arc. In this paper, the damage characteristics of blades under the effect of an lightning arc are obtained by the impulse large current experiment. Based on the actual blade structure, a magnetohydrodynamics model is built to be suitable for multifield coupling of the heat-magnetic-airflow and we obtain the temporal and spatial variation of the temperature and pressure. The experimental results show that the blade tends to crack from the position of the trailing edge near the arc attachment point and the crack extends in the direction of the blade root and tip. The length of carbonization damage caused by the high temperature of the arc is much smaller than the crack length due to the airflow impact. When the down-conductor is placed on the main beam, carbonization damage distributes in the area between the left web and the trailing edge. When placed on the right web, it distributes between the right web and the trailing edge. In the finite element simulation, the temperature of the arc ignited point increases to the peak value and then decreases rapidly and then, it increases to the maximum and tends to stabilize. The high temperature inside the blade region diffuses from the boundary between the pressure surface and the right web to the trailing edge. The pressure of the trailing edge increases to the maximum and then oscillates to decrease. The airflow inside the blade continuously oscillates between the right web and the trailing edge. It is recommended to improve the toughness of the epoxy resin adhesive and set the down-conductor on the main beam.
Multistability and basin stability in coupled pendulum clocks
Authors: Dudkowski Dawid , Czołczyński Krzysztof , Kapitaniak Tomasz
Published: October 2019

In this paper, we investigate the phenomenon of multistability and the concept of basin stability in two coupled pendula with escapement mechanisms, suspended on horizontally oscillating beam. The dynamics of a single pendulum clock is studied and described, showing possible responses of the unit. The basin stability maps are discussed in two-parameters plane, where we vary both the system’s stiffness as well as the damping. The possible attractors for the investigated clocks are discussed, showing that different patterns of synchronization and desynchronization can occur. The oscillators may completely synchronize in one of the three possible combinations (including inphase and antiphase ones), practically synchronize with some fluctuations or stay in the irregular pattern, which includes chaotic motion. The transitions between solutions are studied, uncovering that the road from one type of dynamics into another may become very complex. Moreover, we examine the multistability property of our model using the bifurcation diagrams and the basins of attraction maps, discussing possible scenarios in which the states co-exist. The analysis of attractors’ basins uncovers complicated structure of the latter ones, exhibiting that the final behavior of investigated model may be hard to determine and trace. Our results are discussed for the cases of identical and nonidentical pendula, as well as light and heavy beam, showing that depending on considered scenario, various patterns of behaviors and transitions may be observed. The research described in this paper proves that the mechanical properties of the system’s suspension may play a crucial role in the possibility of the appearance of different types of attractors and that the basin stabilities of states strictly depend on the values of considered parameters.
A compatibility principle, analytical formulation, and the G- and Σ-equations in the theory of turbulent premixed combustion
Authors: Zimont Vladimir L.
Published: October 2019

We analyze the nature of the known difficulties that arise when trying to apply the kinematic G-equation and the surface average Σ-equation to the Reynolds-Averaged Navier–Stokes modeling of turbulent premixed combustion, based on the use of the Favre average equations of combustion and hydrodynamics. We consider this issue in the context of an analytical formulation that includes an asymptotically closed infinite system of successively derived unclosed moment combustion and hydrodynamics equations of the problem. We show that the cause of these difficulties is the incompatibility of the G-equation and Σ-equation with the other instantaneous and averaged equations of the problem. This leads us to formulate a compatibility principle, i.e., a rule for the identification of misconceptions about the use of instantaneous and averaged equations that are correct by themselves, due to their incompatibility with the equations of the corresponding analytical formulation. Special attention is devoted to a comparison of two approaches to a description of instantaneous and average premixed combustion, based on the use of the progress variable c and the scalar G. We state that these approaches are equivalent. To prove this, we derive the equations missing from these two approaches and show that the following two groups of instantaneous and Favre-averaged equations, formulated in terms of c and G, respectively, are equivalent. The main result is the proposed compatibility principle. The conclusion following from our analysis is that the concepts of the scalar G and flame surface density Σ useful in applications could be considered superfluous from the theoretical viewpoint.
The representation of surprise in English and the retroactive construction of possible paths
Authors: Ranger Graham
Published: October 2019

The current article considers the linguistic representation of surprise in English within the framework of the Theory of Enunciative and Predicative Operations. English appears not to have any markers specialised in the expression of surprise. Here I argue that English does nonetheless possess numerous formal configurations which may be shown to derive from a recurrent schema of surprise. I consider three such configurations: the concessive YET, OF ALL + plural noun and ONLY TO + verb in narrative context. Each configuration mobilises an abstract schema involving a discontinuity between an anticipated situation and an actual situation, i.e. an opposition between a – retroactively re-constructed – virtual class of expected possibilities and a validated occurrence.
‘Hakken en plakken’
Authors: Dols-Koot Ilona J. E. , van Rijt Jimmy H. M.
Published: October 2019

Orthography is considered to be a major problem in Dutch education, since many pupils don’t seem to be able to
master orthographic rules, even after years of education. In educational literature it is argued that the problems related to
spelling are caused by approaches that focus more on rules of thumb than on linguistic insights. This is somewhat remarkable,
since a good understanding of the Dutch orthographic system requires a fair amount of morphological knowledge. In order to
effectively implement this knowledge, the development of a morphological awareness (MA) seems to be required. Therefore, a short
intervention was designed for the upper levels of secondary schools (4 havo) which aimed to foster MA and, subsequently, improve
orthographic skills. Results of this quasi-experimental study indicate that a short intervention can significantly boost MA, but
that students don’t seem to be able to use MA effectively to enhance spelling performance.
How users find their way in hospitals
Authors: Silva Smythe Kelli C. A.
Published: October 2019

This paper presents a study about the information behaviour of users during spatial orientation in a hospital in Brazil. The theoretical basis of the study draws on wayfinding processes, spatial cognition and aspects of human information behaviour. Moreover, the case study reported employed thewib-methodology. The results point out the main behavioural strategies employed by users when finding their way in a hospital, and the information barriers related to the signage and the elements of the built environment. The results ratify the need for a human centred design approach so as to develop effective wayfinding design solutions.
La complexité dans les relations de langues collatérales
Authors: Eloy Jean-Michel
Published: October 2019

In the matter of language, without talking about multiplicity of languages – let’s leave it for a moment –, there is a tension between unity and multiplicity which still deserves to be analised.

The multiple approaches or facets of that we talk have given rise to the multiple fields of linguistics, the multiple ‘sciences of language’. This term, in plural, has been adopted in France by scientific policies, by a kind of renunciation of the singular language. Of course, the necessary specializations determine institutional territories that are keen to distinguish themselves, but does it imply the impossibility of a one science of language?

These multiple approaches are opposed to the intuition we have of the unity of the phenomenon: what we singularly call the language, both in the academic world and in the profane. Considering all these facets as legitimate, embracing this multiplicity is a permanent challenge for those who try to com-prehend, in the meaning of ‘grasping together’
The persistence of ‘old language’ and the structuring of language communities
Authors: Feliu Francesc
Published: October 2019

Beyond the foreseen norms of each language, in the legitimization of the facts of language, we intuit that the historical factor is fundamental, not necessarily ratified by the academy or by the culture elites. The perception that an “incorrect” or “not much correct” thing can be said (with the necessary nuances of place and opportunity) because it has an historical base that the legitimates it is very widespread among the speakers. In fact, of a certain persistence of the ancient language largely depends the idea of language as a timeless fact, the awareness of the linguistic territory extension and, in short, the cohesion of linguistic communities – especially those who do not have other political or administrative mechanisms to “remember” the common dimension.
The lowest common denominator as a factor in the formation of Modern Hebrew phonology
Authors: Schwarzwald Ora R.
Published: October 2019

Spoken Hebrew was revived in speech some 140 years ago. Basic classical Hebrew vocabulary and grammatical structures were retained in their language because Jews had always used Hebrew for liturgical purposes and as a means of communicating between disparate communities. However, the mother tongues used by Jews from different communities and their societal status affected their pronunciation. The phonological structure of Modern Hebrew reflects the lowest common denominator of the language traditions of these early speakers. Some biblical phonemes disappeared from use, allophones turned into phonemes, consonant clusters deviated from the classical language, and loan consonants and unexpected stress patterns entered the phonological system.
Contribuciones de Joan Coromines y Jakob Jud a la dialectología de las lenguas románicas
Authors: Araya Méndez Johan
Published: October 2019

At the start of the 20th century, the theoretical and methodological approaches to the study of dialectology were innovated, among other things, by the principles of linguistic geography whose founder is Jules Gilliéron. This article will discuss some aspects which demonstrate how Jakob Jud assimilated and improved the principles of this new way of studying the linguistic diversity of a determined territory. At the same time, this work intends to analyse some items of importance about the epistolary correspondence between Jud and Joan Coromines, who was his student and one of the most well-known linguists of that century. The study approaches used by the two linguists for questioning the dialect speakers will also be analysed in this article along with the works of Jud and Coromines as an example model. That will allow us a better comprehension of the diversity of the linguistic of roman languages.