bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of noise components on L-shaped and T-shaped heterojunction tunnel field effect transistors
Authors: Chander Sweta , Sinha Sanjeet Kumar , Chaudhary Rekha , Goswami Rupam 
Published: April 2022

Abstract
This paper reports on a comparative study of the analysis of electrical noise of heterojunction tunnelling-field-effect-transistors with an L-shaped gate (LTFET) and with a T-shaped gate (TTFET) using numerical simulations. The effect of different noise components on both structures were investigated at low frequency and high frequency to check the viability of the proposed devices. The two source regions are used in TTFET to increase the tunnelling area that enhances the ON-current. Also, we studied the effect of introducing Gaussian traps onto the interface of the source-gate oxide and channel-gate oxide on different noise components and net noise. TTFET outperforms LTFET in terms of electrical parameters and noise spectral densities, thereby offering a solution to the trade-off between high tunnelling rates and noise spectral densities in TFETs. The proposed LTFET and TTFETs are free from ambipolarity issues and can further be deployed in low power applications.
GaN based trigate HEMT with AlGaN back-barrier layer: proposal and investigation
Authors: Verma Manish , Nandi Ashutosh 
Published: April 2022

Abstract
In the present work, we have proposed a GaN based trigate high electron mobility transistor with AlGaN back-barrier (BB) layer that effectively suppress the punch-through effects as compared to the conventional device without BB layer. Furthermore, the device performance of the proposed structure has been studied by varying the distance (t
ch) between AlGaN (barrier)/GaN (channel) to AlGaN (BB)/GaN (channel) interface from 100 nm to 500 nm. It is observed that the optimization of barrier/channel to BB/channel distance (t
ch) is beneficial for minimizing the off-state leakage current and thereby, a high ON/OFF ratio (∼108) and nearly ideal subthreshold slope (∼64–66 mV decade−1) is achieved. Subsequently, it is shown that the optimized distance of t
ch = 300 nm results in superior breakdown voltage (∼198 V) and cut-off frequency (∼81 GHz), leading to excellent Johnson figure-of-merit. The proposed device promises great potential for use in next generations high-power microwave applications.
Delamination model of an epoxy-impregnated REBCO superconducting pancake winding
Authors: Gao Peifeng , Pan Yingzheng 
Published: April 2022

Abstract
Rare-earth barium copper oxide (REBCO) coated conductor (CC) tapes are promising for high-energy and high-field applications. In epoxy-impregnated REBCO superconducting windings, during the cooling process, the delamination induced by thermal mismatch stress significantly threatens stable operation due to the weak c-axial strength of REBCO CC tapes. In this study, a two-dimensional axisymmetric multilayer delamination finite element model with main layers of REBCO CC tapes and insulation materials was developed based on the bilinear cohesive zone model. Based on the proposed model, the stress distribution and delamination properties of an epoxy-impregnated REBCO winding induced during the cooling process were investigated. Furthermore, the effects on the structural configuration on the delamination and optimisation schemes of fabrication are discussed. The model results indicate that during the cooling process of the REBCO winding, when the radial tensile stress induced by the thermal mismatch stress is greater than the delamination strength, interface cracking will occur. Interface failure occurs in regions containing several turns of coils and not just a single-turn coil. Our analyses indicate that structural failure caused by delamination depends on the radius ratio of the outer to the inner winding, where a small radius ratio is preferred to reduce the risk of delamination. An excessive radius ratio can result in multiple delamination failures during the cooling process. The optimisation scheme, which divides the winding into several sub-windings with a consistently small radius ratio, is an effective method for mitigating the risk of delamination failure, which is consistent with available experimental results. Additionally, by reducing the thermal expansion coefficient of the epoxy resin, the risk of delamination failure during cooling can be significantly reduced. For the winding structure considered in this study, if the coefficient of thermal expansion of the epoxy resin is reduced to 5 (

×

10
6

K−1), then delamination failure caused by thermal mismatch will be eliminated. Our model results are consistent with those of several valuable experimental phenomena and numerical calculated in the literature.
Geometric quantum speed limits for Markovian dynamics in open quantum systems
Authors: Lan Kang , Xie Shijie , Cai Xiangji 
Published: April 2022

Abstract
We study theoretically the geometric quantum speed limits (QSLs) of open quantum systems under Markovian dynamical evolution. Three types of QSL time bounds are introduced based on the geometric inequality associated with the dynamical evolution from an initial state to a final state. By illustrating three types of QSL bounds at the cases of presence or absence of system driving, we demonstrate that the unitary part, dominated by system Hamiltonian, supplies the internal motivation for a Markovian evolution which deviates from its geodesic. Specifically, in the case of unsaturated QSL bounds, the parameters of the system Hamiltonian serve as the eigen-frequency of the oscillations of geodesic distance in the time domain and, on the other hand, drive a further evolution of an open quantum system in a given time period due to its significant contribution in dynamical speedup. We present physical pictures of both saturated and unsaturated QSLs of Markovian dynamics by means of the dynamical evolution trajectories in the Bloch sphere which demonstrates the significant role of system Hamiltonian even in the case of initial mixed states. It is further indicated that whether the QSL bound is saturated is ruled by the commutator between the Hamiltonian and reduced density matrix of the quantum system. Our study provides a detailed description of QSL times and reveals the effects of system Hamiltonian on the unsaturation of QSL bounds under Markovian evolution.
Analytical study on magnetic component of geodesic acoustic mode
Authors: Xie Baoyi , Ye Lei , Chen Yang , Zhao Pengfei , Guo Wenfeng , Xiang Nong 
Published: April 2022

Abstract
To understand the role of geodesic acoustic modes (GAMs) in regulating the transport by interacting with background electromagnetic turbulence, a thorough theoretical understanding of the magnetic components of the mode is required. In this study, the magnetic components of GAM are analytically investigated under the gyrokinetic framework with both the

m
=
1

and

m
=
2

harmonics are considered, where

m

is the poloidal mode number. With the quasi-neutrality condition and Ampère’s law, the amplitudes of various poloidal magnetic components are derived. It is shown that both

m
=
1

and

m
=
2

magnetic components exist and are dominated by the cosine and sine components, respectively. In addition, it is found that the amplitudes of all magnetic components increase with respect to the ratio of plasma pressure to magnetic pressure

β

and safety factor

q
.

Most importantly, the amplitude of

m
=
1

magnetic component is significantly enhanced due to the coupling of magnetic drift frequency with the first and second harmonics of the distribution functions, thus it can be comparable to that of

m
=
2

magnetic component under certain conditions. The various magnetic components derived in this study may provide some guidance for experimental measurements.
Synthesis and characterization of nanoparticles of semiconducting metal suplhide and their application
Authors: Darekar Madhavi Sharad , Praveen B M 
Published: April 2022

Abstract
Cadmium Sulphide (CdS) [II-VI group n-type semiconductor] and Copper Sulphide (Cu2S) [I-VI group p-type semiconductor] have large commercial applications like solar cell, gas sensor etc. Wide band gap CdS semiconductor was used as the transparent window material together with narrow band gap Cu2S semiconductor used as the absorber layer. Thioglycerol capped CdS and Cu2S nanoparticles were synthesized by using the non-aqueous chemical method at room temperature. CdS and Cu2S films were prepared on fluorine doped tin oxide (FTO) glass substrates by using the simple dip coating method at different dip times and heat treated in air. CdS and Cu2S nanoparticles were analysed by Ultraviolet-Visible absorption spectroscopy, photoluminescence (PL) and transmission electron microscopy (TEM). CdS and Cu2S films were investigated by scanning electron microscopy (SEM), energy dispersive analysis by x-rays (EDAX), mapping and atomic force microscopy (AFM). Thicknesses of films were determined using laser profilometer. Previously, preparation of solar cells using CdS and Cu2S films deposited by dip coating method has not been reported. In this study, thin-film solar cells with p-n heterojunction having enhanced conductivity, excellent solar energy conversion efficiency, enhanced fill factor, low cost and easy fabrication were prepared to increase the quality of solar cells.
Improving constraints on the reionization parameters using 21-cm bispectrum
Authors: Tiwari Himanshu , Shaw Abinash Kumar , Majumdar Suman , Kamran Mohd , Choudhury Madhurima 
Published: April 2022

Abstract
Radio interferometric experiments aim to constrain the reionization model parameters by measuring the 21-cm signal statistics, primarily the power spectrum. However the Epoch of Reionization (EoR) 21-cm signal is highly non-Gaussian, and this non-Gaussianity encodes important information about this era. The bispectrum is the lowest order statistic able to capture this inherent non-Gaussianity. Here we are the first to demonstrate that bispectra for large and intermediate length scales and for all unique k-triangle shapes provide tighter constraints on the EoR parameters compared to the power spectrum or the bispectra for a limited number of shapes of k-triangles. We use the Bayesian inference technique to constrain EoR parameters. We have also developed an Artificial Neural Network (ANN) based emulator for the EoR 21-cm power spectrum and bispectrum which we use to remarkably speed up our parameter inference pipeline. Here we have considered the sample variance and the system noise uncertainties corresponding to 1000 hrs of SKA-Low observations for estimating errors in the signal statistics. We find that using all unique k-triangle bispectra improves the constraints on parameters by a factor of 2 – 4 (depending on the stage of reionization) over the constraints that are obtained using power spectrum alone.
Breaking baryon-cosmology degeneracy with the electron density power spectrum
Authors: Nicola Andrina , Villaescusa-Navarro Francisco , Spergel David N. , Dunkley Jo , Anglés-Alcázar Daniel , Davé Romeel , Genel Shy , Hernquist Lars , Nagai Daisuke , Somerville Rachel S. , Wandelt Benjamin D. 
Published: April 2022

Abstract
Uncertain feedback processes in galaxies affect the distribution of matter, currently limiting the power of weak lensing surveys.
If we can identify cosmological statistics that are robust against these uncertainties, or constrain these effects by other means, then we can enhance the power of current and upcoming observations from weak lensing surveys such as DES, Euclid, the Rubin Observatory, and the Roman Space Telescope. In this work, we investigate the potential of the electron density auto-power spectrum as a robust probe of cosmology and baryonic feedback. We use a suite of (magneto-)hydrodynamic simulations from the CAMELS project and perform an idealized analysis to forecast statistical uncertainties on a limited set of cosmological and physically-motivated astrophysical parameters. We find that the electron number density auto-correlation, measurable through either kinematic Sunyaev-Zel'dovich observations or through Fast Radio Burst dispersion measures, provides tight constraints on Ω
m
and the mean baryon fraction in intermediate-mass halos, f̅
bar. By obtaining an empirical measure for the associated systematic uncertainties, we find these constraints to be largely robust to differences in baryonic feedback models implemented in hydrodynamic simulations. We further discuss the main caveats associated with our analysis, and point out possible directions for future work.
Image Desaturation for SDO/AIA Using Mixed Convolution Network
Authors: Yu Xuexin , Xu Long , Ren Zhixiang , Zhao Dong , Sun Wenqing 
Published: April 2022

Abstract
The Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) provides full-disk solar images with high temporal cadence and spatial resolution over seven extreme ultraviolet (EUV) wave bands. However, as violent solar flares happen, images captured in EUV wave bands may have saturation in active regions, resulting in signal loss. In this paper, we propose a deep learning model to restore the lost signal in saturated regions by referring to both unsaturated/normal regions within a solar image and statistical probability model of massive normal solar images. The proposed model, namely mixed convolution network (MCNet), is established over conditional generative adversarial network (GAN) and the combination of partial convolution (PC) and validness migratable convolution (VMC). These two convolutions were originally proposed for image inpainting. In addition, they are implemented only on unsaturated/valid pixels, followed by certain compensation to compensate the deviation of PC/VMC relative to normal convolution. Experimental results demonstrate that the proposed MCNet achieves favorable desaturated results for solar images and outperforms the state-of-the-art methods both quantitatively and qualitatively.
Operation and performance of a dual-phase crystalline/vapor xenon time projection chamber
Authors: Kravitz S. , Chen H. , Gibbons R. , Haselschwardt S.J. , Xia Q. , Sorensen P. 
Published: April 2022

Abstract
We have built and operated a crystalline/vapor xenon TPC, with the goal of improving searches for dark matter. The motivation for this instrument is the fact that beta decays from the radon decay chain to the ground state presently limit the state-of-the-art liquid/vapor xenon experiments. In contrast, a crystalline xenon target has the potential to exclude, or tag and reject radon-chain backgrounds. As a preamble to demonstrating such capabilities, the present article makes a first demonstration of the operation of a crystalline/vapor xenon TPC with electroluminescence (gas gain) for the electron signal readout. It also shows that the scintillation yield in crystalline xenon appears to be identical to that in liquid xenon, in contrast to previous results.
The influence of land-use activities and regional drought on historical fire regimes of Buryatia, Siberia
Authors: Bigio Erica R , Swetnam Thomas W , Baisan Christopher H , Guiterman Christopher H , Kisilyakhov Yegor K , Andreev Sergey G , Batotsyrenov Eduard A , Ayurzhanaev Alexander A 
Published: April 2022

Abstract
Every year, millions of hectares burn across Siberia, driven by a combination of warming temperatures, regional drought and human-caused ignitions. Dendrochronology provides a long-term context to evaluate recent trends in fire activity and interpret the relative influence of humans and climate drivers on fire regimes. We developed a 400 year record of fire-scarred trees from 17 sites in pine-dominated forests located southeast of Lake Baikal. Site-level mean fire return intervals (MFIs) ranged from 4 to 27 years for all fires and 8 to 35 years for widespread fires within sites. Sites with the lowest MFI values were located within 1 km of agricultural fields in grassland valleys, suggesting that agricultural burning influenced MFIs at nearby sites. Fire frequency varied over the record, with significantly high values around 1790, from 1865 to 1880, 1948 to 1955 and 1995 to 2005. The increased fire activity corresponded with migration waves to the region and major socio-economic change connected with the establishment and breakdown of the Soviet Union. At broader scales, superposed epoch analysis showed that synchronous fire years were associated with regional drought and precipitation deficits. Wet conditions for 2–3 years prior to the event year were also significant, suggesting that increased moisture promoted growth of understory fine fuels to support more extensive fires across the study area. Although fire frequencies increased during the 20th century, fire–climate relationships weakened, suggesting increased human-caused ignitions may override regional climate drivers. Our dataset presents a continuous record of frequent surface fires over the past 400 years, providing a valuable opportunity to compare dendrochronology-based reconstructions with satellite and documentary records.
Time-series maps reveal widespread change in plant functional type cover across Arctic and boreal Alaska and Yukon
Authors: Macander Matthew J , Nelson Peter R , Nawrocki Timm W , Frost Gerald V , Orndahl Kathleen M , Palm Eric C , Wells Aaron F , Goetz Scott J 
Published: April 2022

Abstract
Widespread changes in the distribution and abundance of plant functional types (PFTs) are occurring in Arctic and boreal ecosystems due to the intensification of disturbances, such as fire, and climate-driven vegetation dynamics, such as tundra shrub expansion. To understand how these changes affect boreal and tundra ecosystems, we need to first quantify change for multiple PFTs across recent years. While landscape patches are generally composed of a mixture of PFTs, most previous moderate resolution (30 m) remote sensing analyses have mapped vegetation distribution and change within land cover categories that are based on the dominant PFT; or else the continuous distribution of one or a few PFTs, but for a single point in time. Here we map a 35 year time-series (1985–2020) of top cover (TC) for seven PFTs across a 1.77 × 106 km2 study area in northern and central Alaska and northwestern Canada. We improve on previous methods of detecting vegetation change by modeling TC, a continuous measure of plant abundance. The PFTs collectively include all vascular plants within the study area as well as light macrolichens, a nonvascular class of high importance to caribou management. We identified net increases in deciduous shrubs (66 × 103 km2), evergreen shrubs (20 × 103 km2), broadleaf trees (17 × 103 km2), and conifer trees (16 × 103 km2), and net decreases in graminoids (−40 × 103 km2) and light macrolichens (−13 × 103 km2) over the full map area, with similar patterns across Arctic, oroarctic, and boreal bioclimatic zones. Model performance was assessed using spatially blocked, nested five-fold cross-validation with overall root mean square errors ranging from 8.3% to 19.0%. Most net change occurred as succession or plant expansion within areas undisturbed by recent fire, though PFT TC change also clearly resulted from fire disturbance. These maps have important applications for assessment of surface energy budgets, permafrost changes, nutrient cycling, and wildlife management and movement analysis.
Coupled insights from the palaeoenvironmental, historical and archaeological archives to support social-ecological resilience and the sustainable development goals
Authors: Allen K J , Reide F , Gouramanis C , Keenan B , Stoffel M , Hu A , Ionita M 
Published: April 2022

AbstractMany governments and organisations are currently aligning many aspects of their policies and practices to the sustainable development goals (SDGs). Achieving the SDGs should increase social-ecological resilience to shocks like climate change and its impacts. Here, we consider the relationship amongst the three elements—the SDGs, social-ecological resilience and climate change—as a positive feedback loop. We argue that long-term memory encoded in historical, archaeological and related ‘palaeo-data’ is central to understanding each of these elements of the feedback loop, especially when long-term fluctuations are inherent in social-ecological systems and their responses to abrupt change. Yet, there is scant reference to the valuable contribution that can be made by these data from the past in the SDGs or their targets and indicators. The historical and archaeological records emphasise the importance of some key themes running through the SDGs including how diversity, inclusion, learning and innovation can reduce vulnerability to abrupt change, and the role of connectivity. Using paleo-data, we demonstrate how changes in the extent of water-related ecosystems as measured by indicator 6.6.1 may simply be related to natural hydroclimate variability, rather than reflecting actual progress towards Target 6.6. This highlights issues associated with using SDG indicator baselines predicated on short-term and very recent data only. Within the context of the contributions from long-term data to inform the positive feedback loop, we ask whether our current inability to substantively combat anthropogenic climate change threatens achieving both the SDGS and enhanced resilience to climate change itself. We argue that long-term records are central to understanding how and what will improve resilience and enhance our ability to both mitigate and adapt to climate change. However, for uptake of these data to occur, improved understanding of their quality and potential by policymakers and managers is required.
Tuning quantum–classical correspondence for atomic and molecular systems in a cavity
Authors: Moiseyev Nimrod , Šindelka Milan 
Published: April 2022

Abstract
We show that the correspondence between quantum and classical mechanics can be tuned by varying the coupling strength between an atom or a molecule and the modes of a cavity. In the acceleration gauge (AG) representation, the cavity–matter system is described by an effective Hamiltonian, with a non-trivial coupling appearing in the potential, and with renormalized masses. Importantly, and counterintuitively, the AG coupling changes non-monotonically with the strength of the cavity–matter interaction. As a result, one obtains an effective (approximately decoupled) cavity–matter dynamics both for the case of weak and strong interactions. In the weak coupling regime, the effective mass parameters essentially coincide with their standard interaction free counterparts. In contrast, the renormalized atomic/molecular mass increases as the cavity–matter interaction is increased. This results in AG dynamics of matter governed by a conventionally looking atomic/molecular Hamiltonian, whose effective Planck constant is reduced when the cavity–matter interaction is increased.
Localization of space-inhomogeneous three-state quantum walks
Authors: Kiumi Chusei 
Published: April 2022

Abstract
Mathematical analysis on the existence of eigenvalues is essential because it is deeply related to localization, which is an exceptionally crucial property of quantum walks (QWs). We construct the method for the eigenvalue problem via the transfer matrix for space-inhomogeneous three-state QWs in one dimension with a self-loop, which is an extension of the technique in a previous study (Kiumi and Saito 2021 Quantum Inf. Process.
20 171). This method reveals the necessary and sufficient condition for the eigenvalue problem of a two-phase three-state QW with one defect whose time evolution varies in the negative part, positive part, and at the origin.