bluuebunny/crossref_metadata_2025 huggingface dataset:
On the identification and assessment of underlying acoustic dimensions of soundscapes
Authors: Bergner Jakob , Peissig Jürgen
Published: October 2022

The concept of soundscapes according to ISO 12913-1/-2/-3 proposes a descriptive framework based on a triangulation between the entities acoustic environment, person and context. While research on the person-related dimensions is well established, there is not yet complete agreement on the relevant indicators and dimensions for the pure description of acoustic environments. Therefore, this work attempts to identify acoustic dimensions that actually vary between different acoustic environments and thus can be used to characterize them. To this end, an exploratory, data-based approach was taken. A database of Ambisonics soundscape recordings (approx. 12.5 h) was first analyzed using a variety of signal-based acoustic indicators (Ni = 326) within the categories loudness, quality, spaciousness and time. Multivariate statistical methods were then applied to identify compound and interpretable acoustic dimensions. The interpretation of the results reveals 8 independent dimensions “Loudness”, “Directivity”, “Timbre”, “High-Frequency Timbre”, “Dynamic Range”, “High-Frequency Amplitude Modulation”, “Loudness Progression” and “Mid-High-Frequency Amplitude Modulation” to be statistically relevant. These derived latent acoustic dimensions explain 48.76% of the observed total variance and form a physical basis for the description of acoustic environments. Although all baseline indicators were selected for perceptual reasons, validation must be done through appropriate listening tests in future.
Structure of optimal control for planetary landing with control and state constraints
Authors: Leparoux Clara , Hérissé Bruno , Jean Frédéric
Published: October 2022

This paper studies a vertical powered descent problem in the context of planetary landing, considering glide-slope and thrust pointing constraints and minimizing any final cost. In a first time, it proves the Max-Min-Max or Max-Singular-Max form of the optimal control using the Pontryagin Maximum Principle, and it extends this result to a problem formulation considering the effect of an atmosphere. It also shows that the singular structure does not appear in generic cases. In a second time, it theoretically analyzes the optimal trajectory for a more specific problem formulation to show that there can be at most one contact or boundary interval with the state constraint on each Max or Min arc.
Association Of Blood Lipocalin-2 Levels with Gestational Diabetes Mellitus: A Systematic Review and Meta-Analysis
Authors: Zhu Jing , Jiang Shuai , Jiang Xiaohong , Luo Kaiming , Huang Xiaolin , Hua Fei
Published: October 2022

Lipocalin-2 (LCN2) is becoming recognized as a pleiotropic mediator of metabolic disorders. However, the relationship between LCN2 and gestational diabetes mellitus (GDM) is not well understood. We performed a systematic review and meta-analysis to explore it. A systematic search of Cochrane Library, PubMed, Embase, Scopus, Web of Science, Chinese National Knowledge Infrastructure, and Wan-fang Database was done for relevant articles published up to September 29, 2021. Standardized mean difference (SMD) with 95% confidence intervals (CI) was calculated to explore the association of LCN2 levels with GDM using Revman 5.3 and Stata 15.1. Fifteen case-control studies were included in this meta-analysis. The patients with GDM had significantly higher levels of blood LCN2 than parturients with normal glucose tolerance (SMD=3.41, 95% CI=2.24 to 4.58). Meta-regression and subgroup analysis were conducted to investigate the source of heterogeneity. Likely sources of heterogeneity were age and testing methods. This study found that GDM showed higher blood LCN2 levels than controls. However, caution is warranted on the interpretation of these findings. Standardized LCN2 measurement methods and longitudinal studies are required to disentangle and better understand the relationships observed.
Easy Access to N-(Pyridin-2-yl)benzamides through Electro-oxidative Ring Opening of 2-Arylimidazo[1,2-a]pyridines
Authors: Ghosh Sayan , Dutta Jhilik , De Sarkar Suman , Halder Atreyee
Published: October 2022

An electro-oxidative method for the ring opening of imidazopyridine derivatives is reported. This mild protocol offers a sustainable alternative to the existing harsh reaction conditions and unleashes an efficient approach to produce N-(pyridin-2-yl)amide derivatives with good tolerance of different functional groups. Systematic mechanistic studies provided insight into the reaction pathway and revealed that the residual water of DMSO is the source of oxygen atoms in the products.
Reaction Mechanisms for Chiral-Phosphate-Catalyzed Transformations Involving Cationic Intermediates and Protic Nucleophiles
Authors: Reid Jolene P. , Zhai Jianyu
Published: October 2022

Recent strategies for enantioinduction often focus on employing a chiral catalyst to noncovalently interact with the substrate. By restricting the number of low energy diastereomeric transition states the reacting components can adopt, stereoselectivity can be achieved. Many of these noncovalent interactions include a significant dispersive component and these types of contacts have historically been difficult to model accurately. Modern computational methods have been designed to overcome such limitations. Using our computational work on chiral phosphate catalysis, we discuss the reasons for enantioselectivity in diverse reaction space.

1 Introduction

2 Chiral Phosphate Catalysis

3 Phosphate-Catalyzed Transfer Hydrogenation

4 Phosphate-Catalyzed Aza-Friedel–Crafts Reaction

5 Phosphate-Catalyzed Reactions Involving Allenamides

6 Comprehensive Qualitative Models

7 Chiral Phosphates and Thionium Intermediates

8 Conclusion
Fronto-Temporo-Orbito-Zygomatic Approach with Orbital Reconstruction in Lesions causing Unilateral Non-pulsating Proptosis
Authors: Darwish Mohab , Moawad Ahmed
Published: October 2022

Background Unilateral non-pulsating proptosis can be caused by lesions with intraorbital extensions compressing the globe including sphenoid wing en plaque meningiomas and paranasal sinuses lesions.

Patients and Methods We operated on 20 patients with unilateral non-pulsating proptosis using fronto-temporo-orbito-zygomatic (FTOZ) approach with orbital reconstruction in six patients. Eighteen patients had sphenoid wing en plaque meningioma, 1 patient had paranasal sinuses fungal infection with intraorbital and intracranial extension, and 1 patient had frontal sinus dermoid with intraorbital extension.

Results Proptosis was corrected in 50% of the patients, improved in 25%, and remained stationary in 25%. Vision improved in three patients, remained stationary in three, and deteriorated in one patient. Two patients had temporary oculomotor ophthalmoplegia that resolved within 3 months.

Conclusion Although it is an invasive approach, FTOZ gives excellent exposure of the orbit and anterolateral skull base that allows the excision of intracranial lesions with orbital extension. If needed, the orbit could be reconstructed easily due to excellent exposure.
Use of Wrist Denervation in the Treatment of SLAC and SNAC Wrist by ASSH Members
Authors: Kale Nisha N. , Foote Jake , Medvedev Gleb
Published: October 2022

Background Scapholunate advanced collapse (SLAC) and scaphoid nonunion advanced collapse (SNAC) are common patterns of wrist arthritis, and surgical treatment options include partial and total wrist arthrodesis and wrist denervation, which maintains the current anatomy while relieving pain.

Introduction The purpose of this study is to elucidate current practices within the hand surgery community with respect to the use of anterior interosseous nerve/posterior interosseous nerve (AIN/PIN) denervation in the treatment of SLAC and SNAC wrists.

Methods An anonymous survey was distributed to 3,915 orthopaedic surgeons via the American Society for Surgery of the Hand (ASSH) listserv. The survey collected information on conservative and operative management, indications, complications, diagnostic block, and coding of wrist denervation.

Results In total, 298 answered the survey. 46.3% (N = 138) of the respondents used denervation of AIN/PIN for every SNAC stage, and 47.7% (N = 142) of the respondents used denervation of AIN/PIN for every SLAC wrist stage. AIN and PIN combined denervation was the most common standalone procedure (N = 185, 62.1%). Surgeons were more likely to offer the procedure (N = 133, 55.4%) if motion preservation had to be maximized (N = 154, 64.4%). The majority of surgeons did not consider loss of proprioception (N = 224, 84.2%) or diminished protective reflex (N = 246, 92.1%) to be significant complications. 33.5%, 90 respondents reported never performing a diagnostic block prior to denervation.

Conclusion Both SLAC and SNAC patterns of wrist arthritis can result in debilitating wrist pain. There is a wide range of treatment for different stages of disease. Further investigation is required to identify ideal candidates and evaluate long-term outcomes.
When health is wealth: occupationally differentiated patterns of health capital in post-industrial Europe
Authors: Harsløf Ivan , Larsen Kristian , Bambra Clare
Published: October 2022

This paper explores the general relationship between peoples’ health-related practices and their affiliation with different fields in the occupational structure. It argues that ‘healthy behaviour’ may be particularly induced in the field of service occupations (jobs where one is providing a service, rather than producing a physical product), rendering such practices an emerging capital in the sense advanced by Bourdieu. The paper presents an empirical elaboration of this theoretical argument by assessing comparative European data on health behavioural dispositions. Across occupational class levels, defined according to Esping-Andersen’s post-industrial class scheme, service workers display dispositions suggesting greater possessions of health capital than their counterparts in the industrial hierarchy. In a multilevel analysis, considering societal context, the paper furthermore associates such endowments with post-industrial development. Elaborating on the general relationships identified, we suggest the rising importance of individual health investments to be considered as potentially instigating and reinforcing symbolic boundaries (social closure).
Impact of social determinants on COVID-19 infections: a comprehensive study from Saudi Arabia governorates
Authors: Yaseen Abdallah S. A.
Published: October 2022

The last two years have been marked by the emergence of Coronavirus. The pandemic has spread in most countries, causing substantial changes all over the world. Many studies sought to analyze phenomena related to the pandemic from different perspectives. This study analyzes data from the governorates of the Kingdom of Saudi Arabia (the KSA), proposing a broad analysis that addresses three different research objectives. The first is to identify the main factors affecting the variations between KSA governorates in the cumulative number of COVID-19 infections. The study uses principal component regression. Results highlight the significant positive effects of the number of schools in each governorate, and classroom density within each school on the number of infections in the KSA. The second aim of this study is to use the number of COVID-19 infections, in addition to its significant predictors, to classify KSA governorates using the K-mean cluster method. Findings show that all KSA governorates can be grouped into two clusters. The first cluster includes 31 governorates that can be considered at greater risk of Covid infections as they have higher values in all the significant determinants of Covid infections. The last objective is to compare between traditional statistical methods and artificial intelligence techniques in predicting the future number of COVID-19 infections, with the aim of determining the method that provides the highest accuracy. Results also show that multilayer perceptron neural network outperforms others in forecasting the future number of COVID-19. Finally, the future number of infections for each cluster is predicted using multilayer perceptron neural network method.
Reconstructing makerspaces in China: mass innovation space and the transformative creative industries
Authors: Fu Pengfei , Li Lin , Xie Xuefang
Published: October 2022

In recent years, the makerspaces and so-called “mass innovation spaces” (MISs) in China have been under heavy scholarly investigation. However, despite the proliferation of MISs and growing interest in understanding this phenomenon, the definition of MIS has also been a concern in this field. Meanwhile, there has also been a tendency to link these reconstructed MISs with the development agenda of the local creative industries. What is an MIS, and how is it similar and different from the general understanding of makerspaces in the context of China? What can we learn from China’s adoption and appropriation of MISs in relation to the transformation of creative industries? To answer these questions, we conducted a semantic network analysis of the mission statements from 305 Chinese MISs. The results show that the Chinese MIS is quite different from the makerspace in terms of space, activities, values, philosophy, community, and organization. By examining the reconstructed MISs, this article provides some examples of how the Western, Californian ideology-centered concept of “makerspace” is repurposed as a new site with many alternative imaginaries that are interwoven with what we term “Shenzhen ideology”—a mix of socialism and technological determinism and a fusion of social conservatism and economic progressivism.
Broadband and low-frequency sound absorption of modified Helmholtz resonator combined with porous layer addition
Authors: Vergara E. F. , Almeida G. N. , Barbosa L. R. , Lenzi A. , Carvalho de Sousa A.
Published: October 2022

In this work, a hybrid acoustic material (HAM) is designed for broadband and low-frequency sound absorption based on the combination of two different materials: a porous layer (melamine foam) and a modified Helmholtz resonator with embedded necks (HRENs). Theoretical predictions, numerical simulations, and experimental measurements are conducted to investigate the acoustic characteristics of the HREN. The HAM absorption mechanism is presented to evaluate the broadband sound absorption by the impedance matching effect of the different structures. The results of experimental tests confirmed that the HAM has broadband sound absorption and presented good agreement with an equivalent fluid model and numerical simulations. Broadband sound absorption was comparatively evaluated by the broadband factor (Qα), revealing the advantages due to the possible configurations of HAM in relation to HREN and melamine foam. In addition, the selection and dimensions of the HREN holes and the perforation ratio, in the range of 3%–10%, allow the hybrid sound absorber to achieve one absorption peak between 235 and 582 Hz with quasi-total absorption (α≥0.8). This work contributes to the understanding of sound wave propagation and broadband absorption in acoustic materials composed of different materials combined.
Multistability and evolution of chimera states in a network of type II Morris–Lecar neurons with asymmetrical nonlocal inhibitory connections
Authors: Dogonasheva O. , Kasatkin Dmitry , Gutkin Boris , Zakharov Denis
Published: October 2022

Formation of synchronous activity patterns is an essential property of neuronal networks that has been of central interest to synchronization theory. Chimera states, where both synchronous and asynchronous activities of neurons co-exist in a single network, are particularly poignant examples of such patterns, whose dynamics and multistability may underlie brain function, such as cognitive tasks. However, dynamical mechanisms of coherent state formation in spiking neuronal networks as well as ways to control these states remain unclear. In this paper, we take a step in this direction by considering the evolution of chimera states in a network of class II excitable Morris–Lecar neurons with asymmetrical nonlocal inhibitory connections. Using the adaptive coherence measure, we are able to partition the network parameter space into regions of various collective behaviors (antiphase synchronous clusters, traveling waves, different types of chimera states as well as a spiking death regime) and have shown multistability between the various regimes. We track the evolution of the chimera states as a function of changed key network parameters and found transitions between various types of chimera states. We further find that the network can demonstrate long transients leading to quasi-persistence of activity patterns in the border regions hinting at near-criticality behaviors.
Quantitative super-resolution imaging of pathological aggregates reveals distinct toxicity profiles in different synucleinopathies
Authors: Morten Michael J. , Sirvio Liina , Rupawala Huzefa , Mee Hayes Emma , Franco Aitor , Radulescu Carola , Ying Liming , Barnes Samuel J. , Muga Arturo , Ye Yu
Published: October 2022

Protein aggregation is a hallmark of major neurodegenerative disorders. Increasing data suggest that smaller aggregates cause higher toxic response than filamentous aggregates (fibrils). However, the size of small aggregates has challenged their detection within biologically relevant environments. Here, we report approaches to quantitatively super-resolve aggregates in live cells and ex vivo brain tissues. We show that Amytracker 630 (AT630), a commercial aggregate-activated fluorophore, has outstanding photophysical properties that enable super-resolution imaging of α-synuclein, tau, and amyloid-β aggregates, achieving ∼4 nm precision. Applying AT630 toAppNL-G-Fmouse brain tissues or aggregates extracted from a Parkinson’s disease donor, we demonstrate excellent agreement with antibodies specific for amyloid-β or α-synuclein, respectively, confirming the specificity of AT630. Subsequently, we use AT630 to reveal a linear relationship between α-synuclein aggregate size and cellular toxicity and discovered that aggregates smaller than 450 ± 60 nm (aggregate450nm) readily penetrated the plasma membrane. We determine aggregate450nmconcentrations in six Parkinson’s disease and dementia with Lewy bodies donor samples and show that aggregates in different synucleinopathies demonstrate distinct potency in toxicity. We further show that cell-penetrating aggregates are surrounded by proteasomes, which assemble into foci to gradually process aggregates. Our results suggest that the plasma membrane effectively filters out fibrils but is vulnerable to penetration by aggregates of 450 ± 60 nm. Together, our findings present an exciting strategy to determine specificity of aggregate toxicity within heterogeneous samples. Our approach to quantitatively measure these toxic aggregates in biological environments opens possibilities to molecular examinations of disease mechanisms under physiological conditions.
Anthropometric characteristics according to the role performed by World Tour road cyclists for their team
Authors: Sánchez‐Muñoz C. , Mateo‐March M. , Muros J. J. , Javaloyes A. , Zabala M.
Published: October 2022

Certain anthropometric characteristics are required for athletes to successfully perform in elite endurance sports. The present study aims to analyse the anthropometric characteristics of professional cyclists according to their specialty. Anthropometric measurements were conducted of the body composition of 76 male professional road cyclists in line with International Society for Advancement of Kinanthropometry protocol. Fat mass did not differ (p > 0.05) between climbers, all‐rounders and flat specialists, although the following anthropometric variables did differ according to the role played within the team (p < 0.05): Body mass (climbers: 63.8 ± 3.6, all‐rounders: 68.8 ± 5.3, flat specialists: 74.5 ± 5.6 kg) skeletal body mass (climbers: 29.7 ± 1.6, all‐rounders: 31.4 ± 1.9, flat specialists: 33.5 ± 2.4 kg); body surface area (climbers: 1.78 ± 0.07, all‐rounders: 1.89 ± 0.10, flat specialists: 1.96 ± 0.1 m2); frontal area (climbers: 0.33 ± 0.01, all‐rounders: 0.35 ± 0.02, flat specialists: 0.36 ± 0.02 m2). Anthropometric characteristics differ between world‐class cyclists depending on their specialty. These differences could influence performance in relation to different types of road cycling competitions. The present study identified characteristics that could be used by coaches to evaluate their athletes in the context of elite or professional road cycling.
Wald’s entropy in Coincident General Relativity
Authors: Heisenberg Lavinia , Kuhn Simon , Walleghem Laurens
Published: October 2022

The equivalence principle and its universality enables the geometrical formulation of gravity. In the standard formulation of General Relativity (GR) á la Einstein, the gravitational interaction is geometrized in terms of the spacetime curvature. However, if we embrace the geometrical character of gravity, two alternative, though equivalent, formulations of GR emerge in flat spacetimes, in which gravity is fully ascribed either to torsion or to non-metricity. The latter allows a much simpler formulation of GR oblivious to the affine spacetime structure, the Coincident General Relativity (CGR). The entropy of a black hole can be computed using the Euclidean path integral approach, which strongly relies on the addition of boundary or regulating terms in the standard formulation of GR. A more fundamental derivation can be performed using Wald’s formula, in which the entropy is directly related to Noether charges and is applicable to general theories with diffeomorphism invariance. In this work we extend Wald’s Noether charge method for calculating black hole entropy to spacetimes endowed with non-metricity. Using this method, we show that CGR with an improved action principle gives the same entropy as the well-known entropy in standard GR. Furthermore the first law of black hole thermodynamics holds and an explicit expression for the energy appearing in the first law is obtained.
Null and timelike circular orbits from equivalent 2D metrics
Authors: Cunha Pedro V P , Herdeiro Carlos A R , Novo João P A
Published: October 2022

The motion of particles on spherical

1
+
3

dimensional spacetimes can, under some assumptions, be described by the curves on a two-dimensional manifold, the optical and Jacobi manifolds for null and timelike curves, respectively. In this paper we resort to auxiliary two-dimensional metrics to study circular geodesics of generic static, spherically symmetric, and asymptotically flat

1
+
3

dimensional spacetimes, whose functions are at least C
2 smooth. This is done by studying the Gaussian curvature of the bidimensional equivalent manifold as well as the geodesic curvature of circular paths on these. This study considers both null and timelike circular geodesics. The study of null geodesics through the optical manifold retrieves the known result of the number of light rings on the spacetime outside a black hole and on spacetimes with horizonless compact objects. With an equivalent procedure we can formulate a similar theorem on the number of marginally stable timelike circular orbits of a given spacetime satisfying the previously mentioned assumptions.
The stability of galaxies in an expanding Universe obtained by Newtonian dynamics
Authors: Toxvaerd Søren
Published: October 2022

The dynamics of galaxies in an expanding Universe is often determined for gravitational and dark matter in an Einstein-de Sitter Universe, or alternatively by modifying the gravitational long-range attractions in the Newtonian dynamics. Here the time evolution of galaxies is determined by simulations of systems with pure gravitational forces by classical molecular dynamic simulations. A time reversible algorithm for formation and aging of gravitational systems by self-assembly of baryonic objects, recently derived (Toxvaerd 2022Eur. Phys. J. Plus13799), is extended to include the Hubble expansion of the space. The algorithm is stable for billions of time steps without any adjustments. The algorithm is used to simulate simple models of the Milky Way with the Hubble expansion of the Universe, and the galaxies are simulated for times which corresponds to more than 25 Gyr. The rotating galaxies lose bound objects from time to time, but they are still stable at the end of the simulations. The simulations indicate that the explanation for the dynamics of galaxies may be that the Universe is very young in cosmological times. Although the models of the Milky Way are rather stable at 13–14 Gyr, which corresponds to the cosmological time of the Universe, the Hubble expansion will sooner or later release the objects in the galaxies. But the simulations indicate that this will first happen in a far away future.
Thermodynamics of a particle in square well potential
Authors: Bhattacharyya Satadal , Mitra Joydip
Published: October 2022

We have presented the thermodynamic properties of a particle moving freely both in an infinite and finite square well in contact with a heat reservoir at constant temperature. In both cases, we have computed the temperature dependence of the partition function, entropy, average energy and specific heat of the particle in an exact way. The exact results for various thermodynamic parameters deviate considerably from its known theoretical values and reveal the importance of such calculations. The effect of the width of the finite well on the different thermodynamic quantities have also been examined critically.
A fault diagnosis method for rolling bearings based on RDDAN under multivariable working conditions
Authors: Shi Huaitao , Gan Chunxia , Zhang Xiaochen , Meng Weiying , Huang Chengzhuang
Published: October 2022

Mechanical equipment in actual motion can produce noise interference with the vibration signal of rolling bearings, which have non-constant loads and speed. These factors lead to variable and unstable vibration signals of rolling bearings; therefore, it is very difficult to accurately diagnose actual running rolling bearings. In this paper, a residual denoising dynamic adaptation network (RDDAN) is proposed, which uses the signal knowledge under known working conditions to diagnose rolling bearing faults under unknown working conditions. The method mainly consists of data preprocessing, feature extraction, and dynamic distribution adaptation. First, Gaussian noise is added at the data preprocessing stage to emulate the noise perturbation during the reality of rolling bearing operation. Secondly, a deep residual shrinkage network is used for noise reduction and feature extraction. Finally, the marginal probability distribution and conditional probability distribution under different working conditions are calculated, depending on the characteristics. The network is disciplined using the relative weight of the marginal probability distribution and the conditional probability distribution. And the fault classification results are output after multiple iterations. The method was tested on the Case Western Reserve University bearing dataset and the Machine Fault Simulator Magnum bearing dataset, respectively. In comparison with other models, the RDDAN improves the average accuracy by about 23%. The results show that the RDDAN can effectively solve the problem of inconsistent data distribution in rolling bearings under operating conditions influenced by multiple variables such as noise, load, and speed.
An intelligent ultrasonic guided wave deep imaging detection method considering the propagation characteristics of each direction
Authors: Zhang Bin , Chen Zhuyun , Yang Dingmin , Hong Xiaobin , Jin Gang
Published: October 2022

Macroscopic damage in multilayer anisotropic structures is usually formed by the rapid development of material micro-damage. The existing micro-damage imaging detection technology does not consider the difference of wave velocity in all directions of the detection structure, especially not directly taking the wave velocities in different direction into the imaging counting process, the micro-damage imaging detection, and the false detection rate and missed detection rate are high. In this paper, a deep learning imaging detection method considering velocity in all directions is proposed and verified on a carbon fiber anticorrosive coating structure of a shaftless ring propeller drive system. Firstly, the problem that the elliptical damage path cannot be determined in the anisotropic structure is analyzed, and the omnidirectional velocity of the carbon fibre reinforced plastics structure is obtained through simulation analysis. A new omni-directional imaging method was proposed, which discretized the monitored objects and acquired the damage index through deep learning network. The damage propagation time of the reference point was compared with that of the actual damage point to determine the damage probability of the structure. The experimental results show that the omni-directional imaging method can accurately and intuitively display the damage information of anisotropic structures.
Calibration of 3D scan trajectories for an industrial computed tomography setup with 6-DOF object manipulator system using a single sphere
Authors: Butzhammer Lorenz , Müller Andreas Michael , Hausotte Tino
Published: October 2022

In industrial x-ray computed tomography (CT), the application of more complex scan paths in comparison to the typical circular trajectory (360∘rotation of the measurement object) can extend the potential of CT. One way to enable such 3D scan trajectories is to use a 6-degrees-of-freedom (DOF) object manipulator system. In our case, a hexapod is mounted on top of the rotary table of a commercial CT scanner. This allows for adaptive tilting of the measurement object during the scan. For high accuracy, the geometry calibration of such setups is typically done using the x-ray projections of a calibrated multi-sphere object. Contrary to this, here, we demonstrate a procedure that is based on only a single sphere and can therefore experimentally be implemented with low effort. Using the intrinsic geometry parameters of the CT device as prior information, the hexapod coordinate system with respect to the CT machine coordinate system is determined by means of a one-step optimization approach. The resulting parameters are used to calculate projection matrices that enable the volume reconstruction for 3D scan trajectories. The method is validated using simulated x-ray images and experimental investigations including dimensional measurements. For the used setup, geometric measurement results for 3D scan trajectories that are calibrated with the presented method show in sum increased errors compared to the circular scans. A limited pose accuracy of the manipulator system is discussed as a potential cause. The results nevertheless indicate that the presented method is generally feasible for dimensional CT measurements provided that the pose accuracy is sufficient. The calibration procedure can therefore be a low-cost and easier to implement alternative compared to trajectory calibration methods based on multi-sphere objects, but with a tendency towards lower measurement accuracy. The methodology can in principle be transferred to different setups with 6-DOF manipulator systems, e.g. C-arm CT devices with a robot arm.
Numerical modelling for beam duct heat loads calculations and application to the new 1 MW neutral beam injector in the COMPASS tokamak
Authors: Jaulmes F , Zadvitskiy G , Bogar K , Mysiura I , Varju J , Jeřáb M , Komm M , Imrisek M
Published: October 2022

We introduce detailed numerical modelling of the fast neutral particles inside the duct of a new neutral beam injector (NBI) recently installed at the COMPASS tokamak (major radius

R
0

=
0.56

m

, vessel midplane minor radius

a
=
0.23

m

, toroidal field

B

t

= 0.9–2.1 

T

). This new NBI system is able to deliver

1

M
W

power to the plasma at nominal injection energy of

80

k
e
V

. Collisions with the background neutrals inside the beam duct give birth to fast ions according to the density of the gas and tabulated cross-sections. The ion trajectories are then computed in the complete 3D magnetic field, showing the importance of the stray magnetic field and the magnitude of the field within the gap in between toroidal coils.During the experimental campaign dedicated to the new 1 MW NBI, the beam duct heating was measured by a row of thermocouples located on the top-half of the beam duct. The fast ions collisions with the duct wall cause a local temperature increase with a characteristic pattern. In COMPASS, the location of the fast ions power deposition measured experimentally is in qualitative agreement with modelling of ion losses when following them after the re-ionization process. We trace back the details of the orbits corresponding to deposition at the hot-spot inside the beam duct. Quantitative comparison between the experiment and the simulation shows that a larger than expected amount of neutral gas was inside the duct and this study will guide the design of the future NBI duct in COMPASS Upgrade.
Intersection of 4H-SiC Schottky diodes I–V curves due to temperature dependent series resistance
Authors: Osvald J
Published: October 2022

We theoretically and experimentally analyzed the non-obvious intersections of Schottky diode I–V curves measured at different temperatures caused by increasing the series resistance of the diode with increasing temperature. We considered a homogeneous diode and an inhomogeneous diode with two ways of influencing the I–V curve by the series resistance. In each case we developed a numerical method that enabled anticipation of the I–V intersection point. We studied the Ni/Au/4H-SiC diode for which such an intersection was measured. For homogeneous diodes and temperature interval 300–400 K we found a voltage dispersion of intersection points of only ∼0.002 V, which is in accordance with experimental observations and suppositions in the literature that the curves intersect at almost the same I–V point. Even for an inhomogeneous diode with a common series resistance we obtained a dispersion of the intersection voltage of only ∼0.02 V which is hardly discernible by the common visualization of the I–V curves. The largest dispersion of intersection points was obtained for an inhomogeneous diode composed of non-interacting diode patches.
Semiconductor laser design with an asymmetric large optical cavity waveguide and a bulk active layer near p-cladding for efficient high-power red light emission
Authors: Avrutin Eugene A , Ryvkin Boris S
Published: October 2022

A semiconductor laser design for efficient, high power, high brightness red light emission is proposed, using a large optical cavity asymmetric waveguide and a bulk active layer (AL) positioned very close to the p-cladding. The low threshold carrier density associated with the broad AL, as well as the proximity of the AL to the p-cladding, ensure that the electron leakage current, the major detrimental factor in red lasers, stays modest in a broad range of excitation levels. This in turn promises high-power, efficient operation.
Influence of environmental conditions and voltage application on the electromechanical performance of Nafion-Pt IPMC actuators
Authors: Arnold Allison M , Su Ji , Sabolsky Edward M
Published: October 2022

Ionic polymer–metal composites (IPMCs) are a class of ionic-type electroactive polymers which can be configured as capacitor actuators with very low voltage requirements (⩽5 V AC or DC). Their compact, portable, and lightweight properties, coupled with a biomimetic bending actuation response, makes them ideal for human–machine integrated technologies such as medical implants, active skins, and artificial muscles. Unfortunately, IPMC actuator’s hydration-related sensitivity inhibits practical application in industry and makes experimental research difficult. Therefore, this research sought to quantify the hydration-related parameters of IPMC actuators by applying a wide range of experimental tests to characterize the material’s hydration-dependent features. This included saturation, dielectric, and bending actuation measurements. The IPMC’s degree of saturation properties were classified to establish sample rehydration, preparation, and preservation techniques. IPMC electrical-solvent properties were measured to estimate IPMC actuation performance based on capacitance and dissipation measurements. Maximized actuation was identified for samples tested in 95% RH (i.e. percentage relative humidity). This condition produced an optimized displacement range and retained quality. Through statistical analysis, the work showed large electroactive performance variability (up to 50% deviation), which is a primary obstacle inhibiting this technology from practical application. Finally, an array of electrical field bias applications (i.e. cycled, constant, and post voltage removal monitoring) at intensities ranging from 0.75 to 1.2 V (direct current voltage) were used to quantify actuation rate, maximum displacement, as well as voltage application and removal back-relaxation behavior.
Effects of substrate temperature on the growth of CuO nano/micro rods by ion beam sputter deposition
Authors: Ejigu Assamen Ayalew
Published: October 2022

CuO nano/micro rods were deposited on Si substrates by ion beam sputter deposition at substrate temperatures 300 °C, 350 °C, 400 °C and 450 °C. The effects of changing substrate temperature on the structural properties and surface morphology of the deposited CuO nano/micro rods were studied. Field Emission Scanning Electron Microscopy micrographs showed that at substrate temperature of 300 °C and 350 °C, tiny nanoparticles were observed on the surface of CuO thin films and at substrate temperature of 400 °C and 450 °C, CuO nano/micro rods of lengths (100 nm to 1 μm) and diameters (25 nm to 30 nm) observed in a periodic arrangement. X-Ray Diffraction (XRD) analysis showed that all the diffraction peaks of the samples were single-crystalline CuO corresponded to (

1

¯

11

) orientation. From the crystallographic analysis using XRD data, crystallite sizes of the samples increased (18 to 32 nm) with the increase of substrate temperature. The Micro-Raman spectroscopy investigation shows that all the Raman peaks observed were phonon modes of CuO and as the substrate temperature increased, the intensities of the Rama peaks increased. Hence, by changing substrate temperatures, it is possible to deposit high quality CuO nano/micro thin films with tunable structures, morphologies and sizes for different optoelectronic applications through ion beam sputter deposition.
Synthesis and characterization of GaN/quartz nanostructure using pulsed laser ablation in liquid
Authors: Fakhri Makram A , Alwahib Ali A , Salim Evan T , Abdul Amir Husam Aldin A , Alsultany Forat H , Hashim U
Published: October 2022

The pulsed laser ablation in liquid approach was used to synthesize gallium nitride (GaN) nanoparticles (NPs) at six distinct ablation energies. GaN target with purity of 99.999% submerged in 5 ml ethanol of 99.99% purty and fired with a Nd:YAG pulsed laser. The nanoparticle was deposited on a quartz substrate using the drop cast technique. Two peaks of h-GaN nanostructures are detected in the XRD pattern, at 2θ = 34.64 and 37.98, reflected from the (002) and (100) planes, respectively. The hexagonal crystal nature of GaN is indicated by the structural features, which is shown in the XRD pattern. The greatest laser power, 2000 mJ, shows a modest emission peaking at 3.34 eV, according to photoluminescence (PL) spectra. At 1400 mJ, the highest emission peak was 3.83 eV. The pulsed laser is used in this study to create nanoparticles with various characteristics.
Wave mixing efficiency in InAs/GaAs semiconductor quantum dot optical amplifiers and lasers
Authors: Renaud Thibaut , Huang Heming , Grillot Frédéric , Bimberg Dieter
Published: October 2022

The nonlinear features of both semiconductor optical amplifiers (SOAs) and semiconductor lasers, which are made from the same InAs/GaAs quantum dot (QD) wafers, are investigated in detail. By employing pump-probe driven four-wave mixing as an experimental tool, the wave conversion process shows notably different profiles for the two types of devices. Due to the contributions of ultrafast, sub-picosecond mechanisms, such as carrier heating and spectral hole burning, the pump-probe frequency can be easily tuned to the THz range. SOAs generally benefit more from sub-picosecond carrier dynamics, hence exhibiting a higher conversion efficiency (CE) in the THz range, compared to their laser diode counterparts. The discrepancy even exceeds 10 dB. In addition, laser experiments yield some differences from the amplifier ones, hence leading to a higher nonlinear CE at small detuning ranges. These results strongly improve our insight into the fundamental nonlinear properties of InAs/GaAs QD material, and contribute to the conception of novel devices for future on-chip applications in all-optical communication networks, such as signal wavelength conversion, mode-locking, and optical frequency comb generation.
Fixed template network and dynamic template network: novel network designs for decoding steady-state visual evoked potentials
Authors: Xiao Xiaolin , Xu Lichao , Yue Jin , Pan Baizhou , Xu Minpeng , Ming Dong
Published: October 2022

Objective. Decomposition methods are efficient to decode steady-state visual evoked potentials (SSVEPs). In recent years, the brain–computer interface community has also been developing deep learning networks for decoding SSVEPs. However, there is no clear evidence that current deep learning models outperform decomposition methods on the SSVEP decoding tasks. Many studies lacked the comparison with state-of-the-art decomposition methods in a fair environment. Approach. This study proposed a novel network design motivated by the works of decomposition methods. Fixed template network (FTN) and dynamic template network (DTN) are two novel networks combining the advantages of fixed templates and subject-specific templates. This study also proposed a data augmentation method for SSVEPs. This study compared the intra-subject classification performance of DTN and FTN with that of state-of-the-art decomposition methods on three public SSVEP datasets. Main results. The results show that both FTN and DTN achieved the suboptimal classification performance compared with state-of-the-art decomposition methods. Significance. Both network designs could enhance the decoding performance of SSVEPs, making them promising networks for improving the practicality of SSVEP-based applications.
Modeling the x-ray enhancement in foams for laser-driven soft x-ray sources
Authors: Zheng Jinhua , Kuang Longyu , Zhang Lu , Li Hang , Wang Feng
Published: October 2022

This paper investigates the mechanism that causes x-ray enhancement in high-Z foams for laser-driven soft x-ray sources. By simulation of one-dimensional radiation-hydrodynamics, it is found that the x-ray enhancement is mainly due to the effect that, in a foam target, shock wave compression significantly reduces the energy loss of hydrodynamic motion (kinetic energy). In a solid target this effect is negligible for its low compressibility. Expressions of kinetic energy reduction (ΔE
k = E
k,solid − E
k,foam) are given to model the improvement of the laser-to-x-ray conversion efficiency. The ΔE
k given by the model agrees with the simulation result with about a 15% error for foam density 0.07 – 0.3 g/cc and for laser intensity 0.4 × 1015–2.0 × 1015 W cm−2. The model indicates that the x-ray enhancement is more efficient with a lower foam density and higher laser intensity, which is also presented by the simulation results.
Fast magnetic reconnection and driven plasma rotation in reversed central magnetic shear configuration
Authors: Yu Q. , Günter S.
Published: October 2022

Numerical calculations have been carried out to study the nonlinear growth of the double tearing mode (DTM) in the reversed central magnetic shear configuration for medium-size tokamak plasma parameters, based on two-fluid equations and large aspect ratio approximation. Three different regimes of the DTM growth are found. (a) annular crash regime, existing for a small distance but a not too large plasma rotation frequency difference between two resonant surfaces. In this regime the plasma pressure between two resonant surfaces is flattened due to the fast magnetic reconnection in tens of microseconds, in agreement with experimental observations. In addition, a large plasma rotation shear is generated around the edge of the pressure flattening region right after the fast magnetic reconnection. (b) Core crash regime, existing for a medium distance and a relatively low rotation frequency difference between two resonant surfaces, in which the plasma pressure is flattened over a large region up to the magnetic axis during the fast magnetic reconnection in tens of microseconds, in agreement with experimental observation too. (c) No crash regime, existing for a sufficiently large distance and/or frequency difference between two resonant surfaces. In this regime the mode grows slowly in the nonlinear phase and saturates at a finite amplitude, causing a local flattening of the plasma pressure at the resonant surface but without fast crashes.
Electron beam polarimeter and energy spectrometer
Authors: Muchnoi N.Yu.
Published: October 2022

The backscattering of laser radiation by a relativistic
electron beam is a widely used method for measuring the spin
polarization of electrons. We consider again the properties of the
scattering process paying special attention to recoil electrons.
Based on this consideration we propose the concept of the Compton
polarimeter in which, in addition to all the polarization
components, it becomes possible to accurately measure the energy and
other parameters of the electron beam. To demonstrate the
capabilities of the method we conduct a Monte Carlo simulations of
the polarimeter developed for the FCC-ee project.
Design and experimental study of a rotational piezoelectric energy harvester
Authors: Farias W.P. , Souto C.R. , Castro A.C.
Published: October 2022

This article presents the characterization of an rotational
generator with ceramic piezoelectric transducers, applied to energy
harvesting. The physical structure developed, presents flexibility
in relation to the number of beams, piezoelectric elements and
coupling of generator modules, and keeps the piezoelectric
transducers without direct contact with extern environment, which
allows the device adaptation for practical applications. The
prototype developed has two generator modules, totaling four beams
with two piezoelectric transducers PZT C-64 each, and it worked for
approximately 670 hours, without waste signs. An experimental
configuration was developed to analyze the behavior of the proposed
generator, with the generator being driven by a motor coupled to its
axis with a rotation speed of 1 Hz to 35 Hz. The signals generated
by the beans were connected to variable resistors, obtaining
different power values in each one of the blades, justified by the
manual manufacturing process. The results showed that the suggested
harvester has high durability and the potential to power wireless
sensors that are integrated into rotating machines.