bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulations of COMPASS vertical displacement events with a self-consistent model for halo currents including neutrals and sheath boundary conditions
Authors: Artola F J , Loarte A , Matveeva E , Havlicek J , Markovic T , Adamek J , Cavalier J , Kripner L , Huijsmans G T A , Lehnen M , Hoelzl M , Panek R ,   the COMPASS team,   the JOREK team
Published: April 2021

Abstract
The understanding of the halo current properties during disruptions is key to design and operate large scale tokamaks in view of the large thermal and electromagnetic loads that they entail. For the first time, we present a fully self-consistent model for halo current simulations including neutral particles and sheath boundary conditions. The model is used to simulate vertical displacement events (VDEs) occurring in the COMPASS tokamak. Recent COMPASS experiments have shown that the parallel halo current density at the plasma-wall interface is limited by the ion saturation current during VDE-induced disruptions. We show that usual magneto-hydrodynamic boundary conditions can lead to the violation of this physical limit and we implement this current density limitation through a boundary condition for the electrostatic potential. Sheath boundary conditions for the density, the heat flux, the parallel velocity and a realistic parameter choice (e.g. Spitzer’s resistivity and Spitzer–Härm parallel thermal conductivity) extend present VDE simulations beyond the state of the art. Experimental measurements of the current density, temperature and heat flux profiles at the COMPASS divertor are compared with the results obtained from axisymmetric simulations. Since the ion saturation current density (

J

sat

) is shown to be essential to determine the halo current profile, parametric scans are performed to study its dependence on different quantities such as the plasma resistivity and the particle and heat diffusion coefficients. In this respect, the plasma resistivity in the halo region broadens significantly the

J

sat

profile, increasing the halo width at a similar total halo current.
Detection of 1H NMR signal in a trapped magnetic field of a compact tubular MgB2 superconductor bulk
Authors: Takahashi Yuhei , Naito Tomoyuki , Nakamura Takashi , Takahashi Masato 
Published: April 2021

Abstract
We measured 1H nuclear magnetic resonance (NMR) spectra from silicon rubber in a magnetic field trapped by a compact tubular MgB2 superconductor bulk magnet (60 mm outer diameter, 40 mm inner diameter, and 60 mm height) which was magnetized by field-cooled magnetization from an applied field,

B

a
p
p

, of 0.4778 T at 20 K. The sharpest 1H NMR spectrum of the resonant frequency,

f

R

, of 20.314 MHz, which corresponded to a field strength of 0.4771 T, was observed at 1 mm below the center of the bore of the MgB2 tube. The homogeneity of the trapped field was within 100 ppm between z

=

−2 and +2 mm along the central z-axis, which was evaluated by the position-dependent

f

R

. No change in the trapped field was observed for about 25 d, which corresponded to a decay rate of less than 0.1 ppb h−1. The obtained results suggest that the MgB2 bulk magnet is a promising candidate for a magnetic pole in an NMR apparatus.
A fractal-fractional order Atangana-Baleanu model for Hepatitis B virus with asymptomatic class
Authors: Zhong Jian-Feng , Gul Nadia , Bilal Rubi , Xia Wei-Feng , Altaf Khan Muhammad , Muhammad Taseer , Islam Saeed 
Published: April 2021

Abstract
Hepatitis B is still a major issue in most countries of the world. Due to many death and infection cases, the disease becoming a life-threatening issue and needs proper attention for its eradication. The main aim of this study is to design a new mathematical model with an asymptomatic class based on clinical investigations to study its dynamics. The asymptomatic carriers class do not possess symptoms but infect other healthy people. This new idea has been utilized for the first time in the present analysis with fractal-fractional operators. We formulate the model basically in integer-order and then apply the fractal-fractional derivative in Atangana-Baleanu type. For the fractional model, we study the related results and their numerical solution. Further, we apply the fractal operator together with fractional derivative which is known as fractal-fractional derivative in the Atangana-Baleanu case, and present the model. For the numerical solution, we provide a scheme based on the Adams-Bashforth method and obtained the results graphically. With various choices of the fractal and fractional orders, we present various graphical solutions. The model parameters that can reduce the infection of Hepatitis B are shown graphically. The disease in the population can be minimized well by taking into consideration the model important parameters. The important parameters and their effect have been shown graphically.
Equivalent complex impedance of n-order RLC network
Authors: Chen Hai-Xiang , Wang Ming-Yue , Chen Wan-Jiao , Fang Xin-Yu , Tan Zhi-Zhong 
Published: April 2021

Abstract
Complex n-order complex impedance network is a kind of common complex problems. The electrical characteristics of its equivalent complex impedance are usually complex. We consider a kind of complex impedance network model of two terminal ladder network with complex parameters, and investigate the characteristics of equivalent complex impedance by deriving the analytical formula of equivalent complex impedance. The main research methods are as follows: firstly, the equivalent model is constructed. Secondly, the nonlinear difference equation model is established according to the equivalent model, and then the universal law of the equivalent complex impedance of n-ladder network is given by studying the solution of the nonlinear difference equation. Finally, the specific cases of LC network and non-ideal transmission line are studied respectively, and compared with the relevant results.
Seesaw neutrino dark matter by freeze-out
Authors: Jaramillo Carlos , Lindner Manfred , Rodejohann Werner 
Published: April 2021

Abstract
We investigate whether right-handed neutrinos can play the
role of the dark matter of the Universe and be generated by the
freeze-out production mechanism. In the standard picture, the
requirement of a long lifetime of the right-handed neutrinos implies
a small neutrino Yukawa coupling. As a consequence, they never reach
thermal equilibrium, thus prohibiting production by freeze-out. We
note that this limitation is alleviated if the neutrino Yukawa
coupling is large enough in the early Universe to thermalize the
sterile neutrinos, and then becomes tiny at a certain moment, which
makes them drop out of equilibrium. As a concrete example
realization of this framework, we consider a Froggatt-Nielsen model
supplemented by an additional scalar field which obeys a global
symmetry (not the flavour symmetry). Initially, the vacuum
expectation value of the flavon is such, that the effective neutrino
Yukawa coupling is large and unsuppressed, keeping them in thermal
equilibrium. At some point the new scalar also gets a vacuum
expectation value that breaks the symmetry. This may occur in such a
way that the vev of the flavon is shifted to a new (smaller)
value. In that case, the Yukawa coupling is reduced such that the
sterile neutrinos are rendered stable on cosmological time scales.
We show that this mechanism works for a wide range of sterile
neutrino masses.
A solution to the de Sitter swampland conjecture versus inflation tension via supergravity
Authors: Atli Ugur , Guleryuz Omer 
Published: April 2021

Abstract
The methods of supergravity allow us to derive a multi-field F-term potential. Using this, we denote a generic and non-positive single-field F-term potential. We insert our theory into the scalar-gravity part of the (2,1|1) invariant superconformal action. That action leads us to a de Sitter solution at the inflationary trajectory. One can denote stabilization of fields in terms of the Kähler kinetic terms and single-field slow-roll inflation parameters. We combine these with the de Sitter swampland conjecture to generate a bounded conjecture. This approach allowed us to show that the single field slow-roll inflation works in harmony with bounded de Sitter conjecture for any concave inflation potential.
A novel decoding method for motor imagery tasks with 4D data representation and 3D convolutional neural networks
Authors: Li Ming-ai , Ruan Zi-wei 
Published: April 2021

Abstract

Objective. Motor imagery electroencephalography (MI-EEG) produces one of the most commonly used biosignals in intelligent rehabilitation systems. The newly developed 3D convolutional neural network (3DCNN) is gaining increasing attention for its ability to recognize MI tasks. The key to successful identification of movement intention is dependent on whether the data representation can faithfully reflect the cortical activity induced by MI. However, the present data representation, which is often generated from partial source signals with time-frequency analysis, contains incomplete information. Therefore, it would be beneficial to explore a new type of data representation using raw spatiotemporal dipole information as well as the possible development of a matching 3DCNN. Approach. Based on EEG source imaging and 3DCNN, a novel decoding method for identifying MI tasks is proposed, called ESICNND. MI-EEG is mapped to the cerebral cortex by the standardized low resolution electromagnetic tomography algorithm, and the optimal sampling points of the dipoles are selected as the time of interest to best reveal the difference between any two MI tasks. Then, the initial subject coordinate system is converted to a magnetic resonance imaging coordinate system, followed by dipole interpolation and volume down-sampling; the resulting 3D dipole amplitude matrices are merged at the selected sampling points to obtain 4D dipole feature matrices (4DDFMs). These matrices are augmented by sliding window technology and input into a 3DCNN with a cascading architecture of three modules (3M3DCNN) to perform the extraction and classification of comprehensive features. Main results. Experiments are carried out on two public datasets; the average ten-fold CV classification accuracies reach 88.73% and 96.25%, respectively, and the statistical analysis demonstrates outstanding consistency and stability. Significance. The 4DDFMs reveals the variation of cortical activation in a 3D spatial cube with a temporal dimension and matches the 3M3DCNN well, making full use of the high-resolution spatiotemporal information from all dipoles.
The impact of CT image parameters and skull heterogeneity modeling on the accuracy of transcranial focused ultrasound simulations
Authors: Montanaro Hazael , Pasquinelli Cristina , Lee Hyunjoo J , Kim Hyunggug , Siebner Hartwig R , Kuster Niels , Thielscher Axel , Neufeld Esra 
Published: April 2021

Abstract

Objective. Low-intensity transcranial ultrasound stimulation (TUS) is a promising non-invasive brain stimulation (NIBS) technique. TUS can reach deeper areas and target smaller regions in the brain than other NIBS techniques, but its application in humans is hampered by the lack of a straightforward and reliable procedure to predict the induced ultrasound exposure. Here, we examined how skull modeling affects computer simulations of TUS. Approach. We characterized the ultrasonic beam after transmission through a sheep skull with a hydrophone and performed computed tomography (CT) image-based simulations of the experimental setup. To study the skull model’s impact, we varied: CT acquisition parameters (tube voltage, dose, filter sharpness), image interpolation, segmentation parameters, acoustic property maps (speed-of-sound, density, attenuation), and transducer-position mismatches. We compared the impact of modeling parameter changes on model predictions and on measurement agreement. Spatial-peak intensity and location, total power, and the Gamma metric (a measure for distribution differences) were used as quantitative criteria. Modeling-based sensitivity analysis was also performed for two human head models. Main results. Sheep skull attenuation assignment and transducer positioning had the most important impact on spatial peak intensity (overestimation up to 300%, respectively 30%), followed by filter sharpness and tube voltage (up to 20%), requiring calibration of the mapping functions. Positioning and skull-heterogeneity-structure strongly affected the intensity distribution (gamma tolerances exceeded in

>

80%, respectively

>

150%, of the focus-volume in water), necessitating image-based personalized modeling. Simulation results in human models consistently demonstrate a high sensitivity to the skull-heterogeneity model, attenuation tuning, and transducer shifts, the magnitude of which depends on the underlying skull structure complexity. Significance. Our study reveals the importance of properly modeling the skull-heterogeneity and its structure and of accurately reproducing the transducer position. The results raise red flags when translating modeling approaches among clinical sites without proper standardization and/or recalibration of the imaging and modeling parameters.
Development of an “in situ” calibration methodology to activity meters
Authors: Kuahara L T , Martins E W , Potiens M P A 
Published: April 2021

Abstract
The performance of a safety and efficient practice of a nuclear medicine service depends, among other factors, on a complete quality control program, especially in the case of the radionuclide activity measuring instrument, the activimeter. Several factors may influence the accuracy of the measurements performed with an activimeter, and the largest sources of errors are related to the types of containers that contain radiopharmaceuticals (eg, thickness, size and volume). A complete quality control program should include the calibration of all measurement instruments used in the procedure. However, in Brazil, the actual standard that establishes the requirements of radiological protection for nuclear medicine services (NMS), does not include the calibration of the activimeter. Considering that these instruments, for various reasons, are difficult to remove for sending to a Calibration Service, the purpose of this work is to develop a methodology for activimeter calibration that can be applied “in situ” to the most used radiopharmaceutical, 99mTc.
Estimation of measurement uncertainty in the EDXRF spectrometry of stainless steel
Authors: Krummenauer A , Dias P R , Veit H M 
Published: April 2021

Abstract
The uncertainty in the analysis of nine elements in stainless steels performed with the NITON spectrometer was estimated. Initially, an Ishikawa diagram was used to describe the main sources of uncertainty. After calculating the standard uncertainties of these sources, they were combined to determine the combined standard uncertainty and the expanded uncertainty for each element. An uncertainty contribution graph was developed to assist in analyzing the influences of uncertainty sources on the final value of combined standard uncertainty. A simple uncertainty can be attributed to each element and the calibration curve is a very significant uncertainty source.
Social Profit of Legal Metrology in the Brazilian Electricity Sector
Authors: Rodrigo Otávio Ozanan , Sérgio Ballerini , Araujo Alves Henrique , Costa-Félix  , Rodrigo  
Published: April 2021

Abstract
In Brazil, despite of the undeniable importance of metrology in society, there is still no consensus as to the most effective way to “quantify” this statement. The aims of this study is to present a method to quantify the social impact caused by legal metrological control, focusing on voluntary verification and legal metrology expertise in electrical energy meter . In this sense, this article presents a model, developed exclusively for the public sector, with the objective of quantifying the return or economy in favor of society through National Legal Metrology System direct and indirect actions in the Brazilian electricity sector, considering the 2017 year. This model is an adaptation of Social Profit mode the “Brazilian Agricultural Research Corporation – Embrapa”. . Only laboratories under the control of the Legal Metrology Board, through their delegated bodies, which perform or supervise voluntary checks and metrological examinations performed by the technicians of the Brazilian Network of Legal Metrology and Quality – RBMLQ, were considered. Next step, performance indicators were proposed and validated to obtain social profit. The data show that Inmetro’s actions enable a return to society of US$ 32 million for each US$ 1 million of investment in this activity, pointing to the effectiveness of the model in quantifying the social profit of the agency. In a more detailed analysis it was possible to evaluate a potential revenue recovery for the states, throughTaxes, of the order of US$ 400 million, if the actions of expertise and verification are intensified, pointing to a promising horizon of revenue increase for the Brazilian government through the fight against fraud. Preliminary analyzes show both the massive presence and extreme remoteness of the state are not the best management models to be adopted for the electricity sector. The study suggests, at first, a direct correlation of Inmetro intervention and participation actions in partnership with the private sector in the electricity sector and revenue recovery with reduction in the increase of electric bills. Thus, we infer that the presence of the state as regulator in this case can be effective if adapted to reality. Further studies, however, need to be done. Social profit proved to be effective for use in actions to improve public governance, another point to be explored further on.
Predicted standard deviation of proficiency testing performance in animal nutrition methods
Authors: Souza Gilberto Batista de , Nogueira Ana Rita de Araujo 
Published: April 2021

Abstract
The empirical correlations of the results of over ten years of a proficiency testing of animal nutritional analysis conducted by Embrapa were evaluated. The results demonstrate the similarity of the Horwitz equation proposal, but it is desirable to use individual equations related to the different analyses performed by the laboratories. Using these equations enables a more realistic assessment of possible systematic errors and analytical processes, improving laboratory performance and providing the most reliable results.
An irradiation system for evaluating individual electronic dosimeters in pulsed x-ray beams
Authors: Guimarães Margarete C , Dias Fábio S , Da Silva Teógenes A 
Published: April 2021

Abstract
Electronic dosimeters are widely used for individual monitoring, especially for direct dose equivalent assessment associated with a specific task. Most of x-ray beams used in diagnostic radiology have been considered as pulsed one due to their high intensity during a very short time. This work showed that a Rhos Vari X x-ray machine was feasible to be used to evaluate electronic dosimeters in high pulsed air kerma rates to detect deficiencies in their response. In comparison to continuous x-ray beams, it was observed that personal dose equivalent values were severely underestimated by some electronic dosimeters in pulsed radiation fields.
A study to elaborate a technical manual of veterinary radioprotection
Authors: Sousa CHS , Nascimento ET , Padilha LG , Araújo GS , Peixoto JGP 
Published: April 2021

Abstract
ANVISA Ordinance 453/98 reports the importance of radiological protection, in its fundamental principles, for the protection of patients, workers and the public in the medical and dental radiology sector. However, health surveillance has failed to control veterinary medical radiodiagnosis. Due to the peculiarity of working with animals, the veterinarian has been overexposed to ionizing radiation. This work is quantitative and observational carried out with some clinics, veterinary radiologists and data from personal files, internet and literature. Thirty people were included in the study, where 60% assumed the position of technical manager, 66.7% the radiological protection supervisor, 13% have updated radioprotection training, 66.7% do not carry out quality tests and maintenance of equipment and 76.7% have doubts about radioprotection standards. It was found that a significant proportion of veterinary radiologists are unaware of radioprotection standards, or have doubts about the matter, exposing themselves unnecessarily to ionizing radiation putting their health and that of others at risk
Self-calibration of the secondary laser source in two-color Linnik interferometer
Authors: Malinovski I , França R S , Couceiro I B 
Published: April 2021

Abstract
The imaging Linnik interferometer equipped with two lasers of different colors is under development and metrological study at National Metrology Institute of Brazil (INMETRO). This work reports the self-referenced method for practical calibration of the secondary laser wavelength. The method is based on accurate digitalization and comparison of the waveforms for both reference He-Ne stabilized laser at 633 nm and secondary laser diode at 488 nm. The process makes use of multiple step phase-shifting technique for waveform measurement and multi-parameter fit for wavelength extraction. The advantage of the method is that no extra hardware of realignment of interferometer is required to perform the calibration.
A procedure for assessing geometrical accuracy of selective laser melting processes with standard parts
Authors: Simão I T , Porath M C , Beckert S F 
Published: April 2021

Abstract
The assessment of the geometrical accuracy of an additive manufacturing process is crucial to evaluate its capability to produce parts within specification limits. A standardized procedure for the accuracy evaluation of SLM processes with standard parts is proposed. The procedure includes recommendations for manufacturing, measurement and statistical evaluation. Process repeatability and bias are defined as characteristic accuracy indices. A case study was carried out in which two systems were compared. Repeatability was similar for both systems. Not negligible bias was detected but there was no evidence of significant difference between biases of both systems.
Development of a virtual balance for didactic purposes applied to mass metrology
Authors: Quintão D 
Published: April 2021

Abstract
Inmetro provides technical training in mass metrology area, it seeks to increase the number of hours of hands-on activities. Virtual resources to simulate practices may be used. The objective of this work is to develop a virtual balance that works on a PC and simulates real equipment’s behavior. It has been obtained an indication mathematical model of a real balance through study of physical parameters that influence on weighing and it has been programmed this mathematical model in Virtual Balance Graphical Interface. Mathematical model was validated by comparing Virtual Balance weighing results and experimental results obtained using a real balance.
Industrial Dynamic Measurements of Mechanical Quantities within the Inter-American Metrology System (SIM)
Authors: Savarin Alejandro , Serrano Federico , Pineda Guillermo Silva , Guzman Jorge Torres , Prieto Juan Alberto Arias , Pulido Ivan David Betancur , Chijioke Akobuije , Vlajic Nick , Machado Renato Reis , Oliveira Rafael Soares de 
Published: April 2021

Abstract
Most industrial measurements of force and torque are performed dynamically, while calibrations are performed mostly in static form. It is evident that the dynamic responses of the instruments are very different from the static form. The National Metrology Institutes (NMIs) have been requested by industry to develop solutions for this gap in metrological traceability and have recently undertaken activities to do so. The Inter-American Metrology System (SIM) implemented the project “Industrial Dynamic Measurements (from industry to primary standard)”, involving the NMIs: INTI/Argentina, INMETRO/Brazil, NIST/USA
CENAM/Mexico and INM/Colombia. Main backgrounds, findings and outlooks of the project are highlighted in this paper.