bluuebunny/crossref_metadata_2025 huggingface dataset:
Feasibility study of computational occupational dosimetry: evaluating a proof-of-concept in an endovascular and interventional cardiology setting
Authors: O’Connor U , Walsh C , Gorman D , O’Reilly G , Martin Z , Madhavan P , Murphy R T , Szirt R , Almén A , Andersson M , Camp A , Garcia V , Duch M A , Ginjaume M , Abdelrahman M , Lombardo P , Vanhavere F
Published: September 2022

Individual monitoring of radiation workers is essential to ensure compliance with legal dose limits and to ensure that doses are As Low As Reasonably Achievable. However, large uncertainties still exist in personal dosimetry and there are issues with compliance and incorrect wearing of dosimeters. The objective of the PODIUM (Personal Online Dosimetry Using Computational Methods) project was to improve personal dosimetry by an innovative approach: the development of an online dosimetry application based on computer simulations without the use of physical dosimeters. Occupational doses were calculated based on the use of camera tracking devices, flexible individualised phantoms and data from the radiation source. When combined with fast Monte Carlo simulation codes, the aim was to perform personal dosimetry in real-time. A key component of the PODIUM project was to assess and validate the methodology in interventional radiology workplaces where improvements in dosimetry are needed. This paper describes the feasibility of implementing the PODIUM approach in a clinical setting. Validation was carried out using dosimeters worn by Vascular Surgeons and Interventional Cardiologists during patient procedures at a hospital in Ireland. Our preliminary results from this feasibility study show acceptable differences of the order of 40% between calculated and measured staff doses, in terms of the personal dose equivalent quantity Hp(10), however there is a greater deviation for more complex cases and improvements are needed. The challenges of using the system in busy interventional rooms have informed the future needs and applicability of PODIUM. The availability of an online personal dosimetry application has the potential to overcome problems that arise from the use of current dosimeters. In addition, it should increase awareness of radiation protection among staff. Some limitations remain and a second phase of development would be required to bring the PODIUM method into operation in a hospital setting. However, an early prototype system has been tested in a clinical setting and the results from this two-year proof-of-concept PODIUM project are very promising for future development.
Radiological risk evaluation applied to aerial evacuation procedures in a nuclear scenario
Authors: Alves Daniel F , Stenders Ricardo M , Federico Claudio A , Andrade Edson R
Published: September 2022

This study evaluates the risk assessment of a hypothetical scenario where an off-site radioactive release occurs at a nuclear power plant. By using the code Accident Reporting and Guiding Operational System (Prolog Development Center - PDC/ARGOS) a numerical simulation was performed to simulate exposure conditions in an atmospheric plume of contamination. Crews on a rescue mission traverse the plume through a pre-defined path to evaluate the risk from a hypothetical radiological exposure. Applying a sophisticated epidemiological assessment methodology, radiation doses and risks on the teams were evaluated. Core variables such as gender, age and radiation dose were considered in relation to specific morbidities. It was possible to propose a methodology capable of contributing to the reduction of risks to the personnel involved by connecting the results from the computer simulation and the epidemiological risk assessment.
A review of current inventory for major industries involving naturally occurring radioactive materials in Canada
Authors: Chen Jing
Published: September 2022

Earth materials contain radionuclides of natural origin in varying concentrations. Exposure to natural sources dominates the occupational and public exposure to ionizing radiation. Canada has one of the largest and most diverse supplies of natural resources in the world. A large quantity of material production is associated with a large quantity of waste releases to the environment. Releases from industries involving naturally occurring radioactive material (NORM) can concentrate trace amounts of natural radionuclides and are often poorly characterized. This raises concerns for occupational and public health. Currently, there are data and knowledge gaps in radiological characteristics of NORM products and waste or releases to the environment. For the evaluation of occupational and public exposure to natural sources, a review of current inventory for major industries involving NORM in Canada was conducted with the objective to provide basic information on major issues, help set the priority for research needs to filling these data and knowledge gaps.
Shape reconstruction for deflectometry based on chebyshev polynomials and iteratively reweighted least squares regression
Authors: Guan Jingtian , Li Ji , Yang Xiao , Hu Xiaocai , Chen Xiaobo , Xi Juntong
Published: September 2022

Deflectometry is a technique for measuring the slope data of specular surfaces, and shape reconstruction is the final process based on the measured slopes. Modal methods reconstruct surfaces with expansion polynomials. The coefficients of each polynomial mode are calculated by linear equations composed of the gradient of the polynomials and the measured slope data. Conventional approaches use ordinary least squares to solve the linear equations. However, the equations are overdetermined, and the random outliers will decrease the reconstruction accuracy. The Chebyshev polynomials are suitable for discrete slope data and can be utilized to reconstruct the surface shape in deflectometry. Hence, this paper uses 2D Chebyshev polynomials as the gradient polynomial basis set. An iteratively reweighted least squares algorithm, which iteratively calculates an additional scale factor for each data point, is applied to accomplish robust linear regression. The experiments with both synthetic and measured data prove that the proposed method is robust against noise and has higher reconstruction accuracy for shape reconstruction.
A sleeve and bulk method for fabrication of photonic structures with features on multiple length scales
Authors: Carfagno H S , McCabe L N , Zide J M O , Doty M F
Published: September 2022

Traditional photonic structures such as photonic crystals utilize (a) large arrays of small features with the same size and pitch and (b) a small number of larger features such as diffraction outcouplers. In conventional nanofabrication, separate lithography and etch steps are used for small and large features in order to employ process parameters that lead to optimal pattern transfer and side-wall profiles for each feature-size category, thereby overcoming challenges associated with reactive ion etching lag. This approach cannot be scaled to more complex photonic structures such as those emerging from inverse design protocols. Those structures include features with a large range of sizes such that no distinction between small and large can be made. We develop a sleeve and bulk etch protocol that can be employed to simultaneously pattern features over a wide range of sizes while preserving the desired pattern transfer fidelity and sidewall profiles. This approach reduces the time required to develop a robust process flow, simplifies the fabrication of devices with wider ranges of feature sizes, and enables the fabrication of devices with increasingly complex structure.
Intercalation leads to inverse layer dependence of friction on chemically doped MoS2
Authors: Acikgoz Ogulcan , Guerrero Enrique , Yanilmaz Alper , Dagdeviren Omur E , Çelebi Cem , Strubbe David A , Baykara Mehmet Z
Published: September 2022

We present results of atomic-force-microscopy-based friction measurements on Re-doped molybdenum disulfide (MoS2). In stark contrast to the widespread observation of decreasing friction with increasing number of layers on two-dimensional (2D) materials, friction on Re-doped MoS2 exhibits an anomalous, i.e. inverse, dependence on the number of layers. Raman spectroscopy measurements combined with ab initio calculations reveal signatures of Re intercalation. Calculations suggest an increase in out-of-plane stiffness that inversely correlates with the number of layers as the physical mechanism behind this remarkable observation, revealing a distinctive regime of puckering for 2D materials.
Determination of density of a liquid: revisited through the lens of conditions of floating
Authors: Bhattacharya Ahana , Chattopadhyay K N , Adhikary Chandan
Published: September 2022

A cost-effective method has been developed with utmost efficiency for the determination of density of a liquid. The experimental setup for this purpose is a Polyvinyl chloride (PVC) cylinder fitted with an overflow spout, a volume measuring cylinder, a wooden block along with a hook and a known mass taken from scientific weight box. For this purpose, a PVC cylinder is filled up to the neck of the over flow spout with the liquid whose density is to be measured. A wooden block along with the hook is entered gently inside the cylinder, so that the wooden block along with the hook floats inside the liquid. As a result, some liquid will overflow through the overflow tube, and is collected in the volume measuring cylinder. The volume of the measuring cylinder is noted. Now the wooden block along with the hook is taken out from the liquid and a known mass from the weight box is fixed with the hook. The PVC cylinder again filled up with the liquid up to the neck of the overflow tube and put gently the wooden block fixed with the known mass by the hook inside the liquid. The fixed mass is such that the mass with the block floats inside the liquid, as a result some liquid will overflow again through the overflow tube and is collected in the volume measuring cylinder. The volume is recorded. This volume will be greater than the earlier one. From differences of volume and the mass associated with the block the density of the liquid used can easily be determined.
Hands-on activity using the amplitude and frequency of electromagnetic waves to demonstrate the principle of information transfer
Authors: Siu Lok Yin , Leung Hoi Tik Alvin
Published: September 2022

Electromagnetic (EM) waves are indispensable in modern telecommunications. Despite their essential role in modern technology, EM waves are considered to be an abstract concept by many students. In this activity, an inexpensive two-coil system was constructed in a teaching laboratory and used to demonstrate information transfer by non-sinusoidal EM waves. Twenty secondary school students were invited to try out a hands-on activity developed based on this system. The participants were divided into teams, with some members in each team encoding and transmitting a message using EM signals followed by other members receiving the signal and decoding the message. The message was encoded using different frequencies and amplitudes of the sinusoidal components in the EM signal. In this outreach activity, a significant number of participants was found to hold the misconception that all EM waves are sinusoidal. After this hands-on activity, the number of participants holding this misconception decreased.
Loop the loop experiments
Authors: Cross Rod
Published: September 2022

A loop-the-loop experiment is described to show how sliding friction affects motion of the ball. Conservation of energy can be used to explain the basic physics, but significant energy loss is observed in practice and expands the usefulness of this apparatus as a teaching tool.
Sliding around a vertical loop
Authors: Cross Rod
Published: September 2022

A loop-the-loop experiment usually involves a ball rolling around a vertical loop. A different version of the experiment is described where a nut was allowed to slide around a vertical loop. In both experiments there is a large decrease in kinetic energy when the ball or the nut first enters the loop.
Theory of mean E

×

B shear in a stochastic magnetic field: ambipolarity breaking and radial current
Authors: Guo Weixin , Jiang Min , Diamond Patrick H , Chen Chang-Chun , Cao Mingyun , Li Hanhui , Long Ting
Published: September 2022

The mean E

×

B shear in a stochastic magnetic field is calculated, using the radial force balance relation and transport equations. This analysis is relevant to the L → H transition with resonant magnetic perturbations, and special focus is placed upon the physics of non-ambipolar transport and radial current. The key physical process is the flow of fluctuating currents along wandering magnetic fields. The increments in poloidal and toroidal rotation, density and ion pressure are calculated. The radial envelope of the magnetic perturbations inside the plasma defines a new scale

ℓ

env

, which is the characteristic scale of the magnetic fluctuation intensity profile. The net particle outflow due to stochastic magnetic fields is calculated and is determined by the net radial current through the separatrix. Implications for the L → H transition are discussed.
Effects of microwave plasma treatment on β-Ga2O3 Schottky barrier diodes
Authors: Fang Paiwen , Rao Chang , Liao Chao , Chen Shujian , Wu Zhisheng , Lu Xing , Chen Zimin , Wang Gang , Liang Jun , Pei Yanli
Published: September 2022

In this work, the effects of O2 or N2 microwave plasma treatment on β-Ga2O3 surface prior to Schottky metal deposition are reported. The device uniformity of Schottky barrier diodes is improved significantly by the microwave plasma treatments without any degradation such as ideality factor (near 1.0), and on-state resistance (R
on ∼3 mΩ cm2). The standard deviation of Schottky barrier height (SBH, φB) is as small as less than 10 m eV. Kelvin probe force microscope analysis shows that the surface electrostatic potential after O2 microwave plasma treatment is lower than that of the N2 microwave plasma treatment, which is consistent with the change of SBH obtained by capacitance–voltage (C–V) and current–voltage (I–V) measurements. The relatively low SBH with O2 microwave-plasma treatment corresponds to the high reverse leakage current. The oxygen related adsorption at metal/Ga2O3 interface by O2 microwave plasma treatment confirmed by x-ray photoelectron spectroscopy can be attributed to the SBH and surface potential lowing.
Reflection and lattice mismatch loss analysis in Sb2Se3 solar cells
Authors: Vigil-Galán O , González-Castillo J R , Jiménez-Olarte D
Published: September 2022

Antimony chalcogenide thin film solar cells have been considered promising candidates in the field of photovoltaics, because of their suitable physical and chemical properties. However, the reported experimental record efficiency is far from the corresponding theoretical value. Multiple works have been directed to increase the efficiency of these devices; however, to the best of our knowledge, studies related to losses due to the reflection of the incident radiation in conjunction with the effects of the lattice mismatch of the constituent layers of the solar cells in the formation of interfacial states have not been addressed. Considering these aspects, this work presents a study of reflection losses caused by the layers of materials typically used for processing of solar cells based on Sb2Se3 and a description of the influence of lattice mismatch in the formation of interfacial states, evaluating the impact of both aspects on the efficiency.
A drain extended FinFET with enhanced DC/RF performance for high-voltage RF applications
Authors: Oh Kyounghwan , Kim Hyangwoo , Park Kangwook , Lee Hyung-jin , Kong Byoung Don , Baek Chang-Ki
Published: September 2022

A drain-extended fin field-effect transistor (FinFET) with a dual material gate (DMG) and a high-k field plate (FP), named DF-DeFF, is proposed for high-voltage radio frequency (RF) applications. The FP induces the charge variation in the drain extension, which appears as either the extended depletion in the gate-off state or the electron accumulation in the gate-on state. Along with the FP, the DMG forms a step-like potential variation along the channel, which leads to electron acceleration and the screening effect on the drain-to-source voltage (V
DS). These effects give significant advantages to the DC characteristics, including breakdown voltage (V
BD) and on-resistance (R
on), and the RF characteristics, including transconductance (g
m) and output-resistance (r
o). Compared to the latest high-voltage RF FinFETs, the DF-DeFF shows a drastic improvement in the major performance indicators such as V
BD, cut-off frequency (f
T), and maximum oscillation frequency (f
MAX). These results indicate that DF-DeFF is a FinFET with sufficient competitiveness even in high voltage circumstances.
World’s first application of a self-deployable mechanism based on shape memory polymer composites in Mars explorations: ground-based validation and on-Mars qualification
Authors: Zhang Dou , Liu Liwu , Xu Pengfei , Zhao Yinzhong , Li Qifeng , Lan Xin , Zhang Fenghua , Wang Linlin , Wan Xue , Zou Xin , Zeng Chengjun , Xin Xiaozhou , Dai Wenxu , Li Ying , He Yanchun , Liu Yanju , Leng Jinsong
Published: September 2022

Mars is believed to contain signs of the ancient life and to be the future of humankind. Deep space explorations on Mars have received extensive attention from the scientific and engineering communities. An ancient papyrus scroll-inspired mechanism to deploy the national flag after landing is proposed in this paper. Firstly, a papyrus scroll-inspired structure folded and deployed by shape memory polymer composites (SMPCs) was designed. The material was characterised by both thermodynamic analysis and static mechanical tests. Then, computational modal analysis was completed with material parameters at 25 °C, 55 °C and 85 °C to investigate the temperature effect. Besides, ground-based engineering validations were conducted, including vibration, shock and acceleration tests, as well as deployment verification. Natural frequencies obtained from vibration agreed well with that calculated from simulation. Regular and vacuum deployments showed differences but were both acceptable. Additionally, release reliability greater than 99.99% was obtained through repeated experimental data. Finally, on-Mars qualification was completed with China’s Tianwen-1 mission, with images of the deployed five-star red flag transmitted by the Zhurong rover. It is the world’s first validation of self-deployable mechanism based on SMPCs in deep space, and further applications can be expected.
Design and experimental evaluation of an inchworm motor driven by bender-type piezoelectric actuators
Authors: Han Shuo , Li Zhi , Xu Yunlang , Yang Xiaofeng
Published: September 2022

Piezoelectric actuators (PEAs) are widely used in ultra-precision detection platforms where nano-precision and non-magnetic features are required. With the development of the semiconductor industry, actuators develop toward the tendency of smaller size, higher precision, and longer travel. However, these demands are difficult to meet merely by virtue of a single piezoelectric actuator or a simple structured inchworm piezo motor, which makes it necessary to develop a new drive mode following a different drive principle. In this paper, a novel inchworm piezo motor with bender-type PEAs in phalanx distribution was proposed, which facilitates in reducing the dimension of the motor and enhances the performance and stability of the piezo motor. For the purpose of accommodating the bender-type PEAs and providing the preloads to the bender-type PEAs, a flexible mechanism housing was designed and the modal analysis was finished, avoid resonance and reduce structural vibration. Experimental results show that the resolution of the developed motor is 2 nm or less under the laser interference with an adoption rate of 10 MHz and a resolution of 0.1 nm, while the maximum stroke is over 19 mm at the constant speed of 2.3 mm s−1, and the maximum output force is 41.6 N.
Coupling electromagnetic numerical models of HTS coils to electrical circuits: multi-scale and homogeneous methodologies using the T-A formulation
Authors: Zhou Pengbo , Dos Santos Gabriel , Ghabeli Asef , Grilli Francesco , Ma Guangtong
Published: September 2022

Numerical simulation is an effective tool for predicting the electromagnetic behavior of superconductors. Recently, a finite element method-based model coupling the T-A formulation with an electrical circuit has been proposed: the model presents the superconducting constituent as a global voltage parameter in the electrical circuit. This allows assessing the overall behavior of complex high-temperature superconductor (HTS) systems involving multiple power items, while keeping a high degree of precision on the presentation of local effects. In this work, the applicability of this model has been extended to large-scale HTS applications with hundreds or thousands of tapes by referring to two widely recognized methodologies, multi-scale and homogenization, to improve the computation efficiency. Based on the two approaches, three different models were developed and their effectiveness was assessed using the case study of a 1000 turn cylindrical HTS coil charged by a DC voltage source. The comparison of the calculated global circuit parameters, local field distributions, losses, and computation time proves that the computation efficiency can be improved with respect to a model simulating all HTS tapes, without compromising accuracy. The results indicate that the developed models can therefore be efficient tools to design and optimize large-scale HTS devices used in electrical machines and power grids. It is also found that the inductance of an HTS coil is varied according to the transport current and can be even higher than that of a normal conductor coil with the same geometry. We attribute this result to the superconductor’s non-uniform current distribution and relaxation effect during the dynamic process.
Inverse-coefficient black-box quantum state preparation
Authors: Wang Shengbin , Wang Zhimin , He Runhong , Shi Shangshang , Cui Guolong , Shang Ruimin , Li Jiayun , Li Yanan , Li Wendong , Wei Zhiqiang , Gu Yongjian
Published: September 2022

Black-box quantum state preparation is a fundamental building block for many higher-level quantum algorithms. The basic task of black-box state preparation is to transduce the data encoded as computational basis of quantum state into the amplitude. In the present work, we address the problem of transducing the reciprocal of the data, not the data itself into the amplitude, which is called the inverse-coefficient problem. This algorithm can be used directly as a subroutine in the matrix inversion algorithms. Furthermore, we extend this approach to address the more general nonlinear-coefficient problem in black-box state preparation. Our algorithm is based on the technique of inequality test. It can greatly relieve the need to do quantum arithmetic and the error is only resulted from the truncated error of binary string. The present algorithms enrich the algorithm library of black-box quantum state preparation and will be useful ingredients of quantum algorithm to implement non-linear quantum state transformations.
Topological and quantum stability of low-dimensional crystalline lattices with multiple nonequivalent sublattices*
Authors: Avramov Pavel V , Kuklin Artem V
Published: September 2022

The terms of topological and quantum stabilities of low-dimensional crystalline carbon lattices with multiple non-equivalent sublattices are coined using theoretical analysis, multilevel simulations, and available experimental structural data. It is demonstrated that complex low-dimensional lattices are prone to periodicity breakdown caused by structural deformations generated by linear periodic boundary conditions (PBC). To impose PBC mandatory limitations for complex low-dimensional lattices, the topology conservation theorem (TCT) is introduced, formulated and proved. It is shown that the lack of perfect filling of planar 2D crystalline space by structural units may cause the formation of (i) structure waves of either variable or constant wavelength; (ii) nanotubes or rolls; (iii) saddle structures; (iv) aperiodic ensembles of irregular asymmetric atomic clusters. In some cases the lattice can be stabilized by aromatic resonance, correlation effects, or van-der-Waals interactions. The effect of quantum instability and periodicity breakdown of infinite structural waves is studied using quasiparticle approach. It is found that both perfect finite-sized, or stabilized structural waves can exist and can be synthesized. It is shown that for low-dimensional lattices prone to breakdown of translation invariance (TI), complete active space of normal coordinates cannot be reduced to a subspace of TI normal coordinates. As a result, constrained TI subspace structural minimization may artificially return a regular point at the potential energy surface as either a global/local minimum/maximum. It is proved that for such lattices, phonon dispersion cannot be used as solid and final proof of either stability or metastability. It is shown that ab initio molecular dynamics (MD) PBC Nosé–Hoover thermostat algorithm constrains the linear dimensions of the periodic slabs in MD box preventing their thermostated equilibration. Based on rigorous TCT analysis, a flowchart algorithm for structural analysis of low-dimensional crystals is proposed and proved to be a powerful tool for theoretical design of advanced complex nanomaterials.
Integration of maXs-type microcalorimeter detectors for high-resolution x-ray spectroscopy into the experimental environment at the CRYRING@ESR electron cooler
Authors: Pfäfflein Ph , Allgeier S , Bernitt S , Fleischmann A , Friedrich M , Hahn Ch , Hengstler D , Herdrich M O , Kalinin A , Kröger F M , Kuntz P , Lestinsky M , Löher B , Menz E B , Over T , Spillmann U , Weber G , Zhu B , Enss Ch , Stöhlker Th
Published: September 2022

We report on the first integration of novel magnetic microcalorimeter detectors (MMCs), developed within SPARC (Stored Particles Atomic Physics Research Collaboration), into the experimental environment of storage rings at GSI
6

6

GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64 291 Darmstadt.

, Darmstadt, namely at the electron cooler of CRYRING@ESR. Two of these detector systems were positioned at the 0° and 180° view ports of the cooler section to obtain high-resolution x-ray spectra originating from a stored beam of hydrogen-like uranium interacting with the cooler electrons. While previous test measurements with microcalorimeters at the accelerator facility of GSI were conducted in the mode of well-established stand-alone operation, for the present experiment we implemented several notable modifications to exploit the full potential of this type of detector for precision x-ray spectroscopy of stored heavy ions. Among these are a new readout system compatible with the multi branch system data acquisition platform of GSI, the synchronization of a quasi-continuous energy calibration with the operation cycle of the accelerator facility, as well as the first exploitation of the maXs detectors’ time resolution to apply coincidence conditions for the detection of photons and charge-changed ions.
Two-loop power spectrum with full time- and scale-dependence and EFT corrections: impact of massive neutrinos and going beyond EdS
Authors: Garny Mathias , Taule Petter
Published: September 2022

We compute the density and velocity power spectra at next-to-next-to-leading order taking
into account the effect of time- and scale-dependent growth of massive neutrino perturbations as
well as the departure from Einstein-de-Sitter (EdS) dynamics at late times non-linearly. We
determine the impact of these effects by comparing to the commonly adopted approximate treatment
where they are not included. For the bare cold dark matter (CDM)+baryon spectrum, we find percent
deviations for k ≳ 0.17h Mpc-1, mainly due to the departure from EdS. For the
velocity and cross power spectrum the main difference arises due to time- and scale-dependence in
presence of massive neutrinos yielding percent deviation above k ≃ 0.08, 0.13,
0.16h Mpc-1 for ∑mν
= 0.4, 0.2, 0.1 eV, respectively. We use an
effective field theory (EFT) framework at two-loop valid for wavenumbers k ≫ k
FS,
where k
FS is the neutrino free-streaming scale. Comparing to Quijote N-body
simulations, we find that for the CDM+baryon density power spectrum the effect of neutrino
perturbations and exact time-dependent dynamics at late times can be accounted for by a shift in
the one-loop EFT counterterm, Δγ̅1 ≃ - 0.2 Mpc2/h
2. We find
percent agreement between the perturbative and N-body results up to k ≲
0.12h Mpc-1 and k ≲ 0.16h Mpc-1 at one- and two-loop order,
respectively, for all considered neutrino masses ∑mν
≤ 0.4 eV.
On the cosmological stability of the Higgs instability
Authors: De Luca Valerio , Kehagias Alex , Riotto Antonio
Published: September 2022

The Standard Model Higgs potential becomes unstable at large Higgs field values where its
quartic coupling becomes negative. While the tunneling lifetime of our current electroweak vacuum
is comfortably longer than the age of the universe, quantum fluctuations during inflation might
push the Higgs over the barrier, forming patches which might be lethal for our universe. We study
the cosmological evolution of such regions and find that, at least in the thin wall approximation,
they may be harmless as they collapse due to the backreaction of the Higgs itself. The presence
of the Standard Model Higgs instability can provide a novel mechanism to end inflation and to
reheat the universe through the evaporation of the black holes left over by the collapse of the
Higgs bubbles. The bound on the Hubble rate during inflation may be therefore relaxed.
Charged quark stars in metric f(R) gravity
Authors: Pretel Juan M.Z. , Arbañil José D.V. , Duarte Sergio B. , Jorás Sergio E. , Reis Ribamar R.R.
Published: September 2022

We provide the modified TOV equations for the hydrostatic equilibrium of charged compact stars within the metric f(R) gravitational background. We adopt the MIT bag model EoS for the dense matter and assume a charge distribution where the electric charge density ρ
ch is proportional to the standard energy density ρ. Using the Starobinsky model, we explore the role of the αR
2 term, where α is a free constant and R the Ricci scalar, on the global properties of charged stars such as radius, mass and total charge. We present the dependence of the structure of the star for several values of α and for different values of the constant parameter β ≡ ρ
ch/ρ. Remarkably, we find that the radius decreases with respect to its GR value for low central densities, while the opposite occurs in the high-central-density region. The mass measured at the surface always decreases and the maximum-total charge undergoes a substantial increase as the parameter α increases. We also illustrate the variations of the asymptotic mass as a consequence of the electric charge and the extra quadratic term.
Risk Assessment of Environmental Conditions Affecting the Useful Lifetime of Cherenkov Telescopes at El Roque de Los Muchachos Observatory
Authors: Márquez Patricia , Martínez Oibar , Gaug Markus , Miguel Miranda Jose
Published: September 2022

Construction and operation of ground astrophysical facilities can be affected by adverse weather conditions. Some weather risks are obvious, but still there are times when an unforeseen event distorts the perception of how relevant a climate-related risk is. On the other hand, adverse weather conditions can delay or entirely halt the construction project of an astronomical facility. The impact of weather risks becomes stronger if the facility is built at a site far from urban areas, where maintenance activities and hardware availability become more challenging. This paper aims at proposing a procedure to analyze the impact of environmental risks for an astronomical facility. This procedure is illustrated with a case study: El Roque de Los Muchachos Observatory (ORM). ORM hosts a number of large scale instruments for astrophysics research, which will significantly increase during this decade. We analyze in this paper the environmental conditions affecting the useful lifetime of Cherenkov Telescopes installed at the ORM. After a detailed analysis, we conclude that the risks of strongest magnitude are connected to wild fires. This conclusion diverges from the current risk perception, which is strongly influenced by the recent Cumbre Vieja Eruption event.
A New Polar Ring Galaxy Discovered in the COSMOS Field
Authors: Nishimura Minoru , Matsubayashi Kazuya , Murayama Takashi , Taniguchi Yoshiaki
Published: September 2022

In order to understand the formation and evolution of galaxies fully, it is important to study their three-dimensional gravitational potential for a large sample of galaxies. Since polar-ring galaxies (PRGs) provide useful laboratories for this investigation, we have started our detailed study of a sample of known PRGs by using the data set obtained by the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP). During the course of this study, we have discovered a new PRG, identified as SDSS J095351.58+012036.1. Its photometric redshift is estimated as z ∼ 0.2. The polar ring structure in this PRG appears to be almost perpendicular to the disk of its host galaxy without any disturbed features. Therefore, this PRG will provide us with useful information on the formation of such an undisturbed polar structure. We discuss its photometric properties in detail.
Lightweight broadband microwave absorbing metamaterial with CB-ABS composites fabricated by 3D printing
Authors: Chen Meng-Zhou , Wang Liu-Ying , Liu Gu , Ge Chao-Qun , Li Di-Chen , Liang Qing-Xuan
Published: September 2022

The self-similarity, high geometric symmetry and spatial utilization properties of fractal structures provide new methods for the development of absorbing metamaterials. In this paper, the microwave absorption properties of the gradient dendritic fractal metamaterial structure (GDFMs) based on carbon black and acrylonitrile–butadiene–styrene composites were investigated. The optimal metamaterial structure has an effective absorption in the frequency range of 4.5–40 GHz. The rotational-symmetry GDFMs leads to the polarization independence, and the GDFMs exhibits a wide-angle absorption performance for both TE and TM waves. It is expected that the proposed GDFMs has good application prospects in electromagnetic wave absorption.
Diffraction deep neural network based orbital angular momentum mode recognition scheme in oceanic turbulence
Authors: Zhan Hai-Chao , Chen Bing , Peng Yi-Xiang , Wang Le , Wang Wen-Nai , Zhao Sheng-Mei
Published: September 2022

Orbital angular momentum (OAM) has the characteristics of mutual orthogonality between modes, and has been applied to underwater wireless optical communication (UWOC) systems to increase the channel capacity. In this work, we propose a diffractive deep neural network (DDNN) based OAM mode recognition scheme, where the DDNN is trained to capture the features of the intensity distribution of the OAM modes and output the corresponding azimuthal indices and radial indices. The results show that the proposed scheme can recognize the azimuthal indices and radial indices of the OAM modes accurately and quickly. In addition, the proposed scheme can resist weak oceanic turbulence (OT), and exhibit excellent ability to recognize OAM modes in a strong OT environment. The DDNN-based OAM mode recognition scheme has potential applications in UWOC systems.
Precision measurement and suppression of low-frequency noise in a current source with double-resonance alignment magnetometers
Authors: Zheng Jintao , Zhang Yang , Yu Zaiyang , Xiong Zhiqiang , Luo Hui , Wang Zhiguo
Published: September 2022

Low-noise high-stability current sources have essential applications such as neutron electric dipole moment measurement and high-stability magnetometers. Previous studies mainly focused on frequency noise above 0.1 Hz while less on the low-frequency noise/drift. We use double resonance alignment magnetometers (DRAMs) to measure and suppress the low-frequency noise of a homemade current source (CS) board. The CS board noise level is suppressed by about 10 times in the range of 0.001–0.1 Hz and is reduced to

100

nA/

Hz

at 0.001 Hz. The relative stability of CS board can reach 2.2 × 10–8. In addition, the DRAM shows a better resolution and accuracy than a commercial 7.5-digit multimeter when measuring our homemade CS board. Further, by combining the DRAM with a double resonance orientation magnetometer, we may realize a low-noise CS in the 0.001–1000 Hz range.
A new attention-based 3D densely connected cross-stage-partial network for motor imagery classification in BCI
Authors: Wen Yintang , He Wenjing , Zhang Yuyan
Published: September 2022

Objective. The challenge for motor imagery (MI) in brain-computer interface (BCI) systems is finding a reliable classification model that has high classification accuracy and excellent robustness. Currently, one of the main problems leading to degraded classification performance is the inaccuracy caused by nonstationarities and low signal-to-noise ratio in electroencephalogram (EEG) signals. Approach. This study proposes a novel attention-based 3D densely connected cross-stage-partial network (DCSPNet) model to achieve efficient EEG-based MI classification. This is an end-to-end classification model framework based on the convolutional neural network (CNN) architecture. In this framework, to fully utilize the complementary features in each dimension, the optimal features are extracted adaptively from the EEG signals through the spatial-spectral-temporal (SST) attention mechanism. The 3D DCSPNet is introduced to reduce the gradient loss by segmenting the extracted feature maps to strengthen the network learning capability. Additionally, the design of the densely connected structure increases the robustness of the network. Main results. The performance of the proposed method was evaluated using the BCI competition IV 2a and the high gamma dataset, achieving an average accuracy of 84.45% and 97.88%, respectively. Our method outperformed most state-of-the-art classification algorithms, demonstrating its effectiveness and strong generalization ability. Significance. The experimental results show that our method is promising for improving the performance of MI-BCI. As a general framework based on time-series classification, it can be applied to BCI-related fields.
One dimensional directed polymer ‘memory model’
Authors: Dotsenko Victor
Published: September 2022

In this paper, I propose a very simple statistical ‘memory model’ of one-dimensional directed polymers, which is capable of storing and retrieving a given random quenched trajectory. The model is defined in terms of the elastic string Hamiltonian with the local attractive potential between the dynamic and the quenched random strings. The average overlap between them is calculated as a function of the temperature and the strength of the attractive potential.
Functionalization of biomedical materials using fusion peptides for tissue regeneration
Authors: Guo Xiaolei , Ma Yuan , Ruhan A , Pan Shuo , Guo Yajuan , Shi Xinli , Gao Guobiao , Sun Lei , Wang Jiadao
Published: September 2022

Tissue development deformity or tissue defect is a major clinical challenge. Tissue engineering technology provides a promising solution to these problems. Among them, functional biomaterials with regenerative abilities are one of the development trends. Polypeptide is a small molecule that can be used to modify tissue engineering materials. However, the function of a single polypeptide molecule is limited and insufficient to construct comprehensive microenvironment for tissue regeneration. Fusion peptides combining two or more polypeptide molecules with different functions were expected to achieve multiple efficacies in vivo, providing a novel solution for clinical tissue regeneration engineering applications. This paper reviews the construction methods, degradation process, and biological activities of fusion peptides, and presents recent global research progress and prospects concerning fusion peptides. It provides a reference helping to guide the future exploration and development of fusion peptide-based functional biomaterials for tissue engineering.
The SAGEX review on scattering amplitudes Chapter 2: An invitation to color-kinematics duality and the double copy
Authors: Bern Zvi , Carrasco John Joseph , Chiodaroli Marco , Johansson Henrik , Roiban Radu
Published: September 2022

Advances in scattering amplitudes have exposed previously-hidden color-kinematics and double-copy structures in theories ranging from gauge and gravity theories to effective field theories such as chiral perturbation theory and the Born–Infeld model. These novel structures both simplify higher-order calculations and pose tantalizing questions related to a unified framework underlying relativistic quantum theories. This introductory mini-review article invites further exploration of these topics. After a brief introduction to color-kinematics duality and the double copy as they emerge at tree and loop-level in gauge and gravity theories, we present two distinct examples: (1) an introduction to the web of double-copy-constructible theories, and (2) a discussion of the application of the double copy to calculation relevant to gravitational-wave physics.
Effects of Cooling Methods on the Properties of Concrete with Metakaolin after Thermal Exposure
Authors: Ibeabuchi V. T. , Nwoji C. U. , Eneh B. C.
Published: September 2022

Metakaolin (MK) have been used in concrete as supplementary cementitious materials (SCMs) due to their economic and environmental benefits. Consequently, the use of MK in concrete production contributes to the overall reduction of CO2 release in the environment. However, for a sustainable built environment, material resistance to thermal exposure is of concern. Previous research have studied the performance of MK at elevated temperature, but there is little or no literature on the effect of cooling methods on concrete structures with MK subjected to varying temperature. Hence, this research investigates the effects of cooling methods on the properties of concrete incorporating MK after thermal treatment (fire). Raw MK was calcined, ground and analyzed using XRD and XRF. 15%MK were used to replace cement. Concrete properties (crushing resistance, density, compressive strength) for water and air cooling methods were determined and compared to a control pure concrete. The heating temperatures were 200°C, 350 °C, 550 °C and 750 °C respectively. The incorporation of MK improved properties of the hardened concrete. Charts and tables showing the effects of MK on the concrete properties investigated were presented. The minimum strength obtained was 28.09 N/mm2 during water cooling and maximum strength 35.20N/mm2 during air cooling. The most enhancing effect of Mk as a replacement material was observed in all the cooling methods considered. Water cooling method was found to have caused severe strength reduction in the concrete structure. MK concrete performs better than pure concrete under aircooling method after thermal exposure, hence, can be adopted for fire aggressive environment.
Maintenance of Expanded Polystyrene Building Components in Mount Pleasant Housing Estate, Abuja, Nigeria
Authors: Oloke O. C. , Oluwatobi A. O. , Agboola O. , Adagunodo T. , Adewuyi F.
Published: September 2022

This study assessed user’s satisfaction as well as maintenance related issues associated with expanded polystyrene elements in a residential housing estate in the Federal Capital Territory. Residents of Mount Pleasant Housing Estate, Abuja constituted the study population. Questionnaires were administered to 310 adult residents of the housing estate out of which 267 were retrieved, constituting 86.1% rate of response and used for analysis. Data were analysed with basic descriptive tools of frequency, percentage and mean score derived from 5-Point Likert scale. Results were presented in tables and then discussed. The study established amongst others that expanded polystyrene materials are used for different components of housing units with partition walls, decorative finishes and window hoods having 79.4%, 68.2% and 64.4% of usage respectively. The study found amongst others that respondents generally agree that EPS elements are costlier in terms of maintenance and require special skill to fix. It was further observed that respondents are of the opinion that EPS elements do not breakdown easily or frequently. Concluding, the respondents ranked their satisfaction level with the aesthetics and moisture resistance above other qualities of EPS components. The study therefore recommended further research to discover how EPS materials can be used to build complete housing unit. Furthermore, developers and builders should as a matter of policy embrace the use of EPS while special awareness creation programme is organized to enlighten the general public on the benefits of EPS to housing development in Nigeria.
Experimental and numerical study of contact fatigue for 18CrNiMo7-6 and 20MnCr5 carburized gear tooth
Authors: Palma Calabokis Oriana , Núñez de la Rosa Yamid Enrique , de Moraes Samara Paulin , Antunes Estela Vicentim , Cousseau Tiago , da Silva Carlos Henrique
Published: September 2022

Gear manufacturers must make decisions about the manufacturing materials and superficial treatments. The best performance as to a type of failure should be evaluated. However, it is a time-demanding and costly process. The present work proposes a methodology for a comprehensive assessment (experimental and computational) of contact fatigue of gears in FZG test rig. The materials investigated were 18CrNiMo7-6 and 20MnCr5 alloy steels, widely used in industrial and automotive transmission systems, but with very different raw material costs, which can exceed twice the first compared to the second. The study evaluated the contact analysis between gears from the macroscopic point of view and the microscopic (inclusion of roughness). At the same time, the evolution of roughness and pit-damaged area after each test stage was monitored. The approach determined the stress field after each loading cycle and thus correlating the regions of higher stresses with surface and subsurface fatigue (micropitting and pitting). In addition, Weibull’s statistical analysis and SEM-EDS observations were executed. In many cases, the methodology correlated the increased roughness and pitting affected area with the regions submitted to the higher contact stress. Observations by SEM-EDS revealed that the occurrence of plastic deformation as a mechanism of wear should be considered in the equations of microscopic stress analysis. The similar fatigue life of such different materials may be correlated to the competitive mechanisms of higher mechanical strength of 18CrNiMo7-6 and better crack propagation characteristics of 20MnCr5. The methodology proved to be consistent for fatigue failure analysis of gears in FZG test rig.