bluuebunny/crossref_metadata_2025 huggingface dataset:
Topological review of hybrid RES based multi‐port converters
Authors: Yalla Satya Prasanth , Subudhi Partha Sarathi , Ramachandaramurthy Vigna Kumaran
Published: February 2022

Depletion of natural resources like gas, oil, coal along with environment pollution increased the popularity of the Renewable Energy Sources (RES). Power Electronic converters are utilized for conversion of power from RES to coordinate the stand‐alone load and utility grid. MPPT control is also established by these converters to supply the standalone or grid‐connected load despite of the RES's unpredictable nature. In order to reduce the number of switches used for integrating RES to drive loads, Multi‐port converters are developed. These converters have the capability to supply more than one load simultaneously. Furthermore, more number of RESs are connected using these converters in order to drive common loads. Available literatures do not explain in detail regarding various types of multi‐output converters, their advantages, disadvantages, application area and control techniques used in order to drive these converters. In this context, a review of recent advances in multi‐port DC‐DC converters for different application using hybrid RESs is carried out. Initially in literature, few DC‐DC converters are connected in parallel, series configuration and used as multi‐port converters. Multi‐stage conversion is realized using DC‐AC‐DC conversion. Advantages of conventional converters are integrated in order to develop derived multi‐output converters. These multi‐port converters have the capability to drive both DC and AC loads from a single DC input source. The converters share common power electronics equipment while generating both DC and AC power simultaneously. Furthermore, these multi‐port converters also use single step power conversion process which reduces the overall system loss. As these hybrid multi‐port converters use lesser number of power electronic switches, the control complexity of these converters reduces compared to the conventional converters connected in cascaded or parallel manner to drive loads. A detailed review of these multi‐port converters with respect to topologies, and operating principle, diverse reliability and effectiveness are presented in this paper. This survey helps designers to select the appropriate RES‐based multi‐port converters for their respective applications.
Range and Doppler reconstruction for sparse frequency agile linear frequency modulation‐orthogonal frequency division multiplexing radar
Authors: Liu Zhixing , Quan Yinghui , Wu Yaojun , Xu Kaijie , Xing Mengdao
Published: February 2022

Sparse frequency agile linear frequency modulation‐orthogonal frequency division multiplexing (LFM‐OFDM) radar can improve anti‐interference ability as well as reduce the sampling rate of the radar system. However, the frequency agility makes it difficult to realize coherent processing by using the fast Fourier transform. To overcome this problem, a signal processing scheme for the sparse frequency agile LFM‐OFDM radar is proposed to obtain the high range and Doppler resolution in this study. The subcarriers are synthesised to an LFM signal in the time domain at first. Then, within the framework of the compressed sensing theory, an improved orthogonal matching pursuit algorithm is proposed to obtain the high‐resolution range‐velocity profile while reducing the computation complexity. Finally, several numerical simulations are provided to verify the effectiveness of the proposed method for moving targets.
Interacting climate change effects on mussels (Mytilus edulis and M. galloprovincialis) and oysters (Crassostrea gigas and Ostrea edulis): experiments for bivalve individual growth models
Authors: Kamermans Pauline , Saurel Camille
Published: February 2022

The physiological response of two species of mussels (Mytilus edulis and M. galloprovincialis) and two species of oysters (Crassostrea gigas and Ostrea edulis) to temperature, oxygen levels and food concentration, factors likely to vary as a result of climate change, was determined experimentally. Bivalves of similar size from different origins were exposed to six temperatures (3, 8, 15, 20, 25 and 30 °C) at two food regimes (2 and 10 μg Chl a L−1) for 6 weeks. In a parallel running experiment M. edulis from the same batches were exposed to three different temperatures (15, 20 and 25 °C) and three different oxygen levels (30, 50 and 100%) at two food regimes (2 and >8 μg Chl a L−1) for 3–4 weeks. Survival during the experiment ranged from 93% to 100% except for the mussels exposed to 30 °C which showed 100% mortality after three to 32 days. Higher food conditions showed higher optimal temperatures for growth of mussels and oysters. In addition, at the high food treatment, reduced O2 saturation resulted in lower growth of mussels. At the low food treatment there were no differences in growth among the different O2 levels at the same temperature. At high food concentration treatment, M. edulis growth was higher with low temperature and high oxygen level. Condition index was higher at higher food concentrations and decreased with increasing temperature. In addition, condition was lower at low oxygen saturation. Lower clearance rates were observed at high food concentrations. At 100% saturation of oxygen, mussel clearance rate increased with temperature at High food regime, but not at Low food regime. Mussel clearance rates were significantly reduced with low oxygen concentrations together with high temperature. Oxygen consumption significantly increased with temperature. Oxygen saturation was the main factor affecting mussel clearance rate. High temperature and low oxygen concentration combined significantly reduced clearance rate and increased oxygen consumption. These response curves can be used to improve parameterisation of individual shellfish growth models taking into consideration factors in the context of climate change: temperature, food concentration, oxygen concentration and their interactions. The observation that abiotic factors interact in affecting mussels and oysters is an important result to take into account.
From early to present and future achievements of EELS in the TEM
Authors: Colliex Christian
Published: February 2022

This paper reviews the implementation of Electron Energy Loss Spectroscopy (EELS) in a Transmission Electron Microscope (TEM), as an essential tool for advanced analytical studies, exhibiting a unique level of performance in terms of spatial resolution down to the interatomic distances for imaging and sensitivity down to the single atom for elemental identification. In terms of spectral resolution, it offers access with a resolution as good as a few meV, to a very broad spectral domain extending from tens of meV (in the IR) up to a few keV (in the X-ray). This new generation of instrument (EELS+(S)TEM) is now routinely used to investigate the structural, spectral, electronic and chemical properties of a wide range of materials and to broaden spectacularly the field of novel information which it provides. A first part of the paper describes the major progress in advanced instrumentation brought by the novel pieces of equipment (spectrometers, monochromators, aberration correctors and detectors) together with the newly elaborated tools for the acquisition and processing of huge data collections. The second part is devoted to the description of the information contained in a global EELS spectrum: (i) from the core-loss domain implying excitations from inner-shell atomic electrons and its application in elemental, chemical and electronic mapping; (ii) from the low-energy domain exhibiting individual or collective excitations of the valence and conduction electron gas, with its most recent developments in band gap mapping and nanoplasmonics; (iii) in the ultra-low energy domain, which is now in its infancy, the surface collective electron excitations, molecular bonds and the vibrations of phonons at surfaces and in the bulk of nanostructures. The third part is devoted to the exploration of unconventional domains of applications, which in many cases associate the EELS acquisition with the generation and the capture of other signals in various environments, in situ operation (temperature, pressure...), absorption or generation of photons (cathodoluminescence, X-ray emission), acquisition and handling of multidimension data (space, energy, momentum, time). In conclusion, EELS fifty years after its first recognition as a useful actor in the development and promotion of the analytical microscopy, has nowadays become an essential tool for the acquisition of many physical parameters with ultimate resolution, thus opening new routes in nanophysics to be explored.
Direct Measurement of Carbon Fusion at Astrophysical Energies with Gamma-Particle Coincidences
Authors: Heine M. , Fruet G. , Courtin S. , Jenkins D.G. , Adsley P. , Brown A. , Canavan R. , Catford W.N. , Charon E. , Curien D. , Della Negra S. , Duprat J. , Hammache F. , Lesrel J. , Lotay G. , Meyer A. , Monpribat E. , Montanari D. , Morris L. , Moukaddam M. , Nippert J. , Podolyák Zs. , Regan P.H. , Ribaud I. , Richer M. , Rudigier M. , Shearman R. , de Séréville N. , Stodel C.
Published: February 2022

We present 12C+12C direct fusion measurements with STELLA UKFATIMA, that reach into the region of astrophysics interest relevant to massive stars (M⊙ ≈ 25) using self-supporting thin rotating carbon foils [1]. We demonstrate that detecting gammas and light charged particles in coincidence with nanosecond timing is key for effective background reduction achieving reliable measurements in the sub-nanobarn range. We give details about core developments of the detection apparatus as well as the coincidence-analysis procedure of low count statistics. The present data largely follows the phenomenological hindrance interpolation and shows indication for resonant behaviour at the lowest energy explored.
Slow White Dwarf Mergers as a New Galactic Source of Trans-Iron Elements
Authors: Battino Umberto , Lederer-Woods Claudia , Travaglio Claudia , Röpke Friedrich Konrad , Gibson Brad
Published: February 2022

The astrophysical origins of the heaviest stable elements that we observe today in the Solar System are still not fully understood. Recent studies have demonstrated that H-accreting white dwarfs (WDs) in a binary system exploding as type Ia supernovae could be an efficient p-process source beyond iron. However, both observational evidence and stellar models challenge the required frequency of these events. In this work, we calculate the evolution and nucleosynthesis in slowly merging carbon-oxygen WDs. As our models approach the Chandrasekhar mass during the merger phase, the 22Ne(α,n)25Mg neutron source reaction is activated in the external layers of the primary WD, where the carbon-rich material accreted from the secondary WD is burned via the 12C+12C reaction, which provides the necessary α-particles via the 12C(12C,α)20Ne channel. The resulting neutron capture abundance distribution closely resembles a weak s-process one and peaks at Zr, which is overproduced by a factor of 30 compared to solar. The mass of the most external layers enriched in first-peak s-process elements crucially depends on the 12C+12C reaction rate, ranging between 0.05 M⊙ and ~0.1 M⊙. These results indicate that slow white dwarf mergers can efficiently produce the lightest p-process isotopes (such as 74Se, 78Kr, 84Sr, 92Mo and 94Mo) via γ-induced reactions if they explode via a delayed detonation mechanism, or eject the unburned external layers highly enriched in first peak s-process elements in the case of a pure deflagration. In both cases, we propose for the first time that slow WD mergers in binary systems may be a new relevant source for elements heavier than iron.
Screening Effects on Electron-Capture Rates and Type Ia Supernova Nucleosynthesis
Authors: Suzuki Toshio , Mori Kanji , Honma Michio , Famiano Michael A. , Kajino Toshitaka , Kusakabe Motohiko , Balantekin A. Baha
Published: February 2022

Nucleosynthesis of iron-group elements in Type Ia supernovae is studied for single-degenerate models with the use of electron-capture rates updated with the new shell-model Hamiltonian in pf -shell. An over-production problem of neutron-rich iron-group isotopes compared with the solar abundances is now found to be suppressed within a factor of about twice for the updated weak rates. Effects of screening on nucleosynthesis are investigated for explosion models of fast deﬂagration and slow deﬂagration with delayed detonation. The e-capture rates are reduced by the screening, especially by the screening effects on the ions. The production yields of most neutron-rich isotopes such as 50Ti, 54Cr and 58Fe are found to be suppressed most by the screening. The inclusion of the screening is desirable for precise evaluation of abundances of neutron-rich nuclides.
Description of weak-interaction rates within the relativistic energy density functional theory
Authors: Ravlić Ante , Yüksel Esra , Niu Yifei , Paar Nils , Colò Gianluca , Khan Elias
Published: February 2022

A new theoretical framework has been established and applied in the calculation of electron capture (EC) and β-decay rates in stellar environment, characterized by high density and temperature. For the description of the nuclear properties, the finite-temperature Hartree Bardeen-Cooper-Schrie_er (FTHBCS) theory based on the relativistic derivative-coupling D3C* interaction is employed. In order to describe the charge-exchange transitions, the finitetemperature proton-neutron quasi-particle random-phase approximation is developed (FT-PNRQRPA) which includes both temperature and pairing correlations. In the FT-HBCS calculations, only the isovector pairing is included, while in the residual interaction of the FT-PNRQRPA both the isovector and isoscalar pairing contribute. In this work, results for EC and β-decay rates are presented in the temperature interval T = 0–1.5 MeV and stellar density ρYe = 107 and 109 g/cm3. Both allowed 0+, 1+ and first-forbidden transitions 0−, 1− and 2− are included in the calculations. It is shown that interplay between pairing correlations and finite-temperature effects can lead to significant changes in rates. It is also important to include de-excitations, i.e. transitions with negative Q-value, that become increasingly significant at higher temperatures especially for p f -shell nuclei.
Massive first star binaries as new tools for Galactic archaeology
Authors: Suda Takuma , Saitoh Takayuki R. , Moritani Yuki , Matsuno Tadafumi , Shigeyama Toshikazu
Published: February 2022

Binary systems are important probes of the origin of stars with peculiar chemical features through the interactions between two stars. We have studied the evolution of a metal-free massive binary after the collision of the supernova ejecta with a low-mass companion. Theoretical models are developed using simulations of binaries after core-collapse supernovae using stellar evolution models, supernova ejecta models, and hydrodynamic simulations of the system consisting of supernova ejecta and companion stars. We find that these first star survivors will be observed as metal-rich halo stars in our Galaxy. In combination with the theoretical research, we looked for observational counterparts in the Galactic halo using the observational database where elemental abundances and kinematic data are available. We have also searched for the progenitor binary systems based on radial velocity monitoring. We report the current status of the search for massive binaries in the solar vicinity. The proposed scenario demands a new channel of star formation in the early universe and is a supplementary scenario for the origin of the known metal-poor stars.
A Framework for Optimizing Software Regression Test Case based on Modified-Ant Colony Optimization (M-ACO)
Authors: Silvarajoo Abrahmi , Hazim Alkawaz Mohammed
Published: February 2022

Software Regression Testing (SRT) helps with the modified code to ensure that no other new defects have been trained and significantly impact the existing code. SRT is a time and cost taking process. Test Case Prioritization (TCP) helps to reschedule test cases (TC’S) and picks according to the prioritization, which allows the software testers to maximize the number of faults detected within a given time frame. Ant Colony Optimization (ACO) is an optimization algorithm motivated by the searching behavior of insects. This paper proposes a simple framework for the novel Modified-ACO (m-ACO) to prioritize the TC’s. m-ACO is planned as the adjusted type of the ACO method, which reschedules the execution sequence of TC’S by changing the wonder of characteristic insects for choosing their food source. The proposed Framework will help the software testers save their time to execute SRT TC’s. It has been tested for Zasta Billing Web Application and compared the time taken to complete the SRT manually and using the proposed Framework.The proposed Framework helps to reduce the time taken from 90 days to 45 days to achieve the SRT.
Assessing the impact of translation guidelines in Wikipedia
Authors: Góngora-Goloubintseff José Gustavo
Published: February 2022

Wikipedia is a multilingual, user-driven online encyclopaedia available in 325 languages and language varieties. Such linguistic diversity has drawn the attention of translation scholars over the past decade. Previous research has addressed, among other issues, the quality of translated Wikipedia entries, the motivations driving editors-translators, and the taxing negotiations behind editorial changes. Nevertheless, the processes underpinning translation practices in the encyclopaedia have often been overlooked. Consequently, this paper adopts a praxeological approach to translation by analysing documented standards across four Wikipedia language communities and the extent to which 16 experienced translators have assimilated them. The findings suggest that Wikipedia guidelines on translation have slight but tangible differences across the communities under investigation. Moreover, the interview data showed a tendency among participants to attach more importance to cross-wiki editing policies than to any local translation guidelines. This preference ultimately reinforces previous claims that translation and editing in Wikipedia form a continuum.
Kink as a Form of Leisure: Kinky Events and the People who Love Them
Authors: Webster Craig , Ivanov Stanislav
Published: February 2022

In recent years, there has been a popularization of non-mainstream sexual/cultural practices. The sensation of Fifty Shades of Grey has led to the general public becoming increasingly aware of the kink/BDSM lifestyle. The BDSM/kink/sado-masochist lifestyle has largely thrived under the radar of many in the general public and the subculture/lifestyle has organized and held events for decades. In this article, we discuss the various events of the kink/BDSM subculture/lifestyle and illustrate the importance of the non-play events for those in the lifestyle. The authors have fielded two ground-breaking global surveys that delve into the prevailing social institution of the kink/BDSM lifestyle, The Munch, an event in which no BDSM activities take place. The intention of this research is to show the methods that participants and organizers use in order to protect the identity of those attending non-play BDSM events that take place in the general public. The findings show that those participating in munches, a popular form of non-play events, tend to use their real names, although there is a large minority that do not. The analysis intends to give insight into those who operate below the radar of society and still have a vibrant social scene.

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A publication of Vancouver Island University World Leisure Centre of Excellence

© Craig Webster and Stanislav Ivanov 2020
Does performing resistance exercise to failure homogenize the training stimulus by accounting for differences in local muscular endurance?
Authors: Exner Ryan J. , Patel Mana H. , Whitener Dominic V. , Buckner Samuel L. , Jessee Matthew B. , Dankel Scott J.
Published: February 2022

The prescription of resistance exercise often involves administering a set number of repetitions to be completed at a given relative load. While this accounts for individual differences in strength, it neglects to account for differences in local muscle endurance and may result in varied responses across individuals. One way of potentially creating a more homogenous stimulus across individuals involves performing resistance exercise to volitional failure, but this has not been tested and was the purpose of the present study. Individuals completed 2 testing sessions to compare repetitions, ratings of perceived exertion (RPE), muscle swelling and fatigue responses to arbitrary repetition (SET) vs. failure (FAIL) protocols using either 60% or 30% one‐repetition maximum. Statistical analyses assessed differences in the variability between protocols. Forty‐six individuals (25 females and 21 males) completed the study. There was more variability in the number of repetitions completed during FAIL when compared to SET protocols. Performing the 60% 1RM condition to failure appeared to reduce the variability in muscle swelling (average variance: 60%‐SET = .034, 60%‐FAIL = .023) and RPE (average variance: 60%‐SET = 4.0, 60%‐FAIL = 2.5), but did not alter the variability in muscle fatigue. No differences in variability were present between the SET‐30% and FAIL‐30% protocols for any of the dependent variables. Performing resistance exercise to failure may result in a more homogenous stimulus across individuals, particularly when using moderate to high exercise loads. The prescription of resistance exercise should account for individual differences in local muscle endurance to ensure a similarly effective stimulus across individuals.

Highlights

There is a large variance in the number of repetitions individuals can complete even when exercising with the same relative load.

Ratings of perceived exertion and muscle swelling responses become more homogenous when exercising to volitional failure as compared to using performing a set number of repetitions, particularly when moderate to higher loads are used.

The prescription of exercise should take into consideration the individual's local muscle endurance as opposed to choosing an arbitrary number of repetitions to be completed at a given relative load.
Modeling inductive radio frequency coupling in powerful negative hydrogen ion sources: validating a self-consistent fluid model
Authors: Zielke D , Briefi S , Lishev S , Fantz U
Published: February 2022

Radio frequency (RF) negative hydrogen ion sources utilized in fusion and for accelerators use inductively coupled plasmas, which are operated at a low driving frequency, high power densities and gas pressures in the order of 1 MHz, 10 W cm−3 and 1 Pa, respectively. In this work a numerical fluid model is developed for a self-consistent description of the RF power coupling in these discharges. After validating the RF power coupling mechanism, such a model is a valuable tool for the optimization of RF power coupling and hence can help to increase the efficiency and reliability of RF ion sources. The model validation is achieved using measurements from the ITER RF prototype ion source. Steady state numerical solutions are obtained for the first time, where all modeled trends fit well. Remaining systematic quantitative differences could be caused by 3D effects such as highly non-uniform magnetic fields that cannot be captured in the current model formulation, which is 2D cylindrically symmetric. The coupling between the RF fields and the electrons is realized in the electron momentum transport equation, where approximations consistent with the operating regime of RF ion sources are applied. Here large magnetic RF fields lead to a plasma compression by the nonlinear RF Lorentz force. Using a local approximation for the electron viscosity, it is found that increased diffusion of the RF current density mitigates the compression. Navier–Stokes equations for the neutral atoms and molecules are used to capture neutral depletion. In this way it is shown that at high powers neutral depletion has a large impact on the power coupling via the viscosity of the electrons. The application of the self-consistent model for optimization of the RF power coupling will be described in a forthcoming paper.
The prolonged decay of RKKY interactions by interplay of relativistic and non-relativistic electrons in semi-Dirac semimetals
Authors: Duan Hou-Jian , Wu Yong-Jia , Yang Yan-Yan , Zheng Shi-Han , Zhu Chang-Yong , Deng Ming-Xun , Yang Mou , Wang Rui-Qiang
Published: February 2022

The Ruderman–Kittel–Kasuya–Yosida (RKKY) interaction has been extensively explored in isotropic Dirac systems with linear dispersion, which typically follows an exponent decaying rate with the impurity distance R, i.e., J ∝ 1/R

d
(1/R
2d−1) in d-dimensional systems at finite (zero) Fermi energy. This fast decay makes it rather difficult to be detected and limits its application in spintronics. Here, we theoretically investigate the influence of anisotropic dispersion on the RKKY interaction, and find that the introduction of non-relativistic dispersion in semi-Dirac semimetals (S-DSMs) can significantly prolong the decay of the RKKY interaction and can remarkably enhance the Dzyaloshinskii–Moriya interaction around the relativistic direction. The underlying physics is attributed to the highly increased density of states in the linear-momentum direction as a result of the interplay of relativistic and non-relativistic electrons. Furthermore, we propose a general formula to determine the decaying rate of the RKKY interaction, extending the typical formula for isotropic DSMs. Our results suggest that the S-DSM materials are a powerful platform to detect and control the magnetic exchange interaction, superior to extensively adopted isotropic Dirac systems.
What can CMB observations tell us about the neutrino distribution function?
Authors: Alvey James , Escudero Miguel , Sabti Nashwan
Published: February 2022

Cosmic Microwave Background (CMB) observations have been used extensively to constrain key properties of neutrinos, such as their mass. However, these inferences are typically dependent on assumptions about the cosmological model, and in particular upon the distribution function of neutrinos in the early Universe. In this paper, we aim to assess the full extent to which CMB experiments are sensitive to the shape of the neutrino distribution. We demonstrate that Planck and CMB-S4-like experiments have no prospects for detecting particular features in the distribution function. Consequently, we take a general approach and marginalise completely over the form of the neutrino distribution to derive constraints on the relativistic and non-relativistic neutrino energy densities, characterised by N
eff = 3.0 ± 0.4 and ρν,0
NR < 14 eV cm-3 at 95% CL, respectively. The fact that these are the only neutrino properties that CMB data can constrain has important implications for neutrino mass limits from cosmology. Specifically, in contrast to the ΛCDM case where CMB and BAO data tightly constrain the sum of neutrinos masses to be ∑m
ν < 0.12 eV, we explicitly show that neutrino masses as large as ∑ m
ν∼ 3 eV are perfectly consistent with this data. Importantly, for this to be the case, the neutrino number density should be suitably small such that the bound on ρν,0
NR = ∑ m
ν
n
ν,0 is still satisfied. We conclude by giving an outlook on the opportunities that may arise from other complementary experimental probes, such as galaxy surveys, neutrino mass experiments and facilities designed to directly detect the cosmic neutrino background. GitHub: Parameter files for MCMC analysis and code to reproduce all plots can be found here.
Regulation of optical properties by applied external fields for a quantum well with Hulthen potential
Authors: Turkoglu Aslan
Published: February 2022

In this present study, the effects of electric, magnetic, and non-resonant intense laser field (ILF) on the linear, third-order nonlinear, and total optical absorption coefficients (TOACs) and relative refractive index changes (RRICs) of GaAs quantum well, having Hulthen confinement potential, were theoretically investigated. In addition, the dependence of the nonlinear optical properties in the structure on the optical intensity of incident photon and the inverse relaxation time was also calculated. To do this research, firstly the energy eigenvalues and eigenfunctions of the structure were calculated by using the effective mass and envelope function approaches. By using these calculated subband energy levels and wave functions belonging to these levels, the nonlinear optical properties of the system were obtained via the iterative method, within the compact density matrix approach framework. The obtained numerical results show that the optical properties of the considered system depend on the externally applied fields. With the applied external electric and magnetic field, the peak positions of TOACs and RRICs shift to higher energies, and the peak magnitudes increase. The high-frequency ILF applied to the structure shifts the peak positions of TOACs and RRICs initially towards higher energies and then towards lower energies and their peak sizes increase. These results show that the optical properties of the system can be adjusted purposively by changing the magnitude of applied external fields.
Surface oxygen versus native oxide on tungsten: contrasting effects on deuterium retention and release
Authors: Dunand A. , Minissale M. , Faure J.-B. , Gallais L. , Angot T. , Bisson R.
Published: February 2022

We performed a direct comparison of deuterium retention and release from tungsten in presence or in absence of oxygen impurities. A single crystal of W(110) was used to prepare tungsten with four different surface states: with its native oxide, atomically clean, covered with half a monolayer of oxygen atoms, and covered with three fourths of a monolayer of oxygen atoms. For a D ion fluence of 3 × 1021 D+ m−2 implanted at 300 K, deuterium retention was highest with the native oxide, lowest with three fourths of a monolayer of oxygen atoms at the surface and intermediate for the clean surface. This counterintuitive result is explained by a different localization of deuterium retention in these samples. For tungsten with its native oxide, deuterium retention occurs solely in the bulk, i.e. below the first atomic plane of the surface. For clean tungsten, deuterium retention occurs in part at the surface and sputtering should play a role. For tungsten with a sub-monolayer surface coverage of oxygen atoms, a transition from surface to bulk retention is observed above half a monolayer of adsorbed oxygen. Striking differences in desorption peak(s) temperature(s) are observed between D ion-implanted samples and D2 molecules-exposed samples. These results highlight the importance of the (near-) surface localization of oxygen and deuterium on the temperature dependence of deuterium desorption rate i.e. on the fusion fuel recycling coefficient.
A noniterative solution to the inverse Ising problem using a convex upper bound on the partition function
Authors: Sano Takashi
Published: February 2022

The inverse Ising problem, or the learning of Ising models, is notoriously difficult, as evaluating the partition function has a large computational cost. To quickly solve this problem, inverse formulas using approximation methods such as the Bethe approximation have been developed. In this paper, we employ the tree-reweighted (TRW) approximation to construct a new inverse formula. An advantage of using the TRW approximation is that it provides a rigorous upper bound on the partition function, allowing us to optimize a lower bound for the learning objective function. We show that the moment-matching and self-consistency conditions can be solved analytically, and we obtain an analytic form of the approximate interaction matrix as a function of the given data statistics. Using this solution, we can compute the interaction matrix that is optimal to the approximate objective function without iterative computation. To evaluate the accuracy of the derived learning formula, we compared our formula to those obtained by other approximations. From our experiments on reconstructing interaction matrices, we found that the proposed formula gives the best estimates in models with strongly attractive interactions on various graphs.
Approximate-analytical solutions of the quadratic Logistic differential model via SAM
Authors: Edeki S.O. , Fadugba S.E. , Udjor V.O. , Ogundile O.P. , Dosunmu D.A. , Ugbenu O. , Akindele N. , Zelibe S.C. , Kehinde T.O. , Jonah B.A.
Published: February 2022

This paper applies the novel Successive Approximation Method (SAM) for the solution of the quadratic Logistic Differential Model (LDM). To confirm the reliability of the method, illustrative examples are considered, and it is remarked that the approximate-analytical solutions of the considered cases are computed with ease. The proposed technique is used directly, without transformation, discretization, linearization, or any restrictive assumptions.
Analysis of Exponential–Polynomial Single Step Method for Singularly Perturbed Delay Differential Equations
Authors: Fadugba S. E , Vinci Shaalini J. , Ogunmiloro O.M. , Okunlola J.T. , Oyelami F.H.
Published: February 2022

This research presents Exponential – Polynomial Single Step Method (EPSSM), which uses non-linear polynomial interpolating function to solve Singularly Perturbed Delay Differential Equations (SPPDDEs). The stability polynomial of the method is obtained. The Local Grid Search Algorithm termed LGSA is applied in determining the stability region. The efficiency of these methods is compared with the other two numerical methods, namely Runge-Kutta Method (RKM) and Rational Single Step Method (RSM) through two examples of Singularly Perturbed Delay Differential Equations (SPPDDEs).
Homotopy Analysis Method for Fractional Barrier Option PDE
Authors: Fadugba S. E , Edeki S. O.
Published: February 2022

This paper proposes a fractional numerical study on Time-Fractional Barrier Option Model (T-FBOM) via highly convergence solution series method known as Homotopy Analysis Method (HAM). Furthermore, the pricing formula for T-FBOM was obtained. The performance of the method on some illustrative examples has been considered. The results obtained were compared with some existing approaches.
Structural and electronic properties of silver-adsorbed silicene nanoribbons: A first-principles study
Authors: Nguyen Thanh Tung
Published: February 2022

The geometrical and electrical features of Ag adsorption armchair silicene nanoribbons structure have been investigated using first-principles calculations. The findings reveal that the bandgap of doped Ag has changed, as it does for chemical adsorption on the surface of ASiNRs; this material became metallic at the valance band contact fermi level, with a mean bandgap of 0 eV. Furthermore, the survey to discover the best height 6.39 of Ag and 2.26 bond length Si-Si and Si-Si-Si bond angle 115015’ with structural stability near to the pristine situation has shown promising results for developing novel spintronic and optoelectronic materials in the future.
Application of microcontroller and Blynk for cultured cordyceps
Authors: Nguyen Thanh Tung
Published: February 2022

Cordyceps is a precious herb in the world; it was discovered in the Tibetan Plateau of China. It has many good uses for human health as used to replenish the kidney and soothe the lung for the treatment of fatigue, night sweating, homosexualities, hyperglycemia, hyperlipidemia, asthenia after severe illness, respiratory disease, renal dysfunction and renal failure, arrhythmias, and other heart diseases, and liver disease. Due to the production of natural cordyceps exploited each year is increasingly scarce and depleted in recent times. Therefore currently, the cultivation of this herb has been applied to meet the higher demand of the market. Using microcontrollers to monitor and manage environmental parameters such as light, temperature and humidity, and soil moisture, we have produced medicinal substances from cordyceps of similar high quality as natural products.
Research, Design and Manufacturing of a Prototype Tidal Generator
Authors: Phu Huynh Minh , Nguyen Thanh Tung
Published: February 2022

This paper talks about the research, design, and manufacturing of a tidal power generator prototype. This model is built to take advantage of tidal changes in the Southwest region of Vietnam. Here, the Mekong River has a tidal regime with high water and low water level every day. The difference in potential energy between the high tide and the low tide is utilized to generate the kinetic energy of the blades of the tidal generator turbine. The generated electricity will be stored in a lithium battery, combined with a system that transmits information to the phone via Bluetooth.
Design of a Passive Radar based on RTL-SDR technology with coherent dual channel
Authors: Mediavilla Juan Romero , Espinoza Cristian Arias , Espinosa Alex Pachacama , Salazar Franklin
Published: February 2022

In this research, a passive radar aimed at the detection of unmanned aerial vehicles was developed. As a UAV navigates at low altitudes and high speeds, RTL-SDR modules are used that with the help of two antennas, one directional and one reference, the position of the object is detected through bounce and signal discrimination, for which several tests were carried out in based on frequencies that are in the FM range. For this, GNU radio is used and data processing with Python in the Anaconda guide that facilitates obtaining data visually through a video of the frequency of the Doppler effect vs the distance in kilometers. Also, mention is made of the synchronization arrangement that is established between the RTL-SDR modules based on their oscillator.
A Note on Analytical Roots of the Navier-Stokes Equation
Authors: Akinlabi G. O. , Edeki S. O. , Braimah J.A.
Published: February 2022

A new approach called the Generalised Picard Iteration Sch eme (GPIS) is used to solve the Navier-Stokes equations in this paper. The solutions are organized in a series with components that are readily computed. Because it delivers the exact solution to the solved issue with minimal computing effort while retaining a high degree of accuracy, this method appears to be extremely adaptable, efficient, effective, and dependable. It is not necessary to identify Lagrange multipliers. As a result, the presented method is recommended for dealing with higher-order linear and non-linear models.
Al doping in germanene nanoribbons in the presence of an external electric field
Authors: Ngoc Hoang Van
Published: February 2022

Germanene by description, is a two-dimensional material with many different properties from graphene. Germanene also has a honeycomb hexagonal form but it is not a planar structure. Germanene nanoribbons (GNRs) are created from germanene with edges that have been changed by other atoms; in this study, two of the GNRs’ edges have been modified by hydrogen. The density of states (DOS), energy formation, and band structure of the system are computed, displayed, and studied using density functional theory (DFT). Due to the presence of hydrogen at the two edges, GNRs have a narrow band gap. This research will look into Al doping in GNRs with the system being immersed in a 0.5V/Angstrom external electric field. Two configurations are examined in this section: the top configuration and the valley configuration. The doped configurations do not break up in the electric field, and both configurations become semi-metals with bands crossing the Fermi level. This research lays the groundwork for future applications in nanochip technology
Application of solar energy and microcontroller for automanagement of road train tracks crossing barriers
Authors: Nguyen Thanh Tung , Azizah
Published: February 2022

Traffic safety is a legitimate and vital necessity in the current life of everyone in the world. For developed countries, the transport infrastructure system is basically invested, the traffic law is also stable due to the process of testing and applying for a long time. For developing countries, by studying the Vietnam database, we assess that the reality of road traffic in general and railways, in particular, is still quite inadequate. Although the Government has actively applied many measures, people are still insecure when traveling on the road because there are still many unfortunate accidents every day. In particular, there are many places where people open new roads to cross the tracks, causing traffic jams and affecting people’s lives and properties. In this project, we use solar panels to power the microcontroller circuit to work. They have the function of alarming, closing, and opening barriers when trains pass by to reduce loss of life and property from accidents, combined with the use of solar energy to make installation easier in mountainous areas, on the other hand, contribute to environmental protection in the future.
On Non-Linear Non-Gaussian Autoregressive Model with Application to Daily Exchange Rate
Authors: Adedotun A. F. , Olatayo T. O. , Odekina G. O.
Published: February 2022

The most often used distribution in statistical modeling follows Gaussian distribution. But many real-life time series data do not follow normal distribution and assumptions; therefore, inference from such a model could be misleading. Thus, a reparameterized non-Gaussian Autoregressive (NGAR) model that has the capabilities of handling non-Gaussian time series was proposed, while Anderson Darling statistics was used to identify the distribution embedded in the time series. In order to determine the performance of the proposed model, the Nigerian monthly exchange rate (Dollar-Naira Selling Rate) was analyzed using proposed and classical autoregressive models. The proposed model was used to determine the joint distribution of the observed series by separating the marginal distribution from the serial dependence. The maximum Likelihood (MLE) estimation method was used to obtain an optimal solution in estimating the generalized gamma distribution of the proposed model. The selection criteria used in this study were Akaike Information Criterion (AIC). The result revealed through the value of the Anderson Darling statistics that the data set were not normally distributed. The best model was selected using the minimum values of AIC value. The study concluded that the proposed model clearly shows that the non-Gaussian Autoregressive model is a very good alternative for analyzing time series data that deviate from the assumptions of normality and, in particular, for the estimation of its parameters.
Stability Analysis of a Nontrivial Solution for Delayed Nicholson Blowflies’ Model with Linear Harvesting Function
Authors: Ezekiel I D , Iyase S A , Anake T A
Published: February 2022

The study investigates stability analysis of Nicholson-blowflies’ equation with a linear harvesting function, where sufficient conditions are obtained for nontrivial equilibrium of a delayed model using the corresponding characteristic equation and Hopf bifurcation analysis. The Hopf bifurcation is studied for the qualitative character of the dynamical system, and conditions for the existence of periodic oscillation are identified. The periodic orbit of the model is equally investigated, from which further chaotic results are obtained using numerical example via MATLAB software. The study supplements theoretical improvement to earlier results obtained in the literature.
Design of Pointing Control Mechanism for Spacecraft Antenna Communication
Authors: Li Qiuyuan , Wang Shuquan , Zhang Long
Published: February 2022

Satellite antennas are widely used in satellite communications and now have become an indispensable part of satellite. It affects and restricts the performance and functions of the entire wireless communication system. Flexible pointing and low power consumption are required for antennas installed on satellites, which makes the design of the pointing mechanism of the satellite antenna more challenging. This paper focuses on the design and analysis of the pointing control mechanism to help improve the flexibility of satellite communication. An optimized structure consisting of spring hinge mechanism, manipulator arm and universal adjustment mechanism is proposed. The material selection and mechanical analysis are also made. Finally, the pointing angle is described based on the mathematical model of the pointing control mechanism.
Development of an Underwater Detection Robot
Authors: Wang Ruilin , Li Zhiqing , Ma Shugen , An Xiaosong
Published: February 2022

The ocean contains huge valuable resources, due to the huge pressure in the deep water and the danger of diving, human development is very little. In this paper, we design a small underwater observation robot, which can replace human beings to dive into deep water, detect the deepwater area and sample the water quality. Following the principle of fish diving, the robot uses the piston bucket to pump water and drain water to change its gravity to achieve floating and diving. The main propeller at the tail provides the main driving force. The robot turns by propellers on both sides working at different speeds and propellers can change the thrust direction to provide assist force in the process of diving and floating. The structure design of the tumbler(the design of anti-roll) ensures the anti-interference ability of the robot to the wind and wave. In addition, the robot can be equipped with cameras, depth sensors, temperature and humidity sensors, and other sensors to achieve efficient underwater data sampling. The depth sensor, propeller, and pumping piston are used to control the hovering depth of the robot. The ROV can record good quality of video if provided with proper video graphic tool. The design of ROV which we have conceptualize, is handy and can be powered by 24V DC power which can be easily available at remote location. The experimental results verify the structural reliability of the underwater detection robot and provide a new mobile mechanism platform and a new idea for deep-sea exploration and scientific research.
Wheat Canopy Cover Estimation by Optimized Random Forest and UAV Multispectral imagery
Authors: Zhang Tianxiang , Liu Yan , Li Jiangyun
Published: February 2022

Canopy cover estimation is widely applied to reflect crop status in agriculture research and management. In particular, an accurate CC estimation is beneficial for crop model calibration, providing high-accuracy observations. Recent solutions on CC are drawn by experimental regression or basic machine learning classifier because CC estimation can be treated as a wheat/non-wheat segmentation task. However, the appearance of hyperparameters in such machine learning algorithms impairs the segmentation performance. In this paper, by the means of UAV multispectral imagery, Bayesian optimization based Random Forest approach is selected to tune the uncertain hyperparameters accurately and robustly, providing a novel way on CC estimation. Experimental results collected in Yangling experiment field by the RedEdge camera on DJI M100 UAV are to evaluate the proposed method. Comparative studies show that the overall accuracy can reach up to 99.9%, promoting 0.2% in comparison with basic Random Forest. Therefore, integrating optimized Random Forest and UAV multispectral imagery can be applied in CC estimation at farmland scales.