bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recovery of coefficients for a weighted p-Laplacian perturbed by a linear second order term
Authors: Cârstea Cătălin I , Kar Manas 
Published: November 2020

Abstract
This paper considers the inverse boundary value problem for the equation ∇ ⋅ (σ∇u + a|∇u|
p−2∇u) = 0. We give a procedure for the recovery of the coefficients σ and a from the corresponding Dirichlet-to-Neumann map, under suitable regularity and ellipticity assumptions.
Feasibility study of a micro-electro-mechanical-systems threshold-pressure sensor based on parametric resonance: experimental and theoretical investigations
Authors: Pallay Mark , Daeichin Meysam , Towfighian Shahrzad 
Published: November 2020

Abstract
A tunable threshold pressure sensor based on parametric resonance of a microbeam subjected to electrostatic levitation is proposed. Parametric excitation can trigger a large amplitude vibration at twice the natural frequency if the magnitude of the driving force is large enough to overcome energy loss mechanisms in the system such as squeeze film damping. This causes a temporarily unstable response with a significant gain in oscillation amplitude over time until it is eventually capped by nonlinearities in the force or material or geometric properties. The instability divides the frequency region into two regions: distinct responses bounded by the system non-linearity, and trivial responses with very low oscillation amplitudes. It is shown experimentally that the appearance of parametric resonance depends on the pressure, which influences the amount of energy loss from squeeze film damping. Therefore, the distinct difference in the vibration amplitude can be used to detect when the pressure passes a threshold level. The activation of parametric resonance also depends on the amplitude of the driving force (

V

ac

). This voltage amplitude can be set to trigger parametric resonance when the pressure drops below a predetermined threshold. A reduced-order model is developed using the Euler–Bernoulli beam theory to elucidate the non-linear dynamics of the system. The simulation results from the mathematical model are in good agreement with the experimental data. The advantages of the proposed sensor over pull-in based sensors are its reliability and improved resolution from a large signal-to-noise ratio.
Quantum secrecy in thermal states III
Authors: Ghesquière Anne , Varcoe Benjamin T H 
Published: November 2020

Abstract
In this paper we expanded the security of a central broadcast protocol using thermal states to the case in which the eavesdropper controls the source. Quantum secrecy in a continuous variable central broadcast scheme is guaranteed by the quantum correlations present in thermal states arising from the Hanbury Brown and Twiss effect. This work allows for a method of key exchange in which two parties can agree a key as long as both can detect the same source and they are within the spatial coherence length of the source. This is important because it allows quantum secure key exchange with only minimal changes to existing infrastructure.
Short-time emission of higher-angular-momentum photons by atomic transitions
Authors: Lei Meng Lok , Debierre Vincent 
Published: November 2020

Abstract
The short-time regime of spontaneous light emission by few-electron ions is examined in detail, with a specific emphasis on the angular momentum of the emitted light. It is found that, in general, photons carrying a higher angular momentum are emitted with important probabilities, at short times, in transitions that are not of the electric dipole type. The probability of emission of such photons is found to be parametrically non-negligible in this time regime, and even numerically dominant for some cases. It is also found that, in all time regimes, the emission of electric 2
n+1-pole fields is typically numerically dominant over the emission of magnetic 2
n
-pole fields by many orders of magnitude. These results refine and deepen our understanding of the emission of angular momentum-carrying light by simple atomic systems.
Hyperfine splitting and lifetime of the positronium lowest level in a strong electric field
Authors: Milošević M Z , Bunjac A , Popović D B , Simonović N S 
Published: November 2020

Abstract
When placed in an external electric field, positronium, which already has a finite lifetime due to annihilation, becomes additionally unstable due to field-induced ionization. Calculations of the ionization rate using ab initio methods show that, compared to annihilation, it becomes dominant in the range of field strengths belonging to over-the-barrier ionization (OBI) regime. On the other hand, the hyperfine splitting of the positronium lowest level decreases in the tunnelling domain, taking at the beginning of the OBI domain a value that is about 20% lower than the field-free value. As the field strength increases further, this splitting varies rather slowly, but here an additional splitting of triplet levels occurs, whose rate is comparable to this variation. Finally, it is demonstrated that the lowest energy levels and ionization rates for the hydrogen atom and positronium, determined within the gross structure, are related to scaling transformations.
Experimental re-evaluation of proton penetration ranges in GaAs and InGaP
Authors: Yaccuzzi E , Di Napoli S , Di Liscia E J , Suárez S , Alurralde M , Strittmatter A , Pla J , Giudici P 
Published: November 2020

Abstract
Multijunction solar cells based on InGaP and GaAs materials are currently the state of the art for space applications due to their high efficiencies. However, space is a hazardous environment with different energetic particles that degrade the solar cell efficiency, hence decreasing the satellite lifetime. To gain insight in the behaviour of the solar cells under particle bombardment, we study the effect of radiation on InGaP and GaAs layers, constituent materials of III–V solar cells. By means of photoluminescence and Raman spectroscopy we investigate changes of the optical parameters in the irradiated region, and compare the results with simulations obtained with the code Stopping and Ranges of Ions in Matter. The proton ranges obtained from experiments differ considerably from the predicted by the simulations in the case of InGaP. We demonstrate that this discrepancy increases monotonously with proton energy. We discuss the possible origin of the differences in terms of electronic orbitals and bonding structure of the simulated compound, and the implications in the design of solar cells for space applications.
A safe and efficient LIDAR-based navigation system for 4WS4WD mobile manipulators in manufacturing plants
Authors: Meng Jie , Wang Shuting , Xie Yuanlong , Li Gen , Zhang Xiaolong , Jiang Liquan , Liu Chao 
Published: November 2020

Abstract
The safe and efficient autonomous navigation of mobile manipulators is still challenging in harsh manufacturing environments with dynamic obstacles and narrow spaces. This paper addresses that challenge by proposing an industrial-grade LIDAR-based navigation system for four-wheel-steering and four-wheel-driving mobile manipulators and focuses on enhancing the system’s safety and efficiency in manufacturing plants. On one hand, using an efficient soft-evidence unscented distance filter, a robust localization method is presented to eliminate dynamic interference. The variation results of scan matching are ingeniously applied to formulate a practical localization-failure-detection strategy, therefore improving localization safety under confusing working conditions. On the other hand, an efficient path-graph-based trajectory-planning method is proposed, which can instantly generate a trajectory in a safe and effective search space. Considering the regional connectivity and movement characteristics of the 4WS4WD mobile manipulator, a novel path graph is designed to construct the search space. Even in a large-scale scenario, a robot can obtain the desired trajectory within 5 ms. Ultimately, some core modules, such as a safety module and a fault-tolerant control module are integrated to form a comprehensive navigation system. The simulated and real experimental results prove the excellent performance of our navigation system, which has been successfully applied in many real-world scenarios.
A low-cost apparatus to measure the Seebeck coefficient
Authors: Mulla Rafiq , Rabinal M K 
Published: November 2020

Abstract
In this paper, a very simple and low-cost setup design is described for the Seebeck coefficient measurement of the disc and rod-shaped specimens. The setup has been tested for its reliable working by measuring the Seebeck coefficients of standard samples; measured values match with the literature. The setup can be built with commonly available raw materials in a short time. The tool is portable and can be used as a testing tool or to demonstrate the thermoelectric effect in different materials.
Utilizing shared information between gradient-spoiled and RF-spoiled steady-state MRI signals
Authors: Sveinsson Bragi , Gold Garry E , Hargreaves Brian A , Yoon Daehyun 
Published: November 2020

Abstract
This work presents an analytical relationship between gradient-spoiled and RF-spoiled steady-state signals. The two echoes acquired in double-echo in steady-state scans are shown to lie on a line in the signal plane, where the two axes represent the amplitudes of each echo. The location along the line depends on the amount of spoiling and the diffusivity. The line terminates in a point corresponding to an RF-spoiled signal. In addition to the main contribution of demonstrating this signal relationship, we also include the secondary contribution of preliminary results from an example application of the relationship, in the form of a heuristic denoising method when both types of scans are performed. This is investigated in simulations, phantom scans, and in vivo scans. For the signal model, the main topic of this study, simulations confirmed its accuracy and explored its dependency on signal parameters and image noise. For the secondary topic of its preliminary application to reduce noise, simulations demonstrated the denoising method giving a reduction in noise-induced standard deviation of about 30%. The relative effect of the method on the signals is shown to depend on the slope of the described line, which is demonstrated to be zero at the Ernst angle. The phantom scans show a similar effect as the simulations. In vivo scans showed a slightly lower average improvement of about 28%.
Observation of a significant drop of electron density in cascaded arc argon plasma doped with oxygen gas using laser Thomson scattering
Authors: Wang Yong , Shi Jielin , Li Cong , Feng Chunlei , Ding Hongbin 
Published: November 2020

Abstract
In this work, the electron density (n
e) and electron temperature (T
e) of cascaded arc argon plasma regulated by adding electronegative oxygen gas have been investigated using laser Thomson scattering diagnostic technique. The results indicate that the addition of O2 gas causes a significant decrease of n
e, which drops from 1020 m−3 to 1017 m−3. This is mainly attributed to the dissociative recombination reaction between electrons and O2
+ molecular ions. Meanwhile, the formation of negative ions, O2
− and O−, consumes electrons and further makes n
e decrease. But, T
e remains nearly unchanged with the increase of O2 ratio from 0% to 10%. This is probably due to that the electron energy loss by the electron collisions with O2 molecules in the ground state balances the electron heating induced by the super-elastic collisions with the highly vibrational excited O2 molecules.
Simulation of the Ohkawa-mechanism- dominated current drive of electron cyclotron waves using linear and quasi-linear models
Authors: Zheng P W , He L H , Yin L , Lu X Q , Huang Q H , Zhong Y J , Deng S , Jiang X C , Gong X Y 
Published: November 2020

Abstract
Simulation on the Ohkawa-mechanism-dominated current drive (OKCD) of electron cyclotron (EC) waves is performed using TORAY-GA linear code, and the results are compared with those calculated by CQL3D quasi-linear code. It is found that the radial location of the OKCD profile is almost identical between the linear and the quasi-linear calculations. However, there are significant differences in the calculation of the total driven current

I

e
c

and the peak value of the driven current profile

j

e
c

p
e
a
k

between the two models. The

I

e
c

calculated by the CQL3D code is at least 1.4 times larger than the results from the TORAY-GA code. For the calculation of

j

e
c

p
e
a
k

, the results from CQL3D are at least 1.6 times larger than that calculated by TORAY-GA. With increasing electron temperature, the two models further enlarge the total driven current scaling factor

F
I

and the peak driven current density scaling factor

F
j

. This is mainly because the collision operator in TORAY-GA code adopts a high-speed model and does not retain the first-order Legendre expansion term for momentum conservation of electron self-collision. The quasi-linear effect does not have a significant influence on the total driven current of OKCD when the EC power level does not meet

P

r
f

MW

m

−
3

n
e

10

19

m

−
3

> 0.5. Therefore, in practical engineering, the TORAY-GA code can be used to calculate OKCD quickly and accurately by multiplying with appropriate scaling factors. The effect of momentum conservation is very important for OKCD and on-axis EC current drive (ECCD), but this effect is not important for off-axis ECCD. The results from this study show that the effects of electron trapping and the collision between resonant passing electrons and trapped electrons are responsible for the decrease in off-axis ECCD efficiency.
Fast Fourier transform-volume integral: a smart approach for the electromagnetic design of complex systems in large fusion devices
Authors: Bettini P , Torchio R , Lucchini F , Voltolina D , Alotto P 
Published: November 2020

Abstract
A volume integral (VI) equation method based on the fast Fourier transform (FFT) is proposed for the electromagnetic simulation of complex systems in large magnetic confinement fusion (MCF) devices. Such FFT-VI allows for dramatically reducing the time and the human effort required to adapt the CAD input files to models suited for electromagnetic simulations. Moreover, with FFT-VI the mesh generation is performed automatically and is very efficient and robust. The adoption of the FFT allows for significantly reducing the computation time and the memory requirements, therefore making simulations with several millions of unknowns feasible. Numerical results show that, in terms of numerical performances, the FFT-VI method applied to challenging electromagnetic problems in representative MCF devices is markedly superior with respect to the state of the art VI techniques. A sample implementation of FFT-VI is made publicly available.
Parasitic subthreshold drain current and low frequency noise in GaN/AlGaN metal-oxide-semiconductor high-electron-mobility field-effect-transistors
Authors: Takakura K , Putcha V , Simoen E , Alian A R , Peralagu U , Waldron N , Parvais B , Collaert N 
Published: November 2020

Abstract
The impact of the short gate length on the drain current and low frequency (LF) noise in GaN/AlGaN metal-oxide-semiconductor high-electron-mobility field-effect-transistors has been studied. In some short devices, a parasitic subthreshold current is observed. In this article, the origin of parasitic subthreshold currents were explored using LF noise and trapping transient measurements. The LF noise power spectral density (PSD) of the devices without parasitic drain current decreased monotonically with the decrease of the drain current, while the PSD of the device with the parasitic drain current strongly increased for lower drain current. The 1/f
1.5 noise corresponding with the parasitic leakage can be explained by the level broadening of generation-recombination centers in the GaN channel. This is confirmed by the trapping transient measurements, revealing a temperature-independent time constant, associated with the leakage path in short channel transistors, exhibiting the subthreshold humps.
Random deposition with surface relaxation model in u
v flower networks
Authors: Kim Jin Min 
Published: November 2020

Abstract
Random deposition with a relaxation model in (u, v) flower networks is studied. In a (2, 2) flower network, the surface width W(t, N) was found to grow as b ln t in the early period and follows a ln N in the saturated regime, where t and N are the evolution time and the number of nodes in the network, respectively. The dynamic exponent z, obtained by the relation z = a/b, was z ≈ 2.11(10), which is consistent with the random walk exponent d
w = 2 in the network. For u + v ⩾ 5(u ⩾ 2, v ⩾ u), i.e. the (2, 3) and (3, 3) flower networks, the surface width grows following power-law behavior with some corrections, where the growth exponent β and roughness exponent α are controlled by spectral dimension d
s and fractal dimension d
f of the substrate network.
Parallel temperature interfaces in the Katz–Lebowitz–Spohn driven lattice gas
Authors: Mukhamadiarov Ruslan I , Täuber Uwe C 
Published: November 2020

Abstract
We explore a variant of the Katz–Lebowitz–Spohn (KLS) driven lattice gas in two dimensions, where the lattice is split into two regions that are coupled to heat baths with distinct temperatures. The geometry was arranged such that the temperature boundaries are oriented parallel to the external particle drive and resulting net current. We have explored the changes in the dynamical behavior that are induced by our choice of the hopping rates across the temperature boundaries. If these hopping rates at the interfaces satisfy particle-hole symmetry, the current difference across them generates a vector flow diagram akin to a vortex sheet. We have studied the finite-size scaling of the particle density fluctuations in both temperature regions, and observed that it is controlled by the respective temperature values. Specifically, if the colder subsystem is maintained at the KLS critical temperature, while the hotter subsystem’s temperature is set much higher, the interface current greatly suppresses particle exchange between the two regions. As a result of the ensuing effective subsystem decoupling, strong fluctuations persist in the critical region, whence the particle density fluctuations scale with the KLS critical exponents. However, if both temperatures are set well above the critical temperature, the particle density fluctuations scale according to the totally asymmetric exclusion process. In addition, we have measured the entropy production rate in both subsystems; it displays intriguing algebraic decay in the critical region, while it saturates quickly at a small but non-zero level in the hotter region. We have also considered another possible choice of the hopping rates across the temperature interfaces that explicitly breaks particle-hole symmetry. In that case the boundary rates induce a net particle flux across the interfaces that displays power-law behavior, until ultimately the particle exclusion constraints generate a clogging transition to an inert state.
Thermohydraulic simulation of a channel with targets for production of radioactive isotopes in the IVV-2M nuclear reactor
Authors: Litvinov D N , Kostarev V S , Klimova V A , Tashlykov O L , Aristov N M 
Published: November 2020

Abstract
The importance of radioisotope products usage in industry, science and medicine is underlined. The necessity of safety ensuring and radiation protection optimization while transporting the containers with radioactive isotopes is postulated. The information on isotope products making in the IVV-2M nuclear reactor of Research Institute of Nuclear Materials, JSC, from the beginning of 1990-ies is given. The data on application properties of Selenium 75 isotope are presented. The requirements to the thermohydraulic conditions of Se 75 isotope production in the nuclear reactor are formulated. The stages of a solid model development of a target for Se-75 isotope production as a part of an irradiation device of IVV-2M nuclear reactor are described. The results of hydraulic simulation of the coolant flow for various ways of devices arranging in the irradiation channel of the reactor are given. The analysis of thermohydraulic processes was performed with the help of SolidWorks Flow Simulation software.
To estimate reliability of hydroaccumulator system of nuclear power plants and improve its design and reliability
Authors: Rana Abdul Awal , Samokhin DS , Shahabuddin A K M , Haque Zihad Ul , Sanam Sadbi Ahmad 
Published: November 2020

Abstract
There are around twenty branches in a Nuclear Power Plant that operate to maintain the plant and one of the most important branches of them is ‘Safety and Reliability’. Approximately forty percent of the investment is paid to ensure the safety and reliability of the plant. Goal of this research work is to estimate reliability of a mechanical system which is chosen as Hydroaccumulator System of VVER type reactor. Getting the reliability, we will be trying to improve the system and enhance its reliability. To do so, firstly, reliability is calculated from a ‘prototype reactor’s’ hot loop which is located at Obninsk Institute for Nuclear Power Engineering (INPE). Thus, calculations were done and its applications being known, then finally these formulas and experiences are being used to calculate and improve the Hydroaccumulator System’s design along with its reliability to increase the safety of the NPP.
Analysis of the vibrational monitoring data regarding VVER type reactor installation
Authors: Sanam Sadbi Ahmad , Nakhabov Alexander , Haque Zihad Ul 
Published: November 2020

Abstract
Vibrational data monitoring system is designed to observe, detect and study any vibration caused in the NPP working cycle by different factors. The objective of the work is to analyze vibrational monitoring data of the primary circuit installation of VVER reactor to acquire knowledge of the characteristics of equipment vibration. Data has been collected using displacement sensors and pressure fluctuation sensors attached to the equipment. Data processing is carried out in R software. The work gives an overall idea of the vibrational data processing, visualization and how to present it by different graphics which will help the NPP operator for taking necessary steps.
The effect of varying collimator geometry in alpha spectrometry of environmental analysis
Authors: Amoah P A , Pripachkin D A 
Published: November 2020

Abstract
Assessment of radioactive aerosols in the atmosphere has always been an important field of study due to its effects on many biological systems. The efficiency in measuring these aerosols is therefore critical to research and industrial practice, thus; the principles and methods of geometry development to improve efficiency and resolution is paramount. The aim of this study is to use numerical simulation with MATLAB to improve the resolution and detection efficiency of an alpha spectrometer with varying collimator geometries. A collimator between a radiation source and a detector plays a very important role in identifying specific radionuclides among various species in a radioactive environment. The geometric model of the collimator being considered here is that of a triangular and a hexagonal shape. To evaluate the counts, randomly obtained data using Microsoft excel was used, considering the specified boundary conditions in a two-dimensional plane. Various counts ranging from 100 to 100,000 were analyzed to obtain the results of a log efficiency curve using MATLAB. Subsequent counting efficiency curves were then determined relative to the dimensions. An average value of 0.44 ± 0.1106 was determined for the efficiency. With emphases on the apothem of the geometries being studied, the triangular shaped collimator has theoretically shown to produce a higher resolution though with a possible decrease in detection efficiency.