bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thin-film lithium niobate-on-insulator (LNOI) shear horizontal surface acoustic wave resonators
Authors: Hsu Tzu-Hsuan , Tseng Kuan-Ju , Li Ming-Huang 
Published: March 2021

Abstract
This work investigates the design methodology to obtain large electromechanical coupling factor (

k

eff

2

) and high quality factor (Q) of shear-horizontal surface acoustic wave (SH-SAW) resonators based on the thin-film lithium niobate-on-insulator (LNOI) technology. The guided SH wave can be excited through interdigital transducers and propagate at the very surface of the material stackings. Such a guided SH wave in LN/SiO2 double layer structure is expected to offer high

k

eff

2

by confining the elastic strain energy in the piezoelectric thin film. To capture the optimum design window for high-performance LNOI SH-SAW devices, the impact of electrode material and its thickness on the

k

eff

2

dispersive characteristics are intensively investigated by finite element method (FEM). In this study, various one-port resonators with wavelengths from 2.8 μm to 8 μm were fabricated on a LNOI wafer with LN and SiO2 thickness of 0.7 and 2 μm, respectively. The 100 nm thick gold film was chosen as the electrode of the devices, which demonstrate a similar

k

eff

2

dispersive behavior to the FEM simulation with small discrepancy. Among the measurement results over several tested samples, a high-

k

eff

2

of 25.5% and Q of 960 was recorded at a resonance frequency of 581 MHz (FOM =

k

eff

2

⋅
Q

= 245), revealing great potential for the application of wide-band frequency selection in telecommunications.
Two-center interference effect on molecular ionization and Rydberg-state excitation
Authors: Liu MingQing , Shu Zheng , Hu ShiLin , Chen Jing 
Published: March 2021

Abstract
We have studied ionization and excitation of model molecules possessing different initial states (1sσ

g
and 1sσ

u
) in 800 nm laser pulses by numerical solution of three-dimensional time-dependent Schrödinger equation and quantum models. Calculations of two methods show good agreement. It is found that the locations of the peaks of total Rydberg-state probability vs laser intensity do not coincide for different initial states, which is ascribed to the fact that the relative contributions from Rydberg states change due to the difference of the ionization time distributions for different initial states induced by the two-center interference effect. In addition, it is demonstrated that the suppression of ionization is more obvious than that of excitation compared the results of 1sσ

u
state with those of 1sσ

g
state, which is attributed to the distinct interference effects for molecular ionization and excitation in strong laser fields.
Post-collision interaction effect in THz-assisted Auger decay of noble gas atoms
Authors: Bermúdez Macias I J , Düsterer S , Ivanov R , Frühling U , Kabachnik N M 
Published: March 2021

Abstract
Auger electron spectra were simulated in the presence of a terahertz streaking field to study post-collision interaction (PCI) effects in the time-evolution of photoinduced Auger decays. The PCI is characterized by the ratio of the spectral line width for Auger electron emission in opposite directions with respect to the THz-field. These calculations have been performed using the analytical semiclassical model developed by Bauch and Bonitz (2012 Physical Review A
85 053416). The results are shown for Ne(KLL), Ar(LMM), Kr(MNN) and Xe(NOO) Auger transitions whereby different possible experimental conditions were evaluated.
Extraction of Ps-formation cross-sections from single-centre positron-scattering calculations
Authors: Utamuratov R , Fursa D V , Kadyrov A S , Abdurakhmanov I B , Bray I 
Published: March 2021

Abstract
Positron scattering on atomic and molecular targets is a two-centre problem due to the possibility of rearrangement (Ps-formation) processes. In certain kinematic regions, single-centre expansion methods can be applied to two-centre scattering problems. In such approaches, however, information about Ps-formation and direct ionization processes are combined into excitation amplitudes of positive-energy pseudostates. In this report we show that Ps-formation amplitudes can be extracted using the total scattering wave function, which we reconstruct from single-centre convergent close-coupling calculations. The method is applied to positron scattering from hydrogen and lithium atomic targets. Excellent agreement with the two-centre theoretical benchmark results show the validity of the proposed technique.
The dose magnifying glass quality assurance system for daily proton therapy range verification
Authors: Debrot E , Mundy D , Guatelli S , Petasecca M , Perevertaylo V , Beltran C , Rosenfeld A B 
Published: March 2021

Abstract
Proton therapy has a distinct dosimetric advantage over conventional photon therapy due to its Bragg peak profile. This allows greater accuracy in dose delivery and dose conformation to the target, however it requires greater precision in setup, delivery and for quality assurance (QA) procedures. The AAPM TG 224 report recommends daily range and spot position checks with tolerance on the order of a millimetre. Daily QA systems must therefore be efficient for daily use and be capable of sub-millimetre precision however few suitable commercial systems are available. In this work, a compact, real-time daily QA system is optimised and characterised for proton range verification using an ad-hoc Geant4 simulation. The system is comprised of a monolithic silicon diode array detector embedded in a perspex phantom. The detector is orientated at an angular offset to the incident proton beam to allow range in perspex to be determined for flat proton fields. The accuracy of the system for proton range in perspex measurements was experimentally evaluated over the full range of clinical proton energies. The mean R
100, R
90 and R
80 ranges measured with the system were accurate within ±0.6 mm of simulated ranges in a perspex phantom for all energies assessed. This system allows real-time read-out of individual detector channels also making it appropriate for temporal beam delivery diagnostics and for spot position monitoring along one axis. The system presented provides a suitable, economical and efficient alternative for daily QA in proton therapy.
Fractional-order model representations of apparent vascular compliance as an alternative in the analysis of arterial stiffness: an in-silico study
Authors: Bahloul Mohamed A , Laleg Kirati Taous-Meriem 
Published: March 2021

Abstract

Objective. Recent studies have demonstrated the advantages of fractional-order calculus tools for probing the viscoelastic properties of collagenous tissue, characterizing the arterial blood flow and red cell membrane mechanics, and modeling the aortic valve cusp. In this article, we present novel lumped-parameter equivalent circuit models for apparent arterial compliance using a fractional-order capacitor (FOC). FOCs, which generalize capacitors and resistors, display a fractional-order behavior that can capture both elastic and viscous properties through a power-law formulation. Approach. The proposed framework describes the dynamic relationship between the blood-pressure input and the blood volume, using linear fractional-order differential equations. Main results. The results show that the proposed models present a reasonable fit with the in-silico data of more than 4000 subjects. Additionally, strong correlations have been identified between the fractional-order parameter estimates and the central hemodynamic determinants as well as the pulse-wave velocity indexes. Significance. Therefore, the fractional-order-based paradigm for arterial compliance shows notable potential as an alternative tool in the analysis of arterial stiffness.
Quantum coherence resonance
Authors: Kato Yuzuru , Nakao Hiroya 
Published: March 2021

Abstract
It is shown that coherence resonance, a phenomenon in which regularity of noise-induced oscillations in nonlinear excitable systems is maximized at a certain optimal noise intensity, can be observed in quantum dissipative systems. We analyze a quantum van der Pol system subjected to squeezing, which exhibits bistable excitability in the classical limit, by numerical simulations of the quantum master equation. We first demonstrate that quantum coherence resonance occurs in the semiclassical regime, namely, the regularity of the system’s oscillatory response is maximized at an optimal intensity of quantum fluctuations, and interpret this phenomenon by analogy with classical noisy excitable systems using semiclassical stochastic differential equations. This resonance persists under moderately strong quantum fluctuations for which the semiclassical description is invalid. Moreover, we investigate even stronger quantum regimes and demonstrate that the regularity of the system’s response can exhibit the second peak as the intensity of the quantum fluctuations is further increased. We show that this second peak of resonance is a strong quantum effect that cannot be interpreted by a semiclassical picture, in which only a few energy states participate in the system dynamics.
Stealth dark energy in scordatura DHOST theory
Authors: Gorji Mohammad Ali , Motohashi Hayato , Mukohyama Shinji 
Published: March 2021

Abstract
A stealth de Sitter solution in scalar-tensor theories has an exact de Sitter background metric and a nontrivial scalar field profile. Recently, in the context of Degenerate Higher-Order Scalar-Tensor (DHOST) theories it was shown that stealth de Sitter solutions suffer from either infinite strong coupling or gradient instability for scalar field perturbations. The sound speed squared is either vanishing or negative. In the first case, the strong coupling scale is zero and thus lower than the energy scale of any physical phenomena. From the viewpoint of effective field theory, this issue is naturally resolved by introducing a controlled detuning of the degeneracy condition dubbed scordatura, recovering a version of ghost condensation. In this paper we construct a viable dark energy model in the scordatura DHOST theory based on a stealth cosmological solution, in which the metric is the same as in the standard ΛCDM model and the scalar field profile is linearly time-dependent. We show that the scordatura mechanism resolves the strong coupling and gradient instability. Further, we find that the scordatura is also necessary to make the quasi-static limit well-defined, which implies that the subhorizon observables are inevitably affected by the scordatura. We derive the effective gravitational coupling and the correction to the friction term for the subhorizon evolution of the linear dark matter energy density contrast as well as the Weyl potential and the gravitational slip parameter. In the absence of the scordatura, the quasi-static approximation would break down at all scales around stealth cosmological solutions even if the issue of the infinite strong coupling is unjustly disregarded. Therefore previous estimations of the subhorizon evolution of matter density contrast in modified gravity in the literature need to be revisited by taking into account the scordatura effect.
Numerical simulations and analysis of the zig-zag maneuvers of an oil tanker based on a body-force propeller
Authors: Hao Hao , Weimin Chen , Zixin Wu 
Published: March 2021

Abstract
The course change quality is a crucial measure of ships’ maneuverability and is closely related to the ship navigation safety. Research on zig-zag motion of ships is essential to voyage safety. STARCCM+ based on the ship 6-DOF motion and overset grid technology are used to numerically simulate the zig-zag maneuver of an oil tanker. To simulate the zig-zag motion, a body-force propeller model is adopted instead of the real propeller. The rotation speed of virtual propeller is controlled to achieve the steady self-propulsion state of the ship model and then the rudder turns from 10° to -10° according to the orientation of the ship model. By solving viscous flow field, the motion state and detailed flow field information of the ship model are presented. To verify the accuracy of numerical prediction results, ship model test is launched. Through comparison of results, the numerical simulation can provide reference for preliminary assessment for the course change quality of ships.
A study of particle separation system of hazardous materials collection truck
Authors: Zhou Shuwen , Yang Shuo , Wang Yu 
Published: March 2021

Abstract
A three-stage dust removal technology is adopted in the hazardous materials collection truck proposed in this paper, including the inertial separator in the main storage tank, the cyclone separator and the pleated element filter. The inertial separator housed in the main tank is designed to be detachable to avoid inconvenience caused when collecting liquid hazardous materials. The leaked hazardous materials pulled by vacuum enter the main tank with the air flow, and the heavy particles of the hazardous materials are intercepted in the main tank under the action of the inertial separator. The remaining hazardous particles are removed from the air flow in the cyclone separator. The remaining particles of very small size and density enter pleated element filter, and most of the particles are intercepted by the filter cartridge. The particle separation process is established in this paper and its fluid dynamics simulation analysis is carried out. The simulation results show that the particle separation system proposed in this paper can separate and intercept the collected solid hazardous materials, avoiding secondary pollution to the environment.
Study on rollover risk of the tanker with different liquid filling coefficient in emergency turn
Authors: Zuo Yonggang , Zhang Zhen , Yang Jing , Zhao Xiang 
Published: March 2021

Abstract
3D simulation model of petroleum sloshing in off-road tanker based on the VOF method, moving coordinate system and the actual size of the internal petroleum and tank structure is established in this paper. The mathematical model of the petroleum sloshing in tank is established, lateral rollover torque of petroleum sloshing in emergency turning is researched, the effects of the cross section shape and baffle area in tank on the dynamic characteristics of petroleum sloshing is studied.
The mega city of Tehran water quantity assessment based on DPSIR model
Authors: Sarmadi Hajar , Salehi Esmaeil , Kusari Nick 
Published: March 2021

Abstract
One of the most important factors of urbanization is healthy water supplement. Tehran as a megacity suffers from not only overcrowding but also lack of water. Tehran water supplements are both groundwater and surface resources. Surface water resources are including Karaj, Lar, Latian, Taleghan Dams and Tehran-Karaj Plain is its groundwater resources. Therefore, Tehran-Karaj Plain is considered as a target area in this study. The target area is located between 51°05′ and 51°10′ longitude and 35°02′ and 35° 57′ latitude with approximately 2704Km2. The urban rivers are originated from the Alborz Mountains and received urban runoff, and secondary effluent of Tehran Wastewater Treatment Plants which ultimately collected in Bande Alikhan in the southern part of Tehran. The evaluation of Tehran water quantity by DPSIR Model is considered in this paper. Driving forces, Pressures and the Status of water quantity will represent and their impacts on the city will also investigate.
The effect of time discretization on the propeller hydrodynamic performance simulation in self-propulsion and open water conditions
Authors: Fan Yang , Kunpeng Chen , Weimin Chen , Guoxiang Dong 
Published: March 2021

Abstract
Numerical simulation technology is widely used in the field of naval architect and marine engineering. The flow induced by the propeller is unsteady. In order to demonstrate the effect of time discretization format and time step on the simulation of the flow, this paper takes an oil tanker and its propeller as the research objects, and simulations have been conducted by using OpenFoam. By comparing the thrust, torque and the vortex after the propeller, the effects of the time discretization format and time step on the numerical simulations are analyzed. This paper believes that changing the discretization format of the time term while keep the time step unchanged has little effect on the calculation results in the condition of open water test simulation. It is beneficial to simulate of the vortex after the propeller hub by using a small time step. The first-order backward Euler discretization format in the condition of self propulsion simulation is recommended. If the error of thrust compared with experiment data is larger than expected, the second-order discretization format should be considered. In order to improve the accuracy of numerical simulation, a smaller time step could be considered.
RANS CFD seakeeping simulation for an 82k DWT vessel in head and oblique waves
Authors: Kunpeng Chen , Fan Yang , Yunlong Du 
Published: March 2021

Abstract
Numerical seakeeping simulation of an 82k DWT vessel is carried out to investigate its ship motions and added resistance in head waves and oblique waves. By applying the Reynolds-Average Navier-Stokes (RANS) calculations, both viscous and rotational effects are included in current seakeeping simulation. In this study the Navier-Stokes and continuity equations are the governing equations and they are discretized by finite volume method. The free surface is tracked by volume of fluid (VOF) method, volume fractions were used together with fluid’s incompressibility. The turbulence model was k - ω SST. In this simulation, Wave Forcing technic is applied to reduce the size of the computational domain and reduce the computing resources needed. The solution of the 3D Navier-Stokes equations is forced towards a solution in the boundary zone, this forcing also eliminates problems that are associated with reflections of surface waves at boundaries. The validation studies are carried out by comparing the current simulations’ results with towing tank experiments. This study established the viscos method with 3 degree of freedom for evaluating 82k DWT vessel’s seakeeping performance. The authors also gave the suggested length of the wave forcing area for the 82k DWT ship.
Full scale KCS self-propulsion simulation using different propulsion models
Authors: Yu Jiawei , Wu Zhiqi , Wang Luqun , Zhou Yujie , Zhang Zhiguo 
Published: March 2021

Abstract
It is critical to be able to estimate the full-scale ship self-propulsion, since the more real sailing performance of the ship can be assessed. Results of scaling model are used to predict full-scale self-propulsion performance. However, the difference between the full-scale prediction and reality would be caused by scale effect. URANS simulations is conducted to predict self-propulsion of a full-scale KRISO Container Ship with the propeller KP505. Design speed is selected as simulation working condition according to Gothenburg 2010. In house CFD code HUST-Ship will be used to solve RANS equation coupled with two degrees of freedom (2DOF) solid body motion equations including heave and pitch. RANS equations are discretized by finite difference method and solved by PISO algorithm. The discretized propeller model and improved body-force model are used as the propulsion models. Grid and time step sensitivity analysis of full-scale propeller and hull is conducted separately. The self-propulsion indexes of full-scale simulation are compared with the extrapolation of model experimental data and full-scale simulation results from literatures. The prediction self-propulsion indexes based on different propulsion models are compared and discussed.
Ocean – A vast reserve of renewable energy
Authors: Shaw Surupa 
Published: March 2021

Abstract
Ocean has an immense potential to be exploited as an energy resource. The advancement in the renewable energy technologies have opened several avenues for exploring the ocean to combat the rising concern of the global climate change and the worldwide energy supply. The renewable energy is the inevitable choice for a sustainable economic growth in times of economic crisis, and the ocean environment is an inadequately utilized domain for the application of renewable technologies. This paper strongly focuses on the importance of the various forms of energy from the ocean environment like wave energy, wind energy, tidal energy, ocean thermal energy. A strong assessment of the current renewable technologies that can be strategically deployed to the ocean environment with minimal influence on the marine ecosystem, has been presented here. The current work targets the ocean environment for its availability as a promising resource to assist in the effort of tackling the world energy issues. The history of continued research on the requirement and consequence of enhancing the already existing renewable technologies, in the ocean has been traced in this paper. This study provides an overview of the key parameters responsible for the accurate choice of ocean energy harnessing site, that will eventually serve as an excellent reference for the rational deployment guidelines of the future renewable technologies. Ocean energy through waves, tides and thermal gradients is a powerful source of abundant clean, renewable energy and the essential information needed for the conversion of the ocean energy to usable form is presented in this paper.
Experimental investigation on the effects of machining parameters on surface integrity in form grinding of rail material
Authors: Liu Peijie , Quan Yanming , Wan Junjie 
Published: March 2021

Abstract
Rail grinding is an essential measure for the maintenance of railway infrastructure, and the machined surface integrity of rail material plays a crucial role in ensuring the safety, stability and service performance of the railway network. In this paper, an electroplated diamond grinding wheel was employed to re-profile the rail surface. Meanwhile, single-factor experiments on the form grinding of rail material were designed and carried out by virtue of the self-developed rail grinding platform under dry grinding condition based on proper machining parameters. The effects of machining parameters on the surface roughness, subsurface micro-hardness, plastic deformation, and surface morphology were investigated, respectively. The experimental results revealed that the surface roughness and subsurface micro-hardness increase with the increase of feed speed and grinding depth, while decrease with the increase of wheel peripheral speed. The thickness of subsurface plastic deformation layer and the degree of plastic flow increase with the increase of grinding depth, and the thickness of subsurface plastic deformation layer ranges from 7 μm to 14 μm with the change of grinding depth.