bluuebunny/crossref_metadata_2025_split huggingface dataset:
Strategy on choice of layback spins in figure skating
Authors: Hoo Qianying , Liu Xiaopeng , Cao Xuewei 
Published: September 2020

Abstract
Spin is an important component of figure skating, one of the most elegant events in the Winter Olympic Games. It is always presented as an example of the conservation of angular momentum in mechanics textbooks. However, the physics behind it in the actual operation is not that simple. Herein, we analyzed videos of an elite figure skater with open source video analysis. The moments of inertia of her body in six different layback positions were obtained. The average ice resistance during her spin was found to be about 26N and was put into consideration in the following calculation. Twenty-two different layback spins that score the same basic value were discussed. The initial angular momentum a skater needs when executing a spin is considered to be the largest contributor to its difficulty; the suggested easiest spin among the 22 was thus found by comparing their initial angular momentum. This paper presents a strategy that may help figure skaters achieve a high-scored layback spin efficiently, and the process itself will be an inspiring example of applying theory to practice for physics students.
Evaluation of a novel parabolic plasma electrode advantage in a triode extraction system of a helicon ion source: simulation and experiment
Authors: Khoshhal Mohammadreza , Habibi Morteza , Boswell Rod 
Published: September 2020

Abstract
An industrial type of Amirkabir helicon ion source (AHIS-II) equipped with a novel triode extraction system has been designed and developed at the Helicon Plasma Laboratory of Amirkabir University of Technology for material-processing applications. An experimental study was conducted to investigate the effects of two new types of plasma electrodes on ion beam characteristics. In particular, the Khoshhal electrode as a new improved plasma electrode and the optimized Pierce plasma electrode were both compared in inductively coupled plasma in the m = +1, −1 helicon plasma modes of operation. In this work, the AHIS-II device, with its ability to work continuously, was able to extract a ∼1 mA argon ion beam using a triode extraction system equipped with a Khoshhal plasma electrode at a 20 kV extraction voltage in the m = +1 helicon mode of operation. As part of this work, the R parameter, the ratio of the voltage
applied to the plasma and acceleration electrodes in triode extraction systems was introduced, and its effects on ion beam characteristics including beam emittance, diameter, and current were studied. In this study, beam optical characteristics including beam emittance, diameter, current, and profile were calculated and measured by the IBSimu ion optical code. The analysis of the argon ion beam highlights that the ion beam characteristics can be affected not only by the plasma electrode geometry design, R parameter, and extraction voltage associated with the extraction process, but also by the plasma source’s operational parameters, such as the RF power delivered to the half-helix antenna and the gas flow rate.
Microscopic Coulomb interaction in transition-metal dichalcogenides
Authors: Neuhaus J , Liebscher S C , Meckbach L , Stroucken T , Koch S W 
Published: September 2020

Abstract
The quasi-two dimensional Coulomb interaction potential in transition metal dichalcogenides is determined using the Kohn–Sham wave functions obtained from ab initio calculations. An effective form factor is derived that accounts for the finite extension of the wave functions in the direction perpendicular to the material layer. The resulting Coulomb matrix elements are used in microscopic calculations based on the Dirac Bloch equations yielding an efficient method to calculate the band gap and the opto-electronic material properties in different environments and under various excitation conditions.
Autonomous topological time crystals and knotty molecular motors
Authors: Dai Jin , Peng Xubiao , Niemi Antti J 
Published: September 2020

Abstract
We show that topology is a very effective tool, to construct classical Hamiltonian time crystals. For this we numerically analyze a general class of time crystalline Hamiltonians that are designed to model the dynamics of molecular closed strings. We demonstrate how the time crystalline qualities of a closed string are greatly enhanced when the string becomes knotted. The Hamiltonians that we investigate include a generalized Kratky–Porod wormlike chain model in combination with long range Coulomb and Lennard–Jones interactions. Such energy functions are commonplace in coarse grained molecular modeling. Thus we expect that physical realizations of Hamiltonian time crystals can be constructed in terms of knotted ring molecules.
Multiple dynamic regimes in a coarsening foam
Authors: Giavazzi Fabio , Trappe Veronique , Cerbino Roberto 
Published: September 2020

Abstract
Intermittent dynamics driven by internal stress imbalances in disordered systems is a fascinating yet poorly understood phenomenon. Here, we study it for a coarsening foam. By exploiting differential dynamic microscopy and particle tracking we determine the dynamical characteristics of the foam at different ages in reciprocal and direct space, respectively. At all wavevectors q investigated, the intermediate scattering function exhibits a compressed exponential decay. However, the access to unprecedentedly small values of q highlights the existence of two distinct regimes for the q-dependence of the foam relaxation rate Γ(q). At high q, Γ(q) ∼ q consistent with directionally-persistent and intermittent bubble displacements. At low q, we find the surprising scaling Γ(q) ∼ q

δ
, with δ = 1.6 ± 0.2. The analysis of the bubble displacement distribution in real space reveals the existence of a displacement cut-off of the order of the bubble diameter. Introducing such cut-off length in an existing model, describing stress-driven dynamics in disordered systems, fully accounts for the observed behavior in direct and reciprocal space.
Electric field-induced chiral d
+
id superconductivity in AA-stacked bilayer graphene: a quantum Monte Carlo study
Authors: Fang Shi-Chao , Zheng Xiao-Jun , Lin Hai-Qing , Huang Zhong-Bing 
Published: September 2020

Abstract
Using the constrained-path quantum Monte Carlo method, we systematically study the half-filled Hubbard model on AA-stacked honeycomb lattice. Our simulations demonstrate that a dominant chiral d + id wave superconductivity can be induced by a perpendicular electric field. At a fixed electric field, the effective pairing interaction of chiral d + id superconductivity exhibits an increasing behavior with increasing the on-site Coulomb interaction. We attribute the electric field-induced d + id superconductivity to an increased density of states near the Fermi energy and robust antiferromagnetic spin correlation upon turning on electric field. Our results strongly suggest that the AA-stacked graphene system is a good candidate for chiral d + id superconductor.
Anisotropic thermal conductivity of the nanoparticles embedded GaSb thin film semiconductor
Authors: Koh Yee Rui , Lu Hong , Gossard Arthur C , Shakouri Ali 
Published: September 2020

Abstract
The prior theoretical model shows that GaSb is one of the few non-alloy semiconductors showing phonons ballistic effect in the thermal conductivity. However, no previous literature had been reported on the experimental measurements on the quasi-ballistic thermal transport of the GaSb thin film. In this paper, we employed the time-domain thermoreflectance (TDTR) to study the thermal transport of nanoparticles embedded GaSb thin film. Our measurements results provide first experimental evidence to verify the quasi-ballistic effect in the thermal transport of the GaSb thin film. The apparent cross-plane thermal conductivity of pure GaSb sample drops ∼15% when the pump laser modulation frequency is increased from 0.8 MHz to 10 MHz at room temperature. To further understand the thermal transport mechanism, Tempered Lévy analysis is employed to study the quasi-ballistic effect of the GaSb thin film. The model shows that GaSb thin film thermal transport has a superdiffusion exponent,

α

= 1.51 ± 0.23 and Lévy-Fourier transition length, r
LF = 0.19 ± 0.13 µm. Both obtained values via Tempered Lévy indicates the quasi-ballistic transport phenomena in GaSb thin film. However, this frequency dependence of the cross-plane thermal conductivity will disappear in the presence of the 3%–20% ErSb nanoparticles. Another thermal transport mechanism, i.e. anisotropic thermal transport, can be observed in GaSb thin film. The ratio of in- to cross-plane thermal conductivity varies from ∼0.2 to ∼0.7 in the 0%–20% ErSb nanoparticles volume concentrations. Detailed temperature dependence of the in-plane thermal conductivity of ErSb:GaSb samples with 0%–20% are also included in the paper for the understanding of the scattering mechanism in the thin film thermal transport. With enhanced understanding of the quasi-ballistic and anisotropic thin film thermal transport, our results might improve the thermal management efficiency of the GaSb devices.
Investigation of underwater quantum channels in a 30 meter flume tank using structured photons
Authors: Hufnagel Felix , Sit Alicia , Bouchard Frédéric , Zhang Yingwen , England Duncan , Heshami Khabat , Sussman Benjamin J , Karimi Ebrahim 
Published: September 2020

Abstract
Underwater quantum communication has recently been explored using polarization and orbital angular momentum (OAM). Here, we show that spatially structured modes, e.g., a coherent superposition of beams carrying both polarization and OAM, can also be used for underwater quantum cryptography. We also use the polarization degree of freedom to investigate the impact of the channel length on key rates for quantum communication applications. The underwater channel proves to be a difficult environment for establishing quantum communication as underwater optical turbulence results in significant beam wandering and distortions. However, the errors associated to the turbulence do not result in error rates above the threshold for establishing a positive key in a quantum communication link with both the polarization and spatially structured photons. The impact of the underwater channel on the spatially structured modes is also investigated at different distances using polarization tomography.
Sub-wavelength spin excitations in ultracold gases created by stimulated Raman transitions
Authors: Ilin Yigal , Tsesses Shai , Bartal Guy , Sagi Yoav 
Published: September 2020

Abstract
Raman transitions are used in quantum simulations with ultracold atoms for cooling, spectroscopy and creation of artificial gauge fields. Spatial shaping of the Raman fields allows local control of the effective Rabi frequency, which can be mapped to the atomic spin. Evanescent Raman fields are of special interest as they can provide a new degree of control emanating from their rapidly decaying profile and for their ability to generate features below the diffraction limit. This opens the door to the formation of sub-wavelength spin textures. In this work, we present a theoretical and numerical study of Raman Rabi frequency in the presence of evanescent driving fields. We show how spin textures can be created by spatially varying driving fields and demonstrate a skyrmionium lattice—a periodic array of topological spin excitations, each of which is composed of two skyrmions with opposite topological charges. Our results pave the way to quantum simulation of spin excitation dynamics in magnetic materials, especially of itinerant spin models.
Geometrical confinement effects on fundamental thermal properties of rutile and anatase TiO2 cylindrical and tubular nanostructures
Authors: Feddi K , Kria M , El-Yadri M , Mbognou F C Fobasso , Long G , Tiutiunnyk A , Pérez L M , Laroze D , Feddi E 
Published: September 2020

Abstract
In this work, we investigated the influence of the geometrical confinement effects on the fundamental thermal properties of rutile and anatase TiO2 for both cylindrical nanostructures (CNSs) and nanotubular structures (NTSs), respectively. Calculations of energy levels are developed in the framework of effective mass approximation by generalizing the resolution of Schrödinger equation in a truncated cylinder. The energy spectrum is then used in the determination of thermodynamic properties by using the Boltzmann-Gibbs distribution. Numerical computations done for both rutile and anatase TiO2 nanomaterials reveal a strong localization of the electron orbitals along to the lateral surface for all the studied are CNS and NTS. The average energy, heat capacity, entropy, and Helmholtz free energy calculated for different thicknesses for NTS and different cross-sections of CNS. Our numerical investigation shows that all thermodynamic properties depend on the temperature, the cross-section for the CNS, and the shell thickness for the NTS. We demonstrated that for low thickness, the heat capacity shows a Schottky-like anomaly at low temperatures. We also show that the Rutile structure is more stable than anatase. We hope that the thermodynamic properties concluded from this study can be considered as useful information for understanding the thermodynamic properties of TiO2 nanofibers.
Finite Element analysis on the performance of strengthening Concrete Structures confined using Natural and Artificial fibers
Authors: Navaneeth Krishnan K , Hari Rahesh , Mini Dr K M 
Published: September 2020

Abstract
In India, there is a drastic increase in the rehabilitation and retrofitting of existing structures compared to demolition. In the current paper, the performance of basalt fiber as a strengthening material in concrete structures for retrofitting application is explored using finite element method rather than the costly experimental method. The model is developed using Jhonson cook’s model and is compared with the experimental results for its validation. JC model incorporated with master-slave interaction between concrete-binder and fabric -binder have been modelled as shell elements which replicate the actual scenario of tension or compression only. Analytical models have been emerged as a powerful solution for experimenting stress-strain analysis in composites.
Influence of geometric and operating parameters on the flow behavior of the helical capillary tube
Authors: Jadhav P L , Agrawal N A 
Published: September 2020

Abstract
This paper reveals numerical study on an adiabatic helical capillary tube employing homogenous and unchoked flow conditions for a CO2 refrigerant. The numerical model is based on the basic principles of conservation of mass, momentum, and energy. A result of the present model is validated with previously published test results. Thermodynamic and transport properties of CO2 refrigerant are obtained from property code CO2PROP which is developed by employing an iterative procedure of derivatives of Helmholtz free energy function. The influence of various geometric parameters like tube diameter, roughness, and coil diameter on the mass flow rate of the capillary tube has been evaluated. The mass flow of the helical capillary tube largely depends on the internal diameter. While the very minor change in mass is observed with change surface roughness. Influence of various operating factors like gas cooler pressure, temperature and evaporator temperature evaluated. A significant change in mass is observed with the change in gas cooler temperature, comparatively less effect is observed with evaporator temperature. For optimum performance of the transcritical CO2 cycle, selection of proper gas cooler temperature, gas cooler pressure is a key factor. This study may be useful for the design of helical capillary tube for CO2.
Fabrication and Characterization of 20 MHz Quarter Wave Helical Resonator
Authors: Nandi Joydip , Das Parnika , Sikdar A K , Reza Ashif , Misra Anuraag 
Published: September 2020

Abstract
To increase the signal to noise ratio, helical resonator is generally employed in between trap signal pick up electrode and Low noise amplifier having high input impedance. Based on available literature and simulation study, a 20MHz Helical resonator was designed and fabricated. The measured resonant frequencyand quality factor of the fabricated resonator is 19.67 MHz and 1030 respectively. Simulation results are found in good agreement with the fabricated resonator parameter. Effect of material’s conductivity on the quality factor of the resonator is also studied.
Evaluation of Cretaceous deposits of the Yamal Peninsula for their hydrocarbon potential based on the water-gas equilibria modeling results
Authors: Novikov D. A. 
Published: September 2020

Abstract
Results of the evaluation of petroleum-bearing potential of Yamal’s Cretaceous deposits based on the study of water-gas equilibria are presented. It has been established that the “water-gas” system within them has a complex and unequal pattern. Hydrocarbon accumulations serve as “relics” of antecedent hydrogeological epochs, with groundwater being the most mobile component of this system. The sediments composition is therefore subjected to a slow directional change aimed at establishing an equilibrium, which subsequently results in a qualitatively new state of their geochemical framework. Most of the studied area is characterized by very favorable conditions for persistent preservation of oil and gas accumulations. In northern and central regions of Yamal, there is a slight shift in the water – gas system phase equilibrium, suggesting a potential for discovery of new oil/gas pools and significant hydrocarbon reserves within them. The analysis confirmed the presence of earlier discovered hydrocarbon pools within the studied fields and enabled prediction of new thirteen accumulations. The hydrogeochemical analysis and the water-gas equilibria modeling results have shown that the prospects are significantly lower for new discoveries in SW Yamal.
Investigation of the gas-dynamic processes in the operation of an explosion-reactive complex
Authors: Solov’ev V O , Shvedov I M 
Published: September 2020

Abstract
To conduct drilling and blasting operations in difficult climatic and geological conditions at mining enterprises, it is promising to use explosion-reactive complexes (ERC). Having a clear advantage, these devices have a number of disadvantages, mainly due to the gas-dynamic instability of the process of their functioning. A non-stationary gas-dynamic model of the development of such processes at different stages of ERC operation was developed and analyzed. The analysis was performed by methods of numerical mathematical modelling. The simulation results allowed the authors to further justify the rational parameters of the installation and its individual components, which significantly increased its efficiency.
Pragmatic studies on automated properties of High Efficiency Concrete
Authors: Bhavani Chowdary T , Teja J 
Published: September 2020

Abstract
The term high efficiency concrete is similar to high performance (HPC) is vividly used in the concrete industry since it has definite rheological properties in comparison with traditional concrete. Current research specifies the outcome of silica fume (SF) inclusion to M60 grade concrete by cumulative percentage replacements of SF with respect to cement, from 0-15 varying 5 and steel fiber of 1 percent is added by weight of cementitious binder. A super plasticizer of 1% is added to enhance workability of concrete. Water-binder ratio (w/b) is maintained at a ratio of 0.33. Mechanical properties of HPC are studied and results were tabulated.
Modelling the Shear Flow Behaviour of Cement Paste Using Machine Learning –XGBoost
Authors: Sathyan Dhanya , Govind D , Rajesh C B , Gopikrishnan K , Aswath Kannan G , Mahadevan Jayanth 
Published: September 2020

Abstract
In recent years machine learning is considered as a highly effective and widely used tool to predict the behaviour of complex and heterogeneous problems. In this paper, the behaviour of superplasticised cement paste is assessed by XGBoost, which is accepted to accomplish the state-of-the-art results on many machine learning challenges. The data required for the development of model is formulated experimentally by conducting rheological tests on cement pastes using a temperature controlled Coaxial Cylinder Viscometer. Various parameters like amount of cement, superplasticiser, water and test temperature are taken as input parameters and the behaviour is assessed by taking rheological characterises like yield stress and plastic viscosity as output parameters. Out of the 252 data formulated experimentally 85 % are used for training and the remaining is for testing the efficacy of the network. From the results it is observed that the model developed using XGBoost is a promising tool for the solution of highly complex and heterogeneous civil engineering problems, which otherwise is highly tedious and time consuming in nature.
MXene and MBene as efficient catalysts for energy conversion: roles of surface, edge and interface
Authors: Zhou Si , Yang Xiaowei , Pei Wei , Jiang Zhou , Zhao Jijun 
Published: September 2020

Abstract
MXenes and MBenes emerge from a large family of two-dimensional (2D) transition metal carbides, nitrides, carbonitrides, and borides and have drawn tremendous attention in recent years. They possess diverse elemental compositions, surface terminations and geometrical structures, and exhibit many fascinating physical and chemical properties. Specifically, these 2D compounds hold great promise for renewable energy applications owing to their superior electrical conductivity, high hydrophility, rich surface chemistry, and outstanding stability. In this perspective, we present a brief overview about the catalytic properties of MXenes, MBenes and MXene based heterostructures for typical electrochemical reactions. The roles of surface, edge and interface of these 2D nanostructures in energy conversion are highlighted from a theoretical point of view. Challenges and outlooks for future research are also outlined.
Influence of salt addition on polymer-free electrospinning of cyclodextrin nanofibers
Authors: Topuz Fuat , Celebioglu Asli , Aytac Zeynep , Uyar Tamer 
Published: September 2020

Abstract
Solution conductivity is one of the critical parameters affecting the electrospinning of polymer solutions as the jet formation is directly related to the movement of an electrically charged polymer solution to a grounded target. Hence, the solution conductivity has been studied for the electrospinning of various polymeric systems, but not yet for the electrospinning of polymer-free systems. In this regard, this study investigates the influence of solution conductivity on the electrospinning of CD molecules (i.e., hydroxypropyl (HP) modified β and γ -CDs) at various concentrations in the presence of quaternary ammonium salt (i.e., tetraethylammonium bromide, TEAB) from aqueous solutions. The addition of TEAB significantly boosted the conductivity of the CD solutions. It could lead to smaller particles at low CD concentrations because of electrohydrodynamic spraying, while the transformation from beaded-fibers to bead-free fibers was observed with an increase in the CD concentration. The salt addition decreased the fiber diameter and resulted in thinner nanofibers. Likewise, the incorporation of NaCl –used as an alternative to TEAB- caused thinning of the fibers due to enhanced solution conductivity. On the other hand, at higher salt contents, the fiber morphology was worsened for both CDs, leadings to beads on the fibers. Overall, this paper, for the first time, investigates the effect of solution conductivity of the electrospinning of a polymer-free system (i.e., CD), and the experimental findings show that increasing the solution conductivity with salt addition causes significant changes on the electrospinnability and fiber properties.