Showing papers in "AIP Advances in 2019"
TL;DR: In this article, a similarity technic is applied to alter governing energy and momentum equations into non-linear ordinary differential ones that contain the convenient boundary conditions and used the Duan-Rach Approach (DRA) to solve them.
Abstract: In this paper, the researchers explore heat transfer and magneto-hydrodynamic flow of hybrid nanofluid in a rotating system among two surfaces. The upper and lower plates of the system are assumed penetrable and stretchable, respectively. The thermal radiation and Joule heating impacts are considered. A similarity technic is applied to alter governing energy and momentum equations into non-linear ordinary differential ones that contain the convenient boundary conditions and used the Duan-Rach Approach (DRA) to solve them. Influences of assorted parameters including rotation parameter, suction/blowing parameter, radiation parameter, Reynolds number, hybrid nanofluid volume fraction, and magnetic parameter on temperature and velocity profiles are examined. Also, a correlation for the Nusselt number has been developed in terms of the acting parameters of the present study. The outcomes indicate that Nusselt number acts as an ascending function of injection and radiation parameters, as well as volume fraction of nanofluid.
190 citations
TL;DR: In this paper, a modified auxiliary equation method was applied to describe (1 + 1)-dimensional dispersive long wave in two horizontal directions on shallow waters, which is one of the fractional nonlinear partial differential equations.
Abstract: In this paper, we examine a modified auxiliary equation method. We applied this novel method on Wu-Zhang system. This model used to describe (1 + 1)-dimensional dispersive long wave in two horizontal directions on shallow waters. This model is one of the fractional nonlinear partial differential equations. We used conformable derivatives properties to convert nonlinear fractional partial differential equation into the ordinary differential equation with integer order. We obtained many different kinds of solutions such as kink and anti-kink, dark, bright, shock, singular, periodic solitary wave.
104 citations
TL;DR: This paper proposes a data-driven nonlinear low-dimensional representation method for unsteady flow fields that preserves its spatial structure and uses a convolutional autoencoder, which is a deep learning technique.
Abstract: A method capable of comparing and analyzing the spatio-temporal structures of unsteady flow fields has not yet been established. Temporal analyses of unsteady flow fields are often done after the data of the fields are reduced to low-dimensional quantities such as forces acting on objects. Such an approach is disadvantageous as information about the flow field is lost. There are several data-driven low-dimensional representation methods that preserve the information of spatial structure; however, their use is limited due to their linearity. In this paper, we propose a method for analyzing the time series data of unsteady flow fields. We firstly propose a data-driven nonlinear low-dimensional representation method for unsteady flow fields that preserves its spatial structure; this method uses a convolutional autoencoder, which is a deep learning technique. In our proposed method, the spatio-temporal structure can be represented as a trajectory in a low-dimensional space using the visualization technique originally proposed for dynamic networks. We applied the proposed method to unsteady flows around a two-dimensional airfoil and demonstrated that it could briefly represents the changes in the spatial structure of the unsteady flow field over time. This method was demonstrated to also be able to visualize changes in the quasi-periodic state of the flow when the angle of attack of the airfoil was changed. Furthermore, we demonstrated that this method is able to compare flow fields that are constructed using different conditions such as different Reynolds numbers and angles of attack.
70 citations
TL;DR: In this article, the Rydberg atoms were used as an RF mixer for weak E-field detection well below the AT regime with frequency discrimination better than 1 Hz resolution, where the detection was performed on a vapor cell filled with cesium atoms.
Abstract: Rydberg atoms have been used for measuring radio-frequency (RF) electric (E)-fields due to their strong dipole moments over the frequency range of 500 MHz-1 THz. For this, electromagnetically induced transparency (EIT) within the Autler-Townes (AT) regime is used such that the detected E-field is proportional to AT splitting. However, for weak E-fields AT peak separation becomes unresolvable thus limiting the minimum detectable E-field. Here, we demonstrate using the Rydberg atoms as an RF mixer for weak E-field detection well below the AT regime with frequency discrimination better than 1 Hz resolution. A heterodyne detection scenario with two E-fields incident on a vapor cell filled with cesium atoms is used. One E-field at 19.626000 GHz drives the 34D5/2 → 35P3/2 Rydberg transition and acts as a local oscillator (LO) and a second signal E-field (Sig) of interest is at 19.626090 GHz. In the presence of the LO, the Rydberg atoms naturally down convert the Sig field to a 90 kHz intermediate frequency (IF) signal. This IF signal manifests as an oscillation in the probe laser intensity through the Rydberg vapor and is easily detected with a photodiode and lock-in amplifier. In the configuration used here, E-field strength down to ≈ 46 μV/m ± 2 μV/m were detected with a sensitivity of ≈ 79 μVm−1Hz−1/2. Furthermore, neighboring fields 0.1 Hz away and equal in strength to Sig could be discriminated without any leakage into the lock-in signal. For signals 1 Hz away and as high as +60 dB above Sig, leakage into the lock-in signal could be kept below -3 dB.
67 citations
TL;DR: In this article, the Nusselt number and the Skin fraction coefficient of single and multi-wall carbon nanotubes are compared with the same Nussellt number for single and multilayer nanotube.
Abstract: The main objective of this article is to study the inventive conception of the electrical Magneto hydrodynamics (MHD) rotational flow of Single and Multi-Walled Carbon nanotubes (SWCNTs/MWCNTs) base on the fluids (water, engine oil, ethylene glycol and kerosene oil). The thermal radiation impact is taken to be varying the purpose, to see the concentration as well as the temperature modifications between the nanofluid and the surfaces. Kerosene oil is taken as based nanofluids because of its unique attention due to their advanced thermal conductivities, exclusive features and applications. The fluid flow is assumed in steady state. The basic Navier Stocks equations have been transformed through similarity variables in the form of nonlinear differential equations. The solution of the problem has been obtained through Homotopy Analysis Method (HAM). Results obtained for single and multi-wall carbon nanotubes are compared. Plots have been presented in order to examine how the velocities and temperature profile get affected by various flow parameters. The numerical outputs of the physical properties are shown trough tables. The impact of Skin fraction coefficient and Nusselt number are shown in tables.The main objective of this article is to study the inventive conception of the electrical Magneto hydrodynamics (MHD) rotational flow of Single and Multi-Walled Carbon nanotubes (SWCNTs/MWCNTs) base on the fluids (water, engine oil, ethylene glycol and kerosene oil). The thermal radiation impact is taken to be varying the purpose, to see the concentration as well as the temperature modifications between the nanofluid and the surfaces. Kerosene oil is taken as based nanofluids because of its unique attention due to their advanced thermal conductivities, exclusive features and applications. The fluid flow is assumed in steady state. The basic Navier Stocks equations have been transformed through similarity variables in the form of nonlinear differential equations. The solution of the problem has been obtained through Homotopy Analysis Method (HAM). Results obtained for single and multi-wall carbon nanotubes are compared. Plots have been presented in order to examine how the velocities and temperature profil...
66 citations
TL;DR: In this paper, the authors demonstrate deterministic generation and switching of dissipative Kerr solitons (DKSs) in a thermally controlled micro-ring resonator based on high-index doped silica glass platform.
Abstract: In this paper, we first experimentally demonstrate deterministic generation and switching of dissipative Kerr solitons (DKSs) in a thermally controlled micro-ring resonator based on high-index doped silica glass platform. In our scheme, an auxiliary laser is introduced to timely balance the intra-cavity heat fluctuation. By decreasing the operation temperature through a thermo-electric cooler, primary-, chaotic-comb and soliton crystal are firstly generated, then increasing the temperature, DKSs switching and single soliton are robustly accessed, which is independent of the tuning speed. During the switching process, varieties of DKSs are identified by tens of the characteristic “soliton-steps”. Besides, by simply changing the operation temperature under which the DKSs are formed, the center wavelength of dispersive waves could be tuned in a broadband range. When the micro-ring resonator operating at temperature larger than 63.5 °C, avoided mode-crossing free soliton can be obtained. Our results are favorable for study of on-chip soliton dynamics and practical nonlinear applications.
65 citations
TL;DR: Comparisons of different hysteresis models reveal that rate-dependent differential-based modeling is the future research focus and feedforward-feedback control and feedback control are the emphasis in the future.
Abstract: Piezoelectric actuators are gradually playing an important role in precision positioning applications due to their extremely fine resolution, fast responses, and large actuating forces. However, the existence of hysteresis behaviors makes a big influence on their positioning accuracies. To get high positioning accuracies, hysteresis modeling and control of piezoelectric actuators are meaningful and necessary. This paper reviews different models and control approaches of piezoelectric actuators. Novel categories of both hysteresis models and control approaches are presented. Furthermore, comparisons of different hysteresis models reveal that rate-dependent differential-based modeling is the future research focus. Comparisons of control approaches of piezoelectric actuators are presented and feedforward-feedback control and feedback control are the emphasis in the future.
64 citations
TL;DR: In this article, a sol-gel synthesis of Zn doped spinel Co1-xZnxFe2O4 (where x = 0.0, 0.1,0.2, and 0.3) was reported.
Abstract: The finely controlled nanostructured cubic spinel ferrites pave the way to synthesize nanomaterials with specific properties for particular applications. In this paper, we report sol-gel synthesis of Zn doped spinel Co1-xZnxFe2O4 (where x= 0.0, 0.1, 0.2, and 0.3) ferrite nanoparticles. X-ray diffraction confirms the single phase cubic structure of nano ferrites with average particle size estimated between 55.38 to 32.87 nm and validated by Transmission electron microscopy (TEM) results (±1). The lattice parameter was found to increase with increasing Zn doping concentration. The samples exhibit normal dielectric behaviour of Maxwell-Wagner type of interfacial polarization that decreases with increasing frequency of the applied field. Temperature-dependent magnetic properties were investigated with the aid of physical property system. The hysteresis measurements of the samples show clearly enhancement in magnetic parameters as the temperature goes down to 20 K. Tuning of magnetic properties has been witnessed as a function of doping and temperature under the influence of externally applied magnetic field, has been discussed in this paper.
61 citations
TL;DR: In this article, an analysis of the variable thermophysical features of the three-dimensional flow of a non-Newtonian yield manifesting liquid with heat and mass transport in the presence of gyrotactic microorganisms over a nonlinear stretched surface is inspected.
Abstract: Mathematical analysis of the variable thermophysical features of the three-dimensional flow of a non-Newtonian yield manifesting liquid with heat and mass transport in the presence of gyrotactic microorganisms over a nonlinear stretched surface is inspected in this exploration. The phenomenon of heat is presented in view of temperature-dependent thermal conductivity by engaging the traditional heat conduction law, whereas transport of mass is expressed by capitalizing Fick’s law with temperature dependent mass diffusion. The Buongiorno model is presented for capturing the involvement of Brownian motion and thermophoresis inspirations. Additionally, the chemical reaction is considered in the mass transport expression. Boundary layer theory is applied to develop the physical problem in the form of partial differential equations. Appropriate transformation is utilized to convert the developed problem into a dimensionless system of coupled nonlinear ordinary differential equations. The transformed system is then handled analytically. The convergence analysis of the proposed scheme is presented through a table, which confirms the reliability of the suggested procedure. Moreover, the validity of the present solution and suggested scheme is presented and the limiting case of presented findings is in excellent agreement with the available literature. The computed solution of the physical variables against the influential parameters is presented through graphs. It is worth mentioning that mounting values of the fluid parameter and magnetic parameter retard the fluid flow.
55 citations
TL;DR: In this paper, the authors explore the possibility of using fluorine doped tin oxide (FTO) as an alternative to ITO for the bottom electrode of organic solar cells particularly on semi-transparent cells.
Abstract: Indium tin oxide (ITO) is commonly used as the transparent bottom electrode for organic solar cells. However, it is known that the cost of the ITO is quite high due to the indium element, and in some studies ITO coated glass substrate is found to be the most expensive component of device fabrication. Moreover, indium migration from ITO can cause stability issues in organic solar cells. Nevertheless, the use of ITO as the bottom electrode is still dominating in the field. Here, we explore the possibility of using fluorine doped tin oxide (FTO) as an alternative to ITO for the bottom electrode of organic solar cells particularly on semi-transparent cells. We present side-by-side comparisons on their optical, morphological and device properties and suggest that FTO could be more suitable than ITO as the bottom electrode for glass substrate based organic photovoltaic devices.
55 citations
TL;DR: In this article, the origins and recent advances in this rapidly developing field of dielectric nanophotonics, paying special attention to the main significant contributions we have done since its startup to boost its progress.
Abstract: Nanoparticles made of High Refractive Index dielectric materials have been proposed as an alternative to metals driven by their low-losses and magnetic response. The coherent effects between the electric and magnetic resonances are responsible for their exceptional directionality properties that make them attractive in applications where enhancing light-matter interaction and controlling the radiation direction is extremely relevant. These nanoparticles, when used as unit-cells of more complex systems, such as metasurfaces, result to be essential in the design of novel optical devices. Their low-losses, strong confinement of electromagnetic energy and the outstanding scattering efficiencies show these nanoantennas as promising candidates for Surface Enhanced Spectroscopies, non-linear phenomena or sensing. Here, we describe and discuss the origins and recent advances in this rapidly developing field of dielectric nanophotonics, paying special attention to the main significant contributions we have done since its startup to boost its progress. In particular, light directivity, steering and switching of light, spectroscopy, sensing and non-linear phenomena, third harmonic generation are some of the applications that motivated this brief overview.
TL;DR: In this paper, the Darcy Forchheimer 2D thin film fluid of nanoliquid is analyzed and the transformation of partial differential set of equations into strong ordinary differential frame is formed through appropriate variables.
Abstract: This article analyzes the Darcy Forchheimer 2D thin film fluid of nanoliquid. Flow of nanoliquid is made due to a flat unsteady stretchable sheet. In nanoliquids, nanomaterial is in form of CNTs (carbon nanotubes). Also, in present analysis, single walled carbon nanotubes (SWCNTs) are accounted as nanoparticles. The classical liquid ‘water’ is treated as based liquid. The flow in permeable region is characterized by Darcy–Forchheimer relation. Heat transport phenomena are studied from convective point of view. The transformation of partial differential set of equations into strong ordinary differential frame is formed through appropriate variables. Homotopy Analysis Method (HAM) scheme is executed for solving the simplified set of equations. In addition, a numerical analysis (ND-Solve) is utilized for the convergence of the applied technique. The influence of some flow model quantities like Pr (Prandtl number), λ (unsteadiness factor), k (porous medium factor), F (Darcy-porous medium factor) on liquid velocity and thermal field are scrutinized and studied through sketches. Certain physical factors like f″(0) (friction factor coefficient) and −θ′(0) (rate of heat transport) are first derived and then presented through tables.
TL;DR: This work successfully applies Deep Reinforcement Learning (DRL) for the control of the one-dimensional depth-integrated falling liquid film, and introduces for the first time translational invariance in the architecture of the DRL agent and exploits locality of the control problem to define a dense reward function.
Abstract: Instabilities arise in a number of flow configurations. One such manifestation is the development of interfacial waves in multiphase flows, such as those observed in the falling liquid film problem. Controlling the development of such instabilities is a problem of both academic interest and industrial interest. However, this has proven challenging in most cases due to the strong nonlinearity and high dimensionality of the underlying equations. In the present work, we successfully apply Deep Reinforcement Learning (DRL) for the control of the one-dimensional depth-integrated falling liquid film. In addition, we introduce for the first time translational invariance in the architecture of the DRL agent, and we exploit locality of the control problem to define a dense reward function. This allows us to both speed up learning considerably and easily control an arbitrary large number of jets and overcome the curse of dimensionality on the control output size that would take place using a naive approach. This illustrates the importance of the architecture of the agent for successful DRL control, and we believe this will be an important element in the effective application of DRL to large two-dimensional or three-dimensional systems featuring translational, axisymmetric, or other invariance.
TL;DR: In this article, the effect of different types of ice on the ice adhesion strength was investigated and the results indicate that the ice strength inversely correlates with the density of ice.
Abstract: To lower the ice adhesion strength is the most efficient technique for passive ice removal for several applications. In this paper, the effect of different types of ice on the ice adhesion strength was investigated. The ice types precipitation ice, in-cloud ice and bulk water ice on the same aluminum substrate and under similar environmental conditions were investigated. The ice adhesion strength was measured with a centrifugal adhesion test and varied from 0.78 ± 0.10 MPa for precipitation ice, 0.53 ± 0.12 MPa for in-cloud ice to 0.28 ± 0.08 MPa for bulk water ice. The results indicate that the ice adhesion strength inversely correlates with the density of ice. The results inspire a new strategy in icephobic surface development, specifically tailored to the relevant ice type.
TL;DR: In this paper, a numerical model of a typical multistage centrifugal pump model was constructed and the flow investigated systematically under different operating conditions, and changes in amplitude, frequency, and phase of pressure fluctuation in the impellers, diffusers, and pump cavities were observed and analyzed in both time-domain and frequency-domain.
Abstract: Multistage centrifugal pumps can provide high-pressure fluid flow, and is widely used in various engineering applications. However, the pressure fluctuation in the pumps strongly affects the flow and pressure stability. To gain further insight into the pressure fluctuation of multistage centrifugal pumps, a numerical model of a typical multistage centrifugal pump model was constructed and the flow investigated systematically under different operating conditions. Changes in amplitude, frequency, and phase of pressure fluctuation in the impellers, diffusers, and pump cavities were observed and analyzed in both time-domain and frequency-domain. The pressure fluctuations of the fluid in the impeller were found to originate from the inlet side of the outward diffuser, whereas that in the diffuser arose from the outlet side of the impeller blade. In contrast, the pressure fluctuations in the pump cavity were initiated from the outlet side of the impeller blade and the interstage leakage of fluid. This study also conclude that the pressure fluctuations are essentially a wave with identifiable amplitude, frequency, and phase.
TL;DR: In this article, the structural, electronic, mechanical, and optical properties of lead and lead-free metal halide cubic perovskites CsPbBr3 and CsGeBr3 were studied using the first-principle density functional theory.
Abstract: Metal halide perovskites have become more popular for applications in solar cells and optoelectronic devices. In this study, the structural, electronic, mechanical, and optical properties of lead and lead-free metal halide cubic perovskites CsPbBr3 and CsGeBr3 and their Ni-doped structures have been studied using the first-principle density functional theory. Ni-doped CsGeBr3 shows enhanced absorbance both in the visible and the ultraviolet region. The absorption edge of Ni-doped CsBBr3 (B = Pb, Ge) shifts toward the lower energy region compared to their undoped structures. Undoped and Ni-doped lead and lead-free halides are found to have a direct bandgap, mechanical stability, and ductility. A combined analysis of the electronic, mechanical, and optical properties of these compounds suggests that lead-free perovskite CsGe0.875Ni0.125Br3 is a more suitable candidate for solar cells and optoelectronic applications.
TL;DR: In this article, the authors demonstrate the theoretical study on the electronic band structures of PtS2 with different thickness by using density functional theory (DFT), as well as experimental realization of large-area synthesis of few-layer PtS 2 film by direct sulfurization of pre-deposited Pt.
Abstract: PtS2, a group-10 transition metal dichalcogenide, has prominent layer-depended band structure, and can enable extremely high phonon-limited mobility at room temperature. Here, we demonstrate the theoretical study on the electronic band structures of PtS2 with different thickness by using density functional theory (DFT), as well as experimental realization of large-area synthesis of few-layer PtS2 film by direct sulfurization of pre-deposited Pt. The synthetic process suggested that the reaction pressure is a key factor in the formation of high-quality PtS2 semiconducting films. Characterizations with atomic force microscopy (AFM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) have indicated that good film stoichiometry and uniformity have been achieved. Furthermore, field-effect transistor (FET) arrays were fabricated based on the large-scale PtS2 film, exhibiting well-uniform electrical performance with p-type transport behavior. These results can open up an attractive approach to promote the large-scale applications of PtS2 in advanced nanoelectronics and optoelectronics devices and systems.
TL;DR: In this paper, the authors inspect the flow of magnetohydrodynamic (MHD) stratified micropolar bioconvective fluid containing nanoparticles and gyrotactic microorganism.
Abstract: The forthright purpose of this communication is to inspect the flow of magnetohydrodynamic (MHD) stratified micropolar bioconvective fluid containing nanoparticles and gyrotactic microorganism. The phenomenon of thermal radiation and Joule heating has also been incorporated. In order to stabilize the suspended nanoparticles, bioconvection which is established by the combined effects of magnetic field and buoyancy force is implemented. A system of PDEs is converted into the ODEs by invoking the appropriate similarity transformation and the transformed equations are then solved by the well known shooting technique. The interesting aspects of sundry parameters on the velocity, the angular velocities, the temperature, concentration and the motile microorganism density are examined and sketched. The skin friction and the couple stress coefficients, the heat and mass transfer rates and the local density number of the motile microorganism have been numerically computed and discussed. Our analysis depicts that the temperature, concentration and motile microorganism density depreciate for the increment in the material parameter. An enhancement in the buoyancy ratio parameter results an enhancement in the energy and the motile microorganism density profile whereas the velocity profile is reduced.
TL;DR: In this article, the authors studied the laser interaction with bulk target and particle products in detail, including mechanism process, target morphology and nanoparticle products, and found that the first bubble oscillation has the greatest impact on the nanomaterial synthesis.
Abstract: Pulsed laser ablation in liquid (PLAL) is gradually becoming an attractive approach for nanomaterial fabrication because it is a chemically simple and clean method with high product purity. We studied the laser interaction with bulk target and particle products in detail, including mechanism process, target morphology and nanoparticle products. We captured three oscillations of one bubble after laser ablates the bulk target and calculated the variation of pressure and temperature inside the bubble. The results show that the first bubble oscillation has greatest impact on the nanomaterial synthesis, and the most powerful stages for the material synthesis during all the bubble oscillations are the beginning of each expansions and the end of each shrinks. Nanomaterial releases from the bubble at the end of each oscillations. In addition, based on the analysis of ablation cavity on the target, it is found that the cavity depth increases with the number of laser pulses, and then the depth tends to be under saturation status, which means it is difficult to obtain great improvement of the nanomaterial productivity just by prolonging the laser irradiation time. More importantly, the strong interaction between laser and particle products is presented clearly by time-resolved shadowgraphy, which can contributed to the modification of nanoparticle products.
TL;DR: In this paper, the authors studied the current densityvoltage (J − V) characteristics of dissimilar metal-insulator-metal (MIM) nanoscale tunneling junctions using a self-consistent quantum model.
Abstract: We study the current density-voltage (J − V) characteristics of dissimilar metal-insulator-metal (MIM) nanoscale tunneling junctions using a self-consistent quantum model. The model includes emissions from both cathode and anode, and the effects of image charge potential, space charge and exchange correlation potential. The J − V curves span three regimes: direct tunneling, field emission, and space-charge-limited regime. Unlike similar MIM junctions, the J − V curves are polarity dependent. The forward (higher work function metal is negatively biased) and reverse (higher work function metal is positively biased) bias J − V curves and their crossover behaviors are examined in detail for various regimes, over a wide range of material properties (work function of the electrodes, electron affinity and permittivity of the insulator). It is found that the asymmetry between the current density profiles increases with the work function difference between the electrodes, insulator layer thickness and relative permittivity of the insulator. This asymmetry is profound in the field emission regime and insignificant in the direct tunneling, and space charge limited regimes.
TL;DR: In this article, the authors investigated the heat transfer in partially ionized Erying-Powell liquid containing four types of nano-particles and found that the rate of transfer of heat is significantly influenced by Hall and ion slip parameters.
Abstract: Heat transfer in partially ionized Erying-Powell liquid containing four types of nano-particles is discussed in this manuscript. Mathematical models for the mixture Erying-Powell plasma and nano-particles are developed and are solved by using finite element method (FEM). Numerical computations are carried out under tolerance 10-5. Physical parameters have significant effects on both thermal boundary layer thicknesses and momentum boundary layer thicknesses. Shear stresses at the surface can be minimized by the Hall and ion slip currents whereas the shear stresses at the sheet for Erying-Powell fluid are high as comparing to the Newtonian fluid. The rate of transfer of heat is significantly influenced by Hall and ion slip parameters. Highest rate of transfer of heat is observed for the case of TiO2 nano-particles. Therefore, it is recommended to disperse TiO2 nano-particles in Erying-Powell fluid for enhancement of heat transfer in Erying-Powell plasma.
TL;DR: In this paper, the authors performed a systematic study on the PHE and anisotropic magnetoresistance (AMR) of Td-MoTe2, a type-II WSM.
Abstract: Besides the negative longitudinal magnetoresistance (MR), planar Hall effect (PHE) is a newly emerging experimental tool to test the chiral anomaly or nontrivial Berry curvature in Weyl semimetals (WSMs). However, the origins of PHE in various systems are not fully distinguished and understood. Here we perform a systematic study on the PHE and anisotropic MR (AMR) of Td-MoTe2, a type-II WSM. Although the PHE and AMR curves can be well fitted by the theoretical formulas, we demonstrate that the anisotropic resistivity arises from the orbital MR (OMR), instead of the negative MR as expected in the chiral anomaly effect. In contrast, the positive MR indicates that the large OMR dominates over the chiral anomaly effect. This explains why it is difficult to measure negative MR in type-II WSMs. We argue that the measured PHE can be related with the chiral anomaly only when the negative MR is simultaneously observed.
TL;DR: In this article, it was shown that the mass of a bit of information at room temperature (300K) is 3.19 × 10-38 Kg, and that the amount of digital information in a data storage device would increase by a small amount when it was full of digital data relative to its mass in erased state.
Abstract: Landauer’s principle formulated in 1961 states that logical irreversibility implies physical irreversibility and demonstrated that information is physical. Here we formulate a new principle of mass-energy-information equivalence proposing that a bit of information is not just physical, as already demonstrated, but it has a finite and quantifiable mass while it stores information. In this framework, it is shown that the mass of a bit of information at room temperature (300K) is 3.19 × 10-38 Kg. To test the hypothesis we propose here an experiment, predicting that the mass of a data storage device would increase by a small amount when is full of digital information relative to its mass in erased state. For 1Tb device the estimated mass change is 2.5 × 10-25 Kg.
TL;DR: In this article, a coordinated microstructural and crystallographic orientation distribution analysis explicitly demonstrated that CdSe tends to grow in nano-sized columns with hexagonal c-axis parallel to its growth direction on glass substrate.
Abstract: Nano-crystalline CdSe thin films of different thicknesses under sub-micron range were deposited on glass substrate via thermal evaporation route. A gradual deterioration in film crystallinity confirmed by XRD line profile analysis has been accompanied by a reduction in Cd to Se molar ratio as the film thickness decreases. A coordinated microstructural and crystallographic orientation distribution analysis explicitly demonstrated that CdSe tends to grow in nano-sized columns with hexagonal c-axis parallel to its growth direction on glass substrate. A thickness dependence of structural evolution was discussed in terms of aspect ratio of the columnar structure and dispersion in orientation of hexagonal (002) basal plane. The variation in the spectra of optical constants [n(λ), k(λ)] obtained from Swanepoel envelop method was interpreted in terms of crystallographic defects arising from stoichiometric disorder which was also accounted for the observed thickness dependent shifts in band gap and valence band split energy. The bathochromic shifts in dielectric and energy loss functions, optical conductivity, skin depth and cut-off energy were discussed in detail along with the variations in their spectral shapes in connection with the dispersion in the real and imaginary parts of complex refractive index, which might shed a new light upon holistic comprehension of thickness dependent optical properties of other chalcogenide semiconducting thin films.
ULTra1, Russian Academy of Sciences2, Moscow State Institute of Radio Engineering, Electronics and Automation3, Moscow Institute of Physics and Technology4, University of Aizu5, Tohoku University6, Rensselaer Polytechnic Institute7, École Polytechnique de Montréal8, Bauman Moscow State Technical University9
TL;DR: In this article, a plasmon-assisted terahertz (THz) photoconductive antenna (PCA) for THz pulse generation at low-power optical pumps is presented.
Abstract: We report on the design, optimization and fabrication of a plasmon-assisted terahertz (THz) photoconductive antenna (PCA) for THz pulse generation at low-power optical pumps. The PCA features a high aspect ratio dielectric-embedded plasmonic Au grating placed into the photoconductive gap. Additionally, Si3N4-passivation of the photoconductor and the Al2O3-antireflection coating are used to further enhance antenna performance. For comparative analysis of the THz photocurrents, THz waveforms and THz power spectra we introduced the THz photocurrent δi and the THz power enhancement δTHz factors, which are defined as ratios between the THz photocurrents and the THz power spectra for the plasmon-assisted and conventional PCAs. We demonstrated superior performance of the plasmon-assisted PCA δi=30 and δTHz=3 ⋅ 103 at the lowest optical pump power of P=0.1 mW. Nevertheless the increase to P=10 mW lead to monotonically decrease in the both values to δi=2 and δTHz=102 due to screening effects. These results demonstrate a strong potential of the plasmonic PCA for operation with low-power lasers, thus, opening opportunities for the development of portable and cost-effective THz spectrometers and imaging systems.
TL;DR: In this paper, the authors applied predictive calculations based on density functional theory and density functional perturbation theory to understand the vibrational properties, phonon-phonon interactions, and electron-Phonon coupling of β-Ga2O3.
Abstract: The wide band gap semiconductor β-Ga2O3 shows promise for applications in high-power and high-temperature electronics. The phonons of β-Ga2O3 play a crucial role in determining its important material characteristics for these applications such as its thermal transport, carrier mobility, and breakdown voltage. In this work, we apply predictive calculations based on density functional theory and density functional perturbation theory to understand the vibrational properties, phonon-phonon interactions, and electron-phonon coupling of β-Ga2O3. We calculate the directionally dependent phonon dispersion, including the effects of LO-TO splitting and isotope substitution, and quantify the frequencies of the infrared and Raman-active modes, the sound velocities, and the heat capacity of the material. Our calculated optical-mode Gruneisen parameters reflect the anharmonicity of the monoclinic crystal structure of β-Ga2O3 and help explain its low thermal conductivity. We also evaluate the electron-phonon coupling matrix elements for the lowest conduction band to determine the phonon mode that limits the mobility at room temperature, which we identified as a polar-optical mode with a phonon energy of 29 meV. We further apply these matrix elements to estimate the breakdown field of β-Ga2O3. Our theoretical characterization of the vibrational properties of β-Ga2O3 highlights its viability for high-power electronic applications and provides a path for experimental development of materials for improved performance in devices.
TL;DR: In this paper, a novel polarization converter based on a metasurface with double w-shaped unit cells is proposed, which can convert linearly polarized incident waves into its cross polarized reflective counterparts in a very wide band with high efficiency.
Abstract: In this work, we design a novel polarization converter based on a metasurface with double w-shaped unit cells. The proposed polarization converter can convert linearly polarized incident waves into its cross polarized reflective counterparts in a very wide band with high efficiency. Theoretical analysis and simulation results show that the proposed polarization converter can achieve a 90° polarization rotation, while the polarization conversion ratio (PCR) is above 90% in the frequency range from 8.44 GHz to 24.96 GHz, and the relative bandwidth can be up to 99%. The measured results agree well with simulation results. The designed double w-shaped metasurface has a very simple geometry, and can realize a highly-efficient and broadband polarization rotation. Therefore, it has practical applications in wireless communication systems, imaging, radar stealth technology, and other fields.
TL;DR: In this paper, a non-linear convection flow of Williamson nanofluid past a radially stretching surface under the application of electric field has been inspected and the simplified joined nonlinear ordinary differential equations are acquired from the partial differential equations which are formulated from the flow problems and then, are altered into dimensionless form employing appropriate resemblance transformation and also, the multivariate nonlinear terms are linearised with the help of Taylor series expansion technique.
Abstract: In the current study, a non-linear convection flow of Williamson nanofluid past a radially stretching surface under the application of electric field has been inspected. The simplified joined non-linear ordinary differential equations are acquired from the partial differential equations which are formulated from the flow problems and then, are altered into dimensionless form employing appropriate resemblance transformation and also, the multivariate nonlinear terms are linearised with the help of Taylor series expansion technique. Then ensuing nonlinear ordinary partial differential equations with matching boundary conditions are solved numerically by utilizing spectral Quasilinearization method (SQLM). The influence of pertinent parameters on different flow fields are probed and conferred in depth by means of numerous plots and tables. The outcomes demonstrate that the velocity profile f′(η) enlarges as the value of electric field E1, buoyancy λ and nonlinear convection λ1 parameters are upgraded. Also, both temperature and concentration profiles augment with a boost in values of magnetic field and thermopherasis parameters. The results also signify that, for bigger values of magnetic field parameter M, the numerical value of local Nusselt number and Sherwood number are declined.
TL;DR: In this article, the authors demonstrate how Rydberg atoms and the phenomena of electromagnetically induced transparency can be used to aid in the recording of a musical instrument in real time as it is played.
Abstract: We demonstrate how Rydberg atoms and the phenomena of electromagnetically induced transparency can be used to aid in the recording of a musical instrument in real time as it is played. Also, by using two different atomic species (cesium and rubidium) in the same vapor cell, we demonstrate the ability to record two guitars simultaneously, where each atomic species detects and allows for the recording of each guitar separately. The approach shows how audio data (the musical composition) can be detected with a quantum system, illustrating that due to the research over the past decade we can now control ensembles of atoms to such an extent that we can use them in this “entertaining” example of recording a musical instrument.
TL;DR: In this paper, a review describes recent advances in the use of magnetic-plasmonic particles (MPPs) for bacteria detection by surface-enhanced Raman scattering (SERS).
Abstract: This review describes recent advances in the use of magnetic-plasmonic particles (MPPs) for bacteria detection by Surface-Enhanced Raman Scattering (SERS). Pathogenic bacteria pollution has always been a major threat to human health and safety. SERS spectroscopy has emerged as a powerful and promising technique for sensitive and selective detection of pathogen bacteria. MPPs are considered as a versatile SERS platform for their excellent plasmonic properties and good magnetic responsiveness. Improved preparation method and typical characterization technique of MPPs are introduced, focusing on the thin and continuous metallic shell covering process. Consequently, the SERS-based sensing methods for bacteria identification were discussed, including the label-free and label-based methods. Finally, an overview of the current state of the field and our perspective on future development directions are given.