bluuebunny/crossref_metadata_2025 huggingface dataset:
Pedestal fluctuation measurements with charge exchange imaging at the DIII-D tokamak
Authors: Major M. R. , McKee G. R. , Geiger B. , Hartog D. J. Den , Jaehnig K. , Seyfert C. , Smith D. R. , Stewart S. D. , Yan Z.
Published: November 2022

A new high radial resolution 2D multichannel Charge eXchange Imaging (CXI) diagnostic is under development for deployment at DIII-D. The diagnostic system will measure low-to-intermediate radial wavenumber carbon density fluctuations by observing the n = 8 − 7 (λ = 529.06 nm) C-VI emission line, resulting from charge exchange collisions between heating neutral beam atoms and the intrinsic carbon ion density. The new CXI diagnostic will provide measurements with ΔR ∼ 0.4 cm to access higher kr instabilities (kr < 8 cm−1) predicted to arise in the steep-gradient region of the H-mode pedestal. The CXI system will feature 60 fiber bundles in a 12 × 5 arrangement, with each bundle consisting of four 1 mm fibers. A custom optical system has been designed to filter and image incoming signals onto an 8 × 8 avalanche photodiode array. Additionally, a novel electronics suite has been designed and commissioned to amplify and digitize the relatively low-intensity carbon signal at a 2 MHz bandwidth. Forward modeling results of the active C-VI emission suggest sufficient signal to noise ratios to resolve turbulent fluctuations. Prototype measurements demonstrate the ability to perform high frequency pedestal measurements.
Current advances on Talbot–Lau x-ray imaging diagnostics for high energy density experiments (invited)
Authors: Valdivia M. P. , Perez-Callejo G. , Bouffetier V. , Collins G. W. , Stoeckl C. , Filkins T. , Mileham C. , Romanofsky M. , Begishev I. A. , Theobald W. , Klein S. R. , Schneider M. K. , Beg F. N. , Casner A. , Stutman D.
Published: November 2022

Talbot–Lau x-ray interferometry is a refraction-based diagnostic that can map electron density gradients through phase-contrast methods. The Talbot–Lau x-ray deflectometry (TXD) diagnostics have been deployed in several high energy density experiments. To improve diagnostic performance, a monochromatic TXD was implemented on the Multi-Tera Watt (MTW) laser using 8 keV multilayer mirrors (Δθ/θ = 4.5%-5.6%). Copper foil and wire targets were irradiated at 1014–1015 W/cm2. Laser pulse length (∼10 to 80 ps) and backlighter target configurations were explored in the context of Moiré fringe contrast and spatial resolution. Foil and wire targets delivered increased contrast <30%. The best spatial resolution (<6 μm) was measured for foils irradiated 80° from the surface. Further TXD diagnostic capability enhancement was achieved through the development of advanced data postprocessing tools. The Talbot Interferometry Analysis (TIA) code enabled x-ray refraction measurements from the MTW monochromatic TXD. Additionally, phase, attenuation, and dark-field maps of an ablating x-pinch load were retrieved through TXD. The images show a dense wire core of ∼60 μm diameter surrounded by low-density material of ∼40 μm thickness with an outer diameter ratio of ∼2.3. Attenuation at 8 keV was measured at ∼20% for the dense core and ∼10% for the low-density material. Instrumental and experimental limitations for monochromatic TXD diagnostics are presented. Enhanced postprocessing capabilities enabled by TIA are demonstrated in the context of high-intensity laser and pulsed power experimental data analysis. Significant advances in TXD diagnostic capabilities are presented. These results inform future diagnostic technique upgrades that will improve the accuracy of plasma characterization through TXD.
Improved order and transport in C60 thin films grown on SiO2 via use of transient templates
Authors: Hagara Jakub , Kim Hongwon , Hagenlocher Jan , Zaluzhnyy Ivan , Gerlach Alexander , Hinderhofer Alexander , Roth Stephan V. , Brütting Wolfgang , Schreiber Frank
Published: November 2022

The performance of C60 semiconducting films is linked to the degree of crystallinity and ordering, properties that strongly depend on the substrate, and growth conditions. Substrate–molecule interactions can be specifically tailored by employing growth templates to achieve a desired thin film structure. However, the presence of a growth template after the film deposition is usually not desirable as it may change the properties of the layer of interest. The ability to remove a growth template without any disruption to the active layer would be highly beneficial. A simple method of template removal by annealing is presented here. A variety of small organic molecules (perfluoropentacene, [6]phenacene, and α-sexithiophene) were used as a growth template to obtain a high-quality well-ordered C60 thin film. In situ grazing-incidence wide-angle x-ray scattering was employed to study the structural changes of C60 thin films during template removal. While a slight disturbance of the thin film structure was observed during template removal caused by evaporated molecules from the growth template escaping through the C60 layer, the disruption is only temporary. When the annealing process is concluded, only the well-ordered C60 thin film directly on top of SiO2 is left, which is not achievable without the use of a growth template. Improved crystallinity and grain size of such a thin film, when compared to preparation without a growth template, lead to a significant improvement of the charge carrier mobility. Importantly, template removal prevents the formation of undesired ambipolar transistor characteristics.
Purcell-induced suppression of superradiance for molecular overlayers on noble atom surfaces
Authors: Fiedler Johannes , Berland Kristian , Buhmann Stefan Yoshi
Published: November 2022

We study the impact of an environment on the electromagnetic responses of a molecule in the presence of a dielectric medium. By applying the dipole–dipole coupling between the molecule’s and the environment’s degrees of freedom, we can reduce the complex system into its components and predict excitation lifetimes of single and few molecules attached to a dielectric surface by knowing the entire quantum–mechanical properties of the molecules, such as transition energies and dipole moments. The derived theory allows for the description of superradiance between two molecules depending on the geometric arrangement between both concerning their separation and orientation with respect to each other. We analyze the possibility of superradiance between two molecules bound to a dielectric sphere and determine a change in the relevant length scale where the usually considered wavelength in free space is replaced with the binding distance, drastically reducing the length scales at which collective effects can take place.
Nanoscale infrared imaging and spectroscopy of few-layer hexagonal boron nitride
Authors: Takamura Makoto , Watanabe Kenji , Taniguchi Takashi , Taniyasu Yoshitaka
Published: November 2022

Nanoscale evaluation of the number of layers and boundaries in two-dimensional (2D) materials is crucial for understanding relationships between structure and property. Here, using scattering-type scanning near-field optical microscopy, we systematically studied on a nanoscale the infrared spectra and imaging of hexagonal boron nitride (h-BN), an ideal 2D insulating material. We revealed that the main factor determining the infrared amplitude changes at an optical frequency of about 1370 cm−1, corresponding to the in-plane phonon mode of h-BN. At lower frequencies, the amplitude is mainly determined by the local dielectric function of a sample and depends on the number of h-BN layers. At higher frequencies, it is affected by the phonon polariton waves of h-BN, and thus edges and grain boundaries of h-BN can be visualized due to the reflection of the waves at the boundary. The infrared spectra show a shoulder peak at higher frequencies, derived from the resonance with the phonon polaritons, in addition to a peak due to the in-plane phonon mode.
Rheology and microstructure of thermoresponsive composite gels of hematite pseudocubes and Pluronic F127
Authors: More Prasanna , Sangitra Surya Narayana , Bohidar H. B. , Pujala Ravi Kumar
Published: November 2022

Stimuli-responsive materials or smart materials are designed materials whose properties can be changed significantly by applying external stimuli, such as stress, electric or magnetic fields, light, temperature, and pH. We report the linear and nonlinear rheological properties of thermoresponsive composite gels based on submicron-sized hematite pseudocube-shaped particles and a triblock copolymer Pluronic F127 (PF127). These novel composites form hard gels at an elevated temperature of 37 °C. For certain concentrations (<20 w/v. %) of hematite pseudocubes in 17.5 w/v. % of PF127, the gel strength is enhanced and the brittleness of the gels decreases. Higher concentrations (>20 w/v. %) of hematite pseudocubes in PF127 result in weaker and fragile gels. We develop an extensive rheological fingerprint using linear and nonlinear rheological studies. Adsorption of PF127 copolymer molecules on the hematite cube surfaces would further assist the formation of particle clusters along with magnetic interactions to be held effectively in the PF127 micellar network at elevated temperatures. The microscopic structure of these composite gels is visualized through a confocal microscope. Our experiments show that addition of hematite cubes up to 20 w/v. % does not change the rapid thermal gelation of PF127 solutions; hence, the hematite–PF127 composite, which transforms into a hard gel near human body temperature of 37 °C, could be suitable for use in smart drug delivery systems.
Effect of oxygen configurations on the mechanical properties of graphene oxide
Authors: Nasr Esfahani Mohammad , Shahbeigi Sepeedeh , Jabbari Masoud
Published: November 2022

Understanding the mechanical properties of graphene oxide (GO) is the primary challenge for applications in materials engineering. The degree of oxidation and concentration of epoxide functional groups have been the main focus of previous mechanochemical studies. This work uses the reactive molecular dynamic simulations to reveal that the mechanical behavior of GO is strongly dependent on the epoxide configuration as well as its distribution. In this study, three main epoxide configurations—including top, bridge, and reside groups—decorate monolayer GO sheets with linear and random distributions. The distortion associated with epoxide groups creates diamond-like structures controlling the mechanical properties. Moreover, the orientation of those epoxide functional groups with applied loads has a dramatic impact on the mechanical response of GO. The effect of external electric fields on the mechanical properties of GO is another objective of this study. Findings exhibit that the electric field enhances the tensile toughness. This study demonstrates new aspects of GO as a functional material with potentials to control the mechanical properties through chemical compositions as well as external electric fields.
Effect of the Stokes boundary layer on the dynamics of particle pairs in an oscillatory flow
Authors: van Overveld T. J. J. M. , Breugem W.-P. , Clercx H. J. H. , Duran-Matute M.
Published: November 2022

The alignment of a pair of spherical particles perpendicular to a horizontally oscillating flow is attributed to a non-zero residual flow, known as steady streaming. This phenomenon is the basis of complex patterns in denser systems, such as particle chains and the initial stages of rolling-grain ripples. Previous studies on such self-organization processes used two distinct systems: an oscillating box filled with viscous fluid and an oscillating channel flow, where the fluid oscillates relative to the bottom boundary. In this paper, we show that particle pair dynamics in these two systems are fundamentally different, due to the presence of a Stokes boundary layer above the bottom in the oscillating channel flow. The results are obtained from direct numerical simulations in which the dynamics of a pair of particles are simulated using an immersed boundary method. The oscillating box and the oscillating channel flow are only equivalent in a limited region of the parameter space, where both the normalized Stokes boundary layer thickness and the normalized relative particle excursion length are small. Overall, the particle dynamics in the oscillating channel flow, compared to the oscillating box, are governed by an additional dimensionless parameter, that is, the particle–fluid density ratio.
Enhanced spreading of surfactant-containing, self-rewetting fluids in pulmonary drug delivery
Authors: Su Haozhe , Li Chunxi , Li Dan , Ye Xuemin
Published: November 2022

We study the enhanced spreading and internal diffusion of a cold, self-rewetting droplet laden with both surfactant and medicine that is placed over a hot liquid film. Spreading is induced by solutocapillary and thermocapillary effects simultaneously. A numerical simulation based on Stokes flow is performed, and the internal velocity map is obtained. The horizontal velocity flux and total medicine absorption are calculated to examine the internal diffusion and transport behaviors for a low-viscosity case and a high-viscosity mucus case. The results show that solutocapillary and thermocapillary effects contribute to droplet spreading positively and negatively, respectively. Self-rewetting fluids enhance spreading by increasing the surface tension gradient and prolonging the time required for spreading to reach a steady regime. For the self-rewetting fluid case at the final calculation time, the thermo-Marangoni number ΣT = 0.03, and the soluto-Marangoni number ΣS = 0.9, the internal diffusion and medicine absorption are enhanced by 9.1% and 8.3% relative to the ordinary fluid, respectively. When a droplet spreads on a high-viscosity mucus at the same Marangoni numbers, both spreading and diffusion are hindered. The spreading enhancement provided by self-rewetting fluids is much smaller than in low-viscosity cases. However, medicine absorption still increases by 11%.
The impact of the electric field of metal ions on the vibrations and internal hydrogen bond strength in alkali metal ion di- and triglycine complexes
Authors: Meyer Katharina A. E. , Nickson Kathleen A. , Garand Etienne
Published: November 2022

Using infrared predissociation spectroscopy of cryogenic ions, we revisit the vibrational spectra of alkali metal ion (Li+, Na+, K+) di- and triglycine complexes. We assign their most stable conformation, which involves metal ion coordination to all C=O groups and an internal NH⋯NH2 hydrogen bond in the peptide backbone. An analysis of the spectral shifts of the OH and C=O stretching vibrations across the different metal ions and peptide chain lengths shows that these are largely caused by the electric field of the metal ion, which varies in strength as a function of the square of the distance. The metal ion–peptide interaction also remotely modulates the strength of internal hydrogen bonding in the peptide backbone via the weakening of the amide C=O bond, resulting in a decrease in internal hydrogen bond strength from Li+ > Na+ > K+.
Measurement of shock roughness due to phase plate speckle imprinting relevant for x-ray diffraction experiments on 3rd and 4th generation light sources
Authors: Gorman Martin G. , Ali Suzanne J. , Celliers Peter M. , Peebles Jonathan L. , Erskine David J. , McNaney James M. , Eggert Jon H. , Smith Raymond F.
Published: November 2022

Laser-shock compression experiments at 3rd and 4th generation light sources generally employ phase plates, which are inserted into the beamline to achieve a repeatable intensity distribution at the focal plane. Here, the laser intensity profile is characterized by a high-contrast, high-frequency laser speckle. Without sufficient smoothing, these laser non-uniformities can translate to a significant pressure distribution within the sample layer and can affect data interpretation in x-ray diffraction experiments. Here, we use a combination of one- and two-dimensional velocity interferometry to directly measure the extent to which spatial frequencies within the laser focal spot intensity pattern are smoothed out during propagation within the laser plasma and a polyimide ablator. We find that the use of thicker polyimide layers results in spatially smoother shock fronts, with the greatest degree of smoothing associated with the highest spatial frequencies. Focal spots with the smallest initial speckle separation produce the most rapid smoothing. Laser systems that employ smoothing by spectral dispersion techniques to rapidly modulate the focal plane intensity distribution are shown to be the most effective ones in producing a spatially smooth shock front. We show that a simple transport model combined with the known polyimide Hugoniot adequately describes the extent of shock smoothness as a function of polyimide thickness. Our results provide a description of spatial structure smoothing across a shock front, which can be used to design targets on x-ray free electron laser facilities.
Background-independent evaluation model for infrared jamming effectiveness of false targets
Authors: Qiu Yongjia , Yang Hua , Zhao Dapeng , Cheng Zhengdong , Zhu Bin , Zhang Qinyu
Published: November 2022

Given the lack of a standardized evaluation system for the infrared jamming effectiveness of false targets, this paper first uses a co-saliency detection model to extract the main parts of the true and false targets. Then the perceptual similarity algorithm is improved by combining the operational requirements of false targets in the infrared band. Finally, a background-independent evaluation model for infrared jamming effectiveness of false targets is constructed. The experimental results show that the model can quantitatively reflect the infrared jamming effectiveness of a single false target and distinguish the infrared jamming effectiveness of different types of false targets. In addition, the model has stronger robustness than traditional evaluation models.
Dual-domain analysis of gun violence incidents in the United States
Authors: James Nick , Menzies Max
Published: November 2022

This paper applies new and recently introduced approaches to study trends in gun violence in the United States. We use techniques in both the time and frequency domain to provide a more complete understanding of gun violence dynamics. We analyze gun violence incidents on a state-by-state basis as recorded by the Gun Violence Archive. We have numerous specific phenomena of focus, including periodicity of incidents, locations in time where behavioral changes occur, and shifts in gun violence patterns since April 2020. First, we implement a recently introduced method of spectral density estimation for nonstationary time series to investigate periodicity on a state-by-state basis, including revealing where periodic behaviors change with time. We can also classify different patterns of behavioral changes among the states. We then aim to understand the most significant shifts in gun violence since numerous key events in 2020, including the COVID-19 pandemic, lockdowns, and periods of civil unrest. Our dual-domain analysis provides a more thorough understanding and challenges numerous widely held conceptions regarding the prevalence of gun violence incidents.
Theoretical and experimental investigation on the low-frequency vibro-acoustic characteristics of a finite locally resonant plate
Authors: Guo Peng , Zhou Qi-zheng , Luo Zi-yin
Published: November 2022

This study investigates the low-frequency vibro-acoustic characteristics of a finite locally resonant (LR) plate. A dynamic model of the finite LR plate consisting of periodic arrays of beam-like resonators attached to a thin aluminum plate with simply supported boundary conditions is established, and the average vibration response and radiated efficiency are theoretically determined by using modal-superposition and harmonic-balance methods. In addition, the study investigates the influence of the parameters and number of additional resonators on the vibro-acoustic performance of the finite LR plate. Finally, a vibration experiment of a finite plate with 8 × 10 uniformly distributed beam-like resonators validates the theoretical analysis results. The numerical and experimental results show that the finite LR plate has a low-frequency bandgap that can suppress the vibration and radiated noise of the structure, and the bandgap position is close to the resonance frequency of resonators. The position and performance of bandgaps can be influenced by changing the parameters and number of resonators. The experimental results show a bandgap ranging from 370 to 425 Hz, which is consistent with the theoretical prediction. The finite LR plates proposed in this study can find potential applications in the attenuation of low-frequency vibration and noise.
Noise suppression method for hydroxyl tagging velocimetry based on generative adversarial networks
Authors: Shao Jun , Wu Junzheng , Ye Jingfeng , Wu Zhenjie , Zhang Zhenrong , Wang Sheng , Li Guohua , Tao Mengmeng , Wu Haolong , Yi Aiping , Hu Zhiyun
Published: November 2022

Hydroxyl tagging velocimetry (HTV) technology is crucial in the velocimetry diagnosis of combustion flow fields. However, obtaining accurate HTV information in practical engineering applications is difficult because of complex flow fields and background noise interference. Therefore, for noise suppression, we proposed a generative adversarial network method for targeted network training based on the analysis of HTV image noise characteristics in a complex flow field and the construction of a high-confidence noise description model. The proposed method can effectively suppress noise in HTV experimental data, improve the signal-to-noise ratio of HTV images, and improve the accuracy of HTV measurement.
Effects of hot phonons and thermal stress in micro-Raman spectra of molybdenum disulfide
Authors: Sokalski Peter , Han Zherui , Fleming Gabriella Coloyan , Smith Brandon , Sullivan Sean E. , Huang Rui , Ruan Xiulin , Shi Li
Published: November 2022

Micro-Raman spectroscopy has become an important tool in probing thermophysical properties in functional materials. Localized heating by the focused Raman excitation laser beam can produce both stress and local nonequilibrium phonons in the material. Here, we investigate the effects of hot optical phonons in the Raman spectra of molybdenum disulfide and distinguish them from those caused by thermally induced compressive stress, which causes a Raman frequency blue shift. We use a thermomechanical analysis to correct for this stress effect in the equivalent lattice temperature extracted from the measured Raman peak shift. When the heating Gaussian laser beam is reduced to 0.71 μm, the corrected peak shift temperature rise is 17% and 8%, respectively, higher than those determined from the measured peak shift and linewidth without the stress correction, and 32% smaller than the optical phonon temperature rise obtained from the anti-Stokes to Stokes intensity ratio. This nonequilibrium between the hot optical phonons and the lattice vanishes as the beam width increases to 1.53 μm. Much less pronounced than those reported in prior micro-Raman measurements of suspended graphene, this observed hot phonon behavior agrees with a first-principles based multitemperature model of overpopulated zone-center optical phonons compared to other optical phonons in the Brillouin zone and acoustic phonons of this prototypical transition metal dichalcogenide. The findings provide detailed insight into the energy relaxation processes in this emerging electronic and optoelectronic material and clarify an important question in micro-Raman measurements of thermal transport in this and other two-dimensional materials.
Approaching the basis-set limit of the dRPA correlation energy with explicitly correlated and projector augmented-wave methods
Authors: Humer Moritz , Harding Michael E. , Schlipf Martin , Taheridehkordi Amir , Sukurma Zoran , Klopper Wim , Kresse Georg
Published: November 2022

The direct random-phase approximation (dRPA) is used to calculate and compare atomization energies for the HEAT set and ten selected molecules of the G2-1 set using both plane waves and Gaussian-type orbitals. We describe detailed procedures to obtain highly accurate and well converged results for the projector augmented-wave method as implemented in the Vienna Ab initio Simulation Package as well as the explicitly correlated dRPA-F12 method as implemented in the TURBOMOLE package. The two approaches agree within chemical accuracy (1 kcal/mol) for the atomization energies of all considered molecules, both for the exact exchange as well as for the RPA. The root mean-square deviation is 0.41 kcal/mol for the exact exchange (evaluated using density functional theory orbitals) and 0.33 kcal/mol for exact exchange plus correlation from the RPA.
Zero-Mach limit of the compressible Navier–Stokes–Korteweg equations
Authors: Ju Qiangchang , Xu Jianjun
Published: November 2022

We consider the Cauchy problem for the compressible Navier–Stokes–Korteweg system in three dimensions. Under the assumption of the global existence of strong solutions to incompressible Navier–Stokes equations, we demonstrate that the compressible Navier–Stokes–Korteweg system admits a global unique strong solution without smallness restrictions on initial data when the Mach number is sufficiently small. Furthermore, we derive the uniform convergence of strong solutions for compressible Navier–Stokes–Korteweg equations toward those for incompressible Navier–Stokes equations as long as the solution of the limiting system exists.
Modeling the mass transfer at acoustically generated bubble interface using Rayleigh–Plesset equation second-order derivatives
Authors: Al Bishtawi Basel , Mustapha Khameel Bayo , Scribano Gianfranco
Published: November 2022

One of the many ways of cavitation utilized for process intensification is through acoustically inducing it. As acoustic cavitation gained traction in recent industrial works, numerical modeling became an important study tool to scrutinize and optimize acoustic cavitation applications. However, available hydrodynamic cavitation models are found incapable of accurately predicting acoustic cavitation structures and flow features. This could source from the oversimplification of the Rayleigh–Plesset equation or from obscure effects of empirical model constants. To address this issue, new mass transfer source terms for Zwart–Gerber–Belamri model were derived based on the consideration of Rayleigh–Plesset's second-order derivatives. In addition, a design of experiments statistical approach, coupled with Monte Carlo simulations, was implemented to assess the influence of empirical model constants on the model's performance by examining variations in amplitude and frequency responses. Moreover, a set of optimized model constants was obtained: evaporation constant = 17.359 88, condensation constant = 0.1, Bubble Radius = 25 × 10−6 m, and Nucleation Site Volume Fraction = 5 × 10−4, to obtain a maximum pressure and frequency of 3.62 bar and 4128.73 Hz, respectively. The new model, with the new constants, was configured into ANSYS Fluent 22.1 and validated against experimental values. The new model resulted with maximum pressure and frequency of 3.48 bar and 4894.56 Hz, respectively, validating the statistical model and showing drastic improvement in qualitatively and quantitatively capturing acoustic cavitation.
Vibrational mode-specific polarization effect in circularly polarized stimulated Raman scattering
Authors: Li Yuhui , Li Tao , Yu Yuanqin , Sun Jin , Zhou Xiaoguo , Zhang Rui , Liu Shilin
Published: November 2022

As one of the popular coherent Raman scattering techniques, stimulated Raman scattering (SRS) has made significant progress in recent years, especially in label-free biological imaging. Polarization provides an additional degree of freedom to manipulate the SRS process. In previous studies, only linearly polarized SRS was fully investigated, in which both pump and Stokes laser fields are linearly polarized. Here, we theoretically analyzed the SRS process excited by two circularly polarized laser fields and then experimentally demonstrated it by taking a spherical symmetric CH4 molecule as a model system. The experimental results are in good agreement with the theoretical ones. It is shown that circularly polarized SRS (CP-SRS) has unique characteristics different from linear polarization. When the handedness of circular polarization states of two laser fields is the same, CP-SRS further suppresses the depolarized vibrational band while keeping the polarized band almost unaffected. On the other hand, when the handedness is opposite, CP-SRS enhances the depolarized band while suppressing the polarized band. Therefore, the CP-SRS not only allows us to resolve the symmetry of vibrational modes but also can enhance vibrational contrast based on symmetry selectivity by suppressing or enhancing the signal from a specific vibrational mode. These results will have potential applications in improving chemical selectivity and imaging contrast as well as spectral resolution SRS microscopy. In addition, the CP-SRS has the ability to determine the depolarization ratio ρ and identify the overlapping Raman bands.
Strong–weak duality via Jordan–Wigner transformation: Using fermionic methods for strongly correlated su(2) spin systems
Authors: Henderson Thomas M. , Chen Guo P. , Scuseria Gustavo E.
Published: November 2022

The Jordan–Wigner transformation establishes a duality between su(2) and fermionic algebras. We present qualitative arguments and numerical evidence that when mapping spins to fermions, the transformation makes strong correlation weaker, as demonstrated by the Hartree–Fock approximation to the transformed Hamiltonian. This result can be rationalized in terms of rank reduction of spin shift terms when transformed to fermions. Conversely, the mapping of fermions to qubits makes strong correlation stronger, complicating its solution when one uses qubit-based correlators. The presence of string operators poses challenges to the implementation of quantum chemistry methods on classical computers, but these can be dealt with using established techniques of low computational cost. Our proof of principle results for XXZ and J1-J2 Heisenberg (in 1D and 2D) indicates that the JW transformed fermionic Hamiltonian has reduced complexity in key regions of their phase diagrams and provides a better starting point for addressing challenging spin problems.
Multiplicative potentials for kinetic energy and exact exchange
Authors: Oueis Yan , Staroverov Viktor N.
Published: November 2022

Harriman showed that within finite basis sets of one-electron functions that form linearly independent products (LIP), differential and integral operators can be represented exactly and unambiguously by multiplicative (local) potentials. Although almost no standard basis sets of quantum chemistry form LIPs in a numerical sense, occupied self-consistent field (SCF) orbitals routinely do so. Using minimal LIP basis sets of occupied SCF orbitals, we construct multiplicative potentials for electronic kinetic energy and exact exchange that reproduce the Hartree–Fock and Kohn–Sham Hamiltonian matrices and electron densities for atoms and molecules. The results highlight fundamental differences between local and nonlocal operators and suggest a practical possibility of developing exact kinetic energy functionals within finite basis sets by using effective local potentials.
Wavepacket dynamics of the excited (S1) state of 2,5-difluoroaniline by accidental resonance with the Rydberg states
Authors: Wei Jie , Cao Ling , Song Xinli , Wang Yanmei , Zhang Song , Zhang Bing
Published: November 2022

Coherent nuclear wavepacket behavior obtained by time-resolved spectroscopy is a good choice to capture the real-time evolution of molecular configuration. Using femtosecond time-resolved photoelectron imaging, we investigate the real-time evolution of the vibrational wavepacket of 2,5-difluoroaniline following the coherent excitation of an out-of-plane vibrational mode in the S1 state at 289.8 nm. Probed by an accidental resonance with the Rydberg states, the periodic oscillations with the frequency of 99 cm−1 are observed from the photoelectron kinetic energy (PKE) distributions, corresponding to the energy difference between the out-of-plane mode X10 of C–F bond and the band origin. Moreover, phase reversal of π rad between 0.66–0.75 and 1.00–1.08 eV is also observed in the PKE region. Combined with the scan of the potential energy surface in the ground cationic D0 state, the observed two ionization channels corresponding to different phases are attributed to the periodic geometry changes between the planar and the non-planar structures when the coherent wavepacket evolves from the initial vertical Franck–Condon region toward the global minimum of the S1 potential energy surface.
MemComputing: When memory becomes a computing tool
Authors: Di Ventra Massimiliano
Published: November 2022

A physical system that retrieves information from the past and acts on it appropriately can efficiently solve difficult combinatorial-optimization problems.
Paul Langevin, U-boats, and ultrasonics
Authors: Duck Francis
Published: November 2022

Created in 1917 to detect German U-boats, Paul Langevin’s piezoelectric quartz transducer remains the foundation of all modern ultrasonic techniques.
Self-denigration in academic discourse
Authors: Mayahi Nadia , Jalilifar Alireza
Published: November 2022

Using the methodology of Grounded Theory, this study aims to identify and analyze the perceptions and functions of
self-denigration in dissertation defenses. The data comprises transcripts of two focus group discussions and the disputation
sections of a corpus of 53 applied linguistics doctoral defense sessions gathered from 14 Iranian state universities between 2019
and 2021. The findings suggest that self-denigration depends to a great extent on the role of the participants in a disputation,
and it is used before or after a criticism or a response to criticism. The analysis of the data revealed that self-denigration as
a sign of respectfulness and modesty in a defense contributes to social decorum, diffidence, coercive self-deprecation, contrived
modesty, or flamboyance. This study highlights the importance of self-denigration in the oral academic discourse of EFL defense
sessions and has pedagogical implications for oral academic literacy practices.
Political speeches
Authors: Tincheva Nelly
Published: November 2022

This chapter offers a principled theoretical
suggestion on the basis of which political speeches could be
(re-)defined and the multiple simultaneous functions performed by a
political speech could be analyzed. The chapter addresses issues
concerning (a) the main types of functions a political speech can
perform, (b) the cognitive explanation of the presence of these
specific types of functions, and (c) the cognitive explanation of
the simultaneous operation of these specific types of functions.

The main line of argumentation supports a view in
which at least three cognitive mechanisms need to be taken into
account in order for us to be able to explain what a political
speech is and how it functions. These cognitive mechanisms include
conceptual metaphoric transfer, TW and DW construction and overlaps,
and gestalt shifts in profiling.

The theoretical model proposed derives from two
questionnaire-based studies reported here. The model is subsequently
verified against a dataset of 50 speeches by British and American
politicians delivered within the span of the last 80 years.
A corpus-based look at time metaphors
Authors: Valenzuela Javier , Illán Castillo Rosa
Published: November 2022

Motion-based metaphors of time have been thoroughly discussed in the literature, but some aspects still remain underexplored. The present chapter addresses one of these areas, namely, the lexical richness of the motion verbs found in temporal expressions. We present the findings of a corpus study of motion expressions of time in television news. Using a large set of data, we show that motion verbs that are not conventionally associated with the expression of time, such as crawl and roll, are used alongside the more typical ones (e.g., come, approach). The results suggest that language users are in fact far more creative than it has been assumed so far, thus challenging what is typically perceived as an everyday metaphor of time.
Time moves more often in poetry
Authors: Illán Castillo Rosa , Cristóbal Pagán Cánovas
Published: November 2022

It is assumed that humans use spatial concepts to think and speak about time. In this chapter we analyze the spatialization of time in five different literary and non-literary corpora by looking at the frequency with which time units (minutes, hours, days, weeks, months, years, and centuries) appear as the subject of a motion verb. The results reveal that there is a tendency to spatialize time more often in literature – especially in lyric poetry – than in other non-literary linguistic contexts. This supports the idea that meaning construction cannot be reduced to a direct transfer-based model, but rather requires an elaborate network of conceptual integration that opportunistically – and creatively – adjusts mappings and integrations to goals.
Creative visual metaphors of protracted and frozen time in autobiographical comics about depression
Authors: El Refaie Elisabeth
Published: November 2022

One common but lesser-known symptom of depression is distorted temporal perception. This chapter analyzes visual metaphors in seven graphic memoirs about depression, revealing the unique opportunities for creativity in the evocation of subjective time offered by this genre. Specifically, the authors of these works use different combinations of “pictorial” and “spatial” metaphors (El Refaie 2019) to convey their sense of time slowing down or freezing, and of being out of sync with other people. These findings are related to Conceptual metaphor theory, including Stocker’s (2014) notion of “spacetime”.
From “slow lettuce” to “striated time”
Authors: Besada José L.
Published: November 2022

Many trends of the 20th (and 21st) century Western art music have emphasized the value of individual novelty when conceiving art. This ideological imperative has boosted composers’ creativity for developing personal and almost ex novo conceptions of musical attributes and parameters, time among them. Some of these conceptions can be retrieved in the several traces of their compositional practices. My study focuses on composer and conductor Pierre Boulez (1925–2016), and his presentation of some original formulae for managing musical temporality. Through his essays, compositional sketches, scores, and performances, I analyze several cross-modal features, based on embodied experience, and image schemata underlying his time conceptualizations, with the help of cognitive science and in quest of a generalizable model.
Time in Chinese hands
Authors: Gu Yan
Published: November 2022

This chapter examines how Chinese people (Mandarin monolinguals; Mandarin-English bilinguals; deaf Chinese Sign Language (CSL) signers; Mandarin learners of CSL) use gestures and signs to creatively represent time. All groups spatialize time on the lateral, vertical, and sagittal axes, but differ in their choices of axes and directions of movements. For instance, Mandarin-English bilinguals produce more vertical time gestures in Mandarin than in English. Mandarin speakers can produce past-in-front and past-at-back gestures, whereas CSL deaf signers only exploit past-at-back signs. Mandarin learners of CSL perform more past-at-back gestures than Mandarin-speaking non-signers. In short, cultural, linguistic, and bodily experiences can jointly shape how Chinese people express time creatively in different modalities.
Les études basques comme sujet d’enquête
Authors: Anduaga Aitor
Published: November 2022

Cet article analyse le processus de disciplinarisation des études basques –ou leur constitution en tant que sujet d’enquête académique —comme exemple d’area studydans une nation sans État. A cette fin, il décrit la confluence des courants discursifs en bascologie à la fin du XIXesiècle dans un contexte de création des disciplines de la linguistique et de la philologie romane en Europe et de la “renaissance” de la langue et de l’identité basques. L’article soutient que ce processus s’est distingué par l’intégration de deux traditions —l’une “locale”, unie à la patrie basque, et l’autre “étrangère”, liée à la bascologie européenne— dans la stratégie de publication de laRevue Internationale des Études Basques(fondée en 1907). L’étude montre comment les conventions discursives dans lesquelles ces traditions ont été insérées ont influencé non seulement la production de connaissances, mais aussi la manière dont le sujet des études basques s’est construit à travers la fondation d’un congrès et d’une revue internationaux, et la canonisation des textes originaux basques.
Is there a social history of the Catalan language?
Authors: Nicolàs Miquel
Published: November 2022

Over the last century, historical linguistics has produced notable studies on the formal evolution of the Catalan language. Moreover, in recent decades Catalan sociolinguistics has been developed, connecting theory and empirical description to language policy. However, a social history of the Catalan language has not been developed nor historical sociolinguistics, strictly speaking, bar a few random examples. The reasons for this deficit are both internal (the limitations of the subject matter, the inertia and the stagnation of philological studies…) and external (the socio-political and market constraints imposed on the Catalan language). We therefore propose to move towards a new paradigm in which the linguistic diachrony is integrated within social sciences, open to self-criticism and to overcoming ideological apriorism.
Equilibria and stability of the two-balloon system
Authors: Lemons Don S , Lipscombe Trevor C
Published: November 2022

We demonstrate that the various equilibria that can be realized by two, identical, inflated, party balloons, each attached to one end of a rigid plastic tube, are stable—a demonstration based on A N Gent’s equation of state, which relates the pressure of the air contained with a thin elastic sphere to the sphere radius. Measurements on 12 inch party balloons illustrate these stable equilibria.
Microscale nuclear magnetic resonance gradient chip
Authors: Meissner M V , While P T , Mager D , Korvink J G
Published: November 2022

We propose a design, micro fabrication process, and nuclear magnetic resonance (NMR) based evaluation, of a magnetic field gradient chip. The uni-axial linear z-gradient coil design was computed by a stream-function method, with the optimisation goal to exhibit minimum power dissipation. The gradient coils were implemented on two bi-planes, which were built-up with Cu electroplating in combination with photo definable dry-film laminates. In the presented fabrication process, the initial seed layer served as a self-aligning back-side mask to define the electroplating mould, and also to implement resistive temperature detectors. The coil design and the electroplating process were tailored to enhance the electroplated height to construct low-resistive coils. Thermographic imaging in combination with the integrated temperature sensors allowed for investigating the heat-up, in order to analyse the current rating of the coil dual stack. The gradient coil was assembled with a radio frequency micro coil in a flip-chip configuration. To demonstrate the field linearity, a micro-engineered phantom was fabricated and subjected to a one-dimensional NMR experiment.
A novel model for calculating the impedance of arbitrarily-shaped coils with perpendicular to the planar medium
Authors: Dehui Wu , Hao Feng
Published: November 2022

Some studies have shown that coils placed perpendicular to conductors have excellent detection effect for specific defects in eddy-current testing (ECT), where the impedance is an important parameter. The impedance calculation for perpendicular coil is more complex than that for parallel coil, and currently the main focus is on the impedance analysis of circular and rectangular coils. In this paper, a closed formula for the impedance of a coil with arbitrary-shape perpendicular to the conductor is given based on the second order vector position method. In the proposed model, a novel shape and position function is defined to extend the coil application to arbitrary cross-sectional shapes. Meanwhile, experimental comparisons are conducted to evaluate the impedance of various coils on an aluminum plate. The results illustrated that the experimental values are in perfect agreement with the calculated ones. Therefore, the proposed model can provide guidance for the impedance calculation of arbitrarily-shaped coils in eddy current testing.
A novel method for identifying rotor unbalance parameters in the time domain
Authors: Sun Xun , Cui Jiwen , Chen Yue , Tan Jiubin
Published: November 2022

In this paper, we propose an unbalance parameters identification method based on a time-domain response that combines a matrix equation and spectral correction technique (SCT). Numerical simulations and experiments are conducted to demonstrate the performance of the proposed method. A commonly used method for identifying unbalance parameters based on time-domain response is the equivalent load method, in which the modal expansion technique (MET) is used to extend the vibration response of a few of measurement points to the vibration response of all degrees of freedom of the model. However, this technique may result in incorrect identification. To solve the above problem, we first directly derive a matrix equation describing the relationship between the vibration response at the measurement point and the unbalanced forces based on the state space equations of the reduced-order model. This process avoids the application of METs and effectively improves the robustness of the identification results. The unbalanced force can then be obtained based on the vibration response by solving the matrix equation using the regularisation method. Finally, the unbalance parameters are obtained by processing the unbalanced force using the SCT. The simulation and experimental results show that, compared with the traditional equivalent load method, the proposed method can identify the unbalance parameters with higher accuracy, which proves its application prospect in balancing machines and field balancing.
Damage detection in plate structures based on baseline construction of ultrasonic Lamb wave using designed mobile transducer set
Authors: Zhou Kai , Yuan Hongqiang , Yin Jiangshui , Xu Hao
Published: November 2022

The ultrasonic Lamb wave-based damage detection method is widely used in plate structures. Due to the multimode characteristic, the collected Lamb wave signals are very complicated, making it difficult to obtain damage information. This paper proposes a damage imaging algorithm based on the baseline construction of the Lamb wave for plate structures. A mobile transducer set including two transducers is designed for Lamb wave excitation and signal collection. To extract damage scattering signals, the response of the signal in healthy areas (the structural response signal) is measured as a temporarily constructed baseline signal. The structural response signal is obtained based on the identified healthy signals collected in different areas of the same structure. Damage scattering signals are extracted as the differences between the current signals and the structural response signal. Damage indexes are calculated based on the damage scattering signals to locate the damage with the imaging algorithm. A damage detection experiment is conducted on an aluminum plate to verify this proposed method. The imaging result is in good agreement with the damage location in the experiment. This paper provides a potential alternative for damage detection of plate structures in practice.