Field Propagation Research Articles

Effects of mix components on mechanical properties of marine volcanic-scoria concrete under axial compression

This study systematically investigated the mechanical properties of marine volcanic-scoria concrete (MVSC) under the coupled effects of the mix components. Six groups and 408 specimens were used, including four different experimental parameters: types of coarse and fine aggregates (volcanic-scoria aggregate and natural aggregate), types of mixing water (seawater and freshwater), and age (days 7, 14, and 28). The macro-mechanical properties, mechanism, and microstructure of MVSC were analysed using a novel test system, including an axial compression test, digital image correlation (DIC) method, and scanning-electron microscopy (SEM). Variations in the failure pattern, stress–strain curve, deformation field distribution, crack initiation, and propagation of MVSC were studied. Generally, the failure of MVSC is brittle compared to that of ordinary concrete (OC). The cubic compressive strengths of MVSC at day 7 and 14 were 82.7% and 91.7% of the cubic compressive strength at day 28, respectively. The splitting tensile strength of MVSC was 7.3% higher on average than that of OC. The mix components changed the strength of MVSC. Seawater and sea sand accelerated the development of compressive strength, volcanic-scoria fine, and coarse aggregates (VSFA and VSCA, respectively) enhanced the tensile strength. After using volcanic-scoria aggregates, the curvature of the concrete stress–strain curve decreased; however, the curve declined sharply after the peak stress (σmax). Compared with OC, the ductility of MVSC decreased by an average of 17.2%, whereas the peak strain increased by 6.9%. Furthermore, VSCA significantly changed the displacement distributions of the specimen, whereas the impacts of the mixing water and fine aggregate were small. The crack initiation and propagation of MVSC were different from those of OC; that is, microcracks first appeared in VSCA, and their characteristics propagated slowly before σmax. Finally, a theoretical model of the MVSC stress–strain curve involving the coupled impacts of the mix components was established, which can prompt the practical application of MVSC structures.

Probing the Gold/Water Interface with Surface-Specific Spectroscopy.

Water is an integral component in electrochemistry, in the generation of the electric double layer, and in the propagation of the interfacial electric fields into the solution; however, probing the molecular-level structure of interfacial water near functioning electrode surfaces remains challenging. Due to the surface-specificity, sum-frequency-generation (SFG) spectroscopy offers an opportunity to investigate the structure of water near working electrochemical interfaces but probing the hydrogen-bonded structure of water at this buried electrode-electrolyte interface was thought to be impossible. Propagating the laser beams through the solvent leads to a large attenuation of the infrared light due to the absorption of water, and interrogating the interface by sending the laser beams through the electrode normally obscures the SFG spectra due to the large nonlinear response of conduction band electrons. Here, we show that the latter limitation is removed when the gold layer is thin. To demonstrate this, we prepared Au gradient films on CaF2 with a thickness between 0 and 8 nm. SFG spectra of the Au gradient films in contact with H2O and D2O demonstrate that resonant water SFG spectra can be obtained using Au films with a thickness of ∼2 nm or less. The measured spectra are distinctively different from the frequency-dependent Fresnel factors of the interface, suggesting that the features we observe in the OH stretching region indeed do not arise from the nonresonant response of the Au films. With the newfound ability to probe interfacial solvent structure at electrode/aqueous interfaces, we hope to provide insights into more efficient electrolyte composition and electrode design.

T-duality of D-brane versus O-plane actions

It is known that, in the static gauge, the world-volume and the transverse Kaluza-Klein (KK) reductions of the O-plane effective actions on a circle satisfy the T-duality constraint for arbitrary base space background. In this paper we show that due to the presence of the second fundamental form in the D-brane couplings at order α′ and higher, the T-duality is satisfied only for a subclass of the couplings for arbitrary base space background. They are m = 0 couplings where m is the number of overset{sim }{B} -field (without derivative on it). For m > 0 couplings, the base space metric must be block-diagonal and the momentum U(1) vector field in the transverse reduction must be zero. However, the derivatives of the metric and the vector field are arbitrary.Using the assumption that the effective actions at the critical dimension are background independent, we then show that the T-duality constraint for the couplings at order α′ and for m = 0, fixes completely both bulk and boundary actions. These couplings indicate that the propagators of the massless open string fields receive α′-correction. We have also imposed the T-duality constraint on m = 1, 2, 3, 4 couplings. Because of the above restriction on the base space background in these cases, however, the T-duality can only partially fix the couplings for m > 0. This study shows that the Dirac-Born-Infeld (DBI) factor appears in both bulk and boundary actions at order α′.

Research on Fault Activation and Its Influencing Factors on the Barrier Effect of Rock Mass Movement Induced by Mining

For the study of the driving forces behind fault activation and its influencing factors on the barrier effect of rock mass movement under the influence of mining, the discrete element numerical simulation software 3DEC was used for the analysis of the impact on the distance to mining area from fault, the buried depth of the upper boundary of the fault, the dip angle of fault, the size of the mining area and the thickness of the fault zone respectively. The results show that the mining areas are closer to the fault as distances decrease, the burial depth of the upper boundary of the fault increases, and the size of the mining area increases, the fault is easier to activate, and fault activation has a stronger barrier impact on displacement field and stress field propagation. When the fault is cut into the goaf, the difference of rock displacement in both directions of the fault increases when the dip of the fault increases, and the fault is more susceptible to instability and activation. The barrier strength grows with the increase of the thickness of the fault fracture zone. The results of this study have important implications for the guard against and control of deep mining-related fault activation disasters.

Research on spatial frequency shift super-resolution imaging based on evanescent wave illumination

<sec>In spite of the success of fluorescence microscopes (such as stimulated emission depletion microscopy, stochastic optical reconstruction microscopy and photoactivated localization microscopy) in biomedical field, which have realized nanometer scale imaging resolution and promoted the great development of bio-medicine, the super-resolution imaging method for non-fluorescent sample is still scarce, and the resolution still has a big gap to nanometer scale. Among existing methods, structured illumination microscopy, PSF engineering, super-oscillatory lens and microsphere assisted nanoscopy are more mature and widely used. However, limited by the theory itself or engineering practice, the resolutions of these methods are hard to exceed 50 nm, which limits their applications in many fields. Enlightened by synthetic aperture technique, researchers have proposed spatial frequency shift super-resolution microscopy through shifting and combining the spatial frequency spectrum of imaging target, which is a promising super-resolution imaging scheme, for its resolution limit can be broken through continually. Currently, owing to the limitation of the refractive index of optical material, the wavelength of illumination evanescent wave is hard to shorten when this wave is generated at prism surface via total internal reflection, which determines the highest resolution of this spatial frequency shift super-resolution imaging system. Another deficiency of this scheme is the difference in imaging resolution among different directions, for the image has the highest resolution only in the direction along the wave vector of illumination evanescent wave; while, the image has the lowest resolution in the direction perpendicular to the wave vector, which is the same as that obtained by far-field illumination.</sec><sec>In order to solve the above thorny questions, a new model of generating the evanescent wave is proposed, which can generates an omnidirectional evanescent wave with arbitrary wavelength based on the phase modulation of nano-structure, and solve the both problem in imaging system at the same time. To verify the our scheme, we set up a complete simulation model for spatial frequency shift imaging scheme, which includes three parts: the generation of evanescent wave and the interaction of the evanescent wave with the nano-structures at imaging target, which can be simulated with FDTD algorithm; the propagation of light field from near-field to far-field region, from the sample surface to the focal plane of objective lens, which can be calculated with angular spectrum theory; the propagation of light field from the focal place to the image plane, which can be worked out with Chirp-Z transform.</sec><sec>Firstly, with this complete simulation model, we compare the resolution of microscopy illuminated by evanescent wave with that by propagating wave. The experimental results verify the super-resolution imaging ability of evanescent wave illumination and the influence of prism refractive index. The higher the refractive index, the shorter the wavelength of evanescent wave is and the higher the resolution of spatial frequency shift imaging system. Secondly, we demonstrate the resolution difference in a series of directions with a three-bar imaging target rotated to different directions. The result shows that the highest imaging resolution occurs in the direction of illumination evanescent wave vector, and the lowest resolution appears in the direction perpendicular to the wave vector. Finally, we simulate the evanescent wave generated by nano-strcuture and demonstrate its properties of wavelength and vector direction. When applied to near-field illumination super-resolution imaging, the omnidirectional evanescent wave solves the both problems in the model of total internal reflection from the prism surface.</sec><sec>Therefore, the advantages of our scheme are higher imaging resolution and faster imaging speed, no need for multi-direction and multiple imaging, and also image post-processing. In this study, a new spatial frequency shift super-resolution imaging method is proposed, which lays a theoretical foundation for its applications.</sec>

DEVELOPING OF A PORTABLE MICROWAVE CONVECTIVE DRYING PLANT FOR GRAIN STORED IN BULK

The data of the analysis of the application of electrophysical influences are presented and the choice of using a microwave field for the intensification of heat and mass transfer is justified; the results of a numerical experiment on the propagation of a microwave field and dissipated power in a dense grain layer at different material humidity when microwave energy is supplied through slit radiators combined with the duct of a ventilation installation. The development of combined grain drying modes in a dense stationary layer requires taking into account the maximum levels of permissible heating and the pattern of propagation of thermal fields during exposure. (Research purpose) The research purpose is developing the design of a portable ultra-high-frequency convective installation for drying grain stored in bulk. (Materials and methods) Presented a model of a portable installation for combined ultrahigh-frequency convective processing. A model of a waveguide-emitter was given for numerical simulation. (Results and discussion) A numerical experiment was conducted to determine the propagation of the microwave field in a layer of wheat of different humidity. (Conclusions) It was revealed that the results of modeling the distribution of the microwave field intensity in the grain mass can be used to develop modes of combined grain drying, taking into account the peculiarities of the propagation of thermal fields, power dissipation and the operation of field sources. It has been shown that as an intensifying factor of heat and mass transfer processes for a stationary grain layer, it is advisable to use a microwave field in a pulsed mode of operation combined with active ventilation. It was established that in order to influence the grain layer, it is necessary to use a microwave field with a frequency of 915 Megahertz, however, the absence of commercially available microwave field sources with a power of 200-1000 watts with air cooling limits this possibility. It was determined that the use of sources operating at a frequency of 2.45 Gigahertz as a microwave field is possible taking into account the development of pulsed modes of microwave field supply. It was stated that the use of an air duct with slit radiators allows for the supply of microwave energy to the required level in the height of the treated layer.

Self-healing of holographically generated moiré lattice wave fields

Self-healing in optics generally refers to the ability to reconstruct itself and restore the original state after encountering obstacles in the propagation of the light field. In this research, we observe the processes of the wave fields from perfect to defect in front of the focal plane of the 4f system, finally returning to an intact situation after the plane. According to simulations and experimental results, there is a minimum self-healing distance for the moiré lattice field that positively associates with the radius of the defect (obstacle) in the nondiffracting transmission range. Furthermore, it is observed that the defect self-healing is a process of “repairing the center and then repairing the edges.” These findings can be applied in areas such as optical imaging, capture, and information processing.

Evolution of extreme events in chaotic light-injected semiconductor lasers

<sec>Rare ultrahigh pulses, classified as rogue waves (RWs), are inevitable and catastrophic in many different systems. Considering the damage they may produce, it is meaningful to understand the formation mechanism of these pulses and, if possible, control them. However, the rarity of RW and the difficulty in implementing the experiment are major limitations to understanding their formation. In 2007, Solli et al. (Solli D R, Ropers C, Koonath P, Jalali B <ext-link ext-link-type="uri" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.nature.com/articles/nature06402">2007 <i>Nature</i> <b>450</b> 1054</ext-link>) introduced the concept of optical RW, i.e. extreme event (EE) by comparing the appearance of oceanic RWs with the propagation of light fields in optical fibers. After that, the research of EEs entered into a flourishing period and different optical systems were proposed to analyze the generation and origin of EEs. Linear system is one of the most widely studied EE systems, such as linear light propagation in glass fibers, random media, and linear interference models. In addition to the linear systems mentioned above, efforts have also been made to produce nonlinear systems of EEs, such as microstructure fibers and tapered gradient exponential nonlinear fibers. In these nonlinear systems, the formation mechanism of EE is studied by using the nonlinear Schrödinger equation. Recently, the EEs in semiconductor laser systems have received a great deal of attention. On the one hand, semiconductor lasers with rich dynamic properties provide a cheap and controllable platform for understanding and predicting EE. The behavior of EE, on the other hand, is a powerful tool for understanding the fundamental mechanism of different laser systems.</sec><sec>In this work, based on the EEs generated in a semiconductor laser with phase-conjugate optical feedback (the master laser, ML), we inject its output into another free-running semiconductor laser (the slave laser, SL) and discuss the evolution of EEs in the system by numerical simulation. Herein, we analyze the influence of injection parameters on EEs through the two-dimensional maps of the relative number of EEs in the injection-parameter space. It can be concluded that in an area of high correlation, the relative number of EEs in SL tends to be a stationary value close to that in ML, while it may be enhanced in some weakly correlated regions. The results demonstrate the possibility of controlling EEs by optical injection, which is beneficial to optimizing the performance of chaotic laser systems or expanding their application scope.</sec>

An Optically Transparent Hybrid Mechanism Metasurface for Wideband, Wide-Angle and Omnidirectional Scattering Suppression

Metasurface provides an efficient method to regulate wave propagation in multiphysics fields ranging from light waves, electromagnetic (EM) waves, and acoustic waves. Considering the versatile demands in practical scenarios, the essential challenge is to design the metasurface with spectral compatibility to satisfy the various applications. Here, we proposed an optically transparent hybrid mechanism metasurface (HMM) incorporating absorption, polarization conversion, and phase cancellation mechanisms for wideband, wide-angle, and omnidirectional scattering suppression performance. The unit cell integrates absorption and polarization conversion capabilities by etching the indium tin oxide (ITO) film into the specific structure, exhibiting wideband ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7.44-31.31$ </tex-math></inline-formula> GHz), wide-angle ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\!&lt; 45^{\circ }$ </tex-math></inline-formula> ), high-efficiency ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\!\ge 90$ </tex-math></inline-formula> %), and omnidirectional co-polarized scattering suppression performance. Moreover, the phase cancellation mechanism is implemented by distributing the unit cell and its mirror structure in the chessboard configuration, which provides cross-polarized reflection reduction capability for the HMM. Therefore, the HMM achieves a significant total radar cross section (RCS) reduction by integrating multiple scattering suppression mechanisms. Eventually, the simulated and measured results indicate that the proposed HMM can realize more than 10 dB total monostatic and bistatic RCS reduction within 7.49-32.23 and 7.46-30.55 GHz, respectively. In addition, good specular and omnidirectional RCS reduction capabilities are also obtained. Furthermore, the HMM also presents good optical transparency, which is attributed to the high transmittance of the polyethylene terephthalate (PET) substrates and the ITO films. The proposed strategy has potential application in the multifunctional stealth design of stealth platforms.

ХВИЛІ ЗСУВУ В ШАРУВАТО-ПЕРІОДИЧНІЙ СТРУКТУРІ «П'ЄЗОЕЛЕКТРИК - ЩІЛИНА»

A large number of scientific works are devoted to the problems of propagation of waves of different physical nature in periodic and heterogeneous media. The main problem considered in the article was the study of the shear wave in the layered-periodic structure "piezoelectric - gap". The statement is given and the problem of the propagation of volumetric acoustoelectric elastic shear waves in a regularly layered piezoelectric-slit medium is solved. Dispersion relations were obtained, which allow to investigate the possibility of propagation of wave fields with an arbitrary geometry of the period of the structure. A comparison of the spectra of the dispersion curves for volumetric acoustoelectric waves in a regularly layered space was carried out. The obtained dispersion relations were also analyzed numerically, and the results are presented in the form of graphs. Graphs of the limits of the boundaries of the transmission zones for various types of geometry of the generating layer package are given. As a result of numerical experiments, the possibility of the existence of transmission zones for bulk acoustic-electric waves in regularly layered media of the "piezoelectric - slot" type was established.

Effect of T‐Stress on Crack‐Tip Stress Field and Crack Propagation of Concrete

In order to predict the fracture toughness and propagation of the mixed mode fracture of concrete, the modified MTS (maximum tangential stress) criterion combined with T‐stress was presented. The modified MTS criterion uses a two‐parameter model (stress intensity factor K and T‐stress) to describe the concrete’s fracture. Through calculation, it is found that T‐stress can affect the maximum tangential stress, especially when T‐stress is negative. T‐stress is not taken into account in the traditional MTS criterion, which will lead to errors in calculating the maximum circumferential stress. The result of the specimen is not consistent with the predicted result of the traditional MTS. The modified criterion can provide accurate predictions for the experimental results. This provides a basis for the simulation of concrete’s fracture.

Analysis of Field Propagation inside A Waveguide Diplexer using Cavity Model Analysis

This paper presents a numerical analysis of field propagation inside a waveguide diplexer network. To do the analysis the diplexer network has been modeled using multiple cavities and then solved using a method of moments. Field propagation inside the network has been demonstrated in terms of aperture field distributions at various transverse planes of the network at the two-channel frequencies and a stopband frequency. To validate the numerical analysis, the frequency responses of the diplexer have been compared with literature available data.

Spatial Radiation Field Distribution of Underwater VLF Two-Element Antenna Array

In this communication, we analyze the field distributions of underwater very-low-frequency (VLF) two-element array composed of two symmetrical antennas. This analysis is carried out with the improved parallel total-field scattered-field source (TSS) finite-difference time-domain (FDTD) method with sea–air boundary field value conversion and thin-wire algorithm. We specifically analyze the field distribution in the range close to the antenna array in seawater. Furthermore, we also study the field propagation law in air propagating across the air–sea interface.

Physics-Driven Deep Learning Inversion for Direct Current Resistivity Survey Data

The direct-current (DC) resistivity method is a commonly used geophysical technique for surveying adverse geological conditions. The resistivity model can be reconstructed from data by inversion, which is an important step in geophysical surveys. However, the inversion problem is a serious one that can easily lead to incorrect results. Deep learning (DL) provides new avenues for solving inverse problems, and these methods have been widely studied. Currently, most DL inversion methods for resistivity are purely data-driven and depend heavily on labels (real resistivity models). However, real resistivity models are difficult to obtain through field surveys. As an inversion network may not be effectively trained without labels, we built an unsupervised learning resistivity inversion scheme based on the physical law of electric field propagation. First, a forward modeling process was embedded into the network training to convert the predicted resistivity model to predicted data, and form a data misfit with the observation data. Unsupervised training independent of labels was realized using the data misfit as a loss function. Moreover, a dynamic smoothing constraint was imposed on the loss function to alleviate the ill-posed inverse problem. Finally, a transfer learning scheme was employed to adapt the network trained with simulated data to field data. Numerical simulations and field tests showed that the proposed method can accurately locate and depict geological targets.

Development of models of the electromagnetic environment in buildings and urbanized areas

A set of measures and means to control the electromagnetic situation of the environment in the territories of urban development, in buildings and individual premises has been substantiated and developed. The simulation tools show the ability to rationalize the parameters of overhead lines with voltages of 220 kV and below, which will reduce the electromagnetic load in the territories. Modeling the propagation of fields from underground high-voltage lines has established that the values of magnetic fields compared to overhead lines are lower up to 30 times. Models of propagation of electromagnetic fields of very high and ultrahigh frequency were built. Sources of electromagnetic fields of non-production origin in industrial buildings have been investigated. Uncompensated currents in power networks with nonlinear electric consumers generate magnetic fields by induction of 0.35−1.20 μT, which exceeds the maximum permissible levels of operation of computer equipment. Leakage currents on grounded metal structures generate magnetic fields with 1.52−6.75 μT. Simulation of the propagation of electric and magnetic fields of components of personal computers of controlled ranges according to the MPRII standard was carried out. Models of propagation of the magnetic field of industrial frequency around electric motors and generators with their cross sections were built. On the basis of such models, design schemes for placing equipment in production areas are selected or places of safe stay and movement of personnel are selected. The expediency of using shielding to reduce field levels to safe values due to coating surfaces with liquid protective mixtures was shown. Metal-containing composition based on water-dispersion paint makes it possible to reduce the level of magnetic field of industrial frequency by 2.5−2.6 times, electric field by 1.6−1.7 times, electromagnetic field of industrial frequency – by 1.2−1.3 times.

Fully integrated optical sensor system with intensity interrogation

Introduction: Today sensor systems based on integrated photonics devices are the most important branch of embedded information and control systems for various functions. The output characteristics of a sensor system are significantly determined by the efficiency of the interrogator. The intensity interrogator based on a microring resonator can provide a high scanning rate and sensitivity that meets the requirements of a wide range of applications. Purpose: To develop an effective sensor system composed of a refractometric sensor and an interrogator located on the same photonic integrated circuit for marker-free determination of the concentration of substances in liquids. Methods: We use the numerical simulation of electromagnetic field propagation in a waveguide system (integrated silicon waveguides on a silicon dioxide substrate) in the research. The simulation has been carried out using the Ansys Lumerical environment, the FDTD (Finite Difference Time Domain) solver. The parameters of the microring resonators were optimized to obtain the coupling coefficients between the waveguides, providing the operation in the critical coupling mode. Results: We propose the concept of a fully integrated photonic sensor system based on micro-ring add-drop resonators. A sensor based on microring resonators has been developed, which consists of two half-rings with a radius of 18 μm, connected by sections of straight waveguides 3 μm long. An interrogator represented by a microring resonator with a radius of 10 µm has been developed. According to simulation results with a broadband source, the achieved sensor sensitivity was 110 nm per refractive index change, or 1350 dB per refractive index change. We propose a technique for choosing the optimal characteristics of the sensor and interrogator targeted to improve the complete system efficiency. Practical relevance: Sensor systems based on photonic integrated circuits can meet the demand for devices characterized by low power consumption, small size, immunity to electromagnetic interference and low cost.

Probing the optical near-field of plasmonic nano structure using scanning thermal microscopy

Scanning thermal microscopy (SThM) enables to obtain thermal characteristic information such as temperature and thermal conductivity from the signals obtained by scanning a thermometer probe over a sample surface. Particularly, the precise control of the thermometer probe makes it possible to study near-field radiative heat transfer by measuring the near-field thermal energy, which implies that when light is used as a local heat source, photothermal energy can be detected from the optical near-field by approaching the probe in the near-field region. In this study, SThM is applied to generate sub-wavelength near-field optical image in the plasmonic grating coupler. Herein, by controlling the surface plasmon polariton generation, we show that the dominant component of SThM signal is from the optical response rather than the thermal response. The obtained near-field optical images have a spatial resolution of 40 nm and signal to noise ratio of up to 19.8. In addition, field propagation images in the Z-direction can be visualised with the precise control of the distance between the thermometer probe and the sample

Distance and Efficiency Enhancement With Aspherical Retroreflectors for Resonant Beam SWIPT

The resonant beam system (RBS) with double spherical retroreflectors presents a potential mobile simultaneous wireless information and power transfer (SWIPT) technology without any tracking control. However, the movement distance and performance are limited due to the effect of spherical aberration. To improve mobility performance in RBS, including movement distance and output power, we adopt an aspherical lens as the focusing mirror in a retroreflector. By shifting the beam phase distribution, the aspherical lens focuses all passing beams, particularly edge beams, on the focal mirror, enhancing energy concentration in the resonant cavity. The beam field propagation through cat’s-eye retroreflectors, gain medium, and air is studied for analyzing the transfer efficiency and output power, and we demonstrate that the axial movement distance in the aspherical resonator is about 7 m, which is more than twice as far away as the spherical resonator. Within a field of view of 3° at a distance of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1~\rm {m}$ </tex-math></inline-formula> , the output power of the aspherical resonator is greater than that of the spherical resonator with the same movement angle, up to two times. The maximum output electric power and spectral efficiency are approximately <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4~\rm {W}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$12~\rm {bps/Hz}$ </tex-math></inline-formula> , respectively.

Massively parallelized interpolated factored Green function method

This paper presents the first parallel implementation of the novel “Interpolated Factored Green Function” (IFGF) method introduced recently for the accelerated evaluation of discrete integral operators arising in wave scattering and other areas (Bauinger and Bruno, Jour. Computat. Phys., 2021). On the basis of the hierarchical IFGF interpolation strategy, the proposed (hybrid MPI-OpenMP) parallel implementation results in efficient data communication, and it scales up to large numbers of cores—without any hard limitations on the number of cores efficiently employed. Moreover, on any given number of cores, the proposed parallel approach preserves the O(Nlog⁡N) computing cost inherent in the sequential version of the IFGF algorithm. Unlike other approaches, the IFGF method does not utilize the Fast Fourier Transform (FFT), and it is thus better suited for efficient parallelization in distributed-memory computer systems. In particular, the IFGF method relies on a “peer-to-peer” strategy wherein, at every level, field propagation is directly enacted via “exchanges” between “peer” polynomials of constant degree, without data accumulation in large-scale “telephone-central” mathematical constructs such as those used in the Fast Multipole Method (FMM) and pure FFT-based approaches. A variety of numerical results presented in this paper illustrate the character of the proposed parallel algorithm, in particular demonstrating scaling from 1 to all 1,680 cores available in the High Performance Computing cluster used, and for problems of up to 4,096 wavelengths in acoustic size.

Consistency between causality and complementarity guaranteed by the Robertson inequality in quantum field theory

It has long been debated whether gravity should be quantized or not. Recently, the authors in [Sci. Rep. 6, 22777 (2016); Proc. Natl. Acad. Sci. U.S.A. 106, 3035 (2009)] discussed the inconsistency between causality and complementarity in a Gedankenexperiment involving the quantum superposition of massive/ charged bodies, and Belenchia et al. [Phys. Rev. D 98, 126009 (2018); Int. J. Mod. Phys. D 28, 1943001 (2019)] resolved the inconsistency by requiring the quantum radiation and vacuum fluctuations of gravitational/electromagnetic field. Stimulated by their works, we reanalyze the consistency between the two physical properties, causality and complementarity, according to the quantum field theory. In this analysis, we consider a Gedankenexperiment inspired by [Sci. Rep. 6, 22777 (2016); Proc. Natl. Acad. Sci. U.S.A. 106, 3035 (2009); Phys. Rev. D 98, 126009 (2018); Int. J. Mod. Phys. D 28, 1943001 (2019)], in which two charged particles coupled with a photon field are in a superposition of two trajectories. First, we observe that causality is satisfied by the retarded propagation of the photon field. Next, by introducing an inequality between visibility and which-path information, we show that the quantum radiation and vacuum fluctuations of the photon field ensure complementarity. We further find that the Robertson inequality associated with the photon field leads to the consistency between causality and complementarity in our Gedankenexperiment. Finally, we mention that a similar feature appears in the quantum field of gravity.