Full Phase Research Articles

A shared-aperture transmissive/reflective bi-functional metasurface for both transmitarray and reflectarray

In this paper, a shared-aperture transmissive/reflective bi-functional metasurface is proposed. On metasurfaces, antisymmetric dipole pairs as transmissive elements and symmetric dipole pairs as reflective elements are interleaved in orthogonal polarization. By utilizing Huygens’ resonance, the metasurface can achieve near full phase coverage for orthogonally polarized transmitted and reflected wave. Then the bi-functional metasurface is used for the design of transmitarray (TA)/reflectarray (RA) bi-functional antenna. The measured results show that, for TA, the maximum gain is 30.26 dBi with antenna efficiency of 45.6 % and the 3-dB gain bandwidth is 26.3–29.3 GHz (10.79 %), and for RA, the maximum gain is 30.29 dBi with antenna efficiency of 45.7 % and the 3-dB gain bandwidth entirely covers the frequency region of 26–30 GHz. The bi-functional metasurface has important applications in the field of antenna engineering.

The dynamic nature of percolation on networks with triadic interactions

Percolation establishes the connectivity of complex networks and is one of the most fundamental critical phenomena for the study of complex systems. On simple networks, percolation displays a second-order phase transition; on multiplex networks, the percolation transition can become discontinuous. However, little is known about percolation in networks with higher-order interactions. Here, we show that percolation can be turned into a fully fledged dynamical process when higher-order interactions are taken into account. By introducing signed triadic interactions, in which a node can regulate the interactions between two other nodes, we define triadic percolation. We uncover that in this paradigmatic model the connectivity of the network changes in time and that the order parameter undergoes a period doubling and a route to chaos. We provide a general theory for triadic percolation which accurately predicts the full phase diagram on random graphs as confirmed by extensive numerical simulations. We find that triadic percolation on real network topologies reveals a similar phenomenology. These results radically change our understanding of percolation and may be used to study complex systems in which the functional connectivity is changing in time dynamically and in a non-trivial way, such as in neural and climate networks.

A framework to measure readiness and barriers for the implementation of Industry 4.0: A case approach

Large businesses perceive the vital usefulness of Industry 4.0. They recognize how beneficial its implementation is to reinforce business competitiveness and to conserve, or even better, to increase their market share. Hence, top business management has embraced the challenge of the time: to evaluate the current level of digitization with the objective of proceeding to a full digitization phase in the future. With this concern, this paper proposes a framework to assist industries in promoting Industry 4.0 through two phases. In the initial phase, the case company’s level of readiness is evaluated, and in the second phase, the barriers that exist within the implementation of Industry 4.0 (based on the company’s readiness, obtained from the previous phase) are analyzed. Both phases have been carried out at a Danish case industry which is a third-tier supplier of anti-noise shims and back plates for manufacturers of disc brake linings. In the first phase, the assessment of readiness for Industry 4.0 demonstrates that the case industry is not fully ready; instead, they reside in the position of Industry 3.5 (in the middle of 3.0 and 4.0 revolutions). The limiting barriers to change for Industry 4.0 implementation are identified during the systematic literature review and analyzed using the DEMATEL method based on the industrial decision-makers’ responses in the second phase. Moreover, the analysis demonstrates the most influential barrier category is the policy & organization category. The barrier “leadership” is considered the greater influencer of all since it responds in some way to almost all 21 barriers. Thus, leadership is the most significant barrier a company must overcome to adopt the Industry 4.0 concept. In addition, firms are challenged by the organizational changes that the adoption of Industry 4.0 will bring, and the tool of organizational change management will be handy.

Study of Types and Production of Trap Net Fishery Fish based on Moon Phase in the Waters of Segeri District, Pangkep Regency, South Sulawesi Indonesian

The research was carried out in October-November 2020 in the waters of the Pangkep Regency. The data collected consisted of primary and secondary data, using direct observation in the field. Tidal observations were carried out in every moon phase for 2 x 24 hours. I collected data on the type and number of catches in each month’s phase. Tidal analysis using the criminal method and descriptive analysis of the types and quantities of trap net fish production (kg) and (Rp). The full moon phase is the highest tide at 185 cm and the lowest at 42 cm. The average sea level (mean sea level) is 113.5 cm. Types of trap net catch based on the moon phase in the waters of Sergei District, Pangkep Regency, identified 13 types of catches. The highest amount of fish production was obtained by the full moon phase of 100 kg, followed by the 80 kg dead moon phase, 95 kg early quarter moon, and 65 kg final quarter moon phase.

Tightly Coupled Huygens Element-Based Conformal Transmitarray for E-Band Airborne Communication Systems

In this article, a wideband conformal transmitarray employing dual-layer tightly coupled Huygens elements is proposed at E-band. The element consists of five pairs of partly overlapped metallic strips with different lengths printed on two sides of a dielectric substrate. It can support tightly coupled Huygens resonances with a high transmission efficiency and a nearly full phase coverage in a wide bandwidth from 71 to 87 GHz. Equivalent circuit models are created to analyze the tightly coupled Huygens element, which has good agreement with that from full-wave simulations. In order to validate the proposed element, a cylindrically conformal transmitarray at 78 GHz is designed, fabricated, and measured. Good agreement between the measured and simulated results has been obtained, showing a peak realized gain of 26.6 dBi with an aperture efficiency of 37.2% from measurement. A measured 3 dB gain bandwidth of 20.4% is achieved from 71 to 87 GHz, fully covering the E-band spectrum.

Retrospective and Prospective Analysis on “Sexting”: Indicators of Productivity, Dispersion, and Content (2009–2019)

In the last decade, research on “sexting” has undergone an exponential increase, giving rise to the publication of numerous studies clarifying its meaning, offering information of educational value, and favoring a good use of technology to prevent problems caused by this exchange of sexual information. The aim of this article was to analyze the production, performance, impact, and content of scientific articles evaluating the “sexting” thesaurus (title, abstract, and/or keywords) between 2009 and September 2019. Articles were sourced from two internationally recognized databases: Scopus and Web of Science. A scientometric study was then carried out on a sample of 641 articles that met the established inclusion criteria. The main findings indicate that “sexting” is a very recent research focus, but one in full growth phase, with scientific production related to the topic likely to double over the next few years. Although “sexting” has been researched worldwide, the scientific production of the US and American authors is the most notable. There were also some differences between the Scopus and Web of Science databases, mainly in the volume of production and the trend. However, the studies do show a common research line, “cyberbullying,” and a common target population: adolescents. Therefore, the content analysis reveals that research on “sexting” is mostly carried out with adolescents and takes into consideration other themes such as cyberbullying, dating violence, and sexuality.

Inverse-designed single-phase elastic metasurfaces for underwater acoustic vortex beams

During the past decade, the passive metasurfaces enabling vortex beams carrying orbital angular momentum have drawn great interest in the fields of electromagnetic and acoustic wave. In the underwater environment, however, the elastic metasurface with a certain bandwidth is more difficult to be realized due to the strong fluid-solid interaction and rigorous impedance matching. To overcome this challenge, an inverse-design strategy is proposed to systematically construct a single-phase underwater metasurface for converting the incident plane waves into vortex beams on demand. All topology-optimized metasurface elements, possessing both the positive/negative effective dynamic properties for the full phase control, can support the desired phase modulation and high transmission. We numerically and experimentally demonstrate the acoustic functionality of converting the plane waves in free space to the first-order vortex modes. The present passive single-phase metasurface by inverse design may offer opportunities for underwater acoustic communication.

Alfvén eigenmode stability in a JET afterglow deuterium plasma and projections to deuterium–tritium plasmas

The performance of fusion devices relies strongly on the good confinement of energetic particles (EPs). Therefore, the investigation of EP transport by magnetohydrodynamic instabilities is one of the key aspects in the development of plasma scenarios. Alfvénic instabilities in particular can lead to significant losses of alpha particles that are essential for plasma self-heating. A so-called afterglow scheme has been developed to study the destabilization of Alfvén eigenmodes (AEs) by alpha particles and associated EP transport in the JET tokamak. In this work, the linear stability of AEs is discussed for the partial afterglow phase in a JET deuterium plasma discharge and for the full afterglow phase in a projected deuterium–tritium (DT) plasma. Thanks to recent upgrades in the tokamak transport code TRANSP, one can account for the contributions of different EP species to mode stability. Analysis of deuterium plasmas shows that AE growth rates are extremely sensitive to the energy and distribution of fast ions. An increase in fast ion energy can lead to more unstable AEs. In the afterglow phase of projected DT plasmas, it is EPs that mostly drive the AEs. However, the drive by alpha particles is comparable to that by beam ions and their contribution to the net growth rate might be hard to separate. According to the discussed projections, the destabilization of AEs might be ineffective because the background plasma damping significantly exceeds the EP drive. In this case, the development of an alternative plasma scenario that allows us to overcome such damping would be required in future experiments.

Revealing the embedded phase in single-pixel quantum ghost imaging

Single-pixel quantum ghost imaging involves the exploitation of non-local photon spatial correlations to image objects with light that has not interacted with them and, using intelligent spatial scanning with projective masks, reduces detection to a single pixel. Despite many applications, extension to complex amplitude objects remains challenging. Here, we reveal that the necessary interference for phase retrieval is naturally embedded in the correlation measurements formed from traditional projective masks in bi-photon quantum ghost imaging. Using this, we develop a simple approach to obtain the full phase and amplitude information of complex objects. We demonstrate straightforward reconstruction without ambiguity using objects exhibiting spatially varying structures from phase steps to gradients as well as complex amplitudes. This technique could be an important step toward imaging the phase of light-sensitive structures in biological matter.

Black and gray box learning of amplitude equations: Application to phase field systems.

We present a data-driven approach to learning surrogate models for amplitude equationsand illustrate its application to interfacial dynamics of phase field systems. In particular, we demonstrate learning effective partial differential equationsdescribing the evolution of phase field interfaces from full phase field data. We illustrate this on a model phase field system, where analytical approximate equationsfor the dynamics of the phase field interface (a higher-order eikonal equationand its approximation, the Kardar-Parisi-Zhang equation) are known. For this system, we discuss data-driven approaches for the identification of equationsthat accurately describe the front interface dynamics. When the analytical approximate models mentioned above become inaccurate, as we move beyond the region of validity of the underlying assumptions, the data-driven equationsoutperform them. In these regimes, going beyond black box identification, we explore different approaches to learning data-driven corrections to the analytically approximate models, leading to effective gray box partial differential equations.

A unified picture of medium-induced radiation

We revisit the picture of jets propagating in the quark-gluon plasma. In addition to vacuum radiation, partons scatter on the medium constituents resulting in induced emissions. Analytical approaches to including these interactions have traditionally dealt separately with multiple, soft, or rare, hard scatterings. A full description has so far only been available using numerical methods. We achieve full analytical control of the relevant scales and map out the dominant physical processes in the full phase space. To this aim, we extend existing expansion schemes for the medium-induced spectrum to the Bethe-Heitler regime. This covers the whole phase space from early to late times, and from hard splittings to emissions below the thermal scale. Based on the separation of scales, a space-time picture naturally emerges: at early times, induced emissions start to build from rare scatterings with the medium. At a later stage, induced emissions due to multiple soft scatterings result in a turbulent cascade that rapidly degrades energy down to, and including, the Bethe-Heitler regime. We quantify the impact of such an improved picture, compared to the current state-of-the-art factorization that includes only soft scatterings, by both analytical and numerical methods for the medium-induced energy distribution function. Our work serves to improve our understanding of jet quenching from small to large systems and for future upgrades of Monte Carlo generators.

Magnetic phase diagram and possible Kitaev-like behavior of the honeycomb-lattice antimonate Na3Co2SbO6

Recent theoretical studies have suggested that Kitaev physics and such effects as formation of a mysterious spin-liquid state can be expected not only in RuCl3 and iridates, but also in conventional $3d$ transition metal compounds. Using DC and AC magnetometry, thermodynamic and $^{23}$Na nuclear magnetic resonance measurements (NMR) we studied such a candidate material Na3Co2SbO6. A full phase diagram of Na3Co2SbO6 in a wide range of magnetic fields and temperatures is presented. The results demonstrate transformation of the antiferromagnetic structure under the external magnetic field, gradual development of the saturation phase, as well as evidence of gapped behavior in certain parts of the phase diagram

Engineering of efficient visible light photocatalysts: Ti1–x+yCuxLayO2 (x = 0.03; y = 0, 0.005, 0.01) compositions

In dye-photocatalysis, widening the wavelengths absorption range of catalysts as well as aborting the recombination of the photoexcited charge carriers (electrons–holes pairs) are of paramount significance. In the current study, we report the photocatalytic characteristics of four compositions composed of TiO2, Ti0.97Cu0.03O2, Ti0.965Cu0.03La0.005O2 and Ti0.96Cu0.03La0.01O2 powders for two harmful dyes (Congo red and methylene blue). The X-ray diffraction technique verified the configuration of mixed anatase and rutile phases in pure TiO2 and Ti0.97Cu0.03O2 powders while Ti0.965Cu0.03La0.005O2 and Ti0.96Cu0.03La0.01O2 powders possess anatase phase only. The changes of the band gap structure and dimensions of the unit cell volume of TiO2 confirm the substitution of Ti4+ sites by Cu2+ and La3+ ions. Remarkable widening of wavelengths absorption with formation of long absorption tails were found in TiO2 (3.13 eV) through insertion of La3+ plus Cu2+ ions. Ti0.965Cu0.03La0.005O2 and Ti0.96Cu0.03La0.01O2 samples exhibit a visible light band gap of 2.3 and 2.7 eV, respectively. Based on SEM images, incorporation of Cu2+ and La3+ ions influences the surface morphology of TiO2. The resulting Ti0.97Cu0.03O2, Ti0.965Cu0.03La0.005O2 and Ti0.96Cu0.03La0.01O2 powders present enhanced photocatalytic activity towards Congo red dye degradation compared to pure one under natural solar spectrum. The best Ti0.96Cu0.03La0.01O2 catalyst exhibits superior photocatalytic activity of 96% for 10 ppm CR dye in 20 min as well as above average photocatalytic efficiency of 63% for 30 ppm CR dye in 120 min. As well, it showed acceptable photodegradation activity of 52% for 30 ppm MB solution in 140 min of sunlight irradiation. The heightened photodegradation efficiency of Ti0.96Cu0.03La0.01O2 catalyst can be clarified in terms of higher charge carriers’ separation (Cu2+ + e– → Cu+, La3+ + e– → La2+), oxygen vacancies, full anatase phase structure as well as the wide range of visible light absorption.

Mechanisms of the preferential cleavage of Ti2AlNb-based alloy: The influence of grain size and local plasticity

An in-depth understanding on the preferential cleavage of the matrix B2 phase, with an ordered body-centered cubic (BCC) structure, is pivotal to improve the processability of Ti2AlNb-based alloys. This research employed in-situ micro tensile tests, multiscale microstructure characterizations, and crystal plasticity simulations to study the grain-size dependent cleavage of the alloy with a full B2 phase. The material was intentionally prepared with two grain sizes differing by order of magnitude, i.e., the millimeter-level coarse grain (CG) and the micron-level fine grain (FG). The experimental results showed that the cleavage of CGs always occurred on the {100} planes, even when the loading direction was much less favorable for the cleavage of these planes, whereas the cleavage of FGs took place on both {100} and {110} planes. The investigation demonstrated that the plastic deformation takes a critical role in selecting cleavage planes. Full-field crystal plasticity simulations demonstrated that, for the CGs, the plastic deformation associated with cleavage on {100} planes is less than that associated with cleavage on {110} planes, indicating a less plastic deformation-induced blunting effect with cleavage on {100} planes. For the FG material, however, the existence of plentiful grain boundaries (GBs) leads to significantly heterogeneous plastic deformation, local stress distribution deviating from the imposed global stress, and hot spots of stress and strain concentration at GB triple junctions. These local plasticity heterogeneities enable the possibility for cleavage on both the {100} and {110} planes.

Terahertz isotropic transmissive metasurfaces for generation of different wavefronts

Metasurfaces are highly advantageous in realizing the phase discontinuity of an electromagnetic wave. Aiming at manipulating electromagnetic wavefront in terahertz band, a subwavelength multilayer meta-atom is designed, and it is composed of gold mesh, gold disk, and polyimide. By varying the diameter of the central gold disk, eight meta-atoms are prepared to provide full phase modulation with phase increase of 45°. A series of transmissive metasurfaces consisting of these meta-atoms are designed with different arrays. They achieve generations of deflection, single-focusing, dual-focusing, and orbital angular momentum with and . It is noteworthy that metasurfaces assembled by these isotropic meta-atoms are polarization-insensitive. Our models are numerically verified, and all results are consistent with theoretical predictions. Different from reflective metasurfaces that sometimes encounter feeding blockage, transmissive metasurfaces are feasible for the realization of a more compact terahertz system.

ReneSANCe event generator for high-precision e + e − physics

We present a new version of the Monte Carlo event generator ReneSANCe. The generator takes into account complete one-loop electroweak (EW) corrections, higher order QED corrections in the leading logarithm (LL) approximation and some higher order EW corrections to processes at e + e − colliders with finite particle masses and arbitrary polarizations of initial and final particles. ReneSANCe can produce events in the full phase space and this option is available for a wide range of center-of-mass energies.

On‐Chip Metaline for Multiport Beam Splitting

AbstractWave shaping plays an important role in on‐chip signal processing. However, previously reported photonics elements exhibit limited control capabilities or require complex nanofabrication techniques. Here, an on‐chip metadevice is proposed for multiport beam splitting based on a 1D slots array on the silicon‐on‐insulator platform, which has the advantages of high efficiency, full 2π phase shift, and an easy design scheme. The proposed metadevice is experimentally demonstrated at 1550 nm, which shows different numbers of beam splits. This design provides a new solution for on‐chip beam splitting, which has great potential in wide applications such as signal processing, on‐chip laser modulation, on‐chip neural network, etc.

High-efficiency ultrathin metasurfaces with simultaneous control of complete phase, amplitude, and polarization.

Metasurfaces that can simultaneously manipulate both amplitude and phase have garnered interest and have promising applications owing to their strong beam-steering ability; however, achieving a high maximum transmission while covering the full phase shift remains challenging. This paper proposes a chiral-structured meta-atom composed of two external cross-polarized patches and an internal coupling structure. It enables the independent modulation of the phase, amplitude, and polarization at large incidence angles and ensures a high maximum transmission with a complete phase shift enabled by the two internal rotation structures. The transmission phase and amplitude can be independently controlled by adjusting the geometry and rotation angle of the meta-atoms. The performance and feasibility of the method were verified using an ultra-thin high-order Bessel beam generator sample with a thickness of 2 mm (about λ0/11 at 14 GHz). This design can meet arbitrary requirements for extreme beam steering and has broad application prospects in the fields of electromagnetism and photonics.

Impact of instrument and data characteristics in the interferometric reconstruction of the 21 cm power spectrum

ABSTRACT Combining the visibilities measured by an interferometer to form a cosmological power spectrum is a complicated process. In a delay-based analysis, the mapping between instrumental and cosmological space is not a one-to-one relation. Instead, neighbouring modes contribute to the power measured at one point, with their respective contributions encoded in the window functions. To better understand the power measured by an interferometer, we assess the impact of instrument characteristics and analysis choices on these window functions. Focusing on the Hydrogen Epoch of Reionization Array (HERA) as a case study, we find that long-baseline observations correspond to enhanced low-k tails of the window functions, which facilitate foreground leakage, whilst an informed choice of bandwidth and frequency taper can reduce said tails. With simple test cases and realistic simulations, we show that, apart from tracing mode mixing, the window functions help accurately reconstruct the power spectrum estimator of simulated visibilities. The window functions depend strongly on the beam chromaticity and less on its spatial structure – a Gaussian approximation, ignoring side lobes, is sufficient. Finally, we investigate the potential of asymmetric window functions, down-weighting the contribution of low-k power to avoid foreground leakage. The window functions presented here correspond to the latest HERA upper limits for the full Phase I data. They allow an accurate reconstruction of the power spectrum measured by the instrument and will be used in future analyses to confront theoretical models and data directly in cylindrical space.

Production of ultracold neutrons in a decelerating trap

This note proposes a new concept for the production of ultracold neutrons (UCNs) in a decelerating trap. UCNs are widely used in the physics of elementary particles and fundamental interactions, and can potentially be used in studies of condensed matter. However, most of these studies are limited by the available UCN densities and fluxes. One of the ways to increase them is to extract more neutrons from the full phase space of a source and better exploit peak fluxes in pulsed neutron sources, orders of magnitude larger than the mean values. For instance, at ESS, the pulsed flux will be a factor of ∼25 larger than the mean flux of ILL at nominal power. Here, a concept of UCN sources is proposed, which allows to implement this idea. We propose to produce very cold neutrons (VCNs) in converters located in a neutron source, extract and slow them down to UCNs by a decelerating magnetic or material trap. As shown in this paper, for both pulsed and continuous neutron sources, this method could provide a high conversion efficiency of VCNs to UCNs with low losses of density in the phase space. More detailed calculations and the proposals for concrete technical designs are going to be developed in future publications.