Relative Phase Research Articles

Ultra-broadband achromaticity of metalens with low-relative phase enabled by wide-band fusion

Metalenses have a high design degree of freedom in controlling the light field and excellent performance in chromatic aberration elimination. However, in designing ultra-broadband achromatic metalenses, integrating multiple types of unit structures is necessary to compensate for phase differences caused by different incident wavelengths. Here, we propose an ultra-broadband achromatic metalens composed only of a single type of square nano-pillar. which controls the entire operating band by utilizing three wide-band fusions, and have characteristics depending on the phase coverage and relative phase. In the operational range of 2–5 μm, the achromatic metalens demonstrates a maximum focal shift of 2.1 μm. The average focal shift is 0.98 %, the average NA value is 0.35, with an average relative phase of 0.77π. The average transmittance and focus efficiency are 94.17 % and 58.7 %, respectively. This broad-spectrum fusion design strategy simplifies manufacturing complexity while maintaining high focusing efficiency and transmittance levels throughout the entire operational bandwidth. This design approach can improve image resolution and quality by minimizing chromatic aberration.

Dynamics of U(1) gauged Q -balls in three spatial dimensions

We investigate the dynamics of U(1) gauged Q-balls using fully three-dimensional numerical simulations. We consider two different scenarios: first, the classical stability of gauged Q-balls with respect to generic three-dimensional perturbations, and second, the behavior of gauged Q-balls during head-on and off-axis collisions at relativistic velocities. With regard to stability, we find that there exist gauged Q-ball configurations which are classically stable in both logarithmic and polynomial scalar field models. With regard to relativistic collisions, we find that the dynamics can depend on many different parameters such as the collision velocity, relative phase, relative charge, and impact parameter of the colliding Q-balls. Published by the American Physical Society 2024

Long-range phase coherence and tunable second order φ0-Josephson effect in a Dirac semimetal 1T-PtTe2

Superconducting diode effects have recently attracted much attention for their potential applications in superconducting logic circuits. Several pathways have been proposed to give rise to non-reciprocal critical currents in various superconductors and Josephson junctions. In this work, we establish the presence of a large Josephson diode effect in a type-II Dirac semimetal 1T-PtTe2 facilitated by its helical spin-momentum locking and distinguish it from extrinsic geometric effects. The magnitude of the Josephson diode effect is shown to be directly correlated to the large second-harmonic component of the supercurrent. We denote such junctions, where the relative phase between the two harmonics can be tuned by a magnetic field, as ‘tunable second order φ0-junctions’. The direct correspondence between the second harmonic supercurrents and the diode effect in 1T-PtTe2 junctions at relatively low magnetic fields makes it an ideal platform to study the Josephson diode effect and Cooper quartet transport in Josephson junctions.

Improving Bulk and Interfacial Lithium Transport in Garnet-Type Solid Electrolytes through Microstructure Optimization for High-Performance All-Solid-State Batteries.

Garnet-type Li6.4La3Zr1.4Ta0.6O7 (LLZTO) is regarded as a highly competitive next-generation solid-state electrolyte for all-solid-state lithium batteries owing to reliable safety, a wide electrochemical operation window of 0-6 V versus Li+/Li, and a superior stability against Li metal. Nevertheless, insufficient interface contacts caused by pores, along with Li dendrite growth at these voids and grain boundary regions, have hindered their commercial application. Herein, we suggest a method to produce high-quality LLZTO using LiAlO2 (LAO) as a chemical additive that leads to an improved microstructure with larger grain size (∼25 μm), a high relative density (∼96%), lower porosity (∼3.7%), and continuous secondary phases in grain boundary regions. This improved structure results in (i) improved Li-ion conductivity and enhanced interfacial resistance between Li metal and LLZTO by a denser structure with fewer pores and (ii) suppression of Li dendrite penetration in the electrolyte by secondary phases in grain boundary regions.

3D coherent single shot lidar imaging beyond coherence length

Advancements in remote sensing and autonomous vehicle technologies made lidars equally important for unmanned objects alongside cameras. Therefore, precise 3D lidar imaging and point cloud generation have become important subjects. Although existing coherent lidar technologies provide precise imaging results, the spectral linewidth of the laser sources becomes a key limitation over long distances as it defines the maximum detection range. Here, we present long-distance 3D lidar imaging which removes the coherence length limitations and therefore the necessity of high-coherence laser sources. Mainly, we generate optical sidebands, by modulating a continuous wave (CW) laser source with multiple radio-frequency (RF) tones. Then, using our own post-processing and triangulation methods, we use the relative phase changes between the sidebands which are free from laser phase noise to determine the target distance. We prove that the multi-tone coherent Lidar technique can perform precise 3D imaging and point cloud generation of various targets at sub-10pW optical power reception and distances up to ∼12× beyond the coherence length of the CW laser employed in the lidar architecture. Overall, it is demonstrated that coherence length restriction is removed by the suggested method, which makes precise long-distance 3D lidar imaging possible, particularly for applications such as spacecraft and aerial coherent lidars.

Noise-Induced Quantum Synchronization and Entanglement in a Quantum Analogue of Huygens' Clock.

We propose a quantum analogue of the Huygens clock, where the phases of two spins synchronize through their interaction with a shared environment. This environment acts like the escapement mechanism in a mechanical clock, regulating the gear train and allowing discrete timing advances. In our model, the relative phases of the two spins synchronize via a mutually correlated environment. We demonstrate that several arguments can significantly reduce the cardinality of the allowed measurements for a system of qubits, thus simplifying the problem. We present a numerically efficient method to calculate the degree of quantumness in the correlations of the final density matrix, providing a tight upper bound for rank 3 and rank 4 density matrices. We suggest a potential realization of noise-induced synchronization between two nuclear spins coupled to a common ancilla undergoing dynamical decoupling.

Microfluidic Exploitation of Liquid Crystal Properties of Boron Nitride Nanotubes and Enhancing Neutron Shielding with Aligned Structure

Boron nitride nanotubes (BNNTs) are cylindrical nanostructures characterized by alternating boron and nitrogen atoms. Unlike carbon nanotubes (CNT), BNNTs are electrically insulating and exhibit high thermal stability and neutron shielding capabilities. Their unique tubular structure enables the formation of 1D arrays, which can achieve a nematic liquid crystal phase, ideal for fabricating high‐density structures. However, the widespread application of BNNTs has been hindered by challenges in purifying and dispersing high‐purity BNNTs. This study aims to exploit the liquid crystal properties of BNNTs by generating high‐purity BNNT dispersions through a series of dispersion and purification processes. Furthermore, this study utilizes microfluidics technology to encapsulate the BNNT dispersions. Using this approach, the transition of liquid crystal phases in relation to BNNT concentration is efficiently examined. This process results in the production of high‐density BNNT films characterized by pronounced anisotropy, which in turn provides significant thermal neutron shielding effects.

Determining the optimum number of cycles for calculating joint coordination and its variability during running at different speeds: A timeseries analysis

Understanding the intricacies of human movement coordination and variability during running is crucial to unraveling the dynamics of locomotion, identifying potential injury mechanisms and understanding skill development. Identification of minimum number of cycles for calculation of reliable coordination and its variability could help with better test organization and efficient assessment time. By adopting a cross-sectional study design, this study investigated the minimum required cycles for calculating hip-knee, hip-ankle and knee-ankle coordination and their variability using a continuous relative phase (CRP) method. Twenty-nine healthy adults ran on a treadmill at speeds of 9, 12.5, and 16 km.h−1 while 3D kinematic data of their lower limbs were recorded using 6 optoelectronic cameras. Using Intraclass Correlation Coefficient (ICC) analysis, reliability between CRP and its variability (CRPv) in different gait cycles (3, 5, 10, 20, 30) was assessed for each speed. A minimum of 10 cycles was required for CRP calculation across all speeds, whereas CRPv necessitated a minimum of 30 cycles for moderate to good reliability. While increasing the number of cycles improved ICC values for inter-joint CRP, the same trend was not consistently observed for CRPv, emphasizing the importance of separately assessing CRP and its variability metrics.

Mode locking mechanism in Fourier-domain mode-locked optoelectronic oscillators

Fourier-domain mode-locked (FDML) optoelectronic oscillators (OEOs) are regarded as a promising candidate to generate linearly chirped microwave waveforms (LCMWs) with large time-bandwidth products. Nevertheless, up to date, the mode locking mechanism in FDML-OEOs is still not clear enough. Here, a comprehensive theoretical analysis is made to reveal the mode locking mechanism in FDML-OEOs. In particular, the phase relationship among numerous oscillation modes under stable oscillation is obtained. In addition, the FDML oscillation process originated from either noise or single-mode oscillation and is numerically simulated based on the model. Therefore, the initial oscillation process is comprehensively analyzed in the time domain, the Fourier domain, and the fractional Fourier domain, which provides a deep insight into the FDML oscillation process. Finally, the initial oscillation process of a FDML-OEO is captured in the experiment. The corresponding analysis is carried out to reveal the real mode locking mechanism, where the experimental results fit in with the theoretical and numerical results. This work provides a new approach for in-depth analysis of FDML-OEOs.

Rhythm-based Temporal Expectations: Unique Contributions of Predictability and Periodicity.

Anticipating events and focusing attention accordingly are crucial for navigating our dynamic environment. Rhythmic patterns of sensory input offer valuable cues for temporal expectations and facilitate perceptual processing. Rhythm-based temporal expectations may rely on oscillatory entrainment, where neural activity and perceptual sensitivity synchronize with periodic stimuli. However, whether entrainment models can account for aperiodic predictable rhythms remains unclear. Our study aimed to delineate the distinct roles of predictability and periodicity in rhythm-based expectations. Participants performed a pitch-identification task preceded by periodic predictable, aperiodic predictable, or aperiodic unpredictable temporal sequences. By manipulating the temporal position of the target sound, we observed how auditory perceptual performance was modulated by the target position's relative phase relationship to the preceding sequences. Results revealed a significant performance advantage for predictable sequences, both periodic and aperiodic, compared with unpredictable ones. However, only the periodic sequence induced an entrained modulation pattern, with performance peaking in synchrony with the inherent sequence continuation. Event-related brain potentials corroborated these findings. The target-evoked P3b, possibly a neural marker of attention allocation, mirrored the behavioral performance patterns. This supports our hypothesis that temporal attention guided by rhythm-based expectations modulates perceptual performance. Furthermore, the predictive sequences were associated with enhanced target-preceding negativity (akin to the contingent negative variation), indicating enhanced target preparation. The periodic-specific modulation likely reflects more precise temporal expectations, potentially involving neural entrainment and/or more focused attention. Our findings suggest that predictability and periodicity influence perception through distinct mechanisms.

Standardized diagnosis of gastrointestinal tumors: an update regarding the situation in Germany.

To evaluate the current status of the diagnosis of gastrointestinal tumors in Germany by means of a survey of the oncological imaging working group of the German Radiological Society (DRG) with a focus on the CT protocols being used.Radiologists working in outpatient or inpatient care in Germany were invited. The survey was conducted between 10/2022 and 06/2023 using the SurveyMonkey web tool. Questions related to gastrointestinal cancer were asked with regard to the commonly used imaging modalities, body coverage, and contrast agent phases in CT as well as the use of oral or rectal contrast. The results of the survey were analyzed using descriptive statistics.Clear differences were identified regarding the acquired contrast phases in relation to the place of work - outpatient care, smaller hospitals, maximum care hospitals, or university hospitals. Variances were also recognized regarding oral and rectal contrast. Based on the results and international guidelines, proposals for CT protocols were derived.CT protocols in Germany show a heterogeneous picture regarding acquired contrast phases, as well as oral and rectal contrast for the staging of gastrointestinal cancer. Clear recommendations in the respective guidelines would aid in quality assurance and comparability between different centers. · The examination protocols for the staging of gastrointestinal tumors are heterogeneous in Germany.. · The application of oral and rectal contrast is handled differently at the various radiological centers.. · Standardization of imaging should be targeted.. · Gerwing M, Ristow I, Afat S et al. Standardized diagnosis of gastrointestinal tumors: an update regarding the situation in Germany. Fortschr Röntgenstr 2024; DOI 10.1055/a-2378-6451.

Decoding roughness perception in distributed haptic devices

Abstract The ability to render realistic texture perception using haptic devices has been consistently challenging. A key component of texture perception is roughness. When we touch surfaces, mechanoreceptors present under the skin are activated and the information is processed by the nervous system, enabling perception of roughness/smoothness. Several distributed haptic devices capable of producing localized skin stretch have been developed with the aim of rendering realistic roughness perception; however, current state-of-the-art devices rely on device fabrication and psychophysical experimentation to determine whether a device configuration will perform as desired. Predictive models can elucidate physical mechanisms, providing insight and a more effective design iteration process. Since existing models (1, 2) are derived from responses to normal stimuli only, they cannot predict the performance of laterally actuated devices which rely on frictional shear forces to produce localized skin stretch. They are also unable to predict the augmentation of roughness perception when the actuators are spatially dispersed across the contact patch or actuated with a relative phase difference (3). In this study, we have developed a model that can predict the perceived roughness for arbitrary external stimuli and validated it against psychophysical experimental results from different haptic devices reported in literature. The model elucidates two key mechanisms: 1) The variation in the change of strain across the contact patch can predict roughness perception with strong correlation 2) The inclusion of lateral shear forces is essential to correctly predict roughness perception. Using the model can accelerate device optimization by obviating the reliance on trial-and-error approaches.

Importance of tides and winds in influencing the nonstationary behaviour of coastal currents in offshore Singapore

Abstract. Coastal currents significantly impact port activities, coastal landform morphodynamics, and ecosystem functioning. It is therefore necessary to understand the physical characteristics and natural variability of these currents within coastal settings. Traditional methods, such as harmonic analysis, assume stationarity of tide-driven currents and may thus not be applicable to systems modulated by variable nontidal inputs and processes. Here we deployed eight tilt current meters in shallow (< 5 m) coral reef environments in southern Singapore. Tilt current meters were positioned around the reefs at the main compass bearings to analyse the spatiotemporal variability of coastal currents in the frequency domain for 1 year (March 2018 to March 2019). Tidal motions were the primary mechanism of current flow on reefs and account for between 14 % and 45 % of total variance across all sites, with diurnal currents having either a similar or greater proportion of energy compared to semidiurnal currents. The relationship between currents and wind stress was then investigated across various frequencies. There is high correlation at low frequencies during the northeast monsoon, when the Madden–Julian Oscillation (MJO) is more active, thus generating currents that propagate either in phase or ahead of the MJO. At diurnal frequencies, the interaction between P1 and K1 results in a semi-annual cycle where currents are stronger during the monsoon seasons. This interaction could help to explain the seasonal variation in correlation as well as the K1 amplitude, the latter of which could be further enhanced by the diurnal wind stress. The phase relationship between currents and wind stress is highly complex due to the variable bathymetry and could only be partially accounted for by the orientation of the coastlines relative to that of the wind. Given the importance of wind, we thus require longer time-series datasets to examine the role of atmospheric phenomena at greater timescales to improve our understanding of the variability of coastal currents.

Densification, deformation, and delamination during co‐sintering process of metal–ceramic laminates

AbstractToday, there is a high demand and increasing trend for multifunctional composite materials and components due to the combination of a wide range of favorable properties. However, undesired deformation leading to delamination, curvature, cracks, or even complete fracture frequently occurs during the co‐sintering process of metal–ceramic laminates (MCLs). To solve these issues, experimental work highly relies on the time‐consuming trial‐and‐error principle. This work aims to develop a thermo‐mechanical‐metallurgical model capable of predicting the densification, deformation, and delamination of MCLs during the co‐sintering process. It is found that the developed model successfully considers the inhomogeneous relative density distribution and phase transformation of the steel tape. In addition, a thin interlayer formed by a mixed slurry in the MCLs is modeled as cohesive elements to simulate the delamination process. The developed model is systematically validated by the experimental measurements and observations in terms of densification, deformation, and delamination during the co‐sintering process of the investigated laminate variants.

A novel strategy for water content analysis in (B12C4/B15C5/B18C6-[EMIm][NTf2])-LiNTf2 extraction system: Quantitative calculation and theoretical study

The metal ion extraction processis usually accompaniedby the removal of coordinated water molecules and the change of water content in the extraction phase. However, hierarchical methodologies on water researchare incredibly sparse, restricting a thorough knowledge of the extraction mechanism.It was clarified the diversity of water occurrence forms in the extraction phase and quantitative relationship between water, Li+ and crown ether based on the (B12C4/B15C5/B18C6-[EMIm][NTf2])-LiNTf2 solvent extraction system. While the complexation mechanism between hydrated Li+ and crown ether was discussed carefully. Firstly, it demonstrated that the water content of the extraction phase: B18C6 > B15C5 > B12C4. Secondly,the water in the extraction phase is mainly collected by solvent and crown ether, with the latter catching water primarily via Li+ coordination and weak interactions. In the end, focusing on the water captured by the crown ether through Li+ coordination, slope analysis and DFT calculations found that Li (H2O)4+ was removed three water molecules to complex with B12C4 or B15C5, whereas B18C6 tends to remove two water molecules. It is precious for a thorough grasp of the mechanism and procedure of Li+ extraction by crown ethers. What’s more, it offers novel strategies for investigating water content and transfer mechanisms in extraction systems.

Rheological analysis of network structure of raw natural rubber prepared by different processing techniques

The performance of raw natural rubber (NR) is dominated by its network structure, particular the levels of long chain branching (LCB) and entanglement. Here, three type of raw rubbers were prepared using different processing methods for commercial grade NRs. Linear and nonlinear viscoelastic behaviors, as well as stress relaxation, were analyzed to access their network structures. The third relative harmonic, phase angle, and first to second quarter-period integral ratio of stress curve were utilized as indicators for the nonlinearity of samples. By combining these values with flow activation energy and characteristic times, it can be confirmed that naturally coagulated NR showed higher elasticity than acid-coagulated NR due to high levels of LCB and entanglement, and hot air drying could lead to chain degradation. These findings correlated with molecular weight parameters, gel content and Mooney viscosity results. This research establishes a method for monitoring raw NR quality and predicting its properties.

Evidence of the double amplification of travelling planetary waves during the January 2021 sudden stratospheric warming

Abstract The in situ generation and characteristics of planetary waves (PWs) in the mesosphere and lower thermosphere (MLT) during the January 2021 sudden stratospheric warming (SSW) are investigated using the Navy Global Environmental Model. During a SSW, upward-propagating PWs can be absorbed, refracted, or amplified, the latter implying in situ PW generation. Additionally, asymmetric dissipation of GW drag in the MLT due to varying stratospheric winds may also seed PW generation. Ultimately, the interaction of waves with instability can enhance westward-propagating, quasi-stationary, or eastward-propagating components of PWs (WPW, QSPWs, and EPWs, respectively). The propagation pathway of a wave is diagnosed by its refractive index and is dependent on factors such as the baroclinic/barotropic stability of the atmosphere, the wave’s relative phase velocity, and the wavenumber. Through these pathways waves are able to transfer heat and momentum throughout the atmosphere. Under particular conditions, the waves can amplify in situ by extracting energy from the background wind. Our study identifies two scenarios in which WPWs and EPWs were amplified successively. Amplified WPWs propagated upwards and influenced the MLT while amplified EPWs propagated downwards and influenced the upper troposphere.

Electromagnetic |GE/GM| ratios of hyperons at large timelike q2

In recent years, it has become possible to measure not only the magnitude of the electric (GE) and magnetic (GM) form factors of spin 12 baryons, but also to measure the relative phases of those quantities in the timelike kinematic region. Aiming to interpret present |GE/GM| data on hyperons of the baryon octet, as well as to predict future data, we present model calculations of that ratio for large invariant 4-momentum square q2 in the timelike region (q2>0). Without any further parameter fitting, we extend to the timelike region a covariant quark model previously developed to describe the kinematic spacelike region (q2≤0) of the baryon octet form factors. The model takes into account both the effects of valence quarks and the excitations of the meson cloud which dresses the baryons. This application to the timelike region assumes an approximation based on unitarity and analyticity that is valid only in the large q2 region. Using the recent data from BESIII we establish the regime of validity of this approximation. We report here that our results for the effective form factor (combination of |GE| and |GM|) are in good agreement with the data already for q2 values above 15 GeV2. In addition, a more conservative onset of the validity of the approximation is provided by the newly available |GE/GM| data which suggest that our predictions may be compared against data for q2≥ 20 GeV2. This is expected in the near future, when the range of the present measurements is expanded to the 20–50 GeV2 region.

Introduction of a free sound system design exchange format (SDE) for data from different sound systems for noise predictions with complex summation

To consider the correlated sources of sound systems from different manufacturers in noise predictions equally with complex summation, a free exchange format for sound system planning software on the one hand and environmental noise software on the other is being defined in a cooperation with d&b audiotechnik, L-Acoustics and SoundPLAN: SDE = Sound/System Design/Data Exchange/Export This paper introduces the SDE format, its motivation and structure. With increasing open-air events in urban areas, potential problems with noise also increase. Proactive noise predictions can help prevent noise from becoming a problem in the first place. Until now it has not been possible to use data from planned sound systems from different manufacturers for equivalent calculations with complex summation. Modern sound systems have high directivity, especially loudspeaker arrays. The directivity of arrays results from superposition of sound waves from all loudspeakers. This effect is used specifically with line arrays and subwoofer arrays to optimize sound and coverage in audience areas. However, the resulting emission of an entire sound system is not constant over distance. Time-of-flight and relative phase at the receiver points must be considered with complex summation.

Directional excitation of structural vibrations due to correlated sources

Dynamical Energy Analysis (DEA) is an approach used to compute the vibro-acoustic response of complex structures to externally applied high-frequency excitation. DEA tracks the global energy flow in a structure in terms of a local ray tracing approach implemented on meshes. Due to its in-built directional set-up, the approach is ideally suited for modelling the response of structures to directional excitation. Examples thereof are dipole sources or - more generally - correlated and distributed source excitation such as due to a Turbulent Boundary Layer (TBL) excitation across an aircraft wing during flight. We will demonstrate here how such directional sources are implemented in a DEA setting. TBL induced sources or general correlated sources can be described in terms of appropriate force or wave correlation functions (CF). Using Wigner-transformation, these CFs can be associated with a directional energy flow source. Vibrational energy field results are presented for a pair of phase-locked point forces. Results are also presented for 9 point-sources, which demonstrate the ability to channel the energy flow away from the sources by carefully choosing their relative phases. An implementation of this approach within DEA is also presented, with results demonstrating strong agreement with direct calculations.