Phase Difference Research Articles

Electron dynamical phase difference and high-order harmonic frequency shift: A Bohmian-trajectory perspective

Electron dynamical phase difference and high-order harmonic frequency shift: A Bohmian-trajectory perspective

Research on a Novel Flux-Switching Permanent Magnet Motor with Adjustable Torque Ripple Using an Auxiliary Rotor

In the field of material manufacturing, torsional vibration has some benefits for cutting or forming processing. In principle, torsional vibration can be caused by the torque ripples of a motor. Flux-switching permanent magnet (FSPM) motors are doubly salient and generate torque ripples, making them an option for manufacturing. However, the amplitude of the torque ripples is related to the motor structure, and frequency has a linear relationship with running speed. The torque ripples cannot be controlled separately from the motor running speed at conventional current excitations. Thus, a novel FSPM machine with an auxiliary rotor (AR-FSPM) is proposed to adjust the torque ripples. The main rotor (m-rotor) outputs the power, and the auxiliary rotor (a-rotor) adjusts the ripple frequency. When the speed difference between two rotors is six times the m-rotor speed, the torque ripple waveforms overlap. In this case, by controlling the phase difference between the two rotors, the amplitudes of the torque ripples can be adjusted. In this study, the principle of this novel machine is introduced, and the relationship between the torque ripple performance and the geometric parameters of the auxiliary rotor is studied. Then, the torque ripple amplitude adjustment method for this machine is discussed. Finally, the prototype of this novel machine is presented to verify its feasibility.

A compact wideband coupler design for 5G applications

Abstract This paper presents the design of a compact broadband coupler specifically dedicated to 5G applications. The innovative approach proposed skillfully merges two distinct methods: the use of stepped impedance structures and meanders. The aim is not only to miniaturize the structure and extend the bandwidth, but also to maintain high performance, particularly within the 3.5 GHz core frequency band. The effectiveness of this approach is reflected in a remarkable reduction in size, down by 59% compared with conventional designs. In addition, the achievement of a large fractional bandwidth 40% is a significant result of this study. Equally important, this coupler offers a precise quadrature phase difference between its two output ports. The extensive experimental results confirm the relevance of this innovative approach, making it a promising choice for the design of compact, high-performance couplers for state-of-the-art 5G applications.

Investigation and optimization of parameters for bidirectional composite vibratory finishing of gears

ABSTRACT To meet the core requirements for uniform and efficient finishing of high-precision gears, a bidirectional composite vibratory finishing (BCVF) process was introduced. The influence of motion parameters (gear rotational speed n, vibration frequency f x and f z , vibration amplitude A x and A z , vibration phase difference ψ), process parameters (media loading height H, gear installation position h), gear parameters and container geometric parameters (cross-sectional shape, size L x × L y ) on the finishing effect was investigated by kinematic analysis and discrete element simulation (DEM). On this basis, the parameters with significant influence were selected and further optimized by gray relational analysis (GRA). Numerical simulations were carried out by orthogonal design, taking the cumulative contact energy and distribution uniformity on gear surface as evaluation indicators for multi-objective optimization. The results indicated that the affecting significance on comprehensive performance was ranked as f x > f z > A x > A z . Besides, the optimal parameter combination was obtained.

A moving-target imaging method for azimuth multi-channel HRWS SAR system based on spectrum energy distribution

ABSTRACT Azimuth multi-channel (AMC) synthetic aperture radar (SAR) systems can achieve high-resolution and wide-swath (HRWS) imaging, widely used in marine monitoring. However, for the moving ship targets irradiated by the AMC HRWS SAR system, false targets and defocus will appear in HRWS images caused by their motion. The existing methods behave poorly in case of low signal-to-noise ratio and channel non-uniformity. To improve the quality of HRWS images, the letter proposes a moving ship target imaging method based on spectrum energy distribution. Firstly, radial velocity of ship target is estimated by energy distribution factor parameter constructed by spectrum energy distribution. Secondly, the azimuth velocity is calculated by the phase difference between adjacent channels. Meanwhile, the importance of channel phase error on imaging is demonstrated. Finally, echo compensation and imaging method are performed to get a clear and focused image. Simulation experiments on point targets and area targets verify the effectivity of the proposed method. The proposed method can effectively suppress the false ship target, whose maximum energy is reduced from about −20 dB to below −40 dB, providing clearer images for the various application of different users.

Compact triple-band ring-shaped printed antenna with circular polarization

This research proposed a planar printed antenna with circularly polarized (CP) ability. The antenna can supply an impedance bandwidth (│S11│<−10 dB) of 60% (2.3–4.3 GHz), 32.4% (4.8–6.8 GHz), 5.5% (7–7.4 GHz), and 24.4% (8.6–11 GHz) in the operative frequency band. The designed antenna has a 3 dB polarization axial ratio (AR) bandwidth (BW) of 88% (1.4–3.6 GHz), 11.3% (5–5.6 GHz), and 1.15% (8.6–8.7 GHz). The patch antenna dimensions are 20mm × 20 mm. To enhance AR bandwidth, an inverted L-formed strip line is added to the radiator to generate two electric fields with 900 phase differences. The measurement maximum gain of this patch antenna is about 7 dBi from 2.5 to 4.4 GHz. This structure has a wide AR beam width from – 30° to +110° at 2.4 GHz, – 70° to +70° at 5.2 GHz, and – 60° to +20° at 8.65 GHz. The CP antenna exhibits a miniaturized size and low-cost structure with suitable CP radiation characteristics.

A Novel Polarity Correction Method for Waveform Stacking Location of Microseismic Events

Microseismic events play a crucial role in mapping fault and fracture distributions in natural and induced earthquakes. Detecting and localizing microseismic events is challenging due to low signal-to-noise ratios (SNR). Waveform stacking (WS) imaging location is a practical approach for automatically detecting and localizing microseismic events, assuming that the traveltime-corrected seismic waveforms will stack and enhance coherently. However, coherent stack enhancement is susceptible to polarity reversal caused by the non-explosive components of the source mechanism, which can lead to an unfocused source image, making it difficult to retrieve the optimal location accurately. In this study, we propose a new polarity correction method to address this issue, based on the characteristic that the instantaneous phase difference between two seismic signals with opposite polarity is ±p. First, the Hilbert transform is applied to the original seismic record to obtain instantaneous amplitude A(t) and phase f(t). Then, a new signal is constructed by multiplying A(t) with cos[2f(t)]. The constructed signals for different receivers have the same polarity, thereby being used to refocus the source image. Furthermore, they preserve both positive and negative amplitudes, which contributes to noise suppression. Synthetic tests show that the proposed method can effectively achieve polarity correction and noise suppression, enabling a high-resolution source image. Application to real hydraulic fracturing data demonstrates that the proposed method can detect and locate more microseismic events at the fracturing depths, suggesting its effectiveness and potential advantage in microseismic data processing. Since the polarity correction is performed in the data domain without relying on specific receiver layouts, the method is computationally efficient and could be applied to real-time microseismic monitoring across various sites, including hydraulic fracturing and volcano monitoring.

Influence of Oestradiol Fluctuations in the Menstrual Cycle on Respiratory Exchange Ratio at Different Exercise Intensities: A Systematic Review, Meta-Analysis and Pooled-Data Analysis

Background: Oestradiol has been implicated as a factor in substrate utilisation in male and mouse studies but the effect of acute changes during the menstrual cycle is yet to be fully understood. Objective: To determine the role of oestradiol in respiratory exchange ratio (RER) during exercise at various intensities. Methods: This systematic review was conducted and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. From inception to November 2023, four online databases (Cochrane, SPORTDiscus, MEDline and Web of Science) were searched for relevant articles. Studies that reported a resting oestradiol measurement in naturally menstruating women with exercise at a percentage of maximal aerobic capacity (%V˙O2max) were included. Mean and standard deviation for oestradiol, RER and exercise intensity were extracted and study quality assessed using a modified Downs and Black checklist. Risk of bias was assessed using I2 measure of heterogeneity and Egger’s regression test, assessment of bias from methodological quality was identified by sensitivity analysis. Eligible datasets were extracted for pairwise comparisons within a meta-analysis and correlation between change in oestradiol and change in RER. Data were also pooled to produce a mean and standard deviation for RER for menstrual stage and for low and high oestradiol groups. Results: Twenty-four articles were identified, over 50% were identified as high quality. Sixteen articles included datasets eligible for meta-analysis. Eleven articles utilised a submaximal constant-load exercise intensity, finding a standardised mean difference of − 0.09 ([CI: −0.35–0.17], p = 0.5) suggesting no effect of menstrual phase on constant-load exercise RER. In six articles using incremental exercise tests to exhaustion, a standardised mean difference of 0.60 ([CI 0.00–1.19], p = 0.05) was identified towards a higher maximal RER attained in follicular compared to luteal phase. There was no correlation (R = −0.26, p = 0.2) between change in oestradiol and change in RER between phases. All 24 articles, totalling 650 participants, were included in pooled analysis. When grouped by menstrual cycle phase or when grouped by oestradiol levels, RER was higher in the follicular phase than the luteal phase at low and high constant load exercise intensities. Discussion: Findings from the pooled-analysis and meta-analysis suggest that there may be menstrual cycle phase differences in RER that are intensity dependent. These differences may be related to sex hormone levels, but this was not supported by evidence of correlation between differences in RER and differences in oestradiol. At present, it remains best practice to assess performance in the same menstrual cycle phase if seeking to assess change from baseline.

Bloch sphere representation for Rabi oscillation driven by Rashba field in the two-dimensional harmonic confinement system

Abstract We studied the dynamical properties of Rabi oscillations driven by an alternating Rashba field applied to a two-dimensional (2D) harmonic confinement system. We solve the time-dependent (TD) Schrödinger equation numerically and rewrite the resulting TD wavefunction onto the Bloch sphere (BS) using two BS parameters of the zenith (θB) and azimuthal (φB) angles, extracting the phase information φB as well as the mixing ratio θB between the two BS-pole states.&amp;#xD;&amp;#xD;We employed a two-state rotating wave (TSRW) approach and studied the fundamental features of θB and φB over time. The TSRW approach reveals a triangular wave formation in θB. Moreover, at each apex of the triangular wave, the TD wavefunction passes through the BS pole, and the state is completely replaced by the opposite spin state. The TSRW approach also elucidates a linear change in φB. The slope of φB vs. time is equal to the difference between the dynamical terms, leading to a confinement potential in the harmonic system. The TSRW approach further demonstrates a jump in the phase difference by π when the wavefunction passes through the BS pole.&amp;#xD;&amp;#xD;The alternating Rashba field causes multiple successive Rabi transitions in the 2D harmonic system. We then introduce the effective BS and transform these complicated transitions into an equivalent "single" Rabi one. Consequently, the effective BS parameters θB eff and φB eff exhibit mixing and phase difference between two spin states α and β, leading to a deep understanding of the TD features of multi-Rabi oscillations. Furthermore, the combination of the BS representation with the TSRW approach successfully reveals the dynamical properties of the Rabi oscillation, even beyond the TSRW approximation.

Seismic Response of Ground Penetrating Shield Tunnels Under Lateral Harmonic Excitations: Insights From Shaking Table Test

ABSTRACTThe ground penetrating shield tunnel (GPST) method offers a streamlined approach to tunnel construction in soft ground with limited open‐cut excavation. To explore the seismic response of GPST linings, a series of large‐scale shaking table tests have been conducted, including a variety of seismic excitations. This paper focuses on lateral harmonic excitation. The model tunnel spans a total length of 7.7 m, with the embedment depth ranging from −0.5 to 0.5 times its diameter. The design and fabrication of the model tunnel are presented, including the segmental lining, along with circumferential and longitudinal joints. The soil was modeled with artificial synthetic soil, aiming to simulate the static and dynamic characteristics of the prototype soil. Its composition was adjusted and verified through element tests. The experimental results provide insights into the seismic response of the soil–tunnel system, the ovaling deformation of the segmental lining, as well as the response of the joints between lining segments. The results reveal a strong influence of embedment on tunnel seismic response. The reduction of tunnel embedment leads to a significant increase in lining accelerations and a phase difference, resulting in a “whiplash” effect. In contrast, the ovaling deformation of the lining and the joint apertures decrease with the reduction of embedment. In the sections of the tunnel that are fully embedded, both the acceleration and deformation response of the lining are governed by soil–structure interaction (SSI). A pronounced whiplash effect is observed in the sections of the tunnel that are not fully embedded, due to the absence of soil confinement. The presented experimental results offer valuable insights into the seismic response of GPSTs, which can be of crucial importance for their seismic design.

Uncovering Key Predictive Channels and Clinical Variables in the Gamma Band Auditory Steady-State Response in Early Stage Psychosis - a Longitudinal Study.

Psychotic disorders are characterized by abnormalities in the synchronization of neuronal responses. A 40 Hz gamma band deficit during auditory steady-state response (ASSR) measured by electroencephalogram (EEG) is a robust observation in psychosis and is associated with symptoms and functional deficits. However, the majority of ASSR studies focus on specific electrode sites, while whole scalp analysis using all channels, and the association with clinical symptoms, are rare. In this study, we use whole-scalp 40 Hz ASSR EEG measurements-power and phase locking factor-to establish deficits in early-stage psychosis (ESP) subjects, classify ESP status using an ensemble of machine learning techniques, identify correlates with principal components obtained from clinical/demographic/functioning variables, and correlate functional outcome after a short-term follow-up. We identified significant spatially-distributed group level differences for power and phase locking. The performance of different machine learning techniques and interpretation of the extracted feature importance indicate that phase locking has a more predictive and parsimonious pattern than power. Phase locking is also associated with principal components composed of measures of cognitive processes. Short-term functional outcome is associated with baseline 40 Hz ASSR signals from the FCz and other channels in both phase locking and power. This whole scalp EEG study provides additional evidence to link deficits in 40 Hz ASSRs with cognition and functioning in ESP, and corroborates with prior studies of phase locking from a subset of EEG channels. Confirming 40 Hz ASSR deficits serves as a candidate phenotype to identify circuit dysfunctions and a biomarker for clinical outcomes in psychosis.

Neural tracking of the speech envelope predicts binaural unmasking.

Binaural unmasking is a remarkable phenomenon that it is substantially easier to detect a signal in noise when the interaural parameters of the signal are different from those of the noise - a useful mechanism in so-called cocktail party scenarios. In this study, we investigated the effect of binaural unmasking on neural tracking of the speech envelope. We measured EEG in 8 participants who listened to speech in noise at a fixed signal-to-noise ratio, in two conditions: one where speech and noise had the same interaural phase difference (both speech and noise having an opposite waveform across ears, SπNπ), and one where the interaural phase difference of the speech was different from that of the noise (only the speech having an opposite waveform across ears, SπN). We measured a clear benefit of binaural unmasking in behavioural speech understanding scores, accompanied by increased neural tracking of the speech envelope. Moreover, analysing the temporal response functions revealed that binaural unmasking also resulted in decreased peak latencies and increased peak amplitudes. Our results are consistent with previous research using auditory evoked potentials and steady-state responses to quantify binaural unmasking at cortical levels. Moreover, they confirm that neural tracking of speech is associated with speech understanding, even if the acoustic signal-to-noise ratio is kept constant. From a clinical perspective, these results offer the potential for the objective evaluation of binaural speech understanding mechanisms, and the objective detection of pathologies sensitive to binaural processing, such as asymmetric hearing loss, auditory neuropathy and age-related deficits.

Matching for realizing high-speed reading in holographic data storage system

In the era of big data, data storage density, and reading speed are becoming increasingly important. Therefore, achieving high-speed data reading in the holographic data storage system is particularly crucial. The key to realizing high-speed data reading in the holographic data storage system is to ensure frame rate matching among key devices. In this paper, we research the frame rate matching of the digital micro-mirror device (DMD), the acousto-optic modulator (AOM), the high-speed camera, and the electric displacement table loaded with materials. We have determined the maximum matching frame rate of the system with respect to changes in the exposure time and resolution of the camera, as well as the phase difference between the AOM and DMD. By finely adjusting the parameters of key devices in the system, we can ultimately achieve a matching frame rate of 18kHz. Under conditions where the electric displacement table speed is 40 mm/s, and the light intensity of the incident materials is 0.6 mW, the holographic data storage system can attain a reading frame rate of up to 8kHz, resulting in a data transfer rate of 5.8GB/s.

A 1-bit passive reconfigurable metasurface for wide-angle scanning and broad-beam reflection

ABSTRACT A reconfigurable reflective metasurface design is proposed in this letter, allowing for beam scanning capabilities. This paper integrates a tunable capacitor into the metasurface unit. This paper integrates a tunable capacitor into the metasurface unit. The resonant characteristics of the metasurface unit are controlled by the tunable capacitor, which can be adjusted by changing the rotation angle of the metal plate on the tunable capacitor. By rotating the metal plate of the capacitor, it achieves state 1 at maximum capacitance and state 0 at minimum capacitance, resulting in a phase difference of 180° ± 20° between the states, thereby enabling 1-bit phase control. Leveraging the principle of phase compensation, the phase distribution of the array is designed to exhibit directional radiation characteristics. A reflective metasurface composed of a 20 × 20-element array is designed and simulated with these characteristics. The simulation results indicate that the scanning angle of the array-reflected beam can reach ± 50°, with a peak gain exceeding 14.6 dBi, an average gain of 13.8 dBi, and a gain loss of 1.5 dB. The beam’s 3 dB beamwidth exceeds 15°, enabling broader coverage. Joint simulations in typical indoor scenarios confirm the improved signal strength, highlighting the array’s versatility. This design allows the reflective array to function as a passive reflector relay, effectively improving signal coverage in indoor NLOS.

A Novel Synchronization Strategy for Distributed Energy Resources in Weak Grids Using Remote Strong Grid Sensing

This paper proposes a novel strategy for the current injection-based control of distributed energy resources connected to weak grids via a voltage source converter. The current injection controller is no longer synchronized with the point of common coupling but with the strong grid point voltage. The strong grid synchronization control strategy improves the output dynamics of the voltage source converter and recovery after faults in weak grids. The phase difference between the voltage source converter and the strong grid voltages caused by the long power lines does not affect the power control. Furthermore, a time delay-compensation method is proposed which tolerates the communication time delay introduced by the transmission of the synchronization signal from the strong grid point. The performance of the proposed control strategy is verified in detail using MATLAB 2023b simulations and real-time digital simulations on a medium voltage model and also validated in an experiment on a low-voltage grid-feeding inverter setup.

A Narrative Exploration of Family Members' Perspectives of Life Story Phases Following Transition of an Older Family Relative Into Long-Term Care.

The transition of an older person from a home environment into long-term care is frequently unplanned and complex. Little is known about how relatives make sense of supporting the transition of their relatives to long-term care. This study explored family members' narratives of the process of supporting the transition of their older relative into long-term care. Life stories of six relatives who supported transitioning their older family relatives into a nursing home were collected using open narrative questioning in accordance with the Biographical Narrative Interpretive Method. Data was analysed using a dialogic/performance analysis narrative analytic method. Four key life story phases were identified: before transition, crisis event, transition and after transition. These phases varied in time duration and involvement of healthcare providers. The longest phase was 'before transition' where a process of slow deterioration became more apparent to the participants retrospectively. This was followed by the shortest period 'crisis event' where the older person was admitted to tertiary care. Two permeating themes: family dynamics and knowledge/understanding underpinned all life story phases. Relatives' knowledge, family dynamics and positioning of self-informed the duration of the life story phases of participants as they navigated the transition. Understanding nuanced differences in relatives' life story phases highlights how timing of information provision can affect the emotional adjustment of relatives experiencing this challenging process. Both community and gerontological nurses' offer real potential to provide tailored and effective responses to relatives depending on each life phase. Sequencing of information appropriate to the life phase could potentially ease the stress associated with transitioning to nursing home care, possibly preventing a crisis event from occurring. Anticipatory conversations also offer potential to alleviate relatives' concerns through life story phases.

The Deformation of a Liquid Metal Droplet Under Continuous Acceleration in a Variable Cross-Section Groove

This paper constructs a numerical simulation model for the deformation of droplets in a variable cross-section groove of a liquid droplet MEMS switch under different directions, amplitudes, frequencies, and waveforms of acceleration. The numerical simulation utilizes the level set method to monitor the deformation surface boundary of the metal droplets. The simulation outcomes manifest that when the negative impact acceleration on the X-axis is 12.9 m/s2, the negative impact acceleration on the Y-axis is 90 m/s2, the negative impact acceleration on the Z-axis is 34.5 m/s2, and the metal droplet interfaces with the metal electrode. The droplet deformation under the effect of a sine wave acceleration signal in the X and Y directions is lower than that under impact acceleration, while in the Z direction, the deformation is higher than that under impact acceleration. The deformation of metal droplets under square wave acceleration is more pronounced than that under sinusoidal wave acceleration. The deformation escalates with the augmentation in square wave amplitude and dwindles with the reduction in square wave acceleration frequency. Furthermore, there exists a phase difference between the deformation curve of the metal droplet and the continuous acceleration signal curve, and the phase difference is dependent of the material properties of the metal droplet. This work elucidates the deformation of the liquid-metal droplets under continuous acceleration and furnishes the foundation for the continuous operation design of MEMS droplet switches.

Nonlinear detection of phase difference in optical interference using computer generated hologram assisted common-path three-beam interferometry

Nonlinear detection of phase difference in optical interference using computer generated hologram assisted common-path three-beam interferometry

Investigation of the aerodynamic performance of the dragonfly-inspired tandem wings considering the coupling between the stroke plane and phase difference

The dragonfly's tandem wings can make full use of the interference of various spatial vortices to obtain efficient flight capability. The complex coupling among multiple motion parameters will have an important influence on the interference between the forewing (FW) and hindwing (HW). In this paper, the aerodynamic performance of the dragonfly-inspired tandem wings is analyzed using the Computational Fluid Dynamics (CFD) method considering the coupling effect of the stroke plane and phase difference. The variation of the force coefficient, vortex structure and aerodynamic efficiency of the tandem wings in forward flight are analyzed, respectively. The results show that the stroke plane angle affects the distribution of the leading edge vortex (LEV) and trailing edge vortex (TEV), which primarily controls the trend of horizontal force variation. The phase difference of tandem wings will change the fluctuation of the horizontal force coefficient curve by affecting the meeting time of the forewing and hindwing. However, with the increase of stroke plane angle, the fluctuation of aerodynamic coefficient caused by phase difference will decrease. The propulsion efficiency(η) and power loading(PL) can be improved through increasing the stroke plane angle and selecting a reasonable phase difference. The conclusion can provide theoretical guidance for the design of the dragonfly-inspired tandem flapping wing aircraft (DTFWA) and the choice of motion parameters.

Effects of oscillation frequency, phase difference, and arrangement of two triangular cylinders on the hydrothermal performance of a channel

This study aims to numerically explore the effects of two cylinders with triangular cross sections, undergoing transverse oscillation on the heat and fluid flow within a channel. The governing equations along with the pertinent initial and boundary conditions are solved using the finite element method. The results are validated against the available data in the literature, demonstrating admissible agreement. Different oscillation frequencies, phase differences, and arrangement of the cylinders are considered. The results are presented in terms of temperature, pressure, and vorticity contours, alongside the Nusselt (Nu) number and thermal performance index (TPI). The Reynolds number based on the triangle's side length (Reb=200) is deliberately chosen to induce the vortex shedding phenomenon in the wake of the cylinders. For a single oscillatory cylinder, an optimal oscillation frequency fr=0.5 was found resulting in a remarkable increase in 22.3% and 33.1% in the Nu number and TPI, respectively, when compared to the fixed single cylinder. Using the obtained optimal oscillation frequency fr=0.5, the side-by-side arrangement of two cylinders gives rise to a higher TPI than the tandem one. The maximum TPI in side-by-side arrangement corresponds to the oscillation phase of φ=π/6, which is about 1.69. In tandem arrangement, it corresponds to φ=π/3, which is approximately 1.3. Furthermore, the oscillation phase φ=π exhibits the lowest TPI for both arrangements.