Reference Phase Research Articles

Complex network control and stability through distributed critic‐based neuro‐fuzzy learning

AbstractInspired by advancements in swarm autonomous vehicles and intelligent control systems, this research addresses the issue of frequency synchronization and phase tracking in oscillator networks. A novel distributed consensus protocol and a reinforcement learning algorithm for a multi‐agent network with a leader–follower topology, considering stability conditions, are developed. The critic‐based neuro‐fuzzy learning (CBNFL) method aims to achieve consensus and minimize local tracking errors. Additionally, an explicit synchronization condition for the network using the Lyapunov theorem is derived. Each vehicle tracks its reference phase and frequency. Employing a fuzzy critic to evaluate the current state and generate a stress signal for the controller, the method prompts adaptive parameter adjustments to minimize this signal. The proposed design's versatility and adaptability to various networks demonstrate robustness against dynamic vehicle properties and network parameter uncertainties, ensuring consistent controller performance. This approach exhibits high scalability, accommodating numerous autonomous agents. To validate the proposed learning method's efficacy, numerical simulations are conducted on a network of five oscillators. The outcomes of implementing CBNFL compared with a conventional PI controller underscore the CBNFL method's superior performance and robustness in maintaining network stability and achieving synchronization.

Unbalance detection of threshing cylinder in non-stationary rotation based on variational mode extraction

The rotating speed of the threshing cylinder was hardly constant in practice due to transmission error and cylinder speed would change with feed quantity to ensure the grain threshing effect. This paper proposed a novel unbalance detection method for non-stationary rotation. Variational mode extraction (VME) was introduced to extract unbalanced vibration signal and the unbalance feature index (UFI) was constructed as a criterion of weighting factor selection. Moreover, the unbalance phase calculation method and phase reference in non-stationary were proposed, which could eliminate the influence of speed change. The advantages of VME and UFI were verified by simulation, and the effectiveness of proposed method was proved by experiment on multi-cylinder test rig and combine harvest. This method could realize the reconstruction of unbalanced vibration signal in time-varying speed with low computational cost, break the strict requirement of constant speed of the existing balancing method.

Second harmonic generation null angle polarization analysis for determining interfacial potential at charged interfaces.

Methods of quantifying the electrostatics of charged interfaces are important in a range of research areas. The surface-selective nonlinear optical technique second harmonic generation (SHG) is a sensitive probe of interfacial electrostatics. Recent work has shown that detection of the SHG phase in addition to its amplitude enables direct quantification of the interfacial potential. However, the experimental challenge of directly detecting the phase interferometrically with sufficient precision and stability has led to the proposal and development of alternative techniques to recover the same information, notably through wavelength scanning or angle scanning, each of which has their own associated experimental challenges. Here, we propose a new polarization-based approach to recover the required phase information, building upon the previously established nonlinear optical null ellipsometry (NONE) technique. Although NONE directly returns only relative phase information between different tensor elements of the second-order susceptibility, it is shown that a symmetry relation that connects the tensor elements of the potential-dependent third-order susceptibility can be used to generate the absolute phase reference required to calculate the interfacial potential. The sensitivity of the technique to potential at varying surface charge densities and ionic strengths is explored by means of simulated data of the silica:water interface. The error associated with the use of the linearized Poisson-Boltzmann approximation is discussed and compared to the error associated with the precision of the measured NONE null angles. Overall, the results suggest that NONE is a promising approach for performing phase-resolved SHG based quantification of interfacial potentials that experimentally requires only the addition of standard polarization optics to the basic single-wavelength, fixed-angle SHG apparatus.

Die „fünfte Suburbanisierung“ – Perspektiven suburbaner Raumentwicklung in den 2020er-Jahren

Germany is currently experiencing a renewed rise of suburbanisation and an associated increase in urban expansion in the peripheries of large cities. How this development—referred to below as the “fifth suburbanisation” in the history of this country—can be characterized in the light of earlier phases of intraregional deconcentration is the topic of this paper. The four historical reference phases are not to be understood as clearly distinguishable and successive developments. Their conceptualization is less temporal than structural-material, socio-spatial, institutional, cultural, economic and political-discursive. The focus is on characteristics of built environments typical of each phase, specific social and economic drivers, dominant housing and planning policies, socio-cultural meanings and values as well as social embedding and negotiation processes. Suburban development of the 2020s will take place in a socio-economically and institutionally changed process field, even though there is still little empirical evidence in this regard. Accordingly, this paper also aims to call for a discussion on new research desiderata and realistic policy designs for suburban spatial development in the 2020s. A historical contextualization of the current development and planning processes is considered essential.

The impact of institutional measures on optimal use of intravenous immunoglobulin.

Intravenous immunoglobulin (IVIG) shortage represents an emerging issue in transfusion medicine. Limited data are available to determine effective strategies for optimal use. The objective of this retrospective observational study was to determine the impact of institutional measures on IVIG use at a large academic center. IVIG infusions from November 26, 2018 to September 25, 2022 were categorized according to their appropriateness (Recommended, Option of treatment, or Unrecommended), based on provincial guidelines, and separated into three phases: Reference, Transition, and Post-Implementation phases, the latter following the adoption of restrictive measures, including mandatory standardized order forms, a blood bank gatekeeping strategy, and the creation of a stewardship committee. A total of 5431 IVIG infusions were administered to 544 patients, accounting for 295,033 g. The most common indication categories were neurology (30.4%), immunology (29.0%), and hematology (17.4%). From Reference to Post-Implementation phase, IVIG infusions decreased from 2275 to 2000 with unrecommended indications dropping from 9.5% to 7.4% (p = 0.01), and a global reduction of 23.0% (from 131,163 g to 100,936 g of IVIG). Decrease in chronic immunomodulation accounted for 48.3% of total reduction (14,610 g of 30,227 g), whereas single-use immunomodulation, 40.5% (12,237 g of 30,227 g). Moreover, an absolute reduction of 16.9% was observed in orders exceeding the recommended doses (20.8% to 3.9%; p < 0.0001). Together, the unrecommended and excessive IVIG doses decreased from 19,975 g (15.2%) to 6670 g (6.6%). A global reduction in IVIG use and a preferential decrease in the unrecommended orders were observed, most likely attributable to the bundle of restrictive strategies implemented.

LUT-based phase error compensation method for large-step phase-shifting algorithm in DLP4500-based FPP system.

As a low-cost professional digital light projection device, the DLP4500 have been widely applied in fringe projection profilometry (FPP), for both laboratory and practical application. However, our recent experiments revealed a new hardware-induced projection instability when the projection pattern data exceeds its buffer capacity (48 bits). This phenomenon undermines the measurement accuracy advantage of the phase-shifting (PS) algorithms with large number of shifting steps, and eventually leads unwanted and complicated error to 3D reconstruction. In this paper, we experimentally investigate the new hardware-induced phase error and proposed a LUT-based phase error compensation method. In this method, a standard plate with a precision manufactured plate is used as the standard reference for the phase error evaluation, where an ideal plane fitting and the projector pixel reprojection process are introduced to generate the ideal reference phase. Comprehensive experiments are conduct to verify the stability of the proposed method in LUT creation. Comprehensive experiments are conduct, and the results show that (i) the method works creates LUTs stably at different plate positions, (ii) the plate with regular manufacturing accuracy (not exceeding 0.01 mm) can meet the application requirements of the proposed method. Both quantitative and qualitative experimental results successfully verify the effectiveness of proposed method in LUT creation and phase error reduction.

Aspect ratio optimization of piezoelectric extensional mode resonators for quality factor and phase noise performance enhancement

Abstract This study focuses on optimizing the resonator geometry via the aspect ratio design of a width-extensional mode resonator to improve its quality factor (Q), which is one of the critical performance parameters for resonators in either sensing (Allan deviation) or frequency reference (phase noise) applications. The proposed approach uses finite element analysis to reduce the strain energy at anchor supports by altering the resonator geometric structure, thereby reducing energy loss through anchors. Moreover, process limitations on feature sizes are used as constraints to find aspect ratios that can not only increase the Q but also reduce spurious modes near the targeted frequency. The devices were fabricated using AlN thin film piezoelectric on a substrate (TPoS) process. The simulated energy dissipation trends for specific length-to-width (L/W) ratios closely match the measured changes in the resonator Q values in vacuum. In vacuum, the highest Q-factor achieved by the device is close to 8816, with a motional resistance of a few tens of ohms. Additionally, a board-level oscillator realized using a commercial low-noise amplifier exhibits phase noise performance of −141.21 dBc Hz−1 and −164.25 dBc Hz−1 at 1 kHz and 1 MHz frequency offsets, respectively. The calculated figures of merit for these offsets are 204 and 168, respectively.

Full-field three-dimensional system calibration for composite surfaces reconstruction

The accurate calibration of composite surface measurement systems for specular and diffused surface is of great importance in a number of industrial applications. This paper addresses the challenges in calibrating composite surface reconstruction by proposing a comprehensive full-field calibration method. The principal innovation is the construction of a comprehensive reference phase and the pixel-by-pixel calibration of system parameters within the same coordinate system. The details are as follows: (1) construct a complete reference phase for the composite surfaces through external parameter constraints phase fusion and interpolation; (2) calibrate the mapping relationship coefficients, compensate the accuracy degradation of the partial reflection. Experimental results validate the accuracy of the full-field calibration data, demonstrating the effectiveness and feasibility.

Utilizing the Concept of Entropy in the Second Law of Thermodynamics to Determine Risk Levels Associated with Groundwater and Bottled Drinking Water Using Rainwater Quality as a Clean Reference

The concept of entropy as a state function is employed in this paper within a radiation system designed to address the role of atomic disturbance in determining the levels of physical permeability changes in the studied states, comparing the results with those of a clean phase. This investigation begins with samples prepared for characterization tests using a unique technique for electromagnetic irradiation. The samples included: (1) a rainwater sample carefully collected during the first week of February 2024, serving as a high-quality natural reference in its aqueous phase; (2) a sample from a 42-meter-deep drinking water well (GW) in Ghout al-Dees, west of Tripoli, Libya; and (3) a bottled water sample (AA-WS3) commonly available in the Libyan market. The test results focused on the values of the physical property (τC), identified from the relationship between the entropy operator and time, as a physical fingerprint that accurately detects disturbed material permeability. The study concludes with a section linking the properties of the natural reference phase to the fingerprint characteristics of the studied samples, providing an approach to assess the quality of the tested water samples against the ideal chemophysical quality of rainwater. This led to findings that (1) the groundwater quality (QAA-WS2) was 76.92%, and (2) the quality of bottled water available in the Libyan market (QAA-WS3) was 74.57%, highlighting the role of the polymer composition in plastic container packaging as an additional factor, alongside the structures enclosing water sources, as in the case of the groundwater well exposed to contamination. Keywords: atomic disturbance, entropy, chemical identity, atomic irradiation, wave gaps

Gravitational Wave Ringdown Analysis Using the F -statistic

After the final stage of the merger of two black holes (BHs), the ringdown signal takes an important role in providing information about the gravitational dynamics in strong field. We introduce a novel time-domain (TD) approach, predicated on the F -statistic, for ringdown analysis. This method diverges from traditional TD techniques in that its parameter space remains constant irrespective of the number of modes incorporated. This feature is achieved by reconfiguring the likelihood and analytically maximizing over the extrinsic parameters that encompass the amplitudes and reference phases of all modes. Consequently, when performing the ringdown analysis under the assumption that the ringdown signal is detected by the Einstein Telescope, the parameter estimation computation time is shortened by at most 5 orders of magnitude compared to the traditional TD method. We further establish that traditional TD methods become difficult when including multiple overtone modes due to close oscillation frequencies and damping times across different overtone modes. Encouragingly, this issue is effectively addressed by our new TD technique. The accessibility of this new TD method extends to a broad spectrum of research and offers flexibility for various topics within BH spectroscopy applicable to both current and future gravitational wave detectors.

Current Profiling Control for Torque Ripple Reduction in the Generating Mode of Operation of a Switched Reluctance Motor Drive

The benefits of utilizing Switched Reluctance Motor (SRM) drives in traction applications can be realized fully by improving the electromagnetic performance of the machine in the generating mode of operation. This is because the generating capability of an SRM drive could be utilized for regenerative braking and also for the machine to generate power for the vehicle while the engine is in operation. In this paper, a current profiling-based control strategy is proposed to reduce the torque ripple in an SRM drive in the generating mode. The reference current profile is determined using a multi-step computation method to minimize torque ripple and maximize the average torque. The reference current profile is derived based on the reference torque command by utilizing the torque–current–angle look up table. The flux linkage characteristics of the SRM are considered when deriving the phase reference current profile. Then, the performance of the proposed profiling method, analytical linear and cubic torque sharing functions (TSFs), and the average torque optimization scheme are compared using simulation results. Finally, an experimental correlation is performed to validate the efficacy of the proposed control scheme.

Dynamic phase measurement based on two-step phase-shifting interferometry with geometric phase grating

Abstract This paper proposes a novel dynamic 2-step phase-shifting interferometry method with a geometric phase grating and direct aberration-free object phase recovery algorithm. By exploring the amplitude-phase modulation property of the geometric phase grating, two-step phase-shifting interferograms with π / 2 phase shift can be obtained in a single shot through two kinds of spatial-multiplexing arrangements. Then the restriction on the background uniformity of the 2-step phase-shifting algorithms and the system aberration can be avoided simultaneously, based on the presented direct and fast object phase demodulation strategy with an object-free state recorded in advance, so an accurate object measurement result can be guaranteed. Accordingly, a detailed analysis of the theoretical model of error sources is conducted by taking the depolarization error of geometric phase grating and phase measurement model error into consideration, with a Least Squares Iteration optimization strategy established to further improve the measurement accuracy. Experiments on various types of phase objects, such as a photo-etched quartz substrate, the spatial light modulator, and a silicon chip, validate the effectiveness and accuracy of our method when compared with the reference phase obtained from 4-step temporal phase-shifting method. The dynamic phase measurement capability is demonstrated by exhibiting the evaporation process of alcohol droplet.

Regularities and Anomalies in Neon Matrix Shifts of Hydrogen-Bonded O-H Stretching Fundamentals.

O-H bond stretching vibrations in hydrogen-bonded complexes embedded into cryogenic neon matrices are subtly downshifted from cold gas phase reference wavenumbers. To the extent that this shift is systematic, it enables neon matrices as more universally applicable spectroscopic benchmark environments for quantum chemical predictions. Outliers are indicative of either an assignment problem in one of the two cryogenic experiments or they reveal interesting dynamics or structural effects on the complexes as a function of the environment. We compile 6 literature-known pairs of experimental data in jet and neon matrix expansions and realize a 6-fold expansion of that number through targeted matrix isolation and/or slit jet expansion spectroscopy presented in this work. In many cases, the neon matrix shift is less than the uncertainty of the currently best-performing blind quantum chemical predictions for the gas phase, but in specific cases, it may exceed the currently achievable theoretical accuracy. Some evidence for a positive correlation of the matrix shift with the hydrogen bond shift is found, similar to observations for helium nanodroplets. Outliers in particular for water acting as a donor are discussed, and in a few cases they call for a future reinvestigation. Substantial improvement in the correlation of the matrix shift with the hydrogen bond shift is achieved for ketone monohydrates by removing a vibrational resonance. New insights into nitrile hydration isomerism are obtained, and the linear OH stretching spectrum of the jet-cooled ammonia-water complex is presented for the first time. Vibrational spectroscopy in weakly perturbing solid rare gas quantum matrices for the benchmarking of gas phase theory and future explicit theoretical treatments of the quantum matrix environment to better understand the outliers are both encouraged.

Quantum phase estimation and realistic detection schemes in Mach-Zehnder interferometer using SU(2) coherent states

In quantum parameter estimation, the quantum Cramér-Rao bound (QCRB) sets a fundamental limit on the precision achievable with unbiased estimators. It relates the uncertainty in estimating a parameter to the inverse of the quantum Fisher information (QFI). Both QCRB and QFI are valuable tools for analyzing interferometric phase sensitivity. This paper compares the single-parameter and two-parameter QFI for a Mach-Zehnder interferometer (MZI) with three detection schemes: single-mode and difference intensity detection, neither has access to an external phase reference and balanced homodyne detection with access to an external phase reference. We use a spin-coherent state associated with the su(2) algebra as the input state in all scenarios and show that all three schemes can achieve the QCRB for the spin-coherent input state. Furthermore, we explore the utilization of SU(2) coherent states in diverse scenarios. Significantly, we find that the highest achievable precision occurs when the total angular momentum quantum number, j, is high. We further demonstrate that under these optimal conditions, all detection schemes can achieve the QCRB by utilizing SU(2) coherent states as input states.

Effect of chloroquine pre-treatment on the metoclopramide’s pharmacokinetics after their co-administration

ABSTRACT Background This study evaluated the pharmacokinetic interactions of orally administered chloroquine and metoclopramide. Methods The study employed a randomized and two-phase cross-over design with 4-week washout plan. Twelve healthy male volunteers were shortlisted according to the set criteria and were administered with metoclopramide 10 mg PO and chloroquine (a total of 1500 mg) at different intervals which were (500 mg at 0, 6, and 24 h). The concentration of chloroquine and metoclopramide in the blood samples was estimated using a validated HPLC-UV technique to affirm the maximum concentration (Cmax), time to reach Cmax (Tmax), and area under the curve (AUC). Results Cmax, T1/2, and AUC of metoclopramide were increased up to 20, 10, and 47.8%, respectively, by the concomitantly administering Chloroquine. Chloroquine-treated phase showed increased values of Cmax (ng/ml), AUC (ng.h/ml), and T½ (h), i.e. 41.35 ± 1.61, 504.12 ± 66.25, and 5.72 ± 2.63, as compared to that reference phase i.e. 34.52 ± 4.92, 341.14 ± 112.8, and 5.19 ± 1.14, respectively. Conclusions Chloroquine was found to attenuate CYP2D6 activity in healthy Pakistani male volunteers. Hence, patients that are prescribed with metoclopramide or other CYP2D6-substrate drugs require a dose adjustment when administered with chloroquine.

On Energy‐Aware Hybrid Models

AbstractThis study proposes deterministic and stochastic energy‐aware hybrid models that should enable simulations of idealized and primitive‐equations Geophysical Fluid Dynamics (GFD) models at low resolutions without compromising on quality compared with high‐resolution runs. Such hybrid models bridge the data‐driven and physics‐driven modeling paradigms by combining regional stability and classical GFD models at low resolution that cannot reproduce high‐resolution reference flow features (large‐scale flows and small‐scale vortices) which are, however, resolved. Hybrid models use an energy‐aware correction of advection velocity and extra forcing compensating for the drift of the low‐resolution model away from the reference phase space. The main advantages of hybrid models are that they allow for physics‐driven flow recombination within the reference energy band, reproduce resolved reference flow features, and produce more accurate ensemble forecasts than their classical GFD counterparts. Hybrid models offer appealing benefits and flexibility to the modeling and forecasting communities, as they are computationally cheap and can use both numerically‐computed flows and observations from different sources. All these suggest that the hybrid approach has the potential to exploit low‐resolution models for long‐term weather forecasts and climate projections thus offering a new cost effective way of GFD modeling. The proposed hybrid approach has been tested on a three‐layer quasi‐geostrophic model for a beta‐plane Gulf Stream flow configuration. The results show that the low‐resolution hybrid model reproduces the reference flow features that are resolved on the coarse grid and also gives a more accurate ensemble forecast than the physics‐driven model.

Neural network enhanced time-varying parameter estimation via weak measurement.

Weak measurement is employed to measure faint signals due to its capability to amplify detection results above technical noise. However, achieving high amplification effects requires accurate adjustment to the experimental system. Estimating unknown time-varying phases, accurately estimating phases, and sensitively perceiving phase changes pose challenges, demanding the system to continuously remain at the appropriate working range. To address this issue, we propose a neural network-based adaptive weak measurement scheme via single-channel light intensity detection. Through machine learning calibrating the experimental system, the reference phase can be dynamically and accurately adjusted, accommodating time-varying phase changes and ensuring the system operates optimally. Compared with traditional dual-channel weak measurement systems, the scheme reduces experimental complexity. Meanwhile, by accurately adjusting the reference phase, the scheme has higher sensitivity and estimation precision compared to the non-modulated scheme. We validate the effectiveness of the scheme in estimating the period and stochastic time-varying phase. The proposed method highlights the advancement of machine learning in weak measurement systems and can also be applied to other quantum-enhanced measurement schemes.

Optical attenuator-oriented quantum hacking on continuous-variable quantum key distribution with local local oscillator

Continuous-variable quantum key distribution with local local oscillator (LLO-CVQKD) eliminates the security loophole caused by transmitting high power local oscillator (LO). However, in order to establish a common phase frame between the sender and receiver, a low power phase reference needs to be transmitted with quantum signals, which may bring in new security problems for eavesdroppers to obtain information illegally. Especially in trusted phase noise model, phase noise associated with detectors is regarded as trusted noise in order to obtain a higher secret key rate and transmission distance, which further provides opportunities for eavesdroppers. To this end, we propose an optical attenuator-oriented attack strategy against the LLO-CVQKD system under the trusted phase noise model, where Eve can inject suitable light into the optical attenuator in reference light path to reduce the attenuation level of it, thereby controlling the intensity of the reference pulses and resulting in an underestimated excess noise. Simulation results show that the proposed attack strategy can render the estimated secret key rate much higher than the actual values. When the transmission distance exceeds 25 km, the eavesdropper can obtain approximately 90% of the key information by adjusting the intensity of the reference pulses to twice the original value.

Is the dynamical quantum Cheshire cat detectable?

We explore how one might detect the dynamical quantum Cheshire cat proposed by Aharonov et al We show that, in practice, we need to bias the initial state by adding/subtracting a small probability amplitude (‘field’) of the orthogonal state, which travels with the disembodied property, to make the effect detectable (i.e. if our initial state is |↑z⟩ , we need to bias this with some small amount δ of state |↓z⟩ ). This biasing, which can be done either directly or via weakly entangling the state with a pointer, effectively provides a phase reference with which we can measure the evolution of the state. The outcome can then be measured as a small probability difference in detections in a mutually unbiased basis, proportional to this biasing δ. We show this is different from counterfactual communication, which provably does not require any probe field to travel between sender Bob and receiver Alice for communication. We further suggest an optical polarisation experiment where these phenomena might be demonstrated in a laboratory.

Phase response constrained symbol‐level waveform design for dual‐functional radar‐communication systems

AbstractIn this letter, a novel algorithm is proposed to design symbol‐level waveform for dual‐functional radar‐communication (DFRC) systems with low range sidelobe. Different from current schemes design waveform at the block level, a phase response constraint is introduced at the symbol level to provide an additional degree of freedom to decrease the range sidelobe in the pulse compression procedure, which is highly desired in radar systems. In particular, the phase response at the target direction is constrained to be similar to the given reference phase, and the matching error between the designed beampattern and the desired one is minimized subject to the constant modulus constraint. Furthermore, to guarantee the quality of service for communication, constructive interference is exploited at the symbol level for each communication user. An alternating direction method of multipliers algorithm is also proposed to solve the resulting nonconvex optimization problem with tractable subproblems solved sufficiently by the manifold optimization and standard quadratic problem. Numerical simulation results demonstrate the performance of the proposed method.