Harmonic Signature Research Articles

Subcoercive field dielectric response of 0.5(Ba0.7Ca0.3TiO3)-0.5(BaZr0.2Ti0.8O3) thin film: Peculiar third harmonic signature of phase transitions and residual ferroelectricity

Subcoercive field non-linearities in 0.5(Ba0.7Ca0.3TiO3)-0.5(BaZr0.2Ti0.8O3) (BCTZ 50/50) thin film elaborated using pulsed laser deposition are studied using permittivity and phase angle of the third harmonic measurements as a function of the AC measuring field EAC and temperature. The global phase transition temperature Tmax for which the permittivity is maximum, decreases from 330 to 260 K when EAC increases. Rayleigh analysis of the AC field dependence of the relative permittivity shows a regular decrease in the domain wall motion contributions as temperature increases up to Tmax and an even more pronounced decrease above Tmax. This measurement reveals that the ferroelectric behavior subsists 70 K above the global phase transition. The phase angle of the third harmonic at temperatures below 275 K is characteristic of a conventional ferroelectric and from 275 K to Tmax=330 K of a relaxor. Above Tmax, the thin film exhibits a peculiar phase angle of the third harmonic, which consists of −180°→−225°→+45°→0° instead of the −180°→−90°→0° found for relaxor. This peculiar behavior is observed only on heating and is tentatively attributed to changes in the correlations between polar nanoregions.

Gender and ethnicity classification of the 3D nose region based on scaling invariant harmonic wave kernel signature

Gender and ethnicity classification of the 3D nose region based on scaling invariant harmonic wave kernel signature

Narrowband Passive RF Tags for Frequency-Selective Harmonic Doppler Radar Tracking

A design for frequency-selective radio frequency (RF) harmonic tags for harmonic Doppler radar tracking is presented. Harmonic RF tags receive an incident microwave signal and generate a retransmitted signal at a harmonic of the incident frequency, typically the second harmonic. Since environmental backscatter occurs at the fundamental frequency, the second harmonic can be easier to detect. Typical harmonic tags operate over a reasonably wide fractional bandwidth, and thus to detect multiple tags within the same field of view, additional circuitry must generally be added to the tag to differentiate the responses. We propose a different approach based on frequency selectivity implemented by the tag antenna. Based on narrowband split-ring printed antennas, the tags accept incident signals over a specified narrow fractional bandwidth, after which the second harmonic is generated by a diode and retransmitted with a standard dipole antenna. The narrowband filtering occurs at the fundamental frequency antenna, and thus with tags designed at adjacent narrowband frequency channels, no additional circuitry is necessary to differentiate multiple tags. Fabricated tags achieved fractional bandwidths below 0.5% at carrier frequencies below 2.5 GHz while maintaining gains above 2 dBi. The construction of the tag is simple and low-cost, requiring only a single component (a diode) on a printed antenna structure. We demonstrate the feasibility of simultaneously measuring the time-varying harmonic Doppler signature of multiple tags in the field of view by experimentally verifying the frequency selectivity of tags in motion using a 2.4/4.8 GHz harmonic Doppler radar.

Distributed harmonic patterns of structure-function dependence orchestrate human consciousness

A central question in neuroscience is how consciousness arises from the dynamic interplay of brain structure and function. Here we decompose functional MRI signals from pathological and pharmacologically-induced perturbations of consciousness into distributed patterns of structure-function dependence across scales: the harmonic modes of the human structural connectome. We show that structure-function coupling is a generalisable indicator of consciousness that is under bi-directional neuromodulatory control. We find increased structure-function coupling across scales during loss of consciousness, whether due to anaesthesia or brain injury, capable of discriminating between behaviourally indistinguishable sub-categories of brain-injured patients, tracking the presence of covert consciousness. The opposite harmonic signature characterises the altered state induced by LSD or ketamine, reflecting psychedelic-induced decoupling of brain function from structure and correlating with physiological and subjective scores. Overall, connectome harmonic decomposition reveals how neuromodulation and the network architecture of the human connectome jointly shape consciousness and distributed functional activation across scales.

Far-Wake Meandering of a Wind Turbine Model with Imposed Motions: An Experimental S-PIV Analysis

Intra-array wake meandering increases fatigue loading in downstream turbines and decreases farm total power output. In the case of floating offshore wind turbines (FOWTs), the motions of the floating substructure could have a non-neglectable contribution to wake meandering dynamics. This research experientially analyses the influence of imposed motions on the far-wake meandering of a FOWT. The study considers a 1:500 scaled porous disc representation of the 2 MW FLOATGEN system (BW Ideol) located off the coast of Le Croisic, France. A representative marine neutral atmospheric boundary layer is generated in a wind tunnel whilst monochromic and multi-frequency content three degrees of freedom (surge, heave, pitch) motion is imposed on the model tower. The stereoscopic particle image velocimetry (S-PIV) is then utilised to measure velocity vectors at a cross-section located at 8.125 D downstream of the model. No significant effect on the far-wake recovery in the velocity, turbulence and turbulent kinetic energy distribution is observed. However, the frequency characteristics of the imposed motions were observed in the far-wake meandering spectral content and streamwise characteristics of far-wake, such as normalised available power. While the frequency spectrum of the vertical oscillations showed more sensitivity to the three degrees of freedom (3DoF) imposed motion in all frequency ranges, the lateral oscillation was sensitive for the reduced frequency above 0.15. The monochromic motions with a reduced frequency of less than 0.15 also did not influence the far-wake centre distribution in both lateral and vertical directions. Regardless of reduced frequency, imposed motions show a strong effect on average power, in which the harmonic signature can distinguish in far-wake memory. This study provides an investigation, which its result could be beneficial to developing and examining wake models for offshore wind turbines, with a particular focus on the influence of FOWTs motions.

Nonlinear Characterization of Waveguide Index Profile: Application to Soft-Proton-Exchange in LiNbO$_3$

In integrated photonics, the precise knowledge of the waveguides refractive index profile is mandatory for the modeling of photonic chips and therefore implementing innovative circuits. Usual index profile determination relies on effective index measurement of propagating modes in planar waveguides coupled with numerical fitting tools. In this paper we propose an alternative technique based on the characterization of the second harmonic generation signature of a nonlinear waveguide. We include the characterization of high-order spatial modes showing their relevance to probe both vertical and lateral distributions. We finally provide an explicit profile ready-to-use for modeling soft-proton exchanged waveguides in lithium niobate and we test its prediction capability.

Adaptive Single-Pole Auto-Reclosing Scheme Based on Secondary Arc Voltage Harmonic Signatures

This paper presents an advanced adaptive single-pole auto-reclosing (ASPAR) scheme based on harmonic characteristics of the secondary arc voltage. For analysis of the harmonics, short-time Fourier transform (STFT), which is a universal signal processing tool for transforming a signal from the time domain to the frequency domain, is utilized. STFT is applied to extract the abnormal harmonic signature from the voltage waveform of a faulted phase when a transient or permanent fault occurs on a power transmission line. The proposed scheme uses the total harmonic distortion (THD) factor to determine the fault type based on the variation and distortion characteristics of the harmonics. Harmonic components in the order of odd/even are also utilized to detect the secondary arc extinction time and guide the reclosing operation. Based on these factors, two coordinated algorithms are proposed to reduce the unnecessary dead time in conventional auto-reclosing methods and enable an optimal reclosing operation in the event of a single-pole to ground fault. The proposed ASPAR scheme is implemented using the electromagnetic transient program (EMTP), and various simulations are conducted for actual 345 and 765 kV Korean study systems.

Harmonics from a magic carpet

Abstract

An Improved Load Feature Extraction Technique for Smart Homes Using Fuzzy-Based NILM

With the advancement of smart residential buildings, houseowners are increasingly interested to monitor the connected electrical loads in view of energy conservation and load management. Smart grid technology in the distribution system includes cutting-edge load monitoring applications, permitting efficient use of electrical energy. Nonintrusive load monitoring (NILM) technique is such a tool to recognize the consumption of energy for individual electrical loads in a residential system at a solitary point of measurement. In this article, an improved NILM method is proposed using a shunt passive filter installed at the source end of residential building with the help of current harmonic signature analysis. A fuzzy rule-based intelligent identification method is employed in order to detect and monitor different electrical loads considering various load features at the utility side. The major contribution of the proposed technique is the improvement in identification accuracy of household loads with multiple appliances. The connected filter additionally restricts the injected harmonics generated by the loads at the source end. The usage of the fuzzy technique also reduces the processor memory requirement than conventional machine learning techniques. Simulations backed by experimental results validate the viability of the proposed methodology.

3D skull and face similarity measurements based on a harmonic wave kernel signature

Research regarding the similarity measurements of 3D craniofacial models (including 3D skull and face models) is an important research direction in fields such as archaeology, forensic science, and anthropology and represents a meaningful and challenging task. Its major challenges are the fact that 3D skulls are geometric models with multiple holes and complex topologies, there are facial expression changes on the 3D faces. Therefore, the general 3D shape similarity measurements, which are sensitive to boundaries and expression changes, make it impossible to simultaneously measure skull and face similarity. In this paper, we define a 3D signature to describe the pure intrinsic structure and distinguish the similar basic shape and complex topology of 3D skulls and faces: the harmonic wave kernel signature (HWKS). The HWKS is a point descriptor involving the Laplace–Beltrami operator, which is able to effectively extract geometrical and topological information from 3D skulls and faces. Based on the HWKS, we provide an effective pipeline for 3D skull and face similarity measurement by calculating the cosine distance between the HWKS values of 3D skulls and faces. By making comparisons with the wave kernel signature, the HWKS simultaneously describes both local and global properties of a shape. Results from a number of experiments have already shown that our framework is suitable for both measure 3D skull similarity and face similarity, and more importantly, measuring skull similarity and face similarity are two independent processes although using the same framework. By using the same measurement method for 3D skull similarity and face similarity, we observe an effective craniofacial relationship under unified metrics: The change rate of skull similarity is generally consistent with the corresponding face similarity, indicating the correlation between the shape of the 3D skull and its corresponding 3D face shape. And our experimental results show the rationality and effectiveness of this method, which refers to the previous researchers measure the similarity of the reconstructed face from the original skull to reflect the similarity of the original skull.

Adaptive Intrawell Matched Stochastic Resonance with a Potential Constraint Aided Line Enhancer for Passive Sonars.

Remote passive sonar detection and classification are challenging problems that require the user to extract signatures under low signal-to-noise (SNR) ratio conditions. Adaptive line enhancers (ALEs) have been widely utilized in passive sonars for enhancing narrowband discrete components, but the performance is limited. In this paper, we propose an adaptive intrawell matched stochastic resonance (AIMSR) method, aiming to break through the limitation of the conventional ALE by nonlinear filtering effects. To make it practically applicable, we addressed two problems: (1) the parameterized implementation of stochastic resonance (SR) under the low sampling rate condition and (2) the feasibility of realization in an embedded system with low computational complexity. For the first problem, the framework of intrawell matched stochastic resonance with potential constraint is implemented with three distinct merits: (a) it can ease the insufficient time-scale matching constraint so as to weaken the uncertain affect on potential parameter tuning; (b) the inaccurate noise intensity estimation can be eased; (c) it can release the limitation on system response which allows a higher input frequency in breaking through the large sampling rate limitation. For the second problem, we assumed a particular case to ease the potential parameter . As a result, the computation complexity is greatly reduced, and the extremely large parameter limitation is relaxed simultaneously. Simulation analyses are conducted with a discrete line signature and harmonic related line signature that reflect the superior filtering performance with limited sampling rate conditions; without loss of generality of detection, we considered two circumstances corresponding to (periodic signal with noise) and (pure noise) hypotheses, respectively, which indicates the detection performance fairly well. Application verification was experimentally conducted in a reservoir with an autonomous underwater vehicle (AUV) to validate the feasibility and efficiency of the proposed method. The results indicate that the proposed method surpasses the conventional ALE method in lower frequency contexts, where there is about 10 dB improvement for the fundamental frequency in the sense of power spectrum density (PSD).

Acoustic recordings and modeling under seasonally varying sea ice

Acoustic data from the Canada Basin Acoustic Propagation Experiment are discussed. These recordings were obtained under seasonally varying sea ice to the north of Alaska during a period of 154 days. They contain signals from sources that were deployed at ranges of 17.5, 29.6, and 237.8 km and ambient sounds from marine mammals and ice-related events. After the area was covered with ice, the amplitude of receptions from the most distant source gradually decreased as scattering features on the underside of the ice developed during fracturing, drifting, ridging, and rafting events. Improvements are presented for an Arctic acoustic model that is based on the parabolic equation method, and the approach is applied to a problem in which variable ice thickness acts as a loss mechanism by scattering energy out of the waveguide. Some of the recordings have a harmonic signature that is believed to be associated with the resonances of ice floes rubbing together, but variations in the harmonics over short time scales cannot be explained in terms of the resonances of an isolated floe. This behavior may be related to the coupling of vibrations at contact points that vary during the relative motions of floes.

A Diagnostic Analytics of Harmonic Source Signature Recognition by Using Periodogram

<span lang="EN-GB">This paper presents a diagnostic analytics of harmonic source signature recognition of rectifier and inverter-based load in the distribution system with single-point measurement at the point of common coupling by utilizing Periodogram. Signature recognition pattern is used to distinguish the harmonic sources accurately by obtaining the distribution of harmonic and interharmonic components and the harmonic contribution changes. This is achieved by using the significant signature recognition of harmonic producing load obtained from analysing the harmonic contribution changes. </span><span>Based on voltage and current signature analysis, the distribution of harmonic components can be divided into three zones. To distinguish between the harmonic producing loads, the harmonic components are observed at these zones to get the signature recognition pattern.</span><span lang="EN-GB"> The result demonstrate that periodogram technique accurately diagnose and distinguish the type of harmonic sources in the distribution system.</span>

Flash focus ultrasonic images sequences for shear shock wave observation in the brain

Nonlinear shear waves have a cubic nonlinearity which results in the generation of a unique characteristic odd harmonic signature. This behavior was first observed in a homogeneous gelatin phantom using ultrafast plane wave ultrasound imaging and a correlation-based tracking algorithm to determine particle motion. However, in heterogeneous tissue, like brain, the heterogeneities generate clutter that degrades motion tracking to the point where the shock waves and their characteristic odd harmonics are no longer observable. We present a high frame-rate ultrasound imaging sequence consisting of multiple focused emissions that improves the image quality and reduces clutter to generate high quality motion estimates of shear shock waves propagating in the brain. A point spread function analysis is used to characterize the improvements of the proposed imaging sequence. It is shown that the flash focus sequence reduces the side lobes by 20 dB while retaining the same spatial resolution translating to a sensitivity up to the 11th harmonic. The flash focus sequence are then used to acquire high frame-rate (6500 fps) ultrasound movies of an ex-vivo porcine brain in which a shear wave propagates. Using an adaptive tracking algorithm, we compute the particle velocity in a field of view as deep as the brain. It is therefore demonstrated that the proposed method can detect the nonlinear elastic motion and the odd harmonics with sufficient sensitivity to observe the development of a shear wave into a shock wave as it propagates in the brain.

Impact of inclination on quasi-periodic oscillations from spiral structures

Context. Quasi-periodic oscillations (QPOs) are a common feature of the power spectrums of X-ray binaries. Currently it is not possible to unambiguously differentiate the large number of proposed models to explain these phenomena through existing observations. Aims. We investigate the observable predictions of a simple model that generates flux modulation: a spiral instability rotating in a thin accretion disk. This model is motivated by the accretion ejection instability (AEI) model for low- frequency QPOs (LFQPOs). We are particularly interested in the inclination dependence of the observables that are associated with this model. Methods. We develop a simple analytical model of an accretion disk, which features a spiral instability. The disk is assumed to emit blackbody radiation, which is ray-traced to a distant observer. We compute pulse profiles and power spectra as observed from infinity. Results. We show that the amplitude of the modulation associated with the spiral rotation is a strong function of inclination and frequency. The pulse profile is quasi-sinusoidal only at low inclination (face-on source). As a consequence, a higher-inclination geometry leads to a stronger and more diverse harmonic signature in the power spectrum. Conclusions. We present how the amplitude depends on the inclination when the flux modulation comes from a spiral in the disk. We also include new observables that could potentially differentiate between models, such as the pulse profile and the harmonic content of the power spectra of high-inclination sources that exhibit LFQPOs. These might be important observables to explore with existing and new instruments.

A NEW METHOD FOR DETECTION OF UNBALANCE VOLTAGE SUPPLY IN THREE PHASE INDUCTION MOTOR

Induction motors are associated with various techno-economic advantages; therefore these are widely used in residential, commercial and industrial systems. Cost effective and reliable process of condition monitoring of induction motor is very important. It is found that unbalance voltage supply is one of the major factors that produce uneven heating due to reverse current and leads to inter-turn short circuit. The issue regarding unbalanced voltage supply has attracted the attention of researcher and engineers in recent past. In this paper, a new effective non-invasive (online) method is proposed that only use rotor harmonic current signature for the detection of unbalance voltage supply instead of main line current signature. This is a sensor-less and online approach that accomplishes the reliable and accurate analysis of the induction motors. Moreover, it allows a continuous real time tracking without disturbing the normal operation and guarantees the overall production process. Additionally, this method recognizes the unbalance and estimate the severity of the unbalance in the voltage source. The effects of unbalance voltage supply are investigated through experiments. In order to perform the analysis and detect the asymmetry due to unbalance voltage, an experimental set up is designed that can accurately repeat the measurements. In the proposed work, unbalance voltage supply is diagnosed through experimental hardware setup. To validate the propose methods an experiment is performed that confirm that motor operating under unbalance voltage supply give a significant rise in the rotor harmonic while under balance voltage supply there is so such a rise in the rotor harmonic.

Single-Phase Transformer Harmonics Produced During Geomagnetic Disturbances: Theory, Modeling, and Monitoring

The main purpose of this paper is to provide a methodology to monitor harmonics produced by power transformers during geomagnetic disturbances. The advocated scheme leverages the existing infrastructure and is based on the embedded operating quantities of microprocessor-based differential protection relays. The characteristics of single-phase transformer magnetizing current are discussed. The second harmonic signature is a good indicator of half-cycle saturation and can be mapped into an effective geomagnetically induced current. The proposed scheme was tested in closed-loop using a real-time digital simulator and validated with field measurements.

Altruism Displays a Harmonic Signature in Structured Societies

Several parameters combine to govern the nature of agent interactions in evolutionary social simulations. Previous work has suggested that these parameters may have complex interplay that is obscured when they are not analyzed separately. Here we focus specifically on how three population-level parameters, which govern agent interactions, affect levels of altruism in a population. Specifically we vary how frequently agents interact in a generation, how far along a network they may interact, and the size of the population. We show that the frequency with which an agent interacts with its neighbors during a generation has a strong effect on levels of evolved altruism – provided that those pairings are stochastic. When agents interact equally with all of their neighbors, regardless of how often, minimal levels of altruism evolve. We further report a curious harmonic signature in the level of altruism resulting from the interplay of the benefit-cost ratio of an altruistic act and the number of agent interactions per generation. While the level of altruism is generally an increasing function of the number of pairings per generation, at each instance where pairings equals a multiple of the benefit-cost ratio a sharp discontinuity occurs, precipitating a drop onto a lower-value function. We explore the nature of these discontinuities by examining the temporal dynamics and spatial configuration of agents. Finally, we show that rules for the evolution of cooperation that are based on network density may be inadvertently missing effects that are due to the frequency of interactions and whether those interactions are symmetrical among neighbors.

Voltage harmonic content of long artificially generated electrical arc in out-door experiment at 500 kV towers

This study involves the application of Short Time Discrete Fourier Transform in order to obtain the harmonic content of voltage between the terminals of 647 artificially generated long electrical arcs. Non-confined tests were conducted on three 500 kV towers specially built inside a laboratory facility, in order to represent as close as possible actual transmission line conditions. The 1-s duration arcs were artificially generated along the 4 m insulator string of a 500 kV tower by imposing a sustained 60 Hz current. The arc voltage harmonic content can be used to identify the moment at which the arc is stabilized in the air and only after this instant measured data can be used to derive mathematical arc model. A statistical analysis of the results, considering only the period for which the arc is stabilized, enabled the establishment of the harmonic signature of the electric arcs for a large arc current amplitude range. From the results it can be stated that an accurate arc model should properly reproduce the presented harmonic content for any arc current level.

Measurement of 40 power system harmonics in real‐time on an economical ARM ® Cortex™‐M3 platform

Within future homes and electrical power networks, emphasis is being placed on intelligent, distributed measurement devices. In particular, the recognition of individual or aggregated loads through harmonic signature has been proposed as a useful way to enhance the value of home energy monitoring/control. Clearly, the cost of implementing such measurement devices is a major barrier to acceptance. In a recent project, a challenge was set to implement real-time software on an ARM® Cortex™ LPC1768 microcontroller platform (chip cost c. £4). The software must be capable of measuring a single-phase AC frequency, real and reactive power flows and provide a full breakdown of the voltage and current (and power) behaviour via harmonic analysis from DC to the 40th, in real-time with a new output every 20 ms. In addition, the algorithm must be capable of adapting the measurement when the frequency is not nominal (50 Hz) so that spectral leakage is minimised. It is found that the LPC1768 processor is capable of supporting such an algorithm when it is coded appropriately. This knowledge de-risks the proposed use of such cheap microcontrollers for these relatively complex tasks.