High Sampling Rate Research Articles

Artificial Intelligence Based Optimal Placement of PMU

The investigation of power system disturbances is critical for ensuring the supply’s dependability and security. Phasor Measurement Unit (PMU) is an important device of our power network, installed on system to enable the power system monitoring and control. By giving synchronised measurements at high sample rates, Phasor Measurement Units have the potential to record quick transients with high precision. PMUs are gradually being integrated into power systems because they give important phasor information for power system protection and control in both normal and abnormal situations. Placement of PMU on every bus of the network is not easy to implement, either because of expense or because communication facilities in some portions of the system are limited. Different ways for placing PMUs have been researched to improve the robustness of state estimate. The paper proposes unique phasor measurement unit optimal placement methodologies. With full network observability, the suggested methods will assure optimal PMU placement. The proposed algorithm will be thoroughly tested using IEEE 7, 9, 14, and 24 standard test systems, with the results compared to existing approaches.

Fast Algorithms for Estimating the Disturbance Inception Time in Power Systems Based on Time Series of Instantaneous Values of Current and Voltage with a High Sampling Rate

The study examines the development and testing of algorithms for disturbance inception time estimation in a power system using instantaneous values of current and voltage with a high sampling rate. The algorithms were tested on both modeled and physical data. The error of signal extremum forecast, the error of signal form forecast, and the signal value at the so-called joint point provided the basis for the suggested algorithms. The method of tuning for each algorithm was described. The time delay and accuracy of the algorithms were evaluated with varying tuning parameters. The algorithms were tested on the two-machine model of a power system in Matlab/Simulink. Signals from emergency event recorders installed on real power facilities were used in testing procedures. The results of this study indicated a possible and promising application of the suggested methods in the emergency control of power systems.

Performance Analysis of Electromyogram Signal Compression Sampling in a Wireless Body Area Network.

The rapid growth in demand for portable and intelligent hardware has caused tremendous pressure on signal sampling, transfer, and storage resources. As an emerging signal acquisition technology, compressed sensing (CS) has promising application prospects in low-cost wireless sensor networks. To achieve reduced energy consumption and maintain a longer acquisition duration for high sample rate electromyogram (EMG) signals, this paper comprehensively analyzes the compressed sensing method using EMG. A fair comparison is carried out on the performances of 52 ordinary wavelet sparse bases and five widely applied reconstruction algorithms at different compression levels. The experimental results show that the db2 wavelet basis can sparse EMG signals so that the compressed EMG signals are reconstructed properly, thanks to its low percentage root mean square distortion (PRD) values at most compression ratios. In addition, the basis pursuit (BP) reconstruction algorithm can provide a more efficient reconstruction process and better reconstruction performance by comparison. The experiment records and comparative analysis screen out the suitable sparse bases and reconstruction algorithms for EMG signals, acting as prior experiments for further practical applications and also a benchmark for future academic research.

Frequency-Modulated Signal Measurement Using Closed-Loop Methodology.

Frequency-modulated (FM) signals are widely used in sensing, measurement, and signal detection due to their strong anti-interference and easy transmission characteristics. Although the high-precision measurement methods for static signals are quite complete, the high-precision measurement methods for dynamic FM signals still need to be studied, and the measurement accuracy in the high-sampling system still has room for improvement. Traditionally, the equal-precision measurement method is widely applied in most scenarios. However, its accuracy is limited by the quantization error of ±1 word and the sampling gate time, making it difficult to improve the frequency measurement accuracy while ensuring a high sampling rate at the same time. In this paper, a high-precision feedback frequency measurement system with the capability to eliminate the quantization error of ±1 word is proposed. The proposed system consists of two stages, the rough measurement stage based on the equal-precision measurement method and the precise measurement stage based on the negative feedback tracking architecture using the phase–frequency detector (PFD) and direct digital synthesizer (DDS). The effectiveness and feasibility of the system are verified by both simulation and experiment. At the sampling rate of 2 kHz, the frequency measurement accuracy is improved by more than 30 dB.

A 1.5-GS/s 6-bit Single-Channel Loop-Unrolled SAR ADC With Speculative CDAC Switching Control Technique in 28-nm CMOS

This paper presents a 1.5-GS/s 6-bit single-channel loop-unrolled successive approximation register (SAR) analog-to-digital converter (ADC) using speculative capacitive DAC (CDAC) switching control technique. The proposed SAR ADC achieves a high sampling rate by eliminating additional delays in typical loop-unrolled SAR ADCs related to settling time constraints in their CDACs. Specifically, the CDACs are duplicated and controlled in speculative ways so that the CDAC outputs passage to their next values before completing the regeneration operation of comparators, thereby improving timing constraints for successive approximations. The switching power overhead from the CDAC speculation is mitigated by introducing an energy-efficient CDAC control technique that produces desired voltage transients with minimal power overheads. The prototype of the proposed SAR ADC is fabricated in a 28-nm CMOS technology and occupies an active area of 0.0038-mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The design consumes 5.8 mW from a 1.2-V supply. The ADC achieves 1.5-GS/s sampling frequency with a 31-dB SNDR at a low input frequency and a 28.6 dB at the Nyquist frequency without applying any offset calibration techniques, achieving the highest sampling frequency among the 6-bit single-channel loop-unrolled SAR ADCs reported.

Measurement error analysis and accuracy improvement method based on gateway meter

As the accuracy of the gateway meter is affected by various disturbances, it is necessary to analyze those influence factors intuitively. This paper introduces the main factors affecting the measurement accuracy and further proposes the improvement methods of the gateway meter. The influence factors are mainly on the aspects of the analog circuit, temperature, harmonics and ADC (Analog-to-Digital Converter), which will cause certain measurement error during the operation process of the gateway meter. Thus, the corresponding methods such as using high sampling rate of ADC and choosing appropriate voltage range are suggested to use. This paper provides a certain basis for improving the accuracy and reliability of the gateway meter.

UAV magnetometer survey in low‐level flight for archaeology: Case study of a Second World War airfield at Ganacker (Lower Bavaria, Germany)

AbstractUnmanned aerial vehicle (UAV)‐based magnetometer systems became more and more attractive for large‐scale archaeological prospection in recent years. Although their sensors exhibit the same sensitivity than the ground‐based prospecting systems, UAV prospecting is seriously handicapped by the magnetic and mechanical disturbances of the drone and by limitations of a low‐level flight. To minimize these disturbances, scalar magnetometers are attached only on a tether 2.5–10 m beneath the drone to be flown as close as possible above the ground. First, test measurements with UAV‐fixed fluxgate magnetometers provide more accurate results than the scalar magnetometers in any configuration but have to overcome disturbance by vibrations. Here, we present a case study choosing the compact set‐up of the Sensys MagDrone R4. The high sampling rate of 200 Hz of the three axis fluxgate sensors of the R4 allows sufficient filtering of the interferences generated by the UAV and external disturbances. High‐precision flight control of the drone allows operating the sensors by radar‐controlled flight height ∼1 m above the ground, which is a fundamental and indispensable prerequisite for archaeological prospecting. For our test, we choose the site Ganacker (southern Bavaria), where we expected a large range of archaeological structures and features with high magnetic contrast. We compare and verify the magnetogram with historical and recent geodata. Our results show that the R4 system offers an outstanding step forward regarding a successful application for archaeological prospection. Already now, the system is well suited for the fast mapping of large areas and archaeological sites with intense magnetic anomalies.

Forecasting the success of the WEAVE Wide-Field Cluster Survey on the extraction of the cosmic web filaments around galaxy clusters

ABSTRACT Next-generation wide-field spectroscopic surveys will observe the infall regions around large numbers of galaxy clusters with high sampling rates for the first time. Here, we assess the feasibility of extracting the large-scale cosmic web around clusters using forthcoming observations, given realistic observational constraints. We use a sample of 324 hydrodynamic zoom-in simulations of massive galaxy clusters from TheThreeHundred project to create a mock-observational catalogue spanning 5R200 around 160 analogue clusters. These analogues are matched in mass to the 16 clusters targetted by the forthcoming WEAVE Wide-Field Cluster Survey (WWFCS). We consider the effects of the fibre allocation algorithm on our sampling completeness and find that we successfully allocate targets to 81.7 ${\rm {per \,cent}}\, \pm$ 1.3 of the members in the cluster outskirts. We next test the robustness of the filament extraction algorithm by using a metric, Dskel, which quantifies the distance to the filament spine. We find that the median positional offset between reference and recovered filament networks is Dskel = 0.13 ± 0.02 Mpc, much smaller than the typical filament radius of ∼ 1 Mpc. Cluster connectivity of the recovered network is not substantially affected. Our findings give confidence that the WWFCS will be able to reliably trace cosmic web filaments in the vicinity around massive clusters, forming the basis of environmental studies into the effects of pre-processing on galaxy evolution.

A Modulated Wideband Converter Model Based on Linear Algebra and Its Application to Fast Calibration.

In the context of cognitive radio, smart cities and Internet-of-Things, the need for advanced radio spectrum monitoring becomes crucial. However, surveillance of a wide frequency band without using extremely expensive high sampling rate devices is a challenging task. The recent development of compressed sampling approaches offers a promising solution to these problems. In this context, the Modulated Wideband Converter (MWC), a blind sub-Nyquist sampling system, is probably the most realistic approach and was successfully validated in real-world conditions. The MWC can be realized with existing analog components, and there exist calibration methods that are able to integrate the imperfections of the mixers, filters and ADCs, hence allowing its use in the real world. The MWC underlying model is based on signal processing concepts such as filtering, modulation, Fourier series decomposition, oversampling and undersampling, spectrum aliasing, and so on, as well as in-flow data processing. In this paper, we develop an MWC model that is entirely based on linear algebra, matrix theory and block processing. We show that this approach has many interests: straightforward translation of mathematical equations into simple and efficient software programming, suppression of some constraints of the initial model, and providing a basis for the development of an extremely fast system calibration method. With a typical MWC acquisition device, we obtained a speed-up of the calibration computation time by a factor greater than 20 compared with a previous implementation.

Dynamic and precise long-distance ranging using a free-running dual-comb laser.

Long-distance ranging is a crucial tool for both industrial and scientific applications. Laser-based distance metrology offers unprecedented precision making it the ideal approach for many deployments. In particular, dual-comb ranging is favorable due to its inherently high precision and sampling rate. To make high-performance long-range dual-comb LiDAR more accessible by reducing both cost and complexity, here we demonstrate a fiber-based dual-comb LiDAR frontend combined with a free-running diode-pumped solid-state dual-comb laser that allows for sub-µm measurement precision while offering a theoretical ambiguity range of more than 200 km. Our system simultaneously measures distance with the role of each comb interchanged, thereby enabling Vernier-based determination of the number of ambiguity ranges. As a proof-of-principle experiment, we measure the distance to a moving target over more than 10 m with sub-µm precision and high update rate, corresponding to a relative precision of 10-7. For a static target at a similar distance, we achieve an instantaneous precision of 0.29 µm with an update time of 1.50 ms. With a longer averaging time of 200 ms, we reach a precision of around 33 nm, which corresponds to a relative precision of about 3·10-9 with a time-of-flight-based approach.

Compressed and Encrypted Acquisition of Transient Signals

A shockwave signal has the characteristics of short duration and wide dynamic range, so the wireless test system needs to collect it at a continuous high sampling rate, resulting in a short node life cycle and a large amount of redundant data during the test process. Moreover, test data with confidentiality, if it is still recorded and transmitted in plaintext, will challenge information security. Therefore, a compressed and encrypted acquisition framework based on hyperchaotic compressed sensing and semi-tensor is proposed in this paper. Firstly, a new four-dimensional hyperchaotic system is used to generate a compressed sensing measurement matrix to improve the encryption and anti-noise performance. Secondly, for saving memory space and improving computing efficiency, the semi-tensor product is introduced to reduce the dimension of the measurement matrix exponentially. The experimental results show that the proposed framework can realize the compressed and encrypted acquisition of transient signals with small memory space and low computational complexity. And the acquisition results can be directly transmitted to meet the requirements of real-time wireless transmission bandwidth and information security.

New impedance bridge at LNE for the two terminal-pair AC resistor calibration up to 20 kHz

This paper presents the evolution of LNE’s impedance bridge (Wheatstone bridge) used to calibrate AC resistors defined in the two terminal-pair configuration. A new automated Wheatstone bridge, based on four resistances, was developed to operate in the full complex plane for resistances ranging from 400 Ω to 2 MΩ and for frequencies up to 20 kHz. A commercial dual precision arbitrary waveform generator supplies the bridge and PXI modules achieve the balance. Phase and frequency synchronization solutions between the arbitrary waveform generator source and the PXI modules were used. The choice of these instruments allows the bridge to be easily automated and to benefit from recent progress in the development of digital-analog converters, in particular those with high frequency sampling rates and resolution. The bridge is mainly dedicated to realize the periodic calibration of LNE’s standard resistors, used for routine customer calibrations. The traceability of LNE’s standard resistors is ensured, firstly, by the calibration of a 1 kΩ resistor by comparison to a calculable resistor up to 20 kHz. Then, this resistor is used as a reference element to ensure the traceability of all LNE’s standard resistors using the new bridge. The validation was done by comparing the results obtained, for some resistors with very low drift, with those obtained during calibrations performed in 1983, 1995 and 2009. For resistors of 1 kΩ in a 1:1 ratio, the expanded uncertainty of series resistance variation and argument are, respectively, less than 1.3 µΩ Ω−1 (k = 1) and 1.2 µrad (k = 1), up to 20 kHz.

Compressor Surge Precursors for a Turbocharger Coupled to a Pressure Vessel

Abstract Dynamic compressors operating region is mainly constrained by fluid-dynamic instabilities occurring at low mass flow rate conditions, such as surge and rotating stall. This work presents a vibro-acoustic experimental investigation on a centrifugal compressor of an automotive turbocharger aimed to identify and confirm some surge precursor values in correspondence of its inception conditions. The experimental campaign was carried out on a turbocharger equipped by a vaneless diffuser compressor exploited for the pressurization of an innovative solid oxide fuel cell (SOFC) emulator. The investigated turbocharger is coupled with a pressure vessel for a former emulation activity on a pressurized SOFC. In such kind of plants, the joint effect of large volume size downstream the compressor makes more complex the dynamic behavior of the whole system during transients, thus significantly increasing surge onset risk. The main goal is to define a suitable quantitative indicator to detect in advance surge inception by relying only on system vibro-acoustic response. Several transient from a compressor stable condition to surge instability onset were performed by progressively closing specific valves in the air line. When moving close to surge , vibro-acoustic signals were acquired at a high sampling rate to investigate blade passage phenomena which might interact with rotating stall inception. Meanwhile, pressures, temperatures and mass flow rates measured at a lower sampling rate to correlate compressor vibro-acoustic and performance behavior. Cyclostationary analysis was performed on vibro-acoustic acquired signals to provide innovative diagnostic and predictive solutions (precursors) for early surge detection.

Digital sampling of acoustic impulse noise: Implications for exposure measurement and damage risk criteria.

Current standards for the measurement of impulse noise (e.g., MIL-STD-1474E) recommend using a sampling rate of at least 200 kHz in order to accurately estimate the risk of hearing damage. The given motivation for this high sampling rate is to ensure a temporal resolution in the impulse waveform fine enough to accurately capture the peak pressure. However, the Nyquist-Shannon sampling theorem specifies that a sampled signal can accurately reconstruct both the amplitude and phase information of a signal given the sampling rate is at least twice the highest frequency present in the original signal. Thus, it is possible to reconstruct a band limited signal with the same temporal resolution as one captured at a higher sampling rate if the contributions of energy above the Nyquist rate can be ignored. In this study, resampling techniques are applied to a signal sampled at 48 kHz to extract A-weighted sound pressure energy estimates within 0.1 dB of those obtained at a higher sampling rate. Our results suggest sampling rates for impulsive noise should be based on the range of frequencies expected to make a contribution to injury risk rather than on concerns about temporal resolution.

High-Speed Train Positioning Using Deep Kalman Filter With 5G NR Signals

Positioning is the most basic yet important process in a train control system. In practical train systems, the position of a train is determined with a track circuit, a radio frequency (RF) tag called a “balise”, or a tachometer. A train control center gives each train an automatic train protection (ATP) speed profile computed from the positioning information of both the train and the next train in front it. To successfully operate in a conventional train control system such as ATP/ATO, each train derives its own automatic train operation (ATO) speed profile from the ATP speed profile provided by the control center. However, existing train positioning schemes face many difficulties in terms of installation, maintenance, and repair. To address these difficulties, we consider using 5G NR (New Radio) signals which have a high probability for guaranteeing line-of-sight (LOS) as well as a high sampling rate because they do not require the additional installation of any infrastructure for positioning. In this paper, we propose two positioning schemes for high speed trains (HSTs) based on Kalman filters that make use of 5G NR signals. The first is an HST positioning scheme using a modified Kalman filter and the second is an HST positioning scheme using a deep Kalman filter. Simulation results show that the two proposed schemes achieve better performance in nonlinear non-Gaussian systems as well as in nonlinear Gaussian systems in terms of mean and worst 5% position errors when compared to the existing positioning scheme for HSTs that utilize 5G NR signals.

Performance Measurement and Discharge Data Based Analysis of Ultrasonic Assisted μEDM for Ti6Al4V

Abstract Unconventional machining of difficult-to-cut conductive materials with high accuracy, low heat-affected zone formation, and the ability to cut intricate geometries entitles micro-electrical discharge machining (μEDM) as the most versatile technology in micromachining. Ultrasonic vibration assistance further enhances the material-removing ability of the μEDM process while imparting several other benefits. The present work proposes a comparative study between the unassisted and ultrasonic vibration assisted μEDM to the tool electrode for machining microslots on Ti6Al4V material using an in-house developed tool holder. The characteristics of the discharge waveforms were captured using a data acquisition system at high sampling rates. The pulse discrimination system is used to perform an in-depth study of the discharge pulses. μEDM milling experiments were performed to machine microslots at varying input voltages, capacitances, and feed rates. The ultrasonic vibrations proved beneficial in addressing the primary issue associated with the μEDM process, i.e., the material removal rate (MRR) with a maximum of 35% increment. Applying ultrasonic vibrations reduced the recast layer and tool wear rate (TWR) and increased the surface finish.

Digitalization of asset surveillance through distributed fiber-optic sensing: Geophysics and engineering diagnostics and streaming

Fiber-optic distributed acoustic sensing (DAS) can listen to a wide range of signals. This listening takes place at high sampling rates with fine spatial resolution, resulting in large data volumes. Data streaming solutions are available but result in large transmission and storage costs. In this paper, we describe strategies to convert large data streams from DAS interrogator units to diagnostics or processed products. Optimizing DAS systems results in higher signal-to-noise ratio for signals while extracting diagnostic features out of the noise that could be related to production or well engineering. DAS has sensitivity to diverse signals, and the first goal of edge processing is to separate them for consumption by various disciplines. Focusing the processing on specific aspects in the DAS recordings provides data products that are streamed in efficient ways. We show how DAS processing can deploy fast algorithms so that data diagnostics are sent to remote locations. This enables real-time-diagnostics and event-detection tools. By providing the bulk of computing in the field, data upload to remote servers is efficient and targeted. We show how this managed data stream enables digitalization of engineering and geoscience assets.

Knee Extensor Rate Of Torque Development Assessment Post-acl Reconstruction: Does Sampling Rate Matter?

Impaired quadriceps neuromuscular function is a hallmark of anterior cruciate ligament injury and reconstruction (ACLR). Recent investigations suggest that reduced knee extensor rate of torque development (RTD) is strongly associated with abnormal movement mechanics post-ACLR and persists at or beyond return to sport. RTD is typically quantified at high (≥1000 Hz) sampling rates (SR), which is a barrier to clinical assessment as most clinical equipment features low SR (100 Hz). PURPOSE: To determine how SR influences knee extensor RTD in collegiate athletes near return to sport post-ACLR. METHODS: 35 Division I athletes (age 20.6 ± 1.6 y, BMI 25.0 ± 3.3 kg/m2, 21 female) performed rapid maximal effort isometric knee extension contractions at 9.1 ± 2.5 months post-ACLR on an isokinetic dynamometer. Torque signals were sampled at 2000 Hz. RTD was characterized with multiple variables: from contraction onset to 50, 100, and 200 ms (RTD0-50, RTD0-100, and RTD0-200, respectively), in sequence from 50 to 100 ms and 100 to 200 ms (RTD50-100 and RTD100-200), as the slope of 20-80% of peak torque (RTD20-80), and as the maximal instantaneous slope (RTDPeak). Torque signals were then downsampled to 100 Hz and all RTD variables re-calculated. Limb Symmetry Indices (LSI) were computed for all variables at both SR. Bland-Altman analyses, intraclass correlation coefficients (ICC), and root-mean-square errors (RMSE) assessed the agreement between 2000 Hz and 100 Hz RTD variables for both involved limb RTD and between-limb LSIs. RESULTS: Knee extensor RTD0-50, RTD50-100, and RTD0-100 demonstrated the lowest levels of agreement between 100 Hz and 2000 Hz SR. Conversely, RTD0-200, RTD20-80, and RTDPeak had the highest levels of agreement.CONCLUSIONS: Involved limb RTD and RTD LSI for RTD0-200, RTD20-80, and RTDPeak can be accurately assessed with reduced sampling rates, thereby facilitating use of clinically available equipment for assessing knee extensor RTD post-ACLR.

Optimizing speckles for dynamic objects using genetic algorithm in ghost imaging

Different from the traditional imaging methods using first-order interference, ghost imaging (GI) uses the second-order correlation, bringing many potential applications. On the other hand, GI has been suffering from low efficiency in image reconstruction due to a high sampling rate, which is a barrier for its application, especially when dealing with dynamic objects. The genetic algorithm (GA) can optimize the speckle sequence for an object and enable GI reconstruction with a few speckle patterns. However, the optimized speckle sequence of the GA usually loses the generalization and can only reconstruct the object being tested, making it far from suitable for handling a dynamic object. Here, we propose an improved method based on the GA, where we make two selection rules: the selective patterns more likely have a high response from the object, and meanwhile, the selected patterns tend to be linearly independent from each other. The optimized speckle sequence under these rules not only results in successful reconstruction but also preserves a generalization to a certain extent, enabling the GI to reconstruct the different states of the dynamic object at a low overall sampling rate. In the verification of the first frame, our method performs better based on the demonstration of various algorithms. In a demonstration of the dynamic object at 50% sampling rate, the reconstructed images are 2.1775 dB higher at 12 different frames on average in the peak signal-to-noise ratio than the random speckle sequence.

AUTOMATION OF GEODESIC MONITORING HIGH-RISE STRUCTURES

The article considers the existing methods used in the problem of geodetic monitoring of structures, analyzes the possibilities and gives a preliminary assessment of the accuracy of their use in monitoring high-rise structures. Methods have been identified that allow obtaining measurement results with a high sampling rate and have the potential for automation. Methods have been identified that allow solving the problem of calculating the daily fluctuations of a structure from the effects of solar radiation and wind load separately from the values of heel and draft.