Sensor Measurements Research Articles

Credibility-based multi-sensor fusion for non-Gaussian conversion error mitigation

In a complex environment, a multi-sensor fusion algorithm can compensate for the limitations of a single sensor’s performance. In a distributed fusion algorithm, sensors need to transmit local estimates to a central coordinate system, and the existence of coordinate transformation uncertainty can undermine the performance of data transmission. Therefore, this paper proposes a multi-sensor distributed fusion method based on trustworthiness. Firstly, considering the presence of non-Gaussian conversion errors, a credibility-based multi-sensor fusion framework is constructed. Secondly, to address the difficulty in estimating conversion errors when measurement errors follow a non-Gaussian distribution, an optimization model is constructed based on actual measurement information to estimate the distribution of non-Gaussian conversion errors. Then, in response to the non-linear and non-Gaussian characteristics of the target optimization function, a particle swarm optimization algorithm based on trustworthiness adaptive weights is proposed to estimate the coordinate transformation errors. Finally, given the inconsistency in local estimates due to missing sensor measurements or significant errors in a non-Gaussian complex environment, a maximum correntropy consensus algorithm is proposed to avoid the trustworthiness calculation being affected by the current measurement errors, thereby improving the accuracy of the global estimation.

Nitrogen fertilization and sowing date as wheat climate change adaptation tools under Mediterranean conditions

In the current situation, climate change has substantially disturbed precipitation occurrence in the Mediterranean region, by increasing its variability and decreasing the total annual amount, which both negatively affect rainfed crop productivity. We hypothesize that a simple cost-effective method for enhancing crop adaptation to new climate conditions would consist of modifying the crop sowing date. Traditional nitrogen (N) fertilization rates could also be adjusted to the current situation given the interdependent water/N relation in plant nutrition. Based on this hypothesis, during a 4-year field experiment with bread wheat (Triticum aestivum L., var. Pistolo), the effects of three sowing dates (October, November, February) and three N fertilization rates (54kgN ha-1, 27kgN ha-1, 0kgN ha-1) on crop development, yield, grain quality, soil N content and N use efficiency were analyzed. The results showed that water scarcity was the predominant limiting factor, because it outweighed N deficiency with half-fertilized crops being as productive as fully fertilized treatments. Nevertheless, sowing date was the most influential factor, with up to a 30% yield increase noted for the November-sown wheat compared to that sown in October, while delaying wheat sowing to February decreased crop yields. Grain protein content remained the same between the November- and October-sown crops, but increased in the February one crops. Optical sensor measurements showed that an optimal assessment of the current water/N nutritional status of crops can be achieved with these tools.

Shrinkage behaviour of high-strength concrete plates reinforced with carbon textile reinforcement

Carbon textile reinforcement is a relatively new type of CFRP reinforcement which, when utilized with high-strength concrete, leads to the production of ultra-thin free-form concrete shells. However, such reinforcement usually suffers from weak resistance to compressive stresses, while high-strength concrete is susceptible to high shrinkage rates. This combination may lead to a boor shrinkage behaviour, and thus an excessive shrinkage-related craking. Therefore, this paper aims to study the shrinkage behaviour of high-strength concrete plates reinforced with carbon textile reinforcement. Additionally, the utilization of shrinkage-compensating concrete as a possible shrinkage mitigation method was also investigated. For this aim, twelve concrete plates of dimensions 500 mm × 150 mm x 30 mm were cast. The shrinkage and expansion behaviour of the specimens were monitored for six months using the distributed fibre optic sensor (DFOS) technology, and then all the specimens were tested till failure under a direct tension test. The results have revealed that the existence of textile reinforcement does not provide any significant resistance to the negative strains generated from the shrinkage of concrete, which, for restrained concrete plates, leads to the formulation of wide cracks. On the other hand, the utilization of shrinkage-compensating concrete not only eliminates the formulation of shrinkage-related cracks but also reduces the crack’s width resulting from the loading process by up to 35 % during all stages of loading as illustrated by the fibre optic sensors measurements. Additionally, shrinkage-compensating concrete exhibits a slightly higher compressive strength than normal concrete.

Identification of characteristics of conceptual prototype of microprocessor resource-saving relay protection system

The object of the study is the conceptual prototype of a microprocessor resource-saving relay protection system. Currently, relay protection ensures electrical networks reliable and efficient work, however, the traditional architecture is proprietary, not allowing to fix and replace damaged parts without a company specialist. Therefore, the open-architecture relay protection is a very pressing issue, but the problem lies in meeting the relay protection requirements. The data transmission protocols nRF and ESP-NOW, Hall sensors evaluation for AC current measurement determination and sensor accuracy improvement was implemented. Experimental validation demonstrated that nRF and ESP-NOW protocols meet the delay and reliability requirements, however, the nRF protocol is more suitable due to its flexibility and obstacle penetration. The data demonstrated that the most effective conditions are without obstacles at 15 meters from the modem and with obstacles 5 meters from the modem. The experiment of Hall sensors characteristics determination demonstrated the accuracy of current measurement with the set values of the opening and closing currents. Nevertheless, it is not accurate (12.45 %) for the relay protection application. Therefore, the application of the changing values of the opening and closing currents is more effective and accuracy reaches 6.92 %. As a result, the service life of the Hall sensor was determined, and even after 10 million openings, the open state time remained unchanged. Therefore, the approximation function for current amplitude determination depending on open state time was found. On the other hand, Hall sensors may suffer from temperature drift and require further optimization to be fully reliable. The study limitation is the current range from 0 to 800 A

Temperature field analysis and compensation improvement of load cell

During the operation of load cell, heat is generated by the strain gauge and the electronics on the PCB board, which leads to temperature gradients within the sensor itself. These temperature gradients are unstable at different ambient temperatures. Compensation inaccuracies can also occur when compensating for sensor measurements at different temperatures This paper proposes a method to change the position of temperature compensation resistors to address errors caused by the temperature field effect of the strain gauge sensor itself. Without affecting the sensor’s strain measurement, the correctness of the proposed method is demonstrated through steady-state thermal simulation results in ANSYS and experimental results, effectively addressing errors caused by unstable temperature gradients during the operation of strain gauge sensors.

Long-Distance Measurements Using a Chromatic Confocal Sensor

In this work, we demonstrate the use of a chromatic confocal sensor for long-distance measurements. The sensor increases the working distance of state-of-the-art confocal sensors by a factor of 10, reaching a working distance of 620 mm. The chromatic aberration exhibited by a lens was utilized to establish the working range. The chromatic dispersion of the optics led to images of the different wavelength components at different longitudinal points along the optical axis. The sensor employs a robust algorithm to measure relative displacements of the sample’s motion. The calibration process simplifies data analysis and improves the accuracy of displacement measurements in experimental setups. To facilitate the design process, a simulator was developed specifically for this purpose. The calibration data obtained in both the experimental and the simulated data show that the simulator was able to predict the sensitivity with an error of 5%. We also describe the effect on the sensitivity of oversampling the spectrum. In addition, the superiority of low-pass filtering over Gaussian fitting over the detected spectrum is shown.

The Analysis of the Thermal Processes Occurring in the Contacts of Vacuum Switches During the Conduction of Short-Circuit Currents

This article presents the results of research on the thermal state of vacuum switch contacts during the conduction of short-circuit currents. This state is directly related to the value of the flowing current and the operating conditions of the switch. These conditions are mildest in the case of the conduction of operating currents through closed contacts. The situation worsens significantly when short-circuit currents are conducted, and the greatest destructive effects occur during commutation processes. Exceeding a certain level of contact destruction usually leads to the loss of the switching capacity of the switch. In vacuum switches, tracking the thermal state of the contacts is particularly difficult due to the inaccessibility of transducers or measurement sensors inside the chamber. In such a case, simulation studies verified by experimental results are important. This paper presents the results of such studies, directed at their practical implementation in the design and operation of vacuum switches. Simulation studies were conducted to analyze the thermal processes occurring in the contacts of vacuum switches during the conduction of short-circuit currents. Special attention was paid to the influence of contact parameters on the thermal processes occurring during the conduction of short-circuit currents. In addition to simulations, experimental studies were carried out to verify the simulation results. Ultimately, the research results presented are intended to provide practical knowledge of the design and operation of vacuum switches, particularly with regard to the contact heating processes during the conduction of short-circuit currents.

Energy Optimization in Ultrasound Tomography Through Sensor Reduction Supported by Machine Learning Algorithms

This paper focuses on reducing energy consumption in ultrasound tomography by utilizing machine learning techniques. The core idea is to investigate the feasibility of minimizing the number of measurement sensors without sacrificing prediction accuracy. This article evaluates the quality of reconstructions derived from data collected through two or three measurement channels. In subsequent steps, machine learning models are developed to predict the number, location, and size of the objects. A reliable object detection method is introduced, requiring less information than traditional signal analysis from multiple channels. Various machine learning models were tested and compared to validate the approach, with most demonstrating high accuracy or R2 scores in their respective tasks. By reducing the number of sensors, the goal is to lower energy usage while maintaining high precision in localization. This study contributes to the ongoing research on energy efficiency in sensing and localization, especially in environments where resource optimization is crucial, such as remote or resource-limited settings.

Large Range Curvature Measurement Using FBGs in Two-Core Fiber with Protective Coating

In this work, we propose a fiber Bragg grating (FBG)-based sensor for curvature measurements. Two gratings are inscribed through the protective coating in a specialty optical fiber using focused femtosecond laser pulses and point-by-point direct writing technology. One grating is inscribed on the central core adjacent to an air channel, while the other is inscribed on the eccentric core. The bending characteristics of the two-core fiber strongly depend on the bending direction due to the asymmetry of the fiber cores. A bending sensitivity of 58 pm/m−1 is achieved by the FBG in the eccentric fiber core over the curvature range of 0–50 m−1 . Temperature and humidity cross-sensitivity could be significantly reduced by analyzing the differences in peak shifts between the two gratings. The sensor features a large sensing range and good robustness due to the presence of its protective buffer coating, which makes it a good candidate for curvature sensing in engineering fields.

Continuous monitoring of heart failure biomarker using a sensitive graphene-based electrical sensor

Abstract Heart Failure (HF) is a complex condition that imposes significant burdens on both patients and healthcare systems. The economic impact of HF therapy and management is substantial, underscoring the urgency for proactive measures to mitigate its development. Regular assessments play a pivotal role in identifying individuals at risk and initiating timely interventions to prevent or delay HF progression [1, 2]. NT-proBNP, an amine-terminated form of brain natriuretic peptide, emerges as a promising biomarker in the realm of chronic HF diagnosis, prognosis, and risk assessment [3]. Its utility lies in providing valuable insights into disease progression and prognosis. In recent years, biosensors based on Field Effect Transistors with Graphene (Gr) gate (GFET) have garnered attention for their rapid response, sensitivity, and on-chip integration [4]. Here, we present a sensitive miniaturized GFET sensor for continuous NT-proBNP measurement. The sensor is an array of GFET devices with sensing gates of a monolayer Gr decorated with aptamers as catch probes. Averaging over similar devices in an array approach ensures measurement consistency throughout the experiment. Moreover, the significant challenge posed by the Debye length in FET biosensors is effectively addressed through the functionalization with short folding aptamers [4]. The sensor is built based on a chip comprising an array of 28 individual micro GFETs (Fig. 1a). For the functionalization of Gr gates, we utilized 1-pyrene butyric acid N-hydroxysuccinimide ester as a linker between the aptamer probes and the Gr surface. Subsequently, the Gr surface was incubated with an amine-terminated aptamer solution (Fig. 1c). A schematic diagram of the sensory chip having a droplet of the sample is shown in Fig. 1b. To quantify NT-proBNP levels an 8µL droplet of the buffer solution containing a specific NT-proBNP concentration was deposited onto the sensor. The drain current (IDS) served as the sensor signal for each target concentration (Figs. 2a and 2b). The sensor signal decreased with increasing target concentration, while negligible response was observed when injecting blank buffers. This phenomenon can be attributed to the folding of aptamers upon binding to their target. Also, continuous measurement was conducted at a fixed gate voltage of 0.9V, recording the drain current while the target concentration gradually increased in the sample droplet. This process revealed a decrease in sensor current as we expected (Fig. 2c). The sensor exhibits remarkably low detection limits of 50 pg/mL and a linear range from 100 pg/mL to 10 ng/mL, which are highly conducive for early HF diagnosis and aligning well with reported NT-proBNP levels in patient biofluid [5]. The proposed sensor holds promise as a wearable device for continuous monitoring of high-risk patients. Additionally, this technology shows potential as a detection tool for acute heart failure in hospitalized patients.Sensor viewSensor responses

Development of a sensor for liquid film thickness measurements during annular flow in microchannels

Development of a sensor for liquid film thickness measurements during annular flow in microchannels

Characterizing post-compression of mJ-level ultrafast pulses via loose focusing in a gas cell

The ability to generate high-intensity ultrashort laser pulses is a key driver for advancing the strong-field physics and its applications. Post-compression methods aim to increase the peak intensity of amplified laser pulses via spectral broadening through self-phase modulation (SPM), followed by temporal pulse compression. However, other unavoidable nonlinear self-action effects, which typically occur parallel to SPM, can lead to phase distortions and beam quality degradation. Here we study the ability to compress high-energy pulses by loose focusing in a noble gas to induce nonlinear spectral broadening, while limiting unwanted nonlinear effects such as self-focusing. We introduce ptychographic wavefront sensor and FROG measurements to identify the regimes that optimize pulse compression while maintaining high beam quality. Using a 700 mbar argon-filled double-pass-based scheme, we successfully compress 2 mJ, 170 fs, 1030 nm laser pulses to ∼35 fs, achieving 90% overall flux efficiency and excellent stability. This work provides guidelines for optimizing the compressed pulse quality and further energy scaling of double-pass-based post-compression concepts.

Three-dimensional distribution of aerosols of multiple types at daily scale using TROPOMI spaceborne observations

We present new satellite-based daily observations of the 3D distribution of aerosols from most common types and origins, both over land and ocean, derived from TROpospheric Ozone Monitoring Instrument (TROPOMI) measurements. This is done using the so-called AEROS5P (AEROsol Sentinel 5 Precursor) approach which retrieves vertical profiles of aerosol extinction from passive measurements of high-resolution spectral reflectance in the visible and near infrared for cloud-free conditions. Previous work demonstrated the potential of this approach, but it was initially applicable only to biomass burning aerosols with limited spatial coverage over ocean. The new methodology presented here generalizes the method for the most common aerosol types and improves spatial coverage. We take advantage of an operational aerosol type product derived from Visible Infrared Imaging Radiometer Suite (VIIRS) observations, combined with those from TROPOMI, to choose a priori aerosol set of intensive properties (particle size and refractive index). AEROS5P shows good agreement in aerosol optical depth, when compared to observations from AErosol RObotic NETwork and other widely used satellite measurements. Additionally, the vertical distribution of aerosol plumes of different types derived from AEROS5P agrees well with lidar coincident observations from the Advanced Topographic Laser Altimeter System spaceborne sensor and ground-based measurements. We utilize AEROS5P to analyze the three-dimensional distribution of aerosols for four different scenarios. It traces the three-dimensional pathways of smoke from Canadian wildfires reaching the Eastern USA in July 2023, desert dust from the Namibian deserts over the southeast Atlantic Ocean confined near the surface during the same month, fine aerosol pollution over Western Europe during June 2019, and an extreme dust event mixed with fine aerosol pollution over Northern China in March 2021. These observations provide valuable insights into aerosol transport patterns, surface-level air quality impacts, and can potentially be used to assess the radiative effects at various atmospheric layers.

System Integration Design of High-Performance Piezo-Actuated Fast-Steering Mirror for Laser Beam Steering System

This paper presents an innovative piezo-actuated fast-steering mirror (FSM) that integrates control design and system operation to improve the tracking performance of laser beam steering (LBS) systems. The proposed piezoelectric FSM is centered on two pairs of stacked actuators functioning in the tip-tilt direction via novel flexible hinges with strain-gauge sensors for position measurement. The suggested flexible hinge scheme allows the first fundamental resonance mode with the optical mirror to exceed 400 Hz while achieving an actuation range of ±5 mrad. Thus, the design offers a wider mechanical actuation range than conventional piezoelectric FSMs. Moreover, LBS systems that use fast-steering motion controllers should be robust against dynamic disturbances, such as periodic external vibrations. Such disturbances, inherently associated with the operating conditions for LBS systems, typically reduce the stability of the tip-tilt motion. To attenuate the effects of such disturbances, a high-precision control system is necessary for the tip-tilt motion. Therefore, a control method integrating a proportional–integral controller with an adaptive feedforward control (AFC) algorithm is outlined to enhance tip-tilt tracking performance during high-speed scanning, compared with conventional LBS systems. Based on experimental findings, the AFC algorithm boosted control performance under dynamic disturbances, such as sinusoidal vibrations with multiple frequencies.

Selective and highly sensitive measurement of H2O2 and organic hydroperoxides with PtNP/Poly(Brilliant Green)/SPCE

This research presents a novel electrochemical approach for the selective measurement of hydrogen peroxide and organic hydroperoxides, which is pivotal in many fields. The study details the development of an advanced sensor using a one-pot, one-step synthesis to embed platinum nanoparticles within a 3D-polymeric matrix of poly (brilliant green) on screen-printed carbon electrodes. The modified surfaces were characterized using scanning and transmission electron microscopy, Raman spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The results obtained by amperometry showed that, at 0.1 V, only H2O2 produced an electrochemical signal, while, at higher potential (0.5 V), all the hydroperoxides tested exhibited an electrochemical signal. Sensitivities obtained for H2O2 by flow injection analysis were 431 ± 3 and 465 ± 4 μC mM−1 at 0.1 and 0.5 V, respectively, with detection limits (S/N = 3) 116 and 30 nM, respectively. For organic hydroperoxides, sensitivities ranged from 22.3 to 32.6 μC mM−1 at 0.5 V, and limits of detection from 1.15 to 5.95 μM. Chemometric analysis indicated the sensor can satisfactorily measure H2O2 in the presence of the organic hydroperoxides herein analysed. The proposed sensor showed excellent properties in terms of repeatability, reproducibility and stability, with minimal interference. The reliability of the sensor was verified by measuring hydroperoxides spiked in aqueous extracts from real air quality monitoring filters. These features highlight the suitability of the sensor for hydroperoxide measurement and underscore its reliability as a practical tool for real-world applications.

Adaptive Fault‐Tolerant Multiplicative Attitude Filtering for Small Satellites

ABSTRACTThis study tackles the problem of fault‐tolerant attitude estimation for small satellites. A probabilistic adaptive technique is presented for the multiplicative extended Kalman filter (MEKF) algorithm that is used in attitude estimation. The presented method is based on tracking the normalized measurement innovations in the filter and calculating the probability of the normal operation of the estimation system. Using this probability, the filter gain is corrected to maintain the tracking performance of the filter despite faulty measurements. In order to evaluate the performance of this method, several simulations are performed where different types of faults are introduced to the synthetic attitude sensor measurements (magnetometer and sun sensor) at different times. Simulation results are compared not only with a conventional EKF but also with another popular adaptive Kalman filter, an adaptive Kalman filter with multiple scaling factors (MSFs).

Quantifying mobile robot localization safety for an EKF-based SLAM estimator: An integrity monitoring approach

The safety of SLAM-based estimation for mobile robots is a challenging research problem, particularly for life- or mission-critical exploratory applications. To address this problem, this work proposes a method to utilize integrity risk, a widely used performance metric in aviation, to quantify SLAM-based mobile robot’s localization safety. More importantly, the approach accounts for sensor measurement faults, unknown deterministic errors that cannot be modeled via Gaussian white noise. The method is tailored for an EKF-based SLAM estimator, a chi-squared failure detector, and a local nearest neighbors data association criterion. The results show that data association errors can cause significant positioning performance degradation that can only be predicted using the proposed integrity risk metric. Furthermore, the study demonstrates that as the map’s landmark density increases, mobile robot localization safety improves, except when the landmark map’s density is too high to make the features indistinguishable, which leads to positioning safety degradation.

Distributed driving electric vehicle lateral stability control method considering time delay

This paper introduces a novel control method to address lateral stability challenge in distributed driving electric vehicles. By considering inherent time delay and unknown sensor measurement error generated from design, manufacturing, and external disturbances, the proposed approach achieves better robustness. Firstly, we establish a two-degree-of-freedom (2-DOF) dynamic model for lateral motion of an electric vehicle driven by in-wheel motors (EV-DIM). Based on this model, a control system considering time delay and unknown sensor measurement error is constructed. The control system incorporates a controller based on a dual domination gains observer, and its global asymptotic stability is rigorously proved by the Lyapunov method. Numerical simulations and co-simulations via CarSim and Simulink verify the method’s effectiveness. Compared to the sliding mode control, the proposed method shows better performance which indicates this approach promising for enhancing lateral stability of an electric vehicle.

Spectral location for the universal scaling regime in Martian atmospheric turbulence

Atmospheric turbulence, irregular fluctuations of the fluid state, is studied on Mars. Universality of the turbulence spectrum underpins atmospheric models where computational requirements preclude full fidelity simulations of the smallest scales. However, there are discrepancies among reports on the existence and spectral location of universal scaling in Martian atmospheric data. Here, results indicate the smallest resolvable structures from Martian wind speed data are still associated with the energetic regime, which may ultimately explain why multiple reports have not found a consistent Kolmogorov-like spectral regime on Mars. Universal spectral scaling of wind data from Perseverance’s Mars Environmental Dynamics Analyzer is used to estimate the thresholds that separate three turbulence regimes: energetic, inertial, and molecular dissipation. Wind measurements at 2-Hz, the fastest sampling rate for direct wind sensor measurements on Mars, resolves turbulence in the energetic regime and approaches the inertial regime, which is consistent with reported Martian dust devil sizes.

Carbon Dots Prepared by One-step Sintering Method and their Application for pH Detection

Introduction: In recent years carbon dots (CDs) have attracted researchers due to their unique physicochemical and fluorescent (FL) features, which can be applied in many fields such as battery materials, fluorescence sensing, display, biological imaging and photocatalysis. Method: We prepared CDs by using a facile one-step sintering method. The fluorescent properties and the application of pH detection were measured and analyzed. Results: The results show that CDs emit bright purplish-blue light centred at 425 nm excited by 355 nm UV light. FL intensity shows a linear relationship with pH values at 1~4 and 7~11, respectively. The reasonable mechanism of the tested effective pH sensitivity is discussed. Conclusion: Our study shows that the CDs prepared by the one-step sintering method have great potential to be used as pH sensors for physiochemical measurements.