As a simple and unsupervised feature learning method, sparse filtering has shown potential in rotating machinery fault diagnosis. However, sparse filtering has the following deficiencies: (a) the optimal sparsity of the learned features cannot be determined. (b) As a shallow network, sparse filtering has a limited capability of learning discriminative features under varying loads. (c) The diagnostic

The fast optimal attitude matrix (FOAM) for minimizing Wahba’s loss function solves the optimal attitude matrix directly and efficiently. This method is more intuitive compared with the method of calculating attitude quaternion. A method named super-FOAM (SFOAM) is proposed with a more precise initial iteration value and a faster iterative algorithm. A condition number estimation method of third-order

Uncertainties due to the magnification variation in sub-nanometer metrology using transmission electron microscopy (TEM) were experimentally evaluated by comparing the measured values of the (220) lattice spacing of a crystalline Si specimen acquired under various conditions. Interday variation of the magnification, intraday repeatability, rotation of the TEM image, specimen exchange, specimen position

To realize high-precision machining of free-form blade surfaces, it is necessary to measure and reconstruct the blade morphology several times. Sampling measurements and data compression through free-curve approximation technology are of great benefit in shortening the processing time. A novel B-spline approximation method is proposed in this paper, which can determine a few dominant points based on

In multipath-assisted simultaneous localization and mapping (SLAM), position-related information (delays and angles) in multipath components of radio signals is used to simultaneously localize user equipment (UE) and map the environment. Multipath-assisted SLAM often involves unknown parameters that are potentially time varying, such as measurement noise. Knowledge of the measurement noise is of critical

A global stereovision system combined with a local vision sensor is an effective approach to large-scale object measurement. However, obtaining the error distribution of such an approach remains a key research challenge in vision metrological applications. This paper investigates the calibration and the reconstruction uncertainty estimation method of the combined vision system. The measurement principle

An important aspect of space exploration and situational awareness involves the characterization of the surface geometry of space objects. This paper puts forward a precise three-dimensional (3D) reconstruction method for uncooperative spacecraft based on a low-resolution time-of-flight (ToF) depth camera coupled with a high-resolution optical texture camera. In the proposed approach, a texture-guided

The global navigation satellite systems (GNSS) carrier phase measurements form the basis of high-precision satellite positioning. These measurements are often accompanied by their code counterparts to enable one to compute single-epoch ambiguity-resolved positioning solutions. To avoid unwanted code modelling errors, such as code multipath, one may opt for a phase-only solution and take recourse to

Compared with the non-redundant inertial navigation system (INS), the redundant INS (RINS) has more error parameters and the system is more complicated. The calibration methods for non-redundant INS are unable to be adopted by RINS directly. Meanwhile, the inner lever arm effect of accelerometers is more severe in RINS, which is not supposed to be ignored in the error compensation. To solve the problems

A novel fault diagnosis method based on improved multiscale range entropy and hierarchical prototype (HP) is proposed in this paper. Firstly, considering that range entropy cannot analyze the complexity of time series from multiple perspectives, the coarse-grained process is combined with range entropy. In addition, to make the coarse-grained process more comprehensive, the selection of its starting

Semantic segmentation of high-resolution remote sensing images has a wide range of applications, such as territorial planning, geographic monitoring and smart cities. The proper operation of semantic segmentation for remote sensing images remains challenging due to the complex and diverse transitions between different ground areas. Although several convolution neural networks (CNNs) have been developed

Measurement planning is vital for automatic and digitalized aircraft assembly, and in particular, for the key execution sequences. In this article, a novel planning method that considers both order and efficiency is proposed. General rules are defined for the analysis of measurement tasks and their elements. A Laplace kernel function is then utilized for similarity quantification, and based on iterative

Although optical 3D topography measurement instruments are widespread, measured profiles suffer from systematic deviations occurring due to the wave characteristics of light. These deviations can be analyzed by numerical simulations. We present a 3D modeling of the image formation of confocal microscopes. For this, the light-surface interaction is simulated using two different rigorous methods, the

Thermographic phosphors have been employed for temperature sensing in challenging environments, such as on surfaces or within solid samples exposed to dynamic heating, because of the high temporal and spatial resolution that can be achieved using this approach. Typically, UV light sources are employed to induce temperature-sensitive spectral responses from the phosphors. However, it would be beneficial

This work concerns the accurate dimensional measurement of metal parts directly in a production environment. Applying an approach with the simultaneous measurement of part dimension and temperature over time (dynamically) followed by modeling of the thermo-mechanical effects, the corrected length at 20 C and its measurement uncertainty can be predicted. This paper describes a test campaign where the

This paper investigates the calibration and measurement uncertainty related to the use of different camera models in optical systems that include refractive surfaces. A refractive surface is an interface between media with different optical properties which introduces distortions in the imaging process due to the refraction of the lines-of-sight. This is an issue common to all the investigations of

The novel approach for holistic screw thread calibrations developed by the Physikalisch-Technische Bundesanstalt was published in 2019. A significant achievement has been made in order to meet increasing demands in manufacturing processes and quality assurance, particularly when workpieces with complex geometries are under inspection. This article deals with the verification of the previously presented

Measurement traceability, in which there is a documented chain of calibration links from a measurement back to a primary realisation of a unit, is vital for achieving the smallest uncertainty in metrology. A sensor that can provide a traceable link in harsh environments may be advantageous even if its uncertainty is larger than that of typical calibrated devices. A phosphor-based thermometer that has

Fluctuations in the head, discharge, and contaminants in the flow can damage parts of the Pelton wheel. An artificial intelligence technique has been investigated for the automatic detection of bucket faults in the Pelton wheel. Features sensitive to defect conditions are extracted from the raw vibration signal and its variational mode decomposition (VMD). The issue of slow convergence speed of the

Rolling bearings are widely used in spindle systems, and are usually arranged in pairs for higher running accuracy. Spalling often occurs on the outer ring of rolling bearings, and the impact of double spalling located on a single bearing is quite different from that of spalling on both bearings. This paper proposes a method for localizing double spalling based on radiated sound signals. A model of

This study experimentally examined the flow phenomena and pressure distribution on the wing of Advisory Group for Aerospace Research and Development Model B (AGARD-B) at a Mach number of 0.83. For simultaneous pressure and temperature measurement, a mesoporous pressure-sensitive paint (PSP) sensor was applied to one of the wings of AGARD-B at an angle of attack (AOA) of 0–8 and a temperature-sensitive

Due to the complex nonlinear relationship among many variables in the rectification process of vinyl chloride monomer (VCM), there is a problem that its concentration is difficult to measure in real time. A method based on the tabu whale optimization algorithm for optimizing the radial basis function neural network (RBFNN) to model the concentration of the VCM rectification process is proposed. Firstly

Acetone is a biomarker of diabetics. The exhaled acetone concentration of diabetics is higher than that of a healthy person. Semiconductor gas sensors provide an accurate non-invasive detection method for low-concentration breath acetone of diabetics, but the their selectivity presents a drawback. In order to detect the concentration of exhaled acetone accurately from exhaled breath, an acetone detector

The Shack–Hartmann wavefront sensor (SHWFS) has been widely used for measuring aberrations in adaptive optics systems. However, its traditional wavefront reconstruction method usually has limited precision under field conditions because the weight-of-center calculation is affected by many factors, such as low signal-to-noise-ratio objects, strong turbulence, and so on. In this paper, we present a ResNet50+

A major bottleneck in nanoparticle sizing is the lack of data comparability between techniques and between laboratories. However, this can be overcome by making the measurements traceable to the SI together with realistic uncertainty evaluation. In the present work, a novel approach is proposed to perform measurement uncertainty evaluation in a Bayesian framework by statistically modeling appropriately

Time-frequency (TF) analysis (TFA) to nonstationary signals can reveal the nonlinearly changing instantaneous frequencies (IFs) of signals; it is, therefore, widely used for rotating machinery fault diagnosis under time-varying speed conditions. However, the traditional TFA methods may only reveal the outline of IFs due to the extra TF diffusion caused by limited TF resolution, hindering the fault

In this paper, we develop a repeat positioning, scanning tunneling microscope (STM), whose core component is a new straight-push piezoelectric nanopositioner. The special rigid frame structure and straight-push stepping method of this nanopositioner ensure that there is no lateral deviation while it is stepping. It has a smaller volume and a lower driving voltage than that of traditional piezoelectric

In this study a state-of-the-art gamma-ray tomography (GRT) unit was used to measure the solids concentration distributions of high density, high attenuation clay/water/sand slurries in a 4 in. (100 mm) diameter recirculating pipe loop. The presence of neighbouring radiation sources on the GRT results in a scattered radiation contribution to the total intensity measured at each detector. The scattered

Recently, many excellent algorithms have made great progress in object detection, but there are also problems in these algorithms’ performance on targets of different sizes, and in particular in small object detection. Aiming at the problem of insufficient feature representation by the feature extractor, in this paper we propose a lightweight algorithm to improve feature extraction. The algorithm includes

Polymer solutions are often used to produce drag-reduced fluid flows, in which the drag reduction is achieved due to the solutions’ non-Newtonian shear-thinning and viscoelastic properties. However, experiments using polymer solutions are typically challenging due to the tendency of the polymer to degrade when subjected to intense shearing. The degradation reduces the amount of drag reduction as the

Online microparticle detection is of utmost importance for industrial production. This paper proposes a signal processing and feature identification strategy to achieve particle size statistics for online measurement in a three-phase stirred tank reactor based on the electrical sensing zone (ESZ) method. Signal denoising and de-interference are achieved using the wavelet soft threshold method combined

In the field of electrical impedance tomography (EIT), numerous studies have aimed at the optimal excitation/measurement strategies for improving conductivity distribution imaging, particularly in the applications involving highly contrasted materials. These studies focus on the conditions to be imposed on the currents fed into the electrodes and on their measurement counterparts, while making use

The compound fault diagnosis of rolling bearings has become a hot topic. In this study, a novel method based on adaptive sparse denoising (ASD) combined with periodicity weighted spectrum separation (PWSS) is proposed to diagnose compound faults in rolling bearings. Specifically, ASD reveals fault types and PWSS separates compound faults. First, ASD determines regularization parameters adaptively using

The improving quality of ultra-sensitive superconducting quantum interference devices has led to the construction of advanced full-tensor magnetic gradiometers (FTMGs) integrated on mobile carriers such as aircraft, vehicles and ships. FTMGs measure the smallest spatial magnetic gradients, possessing many practical advantages compared to conventional scalar surveys and three-component surveys. However

Low Earth orbit (LEO) satellites are a promising type of navigation augmentation satellite for current global navigation satellite systems. Aiming at the navigation function, an effective broadcast ephemeris model needs to be designed for LEO satellites. An enhanced integration-type broadcast ephemeris model is proposed in this study. First, the short-term periodical variation characteristics of LEOs’

Peak height detection is critical for blade tip clearance (BTC) measurement based on capacitive probes. However, the noise interference of the complicated working environments and instabilities of the rotation speed make high-precision peak detection a challenge. To solve this problem, a novel self-adaptive, multi-peak detection algorithm is proposed in this paper. The adaptive dual thresholds are

Measuring the positions of multiple targets is key in many positioning applications. Utilizing compressed sensing theory, measurements using the sparse direct position determination (DPD) methods are more accurate than the two-step methods and the traditional DPD methods. Position measurement with mobile access points (APs) expands the network coverage, increases information throughput and reduces

This paper presents a basic study of the possible application of roughness parameters for monitoring of the life cycle of 4D printed structures. Experiments were performed with the purpose of gaining some insight into a novel manufacturing technique that may be of future interest and to investigate measurement procedures which may be helpful in the effectively monitoring, maintenance and design of

This paper investigates the pressure sensitivity of a temperature-sensitive paint (TSP) which uses a clear coat as binder and the Ru(dpp) as luminophore, and then discusses its effect on heat flux determination. Systematic static calibrations of three TSP samples with different thicknesses (7.5 μm, 10.3 μm and 13.1 μm) are carried out in a temperature range of 298 K to 373 K and a pressure range of

The Lagrangian particle tracking shake-the-box (STB) method provides accurate evaluation of the velocity and acceleration of particles from time-resolved projection images for high seeding densities, giving an opportunity to recover the stress tensor. In particular, their gradients are required to estimate local pressure fluctuations from the Navier–Stokes equations. The present paper describes a grid-free

Aircraft structures are exposed to impact damage caused by debris and hail during their service life. One of the design concerns in composite structures is the resistance of layered surfaces to damage, which occurs from impacts with various foreign objects. Therefore, the impact localization and damage quantification of impacts should be studied and considered to address flight safety and to reduce

The release of raw global navigation satellite system (GNSS) observations by Google Android makes high-precision positioning possible with low-cost smart devices. This study contributes to this research trend by constructing a stochastic model based on raw GNSS observation characteristics from Android smartphones and verifying the feasibility of smartphone-based ambiguity fixing in the short-baseline

Wideband excitation signals are essential in bioimpedance spectroscopy for measurements in a time ensuring a quasi-stable measurement condition. In particular, for wearable biomedical systems, due to limited system resources, several aspects regarding measurement time, crest factor, slew rate requirements, frequency distribution, amplitude spectrum, and energy efficiency need to be thoroughly investigated

Despite the advance of intelligent fault diagnosis for rolling bearings, in industries, data-driven methods still suffer from data acquisition and imbalance. We propose an enhanced few-shot Wasserstein auto-encoder (fs-WAE) to reverse the negative effect of imbalance. Firstly, an enhanced WAE is proposed for data augmentation, in which squeeze-and-excitation blocks are applied to calibrate channel-wise

The recent advancements in high-resolution turbulence-statistics computation from ensemble particle tracking velocimetry (EPTV) data are now opening new possibilities in turbulent-flow characterisation. Measurements of full-field boundary layer profiles with a fine resolution close to the wall and up to the freestream with one single imaging setup are now feasible, thus paving the way to direct characterisation

A recent study investigated the propagation of error in a velocimetry-based pressure (V-pressure) field reconstruction problem by directly analyzing the properties of the pressure Poisson equation (Pan et al 2016 Meas. Sci. Technol. 27 084012). In the present work, we extend these results by quantifying the effect of the error profile in the data field (shape/structure of the error in space) on the

Submerged elements, such as cracks inside concrete material or hidden pathological tissue, can potentially threaten safety and health. Thus, the detection of abnormal objects internally is of importance and frequently required. In this study, we propose a novel electrical impedance measurement method with the assistance of a robotic system. Specifically, the proposed measurement method is able to perform

In the current study, a novel arrangement of acoustic paths with an on-off technique upon ultrasonic waves is proposed to enhance the accuracy and reduce the frequency of calibration of the ultrasonic flowmeter (USFM). In addition, a web of chord probes on the velocity profile with a novel rotating method is also proposed. Twenty velocity profiles, including 19 selected Salami asymmetric velocity profiles

We present techniques to measure fluid flow rates in single- and multi-phase fluid flows by detecting the motion of injected tracers. Our methods exploit acoustic impedance differences between liquids and gases to allow one to sense the presence of micron-sized gas bubbles in a liquid when it is irradiated with ultrasonic energy. By cross-correlating signals at multiple locations along the path of

Electric propulsion systems, such as ion thrusters and Hall thrusters, are widely utilized in aerospace. The target indirect measurement method (TIMM) is a simple and robust way to measure its thrust. In general, one can obtain the thrust by scaling up the force exerted on the target surface immersed in the plume flow. However, the charge exchange (CEX) allows ions to become neutral particles, increasing

The sidewall angle (SWA) of a nanostructure exerts influence on the performance of the nanostructure and plays an important role in processing nano-structural chips. It is still a great challenge to determine steep SWAs from far field measurements especially when the SWAs are close to 90. Here, we propose a far-field detection system to determine steep SWA of a cliff-shape step structure on a silicon

Resonant sensors using coupled micro-cantilever arrays have found wide applications in the ultrasensitive mass detection of biomolecules and chemical analytes. Experimental observations indicate that a target mass deposited on one of the cantilevers can be detected by measuring the change in resonant frequencies or in eigenmodes. Analytical works have studied eigenvalue and eigenmode sensitivities

A phononic-fluidic cavity sensor is a new type of acoustic fluid sensor to measure volumetric liquid properties. In our work, it consists of solid-air 3D phononic crystal (PnC) layers confining a fluidic cavity resonator to generate a strong, well separated cavity resonance within the phononic band gap. This allows for the measurement of changes in speed of sound of a liquid analyte with very high

To achieve linear measurement of electro-optic phase delay and improve the accuracy and measurement range of the optical voltage transducer (OVT), this paper proposes a linear phase delay detection method for an optical voltage transformer based on a strip S-wave plate. Using the strip S-wave plate, the phase delay can be directly converted into the displacement of the dark stripe of the strip spot

Deep residual networks (DRNs) are a state-of-the-art deep learning model used in the data-driven fault diagnosis field. Their especially deep architectures give them sufficient capacity to deal with very complex diagnosis issues. However, a neural network with excellent performance usually requires hundreds of thousands of parameters, which is unaffordable for use in current industrial machines due

The speed of rotating parts is often affected by different working conditions in mechanical equipment, which results in more complications in the feature mapping relationship. However, existing methods that address the large fluctuation problem in rotational speed have been formulated merely to improve test accuracy and do not consider the effects of irregular fluctuation frequency on the fault samples

Surface acoustic wave (SAW) sensing systems based on the received signal strength indication (RSSI) detection principle have recently gained considerable research attention because of their distinct advantages and disadvantages. However, the test mode requires constant sweeping, which severely limits the system’s dynamic response; to overcome this limitation, an effective solution is to establish a

The reference functions and tables for base-metal thermocouples, which relate temperature and electro-motive-force, are specified by thermocouple type, rather than by alloy composition. The common thermocouple types—E, J, K, N, and T—are required to meet the specifications within defined tolerance bands; referred to as either limits-of-error (ASTM, US) or class (IEC, UK and Europe). In this requirement

Vehicle on-board equipment (VOBE) is a significant component of the control system of high-speed railway train, the fault diagnosis of VOBE mainly depends on maintenance experience, which is inefficiency. The fault data of on-board equipment is described by natural language. Due to its unstructured, high-dimensional and unbalanced fault class distribution, it has become a challenge in fault diagnosis

Fitting a spatial arc to noisy point clouds with high accuracy and reproducibility is challenging, although it is important in many applications, such as precise measurement, computerized numerical control machining and robotic path planning. In optical measuring applications, an arc-shaped object is usually first scanned as point clouds by a 3D camera or multiple charge-coupled device cameras, and