Deflection Detection Research Articles

IMU-Assisted Manual 3D-Ultrasound Imaging Using Motion-Constrained Swept-Fan Scans.

Three-dimensional (3D) ultrasonic imaging can enable post-facto plane of interest selection. It can be performed with devices such as wobbler probes, matrix probes, and sensor-based probes. Ultrasound systems that support 3D-imaging are expensive with added hardware complexity compared to 2D-imaging systems. An inertial measurement unit (IMU) can potentially be used for 3D-imaging by using it to track the motion of a one-dimensional array probe and constraining its motion in one degree of freedom (1-DoF) rotation (swept-fan). This work demonstrates the feasibility of an affordable IMU-assisted manual 3D-ultrasound scanner (IAM3US). A consumer-grade IMU-assisted 3D scanner prototype is designed with two support structures for swept-fan. After proper IMU calibration, an appropriate KF-based algorithm estimates the probe orientation during the swept-fan. An improved scanline-based reconstruction method is used for volume reconstruction. The evaluation of the IAM3US system is done by imaging a tennis ball filled with water and the head region of a fetal phantom. From fetal phantom reconstructed volumes, suitable 2D planes are extracted for biparietal diameter (BPD) manual measurements. Later, in-vivo data is collected. The novel contributions of this paper are (1) the application of a recently proposed algorithm for orientation estimation of swept-fan for 3D imaging, chosen based on the noise characteristics of selected consumer grade IMU (2) assessment of the quality of the 1-DoF swept-fan scan with a deflection detector along with monitoring of maximum angular rate during the scan and (3) two probe holder designs to aid the operator in performing the 1-DoF rotational motion and (4) end-to-end 3D-imaging system-integration. Phantom studies and preliminary in-vivo obstetric scans performed on two patients illustrate the usability of the system for diagnosis purposes.

Deformation analysis of prefabricated structures in the shaking table test based on density point clouds

ABSTRACT In this paper, a point cloud extraction method based on the template grid was proposed for deformation analysis. Firstly, coordinate alignment was carried out by a coarse-to-fine strategy to ensure that the point clouds are in a unified coordinate system. Then, the points in the grid are subsequently converted into a universal grid system and the center according to the grid border is carried out to serve as the feature points for deflection detection. The deformation was determined by analyzing the deviation under different working conditions, and the maximum deformation under different earthquake magnitudes was verified in the experiment.

Neuromorphic antennal sensory system

Insect antennae facilitate the nuanced detection of vibrations and deflections, and the non-contact perception of magnetic or chemical stimuli, capabilities not found in mammalian skin. Here, we report a neuromorphic antennal sensory system that emulates the structural, functional, and neuronal characteristics of ant antennae. Our system comprises electronic antennae sensor with three-dimensional flexible structures that detects tactile and magnetic stimuli. The integration of artificial synaptic devices adsorbed with solution-processable MoS2 nanoflakes enables synaptic processing of sensory information. By emulating the architecture of receptor-neuron pathway, our system realizes hardware-level, spatiotemporal perception of tactile contact, surface pattern, and magnetic field (detection limits: 1.3 mN, 50 μm, 9.4 mT). Vibrotactile-perception tasks involving profile and texture classifications were accomplished with high accuracy (> 90%), surpassing human performance in “blind” tactile explorations. Magneto-perception tasks including magnetic navigation and touchless interaction were successfully completed. Our work represents a milestone for neuromorphic sensory systems and biomimetic perceptual intelligence.

Methane gas spectral imaging method based on dual wedge scanning mirrors

With the increase in the number of oil and gas pipelines laid in China, more attention needs to be paid to pipeline maintenance work. At present, the main methods of detecting natural gas leaks in oil and gas transmission stations include manual inspections, opposing natural gas detection equipment, and cloud desktop natural gas detection equipment. Hand held natural gas detection equipment is used for manual inspection, which requires regular manual inspection. However, the response speed is poor and gas leaks cannot be detected in a timely manner. The opposed laser gas detection method can only detect the presence of gas on the beam path. If a larger area of leakage detection is desired, more equipment needs to be installed, resulting in a greatly increase in hardware costs. The existing cloud desktop laser gas detection method controls the deflection of the laser beam through the cloud platform to achieve leak detection at various points in the area to be tested. However, the rotation speed of the cloud platform is slow, and a complete detection cycle takes dozens of minutes, and only the presence of gas can be detected. For accurate leak location, manual on-site survey is also required to further determine the leak location. In order to meet the needs of the real-time monitoring and rapid positioning of oil and gas pipeline leaks, in this work, a fast and accurately controlled dual wedge scanning mirror system is designed, which combines tunable semiconductor laser absorption spectroscopy technology to convert the gas measurement laser beam from point measurement to surface measurement, thereby obtaining the two-dimensional distribution of gas, which is conducive to subsequent analysis and positioning of gas leakage sources. By using the inverse solution iterative optimization algorithm, the angle of the wedge mirror is controlled to obtain an efficient and uniform beam scanning trajectory. The deflection direction and detection position of the laser beam are fused with the corresponding methane concentration information, and a methane concentration data containing position information is constructed. In order to quantitatively verify the measurement accuracy and spatial resolution in the experiment, a standard air bag is used to simulate the methane leakage distribution. The results show that the minimum detection limit of the system can be lower than 5×10<sup>–4</sup> m, and the spatial resolution can be less than 6 cm. At the same time, this method can adjust the scanning step node based on the measurement distance of the oil from gas station, thereby achieving adjustable imaging resolution. This imaging method provides a new idea for accurately positioning and detecting the methane leakage location and amount.

Deflection Basin Detection of Pavements Based on Linear Array Charge-Coupled Device (CCD) Photoelectric Sensors

Deflection is an important indicator of the overall pavement strength, and it is generally detected using the Falling Weight Deflectometer (FWD). In response to the shortcomings of FWD in use, a pavement deflection detection method based on a linear array charge-coupled device (CCD) photoelectric displacement sensor is proposed. Firstly, a detailed description is given of the working principle of the deflection detection photoelectric sensor for the center point of the deflection basin and other points. Secondly, a photoelectric displacement sensor using linear array CCD deflection detection is designed, including a laser, CCD signal processing module, CCD and its driver module, and upper computer communication module. Among them, the EPF10K20TC144-4 device of the FLEX 10K series from ALTERA company is used to generate CCD driving pulses; Two DM54LS245 are selected as the driving interface for CCD photoelectric sensors, and corresponding filtering and signal amplification circuits are designed to address the noise problem of CCD photoelectric signal injection. Finally, the fixed threshold method separates the background and image signals in the CCD photoelectric signal, and the microcontroller is connected to the serial port of the upper computer through the MAX232 chip. The displacement measurement experiment uses the designed linear array CCD photoelectric displacement sensor. The results show that the road deflection basin detection method by the linear array CCD photoelectric displacement sensor fully meets the actual detection requirements and can obtain dynamic deformation information of the tested road surface. It is helpful for a detailed understanding of the changes in the deflection basin of the road surface under load.

Research on Belt Deviation Fault Detection Technology of Belt Conveyors Based on Machine Vision

Traditional belt deflection detection devices for underground belt conveyors in coal mines have problems, such as their single function, poor fault location and analysis accuracy, low automation level, and low reliability. In order to solve the defects of traditional detection devices, the belt deviation faults of the underground belt conveyor transport process require to be detected effectively and reliably. This paper proposes a belt deviation detection method based on machine vision. This method makes use of a global adaptive high dynamic range imaging method to complete the brightness enhancement processing of the underground image. Then the straight-line features of the conveyor belt edges are extracted using Canny edge detection and the Hough transform algorithm. In addition, a dual-baseline localization judgment method is proposed to realize the identification of band bias faults. Finally, a test bench for belt conveyor deviation was built. Testing experiments for different deviations were conducted. The accuracy of the tape deviation detection reached 99.45%. The method proposed in this study improves the reliability of belt deviation fault detection of underground belt conveyors in coal mines and has wide application prospects in the field of coal mining.

Photothermally driven AFM of biological samples

Since its invention in 1986, the atomic force microscope (AFM) has evolved into a multifunctional toolbox. Although there have been many developments towards improving the fundamental elements of an AFM - the scanner, controller, deflection detection system, and AFM cantilevers - most AFM systems still rely on a dither piezo to induce oscillation of the tip.

A systematic study on three-roll continuous straightening process for LSAW pipes

Aiming at the low efficiency and unstable accuracy of the current mold-pressing straightening for LSAW pipes, a three-roll continuous straightening process is proposed in this study, which uses the roller straightening instead of mold bending. According to the novel technology, the calculation model of the theoretical straightening moment is derived based on the springback equation of plane bending with small curvature, and the calculation model of initial curvature is established for the new deflection detection method. Furthermore, the numerical simulation analysis is carried out for the LSAW pipe case, and a straightening experimental platform is built for experiments. The research shows that the accuracy of the theoretical moment equation required for straightening is directly related to the initial curvature, rather than the fitting accuracy of the deflection curve, and the low-order simple-fitting curvature calculation model has the highest reliability. In order to control the section distortion and the straightening blind area, the straightening roller should follow the equal diameter design principle, and the empirical formula of span estimation is given. Under the optimal conditions, the straightness of the corrected tubes can be controlled within 1.5‰ and the ovality of the section can be within 0.5%, which proves the feasibility and reliability of the new process. What’s more, the straightening system built in this work, including process analysis software, is conducive to the automation and popularization of the new process.

Detection and measurement of beam deflection in the Madeira Airport runway extension using digital image correlation

PurposePart of the runway at Madeira Airport is a platform above the sea at a 60 m height, supported by a series of frames. When aircraft land on this section, a load is exerted on the structure, resulting in bending of the beams which constitute the frames. A vision-based monitoring system was devised and implemented to measure the deflection of the runway's beams when a landing occurs.Design/methodology/approachAn area on the midspan of two beams, located on the area where aircraft are most likely to land, was prepared with a speckle pattern, and a camera was assembled above a column on each of the adjacent frames, enabling the computation of displacements using digital image correlation (DIC). The camera continuously acquires images of the monitored area and compares them to a reference using DIC. If a displacement is detected, a number of frames before and after this event are saved for further DIC processing.FindingsThe installed systems successfully detected several events corresponding to landings and, for each of those events, measured the deflection of the beams over time and computed displacement fields for critical images, with strain values obtained up to this point being too small to measure using the current system.Originality/valueThis work provides novel insights into the behaviour of a unique structure and constitutes the first use of a vision system in its structural monitoring operations. It is also a valuable development in the implementation of automated DIC monitoring systems in locations of difficult access.

Cellulose Nanocrystals (CNC) Liquid Crystalline State in Suspension: An Overview

Films made from cellulose nanocrystals (CNCs) may have iridescent structural colours (pure or in combination with other materials). Numerous fields might benefit from understanding how CNC self-assembly constructs these periodic structures. Herein, we looked at the colloidal characteristics of CNC particles as well as the development and behaviour of liquid crystals (LCs). We conducted a very brief literature analysis on the main issues related to the chiral structure creation of CNC LCs, including the origins of chirality, orientation, as well as its mechanical properties. Finally, by altering the pitch size, applications such as energy storage, humidity sensing, and photonic crystals were studied in a case-by-case manner. The manuscript, it is observed that the rational design of metamaterials built on CNCs allows for the reversible changing of colours through physical and chemical modifications by adding chemical or changing environmental factors. Examples of this alteration include the use of solvents, chemical penetration in applied fields (magnetic and electric), deflection, light, temperature change, acidity change, and molecular interaction detection. Reversible colours may be produced by altering the spacing between the particles, the filler materials, or the structural elements of the system’s refractive indices. This article briefly discusses the inner workings of CNCs, potential barriers to developing photonic structures, and several techniques and processes for achieving changeable colours.

A remote deflection detection method for long-span bridges using adaptive mask and high-resolution camera

A remote deflection detection method for long-span bridges using photogrammetry and computer vision is proposed. Through the proposed adaptive mask algorithm, the incorrect detection in the traditional photogrammetry method based on feature point matching is avoided. In addition, an ultra-telephoto lens and a high-resolution camera are used to take a remote video of the bridge, which achieves high precision, high sampling frequency and non-contact deflection detection of the long-span bridge. Experiments show that the proposed method can effectively avoid incorrect detection, and the measurement accuracy can reach millimetre-level within 500 m under various meteorological conditions, which is higher than the measuring robot. It also has the characteristics of long detection distance, high detection accuracy, high sampling frequency, non-contact, automatic target search and low cost. This method not only meets the requirements of deflection detection of long-span bridges but also has great application prospects in other structural displacement detection tasks.

Development of Railway Bridge Deflection Detection System Based on NI-cDAQ Inclinometer

Aiming at the limitation of the traditional deflection test method by the field application of railway bridge inspection, the paper develops a data acquisition and analysis system for bridge deflection inspection. The system is based on NI-cDAQ series acquisition equipment and the LabVIEW programming software development environment. Through the industrial Modbus bus protocol, it is possible to integrate the inclinometer, data acquisition equipment and other hardware acquisition equipment with the application software through the computer, and establish a complete set of practical instrument equipment and dynamic deflection detection process to achieve high speed, high precision and multi-channel acquisition Bridge deflection information. Combined with field tests for verification, the results show that the real-time collection and transmission of various parameters of the system can run for a long time under complex field conditions, with stable work and reliable data.

Dynamic displacement response analysis of bridge in the impact vibration of slight and frequent vehicle bump

To study the impact of vehicle moving on bridge, the bump occurring under the determined limit conditions of vehicle from no bump to the beginning of bump was named as slight and frequent vehicle bump. With a 1/4 simplified vehicle model and the Euler-Bernoulli bridge model, the required minimum impact height for the bump and the effect of bump impact on the vertical dynamic mid-span displacement response of bridge were figured out in different vehicle speed, axle load and wheel diameter. The simulation analysis by ANSYS software, with HSFLD242 unit simulating air inside the tire and MASS21 simulating the car weight held by tires, verified the results of the minimum impact height. The effect of bump impact on the vertical dynamic mid-span displacement response of bridge was also verified by observation using the TCQN-6A bridge deflection detector on the mid-span dynamic deflection of a 25-metre simply supported beam bridge.

Study of Structural Characteristics of Asphalt Overlays on Airport Pavement with Damaged Load Transfer Efficiency of Joints

In this paper, the real joint load transfer efficiency of airport pavement is calculated by combining the results of airport pavement deflection detection and ground-penetrating radar detection. Spring elements are used to simulate the actual load transfer efficiency of joints in ABAQUS. The impact of different asphalt overlays on the stress state of the critical point in the pavement is analyzed by the airport cement concrete pavement model. The result shows that adding a thin stress-absorbing layer with fine-graded and low modulus can effectively disperse the load transferred from the asphalt pavement to the cement pavement and the stress concentration at the joint under the asphalt overlay. Compared with airport pavement without a stress-absorbing layer, the tensile stress and shear stress at the critical point in the airport pavement asphalt overlay decreased by 24.62% and 22.49%, respectively. Therefore, the combination of the high-modulus upper layer and low-modulus lower layer can effectively reduce the tensile stress and shear stress at the critical point. In addition, increases in the thickness of the asphalt overlay can effectively improve the stress state at the critical point. When the thickness of the asphalt overlay changed from 13 cm to 21 cm, the maximum tensile and shear stress decreased by 8.82% and 8.92%, respectively. Finally, based on the analysis of the numerical simulation and field test verification, the optimal airport pavement asphalt overlay scheme is proposed.

Technology for Location, Analysis and Interpretation of Magnetic Alterations as Precursors of Seismic Phenomena Update

To date, several studies have shown that the Earth's magnetic field suffers alterations at the local geographical location before an earthquake occur. Its study demonstrates that the Earth’s magnetic alterations at specific local geographical zone, is a local seismic precursor alerting a proximity of an earthquake with a margin of error of approximately 10%. The electromagnetic noise from background is very confusing, but that reason was necessary to identify these electromagnetic signal precursors by filtering a large amount of noise. To isolate the electromagnetic noise, was implemented a Magnetic North deflection detection in Smart Phones Magnetometers. Using it technology, was developed a mathematical algorithm that work in combination with the Smart Phones magnetometers. This research was based using in reference the study carried out by the Department of Physics of the Faculty of Physical Sciences and Mathematics (FCFM) of the University of Chile directed by Cordado, 2018[1], in the paper called “Latitudinal variation rate of geomagnetic cutoff rigidity in the active Chilean convergent margin”.

Investigation of a metrological atomic force microscope system with a combined cantilever position, bending and torsion detection system

Abstract. This article presents a new metrological atomic force microscope (MAFM) head with a new beam alignment and a combined one-beam detection of the cantilever deflection. An interferometric measurement system is used for the determination of the position of the cantilever, while a quadrant photodiode measures the bending and torsion of the cantilever. To improve the signal quality and reduce disturbing interferences, the optical design was revised in comparison to the systems of others (Dorozhovets et al., 2006; Balzer et al., 2011; Hausotte et al., 2012). The integration of the MAFM head in a nanomeasuring machine (NMM-1) offers the possibility of large-scale measurements over a range of 25mm×25mm×5 mm with sub-nanometre resolution. A large number of measurements have been performed by this MAFM head in combination with the NMM-1. This paper presents examples of the measurements for the determination of step height and pitch and areal measurement.

A metrological atomic force microscope system

A new metrological atomic force microscope (MAFM) with combined deflection detection system that comprises a homodyne interferometer and an optical beam deflection measuring system are presented. The combination allows the simultaneous three-dimensional detection of position, bending and torsion of the cantilever. Two wedge plates with a wedge angle of 0.5° have been integrated to reduce the disturbing interferences. The new measuring system uses two tiltable plane mirrors and a shiftable focus lens to adjust the direction of the focused laser beam and the position of the focus. The integration of the MAFM head in a nanomeasuring machine (NMM-1) creates the possibility of traceable dimensional measurements over a large range of 25 mm × 25 mm × 5 mm with sub-nanometre resolution. This paper introduces its setup, realisation and metrological properties, such as stability of the characteristic curves, noise level and combined measurement uncertainty. Finally, exemplary measurement results are presented.

Temperature Correction for FWD Deflection in Cement Pavement Void Detection

The use of the falling weight deflectometer (FWD) for detecting pavement voids is based on the principle that, under the same impact load, the deflection of pavements with voids increases significantly. Under the effect of temperature, the cement pavement becomes warped, which affects the deflection detection accuracy. In order to improve the accuracy of FWD detection of cement pavement voids, a three-dimensional numerical model of cement pavement on a multilayered elastic foundation under the coupled action of temperature and load is established in this paper. In addition, under different pavement void, climatic, and load conditions, the influence of temperature difference between top and bottom of the plate on the deflection of the center point of plate angle load is studied. Considering the temperature difference between top and bottom, the temperature correction coefficient is established and experimentally verified the accuracy of the temperature correction coefficient. The results showed that, within the ranges of positive and negative temperature differences, the fitting degree of the temperature correction coefficient for the cement pavement exceeded 0.99, which was consistent with the variation trend of the temperature correction coefficient obtained through field tests. The error was lower than 7%, which verified the applicability of the temperature correction coefficient for the dynamic deflection of cement pavements based on FWD. The accuracy of the FWD method in detecting cement pavement voids was improved, and this study demonstrated theoretical reference value and practical engineering significance.

The nano-scale viscoelasticity using atomic force microscopy in liquid environment

We measured viscoelasticity of two nanoscale systems, single protein molecules and molecular layers of water confined between solid walls. In order to quantify the viscoelastic response of these nanoscale systems in liquid environment, the measurements are performed using two types of atomic force microscopes (AFMs), which employ different detection schemes to measure the cantilever response. We used a deflection detection scheme, available in commercial AFMs, that measures cantilever bending and a fibre-interferometer based detection which measures cantilever displacement. The hydrodynamics of the cantilever is modelled using Euler–Bernoulli equation with appropriate boundary conditions which accommodate both detection schemes. In a direct contradiction with many reports in the literature, the dissipation coefficient of a single octomer of titin I278 is found to be immeasurably low. The upper bound on the dissipation coefficient is 5 × 10−7 kg s−1, which is much lower than the reported values. The entropic stiffness of single unfolded domains of protein measured using both methods is in the range of 10 mN m−1. We show that in a conventional deflection detection measurement, the phase of the bending signal can be a primary source of artefacts in the dissipation estimates. It is recognized that the measurement of cantilever displacement, which has negligibly small phase lag due to hydrodynamics of the cantilever at low excitation frequencies, is better suited for ensuring artefact-free measurement of viscoelasticity compared to the measurement of the cantilever bending. Further, it was possible to measure dissipation in molecular layers of water confined between the tip and the substrate using fibre interferometer based AFM with similar experimental parameters. It confirms that the dissipation coefficient of a single I278 is below the detection limit of AFM. The results shed light on the discrepancy observed in the measured diffusional dynamics of protein collapse measured using Force spectroscopic techniques and single-molecule optical techniques.

Development of electrochemical high-speed atomic force microscopy for visualizing dynamic processes of battery electrode materials.

Development of lithium ion batteries with ultrafast charging rate as well as high energy/power densities and long cycle-life is one of the imperative works in the field of batteries. To achieve this goal, it requires not only to develop new electrode materials but also to develop nano-characterization techniques that are capable of investigating the dynamic evolution of the surface/interface morphology and property of fast charging electrode materials during battery operation. Although electrochemical atomic force microscopy (EC-AFM) holds high spatial resolution, its imaging speed is too slow to visualize dynamics occurring on the timescale of minutes. In this article, we present an electrochemical high-speed AFM (EC-HS-AFM), developed by addressing key technologies involving optical detection of small cantilever deflection, dual scanner capable of high-speed and wide-range imaging, and electrochemical cell with three electrodes. EC-HS-AFM imaging from 1 fpm to ∼1 fps with a maximum scan range of 40 × 40 µm2 has been stably and reliably realized. Dynamic morphological changes in the LiMn2O4 nanoparticles during cyclic voltammetry measurements in the 0.5 mol/l Li2SO4 solution were successfully visualized. This technique will provide the possibility of tracking dynamic processes of fast charging battery materials and other surface/interface processes such as the formation of the solid electrolyte interphase layer.