Precise Displacement Research Articles

Precise and analytical calculation of interface surface area in sharp interfaces and multiphase modeling

Various kinds of Piecewise Linear Interface Calculations (PLIC) are commonly used in Computational Fluid Dynamics (CFD) for multiphase flows. Here, a new method is proposed to calculate the interface size for CFD simulations. This PLIC method with the modifier, Analytic Size Based [method], (PLIC-ASB), being that the calculation requires a symbolic equation and no approximation or numerical methods. The primary advantage of the PLIC-ASB is maintaining a sharp interface and providing for physics-based (not iterative or empirically derived factors) mass transfer due to the cell-by-cell accuracy. Along with the sharp interface, this method leads to precise interface displacements and suppresses parasitic velocities; altogether, this means an accurate model of the temperature distribution near the interface can be achieved. The PLIC-ASB method was compared directly against the VOF gradient method (most prevalent PLIC in multiphase simulations). Static testing for accuracy on various geometric shapes expressed as the color function on representative grids of cells. The PLIC-ASB had a better result than the VOF gradient method, with an average relative error of 3% and 13%, respectively. Spherical bubble growth simulations were performed with customized ANSYS-Fluent. Both interface calculation methods were tested. Foremost, the PLIC-ASB method produced experimentally and theoretically anticipated results. Parasitic velocities were problematic in the VOF gradient method simulations but only minor with the use of PLIC-ASB. Further, a trend of accuracy improving with reduced cell size was found with the PLIC-ASB, whereas no trend was present with the VOF-gradient method. The PLIC-ASB method has the characteristic limitations of any PLIC method, most notably requiring a straight-line approximation to suitably represent the multiphase interface; however, the straightforward implementation and accuracy make broad adoption reasonable.

Oscillating optical fiber speckle patterns: modeling and application

Speckle patterns produced by the interference between multiple optical fiber modes carry detailed information regarding the waveguide characteristics. However, reflection-type setups implemented with fiber coupler and mirror generate oscillating specklegrams that cycle consistently around well-defined states. To study such a peculiar phenomenon, an analytical model derived from a multimode fiber Fabry-Pérot interferometer investigates the contributions of the cavity length, refractive index, and laser wavelength, revealing a sinusoidal modulation of the correlation coefficient. Experiments confirm the effect of the fiber-mirror distance on the specklegram changes: computing the correlation and tracing the spatiotemporal evolution of a light granule through active contour models yielded a phase sensitivity of 15.71 rad/µm. Furthermore, the presented system works as a precise displacement sensor enhanced by the extended correlation algorithm, achieving 3 nm resolution with linear response over a 70 µm range.

Robot Coordination: Aeronautic Use Cases Handling Large Parts

The coordination of two collaborative robots to handle and hold huge parts is the main topic of this research. This study shows how flexible systems may accommodate large-volume components while situating components with a displacement precision between robots of no more than 10 mm into the parts, with the assistance of a single operator. The robots must be able to keep the parts in place while coordinating their movements to handle the parts and reducing external stressors. This paper suggests using collaborative robots to integrate flexible tools for adaptability to various elements in order to accomplish this goal without endangering the operators. The software architecture is described in full in this paper, including machine states to choose task executions, robot referencing in the workspace, remote monitoring via the digital twin, generation paths, and distributed control using a high-level controller (HLC).

Spatial and temporal variation of aseismic creep along the dilational jog of the West Valley Fault, Philippines: Hazard implications

Accelerated creep, primarily through vertical displacement, has been occurring along 15 en-echelon faults belonging to a 15 km-long and 1.5 km-wide, N-S-trending dilational jog of the active West Valley Fault (or West Marikina Valley Fault), on the southeastern part of Metro Manila, Philippines. The much-larger-than-known tectonic slip rates had been the only reliable evidence in support of excessive groundwater withdrawal as the trigger of creep in the 1990s. Recently available groundwater extraction data (1977–2019) could more directly and consistently link groundwater withdrawal to accelerated creep in the 1990s. Twenty years (1999–2019) of precise displacement measurements could also reveal significant spatial and temporal links between slip rate changes and patterns of groundwater extraction. Our analysis shows that greater rates of vertical displacement are related to the timing of faster extraction rates. Variations in slip rates between the northern and southern measurement sites are primarily due to regional differences in groundwater extraction, which are influenced by differences in the implementation of water extraction reduction regulations. Proximity to the key source of groundwater recharge (Laguna Lake) is also an influencing factor. Although there are many unknowns inherent to this type of study, continued depressurization could induce static stress changes that could modulate the timescale of earthquake occurrence due to the natural course of stress loading driven by regional tectonics. The current and potential effects of continued depressurization in the areas with high slip rates and surrounding regions are paramount considerations in crafting and implementing tighter and extended groundwater extraction regulations.

Low-Cost GNSS and Real-Time PPP: Assessing the Precision of the u-blox ZED-F9P for Kinematic Monitoring Applications

With the availability of low-cost, mass-market dual-frequency GNSS (Global Navigation Satellite System) receivers, standalone processing methods such as Precise Point Positioning (PPP) are no longer restricted to geodetic-grade GNSS equipment only. However, with cheaper equipment, data quality is expected to degrade. This same principle also affects low-cost GNSS antennas, which usually suffer from poorer multipath mitigation and higher antenna noise compared to their geodetic-grade counterparts. This work assesses the quality of a particular piece of low-cost GNSS equipment for real-time PPP and high-rate dynamic monitoring applications, such as strong-motion seismology. We assembled the u-blox ZED-F9P chip in a small and light-weight data logger. With observational data from static experiments—which are processed under kinematic conditions—we assess the precision and stability of the displacement estimates. We tested the impact of different multi-band antenna types, including geodetic medium-grade helical-type (JAVAD GrAnt-G3T), as well as a low-cost helical (Ardusimple AS-ANT2B-CAL) and a patch-type (u-blox ANN-MB) antenna. Besides static tests for the assessment of displacement precision, strong-motion dynamic ground movements are simulated with a robot arm. For cross-validation, we collected measurements with a JAVAD SIGMA G3T geodetic-grade receiver. In terms of precision, we cross-compare the results of three different dual-frequency, real-time PPP solutions: (1) an ambiguity-float solution using the Centre National d’Études Spatiales (CNES) open-source software, (2) an ambiguity-float and an AR (ambiguity-resolved) solution using the raPPPid software from TU Vienna, and (3) and a PPP-RTK solution using the u-blox PointPerfect positioning service. We show that, even with low-cost GNSS equipment, it is possible to obtain a precision of one centimeter. We conclude that these devices provide an excellent basis for the densification of existing GNSS monitoring networks, as needed for strong-motion seismology and earthquake-early-warning.

Development of a flexible tooling system for sheet metal bending

This article presents the design and development of a flexible tooling system for sheet metal bending. The flexible tooling system aims to reduce manufacturing disturbances and increase the efficiency of the forming process. First and foremost, the structural behaviour of the sheet metal is investigated using the finite element method for the numerical simulation of the three-point bending process. The analysis’ findings enabled the prediction of component reaction to loads, which are essential for the further optimization and enhancement of the tooling system’s flexibility. At the initial stage of the development phase, SolidWorks, the computer-aided design software, is utilized to visualise the flexible tooling system and improve the tooling connectivity design. Furthermore, the prototype is developed by integrating mechanical and electrical components, such as the Arduino Mega microcontroller, stepper motors, and digital stepper drivers. Automation is achieved by programming the Arduino microcontroller board and controlling the stepper motors’ movement to ensure precise displacement and speed control of the forming tools. The tooling system’s major qualities are its high flexibility, achieved through the implementation of two moveable support cylinders and the possibility of being further upgraded to a closed-loop forming system. The higher level of automation and optimization of the sheet metal bending process can lead to improved processing efficiency and help achieve the desired formed products with higher quality and the required geometric tolerance. It is expected that the development of a flexible tooling system will find widespread application in sheet metal bending processes, resulting in reduced material costs, rapid equipment set-up and higher processing repeatability.

A Parallel Optical Fiber Fabry–Perot Interferometer for Simultaneous Measurement of Relative Humidity and Temperature

A parallel optical fiber Fabry–Perot interferometer (FPI) and Vernier effect sensor for simultaneous high-sensitivity measurement of relative humidity (RH) and temperature is proposed and verified by experiments. Two sections of a single-mode fiber (SMF) are fixed on the precision displacement platform, aligning them and leaving a small gap between them, and then filling the gap with polydimethylsiloxane (PDMS) and polyimide (PI), respectively, to form two Fabry–Perot (F–P) cavities. To produce a Vernier effect when two F–P cavities are connected in parallel, the length of two F–P cavities must be accurately controlled to ensure that the free spectral range (FSR) of the two F–P cavities is similar. It is found that the F–P cavity filled with PI is sensitive to RH and temperature, while the F–P cavity filled with PDMS is only sensitive to temperature. Due to the different characteristics of the two F–P cavities, the simultaneous measurement of RH and temperature is realized by constructing the sensitivity measurement matrix. If they are connected in parallel to produce the Vernier effect, the RH and temperature sensitivities of the parallel structure can reach −11.388 nm/%RH and 18.436 nm/°C, respectively. The sensor has potential applications in the fields of biopharmaceuticals, environmental monitoring, food processing, and microbial sensing.

Interpolating Meshless Methods for 3D Elastic Problems

Interpolating meshless methods can directly impose boundary conditions because of the interpolation property which shows advantages in dealing with problems with boundary conditions. The interpolating element-free Galerkin method (IEFGM), the improved interpolating element-free Galerkin method (IIEFGM), and the radial point interpolation method (RPIM) are applied in this paper to solve the two-dimensional and three-dimensional elastic problems. IEFGM and IIEFGM are two different ways to change the status that the traditional element-free Galerkin method (EFG) does not have the interpolation property. IEFGM uses an improved interpolating moving least-squares (IMLS) method that employed singular weight functions while IIEFGM takes the improved interpolating moving least-squares method based on non-singular weight function. RPIM, one of the most widely used interpolating meshless methods, is compared with IEFGM and IIEFGM in this paper. The numerical results of two-dimensional and three-dimensional elastic problems show that the three types of interpolating meshless methods obtain high precision displacement solutions and stress solutions.

An Innovative Method of Measuring the Extension of the Piston Rod in Hydraulic Cylinders, Especially Large Ones Used in the Shipbuilding and Offshore Industry

Abstract The article presents the results of selected works related to the wider subject of research conducted at the Faculty of Mechanical Engineering and Shipbuilding at the Gdańsk University of Technology, regarding designing various on board devices with hydraulic drive for ships and other offshore facilities. One of the commonly used these mechanisms are hydraulic actuators with the measurement of the piston rod extension. The issue of precise measurement of the piston rod extension is extremely important in modern technologies of construction, assembly and precise displacement and positioning of large and heavy, both land and ocean engineering objects or structural elements with the use of several large hydraulic cylinders working in parallel. The article presents a one of two new patented P.425099 – A device for measuring the extension of a hydraulic cylinder piston rod. [1].

In-situ and off-line deformations of cylindrical walls manufactured by directed energy deposition with different dwell times

Deformation of directed energy deposition (DED) is an index to reflect the relationship among fabricating quality, parameters and process method. In the present work, Inconel 718 cylindrical walls are manufactured by hybrid additive and subtractive manufacturing (HASM) to investigate the deformation. In-situ and off-line measurements are used to detect the deformation of the cylindrical walls with laser displacement measurement sensor and precision contact probe. The finite element simulation is used to analyze the relationship among the temperature, stress and deformation. The effect of different interlayer dwell times (from 0 to 45 s) on residual stress and deformation are compared. The deformations of different positions and processing parameters are analyzed.

Analysis of Uncertainties in Inductance of Multi-Layered Printed-Circuit Spiral Coils.

Eddy-current sensors are widely used for precise displacement sensing and non-destructive testing. Application of printed-circuit board (PCB) technology for manufacturing sensor coils may reduce the cost of the sensor and enhance the performance by ensuring consistency. However, these prospects depend on the uniformness of the sensor coil. Inductance measurements of sample coils reveal rather considerable variations. In this paper, we investigate the sources of these variations. Through image analysis of cut-away cross-sections of sensor coils, four factors that contribute to the inductance variations are identified: the distance between layers, the distance between tracings, cross-sectional areas, and misalignment among layers. By using and extending existing method of calculating inductance of spiral coils, the inductance distributions are obtained when these factors are randomly varied. A sensitivity analysis shows that the inductance uncertainty is most affected by the uniformness of the spacings between coil traces and the distances between layers. Improvements in PCB manufacturing process can help to reduce the uncertainty in inductance.

A Differential Phase-Modulated Interferometer with Rotational Error Compensation for Precision Displacement Measurement

In this paper, a differential phase-modulated interferometer (DPMI) is proposed to compensate for the rotational error for precision displacement measurement. In DPMI, a reference interferometer sharing the same reference arm with the measurement interferometer is constructed. Using the two interferometers to differentially measure the displacement, the unbalanced environmental disturbance on the measurement can be minimized. An integrated 2 × 2 array photodetector (APD) is adopted in DPMI. Based on APD with differential wavefront sensing (DWS) technology, the rotation angle can be detected and compensated. Therefore, precision displacement without rotational error and unbalanced environmental disturbance can be achieved. Three confirmatory experiments were performed, and the experimental results show that the maximum displacement drift is reduced from 902.9 nm to 16.3 nm in 100 min stability test, the standard deviations between the pitch and yaw angles obtained by DPMI and Renishaw interferometer are 1.68 × 10−5° and 1.86 × 10−5°, respectively, and the maximum deviation between the measurement result of DPMI and the stage positioning before and after angle compensation is reduced from 5.207 μm to about 0.719 μm.

Characterisation of soil deformation over wide strain ranges in triaxial test with high-precision stereophotogrammetry

Stereophotogrammetry was adopted as a means to measure three-dimensional displacements of a soil specimen surface in triaxial tests. New developments include an efficient algorithm that resolves the relative displacements with high precision to the order of 10−3 mm, and strains in common-sized soil specimens to the order of 10−3%, while correcting for ray refraction effects caused by the pressure cell wall and water. The system, requiring only sets of compact-type digital cameras as hardware, allows a stiffness–strain curve to be determined over wide strain ranges spanning from 10−3% to virtually any large strain with a fixed configuration. This paper explains the proposed image analysis processes, which combine a ray tracing formulation by Zhang and co-workers, particle tracking velocimetry and sub-pixel digital image correlation in efficiently deriving accurate and precise relative displacements. Rigorous assessment of the accuracy and precision was conducted. As a demonstration, two undrained triaxial compression tests on reconstituted clay were performed with and without end lubrication. Both for small-strain (<0·05%) axial loading–unloading cycles and for monotonic loading to large axial strain (15%), the strain development was tracked and the specimen behaviour was characterised. These tests demonstrate that the new technique can be a useful option in a soil laboratory both for research and practice.

Nano-Displacement Measurement System Using a Modified Orbital Angular Momentum Interferometer

In this study, a nano-displacement measurement system is proposed and demonstrated both theoretically and experimentally, which was based on a modified Mach-Zehnder (M-Z) interferometer using two conjugated orbital angular momentum (OAM) beams. In contrast to the previous M-Z-based OAM interferometer, a reflection module is inserted into the reference arm instead of a simple mirror. As a result, the effect of the transverse position-dependence phase-shift caused by the dove prism can be clearly eliminated and a stable and robust (off-axis insensitive) petal-like interference pattern can be obtained successfully. More importantly, a significant rotation angle of the petal-like pattern vs. the tiny displacement of the tested object can be clearly observed. In accordance with the modified measurement setup, a novel phase-demodulation method enabling to quickly and accurately characterize the rotation angle of the petal-like interference-patterns is proposed and demonstrated also. A tiny displacement ranging from 50 to 800 nm with resolution of <inline-formula> <tex-math notation="LaTeX">$\sim 50$ </tex-math></inline-formula> pm has been measured successfully. The proposed approach may find applications in not only the ultra-high precision displacement sensor, but also the temperature, strain, and refractive index sensors.

Computational Optimization of the 3D Least-Squares Matching Algorithm by Direct Calculation of Normal Equations

3D least-squares matching is an algorithm that allows to measure subvoxel-precise displacements between two data sets of computed tomography voxel data. The determination of precise displacement vector fields is an important tool for deformation analyses in in-situ X-ray micro-tomography time series. The goal of the work presented in this publication is the development and validation of an optimized algorithm for 3D least-squares matching saving computation time and memory. 3D least-squares matching is a gradient-based method to determine geometric (and optionally also radiometric) transformation parameters between consecutive cuboids in voxel data. These parameters are obtained by an iterative Gauss-Markov process. Herein, the most crucial point concerning computation time is the calculation of the normal equations using matrix multiplications. In the paper at hand, a direct normal equation computation approach is proposed, minimizing the number of computation steps. A theoretical comparison shows, that the number of multiplications is reduced by 28% and the number of additions by 17%. In a practical test, the computation time of the 3D least-squares matching algorithm was proven to be reduced by 27%.

PPP-derived tropospheric ZWD augmentation from local CORS network tested on bridge monitoring points

This paper developed the tropospheric correction augmented PPP for the purpose of bridge displacement monitoring. ZWD is estimated from undifferenced observations collected by UK CORS, and further applied to augment PPP client for displacement at the bridge surveying points. Coordinate time series obtained by GPS DD are treated as the true bridge displacement, which is used to assess the standard and CORS ZWD augmented PPP solutions obtained by varying cutoff angles. The experimental results reveal that the displacement precision of standard PPP severely depends on the satellite geometry. Meanwhile, the CORS ZWD augmented PPP results are less affected. The RMSE of improved PPP time series in the vertical component drops by 12%, 49% and 66% for the 5°, 10° and 15° cutoff angle cases, respectively. CORS ZWD augmented PPP can improve the monitoring precision and eliminate irregular displacement time series due to poor satellite geometry.

Development of a Remote Displacement Measuring Laser System for Bridge Inspection

Measuring displacement is essential for assessing the safety of bridges. Non-contact sensors such as vision sensors can precisely measure displacement but may be expensive or incapable of micro-scale measurement at a low cost, unlike contact displacement sensors, which are economical but challenging to install. This study proposes an economical, remote non-contact sensor system. The system comprises a laser beam transmitter and a light receiver, deriving the displacement based on the position where the laser beam is irradiated to the light-receiving surface. To measure this, the light receiver was installed at the measurement point and included a wireless communicator to transmit the displacement data. A displacement experiment was conducted to evaluate the performance. The results confirmed that precise displacement measurements were possible at a resolution of 100 µm. For bridge load tests, a light receiver under a bridge was installed, laser beams irradiated to the light-receiving surface from a distance, and the displacement was measured for each test and compared with the values measured by a conventional contact sensor. The results were highly consistent with those of the existing sensor, indicating that the proposed sensor system applies to bridge loading tests and the safety diagnosis for various structures.

Design and application of the dynamic detection platform for testing the micromechanical properties of agricultural products

The micromechanical properties of agricultural products can be used to formulate simulation models and optimize processing parameters for harvest, packaging, and storage. In this study, a detection platform was designed for conducting mechanical tests on different specimens at the tissue level. The system provided controllable and precise displacements; the relative error was less than ±1.0%. The displacement and force measurements were calibrated. Micromechanical tests of apple parenchyma tissues were conducted to evaluate the performance of the proposed platform. The stress-strain curves of the specimens and the micrographs of the microstructures can be obtained simultaneously during the tests. The proposed platform has the capability to test mechanical properties and obtain micro behaviors of agricultural products at the tissue level, which helps in studying the failure mechanism of agricultural products under external loading. Keywords: elasticity module, micro tensile, parenchyma tissue, micromechanical properties, agricultural products DOI: 10.25165/j.ijabe.20221506.6548 Citation: Hao Y F, Wang Y W, Jiang Q J, Zhang J, Wang J. Design and application of the dynamic detection platform for testing the micromechanical properties of agricultural products. Int J Agric & Biol Eng, 2022; 15(6): 8–15.

Precise Displacement Control of Tap-Water-Driven Muscle Using Adaptive Model Predictive Control with Hysteresis Compensation

Precise Displacement Control of Tap-Water-Driven Muscle Using Adaptive Model Predictive Control with Hysteresis Compensation

High‐finesse nanoscale displacement sensor based on fiber optic polymer probe

AbstractAs an important branch in the field of precision measurement, optical fiber micro‐displacement measurement plays an increasingly important role in the fields of precision machining, bioengineering, and so forth. In this paper, an optical fiber probe with high coupling efficiency is prepared based on photopolymerization, and on the basis of this structure, a new type of nanoscale displacement sensor is designed and implemented. The sensitivity and linear fitting coefficient of the designed sensor are 0.00289 dBm/nm and 98.8% in the range of 0–1000 nm, respectively. The proposed sensor is highly stable and persistent, has the advantages of high sensitivity, simple structure, low cost of production, and easy operation, which has major advantages in the application of precision displacement sensing field.