Precise Deformation Research Articles

Surface deformation recovery algorithm for reflector antennas based on geometric optics.

Surface deformations of large reflector antennas highly depend on elevation angle. This paper adopted a scheme with the ability to conduct measurement at any elevation angle: carrying an emission source, an unmanned aerial vehicle (UAV) scans the antenna on a near-field plane, meanwhile the antenna stays stationary. Near-field amplitude is measured in the scheme. To recover the deformation from the measured amplitude, this paper proposed a novel algorithm by deriving the deformation-amplitude equation, which reveals the relation between the surface deformation and the near-field amplitude. By the algorithm, a precise deformation recovery can be reached at a low frequency (<1GHz) through single near-field amplitude. Simulation results showed the high accuracy and adaptability of the algorithm.

Calibration of hoop stress in ring tensile test with Zircaloy-4 tube

Since Zirconium (Zr) alloys have been widely used as cladding material in a nuclear fuel rod, material properties of Zr are essential in prediction of failure and undesirable deformation. This paper mainly concerns calibration procedure to obtain the hoop stress of Zircaloy-4 tube with a simple ring tensile (RTT) test linking with a Digital image correlation (DIC) technique since it is substantially difficult to obtain, directly, with specialized experiment such as burst test with internal pressure. The uniaxial tensile tests along the axial and RTT along the hoop directions were conducted with Zircaloy-4 tube in which anisotropic stains were analyzed with a DIC technique to validate appropriate deformation history. Anisotropic yield criterion based on the measured R-values (R θ = 1.88 and R z = 0.814) is able to capture the precise deformation mode in the ring tensile test. The flow curve along the hoop direction is calibrated by converting F, G, and H material parameters based on the R-values to the function of stress ratios.

Retrieving Precise Three-Dimensional Deformation on the 2014 M6.0 South Napa Earthquake by Joint Inversion of Multi-Sensor SAR

We reconstructed the three-dimensional (3D) surface displacement field of the 24 August 2014 M6.0 South Napa earthquake using SAR data from the Italian Space Agency’s COSMO-SkyMed and the European Space Agency’s Sentinel-1A satellites. Along-track and cross-track displacements produced with conventional SAR interferometry (InSAR) and multiple-aperture SAR interferometry (MAI) techniques were integrated to retrieve the east, north, and up components of surface deformation. The resulting 3D displacement maps clearly delineated the right-lateral shear motion of the fault rupture with a maximum surface displacement of approximately 45 cm along the fault’s strike, showing the east and north components of the trace particularly clearly. These maps also suggested a better-constrained model for the South Napa earthquake. We determined a strike of approximately 338° and dip of 85° by applying the Okada dislocation model considering a single patch with a homogeneous slip motion. Using the distributed slip model obtained by a linear solution, we estimated that a peak slip of approximately 1.7 m occurred around 4 km depth from the surface. 3D modelling using the retrieved 3D maps helps clarify the fault’s nature and thus characterize its behaviour.

A Mouse Model of Single and Repetitive Mild Traumatic Brain Injury.

Mild Traumatic Brain Injury (mTBI) can result in the acute loss of brain function, including a period of confusion, a loss of consciousness (LOC), focal neurological deficits and even amnesia. Athletes participating in contact sports are at high risk of exposure to large number of mTBIs. In terms of the level of injury in a sporting athlete, a mTBI is defined as a mild injury that does not cause gross pathological changes, but does cause short-term neurological deficits that are spontaneously resolved. Despite previous attempts to model mTBI in mice and rats, many have reported gross adverse effects including skull fractures, intracerebral bleeding, axonal injury and neuronal cell death. Herein, we describe our highly reproducible animal model of mTBI that reproduces clinically relevant symptoms. This model uses a custom made pneumatic impactor device to deliver a closed-head trauma. This impact is made under precise velocity and deformation parameters, creating a reliable and reproducible model to examine the mechanisms that contribute to effects of single or repetitive concussive mTBI.

Measurement of precise three-dimensional volcanic deformations via TerraSAR-X synthetic aperture radar interferometry

Multiple-aperture SAR interferometry (MAI) is an advanced technique that is used to retrieve actual surface motions by complementing missing components of InSAR measurements. Despite the wide use of the MAI method in the geosciences, X-band SAR has rarely been applied in MAI-based studies due to the relatively shorter decorrelation periods involved. Thus, we need to evaluate the MAI measurements from X-band SAR for the use in the geosciences. In this paper, an assessment of the MAI performance for TerraSAR-X system was carried out at the test site, Kīlauea Volcano, Hawaii, focusing on the Kamoamoa fissure eruption episode that occurred on March 6–10, 2011. The root-mean-square (RMS) errors of single MAI interferograms were 3.26±1.32cm and 2.95±0.77cm for descending and ascending datasets, respectively. Multi-stacked MAI interferograms showed reduced error levels of 1.77 and 2.04cm for descending and ascending datasets, respectively. In addition, empirical uncertainty models of the MAI measurements were generated with respect to the interferometric coherence of single- and multi-stacked MAI measurements, and these regression models enabled us to confirm the difference between the theoretical and practical accuracies of the MAI measurements. Moreover, the MAI-based 3D model based on high accuracy 3D maps showed some possibilities of new findings and interpretations of the geologic sources.

Fusing Meter-Resolution 4-D InSAR Point Clouds and Optical Images for Semantic Urban Infrastructure Monitoring

Using synthetic aperture radar (SAR) interferometry to monitor long-term millimeter-level deformation of urban infrastructures, such as individual buildings and bridges, is an emerging and important field in remote sensing. In the state-of-the-art methods, deformation parameters are retrieved and monitored on a pixel basis solely in the SAR image domain. However, the inevitable side-looking imaging geometry of SAR results in undesired occlusion and layover in urban area, rendering the current method less competent for a semantic-level monitoring of different urban infrastructures. This paper presents a framework of a semantic-level deformation monitoring by linking the precise deformation estimates of SAR interferometry and the semantic classification labels of optical images via a 3-D geometric fusion and semantic texturing. The proposed approach provides the first “SARptical” point cloud of an urban area, which is the SAR tomography point cloud textured with attributes from optical images. This opens a new perspective of InSAR deformation monitoring. Interesting examples on bridge and railway monitoring are demonstrated.

Sustainable Surface Deformation Related with 2006 Augustine Volcano Eruption in Alaska Measured Using GPS and InSAR Techniques

Augustine volcano, located along the Aleutian Arc, is one of the most active volcanoes in Alaska and nearby islands, with seven eruptions occurring between 1812 and 2006. This study monitored the surface displacement before and after the most recent 2006 eruption. For analysis, we conducted a time-series analysis on data observed at the permanent GPS(Global Positioning System) observation stations in Augustine Island between 2005 and 2011. According to the surface displacement analysis results based on GPS data, the movement of the surface inflation at the average speed of 2.3 cm/year three months prior to the eruption has been clearly observed, with the post-eruption surface deflation at the speed of 1.6 cm/year. To compare surface displacements measurement by GPS observation, ENVISAT(Environmental satellite) radar satellite data were collected between 2003 and 2010 and processed the SBAS(Small Baseline Subset) method, one of the time-series analysis techniques using multiple InSAR(Interferometric Synthetic Aperture Radar) data sets. This result represents 0.97 correlation value between GPS and InSAR time-series surface displacements. This research has been completed precise surface deformation using GPS and time-series InSAR methods for a detection of precursor symptom on Augustine volcano.

Experiments on electrohydraulic forming and electromagnetic forming of aluminum tube

Electromagnetic forming (EMF) and electrohydraulic forming (EHF) are typical high speed forming technologies characterized with improved formability of sheet metal, single-sided die, and high precision deformation of parts. In this work, the bulging experiments of aluminum alloy tubes by EMF and EHF were performed to investigate the attaching-die capability, wall thickness, working hardness, and residual plasticity of deformed tubes. The results showed that the bulged tube by EMF is of low attaching-die capability, remarkable rebound, serious thinning of wall thickness, and prone to rupture in the outer corner. However, the parts by EHF process are of high attaching-die capability, almost no rebound, relatively uniform thickness, and remarkable fillet filling in the inner corner. The load mechanism contributes to the different deformation results of both processes. With the almost equivalent deformation, the tensile deformation ability of EHF part is better than that of EMF one, and the discharge energy efficiency of the former is higher than that of the latter.

TU‐AB‐202‐09: Performance of Cross‐Modality DIR Algorithms Using Images Computed from a Novel, Tissue‐Like Phantom Capable of Reproducible Degrees of Deformation

Purpose:Develop a framework for the spatial accuracy assessment of multi‐modality deformable image registration (DIR) based on precise and reproducible deformations of a novel prostate phantom.Methods:An existing, tissue‐like prostate phantom has been adapted to allow quantifiable, reproducible, and variable degrees of volumetric deformation. This phantom is sequentially deformed into 11 stationary deformation states that can be individually imaged using CT, MRI, US and CBCT. The deformation is induced programmatically by changing the water volume of a balloon using a precise syringe pusher (5ml increments), effectively displacing and deforming the prostate and surrounding tissue. To demonstrate the phantom's utility as a DIR assessment tool, selected DIR algorithms (CT&lt;‐&gt;MR: Normalized Mutual Information, MR‐MR: Mutual Information, CT‐CT: Local Cross‐Correlation+Mutual Information) were applied to intra and cross‐imaging modalities depicting varying degrees of deformation. DIR accuracy was assessed via the DICE overlap score, calculated between the deformed prostate contour (computed by warping the manually delineated contour on the initial deformation state) and the manually delineated contour on the target deformation state.Results:DICE coefficients show excellent agreement of individual deformation states for MR and CT, hence validating the reproducibility of the induced deformation (&lt; 1.0 + 0.1 %). Intra‐modality DIR (MR‐MR, CT‐CT) shows good performance (0.93–0.98). CT‐to‐MR performance is acceptable only for the closest 5–6 deformation states (&gt; 0.94), while the DIR solutions for farthest 6 deformation states (0.78–0.92) are erroneous or artifactual. MR‐to‐CT DIR performance is demonstrably weaker (0.0–0.96) yielding asymmetrical errors w.r.t. the initial deformation state (no‐deformation vs. maxdeformation). Moreover, the first 3 deformed contours show zero overlap with the manual contours.Conclusion:We have developed a novel prostate phantom capable of gradual and reproducible deformation, and demonstrated its ability to assess multi‐modality (CT&lt;‐&gt;MR) DIR algorithm performance and range. Due to the phantom multi‐imaging capabilities, other cross‐imaging DIR algorithms can now be explored.

Patient-specific Deformation Modelling via Elastography: Application to Image-guided Prostate Interventions

Image-guided prostate interventions often require the registration of preoperative magnetic resonance (MR) images to real-time transrectal ultrasound (TRUS) images to provide high-quality guidance. One of the main challenges for registering MR images to TRUS images is how to estimate the TRUS-probe-induced prostate deformation that occurs during TRUS imaging. The combined statistical and biomechanical modeling approach shows promise for the adequate estimation of prostate deformation. However, the right setting of the biomechanical parameters is very crucial for realistic deformation modeling. We propose a patient-specific deformation model equipped with personalized biomechanical parameters obtained from shear wave elastography to reliably predict the prostate deformation during image-guided interventions. Using data acquired from a prostate phantom and twelve patients with suspected prostate cancer, we compared the prostate deformation model with and without patient-specific biomechanical parameters in terms of deformation estimation accuracy. The results show that the patient-specific deformation model possesses favorable model ability, and outperforms the model without patient-specific biomechanical parameters. The employment of the patient-specific biomechanical parameters obtained from elastography for deformation modeling shows promise for providing more precise deformation estimation in applications that use computer-assisted image-guided intervention systems.

PPP Sliding Window Algorithm and Its Application in Deformation Monitoring

Compared with the double-difference relative positioning method, the precise point positioning (PPP) algorithm can avoid the selection of a static reference station and directly measure the three-dimensional position changes at the observation site and exhibit superiority in a variety of deformation monitoring applications. However, because of the influence of various observing errors, the accuracy of PPP is generally at the cm-dm level, which cannot meet the requirements needed for high precision deformation monitoring. For most of the monitoring applications, the observation stations maintain stationary, which can be provided as a priori constraint information. In this paper, a new PPP algorithm based on a sliding window was proposed to improve the positioning accuracy. Firstly, data from IGS tracking station was processed using both traditional and new PPP algorithm; the results showed that the new algorithm can effectively improve positioning accuracy, especially for the elevation direction. Then, an earthquake simulation platform was used to simulate an earthquake event; the results illustrated that the new algorithm can effectively detect the vibrations change of a reference station during an earthquake. At last, the observed Wenchuan earthquake experimental results showed that the new algorithm was feasible to monitor the real earthquakes and provide early-warning alerts.

Transient deformation induced by groundwater change in Taipei metropolitan area revealed by high resolution X-band SAR interferometry

We present precise deformation velocity maps for the two year period from September 2011 to July 2013 of the northern Taiwan area, Taipei, by using persistent scatterer interferometry (PSI) technique for processing 18 high resolution X-band synthetic aperture radar (SAR) images archived from COSMO-SkyMed (CSK) constellation. According to the result, the highest subsidence rates are found in Luzou and Wuku area in which the rate is about 15mm/yr and 10mm/yr respectively in the whole dataset. However, dramatic change from serve subsidence to uplift in surface deformation was revealed in the Taipei Basin in two different time spans: 2011/09–2012/09 and 2012/09–2013/07. This result shows good agreement with robust continuous GPS measurement and precise leveling survey data across the central Taipei Basin. Moreover, it also represents high correlation with groundwater table. From 8 well data in the Taipei basin, the storativity is roughly constant across most of the aquifer with values between 0.5×10−4 and 1.6×10−3 in Jingmei Formation and 0.8×10−4 and 1.4×10−3 in Wuku Formation. This high correlation indicated that one meter groundwater level change could induce about 9 and 16mm surface deformation change in Luzou and Wuku area respectively, which is about eight times faster the long-term tectonic deformation rate in this area. Thus, to access the activity of the Shanchiao Fault, it is important to discriminate tectonic movement from anthropogenic or seasonal effect in the Taipei Basin to better understand the geohazards and mitigation in the Taipei metropolitan area.

Method for Automated Bone Shape Correction within Bone Distraction Procedure

The method for automated bone shape correction within bone distraction procedure is presented. High precision deformation angle measurement is provided by the software for X- Ray images processing. Special BDC v.1.0.1. application is designed. The purpose of the BDC is modeling of the bone geometry structure to calculate the appropriate distraction forces. The correction procedure control is realized by the hardware of the distraction system.

Aortic root morphology: a paradigm for successful reconstruction.

Aortic root (AoR) components provide synchronous and precise 3D deformation of the aortic root during the cardiac cycle in order to ensure closure and opening of the three leaflets over a lifetime. Any deviation from the natural 3D morphology, such as with AoR annulus dilatation, enlarged sinuses and/or dilatation of the sinotubular junction, as in the case of ascending aortic dilatation, may result in disruption of the natural AoR function. Surgical treatment of AoR pathology has two modalities: the replacement of the aortic valve by artificial prosthesis or by preservation of the three leaflets and reconstruction of the aortic root components. Currently, there are two basic aortic root reconstruction procedures: aortic root sparing and aortic valve reimplantation techniques. Regardless of the technique used, the restoration of adequate cusp coaptation, is from a technical point of view, the most important element to consider. To achieve this, there are two requirements that need to be met: (i) the valve coaptation should be superior to the level of the aortic root base by at least 8 mm and (ii) the coaptation height per se has to be ≥5 mm. Successful restoration of the aortic root requires adequate technical skills, detailed knowledge of aortic root anatomy and topography, and also knowledge of the spatial pattern of AoR elements. Recently, there has been growing interest in aortic root reconstructive procedures as well their modifications. As such, the aim of this review is to analyse aortic root topography and 3D anatomy from a surgical point of view. The review also focuses on potential risk regions that one should be aware of before the surgical journey into the 'deep waters area' of the AoR begins.

Retrieving 65 years of volcano summit deformation from multitemporal structure from motion: The case of Piton de la Fournaise (La Réunion Island)

AbstractThe structure from motion photogrammetry technique enables use of historical airborne photography to achieve high‐resolution 3‐D terrain models. We apply this method on Piton de la Fournaise volcano (La Réunion), which allows a unique opportunity to retrieve high‐resolution (1.5–0.11 m) digital elevation models and precise deformation maps of the volcano since 1950. Our results provide evidence that the summit volume increased throughout the study period, at a stable rate of 2.2 Mm3/yr between 1950 and 2015, with an acceleration up to 8.0 Mm3/yr prior to the major 2007 eruption that was accompanied by summit caldera collapse. At the same time, summit deformation was asymmetric, with 9.2 ± 2.5 m of eastward seaward displacement and 1.3 ± 2.5 m to the west during 1950–2015. Our results reveal a temporal evolution in the volcano magma influx rate and deformation. Tracking these fluxes and the long‐lived preferential eastern motion is crucial to mitigate risks associated to flank destabilization.

High Strain Rate Compression of Martensitic NiTi Shape Memory Alloys

The compressive response of martensitic NiTi shape memory alloys (SMAs) under high strain rate (1200 s−1) was investigated on a modified Kolsky (Split Hopkinson) compression bar. The single-loading momentum trapping system ensures precise deformation control (1.4, 1.8, 3.0, 4.8, and 9.6 % strain) and single loading during dynamic compression. With increasing strain, the phase transformation peaks shift toward lower temperatures, while the intensities of these peaks decrease and eventually disappear completely at strains above ~7 %, where the onset of plastic deformation of reoriented martensite occurs. All transformation peaks are recoverable after deformation simply by annealing at 873 K (600 °C) for 30 min, except those peaks corresponding to strains above ~7 % (e.g., 9.6 %) which return upon annealing, but at a lower temperature. XRD results showed the variation of the strongest diffraction peak from (1 $$\bar{1}$$ 1) to (111) crystal plane before and after high strain rate compression.

Deformation behaviors of 21-6-9 stainless steel tube numerical control bending under different friction conditions

For contact dominated numerical control (NC) bending process of tube, the effect of friction on bending deformation behaviors should be focused on to achieve precision bending forming. A three dimensional (3D) elastic-plastic finite element (FE) model of NC bending process was established under ABAQUS/Explicit platform, and its reliability was validated by the experiment. Then, numerical study on bending deformation behaviors under different frictions between tube and various dies was explored from multiple aspects such as wrinkling, wall thickness change and cross section deformation. The results show that the large friction of wiper die–tube reduces the wrinkling wave ratio η and cross section deformation degree ΔD and increases the wall thinning degree Δt. The large friction of mandrel–tube causes large η, Δt and ΔD, and the onset of wrinkling near clamp die. The large friction of pressure die–tube reduces Δt and ΔD, and the friction on this interface has little effect on η. The large friction of bending die–tube reduces η and ΔD, and the friction on this interface has little effect on Δt. The reasonable friction coefficients on wiper die–tube, mandrel–tube, pressure die–tube and bending die–tube of 21-6-9 (0Cr21Ni6Mn9N) stainless steel tube in NC bending are 0.05–0.15, 0.05–0.15, 0.25–0.35 and 0.25–0.35, respectively. The results can provide a guideline for applying the friction conditions to establish the robust bending environment for stable and precise bending deformation of tube bending.

Simultaneous Measurement of In-Plane and Out-of-Plane Deformations Using Dual-Beam Spatial-Carrier Digital Speckle Pattern Interferometry

Digital speckle pattern interferometry (DSPI) is an advanced technique for both in-plane and out-of-plane deformation measurements of diffuse surfaces in nanoscale. It has been widely used in aerospace engineering and other high-tech industries due to the advantages of non-contact, high-accuracy and full-field measurement. Traditionally, DSPI uses temporal phase shifting method to achieve precise deformation measurement, but it is only suitable for quasi-static deformation. Spatial-carrier method is another effective phase retrieval method used in DSPI and its validity has been verified in some DSPI setups. DSPI with spatial-carrier method enjoys the advantages of simple optical arrangement, easy operation, and above all, high-speed measurement of deformation. This paper introduces a dual-beam spatial-carrier digital speckle pattern interferometry system, with which in-plane and out-of-plane deformations can be measured simultaneously as well as quickly. In the optical setup, two lasers are employed to illuminate the measured object with different illumination angles, and two single-mode fibers server as carriers to transmit the reference beams. In-plane and out-of-plane deformations can be obtained by combining the phase maps of both channels. Theoretical discussion and experimental analysis are both presented.

3D corrective osteotomy of malunited upper limb fractures

Corrective osteotomy for malunited fractures of the upper extremity remains a challenging procedure. Anatomical correction is the key to good clinical outcome after corrective osteotomy for malunited fractures, especially in cases of the upper extremity. To make a precise deformity correction in malunion, we have developed a computer-assisted system for corrective surgery, including a three-dimensional (3-D) program and a patient specific instrument (PMI), and investigated the results of corrective surgery for malunited fractures of the distal radius (MFRD), forearm diaphyses (MFFD) and distal humerus (cubitus varus deformity: CVD) with the use of this technology.

조립형 드릴의 성능 평가

Recently, the use of assembled-type drills as environmentally friendly products has expanded because the shanks of drills can be reused by replacing the tip when the tools are worn or cut. In addition to their precision and endurable stiffness with respect to the cutting force, assembled-type drills need no stricture because of thermal deformation, which makes replacement easily. In this study, we developed novel assembled-type drills and compared their characteristics, such as the precision, stiffness, and thermal deformation, with those of conventional drills. The new drills exhibited a precision over IT 8 class and no changes in dimensions due to thermal deformation, such that we can change the assembly easily with durability.