Academic literature on the topic 'Displacements reconstruction'
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Journal articles on the topic "Displacements reconstruction"
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Roy, Rinto, Alexander Tessler, Cecilia Surace, and Marco Gherlone. "Shape Sensing of Plate Structures Using the Inverse Finite Element Method: Investigation of Efficient Strain–Sensor Patterns." Sensors 20, no. 24 (December 9, 2020): 7049. http://dx.doi.org/10.3390/s20247049.
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Methods for real-time reconstruction of structural displacements using measured strain data is an area of active research due to its potential application for Structural Health Monitoring (SHM) and morphing structure control. The inverse Finite Element Method (iFEM) has been shown to be well suited for the full-field reconstruction of displacements, strains, and stresses of structures instrumented with discrete or continuous strain sensors. In practical applications, where the available number of sensors may be limited, the number and sensor positions constitute the key parameters. Understanding changes in the reconstruction quality with respect to sensor position is generally difficult and is the aim of the present work. This paper attempts to supplement the current iFEM modeling knowledge through a rigorous evaluation of several strain–sensor patterns for shape sensing of a rectangular plate. Line plots along various sections of the plate are used to assess the reconstruction quality near and far away from strain sensors, and the nodal displacements are studied as the sensor density increases. The numerical results clearly demonstrate the effectiveness of the strain sensors distributed along the plate boundary for reconstructing relatively simple displacement patterns, and highlight the potential of cross-diagonal strain–sensor patterns to improve the displacement reconstruction of more complex deformation patterns.
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Benca, Emir, Ivan Zderic, Jan Caspar, Kenneth van Knegsel, Lena Hirtler, Boyko Gueorguiev, Harald Widhalm, Reinhard Windhager, and Peter Varga. "On Measuring Implant Fixation Stability in ACL Reconstruction." Sensors 21, no. 19 (October 6, 2021): 6632. http://dx.doi.org/10.3390/s21196632.
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Numerous methods and devices are available for implant fixation in anterior cruciate ligament (ACL) reconstruction. Biomechanical data indicate high variability in fixation stability across different devices. This study aims to provide a better insight into measuring the structural characteristics and mechanical behavior of ACL implant fixations. Fourteen human tibial specimens with reconstructed ACLs were subjected to progressively increasing dynamic loading until failure. The motions of the tibia, the proximal and distal graft ends, as well as the testing frame and actuator, were continuously recorded via a motion tracking system. Significantly higher displacements of the machine actuator (1.0 mm at graft slippage onset, and 12.2 mm at ultimate load) were measured compared to the displacements of the proximal (0.8 and 4.3 mm, respectively) and distal graft (0.1 and 3.4 mm, respectively) ends. The displacements measured at different sites showed significant correlations. The provided data suggest significant and systematic inaccuracies in the stiffness and slippage of the fixation when using machine displacement, as commonly reported in the literature. The assessment of the distal graft displacement excludes the artifactual graft elongation, and most accurately reflects the graft slippage onset indicating clinical failure. Considering the high displacement at the ultimate load, the ultimate load could be used as a standardized variable to compare different fixation methods. However, the ultimate load alone is not sufficient to qualitatively describe fixation stability.
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Le Hanneur, Malo, Andrew Thoreson, Damien Delgrande, Thibault Lafosse, Jean-David Werthel, Philippe Hardy, and Bassem Elhassan. "Biomechanical Comparison of Anatomic and Extra-Anatomic Reconstruction Techniques Using Local Grafts for Chronic Instability of the Acromioclavicular Joint." American Journal of Sports Medicine 46, no. 8 (May 10, 2018): 1927–35. http://dx.doi.org/10.1177/0363546518770603.
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Background: Anatomic reconstruction techniques are increasingly used to address cases of acromioclavicular (AC) joint chronic instability. These usually involve an additional surgical site for autograft harvesting or an allograft. Purpose: To describe a triple-bundle (TB) anatomic reconstruction using on-site autografts, the semiconjoint tendon (SCT) and the coracoacromial ligament (CAL), and compare its primary stability to the native AC joint ligamentous complex and to a modified Weaver-Dunn (WD) reconstruction. Study Design: Controlled laboratory study. Methods: Intact AC joints of 12 paired cadaveric shoulders were tested for anterior, posterior, and superior translations under cyclic loading with a servo-hydraulic testing system. One shoulder from each pair was randomly assigned to the TB group, where 2 SCT strips were used to reconstruct the coracoclavicular ligaments while the distal end of the CAL was transferred to the distal extremity of the clavicle to reconstruct the AC ligaments; the other shoulder received a modified WD reconstruction. After reconstruction, the same translational testing was performed, with an additional load-to-failure test in the superior direction. Results: In both the TB and the WD groups, no significant differences were found before and after reconstruction in terms of joint displacements after cyclic loading, in all 3 directions. Compared with the WD reconstruction, the TB repair resulted in significantly lower displacements in both the anterior (ie, 2.59 ± 1.08 mm, P = .011) and posterior (ie, 10.17 ± 6.24 mm, P = .014) directions, but not in the superior direction. No significant differences were observed between the 2 reconstructions during the load-to-failure testing, except for the displacement to failure, which was significantly smaller (ie, 5.34 ± 2.97 mm) in the WD group ( P = .037). Conclusion: Anterior, posterior, and superior displacements after an anatomic reconstruction of the AC joint complex using the SCT and CAL as graft material were similar to those of native AC joints and significantly smaller in the axial plane than those of AC joints after a WD repair. Clinical Relevance: An anatomic reconstruction is achievable using the CAL and the SCT as on-site graft materials, providing satisfactory initial stability and thereby allowing earlier mobilization.
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Peng, Zhenrui, Kangli Dong, and Hong Yin. "A Modal-Based Kalman Filter Approach and OSP Method for Structural Response Reconstruction." Shock and Vibration 2019 (June 16, 2019): 1–15. http://dx.doi.org/10.1155/2019/5475686.
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The objective of the work is experimental validation and optimal experimental design for structural response reconstruction. A modal-based Kalman filter approach based on excitation identification Kalman filter is proposed for response reconstruction and excitation estimation of structures by using noisy acceleration and strain measurements. Firstly, different filters are introduced and discussed. Secondly, to avoid single type sensors, a displacement reconstruction based on modal method is introduced into the proposed approach. Thirdly, the backward sequential algorithm is given to obtain the optimal sensor locations. It is shown that the proposed method can avoid the divergency in the estimated process of excitation and displacements as a result of incomplete measurements. Reasonable estimates of strains, displacements, velocities, accelerations, and excitations of structures can be accomplished with few acceleration sensors and strain gauges.
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Esposito, Marco, Massimiliano Mattone, and Marco Gherlone. "Experimental Shape Sensing and Load Identification on a Stiffened Panel: A Comparative Study." Sensors 22, no. 3 (January 29, 2022): 1064. http://dx.doi.org/10.3390/s22031064.
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The monitoring of loads and displacements during service life is proving to be crucial for developing a modern Structural Health Monitoring framework. The continuous monitoring of these physical quantities can provide fundamental information on the actual health status of the structure and can accurately guide pro-active condition-based maintenance operations, thus reducing the maintenance costs and extending the service life of the monitored structures. Pushed by these needs and by the simultaneous development in the field of strain sensing technologies, several displacement reconstruction and load identification methods have been developed that are based on discrete strain measurements. Among the different formulations, the inverse Finite Element Method (iFEM), the Modal Method (MM) and the 2-step method, the latter being the only one able to also compute the loads together with the displacements, have emerged as the most accurate and reliable ones. In this paper, the formulation of the three methods is summarized in order to set the numerical framework for a comparative study. The three methods are tested on the reconstruction of the external load and of the displacement field of a stiffened aluminium plate starting from experimentally measured strains. A fibre optic sensing system has been used to measure surface strains and an optimization procedure has been performed to provide the best fibre pattern, based on five lines running along the stiffeners’ direction and with a back-to-back measuring scheme. Additional sensors are used to measure the applied force and the plate’s deflection in some locations. The comparison of the results obtained by each method proves the extreme accuracy and reliability of the iFEM in the reconstruction of the deformed shape of the panel. On the other hand, the Modal Method leads to a good reconstruction of the displacements, but also exhibits a sensitivity to the choice of the modes considered for the specific application. Finally, the 2-step approach is able to correctly identify the loads and to reconstruct the displacements with an accuracy that depends on the modeling of the experimental setup.
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Zhang, Qing, Xing Fu, Zhiguo Sun, and Liang Ren. "A Smart Multi-Rate Data Fusion Method for Displacement Reconstruction of Beam Structures." Sensors 22, no. 9 (April 20, 2022): 3167. http://dx.doi.org/10.3390/s22093167.
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Dynamic displacement plays an essential role in structural health monitoring. To overcome the shortcomings of displacement measured directly, such as installation difficulty of monitoring devices, this paper proposes a smart reconstruction method, which can realize real-time intelligent online reconstruction of structural displacement. Unlike the existing approaches, the proposed algorithm combines the improved mode superposition methods that is suitable for complex beam structures with the Kalman filtering approach using acceleration and strain data. The effectiveness of the proposed multi-rate data fusion method for dynamic displacement reconstruction is demonstrated by both numerical simulation and model vibration experiment. Parametric analysis shows that the reconstruction error is only 5% when the noise signal to noise ratio is 5 dB, illustrating that the proposed algorithm has excellent anti-noise performance. The results also indicate that both the high-frequency and low-frequency components of the dynamic displacements can be accurately reconstructed through the proposed method, which has good robustness.
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Xu, Hao, Qi Zhou, Lei Yang, Minjing Liu, Dongyue Gao, Zhanjun Wu, and Maosen Cao. "Reconstruction of full-field complex deformed shapes of thin-walled special-section beam structures based on in situ strain measurement." Advances in Structural Engineering 23, no. 15 (July 4, 2020): 3335–50. http://dx.doi.org/10.1177/1369433220937156.
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This study proposed a method capable of reconstructing complex deformations of thin-walled special-section beam structures subjected to highly coupled loading cases, in terms of the combination of tension/compression, biaxial bending, and warping torsion. The complex beam deformation was decoupled, depending on axial strain measurement strategy on beam surface, and leads to reconstructed full-field displacements (deformed shapes) as the linear superposition of deformations subject to individual loading types. Full-filed strain/stress distributions can then be derived based on the reconstructed displacements. Particular efforts were focused on reconstructing beam deformation subject to warping torsion, where both rotations angles and warping displacements across the beam cross-section and along the beam length were identified precisely. As a proof-of-concept validation, the effectiveness of the method was examined using finite element analysis, where the deformed shape of a thin-walled hat-section beam under the coupling between uniaxial bending and warping torsion was reconstructed., Experiments were conducted subsequently to reconstruct deformation of an aluminum hat-section beam using distributed optical fiber sensors for the measurement of axial strains on the beam surface. The reconstructed full-field deformed shapes of the beam were compared with the three-dimensional displacement signals captured using a non-contact digital image correlation system. The effectiveness of the proposed methodology for complex deformation reconstruction is possible to be extended to a variety of thin-walled beam-type structures which are typical in civil and aerospace engineering, showing potential contributions in fields such as on-line structural health monitoring and active structural control.
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Xu, Libo, Feifei Zhao, Jingli Du, and Hong Bao. "Two-Step Calibration Method for Inverse Finite Element with Small Sample Features." Sensors 20, no. 16 (August 16, 2020): 4602. http://dx.doi.org/10.3390/s20164602.
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When the inverse finite element method (inverse FEM) is used to reconstruct the deformation field of a multi-element structure with strain measurements, strain measurement errors can lower the reconstruction accuracy of the deformation field. Furthermore, the calibration ability of a self-structuring fuzzy network (SSFN) is weak when few strain samples are used to train the SSFN. To solve this problem, a novel two-step calibration method for improving the reconstruction accuracy of the inverse FEM method is proposed in this paper. Initially, the errors derived from measured displacements and reconstructed displacements are distributed to the degrees of freedom (DOFs) of nodes. Then, the DOFs of nodes are used as knots, in order to produce non-uniform rational B-spline (NURBS) curves, such that the sample size employed to train the SSFN can be enriched. Next, the SSFN model is used to determine the relationship between the measured strain and the DOFs of the end nodes. A loading deformation experiment using a three-element structure demonstrates that the proposed algorithm can significantly improve the accuracy of reconstruction displacement.
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Kashani, Hany, Graham Wright, Ali Ursani, Garry Liu, Masoud Hashemi, and Narinder Paul. "Restricting motion effects in CT coronary angiography." British Journal of Radiology 92, no. 1103 (November 2019): 20190384. http://dx.doi.org/10.1259/bjr.20190384.
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Objective: Evaluation of coronary CT image blur using multi segment reconstruction algorithm. Methods: Cardiac motion was simulated in a Catphan. CT coronary angiography was performed using 320 × 0.5 mm detector array and 275 ms gantry rotation. 1, 2 and 3 segment reconstruction algorithm, three heart rates (60, 80 and 100bpm), two peak displacements (4, 8 mm) and three cardiac phases (55, 35, 75%) were used. Wilcoxon test compared image blur from the different reconstruction algorithms. Results: Image blur for 1, 2 and 3 segments in: 60 bpm, 75% R–R interval and 8 mm peak displacement: 0.714, 0.588, 0.571 mm (1.18, 0.6, 0.4 mm displacement) 80 bpm, 35% R–R interval and 8 mm peak displacement: 0.869, 0.606, 0.606 mm (1.57, 0.79,0.52 mm displacement) 100 bpm, 35% R–R interval and 4 mm peak displacement: 0.645, 0.588, 0.571 mm (0.98, 0.49, 0.33 mm displacement). The median image blur overall for 1 and 2 segments was 0.714 mm and 0.588 mm respectively (p < 0.0001). Conclusion: Two-segment reconstruction significantly reduces image blur. Advances in knowledge: Multisegment reconstruction algorithms during CT coronary angiography are a useful method to reduce image blur, improve visualization of the coronary artery wall and help the early detection of the plaque.
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Moulton, M. J., L. L. Creswell, S. W. Downing, R. L. Actis, B. A. Szabo, M. W. Vannier, and M. K. Pasque. "Spline surface interpolation for calculating 3-D ventricular strains from MRI tissue tagging." American Journal of Physiology-Heart and Circulatory Physiology 270, no. 1 (January 1, 1996): H281—H297. http://dx.doi.org/10.1152/ajpheart.1996.270.1.h281.
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A method is developed and validated for approximating continuous smooth distributions of finite strains in the ventricles from the deformations of magnetic resonance imaging (MRI) tissue tagging "tag lines" or "tag surfaces." Tag lines and intersections of orthogonal tag lines are determined using a semiautomated algorithm. Three-dimensional (3-D) reconstruction of the displacement field on tag surfaces is performed using two orthogonal sets of MRI images and employing spline surface interpolation. The 3-D regional ventricular wall strains are computed from an initial reference image to a deformed image in diastole or systole by defining a mapping or transformation of space between the two states. The resultant mapping is termed the measurement analysis solution and is defined by determining a set of coefficients for the approximating functions that best fit the measured tag surface displacements. Validation of the method is performed by simulating tag line or surface deformations with a finite element (FE) elasticity solution of the heart and incorporating the measured root-mean-square (rms) errors of tag line detection into the simulations. The FE-computed strains are compared with strains calculated by the proposed procedure. The average difference between two-dimensional (2-D) FE-computed strains and strains calculated by the measurement analysis was 0.022 +/- 0.009 or 14.2 +/- 3.6% of the average FE elasticity strain solution. The 3-D displacement reconstruction errors averaged 0.087 +/- 0.002 mm or 2.4 +/- 0.1% of the average FE solution, and 3-D strain fitting errors averaged 0.024 +/- 0.011 or 15.9 +/- 2.8% of the average 3-D FE elasticity solution. When the rms errors in tag line detection were included in the 2-D simulations, the agreement between FE solution and fitted solution was 24.7% for the 2-D simulations and 19.2% for the 3-D simulations. We conclude that the 3-D displacements of MRI tag lines may be reconstructed accurately; however, the strain solution magnifies the small errors in locating tag lines and reconstructing 3-D displacements.
Dissertations / Theses on the topic "Displacements reconstruction"
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Peters, Ashton. "Digital Image Elasto-Tomography: Mechanical Property Reconstruction from Surface Measured Displacement Data." Thesis, University of Canterbury. Department of Mechanical Engineering, 2007. http://hdl.handle.net/10092/2775.
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Interest in elastographic techniques for soft tissue imaging has grown as relevant research continues to indicate a correlation between tissue histology and mechanical stiffness. Digital Image Elasto-Tomography (DIET) presents a novel method for identifying cancerous lesions via a three-dimensional image of elastic properties. Stiffness reconstruction with DIET takes steady-state motion captured with a digital camera array as the input to an elastic property reconstruction algorithm, where finite element methods allow simulation of phantom motion at a range of internal stiffness distributions. The low cost and high image contrast achievable with a DIET system may be particularly suited to breast cancer screening, where traditional modalities such as mammography have issues with limited sensitivity and patient discomfort. Proof of concept studies performed on simulated data sets confirmed the potential of the DIET technique, leading to the development of an experimental apparatus for surface motion capture from a range of soft tissue approximating phantoms. Error studies performed on experimental data from these phantoms using a limited number of shape and modulus parameters indicated that accurate measurements of surface motion provide sufficient information to identify a stiffness distribution in both homogeneous and heterogeneous cases. The elastic reconstruction performed on simulated and experimental data considered both deterministic and stochastic algorithms, with a combination of the two approaches found to give the most accurate results, for a realistic increase in computational cost. The reconstruction algorithm developed has the ability to successfully resolve a hard spherical inclusion within a soft phantom, and in addition demonstrated promise in reconstructing the correct stiffness distribution when no inclusion is present.
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Arango, James Steven. "Slope Settlement and Post-Disaster Health Needs of Urban Displacement in La Paz, Bolivia." Scholar Commons, 2015. https://scholarcommons.usf.edu/etd/5447.
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In 2011, a landslide displaced approximately six thousand people from the urbanized mountain slopes of La Paz, Bolivia. The municipal government of La Paz (GAMLP) managed the displacement by housing thousands of people in displacement camps throughout the city. By 2013, residents were attempting to return to still damaged lands. This research used participant observation and interviews with residents over eight weeks in 2013 to address the following questions: 1) What social, cultural, economic or historic factors influence the settling and then resettling of at-risk slope neighborhoods in La Paz, Bolivia? 2) What are the most pressing health needs of people who have returned to slope neighborhoods and people still living in displacement camps? The research found that the return to at-risk slope properties was supported by entrenched cultural and social meanings attached to land and home ownership. While scarcity of resources galvanized communities to pressure authorities with demonstrations and threats, it also created intra-barrio frictions that disrupted reconstruction, strained existing infrastructure capabilities and threatened to undermine community health.
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Jasani, Rubina. "Communal Violence, Displacement and Muslim Identities: Negotiating Survival and Reconstruction in Ahmedabad, Western India." Thesis, University of Sussex, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487928.
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This thesis is an ethnographic study that aims to explore how communal violence and displacement changed the experiences of Muslim survivors of the violence of 2002 in . the state of Gujarat, Western India. The thesis looks at the moral and material reconstruction of life after the violence. The aim is to understand how the worst affected (in this context the migrant Muslims who had moved to the city from various Indian states to work in the textile mills, and who lived in the suburbs and outer suburbs of the city) were positioned in relation to state and civil society organisations (secular NGOs and community organisations) and how their location within these discourses shaped their perceptions of self, religion and the choices they made in order to negotiate survival. The thesis builds on Eickelman and Salvatore's (2006:97-104), concept of Public Islam which says that there is no singular concept of Islam, but rather a multiplicity of overlapping fonns of practice and discourse that represent the varied historical and political trajectories of the Muslim communities and their links and influences with societies elsewhere. The analysis is located in the realm of an emerging Muslim public sphere - a sphere which is constantly being redefined globally by changes in communication, travel and education, as well as competing ideas of politics and religion.
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Griffin, Marinda. "Reconstructing Identity with Urban Community Agriculture: How Refugees Confront Displacement, Food Insecurity, and Othering through Community Farming." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc984264/.
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Ethnic and religious conflict, and the deepening of capitalism have led to global diaspora at unprecedented levels. The United Nations High Commissioner for Refugees reported that as of 2015, 1 in every 122 persons worldwide were either a refugee, internally displaced, or seeking asylum. The U.S. currently admits the largest number of refugees worldwide. However, policies fail to reflect the multitude of elements that constitute successful resettlement. Moreover, many refugees come from farming backgrounds and are forced to migrate to a landless urban environment, where their skill sets may not be utilized and farm land is not available. I argue that existing resettlement processes are embedded in logics and practices that alienate humans from nature and from each other through competition, isolation, and placeless environments. Through an exploration in concepts of urban agriculture, place-making, identity, and otherness, and illuminating the experiences of resettled refugees involved in a community gardening project in Fort Worth, Texas, show how the urban refugee garden provides the individual a space to narrate an identity, and to resist industrial agriculture and labor outside their industry. Exploring best practices in resettlement should be a priority to governments, politicians, and communities involved in the process and highlight the reasons to advocate these types of resettlement alternatives.
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von, Hackwitz Kim, and Niklas Stenbäck. "Changing Landscapes – A GIS analysis of Neolithic site location and shore displacement in Eastern Central Sweden." Uppsala universitet, Institutionen för arkeologi och antik historia, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-200090.
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This article is an attempt to put forward the use of new digital techniques and data for understanding prehistoric landscapes. The starting point is that the specific characteristics of the landscape and of the sites included affect the interpretation. One character is the contemporary landscape and its topographies. Ancient landscapes can be successfully recreated digitally using GIS. By applying GIS methodology, a regression equation and new data, we reinvestigated an hypothesis proposed by Welinder in 1978 concerning the acculturation of the Pitted Ware Culture. The results indicate that a reconstruction of the landscape may alter the understanding of the Neolithic land use and the question of the relocation and termination of the Pitted Ware Culture at the end of Middle Neolithic B.
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Bonci, Tecla. "La reconstruction du mouvement du squelette : l'enjeu de l'artefact des tissus mous." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10056/document.
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Lors de l'analyse 3D du mouvement humain basée sur des marqueurs cutanés, la position des os ne peut être qu'indirectement estimée. Au cours d'une tâche, les déformations des tissus mous génèrent des déplacements des marqueurs par rapport à l'os : les artefacts de tissus mous (STA), entraînant des effets dévastateurs sur l'estimation de la position. La compensation des STA demeure une question ouverte. L'objectif de cette thèse est de contribuer à la solution de cette question cruciale. La modélisation des STA en utilisant des variables spécifiques mesurables est une condition préalable à son élimination. Un modèle corrigeant les trajectoires individuelles de marqueurs de la cuisse, calibré par des mesures directes des STA, est d'abord présenté. Les STA sont modélisés comme une combinaison linéaire des angles articulaires impliqués. Trois représentations des STA par une série de modes sont proposées : déplacements de marqueurs individuels, transformations géométriques de clusters de marqueurs (MCGT), et variations de forme de l'enveloppe de peau. Le MCGT permet de dissocier les composantes rigides et non rigides. Il a été démontré que seule la composante rigide affecte la cinématique articulaire. Un modèle de cette composante est alors défini pour les clusters cuisse et jambe. Un compromis acceptable entre la correction des STA et le nombre de paramètres a ainsi été obtenu. Les principales applications sont de générer une simulation réaliste des STA ; et surtout, en se concentrant sur la composante rigide, le modèle permet une reconstruction satisfaisante des STA avec moins de paramètres, ce qui facilite son incorporation dans un algorithme d'estimation de la position osseuseIn 3D human movement analysis performed using stereophotogrammetry and skin markers, bone pose can be only indirectly estimated. During a task, soft tissue deformations make the markers move with respect to the underlying bone generating soft tissue artefacts (STA), causing devastating effects on pose estimation and its compensation remains an open issue. The thesis’ aim was to contribute to the solution of this crucial issue. Modelling STA using measurable trial-specific variables is a prerequisite for its removal from marker trajectories. Two STA model architectures are proposed. A thigh marker-level model is first presented. STA was modeled as a linear combination of joint angles involved in the task. The model was calibrated with direct STA measures. The considerable number of model parameters led to defining STA approximations. Three definitions were proposed to represent STA as series of modes : individual marker displacements, marker-cluster geometrical transformations (MCGT), and skin envelope shape variations. Modes were selected using two criteria : modal energy and selecting them a priori. The MCGT allows to select either rigid or non-rigid components. It was also demonstrated that only the rigid component affects joint kinematics. A model of thigh and shank rigid component at cluster-level was then defined. An acceptable trade-off between STA compensation and number of parameters was obtained. These results lead to two main potential applications : generate realistic STAs for simulation
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Pereira, Pedro André Marques. "Measuring the strain of metallic surfaces in real time through vision systems." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/16447.
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Mestrado em Engenharia MecânicaVision systems have already proven to be a useful tool in various elds. The ease of their implementation, allied to their low cost mean that their growth potential is immense. In this dissertation it is proposed a approach to measure strains in metallic surfaces, using stereo vision. This approach is based on the 3D DIC. This method measures the strain of the surface by dividing this surface in small sections, called subsets, and iteratively nding the equation that describes its shape variation through time. However, calculating the transformation of this subset is very timeconsuming. The proposed approach tries to optimize this calculation by rst determine the displacement eld, and then the strain eld by derivation. The dissertation also presents some experimental data and practical considerations relatively to the camera setup and image equalization algorithms in order to obtain better disparity maps. The results were veri ed experimentally and compared with the results obtained from other softwares.
Os sistemas de vis~ao j a provaram ser uma ferramenta util em v arios campos. A facilidade da sua implementa c~ao, aliada ao seu baixo custo signi cam que o seu potencial de crescimento e enorme. Nesta disserta c~ao e proposta uma abordagem para medir deforma c~oes em superf cies met alicas usando vis~ao stereo. Esta abordagem e baseada na t ecnica 3D DIC. Este m etodo mede as deforma c~oes da superf cie dividindo-a em pequenas se c~oes, designadas por sub- sets, tentando iterativamente encontrar a equa c~ao que de ne as varia c~oes das suas formas ao longo do tempo. No entanto, o c alculo das transforma c~oes destes subsets e demorado. A abordagem proposta pretende pretende otimizar este c alculo determinando primeiro o campo de deslocamentos e depois o campo das deforma c~oes atrav es da deriva c~ao. A disserta c~ao apresenta tamb em dados experimentais e considera c~oes pr aticas relativamente a con gura c~ao (setup) das c^amaras e algoritmos de equaliza c~ao de imagens de forma a se obterem melhores mapas de disparidade. Os resultados foram veri cados experimentalmente e comparados com os resultados obtidos por outros softwares.
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Pham, Ha Thai. "Analyse de "Time Lapse" optiques stéréo et d'images radar satellitaires : application à la mesure du déplacement de glaciers." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAA004/document.
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L’observation de la Terre par des systèmes d’acquisition d’images permet de suivre l’évolution temporelle de phénomènes naturels tels que les séismes, les volcans ou les mouvements gravitaires. Différentes techniques existent dont l’imagerie satellitaire, la photogrammétrie terrestre et les mesures in-situ. Les séries temporelles d’images issues d’appareils photo automatiques (Time Lapse) sont une source d’informations en plein essor car elles offrent un compromis intéressant en termes de couverture spatiale et de fréquence d’observation pour mesurer les déplacements de surface de zones spécifiques. Cette thèse est consacrée à l’analyse de séries d’images issues de la photographie terrestre et de l’imagerie radar satellitaire pour la mesure du déplacement des glaciers Alpins. Nous nous intéressons en particulier aux problèmes du traitement de Time Lapse stéréo pour le suivi d’objets géophysiques dans des conditions terrain peu favorables à la photogrammétrie. Nous proposons une chaîne de traitement mono-caméra qui comprend les étapes de sélection automatique des images, de recalage et de calcul de champs de déplacement bidimensionnel (2D). L’information apportée par les couples stéréo est ensuite exploitée à l’aide du logiciel MICMAC pour reconstruire le relief et obtenir le déplacement tridimensionnel(3D). Plusieurs couples d’images radar à synthèse d’ouverture (SAR) ont également été traités à l’aide des outils EFIDIR pour obtenir des champs de déplacement 2D dans la géométrie radar sur des orbites ascendantes ou descendantes. La combinaison de mesures obtenues quasi-simultanément sur ces deux types d’orbites permet de reconstruire le déplacement 3D. Ces méthodes ont été mises en oeuvre sur des séries de couples stéréo acquis par deux appareils photo automatiques installés sur la rive droite du glacier d’Argentière et sur des images du satellite TerraSAR-X couvrant le massif du Mont-Blanc. Les résultats sont présentés sur des données acquises lors d’une expérimentation multi-instruments menée en collaboration avec l’IGN à l’automne 2013, incluant le déploiement d’un réseau de Géocubes qui ont fournit des mesures GPS. Elles sont utilisées pour évaluer la précision des résultats obtenus par télédétection proximale et spatiale sur ce type de glacierEarth observation by image acquisition systems allows the survey of temporal evolution of natural phenomena such as earthquakes, volcanoes or gravitational movements. Various techniques exist including satellite imagery, terrestrial photogrammetry and in-situ measurements. Image time series from automatic cameras (Time Lapse) are a growing source of information since they offer an interesting compromise in terms of spatial coverage and observation frequency in order to measure surface motion in specific areas. This PhD thesis is devoted to the analysis of image time series from terrestrial photography and satellite radar imagery to measure the displacement of Alpine glaciers. We are particularly interested in Time Lapse stereo processing problems for monitoring geophysical objects in unfavorable conditions for photogrammetry. We propose a single-camera processing chain that includes the steps of automatic photograph selection, coregistration and calculation of two-dimensional (2D) displacement field. The information provided by the stereo pairs is then processed using the MICMAC software to reconstruct the relief and get the three-dimensional (3D) displacement. Several pairs of synthetic aperture radar (SAR) images were also processed with the EFIDIR tools to obtain 2D displacement fields in the radar geometry in ascending or descending orbits. The combination of measurements obtained almost simultaneously on these two types of orbits allows the reconstruction of the 3D displacement. These methods have been implemented on time series of stereo pairs acquired by two automatic cameras installed on the right bank of the Argentière glacier and on TerraSAR-X satellite images covering the Mont-Blanc massif. The results are presented on data acquired during a multi-instrument experiment conducted in collaboration with the French Geographic National Institute (IGN) during the fall of 2013,with a network of Géocubes which provided GPS measurements. They are used to evaluate the accuracy of the results obtained by proximal and remote sensing on this type of glacier
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Arthington, Matthew Reginald. "Photogrammetric techniques for characterisation of anisotropic mechanical properties of Ti-6Al-4V." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:51e4f4d9-75e2-4784-9fbf-103d07496e23.
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The principal aims of this research have been the development of photogrammetric techniques for the measurement of anisotropic deformation in uniaxially loaded cylindrical specimens. This has been achieved through the use of calibrated cameras and the application of edge detection and multiple view geometry. The techniques have been demonstrated at quasi-static strain rates, 10^-3 s^-1, using a screw-driven loading device and high strain rates, 10^3 s^-1, using Split Hopkinson Bars. The materials that have been measured using the technique are nearlyisotropic steel, anisotropic cross-rolled Ti-6Al-4V and anisotropic clock-rolled commercially pure Zr. These techniques allow the surface shapes of specimens that deform elliptically to be completely tracked and measured in situ during loading. This has allowed the measurement of properties that could not have been recorded before, including true direct stress and the ratio of transverse strains in principal material directions, at quasi-static and elevated strain rates, in tension and compression. The techniques have been validated by measuring elliptical prisms of various aspect ratios and independently measuring interrupted specimens using a coordinate measurement machine. A secondary aim of this research has been to improve the characterisation of the anisotropic mechanical properties of cross-rolled Ti-6Al-4V using the techniques developed. In particular, the uniaxial yield stresses, hardening properties and the associated anisotropic deformation behaviour along the principal material directions, have all been recorded in detail not seen before. Significant findings include: higher yield stresses in-plane than in the through-thickness direction in both tension and compression, and the near transverse-isotropy of the through-thickness direction for loading conditions other than quasi-static tension, where significant anisotropy was observed.
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De, Donno Giulia. "Three dimensional strain analysis of vertebrae with artificial metastases through digital volume correlation." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/19911/.
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Bone is a common site for metastases and spine represent the most frequent site. Lytic lesions are associated with the loss of bone tissue, which can compromise the mechanical competence of the vertebra, leading to spine instability. Rigid stabilization is a solution, but it is a complex surgery, that can be very critical for oncologic patients; on the other hand, an untreated metastasis can lead to mechanical failure of the bone, leading to pain, immobilization and in the worst case, paralysis.
In this study, a protocol to analyse the strain with simulated lytic metastasis under compressive loading has been developed and optimized using a porcine vertebra. The strain distribution has been measured experimentally using micro-computed tomography (micro-CT) and Digital Volume Correlation (DVC), which provided three-dimensional displacements and strains maps inside the specimen. The ideal parameters for the DVC have been found by analysing two repeated scans in constant strain condition and setting a target of 200 microstrain for the errors (one order of magnitude lower than typical strains in bone subjected to physiological loading conditions). An ideal nodal spacing of 50 voxels (approximately 2 mm) has been chosen and a voxel detection algorithm has been applied to all data to remove regions outside the bone. In order to understand how the presence of the defect could alter the strain distribution, the porcine vertebra has also been subjected to non-destructive compressive load before and after the preparation of a mechanically induced lytic metastasis in the vertebral body. An increase of the 40% of the compressive principal strain after the defect has been found in proximity of the lesion.
This protocol will be used in future studies to analyse the effect of size and position of artificially metastatic lesions in the vertebral body of human spines.
Books on the topic "Displacements reconstruction"
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E, Powell Robert, Weldon R. J, and Matti Jonathan C, eds. The San Andreas fault system: Displacement, palinspastic reconstruction, and geologic evolution. Boulder, Colo: Geological Society of America, 1993.
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Carlin, Wendy. Economic reconstruction in Western Germany, 1945-55: The displacement of "vegetative control". London: University College, 1987.
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Gherlone, Marco. Dynamic shape reconstruction of three-dimensional frame structures using the inverse finite element method. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 2011.
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Al-Harithy, Howayda. Urban Recovery: Intersecting Displacement with Post War Reconstruction. Taylor & Francis Group, 2021.
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Al-Harithy, Howayda. Urban Recovery: Intersecting Displacement with Post War Reconstruction. Taylor & Francis Group, 2021.
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Al-Harithy, Howayda. Urban Recovery: Intersecting Displacement with Post War Reconstruction. Taylor & Francis Group, 2021.
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Al-Harithy, Howayda. Urban Recovery: Intersecting Displacement with Post War Reconstruction. Taylor & Francis Group, 2021.
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Chonka, Peter, and Jutta Bakonyi. Precarious Urbanism: Displacement, Dispossession and the Reconstruction of Somali Cities. Bristol University Press, 2022.
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The San Andreas Fault System: Displacement, Palinspastic Reconstruction, and Geologic Evolution. Geological Society of America, 1993. http://dx.doi.org/10.1130/mem178.
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E, Powell Robert, Weldon R. J. 1955-, and Matti Jonathan C, eds. The San Andreas fault system: Displacement, palinspastic reconstruction, and geologic evolution. Boulder, Colo: Geological Society of America, 1993.
Find full textBook chapters on the topic "Displacements reconstruction"
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Karácsonyi, Dávid, Kazumasa Hanaoka, and Yelizaveta Skryzhevska. "Long-Term Mass Displacements—The Main Demographic Consequence of Nuclear Disasters?" In The Demography of Disasters, 15–48. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-49920-4_2.
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Abstract Human history has witnessed several major disasters that have affected the economic, social and environmental conditions of their respective regions. The nuclear disaster of Chernobyl (1986, Ukraine, that time the Soviet Union) and Fukushima (2011, Japan) appears to be the most significant disasters in terms of negative outcomes produced for their population over a long time. Despite this, the analysis of the socio-economic outcomes of these disasters has attracted much less scientific attention than health or radiation-related issues (UNDP 2002a; Lehman and Wadsworth 2009, 2011). Although nuclear accidents are deemed to be rare events, the Fukushima disaster occurred only 25 years after Chernobyl. These disasters highlighted the need for a detailed long-term socio-economic analysis of these accidents to acquire sufficient knowledge to be applied when considering new construction sites for nuclear power facilities (Lehman and Wadsworth 2011). This chapter focuses on the problem of permanent resettlement resulting from nuclear disasters and its effects on regional demographic trajectories and spatial shifts. Based on the results of this study we argue that mass displacement after a nuclear disaster rather than the radiation itself has a much more significant impact on deteriorating health, natural reproduction and economic performance of the affected population. Furthermore, given the differences in radio-ecological conditions, reconstruction policy and the time framework, Fukushima may demonstrate demographic consequences that are different from the Chernobyl case.
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Walsh, Siun M., and Mahmoud El-Tamer. "Glandular Displacement Techniques." In Oncoplastic and Reconstructive Breast Surgery, 307–18. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-319-62927-8_24.
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Rietjens, Mario, Mario Casales Schorr, and Visnu Lohsiriwat. "Case36 Volume Displacement with Oncoplastic Technique." In Atlas of Breast Reconstruction, 331–39. Milano: Springer Milan, 2014. http://dx.doi.org/10.1007/978-88-470-5519-3_38.
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Rietjens, Mario, Mario Casales Schorr, and Visnu Lohsiriwat. "Case37 Volume Displacement with Oncoplastic Technique." In Atlas of Breast Reconstruction, 341–48. Milano: Springer Milan, 2014. http://dx.doi.org/10.1007/978-88-470-5519-3_39.
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Rietjens, Mario, Mario Casales Schorr, and Visnu Lohsiriwat. "Case38 Volume Displacement with Oncoplastic Technique." In Atlas of Breast Reconstruction, 349–52. Milano: Springer Milan, 2014. http://dx.doi.org/10.1007/978-88-470-5519-3_40.
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Rietjens, Mario, Mario Casales Schorr, and Visnu Lohsiriwat. "Case39 Volume Displacement with Oncoplastic Technique." In Atlas of Breast Reconstruction, 353–58. Milano: Springer Milan, 2014. http://dx.doi.org/10.1007/978-88-470-5519-3_41.
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Rietjens, Mario, Mario Casales Schorr, and Visnu Lohsiriwat. "Case40 Volume Displacement with Oncoplastic Technique." In Atlas of Breast Reconstruction, 359–64. Milano: Springer Milan, 2014. http://dx.doi.org/10.1007/978-88-470-5519-3_42.
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Rietjens, Mario, Mario Casales Schorr, and Visnu Lohsiriwat. "Case41 Volume Displacement with Oncoplastic Technique." In Atlas of Breast Reconstruction, 365–68. Milano: Springer Milan, 2014. http://dx.doi.org/10.1007/978-88-470-5519-3_43.
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Rietjens, Mario, Mario Casales Schorr, and Visnu Lohsiriwat. "Case42 Volume Displacement with Oncoplastic Technique." In Atlas of Breast Reconstruction, 369–81. Milano: Springer Milan, 2014. http://dx.doi.org/10.1007/978-88-470-5519-3_44.
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Rietjens, Mario, Mario Casales Schorr, and Visnu Lohsiriwat. "Case43 Volume Displacement with Oncoplastic Technique." In Atlas of Breast Reconstruction, 383–95. Milano: Springer Milan, 2014. http://dx.doi.org/10.1007/978-88-470-5519-3_45.
Full textConference papers on the topic "Displacements reconstruction"
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Li, Li, Ben S. Zhong, Zi Y. Geng, and Wei Sun. "Structural Shape Reconstruction of FBG Flexible Plate Using Modal Superposition Method." In ASME 2017 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/detc2017-67316.
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Structural shape reconstruction is a critical issue for real-time structural health monitoring in the fields of engineering application. This paper shows how to implement structural shape reconstruction using a small number of strain data measured by fiber Bragg grating (FBG) sensors. First, the basic theory of structural shape reconstruction is introduced using modal superposition method. A transformation is derived from the measured discrete strain data to global displacement field through modal coordinate, which is the same for strain mode shape superposition and displacement mode shape superposition. Then, optimization of the sensor layout is investigated to achieve the effective reconstruction effect. Finally, structural shape reconstruction algorithm using modal superposition method is applied in experiments. The experiment results show that the reconstructed displacements match well with those measured by a laser displacement sensor and the proposed approach is a promising method for structural shape reconstruction.
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Calle, S., M. E. Hachemi, and J. P. Remenieras. "P1A-1 An Alternative Technique of Displacements Synthetic Reconstruction in Transient Elastography." In 2006 IEEE Ultrasonics Symposium. IEEE, 2006. http://dx.doi.org/10.1109/ultsym.2006.308.
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Palmeri, Mark L., David Xu, Michael Wang, and Kathryn Nightingale. "Quantitative Images of Elastic Modulus Using Tissue Dynamics in the Region of Impulsive Acoustic Radiation Force Excitation." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-12695.
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Focused, impulsive, acoustic radiation force excitations can generate shear waves with microns of displacement in tissue. The speed of shear wave propagation is directly related to the tissue’s shear modulus, which can be correlated with tissue pathology to diagnose disease and to follow disease progression. Shear wave speed reconstruction has conventionally been measured over spatial domains that are spatially-offset from the region of excitation (ROE). While these methods are very robust in clinical studies characterizing large, homogeneous organs, their spatial resolution can be limited when generating quantitative images of shear elasticity. The ROETTP algorithm measures time-to-peak (TTP) displacements along the axis-of-symmetry in the ROE of an impulsive acoustic radiation force excitation. These TTP displacements are inversely proportional to shear stiffness and are dependent on the excitation-beam geometry. Lookup tables (LUTs) specific to an excitation/displacement tracking transducer configuration were generated from simulated data, and shear stiffnesses were estimated from experimental data as a function of depth using the LUTs. Quantitative ROETTP shear elasticity images of spherical inclusions in a calibrated tissue-mimicking phantom have been generated. Shear wave reflections and interference can lead to an underestimation of the absolute reconstructed shear modulus (20–25%), but the ratio of absolute shear stiffnesses is well-preserved (3.3 vs. 3.5).
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Shadlen, Michael, Thom Carney, Eugene Switkes, and Daniel Kersten. "Reconstruction of temporally undersampled images using motion direction information." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/oam.1988.fd3.
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Several problems posed by spatial and temporally sampled moving images may be ameliorated when knowledge of visual motion direction is known. We extend prior analyses of sampled moving images through the following conjecture. For rigid motion in one direction, the image spatiotemporal Fourier transform is a surface which occupies only two diagonal quadrants of the spatiotemporal frequency plane. Although sampling introduces energy to all four quadrants, that which falls over the wrong diagonal quadrants is likely to be more detrimental to motion perception, since the energy tends to excite motion detectors signaling an incorrect direction. If the direction of motion is known at every point in an image, temporally undersampled images may be partially reconstructed by removing this incorrect energy. This conjecture serves to explain the demise of short-range motion perception at large displacements and interstimulus intervals. It also explains motion capture phenomena, cooperativity, and the coherence of sampled motion displays containing elements which are effectively undersampled.
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Peng, Hui, and Henry Stark. "Efficient estimation of the shape of opacities in computed tomography." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1987. http://dx.doi.org/10.1364/oam.1987.tuh2.
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The limited data problem in tomography refers to two situations: (1) the limited angular view problem where the source and/or detectors are prevented from reaching certain angular displacements and (2) the inability to get a full set of meaningful data because of internal opacities in the object being examined. We address the second situation and show how the size and shape of the convex hull of the opaque object can be estimated from a few measurements. Indeed if only the size and shape of the opacity are required, only O(N) operations (one operation is one addition plus one multiplication) are required as opposed to O(N3) for convolution backprojection reconstruction or O(N2 logN) for direct Fourier inversion. Moreover the signal processing operations required to estimate the opacity are much less complicated than those required in image reconstruction.
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McNeill, Scot, Tomokazu Saruhashi, Ikuo Sawada, Masanori Kyo, Eigo Miyazaki, and Yasuyuki Yamazaki. "A Method for Estimating Quasi-Static Riser Deformation and Applied Forces From Sparse Riser Inclination Measurements." In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41286.
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A method was recently presented for determining quasi-static and dynamic riser angles using measured data typically found in a riser fatigue monitoring system, specifically acceleration and angular rate data. The riser angles were determined at sensor locations. In this paper quasi-static riser displacement, inclination angle, curvature, and stress are estimated along the entire length of the riser, using only the quasi-static inclinations angles at sparse sensor locations. In addition the distribution of applied forces along the entire riser length is also estimated. A rough representation of the current profile can be calculated using the drag coefficients of riser joints. The riser deformation (displacement, inclination, curvature) and applied forces are estimated by solving the matrix equation f = K*x, where f is the vector of forces and moments, K is the stiffness matrix and x is the vector of displacements and inclination angles. In the equation, force and displacement vectors are unknown and the stiffness matrix is determined using Finite Element (FE) modeling. Constraints are applied, setting the inclination angle at the sensor locations to the values derived from measured data. The remaining highly-underdetermined problem cannot be solved in a classical sense, as it admits infinite solutions. To get a solution that is consistent with the physics of riser deformation, smoothness of the solution is enforced as a constraint. The smoothest solution is solved using quadratic programming methods. Following implementation of the method in Matlab®, the procedure was validated using numerical simulations of a riser in applied current. Both connected (to the wellhead) and disconnected cases were simulated. Estimated riser displacements, slopes, curvatures and applied forces are found to match the simulation results closely. The algorithm was then run using measured data from an emergency disconnect event that occurred on the Chikyu drill ship in November, 2012. The riser displacement, inclination and curvature were determined and found to agree well with results determined using another method. The additional capabilities presented herein further expand the utility of a riser monitoring system. Quasi-static and dynamic riser angles are derived from acceleration and angular rate sensors using previously published methods. Using the method developed herein, the quasi-static inclination angles at the sensor locations can be used to determine the displacement, inclination, curvature (stress) and even applied force along the entire riser. These results are particularly useful in strength assessment, model verification, clashing and emergency event reconstruction analyses.
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Koguchi, Hideo, and Naoki Nishi. "Contact Analysis Using Surface Green’s Functions for Isotropic Materials With Surface Stress and Surface Elasticity." In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-37814.
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Surface stress and surface elasticity are related to an organization of surface pattern and reconstruction of surface atoms. When the size of material reduces to a nanometer level, a ratio of surface to volume increases. Then, surface stress and surface elasticity influence on mechanical response near surface for an external force on the surface. Stroh formalism is very useful for analyzing the stress and displacement in anisotropic materials. When the Stroh’s formalism is applied to isotropic materials, the eigen matrix derived from equilibrium equation yields a triple root of i (i: imaginary unit), and then an independent eigen vector corresponding to the eigen value can not be determined. In this paper, surface Green function for isotropic materials is derived using Stroh’s formalism. The derived Green function considering neither surface stress nor surface elasticity agrees with the solution of Boussinesq. The surface Green’s function considering surface stress and surface elasticity is used for analyzing the displacement fields in amorphous silicon. It was found that the displacements obtained from the Green’s function were less than those from Boussinesq’s solution. Furthermore, the derived surface Green’s function is applied to a contact analysis for isotropic materials such as amorphous silicon. It is found that an apparent Young’s modulus determined from a force-indentation depth curve increases when surface stress and elasticity is taken into account in the analysis.
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Weiss, Shimon. "Dual-molecule fluorescence spectroscopy: kinetic observation of single molecule reactions." In Laser Applications to Chemical and Environmental Analysis. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/lacea.1998.lma.6.
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Traditional structural biology ensemble techniques such as x-ray crystallography, electron cryomicroscopy with angular reconstruction, electron microscopy, nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) provide detailed information on the structure of biological macromolecules. In cases where the crystal form of the macromolecule is available, the structure is known with the ultimate atomic resolution. The knowledge of the static structure can provide some insight to the macromolecule function, especially if it is coupled with other biochemical measurements, but in general the structure-function relationship is to a large extent unknown. With the aid of recently developed techniques such as patch clamp, atomic force microscopy (AFM) and optical tweezers, ionic current fluctuations in individual ion channels and forces and/or displacements generated during single molecular motor reaction were measured. Such measurements furnish information about function, but do not provide local, dynamical structural information.
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Agrawal, Ayush, Hesham M. Zaini, Tony Dear, and Howie Choset. "Experimental Gait Analysis of Waveboard Locomotion." In ASME 2016 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/dscc2016-9923.
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Through modeling and experimentation, we analyze common gaits on a waveboard, an underactuated mechanical system whose motion is governed by both nonholonomic constraints and momentum conservation. We take advantage of the system’s symmetries to derive a reduced system model that differentiates between kinematic and dynamic components of motion. We evaluate this model using marker trajectory data gathered through an optical tracking system for various types of gaits. By extracting relevant trajectory parameters via state reconstruction and fitting our joint variables to an ellipse, we determine the kinematic components of gaits commonly used by human riders. In particular, we demonstrate that traditional forward motion is purely dynamic, while sustained turning motion contains kinematic components. In order to validate our model, we compare experimentally obtained trajectories with reconstructed displacements based on the model. Finally, we suggest an approach for further analysis of the dynamic components of these gaits.
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Pomadere, Marie, Erwan Liberge, Aziz Hamdouni, Elisabeth Longatte, and Jean-François Sigrist. "Numerical Study of Fluid-Structure Interactions in Tube Bundles With Multiphase-POD Reduced-Order Approach." In ASME 2012 11th Biennial Conference on Engineering Systems Design and Analysis. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/esda2012-82462.
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Fluid-Structure Interactions are present in a large number of systems of nuclear power plants and nuclear on-board stoke-holds. Particularly in steam generators, where tube bundles are submitted to cross-flow which can lead to structure vibrations. We know that numerical studies of such a complex mechanism is very costly, that is why we propose the use of reduced-order methods in order to reduce calculation times and to make easier parametric studies for such problems. We use the multiphase-POD approach, initially proposed by Liberge (E. Liberge; POD-Galerkin Reduction Models for Fluid-Structure Interaction Problems, PhD Thesis, Universite de La Rochelle, 2008). This method is an adaptation of the classical POD approach to the case of a moving structure in a flow, considering the whole system (fluid and structure) as a multiphase domain. We are interested in the case of large displacements of a structure moving in a fluid, in order to observe the ability of the multiphase-POD technique to give a satisfying solution reconstruction. We obtain very interesting results for the case of a single circular cylinder in cross-flow (lock-in phenomenon). Then we present the application of the method to a case of confined cylinders in large displacements too. Here again, results are encouraging. Finally, we propose to go further presenting a first step in parametric studies with POD-Galerkin approach. We only consider a flowing-fluid around a fixed structure and the Burgers’ equation. A future work will consist in applications to fluid-structure interactions.
Reports on the topic "Displacements reconstruction"
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Chensvert, Thomas L. NMR Reconstructive Elasticity Imaging of Breast: Surrogate Remote Palpation Using Quantitative 3-D Displacement and Strain Estimations. Fort Belvoir, VA: Defense Technical Information Center, September 1999. http://dx.doi.org/10.21236/ada391282.
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