Статті в журналах: "Deformation retractions"

1

Goodykoontz, Jack T. "Some retractions and deformation retractions on 2x and C(X)." Topology and its Applications 21, no. 2 (November 1985): 121–33. http://dx.doi.org/10.1016/0166-8641(85)90099-9.

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2

El-Ahmady, A. E. "Foldings and Deformation Retractions of Hypercylinder." Indian Journal of Science and Technology 6, no. 2 (February 20, 2013): 1–10. http://dx.doi.org/10.17485/ijst/2013/v6i2.23.

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3

Pflaum, Markus J., and Graeme Wilkin. "Equivariant control data and neighborhood deformation retractions." Methods and Applications of Analysis 26, no. 1 (2019): 13–36. http://dx.doi.org/10.4310/maa.2019.v26.n1.a2.

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4

El-Ahmady, A. E., and A. T. M-Zidan. "On the Deformation Retractions of Frenet Curves in Minkowski 4 - Space." Modern Applied Science 14, no. 9 (August 28, 2020): 55. http://dx.doi.org/10.5539/mas.v14n9p55.

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In this paper, the position vector equation of   the Frenet curves with constant curvatures in Minkowski 4 -space has been presented. New types for retractions and deformation retracts of Frenet curves in  are deduced. The relations between the Frenet apparatus of the Frenet curves before and after the deformation retracts are obtained.

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5

Talafha, Adeeb G., Sahar M. Alqaraleh, A. E. El-Ahmady, and Jehad Al Jaraden. "On Fuzzy Fundamental Groups and Fuzzy Folding of Fuzzy Minkowski Space." Advances in Fuzzy Systems 2021 (August 14, 2021): 1–9. http://dx.doi.org/10.1155/2021/7747394.

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In this paper, we studied the relations between new types of fuzzy retractions, fuzzy foldings, and fuzzy deformation retractions, on fuzzy fundamental groups of the fuzzy Minkowski space M ˜ 4 . These geometrical transformations are used to give a combinatorial characterization of the fundamental groups of fuzzy submanifolds on M ˜ 4 . Then, the fuzzy fundamental groups of the fuzzy geodesics and the limit fuzzy foldings of M ˜ 4 are presented and obtained. Finally, we proved a sequence of theorems concerning the isomorphism between the fuzzy fundamental group and the fuzzy identity group.

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6

Bagchi, Susmit. "Constructions and Properties of Quasi Sigma-Algebra in Topological Measure Space." Axioms 11, no. 9 (August 24, 2022): 425. http://dx.doi.org/10.3390/axioms11090425.

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The topological views of a measure space provide deep insights. In this paper, the sigma-set algebraic structure is extended in a Hausdorff topological space based on the locally compactable neighborhood systems without considering strictly (metrized) Borel variety. The null extension gives rise to a quasi sigma-semiring based on sigma-neighborhoods, which are rectifiable in view of Dieudonné measure in n-space. The concepts of symmetric signed measure, uniformly pushforward measure, and its interval-valued Lebesgue variety within a topological measure space are introduced. The symmetric signed measure preserves the total ordering on the real line; however, the collapse of symmetry admits Dieudonné measure within the topological space. The locally constant measures in compact supports in sigma-neighborhood systems are invariant under topological deformation retraction in a simply connected space where the sequence of deformation retractions induces a strongly convergent sequence of measures. Moreover, the extended sigma-structures in an automorphic and isomorphic topological space preserve the properties of uniformly pushforward measure. The Haar-measurable group algebraic structures equivalent to additive integer groups arise under the locally constant and signed measures as long as the topological space is non-compact and the null-extended sigma-neighborhood system admits compact groups. The comparative analyses of the proposed concepts with respect to existing results are outlined.

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7

Abu-Saleem, M. "The minimum deformation retract on the wormhole spacetime." International Journal of Geometric Methods in Modern Physics 17, no. 13 (October 13, 2020): 2050198. http://dx.doi.org/10.1142/s0219887820501984.

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In this paper, we investigate the topology of a wormhole from the viewpoint of the theory of retracting and var-folding. We deduce the equatorial geodesics on the line element of the wormhole and discuss the minimum deformation retract related to this space. Using the Lagrangian equations we find that there is a type of minimum retraction of a wormhole with associated topology. We also extend the result to the [Formula: see text]-dimensional wormhole and show that the end limit of var-folding is 0-dimensional wormhole and obtain the relation between limit var-folding and limit retraction. We find a new application in geometric topology and astrophysics.

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8

Ahmed, Nasr, and H. Rafat. "Existence of deformations and dimensional reduction in wormholes and black holes." International Journal of Geometric Methods in Modern Physics 15, no. 11 (November 2018): 1850197. http://dx.doi.org/10.1142/s0219887818501979.

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The deformation retract is, by definition, a homotopy between a retraction and the identity map. We show that applying this topological concept to Ricci-flat wormholes/black holes implies that such objects can get deformed and reduced to lower dimensions. The homotopy theory can provide a rigorous proof to the existence of black holes/wormholes deformations and explain the topological origin. The current work discusses such possible deformations and dimensional reductions from a global topological point of view, it also represents a new application of the homotopy theory and deformation retract in astrophysics and quantum gravity.

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9

Garland, Michael GC, Matthew J. Santer, and Jonathan F. Morrison. "Optimal aero-structural design of an adaptive surface for boundary layer motivation using an auxetic lattice skin." Journal of Intelligent Material Systems and Structures 28, no. 17 (February 6, 2017): 2414–27. http://dx.doi.org/10.1177/1045389x16685446.

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The aero-structural design of an adaptive vortex generator for repeatable, elastic, deployment and retraction from an aerodynamically clean surface is presented. A multidisciplinary objective function, containing geometrically nonlinear finite element analysis and large eddy simulation, is used to derive the optimal adaptive geometry for increasing the momentum of the near-wall fluid. It is found that the rapid increase of in-plane membrane stress with deflection is a significant limitation on achievable deformation of a continuous skin with uniform section. Use of a 2D auxetic lattice structure in place of the continuous skin allows for significantly larger deformations and thus a significant improvement in performance. The optimal deformed geometry is replicated statically and the effect on the boundary layer is validated in a wind tunnel experiment. The lattice structure is then manufactured and actuated. The deformed geometry is shown to compare well with the FEA predictions. The surface is re-examined post actuation and shown to return to the initial position, demonstrating the deformation is elastic and hence repeatable.

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10

He, Huan An, and You Gang Wang. "Research on Long-Term Expansive Deformation of Steel Fiber Reinforced Expansive Concrete." Key Engineering Materials 417-418 (October 2009): 945–48. http://dx.doi.org/10.4028/www.scientific.net/kem.417-418.945.

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The inherent low tensile strength and shrinkage result in cracking of concrete under work loads. A new way to improve cracking properties is distributing steel fibers into expansive concrete to form a type of composite which is called steel fiber reinforced expansive concrete. This type of high performance concrete could compensate shrinkage as well as improving crack strength. For this concrete, the key point to ensure high performance and safety of concrete structure is to keep a stable expansive deformation during long-term service. A series of tests were carried out to measure long-term restrained expansive deformations of steel fiber reinforced expansive concrete with ages under various restrictions like steel bars and steel fibers. The test investigated some 3-year specimens. For all specimens, test parameters included 2 ratios of steel bar reinforcement, 4 volume fractions of steel fiber and 4 dosages of expansion admixture. The test results showed that the expansion of concrete decreased with increasing of steel bar reinforcing ratio as well as steel fiber volume fraction. In addition, when being in a lower dosage of expansion admixture, the specimens presented remarkable retraction of the expansive deformation. However, when beyond a certain dosage of expansion admixture, the long-term expansive deformation had less change with ages and almost remained the same with 90-day deformation, namely less losses of deformation. Hence, for steel fiber reinforced expansive concrete, using an appropriate dosage of expansion admixture could meet the requirements of designed strengthening and compensating shrinkage.

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11

Meurer, Michael, Tim Prescher, Esther Ramakers-van Dorp, Bernhard Möginger, and Berenika Hausnerova. "RheoTack—An approach to investigate retraction rate dependent detaching behavior of pressure sensitive adhesives." Journal of Rheology 66, no. 3 (May 2022): 505–14. http://dx.doi.org/10.1122/8.0000405.

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Characterization methods of pressure sensitive adhesives (PSA) originate from technical bonding and do not cover relevant data for the development and quality assurance of medical applications, where PSA with flexible backing layers are adopted to human skin. In this study, a new method called RheoTack is developed to determine (mechanically and optically) an adhesion and detaching behavior of flexible and transparent PSA based patches. Transdermal therapeutic systems (TTS) consisting of silicone-based PSAs on a flexible and transparent backing layer were tested on a rotational rheometer with an 8 mm plate as a probe rod at retraction speeds of 0.01, 0.1, and 1 mm/s with respect to their adhesion and detaching behavior in terms of force-retraction displacement curves. The curves consist of a compression phase to affirm wetting; a tensile deformation phase intercepting stretching, cavity, and fibril formation; and a failure phase with detaching. Their analysis provides values for stiffness, force, and displacement of the beginning of fibril formation, force and displacement of the beginning of a failure due to fibril breakage and detaching, as well as corresponding activation energies. All these parameters exhibit the pronounced dependency on the retraction speed. The force-retraction displacement curves together with the simultaneous video recordings of the TTS deformation from three different angles (three cameras) provide deeper insight into the deformation processes and allow for interpreting the properties’ characteristics for PSA applications.

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12

Zhu, Cheng, Richard Skalak, and Geert W. Schmid-Scho¨nbein. "One-Dimensional Steady Continuum Model of Retraction of Pseudopod in Leukocytes." Journal of Biomechanical Engineering 111, no. 1 (February 1, 1989): 69–77. http://dx.doi.org/10.1115/1.3168342.

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A one-dimensional steady state continuum mechanics model of retraction of pseudopod in leukocytes is developed. The retracting pseudopod is assumed to move bodily toward the main cell body, the bulk motion of which can be represented by cytoplasmic flow within a typical stream tube through the leukocyte. The stream tube is approximated by a frictionless tube with prescribed geometry. The passive rheological properties of cytoplasm in the main cell body and in the pseudopod are modeled, respectively, by Maxwell fluid and Hookean solid. The two regions are assumed to be separated by a sharp interface at which actin gel solates and thereby changes its rheological properties as it flows from the pseudopod to the main cell body. The driving mechanism responsible for the active retraction motion is hypothesized to be a spontaneous deformation of the actin gel, analogous but not necessarily equal to the well known actin-myosin interaction. This results in an active contractile stress being developed in the pseudopod as well as in the cell cortex. The transverse traction pulls against the inclined wall of the stream tube and is transduced into an axial stress gradient, which in turn drives the flow. The tension on the tube wall is picked up by the prestressed cortical shell. Governing equations and boundary conditions are derived. A solution is obtained. Sample data are computed. Comparison of the theory with experiments shows that the model is compatible to the observations.

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13

Rafat, H., and Nasr Ahmed. "On the Deformation Retract of Eguchi-Hanson Space and Its Folding." Advances in Mathematical Physics 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/301928.

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We introduce the deformation retract of the Eguchi-Hanson space using Lagrangian equations. The retraction of this space into itself and into geodesics has been presented. The deformation retract of the Eguchi-Hanson space into itself and after the isometric folding has been discussed. Theorems concerning these relations have been deduced.

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14

Rafat, H. "On the Deformation Retract of Kerr Spacetime and Its Folding." Advances in Mathematical Physics 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/673768.

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The deformation retract of the Kerr spacetime is introduced using Lagrangian equations. The equatorial geodesics of the Kerr space have been discussed. The retraction of this space into itself and into geodesics has been presented. The deformation retract of this space into itself and after the isometric folding has been discussed. Theorems concerning these relations have been deduced.

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15

Almusallam, Abdulwahab S., Isameldeen E. Daffallah, and Lazhar Benyahia. "Modeling the Deformation of Shear Thinning Droplets Suspended in a Newtonian Fluid." Applied Rheology 30, no. 1 (January 1, 2020): 151–65. http://dx.doi.org/10.1515/arh-2020-0113.

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Abstract In this work, we carried out numerical modeling of the large deformation of a shear thinning droplet suspended in a Newtonian matrix using the constrained volume model. The adopted approach was to consider making incremental corrections to the evolution of the droplet anisotropy equation in order to capture the experimental behavior of a shear thinning droplet when subjected to deformation due to imposed flow. The constrained volume model was modified by using different models to describe the viscosity of droplet phase: the Bautista et al. model, the Carreau-Yasuda model and the Power-law model. We found that by combining the constrained volume model with a simple shear thinning viscosity model we were able to describe the available experimental data for large deformation of a shear thinning droplet suspended in a Newtonian matrix. Moreover, we developed an equation approximating flow strength during droplet retraction, and we found that the model can accurately describe the experimental data of the retraction of a shear thinning droplet.

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16

Ghosh, Ranajay, Aloke Kumar, and Ashkan Vaziri. "Type-IV Pilus Deformation Can Explain Retraction Behavior." PLoS ONE 9, no. 12 (December 12, 2014): e114613. http://dx.doi.org/10.1371/journal.pone.0114613.

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17

Bakhtiari, A., and I. Berenjani. "Texture, microhardness and corrosion resistance of 316L stainless steel." Metallurgical and Materials Engineering 21, no. 1 (March 31, 2015): 1–6. http://dx.doi.org/10.30544/127.

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The texture, microhardness, and corrosion resistance of cold worked 316L steel were evaluated. The X-ray diffraction analysis in particular permitted to disclose and identify the main textures variations in the structure of the investigated steel after its deformation within the range 10 - 80%. The corrosion resistance was studied using Tafel polarization tests. It was shown that the increase in deformation degree drastically decreases the relative intensity of {111} planes. Besides, with high degree of cold deformation microhardness increases while corrosion resistance deteriorates. This article has been retracted. Link to the retraction

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18

Watanabe, Y., and D. M. Ingram. "Transverse instabilities of ascending planar jets formed by wave impacts on vertical walls." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 471, no. 2182 (October 2015): 20150397. http://dx.doi.org/10.1098/rspa.2015.0397.

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When a steep breaking wave hits a vertical sea wall, in shallow water, a rapidly ascending planar jet forms. This jet is ejected with high acceleration due to pressure created by the violent wave impact on the wall, creating a so-called ‘flip-through’ event. Previous studies have focused on the impulsive pressures on, and within, the wall and on the velocity of the jet. Here, in contrast, we consider the formation and break-up of the jet itself. Experiments show that during flip-through a fluid sheet, bounded by a rim, forms. This sheet has unstable transitional behaviours and organizing jets; undulations in the thickness of the fluid sheet are rapidly amplified and ruptured into an array of vertical ligaments. Lateral undulations of the rim lead to the formation of finger-jets, which subsequently break up to form droplets and spray. We present a linear stability analysis of the rim–sheet systems that highlights the contributions of rim retraction and sheet stretching to the break-up process. The mechanisms for the sequential surface deformations in the rim–sheet system are also described. Multiple, distinct, instability modes are identified during the rim deceleration, sheet stretch attenuation and rim retraction processes. The wavenumbers (and deformation length scales) associated with these instability modes are shown to lead to the characteristic double peak spectrum of surface displacement observed in the experiments. These mechanisms help to explain the columnar structures often seen in photographs of violent wave impacts on harbour walls.

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19

Gatsutsyn, V. V., A. E. Nalivkin, V. A. Kuzmichev, Aleksandr E. Mashkov, and D. A. Pykhteev. "THE SUBSTANTIATION OF THE DIFFERENTIATED APPROACH IN DIAGNOSTICS AND SURGICAL CORRECTION OF THE FUNNEL-SHAPED DEFORMATION OF THE CHEST IN CHILDREN." Russian Journal of Pediatric Surgery 22, no. 4 (October 9, 2018): 199–204. http://dx.doi.org/10.18821/1560-9510-2018-22-4-199-204.

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Funnel-shaped deformation of the chest (pectus excavalus) is a congenital pathology of the anterior thoracic wall, manifested by the retraction of the sternum and sternocostal cartilages in various forms and degrees. There are many options for correcting this deformation, which can be conditionally divided into open and minimally invasive methods. In the leading clinics for this pathology, there is recently used the most minimally invasive method of correction by Nass. Unfortunately, for today there is no the only as an algorithm for preoperative examination of patients with this pathology, as well as the decision on the choice of surgical correction method.

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20

Montuelle, Stéphane J., Rachel A. Olson, Hannah Curtis, and Susan H. Williams. "Unilateral lingual nerve transection alters jaw-tongue coordination during mastication in pigs." Journal of Applied Physiology 128, no. 4 (April 1, 2020): 941–51. http://dx.doi.org/10.1152/japplphysiol.00398.2019.

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During chewing, movements and deformations of the tongue are coordinated with jaw movements to manage and manipulate the bolus and avoid injury. Individuals with injuries to the lingual nerve report both tongue injuries due to biting and difficulties in chewing, primarily because of impaired bolus management, suggesting that jaw-tongue coordination relies on intact lingual afferents. Here, we investigate how unilateral lingual nerve (LN) transection affects jaw-tongue coordination in an animal model (pig, Sus scrofa). Temporal coordination between jaw pitch (opening-closing) and 1) anteroposterior tongue position (i.e., protraction-retraction), 2) anteroposterior tongue length, and 3) mediolateral tongue width was compared between pre- and post-LN transection using cross-correlation analyses. Overall, following LN transection, the lag between jaw pitch and the majority of tongue kinematics decreased significantly, demonstrating that sensory loss from the tongue alters jaw-tongue coordination. In addition, decrease in jaw-tongue lag suggests that, following LN transection, tongue movements and deformations occur earlier in the gape cycle than when the lingual sensory afferents are intact. If the velocity of tongue movements and deformations remains constant, earlier occurrence can reflect less pronounced movements, possibly to avoid injuries. The results of this study demonstrate that lingual afferents participate in chewing by assisting with coordinating the timing of jaw and tongue movements. The observed changes may affect bolus management performance and/or may represent protective strategies because of altered somatosensory awareness of the tongue. NEW & NOTEWORTHY Chewing requires coordination between tongue and jaw movements. We compared the coordination of tongue movements and deformation relative to jaw opening-closing movements pre- and post-lingual nerve transection during chewing in pigs. These experiments reveal that the timing of jaw-tongue coordination is altered following unilateral disruption of sensory information from the tongue. Therefore, maintenance of jaw-tongue coordination requires bilateral sensory information from the tongue.

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21

Sabourau, Stéphane. "Strong deformation retraction of the space of Zoll Finsler projective planes." Journal of Symplectic Geometry 17, no. 2 (2019): 443–76. http://dx.doi.org/10.4310/jsg.2019.v17.n2.a5.

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22

Wu, JingTao, PeiQiang Tian, Zhu Cheng, and WenLiang Deng. "Analysis of retraction performance of aircraft landing gear in high and low temperature environment." Journal of Physics: Conference Series 2252, no. 1 (April 1, 2022): 012027. http://dx.doi.org/10.1088/1742-6596/2252/1/012027.

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Abstract In order to solve the problem that the internal mechanism parameters of the aircraft landing gear are difficult to measure and retractable, the retractable performance of the landing gear under high and low temperature environments is studied. This paper simplifies the retractable mechanism of the landing gear by analyzing the motion mechanism of the aircraft landing gear. The degree of freedom of the retractable mechanism is calculated to verify the accuracy of the simplified rear landing gear retraction mechanism. The simulation model of landing gear retraction mechanism under high and low temperature environment is constructed by Patran. The component deformation and shaft clearance of the retractable mechanism under low temperature (-55°C) and high temperature (74°C) environments are analyzed from the overall and detail dimensions. The quantitative effect of ambient temperature on the deformation of the retractable mechanism of the landing gear is studied. Then Adams is used to establish the kinematics simulation model of the retractable mechanism, and the friction coefficient of the kinematic pair under different ambient temperatures is incorporated. Based on the historical data of the high and low temperature environmental test of the landing gear, the correctness of the model is verified. The influence of the environmental temperature on the driving torque, movement angle and movement time of the retractable mechanism is quantified. The problem that the deformation parameters and motion characteristics of the retractable mechanism of the landing gear are difficult to measure is solved, and the research method of retractable performance of the landing gear mechanism under different ambient temperatures is formed.

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23

Wu, JingTao, PeiQiang Tian, Zhu Cheng, and WenLiang Deng. "Analysis of retraction performance of aircraft landing gear in high and low temperature environment." Journal of Physics: Conference Series 2252, no. 1 (April 1, 2022): 012027. http://dx.doi.org/10.1088/1742-6596/2252/1/012027.

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Анотація:

Abstract In order to solve the problem that the internal mechanism parameters of the aircraft landing gear are difficult to measure and retractable, the retractable performance of the landing gear under high and low temperature environments is studied. This paper simplifies the retractable mechanism of the landing gear by analyzing the motion mechanism of the aircraft landing gear. The degree of freedom of the retractable mechanism is calculated to verify the accuracy of the simplified rear landing gear retraction mechanism. The simulation model of landing gear retraction mechanism under high and low temperature environment is constructed by Patran. The component deformation and shaft clearance of the retractable mechanism under low temperature (-55°C) and high temperature (74°C) environments are analyzed from the overall and detail dimensions. The quantitative effect of ambient temperature on the deformation of the retractable mechanism of the landing gear is studied. Then Adams is used to establish the kinematics simulation model of the retractable mechanism, and the friction coefficient of the kinematic pair under different ambient temperatures is incorporated. Based on the historical data of the high and low temperature environmental test of the landing gear, the correctness of the model is verified. The influence of the environmental temperature on the driving torque, movement angle and movement time of the retractable mechanism is quantified. The problem that the deformation parameters and motion characteristics of the retractable mechanism of the landing gear are difficult to measure is solved, and the research method of retractable performance of the landing gear mechanism under different ambient temperatures is formed.

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24

Raboud, D. "Simulation of the Superelastic Response of SMA Orthodontic Wires." Journal of Biomechanical Engineering 120, no. 5 (October 1, 1998): 676–85. http://dx.doi.org/10.1115/1.2834761.

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Shape-memory alloys have properties that make them well suited to a variety of applications. One application for which their unique combination of properties (large elastic range, low modulus of elasticity, ability to deliver nearly constant forces over a wide range of deformations) seems ideally suited is for orthodontic retraction appliances where these properties are very desirable. The mechanical response of shape-memory alloys is modeled by a simple constitutive model that captures the essential superelastic behavior of the shape-memory wires. An initial value approach that iteratively converges to the appropriate boundary conditions is utilized to deliver numerical solutions. Qualitative agreement is shown with previous experimental works. The possible benefits of using such wires in an orthodontic retraction appliance are then investigated.

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25

Sutera, S. P., E. R. Mueller, and G. I. Zahalak. "Extensional Recovery of an Intact Erythrocyte From a Tank-Treading Motion." Journal of Biomechanical Engineering 112, no. 3 (August 1, 1990): 250–56. http://dx.doi.org/10.1115/1.2891181.

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Normal human erythrocytes suspended in shear flow are stretched into quasi ellipsoidal forms while their membranes rotate smoothly (tank-treading). Following abrupt cessation of shear the cells recover their discoidal shapes approximately exponentially, in the manner of a Kelvin-Voigt (K-V) solid. To test the hypothesis that the recovery process is membrane-controlled, the effects of initial deformation, cytoplasmic viscosity and membrane surface-to-volume ratio were studied. It was concluded that the membrane dynamics dominates the transient shape recovery, and that the characteristic recovery time is dependent on the initial deformation. Hence, the usual simplified analysis based on retraction of a plane sheet of K-V material with constant moduli appears to be an inadequate treatment of transient whole cell recovery.

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26

Ye, Fu Li, and Gui Lian Shi. "Research on Episode Segmentation for MIS Workflow." Applied Mechanics and Materials 599-601 (August 2014): 2120–24. http://dx.doi.org/10.4028/www.scientific.net/amm.599-601.2120.

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In this paper, a Bayesian method for fusing multiple visual cues is proposed for MIS (Minimally Invasive Surgery) workflow segmentation. The proposed technique investigates the characteristics of four basic events in MIS including idle, retraction, cauterisation and suturing. Visual cues related to shape, deformation, changes in light reflection, and other low level image features are fused using a Bayesian framework to achieve a high classification accuracy. Detailed in vivo experiments have been conducted to assess the accuracy and practical value of the technique.

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27

Ichimura, Koichiro, Takayuki Miyaki, Yuto Kawasaki, Mui Kinoshita, Soichiro Kakuta, and Tatsuo Sakai. "Morphological Processes of Foot Process Effacement in Puromycin Aminonucleoside Nephrosis Revealed by FIB/SEM Tomography." Journal of the American Society of Nephrology 30, no. 1 (December 4, 2018): 96–108. http://dx.doi.org/10.1681/asn.2018020139.

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BackgroundFoot process effacement is one of the pathologic indicators of podocyte injury. However, the morphologic changes associated with it remain unclear.MethodsTo clarify the developmental process, we analyzed puromycin nephrotic podocytes reconstructed from serial focused-ion beam/scanning electron microscopy (FIB/SEM) images.ResultsIntact podocytes consisted of four subcellular compartments: cell body, primary process, ridge-like prominence (RLP), and foot process. The RLP, a longitudinal protrusion from the basal surface of the cell body and primary process, served as an adhesive apparatus for the cell body and primary process to attach to the glomerular basement membrane. Foot processes protruded from both sides of the RLP. In puromycin nephrotic podocytes, foot process effacement occurred in two ways: by type-1 retraction, where the foot processes retracted while maintaining their rounded tips; or type-2 retraction, where they narrowed across their entire lengths, tapering toward the tips. Puromycin nephrotic podocytes also exhibited several alterations associated with foot process effacement, such as deformation of the cell body, retraction of RLPs, and cytoplasmic fragmentation. Finally, podocytes were reorganized into a broad, flattened shape.ConclusionsThe three-dimensional reconstruction of podocytes by serial FIB/SEM images revealed the morphologic changes involved in foot process effacement in greater detail than previously described.

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28

Skalak, Richard, Cheng Dong, and Cheng Zhu. "Passive Deformations and Active Motions of Leukocytes." Journal of Biomechanical Engineering 112, no. 3 (August 1, 1990): 295–302. http://dx.doi.org/10.1115/1.2891187.

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The purpose of this paper is to review the development of continuum mechanics models of single leukocytes in both passive deformations and active motions and to indicate some future directions. Models of passive deformations describe the overall rheological behavior of single leukocytes under externally applied forces and predict the average mechanical properties from experimental data. Various “apparent” viscoelastic coefficients are obtained depending on the models assumed and the types of test used. Models of spontaneous motions postulate active driving mechanisms which must be derived internally from the cell itself and probably have different bases for different kind of motions. For pseudopod protrusion on leukocytes, energy transduction from chemical potential to mechanical work associated with actin polymerization at the tip of the projection is assumed to supply the motive power. For pseudopod retraction, active contraction due to actin-myosin interaction is assumed to be the driving force. The feasibility of the hypotheses are tested via numerical examples and comparison of the theoretical results with experimental measurements.

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29

Toki, Shigeyuki, Benjamin S. Hsiao, Shinzo Kohjiya, Masatoshi Tosaka, Andy H. Tsou, and Sudhin Datta. "Synchrotron X-Ray Studies of Vulcanized Rubbers and Thermoplastic Elastomers." Rubber Chemistry and Technology 79, no. 3 (July 1, 2006): 460–88. http://dx.doi.org/10.5254/1.3547946.

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Abstract Synchrotron X-ray diffraction technique has revealed strain-induced crystallization and molecular orientation in vulcanized rubbers and thermoplastic elastomers (TPE) during deformation in real time. The stress-strain curves and wide angle X-ray diffraction (WAXD) patterns in vulcanized rubbers and TPE were measured simultaneously. In-situ WAXD patterns were taken not only at different strains during uniaxial deformation but also at different temperatures at a constant strain. Results lead to several new insights. (i) Strain-induced crystallization is a common phenomenon in vulcanized rubbers, except SBR (styrene-butadiene rubber), and in TPE (with crystalline hard segments). (ii) Strain-induced crystallization decreases the stress and increases the elongation in the strained rubber. (iii) The hybrid structure of chemical networks and strain-induced crystallites is responsible to the tensile strength and elongation at break for both systems. (iiii) Some original crystal fraction (hard segment domain) in TPE is destroyed. During deformation, strain-induced crystallization increases with strain. Upon retraction even to stress zero, the majority of oriented strain-induced crystallites remains in tack with preferred orientation.

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Kokorkin, D. M., V. V. Skorobogaty, O. O. Gusakova, P. P. Shevlyuk, and N. A. Kolyada. "From secretory otitis to retraction cholesteatoma." Modern medical technology, no. 3(50) (September 20, 2021): 31–34. http://dx.doi.org/10.34287/mmt.3(50).2021.6.

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Based on the preliminary examination and further treatment of 980 children, the most influential consequences of secretory otitis were identified and the means of their prevention were proposed. Based on the results of long-term observation, conclusions were drawn. Chronic secretory otitis develops in 16% of children with recurrent secretory otitis, in 25% of cases the disease becomes malignant, and in 10% of cases goes into the stage of chronic purulent otitis media. In the treatment of recurrent and complicated chronic secretory otitis, it is advisable to follow the sequence of treatment, because 68% of children show existing or hidden signs of sinusitis, which requires prior surgical treatment. Among the detected forms, polyposis sinusitis with deformation of the nasal septum predominates (88,5%). The presence of retraction cholesteatoma with a predominant distribution within the tympanic cavity, limited defects of the chain of auditory ossicles and wide possibilities of their replacement, delayed cholesteatoma process with atrophy of matrix structures create conditions for organ-sparing surgery which corresponds to closed tympanoplasty. The morphological and functional effect of such operations can reach 91,5 ± 1,7% of cases in the group of children and adolescents and 88,2 ± 2,1% of observations in the group of adult patients, while the snail reserve decreased by 10,9 ± 3,3 dB in the group of children and 28,4 ± 3,3 dB in the group of adult patients.

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Santangelo, P. G., and C. M. Roland. "Chain Ends and the Mullins Effect in Rubber." Rubber Chemistry and Technology 65, no. 5 (November 1, 1992): 965–72. http://dx.doi.org/10.5254/1.3538654.

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Abstract It has been suggested that “Mullins softening”, which is the anomalously low stress found in crosslinked rubbers that have been subjected to a reversing deformation history, might be caused by retraction of the chain ends along their primitive paths. Using natural rubber networks made from precursors of varying molecular weight, and an end-linked polytetrahydrofuran rubber, the fraction of chain ends was varied. From stress-strain relationships measured on these rubbers, it is concluded that Mullins softening is unrelated to the presence of chain ends, or to polydispersity in the lengths of network strands.

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32

Sotomayor-González, Arturo. "Retraction. A look at Mayan artificial cranial deformation practices: morphological and cultural aspects." Neurosurgical Focus 45, no. 1 (July 2018): E17. http://dx.doi.org/10.3171/2018.5.focus10200r.

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33

Platenik, L. A., M. I. Miga, D. W. Roberts, K. E. Lunn, F. E. Kennedy, A. Hartov, and K. D. Paulsen. "In vivo quantification of retraction deformation modeling for updated image-guidance during neurosurgery." IEEE Transactions on Biomedical Engineering 49, no. 8 (August 2002): 823–35. http://dx.doi.org/10.1109/tbme.2002.800760.

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34

Lee, Heon Sang, and Morton M. Denn. "The deformation and retraction of thermotropic LCP droplets in a flexible polymer matrix." Journal of Non-Newtonian Fluid Mechanics 93, no. 2-3 (October 2000): 315–23. http://dx.doi.org/10.1016/s0377-0257(00)00118-x.

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35

Zhao, Xin, Bo Li, Lei Wang, and Arie Kaufman. "Retraction Note: Texture-guided volumetric deformation and visualization using 3D moving least squares." Visual Computer 30, no. 9 (July 3, 2014): 1073. http://dx.doi.org/10.1007/s00371-014-1002-x.

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36

Roland, C. M. "Network Recovery from Uniaxial Extension: I. Elastic Equilibrium." Rubber Chemistry and Technology 62, no. 5 (November 1, 1989): 863–79. http://dx.doi.org/10.5254/1.3536280.

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Abstract The elastic response of rubber has a direct and controllable dependence on structure. The behavior of the various networks described herein is seen to be consonant with the well-established roles of spatial fluctuations of crosslinks and the inhibition of this Brownian motion by steric and entanglement constraints from neighboring chains. Although elasticity also governs to a large extent the nonequilibrium mechanical response, interpretation of the latter in terms of network structure is obscured by viscoelasticity. The junctions of real networks, having some freedom to reconfigure themselves away from strictly affine displacement, exhibit lower equilibrium stresses than predicted by the statistical model for affine chains. To the extent that this overestimation of the model and the compressive component of the retraction response mimic the effect of departures from equilibrium, some conformance of network behavior during retraction to Equation (1) may be realized. It is such a fortuitous circumstance that likely underlies the various proposals commending such a relationship. A measure of junction density is generally not obtainable from deformation experiments in which dissipative processes are active.

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37

Yan, W., and K. Komvopoulos. "Three-Dimensional Molecular Dynamics Analysis of Atomic-Scale Indentation." Journal of Tribology 120, no. 2 (April 1, 1998): 385–92. http://dx.doi.org/10.1115/1.2834438.

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The complete atomic-scale indentation cycle is analyzed using molecular dynamics simulations. A hysteresis is observed in the instantaneous normal force versus surface separation distance curve obtained with an atom or a rigid tip indenting and, subsequently, retracting from a dynamic face-centered-cubic substrate consisting of argon or copper. The generation of irreversible deformation in a Lennard-Jones solid is revealed in light of simulation results for indentation by a single atom. The direction of irreversible deformation is shown to coincide with that of macroscopic plastic flow. The compressive yield strength decreases with increasing substrate temperature and decreasing indentation speed. The phenomena of tip wetting by substrate atoms and connective neck formation, elongation, and rupture at the tip/substrate interface are elucidated by simulation results for the unloading process. It is shown that energy dissipation decreases as the substrate temperature increases and the energy consumed by irreversible deformation is always greater than that due to heating.

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38

Tominaga, Jun-ya, Motohiro Tanaka, Yoshiyuki Koga, Carmen Gonzales, Masaru Kobayashi, and Noriaki Yoshida. "Optimal Loading Conditions for Controlled Movement of Anterior Teeth in Sliding Mechanics." Angle Orthodontist 79, no. 6 (November 1, 2009): 1102–7. http://dx.doi.org/10.2319/111608-587r.1.

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Abstract Objective: To determine optimal loading conditions such as height of retraction force on the power arm and its position on the archwire in sliding mechanics. Materials and Methods: A 3D finite element method (FEM) was used to simulate en masse anterior teeth retraction in sliding mechanics. The degree of labiolingual tipping of the maxillary central incisor was calculated when the retraction force was applied to different heights of a power arm set mesial or distal to the canine. Results: When the power arm was placed mesial to the canine, at the level of 0 mm (bracket slot level), uncontrolled lingual crown tipping of the incisor was observed and the anterior segment of the archwire was deformed downward. At a power arm height of 5.5 mm, bodily movement was produced and the archwire was less deformed. When the power arm height exceeded 5.5 mm, the anterior segment of the archwire was raised upward and lingual root tipping occurred. When the power arm was placed distal to the canine, lingual crown tipping was observed up to a level of 11.2 mm. Conclusions: Placement of the power arm of an archwire between the lateral incisor and canine enables orthodontists to maintain better control of the anterior teeth in sliding mechanics. Both the biomechanical principles associated with the tooth's center of resistance and the deformation of the archwire should be taken into consideration for predicting and planning orthodontic tooth movement.

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Bloemberg, Jette, Fabian Trauzettel, Bram Coolen, Dimitra Dodou, and Paul Breedveld. "Design and evaluation of an MRI-ready, self-propelled needle for prostate interventions." PLOS ONE 17, no. 9 (September 7, 2022): e0274063. http://dx.doi.org/10.1371/journal.pone.0274063.

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Prostate cancer diagnosis and focal laser ablation treatment both require the insertion of a needle for biopsy and optical fibre positioning. Needle insertion in soft tissues may cause tissue motion and deformation, which can, in turn, result in tissue damage and needle positioning errors. In this study, we present a prototype system making use of a wasp-inspired (bioinspired) self-propelled needle, which is able to move forward with zero external push force, thereby avoiding large tissue motion and deformation. Additionally, the actuation system solely consists of 3D printed parts and is therefore safe to use inside a magnetic resonance imaging (MRI) system. The needle consists of six parallel 0.25-mm diameter Nitinol rods driven by the actuation system. In the prototype, the self-propelled motion is achieved by advancing one needle segment while retracting the others. The advancing needle segment has to overcome a cutting and friction force while the retracting needle segments experience a friction force in the opposite direction. The needle self-propels through the tissue when the friction force of the five retracting needle segments overcomes the sum of the friction and cutting forces of the advancing needle segment. We tested the performance of the prototype in ex vivo human prostate tissue inside a preclinical MRI system in terms of the slip ratio of the needle with respect to the prostate tissue. The results showed that the needle was visible in MR images and that the needle was able to self-propel through the tissue with a slip ratio in the range of 0.78–0.95. The prototype is a step toward self-propelled needles for MRI-guided transperineal laser ablation as a method to treat prostate cancer.

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40

Simon, S. I., and G. W. Schmid-Scho¨nbein. "Kinematics of Cytoplasmic Deformation in Neutrophils During Active Motion." Journal of Biomechanical Engineering 112, no. 3 (August 1, 1990): 303–10. http://dx.doi.org/10.1115/1.2891188.

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A procedure is proposed to measure the cytoplasmic deformation in active motile neutrophils in the form of cytoplasmic strains and strain rates. Three neighboring microspheres in a local region of the cytoplasm serve as markers for local motion. Their positions are tracked by means of a high resolution light microscope and serve to compute nonlinear measures of strains and strain rates together with the principal strains and principal directions. Active neutrophils exhibit large cytoplasmic strains both during periodic pseudopod projections and during continuous locomotion in a polarized shape. The cytoplasmic motion is often synchronized with the whole cell deformation. The local cytoplasmic strains exceed the strains estimated for the whole cell and are not reversible except in some cases of single pseudopod projections. Large strains are observed both in attached and freely suspended cells. Strain rates are relatively constant but show an increase during the pseudopod retraction phase. Local cytoplasmic strains in neutrophils are inhomogeneous and reach large values during passage of the contraction rings. Neutrophils rendered passive by treatment with cytochalasin or EDTA show a random motion of microspheres with much smaller displacements. These observations suggest that the cytoplasm of active neutrophil exhibits large cytoplasmic strains and strain rates in the absence of an external stress resulting in a high degree of intracellular mixing. The proposed technique may be applied to a wide range of problems in cell biology.

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Liu, Chang, Naoya Morimoto, Lan Jiang, Sohei Kawahara, Takako Noritomi, Hideaki Yokoyama, Koichi Mayumi, and Kohzo Ito. "Tough hydrogels with rapid self-reinforcement." Science 372, no. 6546 (June 3, 2021): 1078–81. http://dx.doi.org/10.1126/science.aaz6694.

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Most tough hydrogels are reinforced by introducing sacrificial structures that can dissipate input energy. However, because the sacrificial damage cannot rapidly recover, the toughness of these gels drops substantially during consecutive cyclic loadings. We propose a damageless reinforcement strategy for hydrogels using strain-induced crystallization. For slide-ring gels in which polyethylene glycol chains are highly oriented and mutually exposed under large deformation, crystallinity forms and melts with elongation and retraction, resulting both in almost 100% rapid recovery of extension energy and excellent toughness of 6.6 to 22 megajoules per cubic meter, which is one order of magnitude larger than the toughness of covalently cross-linked homogeneous gels of polyethylene glycol.

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Drozdov, Aleksey D., Rasmus Klitkou, and Jesper de C.Christiansen. "Effect of crystalline structure on the mechanical response of polypropylene under cyclic deformation." Journal of Polymer Engineering 33, no. 2 (April 1, 2013): 181–90. http://dx.doi.org/10.1515/polyeng-2012-0127.

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Abstract To evaluate the influence of crystalline structure on the mechanical behavior of polypropylene (PP), uniaxial tensile cyclic tests with a mixed program (oscillations between fixed maximum strains and the zero minimum stress) were performed on isotactic PP (iPP) manufactured by the Ziegler-Natta catalysis method, metallocene catalyzed PP (mPP), and annealed mPP. Although the stress-strain diagrams of iPP and mPP under tension are quite similar, their responses under unloading differ markedly. The residual strain (measured as the strain under retraction down to the zero stress) of iPP strongly exceeds that of non-annealed mPP, and annealing of mPP increases this difference. To rationalize these findings, constitutive equations are developed in cyclic viscoelasticity and viscoplasticity of semicrystalline polymers, and adjustable parameters in the stress-strain relations are found by fitting the observations. The ability of the model to describe the observed phenomenon and to predict the mechanical response in multi-cycle tensile tests, with various deformation programs, is demonstrated by numerical simulation.

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43

Bemfica, Cainã, Edgar Mamiya, and Fábio Castro. "Retraction Note: Axial-torsional fatigue and cyclic deformation of 304L stainless steel at room temperature." MATEC Web of Conferences 300 (2019): 08011. http://dx.doi.org/10.1051/matecconf/201930008011.

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This paper has been formally retracted on ethical grounds because it is not an original article. Indeed, it has already been partially published in another journal. Request approved by the proceedings Editor and the Publisher on February 28, 2022.

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44

Jafarzadeh, Hossein, and Alireza Babaei. "Retraction Note: Accumulative Radial-Forward Extrusion (ARFE) processing as a novel severe plastic deformation technique." Journal of Mechanical Science and Technology 30, no. 8 (August 2016): 3887. http://dx.doi.org/10.1007/s12206-016-0754-9.

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45

Shono, Naoyuki, Taichi Kin, Seiji Nomura, Satoru Miyawaki, Toki Saito, Hideaki Imai, Hirofumi Nakatomi, Hiroshi Oyama, and Nobuhito Saito. "Microsurgery Simulator of Cerebral Aneurysm Clipping with Interactive Cerebral Deformation Featuring a Virtual Arachnoid." Operative Neurosurgery 14, no. 5 (August 1, 2017): 579–89. http://dx.doi.org/10.1093/ons/opx155.

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Abstract BACKGROUND A virtual reality simulator for aneurysmal clipping surgery is an attractive research target for neurosurgeons. Brain deformation is one of the most important functionalities necessary for an accurate clipping simulator and is vastly affected by the status of the supporting tissue, such as the arachnoid membrane. However, no virtual reality simulator implementing the supporting tissue of the brain has yet been developed. OBJECTIVE To develop a virtual reality clipping simulator possessing interactive brain deforming capability closely dependent on arachnoid dissection and apply it to clinical cases. METHODS Three-dimensional computer graphics models of cerebral tissue and surrounding structures were extracted from medical images. We developed a new method for modifiable cerebral tissue complex deformation by incorporating a nonmedical image-derived virtual arachnoid/trabecula in a process called multitissue integrated interactive deformation (MTIID). MTIID made it possible for cerebral tissue complexes to selectively deform at the site of dissection. Simulations for 8 cases of actual clipping surgery were performed before surgery and evaluated for their usefulness in surgical approach planning. RESULTS Preoperatively, each operative field was precisely reproduced and visualized with the virtual brain retraction defined by users. The clear visualization of the optimal approach to treating the aneurysm via an appropriate arachnoid incision was possible with MTIID. CONCLUSION A virtual clipping simulator mainly focusing on supporting tissues and less on physical properties seemed to be useful in the surgical simulation of cerebral aneurysm clipping. To our knowledge, this article is the first to report brain deformation based on supporting tissues.

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Huynh, Ngoc-Phat, Tuan-Em Le, and Koo-Hyun Chung. "In Situ Measurement of Elastic and Frictional Properties Using Atomic Force Microscopy." Microscopy and Microanalysis 27, no. 6 (September 28, 2021): 1488–97. http://dx.doi.org/10.1017/s143192762101285x.

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Atomic force microscopy (AFM) can determine mechanical properties, associated with surface topography and structure, of a material at the nanoscale. Force–indentation curves that depict the deformation of a target specimen as a function of an applied force are widely used to determine the elastic modulus of a material based on a contact model. However, a hysteresis may arise due to friction between the AFM tip and a specimen. Consequently, the normal force detected using a photodetector during extension and retraction could be underestimated and overestimated, respectively, and the extension/retraction data could result in a significant difference in the elastic modulus measurement result. In this study, elastic modulus and friction coefficient values were determined based on an in situ theoretical model that compensated for the effect of friction on force–indentation data. It validated the proposed model using three different polymer specimens and colloidal-tipped probes for the force–indentation curve and friction loop measurements. This research could contribute to the accurate measurement of mechanical properties using AFM by enhancing the interpretation of force–indentation curves with friction-induced hysteresis. Furthermore, the proposed approach may be useful for analyzing in situ relationships between mechanical and frictional properties from a fundamental tribological perspective.

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Polyakova, Marina, and Eduard Golubchik. "Methodology of Technological Adaptation Applied to Powder Rolling." Key Engineering Materials 779 (September 2018): 174–80. http://dx.doi.org/10.4028/www.scientific.net/kem.779.174.

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Powder rolling is used for manufacturing long-length strip. For obtaining the product with high green density it is necessary to ensure shear strain in the deformation zone. Based on the principles of technologic adaptation the dual roll closed caliber with adaptively changed rigidity was constructed. It consists of upper bandage with shoulder, bottom bandage with groove in which the set of three rings (two aside and one central) is located. The pass is arranged by aside rings and outside surface of the central ring forming closed caliber while interacting with the shoulder of the upper bandage. The caliber output is equal to zero and the broadening at rolling is fully excluded. Such construction of the tool makes it possible to achieve high level of hydrostatic stress of tensor simultaneously with intensification of shear strains resulting in practically nonporous rolled strip. Taking into consideration peculiarities of calibre rolling the new criterion was proposed. This criterion enables to characterize roll system for each material, incompact materials in particular, considering retraction ability, to assess and identify the final square of the rolled material at different caliber configuration. Dependence of maximum value of powdered rolled strip thickness on dual roll closed caliber retraction surface value at different rolled strip width is presented.

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Zhang, Zhongke, Yang Yu, Huaxia Zhao, and Xijing Wang. "Interface Behavior and Impact Properties of Dissimilar Al/Steel Keyhole-Free FSSW Joints." Metals 9, no. 6 (June 18, 2019): 691. http://dx.doi.org/10.3390/met9060691.

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This work systematically investigates the interface behavior and impact properties of the keyhole-free friction stir spot welding (FSSW) of a dissimilar metal AA6082-T4 Al alloy and DP600 galvanized steel. The keyhole is eliminated by pin retraction technology. The welding process is in accordance with the welding temperature curve and the maximum temperature of the periphery of the shoulder, measured at about 500 °C. The transition layers were formed at the interface, in which the Al, Fe, and Zn elements form an inhomogeneous diffusion. A cloud cluster-like mechanical mixing of the Al and steel components is formed in the stirring zone. The impact toughness of the specimen with a welding parameter of 1000 rpm is the best. To a certain extent, the factors affecting the impact energy are not the maximum impact load but the maximum impact deformation. The maximum impact deformation directly reflects the post-crack propagation energy, which significantly affects its impact toughness. In addition, the impact fracture showed a mixed ductile and brittle fracture mode with a brittle–ductile transition zone. Most of the impact energy was absorbed by the ductile fracture.

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Ramírez-Gutiérrez, Kelsey A., Alejandro Medina-Santiago, Alfonso Martínez-Cruz, Ignacio Algredo-Badillo, and Hayde Peregrina-Barreto. "Retraction notice to “Eggshell deformation detection applying computer vision” [Comp. Electron. Agric. 158 (2019) 133–139]." Computers and Electronics in Agriculture 162 (July 2019): 1049. http://dx.doi.org/10.1016/j.compag.2019.04.034.

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Zhao, Bo, Yuqin Wang, Yunsheng Wang, Qianqian Feng, Jia Li, and Xun Zhao. "Retraction Note to: Triggering mechanism and deformation characteristics of a reactivated ancient landslide, Sichuan Province, China." Landslides 16, no. 8 (May 31, 2019): 1621. http://dx.doi.org/10.1007/s10346-019-01201-y.

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