Bibliografias temáticas / Mechanical constraint

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Literatura científica selecionada sobre o tema "Mechanical constraint"

Autor: Grafiati

Publicado: 8 de fevereiro de 2025

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Artigos de revistas sobre o assunto "Mechanical constraint"

ANGELES, J., e SANGKOO LEE. "THE MODELLING OF HOLONOMIC MECHANICAL SYSTEMS USING A NATURAL ORTHOGONAL COMPLEMENT". Transactions of the Canadian Society for Mechanical Engineering 13, n.º 4 (dezembro de 1989): 81–89. http://dx.doi.org/10.1139/tcsme-1989-0014.

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A computationally efficient and systematic algorithm for the modelling of constrained mechanical systems is developed and implemented in this paper. With this algorithm, the governing equations of mechanical systems comprised of rigid bodies coupled by holonomic constraints are derived by means of an orthogonal complement of the matrix of the velocity-constraint equations. The procedure is applicable to all types of holonomic mechanical systems, and it can be extended to cases including simple nonholonomic constraints. Holonomic mechanical systems having a simple Kinematic-chain structure, such as single-loop linkages and serial-type robotic manipulators, are analysed regarding the derivation of the matrix of the constraint equations and its orthogonal complement, and the computation of the constraint forces.

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GRILLO, S., F. MACIEL e D. PÉREZ. "CLOSED-LOOP AND CONSTRAINED MECHANICAL SYSTEMS". International Journal of Geometric Methods in Modern Physics 07, n.º 05 (agosto de 2010): 857–86. http://dx.doi.org/10.1142/s0219887810004580.

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In this paper, we study the relationship between closed-loop mechanical systems (CLMS) and higher-order constrained systems (HOCS). We show that second-order constraints, i.e. constraints in acceleration, can be used to construct a CLMS, where the control law is given by the related constraint force. As an example we show that, by means of appropriate constraints of this kind, stabilization can be achieved for the inertia wheel pendulum. We also consider the inverse problem, that is to say: can every CLMS be constructed from a HOCS, i.e. can every control law be seen as the constraint force related to a given set of constraints? We answer this question affirmatively, reflecting a deep connection between feedback systems and systems with constraints. Also, we study when these constraints can be integrated to constraints in velocities. We prove that this is possible for CLMSs constructed by means of linear methods and also by some global ones, as the kinetic shaping method with symmetry.

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Adams, Jeffrey D., e Daniel E. Whitney. "Application of Screw Theory to Constraint Analysis of Mechanical Assemblies Joined by Features". Journal of Mechanical Design 123, n.º 1 (1 de agosto de 1999): 26–32. http://dx.doi.org/10.1115/1.1334858.

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Screw Theory is used to provide mathematical models of assembly features, allowing the determination of positioning constraints imposed on one part in an assembly by another part based on the geometry of the features that join them. Several feature types have been modeled, and it is easy to model new ones. A user of this theory is able to combine members of this set to join two parts and then determine whether or not the defined feature set over-, under-, or fully-constrains the location and orientation of the part. The ability to calculate the state of constraint of parts in an assembly is useful in supporting quantitative design of properly constrained assemblies in CAD systems. Locational over-constraint of parts can lead to assembleability problems or require deformation of parts in order to complete the assembly.

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Kim, S. S., e M. J. Vanderploeg. "QR Decomposition for State Space Representation of Constrained Mechanical Dynamic Systems". Journal of Mechanisms, Transmissions, and Automation in Design 108, n.º 2 (1 de junho de 1986): 183–88. http://dx.doi.org/10.1115/1.3260800.

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This paper presents a numerical solution method for dynamic analysis of constrained mechanical systems. This method reduces a coupled set of differential and algebraic equations to state space form. The reduction uses an independent set of velocities which lie on the tangent plane of the constraint surface. The tangent plane is defined by the nullspace of constraint Jacobian matrix. The nullspace basis is found using QR decomposition of the constraint Jacobian matrix. Because the nullspace basis is not unique, directional continuity of the nullspace is difficult to preserve each time the Jacobiar is decomposed. This paper presents an updating algorithm that is used instead oj repeated decomposition. This preserves directional continuity of the Jacobian matrix and increases efficiency. State equations are then derived in terms of independent accelerations and therefore can efficiently be integrated. Generalized velocities are integrated with constraints to obtain positions. This method has demonstrated minimal constraint violations and improved efficiency. Numerical examples with singular configurations and redundant constraints are presented to demonstrate the effectiveness of the method.

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Barhorst, A. A., e L. J. Everett. "Contact/Impact in Hybrid Parameter Multiple Body Mechanical Systems". Journal of Dynamic Systems, Measurement, and Control 117, n.º 4 (1 de dezembro de 1995): 559–69. http://dx.doi.org/10.1115/1.2801115.

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The multiple motion regime (free/constrained) dynamics of hybrid parameter multiple body (HPMB) systems is addressed. Impact response has characteristically been analyzed using impulse-momentum techniques. Unfortunately, the classical methods for modeling complex HPMB systems are energy based and have proven ineffectual at modeling impact. The problems are exacerbated by the problematic nature of time varying constraint conditions. This paper outlines the reformulation of a recently developed HPMB system modeling methodology into an impulse-momentum formulation, which systematically handles the constraints and impact. The starting point for this reformulation is a variational calculus based methodology. The variational roots of the methodology allows rigorous equation formulation which includes the complete nonlinear hybrid differential equations and boundary conditions. Because the methodology presented in this paper is formulated in the constraint-free subspace of the configuration space, both holonomic and nonholonomic constraints are automatically satisfied. As a result, the constraint-addition/deletion algorithms are not needed. Generalized forces of constraint can be directly calculated via the methodology, so the condition for switching from one motion regime to another is readily determined. The resulting equations provides a means to determine after impact velocities (and velocity fields for distributed bodies) which provide the after collision initial conditions. Finally the paper demonstrates, via example, how to apply the methodology to contact/impact in robotic manipulators and structural systems.

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Khusanov, Kahramanjon. "Selecting Control Parameters of Mechanical Systems with Servoconstraints". E3S Web of Conferences 264 (2021): 04085. http://dx.doi.org/10.1051/e3sconf/202126404085.

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The research results on the derivation of equations of motion (a mathematical model) of a mechanical system constrained by holonomic constraints of the first and second kind, which contains only tangential components of the constraint of the second kind, are presented in the article. These tangential components are taken as control parameters. Besides, the controllability of the plate, considered in the Appel problem, is investigated.

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Cyril, X., J. Angeles e A. Misra. "DYNAMICS OF FLEXIBLE MULTIBODY MECHANICAL SYSTEMS". Transactions of the Canadian Society for Mechanical Engineering 15, n.º 3 (setembro de 1991): 235–56. http://dx.doi.org/10.1139/tcsme-1991-0014.

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In this paper the formulation and simulation of the dynamical equations of multibody mechanical systems comprising of both rigid and flexible-links are accomplished in two steps: in the first step, each link is considered as an unconstrained body and hence, its Euler-Lagrange (EL) equations are derived disregarding the kinematic couplings; in the second step, the individual-link equations, along with the associated constraint forces, are assembled to obtain the constrained dynamical equations of the multibody system. These constraint forces are then efficiently eliminated by simple matrix multiplication of the said equations by the transpose of the natural orthogonal complement of kinematic velocity constraints to obtain the independent dynamical equations. The equations of motion are solved for the generalized accelerations using the Cholesky decomposition method and integrated using Gear’s method for stiff differential equations. Finally, the dynamical behaviour of the Shuttle Remote Manipulator when performing a typical manoeuvre is determined using the above approach.

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Zhang, Cheng-Yin, e Neng-Hui Zhang. "Mechanical Constraint Effect on DNA Persistence Length". Molecules 27, n.º 22 (11 de novembro de 2022): 7769. http://dx.doi.org/10.3390/molecules27227769.

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Persistence length is a significant criterion to characterize the semi-flexibility of DNA molecules. The mechanical constraints applied on DNA chains in new single-molecule experiments play a complex role in measuring DNA persistence length; however, there is a difficulty in quantitatively characterizing the mechanical constraint effects due to their complex interactions with electrostatic repulsions and thermal fluctuations. In this work, the classical buckling theory of Euler beam and Manning’s statistical theories of electrostatic force and thermal fluctuation force are combined for an isolated DNA fragment to formulate a quantitative model, which interprets the relationship between DNA persistence length and critical buckling length. Moreover, this relationship is further applied to identify the mechanical constraints in different DNA experiments by fitting the effective length factors of buckled fragments. Then, the mechanical constraint effects on DNA persistence lengths are explored. A good agreement among the results by theoretical models, previous experiments, and present molecular dynamics simulations demonstrates that the new superposition relationship including three constraint-dependent terms can effectively characterize changes in DNA persistence lengths with environmental conditions, and the strong constraint-environment coupling term dominates the significant changes of persistence lengths; via fitting effective length factors, the weakest mechanical constraints on DNAs in bulk experiments and stronger constraints on DNAs in single-molecule experiments are identified, respectively. Moreover, the consideration of DNA buckling provides a new perspective to examine the bendability of short-length DNA.

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Hasanoglu, Mehmet Sinan, e Melik Dolen. "Feasibility enhanced particle swarm optimization for constrained mechanical design problems". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232, n.º 2 (8 de dezembro de 2016): 381–400. http://dx.doi.org/10.1177/0954406216681593.

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Constrained optimization problems constitute an important fraction of optimization problems in the mechanical engineering domain. It is not uncommon for these problems to be highly-constrained where a specialized approach that aims to improve constraint satisfaction level of the whole population as well as finding the optimum is deemed useful especially when the objective functions are very costly. A new algorithm called Feasibility Enhanced Particle Swarm Optimization (FEPSO), which treats feasible and infeasible particles differently, is introduced. Infeasible particles in FEPSO do not need to evaluate objective functions and fly only based on social attraction depending on a single violated constraint, called the activated constraint, which is selected at each iteration based on constraint priorities and flight occurs only along dimensions of the search space to which the activated constraint is sensitive. To ensure progressive improvement of constraint satisfaction, particles are not allowed to violate a satisfied constraint in FEPSO. The highly-constrained four-stage gear train problem and its two variants introduced in this paper are used to assess the effectiveness of FEPSO. The results suggest that FEPSO is effective and consistent in obtaining feasible points, finding good solutions, and improving the constraint satisfaction level of the swarm as a whole.

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Phong, Dinh Van. "Successive algorithm for construction of equation of motion of constrained mechanical systems". Vietnam Journal of Mechanics 24, n.º 2 (30 de junho de 2002): 101–14. http://dx.doi.org/10.15625/0866-7136/24/2/6612.

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The article devotes to the construction of equations of motion of constrained mechanical systems. The constraint conditions are successively appended to the already defined systems. Therefore the algorithm is very flexible and allows studying the separate constraints more in detail. For illustration of consequent steps of the algorithm one simple example is shown.

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Teses / dissertações sobre o assunto "Mechanical constraint"

Miller, James Thomas Ph D. Massachusetts Institute of Technology. "Mechanical behavior of elastic rods under constraint". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/88280.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2014.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 213-223).
We present the results of an experimental investigation of the mechanics of thin elastic rods under a variety of loading conditions. Four scenarios are explored, with increasing complexity: i) the shape of a naturally curved rod suspended under self-weight, ii) the buckling and post-buckling behavior of a rod compressed inside a cylindrical constraint, iii) the mechanical instabilities arising when a rod is progressively injected into a horizontal cylinder, and iv) strategies for mitigation of these instabilities by dynamic excitation of the constraint. First, we consider the role of natural curvature in determining the shape of a hanging elastic rod suspended under its own weight. We categorize three distinct configurations: planar hooks, localized helices, and global helices. Experimental results are contrasted with simulations and theory and the phase diagram of the system is rationalized. Secondly, in what we call the classic case experiment, we study the buckling and post-buckling behavior of a rod compressed inside a cylindrical constraint. Under imposed displacement, the initially straight rod buckles into a sinusoidal mode and eventually undergoes a secondary instability into a helical configuration. The critical buckling loads are quantified and found to depend strongly on the aspect ratio of the rod to pipe diameter. Thirdly, we inject a thin elastic rod into a horizontal cylinder under imposed velocity in the real case experiment. Friction between the rod and constraining pipe causes an increasing axial load with continued injection. Consecutive buckling transitions lead to straight, sinusoidal, and helical configurations in a spatially heterogeneous distribution. We quantify critical lengths and loads for the onset of the helical instability. The geometric parameters of the system strongly affect the buckling and post-buckling behavior. Finally, we explore active strategies for delaying the onset of helical buckling in the real case. Distributed vertical vibration is applied to the cylindrical constraint, which destabilizes frictional contacts between the rod and pipe. Injection speed, peak acceleration of vibration, and vibration frequency are all found to affect the postponement of helical initiation. The process is rationalized and design
by James T. Miller.
Ph. D.

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Serrano, David. "Constraint management in conceptual design". Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14689.

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Hermus, James Russell. "Human physical interaction with a circular constraint". Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/118670.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 113-119).
Despite large feedback delays, and many degrees of freedom, humans are incredibly dexterous and excel at physical interaction with complex objects. In this work we developed an upper limb crank turning experiment to study the human controller used to manage physical interaction. Subjects turned a crank with and without visual feedback, in two directions (clockwise and counterclockwise), and in three speed conditions (slow (0.075 rev/s), medium (0.5 rev/s), and fast (2 rev/s)). We made several predictions about the dependent measures including: mean speed, standard deviation of speed, coefficient of variation of speed, mean normal force, and standard deviation of normal force. We hypothesized that subjects should perform the best at slow speeds where the effect of feedback delays, inertial dynamics, and muscle noise decrease. Notably, subjects became more variable at slow speeds, and exerted significant nonzero normal force in the slow condition. At slow speeds, increased speed variability and compressive normal forces cannot be explained by biomechanics - suggesting they result from neural control. Next, the zero-force trajectory was computed. The zero-force trajectory allows for the peripheral biomechanics to be 'subtracted' to 'reveal' the underlying neural commands, expressed in terms of motion. We detected a coincidence of curvature and velocity extrema in the zero-force trajectory. Furthermore, this observation was robust to changes in impedance parameters. This finding is exciting. Even though the hand was confined to a circular path, when the peripheral biomechanics were subtracted, the same velocity curvature relationship seen in unconstrained movements was revealed. Lastly, the increased variability at slow speeds was present in the zero force trajectory. This indicates that the increased variability at slow speeds is a result of neural control, not biomechanics; this finding is consistent with previous research in unconstrained motion.
National Science Foundation National Robotics Initiative Grant No. 1637824
by James Russell Hermus.
S.M.

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Karstensen, Annette Degn. "Constraint estimation schemes in fracture mechanics". Thesis, University of Glasgow, 1996. http://theses.gla.ac.uk/7228/.

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Elastic-plastic crack tip constraint has been estimated for the common planar crack geometries. These include single edge cracked bars in tension and bending, centre cracked panels, and double edge cracked bars. The description of the stress field has been modified from a one parameter characterisation, based on K or J, to include a second term. The second parameter is a non-singular term, described either in terms of an elastic T-stress or a Q field. The limits of one and two parameter characterisation are discussed for single edge bars in tension and bending and for centre cracked panels. For the single edge geometries the two parameter characterisation was found to extend the characterisation well beyond the one parameter approach. For the centre cracked panels the two parameter characterisation in terms of a J-Q approach was found to be more accurate than a J-T approach at high levels of deformation. For the single edge cracked bending and tension geometries the second parameter Q is divided into two components named QT and QP. QT is an elastic term which depends on the elastic T stress and is independent of the distance from the crack tip. The second component, QP, arises from global bending on the uncracked ligament. This is a distance dependent term which depends on the level of deformation and can either be expressed as a function of the load normalised by the limit load or as a function of the plastic component of the J-integral. For single edge bend bars the constraint estimation provides a basis for a method of predicting fracture toughness using local failure approach, where the failure criterion is expressed in terms of the stress level ahead of the crack tip. Finally the constraint of mixed mode problem has been analysed and compared with that of pure Mode I problems.

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Agrawal, Rajiv. "A Constraint Management Approach for Optimal Design of Mechanical Systems". Connect to resource, 1991. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1225216291.

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Forest, Craig Richard 1978. "X-ray telescope foil optics : assembly, metrology, and constraint". Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/89385.

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Dias, Carlson Rachel (Rachel A. ). "Precision constraint of deformable bodies for medical imaging applications". Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/103465.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 102-104).
The purpose of this work is to learn how the performance of a constraint system that interfaces with nonlinear elastic materials such as biological tissue can be predicted by a model. The direct application of this work is the determination of the feasibility of restraining awake and anesthetized mice skulls to submicron levels of movement for biological imaging applications without direct attachment to the skull. A device capable of restricting mouse skull movement to less than a micron in every direction without requiring the rigid attachment of a fixture to the skull would enable studies of bone marrow activity that are not currently possible. No existing work has attempted to determine the performance limits of a constraint system interfacing with nonlinear elastic material. This thesis introduces a model for determining the constraint system performance, and demonstrates how material properties may be tested to determine their relative significance and inclusion in the system model. The theoretical model is applied to the case of an awake mouse to demonstrate that a tissue-interfacing constraint system can only limit movement to hundreds of microns and is not capable of achieving the desired submicron level performance. For the case of an anesthetized mouse, the designed device is tested and achieves the desired sub-micron performance in all three axes for improved imaging capabilities in anesthetized mice.
by Rachel Dias Carlson.
S.M.

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Anderson, Sterling J. Ph D. Massachusetts Institute of Technology. "Constraint-based navigation for safe, shared control of ground vehicles". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/79314.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 138-147).
Human error in machine operation is common and costly. This thesis introduces, develops, and experimentally demonstrates a new paradigm for shared-adaptive control of human-machine systems that mitigates the effects of human error without removing humans from the control loop. Motivated by observed human proclivity toward navigation in fields of safe travel rather than along specific trajectories, the planning and control framework developed in this thesis is rooted in the design and enforcement of constraints rather than the more traditional use of reference paths. Two constraint-planning methods are introduced. The first uses a constrained Delaunay triangulation of the environment to identify, cumulatively evaluate, and succinctly circumscribe the paths belonging to a particular homotopy with a set of semi autonomously enforceable constraints on the vehicle's position. The second identifies a desired homotopy by planning - and then laterally expanding - the optimal path that traverses it. Simulated results show both of these constraint-planning methods capable of improving the performance of one or multiple agents traversing an environment with obstacles. A method for predicting the threat posed to the vehicle given the current driver action, present state of the environment, and modeled vehicle dynamics is also presented. This threat assessment method, and the shared control approach it facilitates, are shown in simulation to prevent constraint violation or vehicular loss of control with minimal control intervention. Visual and haptic driver feedback mechanisms facilitated by this constraint-based control and threat-based intervention are also introduced. Finally, a large-scale, repeated measures study is presented to evaluate this control framework's effect on the performance, confidence, and cognitive workload of 20 drivers teleoperating an unmanned ground vehicle through an outdoor obstacle course. In 1,200 trials, the constraint-based framework developed in this thesis is shown to increase vehicle velocity by 26% while reducing the occurrence of collisions by 78%, improving driver reaction time to a secondary task by 8.7%, and increasing overall user confidence and sense of control by 44% and 12%, respectively. These performance improvements were realized with the autonomous controller usurping less than 43% of available vehicle control authority, on average.
by Sterling J. Anderson.
Ph.D.

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Mulcahy, Connor Gordon. "Rotation of a slender rod injected into a cylindrical constraint". Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/103460.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 59-61).
We investigate the buckling of a slender elastic rod injected into a cylindrical constraint while undergoing axial rotation. Particular focus is given to extension of the helical buckling length. This problem is of particular application to coiled tubing operations in the oil and gas industry where helical buckling and eventual lockup occur, thereby preventing complete access to horizontal oil wells. Our approach focuses on using desktop experiments to perform a precise exploration of the parameters affecting buckling. We examine two separate modes of axial rotation: continuous rotation and oscillatory rotation. In each case, we demonstrate potential for significant increases in helical buckling length by a factor of as much as 5 within the parameter space studied and develop an understanding of the underlying mechanisms at play. In the case of continuous rotation, we compare our experimental results to theoretical predictions motivated by this work. The extensions in helical buckling length observed here suggest significant application to the problem of helical buckling in coiled tubing operations.
by Connor Gordon Mulcahy.
S.M.

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Rusli, Leonard Priyatna. "Design and analysis of mechanical assembly via kinematic screw theory". Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1218042368.

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Livros sobre o assunto "Mechanical constraint"

M, Hackett E., Schwalbe K. -H e Dodds R. H. 1955-, eds. Constraint effects in fracture. Philadelphia, PA: ASTM, 1993.

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Gajewski, Antoni. Optimal structural design under stability constraints. Dordrecht: Kluwer Academic Publishers, 1988.

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Joyce, J. A. Effects of tensile loading on upper shelf fracture toughness. Washington, DC: Division of Engineering, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, 1994.

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Hermann, Robert. Constrained mechanics and Lie theory. Brookline, Mass: Math Sci Press, 1992.

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1961-, Kirk Mark, e Bakker Ad 1946-, eds. Constraint effects in fracture theory and applications: Second volume. Philadelphia, PA, U.S.A: ASTM, 1995.

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Gajewski, Antoni. Optimal Structural Design under Stability Constraints. Dordrecht: Springer Netherlands, 1988.

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Leine, Remco I., e Nathan van de Wouw, eds. Stability and Convergence of Mechanical Systems with Unilateral Constraints. Berlin, Heidelberg: Springer Berlin Heidelberg, 2008. http://dx.doi.org/10.1007/978-3-540-76975-0.

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de, Wouw Nathan van, ed. Stability and convergence of mechanical systems with unilateral constraints. Berlin: Springer, 2008.

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F, Shih C., Anderson T. L. 1957-, U.S. Nuclear Regulatory Commission. Office of Nuclear Regulatory Research. Division of Engineering., University of Illinois at Urbana-Champaign. Dept. of Civil Engineering., Brown University. Division of Engineering., Texas A & M University. Dept. of Mechanical Engineering. e Naval Surface Warfare Center (U.S.). Annapolis Detachment., eds. Continuum and micromechanics treatment of constraint in fracture. Washington, DC: Division of Engineering, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, 1993.

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U.S. Nuclear Regulatory Commission. Office of Nuclear Regulatory Research. Division of Engineering Technology., Valtion teknillinen tutkimuskeskus, University of Illinois at Urbana-Champaign. Dept. of Civil Engineering. e Naval Surface Warfare Center (U.S.), eds. Numerical investigation of 3-D contraint effects on brittle fracture in SE(B) and C(T) specimens. Washington, DC: Division of Engineering Technology, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, 1996.

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Capítulos de livros sobre o assunto "Mechanical constraint"

García de Jalón, Javier, e Eduardo Bayo. "Dependent Coordinates and Related Constraint Equations". In Mechanical Engineering Series, 16–70. New York, NY: Springer New York, 1994. http://dx.doi.org/10.1007/978-1-4612-2600-0_2.

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Bolshakov, R. S., I. S. Sitov e S. V. Eliseev. "Unilateral Constraints in Interactions of System Elements: Estimation of Dynamic Constraint Reactions". In Lecture Notes in Mechanical Engineering, 851–60. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-54814-8_98.

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Pluvinage, Guy, Julien Capelle e Mohamed Hadj Meliani. "Transferability of Fracture Toughness with Constraint". In Lecture Notes in Mechanical Engineering, 87–99. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-41468-3_7.

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Guo, Zijun, Huilong Yu e Junqiang Xi. "Time-Optimal Learning-Based LTV-MPC for Autonomous Racing". In Lecture Notes in Mechanical Engineering, 228–34. Cham: Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-70392-8_33.

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AbstractAutonomous racing is a time- and accuracy-critical application of vehicle motion planning and control techniques. Despite being promising for its ability to handle constraints, model predictive control (MPC) for autonomous racing is limited by the relatively low computational speed and the problem of model mismatch. In this work, we present a time-optimal linear-time-variant-MPC (LTV-MPC) that incorporates a min-time objective function, the friction ellipse constraint, and the successive linearization over the prediction horizon to improve computational speed and prediction accuracy. To tackle model mismatch, the proposed LTV-MPC is further combined with Gaussian process regression to learn the lateral tire force error. Compensation for the error is implemented over the prediction horizon and on the friction ellipse constraint. This work presents simulation validation on the racing track of Formula Student Autonomous China (FSAC) and experimental validation on a self-designed track. We show that compared with nonlinear MPC, the proposed LTV-MPC reduces the average computation time from 66 ms to 2.5 ms with a 0.6% increase in lap time. With learned tire force error, a 2% reduction in lap time can be achieved.

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Russell, D. M., e K. D. Willmert. "Elimination of Constraint Equations from Flexible Mechanical Systems". In Computational Dynamics in Multibody Systems, 99–118. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-017-1110-4_7.

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Chlup, Z., e I. Dlouhý. "Micromechanical Aspects of Constraint Effect at Brittle Fracture Initiation". In Transferability of Fracture Mechanical Characteristics, 65–78. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0608-8_5.

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Triki, Hager, e Zainab Tkitek. "Manual Assembly Line Balancing Problem with Constraint COVID 19: (SALBCOVID19P)". In Lecture Notes in Mechanical Engineering, 37–44. Cham: Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-57324-8_5.

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Datt, Mohit, Ajay Gupta e Sushendra Kumar Misra. "Identification of Constraint in Healthcare Unit by Using Dice Game". In Lecture Notes in Mechanical Engineering, 47–57. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-7445-0_5.

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Jiang, Zhongyu, Yajun Zhang, Huaqing Liu e Xuanxuan Li. "Symplectic Elastic Solution of Multi-layer Thick-Walled Cylinder Under Different Interlayer Constraints". In Lecture Notes in Civil Engineering, 238–53. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-1260-3_21.

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AbstractMulti-layer thick-walled cylinder is a common supporting structure in engineering, which is widely used in various engineering fields. Considering the complex boundary conditions and the different interlayer constraints, it is difficult to solve the theoretical solution of multi-layer thick walled cylinder. In this paper, the general solution expressions of displacement and stress of multi-layer thick-walled cylinder are derived in Hamiltonian mechanics system. The complex boundary conditions are transformed into the form of algebraic sum by Fourier series expansion, and the complex boundary problems are solved by superimposing the special solutions of each order expansion term. At the same time, according to the characteristics of different interlayer constraints, the corresponding conditions of interlayer continuous smooth are proposed. Combined with the boundary conditions of thick-walled cylinder, the linear equations with undetermined coefficients are established. By solving the equations, the mechanical problems of multi-layer thick-walled cylinder are finally solved. By comparing the mechanical responses of multi-layer thick-walled cylinder under different constraint conditions, it is concluded that the overall mechanical performance of the tight interlayer connection is better, and the circumfluence stress component is more prominent than other stress components. Finally, the influence of lateral pressure coefficient and elastic modulus ratio on the circumferential stress of multi-layer thick-walled cylinder is discussed. These research results provide the necessary theoretical basis for solving the mechanical problems of multi-layer thick-walled cylinders.

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Hager, Triki, e Hassine Hichem. "A PSO Approach for Job Shop Scheduling Problem with Energy Constraint". In Lecture Notes in Mechanical Engineering, 761–68. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-14615-2_85.

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Trabalhos de conferências sobre o assunto "Mechanical constraint"

Wei, Cui, Ye-Hwa Chen e Yanling Wei. "Constraint-Following Based Adaptive Robust Control for Underactuated Mechanical Systems". In 2024 18th International Conference on Control, Automation, Robotics and Vision (ICARCV), 314–19. IEEE, 2024. https://doi.org/10.1109/icarcv63323.2024.10821703.

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Liu, Jiemin, e T. Sawa. "Three-Level Optimization Design of Laminated Composite Structures and Design Variable Chain". In ASME 1997 International Mechanical Engineering Congress and Exposition, 1–6. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-1338.

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Abstract A three-level optimization design method suitable for laminated composite structures subjected to complex external loads under constraint conditions, such as strength, displacement, twist, and size constraints, is presented. In order to reduce the scale of optimization still further, the design variable chain (DVC) is applied to the optimal design of laminated composite structures. The numerical examples show that: (1) the three-level optimization method is effective for solving the the optimum design problems of laminated composite structures which are subjected to behavior and size constraints under complicated external loads; (2) the use of DVC can reduce the time of optimization process greatly.

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Wu, J. K., J. H. Wang, C. X. Feng e T. H. Liu. "A Logic-Based Mechanical System Constraint Model". In ASME 1993 International Computers in Engineering Conference and Exposition. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/edm1993-0115.

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Abstract This paper presents some initial developments in modeling design constraints of mechanical systems using predicate logic. This design constraint modeling method is to manage design changes in a concurrent engineering environment that has CAE and CAM applications. The design constraints are classified according to an object hierarchy of a mechanical system information model which has five levels object including: a mechanical system level, assembly level, and part level. The constraint relationships are defined and formally expressed using predicate logic. Feature fitting and against relationships between parts in the assembly level and relationships between features of a part in the part level have been illustrated in the paper.

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Franciosa, P., e S. Gerbino. "A CAD-Based Methodology for Motion and Constraint Analysis According to Screw Theory". In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-13159.

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The need for a designer to have a tool able to do motion and constraint analysis, to check for the under-constrained and/or over-constrained status of an assembly, is strategic in a design contest where several changes are made during the design process by using CAD. Traditional kinematic tools provide little information on over-constraints at 3D level. Screw theory has been already used in mechanical assemblies, in a top-down design, to do motion and constraint analysis. This theory is here used to analyze mechanical assemblies in the contest of a feature-based CAD system. The structure of the CAD assembly is captured and described as assembly graph, similar to Datum Flow Chain, through which the motion or constraint status of any part (in terms of twist and wrench matrices), can be obtained. The underlying algorithm is based on the Kirchoff’s rules successfully applied by Davies to mechanisms. How to automatically create the assembly graph, detect the useful loops and then write the loop kinematic equations is described. Three case studies are presented related to CAD assemblies of mechanisms built up in SolidWorks® CAD system by Dassault Systemes from which assembly constraints have been acquired.

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Fernando, Terrence, Prasad Wimalaratne, Kevin Tan e Norman Murray. "Interactive Product Simulation Environment for Assessing Assembly and Maintainability Tasks". In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0173.

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Abstract This paper presents the design and implementation of an interactive product simulation environment for supporting interactive assembly and maintenance tasks. The system architecture of the constraint-based virtual environment is based on the integration of components such as OpenGL Optimizer, Parasolid geometric kernel, a Constraint Engine, an Assembly Relationship Graph (ARG) and a task model. The approach presented in this paper is based on pure geometric constraints. Techniques such as automatic constraint recognition, constraint satisfaction, constraint management and constrained motion are employed to support interactive assembly operations and realistic behaviour of assembly parts. The user inputs are handled using a task model based on Augmented Transition Networks (ATN). The current system has been evaluated using two industrial case studies.

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Wang, J. Y., e J. K. Wu. "Singularity of Constraint Mechanical Systems". In ASME 1993 Design Technical Conferences. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/detc1993-0286.

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Abstract The solution set of nonlinear kinematic constraint equations can be divided into regular and critical solution subsets, according to linear dependency of gradient vectors of the constraint equations. However, relative to a given input coordinate set, the solution set can also be separated into singular and nonsingular solution subsets, according to whether the sub-Jacobian matrix with respect to the output and intermediate coordinates is rank deficient or not. By providing precise definitions and classifications of singular configurations, from both mathematical and physical points of view, a better understanding of the kinematic behavior of singularity is obtained. Moreover, by extending the definition of the singular solution set to the output space and exploring the mathematical meaning of it, the difficulty in formulating mathematical expressions for workspace problems is resolved.

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Rooney, Francis J., e Stephen E. Bechtel. "Modeling of Thermal Expansion". In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0937.

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Abstract In this paper we treat two types of thermomechanical constraints, temperature-deformation and entropy-deformation. It is shown that for the temperature-deformation constraint equilibrium states are unstable, in that certain perturbations of the equilibrium state grow exponentially. The entropy-deformation constraint, however, does not exhibit this instability. By considering the constrained materials as limits of unconstrained materials, it is shown that the instability is associated with the loss of convexity of the internal energy.

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Anderson, D. D., J. H. Jackson, J. S. Epstein, S. Ganti e D. M. Parks. "Constraint Fracture in Simulated Weldments". In ASME 1996 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/imece1996-0633.

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Abstract Simulated under-matched butt weldments have been fabricated using commercially pure titanium (CP Ti) as an interleaf material diffusion bonded to a higher strength 6Al-4V titanium (6Al-4V Ti). Four-point bend bars were constructed where-by the only changing geometric feature is the thickness of the CP Ti interleaf which varied from 12 to 1.7 mm. The CP Ti and 6Al-4V Ti elastic moduli are 112.3 and 115.1 MPa while the yield stresses are 366 MPa and 896 MPa respectively. A through-crack was inserted in the center of the CP Ti interleaf. Due to the close moduli, the elastic T constraint terms do not change as the CP Ti interleaf thickness is varied. However, under plastic loading, the thickness of the interleaf has a large effect on the local plastic fields surrounding the crack tip as well as the initiation J values. Using a hybrid approach with moire interferometry and finite element methods, it has been found that the higher strength 6Al-4V Ti acts to constrain the crack tip plastic zone. The net result of this constraint is a reorientation of plastic flow in the CP Ti interleaf from 90 to 45 and 135 degrees and a mean stress 2.8 times larger that the flow stress. To understand the effect of the hydrostatic constraint on the initiation process in the CP Ti interleaf, a series of double interleaf tensile bars have been developed to obtain stress-strain curves of the CP Ti interleaf under varied constraint states. These tensile specimens indicate that for the highly constrained CP Ti interleafs, that the mode of fracture initiation is due to a form of cleavage initiating at the titanium carbide stringers.

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Wang, J. H., e J. K. Wu. "An Assembly Constraint Model for Parameterized Mechanical Systems". In ASME 1994 International Computers in Engineering Conference and Exhibition and the ASME 1994 8th Annual Database Symposium collocated with the ASME 1994 Design Technical Conferences. American Society of Mechanical Engineers, 1994. http://dx.doi.org/10.1115/edm1994-0500.

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Abstract This paper (1) introduces Natural Assembly Relationships (NARs) to model assembly constraints between parts and (2) analyzes the constraint relationships that are defined using NARs for parameterized mechanical assemblies. The NARs are expressed as first order predicates using primitive features as arguments, such as planar and cylindrical surfaces. The concept of Basic Parameters Set is introduced as the design parameters in CAD systems, which, together with a set of form feature constraint relationships, maintains maximal consistency with original design meanings. Based on NARs, part parameters, and primitive features, design parameter chains can be constructed for closed loop assemblies. From these chains, constraint equations can be derived, which are the basis for change propagation and information management for mechanical system design.

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Klisch, Stephen M. "A Mixture of Elastic Materials With Internal Constraints". In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0936.

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Abstract A treatment of internally constrained mixtures of elastic materials at a common temperature is developed. Internal constraints involving the deformation gradient tensors and the common mixture temperature are represented by a constraint manifold, and an internally constrained mixture of elastic materials is associated with each unique equivalence class of unconstrained mixtures. Several examples are discussed.

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Relatórios de organizações sobre o assunto "Mechanical constraint"

Park. L52339 Small Scale Low Constraint Fracture Toughness Test Results for High Strength Pipelines. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), dezembro de 2011. http://dx.doi.org/10.55274/r0010460.

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This is the fifth report of a series of seven reports detailing the small-scale mechanical testing performed on the trial welds in this consolidated program. An outline of the reporting flow is given in the Introduction to the Summary of Mechanical Properties report 277-T-08. The present report contains the results of application of the low-constraint tensile toughness test, supplemented with results of shallow-notch bend tests, to the three series of welds in the consolidated program, including tests on base metal, weld metal, and HAZ.

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Tyson. L52337 Weld Design Testing and Assessment Procedures for High Strength Pipelines. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), dezembro de 2011. http://dx.doi.org/10.55274/r0010448.

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This is the last report of a�c reports detailing the small-scale mechanical testing performed on the trial welds in this consolidated program. This report summarizes and compares the results of all of the mechanical tests applied primarily to welds of rounds 1 and 2, including tensile results and their correlation with microstructure, Charpy test results, conventional (through-thickness-notched) toughness tests, and low-constraint toughness tests. The reports contains a summary of the mechanical properties of the experimental single and dual torch GMAW-P X100 pipe welds prepared for this consolidated program. It summarizes the detailed results reported in Final Reports 277-T-05, 277-T-06 and 277-T-07. The intent of this summary is to provide insight and understanding of the significance of the results and the implications for mechanical testing of weldments to extract properties essential for strain-based design (SBD).

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Tyson. L52341 Summary of Publications-Single-Edge Tension SE(T) Tests. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), dezembro de 2011. http://dx.doi.org/10.55274/r0010462.

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A low-constraint test designed to reduce unnecessary conservatism in the measurement of toughness for use in the assessment of flaws in pipeline girth welds has been developed. The test was first proven on nominally homogeneous material (pipe base metal) to check the practicality of the procedures and to study the effects of the controlling geometric parameters (a/W, etc.) on toughness. The intent of this report is to reference the publications resulting from this work and to summarize the principal conclusions. This is the third report of a series of seven technical reports detailing the small-scale mechanical testing performed on the trial welds in this consolidated program. An outline of the reporting flow is given in the Introduction to the Summary of Mechanical Properties technical report 277-T-08. The present report highlights the principal results of preliminary application of the toughness test procedure that have been published in a series of papers in the open literature.

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Wijaya, Ignasius P. A., Eric Kreiger e Asuf Masud. An elastic-inelastic model and embedded bounce-back control for layered printing with cementitious materials. Engineer Research and Development Center (U.S.), janeiro de 2024. http://dx.doi.org/10.21079/11681/48091.

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This paper presents a finite-deformation model for extrusion-based layered printing with cementitious materials. The evolution of mechanical properties as the printed material cures and stiffens results in nonphysical reduction in the magnitude of elastic strains when standard constitutive models are employed. This elastic recovery of the printing induced deformation contradicts the experimentally observed behavior of the printed cementitious materials that harden at a nearly-frozen deformed state. A thermodynamically motivated constraint on the evolution of elastic strains is imposed on the constitutive model to remedy the nonphysical bounce-back effect. An algorithm that is based on a strain-projection technique for the elastic part of deformation is developed that complements the inelastic response given by the Drucker–Prager model. It is then embedded in a finite strain finite element framework for the modeling and simulation of cure hardening and inelastic response of the early age cementitious materials. A ghost mesh method is proposed for continuous layer-wise printing of the material without the need for intermittent mesh generation technique or adaptive remeshing methods. The model is validated via comparison with experimental data and representative test cases are presented that investigate the mathematical and computational attributes of the proposed model.

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Dmitry Karpeyev, Derek Gaston, Jason Hales e Steven Novascone. Mechanical contact by constraints and split-based preconditioning. Office of Scientific and Technical Information (OSTI), março de 2014. http://dx.doi.org/10.2172/1134842.

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Gee, Michael W., e Raymond Stephen Tuminaro. Nonlinear algebraic multigrid for constrained solid mechanics problems using Trilinos. Office of Scientific and Technical Information (OSTI), abril de 2006. http://dx.doi.org/10.2172/883128.

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Christie, Benjamin, Jordan Klein, Anton Netchaev e Garry Glaspell. Integrating MOVEit motion constraints on a novel robotic manipulator. Engineer Research and Development Center (U.S.), novembro de 2023. http://dx.doi.org/10.21079/11681/47845.

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MOVEit, a widely used Robot Operating System framework, plans composite tasks, where the high-level sequence of actions is fixed and known in advance. However, these tasks need to be tailored and adapted to the environmental context. This framework uses custom trajectory planners, known as controllers, to solve goals that are fully defined within the configuration space. Libraries, such as the Open Motion Planning Library, provide a collection of motion planners that can solve task-space goals. An exact spatial and joint replication of the robotic manipulator’s mechanics, typically Universal Robot Description Format and Semantic Robot Description Format files, is required. Common arms such as the Panda-Manipulator and OpenMANIPULATOR-X provide these files in their respective public repositories, but custom arms require significant modification or even a complete rewrite of these files.

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Baker, Michael. DTRS56-02-D-70036-16 Mechanical Damage. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), abril de 2009. http://dx.doi.org/10.55274/r0011844.

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This report reviews and summarizes the current state of knowledge and practice related to mechanical damage in natural gas and hazardous liquid steel pipelines, with a particular focus on transmission pipelines. Comprehensive voluntary interviews were conducted with 10 pipeline operators who represent a diverse cross-section of industry professionals in the United States, Canada, and Europe. The interviews, which focused on operator practices for detection, characterization, and mitigation of mechanical damage on both gas and liquid transmission and gas distribution pipelines (the latter examined for comparison purposes), provided an invaluable source of data for the development of this report. Operator practices associated with the prevention of mechanical damage primarily resulting from excavation damage were also extensively covered in the interviews. The inquiry primarily included pipelines that comprise transmission systems, but gas distribution companies also reported on their experience with distribution systems consisting of both steel and plastic pipe, the latter reviewed for a comprehensive discussion of the operator's damage prevention programs and issues. Pipeline geographic locations included remote and rugged terrain, rural areas, and constrained urban environments.

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Mohamed, W. Out-of-Pile Task 14.5.1: Impact of Mechanical Constraints on Peak Cladding Strain of U-10Mo Monolithic Plate. GTRI - Reactor Conversion Program, Out-of-Pile Testing and Codes, Task 14.5.1. Office of Scientific and Technical Information (OSTI), outubro de 2014. http://dx.doi.org/10.2172/1159037.

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Engel, Bernard, Yael Edan, James Simon, Hanoch Pasternak e Shimon Edelman. Neural Networks for Quality Sorting of Agricultural Produce. United States Department of Agriculture, julho de 1996. http://dx.doi.org/10.32747/1996.7613033.bard.

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The objectives of this project were to develop procedures and models, based on neural networks, for quality sorting of agricultural produce. Two research teams, one in Purdue University and the other in Israel, coordinated their research efforts on different aspects of each objective utilizing both melons and tomatoes as case studies. At Purdue: An expert system was developed to measure variances in human grading. Data were acquired from eight sensors: vision, two firmness sensors (destructive and nondestructive), chlorophyll from fluorescence, color sensor, electronic sniffer for odor detection, refractometer and a scale (mass). Data were analyzed and provided input for five classification models. Chlorophyll from fluorescence was found to give the best estimation for ripeness stage while the combination of machine vision and firmness from impact performed best for quality sorting. A new algorithm was developed to estimate and minimize training size for supervised classification. A new criteria was established to choose a training set such that a recurrent auto-associative memory neural network is stabilized. Moreover, this method provides for rapid and accurate updating of the classifier over growing seasons, production environments and cultivars. Different classification approaches (parametric and non-parametric) for grading were examined. Statistical methods were found to be as accurate as neural networks in grading. Classification models by voting did not enhance the classification significantly. A hybrid model that incorporated heuristic rules and either a numerical classifier or neural network was found to be superior in classification accuracy with half the required processing of solely the numerical classifier or neural network. In Israel: A multi-sensing approach utilizing non-destructive sensors was developed. Shape, color, stem identification, surface defects and bruises were measured using a color image processing system. Flavor parameters (sugar, acidity, volatiles) and ripeness were measured using a near-infrared system and an electronic sniffer. Mechanical properties were measured using three sensors: drop impact, resonance frequency and cyclic deformation. Classification algorithms for quality sorting of fruit based on multi-sensory data were developed and implemented. The algorithms included a dynamic artificial neural network, a back propagation neural network and multiple linear regression. Results indicated that classification based on multiple sensors may be applied in real-time sorting and can improve overall classification. Advanced image processing algorithms were developed for shape determination, bruise and stem identification and general color and color homogeneity. An unsupervised method was developed to extract necessary vision features. The primary advantage of the algorithms developed is their ability to learn to determine the visual quality of almost any fruit or vegetable with no need for specific modification and no a-priori knowledge. Moreover, since there is no assumption as to the type of blemish to be characterized, the algorithm is capable of distinguishing between stems and bruises. This enables sorting of fruit without knowing the fruits' orientation. A new algorithm for on-line clustering of data was developed. The algorithm's adaptability is designed to overcome some of the difficulties encountered when incrementally clustering sparse data and preserves information even with memory constraints. Large quantities of data (many images) of high dimensionality (due to multiple sensors) and new information arriving incrementally (a function of the temporal dynamics of any natural process) can now be processed. Furhermore, since the learning is done on-line, it can be implemented in real-time. The methodology developed was tested to determine external quality of tomatoes based on visual information. An improved model for color sorting which is stable and does not require recalibration for each season was developed for color determination. Excellent classification results were obtained for both color and firmness classification. Results indicted that maturity classification can be obtained using a drop-impact and a vision sensor in order to predict the storability and marketing of harvested fruits. In conclusion: We have been able to define quantitatively the critical parameters in the quality sorting and grading of both fresh market cantaloupes and tomatoes. We have been able to accomplish this using nondestructive measurements and in a manner consistent with expert human grading and in accordance with market acceptance. This research constructed and used large databases of both commodities, for comparative evaluation and optimization of expert system, statistical and/or neural network models. The models developed in this research were successfully tested, and should be applicable to a wide range of other fruits and vegetables. These findings are valuable for the development of on-line grading and sorting of agricultural produce through the incorporation of multiple measurement inputs that rapidly define quality in an automated manner, and in a manner consistent with the human graders and inspectors.

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