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Journal articles on the topic 'Explicit constraints'

Author: Grafiati

Published: 4 June 2021

Last updated: 16 February 2022

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1

Udwadia, F. E., and R. E. Kalaba. "Explicit Equations of Motion for Mechanical Systems With Nonideal Constraints." Journal of Applied Mechanics 68, no. 3 (October 9, 2000): 462–67. http://dx.doi.org/10.1115/1.1364492.

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Since its inception about 200 years ago, Lagrangian mechanics has been based upon the Principle of D’Alembert. There are, however, many physical situations where this confining principle is not suitable, and the constraint forces do work. To date, such situations are excluded from general Lagrangian formulations. This paper releases Lagrangian mechanics from this confinement, by generalizing D’Alembert’s principle, and presents the explicit equations of motion for constrained mechanical systems in which the constraints are nonideal. These equations lead to a simple and new fundamental view of Lagrangian mechanics. They provide a geometrical understanding of constrained motion, and they highlight the simplicity with which Nature seems to operate.

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Udwadia, Firdaus E., and Phailaung Phohomsiri. "Explicit Poincaré equations of motion for general constrained systems. Part I. Analytical results." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 463, no. 2082 (March 6, 2007): 1421–34. http://dx.doi.org/10.1098/rspa.2007.1825.

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This paper gives the general constrained Poincaré equations of motion for mechanical systems subjected to holonomic and/or nonholonomic constraints that may or may not satisfy d'Alembert's principle at each instant of time. It also extends Gauss's principle of least constraint to include quasi-accelerations when the constraints are ideal, thereby expanding the compass of this principle considerably. The new equations provide deeper insights into the dynamics of multi-body systems and point to new ways for controlling them.

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Eun, Hee-Chang, Eun-Taik Lee, and Heon-Soo Chung. "On the static analysis of constrained structural systems." Canadian Journal of Civil Engineering 31, no. 6 (December 1, 2004): 1119–22. http://dx.doi.org/10.1139/l04-036.

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Complete structures might contain so many degrees of freedom that it would be infeasible to perform a structural analysis. The derivation of the equilibrium equations of an entire structure to utilize kinematical compatibility conditions at the interfaces of the substructures requires complicated intermediate processes or numerical schemes for determining multipliers. This study derives an explicit matrix form of the equilibrium equations of structural systems subjected to constraints like compatibility conditions or linear displacement relations. The equation is obtained by minimizing a quadratic form of the variation in unconstrained and constrained displacements with respect to all constrained displacements that satisfy the constraints. And the physical meaning of the constraint forces required to satisfy the constraints is investigated. The validity of the proposed method is illustrated by several applications.Key words: constraints, compatibility, equilibrium equation, generalized inverse.

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Yang, Xiaohui, Xiaolong Zhang, Shaoping Xu, Yihui Ding, Kun Zhu, and Xiaoping Liu. "An Approach to the Dynamics and Control of Uncertain Robot Manipulators." Algorithms 12, no. 3 (March 26, 2019): 66. http://dx.doi.org/10.3390/a12030066.

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In this paper, a novel constraint-following control for uncertain robot manipulators that is inspired by analytical dynamics is developed. The motion can be regarded as external constraints of the system. However, it is not easy to obtain explicit equations for dynamic modeling of constrained systems. For a multibody system subject to motion constraints, it is a common practice to introduce Lagrange multipliers, but using these to obtain explicit dynamical equations is a very difficult task. In order to obtain such equations more simply, motion constraints are handled here using the Udwadia-Kalaba equation(UKE). Then, considering real-life robot manipulators are usually uncertain(but bounded), by using continuous controllers compensate for the uncertainties. No linearizations/approximations of the robot manipulators systems are made throughout, and the tracking errors are bounds. A redundant manipulator of the SCARA type as the example to illustrates the methodology. Numerical results are demonstrates the simplicity and ease of implementation of the methodology.

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PYATOV, P. N., and A. V. RAZUMOV. "GAUGE INVARIANCE AND CONSTRAINTS." International Journal of Modern Physics A 04, no. 13 (August 10, 1989): 3211–28. http://dx.doi.org/10.1142/s0217751x8900131x.

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It is shown that in the Hamiltonian description of a wide class of gauge invariant Lagrangian systems there arise only primary and secondary constraints and they are all first class. The explicit expressions for the Poisson brackets of the Hamiltonian and the constraints are obtained by introducing the so-called “standard” extension of functions originally defined on the primary constraint surface to the whole phase space.

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6

van Oosterom, A., and G. J. M. Huiskamp. "Implicit and explicit constraints in inverse electrocardiography." Journal of Electrocardiology 25 (January 1992): 87–92. http://dx.doi.org/10.1016/0022-0736(92)90067-a.

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7

Fonseca, Daniel Guerra Vale da, André Felipe O. de A. Dantas, Carlos Eduardo Trabuco Dórea, and André Laurindo Maitelli. "Explicit GPC Control Applied to an Approximated Linearized Crane System." Journal of Control Science and Engineering 2019 (February 3, 2019): 1–13. http://dx.doi.org/10.1155/2019/3612634.

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This paper proposes a MIMO Explicit Generalized Predictive Control (EGPC) for minimizing payload oscillation of a Gantry Crane System subject to input and output constraints. In order to control the crane system efficiently, the traditional GPC formulation, based on online Quadratic Programming (QP), is rewritten as a multiparametric quadratic programming problem (mp-QP). An explicit Piecewise Affine (PWA) control law is obtained and holds the same performance as online QP. To test effectiveness, the proposed method is compared with two GPC formulations: one that handle constraints (CGPC) and another that does not handle constraints (UGPC). Results show that both EGPC and CGPC have better performance, reducing the payload swing when compared to UGPC. Also both EGPC and CGPC are able to control the system without constraint violation. When comparing EGPC to CGPC, the first is able to calculate (during time step) the control action faster than the second. The simulations prove that the overall performance of EGPC is superior to the other used formulations.

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8

Udwadia, F. E., and R. E. Kalaba. "What is the General Form of the Explicit Equations of Motion for Constrained Mechanical Systems?" Journal of Applied Mechanics 69, no. 3 (May 1, 2002): 335–39. http://dx.doi.org/10.1115/1.1459071.

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This paper presents the general form of the explicit equations of motion for mechanical systems. The systems may have holonomic and/or nonholonomic constraints, and the constraint forces may or may not satisfy D’Alembert’s principle at each instant of time. The explicit equations lead to new fundamental principles of analytical mechanics.

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9

Qiu, Qiang, and Qixin Cao. "Task constrained motion planning for 7-degree of freedom manipulators with parameterized submanifolds." Industrial Robot: An International Journal 45, no. 3 (May 21, 2018): 363–70. http://dx.doi.org/10.1108/ir-01-2018-0004.

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PurposeThis paper aims to use the redundancy of a 7-DOF (degree of freedom) serial manipulator to solve motion planning problems along a given 6D Cartesian tool path, in the presence of geometric constraints, namely, obstacles and joint limits.Design/methodology/approachThis paper describes an explicit expression of the task submanifolds for a 7-DOF redundant robot, and the submanifolds can be parameterized by two parameters with this explicit expression. Therefore, the global search method can find the feasible path on this parameterized graph.FindingsThe proposed planning algorithm is resolution complete and resolution optimal for 7-DOF manipulators, and the planned path can satisfy task constraint as well as avoiding singularity and collision. The experiments on Motoman SDA robot are reported to show the effectiveness.Research limitations/implicationsThis algorithm is still time-consuming, and it can be improved by applying parallel collision detection method or lazy collision detection, adopting new constraints and implementing more effective graph search algorithms.Originality/valueCompared with other task constrained planning methods, the proposed algorithm archives better performance. This method finds the explicit expression of the two-dimensional task sub-manifolds, so it’s resolution complete and resolution optimal.

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10

SERRANO, ALEJANDRO, and JURRIAAN HAGE. "Constraint handling rules with binders, patterns and generic quantification." Theory and Practice of Logic Programming 17, no. 5-6 (August 22, 2017): 992–1009. http://dx.doi.org/10.1017/s1471068417000230.

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AbstractConstraint handling rules provide descriptions for constraint solvers. However, they fall short when those constraints specify some binding structure, like higher-rank types in a constraint-based type inference algorithm. In this paper, the term syntax of constraints is replaced by λ-tree syntax, in which binding is explicit, and a new ∇ generic quantifier is introduced, which is used to create new fresh constants.

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11

Repnikov, Vasily I., Boris V. Faleichik, and Andrew V. Moisa. "Stabilised explicit Adams-type methods." Journal of the Belarusian State University. Mathematics and Informatics, no. 2 (August 5, 2021): 82–98. http://dx.doi.org/10.33581/2520-6508-2021-2-82-98.

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In this work we present explicit Adams-type multi-step methods with extended stability intervals, which are analogous to the stabilised Chebyshev Runge – Kutta methods. It is proved that for any k ≥ 1 there exists an explicit k-step Adams-type method of order one with stability interval of length 2k. The first order methods have remarkably simple expressions for their coefficients and error constant. A damped modification of these methods is derived. In the general case, to construct a k-step method of order p it is necessary to solve a constrained optimisation problem in which the objective function and p constraints are second degree polynomials in k variables. We calculate higher-order methods up to order six numerically and perform some numerical experiments to confirm the accuracy and stability of the methods.

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12

Chen, Hu, Yi Xia Zhang, Meng Yan Zang, and Paul Jonathan Hazell. "An Explicit Lagrange Constraint Method for Finite Element Analysis of Frictionless 3D Contact/Impact Problems." Applied Mechanics and Materials 553 (May 2014): 751–56. http://dx.doi.org/10.4028/www.scientific.net/amm.553.751.

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An effective contact algorithm is essential for modeling complicated contact/impact problems. Unlike the penalty method, the Lagrange multiplier method can generate more precise results while not adversely affecting stability; however, its formulation in explicit contact treatment is singular. In order to overcome this deficiency, a new Lagrange constraint method with different constraints under initial impact and persistent contact is proposed. In this method, the coupled contact system equilibrium equations with non-diagonal coefficient matrix are uncoupled via Gauss-seidel iteration strategy. Particularly, this implicit contact treatment can be compatible with explicit time integration scheme. To reduce oscillations, the displacement constraint is imposed under initial impact, while the combined constraints of velocity, acceleration and displacement are enforced under persistent contact. Numerical example validates this method.

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13

Srivatsan, R., D. A. Hoeltzel, and A. Das. "An Analytical Method for the Identification of Redundant Constraints in Multiple-Loop Spatial Mechanisms." Journal of Mechanical Design 115, no. 2 (June 1, 1993): 324–31. http://dx.doi.org/10.1115/1.2919195.

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An analytical method for the explicit identification of redundant constraints in multiple-loop spatial mechanisms is presented. The kinematic constraint equations for each independent loop of multiple-loop mechanisms are developed. The independence of these equations is established and used to detect the presence of redundant constraints. The nature of the redundant constraints present is indicated by the type of redundant kinematic constraint equations present. Interaction of the constraints of adjacent loops in a multiple-loop mechanism also has to be taken into account. An example which illustrates the identification of redundant constraints in a cardan joint has been included to demonstrate the utility of this approach for real-world mechanism design problems. General guidelines for the elimination of redundant constraints, following their identification, are also provided.

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14

Pompe, Waldemar. "Explicit Construction of Piecewise Affine Mappings with Constraints." Bulletin of the Polish Academy of Sciences Mathematics 58, no. 3 (2010): 209–20. http://dx.doi.org/10.4064/ba58-3-4.

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15

Foster, David L., and Darrin M. Hanna. "Applying partial fault tolerance with explicit area constraints." International Journal of Embedded Systems 5, no. 1/2 (2013): 67. http://dx.doi.org/10.1504/ijes.2013.052145.

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16

Oikonomou, Kostas N., and Peter D. Grunwald. "Explicit Bounds for Entropy Concentration Under Linear Constraints." IEEE Transactions on Information Theory 62, no. 3 (March 2016): 1206–30. http://dx.doi.org/10.1109/tit.2015.2458951.

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17

Curran, Joanne M. "Constraints of Pretend Play: Explicit and Implicit Rules." Journal of Research in Childhood Education 14, no. 1 (December 1999): 47–55. http://dx.doi.org/10.1080/02568549909594751.

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18

Pérez, Emilio, Carlos Ariño, F. Xavier Blasco, and Miguel A. Martínez. "Explicit predictive control with non-convex polyhedral constraints." Automatica 48, no. 2 (February 2012): 419–24. http://dx.doi.org/10.1016/j.automatica.2011.07.011.

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19

Filipiuk, Piotr, Hanne Riis Nielson, and Flemming Nielson. "Explicit Versus Symbolic Algorithms for Solving ALFP Constraints." Electronic Notes in Theoretical Computer Science 267, no. 2 (October 2010): 15–28. http://dx.doi.org/10.1016/j.entcs.2010.09.015.

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20

Vladimirsky, V. V. "Explicit solutions of constraints in the Virasoro algebra." Physics Letters B 267, no. 1 (September 1991): 59–62. http://dx.doi.org/10.1016/0370-2693(91)90524-t.

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21

SEMIKHATOV, A. M. "CONTINUUM REDUCTION OF VIRASORO-CONSTRAINED LATTICE HIERARCHIES." Modern Physics Letters A 06, no. 28 (September 14, 1991): 2601–12. http://dx.doi.org/10.1142/s0217732391003043.

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Integrable hierarchies with Virasoro constraints have been observed to describe matrix models. I suggest to define general Virasoro-constrained integrable hierarchies by imposing Virasora-highest-weight conditions on the dressing operators. This simplifies the study of the Virasoro constraints and allows an explicit construction of a scaling which implements the continuum limit of discrete (lattice) hierarchies. Applied to the Toda lattice hierarchy subjected to the Virasoro constraints, this scaling leads to the Virasoro-constrained KP hierarchy. Therefore, in particular, the KP hierarchy is shown to arise as the scaling limit of a matrix model.

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22

FISCH, JEAN M. L. "SECOND CLASS CONSTRAINTS IN THE BATALIN-VILKOVISKY LAGRANGIAN BRST QUANTIZATION." Modern Physics Letters A 05, no. 03 (January 30, 1990): 195–205. http://dx.doi.org/10.1142/s021773239000024x.

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The antibracket-antifield BRST formalism developed by Batalin and Vilkovisky is applied to constrained Hamiltonian systems with second class constraints. We derive an effective path integral in which first class and second class constraints are incorporated in a BRST invariant gauge fixed action. Full explicit agreement is found with the canonical path integral quantization of systems with second class constraints and, consequently, with the Lagrangian and Hamiltonian BRST quantization of first order Hamiltonian systems where the second class constraints have been eliminated by introducing the Dirac bracket.

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23

Sahu, Chinmay, V. Kirubakaran, TK Radhakrishnan, and N. Sivakumaran. "Explicit model predictive control of split-type air conditioning system." Transactions of the Institute of Measurement and Control 39, no. 5 (December 16, 2015): 754–62. http://dx.doi.org/10.1177/0142331215619976.

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Domestic air conditioners are a major source of energy consumption. In this study, utilizing real-time data from a public domain, a cascaded hardware in loop approach to the control of room temperature is considered. An inner loop to control the supply air temperature by adjusting the electronic expansion valve using a second-order plus delay time model is proposed. The room temperature control is considered the outer loop. A simplified lumped parameter representation of the thermal dynamics of the building is modelled in MATLAB using ordinary differential equations. A constrained multi parametric model predictive controller (mpMPC) is designed for both the control loops. The constraints include safety limits on the superheat and manipulation rates for the inner loop and a rate constraint on the reference signal in the outer loop. Model uncertainties like ambient temperature and thermal load variations (representing an office space) are considered for hardware in the loop testing of the proposed strategy. From performance analysis, using power spent and thermal comfort quantization, it is observed that the mpMPC scheme outperforms traditional control strategies.

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24

Boonen, Tim J., and Mario Ghossoub. "BILATERAL RISK SHARING WITH HETEROGENEOUS BELIEFS AND EXPOSURE CONSTRAINTS." ASTIN Bulletin 50, no. 1 (January 2020): 293–323. http://dx.doi.org/10.1017/asb.2019.39.

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AbstractThis paper studies bilateral risk sharing under no aggregate uncertainty, where one agent has Expected-Utility preferences and the other agent has Rank-dependent utility preferences with a general probability distortion function. We impose exogenous constraints on the risk exposure for both agents, and we allow for any type or level of belief heterogeneity. We show that Pareto-optimal risk-sharing contracts can be obtained via a constrained utility maximization under a participation constraint of the other agent. This allows us to give an explicit characterization of optimal risk-sharing contracts. In particular, we show that an optimal risk-sharing contract contains allocations that are monotone functions of the likelihood ratio, where the latter is obtained from Lebesgue’s Decomposition Theorem.

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25

HO, R. J., S. A. MEGUID, and R. G. SAUVÉ. "NOVEL COUPLING CONSTRAINT TECHNIQUE FOR EXPLICIT FINITE ELEMENT ANALYSIS." International Journal of Computational Methods 01, no. 02 (September 2004): 309–28. http://dx.doi.org/10.1142/s0219876204000150.

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This paper presents a unified novel technique for enforcing nonlinear beam-to-shell, beam-to-solid, and shell-to-solid constraints in explicit finite element formulations. The limitations of classical multi-point constraint approaches are examined at length, particularly in the context of explicit solution schemes. Novel formulation of a generalized constraint method that ensures proper element coupling is then presented, and its computer implementation in explicit integration algorithms is discussed. Crucial in this regard is the accurate and efficient representation of finite rotations, accomplished using an incremental rotation tensor. The results of some illustrative test cases show the accuracy and robustness of the newly developed algorithm for a wide range of deformation, including that in which large rotations are encountered. When compared to existing works, the salient features of the current method are in evidence.

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26

Ahmad, Sanwar Uddin, M. Babul Hasan, and M. Ainul Islam. "Algorithm to Perform a Complete RHS Parametric Analysis for LPP with Bounded Variables." Dhaka University Journal of Science 60, no. 2 (August 3, 2012): 217–22. http://dx.doi.org/10.3329/dujs.v60i2.11521.

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Linear Programming problem (LPP)s with upper bounded variables can be solved using the Bounded Simplex method, without the explicit consideration of the upper bounded constraints. One can consider the upper bounded constraints explicitly and perform the regular righthand- side parametric analysis of LPPs with bounded variables. This paper develops a method to perform the parametric analysis where the upper bounded constraints are considered implicitly, thus reduce the size of the basis matrix.DOI: http://dx.doi.org/10.3329/dujs.v60i2.11521 Dhaka Univ. J. Sci. 60(2): 217-222, 2012 (July)

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27

YO, HWEI-JANG, and JAMES M. NESTER. "HAMILTONIAN ANALYSIS OF POINCARÉ GAUGE THEORY SCALAR MODES." International Journal of Modern Physics D 08, no. 04 (August 1999): 459–79. http://dx.doi.org/10.1142/s021827189900033x.

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The Hamiltonian constraint formalism is used to obtain the first explicit complete analysis of nontrivial viable dynamic modes for the Poincaré gauge theory of gravity. Two modes with propagating spin-zero torsion are analyzed. The explicit form of the Hamiltonian is presented. All constraints are obtained and classified. The Lagrange multipliers are derived. It is shown that a massive spin -0- mode has normal dynamical propagation but the associated massless 0- is pure gauge. The spin -0+ mode investigated here is also viable in general. Both modes exhibit a simple type of "constraint bifurcation" for certain special field/parameter values.

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28

Li, Chenming, Han Zhao, Shengchao Zhen, Kang Huang, Hao Sun, Ke Shao, and Bin Deng. "Trajectory Tracking Control of Parallel Manipulator Based on Udwadia-Kalaba Approach." Mathematical Problems in Engineering 2017 (December 14, 2017): 1–12. http://dx.doi.org/10.1155/2017/8975743.

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There have been many approaches for achieving the trajectory tracking control of parallel manipulator. However, these approaches are complex for calculating Lagrangian multipliers. In this paper, unlike the former approaches, a new approach of trajectory tracking control which is based on Udwadia-Kalaba approach is presented. Using this methodology, we can obtain a concise and explicit equation of motion and consider holonomic and nonholonomic constraint whether it is ideal or nonideal simultaneously. The most important difference is that we divide constraints into structural constraints and performance constraints in this paper. Structural constraints are used to establish dynamic model without regard for trajectory control. And performance constraints are used to represent the desired trajectory. For the parallel manipulator, a nonlinear dynamics system, its constraint forces are obtained by second-order constraints. And the numerical simulation in MATLAB shows the parallel manipulator’s movement meets the requirement; tracking trajectory is exact and perfect. Through this paper, we can see that the method can simplify calculation availably.

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29

Hobbs, N. Thompson, and David M. Swift. "Estimates of Habitat Carrying Capacity Incorporating Explicit Nutritional Constraints." Journal of Wildlife Management 49, no. 3 (July 1985): 814. http://dx.doi.org/10.2307/3801716.

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30

Lee, S. K., D. Su, V. Coussot, and D. Griffith. "Explicit routing with QoS constraints in IP over WDM." IEE Proceedings - Communications 149, no. 2 (April 1, 2002): 83–91. http://dx.doi.org/10.1049/ip-com:20020033.

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31

Baknina, Abdulrahman, Omur Ozel, and Sennur Ulukus. "Energy Harvesting Communications Under Explicit and Implicit Temperature Constraints." IEEE Transactions on Wireless Communications 17, no. 10 (October 2018): 6680–92. http://dx.doi.org/10.1109/twc.2018.2861874.

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BATALIN, I. A., I. V. TYUTIN, and S. L. LYAKHOVICH. "SPLIT INVOLUTION COUPLED TO ACTUAL GAUGE SYMMETRY." International Journal of Modern Physics A 10, no. 13 (May 20, 1995): 1917–36. http://dx.doi.org/10.1142/s0217751x95000930.

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The split involution quantization scheme, proposed previously for pure second class constraints only, is extended to cover the case of the presence of irreducible first class constraints. The explicit Sp (2) symmetry property of the formalism is retained. The constraint-algebra-generating equations are formulated and the unitarizing Hamiltonian is constructed. Physical operators and states are defined in the sense of the new equivalence criterion which is a natural counterpart of Dirac’s weak equality concept as applied to the first class quantities.

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33

Shi, Heng, Yanbing Liang, and Zhaohui Liu. "An approach to the dynamic modeling and sliding mode control of the constrained robot." Advances in Mechanical Engineering 9, no. 2 (February 2017): 168781401769047. http://dx.doi.org/10.1177/1687814017690470.

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An approach to the dynamic modeling and sliding mode control of the constrained robot is proposed in this article. On the basis of the Udwadia–Kalaba approach, the explicit equation of the constrained robot system is obtained first. This equation is applicable to systems with either holonomic or non-holonomic constraints, as well as with either ideal or non-ideal constraint forces. Second, fully considering the uncertainty of the non-ideal force, that is, the dynamic friction in the constrained robot system, the sliding mode control algorithm is put forward to trajectory tracking of the end-effector on a vertical constrained surface to obtain actual values of the unknown constraint force. Moreover, model order reduction method is innovatively used in the Udwadia–Kalaba approach and sliding mode controller to reduce variables and simplify the complexity of the calculation. Based on the demonstration of this novel method, a detailed robot system example is finally presented.

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Hall, Alison. "‘Free’ Enrichment and the Nature of Pragmatic Constraints." International Review of Pragmatics 6, no. 1 (2014): 1–28. http://dx.doi.org/10.1163/18773109-00601002.

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The contextualist approach to utterance interpretation posits processes of “free” pragmatic enrichment that supply unarticulated constituents of the explicit content of utterances. While this proposal is faithful to our intuitions about the truth conditions of utterances, and accommodates the optionality of these pragmatic effects, there remains a doubt about whether contextualism can account in any principled way for what pragmatically derived material enters into explicit content, and what does not. This gap in the theory leads to objections that the putative process of pragmatic enrichment would massively overgenerate interpretations of utterances, having no way to exclude from explicit content elements of meaning that are truth-conditionally irrelevant. Here I discuss how a derivational account can sort explicit content from implicatures, where the former is a result of “developing” the linguistically-encoded form, while implicatures are entirely inferred, from fully propositional premises. Using the idea that enrichment is constrained to the minimum necessary to inferentially warrant the implications of the utterance, I show how the derivational account can address existing examples of alleged overgeneration, and that these rest on a failure to properly appreciate that the occurrence of such “free” pragmatic processes depends on the details of the particular context in which the utterance was tokened. I conclude with a discussion of what kind of systematicity should be expected from an account of processes whose outcome is inevitably context-specific.

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Stellan, Ohlsson, and Antonija Mitrovic. "Constraint-based knowledge representation for individualized instruction." Computer Science and Information Systems 3, no. 1 (2006): 1–22. http://dx.doi.org/10.2298/csis0601001s.

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Traditional knowledge representations were developed to encode complete explicit and executable programs, a goal that makes them less than ideal for representing the incomplete and partial knowledge of a student. In this paper, we discuss state constraints, a type of knowledge unit originally invented to explain how people can detect and correct their own errors. Constraint-based student modeling has been implemented in several intelligent tutoring systems (ITS) so far, and the empirical data verifies that students learn while interacting with these systems. Furthermore, learning curves are smooth when plotted in terms of individual constraints, supporting the psychological appropriateness of the representation. We discuss the differences between constraints and other representational formats, the advantages of constraint-based models and the types of domains in which they are likely to be useful.

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Liu, Zhe, and Albert C. Reynolds. "A Sequential-Quadratic-Programming-Filter Algorithm with a Modified Stochastic Gradient for Robust Life-Cycle Optimization Problems with Nonlinear State Constraints." SPE Journal 25, no. 04 (April 8, 2020): 1938–63. http://dx.doi.org/10.2118/193925-pa.

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Summary Solving a large-scale optimization problem with nonlinear state constraints is challenging when adjoint gradients are not available for computing the derivatives needed in the basic optimization algorithm used. Here, we present a methodology for the solution of an optimization problem with nonlinear and linear constraints, where the true gradients that cannot be computed analytically are approximated by ensemble-based stochastic gradients using an improved stochastic simplex approximate gradient (StoSAG). Our discussion is focused on the application of our procedure to waterflooding optimization where the optimization variables are the well controls and the cost function is the life-cycle net present value (NPV) of production. The optimization algorithm used for solving the constrained-optimization problem is sequential quadratic programming (SQP) with constraints enforced using the filter method. We introduce modifications to StoSAG that improve its fidelity [i.e., the improvements give a more accurate approximation to the true gradient (assumed here to equal the gradient computed with the adjoint method) than the approximation obtained using the original StoSAG algorithm]. The modifications to StoSAG vastly improve the performance of the optimization algorithm; in fact, we show that if the basic StoSAG is applied without the improvements, then the SQP might yield a highly suboptimal result for optimization problems with nonlinear state constraints. For robust optimization, each constraint should be satisfied for every reservoir model, which is highly computationally intensive. However, the computationally viable alternative of letting the reservoir simulation enforce the nonlinear state constraints using its internal heuristics yields significantly inferior results. Thus, we develop an alternative procedure for handling nonlinear state constraints, which avoids explicit enforcement of nonlinear constraints for each reservoir model yet yields results where any constraint violation for any model is extremely small.

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Burnett, James Wesley, and Xueting Zhao. "Spatially Explicit Prediction of Wholesale Electricity Prices." International Regional Science Review 40, no. 2 (July 27, 2016): 99–140. http://dx.doi.org/10.1177/0160017615607055.

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Transmission constraints often limit the flow of electricity in a regional transmission network leading to strong interaction effects across different geographically distributed points within the system. In modern wholesale electricity markets, these transmission constraints lead to spatial patterns within the nodal electricity spot prices. This study exploits these spatial patterns to better predict spot prices within a wholesale electricity market. More specifically, we use the latest spatial panel data econometric models to compare within-sample and out-of-sample forecasts against nonspatial panel data models. The spatial panel data approach is explained by demonstrating a simple network optimization model. We find that a dynamic, spatial panel data model provides the best predictions within a forecasting error context. Our results may suggest that the spatial autocorrelation between node prices extends beyond the current market-defined zonal boundaries, which calls into question whether the zonal boundaries accurately reflect the congestion boundaries within the system.

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38

Chen, Po-Chih, Chia-Ou Chang, W. T. Chang Chien, and Chan-Shin Chou. "Explicit Equations of Motion for Dynamical Systems with Multiple Constraints." Japanese Journal of Applied Physics 45, no. 6A (June 8, 2006): 5286–92. http://dx.doi.org/10.1143/jjap.45.5286.

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Hosseinzadeh, Mehdi, and Emanuele Garone. "An Explicit Reference Governor for the Intersection of Concave Constraints." IEEE Transactions on Automatic Control 65, no. 1 (January 2020): 1–11. http://dx.doi.org/10.1109/tac.2019.2906467.

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Samuelsson, Stefan, and Jerker Ronnberg. "Implicit and explicit use of scripted constraints in lip-reading." European Journal of Cognitive Psychology 5, no. 2 (June 1993): 201–33. http://dx.doi.org/10.1080/09541449308520116.

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Damiani, Lucia, Ariel I. Diaz, Javier Iparraguirre, and Aníbal M. Blanco. "Accelerated particle swarm optimization with explicit consideration of model constraints." Cluster Computing 23, no. 1 (April 27, 2019): 149–64. http://dx.doi.org/10.1007/s10586-019-02933-1.

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A. F. Mohamed, Haider, and Masood Askari and M. Moghavvemi. "Hard Constraints Explicit Model Predictive Control of an Inverted Pendulum." Iraqi Journal for Electrical And Electronic Engineering 6, no. 1 (June 28, 2010): 28–32. http://dx.doi.org/10.33762/eeej.2010.54340.

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Takewaki, Izuru. "Semi-explicit optimal frequency design of chimneys with geometrical constraints." Finite Elements in Analysis and Design 23, no. 1 (August 1996): 37–56. http://dx.doi.org/10.1016/0168-874x(96)00022-4.

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Mitze, R., and M. Mönnigmann. "Dynamic programming for explicit linear MPC with point-symmetric constraints." IFAC-PapersOnLine 53, no. 2 (2020): 6917–22. http://dx.doi.org/10.1016/j.ifacol.2020.12.387.

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Jankov, S. "Constrained deconvolution by explicit correction of fourier components of the unknown distribution." Serbian Astronomical Journal, no. 159 (1999): 31–38. http://dx.doi.org/10.2298/saj9959031j.

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The physical constraints were applied in the problem of deconvolution by explicitly correcting noise affected Fourier components of the unknown distribution. The method gives the constrained estimate optimal in the quadratic sense, i.e. the estimate closest to the exact solution in the Euclidean space of solutions. The properties of the method were theoretically examined and some practical applications in the astronomical spectroscopy have been effected. The method is compared with the similar Fourier spectrum extrapolation procedures; as a consequence application of the method is recommended particularly in the case of low signal-to-noise measurements.

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Kiš, Karol, and Martin Klaučo. "Neural network based explicit MPC for chemical reactor control." Acta Chimica Slovaca 12, no. 2 (October 1, 2019): 218–23. http://dx.doi.org/10.2478/acs-2019-0030.

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Abstract In this paper, implementation of deep neural networks applied in process control is presented. In our approach, training of the neural network is based on model predictive control, which is popular for its ability to be tuned by the weighting matrices and for it respecting the system constraints. A neural network that can approximate the MPC behavior by mimicking the control input trajectory while the constraints on states and control input remain unimpaired by the weighting matrices is introduced. This approach is demonstrated in a simulation case study involving a continuous stirred tank reactor where a multi-component chemical reaction takes place.

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Arimoto, Suguru, Morio Yoshida, Masahiro Sekimoto, and Kenji Tahara. "A Riemannian-Geometry Approach for Modeling and Control of Dynamics of Object Manipulation under Constraints." Journal of Robotics 2009 (2009): 1–16. http://dx.doi.org/10.1155/2009/892801.

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A Riemannian-geometry approach for modeling and control of dynamics of object manipulation under holonomic or non-holonomic constraints is presented. First, position/force hybrid control of an endeffector of a multijoint redundant (or nonredundant) robot under a holonomic constraint is reinterpreted in terms of “submersion” in Riemannian geometry. A force control signal constructed in the image space of the constraint gradient is regarded as a lifting (or pressing) in the direction orthogonal to the kernel space. By means of the Riemannian distance on the constraint submanifold, stability of position control under holonomic constraints is discussed. Second, modeling and control of two-dimensional object grasping by a pair of multijoint robot fingers are challenged, when the object is of arbitrary shape. It is shown that rolling contact constraints induce the Euler equation of motion, in which constraint forces appear as wrench vectors affecting the object. The Riemannian metric is introduced on a constraint submanifold characterized with arclength parameters. An explicit form of the quotient dynamics is expressed in the kernel space with accompaniment of a pair of first-order differential equations concerning the arclength parameters. An extension of Dirichlet-Lagrange's stability theorem to redundant systems under constraints is suggested by introducing a Morse-Lyapunov function.

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SIVARAM, C., KENATH ARUN, and C. A. SAMARTHA. "PHASE-SPACE CONSTRAINTS ON NEUTRINO LUMINOSITIES." Modern Physics Letters A 23, no. 17n20 (June 28, 2008): 1470–77. http://dx.doi.org/10.1142/s0217732308027850.

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While the importance of phase space constraints for gravitational clustering of neutrinos (which are fermions) is well recognized, the explicit use of such constraints to limit neutrino emission from ultra energetic sources has not been stressed. Special and general relativistic phase space constraints are shown to limit neutrino luminosities in compact sources in various situations.

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Paradis, Carole, and Jean-François Prunet. "On the Validity of Morpheme Structure Constraints." Canadian Journal of Linguistics/Revue canadienne de linguistique 38, no. 2 (June 1993): 235–56. http://dx.doi.org/10.1017/s0008413100014766.

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Morpheme structure constraints (MSCs or, equivalently, morphemic constraints), i.e., constraints on underived items, pose a logical problem to any theory claiming that the first input list to the lexicon, i.e., the dictionary (DICT), may contain material which is considered ill-formed by the MSCs of the language. This problem is related to Scobbie’s (1991:1) “interaction problem”, i.e., the need to make explicit the way in which constraints, rules and representations interact. In the case of MSCs, the interaction problem can be stated as follows: how can ill-formed material be present in the DICT if the DICT contains constraints, i.e., MSCs, against ill-formed material? The Theory of Constraints and Repair Strategies (TCRS) proposed by Paradis (1988a, 1988b, 1990, 1993, this volume), along with Optimality Theory (e.g., Itô and Mester, this volume, and McCarthy, this volume) but in contrast with Declarative Phonology (e.g., Scobbie, this volume), claims explicitly that the DICT can contain material which is identified as ill-formed by post-morphemic constraints (see Paradis and Prunet 1989a:331; Bagemihl 1991:641; Paradis and El Fenne 1991, 1992, 1993; and Ulrich 1991 for other instances of underlying ill-formedness). To solve this interaction problem, Paradis (1993, this volume) suggests that phonological constraints are active in the lexicon (the component where words are morphologically derived) and the post-lexical level alone, not in the DICT. Structures of the DICT may be identified as ill-formed only when going through the lexicon. The theory of phonology which emerges from this position clearly contradicts the commonly-held view that DICT entries are constrained by MSCs.

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Yoshimoto, Atsushi, and Patrick Asante. "Inter-Temporal Aggregation for Spatially Explicit Optimal Harvest Scheduling under Area Restrictions." Forest Science 67, no. 5 (September 17, 2021): 587–606. http://dx.doi.org/10.1093/forsci/fxab025.

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Abstract We propose a new approach to solve inter-temporal unit aggregation issues under maximum opening size requirements using two models. The first model is based on Model I formulation with static harvest treatments for harvest activities. This model identifies periodic harvest activities using a set of constraints for inter-temporal aggregation. The second model is based on Model II formulation, which uses dynamic harvest treatments and incorporates periodic harvest activities directly into the model formulation. The proposed approach contributes to the literature on spatially constrained harvest scheduling problems as it allows a pattern of unit aggregation to change across multiple harvests over time, as inter-temporal aggregation under a maximum opening size requirement over period-specific duration. The main idea of the proposed approach for inter-temporal aggregation is to use a multiple layer scheme for a set of spatial constraints, which is adapted from a maximum flow specification in a spatial forest unit network and a sequential triangle connection to create fully connected feasible clusters. By dividing the planning horizon into period-specific durations for different spatial aggregation patterns, the models can complete inter-temporal spatial aggregation over the planning horizon under a maximum opening size requirement per duration.

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