A Tristable Mechanism Configuration Employing Orthogonal Compliant Mechanisms
Guimin Chen, Quentin T. Aten, Shannon Zirbel, Brian D. Jensen, and Larry L. Howell
Tristable mechanisms, or devices with three distinct stable equilibrium positions, have promise for future applications, but the complexities of the tristable behavior have made it difficult to identify configurations that can achieve tristable behavior while meeting practical stress and fabrication ... [J. Mechanisms Robotics 2, 014501 (2009)] published Thu Nov 19, 2009.
Generation of Under-Actuated Manipulators With Nonholonomic Joints From Ordinary Manipulators
Patrick Grosch, Raffaele Di Gregorio, and Federico Thomas
This paper shows how to generate underactuated manipulators by substituting nonholonomic spherical pairs for (holonomic) spherical pairs in ordinary (i.e. not underactuated) manipulators. As a case study, an underactuated manipulator, previously proposed by one of the authors, is demonstrated to be ... [J. Mechanisms Robotics 2, 011005 (2009)] published Thu Nov 19, 2009.
Invariant Description of Rigid Body Motion Trajectories
Joris De Schutter
This paper presents a minimal invariant coordinate-free description of rigid body motion trajectories. Based on a motion model for the instantaneous screw axis, a time-based coordinate-free description consisting of six scalar functions of time is defined. Analytical formulas are presented to obtain ... [J. Mechanisms Robotics 2, 011004 (2009)] published Thu Nov 19, 2009.
The Brachistochrone With a Movable End-Point and the Nonsimultaneous Variations
D. Radomirovic, Dj. Djukic, and L. Cveticanin
In this paper, the necessary and sufficient conditions for minima plane path with a movable end-point are developed. Using the calculus of variations the considered conditions are based on the zero first-order nonsimultaneous variation and on the positive second-order variation in the functional of ... [J. Comput. Nonlinear Dynam. 5, 011007 (2009)] published Wed Nov 18, 2009.
Stationary shocks in periodic highly nonlinear granular chains
Alain Molinari and Chiara Daraio
We study the existence of stationary shock waves in uniform and periodic heterogeneous highly nonlinear granular chains governed by a power-law contact interaction, comparing discrete and continuum approaches, as well as experiments. We report the presence of quasisteady shock fronts without the nee ... [Phys. Rev. E 80, 056602 (2009)] published Tue Nov 17, 2009.
First-order partial differential equations in classical dynamics
B. R. Smith, Jr.
Caratheodory's classic work on the calculus of variations explores in depth the connection between ordinary differential equations and first-order partial differential equations. The n second-order ordinary differential equations of a classical dynamical system reduce to a single first-order differe ... [Am. J. Phys. 77, 1147 (2009)] published Tue Nov 17, 2009.
Autoderivation of Topological Graphs for Type Synthesis of Planar 3DOF Parallel Mechanisms
Yi Lu, Ling Ding, and Jianping Yu
The autoderivation of valid topological graph (TGs) of planar 3DOF parallel mechanisms is studied systematically based on topology embryonic graphs (TEGs) and arrays. First, some TEGs without any binary links are constructed, some paths with only binary links are distributed over the TEGs, and some ... [J. Mechanisms Robotics 2, 011002 (2009)] published Thu Nov 12, 2009.
Effects of Orientation Angles on the Singularity-Free Workspace and Orientation Optimization of the GoughStewart Platform
Qimi Jiang and Clement M. Gosselin
The singularity-free workspace of parallel mechanisms is highly desirable in a context of robot design. This work focuses on analyzing the effects of the orientation angles on the singularity-free workspace of the GoughStewart platform in order to determine the optimal orientation. In any orientatio ... [J. Mechanisms Robotics 2, 011001 (2009)] published Thu Nov 12, 2009.
Dynamic Modeling and Analysis of a Circular Track-Guided Tripod
Yuwen Li, Fengfeng Xi, Allan Daniel Finistauri, and Kamran Behdinan
To enlarge the workspace and improve the motion capability of a parallel robot, the base of the robot can be guided to move along a linear or curved track. This paper aims at analyzing how the motion of the base affects the dynamics of a parallel robot. For this purpose, kinematic and dynamic equati ... [J. Comput. Nonlinear Dynam. 5, 011005 (2009)] published Thu Nov 12, 2009.
Self-Sensing Active Magnetic Dampers for Vibration Control
Angelo Bonfitto, Xavier De Lepine, Mario Silvagni, and Andrea Tonoli
The aim of this paper is to investigate the potential of a self-sensing strategy in the case of an electromagnetic damper for the vibration control of flexible structures and rotors. The study has been performed in the case of a single degree of freedom mechanical oscillator actuated by a couple of ... [J. Dyn. Sys., Meas., Control 131, 061006 (2009)] published Tue Nov 10, 2009.
Self-organized patterns in collections of chains
T. Sykes and T. Mullin
Results are presented of an experimental investigation into patterned segregation in thin layers of poppy seeds and short lengths of metal chains subjected to vibration. Critical phenomena are uncovered and both continuous and discontinuous transitions are observed. A phase diagram for the behavior ... [Phys. Rev. E 80, 051301 (2009)] published Tue Nov 3, 2009.
Modeling of 2D and 3D Assemblies Taking Into Account Form Errors of Plane Surfaces
Serge Samper, Pierre-Antoine Adragna, Hugues Favreliere, and Maurice Pillet
The tolerancing process links the virtual and the real worlds. From the former, tolerances define a variational geometrical language (geometric parameters). From the latter, there are values limiting those parameters. The beginning of a tolerancing process is in this duality. As high precision assem ... [J. Comput. Inf. Sci. Eng. 9, 041005 (2009)] published Mon Nov 2, 2009.
Force network ensemble for the triangular lattice: A tale of tiles
Brian P. Tighe, Adrianne R. T. van Eerd, and Thijs J. H. Vlugt
Abstract not available. [Chaos 19, 041107 (2009)] published Tue Oct 27, 2009.
Hydrodynamic character of the nonequipartition of kinetic energy in binary granular gases
J. Javier Brey and M. J. Ruiz-Montero
The influence of the heating mechanism on the kinetic energy densities of the components of a vibrated granular mixture is investigated. Collisions of the particles with the vibrating wall are inelastic and characterized by two coefficients of normal restitution, one for each of the two species. By ... [Phys. Rev. E 80, 041306 (2009)] published Tue Oct 20, 2009.
Mixing and segregation rates in sheared granular materials
Laura A. Golick and Karen E. Daniels
The vertical size segregation of granular materials, a process commonly associated with the Brazil-nut effect, has generally been thought to proceed faster the greater the size difference of the particles. We experimentally investigate sheared dense bidisperse granular materials as a function of the ... [Phys. Rev. E 80, 042301 (2009)] published Fri Oct 16, 2009.
Collinear central configurations in the n-body problem with general homogeneous potential
Mervin Woodlin and Zhifu Xie
In this paper we investigate the central configurations of collinear n-body problem given by the general law of attraction of the form f(r)=1/r. A method involving analysis skills of some elementary algebra and calculus is presented to study the central configurations in the collinear n-body problem ... [J. Math. Phys. 50, 102901 (2009)] published Fri Oct 16, 2009.
Effect of noise on solid-to-liquid transition in small granular systems under shear
Martin F. Melhus, Igor S. Aranson, Dmitri Volfson, and Lev S. Tsimring
The effect of noise on the solid-to-liquid transition of a dense granular assembly under planar shear is studied numerically using soft-particle molecular dynamics simulations in two dimensions. We focus on small systems in a thin planar Couette cell, examining the bistable region while increasing s ... [Phys. Rev. E 80, 041305 (2009)] published Thu Oct 15, 2009.
Pneumatic Muscle Actuated Equipment for Continuous Passive Motion
Tudor T. Deaconescu and Andrea I. Deaconescu
Applying continuous passive rehabilitation movements as part of the recovery programme of patients with post-traumatic disabilities of the bearing joints of the inferior limbs requires the development of new high performance equipment. This chapter discusses a study of the kinematics and performance ... [AIP Conf. Proc. 1174, 311 (2009)] published Wed Oct 14, 2009.
A Robust Approach to Inventory Optimization Under Uncertainty
Abhilasha Aswal and G. N. Srinivasa Prasanna
In this paper we present an application of robust optimization to inventory optimization under uncertainty. We represent uncertainty in a constraint based framework derived from basic economic principles. This approach offers the ability to use information theoretic concepts to quantify the amount o ... [AIP Conf. Proc. 1174, 117 (2009)] published Wed Oct 14, 2009.
Oscillations of a candle burning at both ends
Stavros Theodorakis and Kalliopi Paridi
A candle burning at both ends will oscillate vertically about the horizontal, forming the popular candle see-saw or stearic motor. The reason for these oscillations is that at any particular instant, more drops of liquid wax drip from the lower end than from the higher one. As a result, the lower si ... [Am. J. Phys. 77, 1049 (2009)] published Mon Oct 12, 2009.
Partitioning of energy in highly polydisperse granular gases
H. Uecker, W. T. Kranz, T. Aspelmeier, and A. Zippelius
A highly polydisperse granular gas is modeled by a continuous distribution of particle sizes, a, giving rise to a corresponding continuous temperature profile, T(a), which we compute approximately, generalizing previous results for binary or multicomponent mixtures. If the system is driven, it evolv ... [Phys. Rev. E 80, 041303 (2009)] published Fri Oct 9, 2009.