A Virtual Cam Method for Locating Instant Centers of Kinematically Indeterminate Linkages

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
Yin-Ping Chang ◽  
Innchyn Her
Keyword(s):  
Degrees Of Freedom ◽  
Graphical Method ◽  
Complete Set ◽  
Loop Chain

Kinematically indeterminate linkages are those whose complete set of instant centers cannot be obtained by Kennedy’s theorem. A linkage of this kind is often characterized as having no four-bar loop, or even if one exists, it does not lead to the finding of all other instant centers in the multiple-loop chain. This paper presents a simple graphical method for dealing with many of these linkages. While not altering the total degrees of freedom of the linkage, a virtual cam is introduced to help locate some key instant centers. This method also lends itself to applications along with Pennock’s method to achieve greater usability.

Successive Synthesis of Substructure Modes

1991 ◽  
Vol 58 (3) ◽  
pp. 759-765 ◽  
Author(s):  
Luis E. Suarez ◽  
Mahendra P. Singh
Keyword(s):  
Closed Form ◽  
Characteristic Equation ◽  
Degrees Of Freedom ◽  
Coupled System ◽  
Closed Form Expression ◽  
Element Discretization ◽  
Root Finding ◽  
Complete Set ◽  
Conventional Solution ◽  
Second Eigenvalue

A mode synthesis approach is presented to calculate the eigenproperties of a structure from the eigenproperties of its substructures. The approach consists of synthesizing the substructures sequentially, one degree-of-freedom at a time. At each coupling stage, the eigenvalue is obtained as the solution of a characteristic equation, defined in closed form in terms of the eigenproperties obtained in the preceding coupling stage. The roots of the characteristic equation can be obtained by a simple Newton-Raphson root finding scheme. For each calculated eigenvalue, the eigenvector is defined by a simple closed-form expression. The eigenproperties obtained in the final coupling stage provide the desired eigenproperties of the coupled system. Thus, the approach avoids a conventional solution of the second eigenvalue problem. The approach can be implemented with the complete set or a truncated number of substructure modes; if the complete set of modes is used, the calculated eigenproperties would be exact. The approach can be used with any finite element discretization of structures. It requires only the free interface eigenproperties of the substructures. Successful application of the approach to a moderate size problem (255 degrees-of-freedom) on a microcomputer is also demonstrated.

scholarly journals TESTING HYPOTHESES ABOUT LINKAGE DISEQUILIBRIUM WITH MULTIPLE ALLELES

Genetics ◽  
1978 ◽  
Vol 88 (3) ◽  
pp. 633-642
Author(s):  
B S Weir ◽  
C Clark Cockerham
Keyword(s):  
Linkage Disequilibrium ◽  
Degrees Of Freedom ◽  
Chi Square ◽  
Multiple Alleles ◽  
Testing Hypotheses ◽  
Allelic Frequencies ◽  
Linkage Disequilibria ◽  
Complete Set

ABSTRACT For loci with multiple alleles, hypotheses about linkage disequilibrium may be tested on the complete set of gametic data, or on various collapsed sets of data. Collapsing data into a few alleles at each locus can change the power of the tests, as implied in a recent paper by Zouros, Golding and Mackay (1977). We show that the nature of such changes can be found from properties of the noncentral chi-square distribution, and that the magnitude and direction of these changes depend on the levels of linkage disequilibria, allelic frequencies and degrees of freedom.

scholarly journals Invariant Graphical Method for Electron-Atom Scattering Coupled-Channel Equations

2011 ◽  
Vol 2011 ◽  
pp. 1-14
Author(s):  
J. B. Wang ◽  
A. T. Stelbovics
Keyword(s):  
Quantum Physics ◽  
Graphical Method ◽  
Matrix Elements ◽  
Many Body ◽  
Atom Scattering ◽  
Efficient Construction ◽  
Core Approximation ◽  
Potential Matrix ◽  
Complete Set ◽  
Coupled Channel

We present application examples of a graphical method for the efficient construction of potential matrix elements in quantum physics or quantum chemistry. The simplicity and power of this method are illustrated through several examples. In particular, a complete set of potential matrix elements for electron-lithium scattering are derived for the first time using this method, which removes the frozen core approximation adopted by previous studies. This method can be readily adapted to study other many-body quantum systems.

The QuadroG Robot, a Parallel Robot With a Configurable Platform for Haptic Applications

2015 ◽  
Author(s):  
Salua Hamaza ◽  
Patrice Lambert ◽  
Marco Carricato ◽  
Just Herder
Keyword(s):  
Kinematic Analysis ◽  
Degrees Of Freedom ◽  
Closed Loop ◽  
Parallel Robot ◽  
Parallel Robots ◽  
End Effector ◽  
Contact Points ◽  
Loop Chain ◽  
End Effectors ◽  
4 Degrees Of Freedom

This paper explores the fundamentals of parallel robots with configurable platforms (PRCP), as well as the design and the kinematic analysis of those. The concept behind PRCP is that the rigid (non-configurable) end-effector is replaced by a closed-loop chain, the configurable platform. The use of a closed-loop chain allows the robot to interact with the environment from multiple contact points on the platform, which reflects the presence of multiple end-effectors. This results in a robot that successfully combines motion and grasping capabilities into a structure that provides an inherent high stiffness. This paper aims to introduce the QuadroG robot, a 4 degrees of freedom PRCP which finely merges planar motion together with grasping capabilities.

Kinematics Analysis of the Crank Mechanism Conveyor Using MSC Adams

2015 ◽  
Vol 816 ◽  
pp. 140-149 ◽  
Author(s):  
Darina Hroncová ◽  
Patrik Šarga
Keyword(s):  
Degrees Of Freedom ◽  
Graphical Method ◽  
Angular Acceleration ◽  
Displacement Velocity ◽  
Kinematics And Dynamics ◽  
Kinematics Analysis ◽  
Analysis Model ◽  
The Individual ◽  
Kinematics Parameters ◽  
Crank Mechanism

The aim of the thesis is the solution of kinematics analysis model of the conveyor with a crank mechanism. For solution is to use a graphical method for determining the kinematics parameters of the individual members of the mechanism. In part kinematics analysis is also used MSC Adams View program that is designed to address the problems of kinematics and dynamics of systems with more degrees of freedom. This program shows the displacement, velocity and acceleration and angular velocity and angular acceleration of members. Finally, the work presents the results with graphic display of parameters such as displacement, velocity and acceleration. Introductory chapters are devoted to general issues kinematics mechanisms and the following chapters are devoted to a particular model of the conveyor mechanism.

Effect of Wind Loads on the Performance of Free-Fall Lifeboats

2014 ◽  
Author(s):  
Thomas Sauder ◽  
Eloise Croonenborghs ◽  
Sebastien Fouques ◽  
Nabila Berchiche ◽  
Svein-Arne Reinholdtsen
Keyword(s):  
Numerical Simulations ◽  
Degrees Of Freedom ◽  
Free Fall ◽  
Offshore Structures ◽  
Water Entry ◽  
Forward Speed ◽  
Cfd Simulations ◽  
Six Degrees Of Freedom ◽  
Complete Set ◽  
Water Exit

The paper presents a model describing the launch of free-fall lifeboats from offshore structures in strong environmental wind. Six-degrees-of-freedom numerical simulations of the lifeboat launch are performed using the free-fall lifeboat simulator VARUNA with a complete set of wind coefficients for the lifeboat. Those wind coefficients are obtained by CFD simulations validated against wind tunnel tests. The lifeboat launch simulations are then verified against time-domain CFD simulations of the whole launch in air until water entry. It is shown by means of numerical simulations that wind-induced loads on the lifeboat have a strong influence on its kinematics until water entry, and subsequently on the acceleration loads experienced by the occupants, on the structural loads on the lifeboat, and on its forward speed after water exit. It is concluded that the effect of wind-induced loads on the lifeboat performances should in general be investigated when establishing the operational limits for a given offshore installation.

scholarly journals A PURE DIRAC'S CANONICAL ANALYSIS FOR FOUR-DIMENSIONAL BF THEORIES

2012 ◽  
Vol 09 (07) ◽  
pp. 1250053 ◽  
Author(s):  
ALBERTO ESCALANTE ◽  
I. RUBALCAVA-GARCÍA
Keyword(s):  
Lie Algebra ◽  
Degrees Of Freedom ◽  
Canonical Analysis ◽  
Gauge Transformations ◽  
Bf Theory ◽  
Extended Action ◽  
Complete Set

We perform Dirac's canonical analysis for a four-dimensional BF and for a generalized four-dimensional BF theory depending on a connection valued in the Lie algebra of SO(3, 1). This analysis is developed by considering the corresponding complete set of variables that define these theories as dynamical, and we find out the relevant symmetries, the constraints, the extended Hamiltonian, the extended action, gauge transformations and the counting of physical degrees of freedom. The results obtained are compared with other approaches found in the literature.

scholarly journals Quantum error correction and holographic information from bilocal holography

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Robert de Mello Koch ◽  
Eunice Gandote ◽  
Nirina Hasina Tahiridimbisoa ◽  
Hendrik J.R. Van Zyl
Keyword(s):  
Degrees Of Freedom ◽  
Gravitational Theory ◽  
Quantum Error Correction ◽  
Constructive Approach ◽  
Gauge Invariant ◽  
Higher Spin ◽  
Ads Spacetime ◽  
Complete Set ◽  
Quantum Error ◽  
Boundary Mapping

Abstract Bilocal holography is a constructive approach to the higher spin theory holographically dual to O(N ) vector models. In contrast to other approaches to bulk reconstruction, bilocal holography does not take input from the dual gravitational theory. The resulting map is a complete bulk/boundary mapping in that it maps the complete set of O(N ) invariant degrees of freedom in the CFT, to the complete set of higher spin degrees of freedom. After restricting to a suitable code subspace we demonstrate that bilocal holography naturally reproduces the quantum error correcting properties of holography and it gives a robust bulk (entanglement wedge) reconstruction. A gauge invariant entangled pair of CFT degrees of freedom are naturally smeared over a semicircle in the bulk spacetime, which is highly suggestive of bit threads. Finally, we argue that finite N relations in the CFT, when interpreted in the dual AdS spacetime, can provide relations between degrees of freedom located near the boundary and degrees of freedom deep in the bulk.

scholarly journals Creation and control of high-dimensional multi-partite classically entangled light

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Yijie Shen ◽  
Isaac Nape ◽  
Xilin Yang ◽  
Xing Fu ◽  
Mali Gong ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
State Of The Art ◽  
Structured Light ◽  
High Dimensional ◽  
Complete Set ◽  
Quantum Entangled States ◽  
Tomography Method ◽  
And Control ◽  
Light Beams ◽  
First Time

AbstractVector beams, non-separable in spatial mode and polarisation, have emerged as enabling tools in many diverse applications, from communication to imaging. This applicability has been achieved by sophisticated laser designs controlling the spin and orbital angular momentum, but so far is restricted to only two-dimensional states. Here we demonstrate the first vectorially structured light created and fully controlled in eight dimensions, a new state-of-the-art. We externally modulate our beam to control, for the first time, the complete set of classical Greenberger–Horne–Zeilinger (GHZ) states in paraxial structured light beams, in analogy with high-dimensional multi-partite quantum entangled states, and introduce a new tomography method to verify their fidelity. Our complete theoretical framework reveals a rich parameter space for further extending the dimensionality and degrees of freedom, opening new pathways for vectorially structured light in the classical and quantum regimes.

Evaluation of the Impact of Observations on Analyses in 3D- and 4D-Var Based on Information Content

2011 ◽  
Vol 139 (3) ◽  
pp. 726-737 ◽  
Author(s):  
Cristina Lupu ◽  
Pierre Gauthier ◽  
Stéphane Laroche
Keyword(s):  
Data Assimilation ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Practical Method ◽  
A Posteriori ◽  
Error Statistics ◽  
One Dimensional ◽  
Complete Set ◽  
Analysis System ◽  
The Impact

Abstract The degrees of freedom for signal (DFS) is used in data assimilation applications to measure the self-sensitivity of analysis to different observation types. This paper describes a practical method to estimate the DFS of observations from a posteriori statistics. The method does not require the consistency of the error statistics in the analysis system and it is shown that the observational impact on analyses can be estimated from observation departures with respect to analysis or the forecast. This method is first introduced to investigate the impact of a complete set, or subsets, of observations on the analysis for idealized one-dimensional variational data assimilation (1D-Var) analysis experiments and then applied in the framework of the three dimensional (3D)- and four-dimensional (4D)-Var schemes developed at Environment Canada.

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