Constraint Jacobians for Constant-Time Inverse Kinematics
Constraint Jacobians for Constant-Time Inverse Kinematics and Assembly Optimization Donald Nelson be used in conjunction with other numerical methods to solve for a variety of kinematics, dynamics for Constant-Time Inverse Kinematics and Assembly Optimization Donald D. Nelson University of Utah Computer
Maddock, Steve
Real-Time Inverse Kinematics: The Return of the Jacobian 1 Real-Time Inverse Kinematics: The Return Kingdom E-mail: M.Meredith@dcs.shef.ac.uk, S.Maddock@dcs.shef.ac.uk KEYWORDS Inverse Kinematics, Computer of an inverse kinematics solver. However, because of their iterative nature, such methods can be slow. So far
Using a Half-Jacobian for Real-Time Inverse Kinematics Michael Meredith & Steve Maddock
Maddock, Steve
Using a Half-Jacobian for Real-Time Inverse Kinematics Michael Meredith & Steve Maddock Department.Maddock@dcs.shef.ac.uk KEYWORDS Inverse Kinematics, Computer Character Animation, Real-time ABSTRACT Due to their scalability, numerical techniques often form part of an inverse kinematics (IK) solver. However, because
JFKengine: A Jacobian and Forward Kinematics Generator
Fischer, K.N.
2003-02-13
During robot path planning and control the equations that describe the robot motions are determined and solved. Historically these expressions were derived analytically off-line. For robots that must adapt to their environment or perform a wide range of tasks, a way is needed to rapidly re-derive these expressions to take into account the robot kinematic changes, such as when a tool is added to the end-effector. The JFKengine software was developed to automatically produce the expressions representing the manipulator arm motion, including the manipulator arm Jacobian and the forward kinematic expressions. Its programming interface can be used in conjunction with robot simulation software or with robot control software. Thus, it helps to automate the process of configuration changes for serial robot manipulators. If the manipulator undergoes a geometric change, such as tool acquisition, then JFKengine can be invoked again from the control or simulation software, passing it parameters for the new arm configuration. This report describes the automated processes that are implemented by JFKengine to derive the kinematic equations and the programming interface by which it is invoked. Then it discusses the tree data structure that was chosen to store the expressions, followed by several examples of portions of expressions as represented in the tree. The C++ classes and their methods that implement the expression differentiation and evaluation operations are described. The algorithms used to construct the Jacobian and forward kinematic equations using these basic building blocks are then illustrated. The activity described in this report is part of a larger project entitled ''Multi-Optimization Criteria-Based Robot Behavioral Adaptability and Motion Planning'' that focuses on the development of a methodology for the generalized resolution of robot motion equations with time-varying configurations, constraints, and task objective criteria. A specific goal of this project is the implementation of this generalized methodology in a single general code that would be applicable to the motion planning of a wide class of systems and would automate many of the processes involved in developing and solving the motion planning and controls equations. This project is funded by the U.S. Department of Energy's Environmental Management Science Program (DOE-EMSP) as project EMSP no. 82794 and is transitioning to the DOE-Office of Biological and Environmental Research (OBER) as per FY-02.
Real-Time Inverse Kinematics Techniques for Anthropomorphic Limbs
Deepak Tolani; Ambarish Goswami; Norman I. Badler
2000-01-01
In this paper we develop a set of inverse kinematics algorithms suitable for an anthropomorphic arm or leg. We use a combination of analytical and numeri-cal methods to solve generalized inverse kinematics problems including position, orientation, and aiming constraints. Our combination of analytical and numerical methods results in faster and more reliable algorithms than conventional inverse Jacobian and optimization-based techniques.
Unseren, M.A.; Reister, D.B.
1995-07-01
A method for kinematically modeling a constrained rigid body mechanical system and a method for controlling such a system termed input relegation control (IRC) were applied to resolve the kinematic redundancy of a serial link manipulator moving in an open chain configuration in. A set of equations was introduced to define a new vector variable parameterizing the redundant degrees of freedom (DOF) as a linear function of the joint velocities. The new set was combined with the classical kinematic velocity model of manipulator and solved to yield a well specified solution for the joint velocities as a function of the Cartesian velocities of the end effector and of the redundant DOF variable. In the previous work a technique was proposed for selecting the matrix relating the redundant DOF variable to the joint velocities which resulted in it rows being orthogonal to the rows of the Jacobian matrix. The implications for such a selection were not discussed in. In Part 1 of this report a basis for the joint space is suggested which provides considerable insight into why picking the aforementioned matrix to be orthogonal to the Jacobian is advantageous. A second objective of Part 1 is to compare the IRC method to the Extended Jacobian method of Baillieul and Martin and other related methods.
NASA Technical Reports Server (NTRS)
Hsia, T. C.; Lu, G. Z.; Han, W. H.
1987-01-01
In advanced robot control problems, on-line computation of inverse Jacobian solution is frequently required. Parallel processing architecture is an effective way to reduce computation time. A parallel processing architecture is developed for the inverse Jacobian (inverse differential kinematic equation) of the PUMA arm. The proposed pipeline/parallel algorithm can be inplemented on an IC chip using systolic linear arrays. This implementation requires 27 processing cells and 25 time units. Computation time is thus significantly reduced.
Style-based inverse kinematics
Keith Grochow; Steven L. Martin; Aaron Hertzmann; Zoran Popovic
2004-01-01
This paper presents an inverse kinematics system based on a learned model of human poses. Given a set of constraints, our system can produce the most likely pose satisfying those constraints, in real-time. Training the model on different input data leads to different styles of IK. The model is represented as a probability distribution over the space of all possible
A repeatable inverse kinematics algorithm with linear invariant subspaces for mobile manipulators.
Tcho?, Krzysztof; Jakubiak, Janusz
2005-10-01
On the basis of a geometric characterization of repeatability we present a repeatable extended Jacobian inverse kinematics algorithm for mobile manipulators. The algorithm's dynamics have linear invariant subspaces in the configuration space. A standard Ritz approximation of platform controls results in a band-limited version of this algorithm. Computer simulations involving an RTR manipulator mounted on a kinematic car-type mobile platform are used in order to illustrate repeatability and performance of the algorithm. PMID:16240778
Fatigue Exploitation in an Inverse Kinematics Framework
RodrÃguez, Inmaculada
Chapter 5 Fatigue Exploitation in an Inverse Kinematics Framework 5.1 Introduction As was seen in such a way that fatigue evolution over time can be exploited. Fatigue is then applied to postures optimization and characterization. #12;Chapter 5 Fatigue Exploitation in an Inverse Kinematics Framework 80 5
An inverse kinematic solution for kinematically redundant robot manipulators
NASA Astrophysics Data System (ADS)
Oh, S.-Y.; Bach, M.; Orin, D.
The computation of the sequence of joint motion on the basis of the Cartesian motion of an interested member is addressed by an inverse kinematic analysis that is based on a Newton-Raphson numerical procedure. This procedure may be applied to the solution of the inverse kinematic problem for a manipulator of any mechanical configuration without having to derive a closed form solution beforehand. The technique is applicable to redundant manipulators, since additional constraints on other members, as well as on the end effector, may be imposed. The approach is presently applied to a seven-degree-of-freedom manipulator, and its obstacle-avoidance capability is demonstrated.
Inverse kinematic-based robot control
NASA Technical Reports Server (NTRS)
Wolovich, W. A.; Flueckiger, K. F.
1987-01-01
A fundamental problem which must be resolved in virtually all non-trivial robotic operations is the well-known inverse kinematic question. More specifically, most of the tasks which robots are called upon to perform are specified in Cartesian (x,y,z) space, such as simple tracking along one or more straight line paths or following a specified surfacer with compliant force sensors and/or visual feedback. In all cases, control is actually implemented through coordinated motion of the various links which comprise the manipulator; i.e., in link space. As a consequence, the control computer of every sophisticated anthropomorphic robot must contain provisions for solving the inverse kinematic problem which, in the case of simple, non-redundant position control, involves the determination of the first three link angles, theta sub 1, theta sub 2, and theta sub 3, which produce a desired wrist origin position P sub xw, P sub yw, and P sub zw at the end of link 3 relative to some fixed base frame. Researchers outline a new inverse kinematic solution and demonstrate its potential via some recent computer simulations. They also compare it to current inverse kinematic methods and outline some of the remaining problems which will be addressed in order to render it fully operational. Also discussed are a number of practical consequences of this technique beyond its obvious use in solving the inverse kinematic question.
ReguIarization of Inverse Kinematics for Manipulators Using Neural Network Inversions
Lu, Bao-Liang
ReguIarization of Inverse Kinematics for Manipulators Using Neural Network Inversions Bao-Liang Lul a new approach to regularizingthe inverse kinematics problem for redun- dant manipulators using neural kinematic function. In the third phase, the multiple inverse kinematic solutions for a desired end
An Inverse Kinematics Method Based on Muscle Dynamics Taku Komura
Subramanian, Sriram
An Inverse Kinematics Method Based on Muscle Dynamics Taku Komura Image Information Division, RIKEN an inverse kinematics algorithm that takes the characteristics of human bodies into account to create natural human animation. 1 Introduction Inverse kinematics is a well-known technique for creat
INDIVIDUALISED CHARACTER MOTION USING WEIGHTED REAL-TIME INVERSE KINEMATICS
Maddock, Steve
INDIVIDUALISED CHARACTER MOTION USING WEIGHTED REAL-TIME INVERSE KINEMATICS Michael Meredith Individualisation, Real-time Inverse Kinematics, Weighted IK Chains, Injury Simulation ABSTRACT In this paper we present a technique that enhances an inverse kinematics (IK) solver such that when the results are applied
Solving Inverse Kinematics Constraint Problems for Highly Articulated Models
Waterloo, University of
Solving Inverse Kinematics Constraint Problems for Highly Articulated Models by Kang Teresa Ge to achieve the goal is an inverse kinematics problem. Redundancy of the degrees of freedom (DOF) can be used also be considered, as can loops. Solutions to redundant inverse kinematic problems are well developed
NASA Astrophysics Data System (ADS)
Lin, J.; Lin, C. C.; Lo, H.-S.
2009-10-01
Interest in complex robotic systems is growing in new application areas. An example of such a robotic system is a dexterous manipulator mounted on an oscillatory base. In literature, such systems are known as macro/micro systems. This work proposes pseudo-inverse Jacobian feedback control laws and applies grey relational analysis for tuning outer-loop PID control parameters of Cartesian computed-torque control law for robotic manipulators mounted on oscillatory bases. The priority when modifying controller parameters should be the top ranking importance among parameters. Grey relational grade is utilized to investigate the sensitivity of tuning the auxiliary signal PID of the Cartesian computed-torque law to achieve desired performance. Results of this study can be feasible to numerous mechanical systems, such as mobile robots, gantry cranes, underwater robots, and other dynamic systems mounted on oscillatory bases, for moving the end-effector to a desired Cartesian position.
Wrist-Partitioned, Inverse Kinematic Accelerations and Manipulator Dynamics
John M. Hollerbach; Gideon Sahar
1983-01-01
An efficient algorithm is presented for the calculation of the inverse kinematic accelerations for a six-degree-of-freedom manipulator with a spherical wrist. The inverse kinematic calculation is shown to work synergistically with the inverse dynamic calculation, producing kinematic parameters needed in the recursive Newton-Euler dynamics formulation. Additional savings in the dynamic computation are noted for a class of kinematically well-structured manipulators,
A Geometrical Approach to Inverse Kinematics for Continuum Manipulators
A Geometrical Approach to Inverse Kinematics for Continuum Manipulators Srinivas Neppalli, Matthew Abstract--We present a new geometrical approach to solving inverse kinematics for continuous backbone (continuum) robot manipulators. First, this paper presents a solution to the in- verse kinematics problem
Inverse kinematics positioning using nonlinear programming for highly articulated figures
Jianmin Zhao; Norman I. Badler
1994-01-01
An articulated figure is often modeled as a set of rigid segments connected with joints. Its configuration can be altered by varying the joint angles. Although it is straight forward to compute figure configurations given joint angles (forward kinematics), it is more difficult to find the joint angles for a desired configuration (inverse kinematics). Since the inverse kinematics problem is
ON THE INVERSE KINEMATICS OF A FRAGMENT OF PROTEIN BACKBONE
Pratt, Vaughan
ON THE INVERSE KINEMATICS OF A FRAGMENT OF PROTEIN BACKBONE Guanfeng Liu, R.J. Milgram, A. Dhanik studies the structure of the inverse kinematics (IK) map of a fragment of protein backbone with 6 and position maps are computed for a slightly idealized kinematic model. They yield a decomposition of SO(3
To appear in SIGGRAPH 2005. Mesh-Based Inverse Kinematics
Lehmann, Daniel
To appear in SIGGRAPH 2005. Mesh-Based Inverse Kinematics Robert W. Sumner Matthias Zwicker Craig. However, the class of meaning- ful deformations varies from mesh to mesh and depends on mesh kinematics an anal- ogy to the traditional use of skeleton-based inverse kinematics for posing skeletons, we define
A Simplified Scheme for Kinematic Source Inversion
NASA Astrophysics Data System (ADS)
Iglesias, A.; Castro-Artola, O.; Singh, S.; Hjorleifsdottir, V.; Legrand, D.
2013-05-01
It is well known that different kinematic source inversion schemes lead to non-unique solutions. For this reason, a simplified scheme, which yields the main characteristics of the rupture process, rather than the details, may be desirable. In this work we propose a modification of the frequency-domain inversion scheme of Cotton & Campillo (1995) to extract kinematic parameters using simplified geometries (ellipses). The forward problem is re-parameterized by including one or two ellipses in which the displacement is smoothly distributed. For the ellipses we invert for the position of the centers within the fault plane, the major and minor semi-axes, the maximum displacements, the angles of rotation and a parameter that controls the distribution of slip. A simulated annealing scheme is used to invert near-source displacements. We first test the method on synthetic displacement records corresponding to the Guerrero-Oaxaca earthquake (20/03/2012, Mw=7.5) by comparing the results obtained from the modified technique with the original method. In the next step, we use displacements obtained by double numerical integration of recorded accelerograms. We find that, in spite of the simple geometry, the modified method leads to a good fit between observed and synthetic displacements and recovers the main rupture characteristics.
INVERSE KINEMATICS AND SINGULARITIES OF MANIPULATORS WITH OFFSET WRIST
Williams II, Robert L.
1 INVERSE KINEMATICS AND SINGULARITIES OF MANIPULATORS WITH OFFSET WRIST Robert L. Williams II of Robotics and Automation Vol. 14, No. 1, pp. 1-8 1999 Contact information: Robert L. Williams II Member;2 INVERSE KINEMATICS AND SINGULARITIES OF MANIPULATORS WITH OFFSET WRIST Robert L. Williams II Assistant
Forward and inverse kinematics of double universal joint robot wrists
NASA Technical Reports Server (NTRS)
Williams, Robert L., II
1991-01-01
A robot wrist consisting of two universal joints can eliminate the wrist singularity problem found on many individual robots. Forward and inverse position and velocity kinematics are presented for such a wrist having three degrees of freedom. Denavit-Hartenberg parameters are derived to find the transforms required for the kinematic equations. The Omni-Wrist, a commercial double universal joint robot wrist, is studied in detail. There are four levels of kinematic parameters identified for this wrist; three forward and three inverse maps are presented for both position and velocity. These equations relate the hand coordinate frame to the wrist base frame. They are sufficient for control of the wrist standing alone. When the wrist is attached to a manipulator arm; the offset between the two universal joints complicates the solution of the overall kinematics problem. All wrist coordinate frame origins are not coincident, which prevents decoupling of position and orientation for manipulator inverse kinematics.
Inverse kinematics problem in robotics using neural networks
NASA Technical Reports Server (NTRS)
Choi, Benjamin B.; Lawrence, Charles
1992-01-01
In this paper, Multilayer Feedforward Networks are applied to the robot inverse kinematic problem. The networks are trained with endeffector position and joint angles. After training, performance is measured by having the network generate joint angles for arbitrary endeffector trajectories. A 3-degree-of-freedom (DOF) spatial manipulator is used for the study. It is found that neural networks provide a simple and effective way to both model the manipulator inverse kinematics and circumvent the problems associated with algorithmic solution methods.
NASA Astrophysics Data System (ADS)
Akli, Isma; Achour, Noura
2008-06-01
This article presents a differential kinematic study for a car-like mobile system carrying a four degrees of freedom manipulator. The generalized coordinates and velocities of the mobile manipulator are required, when the position and the velocity of the end-effector are imposed in the cartesian space. Our approach consists of planning the motion of the mobile platform with make the onboard manipulator able to follow the cartesian trajectory. The resulted generalized coordinates are exploited to calculate the Forward Differential Kinematic Model. Since the mobile manipulator is redundant regarding to the task, we profit from the system characteristics to augment the jacobian matrix, while integrating additional constraints, to inverse the differential kinematic model.
Computational neural learning formalisms for manipulator inverse kinematics
NASA Technical Reports Server (NTRS)
Gulati, Sandeep; Barhen, Jacob; Iyengar, S. Sitharama
1989-01-01
An efficient, adaptive neural learning paradigm for addressing the inverse kinematics of redundant manipulators is presented. The proposed methodology exploits the infinite local stability of terminal attractors - a new class of mathematical constructs which provide unique information processing capabilities to artificial neural systems. For robotic applications, synaptic elements of such networks can rapidly acquire the kinematic invariances embedded within the presented samples. Subsequently, joint-space configurations, required to follow arbitrary end-effector trajectories, can readily be computed. In a significant departure from prior neuromorphic learning algorithms, this methodology provides mechanisms for incorporating an in-training skew to handle kinematics and environmental constraints.
An adaptive inverse kinematics algorithm for robot manipulators
NASA Technical Reports Server (NTRS)
Colbaugh, R.; Glass, K.; Seraji, H.
1990-01-01
An adaptive algorithm for solving the inverse kinematics problem for robot manipulators is presented. The algorithm is derived using model reference adaptive control (MRAC) theory and is computationally efficient for online applications. The scheme requires no a priori knowledge of the kinematics of the robot if Cartesian end-effector sensing is available, and it requires knowledge of only the forward kinematics if joint position sensing is used. Computer simulation results are given for the redundant seven-DOF robotics research arm, demonstrating that the proposed algorithm yields accurate joint angle trajectories for a given end-effector position/orientation trajectory.
Todorov, Emanuel
From Inverse Kinematics to Optimal Control Perle Geoffroy,, Nicolas Mansard, Maxime Raison, Sofiane that inverse kinematics can be seen as singular case of it, when the preview horizon collapses. Key words: optimal control,inverse kinematics, differential dynamic programming 1 Introduction Both inverse geometry
Robust Modular Inverse Kinematics for Gesture Imitation in an Upper-Body Humanoid Robot
Huang, Zhiyong
Robust Modular Inverse Kinematics for Gesture Imitation in an Upper-Body Humanoid Robot Keng Peng units, and solve the inverse kinematics in a modular fashion based on the derivative of the inverse tangent function of the relevant task space variables. For robustness to kinematic singularity, we add
Maddock, Steve
Adapting Motion Capture Data using Weighted Real-Time Inverse Kinematics Michael Meredith & Steve.Maddock}@dcs.shef.ac.uk Abstract In this paper we present a technique that enhances an inverse kinematics (IK) solver. As the individualisation aspect of our technique is very tightly coupled with the inverse kinematics solver, we can achieve
Numerical Methods for Inverse Kinematics Niels Joubert, UC Berkeley, CS184
O'Brien, James F.
Numerical Methods for Inverse Kinematics Niels Joubert, UC Berkeley, CS184 2008-11-25 Inverse Kinematics is used to pose models by specifying endpoints of segments rather than individual joint angles. We will go through the steps of deriving a simple inverse kinematics problem. We are given a model
Inverse Kinematics for a Serial Chain with Joints under Distance Constraints
Rudolph, Lee
Inverse Kinematics for a Serial Chain with Joints under Distance Constraints Li Han and Lee Rudolph, lrudolph]@clarku.edu Abstract-- Inverse kinematics (IK) problems are important in the study of robotics limits and link collision-free constraints, a common approach in studies of inverse kinematics). We
Reexamination of 6Li +p elastic scattering in inverse kinematics
NASA Astrophysics Data System (ADS)
Soukeras, V.; Pakou, A.; Cappuzzello, F.; Acosta, L.; Agodi, C.; Alamanos, N.; Bondi, M.; Carbone, D.; Cavallaro, M.; Cunsolo, A.; De Napoli, M.; Di Pietro, A.; Fernández-García, J. P.; Figuera, P.; Fisichella, M.; Foti, A.; Keeley, N.; Marquinez-Duran, G.; Martel, I.; Mazzocco, M.; Nicolosi, D.; Pierroutsakou, D.; Rusek, K.; Sgouros, O.; Stiliaris, E.; Strano, E.; Torresi, D.
2015-05-01
Elastic-scattering measurements have been performed for the 6Li +p system in inverse kinematics at the energies of 16, 20, 25, and 29 MeV. The heavy ejectile was detected by the large acceptance MAGNEX spectrometer at the Laboratori Nazionali del Sud in Catania, Italy. The results are considered in a Jeukenne-Lejeune-Mahaux and a continuum discretized coupled-channel calculation framework.
Production of Radioactive Nuclides in Inverse Reaction Kinematics
E. Traykov; A. Rogachevskiy; U. Dammalapati; P. Dendooven; O. C. Dermois; K. Jungmann; C. J. G. Onderwater; M. Sohani; L. Willmann; H. W. Wilschut; A. R. Young
2006-08-08
Efficient production of short-lived radioactive isotopes in inverse reaction kinematics is an important technique for various applications. It is particularly interesting when the isotope of interest is only a few nucleons away from a stable isotope. In this article production via charge exchange and stripping reactions in combination with a magnetic separator is explored. The relation between the separator transmission efficiency, the production yield, and the choice of beam energy is discussed. The results of some exploratory experiments will be presented.
Inverse Kinematics for a Point-Foot Quadruped Robot with Dynamic Redundancy Resolution
Tedrake, Russ
Inverse Kinematics for a Point-Foot Quadruped Robot with Dynamic Redundancy Resolution Alexander to formulate a function to compute forward kinematics of the center of mass of the robot as a function which projects single-leg inverse kinematic solutions into the nullspace. This hybrid approach seems
A Unified Geometric Approach for Inverse Kinematics of a Spatial Chain with Spherical Joints
Han, Li
A Unified Geometric Approach for Inverse Kinematics of a Spatial Chain with Spherical Joints Li Han with spherical joints, where they serve very well for the study of forward kinematics (FK). However, the inverse kinematics (IK) problem is very difficult to solve directly using these angular parameters, on which complex
Inverse kinematics equation of 6DOF robot based on geometry projection and simulation
Zhijian Gou; Ying Sun; Haiying Yu
2010-01-01
There has been the method of neural networks, optimization algorithms and so on to solving inverse kinematics problems in recent years. In this paper, the kinematics equations of the ABB IRB-1400 spot welding robot with 6-degree of freedom which found on the D-H matrix method have been set up. Based on the method of geometry projection principle, the inverse kinematics
A novel inverse kinematics algorithm based on unidirectional search
NASA Astrophysics Data System (ADS)
Lee, Young Dae; Kim, Kee Hwan
2005-12-01
In this paper, we propose a novel algorithm can exactly solve the inverse kinematics of a robot manipulator which does not have the closed form solution. The conventional numerical methods suggested by others have a weak point that they do not consider the feasible joint region of solution. Moreover they are likey to saddle on local points not on the real optimal points of solutions. In this work, we consider the inver kinematics problem as a kind of fixed point problem and propose a solution approach based on unidirectional search and boundary reflection algorithm which can guarantee the global optimal solution and the feasible range of joint limits. Futhermore we present an acceleration idea based upon Steffenson iteration which can speed up the search. Simulation results show the validity and efficiency of our approach.
Jacobi inversion on strata of the Jacobian of the $C_{rs}$ curve $y^r = f(x)$. II
Matsutani, Shigeki
2010-01-01
Continuing previous work by the authors (J. Math. Soc. Japan 60 (2008) 1009-1044), this paper gives the precise order of vanishing of the $\\sigma$-function on a stratification of the Jacobian of a cyclic $C_{rs}$ curve. The result is expressed through combinatorial properties of the Schur functions, related to the stratification of Sato's infinite-dimensional Grassmann manifold.
Kinematic Waveform Inversion: Application in Southwest Iberia Seismicity
NASA Astrophysics Data System (ADS)
Domingues, A. L.; Custodio, S.; Cesca, S.
2011-12-01
The seismic activity that affects the Portuguese territory occurs mainly and more frequently offshore, in the south and southwest of Mainland Portugal. The study of the Portuguese seismicity is conditioned by the poor azimuthal coverage, due to the geographic location of Portugal, and by the large sedimentary basin west of the straight of Gibraltar (Cadiz Basin). In this work we focus on the study of regional seismicity in Portugal (mostly offshore earthquakes) using a recently developed package - the KIWI (Kinematic Waveform Inversion) tools. This new technique performs point and finite source inversions at regional distances. The KIWI routine is a multi-step approach composed of 3 steps, finding different source parameters at different steps. At first, we assume a point source approximation. We initially retrieve the focal mechanism of the earthquake (strike, dip, and rake), the seismic scalar moment M0 and the depth. This inversion step is performed in the spectral domain, by fitting amplitude spectra. In the second step, compressive and dilatation quadrants are retrieved, which is carried out in the time domain. Refined latitude and longitude for the centroid, as well as an earthquake origin time, are also given at this time. The final step of the inversion consists of a simplified finite-fault inversion. We assume the eikonal source model, and determine parameters such as the fault plane orientation (discrimination between fault and auxiliary plane), radius (rupture extension), nucleation point coordinates (indicative of directivity effects) and average rupture velocity of the earthquake. This inversion is performed in the frequency domain by fitting amplitude spectra in a wider frequency band (including higher frequencies). This multi-step approach has the advantage of using different inversion methods, seismic phases and range of frequencies to infer specific parameters. In this work we study 17 regional earthquakes occurred in Southwest Iberia between 2007 and 2009 with moderate magnitude (3.3 to 4.4). The small magnitude of these earthquakes prevents their study with the third step of the algorithm. The solutions obtained are evaluated by a quality criteria and compared with other moment tensor solutions. The quality factor is based on the number of stations and on the misfit between the recorded and the synthetic waveforms. Apart from this study another offshore event was analyzed. The earthquake occurred SW of St Vincent Cape on February 12, 2007 with Mw 5.9. In this study the KIWI tools were employed to infer both the point and finite source parameters of this earthquake. The results of the kinematic source inversion step indicate that the 2007 HAP earthquake ruptured a plane trending WNW-ESE, whereas previous studies suggest that the conjugate fault plane (ENE-WSW) is the true rupture plane. The proposed solution also indicates that the earthquake occurred within the SWIM fault-zone. However, the 46° dip is difficult to reconcile with the sub-vertical nature of the SWIM faults.
Advanced control schemes and kinematic analysis for a kinematically redundant 7 DOF manipulator
NASA Technical Reports Server (NTRS)
Nguyen, Charles C.; Zhou, Zhen-Lei
1990-01-01
The kinematic analysis and control of a kinematically redundant manipulator is addressed. The manipulator is the slave arm of a telerobot system recently built at Goddard Space Flight Center (GSFC) to serve as a testbed for investigating research issues in telerobotics. A forward kinematic transformation is developed in its most simplified form, suitable for real-time control applications, and the manipulator Jacobian is derived using the vector cross product method. Using the developed forward kinematic transformation and quaternion representation of orientation matrices, we perform computer simulation to evaluate the efficiency of the Jacobian in converting joint velocities into Cartesian velocities and to investigate the accuracy of Jacobian pseudo-inverse for various sampling times. The equivalence between Cartesian velocities and quaternion is also verified using computer simulation. Three control schemes are proposed and discussed for controlling the motion of the slave arm end-effector.
Jacobi inversion on strata of the Jacobian of the $C_{rs}$ curve $y^r = f(x)$. II
Shigeki Matsutani; Emma Previato
2012-09-29
Previous work by the authors (this journal, \\vol{60} (2008), 1009-1044) produced equations that hold on certain loci of the Jacobian of a cyclic $C_{rs}$ curve. A curve of this type generalizes elliptic curves, and the equations in question are given in terms of (Klein's) generalization of Weierstrass' $\\sigma$-function. The key tool is a matrix with entries that are polynomial in the coordinates of the affine plane model of the curve, thus can be expressed in terms of $\\sigma$ and its derivatives. The key geometric loci on the Jacobian of the curve give a stratification of Brill-Noether type. The results are of the type of Riemann-Kempf singularity theorem, the methods are germane to those used by J.D. Fay, who gave vanishing tables for Riemann's $\\theta$-function and its derivatives. The main objects we use were developed by several contemporary authors, aside from the classical definitions: meromorphic differentials were expressed in terms of the coordinates mainly by V.M. Buchstaber, J.C. Eilbeck, V.Z. Enolski, D.V. Leykin, and Taylor expansions for $\\sigma$ in terms of Schur polynomials also contributed by A. Nakayashiki, in terms of Sato's $\\tau$-function. Within this framework, following specific results for $\\sigma$-derivatives given by Y. \\^Onishi, we arrive at our main results, namely statements on the vanishing on given strata of the partial derivatives of $\\sigma$ indexed by Young-diagrams subsets that can be worked out in terms of the Weierstrass semigroup of the curve at its point at infinity. The combinatorial statements hold not only for Jacobians but for the stratification of Sato's infinite-dimensional Grassmann manifold as well.
Seeing the world topsy-turvy: The primary role of kinematics in biological motion inversion effects
Fitzgerald, Sue-Anne; Brooks, Anna; van der Zwan, Rick; Blair, Duncan
2014-01-01
Physical inversion of whole or partial human body representations typically has catastrophic consequences on the observer's ability to perform visual processing tasks. Explanations usually focus on the effects of inversion on the visual system's ability to exploit configural or structural relationships, but more recently have also implicated motion or kinematic cue processing. Here, we systematically tested the role of both on perceptions of sex from upright and inverted point-light walkers. Our data suggest that inversion results in systematic degradations of the processing of kinematic cues. Specifically and intriguingly, they reveal sex-based kinematic differences: Kinematics characteristic of females generally are resistant to inversion effects, while those of males drive systematic sex misperceptions. Implications of the findings are discussed. PMID:25469217
Li, Yangmin
Comparative Analysis for the Inverse Kinematics of Redundant Manipulators based on Repetitive Tracking Tasks Jingguo Wang and Yangmin Li Abstract-- Considering the redundant degree of freedom, joint limit avoidance, objective function, repetitive tracking task I. INTRODUCTION Since it is easy
Xuguang Wang
1999-01-01
In this paper, the computational problem of inverse kinematics of arm prehension movements was investigated. How motions of each joint involved in arm movements can be used to control the end-effector (hand) position and orientation was first examined. It is shown that the inverse kinematics problem due to the kinematic redundancy in joint space is ill-posed only at the control
Li, Yangmin
Inverse Kinematics Analysis for the Arm of A Mobile Humanoid Robot based on the closed kinematics of a seven degrees of freedom (DoF) arm installed on a mobile humanoid robot. Due to the redundancy of 7-DoF open-chain arm, the closed-loop inverse kinematics via pseudoinverse method is used
The Kinematics of the Anthrobot-2 Dextrous Hand
M. S. Ali; Kostas J. Kyriakopoulos; Harry E. Stephanou
1993-01-01
An anthropomorphic dextrous robotic hand (Anthrobot-2) is described. Its forward and inverse kinematics, as well as its Jacobians are developed as the first step toward its utilization for either teleoperation or autonomous operation. The Anthrobot frames are assigned using the modified Denavit-Hartenberg formulation, referred to as the hand frame. A finger with proximal link contact point is described
NASA Astrophysics Data System (ADS)
Pain, S. D.; Bardayan, D. W.; Blackmon, J. C.; Chae, K. Y.; Chipps, K. A.; Cizewski, J. A.; Hatarik, R.; Johnson, M. S.; Jones, K. L.; Kapler, R.; Kozub, R. L.; Livesay, R. J.; Matei, C.; Moazen, B. H.; Nesaraja, C. D.; O'Malley, P.; Smith, M. S.; Swan, T.; Thomas, J. S.; Wilson, G. L.
2008-08-01
The development of high quality radioactive beams has made possible the measurement of transfer reactions in inverse kinematics on unstable nuclei. Measurement of (d,p) reactions on neutron-rich nuclei yield data on the evolution of nuclear structure away from stability, and are of astrophysical interest. Experimentally, (d,p) reactions on heavy (Z=50) fission fragments are complicated by the strongly inverse kinematics, and relatively low beam intensities. Consequently, ejectile detection with high resolution in position and energy, a high dynamic range and a high solid angular coverage is required. The Oak Ridge Rutgers University Barrel Array (ORRUBA) is a new silicon detector array optimized for the measurement of (d,p) reactions in inverse kinematics.
Manipulator inverse kinematics control based on particle swarm optimization neural network
NASA Astrophysics Data System (ADS)
Wen, Xiulan; Sheng, Danghong; Guo, Jing
2008-10-01
The inverse kinematics control of a robotic manipulator requires solving non-linear equations having transcendental functions and involving time-consuming calculations. Particle Swarm Optimization (PSO), which is based on the behaviour of insect swarms and exploits the solution space by taking into account the experience of the single particle as well as that of the entire swarm, is similar to the genetic algorithm (GA) in that it performs a structured randomized search of an unknown parameter space by manipulating a population of parameter estimates to converge on a suitable solution. In this paper, PSO is firstly proposed to optimize feed-forward neural network for manipulator inverse kinematics. Compared with the results of the fast back propagation learning algorithm (FBP), conventional GA genetic algorithm based elitist reservation (EGA), improved GA (IGA) and immune evolutionary computation (IEC), the simulation results verify the particle swarm optimization neural network (PSONN) is effective for manipulator inverse kinematics control.
Pain, S. D. [Rutgers University; Bardayan, Daniel W [ORNL; Blackmon, Jeff C [ORNL; Chae, K. Y. [University of Tennessee, Knoxville (UTK); Chipps, K. [Colorado School of Mines, Golden; Cizewski, J. A. [Rutgers University; Hatarik, Robert [Rutgers University; Johnson, Micah [ORNL; Jones, K. L. [University of Tennessee, Knoxville (UTK); Kapler, R. [University of Tennessee, Knoxville (UTK); Kozub, R. L. [Tennessee Technological University; Livesay, Jake [ORNL; Matei, Catalin [Oak Ridge Associated Universities (ORAU); Moazen, Brian [University of Tennessee, Knoxville (UTK); Nesaraja, Caroline D [ORNL; O'Malley, Patrick [Rutgers University; Smith, Michael Scott [ORNL; Swan, T. P. [University of Surrey, UK; Thomas, J. S. [Rutgers University; Wilson, Gemma L [ORNL
2009-01-01
The development of high quality radioactive beams has made possible the measurement of transfer reactions in inverse kinematics on unstable nuclei. Measurement of (d,p) reactions on neutron-rich nuclei yield data on the evolution of nuclear structure away from stability, and are of astrophysical interest. Experimentally, (d,p) reactions on heavy (Z=50) fission fragments are complicated by the strongly inverse kinematics, and relatively low beam intensities. Consequently, ejectile detection with high resolution in position and energy, a high dynamic range and a high solid angular coverage is required. The Oak Ridge Rutgers University Barrel Array (ORRUBA) is a new silicon detector array optimized for the measurement of (d,p) reactions in inverse kinematics.
A PLANAR PARALLEL MANIPULATOR WITH HOLONOMIC HIGHER PAIRS: INVERSE KINEMATICS
Hayes, John
.g., automatically guided vehicles (AGV) are used indus- trially to convey cargo. The kinematics and dynamics of a three wheeled 2 DOF AGV were studied in great detail in 15]. Robotic mechanical systems involving of the AGV, continuous rolling contact is a by{product of constraints imposed by the operating environment
Kinematic earthquake rupture inversion in the frequency domain
NASA Astrophysics Data System (ADS)
Fan, Wenyuan; Shearer, Peter M.; Gerstoft, Peter
2014-11-01
We develop a frequency-based approach to earthquake slip inversion that requires no prior information on the rupture velocity or slip-rate functions. Because the inversion is linear and is performed separately at each frequency, it is computationally efficient and suited to imaging the finest resolvable spatial details of rupture. We demonstrate the approach on synthetic seismograms based on the Source Inversion Validation Exercise 1 (SIV1) of a crustal Mw 6.6 strike-slip earthquake recorded locally. A robust inversion approach is obtained by applying a combination of damping, smoothing and forcing zero slip at the edge of the fault model. This approach achieves reasonable data fits, overall agreement to the SIV1 model, including slip-rate functions of each subfault, from which its total slip, slip time history and rupture velocity can be extracted. We demonstrate the method's robustness by exploring the effects of noise, random timing errors, and fault geometry errors. The worst effects on the inversion are seen from errors in the assumed fault geometry.
Samy F. M. Assal; Keigo Watanabe; Kiyotaka Izumi
2006-01-01
In this paper, a neural network (NN)-based inverse kinematics problem of redundant manipulators subject to joint limits is presented. The Widrow-Hoff NN with an adaptive learning algorithm derived by applying Lyapunov stability theory is introduced. Since the inverse kinematics has an infinite number of joint angle vectors, a fuzzy neural network (FNN) is designed to provide an approximate value for
INVERSE KINEMATICS AND DYNAMICS ANALYSIS OF A THREE LEGGED PARALLEL MECHANISM ACTUATED BY AGVs
Saha, Subir Kumar
1 INVERSE KINEMATICS AND DYNAMICS ANALYSIS OF A THREE LEGGED PARALLEL MECHANISM ACTUATED BY AGVs mobile robots, or "Automatic Guided Vehicles" (AGVs). Thus, our system consists of a platform by an AGV (Figure 1). Two different configurations are tested: one with ball joints at the upper ends
Vijayakumar, Sethu
D'Souza, A., Vijayakumar, S., Schaal, S., (submitted). Learning inverse kinematics, International Inverse Kinematics Aaron D'Souza adsouza@usc.edu http://wwwslab.usc.edu/adsouza Sethu Vijayakumar sethu computationally e#cient solutions of the inverse kinematics problem. In this con text, this paper investigates
Subramanian, Sriram
An inverse kinematics method for 3D figures with motion data Taku Komura, City Univercity of Hong presents a new inverse kinematics method that utilizes the motion data for realtime control and edit- ing. The key idea is to extract parameters necessary for inverse kinematics from the motion data
NASA Astrophysics Data System (ADS)
Melgar, D.; Bock, Y.
2014-12-01
Rapid kinematic slip inversions immediately following earthquake rupture is traditionally limited to teleseismic data and delayed many hours after large events. Regional data such as strong motion is difficult to incorporate quickly into images of the source process because baseline offsets render the long period portion of the recording unreliable. Recently it's been demonstrated that high rate GPS can potentially produce rapid slip inversions for large events but is limited to very long periods. With an example of the 2011 M9 Tohoku-oki event we will demonstrate that the optimal on-the-fly combination of GPS and strong motion through a seismogeodetic Kalman filter produces reliable, broadband strong motion displacement and velocity waveforms that can be used for kinematic inversion. Through joint inversion of displacement and velocity waveforms we will show that it is possible to obtain a broadband image of the source. Furthermore, we will also show that it is possible to include offshore geophysical observables such as sea surface measurements of tsunami propagation from GPS buoys and ocean bottom pressure sensors into the kinematic inversion. These data better constrain the shallowest part of rupture. We will use the time-dependent deformation of bathymetry predicted from the inversion results as an initial condition for tsunami propagation and inundation modeling. Through a comparison to post-event survey observations we will demonstrate that it is possible to reproduce the inundation pattern along the coastline in great detail and argue that detailed site-specific forecast of tsunami intensity is achievable with current methods and instrumentation.
Neutron Capture Surrogate Reaction on 75As in Inverse Kinematics Using (d,p(gamma))
Peters, W A; Cizewski, J A; Hatarik, R; O?Malley, P D; Jones, K L; Schmitt, K; Moazen, B H; Chae, K Y; Pittman, S T; Kozub, R L; Vieira, D; Jandel, M; Wilhelmy, J B; Matei, C; Escher, J; Bardayan, D W; Pain, S D; Smith, M S
2009-11-09
The {sup 75}As(d,p{gamma}) reaction in inverse kinematics as a surrogate for neutron capture was performed at Oak Ridge National Laboratory using a deuterated plastic target. The intensity of the 165 keV {gamma}-ray from {sup 76}As in coincidence with ejected protons, from exciting {sup 76}As above the neutron separation energy populating a compound state, was measured. A tight geometry of four segmented germanium clover {gamma}-ray detectors together with eight ORRUBA-type silicon-strip charged-particle detectors was used to optimize geometric acceptance. The preliminary analysis of the {sup 75}As experiment, and the efficacy and future plans of the (d,p{gamma}) surrogate campaign in inverse kinematics, are discussed.
Inverse kinematic and forward dynamic models of the 2002 Denali fault earthquake, Alaska
Oglesby, D.D.; Dreger, Douglas S.; Harris, R.A.; Ratchkovski, N.; Hansen, R.
2004-01-01
We perform inverse kinematic and forward dynamic models of the M 7.9 2002 Denali fault, Alaska, earthquake to shed light on the rupture process and dynamics of this event, which took place on a geometrically complex fault system in central Alaska. We use a combination of local seismic and Global Positioning System (GPS) data for our kinematic inversion and find that the slip distribution of this event is characterized by three major asperities on the Denali fault. The rupture nucleated on the Susitna Glacier thrust fault, and after a pause, propagated onto the strike-slip Denali fault. Approximately 216 km to the east, the rupture abandoned the Denali fault in favor of the more southwesterly directed Totschunda fault. Three-dimensional dynamic models of this event indicate that the abandonment of the Denali fault for the Totschunda fault can be explained by the Totschunda fault's more favorable orientation with respect to the local stress field. However, a uniform tectonic stress field cannot explain the complex slip pattern in this event. We also find that our dynamic models predict discontinuous rupture from the Denali to Totschunda fault segments. Such discontinuous rupture helps to qualitatively improve our kinematic inverse models. Two principal implications of our study are (1) a combination of inverse and forward modeling can bring insight into earthquake processes that are not possible with either technique alone, and (2) the stress field on geometrically complex fault systems is most likely not due to a uniform tectonic stress field that is resolved onto fault segments of different orientations; rather, other forms of stress heterogeneity must be invoked to explain the observed slip patterns.
NASA Astrophysics Data System (ADS)
Castro-Artola, O.; Iglesias Mendoza, A.
2012-04-01
Aiming to obtain some information about the rupture process of intermediate to great earthquakes, many waveform inversion schemes have been proposed. Usual methods involve several subfaults on the fault plane to obtain a detailed image of the kinematic rupture process. On the other hand, it has been questioned the resolution over obtained paramters on the inversion process. In the literature contradictory results can be found for the same earthquake, using different schemes. For this reason, recently, simplified schemes of the rupture process have been proposed, while not providing details it can recover their main characteristics. In this work we propose a modification of the Cotton & Campillo (1995) inversion scheme, while unlike considering the problem as a "rupture process tomographic inversion", we invert the main characteristics assuming simplified geometries (ellipses). Based on the work quoted, the direct problem is reparameterized including one or two ellipses in which the maximum displacement is distributed. For the first ellipse, the position of the center within the fault plane, the major and minor semi-axis are inverted. For the second one we invert the position with respect to the first ellipse and the two semi-axis. To avoid the linearization of the problem, we use a simulated annealing scheme for inversion. When there is not enough evidence of the proper fault plane, we perform an inversion for the two nodal planes published to solve the ambiguity between the auxiliary plane and the fault plane that a point source inversion schemes involve. We tested our method for the well studied earthquake September 30th 1999 Oaxaca (Mw=7.5) (e.g. Hernandez et al., 2001) which is one of the intraslab earthquakes within the Northamerican Plate of moderate magnitude and well recorded. The scheme is evaluated as well with the data generated by the "Escenario 2011" framework for an hypothetical earthquake in Guerrero, Mexico. Results will give us the opportunity to evaluate their later routinary implementation to the earthquakes occurring within Mexico.
Study of the 6Li + p 3He + 4He reaction in inverse kinematics
NASA Astrophysics Data System (ADS)
Betsou, Ch.; Pakou, A.; Cappuzzello, F.; Acosta, L.; Agodi, C.; Aslanoglou, X.; Carbone, D.; Cavallaro, M.; Di Pietro, A.; Fernández-García, J. P.; Figuera, P.; Fisichella, M.; Foti, A.; Keeley, N.; Marquinez-Duran, G.; Martel, I.; Mazzocco, M.; Nicolis, N. G.; Pierroutsakou, D.; Rusek, K.; Sgouros, O.; Soukeras, V.; Stiliaris, E.; Strano, E.; Torresi, D.
2015-07-01
Angular distribution measurements were performed for the 6 Li + p 3 He + 4 He reaction in inverse kinematics at incident energies of 2.7, 3.3, 4.2 and 4.8MeV/ u . The detection of both recoils ( 3He and 4He over the laboratory angle range to allowed the determination of the angular distribution over a wide angular range in the center-of-mass frame ( to . The results clarify inconsistencies between existing data sets and are consistent with compound nucleus model calculations.
S-Factor measurement of the 12C(p,?)13N reaction in inverse kinematics
NASA Astrophysics Data System (ADS)
Stöckel, Klaus; Reinhardt, Tobias P.; Akhmadaliev, S.; Bemmerer, D.; Gohl, St.; Reinicke, S.; Schmidt, K.; Serfling, M.; Szücs, T.; Takács, M. P.; Wagner, L.; Zuber, K.
2015-05-01
Hydrogen rich solid targets have been developed and produced to investigate the 12C(p, ?)13N reaction in inverse kinematics. The SRIM simulation software has been used to determine the parameters for ion implantation in various materials. Nuclear Resonant Reacton Analysis (NRRA) with the resonant reaction 15N(p, ??)12C has been carried out to measure the hydrogen content of the produced targets. Measurements of the produced targets at the energy range from Ecm = 577 keV down to Ecm = 191 keV, were performed at the 3-MV Tandetron of Helmholtz-Zentrum Dresden-Rossendorf (HZDR).
Kinematically redundant robot manipulators
NASA Technical Reports Server (NTRS)
Baillieul, J.; Hollerbach, J.; Brockett, R.; Martin, D.; Percy, R.; Thomas, R.
1987-01-01
Research on control, design and programming of kinematically redundant robot manipulators (KRRM) is discussed. These are devices in which there are more joint space degrees of freedom than are required to achieve every position and orientation of the end-effector necessary for a given task in a given workspace. The technological developments described here deal with: kinematic programming techniques for automatically generating joint-space trajectories to execute prescribed tasks; control of redundant manipulators to optimize dynamic criteria (e.g., applications of forces and moments at the end-effector that optimally distribute the loading of actuators); and design of KRRMs to optimize functionality in congested work environments or to achieve other goals unattainable with non-redundant manipulators. Kinematic programming techniques are discussed, which show that some pseudo-inverse techniques that have been proposed for redundant manipulator control fail to achieve the goals of avoiding kinematic singularities and also generating closed joint-space paths corresponding to close paths of the end effector in the workspace. The extended Jacobian is proposed as an alternative to pseudo-inverse techniques.
An inverse kinematics algorithm for a highly redundant variable-geometry-truss manipulator
NASA Technical Reports Server (NTRS)
Naccarato, Frank; Hughes, Peter
1989-01-01
A new class of robotic arm consists of a periodic sequence of truss substructures, each of which has several variable-length members. Such variable-geometry-truss manipulator (VGTMs) are inherently highly redundant and promise a significant increase in dexterity over conventional anthropomorphic manipulators. This dexterity may be exploited for both obstacle avoidance and controlled deployment in complex workspaces. The inverse kinematics problem for such unorthodox manipulators, however, becomes complex because of the large number of degrees of freedom, and conventional solutions to the inverse kinematics problem become inefficient because of the high degree of redundancy. A solution is presented to this problem based on a spline-like reference curve for the manipulator's shape. Such an approach has a number of advantages: (1) direct, intuitive manipulation of shape; (2) reduced calculation time; and (3) direct control over the effective degree of redundancy of the manipulator. Furthermore, although the algorithm was developed primarily for variable-geometry-truss manipulators, it is general enough for application to a number of manipulator designs.
Minor actinide fission induced by multi-nucleon transfer reaction in inverse kinematics
NASA Astrophysics Data System (ADS)
Derkx, X.; Rejmund, F.; Caamaño, M.; Schmidt, K.-H.; Audouin, L.; Bacri, C.-O.; Barreau, G.; Benlliure, J.; Casarejos, E.; Fernández-Domínguez, B.; Gaudefroy, L.; Golabek, C.; Jurado, B.; Lemasson, A.; Navin, A.; Rejmund, M.; Roger, T.; Shrivastava, A.; Schmitt, C.; Taieb, J.
2010-03-01
In the framework of nuclear waste incineration and design of new generation nuclear reactors, experimental data on fission probabilities and on fission fragment yields of minor actinides are crucial to design prototypes. Transfer-induced fission has proven to be an efficient method to study fission probabilities of actinides which cannot be investigated with standard techniques due to their high radioactivity. We report on the preliminary results of an experiment performed at GANIL that investigates fission probabilities with multi-nucleon transfer reactions in inverse kinematics between a 238U beam on a 12C target. Actinides from U to Cm were produced with an excitation energy range from 0 to 30 MeV. In addition, inverse kinematics allowed to characterize the fission fragments in mass and charge. A key point of the analysis resides in the identification of the actinides produced in the different transfer channels. The new annular telescope SPIDER was used to tag the target-like recoil nucleus of the transfer reaction and to determine the excitation energy of the actinide. The fission probability for each transfer channel is accessible and the preliminary results for 238U are promising.
Alpha-particle capture reactions in inverse kinematics relevant to p-process nucleosynthesis
Ujic, P.; Oliveira Santos, F. de; Stodel, Ch.; Saint-Laurent, M.-G.; Kamalou, O.; Amthor, M. A.; Grevy, S.; Caceres, L.; Lagoyannis, A.; Mertzimekis, T. J.; Harissopulos, S.; Demetriou, P.; Perrot, L.; Spyrou, A.
2011-10-28
The first feasibility study of an {alpha}-particle capture reaction in inverse kinematics at energies relevant to the p process was performed at the Wien Filter of the LISE spectrometer at GANIL. Hereby, the {sup 4}He({sup 78}Kr,{gamma}){sup 82}Sr reaction was investigated using as target an {sup 4}He-implanted thin Al foil. The analysis of the data has shown that the determination of ({alpha},{gamma}) reaction cross sections at rather low energies around 2 MeV/u in inverse kinematics is indeed feasible regarding the high rejection rate of the primary beam, which in the present work was better than a factor of 10{sup 9}. However, the expected position of the recoils of interest was completely masked by particles of currently unknown origin that could hardly be attributed to scattering of the primary beam. The most probable explanation for the origin of these 'pollutants' could be microscopic dust particles of 10 {mu}m diameter and less, that are extremely difficult to avoid in standard experimental conditions. Hence, the use of a gas-jet target instead of a solid one is compulsory.
NASA Astrophysics Data System (ADS)
Castaldo, R.; Tizzani, P.; Lollino, P.; Calò, F.; Ardizzone, F.; Lanari, R.; Guzzetti, F.; Manunta, M.
2014-12-01
The aim of this paper is to propose a methodology to perform inverse numerical modelling of slow landslides that combines the potentialities of both numerical approaches and well-known remote-sensing satellite techniques. In particular, through an optimization procedure based on a genetic algorithm, we minimize, with respect to a proper penalty function, the difference between the modelled displacement field and differential synthetic aperture radar interferometry (DInSAR) deformation time series. The proposed methodology allows us to automatically search for the physical parameters that characterize the landslide behaviour. To validate the presented approach, we focus our analysis on the slow Ivancich landslide (Assisi, central Italy). The kinematical evolution of the unstable slope is investigated via long-term DInSAR analysis, by exploiting about 20 years of ERS-1/2 and ENVISAT satellite acquisitions. The landslide is driven by the presence of a shear band, whose behaviour is simulated through a two-dimensional time-dependent finite element model, in two different physical scenarios, i.e. Newtonian viscous flow and a deviatoric creep model. Comparison between the model results and DInSAR measurements reveals that the deviatoric creep model is more suitable to describe the kinematical evolution of the landslide. This finding is also confirmed by comparing the model results with the available independent inclinometer measurements. Our analysis emphasizes that integration of different data, within inverse numerical models, allows deep investigation of the kinematical behaviour of slow active landslides and discrimination of the driving forces that govern their deformation processes.
NASA Astrophysics Data System (ADS)
Xu, Wenfu; She, Yu; Xu, Yangsheng
2014-12-01
Redundant space manipulators, including Space Station Remote Manipulator System (SSRMS), Special Purpose Dexterous Manipulator (SPDM) and European Robotic Arm (ERA), have been playing important roles in the construction and maintenance of International Space Station (ISS). They all have 7 revolute joints arranged in similar configurations, and are referred to as SSRMS-type manipulators. When a joint is locked in an arbitrary position due to some failures, a 7R manipulator degrades to a 6R manipulator. Without a spherical wrist or three consecutive parallel joints, the inverse kinematics of the 6R manipulator is very complex. In this paper, we propose effective methods to resolve the inverse kinematics for different cases of any joint locked in an arbitrary position. Firstly, configuration characteristics of the SSRMS-type redundant manipulators are analyzed. Then, an existing of closed-form inverse kinematics is discussed for locking different joints. Secondly, D-H frames and corresponding D-H parameters of the new 6-DOF manipulator formed by locking a joint in an arbitrary position are re-constructed. A unified table is then created to describe the kinematics for all possible cases of single joint locking failure. Thirdly, completely analytical and semi-analytical methods are presented to solve the inverse kinematics equations, and the former is used for locking joint 1, 2, 6 or 7 while the latter for locking joint 3, 4 or 5. Finally, typical cases for single joint locking are studied. The results verify the proposed methods.
Development of a new Recoil Distance Technique using Coulomb Excitation in Inverse Kinematics
Rother, Wolfram; Dewald, Alfred; Ilie, Gabriela; Pissulla, Thomas; Melon, Barbara; Jolie, Jan; Pascovici, Gheorghe; Iwasaki, Hironori; Hackstein, Matthias; Zell, Karl-Oskar; Julin, Rauno; Jones, Peter; Greenlees, Paul; Rahkila, Panu; Uusitalo, Juha; Scholey, Cath; Harissopulos, Sotirios; Lagoyannis, Anastasios; Konstantinopoulos, Theodore; Grahn, Tuomas
2009-01-28
We report on an experiment using Coulomb excitation in inverse kinematics in combination with the plunger technique for measuring lifetimes of excited states of the projectiles. Aside from the investigation of E(5) features in {sup 128}Xe, the aim was to explore the special features of such experiments which are also suited to be used with radioactive beams. The measurement was performed at the JYFL with the Koeln coincidence plunger device and the JUROGAM spectrometer using a {sup 128}Xe beam impinging on a {sup nat}Fe target at a beam energy of 525 MeV. Recoils were detected by means of 32 solar cells placed at extreme forward angles. Particle-gated {gamma}-singles and {gamma}{gamma}-coincidences were measured at different target-degrader distances. Details of the experiment and first results are presented.
14Be(p,n)14B reaction at 69 MeV in inverse kinematics
Y. Satou; T. Nakamura; Y. Kondo; N. Matsui; Y. Hashimoto; T. Nakabayashi; T. Okumura; M. Shinohara; N. Fukuda; T. Sugimoto; H. Otsu; Y. Togano; T. Motobayashi; H. Sakurai; Y. Yanagisawa; N. Aoi; S. Takeuchi; T. Gomi; M. Ishihara; S. Kawai; H. J. Ong; T. K. Onishi; S. Shimoura; M. Tamaki; T. Kobayashi; Y. Matsuda; N. Endo; M. Kitayama
2011-03-03
A Gamow-Teller (GT) transition from the drip-line nucleus 14Be to 14B was studied via the (p,n) reaction in inverse kinematics using a secondary 14Be beam at 69 MeV/nucleon. The invariant mass method is employed to reconstruct the energy spectrum. A peak is observed at an excitation energy of 1.27(2) MeV in 14B, together with bumps at 2.08 and 4.06(5) MeV. The observed forward peaking of the state at 1.27 MeV and a good description for the differential cross section, obtained with a DWBA calculation provide support for the 1+ assignment to this state. By extrapolating the cross section to zero momentum transfer the GT-transition strength is deduced. The value is found to compare well with that reported in a beta-delayed neutron emission study.
Spectroscopy of Low-Lying Proton-Resonances using the (d , n) Reaction in Inverse Kinematics
NASA Astrophysics Data System (ADS)
Wiedenhoever, Ingo; Baby, Lagy T.; Kuvin, Sean; Baker, Jessica; Blackmon, Jeff; Deibel, Catherine; Macon, Kevin; Gay, Dennis; Colbert, Kayla; Quails, Nathan; Florida State University Team; Louisiana State University Team; University of North Florida Team
2014-09-01
Studies of rp-process nucleosynthesis in stellar explosions show that establishing the lowest l = 0 and l = 1 resonances is the most important step to determine reaction rates in the astrophysical rp -process path. In order to establish the (d , n) reaction as a standard technique for the spectroscopy of astrophysical resonances, we have developed a compact setup of low-energy Neutron-detectors, resoneut and tested it with the stable beam reaction 12 C(d , n) 13 N in inverse kinematics. At the resolut in-flight radioactive beam facility, we have used the new detector system to investigate the l = 0 and l = 1 resonance spectrum in 18Ne and 26Si. Results from these experiments and the implications on proton-induced nucleosynthesis rates will be discussed. Studies of rp-process nucleosynthesis in stellar explosions show that establishing the lowest l = 0 and l = 1 resonances is the most important step to determine reaction rates in the astrophysical rp -process path. In order to establish the (d , n) reaction as a standard technique for the spectroscopy of astrophysical resonances, we have developed a compact setup of low-energy Neutron-detectors, resoneut and tested it with the stable beam reaction 12 C(d , n) 13 N in inverse kinematics. At the resolut in-flight radioactive beam facility, we have used the new detector system to investigate the l = 0 and l = 1 resonance spectrum in 18Ne and 26Si. Results from these experiments and the implications on proton-induced nucleosynthesis rates will be discussed. Supported by NSF under grants PHY-1064819, PHY-0821308 and PHY-0820941. Supported by DOE under grant DE-FG02-02ER41220.
NASA Technical Reports Server (NTRS)
Fielding, Eric; Sladen, Anthony; Avouac, Jean-Philippe; Li, Zhenhong; Ryder, Isabelle; Burgmann, Roland
2008-01-01
The presentations explores kinematics of the Wenchaun-Beichuan earthquake using data from ALOS, Envisat, and teleseismic recordings. Topics include geomorphic mapping, ALOS PALSAR range offsets, ALOS PALSAR interferometry, Envisat IM interferometry, Envisat ScanSAR, Joint GPS-InSAR inversion, and joint GPS-teleseismic inversion (static and kinematic).
Kurapov, Alexander
Unfolding: An inverse approach to fold kinematics Jaume Verge´ s Departament de Geologia Dina` mica Meigs ABSTRACT Preserved fold shapes usually reveal little about their kinematic evolution. Syntectonic to an initial undeformed state. Such reconstructions can define the kinematics of fold growth. Growth strata
Kinematic deprojection and mass inversion of spherical systems of known velocity anisotropy
NASA Astrophysics Data System (ADS)
Mamon, Gary A.; Boué, Gwenaël
2010-02-01
Traditionally, the degeneracy between the unknown radial profiles of total mass and velocity anisotropy inherent in the spherical, stationary, non-streaming Jeans equation has been handled by assuming a mass profile and fitting models to the observed kinematical data. However, mass profiles are still not well known: there are discrepancies in the inner slopes of the density profiles of haloes found in dissipationless cosmological N-body simulations, and the inclusion of gas alters significantly the inner slopes of both the total mass and the dark matter component. Here, the opposite approach is considered: the equation of anisotropic kinematic projection is inverted for known arbitrary anisotropy to yield the space radial velocity dispersion profile in terms of an integral involving the radial profiles of anisotropy and isotropic dynamical pressure (itself a single integral of observable quantities). Then, through the Jeans equation, the mass profile of a spherical system is derived in terms of double integrals of observable quantities. Single integral formulas for both deprojection and mass inversion are provided for several simple anisotropy models (isotropic, radial, circular, general constant, Osipkov-Merritt, Mamon-?okas and Diemand-Moore-Stadel). Tests of the mass inversion on Navarro, Frenk and White (NFW) models with the first four of these anisotropy models yield accurate results in the case of perfect observational data, and typically better than 70 per cent (in four cases out of five) accurate mass profiles for the sampling errors expected from current observational data on clusters of galaxies. For the NFW model with mildly increasing radial anisotropy, the mass is found to be insensitive to the adopted anisotropy profile at 7 scale radii and to the adopted anisotropy radius at 3 scale radii. This anisotropic mass inversion method is a useful complementary tool to analyse the mass and anisotropy profiles of spherical systems. It provides the practical means to lift the mass-anisotropy degeneracy in quasi-spherical systems such as globular clusters, round dwarf spheroidal and elliptical galaxies, as well as groups and clusters of galaxies, when the anisotropy of the tracer is expected to be linearly related to the slope of its density.
Kinematic Source Inversion using Strong Motion Data Considering Three-Dimensional Fault Geometry
NASA Astrophysics Data System (ADS)
Asano, K.; Iwata, T.
2009-12-01
Near-source strong ground motion during large earthquake is governed by spatiotemporal slip progression on the fault plane. Many previous studies succeeded to obtain precise slip distributions of large earthquakes from strong motion and other seismic and geodetic data. The geometry of source fault is also known to be important to quantitatively explain near-source strong ground motions as seen in the case for the 1999 Chi-Chi earthquake (e.g., Iwata and Sekiguchi, 2000). However, most of source inversion studies except special cases assumed one or plural planar fault planes in their kinematic inversion analyses. In order to include effects of fault geometry on near-source ground motions, we are trying to develop a method to invert slip distribution with its fault geometry. The proposed method is applied to the 2008 Iwate-Miyagi Nairiku earthquake, which is a MW6.9 inland crustal earthquake occurring in northeast Japan in last June. In this test case, depth-dependency of dip angle is considered. We have already obtained the slip distribution of this event assuming a planer fault model (Asano and Iwata, AGU 2008FM). In the first step, a linear source inversion (e.g., Hartzell and Heaton, 1983) is carried out assuming a planar fault model, which follows the focal mechanism solution distributed in the F-net MT catalog. That is, all the subfaults have same strike and dip angles same as in conventional source inversions. In the second step, the fault geometry is represented by dip angles at some control points on the fault. The dip angle at each subfault is set by bilinear interpolation. Then, dip angles at control points and slip amounts at each subfaults are iteratively solved from the same data set using the solution from the first step as the initial model. The preliminary result shows that the estimated fault geometry prefers to have lower dip angle at shallower portion and higher dip angles at deeper portion. These features are consistent to the precise aftershock distribution of this event. We will improve the method to obtain a stable solution, and the proposed method can be easily extended to include strike variations along the source fault. Acknowledgements: Strong motion data from K-NET, KiK-net and Aratozawa Dam are used in this study.
Unseren, M.A.
1993-04-01
The report discusses the orientation tracking control problem for a kinematically redundant, autonomous manipulator moving in a three dimensional workspace. The orientation error is derived using the normalized quaternion error method of Ickes, the Luh, Walker, and Paul error method, and a method suggested here utilizing the Rodrigues parameters, all of which are expressed in terms of normalized quaternions. The analytical time derivatives of the orientation errors are determined. The latter, along with the translational velocity error, form a dosed loop kinematic velocity model of the manipulator using normalized quaternion and translational position feedback. An analysis of the singularities associated with expressing the models in a form suitable for solving the inverse kinematics problem is given. Two redundancy resolution algorithms originally developed using an open loop kinematic velocity model of the manipulator are extended to properly take into account the orientation tracking control problem. This report furnishes the necessary mathematical framework required prior to experimental implementation of the orientation tracking control schemes on the seven axis CESARm research manipulator or on the seven-axis Robotics Research K1207i dexterous manipulator, the latter of which is to be delivered to the Oak Ridge National Laboratory in 1993.
Measurement of the ^134Te(d,p)^135Te Reaction in Inverse Kinematics
NASA Astrophysics Data System (ADS)
Pain, Steven
2007-10-01
The development of high quality radioactive beams, such as those at the HRIBF at ORNL, has made possible the performance of transfer reactions on unstable nuclei. Measurements of (d,p) reactions on n-rich fission fragments yield data on nuclear structure away from stability, and are of astrophysical interest due to the proximity to suggested r- process paths. The energies and spectroscopic information of single-particle states near to shell closures are of particular importance, since they provide both an important constraint on nuclear structure models and are directly relevant to direct neutron-capture cross sections. The single-neutron states in ^ 135Te, one neutron beyond the N=82 shell closure, are of particular interest, both for r-process nucleosynthesis and its relevance to an isotopic anomaly of Xe found in pre-solar meteoritic grains. The ^134Te(d,p)^135Te reaction has been measured in inverse kinematics at the HRIBF utilizing a beam of ^134Te at 643 MeV and a deuterated plastic target. Proton ejectiles were detected forward and backwards of ?lab = 90^o using an early implementation of the Oak Ridge Rutgers University Barrel Array (ORRUBA) in conjunction with SIDAR. Details of the experiment and the current stage of the data analysis will be presented.
NASA Astrophysics Data System (ADS)
Reifarth, René; Litvinov, Yuri A.; Endres, Anne; Göbel, Kathrin; Heftrich, Tanja; Glorius, Jan; Koloczek, Alexander; Sonnabend, Kerstin; Travaglio, Claudia; Weigand, Mario
2015-05-01
Neutron capture cross sections of unstable isotopes are important for neutron-induced nucleosynthesis as well as for technological applications. A combination of a radioactive beam facility, an ion storage ring and a high flux reactor would allow a direct measurement of neutron induced reactions over a wide energy range on isotopes with half lives down to minutes. The idea is to measure neutron-induced reactions on radioactive ions in inverse kinematics. This means, the radioactive ions will pass through a neutron target. In order to efficiently use the rare nuclides as well as to enhance the luminosity, the exotic nuclides can be stored in an ion storage ring. The neutron target can be the core of a research reactor, where one of the central fuel elements is replaced by the evacuated beam pipe of the storage ring. Using particle detectors and Schottky spectroscopy, most of the important neutron-induced reactions, such as (n,?), (n,p), (n,?), (n,2n), or (n,f), could be investigated.
Reifarth, René; Endres, Anne; Göbel, Kathrin; Heftrich, Tanja; Glorius, Jan; Koloczek, Alexander; Sonnabend, Kerstin; Travaglio, Claudia; Weigand, Mario
2015-01-01
Neutron capture cross sections of unstable isotopes are important for neutron-induced nucleosynthesis as well as for technological applications. A combination of a radioactive beam facility, an ion storage ring and a high flux reactor would allow a direct measurement of neutron induced reactions over a wide energy range on isotopes with half lives down to minutes. The idea is to measure neutron-induced reactions on radioactive ions in inverse kinematics. This means, the radioactive ions will pass through a neutron target. In order to efficiently use the rare nuclides as well as to enhance the luminosity, the exotic nuclides can be stored in an ion storage ring. The neutron target can be the core of a research reactor, where one of the central fuel elements is replaced by the evacuated beam pipe of the storage ring. Using particle detectors and Schottky spectroscopy, most of the important neutron-induced reactions, such as (n,$\\gamma$), (n,p), (n,$\\alpha$), (n,2n), or (n,f), could be investigated.
NASA Technical Reports Server (NTRS)
Williams, Robert L., III
1992-01-01
This paper presents three methods to solve the inverse position kinematics position problem of the double universal joint attached to a manipulator: (1) an analytical solution for two specific cases; (2) an approximate closed form solution based on ignoring the wrist offset; and (3) an iterative method which repeats closed form position and orientation calculations until the solution is achieved. Several manipulators are used to demonstrate the solution methods: cartesian, cylindrical, spherical, and an anthropomorphic articulated arm, based on the Flight Telerobotic Servicer (FTS) arm. A singularity analysis is presented for the double universal joint wrist attached to the above manipulator arms. While the double universal joint wrist standing alone is singularity-free in orientation, the singularity analysis indicates the presence of coupled position/orientation singularities of the spherical and articulated manipulators with the wrist. The cartesian and cylindrical manipulators with the double universal joint wrist were found to be singularity-free. The methods of this paper can be implemented in a real-time controller for manipulators with the double universal joint wrist. Such mechanically dextrous systems could be used in telerobotic and industrial applications, but further work is required to avoid the singularities.
Direct measurement of 38K(p , ?) 39Ca in inverse kinematics
NASA Astrophysics Data System (ADS)
Lotay, Gavin; Christian, Gregory; Burke, Devin; Chen, Alan; Connolly, Devin; Davids, Barry; Fallis, Jenniffer; Hager, Ulrike; Hutcheon, Dave; Mahl, Adam; Rojas, Alex; Ruiz, Chris; Sun, Xuan
2014-09-01
Sensitivity studies have identified 38K(p , ?) 39Ca as one of a handful of significant reactions in ONe novae, with the potential to change 38Ar, 39K, and 40Ca abundances in ONe ejecta by factors of ~18, ~17 and ~24, respectively. We have performed the first ever measurement of this reaction using the DRAGON recoil mass separator at TRIUMF. The experiment was performed in inverse kinematics using a beam of radioactive 38K. To date, this is the most massive projectile ever used in a radiative capture experiment. The astrophysical reaction rate is expected to be dominated by low- l resonances inside the Gamow window. Hence we have focused our efforts on the resonances at Ec.m. = 386, 515, and 689 keV. In this talk, I will present an overview of the experiment and data analysis and show preliminary resonance strengths (or upper limits) measured at each of the three energies. Finally, I will discuss the astrophysical implications of the measurements as they relate to ONe novae.
Study of 13B(d,p)14B Reaction in Inverse Kinematics with Helios
NASA Astrophysics Data System (ADS)
Bedoor, S.; Wuosmaa, A. H.; Lighthall, J. C.; Marley, S. T.; Shetty, D. V.; Alcorta, M.; Back, B. B.; Bertone, P. F.; Rehm, K. E.; Rogers, A. M.; Schiffer, J. P.; Brown, B. A.; Deibel, C. M.
2012-10-01
The ^14B nucleus was studied employing the (d, p) reaction in inverse kinematics using HELIOS at the ATLAS facility at ANL. A beam of ^13B with energy 15.7 MeV/nucleon was produced using the In-Flight method. Protons from the ^13B(d, p)^14B reaction were detected and analyzed using the HELIOS device. Detecting and identifying the recoiling ^13B and ^14B nuclei in a silicon ?E-E telescope at forward angles distinguished bound and unbound states in ^14B. Angular-momentum transfers and relative spectroscopic factors were deduced for the four lowest states in ^14B. The ground and first excited states, 2^- and 1^- respectively, are presumably made up of ?(0p3/2)-?(1s1/2) configurations, while coupling of the proton hole to a d5/2 neutron produces (1,2,3,4)^-. The 0d5/2-1s1/2 splitting in ^14B is expected to be small, producing mixing between the (1,2)^- l = 0 and 2 configurations. The measured spectroscopic factors for neutron transfer will be compared to the predictions of the shell model calculations.
Study of the 19O(d , p) reaction in inverse kinematics with HELIOS
NASA Astrophysics Data System (ADS)
Hoffman, C. R.; Alcorta, M.; Back, B. B.; Baker, S. I.; Bertone, P. F.; Clark, J. A.; Digiovine, B.; Kay, B. P.; Pardo, R. C.; Rehm, K. E.; Schiffer, J. P.; Deibel, C. M.; Marley, S. T.; Lighthall, J. C.; Bedoor, S.; Shetty, D. V.; Wuosmaa, A. H.; Freeman, S. J.; Sharp, D. K.; Thomas, J. S.; Rojas, A.; Santiago-Gonzalez, D.; Wiedenhöver, I.
2011-10-01
The neutron single-particle components of states in 20O have been probed through the (d, p) reaction in inverse kinematics. The experiment consisted of a 125 MeV radioactive 19O beam, produced by the ATLAS In-Flight facility at Argonne National Laboratory, impinging on a [(C2D4)n] target located inside the HELIcal Orbit Spectrometer (HELIOS). A Q-value resolution of ~150 KeV was achieved for states in 20O. Absolute cross sections and angular distributions have been determined for a number of levels in 20O up to 7 MeV in excitation energy. A strong candidate for the previously unobserved l = 0 3+ level at 5.2 MeV has been identified. The extracted spectroscopic factors for l = 2 (presumably ? 0d5 / 2) and l = 0 (? 1s1 / 2) transitions will be compared to those along the Z = 8 isotopic chain and to microscopic calculations. Support from US DOE Contract No. DE-AC02-06CH11357 and No. DE-FG-2-04ER41320, NSF Grant No. PHY-08022648, and the UK STFC.
Results from (d,p) measurements in inverse kinematics at the HRIBF
NASA Astrophysics Data System (ADS)
Jones, K. L.; Kozub, R. L.
2006-10-01
The Center of Excellence for Radioactive Ion Beam Studies has begun a program of (d,p) transfer experiments on fission fragment beams. These types of measurements probe the structure of nuclei away from stability, providing critical information for neutron-capture network models. The doubly-magic nuclei are used as bench marks for structure models. However, few exotic doubly-magic nuclei are available for in depth study, such as can be made using transfer reactions. Understanding the evolution of single-particle structure of nuclei close to the magic numbers, but away from the valley of stability, is crucial for improving models of the nucleus. This, in turn, provides critical information for neutron-capture network models. Fission fragment beams in the 132Sn region are available at Coulomb barrier energies at the Holifield Radioactive Ion Beam Facility (HRIBF). A major focus of our studies is on nuclei around the doubly-magic 132Sn nucleus. We have made a proof of principle study of (d,p) reactions in inverse kinematics in the A˜132 region using a stable beam of 124Sn [1]. Results from the test measurement and the status of two experiments using radioactive 130Sn and 132Sn beams will be presented. [1] K.L. Jones et al., Phys. Rev. C 70, 067602 (2004).
Design of human-like posture prediction for inverse kinematic posture control of a humanoid robot
Thomann, Derik (Derik S.)
2005-01-01
A method and system has been developed to solve the kinematic redundancy for a humanoid redundant manipulator based on forward kinematic equation and the optimization of human-like constraints. The Multiple Objective ...
A. De Santis; B. Siciliano; L. Villani
2008-01-01
In this paper a fuzzy logic approach to automatic trajectory planning and closed-loop inverse kinematics for a robotic system\\u000a purposely designed to extinguish fires in road and railway tunnels is presented. The robot is composed of a self-cooling monorail\\u000a vehicle carrying a fire fighting monitor. A fuzzy inference system is adopted for the automatic generation of the task-space\\u000a trajectory for
NASA Astrophysics Data System (ADS)
Pain, S. D.; Cizewski, J. A.; Hatarik, R.; Jones, K. L.; Thomas, J. S.; Bardayan, D. W.; Blackmon, J. C.; Nesaraja, C. D.; Smith, M. S.; Kozub, R. L.; Johnson, M. S.
2007-08-01
The development of high quality radioactive beams, such as those at the HRIBF at Oak Ridge National Laboratory, has made possible the measurement of transfer reactions in inverse kinematics on unstable nuclei. Measurement of (d,p) reactions on neutron-rich nuclei yield data on the evolution of nuclear structure away from stability, and are of astrophysical interest due to the proximity of suggested nuclear burning paths in the astrophysical r-process in supernovae. Experimentally, (d,p) reactions on heavy (Z = 50) fission fragments are complicated by the strongly inverse kinematics, and the relatively low beam intensities. Consequently, ejectile detection with high resolution in position and energy, a high dynamic range and a high solid angular coverage is required. The Oak Ridge Rutgers University Barrel Array (ORRUBA) is a new silicon detector array currently under construction, optimized for the measurement of (d,p) reactions in inverse kinematics. It consists of two rings of silicon detectors, providing a high solid angular coverage for angles symmetrically forward and backward of 90°. Resistive strip detectors are used to obtain high precision position and energy measurement of reaction ejectiles.
NASA Astrophysics Data System (ADS)
Goldberg, D.; Haase, J. S.; Melgar, D.; Bock, Y.; Geng, J.; Saunders, J. K.
2014-12-01
The seismogeodetic combination of high-rate GPS observables and seismic acceleration captures the broadband on-scale recording of earthquake ground motions. The use of these data for determining rapid centroid moment tensor solutions ("fastCMT") has been demonstrated in the post-analysis of the 2010 Mw 7.2 El Mayor-Cucapah earthquake. This seismogeodetic combination will improve source inversions for future earthquakes, but large-scale accelerometer deployment at the many available permanent GPS stations is limited by the cost of traditional observatory-grade accelerometers. Instead, we improve feasibility by installing SIO Geodetic Modules and low-cost MEMS accelerometers at 17 GPS stations in southern California near the San Andreas, San Jacinto, and Elsinore faults, transmitting data in real time for analysis of seismic velocity and displacement waveforms. We examine the performance of our seismogeodetic subnetwork using the El Mayor-Cucapah earthquake as our focus. We calculate a kinematic slip inversion, using the small set of seismogeodetic waveforms available at the time of the event, and assess the reliability of the result in comparison to the fastCMT solution. We evaluate reliability by using our model to predict ground motion at independent stations, and using recorded data as verification at a range of frequencies. Next we supplement the dataset by including realistic simulated waveforms for the additional 17 seismogeodetic stations, adding realistic seismogeodetic noise, and demonstrate the improved reliability of our result in terms of reducing the space of possible solutions due to better geometric constraints. The MEMS accelerometer has higher noise than the observatory-grade accelerometer, which we quantify using strong motion recordings from a series of UCSD NEES outdoor shaketable experiments conducted in December 2013 and January 2014. Results will provide confidence in the use of the MEMS accelerometer for large-scale deployment as an alternative to an observatory-grade accelerometer, as well as the prospects for the increased station density to improve the source parameters of future events, in particular a large earthquake forecast for the southern San Andreas fault.
NASA Astrophysics Data System (ADS)
Rollins, Christopher; Barbot, Sylvain; Avouac, Jean-Philippe
2015-05-01
Due to its location on a transtensional section of the Pacific-North American plate boundary, the Salton Trough is a region featuring large strike-slip earthquakes within a regime of shallow asthenosphere, high heat flow, and complex faulting, and so postseismic deformation there may feature enhanced viscoelastic relaxation and afterslip that is particularly detectable at the surface. The 2010 El Mayor-Cucapah earthquake was the largest shock in the Salton Trough since 1892 and occurred close to the US-Mexico border, and so the postseismic deformation recorded by the continuous GPS network of southern California provides an opportunity to study the rheology of this region. Three-year postseismic transients extracted from GPS displacement time-series show four key features: (1) 1-2 cm of cumulative uplift in the Imperial Valley and 1 cm of subsidence in the Peninsular Ranges, (2) relatively large cumulative horizontal displacements 150 km from the rupture in the Peninsular Ranges, (3) rapidly decaying horizontal displacement rates in the first few months after the earthquake in the Imperial Valley, and (4) sustained horizontal velocities, following the rapid early motions, that were still visibly ongoing 3 years after the earthquake. Kinematic inversions show that the cumulative 3-year postseismic displacement field can be well fit by afterslip on and below the coseismic rupture, though these solutions require afterslip with a total moment equivalent to at least a earthquake and higher slip magnitudes than those predicted by coseismic stress changes. Forward modeling shows that stress-driven afterslip and viscoelastic relaxation in various configurations within the lithosphere can reproduce the early and later horizontal velocities in the Imperial Valley, while Newtonian viscoelastic relaxation in the asthenosphere can reproduce the uplift in the Imperial Valley and the subsidence and large westward displacements in the Peninsular Ranges. We present two forward models of dynamically coupled deformation mechanisms that fit the postseismic transient well: a model combining afterslip in the lower crust, Newtonian viscoelastic relaxation in a localized zone in the lower crust beneath areas of high heat flow and geothermal activity, and Newtonian viscoelastic relaxation in the asthenosphere; and a second model that replaces the afterslip in the first model with viscoelastic relaxation with a stress-dependent viscosity in the mantle. The rheology of this high-heat-flow, high-strain-rate region may incorporate elements of both these models and may well be more complex than either of them.
Computational Development of Jacobian Matrices for Complex Spatial Manipulators.
Goehler, Craig M; Murray, Wendy M
2012-05-01
Current methods for developing manipulator Jacobian matrices are based on traditional kinematic descriptions such as Denavit and Hartenberg parameters. The resulting symbolic equations for these matrices become cumbersome and computationally inefficient when dealing with more complex spatial manipulators, such as those seen in the field of biomechanics. This paper develops a modified method for Jacobian development based on generalized kinematic equations that incorporates partial derivatives of matrices with Leibniz's Law (the product rule). It is shown that a set of symbolic matrix functions can be derived that improve computational efficiency when used in MATLAB(®) M-Files and are applicable to any spatial manipulator. An articulated arm subassembly and a musculoskeletal model of the hand are used as examples. PMID:22442500
NASA Astrophysics Data System (ADS)
Pain, S. D.; Bardayan, D. W.; Blackmon, J. C.; Carter, H. K.; Cizewski, J. A.; Domizioli, C.; Erikson, L.; Harlin, C.; Johnson, M. S.; Jones, K. L.; Kozub, R.; Moazen, B. H.; Nesaraja, C. D.; Smith, M. S.; Thomas, J. S.; Visser, D.
2004-11-01
The development of radioactive beams with high quality beam profiles, such as those available at the HRIBF at Oak Ridge National Laboratory, has made the perform transfer reactions in inverse kinematics on unstable nuclei possible. Such measurements on neutron-rich nuclei yield data on the development of nuclear structure away from stability, and are of specific astrophysical interest due to the proximity to the r-process path. With the relatively low intensities currently obtainable with radioactive beams (compared to stable beam intensities), high detection efficiencies are required to make such experiments statistically feasible. The Oak Ridge Rutgers University Barrel Array (ORRUBA) is a new silicon detector array designed for measurements of transfer reactions in inverse kinematics, consisting of two rings of silicon detector telescopes. These provide high solid angular coverage for angles symmetrically forward and backward of ? = 90^rc. Each telescope consists of a thin transmission detector, and a thick stopping detector, and each detector is divided into four resistive strips, providing position information. Such an arrangement enables particle identification, determination of the emission angles of the detected particles and measurement of their energies. The array is currently in its construction phase. An outline of the arrays scientific motivation and technical aspects will be presented. *This work was supported in part by the U.S. Department of Energy
NASA Astrophysics Data System (ADS)
Barki, Anum; Kendricks, Kimberly; Tuttle, Ronald F.; Bunker, David J.; Borel, Christoph C.
2013-05-01
This research highlights the results obtained from applying the method of inverse kinematics, using Groebner basis theory, to the human gait cycle to extract and identify lower extremity gait signatures. The increased threat from suicide bombers and the force protection issues of today have motivated a team at Air Force Institute of Technology (AFIT) to research pattern recognition in the human gait cycle. The purpose of this research is to identify gait signatures of human subjects and distinguish between subjects carrying a load to those subjects without a load. These signatures were investigated via a model of the lower extremities based on motion capture observations, in particular, foot placement and the joint angles for subjects affected by carrying extra load on the body. The human gait cycle was captured and analyzed using a developed toolkit consisting of an inverse kinematic motion model of the lower extremity and a graphical user interface. Hip, knee, and ankle angles were analyzed to identify gait angle variance and range of motion. Female subjects exhibited the most knee angle variance and produced a proportional correlation between knee flexion and load carriage.
Geometry and kinematics of Late Cretaceous inversion structures in the Jiuquan Basin, western China
Wang, B.; Chen, H.; Yang, S.; Xiao, A.; Cheng, X.; Rupp, J.A.
2005-01-01
Late Cretaceous inversion structures, which are significant for oil and gas accumulation, are widely distributed throughout the Jiuquan Basin. These structures are primarily made up of inverted faults and fault-related folds. Most of the axial planes of folds are parallel to inverted faults trending north-east, indicating that the principal stress direction was north-west - south-east in the Late Cretaceous. The average inversion ratios of faults in the four sags that were investigated are 0.39, 0.29, 0.38, 0.32. The average inversion ratio in the Jiuquan Basin is 0.34 and the degree of inversion is moderate to strong. As moderate inversion is suitable for forming excellent hydrocarbon traps, there is considered to be significant potential in the basin for the presence of structural traps. ?? 2005 Elsevier Ltd. All rights reserved.
3D Motion Planning Algorithms for Steerable Needles Using Inverse Kinematics
Alterovitz, Ron
be interpreted as an airplane with constant speed and pitch rate, zero yaw, and controllable roll angle. We) Steerable needle. r (b) Equivalent airplane. r x y z v n (c) Coordinate setup. Fig. 1. Model setup of a steerable needle and a kinematically equivalent airplane with fixed speed and pitch rate, zero yaw
A new approach to solve inverse kinematics of a planar flexible continuum robot
NASA Astrophysics Data System (ADS)
Amouri, Ammar; Mahfoudi, Chawki; Zaatri, Abdelouahab; Merabti, Halim
2014-10-01
Research on the modeling of continuum robots, focused on ways to constrain the geometrical models, while maintaining maximum specificities and mechanical properties of the robot. In this paper we propose a new numerical solution for solving the inverse geometric model of a planar flexible continuum robot, we assuming that each section is curved in an arc of a circle, while having the central axis of the inextensible structure. The inverse geometric model for one section is calculated geometrically, whereas the extreme points, of each section, used in calculating the inverse geometric model for multi-section is calculated numerically using a particle swarm optimization (PSO) method. Simulation examples of this method are carried to validate the proposed approach.
NASA Technical Reports Server (NTRS)
Williams, Robert L., II
1992-01-01
The forward position and velocity kinematics for the redundant eight-degree-of-freedom Advanced Research Manipulator 2 (ARM2) are presented. Inverse position and velocity kinematic solutions are also presented. The approach in this paper is to specify two of the unknowns and solve for the remaining six unknowns. Two unknowns can be specified with two restrictions. First, the elbow joint angle and rate cannot be specified because they are known from the end-effector position and velocity. Second, one unknown must be specified from the four-jointed wrist, and the second from joints that translate the wrist, elbow joint excluded. There are eight solutions to the inverse position problem. The inverse velocity solution is unique, assuming the Jacobian matrix is not singular. A discussion of singularities is based on specifying two joint rates and analyzing the reduced Jacobian matrix. When this matrix is singular, the generalized inverse may be used as an alternate solution. Computer simulations were developed to verify the equations. Examples demonstrate agreement between forward and inverse solutions.
Kinematics of an in-parallel actuated manipulator based on the Stewart platform mechanism
NASA Technical Reports Server (NTRS)
Williams, Robert L., II
1992-01-01
This paper presents kinematic equations and solutions for an in-parallel actuated robotic mechanism based on Stewart's platform. These equations are required for inverse position and resolved rate (inverse velocity) platform control. NASA LaRC has a Vehicle Emulator System (VES) platform designed by MIT which is based on Stewart's platform. The inverse position solution is straight-forward and computationally inexpensive. Given the desired position and orientation of the moving platform with respect to the base, the lengths of the prismatic leg actuators are calculated. The forward position solution is more complicated and theoretically has 16 solutions. The position and orientation of the moving platform with respect to the base is calculated given the leg actuator lengths. Two methods are pursued in this paper to solve this problem. The resolved rate (inverse velocity) solution is derived. Given the desired Cartesian velocity of the end-effector, the required leg actuator rates are calculated. The Newton-Raphson Jacobian matrix resulting from the second forward position kinematics solution is a modified inverse Jacobian matrix. Examples and simulations are given for the VES.
Kinematic Point Source Moment Tensor Inversion Using a Hierarchical Bayesian Approach
NASA Astrophysics Data System (ADS)
Musta?, Marija; Tkal?i?, Hrvoje
2014-05-01
The seismic moment tensor (MT) reveals details about source processes within the Earth that cause earthquakes. Although uncertainties in MT inversions are important for estimating solution robustness, they are rarely available. When earthquake location is simultaneously recovered with the MT, uncertainties in structural Green's functions also need to be included in the method. The problem becomes nonlinear and uncertainties in the source mechanism cannot be calculated in a simple manner. We have developed a method and software for a hierarchical Bayesian MT inversion to study moderate earthquakes and explosions generating waveform data at regional distances. The Bayesian inversion gives a posterior probability distribution of model parameters, based on prior knowledge about the MT and the model likelihood, determined by the data. MT uncertainties can then be estimated from the posterior probability distribution. The hierarchical Bayes approach enables us to recover the nature of the data noise and the weight of each waveform, treating them as unknowns in the inversion. Critically, data noise covariance matrix is implemented to account for measurement and theory errors. This knowledge, in turn, enables us to recover the solution within a reasonable range of uncertainty; in other words, it prevents us from "fitting the noise" that can lead to erroneous solutions and interpretation. Synthetic experiments were performed to test the codes, particularly the retrieval of non double-couple components of the MT. A suite of synthetic and observed focal mechanisms was used to create the synthetic data. Additionally, we add noise to synthetic data (as a fraction of data rms) to test its effect on the inversion. Experiments are performed using uncorrelated Gaussian white noise, as well as using correlated noise. Parameter space for the event mechanism is sampled exhaustively, while the code rapidly converges towards the input hypocenter location. Both the input mechanism and noise level were retrieved in the inversion. The codes are currently being applied on real data to test earthquakes in a variety of tectonic settings.
M. Caamaño; O. Delaune; F. Farget; X. Derkx; K. -H. Schmidt; L. Audouin; C. -O. Bacri; G. Barreau; J. Benlliure; E. Casarejos; A. Chbihi; B. Fernandez-Dominguez; L. Gaudefroy; C. Golabek; B. Jurado; A. Lemasson; A. Navin; M. Rejmund; T. Roger; A. Shrivastava; C. Schmitt
2013-04-09
A novel method to access the complete identification in atomic number Z and mass A of fragments produced in low-energy fission of actinides is presented. This method, based on the use of multi- nucleon transfer and fusion reactions in inverse kinematics, is applied in this work to reactions between a 238U beam and a 12C target to produce and induce fission of moderately excited actinides. The fission fragments are detected and fully identified with the VAMOS spectrometer of GANIL, allowing the measurement of fragment yields of several hundreds of isotopes in a range between A ~ 80 and ~ 160, and from Z ~ 30 to ~ 64. For the first time, complete isotopic yield distributions of fragments from well-defined fissioning systems are available. Together with the precise measurement of the fragment emission angles and velocities, this technique gives further insight into the nuclear-fission process.
A three-body model for the analysis of quasi-free scattering reactions in inverse kinematics
Moro, Antonio M
2015-01-01
A new method to calculate cross sections for $(p,pn)$ and $(p,2p)$ reactions measured under inverse kinematics conditions is proposed. The method uses the prior form of the scattering transition amplitude, and replaces the exact three-body wave function appearing in this expression by an expansion in terms of $p$-$n$ or $p$-$p$ states, covering the physically relevant excitation energies and partial waves. A procedure of discretization, similar to that used in continuum-discretized coupled-channels calculations, is applied in order to make this expansion finite and numerically tractable. The proposed formalism is non-relativistic but several relativistic kinematical corrections are applied to extend its applicability to energies of current interest. The underlying optical potentials for the entrance and exit channels are generated microscopically, by folding an effective density-dependent G-matrix with the density of the composite nucleus. Numerical calculations for $^{12}$C($p$,$2p$), $^{12}$C($p$,$pn$) and ...
Kinematic earthquake source inversion and tsunami runup prediction with regional geophysical data
NASA Astrophysics Data System (ADS)
Melgar, D.; Bock, Y.
2015-05-01
Rapid near-source earthquake source modeling relying only on strong motion data is limited by instrumental offsets and magnitude saturation, adversely affecting subsequent tsunami prediction. Seismogeodetic displacement and velocity waveforms estimated from an optimal combination of high-rate GPS and strong motion data overcome these limitations. Supplementing land-based data with offshore wave measurements by seafloor pressure sensors and GPS-equipped buoys can further improve the image of the earthquake source and prediction of tsunami extent, inundation, and runup. We present a kinematic source model obtained from a retrospective real-time analysis of a heterogeneous data set for the 2011 Mw9.0 Tohoku-Oki, Japan, earthquake. Our model is consistent with conceptual models of subduction zones, exhibiting depth dependent behavior that is quantified through frequency domain analysis of slip rate functions. The stress drop distribution is found to be significantly more correlated with aftershock locations and mechanism types when off-shore data are included. The kinematic model parameters are then used as initial conditions in a fully nonlinear tsunami propagation analysis. Notably, we include the horizontal advection of steeply sloping bathymetric features. Comparison with post-event on-land survey measurements demonstrates that the tsunami's inundation and runup are predicted with considerable accuracy, only limited in scale by the resolution of available topography and bathymetry. We conclude that it is possible to produce credible and rapid, kinematic source models and tsunami predictions within minutes of earthquake onset time for near-source coastal regions most susceptible to loss of life and damage to critical infrastructure, regardless of earthquake magnitude.
NASA Astrophysics Data System (ADS)
Twardzik, C.; Madariaga, R. I.; Das, S.; Custodio, S.; Archuleta, R. J.
2011-12-01
We explore a recently developed procedure for kinematic inversion based on elliptical sub-fault approximation. In this method, the slip is modelled by a small set of elliptical patches, each ellipse having a Gaussian distribution of slip. In addition to creating an intrinsically smooth slip distribution inside the slipping region, elliptical patches have the advantage of reducing the number of parameters to invert, since seven parameters are sufficient to describe each patch. We invert near-field strong ground motion data for the 28th September 2004 Parkfield, California, earthquake to test this approach. The dataset consists of 10 digital 3-components 18 s long accelerograms, which were integrated twice to obtain displacement records and filtered between 0.16Hz and 1Hz. Thirty-three digitized analog stations also recorded this earthquake but were not used in the inversion due to absence of absolute timing. However, these stations are used as a additional criteria to test our final model. However, some of these stations are difficult to fit as they lie very close to the fault and exhibit very strong site effects, for example, the influence of fault guided waves which are difficult to model. The best kinematic model is a slip pattern elongated in the strike direction with an average slip of about 0.55 m and a high-slip patch of 1.1 m located 20 km north-west of the hypocenter. Although some studies show evidence of high slip near the hypocenter, we find that the existence of this feature does not improve the fit to the data, and is therefore not resolvable using digital stations only. The final moment is 1.81 x 1018 N m, which is close to the CMT value of 1.13 x 1018 N m. We show that the data can be explained by a rupture propagating at a horizontal speed of 0.9Vs. Our slip distribution is perfectly aligned below a level delineated by small aftershocks at a depth of approximately 6 km, but this level does not coincide with any known structural boundary. By looking at large aftershocks (4
Spectroscopy of {sup 16}O Using {alpha}+{sup 12}C Resonant Scattering in Inverse Kinematics
Ashwood, N. I.; Freer, M.; Bloxham, T. R.; Curtis, N.; Haigh, P. J.; Price, D. L. [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom); Achouri, N. L. [LPC, ISMRA and Universite de Caen, IN2P3 CNRS, 14050 Caen Cedex (France); Catford, W. N.; Harlin, C. W.; Patterson, N. P.; Thomas, J. S. [School of Electronics and Physical Sciences, University of Surrey, Guildford, Surrey, GU2 7XH (United Kingdom); Soic, N. [Rudjer Boskovic Institut, Bijenicka 54, HR-1000, Zagreb (Croatia)
2009-08-26
A measurement of the {alpha}({sup 12}C,{alpha}){sup 12}C reaction has been performed using resonant scattering with a gas target. Beam energies of 46, 51, 56 and 63 MeV were used to populate resonances in the excitation energy range of 11.6 to 22.9 MeV in {sup 16}O. The angular distributions of the elastic scattering were measured at zero degrees using an array of segmented silicon strip detectors with a minimum range of 0 deg. to 30 deg. in the centre of mass. The spins of 8 resonances between 14.1 and 18.5 MeV were obtained, confirming spin assignments made using elastic scattering in normal kinematics. An R-matrix analysis of the data was performed which indicates that the present understanding of {sup 16}O in this region is good, but not complete.
Pin, F.G.; Belmans, P.F.R.; Culioli, J.C.; Carlson, D.D.; Tulloch, F.A.
1994-12-31
A new analytical method to resolve underspecified systems of algebraic equations is presented. The method is referred to as the Full Space Parameterization (FSP) method and utilizes easily- calculated projected solution vectors to generate the entire space of solutions of the underspecified system. Analytic parameterizations for both the space of solutions and the null space of the system reduce the determination of a task-requirement-based single solution to a m {minus} n dimensional problem, where m {minus} n is the degree of underspecification, or degree of redundancy, of the system. An analytical solution is presented to directly calculate the least-norm solution from the parameterized space and the results are compared to solutions of the standard pseudo-inverse algorithm which embodies the (least-norm) Moore-Penrose generalized inverse. Application of the new solution method to a variety of systems and task requirements are discussed and sample results using four-link planar manipulators with one or two degrees of redundancy and a seven degree-of-freedom manipulator with one or four degrees of redundancy are presented to illustrate the efficiency of the new FSP method and algorithm.
NASA Astrophysics Data System (ADS)
Zhang, Y.; Dalguer, L. A.; Song, S.; Clinton, J. F.
2013-12-01
Detailed source imaging of the spatial and temporal slip distribution of earthquakes is a main research goal for seismology. In this study we investigate how the number and geometrical distribution of seismic stations affect finite kinematic source inversion results by inverting ground motions derived from a known synthetic dynamic earthquake rupture model, which is governed by the slip weakening friction law with heterogeneous stress distribution. Our target dynamic rupture model is a buried strike-slip event (Mw 6.5) in a layered half space (Dalguer & Mai, 2011) with broadband synthetic ground motions created at 168 near-field stations. In the inversion, we modeled low frequency (under 1Hz) waveforms using a genetic algorithm in a Bayesian framework (Moneli et al. 2008) to retrieve peak slip velocity, rupture time, and rise time of the source. The dynamic consistent regularized Yoffe function (Tinti et al. 2005) was applied as a single window slip velocity function. Tikhonov regularization was used to smooth final slip. We tested three station network geometry cases: (a) single station, in which we inverted 3 component waveforms from a single station varying azimuth and epicentral distance; (b) multi-station configurations with similar numbers of stations all at similar distances from, but regularly spaced around the fault; (c) irregular multi-station configurations using different numbers of stations. For analysis, waveform misfits are calculated using all 168 stations. Our results show: 1) single station tests suggest that it may be possible to obtain a relatively good source model even using one station, with a waveform misfit comparable to that obtained with the best source model. The best single station performance occurs with stations in which amplitude ratios between the three components are not large, indicating that P & S waves are all present. We infer that both body wave radiation pattern and distance play an important role in selection of optimal station. 2) Multi-station tests indicate irregular distribution of stations with different azimuths and distances around the fault provides the best source models. The minimum waveform misfit is obtained using the all-168 stations, but source model is not significant improved by using denser network. It suggests the best source model is not necessarily derived from the model with minimum waveform misfit. 3) Number of stations affects the estimated source image, but a surprisingly small number of well-spaced stations appear sufficient to obtain acceptable solutions in our study. This study is done under unrealistic conditions, e.g. no noise on ground motions, fault geometry and velocity structure are perfectly known. However, we argue that it provides basic guidelines for seismic / GNSS network geometry for the study source models from real earthquakes. Also, this study suggests a-priori physical constraints for the earthquake source is required to exclude unrealistic models. A pseudo-dynamic source inversion, in which the correlation structures between source parameters inferred from dynamic rupture models (Song et al 2013, in review), will support such constraints, and is currently work in progress.
Pre-stack full wavefield inversion for elastic parameters of TI media
NASA Astrophysics Data System (ADS)
Zhang, Meigen; Huang, Zhongyu; Li, Xiaofan; Wang, Miaoyue; Xu, Guangyin
2006-03-01
Pre-stack full wavefield inversion for the elastic parameters of transversely isotropical media is implemented. The Jacobian matrix is derived directly with the finite element method, just like the full wavefield forward modelling. An absorbing boundary scheme combining Liao's transparent boundary condition with Sarma's attenuation boundary condition is applied to the forward modelling and Jacobian calculation. The input data are the complete ground-recorded wavefields containing full kinematic and dynamic information for the seismic waves. Inversion with such data is desirable as it should improve the accuracy of the estimated parameters and also reduce data pre-processing, such as wavefield identification and separation. A scheme called energy grading inversion is presented to deal with the instability caused by the large energy difference between different arrivals in the input data. With this method, parameters in the shallow areas, which mainly affect wave patterns with strong energy, converge before those of deeper media. Thus, the number of unknowns in each inversion step is reduced, and the stability and reliability of the inversion process is greatly improved. As a result, the scheme is helpful to reduce the non-uniqueness in the inversion. Two synthetic examples show that the inversion system is reliable and accurate even though initial models deviate significantly from the actual models. Also, the system can accurately invert for transversely isotropic model parameters even with the introduction of strong random noise.
NASA Astrophysics Data System (ADS)
Ruiz, S.; Madariaga, R.
2012-04-01
The Maule 2010 Mw 8.8 Chile and Tohoku 2011 Mw 9.0 earthquakes were recorded by continuous GPS (cGPS) and Strong Motion (SM) instruments, with good resolution at low and high frequencies, respectively. The dual behavior of low and high frequencies during large earthquakes is an important issue in seismic hazard because the highest seismic intensities are associated mainly with high frequency waves, while low frequency waves are associated with tsunami generation and the largest coseismic displacements. Previous works proposed that most of the low frequency waves were generated in the shallow part of the contact, while that high frequency waves were released in the deeper zone of the plate interface. We made kinematic inversions in different frequency bands using cGPS and SM to study the seismic ruptures and their frequency behavior. The AXITRA spectral code was used to simulate wave propagation in a flat layered medium. We used two approaches to model the source: elliptical patches and fixed rectangular mesh. Both models fit more than 90% of the variance. Our inversions for Tohoku earthquake show low frequency energy released in the shallow part of the interface and high frequency release in its deeper part, similar to findings in previous works. For Maule, on the other hand, we propose that the main high frequency source was located in the northern part of the rupture, not necessarily in the deeper contact zone that could not be broken during this earthquake. We think that high frequency is concentrated in the boundaries of the rupture caused by the arrest of the rupture propagation. The Maule rupture had a direction of propagation mainly from south to north generating a concentration of high frequency waves in small zones of the northern edge of the rupture. The Tohoku earthquake had a direction of propagation mainly from shallow depth to the deeper part of the plate interface generating more high frequency waves in small zones of the deeper edges. The Maule 2010 earthquake was recorded by several SM that previously recorded the Valparaiso 1985 Mw 8.0 earthquake. The Japanese strong motion networks have recorded several Mw ~ 8.0 earthquakes, like the Tokachi-oki 2003 earthquake. The comparison of SM of both mega-earthquakes with Mw ~ 8.0 earthquakes shows remarkable similarities: similar peak ground acceleration, peak ground velocity, duration of strong motion and high frequency spectrum. These similarities confirm our previous conclusions that high frequency are released by small zones where rupture is stopped by seismic barriers. Finally, the dual frequency behavior of seismic ruptures explains why at high frequencies the seismic intensities for mega-earthquakes are similar to those of Mw ~ 8.0 earthquakes and why for low frequency the seismic hazard of mega-earthquakes is higher generating larger tsunami propagation and coseismic displacements.
NASA Astrophysics Data System (ADS)
Coquard, L.; Ahn, T.; Rainovski, G.; Pietralla, N.; Leske, J.; Möller, O.; Möller, T.; Carpenter, M.; Janssens, R. V. F.; Lister, C. J.; Zhu, S.; Bettermann, L.; Rother, W.
2009-01-01
Coulomb excitation experiments in inverse kinematics on beams of stable 134,132,130,128,126,124Xe ions impinging on a carbon target at energies of 82% of the respective Coulomb barriers have been performed. The one-phonon 21,ms+ states have been tracked and identified in 134,132,130,128Xe from the 2i,ms+?21+ M1 strength distributions and from 01+?2i,ms+ E2 strength distributions responsible for the one-step Coulomb excitation processes. The evolution of the one-phonon 21,ms+ state within the seven even-even stable Xe isotopes is here presented.
Human Hand Kinematic Modeling Based on Robotic Concepts for Digit Animation with Dynamic Constraints
NASA Astrophysics Data System (ADS)
Tondu, Bertrand
The recent development of highly anthropomorphic avatars in computer graphics has emphasized the importance of accurate hand kinematic models. Although kinematic methods derived from robotics have recently been applied to the modeling of hands, we consider that original/new and relevant results can be brought into play with the use of more advanced applications of robotic techniques to human hand kinematic modeling. Our chapter analyses some of these questions both in the non-differential and differential fields. More specifically, we study how to integrate the peculiar natural digit movement constraints into robotics-based inverse kinematic modeling. As a result, we propose an original approach based on an interpretation of each joint dynamic constraint as a linear joint synergy. This leads to defining the considered digit as a serial chain kinematically redundant in position and reducing the dimension of its joint space by associated joint synergies. The method is applied to the Cartesian positioning simulation of a 4 d.o.f. index model; a comparison with a Jacobian pseudo-inverse-based approach emphasizes its relevance.
NASA Astrophysics Data System (ADS)
Jähne, F.; Kley, J.; Hoffmann, V. E.; Eynatten, H. V.; Dunkl, I.
2009-04-01
Late Cretaceous to Early Tertiary inversion of the Central European Basin system (CEBS) is remarkably heterogeneous in the mode and timing of structural inversion (i.e., including reactivation of normal faults). Paleogene inversion present in rifts from the British Isles to the Netherlands decreases eastward into the Lower Saxony basin. Further east, in the North East German basin (NEGB), the influence of Paleocene to Eocene events is difficult to prove. There, much or all of the inversion occurred in Late Cretaceous time. E.g., the Dekorp Basin 9601 regional seismic section shows flat lying Paleocene on top of steeply dipping, folded and thrust-faulted Triassic to Upper Cretaceous strata. Thickness variations of Lower Tertiary strata in the southern NEGB mostly result from differential subsidence by salt withdrawal: salt-cored anticlines subsided after Late Cretaceous inversion and formed up to 1400 m deep basins predominantly filled with Eocene to Oligocene sediments. Fission track dating on bedrock from the basement highs in central Germany supports the hypothesis of a short but intense phase of inversion in Late Cretaceous time, although some Early Tertiary exhumation is documented as well. Apart from the timing of inversion, the different parts of the CEBS differ in the magnitudes of uplift and horizontal shortening and in structural style. In the western and central parts of the basin system, Late Cretaceous shortening is focussed on the NW-SE trending Jurassic to Lower Cretaceous extensional basins. In contrast, little shortening is accommodated within the NEGB. Rather, it is concentrated in the Thüringer Wald, Harz and Flechtingen basement uplifts and associated footwall structures on the southern basin margin. There is no clear evidence for increased original thicknesses of the sedimentary cover overlying the basement uplifts. On the contrary, part of the area affected by basement thrusting was underlain by the Eichsfeld-Altmark swell, a long-lived paleogeographic and structural high of Permian-Jurassic age. There is also no evidence for the regional reverse faults being reactivated normal faults, so the basement thrusting does not represent inversion in a strict sense. Still further east in Poland, the magnitude of "true" basin inversion increases again in the Polish basin. Nevertheless, first results of structural balancing across the CEBS suggest that shortening and uplift attained a maximum on a transect crossing the East German basement uplifts. Bulk horizontal NE-SW shortening from Scandinavia to southern Germany is about 15-20 km there. The total shortening decreases westward to a few km on a southern North Sea transect and probably also toward the east, although regional uplift of the Bohemian Massif inducing widespread non-deposition or erosion of Mesozoic strata make this difficult to prove. The irregular arrangement of extensional basins and intervening highs or swells apparently had a stronger effect on shortening styles than magnitudes. A counterintuitive conclusion from the symmetric regional shortening pattern is that the basins were not mechanically weaker than some specific regions of unextended crust. Rather than particularly strong basins this probably indicates weak basin margins, potentially resulting from a thermal anomaly or a previously thickened felsic crust.
NASA Astrophysics Data System (ADS)
Zegers, R. G. T.; Meharchand, R.; Shimbara, Y.; Austin, Sam M.; Bazin, D.; Brown, B. A.; Diget, C. Aa.; Gade, A.; Guess, C. J.; Hausmann, M.; Hitt, G. W.; Weisshaar, D.; King, M.; Miller, D.; Yurkon, J.; Signoracci, A.; Starosta, K.; Tur, C.; Vaman, C.; Voss, P.; Howard, M. E.; Noji, S.
2010-11-01
Although charge-exchange reactions at intermediate energies with a variety of probes on stable nuclei have long been the preferred tool to extract Gamow-Teller strengths beyond the Q-value window available for ?-decay, the implementation of such reactions for rare isotopes has proven to be an experimental challenge. Here, we report on the first successful extraction of a ?+ Gamow-Teller strength distribution from a radioactive isotope in an intermediate-energy charge-exchange experiment in inverse kinematics. The (^7Li,^7Be+?) reaction at 100 AMeV was used to measure Gamow-Teller transition strengths from ^34P to states in ^34Si. The results show that little mixing occurs between sd and pf shell configurations for the low-lying 0^+ and 2^+ states even though ^34Si neighbors the island of inversion and low-lying intruder states exist.
Multi-GPU Jacobian Accelerated Computing for Soft Field Tomography
Borsic, A.; Attardo, E. A.; Halter, R. J.
2012-01-01
Image reconstruction in soft-field tomography is based on an inverse problem formulation, where a forward model is fitted to the data. In medical applications, where the anatomy presents complex shapes, it is common to use Finite Element Models to represent the volume of interest and to solve a partial differential equation that models the physics of the system. Over the last decade, there has been a shifting interest from 2D modeling to 3D modeling, as the underlying physics of most problems are three-dimensional. Though the increased computational power of modern computers allows working with much larger FEM models, the computational time required to reconstruct 3D images on a fine 3D FEM model can be significant, on the order of hours. For example, in Electrical Impedance Tomography applications using a dense 3D FEM mesh with half a million elements, a single reconstruction iteration takes approximately 15 to 20 minutes with optimized routines running on a modern multi-core PC. It is desirable to accelerate image reconstruction to enable researchers to more easily and rapidly explore data and reconstruction parameters. Further, providing high-speed reconstructions are essential for some promising clinical application of EIT. For 3D problems 70% of the computing time is spent building the Jacobian matrix, and 25% of the time in forward solving. In the present work, we focus on accelerating the Jacobian computation by using single and multiple GPUs. First, we discuss an optimized implementation on a modern multi-core PC architecture and show how computing time is bounded by the CPU-to-memory bandwidth; this factor limits the rate at which data can be fetched by the CPU. Gains associated with use of multiple CPU cores are minimal, since data operands cannot be fetched fast enough to saturate the processing power of even a single CPU core. GPUs have a much faster memory bandwidths compared to CPUs and better parallelism. We are able to obtain acceleration factors of 20 times on a single NVIDIA S1070 GPU, and of 50 times on 4 GPUs, bringing the Jacobian computing time for a fine 3D mesh from 12 minutes to 14 seconds. We regard this as an important step towards gaining interactive reconstruction times in 3D imaging, particularly when coupled in the future with acceleration of the forward problem. While we demonstrate results for Electrical Impedance Tomography, these results apply to any soft-field imaging modality where the Jacobian matrix is computed with the Adjoint Method. PMID:23010857
The ALPAL Matrix Editor for symbolic Jacobians
Painter, J.F.
1990-04-01
ALPAL is a tool that automatically generates code to solve nonlinear integro-differential equations, given a very high-level specification of the equations to be solved and the numerical methods to be used. Its Matrix Editor is brought into play when an ALPAL user wants to use an implicit time-integration scheme. The Matrix Editor is a graphical, interactive tool for specifying the handling of Jacobian matrices and linear solvers. Such specification is done at a very high level of abstraction, and is applied to symbolically defined Jacobian matrices. 4 refs., 2 figs.
Singularity analysis of closed-loop kinematic chains
C. Gosselin; J. Angeles
1990-01-01
The different kinds of singularities encountered in closed-loop kinematics chains are analyzed. A general classification of these singularities in three main groups, which is based on the properties of the Jacobian matrices of the chain, is described. The identification of the singular configurations is particularly relevant for hard automation modules or robotic devices based on closed kinematic chains, such as
Suzuki, T.; Rainovski, G.; Koike, T.; Ahn, T.; Carpenter, M. P.; Costin, A.; Danchev, M.; Dewald, A.; Janssens, R. V. F.; Joshi, P.; Lister, C. J.; Moller, A.; Pietralla, N.; Shinozuka, T.; Timar, J.; Wadsworth, R.; Vaman, C.; Zhu, S.; Physics; Tohoku Univ.; Univ. of Sofia; State Univ. of New York; Univ. of Tennessee; Univ. zu Koln; Univ. of York; TU Darmstadt; ATOMKI, Hungary; Michigan State Univ.
2008-01-01
Lifetimes of chiral candidate structures in {sup 103,104}Rh were measured using the recoil distance Doppler-shift method. The Gammasphere detector array was used in conjunction with the Cologne plunger device. Excited states of {sup 103,104}Rh were populated by the {sup 11}B({sup 96}Zr,4n){sup 103}Rh and {sup 11}B({sup 96}Zr,3n){sup 104}Rh fusion-evaporation reactions in inverse kinematics. Three and five lifetimes of levels belonging to the proposed chiral doublet bands are measured in {sup 103}Rh and {sup 104}Rh, respectively. The previously observed even-odd spin dependence of the B(M1)/B(E2) values is caused by the variation in the B(E2) values, whereas the B(M1) values decrease as a function of spin.
NASA Astrophysics Data System (ADS)
Margerin, V.; Lotay, G.; Woods, P. J.; Aliotta, M.; Christian, G.; Davids, B.; Davinson, T.; Doherty, D. T.; Fallis, J.; Howell, D.; Kirsebom, O. S.; Mountford, D. J.; Rojas, A.; Ruiz, C.; Tostevin, J. A.
2015-08-01
In Wolf-Rayet and asymptotic giant branch (AGB) stars, the Alg26(p ,? )27Si reaction is expected to govern the destruction of the cosmic ? -ray emitting nucleus 26Al. The rate of this reaction, however, is highly uncertain due to the unknown properties of key resonances in the temperature regime of hydrogen burning. We present a high-resolution inverse kinematic study of the Alg26(d ,p )27Al reaction as a method for constraining the strengths of key astrophysical resonances in the Alg26(p ,? )27Si reaction. In particular, the results indicate that the resonance at Er=127 keV in 27Si determines the entire Alg26(p ,? )27Si reaction rate over almost the complete temperature range of Wolf-Rayet stars and AGB stars.
Hacker, C.J.; Fries, G.A.; Pin, F.G.
1997-01-01
Few optimization methods exist for path planning of kinematically redundant manipulators. Among these, a universal method is lacking that takes advantage of a manipulator`s redundancy while satisfying possibly varying constraints and task requirements. Full Space Parameterization (FSP) is a new method that generates the entire solution space of underspecified systems of algebraic equations and then calculates the unique solution satisfying specific constraints and optimization criteria. The FSP method has been previously tested on several configurations of the redundant manipulator HERMIES-III. This report deals with the extension of the FSP driver, Inverse Kinematics On Redundant systems (IKOR), to include three-dimensional manipulation systems, possibly incorporating a mobile platform, with and without orientation control. The driver was also extended by integrating two optimized versions of the FSP solution generator as well as the ability to easily port to any manipulator. IKOR was first altered to include the ability to handle orientation control and to integrate an optimized solution generator. The resulting system was tested on a 4 degrees-of-redundancy manipulator arm and was found to successfully perform trajectories with least norm criteria while avoiding obstacles and joint limits. Next, the system was adapted and tested on a manipulator arm placed on a mobile platform yielding 7 degrees of redundancy. After successful testing on least norm trajectories while avoiding obstacles and joint limits, IKORv1.0 was developed. The system was successfully verified using comparisons with a current industry standard, the Moore Penrose Pseudo-Inverse. Finally, IKORv2.0 was created, which includes both the one shot and two step methods, manipulator portability, integration of a second optimized solution generator, and finally a more robust and usable code design.
Kinematics, Kinematics Chains Previously!
Kosecka, Jana
1! Kinematics, Kinematics Chains CS 685! Previously! · Representation of rigid body motion! · Two A ! Composite transformation: ! Transformation: ! XA = RAB tAB 0 1 XB Homogeneous coordinates ! Kinematic rigid bodies lined together (e.g. robot manipulator) ! · Kinematics study of position, orientation
A Neuro-Sliding Mode Control Scheme for Constrained Robots with Uncertain Jacobian
R. García-rodríguez; Vicente Parra-vega
2009-01-01
The joint robot control requires to map desired cartesian tasks into desired joint trajectories, by using the ill-posed inverse\\u000a kinematics mapping. In order to avoid inverse kinematics, the control problem is formulated directly in task space to gives\\u000a rise to cartesian robot control. In addition, when the robot is constrained due to its kinematic mappings yields a stiff system\\u000a and
NASA Astrophysics Data System (ADS)
Yue, Han
In this thesis, I summarize the research that I have done at UC Santa Cruz involving my development of joint inversion approaches using hr-GPS, teleseismic body and surface waves, regional seismic, campaign GPS, InSAR and tsunami datasets, to investigate the kinematic rupture patterns of large earthquakes. In eight different studies of rupture models of the 2011 Tohoku earthquake, 2012 Indo-Australia earthquake, 2012 Costa Rica earthquake, 2013 Craig earthquake, 2010 Mentawai earthquake, 2013 Pakistan earthquake, 2010 Chile earthquake and 2014 Iquique earthquake, I adopted each available dataset progressively in my joint inversion algorithm, so that in my current approach I can model all of the types of datasets simultaneously. As noted in this thesis, the teleseismic datasets provide good temporal resolution of the rupture process, while geodetic datasets have good spatial resolution. Tsunami datasets have good spatial resolution of slip near the trench. The joint inversion combines the advantage of each dataset, yielding stable and high- resolution rupture models with detailed spatial and temporal information. Resolving a robust and detailed rupture model helps us to understand co-seismic rupture properties, such as depth dependent energy release patterns, super-shear rupture, and tsunami excitation. Comparing the inter-seismic locking pattern and post-seismic stress release pattern with the co-seismic rupture model helps to investigate the locking and releasing behavior of the fault plane through the earthquake cycle, the stress release level of large earthquakes and the relationship between the main shock ruptures, aftershocks and non-seismogenic deformation.
NASA Astrophysics Data System (ADS)
Coutand, Isabelle; Whipp, David, Jr.; Grujic, Djordje; Bernet, Matthias; Giuditta Fellin, Maria; Bookhagen, Bodo; Landry, Kyle; Ghalley, Kharka; Duncan, Chris
2014-05-01
Both climatic and tectonic processes affect bedrock erosion and exhumation in convergent orogens, but determining their respective influence is difficult. A requisite first step is to quantify long-term (~10 ^ 6 yr) erosion rates within an orogen. In the Himalaya, past studies suggest long-term erosion rates varied in space and time along the range front, resulting in numerous tectonic models to explain the observed erosion rate distribution. Here, we invert a large dataset of new and existing thermochronological ages to determine both long-term exhumation rates and the kinematics of Neogene tectonic activity in the eastern Himalaya in Bhutan. New data include 31 apatite and 5 zircon (U-Th)/He ages, and 49 apatite and 16 zircon fission-track ages along two North-South oriented transects across the orogen in western and eastern Bhutan. Data inversion was performed using a modified version of the 3-D thermo-kinematic model PECUBE, with parameter ranges defined by available geochronologic, metamorphic, structural and geophysical data. Among several important observations, our three main conclusions are: (1) Thermochronologic ages do not spatially correlate with surface traces of major fault zones, but appear to reflect the geometry of the underlying Main Himalayan Thrust; (2) our data are compatible with a strong tectonic influence, involving a variably dipping Main Himalayan Thrust geometry and steady-state topography; and (3) erosion rates have remained constant in western Bhutan over the last ~10 Ma, while a significant decrease occurred at ~6 Ma in eastern Bhutan, which we partially attribute to convergence partitioning into uplift of the Shillong plateau.
Kinematic analysis of 7 DOF anthropomorphic arms
NASA Technical Reports Server (NTRS)
Kreutz-Delgado, K.; Long, M.; Seraji, H.
1990-01-01
A kinematic analysis of anthropomorphic seven-degree-of-freedom serial link spatial manipulators with revolute joints is presented. To uniquely determine joint angles for a given end-effector position and orientation, the redundancy is parameterized by a scalar variable which corresponds to the angle between the arm plane and a reference plane. The forward kinematic mappings from joint-space to end-effector coordinates and arm angle and the augmented Jacobian matrix which gives end-effector and arm angle rates as functions of joint rates are given. Conditions under which the augmented Jacobian becomes singular are given and are shown to correspond to the arm being either at a kinematically singular configuration or at a nonsingular configuration for which the arm angle ceases to parameterize the redundancy.
Kinematic analysis of 7-DOF manipulators
NASA Technical Reports Server (NTRS)
Kreutz-Delgado, Kenneth; Long, Mark; Seraji, Homayoun
1992-01-01
This article presents a kinematic analysis of seven-degree-of-freedom serial link spatial manipulators with revolute joints. To uniquely determine the joint angles for a given end-effector position and orientation, the redundancy is parameterized by a scalar variable that defines the angle between the arm plane and a reference plane. The forward kinematic mappings from joint space to end-effector coordinates and arm angle and the augmented Jacobian matrix that gives end-effector and arm angle rates as functions of joint rates are presented. Conditions under which the augmented Jacobian becomes singular are also given and are shown to correspond to the arm being either at a kinematically singular configuration or at a nonsingular configuration for which the arm angle ceases to parameterize the redundancy.
A Jacobian elliptic single-field inflation
NASA Astrophysics Data System (ADS)
Villanueva, J. R.; Gallo, Emanuel
2015-06-01
In the scenario of single-field inflation, this field is described in terms of Jacobian elliptic functions. This approach provides, when constrained to particular cases, analytic solutions already known in the past, generalizing them to a bigger family of analytical solutions. The emergent cosmology is analyzed using the Hamilton-Jacobi approach and then the main results are contrasted with the recent measurements obtained from the Planck 2015 data.
A Jacobian elliptic single-field inflation
Villanueva, J R
2015-01-01
In the scenario of single-field inflation, this field is done in terms of Jacobian elliptic functions. This approach provides, when constrained to particular cases, analytic solutions already known in the past, generalizing them to a bigger family of analytical solutions. The emergent cosmology is analysed using the Hamilton-Jacobi approach and then, the main results are contrasted with the recent measurements obtained from the Planck 2015 data.
NASA Astrophysics Data System (ADS)
Sasano, M.; Perdikakis, G.; Zegers, R. G. T.; Austin, Sam M.; Bazin, D.; Brown, B. A.; Caesar, C.; Cole, A. L.; Deaven, J. M.; Ferrante, N.; Guess, C. J.; Hitt, G. W.; Honma, M.; Meharchand, R.; Montes, F.; Palardy, J.; Prinke, A.; Riley, L. A.; Sakai, H.; Scott, M.; Stolz, A.; Suzuki, T.; Valdez, L.; Yako, K.
2012-09-01
Background: Gamow-Teller (GT) transition strength distributions in stable and unstable pf-shell isotopes are key inputs for estimating electron-capture rates important for stellar evolution. Charge-exchange experiments at intermediate beam energies have long been used to test theoretical predictions for GT strengths, but previous experiments were largely restricted to stable nuclei. Since a large fraction of the nuclei relevant for astrophysical applications (including key nuclei such as 56Ni) are unstable, new methods are needed to perform charge-exchange experiments in inverse kinematics with unstable isotopes.Purpose: The 56Ni(p,n) and 55Co(p,n) reactions were measured in inverse kinematics in order to extract GT strengths for transitions to 56Cu and 55Ni, respectively. The extracted strength distributions were compared with shell-model predictions in the pf shell using the KB3G and GXPF1J interactions. By invoking isospin symmetry, these strength distributions are relevant for electron captures on the ground states of 56Ni and 55Ni to final states in 56Co and 55Co, respectively.Method: Differential cross sections and excitation energy spectra for the 56Ni(p,n) and 55Co(p,n) reactions were determined by measuring neutrons recoiling from a liquid hydrogen target into the Low Energy Neutron Detector Array. GT contributions to the spectra were extracted by using a multipole decomposition analysis and were converted to strengths by employing the proportionality between GT strength and differential cross section at zero linear momentum transfer.Results: GT strengths from 56Ni and 55Co were extracted up to excitation energies of 8 and 15 MeV, respectively. Shell-model calculations performed in the pf shell with the GXPF1J interaction reproduced the experimental GT strength distributions better than calculations with the KB3G interaction.Conclusions: A new technique for measuring (p,n) charge-exchange reactions on unstable nuclei was successfully developed. It can be used to study the isovector response of unstable nuclei in any mass region and for excitation energies beyond the particle decay threshold. In the first experiment, 56Ni(p,n) and 55Co(p,n) reactions were studied and GT transition strengths were extracted for the purpose of testing shell-model calculations used to estimate electron-capture rates in simulations of late stellar evolution. The calculation using the GXPF1J interaction was found to best reproduce the experimental strength distribution.
Differential Kinematics Of Contemporary Industrial Robots
NASA Astrophysics Data System (ADS)
Szkodny, T.
2014-08-01
The paper presents a simple method of avoiding singular configurations of contemporary industrial robot manipulators of such renowned companies as ABB, Fanuc, Mitsubishi, Adept, Kawasaki, COMAU and KUKA. To determine the singular configurations of these manipulators a global form of description of the end-effector kinematics was prepared, relative to the other links. On the basis of this description , the formula for the Jacobian was defined in the end-effector coordinates. Next, a closed form of the determinant of the Jacobian was derived. From the formula, singular configurations, where the determinant's value equals zero, were determined. Additionally, geometric interpretations of these configurations were given and they were illustrated. For the exemplary manipulator, small corrections of joint variables preventing the reduction of the Jacobian order were suggested. An analysis of positional errors, caused by these corrections, was presented
Kinematic programming alternatives for redundant manipulators
John Baillieul
1985-01-01
In the growing literature on redundant manipulator control, a number of techniques have been proposed for solving the inverse kinemetics problem. Some of these techniques are surveyed with a discussion of strengths and weaknesses of each. A new approach, called the extended Jacobian technique, is also presented. It is argued that because this technique may be expected to lift closed
NASA Astrophysics Data System (ADS)
Kortyna, C. D.; DeCelles, P. G.; Carrapa, B.
2012-12-01
The Eastern Cordillera and Santa Barbara systems of northwest Argentina exhibit a transition in structural style between thick- and thin-skinned features. Traditionally, Andean foreland structural geometries are correlated with the orientation of the subducting Nazca Plate. However, deformation in northwest Argentina is controlled by inversion of inherited Cretaceous rift structures of the Salta rift. South of Salta, in the ranges surrounding the Calchaquí and Lerma Valleys (between ~25°-26°S and ~65°-66°W), the foreland thrust belt is characterized by steep west-verging, north-south trending reverse faults juxtaposing Precambrian-Cambrian basement rocks on Mesozoic-Cenozoic syn-to-post-rift and foreland basin deposits. Geologic mapping, structural data and stratigraphic relationships confirm that these reverse faults are primarily reactivated extensional faults of the Cretaceous Salta rift, a complex of extensional basins beneath the modern foreland basin. The rift geometry provides a major control on fold and fault geometries in the area. New detailed (1:24,000 scale) geologic mapping in the Amblayo, Tonco, and Calchaquí Valleys documents a transition in structural style in the Andean thrust belt that correlates with palinspastic geometries of the Salta rift basin. The southern region correlates with the Salta rift flanks whereas the northern region correlates with the rift interior. Reverse faulting in the southern region is characterized by multiple high angle splays (~40°-70°) with variable amounts of stratigraphic separation that, in places, shortcut high angle normal faults of the Salta rift. In the northern region, reverse faulting is less steep (~25°-50°) and is characterized by a singular fault plane that juxtaposes overturned fault propagation folds in the hanging wall and footwall. Overturned limbs are shallowly dipping at ~20°-30°. Fault planes are approximated by thick, m's-scale orange fault gouge and breccia. This study also describes a new synorogenic unit that constrains timing of rift inversion. Described in north Tonco Valley, this unit consists of localized poorly sorted granular-boulder conglomerates and breccias with a poorly sorted mud-to-coarse sand matrix. The breccia outcrops unconformably on underlying Miocene Angastaco Formation and is in faulted contact with overriding Salta Group. Clasts consist primarily of stromatolitic, oolitic, and micritic limestones with subordinate meta-sandstones and mudstones. The larger, angular clasts are almost uniformly limestone and interpreted to be sourced from the Yacoraite Formation that outcrops in the overlying hanging wall. This unit was deposited as synorogenic muddy debris flows to mud slurries derived locally from the Yacoraite Formation as it was exhumed during fault-propagation folding in the hanging wall of the main reverse fault that juxtaposes the Amblayo and Tonco Valleys. The unit was then overridden by the hanging wall strata as the main fault reached the surface. The youngest detrital U-Pb zircon age population combined with low-T-thermochronology will help constrain timing of deformation along this fault and in the region.
Piatanesi, A.; Cirella, A.; Spudich, P.; Cocco, M.
2007-01-01
We present a two-stage nonlinear technique to invert strong motions records and geodetic data to retrieve the rupture history of an earthquake on a finite fault. To account for the actual rupture complexity, the fault parameters are spatially variable peak slip velocity, slip direction, rupture time and risetime. The unknown parameters are given at the nodes of the subfaults, whereas the parameters within a subfault are allowed to vary through a bilinear interpolation of the nodal values. The forward modeling is performed with a discrete wave number technique, whose Green's functions include the complete response of the vertically varying Earth structure. During the first stage, an algorithm based on the heat-bath simulated annealing generates an ensemble of models that efficiently sample the good data-fitting regions of parameter space. In the second stage (appraisal), the algorithm performs a statistical analysis of the model ensemble and computes a weighted mean model and its standard deviation. This technique, rather than simply looking at the best model, extracts the most stable features of the earthquake rupture that are consistent with the data and gives an estimate of the variability of each model parameter. We present some synthetic tests to show the effectiveness of the method and its robustness to uncertainty of the adopted crustal model. Finally, we apply this inverse technique to the well recorded 2000 western Tottori, Japan, earthquake (Mw 6.6); we confirm that the rupture process is characterized by large slip (3-4 m) at very shallow depths but, differently from previous studies, we imaged a new slip patch (2-2.5 m) located deeper, between 14 and 18 km depth. Copyright 2007 by the American Geophysical Union.
A First-Estimates Jacobian EKF for Improving SLAM Consistency
Roumeliotis, Stergios I.
A First-Estimates Jacobian EKF for Improving SLAM Consistency Guoquan P. Huang1 , Anastasios I of EKF-based SLAM from the perspective of observability. We analytically prove that when the Jacobians that of the actual, nonlinear, SLAM system. As a result, the covariance estimates of the EKF undergo reduction
NASA Astrophysics Data System (ADS)
Coutand, Isabelle; Whipp, David M.; Grujic, Djordje; Bernet, Matthias; Fellin, Maria Giuditta; Bookhagen, Bodo; Landry, Kyle R.; Ghalley, S. K.; Duncan, Chris
2014-02-01
Both climatic and tectonic processes affect bedrock erosion and exhumation in convergent orogens, but determining their respective influence is difficult. A requisite first step is to quantify long-term (~106 year) erosion rates within an orogen. In the Himalaya, past studies suggest long-term erosion rates varied in space and time along the range front, resulting in numerous tectonic models to explain the observed erosion rate distribution. Here, we invert a large data set of new and existing thermochronological ages to determine both long-term exhumation rates and the kinematics of Neogene tectonic activity in the eastern Himalaya in Bhutan. New data include 31 apatite and five zircon (U-Th)/He ages, and 49 apatite and 16 zircon fission-track ages along two north-south oriented transects across the orogen in western and eastern Bhutan. Data inversion was performed using a modified version of the 3-D thermokinematic model Pecube, with parameter ranges defined by available geochronologic, metamorphic, structural, and geophysical data. Among several important observations, our three main conclusions are as follows: (1) Thermochronologic ages do not spatially correlate with surface traces of major fault zones but appear to reflect the geometry of the underlying Main Himalayan Thrust; (2) our data are compatible with a strong tectonic influence, involving a variably dipping Main Himalayan Thrust geometry and steady state topography; and (3) erosion rates have remained constant in western Bhutan over the last ~10 Ma, while a significant decrease occurred at ~6 Ma in eastern Bhutan, which we partially attribute to convergence partitioning into uplift of the Shillong Plateau.
Kinematic control of redundant robot manipulators: A tutorial
Bruno Siciliano
1990-01-01
In this paper, we present a tentatively comprehensive tutorial report of the most recent literature on kinematic control of redundant robot manipulators. Our goal is to lend some perspective to the most widely adopted on-line instantaneous control solutions, namely those based on the simple manipulator's Jacobian, those based on the local optimization of objective functions in the null space of
LOW-RANK QUASI-NEWTON UPDATES FOR ROBUST JACOBIAN LAGGING IN NEWTON METHODS
Brown, Jed
, Idaho, May 5-9, 2013 #12;Jacobian by several iterations or adopt a Jacobian-free Newton-Krylov approach Newton-Krylov solution of nonlinear problems is in the repeated assembly of the Jacobian matrixLOW-RANK QUASI-NEWTON UPDATES FOR ROBUST JACOBIAN LAGGING IN NEWTON METHODS Jed Brown and Peter
Chu, Kevin T.
to avoid computation of the full Jacobian. While Jacobian-free methods, such as the NewtonKrylov method: Analytical Jacobian Numerical methods Matrix calculus Newton's method Integro-differential equations a b iteration of the classical formulation of Newton's method. Unfortunately, calculation of the Jacobian can
Optimized Jacobian Matrix Solution of a generalized electric power network
Moore, Jimmie Archer
1970-01-01
in obtaining solutions to the power flow problem by Newton's method using a Jacobian matrix wl!ich had been "optimized. " Tha. t is, the rows and columns of the Jacobian were rearranged, so as to use only a rear minimum of non-zero te. ms in the upoer...OPI "liEZD JACOBIAN i'MATRIX OLUT "ON OF A GENERALIZED ELECTRIC PONER NETNORK A Thesis by JiI~AIE ARCRER NOOIE Suhmitted to the G-adua. e Col'ege of T x-s APN 'Jniuersity in partial fulfills, ent of the requirement for the de:ree of NASTFR...
Jacobian Joint Adaptation to Noise, Channel and Vocal Tract Length
Shimodaira, Hiroshi; Sakai, Nobuyoshi; Nakai, Mitsuru; Sagayama, Shigeki
A new Jacobian approach that linearly decomposes the composite of additive noise, multiplicative noise (channel transfer function) and speaker's vocal tract length, and adapts the acoustic model parameters simultaneously ...
Crystal plasticity with Jacobian-Free Newton-Krylov
NASA Astrophysics Data System (ADS)
Chockalingam, K.; Tonks, M. R.; Hales, J. D.; Gaston, D. R.; Millett, P. C.; Zhang, Liangzhe
2013-05-01
The objective of this work is to study potential benefits of solving crystal plasticity finite element method (CPFEM) implicit simulations using the Jacobian-Free Newton-Krylov (JFNK) technique. Implicit implementations of CPFEM are usually solved using Newton's method. However, the inherent non-linearity in the flow rule model that characterizes the crystal slip system deformation on occasions would require considerable effort to form the exact analytical Jacobian needed by Newton's method. In this paper we present an alternative using JFNK. As it does not require an exact Jacobian, JFNK can potentially decrease development time. JFNK approximates the effect of the Jacobian through finite differences of the residual vector, allowing modified formulations to be studied with relative ease. We show that the JFNK solution is identical to that obtained using Newton's method and produces quadratic convergence. We also find that preconditioning the JFNK solution with the elastic tensor provides the best computational efficiency.
Computational recipes for electromagnetic inverse problems
NASA Astrophysics Data System (ADS)
Egbert, Gary D.; Kelbert, Anna
2012-04-01
The Jacobian of the non-linear mapping from model parameters to observations is a key component in all gradient-based inversion methods, including variants on Gauss-Newton and non-linear conjugate gradients. Here, we develop a general mathematical framework for Jacobian computations arising in electromagnetic (EM) geophysical inverse problems. Our analysis, which is based on the discrete formulation of the forward problem, divides computations into components (data functionals, forward and adjoint solvers, model parameter mappings), and clarifies dependencies among these elements within realistic numerical inversion codes. To be concrete, we focus much of the specific discussion on 2-D and 3-D magnetotelluric (MT) inverse problems, but our analysis is applicable to a wide range of active and passive source EM methods. The general theory developed here provides the basis for development of a modular system of computer codes for inversion of EM geophysical data, which we summarize at the end of the paper.
Roberts, R.G. [FAMU-FSU College of Engineering, Tallahassee, FL (United States). Dept. of Electrical Engineering] [FAMU-FSU College of Engineering, Tallahassee, FL (United States). Dept. of Electrical Engineering; Repperger, D.W. [AFRL/HECP, Wright Patterson AFB, OH (United States)] [AFRL/HECP, Wright Patterson AFB, OH (United States)
1999-01-01
This article presents some results on the closed-form, singular-value decomposition of the orientational Jacobian for three- and four-degree-of-freedom wristlike mechanisms. These results are used to study the kinematics of a centrifuge simulator, and to determine the centrifuge`s limitations in achieving maximum angular velocities. Also, the issue of fault tolerance for a redundant wrist is addressed.
Kinematic analysis of the ARID manipulator
NASA Technical Reports Server (NTRS)
Doty, Keith L
1992-01-01
The kinematic structure of the ARID manipulator lends itself to simple forward and inverse kinematics analysis. The purpose of this paper is to fully document and verify an existing analysis. The symbolic software package MATHEMATICA was used to produce and verify the equations presented here. In the analysis to follow, the standard Devenit-Hartenberg kinematic parameters of the ARID were employed.
Direct kinematic solution of a Stewart platform
PRABJOT NANUA; KENNETH J. WALDRON; VASUDEVA MURTHY
1990-01-01
The Stewart platform is a fully parallel, six-degree-of-freedom manipulator mechanism. Although its inverse kinematics have been extensively studied, no solutions to the direct position kinematics problem have been previously presented in the literature. A solution of the direct kinematics problem of the case in which the six limbs form three concurrent pairs at either the base or the hand member
Optimum Kinematic Design for a Seven Degree of Freedom Manipulator
John M. Hollerbach
1985-01-01
oll axes of the forearm andhand, reducing by one the degrees of freedom.Singularities are manifested in inverse kinematicproblems where it is desired to find joint velocitiesthat correspond to desired hand velocities. Joint velocities` and hand velocities x are related by theJacobian matrix J: x = J `where the 6-dimensional hand velocity x = ( p !)consists of a linear velocity
Qin, Jin; Trudeau, Matthieu; Buchholz, Bryan; Katz, Jeffrey N; Xu, Xu; Dennerlein, Jack T
2014-04-01
Upper extremity kinematics during keyboard use is associated with musculoskeletal health among computer users; however, specific kinematics patterns are unclear. This study aimed to determine the dynamic roles of the shoulder, elbow, wrist and metacarpophalangeal (MCP) joints during a number entry task. Six subjects typed in phone numbers using their right index finger on a stand-alone numeric keypad. The contribution of each joint of the upper extremity to the fingertip movement during the task was calculated from the joint angle trajectory and the Jacobian matrix of a nine-degree-of-freedom kinematic representation of the finger, hand, forearm and upper arm. The results indicated that in the vertical direction where the greatest fingertip movement occurred, the MCP, wrist, elbow (including forearm) and shoulder joint contributed 10.2%, 55.6%, 27.7% and 6.5%, respectively, to the downward motion of the index finger averaged across subjects. The results demonstrated that the wrist and elbow contribute the most to the fingertip vertical movement, indicating that they play a major role in the keying motion and have a dynamic load beyond maintaining posture. PMID:24144858
Multi-GPU Jacobian accelerated computing for soft-field tomography.
Borsic, A; Attardo, E A; Halter, R J
2012-10-01
Image reconstruction in soft-field tomography is based on an inverse problem formulation, where a forward model is fitted to the data. In medical applications, where the anatomy presents complex shapes, it is common to use finite element models (FEMs) to represent the volume of interest and solve a partial differential equation that models the physics of the system. Over the last decade, there has been a shifting interest from 2D modeling to 3D modeling, as the underlying physics of most problems are 3D. Although the increased computational power of modern computers allows working with much larger FEM models, the computational time required to reconstruct 3D images on a fine 3D FEM model can be significant, on the order of hours. For example, in electrical impedance tomography (EIT) applications using a dense 3D FEM mesh with half a million elements, a single reconstruction iteration takes approximately 15-20 min with optimized routines running on a modern multi-core PC. It is desirable to accelerate image reconstruction to enable researchers to more easily and rapidly explore data and reconstruction parameters. Furthermore, providing high-speed reconstructions is essential for some promising clinical application of EIT. For 3D problems, 70% of the computing time is spent building the Jacobian matrix, and 25% of the time in forward solving. In this work, we focus on accelerating the Jacobian computation by using single and multiple GPUs. First, we discuss an optimized implementation on a modern multi-core PC architecture and show how computing time is bounded by the CPU-to-memory bandwidth; this factor limits the rate at which data can be fetched by the CPU. Gains associated with the use of multiple CPU cores are minimal, since data operands cannot be fetched fast enough to saturate the processing power of even a single CPU core. GPUs have much faster memory bandwidths compared to CPUs and better parallelism. We are able to obtain acceleration factors of 20 times on a single NVIDIA S1070 GPU, and of 50 times on four GPUs, bringing the Jacobian computing time for a fine 3D mesh from 12 min to 14 s. We regard this as an important step toward gaining interactive reconstruction times in 3D imaging, particularly when coupled in the future with acceleration of the forward problem. While we demonstrate results for EIT, these results apply to any soft-field imaging modality where the Jacobian matrix is computed with the adjoint method. PMID:23010857
Kügler, Philipp; Yang, Wei
2014-06-01
Model building of biochemical reaction networks typically involves experiments in which changes in the behavior due to natural or experimental perturbations are observed. Computational models of reaction networks are also used in a systems biology approach to study how transitions from a healthy to a diseased state result from changes in genetic or environmental conditions. In this paper we consider the nonlinear inverse problem of inferring information about the Jacobian of a Langevin type network model from covariance data of steady state concentrations associated to two different experimental conditions. Under idealized assumptions on the Langevin fluctuation matrices we prove that relative alterations in the network Jacobian can be uniquely identified when comparing the two data sets. Based on this result and the premise that alteration is locally confined to separable parts due to network modularity we suggest a computational approach using hybrid stochastic-deterministic optimization for the detection of perturbations in the network Jacobian using the sparsity promoting effect of [Formula: see text]-penalization. Our approach is illustrated by means of published metabolomic and signaling reaction networks. PMID:23708492
Jacobian variety and Integrable system -- after Mumford, Beauville and Vanhaecke
Rei Inoue; Yukiko Konishi; Takao Yamazaki
2006-06-12
Beauville introduced an integrable Hamiltonian system whose general level set is isomorphic to the complement of the theta divisor in the Jacobian of the spectral curve. This can be regarded as a generalization of the Mumford system. In this article, we construct a variant of Beauville's system whose general level set is isomorphic to the complement of the `intersection' of the translations of the theta divisor in the Jacobian. A suitable subsystem of our system can be regarded as a generalization of the even Mumford system introduced by Vanhaecke.
Power system steady-state stability and the load-flow Jacobian
Sauer, P.W.; Pai, M.A. (Illinois Univ., Urbana, IL (USA). Dept. of Electrical and Computer Engineering)
1990-11-01
This paper presents the relationship between a detailed power system dynamic model and a standard load-flow model. The linearized dynamic model is examined to show how the load-flow Jacobian appears in the system dynamic state Jacobian for evaluating steady-state stability. Two special cases are given for the situation when singularity of the load-flow Jacobian implies singularity of the system dynamic state Jacobian.
Margerin, V; Lotay, G; Woods, P J; Aliotta, M; Christian, G; Davids, B; Davinson, T; Doherty, D T; Fallis, J; Howell, D; Kirsebom, O S; Mountford, D J; Rojas, A; Ruiz, C; Tostevin, J A
2015-08-01
In Wolf-Rayet and asymptotic giant branch (AGB) stars, the ^{26g}Al(p,?)^{27}Si reaction is expected to govern the destruction of the cosmic ?-ray emitting nucleus ^{26}Al. The rate of this reaction, however, is highly uncertain due to the unknown properties of key resonances in the temperature regime of hydrogen burning. We present a high-resolution inverse kinematic study of the ^{26g}Al(d,p)^{27}Al reaction as a method for constraining the strengths of key astrophysical resonances in the ^{26g}Al(p,?)^{27}Si reaction. In particular, the results indicate that the resonance at E_{r}=127??keV in ^{27}Si determines the entire ^{26g}Al(p,?)^{27}Si reaction rate over almost the complete temperature range of Wolf-Rayet stars and AGB stars. PMID:26296114
Solving Nonlinear Solid Mechanics Problems with the Jacobian-Free Newton Krylov Method
J. D. Hales; S. R. Novascone; R. L. Williamson; D. R. Gaston; M. R. Tonks
2012-01-01
The solution of the equations governing solid mechanics is often obtained via Newton's method. This approach can be problematic if the determination, storage, or solution cost associated with the Jacobian is high. These challenges are magnified for multiphysics applications with many coupled variables. Jacobian-free Newton-Krylov (JFNK) methods avoid many of the difficulties associated with the Jacobian by using a finite
ATLAS MOTION PLATFORM MECANUM WHEEL JACOBIAN IN THE VELOCITY AND STATIC FORCE DOMAINS
Hayes, John
ATLAS MOTION PLATFORM MECANUM WHEEL JACOBIAN IN THE VELOCITY AND STATIC FORCE DOMAINS Jonathan J and static force Jacobians; normal forces. JACOBIAN DES ROUES MECANUM DU PLATFORME DE MOTION ATLAS DANS LES the hexapod configuration to provide motion cues. While widely used, studies have shown that hexapods
Strati cations of hyperelliptic Jacobians and the Sato Grassmannian
Vanhaecke, Pol
Strati#12;cations of hyperelliptic Jacobians and the Sato Grassmannian Pol Vanhaecke Abstract divisors. The strati#12;cation is shown to be related to a natural strati#12;cation on the Sato#12;nite-dimensional Grassmannian, Gr; introduced by Sato (see [SS]). The Grassmannian Gr can be de#12
INTEGRABLE HAMILTONIAN SYSTEM ON THE JACOBIAN OF A SPECTRAL CURVE
construct a variant of Beauville's system whose general level set is isomorphic to the complement completely integrable dynamical system. Its general level set is isomorphic to the complement of the thetaINTEGRABLE HAMILTONIAN SYSTEM ON THE JACOBIAN OF A SPECTRAL CURVE -- AFTER BEAUVILLE REI INOUE
The Jacobian as a measure of planar dose congruence
Paniak, L D
2007-01-01
We propose a new starting point for comparing dose distributions in therapeutic radiation physics using a Jacobian-based measure. The measure is normalization independent, free of tunable parameters, bounded and converges to a unique value when comparing unrelated dose distributions. We present a preliminary demonstration of the sensitivity and general characteristics of this measure.
Point Compression on Jacobians of Hyperelliptic Curves over Fq.
International Association for Cryptologic Research (IACR)
Point Compression on Jacobians of Hyperelliptic Curves over Fq. Colin Stahlke Abstract. Since there space is critical, compression techniques are interesting. In this note we propose a new for decompression is, essentially, computing two square roots in Fq, the cost for compression is much less
MOTIVIC POINCARE SERIES, TORIC SINGULARITIES AND LOGARITHMIC JACOBIAN IDEALS
Paris-Sud XI, UniversitÃ© de
MOTIVIC POINCARÂ´E SERIES, TORIC SINGULARITIES AND LOGARITHMIC JACOBIAN IDEALS H. COBO PABLOS AND P.D. GONZÂ´ALEZ PÂ´EREZ Abstract. The geometric motivic PoincarÂ´e series of a variety, which was introduced the geometric motivic PoincarÂ´e series of S. Similarly, the local geometric motivic PoincarÂ´e series of the germ
A RANDOM MATRIX APPROACH TO MANIPULATOR JACOBIAN Javad Sovizi
Krovi, Venkat
from actu- ator space to joint space). They used neural network method for online compensationA RANDOM MATRIX APPROACH TO MANIPULATOR JACOBIAN Javad Sovizi Automation, Robotics & Mechatronics: javadsov@buffalo.edu Aliakbar Alamdari Venkat N. Krovi Automation, Robotics & Mechatronics Laboratory
New Kinematic Metric for Quantifying Surgical Skill for Flexible Instrument Manipulation
robot with multiple bend- ing sections. The Jacobian operator, which relates the proximal forces applied],[6], animal models, and robotic systems [7]. An- alytical approaches, such as task partitioning [8], kinematics analysis [9], off-line "data mining" to train hidden Markov models [10] or support vector machines
Bonnet, Vincent; Mazzà, Claudia; Fraisse, Philippe; Cappozzo, Aurelio
2013-07-01
This study aimed at the real-time estimation of the lower-limb joint and torso kinematics during a squat exercise, performed in the sagittal plane, using a single inertial measurement unit placed on the lower back. The human body was modeled with a 3-DOF planar chain. The planar IMU orientation and vertical displacement were estimated using one angular velocity and two acceleration components and a weighted Fourier linear combiner. The ankle, knee, and hip joint angles were thereafter obtained through a novel inverse kinematic module based on the use of a Jacobian pseudoinverse matrix and null-space decoupling. The aforementioned algorithms were validated on a humanoid robot for which the mechanical model used and the measured joint angles virtually exhibited no inaccuracies. Joint angles were estimated with a maximal error of 1.5°. The performance of the proposed analytical and experimental methodology was also assessed by conducting an experiment on human volunteers and by comparing the relevant results with those obtained through the more conventional photogrammetric approach. The joint angles provided by the two methods displayed differences equal to 3±1°. These results, associated with the real-time capability of the method, open the door to future field applications in both rehabilitation and sport. PMID:23392337
Comparison of linear forms of the radiative transfer equation with analytic Jacobians.
Huang, Bormin; Smith, William L; Huang, Hung-Lung; Woolf, Harold M
2002-07-20
Determining the Jacobians of the radiative transfer equation (RTE) is important to the qualities of the simultaneous retrieval of geophysical parameters from satellite radiance observations and the assimilation of radiance data into a numerical weather prediction system. Two linear forms of the RTE with analytic Jacobians are formulated. The first linear form has approximate analytic Jacobians, which involves some monochromatic approximation applied to a fast transmittance model. Unlike previous research, which lacks the transmittance Jacobian with respect to the atmospheric temperature profile, this form is complete in the sense that the transmittance Jacobians with respect to atmospheric temperature and absorbing constituent profiles are both present. The second linear form has exact analytic Jacobians derived consistently from the same fast transmittance model without using any monochromatic approximation. By numerical comparison between the two linear forms for the NOAA-12 High-Resolution Infrared Sounder, we show significant errors in the linear form with approximate analytic Jacobians. The relative absolute linearization error from the linear form with approximate analytic Jacobians is shown to be 2-4 orders of magnitude larger than that from the linear form with exact analytic Jacobians, even for the case of a 0.1% perturbation of the U.S. Standard Atmosphere. The errors unnecessarily complicate the ill-posed retrieval problem of atmospheric remote sensing and can be avoided if the correct linear form of the RTE with exact analytic Jacobians is adopted. PMID:12148748
Luanjing Guo; Hai Huang; Derek Gaston; Cody Permann; David Andrs; George Redden; Chuan Lu; Don Fox; Yoshiko Fujita
2013-03-01
Modeling large multicomponent reactive transport systems in porous media is particularly challenging when the governing partial differential algebraic equations (PDAEs) are highly nonlinear and tightly coupled due to complex nonlinear reactions and strong solution-media interactions. Here we present a preconditioned Jacobian-Free Newton-Krylov (JFNK) solution approach to solve the governing PDAEs in a fully coupled and fully implicit manner. A well-known advantage of the JFNK method is that it does not require explicitly computing and storing the Jacobian matrix during Newton nonlinear iterations. Our approach further enhances the JFNK method by utilizing physics-based, block preconditioning and a multigrid algorithm for efficient inversion of the preconditioner. This preconditioning strategy accounts for self- and optionally, cross-coupling between primary variables using diagonal and off-diagonal blocks of an approximate Jacobian, respectively. Numerical results are presented demonstrating the efficiency and massive scalability of the solution strategy for reactive transport problems involving strong solution-mineral interactions and fast kinetics. We found that the physics-based, block preconditioner significantly decreases the number of linear iterations, directly reducing computational cost; and the strongly scalable algebraic multigrid algorithm for approximate inversion of the preconditioner leads to excellent parallel scaling performance.
NASA Astrophysics Data System (ADS)
Guo, Luanjing; Huang, Hai; Gaston, Derek R.; Permann, Cody J.; Andrs, David; Redden, George D.; Lu, Chuan; Fox, Don T.; Fujita, Yoshiko
2013-03-01
Modeling large multicomponent reactive transport systems in porous media is particularly challenging when the governing partial differential algebraic equations (PDAEs) are highly nonlinear and tightly coupled due to complex nonlinear reactions and strong solution-media interactions. Here we present a preconditioned Jacobian-Free Newton-Krylov (JFNK) solution approach to solve the governing PDAEs in a fully coupled and fully implicit manner. A well-known advantage of the JFNK method is that it does not require explicitly computing and storing the Jacobian matrix during Newton nonlinear iterations. Our approach further enhances the JFNK method by utilizing physics-based, block preconditioning and a multigrid algorithm for efficient inversion of the preconditioner. This preconditioning strategy accounts for self- and optionally, cross-coupling between primary variables using diagonal and off-diagonal blocks of an approximate Jacobian, respectively. Numerical results are presented demonstrating the efficiency and massive scalability of the solution strategy for reactive transport problems involving strong solution-mineral interactions and fast kinetics. We found that the physics-based, block preconditioner significantly decreases the number of linear iterations, directly reducing computational cost; and the strongly scalable algebraic multigrid algorithm for approximate inversion of the preconditioner leads to excellent parallel scaling performance.
Fast computation of complete elliptic integrals and Jacobian elliptic functions
Toshio Fukushima
2009-01-01
As a preparation step to compute Jacobian elliptic functions efficiently, we created a fast method to calculate the complete\\u000a elliptic integral of the first and second kinds, K(m) and E(m), for the standard domain of the elliptic parameter, 0 m m < 0.9, the method utilizes 10 pairs of approximate polynomials of the order of 9–19 obtained by truncating Taylor series
Jacobian-free Newton-Krylov methods: a survey of approaches and applications
D. A. Knoll; D. E. Keyes
2004-01-01
Jacobian-free Newton-Krylov (JFNK) methods are synergistic combinations of Newton-type methods for super- linearly convergent solution of nonlinear equations and Krylov subspace methods for solving the Newton correction equations. The link between the two methods is the Jacobian-vector product, which may be probed approximately without forming and storing the elements of the true Jacobian, through a variety of means. Various approximations
Jacobian-free Newton–Krylov methods: a survey of approaches and applications
D. A. Knoll; D. E. Keyes
2004-01-01
Jacobian-free Newton–Krylov (JFNK) methods are synergistic combinations of Newton-type methods for superlinearly convergent solution of nonlinear equations and Krylov subspace methods for solving the Newton correction equations. The link between the two methods is the Jacobian-vector product, which may be probed approximately without forming and storing the elements of the true Jacobian, through a variety of means. Various approximations to
Jacobian-free Newton-Krylov methods: a survey of approaches and applications
D. A. Knoll; D. E. Keyes
2004-01-01
Jacobian-free Newton-Krylov (JFNK) methods are synergistic combinations of Newton-type methods for superlinearly convergent solution of nonlinear equations and Krylov subspace methods for solving the Newton correction equations. The link between the two methods is the Jacobian-vector product, which may be probed approximately without forming and storing the elements of the true Jacobian, through a variety of means. Various approximations to
Prejean, S.; Ellsworth, W.; Zoback, M.; Waldhauser, F.
2002-01-01
We have determined high-resolution hypocenters for 45,000+ earthquakes that occurred between 1980 and 2000 in the Long Valley caldera area using a double-difference earthquake location algorithm and routinely determined arrival times. The locations reveal numerous discrete fault planes in the southern caldera and adjacent Sierra Nevada block (SNB). Intracaldera faults include a series of east/west-striking right-lateral strike-slip faults beneath the caldera's south moat and a series of more northerly striking strike-slip/normal faults beneath the caldera's resurgent dome. Seismicity in the SNB south of the caldera is confined to a crustal block bounded on the west by an east-dipping oblique normal fault and on the east by the Hilton Creek fault. Two NE-striking left-lateral strike-slip faults are responsible for most seismicity within this block. To understand better the stresses driving seismicity, we performed stress inversions using focal mechanisms with 50 or more first motions. This analysis reveals that the least principal stress direction systematically rotates across the studied region, from NE to SW in the caldera's south moat to WNW-ESE in Round Valley, 25 km to the SE. Because WNW-ESE extension is characteristic of the western boundary of the Basin and Range province, caldera area stresses appear to be locally perturbed. This stress perturbation does not seem to result from magma chamber inflation but may be related to the significant (???20 km) left step in the locus of extension along the Sierra Nevada/Basin and Range province boundary. This implies that regional-scale tectonic processes are driving seismic deformation in the Long Valley caldera.
Shotput kinematics made simple
NASA Astrophysics Data System (ADS)
Faella, O.; De Luca, R.
2013-11-01
We show that some results in the kinematics of a point particle can be easily recalled by introducing simple definitions. In particular, in the parabolic motion of a particle thrown from a height h above the origin O at an angle ? from the horizontal direction, the optimum angle ?* for reaching the maximum distance Rmax on the ground, measured from the origin, can be found by calculating the inverse tangent of the ratio between the initial velocity V0 and the final velocity Vf. The value of Rmax is itself found to be easily expressed as V0Vf/g, g being the acceleration due to gravity.
Learning Kinematics from Direct Self-Observation using Nearest-Neighbor
Cremers, Daniel
Learning Kinematics from Direct Self-Observation using Nearest-Neighbor Methods Hannes Schulz, Lionel Ott, J¨urgen Sturm and Wolfram Burgard Abstract Commonly, the inverse kinematic function robot to estimate the inverse kinematic function on-the-fly directly from self-observation and without
Hicks, H.R.; Dory, R.A.; Holmes, J.A.
1983-01-01
We illustrate in some detail a 2D inverse-equilibrium solver that was constructed to analyze tokamak configurations and stellarators (the latter in the context of the average method). To ensure that the method is suitable not only to determine equilibria, but also to provide appropriately represented data for existing stability codes, it is important to be able to control the Jacobian, tilde J is identical to delta(R,Z)/delta(rho, theta). The form chosen is tilde J = J/sub 0/(rho)R/sup l/rho where rho is a flux surface label, and l is an integer. The initial implementation is for a fixed conducting-wall boundary, but the technique can be extended to a free-boundary model.
Luanjing Guo; Chuan Lu; Hai Huang; Derek R. Gaston
2012-06-01
Systems of multicomponent reactive transport in porous media that are large, highly nonlinear, and tightly coupled due to complex nonlinear reactions and strong solution-media interactions are often described by a system of coupled nonlinear partial differential algebraic equations (PDAEs). A preconditioned Jacobian-Free Newton-Krylov (JFNK) solution approach is applied to solve the PDAEs in a fully coupled, fully implicit manner. The advantage of the JFNK method is that it avoids explicitly computing and storing the Jacobian matrix during Newton nonlinear iterations for computational efficiency considerations. This solution approach is also enhanced by physics-based blocking preconditioning and multigrid algorithm for efficient inversion of preconditioners. Based on the solution approach, we have developed a reactive transport simulator named RAT. Numerical results are presented to demonstrate the efficiency and massive scalability of the simulator for reactive transport problems involving strong solution-mineral interactions and fast kinetics. It has been applied to study the highly nonlinearly coupled reactive transport system of a promising in situ environmental remediation that involves urea hydrolysis and calcium carbonate precipitation.
Kinematics of the six-degree-of-freedom force-reflecting Kraft Master
NASA Technical Reports Server (NTRS)
Williams, Robert L., II
1991-01-01
Presented here are kinematic equations for a six degree of freedom force-reflecting hand controller. The forward kinematics solution is developed and shown in simplified form. The Jacobian matrix, which uses terms from the forward kinematics solution, is derived. Both of these kinematic solutions require joint angle inputs. A calibration method is presented to determine the hand controller joint angles given the respective potentiometer readings. The kinematic relationship describing the mechanical coupling between the hand and controller shoulder and elbow joints is given. These kinematic equations may be used in an algorithm to control the hand controller as a telerobotic system component. The purpose of the hand controller is two-fold: operator commands to the telerobotic system are entered using the hand controller, and contact forces and moments from the task are reflected to the operator via the hand controller.
Kinematics and control of redundant robotic arm based on dielectric elastomer actuators
NASA Astrophysics Data System (ADS)
Branz, Francesco; Antonello, Andrea; Carron, Andrea; Carli, Ruggero; Francesconi, Alessandro
2015-04-01
Soft robotics is a promising field and its application to space mechanisms could represent a breakthrough in space technologies by enabling new operative scenarios (e.g. soft manipulators, capture systems). Dielectric Elastomers Actuators have been under deep study for a number of years and have shown several advantages that could be of key importance for space applications. Among such advantages the most notable are high conversion efficiency, distributed actuation, self-sensing capability, multi-degree-of-freedom design, light weight and low cost. The big potentialities of double cone actuators have been proven in terms of good performances (i.e. stroke and force/torque), ease of manufacturing and durability. In this work the kinematic, dynamic and control design of a two-joint redundant robotic arm is presented. Two double cone actuators are assembled in series to form a two-link design. Each joint has two degrees of freedom (one rotational and one translational) for a total of four. The arm is designed to move in a 2-D environment (i.e. the horizontal plane) with 4 DoF, consequently having two degrees of redundancy. The redundancy is exploited in order to minimize the joint loads. The kinematic design with redundant Jacobian inversion is presented. The selected control algorithm is described along with the results of a number of dynamic simulations that have been executed for performance verification. Finally, an experimental setup is presented based on a flexible structure that counteracts gravity during testing in order to better emulate future zero-gravity applications.
Direct calculation of the electrode movement Jacobian for 3D EIT Camille Gomez-Laberge
Adler, Andy
Direct calculation of the electrode movement Jacobian for 3D EIT Camille GÂ´omez-Laberge 1 and Andy on an indirect perturbation Jacobian calculation, involving the re-computation of the forward solution. Although the computation time grows rapidly for large 3D problems. We propose an efficient, novel method of calculating
M. Jerosolimski; L. Levacher
1994-01-01
Many numerical methods used in power system simulation require the computation of Jacobian matrices. This being particularly true for implicit integration algorithms, and not for explicit ones. These computations often take a significant proportion of the overall CPU time. This paper presents an application of the automatic differentiation method which results in large savings in the computation of Jacobian matrices.
A Jacobian-free NewtonKrylov algorithm for compressible turbulent fluid flows
Zingg, David W.
A Jacobian-free NewtonKrylov algorithm for compressible turbulent fluid flows Todd T. Chisholm Inc. All rights reserved. 1. Introduction Jacobian-free NewtonKrylov (JFNK) methods are becoming increasingly popular in many branches of computational physics, Jaco- bian-free NewtonKrylov (JFNK) methods
Constructing pairing-friendly genus 2 curves over prime fields with ordinary Jacobians
International Association for Cryptologic Research (IACR)
Constructing pairing-friendly genus 2 curves over prime fields with ordinary Jacobians David explicit construction of genus 2 curves over finite fields whose Jacobians are ordinary, have large prime-order subgroups, and have small embedding degree. Our algorithm works for arbitrary embedding degrees k and prime
Li, Yangmin
Hybrid Kinematics and Stability Analysis for the Mobile Modular Manipulator Yangmin Li and Yugang.mo} Abstract This paper addresses the following issues: how to build the hybrid kinematics model kinematics. The inverse kinematics analysis solves the task-decomposing problem mentioned above. Dynamic
KINEMATIC MODELING OF STEWART-GOUGH PLATFORMS Pedro Cruz, Ricardo Ferreira
Instituto de Sistemas e Robotica
KINEMATIC MODELING OF STEWART-GOUGH PLATFORMS Pedro Cruz, Ricardo Ferreira Institute for Systems jseq@isr.ist.utl.pt Keywords: Parallel robots, Direct kinematics, Inverse kinematics. Abstract: This paper describes a method to solve the direct kinematics of a generic Stewart-Gough manipulators
Kinematics and Dexterity Analysis for a Novel 3-DOF Translational Parallel Manipulator
Li, Yangmin
Kinematics and Dexterity Analysis for a Novel 3-DOF Translational Parallel Manipulator Yangmin Li. The inverse kinematics, forward kinematics, and velocity analysis are performed and the singularity problems layout angles of a general 3-PRC TPM are designed. Index Terms-- Parallel mechanism; Kinematics; Singular
NSDL National Science Digital Library
2014-03-10
In this activity, learners are challenged to design and build a system of gears and kinematics to create a hand-stamping machine. In this activity, learners get a chance to design, build, and test an automated hand-stamping machine by borrowing concepts from existing designs and modifying them to fit their needs. They'll gain experience using gears and pulleys to explore concepts such as mechanical advantage, changing from rotary to linear motion, and altering timing in a machine.
MORAL KINEMATICS 1 Running head: MORAL KINEMATICS
Reber, Paul J.
MORAL KINEMATICS 1 Running head: MORAL KINEMATICS Iliev, R., Sachdeva, S., & Medin, D. (2012) Moral kinematics: The role of physical factors in moral judgments. Memory and Cognition. Online. DOI 10.3758/s13421-012-0217-1 Moral Kinematics: the Role of Physical Factors on Moral Judgments Rumen I Iliev*, Sonya Sachdeva
AGN Kinematics BLR profiles and kinematics
Crenshaw, Michael
1 AGN Kinematics · BLR profiles and kinematics · Outflows seen in Absorption (AGN Winds) · Emission-Line Outflows in the NLR · Combined Absorber and NLR Outflows Studies #12;2 BLR Profiles and Kinematics of NLR) -Wings are logarithmic, but many kinematic models can reproduce them (Capriotti, et al. 1990, Ap
NASA Astrophysics Data System (ADS)
Kamei, R.; Pratt, R. G.
2013-12-01
Visco-acoustic waveform inversion can potentially yield quantitative images of the distribution of both velocity and the attenuation parameters from seismic data. Simultaneous inversion of velocity and attenuation tend to cause significant ';cross-talk' between the resulting images, reflecting a lack of parameter resolution and indicating the need for pre-conditioning and regularization of the inverse problem.We analyse the cross-talk issue by partitioning the inversion parameters into two classes; the velocity parameter class, and the attenuation parameter class. Both parameters are defined at a reference frequency, and a dispersion relation is assumed that describes these parameters at any other frequency. We formulate the model gradient of the objective function at a forward modelling frequency, and convert them to the reference frequency by employing the Jacobian of the coordinate change represented by the dispersion relation. At a given modelling frequency, the Frechet derivatives corresponding to these two parameter classes differ only by a 90 degree phase shift, meaning that the magnitudes of resulting model updates will be unscaled, and will not reflect the expected magnitudes in realistic (Q>>1) media. Due to the lack of scaling, cross-talk will be enhanced by poor subsurface illumination, by errors in kinematics, and by data noise. Initial results from a suite of synthetic cross-hole tests using a three-layer randomly heterogenous model with both intrinsic and extrinsic (scattering) attenuation demonstrate that cross-talk is a significant problem in attenuation inversion. Using the same model, we further show that cross-talk can be suppressed by varying the attenuation scaling term in our pre-conditioning operator. This strategy is effective for simultaneous inversion of velocity and attenuation, and for sequential inversion (a two-stage approach in which only the velocity models are recovered in the first stage). Further regularization using a smoothing term applied to the attenuation parameters is also effective in reducing cross-talk, which is often highly oscillatory. The sequential inversion approach restricts the search space for attenuation parameters, and appears to be helpful in retrieving a reliable attenuation model.
Approximating Human Reaching Volumes Using Inverse Kinematics
Rodríguez, Inmaculada
Henares, Madrid, Spain b Virtual Reality Laboratory. Swiss Federal Institute of Technology. Lausanne. Introduction Virtual Humans are a valuable medium for gaining knowledge and understanding about the human body to the research on topics related with humans. Handicapped persons, ancient or injured people may have limited
Inverse differential kinematics Statics and force transformations
De Luca, Alessandro
= " (end- effector close to the origin), despite the required Cartesian displacement is small Robotics 1 4 motion start q = J-1 (q) v . constant v #12;Simulation results planar 2R robot in straight line Cartesian in straight line Cartesian motion Robotics 1 6 path at #=170° regular case q1 q2 error due only to numerical
NASA Astrophysics Data System (ADS)
Fielding, E. J.; Wei, S.; Leprince, S.; Sladen, A.; Simons, M.; Avouac, J.; Briggs, R. W.; Hudnut, K. W.; Helmberger, D. V.; Hensley, S.; Hauksson, E.; Gonzalez-Garcia, J. J.; Herring, T.; Akciz, S. O.
2010-12-01
We use interferometric analysis of synthetic aperture radar (SAR) images (InSAR) and pixel tracking by subpixel correlation of SAR and optical images to map the fault ruptures and surface deformation of the 4 April 2010 El Mayor-Cucapah earthquake (Mw 7.2) in Baja California, Mexico. We then combine sampled InSAR and subpixel correlation results with GPS offsets at PBO stations and teleseismic waveforms in a joint inversion to produce a kinematic fault slip model. Pixel-tracking measurements from SPOT 2.5 m panchromatic images and from Envisat ASAR and ALOS PALSAR images measure large ground displacements close to fault ruptures, with a strong discontinuity where the rupture reached the surface. Optical image subpixel correlation measures horizontal displacements in both the east-west and north-south directions and shows the earthquake ruptured the Pescadores Fault in the southern Sierra Cucapah and the Borrego Fault in the central and northern edge of the mountain range. At the south end of the Sierra Cucapah, the fault ruptures fork into two subparallel strands with substantial slip on both visible. SAR image subpixel correlation measures horizontal deformation in the along-track direction of the satellite (approximately north or south) and in the radar line-of-sight direction. SAR along-track offsets, especially on ALOS images, show that there is a large amount of right-lateral slip (1-3 m) on a previously unmapped system of faults extending about 60 km to the southeast of the epicenter beneath the Colorado River Delta named the Indiviso Fault system. Aftershocks also extend approximately the same distance to the southeast. InSAR analyses of Envisat, ALOS and UAVSAR images, measure the surface displacements in the same radar line-of-sight as the range pixel tracking, but with much greater precision. Combination of SAR images from different directions allows the separation of the vertical and east components of the deformation, revealing the large normal fault slip in the Sierra Cucapah (down to the east) and blocks with substantial vertical motion in the Delta (both down to the east and down to the west). Kinematic finite fault modeling shows a bilateral rupture with fault slip shallower than 10 km on the faults to the NW and SE of the epicenter. The InSAR also reveals slip on many minor faults on both sides of the Sierra Cucapah and to the northwest, with displacements of cm to 10’s of cm. High-resolution UAVSAR coseismic and postseismic interferograms revealed triggered slip on a number of faults in the Yuha desert and Salton Trough, with some slip occurring in the three months after the main shock. Postseismic InSAR shows rapid afterslip on shallow faults at the north and south ends of the main coseismic rupture. Areas of the Colorado River Delta that subsided during the main earthquake continued to subside afterwards. Larger spatial scales of postseismic deformation that would be expected from viscoelastic relaxation are difficult to measure in the InSAR data because of large variations in tropospheric water vapor.
Kinematic functions for the 7 DOF robotics research arm
NASA Technical Reports Server (NTRS)
Kreutz, K.; Long, M.; Seraji, Homayoun
1989-01-01
The Robotics Research Model K-1207 manipulator is a redundant 7R serial link arm with offsets at all joints. To uniquely determine joint angles for a given end-effector configuration, the redundancy is parameterized by a scalar variable which corresponds to the angle between the manipulator elbow plane and the vertical plane. The forward kinematic mappings from joint-space to end-effector configuration and elbow angle, and the augmented Jacobian matrix which gives end-effector and elbow angle rates as a function of joint rates, are also derived.
(inverse kinematics) (inverse dynamics) (PCA : principle component analysis)
Lee, In-Kwon
-based motion blending Woojun Jung 0 , In-Kwon Lee Visual Computing Lab. Department of Computer Science Yonsei. [2] M. Alexa, W. Mueller. Representing animations by principal components. Computer Graphics Forum. Fua. Style-based motion synthesis. Computer Graphics Forum. 23. 4. pp. 799~812. 2004. [7] J. Barbi , A
Low-rank Quasi-Newton updates for Robust Jacobian lagging in Newton methods
Brown, J.; Brune, P. [Mathematics and Computer Science Division, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439 (United States)
2013-07-01
Newton-Krylov methods are standard tools for solving nonlinear problems. A common approach is to 'lag' the Jacobian when assembly or preconditioner setup is computationally expensive, in exchange for some degradation in the convergence rate and robustness. We show that this degradation may be partially mitigated by using the lagged Jacobian as an initial operator in a quasi-Newton method, which applies unassembled low-rank updates to the Jacobian until the next full reassembly. We demonstrate the effectiveness of this technique on problems in glaciology and elasticity. (authors)
Solving Nonlinear Solid Mechanics Problems with the Jacobian-Free Newton Krylov Method
J. D. Hales; S. R. Novascone; R. L. Williamson; D. R. Gaston; M. R. Tonks
2012-06-01
The solution of the equations governing solid mechanics is often obtained via Newton's method. This approach can be problematic if the determination, storage, or solution cost associated with the Jacobian is high. These challenges are magnified for multiphysics applications with many coupled variables. Jacobian-free Newton-Krylov (JFNK) methods avoid many of the difficulties associated with the Jacobian by using a finite difference approximation. BISON is a parallel, object-oriented, nonlinear solid mechanics and multiphysics application that leverages JFNK methods. We overview JFNK, outline the capabilities of BISON, and demonstrate the effectiveness of JFNK for solid mechanics and solid mechanics coupled to other PDEs using a series of demonstration problems.
Neurofuzzy Inverse Jacobian Mapping for Multi-Finger Robot Hand Control
E. A. Al-gallaf
2004-01-01
Fuzzy systems and models are useful for describing processes where the underlying physical mechanisms are not completely known and where a system behavior is understood in qualitative terms. Neurofuzzy systems have been employed in large number of intelligent based control systems and robotics, that is due to the ability to deal with large number of inputs and with the ability
Jacobian Adaptation of HMM with Initial Model Selection for Noisy Speech Recognition
Shimodaira, Hiroshi; Kato, Yukata; Akae, Toshihiko; Nakai, Mitsuru; Sagayama, Shigeki
An extension of Jacobian Adaptation (JA) of HMMs for degraded speech recognition is presented in which appropriate set of initial models is selected from a number of initial-model sets designed for different noise environments. Based on the first...
Motivic interpretation of Milnor K-groups attached to Jacobian varieties
Motivic interpretation of Milnor K-groups attached to Jacobian varieties-(k) . Key words: motivic cohomology, 1-motives, Milnor K-groups, Weil reciprocity law Contents 0, the University of Tokyo. 1 #12; 4 Motivic cohomology groups attached
Fully-implicit Jacobian-free Newton-Krylov Solvers for the nonhydrostatic Euler equations
J. F. Kelly; F. Giraldo; L. Carr
2009-01-01
For most atmospheric flows, gravity and acoustic waves are the fastest waves in the system. These fast waves severely restrict the time-step in the explicit integration of the non-hydrostatic compressible Euler equations. To circumvent this problem, a fully-implicit time-integrator is proposed using the Jacobian-Free Newton Krylov (JFNK) framework. Since forming and storing the Jacobian matrix is computationally expensive, JFNK methods
A Framework to Illustrate Kinematic Behavior of Mechanisms by Haptic Feedback
Zhang, Qinqin; Bennis, Fouad; Zhang, Wei
2007-01-01
The kinematic properties of mechanisms are well known by the researchers and teachers. The theory based on the study of Jacobian matrices allows us to explain, for example, the singular configuration. However, in many cases, the physical sense of such properties is difficult to explain to students. The aim of this article is to use haptic feedback to render to the user the signification of different kinematic indices. The framework uses a Phantom Omni and a serial and parallel mechanism with two degrees of freedom. The end-effector of both mechanisms can be moved either by classical mouse, or Phantom Omni with or without feedback.
Gou, Kun 1981-
2012-11-15
. They are then employed to reconstruct the shear modulus and residual stress in a nonlinear approach by inverse spectral techniques. The shear modulus is recovered by a multidimensional secant method (MSM). The MSM avoids computing the Jacobian matrix of the equations...
REDBACK: opensource software for efficient noisereduction in plate kinematic reconstructions
Bodin, Thomas
REDBACK: opensource software for efficient noisereduction in plate kinematic reconstructions G University, as part of the AuScopeAGOS Inversion Labora- tory. REDBACK is released opensource under the GNU kinematics inferred from hightemporalresolution finiterotation data sets. We describe REDBACK, an opensource
Modal kinematics for multisection continuum arms.
Godage, Isuru S; Medrano-Cerda, Gustavo A; Branson, David T; Guglielmino, Emanuele; Caldwell, Darwin G
2015-06-01
This paper presents a novel spatial kinematic model for multisection continuum arms based on mode shape functions (MSF). Modal methods have been used in many disciplines from finite element methods to structural analysis to approximate complex and nonlinear parametric variations with simple mathematical functions. Given certain constraints and required accuracy, this helps to simplify complex phenomena with numerically efficient implementations leading to fast computations. A successful application of the modal approximation techniques to develop a new modal kinematic model for general variable length multisection continuum arms is discussed. The proposed method solves the limitations associated with previous models and introduces a new approach for readily deriving exact, singularity-free and unique MSF's that simplifies the approach and avoids mode switching. The model is able to simulate spatial bending as well as straight arm motions (i.e., pure elongation/contraction), and introduces inverse position and orientation kinematics for multisection continuum arms. A kinematic decoupling feature, splitting position and orientation inverse kinematics is introduced. This type of decoupling has not been presented for these types of robotic arms before. The model also carefully accounts for physical constraints in the joint space to provide enhanced insight into practical mechanics and impose actuator mechanical limitations onto the kinematics thus generating fully realizable results. The proposed method is easily applicable to a broad spectrum of continuum arm designs. PMID:25969947
A Kinematic Model of the Human Arm Using Triangular B'ezier Spline Surfaces
Gallier, Jean
A Kinematic Model of the Human Arm Using Triangular B'ezier Spline Surfaces Deepak Tolani, Norman Philadelphia, PA 19104, USA jean@saul.cis.upenn.edu March 15, 2000 Abstract. This paper presents a kinematic surface. It is also explained how this model is used for solving forward and inverse kinematics
Kinematic analysis of pre-grasp configurations for generalized dexterous hands
Pinto, Victor Hugo
1990-01-01
. The major linkage controls the end effector position and the minor linkage changes the end effector orientation. Furthermore, most iterative techniques utilize the manipulator Jacobian, as in Goldenberg, Benhabib, and Fenton (1985). A necessary condition... ill-conditioned [6]. Goldenberg, Benhabib, and Fenton overcome the problem of singularities by utilizing the generalized inverse, or pseudoinverse. A knowledge ? based solution using neural networks is proposed by Guez and Ziauddin (1988...
Total Nuclear Variation and Jacobian Extensions of Total Variation for Vector Fields.
Holt, Kevin
2014-06-23
We explore a class of vectorial total variation (VTV) measures formed as the spatial sum of a pixel-wise matrix norm of the Jacobian of a vector field. We give a theoretical treatment that indicates that, while color smearing and affine-coupling bias (often reported as gray-scale bias) are typically cited as drawbacks for VTV, these are actually fundamental to smoothing vector direction (i.e. smoothing hue and saturation in color images). Additionally, we show that encouraging different vector channels to share a common gradient direction is equivalent to minimizing Jacobian rank. We thus propose Total Nuclear Variation (TNV), and since nuclear norm is the convex envelope of matrix rank, we argue that TNV is the optimal convex regularizer for enforcing shared directions. We also propose extended Jacobians, which use larger neighborhoods than the conventional finite difference operator, and we discuss efficient VTV optimization algorithms. In simple color image denoising experiments, TNV outperformed other common VTV regularizers, and was further improved by using extended Jacobians. TNV was also competitive with the method of non-local means, often outperforming it by 0.25 to 2 dB when using extended Jacobians. PMID:24968168
Principal Component Geostatistical Approach for large-dimensional inverse problems
Kitanidis, P K; Lee, J
2014-01-01
The quasi-linear geostatistical approach is for weakly nonlinear underdetermined inverse problems, such as Hydraulic Tomography and Electrical Resistivity Tomography. It provides best estimates as well as measures for uncertainty quantification. However, for its textbook implementation, the approach involves iterations, to reach an optimum, and requires the determination of the Jacobian matrix, i.e., the derivative of the observation function with respect to the unknown. Although there are elegant methods for the determination of the Jacobian, the cost is high when the number of unknowns, m, and the number of observations, n, is high. It is also wasteful to compute the Jacobian for points away from the optimum. Irrespective of the issue of computing derivatives, the computational cost of implementing the method is generally of the order of m2n, though there are methods to reduce the computational cost. In this work, we present an implementation that utilizes a matrix free in terms of the Jacobian matrix Gauss-Newton method and improves the scalability of the geostatistical inverse problem. For each iteration, it is required to perform K runs of the forward problem, where K is not just much smaller than m but can be smaller that n. The computational and storage cost of implementation of the inverse procedure scales roughly linearly with m instead of m2 as in the textbook approach. For problems of very large m, this implementation constitutes a dramatic reduction in computational cost compared to the textbook approach. Results illustrate the validity of the approach and provide insight in the conditions under which this method perform best. PMID:25558113
Principal Component Geostatistical Approach for large-dimensional inverse problems
NASA Astrophysics Data System (ADS)
Kitanidis, P. K.; Lee, J.
2014-07-01
The quasi-linear geostatistical approach is for weakly nonlinear underdetermined inverse problems, such as Hydraulic Tomography and Electrical Resistivity Tomography. It provides best estimates as well as measures for uncertainty quantification. However, for its textbook implementation, the approach involves iterations, to reach an optimum, and requires the determination of the Jacobian matrix, i.e., the derivative of the observation function with respect to the unknown. Although there are elegant methods for the determination of the Jacobian, the cost is high when the number of unknowns, m, and the number of observations, n, is high. It is also wasteful to compute the Jacobian for points away from the optimum. Irrespective of the issue of computing derivatives, the computational cost of implementing the method is generally of the order of m2n, though there are methods to reduce the computational cost. In this work, we present an implementation that utilizes a matrix free in terms of the Jacobian matrix Gauss-Newton method and improves the scalability of the geostatistical inverse problem. For each iteration, it is required to perform K runs of the forward problem, where K is not just much smaller than m but can be smaller that n. The computational and storage cost of implementation of the inverse procedure scales roughly linearly with m instead of m2 as in the textbook approach. For problems of very large m, this implementation constitutes a dramatic reduction in computational cost compared to the textbook approach. Results illustrate the validity of the approach and provide insight in the conditions under which this method perform best.
Dana A. Knoll; Kord Smith
2011-01-01
The use of the Jacobian-free Newton-Krylov (JFNK) method within the context of nonlinear diffusion acceleration (NDA) of source iteration is explored. The JFNK method is a synergistic combination of Newton's method as the nonlinear solver and Krylov methods as the linear solver. JFNK methods do not form or store the Jacobian matrix, and Newton's method is executed via probing the
Using ADIFOR and ADIC to provide Jacobians for the SNES component of PETSc
Wu, Po-Ting; Bischof, C.H.; Hovland, P.D.
1997-11-01
The solution of large-scale nonlinear problems is important to many areas of computational science. The SNES component of PETSc provides a robust and flexible suite of numerical routines for the solving such problems. These routines generally utilize the Jacobian matrix. We present a strategy for using ADIFOR or ADIC to assist in the development of a subroutine for computing this matrix. We illustrate this strategy using one of the PETSc example programs and four different approaches to computing the Jacobian via automatic differentiation.
Fisher Information for Inverse Problems and Trace Class Operators
Sven Nordebo; Mats Gustafsson; Andrei Khrennikov; Bö rje Nilsson; Joachim Toft
2012-03-24
This paper provides a mathematical framework for Fisher information analysis for inverse problems based on Gaussian noise on infinite-dimensional Hilbert space. The covariance operator for the Gaussian noise is assumed to be trace class, and the Jacobian of the forward operator Hilbert-Schmidt. We show that the appropriate space for defining the Fisher information is given by the Cameron-Martin space. This is mainly because the range space of the covariance operator always is strictly smaller than the Hilbert space. For the Fisher information to be well-defined, it is furthermore required that the range space of the Jacobian is contained in the Cameron-Martin space. In order for this condition to hold and for the Fisher information to be trace class, a sufficient condition is formulated based on the singular values of the Jacobian as well as of the eigenvalues of the covariance operator, together with some regularity assumptions regarding their relative rate of convergence. An explicit example is given regarding an electromagnetic inverse source problem with "external" spherically isotropic noise, as well as "internal" additive uncorrelated noise.
Advanced Kinematics Lecture Notes
Hayes, John
MECH 5507 Advanced Kinematics Lecture Notes M.J.D. Hayes September 4, 2005 #12;2 #12;Chapter 1 relative configuration changes with time. Dynamics, in turn, has two main components: kinematics and kinetics. Kinematics: The study of motion, without considering the forces causing the motion: position
NASA Astrophysics Data System (ADS)
Fujii, Fumio; Yamakawa, Yuki; Noguchi, Hirohisa
2010-07-01
In the previous publications of the authors, an eigenanalysis-free computational procedure has been proposed to extract the bifurcation buckling mode(s) from the LDL T -decomposed symmetric stiffness matrix in the vicinity of a stability point. Any eigensolver, for instance, inverse iteration or subspace method, is not necessary. The procedure has been verified in numerical examples and well works in multiple and clustered bifurcation problems too. This present paper will extend the eigenanalysis-free procedure to the LDU-decomposed non-symmetric Jacobian matrix, from which both left and right critical eigenvectors relevant to the stability point may be extracted in a similar way. The idea is mathematical and totally independent of the physical problem to be solved, so that it is applicable to any non-symmetric square matrix in stability problems including plasticity with non-associated flow rules, contact and fluid-structure interaction. The linear-algebraic background of non-symmetric eigenvalue problems is firstly described. The present paper will then mention the role play of the left and right critical eigenvectors in stability analysis and the eigenanalysis-free LDU-procedure is proposed. Numerical examples of elastoplastic bifurcation are illustrated for verification and discussion. In APPENDICES, a bench model visualizes the mechanical meaning of the left and right critical singular vectors of a rectangular matrix.
NSDL National Science Digital Library
David Smith
Using Mathcad, Maple, Mathmatica, or MatLab, learner should be able to review concepts of inverse functions, and to use those concepts, together with functions defined by integrals, to develop inverse trigonometric functions.
3D-marine tCSEM inversion using model reduction in the Rational Krylov subspace
NASA Astrophysics Data System (ADS)
Sommer, M.; Jegen, M. D.
2014-12-01
Computationally, the most expensive part of a 3D time domain CSEM inversion is the computation of the Jacobian matrix in every Gauss-Newton step. An other problem is its size for large data sets. We use a model reduction method (Zaslavsky et al, 2013), that compresses the Jacobian by projecting it with a Rational Krylov Subspace (RKS). It also reduces the runtime drastically, compared to the most common adjoint approach and was implemented on GPU.It depends on an analytic derivation of the implicit Anzatz function, which solves Maxwell's diffusion equation in the Eigenspace giving a Jacobian dependent on the Eigenpairs and its derivatives of the forward problem. The Eigenpairs are approximated by Ritz-pairs in the Rational Krylov subspace. Determination of the derivived Ritz-pairs is the most time consuming and was fully GPU-optimized. Furthermore, the amount of inversion cells is reduced by using Octree meshes. The gridding allows for the incorporation of complicated survey geometries, as they are encountered in marine CSEM datasets.As a first result, the Jacobian computation is, even on a Desktop, faster than the most common adjoint approach on a super computer for realistic data sets. We will present careful benchmarking and accuracy tests of the new method and show how it can be applied to a real marine scenario.
Integer solutions of integral inequalities and H-invariant Jacobian Poisson structures
Giovanni Ortenzi; Vladimir Rubtsov; Serge Roméo Tagne Pelap
2011-03-22
We study the Jacobian Poisson structures in any dimension invariant with respect to the discrete Heisenberg group. The classification problem is related to the discrete volume of suitable solids. Particular attention is given to dimension 3 whose simplest example is the Artin-Schelter-Tate Poisson tensors respectively.
Flux Jacobian matrices and generaled Roe average for an equilibrium real gas
NASA Technical Reports Server (NTRS)
Vinokur, Marcel
1988-01-01
Inviscid flux Jacobian matrices and their properties used in numerical solutions of conservation laws are extended to general, equilibrium gas laws. Exact and approximate generalizations of the Roe average are presented. Results are given for one-dimensional flow, and then extended to three-dimensional flow with time-varying grids.
GENERALISED HEEGNER CYCLES AND INTERMEDIATE JACOBIANS OF KUGA-SATO VARIETIES I
Goren, Eyal Z.
GENERALISED HEEGNER CYCLES AND INTERMEDIATE JACOBIANS OF KUGA-SATO VARIETIES I HENRI DARMON (NOTES cycles on Kuga-Sato varieties and similar varieties. Before introducing the cycles we are interested in, and Smithling. In this classical case, we have some integer r 0 and the 2r-th Kuga-Sato variety W2r that can
NASA Astrophysics Data System (ADS)
Zhang, Xiaofeng
2012-03-01
Image formation in fluorescence diffuse optical tomography is critically dependent on construction of the Jacobian matrix. For clinical and preclinical applications, because of the highly heterogeneous characteristics of the medium, Monte Carlo methods are frequently adopted to construct the Jacobian. Conventional adjoint Monte Carlo method typically compute the Jacobian by multiplying the photon density fields radiated from the source at the excitation wavelength and from the detector at the emission wavelength. Nonetheless, this approach assumes that the source and the detector in Green's function are reciprocal, which is invalid in general. This assumption is particularly questionable in small animal imaging, where the mean free path length of photons is typically only one order of magnitude smaller than the representative dimension of the medium. We propose a new method that does not rely on the reciprocity of the source and the detector by tracing photon propagation entirely from the source to the detector. This method relies on the perturbation Monte Carlo theory to account for the differences in optical properties of the medium at the excitation and the emission wavelengths. Compared to the adjoint methods, the proposed method is more valid in reflecting the physical process of photon transport in diffusive media and is more efficient in constructing the Jacobian matrix for densely sampled configurations.
Jacobian Singularities in Optimal Power Flow Problems Caused by Intertemporal Constraints
Li, Xin
Jacobian Singularities in Optimal Power Flow Problems Caused by Intertemporal Constraints Kyri, Senior Member, IEEE. Abstract--In multi-timestep Optimal Power Flow (OPF) for- mulations, constraints on the Newton-Raphson al- gorithm are widely used to solve Optimal Power Flow (OPF) and Economic Dispatch
Jacobian matrix algorithm for Lyapunov exponents of the discrete fractional maps
NASA Astrophysics Data System (ADS)
Wu, Guo-Cheng; Baleanu, Dumitru
2015-05-01
The Jacobian matrix algorithm is often used to calculate the Lyapunov exponents of the chaotic systems. This study extends the algorithm to discrete fractional cases. The tangent maps with memory effect are presented. The Lyapunov exponents of one and two dimensional fractional logistic maps are calculated. The positive ones are used to distinguish the chaotic areas of the maps.
Fully-implicit Jacobian-free Newton-Krylov Solvers for the nonhydrostatic Euler equations
NASA Astrophysics Data System (ADS)
Kelly, J. F.; Giraldo, F.; Carr, L.
2009-12-01
For most atmospheric flows, gravity and acoustic waves are the fastest waves in the system. These fast waves severely restrict the time-step in the explicit integration of the non-hydrostatic compressible Euler equations. To circumvent this problem, a fully-implicit time-integrator is proposed using the Jacobian-Free Newton Krylov (JFNK) framework. Since forming and storing the Jacobian matrix is computationally expensive, JFNK methods form the action of the Jacobian matrix on a vector. This matrix-vector computation naturally extends the semi-implicit element-based continuous Galerkin paradigm wherein a system of linear equation is solved at each time-step using a Krylov-subspace solver. The JFNK integrator is implemented for the nonhydrostatic, compressible Euler equations in non-conservative form using spectral elements and compared to pervious explicit and semi-implicit codes. Since the resulting Jacobian is poorly conditioned, a block Jacobi preconditioner is developed and implemented, resulting in a significant reduction in the number of Krylov iterations. Numerical results are reported for several test cases, including 1) a rising thermal bubble and 2) flow over hydrostatic and non-hydrostatic mountains.
Lefschetz classes of simple factors of Fermat Jacobian of prime degree over finite fields
Sugiyama, Rin
2012-01-01
We give a necessary and sufficient condition in terms of a matrix for which all Tate classes are Lefschetz for simple abelian varieties over an algebraic closure of a finite field. As an application, we prove under an assumption that all Tate classes are Lefschetz for simple factors of Fermat Jacobian of prime degree.
Motivic interpretation of Milnor K-groups attached to Jacobian varieties
Motivic interpretation of Milnor K-groups attached to Jacobian varieties Satoshi Mochizuki #3 of motives DM e#11; - (k) . Key words: motivic cohomology, 1-motives, Milnor K-groups, Weil reciprocity law Sciences, the University of Tokyo. 1 #12; 4 Motivic cohomology groups attached to pointed smooth curves 18
Magnetotelluric Inversion in a 2D Anisotropic Environment
NASA Astrophysics Data System (ADS)
Mandolesi, E.; Jones, A. G.
2012-04-01
In recent years several authors have proposed algorithms to perform magnetotelluric (MT) inversion in a 3D environment. The development of high performance computer (hpc) machines allows the solution of these inverse problems in a reasonable time, nevertheless the solution of a 3D problem remains at the present extremely challenging. Moreover it is proofed that any magnitude of anisotropy possibly present in the subsurface conductivity can be modeled by a sufficient dense discretization of a 3D isotropic domain, keeping the recognition of intrinsically anisotropic bulks virtually impossible for a 3D code. These arguments convinced us to develop a 2D inverse code able in assessing anisotropy and running in an affordable time, testing several scenario for the same dataset in the same time in which a 3D inversion code produces its first model. In this work we report results from synthetic tests we performed. MT inverse problem is challenging because of several reasons. It is both highly non-linear, ill-conditioned and suffers of a severe non-uniqueness of the solution, therefore we developed an inversion algorithm based on the classic Levenberg-Marquardt (LM) strategy, minimizing the objective function (?-G-(m)-d)2 ?(m )= ? +?aLa +?sLs in which m is the model, G the forward operator, d the data vector, L* the regularization matrix and ?* the trade-off parameter for respectively anisotropy and structure. Usually LM method is used for medium size problems, mainly because it requires the explicit computation and storage of the Jacobian matrix J and the explicit knowledge of the product JTJ. To compute the Jacobian it has proofed that the electrical reciprocity theorem is a valuable tool, allowing to compute the full Jacobian with the evaluation of one forward problem per station in spite of one forward problem per parameter as usually done with the finite-difference method. Moreover the computation of the forward response can be easily performed in parallel, due the mutual independency of the different spectral components, storing the Jacobian in a distribute machine memory and solving at the same time the problem of the huge memory requirements used to store the product JTJ and speeding up the whole process. We performed tests on the simple synthetic model released with the code from Pek and Santos [2004]: an 84-100 cells grid, grouped in 3 up to 20 blocks sharing the same conductivities. Results proof the capacity of the algorithm in recovering the subsurface structure with good precision, reaching an RMS of the magnitude 10-5 for the 20 block case without the use of regularization. More tests will be presented and results highlighted.
Rotational kinematics influence multimodal perception of heaviness.
Streit, Matthew; Shockley, Kevin; Morris, Anthony W; Riley, Michael A
2007-04-01
Perceived heaviness has been shown to be specific to an object's rotational inertia (I), its resistance to rotational acceleration. According to the kinematic specification of dynamics (KSD) principle, we hypothesized that I is optically specified by rotational kinematics. Using virtual depictions of wielded objects, we investigated whether the visually detected rotational kinematics of wielded objects would influence perceived heaviness in a manner consistent with the inertial model of heaviness perception. We scaled the virtual object's movement so that it rotated more or less than its wielded counterpart, specifying lower and higher I, respectively. Perceived heaviness was inversely related to the rotational scaling factor, consistent with a KSD interpretation of the inertial model. PMID:17694927
Ventilation from four-dimensional computed tomography: density versus Jacobian methods
NASA Astrophysics Data System (ADS)
Castillo, Richard; Castillo, Edward; Martinez, Josue; Guerrero, Thomas
2010-08-01
Two calculation methods to produce ventilation images from four-dimensional computed tomography (4DCT) acquired without added contrast have been reported. We reported a method to obtain ventilation images using deformable image registration (DIR) and the underlying CT density information. A second method performs the ventilation image calculation from the DIR result alone, using the Jacobian determinant of the deformation field to estimate the local volume changes resulting from ventilation. For each of these two approaches, there are variations on their implementation. In this study, two implementations of the Jacobian-based methodology are evaluated, as well as a single density change-based model for calculating the physiologic specific ventilation from 4DCT. In clinical practice, 99mTc-labeled aerosol single photon emission computed tomography (SPECT) is the standard method used to obtain ventilation images in patients. In this study, the distributions of ventilation obtained from the CT-based ventilation image calculation methods are compared with those obtained from the clinical standard SPECT ventilation imaging. Seven patients with 4DCT imaging and standard 99mTc-labeled aerosol SPECT/CT ventilation imaging obtained on the same day as part of a prospective validation study were selected. The results of this work demonstrate the equivalence of the Jacobian-based methodologies for quantifying the specific ventilation on a voxel scale. Additionally, we found that both Jacobian- and density-change-based methods correlate well with global measurements of the resting tidal volume. Finally, correlation with the clinical SPECT was assessed using the Dice similarity coefficient, which showed statistically higher (p-value < 10-4) correlation between density-change-based specific ventilation and the clinical reference than did either Jacobian-based implementation.
Ventilation from four-dimensional computed tomography: density versus Jacobian methods.
Castillo, Richard; Castillo, Edward; Martinez, Josue; Guerrero, Thomas
2010-08-21
Two calculation methods to produce ventilation images from four-dimensional computed tomography (4DCT) acquired without added contrast have been reported. We reported a method to obtain ventilation images using deformable image registration (DIR) and the underlying CT density information. A second method performs the ventilation image calculation from the DIR result alone, using the Jacobian determinant of the deformation field to estimate the local volume changes resulting from ventilation. For each of these two approaches, there are variations on their implementation. In this study, two implementations of the Jacobian-based methodology are evaluated, as well as a single density change-based model for calculating the physiologic specific ventilation from 4DCT. In clinical practice, (99m)Tc-labeled aerosol single photon emission computed tomography (SPECT) is the standard method used to obtain ventilation images in patients. In this study, the distributions of ventilation obtained from the CT-based ventilation image calculation methods are compared with those obtained from the clinical standard SPECT ventilation imaging. Seven patients with 4DCT imaging and standard (99m)Tc-labeled aerosol SPECT/CT ventilation imaging obtained on the same day as part of a prospective validation study were selected. The results of this work demonstrate the equivalence of the Jacobian-based methodologies for quantifying the specific ventilation on a voxel scale. Additionally, we found that both Jacobian- and density-change-based methods correlate well with global measurements of the resting tidal volume. Finally, correlation with the clinical SPECT was assessed using the Dice similarity coefficient, which showed statistically higher (p-value < 10(-4)) correlation between density-change-based specific ventilation and the clinical reference than did either Jacobian-based implementation. PMID:20671351
Kinematic Jump Processes For Monocular 3D Human Tracking
Cristian Sminchisescu; Bill Triggs
2003-01-01
A major difficulty for 3D human body tracking from monocular image sequences is the near non-observability of kinematic degrees of freedom that generate motion in depth. For known link (body seg- ment) lengths, the strict non-observabilities reduce to twofold 'for- wards\\/backwards flipping' ambiguities for each link. These imply # links formal inverse kinematics solutions for the full model, and hence
Real time markerless motion tracking using linked kinematic chains
Luck, Jason P. (Arvada, CO); Small, Daniel E. (Albuquerque, NM)
2007-08-14
A markerless method is described for tracking the motion of subjects in a three dimensional environment using a model based on linked kinematic chains. The invention is suitable for tracking robotic, animal or human subjects in real-time using a single computer with inexpensive video equipment, and does not require the use of markers or specialized clothing. A simple model of rigid linked segments is constructed of the subject and tracked using three dimensional volumetric data collected by a multiple camera video imaging system. A physics based method is then used to compute forces to align the model with subsequent volumetric data sets in real-time. The method is able to handle occlusion of segments and accommodates joint limits, velocity constraints, and collision constraints and provides for error recovery. The method further provides for elimination of singularities in Jacobian based calculations, which has been problematic in alternative methods.
Inversions for axisymmetric galactic disks
NASA Astrophysics Data System (ADS)
Hiotelis, N.; Patsis, P. A.
1993-08-01
We use two models for the distribution function to solve an inverse problem for axisymmetric disks. These systems may be considered - under certain assumptions - as galactic disks. In some cases the solutions of the resulting integral equations are simple, which allows the determination of the kinematic properties of self-consistent models for these systems. These properties for then = 1 Toomre disk are presented in this study.
NASA Astrophysics Data System (ADS)
Carr, E. J.; Turner, I. W.; Perré, P.
2013-01-01
A Jacobian-free variable-stepsize method is developed for the numerical integration of the large, stiff systems of differential equations encountered when simulating transport in heterogeneous porous media. Our method utilises the exponential Rosenbrock-Euler method, which is explicit in nature and requires a matrix-vector product involving the exponential of the Jacobian matrix at each step of the integration process. These products can be approximated using Krylov subspace methods, which permit a large integration stepsize to be utilised without having to precondition the iterations. This means that our method is truly "Jacobian-free" - the Jacobian need never be formed or factored during the simulation. We assess the performance of the new algorithm for simulating the drying of softwood. Numerical experiments conducted for both low and high temperature drying demonstrates that the new approach outperforms (in terms of accuracy and efficiency) existing simulation codes that utilise the backward Euler method via a preconditioned Newton-Krylov strategy.
NSDL National Science Digital Library
Moore, Lang
Created by Lang Moore and David Smith for the Connected Curriculum Project, this is a module to review concepts of inverse functions, and to use those concepts, together with functions defined by integrals, to develop inverse trigonometric functions. This is one within a much larger set of learning modules hosted by Duke University.
Heng-Bin An; Ju Wen; Tao Feng
2011-01-01
The Jacobian-free Newton–Krylov (JFNK) method is a special kind of Newton–Krylov algorithm, in which the matrix-vector product is approximated by a finite difference scheme. Consequently, it is not necessary to form and store the Jacobian matrix. This can greatly improve the efficiency and enlarge the application area of the Newton–Krylov method. The finite difference scheme has a strong influence on
Jean-François Lemieux; Bruno Tremblay; Jan Sedlácek; Paul Tupper; Stephen Thomas; David Huard; Jean-Pierre Auclair
2010-01-01
We have implemented the Jacobian-free Newton–Krylov (JFNK) method to solve the sea ice momentum equation with a viscous-plastic (VP) formulation. The JFNK method has many advantages: the system matrix (the Jacobian) does not need to be formed and stored, the method is parallelizable and the convergence can be nearly quadratic in the vicinity of the solution. The convergence rate of
NASA Astrophysics Data System (ADS)
Guo, L.; Huang, H.; Gaston, D.; Redden, G. D.; Permann, C.; Andrs, D.; Fox, D. T.; Fujita, Y.; Lu, C.
2011-12-01
Multicomponent reactive transport in porous media is a tightly coupled multiphysics problem often described by a system of coupled nonlinear partial differential algebraic equations (PDAEs). For reactive transport systems that are large, highly nonlinear, and tightly coupled due to complex reactions and strong solution-mineral interactions, a preconditioned Jacobian-free Newton-Krylov (JFNK) solution approach is applied to solve the PDAEs in a fully coupled, fully implicit manner. The advantage of the JFNK method is that it avoids explicit computation and storage of the Jacobian matrix during Newton nonlinear iterations, which is highly desirable for efficient solution of large reactive transport problems. This approach is also enhanced by a physics-based blocking approach for constructing the preconditioner and multigrid algorithm for efficient inversion of preconditioners. The preconditioning strategy can account for both inter-cell transport-reaction self-coupling by using the diagonal blocks of the approximate Jacobian and the additional intra-cell transport-reaction cross-coupling through off-diagonal blocks at minimal additional computational cost. Numerical results are presented to demonstrate the efficiency and massive scalability of the solution strategy for reactive transport problems involving strong solution-mineral interactions and fast kinetics. This approach has been applied to two reactive transport systems involving induced mineral precipitation. In the first system, calcite precipitation takes place as a result of the combination of injected calcium and ureolysis-produced bicarbonate ions.. In the other system, separate solutions containing calcium and bicarbonate ions are introduced into the porous medium in a parallel injection format such that calcium carbonate mineral precipitates in the mixing zone formed between the two fluids. Highly nonlinear coupling effects of fluid flow, transport, kinetic and equilibrium reactions, and changes in media properties are investigated by using the preconditioned JFNK solution approach for both systems. The numerical simulation results are compared to laboratory experiment results, and the comparison demonstrates that the fully-coupled, fully-implicit solutions can capture the transient events and sharp chemical gradients characteristic of the system, including the changes in flow properties caused by mineral precipitation and/or dissolution.
Dana Knoll; Chris Newman
2011-01-01
We present a new approach for the $k$--eigenvalue problem using a combination of classical power iteration and the Jacobian--free Newton--Krylov method (JFNK). The method poses the $k$--eigenvalue problem as a fully coupled nonlinear system, which is solved by JFNK with an effective block preconditioning consisting of the power iteration and algebraic multigrid. We demonstrate effectiveness and algorithmic scalability of the
G. E. Hammond; A. J. Valocchi; P. C. Lichtner
2005-01-01
Modern multicomponent geochemical transport models require the use of parallel computation for carrying out three-dimensional, field-scale simulations due to extreme memory and processing demands. However, to fully exploit the advanced computational power provided by today's supercomputers, innovative parallel algorithms are needed. We demonstrate the use of Jacobian-free Newton Krylov (JFNK) within the Newton Raphson method to reduce memory and processing
G. E. Hammond; A. J. Valocchi; P. C. Lichtner
2005-01-01
Modern multicomponent geochemical transport models require the use of parallel computation for carrying out three-dimensional, field-scale simulations due to extreme memory and processing demands. However, to fully exploit the advanced computational power provided by today’s supercomputers, innovative parallel algorithms are needed. We demonstrate the use of Jacobian-free Newton–Krylov (JFNK) within the Newton–Raphson method to reduce memory and processing requirements on
A Jacobian-free Newton–Krylov algorithm for compressible turbulent fluid flows
Todd T. Chisholm; David W. Zingg
2009-01-01
Despite becoming increasingly popular in many branches of computational physics, Jacobian-free Newton–Krylov (JFNK) methods have not become the approach of choice in the solution of the compressible Navier–Stokes equations for turbulent aerodynamic flows. To a degree, this is related to some subtle aspects of JFNK methods that are not well understood, and, if poorly handled, can lead to inefficient and
NASA Astrophysics Data System (ADS)
Fiorino, Claudio; Maggiulli, Eleonora; Broggi, Sara; Liberini, Simone; Mauro Cattaneo, Giovanni; Dell'Oca, Italo; Faggiano, Elena; Di Muzio, Nadia; Calandrino, Riccardo; Rizzo, Giovanna
2011-06-01
The Jacobian of the deformation field of elastic registration between images taken during radiotherapy is a measure of inter-fraction local deformation. The histogram of the Jacobian values (Jac) within an organ was introduced (JVH—Jacobian-volume-histogram) and first applied in quantifying parotid shrinkage. MVCTs of 32 patients previously treated with helical tomotherapy for head-neck cancers were collected. Parotid deformation was evaluated through elastic registration between MVCTs taken at the first and last fractions. Jac was calculated for each voxel of all parotids, and integral JVHs were calculated for each parotid; the correlation between the JVH and the planning dose-volume histogram (DVH) was investigated. On average, 82% (±17%) of the voxels shrinks (Jac < 1) and 14% (±17%) shows a local compression >50% (Jac < 0.5). The best correlation between the DVH and the JVH was found between V10 and V15, and Jac < 0.4-0.6 (p < 0.01). The best constraint predicting a higher number of largely compressing voxels (Jac0.5<7.5%, median value) was V15 >= 75% (OR: 7.6, p = 0.002). Jac and the JVH are promising tools for scoring/modelling toxicity and for evaluating organ/contour variations with potential applications in adaptive radiotherapy.
Multiscale modeling of polycrystalline materials with Jacobian-free multiscale method (JFMM)
NASA Astrophysics Data System (ADS)
Rahul; De, Suvranu
2015-04-01
The non-linear constitutive response of polycrystalline aggregate of single crystal grains is obtained using a micro-macro transition scheme, which is realized within a Jacobian-free multiscale method (JFMM). The Jacobian-free approach circumvents computation of the tangent matrix at the macroscale using a Newton-Krylov process. This has a major advantage in terms of storage requirements and computational cost over existing approaches based on homogenized material coefficients, which may require considerable effort to form the exact Jacobian at every Newton step. The rate-independent constitutive response of polycrystalline copper and rate-dependent stress-strain response of -RDX (cyclotrimethylene trinitramine) polycrystal is verified against the computational homogenization based two-level finite element multiscale method. Numerical examples demonstrate that while the rate of convergence of Newton iterations for the JFMM and method is comparable, the computational cost of JFMM is nearly constant as opposed to exponential increase for the latter with increasing number of degrees of freedom at the macroscale. The storage requirement for the JFMM increases linearly with increasing , whereas, it increases as approximately for the method.
New 3D parallel SGILD modeling and inversion
Xie, G.; Li, J.; Majer, E.
1998-09-01
In this paper, a new parallel modeling and inversion algorithm using a Stochastic Global Integral and Local Differential equation (SGILD) is presented. The authors derived new acoustic integral equations and differential equation for statistical moments of the parameters and field. The new statistical moments integral equation on the boundary and local differential equations in domain will be used together to obtain mean wave field and its moments in the modeling. The new moments global Jacobian volume integral equation and the local Jacobian differential equations in domain will be used together to update the mean parameters and their moments in the inversion. A new parallel multiple hierarchy substructure direct algorithm or direct-iteration hybrid algorithm will be used to solve the sparse matrices and one smaller full matrix from domain to the boundary, in parallel. The SGILD modeling and imaging algorithm has many advantages over the conventional imaging approaches. The SGILD algorithm can be used for the stochastic acoustic, electromagnetic, and flow modeling and inversion, and are important for the prediction of oil, gas, coal, and geothermal energy reservoirs in geophysical exploration.
... lesions in the skin folds. People with severe inverse psoriasis may occasionally require UVB (ultraviolet B) light therapy or biologic medications to control the condition. Psoriasis About Psoriasis Symptoms and Diagnosis ...
MODULAR AND RECURSIVE KINEMATICS AND DYNAMICS FOR PARALLEL MANIPULATORS
Krovi, Venkat
MODULAR AND RECURSIVE KINEMATICS AND DYNAMICS FOR PARALLEL MANIPULATORS Waseem Ahmad Khan (wakhan. The presence of these passive joints interferes with the effective modular formulation of the dynamic equations forward and inverse dynamics applications. Thus, in this paper, we examine the development of modular
Kinematic synthesis of bevel-gear-type robotic wrist mechanisms
NASA Astrophysics Data System (ADS)
Lin, Chen-Chou
Bevel-gear-type robotic wrist mechanisms are commonly used in industry. The reasons for their popularity are that they are compact, light-weight, and relatively inexpensive. However, there are singularities in their workspace, which substantially degrade their manipulative performance. The objective of this research is to develop an atlas of three-degree-of-freedom bevel-gear-type wrist mechanisms, and through dimensional synthesis to improve their kinematic performance. The dissertation contains two major parts: the first is structural analysis and synthesis, the other is kinematic analysis and dimensional synthesis. To synthesize the kinematic structures of bevel-gear-type wrist mechanisms, the kinematic structures are separated from their functional considerations. All kinematic structures which satisfy the mobility condition are enumerated in an unbiased, systematic manner. Then the bevel-gear-type wrist mechanisms are identified by applying the functional requirements. Structural analysis shows that a three-degree-of-freedom wrist mechanism usually consists of non-fractionated, two degree-of-freedom epicyclic gear train jointed with the base link. Therefore, the structural synthesis can be simplified into a problem of examining the atlas of non-fractionated, two-degree-of-freedom epicyclic gear trains. The resulting bevel-gear-type wrist mechanism has been categorized and evaluated. It is shown that three-degree-of-freedom, four-jointed wrist mechanisms are promising for further improving the kinematic performance. It is found that a spherical planetary gear train is necessarily imbedded in a three-degree-of-freedom, four-jointed wrist mechanism. Therefore, to study the workspace and singularity problems of three-degree-of-freedom four-jointed spherical wrist mechanisms, we have to study the trajectories of spherical planetary gear trains. The parametric equations of the trajectories and some useful geometric properties for the analysis and synthesis of workplace are derived. The workspace boundary equations can be derived via both geometric consideration and Jacobian analysis. The workspace is divided by inner and outer boundaries into regions of accessibility of zero, two, and four. The design criteria of full workspace and a maximum four-root region are established.
Estimation of parameter uncertainty using inverse model sensitivites
Vesselinov, V. V.
2004-01-01
Forward model sensitivities are commonly applied to evaluate the uncertainty in model parameter estimates obtained through inverse analysis. In this case, the forward sensitivity (Jacobian) matrix is applied to compute an approximate representation of the covariance matrix of inverse parameter estimates. However, this approach can produce biased estimates of the covariance matrix because it does not account accurately for correlations between uncertainty of calibration targets and estimates. Typically, these correlations are non-linear and depend on the spatial and temporal structure of inverse targets and estimated parameters. A better but much more computationally intensive method, which we call inverse-sensitivity approach, directly evaluates the sensitivity of inverse estimates of model parameters with respect to the calibration targets. Further, we can also evaduate the sensitivity of model prediction based on inverse model parameter estimates with respect to the calibration targets. The proposed methodology can be applied to problems such as estimation of predictive uncertainty, optimization of data collection strategies, and design of monitoring networks. Its implementation can be performed efficiently through parallelization. Results based on a simple groundwater flow inverse problem are presented to illustrate the basis for the method.
NASA Astrophysics Data System (ADS)
Druskin, Vladimir; Zaslavsky, Mikhail
2007-08-01
We suggest an approach to speed up the Gauss-Newton solution of inverse partial differential equation problems by minimizing the number of forward problem calls. The acceleration is based on effective incorporation of the information from the previous iterations via a reduced-order model (ROM). It is designed with the help of Galerkin and pseudo-Galerkin methods for self-adjoint and complex symmetric problems respectively. The constructed ROM generates effective multivariate rational interpolation matching the forward solutions and the Jacobians from the previous iterations. Numerical examples for the inverse conductivity problem for the 3D Maxwell system show significant accelerations.
Kinematic block model of Switzerland
NASA Astrophysics Data System (ADS)
Villiger, Arturo; Geiger, Alain; Brockmann, Elmar
2010-05-01
In 1997 swisstopo began to install and operate the Automated GPS Network for Switzerland (AGNES). Since then the network has been extended to more than 30 stations. From the time series swisstopo derives velocities which are used to create kinematic models of Switzerland under the assumption that the velocities correspond to the tectonic motion. However, one has to be aware of the very small crustal movements relative to the Eurasian plate. The expected velocities are in the range of 1 to 2 millimetres per year. Local influences like monumentation instability and landslides are not negligible and can bias the velocities significantly. For this purpose the time series were initially analysed for common mode effects and seasonal movements using stacking methods. Additional information from the Tectonic Map of Switzerland, published by swisstopo, helps to delimitate regions belonging to the same with kinematic pattern. The area covering the whole country has been separated into several blocks namely Jura, Basin, Prealps, and Alps. The movements of the blocks were determined by robust estimation, thus reducing the influence of velocities biased by local effects. During this process several stations had to be eliminated by reducing their weight in the inversion. The individual blocks were modelled by the assumption of rigid body dynamics. Two translations and one rotation about the Z-axis have been introduced for the horizontal movements. The vertical velocities are analysed separately using the same block assignments. The unknowns for each vertical block movement are one translation and two rotations about the X- and Y-axis. The block model gives a good first approximation of the tectonic deformation in Switzerlan
Inverse obstacle transmission problem in acoustics
NASA Astrophysics Data System (ADS)
Ghosh Roy, D. N.; Warner, J.; Couchman, L. S.; Shirron, J.
1998-08-01
The results of inverse scattering of plane acoustic waves from penetrable, homogeneous acoustic obstacles in two space dimensions are reported. The shape and the material parameters of the obstacles are recovered from both 0266-5611/14/4/010/img7 and limited-aperture, far-field patterns in the presence of random noise. The forward problem is solved via a combination of shape differentiation of the scattered field and the Padé approximation. Not being an integral equation based approach, the method is free of the non-uniqueness problem associated with the interior eigenvalues of the scatterer. Moreover, it is shown that all necessary scattering and Jacobian calculations need to be performed only with respect to a circle of a fixed radius. In addition, by the construction of the forward solution, the objective function to be minimized for inversion does not contain terms arising from the boundary conditions. This, along with the fact that the domain of calculations remains invariant to the stage of iteration, results in a substantial simplification in the implementation of a Gauss-Newton type of inversion procedure which is used here. Finally, the method is illustrated with several transmission obstacles of various shapes and with different initial conditions.
Pavel Yu. Moshin; Alexander A. Reshetnyak
2015-06-23
We continue our research arXiv:1405.0790[hep-th], arXiv:1405.7549[hep-th], arXiv:1406.0179[hep-th], arXiv:1406.5086[hep-th] and extend the class of finite BRST-antiBRST transformations with odd-valued parameters $\\lambda_{a}$, $a=1,2$, introduced in these works. In doing so, we calculate the Jacobians induced by linearized finite BRST-antiBRST transformations with functionally-dependent parameters, as well as those induced by finite BRST-antiBRST transformations with arbitrary functional parameters. The calculations cover the cases of gauge theories with a closed algebra, dynamical systems with first-class constraints, and general gauge theories. The resulting Jacobians in the case of linearized transformations are different from those in the case of polynomial dependence on the parameters. Finite BRST-antiBRST transformations with arbitrary parameters induce an extra contribution to the quantum action, which cannot be absorbed into a change of the gauge. These transformations include an extended case of functionally-dependent parameters that implies a modified compensation equation, which, in particular, admits non-trivial solutions leading to a Jacobian equal to unity. Finite BRST-antiBRST transformations with functionally-dependent parameters are applied to the Standard Model, and an explicit form of functionally-dependent parameters $\\lambda_{a}$ is obtained, providing the equivalence of path integrals in any $3$-parameter $R_{\\boldsymbol{\\xi}}$-like gauges. The Gribov--Zwanziger theory is extended to the case of the Standard Model, and a form of the Gribov horizon functional is suggested in the Landau gauge, as well as in $R_{\\boldsymbol{\\xi}}$-like gauges, in a gauge-independent way using field-dependent BRST-antiBRST transformations, and in $R_{\\boldsymbol{\\xi}}$-like gauges using transverse-like non-Abelian gauge fields.
Kinematic control of robot with degenerate wrist
NASA Technical Reports Server (NTRS)
Barker, L. K.; Moore, M. C.
1984-01-01
Kinematic resolved rate equations allow an operator with visual feedback to dynamically control a robot hand. When the robot wrist is degenerate, the computed joint angle rates exceed operational limits, and unwanted hand movements can result. The generalized matrix inverse solution can also produce unwanted responses. A method is introduced to control the robot hand in the region of the degenerate robot wrist. The method uses a coordinated movement of the first and third joints of the robot wrist to locate the second wrist joint axis for movement of the robot hand in the commanded direction. The method does not entail infinite joint angle rates.
Recovery Discontinuous Galerkin Jacobian-Free Newton-Krylov Method for All-Speed Flows
Robert Nourgaliev; Vincent Mousseau; Dana Knoll
2008-01-01
A novel numerical algorithm (rDG-JFNK) for all-speed fluid flows with heat conduction and viscosity is introduced. The rDG-JFNK combines the Discontinuous Galerkin spatial discretization with the implicit Runge-Kutta time integration under the Jacobian-free Newton-Krylov framework. We solve fully-compressible Navier-Stokes equations without operator-splitting of hyperbolic, diffusion and reaction terms, which enables fully-coupled high-order temporal discretization. The stability constraint is removed due
Acceleration of k-Eigenvalue / Criticality Calculations using the Jacobian-Free Newton-Krylov Method
Dana Knoll; HyeongKae Park; Chris Newman
2011-02-01
We present a new approach for the $k$--eigenvalue problem using a combination of classical power iteration and the Jacobian--free Newton--Krylov method (JFNK). The method poses the $k$--eigenvalue problem as a fully coupled nonlinear system, which is solved by JFNK with an effective block preconditioning consisting of the power iteration and algebraic multigrid. We demonstrate effectiveness and algorithmic scalability of the method on a 1-D, one group problem and two 2-D two group problems and provide comparison to other efforts using silmilar algorithmic approaches.
Assessing the quality of curvilinear coordinate meshes by decomposing the Jacobian matrix
NASA Technical Reports Server (NTRS)
Kerlick, G. D.; Klopfer, G. H.
1982-01-01
An algebraic decomposition of the Jacobian matrix which relates physical and computational variables is presented. This invertible decomposition parameterizes the mesh by the physically intuitive qualities of cell orientation, cell orthogonality, cell volume, and cell aspect ratio. The decomposition can be used to analyze numerically generated curvilinear coordinate meshes and to assess the contribution of the mesh to the truncation error for any specific differential operator and algorithm. This is worked out in detail for Laplace's equation in nonconservative and conservative forms. The analysis is applied to the solution of the full potential code TAIR, showing grid plots, carpet plots, and truncation error for a NACA 0012 airfoil.
Andersen, David R. [NRC Herzberg Institute of Astrophysics, 5071 W Saanich Road, Victoria, BC V9E 2E7 (Canada); Bershady, Matthew A., E-mail: david.andersen@nrc-cnrc.gc.ca, E-mail: mab@astro.wisc.edu [Department of Astronomy, University of Wisconsin, 475 N Charter Street, Madison, WI 53706 (United States)
2013-05-01
Using the integral field unit DensePak on the WIYN 3.5 m telescope we have obtained H{alpha} velocity fields of 39 nearly face-on disks at echelle resolutions. High-quality, uniform kinematic data and a new modeling technique enabled us to derive accurate and precise kinematic inclinations with mean i{sub kin} = 23 Degree-Sign for 90% of these galaxies. Modeling the kinematic data as single, inclined disks in circular rotation improves upon the traditional tilted-ring method. We measure kinematic inclinations with a precision in sin i of 25% at 20 Degree-Sign and 6% at 30 Degree-Sign . Kinematic inclinations are consistent with photometric and inverse Tully-Fisher inclinations when the sample is culled of galaxies with kinematic asymmetries, for which we give two specific prescriptions. Kinematic inclinations can therefore be used in statistical ''face-on'' Tully-Fisher studies. A weighted combination of multiple, independent inclination measurements yield the most precise and accurate inclination. Combining inverse Tully-Fisher inclinations with kinematic inclinations yields joint probability inclinations with a precision in sin i of 10% at 15 Degree-Sign and 5% at 30 Degree-Sign . This level of precision makes accurate mass decompositions of galaxies possible even at low inclination. We find scaling relations between rotation speed and disk-scale length identical to results from more inclined samples. We also observe the trend of more steeply rising rotation curves with increased rotation speed and light concentration. This trend appears to be uncorrelated with disk surface brightness.
Three tooth kinematic coupling
Hale, Layton C. (Livermore, CA)
2000-01-01
A three tooth kinematic coupling based on having three theoretical line contacts formed by mating teeth rather than six theoretical point contacts. The geometry requires one coupling half to have curved teeth and the other coupling half to have flat teeth. Each coupling half has a relieved center portion which does not effect the kinematics, but in the limit as the face width approaches zero, three line contacts become six point contacts. As a result of having line contact, a three tooth coupling has greater load capacity and stiffness. The kinematic coupling has application for use in precision fixturing for tools or workpieces, and as a registration device for a work or tool changer or for optics in various products.
Three tooth kinematic coupling
Hale, L.C.
2000-05-23
A three tooth kinematic coupling is disclosed based on having three theoretical line contacts formed by mating teeth rather than six theoretical point contacts. The geometry requires one coupling half to have curved teeth and the other coupling half to have flat teeth. Each coupling half has a relieved center portion which does not effect the kinematics, but in the limit as the face width approaches zero, three line contacts become six point contacts. As a result of having line contact, a three tooth coupling has greater load capacity and stiffness. The kinematic coupling has application for use in precision fixturing for tools or workpieces, and as a registration device for a work or tool changer or for optics in various products.
Kinematics: Speed, Velocity & Acceleration
NSDL National Science Digital Library
2010-01-01
The following resource is a NFL sponsored, National Science Foundation funded program intended to teach students about scientific concepts by using the popular sport of Football. Each lesson is accompanied by an informative and fast paced video. In this lesson, students will explore kinematics on the playing field. NSF-funded scientists Tony Schmitz from the University of Florida and John Ziegert of Clemson University explain how the kinematic concepts of position, velocity and acceleration can be used to define how a running back moves.
NSDL National Science Digital Library
This set of questions, presented by the University of Oregon, asks visitors to solve mechanical physics problems related to one-dimensional kinematics. The problems are divided into two sections: questions about velocity ("Two trains on a bridge"), and questions about acceleration ("A Dog Chasing a Jogger"). Each question allows students to get a hint in solving the problem, and solutions are linked to each question. This resource would be helpful for students to study for physics exams, or for educators to use as review of physics materials in kinematics.
Holland, David
A comparison of the Jacobian-free NewtonKrylov method and the EVP model for solving the sea ice developed Jacobian-free NewtonKrylov (JFNK) solver are compared to the ones of the widely used EVP model 2012 Available online 26 May 2012 Keywords: Sea ice Viscous-plastic rheology NewtonKrylov method
Evaluation of the Jacobians of Infrared Radiation Models for Variational Data Assimilation.
NASA Astrophysics Data System (ADS)
Chevallier, Frédéric; Mahfouf, Jean-François
2001-08-01
In this paper, linearized versions of fast infrared radiative transfer schemes for variational data assimilation are studied. A neural network-based infrared broadband radiation model (NeuroFlux) is compared with the European Centre for Medium-Range Weather Forecasts operational radiation model. Also, the Radiative Transfer for Television and Infrared Observation Satellite Operational Vertical Sounder (RTTOV) scheme for satellite brightness temperature computation is compared with a more physically based scheme: the narrowband Synsatrad model developed at the European Organization for the Exploitation of Meteorological Satellites. The Jacobians are examined. They are converted into flux perturbations with the tangent-linear approximation and into atmospheric variable increments with a one-dimensional variational assimilation system. For NeuroFlux and RTTOV, despite accurate flux and radiance computation, the sensitivity with respect to water vapor needs to be improved. However, the random structure of the neural network derivative error allows the use of NeuroFlux with a single mean Jacobian in the variational context. Also, further improvements to RTTOV are expected from ongoing work on the regression dataset and on the choice of the regression predictors.
Jacobian-free Newton-Krylov methods with GPU acceleration for computing nonlinear ship wave patterns
NASA Astrophysics Data System (ADS)
Pethiyagoda, Ravindra; McCue, Scott W.; Moroney, Timothy J.; Back, Julian M.
2014-07-01
The nonlinear problem of steady free-surface flow past a submerged source is considered as a case study for three-dimensional ship wave problems. Of particular interest is the distinctive wedge-shaped wave pattern that forms on the surface of the fluid. By reformulating the governing equations with a standard boundary-integral method, we derive a system of nonlinear algebraic equations that enforce a singular integro-differential equation at each midpoint on a two-dimensional mesh. Our contribution is to solve the system of equations with a Jacobian-free Newton-Krylov method together with a banded preconditioner that is carefully constructed with entries taken from the Jacobian of the linearised problem. Further, we are able to utilise graphics processing unit acceleration to significantly increase the grid refinement and decrease the run-time of our solutions in comparison to schemes that are presently employed in the literature. Our approach provides opportunities to explore the nonlinear features of three-dimensional ship wave patterns, such as the shape of steep waves close to their limiting configuration, in a manner that has been possible in the two-dimensional analogue for some time.
Fast unsteady flow computations with a Jacobian-free Newton-Krylov algorithm
NASA Astrophysics Data System (ADS)
Lucas, Peter; van Zuijlen, Alexander H.; Bijl, Hester
2010-12-01
Despite the advances in computer power and numerical algorithms over the last decades, solutions to unsteady flow problems remain computing time intensive. Especially for large Reynolds number flows, nonlinear multigrid, which is commonly used to solve the nonlinear systems of equations, converges slowly. The stiffness induced by the large aspect ratio cells and turbulence is not tackled well by this solution method. In previous work we showed that a Jacobian-free Newton-Krylov ( JFNK) algorithm, preconditioned with an approximate factorization of the Jacobian that approximately matches the target residual operator, enables a speed up of a factor of 10 compared to standard nonlinear multigrid for two-dimensional, large Reynolds number, unsteady flow computations. The goal of this paper is to demonstrate that the JFNK algorithm is also suited to tackle the stiffness induced by the maximum aspect ratio, the grid density, the physical time step and the Reynolds number. Compared to standard nonlinear multigrid, speed ups up to a factor of 25 are achieved.
Jacobian-free Newton-Krylov methods with GPU acceleration for computing nonlinear ship wave patterns
Pethiyagoda, Ravindra; Moroney, Timothy J; Back, Julian M
2014-01-01
The nonlinear problem of steady free-surface flow past a submerged source is considered as a case study for three-dimensional ship wave problems. Of particular interest is the distinctive wedge-shaped wave pattern that forms on the surface of the fluid. By reformulating the governing equations with a standard boundary-integral method, we derive a system of nonlinear algebraic equations that enforce a singular integro-differential equation at each midpoint on a two-dimensional mesh. Our contribution is to solve the system of equations with a Jacobian-free Newton-Krylov method together with a banded preconditioner that is carefully constructed with entries taken from the Jacobian of the linearised problem. Further, we are able to utilise graphics processing unit acceleration to significantly increase the grid refinement and decrease the run-time of our solutions in comparison to schemes that are presently employed in the literature. Our approach provides opportunities to explore the nonlinear features of three-...
Recovery Discontinuous Galerkin Jacobian-Free Newton-Krylov Method for All-Speed Flows
HyeongKae Park; Robert Nourgaliev; Vincent Mousseau; Dana Knoll
2008-07-01
A novel numerical algorithm (rDG-JFNK) for all-speed fluid flows with heat conduction and viscosity is introduced. The rDG-JFNK combines the Discontinuous Galerkin spatial discretization with the implicit Runge-Kutta time integration under the Jacobian-free Newton-Krylov framework. We solve fully-compressible Navier-Stokes equations without operator-splitting of hyperbolic, diffusion and reaction terms, which enables fully-coupled high-order temporal discretization. The stability constraint is removed due to the L-stable Explicit, Singly Diagonal Implicit Runge-Kutta (ESDIRK) scheme. The governing equations are solved in the conservative form, which allows one to accurately compute shock dynamics, as well as low-speed flows. For spatial discretization, we develop a “recovery” family of DG, exhibiting nearly-spectral accuracy. To precondition the Krylov-based linear solver (GMRES), we developed an “Operator-Split”-(OS) Physics Based Preconditioner (PBP), in which we transform/simplify the fully-coupled system to a sequence of segregated scalar problems, each can be solved efficiently with Multigrid method. Each scalar problem is designed to target/cluster eigenvalues of the Jacobian matrix associated with a specific physics.
ERIC Educational Resources Information Center
Nelson, Jane Bray; Nelson, Jim
2009-01-01
Written by Jim and Jane Nelson, Teaching About Kinematics is the latest AAPT/PTRA resource book. Based on physics education research, the book provides teachers with the resources needed to introduce students to some of the fundamental building blocks of physics. It is a carefully thought-out, step-by-step laboratory-based introduction to the…
Geometries for Possible Kinematics
Chao-Guang Huang; Yu Tian; Xiao-Ning Wu; Zhan Xu; Bin Zhou
2010-07-21
The algebras for all possible Lorentzian and Euclidean kinematics with $\\frak{so}(3)$ isotropy except static ones are re-classified. The geometries for algebras are presented by contraction approach. The relations among the geometries are revealed. Almost all geometries fall into pairs. There exists $t \\leftrightarrow 1/(\
Parallelizing Explicit Formula for Arithmetic in the Jacobian of Hyperelliptic Curves
International Association for Cryptologic Research (IACR)
- metic in genus 2 hyperelliptic curve { both for the aÆne coordinate and inversion free arithmetic of explicit formula. For the case of inversion free arith- metic, we present parallel algorithms using 4, 8
Kinematic Motor Learning Wolfram Schenck
Moeller, Ralf
Kinematic Motor Learning Wolfram Schenck Computer Engineering Group Faculty of Technology Bielefeld-521-106-6440 mail: wschenck@ti.uni-bielefeld.de Abstract This paper focuses on adaptive motor control in the kinematic domain. Several motor learning strategies from the literature are adopted to kinematic problems
PHYSICS 115 DESIGN PRACTICAL: KINEMATICS
Gustafsson, Torgny
PHYSICS 115 DESIGN PRACTICAL: KINEMATICS The goal of this experiment is to determine whether of motion. This is an activity in which you will apply the kinematic equations derived in class to two kinematics equations to predict where the two cars will meet if they start a certain distance apart
Modeling and control of a PowerSail
Naik, Kishore Shivdas
2002-01-01
and Incidence matrices . . . . 11. 2. 1. 4 Inverse Kinematics. 11. 2. 1. 5 Higher order kinematics and the Jacobian . . . II. 2. 2 Dynamics. II. 2. 2. 1 Newton-Euler equations of motion for multi-body systems . II. 2. 2. 2 Lagrangian Formulation. II. 2. 2... . . . . 29 III. 1. 3 Inverse Kinematics of PS (velocity level) . . . . III. 2 Simulations and Results (Inverse Kinematics) . . . IV Dynanncs of the PS System. IV. I Newton-Euler Formulation and the Closed form of . . . . 30 . . . . 36...
AN INVERSE KINEMATIC MATHEMATICAL MODEL USING GROEBNER BASIS THEORY FOR
and orientation of a jointed flexible object in space, and the IK- problem is the process of determining all combinations of a jointed flexible object in order to achieve a desired position and orientation in space capability, efficiency, and accuracy for various robot manipulators. It's been proven that Groebner Basis
Kinematic and Dynamic Inversion of the 2008 Northern Iwate Earthquake
Madariaga, Raúl
, and large stress drops in the 3045 MPa range. Rupture duration was less than 3 s because of very high sub-Rayleigh of solutions that fit the strong-motion data within a certain error, confirming the strong trade-off among dynamically similar models fit the observations with approximately the same misfit. Online Material: Figures
Mesh Puppetry: Cascading Optimization of Mesh Deformation with Inverse Kinematics
Zhou, Kun
,mathieu}@caltech.edu Figure 1: Armadillo Olympics: The Armadillo model (top left) can be deformed to take various sport poses of its hands and feet is enough to make the Armadillo look like it is bouncing off a springboard (high
Mesh Puppetry: Cascading Optimization of Mesh Deformation with Inverse Kinematics
Desbrun, Mathieu
-mail:{kunzhou,bainguo}@microsoft.com e-mail: {yiying,mathieu}@caltech.edu Figure 1: Armadillo Olympics: The Armadillo model (top left the Armadillo look like it is bouncing off a springboard (high diving, top right); or the pose of a sprint
EFFICIENT INVERSE KINEMATICS ALGORITHM BASED ON CONFORMAL GEOMETRIC ALGEBRA
entity standard repr. direct repr. Point P = x+ 1 2 x2e +e0 Sphere s = P- 1 2 r2e s = x1 x2 x3 x4 Plane = n+de = x1 x2 x3 e Circle z = s1 s2 z = x1 x2 x3 Line l = 1 1 l = x1 x2 e Point Pair Pp = s1 s2 s3 P
Wilamowski, Bogdan Maciej
Vector and Jacobian Matrix in Arbitrarily Connected Neural Networks Bogdan M. Wilamowski, Fellow, IEEE networks. Index Terms--Learning, neural network. I. INTRODUCTION RECENTLY, we have observed an increased interest in applications of neural networks in industrial electronics. In the February 2007 "Special
Quantum deformed magnon kinematics
Cesar Gomez; Rafael Hernandez
2007-03-23
The dispersion relation for planar N=4 supersymmetric Yang-Mills is identified with the Casimir of a quantum deformed two-dimensional kinematical symmetry, E_q(1,1). The quantum deformed symmetry algebra is generated by the momentum, energy and boost, with deformation parameter q=e^{2\\pi i/\\lambda}. Representing the boost as the infinitesimal generator for translations on the rapidity space leads to an elliptic uniformization with crossing transformations implemented through translations by the elliptic half-periods. This quantum deformed algebra can be interpreted as the kinematical symmetry of a discrete integrable model with lattice spacing given by the BMN length a=2\\pi/\\sqrt{\\lambda}. The interpretation of the boost generator as the corner transfer matrix is briefly discussed.
NASA Astrophysics Data System (ADS)
Nuber, André; Manukyan, Edgar; Maurer, Hansruedi
2014-05-01
Conventional methods of interpreting seismic data rely on filtering and processing limited portions of the recorded wavefield. Typically, either reflections, refractions or surface waves are considered in isolation. Particularly in near-surface engineering and environmental investigations (depths less than, say 100 m), these wave types often overlap in time and are difficult to separate. Full waveform inversion is a technique that seeks to exploit and interpret the full information content of the seismic records without the need for separating events first; it yields models of the subsurface at sub-wavelength resolution. We use a finite element modelling code to solve the 2D elastic isotropic wave equation in the frequency domain. This code is part of a Gauss-Newton inversion scheme which we employ to invert for the P- and S-wave velocities as well as for density in the subsurface. For shallow surface data the use of an elastic forward solver is essential because surface waves often dominate the seismograms. This leads to high sensitivities (partial derivatives contained in the Jacobian matrix of the Gauss-Newton inversion scheme) and thus large model updates close to the surface. Reflections from deeper structures may also include useful information, but the large sensitivities of the surface waves often preclude this information from being fully exploited. We have developed two methods that balance the sensitivity distributions and thus may help resolve the deeper structures. The first method includes equilibrating the columns of the Jacobian matrix prior to every inversion step by multiplying them with individual scaling factors. This is expected to also balance the model updates throughout the entire subsurface model. It can be shown that this procedure is mathematically equivalent to balancing the regularization weights of the individual model parameters. A proper choice of the scaling factors required to balance the Jacobian matrix is critical. We decided to normalise the columns of the Jacobian based on their absolute column sum, but defining an upper threshold for the scaling factors. This avoids particularly small and therefore insignificant sensitivities being over-boosted, which would produce unstable results. The second method proposed includes adjusting the inversion cell size with depth. Multiple cells of the forward modelling grid are merged to form larger inversion cells (typical ratios between forward and inversion cells are in the order of 1:100). The irregular inversion grid is adapted to the expected resolution power of full waveform inversion. Besides stabilizing the inversion, this approach also reduces the number of model parameters to be recovered. Consequently, the computational costs and the memory consumption are reduced significantly. This is particularly critical when Gauss-Newton type inversion schemes are employed. Extensive tests with synthetic data demonstrated that both methods stabilise the inversion and improve the inversion results. The two methods have some redundancy, which can be seen when both are applied simultaneously, that is, when scaling of the Jacobian matrix is applied to an irregular inversion grid. The calculated scaling factors are quite balanced and span a much smaller range than in the case of a regular inversion grid.
Huang, C Q; Xie, L F; Liu, Y L
2012-11-01
In framework of traditional PID controllers, there are only three parameters available to tune, as a result, performance of the resulting system is always limited. As for Cartesian regulation of robot manipulators with uncertain Jacobian matrix, a scheme of PID controllers with error-dependent integral action is proposed. Compare with traditional PID controllers, the error-dependent integration is employed in the proposed PID controller, in which more parameters are available to be tuned. It provides additional flexibility for controller characteristics and tuning as well, and hence makes better transient performance. In addition, asymptotic stability of the resulting closed-loop system is guaranteed. All signals in the system are bounded when exogenous disturbances and measurement noises are bounded. Numerical example demonstrates the superior transient performance of the proposed controller over the traditional one via Cartesian space set-point manipulation of two-link robotic manipulator. PMID:22818429
NASA Astrophysics Data System (ADS)
Reynolds, Daniel R.; Samtaney, Ravi; Tiedeman, Hilari C.
2012-01-01
Single-fluid resistive magnetohydrodynamics (MHD) is a fluid description of fusion plasmas which is often used to investigate macroscopic instabilities in tokamaks. In MHD modeling of tokamaks, it is often desirable to compute MHD phenomena to resistive time scales or a combination of resistive-Alfvén time scales, which can render explicit time stepping schemes computationally expensive. We present recent advancements in the development of preconditioners for fully nonlinearly implicit simulations of single-fluid resistive tokamak MHD. Our work focuses on simulations using a structured mesh mapped into a toroidal geometry with a shaped poloidal cross-section, and a finite-volume spatial discretization of the partial differential equation model. We discretize the temporal dimension using a fully implicit ? or the backwards differentiation formula method, and solve the resulting nonlinear algebraic system using a standard inexact Newton-Krylov approach, provided by the sundials library. The focus of this paper is on the construction and performance of various preconditioning approaches for accelerating the convergence of the iterative solver algorithms. Effective preconditioners require information about the Jacobian entries; however, analytical formulae for these Jacobian entries may be prohibitive to derive/implement without error. We therefore compute these entries using automatic differentiation with OpenAD. We then investigate a variety of preconditioning formulations inspired by standard solution approaches in modern MHD codes, in order to investigate their utility in a preconditioning context. We first describe the code modifications necessary for the use of the OpenAD tool and sundials solver library. We conclude with numerical results for each of our preconditioning approaches in the context of pellet-injection fueling of tokamak plasmas. Of these, our optimal approach results in a speedup of a factor of 3 compared with non-preconditioned implicit tests, with that performance gap rapidly widening with increasing mesh refinement.
Radiance and Jacobian Intercomparison of Radiative Transfer Models Applied to HIRS and AMSU Channels
NASA Technical Reports Server (NTRS)
Garand, L.; Turner, D. S.; Larocque, M.; Bates, J.; Boukabara, S.; Brunel, P.; Chevallier, F.; Deblonde, G.; Engelen, R.; Hollingshead, M.; Goodman, H. Michael (Technical Monitor)
2000-01-01
The goals of this study are the evaluation of current fast radiative transfer models (RTMs) and line-by-line (LBL) models. The intercomparison focuses on the modeling of 11 representative sounding channels routinely used at numerical weather prediction centers: 7 HIRS (High-resolution Infrared Sounder) and 4 AMSU (Advanced Microwave Sounding Unit) channels. Interest in this topic was evidenced by the participation of 24 scientists from 16 institutions. An ensemble of 42 diverse atmospheres was used and results compiled for 19 infrared models and 10 microwave models, including several LBL RTMs. For the first time, not only radiances, but also Jacobians (of temperature, water vapor and ozone) were compared to various LBL models for many channels. In the infrared, LBL models typically agree to within 0.05-0.15 K (standard deviation) in terms of top-of-the-atmosphere brightness temperature (BT). Individual differences up to 0.5 K still exist, systematic in some channels, and linked to the type of atmosphere in others. The best fast models emulate LBL BTs to within 0.25 K, but no model achieves this desirable level of success for all channels. The ozone modeling is particularly challenging, In the microwave, fast models generally do quite well against the LBL model to which they were tuned. However significant differences were noted among LBL models, Extending the intercomparison to the Jacobians proved very useful in detecting subtle and more obvious modeling errors. In addition, total and single gas optical depths were calculated, which provided additional insight on the nature of differences. Recommendations for future intercomparisons are suggested.
Radiance and Jacobian Intercomparison of Radiative Transfer Models Applied to HIRS and AMSU Channels
NASA Technical Reports Server (NTRS)
Garand, L.; Turner, D. S.; Larocque, M.; Bates, J.; Boukabara, S.; Brunel, P.; Chevallier, F.; Deblonde, G.; Engelen, R.; Atlas, Robert (Technical Monitor)
2000-01-01
The goals of this study are the evaluation of current fast radiative transfer models (RTMs) and line-by-line (LBL) models. The intercomparison focuses on the modeling of 11 representative sounding channels routinely used at numerical weather prediction centers: seven HIRS (High-resolution Infrared Sounder) and four AMSU (Advanced Microwave Sounding Unit) channels. Interest in this topic was evidenced by the participation of 24 scientists from 16 institutions. An ensemble of 42 diverse atmospheres was used and results compiled for 19 infrared models and 10 microwave models, including several LBL RTMs. For the first time, not only radiances, but also Jacobians (of temperature, water vapor, and ozone) were compared to various LBL models for many channels. In the infrared, LBL models typically agree to within 0.05-0.15 K (standard deviation) in terms of top-of-the-atmosphere brightness temperature (BT). Individual differences up to 0.5 K still exist, systematic in some channels, and linked to the type of atmosphere in others. The best fast models emulate LBL BTs to within 0.25 K, but no model achieves this desirable level of success for all channels. The ozone modeling is particularly challenging. In the microwave, fast models generally do quite well against the LBL model to which they were tuned. However significant differences were noted among LBL models. Extending the intercomparison to the Jacobians proved very useful in detecting subtle and more obvious modeling errors. In addition, total and single gas optical depths were calculated, which provided additional insight on the nature of differences. Recommendations for future intercomparisons are suggested.
NSDL National Science Digital Library
In this activity students use log tapes and base-two slide rules as references to graph exponential functions and log functions in base-10 and base-2. Students discover that exponential and log functions are inverse, reflecting across the y = x axis as mirror images. This is activity E2 in the "Far Out Math" educator's guide. Lessons in the guide include activities in which students measure, compare quantities as orders of magnitude, become familiar with scientific notation, and develop an understanding of exponents and logarithms using examples from NASA's GLAST mission. These are skills needed to understand the very large and very small quantities characteristic of astronomical observations. Note: In 2008, the GLAST mission was renamed Fermi, for the physicist Enrico Fermi.
Efficient Inversion of Mult-frequency and Multi-Source Electromagnetic Data
Gary D. Egbert
2007-03-22
The project covered by this report focused on development of efficient but robust non-linear inversion algorithms for electromagnetic induction data, in particular for data collected with multiple receivers, and multiple transmitters, a situation extremely common in eophysical EM subsurface imaging methods. A key observation is that for such multi-transmitter problems each step in commonly used linearized iterative limited memory search schemes such as conjugate gradients (CG) requires solution of forward and adjoint EM problems for each of the N frequencies or sources, essentially generating data sensitivities for an N dimensional data-subspace. These multiple sensitivities allow a good approximation to the full Jacobian of the data mapping to be built up in many fewer search steps than would be required by application of textbook optimization methods, which take no account of the multiplicity of forward problems that must be solved for each search step. We have applied this idea to a develop a hybrid inversion scheme that combines features of the iterative limited memory type methods with a Newton-type approach using a partial calculation of the Jacobian. Initial tests on 2D problems show that the new approach produces results essentially identical to a Newton type Occam minimum structure inversion, while running more rapidly than an iterative (fixed regularization parameter) CG style inversion. Memory requirements, while greater than for something like CG, are modest enough that even in 3D the scheme should allow 3D inverse problems to be solved on a common desktop PC, at least for modest (~ 100 sites, 15-20 frequencies) data sets. A secondary focus of the research has been development of a modular system for EM inversion, using an object oriented approach. This system has proven useful for more rapid prototyping of inversion algorithms, in particular allowing initial development and testing to be conducted with two-dimensional example problems, before approaching more computationally cumbersome three-dimensional problems.
Dynamic Inversion of Intraslab Intermediate Depth Earthquakes
NASA Astrophysics Data System (ADS)
Madariaga, R. I.; Ruiz, S.
2011-12-01
We perform kinematic and dynamic inversions of the 24 July 2008 (Mw=6.8) Iwate northern Japan and 16 December 2007 (Mw 6.8) Michilla, Chile earthquakes using near field strong motion digital data. The data were filtered between 0.02 - 1 Hz. The rupture process is simulated with elliptical patches because we are looking for the average properties of the seismic rupture. The direct dynamic simulation problem was solved by a combination of finite difference modeling on a 32 km3 grid with 200 m spacing, and propagation from source to recorders using the AXITRA spectral program. For both earthquakes we used layered models of the structure. The Neighborhood algorithm and Monte Carlo methods are used to obtain the best fitting solutions and to explore the solution space. The optimum solutions are found comparing observed and synthetic records using an L2 norm. Both kinematic and dynamic inversions fit the observed data with misfits lower than 0.3. For both earthquakes, kinematic inversion shows strong trade-off between rupture velocity and maximum slip although the seismic moment remains invariant. Rupture velocities vary between sub-shear speeds to almost Rayleigh wave speeds. In the dynamic inversions 10 seismic source parameters were inverted for the Michilla earthquake and 8 parameters for the Iwate event, among them stress, friction and geometrical parameters. For the Iwate event the properties of the initial asperity at the source were not inverted because they could not be resolved by the data. In the dynamic inversion we observed a strong trade off among the friction law parameters. The best dynamic models form a family of that shares similar values of seismic moment and kappa (the ratio of released strain energy to energy release rate for friction). Kinematic and dynamic inversions in the 0.02 - 1 Hz frequency range form a set of non-unique solutions controlled by specific combinations of seismic source parameters. We discuss the origin of the non-uniqueness of the inverse problem.
Possible Supersymmetric Kinematics
Chao-Guang Huang; Lin Li
2014-09-19
The contraction method in different limits to obtain 22 different realizations of kinematical algebras is applied to study the supersymmetric extension of \\AdS\\ algebra and its contractions. It is shown that $\\frak{p}_2$ $\\frak{h}_-$, $\\frak{p}'$, $\\frak{c}_2$ and $\\frak{g}'$ algebras, in addition to $\\frak{d}_-$, $\\frak{p}$, $\\frak{n}_-$, $\\frak{g}$ and $\\frak{c}$ algebras, have supersymmetric extension, while $\\frak{n}_{-2}$, $\\frak{g}_2$ and $\\frak{g}'_2$ algebras have no supersymmetric extension. The connections among the superalgebras are established.
Possible supersymmetric kinematics
NASA Astrophysics Data System (ADS)
Huang, Chao-Guang; Li, Lin
2015-09-01
The contraction method in different limits to obtain 22 different realizations of kinematical algebras is applied to study the supersymmetric extension of AdS algebra and its contractions. It is shown that p2 h, p?, c2 and g? algebras, in addition to d, p, n, g and c algebras, have supersymmetric extension, while n_2, g2 and g?2 algebras have no supersymmetric extension. The connections among the superalgebras are established. Supported by National Natural Science Foundation of China (11275207)
Kinematics and design of a class of parallel manipulators
NASA Astrophysics Data System (ADS)
Hertz, Roger Barry
1998-12-01
This dissertation is concerned with the kinematic analysis and design of a class of three degree-of-freedom, spatial parallel manipulators. The class of manipulators is characterized by two platforms, between which are three legs, each possessing a succession of revolute, spherical, and revolute joints. The class is termed the "revolute-spherical-revolute" class of parallel manipulators. Two members of this class are examined. The first mechanism is a double-octahedral variable-geometry truss, and the second is termed a double tripod. The history the mechanisms is explored---the variable-geometry truss dates back to 1984, while predecessors of the double tripod mechanism date back to 1869. This work centers on the displacement analysis of these three-degree-of-freedom mechanisms. Two types of problem are solved: the forward displacement analysis (forward kinematics) and the inverse displacement analysis (inverse kinematics). The kinematic model of the class of mechanism is general in nature. A classification scheme for the revolute-spherical-revolute class of mechanism is introduced, which uses dominant geometric features to group designs into 8 different sub-classes. The forward kinematics problem is discussed: given a set of independently controllable input variables, solve for the relative position and orientation between the two platforms. For the variable-geometry truss, the controllable input variables are assumed to be the linear (prismatic) joints. For the double tripod, the controllable input variables are the three revolute joints adjacent to the base (proximal) platform. Multiple solutions are presented to the forward kinematics problem, indicating that there are many different positions (assemblies) that the manipulator can assume with equivalent inputs. For the double tripod these solutions can be expressed as a 16th degree polynomial in one unknown, while for the variable-geometry truss there exist two 16th degree polynomials, giving rise to 256 solutions. For special cases of the double tripod, the forward kinematics problem is shown to have a closed-form solution. Numerical examples are presented for the solution to the forward kinematics. A double tripod is presented that admits 16 unique and real forward kinematics solutions. Another example for a variable geometry truss is given that possesses 64 real solutions: 8 for each 16th order polynomial. The inverse kinematics problem is also discussed: given the relative position of the hand (end-effector), which is rigidly attached to one platform, solve for the independently controlled joint variables. Iterative solutions are proposed for both the variable-geometry truss and the double tripod. For special cases of both mechanisms, closed-form solutions are given. The practical problems of designing, building, and controlling a double-tripod manipulator are addressed. The resulting manipulator is a first-of-its kind prototype of a tapered (asymmetric) double-tripod manipulator. Real-time forward and inverse kinematics algorithms on an industrial robot controller is presented. The resulting performance of the prototype is impressive, since it was to achieve a maximum tool-tip speed of 4064 mm/s, maximum acceleration of 5 g, and a cycle time of 1.2 seconds for a typical pick-and-place pattern.
Kinematic capability in the SVDS
NASA Technical Reports Server (NTRS)
Flanders, H. A.
1977-01-01
The details of the Remote Manipulator System kinematic model implemented into the Space Vehicle Dynamics Simulation are given. Detailed engineering flow diagrams and definitions of terms are included.
arXiv:0905.1242v1[math.NT]8May2009 TWO-COVERINGS OF JACOBIANS OF CURVES OF GENUS TWO
Flynn, E. Victor
FLYNN, DAMIANO TESTA, AND RONALD VAN LUIJK Abstract. Given a curve C of genus 2 defined over a field k. Coverings, Jacobians, Homogeneous spaces. 1 #12;2 E. VICTOR FLYNN, DAMIANO TESTA, AND RONALD VAN LUIJK
Kinematics of Strong Discontinuities
NASA Technical Reports Server (NTRS)
Peterson, K.; Nguyen, G.; Sulsky, D.
2006-01-01
Synthetic Aperture Radar (SAR) provides a detailed view of the Arctic ice cover. When processed with the RADARSAT Geophysical Processor System (RGPS), it provides estimates of sea ice motion and deformation over large regions of the Arctic for extended periods of time. The deformation is dominated by the appearance of linear kinematic features that have been associated with the presence of leads. The RGPS deformation products are based on the assumption that the displacement and velocity are smooth functions of the spatial coordinates. However, if the dominant deformation of multiyear ice results from the opening, closing and shearing of leads, then the displacement and velocity can be discontinuous. This presentation discusses the kinematics associated with strong discontinuities that describe possible jumps in displacement or velocity. Ice motion from SAR data are analyzed using this framework. It is assumed that RGPS cells deform due to the presence of a lead. The lead orientation is calculated to optimally account for the observed deformation. It is shown that almost all observed deformation can be represented by lead opening and shearing. The procedure used to reprocess motion data to account for leads will be described and applied to regions of the Beaufort Sea. The procedure not only provides a new view of ice deformation, it can be used to obtain information about the presence of leads for initialization and/or validation of numerical simulations.
Zhu, Lin; Gong, Huili; Gable, Carl; Teatini, Pietro
2015-01-01
Understanding the heterogeneity arising from the complex architecture of sedimentary sequences in alluvial fans is challenging. This paper develops a statistical inverse framework in a multi-zone transition probability approach for characterizing the heterogeneity in alluvial fans. An analytical solution of the transition probability matrix is used to define the statistical relationships among different hydrofacies and their mean lengths, integral scales, and volumetric proportions. A statistical inversion is conducted to identify the multi-zone transition probability models and estimate the optimal statistical parameters using the modified Gauss-Newton-Levenberg-Marquardt method. The Jacobian matrix is computed by the sensitivity equation method, which results in an accurate inverse solution with quantification of parameter uncertainty. We use the Chaobai River alluvial fan in the Beijing Plain, China, as an example for elucidating the methodology of alluvial fan characterization. The alluvial fan is divided...
An inexact Cayley transform method for inverse eigenvalue problems with multiple eigenvalues
NASA Astrophysics Data System (ADS)
Shen, W. P.; Li, C.; Jin, X. Q.
2015-08-01
We consider the convergence problem of an inexact Cayley transform method for solving inverse eigenvalue problems with multiple eigenvalues. Under the nonsingularity assumption of the relative generalized Jacobian matrix at the solution {{c}}*, a convergence analysis covering both the distinct and multiple eigenvalues cases is provided and the superlinear convergence is proved. Moreover, numerical experiments are given in the last section and comparisons with the Cayley transform method are made. This project was supported in part by the National Natural Science Foundations of China (grants 11101379, 11171300, 11371325) and by the grant MYRG098(Y2-L3)-FST13-JXQ from University of Macau.
Kinematical Analysis of an Articulated Mechanism
Fleischfresser, Luciano
2015-01-01
The purpose of this work is twofold: to present mathematical expressions for the kinematics of an articulated mechanism and to perform numerical experiments with the implemented Fortran code. The system of rigid parts is made of two slender bars and a disk. A constant 2 rad/s counterclockwise rotation rate is imposed on the disk triggering the planar motion of the longer bar (link) and the rotation of the shorter one (output). Angular relations, velocities and accelerations are analyzed for a 90-degree turn of the disk. The inversion of the linking bar sense of rotation is well captured by the simulation, and the paper and pencil solutions that may lead to wrong conclusions are explained. Equations are derived from first principles and the Fortran code is placed under version control (currently, v.0.8-beta). This computer project is relevant for those in charge of vector dynamics courses and wishing to expose students to project-based learning activities.
NASA Technical Reports Server (NTRS)
Bryfogle, Mark D.; Nguyen, Charles C.; Antrazi, Sami S.; Chiou, Peter C.
1993-01-01
Design of a parallel force-reflecting hand controller that implements a friction- and inertia canceling control loop about the entire mechanism based on wrench sensing in the mechanism handgrip is discussed. Kinematics of the controller under consideration is analyzed and results are presented using a closed-form solution for the inverse kinematics and Newton-Raphson's method for the forward kinematics. Results indicate that the force control scheme based on a handgrip force sensor provides smaller steady-state errors than the scheme without a handigrip sensor.
Jean-François Lemieux; Stephen F. Price; Katherine J. Evans; Dana Knoll; Andrew G. Salinger; David M. Holland; Antony J. Payne
2011-01-01
We have implemented the Jacobian-free Newton-Krylov (JFNK) method for solving the first-order ice sheet momentum equation in order to improve the numerical performance of the Glimmer-Community Ice Sheet Model (Glimmer-CISM), the land ice component of the Community Earth System Model (CESM). Our JFNK implementation is based on significant re-use of existing code. For example, our physics-based preconditioner uses the original
Robert R. Nourgaliev; Richard C. Martineau; Dana A. Knoll
2008-01-01
We present high-order accurate spatiotemporal discretization of all-speed flow solvers using Jacobian-free Newton Krylov framework. One of the key developments in this work is the physics-based preconditioner for the all-speed flow, which makes use of traditional semi-implicit schemes. The physics-based preconditioner is developed in the primitive variable form, which allows a straightforward separation of physical phenomena. Numerical examples demonstrate that
Ying Chen; Chen Shen
2006-01-01
In this paper, an adaptive preconditioner is constructed for Jacobian-free Newton-GMRES(m) [JFNG(m)] methods, which is devised for solving coordination equations in distributed simulations of power systems. The preconditioner is updated during both Newton iterations and GMRES iterations by means of a rank-one update algorithm. The proposed preconditioned JFNG(m) is applied to power flow calculations for test. The results show that
Luanjing Guo; Chuan Lu; Hai Huang; Derek R. Gaston
2012-01-01
Systems of multicomponent reactive transport in porous media that are large, highly nonlinear, and tightly coupled due to complex nonlinear reactions and strong solution-media interactions are often described by a system of coupled nonlinear partial differential algebraic equations (PDAEs). A preconditioned Jacobian-Free Newton-Krylov (JFNK) solution approach is applied to solve the PDAEs in a fully coupled, fully implicit manner. The
Jean-François Lemieux; Stephen F. Price; Katherine J. Evans; Dana Knoll; Andrew G. Salinger; David M. Holland; Antony J. Payne
2011-01-01
We have implemented the Jacobian-free Newton–Krylov (JFNK) method for solving the first-order ice sheet momentum equation in order to improve the numerical performance of the Glimmer-Community Ice Sheet Model (Glimmer-CISM), the land ice component of the Community Earth System Model (CESM). Our JFNK implementation is based on significant re-use of existing code. For example, our physics-based preconditioner uses the original
Toshio Fukushima
2009-01-01
In order to accelerate the numerical evaluation of torque-free rotation of triaxial rigid bodies, we present a fast method\\u000a to compute various kinds of elliptic functions for a series of the elliptic argument when the elliptic parameter and the elliptic\\u000a characteristic are fixed. The functions we evaluate are the Jacobian elliptic functions and the incomplete elliptic integral\\u000a of the second
An implicit energy-conservative 2D Fokker-Planck algorithm -- 2. Jacobian-free Newton-Krylov solver
Chacon, L.; Barnes, D.C.; Knoll, D.A.; Miley, G.H.
2000-01-20
Energy-conservative implicit integration schemes for the Fokker-Planck transport equation in multidimensional geometries require inverting a dense, non-symmetric matrix (Jacobian), which is very expensive to store and solve using standard solvers. However, these limitations can be overcome with Newton-Krylov iterative techniques, since they can be implemented Jacobian-free (the Jacobian matrix from Newton's algorithm is never formed nor stored to proceed with the iteration), and their convergence can be accelerated by preconditioning the original problem. In this document, the efficient numerical implementation of an implicit energy-conservative scheme for multidimensional Fokker-Planck problems using multigrid-preconditioned Krylov methods is discussed. Results show that multigrid preconditioning is very effective in speeding convergence and decreasing CPU requirements, particularly in fine meshes. The solver is demonstrated on grids up to 128 x 128 points in a 2D cylindrical velocity space ({upsilon}{sub r}, {upsilon}{sub p}) with implicit time steps of the order of the collisional time scale of the problem, {tau}. The method preserves particles exactly, and energy conservation is improved over alternative approaches, particularly in coarse meshes. Typical errors in the total energy over a time period of 10{tau} remain below a percent.
NASA Astrophysics Data System (ADS)
Godoy, William F.; Liu, Xu
2012-06-01
The present study introduces a parallel Jacobian-free Newton Krylov (JFNK) general minimal residual (GMRES) solution for the discretized radiative transfer equation (RTE) in 3D, absorbing, emitting and scattering media. For the angular and spatial discretization of the RTE, the discrete ordinates method (DOM) and the finite volume method (FVM) including flux limiters are employed, respectively. Instead of forming and storing a large Jacobian matrix, JFNK methods allow for large memory savings as the required Jacobian-vector products are rather approximated by semiexact and numerical formulations, for which convergence and computational times are presented. Parallelization of the GMRES solution is introduced in a combined memory-shared/memory-distributed formulation that takes advantage of the fact that only large vector arrays remain in the JFNK process. Results are presented for 3D test cases including a simple homogeneous, isotropic medium and a more complex non-homogeneous, non-isothermal, absorbing-emitting and anisotropic scattering medium with collimated intensities. Additionally, convergence and stability of Gram-Schmidt and Householder orthogonalizations for the Arnoldi process in the parallel GMRES algorithms are discussed and analyzed. Overall, the introduction of JFNK methods results in a parallel, yet scalable to the tested 2048 processors, and memory affordable solution to 3D radiative transfer problems without compromising the accuracy and convergence of a Newton-like solution.
White Dwarf Kinematics vs Mass
Wegg, Christopher
2012-01-01
We have investigated the relationship between the kinematics and mass of young (0.95Msun) are consistent with the expected relative contributions of single star evolution and mergers. We find that the kinematics are consistent with the majority of high-mass white dwarfs being formed through single star evolution.
Kinematically Stabilized Microbubble Actuator Arrays
Xiaosong Wu; Guang Yuan; Yong-Kyu Yoon; Mark G. Allen
2008-01-01
In this paper, the concept, fabrication, and characterization of a kinematically stabilized polymeric microbubble actuator (endoskeletal microbubble actuator) for a pneumatic tactile display application are presented. The kinematic stabilization is achieved by the combination of two polymeric layers with complementary functions: a microcorrugated parylene diaphragm layer as a ldquoskeletonrdquo to provide a directional deflection in a desired axial direction while
Kinematics of Globular Cluster Systems
Aaron J. Romanowsky
2006-09-08
I review the field of globular cluster system (GCS) kinematics, including a brief primer on observational methods. The kinematical structures of spiral galaxy GCSs so far appear to be broadly similar. The inferred rotation and mass profiles of elliptical galaxy halos exhibit a diversity of behaviors, requiring more systematic observational and theoretical studies.
Robust Inversion and Data Compression in Control Allocation
NASA Technical Reports Server (NTRS)
Hodel, A. Scottedward
2000-01-01
We present an off-line computational method for control allocation design. The control allocation function delta = F(z)tau = delta (sub 0) (z) mapping commanded body-frame torques to actuator commands is implicitly specified by trim condition delta (sub 0) (z) and by a robust pseudo-inverse problem double vertical line I - G(z) F(z) double vertical line less than epsilon (z) where G(z) is a system Jacobian evaluated at operating point z, z circumflex is an estimate of z, and epsilon (z) less than 1 is a specified error tolerance. The allocation function F(z) = sigma (sub i) psi (z) F (sub i) is computed using a heuristic technique for selecting wavelet basis functions psi and a constrained least-squares criterion for selecting the allocation matrices F (sub i). The method is applied to entry trajectory control allocation for a reusable launch vehicle (X-33).
Kinematics of coastal deformation
NASA Astrophysics Data System (ADS)
Haines, A. J.; Holt, W. E.
Relating the distributed strain and often complicated styles of faulting in deforming continental lithosphere to relative motion of the oceanic plates has proven difficult. A new method to study the kinematics of continental deformation in Asia has been used by A. J. Haines and W. E. Holt, Geology and Geophysics Division, Department of Scientific and Industrial Research, Wellington, New Zealand.Moment tensor elements from large and moderate-sized earthquakes in Asia over the last 85 years [Molnar and Deng, 1984; Molnar and Lyon-Caen, 1989; Ekstrom and England, 1989; W. E. Holt et al., unpublished manuscript, 1990] have been used to determine strain rates, relative velocities, and relative rotations within the deforming regions of Eastern Tibet, Western Sichuan, and Yunnan. That is, velocities and rotations within a deforming zone can be uniquely determined in a given reference frame if the strains are known everywhere within that zone [Haines, 1982
Ivan G. Avramidi; Guglielmo Fucci
2008-11-03
We develop the kinematics in Matrix Gravity, which is a modified theory of gravity obtained by a non-commutative deformation of General Relativity. In this model the usual interpretation of gravity as Riemannian geometry is replaced by a new kind of geometry, which is equivalent to a collection of Finsler geometries with several Finsler metrics depending both on the position and on the velocity. As a result the Riemannian geodesic flow is replaced by a collection of Finsler flows. This naturally leads to a model in which a particle is described by several mass parameters. If these mass parameters are different then the equivalence principle is violated. In the non-relativistic limit this also leads to corrections to the Newton's gravitational potential. We find the first and second order corrections to the usual Riemannian geodesic flow and evaluate the anomalous nongeodesic acceleration in a particular case of static spherically symmetric background.
Detailed solution to a complex kinematics chain manipulator
March-Leuba, S.; Jansen, J.F.; Kress, R.L.; Babcock, S.M.
1992-12-31
This paper presents a relatively simple method based on planar geometry to analyze the inverse kinematics for closed kinematics chain (CKC) mechanisms. Although the general problem and method of approach are well defined, the study of the inverse kinematics of a closed-chain mechanism is a very complicated one. The current methodology allows closed-form solutions to be found, if a solution exists, for the displacements and velocities of all manipulator joints. Critical design parameters can be identified and optimized by using symbolic models. This paper will focus on planar closed-chain structures extended with a rotational base. However, with open and CKC mechanisms combined in different planes, the extension to the case is straightforward. Further, real-time algorithms are developed that can be handled by existing microprocessor technology. To clarify the methodology, the Soldier Robot Interface Project (SRIP) manipulator is analyzed, and a graphic simulation is presented as a verification of the results. This manipulator has 17 links, 24 one-degree-of-freedom (DOF) joints, and 7 CKC loops working in a plane and a rotational base, which determine its 3 DOFs. The SRIP manipulator allows a decoupled linear motion along the vertical or horizontal directions using only one of its linear actuators. The symbolic solution for the inverse kinematics allows optimization to be performed to further decouple the Cartesian motions by changing link lengths of the manipulator. The conclusion achieved by the optimization is that only two link lengths need to be changed to tune the manipulator for a perfect decoupling at each area of the workspace.
SIAM Annual Mtg. 2010, Pittsburgh Kinematics and
Buechler, Steven
SIAM Annual Mtg. 2010, Pittsburgh Kinematics and Numerical Algebraic Geometry Charles Wampler Motivation: Brief introduction to kinematics Basic polynomial continuation Finding isolated roots Numerical algebraic geometry Dealing with positive-dimensional sets Examples from kinematics Some recent work Software
A Jacobian-free Newton Krylov method for mortar-discretized thermomechanical contact problems
Hansen, Glen
2011-07-20
Multibody contact problems are common within the field of multiphysics simulation. Applications involving thermomechanical contact scenarios are also quite prevalent. Such problems can be challenging to solve due to the likelihood of thermal expansion affecting contact geometry which, in turn, can change the thermal behavior of the components being analyzed. This paper explores a simple model of a light water reactor nuclear fuel rod, which consists of cylindrical pellets of uranium dioxide (UO{sub 2}) fuel sealed within a Zircalloy cladding tube. The tube is initially filled with helium gas, which fills the gap between the pellets and cladding tube. The accurate modeling of heat transfer across the gap between fuel pellets and the protective cladding is essential to understanding fuel performance, including cladding stress and behavior under irradiated conditions, which are factors that affect the lifetime of the fuel. The thermomechanical contact approach developed here is based on the mortar finite element method, where Lagrange multipliers are used to enforce weak continuity constraints at participating interfaces. In this formulation, the heat equation couples to linear mechanics through a thermal expansion term. Lagrange multipliers are used to formulate the continuity constraints for both heat flux and interface traction at contact interfaces. The resulting system of nonlinear algebraic equations are cast in residual form for solution of the transient problem. A Jacobian-free Newton Krylov method is used to provide for fully-coupled solution of the coupled thermal contact and heat equations.
A Jacobian-Free Newton Krylov Method for Mortar-Discretized Thermomechanical Contact Problems
Glen Hansen
2011-07-01
Multibody contact problems are common within the field of multiphysics simulation. Applications involving thermomechanical contact scenarios are also quite prevalent. Such problems can be challenging to solve due to the likelihood of thermal expansion affecting contact geometry which, in turn, can change the thermal behavior of the components being analyzed. This paper explores a simple model of a light water reactor nuclear reactor fuel rod, which consists of cylindrical pellets of uranium dioxide (UO2) fuel sealed within a Zircalloy cladding tube. The tube is initially filled with helium gas, which fills the gap between the pellets and cladding tube. The accurate modeling of heat transfer across the gap between fuel pellets and the protective cladding is essential to understanding fuel performance, including cladding stress and behavior under irradiated conditions, which are factors that affect the lifetime of the fuel. The thermomechanical contact approach developed here is based on the mortar finite element method, where Lagrange multipliers are used to enforce weak continuity constraints at participating interfaces. In this formulation, the heat equation couples to linear mechanics through a thermal expansion term. Lagrange multipliers are used to formulate the continuity constraints for both heat flux and interface traction at contact interfaces. The resulting system of nonlinear algebraic equations are cast in residual form for solution of the transient problem. A Jacobian-free Newton Krylov method is used to provide for fully-coupled solution of the coupled thermal contact and heat equations.
A Jacobian-free Newton Krylov method for mortar-discretized thermomechanical contact problems
NASA Astrophysics Data System (ADS)
Hansen, Glen
2011-07-01
Multibody contact problems are common within the field of multiphysics simulation. Applications involving thermomechanical contact scenarios are also quite prevalent. Such problems can be challenging to solve due to the likelihood of thermal expansion affecting contact geometry which, in turn, can change the thermal behavior of the components being analyzed. This paper explores a simple model of a light water reactor nuclear fuel rod, which consists of cylindrical pellets of uranium dioxide (UO 2) fuel sealed within a Zircalloy cladding tube. The tube is initially filled with helium gas, which fills the gap between the pellets and cladding tube. The accurate modeling of heat transfer across the gap between fuel pellets and the protective cladding is essential to understanding fuel performance, including cladding stress and behavior under irradiated conditions, which are factors that affect the lifetime of the fuel. The thermomechanical contact approach developed here is based on the mortar finite element method, where Lagrange multipliers are used to enforce weak continuity constraints at participating interfaces. In this formulation, the heat equation couples to linear mechanics through a thermal expansion term. Lagrange multipliers are used to formulate the continuity constraints for both heat flux and interface traction at contact interfaces. The resulting system of nonlinear algebraic equations are cast in residual form for solution of the transient problem. A Jacobian-free Newton Krylov method is used to provide for fully-coupled solution of the coupled thermal contact and heat equations.
A Jacobian-free Newton-Krylov algorithm for compressible turbulent fluid flows
NASA Astrophysics Data System (ADS)
Chisholm, Todd T.; Zingg, David W.
2009-05-01
Despite becoming increasingly popular in many branches of computational physics, Jacobian-free Newton-Krylov (JFNK) methods have not become the approach of choice in the solution of the compressible Navier-Stokes equations for turbulent aerodynamic flows. To a degree, this is related to some subtle aspects of JFNK methods that are not well understood, and, if poorly handled, can lead to inefficient and unreliable performance. These are described here, along with strategies for addressing them, leading to an efficient JFNK algorithm for turbulent aerodynamic flows applicable to multi-block structured grids and a one-equation turbulence model. Development of globalization strategies for field-equation turbulence models represents one of the key contributions of the paper. Numerous examples of subsonic and transonic flows over single and multi-element airfoils are presented in order to demonstrate the efficiency and reliability of the algorithm. In addition, a number of guidelines are presented to aid in diagnosing problems with JFNK algorithms.
Implicit Plasma Kinetic Simulation Using The Jacobian-Free Newton-Krylov Method
NASA Astrophysics Data System (ADS)
Taitano, William; Knoll, Dana; Chacon, Luis
2009-11-01
The use of fully implicit time integration methods in kinetic simulation is still area of algorithmic research. A brute-force approach to simultaneously including the field equations and the particle distribution function would result in an intractable linear algebra problem. A number of algorithms have been put forward which rely on an extrapolation in time. They can be thought of as linearly implicit methods or one-step Newton methods. However, issues related to time accuracy of these methods still remain. We are pursuing a route to implicit plasma kinetic simulation which eliminates extrapolation, eliminates phase-space from the linear algebra problem, and converges the entire nonlinear system within a time step. We accomplish all this using the Jacobian-Free Newton-Krylov algorithm. The original research along these lines considered particle methods to advance the distribution function [1]. In the current research we are advancing the Vlasov equations on a grid. Results will be presented which highlight algorithmic details for single species electrostatic problems and coupled ion-electron electrostatic problems. [4pt] [1] H. J. Kim, L. Chac'on, G. Lapenta, ``Fully implicit particle in cell algorithm,'' 47th Annual Meeting of the Division of Plasma Physics, Oct. 24-28, 2005, Denver, CO
Hyperelliptic Jacobians as Billiard Algebra of Pencils of Quadrics: Beyond Poncelet Porisms
Vladimir Dragovic; Milena Radnovic
2008-07-09
The thirty years old programme of Griffiths and Harris of understanding higher-dimensional analogues of Poncelet-type problems and synthetic approach to higher genera addition theorems has been settled and completed in this paper. Starting with the observation of the billiard nature of some classical constructions and configurations, we construct the billiard algebra, that is a group structure on the set T of lines in $R^d$ simultaneously tangent to d-1 quadrics from a given confocal family. Using this tool, the related results of Reid, Donagi and Knoerrer are further developed, realized and simplified. We derive a fundamental property of T: any two lines from this set can be obtained from each other by at most d-1 billiard reflections at some quadrics from the confocal family. We introduce two hierarchies of notions: s-skew lines in T and s-weak Poncelet trajectories, s = -1,0,...,d-2. The interrelations between billiard dynamics, linear subspaces of intersections of quadrics and hyperelliptic Jacobians developed in this paper enabled us to obtain higher-dimensional and higher-genera generalizations of several classical genus 1 results: the Cayley's theorem, the Weyr's theorem, the Griffiths-Harris theorem and the Darboux theorem.
Tetrahedral Element Shape Optimization via the Jacobian Determinant and Condition Number
FREITAG,LORI A.; KNUPP,PATRICK
1999-09-27
We present a new shape measure for tetrahedral elements that is optimal in the sense that it gives the distance of a tetrahedron from the set of inverted elements. This measure is constructed from the condition number of the linear transformation between a unit equilateral tetrahedron and any tetrahedron with positive volume. We use this shape measure to formulate two optimization objective functions that are differentiated by their goal: the first seeks to improve the average quality of the tetrahedral mesh; the second aims to improve the worst-quality element in the mesh. Because the element condition number is not defined for tetrahedral with negative volume, these objective functions can be used only when the initial mesh is valid. Therefore, we formulate a third objective function using the determinant of the element Jacobian that is suitable for mesh untangling. We review the optimization techniques used with each objective function and present experimental results that demonstrate the effectiveness of the mesh improvement and untangling methods. We show that a combined optimization approach that uses both condition number objective functions obtains the best-quality meshes.
Uncertainty Quantification of Kinematic Source Parameters using a Bayesian Approach
NASA Astrophysics Data System (ADS)
Razafindrakoto, H.; Mai, M.
2012-04-01
Ground-motion simulations for seismic hazard analysis and dynamic rupture modeling suffer not only from the non-uniqueness of kinematic source models but also from the unknown robustness of source-inversion solutions. Therefore, adequate uncertainty analysis of kinematic source model parameters is critical to better understand the main factors that lead to rupture model variability, and to explore the robustness of kinematic source model parameters. Thanks to large improvements in computational tools, Bayesian techniques have become feasible to estimate comprehensive model uncertainties by producing the probability density functions (PDF) of model parameters. In this study, we use a Bayesian technique to infer the ensemble of all possible source models that are consistent with seismological data and the available prior information. Two different procedures are followed. In the first one, we use a two-step procedure that initially explores the parameter space in search for the best fitting model (using a non-linear optimization algorithm) and then applies a Markov Chain Monte Carlo (MCMC) method for Bayesian inference on the kinematic rupture parameters. The second procedure is a one-step procedure that immediately applies MCMC by assuming Gaussian uncertainty for the seismological data. This second technique is computationally cheaper and explores the full parameter space, but does not provide a best-fitting "reference solution". Our study presents synthetic tests based on the "Source Inversion Validation" (SIV) exercise. We analyze the performance of those two approaches in terms of efficiency, and their ability to image the known kinematic rupture details. For the two-step procedure, we additionally perform jackknife tests to examine the robust and sensitive features of the best-fitting model. Our results indicate that the well-resolved part of the fault is conserved through all the delete-one jackknife tests, and that the posterior PDF follows a Gaussian like distribution only within the well-resolved regions of the fault.
Clifford Algebras and Possible Kinematics
Alan McRae
2007-07-19
We review Bacry and Levy-Leblond's work on possible kinematics as applied to 2-dimensional spacetimes, as well as the nine types of 2-dimensional Cayley-Klein geometries, illustrating how the Cayley-Klein geometries give homogeneous spacetimes for all but one of the kinematical groups. We then construct a two-parameter family of Clifford algebras that give a unified framework for representing both the Lie algebras as well as the kinematical groups, showing that these groups are true rotation groups. In addition we give conformal models for these spacetimes.
Kinematics, controls, and path planning results for a redundant manipulator
NASA Technical Reports Server (NTRS)
Gretz, Bruce; Tilley, Scott W.
1989-01-01
The inverse kinematics solution, a modal position control algorithm, and path planning results for a 7 degree of freedom manipulator are presented. The redundant arm consists of two links with shoulder and elbow joints and a spherical wrist. The inverse kinematics problem for tip position is solved and the redundant joint is identified. It is also shown that a locus of tip positions exists in which there are kinematic limitations on self-motion. A computationally simple modal position control algorithm has been developed which guarantees a nearly constant closed-loop dynamic response throughout the workspace. If all closed-loop poles are assigned to the same location, the algorithm can be implemented with very little computation. To further reduce the required computation, the modal gains are updated only at discrete time intervals. Criteria are developed for the frequency of these updates. For commanding manipulator movements, a 5th-order spline which minimizes jerk provides a smooth tip-space path. Schemes for deriving a corresponding joint-space trajectory are discussed. Modifying the trajectory to avoid joint torque saturation when a tip payload is added is also considered. Simulation results are presented.
Deformation field validation and inversion applied to adaptive radiation therapy
NASA Astrophysics Data System (ADS)
Vercauteren, Tom; De Gersem, Werner; Olteanu, Luiza A. M.; Madani, Indira; Duprez, Fréderic; Berwouts, Dieter; Speleers, Bruno; De Neve, Wilfried
2013-08-01
Development and implementation of chronological and anti-chronological adaptive dose accumulation strategies in adaptive intensity-modulated radiation therapy (IMRT) for head-and-neck cancer. An algorithm based on Newton iterations was implemented to efficiently compute inverse deformation fields (DFs). Four verification steps were performed to ensure a valid dose propagation: intra-cell folding detection finds zero or negative Jacobian determinants in the input DF; inter-cell folding detection is implemented on the resolution of the output DF; a region growing algorithm detects undefined values in the output DF; DF domains can be composed and displayed on the CT data. In 2011, one patient with nonmetastatic head and neck cancer selected from a three phase adaptive DPBN study was used to illustrate the algorithms implemented for adaptive chronological and anti-chronological dose accumulation. The patient received three 18F-FDG-PET/CTs prior to each treatment phase and one CT after finalizing treatment. Contour propagation and DF generation between two consecutive CTs was performed in Atlas-based autosegmentation (ABAS). Deformable image registration based dose accumulations were performed on CT1 and CT4. Dose propagation was done using combinations of DFs or their inversions. We have implemented a chronological and anti-chronological dose accumulation algorithm based on DF inversion. Algorithms were designed and implemented to detect cell folding.
Interactive Physics Lab on Kinematics
Ed Chi; Jeff McKinney; Keri Rouse
2003-01-01
In this activity students will be utilizing an Interactive Physics interactive lab on kinematics. Students will observe how reaction rate is affected by temperature, concentration, surface area and a catalyst.
Error analysis and optimization of a 3-degree of freedom translational Parallel Kinematic Machine
NASA Astrophysics Data System (ADS)
Shankar Ganesh, S.; Koteswara Rao, A. B.
2014-06-01
In this paper, error modeling and analysis of a typical 3-degree of freedom translational Parallel Kinematic Machine is presented. This mechanism provides translational motion along the Cartesian X-, Y- and Z-axes. It consists of three limbs each having an arm and forearm with prismatic-revolute-revolute-revolute joints. The moving or tool platform maintains same orientation in the entire workspace due to its joint arrangement. From inverse kinematics, the joint angles for a given position of tool platform necessary for the error modeling and analysis are obtained. Error modeling is done based on the differentiation of the inverse kinematic equations. Variation of pose errors along X, Y and Z directions for a set of dimensions of the parallel kinematic machine is presented. A non-dimensional performance index, namely, global error transformation index is used to study the influence of dimensions and its corresponding global maximum pose error is reported. An attempt is made to find the optimal dimensions of the Parallel Kinematic Machine using Genetic Algorithms in MATLAB. The methodology presented and the results obtained are useful for predicting the performance capability of the Parallel Kinematic Machine under study.
Kinematic analysis of a flexible six-DOF parallel mechanism.
Jing, Feng-Shui; Tan, Min; Hou, Zeng-Guang; Liang, Zi-Ze; Wang, Yun-Kuan; Gupta, Madan M; Nikiforuk, Peter N
2006-04-01
In this paper, a new type of six-degrees of freedom (DOF) flexible parallel mechanism (FPM) is presented. This type of parallel mechanism possesses several favorable properties: (1) its number of DOFs is independent of the number of serial chains which make up the mechanism; (2) it has no kinematical singularities; (3) it is designed to move on rails, and therefore its workspace is much larger than that of a conventional parallel manipulator; and (4) without changing the number of DOFs and the kinematics of the mechanisms, the number of the serial chains can be reconfigured according to the needs of the tasks. These properties make the mechanism very preferable in practice, especially for such tasks as joining huge ship blocks, in which the manipulated objects vary dramatically both in weights and dimensions. Furthermore, the mechanism can be used as either a fully actuated system or an underactuated system. In the fully actuated case, the mechanism has six DOF motion capabilities and manipulation capabilities. However, in the underactuated case, the mechanism still has six DOF motion capabilities, but it has only five DOF manipulation capabilities. In this paper, both the inverse and forward kinematics are studied and expressed in a closed form. The workspace and singularity analysis of the mechanism are also presented. An example is presented to illustrate how to calculate the kinematics of the mechanism in both fully-actuated and underactuated cases. Finally, an application of such a mechanism to manufacturing industry is introduced. PMID:16602597
Modeling long-period noise in kinematic GPS applications
NASA Astrophysics Data System (ADS)
Borsa, Adrian A.; Minster, Jean-Bernard; Bills, Bruce G.; Fricker, Helen A.
2007-02-01
We develop and test an algorithm for modeling and removing elevation error in kinematic GPS trajectories in the context of a kinematic GPS survey of the salar de Uyuni, Bolivia. Noise in the kinematic trajectory ranges over 15 cm and is highly autocorrelated, resulting in significant contamination of the topographic signal. We solve for a noise model using crossover differences at trajectory intersections as constraints in a least-squares inversion. Validation of the model using multiple realizations of synthetic/simulated noise shows an average decrease in root-mean-square-error (RMSE) by a factor of four. Applying the model to data from the salar de Uyuni survey, we find that crossover differences drop by a factor of eight (from an RMSE of 5.6 to 0.7 cm), and previously obscured topographic features are revealed in a plan view of the corrected trajectory. We believe that this algorithm can be successfully adapted to other survey methods that employ kinematic GPS for positioning.
John F. Donoghue; Daniel Wyler
2009-08-31
We discuss the kinematics of the particles that make up a Reggeon in field theory, using the terminology of the Soft Collinear Effective Theory (SCET). Reggeization sums a series of strongly-ordered collinear emissions resulting in an overall Reggeon exchange that falls in the Glauber or Coulomb kinematic region. This is an extremely multi-scale problem and appears to fall outside of the usual organizing scheme of SCET.
Kinematics of a New High Precision Three Degree-of-Freedom Parallel Manipulator
NASA Technical Reports Server (NTRS)
Tahmasebi, Farhad
2005-01-01
Closed-form direct and inverse kinematics of a new three degree-of-freedom (DOF) parallel manipulator with inextensible limbs and base-mounted actuators are presented. The manipulator has higher resolution and precision than the existing three DOF mechanisms with extensible limbs. Since all of the manipulator actuators are base-mounted; higher payload capacity, smaller actuator sizes, and lower power dissipation can be obtained. The manipulator is suitable for alignment applications where only tip, tilt, and piston motions are significant. The direct kinematics of the manipulator is reduced to solving an eighth-degree polynomial in the square of tangent of half-angle between one of the limbs and the base plane. Hence, there are at most sixteen assembly configurations for the manipulator. In addition, it is shown that the sixteen solutions are eight pairs of reflected configurations with respect to the base plane. Numerical examples for the direct and inverse kinematics of the manipulator are also presented.
Kinematics of Galaxies Spectral Features of Galaxies
Crenshaw, Michael
1 Kinematics of Galaxies · Spectral Features of Galaxies · Basics of Spectroscopy · Elliptical Kinematics · Faber-Jackson and the Fundamental Plane · Disk Kinematics (Stellar and H I) · 2D Velocity Fields triplet lines at ~8500 Å are good for kinematics (well separated, uncontaminated) (Sparke and Gallagher, p
FORWARD KINEMATICS: THE DENAVIT-HARTENBERG
Baltes, Jacky
Chapter 3 FORWARD KINEMATICS: THE DENAVIT-HARTENBERG CONVENTION In this chapter we develop the forward or configuration kinematic equations for rigid robots. The forward kinematics problem is concerned of the tool or end-effector. Stated more formally, the forward kinematics problem is to determine the position
Aero-optimum hovering kinematics.
Nabawy, Mostafa R A; Crowther, William J
2015-08-01
Hovering flight for flapping wing vehicles requires rapid and relatively complex reciprocating movement of a wing relative to a stationary surrounding fluid. This note develops a compact analytical aero-kinematic model that can be used for optimization of flapping wing kinematics against aerodynamic criteria of effectiveness (maximum lift) and efficiency (minimum power for a given amount of lift). It can also be used to make predictions of required flapping frequency for a given geometry and basic aerodynamic parameters. The kinematic treatment is based on a consolidation of an existing formulation that allows explicit derivation of flapping velocity for complex motions whereas the aerodynamic model is based on existing quasi-steady analysis. The combined aero-kinematic model provides novel explicit analytical expressions for both lift and power of a hovering wing in a compact form that enables exploration of a rich kinematic design space. Good agreement is found between model predictions of flapping frequency and observed results for a number of insects and optimal hovering kinematics identified using the model are consistent with results from studies using higher order computational models. For efficient flight, the flapping angle should vary using a triangular profile in time leading to a constant velocity flapping motion, whereas for maximum effectiveness the shape of variation should be sinusoidal. For both cases the wing pitching motion should be rectangular such that pitch change at stroke reversal is as rapid as possible. PMID:26248884
HyeongKae Park; Robert R. Nourgaliev; Richard C. Martineau; Dana A. Knoll
2008-09-01
We present high-order accurate spatiotemporal discretization of all-speed flow solvers using Jacobian-free Newton Krylov framework. One of the key developments in this work is the physics-based preconditioner for the all-speed flow, which makes use of traditional semi-implicit schemes. The physics-based preconditioner is developed in the primitive variable form, which allows a straightforward separation of physical phenomena. Numerical examples demonstrate that the developed preconditioner effectively reduces the number of the Krylov iterations, and the efficiency is independent of the Mach number and mesh sizes under a fixed CFL condition.
A global approach for using kinematic redundancy to minimize base reactions of manipulators
NASA Technical Reports Server (NTRS)
Chung, C. L.; Desa, S.
1989-01-01
An important consideration in the use of manipulators in microgravity environments is the minimization of the base reactions, i.e. the magnitude of the force and the moment exerted by the manipulator on its base as it performs its tasks. One approach which was proposed and implemented is to use the redundant degree of freedom in a kinematically redundant manipulator to plan manipulator trajectories to minimize base reactions. A global approach was developed for minimizing the magnitude of the base reactions for kinematically redundant manipulators which integrates the Partitioned Jacobian method of redundancy resolution, a 4-3-4 joint-trajectory representation and the minimization of a cost function which is the time-integral of the magnitude of the base reactions. The global approach was also compared with a local approach developed earlier for the case of point-to-point motion of a three degree-of-freedom planar manipulator with one redundant degree-of-freedom. The results show that the global approach is more effective in reducing and smoothing the base force while the local approach is superior in reducing the base moment.
Reconstruction procedures for two inverse scattering problems without the phase information
Michael V. Klibanov; Vladimir G. Romanov
2015-05-08
This is a continuation of two recent publications of the authors about reconstruction procedures for 3-d phaseless inverse scattering problems. The main novelty of this paper is that the Born approximation for the case of the wave-like equation is not considered. It is shown here that the phaseless inverse scattering problem for the 3-d wave-like equation in the frequency domain leads to the well known Inverse Kinematic Problem. Uniqueness theorem follows. Still, since the Inverse Kinematic Problem is very hard to solve, a linearization is applied. More precisely, geodesic lines are replaced with straight lines. As a result, an approximate explicit reconstruction formula is obtained via the inverse Radon transform. The second reconstruction method is via solving a problem of the integral geometry using integral equations of the Abel type.
Locative Inversion in Cantonese.
ERIC Educational Resources Information Center
Mok, Sui-Sang
This study investigates the phenomenon of "Locative Inversion" in Cantonese. The term "Locative Inversion" indicates that the locative phrase (LP) syntactic process in Cantonese and the appears at the sentence-initial position and its logical subject occurs postverbally. It is demonstrated that this Locative Inversion is a widespread syntactic…
Solving coupled groundwater flow systems using a Jacobian Free Newton Krylov method
NASA Astrophysics Data System (ADS)
Mehl, S.
2012-12-01
Jacobian Free Newton Kyrlov (JFNK) methods can have several advantages for simulating coupled groundwater flow processes versus conventional methods. Conventional methods are defined here as those based on an iterative coupling (rather than a direct coupling) and/or that use Picard iteration rather than Newton iteration. In an iterative coupling, the systems are solved separately, coupling information is updated and exchanged between the systems, and the systems are re-solved, etc., until convergence is achieved. Trusted simulators, such as Modflow, are based on these conventional methods of coupling and work well in many cases. An advantage of the JFNK method is that it only requires calculation of the residual vector of the system of equations and thus can make use of existing simulators regardless of how the equations are formulated. This opens the possibility of coupling different process models via augmentation of a residual vector by each separate process, which often requires substantially fewer changes to the existing source code than if the processes were directly coupled. However, appropriate perturbation sizes need to be determined for accurate approximations of the Frechet derivative, which is not always straightforward. Furthermore, preconditioning is necessary for reasonable convergence of the linear solution required at each Kyrlov iteration. Existing preconditioners can be used and applied separately to each process which maximizes use of existing code and robust preconditioners. In this work, iteratively coupled parent-child local grid refinement models of groundwater flow and groundwater flow models with nonlinear exchanges to streams are used to demonstrate the utility of the JFNK approach for Modflow models. Use of incomplete Cholesky preconditioners with various levels of fill are examined on a suite of nonlinear and linear models to analyze the effect of the preconditioner. Comparisons of convergence and computer simulation time are made using conventional iteratively coupled methods and those based on Picard iteration to those formulated with JFNK to gain insights on the types of nonlinearities and system features that make one approach advantageous. Results indicate that nonlinearities associated with stream/aquifer exchanges are more problematic than those resulting from unconfined flow.
KINEMATIC ANALYSIS OF MODULAR, TRUSS-BASED MANIPULATOR UNITS
Salerno, R. J.
1994-06-01
Decontamination and Dismantling (D&D) activities within the U.S. Department of Energy (DOE) require a long reach manipulator with a large load capacity. Variable Geometry Trusses (VGTs) are a unique class of mechanical structures which allow the advantages of truss structures for large scale applications to be applied to large robotic manipulators. Individual VGT units may be assembled to create a modular, long-reach, truss-type manipulator. Each module of such a manipulator system is either a static truss section or one of several possible VGT geometries. While many potential applications exist for this technology, the present work is largely motivated by the need for generic robotic systems for remote manipulation. A manipulator system based on VGT modules provides several advantages. The reconfigurable nature of the manipulator system allows it to be adapted on site to unforeseen conditions. The kinematic redundancy of the manipulator enables it to work effectively even in a highly obstructed workspace. The parallel structure of the truss modules enables the manipulator to be withdrawn in the event of a structural failure. Finally, the open framework of the modules provides a clear, protected passageway for control and power cabling, waste conveyance, or other services required at the end effector. As is implied in a truss structure, all primary members of a VGT are ideally loaded in pure tension or compression. This results in an extremely stiff and strong manipulator system with minimal overall weight. Careful design of the joints of a VGT is very important to the overall stiffness and accuracy of the structure, as several links (as many as six) are joined together at each joint. The greatest disadvantage to this approach to manipulator design has traditionally been that the kinematics of VGT structures are complex and poorly understood. This report specifically addresses the kinematics of several possible geometries for the individual VGT units. Equations and solution techniques are developed for solving the "forward" or "direct" and "inverse" kinematic problems for these geometries. The" forward" kinematic problem is that of finding the position and orientation of the distal end of the VGT relative to the proximal end, given the specific displacements of the (linear) actuators. This problem is rarely solvable in closed form. However, powerful iterative algorithms capable of solution in real time on typical modern robot control hardware are presented. The "inverse" kinematic problem is that of finding the required actuator displacements given the position and orientation of the distal end of the VGT relative to the proximal end. For specific VGT geometries, closed-form solutions are presented. For the more general problem, iterative algorithms capable of solution in real time are again derived and presented.
Christensen, Gary E.; Song, Joo Hyun; Lu, Wei; Naqa, Issam El; Low, Daniel A.
2007-06-15
Breathing motion is one of the major limiting factors for reducing dose and irradiation of normal tissue for conventional conformal radiotherapy. This paper describes a relationship between tracking lung motion using spirometry data and image registration of consecutive CT image volumes collected from a multislice CT scanner over multiple breathing periods. Temporal CT sequences from 5 individuals were analyzed in this study. The couch was moved from 11 to 14 different positions to image the entire lung. At each couch position, 15 image volumes were collected over approximately 3 breathing periods. It is assumed that the expansion and contraction of lung tissue can be modeled as an elastic material. Furthermore, it is assumed that the deformation of the lung is small over one-fifth of a breathing period and therefore the motion of the lung can be adequately modeled using a small deformation linear elastic model. The small deformation inverse consistent linear elastic image registration algorithm is therefore well suited for this problem and was used to register consecutive image scans. The pointwise expansion and compression of lung tissue was measured by computing the Jacobian of the transformations used to register the images. The logarithm of the Jacobian was computed so that expansion and compression of the lung were scaled equally. The log-Jacobian was computed at each voxel in the volume to produce a map of the local expansion and compression of the lung during the breathing period. These log-Jacobian images demonstrate that the lung does not expand uniformly during the breathing period, but rather expands and contracts locally at different rates during inhalation and exhalation. The log-Jacobian numbers were averaged over a cross section of the lung to produce an estimate of the average expansion or compression from one time point to the next and compared to the air flow rate measured by spirometry. In four out of five individuals, the average log-Jacobian value and the air flow rate correlated well (R{sup 2}=0.858 on average for the entire lung). The correlation for the fifth individual was not as good (R{sup 2}=0.377 on average for the entire lung) and can be explained by the small variation in tidal volume for this individual. The correlation of the average log-Jacobian value and the air flow rate for images near the diaphragm correlated well in all five individuals (R{sup 2}=0.943 on average). These preliminary results indicate a strong correlation between the expansion/compression of the lung measured by image registration and the air flow rate measured by spirometry. Predicting the location, motion, and compression/expansion of the tumor and normal tissue using image registration and spirometry could have many important benefits for radiotherapy treatment. These benefits include reducing radiation dose to normal tissue, maximizing dose to the tumor, improving patient care, reducing treatment cost, and increasing patient throughput.
Dana A. Knoll; H. Park; Kord Smith
2011-02-01
The use of the Jacobian-free Newton-Krylov (JFNK) method within the context of nonlinear diffusion acceleration (NDA) of source iteration is explored. The JFNK method is a synergistic combination of Newton's method as the nonlinear solver and Krylov methods as the linear solver. JFNK methods do not form or store the Jacobian matrix, and Newton's method is executed via probing the nonlinear discrete function to approximate the required matrix-vector products. Current application of NDA relies upon a fixed-point, or Picard, iteration to resolve the nonlinearity. We show that the JFNK method can be used to replace this Picard iteration with a Newton iteration. The Picard linearization is retained as a preconditioner. We show that the resulting JFNK-NDA capability provides benefit in some regimes. Furthermore, we study the effects of a two-grid approach, and the required intergrid transfers when the higher-order transport method is solved on a fine mesh compared to the low-order acceleration problem.
Clifford Fibrations and Possible Kinematics
NASA Astrophysics Data System (ADS)
McRae, Alan S.
2009-07-01
Following Herranz and Santander [Herranz F.J., Santander M., Mem. Real Acad. Cienc. Exact. Fis. Natur. Madrid 32 (1998), 59-84, physics/9702030] we will construct homogeneous spaces based on possible kinematical algebras and groups [Bacry H., Levy-Leblond J.-M., J. Math. Phys. 9 (1967), 1605-1614] and their contractions for 2-dimensional spacetimes. Our construction is different in that it is based on a generalized Clifford fibration: Following Penrose [Penrose R., Alfred A. Knopf, Inc., New York, 2005] we will call our fibration a Clifford fibration and not a Hopf fibration, as our fibration is a geometrical construction. The simple algebraic properties of the fibration describe the geometrical properties of the kinematical algebras and groups as well as the spacetimes that are derived from them. We develop an algebraic framework that handles all possible kinematic algebras save one, the static algebra.
Clifford Fibrations and Possible Kinematics
Alan S. McRae
2009-07-14
Following Herranz and Santander [Herranz F.J., Santander M., Mem. Real Acad. Cienc. Exact. Fis. Natur. Madrid 32 (1998), 59-84, physics/9702030] we will construct homogeneous spaces based on possible kinematical algebras and groups [Bacry H., Levy-Leblond J.-M., J. Math. Phys. 9 (1967), 1605-1614] and their contractions for 2-dimensional spacetimes. Our construction is different in that it is based on a generalized Clifford fibration: Following Penrose [Penrose R., Alfred A. Knopf, Inc., New York, 2005] we will call our fibration a Clifford fibration and not a Hopf fibration, as our fibration is a geometrical construction. The simple algebraic properties of the fibration describe the geometrical properties of the kinematical algebras and groups as well as the spacetimes that are derived from them. We develop an algebraic framework that handles all possible kinematic algebras save one, the static algebra.
Kinematics and dynamics of robotic systems with multiple closed loops
NASA Astrophysics Data System (ADS)
Zhang, Chang-De
The kinematics and dynamics of robotic systems with multiple closed loops, such as Stewart platforms, walking machines, and hybrid manipulators, are studied. In the study of kinematics, focus is on the closed-form solutions of the forward position analysis of different parallel systems. A closed-form solution means that the solution is expressed as a polynomial in one variable. If the order of the polynomial is less than or equal to four, the solution has analytical closed-form. First, the conditions of obtaining analytical closed-form solutions are studied. For a Stewart platform, the condition is found to be that one rotational degree of freedom of the output link is decoupled from the other five. Based on this condition, a class of Stewart platforms which has analytical closed-form solution is formulated. Conditions of analytical closed-form solution for other parallel systems are also studied. Closed-form solutions of forward kinematics for walking machines and multi-fingered grippers are then studied. For a parallel system with three three-degree-of-freedom subchains, there are 84 possible ways to select six independent joints among nine joints. These 84 ways can be classified into three categories: Category 3:3:0, Category 3:2:1, and Category 2:2:2. It is shown that the first category has no solutions; the solutions of the second category have analytical closed-form; and the solutions of the last category are higher order polynomials. The study is then extended to a nearly general Stewart platform. The solution is a 20th order polynomial and the Stewart platform has a maximum of 40 possible configurations. Also, the study is extended to a new class of hybrid manipulators which consists of two serially connected parallel mechanisms. In the study of dynamics, a computationally efficient method for inverse dynamics of manipulators based on the virtual work principle is developed. Although this method is comparable with the recursive Newton-Euler method for serial manipulators, its advantage is more noteworthy when applied to parallel systems. An approach of inverse dynamics of a walking machine is also developed, which includes inverse dynamic modeling, foot force distribution, and joint force/torque allocation. inverse dynamic modeling of a quadruped with pantograph legs is derived. The inverse dynamics of this quadruped walking in different wave gaits is then studied.
NASA Astrophysics Data System (ADS)
Repetto, P.; Rosado, M.; Gabbasov, R.; Fuentes-Carrera, I.
2010-06-01
In this work we present scanning Fabry-Perot H? observations of the isolated interacting galaxy pair NGC 5278/9 obtained with the PUMA Fabry-Perot interferometer. We derived velocity fields, various kinematic parameters and rotation curves for both galaxies. Our kinematical results together with the fact that dust lanes have been detected in both galaxies, as well as the analysis of surface brightness profiles along the minor axis, allowed us to determine that both components of the interacting pair are trailing spirals.
Emergent gravity requires kinematic nonlocality.
Marolf, Donald
2015-01-23
This Letter refines arguments forbidding nonlinear dynamical gravity from appearing in the low energy effective description of field theories with local kinematics, even for those with instantaneous long-range interactions. Specifically, we note that gravitational theories with universal coupling to energy-an intrinsically nonlinear phenomenon-are characterized by Hamiltonians that are pure boundary terms on shell. In order for this to be the low energy effective description of a field theory with local kinematics, all bulk dynamics must be frozen and, thus, irrelevant to the construction. The result applies to theories defined either on a lattice or in the continuum, and requires neither Lorentz invariance nor translation invariance. PMID:25658991
Deformable templates using large deformation kinematics
Gary E. Christensen; Richard D. Rabbitt; Michael I. Miller
1996-01-01
A general automatic approach is presented for accommodating local shape variation when mapping a two-dimensional (2-D) or three-dimensional (3-D) template image into alignment with a topologically similar target image. Local shape variability is accommodated by applying a vector-field transformation to the underlying material coordinate system of the template while constraining the transformation to be smooth (globally positive definite Jacobian). Smoothness
NASA Technical Reports Server (NTRS)
Nguyen, Charles C.; Pooran, Farhad J.
1989-01-01
This report presents results from the research grant entitled Active Control of Robot Manipulators, funded by the Goddard Space Flight Center, under Grant NAG5-780, for the period July 1, 1988 to January 1, 1989. An analysis is presented of a 6 degree-of-freedom robot end-effector built to study telerobotic assembly of NASA hardware in space. Since the end-effector is required to perform high precision motion in a limited workspace, closed-kinematic mechanisms are chosen for its design. A closed-form solution is obtained for the inverse kinematic problem and an iterative procedure employing Newton-Raphson method is proposed to solve the forward kinematic problem. A study of the end-effector workspace results in a general procedure for the workspace determination based on link constraints. Computer simulation results are presented.
Kinematics and trajectory generation for MIRADAS arms
NASA Astrophysics Data System (ADS)
Sabater, J.; Gómez, J. M.; Torra, J.; López, M.; Raines, S. N.; Eikenberry, S. S.
2015-05-01
The Mid-resolution InfRAreD Astronomical Spectrograph (MIRADAS) is a NIR multi-object spectrograph for the Gran Telescopio Canarias (GTC). The instrument has a multiplexing system (MXS) that enables the simultaneous observation of twenty objects located within its field of view. These user selected targets are acquired by twenty deployable robotic probe arms with pickoff mirror optics operating at cryogenic temperatures. The MIRADAS probe arm is a close-loop mechanism designed with optics simplicity in mind, presenting good stability when it is operated upside down. Calculating optimum collision-free trajectories requires a good knowledge of the MIRADAS arm behavior based on its geometry and its mechanical constraints. This study introduces a geometric model for the two degree-of-freedom (DoF) mechanism, including solutions for the forward and inverse kinematics problem. The concepts of zone-of-avoidance (ZoA), workspace and envelope of MIRADAS arm are presented and studied. Finally, the paper proposes two different patrolling approaches that can be exploited when planning trajectories.
Barberis, Emanuela; /Northeastern U.
2006-05-01
A summary of the results on the measurement of the Top Quark mass and the study of the kinematics of the t{bar t} system at the Tevatron collider is presented here. Results from both the CDF and D0 collaborations are reported.
Kinematics of the western Mediterranean
J. F. Dewey; M. L. Helman; S. D. Knott; E. Turco; D. H. W. Hutton
1989-01-01
I I SUMMARY: The kinematic understanding of the relationship between relative plate motion and the structure of orogenic belts depends upon a knowledge of relative plate motion across the plate boundary system, the relative motion of small blocks and flakes within the system, an evaluation of orogenic body forces, and an understanding of the thermomechanical evolution of the upper part
Kinematic and stability motion limits for a hexapod walking machine
NASA Astrophysics Data System (ADS)
Dunton, Elizabeth M.
1995-03-01
The major problem addressed by this research is to investigate and implement the basic concepts necessary to lay the groundwork for efficient forms of motion planning, motion control, and gait algorithms with respect to hexapod walking machines. Specifically, the approach taken was to develop and implement the concepts of a stability margin and a joint space motion margin on an object-oriented representation of the Aquarobot. The model was generated in Franz Common Lisp and simulated via Allegro Common Windows. A method by which distance computations can be calculated and applied to the center of mass and triangular support pattern of a walking machine to determine the stability margin is introduced. Inverse kinematics and joint limits are utilized to ascertain the joint space motion margin of the model. Response to impending instability and the effect when a joint hits or approaches a joint kinematic limit on the motion of the hexapod walking machine by stopping the model is also addressed. The results are as follows: the concepts of the joint space motion margin and the stability margin can be successfully implemented on a kinematic model and graphical simulation of a hexapod walking machine. These concepts contribute to future work in the area of more efficient free gait algorithms, specifically asynchronous gait algorithms.
Analysis of a closed-kinematic chain robot manipulator
NASA Technical Reports Server (NTRS)
Nguyen, Charles C.; Pooran, Farhad J.
1988-01-01
Presented are the research results from the research grant entitled: Active Control of Robot Manipulators, sponsored by the Goddard Space Flight Center (NASA) under grant number NAG-780. This report considers a class of robot manipulators based on the closed-kinematic chain mechanism (CKCM). This type of robot manipulators mainly consists of two platforms, one is stationary and the other moving, and they are coupled together through a number of in-parallel actuators. Using spatial geometry and homogeneous transformation, a closed-form solution is derived for the inverse kinematic problem of the six-degree-of-freedom manipulator, built to study robotic assembly in space. Iterative Newton Raphson method is employed to solve the forward kinematic problem. Finally, the equations of motion of the above manipulators are obtained by employing the Lagrangian method. Study of the manipulator dynamics is performed using computer simulation whose results show that the robot actuating forces are strongly dependent on the mass and centroid locations of the robot links.
Singularity-theoretic methods in robot kinematics
Donelan, Peter
Singularity-theoretic methods in robot kinematics P. S. Donelan School of Mathematics, Statistics-theoretic methods in robot kinematics and presents some new results. Keywords: Singularity theory; Robot manipulator, subject to constraints such as closed loops. For a serial manipulator, the forward (direct) kinematics
NASA Astrophysics Data System (ADS)
Büsing, Henrik
2013-04-01
Two-phase flow in porous media occurs in various settings, such as the sequestration of CO2 in the subsurface, radioactive waste management, the flow of oil or gas in hydrocarbon reservoirs, or groundwater remediation. To model the sequestration of CO2, we consider a fully coupled formulation of the system of nonlinear, partial differential equations. For the solution of this system, we employ the Box method after Huber & Helmig (2000) for the space discretization and the fully implicit Euler method for the time discretization. After linearization with Newton's method, it remains to solve a linear system in every Newton step. We compare different iterative methods (BiCGStab, GMRES, AGMG, c.f., [Notay (2012)]) combined with different preconditioners (ILU0, ASM, Jacobi, and AMG as preconditioner) for the solution of these systems. The required Jacobians can be obtained elegantly with automatic differentiation (AD) [Griewank & Walther (2008)], a source code transformation providing exact derivatives. We compare the performance of the different iterative methods with their respective preconditioners for these linear systems. Furthermore, we analyze linear systems obtained by approximating the Jacobian with finite differences in terms of Newton steps per time step, steps of the iterative solvers and the overall solution time. Finally, we study the influence of heterogeneities in permeability and porosity on the performance of the iterative solvers and their robustness in this respect. References [Griewank & Walther(2008)] Griewank, A. & Walther, A., 2008. Evaluating Derivatives: Principles and Techniques of Algorithmic Differentiation, SIAM, Philadelphia, PA, 2nd edn. [Huber & Helmig(2000)] Huber, R. & Helmig, R., 2000. Node-centered finite volume discretizations for the numerical simulation of multiphase flow in heterogeneous porous media, Computational Geosciences, 4, 141-164. [Notay(2012)] Notay, Y., 2012. Aggregation-based algebraic multigrid for convection-diffusion equations, SIAM Journal on Scientific Computing, 34, A2288-A2316.
NASA Astrophysics Data System (ADS)
Lemieux, Jean-François; Tremblay, Bruno; Sedlá?ek, Jan; Tupper, Paul; Thomas, Stephen; Huard, David; Auclair, Jean-Pierre
2010-04-01
We have implemented the Jacobian-free Newton-Krylov (JFNK) method to solve the sea ice momentum equation with a viscous-plastic (VP) formulation. The JFNK method has many advantages: the system matrix (the Jacobian) does not need to be formed and stored, the method is parallelizable and the convergence can be nearly quadratic in the vicinity of the solution. The convergence rate of our JFNK implementation is characterized by two phases: an initial phase with slow convergence and a fast phase for which the residual norm decreases significantly from one Newton iteration to the next. Because of this fast phase, the computational gain of the JFNK method over the standard solver used in existing VP models increases with the required drop in the residual norm (termination criterion). The JFNK method is between 3 and 6.6 times faster (depending on the spatial resolution and termination criterion) than the standard solver using a preconditioned generalized minimum residual method. Resolutions tested in this study are 80, 40, 20 and 10 km. For a large required drop in the residual norm, both JFNK and standard solvers sometimes do not converge. The failure rate for both solvers increases as the grid is refined but stays relatively small (less than 2.3% of failures). With increasing spatial resolution, the velocity gradients (sea ice deformations) get more and more important. Nonlinear solvers such as the JFNK method tend to have difficulties when there are such sharp structures in the solution. This lack of robustness of both solvers is however a debatable problem as it mostly occurs for large required drops in the residual norm. Furthermore, when it occurs, it usually affects only a few grid cells, i.e., the residual is small for all the velocity components except in very localized regions. Globalization approaches for the JFNK solver, such as the line search method, have not yet proven to be successful. Further investigation is needed.
Armand Wirgin
2004-01-28
The inverse crime occurs when the same (or very nearly the same) theoretical ingredients are employed to synthesize as well as to invert data in an inverse problem. This act has been qualified as trivial and therefore to be avoided by Colton and Kress.
Jackiewicz, Jason [New Mexico State University, Department of Astronomy, P.O. Box 30001, Las Cruces, NM 88003 (United States)
2009-09-16
With the rapid advances in sophisticated solar modeling and the abundance of high-quality solar pulsation data, efficient and robust inversion techniques are crucial for seismic studies. We present some aspects of an efficient Fourier Optimally Localized Averaging (OLA) inversion method with an example applied to time-distance helioseismology.
NASA Astrophysics Data System (ADS)
Jackiewicz, Jason
2009-09-01
With the rapid advances in sophisticated solar modeling and the abundance of high-quality solar pulsation data, efficient and robust inversion techniques are crucial for seismic studies. We present some aspects of an efficient Fourier Optimally Localized Averaging (OLA) inversion method with an example applied to time-distance helioseismology.
Inverse Lighting for Photography
Donald P. Greenberg; Stephen R. Marschner
1997-01-01
We introduce a technique for improving photographs using inverse lighting, a new process based on algorithms developed in computer graphics for computing the reflection of light in 3D space. From a photograph and a 3D surface model for the object pictured, inverse lighting estimates the directional distribution of the incident light. We then use this information to process the photograph
ERIC Educational Resources Information Center
Bedard, Catherine; Belin, Pascal
2004-01-01
Voice is the carrier of speech but is also an ''auditory face'' rich in information on the speaker's identity and affective state. Three experiments explored the possibility of a ''voice inversion effect,'' by analogy to the classical ''face inversion effect,'' which could support the hypothesis of a voice-specific module. Experiment 1 consisted…
Kinematic Characterization of Left Ventricular Chamber Stiffness and Relaxation
NASA Astrophysics Data System (ADS)
Mossahebi, Sina
Heart failure is the most common cause of hospitalization today, and diastolic heart failure accounts for 40-50% of cases. Therefore, it is critical to identify diastolic dysfunction at a subclinical stage so that appropriate therapy can be administered before ventricular function is further, and perhaps irreversibly impaired. Basic concepts in physics such as kinematic modeling provide a unique method with which to characterize cardiovascular physiology, specifically diastolic function (DF). The advantage of an approach that is standard in physics, such as the kinematic modeling is its causal formulation that functions in contrast to correlative approaches traditionally utilized in the life sciences. Our research group has pioneered theoretical and experimental quantitative analysis of DF in humans, using both non-invasive (echocardiography, cardiac MRI) and invasive (simultaneous catheterization-echocardiography) methods. Our group developed and validated the Parametrized Diastolic Filling (PDF) formalism which is motivated by basic physiologic principles (LV is a mechanical suction pump at the mitral valve opening) that obey Newton's Laws. PDF formalism is a kinematic model of filling employing an equation of motion, the solution of which accurately predicts all E-wave contours in accordance with the rules of damped harmonic oscillatory motion. The equation's lumped parameters---ventricular stiffness, ventricular viscoelasticity/relaxation and ventricular load---are obtained by solving the 'inverse problem'. The parameters' physiologic significance and clinical utility have been repeatedly demonstrated in multiple clinical settings. In this work we apply our kinematic modeling approach to better understand how the heart works as it fills in order to advance the relationship between physiology and mathematical modeling. Through the use of this modeling, we thereby define and validate novel, causal indexes of diastolic function such as early rapid filling energy, diastatic stiffness, and relaxation and stiffness components of E-wave deceleration time.
Pearson, Bruce R. [Physics Department, Eindhoven University of Technology, Postbus 513, 5600 MB Eindhoven (Netherlands); School of Mechanical, Materials and Manufacturing Engineering, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Water, Willem van de [Physics Department, Eindhoven University of Technology, Postbus 513, 5600 MB Eindhoven (Netherlands)
2005-03-01
While the ordinary structure function in turbulence is concerned with the statistical moments of the velocity increment {delta}u measured over a distance r, the inverse structure function is related to the distance r where the turbulent velocity exits the interval {delta}u. We study inverse structure functions of wind-tunnel turbulence which covers a range of Reynolds numbers Re{sub {lambda}}=400-1100. We test a recently proposed relation between the scaling exponents of the ordinary structure functions and those of the inverse structure functions [S. Roux and M. H. Jensen, Phys. Rev. E 69, 16309 (2004)]. The relatively large range of Reynolds numbers in our experiment also enables us to address the scaling with Reynolds number that is expected to highlight the intermediate dissipative range. While we firmly establish the (relative) scaling of inverse structure functions, our experimental results fail both predictions. Therefore, the question of the significance of inverse structure functions remains open.
Kinematic Fitting of Detached Vertices
Paul Mattione
2007-05-01
The eg3 experiment at the Jefferson Lab CLAS detector aims to determine the existence of the $\\Xi_{5}$ pentaquarks and investigate the excited $\\Xi$ states. Specifically, the exotic $\\Xi_{5}^{--}$ pentaquark will be sought by first reconstructing the $\\Xi^{-}$ particle through its weak decays, $\\Xi^{-}\\to\\pi^{-}\\Lambda$ and $\\Lambda\\to\\pi^{-}$. A kinematic fitting routine was developed to reconstruct the detached vertices of these decays, where confidence level cuts on the fits are used to remove background events. Prior to fitting these decays, the exclusive reaction $\\gamma D\\rightarrow pp\\pi^{-}$ was studied in order to correct the track measurements and covariance matrices of the charged particles. The $\\Lambda\\rightarrow p\\pi^{-}$ and $\\Xi^{-}\\to\\pi^{-}\\Lambda$ decays were then investigated to demonstrate that the kinematic fitting routine reconstructs the decaying particles and their detached vertices correctly.
Science of NHL Hockey: Kinematics
NSDL National Science Digital Library
NBC Learn
2010-10-07
NHL skaters can reach speeds in excess of 20 miles (32km) per hour, and during some short bursts approach 30 miles (48 km) per hour. Kinematics, the branch of classical mechanics, helps describe a player's movement across the ice by defining his position, velocity and acceleration. "Science of NHL Hockey" is a 10-part video series produced in partnership with the National Science Foundation and the National Hockey League.
Non-universal relativistic kinematics
J. M. Carmona; J. L. Cortes; B. Romeo
2014-12-19
We present a systematic derivation of the constraints that the relativity principle imposes between coefficients of a deformed (but rotational invariant) momentum composition law, dispersion relation, and momentum transformation laws, at first order in a power expansion of an ultraviolet energy scale. This work generalizes previous results to the case of particle-dependent relativistic kinematics, which can have interesting phenomenological applications that we explore in the second part of the manuscript.
Of cilium and flagellum kinematics
NASA Astrophysics Data System (ADS)
Bandyopadhyay, Promode R.; Hansen, Joshua C.
2009-11-01
The kinematics of propulsion of small animals such as paramecium and spermatozoa is considered. Larger scale models of the cilium and flagellum have been built and a four-motor apparatus has been constructed to reproduce their known periodic motions. The cilium model has transverse deformational ability in one plane only, while the flagellum model has such ability in two planes. When the flagellum model is given a push-pull in one diametral plane, instead of transverse deflection in one plane, it forms a coil. Berg & Anderson's postulation (Nature 245 1973) that a flagellum rotates, is recalled. The kinematics of cilia of paramecium, of the whipping motion of the spermatozoa flagella, and of the flapping motion (rolling and pitching) of the pectoral fins of much larger animals such penguins, have been reproduced in the same basic paramecium apparatus. The results suggest that each of the tiny individual paramecium propulsors have the intrinsic dormant kinematic and structural building blocks to optimize into higher Reynolds number propulsors. A synthetic hypothesis on how small might have become large is animated.
"Nonrelativistic" kinematics: Particles or waves?
Jens Madsen Houlrik; Germain Rousseaux
2010-05-11
The kinematics of particles refer to events and tangent vectors, while that of waves refer to dual gradient planes. Special relativity [1-3] applies to both objects alike. Here we show that spacetime exchange symmetry [7] implicit in the SIdefinition of length based on the universal constant c has profound consequences at low velocities. Galilean physics, exact in the limit c \\to \\infty, is mirrored by a dual so-called Carrollian superluminal kinematics [4-6] exact in the limit c \\to 0. Several new results follow. The Galilean limit explains mass conservation in Newtonian mechanics, while the dual limit is a kinematical prerequisite for wavelike tachyonic motion [8, 9]. As an example, the Land\\'e paradox [19, 20] of waveparticle duality has a natural resolution within special relativity in terms of superluminal, particlelike waves. It is emphasized that internal particle energy mc^2 can not be ignored, while kinetic energy leads to an extended Galilei group. We also demonstrate that Maxwell's equations have magnetic and electric limits covariant under Galilean and Carrollian symmetry.
Plasma inverse transition acceleration
Xie, Ming
2001-06-18
It can be proved fundamentally from the reciprocity theorem with which the electromagnetism is endowed that corresponding to each spontaneous process of radiation by a charged particle there is an inverse process which defines a unique acceleration mechanism, from Cherenkov radiation to inverse Cherenkov acceleration (ICA) [1], from Smith-Purcell radiation to inverse Smith-Purcell acceleration (ISPA) [2], and from undulator radiation to inverse undulator acceleration (IUA) [3]. There is no exception. Yet, for nearly 30 years after each of the aforementioned inverse processes has been clarified for laser acceleration, inverse transition acceleration (ITA), despite speculation [4], has remained the least understood, and above all, no practical implementation of ITA has been found, until now. Unlike all its counterparts in which phase synchronism is established one way or the other such that a particle can continuously gain energy from an acceleration wave, the ITA to be discussed here, termed plasma inverse transition acceleration (PITA), operates under fundamentally different principle. As a result, the discovery of PITA has been delayed for decades, waiting for a conceptual breakthrough in accelerator physics: the principle of alternating gradient acceleration [5, 6, 7, 8, 9, 10]. In fact, PITA was invented [7, 8] as one of several realizations of the new principle.
NASA Astrophysics Data System (ADS)
Lee, J.; Kitanidis, P. K.
2014-07-01
The stochastic geostatistical inversion approach is widely used in subsurface inverse problems to estimate unknown parameter fields and corresponding uncertainty from noisy observations. However, the approach requires a large number of forward model runs to determine the Jacobian or sensitivity matrix, thus the computational and storage costs become prohibitive when the number of unknowns, m, and the number of observations, n increase. To overcome this challenge in large-scale geostatistical inversion, the Principal Component Geostatistical Approach (PCGA) has recently been developed as a "matrix-free" geostatistical inversion strategy that avoids the direct evaluation of the Jacobian matrix through the principal components (low-rank approximation) of the prior covariance and the drift matrix with a finite difference approximation. As a result, the proposed method requires about K runs of the forward problem in each iteration independently of m and n, where K is the number of principal components and can be much less than m and n for large-scale inverse problems. Furthermore, the PCGA is easily adaptable to different forward simulation models and various data types for which the adjoint-state method may not be implemented suitably. In this paper, we apply the PCGA to representative subsurface inverse problems to illustrate its efficiency and scalability. The low-rank approximation of the large-dimensional dense prior covariance matrix is computed through a randomized eigen decomposition. A hydraulic tomography problem in which the number of observations is typically large is investigated first to validate the accuracy of the PCGA compared with the conventional geostatistical approach. Then the method is applied to a large-scale hydraulic tomography with 3 million unknowns and it is shown that underlying subsurface structures are characterized successfully through an inversion that involves an affordable number of forward simulation runs. Lastly, we present a joint inversion of head and tracer test data using MODFLOW and MT3DMS as coupled black-box forward simulation solvers. These applications demonstrate the advantages of the PCGA, i.e., the scalability to high-dimensional inverse problems and the ability to utilize multiple forward models as black boxes.
NASA Astrophysics Data System (ADS)
Baasch, B.; Müller, H.; Oberle, F. K. J.; Dobeneck, T. von
2014-01-01
Electromagnetic induction (EMI) methods are widely used on land to map electric conductivity and/or magnetic susceptibility distributions of surficial sediments. In contrast, the application of these methods in marine environments is relatively novel. Based on the recently developed electromagnetic benthic profiler MARUM-NERIDIS III we investigate the potential of concentric-loop EMI methods to recover conductivity and susceptibility of layered marine sediments. Sensitivity analyses based on a data and model normalized Jacobian matrix were performed to compare the influence of conductivity and susceptibility to in-phase and quadrature components at different frequencies. Both parameters substantially affect the EM response. However, the influence of susceptibility decreases more with depth and offers lower depth resolution than that of conductivity. A 1-D inversion algorithm to reconstruct vertical conductivity distributions was developed from existing non-linear inversion methods using apparent conductivity and apparent susceptibility recovered from simultaneous half-space inversion as a priori information. This algorithm was tested on synthetic and real marine EM data from a commercial multifrequency concentric loop EMI system (GEM-3). The results indicate that our inversion algorithm yields meaningful results down to approximately 3 m depth under typical shallow marine conditions. The comparison of inversion results recovered with 1-D and 2-D constraints showed that combining lateral with vertical constraints substantially improves the resolution of the inversion outputs. Field data from the NW Iberian shelf was calibrated according to a processing flow specifically designed for underwater conditions and analysed. Inversion outputs are in good agreement with ground-truthing stratigraphic investigations and deliver relevant clues on past and present sediment dynamics.
Kalb, J.
1992-05-01
This paper describes the design of an inverse adaptive filter, using the Least-Mean-Square (LMS) algorithm, the correct data taken with an analog filter. The gradient estimate used in the LMS algorithm is based upon the instantaneous error, e{sup 2}(n). Minimizing the mean-squared-error does not provide an optimal solution in this specific case. Therefore, another performance criterion, error power, was developed to calculate the optimal inverse model. Despite using a different performance criterion, the inverse filter converges rapidly and gives a small mean-squared-error. Computer simulations of this filter are also shown in this paper.
Goal driven kinematic simulation of flexible arm robot for space station missions
NASA Technical Reports Server (NTRS)
Janssen, P.; Choudry, A.
1987-01-01
Flexible arms offer a great degree of flexibility in maneuvering in the space environment. The problem of transporting an astronaut for extra-vehicular activity using a space station based flexible arm robot was studied. Inverse kinematic solutions of the multilink structure were developed. The technique is goal driven and can support decision making for configuration selection as required for stability and obstacle avoidance. Details of this technique and results are given.
The Maximal Kinematical Invariance Group of Fluid Dynamics and Explosion–Implosion Duality
L. O'Raifeartaigh; V. V. Sreedhar
2001-01-01
It has recently been found that supernova explosions can be simulated in the laboratory by implosions induced in a plasma by intense lasers. A theoretical explanation is that the inversion transformation, (?:t??1\\/t, x?x\\/t), leaves the Euler equations of fluid dynamics, with standard polytropic exponent, invariant. This implies that the kinematical invariance group of the Euler equations is larger than the
NASA Astrophysics Data System (ADS)
Lu, Qipeng; Li, Yongjun; Peng, Zhongqi
2012-05-01
Six-bar parallel mechanism is now widely applied in synchrotron radiation beamline, while the six-dimensional adjustment is difficult and inefficient for lack of theoretical direction. This paper introduces a special six-bar parallel mechanism. By means of coordinate transformations, the inverse kinematics of six-bar parallel mechanism is studied, and the precise equations for six bars' lengths are obtained. Based on the inverse kinematics, forward kinematics of six-bar parallel mechanism is obtained with trust region method working for nonlinear optimization. The corresponding MATLAB program is also designed. The results show that trust region method is an effective way to solve forward kinematics, and the program is stable, reliable and rapid. This method has small errors with linear precision of 10-12 mm and rotational precision of 10-15 deg. Using differential snail adjustment, monochromator chamber's attitude can reach a linear resolution of 5 ?m and a rotational resolution of 3?, which entirely satisfies the practical requirements.
Inverse scattering connections
Leon, J.J.
1981-05-01
We establish and study a transformation which connects the Schroedinger, the Klein-Gordon, and the Dirac operators. This provides an equivalence between their associated direct and inverse spectral transforms.
Geological Inverse Theory Resources
NSDL National Science Digital Library
Ganse, Andrew A.
This website from Andrew A. Ganse of the University of Washington's Applied Physics Laboratory includes a list of resources on geophysical inverse theory. It includes introductory material, textbooks, papers, web resources, lab lecture notes and more.
Wang, Fang
2014-06-26
inverse problem to optimization problems of minimizing the norm of the data misfit plus a weighted regularization functional that incorporates the a priori information we may have about the original problem. The choices of the regularization functional r(q...
Kinematic correction for roller skewing
NASA Technical Reports Server (NTRS)
Savage, M.; Loewenthal, S. H.
1980-01-01
A theory of kinematic stabilization of rolling cylinders is developed for high-speed cylindrical roller bearings. This stabilization requires race and roller crowning to product changes in the rolling geometry as the roller shifts axially. These changes put a reverse skew in the rolling elements by changing the rolling taper. Twelve basic possible bearing modifications are identified in this paper. Four have single transverse convex curvature in the rollers while eight have rollers with compound transverse curvature composed of a central cylindrical band of constant radius surrounded by symmetric bands with both slope and transverse curvature.
Kinematics in Vector Boson Fusion
D. Green
2006-03-02
The vector boson fusion process leads to two forward/backward jets (tag jets) and the produced state, a Higgs boson in this case, moving slowly in the p-p C.M. frame at the LHC. For the case of Higgs decaying to W+W (W*) with Higgs mass below 180 GeV, the W bosons have low momentum in the Higgs C.M. For the case of W leptonic decays, this fact allows for an approximate reconstruction of the two final state neutrinos. In turn, those solutions then provide additional kinematic cuts against background.
NASA Astrophysics Data System (ADS)
Angermann, D.; Drewes, H.
The ongoing expansion of space-geodetic techniques in the last years lead to continuous improvements for the definition and realization of the Conventional Terrestrial System (CTS). The latest and most precise realization of the CTS is the International Terrestrial Reference Frame 1997. Furthermore the space-geodetic data provide an excellent basis for measuring global plate motions over a time scale of years. Based on global VLBI-, SLR- and GPS solutions, DGFI computed and Actual Plate KInematic Model (APKIM). The APKIM results were compared with the geological-geophysical plate motion model NNR NUVEL-1A.
Karaoulis, M.; Revil, A.; Werkema, D.D.; Minsley, B.J.; Woodruff, W.F.; Kemna, A.
2011-01-01
Induced polarization (more precisely the magnitude and phase of impedance of the subsurface) is measured using a network of electrodes located at the ground surface or in boreholes. This method yields important information related to the distribution of permeability and contaminants in the shallow subsurface. We propose a new time-lapse 3-D modelling and inversion algorithm to image the evolution of complex conductivity over time. We discretize the subsurface using hexahedron cells. Each cell is assigned a complex resistivity or conductivity value. Using the finite-element approach, we model the in-phase and out-of-phase (quadrature) electrical potentials on the 3-D grid, which are then transformed into apparent complex resistivity. Inhomogeneous Dirichlet boundary conditions are used at the boundary of the domain. The calculation of the Jacobian matrix is based on the principles of reciprocity. The goal of time-lapse inversion is to determine the change in the complex resistivity of each cell of the spatial grid as a function of time. Each model along the time axis is called a 'reference space model'. This approach can be simplified into an inverse problem looking for the optimum of several reference space models using the approximation that the material properties vary linearly in time between two subsequent reference models. Regularizations in both space domain and time domain reduce inversion artefacts and improve the stability of the inversion problem. In addition, the use of the time-lapse equations allows the simultaneous inversion of data obtained at different times in just one inversion step (4-D inversion). The advantages of this new inversion algorithm are demonstrated on synthetic time-lapse data resulting from the simulation of a salt tracer test in a heterogeneous random material described by an anisotropic semi-variogram. ?? 2011 The Authors Geophysical Journal International ?? 2011 RAS.
Kinematically Decoupled Cores in Dwarf (Elliptical) Galaxies
NASA Astrophysics Data System (ADS)
Toloba, E.; Peletier, R. F.; Guhathakurta, P.; van de Ven, G.; Boissier, S.; Boselli, A.; Brok, M. d.; Falcón-Barroso, J.; Hensler, G.; Janz, J.; Laurikainen, E.; Lisker, T.; Paudel, S.; Ry?, A.; Salo, H.
2014-05-01
An overview is given of what we know about the frequency of kinematically decoupled cores in dwarf elliptical galaxies. New observations show that kinematically decoupled cores happen just as often in dwarf elliptical as in ordinary early-type galaxies. This has important consequences for the formation of kinematically decoupled cores. Our currently most popular theory for kinematically decoupled cores in dwarf ellipticals is that they were formed in a poor group environment or in isolation, and subsequent fell into the cluster environment where star formation was quenched.
Augmented haptics of manipulator kinematic condition
NASA Astrophysics Data System (ADS)
Maneewarn, Thavida; Hannaford, Blake
1999-11-01
This paper describes a study of whether haptic feedback can be used to represent information that is normally difficult to obtain via visual feedback in telerobotic system. Problems of manipulator kinematic condition such as singularity and joint limit have been well known for a long time. Kinematic condition of the manipulator is difficult to be recognized visually. Poor kinematic condition often causes trajectory error or other undesirable effects in the system. This problem is quite significant in telerobotics since a fully pre-planned path that completely excludes poor kinematic condition is usually not available.
Basic concepts of kinematic-wave models
Miller, J.E.
1984-01-01
The kinematic-wave model is one of a number of approximations of the dynamic-wave model. The dynamic-wave model describes one-dimensional shallow-water waves (unsteady, gradually varied, open-channel flow). The report provides a basic reference on the theory and application of kinematic-wave models and describes the limitations of the model in relation to the other approximations of the dynamic-wave model. In the kinematic-wave approximation, a number of the terms in the equation of motion are assumed to be insignificant. The equation of motion is replaced by an equation describing uniform flow. Thus, the kinematic-wave model is described by the continuity equation and a uniform flow equation such as the well-known Chezy or Manning formulas. Kinematic-wave models are applicable to overland flow where lateral inflow is continuously added and is a large part of the total flow. For channel-routing applications, the kinematic-wave model always predicts a steeper wave with less dispersion and attenuation than actually occurs. The effect of the accumulation of errors in the kinematic-wave model shows that the approximations made in the development of the kinematic-wave equations are not generally justified for most channel-routing applications. Modified flow-routing models can be used which help to stop the accumulation of error that occurs when the kinematic-wave model is applied. (USGS)
Hart, K.A.
1994-01-01
During the Intensive Observation Period (IOP), several periods of water vapor and temperature inversions near the 0 deg C level were observed. Satellite and radiosonde data from TOGA COARE are used to document the large-scale conditions and thermodynamic and kinematic structures present during three extended periods in which moisture and temperature inversions near the freezing level were very pronounced. Observations from each case are synthesized into schematics which represent typical structures of the inversion phenomena. Frequency distributions of the inversion phenomena along with climatological humidity and temperature profiles are calculated for the four-month IOP.
Erik Bernsen; Henk A. Dijkstra; Jonas Thies; Fred W. Wubs
2010-01-01
In present-day forward time stepping ocean-climate models, capturing both the wind-driven and thermohaline components, a substantial amount of CPU time is needed in a so-called spin-up simulation to determine an equilibrium solution. In this paper, we present methodology based on Jacobian-Free Newton–Krylov methods to reduce the computational time for such a spin-up problem. We apply the method to an idealized
Erik Bernsen; Henk A. Dijkstra; Jonas Thies; Fred W. Wubs
2010-01-01
In present-day forward time stepping ocean-climate models, capturing both the wind-driven and thermohaline components, a substantial amount of CPU time is needed in a so-called spin-up simulation to determine an equilibrium solution. In this paper, we present methodology based on Jacobian-Free Newton-Krylov methods to reduce the computational time for such a spin-up problem. We apply the method to an idealized
Robert Nourgaliev; Dana Knoll
2007-01-01
The Discontinuous Galerkin (DG) method for compressible fluid flows is incorporated into the Jacobian-Free Newton-Krylov (JFNK) framework. Advantages of combining the DG with the JFNK are two-fold: a) enabling robust and efficient high-order-accurate modeling of all-speed flows on unstructured grids, opening the possibility for high-fidelity simulation of nuclear-power-industry-relevant flows; and b) ability to tightly, robustly and high-order-accurately couple with other
Ballistic representation for kinematic access
NASA Astrophysics Data System (ADS)
Alfano, Salvatore
2011-01-01
This work uses simple two-body orbital dynamics to initially determine the kinematic access for a ballistic vehicle. Primarily this analysis was developed to assess when a rocket body might conjunct with an orbiting satellite platform. A family of access opportunities can be represented as a volume for a specific rocket relative to its launch platform. Alternately, the opportunities can be represented as a geographical footprint relative to aircraft or satellite position that encompasses all possible launcher locations for a specific rocket. A thrusting rocket is treated as a ballistic vehicle that receives all its energy at launch and follows a coasting trajectory. To do so, the rocket's burnout energy is used to find its equivalent initial velocity for a given launcher's altitude. Three kinematic access solutions are then found that account for spherical Earth rotation. One solution finds the maximum range for an ascent-only trajectory while another solution accommodates a descending trajectory. In addition, the ascent engagement for the descending trajectory is used to depict a rapid access scenario. These preliminary solutions are formulated to address ground-, sea-, or air-launched vehicles.
Baes, Maarten
q 2000 RAS Kinematics of elliptical galaxies with a diffuse dust component ± II. Dust effects on kinematic modelling Maarten Baes,w ² Herwig Dejonghe and Sven De Rijcke² Sterrenkundig Observatorium, and affects the projection of each physical (and kinematic) quantity. In a previous paper, we have
Hull, Maury
technique such as kinematically aligned total knee arthroplasty (TKA). Edge loading of the tibial liner kneeling with kinematically aligned TKA are minimal and not different between groups of con- secutive, kinematically aligned TKA with patient-specific guides in a consecutive series of patients with their pre
Robust adaptive kinematic control of redundant robots
NASA Technical Reports Server (NTRS)
Tarokh, M.; Zuck, D. D.
1992-01-01
The paper presents a general method for the resolution of redundancy that combines the Jacobian pseudoinverse and augmentation approaches. A direct adaptive control scheme is developed to generate joint angle trajectories for achieving desired end-effector motion as well as additional user defined tasks. The scheme ensures arbitrarily small errors between the desired and the actual motion of the manipulator. Explicit bounds on the errors are established that are directly related to the mismatch between actual and estimated pseudoinverse Jacobian matrix, motion velocity and the controller gain. It is shown that the scheme is tolerant of the mismatch and consequently only infrequent pseudoinverse computations are needed during a typical robot motion. As a result, the scheme is computationally fast, and can be implemented for real-time control of redundant robots. A method is incorporated to cope with the robot singularities allowing the manipulator to get very close or even pass through a singularity while maintaining a good tracking performance and acceptable joint velocities. Computer simulations and experimental results are provided in support of the theoretical developments.
Non-linear traveltime inversion for 3-D seismic tomography in strongly anisotropic media
NASA Astrophysics Data System (ADS)
Zhou, Bing; Greenhalgh, Stewart
2008-01-01
We have developed two, new non-linear traveltime inversion schemes for 3-D seismic tomography in anisotropic media. They differ from the traditional linearized inversion approach and offer five significant improvements: (1) they are based on an alternative form of the first-order traveltime perturbation equation, derived so as to simplify the inversion formulae and overcome the quasi shear wave singularity problem; (2) robust 3-D ray tracing is employed which enables the simultaneous computation of the first-arrival traveltimes and ray paths for the three body waves (qP, qS1 and qS2) in arbitrary anisotropic media; (3) the Jacobian matrix used in the update is based on an efficient computation for a 3-D anisotropic model, so that the inversion is applicable to both weakly and strongly anisotropic situations, unlike most previous approaches which assume weak anisotropy; (4) a local-search, constrained minimization is applied to the non-linear inversion which makes anisotropic tomographic imaging an iterative procedure; (5) there is an option to invert for the elastic moduli directly or the Thomsen parameters directly in heterogenous, tilted transversely isotropic media, using any source-receiver recording geometry. We have examined the imaging capability of the non-linear solver with individual body-wave modes using a 3-D synthetic anisotropic model incorporating two targets, a `high velocity' and a `low velocity' anomaly, embedded in a titled transversely isotropic medium. The model is illuminated by means of azimuthal VSP and crosshole measurements. The experimental results show that the two non-linear inversion schemes successfully image the `targets' and yield satisfactory 3-D tomograms of the elastic moduli and the Thomsen parameters.
NASA Astrophysics Data System (ADS)
Lemieux, Jean-François; Price, Stephen F.; Evans, Katherine J.; Knoll, Dana; Salinger, Andrew G.; Holland, David M.; Payne, Antony J.
2011-07-01
We have implemented the Jacobian-free Newton-Krylov (JFNK) method for solving the first-order ice sheet momentum equation in order to improve the numerical performance of the Glimmer-Community Ice Sheet Model (Glimmer-CISM), the land ice component of the Community Earth System Model (CESM). Our JFNK implementation is based on significant re-use of existing code. For example, our physics-based preconditioner uses the original Picard linear solver in Glimmer-CISM. For several test cases spanning a range of geometries and boundary conditions, our JFNK implementation is 1.8-3.6 times more efficient than the standard Picard solver in Glimmer-CISM. Importantly, this computational gain of JFNK over the Picard solver increases when refining the grid. Global convergence of the JFNK solver has been significantly improved by rescaling the equation for the basal boundary condition and through the use of an inexact Newton method. While a diverse set of test cases show that our JFNK implementation is usually robust, for some problems it may fail to converge with increasing resolution (as does the Picard solver). Globalization through parameter continuation did not remedy this problem and future work to improve robustness will explore a combination of Picard and JFNK and the use of homotopy methods.
A parallel Jacobian-free Newton-Krylov solver for a coupled sea ice-ocean model
NASA Astrophysics Data System (ADS)
Losch, Martin; Fuchs, Annika; Lemieux, Jean-François; Vanselow, Anna
2014-01-01
The most common representation of sea ice dynamics in climate models assumes that sea ice is a quasi-continuous non-normal fluid with a viscous-plastic rheology. This rheology leads to non-linear sea ice momentum equations that are notoriously difficult to solve. Recently a Jacobian-free Newton-Krylov (JFNK) solver was shown to solve the equations accurately at moderate costs. This solver is extended for massive parallel architectures and vector computers and implemented in a coupled sea ice-ocean general circulation model for climate studies. Numerical performance is discussed along with numerical difficulties in realistic applications with up to 1920 CPUs. The parallel JFNK-solver's scalability competes with traditional solvers although the collective communication overhead starts to show a little earlier. When accuracy of the solution is required (i.e. reduction of the residual norm of the momentum equations of more that one or two orders of magnitude) the JFNK-solver is unrivalled in efficiency. The new implementation opens up the opportunity to explore physical mechanisms in the context of large scale sea ice models and climate models and to clearly differentiate these physical effects from numerical artifacts.
Inter-segment foot kinematics during cross-slope running.
Dixon, Philippe C; Tisseyre, Magali; Damavandi, Mohsen; Pearsall, David J
2011-04-01
Cross-slopes are a common terrain characteristic, however there is no biomechanical knowledge of the intra-foot adaptations required for running on these surface inclinations. The purpose of this study was to evaluate the kinematic changes induced within the foot while running on a transversely inclined surface. A three-segment foot model distinguishing between the hindfoot, forefoot, and hallux was used for this purpose. Nine healthy experienced male runners volunteered to perform level (0°) and cross-slope (10°) running trials barefoot at a moderate speed. Multivariate analysis of variance (MANOVA) for repeated measures was used to analyze the kinematics of the hindfoot with respect to tibia (HF/TB), forefoot with respect to hindfoot (FF/HF), and hallux with respect to forefoot (HX/FF) during level running (LR), incline running up-slope (IRU), and incline running down-slope (IRD) conditions. In the sagittal plane, the FF/HF angle showed greater dorsiflexion at peak vertical force production (MaxFz) in IRD compared to LR (p=0.042). The HX/FF was significantly more extended during IRU than LR at foot strike (p=0.027). More importantly, frontal plane asymmetries were also found. HF/TB angles revealed greater inversion at foot strike followed by greater eversion at MaxFz for IRU compared to IRD (p=0.042 and p=0.018, respectively). For the FF/HF angle, maximum eversion was greater during IRD than LR (p=0.035). Data suggests that running on cross-slopes can induce substantial intra-foot kinematic adaptations, whether this represents a risk of injury to both recreational and professional runners remains to be determined. PMID:21420865
Pant-tilt Platform Design Based on Parallel Kinematics
NASA Astrophysics Data System (ADS)
Majarena, A. C.; Santolaria, J.; Aguilar, J. J.; Pastor, J.; Cajal, Cajal
2009-11-01
A new long distance measurement system design, based on parallel kinematics, is presented in this paper. This system has two degrees of freedom for positioning and orientating two high precision cameras. In this document is presented the system design. Several configurations have been analyzed and the components needed such as actuators, linear captators (to measure the displacement), spherical ball-and-socket joints and universal joints, have been selected. The developed model allows us to obtain the kinematic joint variables, depending on geometric parameters, by means of the resolution of opened chains for each leg. The direct model allows us to obtain the platform position and orientation for a determined displacement values. Once the matrix transformation (which describes the coordinates of the platform reference system respect to the base reference system) is obtained, the actuators elongation can be found out through the inverse model with numeric or geometric methods. The design optimization, by means of the analysis of anchorage points and the study of singularities (analysis of the limited platform positions, depending on maximum strut lengths and maximum angle that joints can turn), allows us to optimize the workspace of the platform.
Multiple diffraction in the kinematical approach.
Rossmanith, Elisabeth
2006-05-01
The expressions derived for the calculation of multiple diffraction patterns for a perfect crystal in the framework of the kinematical theory are compared with the relevant result of the kinematical power-transfer equation deduced for a mosaic crystal. It is shown that the results of the two concepts differ appreciably. PMID:16614489
Local stellar kinematics from HIPPARCOS data
Walter Dehnen; James J. Binney
1998-01-01
From the parallaxes and proper motions of a kinematically unbiased subsample of the Hipparcos Catalogue, we have re-determined as a function of colour the kinematics of main-sequence stars. Whereas the radial and vertical components of the mean heliocentric velocity of stars show no trend with colour, the component in the direction of Galactic rotation nicely follows the asymmetric drift relation,
Wheeled Mobile Robots Introduction and Kinematic Modeling
De Luca, Alessandro
Robotics 1 Wheeled Mobile Robots Introduction and Kinematic Modeling Prof. Alessandro De Luca Robotics 1 1 #12;Summary introduction Wheeled Mobile Robot (WMR) operating environments basic motion problem elementary tasks block diagram of a mobile robot kinematic modeling configuration space wheel
Programming and control of kinematically redundant manipulators
John Baillieul; John Hollerbach; Roger Brockett
1984-01-01
Because kinematically redundant robot manipulators have extra degrees of freedom with which to move and orient end effectors in the workspace, they offer a number of advantages over nonredundant designs. In this paper we show how extra degrees of freedom may be used to mitigate the problem of kinematically singular configurations. Programming and control techniques for resolution of redundancy are
Quark-gluon vertex in general kinematics
Ayse Kizilersu; Derek B. Leinweber; Jon-Ivar Skullerud; Anthony G. Williams
2007-03-07
We compute the quark-gluon vertex in quenched lattice QCD, in the Landau gauge using an off-shell mean-field O(a)-improved fermion action. The Dirac-vector part of the vertex is computed for arbitrary kinematics. We find a substantial infrared enhancement of the interaction strength regardless of the kinematics.
Prof. Alessandro De Luca Kinematic calibration
De Luca, Alessandro
#12;Cartesian measurement systems - 1 calibration table Robotics 2 4 #12;Cartesian measurement systems - 2 laser/camera system + triangulation Robotics 2 5 #12;Cartesian measurement systems - 3 laserRobotics 2 Prof. Alessandro De Luca Kinematic calibration #12;Direct kinematics ! nominal set
Can a pseudo-dynamic source inversion approach improve earthquake source imaging?
NASA Astrophysics Data System (ADS)
Zhang, Youbing; Song, Seok Goo; Dalguer, Luis; Clinton, John
2014-05-01
Imaging a high resolution spatio-temporal slip distribution of an earthquake rupture is a core research goal in seismology. In general we expect to obtain a higher quality source image by improving the observational input data (e.g. using more, higher quality, near field stations). However, recent studies show that increasing the surface station density alone does not significantly improve source inversion results (Custodio et al. 2005; Zhang et al. in review). Song et al. (2009) and Song and Dalguer (2013) found interesting correlation structures between kinematic source parameters (e.g. slip, peak slip velocity and rupture velocity) obtained both from kinematic inversion and dynamic modeling. These correlation structures that effectively regularize the model space may improve source imaging more than by simply improving the observational data. In this 'pseudo-dynamic' source inversion, source images are constrained by both physical constraints derived from rupture dynamics as well all the observational data, without compromising the computational efficiency of kinematic inversion. We investigate the efficiency of the pseudo-dynamic source inversion using synthetic dynamic rupture models. Our target model is a buried vertical strike-slip event (Mw 7.3) in a homogeneous half space. In the inversion, we model low frequency (below 1Hz) waveforms using a genetic algorithm in a Bayesian framework (Moneli et al. 2008). A dynamically consistent regularized Yoffe function (Tinti, et al. 2005) was applied as a single-window slip velocity function. We have first implemented the autocorrelation of slip in the prior distribution in the Bayesian inversion - preliminary results show that estimated kinematic source models closely match the target dynamic model. The prior information describing the auto-correlation of source parameters (e.g. slip) improves the imaging of spatial distribution of source parameters. By implementing both auto- and cross-correlation of kinematic source parameters, we can regularize the model space in a more physics-based manner and improve the source imaging more significantly compared to using traditional smoothing constraints. Further investigation is needed to tune the related parameters of pseudo-dynamic source inversion and relative weighting between the prior and the likelihood function in the Bayesian inversion.
Kinematic model of southern California
Weldon, R.; Humphreys, E.
1986-02-01
A kinematic model for southern California, based on late-Quaternary slip rates and orientations of major faults in the region, is proposed. Internally consistent motions are determined assuming that these faults bound rigid blocks. Relative to North America, most of California west of the San Andreas fault is moving parallel to the San Andreas fault through the Transverse Ranges and not parallel to the motion of the Pacific plate. The velocities of the blocks are calculated along several paths in southern California that begin in the Mojave Desert and end off the California coast. A path that crosses the western Transverse Ranges accumulates the accepted relative North America-Pacific plate velocity, whereas paths to the north and south result in a significant missing component of motion, implying the existence of a zone of active deformation in southern California. 70 references.
Quantum trajectories from kinematic considerations
NASA Astrophysics Data System (ADS)
Coffey, T. M.; Wyatt, R. E.; Schieve, W. C.
2010-08-01
We present a method in which one can infer deterministic particle trajectories for quantum mechanics using just the time evolving probability density ? = ?*? and without assuming or solving any equations of motion. The approach utilizes the geometrical construction of centroidal Voronoi tessellations (CVT). In one dimension the CVT trajectories are shown to be identical to the particle trajectories of Bohm's quantum mechanics. Several two-dimensional numerical examples are given in which the resulting CVT trajectories are highly correlated with Bohm's trajectories. The method also allows the formation of trajectories for classical probability densities, for which the resulting trajectories are not, in general, the physically observed trajectories. Rather, they are hydrodynamic trajectories which kinematically depict the evolving density.
The Kinematics of Circular Motion
L. A. N. de Paula
2008-10-22
In this paper we introduce a proposal for the kinematics of bodies in uniform circular motion. This model could contribute for the explanation of the two main problems of contemporary cosmology: dark matter and dark energy. We use one of the physical properties of space - the gravitational waves - to define a reference frame at rest with respect to the space and to determine a mechanism for the synchronization of clocks. So we derive through a Postulate the so-called transformations of Lorentz and a new velocity of the bodies in uniform circular motion. This rotational velocity could contribute to clarify both cosmological problems. This contribution would come from effects due to a single phenomenon: the rotational velocity of bodies with respect to the reference frame at rest on the space. And finally, we interpret physically the Postulate - the major point in this model - which allows, inclusive, a comparison with the Relativity Principle and also new theoretical previews.
Automated kinematic generator for surgical robotic systems.
Jung, David L; Dixon, Warren E; Pin, François G
2004-01-01
Unlike traditional assembly line robotic systems that have a fixed kinematic structure associated with a single tool for a structured task, next-generation robotic surgical assist systems will be required to use an array of end-effector tools. Once a robot is connected with a tool, the kinematic equations of motion are altered. Given the need to accommodate evolving surgical challenges and to alleviate the restrictions imposed by the confined minimally invasive environment, new surgical tools may resemble small flexible snakes rather than rigid, cable driven instruments. Connecting to these developing articulated tools will significantly alter the overall kinematic structure of a robotic system. In this paper we present a technique for real-time automated generation and evaluation of manipulator kinematic equations that exhibits the combined advantages of existing methods-speed and flexibility to kinematic change--without their disadvantages. PMID:15544260
Off-shell Color-Kinematics Duality
Pierpaolo Mastrolia; Amedeo Primo; Ulrich Schubert; William J. Torres Bobadilla
2015-07-27
We elaborate on the color-kinematics duality for off-shell diagrams in gauge theories coupled to matter, by investigating the scattering process $gg\\to ss, q\\bar q, gg$, and show that the Jacobi relations for the kinematic numerators of off-shell diagrams, built with Feynman rules in axial gauge, reduces to a color-kinematics violating term due to the contributions of sub-graphs only. Such anomaly vanishes when the four particles connected by the Jacobi relation are on their mass shell with vanishing squared momenta, being either external or cut particles, where the validity of the color-kinematics duality is recovered. We discuss the role of this off-shell decomposition in the direct construction of higher-multiplicity numerators satisfying color-kinematics identity, providing an explicit example for the QCD process $gg\\to q\\bar{q}g$.
Off-shell Color-Kinematics Duality
Mastrolia, Pierpaolo; Schubert, Ulrich; Bobadilla, William J Torres
2015-01-01
We elaborate on the color-kinematics duality for off-shell diagrams in gauge theories coupled to matter, by investigating the scattering process $gg\\to ss, q\\bar q, gg$, and show that the Jacobi relations for the kinematic numerators of off-shell diagrams, built with Feynman rules in axial gauge, reduces to a color-kinematics violating term due to the contributions of sub-graphs only. Such anomaly vanishes when the four particles connected by the Jacobi relation are on their mass shell with vanishing squared momenta, being either external or cut particles, where the validity of the color-kinematics duality is recovered. We discuss the role of this off-shell decomposition in the direct construction of higher-multiplicity numerators satisfying color-kinematics identity, providing an explicit example for the QCD process $gg\\to q\\bar{q}g$.
Scapulothoracic and Glenohumeral Kinematics Following an External Rotation
Karduna, Andrew
Scapulothoracic and Glenohumeral Kinematics Following an External Rotation Fatigue Protocol D-dimensional scapulothoracic and glenohumeral kinematics. Background: The external rotator muscles leads to altered kinematics of the shoulder girdle. Methods and Measures: Twenty subjects without
Philosophy of Science Association Probability Kinematics and Commutativity
Wagner, Carl
Philosophy of Science Association Probability Kinematics and Commutativity Author(s): Carl G. Introduction.The much remarked "non-commutativity" of probability kinematics (Domotor 1982, Skyrms 1986, van identical posterior probabilities, then sequential probability-kinematical revisions behave just
Suprascapular nerve block disrupts the normal pattern of scapular kinematics
Karduna, Andrew
Suprascapular nerve block disrupts the normal pattern of scapular kinematics Sean P. Mc kinematics with a Polhemus magnetic tracking device and isometric force measurements during external rotation of each subject. Scapular kinematics and isometric force measurements were repeated after confirmation
Computer Analysis and Visualization of Kinematics and Dynamics Sensibility Parameters
Borissova, Daniela
3 7 Computer Analysis and Visualization of Kinematics and Dynamics Sensibility Parameters Daniela, especially on sensibility parameters coefficients and directions of kinematics [1, 2] and dynamics sensibility. The dynamics sensibility parameters are determined on the basis of the kinematics ones
Non-linear inverse scattering: High resolution quantitative breast tissue tomography
Wiskin, J.; Borup, D. T.; Johnson, S. A.; Berggren, M.
2012-01-01
Recent published results in inverse scattering generally show the difficulty in dealing with moderate to high contrast inhomogeneities when employing linearized or iteratively linearized algorithms (e.g., distorted Born iterative method). This paper presents a fully nonlinear algorithm utilizing full wave field data, that results in ultrasound computed tomographic images from a laboratory breast scanner, and shows several such unique images from volunteer subjects. The forward problem, data collection process and inverse scattering algorithm used are discussed. A functional that represents the “best fit” between predicted and measured data is minimized, and therefore requires a very fast forward problem solver, Jacobian calculation, and gradient estimation, all of which are described. The data collection device is described. The algorithm and device yield quantitative estimates of human breast tissue in vivo. Several high resolution images, measuring ?150 by 150 wavelengths, obtained from the 2D inverse scattering algorithms, using data collected from a first prototype, are shown and discussed. The quantitative values are compared with previous published work. PMID:22559356
Estimation of near-surface shear-wave velocity by inversion of Rayleigh waves
Xia, J.; Miller, R.D.; Park, C.B.
1999-01-01
The shear-wave (S-wave) velocity of near-surface materials (soil, rocks, pavement) and its effect on seismic-wave propagation are of fundamental interest in many groundwater, engineering, and environmental studies. Rayleigh-wave phase velocity of a layered-earth model is a function of frequency and four groups of earth properties: P-wave velocity, S-wave velocity, density, and thickness of layers. Analysis of the Jacobian matrix provides a measure of dispersion-curve sensitivity to earth properties. S-wave velocities are the dominant influence on a dispersion curve in a high-frequency range (>5 Hz) followed by layer thickness. An iterative solution technique to the weighted equation proved very effective in the high-frequency range when using the Levenberg-Marquardt and singular-value decomposition techniques. Convergence of the weighted solution is guaranteed through selection of the damping factor using the Levenberg-Marquardt method. Synthetic examples demonstrated calculation efficiency and stability of inverse procedures. We verify our method using borehole S-wave velocity measurements.Iterative solutions to the weighted equation by the Levenberg-Marquardt and singular-value decomposition techniques are derived to estimate near-surface shear-wave velocity. Synthetic and real examples demonstrate the calculation efficiency and stability of the inverse procedure. The inverse results of the real example are verified by borehole S-wave velocity measurements.
Knupp, P.M.
1999-03-26
Three-dimensional unstructured tetrahedral and hexahedral finite element mesh optimization is studied from a theoretical perspective and by computer experiments to determine what objective functions are most effective in attaining valid, high quality meshes. The approach uses matrices and matrix norms to extend the work in Part I to build suitable 3D objective functions. Because certain matrix norm identities which hold for 2 x 2 matrices do not hold for 3 x 3 matrices. significant differences arise between surface and volume mesh optimization objective functions. It is shown, for example, that the equivalence in two-dimensions of the Smoothness and Condition Number of the Jacobian matrix objective functions does not extend to three dimensions and further. that the equivalence of the Oddy and Condition Number of the Metric Tensor objective functions in two-dimensions also fails to extend to three-dimensions. Matrix norm identities are used to systematically construct dimensionally homogeneous groups of objective functions. The concept of an ideal minimizing matrix is introduced for both hexahedral and tetrahedral elements. Non-dimensional objective functions having barriers are emphasized as the most logical choice for mesh optimization. The performance of a number of objective functions in improving mesh quality was assessed on a suite of realistic test problems, focusing particularly on all-hexahedral ''whisker-weaved'' meshes. Performance is investigated on both structured and unstructured meshes and on both hexahedral and tetrahedral meshes. Although several objective functions are competitive, the condition number objective function is particularly attractive. The objective functions are closely related to mesh quality measures. To illustrate, it is shown that the condition number metric can be viewed as a new tetrahedral element quality measure.
White, John L.
1967-07-01
Very shortly there will appear on the vision library tape a field named @IAS which is a collection of compiled SUBR"s for performing general matrix row reduction and inversions. For an array A a call (IAS A NEW N M) performs ...
Inverse thermoremanent magnetization
David J. Dunlop
2006-01-01
Inverse thermoremanent magnetization (ITRM) is reversed to the thermoremanent magnetization (TRM) process: ITRM results from warming from low temperature T in a magnetic field, while TRM results from field cooling from high T. The development of ITRM was studied in magnetites of grain sizes from submicron to 135 ?m, in pyrrhotites and in hematite crystals. All three minerals acquired ITRM
Inverses and Elementary Matrices
NSDL National Science Digital Library
Smith, David
Created by David Smith for the Connected Curriculum Project, the purpose of this module is to explore the properties of inverse matrices. Our principal tool for this exploration is the expression of elementary row operations as left multiplications by elementary matrices. This is part of a larger collection of learning modules hosted by Duke University.
Oldenburg, Douglas W.
. Oldenburg1 1. Sky Research, 2. University of British Columbia #12;Waikaloa, Hawaii Waimea, Hawaii Examples. Topography Un-modeled correlated signal will negatively affect estimated dipole parameters #12;UBC 2. Investigating the effects of magnetic topography Conclusion #12;UBC Geophysical Inversion
Kinematic modeling of folding above listric propagating thrusts
NASA Astrophysics Data System (ADS)
Cardozo, Nestor; Brandenburg, J. P.
2014-03-01
We describe a kinematic approach to simulate folds above listric propagating thrusts. The model is based on a pre-defined circular thrust geometry with a maximum central angle beyond which the thrust is planar, inclined shear above the circular thrust, and trishear in front of the thrust. Provided the trajectory of thrust propagation is established, the model can be run forward and backwards. We use this last feature to implement a global simulated annealing, inverse modeling strategy. This inverse modeling strategy is applied to synthetic folds as well as two real examples in offshore Venezuela and the Niger Delta toe-thrust system. These three examples illustrate the benefits of the algorithm, particularly in predicting the possible range of models that can fit the structures. Thrust geometry, depth to detachment level, and backlimb geometry have high impact in model parameters such as backlimb shear angle and fault slip; while forelimb geometry is critical to constrain parameters such as fault propagation to fault slip ratio and trishear angle. Steep to overturned beds in forelimb areas are often not imaged by seismic, so in the absence of additional well data, considering all possible thrust-fold geometries is critical for the modeling and whatever prediction (e.g. hydrocarbon trap integrity) is made from it.
Uncertainty Quantification in Finite-Fault Earthquake Source Inversions: The SIV project
NASA Astrophysics Data System (ADS)
Mai, P. M.; Gallovic, F.
2013-12-01
Finite-fault source inversions estimate kinematic rupture parameters of earthquakes using a variety of available data sets and inversion approaches. Rupture models are obtained by solving an inherently ill-posed inverse problem, subject to numerous a priori assumptions and noisy observations. Despite these limitations, near real-time source inversions are becoming increasingly popular, while we still face the dilemma that uncertainties in such finite-fault source inversions are poorly understood. Yet, the accurate estimation of earthquake rupture properties, including proper uncertainty quantification, is critically important for earthquake seismology and seismic hazard analysis, as they help to adequately characterize earthquake complexity across all scales. The Source Inversion Validation (SIV) project (http://equake-rc.info/sivdb) is a multi-institutional collaboration that attempts to quantify the intra-event variability in rupture models (see the SRCMOD database, http://equake-rc.info/srcmod), and that aims to develop robust uncertainty metrics for earthquake source inversions. The SIV collaboration features an open online platform to examine the current state-of-the-art in earthquake source inversion, but also to test novel source inversion approaches, based on a sequence of benchmark exercises with variable degree of complexity. In this presentation, we summarize initial SIV results related to previous benchmark exercises, discuss the latest findings for a test case of a complex rupture embedded in a 3D heterogeneous Earth model, and propose metrics to quantify rupture-model variability, quality of data fitting, and model robustness.
Inverse and forward numerical modeling of trishear fault-propagation folds
NASA Astrophysics Data System (ADS)
Allmendinger, Richard W.
1998-08-01
Fault-propagation folds commonly display footwall synclines as well as changes in stratigraphic thickness and dip on their forelimbs, features that cannot easily be explained by simple parallel kink fold kinematics. An alternative kinematic model, trishear, can explain these observations, as well as a variety of other features which have long intrigued structural geologists. Trishear has received little attention until recently, in part because it must be applied numerically rather than graphically. A new computer program has been developed to analyze trishear and hybrid trishear-fault-bend fold deformation. Trishear fold shape can vary considerably by changing the apical angle of the trishear zone and/or the propagation to slip ratio (P/S) during the evolution of the structure. Breakouts, anticlinal and synclinal ramps, and inversion structures can also be modeled, tracking the kinematics with growth strata. Strain within trishear zones can be used to predict fracture orientations throughout the structures as demonstrated by comparison with analog clay models. Also presented is a method for inverting data on real structures for a best fit trishear model by performing a grid search over a six-parameter space (ramp angle, trishear apical angle, displacement, P/S, and X and Y positions of the fault tip line). The inversion is performed by restoring a key bed to a planar orientation by least squares regression. Because trishear provides a bulk kinematic description of a deforming zone, it is complementary to, rather than competing with, other kinematic models.
ModEM: A modular system for inversion of elecgtromagnetic geophysical data
NASA Astrophysics Data System (ADS)
Egbert, G. D.; Kelbert, A.; Meqbel, N.; Weng, A.
2010-12-01
We have developed a modular system of computer codes for inversion of electromagnetic (EM) geophysical data (ModEM). ModEM allows for rapid adaptation of inversion algorithms developed for one purpose (e.g., three-dimensional magnetotellurics (MT)) to other EM problems (e.g., controlled source EM). The modular approach can also simplify maintenance of the inversion code, as well as development of new capabilities -- e.g., allowing for new data types such as the inter-site transfer functions in MT, or modifying model regularization. Basic data objects (model parameters, solution vectors, data vectors) are treated as abstract data types, with a standard set of methods developed for each class, including creation and destruction, and, as appropriate, linear algebra or other vector space methods. Operators required for gradient computations are developed as mappings between these basic object classes. Only these abstract data objects and mappings are manipulated by higher level Jacobian and inversion routines, with no reference to the problem specific details required for a specific EM method, or for the numerical implementation of the forward solver. Required problem-specific components are instantiated at the lowest levels of the system, with details hidden from generic top-level routines by an interface layer. Parallelization using MPI has been implemented at the top level, and is thus applicable to any problem embedded in ModEM. To illustrate the flexibility of the system, we consider applications to two- and three-dimensional MT inversion, as well as simple controlled source EM problems.
The inversion of geodetic data for earthquake parameters
NASA Astrophysics Data System (ADS)
Lohman, Rowena
2004-12-01
The spatial and temporal coverage of geodetic data sets such as Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System (GPS) is increasing to the point where we can constrain many aspects of the deformation associated with earthquakes and volcanic eruptions. As our understanding of the kinematics of deformation improves, we can begin to explore the dynamic processes that drive seismic and volcanic deformation in tectonically active regions around the world. In this thesis, I use InSAR data in inversions for earthquake source parameters for both small (4.0 < Mw < 5.5) and large (Mw > 7) earthquakes. For small earthquakes, I focus on constraining the hypocenter location and seismic moment. I examine data for small earthquakes in the Basin and Range province of the Western United States, and in the Zagros mountains of Southern Iran. For large earthquakes, I place constraints on the coseismic slip distribution for a pre-determined fault plane geometry and explore how sensitive the inversion is to inadequacies in the fault plane parameterization. I perform inversions for both the 1999 Mw 7.1 Hector Mine earthquake in Southern California and the 1995 Mw 8.1 Antofagasta earthquake in Chile. I also describe some advances in the technical details of using InSAR observations in inversions for deformation source parameters. I use the full noise covariance matrix in my inversions and compare inferred noise covariances for several interferograms covering the Mojave desert, Southern California, with GPS observations of tropospheric structure functions. I provide an algorithm for resampling (or averaging) InSAR data to minimize the computational burden by reducing the number of data points used as input to inversions. I also explore techniques for regularizing poorly determined inversions of geodetic data for coseismic fault slip.
Kinematic dynamo of inertial waves
NASA Astrophysics Data System (ADS)
Herreman, Wietze; Le Gal, Patrice; Le Dizes, Stephane
2008-11-01
Inertial waves are natural oscillatory tridimensional perturbations in rapidly rotating flows. They can be driven to high amplitudes by an external oscillatory forcing such as precession, or by a parametric instability such as in the elliptical instability. Inertial waves were observed in a MHD-flow (Gans, 1971, JFM ; Kelley et al., 2008, GAFD) and could be responsable of dynamo action. For travelling waves, a constructive alpha-effect was identified (Moffatt, 1970, JFM), but it does not apply to confined inertial wave flows. Yet, recent numerical work demonstrated that precession driven MHD flows can sustain magnetic fields (Tilgner, 2005, POF; Wu & Roberts, 2008, GAFD). This motivates us to study more precisely how inertial waves can exhibit dynamo action. Using a numerical code in cylindrical geometry, we find that standing inertial waves can generate a kinematic dynamo. We show that the dynamo-action results from a second order interaction of the diffusive eigenmodes of the magnetic field with the inertial wave. Scaling laws are obtained, which allows us to to apply the results to flows of geophysical interest.
Edge-driven microplate kinematics
Schouten, Hans; Klitgord, Kim D.; Gallo, David G.
1993-01-01
It is known from plate tectonic reconstructions that oceanic microplates undergo rapid rotation about a vertical axis and that the instantaneous rotation axes describing the microplate's motion relative to the bounding major plates are frequently located close to its margins with those plates, close to the tips of propagating rifts. We propose a class of edge-driven block models to illustrate how slip across the microplate margins, block rotation, and propagation of rifting may be related to the relative motion of the plates on either side. An important feature of these edge-driven models is that the instantaneous rotation axes are always located on the margins between block and two bounding plates. According to those models the pseudofaults or traces of disrupted seafloor resulting from the propagation of rifting between microplate and major plates may be used independently to approximately trace the continuous kinematic evolution of the microplate back in time. Pseudofault geometries and matching rotations of the Easter microplate show that for most of its 5 m.y. history, block rotation could be driven by the drag of the Nazca and Pacific plates on the microplate's edges rather than by a shear flow of mantle underneath.
NASA Astrophysics Data System (ADS)
Kim, Sunghwan; Mitropoulos, Alexander N.; Spitzberg, Joshua D.; Tao, Hu; Kaplan, David L.; Omenetto, Fiorenzo G.
2012-12-01
Periodic nanostructures provide the facility to control and manipulate the flow of light through their lattices. Three-dimensional photonic crystals enable the controlled design of structural colour, which can be varied by infiltrating the structure with different (typically liquid) fillers. Here, we report three-dimensional photonic crystals composed entirely of a purified natural protein (silk fibroin). The biocompatibility of this protein, as well as its favourable material properties and ease of biological functionalization, present opportunities for otherwise unattainable device applications such as bioresorbable integration of structural colour within living tissue or lattice functionalization by means of organic and inorganic material doping. We present a silk inverse opal that demonstrates a pseudo-photonic bandgap in the visible spectrum and show its associated structural colour beneath biological tissue. We also leverage silk's facile dopability to manufacture a gold nanoparticle silk inverse opal and demonstrate patterned heating mediated by enhancement of nanoparticle absorption at the band-edge frequency of the photonic crystal.
NSDL National Science Digital Library
Annenberg Media
2009-12-23
"Lesson 1 of two lessons teaches students about direct variation by allowing them to explore a simulated oil spill using toilet paper tissues (to represent land) and drops of vegetable oil (to simulate a volume of oil). Lesson 2 teaches students about inverse variation by exploring the relationship between the heights of a fixed amount of water poured into cylindrical containers of different sizes as compared to the area of the containers' bases." from Insights into Algebra 1 - Annenberg Foundation.
Benjamin C.-Y. Lu; Paul Yu; David P. L. Poon
1970-01-01
THE phase behaviour of the nitrogen-methane-ethane system in the vicinity of -255° F has been reported in an earlier communication1. The system has subsequently been studied at lower temperatures by lowering the freezing point of the isopentane bath liquid with propane gas. It was found that a liquid phase inversion took place between the temperatures -255° F and -263.3° F,
Dexterous Robotic Hands: Kinematics and Control
Narasimhan, Sundar
1988-11-01
This report presents issues relating to the kinematics and control of dexterous robotic hands using the Utah-MIT hand as an illustrative example. The emphasis throughout is on the actual implementation and testing of ...
Spheroid ages, kinematics and BH relations
Eric Emsellem
2006-11-02
I very briefly discuss the ages and kinematics of spheroids as well as the black hole relations, via a few recent and illustrative studies, which include results on the downsizing, scaling laws, angular momentum and central massive objects.
Kinematic View of Loop Closure A. COUTSIAS,
Coutsias, Evangelos
polynomial in variable, on robotics literature kinematics equivalent rotator linkage most general oblique in conformational sampling. Unlike Cartesian moves, geometric distortions high energy penalty entail. other hand systems objects connected flexible joints, as multijointed robotic manipu lators, exhibits many
Intersections, ideals, and inversion
Vasco, D.W.
1998-10-01
Techniques from computational algebra provide a framework for treating large classes of inverse problems. In particular, the discretization of many types of integral equations and of partial differential equations with undetermined coefficients lead to systems of polynomial equations. The structure of the solution set of such equations may be examined using algebraic techniques.. For example, the existence and dimensionality of the solution set may be determined. Furthermore, it is possible to bound the total number of solutions. The approach is illustrated by a numerical application to the inverse problem associated with the Helmholtz equation. The algebraic methods are used in the inversion of a set of transverse electric (TE) mode magnetotelluric data from Antarctica. The existence of solutions is demonstrated and the number of solutions is found to be finite, bounded from above at 50. The best fitting structure is dominantly onedimensional with a low crustal resistivity of about 2 ohm-m. Such a low value is compatible with studies suggesting lower surface wave velocities than found in typical stable cratons.
Kinematical X-Ray Standing Waves
NASA Astrophysics Data System (ADS)
Tolkiehn, Martin; Novikov, Dmitri V.
2013-01-01
We present a theoretical investigation and experimental proof of X-ray standing wave formation in mosaic crystals under weak diffracted beam conditions. The obtained standing wave phase dependence, described using the kinematical approximation, is valid at large deviations from the Bragg angle for non-perfect crystals as well as for ideal crystals. The presented theory represents the basis for a novel variation of the XSW method, called kinematical X-ray standing waves.
Kinematics in Hickson Compact Group 90
NASA Astrophysics Data System (ADS)
Castañeda, Leonardo; Hilker, Michael
2004-08-01
Using long-slit spectra observed at the VLT (ESO, Paranal) in May 2002, we studied the stellar kinematics in the core of the Hickson Compact Group 90. The line of sight velocity distribution (LOSVD), the velocity dispersion profiles and the Hermite moments h3,h4 along two slit positions are presented. The comparison with previous results is discussed. For kinematical analysis we used the parametrization for the LOSVD given in van der Marel et al. (1993).
Kinematic Wave Models of Network Vehicular Traffic Wenlong Jin
Jin, Wenlong
Kinematic Wave Models of Network Vehicular Traffic By Wenlong Jin B.S. (University of Science Applied Mathematics Kinematic Wave Models of Network Vehicular Traffic Abstract The kinematic wave theory vehicular traffic. In this dissertation, we study kinematic wave models of network traffic, which
Radial Kinematics of Isolated Elliptical Galaxies
George Hau; Duncan Forbes
2006-04-21
Ellipticals in very low density environments are extremely rare but hold important clues about galaxy formation and evolution. In this paper we continue our study of isolated elliptical galaxies, presenting results on the radial stellar kinematics for 13 isolated early-type galaxies. We derive radial rotation velocity, velocity dispersion and hermite terms to ~1 effective radius. We observe a dichotomy in kinematic properties similar to that in the elliptical population as a whole, where low luminosity ellipticals tend to be rotationally supported. For all galaxies the V/sigma ratio increases with radius. We find kinematically distinct cores (KDCs), or velocity substructure, in ~40% of the galaxies for which we have major axis spectra. Such a fraction is similar to that observed for ellipticals in higher density environments. Most galaxies in the sample reveal kinematic evidence for a nuclear disk. The non-relaxed kinematics in several galaxies suggests that they have undergone a merger or accretion event. Isolated ellipticals generally follow the fundamental plane defined by cluster ellipticals -- exceptions being those galaxies with evidence for young stellar populations. Overall, we find isolated ellipticals have similar kinematic properties to their counterparts in higher density environments.
Hickson 62.I. Kinematics of NGC4778
M. Spavone; E. Iodice; G. Longo; M. Paolillo; S. Sodani
2006-06-30
Detailed studies of the photometric and kinematical properties of compact groups of galaxies are crucial to understand the physics of galaxy interactions and to shed light on some aspects of galaxy formation and evolution. In this paper we present a kinematical and photometrical study of a member, NGC4778, of the nearest (z=0.0137) compact group: Hickson 62. Aims: The aim of this work was to investigate the existence of kinematical anomalies in the brightest group member, NGC4778 in order to constrain the dynamical status and the formation history of the group. Methods: We used long-slit spectra obtained with FORS1 at VLT, to measure line-of-sight velocity distributions by means of the Fourier Correlation Quotient method, and to derive the galaxy rotation curve and velocity dispersion profile. Results: Our analysis reveals that Hickson 62a, also known as NGC4778, is an S0 galaxy with kinematical and morphological peculiarities, both in its central regions (r kinematically decoupled stellar component, offset with respect to the photometric center. In the outer halo we find an asymmetric rotation curve and a velocity dispersion profile showing a rise on the SW side, in direction of the galaxy NGC4776. Conclusions: The nuclear counterrotation, the distorted kinematics in the outer halo and the X-ray properties of the group suggest that NGC4778 may be the product of a recent minor merger, more reliable with a small late-type galaxy.
Stiffness of a 3-degree of freedom translational parallel kinematic machine
NASA Astrophysics Data System (ADS)
Shankar Ganesh, S.; Koteswara Rao, A. B.
2014-09-01
In this paper, a typical 3-degree of freedom (3-DOF) translational parallel kinematic machine (PKM) is studied and analyzed whose tool platform has only translations along X-, Y- and Z-axes. It consists of three limbs, each of which have arm and forearm with prismatic-revolute-revolute-revolute (PRRR) joints. Inverse kinematics analysis is carried out to find the slider coordinates and joint angles for a given position of tool platform. Stiffness modeling is done based on the compliance matrices of arm and forearm of each limb. Using the stiffness modeling the variations of minimum and maximum translational stiffness in the workspace are analyzed. For various architectural parameters of the 3-DOF PKM the tendency of variations on the minimum and maximum stiffness over the entire workspace is studied; and also the deflections of the tool platform along X, Y, and Z directions with respect to various forces are presented.
Stiffness of a 3-degree of freedom translational parallel kinematic machine
NASA Astrophysics Data System (ADS)
Shankar Ganesh, S.; Koteswara Rao, A. B.
2014-09-01
In this paper, a typical 3-degree of freedom (3- DOF) translational parallel kinematic machine (PKM) is studied and analyzed whose tool platform has only translations along X-, Y- and Z-axes. It consists of three limbs, each of which have arm and forearm with prismaticrevolute- revolute-revolute (PRRR) joints. Inverse kinematics analysis is carried out to find the slider coordinates and joint angles for a given position of tool platform. Stiffness modeling is done based on the compliance matrices of arm and forearm of each limb. Using the stiffness modeling the variations of minimum and maximum translational stiffness in the workspace are analyzed. For various architectural parameters of the 3-DOF PKM the tendency of variations on the minimum and maximum stiffness over the entire workspace is studied; and also the deflections of the tool platform along X, Y, and Z directions with respect to various forces are presented.
NASA Technical Reports Server (NTRS)
Hennessey, Michael P.; Huang, Paul C.; Bunnell, Charles T.
1989-01-01
An efficient approach to cartesian motion and force control of a 7 degree of freedom (DOF) manipulator is presented. It is based on extending the active stiffness controller to the 7 DOF case in general and use of an efficient version of the gradient projection technique for solving the inverse kinematics problem. Cooperative control is achieved through appropriate configuration of individual manipulator controllers. In addition, other aspects of trajectory generation using standard techniques are integrated into the controller. The method is then applied to a specific manipulator of interest (Robotics Research T-710). Simulation of the kinematics, dynamics, and control are provided in the context of several scenarios: one pertaining to a noncontact pick and place operation; one relating to contour following where contact is made between the manipulator and environment; and one pertaining to cooperative control.
Foot kinematics and loading of professional athletes in American football-specific tasks.
Riley, Patrick O; Kent, Richard W; Dierks, Tracy A; Lievers, W Brent; Frimenko, Rebecca E; Crandall, Jeff R
2013-09-01
The purpose of this study was to describe stance foot and ankle kinematics and the associated ground reaction forces at the upper end of human performance in professional football players during commonly performed football-specific tasks. Nine participants were recruited from the spring training squad of a professional football team. In a motion analysis laboratory setting, participants performed three activities used at the NFL Scouting Combine to assess player speed and agility: the 3-cone drill, the shuttle run, and the standing high jump. The talocrural and first metatarsophalangial joint dorsiflexion, subtalar joint inversion, and the ground reaction forces were determined for the load bearing portions of each activity. We documented load-bearing foot and ankle kinematics of elite football players performing competition-simulating activities, and confirmed our hypothesis that the talocrural, subtalar, and metatarsophalangeal joint ranges of motion for the activities studied approached or exceeded reported physiological limits. PMID:22591791
Hierarchical Bayesian Inversion for the Centroid Moment Tensor
NASA Astrophysics Data System (ADS)
Mustac, M.; Tkalcic, H.
2014-12-01
Kinematic point source inversions using data from complex tectonic settings (e.g. geothermal or volcanic areas and mines) often result in large non-double-couple components. Examining events with mechanisms more complex than shear motion on a planar fault requires a sophisticated inversion method. We have developed a technique within the probabilistic Bayesian framework that combines previous knowledge about the mechanism with the information from the data and results in a posterior probability distribution for the model parameters. It is capable of yielding parameter uncertainties, which cannot be analytically calculated for a non-linear inversion that includes the source location. The code uses time-series of displacements of regional earthquakes and explosions with moderate magnitudes to compute the centroid location and the seismic moment tensor. The noise is also treated as an unknown in the inversion, in order to determine the level of data fit. As a result, the model complexity (i.e. the contribution of isotropic and compensated linear vector dipole components) is determined by the data themself. Furthermore, the noise weights the contribution of each waveform and the noise covariance matrix accounts for both observational and theoretical errors. The code has been extensively tested in synthetic experiments with a variety of focal mechanisms and different types of noise added to synthetic waveforms. It showed fast convergence of the centroid location, accompanied with thorough sampling of the moment tensor parameters leading to narrow posterior distributions. Subsequently, it is being applied to waveforms from earthquakes that occurred in various tectonic environments.
NASA Astrophysics Data System (ADS)
Knoll, D. A.; Chacon, L.; Evans, K. J.
2009-12-01
Many partial differential equation systems in computational geophysics can be categorized as stiff wave systems. Stiff wave systems are systems which exhibit a slow dynamical time scale while possessing fast wave phenomena. The physical effects of this fast wave may be important to the system, but resolving the fast time scale may not be required. When simulating such phenomena one would like to use time steps on the order of the dynamical scale for time integration. Historically, Semi-Implicit (SI) methods have been developed to step over the stiff wave time scale in a stable fashion. However, SI methods require some linearization and time splitting, and both of these can produce additional time integration errors. In this paper, the concept of using SI methods as preconditioners to Jacobian-Free Newton-Krylov (JFNK) methods is developed. This algorithmic approach results in an implicitly balanced method (no linearization or time splitting). In this presentation, we provide an overview of SI methods in a variety of applications, and a brief background on JFNK methods. We will present details of our combined algorithmic approach. Foundational algorithmic performance results coming from representative problems in geophysical fluid dynamics and magnetohydrodynamics (MHD) will be presented. Following this introduction to the fundamental concepts we will discuss two more detailed directions. First we will present results coming from application of these ideas to 3-D MHD in a large scale parallel computing environment. We will also discuss the impact that these algorithms are having on simulation studies of fast magnetic reconnection. We will discuss the concept of barotropic-baroclinic splitting and the resulting SI algorithm for a free-surface ocean model. We will show how this algorithm can be cast as a preconditioner for a fully-implicit, JFNK based, ocean simulation code. We will also discuss issues related to accuracy and long time integration with some results from atmospheric simulations. Finally, we will briefly discuss the application of JFNK and physics-based preconditioning to other problems in computational geophysics such as sea ice modeling and ice sheet modeling.
Interplanetary stream magnetism - Kinematic effects
NASA Technical Reports Server (NTRS)
Burlaga, L. F.; Barouch, E.
1976-01-01
The particle density and the magnetic-field intensity and direction are calculated for volume elements of the solar wind as a function of the initial magnetic-field direction and the initial speed gradient. It is assumed that the velocity is constant and radial. These assumptions are approximately valid between about 0.1 and 1.0 AU for many streams. Time profiles of the particle density, field intensity, and velocity are calculated for corotating streams, neglecting effects of pressure gradients. The compression and rarefaction of the magnetic field depend sensitively on the initial field direction. By averaging over a typical stream, it is found that the average radial field intensity is inversely proportional to the square of the heliocentric distance, whereas the average intensity in the direction of the planets' motion does not vary in a simple way, consistent with deep space observations. Changes of field direction may be very large, depending on the initial angle; but when the initial angle at 0.1 AU is such that the base of the field line corotates with the sun, the spiral angle is the preferred direction at 1 AU. The theory is also applicable to nonstationary flows.
NSDL National Science Digital Library
This demonstration allows students to visualize inversion in a fluid, explain it in terms of density, and apply the concept to weather systems and convection. Materials required include four Ehrlenmeyer flasks, two thin glass plates, a heat source, and food coloring. The investigation supports material presented in chapter 7, What Causes Thunderstorms and Tornadoes?, in the textbook Energy flow, part of Global System Science, an interdisciplinary course for high school students that emphasizes how scientists from a wide variety of fields work together to understand significant problems of global impact.
NASA Astrophysics Data System (ADS)
Park, Hyeongkae; Nourgaliev, Robert; Knoll, Dana
2007-11-01
The Discontinuous Galerkin (DG) method for compressible fluid flows is incorporated into the Jacobian-Free Newton-Krylov (JFNK) framework. Advantages of combining the DG with the JFNK are two-fold: a) enabling robust and efficient high-order-accurate modeling of all-speed flows on unstructured grids, opening the possibility for high-fidelity simulation of nuclear-power-industry-relevant flows; and b) ability to tightly, robustly and high-order-accurately couple with other relevant physics (neutronics, thermal-structural response of solids, etc.). In the present study, we focus on the physics-based preconditioning (PBP) of the Krylov method (GMRES), used as the linear solver in our implicit higher-order-accurate Runge-Kutta (ESDIRK) time discretization scheme; exploiting the compactness of the spatial discretization of the DG family. In particular, we utilize the Implicit Continuous-fluid Eulerian (ICE) method and investigate its efficacy as the PBP within the JFNK-DG method. Using the eigenvalue analysis, it is found that the ICE collapses the complex components of the all eigenvalues of the Jacobian matrix (associated with pressure waves) onto the real axis, and thereby enabling at least an order of magnitude faster simulations in nearly-incompressible/weakly-compressible regimes with a significant storage saving.
Integrating the Jacobian equation
Airton von Sohsten de Medeiros; Ráderson Rodrigues da Silva
2014-09-16
We show essentially that the differential equation $\\frac{\\partial (P,Q)}{\\partial (x,y)} =c \\in {\\mathbb C}$, for $P,\\,Q \\in {\\mathbb C}[x,y]$, may be "integrated", in the sense that it is equivalent to an algebraic system of equations involving the homogeneous components of $P$ and $Q$. Furthermore, the first equations in this system give explicitly the homogeneous components of $Q$ in terms of those of $P$. The remaining equations involve only the homogeneous components of $P$.
Gait Kinematic Analysis in Water Using Wearable Inertial Magnetic Sensors
Fantozzi, Silvia; Giovanardi, Andrea; Borra, Davide; Gatta, Giorgio
2015-01-01
Walking is one of the fundamental motor tasks executed during aquatic therapy. Previous kinematics analyses conducted using waterproofed video cameras were limited to the sagittal plane and to only one or two consecutive steps. Furthermore, the set-up and post-processing are time-consuming and thus do not allow a prompt assessment of the correct execution of the movements during the aquatic session therapy. The aim of the present study was to estimate the 3D joint kinematics of the lower limbs and thorax-pelvis joints in sagittal and frontal planes during underwater walking using wearable inertial and magnetic sensors. Eleven healthy adults were measured during walking both in shallow water and in dry-land conditions. Eight wearable inertial and magnetic sensors were inserted in waterproofed boxes and fixed to the body segments by means of elastic modular bands. A validated protocol (Outwalk) was used. Gait cycles were automatically segmented and selected if relevant intraclass correlation coefficients values were higher than 0.75. A total of 704 gait cycles for the lower limb joints were normalized in time and averaged to obtain the mean cycle of each joint, among participants. The mean speed in water was 40% lower than that of the dry-land condition. Longer stride duration and shorter stride distance were found in the underwater walking. In the sagittal plane, the knee was more flexed (? 23°) and the ankle more dorsiflexed (? 9°) at heel strike, and the hip was more flexed at toe-off (? 13°) in water than on land. On the frontal plane in the underwater walking, smoother joint angle patterns were observed for thorax-pelvis and hip, and ankle was more inversed at toe-off (? 7°) and showed a more inversed mean value (? 7°). The results were mainly explained by the effect of the speed in the water as supported by the linear mixed models analysis performed. Thus, it seemed that the combination of speed and environment triggered modifications in the joint angles in underwater gait more than these two factors considered separately. The inertial and magnetic sensors, by means of fast set-up and data analysis, can supply an immediate gait analysis report to the therapist during the aquatic therapy session. PMID:26368131
Kinematic and Spatial Substructure in NGC 2264
NASA Astrophysics Data System (ADS)
Tobin, John J.; Hartmann, Lee; F?rész, Gabor; Hsu, Wen-Hsin; Mateo, Mario
2015-04-01
We present an expanded kinematic study of the young cluster NGC 2264 based upon optical radial velocities measured using multi-fiber echelle spectroscopy at the 6.5 m MMT and Magellan telescopes. We report radial velocities for 695 stars, of which approximately 407 stars are confirmed or very likely members. Our results more than double the number of members with radial velocities from F?rész et al., resulting in a much better defined kinematic relationship between the stellar population and the associated molecular gas. In particular, we find that there is a significant subset of stars that are systematically blueshifted with respect to the molecular (13CO) gas. The detection of Lithium absorption and/or infrared excesses in this blueshifted population suggests that at least some of these stars are cluster members; we suggest some speculative scenarios to explain their kinematics. Our results also more clearly define the redshifted population of stars in the northern end of the cluster; we suggest that the stellar and gas kinematics of this region are the result of a bubble driven by the wind from O7 star S Mon. Our results emphasize the complexity of the spatial and kinematic structure of NGC 2264, important for eventually building up a comprehensive picture of cluster formation. Observations reported here were obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.
Graph Theory Roots of Spatial Operators for Kinematics and Dynamics
NASA Technical Reports Server (NTRS)
Jain, Abhinandan
2011-01-01
Spatial operators have been used to analyze the dynamics of robotic multibody systems and to develop novel computational dynamics algorithms. Mass matrix factorization, inversion, diagonalization, and linearization are among several new insights obtained using such operators. While initially developed for serial rigid body manipulators, the spatial operators and the related mathematical analysis have been shown to extend very broadly including to tree and closed topology systems, to systems with flexible joints, links, etc. This work uses concepts from graph theory to explore the mathematical foundations of spatial operators. The goal is to study and characterize the properties of the spatial operators at an abstract level so that they can be applied to a broader range of dynamics problems. The rich mathematical properties of the kinematics and dynamics of robotic multibody systems has been an area of strong research interest for several decades. These properties are important to understand the inherent physical behavior of systems, for stability and control analysis, for the development of computational algorithms, and for model development of faithful models. Recurring patterns in spatial operators leads one to ask the more abstract question about the properties and characteristics of spatial operators that make them so broadly applicable. The idea is to step back from the specific application systems, and understand more deeply the generic requirements and properties of spatial operators, so that the insights and techniques are readily available across different kinematics and dynamics problems. In this work, techniques from graph theory were used to explore the abstract basis for the spatial operators. The close relationship between the mathematical properties of adjacency matrices for graphs and those of spatial operators and their kernels were established. The connections hold across very basic requirements on the system topology, the nature of the component bodies, the indexing schemes, etc. The relationship of the underlying structure is intimately connected with efficient, recursive computational algorithms. The results provide the foundational groundwork for a much broader look at the key problems in kinematics and dynamics. The properties of general graphs and trees of nodes and edge were examined, as well as the properties of adjacency matrices that are used to describe graph connectivity. The nilpotency property of such matrices for directed trees was reviewed, and the adjacency matrices were generalized to the notion of block weighted adjacency matrices that support block matrix elements. This leads us to the development of the notion of Spatial Kernel Operator SKO kernels. These kernels provide the basis for the development of SKO resolvent operators.
Kinetic and kinematic differences between deadlifts and goodmornings
2013-01-01
Background In order to improve training performance, as well as avoid overloading during prevention and rehabilitation exercises in patients, the aim of this study was to understand the biomechanical differences in the knee, hip and the back between the exercises “Goodmornings” (GMs) and “Deadlifts” (DLs). Methods The kinetics and kinematics of 13 subjects, performing GMs and DLs with an additional 25% (GMs), 25% and 50% (DLs) body weight (BW) on the barbell were analysed. Using the kinetic and kinematic data captured using a 3D motion analysis and force plates, an inverse approach with a quasi-static solution was used to calculate the sagittal moments and angles in the knee, hip and the trunk. The maximum moments and joint angles were statistically tested using ANOVA with a Bonferroni adjustment. Results The observed maximal flexion angle of the knee was 5.3?±?6.7° for GMs and 107.8?±?22.4° and 103.4?±?22.6° for DLs with 25% and 50% BW respectively. Of the hip, the maximal flexion angle was 25% smaller during GMs compared to DLs. No difference in kinematics of the trunk between the two exercises was observed. For DLs, the resulting sagittal moment in the knee was an external flexion moment, whereas during GMs an external extension moment was present. Importantly, no larger sagittal knee joint moments were observed when using a heavier weight on the barbell during DLs, but higher sagittal moments were found at the hip and L4/L5. Compared to GMs, DLs produced a lower sagittal moment at the hip using 25% BW while generating the same sagittal moment at L4/L5. Conclusions The two exercises exhibited different motion patterns for the lower extremities but not for the trunk. To strengthen the hip while including a large range of motion, DLs using 50% BW should be chosen. Due to their ability to avoid knee flexion or a knee flexion moment, GMs should be preferentially chosen over DLs as ACL rupture prevention exercises. Here, in order to shift the hamstring to quadriceps ratio towards the hamstrings, GMs should be favoured ahead of DLs using 50% BW before DLs using 25% BW. PMID:24314057
Adaptive Core Simulation Employing Discrete Inverse Theory - Part I: Theory
Abdel-Khalik, Hany S.; Turinsky, Paul J.
2005-07-15
Use of adaptive simulation is intended to improve the fidelity and robustness of important core attribute predictions such as core power distribution, thermal margins, and core reactivity. Adaptive simulation utilizes a selected set of past and current reactor measurements of reactor observables, i.e., in-core instrumentation readings, to adapt the simulation in a meaningful way. A meaningful adaption will result in high-fidelity and robust adapted core simulator models. To perform adaption, we propose an inverse theory approach in which the multitudes of input data to core simulators, i.e., reactor physics and thermal-hydraulic data, are to be adjusted to improve agreement with measured observables while keeping core simulator models unadapted. At first glance, devising such adaption for typical core simulators with millions of input and observables data would spawn not only several prohibitive challenges but also numerous disparaging concerns. The challenges include the computational burdens of the sensitivity-type calculations required to construct Jacobian operators for the core simulator models. Also, the computational burdens of the uncertainty-type calculations required to estimate the uncertainty information of core simulator input data present a demanding challenge. The concerns however are mainly related to the reliability of the adjusted input data. The methodologies of adaptive simulation are well established in the literature of data adjustment. We adopt the same general framework for data adjustment; however, we refrain from solving the fundamental adjustment equations in a conventional manner. We demonstrate the use of our so-called Efficient Subspace Methods (ESMs) to overcome the computational and storage burdens associated with the core adaption problem. We illustrate the successful use of ESM-based adaptive techniques for a typical boiling water reactor core simulator adaption problem.
Inverse problem for Bremsstrahlung radiation
Voss, K.E.; Fisch, N.J.
1991-10-01
For certain predominantly one-dimensional distribution functions, an analytic inversion has been found which yields the velocity distribution of superthermal electrons given their Bremsstrahlung radiation. 5 refs.
Kinematics of Diffuse Ionized Gas Halos
R. J. Rand
2004-09-22
Existing long-slit spectral data for edge-on spiral galaxies suggesting that their Diffuse Ionized Gas (DIG) halos rotate slower than their underlying disks are summarized. An attempt to characterize lagging halos using a model of purely ballistic disk-halo flow is discussed, with the result that the model fails badly for the lagging halo of NGC 891, but is somewhat more successful for NGC 5775. New two-dimensional kinematic data on the DIG halo of NGC 4302 are presented, along with a preliminary analysis of its rotation. Two-dimensional data on NGC 5775 and a preliminary analysis of its halo rotation is discussed by Heald et al. (this volume). The halo of NGC 4302 shows clear signs of lagging on its approaching side, but also strong indications of peculiar kinematics. The kinematics of the receding side are more complex.
Kinematics of Diffuse Ionized Gas Halos
Rand, R J
2004-01-01
Existing long-slit spectral data for edge-on spiral galaxies suggesting that their Diffuse Ionized Gas (DIG) halos rotate slower than their underlying disks are summarized. An attempt to characterize lagging halos using a model of purely ballistic disk-halo flow is discussed, with the result that the model fails badly for the lagging halo of NGC 891, but is somewhat more successful for NGC 5775. New two-dimensional kinematic data on the DIG halo of NGC 4302 are presented, along with a preliminary analysis of its rotation. Two-dimensional data on NGC 5775 and a preliminary analysis of its halo rotation is discussed by Heald et al. (this volume). The halo of NGC 4302 shows clear signs of lagging on its approaching side, but also strong indications of peculiar kinematics. The kinematics of the receding side are more complex.
Dark energy as a kinematic effect
Jennen, H
2015-01-01
We present a generalization of teleparallel gravity that is consistent with local spacetime kinematics regulated by the de Sitter group $SO(1,4)$. The mathematical structure of teleparallel gravity is shown to be given by a nonlinear Riemann--Cartan geometry without curvature, which inspires us to build the generalization on top of a de Sitter--Cartan geometry with a cosmological function. The cosmological function is given its own dynamics and naturally emerges nonminimally coupled to the gravitational field in a manner akin to teleparallel dark energy models or scalar-tensor theories in general relativity. New in the theory here presented, the cosmological function gives rise to a kinematic contribution in the deviation equation for the world lines of adjacent free-falling particles. While having its own dynamics, dark energy manifests itself in the local kinematics of spacetime.
Dark energy as a kinematic effect
H. Jennen; J. G. Pereira
2015-06-05
We present a generalization of teleparallel gravity that is consistent with local spacetime kinematics regulated by the de Sitter group $SO(1,4)$. The mathematical structure of teleparallel gravity is shown to be given by a nonlinear Riemann--Cartan geometry without curvature, which inspires us to build the generalization on top of a de Sitter--Cartan geometry with a cosmological function. The cosmological function is given its own dynamics and naturally emerges nonminimally coupled to the gravitational field in a manner akin to teleparallel dark energy models or scalar-tensor theories in general relativity. New in the theory here presented, the cosmological function gives rise to a kinematic contribution in the deviation equation for the world lines of adjacent free-falling particles. While having its own dynamics, dark energy manifests itself in the local kinematics of spacetime.
Kinematics of the most efficient cilium
Christophe Eloy; Eric Lauga
2012-04-27
In a variety of biological processes, eukaryotic cells use cilia to transport flow. Although cilia have a remarkably conserved internal molecular structure, experimental observations report very diverse kinematics. To address this diversity, we determine numerically the kinematics and energetics of the most efficient cilium. Specifically, we compute the time-periodic deformation of a wall-bound elastic filament leading to transport of a surrounding fluid at minimum energetic cost, where the cost is taken to be the positive work done by all internal molecular motors. The optimal kinematics are found to strongly depend on the cilium bending rigidity through a single dimensionless number, the Sperm number, and closely resemble the two-stroke ciliary beating pattern observed experimentally.
Kinematics and Control of Robot Manipulators
NASA Astrophysics Data System (ADS)
Paden, Bradley Evan
This dissertation focuses on the kinematics and control of robot manipulators. The contribution to kinematics is a fundamental theorem on the design of manipulators with six revolute joints. The theorem states, roughly speaking, that manipulators which have six revolute joints and are modeled after the human arm are optimal and essentially unique. In developing the mathematical framework to prove this theorem, we define precisely the notions of length of a manipulator, well-connected-workspace, and work-volume. We contribute to control a set of analysis techniques for the design of variable structure (sliding mode) controllers for manipulators. The organization of the dissertation is the following. After introductory remarks in chapter one, the group of proper rigid motions, G, is introduced in chapter two. The tangent bundle of G is introduced and it is shown that the velocity of a rigid body can be represented by an element in the Lie algebra of G (commonly called a twist). Further, rigid motions which are exponentials of twists are used to describe four commonly occurring subproblems in robot kinematics. In chapter three, the exponentials of twists are used to write the forward kinematic map of robot manipulators and the subproblems of chapter two are used to solve the Stanford manipulator and an elbow manipulator. Chapter four focuses on manipulator singularities. Twist coordinates are used to find critical points of the forward kinematic map. The contribution to kinematics is contained in chapter five where a mathematical framework for studying the relationship between the design of 6R manipulators and their performance is developed. Chapter seven contains the contribution to control. The work of A. F. Filippov on differential equations with discontinuous right-hand-side and the work of F. H. Clarke on generalized gradients are combined to obtain a calculus for analyzing nonsmooth gradient systems. The techniques developed are applied to design a simple variable structure controller for the nonlinear dynamics of robot manipulators.
Particle Kinematics in Horava-Lifshitz Gravity
Capasso, Dario
2009-01-01
We study the deformed kinematics of point particles in the Horava theory of gravity. This is achieved by considering particles as the optical limit of fields with a generalized Klein-Gordon action. We derive the deformed geodesic equation and study in detail the cases of flat and spherically symmetric (Schwarzschild-like) spacetimes. As the theory is not invariant under local Lorenz transformations, deviations from standard kinematics become evident even for flat manifolds, supporting superluminal as well as massive luminal particles. These deviations from standard behavior could be used for experimental tests of this modified theory of gravity.
Particle Kinematics in Horava-Lifshitz Gravity
Dario Capasso; Alexios P. Polychronakos
2009-10-07
We study the deformed kinematics of point particles in the Horava theory of gravity. This is achieved by considering particles as the optical limit of fields with a generalized Klein-Gordon action. We derive the deformed geodesic equation and study in detail the cases of flat and spherically symmetric (Schwarzschild-like) spacetimes. As the theory is not invariant under local Lorenz transformations, deviations from standard kinematics become evident even for flat manifolds, supporting superluminal as well as massive luminal particles. These deviations from standard behavior could be used for experimental tests of this modified theory of gravity.
Inverse problem in hydrogeology
NASA Astrophysics Data System (ADS)
Carrera, Jesús; Alcolea, Andrés; Medina, Agustín; Hidalgo, Juan; Slooten, Luit J.
2005-03-01
The state of the groundwater inverse problem is synthesized. Emphasis is placed on aquifer characterization, where modelers have to deal with conceptual model uncertainty (notably spatial and temporal variability), scale dependence, many types of unknown parameters (transmissivity, recharge, boundary conditions, etc.), nonlinearity, and often low sensitivity of state variables (typically heads and concentrations) to aquifer properties. Because of these difficulties, calibration cannot be separated from the modeling process, as it is sometimes done in other fields. Instead, it should be viewed as one step in the process of understanding aquifer behavior. In fact, it is shown that actual parameter estimation methods do not differ from each other in the essence, though they may differ in the computational details. It is argued that there is ample room for improvement in groundwater inversion: development of user-friendly codes, accommodation of variability through geostatistics, incorporation of geological information and different types of data (temperature, occurrence and concentration of isotopes, age, etc.), proper accounting of uncertainty, etc. Despite this, even with existing codes, automatic calibration facilitates enormously the task of modeling. Therefore, it is contended that its use should become standard practice. L'état du problème inverse des eaux souterraines est synthétisé. L'accent est placé sur la caractérisation de l'aquifère, où les modélisateurs doivent jouer avec l'incertitude des modèles conceptuels (notamment la variabilité spatiale et temporelle), les facteurs d'échelle, plusieurs inconnues sur différents paramètres (transmissivité, recharge, conditions aux limites, etc.), la non linéarité, et souvent la sensibilité de plusieurs variables d'état (charges hydrauliques, concentrations) des propriétés de l'aquifère. A cause de ces difficultés, le calibrage ne peut êtreséparé du processus de modélisation, comme c'est le cas dans d'autres cas de figure. Par ailleurs, il peut être vu comme une des étapes dans le processus de détermination du comportement de l'aquifère. Il est montré que les méthodes d'évaluation des paramètres actuels ne diffèrent pas si ce n'est dans les détails des calculs informatiques. Il est montré qu'il existe une large panoplie de techniques d'inversion : codes de calcul utilisables par tout-un-chacun, accommodation de la variabilité via la géostatistique, incorporation d'informations géologiques et de différents types de données (température, occurrence, concentration en isotopes, âge, etc.), détermination de l'incertitude. Vu ces développements, la calibration automatique facilite énormément la modélisation. Par ailleurs, il est souhaitable que son utilisation devienne une pratique standardisée. Se sintetiza el estado del problema inverso en aguas subterráneas. El énfasis se ubica en la caracterización de acuíferos, donde los modeladores tienen que enfrentar la incertidumbre del modelo conceptual (principalmente variabilidad temporal y espacial), dependencia de escala, muchos tipos de parámetros desconocidos (transmisividad, recarga, condiciones limitantes, etc), no linealidad, y frecuentemente baja sensibilidad de variables de estado (típicamente presiones y concentraciones) a las propiedades del acuífero. Debido a estas dificultades, no puede separarse la calibración de los procesos de modelado, como frecuentemente se hace en otros campos. En su lugar, debe de visualizarse como un paso en el proceso de enten dimiento del comportamiento del acuífero. En realidad, se muestra que los métodos reales de estimación de parámetros no difieren uno del otro en lo esencial, aunque sí pueden diferir en los detalles computacionales. Se discute que existe amplio espacio para la mejora del problema inverso en aguas subterráneas: desarrollo de códigos amigables alusuario, acomodamiento de variabilidad a través de geoestadística, incorporación de información geológica y diferentes tipos de datos (temperatura, presencia y co
The equations of the inverse kinematics problem and scheme of its solution
Vitaliy Voytik
2013-08-19
In the article derived and checked differential equations that solve the problem of reconstructing the motion parameters of a rigid frame of reference if known proper acceleration and angular velocity of its origin as a function of proper time. These equations are based on the known transformation to an arbitrary rigid non-inertial reference frame, which generalizes the Lorentz transformation, takes into account the fact of his proper Thomas precession and form of the metric arbitrary frame of reference. Role this the problem in the physics is that all such frames which have the same characteristics will have the same properties.
Block model of western US kinematics from inversion of geodetic, fault slip, and earthquake data
NASA Astrophysics Data System (ADS)
McCaffrey, R.
2003-12-01
The active deformation of the southwestern US (30° to 41° N) is represented by a finite number of rotating, elastic spherical caps. Horizontal GPS velocities (1583), fault slip rates (94), and earthquake slip vectors (116) are inverted for block angular velocities, locking on block-bounding faults, and the rotation of individual GPS velocity fields relative to North America. GPS velocities are modeled as a combination of rigid block rotations and elastic strain rates resulting from interactions of adjacent blocks across bounding faults. The resulting Pacific - North America pole is indistinguishable from that of Beavan et al. (2001) and satisfies spreading in the Gulf of California and earthquake slip vectors in addition to GPS. The largest blocks, the Sierra Nevada - Great Valley and the eastern Basin and Range, show internal strain rates, after removing the elastic component, of only a few nanostrain/a, demonstrating long term approximately rigid behavior. Most fault slip data are satisfied except that the San Jacinto fault appears to be significantly faster than inferred from geology while the Coachella and San Bernardino segments of the San Andreas fault are slower, suggesting the San Andreas system is straightening out in Southern California. Vertical axis rotation rates for most blocks are clockwise and in magnitude more like the Pacific than North America. One exception is the eastern Basin and Range (242° E to 248° E) which rotates slowly anticlockwise about a pole offshore Baja.
Inverse Kinematics for Object Manipulation with Redundant Multi-fingered Robotic Hands
Vincenzo Lippiello; Fabio Ruggiero; Luigi Villani
Many applications of service robotics are based on object manipulation with multi-fingered mechanical hands, where the fingers\\u000a should operate in a coordinated fashion to achieve the desired motion of the manipulated object. In the absence of physical\\u000a interaction between the fingers and the object, simple motion synchronization shall be ensured. On the other hand, the execution\\u000a of object grasping or
Natural Resolution of Ill-Posedness of Inverse Kinematics for Redundant Robots Under Constraints
S. Arimoto; J.-H. Bae; H. Hashiguchi; R. Ozawa
2004-01-01
In order to enhance dexterity in execution of robot tasks, a\\u000aredundant number of degrees-of-freedom (DOF) is adopted for\\u000adesign of robotic mechanisms like robot arms and multi-fingered\\u000arobot hands. Associated with such redundancy in DOFs relative\\u000ato the number of physical variables necessary and sufficient\\u000afor description of a given task, an extra performance index\\u000ais introduced for controlling
A motion planner for a redundant mobile manipulator using the inverse kinematics
Gupta, Gautam Jagannath
2003-01-01
application in personal robotics as well as a service robot in various fields like factory automation, personal robotics, underwater exploration, surgery, space robotics and nuclear power plant. Furthermore, application of haptics interface for the mobde... manipulator can achieve tasks that are potentially dangerous, while avoidmg human presence in undesirable and hazardous surroundings. The basic expectations from a mobile manipulator, operating in a workspace, can be stated as follows: ~ Generate a...
Kinematic source models of earthquakes obtained by joint inversion of geodetic and seismic data
Heaton, Thomas H.
-double-couple component in Moment Tensor solution, is an interesting and well recorded event. This quake started the quakes are well recorded by TriNet station. The almost even distribution of moment on the westward #12
A biomimetic approach to inverse kinematics for a redundant robot arm
Artemiadis, Panagiotis
Redundant robots have received increased attention during the last decades, since they provide solutions to problems investigated for years in the robotic community, e.g. task-space tracking, obstacle avoidance etc. However, ...
To appear in ACM Trans. on Graphics (Proc. SIGGRAPH'04) Style-Based Inverse Kinematics
Anderson, Richard
Variable Model. The parameters of the model are all learned auto- matically; no manual tuning is required of computing the pose of a hu- man body from a set of constraints, is widely used in computer an- imation likely reach with his whole body, rather than keeping the rest of the body limp. In general
Inverse Kinematics Studies of Intermediate-Energy Reactions Relevant for SEE and Medical Problems
J. Aichelin; Ch. Bargholtz; J. Blomgren; A. Budzanowski; M. Chubarov; B. Czech; C. Ekström; L. Gerén; B. Jakobsson; A. Kolozhvari; O. Lozhkin; Yu. Murin; P. Nomokonov; N. Olsson; H. Persson; V. Pljuschev; I. Skwirczynska; H. H. K. Tang; P.-E. Tegnér; L. Westerberg; I. Zartova; M. Zubkov; Y. Watanabe
2005-01-01
The lack of systematic experimental checks on the intermediate-energy nuclear model simulations of heavily ionizing recoils from nucleon-nucleus collisions - critical inputs for the Single Event Effect analysis of microelectronics and dosimetry calculations including high-LET components in the cancer tumor radiation therapy - has been a primary motivation for a new experiment planned at the CELSIUS nuclear storage ring of
Outdoor Human Motion Capture using Inverse Kinematics and von Mises-Fisher Sampling
Eckmiller, Rolf
. In this paper, we introduce a novel hybrid HMC system that combines video input with sparse inertial sensor a novel sensor noise model to account for uncertainties based on the von Mises- Fisher distribution. Doing the search space [16, 25, 26, 27, 32]. On the downside, such priors impose cer- 1Corresponding author: pons@tnt
Calibration of parallel kinematic devices using sequential determination of kinematic parameters
JOKIEL JR.,BERNHARD; BIEG,LOTHAR F.; ZIEGERT,JOHN C.
2000-04-06
In PKM Machines, the Cartesian position and orientation of the tool point carried on the platform is obtained from a kinematic model of the particular machine. Accurate positioning of these machines relies on the accurate knowledge of the parameters of the kinematic model unique to the particular machine. The parameters in the kinematic model include the spatial locations of the joint centers on the machine base and moving platform, the initial strut lengths, and the strut displacements. The strut displacements are readily obtained from sensors on the machine. However, the remaining kinematic parameters (joint center locations, and initial strut lengths) are difficult to determine when these machines are in their fully assembled state. The size and complexity of these machines generally makes it difficult and somewhat undesirable to determine the remaining kinematic parameters by direct inspection such as in a coordinate measuring machine. In order for PKMs to be useful for precision positioning applications, techniques must be developed to quickly calibrate the machine by determining the kinematic parameters without disassembly of the machine. A number of authors have reported techniques for calibration of PKMs (Soons, Masory, Zhuang et. al., Ropponen). In two other papers, the authors have reported on work recently completed by the University of Florida and Sandia National Laboratories on calibration of PKMs, which describes a new technique to sequentially determine the kinematic parameters of an assembled parallel kinematic device. The technique described is intended to be used with a spatial coordinate measuring device such as a portable articulated CMM measuring arm (Romer, Faro, etc.), a Laser Ball Bar (LBB), or a laser tracker (SMX< API, etc.). The material to be presented is as follows: (1) methods to identify the kinematic parameters of 6--6 variant Stewart platform manipulators including joint center locations relative to the workable and spindle nose, and initial strut lengths, (2) and example of the application of the method, and (3) results from the application of the technique.
Inversions. Popular Lectures in Mathematics.
ERIC Educational Resources Information Center
Bakel'man, I. Ya
Inversions are transformations of geometric figures, under which straight lines may be mapped to circles, and conversely. The use of such mapping allows development of a unified method of solution for many of the problems of elementary geometry, especially those concerning constructions and "pencils" of curves. This book discusses the inversion…
Inverse Problems in Transport Theory
This paper is a review of the recent progress in the study of inverse problems for the transport equation in Rn ... k from the knowledge of A? In the time dependent case we study the inverse scattering problem as ...... Paris 320(1995), 947–952.
Modular theory of inverse systems
NASA Technical Reports Server (NTRS)
1979-01-01
The relationship between multivariable zeros and inverse systems was explored. A definition of zero module is given in such a way that it is basis independent. The existence of essential right and left inverses were established. The way in which the abstract zero module captured previous definitions of multivariable zeros is explained and examples are presented.
Inverse Spectral Problem Proof of Main Result
Stanhope, Liz
Inverse Spectral Problem Proof of Main Result Geodesics on Weighted Projective Spaces Zuoqin Wang of Main Result Inverse Spectral Geometry Main Result Inverse Spectral Geometry Manifold setting: (M, g Proof of Main Result Inverse Spectral Geometry Main Result Inverse Spectral Geometry Manifold setting
Methodological analysis of finite helical axis behavior in cervical kinematics.
Cescon, Corrado; Cattrysse, Erik; Barbero, Marco
2014-10-01
Although a far more stable approach compared to the six degrees of freedom analysis, the finite helical axis (FHA) struggles with interpretational difficulties among health professionals. The analysis of the 3D-motion axis has been used in clinical studies, but mostly limited to qualitative analysis. The aim of this study is to introduce a novel approach for the quantification of the FHA behavior and to investigate the effect of noise and angle intervals on the estimation of FHA parameters. A simulation of body movement has been performed introducing Gaussian noise on position and orientation of a virtual sensor showing linear relation between the simulated noise and the error in the corresponding parameter. FHA axis behavior was determined by calculating the intersection points of the FHA with a number of planes perpendicular to the FHA using the Convex Hull (CH) technique. The angle between the FHA and each of the IHA was also computed and its distribution was also analyzed. Input noise has an inversely proportional relationship with the angle steps of FHA estimation. The proposed FHA quantification approach can be useful to provide new approaches to researchers and to improve insight for the clinician in order to better understand joint kinematics. PMID:24916306
Kinematics of shot-geophone migration
Christiaan C. Stolk; Maarten V. de Hoop; William W. Symes
2009-01-01
Recent analysis and synthetic examples have shown that many prestack depth migration methods produce nonflat image gathers containing spurious events, even when provided with a kinematically correct migration velocity field, if this velocity field is highly refractive. This pathology occurs in all migration methods that produce partial images as independent migrations of data bins. Shot-geophone prestack depth migration is an
Observers for Kinematic Systems with Robert Mahony
Trumpf, Jochen
[1972]. Brockett's work was motivated by analytical mechanics and the study of mechanical systems, see kinematics onto the symmetry group and designing an observer for the lifted system. Two particular classes an error signal on the symmetry group using the group structure. We propose an observer structure
Tube pumice kinematics using neutron tomography
Asher Flaws; Kai-Uwe Hess; Donald B. Dingwell; Dominique Richard; Joan Marti
2010-01-01
Volume imaging using neutron computed tomography (NCT) offers a new window into rheological processes and their kinematic consequences. In the past, the penetration power of neutron scanning has been offset by its relatively poor resolution (order 1 mm). However, the recent development of new scintillators has improved this resolution by almost an order of magnitude to a voxel size of
Constrained tri-sphere kinematic positioning system
Viola, Robert J (Jackson, WY)
2010-12-14
A scalable and adaptable, six-degree-of-freedom, kinematic positioning system is described. The system can position objects supported on top of, or suspended from, jacks comprising constrained joints. The system is compatible with extreme low temperature or high vacuum environments. When constant adjustment is not required a removable motor unit is available.
Compound nucleus studies withy reverse kinematics
Moretto, L.G.
1985-06-01
Reverse kinematics reactions are used to demonstrate the compound nucleus origin of intermediate mass particles at low energies and the extension of the same mechanism at higher energies. No evidence has appeared in our energy range for liquid-vapor equilibrium or cold fragmentation mechanisms. 11 refs., 12 figs.
Large kinematic error propagation in revolute manipulators
Yunfeng Wang; Gregory S. Chirikjian
Understanding how errors propagate in serial revolute manipulators is important for developing better designs and planning algorithms, as well as understanding the practical limitations on accuracy of multi- link arms. In this paper we provide a systematic propagation method- ology and numerical example that illustrates how large kinematic errors propagate by convolution on the Euclidean motion group.
Navigation of Multiple Kinematically Constrained Robots
Savvas G. Loizou; Konstantinos J. Kyriakopoulos
2008-01-01
In this paper, we propose a methodology for implementing multirobot navigation-function-based controllers to mixed teams of holonomic and nonholonomic agents. A new nonsmooth backstepping controller is introduced for translating kinematic controllers to equivalent dynamic ones, while maintaining bounded velocity specifications. The derived backstepping controller is applied to a dynamic model of the mobile robots, yielding a globally asymptotically stable dynamic
Particle Acceleration and Kinematics in Solar Flares
Markus J. Aschwanden
2002-01-01
This book presents a synthesis of what we learned about particle acceleration and kinematics from recent solar flare observations with the Yohkoh, SoHO, TRACE, CGRO spacecraft and radio instruments over the last decade. It deals with the topology of magnetic reconnection regions, discusses the geometry, small-scale dynamics, and electromagnetic fields of acceleration region in solar flares, provides a systematic description
Kinematics of Stellar Populations in Poststarburst Galaxies
NASA Astrophysics Data System (ADS)
Hiner, Kyle D.; Canalizo, Gabriela
2015-01-01
Poststarburst galaxies host a population of early-type stars (A or F) but simultaneously lack indicators of ongoing star formation such as [O II] emission. Two distinct stellar populations have been identified in these systems: a young poststarburst population superimposed on an older host population. We present a study of nine poststarburst galaxies with the following objectives: (1) to investigate whether and how kinematical differences between the young and old populations of stars can be measured, and (2) to gain insight into the formation mechanism of the young population in these systems. We fit high signal-to-noise spectra with two independent populations in distinct spectral regions: the Balmer region, the Mg IB region, and the Ca triplet when available. We show that the kinematics of the two populations largely track one another if measured in the Balmer region with high signal-to-noise data. Results from examining the Faber-Jackson relation and the fundamental plane indicate that these objects are not kinematically disturbed relative to more evolved spheroids. A case study of the internal kinematics of one object in our sample shows it to be pressure supported and not rotationally dominated. Overall our results are consistent with merger-induced starburst scenarios where the young population is observed during the later stages of the merger.
Stellar Archeology : Chemical Compositions and Kinematics
NASA Astrophysics Data System (ADS)
Stringer, Bayard; Carney, Bruce
2011-10-01
The ?-CDM model of cosmology predicts a hierarchical formation mechanism of galaxies, with smaller units accreting to construct larger ones. The detection of merger events in external galaxies is well known, and the detection and analysis of merger remnants in the Milky Way is a key component in piecing together the history of our home galaxy. Statistical analyses of stellar kinematics in the solar neighborhood reveal much kinematic structure in the Galactic disk, but it is not readily apparent whether this structure is extragalactic or dynamical in origin. The most prominent structures are quickly identified as well known moving groups of stars such as the Hercules, Sirius, and Hyades stellar streams. Additionally, a subset of kinematically selected stars observed at McDonald Observatory are members of a stellar stream putatively identified by Amina Helmi as part of a merger remnant. A semi-automated, high resolution spectral analysis is applied to 504 F and G dwarf stars, and the results are amenable to Kolmogorov-Smirnov membership hypothesis testing. In all four cases, the kinematic streams have chemistries roughly consistent with the Galactic disk trends, although the statistical analyses suggest some subtle differences.
Kinematic Measurements from YouTube Videos
ERIC Educational Resources Information Center
Ruiz, Michael J.
2009-01-01
Video analysis of motion has been in use now for some time. However, some teachers may not have video equipment or may be looking for innovative ways to engage students with interesting applications at no cost. The recent advent of YouTube offers opportunities for students to measure kinematic properties of real-life events using their computers.…
A Nate on Dynamics and Kinematics*
generally. on event perception. Included under this heading is a growing body of work in social psychology and coordination as well as on skill acquisition and motor memory. Despite its importance to problems in human in the definition and use of "kinematics."1 However, the use of "kinetics" in the literature of mechanics
The Kinematics of Contact and Grasp
David J. Montana
1988-01-01
The kinematics of contact describe the motion of a point of contact over the surfaces of two contacting objects in response to a relative motion of these objects. Using concepts from differential geometry, I derive a set of equations, called the contact equations, that embody this relationship. I employ the contact equations to design the following applications to be executed
The Maiden Voyage of a Kinematics Robot
NASA Astrophysics Data System (ADS)
Greenwolfe, Matthew L.
2015-04-01
In a Montessori preschool classroom, students work independently on tasks that absorb their attention in part because the apparatus are carefully designed to make mistakes directly observable and limit exploration to one aspect or dimension. Control of error inheres in the apparatus itself, so that teacher intervention can be minimal.1 Inspired by this example, I created a robotic kinematics apparatus that also shapes the inquiry experience. Students program the robot by drawing kinematic graphs on a computer and then observe its motion. Exploration is at once limited to constant velocity and constant acceleration motion, yet open to complex multi-segment examples difficult to achieve in the lab in other ways. The robot precisely and reliably produces the motion described by the students' graphs, so that the apparatus itself provides immediate visual feedback about whether their understanding is correct as they are free to explore within the hard-coded limits. In particular, the kinematic robot enables hands-on study of multi-segment constant velocity situations, which lays a far stronger foundation for the study of accelerated motion. When correction is anonymous—just between one group of lab partners and their robot—students using the kinematic robot tend to flow right back to work because they view the correction as an integral part of the inquiry learning process. By contrast, when correction occurs by the teacher and/or in public (e.g., returning a graded assignment or pointing out student misconceptions during class), students all too often treat the event as the endpoint to inquiry. Furthermore, quantitative evidence shows a large gain from pre-test to post-test scores using the Test of Understanding Graphs in Kinematics (TUG-K).
Kinematic Optimization in Birds, Bats and Ornithopters
NASA Astrophysics Data System (ADS)
Reichert, Todd
Birds and bats employ a variety of advanced wing motions in the efficient production of thrust. The purpose of this thesis is to quantify the benefit of these advanced wing motions, determine the optimal theoretical wing kinematics for a given flight condition, and to develop a methodology for applying the results in the optimal design of flapping-wing aircraft (ornithopters). To this end, a medium-fidelity, combined aero-structural model has been developed that is capable of simulating the advanced kinematics seen in bird flight, as well as the highly non-linear structural deformations typical of high-aspect ratio wings. Five unique methods of thrust production observed in natural species have been isolated, quantified and thoroughly investigated for their dependence on Reynolds number, airfoil selection, frequency, amplitude and relative phasing. A gradient-based optimization algorithm has been employed to determined the wing kinematics that result in the minimum required power for a generalized aircraft or species in any given flight condition. In addition to the theoretical work, with the help of an extended team, the methodology was applied to the design and construction of the world's first successful human-powered ornithopter. The Snowbird Human-Powered Ornithopter, is used as an example aircraft to show how additional design constraints can pose limits on the optimal kinematics. The results show significant trends that give insight into the kinematic operation of natural species. The general result is that additional complexity, whether it be larger twisting deformations or advanced wing-folding mechanisms, allows for the possibility of more efficient flight. At its theoretical optimum, the efficiency of flapping-wings exceeds that of current rotors and propellers, although these efficiencies are quite difficult to achieve in practice.
Goal Directed Model Inversion: A Study of Dynamic Behavior
NASA Technical Reports Server (NTRS)
Colombano, Silvano P.; Compton, Michael; Raghavan, Bharathi; Lum, Henry, Jr. (Technical Monitor)
1994-01-01
Goal Directed Model Inversion (GDMI) is an algorithm designed to generalize supervised learning to the case where target outputs are not available to the learning system. The output of the learning system becomes the input to some external device or transformation, and only the output of this device or transformation can be compared to a desired target. The fundamental driving mechanism of GDMI is to learn from success. Given that a wrong outcome is achieved, one notes that the action that produced that outcome 0 "would have been right if the outcome had been the desired one." The algorithm then proceeds as follows: (1) store the action that produced the wrong outcome as a "target" (2) redefine the wrong outcome as a desired goal (3) submit the new desired goal to the system (4) compare the new action with the target action and modify the system by using a suitable algorithm for credit assignment (Back propagation in our example) (5) resubmit the original goal. Prior publications by our group in this area focused on demonstrating empirical results based on the inverse kinematic problem for a simulated robotic arm. In this paper we apply the inversion process to much simpler analytic functions in order to elucidate the dynamic behavior of the system and to determine the sensitivity of the learning process to various parameters. This understanding will be necessary for the acceptance of GDMI as a practical tool.
Bernsen, Erik, E-mail: e.bernsen@uu.n [Institute for Marine and Atmospheric research Utrecht, Utrecht University (Netherlands); Dijkstra, Henk A. [Institute for Marine and Atmospheric research Utrecht, Utrecht University (Netherlands); Thies, Jonas; Wubs, Fred W. [Johann Bernoulli Institute for Mathematics and Computer Science, Groningen University (Netherlands)
2010-10-20
In present-day forward time stepping ocean-climate models, capturing both the wind-driven and thermohaline components, a substantial amount of CPU time is needed in a so-called spin-up simulation to determine an equilibrium solution. In this paper, we present methodology based on Jacobian-Free Newton-Krylov methods to reduce the computational time for such a spin-up problem. We apply the method to an idealized configuration of a state-of-the-art ocean model, the Modular Ocean Model version 4 (MOM4). It is shown that a typical speed-up of a factor 10-25 with respect to the original MOM4 code can be achieved and that this speed-up increases with increasing horizontal resolution.
NASA Astrophysics Data System (ADS)
Bernsen, Erik; Dijkstra, Henk A.; Thies, Jonas; Wubs, Fred W.
2010-10-01
In present-day forward time stepping ocean-climate models, capturing both the wind-driven and thermohaline components, a substantial amount of CPU time is needed in a so-called spin-up simulation to determine an equilibrium solution. In this paper, we present methodology based on Jacobian-Free Newton-Krylov methods to reduce the computational time for such a spin-up problem. We apply the method to an idealized configuration of a state-of-the-art ocean model, the Modular Ocean Model version 4 (MOM4). It is shown that a typical speed-up of a factor 10-25 with respect to the original MOM4 code can be achieved and that this speed-up increases with increasing horizontal resolution.
Knupp, P.M.
1999-01-18
Structured mesh quality optimization methods are extended to optimization of unstructured triangular, quadrilateral, and mixed finite element meshes. N"ew interpretations of well-known nodally-bssed objective functions are made possible using matrices and matrix norms. The matrix perspective also suggests several new objective functions. Particularly significant is the interpretation of the Oddy metric and the Smoothness objective functions in terms of the condition number of the metric tensor and Jacobian matrix, respectively. Objective functions are grouped according to dimensionality to form weighted combinations. A simple unconstrained local optimum is computed using a modiiied N-ewton iteration. The optimization approach was implemented in the CUBIT mesh generation code and tested on several problems. Results were compared against several standard element-based quaIity measures to demonstrate that good mesh quality can be achieved with nodally-based objective functions.
3D kinematics using dual quaternions: theory and applications in neuroscience
Leclercq, Guillaume; Lefèvre, Philippe; Blohm, Gunnar
2013-01-01
In behavioral neuroscience, many experiments are developed in 1 or 2 spatial dimensions, but when scientists tackle problems in 3-dimensions (3D), they often face problems or new challenges. Results obtained for lower dimensions are not always extendable in 3D. In motor planning of eye, gaze or arm movements, or sensorimotor transformation problems, the 3D kinematics of external (stimuli) or internal (body parts) must often be considered: how to describe the 3D position and orientation of these objects and link them together? We describe how dual quaternions provide a convenient way to describe the 3D kinematics for position only (point transformation) or for combined position and orientation (through line transformation), easily modeling rotations, translations or screw motions or combinations of these. We also derive expressions for the velocities of points and lines as well as the transformation velocities. Then, we apply these tools to a motor planning task for manual tracking and to the modeling of forward and inverse kinematics of a seven-dof three-link arm to show the interest of dual quaternions as a tool to build models for these kinds of applications. PMID:23443667