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1

Real-Time Inverse Kinematics: The Return of the Jacobian 1 Real-Time Inverse Kinematics: The Return of the Jacobian  

E-print Network

domain that is tackled by inverse kinematics solvers was first formulated in the mechanical engineering of an inverse kinematics solver. However, because of their iterative nature, such methods can be slow. So far take a look at the Jacobian-based IK solver and techniques that allow this method to be used

Maddock, Steve

2

Using a Half-Jacobian for Real-Time Inverse Kinematics Michael Meredith & Steve Maddock  

E-print Network

, numerical techniques often form part of an inverse kinematics (IK) solver. However, because as efficiently as possible. In this paper we take a look at the Jacobian-based IK solver and techniques that allow this method to be used as an efficient real-time IK solver. We demonstrate how the half

Maddock, Steve

3

Inverse Jacobian Regulator With Gravity Compensation: Stability and Experiment  

Microsoft Academic Search

Task-space regulation of robot manipulators can be classified into two fundamental approaches, namely, transpose Jacobian regulation and inverse Jacobian regulation. In this paper, two inverse Jacobian regulators with gravity compensations are presented, and the stability problems are formulated and solved. It is shown that the inverse Jacobian systems can be stabilized, and there exists a region of attraction such that

Chien-Chern Cheah; Hwee Choo Liaw

2005-01-01

4

Inverse Jacobian based hybrid impedance control of redundant manipulators  

Microsoft Academic Search

This paper presents an efficient control scheme for compliant motion control of kinematically redundant manipulators and its evaluation using an experimental 7 degrees-of-freedom manipulator, REDIESTRO (a redundant dexterous isotropically enhanced, seven turning-pair robot). An inverse Jacobian based hybrid impedance control (IJ-HIC) scheme is proposed that provides a unified approach for combining compliant motion control, redundancy resolution, and user defined secondary

Mitesh Shah; R. V. Patel

2005-01-01

5

JFKengine: A Jacobian and Forward Kinematics Generator  

SciTech Connect

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.

Fischer, K.N.

2003-02-13

6

New insights into input relegation control for inverse kinematics of a redundant manipulator. Part 1, On the orthogonality of matrices B and J and comparison to the extended Jacobian method  

SciTech Connect

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.

Unseren, M.A.; Reister, D.B.

1995-07-01

7

Inversion without Explicit Jacobian Calculations in Electrical Impedance Tomography  

NASA Astrophysics Data System (ADS)

Electrical impedance tomography (EIT) is the inverse problem of finding the internal conductivity distribution of a medium given boundary electrical measurements performed via an electrode array onto its surface. Conventional inversion schemes adopt Tikhonov regularized Newton-type methods. Following a transport back-transport approach, we develop in this work an adjoint approach which allows reducing computational burden in enabling inversion without explicit Jacobian calculation. Forward and back-projection operators are defined from potential gradients, along with their efficient implementation. These derivations allow the transparent use of inversion algorithms. We first check the implementation of operators. We then evaluate how reconstructions perform on simulated noisy data using a preconditioned conjugate gradient. We eventually practice our inversion framework on experimental data acquired in vitro from a saline phantom.

Fouchard, A.; Bonnet, S.; Hervé, L.; David, O.

2014-10-01

8

Parallel processing architecture for computing inverse differential kinematic equations of the PUMA arm  

NASA Technical Reports Server (NTRS)

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.

Hsia, T. C.; Lu, G. Z.; Han, W. H.

1987-01-01

9

Development of the inverse Jacobian for the Kraft slave, and its use in force reflecting teleoperation  

Microsoft Academic Search

The development of the symbolic inverse of a manipulator Jacobian and its use in controlling the manipulator is discussed. The ease of symbolically inverting a matrix is directly related to the simplicity of the expressions in the matrix. Therefore, a general method for obtaining a simplified form of the Jacobian of a manipulator in any of the intermediate link frames

Dale E. Schinstock; Terry N. Faddis; R. B. Greenway

1993-01-01

10

Robust inverse kinematics using damped least squares with dynamic weighting  

NASA Technical Reports Server (NTRS)

This paper presents a general method for calculating the inverse kinematics with singularity and joint limit robustness for both redundant and non-redundant serial-link manipulators. Damped least squares inverse of the Jacobian is used with dynamic weighting matrices in approximating the solution. This reduces specific joint differential vectors. The algorithm gives an exact solution away from the singularities and joint limits, and an approximate solution at or near the singularities and/or joint limits. The procedure is here implemented for a six d.o.f. teleoperator and a well behaved slave manipulator resulted under teleoperational control.

Schinstock, D. E.; Faddis, T. N.; Greenway, R. B.

1994-01-01

11

Review of the damped least-squares inverse kinematics with experiments on an industrial robot manipulator  

Microsoft Academic Search

The goal of this paper is to present experimental results on the implementation of the damped least-squares method for the six-joint ABB IRb2000 industrial robot manipulator. A number of inverse kinematics schemes are reviewed which allow robot control through kinematic singularities. The basic scheme adopts a damped least-squares inverse of the manipulator Jacobian with a varying damping factor acting in

S. Chiaverini; B. Siciliano; O. Egeland

1994-01-01

12

Style-based inverse kinematics  

Microsoft Academic Search

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

Keith Grochow; Steven L. Martin; Aaron Hertzmann; Zoran Popovi?

2004-01-01

13

Closed-Loop Inverse Kinematics Algorithms for Redundant Spacecraft\\/Manipulator Systems  

Microsoft Academic Search

A solution is presented for the inverse kinematics of space manipulators mounted on a free-floating spacecraft. The approach is based on the generalized Jacobian notion that allows description of the reaction effects of manipulator motion on the spacecraft. Redundancy of the system with respect to the number of task variables for spacecraft attitude and manipulator end-effector pose is considered. Depending

Bruno Siciliano

1993-01-01

14

Iterative inverse kinematics with manipulator configuration control  

Microsoft Academic Search

A new method, termed the offset modification method (OM method), for solving the manipulator inverse kinematics problem is presented. The OM method works by modifying the link offset values of a manipulator until it is possible to derive closed-form inverse kinematics equations for the resulting manipulator (termed the model manipulator). This procedure allows one to derive a set of three

G. Z. Grudic; Peter D. Lawrence

1993-01-01

15

Introduction to Inverse Kinematics with Jacobian Transpose, Pseudoinverse and Damped  

E-print Network

). The mathematical foundations of these methods are presented, with an analysis based on the singular value methods [41, 34], quasi-Newton and conjugate gradient methods [43, 49, 15], and neural net and artificial intelligence methods [19, 27, 36, 38, 20, 22, 40, 16]. The present paper focuses on applications of IK

Chai, Jinxiang

16

Iterative inverse kinematics with manipulator configuration control  

SciTech Connect

A new method, termed the offset modification method (OM method), for solving the manipulator inverse kinematics problem is presented. The OM method works by modifying the link offset values of a manipulator until it is possible to derive closed-form inverse kinematics equations for the resulting manipulator (termed the model manipulator). This procedure allows one to derive a set of three nonlinear equations in three unknowns that, when numerically solved, give an inverse kinematics solution for the original manipulator. The OM method can be applied to manipulators with any number of degrees of freedom, as long as the manipulator satisfies a given set of conditions (Theorem 1). The OM method is tested on a 6-degree-of-freedom manipulator that has no known closed-form inverse kinematics equations. It is shown that the OM method is applicable to real-time manipulator control, can be used to guarantee convergence to a desired endpoint position and orientation (if it exists), and allows one to directly choose which inverse kinematics solution the algorithm will converge to (as specified in the model manipulator closed-form inverse kinematics equations). Applications of the method to other 6-DOF manipulator geometries and to redundant manipulators (i.e. greater than 6 DOF geometries) are discussed.

Grudic, G.Z.; Lawrence, P.D. [Univ. of British Columbia, Vancouver, British Columbia (Canada). Dept. of Electrical Engineering] [Univ. of British Columbia, Vancouver, British Columbia (Canada). Dept. of Electrical Engineering

1993-08-01

17

Inverse kinematic-based robot control  

NASA Technical Reports Server (NTRS)

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.

Wolovich, W. A.; Flueckiger, K. F.

1987-01-01

18

Fatigue Exploitation in an Inverse Kinematics Framework  

E-print Network

Chapter 5 Fatigue Exploitation in an Inverse Kinematics Framework 5.1 Introduction As was seen it. This technique allows an interactive manipulation of complex structures. We propose a fatigue in such a way that fatigue evolution over time can be exploited. Fatigue is then applied to postures

Rodríguez, Inmaculada

19

Wrist-Partitioned Inverse Kinematic Accelerations and Manipulator Dynamics  

E-print Network

An efficient algorithm is presented for the calculation of the inverse kinematic accelerations for a 6 degree-of-freedom manipulator with a spherical wrist. The inverse kinematic calculation is shown to work synergistically ...

Hollerbach, John M.

1983-04-01

20

Wrist-Partitioned, Inverse Kinematic Accelerations and Manipulator Dynamics  

Microsoft Academic Search

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,

John M. Hollerbach; Gideon Sahar

1983-01-01

21

Efficient calculation of Jacobian and adjoint vector products in the wave propagational inverse problem using automatic differentiation  

SciTech Connect

Wave propagational inverse problems arise in several applications including medical imaging and geophysical exploration. In these problems, one is interested in obtaining the parameters describing the medium from its response to excitations. The problems are characterized by their large size, and by the hyperbolic equation which models the physical phenomena. The inverse problems are often posed as a nonlinear data-fitting where the unknown parameters are found by minimizing the misfit between the predicted data and the actual data. In order to solve the problem numerically using a gradient-type approach, one must calculate the action of the Jacobian and its adjoint on a given vector. In this paper, the authors explore the use of automatic differentiation (AD) to develop codes that perform these calculations. They show that by exploiting structure at 2 scales, they can arrive at a very efficient code whose main components are produced by AD. In the first scale they exploit the time-stepping nature of the hyperbolic solver by using the Extended Jacobian framework. In the second (finer) scale, they exploit the finite difference stencil in order to make explicit use of the sparsity in the dependence of the output variables to the input variables. The main ideas in this work are illustrated with a simpler, one-dimensional version of the problem. Numerical results are given for both one- and two-dimensional problems. They present computational templates that can be used in conjunction with optimization packages to solve the inverse problem.

Coleman, T.F.; Santosa, F.; Verma, A.

2000-01-01

22

Forward and inverse kinematics of double universal joint robot wrists  

NASA Technical Reports Server (NTRS)

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.

Williams, Robert L., II

1991-01-01

23

Inverse kinematics problem in robotics using neural networks  

NASA Technical Reports Server (NTRS)

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.

Choi, Benjamin B.; Lawrence, Charles

1992-01-01

24

Learning Inverse Kinematics for Pose-Constraint Bimanual Movements  

Microsoft Academic Search

We present a neural network approach to learn inverse kine- matics of the humanoid robot ASIMO, where we focus on bi-manual tool use. The learning copes with both the highly redundant inverse kinematics of ASIMO and the additional arbitrary constraint imposed by the tool that couples both hands. We show that this complex kine- matics can be learned from few

Klaus Neumann; Matthias Rolf; Jochen J. Steil; Michael Gienger

2010-01-01

25

Computational neural learning formalisms for manipulator inverse kinematics  

NASA Technical Reports Server (NTRS)

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.

Gulati, Sandeep; Barhen, Jacob; Iyengar, S. Sitharama

1989-01-01

26

An adaptive inverse kinematics algorithm for robot manipulators  

NASA Technical Reports Server (NTRS)

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.

Colbaugh, R.; Glass, K.; Seraji, H.

1990-01-01

27

Production of Radioactive Nuclides in Inverse Reaction Kinematics  

E-print Network

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.

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

28

Inverse kinematic model of flexure-based microsurgical manipulator.  

PubMed

This paper presents the development of an inverse kinematic model for a flexure-based micromanipulator using a feedforward neural network. The manipulator is part of an active handheld instrument designed to cancel hand tremor during microsurgery. The manipulator is actuated using three piezoelectric stacks. Preliminary results yield a mean squared error of 5% of the total stack range of motion, and a maximum error of 14% of the total range of motion. PMID:17281570

Avedillo, Juan Garcia; Choi, David Y; Riviere, Cameron N

2005-01-01

29

Neuro-Fuzzy based Approach for Inverse Kinematics Solution of Industrial Robot Manipulators  

Microsoft Academic Search

Obtaining the joint variables that result in a desired position of the robot end-effector called as inverse kinematics is one of the most important problems in robot kinematics and control. As the complexity of robot increases, obtaining the inverse kinematics solution requires the solution of non linear equations having tran- scendental functions are difficult and computationally expensive. In this paper,

Srinivasan Alavandar; M. J. Nigam

2008-01-01

30

Learning inverse kinematics: reduced sampling through decomposition into virtual robots.  

PubMed

We propose a technique to speedup the learning of the inverse kinematics of a robot manipulator by decomposing it into two or more virtual robot arms. Unlike previous decomposition approaches, this one does not place any requirement on the robot architecture, and thus, it is completely general. Parametrized self-organizing maps are particularly adequate for this type of learning, and permit comparing results directly obtained and through the decomposition. Experimentation shows that time reductions of up to two orders of magnitude are easily attained. PMID:19022727

de Angulo, Vicente Ruiz; Torras, Carme

2008-12-01

31

A study on estimation of planar gait kinematics using minimal inertial measurement units and inverse kinematics.  

PubMed

This paper describes a preliminary study of using four inertial measurement units (IMUs) attached to the heel and pelvis to estimate the joint angles of normal subjects during walking. The IMU, consisting of a 3-D accelerometer and gyroscope, is used to estimate the planar displacement of the heel and pelvis and the angular change of heel in one gait cycle. We then model the gait as a planar 3R serial chain and solve its inverse kinematics by using such information. The results are validated by comparing the estimated joint angles of lower limbs (i.e. hip, knee and ankle angles) with an optical motion capture system. This study can benefit the future research on conducting complete lower limbs kinematics analysis with minimal and unobtrusive wearable sensors. PMID:25571585

Hu, Xinyao; Soh, Gim Song

2014-01-01

32

Kinematic Waveform Inversion: Application in Southwest Iberia Seismicity  

NASA Astrophysics Data System (ADS)

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.

Domingues, A. L.; Custodio, S.; Cesca, S.

2011-12-01

33

Advanced control schemes and kinematic analysis for a kinematically redundant 7 DOF manipulator  

NASA Technical Reports Server (NTRS)

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.

Nguyen, Charles C.; Zhou, Zhen-Lei

1990-01-01

34

Production of light radioactive ion beams (RIB) using inverse kinematics  

NASA Astrophysics Data System (ADS)

At Nuclear Science Centre (NSC), New Delhi, we have implemented a facility to produce low energy light radioactive ion beams (RIBs) using (p,n) type of reactions in inverse kinematics. For this purpose primary beams from the 15-UD Pelletron accelerator impinged on a thin polypropylene foil mounted on a rotating/linearly moving target assembly. For efficiently separating the secondary beam from primary beam, the existing recoil mass spectrometer (RMS) HIRA was operated with new ion optics. Suitable hardware modifications were also made. Using this facility, we have extracted a 7Be beam of purity better than 99% and spot-size ˜4 mm in diameter. This 7Be beam has been utilized in a variety of experiments in the energy range of 15-22 MeV. Typical beam parameters are: intensity 10 4 pps, angular spread ±30 mrad and energy spread ±0.5 MeV. Development of appropriate detector setup/target arrangement were also made to perform these experiments. In this paper, we describe the implementation of this project.

Das, J. J.; Sugathan, P.; Madhavan, N.; Madhusudhana Rao, P. V.; Jhingan, A.; Varughese, T.; Barua, S.; Nath, S.; Sinha, A. K.; Kumar, B.; Zacharias, J.

2005-12-01

35

Inelastic Proton Scattering on 21Na in Inverse Kinematics  

NASA Astrophysics Data System (ADS)

R.A.E. Austin, R. Kanungo, S. Reeve, Saint Mary's University; D.G. Jenkins, C.Aa.Diget, A. Robinson, A.G. Tuff, O. Roberts, University of York, UK; P.J. Woods, T. Davinson, G. J. Lotay, University of Edinburgh; C.-Y. Wu, Lawrence Livermore National Laboratory; H. Al Falou, G.C. Ball, M. Djongolov, A. Garnsworthy, G. Hackman, J.N. Orce, C.J. Pearson, S. Triambak, S.J. Williams, TRIUMF; C. Andreiou, D.S. Cross, N. Galinski, R. Kshetri, Simon Fraser University; C. Sumithrarachchi, M.A. Schumaker, University of Guelph; M.P. Jones, S.V. Rigby, University of Liverpool; D. Cline, A. Hayes, University of Rochester; T.E. Drake, University of Toronto; We describe an experiment and associated technique [1] to measure resonances of interest in astrophysical reactions. At the TRIUMF ISAC-II radioactive beam accelerator facility in Canada, particles inelastically scattered in inverse kinematics are detected with Bambino, a ?E-E silicon telescope spanning 15-40 degrees in the lab. We use the TIGRESS to detect gamma rays in coincidence with the charged particles to cleanly select inelastic scattering events. We measured resonances above the alpha threshold in ^22Mg of relevance to the rate of break-out from the hot-CNO cycle via the reaction ^ 18Ne(?,p)^21Na. [1] PJ Woods et al. Rex-ISOLDE proposal 424 Cern (2003).

Austin, Roby

2009-10-01

36

A Closed Form Solution for Inverse Kinematics of Robot Manipulator with Redundancy  

E-print Network

A closed form equation for inverse kinematics of manipulator with redundancy is derived, using the Lagrangian multiplier method. The proposed equation is proved to provide the exact equilibrium state for the resolved ...

Chang, Pyung H.

1986-03-01

37

Artist-Directed Inverse-Kinematics Using Radial Basis Function Interpolation  

Microsoft Academic Search

One of the most common tasks in computer animation is inverse-kinematics, or determining a joint configuration required to place a particular part of an articulated character at a particular location in global space. Inverse- kinematics is required at design-time to assist artists using commercial 3D animation packages, for motion capture analysis, and for run-time applications such as games. We present

Charles F. Rose III; Peter-pike J. Sloan; Michael F. Cohen

2001-01-01

38

Inverse kinematic solution for near-simple robots and its application to robot calibration  

NASA Technical Reports Server (NTRS)

This paper provides an inverse kinematic solution for a class of robot manipulators called near-simple manipulators. The kinematics of these manipulators differ from those of simple-robots by small parameter variations. Although most robots are by design simple, in practice, due to manufacturing tolerances, every robot is near-simple. The method in this paper gives an approximate inverse kinematics solution for real time applications based on the nominal solution for these robots. The validity of the results are tested both by a simulation study and by applying the algorithm to a PUMA robot.

Hayati, Samad A.; Roston, Gerald P.

1986-01-01

39

A behavior-based inverse kinematics algorithm to predict arm prehension postures for computer-aided ergonomic evaluation  

Microsoft Academic Search

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

Xuguang Wang

1999-01-01

40

Inverse kinematic analysis of parallel supporting structure based on Rodrigues parameters  

NASA Astrophysics Data System (ADS)

A new method to describe the position-stance of parallel supporting structure is proposed based on Rodrigues theory. Comparing with others methods, the kinematic model with Rodrigues parameters has the advantages including least computational parameters, no trigonometric function calculation and convenient real-time control. The model of the inverse kinematics is established and the inverse solutions of the position-stance are obtained by analyzing the topologic structure of the parallel supporting structure with 3-RPS limb. By analyzing the vectors of the manipulator, the velocity and acceleration models of moving platform, limbs and end-effector arw deduced. According to the designed kinematic track, it is convenient to control accurately the supporting structure by the inverse kinematic model of the mechanism.

Cheng, Gang; Ge, Shi-Rong; Wan, Yong-Jian

2009-05-01

41

Manipulator inverse kinematics control based on particle swarm optimization neural network  

NASA Astrophysics Data System (ADS)

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.

Wen, Xiulan; Sheng, Danghong; Guo, Jing

2008-10-01

42

Development of ORRUBA: A Silicon Array for the Measurement of Transfer Reactions in Inverse Kinematics  

SciTech Connect

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.

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

43

Kinematic earthquake rupture inversion in the frequency domain  

NASA Astrophysics Data System (ADS)

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.

Fan, Wenyuan; Shearer, Peter M.; Gerstoft, Peter

2014-11-01

44

A statistical kinematic source inversion approach based on the QUESO library for uncertainty quantification and prediction  

NASA Astrophysics Data System (ADS)

Seismic, often augmented with geodetic data, are frequently used to invert for the spatio-temporal evolution of slip along a rupture plane. The resulting images of the slip evolution for a single event, inferred by different research teams, often vary distinctly, depending on the adopted inversion approach and rupture model parameterization. This observation raises the question, which of the provided kinematic source inversion solutions is most reliable and most robust, and — more generally — how accurate are fault parameterization and solution predictions? These issues are not included in "standard" source inversion approaches. Here, we present a statistical inversion approach to constrain kinematic rupture parameters from teleseismic body waves. The approach is based a) on a forward-modeling scheme that computes synthetic (body-)waves for a given kinematic rupture model, and b) on the QUESO (Quantification of Uncertainty for Estimation, Simulation, and Optimization) library that uses MCMC algorithms and Bayes theorem for sample selection. We present Bayesian inversions for rupture parameters in synthetic earthquakes (i.e. for which the exact rupture history is known) in an attempt to identify the cross-over at which further model discretization (spatial and temporal resolution of the parameter space) is no longer attributed to a decreasing misfit. Identification of this cross-over is of importance as it reveals the resolution power of the studied data set (i.e. teleseismic body waves), enabling one to constrain kinematic earthquake rupture histories of real earthquakes at a resolution that is supported by data. In addition, the Bayesian approach allows for mapping complete posterior probability density functions of the desired kinematic source parameters, thus enabling us to rigorously assess the uncertainties in earthquake source inversions.

Zielke, Olaf; McDougall, Damon; Mai, Martin; Babuska, Ivo

2014-05-01

45

To appear in ACM Trans. on Graphics (Proc. SIGGRAPH'04) Style-Based Inverse Kinematics  

E-print Network

styles. Our style-based IK can replace conventional IK, wherever it is used in computer animation: Character animation, Inverse Kinematics, motion style, machine learning, Gaussian Processes, non, the likelihood of poses depends on the body shape and style of the individual person, and designing

Washington at Seattle, University of

46

Inverse Kinematics for a Point-Foot Quadruped Robot with Dynamic Redundancy Resolution  

E-print Network

Inverse Kinematics for a Point-Foot Quadruped Robot with Dynamic Redundancy Resolution Alexander of center of mass and swing leg trajectories in LittleDog, a point-foot quadruped robot. It is not clear how of actuated joint angles because point-foot walkers have no direct actuation between the feet and the ground

Tedrake, Russ

47

Direct and Inverse Kinematics of a Novel Tip-Tilt-Piston Parallel Manipulator  

NASA Technical Reports Server (NTRS)

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 16 assembly configurations for the manipulator. In addition, it is shown that the 16 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.

Tahmasebi, Farhad

2004-01-01

48

Cortical network modeling for inverse kinematic computation of an anthropomorphic finger.  

PubMed

The performance of reaching movements to visual targets requires complex kinematic mechanisms such as redundant, multijointed, anthropomorphic actuators and thus is a difficult problem since the relationship between sensory and motor coordinates is highly nonlinear. In this article, we present a neural model able to learn the inverse kinematics of a simulated anthropomorphic robot finger (ShadowHand™ finger) having four degrees of freedom while performing 3D reaching movements. The results revealed that this neural model was able to control accurately and robustly the finger when performing single 3D reaching movements as well as more complex patterns of motion while generating kinematics comparable to those observed in human. The long term goal of this research is to design a bio-mimetic controller providing adaptive, robust and flexible control of dexterous robotic/prosthetics hands. PMID:22256258

Gentili, Rodolphe J; Oh, Hyuk; Molina, Javier; Contreras-Vidal, José L

2011-01-01

49

Neutron Capture Surrogate Reaction on 75As in Inverse Kinematics Using (d,p(gamma))  

SciTech Connect

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.

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

50

Thick-target yields of radioactive targets deduced from inverse kinematics  

E-print Network

The thick-target yield (TTY) of long-lived fission products (LLFP) is an essential quantity and represents basic data for transmutation. In order to evaluate TTY on radioactive targets including LLFP, we suggest a conversion method from inverse kinematics corresponding to the reaction of radioactive beams on stable targets. We demonstrate the method to deduce the TTY from inverse kinematics derived from the theoretical definition. This method is highly applicable in reactions at the energy per nucleon \\epsilon > 20 MeV/A as practically confirmed by the simulation of the SRIM2008 code. In this paper, we apply the method to the natCu(12C,X)24Na reaction to confirm availability. In addition, it is applied to the 137Cs + 12C reaction to reduce 137Cs and to suggest a TTY measurement of the 137Cs induced reaction on a thick 12C target.

Masayuki Aikawa; Shuichiro Ebata; Shotaro Imai

2014-11-25

51

Cortex Inspired Model for Inverse Kinematics Computation for a Humanoid Robotic Finger  

PubMed Central

In order to approach human hand performance levels, artificial anthropomorphic hands/fingers have increasingly incorporated human biomechanical features. However, the performance of finger reaching movements to visual targets involving the complex kinematics of multi-jointed, anthropomorphic actuators is a difficult problem. This is because the relationship between sensory and motor coordinates is highly nonlinear, and also often includes mechanical coupling of the two last joints. Recently, we developed a cortical model that learns the inverse kinematics of a simulated anthropomorphic finger. Here, we expand this previous work by assessing if this cortical model is able to learn the inverse kinematics for an actual anthropomorphic humanoid finger having its two last joints coupled and controlled by pneumatic muscles. The findings revealed that single 3D reaching movements, as well as more complex patterns of motion of the humanoid finger, were accurately and robustly performed by this cortical model while producing kinematics comparable to those of humans. This work contributes to the development of a bioinspired controller providing adaptive, robust and flexible control of dexterous robotic and prosthetic hands. PMID:23366569

Gentili, Rodolphe J.; Oh, Hyuk; Molina, Javier; Reggia, James A.; Contreras-Vidal, José L.

2013-01-01

52

Fault Framework and Kinematic Evolution of Mesozoic Intraforeland Inversion Structures, Central Neuquén Basin, Argentina  

NASA Astrophysics Data System (ADS)

Natural examples of basin inversion may be best analyzed using 3D seismic data. Detailed documentation of the complex fault framework and construction of curvature maps for fracture prediction may only be possible with the 3D seismic coverage over inversion structures. Whereas analog models show lateral variations in structural style and stratigraphic development during inversion, similar relationships have rarely been documented in natural inversion structures, which limits our understanding of the three-dimensional aspects of these features. A 3D seismic-reflection and borehole data set over a series of Mesozoic inversion structures in the Neuquén Basin of west-central Argentina was used to characterize, in full 3D, the structural and stratigraphic relationships associated with tectonic inversion structures that formed in this retroarc foreland setting. High-resolution time-structure maps, 3D visualization, seismic-attribute analysis (variance, time-dip, and amplitude), and structural restorations allowed the documentation of structural styles, fault linkage and propagation patterns, fold development, syn-inversion growth stratal patterns, and kinematic evolution. Inversion structures in the study area are characterized by two main fault systems. A deep fault system (that originally affected basement rocks and syn-rift strata during rifting) was selectively reactivated during inversion. Larger faults that formed during previous extension were preferentially reverse-reactivated during inversion, whereas smaller syn-rift faults were typically not reactivated. A shallower fault system, comprised of syn-inversion normal faults, formed at high angles to the reactivated, deep fault that generally bound the southern flank of the inversion structures. The shallower faults affected both post-rift and syn-inversion strata. The map patterns, location, and kinematic history of the shallower faults indicate that the hangingwall of the structure expanded during uplift and internally deformed as it accommodated to the shape of the curved footwall during oblique inversion. Similar styles of faulting are not reported in analog-model studies. Within the post-rift and younger section, a single through-going but curved fault defines the southern boundary of the inversion structures. This single fault changes into a series of fault segments, separated by accommodation zones, at depth. Fault systems in former syn-rift accommodation zones became linked into a through-going reverse fault during inversion. Folding and internal deformation were probably the dominant mechanisms that accommodated contraction during early and late stages of inversion. Initial fault lock-up at shallower stratigraphic and structural levels was due to the steep dips of the master fault at these levels, a condition that is not conducive to reactivation. During late stages of inversion, thick overburden inhibited further fault displacement and folding became the main mechanism for accommodating the contraction. Observations from this study suggest the need to incorporate more complex deformation scenarios, such as oblique inversion of curved (in plan view) faults and various hangingwall block deformation mechanisms, into scaled-model experiments.

Grimaldi, G. O.

2005-12-01

53

Inverse kinematic and forward dynamic models of the 2002 Denali fault earthquake, Alaska  

USGS Publications Warehouse

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.

Oglesby, D.D.; Dreger, Douglas S.; Harris, R.A.; Ratchkovski, N.; Hansen, R.

2004-01-01

54

Kinematic control of redundant free-floating robotic systems  

Microsoft Academic Search

This paper is aimed at presenting solution algorithms to the inverse kinematics of a space manipulator mounted on a free-floating spacecraft. The reaction effects of the manipulator's motion on the spacecraft are taken into account by means of the so-called generalized Jacobian. Redundancy of the system with respect to the number of task variables for spacecraft attitude and manipulator end-effector

Fabrizio Caccavale; Bruno Siciliano

2001-01-01

55

Alpha-particle capture reactions in inverse kinematics relevant to p-process nucleosynthesis  

SciTech Connect

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.

Ujic, P.; Oliveira Santos, F. de; Stodel, Ch.; Saint-Laurent, M.-G.; Kamalou, O.; Amthor, M. A.; Grevy, S.; Caceres, L. [GANIL, Bd. Henri Becquerel, Caen (France); Lagoyannis, A.; Mertzimekis, T. J.; Harissopulos, S.; Demetriou, P. [Institute of Nuclear Physics, NCSR 'Demokritos', Aghia Paraskevi, Athens (Greece); Perrot, L. [CNRS/IN2P3, IPN Orsay (France); Lefebvre-Schuhl, A. [CSNSM, Orsay (France); Spyrou, A. [NSCL/MSU, East Lansing, Michigan (United States); Koivisto, H.; Laitinen, M.; Uusitalo, J.; Julin, R. [Department of Physics, University of Jyvaeskylae (Finland)

2011-10-28

56

An inverse kinematics algorithm for a highly redundant variable-geometry-truss manipulator  

NASA Technical Reports Server (NTRS)

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.

Naccarato, Frank; Hughes, Peter

1989-01-01

57

Minor actinide fission induced by multi-nucleon transfer reaction in inverse kinematics  

NASA Astrophysics Data System (ADS)

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.

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

58

Kinematic inversion of physically plausible earthquake source models obtained from Dynamic Rupture Simulations  

NASA Astrophysics Data System (ADS)

A common approach to investigate earthquake physics consists of producing kinematic source models from the inversion of seismic records jointly with geodetic data. The regularization of the inversion requires some assumptions to restrict the range of possible models. Here, we evaluate to what extent physically plausible models are reliably restituted in spite these restrictions. More precisely we study which characteristics of ruptures, such as rupture velocity, slip distribution, and rise time can be reliably determined from the inversion of near-field data. We use a standard inversion scheme which assumes a rupture front propagating away from the hypocenter with a simple cosine slip-time function, and searches for solutions with minimum roughness [Ji et al, 2002]. To provide inversions with physically plausible sources, we generate several earthquake scenarios using 3D spectral-element simulations of dynamic rupture (Kaneko et al., 2008). The assumed model contains a planar fault in an elastic half-space. The fault is governed by rate and state friction, with a velocity-weakening region surrounded by slip-inhibiting velocity-strengthening regions. The fault properties are varied to obtain scenarios with different slip distributions and local slip durations, leading to pulse and crack-like ruptures. For the inversion, strike, dip, average rake, velocity model and the hypocenter are given, and we search for slip evolution that best fits strong-motion and GPS data at simulated stations, without a priori knowledge of moment, smoothness, rupture velocity, or slip distribution. The comparison with the input model is done only after the best-fit model is chosen among various constraint inversions. Our preliminary results show that, overall, rupture velocity and slip distribution are well- determined. Since we assume a single cosine for the slip-time function, both crack-like and pulse-like ruptures appear as pulses in the inverted models, but crack-like ruptures have larger spatial extent at each moment. The difference between the two kinds of ruptures is thus still observable. However, the slip history at a specific point on the fault cannot be obtained accurately due to the assumed shape of the slip time function. This is probably the major drawback of these inversion procedures. Our current work is therefore directed towards implementing different slip-time functions to allow a wider range of possible behavior without adding complexity to the inversion.

Konca, A.; Kaneko, Y.; Lapusta, N.; Avouac, J.

2008-12-01

59

On the structure of the inverse kinematics map of a fragment of protein backbone.  

PubMed

Loop closure in proteins requires computing the values of the inverse kinematics (IK) map for a backbone fragment with 2n > or = 6 torsional degrees of freedom (dofs). It occurs in a variety of contexts, e.g., structure determination from electron-density maps, loop insertion in homology-based structure prediction, backbone tweaking for protein energy minimization, and the study of protein mobility in folded states. The first part of this paper analyzes the global structure of the IK map for a fragment of protein backbone with 6 torsional dofs for a slightly idealized kinematic model, called the canonical model. This model, which assumes that every two consecutive torsional bonds C(alpha)--C and N--C(alpha) are exactly parallel, makes it possible to separately compute the inverse orientation map and the inverse position map. The singularities of both maps and their images, the critical sets, respectively, decompose SO(3) x R(3) into open regions where the number of IK solutions is constant. This decomposition leads to a constructive proof of the existence of a region in R(3) x SO(3) where the IK of the 6-dof fragment attains its theoretical maximum of 16 solutions. The second part of this paper extends this analysis to study fragments with more than 6 torsional dofs. It describes an efficient recursive algorithm to sample IK solutions for such fragments, by identifying the feasible range of each successive torsional dof. A numerical homotopy algorithm is then used to deform the IK solutions for a canonical fragment into solutions for a noncanonical fragment. Computational results for fragments ranging from 8 to 30 dofs are presented. PMID:17542001

Milgram, R J; Liu, Guanfeng; Latombe, J C

2008-01-15

60

Analytical and semi-analytical inverse kinematics of SSRMS-type manipulators with single joint locked failure  

NASA Astrophysics Data System (ADS)

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.

Xu, Wenfu; She, Yu; Xu, Yangsheng

2014-12-01

61

Optimization methods for hyper-redundant robots' inverse kinematics in biomedical applications  

NASA Astrophysics Data System (ADS)

The present work describes and compares several approaches applied to compute the inverse kinematics of a ten degrees of freedom hyper-redundant robot. The proposed approaches are based on an exhaustive method and several error-optimization algorithms. The algorithms' performance was evaluated based on two criteria: computational processing time and final actuator positioning error. The results obtained show that for a small number of modules (less or equal to four), the exhaustive method provides the best problem solution: acceptable computational processing time as well as minimum error. However, for larger number of modules, the error-optimization approach has far better performance regarding the error to processing time ratio. The mentioned hyper-redundant robot was projected to be used in biomedical applications.

Espinoza, Mario Sáenz; Pereira, Ana I.; Gonçalves, José

2012-09-01

62

A neutron spectrometer for studying giant resonances with (p,n) reactions in inverse kinematics  

NASA Astrophysics Data System (ADS)

A neutron spectrometer, the European Low-Energy Neutron Spectrometer (ELENS), has been constructed to study exotic nuclei in inverse-kinematics experiments. The spectrometer, which consists of plastic scintillator bars, can be operated in the neutron energy range of 100 keV-10 MeV. The neutron energy is determined using the time-of-flight technique, while the position of the neutron detection is deduced from the time-difference information from photomultipliers attached to both ends of each bar. A novel wrapping method has been developed for the plastic scintillators. The array has a larger than 25% detection efficiency for neutrons of approximately 500 keV in kinetic energy and an angular resolution of less than 1°. Details of the design, construction and experimental tests of the spectrometer will be presented.

Stuhl, L.; Krasznahorkay, A.; Csatlós, M.; Algora, A.; Gulyás, J.; Kalinka, G.; Timár, J.; Kalantar-Nayestanaki, N.; Rigollet, C.; Bagchi, S.; Najafi, M. A.

2014-02-01

63

Kinematic Slip Model for 12 May 2008 Wenchuan-Beichuan Mw 7.9 Earthquake from Joint Inversion of ALOS, Envisat, and Teleseismic Data  

NASA Technical Reports Server (NTRS)

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).

Fielding, Eric; Sladen, Anthony; Avouac, Jean-Philippe; Li, Zhenhong; Ryder, Isabelle; Burgmann, Roland

2008-01-01

64

Block kinematics of the PacificNorth America plate boundary in the southwestern United States from inversion of GPS,  

E-print Network

Block kinematics of the Pacific­­North America plate boundary in the southwestern United States­North America plate boundary in the southwestern United States from inversion of GPS, seismological of the southwestern United States (30°­41°N) is represented by a finite number of rotating, elastic-plastic spherical

McCaffrey, Robert

65

Homological versus algebraic equivalence in a jacobian.  

PubMed

Let Z be an algebraic p cycle homologous to zero in an algebraic complex manifold V. Associated to Z is a linear function nu on holomorphic (2p + 1)-forms on V, modulo periods, that vanishes if Z is algebraically equivalent to zero in V. I give a formula for nu for the case of V the jacobian of an algebraic curve C and Z=C - C' (C' = "inverse" of C') in terms of iterated integrals of holomorphic 1-forms on C. If C is the degree 4 Fermat curve, I use this formula to show that C - C' is not algebraically equivalent to zero. PMID:16593281

Harris, B

1983-02-01

66

Homological versus algebraic equivalence in a jacobian  

PubMed Central

Let Z be an algebraic p cycle homologous to zero in an algebraic complex manifold V. Associated to Z is a linear function ? on holomorphic (2p + 1)-forms on V, modulo periods, that vanishes if Z is algebraically equivalent to zero in V. I give a formula for ? for the case of V the jacobian of an algebraic curve C and Z=C - C? (C? = “inverse” of C?) in terms of iterated integrals of holomorphic 1-forms on C. If C is the degree 4 Fermat curve, I use this formula to show that C - C? is not algebraically equivalent to zero. PMID:16593281

Harris, Bruno

1983-01-01

67

Derivation of three closed loop kinematic velocity models using normalized quaternion feedback for an autonomous redundant manipulator with application to inverse kinematics  

SciTech Connect

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.

Unseren, M.A.

1993-04-01

68

More power to kinematic earthquake source inversions: With new tools from mismodelling to uncertainties  

NASA Astrophysics Data System (ADS)

The notorious discrepancies among finite fault slip inversion results have attracted much attention over the last years. In consequence, much effort has been put into methods to improve the robustness of such inversions and to quantify uncertainties on results. The techniques exploited include controlling the smoothness of the inferred slip distribution, reducing dimensionality of parameter-space, propagation of observational errors through Bayesian inference, Monte-Carlo modelling and bootstrapping. The difficulties in earthquake finite source parameter estimation arise from three distinct origins: (1) observational errors, (2) the (in)ability of the earthquake source model to represent nature, and (3) mismodelling of synthetic seismograms. While observational errors can often be formally included in the source parameter estimation process, the latter two are much harder to to handle. Appropriateness of the source model (2) is hard to achieve because more realistic models require more model parameters and quickly lead to underdetermined systems. Mismodelling of synthetic seismograms (3) has not been investigated much, probably because the technical effort to deal with it is usually high (because forward modelling may have to be repeated for many earth model variations). In this presentation, we will show that freely available precomputed Green's functions for ensembles of different earth models will make such investigations feasible for routine practice. We will illustrate this with a synthetic test case of a regional kinematic source parameter optimization. The presented work is closely related with the development of a new open source Python toolbox for the handling of precomputed Green's functions and for synthetic seismogram generation (http://emolch.github.io/pyrocko/gf). Ultimately, we would like to launch a community driven open access Green's function sharing platform and web services for synthetic seismogram and test scenario generation (http://kinherd.org/).

Heimann, Sebastian; Sudhaus, Henriette; Wang, Rongjiang; Cesca, Simone; Dahm, Torsten

2014-05-01

69

Design of human-like posture prediction for inverse kinematic posture control of a humanoid robot  

E-print Network

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 ...

Thomann, Derik (Derik S.)

2005-01-01

70

The double universal joint wrist on a manipulator: Solution of inverse position kinematics and singularity analysis  

NASA Technical Reports Server (NTRS)

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.

Williams, Robert L., III

1992-01-01

71

Gravity modeling: the Jacobian function and its approximation  

NASA Astrophysics Data System (ADS)

In mathematics, the elements of a Jacobian matrix are the first-order partial derivatives of a scalar function or a vector function with respect to another vector. In inversion theory of geophysics the elements of a Jacobian matrix are a measure of the change of the output signal caused by a local perturbation of a parameter of a given (Earth) model. The elements of a Jacobian matrix can be determined from the general Jacobian function. In gravity modeling this function consists of the "geometrical part" (related to the relative location in 3D of a field point with respect to the source element) and the "source-strength part" (related to the change of mass density of the source element). The explicit (functional) expressions for the Jacobian function can be quite complicated and depend both on the coordinates used (Cartesian, spherical, ellipsoidal) and on the mathematical parametrization of the source (e.g. the homogenous rectangular prism). In practice, and irrespective of the exact expression for the Jacobian function, its value on a computer will always be rounded to a finite number of digits. In fact, in using the exact formulas such finite representation may cause numerical instabilities. If the Jacobian function is smooth enough, it is an advantage to approximate it by a simpler function, e.g. a piecewise-polynomial, which numerically is more robust than the exact formulas and which is more suitable for the subsequent integration. In our contribution we include a whole family of the Jacobian functions which are associated with all the partial derivatives of the gravitational potential of order 0 to 2, i.e. including all the elements of the gravity gradient tensor. The quality of the support points for the subsequent polynomial approximation of the Jacobian function is ensured by using the exact prism formulas in quadruple precision. We will show some first results. Also, we will discuss how such approximated Jacobian functions can be used for large scale modeling so that the source model can (almost) be of unlimited degree of detail and where the modeling can be conducted without a substantial increase in the computational task. The main idea here is to integrate instead of summing up the partial contributions from the discrete source elements.

Strykowski, G.; Lauritsen, N. L. B.

2012-04-01

72

Adaptive Jacobian Motion and Force Tracking Control for Constrained Robots with Uncertainties  

Microsoft Academic Search

Most research so far on motion and force tracking control of robots has assumed that the kinematics and dynamics are exactly known. In this paper, we propose an adaptive Jacobian controller for motion and force tracking with uncertainties in kinematics and dynamics. It is shown that the robot end-effector can track the desired position and force trajectories with the uncertain

Chien-chern Cheah; Yu Zhao; Jean-jacques E. Slotine

2006-01-01

73

Estimating periodic organ motions based on inverse kinematics using tetrahedron mesh registration  

NASA Astrophysics Data System (ADS)

Minimally/Non-invasive surgery has become increasingly widespread because of its therapeutic benefits such as less pain, less scarring, and shorter hospital stay. However, it is very difficult to eliminate the target cancer cells selectively without damaging nearby normal tissues and vessels since the tumors inside organs cannot be visually tracked in realtime with the existing imaging devices while organs are deformed by respiration and surgical instruments. Note that realtime 2D US imaging is widely used for monitoring the minimally invasive surgery such as Radiofrequency ablation; however, it is difficult to detect target tumors except high-echogenic regions because of its noisy and limited field of view. To handle these difficulties, we present a novel framework for estimating organ motion and deformed shape during respiration from the available features of 2D US images, by means of inverse kinematics utilizing 3D CT volumes at the inhale and exhale phases. First, we generate surface meshes of the target organ and tumor as well as centerlines of vessels at the two extreme phases considering surface correspondence. Then, the corresponding tetrahedron meshes are generated by coupling the internal components for volumetric modeling. Finally, a deformed organ mesh at an arbitrary phase is generated from the 2D US feature points for estimating the organ deformation and tumor position. To show effectiveness of the proposed method, the CT scans from real patient has been tested for estimating the motion and deformation of the liver. The experimental result shows that the average errors are less than 3mm in terms of tumor position as well as the whole surface shape.

Kang, Nahyup; Kim, Ji-Yeon; Kim, Kyung Hwan; Lee, Hyong-Euk; Kim, James D. K.

2013-03-01

74

Transpose jacobian based hybrid impedance control of redundant manipulators  

Microsoft Academic Search

This paper presents an efficient control scheme for compliant motion control of kinematically redundant manipulators and its evaluation using an experimental 7 degrees-of-freedom manipulator, REDIESTRO (a Redundant Dextrous Isotropically Enhanced, Seven Turning-pair RObot). A transpose Jacobian based hybrid impedance control (TJ-HIC) scheme is proposed that provides a unified approach for combining compliant motion control, redundancy resolution, and user defined secondary

M. Shah; R. V. Patel

2005-01-01

75

Jacobian Newton Polyhedra and equisingularity  

E-print Network

This is the LaTeX version of the handwritten notes of a lecture at the Kyoto Singularities Symposium held at the RIMS in April 1978. It presents the relationship of various invariants of isolated singularities of complex analytic hypersurfaces with the jacobian Newton polygon built from the polar curves. An appendix presents features of the semiring of Newton polygons, because the product of Jacobian Newton polygons corresponds to the Thom-Sebastiani sum of hypersurfaces. Analogies between mixed multiplicities and mixed volumes are noticed. They have been explained since.

Teissier, Bernard

2012-01-01

76

Extraction of human gait signatures: an inverse kinematic approach using Groebner basis theory applied to gait cycle analysis  

NASA Astrophysics Data System (ADS)

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.

Barki, Anum; Kendricks, Kimberly; Tuttle, Ronald F.; Bunker, David J.; Borel, Christoph C.

2013-05-01

77

Geometry and kinematics of Late Cretaceous inversion structures in the Jiuquan Basin, western China  

USGS Publications Warehouse

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.

Wang, B.; Chen, H.; Yang, S.; Xiao, A.; Cheng, X.; Rupp, J.A.

2005-01-01

78

Solving the Differential Biochemical Jacobian from Metabolomics Covariance Data  

PubMed Central

High-throughput molecular analysis has become an integral part in organismal systems biology. In contrast, due to a missing systematic linkage of the data with functional and predictive theoretical models of the underlying metabolic network the understanding of the resulting complex data sets is lacking far behind. Here, we present a biomathematical method addressing this problem by using metabolomics data for the inverse calculation of a biochemical Jacobian matrix, thereby linking computer-based genome-scale metabolic reconstruction and in vivo metabolic dynamics. The incongruity of metabolome coverage by typical metabolite profiling approaches and genome-scale metabolic reconstruction was solved by the design of superpathways to define a metabolic interaction matrix. A differential biochemical Jacobian was calculated using an approach which links this metabolic interaction matrix and the covariance of metabolomics data satisfying a Lyapunov equation. The predictions of the differential Jacobian from real metabolomic data were found to be correct by testing the corresponding enzymatic activities. Moreover it is demonstrated that the predictions of the biochemical Jacobian matrix allow for the design of parameter optimization strategies for ODE-based kinetic models of the system. The presented concept combines dynamic modelling strategies with large-scale steady state profiling approaches without the explicit knowledge of individual kinetic parameters. In summary, the presented strategy allows for the identification of regulatory key processes in the biochemical network directly from metabolomics data and is a fundamental achievement for the functional interpretation of metabolomics data. PMID:24695071

Nägele, Thomas; Mair, Andrea; Sun, Xiaoliang; Fragner, Lena; Teige, Markus; Weckwerth, Wolfram

2014-01-01

79

Kinematic equations for control of the redundant eight-degree-of-freedom advanced research manipulator 2  

NASA Technical Reports Server (NTRS)

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.

Williams, Robert L., II

1992-01-01

80

Kinematics of an in-parallel actuated manipulator based on the Stewart platform mechanism  

NASA Technical Reports Server (NTRS)

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.

Williams, Robert L., II

1992-01-01

81

A new approach to solve inverse kinematics of a planar flexible continuum robot  

NASA Astrophysics Data System (ADS)

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.

Amouri, Ammar; Mahfoudi, Chawki; Zaatri, Abdelouahab; Merabti, Halim

2014-10-01

82

Kinematic Point Source Moment Tensor Inversion Using a Hierarchical Bayesian Approach  

NASA Astrophysics Data System (ADS)

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.

Musta?, Marija; Tkal?i?, Hrvoje

2014-05-01

83

Exploring the alpha cluster structure of nuclei using the thick target inverse kinematics technique for multiple alpha decays  

NASA Astrophysics Data System (ADS)

We explored alpha clustering in 24Mg using the reaction 20Ne+? and the Thick Target Inverse Kinematics (TTIK) technique. 20Ne beams of energy 3.7 AMeV and 11 AMeV were delivered by the K150 cyclotron at Texas A&M University. The reaction chamber was filled with 4He gas at a pressure sufficient to stop the beam before the detectors. The energy of the light reaction products was measured by three silicon detector telescopes. The time relative to the cyclotron radiofrequency was also measured. For the first time the TTIK method was used to study both single and multiple ?-particle decays. New results were obtained on elastic resonant ? scattering, as well as on inelastic processes leading to high excitation energy systems decaying by multiple ?-particle emission. Preliminary results will be shown on events with ?-multiplicity one and two.

Barbui, M.; Hagel, K.; Goldberg, V. Z.; Natowitz, J. B.; Zheng, H.; Giuliani, G.; Rapisarda, G. G.; Wuenschel, S.; Liu, X.

2014-03-01

84

Isotopic yield distributions of transfer- and fusion-induced fission from 238U+12C reactions in inverse kinematics  

NASA Astrophysics Data System (ADS)

A 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 multinucleon 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. Complete isotopic yield distributions of fragments from well defined fissioning systems are made available. Together with the precise measurement of the fragment emission angles and velocities, this technique gives further insight into the nuclear-fission process.

Caamaño, M.; Delaune, O.; Farget, F.; Derkx, X.; Schmidt, K.-H.; Audouin, L.; Bacri, C.-O.; Barreau, G.; Benlliure, J.; Casarejos, E.; Chbihi, A.; Fernández-Domínguez, B.; Gaudefroy, L.; Golabek, C.; Jurado, B.; Lemasson, A.; Navin, A.; Rejmund, M.; Roger, T.; Shrivastava, A.; Schmitt, C.

2013-08-01

85

Isotopic Yield Distributions of Transfer- and Fusion-Induced Fission from 238U+12C Reactions in Inverse Kinematics  

E-print Network

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.

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

86

A new solution method for the inverse kinematic joint velocity calculations of redundant manipulators  

SciTech Connect

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.

Pin, F.G.; Belmans, P.F.R.; Culioli, J.C.; Carlson, D.D.; Tulloch, F.A.

1994-12-31

87

Genetic design of kinematically optimal fine tuning Stewart platform for large spherical radio telescope  

Microsoft Academic Search

This paper presents a methodology for the design of optimal kinematical characteristics of Stewart platform using genetic algorithms (GAs). The optimal kinematics index which expressed by Jacobian matrix of Stewart platform is first deduced, and then the minimum of condition numbers of Jacobian matrix in the whole trajectory tracing workspace is used as the objective function. The constrained optimal design

Y. X. Su; B. Y. Duan; C. H. Zheng

2001-01-01

88

Adjoint Inversion for Extended Earthquake Source Kinematics From Very Dense Strong Motion Data  

NASA Astrophysics Data System (ADS)

Addressing key open questions about earthquake dynamics requires a radical improvement of the robustness and resolution of seismic observations of large earthquakes. Proposals for a new generation of earthquake observation systems include the deployment of “community seismic networks” of low-cost accelerometers in urban areas and the extraction of strong ground motions from high-rate optical images of the Earth's surface recorded by a large space telescope in geostationary orbit. Both systems could deliver strong motion data with a spatial density orders of magnitude higher than current seismic networks. In particular, a “space seismometer” could sample the seismic wave field at a spatio-temporal resolution of 100 m, 1 Hz over areas several 100 km wide with an amplitude resolution of few cm/s in ground velocity. The amount of data to process would be immensely larger than what current extended source inversion algorithms can handle, which hampers the quantitative assessment of the cost-benefit trade-offs that can guide the practical design of the proposed earthquake observation systems. We report here on the development of a scalable source imaging technique based on iterative adjoint inversion and its application to the proof-of-concept of a space seismometer. We generated synthetic ground motions for M7 earthquake rupture scenarios based on dynamic rupture simulations on a vertical strike-slip fault embedded in an elastic half-space. A range of scenarios include increasing levels of complexity and interesting features such as supershear rupture speed. The resulting ground shaking is then processed accordingly to what would be captured by an optical satellite. Based on the resulting data, we perform source inversion by an adjoint/time-reversal method. The gradient of a cost function quantifying the waveform misfit between data and synthetics is efficiently obtained by applying the time-reversed ground velocity residuals as surface force sources, back-propagating onto the locked fault plane through a seismic wave simulation and recording the fault shear stress, which is the adjoint field of the fault slip-rate. Restricting the procedure to a single iteration is known as imaging. The source reconstructed by imaging reproduces the original forward model quite well in the shallow part of the fault. However, the deeper part of the earthquake source is not well reproduced, due to the lack of data on the side and bottom boundaries of our computational domain. To resolve this issue, we are implementing the complete iterative procedure and we will report on the convergence aspects of the adjoint iterations. Our current work is also directed towards addressing the lack of data on other boundaries of our domain and improving the source reconstruction by including teleseismic data for those boundaries and non-negativity constraints on the dominant slip-rate component.

Ampuero, J. P.; Somala, S.; Lapusta, N.

2010-12-01

89

Postseismic Deformation Following the 2010 M = 7.2 El Mayor-Cucapah Earthquake: Observations, Kinematic Inversions, and Dynamic Models  

NASA Astrophysics Data System (ADS)

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 M = 7.2 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 M = 7.2 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.

Rollins, Christopher; Barbot, Sylvain; Avouac, Jean-Philippe

2015-01-01

90

Multi-GPU Jacobian Accelerated Computing for Soft Field Tomography  

PubMed Central

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

Borsic, A.; Attardo, E. A.; Halter, R. J.

2012-01-01

91

Closed-form inverse kinematics for interventional C-arm X-ray imaging with six degrees of freedom: modeling and application.  

PubMed

For trauma and orthopedic surgery, maneuvering a mobile C-arm fluoroscope into a desired position to acquire an X-ray is a routine surgical task. The precision and ease of use of the C-arm becomes even more important for advanced interventional imaging techniques such as parallax-free X-ray image stitching. Today's standard mobile C-arms have been modeled with only five degrees of freedom (DOF), which definitely restricts their motions in 3-D Cartesian space. In this paper, we present a method to model both the mobile C-arm and patient's table as an integrated kinematic chain having six DOF without constraining table position. The closed-form solutions for the inverse kinematics problem are derived in order to obtain the required values for all C-arm joint and table movements to position the fluoroscope at a desired pose. The modeling method and the closed-form solutions can be applied to general isocentric or nonisocentric mobile C-arms. By achieving this we develop an efficient and intuitive inverse kinematics-based method for parallax-free panoramic X-ray imaging. In addition, we implement a 6-DOF C-arm system from a low-cost mobile fluoroscope to optimally acquire X-ray images based solely on the computation of the required movement for each joint by solving the inverse kinematics on a continuous basis. Through simulation experimentation, we demonstrate that the 6-DOF C-arm model has a larger working space than the 5-DOF model. C-arm repositioning experiments show the practicality and accuracy of our 6-DOF C-arm system. We also evaluate the novel parallax-free X-ray stitching method on phantom and dry bones. Using five trials, results show that parallax-free panoramas generated by our method are of high visual quality and within clinical tolerances for accurate evaluation of long bone geometry (i.e., image and metric measurement errors are less than 1% compared to ground-truth). PMID:22293978

Wang, Lejing; Fallavollita, Pascal; Zou, Rui; Chen, Xin; Weidert, Simon; Navab, Nassir

2012-05-01

92

Insights into the kinematics of a volcanic caldera drop: Probabilistic finite-source inversion of the 1996 Brdarbunga, Iceland, earthquake  

E-print Network

by hypocentre distributions in several volcanic areas. These include Mt. St. Helens, USA (Scandone and Malone spectral-element method seismology The accurate modelling and prediction of volcanic eruptions depends. Knowledge concerning the kinematics of a caldera in the course of an eruption is therefore essential. Here

Utrecht, Universiteit

93

A Dexterity Measure for the Kinematic Control of Robot Manipulator with Redundany  

E-print Network

We have derived a new performance measure, product of minors of the Jacobian matrix, that tells how far kinematically redundant manipulators are from singularity. It was demonstrated that previously used performance ...

Chang, Pyung H.

1988-02-01

94

Inverse kinematics of redundant systems driver IKORv1.0-2.0 (full space parameterization with orientation control, platform mobility, and portability)  

SciTech Connect

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.

Hacker, C.J.; Fries, G.A.; Pin, F.G.

1997-01-01

95

Kinematics of the Local Universe. X. H_0 from the inverse B-band Tully-Fisher relation using diameter and magnitude limited samples  

E-print Network

We derive the value of H_0 using the inverse diameter and magnitude B-band Tully-Fisher relations and the large all-sky sample KLUN (5171 spiral galaxies). Our kinematical model was that of Peebles centered at Virgo. Our calibrator sample consisted of 15 field galaxies with cepheid distance moduli measured mostly with HST. A straightforward application of the inverse relation yielded H_0\\approx 80 km/sec/Mpc for the diameter relation and H_0\\approx 70 km/sec/Mpc for the magnitude relation. H_0 from diameters is about 50 percent and from magnitudes about 30 percent larger than the corresponding direct estimates (cf. Theureau et al. 1997b). This discrepancy could not be resolved in terms of a selection effect in log V_max nor by the dependence of the zero-point on the Hubble type. We showed that a new, calibrator selection bias (Teerikorpi et al. 1999), is present. By using samples of signicificant size (N=2142 for diameters and N=1713 for magnitudes) we found for a homogeneous distribution of galaxies (alpha=0) H_0\\approx 50 km/sec/Mpc for both the diameters and magnitudes. Also H_0's from a fractal distribution of galaxies (decreasing radial number density gradient alpha=0.8) agree with the direct predictions. This is the first time when the inverse Tully-Fisher relation clearly lends credence to small values of the Hubble constant H_0 and to long cosmological distance scale consistently supported by Sandage and his collaborators.

T. Ekholm; P. Teerikorpi; G. Theureau; M. Hanski; G. Paturel; L. Bottinelli; L. Gouguenheim

1999-04-27

96

Toward resolving stable high-resolution kinematic rupture models of large earthquakes by joint inversion of seismic, geodetic and tsunami observations  

NASA Astrophysics Data System (ADS)

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.

Yue, Han

97

Differential Kinematics Of Contemporary Industrial Robots  

NASA Astrophysics Data System (ADS)

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

Szkodny, T.

2014-08-01

98

Topology of the compactified Jacobians of singular curves  

Microsoft Academic Search

We compute the Euler number of the compactified Jacobian of a curve whose minimal unibranched normalization has only plane irreducible singularities with characteristic Puiseux exponents (p, q), (4, 2q, s), (6, 8, s), or (6, 10, s). Further, we derive a combinatorial method to compute the Betti numbers of the compactified Jacobian of an unibranched rational curve with singularities like

Jens Piontkowski

2007-01-01

99

SIMPSON JACOBIANS OF REDUCIBLE CURVES ANA CRISTINA LOPEZ MARTIN  

E-print Network

SIMPSON JACOBIANS OF REDUCIBLE CURVES ANA CRISTINA L´OPEZ MART´IN Abstract. For any projective curve X let M d (X) be the Simpson moduli space of pure dimension one rank 1 degree d sheaves. In this paper we give explicitly the structure of this compactified Simpson Jacobian for the following

Martín, Ana Cristina López

100

Extraction of Gamow-Teller strength distributions from 56Ni and 55Co via the (p,n) reaction in inverse kinematics  

NASA Astrophysics Data System (ADS)

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.

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

101

Kinematic programming alternatives for redundant manipulators  

Microsoft Academic Search

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

John Baillieul

1985-01-01

102

The mechanical design and kinematics accuracy analysis of a fine tuning stable platform for the large spherical radio telescope  

Microsoft Academic Search

A large Stewart platform for fine tuning of the feed source tracing is presented in this paper. The model of kinematics control is developed with coordinate transformation, and a quasi-static load analysis is made by virtual work principle with Jacobian matrix because the tracing speed is slow. The kinematics accuracy model is derived by position vector analysis, and the kinematics

Y. X. Su; B. Y. Duan

2000-01-01

103

Structural and geochronological constraints on the kinematics and timing of Cenozoic inversion of the Salta rift in NW Argentina  

NASA Astrophysics Data System (ADS)

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.

Kortyna, C. D.; DeCelles, P. G.; Carrapa, B.

2012-12-01

104

A global search inversion for earthquake kinematic rupture history: Application to the 2000 western Tottori, Japan earthquake  

USGS Publications Warehouse

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.

Piatanesi, A.; Cirella, A.; Spudich, P.; Cocco, M.

2007-01-01

105

Designing Equally Fault-Tolerant Configurations for Kinematically Redundant Manipulators  

E-print Network

. Building on previous work, it is shown that for a robot manipulator working in three-dimensional workspace degrees of freedom. A corresponding family of Jacobians with this property is identified. It is also shownDesigning Equally Fault-Tolerant Configurations for Kinematically Redundant Manipulators Rodney G

Maciejewski, Anthony A.

106

Kinematic control of redundant robot manipulators: A tutorial  

Microsoft Academic Search

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

Bruno Siciliano

1990-01-01

107

Jacobian Joint Adaptation to Noise, Channel and Vocal Tract Length   

E-print Network

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 to these factors is proposed...

Shimodaira, Hiroshi; Sakai, Nobuyoshi; Nakai, Mitsuru; Sagayama, Shigeki

108

Generic robotic kinematic generator for virtual environment interfaces  

NASA Astrophysics Data System (ADS)

The expansion of robotic systems' performance, as well as the need for such machines to work in complex environments (hazardous, small, distant, etc.), involves the need for user interfaces which permit efficient teleoperation. Virtual Reality based interfaces provide the user with a new method for robot task planning and control: he or she can define tasks in a very intuitive way by interacting with a 3D computer generated representation of the world, which is continuously updated thanks to multiple sensors fusion and analysis. The Swiss Federal Institute of Technology has successfully tested different kinds of teleoperations. In the early 90s, a transatlantic teleoperation of a conventional robot manipulator with a vision feedback system to update the virtual world was achieved. This approach was then extended to perform teleoperation of several mobile robots (Khepera, Koala) as well as to control microrobots used for microsystems' assembly in the micrometer range. One of the problems encountered with such an approach is the necessity to program a specific kinematic algorithm for each kind of manipulator. To provide a more general solution, we started a project aiming at the design of a 'kinematic generator' (CINEGEN) for the simulation of generic serial and parallel mechanical chains. With CINEGEN, each manipulator is defined with an ascii file description and its attached graphics files; inserting a new manipulator simply requires a new description file, and none of the existing tools require modification. To have a real time behavior, we have chosen a numerical method based on the pseudo-Jacobian method to generate the inverse kinematics of the robot. The results obtained with an object-oriented implementation on a graphic workstation are presented in this paper.

Flueckiger, Lorenzo; Piguet, Laurent; Baur, Charles

1996-12-01

109

On closed form expressions for the singular-value decomposition of an orientational Jacobian and its application to a motion simulator  

SciTech Connect

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.

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

110

Inversion strategies for visco-acoustic waveform inversion  

NASA Astrophysics Data System (ADS)

Visco-acoustic waveform inversion can potentially yield quantitative images of the distribution of both velocity and the attenuation parameters from seismic data. Intrinsic P-wave attenuation has been of particular interest, but has also proven challenging. Frequency-domain inversion allows attenuation and velocity relations to be easily incorporated, and allows a natural multiscale approach. The Laplace-Fourier approach extends this to allow the natural damping of waveforms to enhance early arrivals. Nevertheless, simultaneous inversion of velocity and attenuation leads to 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 gradients 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. We show that at a given modelling frequency, the Fréchet derivatives corresponding to these two parameter classes differ only by a 90° phase shift, meaning that the magnitudes of resulting model updates will be unscaled, and will not reflect the expected magnitudes in realistic (Q-1 ? 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. To solve these issues, we introduce an attenuation scaling term (the inverse of a penalty term) that is used to pre-condition the gradient by controlling the magnitudes of the updates to the attenuation parameters. 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 important in retrieving a reliable attenuation model when strong time-damping is applied. In a final test with our synthetic model, we successfully carry out visco-acoustic inversions of noise-contaminated data.

Kamei, R.; Pratt, R. G.

2013-08-01

111

Efficient 2D inversion of long ERT sections  

NASA Astrophysics Data System (ADS)

In this work a new algorithm for the efficient and fast two dimensional (2D) inversion of long electrical resistivity tomography (ERT) sections is introduced. The algorithm is based on 2.5D finite element method (FEM) scheme to solve Poisson's equation that describes the current flow into the earth's subsurface. The adjoint equation technique was incorporated into the FEM framework to estimate the sensitivity values. The reconstructed 2D resistivity models are recovered through an iterative, non-linear smoothness constrained least-squares approach. The algorithm further incorporates an experimental procedure to avoid the calculation and storage of the entire Jacobian matrix. The basic concept of this new algorithm relies on the fact that for every measurement there is a number of model parameters which are located in parts of the 2-D model at distant locations from potential and current electrodes. The corresponding absolute Jacobian matrix values in such cases are very small (almost zero) and can be omitted by the Jacobian calculation. Around every measurement a fixed rectangular threshold region is defined a-priori based on geometrical criteria. The algorithm calculates only Jacobian matrix values for the model parameters that are included in this threshold area omitting the calculation of the Jacobian entries related to model parameters outside this region. This approach speeds up the Jacobian matrix calculations while the efficient storage of the sparse Jacobian and Smoothness matrices and the inversion using an iterative routine like LSQR method increase significantly the inversion speed and reduce the memory requirements. The new algorithm is almost more than one order of magnitude (~ 30 times) faster and consumes one order of magnitude (~ 90%) less storage memory than the original one based on full Jacobian calculations for typical applications. The application of the new algorithm to synthetic and real data sets shows that the reconstructed models exhibit comparable accuracy to the standard inversion approach.

Tsourlos, Panagiotis; Papadopoulos, Nikos; Papazachos, Costas; Yi, Myeong-Jong; Kim, Jung-Ho

2014-06-01

112

Power system steady-state stability and the load-flow Jacobian  

Microsoft Academic Search

The relationship is presented 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. The

P. W. Sauer; M. A. Pai

1990-01-01

113

Optimum Kinematic Design for a Seven Degree of Freedom Manipulator  

Microsoft Academic Search

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

John M. Hollerbach

1985-01-01

114

Arithmetic of Generalized Jacobians Isabelle Dech`ene  

E-print Network

of Koblitz [Kob87] and Miller [Mil86] of using elliptic curves in public-key cryptography would, to sayGamal, the Elliptic and Hyperelliptic Curve Cryptosystems, XTR, LUC as well as CEILIDH can all naturally here study the simplest nontrivial generalized Jacobians of an elliptic curve. In this first

115

Jacobians with a vanishing theta-null in genus 4  

E-print Network

In this paper we prove a conjecture of Hershel Farkas [8] that if a 4-dimensional principally polarized abelian variety has a vanishing theta-null, and the hessian of the theta function at the corresponding point of order two is degenerate, the abelian variety is a Jacobian. We also discuss

Samuel Grushevsky; Riccardo Salvati Manni

2006-01-01

116

Classical Integrable Systems and Billiards Related to Generalized Jacobians  

Microsoft Academic Search

We study some classical integrable systems of dynamics (the Euler top in space, the asymptotic geodesic motion on an ellipsoid) which are linearized on unramified coverings of generalized Jacobian varieties. We find explicit expressions for so called root functions living on such coverings which enable us to solve the problems in terms of generalized theta-functions. In addition, general and asymptotic

Yu. Fedorov

1999-01-01

117

Exploring Strange Nonchaotic Attractors through Jacobian Elliptic Functions  

ERIC Educational Resources Information Center

We demonstrate the effectiveness of Jacobian elliptic functions (JEFs) for inquiring into the reshaping effect of quasiperiodic forces in nonlinear nonautonomous systems exhibiting strange nonchaotic attractors (SNAs). Specifically, we characterize analytically and numerically some reshaping-induced transitions starting from SNAs in the context of…

Garcia-Hoz, A. Martinez; Chacon, R.

2011-01-01

118

On the kinematic design of spherical three-degree-of-freedom parallel manipulators  

Microsoft Academic Search

This article studies the kinematic design of different types of spherical three-degree-of-freedom parallel manipulators. The mechanical architectures presented have been introduced elsewhere. However, designs having at least one isotropic configuration are suggested here for the first time. Isotropic configurations are defined, in turn, as those configurations in which the Jacobian matrix, mapping the angular velocity vector of the effector into

Clement M. Gosselin; Eric Lavoie

1993-01-01

119

The Jacobian and the Ginzburg-Landau energy  

Microsoft Academic Search

.   We study the Ginzburg-Landau functional\\u000a \\u000a \\u000a \\u000a \\u000a \\u000a \\u000a \\u000a for , where U is a bounded, open subset of . We show that if a sequence of functions satisfies , then their Jacobians are precompact in the dual of for every . Moreover, any limiting measure is a sum of point masses. We also characterize the -limit of the functionals , in terms

Robert L. Jerrard; Halil Mete Soner

2002-01-01

120

Kinematics of a three-degree-of-freedom in-parallel actuated manipulator mechanism  

Microsoft Academic Search

This paper presents the first and second order kinematic analysis of a three-degrees-of-freedom 3-RPS parallel robot mechanism. The position and orientation parameters of the moving platform of this mechanism are six, however only three of them are independent. The Jacobian of the mechanism is a 3 by 6 rectangular matrix. This imposes difficulties on the kinematic analysis of this mechanism.

Zhen Huang

1997-01-01

121

The Jacobian and the Ginzburg-Landau Energy  

Microsoft Academic Search

We study the Ginzburg-Landau functionalI ffl (u):=1ln(1=ffl) Z U12 jruj2+14ffl2(1;juj2)2dx #for u2H1(U # IR2), where U is a bounded, open subset of IR2. We show that if a sequence offunctions ufflsatisfies sup I ffl (uffl) !1,then their Jacobians Jufflare precompact in the dual ofC0#ffc for every ff2(0# 1]. Moreover, any limiting measure is a sum of point masses. We alsocharacterize

Robert L. Jerrard; Halil Mete Soner

1999-01-01

122

REACTIVE TRANSPORT MODELING USING A PARALLEL FULLY-COUPLED SIMULATOR BASED ON PRECONDITIONED JACOBIAN-FREE NEWTON-KRYLOV  

SciTech Connect

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.

Luanjing Guo; Chuan Lu; Hai Huang; Derek R. Gaston

2012-06-01

123

ATLAS MOTION PLATFORM MECANUM WHEEL JACOBIAN IN THE VELOCITY AND STATIC FORCE DOMAINS  

E-print Network

ATLAS MOTION PLATFORM MECANUM WHEEL JACOBIAN IN THE VELOCITY AND STATIC FORCE DOMAINS Jonathan J. Atlas is a six degree of freedom vehicle op- erating training simulator motion platform where orienting force Jacobians; normal forces. MATRICE JACOBIENNE DES ROUES MECANUM SIMULATOUR DE MOUVEMENT ATLAS DANS

Hayes, John

124

Timing and Kinematics of Cretaceous to Paleogene inversion at the SE margin of the Central European Basin System: Part 2, Thermochronology  

NASA Astrophysics Data System (ADS)

During the Late Cretaceous to Early Tertiary some parts of the Central European Basin System (CEBS) were uplifted along NW-SE to WNW-ESE striking compressive fault systems. As a result Pre-Zechstein (Permian) basement is exposed at the southern border of the CEBS from Central Germany to the sudetes still further east (e.g. Harz Mountains, Thuringian Forest). Thrust-related basins like the Subhercynian Cretaceous Basin (SCB) in the foreland of the Harz Mountains accumulated up to 2500m of siliciclastic and chemical sediments in only 10 million years (Late Turonian to Lower Campanian, Voigt et al., 2006). By means of low-temperature thermochronology it is possible to characterise these basin inversion processes with respect to timing, pattern and rates of cooling and exhumation. Differed authors have already applied Apatite Fission Track analysis (AFT) in certain areas of the southern margin of CEBS. Thomson and Zeh (2000) published AFT apparent ages of 69 to 81 Ma for the Ruhla Crystalline Complex in the Thuringian Forest. Similar AFT-ages (73-84 Ma) of granitoids from the Harz Mountains were reported by Thomson et al. (1997). The late Carboniferous felsic volcanic rocks near Halle yield a much broader range of AFT apparent ages (75-108 Ma; Jacobs and Breitkreuz, 2003). Comparable AFT-ages (84-90 Ma) had been also observed for gabbros from the north-eastern part of the Mid German Crystalline High (Ventura et al. 2003). The present study tries to bridge some of the major gaps in the regional distribution of thermochronological data by analysing samples from central and southern parts of the CEBS. Overall almost 50 AFT-ages from Saxony-Anhalt, Lower Saxony, Thuringia, Hesse and North Rhine-Westphalia were measured. Emphasis is placed on the regions from the Harz Mountains to the Rhenish Uplands and the Thuringian Forest and its foreland. Furthermore, apatite (U-Th)/He thermochronology is used to better constrain the time-temperature history models. Apart from some mixed age information two different age groups can be recognized. A major group that is similar to the one reported above points to a short but intense pulse of exhumation and inversion in Coniacian to Campanian time. A younger, less significant age cluster yields information on a second phase of cooling and exhumation in the Paleocene-Eocene. The length distribution of AFT data leads to the assumption of rapid, partially multi-phase, exhumation events. In addition, the data of this study provides indications for thick Jurassic burial that likely reflect phases of Mesozoic extensional tectonics in at least parts of the CEBS. Jacobs, J., Breitkreuz, C. (2003): Zircon and apatite fission-track thermochronology of Late Carboniferous volcanic rocks of the NE German Basin. International Journal of Earth Sciences (Geologische Rundschau), 92, 165-172. Thomson, S., Brix, M., Carter, A. (1997): Late Cretaceous denudation of the Harz Massif assessed by apatite fission track analysis. In: G. Büchel and H. Lützner (Editors), Regionale Geologie von Mitteleuropa, 149. Hauptversammlung Deutsche Geologische Gesellschaft, Jena. Schriftenreihe der Deutschen Geologischen Gesellschaft, 3, 115. Thomson, S.N., Zeh, A. (2000): Fission-track thermochronology of the Ruhla Crystalline Complex:. New constraints on the post-Variscan thermal evolution of the NW Saxo-Bohemian Massif. Tectonophysics, 324, 17-35. Ventura, B., Lisker, F., Kopp, J. (2003): Apatite fission track data from the dill-core Züllsdorf 1/63: implications for the reconstruction of the post Variscan exhumation of the Mid German Crystalline High. Zeitschrift für Geologische Wissenschaften, 31, 251-261. Voigt, T., Wiese, F., von Eynatten, H., Franzke, H.-J. & Gaupp, R. (2006): Facies evolution of syntectonic Upper Cretaceous deposits in the Subhercynian Cretaceous Basin and adjoining areas (Germany). Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 157/2, 203-244.

Hoffmann, V.-E.; Dunkl, I.; von Eynatten, H.; Jähne, F.; Voigt, T.; Kley, J.

2009-04-01

125

Kinematics of the six-degree-of-freedom force-reflecting Kraft Master  

NASA Technical Reports Server (NTRS)

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.

Williams, Robert L., II

1991-01-01

126

The Kinematic Analysis of a Symmetrical Three-Degree-of-Freedom Planar Parallel Manipulator  

Microsoft Academic Search

Presented in this paper is the kinematic analysis of a symmetrical three-degree-of-freedom planar parallel manipulator. In opposite to serial manipulators, parallel manipulators can admit not only multiple inverse kinematic solutions, but also multiple direct kinematic solutions. This property produces more complicated kinematic models but allows more flexibility in trajectory planning. To take into account this property, the notion of aspects,

Damien Chablat; Philippe Wenger

2007-01-01

127

Kinematic Fanatic  

NSDL National Science Digital Library

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.

Museum of Science, Boston

2005-01-01

128

Halo Kinematics  

E-print Network

I summarize recent observations of the kinematics of hot tracers in elliptical galaxy halos (globular clusters, planetary nebulae, and integrated stellar light), and what these tell us about the dynamics, dark matter content, and formation of ellipticals. A generic result is the ubiquity of dark matter halos in ellipticals. Studies of globular clusters and planetary nebulae are now finding outer-halo rotation in many ellipticals, with V/sigma ~ 1 beyond a few R_e. In some giant ellipticals (M49, M87), there are possible kinematic differences between metal-poor and metal-rich globular clusters. These results are consistent with a merger origin for ellipticals. High-quality data and new modelling techniques now make it possible to determine simultaneously the orbital anisotropy and gravitational potential in ellipticals from integrated-light measurements; such studies now provide the best evidence for dark matter halos in ellipticals.The new generation of 8-10m telescopes, with multi-object and integral-field spectrographs, will dramatically increase sample sizes of discrete tracers and provide two-dimensional spectroscopy of elliptical halos. New methods of analysis will allow robust determinations of stellar kinematics and dark matter distributions in a much larger number of ellipticals. Comparison with numerical simulations, which are becoming ever more detailed and physically realistic, will become increasingly important.

Terry Bridges

1998-11-09

129

Jacobian Adaptation of HMM with Initial Model Selection for Noisy Speech Recognition   

E-print Network

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...

Shimodaira, Hiroshi; Kato, Yukata; Akae, Toshihiko; Nakai, Mitsuru; Sagayama, Shigeki

130

Kinematic functions for the 7 DOF robotics research arm  

NASA Technical Reports Server (NTRS)

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.

Kreutz, K.; Long, M.; Seraji, Homayoun

1989-01-01

131

Approximating Human Reaching Volumes Using Inverse Kinematics  

E-print Network

, Switzerland Abstract This paper presents a system to analyse the reaching capabilities of the human body. Our system for the human body. Our research is motivated due to the necessity of systems which help to manage. Introduction Virtual Humans are a valuable medium for gaining knowledge and understanding about the human body

Rodríguez, Inmaculada

132

Fault tolerant kinematic control of hyper-redundant manipulators  

NASA Technical Reports Server (NTRS)

Hyper-redundant spatial manipulators possess fault-tolerant features because of their redundant structure. The kinematic control of these manipulators is investigated with special emphasis on fault-tolerant control. The manipulator tasks are viewed in the end-effector space while actuator commands are in joint-space, requiring an inverse kinematic algorithm to generate joint-angle commands from the end-effector ones. The rate-inverse kinematic control algorithm presented in this paper utilizes the pseudoinverse to accommodate for joint motor failures. An optimal scale factor for the robust inverse is derived.

Bedrossian, Nazareth S.

1994-01-01

133

MORAL KINEMATICS 1 Running head: MORAL KINEMATICS  

E-print Network

KINEMATICS 2 #12;MORAL KINEMATICS 3 Abstract Harmful events often have a strong physical component, e.g. car accidents, plane crashes, fist fights, and military interventions. Yet there is very little systematic work

Reber, Paul J.

134

Inverse Consistent Mapping in 3D Deformable Image Registration: Its Construction and Statistical Properties  

E-print Network

the algorithm by applying it to the serial MRI scans of a clinical case of semantic dementia. The statistical-trivial Jacobian map do not follow a log-normal distribution with zero mean. Statistically significant differencesInverse Consistent Mapping in 3D Deformable Image Registration: Its Construction and Statistical

Thompson, Paul

135

The Kinematic Analysis of a Symmetrical Three-Degree-of-Freedom  

E-print Network

1 The Kinematic Analysis of a Symmetrical Three-Degree-of-Freedom Planar Parallel Manipulator is the kinematic analysis of a symmetrical three-degree-of-freedom planar parallel manipulator. In opposite to serial manipulators, parallel manipulators can admit not only multiple inverse kinematic solutions

Paris-Sud XI, Université de

136

Kinematic analysis of a Novel 3DOF hybrid mechanical arm  

Microsoft Academic Search

The kinematic analysis of the mechanical arm plays an important role on the applications of the mechanical arms. In this paper, a novel 3-DOF hybrid mechanical arm is proposed at first. Then the direct and inverse displacement equations of the mechanical arm, the direct solutions or inverse solutions are unique, are developed based on its architecture feature. At last, the

Y. B. Li; Z. L. Jin

2008-01-01

137

Integer solutions of integral inequalities and H-invariant Jacobian Poisson structures  

E-print Network

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.

Giovanni Ortenzi; Vladimir Rubtsov; Serge Roméo Tagne Pelap

2011-03-22

138

NON-CYCLIC SUBGROUPS OF JACOBIANS OF GENUS TWO CURVES WITH COMPLEX MULTIPLICATION  

E-print Network

, Koblitz [12] then proposed using Jacobians of hyperelliptic curves. In elliptic curve cryptography ROBENHAGEN RAVNSHØJ Abstract. Let E be an elliptic curve dened over a nite eld. Balasubrama- nian and Koblitz eld extension of the ground eld. 1. Introduction In [11], Koblitz described how to use elliptic curves

139

Construction of the Jacobian matrix for fluorescence diffuse optical tomography using a perturbation Monte Carlo method  

NASA Astrophysics Data System (ADS)

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.

Zhang, Xiaofeng

2012-03-01

140

Lefschetz classes of simple factors of Fermat Jacobian of prime degree over finite fields  

E-print Network

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.

Sugiyama, Rin

2012-01-01

141

Jacobian matrix algorithm for Lyapunov exponents of the discrete fractional maps  

NASA Astrophysics Data System (ADS)

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.

Wu, Guo-Cheng; Baleanu, Dumitru

2015-05-01

142

Approximate Jacobian elliptic function solution of the modified KdV equation by homotopy perturbation method  

Microsoft Academic Search

Using He's homotopy perturbation method (HPM), the modified KdV equation which has not a small parameter is solved. The approximate Jacobi elliptic function solution is obtained. When the modulus of the Jacobian function tends to unit or zero, the corresponding solitary wave solution and trigonometric function solution are obtained. The results reveal that the HPM is very effective, convenient and

T-L Lou; J-M Zhu

2008-01-01

143

Derivation of the regularized chiral Jacobian using the zeta function method  

SciTech Connect

Using the zeta function method, a general formula for the regularized chiral Jacobian to theories including non-Hermitian Dirac operators D-script defined in arbitrary even-dimensional Euclidean space is derived. The agreement of this formula with the results obtained in the differential geometric approach is also clarified.

Wang, R.

1988-10-01

144

The role of the Jacobian in the adaptive discontinuous Galerkin method for the  

E-print Network

The role of the Jacobian in the adaptive discontinuous Galerkin method for the compressible Euler ingredients of the adaptive discontinuous Galerkin methods recently devel- oped in [7, 8]. We demonstrate the adaptive discontinuous Galerkin method for the numerical approximation of the compressible Euler equations

Hartmann, Ralf

145

Principal Component Geostatistical Approach for large-dimensional inverse problems  

NASA Astrophysics Data System (ADS)

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.

Kitanidis, P. K.; Lee, J.

2014-07-01

146

Principal Component Geostatistical Approach for large-dimensional inverse problems  

PubMed Central

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

Kitanidis, P K; Lee, J

2014-01-01

147

Inverse robot calibration using artificial neural networks  

Microsoft Academic Search

Robot end-effector locations (position and orientation) achieved by controlling joint values obtained from a robot controller will, in general, deviate from the desired location due to inaccuracies in the internal kinematic model. Inverse calibration is defined as finding the corrected joint values to drive a robot so that deviations of the end-effector are minimised. Conventional numerical approaches to the inverse

Francis L. N-Nagy

1996-01-01

148

Three-dimensional parallel distributed inversion of CSEM data using a direct forward solver  

NASA Astrophysics Data System (ADS)

For 3-D inversion of controlled-source electromagnetic (CSEM) data, increasing availability of high-performance computers enables us to apply inversion techniques that are theoretically favourable, yet have previously been considered to be computationally too demanding. We present a newly developed parallel distributed 3-D inversion algorithm for interpreting CSEM data in the frequency domain. Our scheme is based on a direct forward solver and uses Gauss-Newton minimization with explicit formation of the Jacobian. This combination is advantageous, because Gauss-Newton minimization converges rapidly, limiting the number of expensive forward modelling cycles. Explicit calculation of the Jacobian allows us to (i) precondition the Gauss-Newton system, which further accelerates convergence, (ii) determine suitable regularization parameters by comparing matrix norms of data- and model-dependent terms in the objective function and (iii) thoroughly analyse data sensitivities and interdependencies. We show that explicit Jacobian formation in combination with direct solvers is likely to require less memory than combinations of direct solvers and implicit Jacobian usage for many moderate-scale CSEM surveys. We demonstrate the excellent convergence properties of the new inversion scheme for several synthetic models. We compare model updates determined by solving either a system of normal equations or, alternatively, a linear least-squares system. We assess the behaviour of three different stabilizing functionals in the framework of our inversion scheme, and demonstrate that implicit regularization resulting from incomplete iterative solution of the model update equations helps stabilize the inversion. We show inversions of models with up to two million unknowns in the forward solution, which clearly demonstrates applicability of our approach to real-world problems.

Grayver, A. V.; Streich, R.; Ritter, O.

2013-06-01

149

A Theory of Generalized Inverses Applied to Robotics  

Microsoft Academic Search

Robokcs research has made extensive use of techniques based on me Moore-Penrose inverse, or generalized inverse, of matri als. Recently it has been pointed out how noninvariant results may, in general, be obtained by applying these techniques to other areas of robotics, namely hybrid control and inverse ve locity kinematics. Unfortunately, the problems are not restricted to just these particular

Keith L. Doty; Claudio Melchiorri; Claudio Bonivento

1993-01-01

150

Regularity of mappings inverse to Sobolev mappings  

SciTech Connect

For homeomorphisms {phi}:{Omega}{yields}{Omega}' on Euclidean domains in R{sup n}, n{>=}2, necessary and sufficient conditions ensuring that the inverse mapping belongs to a Sobolev class are investigated. The result obtained is used to describe a new two-index scale of homeomorphisms in some Sobolev class such that their inverses also form a two-index scale of mappings, in another Sobolev class. This scale involves quasiconformal mappings and also homeomorphisms in the Sobolev class W{sup 1}{sub n-1} such that rankD{phi}(x){<=}n-2 almost everywhere on the zero set of the Jacobian det D{phi}(x). Bibliography: 65 titles.

Vodop'yanov, Sergei K [S.L. Sobolev Institute for Mathematics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)

2012-10-31

151

Construction of Pairing-Friendly Hyperelliptic Curves Based on the Closed Formulae of the Order of the Jacobian Group  

NASA Astrophysics Data System (ADS)

An explicit construction of pairing-friendly hyperelliptic curves with ordinary Jacobians was firstly given by D. Freeman for the genus two case. In this paper, we give an explicit construction of pairing-friendly hyperelliptic curves of genus two and four with ordinary Jacobians based on the closed formulae for the order of the Jacobian of special hyperelliptic curves. For the case of genus two, we prove the closed formula for curves of type y2 = x5 + c. By using the formula, we develop an analogue of the Cocks-Pinch method for curves of type y2 = x5 + c. For the case of genus four, we also develop an analogue of the Cocks-Pinch method for curves of type y2 = x9 + cx. In particular, we construct the first examples of pairing-friendly hyperelliptic curves of genus four with ordinary Jacobians.

Comuta, Aya; Kawazoe, Mitsuru; Takahashi, Tetsuya; Yoshizawa, Isamu

152

Determination of caustic surfaces using point spread function and ray Jacobian and Hessian matrices.  

PubMed

Existing methods for determining caustic surfaces involve computing either the flux density singularity or the center of curvature of the wavefront. However, such methods rely rather heavily on ray tracing and finite difference methods for estimating the first- and second-order derivative matrices (i.e., Jacobian and Hessian matrices) of a ray. The main reason is that previously the analytical expressions of these two matrices have been tedious or even impossible. Accordingly, the present study proposes a robust numerical method for determining caustic surfaces based on a point spread function and the established analytical Jacobian and Hessian matrices of a ray by our group. It is shown that the proposed method provides a convenient and computationally straightforward means of determining the caustic surfaces of both simple and complex optical systems without the need for analytical equations, and is substantially different from the two existing methods. PMID:25321667

Lin, Psang Dain

2014-09-10

153

Inverse Psoriasis  

MedlinePLUS

... With Health Plans For Your Patients Donate Inverse Psoriasis Inverse psoriasis (also known as intertriginous psoriasis) shows ... therapy or biologic medications to control the condition. Psoriasis About Psoriasis Symptoms and Diagnosis Types of Psoriasis ...

154

Multiscale modeling of polycrystalline materials with Jacobian-free multiscale method (JFMM)  

NASA Astrophysics Data System (ADS)

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 \\upalpha -RDX (cyclotrimethylene trinitramine) polycrystal is verified against the computational homogenization based two-level finite element (FE2) multiscale method. Numerical examples demonstrate that while the rate of convergence of Newton iterations for the JFMM and FE2 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 (n) at the macroscale. The storage requirement for the JFMM increases linearly with increasing n , whereas, it increases as approximately O(n^{7/4}) for the FE2 method.

Rahul; De, Suvranu

2015-02-01

155

The Photometric and Kinematic Structure of Face-on Disk Galaxies. III. Kinematic Inclinations from H? Velocity Fields  

NASA Astrophysics Data System (ADS)

Using the integral field unit DensePak on the WIYN 3.5 m telescope we have obtained H? 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 kin = 23° 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° and 6% at 30°. 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° and 5% at 30°. 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.

Andersen, David R.; Bershady, Matthew A.

2013-05-01

156

Magnetotelluric Inversion in a 2D Anisotropic Environment  

NASA Astrophysics Data System (ADS)

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.

Mandolesi, E.; Jones, A. G.

2012-04-01

157

Real time markerless motion tracking using linked kinematic chains  

DOEpatents

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.

Luck, Jason P. (Arvada, CO); Small, Daniel E. (Albuquerque, NM)

2007-08-14

158

Kinematics of A 3-PRP planar parallel robot  

E-print Network

Recursive modelling for the kinematics of a 3-PRP planar parallel robot is presented in this paper. Three planar chains connecting to the moving platform of the manipulator are located in a vertical plane. Knowing the motion of the platform, we develop the inverse kinematics and determine the positions, velocities and accelerations of the robot. Several matrix equations offer iterative expressions and graphs for the displacements, velocities and accelerations of three prismatic actuators.

Chablat, Damien

2009-01-01

159

Geologic constraints on seismic inversion  

SciTech Connect

Velocity model estimation from seismic data using prestack depth migration is an underdetermined problem: there are many subtly different models which are not kinematically equivalent. As these models can give rise to dramatically different interpretations and decisions there is a clear need for a selection criterion in order to choose the best (i.e. geologically most plausible) one. Interpreter guided velocity estimation provides this criterion but is nonreproducible and nonquantifiable while automatic methods (which are reproducible and quantifiable) will find just one out of many kinematically equivalent models and mostly one which is geologically not attractive. Application of geologic constraints in conjunction with inversion by Differential Semblance Optimization produces models that are both geologically appealing, kinematically correct and have a very good fit to observed data.

Versteeg, R.J.; Symes, W.W. [Rice Univ., Houston, TX (United States)

1994-12-31

160

Inversion Chromosomes  

Microsoft Academic Search

A number of findings revealed that chromosome inversions are more frequent than deduced from classical cytogenetic studies.\\u000a Indeed, some paracentric cryptic inversions have been found to be flanked by segmental duplications, either causing a Mendelian\\u000a disease owing to the interruption of specific genes at inversion breakpoints or being present in the normal population as\\u000a a polymorphism. In the latter case,

Orsetta Zuffardi; Roberto Ciccone; Sabrina Giglio; Tiziano Pramparo

161

Acceleration of k-Eigenvalue / Criticality Calculations using the Jacobian-Free Newton-Krylov Method  

SciTech Connect

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.

Dana Knoll; HyeongKae Park; Chris Newman

2011-02-01

162

Compactified Strings as Quantum Statistical Partition Function on the Jacobian Torus  

SciTech Connect

We show that the solitonic contribution of toroidally compactified strings corresponds to the quantum statistical partition function of a free particle living on higher dimensional spaces. In the simplest case of compactification on a circle, the Hamiltonian is the Laplacian on the 2g-dimensional Jacobian torus associated with the genus g Riemann surface corresponding to the string world sheet. T duality leads to a symmetry of the partition function mixing time and temperature. Such a classical-quantum correspondence and T duality shed some light on the well-known interplay between time and temperature in quantum field theory and classical statistical mechanics.

Matone, Marco; Pasti, Paolo; Shadchin, Sergey; Volpato, Roberto [Dipartimento di Fisica 'G. Galilei' and Istituto Nazionale di Fisica Nucleare, Universita di Padova, Via Marzolo, 8-35131 Padova (Italy)

2006-12-31

163

Inverse Functions  

NSDL National Science Digital Library

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.

Moore, Lang

164

Kinematics and the Driver  

ERIC Educational Resources Information Center

Presents an application of the formulas of kinematics to the real driving situation, involving motion at constant speed and deceleration. Suggests the problem be used as an example in class, a homework assignment, or a test item. (CC)

Palatnick, Barton

1974-01-01

165

Recovery Discontinuous Galerkin Jacobian-Free Newton-Krylov Method for All-Speed Flows  

SciTech Connect

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.

HyeongKae Park; Robert Nourgaliev; Vincent Mousseau; Dana Knoll

2008-07-01

166

An optimal resolved rate law for kinematically redundant manipulators  

NASA Technical Reports Server (NTRS)

The resolved rate law for a manipulator provides the instantaneous joint rates required to satisfy a given instantaneous hand motion. When the joint space has more degrees of freedom than the task space, the manipulator is kinematically redundant and the kinematic rate equations are underdetermined. These equations can be locally optimized, but the resulting pseudo-inverse solution has been found to cause large joint rates in some cases. A weighting matrix in the locally optimized (pseudo-inverse) solution is dynamically adjusted to control the joint motion as desired. Joint reach limit avoidance is demonstrated in a kinematically redundant planar arm model. The treatment is applicable to redundant manipulators with any number of revolute joints and to non-planar manipulators.

Bourgeois, B. J.

1987-01-01

167

An inverse dynamics approach to face animation Michel Pitermann1  

E-print Network

An inverse dynamics approach to face animation Michel Pitermann1 and Kevin G. Munhall1,2 1 inversion Received) 1 #12;Abstract Muscle-based models of the human face produce high quality animation) that permits the animation to be created from kinematic recordings of facial movements. Using a nonlinear

Paris-Sud XI, Université de

168

Visual servoing of robot manipulators -- Part 1: Projective kinematics  

SciTech Connect

Visual servoing of robot manipulators is a key technique where the appearance of an object in the image plane is used to control the velocity of the end-effector such that the desired position is reached in the scene. The vast majority of visual servoing methods proposed so far uses calibrated robots in conjunction with calibrated cameras. It has been shown that the behavior of visual control loops does not degrade too much in the presence of calibration errors. Nevertheless, camera and robot calibration are complex and time-consuming processes requiring special-purpose mechanical devices, such as theodolites and calibration jigs. In this paper, the authors, suggest formulating a visual servoing control loop in nonmetric space, which in this case amounts to the projective space in which a triangulation of the scene using an uncalibrated stereo rig is expressed. The major consequence of controlling the robot in nonmetric space rather than in Euclidean space is that both the robot's direct kinematic map and the robot's Jacobian matrix must be defined in this space as well. Finally, they provide a practical method to estimate the projective kinematic model and they describe some preliminary simulated experiments that use this nonmetric model to perform stereo-based servoing. Nevertheless, in-depth analysis of projective control will be the topic of a forthcoming paper.

Ruf, A.; Horaud, R.

1999-11-01

169

Microwave spectrum of the H2DO+ ion: Inversion-rotation transitions and inversion splitting  

NASA Astrophysics Data System (ADS)

Inversion-rotation spectral lines of the monodeuterated hydronium ion, H2DO+, have been observed by a source-modulation spectrometer in the millimeter- to submillimeter-wave region. The ion was generated by a hollow-cathode discharge in a gas mixture of H2O and D2O. Nine inversion-rotation lines were measured precisely for the lowest pair of inversion doublets in the frequency region from 210to720GHz. The measured lines were analyzed to derive rotational constants in the inversion-doublet states and inversion splitting. The inversion splitting in the ground state was determined to be 1215866(410)MHz, that is, 40.5569(137)cm-1, where the numbers in parentheses give probable uncertainties estimated from the Jacobian matrix of the assumed centrifugal distortion constants of the inversion-doublet states. The determined inversion splitting is off by -0.58cm-1 from the predicted value of 41.14cm-1 by Rayamäki et al. using high-order coupled cluster ab initio calculations [J. Chem. Phys. 118, 10929 (2003)], and by 0.039cm-1 from the observed value of 40.518(10)cm-1 by Dong and Nesbitt using high-resolution jet-cooled infrared spectroscopy [J. Chem. Phys. 125, 144311 (2006)] beyond the quoted uncertainty. The most astronomically important transition 000--10+ for the ortho species was measured at 673257.024(31)MHz, which could be used as a radioastronomical probe investigating interstellar chemistry of deuterium fractionation in space.

Furuya, Takashi; Saito, Shuji; Araki, Mitsunori

2007-12-01

170

Kinematic Self-Similarity  

E-print Network

Self-similarity in general relativity is briefly reviewed and the differences between self-similarity of the first kind and generalized self-similarity are discussed. The covariant notion of a kinematic self-similarity in the context of relativistic fluid mechanics is defined. Various mathematical and physical properties of spacetimes admitting a kinematic self-similarity are discussed. The governing equations for perfect fluid cosmological models are introduced and a set of integrability conditions for the existence of a proper kinematic self-similarity in these models is derived. Exact solutions of the irrotational perfect fluid Einstein field equations admitting a kinematic self-similarity are then sought in a number of special cases, and it is found that; (1) in the geodesic case the 3-spaces orthogonal to the fluid velocity vector are necessarily Ricci-flat and (ii) in the further specialisation to dust the differential equation governing the expansion can be completely integrated and the asymptotic properties of these solutions can be determined, (iii) the solutions in the case of zero-expansion consist of a class of shear-free and static models and a class of stiff perfect fluid (and non-static) models, and (iv) solutions in which the kinematic self-similar vector is parallel to the fluid velocity vector are necessarily Friedmann-Robertson-Walker (FRW) models.

A. A. Coley

1996-10-25

171

Kinematic control of robot with degenerate wrist  

NASA Technical Reports Server (NTRS)

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.

Barker, L. K.; Moore, M. C.

1984-01-01

172

Imaging Moving Targets from Scattered Waves This version includes a Jacobian that is missing in the version published in  

E-print Network

Imaging Moving Targets from Scattered Waves This version includes a Jacobian that is missing it specializes to familiar results in the cases when: a) the targets are moving slowly, b) the targets are far from the antennas, and c) narrowband waveforms are used. From these models, we develop a phase

Cheney, Margaret

173

Kinematic Bézier Maps.  

PubMed

The kinematics of a robot with many degrees of freedom is a very complex function. Learning this function for a large workspace with a good precision requires a huge number of training samples, i.e., robot movements. In this paper, we introduce the Kinematic Bézier Map (KB-Map), a parameterizable model without the generality of other systems but whose structure readily incorporates some of the geometric constraints of a kinematic function. In this way, the number of training samples required is drastically reduced. Moreover, the simplicity of the model reduces learning to solving a linear least squares problem. Systematic experiments have been carried out showing the excellent interpolation and extrapolation capabilities of KB-Maps and their relatively low sensitivity to noise. PMID:22481828

Ulbrich, Stefan; Ruiz de Angulo, Vicente; Asfour, Tamim; Torras, Carme; Dillmann, Rüdiger

2012-04-01

174

THE PHOTOMETRIC AND KINEMATIC STRUCTURE OF FACE-ON DISK GALAXIES. III. KINEMATIC INCLINATIONS FROM H{alpha} VELOCITY FIELDS  

SciTech Connect

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.

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

175

Kinematics: Speed, Velocity & Acceleration  

NSDL National Science Digital Library

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.

2010-01-01

176

Kinematics of deformable media  

NASA Astrophysics Data System (ADS)

We investigate the kinematics of deformations in two and three dimensional media by explicitly solving (analytically) the evolution equations (Raychaudhuri equations) for the expansion, shear and rotation associated with the deformations. The analytical solutions allow us to study the dependence of the kinematical quantities on initial conditions. In particular, we are able to identify regions of the space of initial conditions that lead to a singularity in finite time. Some generic features of the deformations are also discussed in detail. We conclude by indicating the feasibility and utility of a similar exercise for fluid and geodesic flows in a flat and curved spacetimes.

Dasgupta, Anirvan; Nandan, Hemwati; Kar, Sayan

2008-07-01

177

Kinematics of deformable media  

SciTech Connect

We investigate the kinematics of deformations in two and three dimensional media by explicitly solving (analytically) the evolution equations (Raychaudhuri equations) for the expansion, shear and rotation associated with the deformations. The analytical solutions allow us to study the dependence of the kinematical quantities on initial conditions. In particular, we are able to identify regions of the space of initial conditions that lead to a singularity in finite time. Some generic features of the deformations are also discussed in detail. We conclude by indicating the feasibility and utility of a similar exercise for fluid and geodesic flows in a flat and curved spacetimes.

Dasgupta, Anirvan [Department of Mechanical Engineering and Centre for Theoretical Studies, Indian Institute of Technology, Kharagpur 721 302 (India)], E-mail: anir@mech.iitkgp.ernet.in; Nandan, Hemwati [Centre for Theoretical Studies, Indian Institute of Technology, Kharagpur 721 302 (India)], E-mail: hnandan@cts.iitkgp.ernet.in; Kar, Sayan [Department of Physics and Centre for Theoretical Studies, Indian Institute of Technology, Kharagpur 721 302 (India)], E-mail: sayan@cts.iitkgp.ernet.in

2008-07-15

178

The Kinematic Analysis of a Symmetrical Three-Degree-of-Freedom Planar Parallel Manipulator  

E-print Network

Presented in this paper is the kinematic analysis of a symmetrical three-degree-of-freedom planar parallel manipulator. In opposite to serial manipulators, parallel manipulators can admit not only multiple inverse kinematic solutions, but also multiple direct kinematic solutions. This property produces more complicated kinematic models but allows more flexibility in trajectory planning. To take into account this property, the notion of aspects, i.e. the maximal singularity-free domains, was introduced, based on the notion of working modes, which makes it possible to separate the inverse kinematic solutions. The aim of this paper is to show that a non-singular assembly-mode changing trajectory exist for a symmetrical planar parallel manipulator, with equilateral base and platform triangle.

Chablat, Damien

2004-01-01

179

A fast nonrigid image registration with constraints on the Jacobian using large scale constrained optimization.  

PubMed

This paper presents a new nonrigid monomodality image registration algorithm based on B-splines. The deformation is described by a cubic B-spline field and found by minimizing the energy between a reference image and a deformed version of a floating image. To penalize noninvertible transformation, we propose two different constraints on the Jacobian of the transformation and its derivatives. The problem is modeled by an inequality constrained optimization problem which is efficiently solved by a combination of the multipliers method and the L-BFGS algorithm to handle the large number of variables and constraints of the registration of 3-D images. Numerical experiments are presented on magnetic resonance images using synthetic deformations and atlas based segmentation. PMID:18334448

Sdika, Michaël

2008-02-01

180

Jacobian and stiffness analysis of a novel class of six-DOF parallel minimanipulators  

SciTech Connect

The Jacobian and stiffness matrices of two types of novel, six-DOF parallel minimanipulators are derived. A minimanipulator consists of three inextensible limbs, each of which is driven by a two-DOF driver. Bilinear stepper motors are used as drivers in the first type minimanipulator, whereas five-bar linkages are used as drivers in the second type minimanipulator. All of the minimanipulator actuators are base-mounted. Inextensible limbs (and five-bar linkage drivers in the second type minimanipulator) improve positional resolution and stiffness of the minimanipulators in certain directions. It is shown that, at the central configuration, the stiffness matrix of the first type minimanipulator can be diagonalized (decoupled). It is also shown that the first type minimanipulator can be designed to possess direct or torsional isotropic stiffness properties. Moreover, guidelines for designing the drivers of the second type minimanipulator are established. 20 refs.

Tashmasebi, F. (National Aeronautics and Space Administration, Greenbelt, MD (United States). Goddard Space Flight Center); Tsai, Lung-Wen (Maryland Univ., College Park, MD (United States). Dept. of Mechanical Engineering)

1992-01-01

181

Jacobian and stiffness analysis of a novel class of six-DOF parallel minimanipulators  

SciTech Connect

The Jacobian and stiffness matrices of two types of novel, six-DOF parallel minimanipulators are derived. A minimanipulator consists of three inextensible limbs, each of which is driven by a two-DOF driver. Bilinear stepper motors are used as drivers in the first type minimanipulator, whereas five-bar linkages are used as drivers in the second type minimanipulator. All of the minimanipulator actuators are base-mounted. Inextensible limbs (and five-bar linkage drivers in the second type minimanipulator) improve positional resolution and stiffness of the minimanipulators in certain directions. It is shown that, at the central configuration, the stiffness matrix of the first type minimanipulator can be diagonalized (decoupled). It is also shown that the first type minimanipulator can be designed to possess direct or torsional isotropic stiffness properties. Moreover, guidelines for designing the drivers of the second type minimanipulator are established. 20 refs.

Tashmasebi, F. [National Aeronautics and Space Administration, Greenbelt, MD (United States). Goddard Space Flight Center; Tsai, Lung-Wen [Maryland Univ., College Park, MD (United States). Dept. of Mechanical Engineering

1992-08-01

182

Radiance and Jacobian Intercomparison of Radiative Transfer Models Applied to HIRS and AMSU Channels  

NASA Technical Reports Server (NTRS)

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.

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

183

Radiance and Jacobian Intercomparison of Radiative Transfer Models Applied to HIRS and AMSU Channels  

NASA Technical Reports Server (NTRS)

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.

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

184

Kinematics of Tape Recording.  

ERIC Educational Resources Information Center

Describes mathematics of the nonliner relationships between a constant-speed, capstan-driven magnetic tape transport mechanism and a constant-angular-velocity take-up reel. The relationship, derived from the sum of a partial, serves in recognition of a finite tape. Thickness can serve as an example of rotational kinematics. (Author/SK)

Coleman, J. J.

1982-01-01

185

Teaching about Kinematics  

ERIC Educational Resources Information Center

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…

Nelson, Jane Bray; Nelson, Jim

2009-01-01

186

Microwave spectrum of the HD2O+ ion: Inversion-rotation transitions and inversion splitting  

NASA Astrophysics Data System (ADS)

Inversion-rotation spectral lines of the dideuterated hydronium ion, HD2O +, have been observed by a source-modulation millimeter- to submillimeter-wave spectrometer. The ion was generated by a hollow-cathode discharge in a gas mixture of D2O and H2O in a free-space cell. Ten inversion-rotation lines were measured precisely for the lowest pair of inversion doublets in the frequency region from 380to730GHz. The observed lines include the most astronomically important transitions, 000--110+ for the para species at 380538.031(32)MHz and 101--111+ for the ortho species at 728420.189(34)MHz, which could be used as a radio astronomical probe investigating interstellar chemistry of deuterium fractionation. An analysis of the measured lines has yielded the rotational constants in the ground doublet states and the inversion splitting. The inversion splitting in the ground state was determined to be 808866(34)MHz, that is, 26.98087(113)cm-1, where the numbers in parentheses give uncertainties estimated from the Jacobian matrix of the assumed centrifugal distortion constants. The determined inversion splitting is off by -0.51cm-1 from the predicted value of 27.49cm-1 by Rajamäki et al. using high-order coupled cluster ab initio calculation [J. Chem. Phys. 118, 10929 (2003)], and by -0.0510cm-1 from the observed value of 27.0318(72)cm-1 by Dong et al. using high-resolution jet-cooled infrared spectroscopy [J. Chem. Phys. 122, 224301 (2005)] beyond the quoted uncertainty.

Furuya, Takashi; Saito, Shuji

2008-01-01

187

Measurements of neutron-induced reactions in inverse kinematics  

NASA Astrophysics Data System (ADS)

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.

Reifarth, René; Litvinov, Yuri A.

2014-01-01

188

Mesh Puppetry: Cascading Optimization of Mesh Deformation with Inverse Kinematics  

E-print Network

approach builds upon traditional rigging by optimizing skeleton position and vertex weights positions, balance of the character, length and rigidity preservation, joint limits, and/or self- collision- nipulated to deform the posture of a character, then skinning (or "binding") is used to match the fine

Desbrun, Mathieu

189

Task-Directed Inverse Kinematics For Redundant Manipulators  

NASA Technical Reports Server (NTRS)

Paper presents algorithms for use in controlling redundant robotic manipulators in such way as to exploit redundancy to satisfy task requirements beyond placement of end effectors at desired positions and orientations.

Long, Mark K.

1994-01-01

190

RESEARCH ARTICLE Freeing the serial mechanism designer from inverse kinematic  

E-print Network

of Washington, Seattle, WA, USA. The BioRobotics Lab's Raven surgical robot is designed for minimally invasive the patient. The advantages of a system like the Raven are more fully described by Lum et al (2006). The Bio the Raven over the patient and can be used for automatic tool changes. The com- bined Raven/C-Arm system

Rosen, Jacob

191

Kinematic Models for Design  

NSDL National Science Digital Library

For those who may have forgotten the lessons of kinematics from high school, it is the branch of classical mechanics that "describes the motion of points, bodies, and systems of bodies without consideration of the causes of motion." This remarkable digital collection from Cornell University brings together 50 critical books and articles that tell the history of this fascinating subject. Most of the materials here are from the 19th and early 20th centuries, and they include "Kennedy's Mechanics of Machinery" from 1886 and "Durley's Kinematics of Machines" from 1907. Visitors can search the entire collection by keyword and date. They can also download each volume for offline consideration, if they so desire. One item that should not be missed is Charles Babbage's seminal work "On a Method of Expressing by Signs The Action of Machinery".

2012-01-01

192

Hybrid conjugate gradient-Occam algorithms for inversion of multifrequency and multitransmitter EM data  

NASA Astrophysics Data System (ADS)

We describe novel hybrid algorithms for inversion of electromagnetic geophysical data, combining the computational and storage efficiency of a conjugate gradient approach with an Occam scheme for regularization and step-length control. The basic algorithm is based on the observation that iterative solution of the symmetric (Gauss-Newton) normal equations with conjugate gradients effectively generates a sequence of sensitivities for different linear combinations of the data, allowing construction of the Jacobian for a projection of the original full data space. The Occam scheme can then be applied to this projected problem, with the tradeoff parameter chosen by assessing fit to the full data set. For EM geophysical problems with multiple transmitters (either multiple frequencies or source geometries) an extension of the basic hybrid algorithm is possible. In this case multiple forward and adjoint solutions (one each for each transmitter) are required for each step in the iterative normal equation solver, and each corresponds to the sensitivity for a separate linear combination of data. From the perspective of the hybrid approach, with conjugate gradients generating an approximation to the full Jacobian, it is advantageous to save all of the component sensitivities, and use these to solve the projected problem in a larger subspace. We illustrate the algorithms on a simple problem, 2-D magnetotelluric inversion, using synthetic data. Both the basic and modified hybrid schemes produce essentially the same result as an Occam inversion based on a full calculation of the Jacobian, and the modified scheme requires significantly fewer steps (relative to the basic hybrid scheme) to converge to an adequate solution to the normal equations. The algorithms are expected to be useful primarily for 3-D inverse problems for which the computational burden is heavily dominated by solution to the forward and adjoint problems.

Egbert, Gary D.

2012-07-01

193

Theoretical studies of active power\\/angle sub-matrix in power flow Jacobian for power system analysis  

Microsoft Academic Search

Properties of the active power\\/angle sub-matrix in the power flow Jacobian for power system analysis are studied. The sub-matrix\\u000a is a dominant and irreducible matrix under very general conditions of power systems, so that it is invertible. Also the necessary\\u000a conditions for its singularity are given. These theoretical results can be used to clarify the ambiguous understanding of\\u000a the sub-matrix

Guo-yun Cao; Qing Zhang; T. S. Chung; Chen Chen

2008-01-01

194

Strategies to Enhance the Model Update in Regions of Weak Sensitivities for Use in Full Waveform Inversion  

NASA Astrophysics Data System (ADS)

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.

Nuber, André; Manukyan, Edgar; Maurer, Hansruedi

2014-05-01

195

Laplace-domain waveform inversion versus refraction-traveltime tomography  

NASA Astrophysics Data System (ADS)

Geophysicists and applied mathematicians have proposed a rich suite of long-wavelength velocity estimation algorithms to construct starting velocity models for subsequent pre-stack depth migration and inversion. Refraction-traveltime tomography derives subsurface velocity models from picked first-arrival traveltimes. In contrast, Laplace-domain waveform inversion recovers long-wavelength velocity structure using the weighted amplitudes of first and later arrivals. There are several implementations of first-arrival traveltime inversion, with most based on ray tracing, and some based on the damped monochromatic wave equation, which accurately represent simple and finite-frequency first arrivals. Computationally, Laplace-domain wavefield inversion is quite similar to refraction-traveltime tomography using damped monochromatic wavefield, but the objective functions used in inversion are radically different. As in classical ray trace-based traveltime inversion, the objective of refraction-traveltime tomography using damped monochromatic wavefield is to match the phase (traveltime) of the first arrival of each measured seismic trace. In contrast, the objective of Laplace-domain wavefield inversion is to match the weighted amplitudes of both first and later arrivals to the weighted amplitudes of the measured seismic trace. Principles of refraction-traveltime tomography were used to generate velocity models of the earth one century ago. Laplace-domain waveform inversion is a more recently introduced algorithm and has been less rigorously studied by the seismic research community, with many workers believing it be equivalent to finite-frequency first-arrival traveltime tomography. We show that Laplace-domain waveform inversion is both theoretically and empirically different from finite-frequency first-arrival traveltime tomography. Specifically, we examine the Jacobian (sensitivity) kernels used in the two inversion schemes to quantify the different sensitivities (and hence the inversion results) of the two methods. Analysing both surface responses and sensitivity results, we show that the Laplace-domain waveform inversion's sensitivity to later arrivals provides significantly improved resolution of deeper velocity structure than the first-arrival traveltime tomography. We demonstrate this capability using numerical inversion examples using a synthetic five-layer model and the synthetic BP benchmark model. Because of the similar algorithmic structure, Laplace-domain waveform inversion fits neatly as a starting velocity model pre-processing component of a larger (multi) frequency-domain wave equation inversion solution package.

Bae, Ho Seuk; Pyun, Sukjoon; Shin, Changsoo; Marfurt, Kurt J.; Chung, Wookeen

2012-07-01

196

The kinematometer--an integrated kinematic sensor for kinesiological measurements.  

PubMed

The calculation of human joint forces and moments during locomotion is usually based on the solution of the "inverse dynamics problem." A new approach, called the Integrated Kinematic Sensor (IKS) approach, is proposed. It combines measurements of position, linear acceleration and angular velocity, coupled with six degrees of freedom analysis of rigid body motion, for the purpose of deriving high quality link kinematics and joint loads (force and moment) estimates. The IKS approach is tested on an instrumented compound pendulum to simulate the swing of a lower limb segment. The results show a high degree of correlation between the loads estimated by the IKS and those directly measured by the instrumented joint. The approach is illustrated by studying the kinematic and dynamic variables of the human shank segment during normal walking. The results agree with the basic patterns reported in the literature, while adding new information on transients during heel strike and toe off. PMID:8445899

Wu, G; Ladin, Z

1993-02-01

197

Inverse Problem of Capillary Filling  

NASA Astrophysics Data System (ADS)

The inverse problem of capillary filling, as defined in this work, consists in determining the capillary radius profile from experimental data of the meniscus position l as a function of time t. This problem is central in diverse applications, such as the characterization of nanopore arrays or the design of passive transport in microfluidics; it is mathematically ill posed and has multiple solutions; i.e., capillaries with different geometries may produce the same imbibition kinematics. Here a suitable approach is proposed to solve this problem, which is based on measuring the imbibition kinematics in both tube directions. Capillary filling experiments to validate the calculation were made in a wide range of length scales: glass capillaries with a radius of around 150 ?m and anodized alumina membranes with a pores radius of around 30 nm were used. The proposed method was successful in identifying the radius profile in both systems. Fundamental aspects also emerge in this study, notably the fact that the l(t)?t1/2 kinematics (Lucas-Washburn relation) is not exclusive of uniform cross-sectional capillaries.

Elizalde, Emanuel; Urteaga, Raúl; Koropecki, Roberto R.; Berli, Claudio L. A.

2014-04-01

198

Speaker independent acoustic-to-articulatory inversion  

NASA Astrophysics Data System (ADS)

Acoustic-to-articulatory inversion, the determination of articulatory parameters from acoustic signals, is a difficult but important problem for many speech processing applications, such as automatic speech recognition (ASR) and computer aided pronunciation training (CAPT). In recent years, several approaches have been successfully implemented for speaker dependent models with parallel acoustic and kinematic training data. However, in many practical applications inversion is needed for new speakers for whom no articulatory data is available. In order to address this problem, this dissertation introduces a novel speaker adaptation approach called Parallel Reference Speaker Weighting (PRSW), based on parallel acoustic and articulatory Hidden Markov Models (HMM). This approach uses a robust normalized articulatory space and palate referenced articulatory features combined with speaker-weighted adaptation to form an inversion mapping for new speakers that can accurately estimate articulatory trajectories. The proposed PRSW method is evaluated on the newly collected Marquette electromagnetic articulography -- Mandarin Accented English (EMA-MAE) corpus using 20 native English speakers. Cross-speaker inversion results show that given a good selection of reference speakers with consistent acoustic and articulatory patterns, the PRSW approach gives good speaker independent inversion performance even without kinematic training data.

Ji, An

199

Kinematics and dynamics of a six-degree-of-freedom robot manipulator with closed kinematic chain mechanism  

NASA Technical Reports Server (NTRS)

This paper deals with a class of robot manipulators built based on the kinematic chain mechanism (CKCM). This class of CKCM manipulators consists of a fixed and a moving platform coupled together via a number of in-parallel actuators. A closed-form solution is derived for the inverse kinematic problem of a six-degre-of-freedom CKCM manipulator designed to study robotic applications in space. Iterative Newton-Raphson method is employed to solve the forward kinematic problem. Dynamics of the above manipulator is derived using the Lagrangian approach. Computer simulation of the dynamical equations shows that the actuating forces are strongly dependent on the mass and centroid of the robot links.

Nguyen, Charles C.; Pooran, Farhad J.

1989-01-01

200

Possible Supersymmetric Kinematics  

E-print Network

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.

Chao-Guang Huang; Lin Li

2014-09-19

201

Kinematic capability in the SVDS  

NASA Technical Reports Server (NTRS)

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.

Flanders, H. A.

1977-01-01

202

Efficient Inversion of Mult-frequency and Multi-Source Electromagnetic Data  

SciTech Connect

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.

Gary D. Egbert

2007-03-22

203

Kinematics control for a 6DOF space manipulator based on ARM processor and FPGA Coprocessor  

Microsoft Academic Search

Based on ARM processor and FPGA co-processor, kinematics control for a 6-DOF (degree of freedom) space manipulator is realized in this paper. The ARM processor uses AT91FR40162, which mainly takes charge of the tractory planning for the space manipulator. Meanwhile, using the CORDIC (Coordinate Rotation Digital Computer) algorithm, the forward and inverse kinematics computation of the space manipulator are implemented

Zheng Yili; Sun Hanxu; Jia Qingxuan; Shi Guozhen

2008-01-01

204

Comparison of the adjoint and influence coefficient methods for solving the inverse hyperthermia problem.  

PubMed

An adjoint formulation is derived and used to determine the elements in the Jacobian matrix associated with the inverse problem of estimating the blood perfusion and temperature fields during hyperthermia cancer treatments. This method and a previously developed influence coefficient method for obtaining that matrix are comparatively evaluated by solving a set of numerically simulated inverse hyperthermia problems. The adjoint method has the advantage of requiring fewer solutions of the bioheat transfer equation to estimate the Jacobian than does the influence coefficient method when the number of measurement sensors is significantly smaller than the number of unknown parameters. Thus, it could be a preferable method to use in hyperthermia applications where the number of sensors is strictly limited by patient considerations. However, the adjoint method requires that CPU time intensive convolutions be numerically evaluated. Comparisons of the performance of the adjoint formulation and the influence coefficient method show that, first, there is a critical ratio of the number of measurement sensors to the number of unknown parameters at which the CPU time per iteration required to calculate the Jacobian matrix is the same for both methods. The adjoint method is faster than the influence coefficient method only when the value of the ratio is less than that critical value. For the hyperthermia problems investigated in the present study, this only occurs for cases with a very small number of measurement sensors. This presents a potential problem for clinical applications because the fewer measurement sensors used, the less information that can be gathered to correctly solve the inverse problem.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8445900

Liauh, C T; Hills, R G; Roemer, R B

1993-02-01

205

Kinematics and control of a fully parallel force-reflecting hand controller for manipulator teleoperation  

NASA Technical Reports Server (NTRS)

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.

Bryfogle, Mark D.; Nguyen, Charles C.; Antrazi, Sami S.; Chiou, Peter C.

1993-01-01

206

Kinematics of Globular Cluster Systems  

E-print Network

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.

Aaron J. Romanowsky

2006-09-08

207

Joint inversion of acoustic and resistivity data for the estimation of gas hydrate concentration  

USGS Publications Warehouse

Downhole log measurements, such as acoustic or electrical resistivity logs, are frequently used to estimate in situ gas hydrate concentrations in the pore space of sedimentary rocks. Usually the gas hydrate concentration is estimated separately based on each log measurement. However, measurements are related to each other through the gas hydrate concentration, so the gas hydrate concentrations can be estimated by jointly inverting available logs. Because the magnitude of slowness of acoustic and resistivity values differs by more than an order of magnitude, a least-squares method, weighted by the inverse of the observed values, is attempted. Estimating the resistivity of connate water and gas hydrate concentration simultaneously is problematic, because the resistivity of connate water is independent of acoustics. In order to overcome this problem, a coupling constant is introduced in the Jacobian matrix. In the use of different logs to estimate gas hydrate concentration, a joint inversion of different measurements is preferred to the averaging of each inversion result.

Lee, Myung W.

2002-01-01

208

Statistic inversion of multi-zone transition probability models for aquifer characterization in alluvial fans  

E-print Network

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...

Zhu, Lin; Gong, Huili; Gable, Carl; Teatini, Pietro

2015-01-01

209

O-star kinematics  

SciTech Connect

Proper motions determined by the authors are utilized to study the kinematics of 79 O-type stars at distance r< or =2.5 kpc. The sample is divided into two groups, having space-velocity dispersions tau/sub I/roughly-equal10 km/sec, sigma/sub II/roughly-equal35 km/sec. Solutions for the velocity-field parameters for group I yield a galactic angular rotation speed ..omega../sub 0/ = 24.9 km sec/sup -1/ kpc/sup -1/ at the sun (for R/sub 0/ = 10.0 kpc) and an Oort constant A = 12.2 km sec/sup -1/ kpc/sup -1/. Most of the O stars exhibit a small z-velocity directed away from the galactic plane. The velocity-ellipsoid parameters and box-orbit elements are calculated.

Karimova, D.K.; Pavlovskaya, E.D.

1984-01-01

210

Kinematics of vector fields  

E-print Network

Different (not only by sign) affine connections are introduced for contravariant and covariant tensor fields over a differentiable manifold by means of a non-canonical contraction operator, defining the notion dual bases and commuting with the covariant and with the Lie-differential operator. Classification of the linear transports on the basis of the connections between the connections is given. Notion of relative velocity and relative acceleration for vector fields are determined. By means of these kinematic characteristics several other types of notions as shear velocity, shear acceleration, rotation velocity, rotation acceleration, expansion velocity and expansion acceleration are introduced and on their basis auto-parallel and non-isotropic (non-null) vector fields are classified.

S. Manoff

2000-03-02

211

Detailed solution to a complex kinematics chain manipulator  

SciTech Connect

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.

March-Leuba, S; Jansen, J F; Kress, R L; Babcock, S M

1992-01-01

212

Detailed solution to a complex kinematics chain manipulator  

SciTech Connect

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.

March-Leuba, S.; Jansen, J.F.; Kress, R.L.; Babcock, S.M.

1992-12-31

213

Robust Inversion and Data Compression in Control Allocation  

NASA Technical Reports Server (NTRS)

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).

Hodel, A. Scottedward

2000-01-01

214

Jacobian-free Newton Krylov discontinuous Galerkin method and physics-based preconditioning for nuclear reactor simulations  

SciTech Connect

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.

HyeongKae Park; Robert R. Nourgaliev; Richard C. Martineau; Dana A. Knoll

2008-09-01

215

Kinematics, controls, and path planning results for a redundant manipulator  

NASA Technical Reports Server (NTRS)

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.

Gretz, Bruce; Tilley, Scott W.

1989-01-01

216

Kinematic analysis of a flexible six-DOF parallel mechanism.  

PubMed

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

Jing, Feng-Shui; Tan, Min; Hou, Zeng-Guang; Liang, Zi-Ze; Wang, Yun-Kuan; Gupta, Madan M; Nikiforuk, Peter N

2006-04-01

217

Error analysis and optimization of a 3-degree of freedom translational Parallel Kinematic Machine  

NASA Astrophysics Data System (ADS)

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.

Shankar Ganesh, S.; Koteswara Rao, A. B.

2014-06-01

218

Ground reaction forces, kinematics, and muscle activations during the windmill softball pitch  

Microsoft Academic Search

The aims of the present study were to examine quantitatively ground reaction forces, kinematics, and muscle activations during the windmill softball pitch, and to determine relationships between knee valgus and muscle activations, ball velocity and muscle activation as well as ball velocity and ground reaction forces. It was hypothesized that there would be an inverse relationship between degree of knee

Gretchen D. Oliver; Hillary Plummer

2011-01-01

219

Effect of the Ankle Stabilizing Orthosis on Foot and Ankle Kinematics During Cutting Maneuvers  

Microsoft Academic Search

This study was to examine the stability and functionality of the Ankle Stabilizing Orthosis (ASO) in normal ankle kinematics during sideward and forward lateral cutting. Fifteen college students with normal ankles were randomly assigned to each of the following four conditions: sideward and forward lateral cutting, with and without the ASO. Ankle inversion–eversion and dorsiflexion–plantarflexion angular displacements and velocities during

Amisha Gudibanda; Yong “Tai” Wang

2005-01-01

220

IDMME 2006 Grenoble, France, May 17-19, 2006 KINEMATICAL PERFORMANCES IN 5-AXIS MACHINING  

E-print Network

. This model highlights differences between the programmed tool-path and the actual follow-up of the trajectory. Within the High Speed Machining context, kinematical limits of the couple CNC-machine-tool have to be taken into account in the model. The originality of the model is the use of the inverse-time method

Boyer, Edmond

221

Resolving the Redundancy of a Seven DOF Wearable Robotic System Based on Kinematic and Dynamic Constraint  

E-print Network

to the inverse kinematics. The redundancy of a wearable robotic system (exoskeleton) that interacts robots such as the wearable exoskeleton robot [1] directly interact with humans to enhance or support system (exoskeleton) such that it will be able to render motions as natural as that of the human arm

Rosen, Jacob

222

Kinematics of a New High Precision Three Degree-of-Freedom Parallel Manipulator  

NASA Technical Reports Server (NTRS)

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.

Tahmasebi, Farhad

2005-01-01

223

A global approach for using kinematic redundancy to minimize base reactions of manipulators  

NASA Technical Reports Server (NTRS)

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.

Chung, C. L.; Desa, S.

1989-01-01

224

Kinematics and dynamics of deployable structures with scissor-like-elements based on screw theory  

NASA Astrophysics Data System (ADS)

Because the deployable structures are complex multi-loop structures and methods of derivation which lead to simpler kinematic and dynamic equations of motion are the subject of research effort, the kinematics and dynamics of deployable structures with scissor-like-elements are presented based on screw theory and the principle of virtual work respectively. According to the geometric characteristic of the deployable structure examined, the basic structural unit is the common scissor-like-element(SLE). First, a spatial deployable structure, comprised of three SLEs, is defined, and the constraint topology graph is obtained. The equations of motion are then derived based on screw theory and the geometric nature of scissor elements. Second, to develop the dynamics of the whole deployable structure, the local coordinates of the SLEs and the Jacobian matrices of the center of mass of the deployable structure are derived. Then, the equivalent forces are assembled and added in the equations of motion based on the principle of virtual work. Finally, dynamic behavior and unfolded process of the deployable structure are simulated. Its figures of velocity, acceleration and input torque are obtained based on the simulate results. Screw theory not only provides an efficient solution formulation and theory guidance for complex multi-closed loop deployable structures, but also extends the method to solve dynamics of deployable structures. As an efficient mathematical tool, the simper equations of motion are derived based on screw theory.

Sun, Yuantao; Wang, Sanmin; Mills, James K.; Zhi, Changjian

2014-07-01

225

Globally convergent Jacobian-free nonlinear equation solvers based on non-monotone norm descent conditions and a modified line search technique  

Microsoft Academic Search

A Jacobian-free nonlinear equation solver based on a search technique called a ‘spiral search’, which is a modification of the line search, is proposed in this paper. Under mild conditions, the solver is proved to be globally convergent. The method is then extended to an overdetermined system of nonlinear equations. Numerical results show that for some problems, the solver outperforms

Shigeru Hanba

2010-01-01

226

KINEMATIC ANALYSIS OF MODULAR, TRUSS-BASED MANIPULATOR UNITS  

SciTech Connect

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.

Salerno, R. J.

1994-06-01

227

Kinematic performance analysis of a parallel-chain hexapod machine  

SciTech Connect

Inverse and forward kinematic models were derived to analyze the performance of a parallel-chain hexapod machine. Analytical models were constructed for both ideal and real structures. Performance assessment and enhancement algorithms were developed to determine the strut lengths for both ideal and real structures. The strut lengths determined from both cases can be used to analyze the effect of structural imperfections on machine performance. In an open-architecture control environment, strut length errors can be fed back to the controller to compensate for the displacement errors and thus improve the machine's accuracy in production.

Jing Song; Jong-I Mou; Calvin King

1998-05-18

228

A kinematic model of Kármán gaiting in rainbow trout  

PubMed Central

SUMMARY A mechanistic understanding of how fishes swim in unsteady flows is challenging despite its prevalence in nature. Previous kinematic studies of fish Kármán gaiting in a vortex street behind a cylinder only report time-averaged measurements, precluding our ability to formally describe motions on a cycle-by-cycle basis. Here we present the first analytical model that describes the swimming kinematics of Kármán gaiting trout with 70–90% accuracy. We found that body bending kinematics can be modelled with a travelling wave equation, which has also been shown to accurately model free-stream swimming kinematics. However, free-stream swimming and Kármán gaiting are separated in the parameter space; the amplitude, wavelength and frequency values of the traveling wave equation are substantially different for each behavior. During Kármán gaiting, the wave is initiated at the body center, which is 0.2L (where L is total body length) further down the body compared with the initiation point in free-stream swimming. The wave travels with a constant speed, which is higher than the nominal flow speed just as in free-stream swimming. In addition to undulation, we observed that Kármán gaiting fish also exhibit substantial lateral translations and body rotations, which can constitute up to 75% of the behavior. These motions are periodic and their frequencies also match the vortex shedding frequency. There is an inverse correlation between head angle and body angle: when the body rotates in one direction, the head of the fish turns into the opposite direction. Our kinematic model mathematically describes how fish swim in vortical flows in real time and provides a platform to better understand the effects of flow variations as well as the contribution of muscle activity during corrective motions. PMID:24115054

Akanyeti, Otar; Liao, James C.

2013-01-01

229

A kinematic model of Kármán gaiting in rainbow trout.  

PubMed

A mechanistic understanding of how fishes swim in unsteady flows is challenging despite its prevalence in nature. Previous kinematic studies of fish Kármán gaiting in a vortex street behind a cylinder only report time-averaged measurements, precluding our ability to formally describe motions on a cycle-by-cycle basis. Here we present the first analytical model that describes the swimming kinematics of Kármán gaiting trout with 70-90% accuracy. We found that body bending kinematics can be modelled with a travelling wave equation, which has also been shown to accurately model free-stream swimming kinematics. However, free-stream swimming and Kármán gaiting are separated in the parameter space; the amplitude, wavelength and frequency values of the traveling wave equation are substantially different for each behavior. During Kármán gaiting, the wave is initiated at the body center, which is 0.2L (where L is total body length) further down the body compared with the initiation point in free-stream swimming. The wave travels with a constant speed, which is higher than the nominal flow speed just as in free-stream swimming. In addition to undulation, we observed that Kármán gaiting fish also exhibit substantial lateral translations and body rotations, which can constitute up to 75% of the behavior. These motions are periodic and their frequencies also match the vortex shedding frequency. There is an inverse correlation between head angle and body angle: when the body rotates in one direction, the head of the fish turns into the opposite direction. Our kinematic model mathematically describes how fish swim in vortical flows in real time and provides a platform to better understand the effects of flow variations as well as the contribution of muscle activity during corrective motions. PMID:24115054

Akanyeti, Otar; Liao, James C

2013-12-15

230

Tracking lung tissue motion and expansion/compression with inverse consistent image registration and spirometry  

SciTech Connect

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.

Christensen, Gary E.; Song, Joo Hyun; Lu, Wei; Naqa, Issam El; Low, Daniel A. [Department of Electrical and Computer Engineering and Department of Radiation Oncology, University of Iowa, Iowa City, Iowa 52242 (United States); Department of Electrical and Computer Engineering, University of Iowa, Iowa City, Iowa 52242 (United States); Department of Radiation Oncology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110 (United States)

2007-06-15

231

Comparison of iterative methods and preconditioners for two-phase flow in porous media using exact and approximate Jacobians  

NASA Astrophysics Data System (ADS)

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.

Büsing, Henrik

2013-04-01

232

Emergent gravity requires kinematic nonlocality.  

PubMed

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

Marolf, Donald

2015-01-23

233

Emergent Gravity Requires Kinematic Nonlocality  

NASA Astrophysics Data System (ADS)

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.

Marolf, Donald

2015-01-01

234

H? Kinematics of KPG 390  

NASA Astrophysics Data System (ADS)

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.

Repetto, P.; Rosado, M.; Gabbasov, R.; Fuentes-Carrera, I.

2010-06-01

235

Kinematic Dexterity of Robotic Mechanisms  

Microsoft Academic Search

In this article we develop a mathematical theory for optimizing the kinematic dexterity of robotic mechanisms and obtain a collection of analytical tools for robot design. The performance criteria we consider are workspace volume and dexterity; by the latter we mean the ability to move and apply forces in arbitrary directions as easily as possible. Clearly, dexterity and workspace volume

Frank C. Park; Roger W. Brockett

1994-01-01

236

Kinematic Parameters of Signed Verbs  

ERIC Educational Resources Information Center

Purpose: Sign language users recruit physical properties of visual motion to convey linguistic information. Research on American Sign Language (ASL) indicates that signers systematically use kinematic features (e.g., velocity, deceleration) of dominant hand motion for distinguishing specific semantic properties of verb classes in production…

Malaia, Evie; Wilbur, Ronnie B.; Milkovic, Marina

2013-01-01

237

Development of kinematic equations and determination of workspace of a 6 DOF end-effector with closed-kinematic chain mechanism  

NASA Technical Reports Server (NTRS)

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.

Nguyen, Charles C.; Pooran, Farhad J.

1989-01-01

238

Kinematic Modeling of the 2004 Parkfield Earthquake  

NASA Astrophysics Data System (ADS)

Seismic waveform and GPS deformation data are combined to solve for the kinematic rupture process of the 2004 Parkfield earthquake. The observed acceleration from sites of the CISN arrays are integrated to displacement, and bandpass filtered between 0.01 to 0.3 Hz. The GPS coseismic displacements were determined from 2-hr interval averaged solutions assuming an offset and an exponential function fit to the postseismic displacements. In this study we determine the optimal orientation of a single rupture plane as constrained by the seismic and GPS data. Finite-source slip models will be presented for cases in which the seismic waveform and GPS data are inverted separately and together. The preliminary results show that the earthquake, which initiated 25 km SE of Middle Mountain, ruptured the 25 km of the fault to the NW filling in the region previously ruptured by the 1934 and 1966 Parkfield earthquakes. The 2004 event slip distribution appears to be complementary to that for the 1966 earthquake, and roughly covers the same area that slipped in the 1934 Parkfield event. There are three primary asperities. Two are deep (5 to 13 km) at the two ends of the rupture, and the third is shallow (2 to 5 km) in the middle of the rupture. This shallow asperity is not strong in the inversion results using just the seismic waveform data, and is primarily constrained by the near-fault GPS observations. The seismic waveform inversion yields a moment consistent with the seismic moment tensor result (9.97e24 dyne cm), while the addition of the GPS data tends to increase the moment by about 10-30% depending on seismic to GPS weight, smoothing parameters and the time interval used to determined the GPS vectors. It is possible that the 2-hr interval coseismic GPS solution contains a significant post-seismic signal. This will be investigated by comparing inversions using shorter interval GPS data. In 1994 a Mw 5.0 event occurred SW of Middle Mountain. This event also appears complementary to the 2004 rupture in the sense that there are low levels of slip in the region where the 1994 event occurred. The relationship between the 1994 and 2004 events in terms of dynamic rupture is investigated by using the 1994 stress change as initial conditions.

Dreger, D.; Murray, M. H.; Oglesby, D.

2004-12-01

239

HI in spiral galaxies Stellar kinematics  

E-print Network

Outline HI in spiral galaxies CO and H2 Stellar kinematics STRUCTURE OF GALAXIES 5. Kinematics of galaxies Piet van der Kruit Kapteyn Astronomical Institute University of Groningen the Netherlands February 2010 Piet van der Kruit, Kapteyn Astronomical Institute Kinematics of galaxies #12;Outline HI in spiral

Kruit, Piet van der

240

Influence of biological kinematics on abstract concept processing.  

PubMed

During a random number generation task, human beings tend to produce more small numbers than large numbers. However, this small number bias is modulated when motor behaviour, such as a turn of the head, is performed during the random number generation task. This result fits with the finding that number representation is linked to laterally oriented actions, with small- and large-magnitude numbers generally linked to movement towards the left or the right side of space, respectively. To test whether this number-space association is specific to human motor behaviours or extends to any type of laterally oriented movements, we assessed whether the presentation of biological or nonbiological leftward or rightward movement affected a subsequent random number generation task. Biological and nonbiological movements were obtained by varying the kinematic parameters of the movements. Biological kinematics represented the tangential velocity actually observed in a human pointing movement; nonbiological kinematics represented equivalent movements but with an inverse tangential velocity along the path. The results show that only the observation of biological movements induces a space-number bias whereas observing nonbiological movements does not. This finding is the first evidence of a link between a biological marker and the semantic representation of a concept as abstract as number. PMID:25219421

Badets, Arnaud; Bidet-Ildei, Christel; Pesenti, Mauro

2015-03-01

241

Analysis of a closed-kinematic chain robot manipulator  

NASA Technical Reports Server (NTRS)

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.

Nguyen, Charles C.; Pooran, Farhad J.

1988-01-01

242

Robust magnetotelluric inversion  

NASA Astrophysics Data System (ADS)

A robust magnetotelluric (MT) inversion algorithm has been developed on the basis of quantile-quantile (q-q) plotting with confidence band and statistical modelling of inversion residuals for the MT response function (apparent resistivity and phase). Once outliers in the inversion residuals are detected in the q-q plot with the confidence band and the statistical modelling with the Akaike information criterion, they are excluded from the inversion data set and a subsequent inversion is implemented with the culled data set. The exclusion of outliers and the subsequent inversion is repeated until the q-q plot is substantially linear within the confidence band, outliers predicted by the statistical modelling are unchanged from the prior inversion, and the misfit statistic is unchanged at a target level. The robust inversion algorithm was applied to synthetic data generated from a simple 2-D model and observational data from a 2-D transect in southern Africa. Outliers in the synthetic data, which come from extreme values added to the synthetic responses, produced spurious features in inversion models, but were detected by the robust algorithm and excluded to retrieve the true model. An application of the robust inversion algorithm to the field data demonstrates that the method is useful for data clean-up of outliers, which could include model as well as data inconsistency (for example, inability to fit a 2-D model to a 3-D data set), during inversion and for objectively obtaining a robust and optimal model. The present statistical method is available irrespective of the dimensionality of target structures (hence 2-D and 3-D structures) and of isotropy or anisotropy, and can operate as an external process to any inversion algorithm without modifications to the inversion program.

Matsuno, Tetsuo; Chave, Alan D.; Jones, Alan G.; Muller, Mark R.; Evans, Rob L.

2014-03-01

243

Contact kinematics of biomimetic scales  

NASA Astrophysics Data System (ADS)

Dermal scales, prevalent across biological groups, considerably boost survival by providing multifunctional advantages. Here, we investigate the nonlinear mechanical effects of biomimetic scale like attachments on the behavior of an elastic substrate brought about by the contact interaction of scales in pure bending using qualitative experiments, analytical models, and detailed finite element (FE) analysis. Our results reveal the existence of three distinct kinematic phases of operation spanning linear, nonlinear, and rigid behavior driven by kinematic interactions of scales. The response of the modified elastic beam strongly depends on the size and spatial overlap of rigid scales. The nonlinearity is perceptible even in relatively small strain regime and without invoking material level complexities of either the scales or the substrate.

Ghosh, Ranajay; Ebrahimi, Hamid; Vaziri, Ashkan

2014-12-01

244

Kinematic Fitting of Detached Vertices  

SciTech Connect

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.

Paul Mattione

2007-05-01

245

Pythagoras Theorem and Relativistic Kinematics  

NASA Astrophysics Data System (ADS)

In two inertial frames that move in a particular direction, may be registered a light signal that propagates in an angle with this direction. Applying Pythagoras theorem and principles of STR in both systems, we can derive all relativistic kinematics relations like the relativity of simultaneity of events, of the time interval, of the length of objects, of the velocity of the material point, Lorentz transformations, Doppler effect and stellar aberration.

Mulaj, Zenun; Dhoqina, Polikron

2010-01-01

246

Science of NHL Hockey: Kinematics  

NSDL National Science Digital Library

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.

NBC Learn

2010-10-07

247

Kinematic Characterization of Left Ventricular Chamber Stiffness and Relaxation  

NASA Astrophysics Data System (ADS)

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.

Mossahebi, Sina

248

Inverse Stochastic Linear Programming  

E-print Network

Keywords: Inverse Optimization, Stochastic Programming, Decomposition Algorithms ..... investment planning problem based on [16]. ... was supported by National Science Foundation grant CNS-0540000 from the Dynamic Data Driven.

2007-01-05

249

Inverse strategies for characterization of material properties  

NASA Astrophysics Data System (ADS)

The imaging of constitutive parameters is of interest in many science and engineering fields. Indeed, non-invasive and nondestructive techniques are used to characterize key properties of a system given its response due to an external excitation. Then, assuming a priori a given model of the system, the measured response and an inverse approach are used to identify material properties. This work was undertaken in the context of identification of spatially-varying elastic and viscoelastic parameters of solids using vibroacoustics based techniques. Two optimization approaches, nongradient and gradient-based optimization, were investigated in this work. Initially, nongradient-based algorithms were preferred over gradient-based algorithms because of there ability to find global minima irrespective of initial guesses. For instance, Gaussian radial basis functions were used to construct a finite-dimensional representation of the elastic moduli. Then, an inverse approach was used to approximate the spatiallyvarying elastic moduli through the system response induced by the radiation force of ultrasound. The inverse problem was cast as an optimization problem in which a least-square error functional that quantified the misfit between the experimental and finite element representation system response is minimized by searching over a space of admissible vectors that best describe the spatial distribution of the elastic moduli. Subsequently, gradient-based optimization was preferred over nongradient-based optimization as the number of design variables increased due to the increment in computational cost. Two inverse approaches, L2-adjoint and concept of error in constitutive equation, were investigated in the context of gradient-based optimization. First, the L2-adjoint inverse approach was used to characterize spatially-varying viscoelastic properties because of its advantage to efficiently calculate the gradient of the error functional with respect to the design variables by solving the corresponding adjoint equations. The inverse problem was cast as an optimization problem in which a least-square error functional that quantified the misfit between the experimental and the finite element representation system response is minimized by searching over a space of admissible functions that best describe the spatially-varying viscoelastic properties. Given that the least-square error functional is non-convex, an inverse approach based on the concept of error in constitutive equation was investigated. The convexity property of the error in constitutive equation functionals, shown extensively for elliptic boundary value problems, reduce the sensitivity of the inverse solution to parameter initialization. The inverse problem was cast as an optimization problem in which an error in constitutive equation functional that quantified the misfit between the kinematically and dynamically admissible stress fields is minimized by searching over a space of admissible functions that best describe the spatially-varying viscoelastic properties. Contrary to the L2-adjoint inverse approach, the gradient equation is easily derived by taking the direct derivative of the error in constitutive equation functional with respect to the design variables. The feasibility of the proposed inverse approaches is demonstrated through a series of numerical and physical experiments. Results show that the proposed inverse approaches have the potential to characterize spatially-varying elastic and viscoelastic properties of solids in realistic settings. Furthermore, it will be shown that the inverse approach based on the concept of error in constitutive equation outperformed the L2-adjoint inverse approach.

Aguilo, Miguel Alejandro

250

A parallel Jacobian-free Newton-Krylov solver for a coupled sea ice-ocean model  

NASA Astrophysics Data System (ADS)

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.

Losch, Martin; Fuchs, Annika; Lemieux, Jean-François; Vanselow, Anna

2014-01-01

251

Development of a sensor coordinated kinematic model for neural network controller training  

NASA Technical Reports Server (NTRS)

A robotic benchmark problem useful for evaluating alternative neural network controllers is presented. Specifically, it derives two camera models and the kinematic equations of a multiple degree of freedom manipulator whose end effector is under observation. The mapping developed include forward and inverse translations from binocular images to 3-D target position and the inverse kinematics of mapping point positions into manipulator commands in joint space. Implementation is detailed for a three degree of freedom manipulator with one revolute joint at the base and two prismatic joints on the arms. The example is restricted to operate within a unit cube with arm links of 0.6 and 0.4 units respectively. The development is presented in the context of more complex simulations and a logical path for extension of the benchmark to higher degree of freedom manipulators is presented.

Jorgensen, Charles C.

1990-01-01

252

Seismic Inversion Methods  

SciTech Connect

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.

Jackiewicz, Jason [New Mexico State University, Department of Astronomy, P.O. Box 30001, Las Cruces, NM 88003 (United States)

2009-09-16

253

Dewpoint temperature inversions analyzed  

NASA Technical Reports Server (NTRS)

Dewpoint temperature inversion, with regard to other simultaneous meteorological conditions, was examined to establish the influence of meteorological variables on the variation of dewpoint temperature with height. This report covers instrumentation and available data, all the climatological features of dewpoint inversions, and specific special cases.

Ashby, W. C.; Bogner, M. A.; Moses, H.

1969-01-01

254

Algebra Lab: Inverse Variation  

NSDL National Science Digital Library

This lesson from Algebra Lab demonstrates "how to write equations of quantities which vary inversely." The lesson includes an example of a graph of this type of equation, and several example problems. This supporting material would be best used following some in-class instruction explaining how to solve inverse variation equations.

2012-08-29

255

THE INVERSE CARE LAW  

Microsoft Academic Search

care tends to vary inversely with the need for it in the population served. This inverse care law operates more completely where medical care is most exposed to market forces, and less so where such exposure is reduced. The market distribution of medical care is a primitive and historically outdated social form, and any return to it would further exag-

JULIAN TUDOR HART

256

Inverse problems in space remote sensing: A sensitivity study on the atmospheres of Earth-like exoplanets  

NASA Astrophysics Data System (ADS)

More than one thousand exoplanets have been discovered in the past two decades, with some dozen of them in the host stars' habitable zone and with size and mass similar to Earth. Furthermore, spectra of exoplanets become available with reasonable quality (resolution and noise) that trigger the question of remote sensing of the planet's atmosphere. The objective of this sensitivity study is to identify the optimal state vector representing the atmosphere in the inverse problem. Solving the inverse problem will ultimately allow to characterize the planet and determine its habitability. Using a high resolution infrared radiative transfer code with a line-by-line molecular absorption model, we calculate synthetic spectra of exoplanets orbiting dwarf stars. Key parameters describing the atmosphere (i.e., molecular abundances, temperature, pressure) are identified and the Jacobians (i.e. partial derivatives of the spectra) are evaluated to investigate the feasibility to retrieve the state of the planetary atmosphere.

Vasquez, M.; Schreier, F.; Gimeno Garcia, S.; Hedelt, P.; Trautmann, T.

2014-04-01

257

Kinematics Control for a 7DOF Cable-Driven Anthropomorphic Arm  

Microsoft Academic Search

Based on the current research results of anthropomorphic-arm bionics and parallel manipulators, a motion control approach for a 7-DOF cable-driven manipulator is proposed. This paper introduces mechanical structure design of this anthropomorphic-arm first. For the inverse kinematics of the 7-DOF manipulator, a hybrid algorithm, based on gradient projection method and Paden-Kahan sub problems, is proposed to make the trajectory tracing

Weihai Chen; Quanzhu Chen; Jianbin Zhang; Shouqian Yu

2006-01-01

258

Large-scale hydraulic tomography and joint inversion of head and tracer data using the Principal Component Geostatistical Approach (PCGA)  

NASA Astrophysics Data System (ADS)

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.

Lee, J.; Kitanidis, P. K.

2014-07-01

259

Kinematic correction for roller skewing  

NASA Technical Reports Server (NTRS)

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.

Savage, M.; Loewenthal, S. H.

1980-01-01

260

Kinematic, workspace and singularity analysis of a new parallel robot used in minimally invasive surgery  

NASA Astrophysics Data System (ADS)

In the last ten years, due to development in robotic assisted surgery, the minimally invasive surgery has greatly changed. Until now, the vast majority of robots used in surgery, have serial structures. Due to the orientation parallel module, the structure is able to reduce the pressure exerted on the entrance point in the patient's abdominal wall. The parallel robot can also handle both a laparoscope as well an active instrument for different surgical procedures. The advantage of this parallel structure is that the geometric model has been obtained through an analytical approach. The kinematic modelling of a new parallel architecture, the inverse and direct geometric model and the inverse and direct kinematic models for velocities and accelerations are being determined. The paper will demonstrate that with this parallel structure, one can obtain the necessary workspace required for a minimally invasive operation. The robot workspace was generated using the inverse geometric model. An indepth study of different types of singularity is performed, allowing the development of safe control algorithms of the experimental model. Some kinematic simulation results and the experimental model of the robot are presented in the paper.

Stoica, Alin; Pisla, Doina; Andras, Szilaghyi; Gherman, Bogdan; Gyurka, Bela-Zoltan; Plitea, Nicolae

2013-03-01

261

Kinematics of primate midfoot flexibility.  

PubMed

This study describes a unique assessment of primate intrinsic foot joint kinematics based upon bone pin rigid cluster tracking. It challenges the assumption that human evolution resulted in a reduction of midfoot flexibility, which has been identified in other primates as the "midtarsal break." Rigid cluster pins were inserted into the foot bones of human, chimpanzee, baboon, and macaque cadavers. The positions of these bone pins were monitored during a plantarflexion-dorsiflexion movement cycle. Analysis resolved flexion-extension movement patterns and the associated orientation of rotational axes for the talonavicular, calcaneocuboid, and lateral cubometatarsal joints. Results show that midfoot flexibility occurs primarily at the talonavicular and cubometatarsal joints. The rotational magnitudes are roughly similar between humans and chimps. There is also a similarity among evaluated primates in the observed rotations of the lateral cubometatarsal joint, but there was much greater rotation observed for the talonavicular joint, which may serve to differentiate monkeys from the hominines. It appears that the capability for a midtarsal break is present within the human foot. A consideration of the joint axes shows that the medial and lateral joints have opposing orientations, which has been associated with a rigid locking mechanism in the human foot. However, the potential for this same mechanism also appears in the chimpanzee foot. These findings demonstrate a functional similarity within the midfoot of the hominines. Therefore, the kinematic capabilities and restrictions for the skeletal linkages of the human foot may not be as unique as has been previously suggested. PMID:25234343

Greiner, Thomas M; Ball, Kevin A

2014-12-01

262

Robust adaptive kinematic control of redundant robots  

NASA Technical Reports Server (NTRS)

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.

Tarokh, M.; Zuck, D. D.

1992-01-01

263

The role of reversed kinematics and double kinematic solutions in nuclear reactions studies  

Microsoft Academic Search

The advantages of reversed kinematics in nuclear reactions studies are discussed, with particular emphasis on the origin of double solutions in the reaction kinematics. This possibility for double solutions does not exist in normal kinematics, and provides the basis for a new method of imposing important experimental constraints on the uniqueness of fitting complex observations. By gating on one or

Morton Kaplan; Winifred E. Parker; David J. Moses; Roy Lacey; John M. Alexander

1993-01-01

264

An improved solution to the inverse dynamics of the general Stewart platform  

Microsoft Academic Search

This research presents an improved solution to the inverse kinematics and dynamics of the general Stewart platform. The dynamic equations are generated through Newton­ Euler approach. There have been a number of previous researches on this subject, but most of them consisted of some simplifying approximations which facilitate the formulation. Considering the creativity of the Newton-Euler method in the previous

S. Pedranunehr; M. Mahboubkhah; S. Pakzad

2011-01-01

265

Resonances and inverse scattering  

NASA Astrophysics Data System (ADS)

Inverse scattering problems for Sturm-Liouville differential equations find numerous applications in physics, in particular, quantum mechanics. While the theory of these problems has been developed over a number of decades, a more recent concern has been the use of resonances, important phenomena in physics, as data---the inverse resonance problem. In this dissertation, we address this problem in a variety of cases. First, we investigate the full-line Schrodinger equation where the data for the inverse problem include the eigenvalues and resonances. We prove that any two potentials that have enough data points sufficiently close together must also be close in a suitable sense. We then prove a discrete analogue for a full-line Jacobi equation. Finally, we prove a uniqueness theorem for a left-definite, half-line Sturm-Liouville equation. Along the way, we improve upon the current inverse spectral and scattering theorems for this equation.

Bledsoe, Matthew B.

266

Geological Inverse Theory Resources  

NSDL National Science Digital Library

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.

Ganse, Andrew A.

267

Inverse problems in electromagnetics  

E-print Network

Two inverse problems in electromagnetics are investigated in this thesis. The first is the retrieval of the effective constitutive parameters of metamaterials from the measurement of the reflection and the transmission ...

Chen, Xudong, 1977-

2005-01-01

268

Speeding up the learning of robot kinematics through function decomposition.  

PubMed

The main drawback of using neural networks or other example-based learning procedures to approximate the inverse kinematics (IK) of robot arms is the high number of training samples (i.e., robot movements) required to attain an acceptable precision. We propose here a trick, valid for most industrial robots, that greatly reduces the number of movements needed to learn or relearn the IK to a given accuracy. This trick consists in expressing the IK as a composition of learnable functions, each having half the dimensionality of the original mapping. Off-line and on-line training schemes to learn these component functions are also proposed. Experimental results obtained by using nearest neighbors and parameterized self-organizing map, with and without the decomposition, show that the time savings granted by the proposed scheme grow polynomially with the precision required. PMID:16342491

Ruiz de Angulo, Vicente; Torras, Carme

2005-11-01

269

The inverse electroencephalography pipeline  

NASA Astrophysics Data System (ADS)

The inverse electroencephalography (EEG) problem is defined as determining which regions of the brain are active based on remote measurements recorded with scalp EEG electrodes. An accurate solution to this problem would benefit both fundamental neuroscience research and clinical neuroscience applications. However, constructing accurate patient-specific inverse EEG solutions requires complex modeling, simulation, and visualization algorithms, and to date only a few systems have been developed that provide such capabilities. In this dissertation, a computational system for generating and investigating patient-specific inverse EEG solutions is introduced, and the requirements for each stage of this Inverse EEG Pipeline are defined and discussed. While the requirements of many of the stages are satisfied with existing algorithms, others have motivated research into novel modeling and simulation methods. The principal technical results of this work include novel surface-based volume modeling techniques, an efficient construction for the EEG lead field, and the Open Source release of the Inverse EEG Pipeline software for use by the bioelectric field research community. In this work, the Inverse EEG Pipeline is applied to three research problems in neurology: comparing focal and distributed source imaging algorithms; separating measurements into independent activation components for multifocal epilepsy; and localizing the cortical activity that produces the P300 effect in schizophrenia.

Weinstein, David Michael

270

Original article Kinematic study of the locomotion  

E-print Network

Original article Kinematic study of the locomotion of two crossbreds of lambs A Abourachid1 E of kinematics for measuring locomotive abil- ities of two lamb crossbreds, bred for meat production (Berrichons ground and jumping from an uphill slope. In order to observe their locomotive strategy, animals were free

Paris-Sud XI, Université de

271

Quantization of Kinematics on Configuration Manifolds1  

Microsoft Academic Search

The review is devoted to topological global aspects of quantal description. The treat- ment concentrates on quantizations of kinematical observables — generalized positions and momenta. A broad class of quantum kinematics is rigorously constructed for sys- tems, the configuration space of which is either a homogeneous space of a Lie group or a connected smooth finite-dimensional manifold without boundary. The

H.-D. Doebner

272

Quantization of Kinematics on Configuration Manifolds  

Microsoft Academic Search

This review paper is devoted to topological global aspects of quantal description. The treatment concentrates on quantizations of kinematical observables - generalized positions and momenta. A broad class of quantum kinematics is rigorously constructed for systems, the configuration space of which is either a homogeneous space of a Lie group or a connected smooth finite-dimensional manifold without boundary. The class

H.-D. Doebner; P. Stovícek; J. Tolar

2001-01-01

273

Target tracking problems subject to kinematic constraints  

Microsoft Academic Search

Filtering problems with kinematic constraints which may arise in target tracking problems are considered. A novel approach which treats kinematic constraints as additional fictitious or pseudomeasurements is proposed. A numerical example is provided to show the technical feasibility of the proposed idea for target tracking problems. This example shows that the proposed method can improve estimation accuracy significantly for velocity

MINJEA TAHK; JASON L. SPEYER

1990-01-01

274

Peripheral arterial disease affects kinematics during walking  

Microsoft Academic Search

Objective: Claudication is the most common manifestation of peripheral arterial disease (PAD) producing significant ambulatory compromise. The purpose of this study was to use advanced biomechanical analysis to characterize the kinematic ambulatory pattern of claudicating patients. We hypothesized that compared with control subjects, claudicat- ing patients have altered kinematic gait patterns that can be fully characterized utilizing advanced biomechanical analysis.

Rolando Celis; Iraklis I. Pipinos; Melissa M. Scott-Pandorf; Sara A. Myers; Jason M. Johanning

2008-01-01

275

Kinematics of the free throw in basketball  

NASA Astrophysics Data System (ADS)

The kinematics of the two basic styles of free throw in basketball are discussed. It is shown that from a purely kinematic and trajectory point of view, the overhand push shot is preferable to the underhand loop shot. The advantages of the underhand shot lie in the actual execution of the shot.

Tan, A.; Miller, G.

1981-06-01

276

Kinematics of the free throw in basketball  

Microsoft Academic Search

The kinematics of the two basic styles of free throw in basketball are discussed. It is shown that from a purely kinematic and trajectory point of view, the overhand push shot is preferable to the underhand loop shot. The advantages of the underhand shot lie in the actual execution of the shot.

A. Tan; G. Miller

1981-01-01

277

Philippine fault: A key for Philippine kinematics  

Microsoft Academic Search

On the basis of new geologic data and a kinematic analysis, we establish a simple kinematic model in which the motion between the Philippine Sea plate and Eurasia is distributed on two boundaries: the Philippine Trench and the Philippine fault. This model predicts a velocity of 2 to 2.5 cm\\/yr along the fault. Geologic data from the Visayas provide an

E. Barrier; P. Huchon; M. Aurelio

1991-01-01

278

Control Algorithms For Kinematically Redundant Manipulators  

NASA Technical Reports Server (NTRS)

Report presents improved algorithms for controlling kinematically redundant robotic manipulators, producing unique configuration for each end-effector location. Furthermore, they generally produce configurations in which no interference between robot boom and payload or base structures. Report presents comparison between various other robot-kinematic algorithms.

Wegner, David R.

1995-01-01

279

Analysis of kinematic invariances of multijoint reaching movement.  

PubMed

There is a no unique relationship between the trajectory of the hand, represented in cartesian or extrinsic space, and its trajectory in joint angle or intrinsic space in the general condition of joint redundancy. The goal of this work is to analyze the relation between planning the trajectory of a multijoint movement in these two coordinate systems. We show that the cartesian trajectory can be planned based on the task parameters (target coordinates, etc.) prior to and independently of angular trajectories. Angular time profiles are calculated from the cartesian trajectory to serve as a basis for muscle control commands. A unified differential equation that allows planning trajectories in cartesian and angular spaces simultaneously is proposed. Due to joint redundancy, each cartesian trajectory corresponds to a family of angular trajectories which can account for the substantial variability of the latter. A set of strategies for multijoint motor control following from this model is considered; one of them coincides with the frog wiping reflex model and resolves the kinematic inverse problem without inversion. The model trajectories exhibit certain properties observed in human multijoint reaching movements such as movement equifinality, straight end-point paths, bell-shaped tangential velocity profiles, speed-sensitive and speed-insensitive movement strategies, peculiarities of the response to double-step targets, and variations of angular trajectory without variations of the limb end-point trajectory in cartesian space. In humans, those properties are almost independent of limb configuration, target location, movement duration, and load. In the model, these properties are invariant to an affine transform of cartesian space. This implies that these properties are not a special goal of the motor control system but emerge from movement kinematics that reflect limb geometry, dynamics, and elementary principles of motor control used in planning. All the results are given analytically and, in order to compare the model with experimental results, by computer simulations. PMID:7578472

Goodman, S R; Gottlieb, G L

1995-09-01

280

Kinematic model of southern California  

SciTech Connect

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.

Weldon, R.; Humphreys, E.

1986-02-01

281

Kinematics of Andromeda's Stellar Disk  

NASA Astrophysics Data System (ADS)

The Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo (SPLASH) survey has so far measured radial velocities of over 10,000 individual bright stars in the inner 20 kpc of the Andromeda galaxy with the Keck/DEIMOS multiobject spectrograph. The survey samples disk populations of a variety of ages: young, massive main sequence and supergiant stars, intermediate-age AGB objects, and older red giant branch stars. Complementing this extensive dataset are velocity fields of the ionized gas from the same Keck/DEIMOS survey and neutral HI from the literature. We compare the kinematical structure of the old stellar, young stellar, neutral gas and ionized gas disks, measuring the relative velocity dispersions and rotation velocity lags. We discuss the evidence for thin, thick and kicked-up stellar disk components.

Dorman, Claire; Guhathakurta, P.; PHAT Collaboration; SPLASH Collaboration

2014-01-01

282

Cold atoms by kinematic cooling  

SciTech Connect

We report the preparation and observation of translationally cold atoms using kinematic cooling. In these experiments, krypton atoms are cooled to subkelvin temperatures by elastic collisions in crossed atomic beams. Two independent velocity measurements indicate an upper-bound mean velocity of 13 m/s (E{sub trans}/k=850 mK) and are consistent with a much lower mean velocity of 4 m/s (E{sub trans}/k=80 mK) (k is Boltzmann's constant). The density of the cold atoms is measured to be 10{sup 9} atoms/cm{sup 3}. Scattering calculations and diffusion models support these velocity and density measurements. The results demonstrate that cold, dense samples of ground-state atoms and molecules can be prepared by elastic collisions between identical collision partners.

Kay, Jeffrey J.; Strecker, Kevin E.; Chandler, David W. [Sandia National Laboratories, Livermore, California 94550 (United States); Klos, Jacek; Alexander, Millard H. [University of Maryland, College Park, Maryland 20742 (United States)

2010-09-15

283

Chromospherically young, kinematically old stars  

E-print Network

We have investigated a group of stars known to have low chromospheric ages, but high kinematical ages. Isochrone, chemical and lithium ages are estimated for them. The majority of stars in this group show lithium abundances much smaller than expected for their chromospheric ages, which is interpreted as an indication of their old age. Radial velocity measurements in the literature also show that they are not close binaries. The results suggest that they can be formed from the coalescence of short-period binaries. Coalescence rates, calculated taking into account several observational data and a maximum theoretical time scale for contact, in a short-period pair, predict a number of coalesced stars similar to what we have found in the solar neighbourhood.

H. J. Rocha-Pinto; B. V. Castilho; W. J. Maciel

2001-12-19

284

Water vapor and temperature inversions near the 0 deg C level over the tropical western Pacific. Master's thesis  

SciTech Connect

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.

Hart, K.A.

1994-01-01

285

Non-linear traveltime inversion for 3-D seismic tomography in strongly anisotropic media  

NASA Astrophysics Data System (ADS)

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.

Zhou, Bing; Greenhalgh, Stewart

2008-01-01

286

On the geometrical representation of the path integral reduction Jacobian: The case of dependent coordinates in the description of the reduced motion  

E-print Network

The geometrical representation of the path integral reduction Jacobian obtained in the problem of the path integral quantization of a scalar particle motion on a smooth compact Riemannian manifold with the given free isometric action of the compact semisimple Lie group has been found for the case when the local reduced motion is described by means of dependent coordinates. The result is based on the scalar curvature formula for the original manifold which is viewed as a total space of the principal fibre bundle.

S. N. Storchak

2008-10-31

287

Inverting Source Time Functions to determine the fault kinematic characteristics  

NASA Astrophysics Data System (ADS)

In seismology, the analisys of source kinematic parameters (slip-rate and rupture velocity ecc.) is a fundamental way to study the time-history of the rupture process that occurs during a seismic event. To this end various method to reconstruct source kinematics models from the inversion of seismogram have been proposed during the time. In this work we present an alternative methodology to infer source models. We aim, indeed, at obtaining the slip and rupture velocity distribution on the fault plane inverting the apparent Source Time Functions (STFs). This kind of analysis, rather than a classical inversion based on a direct study of seismograms recorded at various stations, may have several advantages. A major advantage is related to the possibility to overcome in the forward modeling any problem related to the computation of the Green's function, as the choice of the correct and reliable propagation model. To retrieve reliable STF, we apply the stabilized deconvolution technique proposed by Vallée [2004]. Based on Empirical Green's Functions (EGF) approach, this technique integrates in the deconvolution process four physical constraints on the STFs, that are causality, positivity, limited duration, and equal area. In any case the EGF approach suffers from certain limitations related to the selection of valuable Empirical Green Function, especially for small events. The approach used to invert the STFs is based on the technique of Emolo and Zollo [2005] to invert strong-motion data. In particular, the slip and the rupture velocity values are specified only at a set of control-points on the fault plane and their distributions on the whole fault are then obtained by a bicubic interpolation. The final slip and rupture velocity values at the fault-grid nodes are then determined by searching for the maximum of a fitness function (based of comparison between real and synthetic STFs) by using the Genetic Algorithm. The number of control-points is progressively increased to move from a high- to low-wavelength description of kinematic parameters on the fault. The optimal model parameter set is chosen according to Akaike Information Criterion [1974]. We present results for some synthetic tests and an application to a seismic events occurred during the 2009 L'Aquila (Central Italy) seismic sequence. In particular, we analyzed a small aftershock occurred on 2009 April 9, at 04:43:09 (UTC) characterized by a seismic moment of 1.07e+15 Nm (Mw 4). We found: a slip distribution, with an average value of 0.8 cm, characterized by a main slip patch located NW of the hypocenter and a rupture velocity distribution (mean value of 2.3 km/s) with a strong acceleration in the same direction.

Toraldo Serra, E. M.; Orefice, A.; Emolo, A.; Zollo, A.

2012-04-01

288

Non-linear inverse scattering: High resolution quantitative breast tissue tomography  

PubMed Central

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

Wiskin, J.; Borup, D. T.; Johnson, S. A.; Berggren, M.

2012-01-01

289

Non-linear inverse scattering: high resolution quantitative breast tissue tomography.  

PubMed

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

Wiskin, J; Borup, D T; Johnson, S A; Berggren, M

2012-05-01

290

Can a pseudo-dynamic source inversion approach improve earthquake source imaging?  

NASA Astrophysics Data System (ADS)

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.

Zhang, Youbing; Song, Seok Goo; Dalguer, Luis; Clinton, John

2014-05-01

291

Non-recursive augmented Lagrangian algorithms for the forward and inverse dynamics of constrained flexible multibodies  

NASA Technical Reports Server (NTRS)

A technique is presented for solving the inverse dynamics of flexible planar multibody systems. This technique yields the non-causal joint efforts (inverse dynamics) as well as the internal states (inverse kinematics) that produce a prescribed nominal trajectory of the end effector. A non-recursive global Lagrangian approach is used in formulating the equations for motion as well as in solving the inverse dynamics equations. Contrary to the recursive method previously presented, the proposed method solves the inverse problem in a systematic and direct manner for both open-chain as well as closed-chain configurations. Numerical simulation shows that the proposed procedure provides an excellent tracking of the desired end effector trajectory.

Bayo, Eduardo; Ledesma, Ragnar

1993-01-01

292

Integrating the Jacobian equation  

E-print Network

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 $P$.

Airton von Sohsten de Medeiros; Ráderson Rodrigues da Silva

2014-09-16

293

Kinematics of normal lingual diadokokinesis  

NASA Astrophysics Data System (ADS)

Speech-language clinicians use diadochokinetic (DDK) tasks as a behavioral measure of the status of the speech production system. The articulator kinematics of these repetitive syllable productions has been relatively little studied (most studies of speech DDK have been acoustic). As a result, many clinicians misunderstand the relationship between syllable rate and movement parameters, such as rate of articulator movement and range of articulator movement. For example, clinicians assume that because ``kuh'' syllable repetitions are relatively slow, tongue dorsum movements must be slow. However, Westbury and Dembowski [Ann. Bull. RILP No. 27 (1993)] showed that the tongue dorsum may produce larger and faster movements than other tongue points (such as the tongue tip). Therefore, syllable repetition rates may not reflect movement speeds for individual articulator points. This study replicates and extends these findings, using a larger speaker sample encompassing a wider age range. The goal of this study is to further clarify the relationship between articulator speed, range of articulator motion, and syllable rate. That is, it seeks to examine whether syllable rate is related to how quickly the tongue moves or how far the tongue moves. Data are derived from the University of Wisconsin X-ray Microbeam Database.

Flanagan, Kevin P.; Dembowski, James S.

2002-05-01

294

Edge-driven microplate kinematics  

USGS Publications Warehouse

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.

Schouten, Hans; Klitgord, Kim D.; Gallo, David G.

1993-01-01

295

Inverses and Elementary Matrices  

NSDL National Science Digital Library

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.

Smith, David

296

Inversion of perturbation series  

E-print Network

We investigate the inversion of perturbation series and its resummation, and prove that it is related to a recently developed parametric perturbation theory. Results for some illustrative examples show that in some cases series reversion may improve the accuracy of the results.

Paolo Amore; Francisco M. Fernandez

2007-10-25

297

Optimal kinematics and morphologies for spermatozoa  

E-print Network

We investigate the role of hydrodynamics in the evolution of the morphology and the selection of kinematics in simple uniflagellated microorganisms. We find that the most efficient swimming strategies are characterized by ...

Tam, Daniel See-Wai

298

DEPLOYABLE ANTENNA KINEMATICS USING TENSEGRITY STRUCTURE DESIGN  

E-print Network

DEPLOYABLE ANTENNA KINEMATICS USING TENSEGRITY STRUCTURE DESIGN By BYRON FRANKLIN KNIGHT This research has been a labor of love, beginning with my first job as a "new grad" building deployable antenna .........................................................................................................5 Tensegrity Overview

Florida, University of

299

Linking Synchronized Flow and Kinematic Waves  

Microsoft Academic Search

This paper shows that including the effects of lane-changing activity in kinematic wave theory reveals the physical mechanisms\\u000a and reproduces the main empirical features that motivated Kerner’s three-phase theory. This is shown using a hybrid representation\\u000a of traffic flow where lane-changing vehicles are treated as discrete particles with realistic accelerations embedded in a\\u000a continuous multilane kinematic wave stream. We show

Jorge A. Laval

300

Uncertainty Quantification in Finite-Fault Earthquake Source Inversions: The SIV project  

NASA Astrophysics Data System (ADS)

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.

Mai, P. M.; Gallovic, F.

2013-12-01

301

Aberrant pelvis and hip kinematics impair hip loading before and after total hip replacement.  

PubMed

Musculoskeletal loading is an important factor affecting the development of osteoarthritis, bone remodelling and primary fixation of total hip replacement (THR). In this study, we analyzed the relation between muscular force, gait kinematics and kinetics and hip loading in 20 patients before and six weeks after THR. Hip contact forces were calculated from gait analysis data using musculoskeletal modelling, inverse dynamics and static optimization. We found aberrant pelvis and hip kinematics and kinetics before and six weeks after surgery, confirming previous findings in literature. Furthermore, we found a decrease in the total contact force and its vertical component. These changes result in a decrease of the associated inclination angles of the total hip contact force in the sagittal and transverse planes, changing the orientation towards more vertical implant loading after THR. These changes in hip loading were related to observed gait kinematics and kinetics. Most importantly, excessive pelvic obliquity and associated hip adduction related to impaired implant loading. We concluded, therefore, that physical therapy in the early post-operative phase should primarily focus on stretching of anterior and medial structures and strengthening of hip flexors and abductors to achieve normalization of the hip and pelvis kinematics and consequently normalize hip loading. PMID:19560359

Lenaerts, G; Mulier, M; Spaepen, A; Van der Perre, G; Jonkers, I

2009-10-01

302

Stiffness of a 3-degree of freedom translational parallel kinematic machine  

NASA Astrophysics Data System (ADS)

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.

Shankar Ganesh, S.; Koteswara Rao, A. B.

2014-09-01

303

Stiffness of a 3-degree of freedom translational parallel kinematic machine  

NASA Astrophysics Data System (ADS)

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.

Shankar Ganesh, S.; Koteswara Rao, A. B.

2014-09-01

304

Kinematics and control algorithm development and simulation for a redundant two-arm robotic manipulator system  

NASA Technical Reports Server (NTRS)

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.

Hennessey, Michael P.; Huang, Paul C.; Bunnell, Charles T.

1989-01-01

305

INVERSE PROTEIN FOLDING, HIERARCHICAL OPTIMISATION  

E-print Network

INVERSE PROTEIN FOLDING, HIERARCHICAL OPTIMISATION AND TIE KNOTS Thomas M. A. Fink st. john Introduction 3 1.1 Inverse Protein Folding 3 1.2 Hierarchical Optimisation 5 1.3 Tie Knots 6 1.4 Schematic Organisation 6 1.5 Publications 9 2 Protein Folding, Inverse Protein Folding and Energy Landscapes 10 2

Halligan, Daniel

306

Inverse Problems in Systems Biology  

E-print Network

Inverse Problems in Systems Biology Heinz W.Engl Johann Radon Institute for Computational.W. Engl, C. Flamm, P. K¨ugler, J. Lu, S. M¨uller and P. Schuster, Inverse problems in systems biology, Inverse Problems 25 (2009) 1 #12;Systems biology is a relatively young biological discipline that claims

Fulmek, Markus

307

Modular Inverse Algorithms without Multiplications  

Microsoft Academic Search

the basic left-shift, right-shift and shifting Euclidean modular inverse algorithms are presented with new optimization tricks. These algorithms are based on the corresponding extended GCD algorithms, but only one multiplicator, the modular inverse is computed. On many computational platforms, for operand lengths used in cryptography, the fastest modular inverse algorithms need about twice the modular multiplication time, or even less.

Laszlo Hars

2004-01-01

308

Inverse avalanches on Abelian sandpiles  

SciTech Connect

A simple and computationally efficient way of finding inverse avalanches for Abelian sandpiles, called the inverse particle addition operator, is presented. In addition, the method is shown to be optimal in the sense that it requires the minimum amount of computation among methods of the same kind. The method is also conceptually succinct because avalanche and inverse avalanche are placed in the same footing.

Chau, H.F. (School of Natural Sciences, Institute for Advanced Study, Olden Lane, Princeton, New Jersey 08540 (United States) Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801-3080 (United States))

1994-11-01

309

Inverse problems in diffraction  

NASA Technical Reports Server (NTRS)

A two-dimensional problem of diffraction of a plane electromagnetic wave on a smooth 2 pi-periodic surface is considered. A numerical algorithm solving this problem is developed. An inverse problem of determination of the shape of 2 pi-periodic surface using the performance data of reverse scattering is considered. The inverse problem was solved by means of minimization of the residual functional with the help of the gradient descent method. The initial data were calculated with the help of the numerical method. On each step of the iterative method of minimization, the residual functional was calculated approximately with the help of the small slope method. The examples of the shape determination are considered.

Mikheev, Andrew G.; Shamaev, Aleksey S.

1991-01-01

310

Molecular Gas Kinematics in Barred Spiral Galaxies  

E-print Network

To quantify the effect that bar driven mass inflow can have on the evolution of a galaxy requires an understanding of the dynamics of the inflowing gas. In this paper we study the kinematics of the dense molecular gas in a set of seven barred spiral galaxies to determine which dynamical effects dominate. The kinematics are derived from observations of the CO J=(1-0) line made with the Berkeley-Illinois-Maryland Association (BIMA) millimeter array. We compare the observed kinematics to those predicted by ideal gas hydrodynamic and ballistic cloud-based models of gas flow in a barred potential. The hydrodynamic model is in good qualitative agreement with both the current observations of the dense gas and previous observations of the kinematics of the ionized gas. The observed kinematics indicate that the gas abruptly changes direction upon entering the dust lanes to flow directly down the dust lanes along the leading edge of the bar until the dust lanes approach the nuclear ring. Near the location where the dust lanes intersect the nuclear ring, we see two velocity components: a low velocity component, corresponding to gas on circular orbits, and a higher velocity component, which can be attributed to the fraction of gas flowing down the bar dust lane which sprays past the contact point toward the other half of the bar. The ballistic cloud-based model of the ISM is not consistent with the observed kinematics. The kinematics in the dust lanes require large velocity gradients which cannot be reproduced by an ISM composed of ballistic clouds with long mean-free-paths. Therefore, even the dense ISM responds to hydrodynamic forces.

Michael W. Regan; Kartik Sheth; Stuart N. Vogel

1999-08-10

311

Direct and Inverse Variation  

NSDL National Science Digital Library

"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.

Annenberg Media

2009-12-23

312

Inverse Square Law  

NSDL National Science Digital Library

In this math activity related to light, learners explore why a light, such as a candle or a streetlight, looks dimmer the farther away from it we get. The answer lies in the Inverse Square Law, which learners demonstrate using graph paper or perfboard. (Two methods are given for this activity.) Learners will discover that the intensity of light is described by the power distributed over an area.

The Exploratorium

2012-07-11

313

Interplanetary stream magnetism - Kinematic effects  

NASA Technical Reports Server (NTRS)

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.

Burlaga, L. F.; Barouch, E.

1976-01-01

314

The kinematics and force analysis of a new leg mechanism for multi-legged wall-climbing robot  

Microsoft Academic Search

This paper presents a new kind of leg mechanism with which the wall-climbing robot can easily perform the ground-to-wall transition\\u000a by itself. To get its walking envelope and limit position, the forward\\/inverse kinematics and the statics of the mechanism\\u000a are solved. All of these lay the foundation for ground-to-wall transition gait programing, mechanism parameter selection and\\u000a optimization.

Yi Luo; Jinwu Qian; Yaozong Shen; Zhenbang Gong

1998-01-01

315

Intersections, ideals, and inversion  

SciTech Connect

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.

Vasco, D.W.

1998-10-01

316

Kinematic reconstruction of the Caribbean region since the Early Jurassic  

NASA Astrophysics Data System (ADS)

The Caribbean region has a complex tectonic history that resulted from the interplay of the North and South American, the Caribbean, and (Paleo-)Pacific plates. Being largely surrounded by long-lived subduction zones and transform boundaries, reconstructing Caribbean plate motion into the global plate circuit cannot be done using marine magnetic anomalies. Here, we present a fully quantitative, kinematically consistent tectonic reconstruction, back to 200 Ma, using the Atlantic plate circuit as boundary condition. This reconstruction is made in GPlates freeware and all reconstruction files are made available. To restore Caribbean plate motion between the American continents, we use a reconstruction hierarchy based on strike-slip and thrust belt records, using regionally extensive geological phenomena such as the Great Arc of the Caribbean, the Caribbean Large Igneous Province (CLIP) and the Caribeana high-pressure belt as correlation markers. The resulting model restores the Caribbean plate back along the Cayman Trough and strike-slip faults in Guatemala, offshore Nicaragua, offshore Belize and along the Northern Andes towards its position of origin, west of the North and South American continents. Two plate kinematic scenarios for the origin of the Caribbean plate lithosphere are evaluated; an origin from Proto-Caribbean/Atlantic spreading, or from spreading within the Panthalassa domain: we conclude that the latter can provide a simpler explanation. Placing our reconstruction in the most recent mantle reference frames shows that the CLIP erupted 2-3000 km east of, and is probably not the result of the plume head stage of the Galápagos hotspot. Finally, our reconstruction suggests that all modern subduction zones surrounding the Caribbean plate probably formed by inversion of transform faults, two of these (along the southern Mexican and NW South American margins) strongly diachronously as a result of migrating trench-trench-transform triple junctions.

Boschman, L. M.; Van Hinsbergen, D. J.

2013-12-01

317

Kinematic evolution of the Northeast Japan convergent margin and implications for plate boundary dynamics  

NASA Astrophysics Data System (ADS)

Tectonic erosion along convergent plate boundaries, whereby removal of upper plate material along the subduction zone interface drives mass loss and subsidence of the outer forearc, has been invoked to explain the geologically recent evolution of nearly half the world's subduction margins. However, the mechanisms that initiate and sustain forearc subsidence are not well understood. We provide new analyses of the kinematic evolution of the northeast Japan margin, considered a type example of erosive margins, that demonstrate that vertical motions of the outer forearc are coincident with changes in upper plate kinematics and lower plate convergence rate. New constraints on the timing and kinematics of deformation along inner forearc faults indicate Plio-Quaternary inversion of Miocene extensional structures. The initiation of reverse slip along the inner forearc Futaba (5.6 to 3.9 Ma), Oritusme (5.9 to 4.8 Ma), and Noehij (Pliocene) faults are constrained by new U-Pb ages from tephras in growth strata. The initiation of an earlier phase of extension along the Oritusme and Futaba faults is identified from thick sequences of Miocene rift-related sediments in the hanging walls that are absent in the footwalls. Existing biostratigraphic and geochronolgic ages near the base of the syn-extensional sequences constrain the initiation of extension to 23.9-21.0 and ~20.8 Ma for the Futaba and Oritsume faults, and cross sections across these structures require nearly complete thrust inversion of Miocene extensional displacement. A regional synthesis of deformation demonstrates that the timing and kinematics of forearc deformation are contemporaneous with previously documented Miocene extension and Plio-Quaternary inversion in the backarc. Moreover, reconstructions of Pacific-Honshu convergence rates indicate that 1) the initiation of forearc subsidence and upper plate extension is coincident with a two to three fold increase in margin-perpendicular convergence, and 2) the onset of arc-normal shortening and increased frontal accretion occurred during a period of relatively constant convergence rate. The temporal correlation between deformation along upper plate faults, forearc subsidence, and lower plate convergence rates at the Northeast Japan margin suggests that the vertical motions of the forearc are likely governed by changes in lower plate kinematics. We hypothesize that an acceleration in plate convergence drives changes in slab geometry at shallow depths that allows for subsidence of the forearc, and suggest that a portion of the subsidence record previously interpreted as tectonic erosion instead reflects an upper plate response to plate boundary dynamics.

Regalla, C.; Fisher, D. M.; Furlong, K. P.; Kirby, E.

2012-12-01

318

Kinematic Models for Design Digital Library  

NSDL National Science Digital Library

The Kinematic Models for Design Digital Library (K-MODDL) is a collaborative effort of Cornell University librarians and faculty in Mechanical Engineering and Mathematics to provide open access, multimedia resources for learning and teaching about Kinematics. The website provides an overview of Kinematics, which is "the geometry of pure motion," along with a discussion of its history and contribution to a theory of machines. Funded by the National Science Digital Library of the National Science Foundation (NSF), K-MODDL is intended as "a pedagogical space" for use by teachers and researchers, and learners of all levels. The key feature of K-MODDL is the Reuleaux Collection of Mechanisms and Machines, which includes several interactive photographic animations and descriptions that illustrate kinematic mechanisms. Visitors may browse the models in the collection by category, or search by title words or by keyword (in English or German). Also available are educational tutorials, historical and contemporary texts related to the history and theory of machines and mechanisms, biographical information on important players in the history of machines and the field of kinematics, and finally, stereolithography files for â??printingâ? working physical replicas.

319

Kinematic and Spatial Substructure in NGC 2264  

NASA Astrophysics Data System (ADS)

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.

Tobin, John J.; Hartmann, Lee; F?rész, Gabor; Hsu, Wen-Hsin; Mateo, Mario

2015-04-01

320

Number-theoretic properties of hyperelliptic fields and the torsion problem in Jacobians of hyperelliptic curves over the rational number field  

NASA Astrophysics Data System (ADS)

In the past four years a theory has been developed for finding fundamental units in hyperelliptic fields, and on basis of this theory innovative and efficient algorithms for computing them have been constructed and implemented. A new local-global principle was discovered which gives a criterion for the existence of non-trivial units in hyperelliptic fields. The natural connection between the problem of computing fundamental units and the problem of torsion in Jacobian varieties of hyperelliptic curves over the rational number field has led to breakthrough results in the solution of this problem. The main results in the present survey were largely obtained using a symbiosis of deep theory, efficient algorithms, and supercomputing. Such a symbiosis will play an ever increasing role in the mathematics of the 21st century. Bibliography: 27 titles.

Platonov, V. P.

2014-02-01

321

Kinematics of the Ethiopian Rift and Absolute motion of Africa and Somalia Plates  

NASA Astrophysics Data System (ADS)

The Ethiopian Rift (ER), in the northern part of East African Rift System (EARS), forms a boundary zone accommodating differential motion between Africa and Somalia Plates. Its orientation was influenced by the inherited Pan-African collisional system and related lithospheric fabric. We present the kinematics of ER derived from compilation of geodetic velocities, focal mechanism inversions, structural data analysis, and construction of geological profiles. GPS velocity field shows a systematic eastward magnitude increase in NE direction in the central ER. In the same region, incremental extensional strain axes recorded by earthquake focal mechanism and fault slip inversion show ?N1000E orientation. This deviation between GPS velocity trajectories and orientation of incremental extensional strain is developed due to left lateral transtensional deformation. This interpretation is consistent with the en-échelon pattern of tensional and transtensional faults, the distribution of the volcanic centers, and the asymmetry of the rift itself. Small amount of vertical axis blocks rotation, sinistral strike slip faults and dyke intrusions in the rift accommodate the transtensional deformation. We analyzed the kinematics of ER relative to Deep and Shallow Hot Spot Reference Frames (HSRF). Comparison between the two reference frames shows different kinematics in ER and also Africa and Somalia plate motion both in magnitude and direction. Plate spreading direction in shallow HSRF (i.e. the source of the plumes locates in the asthenosphere) and the trend of ER deviate by about 27°. Shearing and extension across the plate boundary zone contribute both to the style of deformation and overall kinematics in the rift. We conclude that the observed long wavelength kinematics and tectonics are consequences of faster SW ward motion of Africa than Somalia in the shallow HSRF. This reference frame seems more consistent with the geophysical and geological constraints in the Rift. The faster SW motion of Africa with respect to Somalia plate is due to a possibly lower viscosity in the top asthenosphere (Low-Velocity Zone) beneath Africa. These findings have significant implications for the evolution of continental rifting in transtensional settings and provide evidence for the kinematics and tectonics of the Ethiopian rift in the context of the Africa-Somalia plate interaction in the mantle reference frame.

Muluneh, A. A.; Cuffaro, M.; Doglioni, C.

2013-12-01

322

Kinetic and kinematic differences between deadlifts and goodmornings  

PubMed Central

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

2013-01-01

323

Graph Theory Roots of Spatial Operators for Kinematics and Dynamics  

NASA Technical Reports Server (NTRS)

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.

Jain, Abhinandan

2011-01-01

324

Kinematics of the most efficient cilium.  

PubMed

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. PMID:22861901

Eloy, Christophe; Lauga, Eric

2012-07-20

325

Highly damped kinematic coupling for precision instruments  

DOEpatents

A highly damped kinematic coupling for precision instruments. The kinematic coupling provides support while causing essentially no influence to its nature shape, with such influences coming, for example, from manufacturing tolerances, temperature changes, or ground motion. The coupling uses three ball-cone constraints, each combined with a released flexural degree of freedom. This arrangement enables a gain of higher load capacity and stiffness, but can also significantly reduce the friction level in proportion to the ball radius divided by the distance between the ball and the hinge axis. The blade flexures reduces somewhat the stiffness of the coupling and provides an ideal location to apply constrained-layer damping which is accomplished by attaching a viscoelastic layer and a constraining layer on opposite sides of each of the blade flexures. The three identical ball-cone flexures provide a damped coupling mechanism to kinematically support the projection optics system of the extreme ultraviolet lithography (EUVL) system, or other load-sensitive apparatus.

Hale, Layton C. (Livermore, CA); Jensen, Steven A. (Livermore, CA)

2001-01-01

326

Parallel computation of geometry control in adaptive truss structures  

NASA Technical Reports Server (NTRS)

The fast computation of geometry control in adaptive truss structures involves two distinct parts: the efficient integration of the inverse kinematic differential equations that govern the geometry control and the fast computation of the Jacobian, which appears on the right-hand-side of the inverse kinematic equations. This paper present an efficient parallel implementation of the Jacobian computation on an MIMD machine. Large speedup from the parallel implementation is obtained, which reduces the Jacobian computation to an O(M-squared/n) procedure on an n-processor machine, where M is the number of members in the adaptive truss. The parallel algorithm given here is a good candidate for on-line geometry control of adaptive structures using attached processors.

Ramesh, A. V.; Utku, S.; Wada, B. K.

1992-01-01

327

Inverse torsional eigenvalue problems  

SciTech Connect

We undertake a numerical and theoretical investigation of the inverse problem for the reconstruction of the density rho and S-wave velocity ..beta.. of the Earth from its torsional oscillations. We assume a spherically symmetric, non-rotating Earth which consists of a perfect elastic, isotropic material and transform the differential equation governing the torsional oscillations to a Sturm-Liouville problem. We present a numerical method for determining rho and ..beta.. in the upper mantle when rho and ..beta.. are smooth functions of radius. The method, based on the Rayleigh-Ritz method, solves iteratively for the coefficients of a generalized Fourier series for the potential. We reconstruct several earth models to 2% accuracy. However, the method is sensitive to error in the data. This is not true of the inversion for the density alone and suggests that the simultaneous inversion for the density and velocity from free oscillation data may be unstable. The smoothness assumption is a serious limitation of our numerical method, since most earth models have a discontinuity at the crust and many have gradients with discontinuities in the upper mantle. We study the associated discontinuous Sturm-Liouville problem and prove that if the eigenfunctions have two discontinuities and if the potential is known in half the interval then the potential in the whole interval is uniquely determined from one spectrum. We apply this theorem to the discontinuous earth model to prove that given rho in the lower mantle and ..beta.. in the mantle and crust, then the torsional spectra of one angular order uniquely determine rho in the upper mantle. In addition, if ..beta.. is known only in the lower mantle, then two torsional spectra uniquely determine both rho and ..beta.. in the upper mantle.

Willis, C.

1983-06-01

328

An Inversion Model  

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.

329

Multiscale full waveform inversion  

NASA Astrophysics Data System (ADS)

We develop and apply a full waveform inversion method that incorporates seismic data on a wide range of spatio-temporal scales, thereby constraining the details of both crustal and upper-mantle structure. This is intended to further our understanding of crust-mantle interactions that shape the nature of plate tectonics, and to be a step towards improved tomographic models of strongly scale-dependent earth properties, such as attenuation and anisotropy. The inversion for detailed regional earth structure consistently embedded within a large-scale model requires locally refined numerical meshes that allow us to (1) model regional wave propagation at high frequencies, and (2) capture the inferred fine-scale heterogeneities. The smallest local grid spacing sets the upper bound of the largest possible time step used to iteratively advance the seismic wave field. This limitation leads to extreme computational costs in the presence of fine-scale structure, and it inhibits the construction of full waveform tomographic models that describe earth structure on multiple scales. To reduce computational requirements to a feasible level, we design a multigrid approach based on the decomposition of a multiscale earth model with widely varying grid spacings into a family of single-scale models where the grid spacing is approximately uniform. Each of the single-scale models contains a tractable number of grid points, which ensures computational efficiency. The multi-to-single-scale decomposition is the foundation of iterative, gradient-based optimization schemes that simultaneously and consistently invert data on all scales for one multi-scale model. We demonstrate the applicability of our method in a full waveform inversion for Eurasia, with a special focus on Anatolia where coverage is particularly dense. Continental-scale structure is constrained by complete seismic waveforms in the 30-200 s period range. In addition to the well-known structural elements of the Eurasian mantle, our model reveals a variety of subtle features, such as the Armorican Massif, the Rhine Graben and the Massif Central. Anatolia is covered by waveforms with 8-200 s period, meaning that the details of both crustal and mantle structure are resolved consistently. The final model contains numerous previously undiscovered structures, including the extension-related updoming of lower-crustal material beneath the Menderes Massif in western Anatolia. Furthermore, the final model for the Anatolian region confirms estimates of crustal depth from receiver function analysis, and it accurately explains cross-correlations of ambient seismic noise at 10 s period that have not been used in the tomographic inversion. This provides strong independent evidence that detailed 3-D structure is well resolved.

Fichtner, Andreas; Trampert, Jeannot; Cupillard, Paul; Saygin, Erdinc; Taymaz, Tuncay; Capdeville, Yann; Villaseñor, Antonio

2013-07-01

330

Morpho-kinematic Modeling of Nova Ejecta  

NASA Astrophysics Data System (ADS)

Morpho-kinematic modeling allows us to disentangle the morphology and kinematics of an object. The technique has been applied to a number of novae where resolved imaging, or lack of, and spectroscopic line profile fitting, show how we may retrieve important parameters of the system, such as the maximum expansion velocity, inclination angle and the morphology of the ejected shell. Furthermore, this technique may be used as a predictor for searches of eclipses which will then provide us further information on the system parameters, such as the orbital period and the white dwarf mass.

Ribeiro, V. A. R. M.

2014-12-01

331

Jet Kinematics of a Complete Blazar Sample  

NASA Astrophysics Data System (ADS)

We present kinematic results from the MOJAVE program, a large VLBA project to investigate the longterm structural and polarization evolution of jets associated with over 100 of the brightest radio-loud AGN in the northern sky. Since the sample is complete with respect to jet emission,we are able to deconvolve the effects of relativistic beaming to learn about the parent population of prominent blazars. We discuss the overall distribution of jet speeds and their dependence on other physical jet properties, and highlight several blazar jets that display unusual kinematics such as nozzle precession, accelerating features, and curved trajectories. The MOJAVE program is supported under National Science Foundation grant 0406923-AST.

Lister, Matthew L.; MOJAVE Collaboration

2007-12-01

332

Calibration of parallel kinematic devices using sequential determination of kinematic parameters  

SciTech Connect

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.

JOKIEL JR.,BERNHARD; BIEG,LOTHAR F.; ZIEGERT,JOHN C.

2000-04-06

333

A biomimetic approach to inverse kinematics for a redundant robot arm  

E-print Network

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, ...

Artemiadis, Panagiotis

334

The thick target inverse kinematics technique with a large acceptance silicon detector array  

NASA Astrophysics Data System (ADS)

An experimental technique for studying elastic scattering using a thick gas target is described, with a measurement of the ?(24Ne,?) reaction used as an example. Advantages such as ease, detector efficiency, and the possibility of measuring the cross section at 180° in the centre-of-mass are discussed. It is shown that a resolution of tens of keV is practical at zero degrees, and that the dominant contribution to the resolution for large angles is angular straggling of the beam in the entrance window. The use of helium gas as the target allows direct measurement of a-cluster states.

Walshe, J.; Freer, M.; Wheldon, C.; Achouri, L. N.; Ashwood, N. I.; Catford, W. N.; Celik, I. C.; Curtis, N.; Delaunay, F.; Fernández-Domínguez, B.; Grassi, L.; Kokalova, Tz; Marqués, M.; Orr, N. A.; Prepolec, L.; Scuderi, V.; Soi?, N.; Toki?, V.

2014-12-01

335

Transfer reactions in inverse kinematics: An experimental approach for fission investigations  

NASA Astrophysics Data System (ADS)

Inelastic and multinucleon transfer reactions between a 238U beam, accelerated at 6.14 MeV/u, and a 12C target were used for the production of neutron-rich, fissioning systems from U to Cm. A Si telescope, devoted to the detection of the targetlike nuclei, provided a characterization of the fissioning systems in atomic and mass numbers, as well as in excitation energy. Cross sections and angular and excitation-energy distributions were measured for the inelastic and transfer channels. Possible excitations of the targetlike nuclei were experimentally investigated for the first time, by means of ?-ray measurements. The decays from the first excited states of 12C, 11B, and 10Be were observed with probabilities of 0.12-0.14, while no evidence for the population of higher-lying states was found. Moreover, the fission probabilities of 238U, 239Np and 240,241,242Pu and 244Cm were determined as a function of the excitation energy.

Rodríguez-Tajes, C.; Farget, F.; Derkx, X.; Caamaño, M.; Delaune, O.; Schmidt, K.-H.; Clément, E.; Dijon, A.; Heinz, A.; Roger, T.; Audouin, L.; Benlliure, J.; Casarejos, E.; Cortina, D.; Doré, D.; Fernández-Domínguez, B.; Jacquot, B.; Jurado, B.; Navin, A.; Paradela, C.; Ramos, D.; Romain, P.; Salsac, M. D.; Schmitt, C.

2014-02-01

336

GESTURE SYNTHESIS FROM SIGN LANGUAGE NOTATION USING MPEG4 HUMANOID ANIMATION PARAMETERS AND INVERSE KINEMATICS  

Microsoft Academic Search

This paper presents a novel approach for generating VRML animation sequences from Sign Language notation, based on MPEG-4 Face and Body Animation. Sign Language notation, in the well-known SignWriting system, is provided as input and is initially converted to SWML (Sign Writing Markup Language), an XML-based format that has recently been developed for the storage, indexing and processing of Sign

Maria Papadogiorgaki; Nikos Grammalidis; L. Makris; Michael G. Strintzis

337

Inverse-kinematics proton scattering on $^{50}$Ca: Determining effective charges using complementary probes  

E-print Network

We have performed measurements of the $0_\\mathrm{g.s.}^+ \\rightarrow 2_1^+$ excitations in the neutron-rich isotopes $^{48,50}$Ca via inelastic proton scattering on a liquid hydrogen target, using the GRETINA $\\gamma$-ray tracking array. A comparison of the present results with those from previous measurements of the lifetimes of the $2_1^+$ states provides us the ratio of the neutron and proton matrix elements for the $0_\\mathrm{g.s.}^+ \\rightarrow 2_1^+$ transitions. These results allow the determination of the ratio of the proton and neutron effective charges to be used in shell model calculations of neutron-rich isotopes in the vicinity of $^{48}$Ca.

L. A. Riley; M. L. Agiorgousis; T. R. Baugher; D. Bazin; M. Bowry; P. D. Cottle; F. G. DeVone; A. Gade; M. T. Glowacki; K. W. Kemper; E. Lunderberg; D. M. McPherson; S. Noji; F. Recchia; B. V. Sadler; M. Scott; D. Weisshaar; R. G. T. Zegers

2014-07-20

338

Block model of western US kinematics from inversion of geodetic, fault slip, and earthquake data  

Microsoft Academic Search

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

R. McCaffrey

2003-01-01

339

A motion planner for a redundant mobile manipulator using the inverse kinematics  

E-print Network

This thesis is an effort to develop a powerful motion-planning algorithm for the mobile manipulator. The mobile manipulator is expected to work in partially defined or unstructured environments. In global/local approach, joint trajectories...

Gupta, Gautam Jagannath

2003-01-01

340

Transfer reaction studies in inverse kinematics with the magnetic spectrometer PRISMA  

NASA Astrophysics Data System (ADS)

The large solid angle magnetic spectrometers, in combination with large gamma arrays, allowed to perform reaction mechanism and nuclear structure studies in different regions of the nuclear chart, especially in the neutron-rich direction. By studying transfer of multiple pairs valuable information on nucleon-nucleon correlations can be derived, especially from measurements performed below the Coulomb barrier. There is growing interest in the study of the properties of the heavy binary partner, in the Pb and in the actinides regions, crucial also for astrophysics.

Corradi, L.

2015-01-01

341

A more general closed-form solution to the inverse kinematics of mechanical arms  

Microsoft Academic Search

This paper presents solutions to a number of different classes of robot manipulators obtained by locking the redundant joints in a redundant arm. This effort is part of the study of the flexibility offered by the introduction of additional degrees of freedom in mechanical arms. When the extra joints are randomly locked at arbitrary angles, the resultant will be non-redundant

A. Hemami

1987-01-01

342

Confounding T-wave inversion.  

PubMed

In the medical community, the nonspecific finding of T-wave inversion warrants further investigation. An electrocardiogram may be an essential component of a surgical risk evaluation. Patients who show a T-wave inversion on a preoperative electrocardiogram require further investigation to distinguish between pathological and benign T-wave inversion. Optimizing patients' safety during the perioperative experience is the ultimate clinical outcome. PMID:17322013

Bresnahan, Sandra; Eastwood, Jo-Ann

2007-03-01

343

Inverse filtering of room acoustics  

Microsoft Academic Search

A novel method is proposed for realizing exact inverse filtering of acoustic impulse responses in room. This method is based on the principle called the multiple-input\\/output inverse theorem (MINT). The inverse is constructed from multiple finite-impulse response (FIR) filters (transversal filters) by adding some extra acoustic signal-transmission channels produced by multiple loudspeakers or microphones. The coefficients of these FIR filters

M. Miyoshi; Y. Kaneda

1988-01-01

344

The Kinematics of Contact and Grasp  

Microsoft Academic Search

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

David J. Montana

1988-01-01

345

Kinematic comparisons of 1996 Olympic baseball pitchers  

Microsoft Academic Search

The aim of this study was to compare and evaluate the kinematics of baseball pitchers who participated in the 1996 XXVI Centennial Olympic Games. Two synchronized video cameras operating at 120 Hz were used to video 48 pitchers from Australia, Japan, the Netherlands, Cuba, Italy, Korea, Nicaragua and the USA. All pitchers were analysed while throwing the fastball pitch. Twenty-one

Rafael F. Escamilla; Glenn S. Fleisig; Nigel Zheng; Steven W. Barrentine; James R. Andrews

2001-01-01

346

Hickson 62.I. Kinematics of NGC4778  

E-print Network

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 group suggest that NGC4778 may be the product of a recent minor merger, more reliable with a small late-type galaxy.

M. Spavone; E. Iodice; G. Longo; M. Paolillo; S. Sodani

2006-06-30

347

Kinematic Measurements from YouTube Videos  

ERIC Educational Resources Information Center

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.…

Ruiz, Michael J.

2009-01-01

348

Kinematic-Wave Furrow Irrigation Model  

Microsoft Academic Search

A kinematic-wave model of furrow irrigation under both continu- ous and surged flow management was developed and verified. Numerical so- lution of the differential continuity equation is accomplished with a Eulerian first-order integration coupled with the assumption that flow rate and flow area are uniquely related by the Manning uniform flow equation. Field data from three Colorado sites, a Utah

Wynn R. Walker; Allan S. Humpherys

1983-01-01

349

Internal kinematics of H II galaxies  

NASA Astrophysics Data System (ADS)

H II galaxies are dwarf galaxies characterized by high stellar formation rate with spectrum dominated by strong emission lines, superimposed on a weak stellar continuum. The study of internal kinematics of these objects may be realized using the observed emission lines. Based on these lines we obtained monochromatic intensity, velocity dispersion and radial velocity maps. We have studied the internal kinematics of two H II galaxies: UM 461 and CTS 1020, observed with the Gemini South telescope using the GMOS instrument equipped with an IFU. We aim to investigate the origin of the line-broadening observed on emission lines from the use of kinematics diagnostic diagrams: I vs ?, I vs V, eV vs ?. The analysis of these diagrams was based on the Cometary Stirring Model that allows us to identify, for example, the presence of expanding shells and stellar winds. We found that radial velocity and velocity dispersion maps, for each galaxy, show a different kinematical pattern, although both are H II galaxies. CTS 1020 shows a velocity gradient consistent with a rotating disc with a velocity amplitude of ˜ 40 km s^{-1}. On the other hand UM 461 does not exhibit a typical pattern of a rotating system, despite of the observed velocity gradient in both emission nuclei.

Carvalho, M. S.; Plana, H.

2014-10-01

350

Kinematics of Stellar Populations in Poststarburst Galaxies  

NASA Astrophysics Data System (ADS)

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.

Hiner, Kyle D.; Canalizo, Gabriela

2015-01-01

351

Kinematic analysis of reaching in the cat  

Microsoft Academic Search

The present study examines the kinematic features of forelimb movements made by cats reaching for food in horizontal target wells located at different heights and distances. Wrist paths consisted of two relatively straight segments joined at a “via-point” in front of the aperture of the food well. In the initial lift phase, the paw was raised to the via-point in

J. H. Martin; S. E. Cooper; C. Ghez

1995-01-01

352

KINEMATIC DISTANCE ASSIGNMENTS WITH H I ABSORPTION  

SciTech Connect

Using H I absorption spectra from the International Galactic Plane Survey, a new method is implemented to resolve the kinematic distance ambiguity for 75 H II regions with known systemic velocities from radio recombination lines. A further 40 kinematic distance determinations are made for H II region candidates without known systemic velocities through an investigation of the presence of H I absorption around the terminal velocity. New kinematic distance determinations can be used to further constrain spiral arm parameters and the location and extent of other structures in the Milky Way disk. H I absorption toward continuum sources beyond the solar circle is also investigated. Follow-up studies of H I at higher resolution than the 1' to 2' of existing Galactic Plane Surveys will provide kinematic distances to many more H II regions on the far side of the Galactic center. On the basis of the velocity channel summation technique developed in this paper, a much larger sample of H II regions will be analyzed in a future paper to remove the near-far distance ambiguity.

Jones, Courtney; Dickey, John M. [School of Mathematics and Physics, Private Bag 37, University of Tasmania, Hobart 7000 (Australia)

2012-07-01

353

Gait kinematics for a serpentine robot  

Microsoft Academic Search

This paper considers the problem of serpentine, or snake-like, locomotion from the perspective of geometric mechanics. A particular model based on Hirose's active cord mechanism is analyzed. Using the kinematic constraints, we develop a connection, which describes the net motion of the machine as a function of variations in the mechanism's shape variables. We present simulation results demonstrating three types

Jim Ostrowski; Joel Burdick

1996-01-01

354

Deployable antenna kinematics using tensegrity structure design  

Microsoft Academic Search

With vast changes in spacecraft development over the last decade, a new, cheaper approach was needed for deployable kinematic systems such as parabolic antenna reflectors. Historically, these mesh-surface reflectors have resembled folded umbrellas, with incremental redesigns utilized to save packaging size. These systems are typically over-constrained designs, the assumption being that high reliability necessary for space operations requires this level

Byron Franklin Knight

2000-01-01

355

Constrained tri-sphere kinematic positioning system  

DOEpatents

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.

Viola, Robert J (Jackson, WY)

2010-12-14

356

The kinematic algebras from the scattering equations  

NASA Astrophysics Data System (ADS)

We study kinematic algebras associated to the recently proposed scattering equations, which arise in the description of the scattering of massless particles. In particular, we describe the role that these algebras play in the BCJ duality between colour and kinematics in gauge theory, and its relation to gravity. We find that the scattering equations are a consistency condition for a self-dual-type vertex which is associated to each solution of those equations. We also identify an extension of the anti-self-dual vertex, such that the two vertices are not conjugate in general. Both vertices correspond to the structure constants of Lie algebras. We give a prescription for the use of the generators of these Lie algebras in trivalent graphs that leads to a natural set of BCJ numerators. In particular, we write BCJ numerators for each contribution to the amplitude associated to a solution of the scattering equations. This leads to a decomposition of the determinant of a certain kinematic matrix, which appears naturally in the amplitudes, in terms of trivalent graphs. We also present the kinematic analogues of colour traces, according to these algebras, and the associated decomposition of that determinant.

Monteiro, Ricardo; O'Connell, Donal

2014-03-01

357

Kinematic synthesis of flight control systems  

E-print Network

and four bar position syntheses respectively. A case study of an elevator flight control system. The conventional primary flight control systems consist of ailerons, elevator, and rudder. They are used for movingKinematic synthesis of flight control systems for light aircrafts Yavuz Yaman Yunus Akman and Eres

Yaman, Yavuz

358

Compton Effect with Non-Relativistic Kinematics  

ERIC Educational Resources Information Center

In deducing the change of wavelength of x-rays scattered by atomic electrons, one normally makes use of relativistic kinematics for electrons. However, recoiling energies of the electrons are of the order of a few keV which is less than 0.2% of their rest energies. Hence the authors may ask whether relativistic formulae are really necessary. In…

Shivalingaswamy, T.; Kagali, B. A.

2011-01-01

359

Wavelet Sparse Approximate Inverse Preconditioners  

NASA Technical Reports Server (NTRS)

There is an increasing interest in using sparse approximate inverses as preconditioners for Krylov subspace iterative methods. Recent studies of Grote and Huckle and Chow and Saad also show that sparse approximate inverse preconditioner can be effective for a variety of matrices, e.g. Harwell-Boeing collections. Nonetheless a drawback is that it requires rapid decay of the inverse entries so that sparse approximate inverse is possible. However, for the class of matrices that, come from elliptic PDE problems, this assumption may not necessarily hold. Our main idea is to look for a basis, other than the standard one, such that a sparse representation of the inverse is feasible. A crucial observation is that the kind of matrices we are interested in typically have a piecewise smooth inverse. We exploit this fact, by applying wavelet techniques to construct a better sparse approximate inverse in the wavelet basis. We shall justify theoretically and numerically that our approach is effective for matrices with smooth inverse. We emphasize that in this paper we have only presented the idea of wavelet approximate inverses and demonstrated its potential but have not yet developed a highly refined and efficient algorithm.

Chan, Tony F.; Tang, W.-P.; Wan, W. L.

1996-01-01

360

Inverse problem for Bremsstrahlung radiation  

SciTech Connect

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.

Voss, K.E.; Fisch, N.J.

1991-10-01

361

Detailed stellar and gaseous kinematics of M31  

NASA Astrophysics Data System (ADS)

We have collected optical integral field spectroscopic data for M31 with the spectrograph VIRUS-W that result in kinematic maps of unprecedented detail. These reveal the presence of two kinematically distinct gas components.

Opitsch, Michael; Fabricius, Maximilian; Saglia, Roberto; Bender, Ralf; Williams, Michael

2015-02-01

362

A model of plate kinematics in Gondwana breakup  

NASA Astrophysics Data System (ADS)

An accurate model of relative plate motions in Gondwana breakup is based on visual fitting of seafloor isochrons and fracture zones (FZ) from the Riiser-Larsen Sea and Mozambique Basin. Used predictively, the model precisely locates kinematic markers in the West Somali Basin, which allows the conclusion that the spreading centres in the West Somali and Mozambique basins and the Riiser-Larsen Sea formed parts of the boundary between the same two plates. The locations of FZ and less well-defined isochrons from neighbouring regions are also consistent with their formation on other lengths of this same boundary and with its relocation from the West Somali Basin and northern Natal Valley to the West Enderby Basin and Lazarev Sea during chron M10n. Small independently moving plates thus played no role in the breakup of this core part of Gondwana. In an inversion procedure, the data from these areas yield more precise finite rotations that describe the history of the two plates' separation. Breakup is most simply interpreted to have occurred in coincidence with Karoo volcanism, and a reconstruction based on the rotations shows the Lebombo and Mateke-Sabi monoclines and the Mozambique and Astrid ridges as two sets of conjugate volcanic margins. Madagascar's pre-drift position can be used as a constraint to reassess the positions of India and Sri Lanka in the supercontinent.

Eagles, Graeme; König, Matthias

2008-05-01

363

Methodological analysis of finite helical axis behavior in cervical kinematics.  

PubMed

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

Cescon, Corrado; Cattrysse, Erik; Barbero, Marco

2014-10-01

364

The Maiden Voyage of a Kinematics Robot  

NASA Astrophysics Data System (ADS)

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).

Greenwolfe, Matthew L.

2015-04-01

365

Kinematic Optimization in Birds, Bats and Ornithopters  

NASA Astrophysics Data System (ADS)

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.

Reichert, Todd

366

Three-dimensional kinematics of hummingbird flight.  

PubMed

Hummingbirds are specialized for hovering flight, and substantial research has explored this behavior. Forward flight is also important to hummingbirds, but the manner in which they perform forward flight is not well documented. Previous research suggests that hummingbirds increase flight velocity by simultaneously tilting their body angle and stroke-plane angle of the wings, without varying wingbeat frequency and upstroke: downstroke span ratio. We hypothesized that other wing kinematics besides stroke-plane angle would vary in hummingbirds. To test this, we used synchronized high-speed (500 Hz) video cameras and measured the three-dimensional wing and body kinematics of rufous hummingbirds (Selasphorus rufus, 3 g, N=5) as they flew at velocities of 0-12 m s(-1) in a wind tunnel. Consistent with earlier research, the angles of the body and the stroke plane changed with velocity, and the effect of velocity on wingbeat frequency was not significant. However, hummingbirds significantly altered other wing kinematics including chord angle, angle of attack, anatomical stroke-plane angle relative to their body, percent of wingbeat in downstroke, wingbeat amplitude, angular velocity of the wing, wingspan at mid-downstroke, and span ratio of the wingtips and wrists. This variation in bird-centered kinematics led to significant effects of flight velocity on the angle of attack of the wing and the area and angles of the global stroke planes during downstroke and upstroke. We provide new evidence that the paths of the wingtips and wrists change gradually but consistently with velocity, as in other bird species that possess pointed wings. Although hummingbirds flex their wings slightly at the wrist during upstroke, their average wingtip-span ratio of 93% revealed that they have kinematically ;rigid' wings compared with other avian species. PMID:17575042

Tobalske, Bret W; Warrick, Douglas R; Clark, Christopher J; Powers, Donald R; Hedrick, Tyson L; Hyder, Gabriel A; Biewener, Andrew A

2007-07-01

367

Matrix-inversion method: Applications to Möbius inversion adn deconvolution  

Microsoft Academic Search

The purpose of this paper is threefold. The first is to show the matrix inversion method as a joint basis for the inversion of two important transforms: the Möbius and Laplace transforms. It is found that the Möbius transform is related to a multiplicative operator while the Laplace transform is related to an additive operator. The second is to show

Qian Xie; Nan-Xian Chen

1995-01-01

368

Foot Kinematics During a Bilateral Heel Rise Test in Participants With Stage II Posterior Tibial Tendon Dysfunction  

PubMed Central

STUDY DESIGN Experimental laboratory study using a cross-sectional design. OBJECTIVES To compare foot kinematics, using 3-dimensional tracking methods, during a bilateral heel rise between participants with posterior tibial tendon dysfunction (PTTD) and participants with a normal medial longitudinal arch (MLA). BACKGROUND The bilateral heel rise test is commonly used to assess patients with PTTD; however, information about foot kinematics during the test is lacking. METHODS Forty-five individuals volunteered to participate, including 30 patients diagnosed with unilateral stage II PTTD (mean ± SD age, 59.8 ± 11.1 years; body mass index, 29.9 ± 4.8 kg/m2) and 15 controls (mean ± SD age, 56.5 ± 7.7 years; body mass index, 30.6 ± 3.6 kg/m2). Foot kinematic data were collected during a bilateral heel rise task from the calcaneus (hindfoot), first metatarsal, and hallux, using an Optotrak motion analysis system and Motion Monitor software. A 2-way mixed-effects analysis of variance model, with normalized heel height as a covariate, was used to test for significant differences between the normal MLA and PTTD groups. RESULTS The patients in the PTTD group exhibited significantly greater ankle plantar flexion (mean difference between groups, 7.3°; 95% confidence interval [CI]: 5.1° to 9.5°), greater first metatarsal dorsiflexion (mean difference between groups, 9.0°; 95% CI: 3.7° to 14.4°), and less hallux dorsiflexion (mean difference, 6.7°; 95% CI: 1.7° to 11.8°) compared to controls. At peak heel rise, hindfoot inversion was similar (P = .130) between the PTTD and control groups. CONCLUSION Except for hindfoot eversion/inversion, the differences in foot kinematics in participants with stage II PTTD, when compared to the control group, mainly occur as an offset, not an alteration in shape, of the kinematic patterns. PMID:19648723

HOUCK, JEFF; NEVILLE, CHRISTOPHER; TOME, JOSHUA; FLEMISTER, ADOLPH

2010-01-01

369

Inverse magnetorheological fluids.  

PubMed

We report a new kind of field-responsive fluid consisting of suspensions of diamagnetic (DM) and ferromagnetic (FM) microparticles in ferrofluids. We designate them as inverse magnetorheological (IMR) fluids for analogy with inverse ferrofluids (IFFs). Observations on the particle self-assembly in IMR fluids upon magnetic field application showed that DM and FM microparticles were assembled into alternating chains oriented along the field direction. We explain such assembly on the basis of the dipolar interaction energy between particles. We also present results on the rheological properties of IMR fluids and, for comparison, those of IFFs and bidispersed magnetorheological (MR) fluids. Interestingly, we found that upon magnetic field application, the rheological properties of IMR fluids were enhanced with respect to bidispersed MR fluids with the same FM particle concentration, by an amount greater than the sum of the isolated contribution of DM particles. Furthermore, the field-induced yield stress was moderately increased when up to 30% of the total FM particle content was replaced with DM particles. Beyond this point, the dependence of the yield stress on the DM content was non-monotonic, as expected for FM concentrations decreasing to zero. We explain these synergistic results by two separate phenomena: the formation of exclusion areas for FM particles due to the perturbation of the magnetic field by DM particles and the dipole-dipole interaction between DM and FM particles, which enhances the field-induced structures. Based on the second phenomenon, we present a theoretical model for the yield stress that semi-quantitatively predicts the experimental results. PMID:25022363

Rodríguez-Arco, L; López-López, M T; Zubarev, A Y; Gdula, K; Durán, J D G

2014-09-01

370

Stress inversion assumptions review  

NASA Astrophysics Data System (ADS)

Wallace (1951) and Bott (1959) were the first to introduce the idea that the slip on each fault surface has the same direction and sense as the maximum shear stress resolved on that surface. This hypothesis are based on the assumptions that (i) faults are planar, (ii) blocks are rigid, (iii) neither stress perturbations nor block rotations along fault surfaces occur and (iv), the applied stress state is uniform. However, this simplified hypothesis is questionable since complex fault geometries, heterogeneous fault slip directions, evidences of stress perturbations in microstructures and block rotations along fault surfaces were reported in the literature. Earlier numerical geomechanical models confirmed that the striation lines (slip vectors) are not necessarily parallel to the maximum shear stress vector but is consistent with local stress perturbations. This leads us to ask as to what extent the Wallace and Bott simplifications are reliable as a basis hypothesis for stress inversion. In this presentation, a geomechanical multi-parametric study using 3D boundary element method (BEM), covering (i) fault geometries such as intersected faults or corrugated fault surfaces, (ii) the full range of Andersonian state of stress, (iii) fault friction, (iv) half space effect and (v), rock properties, is performed in order to understand the effect of each parameter on the angular misfit between geomechanical slip vectors and the resolved shear stresses. It is shown that significant angular misfits can be found under specific configurations and therefore we conclude that stress inversions based on the Wallace-Bott hypothesis might sometime give results that should be interpreted with care. Major observations are that (i) applying optimum tectonic stress conditions on complex fault geometries can increase the angular misfit, (ii) elastic material properties, combined to half-space effect, can enhance this effect, and (iii) an increase of the sliding friction leads to a reduction of this misfit.

Lejri, Mostfa; Maerten, Frantz; Maerten, Laurent; Joonnenkindt, Jean Pierre; Soliva, Roger

2014-05-01

371

Kinematics and space densities for the local cataclysmic variable population  

Microsoft Academic Search

I investigate the kinematics and space densities of the local cataclysmic variable (CV) population. CVs are close binary star systems composed of a white dwarf that accretes matter from a less compact companion star in Roche lobe overflow. Kinematics provide useful insight into the distances (and hence absolute magnitudes) of stellar populations. My kinematic sample consists of 359 independently measured

Christopher Scott Peters

2008-01-01

372

The Kinematic Car: Teaching Undergraduates Nonholonomic Mechanical System Basics  

Microsoft Academic Search

The project-based undergraduate J-term course Kinematics and Mechanism Design is described, both technically and from a pedagogy point of view. In this course students discovered the kinematic car, a classic example of a nonholonomic mechanical system that everyone can relate to; especially mechanical engineering students. Technical work entailed kinematic modeling using

Michael P. Hennessey

2003-01-01

373

Kinematic analysis of complex gear mechanisms Julie Penaud, Daniel Alazard  

E-print Network

Kinematic analysis of complex gear mechanisms Julie Penaud, Daniel Alazard Abstract This paper presents a general kinematic analysis method for complex gear mechanisms. This approach involves the null of free- dom car differential. Keywords: Kinematic analysis, gear train, graph the- ory, car differential

Mailhes, Corinne

374

Upper Limb Assessment in Tetraplegia: Clinical, Functional and Kinematic Correlations  

ERIC Educational Resources Information Center

The aim of this study was to correlate clinical and functional evaluations with kinematic variables of upper limp reach-to-grasp movement in patients with tetraplegia. Twenty chronic patients were selected to perform reach-to-grasp kinematic assessment using a target placed at a distance equal to the arm's length. Kinematic variables (hand peak…

Cacho, Enio Walker Azevedo; de Oliveira, Roberta; Ortolan, Rodrigo L.; Varoto, Renato; Cliquet, Alberto

2011-01-01

375

Analysis of kinematic, kinetic and electromyographic patterns during root canal preparation with rotary and manual instruments  

PubMed Central

Objective This study assessed the muscular activity during root canal preparation through kinematics, kinetics, and electromyography (EMG). Material and Methods The operators prepared one canal with RaCe rotary instruments and another with Flexo-files. The kinematics of the major joints was reconstructed using an optoelectronic system and electromyographic responses of the flexor carpi radialis, extensor carpi radialis, brachioradialis, biceps brachii, triceps brachii, middle deltoid, and upper trapezius were recorded. The joint torques of the shoulder, elbow and wrist were calculated using inverse dynamics. In the kinematic analysis, angular movements of the wrist and elbow were classified as low risk factors for work-related musculoskeletal disorders. With respect to the shoulder, the classification was medium-risk. Results There was no significant difference revealed by the kinetic reports. The EMG results showed that for the middle deltoid and upper trapezius the rotary instrumentation elicited higher values. The flexor carpi radialis and extensor carpi radialis, as well as the brachioradialis showed a higher value with the manual method. Conclusion The muscular recruitment for accomplishment of articular movements for root canal preparation with either the rotary or manual techniques is distinct. Nevertheless, the rotary instrument presented less difficulty in the generation of the joint torque in each articulation, thus, presenting a greater uniformity of joint torques. PMID:22437679

PASTERNAK-JÚNIOR, Braulio; de SOUSA NETO, Manoel Damião; DIONÍSIO, Valdeci Carlos; PÉCORA, Jesus Djalma; SILVA, Ricardo Gariba

2012-01-01

376

A deterministic model based on evidence for the associations between kinematic variables and sprint kayak performance.  

PubMed

The aim of this narrative review was to propose a deterministic model based on a review of previous research documenting the evidence for the associations between average kayak velocity and kinematic variables in sprint kayaking. Literature was reviewed after searching electronic databases using key words 'kayak,' 'biomechanics,' 'velocity,' 'kinematics,' and 'performance.' Our kinematic deterministic model for sprint kayaking performance shows that the average kayak velocity is determined by kayak stroke displacement and stroke time. Stroke time had the strongest correlation with 200-m race time (r = 0.86, p < 0.001), and stroke rate (inversely proportional to stroke time) was strongly correlated with average horizontal velocity over two consecutive strokes at race pace (r = -0.83, p < 0.05). Increased stroke rate via decreased absolute water phase time and increased relative water phase time were indicative of more elite performance. There was no significant relationship between stroke displacement and velocity; however, a large decrease in stroke displacement may be detrimental to performance. Individual characteristics may be responsible for a paddlers' ability to achieve and sustain a given stroke rate. Coaches should theoretically focus interventions on increasing stroke rate while maintaining stroke displacement; however this hypothesis should be confirmed with prospective studies. PMID:24245047

McDonnell, Lisa K; Hume, Patria A; Nolte, Volker

2013-09-01

377

3D kinematics using dual quaternions: theory and applications in neuroscience  

PubMed Central

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

Leclercq, Guillaume; Lefèvre, Philippe; Blohm, Gunnar

2013-01-01

378

Quantum imaging and inverse scattering.  

PubMed

We consider the inverse scattering problem that arises in two-photon quantum imaging with interferometric measurements. We show that the two-point correlation function of the field contains information about the scattering medium at a spatial frequency of twice the Rayleigh bandwidth. The linearized inverse problem, however, yields reconstructions with a resolution of ?/2, where ? is the wavelength of light. PMID:20967049

Schotland, John C

2010-10-15

379

Inverse problems in statistics Heidelberg, April 2007  

E-print Network

Inverse problems in statistics Heidelberg, April 2007 Laurent Cavalier 1) Inverse problems · Introduction · Linear inverse problems with random noise · Spectral Theorem · SVD and sequence space model) Conclusion 1 #12;1 Inverse problems 1.1 Introduction There exist many fields where inverse problems appear

Heermann, Dieter W.

380

Simple Rearrangement using Length-Weighted Inversions  

Microsoft Academic Search

Recent studies of genome rearrangement indicate a high proportion of short inversion events in genome evolution. This data motivates genome rearrangement models that reward short inversions and penalize long inver- sions. We study the optimization problem of sorting by inversions, where the cost of an inversion is proportional to its length. For the problem of sorting binary sequences by inversions,

Lina Dong; Saurabh Sethia; Pavel Sumazin

381

Two unconventional approaches to electromagnetic inversion Hierarchical Bayesian Inversion and Inverse Scattering Series  

NASA Astrophysics Data System (ADS)

Electromagnetic methods are effective complementary tools, when combined with seismic exploration, for the delineation of a hydrocarbon reservoir, because electromagnetic methods provide extra information about, for example, electric conductivity, which is an important property for the economic evaluation of reservoirs. In this study, we analyze unconventional approaches of electromagnetic inversion: hierarchical Bayesian inversion and inverse scattering series. We apply the hierarchical Bayesian inversion to the uncertainty analysis for the joint inversion and utilize rock-physics models to integrate these two disparate data sets. The study shows that the uncertainties in the seismic wave velocity and electric conductivity play a more significant role in the variation of posterior uncertainty than do the seismic and CSEM data noise. The numerical simulations also show that the uncertainty in porosity is most affected by the uncertainty in seismic wave velocity and that the uncertainty in water saturation is most influenced by the uncertainty in electric conductivity. The framework of the uncertainty analysis presented in this study can be utilized to effectively reduce the uncertainty of the porosity and water saturation derived from integration of seismic and CSEM data. We also study the feasibility of the inverse scattering series, which can effectively resolve the nonlinearity of an inverse problem, for the interpretation of electromagnetic data. The application of the inverse scattering series has been limited because the series converges when the reference model sufficiently close to the true model. This study quantifies convergence conditions of the inverse scattering series and suggests a different approach of the inverse series, the modified inverse scattering series, which guarantees the convergence of the series and facilitates the choice of a reference model.

Kwon, Myoung Jae

382

Cluster algebras in scattering amplitudes with special 2D kinematics  

NASA Astrophysics Data System (ADS)

We study the cluster algebra of the kinematic configuration space of an -particle scattering amplitude restricted to the special 2D kinematics. We found that the -point two-loop MHV remainder function in special 2D kinematics depends on a selection of the -coordinates that are part of a special structure of the cluster algebra related to snake triangulations of polygons. This structure forms a necklace of hypercube beads in the corresponding Stasheff polytope. Furthermore at , the cluster algebra and the selection of the -coordinates in special 2D kinematics replicates the cluster algebra and the selection of -coordinates of the two-loop MHV amplitude in 4D kinematics.

Torres, Marcus A. C.

2014-02-01

383

Goal Directed Model Inversion: A Study of Dynamic Behavior  

NASA Technical Reports Server (NTRS)

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.

Colombano, Silvano P.; Compton, Michael; Raghavan, Bharathi; Lum, Henry, Jr. (Technical Monitor)

1994-01-01

384

On kinematical constraints in Regge calculus  

E-print Network

In the (3+1)D Hamiltonian Regge calculus (one of the coordinates, $ t$, is continuous) conjugate variables are (defined on triangles of discrete 3D section $ t=const$) finite connections and antisymmetric area bivectors. The latter, however, are not independent, since triangles may have common edges. This circumstance can be taken into account with the help of the set of kinematical (that is, required to hold by definition of Regge manifold) bilinear constraints on bivectors. Some of these contain derivatives over $ t$, and taking them into account with the help of Lagrange multipliers would result in the new dynamical variables not having analogs in the continuum theory. It is shown that kinematical constraints with derivatives are consequences of eqs. of motion for Regge action supplemented with the rest of these constraints without derivatives and can be omitted; so the new dynamical variables do not appear.

V. Khatsymovsky

1993-11-04

385

Three-dimensional kinematic reconnection of plasmoids  

NASA Technical Reports Server (NTRS)

The kinematic reconnection model of Lau and Finn (1990) is applied in a theoretical investigation of three-dimensional plasmoid morphology, as seen in the solar corona and earth magnetotail. The derivation of the governing equations is outlined; long, short, and periodic plasmoid models are developed; and the evolution of the stable and unstable manifolds in these models is presented graphically. It is inferred that sheet currents and tangential discontinuities can form on surfaces topologically identical to those where Delta(phi) about equal to Delta(z) singularities occur in the kinematic reconnection model, and can be broadened in a similar way by nonideal effects. Two such surfaces exist in long plasmoids, and also in short plasmoids in the presence of finite resistivity; the intertwined surfaces characteristic of the periodic plasmoid form a fractal set but merge in the presence of finite resistivity, producing structures similar to those proposed by the sheet-current theory of Parker (1983).

Lau, Yun-Tung; Finn, John M.

1991-01-01

386

Kinematics of Gould's Belt: Model and Observations  

NASA Astrophysics Data System (ADS)

Using the available data for nearby stars we derive the velocity ellipsoid of dwarf O-B5.5 stars belonging to the Gould Belt (GB). The resulting vertex deviation for the whole sample is negative (l ~ -70^°) and this value is modified to l~ 20^° when the members of the Pleiades moving group are removed from the sample. This implies the existence of, at least, two different kinematic groups defining the GB system. We also model the evolution of a supershell in the solar neighborhood, and obtain a fit to the shape and kinematics of the gas in GB. Assuming that the expanding shell is also forming stars, we obtain the corresponding velocity fields for the shell and its newly formed stars. The average vertex deviation value resulting from these models for the new stars is l~ 20^°, and is consistent with the observed value when the Pleiades moving group members are excluded from the GB.

Alfaro, E. J.; Moreno, E.; Franco, J.

387

Identification of top quarks using kinematic variables  

SciTech Connect

We have used a kinematic technique to distinguish top quark pair production from background in {ital p{bar p}} collisions at {radical}{ital s}=1.8 TeV, applied to 67 pb{sup {minus}1} of data. We define a sample of {ital W}+{ge}3 jet events in which the jets are produced at large angles relative to the incident beams. In this sample, we find an excess of events with large jet transverse energies relative to expectations from background. The excess is consistent with top quark production; a large fraction of events in this kinematic region contains {ital b} jets. We interpret these results as evidence that most of the selected events are from {ital t{bar t}} decay.

Abe, F.; Akimoto, H.; Akopian, A.; Albrow, M.G.; Amendolia, S.R.; Amidei, D.; Antos, J.; Anway-Wiese, C.; Aota, S.; Apollinari, G.; Asakawa, T.; Ashmanskas, W.; Atac, M.; Auchincloss, P.; Azfar, F.; Azzi-Bacchetta, P.; Bacchetta, N.; Badgett, W.; Bagdasarov, S.; Bailey, M.W.; Bao, J.; de Barbaro, P.; Barbaro-Galtieri, A.; Barnes, V.E.; Barnett, B.A.; Bartalini, P.; Bauer, G.; Baumann, T.; Bedeschi, F.; Behrends, S.; Belforte, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Benlloch, J.; Bensinger, J.; Benton, D.; Beretvas, A.; Berge, J.P.; Bertolucci, S.; Bhatti, A.; Biery, K.; Binkley, M.; Bisello, D.; Blair, R.E.; Blocker, C.; Bodek, A.; Bokhari, W.; Bolognesi, V.; Bortoletto, D.; Boudreau, J.; Brandenburg, G.; Breccia, L.; Bromberg, C.; Buckley-Geer, E.; Budd, H.S.; Burkett, K.; Busetto, G.; Byon-Wagner, A.; Byrum, K.L.; Cammerata, J.; Campagnari, C.; Campbell, M.; Caner, A.; Carithers, W.; Carlsmith, D.; Castro, A.; Cauz, D.; Cen, Y.; Cervelli, F.; Chao, H.Y.; Chapman, J.; Cheng, M.; Chiarelli, G.; Chikamatsu, T.; Chiou, C.N.; Christofek, L.; Cihangir, S.; Clark, A.G.; Cobal, M.; Contreras, M.; Conway, J.; Cooper, J.; Cordelli, M.; Couyoumtzelis, C.; Crane, D.; Cronin-Hennessy, D.; Culbertson, R.; Cunningham, J.D.; Daniels, T.; DeJongh, F.; Delchamps, S.; Dell`Agnello, S.; Dell`Orso, M.; Demortier, L.; Denby, B.; Deninno, M.; Derwent, P.F.; Devlin, T.; Dickson, M.; Dittmann, J.R.; Donati, S.; Drucker, R.B.; Dunn, A.; Eddy, N.; Einsweiler, K.; Elias, J.E.; Ely, R.; Engels, E. Jr.; Errede, D.; Errede, S.; Fan, Q.; Fiori, I.; Flaugher, B.; Foster, G.W.; Franklin, M.; Frautschi, M.; Freeman, J.; Friedman, J.; Frisch, H.; Fuess, T.A.; Fukui, Y.; Funaki, S.; Gagliardi, G.; Galeotti, S.; Gallinaro, M.; Garcia-Sciveres, M.; Garfinkel, A.F.; Gay, C.; Geer, S.; Gerdes, D.W.; Giannetti, P.; Giokaris, N.; Giromini, P.; Gladney, L.; Glenzinski, D.; Gold, M.; Gonzalez, J.; Gordon, A.; Goshaw, A.T.; Goulianos, K.; Grassmann, H.; Groer, L.; Grosso-Pilcher, C.; CDF Collabora..

1995-09-01

388

Graph Models of Automobile Gears - Kinematics  

NASA Astrophysics Data System (ADS)

In the present paper, kinematical analysis of an automotive gear is described. Versatile graph based methods have been utilized for this purpose. An application of mixed, contour and bond graphs gives the same results. It allows the detection of possible mistakes as well as a deeper insight into the designed artifact. The graphs can also be used for further analyses which will be published in a separate document

Drewniak, J.; Kope?, J.; Zawi?lak, S.

2014-08-01

389

The Galactic Kinematics of Mira Variables  

E-print Network

The galactic kinematics of Mira variables derived from radial velocities, Hipparcos proper motions and an infrared period-luminosity relation are reviewed. Local Miras in the 145-200day period range show a large asymmetric drift and a high net outward motion in the Galaxy. Interpretations of this phenomenon are considered and (following Feast and Whitelock 2000) it is suggested that they are outlying members of the bulge-bar population and indicate that this bar extends beyond the solar circle.

Michael Feast

2002-07-09

390

Three-dimensional kinematics of wheelchair propulsion  

Microsoft Academic Search

A three-dimensional (3-D biomechanical model was used to determine upper extremity kinematics of 16 male subjects with low-level paraplegia while performing wheelchair propulsion (WCP). A six-camera VICON motion analysis system was used to acquire the coordinate data of ten anatomic markers. Joint axes for the wrist and elbow were defined along with the planes of motion for the upper arm

S. S. Rao; E. L. Bontrager; J. K. Gronley; C. J. Newsam; J. Perry

1996-01-01

391

Protogalactic Disk Models of Damped Lya Kinematics  

E-print Network

We present new observational results on the kinematics of the damped lya systems. Our full sample is now comprised of 31 low-ion profiles and exhibits similar characteristics to the sample from Paper I. The primary exception is that the new distribution of velocity widths includes values out to a maximum of nearly 300 km/s, approx 100 km/s greater than the previous maximum. These high velocity width systems will significantly leverage models introduced to explain the damped lya systems. Comparing the characteristics from low-redshift and high-redshift sub-samples, we find no evidence for significant evolution in the kinematic properties of protogalaxies from z = 2.0 - 3.3. The new observations give greater statistical significance to the main conclusions of our first paper. In particular, those models inconsistent with the damped lya observations in Paper I are ruled out at even higher levels of confidence. At the same time, the observations are consistent with a population of rapidly rotating, thick disks (the TRD model) at high redshift. Buoyed by the success of the TRD model, we investigate it more closely by considering more realistic disk properties. Our goal is to demonstrate the statistical power of the damped lya observations by investigating the robustness of the TRD model. In particular, we study the effects of warping, realistic rotation curves, and photoionization on the kinematics of disks in the TRD model. The principal results are: (1) disk warping has only minimal effect on the kinematic results, primarily influencing the effective disk thickness, (2) the TRD model is robust to more realistic rotation curves; (3) the effects of photoionization require thicker disks to give consistent velocity width distributions. [abridged

Jason X. Prochaska; Arthur M. Wolfe

1998-05-22

392

Kinematic analysis of prehension movements in children  

Microsoft Academic Search

The kinematics of the reach-to-grasp movement were analyzed in ten healthy children (age 6–7 years) under different experimental conditions: distance and size of the target objects, and visual feedback during the reach were varied in a within-subjects design. To assess age-related differences, the same experiments were performed in ten healthy adults. The experimental set-up was scaled according to body proportions

J. P Kuhtz-Buschbeck; H Stolze; A Boczek-Funcke; K Jöhnk; H Heinrichs; M Illert

1998-01-01

393

Efficient Kinematic Computations For 7-DOF Manipulators  

NASA Technical Reports Server (NTRS)

Efficient algorithms for forward kinematic mappings of seven-degree-of-freedom (7-DOF) robotic manipulator having revolute joints developed on basis of representation of redundant DOF in terms of parameter called "arm angle." Continuing effort to exploit redundancy in manipulator according to concept of basic and additional tasks. Concept also discussed in "Configuration-Control Scheme Copes With Singularities" (NPO-18556) and "Increasing the Dexterity of Redundant Robots" (NPO-17801).

Seraji, Homayoun; Long, Mark K.; Kreutz-Delgado, Kenneth

1994-01-01

394

Identification of top quarks using kinematic variables  

Microsoft Academic Search

We have used a kinematic technique to distinguish top quark pair production from background in pp¯ collisions at &surd;s=1.8 TeV, applied to 67 pb-1 of data. We define a sample of W+>=3 jet events in which the jets are produced at large angles relative to the incident beams. In this sample, we find an excess of events with large jet

F. Abe; H. Akimoto; A. Akopian; M. G. Albrow; S. R. Amendolia; D. Amidei; J. Antos; C. Anway-Wiese; S. Aota; G. Apollinari; T. Asakawa; W. Ashmanskas; M. Atac; P. Auchincloss; F. Azfar; P. Azzi-Bacchetta; N. Bacchetta; W. Badgett; S. Bagdasarov; M. W. Bailey; J. Bao; P. de Barbaro; A. Barbaro-Galtieri; V. E. Barnes; B. A. Barnett; P. Bartalini; G. Bauer; T. Baumann; F. Bedeschi; S. Behrends; S. Belforte; G. Bellettini; J. Bellinger; D. Benjamin; J. Benlloch; J. Bensinger; D. Benton; A. Beretvas; J. P. Berge; S. Bertolucci; A. Bhatti; K. Biery; M. Binkley; D. Bisello; R. E. Blair; C. Blocker; A. Bodek; W. Bokhari; V. Bolognesi; D. Bortoletto; J. Boudreau; G. Brandenburg; L. Breccia; C. Bromberg; E. Buckley-Geer; H. S. Budd; K. Burkett; G. Busetto; A. Byon-Wagner; K. L. Byrum; J. Cammerata; C. Campagnari; M. Campbell; A. Caner; W. Carithers; D. Carlsmith; A. Castro; D. Cauz; Y. Cen; F. Cervelli; H. Y. Chao; J. Chapman; M.-T. Cheng; G. Chiarelli; T. Chikamatsu; C. N. Chiou; L. Christofek; S. Cihangir; A. G. Clark; M. Cobal; M. Contreras; J. Conway; J. Cooper; M. Cordelli; C. Couyoumtzelis; D. Crane; D. Cronin-Hennessy; R. Culbertson; J. D. Cunningham; T. Daniels; F. Dejongh; S. Delchamps; L. Demortier; B. Denby; M. Deninno; P. F. Derwent; T. Devlin; M. Dickson; J. R. Dittmann; S. Donati; R. B. Drucker; A. Dunn; N. Eddy; K. Einsweiler; J. E. Elias; R. Ely; E. Jr. Engels; D. Errede; S. Errede; Q. Fan; I. Fiori; B. Flaugher; G. W. Foster; M. Franklin; M. Frautschi; J. Freeman; J. Friedman; H. Frisch; T. A. Fuess; Y. Fukui; S. Funaki; G. Gagliardi; S. Galeotti; M. Gallinaro; M. Garcia-Sciveres; A. F. Garfinkel; C. Gay; S. Geer; D. W. Gerdes; P. Giannetti; N. Giokaris; P. Giromini; L. Gladney; D. Glenzinski; M. Gold; J. Gonzalez; A. Gordon; A. T. Goshaw; K. Goulianos; H. Grassmann; L. Groer; C. Grosso-Pilcher; G. Guillian; R. S. Guo; C. Haber; S. R. Hahn; R. Handler; R. M. Hans; K. Hara; B. Harral; R. M. Harris; S. A. Hauger; J. Hauser; C. Hawk; E. Hayashi; J. Heinrich; M. Hohlmann; C. Holck; R. Hollebeek; L. Holloway; A. Ho; S. Hong; G. Houk; P. Hu; B. T. Huffman; R. Hughes; J. Huston; J. Huth; J. Hylen; H. Ikeda; M. Incagli; J. Incandela; J. Iwai; Y. Iwata; H. Jensen; U. Joshi; R. W. Kadel; E. Kajfasz; T. Kamon; T. Kaneko; K. Karr; H. Kasha; Y. Kato; L. Keeble; K. Kelley; R. D. Kennedy; R. Kephart; P. Kesten; D. Kestenbaum; R. M. Keup; H. Keutelian; F. Keyvan; B. J. Kim; D. H. Kim; H. S. Kim; S. B. Kim; S. H. Kim; Y. K. Kim; L. Kirsch; P. Koehn; K. Kondo; J. Konigsberg; S. Kopp; K. Kordas; W. Koska; E. Kovacs; W. Kowald; M. Krasberg; J. Kroll; M. Kruse; T. Kuwabara; S. E. Kuhlmann; E. Kuns; A. T. Laasanen; N. Labanca; S. Lammel; J. I. Lamoureux; T. Lecompte; S. Leone; J. D. Lewis; P. Limon; M. Lindgren; T. M. Liss; N. Lockyer; O. Long; C. Loomis; M. Loreti; J. Lu; D. Lucchesi; P. Lukens; S. Lusin; J. Lys; K. Maeshima; A. Maghakian; P. Maksimovic; M. Mangano; J. Mansour; M. Mariotti; J. P. Marriner; A. Martin; J. A. Matthews; R. Mattingly; P. McIntyre; P. Melese; A. Menzione; E. Meschi; S. Metzler; C. Miao; G. Michail; S. Mikamo; R. Miller; H. Minato; S. Miscetti; M. Mishina; H. Mitsushio; T. Miyamoto; S. Miyashita; Y. Morita; J. Mueller; A. Mukherjee; T. Muller; P. Murat; H. Nakada; I. Nakano; C. Nelson; D. Neuberger; C. Newman-Holmes; M. Ninomiya; L. Nodulman; S. Ogawa; S. H. Oh; K. E. Ohl; T. Ohmoto; T. Ohsugi; R. Oishi; M. Okabe; T. Okusawa; R. Oliver; J. Olsen; C. Pagliarone; R. Paoletti; V. Papadimitriou; S. P. Pappas; J. Patrick; G. Pauletta; M. Paulini; L. Pescara; M. D. Peters; T. J. Phillips; G. Piacentino; M. Pillai; K. T. Pitts; R. Plunkett; L. Pondrom; J. Proudfoot; F. Ptohos; G. Punzi; K. Ragan; A. Ribon; F. Rimondi; L. Ristori; W. J. Robertson; T. Rodrigo; J. Romano; L. Rosenson; R. Roser; W. K. Sakumoto; D. Saltzberg; L. Santi; H. Sato; V. Scarpine; P. Schlabach; E. E. Schmidt; M. P. Schmidt; G. F. Sciacca; A. Scribano; S. Segler; S. Seidel; Y. Seiya; G. Sganos; A. Sgolacchia; M. D. Shapiro; N. M. Shaw; Q. Shen; P. F. Shepard; M. Shimojima; M. Shochet; J. Siegrist; A. Sill; P. Sinervo; P. Singh; J. Skarha; K. Sliwa; D. A. Smith; F. D. Snider; T. Song; J. Spalding; P. Sphicas; L. Spiegel; A. Spies; L. Stanco; J. Steele; A. Stefanini; K. Strahl; J. Strait; D. Stuart; G. Sullivan; A. Soumarokov; K. Sumorok; J. Suzuki; T. Takada; T. Takahashi; T. Takano; K. Takikawa; N. Tamura; F. Tartarelli; W. Taylor; P. K. Teng; Y. Teramoto; S. Tether; D. Theriot; T. L. Thomas; R. Thun; M. Timko; P. Tipton; A. Titov; S. Tkaczyk; D. Toback; K. Tollefson; A. Tollestrup; J. Tonnison; J. F. de Troconiz; S. Truitt; J. Tseng; N. Turini; T. Uchida; N. Uemura; F. Ukegawa; G. Unal; S. C. van den Brink; S. Vejcik; G. Velev; R. Vidal; M. Vondracek; D. Vucinic; R. G. Wagner; R. L. Wagner; J. Wahl; R. C. Walker; C. Wang; G. Wang; J. Wang; M. J. Wang; Q. F. Wang; A. Warburton; G. Watts; T. Watts; R. Webb; C. Wei; C. Wendt

1995-01-01

395

New Kinematical Constraints on Cosmic Acceleration  

SciTech Connect

We present and employ a new kinematical approach to ''dark energy'' studies. We construct models in terms of the dimensionless second and third derivatives of the scale factor a(t) with respect to cosmic time t, namely the present-day value of the deceleration parameter q{sub 0} and the cosmic jerk parameter, j(t). An elegant feature of this parameterization is that all {Lambda}CDM models have j(t)=1 (constant), which facilitates simple tests for departures from the {Lambda}CDM paradigm. Applying our model to redshift-independent distance measurements, from type Ia supernovae and X-ray cluster gas mass fraction measurements, we obtain clear statistical evidence for a late time transition from a decelerating to an accelerating phase. For a flat model with constant jerk, j(t)=j, we measure q{sub 0}=-0.81 {+-} 0.14 and j=2.16 +0.81 -0.75, results that are consistent with {Lambda}CDM at about the 1{sigma} confidence level. In comparison to dynamical analyses, the kinematical approach uses a different model set and employs a minimum of prior information, being independent of any particular gravity theory. The results obtained with this new approach therefore provide important additional information and we argue that both kinematical and dynamical techniques should be employed in future dark energy studies, where possible.

Rapetti, David; Allen, Steve W.; Amin, Mustafa A.; Blandford, Roger; /-KIPAC, Menlo Park

2007-05-25

396

Milky Way Kinematics from RAVE Data  

NASA Astrophysics Data System (ADS)

We present a method to derive kinematic parameters for the Galactic thick and thin disks of the Milky Way (MW) based on the Radial Velocity Experiment (RAVE Steinmetz et al. 2006). We introduce selection criteria in order to clean the observed radial velocities from the Galactic large scale effects and to take into account the partial sky coverage of RAVE. The data are disentangled from a mixture of thin and thick disk stars as explained in a forthcoming paper (Pasetto et al. 2012) on the basis of pure kinematics arguments and supplied with photometric distances and proper motions. We deduce the components of the Solar motion relative to the Local Standard of Rest (LSR) in the radial and vertical directions as well as the components of the velocity dispersion tensors for the two MW component on the basis of pure kinematics arguments. The selected sample is a limited subsample from the RAVE catalogue roughly extending 500 pc above and below the Galactic plane. This sample tracks the velocity dispersion trend in radial direction to 1 kpc within and 500pc outside the Solar radius in the Galactic reference system.

Pasetto, S.; Grebel, E. K.; RAVE Co.

2012-08-01

397

Nonlinear Inverse Reinforcement Learning with Gaussian Processes  

E-print Network

Nonlinear Inverse Reinforcement Learning with Gaussian Processes Sergey Levine Stanford University inverse reinforcement learn- ing. The goal of inverse reinforcement learning is to learn the reward subop- timal stochastic demonstrations, while automatically balancing the simplicity of the learned

Washington at Seattle, University of

398

Model Fusion and Joint Inversion  

NASA Astrophysics Data System (ADS)

Inverse problems are inherently non-unique, and regularization is needed to obtain stable and reasonable solutions. The regularization adds information to the problem and determines which solution, out of the infinitely many, is obtained. In this paper, we review and discuss the case when a priori information exists in the form of either known structure or in the form of another inverse problem for a different property. The challenge is to include such information in the inversion process. To use existing known structure, we review the concept of model fusion, where we build a regularization functional that fuses the inverted model to a known one. The fusion is achieved by four different techniques. Joint inversion of two data sets is achieved by using iterative data fusion. The paper discusses four different methods for joint inversion. We discuss the use of correspondence maps or the petrophysics of the rocks, as well as structure. In particular, we suggest to further stabilize the well-known gradient cross product and suggest a new technique, Joint Total Variation, to solve the problem. The Joint Total Variation is a convex functional for joint inversion and, as such, has favorable optimization properties. We experiment with the techniques on the DC resistivity problem and the borehole tomography and show how model fusion and joint inversion can significantly improve over existing techniques.

Haber, Eldad; Holtzman Gazit, Michal

2013-09-01

399

Implementation of the Jacobian-free Newton-Krylov method for solving the for solving the first-order ice sheet momentum balance  

SciTech Connect

We have implemented the Jacobian-free Newton-Krylov (JFNK) method for solving the rst-order ice sheet momentum equation in order to improve the numerical performance of the Community Ice Sheet Model (CISM), the land ice component of the Community Earth System Model (CESM). Our JFNK implementation is based on signicant re-use of existing code. For example, our physics-based preconditioner uses the original Picard linear solver in CISM. For several test cases spanning a range of geometries and boundary conditions, our JFNK implementation is 1.84-3.62 times more efficient than the standard Picard solver in CISM. Importantly, this computational gain of JFNK over the Picard solver increases when rening the grid. Global convergence of the JFNK solver has been signicantly 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.

Salinger, Andy [Sandia National Laboratories (SNL); Evans, Katherine J [ORNL; Lemieux, Jean-Francois [New York University; Holland, David [New York University; Payne, Tony [University of Bristol, UK; Price, Stephen [Los Alamos National Laboratory (LANL); Knoll, Dana [Los Alamos National Laboratory (LANL)

2011-01-01

400

Moebius inversion formula and inverting lattice sums  

NASA Astrophysics Data System (ADS)

The Mobius inversion formula is an interesting theorem from number theory that has application to a number inverse problems, particularly lattice problems. Specific inverse problems, however, often require related Mobius inversion formulae that can be derived from the fundamental formula. Derivation of such formulae is not easy for the non- specialist, however. Examples of the kinds of inversion formulae that can be derived and their application to inverse lattice problems are described.

Millane, Rick P.

2000-11-01

401

Statistical principles of inversion theory  

NASA Technical Reports Server (NTRS)

Statistical methods are used to deal with the inverse problem of radiative transfer. All the available information about an unknown profile can be expressed in the form of values of functions of that profile and error estimates of these values. Estimation theory shows how these values are combined to give an estimate of the unknown profile and its error covariance. Many inversion methods are expressed in this form, although the error estimate is not usually carried out. Practical applications are described, both for inversion of individual profiles, and the global analysis of satellite data.

Rodgers, C. D.

1977-01-01

402

Source Inversion Validation: Quantifying Uncertainties in Earthquake Source Inversions  

NASA Astrophysics Data System (ADS)

Earthquake source inversions image the spatio-temporal rupture evolution on one or more fault planes using seismic and/or geodetic data. Source inversion methods thus represent an important research tool in seismology to unravel the complexity of earthquake ruptures. Subsequently, source-inversion results are used to study earthquake mechanics, to develop spontaneous dynamic rupture models, to build models for generating rupture realizations for ground-motion simulations, and to perform Coulomb-stress modeling. In all these applications, the underlying finite-source rupture models are treated as “data” (input information), but the uncertainties in these data (i.e. source models obtained from solving an inherently ill-posed inverse problem) are hardly known, and almost always neglected. The Source Inversion Validation (SIV) project attempts to better understand the intra-event variability of earthquake rupture models. We plan to build a long-standing and rigorous testing platform to examine the current state-of-the-art in earthquake source inversion that also facilitates to develop robust approaches to quantify rupture-model uncertainties. Our contribution reviews the current status of the SIV project, recent forward-modeling tests for point and extended sources in layered media, and discusses the strategy of the SIV-project for the coming years.

Mai, P. M.; Page, M. T.; Schorlemmer, D.

2010-12-01

403

Kalman filtering, smoothing and recursive robot arm forward and inverse dynamics  

NASA Technical Reports Server (NTRS)

The inverse and forward dynamics problems for multi-link serial manipulators are solved by using recursive techniques from linear filtering and smoothing theory. The pivotal step is to cast the system dynamics and kinematics as a two-point boundary-value problem. Solution of this problem leads to filtering and smoothing techniques identical to the equations of Kalman filtering and Bryson-Frazier fixed time-interval smoothing. The solutions prescribe an inward filtering recursion to compute a sequence of constraint moments and forces followed by an outward recursion to determine a corresponding sequence of angular and linear accelerations. In addition to providing techniques to compute joint accelerations from applied joint moments (and vice versa), the report provides an approach to evaluate recursively the composite multi-link system inertia matrix and its inverse. The report lays the foundation for the potential use of filtering and smoothing techniques in robot inverse and forward dynamics and in robot control design.

Rodriguez, G.

1986-01-01

404

Application of a digital signal processor in compliant Cartesian control of an industrial manipulator  

Microsoft Academic Search

This paper presents an example of compliant manipulator control implemented on a DSP chip. Drake and Hsia (1993) discussed the algorithms for computing the manipulator forward and inverse kinematics, Jacobian, J(?), J-1, J˙?˙, and Newton-Euler inverse dynamics. These algorithms were unified under a common coordinate system and optimized. Here, these tools have been augmented by a six D.O.F Cartesian trajectory

T. A. Lasky; T. C. Hsia

1994-01-01

405

Temperature Inversions Have Cold Bottoms.  

ERIC Educational Resources Information Center

Uses discussion and illustrations of several demonstrations on air temperature differences and atmospheric stability to explain the phenomena of temperature inversions. Relates this to the smog in Los Angeles and discusses the implications. (DC)

Bohren, Craig F.; Brown, Gail M.

1982-01-01

406

Inversion layer MOS solar cells  

NASA Technical Reports Server (NTRS)

Inversion layer (IL) Metal Oxide Semiconductor (MOS) solar cells were fabricated. The fabrication technique and problems are discussed. A plan for modeling IL cells is presented. Future work in this area is addressed.

Ho, Fat Duen

1986-01-01

407

Action understanding as inverse planning  

E-print Network

Humans are adept at inferring the mental states underlying other agents’ actions, such as goals, beliefs, desires, emotions and other thoughts. We propose a computational framework based on Bayesian inverse planning for ...

Baker, Christopher Lawrence

408

Geophysical Inversion Tutorials and Workflows  

NSDL National Science Digital Library

Geophysical inversion is deriving the structure of the Earth's subsurface from data collected at the surface, using a formal 'inversion' algorithm that creates a subsurface model structure directly from the surface observations. This portal provides links to introductory articles, online tutorials, and workflows for use in geoscience tasks such as mineral exploration, geotechnical or environmental engineering. The tutorials introduce basic concepts, explain how inversion works, and include applets for modeling linear inversion and magnetic dipoles. The workflows section includes procedures for inverting DC resistivity survey data to obtain 2-dimensional models of subsurface electrical conductivity and for inverting magnetic (or gravity) survey data to obtain 3-dimensional models of subsurface magnetic susceptibility (or density) distributions. There are also links to brief summaries on survey methods, geophysical models, and a seven-step framework for carrying out geophysical surveys.

409

Bayesian Nonparametric Inverse Reinforcement Learning  

E-print Network

Inverse reinforcement learning (IRL) is the task of learning the reward function of a Markov Decision Process (MDP) given the transition function and a set of observed demonstrations in the form of state-action pairs. ...

How, Jonathan P.

410

Uterine Inversion; A case report  

PubMed Central

The puerperal uterine inversion is a rare and severe complication occurring in the third stage of labour. The mechanisms are not completely known. However, extrinsic factors such as oxytocic arrests after a prolonged labour, umbilical cord traction or abdominal expression are pointed. Other intrinsic factors such as primiparity, uterine hypotonia, various placental localizations, fundic myoma or short umbilical cord were also reported. The diagnosis of the uterine inversion is mainly supported by clinical symptoms. It is based on three elements: haemorrhage, shock and a strong pelvic pain. The immediate treatment of the uterine inversion is required. It is based on a medical reanimation associated with firstly a manual reduction then surgical treatment using various techniques. We report an observation of a 25 years old grand multiparous patient with a subacute uterine inversion after delivery at home. PMID:21516244

Bouchikhi, C; Saadi, H; Fakhir, B; Chaara, H; Bouguern, H; Banani, A; Melhouf, MA

2008-01-01

411

Donor states in inverse opals  

SciTech Connect

We calculate the binding energy of an electron bound to a donor in a semiconductor inverse opal. Inverse opals have two kinds of cavities, which we call octahedral and tetrahedral, according to their group symmetry. We put the donor in the center of each of these two cavities and obtain the binding energy. The binding energies become very large when the inverse opal is made from templates with small spheres. For spheres less than 50?nm in diameter, the donor binding can increase to several times its unconfined value. Then electrons become tightly bound to the donor and are unlikely to be thermally activated to the semiconductor conduction band. This conclusion suggests that inverse opals will be poor conductors.

Mahan, G. D. [Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

2014-09-21

412

Kinematic Rupture Process Of Karakocan-Elazig Earthquake, Eastern Turkey  

NASA Astrophysics Data System (ADS)

An earthquake (Mw=5.9) hit Elazig in the eastern part of Turkey on March 8, 2010 at 02:32 (GMT). It is located midway between the provincial capital of Elaz?? and Bingöl with coordinates reported as 38o48.42N and 40o5.99E by Bogazici University Kandilli Observatory and Earthquake Research Institute (KOERI). Source characterization and slip history were estimated the main and four moderate size earthquake almost at the same location. The earthquake occurred at one of the tectonically very active East Anatolian Fault zone starts at the Karl?ova triple junction, where it meets the North Anatolian fault to the NE. Multi time-window linear waveform inversion technique (MTWIT) was applied to strong ground motion (SGM) data. Theoretical Green's functions between subfaults and stations were calculated by a Discrete Wave Number Method (DWNM) using 1-D velocity structure. Inversion technique used in this study yields a non unique solution. Therefore various rupture models have been tried until both observed and synthetic data were matched. Results show simple patterns in slip distributions. Maximum slip is 0.78 and seismic moment is 1.435E+25 dyne.cm from the kinematic rupture process of the strike slip faulting. In this study, we searched a stable 1-D crustal velocity model with low RMS misfit to construct the theoretical Green's function between each sub-fault and each station among the 4 different models. These are Preliminary Reference Earth Model (PREM; Dziewonski and Anderson, 1981), International Association of Seismology and the Physics of the Earth's Interior (IASP91) (Kennett and Engdahl, 1991), Kandilli Observatory and Earthquake Research Institute (KOERI) earthquake location model, explosion model (Gurbuz, 2004). We have collected previous studies Rebollar et al., (2001), Ichinose et al., (1997), Abdel-Fattah (2002), Somerville et al., (1999), Wells and Coppersmith (1994) on source information of moderate size earthquakes occurred worldwide and compared with our results. Results were compared with those of similar size earthquakes around the world and a new empirical relationship was proposed between seismic moment and rupture area. We expect our findings provide usefull information to resolving rupture mechanisms and triggering of the events in Eastern Anatoion Region. Key Words: Rupture Process, Elazig Earthquake, Eastern Turkey

Bekler, F. N.; Ozel, N. M.; Tanircan, G. B.

2012-04-01

413

EDITORIAL: Inverse Problems in Engineering  

NASA Astrophysics Data System (ADS)

Presented here are 11 noteworthy papers selected from the Fifth International Conference on Inverse Problems in Engineering: Theory and Practice held in Cambridge, UK during 11-15 July 2005. The papers have been peer-reviewed to the usual high standards of this journal and the contributions of reviewers are much appreciated. The conference featured a good balance of the fundamental mathematical concepts of inverse problems with a diverse range of important and interesting applications, which are represented here by the selected papers. Aspects of finite-element modelling and the performance of inverse algorithms are investigated by Autrique et al and Leduc et al. Statistical aspects are considered by Emery et al and Watzenig et al with regard to Bayesian parameter estimation and inversion using particle filters. Electrostatic applications are demonstrated by van Berkel and Lionheart and also Nakatani et al. Contributions to the applications of electrical techniques and specifically electrical tomographies are provided by Wakatsuki and Kagawa, Kim et al and Kortschak et al. Aspects of inversion in optical tomography are investigated by Wright et al and Douiri et al. The authors are representative of the worldwide interest in inverse problems relating to engineering applications and their efforts in producing these excellent papers will be appreciated by many readers of this journal.

West, Robert M.; Lesnic, Daniel

2007-01-01

414

Trans-dimensional finite-fault inversion  

NASA Astrophysics Data System (ADS)

This paper develops a probabilistic Bayesian approach to the problem of inferring the spatiotemporal evolution of earthquake rupture on a fault surface from seismic data with rigorous uncertainty estimation. To date, uncertainties of rupture parameters are poorly understood, and the effect of choices such as fault discretization on uncertainties has not been studied. We show that model choice is fundamentally linked to uncertainty estimation and can have profound effects on results. The approach developed here is based on a trans-dimensional self-parametrization of the fault, avoids regularization constraints and provides rigorous uncertainty estimation that accounts for model-selection ambiguity associated with the fault discretization. In particular, the fault is parametrized using self-adapting irregular grids which intrinsically match the local resolving power of the data and provide parsimonious solutions requiring few parameters to capture complex rupture characteristics. Rupture causality is ensured by parametrizing rupture-onset time by a rupture-velocity field and obtaining first rupture times from the eikonal equation. The Bayesian sampling of the parameter space is implemented on a computer cluster with a highly efficient parallel tempering algorithm. The inversion is applied to simulated and observed W-phase waveforms from the 2010 Maule (Chile) earthquake. Simulation results show that our approach avoids both over- and underparametrization to ensure unbiased inversion results with uncertainty estimates that are consistent with data information. The simulation results also show the ability of W-phase data to resolve the spatial variability of slip magnitude and rake angles. In addition, sensitivity to spatially dependent rupture velocities exists for kinematic slip models. Application to the observed data indicates that residual errors are highly correlated and likely dominated by theory error, necessitating the iterative estimation of a non-stationary data covariance matrix. The moment magnitude for the Maule earthquake is estimated to be ˜8.9, with slip concentrated in two zones updip of and north and south of the hypocentre, respectively. While this aspect of the slip distribution is similar to previous studies, we show that the slip maximum in the southern zone is poorly resolved compared to the northern zone. Both slip maxima are higher than reported in previous studies, which we speculate may be due to the lack of bias caused by the regularization used in other studies.

Dettmer, Jan; Benavente, Roberto; Cummins, Phil R.; Sambridge, Malcolm

2014-11-01

415

Inverse Problems in Hyperspectral Imaging  

NASA Astrophysics Data System (ADS)

In hyperpsectral imaging, multiple images of the same scene are obtained over a contiguous range of wavelengths in the electromagnetic spectrum. Hyperspectral images represent observations of a scene at many different wavelengths and most importantly associate to each pixel in the imaged scene a full spectral vector or spectral signature. However, due to the presence of spectral mixtures (at different scales) in the scene and/or low spatial resolution of the hyperspectral sensor, the acquired spectral vectors of each pixel are actually a mixture of the spectra of the various materials present in the spatial coverage area of the corresponding pixel, and they also contain additional degradations caused by atmospheric blurring.We present a numerical approach for deblurring and sparse unmixing of space objects taken by ground based telescopes. A major challenge for deblurring hyperspectral images is that of estimating the overall blurring operator, taking into account the fact that the blurring operator point spread function (PSF) can be wavelength dependent and depend on the imaging system as well as the effects of atmospheric turbulence. We formulate the PSF estimation as a nonlinear least squares problem, which is solved using a variable projection Gauss-Newton method. Our analysis shows that the Jacobian can be potentially very ill-conditioned. To deal with this ill-conditioning, we use a combination of subset selection and regularization. We then incorporate the PSF estimation scheme with a preconditioned alternating direction method of multipliers to solve the deblurring and sparse unmixing problem. Experimental results illustrate the effectiveness of the resulting numerical schemes.

Berisha, Sebastian

416

A Kinematical Approach to Dark Energy Studies  

SciTech Connect

We present and employ a new kinematical approach to cosmological ''dark energy'' studies. We construct models in terms of the dimensionless second and third derivatives of the scale factor a(t) with respect to cosmic time t, namely the present-day value of the deceleration parameter q{sub 0} and the cosmic jerk parameter, j(t). An elegant feature of this parameterization is that all {Lambda}CDM models have j(t) = 1 (constant), which facilitates simple tests for departures from the {Lambda}CDM paradigm. Applying our model to the three best available sets of redshift-independent distance measurements, from type Ia supernovae and X-ray cluster gas mass fraction measurements, we obtain clear statistical evidence for a late time transition from a decelerating to an accelerating phase. For a flat model with constant jerk, j(t) = j, we measure q{sub 0} = -0.81 {+-} 0.14 and j = 2.16{sub -0.75}{sup +0.81}, results that are consistent with {Lambda}CDM at about the 1{sigma} confidence level. A standard ''dynamical'' analysis of the same data, employing the Friedmann equations and modeling the dark energy as a fluid with an equation of state parameter, w (constant), gives {Omega}{sub m} = 0.306{sub -0.040}{sup +0.042} and w = -1.15{sub -0.18}{sup +0.14}, also consistent with {Lambda}CDM at about the 1{sigma} level. In comparison to dynamical analyses, the kinematical approach uses a different model set and employs a minimum of prior information, being independent of any particular gravity theory. The results obtained with this new approach therefore provide important additional information and we argue that both kinematical and dynamical techniques should be employed in future dark energy studies, where possible. Our results provide further interesting support for the concordance {Lambda}CDM paradigm.

Rapetti, David; Allen, Steven W.; Amin, Mustafa A.; Blandford, Roger D.; /KIPAC, Menlo Park

2006-06-06

417

The Kinematics of Dwarf Carbon Stars  

NASA Astrophysics Data System (ADS)

The presence of molecular carbon absorption bands in the spectra of main sequence dwarfs is remarkable, as these stars have not yet evolved through the helium-burning and dredge-up phases that deposit carbon in a stellar photosphere. Dwarf carbon stars are thus generally considered members of post-mass transfer binaries, with the main sequence star polluted by an evolved, often now invisible, companion. For decades only a handful were known. Now it is recognized that carbon dwarfs likely outnumber the better-understood giant carbon stars. Green (2013) has identified more than 700 carbon dwarfs from the Sloan Digital Sky Survey (SDSS). This large sample- distributed nearly evenly throughout the SDSS footprint- makes a study of stellar kinematics possible for dwarf carbon stars as a class.We examine the proper motions and radial velocities of ~700 carbon dwarfs and compare to a sample of 2×104 non-carbon main sequence stars from the SDSS archive. The spectra of carbon dwarfs and giants can appear indistinguishable, and so the relatively faint carbon dwarfs are recognized only if they have a sufficiently large proper motion to exclude the possibility of their being distant giants. We build our non-carbon control sample by the same proper motion criteria and additionally require that the control stars match the carbon dwarf selection with respect to properties such as photometric colors. In order to examine the kinematics of a sample spread across a large portion of sky, we compare each carbon dwarf with a group of control stars separated from it by less than three degrees. Preliminary results suggest that carbon dwarfs' kinematics are similar to the distributions of their neighboring control stars. We will present the results of detailed tests, including an investigation of several carbon dwarfs with atypical radial velocities.

Plant, Kathryn A.; Margon, Bruce H.; Guhathakurta, Puragra; Rockosi, Constance M.

2015-01-01

418

Influence of muscle contraction on whiplash kinematics.  

PubMed

It is unclear whether reflexive muscle contraction in unaware occupants can alter spinal kinematics to mitigate injury in the unaware occupant subjected to whiplash loading. Whiplash injury likely occurs during the non-physiologic S-curvature phase of spinal kinematics, present during the first 100 msec after the initiation of T1 acceleration. Experimental investigations using human volunteers have reported 45 to 60 msec delays prior to electrical activity of the sternocleidomastoid. The effects of reflexive contraction of the neck muscles were investigated using a validated head-neck computational model consisting of head, cervical spine, and first thoracic vertebra. Intervertebral discs. spinal ligaments, and facet joints were modeled using discrete elements. Passive and active musculature were incorporated using the Hill-type muscle model. The computational model was subjected to 2.6 m/sec rear impact velocity, applied to T1. Reflexive muscle contraction in the unaware occupant model was incorporated using a 54-msec muscle delay, 13-msec electromechanical delay, and an 81-msec muscle rise time. Results of the unaware occupant model were compared to the model exercised without muscle contraction. Reflexive muscle contraction altered segmental angulations by less than 10% and facet joint capsular ligament distractions by less than 16% during the time of maximum S-curvature. At the C5-C6 and C6-C7 levels, muscle contraction increased capsular ligament distractions. Due to the nominal affect of reflexive muscle contraction on segmental angulations and facet joint capsular ligament distractions during S-curvature, it is unlikely that this contraction can alter the cervical kinematics responsible for whiplash injury. PMID:15133930

Stemper, Brian D; Yoganandan, Narayan; Pintar, Frank A

2004-01-01

419

Kinematic Bias in Cosmological Distance Measurement  

E-print Network

Recent calculations using non-linear relativistic cosmological perturbation theory show biases in the mean luminosity distance and distance modulus at low redshift. We show that these effects may be understood very simply as a non-relativistic, and purely kinematic, Malmquist-like bias, and we describe how the effect changes if one averages over sources that are limited by apparent magnitude. This effect is essentially identical to the distance bias from small-scale random velocities that has previously been considered by astronomers, though we find that the standard formula overestimates the homogeneous bias by a factor 2.

Kaiser, Nick

2015-01-01

420

Automobile Collisions, Kinematics and Related Injury Patterns  

PubMed Central

It has been determined clinically that fatalities and injury severity resulting from automobile collisions have decreased during the last five years for low impact speeds. This reduction is a direct result of the application of biomechanics and occupant kinematics, as well as changes in automobile design. The paper defines terminology used in the field of mechanics and develops examples and illustrations of the physical concepts of acceleration, force strength, magnitude duration, rate of onset and others, as they apply to collision phenomena and injury. The mechanism of injury pattern reduction through the use of restraint systems is illustrated. PMID:5059661

Siegel, A. W.

1972-01-01

421

Mapping Dark Matter Halos with Stellar Kinematics  

NASA Astrophysics Data System (ADS)

Galaxies of all sizes form and evolve in the centers of dark matter halos. As these halos constitute the large majority of the total mass of a galaxy, dark matter certainly plays a central role in the galaxy's formation and evolution. Yet despite our understanding of the importance of dark matter, observations of the extent and shape of dark matter halos have been slow in coming. The paucity of data is particularly acute in elliptical galaxies. Happily, concerted effort over the past several years by a number of groups has been shedding light on the dark matter halos around galaxies over a wide range in mass. The development of new instrumentation and large surveys, coupled with the tantalizing evidence for a direct detection of dark matter from the AMS experiment, has brought on a golden age in the study of galactic scale dark matter halos. I report on results using extended stellar kinematics from integrated light to dynamically model massive elliptical galaxies in the local universe. I use the integral field power of the Mitchell Spectrograph to explore the kinematics of stars to large radii (R > 2.5 r_e). Once the line-of-sight stellar kinematics are measured, I employ orbit-based, axisymmetric dynamical modeling to explore a range of dark matter halo parameterizations. Globular cluster kinematics at even larger radii are used to further constrain the dynamical models. The dynamical models also return information on the anisotropy of the stars which help to further illuminate the primary formation mechanisms of the galaxy. Specifically, I will show dynamical modeling results for the first and second rank galaxies in the Virgo Cluster, M49 and M87. Although similar in total luminosity and ellipticity, these two galaxies show evidence for different dark matter halo shapes, baryon to dark matter fractions, and stellar anisotropy profiles. Moreover, the stellar velocity dispersion at large radii in M87 is significantly higher than the globular clusters at the same radial extent, reinforcing the need for broad comparisons between the different methods and assumptions underlying the dynamical analysis of massive ellipticals.

Murphy, Jeremy; Gebhardt, K.; Greene, J. E.; Graves, G.

2013-07-01

422

Overview of kinematic variables in top production  

SciTech Connect

A selection of simple kinematic variables chosen to be sensitive to different aspects of {ital t{anti t}} production in W + {>=} 3 jets events are studied. Monte Carlo comparisons are made between different top generators (Herwig, Pythia, and Isajet) and a QCD background generator (VECBOS). Finally, Monte Carlo predictions with the {ital t{anti t}} fraction constrained by the SVX {ital b}-tagging rate and measured top mass are compared with 110 pb{sup -1} of CDF data. We conclude that the CDF data is consistent with standard predictions using the studied generators.

Binkley, M.; Beretvas, A.; CDF Collaboration

1996-09-01

423

Kinematic Measurements from YouTube Videos  

NASA Astrophysics Data System (ADS)

Video analysis of motion has been in use now for some time.1-3 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. This paper provides examples such as measuring the average speed of a winning horse at the Kentucky Derby, plotting speed versus time from watching the speedometer of a high-performance bike, and determining acceleration for circular motion of amusement park rides.

Ruiz, Michael J.

2009-04-01

424

Quantum Simulation of Noncausal Kinematic Transformations  

NASA Astrophysics Data System (ADS)

We propose the implementation of Galileo group symmetry operations or, in general, linear coordinate transformations in a quantum simulator. With an appropriate encoding, unitary gates applied to our quantum system give rise to Galilean boosts or spatial and time parity operations in the simulated dynamics. This framework provides us with a flexible toolbox that enhances the versatility of quantum simulation theory, allowing the direct access to dynamical quantities that would otherwise require full tomography. Furthermore, this method enables the study of noncausal kinematics and phenomena beyond special relativity in a quantum controllable system.

Alvarez-Rodriguez, U.; Casanova, J.; Lamata, L.; Solano, E.

2013-08-01

425

Failure tolerant operation of kinematically redundant manipulators  

NASA Technical Reports Server (NTRS)

Redundant manipulators may compensate for failed joints with their additional degrees of freedom. In this paper such a manipulator is considered fault tolerant if it can guarantee completion of a task after any one of its joints has failed. This fault tolerance of kinematically redundant manipulators is insured here. Methods to analyze the manipulator's work space find regions inherently suitable for critical tasks because of their high level of failure tolerance. Constraints are then placed on the manipulator's range of motion to guarantee completion of a task.

Lewis, Christopher L.; Maciejewski, Anthony A.

1994-01-01

426

Quantum simulation of noncausal kinematic transformations.  

PubMed

We propose the implementation of Galileo group symmetry operations or, in general, linear coordinate transformations in a quantum simulator. With an appropriate encoding, unitary gates applied to our quantum system give rise to Galilean boosts or spatial and time parity operations in the simulated dynamics. This framework provides us with a flexible toolbox that enhances the versatility of quantum simulation theory, allowing the direct access to dynamical quantities that would otherwise require full tomography. Furthermore, this method enables the study of noncausal kinematics and phenomena beyond special relativity in a quantum controllable system. PMID:24033011

Alvarez-Rodriguez, U; Casanova, J; Lamata, L; Solano, E

2013-08-30

427

The Kinematics of Dwarf Spheroidal Galaxies  

E-print Network

I review observational data on the kinematic properties of dwarf spheroidal galaxies in the halo of the Milky Way and beyond. The present data confirm previous claims that these galaxies have unusually large central velocity dispersions. `Simple' sources of bias such as binary stars, internal atmospheric motions, measurement errors, and small sample sizes cannot explain the large dispersions measures in all dSph systems. Recent data suggest that in some of these dwarfs the veolocity dispersion profiles are flat out to their classical tidal radii. I discuss how these results can (or cannot) be understood by invoking a variety of distinct models, including classical dark matter halos, tidal disruption and MOND.

Mario Mateo

1997-01-21

428

Decentralized kinematics algorithm for modular space robots  

NASA Astrophysics Data System (ADS)

The Communications Research Laboratory has been studying the inspection technology needed for the first step of an Orbital Maintenance System (OMS) for maintaining space systems by inspecting satellites, re-orbiting useless satellites, and simply repairing satellites in orbit. OMS will use a modular manipulator for remote inspection. One of the most important issues concerning control of the modular manipulator is a determination process that utilizes its decentralized control architecture. In this paper, we introduce a decentralized kinematics control algorithm that automatically adapts to partial faults and reconfigures itself.

Kimura, Shinichi; Tsuchiya, Shigeru

2000-10-01

429

Inverse Compton Scattering in Mildly Relativistic Plasma  

NASA Technical Reports Server (NTRS)

We investigated the effect of inverse Compton scattering in mildly relativistic static and moving plasmas with low optical depth using Monte Carlo simulations, and calculated the Sunyaev-Zel'dovich effect in the cosmic background radiation. Our semi-analytic method is based on a separation of photon diffusion in frequency and real space. We use Monte Carlo simulation to derive the intensity and frequency of the scattered photons for a monochromatic incoming radiation. The outgoing spectrum is determined by integrating over the spectrum of the incoming radiation using the intensity to determine the correct weight. This method makes it possible to study the emerging radiation as a function of frequency and direction. As a first application we have studied the effects of finite optical depth and gas infall on the Sunyaev-Zel'dovich effect (not possible with the extended Kompaneets equation) and discuss the parameter range in which the Boltzmann equation and its expansions can be used. For high temperature clusters (k(sub B)T(sub e) greater than or approximately equal to 15 keV) relativistic corrections based on a fifth order expansion of the extended Kompaneets equation seriously underestimate the Sunyaev-Zel'dovich effect at high frequencies. The contribution from plasma infall is less important for reasonable velocities. We give a convenient analytical expression for the dependence of the cross-over frequency on temperature, optical depth, and gas infall speed. Optical depth effects are often more important than relativistic corrections, and should be taken into account for high-precision work, but are smaller than the typical kinematic effect from cluster radial velocities.

Molnar, S. M.; Birkinshaw, M.

1998-01-01

430

Kinematic Design to Improve Ergonomics in Human Machine Interaction  

Microsoft Academic Search

This paper introduces a novel kinematic design paradigm for ergonomic human machine interaction. Goals for optimal design are formulated generically and applied to the mechanical design of an upper-arm exoskeleton. A nine degree-of-freedom (DOF) model of the human arm kinematics is presented and used to develop, test, and optimize the kinematic structure of an human arm interfacing exoskeleton. The resulting

André Schiele; Frans C. T. van der Helm

2006-01-01

431

computational inverse medium scattering at fixed frequency  

E-print Network

A continuation method is presented for solving the inverse medium scattering problem of the. Helmholtz ... The inverse medium scattering problem is to determine the scatterer q(x) from the measurements ... layer of the medium is penetrated. ..... [7] Y. Chen, Inverse scattering via skin effect, Inverse Problems, 13 (1997), pp.

2005-12-08

432

Kinematics of signature writing in healthy aging.  

PubMed

Forensic document examiners (FDE) called upon to distinguish a genuine from a forged signature of an elderly person are often required to consider the question of age-related deterioration and whether the available exemplars reliably capture the natural effects of aging of the original writer. An understanding of the statistical relationship between advanced age and handwriting movements can reduce the uncertainty that may exist in an examiner's approach to questioned signatures formed by elderly writers. The primary purpose of this study was to systematically examine age-related changes in signature kinematics in healthy writers. Forty-two healthy subjects between the ages of 60-91 years participated in this study. Signatures were recorded using a digitizing tablet, and commercial software was used to examine the temporal and spatial stroke kinematics and pen pressure. Results indicated that vertical stroke duration and dysfluency increased with age, whereas vertical stroke amplitude and velocity decreased with age. Pen pressure decreased with age. We found that a linear model characterized the best-fit relationship between advanced age and handwriting movement parameters for signature formation. Male writers exhibited stronger age effects than female writers, especially for pen pressure and stroke dysfluency. The present study contributes to an understanding of how advanced age alters signature formation in otherwise healthy adults. PMID:24673648

Caligiuri, Michael P; Kim, Chi; Landy, Kelly M

2014-07-01

433

Nuclear Rings in Galaxies - A Kinematic Perspective  

NASA Technical Reports Server (NTRS)

We combine DensePak integral field unit and TAURUS Fabry-Perot observations of 13 nuclear rings to show an interconnection between the kinematic properties of the rings and their resonant origin. The nuclear rings have regular and symmetric kinematics, and lack strong non-circular motions. This symmetry, coupled with a direct relationship between the position angles and ellipticities of the rings and those of their host galaxies, indicate the rings are in the same plane as the disc and are circular. From the rotation curves derived, we have estimated the compactness (v(sup 2)/r) up to the turnover radius, which is where the nuclear rings reside. We find that there is evidence of a correlation between compactness and ring width and size. Radially wide rings are less compact, and thus have lower mass concentration. The compactness increases as the ring width decreases. We also find that the nuclear ring size is dependent on the bar strength, with weaker bars allowing rings of any size to form.

Mazzuca, Lisa M.; Swaters, Robert A.; Knapen, Johan H.; Veilleux, Sylvain

2011-01-01

434

The kinematics of turbulent boundary layer structure  

NASA Technical Reports Server (NTRS)

The long history of research into the internal structure of turbulent boundary layers has not provided a unified picture of the physics responsible for turbulence production and dissipation. The goals of the present research are to: (1) define the current state of boundary layer structure knowledge; and (2) utilize direct numerical simulation results to help close the unresolved issues identified in part A and to unify the fragmented knowledge of various coherent motions into a consistent kinematic model of boundary layer structure. The results of the current study show that all classes of coherent motion in the low Reynolds number turbulent boundary layer may be related to vortical structures, but that no single form of vortex is representative of the wide variety of vortical structures observed. In particular, ejection and sweep motions, as well as entrainment from the free-streem are shown to have strong spatial and temporal relationships with vortical structures. Disturbances of vortex size, location, and intensity show that quasi-streamwise vortices dominate the buffer region, while transverse vortices and vortical arches dominate the wake region. Both types of vortical structure are common in the log region. The interrelationships between the various structures and the population distributions of vortices are combined into a conceptual kinematic model for the boundary layer. Aspects of vortical structure dynamics are also postulated, based on time-sequence animations of the numerically simulated flow.

Robinson, Stephen Kern

1991-01-01

435

Optimization and geophysical inverse problems  

SciTech Connect

A fundamental part of geophysics is to make inferences about the interior of the earth on the basis of data collected at or near the surface of the earth. In almost all cases these measured data are only indirectly related to the properties of the earth that are of interest, so an inverse problem must be solved in order to obtain estimates of the physical properties within the earth. In February of 1999 the U.S. Department of Energy sponsored a workshop that was intended to examine the methods currently being used to solve geophysical inverse problems and to consider what new approaches should be explored in the future. The interdisciplinary area between inverse problems in geophysics and optimization methods in mathematics was specifically targeted as one where an interchange of ideas was likely to be fruitful. Thus about half of the participants were actively involved in solving geophysical inverse problems and about half were actively involved in research on general optimization methods. This report presents some of the topics that were explored at the workshop and the conclusions that were reached. In general, the objective of a geophysical inverse problem is to find an earth model, described by a set of physical parameters, that is consistent with the observational data. It is usually assumed that the forward problem, that of calculating simulated data for an earth model, is well enough understood so that reasonably accurate synthetic data can be generated for an arbitrary model. The inverse problem is then posed as an optimization problem, where the function to be optimized is variously called the objective function, misfit function, or fitness function. The objective function is typically some measure of the difference between observational data and synthetic data calculated for a trial model. However, because of incomplete and inaccurate data, the objective function often incorporates some additional form of regularization, such as a measure of smoothness or distance from a prior model. Various other constraints may also be imposed upon the process. Inverse problems are not restricted to geophysics, but can be found in a wide variety of disciplines where inferences must be made on the basis of indirect measurements. For instance, most imaging problems, whether in the field of medicine or non-destructive evaluation, require the solution of an inverse problem. In this report, however, the examples used for illustration are taken exclusively from the field of geophysics. The generalization of these examples to other disciplines should be straightforward, as all are based on standard second-order partial differential equations of physics. In fact, sometimes the non-geophysical inverse problems are significantly easier to treat (as in medical imaging) because the limitations on data collection, and in particular on multiple views, are not so severe as they generally are in geophysics. This report begins with an introduction to geophysical inverse problems by briefly describing four canonical problems that are typical of those commonly encountered in geophysics. Next the connection with optimization methods is made by presenting a general formulation of geophysical inverse problems. This leads into the main subject of this report, a discussion of methods for solving such problems with an emphasis upon newer approaches that have not yet become prominent in geophysics. A separate section is devoted to a subject that is not encountered in all optimization problems but is particularly important in geophysics, the need for a careful appraisal of the results in terms of their resolution and uncertainty. The impact on geophysical inverse problems of continuously improving computational resources is then discussed. The main results are then brought together in a final summary and conclusions section.

Barhen, J.; Berryman, J.G.; Borcea, L.; Dennis, J.; de Groot-Hedlin, C.; Gilbert, F.; Gill, P.; Heinkenschloss, M.; Johnson, L.; McEvilly, T.; More, J.; Newman, G.; Oldenburg, D.; Parker, P.; Porto, B.; Sen, M.; Torczon, V.; Vasco, D.; Woodward, N.B.

2000-10-01

436

Exploring the Hamiltonian inversion landscape.  

PubMed

The identification of quantum system Hamiltonians through the use of experimental data remains an important research goal. Seeking a Hamiltonian that is consistent with experimental measurements constitutes an excursion over a Hamiltonian inversion landscape, which is the quality of reproducing the data as a function of the Hamiltonian parameters. Recent theoretical work showed that with sufficient experimental data there should be local convexity about the true Hamiltonian on the landscape. The present paper builds on this result and performs simulations to test whether such convexity is observed. A gradient-based Hamiltonian search algorithm is incorporated into an inversion routine as a means to explore the local inversion landscape. The simulations consider idealized noise-free as well as noise-ridden experimental data. The results suggest that a sizable convex domain exists about the true Hamiltonian, even with a modest amount of experimental data and in the presence of a reasonable level of noise. PMID:24956139

Donovan, Ashley; Rabitz, Herschel

2014-08-01

437

Inversion of the star transform  

E-print Network

We define the star transform as a generalization of the broken ray transform introduced by us in previous work. The advantages of using the star transform include the possibility to reconstruct the absorption and the scattering coefficients of the medium separately and simultaneously (from the same data) and the possibility to utilize scattered radiation which, in the case of the conventional X-ray tomography, is discarded. In this paper, we derive the star transform from physical principles, discuss its mathematical properties and analyze numerical stability of inversion. In particular, it is shown that stable inversion of the star transform can be obtained only for configurations involving odd number of rays. Several computationally-efficient inversion algorithms are derived and tested numerically.

Fan Zhao; John C. Schotland; Vadim A. Markel

2014-05-06

438

Inversion of the star transform  

NASA Astrophysics Data System (ADS)

We define the star transform as a generalization of the broken ray transform introduced by us in previous work. The advantages of using the star transform include the possibility to reconstruct the absorption and the scattering coefficients of the medium separately and simultaneously (from the same data) and the possibility to utilize scattered radiation which, in the case of conventional x-ray tomography, is discarded. In this paper, we derive the star transform from physical principles, discuss its mathematical properties and analyze numerical stability of inversion. In particular, it is shown that stable inversion of the star transform can be obtained only for configurations involving odd number of rays. Several computationally-efficient inversion algorithms are derived and tested numerically.

Zhao, Fan; Schotland, John C.; Markel, Vadim A.

2014-10-01

439

Kinematic modeling of a double octahedral Variable Geometry Truss (VGT) as an extensible gimbal  

NASA Technical Reports Server (NTRS)

This paper presents the complete forward and inverse kinematics solutions for control of the three degree-of-freedom (DOF) double octahedral variable geometry truss (VGT) module as an extensible gimbal. A VGT is a truss structure partially comprised of linearly actuated members. A VGT can be used as joints in a large, lightweight, high load-bearing manipulator for earth- and space-based remote operations, plus industrial applications. The results have been used to control the NASA VGT hardware as an extensible gimbal, demonstrating the capability of this device to be a joint in a VGT-based manipulator. This work is an integral part of a VGT-based manipulator design, simulation, and control tool.

Williams, Robert L., II

1994-01-01

440

Probabilistic inversion: a preliminary discussion  

NASA Astrophysics Data System (ADS)

We continue the discussion on the possibility of interpreting probability as a logic, that we have started in the previous IMEKO TC1-TC7-TC13 Symposium. We show here how a probabilistic logic can be extended up to including direct and inverse functions. We also discuss the relationship between this framework and the Bayes-Laplace rule, showing how the latter can be formally interpreted as a probabilistic inversion device. We suggest that these findings open a new perspective in the evaluation of measurement uncertainty.

Battista Rossi, Giovanni; Crenna, Francesco

2015-02-01

441

Darwin's “strange inversion of reasoning”  

PubMed Central

Darwin's theory of evolution by natural selection unifies the world of physics with the world of meaning and purpose by proposing a deeply counterintuitive “inversion of reasoning” (according to a 19th century critic): “to make a perfect and beautiful machine, it is not requisite to know how to make it” [MacKenzie RB (1868) (Nisbet & Co., London)]. Turing proposed a similar inversion: to be a perfect and beautiful computing machine, it is not requisite to know what arithmetic is. Together, these ideas help to explain how we human intelligences came to be able to discern the reasons for all of the adaptations of life, including our own. PMID:19528651

Dennett, Daniel

2009-01-01

442

Deployable antenna kinematics using tensegrity structure design  

NASA Astrophysics Data System (ADS)

With vast changes in spacecraft development over the last decade, a new, cheaper approach was needed for deployable kinematic systems such as parabolic antenna reflectors. Historically, these mesh-surface reflectors have resembled folded umbrellas, with incremental redesigns utilized to save packaging size. These systems are typically over-constrained designs, the assumption being that high reliability necessary for space operations requires this level of conservatism. But with the rapid commercialization of space, smaller launch platforms and satellite buses have demanded much higher efficiency from all space equipment than can be achieved through this incremental approach. This work applies an approach called tensegrity to deployable antenna development. Kenneth Snelson, a student of R. Buckminster Fuller, invented Tensegrity structures in 1948. Such structures use a minimum number of compression members (struts); stability is maintain using tension members (ties). The novelty introduced in this work is that the ties are elastic, allowing the struts to extend or contract, and in this way changing the surface of the antenna. Previously, the University of Florida developed an approach to quantify the stability and motion of parallel manipulators. This approach was applied to deployable, tensegrity, antenna structures. Based on the kinematic analyses for the 3-3 (octahedron) and 4-4 (square anti-prism) structures, the 6-6 (hexagonal anti-prism) analysis was completed which establishes usable structural parameters. The primary objective for this work was to prove the stability of this class of deployable structures, and their potential application to space structures. The secondary objective is to define special motions for tensegrity antennas, to meet the subsystem design requirements, such as addressing multiple antenna-feed locations. This work combines the historical experiences of the artist (Snelson), the mathematician (Ball), and the space systems engineer (Wertz) to develop a new, practical design approach. This kinematic analysis of tensegrity structures blends these differences to provide the design community with a new approach to lightweight, robust, adaptive structures with the high reliability that space demands. Additionally, by applying Screw Theory, a tensegrity structure antenna can be commanded to move along a screw axis, and therefore meeting the requirement to address multiple feed locations.

Knight, Byron Franklin

443

Inverse control of nonlinear systems using neural network observer and inverse mapping approach  

Microsoft Academic Search

This paper introduces a new approach to inverse control. Unlike using commonly known method of plant inverse dynamics learning, the control sequence is calculated using inverse mapping approach. Both methods are compared with nonlinear plant examples and selected desired waveforms

Aleksander Malinowski; Jacek M. Zurada; John H. Lilly

1995-01-01

444

Visual Servoing Using Projective Kinematics Andreas Ruf1  

E-print Network

to classical approaches, the entire system is modeled by means of projective geometry. For the robot's geometryVisual Servoing Using Projective Kinematics Andreas Ruf1 , Fr´ed´erick Martin2 , Bart Lamiroy3 in particular, we introduce a new formalism "projective kinematics". As a result, motions in joint- and image

Paris-Sud XI, Université de

445

Lingual Kinematics during Rapid Syllable Repetition in Parkinson's Disease  

ERIC Educational Resources Information Center

Background: Rapid syllable repetition tasks are commonly used in the assessment of motor speech disorders. However, little is known about the articulatory kinematics during rapid syllable repetition in individuals with Parkinson's disease (PD). Aims: To investigate and compare lingual kinematics during rapid syllable repetition in dysarthric…

Wong, Min Ney; Murdoch, Bruce E.; Whelan, Brooke-Mai

2012-01-01

446

A School Experiment in Kinematics: Shooting from a Ballistic Cart  

ERIC Educational Resources Information Center

Many physics textbooks start with kinematics. In the lab, students observe the motions, describe and make predictions, and get acquainted with basic kinematics quantities and their meaning. Then they can perform calculations and compare the results with experimental findings. In this paper we describe an experiment that is not often done, but is…

Kranjc, T.; Razpet, N.

2011-01-01

447