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1

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

2

Examples of planar robot kinematic designs from optimally fault-tolerant Jacobians  

Microsoft Academic Search

It is common practice to design a robot's kinemat- ics from the desired properties that are locally specified by a manipulator Jacobian. It has been recently shown that multiple different physical robot kinematic designs can be obtained from (essentially) a single Jacobian that has desirable fault tolerant properties (1). Fault tolerance in this case is defined as the post-failure Jacobian

Khaled M. Ben-Gharbia; Rodney G. Roberts; Anthony A. Maciejewski

2011-01-01

3

Examples of planar robot kinematic designs from optimally fault-tolerant Jacobians  

E-print Network

Examples of planar robot kinematic designs from optimally fault-tolerant Jacobians Khaled M. Ben-- It is common practice to design a robot's kinemat- ics from the desired properties that are locally specified by a manipulator Jacobian. It has been recently shown that multiple different physical robot kinematic designs can

Maciejewski, Anthony A.

4

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

5

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

6

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

7

Inverse differential kinematics Prof. Alessandro De Luca  

E-print Network

Robotics 1 Inverse differential kinematics Statics Prof. Alessandro De Luca Robotics 1 1 #12;Inversion of differential kinematics ! find the joint velocity vector that realizes a desired end- effector by inversion of a given Cartesian motion task ! figure shows a linear Cartesian trajectory for a planar 2R

De Luca, Alessandro

8

Bootstrapping inverse kinematics with Goal Babbling  

Microsoft Academic Search

We present an approach to learn inverse kinematics of redundant systems without prior- or expert-knowledge. The method allows for an iterative bootstrapping and refinement of the inverse kinematics estimate. We show that the information structure induced by goal-directed exploration enables an efficient resolution of inconsistent samples solely from observable data. The bootstrapped solutions are aligned for a maximum of movement

Matthias Rolf; Jochen J. Steil; Michael Gienger

2010-01-01

9

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

10

Inverse Kinematics for Modular Reconfigurable Robots  

Microsoft Academic Search

Inverse kinematics solutions of a reconfig- urabie robot system built upon a collection of standard- ized components is dificult to obtain because of its vary- ing configuration. This paper addresses the formulation of a generic numerical inverse kinematics model and au- tomatic generation of the model for arbitrary robot ge- ometry including serial type and branching type geome- try. Both

I-ming Chen; Guilin Yang

1998-01-01

11

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

12

Pseudo-inverse Jacobian control with grey relational analysis for robot manipulators mounted on oscillatory bases  

NASA Astrophysics Data System (ADS)

Interest in complex robotic systems is growing in new application areas. An example of such a robotic system is a dexterous manipulator mounted on an oscillatory base. In literature, such systems are known as macro/micro systems. This work proposes pseudo-inverse Jacobian feedback control laws and applies grey relational analysis for tuning outer-loop PID control parameters of Cartesian computed-torque control law for robotic manipulators mounted on oscillatory bases. The priority when modifying controller parameters should be the top ranking importance among parameters. Grey relational grade is utilized to investigate the sensitivity of tuning the auxiliary signal PID of the Cartesian computed-torque law to achieve desired performance. Results of this study can be feasible to numerous mechanical systems, such as mobile robots, gantry cranes, underwater robots, and other dynamic systems mounted on oscillatory bases, for moving the end-effector to a desired Cartesian position.

Lin, J.; Lin, C. C.; Lo, H.-S.

2009-10-01

13

EFFICIENT INVERSE KINEMATICS ALGORITHM BASED ON CONFORMAL GEOMETRIC ALGEBRA  

E-print Network

EFFICIENT INVERSE KINEMATICS ALGORITHM BASED ON CONFORMAL GEOMETRIC ALGEBRA Using Reconfigurable@esa.informatik.tu-darmstadt.de Keywords: geometric algebra, geometric computing, computer animation, inverse kinematics, hardware approach for algorithms developed based on conformal geometric algebra using reconfigurable hardware. We

14

A PLANAR PARALLEL MANIPULATOR WITH HOLONOMIC HIGHER PAIRS: INVERSE KINEMATICS  

E-print Network

A PLANAR PARALLEL MANIPULATOR WITH HOLONOMIC HIGHER PAIRS: INVERSE KINEMATICS Matthew John D. HAYES kinematic analysis. Very little literature on such planar mechanisms was found. The e ects of initial. Furthermore, inverse kinematic (IK) solutions are necessary to plan trajectories and avoid obstacles

Hayes, John

15

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

16

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

17

Minimum Infinity-Norm Inverse Kinematic Solution For Redundant Manipulators  

Microsoft Academic Search

Redundant manipulators admit infinite solutions to the inverse kinematic problem for given end-effector parameters. The problem of determining a minimum infinity norm solution to the velocity inverse kinematic problem, i.e., computing a joint velocity vector whose maximum absolute value component is minimum among all joint velocity vectors yielding the desired end-effector velocity, is investigated. The proposed method uses duality results

Arati S. Deo; Ian D. Walker

1993-01-01

18

A complete generalized solution to the inverse kinematics of robots  

Microsoft Academic Search

The kinematic transformation between task space and joint configuration coordinates is nonlinear and configuration dependent. A solution to the inverse kinematics is a vector of joint configuration coordinates that corresponds to a set of task space coordinates. For a class of robots closed form solutions always exist, but constraints on joint displacements cannot be systematically incorporated in the process of

ANDREW A. GOLDENBERG; B. Benhabib; ROBERT G. FENTON

1985-01-01

19

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

20

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

21

Inverse kinematic and dynamic analysis of a 3DOF parallel mechanism  

Microsoft Academic Search

This paper presents the inverse kinematic and dynamic analyses of the 3UPS-UP parallel mechanism with three degrees of freedom. For inverse kinematics, the kinematic constraint equations of the movable platform are established according to the structural character of the passive sub-chain, based on which the closed-form inverse kinematic formulas of the mechanism are obtained. In inverse dynamic analysis, the mechanism

Jianfeng Li; Weihai Chen; Dezhong Liul; Jinsong Wang

2002-01-01

22

A parallel inverse kinematics solution for robot manipulators based on multiprocessing and linear extrapolation  

Microsoft Academic Search

A method of computing inverse kinematics in parallel for robots with a closed-form solution is presented. The computational task of computing each inverse kinematics solution is partitioned with one subtask per joint, and all subtasks are computed concurrently. The intrinsic dependency among subtasks is removed by linear extrapolation through the gradient of inverse kinematic functions and joint velocity information. The

H. Zhang; R. P. Paul

1990-01-01

23

INVERSE KINEMATICS AND DYNAMICS ANALYSIS OF A THREE LEGGED PARALLEL MECHANISM ACTUATED BY AGVs  

E-print Network

1 INVERSE KINEMATICS AND DYNAMICS ANALYSIS OF A THREE LEGGED PARALLEL MECHANISM ACTUATED BY AGVs kinematics and inverse dynamics analysis of a parallel mechanism is presented. The mechanism consists configuration. Inverse kinematics and dynamics analysis is also performed for the three actuators (mobile robots

Saha, Subir Kumar

24

Missile guidance algorithm design using inverse kinematics and fuzzy logic  

Microsoft Academic Search

This is a feasibility study of using fuzzy logic to guide an air-to-surface missile against a stationary target. The guidance algorithm design specifications are (1) a smooth transition at lock-on, (2) inherent acceleration command limits and (3) large impact angles. Inverse kinematics is used to design the fuzzy guidance algorithm so that all three requirements are satisfied. A comparison with

Gerard Leng

1996-01-01

25

Node Allocation and Topographical Encoding (NATE) for Inverse Kinematics of a Redundant Robot Arm  

E-print Network

kinematics (DIK) of a planar 4-joint manipulator (4JM). Let 2 IR 4 be the vector of joint angles, and r 2 IRNode Allocation and Topographical Encoding (NATE) for Inverse Kinematics of a Redundant Robot Arm){311{4597 FAX: (211){311{3085 Internet: haki@biokyb.uni-duesseldorf.de Abstract The local inverse kinematics

Behnke, Sven

26

Comparative Analysis for the Inverse Kinematics of Redundant Manipulators based on Repetitive Tracking Tasks  

E-print Network

Comparative Analysis for the Inverse Kinematics of Redundant Manipulators based on Repetitive(DoF) of open loop kinematic chain, the closed-loop inverse kinematics algorithm(CLIK) via pseudoinverse method. The repetitive trajectories are tracked in the simulations made on the 3-DoF planar and 4-DoF spatial

Li, Yangmin

27

Robust Modular Inverse Kinematics for Gesture Imitation in an Upper-Body Humanoid Robot  

E-print Network

Robust Modular Inverse Kinematics for Gesture Imitation in an Upper-Body Humanoid Robot Keng Peng of computing the joint angles for an upper body humanoid robot correspond- ing to task space motion data from units, and solve the inverse kinematics in a modular fashion based on the derivative of the inverse

Huang, Zhiyong

28

Proton inelastic scattering on {sup 56}Ni in inverse kinematics  

SciTech Connect

Inelastic proton scattering to the first excited 2{sup +} state at 2.701 MeV in doubly magic {sup 56}Ni was studied at 101 MeV/u in inverse kinematics. The radioactive {sup 56}Ni ion beam was obtained from the SIS heavy ion synchrotron at GSI Darmstadt via fragmentation of a {sup 58}Ni beam, and separation by the fragment separator (FRS). A value B(E2, 0{sup +} {yields} 2{sup +}) = 600 {+-} 120 e{sup 2} fm{sup 4} was obtained which corresponds to a deformation parameter {beta} ({sup 56}Ni) = 0.173 {+-} 0.017.

Kraus, G.; Egelhof, P.; Fischer, C.; Geissel, H.; Himmler, A.; Nickel, F.; Muenzenberg, G.; Schwab, W.; Weiss, A. [GSI, Darmstadt (Germany); Chulkov, L.; Golovkov, M.; Ogloblin, A. [I.V. Kurchatov Inst., Moscow (Russian Federation); Friese, J.; Gillitzer, A.; Koerner, H.J.; Peter, M. [TU, Munich (Germany); Henning, W.; Schiffer, J.P. [Argonne National Lab., IL (United States); Kratz, J.V. [Univ. of Mainz (Germany)

1993-10-01

29

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

Xinyao Hu; Gim Song Soh

2014-08-01

30

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

31

On Inverse Kinematics and Trajectory Planning for Tele-Laparoscopic Manipulation  

Microsoft Academic Search

Addresses the kinematic modelling, solutions and trajectory planning of a tele-laparoscopic manipulator. This type of manipulator can be used in remote positioning of laparoscopic tools through a tele-operating system. Specifically the paper models kinematics of a typical manipulating system which can be used in such tele-surgery. Inverse kinematics solutions are also obtained for two kinematically constrained motions which are part

Ali Faraz; Shahram Payandeh

1999-01-01

32

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

33

A new and efficient algorithm for the inverse kinematics of a general serial 6 R manipulator  

Microsoft Academic Search

In this paper a new and very efficient algorithm to compute the inverse kinematics of a general 6R serial kinematic chain is presented. The main idea is to make use of classical multidimensional geometry to structure the problem and to use the geometric information before starting the elimination process. For the geometric pre-processing we utilize the Study model of Euclidean

Manfred L. Husty; Martin Pfurner; Hans-Peter Schröcker

2007-01-01

34

Solution of inverse kinematic problem for serial robot using dual quaterninons and plücker coordinates  

Microsoft Academic Search

In this paper we present a new formulation method to solve kinematic problem of serial robot manipulators. In this method our major aims are to formulize inverse kinematic problem in a compact closed form and to avoid singularity problem. This formulation is based on screw theory with dual - quaternion. Compared with other methods, screw theory methods just establish two

E. Sariyildiz; H. Temeltas

2009-01-01

35

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

36

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

37

Joint coseismic and postseismic kinematic slip inversions in a Bayesian framework (Invited)  

Microsoft Academic Search

The classic linear, kinematic, static slip inversion of geodetic data requires specification of a smoothing norm of slip parameters, a residual norm of the data, and a choice about the relative weight between the two norms and the relative weights of multiple data sets. Inversions for unknown fault geometry are nonlinear and therefore the fault geometry is often assumed to

K. M. Johnson; J. Fukuda; J. Sun

2010-01-01

38

Inverse kinematics, fixation and grasping using conformal geometric algebra  

Microsoft Academic Search

In this paper the authors introduce the conformal geometric algebra in the field of visually guided robotics. As opposite to the standard projective geometry, we can deal simultaneously with incidence algebra operations and conformal transformations. As a result this framework appears promising for dealing with kinematics, dynamics and projective geometry problems without the need to abandon the mathematical system (as

Julio Zamora; Eduardo Bayro-Corrochano

2004-01-01

39

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

40

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

41

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

42

A RANDOM MATRIX APPROACH TO MANIPULATOR JACOBIAN Javad Sovizi  

E-print Network

: aalamdar@buffalo.edu vkrovi@buffalo.edu ABSTRACT Traditional kinematic analysis of manipulators, built upon of the uncertainty in the Jacobian matrix. Cheah et al. [11] investigated the kinematic as well as dynamic uncertainties in tracking control of the robot end effector (EE). The uncertain kinematic and dynamic parameters

Krovi, Venkat

43

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

44

Efficient Inverse Kinematics Algorithm Based on Conformal Geometric Algebra - Using Reconfigurable Hardware  

Microsoft Academic Search

configurable hardware, runtime performance. Abstract: This paper presents a very efficient approach for algorithms developed based on conformal geometric algebra using reconfigurable hardware. We use the inverse kinematics of the arm of a virtual human as an example, but we are convinced that this approach can be used in a wide field of computer animation applications. We describe the original

Dietmar Hildenbrand; Holger Lange; Florian Stock; Andreas Koch

2008-01-01

45

Control-Based Solution to Inverse Kinematics for Mobile Manipulators Using Penalty Functions  

Microsoft Academic Search

This study offers the solution at the control feedback level to the inverse kinematics problem subject to state equality and inequality constraints for mobile manipulators. Based on the Lyapunov stability theory, a class of controllers generating the mobile manipulator trajectory whose attractor attained in a finite time, fulfills the above state constraints. The problem of both holonomic manipulability enforcement and

Miroslaw Galicki

2005-01-01

46

Real-time neuromorphic algorithms for inverse kinematics of redundant manipulators  

NASA Technical Reports Server (NTRS)

The paper presents an efficient neuromorphic formulation to accurately solve the inverse kinematics problem for redundant manipulators. The approach involves a dynamical learning procedure based on a novel formalism in neural network theory: the concept of 'terminal' attractors. Topographically mapped terminal attractors are used to define a neural network whose synaptic elements can rapidly encapture the inverse kinematics transformations, and, subsequently generalize to compute joint-space coordinates required to achieve arbitrary end-effector configurations. Unlike prior neuromorphic implementations, this technique can also systematically exploit redundancy to optimize kinematic criteria, e.g., torque optimization. Simulations on 3-DOF and 7-DOF redundant manipulators, are used to validate the theoretical framework and illustrate its computational efficacy.

Barhen, Jacob; Gulati, Sandeep; Zak, Michail

1989-01-01

47

Solution of Inverse Kinematics for 6R Robot Manipulators With Offset Wrist Based on Geometric Algebra.  

PubMed

In this paper, we present an efficient method based on geometric algebra for computing the solutions to the inverse kinematics problem (IKP) of the 6R robot manipulators with offset wrist. Due to the fact that there exist some difficulties to solve the inverse kinematics problem when the kinematics equations are complex, highly nonlinear, coupled and multiple solutions in terms of these robot manipulators stated mathematically, we apply the theory of Geometric Algebra to the kinematic modeling of 6R robot manipulators simply and generate closed-form kinematics equations, reformulate the problem as a generalized eigenvalue problem with symbolic elimination technique, and then yield 16 solutions. Finally, a spray painting robot, which conforms to the type of robot manipulators, is used as an example of implementation for the effectiveness and real-time of this method. The experimental results show that this method has a large advantage over the classical methods on geometric intuition, computation and real-time, and can be directly extended to all serial robot manipulators and completely automatized, which provides a new tool on the analysis and application of general robot manipulators. PMID:23918347

Fu, Zhongtao; Yang, Wenyu; Yang, Zhen

2013-08-01

48

Probabilistic inversion of a kinematic source scenario including rotational ground motion measurements  

NASA Astrophysics Data System (ADS)

Since modern ring laser devices - originally developed to monitor changes in Earth's rotation rate - measure seismically induced rotational ground motions with high accuracy, numerous seismic studies successfully included the new observable. In this project we analyse the potential of rotational ground motions to contribute to better resolved parameters in kinematic source inversions. We aim to invert for the finite source characteristics of the 2000 Tottori earthquake (moment magnitude 6.7). The parameters we take into account are slip velocity, rise time and rupture time. Due to the general lack of rotational ground motion data in the context of kinematic source inversions we perform a synthetic study that also facilitates the control of uncertainties in both forward modelling and observations. We compute translational and rotational ground motions for a left-lateral strike-slip event representing the fault plane by an array of point sources in a 1-D Earth model. For the inversion process we apply a probabilistic approach. Sampling the model space with a Metropolis-Hastings algorithm provides the posterior probability density functions corresponding to the free parameters. We use the so called Shannon's measure of information content to compare the information gain of the results including rotational data to those exclusively based on translational ground motion measurements. This demonstrates that the incorporation of rotational ground motions can significantly improve the resolution in kinematic source inversions. However, the benefit from the new observable depends strongly on the signal to noise ratio in the rotational data.

Bernauer, M.; Igel, H.; Fichtner, A.

2013-12-01

49

Cortical Network Modeling for Inverse Kinematic Computation of an Anthropomorphic Finger  

PubMed Central

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.

2014-01-01

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

International Journal of Automation and Computing 2 (2005) 114-124 An Analysis of the Inverse Kinematics for a  

E-print Network

Kinematics for a 5-DOF Manipulator De Xu , Carlos A. Acosta Calderon, John Q. Gan, Huosheng Hu Department: This paper proposes an analytical solution for a 5-DOF manipulator to follow a given trajectory while keeping and control, 5-DOF manipulator. 1 Introduction Analytical techniques to deal with inverse kinemat- ics have

Hu, Huosheng

53

A complete analytical solution for the inverse instantaneous kinematics of a spherical-revolute-spherical (7R) redundant manipulator  

NASA Technical Reports Server (NTRS)

Using a method based upon resolving joint velocities using reciprocal screw quantities, compact analytical expressions are generated for the inverse solution of the joint rates of a seven revolute (spherical-revolute-spherical) manipulator. The method uses a sequential decomposition of screw coordinates to identify reciprocal screw quantities used in the resolution of a particular joint rate solution, and also to identify a Jacobian null-space basis used for the direct solution of optimal joint rates. The results of the screw decomposition are used to study special configurations of the manipulator, generating expressions for the inverse velocity solution for all non-singular configurations of the manipulator, and identifying singular configurations and their characteristics. Two functions are therefore served: a new general method for the solution of the inverse velocity problem is presented; and complete analytical expressions are derived for the resolution of the joint rates of a seven degree of freedom manipulator useful for telerobotic and industrial robotic application.

Podhorodeski, R. P.; Fenton, R. G.; Goldenberg, A. A.

1989-01-01

54

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

55

Creation of Thin Deuterated Polyethylene Targets for Inverse Kinematics Transfer Reaction Measurements  

NASA Astrophysics Data System (ADS)

Transfer reactions are an important tool for the study of single-particle structure of nuclei. Such measurements have many applications to the field of astrophysics, such as study of the rapid neutron capture (r-) process that is believed to create heavy elements in supernovae. Measurements in inverse kinematics are necessary when studying transfer reactions on unstable nuclei with lifetimes too short to be used as targets. The measurement of deuteron-induced transfer reactions in inverse kinematics requires a target containing a significant quantity of deuterons, such as deuterated polyethylene ((C2D4)n or CD2), which can be fabricated into thin foils by dissolving CD2 in xylene. A campaign is underway at ORNL to measure (d,p) reactions with unique heavy fission fragment beams. For such measurements, thin targets are favored to minimize peak broadening in the energy spectra of emitted particles. Emphasis has been placed on creation of targets of ˜70 ?g/cm^2 thickness, significantly thinner than previously used at ORNL. Improvements, such as careful control of the temperature of slides covered by the CD2/xylene solution, have been developed to produce such targets. Details will be presented. This research is supported by the Office of Nuclear Physics in the U. S. Department of Energy.

Long, K. D.; Kozub, R. L.; Manning, B.; Pain, S. D.; Nesaraja, C. D.; Smith, M. S.; Bardayan, D. W.

2011-10-01

56

Integrated Analytic and Linearized Inverse Kinematics for Precise Full Body Interactions  

NASA Astrophysics Data System (ADS)

Despite the large success of games grounded on movement-based interactions the current state of full body motion capture technologies still prevents the exploitation of precise interactions with complex environments. This paper focuses on ensuring a precise spatial correspondence between the user and the avatar. We build upon our past effort in human postural control with a Prioritized Inverse Kinematics framework. One of its key advantage is to ease the dynamic combination of postural and collision avoidance constraints. However its reliance on a linearized approximation of the problem makes it vulnerable to the well-known full extension singularity of the limbs. In such context the tracking performance is reduced and/or less believable intermediate postural solutions are produced. We address this issue by introducing a new type of analytic constraint that smoothly integrates within the prioritized Inverse Kinematics framework. The paper first recalls the background of full body 3D interactions and the advantages and drawbacks of the linearized IK solution. Then the Flexion-EXTension constraint (FLEXT in short) is introduced for the partial position control of limb-like articulated structures. Comparative results illustrate the interest of this new type of integrated analytical and linearized IK control.

Boulic, Ronan; Raunhardt, Daniel

57

Landslide Kinematical Analysis through Inverse Numerical Modelling and Differential SAR Interferometry  

NASA Astrophysics Data System (ADS)

The aim of this paper is to propose a methodology to perform inverse numerical modelling of slow landslides that combines the potentialities of both numerical approaches and well-known remote-sensing satellite techniques. In particular, through an optimization procedure based on a genetic algorithm, we minimize, with respect to a proper penalty function, the difference between the modelled displacement field and differential synthetic aperture radar interferometry (DInSAR) deformation time series. The proposed methodology allows us to automatically search for the physical parameters that characterize the landslide behaviour. To validate the presented approach, we focus our analysis on the slow Ivancich landslide (Assisi, central Italy). The kinematical evolution of the unstable slope is investigated via long-term DInSAR analysis, by exploiting about 20 years of ERS-1/2 and ENVISAT satellite acquisitions. The landslide is driven by the presence of a shear band, whose behaviour is simulated through a two-dimensional time-dependent finite element model, in two different physical scenarios, i.e. Newtonian viscous flow and a deviatoric creep model. Comparison between the model results and DInSAR measurements reveals that the deviatoric creep model is more suitable to describe the kinematical evolution of the landslide. This finding is also confirmed by comparing the model results with the available independent inclinometer measurements. Our analysis emphasizes that integration of different data, within inverse numerical models, allows deep investigation of the kinematical behaviour of slow active landslides and discrimination of the driving forces that govern their deformation processes.

Castaldo, R.; Tizzani, P.; Lollino, P.; Calò, F.; Ardizzone, F.; Lanari, R.; Guzzetti, F.; Manunta, M.

2014-12-01

58

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

59

Evaluating the effect of network density and geometric distribution on kinematic source inversion models  

NASA Astrophysics Data System (ADS)

The effect of network density and geometric distribution on kinematic non-linear source inversion is investigated by inverting synthetic ground motions from a buried strike-slip fault (Mw 6.5), that have been generated by dynamic spontaneous rupture modelling. For the inversion, we use a physics-based regularized Yoffe function as slip velocity function. We test three different cases of station network geometry: (i) single station, varying azimuth and epicentral distance; (ii) multistation circular configurations, that is stations at similar distances from the fault, and regularly spaced around the fault; (iii) irregular multistation configurations using different numbers of stations. Our results show: (1) single station tests suggest that it may be possible to obtain a relatively good source model even using a single station. The best source model using a single station is obtained with stations at which amplitude ratios between three components are not large. We infer that both azimuthal angle and source-to-station distance play an important role in the design of optimal seismic network for source inversion. (2) Multistation tests show that the quality of the inverted source systematically correlates neither with the number of stations, nor with waveform misfit. (3) Waveform misfit has a direct correlation with the number of stations, resulting in overfitting the observed data without any systematic improvement of the source. It suggests that the best source model is not necessarily derived from the model with minimum waveform misfit. (4) A seismic network with a small number of well-spaced stations around the fault may be sufficient to obtain acceptable source inversion.

Zhang, Youbing; Dalguer, Luis A.; Song, Seok Goo; Clinton, John; Giardini, Domenico

2015-01-01

60

Comparison of RBF and MLP neural networks to solve inverse kinematic problem for 6R serial robot by a fusion approach  

Microsoft Academic Search

In this paper, a fusion approach to determine inverse kinematics solutions of a six degree of freedom serial robot is proposed. The proposed approach makes use of radial basis function neural network for prediction of incremental joint angles which in turn are transformed into absolute joint angles with the assistance of forward kinematics relations. In this approach, forward kinematics relations

Shital S. Chiddarwar; N. Ramesh Babu

2010-01-01

61

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

62

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

63

MUST II: Large solid angle light charged particle telescope for inverse kinematics studies with radioactive beams  

SciTech Connect

Over the past four years we have studied (p,p'), (d,p) ,(d,3He) and other reactions using radioactive beams in inverse kinematics to obtain spectroscopic information for nuclei away from the valley of stability After a general overview of the experimental method we will describe our ongoing MUST II development. This is to build a very compact (1000cm3) three stage telescope with an active area of 100cm2 with position resolution of 0.7x0.7 mm2 and time of flight measurement. The mass identification and energy dynamic range is of 0.4 to 80 MeV.A up to alpha particles. The compactness of the array is assured through the use of an ASIC development to measure the time of flight and energy. The large solid angle coverage of 2.6sr and compactness of this array will allow it to be used in particle-gamma coincidence experiments.

Pollacco, E.; Atkin, E.; Auger, F.; Baron, P.; Drouart, A.; Rouger, M. [DSM/DAPNIA/SPhN, CEA Saclay, 91191Gif-sur-Yvette (France); Baronick, J.P.; Blumenfeld, Y.; Edelbruck, P.; Lavergne, L.; Leterrier, L.; Richard, A.; Wanlin, E. [Institut de Physique Nucleaire, IN2P3-CNRS, 91406 Orsay (France); Boujrad, A.; Olivier, L.; Raine, B.; Roussel-Chomaz, P.; Saillant, F.; Tripon, M. [GANIL, IN2P3-CNRS/DSM-CEA, BP 55027, 14021 Caen Cedex 5 (France)

2003-08-26

64

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

65

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

66

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

67

A unified fuzzy logic approach to trajectory planning and inverse kinematics for a fire fighting robot operating in tunnels  

Microsoft Academic Search

In this paper a fuzzy logic approach to automatic trajectory planning and closed-loop inverse kinematics for a robotic system\\u000a purposely designed to extinguish fires in road and railway tunnels is presented. The robot is composed of a self-cooling monorail\\u000a vehicle carrying a fire fighting monitor. A fuzzy inference system is adopted for the automatic generation of the task-space\\u000a trajectory for

A. De Santis; B. Siciliano; L. Villani

2008-01-01

68

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

69

Restricted Jacobian Matrices of Redundant Manipulators in Constrained Motion Tasks  

Microsoft Academic Search

Kinematically redundant manipulators are considered, with a prespecified end-effector task and multiple additional tasks. The number of additional tasks is assumed to be equal to or less than the degree of redundancy. This assumption justifies an equal-priority (or duality) concept for the end-effector task and additional tasks. Based on this concept, expressions for two restricted Jacobian matrices are derived: the

Dragomir N. Nenchev

1992-01-01

70

Development of a kinematically focused neutron source with the p(7Li,n)7Be inverse reaction  

NASA Astrophysics Data System (ADS)

Directional beams of neutrons can be produced, if a nuclear reaction, which emits neutrons, is initiated in inverse kinematics with a heavy ion projectile bombarding a light target. In this paper we investigate the use of the p(7Li,n)7Be inverse reaction to produce kinematically focused, quasi-mono-energetic neutron beams with a view to develop such an unusual neutron source for fundamental and applied nuclear physics studies. An experiment was carried out to validate the concept and to test the viability of two types of hydrogen-rich solid targets: polypropylene and TiH2. Neutron time-of-flight/energy spectra at 3 m distance from the source have been measured at 7Li bombarding energies of 13.5, 15, 15.5, 16, and 17 MeV, and neutron backgrounds from parasitic reactions have been characterized. The neutron angular distribution in the laboratory has been measured at 15 MeV. A Monte-Carlo code based on two-body relativistic kinematics has been developed and validated by comparison with the experimental data. Code-based extrapolations have then been used to deduce neutron energy spectra and maximum neutron fluxes available for future irradiation of samples placed in the neutron beam at small distances. For neutrons produced with thin (4 ?m) and thick (28 ?m) polypropylene targets the maximum available fluxes are calculated to be 107n/s/sr and 7×107 n/s/sr respectively. The development of a dedicated facility to produce kinematically focused neutrons is discussed.

Lebois, M.; Wilson, J. N.; Halipré, P.; Leniau, B.; Matea, I.; Oberstedt, A.; Oberstedt, S.; Verney, D.

2014-01-01

71

Testing inverse kinematic models of paleocrustal thickness in extensional systems with high-resolution forward thermo-mechanical models  

NASA Astrophysics Data System (ADS)

Reconstructing continental paleocrustal thickness is important for estimating tectonic accommodation, constraining three-dimensional basin geometry during early rifting phases of extensional margins and predicting the distribution of thick crustal sills that may block the global ocean and create restricted basins. We test an inverse kinematic method for modeling paleocrustal thickness by inverting the final bulk crustal structure produced from high-resolution thermo-mechanical models of lithospheric extension. The inverse kinematic method assumes pure shear, includes simple rules based on geodynamic models and field observations and requires displacement boundary conditions and the prescription of a transition from rigid to nonrigid deformation. The inverse pure-shear method produces a history of bulk crustal thickness that closely matches the forward models provided that the width of the rift zone is narrow during the later phases of continental extension when crust undergoes hyper-extension. We also observe that the width and surface trace of large-scale (LS) shear zones observed in the thermo-mechanical models coincide with inflection points and large gradients in inverted nonrigid velocity field. Our results demonstrate that if displacement boundary conditions can be constrained and the transition from rigid to nonrigid deformation defines a narrow rift zone during hyper-extension then relatively simple kinematic rules can be used to invert present-day bulk crustal structure for paleocrustal thickness, bulk lateral strain and aspects of upper crustal shear zone geometry from extensional systems with nonlinear rheology, structures dominated by simple shear in the upper crust, depth-dependent extension and asymmetric crustal thinning.

Kneller, Erik A.; Albertz, Markus; Karner, Garry D.; Johnson, Christopher A.

2013-07-01

72

Kinematic inversion of the 2008 Mw7 Iwate-Miyagi (Japan) earthquake by two independent methods: Sensitivity and resolution analysis  

NASA Astrophysics Data System (ADS)

On 14 June 2008, UTC 23:43, the border of Iwate and Miyagi prefectures was hit by an Mw7 reverse-fault type crustal earthquake. The event is known to have the largest ground acceleration observed to date (~4g), which was recorded at station IWTH25. We analyze observed strong motion data with the objective to image the event rupture process and the associated uncertainties. Two different slip inversion approaches are used, the difference between the two methods being only in the parameterization of the source model. To minimize mismodeling of the propagation effects we use crustal model obtained by full waveform inversion of aftershock records in the frequency range between 0.05-0.3 Hz. In the first method, based on linear formulation, the parameters are represented by samples of slip velocity functions along the (finely discretized) fault in a time window spanning the whole rupture duration. Such a source description is very general with no prior constraint on the nucleation point, rupture velocity, shape of the velocity function. Thus the inversion could resolve very general (unexpected) features of the rupture evolution, such as multiple rupturing, rupture-propagation reversals, etc. On the other hand, due to the relatively large number of model parameters, the inversion result is highly non-unique, with possibility of obtaining a biased solution. The second method is a non-linear global inversion technique, where each point on the fault can slip only once, following a prescribed functional form of the source time function. We invert simultaneously for peak slip velocity, slip angle, rise time and rupture time by allowing a given range of variability for each kinematic model parameter. For this reason, unlike to the linear inversion approach, the rupture process needs a smaller number of parameters to be retrieved, and is more constrained with a proper control on the allowed range of parameter values. In order to test the resolution and reliability of the retrieved models, we present a thorough analysis of the performance of the two inversion approaches. In fact, depending on the inversion strategy and the intrinsic 'non-uniqueness' of the inverse problem, the final slip maps and distribution of rupture onset times are generally different, sometimes even incompatible with each other. Great emphasis is devoted to the uncertainty estimate of both techniques. Thus we do not compare only the best fitting models, but their 'compatibility' in terms of the uncertainty limits.

Gallovic, Frantisek; Cirella, Antonella; Plicka, Vladimir; Piatanesi, Alessio

2013-04-01

73

Closed-form inverse kinematics for intra-operative mobile C-arm positioning with six degrees of freedom  

NASA Astrophysics Data System (ADS)

For trauma and orthopedic surgery, maneuvering a mobile C-arm X-ray device into a desired position in order to acquire the right picture is a routine task. The precision and ease of use of the C-arm positioning becomes even more important for more advanced imaging techniques as parallax-free X-ray image stitching, for example. Standard mobile C-arms have only five degrees of freedom (DOF), which definitely restricts their motions that have six DOF in 3D Cartesian space. We have proposed a method to model the kinematics of the mobile Carm and operating table as an integrated 6DOF C-arm X-ray imaging system.1 This enables mobile C-arms to be positioned relative to the patient's table with six DOF in 3D Cartesian space. Moving mobile C-arms to a desired position and orientation requires finding the necessary joint values, which is an inverse kinematics problem. In this paper, we present closed-form solutions, i.e. analytic expressions, obtained in an algebraic way for the inverse kinematics problem of the 6DOF C-arm model. In addition, we implement a 6DOF C-arm system for interactively radiation-free C-arm positioning based on a continuous guidance from C-arm pose estimation. For this we employ a visual marker pattern attached under the operating table and a mobile C-arm system augmented by a video camera and mirror construction. In our experiment, repositioning C-arm to a pre-defined pose in a phantom study demonstrates the practicality and accuracy of our developed 6DOF C-arm system.

Wang, Lejing; Zou, Rui; Weidert, Simon; Landes, Juergen; Euler, Ekkehard; Burschka, Darius; Navab, Nassir

2011-03-01

74

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

Microsoft Academic Search

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

Buqing Wang; Hanlin Chen; Shufeng Yang; Ancheng Xiao; Xiaogan Cheng; John A. Rupp

2005-01-01

75

Solving the differential biochemical Jacobian from metabolomics covariance data.  

PubMed

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

76

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

77

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

78

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

79

Neutron spectroscopic factors of Nickel-56 via Nickel(p,d)-56 Nickel-55 reaction in inverse kinematics  

NASA Astrophysics Data System (ADS)

Transfer reactions have been the classic tool for studying the angular distributions, the excitation energies, and the spectroscopic factors of possible single-particles states. With the advent of radioactive beams, there has been a renewed effort to utilize these beams in transfer reactions in inverse kinematics. The exact shell structure of the unstable doubly magic nucleus 56Ni has attracted a lot of interest recently. To test if 56Ni has a closed f7/2 orbital, we have carried out the 56Ni(p,d)55Ni transfer reaction measurement with the radioactive 56Ni beam in inverse kinematics for the first time at the NSCL using the HiRA array and S800 spectrograph. The spectroscopic factor predicted by the independent particle model is 8, shell-model calculations give value of 6.8. We have extracted spectroscopic factors of the 56Ni(p,d)55Ni reaction, for the ground and two excited states of 55Ni. The neutron SF value of 7 for the 56Ni(p,d)55Ni ground state agrees with shell-model calculations supports the view that 56Ni is a closed shell nucleus. This result supports the use of 56Ni as a core in shell-model calculations. Another important goal was to study the structure of 55Ni by determining the spin and parities of excited states. We have assigned an ? value of 1 to first excited state of 55Ni for 2.089 MeV state of 55Ni. We have extracted a spectroscopic factor of 0.14 for this state. This serves as a second test of the shell model, and the results agree with the shell model calculations. We have confirmed the tentative ? = 0 assumption for 3.185 MeV state. A neutron spectroscopic factor of 1.2 was obtained for this state.

Sanetullaev, Alisher

80

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

81

The effect of high-top and low-top shoes on ankle inversion kinematics and muscle activation in landing on a tilted surface  

PubMed Central

Background There is still uncertainty concerning the beneficial effects of shoe collar height for ankle sprain prevention and very few data are available in the literature regarding the effect of high-top and low-top shoes on muscle responses during landing. The purpose of this study was to quantify the effect of high-top and low-top shoes on ankle inversion kinematics and pre-landing EMG activation of ankle evertor muscles during landing on a tilted surface. Methods Thirteen physical education students landed on four types of surfaces wearing either high-top shoes (HS) or low-top shoes (LS). The four conditions were 15° inversion, 30° inversion, combined 25° inversion?+?10° plantar flexion, and combined 25° inversion?+?20° plantar flexion. Ankle inversion kinematics and EMG data of the tibialis anterior (TA), peroneus longus (PL), and peroneus brevis (PB) muscles were measured simultaneously. A 2?×?4 (shoe?×?surface) repeated measures ANOVA was performed to examine the effect of shoe and landing surfaces on ankle inversion and EMG responses. Results No significant differences were observed between the various types of shoes in the maximum ankle inversion angle, the ankle inversion range of motion, and the maximum ankle inversion angular velocity after foot contact for all conditions. However, the onset time of TA and PB muscles was significantly later wearing HS compared to LS for the 15° inversion condition. Meanwhile, the mean amplitude of the integrated EMG from the 50 ms prior to contact (aEMGpre) of TA was significantly lower with HS compared to LS for the 15° inversion condition and the combined 25° inversion?+?20° plantarflexion condition. Similarly, the aEMGpre when wearing HS compared to LS also showed a 37.2% decrease in PL and a 31.0% decrease in PB for the combined 25° inversion?+?20° plantarflexion condition and the 15° inversion condition, respectively. Conclusion These findings provide preliminary evidence suggesting that wearing high-top shoes can, in certain conditions, induce a delayed pre-activation timing and decreased amplitude of evertor muscle activity, and may therefore have a detrimental effect on establishing and maintaining functional ankle joint stability. PMID:24548559

2014-01-01

82

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

83

Kinematics and source zone properties of the 2004 Sumatra-Andaman earthquake and tsunami: Nonlinear joint inversion of tide gauge, satellite altimetry, and GPS data  

Microsoft Academic Search

We (re)analyzed the source of the 26 December 2004 Sumatra-Andaman earthquake and tsunami through a nonlinear joint inversion of an inhomogeneous data set made up of tide gauges, satellite altimetry, and far-field GPS recordings. The purpose is twofold: (1) the retrieval of the main kinematics rupture parameters (slip, rake, and rupture velocity) and (2) the inference of the rigidity of

S. Lorito; A. Piatanesi; V. Cannelli; F. Romano; D. Melini

2010-01-01

84

Using synthetic kinematic source inversions with dynamic rupture models to evaluate the effect of seismic network density and geometry in near-field source inversions  

NASA Astrophysics Data System (ADS)

Detailed source imaging of the spatial and temporal slip distribution of earthquakes is a main research goal for seismology. In this study we investigate how the number and geometrical distribution of seismic stations affect finite kinematic source inversion results by inverting ground motions derived from a known synthetic dynamic earthquake rupture model, which is governed by the slip weakening friction law with heterogeneous stress distribution. Our target dynamic rupture model is a buried strike-slip event (Mw 6.5) in a layered half space (Dalguer & Mai, 2011) with broadband synthetic ground motions created at 168 near-field stations. In the inversion, we modeled low frequency (under 1Hz) waveforms using a genetic algorithm in a Bayesian framework (Moneli et al. 2008) to retrieve peak slip velocity, rupture time, and rise time of the source. The dynamic consistent regularized Yoffe function (Tinti et al. 2005) was applied as a single window slip velocity function. Tikhonov regularization was used to smooth final slip. We tested three station network geometry cases: (a) single station, in which we inverted 3 component waveforms from a single station varying azimuth and epicentral distance; (b) multi-station configurations with similar numbers of stations all at similar distances from, but regularly spaced around the fault; (c) irregular multi-station configurations using different numbers of stations. For analysis, waveform misfits are calculated using all 168 stations. Our results show: 1) single station tests suggest that it may be possible to obtain a relatively good source model even using one station, with a waveform misfit comparable to that obtained with the best source model. The best single station performance occurs with stations in which amplitude ratios between the three components are not large, indicating that P & S waves are all present. We infer that both body wave radiation pattern and distance play an important role in selection of optimal station. 2) Multi-station tests indicate irregular distribution of stations with different azimuths and distances around the fault provides the best source models. The minimum waveform misfit is obtained using the all-168 stations, but source model is not significant improved by using denser network. It suggests the best source model is not necessarily derived from the model with minimum waveform misfit. 3) Number of stations affects the estimated source image, but a surprisingly small number of well-spaced stations appear sufficient to obtain acceptable solutions in our study. This study is done under unrealistic conditions, e.g. no noise on ground motions, fault geometry and velocity structure are perfectly known. However, we argue that it provides basic guidelines for seismic / GNSS network geometry for the study source models from real earthquakes. Also, this study suggests a-priori physical constraints for the earthquake source is required to exclude unrealistic models. A pseudo-dynamic source inversion, in which the correlation structures between source parameters inferred from dynamic rupture models (Song et al 2013, in review), will support such constraints, and is currently work in progress.

Zhang, Y.; Dalguer, L. A.; Song, S.; Clinton, J. F.

2013-12-01

85

Relationship of calculating the Jacobian matrices of nonlinear systems and population coding algorithms in neurobiology  

NASA Astrophysics Data System (ADS)

In this paper we examine how the calculation of Jacobian matrices in nonlinear systems is related to population coding algorithms in neurobiology. Population coding algorithms have been designed to retrodict sensory stimuli or predict motor behavior from neuronal responses. We simulate the visuomotor hand movement task of reaching in a plane. Adaptive feedback control updating of joint angles of a three-joint arm was used in the model. The control signal is the dot product between the visual error signal and the Jacobian matrix of the direct kinematic equation of hand movement. The x and y hand trajectories can follow the x and y time series of Lorenz and Ro¨ssler systems of coupled nonlinear equations. In this particular example, the elements of the Jacobian matrix can be estimated from observed changes in joint angles and Cartesian coordinate values of the hand. We also point out how the Jacobian matrices in nonlinear biological systems can be estimated in general from observed time series; e.g. joint angles, Cartesian coordinate values of hand movement, neural or muscle activity. Estimating Jacobian matrices of nonlinear functions from experimental observations can provide not only data analysis but also signal synthesis and can lead to a more realistic modeling of sensorimotor transformations.

G´l, Gyo¨ngyi

86

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

87

Kinematic inversion of Maule 2010, Chile and Tohoku 2011, Japan earthquakes using cGPS and Strong Motion data  

NASA Astrophysics Data System (ADS)

The Maule 2010 Mw 8.8 Chile and Tohoku 2011 Mw 9.0 earthquakes were recorded by continuous GPS (cGPS) and Strong Motion (SM) instruments, with good resolution at low and high frequencies, respectively. The dual behavior of low and high frequencies during large earthquakes is an important issue in seismic hazard because the highest seismic intensities are associated mainly with high frequency waves, while low frequency waves are associated with tsunami generation and the largest coseismic displacements. Previous works proposed that most of the low frequency waves were generated in the shallow part of the contact, while that high frequency waves were released in the deeper zone of the plate interface. We made kinematic inversions in different frequency bands using cGPS and SM to study the seismic ruptures and their frequency behavior. The AXITRA spectral code was used to simulate wave propagation in a flat layered medium. We used two approaches to model the source: elliptical patches and fixed rectangular mesh. Both models fit more than 90% of the variance. Our inversions for Tohoku earthquake show low frequency energy released in the shallow part of the interface and high frequency release in its deeper part, similar to findings in previous works. For Maule, on the other hand, we propose that the main high frequency source was located in the northern part of the rupture, not necessarily in the deeper contact zone that could not be broken during this earthquake. We think that high frequency is concentrated in the boundaries of the rupture caused by the arrest of the rupture propagation. The Maule rupture had a direction of propagation mainly from south to north generating a concentration of high frequency waves in small zones of the northern edge of the rupture. The Tohoku earthquake had a direction of propagation mainly from shallow depth to the deeper part of the plate interface generating more high frequency waves in small zones of the deeper edges. The Maule 2010 earthquake was recorded by several SM that previously recorded the Valparaiso 1985 Mw 8.0 earthquake. The Japanese strong motion networks have recorded several Mw ~ 8.0 earthquakes, like the Tokachi-oki 2003 earthquake. The comparison of SM of both mega-earthquakes with Mw ~ 8.0 earthquakes shows remarkable similarities: similar peak ground acceleration, peak ground velocity, duration of strong motion and high frequency spectrum. These similarities confirm our previous conclusions that high frequency are released by small zones where rupture is stopped by seismic barriers. Finally, the dual frequency behavior of seismic ruptures explains why at high frequencies the seismic intensities for mega-earthquakes are similar to those of Mw ~ 8.0 earthquakes and why for low frequency the seismic hazard of mega-earthquakes is higher generating larger tsunami propagation and coseismic displacements.

Ruiz, S.; Madariaga, R.

2012-04-01

88

Thick-target inverse-kinematics proton scattering from {sup 46}Ar and the N=28 shell below {sup 48}Ca  

SciTech Connect

Low-lying excited states of {sup 46}Ar have been studied via inverse-kinematics proton scattering with a thick target. Coupled-channels calculations have been used to extract the deformation length of the 2{sub 1}{sup +} state. This result, combined with existing Coulomb excitation data, yields a ratio of the neutron-to-proton transition matrix elements of M{sub n}/M{sub p}=1.19(25)N/Z, showing a departure from the proton dominance observed in the N=28 isotones above {sup 48}Ca. The status of the N=28 shell below {sup 48}Ca is discussed.

Riley, L.A.; Abdelqader, M.A.; Bojazi, M.J.; Spencer, T.P. [Department of Physics and Astronomy, Ursinus College, Collegeville, Pennsylvania 19426 (United States); Bazin, D.; Enders, J.; Gade, A.; Hu, Z.; Mueller, W.F. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Brown, B.A.; Campbell, C.M.; Church, J.A.; Dinca, D.-C.; Glasmacher, T.; Olliver, H.; Perry, B.C.; Sherrill, B.M.; Terry, J.R. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States); Cottle, P.D.; Kemper, K.W. [Department of Physics, Florida State University, Tallahassee, Florida 32306 (United States)] [and others

2005-08-01

89

Timing and Kinematics of Cretaceous to Paleogene inversion at the SE margin of the Central European Basin System: Part 1, Kinematics  

NASA Astrophysics Data System (ADS)

Late Cretaceous to Early Tertiary inversion of the Central European Basin system (CEBS) is remarkably heterogeneous in the mode and timing of structural inversion (i.e., including reactivation of normal faults). Paleogene inversion present in rifts from the British Isles to the Netherlands decreases eastward into the Lower Saxony basin. Further east, in the North East German basin (NEGB), the influence of Paleocene to Eocene events is difficult to prove. There, much or all of the inversion occurred in Late Cretaceous time. E.g., the Dekorp Basin 9601 regional seismic section shows flat lying Paleocene on top of steeply dipping, folded and thrust-faulted Triassic to Upper Cretaceous strata. Thickness variations of Lower Tertiary strata in the southern NEGB mostly result from differential subsidence by salt withdrawal: salt-cored anticlines subsided after Late Cretaceous inversion and formed up to 1400 m deep basins predominantly filled with Eocene to Oligocene sediments. Fission track dating on bedrock from the basement highs in central Germany supports the hypothesis of a short but intense phase of inversion in Late Cretaceous time, although some Early Tertiary exhumation is documented as well. Apart from the timing of inversion, the different parts of the CEBS differ in the magnitudes of uplift and horizontal shortening and in structural style. In the western and central parts of the basin system, Late Cretaceous shortening is focussed on the NW-SE trending Jurassic to Lower Cretaceous extensional basins. In contrast, little shortening is accommodated within the NEGB. Rather, it is concentrated in the Thüringer Wald, Harz and Flechtingen basement uplifts and associated footwall structures on the southern basin margin. There is no clear evidence for increased original thicknesses of the sedimentary cover overlying the basement uplifts. On the contrary, part of the area affected by basement thrusting was underlain by the Eichsfeld-Altmark swell, a long-lived paleogeographic and structural high of Permian-Jurassic age. There is also no evidence for the regional reverse faults being reactivated normal faults, so the basement thrusting does not represent inversion in a strict sense. Still further east in Poland, the magnitude of "true" basin inversion increases again in the Polish basin. Nevertheless, first results of structural balancing across the CEBS suggest that shortening and uplift attained a maximum on a transect crossing the East German basement uplifts. Bulk horizontal NE-SW shortening from Scandinavia to southern Germany is about 15-20 km there. The total shortening decreases westward to a few km on a southern North Sea transect and probably also toward the east, although regional uplift of the Bohemian Massif inducing widespread non-deposition or erosion of Mesozoic strata make this difficult to prove. The irregular arrangement of extensional basins and intervening highs or swells apparently had a stronger effect on shortening styles than magnitudes. A counterintuitive conclusion from the symmetric regional shortening pattern is that the basins were not mechanically weaker than some specific regions of unextended crust. Rather than particularly strong basins this probably indicates weak basin margins, potentially resulting from a thermal anomaly or a previously thickened felsic crust.

Jähne, F.; Kley, J.; Hoffmann, V. E.; Eynatten, H. V.; Dunkl, I.

2009-04-01

90

THE RIEMANN HYPOTHESIS FOR JACOBIAN ZETA FUNCTIONS ...  

E-print Network

May 15, 2013 ... Jacobian zeta functions are analogues of the Euler zeta function which ... function is said to be of Hermite class if it can be approximated ..... to a space H(E) whose defining function E(z) is a confluent hypergeometric series [1].

2013-05-15

91

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

92

Kinematic analysis of 7-DOF manipulators  

NASA Technical Reports Server (NTRS)

This article presents a kinematic analysis of seven-degree-of-freedom serial link spatial manipulators with revolute joints. To uniquely determine the joint angles for a given end-effector position and orientation, the redundancy is parameterized by a scalar variable that defines the angle between the arm plane and a reference plane. The forward kinematic mappings from joint space to end-effector coordinates and arm angle and the augmented Jacobian matrix that gives end-effector and arm angle rates as functions of joint rates are presented. Conditions under which the augmented Jacobian becomes singular are also given and are shown to correspond to the arm being either at a kinematically singular configuration or at a nonsingular configuration for which the arm angle ceases to parameterize the redundancy.

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

1992-01-01

93

Kinematic analysis of 7 DOF anthropomorphic arms  

NASA Technical Reports Server (NTRS)

A kinematic analysis of anthropomorphic seven-degree-of-freedom serial link spatial manipulators with revolute joints is presented. To uniquely determine joint angles for a given end-effector position and orientation, the redundancy is parameterized by a scalar variable which corresponds to the angle between the arm plane and a reference plane. The forward kinematic mappings from joint-space to end-effector coordinates and arm angle and the augmented Jacobian matrix which gives end-effector and arm angle rates as functions of joint rates are given. Conditions under which the augmented Jacobian becomes singular are given and are shown to correspond to the arm being either at a kinematically singular configuration or at a nonsingular configuration for which the arm angle ceases to parameterize the redundancy.

Kreutz-Delgado, K.; Long, M.; Seraji, H.

1990-01-01

94

Geometry and kinematics of the Main Himalayan Thrust and Neogene crustal exhumation in the Bhutanese Himalaya derived from inversion of multi-thermochronologic data  

NASA Astrophysics Data System (ADS)

Both climatic and tectonic processes affect bedrock erosion and exhumation in convergent orogens, but determining their respective influence is difficult. A requisite first step is to quantify long-term (~10 ^ 6 yr) erosion rates within an orogen. In the Himalaya, past studies suggest long-term erosion rates varied in space and time along the range front, resulting in numerous tectonic models to explain the observed erosion rate distribution. Here, we invert a large dataset of new and existing thermochronological ages to determine both long-term exhumation rates and the kinematics of Neogene tectonic activity in the eastern Himalaya in Bhutan. New data include 31 apatite and 5 zircon (U-Th)/He ages, and 49 apatite and 16 zircon fission-track ages along two North-South oriented transects across the orogen in western and eastern Bhutan. Data inversion was performed using a modified version of the 3-D thermo-kinematic model PECUBE, with parameter ranges defined by available geochronologic, metamorphic, structural and geophysical data. Among several important observations, our three main conclusions are: (1) Thermochronologic ages do not spatially correlate with surface traces of major fault zones, but appear to reflect the geometry of the underlying Main Himalayan Thrust; (2) our data are compatible with a strong tectonic influence, involving a variably dipping Main Himalayan Thrust geometry and steady-state topography; and (3) erosion rates have remained constant in western Bhutan over the last ~10 Ma, while a significant decrease occurred at ~6 Ma in eastern Bhutan, which we partially attribute to convergence partitioning into uplift of the Shillong plateau.

Coutand, Isabelle; Whipp, David, Jr.; Grujic, Djordje; Bernet, Matthias; Giuditta Fellin, Maria; Bookhagen, Bodo; Landry, Kyle; Ghalley, Kharka; Duncan, Chris

2014-05-01

95

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

96

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

97

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

98

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

99

Efficient noise tolerant reconstructions in diffuse optical tomography through computation of Jacobian in wavelet domain  

NASA Astrophysics Data System (ADS)

In this paper, we present a wavelet-based approach to solve the reconstruction problem encountered in diffuse optical tomography (DOT). The DOT reconstruction problem using model based iterative image reconstruction (MoBIIR) procedure involves repeated implementation of the three steps: (i) solution to the diffusion equation (DE) to generate the simulated data from the current optical properties, (ii) estimation of the Jacobian for the current optical property values and (iii) inversion of the perturbation equation leading to the update vectors for the optical properties. Consequently, there are three approaches to a wavelet based solution to the DOT problem: (i) waveletization of the perturbation equation, (ii) application of wavelets for computation of the Jacobian for use in the perturbation equation and (iii) the solution to the DE in the wavelet domain. While the first of these approaches has been addressed earlier, the other two have not been attempted to the best of our knowledge. In this work, we have attempted the second approach, i.e., waveletization of the perturbation equation for each measurement, which requires computing the Jacobian in the wavelet domain. Our results show that this method outperforms the earlier method. With each measurement appropriately represented in wavelet domain, the localization and de-noising property of wavelets are exploited. Our simulation results show that the mean-square-error at convergence is not affected by the increase in noise in data (up to 4% additive Gaussian noise). In addition, the usual V-cycle strategy of wavelets is attempted.

Kanmani, B.; Vasu, R. M.

2007-05-01

100

Predicting the drift motion for kinematically redundant robots  

Microsoft Academic Search

Redundant robots that are kinematically controlled by using Jacobian pseudoinverses may not have repeatable joint motions. This problem was initially observed and analyzed by C.A. Klein and C.H. Huang (1983). T. Shamir and Y. Yomdin (1988) analyzed this problem using a differential geometric approach. Both studies arrived at conditions under which a cyclic path in the work space does not

Shengwu Luo; Shaheen Ahmad

1992-01-01

101

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

102

Kinematic synthesis and analysis of a novel class of six-DOF parallel minimanipulators  

NASA Astrophysics Data System (ADS)

A new class of six degree of freedom (six-DOF) parallel minimanipulators is introduced. The minimanipulators are designed to provide high resolution and high stiffness in fine-manipulation operations. Two-DOF planar mechanisms (e.g., five-bar linkages, pantographs) and inextensible limbs are used to improve positional resolution and stiffness of the minimanipulators. The two-DOF mechanisms serve as drivers for the minimanipulators. The minimanipulators require only three inextensible limbs and, unlike most of the six-limbed parallel manipulators, their direct kinematics can be reduced to solving a polynomial in a single variable. All of the minimanipulator actuators are base-mounted. As a result, higher payload capacity, smaller actuator sizes, and lower power dissipation can be obtained. Inverse kinematics of the minimanipulators has been reduced to solving three decoupled quadratic equations, each of which contains only one unknown. Kinematic inversion is used to reduce the direct kinematics of the minimanipulator to an eighth-degree polynomial in the square of a single variable. Hence, the maximum number of assembly configurations for the minimanipulator is sixteen. It is proved that the sixteen solutions are eight pairs of reflected configurations with respect to the plane passing through the lower ends of the three limbs. The Jacobian and stiffness matrices of two types of minimanipulators are derived. It is shown that, at a central configuration, the stiffness matrix of the first type minimanipulator (driven by bidirectional linear stepper motors) can be decoupled, if proper design parameters are chosen. It is also shown that the stiffness of the minimanipulators is higher than that of the Stewart platform. Guidelines for obtaining large stiffness values and for designing the drivers of the second type minimanipulator (simplified five-bar linkages) are established. An algorithm is developed to determine the workspace of the minimanipulators. Given any orientation for the output link, three dimensional representation of the workspace is obtained. Guidelines for avoiding discontinuities inside of the workspace are established. inverse and direct kinematics singularities of the minimanipulators are obtained. &Guidelines for avoiding direct kinematics singularities, which occur within the minimanipulator workspace, are established.

Tahmasebi, Farhad

103

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

104

Kinematic analysis of the ARID manipulator  

NASA Technical Reports Server (NTRS)

The kinematic structure of the ARID manipulator lends itself to simple forward and inverse kinematics analysis. The purpose of this paper is to fully document and verify an existing analysis. The symbolic software package MATHEMATICA was used to produce and verify the equations presented here. In the analysis to follow, the standard Devenit-Hartenberg kinematic parameters of the ARID were employed.

Doty, Keith L

1992-01-01

105

Multi-GPU Jacobian accelerated computing for soft-field tomography.  

PubMed

Image reconstruction in soft-field tomography is based on an inverse problem formulation, where a forward model is fitted to the data. In medical applications, where the anatomy presents complex shapes, it is common to use finite element models (FEMs) to represent the volume of interest and solve a partial differential equation that models the physics of the system. Over the last decade, there has been a shifting interest from 2D modeling to 3D modeling, as the underlying physics of most problems are 3D. Although the increased computational power of modern computers allows working with much larger FEM models, the computational time required to reconstruct 3D images on a fine 3D FEM model can be significant, on the order of hours. For example, in electrical impedance tomography (EIT) applications using a dense 3D FEM mesh with half a million elements, a single reconstruction iteration takes approximately 15-20 min with optimized routines running on a modern multi-core PC. It is desirable to accelerate image reconstruction to enable researchers to more easily and rapidly explore data and reconstruction parameters. Furthermore, providing high-speed reconstructions is essential for some promising clinical application of EIT. For 3D problems, 70% of the computing time is spent building the Jacobian matrix, and 25% of the time in forward solving. In this work, we focus on accelerating the Jacobian computation by using single and multiple GPUs. First, we discuss an optimized implementation on a modern multi-core PC architecture and show how computing time is bounded by the CPU-to-memory bandwidth; this factor limits the rate at which data can be fetched by the CPU. Gains associated with the use of multiple CPU cores are minimal, since data operands cannot be fetched fast enough to saturate the processing power of even a single CPU core. GPUs have much faster memory bandwidths compared to CPUs and better parallelism. We are able to obtain acceleration factors of 20 times on a single NVIDIA S1070 GPU, and of 50 times on four GPUs, bringing the Jacobian computing time for a fine 3D mesh from 12 min to 14 s. We regard this as an important step toward gaining interactive reconstruction times in 3D imaging, particularly when coupled in the future with acceleration of the forward problem. While we demonstrate results for EIT, these results apply to any soft-field imaging modality where the Jacobian matrix is computed with the adjoint method. PMID:23010857

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

2012-10-01

106

Force-free Jacobian equilibria for Vlasov-Maxwell plasmas  

SciTech Connect

New analytic force-free Vlasov-Maxwell equilibria for thin current sheets are presented. The magnetic flux densities are expressed in terms of Jacobian elliptic functions of one Cartesian spatial coordinate. The magnetic flux densities reduce to previously reported hyperbolic functions in one limit and sinusoidal functions in another limit of the modulus k. A much wider class of nonlinear force-free Vlasov-Maxwell equilibria open expanded possibilities for modeling of solar system, astrophysical and laboratory plasmas. Modified Maxwellian distribution functions are determined explicitly in terms of Jacobian elliptic functions. Conditions for double peaked distribution functions that could be unstable are developed.

Abraham-Shrauner, B. [Department of Electrical and Systems Engineering, Washington University, St. Louis, Missouri 63130 (United States)] [Department of Electrical and Systems Engineering, Washington University, St. Louis, Missouri 63130 (United States)

2013-10-15

107

Brief paper Modified transpose Jacobian control of robotic systems  

Microsoft Academic Search

The simplicity of Transpose Jacobian (TJ) control is a significant characteristic of this algorithm for controlling robotic manipulators. Nevertheless, a poor performance may result in tracking of fast trajectories, since it is not dynamics-based. Use of high gains can deteriorate performance seriously in the presence of feedback measurement noise. Another drawback is that there is no prescribed method of selecting

S. Ali; A. Moosavian; Evangelos Papadopoulos

108

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

109

Kinematic Analysis of a Macro-Micro Redundantly Actuated Parallel Manipulator  

Microsoft Academic Search

In this paper the kinematic and Jacobian analysis of a macro–micro parallel manipulator is studied in detail. The manipulator architecture is a simplified planar version adopted from the structure of the Large Adaptive Reflector (LAR), the Canadian design of the next generation of giant radio telescopes. This structure is composed of two parallel and redundantly actuated manipulators at the macro

Hamid D. Taghirad; Meyer Nahon

2008-01-01

110

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

E-print Network

to serial manipulators, parallel manipulators can admit not only multiple inverse kinematic solutions, which makes it possible to separate the inverse kinematic solutions. The aim of this paper is to show with the existence of multiple inverse kinematic solutions in serial manipulators, the notion of aspects

Paris-Sud XI, Université de

111

Exploration of Three-Body Decay using Jacobian Coordinates  

NASA Astrophysics Data System (ADS)

Experiments on neutron-rich nuclei may result in the emission of one or more neutrons. Attempting to find a clear signature of two-neutron decay is possible in some systems, but more difficult in others. The goal in a two-neutron analysis is improving the algorithm for biasing toward true two-neutron events while removing one-neutron scatter. A continuing challenge is to find a better method to do this task. A contaminant beam of 32Mg produced isotopes of 30Na and 29Na with possible two-neutron coincidences during an experiment using the Sweeper-MoNA facility at the National Superconducting Cyclotron Laboratory (NSCL), located at Michigan State University. We analyzed these two isotopes by using Jacobian coordinate systems and comparing to typical gates that the research collaboration has used previously. The exploration of physical parameters to Jacobian coordinates will be presented.

Hoffmann, Mark; Williams, Kyle; Frank, Nathan

2012-10-01

112

Jacobian variety and integrable system — after Mumford, Beauville and Vanhaecke  

NASA Astrophysics Data System (ADS)

Beauville [A. Beauville, Jacobiennes des courbes spectrales et systèmes hamiltoniens complètement intégrables, Acta. Math. 164 (1990) 211-235] introduced an integrable Hamiltonian system whose general level set is isomorphic to the complement of the theta divisor in the Jacobian of the spectral curve. This can be regarded as a generalization of the Mumford system [D. Mumford, Tata Lectures on Theta II, Birkhäuser, 1984]. In this article, we construct a variant of Beauville's system whose general level set is isomorphic to the complement of the intersection of the translations of the theta divisor in the Jacobian. A suitable subsystem of our system can be regarded as a generalization of the even Mumford system introduced by Vanhaecke [P. Vanhaecke, Linearising two-dimensional integrable systems and the construction of action-angle variables, Math. Z. 211 (1992) 265-313; P. Vanhaecke, Integrable systems in the realm of algebraic geometry, in: Lecture Notes in Mathematics, vol. 1638, 2001].

Inoue, Rei; Konishi, Yukiko; Yamazaki, Takao

2007-02-01

113

Nilpotent Jacobians E.M.G.M. Hubbers  

E-print Network

1970 te Nijmegen #12; Promotor: Prof. dr. A.H.M. Levelt Copromotor: Dr. A.R.P. van den EssenNilpotent Jacobians E.­M.G.M. Hubbers F := 0 B B B B B B @ -x 1 -x 2 -x 3 . . . -xn 1 C C C C C C, Oakland) Prof. dr. D. Wright (Washington University, St. Louis) Copyright c # 1998 E.­M.G.M. Hubbers

Hubbers, Engelbert

114

Real-time estimate of body kinematics during a planar squat task using a single inertial measurement unit.  

PubMed

This study aimed at the real-time estimation of the lower-limb joint and torso kinematics during a squat exercise, performed in the sagittal plane, using a single inertial measurement unit placed on the lower back. The human body was modeled with a 3-DOF planar chain. The planar IMU orientation and vertical displacement were estimated using one angular velocity and two acceleration components and a weighted Fourier linear combiner. The ankle, knee, and hip joint angles were thereafter obtained through a novel inverse kinematic module based on the use of a Jacobian pseudoinverse matrix and null-space decoupling. The aforementioned algorithms were validated on a humanoid robot for which the mechanical model used and the measured joint angles virtually exhibited no inaccuracies. Joint angles were estimated with a maximal error of 1.5°. The performance of the proposed analytical and experimental methodology was also assessed by conducting an experiment on human volunteers and by comparing the relevant results with those obtained through the more conventional photogrammetric approach. The joint angles provided by the two methods displayed differences equal to 3±1°. These results, associated with the real-time capability of the method, open the door to future field applications in both rehabilitation and sport. PMID:23392337

Bonnet, Vincent; Mazzà, Claudia; Fraisse, Philippe; Cappozzo, Aurelio

2013-07-01

115

A comparison of the Gauss–Newton and quasi-Newton methods in resistivity imaging inversion  

Microsoft Academic Search

The smoothness-constrained least-squares method is widely used for two-dimensional (2D) and three-dimensional (3D) inversion of apparent resistivity data sets. The Gauss–Newton method that recalculates the Jacobian matrix of partial derivatives for all iterations is commonly used to solve the least-squares equation. The quasi-Newton method has also been used to reduce the computer time. In this method, the Jacobian matrix for

M. H. Loke; T. Dahlin

2002-01-01

116

Exploring strange nonchaotic attractors through Jacobian elliptic functions  

NASA Astrophysics Data System (ADS)

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 quasiperiodically forced systems. We found similar scenarios of SNAs from the analysis of two representative examples: a quasiperiodically forced damped pendulum and a two-dimensional map. This clearly well-suited and advantageous use of the JEFs, which in their own right lie at the heart of nonlinear physics, may encourage students at intermediate university levels to study them in depth.

Martínez García-Hoz, A.; Chacón, R.

2011-11-01

117

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

118

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.

2014-03-10

119

On-line estimation of image jacobian matrix by improved Broyden's method in uncalibrated visual servoing  

NASA Astrophysics Data System (ADS)

A novel improved broyden's method has been presented to estimate image jacobian matrix for uncalibrated visual servoing. In this paper, we apply chebyshev polynomial as a cost function to approximate best value. Compared with recursive least square (RLS) algorithm which is restricted by the prior knowledge for obtaining some performances, chebyshev polynomial algorithm has a great adaptability to estimate jacobian parameter, even without the prior knowledge. A microscopic image jacobian model has been developed for the four degree-of-freedom micromanipulator in our microassembly system. The performance has been confirmed by simulations and experiments.

Zeng, Xiangjin; Huang, Xinhan; Wang, Min

2007-11-01

120

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

121

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

122

Strategies for visco-acoustic waveform inversion: Parameter resolution, preconditioning and regularization  

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. Simultaneous inversion of velocity and attenuation tend to cause significant ';cross-talk' between the resulting images, reflecting a lack of parameter resolution and indicating the need for pre-conditioning and regularization of the inverse problem.We analyse the cross-talk issue by partitioning the inversion parameters into two classes; the velocity parameter class, and the attenuation parameter class. Both parameters are defined at a reference frequency, and a dispersion relation is assumed that describes these parameters at any other frequency. We formulate the model gradient of the objective function at a forward modelling frequency, and convert them to the reference frequency by employing the Jacobian of the coordinate change represented by the dispersion relation. At a given modelling frequency, the Frechet derivatives corresponding to these two parameter classes differ only by a 90 degree phase shift, meaning that the magnitudes of resulting model updates will be unscaled, and will not reflect the expected magnitudes in realistic (Q>>1) media. Due to the lack of scaling, cross-talk will be enhanced by poor subsurface illumination, by errors in kinematics, and by data noise. Initial results from a suite of synthetic cross-hole tests using a three-layer randomly heterogenous model with both intrinsic and extrinsic (scattering) attenuation demonstrate that cross-talk is a significant problem in attenuation inversion. Using the same model, we further show that cross-talk can be suppressed by varying the attenuation scaling term in our pre-conditioning operator. This strategy is effective for simultaneous inversion of velocity and attenuation, and for sequential inversion (a two-stage approach in which only the velocity models are recovered in the first stage). Further regularization using a smoothing term applied to the attenuation parameters is also effective in reducing cross-talk, which is often highly oscillatory. The sequential inversion approach restricts the search space for attenuation parameters, and appears to be helpful in retrieving a reliable attenuation model.

Kamei, R.; Pratt, R. G.

2013-12-01

123

On the generation of atmospheric property Jacobians from the (V)LIDORT linearized radiative transfer models  

NASA Astrophysics Data System (ADS)

The linearized radiative transfer models VLIDORT and LIDORT will deliver profile weighting functions (Jacobians) with respect to layer optical properties. We derive transformation rules for the conversion of layer Jacobian output to weighting functions defined for level (layer boundary) quantities such as volume mixing ratio, temperature and pressure. In a related development, we discuss the derivation of bulk-property atmospheric Jacobians with respect to quantities such as the temperature shift, the surface pressure and scaling parameters for constituent profiles. We also present some rules for calculating Jacobians for parameters characterizing aerosol loading regimes. An appendix contains linearization (with respect to temperature and pressure) of the trace species cross-sections derived from the HITRAN line spectroscopy data base.

Spurr, Robert; Christi, Matt

2014-07-01

124

Kinematic fault slip model from joint inversion of teleseismic, GPS, InSAR and subpixel-correlation measurements of the 2010 El Mayor-Cucapah earthquake and postseismic deformation (Invited)  

NASA Astrophysics Data System (ADS)

We use interferometric analysis of synthetic aperture radar (SAR) images (InSAR) and pixel tracking by subpixel correlation of SAR and optical images to map the fault ruptures and surface deformation of the 4 April 2010 El Mayor-Cucapah earthquake (Mw 7.2) in Baja California, Mexico. We then combine sampled InSAR and subpixel correlation results with GPS offsets at PBO stations and teleseismic waveforms in a joint inversion to produce a kinematic fault slip model. Pixel-tracking measurements from SPOT 2.5 m panchromatic images and from Envisat ASAR and ALOS PALSAR images measure large ground displacements close to fault ruptures, with a strong discontinuity where the rupture reached the surface. Optical image subpixel correlation measures horizontal displacements in both the east-west and north-south directions and shows the earthquake ruptured the Pescadores Fault in the southern Sierra Cucapah and the Borrego Fault in the central and northern edge of the mountain range. At the south end of the Sierra Cucapah, the fault ruptures fork into two subparallel strands with substantial slip on both visible. SAR image subpixel correlation measures horizontal deformation in the along-track direction of the satellite (approximately north or south) and in the radar line-of-sight direction. SAR along-track offsets, especially on ALOS images, show that there is a large amount of right-lateral slip (1-3 m) on a previously unmapped system of faults extending about 60 km to the southeast of the epicenter beneath the Colorado River Delta named the Indiviso Fault system. Aftershocks also extend approximately the same distance to the southeast. InSAR analyses of Envisat, ALOS and UAVSAR images, measure the surface displacements in the same radar line-of-sight as the range pixel tracking, but with much greater precision. Combination of SAR images from different directions allows the separation of the vertical and east components of the deformation, revealing the large normal fault slip in the Sierra Cucapah (down to the east) and blocks with substantial vertical motion in the Delta (both down to the east and down to the west). Kinematic finite fault modeling shows a bilateral rupture with fault slip shallower than 10 km on the faults to the NW and SE of the epicenter. The InSAR also reveals slip on many minor faults on both sides of the Sierra Cucapah and to the northwest, with displacements of cm to 10’s of cm. High-resolution UAVSAR coseismic and postseismic interferograms revealed triggered slip on a number of faults in the Yuha desert and Salton Trough, with some slip occurring in the three months after the main shock. Postseismic InSAR shows rapid afterslip on shallow faults at the north and south ends of the main coseismic rupture. Areas of the Colorado River Delta that subsided during the main earthquake continued to subside afterwards. Larger spatial scales of postseismic deformation that would be expected from viscoelastic relaxation are difficult to measure in the InSAR data because of large variations in tropospheric water vapor.

Fielding, E. J.; Wei, S.; Leprince, S.; Sladen, A.; Simons, M.; Avouac, J.; Briggs, R. W.; Hudnut, K. W.; Helmberger, D. V.; Hensley, S.; Hauksson, E.; Gonzalez-Garcia, J. J.; Herring, T.; Akciz, S. O.

2010-12-01

125

Kinematic Coseismic Slip Model for the 12 May 2008 Wenchuan-Beichuan Mw 7.9 Earthquake in Sichuan, China from Joint Inversion of ALOS, Envisat and Teleseismic Data*  

NASA Astrophysics Data System (ADS)

The Mw 7.9 earthquake struck Sichuan province on 12 May 2008 causing catastrophic damage over a large area including the county seats of Wenchuan and Beichuan. We use pixel-offset analysis of amplitude images for ALOS PALSAR and Envisat ASAR coseismic pairs to map the major surface ruptures. The largest amount of displacement (2--8 m of oblique right-lateral slip) occurred along the Beichuan fault and an extension to the north for a total distance of about 215 km. A second major rupture occurred on the Hanwang fault (a section of the Pengguan fault), beneath an anticline in the Sichuan basin about 10 km to the SE of the Beichuan fault, with nearly pure thrust slip. A third short, but intense, rupture strikes NW through the town of Xiaoyudong and transfers slip to another thrust about 5 km SE of the main rupture that ruptured only about 6 km parallel to the Beichuan fault. This small, probably shallow, block moved at least 5 m in the ALOS line of sight. Kinematic slip models for the earthquake have been estimated using a joint inversion of teleseismic data with the six ascending-track PALSAR and three descending-track ASAR strip-map interferograms. The models show that the rupture initiated with a small, 3-second pulse of emergent displacement followed by 15 seconds of moderate moment release with nearly pure thrust motion. More rapid moment release then started about 20 km from the hypocenter at shallower depths near the SW end of the major surface ruptures on the Beichuan fault. Another major patch of slip, coherent with the pixel-offset and InSAR analysis, is identified 130 km away from the epicenter, near the town of Beichuan. While the southern part of the rupture had primarily thrust motion, slip rotated to right-lateral as the rupture propagated the NE. *Part of this research was performed at the Jet Propulsion Laboratory, California Institute of Technology under contract with the National Aeronautics and Space Administration.

Fielding, E. J.; Sladen, A.; Li, Z.; Ryder, I.; Bürgmann, R.; Avouac, J.

2008-12-01

126

Study of the Jacobian of an Extended Kalman Filter for soil analysis in SURFEXv5  

NASA Astrophysics Data System (ADS)

An externalised surface scheme like SURFEX allows computationally cheap offline runs. This is a major advantage for surface assimilation techniques such as the Extended Kalman Filter (EKF), where the offline runs allow a cheaper numerical estimation of the observation operator Jacobian. In the recent past an EKF has been developped within SURFEX for the initialisation of soil water content and soil temperature based on screen-level temperature and relative humidity observations. In this paper we make a comparison of the Jacobian calculated with offline SURFEX runs and with runs coupled to the atmospheric ALARO model. Comparisons are made with respect to spatial structure and average value of the Jacobian, gain values and increments. We determine the optimal perturbation size of the Jacobian for the offline and coupled approaches and compare the linearity of the Jacobian for these cases. Results show that the offline Jacobian approach gives similar results as the coupled approach and it allows for smaller perturbation sizes that better approximate this linearity assumption. We document a new case of non-linearities that can hamper this linearity assumption and cause spurious 2?t oscillations in small parts of the domain for the coupled as well as the offline runs. While these oscillations do not have a detrimental effect on the model run, they can introduce some noise in the Jacobian in the affected locations. The oscillations influence both the surface fluxes and the screen-level variables. The oscillations occur in the late afternoon in summer when a stable boundary layer starts to form near the surface. We propose a filter to remove the oscillations and show that this filter works accordingly.

Duerinckx, A.; Hamdi, R.; Mahfouf, J.-F.; Termonia, P.

2014-10-01

127

Kinematic resection  

NASA Astrophysics Data System (ADS)

A new geometric formulation is given for the problem of determining position and orientation of a satellite scanner from error-prone ground control point observations in linear pushbroom imagery. The pushbroom satellite resection problem is significantly more complicated than that of the conventional frame camera because of irregular platform motion throughout the image capture period. Enough ephemeris data are typically available to reconstruct satellite trajectory and hence the interior orientation of the pushbroom imagery. The new approach to resection relies on the use of reconstructed scanner interior orientation to determine the relative orientations of a bundle of image rays. The absolute position and orientation which allows this bundle to minimize its distance from a corresponding set of ground control points may then be found. The interior orientation is represented as a kinematic chain of screw motions, implemented as dual-number quaternions. The motor algebra is used in the analysis since it provides a means of line, point, and motion manipulation. Its moment operator provides a metric of distance between the image ray and the ground control point.

Shevlin, Fergal P.

1995-01-01

128

Symbolic Kinematics and Dynamics Analysis and Control of a General  

E-print Network

Symbolic Kinematics and Dynamics Analysis and Control of a General Stewart Parallel Manipulator these advantages, the kinematic and dynamic analyses are extremely complicated. Such models are important in terms of qualitative analysis of the required actuator forces to realize certain end-effector task (inverse dynamics

Krovi, Venkat

129

Neural network Jacobian analysis for high-resolution profiling of the atmosphere  

NASA Astrophysics Data System (ADS)

Neural networks have been widely used to provide retrievals of geophysical parameters from spectral radiance measurements made remotely by air-, ground-, and space-based sensors. The advantages of retrievals based on neural networks include speed of execution, simplicity of the trained algorithm, and ease of error analysis, and the proliferation of high quality training data sets derived from models and/or operational measurements has further facilitated their use. In this article, we provide examples of geophysical retrieval algorithms based on neural networks with a focus on Jacobian analysis. We examine a hypothetical 80-channel hyperspectral microwave atmospheric sounder (HyMAS) and construct examples comparing neural network water vapor retrieval performance with simple regressions. Jacobians (derivatives of the outputs with respect to the network weights and with respect to the inputs) are also presented and discussed. Finally, a discussion of the Jacobian operating points is provided.

Blackwell, William J.

2012-12-01

130

Principal Component Geostatistical Approach for large-dimensional inverse problems  

NASA Astrophysics Data System (ADS)

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

131

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.

Kitanidis, P K; Lee, J

2014-01-01

132

Model inversion by parameter fit using NN emulating the forward model: evaluation of indirect measurements.  

PubMed

The usage of inverse models to derive parameters of interest from measurements is widespread in science and technology. The operational usage of many inverse models became feasible just by emulation of the inverse model via a neural net (NN). This paper shows how NNs can be used to improve inversion accuracy by minimizing the sum of error squares. The procedure is very fast as it takes advantage of the Jacobian which is a byproduct of the NN calculation. An example from remote sensing is shown. It is also possible to take into account a non-diagonal covariance matrix of the measurement to derive the covariance matrix of the retrieved parameters. PMID:17521878

Schiller, Helmut

2007-05-01

133

Flux Jacobian matrices and generaled Roe average for an equilibrium real gas  

NASA Technical Reports Server (NTRS)

Inviscid flux Jacobian matrices and their properties used in numerical solutions of conservation laws are extended to general, equilibrium gas laws. Exact and approximate generalizations of the Roe average are presented. Results are given for one-dimensional flow, and then extended to three-dimensional flow with time-varying grids.

Vinokur, Marcel

1988-01-01

134

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

135

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. Plumpton, M. John D. Hayes, Robert G. Langlois and Bruce V. Burlton Department of Mechanical and Aerospace. Atlas is a six degree of freedom vehicle op- erating training simulator motion platform where orienting

Hayes, John

136

A Unified Microwave Radiative Transfer Model with Jacobian for General Stratified Media  

NASA Astrophysics Data System (ADS)

A unified microwave radiative transfer (UMRT) model is developed for rapid, stable and accurate level-centric calculation of the thermal radiation emitted from any geophysical medium comprised of planar layers of either densely or tenuously distributed, moderately sized spherical scatterers. The formulation includes rapid calculation of the tangent linear relationship (i.e., Jacobian) between the observed brightness temperature and any relevant radiative and geophysical layer parameters, such as the scattering and absorption coefficients, temperature, temperature lapse rate, and medium layer thickness. UMRT employs a rapid multistream scattering-based discrete ordinate eigenanalysis solution with a layer-adding algorithm stabilized by incorporating symmetrization of the discretized differential radiative transfer equations and analytical diagonalization and factorization of the resulting symmetric and positive definite matrices. It is based on the discrete ordinate tangent linear radiative transfer model of Voronovich et al. (2004), but extended to include both Mie and dense media scattering theories and employ refractive layers. Other nontrivial extensions are: 1) exact modeling of linearized temperature profiles and resulting radiation streams across medium layers, 2) compensation for refracted radiation streams using Snell's law, the Fresnel reflectivity and transmissivity coefficients, and a cubic spline interpolation matrix, and 3) seamless calculation of associated Jacobians for both sparse and dense medium parameters. Details of the UMRT Jacobian formulation are presented. The entire formulation has been programmed in Matlab and validated through both energy conservation and numerical Jacobian intercomparisons. Comparisons of the upwelling brightness temperatures over dry snow and ice from simulations and field measurements are presented and discussed.

Tian, Miao

137

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

138

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

139

Inverse Functions  

NSDL National Science Digital Library

Using Mathcad, Maple, Mathmatica, or MatLab, learner should be able to review concepts of inverse functions, and to use those concepts, together with functions defined by integrals, to develop inverse trigonometric functions.

Smith, David; Moore, Lawrence

2001-01-25

140

Kinematic Analysis of a Serial Parallel Machine Tool: the VERNE machine Daniel Kanaan, Philippe Wenger and Damien Chablat  

E-print Network

1 Kinematic Analysis of a Serial ­ Parallel Machine Tool: the VERNE machine Daniel Kanaan, Philippe machine tool: the VERNE machine. This machine is composed of a three-degree-of-freedom (DOF) parallel machines; Machine tool; Complex motion; Inverse kinematics; Forward kinematics. 1. Introduction Parallel

Paris-Sud XI, Université de

141

ADIFOR working note {number_sign}2: Using ADIFOR to compute dense and sparse Jacobians  

SciTech Connect

ADIFOR is a source translator that, given a collection of Fortran subroutines for the computation of a ``function,`` produces Fortran code for the computation of the derivatives of this function. More specifically, ADIFOR produces code to compute the matrix-matrix product JS, where J is the Jacobian of the ``function`` with respect to the user-defined independent variables, and S is the composition of the derivative objects corresponding to the independent variables. This interface is flexible; by setting S = x, one can compute the matrix-vector product Jx, or by setting S = I, one can compute the whole Jacobian J. Other initializations of S allow one to exploit a known sparsity structure of J. This paper illustrates the proper initialization of ADIFOR-generated derivative codes and the exploitation of a known structure of J.

Bischof, C.; Hovland, P.

1992-01-01

142

ADIFOR working note. number sign. 2: Using ADIFOR to compute dense and sparse Jacobians  

SciTech Connect

ADIFOR is a source translator that, given a collection of Fortran subroutines for the computation of a function,'' produces Fortran code for the computation of the derivatives of this function. More specifically, ADIFOR produces code to compute the matrix-matrix product JS, where J is the Jacobian of the function'' with respect to the user-defined independent variables, and S is the composition of the derivative objects corresponding to the independent variables. This interface is flexible; by setting S = x, one can compute the matrix-vector product Jx, or by setting S = I, one can compute the whole Jacobian J. Other initializations of S allow one to exploit a known sparsity structure of J. This paper illustrates the proper initialization of ADIFOR-generated derivative codes and the exploitation of a known structure of J.

Bischof, C.; Hovland, P.

1992-01-01

143

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

144

Kinematic Analysis of the vertebra of an eel like robot  

E-print Network

The kinematic analysis of a spherical wrist with parallel architecture is the object of this article. This study is part of a larger French project, which aims to design and to build an eel like robot to imitate the eel swimming. To implement direct and inverse kinematics on the control law of the prototype, we need to evaluate the workspace without any collisions between the different bodies. The tilt and torsion parameters are used to represent the workspace.

Chablat, Damien

2008-01-01

145

Introducing the Jacobian-volume-histogram of deforming organs: application to parotid shrinkage evaluation  

NASA Astrophysics Data System (ADS)

The Jacobian of the deformation field of elastic registration between images taken during radiotherapy is a measure of inter-fraction local deformation. The histogram of the Jacobian values (Jac) within an organ was introduced (JVH—Jacobian-volume-histogram) and first applied in quantifying parotid shrinkage. MVCTs of 32 patients previously treated with helical tomotherapy for head-neck cancers were collected. Parotid deformation was evaluated through elastic registration between MVCTs taken at the first and last fractions. Jac was calculated for each voxel of all parotids, and integral JVHs were calculated for each parotid; the correlation between the JVH and the planning dose-volume histogram (DVH) was investigated. On average, 82% (±17%) of the voxels shrinks (Jac < 1) and 14% (±17%) shows a local compression >50% (Jac < 0.5). The best correlation between the DVH and the JVH was found between V10 and V15, and Jac < 0.4-0.6 (p < 0.01). The best constraint predicting a higher number of largely compressing voxels (Jac0.5<7.5%, median value) was V15 >= 75% (OR: 7.6, p = 0.002). Jac and the JVH are promising tools for scoring/modelling toxicity and for evaluating organ/contour variations with potential applications in adaptive radiotherapy.

Fiorino, Claudio; Maggiulli, Eleonora; Broggi, Sara; Liberini, Simone; Mauro Cattaneo, Giovanni; Dell'Oca, Italo; Faggiano, Elena; Di Muzio, Nadia; Calandrino, Riccardo; Rizzo, Giovanna

2011-06-01

146

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

147

Humanoid Walking Robot: Modeling, Inverse Dynamics, and Gain Scheduling Control  

E-print Network

trajectories, recorded from real human walking cycle data. Kinematic and dynamic analysis is discussed, including the model kinematics, dynamics and controls, with numerical solution simulations for desired joint1 Humanoid Walking Robot: Modeling, Inverse Dynamics, and Gain Scheduling Control Elvedin Kljuno

Williams II, Robert L.

148

Compactness vs. Smoothness: Methods for regularizing fault slip inversions with application to subduction zone earthquakes  

Microsoft Academic Search

We examine inversions of geodetic data for fault slip and discuss how inferred results are affected by choices of regularization. The final goal of any slip inversion is to enhance our understanding of the dynamics governing fault zone processes through kinematic descriptions of fault zone behavior at various temporal and spatial scales. Important kinematic observations include ascertaining whether fault slip

R. B. Lohman; M. Simons

2004-01-01

149

A unified method for the formation of all planar jointed kinematic chains and Baranov trusses  

Microsoft Academic Search

A schema is presented which contains all the independent varieties of planar jointed kinematic chains and Baranov trusses. The schema requires four operations: amplification with dyads, simplification of the joints, graphisation, and inverse graphisation.

N I Manolescu

1979-01-01

150

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

151

Assessing the quality of curvilinear coordinate meshes by decomposing the Jacobian matrix  

NASA Technical Reports Server (NTRS)

An algebraic decomposition of the Jacobian matrix which relates physical and computational variables is presented. This invertible decomposition parameterizes the mesh by the physically intuitive qualities of cell orientation, cell orthogonality, cell volume, and cell aspect ratio. The decomposition can be used to analyze numerically generated curvilinear coordinate meshes and to assess the contribution of the mesh to the truncation error for any specific differential operator and algorithm. This is worked out in detail for Laplace's equation in nonconservative and conservative forms. The analysis is applied to the solution of the full potential code TAIR, showing grid plots, carpet plots, and truncation error for a NACA 0012 airfoil.

Kerlick, G. D.; Klopfer, G. H.

1982-01-01

152

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

153

The application of the dual number methods to scara kinematics  

Microsoft Academic Search

The screw theory has been an extraordinary important mathematical tool in research of spatial mechanics, also the dual number methods can describe the screw motion of rigid body wonderfully. By introducing the basic conceptions of dual number methods, the link dual matrix comprising the D-H parameters is constituted, furthermore, the direct and inverse kinematics of the SCARA robot was solved.

Yang Jin; Wang Xiaorong

2010-01-01

154

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

155

A modal approach to hyper-redundant manipulator kinematics  

SciTech Connect

This paper presents novel and efficient kinematic modeling techniques for hyper-redundant'' robots. This approach is based on a backbone curve'' that captures the robot's macroscopic geometric features. The inverse kinematic, or hyper-redundancy resolution,'' problem reduces to determining the time varying backbone curve behavior. To efficiently solve the inverse kinematics problem, the authors introduce a modal'' approach, in which a set of intrinsic backbone curve shape functions are restricted to a modal form. The singularities of the modal approach, modal non-degeneracy conditions, and modal switching are considered. For discretely segmented morphologies, the authors introduce fitting'' algorithms that determine the actuator displacements that cause the discrete manipulator to adhere to the backbone curve. These techniques are demonstrated with planar and spatial mechanism examples. They have also been implemented on a 30 degree-of-freedom robot prototype.

Chirikjian, G.S. (Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Mechanical Engineering); Burdick, J.W. (California Inst. of Tech., Pasadena, CA (United States). School of Engineering and Applied Science)

1994-06-01

156

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

157

Inverse Psoriasis  

MedlinePLUS

... lesions in the skin folds. People with severe inverse psoriasis may occasionally require UVB (ultraviolet B) light therapy or biologic medications to control the condition. Get Social National Psoriasis Foundation Our ...

158

Jacobian-free Newton-Krylov methods with GPU acceleration for computing nonlinear ship wave patterns  

E-print Network

The nonlinear problem of steady free-surface flow past a submerged source is considered as a case study for three-dimensional ship wave problems. Of particular interest is the distinctive wedge-shaped wave pattern that forms on the surface of the fluid. By reformulating the governing equations with a standard boundary-integral method, we derive a system of nonlinear algebraic equations that enforce a singular integro-differential equation at each midpoint on a two-dimensional mesh. Our contribution is to solve the system of equations with a Jacobian-free Newton-Krylov method together with a banded preconditioner that is carefully constructed with entries taken from the Jacobian of the linearised problem. Further, we are able to utilise graphics processing unit acceleration to significantly increase the grid refinement and decrease the run-time of our solutions in comparison to schemes that are presently employed in the literature. Our approach provides opportunities to explore the nonlinear features of three-...

Pethiyagoda, Ravindra; Moroney, Timothy J; Back, Julian M

2014-01-01

159

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

160

Coupled fractional nonlinear differential equations and exact Jacobian elliptic solutions for exciton-phonon dynamics  

NASA Astrophysics Data System (ADS)

An improved quantum model for exciton-phonon dynamics in an ?-helix is investigated taking into account the interspine coupling and the influence of power-law long-range exciton-exciton interactions. Having constructed the model Hamiltonian, we derive the lattice equations and employ the Fourier transforms to go in continuum space showing that the long-range interactions (LRI) lead to a nonlocal integral term in the equations of motion. Indeed, the non-locality originating from the LRI results in the dynamic equations with space derivatives of fractional order. New theoretical frameworks are derived, such that: fractional generalization of coupled Zakharov equations, coupled nonlinear fractional Schrödinger equations, coupled fractional Ginzburg-Landau equations, coupled Hilbert-Zakharov equations, coupled nonlinear Hilbert-Ginzburg-Landau equations, coupled nonlinear Schrödinger equations and coupled nonlinear Hilbert-Schrödinger equations. Through the F-expansion method, we derive a set of exact Jacobian solutions of coupled nonlinear Schrödinger equations. These solutions include Jacobian periodic solutions as well as bright and dark soliton which are important in the process of energy transport in the molecule. We also discuss of the impact of LRI on the energy transport in the molecule.

Mvogo, Alain; Ben-Bolie, G. H.; Kofané, T. C.

2014-07-01

161

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

162

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

163

Qualitative Kinematics in Mechanisms  

Microsoft Academic Search

This paper investigates the problem of reasoning about the kinematic interactions between parts of a mechanism We introduce the concept of Place Vocabularies as a useful symbolic description of the possible interactions We examine the requirements for the representation and introduce a definition of place vocabularies that satisfies them We show how this representation can be computed from metric data

Boi Faltings

1987-01-01

164

PD plus error-dependent integral nonlinear controllers for robot manipulators with an uncertain Jacobian matrix.  

PubMed

In framework of traditional PID controllers, there are only three parameters available to tune, as a result, performance of the resulting system is always limited. As for Cartesian regulation of robot manipulators with uncertain Jacobian matrix, a scheme of PID controllers with error-dependent integral action is proposed. Compare with traditional PID controllers, the error-dependent integration is employed in the proposed PID controller, in which more parameters are available to be tuned. It provides additional flexibility for controller characteristics and tuning as well, and hence makes better transient performance. In addition, asymptotic stability of the resulting closed-loop system is guaranteed. All signals in the system are bounded when exogenous disturbances and measurement noises are bounded. Numerical example demonstrates the superior transient performance of the proposed controller over the traditional one via Cartesian space set-point manipulation of two-link robotic manipulator. PMID:22818429

Huang, C Q; Xie, L F; Liu, Y L

2012-11-01

165

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

166

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

167

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

168

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

169

Kinematics of robot manipulators  

SciTech Connect

The theory and methodology of design of general-purpose machines that may be controlled by a computer to perform all the tasks of a set of special-purpose machines is the focus of modern machine design research. These seventeen contributions chronicle recent activity in the analysis and design of robot manipulators that are the prototype of these general-purpose machines. They focus particularly on kinematics, the geometry of rigid-body motion, which is an integral part of machine design theory. The challenges to kinematics researchers presented by general-purpose machines such as the manipulator are leading to new perspectives in the design and control of simpler machines with two, three, and more degrees of freedom. Researchers are rethinking the uses of gear trains, planar mechanisms, adjustable mechanisms, and computer controlled actuators in the design of modern machines.

McCarthy, J.M.

1986-01-01

170

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

171

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

172

Robot coordinate transformations and their Jacobians This is a two link robot, with a shoulder angle and an elbow angle . The upper arm  

E-print Network

is the Jacobian in this state? Answer: (; 1p2 ;1) ;1 1p2 0 ! (5) (b) Let the robot wave a little, from the elbow it as a matrix equation. Answer: yes it is, even though it depends non-linearly on and . The matrix form of eq.(3 of freedom of motion. How do you expect the Jacobian to change? (10) Purely mathematically, the degeneracy

Dorst, Leo

173

Shot-put kinematics  

NASA Astrophysics Data System (ADS)

The problem of the optimum throw in the shot-put discipline is analysed by relaxing the assumption that the height H, from which the athlete releases the shot, does not depend on the angle ? which the arm of the putter makes with the horizontal axis. In this context, the kinematics of the shot-put is studied and results are compared with the traditional analysis, which considers the height H, the angle ? and the modulus V0 of the initial velocity of the metal sphere as independent parameters.

DeLuca, R.

2005-11-01

174

A Jacobian-free Newton Krylov method for mortar-discretized thermomechanical contact problems  

NASA Astrophysics Data System (ADS)

Multibody contact problems are common within the field of multiphysics simulation. Applications involving thermomechanical contact scenarios are also quite prevalent. Such problems can be challenging to solve due to the likelihood of thermal expansion affecting contact geometry which, in turn, can change the thermal behavior of the components being analyzed. This paper explores a simple model of a light water reactor nuclear fuel rod, which consists of cylindrical pellets of uranium dioxide (UO 2) fuel sealed within a Zircalloy cladding tube. The tube is initially filled with helium gas, which fills the gap between the pellets and cladding tube. The accurate modeling of heat transfer across the gap between fuel pellets and the protective cladding is essential to understanding fuel performance, including cladding stress and behavior under irradiated conditions, which are factors that affect the lifetime of the fuel. The thermomechanical contact approach developed here is based on the mortar finite element method, where Lagrange multipliers are used to enforce weak continuity constraints at participating interfaces. In this formulation, the heat equation couples to linear mechanics through a thermal expansion term. Lagrange multipliers are used to formulate the continuity constraints for both heat flux and interface traction at contact interfaces. The resulting system of nonlinear algebraic equations are cast in residual form for solution of the transient problem. A Jacobian-free Newton Krylov method is used to provide for fully-coupled solution of the coupled thermal contact and heat equations.

Hansen, Glen

2011-07-01

175

Inverse Functions  

NSDL National Science Digital Library

In this activity students use log tapes and base-two slide rules as references to graph exponential functions and log functions in base-10 and base-2. Students discover that exponential and log functions are inverse, reflecting across the y = x axis as mirror images. This is activity E2 in the "Far Out Math" educator's guide. Lessons in the guide include activities in which students measure, compare quantities as orders of magnitude, become familiar with scientific notation, and develop an understanding of exponents and logarithms using examples from NASA's GLAST mission. These are skills needed to understand the very large and very small quantities characteristic of astronomical observations. Note: In 2008, the GLAST mission was renamed Fermi, for the physicist Enrico Fermi.

176

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

177

Control Engineering Practice 14 (2006) 11231124 Book review  

E-print Network

of Jacobian using the examples of three-link planar arm and Stanford Manipulator. The sections on kinematic Kinemantics three major topics of rotations & homogeneous transformations, forward kinematics, and inverse kinematics are all brought together in a single chapter. This is a sensible saving as compared to other

Pota, Himanshu Roy

178

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

179

Kinematics of coastal deformation  

NASA Astrophysics Data System (ADS)

Relating the distributed strain and often complicated styles of faulting in deforming continental lithosphere to relative motion of the oceanic plates has proven difficult. A new method to study the kinematics of continental deformation in Asia has been used by A. J. Haines and W. E. Holt, Geology and Geophysics Division, Department of Scientific and Industrial Research, Wellington, New Zealand.Moment tensor elements from large and moderate-sized earthquakes in Asia over the last 85 years [Molnar and Deng, 1984; Molnar and Lyon-Caen, 1989; Ekstrom and England, 1989; W. E. Holt et al., unpublished manuscript, 1990] have been used to determine strain rates, relative velocities, and relative rotations within the deforming regions of Eastern Tibet, Western Sichuan, and Yunnan. That is, velocities and rotations within a deforming zone can be uniquely determined in a given reference frame if the strains are known everywhere within that zone [Haines, 1982

Haines, A. J.; Holt, W. E.

180

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

181

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

182

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

183

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

184

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

185

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

186

Kinetics of hula hooping: An inverse dynamics analysis  

Microsoft Academic Search

This paper involved a biomechanical analysis of lower limb joint coordination during hula hooping. A lower extremity inverse dynamics model that incorporated kinematic input and force platform data was developed to compute the angular velocities, moments about and powers produced at the lower extremity joints. The abductor moments and powers were discovered to be paramount in maintaining hoop oscillations, as

T. Cluff; D. G. E. Robertson; R. Balasubramaniam

2008-01-01

187

Inverse dynamic analysis of parallel manipulators with full mobility  

Microsoft Academic Search

An approach is presented for automatically generating inverse dynamic solutions for planar parallel manipulators with 3-DOF and spatial parallel manipulators with 6-DOF, thereby eliminating the errors and tedium associated with hand derivations. Kinematic and dynamic equations are formulated using a combination of linear graph theory, the principle of virtual work, and symbolic programming. A planar RRR manipulator and a Gough–Stewart

Thomas Geike; John McPhee

2003-01-01

188

An Accurate Method of Computing the Gradient of Seismic Wave Reflection Coefficients (SWRCs) for the Inversion of Stratum Parameters  

NASA Astrophysics Data System (ADS)

The optimization inversion method based on derivatives is an important inversion technique in seismic data processing, where the key problem is how to compute the Jacobian matrix. The computational precision of the Jacobian matrix directly influences the success of the optimization inversion method. Currently, most of the AVO (amplitude versus offset) inversions are based on approximate expressions for the Zoeppritz equations to obtain the derivatives of the seismic wave reflection coefficients (SWRCs) with respect to the stratum parameters. As a result, the computational precision and range of applications of these AVO inversions are restricted undesirably. In order to improve the computational precision and to extend the range of applications of AVO inversions, the partial derivative equations of the Zoeppritz equations are established, with respect to the ratios of wave velocities and medium densities. By solving the partial derivative equations of the Zoeppritz equations accurately, we obtained the partial derivative of SWRCs with respect to the ratios of seismic wave velocities and medium densities. With the help of the chain rule for derivatives, the gradient of the SWRCs can be accurately computed. To better understand the behavior of the gradient of the SWRCs, we plotted the partial derivative curves of the SWRCs, analyzed the characteristics of these curves, and gained some new insight into the derivatives. Because only a linear system of equations is solved in our method without adding any new restrictions, the new computational method has both high precision and a quick running speed; it is not only suitable for small incident angles and weak reflection seismic waves but also for large incident angles and strong reflection seismic waves. With the theoretical foundations established in the article, we can further study inversion problems for layered stratum structures and we can further improve the computational speed and precision of the inversions.

Liu, Xiao-Bo; Liu, Fu-Ping; Meng, Xian-Jun; Xiao, Jia-Qi

2012-03-01

189

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

190

Kinematic precision of gear trains  

NASA Technical Reports Server (NTRS)

Kinematic precision is affected by errors which are the result of either intentional adjustments or accidental defects in manufacturing and assembly of gear trains. A method for the determination of kinematic precision of gear trains is described. The method is based on the exact kinematic relations for the contact point motions of the gear tooth surfaces under the influence of errors. An approximate method is also explained. Example applications of the general approximate methods are demonstrated for gear trains consisting of involute (spur and helical) gears, circular arc (Wildhaber-Novikov) gears, and spiral bevel gears. Gear noise measurements from a helicopter transmission are presented and discussed with relation to the kinematic precision theory.

Litvin, F. L.; Goldrich, R. N.; Coy, J. J.; Zaretsky, E. V.

1982-01-01

191

Generation of planar kinematic chains  

Microsoft Academic Search

This work presents a completely automated, mathematically rigorous procedure that generates all planar, non-fractionated, pin-jointed kinematic chains having 2–6 independent loops and 1, 2, or 3 degrees of freedom. It also addresses the isomorphism problem and the elimination of rigid subchains. The computer programs can be run on any personal computer (XT or higher); over 6 million kinematic chains and

E. R Tuttle

1996-01-01

192

Optimisation of Automotive Seat Kinematics  

Microsoft Academic Search

\\u000a Automotive seating structures have evolved over an extended period of development, resulting in convergence of practical embodiments\\u000a to a planar kinematic chain, typically based on a four-bar linkage. Seating structures are subject to a stringent set of constraints\\u000a and objectives, including: allowable envelope of motion, structural integrity, modularity and product cost. Although four-bar\\u000a linkage kinematics is well understood, the large

M. Leary; M. Mazur; T. Mild; A. Subic

193

DEPLOYABLE ANTENNA KINEMATICS USING TENSEGRITY STRUCTURE DESIGN  

E-print Network

DEPLOYABLE ANTENNA KINEMATICS USING TENSEGRITY STRUCTURE DESIGN By BYRON FRANKLIN KNIGHT .........................................................................................................5 Tensegrity Overview

Florida, University of

194

Solving coupled groundwater flow systems using a Jacobian Free Newton Krylov method  

NASA Astrophysics Data System (ADS)

Jacobian Free Newton Kyrlov (JFNK) methods can have several advantages for simulating coupled groundwater flow processes versus conventional methods. Conventional methods are defined here as those based on an iterative coupling (rather than a direct coupling) and/or that use Picard iteration rather than Newton iteration. In an iterative coupling, the systems are solved separately, coupling information is updated and exchanged between the systems, and the systems are re-solved, etc., until convergence is achieved. Trusted simulators, such as Modflow, are based on these conventional methods of coupling and work well in many cases. An advantage of the JFNK method is that it only requires calculation of the residual vector of the system of equations and thus can make use of existing simulators regardless of how the equations are formulated. This opens the possibility of coupling different process models via augmentation of a residual vector by each separate process, which often requires substantially fewer changes to the existing source code than if the processes were directly coupled. However, appropriate perturbation sizes need to be determined for accurate approximations of the Frechet derivative, which is not always straightforward. Furthermore, preconditioning is necessary for reasonable convergence of the linear solution required at each Kyrlov iteration. Existing preconditioners can be used and applied separately to each process which maximizes use of existing code and robust preconditioners. In this work, iteratively coupled parent-child local grid refinement models of groundwater flow and groundwater flow models with nonlinear exchanges to streams are used to demonstrate the utility of the JFNK approach for Modflow models. Use of incomplete Cholesky preconditioners with various levels of fill are examined on a suite of nonlinear and linear models to analyze the effect of the preconditioner. Comparisons of convergence and computer simulation time are made using conventional iteratively coupled methods and those based on Picard iteration to those formulated with JFNK to gain insights on the types of nonlinearities and system features that make one approach advantageous. Results indicate that nonlinearities associated with stream/aquifer exchanges are more problematic than those resulting from unconfined flow.

Mehl, S.

2012-12-01

195

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

196

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

197

Kinematic Control of Redundant Manipulators: Generalizing the Task-Priority Framework to Inequality Task  

Microsoft Academic Search

Redundant mechanical systems like humanoid robots are de- signed to fulfill multiple tasks at a time. A task, in velocity-resolved inverse kinematics, is a desired value for a function of the robot configuration that can be regulated with an ordinary differential equation (ODE). When facing simultaneous tasks, the corresponding equations can be grouped in a single system or, better, sorted

Oussama Kanoun; Florent Lamiraux; Pierre-Brice Wieber

2011-01-01

198

A dual neural network for kinematic control of redundant robot manipulators  

Microsoft Academic Search

The inverse kinematics problem in robotics can be formulated as a time-varying quadratic optimization problem. A new recurrent neural network, called the dual network, is presented in this paper. The proposed neural network is composed of a single layer of neurons, and the number of neurons is equal to the dimensionality of the workspace. The proposed dual network is proven

Youshen Xia; Jun Wang

2001-01-01

199

Kinematic, static and dynamic analysis of a planar 2DOF tensegrity mechanism  

Microsoft Academic Search

Tensegrity mechanisms are lightweight, deployable and can be accurately modeled. Consequently, they constitute an interesting alternative to conventional mechanisms for some applications. In this work, the kinematics, statics and dynamics of a planar two-degree-of-freedom tensegrity mechanism are studied. Solutions to the direct and inverse static problems are first presented. Afterwards, the boundaries of the actuator and Cartesian workspaces of the

Marc Arsenault; Clément M. Gosselin

2006-01-01

200

Deformation field validation and inversion applied to adaptive radiation therapy  

NASA Astrophysics Data System (ADS)

Development and implementation of chronological and anti-chronological adaptive dose accumulation strategies in adaptive intensity-modulated radiation therapy (IMRT) for head-and-neck cancer. An algorithm based on Newton iterations was implemented to efficiently compute inverse deformation fields (DFs). Four verification steps were performed to ensure a valid dose propagation: intra-cell folding detection finds zero or negative Jacobian determinants in the input DF; inter-cell folding detection is implemented on the resolution of the output DF; a region growing algorithm detects undefined values in the output DF; DF domains can be composed and displayed on the CT data. In 2011, one patient with nonmetastatic head and neck cancer selected from a three phase adaptive DPBN study was used to illustrate the algorithms implemented for adaptive chronological and anti-chronological dose accumulation. The patient received three 18F-FDG-PET/CTs prior to each treatment phase and one CT after finalizing treatment. Contour propagation and DF generation between two consecutive CTs was performed in Atlas-based autosegmentation (ABAS). Deformable image registration based dose accumulations were performed on CT1 and CT4. Dose propagation was done using combinations of DFs or their inversions. We have implemented a chronological and anti-chronological dose accumulation algorithm based on DF inversion. Algorithms were designed and implemented to detect cell folding.

Vercauteren, Tom; De Gersem, Werner; Olteanu, Luiza A. M.; Madani, Indira; Duprez, Fréderic; Berwouts, Dieter; Speleers, Bruno; De Neve, Wilfried

2013-08-01

201

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

202

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

203

Robust pre-stack seismic waveform inversion for acoustic, elastic isotropic and anisotropic media parameters  

NASA Astrophysics Data System (ADS)

Seismic prestack waveform inversion is an ill posed, nonlinear inverse problem with nonunique solutions. Additionally the problem suffers from the existence of multiple local optima in the topography of the data misfit measure and high computational cost. These problems get aggravated as the number of model parameters to be estimated per layer or grid point increase. The number of parameters per layer or grid point depends on the assumptions necessary for modeling the seismic data. Hence it is necessary to investigate the physical processes affecting the observed data significantly in specific situations and then develop appropriate inversion methodologies. In this dissertation I apply a local inversion scheme based on nonlinear least squares (NLS) approach to invert one dimensional synthetic and one and two dimensional field seismic prestack waveform data in an area with sparse direct measurements to estimate sound speed in the oceanic water column. This is because seismic propagation is acoustic and isotropic in water and density does not change significantly. The two dimensional results are further compared to that obtained using a completely global approach. I also develop an adjoint state method based Jacobian computation for the NLS scheme to be applied to the problem of acoustic seismic inversion. Next, I investigate and propose an efficient method to monitor CO2 sequestrated reservoirs by combining multiphase flow simulation results with seismic modeling. Finding that such a monitoring scheme would require multicomponent seismic waveform data inversion under elastic anisotropic assumptions, I cast the inverse problem as a multiobjective optimization problem and solve it using a nondominated sorting genetic algorithm. Synthetic and real data tests show that while local inversion schemes work reasonably well for acoustic inversion, elastic anisotropic inversion requires a global approach utilizing multicomponent data. Hence monitoring CO2 sequestrated reservoirs efficiently using proxy stack of anisotropic layers requires the second approach. I also show that the NLS approach can be made efficient using the adjoint state method if the number of model parameters to be estimated is large enough. In the other case, computing the Jacobian using the traditional method and parallelization is preferable and can be implemented easily.

Padhi, Amit

204

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

205

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

206

Kinematics of ulnar head arthroplasty.  

PubMed

This in vitro study evaluated the performance of an ulnar head replacement. A joint simulator was employed that produced active forearm rotation in cadaveric specimens, with motion measured using an electromagnetic tracking system. The kinematics of the intact forearm were compared with a partial ulnar head replacement and a full replacement (with and without soft-tissue reconstruction) and a full excision of the ulnar head. There were no differences between intact kinematics and those following prosthetic reconstruction. However, ulnar head excision produced distal radioulnar joint instability in the form of radioulnar convergence and increased anteroposterior translations. PMID:14599827

Gordon, K D; Dunning, C E; Johnson, J A; King, G J W

2003-12-01

207

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

208

Kinematic sensitivity of robot manipulators  

NASA Technical Reports Server (NTRS)

Kinematic sensitivity vectors and matrices for open-loop, n degrees-of-freedom manipulators are derived. First-order sensitivity vectors are defined as partial derivatives of the manipulator's position and orientation with respect to its geometrical parameters. The four-parameter kinematic model is considered, as well as the five-parameter model in case of nominally parallel joint axes. Sensitivity vectors are expressed in terms of coordinate axes of manipulator frames. Second-order sensitivity vectors, the partial derivatives of first-order sensitivity vectors, are also considered. It is shown that second-order sensitivity vectors can be expressed as vector products of the first-order sensitivity vectors.

Vuskovic, Marko I.

1989-01-01

209

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

210

Sparse matrix inverse factors  

SciTech Connect

The inverses of matrix factors lend themselves to parallel operations in the direct solution phase of sparse matrix solutions. These inverse factors, given suitable ordering of the equations, are themselves sparse, if less so than the original factors. Partitioning reduces the build-up of nonzero elements in the inverse factors. All of the multiplications required for repeat solutions may be performed in parallel using the inverse factors, with only as many serial steps as twice the number of factors.

Enns, M.K. (Electrocon International, Inc., Ann Arbor, MI (USA)); Tinney, W.F.; Alvarado, F.L. (Wisconsin Univ., Madison, WI (USA))

1990-05-01

211

Joint inversion for thermal and petrophysical properties from wireline and temperature observations  

NASA Astrophysics Data System (ADS)

High resolution temperature logs are extremely useful in geothermal studies but the analysis of their detailed structure requires good control on the thermal properties of the subsurface. This is often achieved by a two step procedure where first thermal conductivity is derived from well logging data and then used to infer the heat flux density of the temperature log. Here, an algorithm is presented that incorporates both steps into a single inversion procedure. In addition to the petrophysical inverse problem and steady-state heat conduction, transient temperature signals, e.g., originating from past surface temperature change, are included. Computational requirements differ from conventional algorithms for the petrophysical problem because the differential equation for transient heat conduction needs to be solved numerically, resulting in a more complex forward problem. The inverse problem is solved by a Quasi-Newton iterative scheme, allowing for a Bayesian approach as well as a Tikhonov type regularization. The Jacobian matrix may be calculated either by traditional finite-differences, or by using automatic differentiation. The technique of matrix compression is considered to achieve a most efficient implementation. Matrix compression can drastically improve the computational speed for calculating the Jacobian for certain classes of problems. Those involving transient heat conduction cannot be compressed efficiently whereas purely petrophysical problems have a much higher compression ratio. Results of the algorithm are verified by using well-known programs for paleoclimate and petrophysical inversion. A borehole in Southern Germany serves as a case study for the algorithm. The algorithm is able to match both wireline and temperature data with good accuracy and in a consistent manner. The ground surface temperature history of the last glacial cannot be reconstructed without ambiguity because the log terminates too shallow for a full reconstruction. An important result is the correlation between the transient temperature perturbation and the shale petrophysical properties which are usually not well-known but may play an important role when transient problems in sedimentary rocks are considered.

Hartmann, Andreas; Rath, Volker

2010-05-01

212

Inverse Campaigning &ast  

Microsoft Academic Search

It can be advantageous for an ‘office motivated’ party A to spend effort to make it public that a group of voters will lose from party A's policy proposal. Such effort is called inverse campaigning. The inverse campaigning equilibria are described for the case where the two parties can simultaneously reveal information publicly to uninformed voters. Inverse campaigning dissipates the

Kai A. Konrad; FÜR SOZIALFORSCHUNG

2004-01-01

213

Geophysical InversionFacility  

E-print Network

UBC Geophysical InversionFacility Modelling and Inversion of EMI data collected over magnetic soils of EMI data acquired at sites with magnetic soils · Geophysical Proveouts · Geonics EM63 Data · First model parameters: · Location · Orientation · Polarizabilities 4 #12;UBC Geophysical Inversion Facility

Oldenburg, Douglas W.

214

Kinematic solution of spherical Stephenson-III six-bar mechanism  

NASA Astrophysics Data System (ADS)

A closed-form solution can be obtained for kinematic analysis of spatial mechanisms by using analytical method. However, extra solutions would occur when solving the constraint equations of mechanism kinematics unless the constraint equations are established with a proper method and the solving approach is appropriate. In order to obtain a kinematic solution of the spherical Stephenson-III six-bar mechanism, spherical analytical theory is employed to construct the constraint equations. Firstly, the mechanism is divided into a four-bar loop and a two-bar unit. On the basis of the decomposition, vectors of the mechanism nodes are derived according to spherical analytical theory and the principle of coordinate transformation. Secondly, the structural constraint equations are constructed by applying cosine formula of spherical triangles to the top platform of the mechanism. Thirdly, the constraint equations are solved by using Bezout’s elimination method for forward analysis and Sylvester’s resultant elimination method for inverse kinematics respectively. By the aid of computer symbolic systems, Mathematica and Maple, symbolic closed-form solution of forward and inverse displacement analysis of spherical Stephenson-III six-bar mechanism are obtained. Finally, numerical examples of forward and inverse analysis are presented to illustrate the proposed approach. The results indicate that the constraint equations established with the proposed method are much simpler than those reported by previous literature, and can be readily eliminated and solved.

Liu, Yanfang; Yang, Suixian

2013-09-01

215

First order ball bearing kinematics  

NASA Technical Reports Server (NTRS)

Two first order equations are given connecting geometry and internal motions in an angular contact ball bearing. Total speed, kinematic equivalence, basic speed ratio, and modal speed ratio are defined and discussed; charts are given for the speed ratios covering all bearings and all rotational modes. Instances where specific first order assumptions might fail are discussed, and the resulting effects on bearing performance reviewed.

Kingbury, E.

1984-01-01

216

Kinematic support using elastic elements  

NASA Technical Reports Server (NTRS)

The design of kinematic supports using elastic elements is reviewed. The two standard methods (cone, Vee and flat and three Vees) are presented and a design example involving a machine tool metrology bench is given. Design goals included thousandfold strain attenuation in the bench relative to the base when the base strains due to temperature variations and shifting loads. Space applications are also considered.

Geirsson, Arni; Debra, Daniel B.

1988-01-01

217

The kinematics of multi-fingered manipulation  

Microsoft Academic Search

In this paper, we derive a configuration-space description of the kinematics of the fingers-plus-object system. To do this, we first formulate contact kinematics as a “virtual” kinematic chain. Then, the system can be viewed as one large closed kinematic chain composed of smaller chains, one for each finger and one for each contact point. We examine the underlying configuration space

David J. Montana

1995-01-01

218

Dynamics and Kinematics Simulation for Robots  

Microsoft Academic Search

The objective of this research is to design and develop the dynamics and kinematics simulation software for robot education purpose. The dynamic models of robots and controllers are composed of, six types of robot and PID-controller. The kinematics model to consider Forward kinematics based on Denavit-Hartenberg Transformation. MATLAB software is applied for creating graphical user interface allowing users to choose

S. Fueanggan; S. Chokchaitam

2009-01-01

219

The Kinematic Theory of Solar Dynamo  

Microsoft Academic Search

Generation of the Sun's magnetic fields by self-inductive processes in the solar electrically conducting interior, the solar dynamo theory, is a fundamentally important subject in astrophysics. The kinematic dynamo theory concerns how the magnetic fields are produced by kinematically possible flows without being constrained by the dynamic equation. We review a number of basic aspects of the kinematic dynamo theory,

Ke-Ke Zhang; Xin-Hao Liao

2003-01-01

220

EGRM 201 Dynamics and Kinematics (3 Credits)  

E-print Network

and Energy - Chapter 14 30-Sep T 5-Oct R Impulse and Momentum - Chapter 15 7-Oct T 12-Oct R Planar KinematicsEGRM 201 ­ Dynamics and Kinematics (3 Credits) COURSE POLICY- FALL 2004 Instructor ­ Karla Mossi 7-Sep R Kinematics of a Particle - Chapter 12 9-Sep T September 10th -NOTIFY OF RELIGIOUS HOLIDAYS

Mossi, Karla

221

The Isoconditioning Loci of A Class of Closed-Chain Manipulators  

Microsoft Academic Search

The subject of this paper is a special class of closed-chain manipulators. First, we analyze a family of two-degree-of-freedom (dof) five-bar planar linkages. Two Jacobian matrices appear in the kinematic relations between the joint-rate and the Cartesian-velocity vectors, which are called the ``inverse kinematics\\

Damien Chablat; Philippe Wenger; Jorge Angeles

2007-01-01

222

Analysis of solution lineations in pebbles: Kinematical vs. dynamical approaches  

NASA Astrophysics Data System (ADS)

Solution lineations in conglomerates, resulting from indentation of non-soluble grains of the matrix into the surface of soluble pebbles, make up a morphological and genetic continuum with gradual transition between orthogonal stylolites, oblique slickolites and parallel striations. The distributions of incidence angles of matrix grains have been analyzed in individual pebbles in order to discern their kinematical or dynamical meaning. As a general rule, they fit theoretical models of flow trajectories determined by the bulk strain ( kinematical hypothesis). In contrast, they are not consistent with dynamical hypotheses based upon relationships with stress vectors. In particular, they do not fit the model of frictional sliding, which would give rise to a sharp discontinuity between slickolites parallel to the maximum principal stress ?1 and true striations parallel to the resolved shear stress ?. Therefore, solution lineations all around a pebble cannot be considered as an analogue of multiple fault slip data, and they should not be generally analysed by methods of stress inversion based upon Bott's principle. Under certain conditions (high pebble solubility; active pressure-solution processes able to accommodate the strain rate; earlier cementation), the solution lineations tend to be parallel to each other and to the maximum shortening/compression axis. They therefore assume a double kinematical and dynanical meaning, and the deformation involves maximum volume reduction.

Simón, José L.

2007-12-01

223

Kinematic and stability motion limits for a hexapod walking machine  

NASA Astrophysics Data System (ADS)

The major problem addressed by this research is to investigate and implement the basic concepts necessary to lay the groundwork for efficient forms of motion planning, motion control, and gait algorithms with respect to hexapod walking machines. Specifically, the approach taken was to develop and implement the concepts of a stability margin and a joint space motion margin on an object-oriented representation of the Aquarobot. The model was generated in Franz Common Lisp and simulated via Allegro Common Windows. A method by which distance computations can be calculated and applied to the center of mass and triangular support pattern of a walking machine to determine the stability margin is introduced. Inverse kinematics and joint limits are utilized to ascertain the joint space motion margin of the model. Response to impending instability and the effect when a joint hits or approaches a joint kinematic limit on the motion of the hexapod walking machine by stopping the model is also addressed. The results are as follows: the concepts of the joint space motion margin and the stability margin can be successfully implemented on a kinematic model and graphical simulation of a hexapod walking machine. These concepts contribute to future work in the area of more efficient free gait algorithms, specifically asynchronous gait algorithms.

Dunton, Elizabeth M.

1995-03-01

224

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

225

Laboratory longitudinal diffusion tests: 2. Parameter estimation by inverse analysis.  

PubMed

This study focuses on the verification of test interpretations for different state analyses of diffusion experiments. Part 1 of this study identified that steady, quasi-steady and equilibrium state analyses for the through- and in-diffusion tests with solution reservoirs are generally feasible where the tracer is not highly sorptive. In Part 2 we investigate parameter identifiability in transient-state analysis of reservoir concentration variation using a numerical approach. For increased generality, the analytical models, objective functions and Jacobian matrix necessary for inverse analysis of transient-state data are reformulated using unified dimensionless parameters. In these dimensionless forms, the number of unknown parameters is reduced and a single dimensionless parameter represents the sorption property. The dimensionless objective functions are evaluated for individual test methods and parameter identifiability is discussed in relation to the sorption property. The effects of multiple minima and measurement error on parameter identifiability are also investigated. The main findings are that inverse problems for inlet and outlet reservoir concentration analyses are generally unstable and well-posed, respectively. Where the tracer is sorptive, the inverse problem for the inlet reservoir concentration analysis may have multiple minima. When insufficient measurement data is collected, multiple solutions may result and this should be taken into consideration when inversely analyzing data including that of inlet reservoir concentration. Verification of test interpretation by cross-checking different state analyses is feasible where the tracer is not highly sorptive. In an actual experiment, test interpretation validity is demonstrated through consistency between theory and practice for different state analyses. PMID:18353488

Takeda, M; Zhang, M; Nakajima, H; Hiratsuka, T

2008-04-28

226

Humanlike Movements of Robotic Arms with Redundant DOFs: Virtual Spring-damper Hypothesis to Tackle the Bernstein Problem  

Microsoft Academic Search

A natural control method for resolving the ill-posedness of inverse kinematics of multi-joint reaching movements under redundancy of degrees-of-freedom (DOF) is proposed, which need neither introduce any artificial performance index to determine the inverse kinematics uniquely nor calculate the pseudo-inverse of the Jacobian of task coordinates with respect to joint coordinates. The control signal is composed of a linear superposition

Suguru Arimoto; Masahiro Sekimoto

2006-01-01

227

Paracentric inversions in man.  

PubMed Central

We have reviewed 50 cases of paracentric inversions. Of these 34 were familial with 62 phenotypically normal carrier relatives. Twenty of the 50 were discovered fortuitously. There were two reports of children with easily recognised unbalanced karyotypes resulting from a paracentric inversion in one of the parents. The vast majority of paracentric inversions are harmless. The risk of abnormal children for paracentric inversion heterozygotes is low but increases with the finding of recurrent abortions or abnormal children or both in other carriers in the family. We emphasise the need for caution in interpreting the results of antenatal diagnosis because of the variety of unexpected unbalanced chromosome types that can result from a paracentric inversion, and the difficulty in recognising, with confidence, minute differences (for the detection of which very high resolution banding is required) between apparently similar parental and fetal inversions. PMID:6392555

Madan, K; Seabright, M; Lindenbaum, R H; Bobrow, M

1984-01-01

228

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

229

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

230

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

231

Kinematics of eye movement control.  

PubMed

In this paper a kinematic description of the restrictions imposed on the eye movements is presented. The restrictions arise from a pattern of nonlinear interactions between desired changes in viewing direction and current eye position. It is shown that various reported relations between eye torsion and viewing direction can be derived by changing only the relative weights of the interactions terms. This descriptive scheme may help to elucidate the control of eye torsion in the brainstem. PMID:7784439

van den Berg, A V

1995-05-22

232

Non-universal relativistic kinematics  

E-print Network

We present a systematic derivation of the constraints that the relativity principle imposes between coefficients of a deformed (but rotational invariant) momentum composition law, dispersion relation, and momentum transformation laws, at first order in a power expansion of an ultraviolet energy scale. This work generalizes previous results to the case of particle-dependent relativistic kinematics, which can have interesting phenomenological applications that we explore in the second part of the manuscript.

J. M. Carmona; J. L. Cortes; B. Romeo

2014-12-19

233

Planar Kinematics of Rigid Bodies  

Microsoft Academic Search

\\u000a In this chapter background material on the planar kinematics of rigid bodies is presented. In particular, we show how to establish\\u000a certain useful representations for the velocity and acceleration vectors of any material point of a rigid body.We also discuss\\u000a the angular velocity vector of a rigid body. These concepts are illustrated using two important applications: mechanisms and\\u000a rolling rigid

Oliver M. O’Reilly

234

INVERSE STABLE SUBORDINATORS  

PubMed Central

The inverse stable subordinator provides a probability model for time-fractional differential equations, and leads to explicit solution formulae. This paper reviews properties of the inverse stable subordinator, and applications to a variety of problems in mathematics and physics. Several different governing equations for the inverse stable subordinator have been proposed in the literature. This paper also shows how these equations can be reconciled. PMID:25045216

MEERSCHAERT, MARK M.; STRAKA, PETER

2013-01-01

235

Uplifting Amplitudes in Special Kinematics  

E-print Network

We consider scattering amplitudes in planar N = 4 supersymmetric Yang-Mills theory in special kinematics where all external four-dimensional momenta are restricted to a (1+1)-dimensional subspace. The amplitudes are known to satisfy non-trivial factorisation properties arising from multi-collinear limits, which we further study here. We are able to find a general solution to these multi-collinear limits. This results in a simple formula which represents an n-point superamplitude in terms of a linear combination of functions S_m which are constrained to vanish in all appropriate multi-collinear limits. These collinear-vanishing building blocks, S_m, are dual-conformally-invariant functions which depend on the reduced m-point kinematics with 8 \\leq m \\leq 4l. For MHV amplitudes they can be constructed directly using, for example, the approach in Ref. [1]. This procedure provides a universal uplift of lower-point collinearly vanishing building blocks S_m to all higher-point amplitudes. It works at any loop-level l \\geq 1 and for any MHV or N^kMHV amplitude. We compare this with explicit examples involving n-point MHV amplitudes at 2-loops and 10-point MHV amplitudes at 3-loops. Tree-level superamplitudes have different properties and are treated separately from loop-level amplitudes in our approach. To illustrate this we derive an expression for n-point tree-level NMHV amplitudes in special kinematics.

Timothy Goddard; Paul Heslop; Valentin V. Khoze

2012-05-15

236

Statistical inverse problems  

NASA Astrophysics Data System (ADS)

The article discusses the discretization of linear inverse problems. When an inverse problem is formulated in terms of infinite-dimensional function spaces and then discretized for computational purposes, a discretization error appears. Since inverse problems are typically ill-posed, neglecting this error may have serious consequences to the quality of the reconstruction. The Bayesian paradigm provides tools to estimate the statistics of the discretization error that is made part of the measurement and modelling errors of the estimation problem. This approach also provides tools to reduce the dimensionality of inverse problems in a controlled manner. The ideas are demonstrated with a computed example.

Kaipio, Jari; Somersalo, Erkki

2007-01-01

237

Motion Control of Hyper Redundant Robots by Learning Control Based on Linear Combination of Error History and Initial Configuration Optimization with Backward Learning  

Microsoft Academic Search

This paper describes the motion control of hyper redundant robots using a learning control scheme based on linear combination of error history. The learning control scheme is formulated with three elements: general solution of inverse kinematics with pseudo inverse of Jacobian matrix to achieve main task, condition to achieve several subtasks and compensation by linear combination of obtained time history

Daisuke Matsuura; Nobuyuki Iwatsuki

2008-01-01

238

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

239

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

240

Teaching about Inverse Functions  

ERIC Educational Resources Information Center

In their sections on inverses most precalculus texts emphasize an algorithm for finding f [superscript -1] given f. However, inspection of precalculus and calculus texts shows that students will never again use the algorithm, which suggests the textbook emphasis may be misplaced. Inverses appear primarily when equations need to be solved, which…

Esty, Warren

2005-01-01

241

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

242

Jacobian-Free Newton-Krylov Discontinuous Galerkin (JFNK-DG) Method and Its Physics-Based Preconditioning for All-Speed Flows  

Microsoft Academic Search

The Discontinuous Galerkin (DG) method for compressible fluid flows is incorporated into the Jacobian-Free Newton-Krylov (JFNK) framework. Advantages of combining the DG with the JFNK are two-fold: a) enabling robust and efficient high-order-accurate modeling of all-speed flows on unstructured grids, opening the possibility for high-fidelity simulation of nuclear-power-industry-relevant flows; and b) ability to tightly, robustly and high-order-accurately couple with other

Robert Nourgaliev; Dana Knoll

2007-01-01

243

Optimal Trajectory Planning for Wheeled Mobile Robots Based on Kinematics Singularity  

Microsoft Academic Search

This research introduces a new optimality criterion for motion planning of wheeled mobile robots based on a cost index that assesses the nearness to singularity of forward and\\u000a inverse kinematic models. Slip motions, infinite estimation error and impossible control actions are avoided escaping from singularities. In addition, high amplification of wheel velocity errors and high wheel velocity values are\\u000a also

Luis Gracia; Josep Tornero

2008-01-01

244

The brown dwarf kinematics project  

NASA Astrophysics Data System (ADS)

Brown dwarfs are a recent addition to the plethora of objects studied in Astronomy. With theoretical masses between 13 and 75 MJupiter , they lack sustained stable Hydrogen burning so they never join the stellar main sequence. They have physical properties similar to both planets and low-mass stars so studies of their population inform on both. The distances and kinematics of brown dwarfs provide key statistical constraints on their ages, moving group membership, absolute brightnesses, evolutionary trends, and multiplicity. Yet, until my thesis, fundamental measurements of parallax and proper motion were made for only a relatively small fraction of the known population. To address this deficiency, I initiated the Brown Dwarf Kinematics (BDKP). Over the past four years I have re-imaged the majority of spectroscopically confirmed field brown dwarfs (or ultracool dwarfs---UCDs) and created the largest proper motion catalog for ultracool dwarfs to date. Using new astrometric information I examined population characteristics such as ages calculated from velocity dispersions and correlations between kinematics and colors. Using proper motions, I identified several new wide co-moving companions and investigated binding energy (and hence formation) limitations as well as the frequency of hierarchical companions. Concurrently over the past four years I have been conducting a parallax survey of 84 UCDs including those showing spectral signatures of youth, metal-poor brown dwarfs, and those within 20 pc of the Sun. Using absolute magnitude relations in J,H, and K, I identified overluminous binary candidates and investigated known flux-reversal binaries. Using current evolutionary models, I compared the MK vs J-K color magnitude diagram to model predictions and found that the low-surface gravity dwarfs are significantly red-ward and underluminous of predictions and a handful of late-type T dwarfs may require thicker clouds to account for their scatter.

Faherty, Jackie K.

2010-10-01

245

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

246

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

NASA Astrophysics Data System (ADS)

We have implemented the Jacobian-free Newton-Krylov (JFNK) method for solving the first-order ice sheet momentum equation in order to improve the numerical performance of the Glimmer-Community Ice Sheet Model (Glimmer-CISM), the land ice component of the Community Earth System Model (CESM). Our JFNK implementation is based on significant re-use of existing code. For example, our physics-based preconditioner uses the original Picard linear solver in Glimmer-CISM. For several test cases spanning a range of geometries and boundary conditions, our JFNK implementation is 1.8-3.6 times more efficient than the standard Picard solver in Glimmer-CISM. Importantly, this computational gain of JFNK over the Picard solver increases when refining the grid. Global convergence of the JFNK solver has been significantly improved by rescaling the equation for the basal boundary condition and through the use of an inexact Newton method. While a diverse set of test cases show that our JFNK implementation is usually robust, for some problems it may fail to converge with increasing resolution (as does the Picard solver). Globalization through parameter continuation did not remedy this problem and future work to improve robustness will explore a combination of Picard and JFNK and the use of homotopy methods.

Lemieux, Jean-François; Price, Stephen F.; Evans, Katherine J.; Knoll, Dana; Salinger, Andrew G.; Holland, David M.; Payne, Antony J.

2011-07-01

247

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

248

An alternative method to solving the kinematics of a redundant robot  

SciTech Connect

The state occupied by an m-degrees-of-freedom robot is determined by an articular joint position vector q of R{sup m}, but usually the specification of a task by its task-vector X takes place in the operational space R{sup n}. Controlling the kinematics of a robot requires finding q as a function of X. In most cases, it is impossible to obtain this relationship analytically and globally. The authors suggest an algorithm that exploits the linear properties of the coordinate transformation in the neighborhood of the point q expressed by the Jacobian matrix J and its s = C{sub m}{sup n} submatrices J{sub 1}, J{sub 2},..., J{sub k}, ..., J{sub s} of dimension n {times} n. The algorithm has been applied to the planar arm illustrated in the paper, using the symbolic manipulation environment Mathematica on Macintosh II. This scheme can be efficiently parallelized and contains well-behaved matrices for numerical processing with a computer. Generalization of the algorithm to other criteria is planned.

Belmans, P.; Culioli, J. (Oak Ridge National Lab., TN (USA))

1990-06-01

249

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

NASA Astrophysics Data System (ADS)

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

250

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

251

Inversion of marine multifrequency electromagnetic profiling data: a new approach to resolve surficial sediment stratification  

NASA Astrophysics Data System (ADS)

Electromagnetic induction (EMI) methods are widely used on land to map electric conductivity and/or magnetic susceptibility distributions of surficial sediments. In contrast, the application of these methods in marine environments is relatively novel. Based on the recently developed electromagnetic benthic profiler MARUM-NERIDIS III we investigate the potential of concentric-loop EMI methods to recover conductivity and susceptibility of layered marine sediments. Sensitivity analyses based on a data and model normalized Jacobian matrix were performed to compare the influence of conductivity and susceptibility to in-phase and quadrature components at different frequencies. Both parameters substantially affect the EM response. However, the influence of susceptibility decreases more with depth and offers lower depth resolution than that of conductivity. A 1-D inversion algorithm to reconstruct vertical conductivity distributions was developed from existing non-linear inversion methods using apparent conductivity and apparent susceptibility recovered from simultaneous half-space inversion as a priori information. This algorithm was tested on synthetic and real marine EM data from a commercial multifrequency concentric loop EMI system (GEM-3). The results indicate that our inversion algorithm yields meaningful results down to approximately 3 m depth under typical shallow marine conditions. The comparison of inversion results recovered with 1-D and 2-D constraints showed that combining lateral with vertical constraints substantially improves the resolution of the inversion outputs. Field data from the NW Iberian shelf was calibrated according to a processing flow specifically designed for underwater conditions and analysed. Inversion outputs are in good agreement with ground-truthing stratigraphic investigations and deliver relevant clues on past and present sediment dynamics.

Baasch, B.; Müller, H.; Oberle, F. K. J.; Dobeneck, T. von

2014-01-01

252

Sampling-based exploration of folded state of a protein under kinematic and geometric constraints.  

PubMed

Flexibility is critical for a folded protein to bind to other molecules (ligands) and achieve its functions. The conformational selection theory suggests that a folded protein deforms continuously and its ligand selects the most favorable conformations to bind to. Therefore, one of the best options to study protein-ligand binding is to sample conformations broadly distributed over the protein-folded state. This article presents a new sampler, called kino-geometric sampler (KGS). This sampler encodes dominant energy terms implicitly by simple kinematic and geometric constraints. Two key technical contributions of KGS are (1) a robotics-inspired Jacobian-based method to simultaneously deform a large number of interdependent kinematic cycles without any significant break-up of the closure constraints, and (2) a diffusive strategy to generate conformation distributions that diffuse quickly throughout the protein folded state. Experiments on four very different test proteins demonstrate that KGS can efficiently compute distributions containing conformations close to target (e.g., functional) conformations. These targets are not given to KGS, hence are not used to bias the sampling process. In particular, for a lysine-binding protein, KGS was able to sample conformations in both the intermediate and functional states without the ligand, while previous work using molecular dynamics simulation had required the ligand to be taken into account in the potential function. Overall, KGS demonstrates that kino-geometric constraints characterize the folded subset of a protein conformation space and that this subset is small enough to be approximated by a relatively small distribution of conformations. PMID:21971749

Yao, Peggy; Zhang, Liangjun; Latombe, Jean-Claude

2012-01-01

253

Inversion with early photons.  

PubMed

Optical tomography using early photons can improve resolution and reduce the ill-posed nature of the inversion problem. In this work we use 360 degrees projection experimental data to investigate the inversion performance of three commonly used numerical inversion methods: the random algebraic reconstruction technique (rART), singular value decomposition (SVD), and the conjugate-gradient-type method LSQR. Results are contrasted to each other and the effects of different photon propagation models are also investigated. We find that all methods perform adequately given appropriate regularization parameters, and that an experimentally measured photon weight function yields superior results over two approximate weights that have been previously used. PMID:17500472

Turner, Gordon M; Soubret, Antoine; Ntziachristos, Vasilis

2007-04-01

254

Ballistic representation for kinematic access  

NASA Astrophysics Data System (ADS)

This work uses simple two-body orbital dynamics to initially determine the kinematic access for a ballistic vehicle. Primarily this analysis was developed to assess when a rocket body might conjunct with an orbiting satellite platform. A family of access opportunities can be represented as a volume for a specific rocket relative to its launch platform. Alternately, the opportunities can be represented as a geographical footprint relative to aircraft or satellite position that encompasses all possible launcher locations for a specific rocket. A thrusting rocket is treated as a ballistic vehicle that receives all its energy at launch and follows a coasting trajectory. To do so, the rocket's burnout energy is used to find its equivalent initial velocity for a given launcher's altitude. Three kinematic access solutions are then found that account for spherical Earth rotation. One solution finds the maximum range for an ascent-only trajectory while another solution accommodates a descending trajectory. In addition, the ascent engagement for the descending trajectory is used to depict a rapid access scenario. These preliminary solutions are formulated to address ground-, sea-, or air-launched vehicles.

Alfano, Salvatore

2011-01-01

255

Are undesirable contact kinematics minimized after kinematically aligned total knee arthroplasty? An intersurgeon analysis  

E-print Network

-Verlag Berlin Heidelberg 2012 Abstract Purpose Tibiofemoral contact kinematics or knee implant motions haveKNEE Are undesirable contact kinematics minimized after kinematically aligned total knee a direct influence on patient function and implant longevity and should be evaluated for any new alignment

Hull, Maury

256

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

257

Inverse dynamics analysis and application of a 4DOF hybrid machine tool  

Microsoft Academic Search

This paper presents the dynamics of a four degrees of freedom (DOF) hybrid machine tool based on a novel planar 3-DOFs parallel manipulator and a long movement of the worktable. Closed-form solution is developed for the inverse kinematics about the parallel manipulator. The dynamics model of the parallel manipulator is built, which includes the extensible strut, sliders and balances model.

Xiaoqiang Tang; Peiqing Ye; Jinsong Wang

2003-01-01

258

Inverse Dynamics Analysis and Trajectory Generation of Incompletely Restrained Wire-Suspended Mechanisms  

Microsoft Academic Search

Discusses an inverse dynamics problem and proposes a trajectory generation method for wire-suspended mechanisms. The wire-suspended mechanisms are classified into two types, which are completely restrained type mechanisms and incomplete by restrained type mechanisms. For the incompletely restrained type mechanisms, consideration of dynamics is important, because the motion of this mechanism is governed by its dynamics and kinematics, whereas the

Noritaka Yanai; Motoji Yamamoto; Akira Mohri

2001-01-01

259

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

260

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

261

Time-lapse three-dimensional inversion of complex conductivity data using an active time constrained (ATC) approach  

USGS Publications Warehouse

Induced polarization (more precisely the magnitude and phase of impedance of the subsurface) is measured using a network of electrodes located at the ground surface or in boreholes. This method yields important information related to the distribution of permeability and contaminants in the shallow subsurface. We propose a new time-lapse 3-D modelling and inversion algorithm to image the evolution of complex conductivity over time. We discretize the subsurface using hexahedron cells. Each cell is assigned a complex resistivity or conductivity value. Using the finite-element approach, we model the in-phase and out-of-phase (quadrature) electrical potentials on the 3-D grid, which are then transformed into apparent complex resistivity. Inhomogeneous Dirichlet boundary conditions are used at the boundary of the domain. The calculation of the Jacobian matrix is based on the principles of reciprocity. The goal of time-lapse inversion is to determine the change in the complex resistivity of each cell of the spatial grid as a function of time. Each model along the time axis is called a 'reference space model'. This approach can be simplified into an inverse problem looking for the optimum of several reference space models using the approximation that the material properties vary linearly in time between two subsequent reference models. Regularizations in both space domain and time domain reduce inversion artefacts and improve the stability of the inversion problem. In addition, the use of the time-lapse equations allows the simultaneous inversion of data obtained at different times in just one inversion step (4-D inversion). The advantages of this new inversion algorithm are demonstrated on synthetic time-lapse data resulting from the simulation of a salt tracer test in a heterogeneous random material described by an anisotropic semi-variogram. ?? 2011 The Authors Geophysical Journal International ?? 2011 RAS.

Karaoulis, M.; Revil, A.; Werkema, D.D.; Minsley, B.J.; Woodruff, W.F.; Kemna, A.

2011-01-01

262

Geometry, kinematics, and mechanics of decollement folding  

Microsoft Academic Search

Despite much previous research, important issues regarding the geometry, kinematics, and mechanics of decollement folding remain unaddressed. This dissertation presents the results of investigations into problems regarding the geometric, kinematic, and mechanical evolution of decollement folds using empirical, analog modelling and theoretical approaches. Displacement-distance analysis of fault propagation, fault bend, and decollement fold models reveals that displacement gradients on fault

Christopher Alan Hedlund

1997-01-01

263

Kinematic Event Patterns in Speech: Special Problems.  

ERIC Educational Resources Information Center

Results from a new analysis of synchronous acoustic and fleshpoint-kinematic data, recorded from 53 normal young-adult speakers of American English, are reported. The kinematic data represent speech-related actions of the tongue blade and dorsum, both lips, and the mandible, during the test words, "special" and "problem," and were drawn from an…

Westbury, John R.; Severson, Elizabeth J.; Lindstrom, Mary J.

2000-01-01

264

The Stellar Kinematic Fields of NGC 3379  

Microsoft Academic Search

We have measured the stellar kinematic profiles of NGC 3379 along four position angles, using absorption lines in spectra obtained with the Multiple Mirror Telescope. We derive a far more detailed description of the kinematic fields through the main body of the galaxy than could be obtained from previous work. Our data extend 90\\

Thomas S. Statler; Tammy Smecker-Hane

1999-01-01

265

Kinematics of Healthy and Meniscal Repaired Knees  

Microsoft Academic Search

Differences have been reported between in vitro and in vivo meniscal kinematics, and no clinical study to date has investigated the effect of meniscal repair on meniscal kinematics. Eleven subjects with healthy knees and eight subjects who had undergone meniscal repair for an isolated tear were scanned using magnetic resonance imaging. Sagittal plane scanning was performed at 0, 30, 60,

Marcia Epler; Michael Sitler; Raymond Moyer

2005-01-01

266

Evolving Body Kinematics for Virtual Characters  

Microsoft Academic Search

Physically-based character animation systems often require complex knowledge of the underlying equations of motion. Hence, producing physically- realistic animations can be time consuming with these systems. In this paper, we present an approach that automatically searches for kinematics solutions for virtual characters. Characters learn their locomotion by evolving body kinematics. We designed two different control architectures for the character's learning

C. Gatzoulis; W. Tang; W. J. Stoddart

267

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

268

Configuration independent kinematics for modular robots  

Microsoft Academic Search

A modular robotic system consists of standardized joint and link units that can be assembled into a number of different kinematic configurations. This paper describes the design and kinematic issues of a newly developed modular robot aimed for assembly tasks. All modules are designed as cubic units. There are connecting interfaces, termed connecting ports, on all faces of the cubes

I-Ming Chen; Guilin Yang

1996-01-01

269

Conformational analysis of molecular chains using nano-kinematics.  

PubMed

We present algorithms for 3-D manipulation and conformational analysis of molecular chains, when bond lengths, bond angles and related dihedral angles remain fixed. These algorithms are useful for local deformations of linear molecules, exact ring closure in cyclic molecules and molecular embedding for short chains. Other possible applications include structure prediction, protein folding, conformation energy analysis and 3D molecular matching and docking. The algorithms are applicable to all serial molecular chains and make no assumptions about their geometry. We make use of results on direct and inverse kinematics from robotics and mechanics literature and show the correspondence between kinematics and conformational analysis of molecules. In particular, we pose these problems algebraically and compute all the solutions making use of the structure of these equations and matrix computations. The algorithms have been implemented and perform well in practice. In particular, they take tens of milliseconds on current workstations for local deformations and chain closures on molecular chains consisting of six or fewer rotatable dihedral angles. PMID:7796278

Manocha, D; Zhu, Y; Wright, W

1995-02-01

270

A Kinematically Consistent Two-Point Correlation Function  

NASA Technical Reports Server (NTRS)

A simple kinematically consistent expression for the longitudinal two-point correlation function related to both the integral length scale and the Taylor microscale is obtained. On the inner scale, in a region of width inversely proportional to the turbulent Reynolds number, the function has the appropriate curvature at the origin. The expression for two-point correlation is related to the nonlinear cascade rate, or dissipation epsilon, a quantity that is carried as part of a typical single-point turbulence closure simulation. Constructing an expression for the two-point correlation whose curvature at the origin is the Taylor microscale incorporates one of the fundamental quantities characterizing turbulence, epsilon, into a model for the two-point correlation function. The integral of the function also gives, as is required, an outer integral length scale of the turbulence independent of viscosity. The proposed expression is obtained by kinematic arguments; the intention is to produce a practically applicable expression in terms of simple elementary functions that allow an analytical evaluation, by asymptotic methods, of diverse functionals relevant to single-point turbulence closures. Using the expression devised an example of the asymptotic method by which functionals of the two-point correlation can be evaluated is given.

Ristorcelli, J. R.

1998-01-01

271

Quantum trajectories from kinematic considerations  

NASA Astrophysics Data System (ADS)

We present a method in which one can infer deterministic particle trajectories for quantum mechanics using just the time evolving probability density ? = ?*? and without assuming or solving any equations of motion. The approach utilizes the geometrical construction of centroidal Voronoi tessellations (CVT). In one dimension the CVT trajectories are shown to be identical to the particle trajectories of Bohm's quantum mechanics. Several two-dimensional numerical examples are given in which the resulting CVT trajectories are highly correlated with Bohm's trajectories. The method also allows the formation of trajectories for classical probability densities, for which the resulting trajectories are not, in general, the physically observed trajectories. Rather, they are hydrodynamic trajectories which kinematically depict the evolving density.

Coffey, T. M.; Wyatt, R. E.; Schieve, W. C.

2010-08-01

272

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

273

Traction Control for a Rocker-Bogie Robot with Wheel-Ground Contact Angle Estimation  

Microsoft Academic Search

A method for kinematics modeling of a six-wheel Rocker-Bogie mobile robot is described in detail. The forward kinematics is\\u000a derived by using wheel Jacobian matrices in conjunction with wheel-ground contact angle estimation. The inverse kinematics\\u000a is to obtain the wheel velocities and steering angles from the desired forward velocity and turning rate of the robot. Traction\\u000a Control is also developed

Mongkol Thianwiboon; Viboon Sangveraphunsiri

2005-01-01

274

TWO UNCONVENTIONAL APPROACHES TO ELECTROMAGNETIC INVERSION  

E-print Network

TWO UNCONVENTIONAL APPROACHES TO ELECTROMAGNETIC INVERSION Hierarchical Bayesian Inversion and Head, Department of Geophysics ii #12;ABSTRACT Electromagnetic methods are effective complementary approaches of electromagnetic inversion: hier- archical Bayesian inversion and inverse scattering series. We

Snieder, Roel

275

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

276

Recursive inverse factorization.  

PubMed

A recursive algorithm for the inverse factorization S(-1)=ZZ(*) of Hermitian positive definite matrices S is proposed. The inverse factorization is based on iterative refinement [A.M.N. Niklasson, Phys. Rev. B 70, 193102 (2004)] combined with a recursive decomposition of S. As the computational kernel is matrix-matrix multiplication, the algorithm can be parallelized and the computational effort increases linearly with system size for systems with sufficiently sparse matrices. Recent advances in network theory are used to find appropriate recursive decompositions. We show that optimization of the so-called network modularity results in an improved partitioning compared to other approaches. In particular, when the recursive inverse factorization is applied to overlap matrices of irregularly structured three-dimensional molecules. PMID:18345875

Rubensson, Emanuel H; Bock, Nicolas; Holmström, Erik; Niklasson, Anders M N

2008-03-14

277

Acoustic to articulatory inversion  

E-print Network

The context of this work is speech analysis. The subject deals with acoustic-to-articulatory inversion, i.e. the recovery of the temporal evolution of the vocal tract shape from the signal. This topic is important because it is likely to give rise to applications in the domains of speech coding as well as second language learning. Acoustic-to-articulatory inversion relies on an analysis by synthesis approach. The synthesis is the articulatory synthesis, which, from the vocal tract shape given by an articulatory model specifying the position and shape of the tongue, lowers jaw, lips and larynx produces the acoustical signal by means of an acoustical simulation. This synthesis system is used to build a table consisting of pairs of articulatory and acoustical vectors[1]. During inversion, all the articulatory shapes whose acoustic parameters are close to those observed in the original speech signal. 2

unknown authors

278

Electromagnetic inverse scattering  

NASA Technical Reports Server (NTRS)

A three-dimensional electromagnetic inverse scattering identity, based on the physical optics approximation, is developed for the monostatic scattered far field cross section of perfect conductors. Uniqueness of this inverse identity is proven. This identity requires complete scattering information for all frequencies and aspect angles. A nonsingular integral equation is developed for the arbitrary case of incomplete frequence and/or aspect angle scattering information. A general closed-form solution to this integral equation is developed, which yields the shape of the scatterer from such incomplete information. A specific practical radar solution is presented. The resolution of this solution is developed, yielding short-pulse target resolution radar system parameter equations. The special cases of two- and one-dimensional inverse scattering and the special case of a priori knowledge of scatterer symmetry are treated in some detail. The merits of this solution over the conventional radar imaging technique are discussed.

Bojarski, N. N.

1972-01-01

279

Estimation of near-surface shear-wave velocity by inversion of Rayleigh waves  

USGS Publications Warehouse

The shear-wave (S-wave) velocity of near-surface materials (soil, rocks, pavement) and its effect on seismic-wave propagation are of fundamental interest in many groundwater, engineering, and environmental studies. Rayleigh-wave phase velocity of a layered-earth model is a function of frequency and four groups of earth properties: P-wave velocity, S-wave velocity, density, and thickness of layers. Analysis of the Jacobian matrix provides a measure of dispersion-curve sensitivity to earth properties. S-wave velocities are the dominant influence on a dispersion curve in a high-frequency range (>5 Hz) followed by layer thickness. An iterative solution technique to the weighted equation proved very effective in the high-frequency range when using the Levenberg-Marquardt and singular-value decomposition techniques. Convergence of the weighted solution is guaranteed through selection of the damping factor using the Levenberg-Marquardt method. Synthetic examples demonstrated calculation efficiency and stability of inverse procedures. We verify our method using borehole S-wave velocity measurements.Iterative solutions to the weighted equation by the Levenberg-Marquardt and singular-value decomposition techniques are derived to estimate near-surface shear-wave velocity. Synthetic and real examples demonstrate the calculation efficiency and stability of the inverse procedure. The inverse results of the real example are verified by borehole S-wave velocity measurements.

Xia, J.; Miller, R.D.; Park, C.B.

1999-01-01

280

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

281

Kinematic modeling of folding above listric propagating thrusts  

NASA Astrophysics Data System (ADS)

We describe a kinematic approach to simulate folds above listric propagating thrusts. The model is based on a pre-defined circular thrust geometry with a maximum central angle beyond which the thrust is planar, inclined shear above the circular thrust, and trishear in front of the thrust. Provided the trajectory of thrust propagation is established, the model can be run forward and backwards. We use this last feature to implement a global simulated annealing, inverse modeling strategy. This inverse modeling strategy is applied to synthetic folds as well as two real examples in offshore Venezuela and the Niger Delta toe-thrust system. These three examples illustrate the benefits of the algorithm, particularly in predicting the possible range of models that can fit the structures. Thrust geometry, depth to detachment level, and backlimb geometry have high impact in model parameters such as backlimb shear angle and fault slip; while forelimb geometry is critical to constrain parameters such as fault propagation to fault slip ratio and trishear angle. Steep to overturned beds in forelimb areas are often not imaged by seismic, so in the absence of additional well data, considering all possible thrust-fold geometries is critical for the modeling and whatever prediction (e.g. hydrocarbon trap integrity) is made from it.

Cardozo, Nestor; Brandenburg, J. P.

2014-03-01

282

Kinematic determinants of human locomotion.  

PubMed Central

1. The aim of this study was to find kinematic patterns that are invariant across the normal range of locomotion speeds. Subjects walked at different, freely chosen speeds ranging from 0.9 to 2.1 m s-1, while motion and ground reaction forces on the right side of the body were recorded in three-dimensional space. 2. The time course of the anatomical angles of flexion-extension at the hip and ankle was variable not only across subjects, but even from trial to trial in the same subject. By contrast, the time course of the changes in the angles of elevation of each limb segment (pelvis, thigh, shank and foot) relative to the vertical was stereotyped across subjects. 3. To compare the waveforms across speeds, data were scaled in time relative to gait cycle duration. The pattern of ground reaction forces was highly speed dependent. Several distinct families of curves could be recognized in the flexion-extension angles at the hip and ankle. Instead, the waveforms of global length and elevation of the limb, elevation angles of all limb segments and flexion-extension at the knee were invariant with speed. 4. When gait trajectories at all speeds are plotted in the position space defined by the elevation angles of the limb segments, they describe regular loops on a plane. The statistical characteristics of these angular covariations were quantified by means of principal component analysis. The first two principal components accounted together for > 99% of the total experimental variance, and were quantitatively comparable in all subjects. 5. This constraint of planar covariation of the elevation angles is closely reminiscent of that previously described for the control of posture. The existence of laws of intersegmental co-ordination, common to the control of posture and locomotion, presumably assures the maintenance of dynamic equilibrium during forward progression, and the anticipatory adaptation to potentially destabilizing factors by means of co-ordinated kinematic synergies of the whole body. Images Figure 1 PMID:8865081

Borghese, N A; Bianchi, L; Lacquaniti, F

1996-01-01

283

Reducing nonuniqueness in finite source inversion using rotational ground motions  

NASA Astrophysics Data System (ADS)

We assess the potential of rotational ground motion recordings to reduce nonuniqueness in kinematic source inversions, with emphasis on the required measurement accuracy of currently developed rotation sensors. Our analysis is based on synthetic Bayesian finite source inversions that avoid linearizations and provide a comprehensive quantification of uncertainties and trade-offs. Using the fault and receiver geometry of the Tottori 2000 earthquake as a test bed, we perform inversions for two scenarios: In scenario I, we use translational velocity recordings only. In scenario II, we randomly replace half of the velocity recordings by rotation recordings, thus keeping the total amount of data constant. To quantify the noise-dependent impact of rotation recordings, we perform a sequence of inversions with varying noise levels of rotations relative to translations. Our results indicate that the incorporation of rotational ground motion recordings can significantly reduce nonuniqueness in finite source inversions, provided that measurement uncertainties are similar to or below the uncertainties of translational velocity recordings. When this condition is met, rupture velocity and rise time benefit most from rotation data. The trade-offs between both parameters are then strongly reduced, and the information gain nearly doubles. This suggests that rotational ground motion recordings may improve secondary inferences that rely on accurate information about rise time and rupture velocity. These include frictional properties of the fault, radiation directivity, and ground motion in general.

Bernauer, M.; Fichtner, A.; Igel, H.

2014-06-01

284

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

285

Signal approach to relativistic kinematics  

NASA Astrophysics Data System (ADS)

A formalism is developed, in which the kinematical relations among bodies are expressed in terms of observable parameters of signal transformations. These parameters are found by correlating a transmitted signal with the signal which is returned after reflection from another body. The signals are assumed to obey the principle of linear superposition and to propagate at a universal speed, namely the speed of light. The advantage of this formalism lies in the fact that the elementary physical concepts, the signals received and transmitted from an observing body, are strictly local. The case of bodies moving uniformly along a straight line is studied in detail, since this relatively simple case captures most of the relativistic features of the problem. We derive the form of the observable round trip signal operators using the constancy of the speed of light. Then auxiliary labeled operators are introduced to correspond to one way signal transformations and changes of clock reference. Formulas are derived by which any operator in this extended calculus can be computed by any given observer using only the signal parameters he can measure directly. Lorentz contraction, time dilation, the relativistic doppler effect and the velocity addition formula factor are derived in the new formalism. The extension of the model to two and three dimensions is not unique, but one technique is to introduce extended observers which are made up of point elements in a rigid arrangement. This extension is studied. The transformation law connecting a transmitted and a received multicomponent signal is found.

Mountcastle, Paul Declan

1998-10-01

286

Kinematic modeling of scanner trajectories  

NASA Astrophysics Data System (ADS)

Satellites are free-moving rigid bodies subject to various external forces which make them deviate from their predetermined positional and rotational trajectories. Since many remote sensing imaging devices use the linear pushbroom scanning model, trajectory deviation during the image scanning period causes geometric distortion in the imagery. Unless actual satellite trajectory during imaging is modeled, accurate rectification of imagery is impossible. A means of recovering the trajectory from known satellite motion is presented here. Rotational motion is usually sensed by gyroscopes which measure angular velocity. Translational motion can be determined in several ways including telemetry analysis and linear accelerometers. In more recent satellites GPS receivers may be used to determine motion data. We show how to interpolate and subsequently integrate angular velocity to yield a rotational trajectory. The screw, implemented as a dual-number quaternion, is shown to be a suitable parameterization of motion to model the trajectory as a kinematic chain. This representation is useful for image geometry analysis and hence for correction of image distortion. Applications of this parameterization to scanned image resampling and rectification are mentioned.

Shevlin, Fergal P.

1994-12-01

287

Inverse consistent non-rigid image registration based on robust point set matching  

PubMed Central

Background Robust point matching (RPM) has been extensively used in non-rigid registration of images to robustly register two sets of image points. However, except for the location at control points, RPM cannot estimate the consistent correspondence between two images because RPM is a unidirectional image matching approach. Therefore, it is an important issue to make an improvement in image registration based on RPM. Methods In our work, a consistent image registration approach based on the point sets matching is proposed to incorporate the property of inverse consistency and improve registration accuracy. Instead of only estimating the forward transformation between the source point sets and the target point sets in state-of-the-art RPM algorithms, the forward and backward transformations between two point sets are estimated concurrently in our algorithm. The inverse consistency constraints are introduced to the cost function of RPM and the fuzzy correspondences between two point sets are estimated based on both the forward and backward transformations simultaneously. A modified consistent landmark thin-plate spline registration is discussed in detail to find the forward and backward transformations during the optimization of RPM. The similarity of image content is also incorporated into point matching in order to improve image matching. Results Synthetic data sets, medical images are employed to demonstrate and validate the performance of our approach. The inverse consistent errors of our algorithm are smaller than RPM. Especially, the topology of transformations is preserved well for our algorithm for the large deformation between point sets. Moreover, the distance errors of our algorithm are similar to that of RPM, and they maintain a downward trend as whole, which demonstrates the convergence of our algorithm. The registration errors for image registrations are evaluated also. Again, our algorithm achieves the lower registration errors in same iteration number. The determinant of the Jacobian matrix of the deformation field is used to analyse the smoothness of the forward and backward transformations. The forward and backward transformations estimated by our algorithm are smooth for small deformation. For registration of lung slices and individual brain slices, large or small determinant of the Jacobian matrix of the deformation fields are observed. Conclusions Results indicate the improvement of the proposed algorithm in bi-directional image registration and the decrease of the inverse consistent errors of the forward and the reverse transformations between two images. PMID:25559889

2014-01-01

288

Inverse problems in astronomy  

Microsoft Academic Search

In many research fields the basic properties of a system have to be deduced from remotely sensed observations rather than first hand practical experiments. These remotely sensed data can, however, arrive as severely filtered convolutions of the original source function which, through integral inversion techniques, have to be transformed into meaningful, stable and unique representations of the source. The authors

I. J. D. Craig; J. C. Brown

1986-01-01

289

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

290

Inversion of triton moments  

NASA Astrophysics Data System (ADS)

We use the formalism of hyperspherical harmonics to calculate several moments for the triton photoeffect, for a Volkov spin-independent potential. First, we improve the accuracy of Maleki's calculations of the moments ?2 and ?3 by including more terms in the hyperspherical expansion. We also calculate moments ?0 and ?1 for a Serber mixture. We find reasonable agreement between our moments found by sum rules and those found from the cross sections calculated by Fang et al. and Levinger-Fitzgibbon. We then develop a technique of inversion of a finite number of moments by making the assumption that the cross section can be written as a sum of several Laguerre polynomials multiplied by a decreasing exponential. We test our inversion technique successfully on several model potentials. We then modify it and apply it to the five moments (?-1 to ?3) for a force without exchange, and find fair agreement with Fang's values of the cross section. Finally, we apply the inversion technique to our three moments (?-1,?0,and ?1) for a Serber mixture, and find reasonable agreement with Gorbunov's measurements of the 3He photoeffect. NUCLEAR REACTIONS Triton photoeffects, hyperspherical harmonics, moments of photoeffect, inversion of moments.

Clare, R. B.; Levinger, J. S.

1981-02-01

291

SAGE II inversion algorithm  

Microsoft Academic Search

The operational Stratospheric Aerosol and Gas Experiment II multichannel data inversion algorithm is described. Aerosol and ozone retrievals obtained with the algorithm are discussed. The algorithm is compared to an independently developed algorithm (Lenoble, 1989), showing that the inverted aerosol and ozone profiles from the two algorithms are similar within their respective uncertainties.

W. P. Chu; M. P. McCormick; J. Lenoble; C. Brogniez; P. Pruvost

1989-01-01

292

Inverse Paper Chromatography  

Microsoft Academic Search

Available methods of examination do not provide absolute certainty that two samples of paper have the same origin. A new technique for testing paper, known as inverse paper chromatography (IPC), is based on using a strip of paper as the chromatographic sorbent medium on which a mixture of known probes is separated under standardized conditions. The resulting chromatogram will uniquely

Irving I. Ziderman

1982-01-01

293

Step kinematic calibration of a 3DOF planar parallel kinematic machine tool  

Microsoft Academic Search

This paper presents a novel step kinematic calibration method for a 3 degree-of-freedom (DOF) planar parallel kinematic machine\\u000a tool, based on the minimal linear combinations (MLCs) of error parameters. The method using mapping of linear combinations\\u000a of parameters in error transfer multi-parameters coupling system changes the modeling, identification and error compensation\\u000a of geometric parameters in the general kinematic calibration into

Peng Chang; JinSong Wang; TieMin Li; XinJun Liu; LiWen Guan

2008-01-01

294

Optimization strategies for additional actuators of kinematically redundant parallel kinematic machines  

Microsoft Academic Search

In this paper five different optimization strategies for kinematically redundant mechanisms, i.e. mechanisms having additional actuator(s) in at least one kinematic chain, are presented. They are based on two main approaches, a discrete optimization and a classical continuous optimization. Exemplarily, a planar, kinematically redundant 3RRR-based mechanism is introduced. The position of its redundant actuator, i.e. the robot geometry, is optimized

Jens Kotlarski; Trung Do Thanh; Bodo Heimann; Tobias Ortmaier

2010-01-01

295

Constraining earthquake source inversions with GPS data: 2. A two-step approach to combine seismic and  

E-print Network

. The typical procedure to infer the evolution of slip on the fault is to solve a kinematic inverse problemConstraining earthquake source inversions with GPS data: 2. A two-step approach to combine seismic and geodetic data sets Susana Custo´dio,1,2 Morgan T. Page,3,4 and Ralph J. Archuleta1,5 Received 14 April 2008

Archuleta, Ralph

296

Kinematic analysis of 7 DOF anthropomorphic arms  

Microsoft Academic Search

A kinematic analysis of anthropomorphic 7 DOF serial link spatial manipulators with revolute joints is presented. To determine joint angles uniquely for a given end-effector position and orientation, the redundancy is parameterized by a scalar variable which corresponds to the angle between the arm plane and a reference plane. The forward kinematic mappings from joint-space to end-effector coordinates and arm

K. Kreutz-Delgado; M. Long; H. Seraji

1990-01-01

297

Dynamic analysis of a parallel kinematic planer  

Microsoft Academic Search

Parallel kinematic planer is a new type of PKM. For PKM, dynamic character analysis is important to the mechanism's control. The paper reviews the conceptions of the PKM's dynamic and its analyses method. The paper describes a kind of 4-dof parallel kinematic mechanism with D-H method. By utilizing Newton-Euler approach, the dynamic model of the mechanism is developed, and meanwhile

Liu Hongjun; Li Shuai; Wei Yingzi

2010-01-01

298

Fractionation in planar kinematic chains: Reconciling enumeration contradictions  

Microsoft Academic Search

Enumeration of kinematic chains satisfying a set of design specifications is still an open problem. Three difficulties are common in the enumeration: isomorphism, degeneration and fractionation. A lot has been said about isomorphism and degeneration but little about fractionation. Some enumeration methods apparently consider fractionated kinematic chains as degenerate kinematic chains and eliminate them. Other methods enumerate fractionated kinematic chains

D. Martins; R. Simoni; A. P. Carboni

2010-01-01

299

Chemical Tagging of Solar Neighborhood Kinematic Streams  

NASA Astrophysics Data System (ADS)

Elemental abundance measurements for lanthanum, europium, and iron are presented for 504 stars in the solar neighborhood. The bulk of the data are planet search spectra taken with HIRES on the Keck I telescope at R=50,000, but a subset of 45 kinematically selected stars were observed on the Harlan J. Smith Telescope at McDonald Observatory at R=60,000 and S/N=100 at the 3988 angstrom lanthanum line and S/N=250 around 5240 angstrom near the iron lines. Statistical analyses of stellar kinematics in the solar neighborhood reveal much kinematic substructure in the disk, though it is not readily apparent whether this substructure is extragalactic or dynamical in origin. Much of the substructure can be quickly identified as well known moving groups of stars such as the Hercules, Sirius, and Hyades stellar streams. Additionally, the subset of kinematically selected stars observed at McDonald Observatory are members of a stellar stream putatively identified by Amina Helmi as part of a merger remnant. Taking advantage of a large data set and a homogeneous spectral analysis, a Kolmogorov-Smirnov hypothesis test is applied to investigate the possibility that these kinematic structures are chemically distinct from the Galactic Disk. In all cases, the kinematic streams have chemistries roughly consistent with the Galactic disk trends, although the statistical analyses suggest some subtle variations. The accretion hypothesis is not completely ruled out for Helmi's stream, but the chemical variations are interpreted primarily in terms of dynamical effects.

Stringer, Christopher Bayard

300

Major role of shear heating in intracontinental inverted metamorphism: Inference from a thermo-kinematic parametric study  

NASA Astrophysics Data System (ADS)

Inverted metamorphism corresponds to the stacking of high-temperature metamorphic units structurally on top of lower-temperature units and is commonly observed along main thrusts in major orogens. Yet, in spite of many existing models, the origin and preservation of the metamorphic inversion in intracontinental collision belts is still debated. In this study, we use a crustal-scale 2D thermo-kinematic model in order to investigate the key parameters controlling the inversion of the geothermal gradient at crustal scale. Our results confirm that the kinematic framework strongly impacts the thermal evolution around the thrust. Erosion velocity and thermal conductivity of rocks are two parameters that control the spatial location of the thermal perturbation and the intensity of inversion, respectively. However, even in extreme kinematic configurations, i.e., convergence velocities > 3cm/yr and relatively high thrust dip angles ~ 30°, the thermal inversion is fleeting and thrust temperatures cannot reach the high temperature peak values characteristic of natural occurences (> 600°C) if shear heating is not taken into account. Conversion of mechanical energy into heat represents a main contribution to the thermal budget along main crustal shear zones. It leads to high temperature conditions in the thrust zone and our results attest that it is the only process that allows the preservation through time of an intense thermal inversion. Our quantification shows that shear heating is much more efficient than other processes such as accretion and surface denudation and is compatible with the observations of inverted metamorphism in the Himalayan or Variscan belts, for example. This comparison with natural occurrences suggests that the formation and preservation of intracontinental thermal inversion require shear zone viscosity values of the order of 1e20-1e21 Pa.s for convergence velocities between 1 and 3 cm/yr.

Duprat-Oualid, Sylvia; Yamato, Philippe; Pitra, Pavel

2014-05-01

301

Statistical Methods for Estimation of Direct and Differential Kinematics of the Vocal Tract  

PubMed Central

We present and evaluate two statistical methods for estimating kinematic relationships of the speech production system: Artificial Neural Networks and Locally-Weighted Regression. The work is motivated by the need to characterize this motor system, with particular focus on estimating differential aspects of kinematics. Kinematic analysis will facilitate progress in a variety of areas, including the nature of speech production goals, articulatory redundancy and, relatedly, acoustic-to-articulatory inversion. Statistical methods must be used to estimate these relationships from data since they are infeasible to express in closed form. Statistical models are optimized and evaluated – using a heldout data validation procedure – on two sets of synthetic speech data. The theoretical and practical advantages of both methods are also discussed. It is shown that both direct and differential kinematics can be estimated with high accuracy, even for complex, nonlinear relationships. Locally-Weighted Regression displays the best overall performance, which may be due to practical advantages in its training procedure. Moreover, accurate estimation can be achieved using only a modest amount of training data, as judged by convergence of performance. The algorithms are also applied to real-time MRI data, and the results are generally consistent with those obtained from synthetic data. PMID:24052685

Lammert, Adam; Goldstein, Louis; Narayanan, Shrikanth; Iskarous, Khalil

2012-01-01

302

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

303

Assessing stream aquifer interactions through inverse modeling of flow routing  

NASA Astrophysics Data System (ADS)

SummaryFlux-exchange between stream and aquifer is assessed on a 85.9 km stretch of the Danube River in Hungary. Streamflow is modeled with a spatially and temporally discretized version of the linear kinematic wave equation written in a state-space form which allows for an easy inversion of flow routing. By knowing in- and outflow of the reach, lateral flux exchange between stream and groundwater can be assessed. Continuous baseflow separation, in terms of groundwater gained by the river between the two gaging stations, is made possible at the downstream station by routing groundwater discharged to the stream reach, separately from streamflow measured at the upstream gaging station.

Szilagyi, Jozsef; Parlange, Marc B.; Balint, Gabor

2006-07-01

304

Parallel Inversion of Sparse Matrices  

Microsoft Academic Search

This paper presents a parallel algorithm for obtaining the inverse of a large, nonsingular symmetric matrix A of dimension nxn. The inversion method proposed is based on the triangular factors of A. The task of obtaining the \\

Ramon Betancourt; Fernando L. Alvarado

1986-01-01

305

Robust inversion for UXO discrimination  

E-print Network

1 Robust inversion for UXO discrimination Laurens Beran, Stephen Billings, Doug Oldenburg and discrimination performance Estimating standard deviations from the data is an important step for inversion of TEM discrimination. Lin Ping Song, Len Pasion, Nicolas Lhomme #12;

Oldenburg, Douglas W.

306

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

307

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

308

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

309

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

310

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

311

Silk inverse opals  

NASA Astrophysics Data System (ADS)

Periodic nanostructures provide the facility to control and manipulate the flow of light through their lattices. Three-dimensional photonic crystals enable the controlled design of structural colour, which can be varied by infiltrating the structure with different (typically liquid) fillers. Here, we report three-dimensional photonic crystals composed entirely of a purified natural protein (silk fibroin). The biocompatibility of this protein, as well as its favourable material properties and ease of biological functionalization, present opportunities for otherwise unattainable device applications such as bioresorbable integration of structural colour within living tissue or lattice functionalization by means of organic and inorganic material doping. We present a silk inverse opal that demonstrates a pseudo-photonic bandgap in the visible spectrum and show its associated structural colour beneath biological tissue. We also leverage silk's facile dopability to manufacture a gold nanoparticle silk inverse opal and demonstrate patterned heating mediated by enhancement of nanoparticle absorption at the band-edge frequency of the photonic crystal.

Kim, Sunghwan; Mitropoulos, Alexander N.; Spitzberg, Joshua D.; Tao, Hu; Kaplan, David L.; Omenetto, Fiorenzo G.

2012-12-01

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.

Exploratorium, The

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

Kinematic configuration analysis of planar mechanisms based on basic kinematic chains  

Microsoft Academic Search

According to the single-link transformation principle, and based on the topological characteristic investigations to planar closed kinematic chains (PCKCs), a general study of the kinematic configuration analysis of planar mechanisms with R-pairs is conducted in this paper. Firstly, two new concepts, contract link distance sequence and basic link group code sequence, are defined, and a novel approach for identification of

Songhui Nie; Bin Li; Aihong Qiu; Shuguang Gong

2011-01-01

315

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

316

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

317

Spitzer SAGE Followup: Kinematics of the LMC  

NASA Astrophysics Data System (ADS)

We propose to use the CTIO 4-m telescope and Hydra spectrograph to measure velocites for ~4500 LMC carbon stars and red supergiants (RSGs). Our pointings uniformly sample the entire H I disk of the LMC, covering significant area untouched by previous velocity surveys. These data will allow us to investigate a number of important issues concerning the LMC's kinematics. First, our recent analysis of existing carbon star velocities shows that ~10% of the carbon stars are tidally disturbed, the first instance in which stellar tidal streams drawn out of the LMC have been identified. Tracing these tidal streams in greater detail is critical for a clear understanding of the LMC's internal kinematics. Second, the dynamical centers derived from existing carbon star and H I gas observations differ by >1° on the sky, a discrepancy that may be due to perturbed kinematics in either the carbon stars or the H I, or both. Finally, all previous analyses of the LMC's kinematics have assumed that the LMC's stars and gas are on circular orbits. Our recent analysis indicates, however, that the LMC's disk is significantly lopsided, requiring predominantly eliptical orbits. We propose to investigate all of these issues with a large, uniformly sampled kinematic sample.

Olsen, Knut; Blum, Robert; Gordon, Karl; Harris, Jason; Meixner, Margaret; Oey, Sally; van Dyk, Schuyler; Zaritsky, Dennis

2007-08-01

318

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

319

Geometry and Kinematics of the High Zagros Belt (Iran)  

NASA Astrophysics Data System (ADS)

The High Zagros Belt (HZB) is the most internal part of the wider Zagros Fold-Thrust Belt (ZFTB). It is an elevated domain (up to 4400 m) bounded to the south by the High Zagros Fault (HZF), which we define as the southernmost principal thrust-fault carrying out Lower Paleozoic strata over Mesozoic or Cenozoic rocks. To the north the HZB is bounded either by the Main Zagros Thrust (MZT), which corresponds to the fundamental limit (Neo-Tethys suture) with the internal Sanandaj-Sirjan Zone (pertaining to the Eurasian Plate) or by the front of the discontinuous "Crush Zone" (CZ) in which are exposed rocks coming from the distal margin of the former Neo-Tethys Ocean. Following our definition the HZB, exists in two disconnected prominent and elevated domains: the Central and Eastern High Zagros (CHZB& EHZB) respectively. The CHZB is a funnel shape region with a length of about 450 Km and variable width between 40 to 80 Km broadening from the NW to the SE. We will present a new tectonic map of this region and four new balanced cross-sections with associated kinematic models. From a geometric point of view, we show the existence of an important intermediate décollement level located within Ordovician-Silurian shale. This décollement, together with the well-known Hormuz basal décollement, allows the development of duplexes confined at depth in the core of the anticlines. For the kinematics, we confirm a two-steps model with a first thin-skinned phase leading to the development of large detachment folds developed over the Hormuz salt layer. At this stage the different intermediate décollement levels were activated. The second phase is thick-skinned and corresponds to the inversion of deep-seated basement faults and occurrence oflarge out-of-sequence thrusts,responsible for the exhumation of Lower Paleozoic rocks. The Eastern High Zagros Belt is a more restricted area composed by three giant anticlines, namely the Gakhum, Faraghan and Kue-e-Khush anticlines. Here also, we will present a new tectonic map and balanced-sections crossing the three anticlines. From a geometric point of view, the most striking structure is a major back-thrust floored by Ordovician shale in the Faraghan anticline. We will show that this back-thrust developed during an early thin-skinned phase of deformation and is subsequently cut out by basement faults. Finally, we will present an integrated kinematic model for the whole HZB.

Tavakoli, S.; Frizon de lamotte, D.; Ringenbach, J.-C.; Ballard, J.-F.

2012-04-01

320

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

321

Viscoelastic modeling and inversion of a marine data set  

SciTech Connect

Deterministic waveform inversion in the p-{tau} domain permits estimation of the long-wavelength p-wave background velocity, the short-wavelength elastic parameter fluctuations, and the energy source for a marine data set from the Gulf of Mexico. The forward map is a convolutional model for p-wave primaries-only seismograms of viscoelastic, layered media. Two types of inversion (output least squares and differential semblance optimization) allow efficient estimation of various parameter combinations. Background velocities computed by differential semblance optimization were as consistent kinematically as those produced by interactive migration velocity analysis and gave somewhat more accurate depths. Source parameters obtained by output least squares inversion permitted considerably better fit to data than did those produced by as air gun modeling package. Output least squares inversion gave very short-scale detail of major reflectors closely resembling the detail derived from well logs. Despite evidence of considerable lateral heterogeneity in the shallow subsurface, estimates of deeper reflectors were remarkably consistent from midpoint to midpoint.

Minkoff, S.E.; Symes, W.W. [Rice Univ., Houston, TX (United States)

1994-12-31

322

Numerical algebraic geometry and algebraic kinematics  

NASA Astrophysics Data System (ADS)

In this article, the basic constructs of algebraic kinematics (links, joints, and mechanism spaces) are introduced. This provides a common schema for many kinds of problems that are of interest in kinematic studies. Once the problems are cast in this algebraic framework, they can be attacked by tools from algebraic geometry. In particular, we review the techniques of numerical algebraic geometry, which are primarily based on homotopy methods. We include a review of the main developments of recent years and outline some of the frontiers where further research is occurring. While numerical algebraic geometry applies broadly to any system of polynomial equations, algebraic kinematics provides a body of interesting examples for testing algorithms and for inspiring new avenues of work.

Wampler, Charles W.; Sommese, Andrew J.

323

Kinematic time migration and demigration of reflections in pre-stack seismic data  

NASA Astrophysics Data System (ADS)

In kinematic time migration one maps the time, slope and curvature characteristics of seismic reflection events, referred to as reflection-time parameters, from the recording domain of the seismic data to the time-migration domain. The inverse process is kinematic time demigration. We generalize kinematic time migration and demigration in several respects: the reflection-time parameters may belong to arbitrary source-receiver offsets; local heterogeneity of the time-migration velocity model is accounted for; the mapping operations do not depend specifically on the type of diffraction-time function and the parametrization of the velocity model. Time-migration and time-demigration spreading matrices are obtained as byproducts of the mapping operations. These matrices yield a paraxial expression for the connection between midpoint and image-point gather locations of mapped reflection events. Also, we obtain the time-migration counterpart of the so-called second duality theorem in Kirchhoff depth migration. Diffractions and reflections are assumed to be without conversion, and sources and receivers are located along the same measurement surface. Our framework enables the identification of a full set of first- and second-order reflection-time parameters from time-migrated seismic data followed by a kinematic demigration to the recording domain. The idea of this route is to 'undo' eventual errors introduced by time migration and result in reliable estimation of recording-domain invariants, that is, parameters insensitive to the time-migration velocity model. The developed concepts associated with time migration are of interest in reflection seismic and global earth applications. Two numerical examples demonstrate the potential of kinematic time migration and demigration techniques in seismic time imaging and velocity-model building.

Iversen, Einar; Tygel, Martin; Ursin, Bjørn; de Hoop, Maarten V.

2012-06-01

324

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.

325

Target Implantation for Inverse (^3He,d) Reaction Studies  

NASA Astrophysics Data System (ADS)

Proton transfer reactions such as (^3He,d) can provide valuable structure information on proton single particle states and resonances, some of which are very important for the rp process in explosive nucleosynthesis. In stellar explosions, the reactants are often radioactive, so radioactive ion beams and inverse kinematics are needed for such studies. These (^3He,d) experiments in inverse kinematics require localized ^3He targets. Since helium gas jet targets are difficult and expensive to produce, implanted targets may be the more practical solution. Helium implanted Al foil targets have been successfully produced in other facilitiesootnotetextJ. E. McDonald et al., Journal of Instr. 1, 09003 (2006). up to densities of ˜4x10^17 ions/cm^2. The UNISOR facility at the HRIBF at ORNL can be utilized to implant ^3He ions, but modifications to the UNISOR collection chamber are needed. A new assembly has been designed to accommodate a linear motion feedthrough that attaches to a target ladder on which aluminum foils and a slit for beam profile analysis can be mounted. The targets produced will be used in a number of experiments with stable and unstable beams. A detailed update of the project will be presented.

Sissom, D. J.; Kozub, R. L.; Bardayan, D. W.; Stracener, D. W.

2008-10-01

326

Identification of top quarks using kinematic variables  

NASA Astrophysics Data System (ADS)

We have used a kinematic technique to distinguish top quark pair production from background in pp¯ collisions at ?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 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 b jets. We interpret these results as evidence that most of the selected events are from tt¯ 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.-T.; 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.; 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.; Guillian, G.; Guo, R. S.; Haber, C.; Hahn, S. R.; Hamilton, R.; Handler, R.; Hans, R. M.; Hara, K.; Harral, B.; Harris, R. M.; Hauger, S. A.; Hauser, J.; Hawk, C.; Hayashi, E.; Heinrich, J.; Hohlmann, M.; Holck, C.; Hollebeek, R.; Holloway, L.; Ho, A.; Hong, S.; Houk, G.; Hu, P.; Huffman, B. T.; Hughes, R.; Huston, J.; Huth, J.; Hylen, J.; Ikeda, H.; Incagli, M.; Incandela, J.; Iwai, J.; Iwata, Y.; Jensen, H.; Joshi, U.; Kadel, R. W.; Kajfasz, E.; Kamon, T.; Kaneko, T.; Karr, K.; Kasha, H.; Kato, Y.; Keeble, L.; Kelley, K.; Kennedy, R. D.; Kephart, R.; Kesten, P.; Kestenbaum, D.; Keup, R. M.; Keutelian, H.; Keyvan, F.; Kim, B. J.; Kim, D. H.; Kim, H. S.; Kim, S. B.; Kim, S. H.; Kim, Y. K.; Kirsch, L.; Koehn, P.; Kondo, K.; Konigsberg, J.; Kopp, S.; Kordas, K.; Koska, W.; Kovacs, E.; Kowald, W.; Krasberg, M.; Kroll, J.; Kruse, M.; Kuwabara, T.; Kuhlmann, S. E.; Kuns, E.; Laasanen, A. T.; Labanca, N.; Lammel, S.; Lamoureux, J. I.; Lecompte, T.; Leone, S.; Lewis, J. D.; Limon, P.; Lindgren, M.; Liss, T. M.; Lockyer, N.; Long, O.; Loomis, C.; Loreti, M.; Lu, J.; Lucchesi, D.; Lukens, P.; Lusin, S.; Lys, J.; Maeshima, K.; Maghakian, A.; Maksimovic, P.; Mangano, M.; Mansour, J.; Mariotti, M.; Marriner, J. P.; Martin, A.; Matthews, J. A.; Mattingly, R.; McIntyre, P.; Melese, P.; Menzione, A.; Meschi, E.; Metzler, S.; Miao, C.; Michail, G.; Mikamo, S.; Miller, R.; Minato, H.; Miscetti, S.; Mishina, M.; Mitsushio, H.; Miyamoto, T.; Miyashita, S.; Morita, Y.; Mueller, J.; Mukherjee, A.; Muller, T.; Murat, P.; Nakada, H.; Nakano, I.; Nelson, C.; Neuberger, D.; Newman-Holmes, C.; Ninomiya, M.; Nodulman, L.; Ogawa, S.; Oh, S. H.; Ohl, K. E.; Ohmoto, T.; Ohsugi, T.; Oishi, R.; Okabe, M.; Okusawa, T.; Oliver, R.; Olsen, J.; Pagliarone, C.; Paoletti, R.; Papadimitriou, V.; Pappas, S. P.; Park, S.; Patrick, J.; Pauletta, G.; Paulini, M.; Pescara, L.; Peters, M. D.; Phillips, T. J.; Piacentino, G.; Pillai, M.; Pitts, K. T.; Plunkett, R.; Pondrom, L.; Proudfoot, J.; Ptohos, F.; Punzi, G.; Ragan, K.; Ribon, A.; Rimondi, F.; Ristori, L.; Robertson, W. J.; Rodrigo, T.; Romano, J.; Rosenson, L.; Roser, R.; Sakumoto, W. K.; Saltzberg, D.; Santi, L.; Sato, H.; Scarpine, V.; Schlabach, P.; Schmidt, E. E.; Schmidt, M. P.; Sciacca, G. F.; Scribano, A.; Segler, S.; Seidel, S.; Seiya, Y.; Sganos, G.; Sgolacchia, A.; Shapiro, M. D.; Shaw, N. M.; Shen, Q.; Shepard, P. F.; Shimojima, M.; Shochet, M.; Siegrist, J.; Sill, A.; Sinervo, P.; Singh, P.; Skarha, J.; Sliwa, K.; Smith, D. A.; Snider, F. D.; Song, T.; Spalding, J.; Sphicas, P.; Spiegel, L.; Spies, A.; Stanco, L.; Steele, J.; Stefanini, A.; Strahl, K.; Strait, J.; Stuart, D.; Sullivan, G.; Soumarokov, A.; Sumorok, K.; Suzuki, J.; Takada, T.; Takahashi, T.; Takano, T.; Takikawa, K.; Tamura, N.; Tartarelli, F.; Taylor, W.; Teng, P. K.

1995-09-01

327

Kinematics of the symbiotic system R Aqr  

NASA Astrophysics Data System (ADS)

We present the results of the kinematical analysis of the symbiotic system R Aqr. We obtained high dispersion spectra with the MES spectrograph at the 2.1 m telescope of San Pedro Mártir (MEZCAL). The used filter were Ha + [NII], (?c = 6575Å, ?? = 90Å). We analyse the [NII] ??6583 line. When the observations are compared with previous ones by Solf (1992) we detected an important change in the projected velocities of the observed knots, supporting the idea of a precessing jet. We are working also in a 3-D kinematic model for the object using the measured velocities and the state of the model is presented.

Navarro, S.; Corral, L. J.; Steffen, W.

2014-04-01

328

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

329

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

330

Source Inversion Validation: Quantifying Uncertainties in Earthquake Source Inversions  

Microsoft Academic Search

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

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

2010-01-01

331

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

332

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

333

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

334

IDENTIFICATION OF ISOMORPHISM AMONG KINEMATIC CHAINS AND INVERSIONS USING LINK ADJACENCY VALUES  

Microsoft Academic Search

The present work deals with problem of detection of isomorphism which is frequently encountered in structural synthesis of kimematic chains. Using the link adjacency values a new method has been proposed to reveal simultaneously chain is isomorphic and link is isomorphic. Two new invariants for each link, called as first adjacency link value (FALV) and second adjacency link value (SALV)

Ashok Dargar; Ali Hasan; R. A. Khan

2009-01-01

335

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

336

Mechanical constraints on inversion of co-seismic geodetic data for fault slip and geometry  

Microsoft Academic Search

Modern geodetic techniques, such as the Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR), provide high-precision deformation measurements of earthquakes. Through elastic models and mathematical optimization methods, the observations can be related to a slip-distribution model. The classic linear, kinematic, and static slip inversion problem requires specification of a smoothing norm of slip parameters and a residual norm

F. Liang; J. Sun; K. M. Johnson; Z. Shen; R. Burgmann

2010-01-01

337

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

338

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

339

Kinematic Distance Assignments with H I Absorption  

NASA Astrophysics Data System (ADS)

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.

2012-07-01

340

Three-dimensional kinematics of hummingbird flight  

Microsoft Academic Search

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

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

2007-01-01

341

On the Forward Kinematics of Parallel Manipulators  

Microsoft Academic Search

In this article we present a novel procedure for the system atic analysis of the forward kinematics of a class of parallel manipulators that generalize the well-known Stewart plat form. The designs comprise a movable platform connected to a fixed base by a set of legs, the lengths of which can be con trolled. The legs are connected to the

R. Nair; J. H. Maddocks

1994-01-01

342

Circadian rhythms in handwriting kinematics and legibility  

Microsoft Academic Search

The aim of the present study was to analyze the circadian rhythmicity in handwriting kinematics and legibility and to compare the performance between Dutch and German writers. Two subject groups underwent a 40h sleep deprivation protocol under Constant Routine conditions either in Groningen (10 Dutch subjects) or in Berlin (9 German subjects). Both groups wrote every 3h a test sentence

Isabelle Jasper; Marijke Gordijn; Andreas Häußler; Joachim Hermsdörfer

2011-01-01

343

Compound nucleus studies withy reverse kinematics  

SciTech Connect

Reverse kinematics reactions are used to demonstrate the compound nucleus origin of intermediate mass particles at low energies and the extension of the same mechanism at higher energies. No evidence has appeared in our energy range for liquid-vapor equilibrium or cold fragmentation mechanisms. 11 refs., 12 figs.

Moretto, L.G.

1985-06-01

344

Lower extremity kinematics of athletics curve sprinting.  

PubMed

Abstract Curve running requires the generation of centripetal force altering the movement pattern in comparison to the straight path run. The question arises which kinematic modulations emerge while bend sprinting at high velocities. It has been suggested that during curve sprints the legs fulfil different functions. A three-dimensional motion analysis (16 high-speed cameras) was conducted to compare the segmental kinematics of the lower extremity during the stance phases of linear and curve sprints (radius: 36.5 m) of six sprinters of national competitive level. Peak joint angles substantially differed in the frontal and transversal plane whereas sagittal plane kinematics remained unchanged. During the prolonged left stance phase (left: 107.5 ms, right: 95.7 ms, straight: 104.4 ms) the maximum values of ankle eversion (left: 12.7°, right: 2.6°, straight: 6.6°), hip adduction (left: 13.8°, right: 5.5°, straight: 8.8°) and hip external rotation (left: 21.6°, right: 12.9°, straight: 16.7°) were significantly higher. The inside leg seemed to stabilise the movement in the frontal plane (eversion-adduction strategy) whereas the outside leg provided and controlled the motion in the horizontal plane (rotation strategy). These results extend the principal understanding of the effects of curve sprinting on lower extremity kinematics. This helps to increase the understanding of nonlinear human bipedal locomotion, which in turn might lead to improvements in athletic performance and injury prevention. PMID:25495196

Alt, Tobias; Heinrich, Kai; Funken, Johannes; Potthast, Wolfgang

2015-03-01

345

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

346

Chemical tagging of stellar kinematic groups  

NASA Astrophysics Data System (ADS)

Stellar Kinematic Groups are kinematical coherent groups of stars which might share a common origin. These groups spread through the Galaxy over time due to tidal effects caused by galactic rotation and disc heating, however the chemical information survives. The aim of chemical tagging is to show that abundances of every chemical element must be homogeneus among candidate members. We have studied the case of the Hyades Supercluster and the Ursa Major Moving Group for kinematically selected FGK stars, based on high-resolution spectroscopic observations obtained at the 1.2 m Mercator Telescope with the HERMES Spectrograph. Stellar atmospheric parameters (T_{eff}, log{g}, ? and [Fe/H]) have been determined using an own-implemented automatic code (StePar) which makes use of the sensibility from iron EWs measured in the spectra. We have derived the chemical abundances of several elements and their [X/Fe] ratios. Thus, we finally perform a careful differential abundance analysis using a known member of each cluster as a reference star, with the aim to clarify the origin of these kinematical groups.

Tabernero, H. M.; Montes, D.; González Hernández, J. I.

2013-05-01

347

Expertise and attunement to kinematic constraints.  

PubMed

Three experiments were undertaken to ascertain the extent to which expertise in natural anticipatory tasks is characterised by superior attunement to the biomechanical (kinematic) constraints of the movement pattern being observed. Twelve world-class and twelve non-expert badminton players were required to predict the depth of an opponent's stroke from either video displays or point-light displays of the opposing player's hitting action. The information available within the displays was manipulated through temporal and/or spatial occlusion. Consistent with predictions that can be derived from the constraint-attunement hypothesis (Vicente and Wang, 1998 Psychological Review 105 33-57), experts showed: (i) an unchanged pattern of information pick-up when the display was reduced from video to point-light and only kinematic information was available; (ii) superior information pick-up from kinematic features that non-experts could use; and (iii) attunement to early kinematic information from the lower body to which non-experts were not sensitive. Consistent with predictions that can be derived from a common-coding perspective (Prinz, 1997 European Journal of Cognitive Psychology 9 129-154), the anticipation of stroke depth was facilitated more for experts than non-experts when the perceptual display provided linked segment information reminiscent of the cross-segmental torque transfers that occur during expert movement production. PMID:18686711

Abernethy, Bruce; Zawi, Khairi; Jackson, Robin C

2008-01-01

348

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

349

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

350

Stellar Archeology : Chemical Compositions and Kinematics  

NASA Astrophysics Data System (ADS)

The ?-CDM model of cosmology predicts a hierarchical formation mechanism of galaxies, with smaller units accreting to construct larger ones. The detection of merger events in external galaxies is well known, and the detection and analysis of merger remnants in the Milky Way is a key component in piecing together the history of our home galaxy. Statistical analyses of stellar kinematics in the solar neighborhood reveal much kinematic structure in the Galactic disk, but it is not readily apparent whether this structure is extragalactic or dynamical in origin. The most prominent structures are quickly identified as well known moving groups of stars such as the Hercules, Sirius, and Hyades stellar streams. Additionally, a subset of kinematically selected stars observed at McDonald Observatory are members of a stellar stream putatively identified by Amina Helmi as part of a merger remnant. A semi-automated, high resolution spectral analysis is applied to 504 F and G dwarf stars, and the results are amenable to Kolmogorov-Smirnov membership hypothesis testing. In all four cases, the kinematic streams have chemistries roughly consistent with the Galactic disk trends, although the statistical analyses suggest some subtle differences.

Stringer, Bayard; Carney, Bruce

2011-10-01

351

ANALYTIC MODELING OF THE MORETON WAVE KINEMATICS  

SciTech Connect

The issue whether Moreton waves are flare-ignited or coronal mass ejection (CME)-driven, or a combination of both, is still a matter of debate. We develop an analytical model describing the evolution of a large-amplitude coronal wave emitted by the expansion of a circular source surface in order to mimic the evolution of a Moreton wave. The model results are confronted with observations of a strong Moreton wave observed in association with the X3.8/3B flare/CME event from 2005 January 17. Using different input parameters for the expansion of the source region, either derived from the real CME observations (assuming that the upward moving CME drives the wave), or synthetically generated scenarios (expanding flare region, lateral expansion of the CME flanks), we calculate the kinematics of the associated Moreton wave signature. Those model input parameters are determined which fit the observed Moreton wave kinematics best. Using the measured kinematics of the upward moving CME as the model input, we are not able to reproduce the observed Moreton wave kinematics. The observations of the Moreton wave can be reproduced only by applying a strong and impulsive acceleration for the source region expansion acting in a piston mechanism scenario. Based on these results we propose that the expansion of the flaring region or the lateral expansion of the CME flanks is more likely the driver of the Moreton wave than the upward moving CME front.

Temmer, M.; Veronig, A. M. [IGAM/Kanzelhoehe Observatory, Institute of Physics, Universitaet Graz, Universitaetsplatz 5, A-8010 Graz (Austria); Vrsnak, B.; Zic, T. [Hvar Observatory, Faculty of Geodesy, University of Zagreb, Kaciceva 26, HR-10000 (Croatia)], E-mail: mat@igam.uni-graz.at

2009-09-10

352

SOLVING THE BURMESTER PROBLEM USING KINEMATIC MAPPING  

Microsoft Academic Search

Planar kinematic mapping is applied to the five-position Burmester problem for planar four-bar mechanism synthesis. The problem formulation takes the five distinct rigid body poses directly as inputs to generate five quadratic constraint equations. The five poses are on the fourth order curve of intersection of two hyperboloids of one sheet in the image space. Moreover, the five poses uniquely

M. J. D. Hayes; P. J. Zsombor-Murray

2002-01-01

353

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

354

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

355

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

356

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

357

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

358

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

359

CUSP Kinematic Model Development Lucia Martinez M. John D. Hayes  

E-print Network

the future path of the CUSP kinematic model development. 2. Planar Parallel 3-RPR Manipulator In order to study different kinematic models, a simple planar parallel manipulator was chosen. Choosing a planar methods were selected to analyse the kinematics of the planar parallel 3-RPR manipulator: the first uses

Hayes, John

360

A robust forward kinematics analysis of 3-RPR planar platforms  

E-print Network

A robust forward kinematics analysis of 3-RPR planar platforms Nicol´as Rojas and Federico Thomas}@iri.upc.edu Abstract. The standard forward kinematics analysis of 3-RPR planar parallel platforms boils down this inconvenience by trans- lating the forward kinematics problem to be solved into an equivalent problem fully

361

KINEMATICS, STATICS, AND DEXTERITY OF PLANAR ACTIVE STRUCTURE MODULES  

E-print Network

1 KINEMATICS, STATICS, AND DEXTERITY OF PLANAR ACTIVE STRUCTURE MODULES Robert L. Williams II Rex J@bobcat.ent.ohiou.edu #12;2 KINEMATICS, STATICS, AND DEXTERITY OF PLANAR ACTIVE STRUCTURE MODULES Robert L. Williams II Rex, integrated, optimized design. This article presents a first step for integrated kinematic, static, dynamic

Williams II, Robert L.

362

Direct Kinematic Mapping for General Planar Parallel Manipulators  

E-print Network

Direct Kinematic Mapping for General Planar Parallel Manipulators P.J. Zsombor-Murray Dept Abstract: Planar kinematic mapping yields a highly compact general symbolic uni- variate polynomial manipula- tors. Direct kinematics solutions of planar parallel robots with arbitrary mixed leg ar

Hayes, John

363

Kinematic and dynamic analysis of mechanisms, a finite element approach  

Microsoft Academic Search

The development of the finite element method for the numerical analysis of the mechanical behaviour of structures has been directed at the calculation of the state of deformation and stress of kinematically determinate structures. The discretized description of the kinematics of kinematically indeterminate structures as given in the finite element method is however also a good starting point for the

K. Van der Werff

1977-01-01

364

Acknowledgements KINEMATICS OF VARIOUS SWIMMING MODES IN ANTARCTIC KRILL  

E-print Network

pleopod kinematics to sensory mechanisms and fluid dynamics Upside Down Swimming Hovering Fast Forward analysis Kinematics Analysis ·Krill hovering at air-water interface ·One complete beat cycle shown ·Frames Kinematics Analysis ·Support provided by NSF East Asia ­ Pacific Summer Institute 2008 ·The authors thank

365

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

PubMed

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

366

Effects of different unstable sole construction on kinematics and muscle activity of lower limb.  

PubMed

Unstable sole construction can change biomechanics of lower extremity as highlighted by some previous studies, which could potentially help developing special training or rehabilitation schemes. In this study, unstable elements are fixed in heel and forefoot zone to exert unstable perturbations, and the position changes (medial, neutral and lateral) of unstable elements in forefoot coronal plane are adjusted to analyze changes of lower extremity kinematics and muscle activities. Twenty-two healthy male subjects participated in the test, walking with control shoes and experimental shoes randomly under self-selected speed. Kinematics and surface electromyography measurements were carried out simultaneously. It is found that experimental shoes can lead to the reduction of knee abduction and internal rotation and hip internal rotation, with p<.05. Ankle inversion and internal rotation amplitude were also reduced, which are associated with significantly increased activation levels of muscles (TA-tibialis anterior, PL-peroneus longus, LG-lateral gastrocnemius) in order to compensate perturbations. It is suggested that a training equipment incorporating unstable elements would enhance postural control by adjusting lower extremity kinematics and reorganizing muscle activity. More research can be conducted to testify the feasibility of unstable shoes construction on human postural control and gait, even guide training regime design, injury prevention and rehabilitation. PMID:24929612

Gu, Yaodong; Lu, Yong; Mei, Qichang; Li, Jianshe; Ren, James

2014-08-01

367

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

368

Global analysis of linearized inversion for the acoustic wave equation  

NASA Astrophysics Data System (ADS)

To predict the location of natural resources and reduce the cost of exploration, geophysicists rely on various techniques to map the internal structure of the earth. One common mapping method probes the earth's interior using an acoustic energy source (sound waves). The acoustic waves reflect when they impinge on a location where the acoustic velocity field oscillates rapidly (on the scale of a wavelength). When the waves reflect back to the surface, they carry kinematical information about the location of the oscillatory velocity field. A linearized wave equation models the scattering process and its solution operator is a Fourier integral operator. As such, the scattering operator has a canonical relation ? which describes how the operator maps oscillatory velocity fields to oscillatory wave fields at the surface. The goal of linearized inversion is to obtain an inverse operator (with inverse canonical relation) for the scattering operator. We give a geometrical condition on ? that is equivalent to the existence of a linearized inversion operator. Since the L2-adjoint of the scattering operator has inverse canonical relation, geophysicists often apply it to the scattered field to obtain a map of the subsurface. I analyze the scattering operator using high-frequency asymptotics and show that if the geometrical condition fails, the scattering canonical relation is not injective. Therefore, application of the adjoint operator to the scattered wave field can produce artifacts in the resulting map of the subsurface. I demonstrate this effect numerically. I also prove that the scattering operator is continuous between a certain domain and range space iff the geometrical condition on ? holds. Furthermore, I have shown that it is possible to map an experiment where the geometrical condition fails into another experiment where it holds.

Nolan, Clifford Joseph

1997-09-01

369

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

370

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

371

A classification of finite quantum kinematics  

NASA Astrophysics Data System (ADS)

Quantum mechanics in Hilbert spaces of finite dimension N is reviewed from the number theoretic point of view. For composite numbers N possible quantum kinematics are classified on the basis of Mackey's Imprimitivity Theorem for finite Abelian groups. This yields also a classification of finite Weyl-Heisenberg groups and the corresponding finite quantum kinematics. Simple number theory gets involved through the fundamental theorem describing all finite discrete Abelian groups of order N as direct products of cyclic groups, whose orders are powers of not necessarily distinct primes contained in the prime decomposition of N. The representation theoretic approach is further compared with the algebraic approach, where the basic object is the corresponding operator algebra. The consideration of fine gradings of this associative algebra then brings a fresh look on the relation between the mathematical formalism and physical realizations of finite quantum systems.

Tolar, J.

2014-10-01

372

Kinematics of tt¯ events at CDF  

NASA Astrophysics Data System (ADS)

The kinematic properties of tt¯ events are studied in the W+multijet channel using data collected with the CDF detector during the 1992-1995 runs at the Fermilab Tevatron collider corresponding to an integrated luminosity of 109 pb-1. Distributions of a variety of kinematic variables chosen to be sensitive to different aspects of tt¯ production are compared with those expected from Monte Carlo calculations. A sample of 34 events rich in tt¯ pairs is obtained by requiring at least one jet identified by the silicon vertex detector (SVX) as having a displaced vertex consistent with the decay of a b hadron. The data are found to be in good agreement with predictions of the leading order tt¯ matrix element with color coherent parton shower evolution.

Abe, F.; Akimoto, H.; Akopian, A.; Albrow, M. G.; Amadon, A.; Amendolia, S. R.; Amidei, D.; Antos, J.; Aota, S.; Apollinari, G.; Arisawa, T.; Asakawa, T.; Ashmanskas, W.; Atac, M.; Azzi-Bacchetta, P.; Bacchetta, N.; Bagdasarov, S.; Bailey, M. W.; de Barbaro, P.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barone, M.; Bauer, G.; Baumann, T.; Bedeschi, F.; Behrends, S.; Belforte, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Bensinger, J.; Beretvas, A.; Berge, J. P.; Berryhill, J.; Bertolucci, S.; Bettelli, S.; Bevensee, B.; Bhatti, A.; Biery, K.; Bigongiari, C.; Binkley, M.; Bisello, D.; Blair, R. E.; Blocker, C.; Bloom, K.; Blusk, S.; Bodek, A.; Bikhari, W.; Bolla, G.; Bonushkin, Y.; Bortoletto, D.; Boudreau, J.; Breccia, L.; Bromberg, C.; Bruner, N.; Brunetti, R.; Buckley-Geer, E.; Budd, H. S.; Burkett, K.; Busetto, G.; Byon-Wagner, A.; Byrum, K. L.; Campbell, M.; Caner, A.; Carithers, W.; Carlsmith, D.; Cassada, J.; Castro, A.; Cauz, D.; Cerri, A.; Chang, P. S.; Chang, P. T.; Chao, H. Y.; Chapman, J.; Cheng, M.-T.; Chertok, M.; Chiarelli, G.; Chiou, C. N.; Chlebana, F.; Christofek, L.; Cropp, R.; Chu, M. L.; Cihangir, S.; Clark, A. G.; Cobal, M.; Cocca, E.; Contreras, M.; Conway, J.; Cooper, J.; Cordelli, M.; Costanzo, D.; Couyoumtzelis, C.; Cronin-Hennessy, D.; Culbertson, R.; Dagenhart, D.; Daniels, T.; Dejongh, F.; dell'agnello, S.; dell'orso, M.; Demina, R.; Demortier, L.; Deninno, M.; Derwent, P. F.; Devlin, T.; Dittmann, J. R.; Donati, S.; Done, J.; Dorigo, T.; Eddy, N.; Einsweiler, K.; Elias, J. E.; Ely, R.; Engels, E.; Erdmann, W.; Errede, D.; Errede, S.; Fan, Q.; Feild, R. G.; Feng, Z.; Ferretti, C.; Fiori, I.; Flaugher, B.; Foster, G. W.; Franklin, M.; Freeman, J.; Friedman, J.; Frisch, H.; Fukui, Y.; Gadomski, S.; Galeotti, S.; Gallinaro, M.; Ganel, O.; Garcia-Sciveres, M.; Garfinkel, A. F.; Gay, C.; Geer, S.; Gerdes, D. W.; Giannetti, P.; Giokaris, N.; Giromini, P.; Giusti, G.; Gold, M.; Gordon, A.; Goshaw, A. T.; Gotra, Y.; Goulianos, K.; Grassmann, H.; Green, C.; Groer, L.; Grosso-Pilcher, C.; Guillian, G.; Guimaraes da Costa, J.; Guo, R. S.; Haber, C.; Hafen, E.; Hahn, S. R.; Hamilton, R.; Handa, T.; Handler, R.; Hao, W.; Happacher, F.; Hara, K.; Hardman, A. D.; Harris, R. M.; Hartmann, F.; Hausser, J.; Hayashi, E.; Heinrich, J.; Heiss, A.; Hinrichsen, B.; Hoffman, K. D.; Holck, C.; Hollebeek, R.; Holloway, L.; Huang, Z.; Huffman, B. T.; Hughes, R.; Huston, J.; Huth, J.; Ikeda, H.; Incagli, M.; Incandela, J.; Introzzi, G.; Iwai, J.; Iwata, Y.; James, E.; Jensen, H.; Joshi, U.; Kajfasz, E.; Kambara, H.; Kamon, T.; Kaneko, T.; Karr, K.; Kasha, H.; Kato, Y.; Keaffaber, T. A.; Kelley, K.; Kennedy, R. D.; Kephart, R.; Kestenbaum, D.; Khazins, D.; Kikuchi, T.; Kim, B. J.; Kim, H. S.; Kim, S. H.; Kim, Y. K.; Kirsch, L.; Klimenko, S.; Knoblauch, D.; Koehn, P.; Köngeter, A.; Kondo, K.; Konigsberg, J.; Kordas, K.; Korytov, A.; Kovacs, E.; Kowald, W.; Kroll, J.; Kruse, M.; Kuhlmann, S. E.; Kuns, E.; Kurino, K.; Kuwabara, T.; Laasanen, A. T.; Lami, S.; Lammel, S.; Lamoureux, J. I.; Lancaster, M.; Lanzoni, M.; Latino, G.; Lecompte, T.; Leone, S.; Lewis, J. D.; Lindgren, M.; Liss, T. M.; Liu, J. B.; Liu, Y. C.; Lockyer, N.; Long, O.; Loreti, M.; Lucchesi, D.; Lukens, P.; Lusin, S.; Lys, J.; Maeshima, K.; Maksimovic, P.; Mangano, M.; Mariotti, M.; Marriner, J. P.; Martignon, G.; Martin, A.; Matthews, J. A.; Mazzanti, P.; McFarland, K.; McIntyre, P.; Melese, P.; Menguzzato, M.; Menzione, A.; Meschi, E.; Metzler, S.; Miao, C.; Miao, T.; Michail, G.; Miller, R.; Minato, H.; Miscetti, S.; Mishina, M.; Miyashita, S.; Moggi, N.; Moore, E.; Morita, Y.; Mukherjee, A.; Muller, T.; Munar, A.; Murat, P.; Murgia, S.; Musy, M.; Nakada, H.; Nakaya, T.; Nakano, I.; Nelson, C.; Neuberger, D.; Newman-Holmes, C.; Ngan, C.-Y. P.; Nodulman, L.; Nomerotski, A.; Oh, S. H.; Ohmoto, T.; Ohsugi, T.; Oishi, R.; Okabe, M.; Okusawa, T.; Olsen, J.; Pagliarone, C.; Paoletti, R.; Papadimitriou, V.; Pappas, S. P.; Parashar, N.; Parri, A.; Patrick, J.; Pauletta, G.; Paulini, M.; Perazzo, A.; Pescara, L.; Peters, M. D.; Phillips, T. J.; Piacentino, G.; Pillai, M.; Pitts, K. T.; Plunkett, R.; Pompos, A.; Pondrom, L.; Proudfoot, J.; Ptohos, F.; Punzi, G.; Ragan, K.; Reher, D.; Reischl, M.; Ribon, A.; Rimondi, F.; Ristori, L.; Robertson, W. J.; Robinson, A.; Rodrigo, T.; Rolli, S.; Rosenson, L.; Roser, R.; Saab, T.; Sakumoto, W. K.; Saltzberg, D.; Sansoni, A.; Santi, L.; Sato, H.; Schlabach, P.; Schmidt, E. E.; Schmidt, M. P.; Scott, A.; Scribano, A.; Segler, S.; Seidel, S.; Seiya, Y.; Semeria, F.; Shah, T.; Shapiro, M. D.; Shaw, N. M.; Shepard, P. F.; Shibayama, T.; Shimojima, M.; Shochet, M.; Siegrist, J.; Sill, A.; Sinervo, P.; Singh, P.; Sliwa, K.; Smith, C.; Snider, F. D.; Spalding, J.; Speer, T.; Sphicas, P.; Spinella, F.; Spiropulu, M.

1999-05-01

373

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

374

Kinematics of swimming garter snakes (Thamnophis sirtalis).  

PubMed

We investigate the kinematics of swimming garter snakes (Thamnophis sirtalis) using a novel nonlinear regression-based digitization method to establish quantitative statistical support for non-constant wavelengths in the undulatory pattern exhibited by swimming snakes. We find that in swimming snakes, the growth of the amplitude of the propulsive wave head-to-tail is strongly correlated (p < 0.005) with the head-to-tail growth in the wavelength. We investigate correlations between kinematic parameters and steady swimming speed, and find a very strong positive correlation between swimming speed and undulation frequency. We furthermore find a statistically well-supported positive correlation between swimming speed and both the initial amplitude of the propulsive wave at the head and the degree of amplitude growth from head to tail. PMID:17950016

Munk, Yonatan

2008-06-01

375

Kinematic structures in galactic disc simulations  

NASA Astrophysics Data System (ADS)

N-body and test particle simulations have been used to characterize the stellar streams in the galactic discs of Milky Way type galaxies. Tools such as the second and third order moments of the velocity ellipsoid and clustering methods -EM-WEKA and FoF- allow characterizing these kinematic structures and linking them to the stellar overdensities and to the resonant regions all through the disc.

Roca-Fàbrega, S.; Romero-Gómez, M.; Figueras, F.; Antoja, T.; Valenzuela, O.

2011-10-01

376

Kinematics of superdense galaxies in clusters  

NASA Astrophysics Data System (ADS)

We present the first results obtained by analyzing the detailed kinematics of a subsample of 9 massive and compact galaxies found in the WINGS survey. The observed galaxies are very old (both luminosity and mass- weighted age are on average >= 10 Gyr), while they resemble more typical galaxies in the other characteristics. The total M/L ratio is determined using as free parameters the anisotropy ? and the galaxy inclination i.

Moretti, Alessia; Poggianti, Bianca; Bettoni, Daniela; Cappellari, Michele; Fasano, Giovanni

2015-02-01

377

First-Order Ball-Bearing Kinematics  

Microsoft Academic Search

Two first-order equations are given connecting geometry and internal motions in an angular-contact ball bearing. Total speed, kinematic equivalence, basic speed ratio, and modal speed ratio are defined and discussed; charts are given for the speed ratios covering all bearings and all rotational modes. Instances where specific first-order assumptions might fail are discussed, and the resulting effects on bearing performance

Edward Kingsbury

1985-01-01

378

First-order ball-bearing kinematics  

NASA Technical Reports Server (NTRS)

Two first-order equations are given connecting geometry and internal motions in an angular-contact ball bearing. Total speed, kinematic equivalence, basic speed ratio, and modal speed ratio are defined and discussed; charts are given for the speed ratios covering all bearings and all rotational modes. Instances where specific first-order assumptions might fail are discussed, and the resulting effects on bearing performance reviewed.

Kingsbury, E.

1985-01-01

379

Gravito-magnetic vacuum spacetimes: kinematic restrictions  

E-print Network

We show that there are no vacuum solutions with a purely magnetic Weyl tensor with respect to an observer submitted to kinematic restrictions involving first order differential scalars. This result generalizes previous ones for the vorticity-free and shear-free cases. We use a covariant approach which makes evident that only the Bianchi identities are used and, consequently, the results are also valid for non vacuum solutions with vanishing Cotton tensor.

J. J. Ferrando; J. A. Saez

2003-03-12

380

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

381

The kinematic component of the cosmological redshift  

E-print Network

It is widely believed that the cosmological redshift is not a Doppler shift. However, Bunn & Hogg have recently pointed out that to settle properly this problem, one has to transport parallelly the velocity four-vector of a distant galaxy to the observer's position. Performing such a transport along the null geodesic of photons arriving from the galaxy, they found that the cosmological redshift is purely kinematic. Here we argue that one should rather transport the velocity four-vector along the geodesic connecting the points of intersection of the world-lines of the galaxy and the observer with the hypersurface of constant cosmic time. We find that the resulting relation between the transported velocity and the redshift of arriving photons is not given by a relativistic Doppler formula. Instead, for small redshifts it coincides with the well known non-relativistic decomposition of the redshift into a Doppler (kinematic) component and a gravitational one. We perform such a decomposition for arbitrary large redshifts and derive a formula for the kinematic component of the cosmological redshift, valid for any FLRW cosmology. In particular, in a universe with Omega_m = 0.24 and Omega_Lambda = 0.76, a quasar at a redshift 6, at the time of emission of photons reaching us today had the recession velocity v = 0.997c. This can be contrasted with v = 0.96c, had the redshift been entirely kinematic. Thus, for recession velocities of such high-redshift sources, the effect of deceleration of the early Universe clearly prevails over the effect of its relatively recent acceleration. Last but not least, we show that the so-called proper recession velocities of galaxies, commonly used in cosmology, are in fact radial components of the galaxies' four-velocity vectors. As such, they can indeed attain superluminal values, but should not be regarded as real velocities.

Micha? Chodorowski

2011-03-08

382

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

383

The galactic kinematics of Mira variables  

NASA Astrophysics Data System (ADS)

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 145-200 day 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.

Feast, Michael

2003-04-01

384

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

385

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

386

Parallelism in planar kinematic chains (manipulators)  

Microsoft Academic Search

Parallelism is an important characteristic of closed kinematic chains particularly for chains with degrees-of-freedom (d.o.f.) greater than one since such chains can be considered for application as robot manipulators. For specified number of links and d.o.f. there exists a large number of distinct chains and hence the designer should have a clue to select the best possible chain for the

A. C. Rao

2004-01-01

387

Computational tool for comparison of kinematic mechanisms and commonly used kinematic models  

SciTech Connect

Accurate, reliable, and reproducible methods to measure the movements of human joints have been elusive. Currently, three-dimensional recording methods are used to track the motion of one segment relative to another as the joint moves. Six parameters describe the moving segment`s location and orientation relative to the reference segment: three translations (x, y, and z) and three rotations (yaw, pitch and roll) in the reference frame. The raw data can be difficult to interpret. For this reason, several methods have been developed to measure the motion of human joints and to describe the resulting data. For example, instant helical axes or screw deviation axes (Kinzell et al., 1972), the Joint Coordinate System of Grood and Suntay (1983), and the Euler angle method have been used to describe the movements of bones relative to each other. None of these methods takes into account the physical kinematic mechanism producing the joint motion. More recently, Lupichuk (1995) has developed an algorithm to find, for an arbitrary revolute, the axis` position and orientation in three- dimensional space. Each of these methods has advantages and disadvantages in analyzing joint kinematics. The authors have developed software to provide a means of comparing these methods for arbitrary, single degree of freedom, kinematic mechanisms. Our objective is to demonstrate the software and to show how it can be used to compare the results from the different kinematic models as they are applied to specific kinematic mechanisms.

Hollerbach, K.; Hollister, A.M.; Van Vorhis, R.L.

1997-03-01

388

Inversion of snow parameters by neural network with iterative inversion  

NASA Technical Reports Server (NTRS)

The inversion of snow parameters from passive microwave remote sensing measurements is performed with a neural network trained with a dense media multiple scattering model. A constrained iterative inversion scheme is used. Inversion of four parameters is performed from five brightness temperatures. The four parameters are: mean grain size of ice particles in snow, snow density, snow temperature, and snow depth. The five brightness temperatures are that of 19-GHz vertical polarization, 19-GHz horizontal polarization, 22-GHz vertical polarization, 37-GHz vertical polarization, and 37-GHz horizontal polarization. Based on the neural network constrained iterative inversion algorithm, synthetic mapping of the terrain is performed. The retrieval of synthetic mapping has been achieved. The incorporation of ground truth information is considered.

Chen, Zhengxiao; Davis, Daniel; Tsang, Leung; Hwang, Jenq-Neng; Chang, A. T. C.

1992-01-01

389

Givental graphs and inversion symmetry  

E-print Network

Inversion symmetry is a very non-trivial discrete symmetry of Frobenius manifolds. It was obtained by Dubrovin from one of the elementary Schlesinger transformations of a special ODE associated to a Frobenius manifold. In this paper, we review the Givental group action on Frobenius manifolds in terms of Feynman graphs and obtain an interpretation of the inversion symmetry in terms of the action of the Givental group. We also consider the implication of this interpretation of the inversion symmetry for the Schlesinger transformations and for the Hamiltonians of the associated principle hierarchy.

P. Dunin-Barkowski; S. Shadrin; L. Spitz

2012-12-17

390

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

391

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

392

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

393

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

394

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

395

Donor states in inverse opals  

NASA Astrophysics Data System (ADS)

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.

2014-09-01

396

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

397

Molecular Kinematics Tracers in Bright-Rimmed Cloud SFO14  

NASA Astrophysics Data System (ADS)

The star cluster AFGL4029 and associated nebulosity IC1848 (herein referred to as bright-rimmed cloud SFO14) has been forwarded by numerous studies as an example of small-scale sequential star formation (S4F), in which star formation proceeds across a region as the result of triggering mechanisms such as Collect-and-Collapse and Radiative Driven Implosion (RDI). We would like to develop a detailed picture of the molecular dynamical interactions within SFO14 (and other regions where RDI may be responsible for star formation) in order to see if the dynamics within the cloud can be linked to the conditions in the HII region beyond the rim. We present multi-wavelength observations of the bright-rimmed cloud SFO14 in NH3(1,1) and (2,2) inversion transitions and 12CO, 13CO, and C18O (J=3->2) transitions. These observations allow determination of kinematics within the cloud (thermal and turbulent motions and outflows), cloud opacities, and kinetic temperatures. We identify two cores within SFO14: a larger primary core nearer the rim (associated with the known UCHII reigion AFGL4029-IRS1) and a weaker core approximately 2' east of the primary. These cores are apparent in both NH3 and CO maps, although positions of peak molecular emission vary by about 20". The primary core shows morphological evidence of interaction with the rim in both NH3 and CO species. These CO and NH3 observations combine with earlier observations (including 8 µm and radio emission maps) to make SFO14 one of the more convincing examples of RDI-triggered star formation. Extending these studies to a larger sample of bright-rimmed clouds is expected to verify the role of RDI as a significant contributor to the galactic IMF.

Figura, Charles C.; Morgan, L.; Moore, T.; Urquhart, J.

2011-01-01

398

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

399

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

400

Kinematics of transition during human accelerated sprinting  

PubMed Central

ABSTRACT This study investigated kinematics of human accelerated sprinting through 50?m and examined whether there is transition and changes in acceleration strategies during the entire acceleration phase. Twelve male sprinters performed a 60-m sprint, during which step-to-step kinematics were captured using 60 infrared cameras. To detect the transition during the acceleration phase, the mean height of the whole-body centre of gravity (CG) during the support phase was adopted as a measure. Detection methods found two transitions during the entire acceleration phase of maximal sprinting, and the acceleration phase could thus be divided into initial, middle, and final sections. Discriminable kinematic changes were found when the sprinters crossed the detected first transition—the foot contacting the ground in front of the CG, the knee-joint starting to flex during the support phase, terminating an increase in step frequency—and second transition—the termination of changes in body postures and the start of a slight decrease in the intensity of hip-joint movements, thus validating the employed methods. In each acceleration section, different contributions of lower-extremity segments to increase in the CG forward velocity—thigh and shank for the initial section, thigh, shank, and foot for the middle section, shank and foot for the final section—were verified, establishing different acceleration strategies during the entire acceleration phase. In conclusion, there are presumably two transitions during human maximal accelerated sprinting that divide the entire acceleration phase into three sections, and different acceleration strategies represented by the contributions of the segments for running speed are employed. PMID:24996923

Nagahara, Ryu; Matsubayashi, Takeo; Matsuo, Akifumi; Zushi, Koji

2014-01-01

401

Geophysical diffraction tomography and waveform inversion: Applications to high resolution seismic data  

NASA Astrophysics Data System (ADS)

We apply two different techniques to analyze high resolution seismic data from surface and borehole measurements made at a groundwater contamination site at Hill Air Force Base, Ogden, Utah. Two vertical seismic profiles and surface data were recorded simultaneously in and between two 15m deep boreholes separated by 21m. The seismic source was a 223 rifle fired on the surface between the two boreholes, generating signals with energy up to ~300Hz. The size of the target area is roughly the order of a few mean wavelengths in the dataset. The relatively large ratio of mean wavelength ( ~5m) to the scale of structural detail in this high-resolution experiment (<1m) necessitates the application of diffraction tomography and waveform inversion methods. In the first method, we use a form of geophysical diffraction tomography based on the modified Kaczmarz method so that uncertainty in the data can be taken into account and other constraints can be incorporated. The forward model is a linearized Born or Rytov approximation formulated in the frequency domain. The inverse model is obtained using the modified Kaczmarz method where the relaxation parameter is a function of weights estimated from the signal/noise ratio in the data set. Using different weights the image is generated iteratively by back projecting misfits in the data space into velocity corrections in the model space. In theory, multiple-frequencies and non-uniform data sampling can be handled easily. In the second technique, full waveform inversion, the inverse problem is posed as nonlinear data fitting where the unknown parameters are solved by minimizing the misfit between the predicted data and the observed data. A gradient-type approach is applied to solve these problems in which the Jacobian and its adjoint are calculated for given model and data vectors. We present an explicit finite difference time stepping scheme to compute the forward model and its adjoint. Waveform data fitting driven by finite difference simulations can be based on different physical modeling assumptions, from acoustic to viscoelastic propagation. Our finite difference class defines an operator in the sense of the Hilbert Class Library (HCL), a C++ software package for optimization (Cockenback, and Symes, 1996). A wide range of gradient type inversion algorithms using HCL as a platform can be tested.

Gao, F.; Shen, P.; Symes, W. W.; Zelt, C. A.; Levander, A.

2001-12-01

402

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

403

The kinematic properties of isolated elliptical galaxies  

NASA Astrophysics Data System (ADS)

Ellipticals in very low density environments are extremely rare but hold important clues about galaxy formation and evolution. We present results of an investigation of their internal dynamics. We observe a dichotomy in kinematic properties similar to that in normal ellipticals. We compare the positions of isolated ellipticals with respect to the Fundamental Plane of normal ellipticals and find that they fall onto it, with the exception of NGC 2865. This shows that isolated ellipticals are structurally similar to normal ellipticals, and do not have very young ages, although some have signs of past mergers or interactions.

Hau, George K. T.; Forbes, Duncan A.; Reda, Fatma

2004-07-01

404

Kinematic coupling in continuum atomic scattering  

NASA Astrophysics Data System (ADS)

I present here a new three-body wavefunction which is a product of five Kinematically Coupled Coulomb waves. The KC5C wavefunction is valid through second order in all scattering regions and satisfies all asymptotic boundary conditions of the Schrödinger equation. The Brauner, Briggs and Klar (BBK) and Alt and Mukhanedzhanov (AM) continuum state wavefunction models are developed here within a unified notation. The new, Kinematic Coupling model incorporates aspects of both of these previous models and combines the reduced charge potential, discussed in the AM model, with the kinetic energy and allows me to retain the exact three-body Hamiltonian by introducing an exact interaction potential. With this, I assert a triple product form for the wavefunction, which incorporates the known continuum Coulomb eigenstates of the asymptotic Hamiltonian in the region ?? and a third unknown function. This ansatz is then substituted into the exact Schrödinger equation and I find solutions that match smoothly with the Redmond-Merkuriev 3C wavefunction in region ?O, where all of the particles are far apart. I also find that a symmetric and complete description of the local momenta arises naturally. Unlike the local momenta of the AM model however, these depend on the conjugate coordinates and yield both distortion and coupling effects. The strength of the Kinematic Coupling model is then illustrated by showing that it contains the appropriate two-body coalescence, and reproduces and improves upon the results of the BBK and AM models in the region ??, where two of the particles remain close. Moreover, because the distortion terms are vanishingly small at large radial separations and all energies, and identically zero along curves that are determined by the TDCS scattering angles, the KC5C wavefunction may be extended into the interior region. While the Kinematic Coupling framework indicates why the paradigm 3C wavefunction is so successful at describing both electron-ion scattering and some photo-ionization processes, I find that local effects may be important in heavy ion-atom scattering events. This point is illustrated by consideration of the H**2 continuum state, which is relevant in the breakup (H+3) *-->H++H**2-->H ++H++H- , studied by Wiese. I show that the local distortion effects provide an explanation for the observed asymmetry in the experimental data and thus illustrate the importance and validity of the local momenta herein formulated. I suggest that the KC5C wavefunction replace the paradigm 3C wavefunction and that the local distortion be treated as a vector potential, thus making the local momenta a necessary gauge constraint in a complete description of the three-body Coulomb interaction.

Schillaci, Michael Jay

1999-12-01

405

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

406

Galaxy kinematics from counter-dispersed imaging  

E-print Network

Determining the internal kinematics of a galaxy from planetary nebulae (PN) is usually a two step process in which the candidate PN are first identified in a target galaxy and then, in a follow up run, spectra are obtained. We have implemented a new technique in which two dispersed images at the wavelength of the [OIII] emission line at 5007A are combined to yield positions, magnitudes and velocities of the PN population in a single step. A reduction in observing time of about a factor 2 is attainable. We present here the proof-of-principle results.

N. G. Douglas; K. Taylor

1998-09-04

407

Kinematic Dynamo In Turbulent Circumstellar Disks  

NASA Technical Reports Server (NTRS)

Many circumstellar disks associated with objects ranging from protoplanetary nebulae, to accretion disks around compact stars allow for the generation of magnetic fields by an (alpha)omega dynamo. We have applied kinematic dynamo formalism to geometrically thin accretion disks. We calculate, in the framework of an adiabatic approximation, the normal mode solutions for dynamos operating in disks around compact stars. We then describe the criteria for a viable dynamo in protoplanetary nebulae, and discuss the particular features that make accretion disk dynamos different from planetary, stellar, and galactic dynamos.

Stepinski, T.

1993-01-01

408

Sagittal Knee Kinematics following Hamstring Lengthening  

PubMed Central

The purpose of this study was to analyze sagittal knee kinematics following hamstring lengthening. A retrospective analysis was performed of 16 children (32 knees) with cerebral palsy who underwent hamstring lengthening as an isolated surgical procedure. Gait analysis was performed prior to surgery and at a minimum of one year after surgery. Decreased stance maximum knee flexion, stance minimum knee flexion, swing maximum knee flexion, and swing minimum knee flexion were noted. Total knee excursion increased. The present study confirmed the previously reported increase in total knee excursion with decrease in stance minimum and swing maximum knee flexion after hamstring lengthening. PMID:16789447

Carney, Brian T; Oeffinger, Donna; Meo, Anne Marie

2006-01-01

409

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

410

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

411

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

412

Canopy Components Temperature Retrieval through Bayesian inversion of Directional measurements  

NASA Astrophysics Data System (ADS)

In the calculation of Evapotranspiration the kinematic temperature of the individual canopy components plays a crucial role. Most remote sensing algorithms, like SEBAL and SEBS, use a single surface temperature to calculate the evapotranspiration. These algorithms break down when used for canopies with a heterogeneous kinematic temperature profile. A two-source or four-source approach would result in much more realistic values of the evapotranspiration. Single view Nadir looking sensors are not able to extract the multiple kinetic temperatures with high precision. The use of multi-directional sensors is therefore essential. A bi-angular setup is sufficient to separate soil and canopy temperatures (e.g. Jia et al. 2003). For separation of sunlit and shaded soil or vegetation temperatures measurements at additional angles are needed. Calculation of the component temperatures from measured thermal radiances requires the use of more sophisticated radiative transfer models, because the use of fractional vegetation cover alone is no longer sufficient for an inversion scheme for four components. The radiative transfer model used for the calculation of the component temperatures was the four stream SAIL radiative transfer model (Verhoef et al. 2007). We present the algorithm used and the results obtained for the Bayesian inversion. The results were obtained using several directional measurement configurations. The configurations were chosen such to represent various present and future satellite-borne sensors. In this way the configurations give a clear indication of the possibilities of multi-directional thermal remote sensing. References Jia. L. Li, Z. -I., Menenti, M., Su, Z., Verhoef, W. and Wan, Z. (2003), "A practical algorithm to infer soil and foliage component temperatures from bi-angular ATSR-2 data", International Journal of Remote Sensing, 24:23, 4739-4760. Verhoef, W. Jia, L. Xiao, Q. Su, Z., (2007), "Unified optical-thermal four-stream radiative transfer theory for homogeneous vegetation canopies", IEEE Transactions on Geoscience and Remote Sensing, 45(6:2) 1808-1822.

Timmermans, J.; Verhoef, W.; van der Tol, C.; Jia, L.; Su, Z.

2008-12-01

413

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

414

Multiplanar breast kinematics during different exercise modalities.  

PubMed

Abstract Multiplanar breast movement reduction is crucial to increasing physical activity participation amongst women. To date, research has focused on breast movement during running, but until breast movement is understood during different exercise modalities, the breast support requirements for specific activities are unknown. To understand breast support requirements during different exercise modalities, this study aimed to determine multiplanar breast kinematics during running, jumping and agility tasks. Sixteen 32D participants had markers attached to their right nipple and torso. Relative multiplanar breast displacement was calculated during bare-breasted treadmill running (10 kph), maximum countermovement jumping and an agility t-test. Exercise modality influenced the magnitude and direction of breast displacement, velocity and acceleration (p < .05). Jumping produced greater vertical breast displacement (.09 m) but less mediolateral breast displacement (.05 m) than running or the agility task, but agility tasks produced the highest multiplanar breast velocities and acceleration. Breast movement during jumping was predominantly in the vertical direction, whereas the agility task produced a greater percentage of mediolateral breast acceleration than running or jumping. Exercise modality impacted upon the magnitude and distribution of bare-breasted multiplanar breast kinematics in this homogenous 32D cohort. Therefore, to reduce breast movement in women of a 32D bra size, manufacturers may wish to design sport-specific products, with greater vertical support for exercise modalities incorporating jumping and greater mediolateral support for agility tasks. PMID:24942053

Risius, Deborah; Milligan, Alexandra; Mills, Chris; Scurr, Joanna

2015-03-01

415

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

416

The kinematic signature of voluntary actions.  

PubMed

Research in the field of psychology and cognitive neuroscience has begun to explore the functional underpinnings of voluntary actions and how they differ from stimulus-driven actions. From these studies one can conclude that the two action modes differ with respect to their neural and behavioural correlates. So far, however, no study has investigated whether the voluntary and stimulus-driven actions also differ in terms of motor programming. We report two experiments in which participants had to perform either voluntary or stimulus-driven reach-to-grasp actions upon the same stimulus. Using kinematic methods, in Experiment 1 we obtained evidence that voluntary actions and stimulus-driven actions translate into differential movement patterns. Results for Experiments 2 suggest that selecting what to do, when to act, and whether to act are characterized by specific kinematic signatures and affect different aspects of the reach-to-grasp movement in a selective fashion. These findings add to current models of volition suggesting that voluntary action control results from an interplay of dissociable subfunctions related to specific decision components: what action execute, when to execute an action, and whether to execute any action. PMID:25264611

Becchio, Cristina; Zanatto, Debora; Straulino, Elisa; Cavallo, Andrea; Sartori, Giuseppe; Castiello, Umberto

2014-10-01

417

Kinematics of healthy and meniscal repaired knees.  

PubMed

Differences have been reported between in vitro and in vivo meniscal kinematics, and no clinical study to date has investigated the effect of meniscal repair on meniscal kinematics. Eleven subjects with healthy knees and eight subjects who had undergone meniscal repair for an isolated tear were scanned using magnetic resonance imaging. Sagittal plane scanning was performed at 0, 30, 60, 90, and 120 degrees of knee flexion. The mean composite lateral meniscus movements for the normal and meniscal-repaired subjects were 6.85 mm and 6.01 mm, respectively. The mean composite medial meniscus movement for the normal and meniscal repaired subjects were 8.22 mm and 5.91 mm, respectively. Anterior horn movements of the lateral and medial meniscus of normal subjects were 7.5 and 8.9 mm, respectively. The posterior horns of the lateral meniscus and medial meniscus displaced 6.2 mm and 7.6 mm, respectively. In comparing meniscal-repair subjects to the subjects with healthy knees, the lateral meniscus displaced approximately 6 mm for both groups. However, the medial meniscus moved 8.2 mm for the normal subjects and only 5.91 mm for the meniscal repair subjects. Posterior horn movement of the medial meniscus was determined to be reduced following meniscal repair. PMID:16392442

Epler, Marcia; Sitler, Michael; Moyer, Raymond

2005-01-01

418

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

419

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

420

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

421

Inversions of Stokes profiles revisited  

NASA Astrophysics Data System (ADS)

The last thirty years have witnessed the appearance of a number of techniques that have revolutionized our way to measure magnetic fields, namely, the so-called inversions of the radiative transfer equation techniques. Starting from simple models and solutions of the transfer equation and ending with sophisticated processes including full numeric solution of the equation and instrumental effects at the same time, passing through different model approaches and mathematical tools, inversion techniques have become common usage for solar observers. A revision of the ideas, hypotheses, advantages, limitations, and constraints behind inversions is presented, beginning with critical reviews of commonly accepted approximations that are becoming useless as long as new instrumentation is providing better and better observables. The advent of state-of-the-art computing tools increase our capabilities for finer analyses of these new observations.

Del Toro Iniesta, Jose Carlos

422

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

423

Inverse methods for radiation transport  

NASA Astrophysics Data System (ADS)

Implicit optimization methods for solving the inverse transport problems of interface location identification, source isotope weight fraction identification, shield material identification, and material mass density identification are explored. Among these optimization methods are the Schwinger inverse method, Levenberg-Marquardt method, and evolutionary algorithms. Inverse problems are studied in one-dimensional spherical and two-dimensional cylindrical geometries. The scalar fluxes of unscattered gamma-ray lines, leakages of neutron-induced gamma-ray lines, and/or neutron multiplication in the system are assumed to be measured. Each optimization method is studied on numerical test problems in which the measured data is simulated using the same deterministic transport code used in the optimization process (assuming perfectly consistent measurements) and using a Monte Carlo code (assuming less-consistent, more realistic measurements). The Schwinger inverse method and Levenberg-Marquardt methods are found to be successful for problems with relatively few (i.e. 4 or fewer) unknown parameters, with the former being the best for unknown isotope problems and the latter being more adept at interface location, unknown material mass density, and mixed parameter problems. A study of a variety of evolutionary algorithms indicates that the differential evolution method is the best for inverse transport problems, and outperforms the Levenberg-Marquardt method on problems with large numbers of unknowns. An algorithm created by combining different variants of the differential evolution method is shown to be highly successful on spherical problems with unscattered gamma-ray lines, while a basic differential evolution approach is more useful for problems with scattering and in cylindrical geometries. A hybrid differential evolution/Levenberg-Marquardt algorithm also was found to show promise for fast and robust solution of inverse problems.

Bledsoe, Keith C.

424

Kinematics, fragmentation, and heating of molecular streamers in the Orion ridge.  

NASA Astrophysics Data System (ADS)

The extended molecular ridge of OMC-1 surrounding the Orion-KL high mass star forming core has been found to contain a striking pattern of long clumpy filaments which fan out to 0.5 pc from their base in Orion-KL (Martin-Pintado et al., 1990; Murata et al., 1990; Wiseman and Ho, 1994). To clarify the structure and kinematics of the region over a large scale at high angular resolution (8? and high velocity resolution (0.3 km s-1), the authors have constructed a linear mosaic of 10 adjacent VLA fields observed in the NH3 (1,1) and (2,2) rotation-inversion lines covering a 3' by 8' region encompassing the KL core.

Wiseman, J. J.; Ho, P. T. P.

425

K to pi pi Amplitudes at Unphysical Kinematics Using Domain Wall Fermions  

E-print Network

The use of chiral perturbation theory in extracting physical K to pi pi matrix elements from matrix elements calculated at unphysical kinematics is outlined. In particular, the possibility of utilizing pions with non-zero momentum in the final state, and of using partial quenching is discussed. Preliminary (not physically normalized) Delta I=3/2 (27,1) K to pi pi matrix elements are calculated on the RBC/UKQCD $24^3 \\times 64$, $L_s=16$ lattices, using 2+1 dynamical flavors and domain wall fermions, with an inverse lattice spacing of $a^{-1}=1.729(28) GeV$. Effective mass plots are presented for a light sea quark mass of $m_l^{sea}=0.005$, and various valence quark masses. The plateaux are fit and $E_{\\pi\\pi}-m_K$ is extracted.

Matthew Lightman

2007-11-26

426

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

427

A study of generalized inverses  

E-print Network

of the linear equation Ax = b where A is an mxn matrix. It is in this study of solutions, or "best" solutions, to linear equations that we find the most useful application of the general- ized inverse. In order to prove the principal result of this chapter...-square solution to the I 0 linear equation Ax = b is based on Autonne's theorem that any matrix A is unitarily equivalent to a diagonal matrix. Two techniques for computing the generalized inverse of a matrix are discussed and examples are given to illustrate...

McKinney, Nancy Lee

2012-06-07

428

Kinematics of the South Atlantic rift  

NASA Astrophysics Data System (ADS)

The South Atlantic rift basin evolved as branch of a large Jurassic-Cretaceous intraplate rift zone between the African and South American plates during the final breakup of western Gondwana. While the relative motions between South America and Africa for post-breakup times are well resolved, many issues pertaining to the fit reconstruction and particular the relation between kinematics and lithosphere dynamics during pre-breakup remain unclear in currently published plate models. We have compiled and assimilated data from these intraplated rifts and constructed a revised plate kinematic model for the pre-breakup evolution of the South Atlantic. Based on structural restoration of the conjugate South Atlantic margins and intracontinental rift basins in Africa and South America, we achieve a tight fit reconstruction which eliminates the need for previously inferred large intracontinental shear zones, in particular in Patagonian South America. By quantitatively accounting for crustal deformation in the Central and West African rift zone, we have been able to indirectly construct the kinematic history of the pre-breakup evolution of the conjugate West African-Brazilian margins. Our model suggests a causal link between changes in extension direction and velocity during continental extension and the generation of marginal structures such as the enigmatic Pre-salt sag basin and the São Paulo High. We model an initial E-W directed extension between South America and Africa (fixed in present-day position) at very low extensional velocities until Upper Hauterivian times (?126 Ma) when rift activity along in the equatorial Atlantic domain started to increase significantly. During this initial ?17 Myr-long stretching episode the Pre-salt basin width on the conjugate Brazilian and West African margins is generated. An intermediate stage between 126.57 Ma and Base Aptian is characterised by strain localisation, rapid lithospheric weakening in the equatorial Atlantic domain, resulting in both progressively increasing extensional velocities as well as a significant rotation of the extension direction to NE-SW. From Base Aptian onwards diachronous lithospheric breakup occurred along the central South Atlantic rift, first in the Sergipe-Alagoas/Rio Muni margin segment in the northernmost South Atlantic. Final breakup between South America and Africa occurred in the conjugate Santos-Benguela margin segment at around 113 Ma and in the Equatorial Atlantic domain between the Ghanaian Ridge and the Piauí-Ceará margin at 103 Ma. We conclude that such a multi-velocity, multi-directional rift history exerts primary control on the evolution of this conjugate passive margins systems and can explain the first order tectonic structures along the South Atlantic and possibly other passive margins.

Heine, C.; Zoethout, J.; Müller, R. D.

2013-01-01

429

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

430

Kinematic Error Correction for Minimally Invasive Surgical Robots  

E-print Network

. To reach the surgical site near the chest wall, the instrument shaft applies significant torque to the portKinematic Error Correction for Minimally Invasive Surgical Robots Ryan A. Beasley and Robert D. Keywords-surgical robot, image guidance, kinematic error I. INTRODUCTION Minimally invasive surgery (MIS

431

Constrained multi-objective trajectory planning of parallel kinematic machines  

Microsoft Academic Search

This paper presents a new approach to multi-objective dynamic trajectory planning of parallel kinematic machines (PKM) under task, workspace and manipulator constraints. The robot kinematic and dynamic model, (including actuators) is first developed. Then the proposed trajectory planning system is introduced. It minimizes electrical and kinetic energy, robot traveling time separating two sampling periods, and maximizes a measure of manipulability

Amar Khoukhi; Luc Baron; Marek Balazinski

2009-01-01

432

Kinematic Decoupling in Mechanisms and Application to a Passive Hand  

E-print Network

Kinematic Decoupling in Mechanisms and Application to a Passive Hand Controller Design Vincent, 1992 Observations regarding the kinematics of mechanisms are applied to the synthesis of a passive hand yet effective hand-held mechanism in- tended to be used as an input device. Such a device can be used

Hayward, Vincent

433

KINEMATIC ANALYSIS OF A NEW PARALLEL MACHINE TOOL: THE ORTHOGLIDE  

E-print Network

KINEMATIC ANALYSIS OF A NEW PARALLEL MACHINE TOOL: THE ORTHOGLIDE P. WENGER and D. CHABLAT Institut singularities or self-collisions. Parallel kinematic machine tools attract the interest of more and more). Despite this, it is worth noting that many users of machine tools are still not convinced by the potential

Paris-Sud XI, Université de

434

THE DESIGN OF PARALLEL KINEMATIC MACHINE TOOLS USING KINETOSTATIC PERFORMANCE  

E-print Network

1 THE DESIGN OF PARALLEL KINEMATIC MACHINE TOOLS USING KINETOSTATIC PERFORMANCE CRITERIA Félix Majou, Philippe Wenger, Damien Chablat* 1. INTRODUCTION Most industrial machine tools have a serial dynamic performances. However, the design of a parallel kinematic machine tool (PKMT) is a hard task

Paris-Sud XI, Université de

435

Kinematic optimization for isotropic stiffness of redundantly actuated parallel manipulators  

Microsoft Academic Search

? Abstract— A kinematic optimization procedure for redundantly actuated parallel manipulator is developed to ensure the isotropic antagonistic stiffness in a workspace. The kinematic parameters of the mechanism are optimized to maximize and equal out antagonistic stiffness of the redundantly actuated manipulator when size and shape of the usable workspace are given but position in the entire workspace is not.

Hyunpyo Shin; SungCheul Lee; Jay I. Jeong; Jongwon Kim

2011-01-01

436

Kinematic Design of Modular Reconfigurable InParallel Robots  

Microsoft Academic Search

This paper describes the kinematic design issues of a modular reconfigurable parallel robot. Two types of robot modules, the fixed-dimension joint modules and the variable dimension link modules that can be custom-designed rapidly, are used to facilitate the complex design effort. Module selection and robot configuration enumeration are discussed. The kinematic analysis of modular parallel robots is based on a

Guilin Yang; I-ming Chen; Wee Kiat Lim; Song Huat Yeo

2001-01-01

437

Efficient kinematic transformations for the PUMA 560 robot  

Microsoft Academic Search

Efficient solutions for the kinematic positions, velocities, and accelerations for the six-degree-of-freedom PUMA 560 robot are presented. The kinematic problem is defined as the transformation from the Cartesian space to the joint space and vice versa. The solution method is based on a method that fully exploits the special geometry of the robot in the derivation of the solution. Special

S. Elgazzar; Cartesian Vector

1985-01-01

438

Definition sets for the Direct Kinematics of Parallel Manipulators  

E-print Network

Definition sets for the Direct Kinematics of Parallel Manipulators Philippe WENGER, Damien CHABLAT several solutions to the direct kinematic problem without meeting a singularity, thus meaning newly defined sets. This study is illustrated all along the paper with a 3-RPR planar parallel

Boyer, Edmond

439

Advances in Polynomial Continuation for Solving Problems in Kinematics  

E-print Network

Advances in Polynomial Continuation for Solving Problems in Kinematics Andrew J. Sommese # Jan and planar joints are all allowed. Moreover, many higher­order contact joints are also described seems to have been first applied to kinematics in [13, 14], as a heuristic, and later by [21

Sommese, Andrew J.

440

Direct Kinematic Mapping for General Planar Parallel Manipulators  

Microsoft Academic Search

Planar kinematic mapping yields a highly compact general symbolic uni- variate polynomial solution to direct kine- matics problems for all three legged, three degree of freedom planar parallel manipula- tors. Direct kinematics solutions of planar parallel robots with arbitrary mixed leg ar- chitecture are exposed for the first time. Cir- cle and line constraints in both the moving frame as

P. J. Zsombor-Murray

2002-01-01

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