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1

JFKengine: A Jacobian and Forward Kinematics Generator

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

Numerical pole assignment by eigenvalue Jacobian inversion

NASA Technical Reports Server (NTRS)

A numerical procedure for solving the linear pole placement problem is developed which operates by the inversion of an analytically determined eigenvalue Jacobian matrix. Attention is given to convergence characteristics and pathological situations. It is not concluded that the algorithm developed is suitable for computer-aided control system design with particular reference to the scan platform pointing control system for the Galileo spacecraft.

Sevaston, George E.

1986-01-01

3

Inverse kinematic algorithms for redundant systems

An iterative method of computing the solution of the inverse kinematic problem is developed for redundant systems using the transpose of the Jacobian matrix instead of the pseudoinverse. The solutions may be optimized on a criterion function or on physical constraints, such as obstacle avoidance. Stability and convergence of the method are shown. Although its convergence rate is only about

H. Das; J.-E. Slotine; T. B. Sheridan

1988-01-01

4

Improved numerical inverse kinematics for human pose estimation

NASA Astrophysics Data System (ADS)

We propose a real-time pose estimation method that addresses the weaknesses of the numerical inverse kinematics method. Using conventional inverse kinematics based on the numerical method requires many iterations; moreover, a singularity in the Jacobian matrix as well as a local minimum problem can occur. To solve these problems, we propose an inverse kinematics method combined with an unscented Kalman filter (UKF) to recover intermediate joint information. Because the numerical inverse kinematics method optimizes a state, the solution can often converge to the local minimum and require many iterations. We use several sigma points for analysis to find the optimum state by using an unscented transform. The improved method using a UKF converges faster than the numerical inverse kinematics method for the global minimum of the existing inverse kinematics. We use 2-D image processes to extract body areas from the input images, and a 3-D reconstruction algorithm is used to estimate the 3-D positions of the extracted human body area. Using the improved method, we generate intermediate joints for each body part and the results show that the proposed method reduces the computational complexity and increases the accuracy of estimation compared to conventional numerical inverse kinematics.

Seo, Yung-Ho; Lee, Chil-Woo; Choi, Jong-Soo

2011-03-01

5

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

6

Geometry and kinematic evolution of inversion structures

Positive inversion structures form by the compressional reactivation of preexisting extensional structures. Experimental models and observations of natural structures are used to develop quantitative models for the geometry and kinematic evolution of inversion structures. In this paper, I analyze two main formation mechanisms of inversion structures: (1) fault-propagation folding on planar faults, and (2) fault-bend folding on listric faults. Inversion

1993-01-01

7

Transmission-Constrained Inverse Residual Demand Jacobian Matrix in Electricity Markets

A generation firm in an electricity market may own multiple generators located at multiple locations. This paper gen- eralizes the concept of transmission-constrained residual demand from a single generator's perspective to that of a generation firm. We calculate the derivative of a generation firm's inverse residual demand function, i.e., the Jacobian matrix, based on a multi-pa- rameter sensitivity analysis of

Lin Xu; Ross Baldick; Yohan Sutjandra

2011-01-01

8

Wrist-Partitioned, Inverse Kinematic Accelerations and Manipulator Dynamics

An efficient algorithm is presented for the calculation of the inverse kinematic accelerations for a six-degree-of-freedom manipulator with a spherical wrist. The inverse kinematic calculation is shown to work synergistically with the inverse dynamic calculation, producing kinematic parameters needed in the recursive Newton-Euler dynamics formulation. Additional savings in the dynamic computation are noted for a class of kinematically well-structured manipulators,

John M. Hollerbach; Gideon Sahar

1983-01-01

9

Inverse Kinematics Solution of 3DOF Planar Robot using ANFIS

One of the most important problems in robot kinematics and control is, find- ing the solution of Inverse Kinematics. Traditional methods such as geometric, iterative and algebraic are inadequate if the joint structure of the manipulator is more complex. As the complexity of robot increases, obtaining the inverse kinematics is difficult and computation- ally expensive. In this paper, using the

Srinivasan Alavandar; M. J. Nigam

2008-01-01

10

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

11

RBF networks-based inverse kinematics of 6R manipulator

From the point of view of set theory and mathematics, the relation between the forward kinematics (FK) and the inverse kinematics (IK) can be regarded as a nonlinear mapping between the joint space and the operation space of the robot manipulator. Considering the powerful ability of the artificial neural networks (ANN) to process nonlinear mapping relations, the IK problem can

Pei-Yan Zhang; Tian-Sheng Lü; Li-Bo Song

2005-01-01

12

Inverse Kinematic Analysis of Human Hand Thumb Model

NASA Astrophysics Data System (ADS)

This paper deals with a kinematic model of the thumb of the human hand. The proposed model has 3 degrees of freedom being able to model the movements of the thumb tip with respect to the wrist joint centre. The kinematic equations are derived based on Denavit-Hartenberg Convention and solved in both direct and inverse way. Inverse kinematic analysis of human hand thumb model reveals multiple and connected solutions which are characteristic to nonlinear systems when the number of equations is greater than number of unknowns and correspond to natural movements of the finger.

Toth-Tascau, Mirela; Pater, Flavius; Stoia, Dan Ioan; Menyhardt, Karoly; Rosu, Serban; Rusu, Lucian; Vigaru, Cosmina

2011-09-01

13

Learning Inverse Kinematics for Pose-Constraint Bimanual Movements

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

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

2010-01-01

14

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

15

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

16

Quasifree electron scattering on atoms in the inverse kinematic system

The measurement of elastic electron scattering is a sensitive tool to test ionic and atomic potentials. Because a dense ionic target is difficult to produce, we use inverse kinematics, i.e. we exchange the roles of projectile and target and transform the cross sections. The absolute singly and doubly differential cross sections for the projectile ionization of He0 (0.1 MeV\\/u) scattered

T. Jalowy; M. Kuzel; R. Wünsch; R. Neugebauer; D. Hofmann; L. Sarkadi; A. Báder; L. Víkor; G. Víkor; P. Focke; D. H. Jakubaßa-Amundsen; M. W. Lucas; G. Sigaud; K. O. Groeneveld

1997-01-01

17

Study on the effect of parameters on source kinematic inversion

NASA Astrophysics Data System (ADS)

Based on observed seismic waveform data, kinematics inversion is the most effective way to research seismic source. Many kinematics inversion methods have been developed. However, the inversion results from different researchers have big difference, even for the same earthquake. To study how various factors impact on the source inversion, we refer 2010 Haiti earthquake to establish a source model and use the numerical experiments to study how these factors affect the inversion results in multi time window inversion method. Our research indicates: (1) The size of each subfault should be more than half wavelength of S wave, meanwhile, in order to guarantee the accuracy of computation, the Green's function of each subfault should get from the superposition of Green's function of uniformly distributed point source, which has a lag, in this subfault. (2) Too much time windows will increase the non-uniqueness of inverse problem and reduce the rank of coefficient matrix. If single time window could do better, we'd better use single time window in seismic source inversion. (3) Moreover, the change of rupture velocity caused by multi time window will be influenced by the epicenter distance of subfault. Only when the distance is moderate, the change is reasonable. Smaller half width of time window will be good for closer subfaults, and farther subfaults need bigger time windows which have bigger half width. (4) In a word, increasing constraints could increases the rank of coefficient matrix and reduce non-uniqueness of inverse problem. The bigger the weight of time smoothing, the bigger the model fitting parameter; when the weight of space smoothing is about 0.5, the model fitting parameter gets the maximal; the model fitting parameter changes with the weight of moment minimization similar to with the weight of time smoothing. Furthermore, the difference of the waveform fitting parameter with different weight is very small, and the trend of the waveform fitting parameter with weight is inconsistent with the trend of the model fitting parameter with weight. Therefore, the size of the waveform fitting parameter is not a good criterion to evaluate the quality of weight. Selected stations should be as much as possible to ensures that the stations distribute in all directions of fault; the higher the degree azimuth coverage, the better the inversion results.

Wen, J.; Chen, X.

2011-12-01

18

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

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

Srinivasan Alavandar; M. J. Nigam

2008-01-01

19

Versatile visual servoing without knowledge of true Jacobian

Proposes a versatile visual servoing control scheme with a Jacobian matrix estimator. The Jacobian matrix estimator does not need a priori knowledge of the kinematic structure and parameters of the robot system, such as camera and link parameters. The proposed visual servoing control scheme ensures the convergence of the image-features to desired trajectories, by using the estimated Jacobian matrix, which

Koh HOSODA; Minoru ASADA

1994-01-01

20

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

21

BP Networks Based Trajectory Planning and Inverse Kinematics of a Reconfigurable Mars Rover

\\u000a The inverse kinematics of series manipulators presents an inherent complexity due to their various structures and kinematics\\u000a constraints. To a novel reconfigurable Mars rover’s arm, the inverse kinematics had been solved by numerical method combined\\u000a with space geometry relations, but the complex calculating process can not be utilized in real-time control. In this paper,\\u000a some actions in common use are

Liping Zhang; Shugen Ma; Bin Li; Guowei Zhang; Binggang Cao

2005-01-01

22

Inelastic Proton Scattering on 21Na in Inverse Kinematics

NASA Astrophysics Data System (ADS)

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

Austin, Roby

2009-10-01

23

An analysis of the inverse kinematics for a 5DOF manipulator

This paper proposes an analytical solution for a 5-DOF manipulator to follow a given trajectory while keeping the orientation\\u000a of one axis in the end-effector frame. The forward kinematics and inverse kinematics for a 5-DOF manipulator are analyzed\\u000a systematically. The singular problem is discussed after the forward kinematics is provided. For any given reachable position\\u000a and orientation of the end-effector,

De Xu; Carlos A. Acosta Calderon; John Q. Gan; Huosheng Hu; Min Tan

2005-01-01

24

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

25

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

26

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

NASA Technical Reports Server (NTRS)

Closed-form direct and inverse kinematics of a new three degree-of-freedom (DOF) parallel manipulator with inextensible limbs and base-mounted actuators are presented. The manipulator has higher resolution and precision than the existing three DOF mechanisms with extensible limbs. Since all of the manipulator actuators are base-mounted; higher payload capacity, smaller actuator sizes, and lower power dissipation can be obtained. The manipulator is suitable for alignment applications where only tip, tilt, and piston motions are significant. The direct kinematics of the manipulator is reduced to solving an eighth-degree polynomial in the square of tangent of half-angle between one of the limbs and the base plane. Hence, there are at most 16 assembly configurations for the manipulator. In addition, it is shown that the 16 solutions are eight pairs of reflected configurations with respect to the base plane. Numerical examples for the direct and inverse kinematics of the manipulator are also presented.

Tahmasebi, Farhad

2004-01-01

27

Database guided computer animation of human grasping using forward and inverse kinematics

This paper addresses the important issue of automating grasping movement in the animation of virtual actors, and presents a methodology and algorithm to generate realistic looking grasping motion of arbitrary shaped objects. A hybrid approach using both forward and inverse kinematics is proposed. A database of predefined body postures and hand trajectories are generalized to adapt to a specific grasp.

Yahya Aydin; Masayuki Nakajima

1999-01-01

28

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

29

Cortical Network Modeling for Inverse Kinematic Computation of an Anthropomorphic Finger

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.

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

2014-01-01

30

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

The {sup 75}As(d,p{gamma}) reaction in inverse kinematics as a surrogate for neutron capture was performed at Oak Ridge National Laboratory using a deuterated plastic target. The intensity of the 165 keV {gamma}-ray from {sup 76}As in coincidence with ejected protons, from exciting {sup 76}As above the neutron separation energy populating a compound state, was measured. A tight geometry of four segmented germanium clover {gamma}-ray detectors together with eight ORRUBA-type silicon-strip charged-particle detectors was used to optimize geometric acceptance. The preliminary analysis of the {sup 75}As experiment, and the efficacy and future plans of the (d,p{gamma}) surrogate campaign in inverse kinematics, are discussed.

Peters, W A; Cizewski, J A; Hatarik, R; O?Malley, P D; Jones, K L; Schmitt, K; Moazen, B H; Chae, K Y; Pittman, S T; Kozub, R L; Vieira, D; Jandel, M; Wilhelmy, J B; Matei, C; Escher, J; Bardayan, D W; Pain, S D; Smith, M S

2009-11-09

31

Investigating the reliability of kinematic source inversion with dynamic rupture models

NASA Astrophysics Data System (ADS)

An essential element of understanding the earthquake source processes is obtaining a reliable source model via geophysical data inversion. However, the epistemic uncertainties in the kinematic source inversion produce a variety of source model estimates for any given event. Thus, as done in the Source Inversion Validation (SIV) project, it is important to validate our inversion methods with synthetic data by testing forward Green's function calculation and comparing various inversion methods. Spontaneous dynamic rupture modeling, which incorporates the conservation laws of continuum mechanics and the constitutive behavior of rocks under frictional sliding, is capable of producing physically self-consistent kinematic description of the fault and its associated seismic wave propagation resulting in ground motions on the surface. Here we develop accurate dynamic rupture simulation of a vertical strike slip fault. Our source model is composed of well-defined asperities (patches of large stress drop) and we assume that fault rupture is governed by the linear slip weakening friction model. The resulting near-source ground motions dominated by low frequency (up to 1Hz) are used for testing our inversion method. We performed various inversion tests and compared estimated solutions with true solutions obtained by the forward dynamic rupture modeling. Our preliminary results show that estimated model spaces could be significantly perturbed, depending on data and modeling schemes used in the inversion, not only in terms of spatial distribution of model parameters, but also in terms of their auto- and cross-correlation structure. The Bayesian approach in source inversion is becoming increasingly popular because of the recent common availability of high performance computing capabilities. We adopted the Bayesian approach in our source inversion test, so that we can more effectively analyze the uncertainty of estimated models and also implement physically guided regularization in the prior. In addition, the recent emergence of high-rate Global Navigation Satellite Systems (GNSS) data can considerably improve the observation capabilities for dynamic surface movements (sampling up to 100 Hz) during large earthquakes. GNSS receivers are used to accurately measure both dynamic and static ground displacements without saturation or sensitivity to tilt and with a sampling interval below 1 second and sub-centimeter accuracy across the frequency spectrum. We expect that we can resolve the issue of relative weighting often faced in multiple data inversion, i.e., joint inversion of both geodetic and seismic data, by inverting ground displacement data recorded by the high rate GNSS receivers.

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

2011-12-01

32

Kinematic and dynamic inversion of the 16 December earthquake in Northern Chile

NASA Astrophysics Data System (ADS)

We study the kinematic and dynamic rupture propagation of the M 6.7, intraplate, intermediate depth, slab push earthquake that occurred 16 December 2007, a month after the large interplate thrust event of Tocopilla, Chile (M 7.7). The occurrence of a slab push event after a large subduction earthquake is well explained by Coulomb stress transfer and crack dynamics. A dense seismic network, equipped with short period and accelerometers was deployed after the event of 14 November 2007 by the Task Force of GFZ Potsdam and the University of Chile in Santiago. This network was in place on December 16 providing the best seismic data set ever recorded for a Chilean earthquake. We have used it to do a detailed study of rupture processes. We localized the main event of December 16 and the aftershocks that occurred within 24 h of the main event. The main event was located at 43 km depth, while the aftershocks distribution covered a circular zone of 5 to 8 km of radius centered on the main shock epicenter and with depth ranging between [39 - 49] km. The aftershocks are distributed on an almost vertical plane that agrees with the almost vertical plane of the fault mechanism (86° dip) and all the aftershock have the same mechanism as the main event. We used eight of the nearest accelerometric records low pass filtered at 1 Hz, two of which were situated right above the hypocenter. We performed a non-linear kinematic inversion based on the neighborhood algorithm (NA) with an L2 norm. The velocity model was derived from previous work by GFZ. The earthquake is very well modeled by a circular rupture of radius between 5 and 8 km that propagated with a very low rupture velocity, that varies between 1 and 2 km/s. We need only a few non-linear parameters to model this event, parameter space has a dimension close to 6. The kinematic solution was validated using a full dynamic inversion method in which the rupture process is modeled using finite differences on a coarse grid with a slip weakening friction law. Dynamic stress drop is large, of the order of 10-50 MPa. Results from dynamic inversion are in good agreement with the kinematic inversion, if we impose a rather large average energy release rate of the order of 30 MJ/m2. We have explored a large area of the parameter space in search for solutions with faster rupture speeds but we have failed to find them. It appears then that this earthquake that occurred very close to the transition zone from steady to stick slip propagated very slowly.

Ruiz, S.; Lancieri, M.; Madariaga, R. I.; Sobiesiak, M.; Campos, J. A.

2009-12-01

33

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

34

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

35

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

36

Recursive inverse kinematics for robot arms via Kalman filtering and Bryson-Frazier smoothing

NASA Technical Reports Server (NTRS)

This paper applies linear filtering and smoothing theory to solve recursively the inverse kinematics problem for serial multilink manipulators. This problem is to find a set of joint angles that achieve a prescribed tip position and/or orientation. A widely applicable numerical search solution is presented. The approach finds the minimum of a generalized distance between the desired and the actual manipulator tip position and/or orientation. Both a first-order steepest-descent gradient search and a second-order Newton-Raphson search are developed. The optimal relaxation factor required for the steepest descent method is computed recursively using an outward/inward procedure similar to those used typically for recursive inverse dynamics calculations. The second-order search requires evaluation of a gradient and an approximate Hessian. A Gauss-Markov approach is used to approximate the Hessian matrix in terms of products of first-order derivatives. This matrix is inverted recursively using a two-stage process of inward Kalman filtering followed by outward smoothing. This two-stage process is analogous to that recently developed by the author to solve by means of spatial filtering and smoothing the forward dynamics problem for serial manipulators.

Rodriguez, G.; Scheid, R. E., Jr.

1987-01-01

37

Essential kinematics for autonomous vehicles

NASA Astrophysics Data System (ADS)

A short tutorial on Homogeneous Transforms is presented covering the triple interpretation of a homogeneous transform as an operator, a coordinate frame, and a coordinate transform. The operator transform duality is derived and its use in the Denavit Hartenberg convention is explained. Forward, inverse, and differential kinematics are derived for a simple manipulator to illustrate concepts. A standard set of coordinate frames is proposed for wheeled mobile robots. It is shown that the RPY transform serves the same purpose as the DH matrix in this case. It serves to interface with vehicle position estimation systems of all kinds, to control and model pan/tilt mechanisms and stabilized platforms, and to model the rigid transforms from place to place on the vehicle. Forward and inverse kinematics and the Euler angle rate to the angular velocity transform are derived for the RPY transform. Projective kinematics for ideal video cameras and laser rangefinders, and the imaging Jacobian relating world space and image space is derived. Finally, the kinematics of the Ackerman steer vehicle is presented for reference purposes. This report is both a tutorial and a reference for the transforms used in the RANGER vehicle controller. It is both because the models keep evolving and it was necessary to provide the tools, mechanisms, and discipline required to continue the evolution.

Kelly, Alonzo

1994-05-01

38

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

39

Coulomb Excitation in Inverse Kinematics of the ^69As beam at the HRIBF

NASA Astrophysics Data System (ADS)

A description of the first radioactive nuclear beam experiment at the Holifield Radioactive Ion Beam Facility, Oak Ridge National Laboratory, will be presented. Coulomb excitation of ^69As beam nuclei was investigated using inverse kinematics in order to overcome the difficulties presented by limited beam intensity and high background rates. The experiment used a 1.0 mg/cm^2 ^12C foil to Coulomb excite 160 MeV ^69As ions (beam intensity about 10^5 ions/s) as they passed through the foil. A high efficiency NaI(Tl) through-well detector was used to observe the deexcitation of these nuclei. The beam nuclei were detected for coincidence purposes upstream of the target with a microchannel plate-aluminized mylar foil assembly and downstream of the target with a plastic scintillator beam stop. A discussion of the challenges presented when measuring Coulomb excitation of radioactive beams will be presented along with results of the experiment. Plans for future work and improvements to the apparatus will be discussed. Work supported by USDOE contract numbers DE-FG02-91ER40609, DE-FG02-88ER40417, DE-AC02-76CH00016, and DE-AC05-96OR22464.

Barton, C. J.; Brenner, D. S.; Casten, R. F.; Zamfir, N. V.; Gill, R. L.; Shapira, D.

1998-04-01

40

Study of 13B(d,p)14B Reaction in Inverse Kinematics with Helios

NASA Astrophysics Data System (ADS)

The ^14B nucleus was studied employing the (d, p) reaction in inverse kinematics using HELIOS at the ATLAS facility at ANL. A beam of ^13B with energy 15.7 MeV/nucleon was produced using the In-Flight method. Protons from the ^13B(d, p)^14B reaction were detected and analyzed using the HELIOS device. Detecting and identifying the recoiling ^13B and ^14B nuclei in a silicon ?E-E telescope at forward angles distinguished bound and unbound states in ^14B. Angular-momentum transfers and relative spectroscopic factors were deduced for the four lowest states in ^14B. The ground and first excited states, 2^- and 1^- respectively, are presumably made up of ?(0p3/2)-?(1s1/2) configurations, while coupling of the proton hole to a d5/2 neutron produces (1,2,3,4)^-. The 0d5/2-1s1/2 splitting in ^14B is expected to be small, producing mixing between the (1,2)^- l = 0 and 2 configurations. The measured spectroscopic factors for neutron transfer will be compared to the predictions of the shell model calculations.

Bedoor, S.; Wuosmaa, A. H.; Lighthall, J. C.; Marley, S. T.; Shetty, D. V.; Alcorta, M.; Back, B. B.; Bertone, P. F.; Rehm, K. E.; Rogers, A. M.; Schiffer, J. P.; Brown, B. A.; Deibel, C. M.

2012-10-01

41

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

Low-lying excited states of 46Ar 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+1 state. This result, combined with existing Coulomb excitation data, yields a ratio of the neutron-to-proton transition matrix elements of Mn\\/Mp=1.19(25)N\\/Z, showing a departure from the proton dominance observed in the N=28

L. A. Riley; M. A. Abdelqader; D. Bazin; M. J. Bojazi; B. A. Brown; C. M. Campbell; J. A. Church; P. D. Cottle; D.-C. Dinca; J. Enders; A. Gade; T. Glasmacher; M. Honma; S. Horibe; Z. Hu; K. W. Kemper; W. F. Mueller; H. Olliver; T. Otsuka; B. C. Perry; B. T. Roeder; B. M. Sherrill; T. P. Spencer; J. R. Terry

2005-01-01

42

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

43

Astrophysical(?,?) reaction in inverse kinematics; Electron screening effect in the beta-decay

NASA Astrophysics Data System (ADS)

The abundance calculations of the p-nuclei produced in explosive stellar sites rely on the Hauser-Feshbach (HF) theory with the alpha-article optical model potential (?-OMP) one of its major ingredients. To date, most of the (?, ?) cross sections measured show that HF calculations can be wrong by a factor of ten or more especially when phenomenological ?-OMP are employed. To investigate the relevant uncertainties entering the HF calculations and furthermore develop global microscopic ?-OMPs, systematic (?, ?) cross-section measurements are necessary. This led us to perform a feasibility study of (?, ?) measurements in inverse kinematics that will allow us to employ also radioactive beams in the future. Hence, the 4He(78Kr,?)82Sr reaction was studied using the LISE3 spectrometer to separate the 82Sr recoils from the primary 78Kr beam. Although an excellent rejection factor > 1010 was achieved, the position of the ions of interest was unexpectedly masked by a secondary beam of high intensity. Given these, new setup improvements are proposed to remove the pollutant ions. Recently, many experiments were conducted in order to study the influence of the environment (especially in a metallic material) on the decay probability of radioactive nuclei. Additionally, hydrogen-like fusion reactions were performed indicating a change in the cross-section due to the influence of the Coulomb field screening induced by quasi-free electrons in metals. This was explained by the Debye screening model which treats metallic electrons within Maxwell-Boltzmann statistics. We measured the decay rate of 19O in metallic, insulating and superconducting environments whereas the electrons in the superconductors should obey the Bose-Einstein statistics. The decay rate measurement was supported by a branching ratios measurement. We found that the effect on the decay rate, if any, is less than the 0.1%, far below the theoretical predictions.

Uji?, P.; de Oliveira, F.; Lagoyannis, A.; Mertzimekis, T. J.; Harissopulos, S.; Demetriou, P.; Spyrou, A.; Stodel, C.; Saint-Laurent, M. G.; Kamalou, O.; Lefebvre-Schuhl, A.; Grevy, S.; Caceres, L.; Lewitowicz, M.; Amthor, M. A.; Perot, L.; Coc, A.; Tatischeff, V.; Kiener, J.; Sorlin, O.; Lepailleur, A.; Assié, M.; Bastin, B.; Achouri, L.; Borcea, R.; Borcea, C.; Stanoiu, M.; de France, G.; Clement, E.; Pautrat, A.; Buta, A.; Gaudefroy, L.; Meot, V.; Deloncle, I.

2012-02-01

44

NASA Astrophysics Data System (ADS)

Published plate reconstructions commonly show significant differences in initial plate configuration and syn-extensional opening directions. The variability of published models is primarily due to the difficulty associated with restoring crustal stretching history. Here we present an inverse non-rigid kinematic method that inverts plate motion and present day crustal thickness to approximate the history of bulk lateral strain and crustal thinning associated with lithospheric stretching. The kinematic link between plate motion and bulk crustal thickness that is used with this method is based on insights obtained from geodynamic models. We implement this approach in open source kinematic modeling software and apply it to test new Early Mesozoic plate kinematic models of the Central Atlantic. This application shows that the patterns of stretching inferred from the syn-rift basins of the Newark Supergroup can be explained if (1) syn-rift Euler pole flow lines were parallel to the Grand Banks transform margin and (2) initial formation of the East Coast Margin Igneous Province was coincident with the formation of the Central Atlantic Magmatic Province. These syn-rift to breakup models of the Central Atlantic lead to better constrained models of early seafloor spreading that show full spreading velocities in the ultraslow regime and within the transition from ultraslow to slow spreading regimes.

Kneller, Erik A.; Johnson, Christopher A.; Karner, Garry D.; Einhorn, Jesse; Queffelec, Thomas A.

2012-12-01

45

Studies of Neutron-Rich Nuclei with (d,p) Reactions in Inverse Kinematics at the HRIBF

Two N=51 isotones have been measured using (d,p) reactions in inverse kinematics at the Holifield Radioactive Beam Facility (HRIBF) of Oak Ridge National Laboratory. Additionally, we have performed a test measurement using a stable 124Sn beam in preparation for measurements of the 2H(130,132Sn,p)131,133Sn reactions. Preliminary results for 83Ge and 85Se suggest a 5/2+ ground state and a 1/2+ first excited state for both isotopes, in agreement with systematics for the N=51 isotones. The excitation energy of the first excited state is shown to drop as the proton number is reduced. Proton angular distributions following the 2H(124Sn,p)125Sn reaction show sensitivity to the l-value of the transfered nucleon and spectroscopic factors are in agreement with previous measurements in normal kinematics.

Grzywacz-Jones, Kate L [ORNL; Baktash, Cyrus [ORNL; Bardayan, Daniel W [ORNL; Blackmon, Jeff C [ORNL; Catford, Wilton N [ORNL; Cizewski, Jolie [ORNL; Fitzgerald, Ryan [ORNL; Greife, Uwe [ORNL; Gross, Carl J [ORNL; Johnson, Micah [ORNL; KOZUB, RAYMOND L [ORNL; Liang, J Felix [ORNL; Livesay, Jake [ORNL; Ma, Zhanwen [ORNL; Moazen, Brian H [ORNL; Nesaraja, Caroline D [ORNL; Shapira, Dan [ORNL; Smith, Michael Scott [ORNL; Thomas, Jeffrey S [ORNL; Visser, Dale William [ORNL

2005-01-01

46

NASA Astrophysics Data System (ADS)

This research highlights the results obtained from applying the method of inverse kinematics, using Groebner basis theory, to the human gait cycle to extract and identify lower extremity gait signatures. The increased threat from suicide bombers and the force protection issues of today have motivated a team at Air Force Institute of Technology (AFIT) to research pattern recognition in the human gait cycle. The purpose of this research is to identify gait signatures of human subjects and distinguish between subjects carrying a load to those subjects without a load. These signatures were investigated via a model of the lower extremities based on motion capture observations, in particular, foot placement and the joint angles for subjects affected by carrying extra load on the body. The human gait cycle was captured and analyzed using a developed toolkit consisting of an inverse kinematic motion model of the lower extremity and a graphical user interface. Hip, knee, and ankle angles were analyzed to identify gait angle variance and range of motion. Female subjects exhibited the most knee angle variance and produced a proportional correlation between knee flexion and load carriage.

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

2013-05-01

47

The paper deals with the problem of the multiple solutions of the coordinate transformations for an n-link robot manipulator. Aspect decomposition of the admissible domain of the joint space is introduced and an algorithm for automatic computation of Aspect decomposition is presented. This decomposition takes into account the morphology of the robot arm and the kinematic task definition as well.

Paul BORREL; A. Liegeois

1986-01-01

48

Inverse Kinematic Approach Using Groebner Basis Theory Applied to Gait Cycle Analysis.

National Technical Information Service (NTIS)

Kinematics of the human body was researched for the purposes of this study. The force protection issues of today was the motivation to research pattern recognition in the human gait cycle to identify individuals carrying a concealed load on their body. Th...

A. Barki

2013-01-01

49

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

Late Cretaceous inversion structures, which are significant for oil and gas accumulation, are widely distributed throughout the Jiuquan Basin. These structures are primarily made up of inverted faults and fault-related folds. Most of the axial planes of folds are parallel to inverted faults trending north-east, indicating that the principal stress direction was north-west - south-east in the Late Cretaceous. The average inversion ratios of faults in the four sags that were investigated are 0.39, 0.29, 0.38, 0.32. The average inversion ratio in the Jiuquan Basin is 0.34 and the degree of inversion is moderate to strong. As moderate inversion is suitable for forming excellent hydrocarbon traps, there is considered to be significant potential in the basin for the presence of structural traps. ?? 2005 Elsevier Ltd. All rights reserved.

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

2005-01-01

50

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

51

NASA Astrophysics Data System (ADS)

We present a non linear technique to invert strong motion records with the aim of obtaining the final slip and the rupture velocity distributions on the fault plane. Kinematic inversion of strong motion data is an ill-conditioned inverse problem, with several solutions available also in the case of noise-free synthetic data (Blind test on earthquake source inversion,http://www.seismo.ethz.ch/staff/martin/BlindTest.html).On the other hand, complete dynamic inversion still looks impracticable, because of an unclear understanding of the physical mechanisms controlling the energy balance at the rupture tip and a strong correlation between the initial stress field and the parameters of the constitutive law. Hence a strong effort is demanded to increase the robustness of the inversion, looking at the details of the slip and rupture velocity parameterization, at the global exploration techniques, at the efficiency of the cost-function in selecting solutions, at the synthesis process in retrieving the stable features of the rupture. In this study, the forward problem, i.e. the ground motion simulation, is solved evaluating the representation integral in the frequency domain by allowing possible rake variation along the fault plane. The Green's tractions on the fault are computed using the discrete wave-number integration technique that provides the full wave-field in a 1D layered propagation medium. The representation integral is computed through a finite elements technique on a Delaunay triangulation of the fault plane. The rupture velocity is finally defined on a coarser regular grid and rupture times are computed by integration of the eikonal equation. For the inversion, the slip distribution is parameterized by 2D overlapping Gaussian functions, which can easily relate the spectrum of the possible solutions with the minimum resolvable wavelength, related to source-station distribution and data processing. The inverse problem is solved by a two-step procedure aimed at separating the computation of the rupture velocity from the evaluation of the slip distribution, the latter being a linear problem, when the rupture velocity is fixed. The non-linear step is solved by optimization of an L2 misfit function between synthetic and real seismograms, and solution is searched by the use of the Neighbourhood Algorithm. The conjugate gradient method is used to solve the linear step instead. The developed methodology has been applied to the M7.2, Iwate Nairiku Miyagi, Japan, earthquake that was recorded by the K-net and Kik-net accelerometric networks.

Lucca, Ernestina; Festa, Gaetano; Emolo, Antonio

2010-05-01

52

Kinematic Point Source Moment Tensor Inversion Using a Hierarchical Bayesian Approach

NASA Astrophysics Data System (ADS)

The seismic moment tensor (MT) reveals details about source processes within the Earth that cause earthquakes. Although uncertainties in MT inversions are important for estimating solution robustness, they are rarely available. When earthquake location is simultaneously recovered with the MT, uncertainties in structural Green's functions also need to be included in the method. The problem becomes nonlinear and uncertainties in the source mechanism cannot be calculated in a simple manner. We have developed a method and software for a hierarchical Bayesian MT inversion to study moderate earthquakes and explosions generating waveform data at regional distances. The Bayesian inversion gives a posterior probability distribution of model parameters, based on prior knowledge about the MT and the model likelihood, determined by the data. MT uncertainties can then be estimated from the posterior probability distribution. The hierarchical Bayes approach enables us to recover the nature of the data noise and the weight of each waveform, treating them as unknowns in the inversion. Critically, data noise covariance matrix is implemented to account for measurement and theory errors. This knowledge, in turn, enables us to recover the solution within a reasonable range of uncertainty; in other words, it prevents us from "fitting the noise" that can lead to erroneous solutions and interpretation. Synthetic experiments were performed to test the codes, particularly the retrieval of non double-couple components of the MT. A suite of synthetic and observed focal mechanisms was used to create the synthetic data. Additionally, we add noise to synthetic data (as a fraction of data rms) to test its effect on the inversion. Experiments are performed using uncorrelated Gaussian white noise, as well as using correlated noise. Parameter space for the event mechanism is sampled exhaustively, while the code rapidly converges towards the input hypocenter location. Both the input mechanism and noise level were retrieved in the inversion. The codes are currently being applied on real data to test earthquakes in a variety of tectonic settings.

Musta?, Marija; Tkal?i?, Hrvoje

2014-05-01

53

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

54

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

55

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

56

Kinematic calibration of a 7 DoF hapic device

Precise positioning and precise force control requirement in haptic devices necessitate the kinematic calibration of the device. Since force control algorithms in haptic interfaces employ Jacobian matrix which includes kinematic model parameters, kinematic calibration is not only important for pose accuracy but also for force control. The deviation of kinematic parameters and joint transmission errors are main reasons disturbing the

Ozgur Baser; E. Ilhan Konukseven

2011-01-01

57

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

NASA Technical Reports Server (NTRS)

This paper presents kinematic equations and solutions for an in-parallel actuated robotic mechanism based on Stewart's platform. These equations are required for inverse position and resolved rate (inverse velocity) platform control. NASA LaRC has a Vehicle Emulator System (VES) platform designed by MIT which is based on Stewart's platform. The inverse position solution is straight-forward and computationally inexpensive. Given the desired position and orientation of the moving platform with respect to the base, the lengths of the prismatic leg actuators are calculated. The forward position solution is more complicated and theoretically has 16 solutions. The position and orientation of the moving platform with respect to the base is calculated given the leg actuator lengths. Two methods are pursued in this paper to solve this problem. The resolved rate (inverse velocity) solution is derived. Given the desired Cartesian velocity of the end-effector, the required leg actuator rates are calculated. The Newton-Raphson Jacobian matrix resulting from the second forward position kinematics solution is a modified inverse Jacobian matrix. Examples and simulations are given for the VES.

Williams, Robert L., II

1992-01-01

58

NASA Astrophysics Data System (ADS)

We present an approach to infer the slip and rupture velocity distributions on the fault plane from the non-linear inversion of the apparent source time functions, obtained from the empirical Green's function deconvolution method. The main advantage of this technique is that it allows overcoming, in the forward modelling, the limitations related to the computation of the Green's function, as the choice of a correct and reliable earth propagation model. We perform a parameter resolution and uncertainty study, which is based on the analysis of the misfit function in the neighbourhood of the best-fitting model. In this paper, we present the results obtained by applying the technique to synthetic and real records from an Mw 4 event which occurred during the 2009 L'Aquila (central Italy) aftershock sequence. Results show a heterogeneous slip distribution, characterized by two main high slip patches located NW of the hypocentre and an average slip of 3.7 cm, corresponding to a seismic model of about 0.82 × 1015 Nm.

Serra, Eugenio Maria Toraldo; Emolo, Antonio; Orefice, Antonella; Zollo, Aldo

2013-08-01

59

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.

2014-01-01

60

National Technical Information Service (NTIS)

Uncertainties in the relative importance of the atmospheric processes maintaining large-scale temperature inversions motivated the study of these processes in the vicinity of a strong low-level subsidence inversion over the eastern United States. The dens...

G. F. Watson

1971-01-01

61

National Technical Information Service (NTIS)

The kinematic model for the Advanced Deburring and Chamfering System (ADACS) robot, which determines the position and orientation of the manipulator end-effector for a given set of joint angles, is developed using the standardized Denavit-Hartenberg metho...

K. A. Stouffer

1992-01-01

62

ERIC Educational Resources Information Center

Inversions are fascinating phenomena. They are reversals of the normal or expected order. They occur across a wide variety of contexts. What do inversions have to do with learning spaces? The author suggests that they are a useful metaphor for the process that is unfolding in higher education with respect to education. On the basis of…

Brown, Malcolm

2009-01-01

63

NSDL National Science Digital Library

In this lesson students are introduced to various types of symmetry. After exploring the symmetries that exist with letters of the alphabet, they make inversions of their own name. Suggestions for implementation and support materials are provided.

2011-01-01

64

Kinematic Modeling of a High Mobility Mars Rover

The paper describes a method for kinematic modeling of the Rocky 7 Mars rover. The model is derived for full six degree of freedom motions enabling movements in x,y,z directions, as well as pitch, roll and yaw rotations. Forward kinematic equations are derived using wheel Jacobian matrices. The individual matrices are then combined to form the composite equation for the

Mahmoud Tarokh; Gregory J. Mcdermott; S. Hayati; J. Hung

1999-01-01

65

NASA Astrophysics Data System (ADS)

We derive the value of H_0 using the inverse diameter and magnitude B-band Tully-Fisher relations and the large all-sky sample KLUN (5171 spiral galaxies). Our kinematical model was that of Peebles centered at Virgo. Our calibrator sample consisted of 15 field galaxies with cepheid distance moduli measured mostly with HST. A straightforward application of the inverse relation yielded H_0~ 80 km s(-1} Mpc({-1})) for the diameter relation and H_0~ 70 km s(-1} Mpc({-1})) for the magnitude relation. H_0 from diameters is about 50 percent and from magnitudes about 30 percent larger than the corresponding direct estimates (cf. Theureau et al. \\cite{Theureau97b}). This discrepancy could not be resolved in terms of a selection effect in log Vmax nor by the dependence of the zero-point on the Hubble type. We showed that a new, calibrator selection bias (Teerikorpi et al. \\cite{Teerikorpi99}), is present. By using samples of signicificant size (N=2142 for diameters and N=1713 for magnitudes) we found for a homogeneous distribution of galaxies (alpha =0): H_0=52(+5}_{-4) km s(-1} Mpc({-1})) for the inverse diameter B-band Tully-Fisher relation, and H_0=53(+6}_{-5) km s(-1} Mpc({-1})) for the inverse magnitude B-band Tully-Fisher relation. Also H_0's from a fractal distribution of galaxies (decreasing radial number density gradient alpha =0.8) agree with the direct predictions. This is the first time when the inverse Tully-Fisher relation clearly lends credence to small values of the Hubble constant H_0 and to long cosmological distance scale consistently supported by Sandage et al. (1995).

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

1999-07-01

66

NASA Astrophysics Data System (ADS)

The present work compliments the application of a methodology, in reviewing and investigating further the kinematic history of faults, based on striation analysis and stress inversion of earthquake focal mechanisms and combines them to refine tectonic modelling and hence improve further hazard assessment. Two areas are chosen for this application: the Bristol Channel, UK and the Ionian Zone, Greece. Striation analysis is carried out in two complementary fault terranes. The first along the northern margin of the Inner Bristol Channel, UK, offers a natural laboratory to study in detail the reactivation history of the inverted Bristol Channel basin; and, the second along the north western coastline of the Ionian Zone, Greece, presents an opportunity to illustrate the relationship between movement of a framework of faults within the external orogenic zone of the Hellenides and the stress deduced from focal mechanisms of earthquakes in the region. The UK example reveals phases of Mesozoic negative inversion of Late Palaeozoic basement frontal and oblique ramp thrust faults, followed by Caenozoic positive inversions of Mesozoic normal and strike slip faults. The Greek example shows an equally composite history of faulting; Tethyan basement strata contain normal faults that pass up sequence and across unconformities into Mesozoic and Caenozoic strata, with thrusts and positively inverted faults recording typical dextral transpression. The fault framework in older strata and the veneers of Recent strata above them display Neotectonic fault histories of sinistral transtension, in addition to the transpression. Since the Ionian Zone lies suitably in the external zone, deformation favours the reactivation of fault lineaments, rather than the genesis of pristine faults. Both examples are used to demonstrate this structural principle. Focal mechanisms of Greek earthquake data are used in stress inversion and the results are applied upon the inherited fault framework and are postulated to reactivate it. For example, structures are selected in the field from the tectonised strata of northern Corfu and from recent geological maps of north western Greece. These data are used in conjunction with the results of stress inversion of focal mechanisms, in order to anticipate and then test the gross senses of fault reactivation. Tests are investigated using structural field techniques and available international striation analysis software modules. The defined framework analysis is applied to both the data from ancient faults, in UK and the focal mechanisms of earthquakes, in Greece. Stress tensors are calculated and fault kinematic histories are evaluated. Hence, this application permits the effects of a modern stress regime to be deduced for a known fault framework, in order to complete and understand fully the kinematic history to the present day. As a corollary, the significant field techniques of tracing major fault lines across regional unconformities and measuring the sense of displacements across these stratigraphic boundaries permit kinematic histories to be defined more precisely in both terranes, than by using only structural techniques.

Melis, Nikolaos S.; Miliorizos, Marios N.; Oshoano Aipoh, Hilary

2013-04-01

67

Few optimization methods exist for path planning of kinematically redundant manipulators. Among these, a universal method is lacking that takes advantage of a manipulator`s redundancy while satisfying possibly varying constraints and task requirements. Full Space Parameterization (FSP) is a new method that generates the entire solution space of underspecified systems of algebraic equations and then calculates the unique solution satisfying specific constraints and optimization criteria. The FSP method has been previously tested on several configurations of the redundant manipulator HERMIES-III. This report deals with the extension of the FSP driver, Inverse Kinematics On Redundant systems (IKOR), to include three-dimensional manipulation systems, possibly incorporating a mobile platform, with and without orientation control. The driver was also extended by integrating two optimized versions of the FSP solution generator as well as the ability to easily port to any manipulator. IKOR was first altered to include the ability to handle orientation control and to integrate an optimized solution generator. The resulting system was tested on a 4 degrees-of-redundancy manipulator arm and was found to successfully perform trajectories with least norm criteria while avoiding obstacles and joint limits. Next, the system was adapted and tested on a manipulator arm placed on a mobile platform yielding 7 degrees of redundancy. After successful testing on least norm trajectories while avoiding obstacles and joint limits, IKORv1.0 was developed. The system was successfully verified using comparisons with a current industry standard, the Moore Penrose Pseudo-Inverse. Finally, IKORv2.0 was created, which includes both the one shot and two step methods, manipulator portability, integration of a second optimized solution generator, and finally a more robust and usable code design.

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

1997-01-01

68

Automatic generation of kinematics for a reconfigurable modular manipulator system

An algorithm is proposed that automatically generates the Denavit-Hartenberg (DH) kinematic parameters of a reconfigurable manipulator. The DH kinematic parameters are then used to obtain the forward kinematic transformation of the system. The authors also address the problem of obtaining the inverse kinematics of reconfigurable manipulators. To automate the inverse kinematics and to make the procedure as general as possible,

Laura Kelmar; Pradeep K. Khosla

1988-01-01

69

NASA Astrophysics Data System (ADS)

We investigated the rupture history of the 2009 April 6th (Mw 6.1) L'Aquila earthquake by using a non-linear inversion of strong motion, GPS and DInSAR data. The joint inversion solution reveals a heterogeneous slip distribution characterized by two main asperities, located up-dip from the hypocentre and south-east wards along strike direction respectively. The imaged rupture velocity is larger in the up-dip than in the along-strike direction. The up-dip and along-strike rupture propagation are separated in time and associated with a Mode II and a Mode III crack, respectively. Our results show that the L'Aquila earthquake featured a very complex rupture, with strong spatial and temporal heterogeneities, suggesting a strong frictional and/or structural control of the rupture process (Cirella et al., 2012). The retrieved source model not only features the best slip distribution, but also provides the complete rupture history (rupture velocity, seismic moment released) that we used in a forward modeling to investigate how source heterogeneities of l'Aquila earthquake affected the spatial variability of the ground motion. We model scenarios on a ';virtual' grid (800 sites) by varying the slip distribution, the nucleation position and by considering either a heterogeneous or a uniform rupture time distribution for each nucleation position. Our results indicate that the relative position between the main patch of slip and the nucleation position on the fault plane strongly influences the ground motion variability also at low-intermediate frequency; moreover, our results suggest that the L'Aquila earthquake may not be intended as the worst-case scenario.

Cirella, A.; Spagnuolo, E.; Piatanesi, A.

2013-12-01

70

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

71

NASA Astrophysics Data System (ADS)

We report on a new experimental setup for the investigation of proton induced reactions on exotic nuclei in inverse kinematics. It was installed and successfully used in the scattering study of intermediate-energy protons ( ˜700 MeV/u) on neutron-rich nuclei 6,8He produced with the FRagment Separator (FRS) at the GSI facility, Darmstadt. A new pure liquid-hydrogen target was successfully adapted allowing to obtain low-background data as compared to commonly used (CH 2) n targets. Absolute differential cross-sections for elastic (p, 6,8He) scattering were obtained at angles corresponding to 0.05?|t|?0.125 (GeV/ c) 2 of the four-momentum transfer squared (- t) leading to the first diffraction minimum and spanning more than two orders of magnitude. They complement an earlier measurement at smaller angles 0.0025?|t|?0.05 (GeV/ c) 2 performed at the same energy with an active target. Both data sets agree well in the overlap region t?0.05 (GeV/ c) 2 and enable a refined and comparative study of the radial distribution of the nuclear matter density.

Kiselev, O. A.; Aksouh, F.; Bleile, A.; Bochkarev, O. V.; Chulkov, L. V.; Cortina-Gil, D.; Dobrovolsky, A. V.; Egelhof, P.; Geissel, H.; Hellström, M.; Isaev, N. B.; Komkov, B. G.; Matoš, M.; Moroz, F. V.; Münzenberg, G.; Mutterer, M.; Mylnikov, V. A.; Neumaier, S. R.; Pribora, V. N.; Seliverstov, D. M.; Sergueev, L. O.; Shrivastava, A.; Sümmerer, K.; Weick, H.; Winkler, M.; Yatsoura, V. I.

2011-06-01

72

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

73

Kinematic programming alternatives for redundant manipulators

In the growing literature on redundant manipulator control, a number of techniques have been proposed for solving the inverse kinemetics problem. Some of these techniques are surveyed with a discussion of strengths and weaknesses of each. A new approach, called the extended Jacobian technique, is also presented. It is argued that because this technique may be expected to lift closed

John Baillieul

1985-01-01

74

Crystal plasticity with Jacobian-Free Newton-Krylov

NASA Astrophysics Data System (ADS)

The objective of this work is to study potential benefits of solving crystal plasticity finite element method (CPFEM) implicit simulations using the Jacobian-Free Newton-Krylov (JFNK) technique. Implicit implementations of CPFEM are usually solved using Newton's method. However, the inherent non-linearity in the flow rule model that characterizes the crystal slip system deformation on occasions would require considerable effort to form the exact analytical Jacobian needed by Newton's method. In this paper we present an alternative using JFNK. As it does not require an exact Jacobian, JFNK can potentially decrease development time. JFNK approximates the effect of the Jacobian through finite differences of the residual vector, allowing modified formulations to be studied with relative ease. We show that the JFNK solution is identical to that obtained using Newton's method and produces quadratic convergence. We also find that preconditioning the JFNK solution with the elastic tensor provides the best computational efficiency.

Chockalingam, K.; Tonks, M. R.; Hales, J. D.; Gaston, D. R.; Millett, P. C.; Zhang, Liangzhe

2013-05-01

75

Direct kinematic solution of a Stewart platform

The Stewart platform is a fully parallel, six-degree-of-freedom manipulator mechanism. Although its inverse kinematics have been extensively studied, no solutions to the direct position kinematics problem have been previously presented in the literature. A solution of the direct kinematics problem of the case in which the six limbs form three concurrent pairs at either the base or the hand member

PRABJOT NANUA; KENNETH J. WALDRON; VASUDEVA MURTHY

1990-01-01

76

Force-free Jacobian equilibria for Vlasov-Maxwell plasmas

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

77

Electrical impedance tomography (EIT) is a fast and cost-effective technique to provide a tomographic conductivity image of a subject from boundary current-voltage data. This paper proposes a time and memory efficient method for solving a large scale 3D EIT inverse problem using a parallel conjugate gradient (CG) algorithm. The 3D EIT system with a large number of measurement data can produce a large size of Jacobian matrix; this could cause difficulties in computer storage and the inversion process. One of challenges in 3D EIT is to decrease the reconstruction time and memory usage, at the same time retaining the image quality. Firstly, a sparse matrix reduction technique is proposed using thresholding to set very small values of the Jacobian matrix to zero. By adjusting the Jacobian matrix into a sparse format, the element with zeros would be eliminated, which results in a saving of memory requirement. Secondly, a block-wise CG method for parallel reconstruction has been developed. The proposed method has been tested using simulated data as well as experimental test samples. Sparse Jacobian with a block-wise CG enables the large scale EIT problem to be solved efficiently. Image quality measures are presented to quantify the effect of sparse matrix reduction in reconstruction results. PMID:23719094

Yang, C L; Wei, H Y; Adler, A; Soleimani, M

2013-06-01

78

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

79

Optimum Kinematic Design for a Seven Degree of Freedom Manipulator

oll axes of the forearm andhand, reducing by one the degrees of freedom.Singularities are manifested in inverse kinematicproblems where it is desired to find joint velocitiesthat correspond to desired hand velocities. Joint velocities` and hand velocities x are related by theJacobian matrix J: x = J `where the 6-dimensional hand velocity x = ( p !)consists of a linear velocity

John M. Hollerbach

1985-01-01

80

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

The relationship is presented between a detailed power system dynamic model and a standard load-flow model. The linearized dynamic model is examined to show how the load-flow Jacobian appears in the system dynamic-state Jacobian for evaluating steady-state stability. Two special cases are given for the situation when singularity of the load-flow Jacobian implies singularity of the system dynamic-state Jacobian. The

P. W. Sauer; M. A. Pai

1990-01-01

81

Model building of biochemical reaction networks typically involves experiments in which changes in the behavior due to natural or experimental perturbations are observed. Computational models of reaction networks are also used in a systems biology approach to study how transitions from a healthy to a diseased state result from changes in genetic or environmental conditions. In this paper we consider the nonlinear inverse problem of inferring information about the Jacobian of a Langevin type network model from covariance data of steady state concentrations associated to two different experimental conditions. Under idealized assumptions on the Langevin fluctuation matrices we prove that relative alterations in the network Jacobian can be uniquely identified when comparing the two data sets. Based on this result and the premise that alteration is locally confined to separable parts due to network modularity we suggest a computational approach using hybrid stochastic-deterministic optimization for the detection of perturbations in the network Jacobian using the sparsity promoting effect of [Formula: see text]-penalization. Our approach is illustrated by means of published metabolomic and signaling reaction networks. PMID:23708492

Kügler, Philipp; Yang, Wei

2014-06-01

82

Improvement to the averaging method using the Jacobian elliptic function

The averaging method was improved by using the Jacobian elliptic sine (sn), cosine (cn) and delta (dn) functions as generating solutions in order to obtain a highly accurate periodic solution for a strongly nonlinear dynamical system. The proposed method can be applied to a relatively general nonlinear system based on the single degree-of-freedom Duffing equation. Two methods of stability analysis

T. Okabe; T. Kondou

2009-01-01

83

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

84

Torsion Points on the Fermat Curves and Their Jacobians.

National Technical Information Service (NTIS)

Let p be a prime greater than 3 and not equal to 7, and let K be the cyclotomic field obtained by adjoining a primitive p-th root of 1 to the rational numbers. We compute the image of the K-rational torsion part of the Mordell-Weil group of the Jacobian o...

P. Tzermias

1996-01-01

85

Fast computation of complete elliptic integrals and Jacobian elliptic functions

As a preparation step to compute Jacobian elliptic functions efficiently, we created a fast method to calculate the complete\\u000a elliptic integral of the first and second kinds, K(m) and E(m), for the standard domain of the elliptic parameter, 0 m m < 0.9, the method utilizes 10 pairs of approximate polynomials of the order of 9–19 obtained by truncating Taylor series

Toshio Fukushima

2009-01-01

86

The a-numbers of Jacobians of Suzuki curves

For $m \\\\in {\\\\mathbb N}$, let $S_m$ be the Suzuki curve defined over ${\\\\mathbb F}_{2^{2m+1}}$. It is well-known that $S_m$ is supersingular, but the p-torsion group scheme of its Jacobian is not known. The a-number is an invariant of the isomorphism class of the p-torsion group scheme. In this paper, we compute a closed formula for the a-number of $S_m$

Holley Friedlander; Derek Garton; Beth Malmskog; Rachel Pries; Colin Weir

2011-01-01

87

Direct EIT Jacobian calculations for conductivity change and electrode movement.

Electrical impedance tomography (EIT) is very sensitive to deformations of the medium boundary shape. For lung imaging, breathing and changes in posture move the electrodes and change the chest shape, resulting in image artefacts. Several approaches have been proposed to improve the reconstructed images; most methods reconstruct both the boundary deformation and conductivity change from the measured data. These techniques require the calculation of the 'movement Jacobian', reflecting measurement changes due to the boundary deformation. Previous papers have calculated this Jacobian using perturbation techniques, which are slow (requiring multiple solutions of the forward problem) and become inaccurate with increasing finite element model size. This effect has limited reconstruction algorithms for deformable media to mostly 2D. To address this problem, we propose a direct method to calculate the Jacobian, based on a formulation of the derivatives of the finite element system matrix with respect to geometry changes. An illustrative example of these calculations is given, as well as a comparison between the proposed method and a perturbation method. Results show this method is approximately 300 times faster; and for larger model sizes, the perturbation method begins to diverge from those from the direct method proposed. PMID:18544810

Gómez-Laberge, Camille; Adler, Andy

2008-06-01

88

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

89

Jacobian-free Newton–Krylov methods: a survey of approaches and applications

Jacobian-free Newton–Krylov (JFNK) methods are synergistic combinations of Newton-type methods for superlinearly convergent solution of nonlinear equations and Krylov subspace methods for solving the Newton correction equations. The link between the two methods is the Jacobian-vector product, which may be probed approximately without forming and storing the elements of the true Jacobian, through a variety of means. Various approximations to

D. A. Knoll; D. E. Keyes

2004-01-01

90

Jacobian-free Newton-Krylov methods: a survey of approaches and applications

Jacobian-free Newton-Krylov (JFNK) methods are synergistic combinations of Newton-type methods for super- linearly convergent solution of nonlinear equations and Krylov subspace methods for solving the Newton correction equations. The link between the two methods is the Jacobian-vector product, which may be probed approximately without forming and storing the elements of the true Jacobian, through a variety of means. Various approximations

D. A. Knoll; D. E. Keyes

2004-01-01

91

NASA Astrophysics Data System (ADS)

Modeling large multicomponent reactive transport systems in porous media is particularly challenging when the governing partial differential algebraic equations (PDAEs) are highly nonlinear and tightly coupled due to complex nonlinear reactions and strong solution-media interactions. Here we present a preconditioned Jacobian-Free Newton-Krylov (JFNK) solution approach to solve the governing PDAEs in a fully coupled and fully implicit manner. A well-known advantage of the JFNK method is that it does not require explicitly computing and storing the Jacobian matrix during Newton nonlinear iterations. Our approach further enhances the JFNK method by utilizing physics-based, block preconditioning and a multigrid algorithm for efficient inversion of the preconditioner. This preconditioning strategy accounts for self- and optionally, cross-coupling between primary variables using diagonal and off-diagonal blocks of an approximate Jacobian, respectively. Numerical results are presented demonstrating the efficiency and massive scalability of the solution strategy for reactive transport problems involving strong solution-mineral interactions and fast kinetics. We found that the physics-based, block preconditioner significantly decreases the number of linear iterations, directly reducing computational cost; and the strongly scalable algebraic multigrid algorithm for approximate inversion of the preconditioner leads to excellent parallel scaling performance.

Guo, Luanjing; Huang, Hai; Gaston, Derek R.; Permann, Cody J.; Andrs, David; Redden, George D.; Lu, Chuan; Fox, Don T.; Fujita, Yoshiko

2013-03-01

92

Modeling large multicomponent reactive transport systems in porous media is particularly challenging when the governing partial differential algebraic equations (PDAEs) are highly nonlinear and tightly coupled due to complex nonlinear reactions and strong solution-media interactions. Here we present a preconditioned Jacobian-Free Newton-Krylov (JFNK) solution approach to solve the governing PDAEs in a fully coupled and fully implicit manner. A well-known advantage of the JFNK method is that it does not require explicitly computing and storing the Jacobian matrix during Newton nonlinear iterations. Our approach further enhances the JFNK method by utilizing physics-based, block preconditioning and a multigrid algorithm for efficient inversion of the preconditioner. This preconditioning strategy accounts for self- and optionally, cross-coupling between primary variables using diagonal and off-diagonal blocks of an approximate Jacobian, respectively. Numerical results are presented demonstrating the efficiency and massive scalability of the solution strategy for reactive transport problems involving strong solution-mineral interactions and fast kinetics. We found that the physics-based, block preconditioner significantly decreases the number of linear iterations, directly reducing computational cost; and the strongly scalable algebraic multigrid algorithm for approximate inversion of the preconditioner leads to excellent parallel scaling performance.

Luanjing Guo; Hai Huang; Derek Gaston; Cody Permann; David Andrs; George Redden; Chuan Lu; Don Fox; Yoshiko Fujita

2013-03-01

93

ANFIS Based-Kinematic Modeling of Mobile Parallel Robot

This paper considers a kinematic based ANFIS motion modeling and control of a mobile parallel robot (MPR), consist of a multi-degree of freedom (DOF) parallel manipulator and a mobile platform. First, kinematics modeling for the hybrid structure is derived. Then singularities of the MPR structure are identified. Taking the self motion into consideration due to the redundancy, the inverse kinematic

Amar Khoukhi; Mutaz Hamdan; Fouad Al-Sunni

2012-01-01

94

Endomorphism rings of certain Jacobians in finite characteristic

We prove that, under certain additional assumptions, the endomorphism ring of the Jacobian of a curve y{sup l}=f(x) contains a maximal commutative subring isomorphic to the ring of algebraic integers of the lth cyclotomic field. Here l is an odd prime dividing the degree n of the polynomial f and different from the characteristic of the algebraically closed ground field; moreover, n{>=}9. The additional assumptions stipulate that all coefficients of f lie in some subfield K over which its (the polynomial's) Galois group coincides with either the full symmetric group S{sub n} or with the alternating group A{sub n}.

Zarkhin, Yu G [Institute of Mathematical Problems of Biology, Russian Academy of Sciences, Pushchino, Moscow region (Russian Federation)

2002-08-31

95

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

96

We have determined high-resolution hypocenters for 45,000+ earthquakes that occurred between 1980 and 2000 in the Long Valley caldera area using a double-difference earthquake location algorithm and routinely determined arrival times. The locations reveal numerous discrete fault planes in the southern caldera and adjacent Sierra Nevada block (SNB). Intracaldera faults include a series of east/west-striking right-lateral strike-slip faults beneath the caldera's south moat and a series of more northerly striking strike-slip/normal faults beneath the caldera's resurgent dome. Seismicity in the SNB south of the caldera is confined to a crustal block bounded on the west by an east-dipping oblique normal fault and on the east by the Hilton Creek fault. Two NE-striking left-lateral strike-slip faults are responsible for most seismicity within this block. To understand better the stresses driving seismicity, we performed stress inversions using focal mechanisms with 50 or more first motions. This analysis reveals that the least principal stress direction systematically rotates across the studied region, from NE to SW in the caldera's south moat to WNW-ESE in Round Valley, 25 km to the SE. Because WNW-ESE extension is characteristic of the western boundary of the Basin and Range province, caldera area stresses appear to be locally perturbed. This stress perturbation does not seem to result from magma chamber inflation but may be related to the significant (???20 km) left step in the locus of extension along the Sierra Nevada/Basin and Range province boundary. This implies that regional-scale tectonic processes are driving seismic deformation in the Long Valley caldera.

Prejean, S.; Ellsworth, W.; Zoback, M.; Waldhauser, F.

2002-01-01

97

Abstract—Maps of local tissue compression or expansion are often computed by comparing magnetic resonance imaging (MRI) scans using nonlinear image registration. The resulting changes are commonly analyzed using tensor-based morphometry to make inferences about anatomical differences, often based on the Jacobian map, which estimates local tissue gain or loss. Here, we provide rigorous mathematical analyses of the Jacobian maps, and

Alex D. Leow; Igor Yanovsky; Ming-chang Chiang; Agatha D. Lee; Andrea D. Klunder; Allen Lu; James T. Becker; Simon W. Davis; Arthur W. Toga; Paul M. Thompson

2007-01-01

98

Effects of the Jacobian evaluation on Newton's solution of the Euler equations

Newton's method is developed for solving the 2-D Euler equations. The Euler equations are discretized using a finite-volume method with upwind flux splitting schemes. Both analytical and numerical methods are used for Jacobian calculations. Although the numerical method has the advantage of keeping the Jacobian consistent with the numerical residual vector and avoiding extremely complex analytical differentiations, it may have

O. Onur; S. Eyi

2005-01-01

99

Systems of multicomponent reactive transport in porous media that are large, highly nonlinear, and tightly coupled due to complex nonlinear reactions and strong solution-media interactions are often described by a system of coupled nonlinear partial differential algebraic equations (PDAEs). A preconditioned Jacobian-Free Newton-Krylov (JFNK) solution approach is applied to solve the PDAEs in a fully coupled, fully implicit manner. The advantage of the JFNK method is that it avoids explicitly computing and storing the Jacobian matrix during Newton nonlinear iterations for computational efficiency considerations. This solution approach is also enhanced by physics-based blocking preconditioning and multigrid algorithm for efficient inversion of preconditioners. Based on the solution approach, we have developed a reactive transport simulator named RAT. Numerical results are presented to demonstrate the efficiency and massive scalability of the simulator for reactive transport problems involving strong solution-mineral interactions and fast kinetics. It has been applied to study the highly nonlinearly coupled reactive transport system of a promising in situ environmental remediation that involves urea hydrolysis and calcium carbonate precipitation.

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

2012-06-01

100

Anisotropic resistivity inversion

NASA Astrophysics Data System (ADS)

We present an inversion method for 3D electrical imaging in media with an inhomogeneous and anisotropic conductivity distribution. The conductivity distribution is discretized via finite elements and is described by a second-order tensor at each finite element node. The inversion method is formulated as a functional optimization with an error functional containing terms measuring data misfit and model covariance by means of smoothness, anisotropy and deviation from a starting model. Including the model covariance information overcomes the problem of ill-posedness at the expense of limiting the allowed models to the class of models which are compatible with the provided model covariance information. The discretized form of the error functional is minimized by a Levenberg-Marquardt type method using an iterative preconditioned conjugate gradient solver. The use of an iterative solver allows one to bypass the actual computation of the Jacobian or an inverse system matrix. The use of a memory efficient iterative solver together with the implementation on parallel computers allows large-scale inverse problems, comprising several hundred thousand nodes with hundreds of sources and receivers, to be solved. The new method is tested using computer-generated data from two- and three-dimensional synthetic models. For each inversion a choice of penalty parameters, gauging the level of model covariance information imposed, has to be made and the level of regularization required is hard to estimate. We find that running a suite of inversions with varying penalty parameters and subsequent examination of the results (including inspection of residual maps) offers a viable method for choosing appropriate numerical values for the penalty levels. In the applications we found the inversion process to be highly non-linear. Inversion models from intermediate steps of the iterative inversion show structure in places that do not exhibit structure in the true model and only at later iterations do anomalies move to the correct location in the modelling domain. This result indicates that linearized inversions that fail to re-linearize during the inversion process will fail to find meaningful inversion images. The inversion images achieved using the new method recover the important features of the true models, including the approximate magnitudes of the conductivity anomalies and the magnitudes and directions of anisotropy anomalies. The inversion images are generally 'blurred', that is sharp edges are smoothed, and the recovered magnitudes of conductivity, anisotropy and anisotropy direction are generally under-estimated.

Pain, Christopher C.; Herwanger, Jörg V.; Saunders, Jonathan H.; Worthington, Michael H.; de Oliveira, Cassiano R. E.

2003-10-01

101

Solving Nonlinear Solid Mechanics Problems with the Jacobian-Free Newton Krylov Method

The solution of the equations governing solid mechanics is often obtained via Newton's method. This approach can be problematic if the determination, storage, or solution cost associated with the Jacobian is high. These challenges are magnified for multiphysics applications with many coupled variables. Jacobian-free Newton-Krylov (JFNK) methods avoid many of the difficulties associated with the Jacobian by using a finite difference approximation. BISON is a parallel, object-oriented, nonlinear solid mechanics and multiphysics application that leverages JFNK methods. We overview JFNK, outline the capabilities of BISON, and demonstrate the effectiveness of JFNK for solid mechanics and solid mechanics coupled to other PDEs using a series of demonstration problems.

J. D. Hales; S. R. Novascone; R. L. Williamson; D. R. Gaston; M. R. Tonks

2012-06-01

102

Real-Time Inverse Kinematics for Humans.

National Technical Information Service (NTIS)

A general methodology and associated computational algorithm for predicting realistic postures of digital humans (mannequins) is presented. The basic plot for this effort is a task-based approach, where we believe that humans assume different postures for...

J. Mun J. Yang K. Abdel-Malek K. Nebel Z. Mi

2004-01-01

103

We illustrate in some detail a 2D inverse-equilibrium solver that was constructed to analyze tokamak configurations and stellarators (the latter in the context of the average method). To ensure that the method is suitable not only to determine equilibria, but also to provide appropriately represented data for existing stability codes, it is important to be able to control the Jacobian, tilde J is identical to delta(R,Z)/delta(rho, theta). The form chosen is tilde J = J/sub 0/(rho)R/sup l/rho where rho is a flux surface label, and l is an integer. The initial implementation is for a fixed conducting-wall boundary, but the technique can be extended to a free-boundary model.

Hicks, H.R.; Dory, R.A.; Holmes, J.A.

1983-01-01

104

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

105

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

106

Fully-implicit Jacobian-free Newton-Krylov Solvers for the nonhydrostatic Euler equations

For most atmospheric flows, gravity and acoustic waves are the fastest waves in the system. These fast waves severely restrict the time-step in the explicit integration of the non-hydrostatic compressible Euler equations. To circumvent this problem, a fully-implicit time-integrator is proposed using the Jacobian-Free Newton Krylov (JFNK) framework. Since forming and storing the Jacobian matrix is computationally expensive, JFNK methods

J. F. Kelly; F. Giraldo; L. Carr

2009-01-01

107

Gray matter atrophy provides important insights into neurodegeneration in multiple sclerosis (MS) and can be used as a marker of neuroprotection in clinical trials. Jacobian integration is a method for measuring volume change that uses integration of the local Jacobian determinants of the nonlinear deformation field registering two images, and is a promising tool for measuring gray matter atrophy. Our main objective was to compare the statistical power of the Jacobian integration method to commonly used methods in terms of the sample size required to detect a treatment effect on gray matter atrophy. We used multi-center longitudinal data from relapsing–remitting MS patients and evaluated combinations of cross-sectional and longitudinal pre-processing with SIENAX/FSL, SPM, and FreeSurfer, as well as the Jacobian integration method. The Jacobian integration method outperformed these other commonly used methods, reducing the required sample size by a factor of 4–5. The results demonstrate the advantage of using the Jacobian integration method to assess neuroprotection in MS clinical trials.

Nakamura, Kunio; Guizard, Nicolas; Fonov, Vladimir S.; Narayanan, Sridar; Collins, D. Louis; Arnold, Douglas L.

2013-01-01

108

A Constrained Multibody System Dynamics Avoiding Kinematic Singularities

NASA Astrophysics Data System (ADS)

In the analysis of constrained multibody systems, the constraint reaction forces are normally expressed in terms of the constraint equations and a vector of Lagrange multipliers. Because it fails to incorporate conservation of momentum, the Lagrange multiplier method is deficient when the constraint Jacobian matrix is singular. This paper presents an improved dynamic formulation for the constrained multibody system. In our formulation, the kinematic constraints are still formulated in terms of the joint constraint reaction forces and moments; however, the formulations are based on a second-order Taylor expansion so as to incorporate the rigid body velocities. Conservation of momentum is included explicitly in this method; hence the problems caused by kinematic singularities can be avoided. In addition, the dynamic formulation is general and applicable to most dynamic analyses. Finally the 3-leg Stewart platform is used for the example of analysis.

Huang, Chih-Fang; Yan, Chang-Dau; Jeng, Shyr-Long; Cheing, Wei-Hua

109

Magnetotelluric inversion via reverse time migration algorithm of seismic data

We propose a new algorithm for two-dimensional magnetotelluric (MT) inversion. Our algorithm is an MT inversion based on the steepest descent method, borrowed from the backpropagation technique of seismic inversion or reverse time migration, introduced in the middle 1980s by Lailly and Tarantola. The steepest descent direction can be calculated efficiently by using the symmetry of numerical Green's function derived from a mixed finite element method proposed by Nedelec for Maxwell's equation, without calculating the Jacobian matrix explicitly. We construct three different objective functions by taking the logarithm of the complex apparent resistivity as introduced in the recent waveform inversion algorithm by Shin and Min. These objective functions can be naturally separated into amplitude inversion, phase inversion and simultaneous inversion. We demonstrate our algorithm by showing three inversion results for synthetic data.

Ha, Taeyoung [Department of Mathematical Sciences, Seoul National University, San 56-1, Sillim-dong, Gwanak-gu, Seoul 151-747 (Korea, Republic of)]. E-mail: tyha@math.snu.ac.kr; Shin, Changsoo [School of Civil, Urban and Geosystem Engineering, Seoul National University, San 56-1, Sillim-dong, Gwanak-gu, Seoul 151-742 (Korea, Republic of)]. E-mail: css@model.snu.ac.kr

2007-07-01

110

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

111

Fast algorithm for kinematics problems solving of the low-cost legged robot LEROI

The objective of this paper is to present the fast and easy implemented algorithm for solving the forward and inverse kinematics of a low-cost 6 DOF biped robot LEROI, developed in the Robotics Lab of the University Carlos III of Madrid. To solve the inverse kinematics, the robot motion is divided in five different phases, which are connected in appropriate

P. Staroverov; M. Arbulu; C. Balaguer

112

In this paper a method to solve the trajectory generation problem in redundant degree of freedom manipulator has been proposed, and the variational approach within the B-spline function are introduced for minimization of the consumed electrical energy of a robot manipulator system. In the proposed method, the inverse matrix of Jacobian calculation is not required, and the minimal trajectory error

Andre R. Hirakawa; Atsuo Kawamura

1997-01-01

113

Inverse methods are useful tools not only for deriving estimates of unknown parameters of the subsurface, but also for appraisal of the thus obtained models. While not being neither the most general nor the most efficient methods, Bayesian inversion based on the calculation of the Jacobian of a given forward model can be used to evaluate many quantities useful in

V. Rath; A. Wolf; H. M. Bücker

2006-01-01

114

Hologram interferometry of vibrations represented by the square of a Jacobian elliptic function

The paper deals with the evaluation of fringe irradiance distribution in time-averaged holographic interferometry of periodic, non-sinusoidal vibrations represented by the square of a Jacobian elliptic function. Analysis has been performed by considering the effect of motion on coherence. The techniques of holographic addition and substraction have been applied to extend the amplitude measurement range. Graphical representation of the fringe

P. C. Gupta; K. Singh

1976-01-01

115

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

116

NASA Astrophysics Data System (ADS)

Using the integral field unit DensePak on the WIYN 3.5 m telescope we have obtained H? velocity fields of 39 nearly face-on disks at echelle resolutions. High-quality, uniform kinematic data and a new modeling technique enabled us to derive accurate and precise kinematic inclinations with mean i kin = 23° for 90% of these galaxies. Modeling the kinematic data as single, inclined disks in circular rotation improves upon the traditional tilted-ring method. We measure kinematic inclinations with a precision in sin i of 25% at 20° and 6% at 30°. Kinematic inclinations are consistent with photometric and inverse Tully-Fisher inclinations when the sample is culled of galaxies with kinematic asymmetries, for which we give two specific prescriptions. Kinematic inclinations can therefore be used in statistical "face-on" Tully-Fisher studies. A weighted combination of multiple, independent inclination measurements yield the most precise and accurate inclination. Combining inverse Tully-Fisher inclinations with kinematic inclinations yields joint probability inclinations with a precision in sin i of 10% at 15° and 5% at 30°. This level of precision makes accurate mass decompositions of galaxies possible even at low inclination. We find scaling relations between rotation speed and disk-scale length identical to results from more inclined samples. We also observe the trend of more steeply rising rotation curves with increased rotation speed and light concentration. This trend appears to be uncorrelated with disk surface brightness.

Andersen, David R.; Bershady, Matthew A.

2013-05-01

117

Augmented kinematic feedback system

NASA Astrophysics Data System (ADS)

This paper discusses a real-time augmented kinematic feedback system which can be used as a diagnosis tool for individuals with motor disabilities. The system captures and analyzes movement via color targets attached to an individual and then feeds back information about movement kinematics. This target tracking approach has a high potential for achieving a real- time kinematic assessment capability. The approach recognizes distinct moving colored targets using video data. Multiple colored targets are attached to an individual at strategic locations and then target movement is tracked using a video data acquisition system. The ability to track and assess movement in real-time allows researchers and practitioners to better study and potentially treat various motor disabilities. Recent research has suggested that kinematic feedback can enhance motor recovery of disabled individuals. This approach addresses the need for a real-time measure of human movement and discusses using kinematic feedback to enhance disability recovery.

Andert, Ed P.; Archipley-Smith, Donna K.

1994-07-01

118

Kinematic Jump Processes For Monocular 3D Human Tracking

A major difficulty for 3D human body tracking from monocular image sequences is the near non-observability of kinematic degrees of freedom that generate motion in depth. For known link (body seg- ment) lengths, the strict non-observabilities reduce to twofold 'for- wards\\/backwards flipping' ambiguities for each link. These imply # links formal inverse kinematics solutions for the full model, and hence

Cristian Sminchisescu; Bill Triggs

2003-01-01

119

NASA Astrophysics Data System (ADS)

A Jacobian-free variable-stepsize method is developed for the numerical integration of the large, stiff systems of differential equations encountered when simulating transport in heterogeneous porous media. Our method utilises the exponential Rosenbrock-Euler method, which is explicit in nature and requires a matrix-vector product involving the exponential of the Jacobian matrix at each step of the integration process. These products can be approximated using Krylov subspace methods, which permit a large integration stepsize to be utilised without having to precondition the iterations. This means that our method is truly "Jacobian-free" - the Jacobian need never be formed or factored during the simulation. We assess the performance of the new algorithm for simulating the drying of softwood. Numerical experiments conducted for both low and high temperature drying demonstrates that the new approach outperforms (in terms of accuracy and efficiency) existing simulation codes that utilise the backward Euler method via a preconditioned Newton-Krylov strategy.

Carr, E. J.; Turner, I. W.; Perré, P.

2013-01-01

120

NASA Astrophysics Data System (ADS)

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

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

121

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

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

122

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

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

123

Algebraic geometrical solutions of a new shallow-water equation and Dym- type equation are studied in connection with Hamiltonian flows on nonlinear subvarieties of hyperelliptic Jacobians. These equations belong to a class of N-component integrable systems generated by Lax equations with energy- dependent Schr¨ odinger operators having poles in the spectral parameter. The classes of quasi-periodic and soliton-type solutions of these

Mark S Alber; Yuri N Fedorov

124

Modern multicomponent geochemical transport models require the use of parallel computation for carrying out three-dimensional, field-scale simulations due to extreme memory and processing demands. However, to fully exploit the advanced computational power provided by today's supercomputers, innovative parallel algorithms are needed. We demonstrate the use of Jacobian-free Newton Krylov (JFNK) within the Newton Raphson method to reduce memory and processing

G. E. Hammond; A. J. Valocchi; P. C. Lichtner

2005-01-01

125

A Jacobian-free Newton–Krylov algorithm for compressible turbulent fluid flows

Despite becoming increasingly popular in many branches of computational physics, Jacobian-free Newton–Krylov (JFNK) methods have not become the approach of choice in the solution of the compressible Navier–Stokes equations for turbulent aerodynamic flows. To a degree, this is related to some subtle aspects of JFNK methods that are not well understood, and, if poorly handled, can lead to inefficient and

Todd T. Chisholm; David W. Zingg

2009-01-01

126

Modern multicomponent geochemical transport models require the use of parallel computation for carrying out three-dimensional, field-scale simulations due to extreme memory and processing demands. However, to fully exploit the advanced computational power provided by today’s supercomputers, innovative parallel algorithms are needed. We demonstrate the use of Jacobian-free Newton–Krylov (JFNK) within the Newton–Raphson method to reduce memory and processing requirements on

G. E. Hammond; A. J. Valocchi; P. C. Lichtner

2005-01-01

127

Regularity of mappings inverse to Sobolev mappings

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

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

2012-10-31

128

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

129

NASA Astrophysics Data System (ADS)

Multicomponent reactive transport in porous media is a tightly coupled multiphysics problem often described by a system of coupled nonlinear partial differential algebraic equations (PDAEs). For reactive transport systems that are large, highly nonlinear, and tightly coupled due to complex reactions and strong solution-mineral interactions, a preconditioned Jacobian-free Newton-Krylov (JFNK) solution approach is applied to solve the PDAEs in a fully coupled, fully implicit manner. The advantage of the JFNK method is that it avoids explicit computation and storage of the Jacobian matrix during Newton nonlinear iterations, which is highly desirable for efficient solution of large reactive transport problems. This approach is also enhanced by a physics-based blocking approach for constructing the preconditioner and multigrid algorithm for efficient inversion of preconditioners. The preconditioning strategy can account for both inter-cell transport-reaction self-coupling by using the diagonal blocks of the approximate Jacobian and the additional intra-cell transport-reaction cross-coupling through off-diagonal blocks at minimal additional computational cost. Numerical results are presented to demonstrate the efficiency and massive scalability of the solution strategy for reactive transport problems involving strong solution-mineral interactions and fast kinetics. This approach has been applied to two reactive transport systems involving induced mineral precipitation. In the first system, calcite precipitation takes place as a result of the combination of injected calcium and ureolysis-produced bicarbonate ions.. In the other system, separate solutions containing calcium and bicarbonate ions are introduced into the porous medium in a parallel injection format such that calcium carbonate mineral precipitates in the mixing zone formed between the two fluids. Highly nonlinear coupling effects of fluid flow, transport, kinetic and equilibrium reactions, and changes in media properties are investigated by using the preconditioned JFNK solution approach for both systems. The numerical simulation results are compared to laboratory experiment results, and the comparison demonstrates that the fully-coupled, fully-implicit solutions can capture the transient events and sharp chemical gradients characteristic of the system, including the changes in flow properties caused by mineral precipitation and/or dissolution.

Guo, L.; Huang, H.; Gaston, D.; Redden, G. D.; Permann, C.; Andrs, D.; Fox, D. T.; Fujita, Y.; Lu, C.

2011-12-01

130

NASA Astrophysics Data System (ADS)

Swashplate mechanism is the steering control mechanism used in most helicopters. It is a complex multi-loop closed kinematic chain which controls the angles of attack of the main rotor blades. In most new model helicopters, this mechanism is also equipped with the bell-hiller stabilizer bar (flybar), to improve the stability. This paper aimed at the kinematic analysis of one of the latest architectures of the swashplate mechanism, used for hingeless rotor with the flybar. Hence, the position analysis of each module and whole mechanism, based on parallel manipulators concept with more details involved than other works, was presented here. The kinematic model was further developed to obtain Jacobian matrices, velocity and acceleration analysis in detail. Finally, a particular example was conducted and compared with an ADAMS rigid body dynamic model, to verify the analytical model. In many simulated cases, the results matched.

Sabaapour, Mohammad Reza; Zohoor, Hassan

131

3D Kinematic Simulation for PA10-7C Robot Arm Based on VRML

In this paper, a graphical, flexible, interactive, and systematic 3D simulation helps facilitate analyzing and previewing kinematics of PA10-7C robot arm in terms of forward kinematics, inverse kinematics, and the Denavit-Hartenberg convention. Modeling and control are of critical importance when the robot arm is used for practical applications. In the paper, the D-H model of PA10-7C robot arm is given

Weimin Shen; Jason Gu; Yide Ma

2007-01-01

132

Kinematic synthesis of bevel-gear-type robotic wrist mechanisms

NASA Astrophysics Data System (ADS)

Bevel-gear-type robotic wrist mechanisms are commonly used in industry. The reasons for their popularity are that they are compact, light-weight, and relatively inexpensive. However, there are singularities in their workspace, which substantially degrade their manipulative performance. The objective of this research is to develop an atlas of three-degree-of-freedom bevel-gear-type wrist mechanisms, and through dimensional synthesis to improve their kinematic performance. The dissertation contains two major parts: the first is structural analysis and synthesis, the other is kinematic analysis and dimensional synthesis. To synthesize the kinematic structures of bevel-gear-type wrist mechanisms, the kinematic structures are separated from their functional considerations. All kinematic structures which satisfy the mobility condition are enumerated in an unbiased, systematic manner. Then the bevel-gear-type wrist mechanisms are identified by applying the functional requirements. Structural analysis shows that a three-degree-of-freedom wrist mechanism usually consists of non-fractionated, two degree-of-freedom epicyclic gear train jointed with the base link. Therefore, the structural synthesis can be simplified into a problem of examining the atlas of non-fractionated, two-degree-of-freedom epicyclic gear trains. The resulting bevel-gear-type wrist mechanism has been categorized and evaluated. It is shown that three-degree-of-freedom, four-jointed wrist mechanisms are promising for further improving the kinematic performance. It is found that a spherical planetary gear train is necessarily imbedded in a three-degree-of-freedom, four-jointed wrist mechanism. Therefore, to study the workspace and singularity problems of three-degree-of-freedom four-jointed spherical wrist mechanisms, we have to study the trajectories of spherical planetary gear trains. The parametric equations of the trajectories and some useful geometric properties for the analysis and synthesis of workplace are derived. The workspace boundary equations can be derived via both geometric consideration and Jacobian analysis. The workspace is divided by inner and outer boundaries into regions of accessibility of zero, two, and four. The design criteria of full workspace and a maximum four-root region are established.

Lin, Chen-Chou

133

Kinematic modeling for feedback control of an omnidirectional wheeled mobile robot

We have introduced a methodology for the kinematic modeling of wheeled mobile robots. In this paper, we apply our methodology to Uranus, an omnidirectional wheeled mobile robot which is being developed in the Robotics Institute of Carnegie Mellon University. We assign coordinate systems to specify the transformation matrices and write the kinematic equations-of-motion. We illustrate the actuated inverse and sensed

P. Muir; C. Neuman

1987-01-01

134

Kinematical model and control architecture for a human inspired five DOF robotic leg

This paper describes the theoretical aspects that aimed the realization of an anthropometric robotic leg. It contains a brief overview of the mechanical structure and an accurate description of the prototype kinematical behavior. In particular, two different numerical methods for solving the kinematical inversion process are described in details. Moreover, the aim of this project is the development of new

G. Muscato; G. Spampinato

2007-01-01

135

Exact Jacobians in an implicit Newton method for two-phase flow in porous media

NASA Astrophysics Data System (ADS)

Geological storage of CO2 is one option for mitigating the effects of CO2 emissions on global warming. Since extensive on-site monitoring of the CO2 plume propagation is expensive, numerical simulations are an attractive alternative for gaining deeper insight in the dynamics of this system. We consider a model for two-phase flow in porous media for representing the injection stage of a CO2 sequestration scenario, when the plume propagation is dominated by advection. The porous medium filled by the two phases CO2 and brine is modelled as an initial-boundary-value problem consisting of two nonlinear, coupled partial differential equations, which are complemented by appropriate boundary and initial conditions. We present a new numerical approach to solve this fully coupled system using exact Jacobians. The method is based on the finite element, finite volume, box method [Huber & Helmig(2000)] for the space discretization and, since stability of the method is one of the main concerns, the fully implicit Euler method for the time discretization. A simple first order upwind method takes into account advective contributions. The resulting system of nonlinear algebraic equations is linearized by Newton's method. The required Jacobians can be obtained elegantly by automatic differentiation (AD) [Griewank & Walther(2008), Rall(1981)], a source code transformation giving exact derivatives of the discretized equations with respect to primary variables. The resulting system of linear equations is then solved by an iterative method (BiCGStab) with ILU0 preconditioning in every Newton step. We compare the forward AD differentiation mode to the standard finite difference method in terms of precision and performance. It turns out that AD performs favourable in both aspects. We also illustrate the advantages of exact Jacobians for two-phase flow in a sequestration scenario investigating the evolution of pressure and saturation.

Büsing, H.; Clauser, C.

2012-04-01

136

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

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

Ruf, A.; Horaud, R.

1999-11-01

137

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

We present a new approach for the $k$--eigenvalue problem using a combination of classical power iteration and the Jacobian--free Newton--Krylov method (JFNK). The method poses the $k$--eigenvalue problem as a fully coupled nonlinear system, which is solved by JFNK with an effective block preconditioning consisting of the power iteration and algebraic multigrid. We demonstrate effectiveness and algorithmic scalability of the method on a 1-D, one group problem and two 2-D two group problems and provide comparison to other efforts using silmilar algorithmic approaches.

Dana Knoll; HyeongKae Park; Chris Newman

2011-02-01

138

Simulating soft tissues in real time is a significant challenge since a compromise between biomechanical accuracy and computational efficiency must be found. In this paper, we propose a new discretization method, the Multiplicative Jacobian Energy Decomposition (MJED) which is an alternative to the classical Galerkin FEM (Finite Element Method) formulation. This method for discretizing non-linear hyperelastic materials on linear tetrahedral meshes leads to faster stiffness matrix assembly for a large variety of isotropic and anisotropic materials. We show that our new approach, implemented within an implicit time integration scheme, can lead to fast and realistic liver deformations including hyperelasticity, porosity and viscosity. PMID:20879236

Marchesseau, Stéphanie; Heimann, Tobias; Chatelin, Simon; Willinger, Rémy; Delingette, Hervé

2010-01-01

139

Compactified Strings as Quantum Statistical Partition Function on the Jacobian Torus

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

140

Three tooth kinematic coupling

A three tooth kinematic coupling based on having three theoretical line contacts formed by mating teeth rather than six theoretical point contacts. The geometry requires one coupling half to have curved teeth and the other coupling half to have flat teeth. Each coupling half has a relieved center portion which does not effect the kinematics, but in the limit as the face width approaches zero, three line contacts become six point contacts. As a result of having line contact, a three tooth coupling has greater load capacity and stiffness. The kinematic coupling has application for use in precision fixturing for tools or workpieces, and as a registration device for a work or tool changer or for optics in various products.

Hale, Layton C. (Livermore, CA)

2000-01-01

141

Kinematics: Speed, Velocity & Acceleration

NSDL National Science Digital Library

The following resource is a NFL sponsored, National Science Foundation funded program intended to teach students about scientific concepts by using the popular sport of Football. Each lesson is accompanied by an informative and fast paced video. In this lesson, students will explore kinematics on the playing field. NSF-funded scientists Tony Schmitz from the University of Florida and John Ziegert of Clemson University explain how the kinematic concepts of position, velocity and acceleration can be used to define how a running back moves.

2010-01-01

142

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

143

NASA Astrophysics Data System (ADS)

An 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. ALOS PALSAR coseismic pairs have been processed for eight ascending paths to both interferograms and SAR pixel offsets. Along-track (azimuth) coseismic pixel offsets have large amplitude ripples or waves that are likely due to the ionosphere, and the interferograms show waves in the phase that also are likely due to the ionospheric disturbances that seem to affect the Sichuan area in May and June 2008. Envisat ASAR acquired a number of scenes in Sichuan after the earthquake in high-resolution strip-map modes. Unfortunately, only four descending tracks had prequake acquisitions that allow InSAR analysis, and available temporal and spatial baselines were not optimal. ScanSAR ASAR acquisitions (wide-swath, WS mode) were acquired on tracks that have a number of pre-quake acquisitions, but InSAR coherence at C-band wavelength is marginal for the WS-WS interferograms and adequate only in the plains for the strip-map interferograms. Slip models for the earthquake have been estimated using a joint inversion of the eight PALSAR and four ASAR strip-map interferograms with GPS data published by the Crustal Motion Observation Network of China and teleseismic data. The models show that most of the slip occurred in the upper 10 km of the fault zone. SAR pixel offsets show at least two major faults ruptured. Interferograms and SAR pixel offset measurements show a surface rupture with up to 6 m of oblique right-lateral and thrust slip on a complex set of faults close to what has been called the Beichuan Fault that passes close to the devastated Beichuan. These are consistent with field measurements made by several groups. To the southwest of Beichuan, a second fault to the east of the Beichuan Fault, the Hanwang Fault, a segment of the Pengguan Fault system had significant slip with primarily thrust motion, consistent with field mapping of up to 2 m of vertical displacement. We calculated viscoelastic models of predicted postseismic deformation in the first year after the earthquake using our coseismic static slip model. Projecting into the radar lines of sight yields a prediction for interferometric measurements in the range of 4-6 cm peak to peak. Postseismic interferograms from PALSAR and Envisat ASAR show some indications of the deformation after the earthquake. Large InSAR phase errors due to the propagation through the atmosphere (caused primarily by tropospheric water vapor, but also ionospheric variations for PALSAR) in addition to low coherence in the steep Longmen Shan make it difficult to unambiguously measure the postseismic deformation. The interferograms provide high spatial resolution measurements, but less than optimal postseismic acquisitions cause limitations on the temporal sampling.

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

2009-12-01

144

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

NASA Astrophysics Data System (ADS)

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

Pethiyagoda, Ravindra; McCue, Scott W.; Moroney, Timothy J.; Back, Julian M.

2014-07-01

145

Fast unsteady flow computations with a Jacobian-free Newton-Krylov algorithm

NASA Astrophysics Data System (ADS)

Despite the advances in computer power and numerical algorithms over the last decades, solutions to unsteady flow problems remain computing time intensive. Especially for large Reynolds number flows, nonlinear multigrid, which is commonly used to solve the nonlinear systems of equations, converges slowly. The stiffness induced by the large aspect ratio cells and turbulence is not tackled well by this solution method. In previous work we showed that a Jacobian-free Newton-Krylov ( JFNK) algorithm, preconditioned with an approximate factorization of the Jacobian that approximately matches the target residual operator, enables a speed up of a factor of 10 compared to standard nonlinear multigrid for two-dimensional, large Reynolds number, unsteady flow computations. The goal of this paper is to demonstrate that the JFNK algorithm is also suited to tackle the stiffness induced by the maximum aspect ratio, the grid density, the physical time step and the Reynolds number. Compared to standard nonlinear multigrid, speed ups up to a factor of 25 are achieved.

Lucas, Peter; van Zuijlen, Alexander H.; Bijl, Hester

2010-12-01

146

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

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

147

ERIC Educational Resources Information Center

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

Coleman, J. J.

1982-01-01

148

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

149

Using the integral field unit DensePak on the WIYN 3.5 m telescope we have obtained H{alpha} velocity fields of 39 nearly face-on disks at echelle resolutions. High-quality, uniform kinematic data and a new modeling technique enabled us to derive accurate and precise kinematic inclinations with mean i{sub kin} = 23 Degree-Sign for 90% of these galaxies. Modeling the kinematic data as single, inclined disks in circular rotation improves upon the traditional tilted-ring method. We measure kinematic inclinations with a precision in sin i of 25% at 20 Degree-Sign and 6% at 30 Degree-Sign . Kinematic inclinations are consistent with photometric and inverse Tully-Fisher inclinations when the sample is culled of galaxies with kinematic asymmetries, for which we give two specific prescriptions. Kinematic inclinations can therefore be used in statistical ''face-on'' Tully-Fisher studies. A weighted combination of multiple, independent inclination measurements yield the most precise and accurate inclination. Combining inverse Tully-Fisher inclinations with kinematic inclinations yields joint probability inclinations with a precision in sin i of 10% at 15 Degree-Sign and 5% at 30 Degree-Sign . This level of precision makes accurate mass decompositions of galaxies possible even at low inclination. We find scaling relations between rotation speed and disk-scale length identical to results from more inclined samples. We also observe the trend of more steeply rising rotation curves with increased rotation speed and light concentration. This trend appears to be uncorrelated with disk surface brightness.

Andersen, David R. [NRC Herzberg Institute of Astrophysics, 5071 W Saanich Road, Victoria, BC V9E 2E7 (Canada); Bershady, Matthew A., E-mail: david.andersen@nrc-cnrc.gc.ca, E-mail: mab@astro.wisc.edu [Department of Astronomy, University of Wisconsin, 475 N Charter Street, Madison, WI 53706 (United States)

2013-05-01

150

Inverse Fourier Transform in the Gamma Coordinate System

This paper provides auxiliary results for our general scheme of computed tomography. In 3D parallel-beam geometry, we first demonstrate that the inverse Fourier transform in different coordinate systems leads to different reconstruction formulas and explain why the Radon formula cannot directly work with truncated projection data. Also, we introduce a gamma coordinate system, analyze its properties, compute the Jacobian of the coordinate transform, and define weight functions for the inverse Fourier transform assuming a simple scanning model. Then, we generate Orlov's theorem and a weighted Radon formula from the inverse Fourier transform in the new system. Furthermore, we present the motion equation of the frequency plane and the conditions for sharp points of the instantaneous rotation axis. Our analysis on the motion of the frequency plane is related to the Frenet-Serret theorem in the differential geometry.

Wei, Yuchuan; Yu, Hengyong; Wang, Ge

2011-01-01

151

National Technical Information Service (NTIS)

Pyramidal inversion is discussed from the point of view of recent theoretical and experimental investigations in an attempt to provide a unified description of this process. Quantum mechanical studies of pyramidal molecules indicate that the origin of the...

A. Rauk L. C. Allen K. Mislow

1970-01-01

152

National Technical Information Service (NTIS)

The long term goals of this research are to develop practical and efficient algorithms for application to the nonlinear inversion problems encountered in ocean acoustics. Such algorithms would be used for estimating or accounting for the effects of the en...

R. I. Odom

2010-01-01

153

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

154

National Technical Information Service (NTIS)

This paper treats the nonlinear, two-point boundary-value problem formulated by Troesch and studied by Roberts and Shipman. Computationally speaking, this is a difficult problem, owing to the fact that the Jacobian matrix is characterized by large positiv...

A. Miele A. K. Aggarwal J. L. Tietze

1973-01-01

155

National Technical Information Service (NTIS)

The report containes ten place tables of the Jacobian elliptic functions am(u,k), sn(u,k), cn(u,k), dn(u,k) where u = mk/n, for K squared = 0(.01).99, m = 0(1)(n-1), n = 11(1)20. This tabulation was suggested by Dr. Irving L. Weiner of Multimetrics as an ...

H. E. Fettis J. C. Caslin

1972-01-01

156

A systematic and effective supervised learning mechanism based on Jacobian rank deficiency.

Most neural network applications rely on the fundamental approximation property of feedforward networks. Supervised learning is a means of implementing this approximate mapping. In a realistic problem setting, a mechanism is needed to devise this learning process based on available data, which encompasses choosing an appropriate set of parameters in order to avoid overfitting, using an efficient learning algorithm measured by computation and memory complexities, ensuring the accuracy of the training procedures as measured by the training error, and testing and cross-validation for generalization. We develop a comprehensive supervised learning algorithm to address these issues. The algorithm combines training and pruning into one procedure by utilizing a common observation of Jacobian rank deficiency in feedforward networks. The algorithm not only reduces the training time and overall complexity but also achieves training accuracy and generalization capabilities comparable to more standard approaches. Extensive simulation results are provided to demonstrate the effectiveness of the algorithm. PMID:9573418

Zhou, G; Si, J

1998-05-15

157

NASA Astrophysics Data System (ADS)

Single-fluid resistive magnetohydrodynamics (MHD) is a fluid description of fusion plasmas which is often used to investigate macroscopic instabilities in tokamaks. In MHD modeling of tokamaks, it is often desirable to compute MHD phenomena to resistive time scales or a combination of resistive-Alfvén time scales, which can render explicit time stepping schemes computationally expensive. We present recent advancements in the development of preconditioners for fully nonlinearly implicit simulations of single-fluid resistive tokamak MHD. Our work focuses on simulations using a structured mesh mapped into a toroidal geometry with a shaped poloidal cross-section, and a finite-volume spatial discretization of the partial differential equation model. We discretize the temporal dimension using a fully implicit ? or the backwards differentiation formula method, and solve the resulting nonlinear algebraic system using a standard inexact Newton-Krylov approach, provided by the sundials library. The focus of this paper is on the construction and performance of various preconditioning approaches for accelerating the convergence of the iterative solver algorithms. Effective preconditioners require information about the Jacobian entries; however, analytical formulae for these Jacobian entries may be prohibitive to derive/implement without error. We therefore compute these entries using automatic differentiation with OpenAD. We then investigate a variety of preconditioning formulations inspired by standard solution approaches in modern MHD codes, in order to investigate their utility in a preconditioning context. We first describe the code modifications necessary for the use of the OpenAD tool and sundials solver library. We conclude with numerical results for each of our preconditioning approaches in the context of pellet-injection fueling of tokamak plasmas. Of these, our optimal approach results in a speedup of a factor of 3 compared with non-preconditioned implicit tests, with that performance gap rapidly widening with increasing mesh refinement.

Reynolds, Daniel R.; Samtaney, Ravi; Tiedeman, Hilari C.

2012-01-01

158

Kinematics of Strong Discontinuities

NASA Technical Reports Server (NTRS)

Synthetic Aperture Radar (SAR) provides a detailed view of the Arctic ice cover. When processed with the RADARSAT Geophysical Processor System (RGPS), it provides estimates of sea ice motion and deformation over large regions of the Arctic for extended periods of time. The deformation is dominated by the appearance of linear kinematic features that have been associated with the presence of leads. The RGPS deformation products are based on the assumption that the displacement and velocity are smooth functions of the spatial coordinates. However, if the dominant deformation of multiyear ice results from the opening, closing and shearing of leads, then the displacement and velocity can be discontinuous. This presentation discusses the kinematics associated with strong discontinuities that describe possible jumps in displacement or velocity. Ice motion from SAR data are analyzed using this framework. It is assumed that RGPS cells deform due to the presence of a lead. The lead orientation is calculated to optimally account for the observed deformation. It is shown that almost all observed deformation can be represented by lead opening and shearing. The procedure used to reprocess motion data to account for leads will be described and applied to regions of the Beaufort Sea. The procedure not only provides a new view of ice deformation, it can be used to obtain information about the presence of leads for initialization and/or validation of numerical simulations.

Peterson, K.; Nguyen, G.; Sulsky, D.

2006-01-01

159

NASA Astrophysics Data System (ADS)

The fine-scale structure and the kinematics of relativistic active galactic nuclei (AGN) jets have been studied by very-long-baseline interferometry at very high resolutions since 1998 at 2 cm wavelength for a sample of over a hundred radio sources (VLBA 2cm Survey and MOJAVE programs). Since 2007, this is being complemented by the TANAMI project, based on southern observations with the Australian LBA at 3.6 cm and 1.1cm wavelengths. From our observation campaign, we find that most of the radio jets show linear morphologies at parsec-scales, but some of show curvature and non-radial motions. Features are observed to move at highly relativistic speeds, with Lorentz factors extending above values of 30. We also provide a brief description of the relationship of our radio findings with the AGN observations by the new Fermi Gamma-ray Space Telescope.

Ros, Eduardo

2008-10-01

160

A dual neural network is presented for the real-time joint torque optimization of kinematically redundant manipulators, which cor- responds to global kinetic energy minimization of robot mechanisms. Com- pared to other computational strategies on inverse kinematics, the dual net- work is developed at the acceleration level to resolve redundancy of lim- ited-joint-range manipulators. The dual network has a simple architecture

Yunong Zhang; Jun Wang

2002-01-01

161

The present paper describes an improved version of the elliptic averaging method that provides a highly accurate periodic solution of a non-linear system based on the single-degree-of-freedom Duffing oscillator with a snap-through spring. In the proposed method, the sum of the Jacobian elliptic delta and zeta functions is used as the generating solution of the averaging method. The proposed method

T. Okabe; T. Kondou; J. Ohnishi

2010-01-01

162

This article presents the first extended set of results from EliAD, a source-transformation implementation of the vertex-elimination Automatic Differentiation approach to calculating the Jacobians of functions defined by Fortran code (Griewank and Reese, Automatic Differentiation of Algorithms: Theory, Implementation, and Application, 1991, pp. 126--135). We introduce the necessary theory in terms of well known algorithms of numerical linear algebra applied

Shaun A. Forth; Mohamed Tadjouddine; John D. Pryce; John K. Reid

2004-01-01

163

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

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

2011-01-01

164

An implicit energy-conservative 2D Fokker-Planck algorithm -- 2. Jacobian-free Newton-Krylov solver

Energy-conservative implicit integration schemes for the Fokker-Planck transport equation in multidimensional geometries require inverting a dense, non-symmetric matrix (Jacobian), which is very expensive to store and solve using standard solvers. However, these limitations can be overcome with Newton-Krylov iterative techniques, since they can be implemented Jacobian-free (the Jacobian matrix from Newton's algorithm is never formed nor stored to proceed with the iteration), and their convergence can be accelerated by preconditioning the original problem. In this document, the efficient numerical implementation of an implicit energy-conservative scheme for multidimensional Fokker-Planck problems using multigrid-preconditioned Krylov methods is discussed. Results show that multigrid preconditioning is very effective in speeding convergence and decreasing CPU requirements, particularly in fine meshes. The solver is demonstrated on grids up to 128 x 128 points in a 2D cylindrical velocity space ({upsilon}{sub r}, {upsilon}{sub p}) with implicit time steps of the order of the collisional time scale of the problem, {tau}. The method preserves particles exactly, and energy conservation is improved over alternative approaches, particularly in coarse meshes. Typical errors in the total energy over a time period of 10{tau} remain below a percent.

Chacon, L.; Barnes, D.C.; Knoll, D.A.; Miley, G.H.

2000-01-20

165

Implicit Plasma Kinetic Simulation Using The Jacobian-Free Newton-Krylov Method

NASA Astrophysics Data System (ADS)

The use of fully implicit time integration methods in kinetic simulation is still area of algorithmic research. A brute-force approach to simultaneously including the field equations and the particle distribution function would result in an intractable linear algebra problem. A number of algorithms have been put forward which rely on an extrapolation in time. They can be thought of as linearly implicit methods or one-step Newton methods. However, issues related to time accuracy of these methods still remain. We are pursuing a route to implicit plasma kinetic simulation which eliminates extrapolation, eliminates phase-space from the linear algebra problem, and converges the entire nonlinear system within a time step. We accomplish all this using the Jacobian-Free Newton-Krylov algorithm. The original research along these lines considered particle methods to advance the distribution function [1]. In the current research we are advancing the Vlasov equations on a grid. Results will be presented which highlight algorithmic details for single species electrostatic problems and coupled ion-electron electrostatic problems. [4pt] [1] H. J. Kim, L. Chac'on, G. Lapenta, ``Fully implicit particle in cell algorithm,'' 47th Annual Meeting of the Division of Plasma Physics, Oct. 24-28, 2005, Denver, CO

Taitano, William; Knoll, Dana; Chacon, Luis

2009-11-01

166

A Jacobian-free Newton-Krylov algorithm for compressible turbulent fluid flows

NASA Astrophysics Data System (ADS)

Despite becoming increasingly popular in many branches of computational physics, Jacobian-free Newton-Krylov (JFNK) methods have not become the approach of choice in the solution of the compressible Navier-Stokes equations for turbulent aerodynamic flows. To a degree, this is related to some subtle aspects of JFNK methods that are not well understood, and, if poorly handled, can lead to inefficient and unreliable performance. These are described here, along with strategies for addressing them, leading to an efficient JFNK algorithm for turbulent aerodynamic flows applicable to multi-block structured grids and a one-equation turbulence model. Development of globalization strategies for field-equation turbulence models represents one of the key contributions of the paper. Numerous examples of subsonic and transonic flows over single and multi-element airfoils are presented in order to demonstrate the efficiency and reliability of the algorithm. In addition, a number of guidelines are presented to aid in diagnosing problems with JFNK algorithms.

Chisholm, Todd T.; Zingg, David W.

2009-05-01

167

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

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

Hansen, Glen, E-mail: Glen.Hansen@inl.gov [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415-3840 (United States)

2011-07-20

168

A Jacobian-Free Newton Krylov Method for Mortar-Discretized Thermomechanical Contact Problems

Multibody contact problems are common within the field of multiphysics simulation. Applications involving thermomechanical contact scenarios are also quite prevalent. Such problems can be challenging to solve due to the likelihood of thermal expansion affecting contact geometry which, in turn, can change the thermal behavior of the components being analyzed. This paper explores a simple model of a light water reactor nuclear reactor fuel rod, which consists of cylindrical pellets of uranium dioxide (UO2) fuel sealed within a Zircalloy cladding tube. The tube is initially filled with helium gas, which fills the gap between the pellets and cladding tube. The accurate modeling of heat transfer across the gap between fuel pellets and the protective cladding is essential to understanding fuel performance, including cladding stress and behavior under irradiated conditions, which are factors that affect the lifetime of the fuel. The thermomechanical contact approach developed here is based on the mortar finite element method, where Lagrange multipliers are used to enforce weak continuity constraints at participating interfaces. In this formulation, the heat equation couples to linear mechanics through a thermal expansion term. Lagrange multipliers are used to formulate the continuity constraints for both heat flux and interface traction at contact interfaces. The resulting system of nonlinear algebraic equations are cast in residual form for solution of the transient problem. A Jacobian-free Newton Krylov method is used to provide for fully-coupled solution of the coupled thermal contact and heat equations.

Glen Hansen

2011-07-01

169

Improving 3D active appearance model segmentation of the left ventricle with Jacobian tuning

NASA Astrophysics Data System (ADS)

Automated image processing techniques may prove invaluable in the examination of real-time three-dimensional echocardiograms, by providing quantitative and objective measurements of functional parameters such as left ventricular (LV) volume and ejection fraction. In this study, we investigate the use of active appearance models (AAMs) for automatic detection of left ventricular endocardial contours. AAMs are especially useful in segmenting ultrasound images, due to their ability to model the typical LV appearance. However, since only a limited number of images is available for training, the model may be incapable of capturing the large variability in ultrasound image appearance. This may cause standard AAM matching procedures to fail if the model and image are significantly different. Recently, a Jacobian-tuning method for AAM matching was proposed, which allowed the model's training matrix to adapt to the new, unseen image. This may potentially result in a more robust matching. To compare both matching methods, AAMs were built with end-diastolic images from 54 patients. Larger capture ranges and higher accuracy were obtained when the new method was used. In conclusion, this method has great potential for segmentation in echocardiograms and will improve the assessment of LV functional parameters.

Leung, K. Y. E.; van Stralen, M.; Voormolen, M. M.; de Jong, N.; van der Steen, A. F. W.; Reiber, J. H. C.; Bosch, J. G.

2008-04-01

170

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

171

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

NASA Astrophysics Data System (ADS)

The goal of this study is to investigate the driving mechanisms of CMEs and to infer the magnetic field properties at the onset of the instability. We use EIT 195 Å images and LASCO white-light coronagraph data of a CME event that occurred on 17 December 2006. It was a long-duration event, and was associated with an occulted C2.1 class flare. To determine the driving mechanism, we quantitatively and qualitatively compared the observationally obtained kinematic evolution with that predicted by three CME models: the breakout model (BO, see Antiochos et al. 1999; Lynch et al. 2008; DeVore and Antiochos 2008), the catastrophe model (CM, see Priest and Forbes 2000), and the toroidal instability model (TI, see Chen 1989; Kliem and Török 2006). Our results indicate that this CME is best represented by the CM model. We infer that, at the onset of the instability, the Alfvén speed is approximately 120 km s-1 and the height of the flux rope is roughly 100-200Mm. These parameter values are related to the magnetic environment and the loop geometry and can be used to infer the magnetic condition at the onset of the eruption.We intend to submit the full analysis to A&A.

Lin, C.-H.; Gallagher, P. T.

173

NASA Astrophysics Data System (ADS)

The development of two new units for the Powerful Ideas in Physical Science (PIPS) Project of the American Association of Physics Teachers, funded by the National Science Foundation has motivated another look at the learning and teaching of kinematics and force. These and some of the other units of the PIPS Project are unique in that they advocate and model a particular student understanding driven approach to instruction as opposed to the more common content driven approach. Several novel ways to view the results of using these new motion and force materials are introduced and made possible by a diagnostic capable of indicating the degree of presence of multiple views (the Force and Motion Conceptual Evaluation by Thornton and Sokoloff). The performance of individuals on pre and post diagnostic measures ranges widely from almost no change to more than 6 standard deviations. Factors are identified which appear to differentiate the student performances. The identification of these factors motivated additional rounds of modifications to the materials, departing even further from a content driven orientation toward an even more student understanding driven approach. The resulting instruction appears to induce routinely even under adverse teaching and learning conditions 2.5 standard deviations change in the class average on the pre to the post instruction diagnostic scores.

Dykstra, Dewey

2002-05-01

174

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.

175

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. Previously announced in STAR as N82-32733

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

1983-01-01

176

Dynamic Inversion of Intraslab Intermediate Depth Earthquakes

NASA Astrophysics Data System (ADS)

We perform kinematic and dynamic inversions of the 24 July 2008 (Mw=6.8) Iwate northern Japan and 16 December 2007 (Mw 6.8) Michilla, Chile earthquakes using near field strong motion digital data. The data were filtered between 0.02 - 1 Hz. The rupture process is simulated with elliptical patches because we are looking for the average properties of the seismic rupture. The direct dynamic simulation problem was solved by a combination of finite difference modeling on a 32 km3 grid with 200 m spacing, and propagation from source to recorders using the AXITRA spectral program. For both earthquakes we used layered models of the structure. The Neighborhood algorithm and Monte Carlo methods are used to obtain the best fitting solutions and to explore the solution space. The optimum solutions are found comparing observed and synthetic records using an L2 norm. Both kinematic and dynamic inversions fit the observed data with misfits lower than 0.3. For both earthquakes, kinematic inversion shows strong trade-off between rupture velocity and maximum slip although the seismic moment remains invariant. Rupture velocities vary between sub-shear speeds to almost Rayleigh wave speeds. In the dynamic inversions 10 seismic source parameters were inverted for the Michilla earthquake and 8 parameters for the Iwate event, among them stress, friction and geometrical parameters. For the Iwate event the properties of the initial asperity at the source were not inverted because they could not be resolved by the data. In the dynamic inversion we observed a strong trade off among the friction law parameters. The best dynamic models form a family of that shares similar values of seismic moment and kappa (the ratio of released strain energy to energy release rate for friction). Kinematic and dynamic inversions in the 0.02 - 1 Hz frequency range form a set of non-unique solutions controlled by specific combinations of seismic source parameters. We discuss the origin of the non-uniqueness of the inverse problem.

Madariaga, R. I.; Ruiz, S.

2011-12-01

177

Dynamically Consistent Source Time Functions to Invert Kinematic Rupture Histories

NASA Astrophysics Data System (ADS)

In the present study we aim to understand the importance of adopting source time functions (STF) compatible with earthquake dynamics to image the kinematic rupture history on a finite fault. We consider different slip velocity STFs: a boxcar, a modified cosine function and the regularized Yoffe function (Tinti et al., 2005). The latter is consistent with dynamic 'pulse-like' propagation of earthquake ruptures and makes feasible the dynamic interpretation of kinematic slip models. First, considering an array of stations distributed around the source, we compute synthetic waveforms in the frequency band 0-2 Hz commonly used in kinematic inversion. We find that the computed ground motions depend on the choice of the STF, especially at stations located near the source (within about 10 km from the fault). This suggests that the STF may have an important role when used to retrieve kinematic source models by means of waveform inversion. To this purpose we use a two-stages global search algorithm to invert strong motions to recover the rupture history of the earthquake on a finite fault (Piatanesi et al., 2006). This technique performs a statistical analysis of the model ensemble and computes a weighted mean model and its standard deviation, allowing extraction of the most stable features of the earthquake rupture that are consistent with the data and giving an estimate of the variability of each model parameter. We present several synthetic tests and an application to the 2000 western Tottori, Japan, earthquake (M_w 6.6). We find that the choice of the STF affects the inverted rupture model, especially the peak slip velocity and rise time, which are important when kinematic rupture models are used to infer dynamic parameters, such as the slip weakening distance and the dynamic stress drop. We use the inverted rupture histories as boundary conditions in pseudo-dynamic rupture modeling to compute the traction evolutions on the fault plane; we find that relevant dynamic parameters of the rupture process definitely depend on the STF used in the inverse procedure to retrieve the kinematic models.

Cirella, A.; Piatanesi, A.; Tinti, E.; Cocco, M.

2006-12-01

178

An optimal linear solver for the Jacobian system of the extreme type-II Ginzburg-Landau problem

NASA Astrophysics Data System (ADS)

This paper considers the extreme type-II Ginzburg-Landau equations, a nonlinear PDE model for describing the states of a wide range of superconductors. Based on properties of the Jacobian operator and an AMG strategy, a preconditioned Newton-Krylov method is constructed. After a finite-volume-type discretization, numerical experiments are done for representative two- and three-dimensional domains. Strong numerical evidence is provided that the number of Krylov iterations is independent of the dimension n of the solution space, yielding an overall solver complexity of O(n).

Schlömer, N.; Vanroose, W.

2013-02-01

179

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

180

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

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

181

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

NASA Technical Reports Server (NTRS)

Closed-form direct and inverse kinematics of a new three degree-of-freedom (DOF) parallel manipulator with inextensible limbs and base-mounted actuators are presented. The manipulator has higher resolution and precision than the existing three DOF mechanisms with extensible limbs. Since all of the manipulator actuators are base-mounted; higher payload capacity, smaller actuator sizes, and lower power dissipation can be obtained. The manipulator is suitable for alignment applications where only tip, tilt, and piston motions are significant. The direct kinematics of the manipulator is reduced to solving an eighth-degree polynomial in the square of tangent of half-angle between one of the limbs and the base plane. Hence, there are at most sixteen assembly configurations for the manipulator. In addition, it is shown that the sixteen solutions are eight pairs of reflected configurations with respect to the base plane. Numerical examples for the direct and inverse kinematics of the manipulator are also presented.

Tahmasebi, Farhad

2005-01-01

182

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

183

Clifford Fibrations and Possible Kinematics

NASA Astrophysics Data System (ADS)

Following Herranz and Santander [Herranz F.J., Santander M., Mem. Real Acad. Cienc. Exact. Fis. Natur. Madrid 32 (1998), 59-84, physics/9702030] we will construct homogeneous spaces based on possible kinematical algebras and groups [Bacry H., Levy-Leblond J.-M., J. Math. Phys. 9 (1967), 1605-1614] and their contractions for 2-dimensional spacetimes. Our construction is different in that it is based on a generalized Clifford fibration: Following Penrose [Penrose R., Alfred A. Knopf, Inc., New York, 2005] we will call our fibration a Clifford fibration and not a Hopf fibration, as our fibration is a geometrical construction. The simple algebraic properties of the fibration describe the geometrical properties of the kinematical algebras and groups as well as the spacetimes that are derived from them. We develop an algebraic framework that handles all possible kinematic algebras save one, the static algebra.

McRae, Alan S.

2009-07-01

184

The use of the Jacobian-free Newton-Krylov (JFNK) method within the context of nonlinear diffusion acceleration (NDA) of source iteration is explored. The JFNK method is a synergistic combination of Newton's method as the nonlinear solver and Krylov methods as the linear solver. JFNK methods do not form or store the Jacobian matrix, and Newton's method is executed via probing the nonlinear discrete function to approximate the required matrix-vector products. Current application of NDA relies upon a fixed-point, or Picard, iteration to resolve the nonlinearity. We show that the JFNK method can be used to replace this Picard iteration with a Newton iteration. The Picard linearization is retained as a preconditioner. We show that the resulting JFNK-NDA capability provides benefit in some regimes. Furthermore, we study the effects of a two-grid approach, and the required intergrid transfers when the higher-order transport method is solved on a fine mesh compared to the low-order acceleration problem.

Dana A. Knoll; H. Park; Kord Smith

2011-02-01

185

NASA Astrophysics Data System (ADS)

In the existing literatures, modal analysis for steady-state voltage stability is based on the reduced Jacobian matrix, i.e. active power equations are eliminated, and reactive power equations of the constant power/voltage buses (PV buses) are ignored in the polar coordinate expression, which is actually designed for voltage controllability, but questionable for voltage stability.In this article, power outputs of the rotating machines are newly decomposed to the steady-state and dynamic components, with the latter proportional to derivative of the rotor flux. Therefore, neither the active nor the reactive power equations of the rotating machines may be eliminated or ignored in the Jacobian matrix. Only the static buses with constant load impedance should be eliminated. Numerical results show that elimination of active power equations or ignorance of reactive power equations of the rotating machines will yield optimistic stability margins, while including power equations of static load buses yields pessimistic stability margin. It is also find that more static load component yields larger stability margin.

Li, Shenghu

2013-06-01

186

Kinematics of the western Mediterranean

I I SUMMARY: The kinematic understanding of the relationship between relative plate motion and the structure of orogenic belts depends upon a knowledge of relative plate motion across the plate boundary system, the relative motion of small blocks and flakes within the system, an evaluation of orogenic body forces, and an understanding of the thermomechanical evolution of the upper part

J. F. Dewey; M. L. Helman; S. D. Knott; E. Turco; D. H. W. Hutton

1989-01-01

187

Kinematic Parameters of Signed Verbs

ERIC Educational Resources Information Center

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

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

2013-01-01

188

Trajectory optimization for kinematically redundant arms

NASA Technical Reports Server (NTRS)

A review of local optimization methods for resolving joint configurations in underconstrained manipulation tasks is conducted. A new approach is developed for observing joint limits and avoiding obstacles during the trajectory planning. The methodology is used in a four-link arm example to avoid a workspace singularity and is compared with results using the extended Moore-Penrose technique. An alternative measure of arm 'manipulability' based directly on the rank of the Jacobian is also introduced.

Carignan, Craig R.

1991-01-01

189

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

190

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

191

Testing Iberian kinematics at Jurassic-Cretaceous times

NASA Astrophysics Data System (ADS)

reconstructions of Iberia at the Mesozoic are still a matter of debate. The incompatibility between kinematic models and paleomagnetic data older than 120 Ma is a major problem for which no cause has yet been determined. Here we use a new method to investigate the origin of this misfit. We solve the inverse problem of finding the Euler poles that fit paleomagnetic poles with the Global Apparent Polar Wander Path (GAPWP) and then test their implications on Iberian reconstructions. We show that Iberian poles from the Early Cretaceous (mean poles for 123 and 130 Ma) are incompatible with the GAPWP, bringing into question their validity. Contrarily, Late Jurassic data (mean pole at 151 Ma) are compatible with the GAPWP and, thus, can be considered reliable. Based on these results, we propose a new magnetic reconstruction of Iberia and surrounding plates at ~150 Ma (M22 anomaly). This work provides new constraints for the kinematic evolution of Iberia during Jurassic-Cretaceous. However, the development of a detailed and consensual model for the kinematic evolution of Iberia is dependent on the acquisition of new, high-quality paleomagnetic data and a reevaluation of seafloor magnetic anomalies.

Neres, M.; Miranda, J. M.; Font, E.

2013-09-01

192

Observation of the Inverse Doppler Effect

NASA Astrophysics Data System (ADS)

We report experimental observation of an inverse Doppler shift, in which the frequency of a wave is increased on reflection from a receding boundary. This counterintuitive effect has been produced by reflecting a wave from a moving discontinuity in an electrical transmission line. Doppler shifts produced by this system can be varied in a reproducible manner by electronic control of the transmission line and are typically five orders of magnitude greater than those produced by solid objects with kinematic velocities. Potential applications include the development of tunable and multifrequency radiation sources.

Seddon, N.; Bearpark, T.

2003-11-01

193

Kinematic Fitting of Detached Vertices

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

194

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

195

Science of NHL Hockey: Kinematics

NSDL National Science Digital Library

NHL skaters can reach speeds in excess of 20 miles (32km) per hour, and during some short bursts approach 30 miles (48 km) per hour. Kinematics, the branch of classical mechanics, helps describe a player's movement across the ice by defining his position, velocity and acceleration. "Science of NHL Hockey" is a 10-part video series produced in partnership with the National Science Foundation and the National Hockey League.

Learn, Nbc

2010-10-07

196

Teaching Kinematics With Angry Birds

NSDL National Science Digital Library

The paper "Teaching Physics Wiht Angry Birds" explores classroomâs strategies for teaching kinematics at middle and high school levels, using Rovio's game Angry Birds, and the video analyser software Tracker. The paper shows how to take advantage of this fun video game, by recording appropriate motions of birds that students can explore for manipulating data, characterizing the red birdâs motion and fit results to physical models.

Rodrigues, Marcelo; Carvalho, Paulo

2013-09-24

197

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

198

Physics Suite Thinking Problems: Kinematics

NSDL National Science Digital Library

This is a collection of introductory physics problems on topics in kinematics. The questions are designed for active learning classrooms and are built around research on student acquisition of knowledge. The problems vary in format and include context-based reasoning, multiple choice, estimation, and essay questions. The topics include velocity and acceleration, graphs, and different representations of motion. This item is part of a larger collection of problems, in-class questions, and interactive resources developed by the University of Maryland Physics Education Research Group.

Redish, Edward F.

2008-07-18

199

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 produce 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

200

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

201

Note: a Piezo Tip/Tilt Platform: structure, kinematics, and experiments.

A Piezo Tip/Tilt Platform (PT(2)P) is presented with its structure, kinematics, and preliminary experiments. Two essential models of the presented PT(2)P, an equivalent hinge of the flexure hinge and a simplified model of the transmission mechanism, are discussed with the analysis on the structure of the PT(2)P. Based on these models, the inverse kinematics of the PT(2)P is derived. Two experiments are conducted on a prototype of the PT(2)P. The kinematic model is verified with experimental results, which also indicate that the resolution and the repeatability of the PT(2)P is, respectively, better than 0.50 ?rad and 0.25 ?rad. PMID:24784680

Du, Z; Su, Y; Yang, W; Dong, W

2014-04-01

202

Dynamic inversion of the 2000 Tottori earthquake based on elliptical subfault approximations

NASA Astrophysics Data System (ADS)

We propose a simplified nonlinear method for the kinematic and dynamic inversion of near-field strong motion data at low frequencies. Using a few elliptical patches we reduce the number of independent parameters of the inverse problem. We apply this method to the dynamic inversion of the Western Tottori (Japan) earthquake (Mw 6.6-6.8) of 6 October 2000. Using unfiltered records we relocated the hypocenter close to 14 km in depth. Fifteen records obtained by the KiK-net and K-NET accelerometer networks were then filtered to the 0.1-0.5 Hz frequency range and integrated to displacement. We compare observed and synthetic records using the ?2 norm. A nonlinear kinematic inversion for the elliptical subfaults is first computed using the neighborhood algorithm (NA). Inversion converges to a slip distribution modeled by just two elliptical patches. We then propose a dynamic inversion method based on the same simple geometrical ideas. Dynamic rupture propagation is computed by finite differences on a coarse numerical grid. Rupture propagation is controlled by a classical slip weakening friction law. Inversion is implemented with the NA for a barrier model. In this model prestress is uniform and rupture propagation is arrested by a simple distribution of barriers. Inversion converges to a model with two elliptical barriers. Synthetics computed for the dynamic inversion fit the observed data, reducing the variance by nearly 60%. By making different assumptions about the rupture process we illustrate the nonuniqueness of the solution to dynamic inversion.

di Carli, Sara; FrançOis-Holden, Caroline; Peyrat, Sophie; Madariaga, Raul

2010-12-01

203

Kinematically Decoupled Cores in Dwarf (Elliptical) Galaxies

NASA Astrophysics Data System (ADS)

An overview is given of what we know about the frequency of kinematically decoupled cores in dwarf elliptical galaxies. New observations show that kinematically decoupled cores happen just as often in dwarf elliptical as in ordinary early-type galaxies. This has important consequences for the formation of kinematically decoupled cores. Our currently most popular theory for kinematically decoupled cores in dwarf ellipticals is that they were formed in a poor group environment or in isolation, and subsequent fell into the cluster environment where star formation was quenched.

Toloba, E.; Peletier, R. F.; Guhathakurta, P.; van de Ven, G.; Boissier, S.; Boselli, A.; Brok, M. d.; Falcón-Barroso, J.; Hensler, G.; Janz, J.; Laurikainen, E.; Lisker, T.; Paudel, S.; Ry?, A.; Salo, H.

2014-05-01

204

We revisit the method of kinematical endpoints for particle mass determination, applied to the popular SUSY decay chain tilde q --> tilde chi02 --> tilde l --> tilde chi01. We analyze the uniqueness of the solutions for the mass spectrum in terms of the measured endpoints in the observable invariant mass distributions. We provide simple analytical inversion formulas for the

Michael Burns; Konstantin T. Matchev

2009-01-01

205

Weak Lensing with Galaxy Kinematics

NASA Astrophysics Data System (ADS)

Weak lensing is weak because the shear signal is much smaller than the noise set by the broad distribution of intrinsic galaxy shapes. We describe a technique that can reduce shape noise by an order of magnitude using spatially-resolved spectroscopy to derive kinematic maps of source galaxies. Shear oriented along the principle axes of a rotating disk induces an offset from the Tully-Fisher relation after inclination corrections, while shear applied at an angle to the disk skews the kinematic axes relative to the photometric axes. Existing multi-object optical spectrographs and IFUs have the spatial and spectral resolution to measure this effect at high signal-to-noise. We discuss science applications ranging from high resolution cluster mass mapping to cosmic shear, including the statistical and systematic uncertainties which can be competitive with and complementary to traditional shear surveys. Notably, the need for photometric redshifts is eliminated, while biases due to shear calibration and intrinsic alignments can be significantly reduced.

George, Matthew R.; Huff, E. M.; Schlegel, D. J.

2014-01-01

206

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

207

Inverse dynamics control of floating base systems using orthogonal decomposition

Model-based control methods can be used to enable fast, dexterous, and compliant motion of robots without sacrificing control accuracy. However, implementing such techniques on floating base robots, e.g., humanoids and legged systems, is non-trivial due to under-actuation, dynamically changing constraints from the environment, and potentially closed loop kinematics. In this paper, we show how to compute the analytically correct inverse

Michael Mistry; Jonas Buchli; Stefan Schaal

2010-01-01

208

Robust magnetotelluric inversion

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

209

In present-day forward time stepping ocean-climate models, capturing both the wind-driven and thermohaline components, a substantial amount of CPU time is needed in a so-called spin-up simulation to determine an equilibrium solution. In this paper, we present methodology based on Jacobian-Free Newton–Krylov methods to reduce the computational time for such a spin-up problem. We apply the method to an idealized

Erik Bernsen; Henk A. Dijkstra; Jonas Thies; Fred W. Wubs

2010-01-01

210

Optimal Trajectory Planning for Wheeled Mobile Robots Based on Kinematics Singularity

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

211

Inverse Common-Reflection-Surface

NASA Astrophysics Data System (ADS)

The Common-Reflection-Surface (CRS) stack method is a powerful tool to produce high-quality stacked images of multicoverage seismic data. As a result of the CRS stack, not only a stacked section, but also a number of attributes defined at each point of that section, are produced. In this way, one can think of the CRS stack method as a transformation from data space to attribute space. Being a purely kinematic method, the CRS stack lacks amplitude information that can be useful for many purposes. Here we propose to fill this gap by means of a combined use of a zero-offset section (that could be a short-offset or amplitude-corrected stacked section) and common midpoint gather. We present an algorithm for an inverse CRS transformation, namely one that (approximately) transforms the CRS attributes back to data space. First synthetic tests provide satisfying results for the two simple cases of single dipping-plane and single circular reflectors with a homogeneous overburden, and provide estimates of the range of applicability, in both midpoint and offset directions. We further present an application for interpolating missing traces in a near-surface, high-resolution seismic experiment, conducted in the alluvial plain of the river Gave de Pau, near Assat, southern France, showing its ability to build coherent signals, where recording was not available. A somewhat unexpected good feature of the algorithm, is that it seems capable to reconstruct signals even in muted parts of the section.

Perroud, H.; Tygel, M.; Freitas, L.

2010-12-01

212

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

213

The Kinematic Cascade as a Hydrologic Model.

National Technical Information Service (NTIS)

A kinematic cascade is defined as a sequence of discrete overland flow planes or channel segments in which the kinematic wave equations are used to describe the unsteady flow. Each plane or channel is characterized by a length, width, and a roughness-slop...

D. F. Kibler D. A. Woolhiser

1970-01-01

214

Philippine fault: A key for Philippine kinematics

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

E. Barrier; P. Huchon; M. Aurelio

1991-01-01

215

Automatic target recognition using kinematic priors

Traditional automatic target recognition (ATR) systems discriminate based upon target size, target shape, or both. In this paper, an ATR algorithm is proposed that exploits aircraft-class specific kinematics to assess the tracked target's likelihood. Prior information on kinematics includes the physical parameters of the aircraft, allowable input forces to a pilot, and pilot behavior in the aircraft. It is shown

Nicholas J. Cutaia; J. A. O'Sullivan

1994-01-01

216

Origin of kinematic subsystems in elliptical galaxies

NASA Technical Reports Server (NTRS)

The formation of a counterrotating central gas disk in a merger of two gas-rich disk galaxies of equal mass is demonstrated. Such a structure may well account for the unusual gas kinematics found in the merger remnant NGC7252. Continued star formation in such gaseous disks may produce central components with decoupled kinematics resembling the cores of some elliptical galaxies.

Hernquist, Lars; Barnes, Joshua E.

1991-01-01

217

Hamstring Muscle Kinematics during Treadmill Sprinting

THELEN, D. G., E. S. CHUMANOV, D. M. HOERTH, T. M. BEST, S. C. SWANSON, L. LI, M. YOUNG, and B. C. HEIDERSCHEIT. Hamstring Muscle Kinematics during Treadmill Sprinting. Med. Sci. Sports Exerc., Vol. 37, No. 1, pp. 108-114, 2005. Introduction\\/Purpose: The objective of this study was to characterize hamstring muscle kinematics during sprinting, so as to provide scientific data

DARRYL G. THELEN; ELIZABETH S. CHUMANOV; DINA M. HOERTH; THOMAS M. BEST; STEPHEN C. SWANSON; LI LI; MICHAEL YOUNG; BRYAN C. HEIDERSCHEIT

2005-01-01

218

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

219

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.

MEERSCHAERT, MARK M.; STRAKA, PETER

2013-01-01

220

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

221

Inversion of high frequency surface waves with fundamental and higher modes

The phase velocity of Rayleigh-waves of a layered earth model is a function of frequency and four groups of earth parameters: compressional (P)-wave velocity, shear (S)-wave velocity, density, and thickness of layers. For the fundamental mode of Rayleigh waves, analysis of the Jacobian matrix for high frequencies (2-40 Hz) provides a measure of dispersion curve sensitivity to earth model parameters. S-wave velocities are the dominant influence of the four earth model parameters. This thesis is true for higher modes of high frequency Rayleigh waves as well. Our numerical modeling by analysis of the Jacobian matrix supports at least two quite exciting higher mode properties. First, for fundamental and higher mode Rayleigh wave data with the same wavelength, higher modes can "see" deeper than the fundamental mode. Second, higher mode data can increase the resolution of the inverted S-wave velocities. Real world examples show that the inversion process can be stabilized and resolution of the S-wave velocity model can be improved when simultaneously inverting the fundamental and higher mode data. ?? 2002 Elsevier Science B.V. All rights reserved.

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

2003-01-01

222

Relationship between gait biomechanics and inversion sprains: a prospective study of risk factors

This prospective study determined gait related risk factors for inversion sprains in 223 physical education students. Static lower leg alignment was determined, and 3D-kinematics combined with plantar pressure profiles were collected. After evaluation, the same sports physician registered all sports injuries during the next 6–18 months. During this period, 21 subjects had an inversion sprain, one of whom had a

T. Willems; E. Witvrouw; K. Delbaere; A. De Cock; D. De Clercq

2005-01-01

223

Inversion of Gamow's formula and inverse scattering

Gamow's tunneling formula is inverted and the issue of the uniqueness of the solution is compared with the solution obtained by the method of Gel'fand and Levitan. Some insight is gained into the key differences between classical and quantum inverse scattering, which account for the fact that a potential can be uniquely determined in the latter but only to within

Sohang C. Gandhi; Costas J. Efthimiou

2006-01-01

224

The Effect of End Constraints on Protein Loop Kinematics

Abstract Despite the prevalent involvement of loops in function little is known about how the constraining of end groups influences their kinematics. Using a linear inverse-kinematics approach and assuming fixed bond lengths, bond angles, and peptide bond torsions, as well as ignoring molecular interactions to assess the effect of the end-constraint only, it is shown that the constraint creates a closed surface in torsion angle space. For pentapeptides, the constraint gives rise to inaccessible regions in a Ramachandran plot. This complex and tightly curved surface produces interesting effects that may play a functional role. For example, a small change in one torsion angle can radically change the behavior of the whole loop. The constraint also produces long-range correlations, and structures exist where the correlation coefficient is 1.0 or ?1.0 between rotations about bonds separated by >30 Å. Another application allows some torsion angles to be targeted to specified values while others are constrained. When this application was used on key torsions in lactate dehydrogenase, it was found that the functional loop first folds forward and then moves sideways. For horse liver alcohol dehydrogenase, it was confirmed that the functional loop's Pro-Pro motif creates a rigid arm in an NAD-activated switch for domain closure.

Hayward, Steven; Kitao, Akio

2010-01-01

225

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

226

Three-dimensional unstructured tetrahedral and hexahedral finite element mesh optimization is studied from a theoretical perspective and by computer experiments to determine what objective functions are most effective in attaining valid, high quality meshes. The approach uses matrices and matrix norms to extend the work in Part I to build suitable 3D objective functions. Because certain matrix norm identities which hold for 2 x 2 matrices do not hold for 3 x 3 matrices. significant differences arise between surface and volume mesh optimization objective functions. It is shown, for example, that the equivalence in two-dimensions of the Smoothness and Condition Number of the Jacobian matrix objective functions does not extend to three dimensions and further. that the equivalence of the Oddy and Condition Number of the Metric Tensor objective functions in two-dimensions also fails to extend to three-dimensions. Matrix norm identities are used to systematically construct dimensionally homogeneous groups of objective functions. The concept of an ideal minimizing matrix is introduced for both hexahedral and tetrahedral elements. Non-dimensional objective functions having barriers are emphasized as the most logical choice for mesh optimization. The performance of a number of objective functions in improving mesh quality was assessed on a suite of realistic test problems, focusing particularly on all-hexahedral ''whisker-weaved'' meshes. Performance is investigated on both structured and unstructured meshes and on both hexahedral and tetrahedral meshes. Although several objective functions are competitive, the condition number objective function is particularly attractive. The objective functions are closely related to mesh quality measures. To illustrate, it is shown that the condition number metric can be viewed as a new tetrahedral element quality measure.

Knupp, P.M.

1999-03-26

227

Inverse Lighting for Photography

We introduce a technique for improving photographs using inverse lighting, a new process based on algorithms developed in computer graphics for computing the reflection of light in 3D space. From a photograph and a 3D surface model for the object pictured, inverse lighting estimates the directional distribution of the incident light. We then use this information to process the photograph

Donald P. Greenberg; Stephen R. Marschner

1997-01-01

228

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

229

ERIC Educational Resources Information Center

Voice is the carrier of speech but is also an ''auditory face'' rich in information on the speaker's identity and affective state. Three experiments explored the possibility of a ''voice inversion effect,'' by analogy to the classical ''face inversion effect,'' which could support the hypothesis of a voice-specific module. Experiment 1 consisted…

Bedard, Catherine; Belin, Pascal

2004-01-01

230

With the rapid advances in sophisticated solar modeling and the abundance of high-quality solar pulsation data, efficient and robust inversion techniques are crucial for seismic studies. We present some aspects of an efficient Fourier Optimally Localized Averaging (OLA) inversion method with an example applied to time-distance helioseismology.

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

2009-09-16

231

Multidimensional inverse scattering problems

Summary form only given, as follows. An overview of the author's results is given. The inverse problems for obstacle, geophysical and potential scattering are considered. The basic method for proving uniqueness theorems in one- and multi-dimensional inverse problems is discussed and illustrated by numerous examples. The method is based on property C for pairs of differential operators. Property C stands

Alexander G. Ramm

1999-01-01

232

s are presented for seven papers with titles including, Uniqueness of solutions to the inverse acoustic scattering problem, Far field patterns in acoustic and electromagnetic scattering, Dense sets and far field patterns in electromagnetic wave propagation, The inverse scattering problem for time harmonic acoustic waves, and The strong maximum principle for the heat equation.

D. L. Colton

1984-01-01

233

Algebra Lab: Inverse Variation

NSDL National Science Digital Library

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

2012-01-01

234

Stellar kinematics in the galactic centre

NASA Technical Reports Server (NTRS)

The observations of the stellar kinematics in the central 8 pc of the Galaxy are presented. It is shown that the spectroscopy of the 2.3 microns CO absorption feature, in late type stars, yields the stellar velocity dispersion and the average stellar radial velocity as a function of galactocentric distance. A sample spectra that illustrates the observed velocity shifrs and velocity dispersion is given. The analysis shows that the velocity dispersion of the stars is large, and that it dominates the stellar kinematics. The use of these kinematic data, to probe the mass distribution in the Galactic center, is considered.

Mcginn, M. T.; Sellgren, K.; Becklin, E. E.; Hall, D. N. B.

1989-01-01

235

Inverting Source Time Functions to determine the fault kinematic characteristics

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

236

Plasma inverse transition acceleration

It can be proved fundamentally from the reciprocity theorem with which the electromagnetism is endowed that corresponding to each spontaneous process of radiation by a charged particle there is an inverse process which defines a unique acceleration mechanism, from Cherenkov radiation to inverse Cherenkov acceleration (ICA) [1], from Smith-Purcell radiation to inverse Smith-Purcell acceleration (ISPA) [2], and from undulator radiation to inverse undulator acceleration (IUA) [3]. There is no exception. Yet, for nearly 30 years after each of the aforementioned inverse processes has been clarified for laser acceleration, inverse transition acceleration (ITA), despite speculation [4], has remained the least understood, and above all, no practical implementation of ITA has been found, until now. Unlike all its counterparts in which phase synchronism is established one way or the other such that a particle can continuously gain energy from an acceleration wave, the ITA to be discussed here, termed plasma inverse transition acceleration (PITA), operates under fundamentally different principle. As a result, the discovery of PITA has been delayed for decades, waiting for a conceptual breakthrough in accelerator physics: the principle of alternating gradient acceleration [5, 6, 7, 8, 9, 10]. In fact, PITA was invented [7, 8] as one of several realizations of the new principle.

Xie, Ming

2001-06-18

237

Nonlinear inversion of the P-wave P-wave reflection coefficient data

Surface seismic data are used to estimate lithologic parameters at an interface. The four unknown independent parameters at an interface are the ratio of the P-wave velocities and the ratio of the densities of upper and lower media, and the P-wave/S-wave velocity ratios in the upper and lower media respectively. The forward problem is solved by a reparameterized form of the full Zoeppritz equation for PP reflections. The inversion model is fitted to the data using a two part inversion scheme. The near offset (near normal incidence) data is initially inverted using a linearized Zoeppritz normal incidence equation to obtain estimates of the P-wave ratio and density ratio. The estimates of these two parameters are then used as initial guesses in a nonlinear full Zoeppritz inversion by a Levenberg Marquardt procedure. Partial derivatives of the reparameterized Zoeppritz equation for the Jacobian matrix are calculated analytically at each iteration. All parameters are successfully estimated from synthetic data. Poisson`s ratio of the upper and lower media can be calculated from inversion estimates of P-wave/S-wave velocity ratio. Lithologic parameters are estimated for several CDP gathers from a 3D survey of the Rabbit Hills Field in North Central Montana. A sensitivity analysis for the different parameters is performed.

Pate, A.J. [Univ. of Montana, Butte, MT (United States)

1996-06-01

238

Kinematics of the Lag-Luminosity Relationship.

National Technical Information Service (NTIS)

Herein the author reviews the argument that kinematics, i.e. relativistic motions of the emitting source in gamma-ray bursts (GRBs), are the cause of the lag-luminosity relationship observed in bursts with known redshifts.

J. D. Salmonson

2002-01-01

239

An inverse method for the recovery of tissue parameters from colour images.

The interpretation of colour images is presented as an inverse problem in which a mapping is sought between image colour vectors and the physiological parameters characterizing a tissue. To ensure the necessary one-to-one correspondence between the image colours and the parameters, the mapping must be unique. This can be established through testing the sign of the determinant of the Jacobian matrix, a multi-dimensional equivalent of a discrete derivative, over the space of all parameter values. Furthermore, an optimisation procedure is employed to find the set of filters for image capture which generate image vectors minimizing the mapping error. This methodology applied to interpretation of skin images shows that the standard RGB system of filters provides for a unique mapping between image values and parameters characterizing the normal skin. It is further shown that an optimal set of filters reduces the error of quantification by a factor of 2, on average. PMID:15344467

Claridge, Ela; Preece, Steve J

2003-07-01

240

National Technical Information Service (NTIS)

Some fundamental aspects of the physiocochemical charcterization of propellant prepolymers were explored for the purpose of developing and optimizing analytical procedure for molecular weight, degree of branching, and functionality distributions. Inverse ...

R. J. Laub

1990-01-01

241

Resonances and inverse scattering

NASA Astrophysics Data System (ADS)

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

Bledsoe, Matthew B.

242

Geological Inverse Theory Resources

NSDL National Science Digital Library

This website from Andrew A. Ganse of the University of Washington's Applied Physics Laboratory includes a list of resources on geophysical inverse theory. It includes introductory material, textbooks, papers, web resources, lab lecture notes and more.

Ganse, Andrew A.

2011-07-22

243

Electromagnetic Inverse Scattering Theory.

National Technical Information Service (NTIS)

An effective zero order scattering theory for perfect conductors, consistent with monostatic high range resolution radar concepts, is developed. With the aid of this theory, a basic Inverse Scattering Identity is then developed that states that the charac...

N. N. Bojarski

1968-01-01

244

The inverse p-median problem consists in changing the weights of the customers of a p-median location problem at minimum cost such that a set of p prespecified suppliers becomes the p-median. The cost is proportional to the increase or decrease of the corresponding weight. We show that the discrete version of an inverse p-median problem can be formulated as a

Rainer E. Burkard; Carmen Pleschiutschnig; Jianzhong Zhang

2004-01-01

245

Interactive inversion in geosciences

Inversion algorithms numerically evaluate the mis- match between model and data to guide the search for minima in parameter spaces. In an alternative approach, the numerical evaluation of data misfit can be replaced by subjectively judging the solution's quality. This widens the class of problems that can be treated within the framework of formal inverse theory—in particular, var- ious geophysical\\/geological\\/geodynamic

F. Boschetti; L. Moresi

2001-01-01

246

This paper firstly provides a re-appraisal of the development oftechniques for inverting deduction, secondly introduces Mode-Directed InverseEntailment (MDIE) as a generalisation and enhancement of previous approachesand thirdly describes an implementation of MDIE in the Progol system. Progol isimplemented in C and available by anonymous ftp. The re-assessment of previoustechniques in terms of inverse entailment leads to new results for learning

Stephen Muggleton

1995-01-01

247

NASA Astrophysics Data System (ADS)

We present statements and a method of solution to the inverse scattering problem of reconstructing permittivity of a dielectric inclusion in a 2D or 3D waveguide from the transmission characteristics. The approach employs a volume singular integral equation (VSIE) method. The unique solvability of VSIE is established. The inverse problem is solved by the method of iterations applied to VSIE; the convergence of the method is proved

Shestopalov, Yury; Smirnov, Yury

2012-02-01

248

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

249

NASA Astrophysics Data System (ADS)

Many partial differential equation systems in computational geophysics can be categorized as stiff wave systems. Stiff wave systems are systems which exhibit a slow dynamical time scale while possessing fast wave phenomena. The physical effects of this fast wave may be important to the system, but resolving the fast time scale may not be required. When simulating such phenomena one would like to use time steps on the order of the dynamical scale for time integration. Historically, Semi-Implicit (SI) methods have been developed to step over the stiff wave time scale in a stable fashion. However, SI methods require some linearization and time splitting, and both of these can produce additional time integration errors. In this paper, the concept of using SI methods as preconditioners to Jacobian-Free Newton-Krylov (JFNK) methods is developed. This algorithmic approach results in an implicitly balanced method (no linearization or time splitting). In this presentation, we provide an overview of SI methods in a variety of applications, and a brief background on JFNK methods. We will present details of our combined algorithmic approach. Foundational algorithmic performance results coming from representative problems in geophysical fluid dynamics and magnetohydrodynamics (MHD) will be presented. Following this introduction to the fundamental concepts we will discuss two more detailed directions. First we will present results coming from application of these ideas to 3-D MHD in a large scale parallel computing environment. We will also discuss the impact that these algorithms are having on simulation studies of fast magnetic reconnection. We will discuss the concept of barotropic-baroclinic splitting and the resulting SI algorithm for a free-surface ocean model. We will show how this algorithm can be cast as a preconditioner for a fully-implicit, JFNK based, ocean simulation code. We will also discuss issues related to accuracy and long time integration with some results from atmospheric simulations. Finally, we will briefly discuss the application of JFNK and physics-based preconditioning to other problems in computational geophysics such as sea ice modeling and ice sheet modeling.

Knoll, D. A.; Chacon, L.; Evans, K. J.

2009-12-01

250

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

251

Paritioned inversion of seismic and geodetic data for high-resolution source inversions

NASA Astrophysics Data System (ADS)

Due to the availability of earthquake data spanning a very broad range of frequencies and spatial scales (e.g. geodetic, strong-motion, teleseismic data) we now have the potential of obtaining highly detailed views of the earthquake rupture process. The sheer quantity of the data, and the heterogeneity, do pose problems for simultaneous inversion procedures both in terms of scale of the problem as well as how much influence different datasets have over the final result. A simple solution to the problem outlined above, taking advantage of the aforementioned richness in data density and variability, is to divide the inversion procedure into two steps. The first step involves inverting for the slip distribution, which would then be used as a constraint in the second step where we invert for the kinematic parameters. The advantage of this approach is that we now have a-priori knowledge of the slip model before the second inversion that can help reduce the number of free parameters significantly. Practically speaking, we can remove the grid points that have negligible slip, and we can tailor the maximum rise time for every subfault to the total amount of slip on that subfault. It would also be feasible to reduce the length of the timesteps, which gives us an improved resolution of the slip history and allows us to search for a larger range of rupture velocities. Such a method makes more optimal use of the data than a simultaneous inversion. We will present results for some large recent earthquakes to demonstrate the feasibility of this approach, and discuss the applicability of this method to more dynamically oriented inversions.

Thio, H.

2004-12-01

252

Inversion of multivariable linear systems

A new algorithm for constructing an inverse of a multivariable linear dynamical system is presented. This algorithm, which is considerably more efficient than previous methods, also incorporates a relatively simple criterion for determining if an inverse system exists. New insight into the structure of a system inverse is gained by consideration of the inverse system representations resulting from the algorithm.

L. Silverman

1969-01-01

253

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

254

Kinematic Models for Design Digital Library

NSDL National Science Digital Library

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

255

Some Results on Inverse Scattering

NASA Astrophysics Data System (ADS)

A review of some of the author's results in the area of inverse scattering is given. The following topics are discussed: (1) Property C and applications, (2) Stable inversion of fixed-energy 3D scattering data and its error estimate, (3) Inverse scattering with “incomplete” data, (4) Inverse scattering for inhomogeneous Schrödinger equation, (5) Krein's inverse scattering method, (6) Invertibility of the steps in Gel'fand-Levitan, Marchenko, and Krein inversion methods, (7) The Newton-Sabatier and Cox-Thompson procedures are not inversion methods, (8) Resonances: existence, location, perturbation theory, 9) Born inversion as an ill-posed problem, (10) Inverse obstacle scattering with fixed-frequency data, (11) Inverse scattering with data at a fixed energy and a fixed incident direction, (12) Creating materials with a desired refraction coefficient and wave-focusing properties.

Ramm, A. G.

256

Foot kinematics and loading of professional athletes in American football-specific tasks.

The purpose of this study was to describe stance foot and ankle kinematics and the associated ground reaction forces at the upper end of human performance in professional football players during commonly performed football-specific tasks. Nine participants were recruited from the spring training squad of a professional football team. In a motion analysis laboratory setting, participants performed three activities used at the NFL Scouting Combine to assess player speed and agility: the 3-cone drill, the shuttle run, and the standing high jump. The talocrural and first metatarsophalangial joint dorsiflexion, subtalar joint inversion, and the ground reaction forces were determined for the load bearing portions of each activity. We documented load-bearing foot and ankle kinematics of elite football players performing competition-simulating activities, and confirmed our hypothesis that the talocrural, subtalar, and metatarsophalangeal joint ranges of motion for the activities studied approached or exceeded reported physiological limits. PMID:22591791

Riley, Patrick O; Kent, Richard W; Dierks, Tracy A; Lievers, W Brent; Frimenko, Rebecca E; Crandall, Jeff R

2013-09-01

257

NASA Technical Reports Server (NTRS)

An efficient approach to cartesian motion and force control of a 7 degree of freedom (DOF) manipulator is presented. It is based on extending the active stiffness controller to the 7 DOF case in general and use of an efficient version of the gradient projection technique for solving the inverse kinematics problem. Cooperative control is achieved through appropriate configuration of individual manipulator controllers. In addition, other aspects of trajectory generation using standard techniques are integrated into the controller. The method is then applied to a specific manipulator of interest (Robotics Research T-710). Simulation of the kinematics, dynamics, and control are provided in the context of several scenarios: one pertaining to a noncontact pick and place operation; one relating to contour following where contact is made between the manipulator and environment; and one pertaining to cooperative control.

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

1989-01-01

258

Generalized inverse seesaw mechanisms

NASA Astrophysics Data System (ADS)

The seesaw mechanism can be generalized to a type-III variant and a quintuplet variant. We present two models that provide analogous generalizations of the inverse seesaw mechanism. The first model employs a real fermion triplet F˜(1,3,0) and requires no additional multiplets or parameters relative to the standard inverse seesaw. We argue that, from a bottom-up perspective, there appears to be no particular reason to preference the usual scenario over this variant. The second model employs a fermion quintuplet F˜(1,5,0) and requires an additional scalar S˜(1,4,1). We also show that minimal inverse seesaws with even larger fermionic representations are not expected to realize naturally small neutrino masses.

Law, Sandy S. C.; McDonald, Kristian L.

2013-06-01

259

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

260

SMACK - SMOOTHING FOR AIRCRAFT KINEMATICS

NASA Technical Reports Server (NTRS)

The computer program SMACK (SMoothing for AirCraft Kinematics) is designed to provide flightpath reconstruction of aircraft forces and motions from measurements that are noisy or incomplete. Additionally, SMACK provides a check on instrument accuracy and data consistency. The program can be used to analyze data from flight-test experiments prior to their use in performance, stability and control, or aerodynamic modeling calculations. It can also be used in the analysis of aircraft accidents, where the actual forces and motions may have to be determined from a very limited data set. Application of a state-estimation method for flightpath reconstruction is possible because aircraft forces and motions are related by well-known equations of motion. The task of postflight state estimation is known as a nonlinear, fixed-interval smoothing problem. SMACK utilizes a backward-filter, forward-smoother algorithm to solve the problem. The equations of motion are used to produce estimates that are compared with their corresponding measurement time histories. The procedure is iterative, providing improved state estimates until a minimum squared-error measure is achieved. In the SMACK program, the state and measurement models together represent a finite-difference approximation for the six-degree-of-freedom dynamics of a rigid body. The models are used to generate time histories which are likely to be found in a flight-test measurement set. These include onboard variables such as Euler angles, angular rates, and linear accelerations as well as tracking variables such as slant range, bearing, and elevation. Any bias or scale-factor errors associated with the state or measurement models are appended to the state vector and treated as constant but unknown parameters. The SMACK documentation covers the derivation of the solution algorithm, describes the state and measurement models, and presents several application examples that should help the analyst recognize the potential advantages of using state estimation. Complete instructions are given for preparing a coding list for problem solution by SMACK. The use of SMACK as part of an overall flight-test methodology is illustrated, as well as its application for analysis of a windshear accident. The details required for installing the program are presented, including sample output listings to facilitate testing. SMACK is written in FORTRAN 77 for DEC VAX series computers running VMS. Two versions of the source code are provided, a single precision version, which can be ported to Cray series computers, and a VAX double precision version. SMACK can call routines from the commercial package IMSL, or replacement routines which are provided can be used. SMACK solution variables to be plotted are written to an ASCII plot file. A sample plotting program, which is designed to be used with the DISSPLA graphics package, is included; however this program can easily be modified for use with other xy plotting packages. The double precision version requires 10Mb of RAM for execution under VMS. SMACK is available in DEC VAX BACKUP format on a 9-track 1600 BPI magnetic tape (standard distribution) or on a TK50 tape cartridge. This program was developed in 1991. DEC, VAX, and VMS are trademarks of Digital Equipment Corporation. DISSPLA is a trademark of Computer Associates, Inc. IMSL is a registered trademark of IMSL, Inc.

Bach, R.

1994-01-01

261

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

262

Highly damped kinematic coupling for precision instruments

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

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

2001-01-01

263

Kinematics of Diffuse Ionized Gas Halos

NASA Astrophysics Data System (ADS)

Existing long-slit spectral data for edge-on spiral galaxies suggesting that their Diffuse Ionized Gas (DIG) halos rotate slower than their underlying disks are summarized. An attempt to characterize lagging halos using a model of purely ballistic disk-halo flow is discussed, with the result that the model fails badly for the lagging halo of NGC 891, but is somewhat more successful for NGC 5775. New two-dimensional kinematic data on the DIG halo of NGC 4302 are presented, along with a preliminary analysis of its rotation. Two-dimensional data on NGC 5775 and a preliminary analysis of its halo rotation is discussed by Heald et al. (this volume). The halo of NGC 4302 shows clear signs of lagging on its approaching side, but also strong indications of peculiar kinematics. The kinematics of the receding side are more complex.

Rand, R. J.

2005-06-01

264

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

265

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

Recent published results in inverse scattering generally show the difficulty in dealing with moderate to high contrast inhomogeneities when employing linearized or iteratively linearized algorithms (e.g., distorted Born iterative method). This paper presents a fully nonlinear algorithm utilizing full wave field data, that results in ultrasound computed tomographic images from a laboratory breast scanner, and shows several such unique images from volunteer subjects. The forward problem, data collection process and inverse scattering algorithm used are discussed. A functional that represents the “best fit” between predicted and measured data is minimized, and therefore requires a very fast forward problem solver, Jacobian calculation, and gradient estimation, all of which are described. The data collection device is described. The algorithm and device yield quantitative estimates of human breast tissue in vivo. Several high resolution images, measuring ?150 by 150 wavelengths, obtained from the 2D inverse scattering algorithms, using data collected from a first prototype, are shown and discussed. The quantitative values are compared with previous published work.

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

2012-01-01

266

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

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

267

Kinematics of the M82 Starburst

NASA Astrophysics Data System (ADS)

We are continuing our study of the stellar kinematics in the starburst galaxy M82. We observed the 2.294 microns (2-0)(12) CO stellar absorption band across the central 30 arcseconds of M82 at a resolution of 20000 with the CSHELL echelle spectrometer on the 3m NASA IRTF on UT 7, 8, and 9 April 1993. With these data, we have measured the stellar kinematics of the central r<200 pc along the starburst disk. The velocity dispersion measured in our initial study (Gaffney et al. 1993, Ap. J. Letters, 407, L57) demonstrated that the stellar population in the central r<7.5 pc of M82 has a mass-to-light ratio consistent with that of a normal bulge. We interpret this as a nuclear population of old bulge stars surrounded by a ring of newly formed massive stars. By extending the spatial range of our measurements, we measure the mass of the stellar population surrounding the nucleus directly. With this, we will determine whether old giants or young supergiants dominate the near infrared continuum in the starburst disk. In addition to the stellar kinematics, we have measured the kinematics of the gas using both the 2.166 microns Brackett gamma hydrogen recombination line and the 1.644 microns [FeII] emission line. By comparing the stellar kinematics with the Brackett gamma and [FeII], we determine what effect shock and large scale gas flows have on the gas kinematics and morphology across the starburst disk.

Gaffney, Niall I.; Lester, Dan F.; Telesco, C. M.

1993-05-01

268

Kinematics and Control of Robot Manipulators

NASA Astrophysics Data System (ADS)

This dissertation focuses on the kinematics and control of robot manipulators. The contribution to kinematics is a fundamental theorem on the design of manipulators with six revolute joints. The theorem states, roughly speaking, that manipulators which have six revolute joints and are modeled after the human arm are optimal and essentially unique. In developing the mathematical framework to prove this theorem, we define precisely the notions of length of a manipulator, well-connected-workspace, and work-volume. We contribute to control a set of analysis techniques for the design of variable structure (sliding mode) controllers for manipulators. The organization of the dissertation is the following. After introductory remarks in chapter one, the group of proper rigid motions, G, is introduced in chapter two. The tangent bundle of G is introduced and it is shown that the velocity of a rigid body can be represented by an element in the Lie algebra of G (commonly called a twist). Further, rigid motions which are exponentials of twists are used to describe four commonly occurring subproblems in robot kinematics. In chapter three, the exponentials of twists are used to write the forward kinematic map of robot manipulators and the subproblems of chapter two are used to solve the Stanford manipulator and an elbow manipulator. Chapter four focuses on manipulator singularities. Twist coordinates are used to find critical points of the forward kinematic map. The contribution to kinematics is contained in chapter five where a mathematical framework for studying the relationship between the design of 6R manipulators and their performance is developed. Chapter seven contains the contribution to control. The work of A. F. Filippov on differential equations with discontinuous right-hand-side and the work of F. H. Clarke on generalized gradients are combined to obtain a calculus for analyzing nonsmooth gradient systems. The techniques developed are applied to design a simple variable structure controller for the nonlinear dynamics of robot manipulators.

Paden, Bradley Evan

269

Kinematic Issues of GPDs in DVCS

NASA Astrophysics Data System (ADS)

Generalized Parton Distributions (GPDs) in Deeply Virtual Compton Scattering (DVCS) have been widely recognized and used as a useful tool to explore the quark and gluon structure of the target hadrons. However, we recently pointed out treacherous kinematic issues in analyzing DVCS in terms of GPDs. We present our key findings in the simplest possible level of complete amplitude including the lepton current. We also discuss an implication on theoretical frameworks to cover the kinematic region of DVCS experiment with the 12 GeV upgrade at Jefferson Lab.

Ji, Chueng-Ryong; Bakker, Bernard L. G.

2014-06-01

270

Kinematic Transitions and Streams in Galaxy Halos

NASA Astrophysics Data System (ADS)

The chemo-dynamics of galaxy halos beyond the Local Group may now be mapped out through the use of globular clusters and planetary nebulae as bright tracer objects, along with deep multi-slit spectroscopy of the integrated stellar light. We present results from surveying nearby early-type galaxies, including evidence for kinematically distinct halos that may reflect two-phase galaxy assembly. We also demonstrate the utility of the tracer approach in measuring the kinematics of a stellar substructures around the Umbrella Galaxy, which allow us to reconstruct the progenitor properties and stream orbit.

Romanowsky, A. J.; Arnold, J. A.; Brodie, J. P.; Foster, C.; Forbes, D. A.; Lux, H.; Martínez-Delgado, D.; Strader, J.; Zibetti, S.; Sluggs Team

2014-05-01

271

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

272

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

273

Graph Theory Roots of Spatial Operators for Kinematics and Dynamics

NASA Technical Reports Server (NTRS)

Spatial operators have been used to analyze the dynamics of robotic multibody systems and to develop novel computational dynamics algorithms. Mass matrix factorization, inversion, diagonalization, and linearization are among several new insights obtained using such operators. While initially developed for serial rigid body manipulators, the spatial operators and the related mathematical analysis have been shown to extend very broadly including to tree and closed topology systems, to systems with flexible joints, links, etc. This work uses concepts from graph theory to explore the mathematical foundations of spatial operators. The goal is to study and characterize the properties of the spatial operators at an abstract level so that they can be applied to a broader range of dynamics problems. The rich mathematical properties of the kinematics and dynamics of robotic multibody systems has been an area of strong research interest for several decades. These properties are important to understand the inherent physical behavior of systems, for stability and control analysis, for the development of computational algorithms, and for model development of faithful models. Recurring patterns in spatial operators leads one to ask the more abstract question about the properties and characteristics of spatial operators that make them so broadly applicable. The idea is to step back from the specific application systems, and understand more deeply the generic requirements and properties of spatial operators, so that the insights and techniques are readily available across different kinematics and dynamics problems. In this work, techniques from graph theory were used to explore the abstract basis for the spatial operators. The close relationship between the mathematical properties of adjacency matrices for graphs and those of spatial operators and their kernels were established. The connections hold across very basic requirements on the system topology, the nature of the component bodies, the indexing schemes, etc. The relationship of the underlying structure is intimately connected with efficient, recursive computational algorithms. The results provide the foundational groundwork for a much broader look at the key problems in kinematics and dynamics. The properties of general graphs and trees of nodes and edge were examined, as well as the properties of adjacency matrices that are used to describe graph connectivity. The nilpotency property of such matrices for directed trees was reviewed, and the adjacency matrices were generalized to the notion of block weighted adjacency matrices that support block matrix elements. This leads us to the development of the notion of Spatial Kernel Operator SKO kernels. These kernels provide the basis for the development of SKO resolvent operators.

Jain, Abhinandan

2011-01-01

274

Kinetic and kinematic differences between deadlifts and goodmornings

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.

2013-01-01

275

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

276

National Technical Information Service (NTIS)

When we began our study of inverse procedures to determine ocean circulation, our intent was to build on past studies. It turned out, however, that much of the earlier work contained elements that were unclear so we were forced to begin again and to estab...

M. Fiadeiro G. Veronis

1986-01-01

277

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

2010-05-18

278

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

279

Inverse problem in hydrogeology

The state of the groundwater inverse problem is synthesized. Emphasis is placed on aquifer characterization, where modelers have to deal with conceptual model uncertainty (notably spatial and temporal variability), scale dependence, many types of unknown parameters (transmissivity, recharge, boundary conditions, etc.), nonlinearity, and often low sensitivity of state variables (typically heads and concentrations) to aquifer properties. Because of these difficulties,

Jesffls Carrera; Andrés Alcolea; Agustín Medina; Juan Hidalgo; Luit J. Slooten

2005-01-01

280

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

281

National Technical Information Service (NTIS)

The inverses of r-banded matrices, for r = 1, 2, 3 have been thoroughly investigated as one can see from the references we provide. Let Br,n (1 less than or equal to r less than or equal to n) be an n x n matrix of entries (ai sub j), -r less than or equa...

E. Kilic P. Stanica

2013-01-01

282

Calibration of parallel kinematic devices using sequential determination of kinematic parameters

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

283

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

284

Thermo-kinematical modelling of intracontinental inverted metamorphism: a 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 thrust in major orogens (e.g., Himalayas, Caledonian belt). Yet, in spite of numerous structural and petrological data, the origin of such a metamorphic inversion is still not really understood. Particularly, the relationship between the metamorphic events and the deformation is not well constrained even if many existing models propose that the metamorphic inversion result from a thermal inversion at crustal- scale. Hence, the conditions needed for such a geothermal perturbation are still not well defined. In addition, the preservation of the metamorphic inversion is also still debated. Here, we investigate the key-parameters and processes controlling the inversion of the geothermal gradient at crustal-scale by using a 2D-thermo-kinematical model. The velocity field (including isostasy compensation) is imposed in the whole model in order to simulate a crustal-scale thrust. At each time step, we solve the heat diffusion equation on the grid including radiogenic heat production and shear heating. The temperatures are then advected by markers following the velocity field. This model is voluntary simplified in order to control each parameter which allows us to test their influence on the geothermal inversion. We realised a parametric study to quantify the impact of the initial conditions (thrust angle and convergence velocity) and of the thermal properties of the rocks on the thermal evolution around such a major compressive shear zone. Our results, in good agreement with previous studies (e.g., England and Molnar, 1993) suggest that the kinematic framework strongly impacts the thermal evolution around the thrust, but we also show that, in these cases, the thermal inversion is never preserved over time. Erosion rate and thermal conductivity of rocks are two parameters that control the location in space of the thermal perturbation and its intensity, respectively. We also show that thermal conductivity needs to be used with caution in numerical models due to its temperature dependence. Finally, shear heating appears to be the only processus allowing the preservation of the thermal inversion until the steady state. However, since shear heating is strongly dependent on the shear zone viscosity, we discuss its relationship with the evolution of the shear-zone composition.

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

2013-04-01

285

NASA Astrophysics Data System (ADS)

Detrital thermochronometer data collected within foreland basins record the topographic, fault kinematic and erosional evolution of the source area and are especially useful in constraining the temporal evolution of orogen-scale exhumation rates. We use a modified version of the transient 3-D thermo-kinematic model Pecube (e.g., Braun, 2003) to predict thermal structure, exhumation pathways and detrital age distributions for the low temperature zircon fission track (ZFT) and muscovite Ar/Ar (MAr) thermochronometers. Multiple faults with variable geometry and velocity are constructed within the model, and the effect of fault kinematics on the thermal field through which rock particles cool is tested. Measured ZFT and MAr grain-age distributions from Mio-Pliocene Siwalik foreland basin sediments in central Nepal are compared to those predicted by the numerical model to assess the effect of potential kinematic variations of the central Himalaya between 20 Ma and the present-day. Recent studies suggest a deceleration of the convergence rate of India and Asia between 20 and 10 Ma (e.g., Molnar & Stock, 2009), which may correspond to a distinct decrease in measured exhumation rates in central Nepal around 16 Ma (e.g., Bernet et al, 2006). Inversions are carried out to determine the distribution of fault velocities, convergence rates and thermal parameters that best fit the detrital datasets in an attempt to constrain the thermo-kinematic model for central Nepal Himalaya.

Perry, C.; van der Beek, P.; Braun, J.; Robert, X.

2009-12-01

286

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

287

Physical Imagery: Kinematic versus Dynamic Models

Physical imagery occurs when people imagine one object causing a change to a second object. To make inferences through physical imagery, people must represent information that coordinates the interactions among the imagined objects. The current research contrasts two proposals for how this coordinating information is realized in physical imagery. In the traditional kinematic formulation, imagery transformations are coordinated by geometric

Daniel L. Schwartz

1999-01-01

288

The Kinematics of Contact and Grasp

The kinematics of contact describe the motion of a point of contact over the surfaces of two contacting objects in response to a relative motion of these objects. Using concepts from differential geometry, I derive a set of equations, called the contact equations, that embody this relationship. I employ the contact equations to design the following applications to be executed

David J. Montana

1988-01-01

289

Compton Effect with Non-Relativistic Kinematics

ERIC Educational Resources Information Center

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

Shivalingaswamy, T.; Kagali, B. A.

2011-01-01

290

Constrained tri-sphere kinematic positioning system

A scalable and adaptable, six-degree-of-freedom, kinematic positioning system is described. The system can position objects supported on top of, or suspended from, jacks comprising constrained joints. The system is compatible with extreme low temperature or high vacuum environments. When constant adjustment is not required a removable motor unit is available.

Viola, Robert J (Jackson, WY)

2010-12-14

291

Compound nucleus studies withy reverse kinematics

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

292

Exact Kinematic Analysis of pumping units

A new pumping unit Kinematic Analysis method was developed for the calculation of position, velocity, acceleration of the polished rod, and torque factors as functions of crank angle. This method can also be used to calculate the angular position, velocity and acceleration of any part of the pumping unit mechanism. It is more accurate than previous methods because it produces

Sivinos

1983-01-01

293

Stellar Kinematics in the Galactic Centre.

National Technical Information Service (NTIS)

The observations of the stellar kinematics in the central 8 pc of the Galaxy are presented. It is shown that the spectroscopy of the 2.3 microns CO absorption feature, in late type stars, yields the stellar velocity dispersion and the average stellar radi...

M. T. Mcginn K. Sellgren E. E. Becklin D. N. B. Hall

1989-01-01

294

ANALYTIC MODELING OF THE MORETON WAVE KINEMATICS

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

295

Relativistic Kinematics for Motion Faster Than Light.

National Technical Information Service (NTIS)

The use of conformal coordinates in relativistic kinematics is illustrated and a simple extension of the theory of motions faster than light is provided. An object traveling at a speed greater than light discloses its presence by appearing suddenly at a p...

R. T. Jones

1982-01-01

296

Kinematical Analysis of Underwater Walking and Running

The purpose of this study was to determine kinematical characteristics of underwater locomotion and to compare them with those of land locomotion. Six male subjects performed walking and running on both conventional and underwater treadmills. Both treadmill speeds increased incrementally starting from 0.56 m s 1 to 3.33 m s 1, the maximum speed of the underwater treadmill. The motion

Takeru Kato; Shohei Onishi; Kaoru Kitagawa

2001-01-01

297

Qualitative kinematics of planar robots: Intelligent connection

This paper proposes a qualitative representation for robot kinematics in order to close the gap, raised by the perception-action problem, with a focus on intelligent connection of qualitative states to their corresponding numeric data in a robotic system. First, qualitative geometric primitives are introduced by combining a qualitative orientation component and qualitative translation component using normalisation techniques. A position in

Honghai Liu; George Macleod Coghill; David J. Brown

2007-01-01

298

From kinematical geodesy to inertial positioning

When H. Moritz (1967, 1971) studied ``kinematical geodesy'' for the purpose of separation of gravitation and inertia, especially within combined accelerometer-gradiometer systems, it was hard to believe that within five years time inertial survey systems would be available, exactly operating according to his theoretical design. Here, we attempt to give a geodetic introduction into the fundamental equation of inertial positioning

E. W. Grafarend

1981-01-01

299

Kinematic-Wave Furrow Irrigation Model

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

Wynn R. Walker; Allan S. Humpherys

1983-01-01

300

DESIGN OF THE 'GRANIT' PARALLEL KINEMATIC MANIPULATOR

This work describes the development of the GRANIT parallel-kinematic robot. The robot endorses a multifunctional end effector, a stiff and precise device aimed at the assembly of heating coils for hairdryers. Such assembly task require repeatability and releability, therefore we developed a custom manipulator which has 4 degrees of freedom like a SCARA robot, although offering a superior rigidity and

Alessandro Tasora; Paolo Righettini; Steven Chatterton

301

KINEMATIC DISTANCE ASSIGNMENTS WITH H I ABSORPTION

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

302

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

303

Gait kinematics for a serpentine robot

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

Jim Ostrowski; Joel Burdick

1996-01-01

304

Expertise and attunement to kinematic constraints.

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

305

Use of Kinematic Constraint in Tracking Constant Speed Maneuvering Targets.

National Technical Information Service (NTIS)

The use of a kinematic constraint as a pseudomeasurement in the tracking of constant speed maneuvering targets is considered in this report. The kinematic constraint provides additional information about the target motion that can be processed as a pseudo...

W. D. Blair G. A. Watson A. T. Alouani

1991-01-01

306

Three-dimensional kinematics of hummingbird flight.

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

307

Kinematic Optimization in Birds, Bats and Ornithopters

NASA Astrophysics Data System (ADS)

Birds and bats employ a variety of advanced wing motions in the efficient production of thrust. The purpose of this thesis is to quantify the benefit of these advanced wing motions, determine the optimal theoretical wing kinematics for a given flight condition, and to develop a methodology for applying the results in the optimal design of flapping-wing aircraft (ornithopters). To this end, a medium-fidelity, combined aero-structural model has been developed that is capable of simulating the advanced kinematics seen in bird flight, as well as the highly non-linear structural deformations typical of high-aspect ratio wings. Five unique methods of thrust production observed in natural species have been isolated, quantified and thoroughly investigated for their dependence on Reynolds number, airfoil selection, frequency, amplitude and relative phasing. A gradient-based optimization algorithm has been employed to determined the wing kinematics that result in the minimum required power for a generalized aircraft or species in any given flight condition. In addition to the theoretical work, with the help of an extended team, the methodology was applied to the design and construction of the world's first successful human-powered ornithopter. The Snowbird Human-Powered Ornithopter, is used as an example aircraft to show how additional design constraints can pose limits on the optimal kinematics. The results show significant trends that give insight into the kinematic operation of natural species. The general result is that additional complexity, whether it be larger twisting deformations or advanced wing-folding mechanisms, allows for the possibility of more efficient flight. At its theoretical optimum, the efficiency of flapping-wings exceeds that of current rotors and propellers, although these efficiencies are quite difficult to achieve in practice.

Reichert, Todd

308

Earthquake source inversion with dense networks

NASA Astrophysics Data System (ADS)

Inversions of earthquake source slip from the recorded ground motions typically impose a number of restrictions on the source parameterization, which are needed to stabilize the inverse problem with sparse data. Such restrictions may include smoothing, causality considerations, predetermined shapes of the local source-time function, and constant rupture speed. The goal of our work is to understand whether the inversion results could be substantially improved by the availability of much denser sensor networks than currently available. The best regional networks have sensor spacing in the tens of kilometers range, much larger than the wavelengths relevant to key aspects of earthquake physics. Novel approaches to providing orders-of-magnitude denser sensing include low-cost sensors (Community Seismic Network) and space-based optical imaging (Geostationary Optical Seismometer). However, in both cases, the density of sensors comes at the expense of accuracy. Inversions that involve large number of sensors are intractable with the current source inversion codes. Hence we are developing a new approach that can handle thousands of sensors. It employs iterative conjugate gradient optimization based on an adjoint method and involves iterative time-reversed 3D wave propagation simulations using the spectral element method (SPECFEM3D). To test the developed method, and to investigate the effect of sensor density and quality on the inversion results, we have been considering kinematic and dynamic synthetic sources of several types: one or more Haskell pulses with various widths and spacings; scenarios with local rupture propagation in the opposite direction (as observed during the 2010 El Mayor-Cucapah earthquake); dynamic crack-like rupture, both subshear and supershear; and rupture that mimics supershear propagation by jumping along the fault. In each case, we produce the data by a forward SPECFEM3D calculation, choose the desired density of stations, filter the data to 1 Hz (since the bulk properties are not known at higher frequencies), add noise of the desired level, and then apply our inversion approach. The results indicate that dense networks (e.g., 1-km spacing) produce sharper images of the considered sources than sparse networks (e.g., 10-20 km spacing), with better amplitude recovery and better resolution with depth. This is true even when noiseless sparse networks are compared with noisy dense networks, provided that the standard deviations of noise do not exceed ~1% of the maximum earthquake source amplitude (e.g., 1 cm/s noise for 1 m/s Haskell source). Substantial qualitative improvements arise when features of relatively narrow spatial extent are included in the source, in which case the dense networks can reproduce the features whereas the sparse networks cannot. We will report on our current efforts to mathematically quantify the differences between the inversions of sparse and dense data and to incorporate the effect of errors in the bulk velocity model.

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

2012-12-01

309

Inverse Scattering via Skin Effect.

National Technical Information Service (NTIS)

We present a stable method for the inverse scattering problem of the Helmholtz equation in two dimensions. The algorithm requires single-frequency scattering data, and is an iterative procedure which resembles the process of layer-stripping. The inversion...

Y. Chen

1996-01-01

310

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

311

Electrochemically driven emulsion inversion

NASA Astrophysics Data System (ADS)

It is shown that emulsions stabilized by ionic surfactants can be inverted by controlling the electrical potential across the oil-water interface. The potential dependent partitioning of sodium dodecyl sulfate (SDS) was studied by cyclic voltammetry at the 1,2-dichlorobenzene|water interface. In the emulsion the potential control was achieved by using a potential-determining salt. The inversion of a 1,2-dichlorobenzene-in-water (O/W) emulsion stabilized by SDS was followed by conductometry as a function of added tetrapropylammonium chloride. A sudden drop in conductivity was observed, indicating the change of the continuous phase from water to 1,2-dichlorobenzene, i.e. a water-in-1,2-dichlorobenzene emulsion was formed. The inversion potential is well in accordance with that predicted by the hydrophilic-lipophilic deviation if the interfacial potential is appropriately accounted for.

Johans, Christoffer; Kontturi, Kyösti

2007-09-01

312

We present a fast, non-iterative technique for producinggrayscale images from error di#used and dithered halftones.The #rst stage of the algorithm consists of a Gaussian #lterand a median #lter, while the second stage consistsof a bandpass #lter, a thresholding operation, and a median#lter. The second stage enhances the rendering ofedges in the inverse halftone. We compare our algorithmto the best reported

Niranjan Damera-venkata; Thomas D. Kite; Mahalakshmi Venkataraman; Brian L. Evans

1998-01-01

313

High Performance Inverse Preconditioning

The derivation of parallel numerical algorithms for solving sparse linear systems on modern computer systems and software\\u000a platforms has attracted the attention of many researchers over the years. In this paper we present an overview on the design\\u000a issues of parallel approximate inverse matrix algorithms, based on an anti-diagonal “wave pattern” approach and a “fish-bone”\\u000a computational procedure, for computing explicitly

George A. Gravvanis

2009-01-01

314

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

315

NSDL National Science Digital Library

"Lesson 1 of two lessons teaches students about direct variation by allowing them to explore a simulated oil spill using toilet paper tissues (to represent land) and drops of vegetable oil (to simulate a volume of oil). Lesson 2 teaches students about inverse variation by exploring the relationship between the heights of a fixed amount of water poured into cylindrical containers of different sizes as compared to the area of the containers' bases." from Insights into Algebra 1 - Annenberg Foundation.

Media, Annenberg

2009-12-23

316

Surface active inverse micelles

Surface tension of solutions of a commercial non-ionic surfactant, Laureth 4, and two hydrocarbons, decane and hexadecane,\\u000a with added water, was determined using a de Nouy ring. The results showed a reduction of surface tension with added water,\\u000a confirming an earlier suggestion of surface activity of inverse micelles. The surface activity is ascribed to the orientation\\u000a of the hydrocarbon chains

Stig E. Friberg; Abeer Al Bawab; Ahmad A. Abdoh

2007-01-01

317

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

ERIC Educational Resources Information Center

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

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

2011-01-01

318

Learning Kinematics with a V-Scope: A Case Study

NSDL National Science Digital Library

Studies the effect of V-Scope activities on the performance of 11th-grade students in analyzing kinematics graphs. Students were challenged to construct different kinds of graphs using their own movements as well as the motion of a dynamics cart. Results indicate that the V-Scope kinematics laboratory activities can promote kinematics concepts and graphing skills.

Trumper, Ricardo

2006-10-11

319

Learning Kinematics with a V-Scope: A Case Study.

ERIC Educational Resources Information Center

Studies the effect of V-Scope activities on the performance of 11th-grade students in analyzing kinematics graphs. Students were challenged to construct different kinds of graphs using their own movements as well as the motion of a dynamics cart. Results indicate that the V-Scope kinematics laboratory activities can promote kinematics concepts and…

Trumper, Ricardo

1997-01-01

320

SOME RESULTS ON INVERSE SCATTERING

A review of some of the author's results in the area of inverse scattering is\\u000agiven. The following topics are discussed: 1) Property $C$ and applications, 2)\\u000aStable inversion of fixed-energy 3D scattering data and its error estimate, 3)\\u000aInverse scattering with ''incomplete`` data, 4) Inverse scattering for\\u000ainhomogeneous Schr\\\\\\

A. G. RAMM

2008-01-01

321

NASA Astrophysics Data System (ADS)

A FORTRAN 77 computer code is presented that permits the inversion of Slingram electromagnetic anomalies to an optimal conductor model. Damped least-squares inversion algorithm is used to estimate the anomalous body parameters, e.g. depth, dip and surface projection point of the target. Iteration progress is controlled by maximum relative error value and iteration continued until a tolerance value was satisfied, while the modification of Marquardt's parameter is controlled by sum of the squared errors value. In order to form the Jacobian matrix, the partial derivatives of theoretical anomaly expression with respect to the parameters being optimised are calculated by numerical differentiation by using first-order forward finite differences. A theoretical and two field anomalies are inserted to test the accuracy and applicability of the present inversion program. Inversion of the field data indicated that depth and the surface projection point parameters of the conductor are estimated correctly, however, considerable discrepancies appeared on the estimated dip angles. It is therefore concluded that the most important factor resulting in the misfit between observed and calculated data is due to the fact that the theory used for computing Slingram anomalies is valid for only thin conductors and this assumption might have caused incorrect dip estimates in the case of wide conductors.

Dondurur, Derman; Sar?, Co?kun

2004-07-01

322

Intersections, ideals, and inversion

Techniques from computational algebra provide a framework for treating large classes of inverse problems. In particular, the discretization of many types of integral equations and of partial differential equations with undetermined coefficients lead to systems of polynomial equations. The structure of the solution set of such equations may be examined using algebraic techniques.. For example, the existence and dimensionality of the solution set may be determined. Furthermore, it is possible to bound the total number of solutions. The approach is illustrated by a numerical application to the inverse problem associated with the Helmholtz equation. The algebraic methods are used in the inversion of a set of transverse electric (TE) mode magnetotelluric data from Antarctica. The existence of solutions is demonstrated and the number of solutions is found to be finite, bounded from above at 50. The best fitting structure is dominantly onedimensional with a low crustal resistivity of about 2 ohm-m. Such a low value is compatible with studies suggesting lower surface wave velocities than found in typical stable cratons.

Vasco, D.W.

1998-10-01

323

NASA Astrophysics Data System (ADS)

In present-day forward time stepping ocean-climate models, capturing both the wind-driven and thermohaline components, a substantial amount of CPU time is needed in a so-called spin-up simulation to determine an equilibrium solution. In this paper, we present methodology based on Jacobian-Free Newton-Krylov methods to reduce the computational time for such a spin-up problem. We apply the method to an idealized configuration of a state-of-the-art ocean model, the Modular Ocean Model version 4 (MOM4). It is shown that a typical speed-up of a factor 10-25 with respect to the original MOM4 code can be achieved and that this speed-up increases with increasing horizontal resolution.

Bernsen, Erik; Dijkstra, Henk A.; Thies, Jonas; Wubs, Fred W.

2010-10-01

324

NASA Astrophysics Data System (ADS)

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

Platonov, V. P.

2014-02-01

325

NASA Astrophysics Data System (ADS)

The reasons to study the Algerian margin (Western Mediterranean) are at least threefold: (1) the seismic hazard offshore is obviously present but unconstrained, (2) the way the opening of the Algerian basin occurred is highly debated, and (3) this margin represents one of the rare examples on Earth of an ongoing subduction inception. We present an overview of recent findings on the tectonic evolution of this margin, where most of the plate convergence between Africa and Europe is taken up today, mostly from cruises MARADJA and MARADJA2/SAMRA led by joint Algerian and French teams. Large, overlapping active thrust faults and folds apparently dominate the seismotectonic pattern from the Atlas domain on land to the foot of the margin offshore, with a clear segmentation. Strain is distributed across the whole area, with a significant part of the relative plate convergence taken up offshore. Fault activity offshore is tenuous and most often indirect (Plio-Quaternary growth strata, folds, uplifted basins, scars and slope breaks). Along the eastern margin, faults form stepwise, en-échelon systems on the slope and in the deep basin. Some thrusts identified turn to fault-propagation folds at the sub-surface. Thrusts interact with the sediment flux, Messinian salt and seafloor currents, forming complex structures at deep-sea fans and scarps or scars on the main slope breaks. The 2003 Mw 6.9 Boumerdes rupture is correlated segmented cumulative scarps on the slope and at the foot of the margin. Using various VHR seismic reflection and coring analyses, we show that the record of turbidite deposition since ca. 10.000 yrs can be identified and correlated over long distances within or across large segments of the margin affected by the 1954, 1980 and 2003 events. The consequences in term of earthquake size and recovery of their recurrences (identification of paleo-events) are explored and discussed. Although we cannot associate the triggering of large turbidity currents to a given fault, we find that the Algerian margin gathers favourable conditions to reconstruct times series of turbidites associated to significant earthquakes. Finally, we show that the structures inherited from the Algerian basin opening and from the Alpine belt building (AlKaPeCa blocks migration and collision) determine for a large part the size, style and location of this strain pattern. The overall geometry indicates the predominance of back thrusts, implying underthrusting of the young oceanic crust, although large dextral strike-slip structures may guide deformation at some places on land. The recent (probably less than 3 Ma) reactivation of the Algerian margin is strongly influenced by the subduction of the Tethyan Maghrebian ocean, implying not only an important roll-back of the slab, but also strong thermal, magmatic and isostatic effects of the slab evolution at depth.

Deverchere, J.; Yelles, K.; Bracene, R.; Mercier de Lepinay, B. F.; Cattaneo, A.; Medaouri, M.; Gaullier, V.; Babonneau, N.; Ratzov, G.; Boudiaf, A.; Graindorge, D.; Kherroubi, A.; Strzerzynski, P. H.; Authemayou, C.; Djellit, H.; Heddar, A.; Maradja'03; Maradja-Samra'05 Scientific Teams

2011-12-01

326

Inverse Kinematics Algorithm for a Highly Redundant Variable-Geometry-Truss Manipulator.

National Technical Information Service (NTIS)

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 de...

F. Naccarato P. Hughes

1989-01-01

327

A novel framework for closed-loop robotic motion simulation - part I: Inverse kinematics design

This paper considers the problem of realizing a 6-DOF closed-loop motion simulator by exploiting an anthropomorphic serial manipulator as motion platform. Contrary to standard Stewart platforms, an industrial anthropomorphic manipulator offers a considerably larger motion envelope and higher dexterity that let envisage it as a viable and superior alternative. Our work is divided in two papers. In this Part I,

Paolo Robuffo Giordano; Carlo Masone; Joachim Tesch; Martin Breidt; Lorenzo Pollini; Heinrich H. Bülthoff

2010-01-01

328

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

329

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.

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

2010-01-01

330

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

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.

Leclercq, Guillaume; Lefevre, Philippe; Blohm, Gunnar

2013-01-01

331

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

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

2013-09-01

332

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

333

Identification of top quarks using kinematic variables

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

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

1995-09-01

334

Kinematic misalignments in remnants of multiple mergers

NASA Technical Reports Server (NTRS)

Observations indicate that the rotation and minor axes in elliptical galaxies are usually well aligned. However, computer models of dissipationless mergers of pairs of disk galaxies have failed to establish such a correlation, implying that most ellipticals probably did not originate in this manner. Here we consider remnants produced from repeated merging in small groups of a half-dozen or so disk galaxies and find that the internal kinematics of such objects are more representative of actual elliptical galaxies. Although our coverage of parameter space is not complete, the remnants produced in our simulations invariably possess small kinematic misalignments. These results suggest that the majority of elliptical galaxies have had evolutionary histories more complex than those envisaged by simple merger hypotheses.

Weil, Melinda L.; Hernquist, Lars

1994-01-01

335

Underwater Rockfall Kinematics: A Preliminary Analysis

\\u000a The marine environment presents various settings in which talus slopes are formed via a rock fall process similar to what\\u000a exists on land. This is the case along fjords and submarine canyons in particular. Although many studies have been carried\\u000a out on land, surprisingly very little is known for the submarine environment. We propose here the first kinematics analysis\\u000a of

Jacques Locat; D. Turmel

336

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

337

A kinematic model of a ducted flame

A premixed ducted flame, burning in the wake of a bluff-body flame-holder, is considered. For such a flame, interaction between acoustic waves and unsteady combustion can lead to self-excited oscillations. The concept of a time-invariant turbulent flame speed is used to develop a kinematic model of the response of the flame to flow disturbances. Variations in the oncoming flow velocity

A. P. Dowling

1999-01-01

338

From kinematical geodesy to inertial positioning

WhenH. Moritz (1967, 1971) studied “kinematical geodesy” for the purpose of separation of gravitation and inertia, especially within combined\\u000a accelerometer-gradiometer systems, it was hard to believe that within five years time inertial survey systems would be available,\\u000a exactly operating according to his theoretical design. Here, we attempt to give a geodetic introduction into the fundamental\\u000a equation of inertial positioning materialized

E. W. Grafarend

1981-01-01

339

Quantum kinematics of spacetime. I. Nonrelativistic theory

NASA Astrophysics Data System (ADS)

The sum-over-histories quantum mechanics of a nonrelativistic particle gives a spacetime formulation of that theory in which the preferred Newtonian time does not enter immediately into the quantum kinematics. We investigate on what spacetime hypersurfaces a Schrödinger-Heisenberg formulation of the theory can be recovered and conclude that, in general, this is possible only on the surfaces of constant preferred Newtonian time. The significance of this for a quantum theory of spacetime is discussed.

Hartle, J. B.

1988-05-01

340

High precision kinematic surveying with laser scanners

NASA Astrophysics Data System (ADS)

The kinematic survey of roads and railways is becoming a much more common data acquisition method. The development of the Mobile Road Mapping System (MoSES) has reached a level that allows the use of kinematic survey technology for high precision applications. The system is equipped with cameras and laser scanners. For high accuracy requirements, the scanners become the main sensor group because of their geometric precision and reliability. To guarantee reliable survey results, specific calibration procedures have to be applied, which can be divided into the scanner sensor calibration as step 1, and the geometric transformation parameter estimation with respect to the vehicle coordinate system as step 2. Both calibration steps include new methods for sensor behavior modeling and multisensor system integration. To verify laser scanner quality of the MoSES system, the results are regularly checked along different test routes. It can be proved that a standard deviation of 0.004 m for height of the scanner points will be obtained, if the specific calibrations and data processing methods are applied. This level of accuracy opens new possibilities to serve engineering survey applications using kinematic measurement techniques. The key feature of scanner technology is the full digital coverage of the road area. Three application examples illustrate the capabilities. Digital road surface models generated from MoSES data are used, especially for road surface reconstruction tasks along highways. Compared to static surveys, the method offers comparable accuracy at higher speed, lower costs, much higher grid resolution and with greater safety. The system's capability of gaining 360 profiles leads to other complex applications like kinematic tunnel surveys or the precise analysis of bridge clearances.

Gräfe, Gunnar

2007-12-01

341

Kinematical Test Theories for Special Relativity

NASA Astrophysics Data System (ADS)

A comparison of certain kinematical test theories for Special Relativity including the Robertson and Mansouri-Sext test theories is presented and the accuracy of the experimental results testing Special Relativity are expressed in terms of the parameters appearing in these test theories. The theoretical results are applied to the most precise experimental results obtained recently for the isotropy of light propagation and the constancy of the speed of light.

Lämmerzahl, Claus; Braxmaier, Claus; Dittus, Hansjörg; Müller, Holger; Peters, Achim; Schiller, Stephan

342

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

343

Multiscale full waveform inversion

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

344

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.

345

Phonovibrographic wavegrams: visualizing vocal fold kinematics.

Recently, endoscopic high-speed laryngoscopy has been established for commercial use as a state-of-the-art technique to examine vocal fold kinematics. Since modern cameras provide sampling rates of several thousand frames per second, a high volume of data has to be considered for visual and objective analysis. A method for visualizing endoscopic high speed videos in three-dimensional cycle-based graphs combining and extending the approaches of phonovibrograms and electroglottographic wavegrams is presented. To build a phonovibrographic wavegram, individual cycles of a phonovibrogram are segmented, normalized in cycle duration, and concatenated over time. For analyzing purposes, the emerging three-dimensional scalar field is visualized with different rendering techniques providing information of different aspects of vocal fold kinematics. The phonovibrographic wavegram incorporates information about the glottal closure type, size, and location of the amplitudes, symmetry, periodicity, and phase information. The potential of the approach to visualize the characteristics of vocal fold vibration in a compact and intuitive way is demonstrated within two healthy and three pathologic subjects. The phonovibrographic wavegram allows a comprehensive analysis of vocal fold kinematics and reveals information that remains hidden with other visualization techniques. PMID:23363121

Unger, Jakob; Meyer, Tobias; Herbst, Christian T; Fitch, W Tecumseh S; Döllinger, Michael; Lohscheller, Jörg

2013-02-01

346

New Kinematical Constraints on Cosmic Acceleration

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

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

2007-05-25

347

Dynamic control of kinematically redundant manipulators

NASA Astrophysics Data System (ADS)

A robot manipulator is said to be kinematically redundant when it has more degrees of freedom than are necessary to accomplish a particular task. Useful control strategies are designed for kinematically redundant manipulators in order to enhance their performance. Following the impedance control approach, the problem of minimizing redundant manipulator collision impacts is addressed. The configuration control approach is used to reduce impulsive forces, while a simplified impedance control scheme is formulated to minimize rebound effects. A new Cartesian control strategy for redundant flexible-joint manipulators is proposed. The main idea in this hybrid scheme is to control not only the manipulator's end-effector but also its links, so as to achieve specified positions and velocities for the end-effector and the links. Finally, a new application of kinematically redundant manipulators is proposed: using redundancy resolution to compensate for joint flexibility. This redundancy resolution scheme is incorporated in a control strategy for redundant flexible-joint manipulators. The problem of possible algorithmic singularities is considered, and a scheme is suggested which makes the controller robust with respect to such singularities.

Lin, Zhengcheng

1993-03-01

348

Kinematics of envelopes around First Core Candidates

NASA Astrophysics Data System (ADS)

Simulations of star formation predict the formation of a young object that reaches hydrostatic equilibrium before the formation of the protostar. This first hydrostatic core which is a flattened, thermally supported structure with a size of a few AU will collapse after up to 10,000 years to form a second object in hydrostatic equilibrium, namely a (Class 0) protostar. We are studying a sample of eight first core candidates that have been identified as such based on the detection of a point source millimeter continuum emission very weak, or no continuum emission at ?<24 ?m and/or the presence of a low velocity outflow. Here, we present CARMA (NH2D, N2H+, HCO+, HCN) and ALMA (N2H+) molecular lines emission maps at a resolution of 500 to 1000 AU. At this scale we are able to study the kinematic and morphology of the dense envelope surrounding the first core candidates. The data show presence of infall and rotation. We study the kinematics of these sources by modeling the profile of the lines. We are studying the kinematics of these sources using a simple radiative transfer model. The data show presence of infall and rotation, and we aim to constrain the mass inside the resolution limit by modeling the velocity distribution of each envelope. This, along other properties (e.g., density profile, SED, level of deuteration) will help us constrain the evolutionary stage of these sources.

Maureira, Maria Jose; Arce, Hector G.

2014-07-01

349

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

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

350

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

The inverse and forward dynamics problems for multilink 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 similar to the equations of Kalman filtering and Bryson-Frazier fixed time-interval smoothing.

G. Rodriguez

1987-01-01

351

On the footprint of anisotropy on isotropic full waveform inversion: the Valhall case study

The validity of isotropic approximation to perform acoustic full waveform inversion (FWI) of real wide-aperture anisotropic data can be questioned due to the intrinsic kinematic inconsistency between short- and large-aperture components of the data. This inconsistency is mainly related to the differences between the vertical and horizontal velocities in vertical-transverse isotropic (VTI) media. The footprint of VTI anisotropy on 2-D

Vincent Prieux; Romain Brossier; Yaser Gholami; Stéphane Operto; Jean Virieux; O. I. Barkved; J. H. Kommedal

2011-01-01

352

Migration/inversion: think image point coordinates, process in acquisition surface coordinates

NASA Astrophysics Data System (ADS)

We state a general principle for seismic migration/inversion ({\\sf M/I}) processes: think image point coordinates; compute in surface coordinates. This principle allows the natural separation of multiple travel paths of energy from a source to a reflector to a receiver. Further, the Beylkin determinant (Jacobian of transformation between processing parameters and acquisition surface coordinates) is particularly simple in stark contrast to the common-offset Beylkin determinant in standard single arrival Kirchhoff {\\sf M/I} . A feature of this type of processing is that it changes the deconvolution structure of Kirchhoff {\\sf M/I} operators or the deconvolution imaging operator of wave equation migration into convolution operators; that is, division by Green's functions is replaced by multiplications by adjoint Green's functions. This transformation from image point coordinates to surface coordinates is also applied to a recently developed extension of the standard Kirchhoff inversion method. The standard method uses {\\sf WKBJ} Green's functions in the integration process and tends to produce more imaging artefacts than alternatives, such as methods using Gaussian beam representations of Green's functions in the inversion formula. These methods point to the need for a true-amplitude Kirchhoff technique that uses more general Green's functions: Gaussian beams, true-amplitude one-way Green's functions, or Green's functions from the two-way wave equation. Here, we present a derivation of a true-amplitude Kirchhoff {\\sf M/I} that uses these more general Green's functions. When this inversion is recast as an integral over all sources and receivers, the formula is surprisingly simple.

Bleistein, Norman; Zhang, Yu; Xu, Sheng; Zhang, Guanquan; Gray, Samuel H.

2005-10-01

353

Influence of kinematic redundancy on the singularity-free workspace of parallel kinematic machines

NASA Astrophysics Data System (ADS)

In this paper the effect of kinematic redundancy in order to reduce the singularity loci of the direct kinematics and to increase the operational, i.e., singularityfree, workspace is demonstrated. The proposed approach consists of additional prismatic actuators allowing one or more base joints to move linearly. As a result, a selective reconfiguration can be performed in order to avoid singular configurations. Exemplarily, kinematically redundant schemes of four structures, the 3 RRR, the 3R PR, the 6U PS, and the 6 RUS, are considered. The relationship between the redundancy and the operational workspace is studied and several analysis examples demonstrate the effectiveness of the proposed concept. Furthermore, the additional benefit of an increasing number of redundant actuators is discussed.

Kotlarski, Jens; Heimann, Bodo; Ortmaier, Tobias

2012-06-01

354

Summary Biomechanics and neurophysiology studies suggest whole limb function to be an important locomotor control parameter. Inverted pendulum and mass-spring models greatly reduce the complexity of the legs and predict the dynamics of locomotion, but do not address how numerous limb elements are coordinated to achieve such simple behavior. As a first step, we hypothesized whole limb kinematics were of primary importance and would be preferentially conserved over individual joint kinematics after neuromuscular injury. We used a well-established peripheral nerve injury model of cat ankle extensor muscles to generate two experimental injury groups with a predictable time course of temporary paralysis followed by complete muscle self-reinnervation. Mean trajectories of individual joint kinematics were altered as a result of deficits after injury. By contrast, mean trajectories of limb orientation and limb length remained largely invariant across all animals, even with paralyzed ankle extensor muscles, suggesting changes in mean joint angles were coordinated as part of a long-term compensation strategy to minimize change in whole limb kinematics. Furthermore, at each measurement stage (pre-injury, paralytic and self-reinnervated) step-by-step variance of individual joint kinematics was always significantly greater than that of limb orientation. Our results suggest joint angle combinations are coordinated and selected to stabilize whole limb kinematics against short-term natural step-by-step deviations as well as long-term, pathological deviations created by injury. This may represent a fundamental compensation principle allowing animals to adapt to changing conditions with minimal effect on overall locomotor function.

Chang, Young-Hui; Auyang, Arick G.; Scholz, John P.; Nichols, T. Richard

2009-01-01

355

Inverses of finite group systems

Inverse systems are considered for a class of discrete time-invariant systems that include the finite linear sequential circuits (LSC's). Invertibility results for finite group homomorphic sequential systems (FGHSS's), given by Willsky [8], are extended to include systems with throughput A construction is developed for anL-delay inverse of any FGHSS that is invertible withLgeq0delays. This inverse is always a discrete time-invariant

H. Chizeck

1978-01-01

356

Inverse Problems in Wave Propagation

Abstract. The refraction,inverse problem,was,initially investigated,by Herglotz (1907), Bateman (1910), and Wiechert and Geiger (1910) who applied Abel transforms for the inversion of seismic travel-times in radially varying,media. For smoothly,varying media in the absence of low velocity zones, this formulation provides an inverse solution which includes ray bending. In the presence of low velocity zones, bounds on the solu tion can

George Papanicolaou; ROBERT L. NOWACK

357

Time to reconcile thermal inversion models around thrusts

NASA Astrophysics Data System (ADS)

Inversion of metamorphic thermal isograds is commonly observed around mega-thrusts, particularly in close association with major thrusts in collision belts. However, the processes leading to such thermal inversion still constitute an open issue. Various models have already addressed their possible syn-deformational origin during thrusting. However, because they concentrated on specific contexts and processes, none of these models has achieved a general consensus. Hence, in order to reconcile these different models of syn-deformational thermal inversion, it becomes crucial to find a way allowing to determine the key process controlling the thermal evolution for any thrust zone. Here, we present a dimensional analysis allowing to quantify the relative control of heat diffusion, advection and shear heating on the thermal evolution around thrusts. Our analytical solution invokes parameters that can define any thrust scenario in terms of kinematics, rheological strength and thermal context. Our study focuses mainly on the role of the thrust thickness, h, the shear zone dip angle, ?, the convergence velocity, V, and the effective viscosity, ?, of the shear zone. Our dimensional analysis shows that for typical values applicable to intracontinental thrusts (h = 1-5 km, ? = 15-45°, V = 1-3 cm/yr, ? = 1e19-1e21 Pa.s) heat diffusion as well as advection as well as shear heating can be the dominant process controlling the thermal evolution around thrusts. This result explains the difficulty of finding a unique model for inverted metamorphism. From this, we first validate our dimensional analysis with two-dimensional thermo- kinematical models: for typical values and scenarios applicable to different thrusts, our numerical results show specific thermal evolutions. Then, we apply our first-order coupled analytical-numerical method to natural occurrences of inverted zonation of metamorphic peak temperatures. In this way, our analysis suggests that the inverted metamorphism associated to the Main Central Thrust in the Himalayas, for instance, can be mainly a result of shear heating.

Duprat-Oualid, Sylvia; Yamato, Philippe; Schmalholz, Stefan M.

2014-05-01

358

NASA Technical Reports Server (NTRS)

One of the most fundamental physical properties of any asteroid is its shape. Lightcurves provide the only source of shape information for most asteroids. Unfortunately, the functional form of a lightcurve is determined by the viewing/illumination geometry and the asteroid's light scattering characteristics as well as its shape, and in general it is impossible to determine an asteroid's shape from lightcurves. A technique called convex-profile inversion (CPI) that obtains a convex profile, P, from any lightcurve is introduced. If certain ideal conditions are satisfied, then P is an estimator for the asteroid's mean cross section, C, a convex set defined as the average of all cross sections C(z) cut by planes a distance z above the asteroids's equatorial plane. C is therefore a 2-D average of the asteroid's 3-D shape.

Ostro, Steven J.; Connelly, Robert

1987-01-01

359

Wavelet Sparse Approximate Inverse Preconditioners

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

360

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

361

NASA Astrophysics Data System (ADS)

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 Lagrangian approach is used in formulating the equations of 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.

Ledesma, Ragnar; Bayo, Eduardo

1993-08-01

362

Uncertainty Propagation in Calibration of Parallel Kinematic Machines

Over the last decade, multi-axis machine tools and robots based on parallel kinematic mechanisms (PKMs) have been developed and marketed worldwide. Positional accuracy in these machines is controlled by accurate knowledge of the kinematic parameters which consists of the joint center locations and distances between joint pairs. Since these machines tend to be rather large in size, the kinematic parameters (joint center locations, and initial strut lengths) are difficult to determine when these machines are in their fully assembled state. Work recently completed by the University of Florida and Sandia National Laboratories has yielded a method for determining all of the kinematic parameters of an assembled parallel kinematic device. This paper contains a brief synopsis of the calibration method created, an error budget, an uncertainty analysis for the recovered kinematic parameters and the propagation of these uncertainties to the tool tip.

JOKIEL JR.,BERNHARD; ZIERGERT,JOHN C.

1999-11-02

363

Physics Suite Peer Instruction Problems: Kinematics

NSDL National Science Digital Library

This website contains a series of peer instruction problems on kinematics, designed to be solved in a classroom setting. The problems are presented with a qualitative (usually multiple choice) question that is carefully constructed to engage student difficulties with fundamental concepts. Students consider the problem individually and contribute their answers using personal response systems (clickers). Students then confer with their cooperative groups and vote again on the correct response. Topics covered include displacement, velocity, average velocity, speed, and interpreting position and velocity graphs. This problem set is part of the Physics Suite collection, containing sample problems, peer instruction problems, and alternative homework sets.

Redish, Edward F.

2008-08-11

364

Kinematical and mechanical aspects of wafer slicing

NASA Technical Reports Server (NTRS)

Some recently achieved results concerning the technological fundamentals of slurry sawing are presented. The specific material removal process and the related kinematic and geometric contact conditions between workpiece and saw blade are described. The result of a functional description of the slurry sawing process is presented, expressing the main process criteria, such as infeed per stroke, specific removal rate, specific tool wear, and vertical stroke intensity, in terms of the dominating process parameters, such as stroke length, width of workpiece, stroke frequency, specific cutting force and slurry specification.

Werner, P. G.

1982-01-01

365

Optimal kinematics and morphologies for spermatozoa.

We investigate the role of hydrodynamics in the evolution of the morphology and the selection of kinematics in simple uniflagellated microorganisms. We find that the most efficient swimming strategies are characterized by symmetrical, nonsinusoidal bending waves propagating from the base of the head to the tip of the tail. In addition, we show that the ideal tail-to-head length ratio for such a swimmer is ?12 and that this predicted ratio is consistent with data collected from over 400 species of mammalian sperm. PMID:21599231

Tam, Daniel; Hosoi, A E

2011-04-01

366

Kinematic reversal schemes for the geomagnetic dipole.

NASA Technical Reports Server (NTRS)

Fluctuations in the distribution of cyclonic convective cells, in the earth's core, can reverse the sign of the geomagnetic field. Two kinematic reversal schemes are discussed. In the first scheme, a field maintained by cyclones concentrated at low latitude is reversed by a burst of cyclones at high latitude. Conversely, in the second scheme, a field maintained predominantly by cyclones in high latitudes is reversed by a fluctuation consisting of a burst of cyclonic convection at low latitude. The precise fluid motions which produce the geomagnetic field are not known. However, it appears that, whatever the details are, a fluctuation in the distribution of cyclonic cells over latitude can cause a geomagnetic reversal.

Levy, E. H.

1972-01-01

367

Estimation methods for GPS kinematic data processing

NASA Astrophysics Data System (ADS)

The characteristics of three GPS kinematical data processing models, Least Square, Kalman filtering, and Semiparametric model are discussed and their advantages and disadvantages are compared. With observational data and pertinent data processing software, the applicable condition, context and effect of the three models are experimented. Results show that when the mobile platform is in uniform motion, the accuracy of the three models are almost equal; when the mobile platform is in stochastic acceleration, the accuracy of Semiparametric model is superior to that of LS, and that of Kalman filtering is the worst.

Chen, Gang; Pan, Xiong

2009-07-01

368

The kinematic cooling of molecules with laser-cooled atoms

NASA Astrophysics Data System (ADS)

We propose a new scheme for the production of milli-Kelvin molecules via kinematic cooling through collisions with atoms in a magneto-optical trap (MOT). We will discuss the kinematic conditions necessary for producing cold molecules, the limits of the final attainable temperatures and the experimental implementation of this technique. Finally, we will look at some specific physical systems and discuss the effectiveness of kinematic cooling inside a MOT.

Takase, Ken; Rahn, Larry A.; Chandler, David W.; Strecker, Kevin E.

2009-05-01

369

Kinematic Design to Improve Ergonomics in Human Machine Interaction

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

370

Earthquake Source Inversion Blindtest: Initial Results and Further Developments

NASA Astrophysics Data System (ADS)

Images of earthquake ruptures, obtained from modelling/inverting seismic and/or geodetic data exhibit a high degree in spatial complexity. This earthquake source heterogeneity controls seismic radiation, and is determined by the details of the dynamic rupture process. In turn, such rupture models are used for studying source dynamics and for ground-motion prediction. But how reliable and trustworthy are these earthquake source inversions? Rupture models for a given earthquake, obtained by different research teams, often display striking disparities (see http://www.seismo.ethz.ch/srcmod) However, well resolved, robust, and hence reliable source-rupture models are an integral part to better understand earthquake source physics and to improve seismic hazard assessment. Therefore it is timely to conduct a large-scale validation exercise for comparing the methods, parameterization and data-handling in earthquake source inversions.We recently started a blind test in which several research groups derive a kinematic rupture model from synthetic seismograms calculated for an input model unknown to the source modelers. The first results, for an input rupture model with heterogeneous slip but constant rise time and rupture velocity, reveal large differences between the input and inverted model in some cases, while a few studies achieve high correlation between the input and inferred model. Here we report on the statistical assessment of the set of inverted rupture models to quantitatively investigate their degree of (dis-)similarity. We briefly discuss the different inversion approaches, their possible strength and weaknesses, and the use of appropriate misfit criteria. Finally we present new blind-test models, with increasing source complexity and ambient noise on the synthetics. The goal is to attract a large group of source modelers to join this source-inversion blindtest in order to conduct a large-scale validation exercise to rigorously asses the performance and reliability of current inversion methods and to discuss future developments.

Mai, P.; Burjanek, J.; Delouis, B.; Festa, G.; Francois-Holden, C.; Monelli, D.; Uchide, T.; Zahradnik, J.

2007-12-01

371

One-dimensional kinematic model of preferred orientation development

NASA Astrophysics Data System (ADS)

The one-dimensional model to analyse the kinematics of crystallographic preferred orientation of Ribe (1989)is presented and developed further. It is argued that this approach can be applied to rotational deformations where the predominant deformation mechanism is grain boundary sliding. Two contrasting situations are distinguished. The first is where lattice rotations of opposing sense occur and there are orientations for which the rotation rate is zero. In this case a continually intensifying preferred orientation at an orientation with zero rotation rate will result. The second situation is where the rotation of the lattice is in the same sense for all orientations. Initially maxima develop in the orientation of greatest negative divergence in the lattice rotation rate function. A steady-state preferred orientation profile is possible which is the normalised inverse of the function describing lattice rotation rate vs. orientation and the maxima are at the orientations for which the lattice rotation rate is a minimum. The intensity of the preferred orientation is a function of the ratio of the greatest to least lattice rotation rates. The results are applied to a natural mylonite preferred orientation which consists of a c axis maximum in the mylonitic foliation perpendicular to the stretching lineation. It is argued that the crystal lattices rotate about a stably oriented c axis and the profile through the orientation distribution describing the probability of finding particular orientations differing by a rotation about c is inverted to give an estimate of the lattice rotation rate profile. It is found that the lattice rotates slowest when the second-order prism direction a is aligned parallel to the foliation normal and fastest when a is aligned sub-parallel to the stretching lineation.

Casey, Martin; McGrew, Allen J.

1999-03-01

372

A timewise kinematic method for satellite gradiometry: GOCE simulations

NASA Astrophysics Data System (ADS)

We have defined new algorithms for the data processing of a satellite geodesy mission with gradiometer (such as the next European mission GOCE) to extract the information on the gravity field coefficients with a realistic estimate of their accuracy. The large scale data processing can be managed by a multistage decomposition. First the spacecraft position is determined, i.e., a kinematic method is normally used. Second we use a new method to perform the necessary digital calibration of the gradiometer. Third we use a multiarc approach to separately solve for the global gravity field parameters. Fourth we use an approximate resonant decomposition, that is we partition in a new way the harmonic coefficients of the gravity field. Thus the normal system is reduced to blocks of manageable size without neglecting significant correlations. Still the normal system is badly conditioned because of the polar gaps in the spatial distribution of the data. We have shown that the principal components of the uncertainty correspond to harmonic anomalies with very small signal in the region where GOCE is flying; these uncertainties cannot be removed by any data processing method. This allows a complete simulation of the GOCE mission with affordable computer resources. We show that it is possible to solve for the harmonic coefficients up to degree 200 220 with signal to error ratio ?1, taking into account systematic measurement errors. Errors in the spacecraft orbit, as expected from state of the art satellite navigation, do not degrade the solution. Gradiometer calibration is the main problem. By including a systematic error model, we have shown that the results are sensitive to spurious gradiometer signals at frequencies close to the lower limit of the measurement band. If these spurious effects grow as the inverse of the frequency, then the actual error is larger than the formal error only by a factor ?2, that is the results are not compromised.

Milani, Andrea; Rossi, Alessandro; Villani, Daniela

2005-10-01

373

Modular theory of inverse systems

NASA Technical Reports Server (NTRS)

The relationship between multivariable zeros and inverse systems was explored. A definition of zero module is given in such a way that it is basis independent. The existence of essential right and left inverses were established. The way in which the abstract zero module captured previous definitions of multivariable zeros is explained and examples are presented.

1979-01-01

374

Temperature inversion in China seas

Temperature inversion was reported as a common phenomenon in the areas near the southeastern Chinese coast (region A), west and south of the Korean Peninsula (region B), and north and east of the Shandong Peninsula (region C) during October–May in the present study, based on hydrographic data archived from 1930 through 2001 (319,029 profiles). The inversion was found to be

Jiajia Hao; Yongli Chen; Fan Wang

2010-01-01

375

Early-type galaxies kinematics (Rampazzo+ 1998)

NASA Astrophysics Data System (ADS)

We present data on the stellar kinematics of the brightest ellipticals in HCG 62, HCG 68, NGC 2300 groups. Moreover, we report on ASCA GIS as well as optical observations of the early-type member of the pair K 416 (NGC 5480/5481) similar, in many respects, to the dominant pair in the NGC 2300 group. The kinematics of HCG 62a/b and HCG 68a/b indicate that they are not interacting pairs. HCG 62a is instead possibly interacting with HCG 62c, as suggested by their morphology (see Mendes de Oliveira and Hickson 1994), In contrast to the results for the NGC 2300/2276 group, ASCA observations indicate a significant absence of hot gas in the K 416 system. Whether the NGC 2300 multiplet is viewed as a loose group or as a massive E+S pair, it is clear that similar morphological entities do not always show similar X-ray properties. Under the hypothesis that diffuse X-ray emission marks the group potential, we consider the possibility that K 416 is an unbound encounter. In this scenario, morphological distortions are indicative of the ongoing interaction, but are only circumstantially correlated with the physical reality of a pair/multiplet as a bound system. (1 data file).

Rampazzo, R.; Covino, S.; Trinchieri, G.; Reduzzi, L.

1998-01-01

376

Friction Stir Welding at MSFC: Kinematics

NASA Technical Reports Server (NTRS)

In 1991 The Welding Institute of the United Kingdom patented the Friction Stir Welding (FSW) process. In FSW a rotating pin-tool is inserted into a weld seam and literally stirs the faying surfaces together as it moves up the seam. By April 2000 the American Welding Society International Welding and Fabricating Exposition featured several exhibits of commercial FSW processes and the 81st Annual Convention devoted a technical session to the process. The FSW process is of interest to Marshall Space Flight Center (MSFC) as a means of avoiding hot-cracking problems presented by the 2195 aluminum-lithium alloy, which is the primary constituent of the Lightweight Space Shuttle External Tank. The process has been under development at MSFC for External Tank applications since the early 1990's. Early development of the FSW process proceeded by cut-and-try empirical methods. A substantial and complex body of data resulted. A theoretical model was wanted to deal with the complexity and reduce the data to concepts serviceable for process diagnostics, optimization, parameter selection, etc. A first step in understanding the FSW process is to determine the kinematics, i.e., the flow field in the metal in the vicinity of the pin-tool. Given the kinematics, the dynamics, i.e., the forces, can be targeted. Given a completed model of the FSW process, attempts at rational design of tools and selection of process parameters can be made.

Nunes, A. C., Jr.

2001-01-01

377

Kinematic GPS Profiles to monitor surface deformation

NASA Astrophysics Data System (ADS)

GPS kinematic measurement consists in placing a GPS rover receiver that registers its position on a moving vehicule with a high frequency. The frequency of the data acquisition is chosen according to the number of points and the precision needed to characterize the rover trajectory. The position of the rover receiver can be determined with respect to another GPS reference station with a precision of a few centimeters. Consequently different kinematic profiles on trajectories can be realized in different contexts (volcano slopes, active faults,...). We first studied the correlation between different profiles on the same trajectory in the absense of any particular event. Then different individual profiles are interpolated and a single profiles is generated which we refer to as "tube". We also studied and analyzed the impact of different parameters such as the baseline length, the atmospheric errors and the number of individual profiles on the precision of the obtained tube. We present results of experimentations that were performed in Chili, Reunion Island and Greece and we show how the results can be influenced by the baselines lengths and topographies. In case of event (Earthquakes, volcanoes eruptions, landslides,...) this technique can be used to assess the amplitude of ground deformation. We estimate the thresholds (in term of amplitude and spatial extension) of detectable signals.

Charara, R.; Vigny, C.; Briole, P.

2008-12-01

378

Kinematics of signature writing in healthy aging.

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

379

Warm gas kinematics in shell galaxies

NASA Astrophysics Data System (ADS)

Shells are interpreted as debris from interaction/acquisition episodes that occur in a galaxy. We present a study of the warm (T~ 104 K) gas component in a sample of five shell galaxies belonging to the Malin & Carter compilation. H? observations have been obtained at the ESO 3.6-m telescope equipped with a CIGALE scanning Fabry-Perot interferometer coupled with a new IPCS camera. Most of our sample galaxies show disturbed/irregular gaseous velocity fields. The gas distribution in NGC 7070A and 7135 shows elongated, asymmetric structure relative to the stellar body. The continuum and line maps for ESO 2400100 show a double nucleus. The nuclei are slightly off-centre with respect to the barycentre of the pair, a deformation that cannot arise from projection effects and that suggests a strong on-going tidal interaction. Kinematics of the stellar and gas component derived for NGC 1553 are similar, although the gas component shows evidence for non-circular motion. In most of our objects the gas and the stellar kinematics appear decoupled, but no rings of gas nor diffuse gas shells are detected. If shell galaxies form through an acquisition/merging event, the general hypothesis according to which the gas in Es is accreted from outside the galaxy is further supported by these data. We speculate concerning shell galaxy evolution using additional information coming from studies of line-strength indices.

Rampazzo, R.; Plana, H.; Longhetti, M.; Amram, P.; Boulesteix, J.; Gach, J.-L.; Hernandez, O.

2003-08-01

380

Nuclear Rings in Galaxies - A Kinematic Perspective

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

381

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

382

NASA Technical Reports Server (NTRS)

The application of convex profile inversion (CPI) to the interpretation of asteroid lightcurves is discussed. This technique investigates the problem of extracting information about an asteroid's shape from its lightcurve. Whenever four ideal conditions are met, P is an estimator for the asteroids mean cross section C, a convex set defined as the average of all cross sections C(Z) cut by planes a distance z above the asteroids equatorial plane. C is therefore a 2-D average of the asteroids 3-D shape. The method is tested by inverting lightcurves generated analytically for geometrically scattered ellipsoids (GSE's) with semiaxes a or = B or = C. Using a defined 'distance measure' to quantify the difference between any two profiles, the deviation of P from C for GSE's as a function of lightcurve noise level, rotation phase sampling interval delta theta, and departure from ideal conditions is calibrated. The distance between P and a circle provides a gauge of the asteroid's nonsphericity and incorporates all the information contained in the lightcurve.

Ostrow, S. J.

1984-01-01

383

We have implemented the Jacobian-free Newton-Krylov (JFNK) method for solving the rst-order ice sheet momentum equation in order to improve the numerical performance of the Community Ice Sheet Model (CISM), the land ice component of the Community Earth System Model (CESM). Our JFNK implementation is based on signicant re-use of existing code. For example, our physics-based preconditioner uses the original Picard linear solver in CISM. For several test cases spanning a range of geometries and boundary conditions, our JFNK implementation is 1.84-3.62 times more efficient than the standard Picard solver in CISM. Importantly, this computational gain of JFNK over the Picard solver increases when rening the grid. Global convergence of the JFNK solver has been signicantly improved by rescaling the equation for the basal boundary condition and through the use of an inexact Newton method. While a diverse set of test cases show that our JFNK implementation is usually robust, for some problems it may fail to converge with increasing resolution (as does the Picard solver). Globalization through parameter continuation did not remedy this problem and future work to improve robustness will explore a combination of Picard and JFNK and the use of homotopy methods.

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

2011-01-01

384

NASA Astrophysics Data System (ADS)

Stylolites are localized dissolution seams that can be found in a variety of rocks, and can form due to sediment compaction or tectonic forces. Dissolution of the host-rock next to the stylolite is a function of the applied stress on the stylolite plane. Stylolite teeth indicate the direction of the main compressive stress. Recent advances have shown that the stylolite roughness also shows a stress scaling relation that can be used to calculate magnitudes of stress. Elastic and surface energies produce a different roughness, and the transition between the two is stress dependent and can be quantified. In order to measure the roughness a two or three-dimensional section of a stylolite plane is taken and transferred to a one-dimensional function. The cross-over in the roughness is then picked with the help of an FFT plot. Using this method the burial depth of sedimentary stylolites can be determined. Moreover, tectonic stylolites can be used to determine the full three-dimensional stress tensor if the paleodepth of the tectonic stylolite is known. Stylolites can also be used to find fault offsets and to understand when these faults were active and how the paleotopography looked like at the time the stylolites grew. However, uncertainties remain since Youngs Modulus, Poisson Ratio and surface energy may vary in rocks. In addition, the stylolites record only a snapshot in time, probably the moment when they closed and stopped dissolving. We show examples of the use of stress inversion for stylolite formation conditions in different tectonic settings, and discuss the potential of the method.

Koehn, Daniel; Toussaint, Renaud; Ebner, Marcus; Gomez-Rivas, Enrique; Bons, Paul; Rood, Daisy

2014-05-01

385

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

386

NASA Astrophysics Data System (ADS)

This work presents a traveltime inversion method developed specially for imaging detailed subsurface features in the case of heterogeneous soils. The algorithm considers the initial SIRT algorithm proposed by Grandjean and Sage (2004) based on the use of Fresnel wavepaths and a probabilistic reconstruction approach. The method is improved by using a Quasi-Newton method, more robust than SIRT. It is demonstrated that the Jacobian matrix is approximated by the Fresnel weights, without introducing too large uncertainties. In addition to its robustness, this inversion algorithm proposes a regularization strategy based on the physics of wave propagation in soil. This allows to overcome the use of numerical regularization operators, always difficult to parameterize, and to remove the subjectivity of the user in the inversion result. Moreover, as the width of Fresnel volume is related to the frequency, an increase of frequency (and therefore a decrease of Fresnel wavepaths width) is introduced for each step in order to cover the entire finite bandwidth of the source signal. The inversion is thus controlled by large variations of velocities in the first steps and more and more detailed heterogeneities of the soil in the following steps. This technique is applied to a real dataset acquired at the Super-Sauze landslide (French Alps) and allows to highlight the presence of a deep water supply interpreted as a preferential flow path within the landslide.

Gance, J.; Samyn, K.; Grandjean, G.; Malet, J.-P.

2012-04-01

387

NASA Astrophysics Data System (ADS)

The Border Ranges Fault System (BRFS) bounds the Cook Inlet and Susitna Basins, and is an important petroleum province within south-central Alaska. A primary goal of our research is to test several plausible models of structure along the BRFS using a novel three-dimensional inversion technique utilizing gravity data, constrained with other geophysical, borehole and surface geological information. This research involves the development of 3D inversion modeling software using C++ Builder from Embarcadero's XE2 Suite. The novel inversion approach directly models known geology with a priori uncertainties assigned to the geologic model to allow researchers to compare alternative interpretations. This technique was developed to evaluate three-dimensional structure in regions of complex and poorly known geology. Our software computes the density solution of a geologic structure by utilizing its location within the gravity field as well as the gridded surface files of known topography and subsurface units. The total gravitational effect of each body is calculated with a series of semi-infinite vertical line elements which improves the computational efficiency of computing forward models of structures with extremely complex geometry. The inversion algorithm considers a priori geophysical constraints and uncertainties due to gravity measurements, surface file inconsistencies, and forward calculations in the model solution. In addition, a Kalman-based filtering estimator is used to minimize our observation and processing noise. The estimator allows the a posteriori covariance matrix to avoid its dependence on the non-singularity of the Jacobian (model) matrix.

Cardenas, Rolando

388

Kinematic analysis of over-determinate biomechanical systems

In this paper, we introduce a new general method for kinematic analysis of rigid multi body systems subject to holonomic constraints. The method extends the standard analysis of kinematically determinate rigid multi body systems to the over-determinate case. This is accomplished by introducing a constrained optimisation problem with the objective function given as a function of the set of system

M. S. Andersen; M. Damsgaard; J. Rasmussen

2009-01-01

389

Kinematic Disturbances in Rotation Curves among 89 Virgo Galaxies

For 89 (mostly) spirals in the Virgo cluster, we have obtained optical long-slit spectra of the ionized gas. We find: (1) 50% of the Virgo galaxies we observed have regular rotation patterns; 50% exhibit kinematic disturbances ranging from mild to major. Velocity complexities are consistent with those resulting from tidal encounters or accretion. Since kinematic disturbances will to fade within

V. C. Rubin; A. H. Waterman; J. D. P. Kenney

1999-01-01

390

Constrained multi-objective trajectory planning of parallel kinematic machines

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

391

Mobile robot trajectory planning with dynamic and kinematic constraints

This paper presents methods for planning mobile robot trajectories by considering the kinematic and dynamic constraints on the vehicle motion. The resulting path is smooth and quasilinear in curvature variations. The maximum value of the curvature can be assured to be smaller than the value given by the constraints. Furthermore, speeds along the path are planned subject to the kinematic

V. Muiiozt; A. Ollerott; M. Prado; A. Simon

1994-01-01

392

Hand-hold location and trunk kinematics during box handling.

Trunk kinematics variables have been shown to be related to low back injury risk during lifting tasks and it was hypothesised that changes in hand-hold positions could influence trunk kinematics and thereby risk. Fourteen subjects lifted a 5 or 10 kg box using four different hand placement locations (two symmetric and two asymmetric) while their trunk kinematics (position, velocity and acceleration in the sagittal, coronal and transverse planes) were captured using the lumbar motion monitor (LMM). These kinematics data were then used to calculate the probability of high risk group membership (PHRGM) as defined in the LMM risk assessment model. The results showed significant effects of hand placement on trunk kinematics, resulting in significant changes in the PHRGM variable ranging from a low of 20% in a the symmetric low load condition to a high of 38% under the asymmetric, 10 kg condition. STATEMENT OF RELEVANCE: Manual materials handlers use a variety of hand-hold positions on boxes during lifting. Where a lifter grabs the box can influence the trunk kinematics during the lifting task and these kinematics have been shown to provide some insight into risk of low back injury. This study documents the trunk postures and kinematics as a function of hand-hold position. PMID:20658397

Haddad, Omid; Mirka, Gary A

2010-08-01

393

Effects of Vocal Training on Respiratory Kinematics during Singing Tasks

This longitudinal study determined the effects of vocal training (VT) on respiratory kinematics and muscle activity during singing tasks. Four voice students, 3 females and 1 male, were recorded during singing tasks once a semester for 3 consecutive semesters. Respiratory kinematic measures included lung volume, rib cage (RCE) and abdominal excursions (ABE). Surface electromyographic measures included burst duration (BD) and

Ana P. Mendes; W. S. Brown; Christine Sapienza; Howard B. Rothman

2006-01-01

394

Hybrid multi-objective motion planning of Parallel Kinematic Machines

In this paper we consider the problem of multi-objective trajectory planning to Parallel Kinematic Machines (PKMs). A two stage system is developed. In a first stage is an offline planning based on robot kinematics and dynamics, including actuators, is performed to generate a large dataset of trajectories, these trajectory cover mostly of the robot workspace and minimize time and energy,

A. Khoukhi

2010-01-01

395

Robotic fish motion planning under inherent kinematic constraints

This paper presents a real-time motion planning method for biomimetic robotic fish with kinematic constraints. Based on successfully developing a robotic fish prototype, we step further to study navigation problem of the robotic fish in dynamic water environments. Considering the inherent kinematic constraints of the robotic fish, a new control law is proposed to stabilize the robotic fish on a

Dandan Zhang; Junzhi Yu; Guangming Xie

2006-01-01

396

Kinematics Modeling and Experiments of Pectoral Oscillation Propulsion Robotic Fish

A robotic fish driven by oscillating fins, “Cownose Ray-I”, is developed, which is in dorsoventrally flattened shape without a tail. The robotic fish is composed of a body and two lateral fins. A three-factor kinematic model is established and used in the design of a mechanism. By controlling the three kinematic parameters, the robotic fish can accelerate and maneuver. Forward

Shao-bo Yang; Jing Qiu; Xiao-yun Han

2009-01-01

397

Kinematic modeling of a bio-inspired robotic fish

This paper proposes a kinematic modeling method for a bio-inspired robotic fish based on single joint. Lagrangian function of freely swimming robotic fish is built based on a simplified geometric model. In order to build the kinematic model, the fluid force acting on the robotic fish is divided into three parts: the pressure on links, the approach stream pressure and

Chao Zhou; Min Tan; Zhiqiang Cao; Shuo Wang; Douglas Creighton; Nong Gu; Saeid Nahavandi

2008-01-01

398

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

399

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

400

Uncertainty quantification in kinematic wave models

We developed a probabilistic approach to quantify parametric uncertainty in first-order hyperbolic conservation laws (kinematic wave equations). The approach relies on the derivation of a deterministic equation for the cumulative density function (CDF) of the system state, in which probabilistic descriptions (probability density functions or PDFs) of the system parameters and/or initial and boundary conditions serve as inputs. In contrast to PDF equations, which are often used in other contexts, CDF equations allow for straightforward and unambiguous determination of boundary conditions with respect to sample variables.The accuracy and robustness of solutions of the CDF equation for one such system, the Saint-Venant equations of river flows, were investigated via comparison with Monte Carlo simulations.

Wang, Peng; Tartakovsky, Daniel M.

2012-10-01

401

Growth rate degeneracies in kinematic dynamos.

We consider the classical problem of kinematic dynamo action in simple steady flows. Due to the adjointness of the induction operator, we show that the growth rate of the dynamo will be exactly the same for two types of magnetic boundary conditions: the magnetic field can be normal (infinite magnetic permeability, also called pseudovacuum) or tangent (perfect electrical conductor) to the boundaries of the domain. These boundary conditions correspond to well-defined physical limits often used in numerical models and relevant to laboratory experiments. The only constraint is for the velocity field u to be reversible, meaning there exists a transformation changing u into -u. We illustrate this surprising property using S_{2}T_{2} type of flows in spherical geometry inspired by [Dudley and James, Proc. R. Soc. London A 425, 407 (1989)]. Using both types of boundary conditions, it is shown that the growth rates of the dynamos are identical, although the corresponding magnetic eigenmodes are drastically different. PMID:24125205

Favier, B; Proctor, M R E

2013-09-01

402

Testing student interpretation of kinematics graphs

NSDL National Science Digital Library

Recent work has uncovered a consistent set of student difficulties with graphs of position, velocity, and acceleration versus time. These include misinterpreting graphs as pictures, slope/height confusion, problems finding the slopes of lines not passing through the origin, and the inability to interpret the meaning of the area under various graph curves. For this particular study, data from 895 students at the high school and college level was collected and analyzed. The test used to collect the data is included at the end of the article and should prove useful for other researchers studying kinematics learning as well as instructors teaching the material. The process of developing and analyzing the test is fully documented and is suggested as a model for similar assessment projects.

Beichner, Robert J.

2005-10-11

403

Kinematic tests of exotic flat cosmological models

NASA Technical Reports Server (NTRS)

Theoretical prejudice and inflationary models of the very early universe strongly favor the flat, Einstein-de Sitter model of the universe. At present the observational data conflict with this prejudice. This conflict can be resolved by considering flat models of the universe which posses a smooth component of energy density. The kinematics of such models, where the smooth component is relativistic particles, a cosmological term, a network of light strings, or fast-moving, light strings is studied in detail. The observational tests which can be used to discriminate between these models are also discussed. These tests include the magnitude-redshift, lookback time-redshift, angular size-redshift, and comoving volume-redshift diagrams and the growth of density fluctuations.

Charlton, Jane C.; Turner, Michael S.

1987-01-01

404

Unraveling L_{n,k}: Grassmannian Kinematics

It was recently proposed that the leading singularities of the S-Matrix of N = 4 super Yang-Mills theory arise as the residues of a contour integral over a Grassmannian manifold, with space-time locality encoded through residue theorems generalizing Cauchy's theorem to more than one variable. We provide a method to identify the residue corresponding to any leading singularity, and we carry this out explicitly for all leading singularities at tree level and one-loop. We also give several examples at higher loops, including all generic two-loop leading singularities and an interesting four-loop object. As an example we consider a 12-pt N{sup 4}MHV leading singularity at two loops that has a kinematic structure involving double square roots. Our analysis results in a simple picture for how the topological structure of loop graphs is reflected in various substructures within the Grassmannian.

Kaplan, Jared; /SLAC

2010-02-15

405

Adjustable link for kinematic mounting systems

An adjustable link for kinematic mounting systems is disclosed. The adjustable link is a low-cost, passive device that provides backlash-free adjustment along its single constraint direction and flexural freedom in all other directions. The adjustable link comprises two spheres, two sockets in which the spheres are adjustable retain, and a connection link threadly connected at each end to the spheres, to provide a single direction of restraint and to adjust the length or distance between the sockets. Six such adjustable links provide for six degrees of freedom for mounting an instrument on a support. The adjustable link has applications in any machine or instrument requiring precision adjustment in six degrees of freedom, isolation from deformations of the supporting platform, and/or additional structural damping. The damping is accomplished by using a hollow connection link that contains an inner rod and a viscoelastic separation layer between the two. 3 figs.

Hale, L.C.

1997-07-01

406

Wilson loops @ 3-loops in special kinematics

NASA Astrophysics Data System (ADS)

We obtain a compact expression for the octagon MHV amplitude/Wilson loop at 3 loops in planar mathcal{N} = {4} SYM and in special 2d kinematics in terms of 7 unfixed coefficients. We do this by making use of the cyclic and parity symmetry of the amplitude/Wilson loop and its behaviour in the soft/collinear limits as well as in the leading term in the expansion away from this limit. We also make a natural and quite general assumption about the functional form of the result, namely that it should consist of weight 6 polylogarithms whose symbol consists of basic cross-ratios only (and not functions thereof). We also describe the uplift of this result to 10 points.

Heslop, Paul; Khoze, Valentin V.

2011-11-01

407

Kinematics of trajectories in classical mechanics

NASA Astrophysics Data System (ADS)

In this paper, we show how the study of kinematics of a family of trajectories of a classical mechanical system may be unified within the framework of analysis of geodesic flows in Riemannian geometry and relativity. After setting up the general formalism, we explore it through studies on various one- and two-dimensional systems. Quantities like expansion, shear and rotation (ESR), which are more familiar to the relativist, now reappear while studying such families of trajectories in configuration space, in very simple mechanical systems. The convergence/divergence of a family of trajectories during the course of time evolution, the shear and twist of the area enclosing the family, and the focusing/defocusing of the trajectories within a finite time are investigated analytically for these systems. The understanding of the configuration space developed through such investigations is elaborated upon, and possible future avenues are pointed out.

Shaikh, Rajibul; Kar, Sayan; DasGupta, Anirvan

2014-05-01

408

A kinematic model of southern California

NASA Technical Reports Server (NTRS)

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.

Weldon, R.; Humphreys, E.

1986-01-01

409

A kinematic model of a ducted flame

NASA Astrophysics Data System (ADS)

A premixed ducted flame, burning in the wake of a bluff-body flame-holder, is considered. For such a flame, interaction between acoustic waves and unsteady combustion can lead to self-excited oscillations. The concept of a time-invariant turbulent flame speed is used to develop a kinematic model of the response of the flame to flow disturbances. Variations in the oncoming flow velocity at the flame-holder drive perturbations in the flame initiation surface and hence in the instantaneous rate of heat release. For linear fluctuations, the transfer function between heat release and velocity can be determined analytically from the model and is in good agreement with experiment across a wide frequency range. For nonlinear fluctuations, the model reproduces the flame surface distortions seen in schlieren films.

Dowling, A. P.

1999-09-01

410

Galaxy simulations: Kinematics and mock observations

NASA Astrophysics Data System (ADS)

There are six topics to my thesis, which are: (1) slow rotator production in varied simulation schemes and kinematically decoupled cores and twists in those simulations, (2) the change in number of clumps in radiation pressure and no-radiation pressure simulations, (3) Sunrise experiments and failures including UVJ color-color dust experiments and UVbeta slopes, (4) the Sunrise image pipeline and algorithms. Cosmological simulations of have typically produced too many stars at early times. We find that the additional radiation pressure (RP) feedback suppresses star formation globally by a factor of ~ 3. Despite this reduction, the simulation still overproduces stars by a factor of ~ 2 with respect to the predictions provided by abundance matching methods. In simulations with RP the number of clumps falls dramatically. However, only clumps with masses Mclump/Mdisk ? 8% are impacted by the inclusion of RP, and clump counts above this range are comparable. Above this mass, the difference between and RP and no-RP contrast ratios diminishes. If we restrict our selection to galaxies hosting at least a single clump above this mass range then clump numbers, contrast ratios, survival fractions and total clump masses show little discrepancy between RP and no-RP simulations. By creating mock Hubble Space Telescope observations we find that the number of clumps is slightly reduced in simulations with RP. We demonstrate that clumps found in any single gas, stellar, or mock observation image are not necessarily clumps found in another map, and that there are few clumps common to multiple maps. New kinematic observations from ATLAS3D have highlighted the need to understand the evolutionary mechanism leading to a spectrum of fast-rotator and slow-rotators in early-type galaxies. We address the formation of slow and fast rotators through a series of controlled, comprehensive hydrodynamic simulations sampling idealized galaxy merger formation scenarios constructed from model spiral galaxies. We recreate minor and major binary mergers, binary merger trees with multiple progenitors, and multiple sequential mergers. Within each of these categories of formation history, we correlate progenitor gas fraction, mass ratio, orbital pericenter, orbital ellipticity, spin, and kinematically decoupled cores with remnant kinematic properties. We find that binary mergers nearly always form fast rotators, but slow rotators can be formed from zero initial angular momentum configurations and gas-poor mergers. Remnants of binary merger trees are triaxial slow rotators. Sequential mergers form round slow rotators that most resemble the ATLAS3D rotators. We investigate the failure of ART and Sunrise simulation to reproduce the observed distribution of galaxies in the UVJ color-color diagram. No simulated galaxies achieve a color with V-J >1.0 while still being in the blue sequence. I systematically study the underlying sub grid models present in Sunrise to diagnose the source of the discrepancy. The experiments were largely unsuccessful in directly isolating the root of the J-band excess attenuation; however, they are instructive and can guide the intuition in terms of understanding the interplay of stellar emission and dust. These experiments were aimed at understanding the role of the underlying sub grid dust and radiation models, varying the dust geometry, and performing numerical studies of the radiation transfer calculation. Finally, I detail the data pipeline responsible for the creation of galaxy mock observations. The pipeline can be broken into the ART simulation raw data, the dark matter merger tree backbone, the format translation using yt, simulation the radiation transfer in Sunrise, and post-processed image treatments resulting. At every step, I detail the execution of the algorithms, the format of the data, and useful scripts for straightforward analysis.

Moody, Christopher E.

411

Modelling the gas kinematics in disk galaxies

NASA Astrophysics Data System (ADS)

Over the last few years, evidence that nearby spiral galaxies are surrounded by massive halos of cold gas has been accumulating. This extra-planar cold gas, rotating more slowly than the disk gas, is observed in galaxies with a range of different properties (such as mass and star formation rate, SFR) and it appears analogous to the Intermediate and High Velocity Clouds of the Milky Way. Models for the origin of extra-planar gas have been proposed taking into account the effects of supernova feedback (galactic fountain), cooling flow accretion and hydrostatic equilibrium. Several techniques have been used from analytical treatments and ballistic orbit integration to hydrodynamical simulations. I present a new model where a galactic fountain sweeps up ambient medium as it travels through the halo. This seems to give the best results in reproducing the kinematics of the extra-planar gas and it implies a gas accretion rate of the order of the SFR of the host galaxy.

Fraternali, F.

2012-09-01

412

Mg II Absorbing Galaxies: Morphologies and Kinematics

NASA Astrophysics Data System (ADS)

In this contribution, we review our current knowledge of the properties of galaxies, and their extended halos, selected by Mg II absorption in the spectra of background quasars. We then describe recent efforts to quantify the morphologies and orientations of galaxies and explore how these relate to the gas kinematics. In a sample of 26 galaxies, we find no clear connection between the orientation of the quasar line of sight through the galaxy and the velocity spread of the gas. However, it appears that the quantity of gas "stirred up" in the halo may be correlated to asymmetry in the galaxy morphology. Since the galaxies have fairly normal morphologies, this connection may suggest that galaxies with extended halos experienced an interaction or merging event a few dynamical times prior to the epoch of observation.

Churchill, C.; Steidel, C.; Kacprzak, G.

2005-06-01

413

Relativistic kinematics for motion faster than light

NASA Technical Reports Server (NTRS)

The use of conformal coordinates in relativistic kinematics is illustrated and a simple extension of the theory of motions faster than light is provided. An object traveling at a speed greater than light discloses its presence by appearing suddenly at a point, splitting into two apparent objects which then recede from each other at sublight velocities. According to the present theory motion at speeds faster than light would not benefit a space traveler, since the twin paradox becomes inverted at such speeds. In Einstein's theory travel at the velocity of light in an intertial system is equivalent to infinite velocity for the traveler. In the present theory the converse is also true; travel at infinite velocity is equivalent to the velocity of light for the traveler.

Jones, R. T.

1982-01-01

414

Adjustable link for kinematic mounting systems

An adjustable link for kinematic mounting systems. The adjustable link is a low-cost, passive device that provides backlash-free adjustment along its single constraint direction and flexural freedom in all other directions. The adjustable link comprises two spheres, two sockets in which the spheres are adjustable retain, and a connection link threadly connected at each end to the spheres, to provide a single direction of restraint and to adjust the length or distance between the sockets. Six such adjustable links provide for six degrees of freedom for mounting an instrument on a support. The adjustable link has applications in any machine or instrument requiring precision adjustment in six degrees of freedom, isolation from deformations of the supporting platform, and/or additional structural damping. The damping is accomplished by using a hollow connection link that contains an inner rod and a viscoelastic separation layer between the two.

Hale, Layton C. (Livermore, CA)

1997-01-01

415

Global and regional kinematics from SLR stations

NASA Technical Reports Server (NTRS)

The stations of the Global Laser Tracking Network have significantly contributed to the measurement of plate kinematics. The expanding network of progressively improved instruments clearly demonstrates the systems' centimeter positioning accuracy. Several satellite laser ranging (SLR) analysis groups have adopted techniques to distill geodynamic information from the Lageos-1 satellite observations using orbital arc lengths from an hour to a decade. SLR observations now provide the scale for the International Terrestrial Reference System and help to define the Earth's polar motion in this system. Agreement between positions separately determined with SLR, VLBI and GPS systems has been established at the level of a few centimeters in position and a few millimeters per year in horizontal velocity.

Dunn, Peter J.

1994-01-01

416

Numerical analysis of kinematic soil-pile interaction

In the present study, the response of singles pile to kinematic seismic loading is investigated using the computer program SAP2000. The objectives of the study are: (1) to develop a numerical model that can realistically simulate kinematic soil-structure interaction for piles accounting for discontinuity conditions at the pile-soil interface, energy dissipation and wave propagation; (2) to use the model for evaluating kinematic interaction effects on pile response as function of input ground motion; and (3) to present a case study in which theoretical predictions are compared with results obtained from other formulations. To evaluate the effects of kinematic loading, the responses of both the free-field soil (with no piles) and the pile were compared. Time history and static pushover analyses were conducted to estimate the displacement and kinematic pile bending under seismic loadings.

Castelli, Francesco; Maugeri, Michele [Department of Civil and Environmental Engineering, University of Catania, Viale Andrea Doria no. 6, 95125, Catania (Italy); Mylonakis, George [Department of Civil Engineering, University of Patras, Rio GR-26500, Patras (Greece)

2008-07-08

417

Kinetic and kinematic adaptation to anisotropic load.

Different investigators have proposed that multi-joint arm movements are planned with respect to either the path of the hand or the forces and torques acting about the moving joints. In this experiment, we examined the kinematic and kinetic response of the motor system when a load was applied to the forearm, which reduced the natural anisotropy of the arm. We asked two questions: (1) when the movement path changes upon the introduction of the novel load, do muscle torques at the shoulder and elbow remain the same as they were before the load was applied? and (2) when the path is restored partially as the novel load is learned, do changes in muscle torque occur preferentially at one or the other joint? Participants performed rapid arm movements to a target with and without the novel load attached to their arm. Changes in hand path and muscle torque profiles were examined immediately after the application of the load and again following 30 practice trials. The introduction of the load increased the curvature of hand paths for each participant and resulted in changes in the magnitude and time course of muscle torque at both joints, although to a greater extent at the shoulder. After practice with the load, hand paths and elbow muscle torques resembled those produced with no load. Muscle torques produced at the shoulder, however, did not return to pre-load patterns. These observations provide support for the idea that movements are initiated by planned muscle torques and that as the movement proceeds muscle torques are regulated in order to produce hand paths that conform approximately to a kinematic plan. PMID:18726588

Shemmell, Jonathan; Corcos, Daniel M; Hasan, Ziaul

2009-01-01

418

Kinematics of Visually-Guided Eye Movements

One of the hallmarks of an eye movement that follows Listing’s law is the half-angle rule that says that the angular velocity of the eye tilts by half the angle of eccentricity of the line of sight relative to primary eye position. Since all visually-guided eye movements in the regime of far viewing follow Listing’s law (with the head still and upright), the question about its origin is of considerable importance. Here, we provide theoretical and experimental evidence that Listing’s law results from a unique motor strategy that allows minimizing ocular torsion while smoothly tracking objects of interest along any path in visual space. The strategy consists in compounding conventional ocular rotations in meridian planes, that is in horizontal, vertical and oblique directions (which are all torsion-free) with small linear displacements of the eye in the frontal plane. Such compound rotation-displacements of the eye can explain the kinematic paradox that the fixation point may rotate in one plane while the eye rotates in other planes. Its unique signature is the half-angle law in the position domain, which means that the rotation plane of the eye tilts by half-the angle of gaze eccentricity. We show that this law does not readily generalize to the velocity domain of visually-guided eye movements because the angular eye velocity is the sum of two terms, one associated with rotations in meridian planes and one associated with displacements of the eye in the frontal plane. While the first term does not depend on eye position the second term does depend on eye position. We show that compounded rotation - displacements perfectly predict the average smooth kinematics of the eye during steady- state pursuit in both the position and velocity domain.

Hess, Bernhard J. M.; Thomassen, Jakob S.

2014-01-01

419

Inversion layer MOS solar cells

NASA Technical Reports Server (NTRS)

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

Ho, Fat Duen

1986-01-01

420

Discrete Inverse Scattering Problems. II.

National Technical Information Service (NTIS)

A discrete version of the inverse scattering problem of the Schrodinger equation with a potential is discussed. The approach is via the Marchenko equation. Interest is primarily pedagogical. All steps are elementary and relatively obvious. Passage to the ...

K. M. Case

1973-01-01

421

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

422

Inverse Compensation for Ferromagnetic Hysteresis.

National Technical Information Service (NTIS)

This paper addresses the validation of an energy-based inverse compensator for hysteresis in ferromagnetic transducers. At moderate to high drive levels such transducers exhibit significant constitutive non-linearities and hysteresis due to domain mechani...

R. C. Smith R. Zrostlik

1999-01-01

423

Geophysical Inversion Tutorials and Workflows

NSDL National Science Digital Library

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

2011-07-01

424

Computation of inverse magnetic cascades

NASA Technical Reports Server (NTRS)

Inverse cascades of magnetic quantities for turbulent incompressible magnetohydrodynamics are reviewed, for two and three dimensions. The theory is extended to the Strauss equations, a description intermediate between two and three dimensions appropriate to Tokamak magnetofluids. Consideration of the absolute equilibrium Gibbs ensemble for the system leads to a prediction of an inverse cascade of magnetic helicity, which may manifest itself as a major disruption. An agenda for computational investigation of this conjecture is proposed.

Montgomery, D.

1981-01-01

425

Design, analysis and testing of a parallel-kinematic high-bandwidth XY nanopositioning stage.

This paper presents the design, analysis, and testing of a parallel-kinematic high-bandwidth XY nanopositioning stage driven by piezoelectric stack actuators. The stage is designed with two kinematic chains. In each kinematic chain, the end-effector of the stage is connected to the base by two symmetrically distributed flexure modules, respectively. Each flexure module comprises a fixed-fixed beam and a parallelogram flexure serving as two orthogonal prismatic joints. With the purpose to achieve high resonance frequencies of the stage, a novel center-thickened beam which has large stiffness is proposed to act as the fixed-fixed beam. The center-thickened beam also contributes to reducing cross-coupling and restricting parasitic motion. To decouple the motion in two axes totally, a symmetric configuration is adopted for the parallelogram flexures. Based on the analytical models established in static and dynamic analysis, the dimensions of the stage are optimized in order to maximize the first resonance frequency. Then finite element analysis is utilized to validate the design and a prototype of the stage is fabricated for performance tests. According to the results of static and dynamic tests, the resonance frequencies of the developed stage are over 13.6 kHz and the workspace is 11.2 ?m × 11.6 ?m with the cross-coupling between two axes less than 0.52%. It is clearly demonstrated that the developed stage has high resonance frequencies, a relatively large travel range, and nearly decoupled performance between two axes. For high-speed tracking performance tests, an inversion-based feedforward controller is implemented for the stage to compensate for the positioning errors caused by mechanical vibration. The experimental results show that good tracking performance at high speed is achieved, which validates the effectiveness of the developed stage. PMID:24387472

Li, Chun-Xia; Gu, Guo-Ying; Yang, Mei-Ju; Zhu, Li-Min

2013-12-01