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Sample records for jacobian inverse kinematics

  1. Dynamically consistent Jacobian inverse for mobile manipulators

    NASA Astrophysics Data System (ADS)

    Ratajczak, Joanna; Tchoń, Krzysztof

    2016-06-01

    By analogy to the definition of the dynamically consistent Jacobian inverse for robotic manipulators, we have designed a dynamically consistent Jacobian inverse for mobile manipulators built of a non-holonomic mobile platform and a holonomic on-board manipulator. The endogenous configuration space approach has been exploited as a source of conceptual guidelines. The new inverse guarantees a decoupling of the motion in the operational space from the forces exerted in the endogenous configuration space and annihilated by the dual Jacobian inverse. A performance study of the new Jacobian inverse as a tool for motion planning is presented.

  2. JFKengine: A Jacobian and Forward Kinematics Generator

    SciTech Connect

    Fischer, K.N.

    2003-02-13

    During robot path planning and control the equations that describe the robot motions are determined and solved. Historically these expressions were derived analytically off-line. For robots that must adapt to their environment or perform a wide range of tasks, a way is needed to rapidly re-derive these expressions to take into account the robot kinematic changes, such as when a tool is added to the end-effector. The JFKengine software was developed to automatically produce the expressions representing the manipulator arm motion, including the manipulator arm Jacobian and the forward kinematic expressions. Its programming interface can be used in conjunction with robot simulation software or with robot control software. Thus, it helps to automate the process of configuration changes for serial robot manipulators. If the manipulator undergoes a geometric change, such as tool acquisition, then JFKengine can be invoked again from the control or simulation software, passing it parameters for the new arm configuration. This report describes the automated processes that are implemented by JFKengine to derive the kinematic equations and the programming interface by which it is invoked. Then it discusses the tree data structure that was chosen to store the expressions, followed by several examples of portions of expressions as represented in the tree. The C++ classes and their methods that implement the expression differentiation and evaluation operations are described. The algorithms used to construct the Jacobian and forward kinematic equations using these basic building blocks are then illustrated. The activity described in this report is part of a larger project entitled ''Multi-Optimization Criteria-Based Robot Behavioral Adaptability and Motion Planning'' that focuses on the development of a methodology for the generalized resolution of robot motion equations with time-varying configurations, constraints, and task objective criteria. A specific goal of this project is

  3. Visualization of redundancy resolution for kinematically redundant robots through the Jacobian null space

    NASA Technical Reports Server (NTRS)

    Chen, Yu-Che; Walker, Ian D.; Cheatham, John B., Jr.

    1992-01-01

    We present a unified formulation for the inverse kinematics of redundant arms, based on a special formulation of the null space of the Jacobian. By extending (appropriately re-scaling) previously used null space parameterizations, we obtain, in a unified fashion, the manipulability measure, the null space projector, and particular solutions for the joint velocities. We obtain the minimum norm pseudo-inverse solution as a projection from any particular solution, and the method provides an intuitive visualization of the self-motion. The result is a computationally efficient, consistent approach to computing redundant robot inverse kinematics.

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

    SciTech Connect

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

    1995-07-01

    A method for kinematically modeling a constrained rigid body mechanical system and a method for controlling such a system termed input relegation control (IRC) were applied to resolve the kinematic redundancy of a serial link manipulator moving in an open chain configuration in. A set of equations was introduced to define a new vector variable parameterizing the redundant degrees of freedom (DOF) as a linear function of the joint velocities. The new set was combined with the classical kinematic velocity model of manipulator and solved to yield a well specified solution for the joint velocities as a function of the Cartesian velocities of the end effector and of the redundant DOF variable. In the previous work a technique was proposed for selecting the matrix relating the redundant DOF variable to the joint velocities which resulted in it rows being orthogonal to the rows of the Jacobian matrix. The implications for such a selection were not discussed in. In Part 1 of this report a basis for the joint space is suggested which provides considerable insight into why picking the aforementioned matrix to be orthogonal to the Jacobian is advantageous. A second objective of Part 1 is to compare the IRC method to the Extended Jacobian method of Baillieul and Martin and other related methods.

  5. Challenges of Inversely Estimating Jacobian from Metabolomics Data.

    PubMed

    Sun, Xiaoliang; Länger, Bettina; Weckwerth, Wolfram

    2015-01-01

    Inferring dynamics of metabolic networks directly from metabolomics data provides a promising way to elucidate the underlying mechanisms of biological systems, as reported in our previous studies (Weckwerth, 2011; Sun and Weckwerth, 2012; Nägele et al., 2014) by a differential Jacobian approach. The Jacobian is solved from an overdetermined system of equations as JC + CJ(T)  = -2D, called Lyapunov Equation in its generic form, where J is the Jacobian, C is the covariance matrix of metabolomics data, and D is the fluctuation matrix. Lyapunov Equation can be further simplified as the linear form Ax = b. Frequently, this linear equation system is ill-conditioned, i.e., a small variation in the right side b results in a big change in the solution x, thus making the solution unstable and error-prone. At the same time, inaccurate estimation of covariance matrix and uncertainties in the fluctuation matrix bring biases to the solution x. Here, we first reviewed common approaches to circumvent the ill-conditioned problems, including total least squares, Tikhonov regularization, and truncated singular value decomposition. Then, we benchmarked these methods on several in silico kinetic models with small to large perturbations on the covariance and fluctuation matrices. The results identified that the accuracy of the reverse Jacobian is mainly dependent on the condition number of A, the perturbation amplitude of C, and the stiffness of the kinetic models. Our research contributes a systematical comparison of methods to inversely solve Jacobian from metabolomics data. PMID:26636075

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

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    In advanced robot control problems, on-line computation of inverse Jacobian solution is frequently required. Parallel processing architecture is an effective way to reduce computation time. A parallel processing architecture is developed for the inverse Jacobian (inverse differential kinematic equation) of the PUMA arm. The proposed pipeline/parallel algorithm can be inplemented on an IC chip using systolic linear arrays. This implementation requires 27 processing cells and 25 time units. Computation time is thus significantly reduced.

  7. Robust inverse kinematics using damped least squares with dynamic weighting

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

  8. Inverse kinematic-based robot control

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    A fundamental problem which must be resolved in virtually all non-trivial robotic operations is the well-known inverse kinematic question. More specifically, most of the tasks which robots are called upon to perform are specified in Cartesian (x,y,z) space, such as simple tracking along one or more straight line paths or following a specified surfacer with compliant force sensors and/or visual feedback. In all cases, control is actually implemented through coordinated motion of the various links which comprise the manipulator; i.e., in link space. As a consequence, the control computer of every sophisticated anthropomorphic robot must contain provisions for solving the inverse kinematic problem which, in the case of simple, non-redundant position control, involves the determination of the first three link angles, theta sub 1, theta sub 2, and theta sub 3, which produce a desired wrist origin position P sub xw, P sub yw, and P sub zw at the end of link 3 relative to some fixed base frame. Researchers outline a new inverse kinematic solution and demonstrate its potential via some recent computer simulations. They also compare it to current inverse kinematic methods and outline some of the remaining problems which will be addressed in order to render it fully operational. Also discussed are a number of practical consequences of this technique beyond its obvious use in solving the inverse kinematic question.

  9. Joint kinematic calculation based on clinical direct kinematic versus inverse kinematic gait models.

    PubMed

    Kainz, H; Modenese, L; Lloyd, D G; Maine, S; Walsh, H P J; Carty, C P

    2016-06-14

    Most clinical gait laboratories use the conventional gait analysis model. This model uses a computational method called Direct Kinematics (DK) to calculate joint kinematics. In contrast, musculoskeletal modelling approaches use Inverse Kinematics (IK) to obtain joint angles. IK allows additional analysis (e.g. muscle-tendon length estimates), which may provide valuable information for clinical decision-making in people with movement disorders. The twofold aims of the current study were: (1) to compare joint kinematics obtained by a clinical DK model (Vicon Plug-in-Gait) with those produced by a widely used IK model (available with the OpenSim distribution), and (2) to evaluate the difference in joint kinematics that can be solely attributed to the different computational methods (DK versus IK), anatomical models and marker sets by using MRI based models. Eight children with cerebral palsy were recruited and presented for gait and MRI data collection sessions. Differences in joint kinematics up to 13° were found between the Plug-in-Gait and the gait 2392 OpenSim model. The majority of these differences (94.4%) were attributed to differences in the anatomical models, which included different anatomical segment frames and joint constraints. Different computational methods (DK versus IK) were responsible for only 2.7% of the differences. We recommend using the same anatomical model for kinematic and musculoskeletal analysis to ensure consistency between the obtained joint angles and musculoskeletal estimates.

  10. Weighted augmented Jacobian matrix with a variable coefficient method for kinematics mapping of space teleoperation based on human-robot motion similarity

    NASA Astrophysics Data System (ADS)

    Shi, Zhong; Huang, Xuexiang; Hu, Tianjian; Tan, Qian; Hou, Yuzhuo

    2016-10-01

    Space teleoperation is an important space technology, and human-robot motion similarity can improve the flexibility and intuition of space teleoperation. This paper aims to obtain an appropriate kinematics mapping method of coupled Cartesian-joint space for space teleoperation. First, the coupled Cartesian-joint similarity principles concerning kinematics differences are defined. Then, a novel weighted augmented Jacobian matrix with a variable coefficient (WAJM-VC) method for kinematics mapping is proposed. The Jacobian matrix is augmented to achieve a global similarity of human-robot motion. A clamping weighted least norm scheme is introduced to achieve local optimizations, and the operating ratio coefficient is variable to pursue similarity in the elbow joint. Similarity in Cartesian space and the property of joint constraint satisfaction is analysed to determine the damping factor and clamping velocity. Finally, a teleoperation system based on human motion capture is established, and the experimental results indicate that the proposed WAJM-VC method can improve the flexibility and intuition of space teleoperation to complete complex space tasks.

  11. Forward and inverse kinematics of double universal joint robot wrists

    NASA Technical Reports Server (NTRS)

    Williams, Robert L., II

    1991-01-01

    A robot wrist consisting of two universal joints can eliminate the wrist singularity problem found on many individual robots. Forward and inverse position and velocity kinematics are presented for such a wrist having three degrees of freedom. Denavit-Hartenberg parameters are derived to find the transforms required for the kinematic equations. The Omni-Wrist, a commercial double universal joint robot wrist, is studied in detail. There are four levels of kinematic parameters identified for this wrist; three forward and three inverse maps are presented for both position and velocity. These equations relate the hand coordinate frame to the wrist base frame. They are sufficient for control of the wrist standing alone. When the wrist is attached to a manipulator arm; the offset between the two universal joints complicates the solution of the overall kinematics problem. All wrist coordinate frame origins are not coincident, which prevents decoupling of position and orientation for manipulator inverse kinematics.

  12. Inverse kinematics problem in robotics using neural networks

    NASA Technical Reports Server (NTRS)

    Choi, Benjamin B.; Lawrence, Charles

    1992-01-01

    In this paper, Multilayer Feedforward Networks are applied to the robot inverse kinematic problem. The networks are trained with endeffector position and joint angles. After training, performance is measured by having the network generate joint angles for arbitrary endeffector trajectories. A 3-degree-of-freedom (DOF) spatial manipulator is used for the study. It is found that neural networks provide a simple and effective way to both model the manipulator inverse kinematics and circumvent the problems associated with algorithmic solution methods.

  13. Integration of additional constraints to Inverse the differential kinematic model for a nonholonomic and redundant mobile manipulator

    NASA Astrophysics Data System (ADS)

    Akli, Isma; Achour, Noura

    2008-06-01

    This article presents a differential kinematic study for a car-like mobile system carrying a four degrees of freedom manipulator. The generalized coordinates and velocities of the mobile manipulator are required, when the position and the velocity of the end-effector are imposed in the cartesian space. Our approach consists of planning the motion of the mobile platform with make the onboard manipulator able to follow the cartesian trajectory. The resulted generalized coordinates are exploited to calculate the Forward Differential Kinematic Model. Since the mobile manipulator is redundant regarding to the task, we profit from the system characteristics to augment the jacobian matrix, while integrating additional constraints, to inverse the differential kinematic model.

  14. Probability density based gradient projection method for inverse kinematics of a robotic human body model.

    PubMed

    Lura, Derek; Wernke, Matthew; Alqasemi, Redwan; Carey, Stephanie; Dubey, Rajiv

    2012-01-01

    This paper presents the probability density based gradient projection (GP) of the null space of the Jacobian for a 25 degree of freedom bilateral robotic human body model (RHBM). This method was used to predict the inverse kinematics of the RHBM and maximize the similarity between predicted inverse kinematic poses and recorded data of 10 subjects performing activities of daily living. The density function was created for discrete increments of the workspace. The number of increments in each direction (x, y, and z) was varied from 1 to 20. Performance of the method was evaluated by finding the root mean squared (RMS) of the difference between the predicted joint angles relative to the joint angles recorded from motion capture. The amount of data included in the creation of the probability density function was varied from 1 to 10 subjects, creating sets of for subjects included and excluded from the density function. The performance of the GP method for subjects included and excluded from the density function was evaluated to test the robustness of the method. Accuracy of the GP method varied with amount of incremental division of the workspace, increasing the number of increments decreased the RMS error of the method, with the error of average RMS error of included subjects ranging from 7.7° to 3.7°. However increasing the number of increments also decreased the robustness of the method.

  15. 3-D magnetotelluric inversion including topography using deformed hexahedral edge finite elements and direct solvers parallelized on SMP computers - Part I: forward problem and parameter Jacobians

    NASA Astrophysics Data System (ADS)

    Kordy, M.; Wannamaker, P.; Maris, V.; Cherkaev, E.; Hill, G.

    2016-01-01

    We have developed an algorithm, which we call HexMT, for 3-D simulation and inversion of magnetotelluric (MT) responses using deformable hexahedral finite elements that permit incorporation of topography. Direct solvers parallelized on symmetric multiprocessor (SMP), single-chassis workstations with large RAM are used throughout, including the forward solution, parameter Jacobians and model parameter update. In Part I, the forward simulator and Jacobian calculations are presented. We use first-order edge elements to represent the secondary electric field (E), yielding accuracy O(h) for E and its curl (magnetic field). For very low frequencies or small material admittivities, the E-field requires divergence correction. With the help of Hodge decomposition, the correction may be applied in one step after the forward solution is calculated. This allows accurate E-field solutions in dielectric air. The system matrix factorization and source vector solutions are computed using the MKL PARDISO library, which shows good scalability through 24 processor cores. The factorized matrix is used to calculate the forward response as well as the Jacobians of electromagnetic (EM) field and MT responses using the reciprocity theorem. Comparison with other codes demonstrates accuracy of our forward calculations. We consider a popular conductive/resistive double brick structure, several synthetic topographic models and the natural topography of Mount Erebus in Antarctica. In particular, the ability of finite elements to represent smooth topographic slopes permits accurate simulation of refraction of EM waves normal to the slopes at high frequencies. Run-time tests of the parallelized algorithm indicate that for meshes as large as 176 × 176 × 70 elements, MT forward responses and Jacobians can be calculated in ˜1.5 hr per frequency. Together with an efficient inversion parameter step described in Part II, MT inversion problems of 200-300 stations are computable with total run times

  16. Computational neural learning formalisms for manipulator inverse kinematics

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

    An efficient, adaptive neural learning paradigm for addressing the inverse kinematics of redundant manipulators is presented. The proposed methodology exploits the infinite local stability of terminal attractors - a new class of mathematical constructs which provide unique information processing capabilities to artificial neural systems. For robotic applications, synaptic elements of such networks can rapidly acquire the kinematic invariances embedded within the presented samples. Subsequently, joint-space configurations, required to follow arbitrary end-effector trajectories, can readily be computed. In a significant departure from prior neuromorphic learning algorithms, this methodology provides mechanisms for incorporating an in-training skew to handle kinematics and environmental constraints.

  17. An adaptive inverse kinematics algorithm for robot manipulators

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    An adaptive algorithm for solving the inverse kinematics problem for robot manipulators is presented. The algorithm is derived using model reference adaptive control (MRAC) theory and is computationally efficient for online applications. The scheme requires no a priori knowledge of the kinematics of the robot if Cartesian end-effector sensing is available, and it requires knowledge of only the forward kinematics if joint position sensing is used. Computer simulation results are given for the redundant seven-DOF robotics research arm, demonstrating that the proposed algorithm yields accurate joint angle trajectories for a given end-effector position/orientation trajectory.

  18. An inverse kinematic problem with internal sources

    NASA Astrophysics Data System (ADS)

    Pestov, Leonid; Uhlmann, Gunther; Zhou, Hanming

    2015-05-01

    Given a bounded domain M in {{{R}}n} with a conformally Euclidean metric g=ρ d{{x}2}, we consider the inverse problem of recovering a semigeodesic neighborhood of a domain Γ \\subset \\partial M and the conformal factor ρ in the neighborhood from the travel time data (defined below) and the Cartesian coordinates of Γ. We develop an explicit reconstruction procedure for this problem. The key ingredient is the relation between the reconstruction procedure and a Cauchy problem of the conformal Killing equation.

  19. A cut-&-paste strategy for the 3-D inversion of helicopter-borne electromagnetic data - I. 3-D inversion using the explicit Jacobian and a tensor-based formulation

    NASA Astrophysics Data System (ADS)

    Scheunert, M.; Ullmann, A.; Afanasjew, M.; Börner, R.-U.; Siemon, B.; Spitzer, K.

    2016-06-01

    We present an inversion concept for helicopter-borne frequency-domain electromagnetic (HEM) data capable of reconstructing 3-D conductivity structures in the subsurface. Standard interpretation procedures often involve laterally constrained stitched 1-D inversion techniques to create pseudo-3-D models that are largely representative for smoothly varying conductivity distributions in the subsurface. Pronounced lateral conductivity changes may, however, produce significant artifacts that can lead to serious misinterpretation. Still, 3-D inversions of entire survey data sets are numerically very expensive. Our approach is therefore based on a cut-&-paste strategy whereupon the full 3-D inversion needs to be applied only to those parts of the survey where the 1-D inversion actually fails. The introduced 3-D Gauss-Newton inversion scheme exploits information given by a state-of-the-art (laterally constrained) 1-D inversion. For a typical HEM measurement, an explicit representation of the Jacobian matrix is inevitable which is caused by the unique transmitter-receiver relation. We introduce tensor quantities which facilitate the matrix assembly of the forward operator as well as the efficient calculation of the Jacobian. The finite difference forward operator incorporates the displacement currents because they may seriously affect the electromagnetic response at frequencies above 100. Finally, we deliver the proof of concept for the inversion using a synthetic data set with a noise level of up to 5%.

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

    PubMed

    de Angulo, Vicente Ruiz; Torras, Carme

    2008-12-01

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

  1. (p,n) Charge-Exchange Reactions in Inverse Kinematics

    NASA Astrophysics Data System (ADS)

    Lipschutz, Samuel; NSCL E10003 Collaboration

    2014-09-01

    Charge-exchange experiments at intermediate energy yield important information about collective excitations with spin-isospin degrees of freedom. The properties of isovector giant resonances in neutron-rich rare-isotopes provide stringent tests of theoretical models and are important inputs for modeling of astrophysical phenomena. The (p,n) charge-exchange reaction in inverse kinematics has been developed as a new tool for investigating isovector giant resonances in rare isotopes. The technique, which involves the detection of low-energy neutrons that recoil from a hydrogen target, while detecting fast beam-like ejectiles in a magnetic spectrometer, was successfully employed at NSCL to study the 56Ni(p,n) reaction. Continuing with this technique a 16C(p,n) experiment at 100 MeV/u aimed at extracting isovector multipole strengths up to excitation energies of 30 MeV was preformed. The Low Energy Neutron Detector Array (LENDA) and the Versatile Array of Neutron Detectors at Low Energy (VANDLE) were utilized in combination with the Ursinus Liquid Hydrogen Target and the S800 spectrometer to perform this experiment. Preliminary results will be shown. Charge-exchange experiments at intermediate energy yield important information about collective excitations with spin-isospin degrees of freedom. The properties of isovector giant resonances in neutron-rich rare-isotopes provide stringent tests of theoretical models and are important inputs for modeling of astrophysical phenomena. The (p,n) charge-exchange reaction in inverse kinematics has been developed as a new tool for investigating isovector giant resonances in rare isotopes. The technique, which involves the detection of low-energy neutrons that recoil from a hydrogen target, while detecting fast beam-like ejectiles in a magnetic spectrometer, was successfully employed at NSCL to study the 56Ni(p,n) reaction. Continuing with this technique a 16C(p,n) experiment at 100 MeV/u aimed at extracting isovector multipole

  2. Inelastic Proton Scattering on 21Na in Inverse Kinematics

    NASA Astrophysics Data System (ADS)

    Austin, Roby

    2009-10-01

    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 δE-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(α,p)^21Na. [1] PJ Woods et al. Rex-ISOLDE proposal 424 Cern (2003).

  3. Seeing the world topsy-turvy: The primary role of kinematics in biological motion inversion effects

    PubMed Central

    Fitzgerald, Sue-Anne; Brooks, Anna; van der Zwan, Rick; Blair, Duncan

    2014-01-01

    Physical inversion of whole or partial human body representations typically has catastrophic consequences on the observer's ability to perform visual processing tasks. Explanations usually focus on the effects of inversion on the visual system's ability to exploit configural or structural relationships, but more recently have also implicated motion or kinematic cue processing. Here, we systematically tested the role of both on perceptions of sex from upright and inverted point-light walkers. Our data suggest that inversion results in systematic degradations of the processing of kinematic cues. Specifically and intriguingly, they reveal sex-based kinematic differences: Kinematics characteristic of females generally are resistant to inversion effects, while those of males drive systematic sex misperceptions. Implications of the findings are discussed. PMID:25469217

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

    SciTech Connect

    Pain, S. D.; Bardayan, Daniel W; Blackmon, Jeff C; Chae, K. Y.; Chipps, K.; Cizewski, J. A.; Hatarik, Robert; Johnson, Micah; Jones, K. L.; Kapler, R.; Kozub, R. L.; Livesay, Jake; Matei, Catalin; Moazen, Brian; Nesaraja, Caroline D; O'Malley, Patrick; Smith, Michael Scott; Swan, T. P.; Thomas, J. S.; Wilson, Gemma L

    2009-01-01

    The development of high quality radioactive beams has made possible the measurement of transfer reactions in inverse kinematics on unstable nuclei. Measurement of (d,p) reactions on neutron-rich nuclei yield data on the evolution of nuclear structure away from stability, and are of astrophysical interest. Experimentally, (d,p) reactions on heavy (Z=50) fission fragments are complicated by the strongly inverse kinematics, and relatively low beam intensities. Consequently, ejectile detection with high resolution in position and energy, a high dynamic range and a high solid angular coverage is required. The Oak Ridge Rutgers University Barrel Array (ORRUBA) is a new silicon detector array optimized for the measurement of (d,p) reactions in inverse kinematics.

  5. Incremental inverse kinematics based vision servo for autonomous robotic capture of non-cooperative space debris

    NASA Astrophysics Data System (ADS)

    Dong, Gangqi; Zhu, Z. H.

    2016-04-01

    This paper proposed a new incremental inverse kinematics based vision servo approach for robotic manipulators to capture a non-cooperative target autonomously. The target's pose and motion are estimated by a vision system using integrated photogrammetry and EKF algorithm. Based on the estimated pose and motion of the target, the instantaneous desired position of the end-effector is predicted by inverse kinematics and the robotic manipulator is moved incrementally from its current configuration subject to the joint speed limits. This approach effectively eliminates the multiple solutions in the inverse kinematics and increases the robustness of the control algorithm. The proposed approach is validated by a hardware-in-the-loop simulation, where the pose and motion of the non-cooperative target is estimated by a real vision system. The simulation results demonstrate the effectiveness and robustness of the proposed estimation approach for the target and the incremental control strategy for the robotic manipulator.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    NASA Technical Reports Server (NTRS)

    Tahmasebi, Farhad

    2004-01-01

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

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

    PubMed

    Fu, Zhongtao; Yang, Wenyu; Yang, Zhen

    2013-08-01

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

  9. Transfer-induced fission in inverse kinematics: Impact on experimental and evaluated nuclear data bases

    NASA Astrophysics Data System (ADS)

    Farget, F.; Caamaño, M.; Ramos, D.; Rodrıguez-Tajes, C.; Schmidt, K.-H.; Audouin, L.; Benlliure, J.; Casarejos, E.; Clément, E.; Cortina, D.; Delaune, O.; Derkx, X.; Dijon, A.; Doré, D.; Fernández-Domınguez, B.; Gaudefroy, L.; Golabek, C.; Heinz, A.; Jurado, B.; Lemasson, A.; Paradela, C.; Roger, T.; Salsac, M. D.; Schmitt, C.

    2015-12-01

    Inverse kinematics is a new tool to study nuclear fission. Its main advantage is the possibility to measure with an unmatched resolution the atomic number of fission fragments, leading to new observables in the properties of fission-fragment distributions. In addition to the resolution improvement, the study of fission based on nuclear collisions in inverse kinematics beneficiates from a larger view with respect to the neutron-induced fission, as in a single experiment the number of fissioning systems and the excitation energy range are widden. With the use of spectrometers, mass and kinetic-energy distributions may now be investigated as a function of the proton and neutron number sharing. The production of fissioning nuclei in transfer reactions allows studying the isotopic yields of fission fragments as a function of the excitation energy. The higher excitation energy resulting in the fusion reaction leading to the compound nucleus 250Cf at an excitation energy of 45MeV is also presented. With the use of inverse kinematics, the charge polarisation of fragments at scission is now revealed with high precision, and it is shown that it cannot be neglected, even at higher excitation energies. In addition, the kinematical properties of the fragments inform on the deformation configuration at scission.

  10. Rapid kinematic slip inversion with regional geophysical data: towards site-specific tsunami intensity forecasts.

    NASA Astrophysics Data System (ADS)

    Melgar, D.; Bock, Y.

    2014-12-01

    Rapid kinematic slip inversions immediately following earthquake rupture is traditionally limited to teleseismic data and delayed many hours after large events. Regional data such as strong motion is difficult to incorporate quickly into images of the source process because baseline offsets render the long period portion of the recording unreliable. Recently it's been demonstrated that high rate GPS can potentially produce rapid slip inversions for large events but is limited to very long periods. With an example of the 2011 M9 Tohoku-oki event we will demonstrate that the optimal on-the-fly combination of GPS and strong motion through a seismogeodetic Kalman filter produces reliable, broadband strong motion displacement and velocity waveforms that can be used for kinematic inversion. Through joint inversion of displacement and velocity waveforms we will show that it is possible to obtain a broadband image of the source. Furthermore, we will also show that it is possible to include offshore geophysical observables such as sea surface measurements of tsunami propagation from GPS buoys and ocean bottom pressure sensors into the kinematic inversion. These data better constrain the shallowest part of rupture. We will use the time-dependent deformation of bathymetry predicted from the inversion results as an initial condition for tsunami propagation and inundation modeling. Through a comparison to post-event survey observations we will demonstrate that it is possible to reproduce the inundation pattern along the coastline in great detail and argue that detailed site-specific forecast of tsunami intensity is achievable with current methods and instrumentation.

  11. Neutron capture surrogate reaction on 75As in inverse kinematics using (d,pγ)

    NASA Astrophysics Data System (ADS)

    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.

    2010-03-01

    The 75As(d,pγ) 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 γ-ray from 76As in coincidence with ejected protons, from exciting 76As above the neutron separation energy populating a compound state, was measured. A tight geometry of four segmented germanium clover γ-ray detectors together with eight ORRUBA-type silicon-strip charged-particle detectors was used to optimize geometric acceptance. The preliminary analysis of the 75As experiment, and the efficacy and future plans of the (d,pγ) surrogate campaign in inverse kinematics, are discussed.

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

    SciTech Connect

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

    2009-11-09

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

  13. The SOFIA experiment: Measurement of 236U fission fragment yields in inverse kinematics

    NASA Astrophysics Data System (ADS)

    Grente, L.; Taïeb, J.; Chatillon, A.; Martin, J.-F.; Pellereau, É.; Boutoux, G.; Gorbinet, T.; Bélier, G.; Laurent, B.; Alvarez-Pol, H.; Ayyad, Y.; Benlliure, J.; Caamaño, M.; Audouin, L.; Casarejos, E.; Cortina-Gil, D.; Farget, F.; Fernández-Domínguez, B.; Heinz, A.; Jurado, B.; Kelić-Heil, A.; Kurz, N.; Lindberg, S.; Löher, B.; Nociforo, C.; Paradela, C.; Pietri, S.; Ramos, D.; Rodriguez-Sanchez, J.-L.; Rodríguez-Tajes, C.; Rossi, D.; Schmidt, K.-H.; Simon, H.; Tassan-Got, L.; Törnqvist, H.; Vargas, J.; Voss, B.; Weick, H.; Yan, Y.

    2016-06-01

    The SOFIA (Studies On FIssion with Aladin) experiment aims at measuring fission-fragments isotopic yields with high accuracy using inverse kinematics at relativistic energies. This experimental technique allows to fully identify the fission fragments in nuclear charge and mass number, thus providing very accurate isotopic yields for low energy fission of a large variety of fissioning systems. This report focuses on the latest results obtained with this set-up concerning electromagnetic-induced fission of 236U.

  14. Exclusive measurements of quasi-free proton scattering reactions in inverse and complete kinematics

    NASA Astrophysics Data System (ADS)

    Panin, V.; Taylor, J. T.; Paschalis, S.; Wamers, F.; Aksyutina, Y.; Alvarez-Pol, H.; Aumann, T.; Bertulani, C. A.; Boretzky, K.; Caesar, C.; Chartier, M.; Chulkov, L. V.; Cortina-Gil, D.; Enders, J.; Ershova, O.; Geissel, H.; Gernhäuser, R.; Heil, M.; Johansson, H. T.; Jonson, B.; Kelić-Heil, A.; Langer, C.; Le Bleis, T.; Lemmon, R.; Nilsson, T.; Petri, M.; Plag, R.; Reifarth, R.; Rossi, D.; Scheit, H.; Simon, H.; Weick, H.; Wimmer, C.

    2016-02-01

    Quasi-free scattering reactions of the type (p , 2 p) were measured for the first time exclusively in complete and inverse kinematics, using a 12C beam at an energy of ˜ 400 MeV /u as a benchmark. This new technique has been developed to study the single-particle structure of exotic nuclei in experiments with radioactive-ion beams. The outgoing pair of protons and the fragments were measured simultaneously, enabling an unambiguous identification of the reaction channels and a redundant measurement of the kinematic observables. Both valence and deeply-bound nucleon orbits are probed, including those leading to unbound states of the daughter nucleus. Exclusive (p , 2 p) cross sections of 15.8(18) mb, 1.9(2) mb and 1.5(2) mb to the low-lying 0p-hole states overlapping with the ground state (3 /2-) and with the bound excited states of 11B at 2.125 MeV (1 /2-) and 5.02 MeV (3 /2-), respectively, were determined via γ-ray spectroscopy. Particle-unstable deep-hole states, corresponding to proton removal from the 0s-orbital, were studied via the invariant-mass technique. Cross sections and momentum distributions were extracted and compared to theoretical calculations employing the eikonal formalism. The obtained results are in a good agreement with this theory and with direct-kinematics experiments. The dependence of the proton-proton scattering kinematics on the internal momentum of the struck proton and on its separation energy was investigated for the first time in inverse kinematics employing a large-acceptance measurement.

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

    USGS Publications Warehouse

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

    2004-01-01

    We perform inverse kinematic and forward dynamic models of the M 7.9 2002 Denali fault, Alaska, earthquake to shed light on the rupture process and dynamics of this event, which took place on a geometrically complex fault system in central Alaska. We use a combination of local seismic and Global Positioning System (GPS) data for our kinematic inversion and find that the slip distribution of this event is characterized by three major asperities on the Denali fault. The rupture nucleated on the Susitna Glacier thrust fault, and after a pause, propagated onto the strike-slip Denali fault. Approximately 216 km to the east, the rupture abandoned the Denali fault in favor of the more southwesterly directed Totschunda fault. Three-dimensional dynamic models of this event indicate that the abandonment of the Denali fault for the Totschunda fault can be explained by the Totschunda fault's more favorable orientation with respect to the local stress field. However, a uniform tectonic stress field cannot explain the complex slip pattern in this event. We also find that our dynamic models predict discontinuous rupture from the Denali to Totschunda fault segments. Such discontinuous rupture helps to qualitatively improve our kinematic inverse models. Two principal implications of our study are (1) a combination of inverse and forward modeling can bring insight into earthquake processes that are not possible with either technique alone, and (2) the stress field on geometrically complex fault systems is most likely not due to a uniform tectonic stress field that is resolved onto fault segments of different orientations; rather, other forms of stress heterogeneity must be invoked to explain the observed slip patterns.

  16. A New Artificial Neural Network Approach in Solving Inverse Kinematics of Robotic Arm (Denso VP6242).

    PubMed

    Almusawi, Ahmed R J; Dülger, L Canan; Kapucu, Sadettin

    2016-01-01

    This paper presents a novel inverse kinematics solution for robotic arm based on artificial neural network (ANN) architecture. The motion of robotic arm is controlled by the kinematics of ANN. A new artificial neural network approach for inverse kinematics is proposed. The novelty of the proposed ANN is the inclusion of the feedback of current joint angles configuration of robotic arm as well as the desired position and orientation in the input pattern of neural network, while the traditional ANN has only the desired position and orientation of the end effector in the input pattern of neural network. In this paper, a six DOF Denso robotic arm with a gripper is controlled by ANN. The comprehensive experimental results proved the applicability and the efficiency of the proposed approach in robotic motion control. The inclusion of current configuration of joint angles in ANN significantly increased the accuracy of ANN estimation of the joint angles output. The new controller design has advantages over the existing techniques for minimizing the position error in unconventional tasks and increasing the accuracy of ANN in estimation of robot's joint angles. PMID:27610129

  17. A New Artificial Neural Network Approach in Solving Inverse Kinematics of Robotic Arm (Denso VP6242)

    PubMed Central

    Dülger, L. Canan; Kapucu, Sadettin

    2016-01-01

    This paper presents a novel inverse kinematics solution for robotic arm based on artificial neural network (ANN) architecture. The motion of robotic arm is controlled by the kinematics of ANN. A new artificial neural network approach for inverse kinematics is proposed. The novelty of the proposed ANN is the inclusion of the feedback of current joint angles configuration of robotic arm as well as the desired position and orientation in the input pattern of neural network, while the traditional ANN has only the desired position and orientation of the end effector in the input pattern of neural network. In this paper, a six DOF Denso robotic arm with a gripper is controlled by ANN. The comprehensive experimental results proved the applicability and the efficiency of the proposed approach in robotic motion control. The inclusion of current configuration of joint angles in ANN significantly increased the accuracy of ANN estimation of the joint angles output. The new controller design has advantages over the existing techniques for minimizing the position error in unconventional tasks and increasing the accuracy of ANN in estimation of robot's joint angles.

  18. Inverse kinematics (p, n) reactions studies using the WINDS slow neutron detector and the SAMURAI spectrometer

    NASA Astrophysics Data System (ADS)

    Yasuda, J.; Sasano, M.; Zegers, R. G. T.; Baba, H.; Chao, W.; Dozono, M.; Fukuda, N.; Inabe, N.; Isobe, T.; Jhang, G.; Kameda, D.; Kubo, T.; Kurata-Nishimura, M.; Milman, E.; Motobayashi, T.; Otsu, H.; Panin, V.; Powell, W.; Sakai, H.; Sako, M.; Sato, H.; Shimizu, Y.; Stuhl, L.; Suzuki, H.; Tangwancharoen, S.; Takeda, H.; Uesaka, T.; Yoneda, K.; Zenihiro, J.; Kobayashi, T.; Sumikama, T.; Tako, T.; Nakamura, T.; Kondo, Y.; Togano, Y.; Shikata, M.; Tsubota, J.; Yako, K.; Shimoura, S.; Ota, S.; Kawase, S.; Kubota, Y.; Takaki, M.; Michimasa, S.; Kisamori, K.; Lee, C. S.; Tokieda, H.; Kobayashi, M.; Koyama, S.; Kobayashi, N.; Wakasa, T.; Sakaguchi, S.; Krasznahorkay, A.; Murakami, T.; Nakatsuka, N.; Kaneko, M.; Matsuda, Y.; Mucher, D.; Reichert, S.; Bazin, D.; Lee, J. W.

    2016-06-01

    We have combined the low-energy neutron detector WINDS (Wide-angle Inverse-kinematics Neutron Detectors for SHARAQ) and the SAMURAI spectrometer at RIKEN Nishina Center RI Beam Factory (RIBF) in order to perform (p, n) reactions in inverse kinematics for unstable nuclei in the mass region around A ∼ 100 . In this setup, WINDS is used for detecting recoil neutrons and the SAMURAI spectrometer is used for tagging decay channel of heavy residue. The first experiment by using the setup was performed to study Gamow-Teller transitions from 132Sn in April 2014. The atomic number Z and mass-to-charge ratio A / Q of the beam residues were determined from the measurements of time of flight, magnetic rigidity and energy loss. The obtained A / Q and Z resolutions were σA/Q = 0.14 % and σZ = 0.22 , respectively. Furthermore, owing to the large momentum acceptance (50 %) of SAMURAI, the beam residues associated with the γ , 1n and 2n decay channel were measured in the same magnetic field setting. The kinematic loci of the measured recoil neutron energy and laboratory angle are clearly seen. It shows that the excitation energy up to about 20 MeV can be reconstructed.

  19. A New Artificial Neural Network Approach in Solving Inverse Kinematics of Robotic Arm (Denso VP6242)

    PubMed Central

    Dülger, L. Canan; Kapucu, Sadettin

    2016-01-01

    This paper presents a novel inverse kinematics solution for robotic arm based on artificial neural network (ANN) architecture. The motion of robotic arm is controlled by the kinematics of ANN. A new artificial neural network approach for inverse kinematics is proposed. The novelty of the proposed ANN is the inclusion of the feedback of current joint angles configuration of robotic arm as well as the desired position and orientation in the input pattern of neural network, while the traditional ANN has only the desired position and orientation of the end effector in the input pattern of neural network. In this paper, a six DOF Denso robotic arm with a gripper is controlled by ANN. The comprehensive experimental results proved the applicability and the efficiency of the proposed approach in robotic motion control. The inclusion of current configuration of joint angles in ANN significantly increased the accuracy of ANN estimation of the joint angles output. The new controller design has advantages over the existing techniques for minimizing the position error in unconventional tasks and increasing the accuracy of ANN in estimation of robot's joint angles. PMID:27610129

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

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  1. Simulation for thick-target yields of transmutation reactions on radioactive targets, based on inverse kinematics

    NASA Astrophysics Data System (ADS)

    Ebata, Shuichiro; Aikawa, Masayuki; Imai, Shotaro

    2016-06-01

    To dispose of long-lived fission products (LLFP) ejected from nuclear reactor plants is one of the most important tasks on nuclear physics and engineering. The experiments with the radiative target are limited, due to the high radioactivity and chemical property of the target. In consequence, the nuclear reaction data for LLFP are insufficient. In this work, we propose a feasible method to obtain the data for radiative targets using inverse kinematics and simulate specific systems to evaluate the thick-target yields of the nuclear transmutation reactions for LLFP.

  2. {sup 128}Xe Lifetime Measurement Using the Coulex-Plunger Technique in Inverse Kinematics

    SciTech Connect

    Konstantinopoulos, T.; Lagoyannis, A.; Harissopulos, S.; Dewald, A.; Rother, W.; Ilie, G.; Jones, P.; Rakhila, P.; Greenlees, P.; Grahn, T.; Julin, R.; Balabanski, D. L.

    2008-05-12

    The lifetimes of the lowest collective yrast and non-yrast states in {sup 128}Xe were measured in a Coulomb excitation experiment using the recoil distance method (RDM) in inverse kinematics. Hereby, the Cologne plunger apparatus was employed together with the JUROGAM spectrometer. Excited states in {sup 128}Xe were populated using a {sup 128}Xe beam impinging on a {sup nat}Fe target with E({sup 128}Xe){approx_equal}525 MeV. Recoils were detected by means of an array of solar cells placed at forward angles. Recoil-gated {gamma}-spectra were measured at different plunger distances.

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    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

  4. Inverse hydrograph routing optimization model based on the kinematic wave approach

    NASA Astrophysics Data System (ADS)

    Saghafian, B.; Jannaty, M. H.; Ezami, N.

    2015-08-01

    This article presents and validates the inverse flood hydrograph routing optimization model under kinematic wave (KW) approximation in order to produce the upstream (inflow) hydrograph, given the downstream (outflow) hydrograph of a river reach. The cost function involves minimization of the error between the observed outflow hydrograph and the corresponding directly routed outflow hydrograph. Decision variables are the inflow hydrograph ordinates. The KW and genetic algorithm (GA) are coupled, representing the selected methods of direct routing and optimization, respectively. A local search technique is also enforced to achieve better agreement of the routed outflow hydrograph with the observed hydrograph. Computer programs handling the direct flood routing, cost function and local search are linked with the optimization model. The results show that the case study inflow hydrographs obtained by the GA were reconstructed with accuracy. It was also concluded that the coupled KW-GA model framework can perform inverse hydrograph routing with numerical stability.

  5. Inverse Kinematics for Upper Limb Compound Movement Estimation in Exoskeleton-Assisted Rehabilitation.

    PubMed

    Cortés, Camilo; de Los Reyes-Guzmán, Ana; Scorza, Davide; Bertelsen, Álvaro; Carrasco, Eduardo; Gil-Agudo, Ángel; Ruiz-Salguero, Oscar; Flórez, Julián

    2016-01-01

    Robot-Assisted Rehabilitation (RAR) is relevant for treating patients affected by nervous system injuries (e.g., stroke and spinal cord injury). The accurate estimation of the joint angles of the patient limbs in RAR is critical to assess the patient improvement. The economical prevalent method to estimate the patient posture in Exoskeleton-based RAR is to approximate the limb joint angles with the ones of the Exoskeleton. This approximation is rough since their kinematic structures differ. Motion capture systems (MOCAPs) can improve the estimations, at the expenses of a considerable overload of the therapy setup. Alternatively, the Extended Inverse Kinematics Posture Estimation (EIKPE) computational method models the limb and Exoskeleton as differing parallel kinematic chains. EIKPE has been tested with single DOF movements of the wrist and elbow joints. This paper presents the assessment of EIKPE with elbow-shoulder compound movements (i.e., object prehension). Ground-truth for estimation assessment is obtained from an optical MOCAP (not intended for the treatment stage). The assessment shows EIKPE rendering a good numerical approximation of the actual posture during the compound movement execution, especially for the shoulder joint angles. This work opens the horizon for clinical studies with patient groups, Exoskeleton models, and movements types. PMID:27403420

  6. Inverse Kinematics for Upper Limb Compound Movement Estimation in Exoskeleton-Assisted Rehabilitation.

    PubMed

    Cortés, Camilo; de Los Reyes-Guzmán, Ana; Scorza, Davide; Bertelsen, Álvaro; Carrasco, Eduardo; Gil-Agudo, Ángel; Ruiz-Salguero, Oscar; Flórez, Julián

    2016-01-01

    Robot-Assisted Rehabilitation (RAR) is relevant for treating patients affected by nervous system injuries (e.g., stroke and spinal cord injury). The accurate estimation of the joint angles of the patient limbs in RAR is critical to assess the patient improvement. The economical prevalent method to estimate the patient posture in Exoskeleton-based RAR is to approximate the limb joint angles with the ones of the Exoskeleton. This approximation is rough since their kinematic structures differ. Motion capture systems (MOCAPs) can improve the estimations, at the expenses of a considerable overload of the therapy setup. Alternatively, the Extended Inverse Kinematics Posture Estimation (EIKPE) computational method models the limb and Exoskeleton as differing parallel kinematic chains. EIKPE has been tested with single DOF movements of the wrist and elbow joints. This paper presents the assessment of EIKPE with elbow-shoulder compound movements (i.e., object prehension). Ground-truth for estimation assessment is obtained from an optical MOCAP (not intended for the treatment stage). The assessment shows EIKPE rendering a good numerical approximation of the actual posture during the compound movement execution, especially for the shoulder joint angles. This work opens the horizon for clinical studies with patient groups, Exoskeleton models, and movements types.

  7. Inverse Kinematics for Upper Limb Compound Movement Estimation in Exoskeleton-Assisted Rehabilitation

    PubMed Central

    Cortés, Camilo; de los Reyes-Guzmán, Ana; Scorza, Davide; Bertelsen, Álvaro; Carrasco, Eduardo; Gil-Agudo, Ángel; Ruiz-Salguero, Oscar; Flórez, Julián

    2016-01-01

    Robot-Assisted Rehabilitation (RAR) is relevant for treating patients affected by nervous system injuries (e.g., stroke and spinal cord injury). The accurate estimation of the joint angles of the patient limbs in RAR is critical to assess the patient improvement. The economical prevalent method to estimate the patient posture in Exoskeleton-based RAR is to approximate the limb joint angles with the ones of the Exoskeleton. This approximation is rough since their kinematic structures differ. Motion capture systems (MOCAPs) can improve the estimations, at the expenses of a considerable overload of the therapy setup. Alternatively, the Extended Inverse Kinematics Posture Estimation (EIKPE) computational method models the limb and Exoskeleton as differing parallel kinematic chains. EIKPE has been tested with single DOF movements of the wrist and elbow joints. This paper presents the assessment of EIKPE with elbow-shoulder compound movements (i.e., object prehension). Ground-truth for estimation assessment is obtained from an optical MOCAP (not intended for the treatment stage). The assessment shows EIKPE rendering a good numerical approximation of the actual posture during the compound movement execution, especially for the shoulder joint angles. This work opens the horizon for clinical studies with patient groups, Exoskeleton models, and movements types. PMID:27403420

  8. Integrated Analytic and Linearized Inverse Kinematics for Precise Full Body Interactions

    NASA Astrophysics Data System (ADS)

    Boulic, Ronan; Raunhardt, Daniel

    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.

  9. Inversion kinematics at deep-seated gravity slope deformations revealed by trenching techniques

    NASA Astrophysics Data System (ADS)

    Pasquaré Mariotto, Federico; Tibaldi, Alessandro

    2016-03-01

    We compare data from three deep-seated gravitational slope deformations (DSGSDs) where palaeoseismological techniques were applied in artificial trenches. At all trenches, located in metamorphic rocks of the Italian Alps, there is evidence of extensional deformation given by normal movements along slip planes dipping downhill or uphill, and/or fissures, as expected in gravitational failure. However, we document and illustrate - with the aid of trenching - evidence of reverse movements. The reverse slips occurred mostly along the same planes along which normal slip occurred, and they produced drag folds in unconsolidated Holocene sediments as well as the superimposition of substrate rocks on Holocene sediments. The studied trenches indicate that reverse slip might occur not only at the toe portions of DSGSDs but also in their central-upper portions. When the age relationships between the two deformation kinematics can be determined, they clearly indicate that reverse slips postdate normal ones. Our data suggest that, during the development of long-lived DSGSDs, inversion kinematics may occur in different sectors of the unstable rock mass. The inversion is interpreted as due either to locking of the frontal blocks of a DSGSD or to the relative decrease in the rate of downward movement in the frontal blocks with respect to the rear blocks.

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

    NASA Technical Reports Server (NTRS)

    Naccarato, Frank; Hughes, Peter

    1989-01-01

    A new class of robotic arm consists of a periodic sequence of truss substructures, each of which has several variable-length members. Such variable-geometry-truss manipulator (VGTMs) are inherently highly redundant and promise a significant increase in dexterity over conventional anthropomorphic manipulators. This dexterity may be exploited for both obstacle avoidance and controlled deployment in complex workspaces. The inverse kinematics problem for such unorthodox manipulators, however, becomes complex because of the large number of degrees of freedom, and conventional solutions to the inverse kinematics problem become inefficient because of the high degree of redundancy. A solution is presented to this problem based on a spline-like reference curve for the manipulator's shape. Such an approach has a number of advantages: (1) direct, intuitive manipulation of shape; (2) reduced calculation time; and (3) direct control over the effective degree of redundancy of the manipulator. Furthermore, although the algorithm was developed primarily for variable-geometry-truss manipulators, it is general enough for application to a number of manipulator designs.

  11. Landslide Kinematical Analysis through Inverse Numerical Modelling and Differential SAR Interferometry

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  12. Kinematically redundant robot manipulators

    NASA Technical Reports Server (NTRS)

    Baillieul, J.; Hollerbach, J.; Brockett, R.; Martin, D.; Percy, R.; Thomas, R.

    1987-01-01

    Research on control, design and programming of kinematically redundant robot manipulators (KRRM) is discussed. These are devices in which there are more joint space degrees of freedom than are required to achieve every position and orientation of the end-effector necessary for a given task in a given workspace. The technological developments described here deal with: kinematic programming techniques for automatically generating joint-space trajectories to execute prescribed tasks; control of redundant manipulators to optimize dynamic criteria (e.g., applications of forces and moments at the end-effector that optimally distribute the loading of actuators); and design of KRRMs to optimize functionality in congested work environments or to achieve other goals unattainable with non-redundant manipulators. Kinematic programming techniques are discussed, which show that some pseudo-inverse techniques that have been proposed for redundant manipulator control fail to achieve the goals of avoiding kinematic singularities and also generating closed joint-space paths corresponding to close paths of the end effector in the workspace. The extended Jacobian is proposed as an alternative to pseudo-inverse techniques.

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

    NASA Astrophysics Data System (ADS)

    Xu, Wenfu; She, Yu; Xu, Yangsheng

    2014-12-01

    Redundant space manipulators, including Space Station Remote Manipulator System (SSRMS), Special Purpose Dexterous Manipulator (SPDM) and European Robotic Arm (ERA), have been playing important roles in the construction and maintenance of International Space Station (ISS). They all have 7 revolute joints arranged in similar configurations, and are referred to as SSRMS-type manipulators. When a joint is locked in an arbitrary position due to some failures, a 7R manipulator degrades to a 6R manipulator. Without a spherical wrist or three consecutive parallel joints, the inverse kinematics of the 6R manipulator is very complex. In this paper, we propose effective methods to resolve the inverse kinematics for different cases of any joint locked in an arbitrary position. Firstly, configuration characteristics of the SSRMS-type redundant manipulators are analyzed. Then, an existing of closed-form inverse kinematics is discussed for locking different joints. Secondly, D-H frames and corresponding D-H parameters of the new 6-DOF manipulator formed by locking a joint in an arbitrary position are re-constructed. A unified table is then created to describe the kinematics for all possible cases of single joint locking failure. Thirdly, completely analytical and semi-analytical methods are presented to solve the inverse kinematics equations, and the former is used for locking joint 1, 2, 6 or 7 while the latter for locking joint 3, 4 or 5. Finally, typical cases for single joint locking are studied. The results verify the proposed methods.

  14. Kinematics

    NASA Astrophysics Data System (ADS)

    Beggs, J. S.

    The notation, theory, and applications of kinematical concepts are explored in detail. Transformations are defined for coordinates, vector components, direction cosines, and the inertia matrix. Attitude is investigated in terms of characteristics of the direction cosine matrix, Euler's angles and angular placement theorem, and inertial navigation. Displacement and motion are considered, as are Euler's parameters as quaternions, and non-Cartesian coordinate systems. Applications of kinematics to gyro output transitions from one attitude to another, to linkage mechanisms, and to contacting surfaces are presented. Geometrical optics problems are examined, together with the dynamics of rigid bodies, coning, and the kinematics of steering a tractor and trailer.

  15. Development of a new Recoil Distance Technique using Coulomb Excitation in Inverse Kinematics

    SciTech Connect

    Rother, Wolfram; Dewald, Alfred; Ilie, Gabriela; Pissulla, Thomas; Melon, Barbara; Jolie, Jan; Pascovici, Gheorghe; Iwasaki, Hironori; Hackstein, Matthias; Zell, Karl-Oskar; Julin, Rauno; Jones, Peter; Greenlees, Paul; Rahkila, Panu; Uusitalo, Juha; Scholey, Cath; Harissopulos, Sotirios; Lagoyannis, Anastasios; Konstantinopoulos, Theodore; Grahn, Tuomas

    2009-01-28

    We report on an experiment using Coulomb excitation in inverse kinematics in combination with the plunger technique for measuring lifetimes of excited states of the projectiles. Aside from the investigation of E(5) features in {sup 128}Xe, the aim was to explore the special features of such experiments which are also suited to be used with radioactive beams. The measurement was performed at the JYFL with the Koeln coincidence plunger device and the JUROGAM spectrometer using a {sup 128}Xe beam impinging on a {sup nat}Fe target at a beam energy of 525 MeV. Recoils were detected by means of 32 solar cells placed at extreme forward angles. Particle-gated {gamma}-singles and {gamma}{gamma}-coincidences were measured at different target-degrader distances. Details of the experiment and first results are presented.

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

    The presentations explores kinematics of the Wenchaun-Beichuan earthquake using data from ALOS, Envisat, and teleseismic recordings. Topics include geomorphic mapping, ALOS PALSAR range offsets, ALOS PALSAR interferometry, Envisat IM interferometry, Envisat ScanSAR, Joint GPS-InSAR inversion, and joint GPS-teleseismic inversion (static and kinematic).

  17. Algorithmic vs. finite difference Jacobians for infrared atmospheric radiative transfer

    NASA Astrophysics Data System (ADS)

    Schreier, Franz; Gimeno García, Sebastián; Vasquez, Mayte; Xu, Jian

    2015-10-01

    Jacobians, i.e. partial derivatives of the radiance and transmission spectrum with respect to the atmospheric state parameters to be retrieved from remote sensing observations, are important for the iterative solution of the nonlinear inverse problem. Finite difference Jacobians are easy to implement, but computationally expensive and possibly of dubious quality; on the other hand, analytical Jacobians are accurate and efficient, but the implementation can be quite demanding. GARLIC, our "Generic Atmospheric Radiation Line-by-line Infrared Code", utilizes algorithmic differentiation (AD) techniques to implement derivatives w.r.t. atmospheric temperature and molecular concentrations. In this paper, we describe our approach for differentiation of the high resolution infrared and microwave spectra and provide an in-depth assessment of finite difference approximations using "exact" AD Jacobians as a reference. The results indicate that the "standard" two-point finite differences with 1 K and 1% perturbation for temperature and volume mixing ratio, respectively, can exhibit substantial errors, and central differences are significantly better. However, these deviations do not transfer into the truncated singular value decomposition solution of a least squares problem. Nevertheless, AD Jacobians are clearly recommended because of the superior speed and accuracy.

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

    SciTech Connect

    Unseren, M.A.

    1993-04-01

    The report discusses the orientation tracking control problem for a kinematically redundant, autonomous manipulator moving in a three dimensional workspace. The orientation error is derived using the normalized quaternion error method of Ickes, the Luh, Walker, and Paul error method, and a method suggested here utilizing the Rodrigues parameters, all of which are expressed in terms of normalized quaternions. The analytical time derivatives of the orientation errors are determined. The latter, along with the translational velocity error, form a dosed loop kinematic velocity model of the manipulator using normalized quaternion and translational position feedback. An analysis of the singularities associated with expressing the models in a form suitable for solving the inverse kinematics problem is given. Two redundancy resolution algorithms originally developed using an open loop kinematic velocity model of the manipulator are extended to properly take into account the orientation tracking control problem. This report furnishes the necessary mathematical framework required prior to experimental implementation of the orientation tracking control schemes on the seven axis CESARm research manipulator or on the seven-axis Robotics Research K1207i dexterous manipulator, the latter of which is to be delivered to the Oak Ridge National Laboratory in 1993.

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

    NASA Technical Reports Server (NTRS)

    Williams, Robert L., III

    1992-01-01

    This paper presents three methods to solve the inverse position kinematics position problem of the double universal joint attached to a manipulator: (1) an analytical solution for two specific cases; (2) an approximate closed form solution based on ignoring the wrist offset; and (3) an iterative method which repeats closed form position and orientation calculations until the solution is achieved. Several manipulators are used to demonstrate the solution methods: cartesian, cylindrical, spherical, and an anthropomorphic articulated arm, based on the Flight Telerobotic Servicer (FTS) arm. A singularity analysis is presented for the double universal joint wrist attached to the above manipulator arms. While the double universal joint wrist standing alone is singularity-free in orientation, the singularity analysis indicates the presence of coupled position/orientation singularities of the spherical and articulated manipulators with the wrist. The cartesian and cylindrical manipulators with the double universal joint wrist were found to be singularity-free. The methods of this paper can be implemented in a real-time controller for manipulators with the double universal joint wrist. Such mechanically dextrous systems could be used in telerobotic and industrial applications, but further work is required to avoid the singularities.

  20. Investigation of the structure of light exotic nuclei by proton elastic scattering in inverse kinematics

    SciTech Connect

    Alkhazov, G. D.; Vorobyov, A. A.; Dobrovolsky, A. V. Inglessi, A. G.; Korolev, G. A.; Khanzadeev, A. V.

    2015-05-15

    In order to study the spatial structure of exotic nuclei, it was proposed at the Petersburg Nuclear Physics Institute (PNPI) to measure the differential cross section for small-angle proton elastic scattering in inverse kinematics. Several experiments in beams of 0.7-GeV/nucleon exotic nuclei were performed at the heavy-ion accelerator facility of GSI (Gesellschaft für Schwerionenforschung, Darmstadt, Germany) by using the IKAR ionization spectrometer developed at PNPI. The IKAR ionization chamber filled with hydrogen at a pressure of 10 bar served simultaneously as a target and as a recoil-proton detector, which measured the recoil-proton energy. The beam-particle scattering angle was also measured. The results obtained for the cross sections in question were analyzed on the basis of the Glauber-Sitenko theory using phenomenological nuclear-density distributions with two free parameters. Nuclear-matter distributions and root-mean-square radii were found for the nuclei under investigation. The size of the halo in the {sup 6}He, {sup 8}He, {sup 11}Li, and {sup 14}Be nuclei was determined among other things. Information about neutron distributions in nuclei was deduced by combining the data obtained here with the known values of the radii of proton distributions. A sizable neutron skin was revealed in the {sup 8}Li, {sup 9}Li, and {sup 12}Be nuclei.

  1. Investigation of the structure of light exotic nuclei by proton elastic scattering in inverse kinematics

    NASA Astrophysics Data System (ADS)

    Alkhazov, G. D.; Vorobyov, A. A.; Dobrovolsky, A. V.; Inglessi, A. G.; Korolev, G. A.; Khanzadeev, A. V.

    2015-05-01

    In order to study the spatial structure of exotic nuclei, it was proposed at the Petersburg Nuclear Physics Institute (PNPI) to measure the differential cross section for small-angle proton elastic scattering in inverse kinematics. Several experiments in beams of 0.7-GeV/nucleon exotic nuclei were performed at the heavy-ion accelerator facility of GSI (Gesellschaft für Schwerionenforschung, Darmstadt, Germany) by using the IKAR ionization spectrometer developed at PNPI. The IKAR ionization chamber filled with hydrogen at a pressure of 10 bar served simultaneously as a target and as a recoil-proton detector, which measured the recoil-proton energy. The beam-particle scattering angle was also measured. The results obtained for the cross sections in question were analyzed on the basis of the Glauber-Sitenko theory using phenomenological nuclear-density distributions with two free parameters. Nuclear-matter distributions and root-mean-square radii were found for the nuclei under investigation. The size of the halo in the 6He, 8He, 11Li, and 14Be nuclei was determined among other things. Information about neutron distributions in nuclei was deduced by combining the data obtained here with the known values of the radii of proton distributions. A sizable neutron skin was revealed in the 8Li, 9Li, and 12Be nuclei.

  2. Cerebellum-inspired neural network solution of the inverse kinematics problem.

    PubMed

    Asadi-Eydivand, Mitra; Ebadzadeh, Mohammad Mehdi; Solati-Hashjin, Mehran; Darlot, Christian; Abu Osman, Noor Azuan

    2015-12-01

    The demand today for more complex robots that have manipulators with higher degrees of freedom is increasing because of technological advances. Obtaining the precise movement for a desired trajectory or a sequence of arm and positions requires the computation of the inverse kinematic (IK) function, which is a major problem in robotics. The solution of the IK problem leads robots to the precise position and orientation of their end-effector. We developed a bioinspired solution comparable with the cerebellar anatomy and function to solve the said problem. The proposed model is stable under all conditions merely by parameter determination, in contrast to recursive model-based solutions, which remain stable only under certain conditions. We modified the proposed model for the simple two-segmented arm to prove the feasibility of the model under a basic condition. A fuzzy neural network through its learning method was used to compute the parameters of the system. Simulation results show the practical feasibility and efficiency of the proposed model in robotics. The main advantage of the proposed model is its generalizability and potential use in any robot. PMID:26438095

  3. Observation of isoscalar multipole strengths in exotic doubly-magic 56Ni in inelastic α scattering in inverse kinematics

    NASA Astrophysics Data System (ADS)

    Bagchi, S.; Gibelin, J.; Harakeh, M. N.; Kalantar-Nayestanaki, N.; Achouri, N. L.; Akimune, H.; Bastin, B.; Boretzky, K.; Bouzomita, H.; Caamaño, M.; Càceres, L.; Damoy, S.; Delaunay, F.; Fernández-Domínguez, B.; Fujiwara, M.; Garg, U.; Grinyer, G. F.; Kamalou, O.; Khan, E.; Krasznahorkay, A.; Lhoutellier, G.; Libin, J. F.; Lukyanov, S.; Mazurek, K.; Najafi, M. A.; Pancin, J.; Penionzhkevich, Y.; Perrot, L.; Raabe, R.; Rigollet, C.; Roger, T.; Sambi, S.; Savajols, H.; Senoville, M.; Stodel, C.; Suen, L.; Thomas, J. C.; Vandebrouck, M.; Van de Walle, J.

    2015-12-01

    The Isoscalar Giant Monopole Resonance (ISGMR) and the Isoscalar Giant Dipole Resonance (ISGDR) compression modes have been studied in the doubly-magic unstable nucleus 56Ni. They were measured by inelastic α-particle scattering in inverse kinematics at 50 MeV/u with the MAYA active target at the GANIL facility. The centroid of the ISGMR has been obtained at Ex = 19.1 ± 0.5 MeV. Evidence for the low-lying part of the ISGDR has been found at Ex = 17.4 ± 0.7 MeV. The strength distribution for the dipole mode shows similarity with the prediction from the Hartree-Fock (HF) based random-phase approximation (RPA) [1]. These measurements confirm inelastic α-particle scattering as a suitable probe for exciting the ISGMR and the ISGDR modes in radioactive isotopes in inverse kinematics.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  5. Postseismic Deformation Following the 2010 El Mayor-Cucapah Earthquake: Observations, Kinematic Inversions, and Dynamic Models

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    Due to its location on a transtensional section of the Pacific-North American plate boundary, the Salton Trough is a region featuring large strike-slip earthquakes within a regime of shallow asthenosphere, high heat flow, and complex faulting, and so postseismic deformation there may feature enhanced viscoelastic relaxation and afterslip that is particularly detectable at the surface. The 2010 El Mayor-Cucapah earthquake was the largest shock in the Salton Trough since 1892 and occurred close to the US-Mexico border, and so the postseismic deformation recorded by the continuous GPS network of southern California provides an opportunity to study the rheology of this region. Three-year postseismic transients extracted from GPS displacement time-series show four key features: (1) 1-2 cm of cumulative uplift in the Imperial Valley and 1 cm of subsidence in the Peninsular Ranges, (2) relatively large cumulative horizontal displacements 150 km from the rupture in the Peninsular Ranges, (3) rapidly decaying horizontal displacement rates in the first few months after the earthquake in the Imperial Valley, and (4) sustained horizontal velocities, following the rapid early motions, that were still visibly ongoing 3 years after the earthquake. Kinematic inversions show that the cumulative 3-year postseismic displacement field can be well fit by afterslip on and below the coseismic rupture, though these solutions require afterslip with a total moment equivalent to at least a earthquake and higher slip magnitudes than those predicted by coseismic stress changes. Forward modeling shows that stress-driven afterslip and viscoelastic relaxation in various configurations within the lithosphere can reproduce the early and later horizontal velocities in the Imperial Valley, while Newtonian viscoelastic relaxation in the asthenosphere can reproduce the uplift in the Imperial Valley and the subsidence and large westward displacements in the Peninsular Ranges. We present two forward

  6. Probing the cluster structure of 7Li via elastic scattering on protons and deuterons in inverse kinematics

    NASA Astrophysics Data System (ADS)

    Pakou, A.; Soukeras, V.; Cappuzzello, F.; Acosta, L.; Agodi, C.; Aslanoglou, X.; Calabrese, S.; Carbone, D.; Cavallaro, M.; Foti, A.; Keeley, N.; Marquinez-Duran, G.; Martel, I.; Mazzocco, M.; Parascandolo, C.; Pierroutsakou, D.; Rusek, K.; Sgouros, O.; Strano, E.; Zagatto, V. A. B.

    2016-07-01

    Elastic scattering measurements were performed for the 7Li+p system in inverse kinematics at energies of 16, 25, 35, and 38.1 MeV and for the 7Li+d system at 38.1 MeV. The heavy ejectiles were detected by the large acceptance MAGNEX spectrometer at the Laboratori Nazionali del Sud in Catania, Italy. The results are analyzed using the Jeukenne-Lejeune-Mahaux and continuum discretized coupled channel frameworks. In the latter case the cluster structure of 7Li proves to be critical for the theoretical interpretation of the experimental results.

  7. Magnetic moment measurement in 72Zn using the Transient Field technique and Coulomb excitation in inverse kinematics

    NASA Astrophysics Data System (ADS)

    Illana Sisón, A.; Jungclaus, A.; Orlandi, R.; Perea, A.; Briz, J. A.; Bauer, C.; Gernhäuser, R.; Leske, J.; Mücher, D.; Pakarinen, J.; Pietralla, N.; Rajabali, M. M.; Seiler, D.; Stahl, C.

    2014-03-01

    The g factor of the first excited 2+ state of 72Zn has been measured using the Low Velocity Transient Field (LVTF) technique in combination with Coulomb excitation in inverse kinematics. The aim of the experiment was to test the viability of this method when applied to short-lived radioactive ISOL beams, in particular in comparison to the alternative High Velocity Transient Field (HVTF) technique using fragment beams. The result obtained for g(2+) in 72Zn in the present experiment follows the trend observed for the lighter stables Zn isotopes.

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

    USGS Publications Warehouse

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

    2005-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  10. The kinematic determinants of anuran swimming performance: an inverse and forward dynamics approach.

    PubMed

    Richards, Christopher T

    2008-10-01

    The aims of this study were to explore the hydrodynamic mechanism of Xenopus laevis swimming and to describe how hind limb kinematics shift to control swimming performance. Kinematics of the joints, feet and body were obtained from high speed video of X. laevis frogs (N=4) during swimming over a range of speeds. A blade element approach was used to estimate thrust produced by both translational and rotational components of foot velocity. Peak thrust from the feet ranged from 0.09 to 0.69 N across speeds ranging from 0.28 to 1.2 m s(-1). Among 23 swimming strokes, net thrust impulse from rotational foot motion was significantly higher than net translational thrust impulse, ranging from 6.1 to 29.3 N ms, compared with a range of -7.0 to 4.1 N ms from foot translation. Additionally, X. laevis kinematics were used as a basis for a forward dynamic anuran swimming model. Input joint kinematics were modulated to independently vary the magnitudes of foot translational and rotational velocity. Simulations predicted that maximum swimming velocity (among all of the kinematics patterns tested) requires that maximal translational and maximal rotational foot velocity act in phase. However, consistent with experimental kinematics, translational and rotational motion contributed unequally to total thrust. The simulation powered purely by foot translation reached a lower peak stroke velocity than the pure rotational case (0.38 vs 0.54 m s(-1)). In all simulations, thrust from the foot was positive for the first half of the power stroke, but negative for the second half. Pure translational foot motion caused greater negative thrust (70% of peak positive thrust) compared with pure rotational simulation (35% peak positive thrust) suggesting that translational motion is propulsive only in the early stages of joint extension. Later in the power stroke, thrust produced by foot rotation overcomes negative thrust (due to translation). Hydrodynamic analysis from X. laevis as well as forward

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    Research on the modeling of continuum robots, focused on ways to constrain the geometrical models, while maintaining maximum specificities and mechanical properties of the robot. In this paper we propose a new numerical solution for solving the inverse geometric model of a planar flexible continuum robot, we assuming that each section is curved in an arc of a circle, while having the central axis of the inextensible structure. The inverse geometric model for one section is calculated geometrically, whereas the extreme points, of each section, used in calculating the inverse geometric model for multi-section is calculated numerically using a particle swarm optimization (PSO) method. Simulation examples of this method are carried to validate the proposed approach.

  13. Kinematic inversion of strong motion data using a Gaussian parameterization of the slip: application to the Iwate-Miyagi earthquake.

    NASA Astrophysics Data System (ADS)

    Lucca, Ernestina; Festa, Gaetano; Emolo, Antonio

    2010-05-01

    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

  14. Study of 12C excited states decaying into three α particles using the thick target inverse kinematic technique

    NASA Astrophysics Data System (ADS)

    Barbui, M.; Hagel, K.; Gauthier, J.; Wuenschel, S.; de Souza, R. T.; Hudan, S.; Fang, D.; Goldberg, V. Z.; Zheng, H.; Giuliani, G.; Rapisarda, G.; Kim, E.-J.; Liu, X.; Natowitz, J. B.

    2016-05-01

    We will show that the Thick Target Inverse Kinematics (TTIK) technique can be used to investigate the breakup of excited selfconjugate nuclei into many alpha particles. Two test runs were performed at Cyclotron Institute of Texas A&M University to study the reaction 20Ne+α at maximum beam energies of 10 and 12 AMeV. Due to the limited statistics, only events with alpha multiplicity up to three were analyzed. The analysis of the three α-particle emission data allowed the identification of the Hoyle state and other 12C excited states decaying into three alpha particles. The results will be shown and compared with other data available in the literature.

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

    NASA Technical Reports Server (NTRS)

    Williams, Robert L., II

    1992-01-01

    The forward position and velocity kinematics for the redundant eight-degree-of-freedom Advanced Research Manipulator 2 (ARM2) are presented. Inverse position and velocity kinematic solutions are also presented. The approach in this paper is to specify two of the unknowns and solve for the remaining six unknowns. Two unknowns can be specified with two restrictions. First, the elbow joint angle and rate cannot be specified because they are known from the end-effector position and velocity. Second, one unknown must be specified from the four-jointed wrist, and the second from joints that translate the wrist, elbow joint excluded. There are eight solutions to the inverse position problem. The inverse velocity solution is unique, assuming the Jacobian matrix is not singular. A discussion of singularities is based on specifying two joint rates and analyzing the reduced Jacobian matrix. When this matrix is singular, the generalized inverse may be used as an alternate solution. Computer simulations were developed to verify the equations. Examples demonstrate agreement between forward and inverse solutions.

  16. Jacobian conditioning analysis for model validation.

    PubMed

    Rivals, Isabelle; Personnaz, Léon

    2004-02-01

    Our aim is to stress the importance of Jacobian matrix conditioning for model validation. We also comment on Monari and Dreyfus (2002), where, following Rivals and Personnaz (2000), it is proposed to discard neural candidates that are likely to overfit and/or for which quantities of interest such as confidence intervals cannot be computed accurately. In Rivals and Personnaz (2000), we argued that such models are to be discarded on the basis of the condition number of their Jacobian matrix. But Monari and Dreyfus (2002) suggest making the decision on the basis of the computed values of the leverages, the diagonal elements of the projection matrix on the range of the Jacobian, or "hat" matrix: they propose to discard a model if computed leverages are outside some theoretical bounds, pretending that it is the symptom of the Jacobian rank deficiency. We question this proposition because, theoretically, the hat matrix is defined whatever the rank of the Jacobian and because, in practice, the computed leverages of very ill-conditioned networks may respect their theoretical bounds while confidence intervals cannot be estimated accurately enough, two facts that have escaped Monari and Dreyfus's attention. Wealso recall the most accurate way to estimate the leverages and the properties of these estimations. Finally, we make an additional comment concerning the performance estimation in Monari and Dreyfus (2002). PMID:15006102

  17. Exploring clustering in alpha-conjugate nuclei using the thick target inverse kinematic technique for multiple alpha emission

    NASA Astrophysics Data System (ADS)

    Barbui, M.; Hagel, K.; Gauthier, J.; Wuenschel, S.; Goldberg, V. Z.; Zheng, H.; Giuliani, G.; Rapisarda, G.; Kim, E.-J.; Liu, X.; Natowitz, J. B.; Desouza, R. T.; Hudan, S.; Fang, D.

    2015-10-01

    Searching for alpha cluster states analogous to the 12C Hoyle state in heavier alpha-conjugate nuclei can provide tests of the existence of alpha condensates in nuclear matter. Such states are predicted for 16O, 20Ne, 24Mg, etc. at excitation energies slightly above the decay threshold. The Thick Target Inverse Kinematics (TTIK) technique can be successfully used to study the breakup of excited self-conjugate nuclei into many alpha particles. The reaction 20Ne + α at 11 and 13 AMeV was studied at Cyclotron Institute at Texas A&M University. Here the TTIK method was used to study both single α-particle emission and multiple α-particle decays. Due to the limited statistics, only events with alpha multiplicity up to three were analyzed. The analysis of the three α-particle emission data allowed the identification of the Hoyle state and other 12C excited states decaying into three alpha particles. The results will be shown and compared with other data available in the literature. Another experiment is planned in August 2015 to study the system 28Si + α at 15 AMeV. Preliminary results will be shown. Supported by the U.S. DOE and the Robert A. Welch Foundation, Grant No. A0330.

  18. Multi-GPU Jacobian Accelerated Computing for Soft Field Tomography

    PubMed Central

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

    2012-01-01

    Image reconstruction in soft-field tomography is based on an inverse problem formulation, where a forward model is fitted to the data. In medical applications, where the anatomy presents complex shapes, it is common to use Finite Element Models to represent the volume of interest and to solve a partial differential equation that models the physics of the system. Over the last decade, there has been a shifting interest from 2D modeling to 3D modeling, as the underlying physics of most problems are three-dimensional. Though the increased computational power of modern computers allows working with much larger FEM models, the computational time required to reconstruct 3D images on a fine 3D FEM model can be significant, on the order of hours. For example, in Electrical Impedance Tomography applications using a dense 3D FEM mesh with half a million elements, a single reconstruction iteration takes approximately 15 to 20 minutes with optimized routines running on a modern multi-core PC. It is desirable to accelerate image reconstruction to enable researchers to more easily and rapidly explore data and reconstruction parameters. Further, providing high-speed reconstructions are essential for some promising clinical application of EIT. For 3D problems 70% of the computing time is spent building the Jacobian matrix, and 25% of the time in forward solving. In the present work, we focus on accelerating the Jacobian computation by using single and multiple GPUs. First, we discuss an optimized implementation on a modern multi-core PC architecture and show how computing time is bounded by the CPU-to-memory bandwidth; this factor limits the rate at which data can be fetched by the CPU. Gains associated with use of multiple CPU cores are minimal, since data operands cannot be fetched fast enough to saturate the processing power of even a single CPU core. GPUs have a much faster memory bandwidths compared to CPUs and better parallelism. We are able to obtain acceleration factors of

  19. Inversions

    ERIC Educational Resources Information Center

    Brown, Malcolm

    2009-01-01

    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…

  20. Saccade control in a simulated robot camera-head system: neural net architectures for efficient learning of inverse kinematics.

    PubMed

    Dean, P; Mayhew, J E; Thacker, N; Langdon, P M

    1991-01-01

    The high speed of saccades means that they cannot be guided by visual feedback, so that any saccadic control system must know in advance the correct output signals to fixate a particular retinal position. To investigate neural-net architectures for learning this inverse-kinematics problem we simulated a 4 deg-of-freedom robot camera-head system, in which the head could pan and tilt and the cameras pan and verge. The main findings were: (1) Linear nets, multilayer perceptrons (MLPs) trained by backpropagation, and cerebellar model arithmetic computers (CMACs) all learnt rapidly to 5-10% accuracy when given perfect error feedback. (2) For additional accuracy (down to 2%) two-layer nets learnt much faster than a single MLP or CMAC: the best combination tried was to have a CMAC learn the errors of a trained linear net. (3) Imperfect error signals were provided by a crude controller whose output was simply proportional to retinal input in the relevant axis, thereby providing a mechanism for (a) controlling the camera-head system when the feedforward neural net controller was wrong or inoperative, and (b) converting sensory error signals into motor error signals as required in supervised learning. It proved possible to train neural-net controllers using these imperfect error signals over a range of learning rates and crude-controller gains. These results suggest that appropriate neural-net architectures can provide practical, accurate and robust adaptive control for saccadic movements. In addition, the arrangement of a crude controller teaching a sophisticated one may be similar to that used by the primate saccadic system, with brainstem circuitry teaching the cerebellum.

  1. A Jacobian elliptic single-field inflation

    NASA Astrophysics Data System (ADS)

    Villanueva, J. R.; Gallo, Emanuel

    2015-06-01

    In the scenario of single-field inflation, this field is described in terms of Jacobian elliptic functions. This approach provides, when constrained to particular cases, analytic solutions already known in the past, generalizing them to a bigger family of analytical solutions. The emergent cosmology is analyzed using the Hamilton-Jacobi approach and then the main results are contrasted with the recent measurements obtained from the Planck 2015 data.

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

    NASA Astrophysics Data System (ADS)

    Ruiz, S.; Madariaga, R.

    2012-04-01

    The Maule 2010 Mw 8.8 Chile and Tohoku 2011 Mw 9.0 earthquakes were recorded by continuous GPS (cGPS) and Strong Motion (SM) instruments, with good resolution at low and high frequencies, respectively. The dual behavior of low and high frequencies during large earthquakes is an important issue in seismic hazard because the highest seismic intensities are associated mainly with high frequency waves, while low frequency waves are associated with tsunami generation and the largest coseismic displacements. Previous works proposed that most of the low frequency waves were generated in the shallow part of the contact, while that high frequency waves were released in the deeper zone of the plate interface. We made kinematic inversions in different frequency bands using cGPS and SM to study the seismic ruptures and their frequency behavior. The AXITRA spectral code was used to simulate wave propagation in a flat layered medium. We used two approaches to model the source: elliptical patches and fixed rectangular mesh. Both models fit more than 90% of the variance. Our inversions for Tohoku earthquake show low frequency energy released in the shallow part of the interface and high frequency release in its deeper part, similar to findings in previous works. For Maule, on the other hand, we propose that the main high frequency source was located in the northern part of the rupture, not necessarily in the deeper contact zone that could not be broken during this earthquake. We think that high frequency is concentrated in the boundaries of the rupture caused by the arrest of the rupture propagation. The Maule rupture had a direction of propagation mainly from south to north generating a concentration of high frequency waves in small zones of the northern edge of the rupture. The Tohoku earthquake had a direction of propagation mainly from shallow depth to the deeper part of the plate interface generating more high frequency waves in small zones of the deeper edges. The Maule 2010

  3. Adaptive Jacobian Fuzzy Attitude Control for Flexible Spacecraft Combined Attitude and Sun Tracking System

    NASA Astrophysics Data System (ADS)

    Chak, Yew-Chung; Varatharajoo, Renuganth

    2016-07-01

    Many spacecraft attitude control systems today use reaction wheels to deliver precise torques to achieve three-axis attitude stabilization. However, irrecoverable mechanical failure of reaction wheels could potentially lead to mission interruption or total loss. The electrically-powered Solar Array Drive Assemblies (SADA) are usually installed in the pitch axis which rotate the solar arrays to track the Sun, can produce torques to compensate for the pitch-axis wheel failure. In addition, the attitude control of a flexible spacecraft poses a difficult problem. These difficulties include the strong nonlinear coupled dynamics between the rigid hub and flexible solar arrays, and the imprecisely known system parameters, such as inertia matrix, damping ratios, and flexible mode frequencies. In order to overcome these drawbacks, the adaptive Jacobian tracking fuzzy control is proposed for the combined attitude and sun-tracking control problem of a flexible spacecraft during attitude maneuvers in this work. For the adaptation of kinematic and dynamic uncertainties, the proposed scheme uses an adaptive sliding vector based on estimated attitude velocity via approximate Jacobian matrix. The unknown nonlinearities are approximated by deriving the fuzzy models with a set of linguistic If-Then rules using the idea of sector nonlinearity and local approximation in fuzzy partition spaces. The uncertain parameters of the estimated nonlinearities and the Jacobian matrix are being adjusted online by an adaptive law to realize feedback control. The attitude of the spacecraft can be directly controlled with the Jacobian feedback control when the attitude pointing trajectory is designed with respect to the spacecraft coordinate frame itself. A significant feature of this work is that the proposed adaptive Jacobian tracking scheme will result in not only the convergence of angular position and angular velocity tracking errors, but also the convergence of estimated angular velocity to

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

    SciTech Connect

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

    2005-08-01

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

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

    PubMed

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

    2012-05-01

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

  6. The application of striation analysis and focal mechanism stress inversion in deducing the kinematic history of faults: Examples from the Bristol Channel UK and the Ionian Zone Greece

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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

  7. The 8Li + 2H reaction studied in inverse kinematics at 3.15 MeV/nucleon using the REX-ISOLDE post-accelerator

    NASA Astrophysics Data System (ADS)

    Tengborn, E.; Moro, A. M.; Nilsson, T.; Alcorta, M.; Borge, M. J. G.; Cederkäll, J.; Diget, C.; Fraile, L. M.; Fynbo, H. O. U.; Gomez-Camacho, J.; Jeppesen, H. B.; Johansson, H. T.; Jonson, B.; Kirsebom, O. S.; Knudsen, H. H.; Madurga, M.; Nyman, G.; Richter, A.; Riisager, K.; Schrieder, G.; Tengblad, O.; Timofeyuk, N.; Turrion, M.; Voulot, D.; Wenander, F.

    2011-12-01

    The reaction 8Li + 2H has been studied in inverse kinematics at the incident energy of 3.15 MeV/nucleon, using the REX-ISOLDE post-accelerator. The reaction channels corresponding to (d,p), (d,d), and (d,t) reactions populating ground states and low-lying excited states in 7-9Li have been identified and the related angular distributions extracted and compared with coupled-channels, distorted-wave Born approximation (DWBA), and coupled-reaction-channels calculations. For the inelastic and (d,t) channels we find that higher order effects are very important and hence one needs to go beyond the simple DWBA to extract reliable structure information from these processes.

  8. Lifetime measurement of candidate chiral doublet bands in the {sup 103, 104}Rh isotopes with the RDDS method in inverse kinematics.

    SciTech Connect

    Suzuki, T.; Rainovski, G.; Koike, T.; Ahn, T.; Carpenter, M. P.; Costin, A.; Danchev, M.; Dewald, A.; Janssens, R. V. F.; Joshi, P.; Lister, C. J.; Moller, A.; Pietralla, N.; Shinozuka, T.; Timar, J.; Wadsworth, R.; Vaman, C.; Zhu, S.; Physics; Tohoku Univ.; Univ. of Sofia; State Univ. of New York; Univ. of Tennessee; Univ. zu Koln; Univ. of York; TU Darmstadt; ATOMKI, Hungary; Michigan State Univ.

    2008-01-01

    Lifetimes of chiral candidate structures in {sup 103,104}Rh were measured using the recoil distance Doppler-shift method. The Gammasphere detector array was used in conjunction with the Cologne plunger device. Excited states of {sup 103,104}Rh were populated by the {sup 11}B({sup 96}Zr,4n){sup 103}Rh and {sup 11}B({sup 96}Zr,3n){sup 104}Rh fusion-evaporation reactions in inverse kinematics. Three and five lifetimes of levels belonging to the proposed chiral doublet bands are measured in {sup 103}Rh and {sup 104}Rh, respectively. The previously observed even-odd spin dependence of the B(M1)/B(E2) values is caused by the variation in the B(E2) values, whereas the B(M1) values decrease as a function of spin.

  9. Lifetime measurement of candidate chiral doublet bands in the {sup 103,104}Rh isotopes with the recoil-distance Doppler-shift method in inverse kinematics

    SciTech Connect

    Suzuki, T.; Rainovski, G.; Koike, T.; Ahn, T.; Costin, A.; Carpenter, M. P.; Janssens, R. V. F.; Lister, C. J.; Zhu, S.; Danchev, M.; Dewald, A.; Joshi, P.; Wadsworth, R.; Moeller, O.; Pietralla, N.; Shinozuka, T.; Timar, J.; Vaman, C.

    2008-09-15

    Lifetimes of chiral candidate structures in {sup 103,104}Rh were measured using the recoil distance Doppler-shift method. The Gammasphere detector array was used in conjunction with the Cologne plunger device. Excited states of {sup 103,104}Rh were populated by the {sup 11}B({sup 96}Zr,4n){sup 103}Rh and {sup 11}B({sup 96}Zr,3n){sup 104}Rh fusion-evaporation reactions in inverse kinematics. Three and five lifetimes of levels belonging to the proposed chiral doublet bands are measured in {sup 103}Rh and {sup 104}Rh, respectively. The previously observed even-odd spin dependence of the B(M1)/B(E2) values is caused by the variation in the B(E2) values, whereas the B(M1) values decrease as a function of spin.

  10. "Phoswich Wall": A charged-particle detector array for inverse-kinematic reactions with the Gretina/GRETA γ-ray arrays

    NASA Astrophysics Data System (ADS)

    Sarantites, D. G.; Reviol, W.; Elson, J. M.; Kinnison, J. E.; Izzo, C. J.; Manfredi, J.; Liu, J.; Jung, H. S.; Goerres, J.

    2015-08-01

    A high-efficiency, forward-hemisphere detector system for light charged particles and low-Z heavy ions, as obtained in an accelerator experiment, is described. It consists of four 8×8 pixel multianode photomultiplier tubes with 2.2-mm thick CsI(Tl) and 12 -μm thick fast-plastic scintillation detectors. Its phoswich structure allows individual Z resolution for 1H, 4He, 7Li, 4He+4He, 9Be, 11B, 12C, and 14N ions, which are target-like fragments detected in strongly inverse kinematics. The device design has been optimized for use with a 4π γ-ray array, and the main applications are transfer reactions and Coulomb excitation. A high-angular resolution for the detection of the target-like fragments is achieved which permits angular distributions to be measured in the rest frame of the projectile-like fragment with a resolution of ~ 2 °.

  11. Learning the inverse kinetics of an octopus-like manipulator in three-dimensional space.

    PubMed

    Giorelli, M; Renda, F; Calisti, M; Arienti, A; Ferri, G; Laschi, C

    2015-06-01

    This work addresses the inverse kinematics problem of a bioinspired octopus-like manipulator moving in three-dimensional space. The bioinspired manipulator has a conical soft structure that confers the ability of twirling around objects as a real octopus arm does. Despite the simple design, the soft conical shape manipulator driven by cables is described by nonlinear differential equations, which are difficult to solve analytically. Since exact solutions of the equations are not available, the Jacobian matrix cannot be calculated analytically and the classical iterative methods cannot be used. To overcome the intrinsic problems of methods based on the Jacobian matrix, this paper proposes a neural network learning the inverse kinematics of a soft octopus-like manipulator driven by cables. After the learning phase, a feed-forward neural network is able to represent the relation between manipulator tip positions and forces applied to the cables. Experimental results show that a desired tip position can be achieved in a short time, since heavy computations are avoided, with a degree of accuracy of 8% relative average error with respect to the total arm length. PMID:25970238

  12. Learning the inverse kinetics of an octopus-like manipulator in three-dimensional space.

    PubMed

    Giorelli, M; Renda, F; Calisti, M; Arienti, A; Ferri, G; Laschi, C

    2015-05-13

    This work addresses the inverse kinematics problem of a bioinspired octopus-like manipulator moving in three-dimensional space. The bioinspired manipulator has a conical soft structure that confers the ability of twirling around objects as a real octopus arm does. Despite the simple design, the soft conical shape manipulator driven by cables is described by nonlinear differential equations, which are difficult to solve analytically. Since exact solutions of the equations are not available, the Jacobian matrix cannot be calculated analytically and the classical iterative methods cannot be used. To overcome the intrinsic problems of methods based on the Jacobian matrix, this paper proposes a neural network learning the inverse kinematics of a soft octopus-like manipulator driven by cables. After the learning phase, a feed-forward neural network is able to represent the relation between manipulator tip positions and forces applied to the cables. Experimental results show that a desired tip position can be achieved in a short time, since heavy computations are avoided, with a degree of accuracy of 8% relative average error with respect to the total arm length.

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

    SciTech Connect

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

    1997-01-01

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

  14. The jumping mechanism of cicada Cercopis vulnerata (Auchenorrhyncha, Cercopidae): skeleton-muscle organisation, frictional surfaces, and inverse-kinematic model of leg movements.

    PubMed

    Gorb, Stanislav N

    2004-07-01

    In Auchenorrhyncha, jumping is achieved by metathoracic muscles which are inserted into the trochanter of the hind leg. The synchronisation of movements of the hind legs is a difficult problem, as the leg extension that produces the jump occurs in less than 1 ms. Even slight asynchrony could potentially result in failure of a jump. Both the synchronisation of the movements of a pair of jumping legs, and their stabilisation during a jump, seem to be important problems for small jumping insects. The present study was performed in order to clarify some questions of the functional morphology of the leafhopper jumping mechanism. It is based on skeleton-muscle reconstruction, high-speed video recordings, transmission (TEM) and scanning electron microscopic (SEM) investigations of the cuticle, together with 3D inverse-kinematic modelling of angles and working zones of hind leg joints of cicada Cercopis vulnerata (Cercopidae). The complete extension of the hind leg takes less than 1 ms, which suggests that the jump is powered not only by the muscle system, but also by an elastic spring. Histological staining and fluorescence microscopy showed resilin-bearing structures, responsible for elastic energy storage, in the pleural area of the metathorax. Synchronisation of hind leg movements may be aided by microtrichia fields that are located on the medial surface of each hind coxa. In Auchenorrhyncha, hind coxae are rounded in their anterior and lateral parts, whereas medial parts are planar, and contact each other over a rather large area. The inverse-kinematic model of propulsive leg movements was used to draw the surface outlined by the medial surface of the coxa, during the jump movement. This is a cone surface, faced with its bulged-in side, medially. Surfaces outlined by the movements of both right and left coxae overlap in their anterior and posterior positions. In both extreme positions, coxae are presumably connected to each other by coupled microtrichia fields. Thus

  15. Off-diagonal Jacobian support for Nodal BCs

    SciTech Connect

    Peterson, John W.; Andrs, David; Gaston, Derek R.; Permann, Cody J.; Slaughter, Andrew E.

    2015-01-01

    In this brief note, we describe the implementation of o-diagonal Jacobian computations for nodal boundary conditions in the Multiphysics Object Oriented Simulation Environment (MOOSE) [1] framework. There are presently a number of applications [2{5] based on the MOOSE framework that solve complicated physical systems of partial dierential equations whose boundary conditions are often highly nonlinear. Accurately computing the on- and o-diagonal Jacobian and preconditioner entries associated to these constraints is crucial for enabling ecient numerical solvers in these applications. Two key ingredients are required for properly specifying the Jacobian contributions of nonlinear nodal boundary conditions in MOOSE and nite element codes in general: 1. The ability to zero out entire Jacobian matrix rows after \

  16. Jurassic extension and Cenozoic inversion tectonics in the Asturian Basin, NW Iberian Peninsula: 3D structural model and kinematic evolution

    NASA Astrophysics Data System (ADS)

    Uzkeda, Hodei; Bulnes, Mayte; Poblet, Josep; García-Ramos, José Carlos; Piñuela, Laura

    2016-09-01

    We constructed a geological map, a 3D model and cross-sections, carried out a structural analysis, determined the stress fields and tectonic transport vectors, restored a cross section and performed a subsidence analysis to unravel the kinematic evolution of the NE emerged portion of the Asturian Basin (NW Iberian Peninsula), where Jurassic rocks crop out. The major folds run NW-SE, normal faults exhibit three dominant orientations: NW-SE, NE-SW and E-W, and thrusts display E-W strikes. After Upper Triassic-Lower Jurassic thermal subsidence, Middle Jurassic doming occurred, accompanied by normal faulting, high heat flow and basin uplift, followed by Upper Jurassic high-rate basin subsidence. Another extensional event, possibly during Late Jurassic-Early Cretaceous, caused an increment in the normal faults displacement. A contractional event, probably of Cenozoic age, led to selective and irregularly distributed buttressing and fault reactivation as reverse or strike-slip faults, and folding and/or offset of some previous faults by new generation folds and thrusts. The Middle Jurassic event could be a precursor of the Bay of Biscay and North Atlantic opening that occurred from Late Jurassic to Early Cretaceous, whereas the Cenozoic event would be responsible for the Pyrenean and Cantabrian ranges and the partial closure of the Bay of Biscay.

  17. Differential Kinematics Of Contemporary Industrial Robots

    NASA Astrophysics Data System (ADS)

    Szkodny, T.

    2014-08-01

    The paper presents a simple method of avoiding singular configurations of contemporary industrial robot manipulators of such renowned companies as ABB, Fanuc, Mitsubishi, Adept, Kawasaki, COMAU and KUKA. To determine the singular configurations of these manipulators a global form of description of the end-effector kinematics was prepared, relative to the other links. On the basis of this description , the formula for the Jacobian was defined in the end-effector coordinates. Next, a closed form of the determinant of the Jacobian was derived. From the formula, singular configurations, where the determinant's value equals zero, were determined. Additionally, geometric interpretations of these configurations were given and they were illustrated. For the exemplary manipulator, small corrections of joint variables preventing the reduction of the Jacobian order were suggested. An analysis of positional errors, caused by these corrections, was presented

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

    USGS Publications Warehouse

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

    2007-01-01

    We present a two-stage nonlinear technique to invert strong motions records and geodetic data to retrieve the rupture history of an earthquake on a finite fault. To account for the actual rupture complexity, the fault parameters are spatially variable peak slip velocity, slip direction, rupture time and risetime. The unknown parameters are given at the nodes of the subfaults, whereas the parameters within a subfault are allowed to vary through a bilinear interpolation of the nodal values. The forward modeling is performed with a discrete wave number technique, whose Green's functions include the complete response of the vertically varying Earth structure. During the first stage, an algorithm based on the heat-bath simulated annealing generates an ensemble of models that efficiently sample the good data-fitting regions of parameter space. In the second stage (appraisal), the algorithm performs a statistical analysis of the model ensemble and computes a weighted mean model and its standard deviation. This technique, rather than simply looking at the best model, extracts the most stable features of the earthquake rupture that are consistent with the data and gives an estimate of the variability of each model parameter. We present some synthetic tests to show the effectiveness of the method and its robustness to uncertainty of the adopted crustal model. Finally, we apply this inverse technique to the well recorded 2000 western Tottori, Japan, earthquake (Mw 6.6); we confirm that the rupture process is characterized by large slip (3-4 m) at very shallow depths but, differently from previous studies, we imaged a new slip patch (2-2.5 m) located deeper, between 14 and 18 km depth. Copyright 2007 by the American Geophysical Union.

  19. Finite fault kinematic inversion of the 2012, May 20th and 29th Emilia-Romagna, Northern Italy, Earthquakes.

    NASA Astrophysics Data System (ADS)

    Cirella, A.; Piatanesi, A.; Molinari, I.

    2015-12-01

    In this study, we investigate the rupture process of the 2012, May 20 and 29, Mw 6.1 and 5.9, respectively, Emilia-Romagna, Northern Italy, earthquakes. The two earthquakes struck a densely populated region, causing 26 fatalities and significantly damaging the economy of the region. We image the rupture history of these events, by separately and jointly inverting strong motions, GPS displacements and High-Rate GPS data. The region of interest is a sedimentary basin (the Po Plain) surrounded by the northern Apennines; and it is characterized by a significant presence of fluid and strong heterogeneities leading to remarkable site effects and liquefaction phenomena; for these reasons we adopt an ad-hoc velocity profiles at each station, by inverting in a low-intermediate frequency band (0 - 0.25 Hz). We use a two-stage non-linear inversion technique that, 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. 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 the algorithm performs a statistical analysis of the ensemble providing us the best-fitting model, the average model, and the associated standard deviation, coefficient of variation, moda and median distributions. The goal of our work is to constrain the earthquake rupture history and to assess the associated model uncertainty, to better understand the mechanics of the causative fault as well as the observed ground shaking.

  20. Rapid kinematic finite-fault inversion for an Mw 7+ scenario earthquake in the Marmara Sea: an uncertainty study

    NASA Astrophysics Data System (ADS)

    Diao, Faqi; Wang, Rongjiang; Aochi, Hideo; Walter, Thomas R.; Zhang, Yong; Zheng, Yong; Xiong, Xiong

    2016-02-01

    During the 20th century, a series of devastating earthquakes occurred along the North Anatolian Fault. These generally propagated westwards, such that the main fault segment beneath the Marmara Sea appears as a seismic gap. For the nearby megacity Istanbul, rapid seismic hazard assessment is currently of great importance. A key issue is how a strong earthquake in the Marmara Sea can be characterized reliably and rapidly using the seismic network currently operating in this region. In order to investigate this issue, several scenario earthquakes on the main Marmara fault are simulated through dynamic modelling based on a 3-D structure model. The synthetic datasets are then used to reconstruct the source processes of the causal events with a recently developed iterative deconvolution and stacking method based on simplified 1-D Earth structure models. The results indicate that, by using certain a priori information about the fault geometry and focal mechanism, the tempo-spatial slip patterns of the input scenarios can be well resolved. If reasonable uncertainties are considered for the a priori information, the key source parameters, such as moment magnitude, fault size and slip centroid, can still be estimated reliably, while the detailed tempo-spatial rupture pattern may reveal significant variations. To reduce the effect induced by employing the inaccurate event location and focal mechanism, a new approach for absolute source imaging is proposed and tested. We also investigate the performance of the new source imaging tool for near real-time source inversion under the current network configuration in the Marmara Sea region. The results obtained are meaningful particularly for developing the rapid earthquake response system for the megacity Istanbul.

  1. Rapid kinematic finite-fault inversion for an Mw 7+ scenario earthquake in the Marmara Sea: an uncertainty study

    NASA Astrophysics Data System (ADS)

    Diao, Faqi; Wang, Rongjiang; Aochi, Hideo; Zhang, Yong; Walter, Thomas R.

    2016-04-01

    During the last century, the North Anatolian Fault (NAF) generated a series of devastating earthquakes, which generally propagated westwards, such that the main Marmara fault segment as a seismic gap. For the nearby megacity Istanbul, rapid seismic hazard assessment is currently of great importance. A key issue is how a strong earthquake in the Marmara Sea can be characterized reliably and rapidly using the seismic network currently operating in this region. In the frame of the MARsite project, several scenario earthquakes on the main Marmara fault are simulated through dynamic modelling based on a 3-D structure model. The synthetic datasets are then used to reconstruct the source processes of the causal events with a recently developed iterative deconvolution and stacking method based on simplified 1-D Earth structure models. The results indicate that, by using certain a priori information about the fault geometry and focal mechanism, the tempo-spatial slip patterns of the input scenarios can be well resolved robustly. If reasonable uncertainties are considered for the a priori information, the key source parameters, such as moment magnitude, fault size and slip centroid, can still be estimated robustly, while the detailed tempo-spatial rupture pattern may reveal significant variations. To reduce the effect induced by employing the inaccurate event location and focal mechanism, a new approach for absolute source imaging is proposed and tested for near real-time source inversion under the current network configuration in the Marmara Sea region. The results obtained are meaningful particularly for developing the rapid earthquake response system for the megacity Istanbul.

  2. A Study of Primary Collision Dynamics in Inverse-Kinematics Reaction of 78Kr on 40Ca at a Bombarding Energy of 10 MeV per Nucleon

    NASA Astrophysics Data System (ADS)

    Henry, Eric M.

    The CHIMERA multi-detector array at LNS Catania has been used to study the inverse-kinematics reaction of 78Kr + 40Ca at a bombarding energy of 10 A MeV. The multi-detector is capable of detecting individual products of the collision essential for the reconstruction of the collision dynamics. This is the first time CHIMERA has been used at low-energy, which offered a unique challenge for the calibration and interpretation of experimental data. Initial interrogation of the calibrated data revealed a class of selected events characterized by two coincident heavy fragments (atomic number Z>3) that together account for the majority of the total mass of the colliding system. These events are consistent with the complete fusion and subsequent binary split (fission) of a composite nucleus. The observed fission fragments are characterized by a broad A, Z distribution and are centered about symmetric fission while exhibiting relative velocities significantly higher than given by Viola systematics. Additional analysis of the kinematic relationship between the fission fragments was performed. Of note, is that the center-of-mass angular distribution (dsigma/dtheta) of the fission fragments exhibits an unexpected anisotropy inconsistent with a compound-nucleus reaction. This anisotropy is indicative of a dynamic fusion/fission-like process. The observed angular distribution features a forward-backward anisotropy most prevalent for mass-asymmetric events. Furthermore, the more massive fragment of mass-asymmetric events appears to emerge preferentially in the forward direction, along the beam axis. Analysis of the angular distribution of alpha particles emitted from these fission fragments suggests the events are associated mostly with central collisions. The observations associated with this subset of events are similar to those reported for dynamic fragmentation of projectile-like fragments, but have not before been observed for a fusion/fission-like process. Comparisons to

  3. Force-free Jacobian equilibria for Vlasov-Maxwell plasmas

    SciTech Connect

    Abraham-Shrauner, B.

    2013-10-15

    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.

  4. The Matrix Editor for symbolic Jacobians in ALPAL

    SciTech Connect

    Painter, J.F.

    1991-12-01

    ALPAL is a Macsyma-based tool that automatically generates code to solve nonlinear integro-differential equations, given a very high-level specification of the equations to be solved and the numerical methods to be used. The Matrix Editor is a graphical, interactive tool for specifying the handling of Jacobian matrices and linear solvers. It automates such routine but difficult tasks as correctly converting from the data structures used for computing the Jacobian to data structures used by a linear solver. The user specifies what to do only at a high, natural level of abstraction.

  5. Source rupture processes of the foreshock and mainshock in the 2016 Kumamoto earthquake sequence estimated from the kinematic waveform inversion of strong motion data

    NASA Astrophysics Data System (ADS)

    Asano, Kimiyuki; Iwata, Tomotaka

    2016-08-01

    The 2016 Kumamoto earthquake sequence started with an MJMA 6.5 foreshock occurring along the northern part of the Hinagu fault, central Kyushu, Japan, and the MJMA 7.3 mainshock occurred just 28 h after the foreshock. We analyzed the source rupture processes of the foreshock and mainshock by using the kinematic waveform inversion technique on strong motion data. The foreshock was characterized by right-lateral strike-slip occurring on a nearly vertical fault plane along the northern part of the Hinagu fault, and it had two large-slip areas: one near the hypocenter and another at a shallow depth. The rupture of the mainshock started from the deep portion of a northwest-dipping fault plane along the northern part of the Hinagu fault, then continued to transfer to the Futagawa fault. Most of the significant slip occurred on the Futagawa fault, and the shallow portion of the Hinagu fault also had a relatively large slip. The slip amount on the shallowest subfaults along the Futagawa fault was approximately 1-4 m, which is consistent with the emergence of surface breaks associated with this earthquake. Right-lateral strike-slip dominated on the fault segment along the Hinagu fault, but normal-slip components were estimated to make a significant contribution on the fault segment along the Futagawa fault. The large fault-parallel displacements recorded at two near-fault strong motion stations coincided with the spatiotemporal pattern of the fault slip history during the mainshock. The spatial relationship between the rupture areas of the foreshock and mainshock implies a complex fault structure in this region.

  6. On the equivariant algebraic Jacobian for curves of genus two

    NASA Astrophysics Data System (ADS)

    Athorne, Chris

    2012-04-01

    We present a treatment of the algebraic description of the Jacobian of a generic genus two plane curve which exploits an SL2(k) equivariance and clarifies the structure of Flynn's 72 defining quadratic relations. The treatment is also applied to the Kummer variety.

  7. Exploring Strange Nonchaotic Attractors through Jacobian Elliptic Functions

    ERIC Educational Resources Information Center

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

    2011-01-01

    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…

  8. Generic robotic kinematic generator for virtual environment interfaces

    NASA Astrophysics Data System (ADS)

    Flueckiger, Lorenzo; Piguet, Laurent; Baur, Charles

    1996-12-01

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

  9. Analytical Jacobian Calculation in RT Model Including Polarization Effect

    NASA Astrophysics Data System (ADS)

    Okabayashi, Y.; Yoshida, Y.; Ota, Y.

    2014-12-01

    The greenhouse gas observing satellite "GOSAT" launched in January 2009 has been observing global distribution of CO2 and CH4. The TANSO-FTS mounted on GOSAT measures the two polarized components (called "P" and "S") of short wavelength infrared (SWIR) spectrum reflected from the earth's surface. In NIES, column-averaged dry air mole fraction of CO2 and CH4 (XCO2 and XCH4) are retrieved from SWIR spectra. However, the observed polarization information is not effectively utilized in the retrieval process due to the large computational cost of a vector RT model, instead the polarization synthesized spectra and a scalar RT model are used in the operational processing. An optical path length modification due to aerosol scattering is known as the major error source for XCO2 and XCH4 retrieval from SWIR spectra. Because the aerosol scattering changes polarization state of light, more accurate or additional aerosol information is expected by using the observed polarization spectra effectively in the retrieval process, which improves the retrieval accuracy of XCO2 and XCH4. In addition, for information content analysis, sensitivity analysis and error analysis, Jacobian matrix is important onto retrieval algorithm design before analyses for actual observed data. However, in the case of using RT model including polarization effect in retrieval process, the computational cost of Jacobian matrix calculations in maximum a posteriori retrieval is significantly large. Efficient calculation of analytical Jacobian is necessary. As a first step, we are implementing an analytical Jacobian calculation function to the vector RT model "Pstar". RT scheme of Pstar is based on hybrid method comprising the discrete ordinate and matrix operator methods. The reflection/transmission matrices and source vectors are obtained for each vertical layer through the discrete ordinate solution, and the vertically inhomogeneous system is constructed using the matrix operator method. Because the delta

  10. Inversion strategies for visco-acoustic waveform inversion

    NASA Astrophysics Data System (ADS)

    Kamei, R.; Pratt, R. G.

    2013-08-01

    Visco-acoustic waveform inversion can potentially yield quantitative images of the distribution of both velocity and the attenuation parameters from seismic data. Intrinsic P-wave attenuation has been of particular interest, but has also proven challenging. Frequency-domain inversion allows attenuation and velocity relations to be easily incorporated, and allows a natural multiscale approach. The Laplace-Fourier approach extends this to allow the natural damping of waveforms to enhance early arrivals. Nevertheless, simultaneous inversion of velocity and attenuation leads to significant `cross-talk' between the resulting images, reflecting a lack of parameter resolution and indicating the need for pre-conditioning and regularization of the inverse problem. We analyse the cross-talk issue by partitioning the inversion parameters into two classes; the velocity parameter class, and the attenuation parameter class. Both parameters are defined at a reference frequency, and a dispersion relation is assumed that describes these parameters at any other frequency. We formulate the model gradients at a forward modelling frequency, and convert them to the reference frequency by employing the Jacobian of the coordinate change represented by the dispersion relation. We show that at a given modelling frequency, the Fréchet derivatives corresponding to these two parameter classes differ only by a 90° phase shift, meaning that the magnitudes of resulting model updates will be unscaled, and will not reflect the expected magnitudes in realistic (Q-1 ≪ 1) media. Due to the lack of scaling, cross-talk will be enhanced by poor subsurface illumination, by errors in kinematics, and by data noise. To solve these issues, we introduce an attenuation scaling term (the inverse of a penalty term) that is used to pre-condition the gradient by controlling the magnitudes of the updates to the attenuation parameters. Initial results from a suite of synthetic cross-hole tests using a three

  11. A Parallel, Fully Coupled, Fully Implicit Solution to Reactive Transport in Porous Media Using the Preconditioned Jacobian-Free Newton-Krylov Method

    SciTech Connect

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

    2013-03-01

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

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

    SciTech Connect

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

    2012-06-01

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

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

    PubMed

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

    2013-07-01

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

  14. Low-rank Quasi-Newton updates for Robust Jacobian lagging in Newton methods

    SciTech Connect

    Brown, J.; Brune, P.

    2013-07-01

    Newton-Krylov methods are standard tools for solving nonlinear problems. A common approach is to 'lag' the Jacobian when assembly or preconditioner setup is computationally expensive, in exchange for some degradation in the convergence rate and robustness. We show that this degradation may be partially mitigated by using the lagged Jacobian as an initial operator in a quasi-Newton method, which applies unassembled low-rank updates to the Jacobian until the next full reassembly. We demonstrate the effectiveness of this technique on problems in glaciology and elasticity. (authors)

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

    SciTech Connect

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

    2012-06-01

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

  16. The 2014 Pisagua-Iquique earthquakes: high-resolution kinematic source models by joint inversion of the strong-motion and GPS data

    NASA Astrophysics Data System (ADS)

    Wang, Rongjiang; Zhang, Yong; Schurr, Bernd; Dahm, Torsten

    2016-04-01

    By combining the complementary advantages of conventional inversion and back-projection methods, we have developed an iterative deconvolution and stacking (IDS) approach for imaging earthquake rupture processes with near-field complete waveform data. This new approach does not need any manual adjustment of the physical (empirical) constraints, such as restricting the rupture time and duration, smoothing the spatiotemporal slip distribution, etc., and therefore has the ability to image complex multiple ruptures automatically. A high-resolution (ca.  10 km) source imaging is achieved for the 2014 Pisagua-Iquique earthquakes by applying the IDS approach to the regional strong-motion and GPS data jointly. It reveals more physical insights into the rupture process. For such large earthquakes, there exists generally a clear rupture front propagating with a finite velocity, but no clear healing front following the rupture front, implying that single rupturing is special, multiple rupturing is general. Each of the two earthquakes consists of several major sub-events and numerous coseismic early aftershocks, which can trigger each other statically and/or dynamically. The peak fault slip is generally not formed by a single rise-time, but through a cumulative process that can last as long as the whole earthquake duration. The rupture plane of large earthquakes might not be a simple smooth surface, but a rough surface or even a rupture zone with certain thickness (a few km?) consistent with the aftershock clustering around the fault.

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

    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

  18. Fault structure and kinematics of the Long Valley Caldera region, California, revealed by high-accuracy earthquake hypocenters and focal mechanism stress inversions

    USGS Publications Warehouse

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

    2002-01-01

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

  19. Jacobian integration method increases the statistical power to measure gray matter atrophy in multiple sclerosis☆

    PubMed Central

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

    2013-01-01

    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. PMID:24266007

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

    NASA Technical Reports Server (NTRS)

    Williams, Robert L., II

    1991-01-01

    Presented here are kinematic equations for a six degree of freedom force-reflecting hand controller. The forward kinematics solution is developed and shown in simplified form. The Jacobian matrix, which uses terms from the forward kinematics solution, is derived. Both of these kinematic solutions require joint angle inputs. A calibration method is presented to determine the hand controller joint angles given the respective potentiometer readings. The kinematic relationship describing the mechanical coupling between the hand and controller shoulder and elbow joints is given. These kinematic equations may be used in an algorithm to control the hand controller as a telerobotic system component. The purpose of the hand controller is two-fold: operator commands to the telerobotic system are entered using the hand controller, and contact forces and moments from the task are reflected to the operator via the hand controller.

  1. Laterally constrained inversion for CSAMT data interpretation

    NASA Astrophysics Data System (ADS)

    Wang, Ruo; Yin, Changchun; Wang, Miaoyue; Di, Qingyun

    2015-10-01

    Laterally constrained inversion (LCI) has been successfully applied to the inversion of dc resistivity, TEM and airborne EM data. However, it hasn't been yet applied to the interpretation of controlled-source audio-frequency magnetotelluric (CSAMT) data. In this paper, we apply the LCI method for CSAMT data inversion by preconditioning the Jacobian matrix. We apply a weighting matrix to Jacobian to balance the sensitivity of model parameters, so that the resolution with respect to different model parameters becomes more uniform. Numerical experiments confirm that this can improve the convergence of the inversion. We first invert a synthetic dataset with and without noise to investigate the effect of LCI applications to CSAMT data, for the noise free data, the results show that the LCI method can recover the true model better compared to the traditional single-station inversion; and for the noisy data, the true model is recovered even with a noise level of 8%, indicating that LCI inversions are to some extent noise insensitive. Then, we re-invert two CSAMT datasets collected respectively in a watershed and a coal mine area in Northern China and compare our results with those from previous inversions. The comparison with the previous inversion in a coal mine shows that LCI method delivers smoother layer interfaces that well correlate to seismic data, while comparison with a global searching algorithm of simulated annealing (SA) in a watershed shows that though both methods deliver very similar good results, however, LCI algorithm presented in this paper runs much faster. The inversion results for the coal mine CSAMT survey show that a conductive water-bearing zone that was not revealed by the previous inversions has been identified by the LCI. This further demonstrates that the method presented in this paper works for CSAMT data inversion.

  2. Kinematics and control of redundant robotic arm based on dielectric elastomer actuators

    NASA Astrophysics Data System (ADS)

    Branz, Francesco; Antonello, Andrea; Carron, Andrea; Carli, Ruggero; Francesconi, Alessandro

    2015-04-01

    Soft robotics is a promising field and its application to space mechanisms could represent a breakthrough in space technologies by enabling new operative scenarios (e.g. soft manipulators, capture systems). Dielectric Elastomers Actuators have been under deep study for a number of years and have shown several advantages that could be of key importance for space applications. Among such advantages the most notable are high conversion efficiency, distributed actuation, self-sensing capability, multi-degree-of-freedom design, light weight and low cost. The big potentialities of double cone actuators have been proven in terms of good performances (i.e. stroke and force/torque), ease of manufacturing and durability. In this work the kinematic, dynamic and control design of a two-joint redundant robotic arm is presented. Two double cone actuators are assembled in series to form a two-link design. Each joint has two degrees of freedom (one rotational and one translational) for a total of four. The arm is designed to move in a 2-D environment (i.e. the horizontal plane) with 4 DoF, consequently having two degrees of redundancy. The redundancy is exploited in order to minimize the joint loads. The kinematic design with redundant Jacobian inversion is presented. The selected control algorithm is described along with the results of a number of dynamic simulations that have been executed for performance verification. Finally, an experimental setup is presented based on a flexible structure that counteracts gravity during testing in order to better emulate future zero-gravity applications.

  3. Bose and Fermi statistics and the regularization of the nonrelativistic Jacobian for the scale anomaly

    NASA Astrophysics Data System (ADS)

    Lin, Chris L.; Ordóñez, Carlos R.

    2016-10-01

    We regulate in Euclidean space the Jacobian under scale transformations for two-dimensional nonrelativistic fermions and bosons interacting via contact interactions and compare the resulting scaling anomalies. For fermions, Grassmannian integration inverts the Jacobian; however, this effect is canceled by the regularization procedure and a result similar to that of bosons is attained. We show the independence of the result with respect to the regulating function, and show the robustness of our methods by comparing the procedure with an effective potential method using both cutoff and ζ -function regularization.

  4. Using ADIFOR and ADIC to provide Jacobians for the SNES component of PETSc

    SciTech Connect

    Wu, Po-Ting; Bischof, C.H.; Hovland, P.D.

    1997-11-01

    The solution of large-scale nonlinear problems is important to many areas of computational science. The SNES component of PETSc provides a robust and flexible suite of numerical routines for the solving such problems. These routines generally utilize the Jacobian matrix. We present a strategy for using ADIFOR or ADIC to assist in the development of a subroutine for computing this matrix. We illustrate this strategy using one of the PETSc example programs and four different approaches to computing the Jacobian via automatic differentiation.

  5. Kinematic functions for the 7 DOF robotics research arm

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

    The Robotics Research Model K-1207 manipulator is a redundant 7R serial link arm with offsets at all joints. To uniquely determine joint angles for a given end-effector configuration, the redundancy is parameterized by a scalar variable which corresponds to the angle between the manipulator elbow plane and the vertical plane. The forward kinematic mappings from joint-space to end-effector configuration and elbow angle, and the augmented Jacobian matrix which gives end-effector and elbow angle rates as a function of joint rates, are also derived.

  6. Magnetotelluric inversion via reverse time migration algorithm of seismic data

    SciTech Connect

    Ha, Taeyoung . E-mail: tyha@math.snu.ac.kr; Shin, Changsoo . E-mail: css@model.snu.ac.kr

    2007-07-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Kamei, R.; Pratt, R. G.

    2013-12-01

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

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

    NASA Technical Reports Server (NTRS)

    Vinokur, Marcel

    1988-01-01

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

  9. Fault tolerant kinematic control of hyper-redundant manipulators

    NASA Technical Reports Server (NTRS)

    Bedrossian, Nazareth S.

    1994-01-01

    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.

  10. Extracting the left and right critical eigenvectors from the LDU-decomposed non-symmetric Jacobian matrix in stability problems

    NASA Astrophysics Data System (ADS)

    Fujii, Fumio; Yamakawa, Yuki; Noguchi, Hirohisa

    2010-07-01

    In the previous publications of the authors, an eigenanalysis-free computational procedure has been proposed to extract the bifurcation buckling mode(s) from the LDL T -decomposed symmetric stiffness matrix in the vicinity of a stability point. Any eigensolver, for instance, inverse iteration or subspace method, is not necessary. The procedure has been verified in numerical examples and well works in multiple and clustered bifurcation problems too. This present paper will extend the eigenanalysis-free procedure to the LDU-decomposed non-symmetric Jacobian matrix, from which both left and right critical eigenvectors relevant to the stability point may be extracted in a similar way. The idea is mathematical and totally independent of the physical problem to be solved, so that it is applicable to any non-symmetric square matrix in stability problems including plasticity with non-associated flow rules, contact and fluid-structure interaction. The linear-algebraic background of non-symmetric eigenvalue problems is firstly described. The present paper will then mention the role play of the left and right critical eigenvectors in stability analysis and the eigenanalysis-free LDU-procedure is proposed. Numerical examples of elastoplastic bifurcation are illustrated for verification and discussion. In APPENDICES, a bench model visualizes the mechanical meaning of the left and right critical singular vectors of a rectangular matrix.

  11. On the kinematic analysis of robotic mechanisms

    SciTech Connect

    Nielsen, J.; Roth, B.

    1999-12-01

    The kinematic analyses, of manipulators and other robotic devices composed of mechanical links, usually depend on the solution of sets of nonlinear equations. There are a variety of both numerical and algebraic techniques available to solve such systems of equations and to give bounds on the number of solutions. These solution methods have also led to an understanding of how special choices of the various structural parameters of a mechanism influence the number of solutions inherent to the kinematic geometry of a given structure. In this paper, results from studying the kinematic geometry of such systems are reviewed, and the three most useful solution techniques are summarized. The solution techniques are polynomial continuation, Groebner bases, and elimination. The authors then discuss the results that have been obtained with these techniques in the solution of two basic problems, namely, the inverse kinematics for serial-chain manipulators, and the direct kinematics of in-parallel platform devices.

  12. A Constrained Multibody System Dynamics Avoiding Kinematic Singularities

    NASA Astrophysics Data System (ADS)

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

    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.

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

    SciTech Connect

    Bischof, C.; Hovland, P.

    1992-01-01

    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.

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

    SciTech Connect

    Bischof, C.; Hovland, P.

    1992-01-01

    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.

  15. Dynamics on strata of trigonal Jacobians and some integrable problems of rigid body motion

    NASA Astrophysics Data System (ADS)

    Braden, H. W.; Enolski, V. Z.; Fedorov, Yu N.

    2013-07-01

    We present an algebraic geometrical and analytical description of the Goryachev case of rigid body motion. It belongs to a family of systems sharing the same properties: although completely integrable, they are not algebraically integrable, their solution is not meromorphic in the complex time and involves dynamics on the strata of the Jacobian varieties of trigonal curves. Although the strata of hyperelliptic Jacobians have already appeared in the literature in the context of some dynamical systems, the Goryachev case is the first example of an integrable system whose solution involves a more general curve. Several new features (and formulae) are encountered in the solution given in terms of sigma-functions of such a curve.

  16. New preconditioning strategy for Jacobian-free solvers for variably saturated flows with Richards' equation

    NASA Astrophysics Data System (ADS)

    Lipnikov, Konstantin; Moulton, David; Svyatskiy, Daniil

    2016-08-01

    We develop a new approach for solving the nonlinear Richards' equation arising in variably saturated flow modeling. The growing complexity of geometric models for simulation of subsurface flows leads to the necessity of using unstructured meshes and advanced discretization methods. Typically, a numerical solution is obtained by first discretizing PDEs and then solving the resulting system of nonlinear discrete equations with a Newton-Raphson-type method. Efficiency and robustness of the existing solvers rely on many factors, including an empiric quality control of intermediate iterates, complexity of the employed discretization method and a customized preconditioner. We propose and analyze a new preconditioning strategy that is based on a stable discretization of the continuum Jacobian. We will show with numerical experiments for challenging problems in subsurface hydrology that this new preconditioner improves convergence of the existing Jacobian-free solvers 3-20 times. We also show that the Picard method with this preconditioner becomes a more efficient nonlinear solver than a few widely used Jacobian-free solvers.

  17. New preconditioning strategy for Jacobian-free solvers for variably saturated flows with Richards’ equation

    DOE PAGES

    Lipnikov, Konstantin; Moulton, David; Svyatskiy, Daniil

    2016-04-29

    We develop a new approach for solving the nonlinear Richards’ equation arising in variably saturated flow modeling. The growing complexity of geometric models for simulation of subsurface flows leads to the necessity of using unstructured meshes and advanced discretization methods. Typically, a numerical solution is obtained by first discretizing PDEs and then solving the resulting system of nonlinear discrete equations with a Newton-Raphson-type method. Efficiency and robustness of the existing solvers rely on many factors, including an empiric quality control of intermediate iterates, complexity of the employed discretization method and a customized preconditioner. We propose and analyze a new preconditioningmore » strategy that is based on a stable discretization of the continuum Jacobian. We will show with numerical experiments for challenging problems in subsurface hydrology that this new preconditioner improves convergence of the existing Jacobian-free solvers 3-20 times. Furthermore, we show that the Picard method with this preconditioner becomes a more efficient nonlinear solver than a few widely used Jacobian-free solvers.« less

  18. Modal kinematics for multisection continuum arms.

    PubMed

    Godage, Isuru S; Medrano-Cerda, Gustavo A; Branson, David T; Guglielmino, Emanuele; Caldwell, Darwin G

    2015-05-13

    This paper presents a novel spatial kinematic model for multisection continuum arms based on mode shape functions (MSF). Modal methods have been used in many disciplines from finite element methods to structural analysis to approximate complex and nonlinear parametric variations with simple mathematical functions. Given certain constraints and required accuracy, this helps to simplify complex phenomena with numerically efficient implementations leading to fast computations. A successful application of the modal approximation techniques to develop a new modal kinematic model for general variable length multisection continuum arms is discussed. The proposed method solves the limitations associated with previous models and introduces a new approach for readily deriving exact, singularity-free and unique MSF's that simplifies the approach and avoids mode switching. The model is able to simulate spatial bending as well as straight arm motions (i.e., pure elongation/contraction), and introduces inverse position and orientation kinematics for multisection continuum arms. A kinematic decoupling feature, splitting position and orientation inverse kinematics is introduced. This type of decoupling has not been presented for these types of robotic arms before. The model also carefully accounts for physical constraints in the joint space to provide enhanced insight into practical mechanics and impose actuator mechanical limitations onto the kinematics thus generating fully realizable results. The proposed method is easily applicable to a broad spectrum of continuum arm designs.

  19. Modal kinematics for multisection continuum arms.

    PubMed

    Godage, Isuru S; Medrano-Cerda, Gustavo A; Branson, David T; Guglielmino, Emanuele; Caldwell, Darwin G

    2015-06-01

    This paper presents a novel spatial kinematic model for multisection continuum arms based on mode shape functions (MSF). Modal methods have been used in many disciplines from finite element methods to structural analysis to approximate complex and nonlinear parametric variations with simple mathematical functions. Given certain constraints and required accuracy, this helps to simplify complex phenomena with numerically efficient implementations leading to fast computations. A successful application of the modal approximation techniques to develop a new modal kinematic model for general variable length multisection continuum arms is discussed. The proposed method solves the limitations associated with previous models and introduces a new approach for readily deriving exact, singularity-free and unique MSF's that simplifies the approach and avoids mode switching. The model is able to simulate spatial bending as well as straight arm motions (i.e., pure elongation/contraction), and introduces inverse position and orientation kinematics for multisection continuum arms. A kinematic decoupling feature, splitting position and orientation inverse kinematics is introduced. This type of decoupling has not been presented for these types of robotic arms before. The model also carefully accounts for physical constraints in the joint space to provide enhanced insight into practical mechanics and impose actuator mechanical limitations onto the kinematics thus generating fully realizable results. The proposed method is easily applicable to a broad spectrum of continuum arm designs. PMID:25969947

  20. Principal Component Geostatistical Approach for large-dimensional inverse problems

    PubMed Central

    Kitanidis, P K; Lee, J

    2014-01-01

    The quasi-linear geostatistical approach is for weakly nonlinear underdetermined inverse problems, such as Hydraulic Tomography and Electrical Resistivity Tomography. It provides best estimates as well as measures for uncertainty quantification. However, for its textbook implementation, the approach involves iterations, to reach an optimum, and requires the determination of the Jacobian matrix, i.e., the derivative of the observation function with respect to the unknown. Although there are elegant methods for the determination of the Jacobian, the cost is high when the number of unknowns, m, and the number of observations, n, is high. It is also wasteful to compute the Jacobian for points away from the optimum. Irrespective of the issue of computing derivatives, the computational cost of implementing the method is generally of the order of m2n, though there are methods to reduce the computational cost. In this work, we present an implementation that utilizes a matrix free in terms of the Jacobian matrix Gauss-Newton method and improves the scalability of the geostatistical inverse problem. For each iteration, it is required to perform K runs of the forward problem, where K is not just much smaller than m but can be smaller that n. The computational and storage cost of implementation of the inverse procedure scales roughly linearly with m instead of m2 as in the textbook approach. For problems of very large m, this implementation constitutes a dramatic reduction in computational cost compared to the textbook approach. Results illustrate the validity of the approach and provide insight in the conditions under which this method perform best. PMID:25558113

  1. Principal Component Geostatistical Approach for large-dimensional inverse problems

    NASA Astrophysics Data System (ADS)

    Kitanidis, P. K.; Lee, J.

    2014-07-01

    The quasi-linear geostatistical approach is for weakly nonlinear underdetermined inverse problems, such as Hydraulic Tomography and Electrical Resistivity Tomography. It provides best estimates as well as measures for uncertainty quantification. However, for its textbook implementation, the approach involves iterations, to reach an optimum, and requires the determination of the Jacobian matrix, i.e., the derivative of the observation function with respect to the unknown. Although there are elegant methods for the determination of the Jacobian, the cost is high when the number of unknowns, m, and the number of observations, n, is high. It is also wasteful to compute the Jacobian for points away from the optimum. Irrespective of the issue of computing derivatives, the computational cost of implementing the method is generally of the order of m2n, though there are methods to reduce the computational cost. In this work, we present an implementation that utilizes a matrix free in terms of the Jacobian matrix Gauss-Newton method and improves the scalability of the geostatistical inverse problem. For each iteration, it is required to perform K runs of the forward problem, where K is not just much smaller than m but can be smaller that n. The computational and storage cost of implementation of the inverse procedure scales roughly linearly with m instead of m2 as in the textbook approach. For problems of very large m, this implementation constitutes a dramatic reduction in computational cost compared to the textbook approach. Results illustrate the validity of the approach and provide insight in the conditions under which this method perform best.

  2. Implementing a Matrix-free Analytical Jacobian to Handle Nonlinearities in Models of 3D Lithospheric Deformation

    NASA Astrophysics Data System (ADS)

    Kaus, B.; Popov, A.

    2015-12-01

    The analytical expression for the Jacobian is a key component to achieve fast and robust convergence of the nonlinear Newton-Raphson iterative solver. Accomplishing this task in practice often requires a significant algebraic effort. Therefore it is quite common to use a cheap alternative instead, for example by approximating the Jacobian with a finite difference estimation. Despite its simplicity it is a relatively fragile and unreliable technique that is sensitive to the scaling of the residual and unknowns, as well as to the perturbation parameter selection. Unfortunately no universal rule can be applied to provide both a robust scaling and a perturbation. The approach we use here is to derive the analytical Jacobian for the coupled set of momentum, mass, and energy conservation equations together with the elasto-visco-plastic rheology and a marker in cell/staggered finite difference method. The software project LaMEM (Lithosphere and Mantle Evolution Model) is primarily developed for the thermo-mechanically coupled modeling of the 3D lithospheric deformation. The code is based on a staggered grid finite difference discretization in space, and uses customized scalable solvers form PETSc library to efficiently run on the massively parallel machines (such as IBM Blue Gene/Q). Currently LaMEM relies on the Jacobian-Free Newton-Krylov (JFNK) nonlinear solver, which approximates the Jacobian-vector product using a simple finite difference formula. This approach never requires an assembled Jacobian matrix and uses only the residual computation routine. We use an approximate Jacobian (Picard) matrix to precondition the Krylov solver with the Galerkin geometric multigrid. Because of the inherent problems of the finite difference Jacobian estimation, this approach doesn't always result in stable convergence. In this work we present and discuss a matrix-free technique in which the Jacobian-vector product is replaced by analytically-derived expressions and compare results

  3. Kinematics Analysis of an Aided Robot for Needle Insertion

    NASA Astrophysics Data System (ADS)

    Li, Qiang; Gao, Dedong; Wang, Shan; Bai, Huiquan; Zheng, Haojun

    The kinematic relationship between the needle base and the robot's joints is analyzed. The analysis process is based on the aided needle-insertion robot built by our group. The thinking of needle-inserting procedure is confirming the needle base's posture before the needle inserted into tissue. The method of Denavit-Hartenberg (D-H) parameters is used to establish a link robot body-frames with the structural characteristics of the robot. After analysing kinematics, the kinematics equation is presented. The kinematics inverse solutions are obtained with the analytical method and geometry analysis method.

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

    PubMed

    Schiller, Helmut

    2007-05-01

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

  5. Finite field-dependent BRST-anti-BRST transformations: Jacobians and application to the Standard Model

    NASA Astrophysics Data System (ADS)

    Yu. Moshin, Pavel; Reshetnyak, Alexander A.

    2016-07-01

    We continue our research1-4 and extend the class of finite BRST-anti-BRST transformations with odd-valued parameters λa, a = 1, 2, introduced in these works. In doing so, we evaluate the Jacobians induced by finite BRST-anti-BRST transformations linear in functionally-dependent parameters, as well as those induced by finite BRST-anti-BRST transformations with arbitrary functional parameters. The calculations cover the cases of gauge theories with a closed algebra, dynamical systems with first-class constraints, and general gauge theories. The resulting Jacobians in the case of linearized transformations are different from those in the case of polynomial dependence on the parameters. Finite BRST-anti-BRST transformations with arbitrary parameters induce an extra contribution to the quantum action, which cannot be absorbed into a change of the gauge. These transformations include an extended case of functionally-dependent parameters that implies a modified compensation equation, which admits nontrivial solutions leading to a Jacobian equal to unity. Finite BRST-anti-BRST transformations with functionally-dependent parameters are applied to the Standard Model, and an explicit form of functionally-dependent parameters λa is obtained, providing the equivalence of path integrals in any 3-parameter Rξ-like gauges. The Gribov-Zwanziger theory is extended to the case of the Standard Model, and a form of the Gribov horizon functional is suggested in the Landau gauge, as well as in Rξ-like gauges, in a gauge-independent way using field-dependent BRST-anti-BRST transformations, and in Rξ-like gauges using transverse-like non-Abelian gauge fields.

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

    NASA Astrophysics Data System (ADS)

    Büsing, H.; Clauser, C.

    2012-04-01

    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.

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

    SciTech Connect

    Dana Knoll; HyeongKae Park; Chris Newman

    2011-02-01

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

  8. Compactified strings as quantum statistical partition function on the Jacobian torus.

    PubMed

    Matone, Marco; Pasti, Paolo; Shadchin, Sergey; Volpato, Roberto

    2006-12-31

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  10. Regularity of mappings inverse to Sobolev mappings

    SciTech Connect

    Vodop'yanov, Sergei K

    2012-10-31

    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.

  11. 3D-marine tCSEM inversion using model reduction in the Rational Krylov subspace

    NASA Astrophysics Data System (ADS)

    Sommer, M.; Jegen, M. D.

    2014-12-01

    Computationally, the most expensive part of a 3D time domain CSEM inversion is the computation of the Jacobian matrix in every Gauss-Newton step. An other problem is its size for large data sets. We use a model reduction method (Zaslavsky et al, 2013), that compresses the Jacobian by projecting it with a Rational Krylov Subspace (RKS). It also reduces the runtime drastically, compared to the most common adjoint approach and was implemented on GPU.It depends on an analytic derivation of the implicit Anzatz function, which solves Maxwell's diffusion equation in the Eigenspace giving a Jacobian dependent on the Eigenpairs and its derivatives of the forward problem. The Eigenpairs are approximated by Ritz-pairs in the Rational Krylov subspace. Determination of the derivived Ritz-pairs is the most time consuming and was fully GPU-optimized. Furthermore, the amount of inversion cells is reduced by using Octree meshes. The gridding allows for the incorporation of complicated survey geometries, as they are encountered in marine CSEM datasets.As a first result, the Jacobian computation is, even on a Desktop, faster than the most common adjoint approach on a super computer for realistic data sets. We will present careful benchmarking and accuracy tests of the new method and show how it can be applied to a real marine scenario.

  12. Integration of large chemical kinetic mechanisms via exponential methods with Krylov approximations to Jacobian matrix functions

    NASA Astrophysics Data System (ADS)

    Bisetti, Fabrizio

    2012-06-01

    Recent trends in hydrocarbon fuel research indicate that the number of species and reactions in chemical kinetic mechanisms is rapidly increasing in an effort to provide predictive capabilities for fuels of practical interest. In order to cope with the computational cost associated with the time integration of stiff, large chemical systems, a novel approach is proposed. The approach combines an exponential integrator and Krylov subspace approximations to the exponential function of the Jacobian matrix. The components of the approach are described in detail and applied to the ignition of stoichiometric methane-air and iso-octane-air mixtures, here described by two widely adopted chemical kinetic mechanisms. The approach is found to be robust even at relatively large time steps and the global error displays a nominal third-order convergence. The performance of the approach is improved by utilising an adaptive algorithm for the selection of the Krylov subspace size, which guarantees an approximation to the matrix exponential within user-defined error tolerance. The Krylov projection of the Jacobian matrix onto a low-dimensional space is interpreted as a local model reduction with a well-defined error control strategy. Finally, the performance of the approach is discussed with regard to the optimal selection of the parameters governing the accuracy of its individual components.

  13. A new Jacobian matrix for optimal learning of single-layer neural networks.

    PubMed

    Peng, Jian Xun; Li, Kang; Irwin, George W

    2008-01-01

    This paper investigates the learning of a wide class of single-hidden-layer feedforward neural networks (SLFNs) with two sets of adjustable parameters, i.e., the nonlinear parameters in the hidden nodes and the linear output weights. The main objective is to both speed up the convergence of second-order learning algorithms such as Levenberg-Marquardt (LM), as well as to improve the network performance. This is achieved here by reducing the dimension of the solution space and by introducing a new Jacobian matrix. Unlike conventional supervised learning methods which optimize these two sets of parameters simultaneously, the linear output weights are first converted into dependent parameters, thereby removing the need for their explicit computation. Consequently, the neural network (NN) learning is performed over a solution space of reduced dimension. A new Jacobian matrix is then proposed for use with the popular second-order learning methods in order to achieve a more accurate approximation of the cost function. The efficacy of the proposed method is shown through an analysis of the computational complexity and by presenting simulation results from four different examples. PMID:18269943

  14. Code Coupling via Jacobian-Free Newton-Krylov Algorithms with Application to Magnetized Fluid Plasma and Kinetic Neutral Models

    SciTech Connect

    Joseph, Ilon

    2014-05-27

    Jacobian-free Newton-Krylov (JFNK) algorithms are a potentially powerful class of methods for solving the problem of coupling codes that address dfferent physics models. As communication capability between individual submodules varies, different choices of coupling algorithms are required. The more communication that is available, the more possible it becomes to exploit the simple sparsity pattern of the Jacobian, albeit of a large system. The less communication that is available, the more dense the Jacobian matrices become and new types of preconditioners must be sought to efficiently take large time steps. In general, methods that use constrained or reduced subsystems can offer a compromise in complexity. The specific problem of coupling a fluid plasma code to a kinetic neutrals code is discussed as an example.

  15. Application of the least-squares inversion method: Fourier series versus waveform inversion

    NASA Astrophysics Data System (ADS)

    Min, Dong-Joo; Shin, Jungkyun; Shin, Changsoo

    2015-11-01

    We describe an implicit link between waveform inversion and Fourier series based on inversion methods such as gradient, Gauss-Newton, and full Newton methods. Fourier series have been widely used as a basic concept in studies on seismic data interpretation, and their coefficients are obtained in the classical Fourier analysis. We show that Fourier coefficients can also be obtained by inversion algorithms, and compare the method to seismic waveform inversion algorithms. In that case, Fourier coefficients correspond to model parameters (velocities, density or elastic constants), whereas cosine and sine functions correspond to components of the Jacobian matrix, that is, partial derivative wavefields in seismic inversion. In the classical Fourier analysis, optimal coefficients are determined by the sensitivity of a given function to sine and cosine functions. In the inversion method for Fourier series, Fourier coefficients are obtained by measuring the sensitivity of residuals between given functions and test functions (defined as the sum of weighted cosine and sine functions) to cosine and sine functions. The orthogonal property of cosine and sine functions makes the full or approximate Hessian matrix become a diagonal matrix in the inversion for Fourier series. In seismic waveform inversion, the Hessian matrix may or may not be a diagonal matrix, because partial derivative wavefields correlate with each other to some extent, making them semi-orthogonal. At the high-frequency limits, however, the Hessian matrix can be approximated by either a diagonal matrix or a diagonally-dominant matrix. Since we usually deal with relatively low frequencies in seismic waveform inversion, it is not diagonally dominant and thus it is prohibitively expensive to compute the full or approximate Hessian matrix. By interpreting Fourier series with the inversion algorithms, we note that the Fourier series can be computed at an iteration step using any inversion algorithms such as the

  16. Real time markerless motion tracking using linked kinematic chains

    DOEpatents

    Luck, Jason P.; Small, Daniel E.

    2007-08-14

    A markerless method is described for tracking the motion of subjects in a three dimensional environment using a model based on linked kinematic chains. The invention is suitable for tracking robotic, animal or human subjects in real-time using a single computer with inexpensive video equipment, and does not require the use of markers or specialized clothing. A simple model of rigid linked segments is constructed of the subject and tracked using three dimensional volumetric data collected by a multiple camera video imaging system. A physics based method is then used to compute forces to align the model with subsequent volumetric data sets in real-time. The method is able to handle occlusion of segments and accommodates joint limits, velocity constraints, and collision constraints and provides for error recovery. The method further provides for elimination of singularities in Jacobian based calculations, which has been problematic in alternative methods.

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

    NASA Astrophysics Data System (ADS)

    Andersen, David R.; Bershady, Matthew A.

    2013-05-01

    Using the integral field unit DensePak on the WIYN 3.5 m telescope we have obtained Hα 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.

  18. Testing earthquake source inversion methodologies

    USGS Publications Warehouse

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

    2011-01-01

    Source Inversion Validation Workshop; Palm Springs, California, 11-12 September 2010; Nowadays earthquake source inversions are routinely performed after large earthquakes and represent a key connection between recorded seismic and geodetic data and the complex rupture process at depth. The resulting earthquake source models quantify the spatiotemporal evolution of ruptures. They are also used to provide a rapid assessment of the severity of an earthquake and to estimate losses. However, because of uncertainties in the data, assumed fault geometry and velocity structure, and chosen rupture parameterization, it is not clear which features of these source models are robust. Improved understanding of the uncertainty and reliability of earthquake source inversions will allow the scientific community to use the robust features of kinematic inversions to more thoroughly investigate the complexity of the rupture process and to better constrain other earthquakerelated computations, such as ground motion simulations and static stress change calculations.

  19. Inversions for axisymmetric galactic disks

    NASA Astrophysics Data System (ADS)

    Hiotelis, N.; Patsis, P. A.

    1993-08-01

    We use two models for the distribution function to solve an inverse problem for axisymmetric disks. These systems may be considered - under certain assumptions - as galactic disks. In some cases the solutions of the resulting integral equations are simple, which allows the determination of the kinematic properties of self-consistent models for these systems. These properties for then = 1 Toomre disk are presented in this study.

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

    SciTech Connect

    Tashmasebi, F.; Tsai, Lung-Wen

    1992-08-01

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

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

    SciTech Connect

    Tashmasebi, F. . Goddard Space Flight Center); Tsai, Lung-Wen . Dept. of Mechanical Engineering)

    1992-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Garand, L.; Turner, D. S.; Larocque, M.; Bates, J.; Boukabara, S.; Brunel, P.; Chevallier, F.; Deblonde, G.; Engelen, R.; Atlas, Robert (Technical Monitor)

    2000-01-01

    The goals of this study are the evaluation of current fast radiative transfer models (RTMs) and line-by-line (LBL) models. The intercomparison focuses on the modeling of 11 representative sounding channels routinely used at numerical weather prediction centers: seven HIRS (High-resolution Infrared Sounder) and four AMSU (Advanced Microwave Sounding Unit) channels. Interest in this topic was evidenced by the participation of 24 scientists from 16 institutions. An ensemble of 42 diverse atmospheres was used and results compiled for 19 infrared models and 10 microwave models, including several LBL RTMs. For the first time, not only radiances, but also Jacobians (of temperature, water vapor, and ozone) were compared to various LBL models for many channels. In the infrared, LBL models typically agree to within 0.05-0.15 K (standard deviation) in terms of top-of-the-atmosphere brightness temperature (BT). Individual differences up to 0.5 K still exist, systematic in some channels, and linked to the type of atmosphere in others. The best fast models emulate LBL BTs to within 0.25 K, but no model achieves this desirable level of success for all channels. The ozone modeling is particularly challenging. In the microwave, fast models generally do quite well against the LBL model to which they were tuned. However significant differences were noted among LBL models. Extending the intercomparison to the Jacobians proved very useful in detecting subtle and more obvious modeling errors. In addition, total and single gas optical depths were calculated, which provided additional insight on the nature of differences. Recommendations for future intercomparisons are suggested.

  3. Augmented kinematic feedback system

    NASA Astrophysics Data System (ADS)

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

    1994-07-01

    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.

  4. New 3D parallel SGILD modeling and inversion

    SciTech Connect

    Xie, G.; Li, J.; Majer, E.

    1998-09-01

    In this paper, a new parallel modeling and inversion algorithm using a Stochastic Global Integral and Local Differential equation (SGILD) is presented. The authors derived new acoustic integral equations and differential equation for statistical moments of the parameters and field. The new statistical moments integral equation on the boundary and local differential equations in domain will be used together to obtain mean wave field and its moments in the modeling. The new moments global Jacobian volume integral equation and the local Jacobian differential equations in domain will be used together to update the mean parameters and their moments in the inversion. A new parallel multiple hierarchy substructure direct algorithm or direct-iteration hybrid algorithm will be used to solve the sparse matrices and one smaller full matrix from domain to the boundary, in parallel. The SGILD modeling and imaging algorithm has many advantages over the conventional imaging approaches. The SGILD algorithm can be used for the stochastic acoustic, electromagnetic, and flow modeling and inversion, and are important for the prediction of oil, gas, coal, and geothermal energy reservoirs in geophysical exploration.

  5. Kinematic synthesis of bevel-gear-type robotic wrist mechanisms

    NASA Astrophysics Data System (ADS)

    Lin, Chen-Chou

    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. kinematic performance.

  6. Chow groups of intersections of quadrics via homological projective duality and (Jacobians of) non-commutative motives

    NASA Astrophysics Data System (ADS)

    Bernardara, M.; Tabuada, G.

    2016-06-01

    Conjectures of Beilinson-Bloch type predict that the low-degree rational Chow groups of intersections of quadrics are one-dimensional. This conjecture was proved by Otwinowska in [20]. By making use of homological projective duality and the recent theory of (Jacobians of) non-commutative motives, we give an alternative proof of this conjecture in the case of a complete intersection of either two quadrics or three odd-dimensional quadrics. Moreover, we prove that in these cases the unique non-trivial algebraic Jacobian is the middle one. As an application, we make use of Vial's work [26], [27] to describe the rational Chow motives of these complete intersections and show that smooth fibrations into such complete intersections over bases S of small dimension satisfy Murre's conjecture (when \\dim (S)≤ 1), Grothendieck's standard conjecture of Lefschetz type (when \\dim (S)≤ 2), and Hodge's conjecture (when \\dim(S)≤ 3).

  7. Tetrahedral Element Shape Optimization via the Jacobian Determinant and Condition Number

    SciTech Connect

    FREITAG,LORI A.; KNUPP,PATRICK

    1999-09-27

    We present a new shape measure for tetrahedral elements that is optimal in the sense that it gives the distance of a tetrahedron from the set of inverted elements. This measure is constructed from the condition number of the linear transformation between a unit equilateral tetrahedron and any tetrahedron with positive volume. We use this shape measure to formulate two optimization objective functions that are differentiated by their goal: the first seeks to improve the average quality of the tetrahedral mesh; the second aims to improve the worst-quality element in the mesh. Because the element condition number is not defined for tetrahedral with negative volume, these objective functions can be used only when the initial mesh is valid. Therefore, we formulate a third objective function using the determinant of the element Jacobian that is suitable for mesh untangling. We review the optimization techniques used with each objective function and present experimental results that demonstrate the effectiveness of the mesh improvement and untangling methods. We show that a combined optimization approach that uses both condition number objective functions obtains the best-quality meshes.

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

    NASA Astrophysics Data System (ADS)

    Hansen, Glen

    2011-07-01

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

  9. Phenomenological study of irregular cellular automata based on Lyapunov exponents and Jacobians

    NASA Astrophysics Data System (ADS)

    Baetens, Jan M.; De Baets, Bernard

    2010-09-01

    Originally, cellular automata (CA) have been defined upon regular tessellations of the n-dimensional Euclidean space, while CA on irregular tessellations have received only little attention from the scientific community, notwithstanding serious shortcomings are associated with the former manner of subdividing Rn. In this paper we present a profound phenomenological study of two-state, two-dimensional irregular CA from a dynamical systems viewpoint. We opted to exploit properly defined quantitative measures instead of resorting to qualitative methods for discriminating between behavioral classes. As such, we employ Lyapunov exponents, measuring the divergence rate of close trajectories in phase space, and Jacobians, formulated using Boolean derivatives and expressing the sensitivity of a cellular automaton to its inputs. Both are stated for two-state CA on irregular tessellations, enabling us to characterize these discrete dynamical systems, and advancing us to propose a classification scheme for this CA family. In addition, a relationship between these quantitative measures is established in extension of the insights already developed for the classical CA paradigm. Finally, we discuss the repercussions on the CA dynamics that arise when the geometric variability of the spatial entities is taken into account during the CA simulation.

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

    PubMed

    Furuya, Takashi; Saito, Shuji; Araki, Mitsunori

    2007-12-28

    Inversion-rotation spectral lines of the monodeuterated hydronium ion, H(2)DO(+), have been observed by a source-modulation spectrometer in the millimeter- to submillimeter-wave region. The ion was generated by a hollow-cathode discharge in a gas mixture of H(2)O and D(2)O. Nine inversion-rotation lines were measured precisely for the lowest pair of inversion doublets in the frequency region from 210 to 720 GHz. The measured lines were analyzed to derive rotational constants in the inversion-doublet states and inversion splitting. The inversion splitting in the ground state was determined to be 1,215,866(410) MHz, that is, 40.5569(137) cm(-1), where the numbers in parentheses give probable uncertainties estimated from the Jacobian matrix of the assumed centrifugal distortion constants of the inversion-doublet states. The determined inversion splitting is off by -0.58 cm(-1) from the predicted value of 41.14 cm(-1) by Rayamaki et al. using high-order coupled cluster ab initio calculations [J. Chem. Phys. 118, 10929 (2003)], and by 0.039 cm(-1) from the observed value of 40.518(10) cm(-1) by Dong and Nesbitt using high-resolution jet-cooled infrared spectroscopy [J. Chem. Phys. 125, 144311 (2006)] beyond the quoted uncertainty. The most astronomically important transition 0(00)(-)-1(0)(+) for the ortho species was measured at 673,257.024(31) MHz, which could be used as a radioastronomical probe investigating interstellar chemistry of deuterium fractionation in space.

  11. Pelvis and torso kinematics and their relationship to shoulder kinematics in high-school baseball pitchers.

    PubMed

    Oliver, Gretchen D; Keeley, David W

    2010-12-01

    It was the purpose of our study to examine the kinematics of the pelvis and torso and determine their relationship to the kinematics of the shoulder in high-school baseball pitchers. A single group, repeated-measures design was used to collect pelvis, torso, and shoulder kinematics throughout the pitching motion. Subjects threw a series of maximal effort fastballs to a catcher located the regulation distance (18.44m) from the pitching mound, and those data from the fastest pitch passing through the strike zone were analyzed. After test trials, kinematic data were analyzed using a series of descriptive statistics to identify outliers and determine the nature of the distribution before testing for the presence of relationships between the various parameters. Results indicated that for several parameters, the actions at and about the shoulder are strongly related to the actions of the pelvis and torso throughout the pitching motion. However, although pelvis and torso kinematics throughout the pitching motion were inversely related to both shoulder elevation and the plane of shoulder elevation, only the rate of axial torso rotation was significantly related to these shoulder parameters. More importantly, the rate of axial torso rotation is significantly related to these shoulder parameters in a way that may help explain the high rate of shoulder injury in high-school pitchers. Therefore, strength training should focus on developing a strong stable core including the gluteal musculature in an attempt to control the rate of torso rotation during the pitch. PMID:20703168

  12. Pelvis and torso kinematics and their relationship to shoulder kinematics in high-school baseball pitchers.

    PubMed

    Oliver, Gretchen D; Keeley, David W

    2010-12-01

    It was the purpose of our study to examine the kinematics of the pelvis and torso and determine their relationship to the kinematics of the shoulder in high-school baseball pitchers. A single group, repeated-measures design was used to collect pelvis, torso, and shoulder kinematics throughout the pitching motion. Subjects threw a series of maximal effort fastballs to a catcher located the regulation distance (18.44m) from the pitching mound, and those data from the fastest pitch passing through the strike zone were analyzed. After test trials, kinematic data were analyzed using a series of descriptive statistics to identify outliers and determine the nature of the distribution before testing for the presence of relationships between the various parameters. Results indicated that for several parameters, the actions at and about the shoulder are strongly related to the actions of the pelvis and torso throughout the pitching motion. However, although pelvis and torso kinematics throughout the pitching motion were inversely related to both shoulder elevation and the plane of shoulder elevation, only the rate of axial torso rotation was significantly related to these shoulder parameters. More importantly, the rate of axial torso rotation is significantly related to these shoulder parameters in a way that may help explain the high rate of shoulder injury in high-school pitchers. Therefore, strength training should focus on developing a strong stable core including the gluteal musculature in an attempt to control the rate of torso rotation during the pitch.

  13. An optimal resolved rate law for kinematically redundant manipulators

    NASA Technical Reports Server (NTRS)

    Bourgeois, B. J.

    1987-01-01

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

  14. Kinematic analysis of platform-type robotic manipulators

    NASA Astrophysics Data System (ADS)

    Shi, Xiaolun

    New methods are developed for the kinematic analysis of serial and platform-type parallel robotic manipulators, including forward and inverse kinematic solutions, singularity identifications and workspace evaluation. Differences between serial and platform-type parallel manipulators, which can provide substantially improved end-point rigidity compared with the conventional serial robotic arms, are addressed. The problem of determining the screw parameters of rigid body motion from initial and final position data is discussed, as a basis to search for a general and efficient procedure to solve the complex forward kinematics problem of platform-type manipulators. Several Screw-Theory based approaches for solving the inverse instantaneous problem of 6 DOF serial manipulators are studied and compared in terms of their computational efficiency, accuracy, sensitivity to data error and capability of dealing with singularities. A modified Vector Decomposition method is then proposed for solving the IIK problem and for singularity analysis of serial kinematic chains, the method is especially effective when applied to the wrist partitioned serial manipulators, which are essential components to any platform-type parallel manipulators. By using the data of three point positions, velocities, and accelerations of the end effector a general method is developed for solving the forward kinematics problem, including position, velocity and acceleration kinematics, of platform-type manipulators. The solution procedure can be applied to a wide variety of platform-type manipulators such as the 6 DOF Steward Platform manipulator and other models. It is found that while the solution for the forward position kinematics of a platform-type manipulator can be obtained by solving a non-linear system of equations, the closed-form solutions for forward rate and acceleration kinematics can be found by solving a system of linear equations. Based on the proposed kinematic formulations, an algorithm

  15. Three tooth kinematic coupling

    SciTech Connect

    Hale, L.C.

    2000-05-23

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

  16. Three tooth kinematic coupling

    SciTech Connect

    Hale, Layton C.

    2000-01-01

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

  17. Indirect inversions

    NASA Astrophysics Data System (ADS)

    Sergienko, Olga

    2013-04-01

    Since Doug MacAyeal's pioneering studies of the ice-stream basal traction optimizations by control methods, inversions for unknown parameters (e.g., basal traction, accumulation patterns, etc) have become a hallmark of the present-day ice-sheet modeling. The common feature of such inversion exercises is a direct relationship between optimized parameters and observations used in the optimization procedure. For instance, in the standard optimization for basal traction by the control method, ice-stream surface velocities constitute the control data. The optimized basal traction parameters explicitly appear in the momentum equations for the ice-stream velocities (compared to the control data). The inversion for basal traction is carried out by minimization of the cost (or objective, misfit) function that includes the momentum equations facilitated by the Lagrange multipliers. Here, we build upon this idea, and demonstrate how to optimize for parameters indirectly related to observed data using a suite of nested constraints (like Russian dolls) with additional sets of Lagrange multipliers in the cost function. This method opens the opportunity to use data from a variety of sources and types (e.g., velocities, radar layers, surface elevation changes, etc.) in the same optimization process.

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

    SciTech Connect

    Andersen, David R.; Bershady, Matthew A. E-mail: mab@astro.wisc.edu

    2013-05-01

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

  19. Kinematics of Tape Recording.

    ERIC Educational Resources Information Center

    Coleman, J. J.

    1982-01-01

    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)

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

    PubMed

    Furuya, Takashi; Saito, Shuji

    2008-01-21

    Inversion-rotation spectral lines of the dideuterated hydronium ion, HD2O+, have been observed by a source-modulation millimeter- to submillimeter-wave spectrometer. The ion was generated by a hollow-cathode discharge in a gas mixture of D2O and H2O in a free-space cell. Ten inversion-rotation lines were measured precisely for the lowest pair of inversion doublets in the frequency region from 380 to 730 GHz. The observed lines include the most astronomically important transitions, 0(00) (-)-1(10)+ for the para species at 380 538.031(32) MHz and 1(01) (-)-1(11)+ for the ortho species at 728 420.189(34) MHz, which could be used as a radio astronomical probe investigating interstellar chemistry of deuterium fractionation. An analysis of the measured lines has yielded the rotational constants in the ground doublet states and the inversion splitting. The inversion splitting in the ground state was determined to be 808 866(34) MHz, that is, 26.980 87(113) cm(-1), where the numbers in parentheses give uncertainties estimated from the Jacobian matrix of the assumed centrifugal distortion constants. The determined inversion splitting is off by -0.51 cm(-1) from the predicted value of 27.49 cm(-1) by Rajamaki et al. using high-order coupled cluster ab initio calculation [J. Chem. Phys. 118, 10929 (2003)], and by -0.0510 cm(-1) from the observed value of 27.0318(72) cm(-1) by Dong et al. using high-resolution jet-cooled infrared spectroscopy [J. Chem. Phys. 122, 224301 (2005)] beyond the quoted uncertainty.

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

    SciTech Connect

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

    2008-09-01

    We present high-order accurate spatiotemporal discretization of all-speed flow solvers using Jacobian-free Newton Krylov framework. One of the key developments in this work is the physics-based preconditioner for the all-speed flow, which makes use of traditional semi-implicit schemes. The physics-based preconditioner is developed in the primitive variable form, which allows a straightforward separation of physical phenomena. Numerical examples demonstrate that the developed preconditioner effectively reduces the number of the Krylov iterations, and the efficiency is independent of the Mach number and mesh sizes under a fixed CFL condition.

  2. Global inversion for anisotropy during full-waveform inversion

    NASA Astrophysics Data System (ADS)

    Debens, H. A.; Warner, M.; Umpleby, A.

    2015-12-01

    Full-waveform inversion (FWI) is a powerful tool for quantitative estimation of high-resolution high-fidelity models of subsurface seismic parameters, typically P-wave velocity. The solution to FWI's posed nonlinear inverse problem is obtained via an iterative series of linearized local updates to a start model, assuming this model lies within the basin of attraction to the global minimum. Thanks to many successful published applications to three-dimensional (3D) field datasets, its advance has been rapid and driven in large-part by the oil and gas industry. The consideration of seismic anisotropy during FWI is of vital importance, as it holds influence over both the kinematics and dynamics of seismic waveforms. If not appropriately taken into account then inadequacies in the anisotropy model are likely to manifest as significant error in the recovered velocity model. Conventionally, anisotropic FWI employs either an a priori anisotropy model, held fixed during FWI, or it uses a multi-parameter local inversion scheme to recover the anisotropy as part of the FWI; both of these methods can be problematic. Constructing an anisotropy model prior to FWI often involves intensive (and hence expensive) iterative procedures, such as travel-time tomography or moveout velocity analysis. On the other hand, introducing multiple parameters to FWI itself increases the complexity of what is already an underdetermined inverse problem. We propose that global rather than local FWI can be used to recover the long-wavelength acoustic anisotropy model, and that this can then be followed by more-conventional local FWI to recover the detailed model. We validate this approach using a full 3D field dataset, demonstrating that it avoids problems associated to crosstalk that can bedevil local inversion schemes, and reconciles well with in situ borehole measurements. Although our approach includes a global inversion for anisotropy, it is nonetheless affordable and practical for 3D field data.

  3. Bayesian Kinematic Finite Fault Source Models (Invited)

    NASA Astrophysics Data System (ADS)

    Minson, S. E.; Simons, M.; Beck, J. L.

    2010-12-01

    Finite fault earthquake source models are inherently under-determined: there is no unique solution to the inverse problem of determining the rupture history at depth as a function of time and space when our data are only limited observations at the Earth's surface. Traditional inverse techniques rely on model constraints and regularization to generate one model from the possibly broad space of all possible solutions. However, Bayesian methods allow us to determine the ensemble of all possible source models which are consistent with the data and our a priori assumptions about the physics of the earthquake source. Until now, Bayesian techniques have been of limited utility because they are computationally intractable for problems with as many free parameters as kinematic finite fault models. We have developed a methodology called Cascading Adaptive Tempered Metropolis In Parallel (CATMIP) which allows us to sample very high-dimensional problems in a parallel computing framework. The CATMIP algorithm combines elements of simulated annealing and genetic algorithms with the Metropolis algorithm to dynamically optimize the algorithm's efficiency as it runs. We will present synthetic performance tests of finite fault models made with this methodology as well as a kinematic source model for the 2007 Mw 7.7 Tocopilla, Chile earthquake. This earthquake was well recorded by multiple ascending and descending interferograms and a network of high-rate GPS stations whose records can be used as near-field seismograms.

  4. Implicit solution of Navier-Stokes equations on staggered curvilinear grids using a Newton-Krylov method with a novel analytical Jacobian.

    NASA Astrophysics Data System (ADS)

    Borazjani, Iman; Asgharzadeh, Hafez

    2015-11-01

    Flow simulations involving complex geometries and moving boundaries suffer from time-step size restriction and low convergence rates with explicit and semi-implicit schemes. Implicit schemes can be used to overcome these restrictions. However, implementing implicit solver for nonlinear equations including Navier-Stokes is not straightforward. Newton-Krylov subspace methods (NKMs) are one of the most advanced iterative methods to solve non-linear equations such as implicit descritization of the Navier-Stokes equation. The efficiency of NKMs massively depends on the Jacobian formation method, e.g., automatic differentiation is very expensive, and matrix-free methods slow down as the mesh is refined. Analytical Jacobian is inexpensive method, but derivation of analytical Jacobian for Navier-Stokes equation on staggered grid is challenging. The NKM with a novel analytical Jacobian was developed and validated against Taylor-Green vortex and pulsatile flow in a 90 degree bend. The developed method successfully handled the complex geometries such as an intracranial aneurysm with multiple overset grids, and immersed boundaries. It is shown that the NKM with an analytical Jacobian is 3 to 25 times faster than the fixed-point implicit Runge-Kutta method, and more than 100 times faster than automatic differentiation depending on the grid (size) and the flow problem. The developed methods are fully parallelized with parallel efficiency of 80-90% on the problems tested.

  5. Application of the Jacobian-Free Newton-Krylov Method to Nonlinear Acceleration of Transport Source Iteration in Slab Geometry

    SciTech Connect

    Dana A. Knoll; H. Park; Kord Smith

    2011-02-01

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

  6. Speaker independent acoustic-to-articulatory inversion

    NASA Astrophysics Data System (ADS)

    Ji, An

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

  7. Inverse Floatation

    NASA Astrophysics Data System (ADS)

    Nath, Saurabh; Mukherjee, Anish; Chatterjee, Souvick; Ganguly, Ranjan; Sen, Swarnendu; Mukhopadhyay, Achintya; Boreyko, Jonathan

    2014-11-01

    We have observed that capillarity forces may cause floatation in a few non-intuitive configurations. These may be divided into 2 categories: i) floatation of heavier liquid droplets on lighter immiscible ones and ii) fully submerged floatation of lighter liquid droplets in a heavier immiscible medium. We call these counter-intuitive because of the inverse floatation configuration. For case (i) we have identified and studied in detail the several factors affecting the shape and maximum volume of the floating drop. We used water and vegetable oil combinations as test fluids and established the relation between Bond Number and maximum volume contained in a floating drop (in the order of μL). For case (ii), we injected vegetable oil drop-wise into a pool of water. The fully submerged configuration of the drop is not stable and a slight perturbation to the system causes the droplet to burst and float in partially submerged condition. Temporal variation of a characteristic length of the droplet is analyzed using MATLAB image processing. The constraint of small Bond Number establishes the assumption of lubrication regime in the thin gap. A brief theoretical formulation also shows the temporal variation of the gap thickness. Jadavpur University, Jagadis Bose Centre of Excellence, Virginia Tech.

  8. A KBE tool for solving the mechanisms kinematics

    NASA Astrophysics Data System (ADS)

    Rusu, C.; Tiuca, T. L.; Noveanu, S.; Mândru, D.

    2016-08-01

    Knowledge-Based-Engineering (KBE) is a research field in which the methodologies and technologies for capturing and re-using the engineering knowledge are studied. Nowadays, the mechanisms design is accomplished by using various CAD software. Since, every CAD system includes KBE tools, those can be used to reduce time and simplify the mechanism's design process.One step in the design of the mechanisms with more than one degree of freedom is the direct and inverse kinematic analysis. This step can be difficult, because many calculations are involved and usually more than one solution exists. The geometrical constraints defined in the CAD system for the mechanism linkage's assembling, offer a simple solution for the kinematics analysis.This paper presents a KBE tool useful for kinematics analysis.The automation of repetitive tasks is implemented in an external application written in C# that it is also presented.

  9. Parallel Kinematic Machines (PKM)

    SciTech Connect

    Henry, R.S.

    2000-03-17

    The purpose of this 3-year cooperative research project was to develop a parallel kinematic machining (PKM) capability for complex parts that normally require expensive multiple setups on conventional orthogonal machine tools. This non-conventional, non-orthogonal machining approach is based on a 6-axis positioning system commonly referred to as a hexapod. Sandia National Laboratories/New Mexico (SNL/NM) was the lead site responsible for a multitude of projects that defined the machining parameters and detailed the metrology of the hexapod. The role of the Kansas City Plant (KCP) in this project was limited to evaluating the application of this unique technology to production applications.

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

    SciTech Connect

    Gary D. Egbert

    2007-03-22

    The project covered by this report focused on development of efficient but robust non-linear inversion algorithms for electromagnetic induction data, in particular for data collected with multiple receivers, and multiple transmitters, a situation extremely common in eophysical EM subsurface imaging methods. A key observation is that for such multi-transmitter problems each step in commonly used linearized iterative limited memory search schemes such as conjugate gradients (CG) requires solution of forward and adjoint EM problems for each of the N frequencies or sources, essentially generating data sensitivities for an N dimensional data-subspace. These multiple sensitivities allow a good approximation to the full Jacobian of the data mapping to be built up in many fewer search steps than would be required by application of textbook optimization methods, which take no account of the multiplicity of forward problems that must be solved for each search step. We have applied this idea to a develop a hybrid inversion scheme that combines features of the iterative limited memory type methods with a Newton-type approach using a partial calculation of the Jacobian. Initial tests on 2D problems show that the new approach produces results essentially identical to a Newton type Occam minimum structure inversion, while running more rapidly than an iterative (fixed regularization parameter) CG style inversion. Memory requirements, while greater than for something like CG, are modest enough that even in 3D the scheme should allow 3D inverse problems to be solved on a common desktop PC, at least for modest (~ 100 sites, 15-20 frequencies) data sets. A secondary focus of the research has been development of a modular system for EM inversion, using an object oriented approach. This system has proven useful for more rapid prototyping of inversion algorithms, in particular allowing initial development and testing to be conducted with two-dimensional example problems, before

  11. Kinematics of Strong Discontinuities

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  12. ERENA: A fast and robust Jacobian-free integration method for ordinary differential equations of chemical kinetics

    NASA Astrophysics Data System (ADS)

    Morii, Youhi; Terashima, Hiroshi; Koshi, Mitsuo; Shimizu, Taro; Shima, Eiji

    2016-10-01

    We herein propose a fast and robust Jacobian-free time integration method named as the extended robustness-enhanced numerical algorithm (ERENA) to treat the stiff ordinary differential equations (ODEs) of chemical kinetics. The formulation of ERENA is based on an exact solution of a quasi-steady-state approximation that is optimized to preserve the mass conservation law through use of a Lagrange multiplier method. ERENA exhibits higher accuracy and faster performance in homogeneous ignition simulations compared to existing popular explicit and implicit methods for stiff ODEs such as VODE, MTS, and CHEMEQ2. We investigate the effects of user-specified threshold values in ERENA, to provide trade-off information between the accuracy and the computational cost.

  13. Numerical implementation, verification and validation of two-phase flow four-equation drift flux model with Jacobian-free Newton–Krylov method

    DOE PAGES

    Zou, Ling; Zhao, Haihua; Zhang, Hongbin

    2016-08-24

    This study presents a numerical investigation on using the Jacobian-free Newton–Krylov (JFNK) method to solve the two-phase flow four-equation drift flux model with realistic constitutive correlations (‘closure models’). The drift flux model is based on Isshi and his collaborators’ work. Additional constitutive correlations for vertical channel flow, such as two-phase flow pressure drop, flow regime map, wall boiling and interfacial heat transfer models, were taken from the RELAP5-3D Code Manual and included to complete the model. The staggered grid finite volume method and fully implicit backward Euler method was used for the spatial discretization and time integration schemes, respectively. Themore » Jacobian-free Newton–Krylov method shows no difficulty in solving the two-phase flow drift flux model with a discrete flow regime map. In addition to the Jacobian-free approach, the preconditioning matrix is obtained by using the default finite differencing method provided in the PETSc package, and consequently the labor-intensive implementation of complex analytical Jacobian matrix is avoided. Extensive and successful numerical verification and validation have been performed to prove the correct implementation of the models and methods. Code-to-code comparison with RELAP5-3D has further demonstrated the successful implementation of the drift flux model.« less

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

    USGS Publications Warehouse

    Lee, Myung W.

    2002-01-01

    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.

  15. Robust Inversion and Data Compression in Control Allocation

    NASA Technical Reports Server (NTRS)

    Hodel, A. Scottedward

    2000-01-01

    We present an off-line computational method for control allocation design. The control allocation function delta = F(z)tau = delta (sub 0) (z) mapping commanded body-frame torques to actuator commands is implicitly specified by trim condition delta (sub 0) (z) and by a robust pseudo-inverse problem double vertical line I - G(z) F(z) double vertical line less than epsilon (z) where G(z) is a system Jacobian evaluated at operating point z, z circumflex is an estimate of z, and epsilon (z) less than 1 is a specified error tolerance. The allocation function F(z) = sigma (sub i) psi (z) F (sub i) is computed using a heuristic technique for selecting wavelet basis functions psi and a constrained least-squares criterion for selecting the allocation matrices F (sub i). The method is applied to entry trajectory control allocation for a reusable launch vehicle (X-33).

  16. Kinematically Detected Halo Streams

    NASA Astrophysics Data System (ADS)

    Smith, Martin C.

    Clues to the origins and evolution of our Galaxy can be found in the kinematics of stars around us. Remnants of accreted satellite galaxies produce over-densities in velocity-space, which can remain coherent for much longer than spatial over-densities. This chapter reviews a number of studies that have hunted for these accretion relics, both in the nearby solar-neighborhood and the more-distant stellar halo. Many observational surveys have driven this field forwards, from early work with the Hipparcos mission, to contemporary surveys like RAVE and SDSS. This active field continues to flourish, providing many new discoveries, and will be revolutionized as the Gaia mission delivers precise proper motions for a billion stars in our Galaxy.

  17. O-star kinematics

    SciTech Connect

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

    1984-01-01

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

  18. 3-dimensional magnetotelluric inversion including topography using deformed hexahedral edge finite elements and direct solvers parallelized on symmetric multiprocessor computers - Part II: direct data-space inverse solution

    NASA Astrophysics Data System (ADS)

    Kordy, M.; Wannamaker, P.; Maris, V.; Cherkaev, E.; Hill, G.

    2016-01-01

    Following the creation described in Part I of a deformable edge finite-element simulator for 3-D magnetotelluric (MT) responses using direct solvers, in Part II we develop an algorithm named HexMT for 3-D regularized inversion of MT data including topography. Direct solvers parallelized on large-RAM, symmetric multiprocessor (SMP) workstations are used also for the Gauss-Newton model update. By exploiting the data-space approach, the computational cost of the model update becomes much less in both time and computer memory than the cost of the forward simulation. In order to regularize using the second norm of the gradient, we factor the matrix related to the regularization term and apply its inverse to the Jacobian, which is done using the MKL PARDISO library. For dense matrix multiplication and factorization related to the model update, we use the PLASMA library which shows very good scalability across processor cores. A synthetic test inversion using a simple hill model shows that including topography can be important; in this case depression of the electric field by the hill can cause false conductors at depth or mask the presence of resistive structure. With a simple model of two buried bricks, a uniform spatial weighting for the norm of model smoothing recovered more accurate locations for the tomographic images compared to weightings which were a function of parameter Jacobians. We implement joint inversion for static distortion matrices tested using the Dublin secret model 2, for which we are able to reduce nRMS to ˜1.1 while avoiding oscillatory convergence. Finally we test the code on field data by inverting full impedance and tipper MT responses collected around Mount St Helens in the Cascade volcanic chain. Among several prominent structures, the north-south trending, eruption-controlling shear zone is clearly imaged in the inversion.

  19. Rattlesnake strike behavior: kinematics

    PubMed

    Kardong; v

    1998-03-01

    The predatory behavior of rattlesnakes includes many distinctive preparatory phases leading to an extremely rapid strike, during which venom is injected. The rodent prey is then rapidly released, removing the snake's head from retaliation by the prey. The quick action of the venom makes possible the recovery of the dispatched prey during the ensuing poststrike period. The strike is usually completed in less than 0.5 s, placing a premium on an accurate strike that produces no significant errors in fang placement that could result in poor envenomation and subsequent loss of the prey. To clarify the basis for effective strike performance, we examined the basic kinematics of the rapid strike using high-speed film analysis. We scored numerous strike variables. Four major results were obtained. (1) Neurosensory control of the strike is based primarily upon sensory inputs via the eyes and facial pits to launch the strike, and upon tactile stimuli after contact. Correction for errors in targeting occurs not by a change in strike trajectory, but by fang repositioning after the jaws have made contact with the prey. (2) The rattlesnake strike is based upon great versatility and variation in recruitment of body segments and body postures. (3) Forces generated during acceleration of the head are transferred to posterior body sections to decelerate the head before contact with the prey, thereby reducing impact forces upon the snake's jaws. (4) Body acceleration is based on two patterns of body displacement, one in which acute sections of the body open like a gate, the other in which body segments flow around postural curves similar to movements seen during locomotion. There is one major implication of these results: recruitment of body segments, launch postures and kinematic features of the strike may be quite varied from strike to strike, but the overall predatory success of each strike by a rattlesnake is very consistent.

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    Design of a parallel force-reflecting hand controller that implements a friction- and inertia canceling control loop about the entire mechanism based on wrench sensing in the mechanism handgrip is discussed. Kinematics of the controller under consideration is analyzed and results are presented using a closed-form solution for the inverse kinematics and Newton-Raphson's method for the forward kinematics. Results indicate that the force control scheme based on a handgrip force sensor provides smaller steady-state errors than the scheme without a handigrip sensor.

  1. Detailed solution to a complex kinematics chain manipulator

    SciTech Connect

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

    1992-01-01

    This paper presents a relatively simple method based on planar geometry to analyze the inverse kinematics for closed kinematics chain (CKC) mechanisms. Although the general problem and method of approach are well defined, the study of the inverse kinematics of a closed-chain mechanism is a very complicated one. The current methodology allows closed-form solutions to be found, if a solution exists, for the displacements and velocities of all manipulator joints. Critical design parameters can be identified and optimized by using symbolic models. This paper will focus on planar closed-chain structures extended with a rotational base. However, with open and CKC mechanisms combined in different planes, the extension to the case is straightforward. Further, real-time algorithms are developed that can be handled by existing microprocessor technology. To clarify the methodology, the Soldier Robot Interface Project (SRIP) manipulator is analyzed, and a graphic simulation is presented as a verification of the results. This manipulator has 17 links, 24 one-degree-of-freedom (DOF) joints, and 7 CKC loops working in a plane and a rotational base, which determine its 3 DOFs. The SRIP manipulator allows a decoupled linear motion along the vertical or horizontal directions using only one of its linear actuators. The symbolic solution for the inverse kinematics allows optimization to be performed to further decouple the Cartesian motions by changing link lengths of the manipulator. The conclusion achieved by the optimization is that only two link lengths need to be changed to tune the manipulator for a perfect decoupling at each area of the workspace.

  2. Kinematic precision of gear trains

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    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

  3. Kinematic precision of gear trains

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    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.

  4. Tensor networks from kinematic space

    DOE PAGES

    Czech, Bartlomiej; Lamprou, Lampros; McCandlish, Samuel; Sully, James

    2016-07-20

    We point out that the MERA network for the ground state of a 1+1-dimensional conformal field theory has the same structural features as kinematic space — the geometry of CFT intervals. In holographic theories kinematic space becomes identified with the space of bulk geodesics studied in integral geometry. We argue that in these settings MERA is best viewed as a discretization of the space of bulk geodesics rather than of the bulk geometry itself. As a test of this kinematic proposal, we compare the MERA representation of the thermofield-double state with the space of geodesics in the two-sided BTZ geometry,more » obtaining a detailed agreement which includes the entwinement sector. In conclusion, we discuss how the kinematic proposal can be extended to excited states by generalizing MERA to a broader class of compression networks.« less

  5. Tensor networks from kinematic space

    NASA Astrophysics Data System (ADS)

    Czech, Bartlomiej; Lamprou, Lampros; McCandlish, Samuel; Sully, James

    2016-07-01

    We point out that the MERA network for the ground state of a 1+1-dimensional conformal field theory has the same structural features as kinematic space — the geometry of CFT intervals. In holographic theories kinematic space becomes identified with the space of bulk geodesics studied in integral geometry. We argue that in these settings MERA is best viewed as a discretization of the space of bulk geodesics rather than of the bulk geometry itself. As a test of this kinematic proposal, we compare the MERA representation of the thermofield-double state with the space of geodesics in the two-sided BTZ geometry, obtaining a detailed agreement which includes the entwinement sector. We discuss how the kinematic proposal can be extended to excited states by generalizing MERA to a broader class of compression networks.

  6. Aero-optimum hovering kinematics.

    PubMed

    Nabawy, Mostafa R A; Crowther, William J

    2015-08-07

    Hovering flight for flapping wing vehicles requires rapid and relatively complex reciprocating movement of a wing relative to a stationary surrounding fluid. This note develops a compact analytical aero-kinematic model that can be used for optimization of flapping wing kinematics against aerodynamic criteria of effectiveness (maximum lift) and efficiency (minimum power for a given amount of lift). It can also be used to make predictions of required flapping frequency for a given geometry and basic aerodynamic parameters. The kinematic treatment is based on a consolidation of an existing formulation that allows explicit derivation of flapping velocity for complex motions whereas the aerodynamic model is based on existing quasi-steady analysis. The combined aero-kinematic model provides novel explicit analytical expressions for both lift and power of a hovering wing in a compact form that enables exploration of a rich kinematic design space. Good agreement is found between model predictions of flapping frequency and observed results for a number of insects and optimal hovering kinematics identified using the model are consistent with results from studies using higher order computational models. For efficient flight, the flapping angle should vary using a triangular profile in time leading to a constant velocity flapping motion, whereas for maximum effectiveness the shape of variation should be sinusoidal. For both cases the wing pitching motion should be rectangular such that pitch change at stroke reversal is as rapid as possible.

  7. Aero-optimum hovering kinematics.

    PubMed

    Nabawy, Mostafa R A; Crowther, William J

    2015-08-01

    Hovering flight for flapping wing vehicles requires rapid and relatively complex reciprocating movement of a wing relative to a stationary surrounding fluid. This note develops a compact analytical aero-kinematic model that can be used for optimization of flapping wing kinematics against aerodynamic criteria of effectiveness (maximum lift) and efficiency (minimum power for a given amount of lift). It can also be used to make predictions of required flapping frequency for a given geometry and basic aerodynamic parameters. The kinematic treatment is based on a consolidation of an existing formulation that allows explicit derivation of flapping velocity for complex motions whereas the aerodynamic model is based on existing quasi-steady analysis. The combined aero-kinematic model provides novel explicit analytical expressions for both lift and power of a hovering wing in a compact form that enables exploration of a rich kinematic design space. Good agreement is found between model predictions of flapping frequency and observed results for a number of insects and optimal hovering kinematics identified using the model are consistent with results from studies using higher order computational models. For efficient flight, the flapping angle should vary using a triangular profile in time leading to a constant velocity flapping motion, whereas for maximum effectiveness the shape of variation should be sinusoidal. For both cases the wing pitching motion should be rectangular such that pitch change at stroke reversal is as rapid as possible. PMID:26248884

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

    NASA Technical Reports Server (NTRS)

    Gretz, Bruce; Tilley, Scott W.

    1989-01-01

    The inverse kinematics solution, a modal position control algorithm, and path planning results for a 7 degree of freedom manipulator are presented. The redundant arm consists of two links with shoulder and elbow joints and a spherical wrist. The inverse kinematics problem for tip position is solved and the redundant joint is identified. It is also shown that a locus of tip positions exists in which there are kinematic limitations on self-motion. A computationally simple modal position control algorithm has been developed which guarantees a nearly constant closed-loop dynamic response throughout the workspace. If all closed-loop poles are assigned to the same location, the algorithm can be implemented with very little computation. To further reduce the required computation, the modal gains are updated only at discrete time intervals. Criteria are developed for the frequency of these updates. For commanding manipulator movements, a 5th-order spline which minimizes jerk provides a smooth tip-space path. Schemes for deriving a corresponding joint-space trajectory are discussed. Modifying the trajectory to avoid joint torque saturation when a tip payload is added is also considered. Simulation results are presented.

  9. Kinematic analysis of a flexible six-DOF parallel mechanism.

    PubMed

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

    2006-04-01

    In this paper, a new type of six-degrees of freedom (DOF) flexible parallel mechanism (FPM) is presented. This type of parallel mechanism possesses several favorable properties: (1) its number of DOFs is independent of the number of serial chains which make up the mechanism; (2) it has no kinematical singularities; (3) it is designed to move on rails, and therefore its workspace is much larger than that of a conventional parallel manipulator; and (4) without changing the number of DOFs and the kinematics of the mechanisms, the number of the serial chains can be reconfigured according to the needs of the tasks. These properties make the mechanism very preferable in practice, especially for such tasks as joining huge ship blocks, in which the manipulated objects vary dramatically both in weights and dimensions. Furthermore, the mechanism can be used as either a fully actuated system or an underactuated system. In the fully actuated case, the mechanism has six DOF motion capabilities and manipulation capabilities. However, in the underactuated case, the mechanism still has six DOF motion capabilities, but it has only five DOF manipulation capabilities. In this paper, both the inverse and forward kinematics are studied and expressed in a closed form. The workspace and singularity analysis of the mechanism are also presented. An example is presented to illustrate how to calculate the kinematics of the mechanism in both fully-actuated and underactuated cases. Finally, an application of such a mechanism to manufacturing industry is introduced.

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

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

  12. A Newton-Krylov method with approximate Jacobian for implicit solution of Navier-Stokes on staggered overset-curvilinear grids with immersed boundaries

    NASA Astrophysics Data System (ADS)

    Asgharzadeh, Hafez; Borazjani, Iman

    2014-11-01

    Time step-size restrictions and low convergence rates are major bottle necks for implicit solution of the Navier-Stokes in simulations involving complex geometries with moving boundaries. Newton-Krylov method (NKM) is a combination of a Newton-type method for super-linearly convergent solution of nonlinear equations and Krylov subspace methods for solving the Newton correction equations, which can theoretically address both bottle necks. The efficiency of this method vastly depends on the Jacobian forming scheme e.g. automatic differentiation is very expensive and Jacobian-free methods slow down as the mesh is refined. A novel, computationally efficient analytical Jacobian for NKM was developed to solve unsteady incompressible Navier-Stokes momentum equations on staggered curvilinear grids with immersed boundaries. The NKM was validated and verified against Taylor-Green vortex and pulsatile flow in a 90 degree bend and efficiently handles complex geometries such as an intracranial aneurysm with multiple overset grids, pulsatile inlet flow and immersed boundaries. The NKM method is shown to be more efficient than the semi-implicit Runge-Kutta methods and Jabobian-free Newton-Krylov methods. We believe NKM can be applied to many CFD techniques to decrease the computational cost. This work was supported partly by the NIH Grant R03EB014860, and the computational resources were partly provided by Center for Computational Research (CCR) at University at Buffalo.

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

    NASA Technical Reports Server (NTRS)

    Tahmasebi, Farhad

    2005-01-01

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

  14. A mechanical supination sprain simulator for studying ankle supination sprain kinematics.

    PubMed

    Chan, Yue-Yan; Fong, Daniel Tik-Pui; Yung, Patrick Shu-Hang; Fung, Kwai-Yau; Chan, Kai-Ming

    2008-08-01

    This study presents a free-fall mechanical supination sprain simulator for evaluating the ankle joint kinematics during a simulated ankle supination sprain injury. The device allows the foot to be in an anatomical position before the sudden motion, and also allows different degrees of supination, or a combination of inversion and plantarflexion. Five subjects performed simulated supination sprain trials in five different supination angles. Ankle motion was captured by a motion analysis system, and the ankle kinematics were reported in plantarflexion/dorsiflexion, inversion/eversion and internal/external rotation planes. Results showed that all sprain motions were not pure single-plane motions but were accompanied by motion in other two planes, therefore, different degrees of supination were achieved. The presented sprain simulator allows a more comprehensive study of the kinematics of ankle sprain when compared with some previous laboratory research designs.

  15. Observation of the inverse Doppler effect.

    PubMed

    Seddon, N; Bearpark, T

    2003-11-28

    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.

  16. Visualized kinematics code for two-body nuclear reactions

    NASA Astrophysics Data System (ADS)

    Lee, E. J.; Chae, K. Y.

    2016-05-01

    The one or few nucleon transfer reaction has been a great tool for investigating the single-particle properties of a nucleus. Both stable and exotic beams are utilized to study transfer reactions in normal and inverse kinematics, respectively. Because many energy levels of the heavy recoil from the two-body nuclear reaction can be populated by using a single beam energy, identifying each populated state, which is not often trivial owing to high level-density of the nucleus, is essential. For identification of the energy levels, a visualized kinematics code called VISKIN has been developed by utilizing the Java programming language. The development procedure, usage, and application of the VISKIN is reported.

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

    SciTech Connect

    Christensen, Gary E.; Song, Joo Hyun; Lu, Wei; Naqa, Issam El; Low, Daniel A.

    2007-06-15

    Breathing motion is one of the major limiting factors for reducing dose and irradiation of normal tissue for conventional conformal radiotherapy. This paper describes a relationship between tracking lung motion using spirometry data and image registration of consecutive CT image volumes collected from a multislice CT scanner over multiple breathing periods. Temporal CT sequences from 5 individuals were analyzed in this study. The couch was moved from 11 to 14 different positions to image the entire lung. At each couch position, 15 image volumes were collected over approximately 3 breathing periods. It is assumed that the expansion and contraction of lung tissue can be modeled as an elastic material. Furthermore, it is assumed that the deformation of the lung is small over one-fifth of a breathing period and therefore the motion of the lung can be adequately modeled using a small deformation linear elastic model. The small deformation inverse consistent linear elastic image registration algorithm is therefore well suited for this problem and was used to register consecutive image scans. The pointwise expansion and compression of lung tissue was measured by computing the Jacobian of the transformations used to register the images. The logarithm of the Jacobian was computed so that expansion and compression of the lung were scaled equally. The log-Jacobian was computed at each voxel in the volume to produce a map of the local expansion and compression of the lung during the breathing period. These log-Jacobian images demonstrate that the lung does not expand uniformly during the breathing period, but rather expands and contracts locally at different rates during inhalation and exhalation. The log-Jacobian numbers were averaged over a cross section of the lung to produce an estimate of the average expansion or compression from one time point to the next and compared to the air flow rate measured by spirometry. In four out of five individuals, the average log-Jacobian

  18. Inverse anticipating chaos synchronization.

    PubMed

    Shahverdiev, E M; Sivaprakasam, S; Shore, K A

    2002-07-01

    We derive conditions for achieving inverse anticipating synchronization where a driven time-delay chaotic system synchronizes to the inverse future state of the driver. The significance of inverse anticipating chaos in delineating synchronization regimes in time-delay systems is elucidated. The concept is extended to cascaded time-delay systems.

  19. A fast algorithm for parabolic PDE-based inverse problems based on Laplace transforms and flexible Krylov solvers

    SciTech Connect

    Bakhos, Tania; Saibaba, Arvind K.; Kitanidis, Peter K.

    2015-10-15

    We consider the problem of estimating parameters in large-scale weakly nonlinear inverse problems for which the underlying governing equations is a linear, time-dependent, parabolic partial differential equation. A major challenge in solving these inverse problems using Newton-type methods is the computational cost associated with solving the forward problem and with repeated construction of the Jacobian, which represents the sensitivity of the measurements to the unknown parameters. Forming the Jacobian can be prohibitively expensive because it requires repeated solutions of the forward and adjoint time-dependent parabolic partial differential equations corresponding to multiple sources and receivers. We propose an efficient method based on a Laplace transform-based exponential time integrator combined with a flexible Krylov subspace approach to solve the resulting shifted systems of equations efficiently. Our proposed solver speeds up the computation of the forward and adjoint problems, thus yielding significant speedup in total inversion time. We consider an application from Transient Hydraulic Tomography (THT), which is an imaging technique to estimate hydraulic parameters related to the subsurface from pressure measurements obtained by a series of pumping tests. The algorithms discussed are applied to a synthetic example taken from THT to demonstrate the resulting computational gains of this proposed method.

  20. Achieving Finite Element Mesh Quality via Optimization of the Jacobian Matrix Norm and Associated Quantities, Part II - A Framework for Volume Mesh Optimization and the Condition Number of the Jacobian Matrix

    SciTech Connect

    Knupp, P.M.

    1999-03-26

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

  1. Functional kinematics of the wrist.

    PubMed

    Rainbow, M J; Wolff, A L; Crisco, J J; Wolfe, S W

    2016-01-01

    The purpose of this article is to review past and present concepts concerning functional kinematics of the healthy and injured wrist. To provide a context for students of the wrist, we describe the progression of techniques for measuring carpal kinematics over the past century and discuss how this has influenced today's understanding of functional kinematics. Next, we provide an overview of recent developments and highlight the clinical relevance of these findings. We use these findings and recent evidence that supports the importance of coupled motion in early rehabilitation of radiocarpal injuries to develop the argument that coupled motion during functional activities is a clinically relevant outcome; therefore, clinicians should develop a framework for its dynamic assessment. This should enable a tailored and individualized approach to the treatment of carpal injuries.

  2. KINEMATIC ANALYSIS OF MODULAR, TRUSS-BASED MANIPULATOR UNITS

    SciTech Connect

    Salerno, R. J.

    1994-06-01

    solution techniques are developed for solving the "forward" or "direct" and "inverse" kinematic problems for these geometries. The" forward" kinematic problem is that of finding the position and orientation of the distal end of the VGT relative to the proximal end, given the specific displacements of the (linear) actuators. This problem is rarely solvable in closed form. However, powerful iterative algorithms capable of solution in real time on typical modern robot control hardware are presented. The "inverse" kinematic problem is that of finding the required actuator displacements given the position and orientation of the distal end of the VGT relative to the proximal end. For specific VGT geometries, closed-form solutions are presented. For the more general problem, iterative algorithms capable of solution in real time are again derived and presented.

  3. Kinematics of KPG 390

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

    In this work we present scanning Fabry-Perot Hα observations of the isolated interacting galaxy pair NGC 5278/9 obtained with the PUMA Fabry-Perot interferometer. We derived velocity fields, various kinematic parameters and rotation curves for both galaxies. Our kinematical results together with the fact that dust lanes have been detected in both galaxies, as well as the analysis of surface brightness profiles along the minor axis, allowed us to determine that both components of the interacting pair are trailing spirals.

  4. Occupant Kinematics in Laboratory Rollover Tests: PMHS Response.

    PubMed

    Lessley, David J; Riley, Patrick; Zhang, Qi; Foltz, Patrick; Overby, Brian; Heltzel, Sara; Sochor, Mark; Crandall, Jeff; Kerrigan, Jason R

    2014-11-01

    The objective of the current study was to characterize the whole-body kinematic response of restrained PMHS in controlled laboratory rollover tests. A dynamic rollover test system (DRoTS) and a parametric vehicle buck were used to conduct 36 rollover tests on four adult male PMHS with varied test conditions to study occupant kinematics during the rollover event. The DRoTS was used to drop/catch and rotate the test buck, which replicated the occupant compartment of a typical mid-sized SUV, around its center of gravity without roof-to-ground contact. The studied test conditions included a quasi-static inversion (4 tests), an inverted drop and catch that produced a 3 g vertical deceleration (4 tests), a pure dynamic roll at 360 degrees/second (11 tests), and a roll with a superimposed drop and catch produced vertical deceleration (17 tests). Each PMHS was restrained with a three-point belt and was tested in both leading-side and trailing-side front-row seating positions. Whole-body kinematics were measured using a 3D motion capture system that quantified occupant displacement relative to the vehicle buck for the X-axis (longitudinal), Y-axis (lateral), and Z-axis (vertical) directions. Additionally the spine was divided into five segments to describe intrasegmental kinematics of the spine, including segment rotations as well as spinal extension and compression. The reported data represent the most complete set of kinematic response targets for a restrained occupant in a variety of dynamic rollover conditions, and are immediately useful for efforts to evaluate and improve existing ATDs and computational models for use in the rollover crash environment.

  5. Occupant Kinematics in Laboratory Rollover Tests: PMHS Response.

    PubMed

    Lessley, David J; Riley, Patrick; Zhang, Qi; Foltz, Patrick; Overby, Brian; Heltzel, Sara; Sochor, Mark; Crandall, Jeff; Kerrigan, Jason R

    2014-11-01

    The objective of the current study was to characterize the whole-body kinematic response of restrained PMHS in controlled laboratory rollover tests. A dynamic rollover test system (DRoTS) and a parametric vehicle buck were used to conduct 36 rollover tests on four adult male PMHS with varied test conditions to study occupant kinematics during the rollover event. The DRoTS was used to drop/catch and rotate the test buck, which replicated the occupant compartment of a typical mid-sized SUV, around its center of gravity without roof-to-ground contact. The studied test conditions included a quasi-static inversion (4 tests), an inverted drop and catch that produced a 3 g vertical deceleration (4 tests), a pure dynamic roll at 360 degrees/second (11 tests), and a roll with a superimposed drop and catch produced vertical deceleration (17 tests). Each PMHS was restrained with a three-point belt and was tested in both leading-side and trailing-side front-row seating positions. Whole-body kinematics were measured using a 3D motion capture system that quantified occupant displacement relative to the vehicle buck for the X-axis (longitudinal), Y-axis (lateral), and Z-axis (vertical) directions. Additionally the spine was divided into five segments to describe intrasegmental kinematics of the spine, including segment rotations as well as spinal extension and compression. The reported data represent the most complete set of kinematic response targets for a restrained occupant in a variety of dynamic rollover conditions, and are immediately useful for efforts to evaluate and improve existing ATDs and computational models for use in the rollover crash environment. PMID:26192958

  6. Kinematic performance analysis of a parallel-chain hexapod machine

    SciTech Connect

    Jing Song; Jong-I Mou; Calvin King

    1998-05-18

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

  7. Top quark mass and kinematics

    SciTech Connect

    Barberis, Emanuela; /Northeastern U.

    2006-05-01

    A summary of the results on the measurement of the Top Quark mass and the study of the kinematics of the t{bar t} system at the Tevatron collider is presented here. Results from both the CDF and D0 collaborations are reported.

  8. Kinematic Parameters of Signed Verbs

    ERIC Educational Resources Information Center

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

    2013-01-01

    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…

  9. Kinematics and dynamics of robotic systems with multiple closed loops

    NASA Astrophysics Data System (ADS)

    Zhang, Chang-De

    The kinematics and dynamics of robotic systems with multiple closed loops, such as Stewart platforms, walking machines, and hybrid manipulators, are studied. In the study of kinematics, focus is on the closed-form solutions of the forward position analysis of different parallel systems. A closed-form solution means that the solution is expressed as a polynomial in one variable. If the order of the polynomial is less than or equal to four, the solution has analytical closed-form. First, the conditions of obtaining analytical closed-form solutions are studied. For a Stewart platform, the condition is found to be that one rotational degree of freedom of the output link is decoupled from the other five. Based on this condition, a class of Stewart platforms which has analytical closed-form solution is formulated. Conditions of analytical closed-form solution for other parallel systems are also studied. Closed-form solutions of forward kinematics for walking machines and multi-fingered grippers are then studied. For a parallel system with three three-degree-of-freedom subchains, there are 84 possible ways to select six independent joints among nine joints. These 84 ways can be classified into three categories: Category 3:3:0, Category 3:2:1, and Category 2:2:2. It is shown that the first category has no solutions; the solutions of the second category have analytical closed-form; and the solutions of the last category are higher order polynomials. The study is then extended to a nearly general Stewart platform. The solution is a 20th order polynomial and the Stewart platform has a maximum of 40 possible configurations. Also, the study is extended to a new class of hybrid manipulators which consists of two serially connected parallel mechanisms. In the study of dynamics, a computationally efficient method for inverse dynamics of manipulators based on the virtual work principle is developed. Although this method is comparable with the recursive Newton-Euler method for

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

    NASA Technical Reports Server (NTRS)

    Nguyen, Charles C.; Pooran, Farhad J.

    1989-01-01

    This report presents results from the research grant entitled Active Control of Robot Manipulators, funded by the Goddard Space Flight Center, under Grant NAG5-780, for the period July 1, 1988 to January 1, 1989. An analysis is presented of a 6 degree-of-freedom robot end-effector built to study telerobotic assembly of NASA hardware in space. Since the end-effector is required to perform high precision motion in a limited workspace, closed-kinematic mechanisms are chosen for its design. A closed-form solution is obtained for the inverse kinematic problem and an iterative procedure employing Newton-Raphson method is proposed to solve the forward kinematic problem. A study of the end-effector workspace results in a general procedure for the workspace determination based on link constraints. Computer simulation results are presented.

  11. Analysis of a closed-kinematic chain robot manipulator

    NASA Technical Reports Server (NTRS)

    Nguyen, Charles C.; Pooran, Farhad J.

    1988-01-01

    Presented are the research results from the research grant entitled: Active Control of Robot Manipulators, sponsored by the Goddard Space Flight Center (NASA) under grant number NAG-780. This report considers a class of robot manipulators based on the closed-kinematic chain mechanism (CKCM). This type of robot manipulators mainly consists of two platforms, one is stationary and the other moving, and they are coupled together through a number of in-parallel actuators. Using spatial geometry and homogeneous transformation, a closed-form solution is derived for the inverse kinematic problem of the six-degree-of-freedom manipulator, built to study robotic assembly in space. Iterative Newton Raphson method is employed to solve the forward kinematic problem. Finally, the equations of motion of the above manipulators are obtained by employing the Lagrangian method. Study of the manipulator dynamics is performed using computer simulation whose results show that the robot actuating forces are strongly dependent on the mass and centroid locations of the robot links.

  12. Kinematic and stability motion limits for a hexapod walking machine

    NASA Astrophysics Data System (ADS)

    Dunton, Elizabeth M.

    1995-03-01

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

  13. Three-dimensional magnetotelluric inversion including topography using deformed hexahedral edge finite elements, direct solvers and data space Gauss-Newton, parallelized on SMP computers

    NASA Astrophysics Data System (ADS)

    Kordy, M. A.; Wannamaker, P. E.; Maris, V.; Cherkaev, E.; Hill, G. J.

    2014-12-01

    We have developed an algorithm for 3D simulation and inversion of magnetotelluric (MT) responses using deformable hexahedral finite elements that permits incorporation of topography. Direct solvers parallelized on symmetric multiprocessor (SMP), single-chassis workstations with large RAM are used for the forward solution, parameter jacobians, and model update. The forward simulator, jacobians calculations, as well as synthetic and real data inversion are presented. We use first-order edge elements to represent the secondary electric field (E), yielding accuracy O(h) for E and its curl (magnetic field). For very low frequency or small material admittivity, the E-field requires divergence correction. Using Hodge decomposition, correction may be applied after the forward solution is calculated. It allows accurate E-field solutions in dielectric air. The system matrix factorization is computed using the MUMPS library, which shows moderately good scalability through 12 processor cores but limited gains beyond that. The factored matrix is used to calculate the forward response as well as the jacobians of field and MT responses using the reciprocity theorem. Comparison with other codes demonstrates accuracy of our forward calculations. We consider a popular conductive/resistive double brick structure and several topographic models. In particular, the ability of finite elements to represent smooth topographic slopes permits accurate simulation of refraction of electromagnetic waves normal to the slopes at high frequencies. Run time tests indicate that for meshes as large as 150x150x60 elements, MT forward response and jacobians can be calculated in ~2.5 hours per frequency. For inversion, we implemented data space Gauss-Newton method, which offers reduction in memory requirement and a significant speedup of the parameter step versus model space approach. For dense matrix operations we use tiling approach of PLASMA library, which shows very good scalability. In synthetic

  14. The Stellar Kinematics of Several Irregular Galaxies

    NASA Astrophysics Data System (ADS)

    Hunter, D. A.; Rubin, V. C.; Swaters, R. A.

    2001-12-01

    We present long-slit spectra of three irregular galaxies from which we determine the stellar kinematics in two of the galaxies (NGC 1156 and NGC 4449) and ionized-gas kinematics in all three (including NGC 2366). We compare the stellar and ionized gas kinematics to the morphology of the galaxies and their HI kinematics. We find surprising differences between the kinematics of the stars, ionized gas, and neutral gas in these systems. Support for this work was provided to DAH by the Lowell Research Fund and by the National Science Foundation through grant AST-9616940.

  15. Exploring MaNGA's kinematic maps

    NASA Astrophysics Data System (ADS)

    Weijmans, Anne-Marie; MaNGA Team

    2016-01-01

    Different galaxy formation processes leave different imprints on the gas and stellar kinematic patterns for a galaxy. With MaNGA, we now have after one year of observations an unprecedented sample of 1400 nearby galaxies for which we can study gas and stellar kinematics in much detail, based on integral-field spectroscopy. We are measuring kinematic quantities such as LambdaR (angular momentum) and their (possible) correlations with other galaxy properties such as mass, morphology and environment. By quantifying the kinematic (sub)structures in velocity and dispersion maps, we will construct a kinematic galaxy classification that can be linked to their formation processes.

  16. Inversion of high frequency surface waves with fundamental and higher modes

    USGS Publications Warehouse

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

    2003-01-01

    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.

  17. Seismic Inversion Methods

    NASA Astrophysics Data System (ADS)

    Jackiewicz, Jason

    2009-09-01

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

  18. Seismic Inversion Methods

    SciTech Connect

    Jackiewicz, Jason

    2009-09-16

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

  19. A ''Voice Inversion Effect?''

    ERIC Educational Resources Information Center

    Bedard, Catherine; Belin, Pascal

    2004-01-01

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

  20. Kinematic Fitting of Detached Vertices

    SciTech Connect

    Mattione, Paul

    2007-05-01

    The eg3 experiment at the Jefferson Lab CLAS detector aims to determine the existence of the $\\Xi_{5}$ pentaquarks and investigate the excited $\\Xi$ states. Specifically, the exotic $\\Xi_{5}^{--}$ pentaquark will be sought by first reconstructing the $\\Xi^{-}$ particle through its weak decays, $\\Xi^{-}\\to\\pi^{-}\\Lambda$ and $\\Lambda\\to\\pi^{-}$. A kinematic fitting routine was developed to reconstruct the detached vertices of these decays, where confidence level cuts on the fits are used to remove background events. Prior to fitting these decays, the exclusive reaction $\\gamma D\\rightarrow pp\\pi^{-}$ was studied in order to correct the track measurements and covariance matrices of the charged particles. The $\\Lambda\\rightarrow p\\pi^{-}$ and $\\Xi^{-}\\to\\pi^{-}\\Lambda$ decays were then investigated to demonstrate that the kinematic fitting routine reconstructs the decaying particles and their detached vertices correctly.

  1. Pythagoras Theorem and Relativistic Kinematics

    NASA Astrophysics Data System (ADS)

    Mulaj, Zenun; Dhoqina, Polikron

    2010-01-01

    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.

  2. Of cilium and flagellum kinematics

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, Promode R.; Hansen, Joshua C.

    2009-11-01

    The kinematics of propulsion of small animals such as paramecium and spermatozoa is considered. Larger scale models of the cilium and flagellum have been built and a four-motor apparatus has been constructed to reproduce their known periodic motions. The cilium model has transverse deformational ability in one plane only, while the flagellum model has such ability in two planes. When the flagellum model is given a push-pull in one diametral plane, instead of transverse deflection in one plane, it forms a coil. Berg & Anderson's postulation (Nature 245 1973) that a flagellum rotates, is recalled. The kinematics of cilia of paramecium, of the whipping motion of the spermatozoa flagella, and of the flapping motion (rolling and pitching) of the pectoral fins of much larger animals such penguins, have been reproduced in the same basic paramecium apparatus. The results suggest that each of the tiny individual paramecium propulsors have the intrinsic dormant kinematic and structural building blocks to optimize into higher Reynolds number propulsors. A synthetic hypothesis on how small might have become large is animated.

  3. Kinematic Characterization of Left Ventricular Chamber Stiffness and Relaxation

    NASA Astrophysics Data System (ADS)

    Mossahebi, Sina

    Heart failure is the most common cause of hospitalization today, and diastolic heart failure accounts for 40-50% of cases. Therefore, it is critical to identify diastolic dysfunction at a subclinical stage so that appropriate therapy can be administered before ventricular function is further, and perhaps irreversibly impaired. Basic concepts in physics such as kinematic modeling provide a unique method with which to characterize cardiovascular physiology, specifically diastolic function (DF). The advantage of an approach that is standard in physics, such as the kinematic modeling is its causal formulation that functions in contrast to correlative approaches traditionally utilized in the life sciences. Our research group has pioneered theoretical and experimental quantitative analysis of DF in humans, using both non-invasive (echocardiography, cardiac MRI) and invasive (simultaneous catheterization-echocardiography) methods. Our group developed and validated the Parametrized Diastolic Filling (PDF) formalism which is motivated by basic physiologic principles (LV is a mechanical suction pump at the mitral valve opening) that obey Newton's Laws. PDF formalism is a kinematic model of filling employing an equation of motion, the solution of which accurately predicts all E-wave contours in accordance with the rules of damped harmonic oscillatory motion. The equation's lumped parameters---ventricular stiffness, ventricular viscoelasticity/relaxation and ventricular load---are obtained by solving the 'inverse problem'. The parameters' physiologic significance and clinical utility have been repeatedly demonstrated in multiple clinical settings. In this work we apply our kinematic modeling approach to better understand how the heart works as it fills in order to advance the relationship between physiology and mathematical modeling. Through the use of this modeling, we thereby define and validate novel, causal indexes of diastolic function such as early rapid filling energy

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  5. Solar inverse theory

    NASA Astrophysics Data System (ADS)

    Gough, D.

    1984-12-01

    Helioseismological inversion, as with the inversion of any other data, is divided into three phases. The first is the solution of the so-called forward problem: namely, the calculation of the eigenfrequencies of a theoretical equilibrium state. The second is an attempt to understand the results, either empirically by determining how those frequencies vary as chosen parameters defining the equilibrium model are varied, or analytically from asymptotic expansions in limiting cases of high order or degree. The third phase is to pose and solve an inverse problem, which seeks to find a plausible equilibrium model of the Sun whose eigenfrequencies are consistent with observation. The three phases are briefly discussed in this review, and the third, which is not yet widely used in helioseismology, is illustrated with some selected inversions of artificial solar data.

  6. Pseudo-Rigid-Body Model and Kinematic Analysis of MRI-Actuated Catheters

    PubMed Central

    Greigarn, Tipakorn; Çavuşoğlu, M. Cenk

    2015-01-01

    This paper presents a kinematic study of a pseudorigid-body model (PRBM) of MRI-compatible, magnetically actuated, steerable catheters. It includes a derivation of a mathematical model of the PRBM of the catheter, singularity studies of the model, and a new manipulability measure. While the forward kinematics of the model presented here is applicable to PRBMs for other applications, actuation method is unique to the particular design. Hence, a careful study of singularities and manipulability of the model is required. The singularities are studied from the underlying equations of motion with intuitive interpretations. The proposed manipulability measure is a generalization of the inverse condition number manipulability measure of robotic manipulators. While the PRBM is an approximation of the flexible catheter, kinematic studies of the PRBM still provide some insight into feasibility and limitations of the catheter, which is beneficial to the design and motion planning of the catheter. PMID:26413380

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

    PubMed

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

    2014-04-01

    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 μrad and 0.25 μrad.

  8. Kinematic Analysis and Synthesis of a 3-URU Pure Rotational Parallel Mechanism with Respect to Singularity and Workspace

    NASA Astrophysics Data System (ADS)

    Huda, Syamsul; Takeda, Yukio

    This paper concerns kinematics and dimensional synthesis of a three universal-revolute-universal (3-URU) pure rotational parallel mechanism. The mechanism is composed of a base, a platform and three symmetric limbs consisting of U-R-U joints. This mechanism is a spatial non-overconstrained mechanism with three degrees of freedom. The joints in each limb are so arranged to perform pure rotational motion of the platform around a specific point. Equations for inverse displacement analysis and singularities were derived to investigate the relationship of the kinematic constants to the solution of the inverse kinematics and singularities. Based on the results, a dimensional synthesis procedure for the 3-URU parallel mechanism considering singularities and the workspace was proposed. A numerical example was also presented to illustrate the synthesis method.

  9. Generalized emissivity inverse problem.

    PubMed

    Ming, DengMing; Wen, Tao; Dai, XianXi; Dai, JiXin; Evenson, William E

    2002-04-01

    Inverse problems have recently drawn considerable attention from the physics community due to of potential widespread applications [K. Chadan and P. C. Sabatier, Inverse Problems in Quantum Scattering Theory, 2nd ed. (Springer Verlag, Berlin, 1989)]. An inverse emissivity problem that determines the emissivity g(nu) from measurements of only the total radiated power J(T) has recently been studied [Tao Wen, DengMing Ming, Xianxi Dai, Jixin Dai, and William E. Evenson, Phys. Rev. E 63, 045601(R) (2001)]. In this paper, a new type of generalized emissivity and transmissivity inverse (GETI) problem is proposed. The present problem differs from our previous work on inverse problems by allowing the unknown (emissivity) function g(nu) to be temperature dependent as well as frequency dependent. Based on published experimental information, we have developed an exact solution formula for this GETI problem. A universal function set suggested for numerical calculation is shown to be robust, making this inversion method practical and convenient for realistic calculations.

  10. The inverse electroencephalography pipeline

    NASA Astrophysics Data System (ADS)

    Weinstein, David Michael

    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.

  11. Direct and indirect inversions

    NASA Astrophysics Data System (ADS)

    Virieux, Jean; Brossier, Romain; Métivier, Ludovic; Operto, Stéphane; Ribodetti, Alessandra

    2016-06-01

    A bridge is highlighted between the direct inversion and the indirect inversion. They are based on fundamental different approaches: one is looking after a projection from the data space to the model space while the other one is reducing a misfit between observed data and synthetic data obtained from a given model. However, it is possible to obtain similar structures for model perturbation, and we shall focus on P-wave velocity reconstruction. This bridge is built up through the Born approximation linearizing the forward problem with respect to model perturbation and through asymptotic approximations of the Green functions of the wave propagation equation. We first describe the direct inversion and its ingredients and then we focus on a specific misfit function design leading to a indirect inversion. Finally, we shall compare this indirect inversion with more standard least-squares inversion as the FWI, enabling the focus on small weak velocity perturbations on one side and the speed-up of the velocity perturbation reconstruction on the other side. This bridge has been proposed by the group led by Raul Madariaga in the early nineties, emphasizing his leading role in efficient imaging workflows for seismic velocity reconstruction, a drastic requirement at that time.

  12. Kinematic correction for roller skewing

    NASA Technical Reports Server (NTRS)

    Savage, M.; Loewenthal, S. H.

    1980-01-01

    A theory of kinematic stabilization of rolling cylinders is developed for high-speed cylindrical roller bearings. This stabilization requires race and roller crowning to product changes in the rolling geometry as the roller shifts axially. These changes put a reverse skew in the rolling elements by changing the rolling taper. Twelve basic possible bearing modifications are identified in this paper. Four have single transverse convex curvature in the rollers while eight have rollers with compound transverse curvature composed of a central cylindrical band of constant radius surrounded by symmetric bands with both slope and transverse curvature.

  13. Relativistic kinematics and stationary motions

    NASA Astrophysics Data System (ADS)

    Russo, Jorge G.; Townsend, Paul K.

    2009-11-01

    The relativistic jerk, snap and all higher-order kinematical D-vectors are defined for the motion of a massive particle in a D-dimensional Minkowski spacetime. We illustrate the formalism with stationary motions, for which we provide a new, Lorentz covariant, classification. We generalize some cases to branes, explaining the relevance to uniform motion in a heat bath. We also consider some non-stationary motions, including motion with constant proper jerk, and free fall into a black hole as viewed from a GEMS perspective.

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

    NASA Technical Reports Server (NTRS)

    Jorgensen, Charles C.

    1990-01-01

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

  15. Basic concepts of kinematic-wave models

    USGS Publications Warehouse

    Miller, J.E.

    1984-01-01

    The kinematic-wave model is one of a number of approximations of the dynamic-wave model. The dynamic-wave model describes one-dimensional shallow-water waves (unsteady, gradually varied, open-channel flow). The report provides a basic reference on the theory and application of kinematic-wave models and describes the limitations of the model in relation to the other approximations of the dynamic-wave model. In the kinematic-wave approximation, a number of the terms in the equation of motion are assumed to be insignificant. The equation of motion is replaced by an equation describing uniform flow. Thus, the kinematic-wave model is described by the continuity equation and a uniform flow equation such as the well-known Chezy or Manning formulas. Kinematic-wave models are applicable to overland flow where lateral inflow is continuously added and is a large part of the total flow. For channel-routing applications, the kinematic-wave model always predicts a steeper wave with less dispersion and attenuation than actually occurs. The effect of the accumulation of errors in the kinematic-wave model shows that the approximations made in the development of the kinematic-wave equations are not generally justified for most channel-routing applications. Modified flow-routing models can be used which help to stop the accumulation of error that occurs when the kinematic-wave model is applied. (USGS)

  16. Ballistic representation for kinematic access

    NASA Astrophysics Data System (ADS)

    Alfano, Salvatore

    2011-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  18. Kinematics of the free throw in basketball

    NASA Astrophysics Data System (ADS)

    Tan, A.; Miller, G.

    1981-06-01

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

  19. The application of Jacobian-free Newton-Krylov methods to reduce the spin-up time of ocean general circulation models

    SciTech Connect

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

    2010-10-20

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

  20. A Biomechanical Model of the Scapulothoracic Joint to Accurately Capture Scapular Kinematics during Shoulder Movements

    PubMed Central

    Seth, Ajay; Matias, Ricardo; Veloso, António P.; Delp, Scott L.

    2016-01-01

    The complexity of shoulder mechanics combined with the movement of skin relative to the scapula makes it difficult to measure shoulder kinematics with sufficient accuracy to distinguish between symptomatic and asymptomatic individuals. Multibody skeletal models can improve motion capture accuracy by reducing the space of possible joint movements, and models are used widely to improve measurement of lower limb kinematics. In this study, we developed a rigid-body model of a scapulothoracic joint to describe the kinematics of the scapula relative to the thorax. This model describes scapular kinematics with four degrees of freedom: 1) elevation and 2) abduction of the scapula on an ellipsoidal thoracic surface, 3) upward rotation of the scapula normal to the thoracic surface, and 4) internal rotation of the scapula to lift the medial border of the scapula off the surface of the thorax. The surface dimensions and joint axes can be customized to match an individual’s anthropometry. We compared the model to “gold standard” bone-pin kinematics collected during three shoulder tasks and found modeled scapular kinematics to be accurate to within 2mm root-mean-squared error for individual bone-pin markers across all markers and movement tasks. As an additional test, we added random and systematic noise to the bone-pin marker data and found that the model reduced kinematic variability due to noise by 65% compared to Euler angles computed without the model. Our scapulothoracic joint model can be used for inverse and forward dynamics analyses and to compute joint reaction loads. The computational performance of the scapulothoracic joint model is well suited for real-time applications; it is freely available for use with OpenSim 3.2, and is customizable and usable with other OpenSim models. PMID:26734761

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

    USGS Publications Warehouse

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

    2011-01-01

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

  2. Speeding up the learning of robot kinematics through function decomposition.

    PubMed

    Ruiz de Angulo, Vicente; Torras, Carme

    2005-11-01

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

  3. Bayesian kinematic earthquake source models

    NASA Astrophysics Data System (ADS)

    Minson, S. E.; Simons, M.; Beck, J. L.; Genrich, J. F.; Galetzka, J. E.; Chowdhury, F.; Owen, S. E.; Webb, F.; Comte, D.; Glass, B.; Leiva, C.; Ortega, F. H.

    2009-12-01

    Most coseismic, postseismic, and interseismic slip models are based on highly regularized optimizations which yield one solution which satisfies the data given a particular set of regularizing constraints. This regularization hampers our ability to answer basic questions such as whether seismic and aseismic slip overlap or instead rupture separate portions of the fault zone. We present a Bayesian methodology for generating kinematic earthquake source models with a focus on large subduction zone earthquakes. Unlike classical optimization approaches, Bayesian techniques sample the ensemble of all acceptable models presented as an a posteriori probability density function (PDF), and thus we can explore the entire solution space to determine, for example, which model parameters are well determined and which are not, or what is the likelihood that two slip distributions overlap in space. Bayesian sampling also has the advantage that all a priori knowledge of the source process can be used to mold the a posteriori ensemble of models. Although very powerful, Bayesian methods have up to now been of limited use in geophysical modeling because they are only computationally feasible for problems with a small number of free parameters due to what is called the "curse of dimensionality." However, our methodology can successfully sample solution spaces of many hundreds of parameters, which is sufficient to produce finite fault kinematic earthquake models. Our algorithm is a modification of the tempered Markov chain Monte Carlo (tempered MCMC or TMCMC) method. In our algorithm, we sample a "tempered" a posteriori PDF using many MCMC simulations running in parallel and evolutionary computation in which models which fit the data poorly are preferentially eliminated in favor of models which better predict the data. We present results for both synthetic test problems as well as for the 2007 Mw 7.8 Tocopilla, Chile earthquake, the latter of which is constrained by InSAR, local high

  4. Inter-segment foot kinematics during cross-slope running.

    PubMed

    Dixon, Philippe C; Tisseyre, Magali; Damavandi, Mohsen; Pearsall, David J

    2011-04-01

    Cross-slopes are a common terrain characteristic, however there is no biomechanical knowledge of the intra-foot adaptations required for running on these surface inclinations. The purpose of this study was to evaluate the kinematic changes induced within the foot while running on a transversely inclined surface. A three-segment foot model distinguishing between the hindfoot, forefoot, and hallux was used for this purpose. Nine healthy experienced male runners volunteered to perform level (0°) and cross-slope (10°) running trials barefoot at a moderate speed. Multivariate analysis of variance (MANOVA) for repeated measures was used to analyze the kinematics of the hindfoot with respect to tibia (HF/TB), forefoot with respect to hindfoot (FF/HF), and hallux with respect to forefoot (HX/FF) during level running (LR), incline running up-slope (IRU), and incline running down-slope (IRD) conditions. In the sagittal plane, the FF/HF angle showed greater dorsiflexion at peak vertical force production (MaxFz) in IRD compared to LR (p=0.042). The HX/FF was significantly more extended during IRU than LR at foot strike (p=0.027). More importantly, frontal plane asymmetries were also found. HF/TB angles revealed greater inversion at foot strike followed by greater eversion at MaxFz for IRU compared to IRD (p=0.042 and p=0.018, respectively). For the FF/HF angle, maximum eversion was greater during IRD than LR (p=0.035). Data suggests that running on cross-slopes can induce substantial intra-foot kinematic adaptations, whether this represents a risk of injury to both recreational and professional runners remains to be determined.

  5. A Kinematically Consistent Two-Point Correlation Function

    NASA Technical Reports Server (NTRS)

    Ristorcelli, J. R.

    1998-01-01

    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.

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

    SciTech Connect

    Hart, K.A.

    1994-01-01

    During the Intensive Observation Period (IOP), several periods of water vapor and temperature inversions near the 0 deg C level were observed. Satellite and radiosonde data from TOGA COARE are used to document the large-scale conditions and thermodynamic and kinematic structures present during three extended periods in which moisture and temperature inversions near the freezing level were very pronounced. Observations from each case are synthesized into schematics which represent typical structures of the inversion phenomena. Frequency distributions of the inversion phenomena along with climatological humidity and temperature profiles are calculated for the four-month IOP.

  7. Inversion of triton moments

    NASA Astrophysics Data System (ADS)

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

    1981-02-01

    We use the formalism of hyperspherical harmonics to calculate several moments for the triton photoeffect, for a Volkov spin-independent potential. First, we improve the accuracy of Maleki's calculations of the moments σ2 and σ3 by including more terms in the hyperspherical expansion. We also calculate moments σ0 and σ1 for a Serber mixture. We find reasonable agreement between our moments found by sum rules and those found from the cross sections calculated by Fang et al. and Levinger-Fitzgibbon. We then develop a technique of inversion of a finite number of moments by making the assumption that the cross section can be written as a sum of several Laguerre polynomials multiplied by a decreasing exponential. We test our inversion technique successfully on several model potentials. We then modify it and apply it to the five moments (σ-1 to σ3) for a force without exchange, and find fair agreement with Fang's values of the cross section. Finally, we apply the inversion technique to our three moments (σ-1,σ0,and σ1) for a Serber mixture, and find reasonable agreement with Gorbunov's measurements of the 3He photoeffect. NUCLEAR REACTIONS Triton photoeffects, hyperspherical harmonics, moments of photoeffect, inversion of moments.

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

    SciTech Connect

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

    2015-06-12

    Understanding the heterogeneity arising from the complex architecture of sedimentary sequences in alluvial fans is challenging. This study develops a statistical inverse framework in a multi-zone transition probability approach for characterizing the heterogeneity in alluvial fans. An analytical solution of the transition probability matrix is used to define the statistical relationships among different hydrofacies and their mean lengths, integral scales, and volumetric proportions. A statistical inversion is conducted to identify the multi-zone transition probability models and estimate the optimal statistical parameters using the modified Gauss–Newton–Levenberg–Marquardt method. The Jacobian matrix is computed by the sensitivity equation method, which results in an accurate inverse solution with quantification of parameter uncertainty. We use the Chaobai River alluvial fan in the Beijing Plain, China, as an example for elucidating the methodology of alluvial fan characterization. The alluvial fan is divided into three sediment zones. In each zone, the explicit mathematical formulations of the transition probability models are constructed with optimized different integral scales and volumetric proportions. The hydrofacies distributions in the three zones are simulated sequentially by the multi-zone transition probability-based indicator simulations. Finally, the result of this study provides the heterogeneous structure of the alluvial fan for further study of flow and transport simulations.

  9. Inversion of arbitrary segmented loop source TEM data over a layered earth

    NASA Astrophysics Data System (ADS)

    Li, Hai; Xue, Guo-qiang; Zhao, pan; Zhou, Nan-nan; Zhong, Hua-sen

    2016-05-01

    The loop source TEM method has been widely used in the detection of a mined out area in China. In the cases that the laying of traditional rectangle or square transmitting loop is limited due to the presence of obstacle on the path of the loop, the changing of the shape of the transmitting loop to bypass the obstacle is a labor saving solution. A numeric integration scheme is proposed to calculate the response and Jacobian of the segmented loop source from that of an electric dipole source. The comparison of forward response between the segmented loop and square loop shows the effect of loop geometry on the decay curves. In order to interpret the data from an irregular source loop, this paper presents an inversion scheme that incorporate the effect of loop geometry. The proposed inversion scheme is validated on the synthetic data, and then applied to the field data. The result reveals that the developed inversion scheme is capable of interpreting the segmented loop source TEM field data.

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

    DOE PAGES

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

    2015-06-12

    Understanding the heterogeneity arising from the complex architecture of sedimentary sequences in alluvial fans is challenging. This study develops a statistical inverse framework in a multi-zone transition probability approach for characterizing the heterogeneity in alluvial fans. An analytical solution of the transition probability matrix is used to define the statistical relationships among different hydrofacies and their mean lengths, integral scales, and volumetric proportions. A statistical inversion is conducted to identify the multi-zone transition probability models and estimate the optimal statistical parameters using the modified Gauss–Newton–Levenberg–Marquardt method. The Jacobian matrix is computed by the sensitivity equation method, which results in anmore » accurate inverse solution with quantification of parameter uncertainty. We use the Chaobai River alluvial fan in the Beijing Plain, China, as an example for elucidating the methodology of alluvial fan characterization. The alluvial fan is divided into three sediment zones. In each zone, the explicit mathematical formulations of the transition probability models are constructed with optimized different integral scales and volumetric proportions. The hydrofacies distributions in the three zones are simulated sequentially by the multi-zone transition probability-based indicator simulations. Finally, the result of this study provides the heterogeneous structure of the alluvial fan for further study of flow and transport simulations.« less

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

    USGS Publications Warehouse

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

    1999-01-01

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

  12. AVO inversion based on inverse operator estimation in trust region

    NASA Astrophysics Data System (ADS)

    Yin, Xing-Yao; Deng, Wei; Zong, Zhao-Yun

    2016-04-01

    Amplitude variation with offset (AVO) inversion is widely utilized in exploration geophysics, especially for reservoir prediction and fluid identification. Inverse operator estimation in the trust region algorithm is applied for solving AVO inversion problems in which optimization and inversion directly are integrated. The L1 norm constraint is considered on the basis of reasonable initial model in order to improve effciency and stability during the AVO inversion process. In this study, high-order Zoeppritz approximation is utilized to establish the inversion objective function in which variation of {{v}\\text{p}}/{{v}\\text{s}} with time is taken into consideration. A model test indicates that the algorithm has a relatively higher stability and accuracy than the damp least-squares algorithm. Seismic data inversion is feasible and inversion values of three parameters ({{v}\\text{p}},{{v}\\text{s}},ρ ) maintain good consistency with logging curves.

  13. Kinematic hardening in creep of Zircaloy

    NASA Astrophysics Data System (ADS)

    Sedláček, Radan; Deuble, Dietmar

    2016-10-01

    Results of biaxial creep tests with stress changes on Zircaloy-2 tube samples are presented. A Hollomon-type viscoplastic strain hardening model is extended by the Armstrong-Frederic nonlinear kinematic hardening law, resulting in a mixed (i.e. isotropic and kinematic) strain hardening model. The creep tests with stress changes and similar tests published in the literature are simulated by the models. It is shown that introduction of the kinematic strain hardening in the viscoplastic strain hardening model is sufficient to describe the creep transients following stress drops, stress reversals and stress removals.

  14. Inverse heat conduction problems

    NASA Astrophysics Data System (ADS)

    Orlande, Helcio Rangel Barreto

    We present the solution of the following inverse problems: (1) Inverse Problem of Estimating Interface Conductance Between Periodically Contacting Surfaces; (2) Inverse Problem of Estimating Interface Conductance During Solidification via Conjugate Gradient Method; (3) Determination of the Reaction Function in a Reaction-Diffusion Parabolic Problem; and (4) Simultaneous Estimation of Thermal Diffusivity and Relaxation Time with Hyperbolic Heat Conduction Model. Also, we present the solution of a direct problem entitled: Transient Thermal Constriction Resistance in a Finite Heat Flux Tube. The Conjugate Gradient Method with Adjoint Equation was used in chapters 1-3. The more general function estimation approach was treated in these chapters. In chapter 1, we solve the inverse problem of estimating the timewise variation of the interface conductance between periodically contacting solids, under quasi-steady-state conditions. The present method is found to be more accurate than the B-Spline approach for situations involving small periods, which are the most difficult on which to perform the inverse analysis. In chapter 2, we estimate the timewise variation of the interface conductance between casting and mold during the solidification of aluminum. The experimental apparatus used in this study is described. In chapter 3, we present the estimation of the reaction function in a one dimensional parabolic problem. A comparison of the present function estimation approach with the parameter estimation technique, wing B-Splines to approximate the reaction function, revealed that the use of function estimation reduces the computer time requirements. In chapter 4 we present a finite difference solution for the transient constriction resistance in a cylinder of finite length with a circular contact surface. A numerical grid generation scheme was used to concentrate grid points in the regions of high temperature gradients in order to reduce discretization errors. In chapter 6, we

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

    NASA Technical Reports Server (NTRS)

    Bayo, Eduardo; Ledesma, Ragnar

    1993-01-01

    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.

  16. Carpal kinematics of lunotriquetral dissociations.

    PubMed

    Li, G; Rowen, B; Tokunaga, D; Ryu, J; Kato, H; Kihira, M

    1991-01-01

    The purpose of this study is to investigate the carpal kinematics after serial arthroscopic sectioning of the ligaments at the lunotriquetral joint, without damaging the capsule and other soft tissues of the wrist. Six cadaver wrists were studied and a custom designed three-dimensional mechanical digitizer was utilized. Three sets of digitization were performed for a normal state, after arthroscopic sectioning of lunotriquetral interosseous ligament (stage A), and after further sectioning of volar radiolunotriquetral ligament (stage B). Motion of the scaphoid, lunate, triquetrum, capitate and hamate was studied. The results indicated that the motion of the triquetrum was significantly increased at stage A, particularly after 15 degrees of ulnar deviation. An increased motion at the lunotriquetral joint was observed at stage B, which was mainly due to the significantly decreased lunate extension motion and the increased triquetrum extension motion during wrist extension. This study suggested that the lunotriquetral interosseous ligament plays the most important role for the stabilization of the lunotriquetral joint during wrist ulnar deviation, while the volar radiolunotriquetral ligament may function as a stabilizer for the lunotriquetral joint during wrist extension. PMID:2065165

  17. Milky Way halo gas kinematics

    NASA Technical Reports Server (NTRS)

    Danly, L.

    1986-01-01

    Measurements of high resolution, short wavelength absorption data taken by IUE toward high latitude O and B stars are presented in a discussion of the large scale kinematic properties of Milky Way Halo gas. An analysis of these data demonstrates that: (1) the obsrved absorption widths (FWHM) of Si II are very large, ranging up to 150 Km/s for the most distant halo star; this is much larger than is generally appreciated from optical data; (2) the absorption is observed to be systematically negative in radial velocity, indicating that cool material is, on the whole, flowing toward the disk of the galaxy; (3) there is some evidence for asymmetry between the northern and southern galactic hemispheres, in accordance with the HI 21 cm data toward the galactic poles; (4) low column density gas with highly negative radial LSR velocity (V less than -70 km/s) can be found toward stars beyond 1-3 kpc in the northern galactic hemisphere in all four quadrants of galactic longitude; and (5) only the profiles toward stars in the direction of known high velocity HI features show a clear two component structure.

  18. Edge-driven microplate kinematics

    USGS Publications Warehouse

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

    1993-01-01

    It is known from plate tectonic reconstructions that oceanic microplates undergo rapid rotation about a vertical axis and that the instantaneous rotation axes describing the microplate's motion relative to the bounding major plates are frequently located close to its margins with those plates, close to the tips of propagating rifts. We propose a class of edge-driven block models to illustrate how slip across the microplate margins, block rotation, and propagation of rifting may be related to the relative motion of the plates on either side. An important feature of these edge-driven models is that the instantaneous rotation axes are always located on the margins between block and two bounding plates. According to those models the pseudofaults or traces of disrupted seafloor resulting from the propagation of rifting between microplate and major plates may be used independently to approximately trace the continuous kinematic evolution of the microplate back in time. Pseudofault geometries and matching rotations of the Easter microplate show that for most of its 5 m.y. history, block rotation could be driven by the drag of the Nazca and Pacific plates on the microplate's edges rather than by a shear flow of mantle underneath.

  19. Kinematics of sport wheelchair propulsion.

    PubMed

    Coutts, K D

    1990-01-01

    Eight international caliber wheelchair male athletes (3 basketball, 5 distance track) performed an all-out propulsion effort from a standing start for 10 seconds on a wheelchair ergometer. Comparisons between the basketball and track athletes on linear wheelchair and push rim velocity during the first 3 pushes and the peak value indicated that the basketball players had a significantly (p less than .05) higher push rim velocity throughout the effort and a higher wheelchair velocity only at the end of the first push. The track athletes attained a significantly higher peak wheelchair velocity. Graphical comparison of the best individual basketball and track athletes' performances indicated that the track athletes caught up to the basketball players after about 3.7 seconds or 12 meters and travelled 49 meters in the 10 seconds, compared to 37 meters for the basketball players. Differences in push rim and wheel diameter are considered the major factor in the noted differences in propulsion kinematics of basketball and track wheelchairs.

  20. Inverse Functions and their Derivatives.

    ERIC Educational Resources Information Center

    Snapper, Ernst

    1990-01-01

    Presented is a method of interchanging the x-axis and y-axis for viewing the graph of the inverse function. Discussed are the inverse function and the usual proofs that are used for the function. (KR)

  1. Kinematic modeling of folding above listric propagating thrusts

    NASA Astrophysics Data System (ADS)

    Cardozo, Nestor; Brandenburg, J. P.

    2014-03-01

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

  2. Intersections, ideals, and inversion

    SciTech Connect

    Vasco, D.W.

    1998-10-01

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

  3. ModEM: A modular system for inversion of elecgtromagnetic geophysical data

    NASA Astrophysics Data System (ADS)

    Egbert, G. D.; Kelbert, A.; Meqbel, N.; Weng, A.

    2010-12-01

    We have developed a modular system of computer codes for inversion of electromagnetic (EM) geophysical data (ModEM). ModEM allows for rapid adaptation of inversion algorithms developed for one purpose (e.g., three-dimensional magnetotellurics (MT)) to other EM problems (e.g., controlled source EM). The modular approach can also simplify maintenance of the inversion code, as well as development of new capabilities -- e.g., allowing for new data types such as the inter-site transfer functions in MT, or modifying model regularization. Basic data objects (model parameters, solution vectors, data vectors) are treated as abstract data types, with a standard set of methods developed for each class, including creation and destruction, and, as appropriate, linear algebra or other vector space methods. Operators required for gradient computations are developed as mappings between these basic object classes. Only these abstract data objects and mappings are manipulated by higher level Jacobian and inversion routines, with no reference to the problem specific details required for a specific EM method, or for the numerical implementation of the forward solver. Required problem-specific components are instantiated at the lowest levels of the system, with details hidden from generic top-level routines by an interface layer. Parallelization using MPI has been implemented at the top level, and is thus applicable to any problem embedded in ModEM. To illustrate the flexibility of the system, we consider applications to two- and three-dimensional MT inversion, as well as simple controlled source EM problems.

  4. Non-equilibrium Kinematics in Merging Galaxies

    NASA Astrophysics Data System (ADS)

    Mihos, J. C.

    Measurements of the kinematics of merging galaxies are often used to derive dynamical masses, study evolution onto the fundamental plane, or probe relaxation processes. These measurements are often compromised to some degree by strong non-equilibrium motions in the merging galaxies. This talk focuses on the evolution of the kinematics of merging galaxies, and highlights some pitfalls which occur when studying non-equilibrium systems.

  5. Flight control in the hawkmoth Manduca sexta: the inverse problem of hovering.

    PubMed

    Hedrick, T L; Daniel, T L

    2006-08-01

    The inverse problem of hovering flight, that is, the range of wing movements appropriate for sustained flight at a fixed position and orientation, was examined by developing a simulation of the hawkmoth Manduca sexta. Inverse problems arise when one is seeking the parameters that are required to achieve a specified model outcome. In contrast, forward problems explore the outcomes given a specified set of input parameters. The simulation was coupled to a microgenetic algorithm that found specific sequences of wing and body motions, encoded by ten independent kinematic parameters, capable of generating the fixed body position and orientation characteristic of hovering flight. Additionally, we explored the consequences of restricting the number of free kinematic parameters and used this information to assess the importance to flight control of individual parameters and various combinations of them. Output from the simulated moth was compared to kinematic recordings of hovering flight in real hawkmoths; the real and simulated moths performed similarly with respect to their range of variation in position and orientation. The simulated moth also used average wingbeat kinematics (amplitude, stroke plane orientation, etc) similar to those of the real moths. However, many different subsets of the available kinematic were sufficient for hovering flight and available kinematic data from real moths does not include sufficient detail to assess which, if any, of these was consistent with the real moth. This general result, the multiplicity of possible hovering kinematics, shows that the means by which Manduca sexta actually maintains position and orientation may have considerable freedom and therefore may be influenced by many other factors beyond the physical and aerodynamic requirements of hovering flight.

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

    PubMed Central

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

    2012-01-01

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

  7. Application of Jacobian-free Newton–Krylov method in implicitly solving two-fluid six-equation two-phase flow problems: Implementation, validation and benchmark

    DOE PAGES

    Zou, Ling; Zhao, Haihua; Zhang, Hongbin

    2016-03-09

    This work represents a first-of-its-kind successful application to employ advanced numerical methods in solving realistic two-phase flow problems with two-fluid six-equation two-phase flow model. These advanced numerical methods include high-resolution spatial discretization scheme with staggered grids (high-order) fully implicit time integration schemes, and Jacobian-free Newton–Krylov (JFNK) method as the nonlinear solver. The computer code developed in this work has been extensively validated with existing experimental flow boiling data in vertical pipes and rod bundles, which cover wide ranges of experimental conditions, such as pressure, inlet mass flux, wall heat flux and exit void fraction. Additional code-to-code benchmark with the RELAP5-3Dmore » code further verifies the correct code implementation. The combined methods employed in this work exhibit strong robustness in solving two-phase flow problems even when phase appearance (boiling) and realistic discrete flow regimes are considered. Transitional flow regimes used in existing system analysis codes, normally introduced to overcome numerical difficulty, were completely removed in this work. As a result, this in turn provides the possibility to utilize more sophisticated flow regime maps in the future to further improve simulation accuracy.« less

  8. Applications of high-resolution spatial discretization scheme and Jacobian-free Newton–Krylov method in two-phase flow problems

    SciTech Connect

    Zou, Ling; Zhao, Haihua; Zhang, Hongbin

    2015-09-01

    The majority of the existing reactor system analysis codes were developed using low-order numerical schemes in both space and time. In many nuclear thermal–hydraulics applications, it is desirable to use higher-order numerical schemes to reduce numerical errors. High-resolution spatial discretization schemes provide high order spatial accuracy in smooth regions and capture sharp spatial discontinuity without nonphysical spatial oscillations. In this work, we adapted an existing high-resolution spatial discretization scheme on staggered grids in two-phase flow applications. Fully implicit time integration schemes were also implemented to reduce numerical errors from operator-splitting types of time integration schemes. The resulting nonlinear system has been successfully solved using the Jacobian-free Newton–Krylov (JFNK) method. The high-resolution spatial discretization and high-order fully implicit time integration numerical schemes were tested and numerically verified for several two-phase test problems, including a two-phase advection problem, a two-phase advection with phase appearance/disappearance problem, and the water faucet problem. Numerical results clearly demonstrated the advantages of using such high-resolution spatial and high-order temporal numerical schemes to significantly reduce numerical diffusion and therefore improve accuracy. Our study also demonstrated that the JFNK method is stable and robust in solving two-phase flow problems, even when phase appearance/disappearance exists.

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

    SciTech Connect

    Salinger, Andy; Evans, Katherine J; Lemieux, Jean-Francois; Holland, David; Payne, Tony; Price, Stephen; Knoll, Dana

    2011-01-01

    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.

  10. A new div-curl result. Applications to the homogenization of elliptic systems and to the weak continuity of the Jacobian

    NASA Astrophysics Data System (ADS)

    Briane, M.; Casado Díaz, J.

    2016-04-01

    In this paper a new div-curl result is established in an open set Ω of RN, N ≥ 2, for the product σn ṡηn of two sequences of vector-valued functions σn, ηn such that σn is bounded in Lp(Ω) N, ηn is bounded in Lq(Ω) N, with 1 / p + 1 / q = 1 + 1 / (N - 1), and such that divσn, curlηn are compact in suitable spaces. The new assumption is that the product converges weakly in W - 1 , 1 (Ω). The approach is also new in the topic, and is based on a compactness result for bounded sequences in W 1 , q (Ω) through a suitable selection of annuli on which the gradients are not too high, in the spirit of [26,32] and using the imbedding of W 1 , q into Lp‧ for the unit sphere of RN. The div-curl result is applied to the homogenization of equi-coercive systems whose coefficients are equi-bounded in Lρ (Ω) for some ρ >N - 1/2 if N > 2, or in L1 (Ω) if N = 2. It also allows us to prove a weak continuity result for the Jacobian for bounded sequences in W 1 , N - 1 (Ω) satisfying an alternative assumption to the L∞-strong estimate of [8]. Two examples show the sharpness of the results.

  11. a Six-Link Kinematic Chain Model of Human Body Using Kane's Method

    NASA Astrophysics Data System (ADS)

    Rambely, A. S.; Fazrolrozi

    A biomechanics model of six-link kinematic chain of human body is developed by using Kane's method. The kinematic data comprise of six segments; foot, calf, thigh, trunk, upper arm and forearm, are obtained through data collection of walking, running and jumping using the Vicon Nexus system. The motion capture system uses 12 Vicon MX-3+ cameras and 12 Vicon MX-F40 cameras, two DV (50 Hz) cameras and a force plate (100 Hz). Inverse dynamics approach is used to obtain the unknown value of torques produced by joint segments during walking, running and jumping activities. The results show that the largest value of torques produced occurs at the foot segment.

  12. Kinematic numerators and a double-copy formula for N=4 super-Yang-Mills residues

    NASA Astrophysics Data System (ADS)

    Litsey, Sean; Stankowicz, James

    2014-07-01

    Recent work by Cachazo et al.arXiv:1309.0885 shows that connected prescription residues obey the global identities of N=4 super-Yang-Mills amplitudes. In particular, they obey the Bern-Carrasco-Johansson (BCJ) amplitude identities. Here we offer a new way of interpreting this result via objects that we call residue numerators. These objects behave like the kinematic numerators introduced by BCJ except that they are associated with individual residues. In particular, these new objects satisfy a double-copy formula relating them to the residues appearing in recently discovered analogs of the connected prescription integrals for N=8 supergravity. Along the way, we show that the BCJ amplitude identities are equivalent to the consistency condition that allows kinematic numerators to be expressed as amplitudes using a generalized inverse.

  13. [Kinematics Modeling and Analysis of Central-driven Robot for Upper Limb Rehabilitation after Stroke].

    PubMed

    Yi, Jinhua; Yu, Hongliu; Zhang, Ying; Hu, Xin; Shi, Ping

    2015-12-01

    The present paper proposed a central-driven structure of upper limb rehabilitation robot in order to reduce the volume of the robotic arm in the structure, and also to reduce the influence of motor noise, radiation and other adverse factors on upper limb dysfunction patient. The forward and inverse kinematics equations have been obtained with using the Denavit-Hartenberg (D-H) parameter method. The motion simulation has been done to obtain the angle-time curve of each joint and the position-time curve of handle under setting rehabilitation path by using Solid Works software. Experimental results showed that the rationality with the central-driven structure design had been verified by the fact that the handle could move under setting rehabilitation path. The effectiveness of kinematics equations had been proved, and the error was less than 3° by comparing the angle-time curves obtained from calculation with those from motion simulation. PMID:27079086

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

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  15. Interplanetary stream magnetism - Kinematic effects

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Barouch, E.

    1976-01-01

    The particle density and the magnetic-field intensity and direction are calculated for volume elements of the solar wind as a function of the initial magnetic-field direction and the initial speed gradient. It is assumed that the velocity is constant and radial. These assumptions are approximately valid between about 0.1 and 1.0 AU for many streams. Time profiles of the particle density, field intensity, and velocity are calculated for corotating streams, neglecting effects of pressure gradients. The compression and rarefaction of the magnetic field depend sensitively on the initial field direction. By averaging over a typical stream, it is found that the average radial field intensity is inversely proportional to the square of the heliocentric distance, whereas the average intensity in the direction of the planets' motion does not vary in a simple way, consistent with deep space observations. Changes of field direction may be very large, depending on the initial angle; but when the initial angle at 0.1 AU is such that the base of the field line corotates with the sun, the spiral angle is the preferred direction at 1 AU. The theory is also applicable to nonstationary flows.

  16. KINEMATIC AND SPATIAL SUBSTRUCTURE IN NGC 2264

    SciTech Connect

    Tobin, John J.; Hartmann, Lee; Hsu, Wen-Hsin; Mateo, Mario; Fűrész, Gabor

    2015-04-15

    We present an expanded kinematic study of the young cluster NGC 2264 based upon optical radial velocities measured using multi-fiber echelle spectroscopy at the 6.5 m MMT and Magellan telescopes. We report radial velocities for 695 stars, of which approximately 407 stars are confirmed or very likely members. Our results more than double the number of members with radial velocities from Fűrész et al., resulting in a much better defined kinematic relationship between the stellar population and the associated molecular gas. In particular, we find that there is a significant subset of stars that are systematically blueshifted with respect to the molecular ({sup 13}CO) gas. The detection of Lithium absorption and/or infrared excesses in this blueshifted population suggests that at least some of these stars are cluster members; we suggest some speculative scenarios to explain their kinematics. Our results also more clearly define the redshifted population of stars in the northern end of the cluster; we suggest that the stellar and gas kinematics of this region are the result of a bubble driven by the wind from O7 star S Mon. Our results emphasize the complexity of the spatial and kinematic structure of NGC 2264, important for eventually building up a comprehensive picture of cluster formation.

  17. Kinematic reconstruction of the Caribbean region since the Early Jurassic

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  18. Analysis of the kinematic characteristics of a high-speed parallel robot with Schönflies motion: Mobility, kinematics, and singularity

    NASA Astrophysics Data System (ADS)

    Xie, Fugui; Liu, Xin-Jun

    2016-06-01

    This study introduces a high-speed parallel robot with Schönflies motion. This robot exhibits a promising prospect in realizing high-speed pick-andplace manipulation for packaging production lines. The robot has four identical limbs and a single platform. Its compact structure and single-platform concept provides this robot with good dynamic response potential. A line graph method based on Grassmann line geometry is used to investigate the mobility characteristics of the proposed robot. A generalized Blanding rule is also introduced into this procedure to realize mutual conversion between the line graphs for motions and constraints. Subsequently, the inverse kinematics is derived, and the singularity issue of the robot is investigated using both qualitative and quantitative approaches. Input and output transmission singularity indices are defined based on the reciprocal product in screw theory and the virtual coefficient by considering motion/force transmission performance. Thereafter, the singular loci of the proposed robot with specific geometric parameters are derived. The mobility analysis, inverse kinematics modeling, and singularity analysis conducted in this study are helpful in developing the robot.

  19. Inverse Kinematics Studies of Intermediate-Energy Reactions Relevant for SEE and Medical Problems

    NASA Astrophysics Data System (ADS)

    Aichelin, J.; Bargholtz, Ch.; Blomgren, J.; Budzanowski, A.; Chubarov, M.; Czech, B.; Ekström, C.; Gerén, L.; Jakobsson, B.; Kolozhvari, A.; Lozhkin, O.; Murin, Yu.; Nomokonov, P.; Olsson, N.; Persson, H.; Pljuschev, V.; Skwirczynska, I.; Tang, H. H. K.; Tegnér, P.-E.; Westerberg, L.; Zartova, I.; Zubkov, M.; Watanabe, Y.

    2005-05-01

    The lack of systematic experimental checks on the intermediate-energy nuclear model simulations of heavily ionizing recoils from nucleon-nucleus collisions — critical inputs for the Single Event Effect analysis of microelectronics and dosimetry calculations including high-LET components in the cancer tumor radiation therapy — has been a primary motivation for a new experiment planned at the CELSIUS nuclear storage ring of The Svedberg Laboratory, Uppsala, Sweden. Details of the experiment and the first results from a feasibility study are presented here.

  20. Recent Inversion, Seismic Potential, and Neogene Kinematics of the Algerian Margin (Western Mediterranean) from Offshore Studies

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    NASA Astrophysics Data System (ADS)

    McCaffrey, R.

    2003-12-01

    The active deformation of the southwestern US (30° to 41° N) is represented by a finite number of rotating, elastic spherical caps. Horizontal GPS velocities (1583), fault slip rates (94), and earthquake slip vectors (116) are inverted for block angular velocities, locking on block-bounding faults, and the rotation of individual GPS velocity fields relative to North America. GPS velocities are modeled as a combination of rigid block rotations and elastic strain rates resulting from interactions of adjacent blocks across bounding faults. The resulting Pacific - North America pole is indistinguishable from that of Beavan et al. (2001) and satisfies spreading in the Gulf of California and earthquake slip vectors in addition to GPS. The largest blocks, the Sierra Nevada - Great Valley and the eastern Basin and Range, show internal strain rates, after removing the elastic component, of only a few nanostrain/a, demonstrating long term approximately rigid behavior. Most fault slip data are satisfied except that the San Jacinto fault appears to be significantly faster than inferred from geology while the Coachella and San Bernardino segments of the San Andreas fault are slower, suggesting the San Andreas system is straightening out in Southern California. Vertical axis rotation rates for most blocks are clockwise and in magnitude more like the Pacific than North America. One exception is the eastern Basin and Range (242° E to 248° E) which rotates slowly anticlockwise about a pole offshore Baja.

  2. SMACK - SMOOTHING FOR AIRCRAFT KINEMATICS

    NASA Technical Reports Server (NTRS)

    Bach, R.

    1994-01-01

    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

  3. Optimal pumping kinematics of a cilium

    NASA Astrophysics Data System (ADS)

    Eloy, Christophe; Lauga, Eric

    2012-11-01

    In a variety of biological processes, eukaryotic cells use cilia to transport flow. Although the internal molecular structure of cilia has been remarkably conserved throughout evolution, experimental observations report qualitatively diverse kinematics in different species. To address this diversity, we have determined numerically the kinematics of the most efficient cilium. Specifically, we have computed the time-periodic deformation of a wall-bound elastic filament leading to transport of a surrounding fluid at minimum energetic cost. Here, the energetic cost is taken to be the sum of positive works done by the internal torques, such that elastic energy is not conservative. The optimal kinematics are found to strongly depend on the cilium bending rigidity through a single dimensionless number, the Sperm number Sp, and closely resemble the two-stroke ciliary beating pattern observed experimentally. We acknowledge supports from the EU (fellowship PIOF-GA-2009-252542 to C.E.) and the NSF (grant CBET-0746285 to E.L.).

  4. Numerical algebraic geometry and algebraic kinematics

    NASA Astrophysics Data System (ADS)

    Wampler, Charles W.; Sommese, Andrew J.

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

  5. Computer Assisted Mechanical Axis and Kinematic TKA

    PubMed Central

    McEwen, Peter; Mahoharan, Varaguna

    2016-01-01

    Introduction: Total knee arthroplasty (TKA) has traditionally been and largely continues to be aligned mechanically, that being with a neutral coronal plane mechanical tibiofemoral axis and a joint line orientated at 900 to this axis. Femoral component rotation is set by gap balancing or by externally rotating 30 from any of a number femoral reference lines. This produces a rectangular flexion gap and relaxes patellar tracking. Kinematic alignment (KA) is an alternative technique that aims to restore premorbid alignment, joint orientation and ligament tension. The basic premise for this technique is based on evidence that the medial and lateral femoral condyles consistently equate to cylinders of equal or near equal size and that therefore with a fixed radius, cruciate retaining implant, matched distal femoral, posterior femoral and proximal tibial resections, accounting for bone and cartilage already lost will reproduce the premorbid joint line and restore native premorbid kinematics. Femoral rotation is therefore referenced off the prearthritic posterior condylar axis (PCA) that is on average internally rotated to the AP axis. Kinematic alignment therefore has the potential to challenge patellar tracking, increase patellar load and potentially increase patellar complications. Method: Case control study – level of evidence III-2. Between November 2012 and June 2013 the senior author completed 104 consecutive computer assisted (CAS) kinematically aligned total knee arthroplasties (TKA) with a cruciate retaining, fixed bearing, single radius implant. The results of these surgeries were compared with the results of 91 consecutive CAS mechanically aligned TKA done between November 2011 and October 2012 using the same navigation system and implant Implant sizing and positioning as well as gap measurement and ligament balance was done with computer assistance in all cases. Data was collected prospectively and analysed retrospectively. Results: The Oxford Knee Score

  6. Highly damped kinematic coupling for precision instruments

    DOEpatents

    Hale, Layton C.; Jensen, Steven A.

    2001-01-01

    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.

  7. Kinematics of the Most Efficient Cilium

    NASA Astrophysics Data System (ADS)

    Eloy, Christophe; Lauga, Eric

    2012-07-01

    In a variety of biological processes, eukaryotic cells use cilia to transport flow. Although cilia have a remarkably conserved internal molecular structure, experimental observations report very diverse kinematics. To address this diversity, we determine numerically the kinematics and energetics of the most efficient cilium. Specifically, we compute the time-periodic deformation of a wall-bound elastic filament leading to transport of a surrounding fluid at minimum energetic cost, where the cost is taken to be the positive work done by all internal molecular motors. The optimal kinematics are found to strongly depend on the cilium bending rigidity through a single dimensionless number, the Sperm number, and closely resemble the two-stroke ciliary beating pattern observed experimentally.

  8. Dark energy as a kinematic effect

    NASA Astrophysics Data System (ADS)

    Jennen, H.; Pereira, J. G.

    2016-03-01

    We present a generalization of teleparallel gravity that is consistent with local spacetime kinematics regulated by the de Sitter group SO(1 , 4) . The mathematical structure of teleparallel gravity is shown to be given by a nonlinear Riemann-Cartan geometry without curvature, which inspires us to build the generalization on top of a de Sitter-Cartan geometry with a cosmological function. The cosmological function is given its own dynamics and naturally emerges nonminimally coupled to the gravitational field in a manner akin to teleparallel dark energy models or scalar-tensor theories in general relativity. New in the theory here presented, the cosmological function gives rise to a kinematic contribution in the deviation equation for the world lines of adjacent free-falling particles. While having its own dynamics, dark energy manifests itself in the local kinematics of spacetime.

  9. Temporal and kinematic consistency predict sequence awareness.

    PubMed

    Jaynes, Molly J; Schieber, Marc H; Mink, Jonathan W

    2016-10-01

    Many human motor skills can be represented as a hierarchical series of movement patterns. Awareness of underlying patterns can improve performance and decrease cognitive load. Subjects (n = 30) tapped a finger sequence with changing stimulus-to-response mapping and a common movement sequence. Thirteen subjects (43 %) became aware that they were tapping a familiar movement sequence during the experiment. Subjects who became aware of the underlying motor pattern tapped with greater kinematic and temporal consistency from task onset, but consistency was not sufficient for awareness. We found no effect of age, musical experience, tapping evenness, or inter-key-interval on awareness of the pattern in the motor response. We propose that temporal or kinematic consistency reinforces a pattern representation, but cognitive engagement with the contents of the sequence is necessary to bring the pattern to conscious awareness. These findings predict benefit for movement strategies that limit temporal and kinematic variability during motor learning. PMID:27324192

  10. Stress inversion assumptions review

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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

  11. Inverse magnetorheological fluids.

    PubMed

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

    2014-09-01

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

  12. Graph Theory Roots of Spatial Operators for Kinematics and Dynamics

    NASA Technical Reports Server (NTRS)

    Jain, Abhinandan

    2011-01-01

    Spatial operators have been used to analyze the dynamics of robotic multibody systems and to develop novel computational dynamics algorithms. Mass matrix factorization, inversion, diagonalization, and linearization are among several new insights obtained using such operators. While initially developed for serial rigid body manipulators, the spatial operators and the related mathematical analysis have been shown to extend very broadly including to tree and closed topology systems, to systems with flexible joints, links, etc. This work uses concepts from graph theory to explore the mathematical foundations of spatial operators. The goal is to study and characterize the properties of the spatial operators at an abstract level so that they can be applied to a broader range of dynamics problems. The rich mathematical properties of the kinematics and dynamics of robotic multibody systems has been an area of strong research interest for several decades. These properties are important to understand the inherent physical behavior of systems, for stability and control analysis, for the development of computational algorithms, and for model development of faithful models. Recurring patterns in spatial operators leads one to ask the more abstract question about the properties and characteristics of spatial operators that make them so broadly applicable. The idea is to step back from the specific application systems, and understand more deeply the generic requirements and properties of spatial operators, so that the insights and techniques are readily available across different kinematics and dynamics problems. In this work, techniques from graph theory were used to explore the abstract basis for the spatial operators. The close relationship between the mathematical properties of adjacency matrices for graphs and those of spatial operators and their kernels were established. The connections hold across very basic requirements on the system topology, the nature of the component

  13. Kinetic and kinematic differences between deadlifts and goodmornings

    PubMed Central

    2013-01-01

    Background In order to improve training performance, as well as avoid overloading during prevention and rehabilitation exercises in patients, the aim of this study was to understand the biomechanical differences in the knee, hip and the back between the exercises “Goodmornings” (GMs) and “Deadlifts” (DLs). Methods The kinetics and kinematics of 13 subjects, performing GMs and DLs with an additional 25% (GMs), 25% and 50% (DLs) body weight (BW) on the barbell were analysed. Using the kinetic and kinematic data captured using a 3D motion analysis and force plates, an inverse approach with a quasi-static solution was used to calculate the sagittal moments and angles in the knee, hip and the trunk. The maximum moments and joint angles were statistically tested using ANOVA with a Bonferroni adjustment. Results The observed maximal flexion angle of the knee was 5.3 ± 6.7° for GMs and 107.8 ± 22.4° and 103.4 ± 22.6° for DLs with 25% and 50% BW respectively. Of the hip, the maximal flexion angle was 25% smaller during GMs compared to DLs. No difference in kinematics of the trunk between the two exercises was observed. For DLs, the resulting sagittal moment in the knee was an external flexion moment, whereas during GMs an external extension moment was present. Importantly, no larger sagittal knee joint moments were observed when using a heavier weight on the barbell during DLs, but higher sagittal moments were found at the hip and L4/L5. Compared to GMs, DLs produced a lower sagittal moment at the hip using 25% BW while generating the same sagittal moment at L4/L5. Conclusions The two exercises exhibited different motion patterns for the lower extremities but not for the trunk. To strengthen the hip while including a large range of motion, DLs using 50% BW should be chosen. Due to their ability to avoid knee flexion or a knee flexion moment, GMs should be preferentially chosen over DLs as ACL rupture prevention exercises. Here, in order to shift

  14. Kinematics and Control of Robot Manipulators

    NASA Astrophysics Data System (ADS)

    Paden, Bradley Evan

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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

  16. Wavelet Sparse Approximate Inverse Preconditioners

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

    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.

  17. Inverse problem for Bremsstrahlung radiation

    SciTech Connect

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

    1991-10-01

    For certain predominantly one-dimensional distribution functions, an analytic inversion has been found which yields the velocity distribution of superthermal electrons given their Bremsstrahlung radiation. 5 refs.

  18. Gait Kinematic Analysis in Water Using Wearable Inertial Magnetic Sensors.

    PubMed

    Fantozzi, Silvia; Giovanardi, Andrea; Borra, Davide; Gatta, Giorgio

    2015-01-01

    Walking is one of the fundamental motor tasks executed during aquatic therapy. Previous kinematics analyses conducted using waterproofed video cameras were limited to the sagittal plane and to only one or two consecutive steps. Furthermore, the set-up and post-processing are time-consuming and thus do not allow a prompt assessment of the correct execution of the movements during the aquatic session therapy. The aim of the present study was to estimate the 3D joint kinematics of the lower limbs and thorax-pelvis joints in sagittal and frontal planes during underwater walking using wearable inertial and magnetic sensors. Eleven healthy adults were measured during walking both in shallow water and in dry-land conditions. Eight wearable inertial and magnetic sensors were inserted in waterproofed boxes and fixed to the body segments by means of elastic modular bands. A validated protocol (Outwalk) was used. Gait cycles were automatically segmented and selected if relevant intraclass correlation coefficients values were higher than 0.75. A total of 704 gait cycles for the lower limb joints were normalized in time and averaged to obtain the mean cycle of each joint, among participants. The mean speed in water was 40% lower than that of the dry-land condition. Longer stride duration and shorter stride distance were found in the underwater walking. In the sagittal plane, the knee was more flexed (≈ 23°) and the ankle more dorsiflexed (≈ 9°) at heel strike, and the hip was more flexed at toe-off (≈ 13°) in water than on land. On the frontal plane in the underwater walking, smoother joint angle patterns were observed for thorax-pelvis and hip, and ankle was more inversed at toe-off (≈ 7°) and showed a more inversed mean value (≈ 7°). The results were mainly explained by the effect of the speed in the water as supported by the linear mixed models analysis performed. Thus, it seemed that the combination of speed and environment triggered modifications in the

  19. Gait Kinematic Analysis in Water Using Wearable Inertial Magnetic Sensors

    PubMed Central

    Fantozzi, Silvia; Giovanardi, Andrea; Borra, Davide; Gatta, Giorgio

    2015-01-01

    Walking is one of the fundamental motor tasks executed during aquatic therapy. Previous kinematics analyses conducted using waterproofed video cameras were limited to the sagittal plane and to only one or two consecutive steps. Furthermore, the set-up and post-processing are time-consuming and thus do not allow a prompt assessment of the correct execution of the movements during the aquatic session therapy. The aim of the present study was to estimate the 3D joint kinematics of the lower limbs and thorax-pelvis joints in sagittal and frontal planes during underwater walking using wearable inertial and magnetic sensors. Eleven healthy adults were measured during walking both in shallow water and in dry-land conditions. Eight wearable inertial and magnetic sensors were inserted in waterproofed boxes and fixed to the body segments by means of elastic modular bands. A validated protocol (Outwalk) was used. Gait cycles were automatically segmented and selected if relevant intraclass correlation coefficients values were higher than 0.75. A total of 704 gait cycles for the lower limb joints were normalized in time and averaged to obtain the mean cycle of each joint, among participants. The mean speed in water was 40% lower than that of the dry-land condition. Longer stride duration and shorter stride distance were found in the underwater walking. In the sagittal plane, the knee was more flexed (≈ 23°) and the ankle more dorsiflexed (≈ 9°) at heel strike, and the hip was more flexed at toe-off (≈ 13°) in water than on land. On the frontal plane in the underwater walking, smoother joint angle patterns were observed for thorax-pelvis and hip, and ankle was more inversed at toe-off (≈ 7°) and showed a more inversed mean value (≈ 7°). The results were mainly explained by the effect of the speed in the water as supported by the linear mixed models analysis performed. Thus, it seemed that the combination of speed and environment triggered modifications in the

  20. Gait Kinematic Analysis in Water Using Wearable Inertial Magnetic Sensors.

    PubMed

    Fantozzi, Silvia; Giovanardi, Andrea; Borra, Davide; Gatta, Giorgio

    2015-01-01

    Walking is one of the fundamental motor tasks executed during aquatic therapy. Previous kinematics analyses conducted using waterproofed video cameras were limited to the sagittal plane and to only one or two consecutive steps. Furthermore, the set-up and post-processing are time-consuming and thus do not allow a prompt assessment of the correct execution of the movements during the aquatic session therapy. The aim of the present study was to estimate the 3D joint kinematics of the lower limbs and thorax-pelvis joints in sagittal and frontal planes during underwater walking using wearable inertial and magnetic sensors. Eleven healthy adults were measured during walking both in shallow water and in dry-land conditions. Eight wearable inertial and magnetic sensors were inserted in waterproofed boxes and fixed to the body segments by means of elastic modular bands. A validated protocol (Outwalk) was used. Gait cycles were automatically segmented and selected if relevant intraclass correlation coefficients values were higher than 0.75. A total of 704 gait cycles for the lower limb joints were normalized in time and averaged to obtain the mean cycle of each joint, among participants. The mean speed in water was 40% lower than that of the dry-land condition. Longer stride duration and shorter stride distance were found in the underwater walking. In the sagittal plane, the knee was more flexed (≈ 23°) and the ankle more dorsiflexed (≈ 9°) at heel strike, and the hip was more flexed at toe-off (≈ 13°) in water than on land. On the frontal plane in the underwater walking, smoother joint angle patterns were observed for thorax-pelvis and hip, and ankle was more inversed at toe-off (≈ 7°) and showed a more inversed mean value (≈ 7°). The results were mainly explained by the effect of the speed in the water as supported by the linear mixed models analysis performed. Thus, it seemed that the combination of speed and environment triggered modifications in the

  1. Kinematic Distances of Galactic Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Yang, A. Y.; Tian, W. W.; Zhu, H.; Leahy, D. A.; Wu, D.

    2016-03-01

    We construct H i absorption spectra for 18 planetary nebulae (PNs) and their background sources using data from the International Galactic Plane Survey. We estimate the kinematic distances of these PNs, among which 15 objects’ kinematic distances are obtained for the first time. The distance uncertainties of 13 PNs range from 10% to 50%, which is a significant improvement with uncertainties of a factor of two or three smaller than most previous distance measurements. We confirm that PN G030.2-00.1 is not a PN because of its large distance found here.

  2. Off-shell kinematics in nuclear processes

    NASA Astrophysics Data System (ADS)

    Thakur, Jagannath

    1983-11-01

    A semirelativistic model based on an approximate solution of the Bethe-Salpeter equation used previously to construct a conserved electromagnetic current with arbitrary interaction is generalized to arbitrary processes and extended to many body targets. Although the technique appears valid and useful for introducing kinematic corrections in processes off few body targets, a paradoxical result emerges for large nuclei in that the relevant form factors, which must be evaluated far off-shell, can be dramatically different from that for free nucleons, contrary to the usual picture of the nucleus as composed of nearly free nucleons. NUCLEAR REACTIONS Bethe-Salpeter equation, off-shell kinematics, impulse approximation, paradox for large nuclei.

  3. A kinematic model of Kármán gaiting in rainbow trout

    PubMed Central

    Akanyeti, Otar; Liao, James C.

    2013-01-01

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

  4. Calibration of parallel kinematic devices using sequential determination of kinematic parameters

    SciTech Connect

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

    2000-04-06

    In PKM Machines, the Cartesian position and orientation of the tool point carried on the platform is obtained from a kinematic model of the particular machine. Accurate positioning of these machines relies on the accurate knowledge of the parameters of the kinematic model unique to the particular machine. The parameters in the kinematic model include the spatial locations of the joint centers on the machine base and moving platform, the initial strut lengths, and the strut displacements. The strut displacements are readily obtained from sensors on the machine. However, the remaining kinematic parameters (joint center locations, and initial strut lengths) are difficult to determine when these machines are in their fully assembled state. The size and complexity of these machines generally makes it difficult and somewhat undesirable to determine the remaining kinematic parameters by direct inspection such as in a coordinate measuring machine. In order for PKMs to be useful for precision positioning applications, techniques must be developed to quickly calibrate the machine by determining the kinematic parameters without disassembly of the machine. A number of authors have reported techniques for calibration of PKMs (Soons, Masory, Zhuang et. al., Ropponen). In two other papers, the authors have reported on work recently completed by the University of Florida and Sandia National Laboratories on calibration of PKMs, which describes a new technique to sequentially determine the kinematic parameters of an assembled parallel kinematic device. The technique described is intended to be used with a spatial coordinate measuring device such as a portable articulated CMM measuring arm (Romer, Faro, etc.), a Laser Ball Bar (LBB), or a laser tracker (SMX< API, etc.). The material to be presented is as follows: (1) methods to identify the kinematic parameters of 6--6 variant Stewart platform manipulators including joint center locations relative to the workable and spindle nose

  5. Parallel computation of geometry control in adaptive truss structures

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    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.

  6. Modular theory of inverse systems

    NASA Technical Reports Server (NTRS)

    1979-01-01

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

  7. Inversion exercises inspired by mechanics

    NASA Astrophysics Data System (ADS)

    Groetsch, C. W.

    2016-02-01

    An elementary calculus transform, inspired by the centroid and gyration radius, is introduced as a prelude to the study of more advanced transforms. Analysis of the transform, including its inversion, makes use of several key concepts from basic calculus and exercises in the application and inversion of the transform provide practice in the use of technology in calculus.

  8. ANALYTIC MODELING OF THE MORETON WAVE KINEMATICS

    SciTech Connect

    Temmer, M.; Veronig, A. M.

    2009-09-10

    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.

  9. Stellar Archeology : Chemical Compositions and Kinematics

    NASA Astrophysics Data System (ADS)

    Stringer, Bayard; Carney, Bruce

    2011-10-01

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

  10. KINEMATICS OF STELLAR POPULATIONS IN POSTSTARBURST GALAXIES

    SciTech Connect

    Hiner, Kyle D.; Canalizo, Gabriela E-mail: khiner@astro-udec.cl

    2015-01-20

    Poststarburst galaxies host a population of early-type stars (A or F) but simultaneously lack indicators of ongoing star formation such as [O II] emission. Two distinct stellar populations have been identified in these systems: a young poststarburst population superimposed on an older host population. We present a study of nine poststarburst galaxies with the following objectives: (1) to investigate whether and how kinematical differences between the young and old populations of stars can be measured, and (2) to gain insight into the formation mechanism of the young population in these systems. We fit high signal-to-noise spectra with two independent populations in distinct spectral regions: the Balmer region, the Mg IB region, and the Ca triplet when available. We show that the kinematics of the two populations largely track one another if measured in the Balmer region with high signal-to-noise data. Results from examining the Faber-Jackson relation and the fundamental plane indicate that these objects are not kinematically disturbed relative to more evolved spheroids. A case study of the internal kinematics of one object in our sample shows it to be pressure supported and not rotationally dominated. Overall our results are consistent with merger-induced starburst scenarios where the young population is observed during the later stages of the merger.

  11. Kinematics of foldable discrete space cranes

    NASA Technical Reports Server (NTRS)

    Nayfeh, A. H.

    1985-01-01

    Exact kinematic description of a NASA proposed prototype foldable-deployable discrete space crane are presented. A computer program is developed which maps the geometry of the crane once controlling parameters are specified. The program uses a building block type approach in which it calculates the local coordinates of each repeating cell and then combines them with respect to a global coordinates system.

  12. Constrained tri-sphere kinematic positioning system

    DOEpatents

    Viola, Robert J

    2010-12-14

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

  13. Compton Effect with Non-Relativistic Kinematics

    ERIC Educational Resources Information Center

    Shivalingaswamy, T.; Kagali, B. A.

    2011-01-01

    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…

  14. Action Experience Changes Attention to Kinematic Cues

    PubMed Central

    Filippi, Courtney A.; Woodward, Amanda L.

    2016-01-01

    The current study used remote corneal reflection eye-tracking to examine the relationship between motor experience and action anticipation in 13-months-old infants. To measure online anticipation of actions infants watched videos where the actor’s hand provided kinematic information (in its orientation) about the type of object that the actor was going to reach for. The actor’s hand orientation either matched the orientation of a rod (congruent cue) or did not match the orientation of the rod (incongruent cue). To examine relations between motor experience and action anticipation, we used a 2 (reach first vs. observe first) × 2 (congruent kinematic cue vs. incongruent kinematic cue) between-subjects design. We show that 13-months-old infants in the observe first condition spontaneously generate rapid online visual predictions to congruent hand orientation cues and do not visually anticipate when presented incongruent cues. We further demonstrate that the speed that these infants generate predictions to congruent motor cues is correlated with their own ability to pre-shape their hands. Finally, we demonstrate that following reaching experience, infants generate rapid predictions to both congruent and incongruent hand shape cues—suggesting that short-term experience changes attention to kinematics. PMID:26913012

  15. Kinematic comparisons of 1996 Olympic baseball pitchers.

    PubMed

    Escamilla, R F; Fleisig, G S; Zheng, N; Barrentine, S W; Andrews, J R

    2001-09-01

    The aim of this study was to compare and evaluate the kinematics of baseball pitchers who participated in the 1996 XXVI Centennial Olympic Games. Two synchronized video cameras operating at 120 Hz were used to video 48 pitchers from Australia, Japan, the Netherlands, Cuba, Italy, Korea, Nicaragua and the USA. All pitchers were analysed while throwing the fastball pitch. Twenty-one kinematic parameters were measured at lead foot contact, during the arm cocking and arm acceleration phases, and at the instant of ball release. These parameters included stride length, foot angle and foot placement; shoulder abduction, shoulder horizontal adduction and shoulder external rotation; knee and elbow flexion; upper torso, shoulder internal rotation and elbow extension angular velocities; forward and lateral trunk tilt; and ball speed. A one-way analysis of variance (P < 0.01) was used to assess kinematic differences. Shoulder horizontal adduction and shoulder external rotation at lead foot contact and ball speed at the instant of ball release were significantly different among countries. The greater shoulder horizontal abduction observed in Cuban pitchers at lead foot contact is thought to be an important factor in the generation of force throughout the arm cocking and arm acceleration phases, and may in part explain why Cuban pitchers generated the greatest ball release speed. We conclude that pitching kinematics are similar among baseball pitchers from different countries.

  16. Kinematic Measurements from YouTube Videos

    ERIC Educational Resources Information Center

    Ruiz, Michael J.

    2009-01-01

    Video analysis of motion has been in use now for some time. However, some teachers may not have video equipment or may be looking for innovative ways to engage students with interesting applications at no cost. The recent advent of YouTube offers opportunities for students to measure kinematic properties of real-life events using their computers.…

  17. Kinematics of luminous blue compact galaxies

    NASA Astrophysics Data System (ADS)

    Östlin, Göran; Amram, Philippe; Boulesteix, Jaques; Bergvall, Nils; Masegosa, Josefa; Márquez, Isabel

    We present results from a Fabry-Perot study of the Hα velocity fields and morphologies of a sample of luminous blue compact galaxies. We estimate masses from photometry and kinematics and show that many of these BCGs are not rotationally supported. Mergers or strong interactions appear to be the triggering mechanism of the extreme starbursts seen in these galaxies.

  18. Detailed stellar and gaseous kinematics of M31

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  19. Camera-Only Kinematics for Small Lunar Rovers

    NASA Astrophysics Data System (ADS)

    Fang, E.; Suresh, S.; Whittaker, W.

    2016-11-01

    Knowledge of the kinematic state of rovers is critical. Existing methods add sensors and wiring to moving parts, which can fail and adds mass and volume. This research presents a method to optically determine kinematic state using a single camera.

  20. Inverse Problems of Thermoelectricity

    NASA Astrophysics Data System (ADS)

    Anatychuk, L. I.; Luste, O. J.; Kuz, R. V.; Strutinsky, M. N.

    2011-05-01

    Classical thermoelectricity is based on the use of the Seebeck and Thomson effects that occur in the near-contact areas between n- and p-type materials. A conceptually different approach to thermoelectric power converter design that is based on the law of thermoelectric induction of currents is also known. The efficiency of this approach has already been demonstrated by its first applications. More than 10 basically new types of thermoelements were discovered with properties that cannot be achieved by thermocouple power converters. Therefore, further development of this concept is of practical interest. This paper provides a classification and theory for solving the inverse problems of thermoelectricity that form the basis for devising new thermoelement types. Computer methods for their solution for anisotropic and inhomogeneous media are elaborated. Regularities related to thermoelectric current excitation in anisotropic and inhomogeneous media are established. The possibility of obtaining eddy currents of a particular configuration through control of the temperature field and material parameters for the creation of new thermo- element types is demonstrated for three-dimensional (3D) models of anisotropic and inhomogeneous media.

  1. Inverse problem in hydrogeology

    NASA Astrophysics Data System (ADS)

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

    2005-03-01

    The state of the groundwater inverse problem is synthesized. Emphasis is placed on aquifer characterization, where modelers have to deal with conceptual model uncertainty (notably spatial and temporal variability), scale dependence, many types of unknown parameters (transmissivity, recharge, boundary conditions, etc.), nonlinearity, and often low sensitivity of state variables (typically heads and concentrations) to aquifer properties. Because of these difficulties, calibration cannot be separated from the modeling process, as it is sometimes done in other fields. Instead, it should be viewed as one step in the process of understanding aquifer behavior. In fact, it is shown that actual parameter estimation methods do not differ from each other in the essence, though they may differ in the computational details. It is argued that there is ample room for improvement in groundwater inversion: development of user-friendly codes, accommodation of variability through geostatistics, incorporation of geological information and different types of data (temperature, occurrence and concentration of isotopes, age, etc.), proper accounting of uncertainty, etc. Despite this, even with existing codes, automatic calibration facilitates enormously the task of modeling. Therefore, it is contended that its use should become standard practice. L'état du problème inverse des eaux souterraines est synthétisé. L'accent est placé sur la caractérisation de l'aquifère, où les modélisateurs doivent jouer avec l'incertitude des modèles conceptuels (notamment la variabilité spatiale et temporelle), les facteurs d'échelle, plusieurs inconnues sur différents paramètres (transmissivité, recharge, conditions aux limites, etc.), la non linéarité, et souvent la sensibilité de plusieurs variables d'état (charges hydrauliques, concentrations) des propriétés de l'aquifère. A cause de ces difficultés, le calibrage ne peut êtreséparé du processus de modélisation, comme c'est le

  2. Polarization of inverse plasmon scattering

    NASA Technical Reports Server (NTRS)

    Windsor, R. A.; Kellogg, P. J.

    1974-01-01

    The scattering of electrostatic plasma waves by a flux of ultrarelativistic electrons passing through a plasma gives rise to a radiation spectrum which is similar to a synchrotron radiation spectrum. This mechanism, first considered by Gailitis and Tsytovich, is analagous to inverse Compton scattering, and we have named it inverse plasmon scattering. For a power-law electron flux, both inverse plasmon scattering and synchrotron radiation have the same spectral index. In an attempt to distinguish between these mechanisms, we have calculated the polarization level expected from inverse plasmon scattering. The polarization level found is similar to that obtained from a synchrotron radiation source. This means that the radiation produced by two mechanisms, synchrotron radiation and inverse plasmon scattering, is indistinguishable; and this attempt to differentiate between them by polarization effects has been unsuccessful.

  3. The Maiden Voyage of a Kinematics Robot

    NASA Astrophysics Data System (ADS)

    Greenwolfe, Matthew L.

    2015-04-01

    In a Montessori preschool classroom, students work independently on tasks that absorb their attention in part because the apparatus are carefully designed to make mistakes directly observable and limit exploration to one aspect or dimension. Control of error inheres in the apparatus itself, so that teacher intervention can be minimal.1 Inspired by this example, I created a robotic kinematics apparatus that also shapes the inquiry experience. Students program the robot by drawing kinematic graphs on a computer and then observe its motion. Exploration is at once limited to constant velocity and constant acceleration motion, yet open to complex multi-segment examples difficult to achieve in the lab in other ways. The robot precisely and reliably produces the motion described by the students' graphs, so that the apparatus itself provides immediate visual feedback about whether their understanding is correct as they are free to explore within the hard-coded limits. In particular, the kinematic robot enables hands-on study of multi-segment constant velocity situations, which lays a far stronger foundation for the study of accelerated motion. When correction is anonymous—just between one group of lab partners and their robot—students using the kinematic robot tend to flow right back to work because they view the correction as an integral part of the inquiry learning process. By contrast, when correction occurs by the teacher and/or in public (e.g., returning a graded assignment or pointing out student misconceptions during class), students all too often treat the event as the endpoint to inquiry. Furthermore, quantitative evidence shows a large gain from pre-test to post-test scores using the Test of Understanding Graphs in Kinematics (TUG-K).

  4. Kinematic Downsizing at z ∼ 2

    NASA Astrophysics Data System (ADS)

    Simons, Raymond C.; Kassin, Susan A.; Trump, Jonathan R.; Weiner, Benjamin J.; Heckman, Timothy M.; Barro, Guillermo; Koo, David C.; Guo, Yicheng; Pacifici, Camilla; Koekemoer, Anton; Stephens, Andrew W.

    2016-10-01

    We present results from a survey of the internal kinematics of 49 star-forming galaxies at z∼ 2 in the CANDELS fields with the Keck/MOSFIRE spectrograph, Survey in the near-Infrared of Galaxies with Multiple position Angles (SIGMA). Kinematics (rotation velocity V rot and gas velocity dispersion {σ }g) are measured from nebular emission lines which trace the hot ionized gas surrounding star-forming regions. We find that by z∼ 2, massive star-forming galaxies ({log} {M}* /{M}ȯ ≳ 10.2) have assembled primitive disks: their kinematics are dominated by rotation, they are consistent with a marginally stable disk model, and they form a Tully–Fisher relation. These massive galaxies have values of {V}{rot}/{σ }g that are factors of 2–5 lower than local well-ordered galaxies at similar masses. Such results are consistent with findings by other studies. We find that low-mass galaxies ({log} {M}* /{M}ȯ ≲ 10.2) at this epoch are still in the early stages of disk assembly: their kinematics are often dominated by gas velocity dispersion and they fall from the Tully–Fisher relation to significantly low values of V rot. This “kinematic downsizing” implies that the process(es) responsible for disrupting disks at z∼ 2 have a stronger effect and/or are more active in low-mass systems. In conclusion, we find that the period of rapid stellar mass growth at z∼ 2 is coincident with the nascent assembly of low-mass disks and the assembly and settling of high-mass disks.

  5. Kinematic Optimization in Birds, Bats and Ornithopters

    NASA Astrophysics Data System (ADS)

    Reichert, Todd

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

  6. Three-dimensional kinematics of hummingbird flight.

    PubMed

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

    2007-07-01

    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.

  7. Absolute magnitudes and kinematics of barium stars.

    NASA Astrophysics Data System (ADS)

    Gomez, A. E.; Luri, X.; Grenier, S.; Prevot, L.; Mennessier, M. O.; Figueras, F.; Torra, J.

    1997-03-01

    The absolute magnitude of barium stars has been obtained from kinematical data using a new algorithm based on the maximum-likelihood principle. The method allows to separate a sample into groups characterized by different mean absolute magnitudes, kinematics and z-scale heights. It also takes into account, simultaneously, the censorship in the sample and the errors on the observables. The method has been applied to a sample of 318 barium stars. Four groups have been detected. Three of them show a kinematical behaviour corresponding to disk population stars. The fourth group contains stars with halo kinematics. The luminosities of the disk population groups spread a large range. The intrinsically brightest one (M_v_=-1.5mag, σ_M_=0.5mag) seems to be an inhomogeneous group containing barium binaries as well as AGB single stars. The most numerous group (about 150 stars) has a mean absolute magnitude corresponding to stars in the red giant branch (M_v_=0.9mag, σ_M_=0.8mag). The third group contains barium dwarfs, the obtained mean absolute magnitude is characteristic of stars on the main sequence or on the subgiant branch (M_v_=3.3mag, σ_M_=0.5mag). The obtained mean luminosities as well as the kinematical results are compatible with an evolutionary link between barium dwarfs and classical barium giants. The highly luminous group is not linked with these last two groups. More high-resolution spectroscopic data will be necessary in order to better discriminate between barium and non-barium stars.

  8. A non-recursive Lagrangian solution of the non-causal inverse dynamics of flexible multibody systems - The planar case

    NASA Astrophysics Data System (ADS)

    Ledesma, Ragnar; Bayo, Eduardo

    1993-08-01

    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.

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

    ERIC Educational Resources Information Center

    Trumper, Ricardo

    1997-01-01

    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…

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

    ERIC Educational Resources Information Center

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

    2011-01-01

    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…

  11. Tongue-jaw kinematic correlates of /s/ spectra

    NASA Astrophysics Data System (ADS)

    Dembowski, James S.; Crumb, Richard K.

    2001-05-01

    Frequencies of spectral peaks for fricatives are determined by the size of the resonating cavity anterior to the place of articulatory constriction in the upper vocal tract. For /s/, this cavity size may be altered through anterior-posterior (a-p) movements of the tongue blade forming the constriction, changes of jaw height, and degree of lip protrusion. With respect to intensity, modeling studies suggest that intensity of fricative spectral peaks may be related to degree of articulatory constriction. These spectral-kinematic relationships have been little studied in natural speech. This study used data from the University of Wisconsin X-Ray Microbeam Database to examine the relationship between spectral peaks and movements of the tongue and jaw in the /s/ productions of one normal speaker. Results showed no relationship between a-p tongue position and frequency of spectral peaks. However, a significant inverse correlation related peak between frequency and jaw opening. Thus, for this speaker jaw height appeared a more important determinant of spectral variability for /s/ than tongue position. Additional results showed a significant relationship between peak intensity and distance of the tongue blade from the palate. These natural speech data will be discussed with respect to models and theories of fricative production.

  12. Stylolite stress inversion

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  13. Microwave inverse Cerenkov accelerator

    NASA Astrophysics Data System (ADS)

    Zhang, T. B.; Marshall, T. C.; LaPointe, M. A.; Hirshfield, J. L.

    1997-03-01

    A Microwave Inverse Cerenkov Accelerator (MICA) is currently under construction at the Yale Beam Physics Laboratory. The accelerating structure in MICA consists of an axisymmetric dielectrically lined waveguide. For the injection of 6 MeV microbunches from a 2.856 GHz RF gun, and subsequent acceleration by the TM01 fields, particle simulation studies predict that an acceleration gradient of 6.3 MV/m can be achieved with a traveling-wave power of 15 MW applied to the structure. Synchronous injection into a narrow phase window is shown to allow trapping of all injected particles. The RF fields of the accelerating structure are shown to provide radial focusing, so that longitudinal and transverse emittance growth during acceleration is small, and that no external magnetic fields are required for focusing. For 0.16 nC, 5 psec microbunches, the normalized emittance of the accelerated beam is predicted to be less than 5πmm-mrad. Experiments on sample alumina tubes have been conducted that verify the theoretical dispersion relation for the TM01 mode over a two-to-one range in frequency. No excitation of axisymmetric or non-axisymmetric competing waveguide modes was observed. High power tests showed that tangential electric fields at the inner surface of an uncoated sample of alumina pipe could be sustained up to at least 8.4 MV/m without breakdown. These considerations suggest that a MICA test accelerator can be built to examine these predictions using an available RF power source, 6 MeV RF gun and associated beam line.

  14. Temperature inversion in China seas

    NASA Astrophysics Data System (ADS)

    Hao, Jiajia; Chen, Yongli; Wang, Fan

    2010-12-01

    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 remarkable with obvious temporal and spatial variabilities in both magnitude and coverage, with higher probabilities in region A (up to about 60%) and region C (40%-50%) than in region B (15%-20%). The analysis shows that seasonal variation of the net air-sea heat flux is closely related to the occurrence time of the inversion in the three areas, while the Yangtze and Yellow river freshwater plumes in the surface layer and ocean origin saline water in the subsurface layer maintain stable stratification. It seems that the evaporation/excessive precipitation flux makes little contribution to maintaining the stable inversion. Advection of surface fresh water by the wind-driven coastal currents results in the expansion of inversion in regions A and C. The inversion lasts for the longest period in region A (October-May) sustained by the Taiwan Warm Current carrying the subsurface saline water, while evolution of the inversion in region B is mainly controlled by the Yellow Sea Warm Current.

  15. Inversion of Attributes and Full Waveforms of Ground Penetrating Radar Data Using PEST

    NASA Astrophysics Data System (ADS)

    Jazayeri, S.; Kruse, S.; Esmaeili, S.

    2015-12-01

    We seek to establish a method, based on freely available software, for inverting GPR signals for the underlying physical properties (electrical permittivity, magnetic permeability, target geometries). Such a procedure should be useful for classroom instruction and for analyzing surface GPR surveys over simple targets. We explore the applicability of the PEST parameter estimation software package for GPR inversion (www.pesthomepage.org). PEST is designed to invert data sets with large numbers of parameters, and offers a variety of inversion methods. Although primarily used in hydrogeology, the code has been applied to a wide variety of physical problems. The PEST code requires forward model input; the forward model of the GPR signal is done with the GPRMax package (www.gprmax.com). The problem of extracting the physical characteristics of a subsurface anomaly from the GPR data is highly nonlinear. For synthetic models of simple targets in homogeneous backgrounds, we find PEST's nonlinear Gauss-Marquardt-Levenberg algorithm is preferred. This method requires an initial model, for which the weighted differences between model-generated data and those of the "true" synthetic model (the objective function) are calculated. In order to do this, the Jacobian matrix and the derivatives of the observation data in respect to the model parameters are computed using a finite differences method. Next, the iterative process of building new models by updating the initial values starts in order to minimize the objective function. Another measure of the goodness of the final acceptable model is the correlation coefficient which is calculated based on the method of Cooley and Naff. An accepted final model satisfies both of these conditions. Models to date show that physical properties of simple isolated targets against homogeneous backgrounds can be obtained from multiple traces from common-offset surface surveys. Ongoing work examines the inversion capabilities with more complex

  16. Why does inverse modeling of drainage inventories work?

    NASA Astrophysics Data System (ADS)

    White, Nicky; Roberts, Gareth

    2016-04-01

    We describe and apply a linear inverse model which calculates spatial and temporal patterns of uplift rate by minimizing the misfit between inventories of observed and predicted longitudinal river profiles. This approach builds upon a more general, non-linear, optimization model, which suggests that shapes of river profiles are dominantly controlled by upstream advection of kinematic waves of incision produced by spatial and temporal changes in regional uplift rate. We have tested both algorithms by inverting thousands of river profiles from Africa, Eurasia, the Americas, and Australia. For each continent, the drainage network was constructed from a digital elevation model and the fidelity of river profiles extracted from this network was carefully checked using satellite imagery. Spatial and temporal patterns of both uplift rate and cumulative uplift were calibrated using independent geologic and geophysical observations. Inverse modeling of these substantial inventories of river profiles suggests that drainage networks contain coherent signals that record the regional growth of elevation. In the second part of this presentation, we use spectral analysis of river profiles to suggest why drainage networks behave in a coherent, albeit non-linear, fashion. Our analysis implies that large-scale topographic signals injected into landscapes generate spectral slopes that are usually red (i.e. Brownian). At wavelengths shorter than tens of km, spectral slopes whiten which suggests that coherent topographic signals cease to exist at these shorter length scales. Our results suggest that inverse modeling of drainage networks can reveal useful information about landscape growth through space and time.

  17. Goal Directed Model Inversion: A Study of Dynamic Behavior

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    Goal Directed Model Inversion (GDMI) is an algorithm designed to generalize supervised learning to the case where target outputs are not available to the learning system. The output of the learning system becomes the input to some external device or transformation, and only the output of this device or transformation can be compared to a desired target. The fundamental driving mechanism of GDMI is to learn from success. Given that a wrong outcome is achieved, one notes that the action that produced that outcome 0 "would have been right if the outcome had been the desired one." The algorithm then proceeds as follows: (1) store the action that produced the wrong outcome as a "target" (2) redefine the wrong outcome as a desired goal (3) submit the new desired goal to the system (4) compare the new action with the target action and modify the system by using a suitable algorithm for credit assignment (Back propagation in our example) (5) resubmit the original goal. Prior publications by our group in this area focused on demonstrating empirical results based on the inverse kinematic problem for a simulated robotic arm. In this paper we apply the inversion process to much simpler analytic functions in order to elucidate the dynamic behavior of the system and to determine the sensitivity of the learning process to various parameters. This understanding will be necessary for the acceptance of GDMI as a practical tool.

  18. Givental Graphs and Inversion Symmetry

    NASA Astrophysics Data System (ADS)

    Dunin-Barkowski, Petr; Shadrin, Sergey; Spitz, Loek

    2013-05-01

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

  19. Performance of ionospheric maps in support of long baseline GNSS kinematic positioning at low latitudes

    NASA Astrophysics Data System (ADS)

    Park, J.; Sreeja, V.; Aquino, M.; Cesaroni, C.; Spogli, L.; Dodson, A.; De Franceschi, G.

    2016-05-01

    Ionospheric scintillation occurs mainly at high and low latitude regions of the Earth and may impose serious degradation on GNSS (Global Navigation Satellite System) functionality. The Brazilian territory sits on one of the most affected areas of the globe, where the ionosphere behaves very unpredictably, with strong scintillation frequently occurring in the local postsunset hours. The correlation between scintillation occurrence and sharp variations in the ionospheric total electron content (TEC) in Brazil is demonstrated in Spogli et al. (2013). The compounded effect of these associated ionospheric disturbances on long baseline GNSS kinematic positioning is studied in this paper, in particular when ionospheric maps are used to aid the positioning solution. The experiments have been conducted using data from GNSS reference stations in Brazil. The use of a regional TEC map generated under the CALIBRA (Countering GNSS high-Accuracy applications Limitations due to Ionospheric disturbances in BRAzil) project, referred to as CALIBRA TEC map (CTM), was compared to the use of the Global Ionosphere Map (GIM), provided by the International GNSS Service (IGS). Results show that the use of the CTM greatly improves the kinematic positioning solution as compared with that using the GIM, especially under disturbed ionospheric conditions. Additionally, different hypotheses were tested regarding the precision of the TEC values obtained from ionospheric maps, and its effect on the long baseline kinematic solution evaluated. Finally, this study compares two interpolation methods for ionospheric maps, namely, the Inverse Distance Weight and the Natural Neighbor.

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

    PubMed Central

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

    2012-01-01

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

  1. 3D kinematics using dual quaternions: theory and applications in neuroscience

    PubMed Central

    Leclercq, Guillaume; Lefèvre, Philippe; Blohm, Gunnar

    2013-01-01

    In behavioral neuroscience, many experiments are developed in 1 or 2 spatial dimensions, but when scientists tackle problems in 3-dimensions (3D), they often face problems or new challenges. Results obtained for lower dimensions are not always extendable in 3D. In motor planning of eye, gaze or arm movements, or sensorimotor transformation problems, the 3D kinematics of external (stimuli) or internal (body parts) must often be considered: how to describe the 3D position and orientation of these objects and link them together? We describe how dual quaternions provide a convenient way to describe the 3D kinematics for position only (point transformation) or for combined position and orientation (through line transformation), easily modeling rotations, translations or screw motions or combinations of these. We also derive expressions for the velocities of points and lines as well as the transformation velocities. Then, we apply these tools to a motor planning task for manual tracking and to the modeling of forward and inverse kinematics of a seven-dof three-link arm to show the interest of dual quaternions as a tool to build models for these kinds of applications. PMID:23443667

  2. Source Inversion Validation: Quantifying Uncertainties in Earthquake Source Inversions

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  3. Inversion of geothermal heat flux in a thermomechanically coupled nonlinear Stokes ice sheet model

    NASA Astrophysics Data System (ADS)

    Zhu, Hongyu; Petra, Noemi; Stadler, Georg; Isaac, Tobin; Hughes, Thomas J. R.; Ghattas, Omar

    2016-07-01

    We address the inverse problem of inferring the basal geothermal heat flux from surface velocity observations using a steady-state thermomechanically coupled nonlinear Stokes ice flow model. This is a challenging inverse problem since the map from basal heat flux to surface velocity observables is indirect: the heat flux is a boundary condition for the thermal advection-diffusion equation, which couples to the nonlinear Stokes ice flow equations; together they determine the surface ice flow velocity. This multiphysics inverse problem is formulated as a nonlinear least-squares optimization problem with a cost functional that includes the data misfit between surface velocity observations and model predictions. A Tikhonov regularization term is added to render the problem well posed. We derive adjoint-based gradient and Hessian expressions for the resulting partial differential equation (PDE)-constrained optimization problem and propose an inexact Newton method for its solution. As a consequence of the Petrov-Galerkin discretization of the energy equation, we show that discretization and differentiation do not commute; that is, the order in which we discretize the cost functional and differentiate it affects the correctness of the gradient. Using two- and three-dimensional model problems, we study the prospects for and limitations of the inference of the geothermal heat flux field from surface velocity observations. The results show that the reconstruction improves as the noise level in the observations decreases and that short-wavelength variations in the geothermal heat flux are difficult to recover. We analyze the ill-posedness of the inverse problem as a function of the number of observations by examining the spectrum of the Hessian of the cost functional. Motivated by the popularity of operator-split or staggered solvers for forward multiphysics problems - i.e., those that drop two-way coupling terms to yield a one-way coupled forward Jacobian - we study the

  4. Kinematics of Earth Impacting Coronal Mass Ejections

    NASA Astrophysics Data System (ADS)

    Colaninno, R. C.; Vourlidas, A.

    2012-12-01

    With the data from the STEREO mission, we are able to continuously monitor Coronal Mass Ejections (CMEs) as they progress from the Sun to Earth. However, even with continuous monitoring with remote sensing observations, we are still unable to accurately predict the arrival or terrestrial impact of a CME. In this study, we analyze nine CMEs from the Sun to Earth as observed in both the remote sensing and in situ data sets. In this study, we track nine CMEs from the Sun to 70% - 98% of the distance to Earth with the remote sensing data. We use the Graduate Cyclical Shell (GCS) model to estimate the position of each CME as it is observed in the inner heliosphere. From the derived kinematics, we compare the predicted arrival times and impact velocities with the in situ data. We consider different method for fitting the kinematics and the modeled geometry of the CME to improve the predicted arrival time.

  5. The kinematic advantage of electric cars

    NASA Astrophysics Data System (ADS)

    Meyn, Jan-Peter

    2015-11-01

    Acceleration of a common car with with a turbocharged diesel engine is compared to the same type with an electric motor in terms of kinematics. Starting from a state of rest, the electric car reaches a distant spot earlier than the diesel car, even though the latter has a better specification for engine power and average acceleration from 0 to 100 km h-1. A three phase model of acceleration as a function of time fits the data of the electric car accurately. The first phase is a quadratic growth of acceleration in time. It is shown that the tenfold higher coefficient for the first phase accounts for most of the kinematic advantage of the electric car.

  6. On the kinematic age of RZ Psc

    NASA Astrophysics Data System (ADS)

    Potravnov, I. S.; Grinin, V. P.

    2013-11-01

    RZ Psc belongs to the family of young UX Ori stars whose photometric activity is due to strong extinction variations in the circumstellar disks surrounding them. However, in contrast to all the remaining stars of this type, no evidence of youth has been detected for RZ Psc until recently. A rough estimate of the star's kinematic age was made for the first time in our previous paper (Grinin et al. 2010). It shows that RZ Psc is intermediate in its evolutionary status between young stars in Orion and stars with debris disks. In this paper, we provide a refined estimate of the kinematic age for the star confirming this conclusion. According to this estimate, the age of RZ Psc is approximately 25 ± 5 Myr at M * = 1 M ⊙.

  7. Kinematic measurements using an infrared sensor

    NASA Astrophysics Data System (ADS)

    Marinho, F.; Paulucci, L.

    2016-03-01

    The use of an infrared sensor as a new alternative to measure position as a function of time in kinematic experiments was investigated using a microcontroller as the data acquisition and control device. These are versatile sensors that offer advantages over typical ultrasound devices. The setup described in this paper enables students to develop their own experiments, promoting opportunities for learning physical concepts such as the different types of forces that can act on a body (gravitational, elastic, drag, etc) and the resulting types of movements with good sensitivity within the 4-30 cm range. As a proof of concept we also present the application of a prototype designed to record the kinematics of mass-spring systems.

  8. Plasma electron hole kinematics. I. Momentum conservation

    NASA Astrophysics Data System (ADS)

    Hutchinson, I. H.; Zhou, C.

    2016-08-01

    We analyse the kinematic properties of a plasma electron hole: a non-linear self-sustained localized positive electric potential perturbation, trapping electrons, which behaves as a coherent entity. When a hole accelerates or grows in depth, ion and electron plasma momentum is changed both within the hole and outside, by an energization process we call jetting. We present a comprehensive analytic calculation of the momentum changes of an isolated general one-dimensional hole. The conservation of the total momentum gives the hole's kinematics, determining its velocity evolution. Our results explain many features of the behavior of hole speed observed in numerical simulations, including self-acceleration at formation, and hole pushing and trapping by ion streams.

  9. Kinematics of the symbiotic system R Aqr

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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], (λc = 6575Å, Δλ = 90Å). We analyse the [NII] λλ6583 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.

  10. The kinematic origin of the cosmological redshift

    NASA Astrophysics Data System (ADS)

    Bunn, Emory F.; Hogg, David W.

    2009-08-01

    A common belief about big-bang cosmology is that the cosmological redshift cannot be properly viewed as a Doppler shift (that is, as evidence for a recession velocity) but must be viewed in terms of the stretching of space. We argue that, contrary to this view, the most natural interpretation of the redshift is as a Doppler shift, or rather as the accumulation of many infinitesimal Doppler shifts. The stretching-of-space interpretation obscures a central idea of relativity, namely that it is always valid to choose a coordinate system that is locally Minkowskian. We show that an observed frequency shift in any spacetime can be interpreted either as a kinematic (Doppler) shift or a gravitational shift by imagining a suitable family of observers along the photon's path. In the context of the expanding universe, the kinematic interpretation corresponds to a family of comoving observers and hence is more natural.

  11. Uterine Inversion; A case report.

    PubMed

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

    2008-01-01

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

  12. Uterine Inversion; A case report

    PubMed Central

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

    2008-01-01

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

  13. Donor states in inverse opals

    SciTech Connect

    Mahan, G. D.

    2014-09-21

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

  14. Inversion layer MOS solar cells

    NASA Technical Reports Server (NTRS)

    Ho, Fat Duen

    1986-01-01

    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.

  15. Temperature Inversions Have Cold Bottoms.

    ERIC Educational Resources Information Center

    Bohren, Craig F.; Brown, Gail M.

    1982-01-01

    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)

  16. Donor states in inverse opals

    NASA Astrophysics Data System (ADS)

    Mahan, G. D.

    2014-09-01

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

  17. Moebius inversion formula and inverting lattice sums

    NASA Astrophysics Data System (ADS)

    Millane, Rick P.

    2000-11-01

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

  18. Kinematics of Hooke universal joint robot wrists

    NASA Technical Reports Server (NTRS)

    Mckinney, William S., Jr.

    1988-01-01

    The singularity problem associated with wrist mechanisms commonly found on industrial manipulators can be alleviated by redesigning the wrist so that it functions as a three-axis gimbal system. This paper discussess the kinematics of gimbal robot wrists made of one and two Hooke universal joints. Derivations of the resolved rate motion control equations for the single and double Hooke universal joint wrists are presented using the three-axis gimbal system as a theoretical wrist model.

  19. Kinematics and dynamics of sphenisciform wings

    NASA Astrophysics Data System (ADS)

    Noca, Flavio; Crisinel, Fabien; Munier, Pierre

    2011-11-01

    Three-dimensional scans of three different species of taxidermied penguins (Aptenodytes patagonicus, Pygoscelis papua, and Spheniscus magellanicus) have been performed. A three-dimensional reproduction of an African penguin (Sphenicus demersus) wing was manufactured and tested in a hydrodynamic channel. A six-degree-of-freedom robot was programmed to perform the three dimensional kinematics, obtained from actual footage. A six-component force balance was used to retrieve the dynamics of the wing motion. Results will be presented and discussed.

  20. Lower extremity kinematics of athletics curve sprinting.

    PubMed

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

    2015-01-01

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

  1. Scapula Kinematics of Youth Baseball Players

    PubMed Central

    Oliver, Gretchen; Weimar, Wendi

    2015-01-01

    Literature has revealed the importance of quantifying resting scapular posture in overhead athletes as well as quantifying scapular kinematics during dynamic movement. Prior to this project much of the attention in throwing research had been focused on the position of the humerus without description of the positioning of the scapula. Therefore, it was the purpose of this study to present scapular kinematics during pitching in youth baseball players. Twenty-five youth baseball players (age 11.3 + 1.0 years; body height 152.4 + 9.0 cm; body mass 47.5 + 11.3 kg), with no history of injury, participated in the study. Scapular kinematics at the events of maximum humeral external rotation (MER) and maximum humeral internal rotation (MIR) during the pitching motion were assessed three-dimensionally while pitching fastballs for strikes. Results revealed that at the event of MER, the scapula was in a position of retraction, upward rotation and a posterior tilt. While at the event of MIR, the scapula was protracted, upward rotated and tilted anteriorly. PMID:26839605

  2. Scapula Kinematics of Youth Baseball Players.

    PubMed

    Oliver, Gretchen; Weimar, Wendi

    2015-12-22

    Literature has revealed the importance of quantifying resting scapular posture in overhead athletes as well as quantifying scapular kinematics during dynamic movement. Prior to this project much of the attention in throwing research had been focused on the position of the humerus without description of the positioning of the scapula. Therefore, it was the purpose of this study to present scapular kinematics during pitching in youth baseball players. Twenty-five youth baseball players (age 11.3 + 1.0 years; body height 152.4 + 9.0 cm; body mass 47.5 + 11.3 kg), with no history of injury, participated in the study. Scapular kinematics at the events of maximum humeral external rotation (MER) and maximum humeral internal rotation (MIR) during the pitching motion were assessed three-dimensionally while pitching fastballs for strikes. Results revealed that at the event of MER, the scapula was in a position of retraction, upward rotation and a posterior tilt. While at the event of MIR, the scapula was protracted, upward rotated and tilted anteriorly.

  3. New Kinematical Constraints on Cosmic Acceleration

    SciTech Connect

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

    2007-05-25

    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.

  4. Circadian rhythms in handwriting kinematics and legibility.

    PubMed

    Jasper, Isabelle; Gordijn, Marijke; Häussler, Andreas; Hermsdörfer, Joachim

    2011-08-01

    The aim of the present study was to analyze the circadian rhythmicity in handwriting kinematics and legibility and to compare the performance between Dutch and German writers. Two subject groups underwent a 40 h sleep deprivation protocol under Constant Routine conditions either in Groningen (10 Dutch subjects) or in Berlin (9 German subjects). Both groups wrote every 3h a test sentence of similar structure in their native language. Kinematic handwriting performance was assessed with a digitizing tablet and evaluated by writing speed, writing fluency, and script size. Writing speed (frequency of strokes and average velocity) revealed a clear circadian rhythm, with a parallel decline during night and a minimum around 3:00 h in the morning for both groups. Script size and movement fluency did not vary with time of day in neither group. Legibility of handwriting was evaluated by intra-individually ranking handwriting specimens of the 13 sessions by 10 German and 10 Dutch raters. Whereas legibility ratings of the German handwriting specimens deteriorated during night in parallel with slower writing speed, legibility of the Dutch handwriting deteriorated not until the next morning. In conclusion, the circadian rhythm of handwriting kinematics seems to be independent of script language at least among the two tested western countries. Moreover, handwriting legibility is also subject to a circadian rhythm which, however, seems to be influenced by variations in the assessment protocol.

  5. Scapula Kinematics of Youth Baseball Players.

    PubMed

    Oliver, Gretchen; Weimar, Wendi

    2015-12-22

    Literature has revealed the importance of quantifying resting scapular posture in overhead athletes as well as quantifying scapular kinematics during dynamic movement. Prior to this project much of the attention in throwing research had been focused on the position of the humerus without description of the positioning of the scapula. Therefore, it was the purpose of this study to present scapular kinematics during pitching in youth baseball players. Twenty-five youth baseball players (age 11.3 + 1.0 years; body height 152.4 + 9.0 cm; body mass 47.5 + 11.3 kg), with no history of injury, participated in the study. Scapular kinematics at the events of maximum humeral external rotation (MER) and maximum humeral internal rotation (MIR) during the pitching motion were assessed three-dimensionally while pitching fastballs for strikes. Results revealed that at the event of MER, the scapula was in a position of retraction, upward rotation and a posterior tilt. While at the event of MIR, the scapula was protracted, upward rotated and tilted anteriorly. PMID:26839605

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

    SciTech Connect

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

    1997-03-01

    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.

  7. Kinematics of Haro 11: The miniature Antennae

    NASA Astrophysics Data System (ADS)

    Östlin, G.; Marquart, T.; Cumming, R. J.; Fathi, K.; Bergvall, N.; Adamo, A.; Amram, P.; Hayes, M.

    2015-11-01

    Luminous blue compact galaxies are among the most active galaxies in the local Universe in terms of their star formation rate per unit mass. They are rare at the current cosmic epoch, but were more abundant in the past and may be seen as the local analogues of higher red shift Lyman break galaxies. Studies of their kinematics is key to understanding what triggers their unusually active star formation. In this work, we investigate the kinematics of stars and ionised gas in Haro 11, one of the most luminous blue compact galaxies in the local Universe. Previous works have indicated that many of these galaxies may be triggered by galaxy mergers. We have employed Fabry-Perot interferometry, long-slit spectroscopy, and integral field unit (IFU) spectroscopy to explore the kinematics of Haro 11. We target the near-infrared calcium triplet, and use cross-correlation and penalised pixel fitting techniques to derive the stellar velocity field and velocity dispersion. We analyse ionised gas through emission lines from hydrogen, [O iii], and [S iii]. When spectral resolution and signal to noise allows, we investigate the line profile in detail and identify multiple velocity components when present. The spectra reveal a complex velocity field whose components, both stellar and gaseous, we attempt to disentangle. We find that to first order, the velocity field and velocity dispersions derived from stars and ionised gas agree. Hence the complexities reveal real dynamical disturbances providing further evidence for a merger in Haro 11. Through decomposition of emission lines, we find evidence for kinematically distinct components, for instance, a tidal arm. The ionised gas velocity field can be traced to large galactocentric radii, and shows significant velocity dispersion even far out in the halo. If interpreted as virial motions, this indicates that Haro 11 may have a mass of ~1011 M⊙. Haro 11 shows many resemblances with the famous Antennae galaxies both morphologically and

  8. The Kinematics and Dynamics of SA Galaxies

    NASA Astrophysics Data System (ADS)

    Jore, Katherine Patricia

    1997-12-01

    A study of the kinematics of the stellar and gaseous components of Sa galaxies was undertaken in order to understand the origins of the heterogeneity of the Sa galaxies as a class and to investigate previous observations suggesting that the fraction of the mass of Sa galaxies in the form of dark matter is smaller than that found in later type spirals. A sample of 23 nearby non-interacting morphologically normal galaxies was studied. The small-bulged Sa, NGC 4138, was found to contain two extended counter-rotating stellar disks. The primary stellar disk contains ~80% of the stars; the presence of Hα absorption suggests that star formation in this component ceased ~108 years ago. The remaining stars, along with the H I and emission line gas, are rotating counter to the primary disk with comparable observed velocity. The counter-rotating disk may either be the result of a merger of a spiral with a gas-rich dwarf, or the continual infall of material of opposite spin vector onto the galaxy. For the entire sample, comparison of the stellar and optical rotation curves reveals that only 4 of the 23 galaxies in the sample are free of kinematic peculiarities. Eighteen galaxies in the sample have non-circular motions along the minor axis. Along the major axis, 11 galaxies have kinematic peculiarities including extended counter-rotating stars and∨ gas, counter-rotating stellar or gas cores, or multiple stellar or gas components. The presence of kinematically decoupled components suggests that minor mergers may have been common events even among morphologically normal Sa's. Dynamical masses were obtained from the velocity fields mapped by optical and H I observations by adopting the maximum disk hypothesis. As in previous studies, the kinematics of most Sa galaxies can be modeled within the optical disk without invoking a significant dark matter halo component. However, in order to model the velocity fields as traced by the H I sizable dark matter halo components are

  9. The Stellar Kinematic Fields of NGC 3379

    NASA Astrophysics Data System (ADS)

    Statler, Thomas S.; Smecker-Hane, Tammy

    1999-02-01

    We have measured the stellar kinematic profiles of NGC 3379 along four position angles, using absorption lines in spectra obtained with the Multiple Mirror Telescope. We derive a far more detailed description of the kinematic fields through the main body of the galaxy than could be obtained from previous work. Our data extend 90" from the center, at essentially seeing-limited resolution out to 17". The derived mean velocities and dispersions have total errors (internal and systematic) better than +/-10 km s^-1, and frequently better than 5 km s^-1, out to 55". We find very weak (3 km s^-1) rotation on the minor axis interior to 12" and no detectable rotation above 6 km s^-1 from 12" to 50" or above 16 km s^-1 out to 90" (95% confidence limits). However, a Fourier reconstruction of the mean velocity field from all four sampled PAs does indicate a ~5 deg twist of the kinematic major axis, in the direction opposite to the known isophotal twist. The h_3 and h_4 parameters are found to be generally small over the entire observed region. The azimuthally averaged dispersion profile joins smoothly at large radii with the velocity dispersions of planetary nebulae. Unexpectedly, we find sharp bends in the major axis rotation curve, also visible (though less pronounced) on the diagonal position angles. The outermost bend closely coincides in position with other sharp kinematic features: an abrupt flattening of the dispersion profile, and local peaks in h_3 and h_4. All of these features are in a photometrically interesting region in which the surface brightness profile departs significantly from an r^1/4 law. Features such as these are not generally known in elliptical galaxies owing to a lack of data at comparable resolution. Very similar behavior, however, is seen the kinematics of the edge-on S0 galaxy NGC 3115. We discuss the suggestion that NGC 3379 could be a misclassified S0 galaxy; preliminary results from dynamical modeling indicate that it may be a flattened, weakly

  10. Multidimensional NMR inversion without Kronecker products: Multilinear inversion.

    PubMed

    Medellín, David; Ravi, Vivek R; Torres-Verdín, Carlos

    2016-08-01

    Multidimensional NMR inversion using Kronecker products poses several challenges. First, kernel compression is only possible when the kernel matrices are separable, and in recent years, there has been an increasing interest in NMR sequences with non-separable kernels. Second, in three or more dimensions, the singular value decomposition is not unique; therefore kernel compression is not well-defined for higher dimensions. Without kernel compression, the Kronecker product yields matrices that require large amounts of memory, making the inversion intractable for personal computers. Finally, incorporating arbitrary regularization terms is not possible using the Lawson-Hanson (LH) or the Butler-Reeds-Dawson (BRD) algorithms. We develop a minimization-based inversion method that circumvents the above problems by using multilinear forms to perform multidimensional NMR inversion without using kernel compression or Kronecker products. The new method is memory efficient, requiring less than 0.1% of the memory required by the LH or BRD methods. It can also be extended to arbitrary dimensions and adapted to include non-separable kernels, linear constraints, and arbitrary regularization terms. Additionally, it is easy to implement because only a cost function and its first derivative are required to perform the inversion. PMID:27209370

  11. Multidimensional NMR inversion without Kronecker products: Multilinear inversion

    NASA Astrophysics Data System (ADS)

    Medellín, David; Ravi, Vivek R.; Torres-Verdín, Carlos

    2016-08-01

    Multidimensional NMR inversion using Kronecker products poses several challenges. First, kernel compression is only possible when the kernel matrices are separable, and in recent years, there has been an increasing interest in NMR sequences with non-separable kernels. Second, in three or more dimensions, the singular value decomposition is not unique; therefore kernel compression is not well-defined for higher dimensions. Without kernel compression, the Kronecker product yields matrices that require large amounts of memory, making the inversion intractable for personal computers. Finally, incorporating arbitrary regularization terms is not possible using the Lawson-Hanson (LH) or the Butler-Reeds-Dawson (BRD) algorithms. We develop a minimization-based inversion method that circumvents the above problems by using multilinear forms to perform multidimensional NMR inversion without using kernel compression or Kronecker products. The new method is memory efficient, requiring less than 0.1% of the memory required by the LH or BRD methods. It can also be extended to arbitrary dimensions and adapted to include non-separable kernels, linear constraints, and arbitrary regularization terms. Additionally, it is easy to implement because only a cost function and its first derivative are required to perform the inversion.

  12. GNSS Precise Kinematic Positioning for Multiple Kinematic Stations Based on A Priori Distance Constraints

    PubMed Central

    He, Kaifei; Xu, Tianhe; Förste, Christoph; Petrovic, Svetozar; Barthelmes, Franz; Jiang, Nan; Flechtner, Frank

    2016-01-01

    When applying the Global Navigation Satellite System (GNSS) for precise kinematic positioning in airborne and shipborne gravimetry, multiple GNSS receiving equipment is often fixed mounted on the kinematic platform carrying the gravimetry instrumentation. Thus, the distances among these GNSS antennas are known and invariant. This information can be used to improve the accuracy and reliability of the state estimates. For this purpose, the known distances between the antennas are applied as a priori constraints within the state parameters adjustment. These constraints are introduced in such a way that their accuracy is taken into account. To test this approach, GNSS data of a Baltic Sea shipborne gravimetric campaign have been used. The results of our study show that an application of distance constraints improves the accuracy of the GNSS kinematic positioning, for example, by about 4 mm for the radial component. PMID:27043580

  13. GNSS Precise Kinematic Positioning for Multiple Kinematic Stations Based on A Priori Distance Constraints.

    PubMed

    He, Kaifei; Xu, Tianhe; Förste, Christoph; Petrovic, Svetozar; Barthelmes, Franz; Jiang, Nan; Flechtner, Frank

    2016-04-01

    When applying the Global Navigation Satellite System (GNSS) for precise kinematic positioning in airborne and shipborne gravimetry, multiple GNSS receiving equipment is often fixed mounted on the kinematic platform carrying the gravimetry instrumentation. Thus, the distances among these GNSS antennas are known and invariant. This information can be used to improve the accuracy and reliability of the state estimates. For this purpose, the known distances between the antennas are applied as a priori constraints within the state parameters adjustment. These constraints are introduced in such a way that their accuracy is taken into account. To test this approach, GNSS data of a Baltic Sea shipborne gravimetric campaign have been used. The results of our study show that an application of distance constraints improves the accuracy of the GNSS kinematic positioning, for example, by about 4 mm for the radial component.

  14. GNSS Precise Kinematic Positioning for Multiple Kinematic Stations Based on A Priori Distance Constraints.

    PubMed

    He, Kaifei; Xu, Tianhe; Förste, Christoph; Petrovic, Svetozar; Barthelmes, Franz; Jiang, Nan; Flechtner, Frank

    2016-01-01

    When applying the Global Navigation Satellite System (GNSS) for precise kinematic positioning in airborne and shipborne gravimetry, multiple GNSS receiving equipment is often fixed mounted on the kinematic platform carrying the gravimetry instrumentation. Thus, the distances among these GNSS antennas are known and invariant. This information can be used to improve the accuracy and reliability of the state estimates. For this purpose, the known distances between the antennas are applied as a priori constraints within the state parameters adjustment. These constraints are introduced in such a way that their accuracy is taken into account. To test this approach, GNSS data of a Baltic Sea shipborne gravimetric campaign have been used. The results of our study show that an application of distance constraints improves the accuracy of the GNSS kinematic positioning, for example, by about 4 mm for the radial component. PMID:27043580

  15. How realistic are flat-ramp-flat fault kinematic models? Comparing mechanical and kinematic models

    NASA Astrophysics Data System (ADS)

    Cruz, L.; Nevitt, J. M.; Hilley, G. E.; Seixas, G.

    2015-12-01

    Rock within the upper crust appears to deform according to elasto-plastic constitutive rules, but structural geologists often employ kinematic descriptions that prescribe particle motions irrespective of these physical properties. In this contribution, we examine the range of constitutive properties that are approximately implied by kinematic models by comparing predicted deformations between mechanical and kinematic models for identical fault geometric configurations. Specifically, we use the ABAQUS finite-element package to model a fault-bend-fold geometry using an elasto-plastic constitutive rule (the elastic component is linear and the plastic failure occurs according to a Mohr-Coulomb failure criterion). We varied physical properties in the mechanical model (i.e., Young's modulus, Poisson ratio, cohesion yield strength, internal friction angle, sliding friction angle) to determine the impact of each on the observed deformations, which were then compared to predictions of kinematic models parameterized with identical geometries. We found that a limited sub-set of physical properties were required to produce deformations that were similar to those predicted by the kinematic models. Specifically, mechanical models with low cohesion are required to allow the kink at the bottom of the flat-ramp geometry to remain stationary over time. Additionally, deformations produced by steep ramp geometries (30 degrees) are difficult to reconcile between the two types of models, while lower slope gradients better conform to the geometric assumptions. These physical properties may fall within the range of those observed in laboratory experiments, suggesting that particle motions predicted by kinematic models may provide an approximate representation of those produced by a physically consistent model under some circumstances.

  16. Canopy Components Temperature Retrieval through Bayesian inversion of Directional measurements

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

  17. Improved hydrogeophysical characterization and monitoring through parallel modeling and inversion of time-domain resistivity and induced-polarization data

    SciTech Connect

    Timothy C. Johnson; Roeof J. Versteeg; Andy Ward; Frederick D. Day-Lewis; Andre Revil

    2010-09-01

    Electrical geophysical methods have found wide use in the growing discipline of hydrogeophysics, both for characterizing the electrical properties of the subsurface, and for monitoring subsurface processes in terms of the spatiotemporal changes in subsurface conductivity, chargeability, and source currents they govern. Current multichannel and multielectrode data collections systems are able to collect large amounts of data in relatively short periods of time. However, practitioners are often unable to fully utilize these large data sets and the information they contain due to the processing limitations of standard desktop computers. This limitation can be addressed by utilizing the storage and processing capabilities of high-performance parallel computing environments. We present a parallel distributed-memory forward and inverse modeling algorithm for analyzing resistivity and time-domain induced polarization data. The primary components of the parallel computations include distributed computation of the pole solutions in forward mode, distributed storage and computation of the Jacobian matrix in inverse mode, and parallel execution of the inverse equation solver. We demonstrate the corresponding parallel code for three efforts: (1) resistivity characterization of the Hanford 300 Area Integrated Field Research Challenge site in Hanford, WA; (2) resistivity characterization of a volcanic island in the southern Tyrrhenian Sea in Italy; and (3) resistivity and IP monitoring of biostimulation at a superfund site in Brandywine, MD. Inverse analysis of each of these data sets would be limited (or impossible) in a standard serial computing environment which underscores the need for high-performance computing to fully utilize the potential of electrical geophysical methods in hydrogeophysical applications.

  18. Uncertainty Propagation in Calibration of Parallel Kinematic Machines

    SciTech Connect

    JOKIEL JR.,BERNHARD; ZIERGERT,JOHN C.

    1999-11-02

    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.

  19. A Novel Algorithm for the Generation of Distinct Kinematic Chain

    NASA Astrophysics Data System (ADS)

    Medapati, Sreenivasa Reddy; Kuchibhotla, Mallikarjuna Rao; Annambhotla, Balaji Srinivasa Rao

    2016-07-01

    Generation of distinct kinematic chains is an important topic in the design of mechanisms for various industrial applications i.e., robotic manipulator, tractor, crane etc. Many researchers have intently focused on this area and explained various processes of generating distinct kinematic chains which are laborious and complex. It is desirable to enumerate the kinematic chains systematically to know the inherent characteristics of a chain related to its structure so that all the distinct chains can be analyzed in depth, prior to the selection of a chain for a purpose. This paper proposes a novel and simple method with set of rules defined to eliminate isomorphic kinematic chains generating distinct kinematic chains. Also, this method simplifies the process of generating distinct kinematic chains even at higher levels i.e., 10-link, 11-link with single and multiple degree of freedom.

  20. A Kinematical Approach to Dark Energy Studies

    SciTech Connect

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

    2006-06-06

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

  1. The Kinematics of Dwarf Carbon Stars

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  2. Kinematics of transition during human accelerated sprinting

    PubMed Central

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

    2014-01-01

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

  3. Kinematic Rupture Process Of Karakocan-Elazig Earthquake, Eastern Turkey

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  4. Kinematics and Fluid Dynamics of Jellyfish Maneuvering

    NASA Astrophysics Data System (ADS)

    Miller, Laura; Hoover, Alex

    2014-11-01

    Jellyfish propel themselves through the water through periodic contractions of their elastic bells. Some jellyfish, such as the moon jellyfish Aurelia aurita and the upside down jellyfish Cassiopea xamachana, can perform turns via asymmetric contractions of the bell. The fluid dynamics of jellyfish forward propulsion and turning is explored here by analyzing the contraction kinematics of several species and using flow visualization to quantify the resulting flow fields. The asymmetric contraction and structure of the jellyfish generates asymmetries in the starting and stopping vortices. This creates a diagonal jet and a net torque acting on the jellyfish. Results are compared to immersed boundary simulations

  5. Quantum simulation of noncausal kinematic transformations.

    PubMed

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

    2013-08-30

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

  6. Kinematic Measurements from YouTube Videos

    NASA Astrophysics Data System (ADS)

    Ruiz, Michael J.

    2009-04-01

    Video analysis of motion has been in use now for some time.1-3 However, some teachers may not have video equipment or may be looking for innovative ways to engage students with interesting applications at no cost. The recent advent of YouTube offers opportunities for students to measure kinematic properties of real-life events using their computers. This paper provides examples such as measuring the average speed of a winning horse at the Kentucky Derby, plotting speed versus time from watching the speedometer of a high-performance bike, and determining acceleration for circular motion of amusement park rides.

  7. Kinematic Dynamo In Turbulent Circumstellar Disks

    NASA Technical Reports Server (NTRS)

    Stepinski, T.

    1993-01-01

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

  8. Mapping Dark Matter Halos with Stellar Kinematics

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

  9. Quantum simulation of noncausal kinematic transformations.

    PubMed

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

    2013-08-30

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

  10. Automobile Collisions, Kinematics and Related Injury Patterns

    PubMed Central

    Siegel, A. W.

    1972-01-01

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

  11. Stability of rapid finite-fault inversion for the 2014 Mw6.1 South Napa earthquake

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Wang, Rongjiang; Chen, Yun-Tai

    2015-12-01

    Local seismograms are useful for rapidly reconstructing kinematic finite-fault sources, but the results often depend not only on the data coverage but also on uncertainties of parameters (e.g., hypocentral location and fault geometry) used as a priori information during the inversion. An automatic scheme was applied to offline tests for the 2014 South Napa earthquake. In the case of retrospective full-waveform inversions, a network with station spacing of 10 km within the epicentral distance of 30 km is able to provide adequate stable key source parameters if the preestimated hypocenter and fault orientation are accurate of ±5 km and ±15°, respectively. In simulated real-time inversions, the magnitude reaches Mw6.0 at 13 s, and the slip distribution matches that from the retrospective inversion at about 22-28 s after the origin time of the earthquake. These results are meaningful for estimating the lead time of a catastrophic seismic event.

  12. Thermoelectric properties of inverse opals

    NASA Astrophysics Data System (ADS)

    Mahan, G. D.; Poilvert, N.; Crespi, V. H.

    2016-02-01

    Rayleigh's method [Philos. Mag. Ser. 5 34, 481 (1892)] is used to solve for the classical thermoelectric equations in inverse opals. His theory predicts that in an inverse opal, with periodic holes, the Seebeck coefficient and the figure of merit are identical to that of the bulk material. We also provide a major revision to Rayleigh's method, in using the electrochemical potential as an important variable, instead of the electrostatic potential. We also show that in some cases, the thermal boundary resistance is important in the effective thermal conductivity.

  13. Darwin's "strange inversion of reasoning".

    PubMed

    Dennett, Daniel

    2009-06-16

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

  14. Population inversion by chirped pulses

    SciTech Connect

    Lu Tianshi

    2011-09-15

    In this paper, we analyze the condition for complete population inversion by a chirped pulse over a finite duration. The nonadiabatic transition probability is mapped in the two-dimensional parameter space of coupling strength and detuning amplitude. Asymptotic forms of the probability are derived by the interference of nonadiabatic transitions for sinusoidal and triangular pulses. The qualitative difference between the maps for the two types of pulses is accounted for. The map is used for the design of stable inversion pulses under specific accuracy thresholds.

  15. Multiphase inverse modeling: An Overview

    SciTech Connect

    Finsterle, S.

    1998-03-01

    Inverse modeling is a technique to derive model-related parameters from a variety of observations made on hydrogeologic systems, from small-scale laboratory experiments to field tests to long-term geothermal reservoir responses. If properly chosen, these observations contain information about the system behavior that is relevant to the performance of a geothermal field. Estimating model-related parameters and reducing their uncertainty is an important step in model development, because errors in the parameters constitute a major source of prediction errors. This paper contains an overview of inverse modeling applications using the ITOUGH2 code, demonstrating the possibilities and limitations of a formalized approach to the parameter estimation problem.

  16. Geometric deviation modeling by kinematic matrix based on Lagrangian coordinate

    NASA Astrophysics Data System (ADS)

    Liu, Weidong; Hu, Yueming; Liu, Yu; Dai, Wanyi

    2015-09-01

    Typical representation of dimension and geometric accuracy is limited to the self-representation of dimension and geometric deviation based on geometry variation thinking, yet the interactivity affection of geometric variation and gesture variation of multi-rigid body is not included. In this paper, a kinematic matrix model based on Lagrangian coordinate is introduced, with the purpose of unified model for geometric variation and gesture variation and their interactive and integrated analysis. Kinematic model with joint, local base and movable base is built. The ideal feature of functional geometry is treated as the base body; the fitting feature of functional geometry is treated as the adjacent movable body; the local base of the kinematic model is fixed onto the ideal geometry, and the movable base of the kinematic model is fixed onto the fitting geometry. Furthermore, the geometric deviation is treated as relative location or rotation variation between the movable base and the local base, and it's expressed by the Lagrangian coordinate. Moreover, kinematic matrix based on Lagrangian coordinate for different types of geometry tolerance zones is constructed, and total freedom for each kinematic model is discussed. Finally, the Lagrangian coordinate library, kinematic matrix library for geometric deviation modeling is illustrated, and an example of block and piston fits is introduced. Dimension and geometric tolerances of the shaft and hole fitting feature are constructed by kinematic matrix and Lagrangian coordinate, and the results indicate that the proposed kinematic matrix is capable and robust in dimension and geometric tolerances modeling.

  17. Reliability of lower leg proximal end and forefoot kinematics during different paces of barefoot racewalking on a treadmill using a motion recorder (MVP-RF8-BC)

    PubMed Central

    Wang, Hongzhao; Huo, Ming; An, Xiangde; Li, Yong; Onoda, Ko; Li, Desheng; Huang, Qiuchen; Maruyama, Hitoshi

    2016-01-01

    [Purpose] This study was performed to investigate the changes in lower leg proximal end and forefoot kinematics, and reliability of measurement during different paces of barefoot racewalking on treadmill. [Subjects] Eleven junior racewalking men participated in this study. [Methods] To identify changes in lower leg proximal end and forefoot kinematics, during different paces of barefoot racewalking on a treadmill, a wireless motion recorder (MVP-RF8-BC) was used. Interclass correlation coefficients (ICC 1, 2) were used to estimate reliability. [Results] There were significant differences in the lower leg proximal end and forefoot maximum medial/lateral rotations at a pace of 9 km/h compared with those at a pace of 5 km/h pace. The intra-examiner reliability estimates ranged from 0.82 and 0.89 to 0.87 and 0.93 for lower leg proximal end inversion/eversion rotation and medial/lateral rotation, and from 0.92 and 0.84 to 0.93 and 0.91 for forefoot inversion/eversion rotation and medial/lateral rotation. [Conclusion] We conclude that the lower leg proximal end and forefoot kinematics of barefoot racewalking on a treadmill are influenced by different paces and that assessment of lower leg proximal end and forefoot kinematics by means of the wireless motion recorder (MVP-RF8-BC) is adequately reliable. This information may be useful for determining exercise prescriptions. PMID:27190445

  18. APOGEE Kinematics. I. Overview of the Kinematics of the Galactic Bulge as Mapped By APOGEE

    NASA Astrophysics Data System (ADS)

    Ness, M.; Zasowski, G.; Johnson, J. A.; Athanassoula, E.; Majewski, S. R.; García Pérez, A. E.; Bird, J.; Nidever, D.; Schneider, Donald P.; Sobeck, J.; Frinchaboy, P.; Pan, Kaike; Bizyaev, Dmitry; Oravetz, Daniel; Simmons, Audrey

    2016-03-01

    We present the stellar kinematics across the Galactic bulge and into the disk at positive longitudes from the SDSS-III APOGEE spectroscopic survey of the Milky Way. APOGEE includes extensive coverage of the stellar populations of the bulge along the midplane and near-plane regions. From these data, we have produced kinematic maps of 10,000 stars across longitudes of 0° < l < 65°, and primarily across latitudes of | b| < 5° in the bulge region. The APOGEE data reveal that the bulge is cylindrically rotating across all latitudes and is kinematically hottest at the very center of the bulge, with the smallest gradients in both kinematic and chemical space inside the innermost region (| l,b| ) < (5°, 5°). The results from APOGEE show good agreement with data from other surveys at higher latitudes and a remarkable similarity to the rotation and dispersion maps of barred galaxies viewed edge-on. The thin bar that is reported to be present in the inner disk within a narrow latitude range of | b| < 2° appears to have a corresponding signature in [{Fe}/{{H}}] and [α /{Fe}]. Stars with [{Fe}/{{H}}] > -0.5 have dispersion and rotation profiles that are similar to that of N-body models of boxy/peanut bulges. There is a smooth kinematic transition from the thin bar and boxy bulge (l,| b| ) < (15°, 12°) out to the disk for stars with [{Fe}/{{H}}] > -1.0, and the chemodynamics across (l, b) suggests that the stars in the inner Galaxy with [{Fe}/{{H}}] > -1.0 originate in the disk.

  19. Kinematic GPS Profiles to monitor surface deformation

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    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.

  20. Kinematics and Aerodynamics of Backward Flying Dragonflies

    NASA Astrophysics Data System (ADS)

    Bode-Oke, Ayodeji; Zeyghami, Samane; Dong, Haibo

    2015-11-01

    Highly maneuverable insects such as dragonflies have a wide range of flight capabilities; precise hovering, fast body reorientations, sideways flight and backward takeoff are only a few to mention. In this research, we closely examined the kinematics as well as aerodynamics of backward takeoff in dragonflies and compared them to those of forward takeoff. High speed videography and accurate 3D surface reconstruction techniques were employed to extract details of the wing and body motions as well as deformations during both flight modes. While the velocities of both forward and backward flights were similar, the body orientation as well as the wing kinematics showed large differences. Our results indicate that by tilting the stroke plane angle of the wings as well as changing the orientation of the body relative to the flight path, dragonflies control the direction of the flight like a helicopter. In addition, our detailed analysis of the flow in these flights shows important differences in the wake capture phenomena among these flight modes. This work is supported by NSF CBET-1313217.

  1. THE KINEMATICS OF PRIMATE MIDFOOT FLEXIBILITY

    PubMed Central

    Greiner, Thomas M.; Ball, Kevin A.

    2015-01-01

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

  2. The Kinematics of Turbulent Boundary Layer Structure

    NASA Technical Reports Server (NTRS)

    Robinson, Stephen Kern

    1991-01-01

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

  3. Nuclear Rings in Galaxies - A Kinematic Perspective

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    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.

  4. Flapping flight: effect of asymmetric kinematics

    NASA Astrophysics Data System (ADS)

    Pande, Nakul; Krithivasan, Siddharth; K. R., Sreenivas

    2014-11-01

    Flapping flight has received considerable attention in the past with its relevance in the design of micro-air vehicles. In this regard, asymmetric flapping of wings offers simple kinematics. Nevertheless, it leads to symmetry-breaking in the flow field and generation of sustained lift. It has been observed previously with flow visualization experiments and Discrete Vortex Method (DVM) simulations that if the down-stroke time period is lesser than the up-stroke time, there is a net downward momentum imparted to the fluid. This is seen as a switching the flow field from a four-jet (symmetric) to a two-jet (asymmetric) configuration when the stroke-time ratio is progressively varied. This symmetry breaking has been studied experimentally using Particle Image Velocimetry (PIV) across a range of Reynolds Numbers and asymmetry ratios. Results are also corroborated with results from 3-D numerical simulations. Study helps in shedding light on the effectiveness of asymmetric kinematics as a lift generation mechanism.

  5. Feeding kinematics of phyllomedusine tree frogs.

    PubMed

    Gray, L A; Nishikawa, K C

    1995-02-01

    Previous studies have demonstrated that the phyllomedusine hylids possess highly protrusible tongues, a derived characteristic within the family Hylidae. In the present study, the kinematics of the feeding behavior of a phyllomedusine species, Pachymedusa dacnicolor, was analyzed using high-speed video (180 frames s-1). Its behavior was compared with that of Hyla cinerea, a species with a weakly protrusible tongue. P. dacnicolor exhibits a faster rate of tongue protraction, a longer gape cycle and more variable feeding kinematics than H. cinerea. In addition, the tongue is used in a unique 'fly-swatter' fashion, to pin the prey to the substratum as the frog completes the lunge. The rapid tongue protraction, extended gape cycle and fly-swatter action may have evolved in response to a diet of large, rapidly moving insects. In addition, several duration variables of the feeding cycle were greater for misses than for captures and drops, which suggests that sensory feedback rather than biomechanics controls gape cycle duration.

  6. Kinematics of unconstrained tactile texture exploration.

    PubMed

    Callier, Thierri; Saal, Hannes P; Davis-Berg, Elizabeth C; Bensmaia, Sliman J

    2015-04-01

    A hallmark of tactile texture exploration is that it involves movement between skin and surface. When we scan a surface, small texture-specific vibrations are produced in the skin, and specialized cutaneous mechanoreceptors convert these vibrations into highly repeatable, precise, and informative temporal spiking patterns in tactile afferents. Both texture-elicited vibrations and afferent responses are highly dependent on exploratory kinematics, however; indeed, these dilate or contract systematically with decreases or increases in scanning speed, respectively. These profound changes in the peripheral response that accompany changes in scanning speed and other parameters of texture scanning raise the question as to whether exploratory behaviors change depending on what surface is explored or what information is sought about that surface. To address this question, we measure and analyze the kinematics as subjects explore textured surfaces to evaluate different types of texture information, namely the textures' roughness, hardness, and slipperiness. We find that the exploratory movements are dependent both on the perceptual task, as has been previously shown, but also on the texture that is scanned. We discuss the implications of our findings regarding the neural coding and perception of texture. PMID:25744883

  7. Gait kinematic analysis evaluates hindlimb revascularization.

    PubMed

    Ríos, Amelia; Delgado, Alexandra; Escalante, Bruno; Santana, Jesús

    2011-01-01

    Peripheral arterial occlusive disease is described as vascular disorders associated with ischemia and may be the result of an obstructive vascular process or a lost revascularization response. We have shown that gait locomotion analysis by video filming represents an integrative model for the evaluation of mechanisms involved in the process of ischemia-induced revascularization. However, analysis by this method can be subjective and perception errors may be occurring. We present the optimization of a quantifiable, noninvasive, reproducible method that analyzes ankle kinematics in rats using a two-dimensional digital video system. Gait dynamics were filmed in hindlimb ischemic rats with a high speed digital video camera. Images were collected and analyzed at 125 frames per second. An algorithm using interactive data language (IDL) was devised to assess different parameters. In ischemic rats, stride time and knee joint angle remained altered 10 days post-surgery compared with sham animals. Gait kinematics were outlined in a highly reliable way by this computational analysis and corroborated the notion of hindlimb movement recovery associated with the revascularization process.

  8. Friction Stir Welding at MSFC: Kinematics

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.

    2001-01-01

    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.

  9. Inversions. Popular Lectures in Mathematics.

    ERIC Educational Resources Information Center

    Bakel'man, I. Ya

    Inversions are transformations of geometric figures, under which straight lines may be mapped to circles, and conversely. The use of such mapping allows development of a unified method of solution for many of the problems of elementary geometry, especially those concerning constructions and "pencils" of curves. This book discusses the inversion…

  10. Action Understanding as Inverse Planning

    ERIC Educational Resources Information Center

    Baker, Chris L.; Saxe, Rebecca; Tenenbaum, Joshua B.

    2009-01-01

    Humans are adept at inferring the mental states underlying other agents' actions, such as goals, beliefs, desires, emotions and other thoughts. We propose a computational framework based on Bayesian inverse planning for modeling human action understanding. The framework represents an intuitive theory of intentional agents' behavior based on the…

  11. Applications of inverse pattern projection

    NASA Astrophysics Data System (ADS)

    Li, Wansong; Bothe, Thorsten; Kalms, Michael K.; von Kopylow, Christoph; Jueptner, Werner P. O.

    2003-05-01

    Fast and robust 3D quality control as well as fast deformation measurement is of particular importance for industrial inspection. Additionally a direct response about measured properties is desired. Therefore, robust optical techniques are needed which use as few images as possible for measurement and visualize results in an efficient way. One promising technique for this aim is the inverse pattern projection which has the following advantages: The technique codes the information of a preceding measurement into the projected inverse pattern. Thus, it is possible to do differential measurements using only one camera frame for each state. Additionally, the results are optimized straight fringes for sampling which are independent of the object curvature. The hardware needs are low as just a programmable projector and a standard camera are necessary. The basic idea of inverse pattern projection, necessary algorithms and found optimizations are demonstrated, roughly. Evaluation techniques were found to preserve a high quality phase measurement under imperfect conditions. The different application fields can be sorted out by the type of pattern used for inverse projection. We select two main topics for presentation. One is the incremental (one image per state) deformation measurement which is a promising technique for high speed deformation measurements. A video series of a wavering flag with projected inverse pattern was evaluated to show the complete deformation series. The other application is the optical feature marking (augmented reality) that allows to map any measured result directly onto the object under investigation. Any properties can be visualized directly on the object"s surface which makes inspections easier than with use of a separated indicating device. The general ability to straighten any kind of information on 3D surfaces is shown while preserving an exact mapping of camera image and object parts. In many cases this supersedes an additional monitor to

  12. Derivation and reliability of kinematic measures of sperm motion.

    PubMed

    Davis, R O; Siemers, R J

    1995-01-01

    Studies of sperm movement are relevant in the diagnosis of sperm function and in investigations of cellular biology. Such studies have been traditionally performed by analysing the kinematics of the flagellum or the head. Analysis of the flagellum can provide insights into the cell biological mechanisms responsible for the control of movement. However, the mathematical correspondence between head kinematics and flagellum kinematics is not unique. Therefore, it is not possible to use head kinematics to obtain detailed insights into cell mechanisms or physiology. The accuracy and precision of kinematic measurements are limited by a number of technical and biological factors. Therefore, the interpretation of kinematic data is dependent on a thorough understanding of the assumptions and conditions underlying the analysis. Evaluation of the reliability of kinematic measurements has suffered because no absolute standard for measurement has existed. The development and application of a new standard based on images which were simulated using the equations of motion is described. Because the kinematics of these images are known prior to empirical measurement, the performance of different methods can be determined absolutely. Some kinematic measures are unreliable because they are inappropriate analogues for engineering concepts. The development and use of appropriate engineering measures for the frequency and amplitude of sperm motion is also described. Some types of sperm motion cannot be analysed using kinematic measures (e.g. hyperactivated movement). The concept of the fractal dimension as a more accurate measurement for such motions is introduced. It is concluded that kinematic measurements of sperm motion can provide valuable information about cell biological mechanisms (in the case of the flagellum) and about general membrane and axoneme function (in the case of the head) when the measurements are made under the appropriate conditions, when standard techniques are

  13. Inverse dynamics of a 3 degree of freedom spatial flexible manipulator

    NASA Technical Reports Server (NTRS)

    Bayo, Eduardo; Serna, M.

    1989-01-01

    A technique is presented for solving the inverse dynamics and kinematics of 3 degree of freedom spatial flexible manipulator. The proposed method finds the joint torques necessary to produce a specified end effector motion. Since the inverse dynamic problem in elastic manipulators is closely coupled to the inverse kinematic problem, the solution of the first also renders the displacements and rotations at any point of the manipulator, including the joints. Furthermore the formulation is complete in the sense that it includes all the nonlinear terms due to the large rotation of the links. The Timoshenko beam theory is used to model the elastic characteristics, and the resulting equations of motion are discretized using the finite element method. An iterative solution scheme is proposed that relies on local linearization of the problem. The solution of each linearization is carried out in the frequency domain. The performance and capabilities of this technique are tested through simulation analysis. Results show the potential use of this method for the smooth motion control of space telerobots.

  14. Deployable antenna kinematics using tensegrity structure design

    NASA Astrophysics Data System (ADS)

    Knight, Byron Franklin

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

  15. A School Experiment in Kinematics: Shooting from a Ballistic Cart

    ERIC Educational Resources Information Center

    Kranjc, T.; Razpet, N.

    2011-01-01

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

  16. Lingual Kinematics during Rapid Syllable Repetition in Parkinson's Disease

    ERIC Educational Resources Information Center

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

    2012-01-01

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

  17. Zero-Inertial Recession for a Kinematic Wave Model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Kinematic-wave models of surface irrigation assume a fixed relationship between depth and discharge (typically, normal depth). When surface irrigation inflow is cut off, the calculated upstream flow depth goes to zero, since the discharge is zero. For short time steps, use of the Kinematic Wave mode...

  18. The impact of tibial torsion measurements on gait analysis kinematics

    PubMed Central

    Lucareli, Paulo Roberto Garcia; Santos, Nadia Maria; Godoy, Wagner De; Bernal, Milena Moreira Barreto; Paes, Ângela Tavares; Ramalho, Amancio

    2014-01-01

    Objective: To measure and compare tibial torsion values as assessed by goniometry and three-dimensional kinematics. In addition, the impact of each one of these measurements on kinematic and kinetic results for normal gait was determined. Methods: Twenty-three healthy and fully ambulatory patients were assessed, 11 women and 12 men, from 20 to 40 years old. Data were collected at a laboratory for the three-dimensional analysis of movement with 10 cameras and two force plates. Tibial torsion measurements were obtained using goniometry and three-dimensional kinematics based on the Plug-in Gait model. Afterwards, both procedures were compared, and the impact of each result was assessed on the kinematic and kinetic modeling of the knee and ankle. Results: Pearson's linear correlation coefficient (r=0,504) showed a moderate correlation between the three-dimensional kinematics and goniometry, and between the changes in the measurements. Regarding the processed kinematic and kinetic results for every torsion position, no significant differences were noticed among any of the studied variables (p>0.05). Conclusion: Although statistical correlation among tibial torsion angles by goniometry and three-dimensional kinematic were moderate, kinematic and kinetic analysis of the joints did not reveal any significant changes. Level of Evidence I, Diagnostic Studies - Investigating a Diagnostic Test. PMID:25328438

  19. Kinematic Signatures of Telic and Atelic Events in ASL Predicates

    ERIC Educational Resources Information Center

    Malaia, Evie; Wilbur, Ronnie B.

    2012-01-01

    This article presents an experimental investigation of kinematics of verb sign production in American Sign Language (ASL) using motion capture data. The results confirm that event structure differences in the meaning of the verbs are reflected in the kinematic formation: for example, in the telic verbs (throw, hit), the end-point of the event is…

  20. Medial compressible forefoot sole elements reduce ankle inversion in lateral SSC jumps.

    PubMed

    Fleischmann, Jana; Mornieux, Guillaume; Gehring, Dominic; Gollhofer, Albert

    2013-06-01

    Sideward movements are associated with high incidences of lateral ankle sprains. Special shoe constructions might be able to reduce these injuries during lateral movements. The purpose of this study was to investigate whether medial compressible forefoot sole elements can reduce ankle inversion in a reactive lateral movement, and to evaluate those elements' influence on neuromuscular and mechanical adjustments in lower extremities. Foot placement and frontal plane ankle joint kinematics and kinetics were analyzed by 3-dimensional motion analysis. Electromyographic data of triceps surae, peroneus longus, and tibialis anterior were collected. This modified shoe reduced ankle inversion in comparison with a shoe with a standard sole construction. No differences in ankle inversion moments were found. With the modified shoe, foot placement occurred more internally rotated, and muscle activity of the lateral shank muscles was reduced. Hence, lateral ankle joint stability during reactive sideward movements can be improved by these compressible elements, and therefore lower lateral shank muscle activity is required. As those elements limit inversion, the strategy to control inversion angles via a high external foot rotation does not need to be used.

  1. Numerical analysis of kinematic soil-pile interaction

    SciTech Connect

    Castelli, Francesco; Maugeri, Michele; Mylonakis, George

    2008-07-08

    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.

  2. Relativistic kinematics for motion faster than light

    NASA Technical Reports Server (NTRS)

    Jones, R. T.

    1982-01-01

    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.

  3. Unraveling L_{n,k}: Grassmannian Kinematics

    SciTech Connect

    Kaplan, Jared; /SLAC

    2010-02-15

    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.

  4. Galaxy simulations: Kinematics and mock observations

    NASA Astrophysics Data System (ADS)

    Moody, Christopher E.

    2013-08-01

    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

  5. Adjustable link for kinematic mounting systems

    DOEpatents

    Hale, Layton C.

    1997-01-01

    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.

  6. Adjustable link for kinematic mounting systems

    DOEpatents

    Hale, L.C.

    1997-07-01

    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.

  7. Kinematics of chiropteran shoulder girdle in flight.

    PubMed

    Panyutina, A A; Kuznetsov, A N; Korzun, L P

    2013-03-01

    New data on the mechanisms of movements of the shoulder girdle and humerus of bats are described; potential mobility is compared to the movements actually used in flight. The study was performed on the basis of morphological and functional analysis of anatomical specimens of 15 species, high speed and high definition filming of two species and X-ray survey of Rousettus aegyptiacus flight. Our observations indicate that any excursions of the shoulder girdle in bats have relatively small input in the wing amplitude. Shoulder girdle movements resemble kinematics of a crank mechanism: clavicle plays the role of crank, and scapula-the role of connecting rod. Previously described osseous "locking mechanisms" in shoulder joint of advanced bats do not affect the movements, actually used in flight. The wing beats in bats are performed predominantly by movements of humerus relative to shoulder girdle, although these movements occupy the caudal-most sector of available shoulder mobility. PMID:23381941

  8. Global and regional kinematics from SLR stations

    NASA Technical Reports Server (NTRS)

    Dunn, Peter J.

    1994-01-01

    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.

  9. Kinematic Solar Dynamo with Spot Deposition

    NASA Astrophysics Data System (ADS)

    Karak, Bidya Binay; Miesch, Mark S.

    2016-05-01

    We have recently developed a kinematic dynamo model by including the observed differential rotation and the meridional flow. This model includes the emergence of sunspots from the deep-seated toroidal field and their subsequent decay at the surface, i.e., the Babcock-Leighton process for the generation of poloidal field.We shall show that this model reproduces most of the basic features of the solar magnetic cycle including the polarity reversals, 11 years periodicity, equatorward migration of sunspots at low latitudes and the poleward migration of the radial field at the surface. This model also produces the observed cycle variations when the fluctuations in the active-region tilt are included. North-south asymmetries of cycles from this model will also be demonstrated.

  10. Galactic kinematics derived from classical cepheids

    NASA Astrophysics Data System (ADS)

    Zhu, Zi

    On the basis of radial velocity and Hipparcos proper motion data, we have analyzed the galactic kinematics of classical Cepheids. Using the 3-D Ogorodnikov-Milne model we have determined the rotational velocity of the Galaxy to be V0 = 240.5 ± 10.2 km/s, on assuming a glactocentric distance of the Sun of R0 = 8.5 kpc. The results clearly indicate a contracting motion in the solar neighbourhood of (∂V θ∂θ)/R = -2.60 ± 1.07 km s -1 kpc -1, along the direction of galactic rotation. Possible reason for this motion is discussed. The solar motion found here is S⊙ = 18.78 ± 0.86 km/s in the direction l⊙ = 54.4° ± 2.9° and b⊙ = +26.6° ± 2.6°.

  11. Uncertainty quantification in kinematic wave models

    SciTech Connect

    Wang, Peng; Tartakovsky, Daniel M.

    2012-10-01

    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.

  12. SPACEBAR: Kinematic design by computer graphics

    NASA Technical Reports Server (NTRS)

    Ricci, R. J.

    1975-01-01

    The interactive graphics computer program SPACEBAR, conceived to reduce the time and complexity associated with the development of kinematic mechanisms on the design board, was described. This program allows the direct design and analysis of mechanisms right at the terminal screen. All input variables, including linkage geometry, stiffness, and applied loading conditions, can be fed into or changed at the terminal and may be displayed in three dimensions. All mechanism configurations can be cycled through their range of travel and viewed in their various geometric positions. Output data includes geometric positioning in orthogonal coordinates of each node point in the mechanism, velocity and acceleration of the node points, and internal loads and displacements of the node points and linkages. All analysis calculations take at most a few seconds to complete. Output data can be viewed at the scope and also printed at the discretion of the user.

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

    NASA Astrophysics Data System (ADS)

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

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

  14. Color-kinematics duality in multi-Regge kinematics and dimensional reduction

    NASA Astrophysics Data System (ADS)

    Johansson, Henrik; Vera, Agustín Sabio; Campillo, Eduardo Serna; Vázquez-Mozo, Miguel Á.

    2013-10-01

    In this note we study the applicability of the color-kinematics duality to the scattering of two distinguishable scalar matter particles with gluon emission in QCD, or graviton emission in Einstein gravity. Previous analysis suggested that direct use of the Bern-Carrasco-Johansson double-copy prescription to matter amplitudes does not reproduce the gravitational amplitude in multi-Regge kinematics. This situation, however, can be avoided by extensions to the gauge theory, while maintaning the same Regge limit. Here we present two examples of these extensions: the introduction of a scalar contact interaction and the relaxation of the distinguishability of the scalars. In both cases new diagrams allow for a full reconstruction of the correct Regge limit on the gravitational side. Both modifications correspond to theories obtained by dimensional reduction from higher-dimensional gauge theories.

  15. Feeding kinematics of juvenile swellsharks, Cephaloscyllium ventriosum

    PubMed

    Ferry-Graham

    1997-01-01

    To investigate how feeding behaviors change with prey size, high-speed video recording was used to examine the kinematics of prey capture and transport in 1-year-old swellsharks Cephaloscyllium ventriosum (Scyliorhinidae: Carchariniformes) feeding on two differently sized prey items. Prey capture in these sharks generally consisted of an initially ram-dominated capture bite, one or more manipulation bites, a holding phase during which the food was held in the teeth of the shark, and then suction-dominated prey transport. During initial capture and transport, most of the water taken in is forced back out of the mouth anteriorly rather than continuing posteriorly out through the gill openings. Dye experiments in which dye-perfused prey items were ingested by the sharks confirm this observation; distinct jets of colored water were video-taped as they were ejected from the mouth. Very late in prey transport, a bolus of water is ejected through the gill slits; however, by this time, the majority of water appears already to have exited the buccal cavity through the mouth. Such patterns were observed for sharks feeding on both small and large prey items. Although a basic pattern of prey capture and transport was regularly repeated among strikes, kinematic patterns during prey capture and transport were variable both within and among individuals, indicating that prey acquisition is not tightly controlled. However, the amount of variability was similar among prey sizes. In addition, there were no detectable changes in behavior due to prey item size. Ram-suction index values confirmed that similar capture modes were being utilized for both prey sizes. PMID:9319118

  16. Cervical kinematics during drinking in developing chickens.

    PubMed

    Heidweiller, J; Van der Leeuw, A H; Zweers, G A

    1992-05-01

    Development of head neck motion patterns is studied in drinking chickens to examine (1) general motion principles, (2) ontogenetic changes in these patterns, and (3) whether pattern changes are due to scaling effects during growth. Behavioral patterns are analyzed by high speed filming, radiography, and calculation of rotation patterns for each joint during all movement patterns. Flexibility and variability are great, but representative kinematic patterns are selected for immersion, upstroke, and tip-up phases. Five principles were found that control cervical motion. Two principles maximize rotation efficiency: the geometric and lever arm principles. Two trajectory compensating principles occur; one controls compensation for overflexion, and the other corrects curved into straight trajectories of head motion. One principle occurs that minimizes rotation force if large forces tend to develop in one joint. This principle results in a characteristic cervical motion pattern ("bike chain" pattern). There are three developmental periods: (1) hatchlings (2) chickens 1 to 4 weeks old (1-4W), and (3) older than 4 weeks. Each period is characterized by different kinematic patterns. In 1-4W chicks, the rotation force is minimized. In older stages, the cervical joints rotate according to geometric and lever arm principles. The totally different motion pattern in hatchlings results from a different behavioral reaction to water and the influence of large centrifugal forces. Transitions in cervical motion patterns are connected to effects of scaling, primarily changes in head and body weights. Changes in motion patterns are not related to changes in anatomical characters such as flexion extremes and relative length of each vertebra since these are similar in all stages.

  17. A Kinematic Study of Finswimming at Surface

    PubMed Central

    Gautier, Jimmy; Baly, Laurent; Zanone, Pier-Giorgio; Watier, Bruno

    2004-01-01

    Finswimming is a sport of speed practiced on the surface or underwater, in which performance is based on whole-body oscillations. The present study investigated the undulatory motion performed by finswimmers at the surface. This study aiming to analyze the influence of the interaction of gender, practice level, and race distance on selected kinematic parameters. Six elite and six novices finswimmers equipped with joints markers (wrist, elbow, shoulder, hip, knee, and ankle) were recorded in the sagittal plane. The position of these anatomical marks was digitized at 50 Hz. An automated motion analysis software yielded velocity, vertical amplitude, frequency, and angular position. Results showed that stroke frequency decreased whereas the mean amplitude of all joints increased with increasing race distance (p < 0.01). Mean joint amplitude for the upper limbs (wrist, elbow and shoulder) was smaller for experts than for novices. Whereas that of the ankle was larger, so that the oscillation amplitude increased from shoulder to ankle. Elite male finswimmers were pitching more acutely than female. Moreover, elite male finswimmers showed a smaller knee bending than novices and than elite females (p < 0.01). This indicated that elite male finswimmers attempt to reduce drag forces thanks to a weak knee bending and a low upper limbs pitch. To sum up, gender, expertise, and race distance affect the performance and its kinematics in terms frontal drag. Expertise in finswimming requires taking advantage of the mechanical constraints pertaining to hydrodynamic constraints in order to optimize performance. Key Points Finswimmers are at one and the same time a propelling and a propelled body. This study investigates the undulatory motion performed by finswimmers at the surface. Elite male finswimmers were pitching more acutely than female swimmers and showed a smaller knee bending than both novices and elite female swimmers. Finswimmers tended to perform a dolphin-like motion

  18. Feeding kinematics of juvenile swellsharks, Cephaloscyllium ventriosum

    PubMed

    Ferry-Graham

    1997-01-01

    To investigate how feeding behaviors change with prey size, high-speed video recording was used to examine the kinematics of prey capture and transport in 1-year-old swellsharks Cephaloscyllium ventriosum (Scyliorhinidae: Carchariniformes) feeding on two differently sized prey items. Prey capture in these sharks generally consisted of an initially ram-dominated capture bite, one or more manipulation bites, a holding phase during which the food was held in the teeth of the shark, and then suction-dominated prey transport. During initial capture and transport, most of the water taken in is forced back out of the mouth anteriorly rather than continuing posteriorly out through the gill openings. Dye experiments in which dye-perfused prey items were ingested by the sharks confirm this observation; distinct jets of colored water were video-taped as they were ejected from the mouth. Very late in prey transport, a bolus of water is ejected through the gill slits; however, by this time, the majority of water appears already to have exited the buccal cavity through the mouth. Such patterns were observed for sharks feeding on both small and large prey items. Although a basic pattern of prey capture and transport was regularly repeated among strikes, kinematic patterns during prey capture and transport were variable both within and among individuals, indicating that prey acquisition is not tightly controlled. However, the amount of variability was similar among prey sizes. In addition, there were no detectable changes in behavior due to prey item size. Ram-suction index values confirmed that similar capture modes were being utilized for both prey sizes.

  19. Ultrahigh-intensity inverse bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Kostyukov, I. Yu.; Rax, J.-M.

    1999-01-01

    We study inverse bremsstrahlung in the ultrahigh intensity relativistic regime. The fully relativistic ultrahigh intensity absorption (emission) coefficient is derived for an arbitrary scattering potential and small-angle scattering. We find that in the Coulomb field case this absorption (emission) coefficient can be calculated as a function of the quiver energy, drift momentum, and impact parameter in two complementary regimes: (i) for remote collisions when the impact parameter is larger than the amplitude of the quiver motion, and (ii) for instantaneous collisions when the scattering time is shorter than the period of the wave. Both circular and linear polarizations are considered, and this study reveals that in this relativistic regime inverse bremsstrahlung absorption can be viewed as a harmonic Compton resonance heating of the laser-driven electron by the virtual photon of the ion Coulomb field. The relativistic modification of Marcuse's effect [Bell Syst. Tech. J. 41, 1557 (1962)] are also discussed, and relations with previous nonrelativistic results are elucidated.

  20. Momentum resolution in inverse photoemission

    SciTech Connect

    Zumbülte, A.; Schmidt, A. B.; Donath, M.

    2015-01-15

    We present a method to determine the electron beam divergence, and thus the momentum resolution, of an inverse-photoemission setup directly from a series of spectra measured on Cu(111). Simulating these spectra with different beam divergences shows a distinct influence of the divergence on the appearance of the Shockley surface state. Upon crossing the Fermi level, its rise in intensity can be directly linked with the beam divergence. A comparison of measurement and simulation enables us to quantify the momentum resolution independent of surface quality, energy resolution, and experimental geometry. With spin resolution, a single spectrum taken around the Fermi momentum of a spin-split surface state, e.g., on Au(111), is sufficient to derive the momentum resolution of an inverse-photoemission setup.

  1. Momentum resolution in inverse photoemission.

    PubMed

    Zumbülte, A; Schmidt, A B; Donath, M

    2015-01-01

    We present a method to determine the electron beam divergence, and thus the momentum resolution, of an inverse-photoemission setup directly from a series of spectra measured on Cu(111). Simulating these spectra with different beam divergences shows a distinct influence of the divergence on the appearance of the Shockley surface state. Upon crossing the Fermi level, its rise in intensity can be directly linked with the beam divergence. A comparison of measurement and simulation enables us to quantify the momentum resolution independent of surface quality, energy resolution, and experimental geometry. With spin resolution, a single spectrum taken around the Fermi momentum of a spin-split surface state, e.g., on Au(111), is sufficient to derive the momentum resolution of an inverse-photoemission setup.

  2. Simplified, inverse, ejector design tool

    NASA Technical Reports Server (NTRS)

    Dechant, Lawrence J.

    1993-01-01

    A simple lumped parameter based inverse design tool has been developed which provides flow path geometry and entrainment estimates subject to operational, acoustic, and design constraints. These constraints are manifested through specification of primary mass flow rate or ejector thrust, fully-mixed exit velocity, and static pressure matching. Fundamentally, integral forms of the conservation equations coupled with the specified design constraints are combined to yield an easily invertible linear system in terms of the flow path cross-sectional areas. Entrainment is computed by back substitution. Initial comparison with experimental and analogous one-dimensional methods show good agreement. Thus, this simple inverse design code provides an analytically based, preliminary design tool with direct application to High Speed Civil Transport (HSCT) design studies.

  3. Inverse psoriasis treated with ustekinumab.

    PubMed

    Campos, Manuel António; Varela, Paulo; Baptista, Armando; Moreira, Ana Isabel

    2016-01-01

    Inverse psoriasis is characterised by the involvement of flexural skin folds. This form of psoriasis has distinct clinical and therapeutic features. This report refers to the case of a 48-year-old Caucasian man who was observed in our department, with a clinically and biopsy proven diagnosis of inverse psoriasis. For 2 years, the patient was treated with different combinations of corticosteroids, vitamin D analogues and methotrexate, with no satisfactory response. Given the lack of a clinical response and comorbidities, latent tuberculosis was excluded, and we started treatment with ustekinumab. We chose this biological agent because the patient was a long-distance truck driver and refused the possibility of autoinjections. The patient underwent three ustekinumab injections, which resulted in significant improvement of pruritus, erythaematous lesions and quality of life. PMID:27222277

  4. Optimal estimation of dynamically consistent kinematics and kinetics for forward dynamic simulation of gait.

    PubMed

    Remy, C David; Thelen, Darryl G

    2009-03-01

    Forward dynamic simulation provides a powerful framework for characterizing internal loads and for predicting changes in movement due to injury, impairment or surgical intervention. However, the computational challenge of generating simulations has greatly limited the use and application of forward dynamic models for simulating human gait. In this study, we introduce an optimal estimation approach to efficiently solve for generalized accelerations that satisfy the overall equations of motion and best agree with measured kinematics and ground reaction forces. The estimated accelerations are numerically integrated to enforce dynamic consistency over time, resulting in a forward dynamic simulation. Numerical optimization is then used to determine a set of initial generalized coordinates and speeds that produce a simulation that is most consistent with the measured motion over a full cycle of gait. The proposed method was evaluated with synthetically created kinematics and force plate data in which both random noise and bias errors were introduced. We also applied the method to experimental gait data collected from five young healthy adults walking at a preferred speed. We show that the proposed residual elimination algorithm (REA) converges to an accurate solution, reduces the detrimental effects of kinematic measurement errors on joint moments, and eliminates the need for residual forces that arise in standard inverse dynamics. The greatest improvements in joint kinetics were observed proximally, with the algorithm reducing joint moment errors due to marker noise by over 20% at the hip and over 50% at the low back. Simulated joint angles were generally within 1 deg of recorded values when REA was used to generate a simulation from experimental gait data. REA can thus be used as a basis for generating accurate simulations of subject-specific gait dynamics.

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

    SciTech Connect

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

    2013-12-15

    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 μm × 11.6 μm 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.

  6. Stochastic inversion by ray continuation

    SciTech Connect

    Haas, A.; Viallix

    1989-05-01

    The conventional tomographic inversion consists in minimizing residuals between measured and modelled traveltimes. The process tends to be unstable and some additional constraints are required to stabilize it. The stochastic formulation generalizes the technique and sets it on firmer theoretical bases. The Stochastic Inversion by Ray Continuation (SIRC) is a probabilistic approach, which takes a priori geological information into account and uses probability distributions to characterize data correlations and errors. It makes it possible to tie uncertainties to the results. The estimated parameters are interval velocities and B-spline coefficients used to represent smoothed interfaces. Ray tracing is done by a continuation technique between source and receives. The ray coordinates are computed from one path to the next by solving a linear system derived from Fermat's principle. The main advantages are fast computations, accurate traveltimes and derivatives. The seismic traces are gathered in CMPs. For a particular CMP, several reflecting elements are characterized by their time gradient measured on the stacked section, and related to a mean emergence direction. The program capabilities are tested on a synthetic example as well as on a field example. The strategy consists in inverting the parameters for one layer, then for the next one down. An inversion step is divided in two parts. First the parameters for the layer concerned are inverted, while the parameters for the upper layers remain fixed. Then all the parameters are reinverted. The velocity-depth section computed by the program together with the corresponding errors can be used directly for the interpretation, as an initial model for depth migration or for the complete inversion program under development.

  7. Pyramidal inversion domain boundaries revisited

    SciTech Connect

    Remmele, T.; Albrecht, M.; Irmscher, K.; Fornari, R.; Strassburg, M.

    2011-10-03

    The structure of pyramidal inversion domain boundaries in GaN:Mg was investigated by aberration corrected transmission electron microscopy. The analysis shows the upper (0001) boundary to consist of a single Mg layer inserted between polarity inverted GaN layers in an abcab stacking. The Mg bound in these defects is at least one order of magnitude lower than the chemical Mg concentration. Temperature dependent Hall effect measurements show that up to 27% of the Mg acceptors is electrically compensated.

  8. Phenomenological description of phase inversion.

    PubMed

    Piela, K; Ooms, G; Sengers, J V

    2009-02-01

    We propose an extended Ginzburg-Landau model for a description of the ambivalence region associated with the phenomenon of phase inversion observed in dispersed water-oil flow through a pipe. In analogy to the classical mean-field theory of phase transitions, it is shown that a good quantitative representation of the ambivalence region is obtained by using the injected phase volume fraction and a friction factor as the appropriate physical parameters.

  9. The relationship between gluteal muscle activation and throwing kinematics in baseball and softball catchers.

    PubMed

    Plummer, Hillary A; Oliver, Gretchen D

    2014-01-01

    The purpose of this study was to determine the relationship between gluteal muscle activation and pelvis and trunk kinematics when catchers throw to second base. Forty-two baseball and softball catchers (14.74 ± 4.07 years; 161.85 ± 15.24 cm; 63.38 ± 19.98 kg) participated in this study. Muscle activity of the bilateral gluteus maximus and medius as well as pelvis and trunk kinematics throughout the throwing motion were analyzed. It was discovered that at foot contact, there were 2 significant inverse relationships between stride leg gluteus maximus activity and pelvis axial rotation (r = -0.31, r2 = 0.10, p = 0.05), and between trunk axial rotation and pelvis lateral flexion (r = -0.34, r2= 0.12, p = 0.03). In addition, at foot contact, a significant positive relationship between the drive leg (throwing arm side) and trunk flexion (r = 0.33, r2 = 0.11, p = 0.04) was present. The results of this study provide evidence of gluteal activation both concentrically and eccentrically, in attempt to control the pelvis and trunk during the throwing motion of catchers. The gluteal muscles play a direct role in maintaining the stability of the pelvis, and catchers should incorporate strengthening of the entire lumbopelvic-hip complex into their training regimen. Incorporating concentric and eccentric gluteal exercises will help to improve musculoskeletal core stability, thereby assisting in upper extremity injury prevention.

  10. Ionized gas kinematics of galaxies in the CALIFA survey. I. Velocity fields, kinematic parameters of the dominant component, and presence of kinematically distinct gaseous systems

    NASA Astrophysics Data System (ADS)

    García-Lorenzo, B.; Márquez, I.; Barrera-Ballesteros, J. K.; Masegosa, J.; Husemann, B.; Falcón-Barroso, J.; Lyubenova, M.; Sánchez, S. F.; Walcher, J.; Mast, D.; García-Benito, R.; Méndez-Abreu, J.; van de Ven, G.; Spekkens, K.; Holmes, L.; Monreal-Ibero, A.; del Olmo, A.; Ziegler, B.; Bland-Hawthorn, J.; Sánchez-Blázquez, P.; Iglesias-Páramo, J.; Aguerri, J. A. L.; Papaderos, P.; Gomes, J. M.; Marino, R. A.; González Delgado, R. M.; Cortijo-Ferrero, C.; López-Sánchez, A. R.; Bekeraitė, S.; Wisotzki, L.; Bomans, D.

    2015-01-01

    Context. Ionized gas kinematics provide important clues to the dynamical structure of galaxies and hold constraints to the processes driving their evolution. Aims: The motivation of this work is to provide an overall characterization of the kinematic behavior of the ionized gas of the galaxies included in the Calar Alto Legacy Integral field Area (CALIFA), offering kinematic clues to potential users of the CALIFA survey for including kinematical criteria in their selection of targets for specific studies. From the first 200 galaxies observed by CALIFA survey in its two configurations, we present the two-dimensional kinematic view of the 177 galaxies satisfaying a gas content/detection threshold. Methods: After removing the stellar contribution, we used the cross-correlation technique to obtain the radial velocity of the dominant gaseous component for each spectrum in the CALIFA data cubes for different emission lines (namely, [O ii] λλ3726,3729, [O iii] λλ4959,5007, Hα+[N ii] λλ6548,6584, and [SII]λλ6716,6730). The main kinematic parameters measured on the plane of the sky were directly derived from the radial velocities with no assumptions on the internal prevailing motions. Evidence of the presence of several gaseous components with different kinematics were detected by using [O iii] λλ4959,5007 emission line profiles. Results: At the velocity resolution of CALIFA, most objects in the sample show regular velocity fields, although the ionized-gas kinematics are rarely consistent with simple coplanar circular motions. Thirty-five percent of the objects present evidence of a displacement between the photometric and kinematic centers larger than the original spaxel radii. Only 17% of the objects in the sample exhibit kinematic lopsidedness when comparing receding and approaching sides of the velocity fields, but most of them are interacting galaxies exhibiting nuclear activity (AGN or LINER). Early-type (E+S0) galaxies in the sample present clear

  11. On the Magic Square and Inverse

    ERIC Educational Resources Information Center

    Elzaidi, S. M.

    2005-01-01

    In this note, we give a method for finding the inverse of a three by three magic square matrix without using the usual methods for finding the inverse of a matrix. Also we give a method for finding the inverse of a three by three magic square matrix whose entries are also matrices. By using these ideas, we can construct large matrices whose…

  12. Recombination rate predicts inversion size in Diptera.

    PubMed

    Cáceres, M; Barbadilla, A; Ruiz, A

    1999-09-01

    Most species of the Drosophila genus and other Diptera are polymorphic for paracentric inversions. A common observation is that successful inversions are of intermediate size. We test here the hypothesis that the selected property is the recombination length of inversions, not their physical length. If so, physical length of successful inversions should be negatively correlated with recombination rate across species. This prediction was tested by a comprehensive statistical analysis of inversion size and recombination map length in 12 Diptera species for which appropriate data are available. We found that (1) there is a wide variation in recombination map length among species; (2) physical length of successful inversions varies greatly among species and is inversely correlated with the species recombination map length; and (3) neither the among-species variation in inversion length nor the correlation are observed in unsuccessful inversions. The clear differences between successful and unsuccessful inversions point to natural selection as the most likely explanation for our results. Presumably the selective advantage of an inversion increases with its length, but so does its detrimental effect on fertility due to double crossovers. Our analysis provides the strongest and most extensive evidence in favor of the notion that the adaptive value of inversions stems from their effect on recombination.

  13. Recombination rate predicts inversion size in Diptera.

    PubMed Central

    Cáceres, M; Barbadilla, A; Ruiz, A

    1999-01-01

    Most species of the Drosophila genus and other Diptera are polymorphic for paracentric inversions. A common observation is that successful inversions are of intermediate size. We test here the hypothesis that the selected property is the recombination length of inversions, not their physical length. If so, physical length of successful inversions should be negatively correlated with recombination rate across species. This prediction was tested by a comprehensive statistical analysis of inversion size and recombination map length in 12 Diptera species for which appropriate data are available. We found that (1) there is a wide variation in recombination map length among species; (2) physical length of successful inversions varies greatly among species and is inversely correlated with the species recombination map length; and (3) neither the among-species variation in inversion length nor the correlation are observed in unsuccessful inversions. The clear differences between successful and unsuccessful inversions point to natural selection as the most likely explanation for our results. Presumably the selective advantage of an inversion increases with its length, but so does its detrimental effect on fertility due to double crossovers. Our analysis provides the strongest and most extensive evidence in favor of the notion that the adaptive value of inversions stems from their effect on recombination. PMID:10471710

  14. Broad-band strong motion simulations coupling k-square kinematic source models with empirical Green's functions: the 2009 L'Aquila earthquake

    NASA Astrophysics Data System (ADS)

    Del Gaudio, Sergio; Causse, Mathieu; Festa, Gaetano

    2015-10-01

    The use of simulated accelerograms may improve the evaluation of the seismic hazard when an accurate modelling of both source and propagation is performed. In this paper, we performed broad-band simulations of the 2009, M 6.3 L'Aquila earthquake, coupling a k-2 kinematic model for the seismic source with empirical Green's functions (EGFs) as propagators. We extracted 10 EGFs candidates from a database of aftershocks satisfying quality criteria based on signal-to-noise ratio, fault proximity, small magnitude, similar focal mechanism and stress drop. For comparison with real observations, we also derived a low-frequency kinematic model, based on inversion of ground displacement as integrated from strong motion data. Kinematic properties of the inverted model (rupture velocity, position of the rupture nucleation, low-frequency slip and roughness degree of slip heterogeneity) were used as constraints in the k-2 model, to test the use of a single specific EGF against the use of the whole set of EGFs. Comparison to real observations based on spectral and peak ground acceleration shows that the use of all available EGFs improves the fit of simulations to real data. Moreover the epistemic variability related to the selection of a specific EGF is significantly larger (two to three times) than recent observations of between event variability, that is the variability associated with the randomness of the rupture process. We finally performed `blind' simulations releasing all the information on source kinematics and only considering the fault geometry and the magnitude of the target event as known features. We computed peak ground acceleration, acceleration Fourier and response spectra. Simulations follow the same trend with distance as real observations. In most cases these latter fall within one sigma from predictions. Predictions with source parameters constrained at low frequency do not perform better than `blind' simulations, showing that extrapolation of the low

  15. A survey of microwave inverse FEL and inverse cerenkov accelerators

    NASA Astrophysics Data System (ADS)

    Marshall, T. C.; Zhang, T. B.

    1997-02-01

    A Microwave Inverse FEL Accelerator (MIFELA) and a Microwave Inverse Cerenkov Accelerator (MICA) are currently under construction at the Yale Beam Physics Laboratory. MIFELA and MICA will share the same injector, a thermionic cathode rf gun that should furnish 5 psec, 6 MeV, 0.2 nC electron pulses spaced by 350 psec, using microwave power of many MW provided from a 2.85 GHz klystron. MIFELA is to operate with ˜4 Mw of 11.4 GHz microwave power in the TE11 mode, with beam injection into each fourth rf cycle; a variable pitch and field undulator together with a guide magnetic field are present as well. MICA will operate at 2.85 GHz using an alumina-lined waveguide driven in the TM01 mode; the phase velocity is just below c, with no guide field. MIFELA produces a beam of spiralling electrons, while MICA makes an axially-directed beam. This is a survey of the operating principles of these smooth-bore "tabletop" accelerators (˜15 MeV) as they are understood prior to operation.

  16. Power regulation of kinematic control inputs for forward flying Drosophila

    NASA Astrophysics Data System (ADS)

    MacFarlane, Kenneth; Faruque, Imraan; Sean Humbert, J.

    2014-12-01

    The choices of insect wing kinematic programs is not well understood, particularly the mechanism by which an insect selects a distortion to achieve flight control. A methodology to evaluate prospective kinematic control inputs is presented based on the reachable states when control actuation was constrained to a unit of power. The method implements a computationally-derived reduced order model of the insect's flight dynamics combined with calculation of power requirement. Four kinematic inputs are evaluated based on this criterion for a Drosophila size insect in forward flight. Stroke bias is shown to be the dominant control input using this power normalized evaluation measure.

  17. Kinematic Seismic Rupture Parameters from a Doppler Analysis

    NASA Astrophysics Data System (ADS)

    Caldeira, Bento; Bezzeghoud, Mourad; Borges, José F.

    2010-05-01

    The radiation emitted from extended seismic sources, mainly when the rupture spreads in preferred directions, presents spectral deviations as a function of the observation location. This aspect, unobserved to point sources, and named as directivity, are manifested by an increase in the frequency and amplitude of seismic waves when the rupture occurs in the direction of the seismic station and a decrease in the frequency and amplitude if it occurs in the opposite direction. The model of directivity that supports the method is a Doppler analysis based on a kinematic source model of rupture and wave propagation through a structural medium with spherical symmetry [1]. A unilateral rupture can be viewed as a sequence of shocks produced along certain paths on the fault. According this model, the seismic record at any point on the Earth's surface contains a signature of the rupture process that originated the recorded waveform. Calculating the rupture direction and velocity by a general Doppler equation, - the goal of this work - using a dataset of common time-delays read from waveforms recorded at different distances around the epicenter, requires the normalization of measures to a standard value of slowness. This normalization involves a non-linear inversion that we solve numerically using an iterative least-squares approach. The evaluation of the performance of this technique was done through a set of synthetic and real applications. We present the application of the method at four real case studies, the following earthquakes: Arequipa, Peru (Mw = 8.4, June 23, 2001); Denali, AK, USA (Mw = 7.8; November 3, 2002); Zemmouri-Boumerdes, Algeria (Mw = 6.8, May 21, 2003); and Sumatra, Indonesia (Mw = 9.3, December 26, 2004). The results obtained from the dataset of the four earthquakes agreed, in general, with the values presented by other authors using different methods and data. [1] Caldeira B., Bezzeghoud M, Borges JF, 2009; DIRDOP: a directivity approach to determining

  18. High resolution 3D nonlinear integrated inversion

    NASA Astrophysics Data System (ADS)

    Li, Yong; Wang, Xuben; Li, Zhirong; Li, Qiong; Li, Zhengwen

    2009-06-01

    The high resolution 3D nonlinear integrated inversion method is based on nonlinear theory. Under layer control, the log data from several wells (or all wells) in the study area and seismic trace data adjacent to the wells are input to a network with multiple inputs and outputs and are integratedly trained to obtain an adaptive weight function of the entire study area. Integrated nonlinear mapping relationships are built and updated by the lateral and vertical geologic variations of the reservoirs. Therefore, the inversion process and its inversion results can be constrained and controlled and a stable seismic inversion section with high resolution with velocity inversion, impedance inversion, and density inversion sections, can be gained. Good geologic effects have been obtained in model computation tests and real data processing, which verified that this method has high precision, good practicality, and can be used for quantitative reservoir analysis.

  19. Lightcurve Inversion for 65 Cybele

    NASA Astrophysics Data System (ADS)

    Franco, Lorenzo; Pilcher, Frederick

    2015-07-01

    We present a shape and spin axis model for main-belt asteroid 65 Cybele. The model was obtained with lightcurve inversion process, using combined dense photometric data obtained during fifteen apparitions from 1977 to 2014 and sparse data from USNO Flagstaff. Analysis of the resulting data found a sidereal period P = 6.081434 ± 0.000005 hours and two possible pole solutions: (l = 208°, b = -7°) and (l = 27°, b = -14°) with an error of ±15 degrees.

  20. Structure and kinematics of the Bootes filament

    NASA Astrophysics Data System (ADS)

    Nasonova, O.; Karachentsev, I.; Karachentseva, V.

    2016-10-01

    Bootes filament of galaxies is a dispersed chain of groups residing on sky between the Local Void and the Virgo cluster. We consider a sample of 361 galaxies inside the sky area of RA = 13h0...18h.5 and Dec = .5°... + 10° with radial velocities VLG < 2000 km/s to clarify its structure and kinematics. In this region, 161 galaxies have individual distance estimates. We use these data to draw the Hubble relation for galaxy groups, pairs as well as the field galaxies, and to examine the galaxy distribution on peculiar velocities. Our analysis exposes the known Virgo-centric infall at RA < 14h and some signs of outflow from the Local Void at RA > 17h. According to the galaxy grouping criterion, this complex contains the members of 13 groups, 11 pairs and 140 field galaxies. The most prominent group is dominated by NGC 5846. The Bootes filament contains the total stellar mass of 2.7 ×1012 M⊙ and the total virial mass of 9.07×1013 M⊙, having the average density of dark matter to be Ωm = 0.09, i.e. a factor three lower than the global cosmic value.

  1. Kinematic analysis of rope skipper's stability

    NASA Astrophysics Data System (ADS)

    Ab Ghani, Nor Atikah; Rambely, Azmin Sham

    2014-06-01

    There are various kinds of jumping that can be done while performing rope skipping activity. This activity was always associated with injury. But, if the rope skipper can perform the activity in a right way, it is believed that the injury might be reduced. The main purpose of this paper is to observe the stability of rope skipper from a biomechanics perspective, which are the centre of mass, angle at the ankle, knee and hip joints and also the trajectory for the ipsilateral leg between the two types of skip which is one leg and two legs. Six healthy, physically active subject, two males and four females (age: 8.00±1.25 years, weight: 17.90±6.85 kg and height: 1.22±0.08 m) participated in this study. Kinematic data of repeated five cycles of rope skipping activity was captured by using Vicon Nexus system. Based on the data collected, skipping with two legs shows more stable behavior during preparation, flight and landing phases. It is concluded that landing on the balls of the feet, lowering the trajectory positions of the feet from the ground as well as flexion of each joint which would reduce the injury while landing.

  2. Turbulent Particle Pair Diffusion Using Kinematic Simulations

    NASA Astrophysics Data System (ADS)

    Malik, Nadeem

    2015-11-01

    Sweeping errors in Kinematic Simulations (KS) have been shown to be negligible in turbulent flows with extended inertial subranges up to at least 1 in KS may therefore be a genuine effect, challenging previous assumptions that in turbulence with generalized power-law energy spectra, E (k) ~k-p for 1 <= 3, locality would lead to, K ~σΔγ , where σΔ = [ <Δ2 > ]1/2 , Δ is the pair separation, v is the pair relative velocity, < > is the ensemble average, and γ = (1 + p) / 2 . For Kolmogorov turbulence this gives, K ~σΔ4 / 3 . A new analysis, supported by KS confirms that both local and non-local effects govern the pair diffusion process, leading to, K ~σΔγp , where now γp > γ for Kolmogorov turbulence, K ~σΔ1 . 53 . Thus non-local diffusional processes cannot be neglected, and this may have important consequences for the general theory of turbulence. The author acknowledge financial support from SABIC, #SB101011.

  3. Growth rate degeneracies in kinematic dynamos

    NASA Astrophysics Data System (ADS)

    Favier, B.; Proctor, M. R. E.

    2013-09-01

    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 S2T2 type of flows in spherical geometry inspired by [Dudley and James, Proc. R. Soc. London A1364-502110.1098/rspa.1989.0112 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.

  4. Feeding underground: kinematics of feeding in caecilians.

    PubMed

    Herrel, Anthony; Measey, G John

    2012-11-01

    Caecilians are limbless amphibians that have evolved distinct cranial and postcranial specializations associated with a burrowing lifestyle. Observations on feeding behavior are rare and restricted to above-ground feeding in laboratory conditions. Here we report data on feeding in tunnels using both external video and X-ray recordings of caecilians feeding on invertebrate prey. Our data show feeding kinematics similar to those previously reported, including the pronounced neck bending observed during above-ground feeding. Our data illustrate, however, that caecilians may be much faster than previously suspected, with lunge speeds of up to 7 cm sec(-1). Although gape cycles are often slow (0.67 ± 0.29 sec), rapid jaw closure is observed during prey capture, with cycle times and jaw movement velocities similar to those observed in other terrestrial tetrapods. Finally, our data suggest that gape angles may be large (64.8 ± 18°) and that gape profiles are variable, often lacking distinct slow and fast opening and closing phases. These data illustrate the importance of recording naturalistic feeding behavior and shed light on how these animals are capable of capturing and processing prey in constrained underground environments. Additional data on species with divergent cranial morphologies would be needed to better understand the co-evolution between feeding, burrowing, and cranial design in caecilians.

  5. Bat flight: aerodynamics, kinematics and flight morphology.

    PubMed

    Hedenström, Anders; Johansson, L Christoffer

    2015-03-01

    Bats evolved the ability of powered flight more than 50 million years ago. The modern bat is an efficient flyer and recent research on bat flight has revealed many intriguing facts. By using particle image velocimetry to visualize wake vortices, both the magnitude and time-history of aerodynamic forces can be estimated. At most speeds the downstroke generates both lift and thrust, whereas the function of the upstroke changes with forward flight speed. At hovering and slow speed bats use a leading edge vortex to enhance the lift beyond that allowed by steady aerodynamics and an inverted wing during the upstroke to further aid weight support. The bat wing and its skeleton exhibit many features and control mechanisms that are presumed to improve flight performance. Whereas bats appear aerodynamically less efficient than birds when it comes to cruising flight, they have the edge over birds when it comes to manoeuvring. There is a direct relationship between kinematics and the aerodynamic performance, but there is still a lack of knowledge about how (and if) the bat controls the movements and shape (planform and camber) of the wing. Considering the relatively few bat species whose aerodynamic tracks have been characterized, there is scope for new discoveries and a need to study species representing more extreme positions in the bat morphospace. PMID:25740899

  6. Scapulothoracic kinematics during tennis forehand drive.

    PubMed

    Rogowski, Isabelle; Creveaux, Thomas; Chèze, Laurence; Dumas, Raphaël

    2014-06-01

    Scapular dyskinesis is recognized as an abnormality in the kinetic chain; yet, there has been little research quantifying scapular motion during sport tasks. Tennis forehand drives of eight highly skilled tennis players were studied to assess the scapulothoracic kinematics and evaluate repeatability using video-based motion analysis. Scapulothoracic downward/upward rotation, posterior/anterior tilt, and internal/external rotation were computed using an acromial marker cluster. On average, the upward rotation, anterior tilt, and internal rotation varied from 1 degrees to 26 degrees, from 7 degrees to 32 degrees, and from 42 degrees to 100 degrees, respectively, during the tennis forehand drive. During the backswing and forward swing phases of the forehand stroke, small changes were observed for the three scapular angle values, while all angles increased rapidly during the follow-through phase. This suggests that the tennis forehand drive may contribute to scapula dyskinesis, mainly due to the great amplitude in scapulothoracic anterior tilt and internal rotation observed during the follow-through phase. Knowledge of normal scapula motion during sport tasks performed at high velocity could improve the understanding of various sport-specific adaptations and pathologies. PMID:25123001

  7. On the Kinematics of Undulator Girder Motion

    SciTech Connect

    Welch, J; /SLAC

    2011-08-18

    The theory of rigid body kinematics is used to derive equations that govern the control and measurement of the position and orientation of undulator girders. The equations form the basis of the girder matlab software on the LCLS control system. The equations are linear for small motion and easily inverted as desired. For reference, some relevant girder geometrical data is also given. Equations 6-8 relate the linear potentiometer readings to the motion of the girder. Equations 9-11 relate the cam shaft angles to the motion of the girder. Both sets are easily inverted to either obtain the girder motion from the angles or readings, or, to find the angles and readings that would give a desired motion. The motion of any point on the girder can be calculated by applying either sets of equations to the two cam-planes and extrapolating in the z coordinate using equation 19. The formulation of the equations is quite general and easily coded via matrix and vector methods. They form the basis of the girder matlab software on the LCLS control system.

  8. Kinematic mental simulations in abduction and deduction

    PubMed Central

    Khemlani, Sangeet Suresh; Mackiewicz, Robert; Bucciarelli, Monica; Johnson-Laird, Philip N.

    2013-01-01

    We present a theory, and its computer implementation, of how mental simulations underlie the abductions of informal algorithms and deductions from these algorithms. Three experiments tested the theory’s predictions, using an environment of a single railway track and a siding. This environment is akin to a universal Turing machine, but it is simple enough for nonprogrammers to use. Participants solved problems that required use of the siding to rearrange the order of cars in a train (experiment 1). Participants abduced and described in their own words algorithms that solved such problems for trains of any length, and, as the use of simulation predicts, they favored “while-loops” over “for-loops” in their descriptions (experiment 2). Given descriptions of loops of procedures, participants deduced the consequences for given trains of six cars, doing so without access to the railway environment (experiment 3). As the theory predicts, difficulty in rearranging trains depends on the numbers of moves and cars to be moved, whereas in formulating an algorithm and deducing its consequences, it depends on the Kolmogorov complexity of the algorithm. Overall, the results corroborated the use of a kinematic mental model in creating and testing informal algorithms and showed that individuals differ reliably in the ability to carry out these tasks. PMID:24082090

  9. SHIELD: Neutral Gas Kinematics and Dynamics

    NASA Astrophysics Data System (ADS)

    McNichols, Andrew; Teich, Yaron; Cannon, John M.; SHIELD Team

    2016-01-01

    The "Survey of HI in Extremely Low-mass Dwarfs" (SHIELD) is a multiwavelength, legacy-class observational study of 12 low-mass dwarf galaxies discovered in Arecibo Legacy Fast ALFA (ALFALFA) survey data products. Here we present new results of detailed kinematic analyses of these systems using multi-configuration, high spatial (˜300 pc) and spectral (0.82 - 2.46 km s-1 ch-1) resolution HI observations from the Karl G. Jansky Very Large Array. For each source, we produce velocity fields and dispersion maps using different spatial and spectral resolution representations of the data in order to attempt derivation of an inclination-corrected rotation curve. While both two- and three-dimensional fitting techniques are employed, the comparable magnitudes of velocity dispersion and projected rotation result in degeneracies that prohibit unambiguous circular velocity solutions. We thus make multiple position-velocity cuts across each galaxy to determine the maximum circular rotation velocity (≤ 30 km-1 for the survey population). Baryonic masses are calculated using single-dish H I fluxes from Arecibo and stellar masses derived from HST and Spitzer imaging. Comparison is made with total dynamical masses estimated from the position-velocity analysis. The SHIELD galaxies are contextualized on the baryonic Tully-Fisher relation.Support for this work was provided by NSF grant AST-1211683 to JMC at Macalester College.

  10. Virtual sine arm kinematic mount system

    SciTech Connect

    Xu, Z.; Randall, K.J.

    1997-09-01

    A novel kinematic mount system for a vertical focusing mirror of the soft x-ray spectroscopy beamline at the Advanced Photon Source is described. The system contains three points in a horizontal plane. Each point consists of two horizontal linear precision stages, a spherical ball bearing, and a vertical precision stage. The horizontal linear stages are aligned orthogonally and are conjoined by a spherical ball bearing, supported by the vertical linear stage at each point. The position of each confined horizontal stage is controlled by a motorized micrometer head by spring-loading the flat tip of the micrometer head onto a tooling ball fixing on the carriage of the stage. A virtual sine arm is formed by tilting the upstream horizontal stage down and the two downstream horizontal stages up by a small angle. The fine pitch motion is achieved by adjusting the upstream stage. This supporting structure is extremely steady due to a relatively large span across the supporting points and yields extremely high resolution on the pitch motion. With a one degree tilt and a microstepping motor, the authors achieved a 0.4 nanoradian resolution on the mirror pitch motion.

  11. Kinematic structure of OH/IR stars

    NASA Astrophysics Data System (ADS)

    Sun, J.; Kwok, S.

    1987-10-01

    A kinematic model is constructed for 1612 MHz OH maser emssion in OH/IR stars. The spatial distributions of OH maser intensity are calculated from a model of spherically-symmetric uniformly-expanding circumstellar shell. By comparing VLA/VLBI maps of OH/IR stars with model results, the acceptable range of combination of physical parameters M/Ve, (nH2)max, (nH2)min, fOH = [nOH]/[nH2] are derived. The theoretical relations between OH shell radius R0 and mass loss rate Mand between OH maser luminosity LOH and Mare also obtained. These relations are in good agreement with empirical relations established by Bowers et al. (1983) and Baud et al. (1983). The ranges of (nH2)max and (nOH)min under different Mrequired for operating saturated 1612 MHz OH masers are also discussed. The authors find that the OH emission phase can last over 1000 years after the termination of the asymptotic giant branch and many protoplanetary nebulae may have the characteristics of OH/IR stars.

  12. Kinematic dynamo, supersymmetry breaking, and chaos

    NASA Astrophysics Data System (ADS)

    Ovchinnikov, Igor V.; Enßlin, Torsten A.

    2016-04-01

    The kinematic dynamo (KD) describes the growth of magnetic fields generated by the flow of a conducting medium in the limit of vanishing backaction of the fields onto the flow. The KD is therefore an important model system for understanding astrophysical magnetism. Here, the mathematical correspondence between the KD and a specific stochastic differential equation (SDE) viewed from the perspective of the supersymmetric theory of stochastics (STS) is discussed. The STS is a novel, approximation-free framework to investigate SDEs. The correspondence reported here permits insights from the STS to be applied to the theory of KD and vice versa. It was previously known that the fast KD in the idealistic limit of no magnetic diffusion requires chaotic flows. The KD-STS correspondence shows that this is also true for the diffusive KD. From the STS perspective, the KD possesses a topological supersymmetry, and the dynamo effect can be viewed as its spontaneous breakdown. This supersymmetry breaking can be regarded as the stochastic generalization of the concept of dynamical chaos. As this supersymmetry breaking happens in both the diffusive and the nondiffusive cases, the necessity of the underlying SDE being chaotic is given in either case. The observed exponentially growing and oscillating KD modes prove physically that dynamical spectra of the STS evolution operator that break the topological supersymmetry exist with both real and complex ground state eigenvalues. Finally, we comment on the nonexistence of dynamos for scalar quantities.

  13. GLOBAL H I KINEMATICS IN DWARF GALAXIES

    SciTech Connect

    Stilp, Adrienne M.; Dalcanton, Julianne J.; Warren, Steven R.; Skillman, Evan; Ott, Juergen; Koribalski, Baerbel

    2013-03-10

    H I line widths are typically interpreted as a measure of interstellar medium turbulence, which is potentially driven by star formation (SF). In an effort to better understand the possible connections between line widths and SF, we have characterized H I kinematics in a sample of nearby dwarf galaxies by co-adding line-of-sight spectra after removing the rotational velocity to produce average global H I line profiles. These ''superprofiles'' are composed of a central narrow peak ({approx}6-10 km s{sup -1}) with higher-velocity wings to either side that contain {approx}10%-15% of the total flux. The superprofiles are all very similar, indicating a universal global H I profile for dwarf galaxies. We compare characteristics of the superprofiles to various galaxy properties, such as mass and measures of SF, with the assumption that the superprofile represents a turbulent peak with energetic wings to either side. We use these quantities to derive average scale heights for the sample galaxies. When comparing to physical properties, we find that the velocity dispersion of the central peak is correlated with ({Sigma}{sub HI}). The fraction of mass and characteristic velocity of the high-velocity wings are correlated with measures of SF, consistent with the picture that SF drives surrounding H I to higher velocities. While gravitational instabilities provide too little energy, the SF in the sample galaxies does provide enough energy through supernovae, with realistic estimates of the coupling efficiency, to produce the observed superprofiles.

  14. Bat flight: aerodynamics, kinematics and flight morphology.

    PubMed

    Hedenström, Anders; Johansson, L Christoffer

    2015-03-01

    Bats evolved the ability of powered flight more than 50 million years ago. The modern bat is an efficient flyer and recent research on bat flight has revealed many intriguing facts. By using particle image velocimetry to visualize wake vortices, both the magnitude and time-history of aerodynamic forces can be estimated. At most speeds the downstroke generates both lift and thrust, whereas the function of the upstroke changes with forward flight speed. At hovering and slow speed bats use a leading edge vortex to enhance the lift beyond that allowed by steady aerodynamics and an inverted wing during the upstroke to further aid weight support. The bat wing and its skeleton exhibit many features and control mechanisms that are presumed to improve flight performance. Whereas bats appear aerodynamically less efficient than birds when it comes to cruising flight, they have the edge over birds when it comes to manoeuvring. There is a direct relationship between kinematics and the aerodynamic performance, but there is still a lack of knowledge about how (and if) the bat controls the movements and shape (planform and camber) of the wing. Considering the relatively few bat species whose aerodynamic tracks have been characterized, there is scope for new discoveries and a need to study species representing more extreme positions in the bat morphospace.

  15. Feeding underground: kinematics of feeding in caecilians.

    PubMed

    Herrel, Anthony; Measey, G John

    2012-11-01

    Caecilians are limbless amphibians that have evolved distinct cranial and postcranial specializations associated with a burrowing lifestyle. Observations on feeding behavior are rare and restricted to above-ground feeding in laboratory conditions. Here we report data on feeding in tunnels using both external video and X-ray recordings of caecilians feeding on invertebrate prey. Our data show feeding kinematics similar to those previously reported, including the pronounced neck bending observed during above-ground feeding. Our data illustrate, however, that caecilians may be much faster than previously suspected, with lunge speeds of up to 7 cm sec(-1). Although gape cycles are often slow (0.67 ± 0.29 sec), rapid jaw closure is observed during prey capture, with cycle times and jaw movement velocities similar to those observed in other terrestrial tetrapods. Finally, our data suggest that gape angles may be large (64.8 ± 18°) and that gape profiles are variable, often lacking distinct slow and fast opening and closing phases. These data illustrate the importance of recording naturalistic feeding behavior and shed light on how these animals are capable of capturing and processing prey in constrained underground environments. Additional data on species with divergent cranial morphologies would be needed to better understand the co-evolution between feeding, burrowing, and cranial design in caecilians. PMID:22927194

  16. The [N II] Kinematics of R Aquarii

    NASA Technical Reports Server (NTRS)

    Hollis, J. M.; Vogel, S. N.; VanBuren, D.; Strong, J. P.; Lyon, R. G.; Dorband, J. E.

    1998-01-01

    We report a kinematic study of the symbiotic star system R Aqr derived from [N H]lambda 6584 emission observations with a Fabry-Perot imaging spectrometer. The [N II] spatial structure of the R Aqr jet, first observed circa 1977, and surrounding hourglass-shaped nebulosity, due to an explosion approximately 660 years ago, are derived from 41 velocity planes spaced at approximately 12 km/s intervals. Fabry-Perot imagery shows the elliptical nebulosity comprising the waist of the hourglass shell is consistent with a circular ring expanding radially at 55 km/s as seen at an inclination angle, i approximately 70 deg. Fabry-Perot imagery shows the two-sided R Aqr jet is collimated flow in opposite directions. The intensity-velocity structure of the strong NE jet component is shown in contrast to the amorphous SW jet component. We offer a idealized schematic model for the R Aqr jet motion which results in a small-scale helical structure forming around a larger-scale helical path. The implications of such a jet model are discussed. We present a movie showing a side-by-side comparison of the spatial structure of the model and the data as a function of the 41 velocity planes.

  17. Scapulothoracic kinematics during tennis forehand drive.

    PubMed

    Rogowski, Isabelle; Creveaux, Thomas; Chèze, Laurence; Dumas, Raphaël

    2014-06-01

    Scapular dyskinesis is recognized as an abnormality in the kinetic chain; yet, there has been little research quantifying scapular motion during sport tasks. Tennis forehand drives of eight highly skilled tennis players were studied to assess the scapulothoracic kinematics and evaluate repeatability using video-based motion analysis. Scapulothoracic downward/upward rotation, posterior/anterior tilt, and internal/external rotation were computed using an acromial marker cluster. On average, the upward rotation, anterior tilt, and internal rotation varied from 1 degrees to 26 degrees, from 7 degrees to 32 degrees, and from 42 degrees to 100 degrees, respectively, during the tennis forehand drive. During the backswing and forward swing phases of the forehand stroke, small changes were observed for the three scapular angle values, while all angles increased rapidly during the follow-through phase. This suggests that the tennis forehand drive may contribute to scapula dyskinesis, mainly due to the great amplitude in scapulothoracic anterior tilt and internal rotation observed during the follow-through phase. Knowledge of normal scapula motion during sport tasks performed at high velocity could improve the understanding of various sport-specific adaptations and pathologies.

  18. Thermally Insulating, Kinematic Tensioned-Fiber Suspension

    NASA Technical Reports Server (NTRS)

    Voellmer, George M.

    2004-01-01

    A salt pill and some parts of a thermally insulating, kinematic suspension system that holds the salt pill rigidly in an adiabatic-demagnetization refrigerator (ADR) is presented. "Salt pill" in this context denotes a unit comprising a cylindrical container, a matrix of gold wires in the container, and a cylinder of ferric ammonium alum (a paramagnetic salt) that has been deposited on the wires. The structural members used in this system for both thermal insulation and positioning are aromatic polyamide fibers (Kevlar(R) or equivalent) under tension. This suspension system is designed to satisfy several special requirements to ensure the proper operation of the ADR. These requirements are to (1) maintain the salt pill at a specified position within the cylindrical bore of an electromagnet; (2) prevent vibrations, which would cause dissipation of heat in the salt pill; and (3) minimize the conduction of heat from the electromagnet bore and other neighboring objects to the salt pill; all while (4) protecting the salt pill (which is fragile) against all tensile and bending loads other than those attributable to its own weight. In addition, the system is required to consist of two subsystems -- one for the top end and one for the bottom end of the salt pill -- that can be assembled and tensioned separately from each other and from the salt pill, then later attached to the salt pill.

  19. Virtual human hand: model and kinematics.

    PubMed

    Peña-Pitarch, Esteban; Falguera, Neus Ticó; Yang, Jingzhou James

    2014-04-01

    The human hand plays an important role in daily life. It is the interface between the human and the exterior world by positioning, orienting, touching and grasping objects. The human hand has multiple degrees of freedom (DOFs) to enable mobility and dexterity. A virtual human hand model can be inserted into CAD (Computer Aided Design) models to assess the manipulation capabilities in the early design stage to reduce design time and cost. Joystick assessment is one of the important design cases. This study is a first step towards a comprehensive hand simulation tool to simulate the manipulation and grasping of objects. This paper presents a novel 25 DOFs' hand skeletal model based on hand anatomy and hand kinematics: (1) joint range of motion, (2) Denavit-Hartenberg method to define the joint relationship and (3) finger workspace determination. Novelty for this hand model includes arching the palm with the four DOFs added in the carpometacarpal and wrist joints for the ring and small fingers.

  20. KINEMATICAL AND CHEMICAL VERTICAL STRUCTURE OF THE GALACTIC THICK DISK. I. THICK DISK KINEMATICS ,

    SciTech Connect

    Moni Bidin, C.; Carraro, G.; Mendez, R. A.

    2012-03-10

    The variation of the kinematical properties of the Galactic thick disk with Galactic height Z is studied by means of 412 red giants observed in the direction of the south Galactic pole up to 4.5 kpc from the plane. We confirm the non-null mean radial motion toward the Galactic anticenter found by other authors, but we find that it changes sign at |Z| = 3 kpc, and the proposed inward motion of the local standard of rest alone cannot explain these observations. The rotational velocity decreases with |Z| by -30 km s{sup -1} kpc{sup -1}, but the data are better represented by a power law with index 1.25, similar to that proposed from the analysis of Sloan Digital Sky Survey data. All the velocity dispersions increase with |Z|, but the vertical gradients are small. The dispersions grow proportionally, with no significant variation of the anisotropy. The ratio {sigma}{sub U}/{sigma}{sub W} = 2 suggests that the thick disk could have formed from a low-latitude merging event. The vertex deviation increases with Galactic height, reaching {approx}20 Degree-Sign at |Z| = 3.5 kpc. The tilt angle also increases, and the orientation of the ellipsoid in the radial-vertical plane is constantly intermediate between the alignment with the cylindrical and the spherical coordinate systems. The tilt angle at |Z| = 2 kpc coincides with the expectations of MOdified Newtonian Dynamics, but an extension of the calculations to higher |Z| is required to perform a conclusive test. Finally, between 2.5 and 3.5 kpc we detect deviations from the linear trend of many kinematical quantities, suggesting that some kinematical substructure could be present.