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1

JFKengine: A Jacobian and Forward Kinematics Generator  

SciTech Connect

During robot path planning and control the equations that describe the robot motions are determined and solved. Historically these expressions were derived analytically off-line. For robots that must adapt to their environment or perform a wide range of tasks, a way is needed to rapidly re-derive these expressions to take into account the robot kinematic changes, such as when a tool is added to the end-effector. The JFKengine software was developed to automatically produce the expressions representing the manipulator arm motion, including the manipulator arm Jacobian and the forward kinematic expressions. Its programming interface can be used in conjunction with robot simulation software or with robot control software. Thus, it helps to automate the process of configuration changes for serial robot manipulators. If the manipulator undergoes a geometric change, such as tool acquisition, then JFKengine can be invoked again from the control or simulation software, passing it parameters for the new arm configuration. This report describes the automated processes that are implemented by JFKengine to derive the kinematic equations and the programming interface by which it is invoked. Then it discusses the tree data structure that was chosen to store the expressions, followed by several examples of portions of expressions as represented in the tree. The C++ classes and their methods that implement the expression differentiation and evaluation operations are described. The algorithms used to construct the Jacobian and forward kinematic equations using these basic building blocks are then illustrated. The activity described in this report is part of a larger project entitled ''Multi-Optimization Criteria-Based Robot Behavioral Adaptability and Motion Planning'' that focuses on the development of a methodology for the generalized resolution of robot motion equations with time-varying configurations, constraints, and task objective criteria. A specific goal of this project is the implementation of this generalized methodology in a single general code that would be applicable to the motion planning of a wide class of systems and would automate many of the processes involved in developing and solving the motion planning and controls equations. This project is funded by the U.S. Department of Energy's Environmental Management Science Program (DOE-EMSP) as project EMSP no. 82794 and is transitioning to the DOE-Office of Biological and Environmental Research (OBER) as per FY-02.

Fischer, K.N.

2003-02-13

2

Compressed implicit Jacobian scheme for elastic full-waveform inversion  

NASA Astrophysics Data System (ADS)

We present a regularized Gauss-Newton (GN) inversion method for solving the elastic full-waveform inversion problem in the frequency domain. The main bottleneck of this method is the Jacobian matrix storage and the computational cost of calculating the GN step (the inner-loop calculation). In this work, we managed to reduce the memory usage by calculating the Jacobian matrix on the fly in each inner-loop iteration. By doing so the computational cost of calculating the GN step increases; however, this overhead is mitigated by compressing the field matrices using the adaptive cross approximation scheme. For some cases, this compressed implicit Jacobian scheme may even speed-up the GN step calculation and further regularizes the GN method. As examples, we present inversion results of cross-well seismic and surface seismic data.

Abubakar, A.; Li, M.; Lin, Y.; Habashy, T. M.

2012-06-01

3

Inversion without Explicit Jacobian Calculations in Electrical Impedance Tomography  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

4

Style-based inverse kinematics  

Microsoft Academic Search

This paper presents an inverse kinematics system based on a learned model of human poses. Given a set of constraints, our system can produce the most likely pose satisfying those constraints, in real-time. Training the model on different input data leads to different styles of IK. The model is represented as a probability distribution over the space of all possible

Keith Grochow; Steven L. Martin; Aaron Hertzmann; Zoran Popovic

2004-01-01

5

An inverse kinematic solution for kinematically redundant robot manipulators  

Microsoft Academic Search

The computation of the sequence of joint motion on the basis of the Cartesian motion of an interested member is addressed by an inverse kinematic analysis that is based on a Newton-Raphson numerical procedure. This procedure may be applied to the solution of the inverse kinematic problem for a manipulator of any mechanical configuration without having to derive a closed

S.-Y. Oh; M. Bach; D. Orin

1984-01-01

6

An inverse kinematic solution for kinematically redundant robot manipulators  

NASA Astrophysics Data System (ADS)

The computation of the sequence of joint motion on the basis of the Cartesian motion of an interested member is addressed by an inverse kinematic analysis that is based on a Newton-Raphson numerical procedure. This procedure may be applied to the solution of the inverse kinematic problem for a manipulator of any mechanical configuration without having to derive a closed form solution beforehand. The technique is applicable to redundant manipulators, since additional constraints on other members, as well as on the end effector, may be imposed. The approach is presently applied to a seven-degree-of-freedom manipulator, and its obstacle-avoidance capability is demonstrated.

Oh, S.-Y.; Bach, M.; Orin, D.

7

Fatigue Exploitation in an Inverse Kinematics Framework  

E-print Network

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

Rodríguez, Inmaculada

8

Wrist-Partitioned, Inverse Kinematic Accelerations and Manipulator Dynamics  

Microsoft Academic Search

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

John M. Hollerbach; Gideon Sahar

1983-01-01

9

Directed Neutron Beams From Inverse Kinematic Reactions  

SciTech Connect

Kinematic focusing of an emitted fairly mono-energetic neutron beam by the use of inverse-kinematic reactions, i.e. where the projectile mass is greater than the target atom's mass, can provide for the utilization of a significant fraction of the fast neutron yield and also provide for a safer radiation environment. We examine the merit of various neutron production reactions and consider the practicalities of producing the primary beam using the suitable accelerator technologies. Preliminary progress at the NSWC-Carderock Positive Ion Accelerator Facility is described. Possible important applications for this type of neutron-based system can be both advanced medical imaging techniques and active ''stand-off'' interrogation of contraband items.

Vanhoy, J. R. [Department of Physics, 572C Holloway Road, US Naval Academy, Annapolis, MD 21402 (United States); Guardala, N. A. [Positive Ion Accelerator Facility, NSWC-Carderock Division, West Bethesda, MD 20817 (United States); Glass, G. A. [Louisiana Accelerator Center, Physics Department, University of Louisiana at Lafayette, Louisiana 70504 (United States)

2011-06-01

10

An adaptive inverse kinematics algorithm for robot manipulators  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

11

Computational neural learning formalisms for manipulator inverse kinematics  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

12

Kinematics modeling of eight-wheel lunar rover  

Microsoft Academic Search

This paper presents the kinematics modeling method of eight-wheel torsion bar rocker-bogie lunar rover. Forward kinematics modeling consists of the Jacobian matrices of the wheels, it could deduce the position and attitude of the rover. Inverse kinematics modeling could work out the speed of the wheels by using the speed of the rover, so as to get the anticipated position

Chen Lei; Ma Jie; Gao Haibo

2008-01-01

13

Production of Radioactive Nuclides in Inverse Reaction Kinematics  

E-print Network

Efficient production of short-lived radioactive isotopes in inverse reaction kinematics is an important technique for various applications. It is particularly interesting when the isotope of interest is only a few nucleons away from a stable isotope. In this article production via charge exchange and stripping reactions in combination with a magnetic separator is explored. The relation between the separator transmission efficiency, the production yield, and the choice of beam energy is discussed. The results of some exploratory experiments will be presented.

E. Traykov; A. Rogachevskiy; U. Dammalapati; P. Dendooven; O. C. Dermois; K. Jungmann; C. J. G. Onderwater; M. Sohani; L. Willmann; H. W. Wilschut; A. R. Young

2006-08-08

14

Study on the effect of parameters on source kinematic inversion  

NASA Astrophysics Data System (ADS)

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

Wen, J.; Chen, X.

2011-12-01

15

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

PubMed

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

de Angulo, Vicente Ruiz; Torras, Carme

2008-12-01

16

Kinematic Waveform Inversion: Application in Southwest Iberia Seismicity  

NASA Astrophysics Data System (ADS)

The seismic activity that affects the Portuguese territory occurs mainly and more frequently offshore, in the south and southwest of Mainland Portugal. The study of the Portuguese seismicity is conditioned by the poor azimuthal coverage, due to the geographic location of Portugal, and by the large sedimentary basin west of the straight of Gibraltar (Cadiz Basin). In this work we focus on the study of regional seismicity in Portugal (mostly offshore earthquakes) using a recently developed package - the KIWI (Kinematic Waveform Inversion) tools. This new technique performs point and finite source inversions at regional distances. The KIWI routine is a multi-step approach composed of 3 steps, finding different source parameters at different steps. At first, we assume a point source approximation. We initially retrieve the focal mechanism of the earthquake (strike, dip, and rake), the seismic scalar moment M0 and the depth. This inversion step is performed in the spectral domain, by fitting amplitude spectra. In the second step, compressive and dilatation quadrants are retrieved, which is carried out in the time domain. Refined latitude and longitude for the centroid, as well as an earthquake origin time, are also given at this time. The final step of the inversion consists of a simplified finite-fault inversion. We assume the eikonal source model, and determine parameters such as the fault plane orientation (discrimination between fault and auxiliary plane), radius (rupture extension), nucleation point coordinates (indicative of directivity effects) and average rupture velocity of the earthquake. This inversion is performed in the frequency domain by fitting amplitude spectra in a wider frequency band (including higher frequencies). This multi-step approach has the advantage of using different inversion methods, seismic phases and range of frequencies to infer specific parameters. In this work we study 17 regional earthquakes occurred in Southwest Iberia between 2007 and 2009 with moderate magnitude (3.3 to 4.4). The small magnitude of these earthquakes prevents their study with the third step of the algorithm. The solutions obtained are evaluated by a quality criteria and compared with other moment tensor solutions. The quality factor is based on the number of stations and on the misfit between the recorded and the synthetic waveforms. Apart from this study another offshore event was analyzed. The earthquake occurred SW of St Vincent Cape on February 12, 2007 with Mw 5.9. In this study the KIWI tools were employed to infer both the point and finite source parameters of this earthquake. The results of the kinematic source inversion step indicate that the 2007 HAP earthquake ruptured a plane trending WNW-ESE, whereas previous studies suggest that the conjugate fault plane (ENE-WSW) is the true rupture plane. The proposed solution also indicates that the earthquake occurred within the SWIM fault-zone. However, the 46° dip is difficult to reconcile with the sub-vertical nature of the SWIM faults.

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

2011-12-01

17

First application of the ?-summing technique in inverse kinematics  

NASA Astrophysics Data System (ADS)

The ?-summing technique was successfully implemented for the first time in inverse kinematics using the NSCL Summing NaI(Tl) detector at the Nuclear Science Laboratory of the University of Notre Dame. This new method offers a way to measure (p,?) and (?,?) reactions on unstable nuclei, which are critical for an improved understanding of nucleosynthesis. As a proof of principle, the well-known resonances at Ec.m.=956 keV in the p(27Al,?)28Si reaction and at Ec.m.=1400 keV in the p(58Ni,?)59Cu reaction were measured and their resonance strengths were deduced. The values of the present work agree well with the reported literature values, demonstrating the viability of the technique.

Quinn, S. J.; Spyrou, A.; Simon, A.; Battaglia, A.; Bowers, M.; Bucher, B.; Casarella, C.; Couder, M.; DeYoung, P. A.; Dombos, A. C.; Greene, J. P.; Görres, J.; Kontos, A.; Li, Q.; Long, A.; Moran, M.; Paul, N.; Pereira, J.; Robertson, D.; Smith, K.; Smith, M. K.; Stech, E.; Talwar, R.; Tan, W. P.; Wiescher, M.

2014-09-01

18

An open mapping theorem using unbounded generalized Jacobians  

Microsoft Academic Search

In this paper, three key theorems (the open mapping theorem, the inverse function theorem, and the implicit function theorem) for contin- uously differentiable maps are shown to hold for nonsmooth continuous maps which are not necessarily Lipschitz continuous. The significance of these extensions is that they are given using generalized Jacobians, called approximate Jacobians. The approximate Jacobian which replaces the

V. Jeyakumar; D. T. Luc

2002-01-01

19

A computationally efficient approach for Jacobian approximation of image based visual servoing for joint limit avoidance  

Microsoft Academic Search

A dynamic Newton's approximation based esti- mation scheme is proposed for image-based visual servoing (IBVS) of a redundant manipulator. The estimation scheme approximates the kinematic Jacobian from joint space to vision space online. The estimated Jacobian is used for redundancy resolution with weighted least norm solution. This work dis- cusses the kinematic limit avoidance with estimated Jacobian for a 7

Indrazno Siradjuddin; T. M. McGinnity; Sonya Coleman; Laxmidhar Behera

2011-01-01

20

Inelastic Proton Scattering on 21Na in Inverse Kinematics  

NASA Astrophysics Data System (ADS)

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

Austin, Roby

2009-10-01

21

Manipulator inverse kinematics control based on particle swarm optimization neural network  

NASA Astrophysics Data System (ADS)

The inverse kinematics control of a robotic manipulator requires solving non-linear equations having transcendental functions and involving time-consuming calculations. Particle Swarm Optimization (PSO), which is based on the behaviour of insect swarms and exploits the solution space by taking into account the experience of the single particle as well as that of the entire swarm, is similar to the genetic algorithm (GA) in that it performs a structured randomized search of an unknown parameter space by manipulating a population of parameter estimates to converge on a suitable solution. In this paper, PSO is firstly proposed to optimize feed-forward neural network for manipulator inverse kinematics. Compared with the results of the fast back propagation learning algorithm (FBP), conventional GA genetic algorithm based elitist reservation (EGA), improved GA (IGA) and immune evolutionary computation (IEC), the simulation results verify the particle swarm optimization neural network (PSONN) is effective for manipulator inverse kinematics control.

Wen, Xiulan; Sheng, Danghong; Guo, Jing

2008-10-01

22

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

SciTech Connect

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

Pain, S. D. [Rutgers University; Bardayan, Daniel W [ORNL; Blackmon, Jeff C [ORNL; Chae, K. Y. [University of Tennessee, Knoxville (UTK); Chipps, K. [Colorado School of Mines, Golden; Cizewski, J. A. [Rutgers University; Hatarik, Robert [Rutgers University; Johnson, Micah [ORNL; Jones, K. L. [University of Tennessee, Knoxville (UTK); Kapler, R. [University of Tennessee, Knoxville (UTK); Kozub, R. L. [Tennessee Technological University; Livesay, Jake [ORNL; Matei, Catalin [Oak Ridge Associated Universities (ORAU); Moazen, Brian [University of Tennessee, Knoxville (UTK); Nesaraja, Caroline D [ORNL; O'Malley, Patrick [Rutgers University; Smith, Michael Scott [ORNL; Swan, T. P. [University of Surrey, UK; Thomas, J. S. [Rutgers University; Wilson, Gemma L [ORNL

2009-01-01

23

Inverse Kinematics of Robot Manipulators with Multiple Moving Control Points  

Microsoft Academic Search

The growing research area of physical Human-Robot Interaction (pHRI) claims for safe robot control algorithms in the presence\\u000a of humans. Managing kinematic redundancy via fast techniques is also mandatory for interaction tasks with humans. It is worth\\u000a noticing that control points on a manipulator can change, e.g., depending on possible multiple collisions (intentional or\\u000a accidental) with the interacting users. An

Agostino De Santis; Bruno Siciliano

24

Kinematic earthquake rupture inversion in the frequency domain  

NASA Astrophysics Data System (ADS)

We develop a frequency-based approach to earthquake slip inversion that requires no prior information on the rupture velocity or slip-rate functions. Because the inversion is linear and is performed separately at each frequency, it is computationally efficient and suited to imaging the finest resolvable spatial details of rupture. We demonstrate the approach on synthetic seismograms based on the Source Inversion Validation Exercise 1 (SIV1) of a crustal Mw 6.6 strike-slip earthquake recorded locally. A robust inversion approach is obtained by applying a combination of damping, smoothing and forcing zero slip at the edge of the fault model. This approach achieves reasonable data fits, overall agreement to the SIV1 model, including slip-rate functions of each subfault, from which its total slip, slip time history and rupture velocity can be extracted. We demonstrate the method's robustness by exploring the effects of noise, random timing errors, and fault geometry errors. The worst effects on the inversion are seen from errors in the assumed fault geometry.

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

2014-11-01

25

Inverse kinematics of binary manipulators by using the continuous-variable-based optimization method  

Microsoft Academic Search

Hyper redundancy, high reliability, and high task repeatability are the main advantages of binary manipulators over conventional manipulators with continuous joints, especially when manipulators are operated under tough and complex work conditions. The precise and complex movement of a binary manipulator necessitates many modules. In this case, numerically efficient inverse kinematics algorithms for binary manipulators usually require impractically large memory

Yoon Young Kim; Gang-Won Jang; Sang Jun Nam

2006-01-01

26

Attractor-based computation with reservoirs for online learning of inverse kinematics  

Microsoft Academic Search

We implement completely data driven and e!cient online learning from temporally correlated data in a reservoir network setup. We show that attractor states rather than transients are used for computation when learning inverse kinematics for the redundant robot arm PA-10. Our findings shade also light on the role of output feedback. In robotics, learning is typically constrained by limited resources

R. Felix Reinhart; Jochen J. Steil

2009-01-01

27

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

NASA Technical Reports Server (NTRS)

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

Tahmasebi, Farhad

2004-01-01

28

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

29

Frequency Domain Inversion of Strong Motions: Application to the Blind Test for Kinematic Source Inversion (EC-project SPICE)  

NASA Astrophysics Data System (ADS)

We have applied a frequency domain inversion method to the Blind Test for Kinematic Source Inversion (Mai et al., EC-project SPICE). The parameters describing the rupture process are the local slip, the rupture time and the rise time. Green's functions are numerically evaluated with the Discrete Wavenumber Method. A Generalized Least Square Inversion is used to retrieve the final source parameters. The inversion procedure is based on an iterative Quasi Newton Algorithm (Tarantola and Valette, 1982). A spatial smoothing constraint is introduced through the covariance matrice of the parameter space vector to prevent from unrealistic slip value bumps between two neighbouring subfaults. The resolution matrice illustrates how well the inverse problem can be solved by the data. The values of the resolution are used in a relative way to compare the resolution of different parts of the fault. Since the problem is intrinsically nonlinear the final results depends on the a priori chosen initial parameterization. In order to analyze the non-uniqueness of the solution, we therefore test a population of starting models.

Causse, M.; Cotton, F.; Campillo, M.

2007-12-01

30

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

USGS Publications Warehouse

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

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

2004-01-01

31

Invariant Mass Spectroscopy of 23O via the ( p, p') Reaction in Inverse Kinematics  

NASA Astrophysics Data System (ADS)

The neutron-rich oxygen isotope 23O has been investigated via proton inelastic scattering on a liquid hydrogen target at 63.5 MeV/nucleon. The invariant mass method in inverse kinematics was employed to reconstruct the energy spectrum. A sharp resonance state was observed at 42(5) keV above the neutron threshold. A comparison of the differential cross section leading to this state with a microscopic DWBA calculation allowed a J ? assignment of 5/2+ for this state.

Satou, Y.; Tshoo, K.; Bhang, H.; Choi, S.; Hwang, J. W.; Nakamura, T.; Kondo, Y.; Nakayama, Y.; Kobayashi, N.; Tanaka, K. N.; Deguchi, S.; Kawada, Y.; Tanaka, N.; Motobayashi, T.; Sakurai, H.; Otsu, H.; Aoi, N.; Takeuchi, S.; Yoneda, K.; Togano, Y.; Ishihara, M.; Shimoura, S.; Kobayashi, T.; Matsushita, M.; Honda, T.; Sumikama, T.; Miyashita, Y.; Yoshinaga, K.; Orr, N. A.; Marques, F. M.; Gibelin, J.; Delaunay, F.; Sohler, D.; Zheng, T.; Li, Z. H.; Cao, Z. X.

2013-03-01

32

Kinematic modeling of mobile robot with rocker-bogie link structure  

NASA Astrophysics Data System (ADS)

A method for kinematic modeling of a mobile robot with rocker-bogie link mechanism was described. By using the well-known concept of the instantaneous coordinates, it derives the kinematic model for the full six degree of freedom motion including the x, y, and z motions and the pitch, roll, and yaw rotations. The kinematic model here implies both of the forward and the inverse kinematic equations. The forward kinematic equation with the wheel Jacobian matrices can be used to obtain the robot position and orientation from the measured wheel velocities and the rocker-bogie joint angles. On the contrary, the inverse kinematic equation implies a resulting robot motions consisting of body velocity and turning rate from the individual wheel velocities. Through the computer simulation, the kinematic model of the mobile robot was verified.

Gang, Taig-Gi; Yi, Soo-Yeong

2005-12-01

33

Kinematically redundant robot manipulators  

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

34

Integrated Analytic and Linearized Inverse Kinematics for Precise Full Body Interactions  

NASA Astrophysics Data System (ADS)

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

Boulic, Ronan; Raunhardt, Daniel

35

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

NASA Technical Reports Server (NTRS)

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

Naccarato, Frank; Hughes, Peter

1989-01-01

36

Formulation of Manipulator Jacobian Using the Velocity Similarity Principle.  

National Technical Information Service (NTIS)

A velocity similarity principle is presented and used to derive several useful forms of the Jacobian matrix for the manipulator from its basic kinematic equations in 4 x 4 matrix form. The zero reference position representation is used and, therefore, the...

K. C. Gupta, R. Ma

1990-01-01

37

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

NASA Astrophysics Data System (ADS)

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

Xu, Wenfu; She, Yu; Xu, Yangsheng

2014-12-01

38

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

39

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

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

40

A novel on-line training solution using a Radial Basis Function Network to modify the inverse kinematic approximation of a robot-vision system  

Microsoft Academic Search

This paper describes a new practical approach for approximating the inverse kinematics of a manipulator using an RBFN (Radial Basis Function Network). This neural network with its inherent learning ability can be an effective alternative solution for the inverse kinematics problem where traditional methods are impractical because the manipulator geometry cannot be easily determined, e.g. in a robot-vision system. However,

Bach H. Dinh; Duy V. Hoang; Duy C. Huynh

2011-01-01

41

Robotica (1994) volume 12, pp 421-430. 1994 Cambridge University Press Inverse kinematics of six-degree of freedom "general"  

E-print Network

Robotica (1994) volume 12, pp 421-430. © 1994 Cambridge University Press Inverse kinematics of six. Bidaud Laboratoire de Robotique de Paris, Universite Pierre et Marie Curie, Tour 66, 2eme etage, 4 Place to the inverse kinematics problem of the GMF Arc Mate welding manipulator. In spite of its geometry

Mavroidis, Constantinos

42

Interservice/Industry Training, Simulation, and Education Conference (I/ITSEC) 2008 Blended Inverse Kinematics: Delta3D System Utilization  

E-print Network

School Monterey, CA mjguerre@nps.edu, cjdarken@nps.edu ABSTRACT Traditional inverse kinematics systems to point in the desired direction for aiming or shooting. It does all of this and more without burdening Michael Guerrero is a research associate at the MOVES Institute of the Naval Postgraduate School

Darken, Christian J.

43

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

SciTech Connect

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

Unseren, M.A.

1993-04-01

44

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

45

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

E-print Network

A method and system has been developed to solve the kinematic redundancy for a humanoid redundant manipulator based on forward kinematic equation and the optimization of human-like constraints. The Multiple Objective ...

Thomann, Derik (Derik S.)

2005-01-01

46

LENDA: A low energy neutron detector array for experiments with radioactive beams in inverse kinematics  

NASA Astrophysics Data System (ADS)

The Low Energy Neutron Detector Array (LENDA) is a neutron time-of-flight (TOF) spectrometer developed at the National Superconducting Cyclotron Laboratory (NSCL) for use in inverse kinematics experiments with rare isotope beams. Its design has been motivated by the need to study the spin-isospin response of unstable nuclei using (p,n) charge-exchange reactions at intermediate energies (>100 MeV/u). It can be used, however, for any reaction study that involves emission of low energy neutrons (150 keV to 10 MeV). The array consists of 24 plastic scintillator bars and is capable of registering the recoiling neutron energy and angle with high detection efficiency. The neutron energy is determined by the time-of-flight technique, while the position of interaction is deduced using the timing and energy information from the two photomultipliers of each bar. A simple test setup utilizing radioactive sources has been used to characterize the array. Results of test measurements are compared with simulations. A neutron energy threshold of <150 keV, an intrinsic time (position) resolution of ˜ 400 ps (˜ 6 cm) and an efficiency >20% for neutrons below 4 MeV have been obtained.

Perdikakis, G.; Sasano, M.; Austin, Sam M.; Bazin, D.; Caesar, C.; Cannon, S.; Deaven, J. M.; Doster, H. J.; Guess, C. J.; Hitt, G. W.; Marks, J.; Meharchand, R.; Nguyen, D. T.; Peterman, D.; Prinke, A.; Scott, M.; Shimbara, Y.; Thorne, K.; Valdez, L.; Zegers, R. G. T.

2012-09-01

47

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

48

Resonant scattering of 22Na + p studied by the thick-target inverse-kinematic method  

NASA Astrophysics Data System (ADS)

Background: In presolar low-density graphite grains, an extraordinarily large 22Ne/20Ne ratio or even nearly pure 22Ne is found, pointing to the condensation of radioactive 22Na in grains. Supernovae and neon-rich novae are the main events that produce 22Na via the explosive hydrogen burning process. The 22Na(p, ?)23Mg reaction is one of the key reactions that influences the 22Na abundance in ejecta.Purpose:The present work aims to explore the proton resonant states in 23Mg relevant to the astrophysical 22Na(p, ?)23Mg reaction. The determined 23Mg resonant parameters can be used to evaluate the 22Na(p, ?)23Mg reaction rate.Method:A low-energy 22Na radioactive ion beam is produced via the 1H(22Ne, 22Na)n reaction, and used to measure the experimental excitation function of the 22Na + p resonant scattering with a conventional thick-target inverse kinematic method. R-matrix analysis is applied to deduce the 23Mg resonance parameters from the experimental excitation function.Results: Three proton resonance states in 23Mg are observed. Spins/parities and the proton partial widths are determined. The deduced excitation energies agree with the compiled values.Conclusions: The new spin and parity assignments allow us to perform a shell-model calculation of the ? widths of the 23Mg resonant states for the evaluation of the 22Na(p, ?)23Mg astrophysical reaction rate. The two s-wave resonant states established in this work at 8.793 and 8.916 MeV in 23Mg, respectively, increase the total reaction rate by about 5% at a temperature greater than 2 GK.

Jin, S. J.; Wang, Y. B.; Su, J.; Yan, S. Q.; Li, Y. J.; Guo, B.; Li, Z. H.; Zeng, S.; Lian, G.; Bai, X. X.; Liu, W. P.; Yamaguchi, H.; Kubono, S.; Hu, J.; Kahl, D.; Jung, H. S.; Moon, J. Y.; Lee, C. S.; Teranishi, T.; Wang, H. W.; Ishiyama, H.; Iwasa, N.; Komatsubara, T.; Brown, B. A.

2013-09-01

49

Efficient calculation of sparse Jacobians  

SciTech Connect

This paper describes a new approach for efficient Jacobian calculation using automatic differentiation. This approach obviates the need for vector accumulation by reducing certain parts of the computational graph representing the system of equations, allowing the Jacobian to be accumulated through a series of scalar operations. The advantages of this new approach include low spatial complexity, the ability to adapt to available memory if resources are limited, the ability to efficiently handle linear equations in a convenient manner, and low computational complexity. In addition, this approach is particularly well suited for evaluations within an interpretive environment. The approach can be applied to both the forward and reverse modes of automatic differentiation.

Tolsma, J.E.; Barton, P.I.

1999-07-01

50

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

51

Recurrent neural associative learning of forward and inverse kinematics for movement generation of the redundant PA10 robot  

Microsoft Academic Search

\\\\ We present a connectionist approach to learn for-
\\u000d\\u000award and redundant inverse kinematics in a single recurrent
\\u000d\\u000anetwork. The network architecture extends the reservoir com-
\\u000d\\u000aputing idea, i.e. to read out the state of a fixed dynamic
\\u000d\\u000asystem, into an associative setting, which learns the forward
\\u000d\\u000aand backward mapping simultaneously.

F. R. Reinhart; Jochen J. Steil

2008-01-01

52

Solving the Differential Biochemical Jacobian from Metabolomics Covariance Data  

PubMed Central

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

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

2014-01-01

53

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

USGS Publications Warehouse

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

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

2005-01-01

54

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

55

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

E-print Network

Shkolnik and Russ Tedrake Computer Science and Artificial Intelligence Laboratory Massachusetts Institute to formulate a function to compute forward kinematics of the center of mass of the robot as a function in achieving a step leg trajectory. In simulation, this control allows the robot to perform significantly more

Tedrake, Russ

56

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

57

Resolved motion rate control of space manipulators with generalized Jacobian matrix  

Microsoft Academic Search

The authors establish a control method for space manipulators taking dynamical interaction between the manipulator arm and the base satellite into account. The kinematics of free-flying multibody systems is investigated by introducing the momentum conservation law into the formulation and a novel Jacobian matrix in generalized form for space robotic arms is derived. The authors develop a control method for

YOJI UMETANI; KAZUYA YOSHIDA

1989-01-01

58

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

NASA Astrophysics Data System (ADS)

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

Lucca, Ernestina; Festa, Gaetano; Emolo, Antonio

2010-05-01

59

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

60

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

61

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

NASA Technical Reports Server (NTRS)

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

Williams, Robert L., II

1992-01-01

62

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

NASA Technical Reports Server (NTRS)

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

Williams, Robert L., II

1992-01-01

63

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

64

Inverse Bayesian Estimation of Gravitational Mass Density in Galaxies from Missing Kinematic Data  

E-print Network

In this paper we focus on a type of inverse problem in which the data is expressed as an unknown function of the sought and unknown model function (or its discretised representation as a model parameter vector). In particular, we deal with situations in which training data is not available. Then we cannot model the unknown functional relationship between data and the unknown model function (or parameter vector) with a Gaussian Process of appropriate dimensionality. A Bayesian method based on state space modelling is advanced instead. Within this framework, the likelihood is expressed in terms of the probability density function ($pdf$) of the state space variable and the sought model parameter vector is embedded within the domain of this $pdf$. As the measurable vector lives only inside an identified sub-volume of the system state space, the $pdf$ of the state space variable is projected onto the space of the measurables, and it is in terms of the projected state space density that the likelihood is written; ...

Chakrabarty, Dalia

2014-01-01

65

Investigating the postseismic deformation of the 2010 Maule Chile megathrust; insights from kinematic inversions  

NASA Astrophysics Data System (ADS)

In the years following great earthquakes, surface deformation around the rupture area occurs at high and variable rates. Rapidly decaying (lasting for days or years) postseismic deformation in the near-field of the rupture may result from fault afterslip caused by the frictional response of the subduction interface to the coseismic stress perturbation. The spatio-temporal evolution of the rapidly decaying deformation has, so far, been difficult to determine based on available observations and present knowledge of the afterslip and related mechanisms. The 2010 Maule earthquake (Mw8.8) that affected about 500 km of the Nazca-South America plate boundary in south-central Chile was the first great and presumably gap-filling event to be captured by modern space-geodetical monitoring networks. The density of GPS coverage (both campaign and continuous daily solutions) alongside the rupture zone of the Maule event provides an excellent opportunity to probe the postseismic deformation along a daily timescale. Inverting the GPS data from 54 stations to model daily slip on the plate interface reveals how the afterslip distribution jumps around the interface in a somewhat chaotic fashion. Inversion results are validated by aftershock locations, which tend to line up in between patches of high slip on the interface. For certain patches in the slip model we see considerable variability in the slip direction and pulses of acceleration on the afterslip; the cumulative afterslip of the first 430 days released in one seismic event would have a Mw of 8.4. So far, we have solely inverted for afterslip along the plate interface in modelling the postseismic process. Our ongoing research involves investigating the contribution of other processes such as crustal fault slip, viscoelasticity and poroelasticity to the surface deformation field.

Bedford, J.; Moreno, M.; Keiding, M.; Heidbach, O.; Oncken, O.; Lange, D.; Baez, J. C.; Maule GPS Team

2012-04-01

66

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

67

Kinematics Analysis of a Six-Wheeled Mobile Robot  

Microsoft Academic Search

The paper analysis a kinematic model for a wheeled mobile robot (WMR) traversing uneven terrain. A new form of the kinematics for wheeled mobile robot is deduced, through analyzing Jacobian matrices of individual wheel and rearranging the variables. The performance and characters of the kinematic formulation are explained using physical conception. A new method is proposed to set up the

Yong Chang; Dalong Tan; Hongguang Wang; Shugen Ma

2006-01-01

68

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

PubMed

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

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

2012-05-01

69

Singularity analysis of closed-loop kinematic chains  

Microsoft Academic Search

The different kinds of singularities encountered in closed-loop kinematics chains are analyzed. A general classification of these singularities in three main groups, which is based on the properties of the Jacobian matrices of the chain, is described. The identification of the singular configurations is particularly relevant for hard automation modules or robotic devices based on closed kinematic chains, such as

C. Gosselin; J. Angeles

1990-01-01

70

Evolution of the one-phonon mixed-symmetry 2{sub 1,ms}{sup +} state in even-even Xe isotopes from inverse-kinematics Coulomb excitation  

SciTech Connect

Coulomb excitation experiments in inverse kinematics on beams of stable {sup 134,132,130,128,126,124}Xe ions impinging on a carbon target at energies of 82% of the respective Coulomb barriers have been performed. The one-phonon 2{sub 1,ms}{sup +} states have been tracked and identified in {sup 134,132,130,128}Xe from the 2{sub i,ms}{sup +}{yields}2{sub 1}{sup +} M1 strength distributions and from 0{sub 1}{sup +}{yields}2{sub i,ms}{sup +} E2 strength distributions responsible for the one-step Coulomb excitation processes. The evolution of the one-phonon 2{sub 1,ms}{sup +} state within the seven even-even stable Xe isotopes is here presented.

Coquard, L.; Pietralla, N.; Leske, J.; Moeller, O.; Moeller, T. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Ahn, T. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); A. W. Wright Nuclear Structure Laboratory, Yale University, New Haven, Connecticut 06520 (United States); Rainovski, G. [Faculty of Physics, St. Kliment Ohridski University of Sofia, 1164 Sofia (Bulgaria); Carpenter, M.; Janssens, R. V. F.; Lister, C. J.; Zhu, S. [Argonne National Laboratory, Argonne, IL 60439 (United States); Bettermann, L.; Rother, W. [Institut fuer Kernphysik, Universitaet Koeln, Zuelpicherstr. 77, 50937 Koeln (Germany)

2009-01-28

71

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

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.

Suzuki, T. [Cyclotron and Radio-isotope Center, Tohoku University, Sendai 980-8578 (Japan); Department of Physics, Tohoku University, Sendai 980-8577 (Japan); Rainovski, G. [St. Kliment Ohridski University of Sofia, Sofia 1164 (Bulgaria); Department of Physics and Astronomy, SUNY, Stony Brook, New York 11794-3800 (United States); Koike, T. [Department of Physics, Tohoku University, Sendai 980-8577 (Japan); Ahn, T.; Costin, A. [Department of Physics and Astronomy, SUNY, Stony Brook, New York 11794-3800 (United States); Carpenter, M. P.; Janssens, R. V. F.; Lister, C. J.; Zhu, S. [Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Danchev, M. [Department of Physics, University of Tennessee Knoxville, Tennessee 37996 (United States); Dewald, A. [Institute fuer Kernphysik der Universitaet zu Koeln, D-50937 Koeln (Germany); Joshi, P.; Wadsworth, R. [Department of Physics, University of York, Heslington YO10 5DD (United Kingdom); Moeller, O. [Institute fuer Kernphysik der Universitaet zu Koeln, D-50937 Koeln (Germany); Institut fuer Kernphysik, TU Darmstadt, D-64689, Darmstadt (Germany); Pietralla, N. [Department of Physics and Astronomy, SUNY, Stony Brook, New York 11794-3800 (United States); Institut fuer Kernphysik, TU Darmstadt, D-64689, Darmstadt (Germany); Shinozuka, T. [Cyclotron and Radio-isotope Center, Tohoku University, Sendai 980-8578 (Japan); Timar, J. [Institute of Nuclear Research (ATOMKI), Pf. 51, 4001 Debrecen (Hungary); Vaman, C. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States)

2008-09-15

72

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

SciTech Connect

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

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

1997-01-01

73

An Inverse Method to Derive the Kinematic History of Rifted Margin Formation Using a New Model of Sea Floor Spreading Initiation  

NASA Astrophysics Data System (ADS)

Recent discoveries of depth-dependent stretching and mantle exhumation at rifted continental margins require new models of margin formation. A two-dimensional coupled fluid mechanics/thermal kinematic model of sea-floor spreading initiation has been developed to predict the deformational and thermal evolution of rifted continental margins through time. The model can also include the effects of pre-breakup pure-shear stretching of continental lithosphere. Rifted margin lithosphere thinning and thermal evolution is dependent on ocean-ridge spreading rate (Vx), the mantle upwelling velocity beneath the ridge axis (Vz), and the pre-breakup lithosphere stretching factor (a). The model predicts the thinning of the upper crust, lower crust and lithospheric mantle of the continental margin, and the history of rifted margin subsidence, water depths and top basement heat-flow. We apply inverse methods to this new forward model of rifted margin formation to explore how successfully model input parameters may be extracted from observational data at rifted margins. The ability of the inverse method to find a unique solution has been established using synthetic data from forward modelling. Output parameters from the inversion are the horizontal and vertical velocities of sea-floor spreading, their variation with time, and the initial pre-breakup lithosphere stretching factor. Initial inversion tests used forward model predictions of the stretching of the upper crust, the whole crust and the whole lithosphere. These model predictions control the variation of crustal thickness and lithosphere temperature beneath the thinned continental margin and adjacent ocean, which in turn control margin subsidence and gravity anomaly. For application of the inversion procedure to observed data on rifted margins, the input data used are measured bathymetry, sediment thickness, gravity anomaly and upper crustal stretching. The forward problem is characterised by a non-linear relationship between parameters and data, and a significant computational burden. We adopt a non-linear minimisation approach implemented through parallel programming on a multi-node computing cluster. We present preliminary results from inversions of observed data measured on 2D profiles for Atlantic continental margins. This work forms part of the NERC Margins iSIMM project. iSIMM investigators are from Cambridge and Liverpool Universities, Schlumberger Cambridge Research and Badley Geoscience, supported by the NERC, the DTI, Agip UK, BP, Amerada Hess Ltd, Anadarko, Conoco, Philips, Shell, Statoil and WesternGeco.

Healy, D.; Kusznir, N.

2004-05-01

74

A First-Estimates Jacobian EKF for Improving SLAM Consistency  

E-print Network

A First-Estimates Jacobian EKF for Improving SLAM Consistency Guoquan P. Huang1 , Anastasios I of EKF-based SLAM from the perspective of observability. We analytically prove that when the Jacobians that of the actual, nonlinear, SLAM system. As a result, the covariance estimates of the EKF undergo reduction

Roumeliotis, Stergios I.

75

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

NASA Astrophysics Data System (ADS)

In this thesis, I summarize the research that I have done at UC Santa Cruz involving my development of joint inversion approaches using hr-GPS, teleseismic body and surface waves, regional seismic, campaign GPS, InSAR and tsunami datasets, to investigate the kinematic rupture patterns of large earthquakes. In eight different studies of rupture models of the 2011 Tohoku earthquake, 2012 Indo-Australia earthquake, 2012 Costa Rica earthquake, 2013 Craig earthquake, 2010 Mentawai earthquake, 2013 Pakistan earthquake, 2010 Chile earthquake and 2014 Iquique earthquake, I adopted each available dataset progressively in my joint inversion algorithm, so that in my current approach I can model all of the types of datasets simultaneously. As noted in this thesis, the teleseismic datasets provide good temporal resolution of the rupture process, while geodetic datasets have good spatial resolution. Tsunami datasets have good spatial resolution of slip near the trench. The joint inversion combines the advantage of each dataset, yielding stable and high- resolution rupture models with detailed spatial and temporal information. Resolving a robust and detailed rupture model helps us to understand co-seismic rupture properties, such as depth dependent energy release patterns, super-shear rupture, and tsunami excitation. Comparing the inter-seismic locking pattern and post-seismic stress release pattern with the co-seismic rupture model helps to investigate the locking and releasing behavior of the fault plane through the earthquake cycle, the stress release level of large earthquakes and the relationship between the main shock ruptures, aftershocks and non-seismogenic deformation.

Yue, Han

76

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

77

Nuclear-matter density distribution in the neutron-rich nuclei 12,14Be from proton elastic scattering in inverse kinematics  

NASA Astrophysics Data System (ADS)

In the present work, the differential cross sections for small-angle proton elastic scattering on the 12,14Be nuclei were measured in inverse kinematics, using secondary radioactive beams with energies near 700 MeV/u produced with the fragment separator FRS at GSI. The main part of the experimental setup was the active target IKAR, which was used simultaneously as a target and a detector for the recoil protons. Auxiliary detectors for projectile tracking and isotope identification completed the setup. The measured differential cross sections were analyzed using the Glauber multiple-scattering theory. For the evaluation of the data several phenomenological nuclear-matter density parametrizations and a sum of Gaussian parametrization were used. The nuclear-matter radii and radial density distributions of the isotopes 12,14Be were deduced. Extended nuclear-matter density distributions were observed in both isotopes, and the halo structure of 14Be was confirmed. The results were also compared with microscopic few-body and fermionic molecular dynamics model calculations concerning the structure of these neutron-rich nuclei.

Ilieva, S.; Aksouh, F.; Alkhazov, G. D.; Chulkov, L.; Dobrovolsky, A. V.; Egelhof, P.; Geissel, H.; Gorska, M.; Inglessi, A.; Kanungo, R.; Khanzadeev, A. V.; Kiselev, O. A.; Korolev, G. A.; Le, X. C.; Litvinov, Yu. A.; Nociforo, C.; Seliverstov, D. M.; Sergeev, L. O.; Simon, H.; Volkov, V. A.; Vorobyov, A. A.; Weick, H.; Yatsoura, V. I.; Zhdanov, A. A.

2012-02-01

78

Measurement of the {sup 1}H({sup 6}He,{sup 6}Li){ital n} reaction in inverse kinematics  

SciTech Connect

The {sup 1}H({sup 6}He,{sup 6}Li){ital n} reaction was studied at 0{degree} with the NSCL A1200 fragment separator in the energy loss mode. A {sup 6}He secondary beam at {ital E}/{ital A}=93 MeV was used to measure the Gamow-Teller and Fermi strengths between the ground state of {sup 6}He and the ground and excited states of {sup 6}Li, in inverse kinematics. At 0{degree} the ground-state cross section is measured to be {ital d}{sigma}{sub {ital GS}}/({ital d}{Omega})=43{plus_minus}16 mb/sr, which is dominated by systematic error in the secondary beam flux. The ratio of Gamow-Teller to Fermi strength is not sensitive to this error and is found to be (87{plus_minus}6){percent} of that expected from ({ital p},{ital n}) systematics and {beta} decay. Angular distributions have been measured between 0{degree} and 10{degree} in the center of mass. {copyright} {ital 1996 The American Physical Society.}

Brown, J.A.; Bazin, D.; Benenson, W.; Caggiano, J.; Fauerbach, M.; Hellstroem, M.; Kelley, J.H.; Kryger, R.A.; Pfaff, R.; Sherrill, B.M.; Steiner, M. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824-1321 (United States)] [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824-1321 (United States); Morrissey, D.J.; Powell, C.F. [National Superconducting Cyclotron Laboratory and Department of Chemistry, Michigan State University, East Lansing, Michigan 48824-1321 (United States)] [National Superconducting Cyclotron Laboratory and Department of Chemistry, Michigan State University, East Lansing, Michigan 48824-1321 (United States)

1996-11-01

79

Kinematic control of redundant robot manipulators: A tutorial  

Microsoft Academic Search

In this paper, we present a tentatively comprehensive tutorial report of the most recent literature on kinematic control of redundant robot manipulators. Our goal is to lend some perspective to the most widely adopted on-line instantaneous control solutions, namely those based on the simple manipulator's Jacobian, those based on the local optimization of objective functions in the null space of

Bruno Siciliano

1990-01-01

80

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

NASA Astrophysics Data System (ADS)

climatic and tectonic processes affect bedrock erosion and exhumation in convergent orogens, but determining their respective influence is difficult. A requisite first step is to quantify long-term (~106 year) erosion rates within an orogen. In the Himalaya, past studies suggest long-term erosion rates varied in space and time along the range front, resulting in numerous tectonic models to explain the observed erosion rate distribution. Here, we invert a large data set of new and existing thermochronological ages to determine both long-term exhumation rates and the kinematics of Neogene tectonic activity in the eastern Himalaya in Bhutan. New data include 31 apatite and five zircon (U-Th)/He ages, and 49 apatite and 16 zircon fission-track ages along two north-south oriented transects across the orogen in western and eastern Bhutan. Data inversion was performed using a modified version of the 3-D thermokinematic model Pecube, with parameter ranges defined by available geochronologic, metamorphic, structural, and geophysical data. Among several important observations, our three main conclusions are as follows: (1) Thermochronologic ages do not spatially correlate with surface traces of major fault zones but appear to reflect the geometry of the underlying Main Himalayan Thrust; (2) our data are compatible with a strong tectonic influence, involving a variably dipping Main Himalayan Thrust geometry and steady state topography; and (3) erosion rates have remained constant in western Bhutan over the last ~10 Ma, while a significant decrease occurred at ~6 Ma in eastern Bhutan, which we partially attribute to convergence partitioning into uplift of the Shillong Plateau.

Coutand, Isabelle; Whipp, David M.; Grujic, Djordje; Bernet, Matthias; Fellin, Maria Giuditta; Bookhagen, Bodo; Landry, Kyle R.; Ghalley, S. K.; Duncan, Chris

2014-02-01

81

Mesh-based inverse kinematics  

Microsoft Academic Search

The ability to position a small subset of mesh vertices and produce a as the problem of finding meaningful mesh deformations that meet specified vertex constraints.Our solution relies on example meshes to indicate the class of meaningful deformations. Each example is represented with a feature vector of deformation gradients that capture the affine transformations which individual triangles undergo relative to

Robert W. Sumner; Matthias Zwicker; Craig Gotsman; Jovan Popovic

2005-01-01

82

Generic robotic kinematic generator for virtual environment interfaces  

NASA Astrophysics Data System (ADS)

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

Flueckiger, Lorenzo; Piguet, Laurent; Baur, Charles

1996-12-01

83

An Efficient, Fully-Implicit, Jacobian-free Time Integration Algorithm for Interfacial Dynamics in Stokes flow  

NASA Astrophysics Data System (ADS)

Interfacial dynamics in Stokes flow is commonly implemented through explicit time integration schemes. While these schemes are rather easy and straightforward to employ, they require that the time step is sufficiently small to ensure stability. To avoid the associated penalty of a large number of time steps required to monitor the deformation of the fluid interface, an implicit time integration algorithm may be used. The commonly used implicit time schemes based on the numerical calculation of the associated Jacobian matrix allow for large time steps but their implementation to realistic problems are prohibited due to the large cost of determining the expensive Jacobian matrix. To overcome this difficulty, we have developed an efficient, fully implicit, Jacobian-free time integration algorithm for interfacial dynamics in Stokes flow. Our method is based on a Jacobian-free integration of the kinematic condition at the interface by employing boundary perturbations between the known interface at some time and the unknown interface at the next time instance. The analysis is similar to that used for determining equilibrium interfaces in Stokes flow with our Newton method. The basic concept of the algorithm is that all the governing equations and boundary conditions on the unknown interface at the next time instance are first transferred to the known interface at the same time, and then related to the known quantities of the previous time. Due to the utilization of much larger time steps, the implicit scheme is much more efficient than the commonly used explicit algorithms and can be used in a wide array of different problems. In the talk, comparisons for two- and three-dimensional interfaces will be presented for both no-stiff and stiff interfacial problems. This work was supported in part by the National Science Foundation (grant CTS-0218770) and by the ACS Petroleum Research Fund. The computations were performed on multiprocessor computers provided by the National Center for Supercomputing Applications (NCSA) in Illinois (grant DMR000003).

Wang, Jingtao; Dimitrakopoulos, Panagiotis

2004-11-01

84

Inversion strategies for visco-acoustic waveform inversion  

NASA Astrophysics Data System (ADS)

Visco-acoustic waveform inversion can potentially yield quantitative images of the distribution of both velocity and the attenuation parameters from seismic data. Intrinsic P-wave attenuation has been of particular interest, but has also proven challenging. Frequency-domain inversion allows attenuation and velocity relations to be easily incorporated, and allows a natural multiscale approach. The Laplace-Fourier approach extends this to allow the natural damping of waveforms to enhance early arrivals. Nevertheless, simultaneous inversion of velocity and attenuation leads to significant `cross-talk' between the resulting images, reflecting a lack of parameter resolution and indicating the need for pre-conditioning and regularization of the inverse problem. We analyse the cross-talk issue by partitioning the inversion parameters into two classes; the velocity parameter class, and the attenuation parameter class. Both parameters are defined at a reference frequency, and a dispersion relation is assumed that describes these parameters at any other frequency. We formulate the model gradients at a forward modelling frequency, and convert them to the reference frequency by employing the Jacobian of the coordinate change represented by the dispersion relation. We show that at a given modelling frequency, the Fréchet derivatives corresponding to these two parameter classes differ only by a 90° phase shift, meaning that the magnitudes of resulting model updates will be unscaled, and will not reflect the expected magnitudes in realistic (Q-1 ? 1) media. Due to the lack of scaling, cross-talk will be enhanced by poor subsurface illumination, by errors in kinematics, and by data noise. To solve these issues, we introduce an attenuation scaling term (the inverse of a penalty term) that is used to pre-condition the gradient by controlling the magnitudes of the updates to the attenuation parameters. Initial results from a suite of synthetic cross-hole tests using a three-layer randomly heterogenous model with both intrinsic and extrinsic (scattering) attenuation demonstrate that cross-talk is a significant problem in attenuation inversion. Using the same model, we further show that cross-talk can be suppressed by varying the attenuation scaling term in our pre-conditioning operator. This strategy is effective for simultaneous inversion of velocity and attenuation, and for sequential inversion (a two-stage approach in which only the velocity models are recovered in the first stage). Further regularization using a smoothing term applied to the attenuation parameters is also effective in reducing cross-talk, which is often highly oscillatory. The sequential inversion approach restricts the search space for attenuation parameters, and appears to be important in retrieving a reliable attenuation model when strong time-damping is applied. In a final test with our synthetic model, we successfully carry out visco-acoustic inversions of noise-contaminated data.

Kamei, R.; Pratt, R. G.

2013-08-01

85

Kinematic analysis of the ARID manipulator  

NASA Technical Reports Server (NTRS)

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

Doty, Keith L

1992-01-01

86

Nonabelian Jacobian of Smooth Projective Surfaces - A Survey  

E-print Network

The nonabelian Jacobian $\\JA$ of a smooth projective surface $X$ is inspired by the classical theory of Jacobian of curves. It is built as a natural scheme interpolating between the Hilbert scheme $\\XD$ of subschemes of length $d$ of $X$ and the stack ${\\bf M}_X (2,L,d)$ of torsion free sheaves of rank 2 on $X$ having the determinant $\\OO_X (L)$ and the second Chern class (= number) $d$. It relates to such influential ideas as variations of Hodge structures, period maps, nonabelian Hodge theory, Homological mirror symmetry, perverse sheave, geometric Langlands program. These relations manifest themselves by the appearance of the following structures on $\\JA$: 1) a sheaf of reductive Lie algebras, 2) (singular) Fano toric varieties whose hyperplane sections are (singular) Calabi-Yau varieties, 3) trivalent graphs. This is an expository paper giving an account of most of the main properties of $\\JA$ uncovered in [R1] and [R2].

Reider, Igor

2011-01-01

87

On the calculation of Jacobian matrices by the Markowitz rule  

SciTech Connect

The evaluation of derivative vectors can be performed with optimal computational complexity by the forward or reverse mode of automatic differentiation. This approach may be applied to evaluate first and higher derivatives of any vector function that is defined as the composition of easily differentiated elementary functions, typically in the form of a computer program. The more general task of efficiently evaluating Jacobians or other derivative matrices leads to a combinational optimization problem, which is conjectured to be NP-hard. Here, we examine this vertex elimination problem and solve it approximately, using a greedy heuristic. Numerical experiments show the resulting Markowitz scheme for Jacobian evaluation to be more efficient than column by column or row by row evaluation using the forward or the reverse mode, respectively.

Griewank, A. [Argonne National Lab., IL (United States); Reese, S. [Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Mathematical Sciences

1991-12-31

88

On the calculation of Jacobian matrices by the Markowitz rule  

SciTech Connect

The evaluation of derivative vectors can be performed with optimal computational complexity by the forward or reverse mode of automatic differentiation. This approach may be applied to evaluate first and higher derivatives of any vector function that is defined as the composition of easily differentiated elementary functions, typically in the form of a computer program. The more general task of efficiently evaluating Jacobians or other derivative matrices leads to a combinational optimization problem, which is conjectured to be NP-hard. Here, we examine this vertex elimination problem and solve it approximately, using a greedy heuristic. Numerical experiments show the resulting Markowitz scheme for Jacobian evaluation to be more efficient than column by column or row by row evaluation using the forward or the reverse mode, respectively.

Griewank, A. (Argonne National Lab., IL (United States)); Reese, S. (Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Mathematical Sciences)

1991-01-01

89

Efficient Computation of the Jacobian for Robot Manipulators  

Microsoft Academic Search

This paper discusses and compares six different methods for calculating the Jacobian for a general N-degree-of-freedom manipulator. We enumerate the computational efficiency of each in terms of the total number of multiplications, addi tions\\/subtractions, and trigonometric functions required as well as in terms of the number of matrix-vector operations needed. We also give the execution times on a PDP-11\\/70 minicomputer

David E. Orin; William W. Schrader

1984-01-01

90

Kinematic analysis of a mobile robot with two-body frames  

Microsoft Academic Search

This paper presents a kind of modeling method for a two-body mobile robot, provides with its kinematic structure parameters and analyzes the forward kinematics and inverse kinematics. Considering the case of surpassing obstacles actively for this two-body mobile robot, the solutions of inverse kinematics are given out based on the geometric approach. Surpassing obstacles and turning analysis are made and

Jingguo Wang; Yangmin Li

2008-01-01

91

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

SciTech Connect

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

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

2013-03-01

92

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

PubMed

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

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

2013-07-01

93

Evaluation of Jacobian determinants by Monte Carlo methods - Application to the quasiclassical approximation in molecular scattering.  

NASA Technical Reports Server (NTRS)

Sampling techniques have been used previously to evaluate Jacobian determinants that occur in classical mechanical descriptions of molecular scattering. These determinants also occur in the quasiclassical approximation. A new technique is described which can be used to evaluate Jacobian determinants which occur in either description. This method is expected to be valuable in the study of reactive scattering using the quasiclassical approximation.

La Budde, R. A.

1972-01-01

94

Statistical Properties of Jacobian Maps and the Realization of Unbiased Large-Deformation Nonlinear Image Registration  

Microsoft Academic Search

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

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

2007-01-01

95

Newton-Raphson power flow solution employing systematically constructed Jacobian matrix  

Microsoft Academic Search

Newton-Raphson power flow method that makes use of the bus admittance matrix remains as an efficient and most popular method to get the power flow solution. Elements of Jacobian matrix are computed from standard expressions, which lack physical significance. In this paper, elements of the Jacobian matrix are obtained considering the power flows in the network elements. Noting that the

Ramiah Jegatheesan; Nursyarizal Mohd Nor; Mohd Fakhizan Romlie

2008-01-01

96

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

SciTech Connect

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

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

2012-06-01

97

Jacobian deformation ellipsoid and Lyapunov stability analysis revisited  

E-print Network

The stability analysis introduced by Lyapunov and extended by Oseledec is an excellent tool to describe the character of nonlinear n-dimensional flows by n global exponents if these flows are stable in time. However, there are two main shortcomings: (a) The local exponents fail to indicate the origin of instability where trajectories start to diverge. Instead, their time evolution contains a much stronger chaos than the trajectories, which is only eliminated by integrating over a long time. Therefore, shorter time intervals cannot be characterized correctly, which would be essential to analyse changes of chaotic character as in transients. (b) Moreover, although Oseledec uses an n dimensional sphere around a point x to be transformed into an n dimensional ellipse in first order, this local ellipse has yet not been evaluated. The aim of this contribution is to eliminate these two shortcomings. Problem (a) disappears if the Oseledec method is replaced by a frame with a 'constraint' as performed by Rateitschak and Klages (RK) [Phys. Rev. E 65 036209 (2002)]. The reasons why this method is better will be illustrated by comparing different systems. In order to analyze shorter time intervals, integrals between consecutive Poincare points will be evaluated. The local problems (b) will be solved analytically by introducing the symmetric 'Jacobian deformation ellipsoid' and its orthogonal submatrix, which enable to search in the full phase space for extreme local separation exponents. These are close to the RK exponents but need no time integration of the RK frame. Finally, four sets of local exponents are compared: Oseledec frame, RK frame, Jacobian deformation ellipsoid and its orthogonal submatrix.

Franz Waldner; Rainer Klages

2010-08-03

98

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

99

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

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

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

2002-01-01

100

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

NASA Astrophysics Data System (ADS)

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

Prejean, Stephanie; Ellsworth, William; Zoback, Mark; Waldhauser, Felix

2002-12-01

101

Analysis of fourth order manipulator kinematics using conic sections  

Microsoft Academic Search

A technique for analyzing robots with fourth-order inverse kinematic solutions is introduced. The solution of the inverse kinematics problem is restated as a pencil of conics. In this representation, the order of the solution reduces when one of the conics in the pencil becomes degenerate and noncentral. Properties of conics are exploited to define and develop special manipulator geometries. The

David R. Smith; Harvey Lipkin

1990-01-01

102

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

SciTech Connect

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

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

2012-06-01

103

State Estimation Observability Based on the Null Space of the Measurement Jacobian Matrix  

Microsoft Academic Search

This letter describes a new technique for state estimation observability analysis. This technique is computationally efficient and based on calculating the null space of the measurement Jacobian matrix. The technique is illustrated through a clarifying example. Conclusions are duly drawn.

E. Castillo; A. J. Conejo; R. E. Pruneda; C. Solares

2005-01-01

104

Kinematic Fanatic  

NSDL National Science Digital Library

In this activity, learners are challenged to design and build a system of gears and kinematics to create a hand-stamping machine. In this activity, learners get a chance to design, build, and test an automated hand-stamping machine by borrowing concepts from existing designs and modifying them to fit their needs. They'll gain experience using gears and pulleys to explore concepts such as mechanical advantage, changing from rotary to linear motion, and altering timing in a machine.

Museum Of Science, Boston

2005-01-01

105

Newton-Raphson State Estimation Solution Employing Systematically Constructed Jacobian Matrix  

Microsoft Academic Search

Newton-Raphson State Estimation method using bus admittance matrix remains as an efficient and most popular method to estimate the state variables. Elements of Jacobian matrix are computed from standard expressions which lack physical significance. In this paper, elements of the state estimation Jacobian matrix are obtained considering the power flow measurements in the network elements. These elements are processed one-by-one

Ramiah Jegatheesan; Perumal Nallagownden

2009-01-01

106

Short loop decompositions of surfaces and the geometry of Jacobians  

E-print Network

Given a Riemannian surface, we consider a naturally embedded graph which captures part of the topology and geometry of the surface. By studying this graph, we obtain results in three different directions. First, we find bounds on the lengths of homologically independent curves on closed Riemannian surfaces. As a consequence, we show that for any $\\lambda \\in (0,1)$ there exists a constant $C_\\lambda$ such that every closed Riemannian surface of genus $g$ whose area is normalized at $4\\pi(g-1)$ has at least $[\\lambda g]$ homologically independent loops of length at most $C_\\lambda \\log(g)$. This result extends Gromov's asymptotic $\\log(g)$ bound on the homological systole of genus $g$ surfaces. We construct hyperbolic surfaces showing that our general result is sharp. We also extend the upper bound obtained by P. Buser and P. Sarnak on the minimal norm of nonzero period lattice vectors of Riemann surfaces %systole of Jacobians of Riemann surfaces in their geometric approach of the Schottky problem to almost $g...

Balacheff, Florent; Sabourau, Stéphane

2010-01-01

107

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

108

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

109

Kinematics of a five degree-of-freedom prosthetic arm  

Microsoft Academic Search

The kinematics of a prosthetic arm consisting of a two-DOF multiloop spatial mechanism and a three-DOF series mechanism is described in this paper. In the beginning, the position analysis is discussed. After that the velocity and acceleration are analyzed. The forward and inverse formulas of velocity and acceleration are deduced using kinematic influence coefficient by means of hypothetic mechanism method

H. B. Wang; T. Ishimatsu; C. Schaerer; Z. Huang

1998-01-01

110

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

E-print Network

We study the Jacobian Poisson structures in any dimension invariant with respect to the discrete Heisenberg group. The classification problem is related to the discrete volume of suitable solids. Particular attention is given to dimension 3 whose simplest example is the Artin-Schelter-Tate Poisson tensors respectively.

Giovanni Ortenzi; Vladimir Rubtsov; Serge Roméo Tagne Pelap

2011-03-22

111

Estimating the Jacobian of the Singular Value Decomposition: Theory and Applications  

Microsoft Academic Search

The Singular Value Decomposition (SVD) of a matrix is a linear algebra tool that has been successfully applied to a wide variety of domains. The present paper is concerned with the problem of estima- ting the Jacobian of the SVD components of a matrix with respect to the matrix itself. An exact analytic technique is developed that facili- tates the

Théodore Papadopoulo; Manolis I. A. Lourakis

2000-01-01

112

Several Parallel Algorithms for Solving Nonlinear Systems with Symmetric and Positive Definite Jacobians  

Microsoft Academic Search

In this work we describe two sequential algorithms and their parallel counterparts for solving nonlinear systems, when the Jacobian matrix is symmetric and positive definite. This case appears frequently in unconstrained optimization problems. Both algorithms are based on Newton's method. The first solves the inner iteration with Cholesky decomposition while the second is based on the inexact Newton methods family,

Jesús Peinado; Antonio M. Vidal

2003-01-01

113

Online estimation of Image Jacobian Matrix for uncalibrated dynamic hand-eye coordination  

Microsoft Academic Search

This paper focuses on three different strategies for online estimation of the Image Jacobian Matrix (IJM) in uncalibrated robotic visual servoing, with the help of different scenarios of system configurations and coordination tasks that are prevalent in current research. The least square estimation method and the constant IJM policy are proposed for monocular visual feedback, while a Kalman filter-based method

Jianbo Su; Yanjun Zhang; Zhiwei Luo

2008-01-01

114

A new training and pruning algorithm based on node dependence and Jacobian rank deficiency  

Microsoft Academic Search

In this paper, a new subset-based training and pruning (SBTP) algorithm is proposed based on the relationship between node dependence and Jacobian rank deficiency. At each training iteration, the orthogonal factorization with column permutation is applied to the output of the nodes in the same hidden layer to identify the dependent nodes. The output weights of the dependent nodes will

Jinhua Xu; Daniel W. C. Ho

2006-01-01

115

Radiance and Jacobian intercomparison of radiative transfer models applied to HIRS and AMSU channels  

E-print Network

applications, notably the assimila- tion of satellite radiances in near real time, fast and accurate forwardRadiance and Jacobian intercomparison of radiative transfer models applied to HIRS and AMSU fast radiative transfer models (RTMs) and line-by-line (LBL) models. The intercomparison focuses

Pardo-Carrión, Juan R.

116

Joint three-dimensional inversion of coupled groundwater flow and heat transfer based on automatic differentiation: sensitivity calculation, verification, and synthetic examples  

Microsoft Academic Search

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

V. Rath; A. Wolf; H. M. Bücker

2006-01-01

117

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

Microsoft Academic Search

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

P. Staroverov; M. Arbulu; C. Balaguer

118

Principal Component Geostatistical Approach for large-dimensional inverse problems  

NASA Astrophysics Data System (ADS)

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

Kitanidis, P. K.; Lee, J.

2014-07-01

119

Hutchinson-Weber involutions degenerate exactly when the Jacobian is Comessatti  

E-print Network

We consider the Jacobian Kummer surface $X$ of a genus two curve $C$. We prove that the Hutchinson-Weber involution on $X$ degenerates if and only if the Jacobian $J(C)$ is Comessatti. Also we give several conditions equivalent to this, which include the classical theorem of Humbert. The key notion is the Weber hexad. We include explanation of them and discuss the dependence between the conditions of main theorem for various Weber hexads. It results in "the equivalence as dual six". We also give a detailed description of relevant moduli spaces. As an application, we give a conceptual proof of the computation of the patching subgroup for generic Hutchinson-Weber involutions.

Ohashi, Hisanori

2010-01-01

120

A variable-stepsize Jacobian-free exponential integrator for simulating transport in heterogeneous porous media: Application to wood drying  

NASA Astrophysics Data System (ADS)

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

Carr, E. J.; Turner, I. W.; Perré, P.

2013-01-01

121

Image-Based Robust Control of Robot Manipulators Under Jacobian Uncertainty  

Microsoft Academic Search

In this paper, an image-based robust controller for tracking control of robot manipulators using a single camera is proposed.\\u000a The proposed controller has robustness to parametric uncertainties of the robot manipulator and compensation for uncertainties\\u000a included in the image Jacobian. The stability of the closed-loop system is proved by Lyapunov approach. The performance of\\u000a the proposed method is demonstrated by

Chin Su Kim; Eun Jong Mo; Min Seok Jie; Soo Chan Hwang; Kang Woong Lee

2007-01-01

122

Image-based robust control of robot manipulators with image Jacobian and dynamics uncertainties  

Microsoft Academic Search

In this paper, we design an image-based robust controller to compensate uncertainties with image Jacobian and robot dynamics due to uncertain depth measurement and load variations. The proposed controller with eye-in-hand structure has separate terms to compensate each of uncertainties. The ultimately uniform boundedness of the closed-loop system is proved by the Lyapunov method. The performance of the proposed control

Chin-Su Kim; Eun-Jong Mo; Sung-Min Han; Min-Seok Jie; Kang-Woong Lee

2008-01-01

123

Bulletin of the Seismological Society of America, Vol. 96, No. 4B, pp. S143S158, September 2006, doi: 10.1785/0120050826 Kinematic Inversion of the 2004 M 6.0 Parkfield Earthquake Including  

E-print Network

of coseismic slip on the fault. To reduce noise in the inversion, we take into account local amplifications. The study of earthquake physics is constrained by the inability to measure coseismic slip everywhere to the surface--site effects. Isolating the desired rupture infor- mation in the seismic records is a nontrivial

Archuleta, Ralph

124

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

NASA Astrophysics Data System (ADS)

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

Andersen, David R.; Bershady, Matthew A.

2013-05-01

125

Real time markerless motion tracking using linked kinematic chains  

DOEpatents

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

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

2007-08-14

126

Regularity of mappings inverse to Sobolev mappings  

SciTech Connect

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

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

2012-10-31

127

Inverse Functions  

NSDL National Science Digital Library

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

Smith, David; Moore, Lawrence

2001-01-25

128

Magnetotelluric Inversion in a 2D Anisotropic Environment  

NASA Astrophysics Data System (ADS)

In recent years several authors have proposed algorithms to perform magnetotelluric (MT) inversion in a 3D environment. The development of high performance computer (hpc) machines allows the solution of these inverse problems in a reasonable time, nevertheless the solution of a 3D problem remains at the present extremely challenging. Moreover it is proofed that any magnitude of anisotropy possibly present in the subsurface conductivity can be modeled by a sufficient dense discretization of a 3D isotropic domain, keeping the recognition of intrinsically anisotropic bulks virtually impossible for a 3D code. These arguments convinced us to develop a 2D inverse code able in assessing anisotropy and running in an affordable time, testing several scenario for the same dataset in the same time in which a 3D inversion code produces its first model. In this work we report results from synthetic tests we performed. MT inverse problem is challenging because of several reasons. It is both highly non-linear, ill-conditioned and suffers of a severe non-uniqueness of the solution, therefore we developed an inversion algorithm based on the classic Levenberg-Marquardt (LM) strategy, minimizing the objective function (?-G-(m)-d)2 ?(m )= ? +?aLa +?sLs in which m is the model, G the forward operator, d the data vector, L* the regularization matrix and ?* the trade-off parameter for respectively anisotropy and structure. Usually LM method is used for medium size problems, mainly because it requires the explicit computation and storage of the Jacobian matrix J and the explicit knowledge of the product JTJ. To compute the Jacobian it has proofed that the electrical reciprocity theorem is a valuable tool, allowing to compute the full Jacobian with the evaluation of one forward problem per station in spite of one forward problem per parameter as usually done with the finite-difference method. Moreover the computation of the forward response can be easily performed in parallel, due the mutual independency of the different spectral components, storing the Jacobian in a distribute machine memory and solving at the same time the problem of the huge memory requirements used to store the product JTJ and speeding up the whole process. We performed tests on the simple synthetic model released with the code from Pek and Santos [2004]: an 84-100 cells grid, grouped in 3 up to 20 blocks sharing the same conductivities. Results proof the capacity of the algorithm in recovering the subsurface structure with good precision, reaching an RMS of the magnitude 10-5 for the 20 block case without the use of regularization. More tests will be presented and results highlighted.

Mandolesi, E.; Jones, A. G.

2012-04-01

129

Constructing with movement: kinematics  

Microsoft Academic Search

This paper describes Kinematics: a novel construction toy for children consisting of both active (shape-changing or rotating) and passive building blocks. In comparison to similar systems, the active components of Kinematics do not require programming or recording. This allows children to focus on reassembly and direct observation of the resulting movement from simple changes made to a constructed structure. The

Leonhard Oschuetz; Daniel Wessolek; Wolfgang Sattler

2010-01-01

130

Kinematics Graph Interpretation Project  

NSDL National Science Digital Library

The primary goal of the Kinematics Graphing Project is to investigate the ability of students to interpret kinematics graphs and to generate a set of suggestions for faculty teaching the subject. Evaluation instruments are used to uncover the common misconceptions of students.

Beichner, Robert J.

2003-10-10

131

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

SciTech Connect

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

Dana Knoll; HyeongKae Park; Chris Newman

2011-02-01

132

Compactified Strings as Quantum Statistical Partition Function on the Jacobian Torus  

SciTech Connect

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

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

2006-12-31

133

Appendix 1 Stability We calculate the Jacobian matrix Dfw, for a fixed vector w  

E-print Network

= I + C - 2w(Cw)T - (wT Cw)I Proof. Call g(w) = (wT Cw)w , so f(w) = w + (Cw - g(w)) gi(w) = (wT CwAppendix 1 ­ Stability We calculate the Jacobian matrix Dfw, for a fixed vector w: Lemma 0.1. Dfw)wi If i = j: gi wj (w) = wj ( k,l Cklwkwl)wi = 2( k Ckjwk)wi = 2[Cw]jwi If i = j: gi wi (w) = wi ( k

Adams, Paul R.

134

Employment of Jacobian elliptic functions for solving problems in nonlinear dynamics of microtubules  

NASA Astrophysics Data System (ADS)

We show how Jacobian elliptic functions (JEFs) can be used to solve ordinary differential equations (ODEs) describing the nonlinear dynamics of microtubules (MTs). We demonstrate that only one of the JEFs can be used while the remaining two do not represent the solutions of the crucial differential equation. We show that a kink-type soliton moves along MTs. Besides this solution, we also discuss a few more solutions that may or may not have physical meanings. Finally, we show what kind of ODE can be solved by using JEFs.

Slobodan, Zekovi?; Annamalai, Muniyappan; Slobodan, Zdravkovi?; Louis, Kavitha

2014-02-01

135

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

E-print Network

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

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

2014-01-01

136

Analysis of a Swashplate Mechanism of the Hingeless Rotor Hub with the Flybar in a Model Helicopter, Part I: Kinematics  

NASA Astrophysics Data System (ADS)

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

Sabaapour, Mohammad Reza; Zohoor, Hassan

137

Inverse Functions  

NSDL National Science Digital Library

Created by Lang Moore and David Smith for the Connected Curriculum Project, this is a module to review concepts of inverse functions, and to use those concepts, together with functions defined by integrals, to develop inverse trigonometric functions. This is one within a much larger set of learning modules hosted by Duke University.

Moore, Lang; Smith, David

2010-05-05

138

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

SciTech Connect

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

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

1992-08-01

139

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

SciTech Connect

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

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

1992-01-01

140

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

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

141

A fully implicit Newton-Krylov-Schwarz method for tokamak magnetohydrodynamics: Jacobian construction and preconditioner formulation  

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

142

Learning Flexible Full Body Kinematics for Humanoid Tool Use  

Microsoft Academic Search

We show that inverse kinematics of different tools can be efficiently learned with a single recurrent neural network. Our model exploits all upper body degrees of freedom of the Honda's humanoid robot research platform. Both hands are controlled at the same time with parametrized tool geometry. We show that generalization both in space as well as across tools is possible

Matthias Rolf; Jochen J. Steil; Michael Gienger

2010-01-01

143

An optimal resolved rate law for kinematically redundant manipulators  

NASA Technical Reports Server (NTRS)

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

Bourgeois, B. J.

1987-01-01

144

Kinematic Self-Similarity  

E-print Network

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

A. A. Coley

1996-10-25

145

Three tooth kinematic coupling  

DOEpatents

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

Hale, Layton C. (Livermore, CA)

2000-01-01

146

Kinematics of deformable media  

E-print Network

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

Anirvan Dasgupta; Hemwati Nandan; Sayan Kar

2007-09-05

147

Kinematics of an infinitely flexible robot arm  

NASA Astrophysics Data System (ADS)

An effort is made to define a command-and-control algorithm for a flexible robot arm design which maximizes flexibility through its large number of degrees-of-freedom, in the manner of a 'tentacle'. Algorithms including both forward and inverse kinematics are developed for commanding smooth arm motions in the presence of obstacles, on the basis of Catmull-Rom splines and local radius-of-curvature commands to discrete actuators along the length of the arm. Sample trajectories are examined, and a spline-curve algorithm is successfully applied for this arm configuration; the accuracy and collision-avoidance of the arm are verified by means of a simulation.

Choi, P. J.; Rice, J. A.; Cesarone, J. C.

1993-06-01

148

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

SciTech Connect

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

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

2013-05-01

149

Jacobian code generated by source transformation and vertex elimination can be as efficient as hand-coding  

Microsoft Academic Search

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

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

2004-01-01

150

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

E-print Network

Dynamic inversion of the 2000 Tottori earthquake based on elliptical subfault approximations Sara nonlinear method for the kinematic and dynamic inversion of nearfield strong motion data at low frequencies apply this method to the dynamic inversion of the Western Tottori (Japan) earthquake (Mw 6.6­6.8) of 6

Madariaga, Raúl

151

Parallel Jacobian-free Newton Krylov solution of the discrete ordinates method with flux limiters for 3D radiative transfer  

NASA Astrophysics Data System (ADS)

The present study introduces a parallel Jacobian-free Newton Krylov (JFNK) general minimal residual (GMRES) solution for the discretized radiative transfer equation (RTE) in 3D, absorbing, emitting and scattering media. For the angular and spatial discretization of the RTE, the discrete ordinates method (DOM) and the finite volume method (FVM) including flux limiters are employed, respectively. Instead of forming and storing a large Jacobian matrix, JFNK methods allow for large memory savings as the required Jacobian-vector products are rather approximated by semiexact and numerical formulations, for which convergence and computational times are presented. Parallelization of the GMRES solution is introduced in a combined memory-shared/memory-distributed formulation that takes advantage of the fact that only large vector arrays remain in the JFNK process. Results are presented for 3D test cases including a simple homogeneous, isotropic medium and a more complex non-homogeneous, non-isothermal, absorbing-emitting and anisotropic scattering medium with collimated intensities. Additionally, convergence and stability of Gram-Schmidt and Householder orthogonalizations for the Arnoldi process in the parallel GMRES algorithms are discussed and analyzed. Overall, the introduction of JFNK methods results in a parallel, yet scalable to the tested 2048 processors, and memory affordable solution to 3D radiative transfer problems without compromising the accuracy and convergence of a Newton-like solution.

Godoy, William F.; Liu, Xu

2012-06-01

152

RESEARCH ARTICLE Freeing the serial mechanism designer from inverse kinematic  

E-print Network

chose to weigh other factors, such as actuator size and patient safety, more heavily than the ability of robots in surgery has slowly gained popularity. With systems present in hospitals around the world of one side of the operating table, and a large portion of the area above the patient. Several research

Rosen, Jacob

153

Inverse Kinodynamics: Editing and Constraining Kinematic Approximations of Dynamic Motion  

E-print Network

Rahgoshay1 Amir Rabbani1 Karan Singh2 Paul G. Kry1 1 School of Computer Science, Centre for Intelligent Machines, McGill University 2 Department of Computer Science, University of Toronto ABSTRACT We present anima- tion software. Overlaid dynamics, unfortunately compromise the second and third reasons animators

Kry, Paul

154

EFFICIENT INVERSE KINEMATICS ALGORITHM BASED ON CONFORMAL GEOMETRIC ALGEBRA  

E-print Network

entity standard repr. direct repr. Point P = x+ 1 2 x2e +e0 Sphere s = P- 1 2 r2e s = x1 x2 x3 x4 Plane = n+de = x1 x2 x3 e Circle z = s1 s2 z = x1 x2 x3 Line l = 1 1 l = x1 x2 e Point Pair Pp = s1 s2 s3 P

155

Measurements of neutron-induced reactions in inverse kinematics  

E-print Network

Neutron capture cross sections of unstable isotopes are important for neutron induced nucleosynthesis as well as for technological applications. A combination of a radioactive beam facility, an ion storage ring and a high flux reactor would allow a direct measurement of neutron induced reactions over a wide energy range on isotopes with half lives down to minutes.

René Reifarth; Yuri A. Litvinov

2013-12-13

156

A Geometrical Approach to Inverse Kinematics for Continuum Manipulators  

E-print Network

A. Csencsits, Student member, IEEE, Bryan A. Jones, Member, IEEE, and Ian Walker, Fellow, IEEE extensively studied, and surveys of many of the fundamental results for conventional (rigid-link based a key motivation for continuum robots, enabling them to maneuver in congested environments [19

157

AN INVERSE KINEMATIC MATHEMATICAL MODEL USING GROEBNER BASIS THEORY FOR  

E-print Network

and Research Air Force Institute of Technology Wright Patterson Air Force Base, Ohio 2 3D Human Signatures OF MINNESOTA 400 Lind Hall 207 Church Street S.E. Minneapolis, Minnesota 55455­0436 Phone: 612-624-6066 Fax is to present a new approach for the application of Groebner Basis Theory in the development of an upper

158

Development of a high-speed 3-axis machine tool using a novel parallel-kinematics X-Y table  

Microsoft Academic Search

In this paper we discuss the development and performance evaluation of a high-speed, 3-axis milling machine using a novel parallel kinematics x-y table. The x-y table is based on a an inversion of the Oldham coupling. The advantages of this kinematic configuration include low inertia, uniform kinematic conditioning, and dynamically matched axes. The design of the x-y table makes this

J Dong; C Yuan; J. A Stori; P. M Ferreira

2004-01-01

159

Indirect inversions  

NASA Astrophysics Data System (ADS)

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.

Sergienko, Olga

2013-04-01

160

Inverse problem of capillary filling.  

PubMed

The inverse problem of capillary filling, as defined in this work, consists in determining the capillary radius profile from experimental data of the meniscus position l as a function of time t. This problem is central in diverse applications, such as the characterization of nanopore arrays or the design of passive transport in microfluidics; it is mathematically ill posed and has multiple solutions; i.e., capillaries with different geometries may produce the same imbibition kinematics. Here a suitable approach is proposed to solve this problem, which is based on measuring the imbibition kinematics in both tube directions. Capillary filling experiments to validate the calculation were made in a wide range of length scales: glass capillaries with a radius of around 150???m and anodized alumina membranes with a pores radius of around 30??nm were used. The proposed method was successful in identifying the radius profile in both systems. Fundamental aspects also emerge in this study, notably the fact that the l(t)?t1/2 kinematics (Lucas-Washburn relation) is not exclusive of uniform cross-sectional capillaries. PMID:24745427

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

2014-04-01

161

Inverse Problem of Capillary Filling  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

162

Parallel Kinematic Machines (PKM)  

SciTech Connect

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.

Henry, R.S.

2000-03-17

163

Organ of Corti kinematics.  

PubMed

The internal workings of the organ of Corti and their relation to basilar membrane motion are examined with the aid of a simple kinematic model. It is shown that, due to the lever system embodied in the organ of Corti, there is a significant transformer gain between basilar membrane and cilia displacements. While this transformation is nonlinear, linear response prevails in the narrow physiologically relevant operating range of the ciliary transducer. The model also simulates cilia deflection when the mechanical stimulus is the length change of outer hair cells. PMID:14690059

Dallos, Peter

2003-09-01

164

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

NASA Astrophysics Data System (ADS)

Conventional methods of interpreting seismic data rely on filtering and processing limited portions of the recorded wavefield. Typically, either reflections, refractions or surface waves are considered in isolation. Particularly in near-surface engineering and environmental investigations (depths less than, say 100 m), these wave types often overlap in time and are difficult to separate. Full waveform inversion is a technique that seeks to exploit and interpret the full information content of the seismic records without the need for separating events first; it yields models of the subsurface at sub-wavelength resolution. We use a finite element modelling code to solve the 2D elastic isotropic wave equation in the frequency domain. This code is part of a Gauss-Newton inversion scheme which we employ to invert for the P- and S-wave velocities as well as for density in the subsurface. For shallow surface data the use of an elastic forward solver is essential because surface waves often dominate the seismograms. This leads to high sensitivities (partial derivatives contained in the Jacobian matrix of the Gauss-Newton inversion scheme) and thus large model updates close to the surface. Reflections from deeper structures may also include useful information, but the large sensitivities of the surface waves often preclude this information from being fully exploited. We have developed two methods that balance the sensitivity distributions and thus may help resolve the deeper structures. The first method includes equilibrating the columns of the Jacobian matrix prior to every inversion step by multiplying them with individual scaling factors. This is expected to also balance the model updates throughout the entire subsurface model. It can be shown that this procedure is mathematically equivalent to balancing the regularization weights of the individual model parameters. A proper choice of the scaling factors required to balance the Jacobian matrix is critical. We decided to normalise the columns of the Jacobian based on their absolute column sum, but defining an upper threshold for the scaling factors. This avoids particularly small and therefore insignificant sensitivities being over-boosted, which would produce unstable results. The second method proposed includes adjusting the inversion cell size with depth. Multiple cells of the forward modelling grid are merged to form larger inversion cells (typical ratios between forward and inversion cells are in the order of 1:100). The irregular inversion grid is adapted to the expected resolution power of full waveform inversion. Besides stabilizing the inversion, this approach also reduces the number of model parameters to be recovered. Consequently, the computational costs and the memory consumption are reduced significantly. This is particularly critical when Gauss-Newton type inversion schemes are employed. Extensive tests with synthetic data demonstrated that both methods stabilise the inversion and improve the inversion results. The two methods have some redundancy, which can be seen when both are applied simultaneously, that is, when scaling of the Jacobian matrix is applied to an irregular inversion grid. The calculated scaling factors are quite balanced and span a much smaller range than in the case of a regular inversion grid.

Nuber, André; Manukyan, Edgar; Maurer, Hansruedi

2014-05-01

165

Design of a generic five-axis postprocessor based on generalized kinematics model of machine tool  

Microsoft Academic Search

This paper presents a generic five-axis postprocessor system for various five-axis machine tools. The generalized kinematics model of common five-axis machines is constructed by combining two rotational degrees of freedom on the fixture table and two rotational degrees of freedom on the spindle. The complete analytical equations for NC data are obtained through homogeneous coordinate transformation matrix and inverse kinematics.

Chen-Hua She; Chun-Cheng Chang

2007-01-01

166

Inverse Functions  

NSDL National Science Digital Library

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

167

Kinematics for multisection continuum robots  

Microsoft Academic Search

We introduce a new method for synthesizing kinematic relationships for a general class of continuous backbone, or continuum , robots. The resulting kinematics enable real-time task and shape control by relating workspace (Cartesian) coordinates to actuator inputs, such as tendon lengths or pneumatic pressures, via robot shape coordinates. This novel approach, which carefully considers physical manipulator constraints, avoids artifacts of

Bryan A. Jones; Ian D. Walker

2006-01-01

168

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

NASA Astrophysics Data System (ADS)

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

Mehl, S.

2012-12-01

169

Kinematics of vector fields  

E-print Network

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

S. Manoff

2000-03-02

170

Uncertainty Quantification in Earthquake Source Inversions: The Source Inversion Validation (SIV) Project  

NASA Astrophysics Data System (ADS)

Finite-fault source inversions estimate kinematic rupture parameters of earthquakes using a variety of available data sets and inversion approaches. Rupture models are obtained by solving an inherently ill-posed inverse problem, subject to numerous a priori assumptions, noisy observations, and imperfect Green's functions. Despite these limitations, near real-time source inversions are becoming increasingly popular, while we still face the dilemma that uncertainties in source inversions are essentially unknown. Yet, the accurate estimation of earthquake rupture properties, including proper uncertainty quantification, is critically important for earthquake seismology and seismic hazard analysis, as they help to adequately characterize earthquake complexity across all scales. The collaborative project "Source Inversion Validation" (SIV) attempts to quantify the intra-event variability in rupture models (evidenced in the SRCMOD database, http://equake-rc.info/srcmod), and to propose robust uncertainty metrics for earthquake source inversions. The SIV efforts include a rigorous testing platform to examine the current state-of-the-art in earthquake source inversion, and to develop and test novel source inversion approaches. In this presentation, we will summarize initial SIV results related to previous benchmark exercises, discuss the latest findings for a test case of a complex rupture embedded in a 3D heterogeneous Earth model, and propose metrics to quantify rupture-model variability, quality of data fitting, and model robustness.

Mai, P. Martin

2013-04-01

171

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

SciTech Connect

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

Gary D. Egbert

2007-03-22

172

Multivariate statistics of the Jacobian matrices in tensor based morphometry and their application to HIV/AIDS.  

PubMed

Tensor-based morphometry (TBM) is widely used in computational anatomy as a means to understand shape variation between structural brain images. A 3D nonlinear registration technique is typically used to align all brain images to a common neuroanatomical template, and the deformation fields are analyzed statistically to identify group differences in anatomy. However, the differences are usually computed solely from the determinants of the Jacobian matrices that are associated with the deformation fields computed by the registration procedure. Thus, much of the information contained within those matrices gets thrown out in the process. Only the magnitude of the expansions or contractions is examined, while the anisotropy and directional components of the changes are ignored. Here we remedy this problem by computing multivariate shape change statistics using the strain matrices. As the latter do not form a vector space, means and covariances are computed on the manifold of positive-definite matrices to which they belong. We study the brain morphology of 26 HIV/AIDS patients and 14 matched healthy control subjects using our method. The images are registered using a high-dimensional 3D fluid registration algorithm, which optimizes the Jensen-Rényi divergence, an information-theoretic measure of image correspondence. The anisotropy of the deformation is then computed. We apply a manifold version of Hotelling's T2 test to the strain matrices. Our results complement those found from the determinants of the Jacobians alone and provide greater power in detecting group differences in brain structure. PMID:17354890

Lepore, Natasha; Brun, Caroline A; Chiang, Ming-Chang; Chou, Yi-Yu; Dutton, Rebecca A; Hayashi, Kiralee M; Lopez, Oscar L; Aizenstein, Howard J; Toga, Arthur W; Becker, James T; Thompson, Paul M

2006-01-01

173

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

SciTech Connect

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

Dana A. Knoll; H. Park; Kord Smith

2011-02-01

174

Adaptive Inverse Control of an OmniDirectional Mobile Robot  

Microsoft Academic Search

\\u000a The omni-directional mobile robot developed by Shanghai Jiaotong University was introduced. The inverse kinematics and dynamics\\u000a of the robot were modeled for decoupled control simulation. An adaptive inverse control (AIC) scheme incorporating Dynamic\\u000a neural network (DNN) controller and conventional feedback controller was presented. Finally, linear and circular trajectories\\u000a following simulation results demonstrate that the AIC can decouple the dynamic control

Yuming Zhang; Qixin Cao; Shouhong Miao

2005-01-01

175

Why Teach Kinematics?  

NASA Astrophysics Data System (ADS)

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

Dykstra, Dewey

2002-05-01

176

Kinematic precision of gear trains  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

177

Kinetics of hula hooping: An inverse dynamics analysis  

Microsoft Academic Search

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

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

2008-01-01

178

HI in spiral galaxies Stellar kinematics  

E-print Network

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

Kruit, Piet van der

179

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

NASA Technical Reports Server (NTRS)

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

Gretz, Bruce; Tilley, Scott W.

1989-01-01

180

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

NASA Astrophysics Data System (ADS)

In this paper, error modeling and analysis of a typical 3-degree of freedom translational Parallel Kinematic Machine is presented. This mechanism provides translational motion along the Cartesian X-, Y- and Z-axes. It consists of three limbs each having an arm and forearm with prismatic-revolute-revolute-revolute joints. The moving or tool platform maintains same orientation in the entire workspace due to its joint arrangement. From inverse kinematics, the joint angles for a given position of tool platform necessary for the error modeling and analysis are obtained. Error modeling is done based on the differentiation of the inverse kinematic equations. Variation of pose errors along X, Y and Z directions for a set of dimensions of the parallel kinematic machine is presented. A non-dimensional performance index, namely, global error transformation index is used to study the influence of dimensions and its corresponding global maximum pose error is reported. An attempt is made to find the optimal dimensions of the Parallel Kinematic Machine using Genetic Algorithms in MATLAB. The methodology presented and the results obtained are useful for predicting the performance capability of the Parallel Kinematic Machine under study.

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

2014-06-01

181

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

NASA Astrophysics Data System (ADS)

Two-phase flow in porous media occurs in various settings, such as the sequestration of CO2 in the subsurface, radioactive waste management, the flow of oil or gas in hydrocarbon reservoirs, or groundwater remediation. To model the sequestration of CO2, we consider a fully coupled formulation of the system of nonlinear, partial differential equations. For the solution of this system, we employ the Box method after Huber & Helmig (2000) for the space discretization and the fully implicit Euler method for the time discretization. After linearization with Newton's method, it remains to solve a linear system in every Newton step. We compare different iterative methods (BiCGStab, GMRES, AGMG, c.f., [Notay (2012)]) combined with different preconditioners (ILU0, ASM, Jacobi, and AMG as preconditioner) for the solution of these systems. The required Jacobians can be obtained elegantly with automatic differentiation (AD) [Griewank & Walther (2008)], a source code transformation providing exact derivatives. We compare the performance of the different iterative methods with their respective preconditioners for these linear systems. Furthermore, we analyze linear systems obtained by approximating the Jacobian with finite differences in terms of Newton steps per time step, steps of the iterative solvers and the overall solution time. Finally, we study the influence of heterogeneities in permeability and porosity on the performance of the iterative solvers and their robustness in this respect. References [Griewank & Walther(2008)] Griewank, A. & Walther, A., 2008. Evaluating Derivatives: Principles and Techniques of Algorithmic Differentiation, SIAM, Philadelphia, PA, 2nd edn. [Huber & Helmig(2000)] Huber, R. & Helmig, R., 2000. Node-centered finite volume discretizations for the numerical simulation of multiphase flow in heterogeneous porous media, Computational Geosciences, 4, 141-164. [Notay(2012)] Notay, Y., 2012. Aggregation-based algebraic multigrid for convection-diffusion equations, SIAM Journal on Scientific Computing, 34, A2288-A2316.

Büsing, Henrik

2013-04-01

182

Paracentric inversions: a review  

Microsoft Academic Search

This review of paracentric inversions in man includes what we know of the behaviour and reproductive consequences of paracentric inversions from other species. Observations of naturally occurring inversions in several species of plants and animals and results of experiments with mutagenically induced inversions in the mouse are discussed. From a review of 184 cases, it is concluded that most of

K. Madan

1995-01-01

183

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

Microsoft Academic Search

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

Marc Arsenault; Clément M. Gosselin

2006-01-01

184

Dynamic modeling and robust control of a 3-PRC translational parallel kinematic machine  

E-print Network

Dynamic modeling and robust control of a 3-PRC translational parallel kinematic machine Yangmin Li robots Inverse dynamics Robust control Tracking control a b s t r a c t The dynamic modeling and robust, the simplified dynamic equations have been derived via the virtual work principle and validated on a virtual

Li, Yangmin

185

Deformation field validation and inversion applied to adaptive radiation therapy  

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

186

KINEMATIC ANALYSIS OF MODULAR, TRUSS-BASED MANIPULATOR UNITS  

SciTech Connect

Decontamination and Dismantling (D&D) activities within the U.S. Department of Energy (DOE) require a long reach manipulator with a large load capacity. Variable Geometry Trusses (VGTs) are a unique class of mechanical structures which allow the advantages of truss structures for large scale applications to be applied to large robotic manipulators. Individual VGT units may be assembled to create a modular, long-reach, truss-type manipulator. Each module of such a manipulator system is either a static truss section or one of several possible VGT geometries. While many potential applications exist for this technology, the present work is largely motivated by the need for generic robotic systems for remote manipulation. A manipulator system based on VGT modules provides several advantages. The reconfigurable nature of the manipulator system allows it to be adapted on site to unforeseen conditions. The kinematic redundancy of the manipulator enables it to work effectively even in a highly obstructed workspace. The parallel structure of the truss modules enables the manipulator to be withdrawn in the event of a structural failure. Finally, the open framework of the modules provides a clear, protected passageway for control and power cabling, waste conveyance, or other services required at the end effector. As is implied in a truss structure, all primary members of a VGT are ideally loaded in pure tension or compression. This results in an extremely stiff and strong manipulator system with minimal overall weight. Careful design of the joints of a VGT is very important to the overall stiffness and accuracy of the structure, as several links (as many as six) are joined together at each joint. The greatest disadvantage to this approach to manipulator design has traditionally been that the kinematics of VGT structures are complex and poorly understood. This report specifically addresses the kinematics of several possible geometries for the individual VGT units. Equations and solution techniques are developed for solving the "forward" or "direct" and "inverse" kinematic problems for these geometries. The" forward" kinematic problem is that of finding the position and orientation of the distal end of the VGT relative to the proximal end, given the specific displacements of the (linear) actuators. This problem is rarely solvable in closed form. However, powerful iterative algorithms capable of solution in real time on typical modern robot control hardware are presented. The "inverse" kinematic problem is that of finding the required actuator displacements given the position and orientation of the distal end of the VGT relative to the proximal end. For specific VGT geometries, closed-form solutions are presented. For the more general problem, iterative algorithms capable of solution in real time are again derived and presented.

Salerno, R. J.

1994-06-01

187

Kinematic sensitivity of robot manipulators  

NASA Technical Reports Server (NTRS)

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

Vuskovic, Marko I.

1989-01-01

188

Lava flows as kinematic waves  

NASA Technical Reports Server (NTRS)

A recently proposed model for the emplacement of lava flows is reinterpreted as a kinematic wave theory for the depth of the flow. Explicit kinematic wave solutions and their properties are derived for three time-dependent boundary conditions of practical interest. These boundary conditions correspond to effusion rates that decrease, increase, and crest and broadly reflect types of eruption behavior documented in the geologic literature. Particular attention is given to the way source behavior propagates along the flow in relation to the advance of the flow itself.

Baloga, Stephen

1987-01-01

189

Kinematic performance analysis of a parallel-chain hexapod machine  

SciTech Connect

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

Jing Song; Jong-I Mou; Calvin King

1998-05-18

190

Top quark mass and kinematics  

SciTech Connect

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.

Barberis, Emanuela; /Northeastern U.

2006-05-01

191

First order ball bearing kinematics  

NASA Technical Reports Server (NTRS)

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

Kingbury, E.

1984-01-01

192

Kinematic Parameters of Signed Verbs  

ERIC Educational Resources Information Center

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

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

2013-01-01

193

Sparse matrix inverse factors  

SciTech Connect

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

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

1990-05-01

194

Technical Note Pulmonary Kinematics From Tagged Hyperpolarized  

E-print Network

assessment of disease progression. Key Words: helium-3; registration; pulmonary kinematics; tagging J. MagnTechnical Note Pulmonary Kinematics From Tagged Hyperpolarized Helium-3 MRI Nicholas J. Tustison the feasibility of a novel method for quantifying 3D regional pulmonary kinematics from hyperpolarized helium-3

Utah, University of

195

HI in spiral galaxies Stellar kinematics  

E-print Network

Outline HI in spiral galaxies CO and H2 Stellar kinematics DYNAMICS OF GALAXIES 6. Observations 2008/9 Piet van der Kruit, Kapteyn Astronomical Institute Observations of kinematics #12;Outline HI in spiral galaxies CO and H2 Stellar kinematics Outline HI in spiral galaxies HI observations Analysis of HI

Kruit, Piet van der

196

Geophysical InversionFacility  

E-print Network

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

Oldenburg, Douglas W.

197

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

NASA Technical Reports Server (NTRS)

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

Nguyen, Charles C.; Pooran, Farhad J.

1989-01-01

198

Kinematic solution of spherical Stephenson-III six-bar mechanism  

NASA Astrophysics Data System (ADS)

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

Liu, Yanfang; Yang, Suixian

2013-09-01

199

Analysis of a closed-kinematic chain robot manipulator  

NASA Technical Reports Server (NTRS)

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

Nguyen, Charles C.; Pooran, Farhad J.

1988-01-01

200

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

NASA Astrophysics Data System (ADS)

The most common representation of sea ice dynamics in climate models assumes that sea ice is a quasi-continuous non-normal fluid with a viscous-plastic rheology. This rheology leads to non-linear sea ice momentum equations that are notoriously difficult to solve. Recently a Jacobian-free Newton-Krylov (JFNK) solver was shown to solve the equations accurately at moderate costs. This solver is extended for massive parallel architectures and vector computers and implemented in a coupled sea ice-ocean general circulation model for climate studies. Numerical performance is discussed along with numerical difficulties in realistic applications with up to 1920 CPUs. The parallel JFNK-solver's scalability competes with traditional solvers although the collective communication overhead starts to show a little earlier. When accuracy of the solution is required (i.e. reduction of the residual norm of the momentum equations of more that one or two orders of magnitude) the JFNK-solver is unrivalled in efficiency. The new implementation opens up the opportunity to explore physical mechanisms in the context of large scale sea ice models and climate models and to clearly differentiate these physical effects from numerical artifacts.

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

2014-01-01

201

Three-dimensional pose reconstruction of flexible instruments from endoscopic images  

Microsoft Academic Search

A position and orientation sensing system is de- veloped for the feedback control of endoscopic instruments in advanced flexible endoscopes. The images that are taken by the endoscopic camera are used to match a kinematic model to the observed instrument. Using the pseudo-inverse of the Jacobian of the forward kinematics, the estimated state of the model is continuously updated so

Rob Reilink; Stefano Stramigioli; Sarthak Misra

2011-01-01

202

Kinematic Fitting of Detached Vertices  

SciTech Connect

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

Paul Mattione

2007-05-01

203

Teaching Kinematics With Angry Birds  

NSDL National Science Digital Library

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

Rodrigues, Marcelo; Carvalho, Paulo

2013-09-24

204

Pythagoras Theorem and Relativistic Kinematics  

NASA Astrophysics Data System (ADS)

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

Mulaj, Zenun; Dhoqina, Polikron

2010-01-01

205

Uplifting amplitudes in special kinematics  

NASA Astrophysics Data System (ADS)

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

Goddard, Timothy; Heslop, Paul; Khoze, Valentin V.

2012-10-01

206

A "voice inversion effect?".  

PubMed

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 of a gender identification task on two syllables pronounced by 90 speakers (boys, girls, men, and women). Experiment 2 consisted of a speaker discrimination task on pairs of syllables (8 men and 8 women). Experiment 3 consisted of an instrument discrimination task on pairs of melodies (8 string and 8 wind instruments). In all three experiments, stimuli were presented in 4 conditions: (1) no inversion; (2) temporal inversion (e.g., backwards speech); (3) frequency inversion centered around 4000 Hz; and (4) around 2500 Hz. Results indicated a significant decrease in performance caused by sound inversion, with a much stronger effect for frequency than for temporal inversion. Interestingly, although frequency inversion markedly affected timbre for both voices and instruments, subjects' performance was still above chance. However, performance at instrument discrimination was much higher than for voices, preventing comparison of inversion effects for voices vs. non-vocal stimuli. Additional experiments will be necessary to conclude on the existence of a possible "voice inversion effect." PMID:15177788

Bédard, Catherine; Belin, Pascal

2004-07-01

207

Robust magnetotelluric inversion  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

208

Mississippi State Physics Labs: Kinematics  

NSDL National Science Digital Library

This resource is an introductory kinematics lab in which students use a motion sensor to analyze position, velocity, and acceleration vs. time graphs. Designed for use with Data Studio software, it provides step-by-step directions for setting up the interface with the sensor and tips on scaling the graphs. Students then graph data and compare to their own hypotheses. After analyzing simpler types of movement, the task is to think in "reverse" to match movements to more complex pre-drawn graphs. This item is part of a larger collection of labs for introductory physics by the authors.

Ferguson, Joe; Denson, Jack

2008-07-19

209

Kinematics in Vector Boson Fusion  

E-print Network

The vector boson fusion process leads to two forward/backward jets (tag jets) and the produced state, a Higgs boson in this case, moving slowly in the p-p C.M. frame at the LHC. For the case of Higgs decaying to W+W (W*) with Higgs mass below 180 GeV, the W bosons have low momentum in the Higgs C.M. For the case of W leptonic decays, this fact allows for an approximate reconstruction of the two final state neutrinos. In turn, those solutions then provide additional kinematic cuts against background.

D. Green

2006-03-02

210

Kinematic correction for roller skewing  

NASA Technical Reports Server (NTRS)

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

Savage, M.; Loewenthal, S. H.

1980-01-01

211

Physics Suite Thinking Problems: Kinematics  

NSDL National Science Digital Library

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

Redish, Edward F.

2008-07-18

212

Kinematically complete chemical reaction dynamics  

NASA Astrophysics Data System (ADS)

Kinematically complete studies of molecular reactions offer an unprecedented level of insight into the dynamics and the different mechanisms by which chemical reactions occur. We have developed a scheme to study ion-molecule reactions by velocity map imaging at very low collision energies. Results for the elementary nucleophilic substitution (SN2) reaction Cl- + CH3I ? ClCH3 + I- are presented and compared to high-level direct dynamics trajectory calculations. Furthermore, an improved design of the crossed-beam imaging spectrometer with full three-dimensional measurement capabilities is discussed and characterization measurements using photoionization of NH3 and photodissociation of CH3I are presented.

Trippel, S.; Stei, M.; Otto, R.; Hlavenka, P.; Mikosch, J.; Eichhorn, C.; Lourderaj, U.; Zhang, J. X.; Hase, W. L.; Weidemüller, M.; Wester, R.

2009-11-01

213

Basic concepts of kinematic-wave models  

USGS Publications Warehouse

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)

Miller, J.E.

1984-01-01

214

Algebra Lab: Inverse Variation  

NSDL National Science Digital Library

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

2012-01-01

215

Inverse Nyquist and INAP  

Microsoft Academic Search

This paper describes a programming language designed to perform inverse Nyquist analysis. The acronym INAP stands for Inverse Nyquist Analysis Programme. The INAP language is written in Fortran IVINAP is written for a design engineer in a control theory and\\/or electronic circuit application. The input is in conventional Laplace Transform form. The incoming data is actually accepted in equation form,

RICHARD A. NORTHOUSE

1973-01-01

216

Robust adaptive kinematic control of redundant robots  

NASA Technical Reports Server (NTRS)

The paper presents a general method for the resolution of redundancy that combines the Jacobian pseudoinverse and augmentation approaches. A direct adaptive control scheme is developed to generate joint angle trajectories for achieving desired end-effector motion as well as additional user defined tasks. The scheme ensures arbitrarily small errors between the desired and the actual motion of the manipulator. Explicit bounds on the errors are established that are directly related to the mismatch between actual and estimated pseudoinverse Jacobian matrix, motion velocity and the controller gain. It is shown that the scheme is tolerant of the mismatch and consequently only infrequent pseudoinverse computations are needed during a typical robot motion. As a result, the scheme is computationally fast, and can be implemented for real-time control of redundant robots. A method is incorporated to cope with the robot singularities allowing the manipulator to get very close or even pass through a singularity while maintaining a good tracking performance and acceptable joint velocities. Computer simulations and experimental results are provided in support of the theoretical developments.

Tarokh, M.; Zuck, D. D.

1992-01-01

217

Quantitative stratigraphic inversion  

NASA Astrophysics Data System (ADS)

We develop a methodology for systematic inversion of quantitative stratigraphic models. Quantitative stratigraphic modeling predicts stratigraphy using numerical simulations of geologic processes. Stratigraphic inversion methodically searches the parameter space in order to detect models which best represent the observed stratigraphy. Model parameters include sea-level change, tectonic subsidence, sediment input rate, and transport coefficients. We successfully performed a fully automated process based stratigraphic inversion of a geologically complex synthetic model. Several one and two parameter inversions were used to investigate the coupling of process parameters. Source location and transport coefficient below base level indicated significant coupling, while the rest of the parameters showed only minimal coupling. The influence of different observable data on the inversion was also tested. The inversion results using misfit based on sparse, but time dependent sample points proved to be better than the misfit based on the final stratigraphy only, even when sampled densely. We tested several inversion schemes on the topography dataset obtained from the eXperimental EarthScape facility simulation. The clustering of model parameters in most of the inversion experiments showed the likelihood of obtaining a reasonable number of compatible models. We also observed the need for several different dillusion-coefficient parameterizations to emulate different erosional and depositional processes. The excellent result of the piecewise inversion, which used different parameterizations for different time intervals, demonstrate the need for development or incorporation of time-variant parameterizations of the diffusion coefficients. We also present new methods for applying boundary condition on simulation of diffusion processes using the finite-difference method. It is based on the straightforward idea that solutions at the boundaries are smooth. The new scheme achieves high accuracy when the initial conditions are non vanishing at the boundaries, a case which is poorly handled by previous methods. Along with the ease in implementation, the new method does not require any additional computation or memory.

Sharma, Arvind Kumar

218

Hamstring Muscle Kinematics during Treadmill Sprinting  

E-print Network

,10,14). Despite the frequency of hamstring muscle injuries dur- ing sprinting, it remains unclear when in the gaitHamstring Muscle Kinematics during Treadmill Sprinting DARRYL G. THELEN1 , ELIZABETH S. CHUMANOV1. M. BEST, S. C. SWANSON, L. LI, M. YOUNG, and B. C. HEIDERSCHEIT. Hamstring Muscle Kinematics during

Wisconsin at Madison, University of

219

Kinematic Event Patterns in Speech: Special Problems.  

ERIC Educational Resources Information Center

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

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

2000-01-01

220

Philippine fault: A key for Philippine kinematics  

Microsoft Academic Search

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

E. Barrier; P. Huchon; M. Aurelio

1991-01-01

221

wm RisrR-408 Nonlinear Kinematic  

E-print Network

hardening function of this type, calibrated by any uniaxial stress-strain curve, is then proposed00 e t tf i tf (0 O o 0 o oo wm RisørR-408 Nonlinear Kinematic Hardening under Non NONLINEAR KINEMATIC HARDENING UNDER NON-PROPORTIONAL LOADING N.S. Ottosen Abstract. Nithin the framework

222

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

NASA Astrophysics Data System (ADS)

stochastic geostatistical inversion approach is widely used in subsurface inverse problems to estimate unknown parameter fields and corresponding uncertainty from noisy observations. However, the approach requires a large number of forward model runs to determine the Jacobian or sensitivity matrix, thus the computational and storage costs become prohibitive when the number of unknowns, m, and the number of observations, n increase. To overcome this challenge in large-scale geostatistical inversion, the Principal Component Geostatistical Approach (PCGA) has recently been developed as a "matrix-free" geostatistical inversion strategy that avoids the direct evaluation of the Jacobian matrix through the principal components (low-rank approximation) of the prior covariance and the drift matrix with a finite difference approximation. As a result, the proposed method requires about K runs of the forward problem in each iteration independently of m and n, where K is the number of principal components and can be much less than m and n for large-scale inverse problems. Furthermore, the PCGA is easily adaptable to different forward simulation models and various data types for which the adjoint-state method may not be implemented suitably. In this paper, we apply the PCGA to representative subsurface inverse problems to illustrate its efficiency and scalability. The low-rank approximation of the large-dimensional dense prior covariance matrix is computed through a randomized eigen decomposition. A hydraulic tomography problem in which the number of observations is typically large is investigated first to validate the accuracy of the PCGA compared with the conventional geostatistical approach. Then the method is applied to a large-scale hydraulic tomography with 3 million unknowns and it is shown that underlying subsurface structures are characterized successfully through an inversion that involves an affordable number of forward simulation runs. Lastly, we present a joint inversion of head and tracer test data using MODFLOW and MT3DMS as coupled black-box forward simulation solvers. These applications demonstrate the advantages of the PCGA, i.e., the scalability to high-dimensional inverse problems and the ability to utilize multiple forward models as black boxes.

Lee, J.; Kitanidis, P. K.

2014-07-01

223

Kinematics of Multigrid Monte Carlo  

E-print Network

We study the kinematics of multigrid Monte Carlo algorithms by means of acceptance rates for nonlocal Metropolis update proposals. An approximation formula for acceptance rates is derived. We present a comparison of different coarse-to-fine interpolation schemes in free field theory, where the formula is exact. The predictions of the approximation formula for several interacting models are well confirmed by Monte Carlo simulations. The following rule is found: For a critical model with fundamental Hamiltonian H(phi), absence of critical slowing down can only be expected if the expansion of in terms of the shift psi contains no relevant (mass) term. We also introduce a multigrid update procedure for nonabelian lattice gauge theory and study the acceptance rates for gauge group SU(2) in four dimensions.

M. Grabenstein; K. Pinn

1992-07-03

224

Kinematic model of southern California  

SciTech Connect

A kinematic model for southern California, based on late-Quaternary slip rates and orientations of major faults in the region, is proposed. Internally consistent motions are determined assuming that these faults bound rigid blocks. Relative to North America, most of California west of the San Andreas fault is moving parallel to the San Andreas fault through the Transverse Ranges and not parallel to the motion of the Pacific plate. The velocities of the blocks are calculated along several paths in southern California that begin in the Mojave Desert and end off the California coast. A path that crosses the western Transverse Ranges accumulates the accepted relative North America-Pacific plate velocity, whereas paths to the north and south result in a significant missing component of motion, implying the existence of a zone of active deformation in southern California. 70 references.

Weldon, R.; Humphreys, E.

1986-02-01

225

Kinematics of primate midfoot flexibility.  

PubMed

This study describes a unique assessment of primate intrinsic foot joint kinematics based upon bone pin rigid cluster tracking. It challenges the assumption that human evolution resulted in a reduction of midfoot flexibility, which has been identified in other primates as the "midtarsal break." Rigid cluster pins were inserted into the foot bones of human, chimpanzee, baboon, and macaque cadavers. The positions of these bone pins were monitored during a plantarflexion-dorsiflexion movement cycle. Analysis resolved flexion-extension movement patterns and the associated orientation of rotational axes for the talonavicular, calcaneocuboid, and lateral cubometatarsal joints. Results show that midfoot flexibility occurs primarily at the talonavicular and cubometatarsal joints. The rotational magnitudes are roughly similar between humans and chimps. There is also a similarity among evaluated primates in the observed rotations of the lateral cubometatarsal joint, but there was much greater rotation observed for the talonavicular joint, which may serve to differentiate monkeys from the hominines. It appears that the capability for a midtarsal break is present within the human foot. A consideration of the joint axes shows that the medial and lateral joints have opposing orientations, which has been associated with a rigid locking mechanism in the human foot. However, the potential for this same mechanism also appears in the chimpanzee foot. These findings demonstrate a functional similarity within the midfoot of the hominines. Therefore, the kinematic capabilities and restrictions for the skeletal linkages of the human foot may not be as unique as has been previously suggested. Am J Phys Anthropol 155:610-620, 2014. © 2014 Wiley Periodicals, Inc. PMID:25234343

Greiner, Thomas M; Ball, Kevin A

2014-12-01

226

Speeding up the learning of robot kinematics through function decomposition.  

PubMed

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

Ruiz de Angulo, Vicente; Torras, Carme

2005-11-01

227

Workspace and Kinematic Analysis of the VERNE machine  

E-print Network

This paper describes the workspace and the inverse and direct kinematic analysis of the VERNE machine, a serial/parallel 5-axis machine tool designed by Fatronik for IRCCyN. This machine is composed of a three-degree-of-freedom (DOF) parallel module and a two-DOF serial tilting table. The parallel module consists of a moving platform that is connected to a fixed base by three non-identical legs. This feature involves (i) a simultaneous combination of rotation and translation for the moving platform, which is balanced by the tilting table and (ii) workspace whose shape and volume vary as a function of the tool length. This paper summarizes results obtained in the context of the European projects NEXT ("Next Generation of Productions Systems").

Kanaan, Daniel; Chablat, Damien

2007-01-01

228

Effects of burial history, rock ductility and recovery magnitude on inversion of normal faulted strata  

E-print Network

, and are subjected to a two-stage deformation path of layer-parallel extension followed by coaxial contraction. To investigate the effects of burial depth and relative ductility on kinematics of inversion, five model suites were run in which confining pressure...

Kuhle, Nathan John

2012-06-07

229

Geological Inverse Theory Resources  

NSDL National Science Digital Library

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

Ganse, Andrew A.

2011-07-22

230

Borehole Resistivity Inversion  

E-print Network

In this paper we perform the inversion of borehole resistivity data using the software package developed by Western Atlas Logging Services, Houston, TX. Direct current resistivity methods, namely lateral sounding and ...

Garipova, Yulia V.

1997-01-01

231

Pant-tilt Platform Design Based on Parallel Kinematics  

NASA Astrophysics Data System (ADS)

A new long distance measurement system design, based on parallel kinematics, is presented in this paper. This system has two degrees of freedom for positioning and orientating two high precision cameras. In this document is presented the system design. Several configurations have been analyzed and the components needed such as actuators, linear captators (to measure the displacement), spherical ball-and-socket joints and universal joints, have been selected. The developed model allows us to obtain the kinematic joint variables, depending on geometric parameters, by means of the resolution of opened chains for each leg. The direct model allows us to obtain the platform position and orientation for a determined displacement values. Once the matrix transformation (which describes the coordinates of the platform reference system respect to the base reference system) is obtained, the actuators elongation can be found out through the inverse model with numeric or geometric methods. The design optimization, by means of the analysis of anchorage points and the study of singularities (analysis of the limited platform positions, depending on maximum strut lengths and maximum angle that joints can turn), allows us to optimize the workspace of the platform.

Majarena, A. C.; Santolaria, J.; Aguilar, J. J.; Pastor, J.; Cajal, Cajal

2009-11-01

232

Inverse Euler equations  

NASA Astrophysics Data System (ADS)

Following previous work by Keller [2], that is extended to compressible flow, the general time-independent Euler equations for inviscid fluid flow are first written in a perfectly antisymmetric form, using a pair of stream functions as the dependent variables. In a second step the equations are written in an inverse form, using the two stream functions and the natural coordinate as independent variables. As a special case the Bragg-Hawthorne equation for axisymmetric flow is first extended to compressible flow and also transformed to its inverse form. The main advantage of using these inverse equations is associated with the possibilities of using static pressure distributions, Mach number distributions, geometric constraints, etc., or any combination of geometric constraints and specifications of physical quantities to define the boundary conditions. In contrast to conventional inverse methods, that are based on iterative approximations to a desired pressure distribution along the surface of a flow device, for example, the use of inverse Euler equations offers the possibility to arrive at the solution for any kind of boundary conditions in a single step. Furthermore, there is no need for complicated grid generation procedures, because the domain of definition in inverse space is typically a cube with Cartesian coordinates. In the original space, the surfaces on which the natural coordinate is constant are orthogonal to the streamlines. As a consequence, the computation time can be kept small and the accuracy is remarkably high. This semi-orthogonal curvilinear grid is generated automatically together with the solution. The density of grid lines is automatically getting large in domains where gradients are large. Possible difficulties with using inverse Euler equations are mainly related to the topology of the flow field. The transform to inverse coordinates must correspond to a one-to-one mapping. Hence, if the domain of definition is not simply connected it must be cut suitably to obtain piecewise domains for which one-to-one mappings exist.

Keller, J. J.

233

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

NASA Astrophysics Data System (ADS)

The Discontinuous Galerkin (DG) method for compressible fluid flows is incorporated into the Jacobian-Free Newton-Krylov (JFNK) framework. Advantages of combining the DG with the JFNK are two-fold: a) enabling robust and efficient high-order-accurate modeling of all-speed flows on unstructured grids, opening the possibility for high-fidelity simulation of nuclear-power-industry-relevant flows; and b) ability to tightly, robustly and high-order-accurately couple with other relevant physics (neutronics, thermal-structural response of solids, etc.). In the present study, we focus on the physics-based preconditioning (PBP) of the Krylov method (GMRES), used as the linear solver in our implicit higher-order-accurate Runge-Kutta (ESDIRK) time discretization scheme; exploiting the compactness of the spatial discretization of the DG family. In particular, we utilize the Implicit Continuous-fluid Eulerian (ICE) method and investigate its efficacy as the PBP within the JFNK-DG method. Using the eigenvalue analysis, it is found that the ICE collapses the complex components of the all eigenvalues of the Jacobian matrix (associated with pressure waves) onto the real axis, and thereby enabling at least an order of magnitude faster simulations in nearly-incompressible/weakly-compressible regimes with a significant storage saving.

Park, Hyeongkae; Nourgaliev, Robert; Knoll, Dana

2007-11-01

234

The inverse electroencephalography pipeline  

NASA Astrophysics Data System (ADS)

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

Weinstein, David Michael

235

Stellar kinematics in the galactic centre  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

236

Inverting Source Time Functions to determine the fault kinematic characteristics  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

237

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

Microsoft Academic Search

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

Mongkol Thianwiboon; Viboon Sangveraphunsiri

2005-01-01

238

Some Results on Inverse Scattering  

E-print Network

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

A. G. Ramm

2007-10-19

239

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

Microsoft Academic Search

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

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

2008-01-01

240

Shape Approximation in Kinematic Systems Ernest Davis #  

E-print Network

, Philip Davis, Drew McDermott, Bud Mishra, Igor Najfeld, Chee Yap, and Ken Yip. 1 #12; calculations basedShape Approximation in Kinematic Systems Ernest Davis # New York University 251 Mercer St. New York

Davis, Ernest

241

DEPLOYABLE ANTENNA KINEMATICS USING TENSEGRITY STRUCTURE DESIGN  

E-print Network

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

Florida, University of

242

Kinematical coincidence method in transfer reactions  

NASA Astrophysics Data System (ADS)

A new method to extract high resolution angular distributions from kinematical coincidence measurements in binary reactions is presented. Kinematics is used to extract the center of mass angular distribution from the measured energy spectrum of light particles. Results obtained in the case of 10Be+p?9Be+d reaction measured with the CHIMERA detector are shown. An angular resolution of few degrees in the center of mass is obtained. The range of applicability of the method is discussed.

Acosta, L.; Amorini, F.; Auditore, L.; Berceanu, I.; Cardella, G.; Chatterjiee, M. B.; De Filippo, E.; Francalanza, L.; Gianì, R.; Grassi, L.; Grzeszczuk, A.; La Guidara, E.; Lanzalone, G.; Lombardo, I.; Loria, D.; Minniti, T.; Pagano, E. V.; Papa, M.; Pirrone, S.; Politi, G.; Pop, A.; Porto, F.; Rizzo, F.; Rosato, E.; Russotto, P.; Santoro, S.; Trifirò, A.; Trimarchi, M.; Verde, G.; Vigilante, M.

2013-07-01

243

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

NASA Astrophysics Data System (ADS)

Imaging a high resolution spatio-temporal slip distribution of an earthquake rupture is a core research goal in seismology. In general we expect to obtain a higher quality source image by improving the observational input data (e.g. using more, higher quality, near field stations). However, recent studies show that increasing the surface station density alone does not significantly improve source inversion results (Custodio et al. 2005; Zhang et al. in review). Song et al. (2009) and Song and Dalguer (2013) found interesting correlation structures between kinematic source parameters (e.g. slip, peak slip velocity and rupture velocity) obtained both from kinematic inversion and dynamic modeling. These correlation structures that effectively regularize the model space may improve source imaging more than by simply improving the observational data. In this 'pseudo-dynamic' source inversion, source images are constrained by both physical constraints derived from rupture dynamics as well all the observational data, without compromising the computational efficiency of kinematic inversion. We investigate the efficiency of the pseudo-dynamic source inversion using synthetic dynamic rupture models. Our target model is a buried vertical strike-slip event (Mw 7.3) in a homogeneous half space. In the inversion, we model low frequency (below 1Hz) waveforms using a genetic algorithm in a Bayesian framework (Moneli et al. 2008). A dynamically consistent regularized Yoffe function (Tinti, et al. 2005) was applied as a single-window slip velocity function. We have first implemented the autocorrelation of slip in the prior distribution in the Bayesian inversion - preliminary results show that estimated kinematic source models closely match the target dynamic model. The prior information describing the auto-correlation of source parameters (e.g. slip) improves the imaging of spatial distribution of source parameters. By implementing both auto- and cross-correlation of kinematic source parameters, we can regularize the model space in a more physics-based manner and improve the source imaging more significantly compared to using traditional smoothing constraints. Further investigation is needed to tune the related parameters of pseudo-dynamic source inversion and relative weighting between the prior and the likelihood function in the Bayesian inversion.

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

2014-05-01

244

Structure of the Galaxy Kinematics of the Galaxy  

E-print Network

Outline Structure of the Galaxy Kinematics of the Galaxy Galactic dynamics STRUCTURE OF GALAXIES 1. Structure, kinematics and dynamics of the Galaxy Piet van der Kruit Kapteyn Astronomical Institute Structure, kinematics and dynamics of the Galaxy #12;Outline Structure of the Galaxy Kinematics

Kruit, Piet van der

245

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

NASA Technical Reports Server (NTRS)

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

Bayo, Eduardo; Ledesma, Ragnar

1993-01-01

246

An Inverse Spectral Theorem  

E-print Network

We prove a substantial extension of an inverse spectral theorem of Ambarzumyan, and show that it can be applied to arbitrary compact Riemannian manifolds, compact quantum graphs and finite combinatorial graphs, subject to the imposition of Neumann (or Kirchhoff) boundary conditions.

E. B. Davies

2010-10-01

247

Inverses and Elementary Matrices  

NSDL National Science Digital Library

Created by David Smith for the Connected Curriculum Project, the purpose of this module is to explore the properties of inverse matrices. Our principal tool for this exploration is the expression of elementary row operations as left multiplications by elementary matrices. This is part of a larger collection of learning modules hosted by Duke University.

Smith, David

2010-05-18

248

Lecture Notes Inverse Problems  

E-print Network

speaking, inverse problems are concerned with finding causes for an observed effect or a desired effect for the cause for an observed effect. · Control or design, if one looks for a possible cause of a desired effect (identifiability), because there is probably a specific cause f

Münster, Westfälische Wilhelms-Universität

249

Structured Adaptive Model Inversion  

E-print Network

in adaptive controllers for entry vehicles. #12;7 Mars Entry - Trajectory 500km - Circular Orbit ~125 kmStructured Adaptive Model Inversion Controller for Mars Atmospheric Flight Carolina Restrepo #12;2 Research Team - 2007 #12;3 Overview Research Motivation Objectives and Scope Mars Entry Vehicle

Valasek, John

250

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

SciTech Connect

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

Bernsen, Erik, E-mail: e.bernsen@uu.n [Institute for Marine and Atmospheric research Utrecht, Utrecht University (Netherlands); Dijkstra, Henk A. [Institute for Marine and Atmospheric research Utrecht, Utrecht University (Netherlands); Thies, Jonas; Wubs, Fred W. [Johann Bernoulli Institute for Mathematics and Computer Science, Groningen University (Netherlands)

2010-10-20

251

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

252

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

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

253

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

NASA Astrophysics Data System (ADS)

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.

Rambely, A. S.; Fazrolrozi

254

Kinematic Analysis of a Serial - Parallel Machine Tool: the VERNE machine  

E-print Network

The paper derives the inverse and the forward kinematic equations of a serial - parallel 5-axis machine tool: the VERNE machine. This machine is composed of a three-degree-of-freedom (DOF) parallel module and a two-DOF serial tilting table. The parallel module consists of a moving platform that is connected to a fixed base by three non-identical legs. These legs are connected in a way that the combined effects of the three legs lead to an over-constrained mechanism with complex motion. This motion is defined as a simultaneous combination of rotation and translation. In this paper we propose symbolical methods that able to calculate all kinematic solutions and identify the acceptable one by adding analytical constraint on the disposition of legs of the parallel module.

Kanaan, Daniel; Chablat, Damien; 10.1016/j.mechmachtheory.2008.03.002

2008-01-01

255

Interplanetary stream magnetism - Kinematic effects  

NASA Technical Reports Server (NTRS)

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

Burlaga, L. F.; Barouch, E.

1976-01-01

256

Parallel Inversion of Sparse Matrices  

Microsoft Academic Search

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

Ramon Betancourt; Fernando L. Alvarado

1986-01-01

257

Silk inverse opals  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

258

Kinematic reconstruction of the Caribbean region since the Early Jurassic  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

259

Direct and Inverse Variation  

NSDL National Science Digital Library

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

Media, Annenberg

2009-12-23

260

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

NASA Astrophysics Data System (ADS)

Finite-fault source inversions estimate kinematic rupture parameters of earthquakes using a variety of available data sets and inversion approaches. Rupture models are obtained by solving an inherently ill-posed inverse problem, subject to numerous a priori assumptions and noisy observations. Despite these limitations, near real-time source inversions are becoming increasingly popular, while we still face the dilemma that uncertainties in such finite-fault source inversions are poorly understood. Yet, the accurate estimation of earthquake rupture properties, including proper uncertainty quantification, is critically important for earthquake seismology and seismic hazard analysis, as they help to adequately characterize earthquake complexity across all scales. The Source Inversion Validation (SIV) project (http://equake-rc.info/sivdb) is a multi-institutional collaboration that attempts to quantify the intra-event variability in rupture models (see the SRCMOD database, http://equake-rc.info/srcmod), and that aims to develop robust uncertainty metrics for earthquake source inversions. The SIV collaboration features an open online platform to examine the current state-of-the-art in earthquake source inversion, but also to test novel source inversion approaches, based on a sequence of benchmark exercises with variable degree of complexity. In this presentation, we summarize initial SIV results related to previous benchmark exercises, discuss the latest findings for a test case of a complex rupture embedded in a 3D heterogeneous Earth model, and propose metrics to quantify rupture-model variability, quality of data fitting, and model robustness.

Mai, P. M.; Gallovic, F.

2013-12-01

261

A unified approach for local resolution of kinematic redundancy with inequality constraints and its application to nuclear power plant  

Microsoft Academic Search

In this paper, a closed-form formulation for inverse kinematics for redundant manipulators with inequality constraints has been proposed. This formulation has been derived by using the Kuhn-Tucker condition, the Lagrange multiplier method, and the active\\/working set method, so that its solution may satisfy the necessary and sufficient condition for optimization subject to equality and inequality constraints. From the formulation, computationally

K. C. Park; P. H. Chang; J. Kenneth Salisbury

1997-01-01

262

Inverse Problems in Systems Biology  

E-print Network

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

Fulmek, Markus

263

Inverse Problems. Activities for Undergraduates  

Microsoft Academic Search

This book is a valuable introduction to inverse problems. In particular, from the educational point of view, the author addresses the questions of what constitutes an inverse problem and how and why we should study them. Such an approach has been eagerly awaited for a long time. Professor Groetsch, of the University of Cincinnati, is a world-renowned specialist in inverse

Masahiro Yamamoto

2003-01-01

264

Control of flexible, kinematically redundant robot manipulators  

NASA Astrophysics Data System (ADS)

The use of kinematic redundancy in control algorithms to avoid singularities evade obstacles minimize joint torques manipulator kinetic energy end effector contact forces etc. . . has been among the most active research topics in the field of robotics in the past few years. However these approaches have been associated mainly with rigid manipulators where there is no unpredictable flexible motions. When dealing with flexible manipulators the flexibility of the system will cause undesired inaccuracy in end effector motion. If these manipulators are kinematically redundant their kinematic redundancy can be used to compensate for the end effector motion inaccuracy and in many cases help damp out the vibrations. This paper examines this issue and introduces new control algorithms designed to regulate the flexibility while maintaining precise tracking of the end effector trajectory. The dynamic model used is a special case of the general multi-body dynamics designed to maximize its computational efficiency.

Nguyen, Luong A.; Walker, Ian D.; de Figueiredo, Rui J. P.

1991-02-01

265

INVERSE PROBLEMS IN HEAT TRANSFER Nicholas Zabaras  

E-print Network

stochastic inverse heat-conduction problem (SIHCP): Problem definition stochastic methods in inverse modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 17.3A BAYESIAN APPROACH TO THE INVERSE HEAT-CONDUCTION PROBLEM

Zabaras, Nicholas J.

266

Graph Theory Roots of Spatial Operators for Kinematics and Dynamics  

NASA Technical Reports Server (NTRS)

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

Jain, Abhinandan

2011-01-01

267

Auditory coding of human movement kinematics.  

PubMed

Although visual perception is dominant on motor perception, control and learning, auditory information can enhance and modulate perceptual as well as motor processes in a multifaceted manner. During last decades new methods of auditory augmentation had been developed with movement sonification as one of the most recent approaches expanding auditory movement information also to usually mute phases of movement. Despite general evidence on the effectiveness of movement sonification in different fields of applied research there is nearly no empirical proof on how sonification of gross motor human movement should be configured to achieve information rich sound sequences. Such lack of empirical proof is given for (a) the selection of suitable movement features as well as for (b) effective kinetic-acoustical mapping patterns and for (c) the number of regarded dimensions of sonification. In this study we explore the informational content of artificial acoustical kinematics in terms of a kinematic movement sonification using an intermodal discrimination paradigm. In a repeated measure design we analysed discrimination rates of six everyday upper limb actions to evaluate the effectiveness of seven different kinds of kinematic-acoustical mappings as well as short-term learning effects. The kinematics of the upper limb actions were calculated based on inertial motion sensor data and transformed into seven different sonifications. Sound sequences were randomly presented to participants and discrimination rates as well as confidence of choice were analysed. Data indicate an instantaneous comprehensibility of the artificial movement acoustics as well as short-term learning effects. No differences between different dimensional encodings became evident thus indicating a high efficiency for intermodal pattern discrimination for the acoustically coded velocity distribution of the actions. Taken together movement information related to continuous kinematic parameters can be transformed into the auditory domain. Additionally, pattern based action discrimination is obviously not restricted to the visual modality. Artificial acoustical kinematics might be used to supplement and/or substitute visual motion perception in sports and motor rehabilitation. PMID:24800411

Vinken, Pia M; Kröger, Daniela; Fehse, Ursula; Schmitz, Gerd; Brock, Heike; Effenberg, Alfred O

2013-01-01

268

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

269

Kinematics of the symbiotic system R Aqr  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

270

Consistency of Listing's law and reciprocal innervation with pseudo-inverse control of eye position in 3-D  

Microsoft Academic Search

Pseudo-inverse kinematics, under which small movements are produced by the least possible sum square changes in motor command, has been proposed as a unifying principle for the elimination of redundancy in general biological motor control systems (Pellionisz 1984) and in particular in the oculomotor system (Daunicht 1988, 1991). We have noted elsewhere (Dean et al. 1999) that this principle is

Paul A. Warren; John Porrill; Paul Dean

2004-01-01

271

Calibration of parallel kinematic devices using sequential determination of kinematic parameters  

SciTech Connect

In PKM Machines, the Cartesian position and orientation of the tool point carried on the platform is obtained from a kinematic model of the particular machine. Accurate positioning of these machines relies on the accurate knowledge of the parameters of the kinematic model unique to the particular machine. The parameters in the kinematic model include the spatial locations of the joint centers on the machine base and moving platform, the initial strut lengths, and the strut displacements. The strut displacements are readily obtained from sensors on the machine. However, the remaining kinematic parameters (joint center locations, and initial strut lengths) are difficult to determine when these machines are in their fully assembled state. The size and complexity of these machines generally makes it difficult and somewhat undesirable to determine the remaining kinematic parameters by direct inspection such as in a coordinate measuring machine. In order for PKMs to be useful for precision positioning applications, techniques must be developed to quickly calibrate the machine by determining the kinematic parameters without disassembly of the machine. A number of authors have reported techniques for calibration of PKMs (Soons, Masory, Zhuang et. al., Ropponen). In two other papers, the authors have reported on work recently completed by the University of Florida and Sandia National Laboratories on calibration of PKMs, which describes a new technique to sequentially determine the kinematic parameters of an assembled parallel kinematic device. The technique described is intended to be used with a spatial coordinate measuring device such as a portable articulated CMM measuring arm (Romer, Faro, etc.), a Laser Ball Bar (LBB), or a laser tracker (SMX< API, etc.). The material to be presented is as follows: (1) methods to identify the kinematic parameters of 6--6 variant Stewart platform manipulators including joint center locations relative to the workable and spindle nose, and initial strut lengths, (2) and example of the application of the method, and (3) results from the application of the technique.

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

2000-04-06

272

End effector constrained path planning for 7DOF manipulator  

Microsoft Academic Search

This paper presents more reliable and fast path planning method for end effector constrained 7DOF redundant manipulators. Conventional path planning for redundant manipulators used jacobian based planning method for convenience. But it is not easy to apply in case of constrained tasks and redundant manipulators. On the contrary in this paper we uses position based path planning by inverse kinematics.

Kyongmo Koo; Xin Jiang; Atsushi Konno; Masaru Uchiyama

2010-01-01

273

An Inversion Model  

NSDL National Science Digital Library

This demonstration allows students to visualize inversion in a fluid, explain it in terms of density, and apply the concept to weather systems and convection. Materials required include four Ehrlenmeyer flasks, two thin glass plates, a heat source, and food coloring. The investigation supports material presented in chapter 7, What Causes Thunderstorms and Tornadoes?, in the textbook Energy flow, part of Global System Science, an interdisciplinary course for high school students that emphasizes how scientists from a wide variety of fields work together to understand significant problems of global impact.

274

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

E-print Network

Tee, Rui Yan, Yuanwei Chua, Haizhou Li and Zhiyong Huang Abstract-- In this paper, we present a method and smoothness preserved. Simulation study on a 7 degree-of-freedom (DOF) robot arm shows a tradeoff of tracking

Huang, Zhiyong

275

Submitted to: IEEE International Conference on Robotics and Automation (ICRA 2000) Inverse Kinematics for Humanoid Robots  

E-print Network

-2 Hikaridai, Seika-cho, Soraku-gun, 619-02 Kyoto, Japan Abstract: Real-time control of the endeffector as external kine- matic trajectories--as opposed to complete task-level con- trol laws-- on systems with many

Schaal, Stefan

276

A biomimetic approach to inverse kinematics for a redundant robot arm  

E-print Network

Redundant robots have received increased attention during the last decades, since they provide solutions to problems investigated for years in the robotic community, e.g. task-space tracking, obstacle avoidance etc. However, ...

Artemiadis, Panagiotis

277

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

278

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

E-print Network

in industry like welding robot, painting robot, pick-and- place robot, and also in space robotics. Most of the robots are designed with a specific application in mind and detailed knowledge of working environment is required. Fur- thermore the control... in industry like welding robot, painting robot, pick-and- place robot, and also in space robotics. Most of the robots are designed with a specific application in mind and detailed knowledge of working environment is required. Fur- thermore the control...

Gupta, Gautam Jagannath

2012-06-07

279

Kinematic conditioning augmentation to haptic interface for teleoperation  

E-print Network

A solution is proposed for the kinematic conditioning problem in teleoperation. The proposed solution helps the operator in understanding the kinematic conditioning of the slave manipulator with the help of haptic interface. Teleoperation involves...

Dongaonkar, Ranjeet Manohar

2012-06-07

280

Kinematics of foldable discrete space cranes  

NASA Technical Reports Server (NTRS)

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.

Nayfeh, A. H.

1985-01-01

281

Compound nucleus studies withy reverse kinematics  

SciTech Connect

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

Moretto, L.G.

1985-06-01

282

Large kinematic error propagation in revolute manipulators  

Microsoft Academic Search

Understanding how errors propagate in serial revolute manipulators is important for developing better designs and planning algorithms, as well as understanding the practical limitations on accuracy of multi- link arms. In this paper we provide a systematic propagation method- ology and numerical example that illustrates how large kinematic errors propagate by convolution on the Euclidean motion group.

Yunfeng Wang; Gregory S. Chirikjian

283

Kinematic analysis of reaching in the cat  

Microsoft Academic Search

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

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

1995-01-01

284

Kinematics of media with continuously changing topology  

Microsoft Academic Search

The fundamental postulate of continuum mechanics states that a body is a three-dimensional differentiable manifold and its motions are diffeomorphisms. Simple thought experiments with cyclic motions of dislocations show that they do not preserve topology (set of neighborhoods). The same is valid for chaotic and turbulent motions with coarse-graining. To describe such motions, kinematics of a generalized continuum mechanics is

I. A. Kunin

1990-01-01

285

A Kinematic Analysis of Grenade Throwing  

Microsoft Academic Search

Background: In military action, the grenade is a useful weapon for use at a distance against the enemy. When training soldiers to throw grenade, various injuries occur during practice. Therefore, it is necessary to understand the mechanism of the throwing process, in order to avoid injuries effectively. Methods: This study used 2 high-speed cameras (120 Hz) to collect kinematic throwing

Hung-Maan Lee; Wu-Chou Chen

2004-01-01

286

Kinematics of young stars. I. Local irregularities  

NASA Astrophysics Data System (ADS)

The local velocity field of young stars is dominated by the galactic rotation, the kinematics of the Gould Belt and the nearest OB associations and open clusters, and the kinematics of the spiral structure. We re-examined here this local velocity field by using a large sample of nearby O and B stars from the Hipparcos Catalogue. The high quality astrometric data are complemented with a careful compilation of radial velocities and Strömgren photometry, which allows individual photometric distances and ages to be derived. The Gould Belt extends up to 600 pc from the Sun with an inclination with respect to the galactic plane of iG = 16-22degr and the ascending node placed at Omega G = 275-295degr . Approximately 60% of the stars younger than 60 Myr belong to this structure. The values found for the Oort constants when different samples selected by age or distance were used allowed us to interpret the systematic trends observed as signatures induced by the kinematic behaviour of the Gould Belt. The contribution of Sco-Cen and Ori OB1 complexes in the characterization of the expansion of the Gould Belt system is also discussed. We found that a positive K-term remains when these aggregates are excluded. From the kinematic behaviour of the stars and their spatial distribution we derive an age for the Gould Belt system in the interval 30-60 Myr. Based on data from the Hipparcos astrometry satellite (European Space Agency)}

Torra, J.; Fernández, D.; Figueras, F.

2000-07-01

287

KINEMATIC DISTANCE ASSIGNMENTS WITH H I ABSORPTION  

SciTech Connect

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

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

2012-07-01

288

Deployable antenna kinematics using tensegrity structure design  

Microsoft Academic Search

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

Byron Franklin Knight

2000-01-01

289

Multiplicative AF kinematic hardening in plasticity  

Microsoft Academic Search

The basic innovation proposed in this work is to consider one of the two coefficients of the Armstrong and Frederick (AF) evolution equation for the back stress, function of another dimensionless second order internal variable evolving also according to an AF equation in what can be called a multiplicative AF kinematic hardening rule. Introducing the foregoing modification into some of

Yannis F. Dafalias; Kyriakos I. Kourousis; George J. Saridis

2008-01-01

290

Wellposedness of Kinematic Hardening Models in Elastoplasticity  

Microsoft Academic Search

We consider a certain type of rate independent elastoplastic constitutive laws for nonlinear kinematic hardening which include the models of Frederick-Armstrong, Bower and Mroz. We prove results concerning existence, uniqueness and continuous dependence for the stress-strain evolution considered as a function of time (but not of space). As an auxiliary result, we also prove a theorem concerning the Lipschitz continuity

Martin Brokate

291

Kinematic-Wave Furrow Irrigation Model  

Microsoft Academic Search

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

Wynn R. Walker; Allan S. Humpherys

1983-01-01

292

Bill Goodwine 1 Controllability of Kinematic  

E-print Network

Bill Goodwine 1 Controllability of Kinematic Control Systems on Stratified Configuration Spaces Bill Goodwine and Joel Burdick June 27, 1996 Slide 0 #12;Bill Goodwine 2 Motivating Examples · Many are controllable. #12;Bill Goodwine 3 in Contact Left Foot in Contact Right Foot Both Feet in Contact Neither Foot

Goodwine, Bill

293

Computer Software & Programing Utilization in Kinematics.  

ERIC Educational Resources Information Center

This paper discusses two software packages used in kinematics courses at Purdue University, Calumet (Indiana) and some algorithms written by students for cam design. The first software package, 4BAR, requires the user to define the particular four bar linkage in terms of lengths of the individual links and the angle and distance to the coupler…

Zahraee, Mohammad A.; And Others

294

Kinematic Measurements from YouTube Videos  

ERIC Educational Resources Information Center

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

Ruiz, Michael J.

2009-01-01

295

KINEMATICAL ANALYSIS OF FEMALE VOLLEYBALL SPIKE  

Microsoft Academic Search

The purpose of this study was to analyze female volleyball players' body centre of mass (CM) displacement and velocity when spiking at front and back row. Six high school players participated in this study. Two JVC9800 digital video cameras (120Hz) were used to collect spiking motion. Kwon 3D motion system was used to analyze the kinematic variables. The results indicated

Ying-Cheng Chen; Chen-Fu Huang

296

A Nate on Dynamics and Kinematics*  

E-print Network

and the former is used to signify physical constraints responsible for particular forms of motion. If technical includes studies in naive physics as well as studies on the kinematic specification of dynamics and. more & Resnick. 1981; Mach. 1893/1960; Maxwell. 1877/1920; Merriam-Webster. 1949; Sommerfield. 1942; Stein. 1981

297

Kinematic Dynamos and the Earth's Magnetic Field  

Microsoft Academic Search

The Bullard-Gellman formalism is applied to investigate the existence of convergent solutions for steady kinematic dynamos. It is found that the solutions for the Bullard-Gellman dynamo, as well as for Lilley's modification of it, do not converge. Convergent solutions have been found for a class of spherical convective cells which would be stationary in a perfect fluid in the absence

C. L. Pekeris; Y. Accad; B. Shkoller

1973-01-01

298

THE ORTHOGLIDE: KINEMATICS AND WORKSPACE ANALYSIS  

E-print Network

, they are generally operated at low speed to avoid excessive vibration and deflection. Conversely, parallel kinematic joints, links and actuators. Thus, while having good operating characteristics (large workspace and high of similar 1-d.o.f. joints; (ii) regular workspace shape properties with bounded velocity amplification

Boyer, Edmond

299

Study on kinematics modeling of mobile robot in rough terrain  

Microsoft Academic Search

Kinematics modeling is an indispensable component for dead reckoning of mobile robot. Aimed at this problem in rough terrain, the kinematics model is analyzed by the rigid-body kinematical constraints of mobile robot that is on the basis of locomotion architecture with the wheeled and rocker-bogie suspension system. At the same time, a method of kinematics model integrated with wheel-ground contact

Yu Jinxia; Cai Zixing; Duan Zhuohua

2009-01-01

300

Three-dimensional kinematics of hummingbird flight.  

PubMed

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

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

2007-07-01

301

Kinematic hardening rules for modeling uniaxial and multiaxial ratcheting  

Microsoft Academic Search

Ratcheting, which is the strain accumulation observed under the unsymmetrical stress controlled loading and non-proportional loadings, is modeled using the simplified viscoplasticity theory based on overstress (VBO). The influences of kinematic hardening laws on the uniaxial and multiaxial non-proportional ratcheting behavior of CS 1026 carbon steel have been investigated. The following kinematic hardening rules have been considered: the classical kinematic

Ozgen U. Colak

2008-01-01

302

Learning Kinematics with a V-Scope: A Case Study  

NSDL National Science Digital Library

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

Trumper, Ricardo

2006-10-11

303

Parallel Kinematic Machine Tools – Current State and Future Potentials  

Microsoft Academic Search

Parallel kinematics have recently attracted attention as machine tools because of their conceptual potentials in high motion dynamics and accuracy combined with high structural rigidity due to their closed kinematic loops. This paper, prepared with input from CIRP colleagues as well as of machine manufacturers and end-users involved in PKM, attempts to review the development of parallel kinematics for machine

M. Weck; D. Staimer

2002-01-01

304

Kinematics and Dynamic Stability of the Locomotion of Polio Patients  

E-print Network

Kinematics and Dynamic Stability of the Locomotion of Polio Patients Yildirim Hurmuzlu , Cagatay kinematics and dynamics of polio survivors. Phase plane portraits and first return maps were used as graphical tools to detect abnormal patterns in the sagittal kinematics of polio gait. Two new scalar

Basdogan, Cagatay

305

Methodological analysis of finite helical axis behavior in cervical kinematics.  

PubMed

Although a far more stable approach compared to the six degrees of freedom analysis, the finite helical axis (FHA) struggles with interpretational difficulties among health professionals. The analysis of the 3D-motion axis has been used in clinical studies, but mostly limited to qualitative analysis. The aim of this study is to introduce a novel approach for the quantification of the FHA behavior and to investigate the effect of noise and angle intervals on the estimation of FHA parameters. A simulation of body movement has been performed introducing Gaussian noise on position and orientation of a virtual sensor showing linear relation between the simulated noise and the error in the corresponding parameter. FHA axis behavior was determined by calculating the intersection points of the FHA with a number of planes perpendicular to the FHA using the Convex Hull (CH) technique. The angle between the FHA and each of the IHA was also computed and its distribution was also analyzed. Input noise has an inversely proportional relationship with the angle steps of FHA estimation. The proposed FHA quantification approach can be useful to provide new approaches to researchers and to improve insight for the clinician in order to better understand joint kinematics. PMID:24916306

Cescon, Corrado; Cattrysse, Erik; Barbero, Marco

2014-10-01

306

Squatting Exercises in Older Adults: Kinematic and Kinetic Comparisons  

PubMed Central

Purpose Squatting activities may be used, within exercise programs, to preserve physical function in older adults. This study characterized the lower-extremity peak joint angles, peak moments, powers, work, impulse, and muscle recruitment patterns (electromyographic; EMG) associated with two types of squatting activities in elders. Methods Twenty-two healthy, older adults (ages 70–85) performed three trials each of: 1) a squat to a self-selected depth (normal squat; SQ) and 2) a squat onto a chair with a standardized height of 43.8 cm (chair squat; CSQ). Descending and ascending phase joint kinematics and kinetics were obtained using a motion analysis system and inverse dynamics techniques. Results were averaged across the three trials. A 2 × 2 (activity × phase) ANOVA with repeated measures was used to examine the biomechanical differences among the two activities and phases. EMG temporal characteristics were qualitatively examined. Results CSQ generated greater hip flexion angles, peak moments, power, and work, whereas SQ generated greater knee and ankle flexion angles, peak moments, power, and work. SQ generated a greater knee extensor impulse, a greater plantar flexor impulse and a greater total support impulse. The EMG temporal patterns were consistent with the kinetic data. Conclusions The results suggest that, with older adults, CSQ places greater demand on the hip extensors, whereas SQ places greater demand on the knee extensors and ankle plantar flexors. Clinicians may use these discriminate findings to more effectively target specific lower-extremity muscle groups when prescribing exercise for older adults. PMID:12673148

FLANAGAN, SEAN; SALEM, GEORGE J.; WANG, MAN-YING; SANKER, SERENA E.; GREENDALE, GAIL A.

2012-01-01

307

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

SciTech Connect

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

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

2011-01-01

308

A study of generalized inverses  

E-print Network

A STUDY OF GENERALIZED INVERSES A Thesis by NANCY LEE MCKINNEY Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE August 1973 Major Subject: Mathematics A... STUDY OF GENERALIZED INVERSES A Thesis by NANCY LEE MCKINNEY Approved as to style and content by: airman o ittee Hea o epartment e er Me er August 1973 ABSTRACT A Study of Generalized Inverses. (August 1973) Nancy Lee NcKinney, B. A...

McKinney, Nancy Lee

2012-06-07

309

Inverse problem in hydrogeology  

NASA Astrophysics Data System (ADS)

The state of the groundwater inverse problem is synthesized. Emphasis is placed on aquifer characterization, where modelers have to deal with conceptual model uncertainty (notably spatial and temporal variability), scale dependence, many types of unknown parameters (transmissivity, recharge, boundary conditions, etc.), nonlinearity, and often low sensitivity of state variables (typically heads and concentrations) to aquifer properties. Because of these difficulties, calibration cannot be separated from the modeling process, as it is sometimes done in other fields. Instead, it should be viewed as one step in the process of understanding aquifer behavior. In fact, it is shown that actual parameter estimation methods do not differ from each other in the essence, though they may differ in the computational details. It is argued that there is ample room for improvement in groundwater inversion: development of user-friendly codes, accommodation of variability through geostatistics, incorporation of geological information and different types of data (temperature, occurrence and concentration of isotopes, age, etc.), proper accounting of uncertainty, etc. Despite this, even with existing codes, automatic calibration facilitates enormously the task of modeling. Therefore, it is contended that its use should become standard practice. L'état du problème inverse des eaux souterraines est synthétisé. L'accent est placé sur la caractérisation de l'aquifère, où les modélisateurs doivent jouer avec l'incertitude des modèles conceptuels (notamment la variabilité spatiale et temporelle), les facteurs d'échelle, plusieurs inconnues sur différents paramètres (transmissivité, recharge, conditions aux limites, etc.), la non linéarité, et souvent la sensibilité de plusieurs variables d'état (charges hydrauliques, concentrations) des propriétés de l'aquifère. A cause de ces difficultés, le calibrage ne peut êtreséparé du processus de modélisation, comme c'est le cas dans d'autres cas de figure. Par ailleurs, il peut être vu comme une des étapes dans le processus de détermination du comportement de l'aquifère. Il est montré que les méthodes d'évaluation des paramètres actuels ne diffèrent pas si ce n'est dans les détails des calculs informatiques. Il est montré qu'il existe une large panoplie de techniques d'inversion : codes de calcul utilisables par tout-un-chacun, accommodation de la variabilité via la géostatistique, incorporation d'informations géologiques et de différents types de données (température, occurrence, concentration en isotopes, âge, etc.), détermination de l'incertitude. Vu ces développements, la calibration automatique facilite énormément la modélisation. Par ailleurs, il est souhaitable que son utilisation devienne une pratique standardisée. Se sintetiza el estado del problema inverso en aguas subterráneas. El énfasis se ubica en la caracterización de acuíferos, donde los modeladores tienen que enfrentar la incertidumbre del modelo conceptual (principalmente variabilidad temporal y espacial), dependencia de escala, muchos tipos de parámetros desconocidos (transmisividad, recarga, condiciones limitantes, etc), no linealidad, y frecuentemente baja sensibilidad de variables de estado (típicamente presiones y concentraciones) a las propiedades del acuífero. Debido a estas dificultades, no puede separarse la calibración de los procesos de modelado, como frecuentemente se hace en otros campos. En su lugar, debe de visualizarse como un paso en el proceso de enten dimiento del comportamiento del acuífero. En realidad, se muestra que los métodos reales de estimación de parámetros no difieren uno del otro en lo esencial, aunque sí pueden diferir en los detalles computacionales. Se discute que existe amplio espacio para la mejora del problema inverso en aguas subterráneas: desarrollo de códigos amigables alusuario, acomodamiento de variabilidad a través de geoestadística, incorporación de información geológica y diferentes tipos de datos (temperatura, presencia y co

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

2005-03-01

310

Stress inversion assumptions review  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

311

Inverse magnetorheological fluids.  

PubMed

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

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

2014-09-01

312

A classification of finite quantum kinematics  

NASA Astrophysics Data System (ADS)

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

Tolar, J.

2014-10-01

313

Kinematics of swimming garter snakes (Thamnophis sirtalis).  

PubMed

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

Munk, Yonatan

2008-06-01

314

'Spontaneous' ways of reasoning in elementary kinematics  

NSDL National Science Digital Library

The aim of this study was to explore and analyse 'spontaneous' ways of reasoning (SWR) of students in elementary kinematics (uniform motion in Galilean frames). A set of experiments presented to 80 eleven-year-old children and to some 700 first- and fourth-year university students showed types of right and wrong answer which varied little from one sample of pupils to another. It seems difficult to attribute these results solely to school learning; but they can be well accounted for if the authors assume the existence of an organised system which the authors call the 'natural model', as opposed to the kinematic model of the physicists. This model involves two components which always interact: a purely descriptive one describing motion, and a causal one explaining motion.

Saltiel, E.; Malgrange, J. L.

2005-11-23

315

Kinematics of tt¯ events at CDF  

NASA Astrophysics Data System (ADS)

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

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

1999-05-01

316

A conceptual approach to teaching kinematics  

NSDL National Science Digital Library

Results from research on student understanding of velocity and acceleration have been used to guide the development of a conceptual approach to teaching kinematics. The authors describe how instruction based on the observation of actual motions can help students: (1) develop a qualitative understanding of velocity as a continuously varying quantity, of instantaneous velocity as a limit, and of uniform acceleration as the ratio of the change in instantaneous velocity to the elapsed time; (2) distinguish the concepts of position, velocity change of velocity, and acceleration from one another; and (3) make connections among the various kinematical concepts, their graphical representations, and the motions of real objects. Instructional strategies designed to address specific difficulties identified in the investigation are illustrated by example.

Rosenquist, Mark; Mcdermott, Lillian C.

2005-10-20

317

Kinematic structures in galactic disc simulations  

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

318

First-order ball-bearing kinematics  

NASA Technical Reports Server (NTRS)

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

Kingsbury, E.

1985-01-01

319

Kinematics and dynamics of sphenisciform wings  

NASA Astrophysics Data System (ADS)

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.

Noca, Flavio; Crisinel, Fabien; Munier, Pierre

2011-11-01

320

Effective kinematic viscosity of turbulent He II  

Microsoft Academic Search

The temperature dependence of the effective kinematic viscosity of turbulent He II, {sub eff}(T), is deduced from second sound attenuation data using the late stage of decay of thermally induced counterflow He II turbulence in two channels of square cross section. It is shown to qualitatively agree with the published data for {sub eff}(T) calculated based on experiments on decaying-grid-generated

T. V. Chagovets; A. V. Gordeev; L. Skrbek

2007-01-01

321

Identification of top quarks using kinematic variables  

Microsoft Academic Search

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

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

1995-01-01

322

Bubble kinematics in a sheared foam  

E-print Network

We characterize the kinematics of bubbles in a sheared two-dimensional foam using statistical measures. We consider the distributions of both bubble velocities and displacements. The results are discussed in the context of the expected behavior for a thermal system and simulations of the bubble model. There is general agreement between the experiments and the simulation, but notable differences in the velocity distributions point to interesting elements of the sheared foam not captured by prevalent models.

Yuhong Wang; Kapilanjan Krishan; Michael Dennin

2006-07-05

323

The Galactic Kinematics of Mira Variables  

E-print Network

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

Michael Feast

2002-07-09

324

Morhology and kinematics of eta Carinae  

E-print Network

We present a high-resolution image of $\\eta$~Car. Together with IR and visual observations of the central arcsecond, we use this to discuss the morphological structure of $\\eta$~Car on the different length scales. We identify three different structural components: a bipolar outflow, an equatorial disk of streamers, and the speckle objects. We discuss models for the kinematics of the whole complex, and propose observations that could settle the question of the structure of $\\eta$~Car.

W. J. Duschl; K. -H. Hofmann; F. Rigaut; G. Weigelt

1994-10-28

325

Application Limits for the Kinematic Wave Approximation  

Microsoft Academic Search

Flows with predominate flow direction are governed by the de Saint Venant flow equations. The kinematic wave approach retains the mass balance but considers pseudo-uniform flow conditions instead of the full momentum ba- lance. This approximation is particularly well-suited for overland runoff pro- cesses. The zero-inertia approach may be regarded as an intermediate formula- tion which retains the effect of

Willi H. Hager; Kurt Hager

1985-01-01

326

Kinematic analysis of prehension movements in children  

Microsoft Academic Search

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

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

1998-01-01

327

Kinematics of Distant Galaxies from Keck  

E-print Network

DEEP is a two-phase spectral survey of faint field galaxies with the Keck Telescopes. The goals include exploring galaxy formation and evolution, mapping distant large scale structures, and constraining cosmology. DEEP, since its inception in the early 1990's, has been distinguished by an emphasis on studying the kinematics and masses of distant galaxies. The major DEEP survey in the second phase (DEEP2) is scheduled to begin in 2002 using a new spectrograph and will mainly aim for a sample of 50,000 galaxies to I ~ 23. Until then, the first phase of DEEP science programs will have been concentrating on using existing Keck spectrographs to undertake spectral surveys of over 1000 galaxies that have also been observed with HST. I will highlight the study of rotation curves of distant spirals; the fundamental plane of faint, high-redshift E/S0s; the narrow velocity widths seen in luminous blue compact galaxies; and the diversity of kinematics seen in a small sample of high redshift (z ~ 3) galaxies. These DEEP pilot programs have clearly demonstrated the feasibility, importance, and potential of using kinematics to better understand distant galaxies.

David C. Koo

2001-12-27

328

New Kinematical Constraints on Cosmic Acceleration  

SciTech Connect

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

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

2007-05-25

329

The Large Magellanic Cloud: Structure and Kinematics  

E-print Network

I review our understanding of the structure and kinematics of the Large Magellanic Cloud (LMC), with a particular focus on recent results. This is an important topic, given the status of the LMC as a benchmark for studies of microlensing, tidal interactions, stellar populations, and the extragalactic distance scale. I address the observed morphology and kinematics of the LMC; the angles under which we view the LMC disk; its in-plane and vertical structure; the LMC self-lensing contribution to the total microlensing optical depth; the LMC orbit around the Milky Way; and the origin and interpretation of the Magellanic Stream. Our understanding of these topics is evolving rapidly, in particular due to the many large photometric and kinematic datasets that have become available in the last few years. It has now been established that: the LMC is considerably elongated in its disk plane; the LMC disk is thicker than previously believed; the LMC disk may have warps and twists; the LMC may have a pressure-supported halo; the inner regions of the LMC show unexpected complexities in their vertical structure; and precession and nutation of the LMC disk plane contribute measurably to the observed line-of-sight velocity field. However, many open questions remain and more work is needed before we can expect to converge on a fully coherent structural, dynamical and evolutionary picture that explains all observed features of the LMC.

Roeland P. van der Marel

2004-04-08

330

Modular theory of inverse systems  

NASA Technical Reports Server (NTRS)

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

1979-01-01

331

Model View of Inversion Evolution.  

National Technical Information Service (NTIS)

The evolution of low clouds and fog trapped under winter valley inversions can be a challenging forecast problem. Typically, model guidance struggles simply to forecast the inversion itself and has very little to add in terms of forecasting where low clou...

T. Barker

2008-01-01

332

8, 64696499, 2008 Inverse modeling  

E-print Network

cal- culated with the decoupled direct method in three dimensions (DDM-3D) implemented5 within Screen / Esc Printer-friendly Version Interactive Discussion Abstract An inverse modeling methodACPD 8, 6469­6499, 2008 Inverse modeling method for spatially-resolved NOx emissions S. L

Boyer, Edmond

333

Kinematics and evolution of eruptive prominences of two different basic types  

NASA Astrophysics Data System (ADS)

The kinematics and the evolution of three eruptive prominences (EPs) observed in Wroclaw, Poland were studied. Two of them are classical examples for the two basic different types of eruption (type I and type II, according to Rompolt, 1984). Their basic kinematic characteristics were compared and discussed from the point of view of their associations with topologically different parts of the erupting huge magnetic system. Some essential differences in their kinematics and evolution were established. The kinematics and evolution of type I arch EP of 5 May 1980 and the type II EP of 8 May 1979, associated with coronal mass ejections (CMEs), are radically different. The arch EP of 5 May 1980, associated with fast CME, rose with increasing acceleration up to its complete disappearing, while the eruption of the EP of 8 May 1979, associated with slow CME, was consisted of two phases: acceleration and constant velocity. The eruption of EP of type II was followed by a final, post-eruptive phase when the prominence plasma fell back to the chromosphere. The EPs of types I and II showed two kind of horizontal expansions (HE): large-scale, apparent horizontal expansion and small-scale displacements between threads feet composing the EP legs. These two kinds of HE are strongly distinguished for the EP of type I. The large-scale expansion of the arch legs lasts up to the end of the eruption and the alternative small-scale displacement change of the threads feet in the arch legs is still present. The two kinds of HE take place in two consecutive stages during the evolution of the EP of type II. The first stage is characterized by an alternative small-scale displacement change of the threads feet in the EP leg occurred during the eruptive phase up to the full untwisting of the EP body threads. Second stage is presented by a large-scale HE of the fully untwisted threads occurred during the EP post-eruptive phase. The EP of 14 August 1979 associated with fast CME shows kinematics and evolution of the eruption, as well as a horizontal expansion very similar to these ones of the type II EPs. Some differences in kinematic patterns of the EP of 14 August 1979 and those one of 8 May 1979 are probably due to its different topologies of the magnetic field configuration (normal and inverse), as well as its association with a different type of CMEs (fast and slow).

Duchlev, P.; Koleva, K.; Kokotanekova, J.; Dechev, M.; Petrov, N.; Rompolt, B.; Rudawy, P.

334

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

NASA Astrophysics Data System (ADS)

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

Kotlarski, Jens; Heimann, Bodo; Ortmaier, Tobias

2012-06-01

335

Intensity-based source inversion of the destructive earthquake of 1694 in the southern Apennines, Italy  

NASA Astrophysics Data System (ADS)

inverted the regional pattern of intensities of the catastrophic earthquake of 1694 in the southern Apennines and determined the geometrical and kinematic characteristics of its source, including the double-couple orientation (strike angle 299° ± 10°, dip 54° ± 12°, and rake 309° ± 11°; pure dip-slip solution not precluded). The objective nonlinear inversion was performed using the simple 11 parameter kinematic-function model (KF) with a niching genetic algorithm technique. The similarity between the pattern of the field intensities of the 1694 earthquake and the synthetic pattern is striking. This result is supported by the fact that our inversion technique was verified in the study area, where it was able to again find the source of the Ms 6.9 Irpinia 1980 earthquake, known from instruments and from field surveys of the rupture. This type of inversion enables researchers to exploit the extensive intensity data from Italy and other countries to extend the knowledge of seismotectonic activity to preinstrumental times. New paleoseismological evidence and even published descriptions of the fault rupture by witnesses of the 1694 earthquake were found, confirming our results. We also present and apply a new algorithm, of general interest, to calculate disorientations between double-couples via standard linear algebra. The 3-D rotations that bring the pairwise orthogonal unit vectors that were estimated by our intensity inversion into the instrumental triples of the 1980 Irpinia earthquake, assumed as benchmarks, provide verification of our algorithm.

Sirovich, Livio; Pettenati, Franco; Cavallini, Fabio

2013-12-01

336

Temperature inversion in China seas  

NASA Astrophysics Data System (ADS)

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.

Hao, Jiajia; Chen, Yongli; Wang, Fan

2010-12-01

337

Bayesian inversion with applications to physics Bayesian inversion  

E-print Network

, to the dedicatees, I send my deepest love and thanks for their support. I hope this thesis goes some way of inverse problem. A crucial step in formulating the solution is the identification of a suitable prior

Guo, Zaoyang

338

Kinematics of transition during human accelerated sprinting  

PubMed Central

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

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

2014-01-01

339

A Kinematical Approach to Dark Energy Studies  

SciTech Connect

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

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

2006-06-06

340

Kinematics of transition during human accelerated sprinting.  

PubMed

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

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

2014-01-01

341

Experiments for the determination of kinematic parameters from optical flow, based on a robust displacement estimated method  

NASA Astrophysics Data System (ADS)

A method for the determination of the optical flow from a series of single pictures, which is especially valuable for the evaluation of natural scenes, is presented. The relation between the kinematic parameters of the camera motion and the resulting optical flow was established. The inversion of these equations allows the determination of the motion parameters. A calibrated series of pictures, for which the motion of the camera was a priori known, was evaluated. The experiment shows that the motion can be determined to a good approximation. Television pictures of a three-dimensional, strongly structured scene were evaluated. For comparison, the optical flow vectors were also determined with a correlation method. The deduced kinematic parameters for both methods agree well.

Kories, R.; Zimmermann, G.; Zinner, H.

342

Automobile Collisions, Kinematics and Related Injury Patterns  

PubMed Central

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

Siegel, A. W.

1972-01-01

343

Galaxy kinematics from counter-dispersed imaging  

E-print Network

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

N. G. Douglas; K. Taylor

1998-09-04

344

Kinematical and mechanical aspects of wafer slicing  

NASA Astrophysics Data System (ADS)

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

Werner, P. G.

1982-02-01

345

Quantum simulation of noncausal kinematic transformations.  

PubMed

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

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

2013-08-30

346

Physics Suite Peer Instruction Problems: Kinematics  

NSDL National Science Digital Library

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

Redish, Edward F.

2008-08-11

347

Kinematic Rupture Process Of Karakocan-Elazig Earthquake, Eastern Turkey  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

348

Kinematic analysis of tongue movement control in spastic dysarthria  

E-print Network

This study provided a quantitative analysis of the kinematic deviances in dysarthria associated with spastic cerebral palsy. Of particular interest were tongue tip movements during alveolar consonant release. Our analysis based on EMA measures indicated that speakers with spastic dysarthria had a restricted range of articulation and disturbances in articulatory-voicing coordination. The degree of kinematic deviances was greater for lower intelligibility speakers, supporting an association between articulatory dysfunctions and intelligibility in spastic dysarthria. Index Terms: dysarthria, kinematic analysis, EMA 1.

Heejin Kim; Panying Rong; Torrey M. Loucks; Mark Hasegawa-johnson

2010-01-01

349

Kinematic Design to Improve Ergonomics in Human Machine Interaction  

Microsoft Academic Search

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

André Schiele; Frans C. T. van der Helm

2006-01-01

350

The 2011, Mw 6.2, Christchurch earthquakes (New Zealand): faults geometry and source kinematics  

NASA Astrophysics Data System (ADS)

The geometrical characteristics and the space-time distribution of the kinematic source parameters of the 21 February 2011, Mw 6.2, Christchurch earthquake, New Zealand, have been inferred through a joint inversion of geodetic and strong-motion data. The geodetic data consist of both Global Position System (GPS), from campaign and continuous stations, and Synthetic Aperture Radar (SAR) interferograms from two ascending satellite tracks. The strong-motion data have been recorded at 10 stations located in the Canterbury Plane, offering a quite good azimuthal coverage of the event. Before performing the data inversion, several preliminary analyses on individual data-sets have been carried out, in order to find the optimal lay-out for the inversion. In particular, the consistency between GPS and InSAR data was checked and some GPS measurements, characterized by large errors, were excluded from the data-set. The strong-motion analyses were instead primarily addressed, to identify the reliable frequency range to be used, through the analysis of stability of S-wave polarization. The kinematic rupture model was obtained using the nonlinear joint inversion scheme proposed by Delouis et al. (2000), which is based on the simulated annealing algorithm. In particular, for any sub-source in which the fault plane is discretized, we explore for the direction, duration and amplitude of the slip vector, and for the rupture offset time. The geometry and orientation of the fault plane to be used in the inversion procedure is preliminarily inferred from the analysis of the geodetic data. In order to account for the complex pattern of the superficial deformation data (especially of the InSAR data), we adopted a source model consisting of two partially overlapping fault segments, whose dimensions are 15x11 and 7x7 km2, and striking at 60o and 10o, respectively. From the data inversion we found a slip distribution for the largest plane characterized by a high slip area, with a maximum amplitude of 4.2 m, localized at NE of the hypocenter. The second fault plane activated with a delay of about 4s, and a maximum slip of 2 m. Moreover, the total Source Time Function considering the two events has a total duration of about 7 s. The global seismic moment resulting from the joint inversion is about 3.0x1025 dyne cm (Mw 6.2), with an average rupture velocity of 2.0 km/s, and most of the energy release occurring on the main fault plane. The source parameters resolution is studied using both the single and joint data-sets, and applying the errors analysis for the retrieved kinematic rupture model.

Toraldo Serra, E.; Delouis, B.; Emolo, A.; Zollo, A.

2012-12-01

351

Geophysical Inversion Tutorials and Workflows  

NSDL National Science Digital Library

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

2011-07-01

352

Temperature Inversions Have Cold Bottoms.  

ERIC Educational Resources Information Center

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

Bohren, Craig F.; Brown, Gail M.

1982-01-01

353

Action understanding as inverse planning  

E-print Network

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

Baker, Christopher Lawrence

354

Trans-dimensional finite-fault inversion  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

355

Inverse Dynamics in Cycling Performance  

Microsoft Academic Search

Joint reaction forces and moments are of great interest for cyclists, coaches, therapists and medics because they give information\\u000a about muscular effort and therefore cycling technique. The objective of this study is to examine the influence of pedalling\\u000a rate and power on joint moments. An own mechanical construction was used to measure pedal forces, kinematic data was recorded\\u000a and joint

Malte Wangerin; Syn Schmitt; Björn Stapelfeldt; Albert Gollhofer

356

Friction Stir Welding at MSFC: Kinematics  

NASA Technical Reports Server (NTRS)

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

Nunes, A. C., Jr.

2001-01-01

357

Nuclear Rings in Galaxies - A Kinematic Perspective  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

358

Kinematics of signature writing in healthy aging.  

PubMed

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

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

2014-07-01

359

The kinematics of turbulent boundary layer structure  

NASA Technical Reports Server (NTRS)

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

Robinson, Stephen Kern

1991-01-01

360

Kinematics of the SWEEPS transiting planet candidates  

NASA Astrophysics Data System (ADS)

In 2004 a deep sequence of HST images of the Bulge was used to identify sixteen transiting extrasolar planet candidates (the SWEEPS candidates; Sahu et al. 2006), of which at least seven are likely to be true planets. Of these, SWEEPS-4 is almost certainly in the disk, and was shown through radial velocity followup to contain a planetary companion; the identification of the remaining fifteen candidates was left undetermined. We have used a repeat visit in 2006 to attach proper motions to some 180,000 objects, including all sixteen SWEEPS candidates. This has allowed us to build a sample of bulge stars to unprecedented purity. A population of more than 13,000 bulge objects is kinematically isolated, with fewer than thirty disk contaminants. We use the mean bulge and disk populations to test the balance of kinematic associations for the sixteen SWEEPS candidates. Assuming both the detectability and the astrophysical false-positive fraction to be similar for disk and bulge, we find the fraction of stars with planets in the bulge to be consistent with that in the disk.

Clarkson, Will; Sahu, Kailash; Anderson, Jay; Smith, T. Ed; Brown, Thomas M.; Casertano, Stefano; Rich, R. Michael; Bond, Howard E.; Livio, Mario; Minniti, Dante; Panagia, Nino; Renzini, Alvio; Valenti, Jeff; Zoccali, Manuela

2009-02-01

361

Inverse Compton Scattering in Mildly Relativistic Plasma  

NASA Technical Reports Server (NTRS)

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

Molnar, S. M.; Birkinshaw, M.

1998-01-01

362

Supersymmetry, the ILC, and the LHC inverse problem  

NASA Astrophysics Data System (ADS)

We report the results of the first large scale examination of the MSSM parameter space at the International Linear Collider (ILC). In particular, we address the question of whether or not the ILC can help to resolve the LHC Inverse Problem within this context. We examine 242 randomly generated but representative points in the MSSM parameter space which were found to lead to somewhat difficult signatures at the LHC. Including full Standard Model backgrounds and a fast detector simulation, our study finds that only roughly one third of these scenarios lead to visible signatures of some kind with a significance ?5 at the ILC with ?{s}=500 GeV. However, kinematically accessible charged sparticles are visible over 90% of the time. Furthermore, we examine these points in the parameter space pairwise and find that only one third of the pairs produce distinguishable signatures at the ILC at 5 ?. Going to a 1 TeV center of mass energy would substantially improve this situation since the dominant limitations are kinematic in origin.

Berger, C. F.; Gainer, J. S.; Hewett, J. L.; Lillie, B.; Rizzo, T. G.

2009-06-01

363

Canopy Components Temperature Retrieval through Bayesian inversion of Directional measurements  

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

364

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

SciTech Connect

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.

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

2010-09-01

365

Path Jacobians: Theory and Applications  

Microsoft Academic Search

In accordance with Fermat's Variation Principle, a ray path connecting two arbitrary points in a scene via multiple reflectors is given by a non-linear system. If we fix one of the two points and let the other change, the system can be considered as a function relating the reflection points along the path to the varying point. In this paper,

Min Chen; James Arvo

1998-01-01

366

Deployable antenna kinematics using tensegrity structure design  

NASA Astrophysics Data System (ADS)

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

Knight, Byron Franklin

367

Kinematics of prestack shot-geophone migration Christiaan C. Stolk  

E-print Network

Kinematics of prestack shot-geophone migration Christiaan C. Stolk , University of Twente, Maarten migration methods based on data binning pro- duce kinematic artifacts, i.e. coherent events-geophone ("survey sinking") migration, on the other hand, does not produce such artifacts when events to be migrated

Stolk, Chris

368

Kinematics of shot-geophone migration Christiaan C. Stolk1  

E-print Network

Kinematics of shot-geophone migration Christiaan C. Stolk1 , Maarten V. de Hoop2 , and William W. Symes3 ABSTRACT Recent analysis and synthetic examples have shown that many prestack depth migration with a kinematically correct migration velocity field, if this velocity field is highly refractive.This pathology

Stolk, Chris

369

Stellar and Ionized Gas Kinematics of Peculiar Virgo Cluster Galaxies  

NASA Astrophysics Data System (ADS)

We present the results of the stellar and ionized gas kinematics of 13 bright peculiar Virgo cluster galaxies. The stellar velocity field are mostly consistent with a rotation pattern, but some of them shows interesting features such as; Sshaped stellar isovelocity contours in NGC 4064, and signatures of kinematical distinct components in NGC 4429, and NGC 4698.

Cortés, J. R.; Kenney, J. D. P.; Hardy, E.

370

Modeling of Wheeled Mobile Robots using Dextrous Manipulation Kinematics  

E-print Network

Modeling of Wheeled Mobile Robots using Dextrous Manipulation Kinematics Joseph Auchter, Carl Moore Camber (PVC). We show that PVC elimi- nates kinematic slip for an outdoor robot. Both for- ward (auchtjo@eng.fsu.edu) and Carl Moore (camoore@eng.fsu.edu) are with the Center for Intelligent Systems

Collins, Emmanuel

371

Methods for kinematic modeling of biological and robotic systems  

Microsoft Academic Search

The main objective is to develop methods that automatically generate kinematic models for the movements of biological and robotic systems. Two methods for the identification of the kinematics are presented. The first method requires the elimination of the displacement variables that cannot be measured while the second method attempts to estimate the changes in these variables. The methods were tested

Mohamed Ouerfelli; Vijay Kumar; William S. Harwin

2000-01-01

372

Hand-hold location and trunk kinematics during box handling.  

PubMed

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

Haddad, Omid; Mirka, Gary A

2010-08-01

373

An Audiovisual Test of Kinematic Primitives for Visual Speech Perception  

Microsoft Academic Search

Isolated kinematic properties of visible speech can provide information for lip reading. Kinematic facial information is isolated by darkening an actor’s face and attaching dots to various articulators so that only moving dots can be seen with no facial features present. To test the salience of these images, the authors conducted experiments to determine whether the images could visually influence

Lawrence D. Rosenblum; Helena M. Saldaña

1996-01-01

374

KINEMATIC CONTROL OF THE MAGELLAN-ISR MOBILE ROBOT  

Microsoft Academic Search

A kinematic controller in Cartesian coordinates is proposed in this paper for application in mobile robot with differential driving. Lyapunov-like analysis is employed in the control system stability proof. Real time implementations and simulations results are also presented and discussed for the trajectory tracking and point stabilization cases. The performance of the controller is evaluated and compared with kinematic controller

Elder Moreira Hemerly

375

Scapular kinematics during humeral elevation in adults and children  

Microsoft Academic Search

Background. Appropriate motion of the scapula is important for dynamic positioning of the glenoid during humeral elevation. A number of studies have described the typical scapular kinematics during humeral elevation in adults. However, children and adults may have differences in scapulothoracic musculature and scapular osteology. To our knowledge, no study has been performed examining scapular kinematics in children with either

Sudarshan Dayanidhi; Margo Orlin; Scott Kozin; Susan Duff; Andrew Karduna

2005-01-01

376

Lingual Kinematics during Rapid Syllable Repetition in Parkinson's Disease  

ERIC Educational Resources Information Center

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

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

2012-01-01

377

Kinematic Clues to the Formation and Evolution of Galaxies  

E-print Network

Kinematic Clues to the Formation and Evolution of Galaxies A thesis presented by Sheila Jane awakened in me iii #12; iv #12; Kinematic Clues to the Formation and Evolution of Galaxies Advisor: Daniel of galaxies with counterrotating gas and stars provides fossil evidence for past interactions and mergers

Kannappan, Sheila

378

Modified kinematic hardening rules for simulations of ratchetting  

Microsoft Academic Search

In order to simulate multiaxial ratchetting, and as a preliminary step, common different variables introduced into the dynamic recovery term of recently developed hardening rules are presented and scrutinized in details. Subsequently, two modified kinematic hardening rules are formulated and presented. The proposed modified rules are based on the Ohno–Wang kinematic hardening rule in which accumulated plastic strain increment is

Mohammad Abdel-Karim

2009-01-01

379

MECHANICS OF FORWARD FLIGHT IN BUMBLEBEES I. KINEMATICS AND MORPHOLOGY  

Microsoft Academic Search

Summary Using high-speed cinematography, bumblebees in free flight were filmed over a range of forward airspeeds. A detailed description of the wing tip and body kinematics was obtained from a three-dimensional reconstruction of the two- dimensional film image. A technique for determining quantitatively the angle of attack of the wing was developed. Kinematic parameters found to vary consist- ently with

R. DUDLEY; C. P. ELLINGTON

380

Direct measurements of the kinematics and dynamics of bat flight  

Microsoft Academic Search

Experimental measurements and analysis of the flight of bats are presented, including kinematic analysis of high-speed stereo videography of straight and turning flight, and measurements of the wake velocity field behind the bat. The kinematic data reveal that, at relatively slow flight speeds, wing motion is quite complex, including a sharp retraction of the wing during the upstroke and a

Xiaodong Tian; Jose Iriarte-Diaz; Kevin Middleton; Ricardo Galvao; Emily Israeli; Abigail Roemer; Allyce Sullivan; Arnold Song; Sharon Swartz; Kenneth Breuer

2006-01-01

381

The impact of tibial torsion measurements on gait analysis kinematics  

PubMed Central

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

Lucareli, Paulo Roberto Garcia; Santos, Nadia Maria; Godoy, Wagner De; Bernal, Milena Moreira Barreto; Paes, Ângela Tavares; Ramalho, Amancio

2014-01-01

382

A method for determination of upper extremity kinematics  

Microsoft Academic Search

Kinematic analysis of the upper extremity has been conducted using a wide variety of techniques, philosophies, and analytic methods. We describe a simple, marker-based three-dimensional video analytic technique that borrows concepts from lower extremity kinematic analysis. A sequential rotation order about orthogonal axes is described, although alternate methods are examined as well. The method has been verified by application to

George Rab; Kyria Petuskey; Anita Bagley

2002-01-01

383

A School Experiment in Kinematics: Shooting from a Ballistic Cart  

ERIC Educational Resources Information Center

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

Kranjc, T.; Razpet, N.

2011-01-01

384

Reconstructing the knee joint mechanism from kinematic data Irene Reichla  

E-print Network

Reconstructing the knee joint mechanism from kinematic data Irene Reichla *, Winfried Auzingerb by several groups approximates the healthy human knee joint as a compound hinge joint with minimal varus. For this purpose, knee joint motion is simulated to generate kinematic data without noise and with normally

Weinmüller, Ewa B.

385

Practical Kinematics for Real-time Implementation of Continuum Robots  

Microsoft Academic Search

This paper introduces new analyses and algo- rithms which are essential for the practical implementation of continuous backbone continuum robots. Actuator length limits strongly shape the configuration or joint space of continuum manipulators, introducing couplings which are not reflected in previously published kinematic models. These unmodeled effects significantly restrict the practical application of previously estab- lished kinematic models on continuum

Bryan A. Jones; William Mcmahan; Ian D. Walker

2006-01-01

386

Sensitivity analysis of kinematic approximations in dynamic medusan swimming models  

Microsoft Academic Search

Models of medusan swimming typically rely on kinematic approximations to observed animal morphology to make such investigations tractable. The effect of these simplifications on the accuracy of predicted dynamics has not been examined in detail. We conduct a case study of the scyphozoan jellyfish Chrysaora fuscescens to isolate and quantify the sensitivity of dynamic models to common kinematic approximations. It

John O. Dabiri; Morteza Gharib

2003-01-01

387

IMAGES. I. Strong evolution of galaxy kinematics since z = 1  

Microsoft Academic Search

Nearly half the stellar mass of present-day spiral galaxies has formed since z = 1, and galaxy kinematics is an ideal tool to identify the underlying mechanisms responsible for the galaxy mass assembly since that epoch. Here, we present the first results of the ESO large program, ``IMAGES'', which aims at obtaining robust measurements of the kinematics of distant galaxies

Y. Yang; H. Flores; F. Hammer; B. Neichel; M. Puech; N. Nesvadba; A. Rawat; C. Cesarsky; M. Lehnert; L. Pozzetti; I. Fuentes-Carrera; P. Amram; C. Balkowski; H. Dannerbauer; S. di Serego Alighieri; B. Guiderdoni; A. Kembhavi; Y. C. Liang; G. Östlin; C. D. Ravikumar; D. Vergani; J. Vernet; H. Wozniak

2008-01-01

388

Inverse problems in scattering and acoustics  

Microsoft Academic Search

This dissertation work will describe two topics: the inverse problem of scattering and the inverse problem of acoustics. For the inverse problem of scattering, we consider the uniqueness in the inverse obstacle scattering with general conductive boundary conditions. The idea is based on the original work of Isakov for transmission boundary conditions, which utilizes the solvability of the direct problem,

Nicolas Pedro Valdivia

2002-01-01

389

High fidelity numerical simulation of airfoil thickness and kinematics effects on flapping airfoil propulsion  

E-print Network

High fidelity numerical simulation of airfoil thickness and kinematics effects on flapping airfoil online 17 July 2013 Keywords: Flapping airfoil Airfoil thickness Kinematics High order Navier-digit airfoils. Airfoil thickness and kinematics effects on the flapping airfoil propulsion

Hu, Hui

390

A kinematic model of southern California.  

USGS Publications Warehouse

We propose a kinematic model for southern California based on late Quaternary slip rates and orientations of major faults in the region. Internally consistent motions are determined assuming that these faults bound rigid blocks. The velocities of the blocks are calculated along several paths that begin in the Mojave Desert and end off the California coast. A path that crosses the western Transverse Ranges accumulates the accepted relative North America-Pacific plate velocity, whereas paths to the north and south result in a significant missing component of motion. This implies the existence of a zone of active deformation in southern California that is interpreted to include the western Transverse Ranges and northwest trending, predominately strike-slip faults close to the coast both north and south of the Transverse Ranges. Strain on this system accounts for about a third of the total North America- Pacific plate motion. -from Authors

Weldon, R.; Humphreys, E.

1986-01-01

391

Relativistic kinematics for motion faster than light  

NASA Technical Reports Server (NTRS)

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

Jones, R. T.

1982-01-01

392

Effective kinematic viscosity of turbulent He II.  

PubMed

The temperature dependence of the effective kinematic viscosity of turbulent He II, nu(eff)(T) , is deduced from second sound attenuation data using the late stage of decay of thermally induced counterflow He II turbulence in two channels of square cross section. It is shown to qualitatively agree with the published data for nu(eff)(T) calculated based on experiments on decaying-grid-generated He II turbulence [Niemela, J. Low Temp. Phys. 138, 537 (2005)]. Corrections to these data due to the "sine squared" law that describes attenuation of the second sound wave propagating along an arbitrary direction with respect to the direction of the core of a quantized vortex in turbulent He II are discussed and applied. PMID:17930181

Chagovets, T V; Gordeev, A V; Skrbek, L

2007-08-01

393

Effective kinematic viscosity of turbulent He II  

SciTech Connect

The temperature dependence of the effective kinematic viscosity of turbulent He II, {nu}{sub eff}(T), is deduced from second sound attenuation data using the late stage of decay of thermally induced counterflow He II turbulence in two channels of square cross section. It is shown to qualitatively agree with the published data for {nu}{sub eff}(T) calculated based on experiments on decaying-grid-generated He II turbulence [Niemela et al., J. Low Temp. Phys. 138, 537 (2005)]. Corrections to these data due to the 'sine squared' law that describes attenuation of the second sound wave propagating along an arbitrary direction with respect to the direction of the core of a quantized vortex in turbulent He II are discussed and applied.

Chagovets, T. V.; Gordeev, A. V. [Institute of Physics ASCR, v.v.i., Na Slovance 2, 182 21 Prague (Czech Republic); Skrbek, L. [Faculty of Mathematics and Physics, Charles University, V Holesovickach 2, 180 00 Prague (Czech Republic)

2007-08-15

394

Effective particle kinematics from quantum gravity  

SciTech Connect

Particles propagating in de Sitter spacetime can be described by the topological BF SO(4,1) theory coupled to point charges. Gravitational interaction between them can be introduced by adding to the action a symmetry breaking term, which reduces the local gauge symmetry down to SO(3,1), and which can be treated as a perturbation. In this paper we focus solely on topological interactions which correspond to zeroth order in this perturbative expansion. We show that in this approximation the system is effectively described by the SO(4,1) Chern-Simons theory coupled to particles and living on the three-dimensional boundary of spacetime. Then, using Alekseev-Malkin construction we find the effective theory of particles kinematics. We show that the particles action contains standard kinetic terms and the deformation shows up in the presence of interaction terms. The strength of the interactions is proportional to deformation parameter, identified with Planck mass scale.

Kowalski-Glikman, Jerzy; Starodubtsev, Artem [Institute for Theoretical Physics, University of Wroclaw, Pl. Maxa Borna 9, Pl-50-204 Wroclaw (Poland); Centre de Physique Theorique de Luminy, F-13288 Marseille (France)

2008-10-15

395

Effective particle kinematics from Quantum Gravity  

E-print Network

Particles propagating in de Sitter spacetime can be described by the topological BF $\\SO(4,1)$ theory coupled to point charges. Gravitational interaction between them can be introduced by adding to the action a symmetry breaking term, which reduces the local gauge symmetry down to $\\SO(3,1)$, and which can be treated as a perturbation. In this paper we focus solely on topological interactions which corresponds to zeroth order in this perturbative expansion. We show that in this approximation the system is effectively described by the $\\SO(4,1)$ Chern-Simons theory coupled to particles and living on the 3 dimensional boundary of space-time. Then, using Alekseev--Malkin construction we find the effective theory of particles kinematics. We show that the particles action contains standard kinetic terms and the deformation shows up in the presence of interaction terms. The strength of the interactions is proportional to deformation parameter, identified with Planck mass scale.

Jerzy Kowalski-Glikman; Artem Starodubtsev

2008-08-19

396

Galaxy simulations: Kinematics and mock observations  

NASA Astrophysics Data System (ADS)

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

Moody, Christopher E.

397

A fun intro to 1D kinematics  

E-print Network

Intro-physics texts often start with: (i) time as an implicitly-global variable, and (ii) the mass-independent acceleration-due-to-gravity near earth's surface as given with no larger context. Here we use well-known ``traveler-kinematic'' relations which work regardless of speed to construct a brief story for beginning students about: (a) time as a local quantity like position that depends on ``which clock", (b) coordinate-acceleration as an approximation to the acceleration felt by a moving traveler, and (c) the geometric origin (hence mass-independence) of gravitational acceleration. The goal is to take global time off the table from square one for everyone, while tantalizing students interested in the subject with predictive equations in range of their math-background.

Fraundorf, P

2014-01-01

398

Kinematics of Visually-Guided Eye Movements  

PubMed Central

One of the hallmarks of an eye movement that follows Listing’s law is the half-angle rule that says that the angular velocity of the eye tilts by half the angle of eccentricity of the line of sight relative to primary eye position. Since all visually-guided eye movements in the regime of far viewing follow Listing’s law (with the head still and upright), the question about its origin is of considerable importance. Here, we provide theoretical and experimental evidence that Listing’s law results from a unique motor strategy that allows minimizing ocular torsion while smoothly tracking objects of interest along any path in visual space. The strategy consists in compounding conventional ocular rotations in meridian planes, that is in horizontal, vertical and oblique directions (which are all torsion-free) with small linear displacements of the eye in the frontal plane. Such compound rotation-displacements of the eye can explain the kinematic paradox that the fixation point may rotate in one plane while the eye rotates in other planes. Its unique signature is the half-angle law in the position domain, which means that the rotation plane of the eye tilts by half-the angle of gaze eccentricity. We show that this law does not readily generalize to the velocity domain of visually-guided eye movements because the angular eye velocity is the sum of two terms, one associated with rotations in meridian planes and one associated with displacements of the eye in the frontal plane. While the first term does not depend on eye position the second term does depend on eye position. We show that compounded rotation - displacements perfectly predict the average smooth kinematics of the eye during steady- state pursuit in both the position and velocity domain. PMID:24751602

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

2014-01-01

399

Inversion of the star transform  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

400

Optimization and geophysical inverse problems  

SciTech Connect

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

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

2000-10-01

401

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

SciTech Connect

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

Li, Chun-Xia; Gu, Guo-Ying; Yang, Mei-Ju; Zhu, Li-Min, E-mail: zhulm@sjtu.edu.cn [State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)] [State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

2013-12-15

402

Source Kinematics of the 3 November, 2002 Mw7.9 Denali Fault, Alaska Earthquake  

NASA Astrophysics Data System (ADS)

The kinematics of the rupture process of the November 3, 2002 Mw7.9 Denali earthquake is investigated. The epicenter of the event is located near the northern point of the curved Denali/Totschunda fault system. The first motion focal mechanism indicates the event initiated as a southwest striking reverse event on the Susitna Glacier Fault apparently triggering 300 km of predominantly strike-slip rupture to the east on the Denali and Totschunda faults. We parameterized this complex fault geometry as a four-segment fault model allowing for variable slip direction (rake) with a constant dislocation rise time (3 seconds) and rupture velocity (3 km/s). Ground deformation from 17 continuous GPS sites of the Alaska Deformation Array, surface displacements provided by the Denali Earthquake Geologic Field Team, and displacement seismograms from 6 strong motion stations operated by the Geophysical Institute and the USGS were inverted to obtain a kinematic model of the rupture process. The average slip, peak slip, and total seismic moment were found to be 1.69 m, 12.4 m, and 6.98e20 Nm, respectively. The kinematic inversion indicates that the event initiated on the Susitna Glacier reverse fault (strike=262, dip=48) with an Mw=6.8. The strike-slip slip is concentrated in asperities located between 50 to 100 km, and 140 to 230 km ESE of the epicenter, and comprises the majority of the moment release, although the total length of the rupture is approximately 300 km. We will update the model by incorporating campaign GPS deformation data, and displacements derived from strong motion acceleration records at sites located along the Alyeska Pipeline. In addition, the results of a source parameter sensitivity analysis will be presented.

Dreger, D.; Ratchkovski, N.; Hansen, R.

2003-04-01

403

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

PubMed

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

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

2013-12-01

404

A submillimetre survey of the kinematics of the Perseus molecular cloud - III. Clump kinematics  

Microsoft Academic Search

We explore the kinematic properties of dense continuum clumps in the Perseus molecular cloud, derived from our wide-field C18O J = 3 --> 2 data across four regions - NGC 1333, IC 348\\/HH 211, L1448 and L1455. Two distinct populations are examined, identified using the automated algorithms CLFIND (85 clumps) and GAUSSCLUMPS (122 clumps) on existing SCUBA 850-mum data. These

Emily I. Curtis; John S. Richer

2011-01-01

405

The relationship between gluteal muscle activation and throwing kinematics in baseball and softball catchers.  

PubMed

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. PMID:23591952

Plummer, Hillary A; Oliver, Gretchen D

2014-01-01

406

Population inversion by chirped pulses  

SciTech Connect

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.

Lu Tianshi [Department of Mathematics and Statistics, Wichita State University, Wichita, Kansas 67260-0033 (United States)

2011-09-15

407

Frequency-wavenumber domain phase inversion along reflection wavepaths  

NASA Astrophysics Data System (ADS)

A background velocity model containing the correct low-wavenumber information is desired for both the quality of the migration image and the success of waveform inversion. To achieve this goal, the velocity is updated along the reflection wavepaths, rather than along both the reflection ellipses and transmission wavepaths as in conventional FWI. This method allows for reconstructing the low-wavenumber part of the background velocity model, even in the absence of long offsets and low-frequency component of the data. Moreover, in gradient-based iterative updates, instead of forming the data error conventionally, we propose to exploit the phase mismatch between the observed and the calculated data. The phase mismatch emphasizes a kinematic error and varies quasi-linearly with respect to the velocity error. The phase mismatch is computed (1) in the frequency-wavenumber (f-k) domain replacing the magnitudes of the calculated common shot gather by those of the observed one, and (2) in the temporal-spatial domain to form the difference between the transformed calculated common-shot gather and the observed one. The background velocity model inverted according to the proposed methods can serve as an improved initial velocity model for conventional waveform inversion. Tests with synthetic and field data show both the benefits and limitations of this method.

Yu, Han; Huang, Yunsong

2014-12-01

408

Adjoint modeling for acoustic inversion.  

PubMed

The use of adjoint modeling for acoustic inversion is investigated. An adjoint model is derived from a linearized forward propagation model to propagate data-model misfit at the observation points back through the medium to the medium perturbations not being accounted for in the model. This adjoint model can be used to aid in inverting for these unaccounted medium perturbations. Adjoint methods are being applied to a variety of inversion problems, but have not drawn much attention from the underwater acoustic community. This paper presents an application of adjoint methods to acoustic inversion. Inversions are demonstrated in simulation for both range-independent and range-dependent sound speed profiles using the adjoint of a parabolic equation model. Sensitivity and error analyses are discussed showing how the adjoint model enables calculations to be performed in the space of observations, rather than the often much larger space of model parameters. Using an adjoint model enables directions of steepest descent in the model parameters (what we invert for) to be calculated using far fewer modeling runs than if a forward model only were used. PMID:15000173

Hursky, Paul; Porter, Michael B; Cornuelle, B D; Hodgkiss, W S; Kuperman, W A

2004-02-01

409

Lightcurves for Inversion Model Candidates  

NASA Astrophysics Data System (ADS)

We present lightcurves for four inversion model candidate asteroids that will benefit from additional data at another phase angle bisector phase angle. We obtained synodic periods for each asteroid that were within ±0.002 h. Most have lightcurves that differed from previously published lightcurves in both amplitude and shape.

Klinglesmith, Daniel A., III; Hanowell, Jesse; Warren, Curtis Alan

2014-10-01

410

Inverse Problems and Industrial Mathematics  

E-print Network

). Depending on the mode of operation and of the chemical analysis of the iron ore, roughly 7 mio tons of CO2 in process parameters - charging strategy (distribution of coke-ore layers) - different raw materials Inverse Problems and Industrial Mathematics 8 MathConsult GmbH - different raw materials - day production

Fulmek, Markus

411

Lightcurves for Inversion Model Candidates  

NASA Astrophysics Data System (ADS)

We present lightcurves for 12 inversion model candidate asteroids that will benefit from additional data at another solar bisector phase angle. We obtained synodic periods for each asteroid that were within ± 0.002 h. Most have shapes that differed from previously published lightcurves in both amplitude and shape.

Klinglesmith, Daniel A., III; Hanowell, Jesse; Risley, Ethan; Turk, Janek; Vargas, Angelica; Warren, Curtis Alan

2014-07-01

412

Action understanding as inverse planning  

Microsoft Academic Search

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 principle of rationality: the expectation that agents will plan approximately rationally

Chris L. Baker; Rebecca Saxe; Joshua B. Tenenbaum

2009-01-01

413

Wing kinematics in a hovering dronefly minimize power expenditure.  

PubMed

When an insect hovers or performs constant-speed flight, its wings flap at certain amplitude, frequency, angle of attack, etc., and the flight is balanced (vertical force equals to the weight, and horizontal force and pitch moment are zero). It is possible that when some other sets of values of wing kinematical parameters are used, the force and moment balance conditions can still be satisfied. Does the wing kinematics used by a constant-speed flying insect minimize the power expenditure? In this study, whether the wing kinematics used by a freely hovering dronefly minimizes its energy expenditure was investigated. First, the power consumption using the set of values of wing kinematical parameters that was actually employed by the insect was computed. Then, the kinematical parameters were changed while keeping the equilibrium flight conditions satisfied, and the power consumption was recalculated. It was found that wing kinematical parameters used by the freely hovering dronefly are very close to that minimize its energy consumption, and they can ensure the margin of controllability from hovering to maneuvers. That is, slight change of wing kinematical parameters did not cause significant change of the specific power (maintained a relatively small value). PMID:25347844

Wu, J H; Sun, M

2014-01-01

414

Multidimensional finite difference electromagnetic modeling and inversion based on the balance method  

NASA Astrophysics Data System (ADS)

A new approach for multisource three-dimensional (3-D) finite-difference (FD) electromagnetic (EM) modeling in the frequency domain is introduced. This approach is based on the balance method, solves for the anomalous electric field and automatically takes into account the conservation law of Maxwell's equations. Also a new Dirichlet boundary condition, based on the quasi-analytical (QA) approximation/series, is proposed to truncate the FD modeling grid significantly without notable loss of computational accuracy. The developed 3-D FD modeling code can be used in different geophysical applications including magnetotelluric (MT), controlled source magnetotelluric (CSMT), airborne, and borehole EM methods in the frequency domain. The modeling results obtained by the new algorithm demonstrated good agreement with the respective integral equation solutions. Regularization methods search for a smooth or focused class of the geoelectrical models to invert for. The traditional approach has been to use smooth models to describe the conductivity distribution in the subsurface formations. A new method for two-dimensional (2-D) MT focusing inversion is developed. It approximates the conductivity distribution by models with blocky (focused) conductivity structures. The class (smooth or focused) of inverse models is chosen based on the objective of the survey and available geological information, and can be determined from inversion by selecting the corresponding stabilizing functional in the regularized objective functional subjected to minimization. This new method was applied to synthetic MT data, and MT field data collected for crustal imaging in Carrizo Plain, California and for mining exploration in Voisey's Bay, Canada. A novel algorithm for 3-D EM iterative migration is introduced. It does not require Frechet (Jacobian) matrix computation but rather the conjugate of Frechet matrix acting on the residual field using just one forward modeling run. This algorithm utilizes the 3-D FD method described above and the regularized conjugate gradient (RCG) scheme. In the framework of this approach, the 3-D FD forward modeling solution is computed three times per frequency in each iteration step. In the first forward solution, the FD forward operator is applied to compute the predicted field for a given conductivity distribution. The residual field is then computed by taking the difference between the observed and predicted data. In the second forward solution, the FD operator is utilized to migrate the residual field in the lower half-space using the adjoint operator. In the third forward solution, the FD operator is used to compute the optimal step of minimization. The practical effectiveness of the newly developed 3-D FD inversion technique is illustrated by inverting both synthetic data and field data of Voisey's Bay like geoelectrical model.

Mehanee, Salah Abdelraheem

415

The Indian monsoon speeds up plate kinematics.  

NASA Astrophysics Data System (ADS)

The convergence of the Indian plate towards Eurasia is faster on the eastern side of the Himalayas by ~ 10 mm yr-1 than on the western side. The Carlsberg ridge records the motion of the Indian plate with respect to Africa, which moves very slowly with respect to Eurasia. Consistently, spreading rates are faster on the eastern side of the ridge. This situation has not remained for ever; available data indicate that the Carlsberg ridge spread at a uniform rate between 20 and 11 Ma, only afterwards did the spreading pattern become more complex. The onset of the Indian monsoon, at ~8 Ma, could be responsible for the rotational convergence of India towards Eurasia and spreading of the Carlsberg ridge, by the action of two joint mechanisms. The very active erosion lowered the bhutanese Himalayas with respect the nepalese Himalayas to a new morphologic equilibrium between tectonics and climate. First, volume balance suggests that the fast eastern erosion "consumes" more Indian crust than the slower western erosion and pumps the Indian lithosphere at mean horizontal velocity of 3 to 5 mm yr-1, i.e. only less than half the velocity increase along the Himalayan arc. The missing term is found in plate kinematics. The post-monsoon force balance requires a faster deformation and larger viscous stresses to compensate the deficit in gravitational potential energy (GPE) associated to the new eastern morphology. Far-field driving forces are less balanced by a lower mountain belt and plate kinematics subsequently accelerate. The Carlsberg-India-Himalyas system can therefore be regarded as a system in which extensional stresses from the ridge are unevenly resisted by the Himalayan load that varies through time and space. Not only does the monsoon affect the topography but it also boosts the convergence in the eastern Himalayas and spreading of the SE side of the Carlsberg ridge. Pairs of convergence rates and GPE can be extracted and ultimately allow one to estimate an effective viscosity for the lithosphere of ~1022 Pa s with no need to quantify the driving tectonic forces.

Husson, L.

2008-12-01

416

The [N II] Kinematics of R Aquarii  

NASA Technical Reports Server (NTRS)

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.

Hollis, J. M.; Vogel, S. N.; VanBuren, D.; Strong, J. P.; Lyon, R. G.; Dorband, J. E.

1998-01-01

417

Kinematic and Thermal Control of Vortex Breakdown  

NASA Astrophysics Data System (ADS)

It is shown that a combination of additional near-axis swirl and temperature gradients can efficiently control vortex breakdown (VB). The numerical analysis of a flow in a cylindrical container driven by a rotating bottom disk reveals the underlying mechanisms of such kinematic and thermal control. The analysis explains experimentally observed effects of control co- and counter-rotation with no temperature gradient (Husain et.al. 2003, Phys. Fluids, 15, 271) and reveals some flaws of dye visualization. Co- (counter-) rotation diminishes (enhances) the unfavorable axial gradients of pressure and thus suppresses (stimulates) VB. An important new feature found is that a moderate negative (positive) axial gradient of temperature induces a control meridional co-(counter-) flow, which enforces the effects of the additional swirl, e.g., significantly enforce (diminish) the VB enhancement by the counter-rotation. A strong positive temperature gradient stimulates the centrifugal instability and induces time oscillations in the flow with counter-rotation. These results indicate that an additional co-rotating cold (counter-rotating hot) swirling jet can help to suppress (enhance) VB in practical flows, e.g. over delta-wing aircraft and vortex burners.

Herrada, Miguel A.; Shtern, Vladimir

2003-11-01

418

Learning Kinematic Constraints in Laparoscopic Surgery  

PubMed Central

To better understand how kinematic variables impact learning in surgical training, we devised an interactive environment for simulated laparoscopic maneuvers, using either 1) mechanical constraints typical of a surgical “box-trainer” or 2) virtual constraints in which free hand movements control virtual tool motion. During training, the virtual tool responded to the absolute position in space (Position-Based) or the orientation (Orientation-Based) of a hand-held sensor. Volunteers were further assigned to different sequences of target distances (Near-Far-Near or Far-Near-Far). Training with the Orientation-Based constraint enabled much lower path error and shorter movement times during training, which suggests that tool motion that simply mirrors joint motion is easier to learn. When evaluated in physically constrained (physical box-trainer) conditions, each group exhibited improved performance from training. However, Position-Based training enabled greater reductions in movement error relative to Orientation-Based (mean difference: 14.0 percent; CI: 0.7, 28.6). Furthermore, the Near-Far-Near schedule allowed a greater decrease in task time relative to the Far-Near-Far sequence (mean ?13:5 percent, CI: ?19:5, ?7:5). Training that focused on shallow tool insertion (near targets) might promote more efficient movement strategies by emphasizing the curvature of tool motion. In addition, our findings suggest that an understanding of absolute tool position is critical to coping with mechanical interactions between the tool and trocar. PMID:23293709

Huang, Felix C.; Mussa-Ivaldi, Ferdinando A.; Pugh, Carla M.; Patton, James L.

2012-01-01

419

Stellar kinematics in the local disk  

NASA Astrophysics Data System (ADS)

From Hipparcos distances and proper motions for approximately 22000 stars we described the residual velocity distribution by the superposition of two Gaussians instead one as traditionally used. The sample of stars was selected by magnitude, color, Galactic position and distance and ranged in 6 spectral-type groups, 3 of early-type and 3 of late-type stars. We verified that for the early-type stars no gain is attained with our representation but for the late-type stars it is clear that the superposition of two Gaussians better describe the velocity distribution. Our results clearly point to the existence of two different kinematic populations very well characterized in the three late-type star groups: one population with high velocity dispersion and another with low velocity dispersion. It is still more interesting since the high and the low velocity dispersion population is the same in all the three groups. The core of this work was published in De Souza & Teixeira 2007.

Teixeira, R.; de Souza, R. E.; Dos Anjos, S.

2008-12-01

420

Kinematic analysis of rope skipper's stability  

NASA Astrophysics Data System (ADS)

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.

Ab Ghani, Nor Atikah; Rambely, Azmin Sham

2014-06-01

421

Global H I Kinematics in Dwarf Galaxies  

NASA Astrophysics Data System (ADS)

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 (~6-10 km s-1) with higher-velocity wings to either side that contain ~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 lang?H I rang. 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.

Stilp, Adrienne M.; Dalcanton, Julianne J.; Warren, Steven R.; Skillman, Evan; Ott, Jürgen; Koribalski, Bärbel

2013-03-01

422

Morphology and kinematics in clusters of galaxies  

NASA Technical Reports Server (NTRS)

The existence of subclustering, infall, and the morphology-local density relation suggest that there should be differences in the kinematics of different morphological populations in clusters. From published data, we compile a sample of galaxy redshifts and types in six rich clusters of galaxies: A548, A1060, A1644, A1656, A2l51, and DC 2048 - 52. In three clusters, the velocity distribution of spiral galaxies is different from those of other morphological populations: (1) spirals and ellipticals differ in A1656 and A2151, and (2) spirals and S0s differ in DC 2048 - 52. The differences in the distributions result primarily from differences in the mean velocities. The results are consistent with a picture in which a cluster irregularly accretes clumps of mostly spiral galaxies from the field, causing the combined velocity distribution to be asymmetric. These clumps might infall within the plane of a wall like the Great Wall of galaxies. Recent dynamical simulations show that the asymmetries may persist until after the clumps have merged with the central mass concentration.

Zabludoff, Ann I.; Franx, Marijn

1993-01-01

423

Kinematic mental simulations in abduction and deduction  

PubMed Central

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

Khemlani, Sangeet Suresh; Mackiewicz, Robert; Bucciarelli, Monica; Johnson-Laird, Philip N.

2013-01-01

424

Thermally Insulating, Kinematic Tensioned-Fiber Suspension  

NASA Technical Reports Server (NTRS)

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.

Voellmer, George M.

2004-01-01

425

GLOBAL H I KINEMATICS IN DWARF GALAXIES  

SciTech Connect

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.

Stilp, Adrienne M.; Dalcanton, Julianne J. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Warren, Steven R.; Skillman, Evan [Minnesota Institute for Astrophysics, University of Minnesota, 116 Church St. SE, Minneapolis, MN 55455 (United States); Ott, Juergen [National Radio Astronomy Observatory, P.O. Box O, 1003 Lopezville Road, Socorro, NM 87801 (United States); Koribalski, Baerbel [Australia Telescope National Facility, CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 (Australia)

2013-03-10

426

An internal model of head kinematics predicts the influence of head orientation on reflexive eye movements  

NASA Astrophysics Data System (ADS)

Our sense of self-motion and self-orientation results from combining information from different sources. We hypothesize that the central nervous system (CNS) uses internal models of the laws of physics to merge cues provided by different sensory systems. Different models that include internal models have been proposed; we focus herein on that referred to as the sensory weighting model (Zupan et al 2002 Biol. Cybern. 86 209-30). For simplicity, we isolate the portion of the sensory weighting model that estimates head angular velocity: it includes an inverse internal model of head kinematics and an 'idiotropic' vector aligned with the main body axis. Following a post-rotatory tilt in the dark, which is a rapid tilt following a constant-velocity rotation about an earth-vertical axis, the inverse internal model is applied to conflicting vestibular signals. Consequently, the CNS computes an inaccurate estimate of head angular velocity that shifts toward alignment with an estimate of gravity. Since reflexive eye movements known as vestibulo-ocular reflexes (VOR) compensate for this estimate of head angular velocity, the model predicts that the VOR rotation axis shifts toward alignment with this estimate of gravity and that the VOR time constant depends on final head orientation. These predictions are consistent with experimental data.

Zupan, L. H.; Merfeld, D. M.

2005-09-01

427

A submillimetre survey of the kinematics of the Perseus molecular cloud - III. Clump kinematics  

Microsoft Academic Search

We explore the kinematics of continuum clumps in the Perseus molecular cloud,\\u000aderived from C18O J=3-2 data. Two populations are examined, identified using\\u000athe automated algorithms CLFIND and GAUSSCLUMPS on existing SCUBA data. The\\u000aclumps have supersonic linewidths with distributions which suggest the C18O\\u000aline probes a lower-density 'envelope' rather than a dense inner core. Similar\\u000alinewidth distributions for protostellar

Emily I. Curtis; John S. Richer

2010-01-01

428

Knee's Motion Path Relative to the Passive Coupled Kinematic Envelope  

E-print Network

Laxity assessments are done before, during, and after intervention of knee injuries to assess potential outcomes. Study objectives were to create a method to define the passive kinematic limits, without artificially constraining coupled motion...

Dodd, Kevin A.

2009-06-15

429

Kinematic Tolerance and the Topology of Configuration Space Ernest Davis  

E-print Network

and suggestions; also to Dana Angluin, Mladen Covic, Philip Davis, Drew McDermott, Bud Mishra, Igor Najfeld, SteveKinematic Tolerance and the Topology of Configuration Space Ernest Davis New York University 251

Davis, Ernest

430

PERIORAL BIOMECHANICS, KINEMATICS, AND ELECTROPHYSIOLOGY IN PARKINSON'S DISEASE  

E-print Network

This investigation quantitatively characterized the orofacial biomechanics, labial kinematics, and associated electromyography (EMG) patterns in individuals with Parkinson's disease (PD) as a function of anti-PD medication state. Passive perioral...

Chu, Shin Ying

2010-11-21

431

Kinematic Treatment of CME Evolution in the Solar Wind.  

National Technical Information Service (NTIS)

We present a kinematic study of the evolution of coronal mass ejections (CMEs) in the solar wind. Specifically, we consider the effects of: (1) spherical expansion; and (2) uniform expansion due to pressure gradients between the Interplanetary CME (ICME) ...

P. Riley, N. U. Crooker