The influence of external perturbations on running kinematics and muscle activity before and after accommodation.

Science.gov (United States)

Haudum, Anita; Birklbauer, Jürgen; Müller, Erich

2012-01-01

In the current study, the running pattern of the lower extremity was examined while being perturbed through tubes attached between the ankles and the lower back to analyze influences on the running pattern variability before and after a varied running intervention. 3D-kinematics, joint coupling and electromyography (EMG), as well as their variability, were analyzed in ten healthy male participants during treadmill running (10.5 km·h(-1)). Pre- and post-tests each consisted of 2 x 30 min treadmill running (one with and one without tubes). The results showed major acute effects on EMG and kinematics, as well as joint coordination variability, due to the constraints (p running below normal running level (p constraint serves to acutely increase variability, but may lead to reduced variability when applied for a longer period of time.

Geometrically constrained kinematic global navigation satellite systems positioning: Implementation and performance

Science.gov (United States)

Asgari, Jamal; Mohammadloo, Tannaz H.; Amiri-Simkooei, Ali Reza

2015-09-01

GNSS kinematic techniques are capable of providing precise coordinates in extremely short observation time-span. These methods usually determine the coordinates of an unknown station with respect to a reference one. To enhance the precision, accuracy, reliability and integrity of the estimated unknown parameters, GNSS kinematic equations are to be augmented by possible constraints. Such constraints could be derived from the geometric relation of the receiver positions in motion. This contribution presents the formulation of the constrained kinematic global navigation satellite systems positioning. Constraints effectively restrict the definition domain of the unknown parameters from the three-dimensional space to a subspace defined by the equation of motion. To test the concept of the constrained kinematic positioning method, the equation of a circle is employed as a constraint. A device capable of moving on a circle was made and the observations from 11 positions on the circle were analyzed. Relative positioning was conducted by considering the center of the circle as the reference station. The equation of the receiver's motion was rewritten in the ECEF coordinates system. A special attention is drawn onto how a constraint is applied to kinematic positioning. Implementing the constraint in the positioning process provides much more precise results compared to the unconstrained case. This has been verified based on the results obtained from the covariance matrix of the estimated parameters and the empirical results using kinematic positioning samples as well. The theoretical standard deviations of the horizontal components are reduced by a factor ranging from 1.24 to 2.64. The improvement on the empirical standard deviation of the horizontal components ranges from 1.08 to 2.2.

CLASH-VLT: constraints on f (R) gravity models with galaxy clusters using lensing and kinematic analyses

Energy Technology Data Exchange (ETDEWEB)

Pizzuti, L.; Sartoris, B.; Borgani, S.; Girardi, M., E-mail: pizzuti@oats.inaf.it, E-mail: sartoris@oats.inaf.it, E-mail: borgani@oats.inaf.it, E-mail: girardi@oats.inaf.it [Dipartimento di Fisica, Sezione di Astronomia, Università di Trieste, Via Tiepolo 11, I-34143 Trieste (Italy); and others

2017-07-01

We perform a maximum likelihood kinematic analysis of the two dynamically relaxed galaxy clusters MACS J1206.2-0847 at z =0.44 and RXC J2248.7-4431 at z =0.35 to determine the total mass profile in modified gravity models, using a modified version of the MAMPOSSt code of Mamon, Biviano and Bou and apos;e. Our work is based on the kinematic and lensing mass profiles derived using the data from the Cluster Lensing And Supernova survey with Hubble (hereafter CLASH) and the spectroscopic follow-up with the Very Large Telescope (hereafter CLASH-VLT). We assume a spherical Navarro-Frenk-White (NFW hereafter) profile in order to obtain a constraint on the fifth force interaction range λ for models in which the dependence of this parameter on the environment is negligible at the scale considered (i.e. λ= const ) and fixing the fifth force strength to the value predicted in f (R) gravity. We then use information from lensing analysis to put a prior on the other NFW free parameters. In the case of MACSJ 1206 the joint kinematic+lensing analysis leads to an upper limit on the effective interaction range λ≤1.61 mpc at Δχ{sup 2}=2.71 on the marginalized distribution. For RXJ 2248 instead a possible tension with the ΛCDM model appears when adding lensing information, with a lower limit λ≥0.14 mpc at Δχ{sup 2}=2.71. This is consequence of the slight difference between the lensing and kinematic data, appearing in GR for this cluster, that could in principle be explained in terms of modifications of gravity. We discuss the impact of systematics and the limits of our analysis as well as future improvements of the results obtained. This work has interesting implications in view of upcoming and future large imaging and spectroscopic surveys, that will deliver lensing and kinematic mass reconstruction for a large number of galaxy clusters.

The Impact of the Support System’s Kinematic Structure on Selected Kinematic and Dynamic Quantities of an Experimental Crane

Directory of Open Access Journals (Sweden)

Trąbka Arkadiusz

2014-12-01

Full Text Available This paper presents a comparative analysis of two kinematic structures of the support system (with supports with bilateral and unilateral constraints, which were used in an experimental model of a crane. The computational model was developed by using the ADAMS software. The impact of the kinematic structure of the support system on selected kinematic and dynamic values that were recorded during the slewing motion was analysed. It was found, among other things, that an increased number of degrees of freedom of the support system leads to multiple distortions of time characteristics of kinematic and dynamic quantities.

Effects of load on good morning kinematics and EMG activity

Directory of Open Access Journals (Sweden)

Andrew David Vigotsky

2015-01-01

Full Text Available Many strength and conditioning coaches utilize the good morning (GM to strengthen the hamstrings and spinal erectors. However, little research exists on its electromyography (EMG activity and kinematics, and how these variables change as a function of load. The purpose of this investigation was to examine how estimated hamstring length, integrated EMG (IEMG activity of the hamstrings and spinal erectors, and kinematics of the lumbar spine, hip, knee, and ankle are affected by changes in load. Fifteen trained male participants (age = 24.6 ± 5.3 years; body mass = 84.7 ± 11.3 kg; height = 180.9 ± 6.8 cm were recruited for this study. Participants performed five sets of the GM, utilizing 50, 60, 70, 80, and 90% of one-repetition maximum (1RM in a randomized fashion. IEMG activity of hamstrings and spinal erectors tended to increase with load. Knee flexion increased with load on all trials. Estimated hamstring length decreased with load. However, lumbar flexion, hip flexion, and plantar flexion experienced no remarkable changes between trials. These data provide insight as to how changing the load of the GM affects EMG activity, kinematic variables, and estimated hamstring length. Implications for hamstring injury prevention are discussed. More research is needed for further insight as to how load affects EMG activity and kinematics of other exercises.

Kinematics and dynamics analysis of a novel serial-parallel dynamic simulator

Energy Technology Data Exchange (ETDEWEB)

Hu, Bo; Zhang, Lian Dong; Yu, Jingjing [Parallel Robot and Mechatronic System Laboratory of Hebei Province, Yanshan University, Qinhuangdao, Hebei (China)

2016-11-15

A serial-parallel dynamics simulator based on serial-parallel manipulator is proposed. According to the dynamics simulator motion requirement, the proposed serial-parallel dynamics simulator formed by 3-RRS (active revolute joint-revolute joint-spherical joint) and 3-SPR (Spherical joint-active prismatic joint-revolute joint) PMs adopts the outer and inner layout. By integrating the kinematics, constraint and coupling information of the 3-RRS and 3-SPR PMs into the serial-parallel manipulator, the inverse Jacobian matrix, velocity, and acceleration of the serial-parallel dynamics simulator are studied. Based on the principle of virtual work and the kinematics model, the inverse dynamic model is established. Finally, the workspace of the (3-RRS)+(3-SPR) dynamics simulator is constructed.

Kinematics and dynamics analysis of a novel serial-parallel dynamic simulator

International Nuclear Information System (INIS)

Hu, Bo; Zhang, Lian Dong; Yu, Jingjing

2016-01-01

A serial-parallel dynamics simulator based on serial-parallel manipulator is proposed. According to the dynamics simulator motion requirement, the proposed serial-parallel dynamics simulator formed by 3-RRS (active revolute joint-revolute joint-spherical joint) and 3-SPR (Spherical joint-active prismatic joint-revolute joint) PMs adopts the outer and inner layout. By integrating the kinematics, constraint and coupling information of the 3-RRS and 3-SPR PMs into the serial-parallel manipulator, the inverse Jacobian matrix, velocity, and acceleration of the serial-parallel dynamics simulator are studied. Based on the principle of virtual work and the kinematics model, the inverse dynamic model is established. Finally, the workspace of the (3-RRS)+(3-SPR) dynamics simulator is constructed

Global-local optimization of flapping kinematics in hovering flight

KAUST Repository

Ghommem, Mehdi; Hajj, M. R.; Mook, Dean T.; Stanford, Bret K.; Bé ran, Philip S.; Watson, Layne T.

2013-01-01

The kinematics of a hovering wing are optimized by combining the 2-d unsteady vortex lattice method with a hybrid of global and local optimization algorithms. The objective is to minimize the required aerodynamic power under a lift constraint. The hybrid optimization is used to efficiently navigate the complex design space due to wing-wake interference present in hovering aerodynamics. The flapping wing is chosen so that its chord length and flapping frequency match the morphological and flight properties of two insects with different masses. The results suggest that imposing a delay between the different oscillatory motions defining the flapping kinematics, and controlling the way through which the wing rotates at the end of each half stroke can improve aerodynamic power under a lift constraint. Furthermore, our optimization analysis identified optimal kinematics that agree fairly well with observed insect kinematics, as well as previously published numerical results.

Global-local optimization of flapping kinematics in hovering flight

KAUST Repository

Ghommem, Mehdi

2013-06-01

The kinematics of a hovering wing are optimized by combining the 2-d unsteady vortex lattice method with a hybrid of global and local optimization algorithms. The objective is to minimize the required aerodynamic power under a lift constraint. The hybrid optimization is used to efficiently navigate the complex design space due to wing-wake interference present in hovering aerodynamics. The flapping wing is chosen so that its chord length and flapping frequency match the morphological and flight properties of two insects with different masses. The results suggest that imposing a delay between the different oscillatory motions defining the flapping kinematics, and controlling the way through which the wing rotates at the end of each half stroke can improve aerodynamic power under a lift constraint. Furthermore, our optimization analysis identified optimal kinematics that agree fairly well with observed insect kinematics, as well as previously published numerical results.

Tibial rotation kinematics subsequent to knee arthroplasty

Science.gov (United States)

Collins, Duane J.; Khatib, Yasser H.; Parker, David A.; Jenkin, Deanne E.; Molnar, Robert B.

2015-01-01

Background The use of computer assisted joint replacement has facilitated precise intraoperative measurement of knee kinematics. The changes in “screw home mechanism” (SHM) resulting from Total Knee Arthroplasty (TKA) with different prostheses and constraints has not yet been accurately described. Methods A pilot study was first completed. Intraoperative kinematic data was collected two groups of 15 patients receiving different prostheses. Results On average, patients lost 5.3° of ER (SD = 6.1°). There was no significant difference between the prostheses or different prosthetic constraints. Conclusions There significant loss of SHM after TKA. Further research is required to understand its impact on patient function. PMID:25829754

Freedom and constraint analysis and optimization

NARCIS (Netherlands)

Brouwer, Dannis Michel; Boer, Steven; Aarts, Ronald G.K.M.; Meijaard, Jacob Philippus; Jonker, Jan B.

2011-01-01

Many mathematical and intuitive methods for constraint analysis of mechanisms have been proposed. In this article we compare three methods. Method one is based on Grüblers equation. Method two uses an intuitive analysis method based on opening kinematic loops and evaluating the constraints at the

Dynamics and causality constraints

International Nuclear Information System (INIS)

Sousa, Manoelito M. de

2001-04-01

The physical meaning and the geometrical interpretation of causality implementation in classical field theories are discussed. Causality in field theory are kinematical constraints dynamically implemented via solutions of the field equation, but in a limit of zero-distance from the field sources part of these constraints carries a dynamical content that explains old problems of classical electrodynamics away with deep implications to the nature of physicals interactions. (author)

Alterations in knee kinematics after partial medial meniscectomy are activity dependent.

Science.gov (United States)

Edd, Shannon N; Netravali, Nathan A; Favre, Julien; Giori, Nicholas J; Andriacchi, Thomas P

2015-06-01

Alterations in knee kinematics after partial meniscectomy have been linked to the increased risk of osteoarthritis in this population. Understanding differences in kinematics during static versus dynamic activities of increased demand can provide important information regarding the possible underlying mechanisms of these alterations. Differences in the following 2 kinematics measures will increase with activity demand: (1) the offset toward external tibial rotation for the meniscectomized limb compared with the contralateral limb during stance and (2) the difference in knee flexion angle at initial foot contact between the meniscectomized and contralateral limbs. Controlled laboratory study. This study compared side-to-side differences in knee flexion and rotation angles during static and dynamic activities. Thirteen patients (2 female) were tested in a motion capture laboratory at 6 ± 2 months after unilateral, arthroscopic, partial medial meniscectomy during a static reference pose and during 3 dynamic activities: walking, stair ascent, and stair descent. The meniscectomized limb demonstrated more external tibial rotation compared with the contralateral limb during dynamic activities, and there was a trend that this offset increased with activity demand (repeated-measures analysis of variance [ANOVA] for activity, P = .07; mean limb difference: static pose, -0.1° ± 3.3°, P = .5; walking, 1.2° ± 3.8°, P = .1; stair ascent, 2.0° ± 3.2°, P = .02; stair descent, 3.0° ± 3.5°, P = .005). Similarly, the meniscectomized knee was more flexed at initial contact than the contralateral limb during dynamic activities (repeated-measures ANOVA for activity P = .006; mean limb difference: reference pose, 1.0° ± 2.5°, P = .09; walking, 2.0° ± 3.9°, P = .05; stair ascent, 5.9° ± 5.3°, P = .009; stair descent, 3.5° ± 4.0°, P = .004). These results suggest both a structural element and a potential muscular element for the differences in kinematics after

Efficient dynamic modeling of manipulators containing closed kinematic loops

Science.gov (United States)

Ferretti, Gianni; Rocco, Paolo

An approach to efficiently solve the forward dynamics problem for manipulators containing closed chains is proposed. The two main distinctive features of this approach are: the dynamics of the equivalent open loop tree structures (any closed loop can be in general modeled by imposing some additional kinematic constraints to a suitable tree structure) is computed through an efficient Newton Euler formulation; the constraint equations relative to the most commonly adopted closed chains in industrial manipulators are explicitly solved, thus, overcoming the redundancy of Lagrange's multipliers method while avoiding the inefficiency due to a numerical solution of the implicit constraint equations. The constraint equations considered for an explicit solution are those imposed by articulated gear mechanisms and planar closed chains (pantograph type structures). Articulated gear mechanisms are actually used in all industrial robots to transmit motion from actuators to links, while planar closed chains are usefully employed to increase the stiffness of the manipulators and their load capacity, as well to reduce the kinematic coupling of joint axes. The accuracy and the efficiency of the proposed approach are shown through a simulation test.

Is Active Tectonics on Madagascar Consistent with Somalian Plate Kinematics?

Science.gov (United States)

Stamps, D. S.; Kreemer, C.; Rajaonarison, T. A.

2017-12-01

The East African Rift System (EARS) actively breaks apart the Nubian and Somalian tectonic plates. Madagascar finds itself at the easternmost boundary of the EARS, between the Rovuma block, Lwandle plate, and the Somalian plate. Earthquake focal mechanisms and N-S oriented fault structures on the continental island suggest that Madagascar is experiencing east-west oriented extension. However, some previous plate kinematic studies indicate minor compressional strains across Madagascar. This inconsistency may be due to uncertainties in Somalian plate rotation. Past estimates of the rotation of the Somalian plate suffered from a poor coverage of GPS stations, but some important new stations are now available for a re-evaluation. In this work, we revise the kinematics of the Somalian plate. We first calculate a new GPS velocity solution and perform block kinematic modeling to evaluate the Somalian plate rotation. We then estimate new Somalia-Rovuma and Somalia-Lwandle relative motions across Madagascar and evaluate whether they are consistent with GPS measurements made on the island itself, as well as with other kinematic indicators.

Path-Constrained Motion Planning for Robotics Based on Kinematic Constraints

NARCIS (Netherlands)

Dijk, van N.J.M.; Wouw, van de N.; Pancras, W.C.M.; Nijmeijer, H.

2007-01-01

Common robotic tracking tasks consist of motions along predefined paths. The design of time-optimal path-constrained trajectories for robotic applications is discussed in this paper. To increase industrial applicability, the proposed method accounts for robot kinematics together with actuator

Interactive inverse kinematics for human motion estimation

DEFF Research Database (Denmark)

Engell-Nørregård, Morten Pol; Hauberg, Søren; Lapuyade, Jerome

2009-01-01

We present an application of a fast interactive inverse kinematics method as a dimensionality reduction for monocular human motion estimation. The inverse kinematics solver deals efficiently and robustly with box constraints and does not suffer from shaking artifacts. The presented motion...... to significantly speed up the particle filtering. It should be stressed that the observation part of the system has not been our focus, and as such is described only from a sense of completeness. With our approach it is possible to construct a robust and computationally efficient system for human motion estimation....

Effects of Different Footwear Properties and Surface Instability on Neuromuscular Activity and Kinematics During Jumping.

Science.gov (United States)

Lesinski, Melanie; Prieske, Olaf; Borde, Ron; Beurskens, Rainer; Granacher, Urs

2018-04-13

Lesinski, M, Prieske, O, Borde, R, Beurskens, R, and Granacher, U. Effects of different footwear properties and surface instability on neuromuscular activity and kinematics during jumping. J Strength Cond Res XX(X): 000-000, 2018-The purpose of this study was to examine sex-specific effects of different footwear properties vs. barefoot condition during the performance of drop jumps (DJs) on stable and unstable surfaces on measures of jump performance, electromyographic (EMG) activity, and knee joint kinematics. Drop jump performance, EMG activity of lower-extremity muscles, as well as sagittal and frontal knee joint kinematics were tested in 28 healthy male (n = 14) and female (n = 14) physically active sports science students (23 ± 2 years) during the performance of DJs on stable and unstable surfaces using different footwear properties (elastic vs. minimal shoes) vs. barefoot condition. Analysis revealed a significantly lower jump height and performance index (Δ7-12%; p footwear conditions (Δ29%; p footwear-surface interactions were detected. Our findings revealed that surface instability had an impact on DJ performance, thigh/shank muscle activity, and knee joint kinematics. In addition, the single factors "footwear" and "sex" modulated knee joint kinematics during DJs. However, hardly any significant interaction effects were found. Thus, additional footwear-related effects can be neglected when performing DJs during training on different surfaces.

Kinematic Constraints Associated with the Acquisition of Overarm Throwing Part II: Upper Extremity Actions

Science.gov (United States)

Stodden, David F.; Langendorfer, Stephen J.; Fleisig, Glenn S.; Andrews, James R.

2006-01-01

The purposes of this study were to: (a) examine the differences within 11 specific kinematic variables and an outcome measure (ball velocity) associated with component developmental levels of humerus and forearm action (Roberton & Halverson, 1984), and (b) if the differences in kinematic variables were significantly associated with the differences…

Kinematic and Electromyographic Activity Changes during Back Squat with Submaximal and Maximal Loading

Science.gov (United States)

Erdag, Deniz

2017-01-01

The aim of this study was to investigate the possible kinematic and muscular activity changes with maximal loading during squat maneuver. Fourteen healthy male individuals, who were experienced at performing squats, participated in this study. Each subject performed squats with 80%, 90%, and 100% of the previously established 1 repetition maximum (1RM). Electromyographic (EMG) activities were measured for the vastus lateralis, vastus medialis, rectus femoris, semitendinosus, biceps femoris, gluteus maximus, and erector spinae by using an 8-channel dual-mode portable EMG and physiological signal data acquisition system (Myomonitor IV, Delsys Inc., Boston, MA, USA). Kinematical data were analyzed by using saSuite 2D kinematical analysis program. Data were analyzed with repeated measures analysis of variance (p squat may not be necessary for focusing on knee extensor improvement and may increase the lumbar injury risk. PMID:28546738

Kinematic control of redundant robots and the motion optimizability measure.

Science.gov (United States)

Li, L; Gruver, W A; Zhang, Q; Yang, Z

2001-01-01

This paper treats the kinematic control of manipulators with redundant degrees of freedom. We derive an analytical solution for the inverse kinematics that provides a means for accommodating joint velocity constraints in real time. We define the motion optimizability measure and use it to develop an efficient method for the optimization of joint trajectories subject to multiple criteria. An implementation of the method for a 7-dof experimental redundant robot is present.

Decoupled Closed-Form Solution for Humanoid Lower Limb Kinematics

Directory of Open Access Journals (Sweden)

Alejandro Said

2015-01-01

Full Text Available This paper presents an explicit, omnidirectional, analytical, and decoupled closed-form solution for the lower limb kinematics of the humanoid robot NAO. The paper starts by decoupling the position and orientation analysis from the overall Denavit-Hartenberg (DH transformation matrices. Here, the joint activation sequence for the DH matrices is based on the geometry of a triangle. Furthermore, the implementation of a forward and a reversed kinematic analysis for the support and swing phase equations is developed to avoid matrix inversion. The allocation of constant transformations allows the position and orientation end-coordinate systems to be aligned with each other. Also, the redefinition of the DH transformations and the use of constraints allow decoupling the shared DOF between the legs and the torso. Finally, a geometric approach to avoid the singularities during the walking process is indicated. Numerical data is presented along with an experimental implementation to prove the validity of the analytical results.

Knee Kinematics Estimation Using Multi-Body Optimisation Embedding a Knee Joint Stiffness Matrix: A Feasibility Study.

Science.gov (United States)

Richard, Vincent; Lamberto, Giuliano; Lu, Tung-Wu; Cappozzo, Aurelio; Dumas, Raphaël

2016-01-01

The use of multi-body optimisation (MBO) to estimate joint kinematics from stereophotogrammetric data while compensating for soft tissue artefact is still open to debate. Presently used joint models embedded in MBO, such as mechanical linkages, constitute a considerable simplification of joint function, preventing a detailed understanding of it. The present study proposes a knee joint model where femur and tibia are represented as rigid bodies connected through an elastic element the behaviour of which is described by a single stiffness matrix. The deformation energy, computed from the stiffness matrix and joint angles and displacements, is minimised within the MBO. Implemented as a "soft" constraint using a penalty-based method, this elastic joint description challenges the strictness of "hard" constraints. In this study, estimates of knee kinematics obtained using MBO embedding four different knee joint models (i.e., no constraints, spherical joint, parallel mechanism, and elastic joint) were compared against reference kinematics measured using bi-planar fluoroscopy on two healthy subjects ascending stairs. Bland-Altman analysis and sensitivity analysis investigating the influence of variations in the stiffness matrix terms on the estimated kinematics substantiate the conclusions. The difference between the reference knee joint angles and displacements and the corresponding estimates obtained using MBO embedding the stiffness matrix showed an average bias and standard deviation for kinematics of 0.9±3.2° and 1.6±2.3 mm. These values were lower than when no joint constraints (1.1±3.8°, 2.4±4.1 mm) or a parallel mechanism (7.7±3.6°, 1.6±1.7 mm) were used and were comparable to the values obtained with a spherical joint (1.0±3.2°, 1.3±1.9 mm). The study demonstrated the feasibility of substituting an elastic joint for more classic joint constraints in MBO.

Sequencing bilateral robot-assisted arm therapy and constraint-induced therapy improves reach to press and trunk kinematics in patients with stroke.

Science.gov (United States)

Hsieh, Yu-wei; Liing, Rong-jiuan; Lin, Keh-chung; Wu, Ching-yi; Liou, Tsan-hon; Lin, Jui-chi; Hung, Jen-wen

2016-03-22

The combination of robot-assisted therapy (RT) and a modified form of constraint-induced therapy (mCIT) shows promise for improving motor function of patients with stroke. However, whether the changes of motor control strategies are concomitant with the improvements in motor function after combination of RT and mCIT (RT + mCIT) is unclear. This study investigated the effects of the sequential combination of RT + mCIT compared with RT alone on the strategies of motor control measured by kinematic analysis and on motor function and daily performance measured by clinical scales. The study enrolled 34 patients with chronic stroke. The data were derived from part of a single-blinded randomized controlled trial. Participants in the RT + mCIT and RT groups received 20 therapy sessions (90 to 105 min/day, 5 days for 4 weeks). Patients in the RT + mCIT group received 10 RT sessions for first 2 weeks and 10 mCIT sessions for the next 2 weeks. The Bi-Manu-Track was used in RT sessions to provide bilateral practice of wrist and forearm movements. The primary outcome was kinematic variables in a task of reaching to press a desk bell. Secondary outcomes included scores on the Wolf Motor Function Test, Functional Independence Measure, and Nottingham Extended Activities of Daily Living. All outcome measures were administered before and after intervention. RT + mCIT and RT demonstrated different benefits on motor control strategies. RT + mCIT uniquely improved motor control strategies by reducing shoulder abduction, increasing elbow extension, and decreasing trunk compensatory movement during the reaching task. Motor function and quality of the affected limb was improved, and patients achieved greater independence in instrumental activities of daily living. Force generation at movement initiation was improved in the patients who received RT. A combination of RT and mCIT could be an effective approach to improve stroke rehabilitation outcomes, achieving

About the kinematics of spinning particles

International Nuclear Information System (INIS)

Salesi, G.; Recami, E.; Istituto Nazionale di Fisica Nucleare, Milan; Campinas State Univ., SP

1995-06-01

Inserting the correct Lorentz factor into the definition of the 4-velocity vμ for spinning particles entails new kinematical properties for v 2 . The well-know constraint (identically true for scalar particles, but entering also the Dirac theory, and assumed a priori in all spinning particle models) P μ v μ =m is here derived in a self-consistent way

The perceived constraints, motivation, and physical activity levels of ...

African Journals Online (AJOL)

The purpose of this research was threefold; Are Korean youth physically active to promote health during leisure time? What constraints to physical active do youth experience during leisure time? Are there relationships among constraints, motivation, and physical activity level? Of 1 280 youth randomly selected by a ...

Disassociation between primary motor cortical activity and movement kinematics during adaptation to reach perturbations.

Science.gov (United States)

Cai, X; Shimansky, Y P; Weber, D J; He, Jiping

2004-01-01

The relationship between movement kinematics and motor cortical activity was studied in monkeys performing a center-out reaching task during their adaptation to force perturbations applied to the wrist. The main feature of adaptive changes in movement kinematics was anticipatory deviation of hand paths in the direction opposite to that of the upcoming perturbation. We identified a group of neurons in the dorsal lateral portion of the primary motor cortex where a gradual buildup of spike activity immediately preceding the actual (in perturbation trials) or the "would-be" (in unperturbed/catch trials) perturbation onset was observed. These neurons were actively involved in the adaptation process, which was evident from the gradual increase in the amplitude of their movement-related modulation of spike activity from virtual zero and development of certain directional tuning pattern (DTP). However, the day-to-day dynamics of the kinematics adaptation was dramatically different from that of the neuronal activity. Hence, the adaptive modification of the motor cortical activity is more likely to reflect the development of the internal model of the perturbation dynamics, rather than motor instructions determining the adaptive behavior.

Relationship between participation in leisure activities and constraints on Taiwanese breastfeeding mothers during leisure activities.

Science.gov (United States)

Chow, Hsueh-wen; Dong, Yin-Han

2013-04-30

Participation in leisure activities strongly associates with health and well-being. Little research has explored the relationship between participation in leisure activities and constraints on breastfeeding mothers during leisure activities. The purposes of this study are: 1) to investigate constraints on breastfeeding mothers during leisure activities and participation in leisure activities; 2) to investigate the differences between preferences for leisure activities and actual participation by breastfeeding mothers; 3) to segment breastfeeding mothers with similar patterns, using a cluster analysis based on the delineated participation in leisure activities and leisure preferences; 4) to explore any differences between clusters of breastfeeding mothers with respect to socio-demographic characteristics, breastfeeding behaviours and leisure constraints. This study has a cross-sectional design using an online survey conducted among mothers having breastfeeding experiences of more than four months. The questionnaire includes demographic variables, breastfeeding behaviours, preferences for leisure activities participation, and constraints on leisure activities. Collection of data occurred between March and July 2011, producing 415 valid responses for analysis. For breastfeeding mothers, this study identifies constraints on breastfeeding related to leisure activities in addition to the three traditional factors for constraints in the model. This study demonstrates that reports of constraints related to children, family, and nursing environments are the most frequent. Breastfeeding mothers in Taiwan participate regularly in family activities or activities related to their children. Cluster analysis classified breastfeeding mothers into Action and Contemplation groups, and found that mothers within the latter group participate less in leisure activities and experienced more constraints related to breastfeeding. Implications provide a developmental design for public

Internal Stellar Kinematics of M32 from the SPLASH Survey: Dark Halo Constraints

Science.gov (United States)

Howley, K. M.; Guhathakurta, P.; van der Marel, R.; Geha, M.; Kalirai, J.; Yniguez, B.; Kirby, E.; Cuillandre, J.-C.; Gilbert, K.

2013-03-01

As part of the SPLASH survey of the Andromeda (M31) system, we have obtained Keck/DEIMOS spectra of the compact elliptical (cE) satellite M32. This is the first resolved-star kinematical study of any cE galaxy. In contrast to most previous kinematical studies that extended out to r information to account statistically for M31 contamination. The rotation curve and velocity dispersion profile extend well beyond the radius (r ~ 150'') where the isophotes are distorted. Unlike NGC 205, another close dwarf companion of M31, M32's kinematics appear regular and symmetric and do not show obvious sharp gradients across the region of isophotal elongation and twists. We interpret M31's kinematics using three-integral axisymmetric dynamical equilibrium models constructed using Schwarzschild's orbit superposition technique. Models with a constant mass-to-light ratio can fit the data remarkably well. However, since such a model requires an increasing tangential anisotropy with radius, invoking the presence of an extended dark halo may be more plausible. Such an extended dark halo is definitely required to bind a half-dozen fast-moving stars observed at the largest radii, but these stars may not be an equilibrium component of M32. Data herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

The Glasgow-Maastricht foot model, evaluation of a 26 segment kinematic model of the foot

OpenAIRE

Oosterwaal, Michiel; Carbes, Sylvain; Telfer, Scott; Woodburn, James; T?rholm, S?ren; Al-Munajjed, Amir A.; van Rhijn, Lodewijk; Meijer, Kenneth

2016-01-01

Background Accurately measuring of intrinsic foot kinematics using skin mounted markers is difficult, limited in part by the physical dimensions of the foot. Existing kinematic foot models solve this problem by combining multiple bones into idealized rigid segments. This study presents a novel foot model that allows the motion of the 26 bones to be individually estimated via a combination of partial joint constraints and coupling the motion of separate joints using kinematic rhythms. Methods ...

Impact of uncertain reference-frame motions in plate kinematic reconstructions

DEFF Research Database (Denmark)

Iaffaldano, Giampiero; Stein, Seth

2017-01-01

Geoscientists infer past plate motions, which serve as fundamental constraints for a range of studies, from observations of magnetic isochrons as well as hotspots tracks on the ocean floor and, for stages older than the Cretaceous, from paleomagnetic data. These observations effectively represent...... time-integrals of past plate motions but, because they are made at present, yield plate kinematics naturally tied to a present-day reference-frame, which may be another plate or a hotspots system. These kinematics are therefore different than those occurred at the time when the rocks acquired...... – in a temporal sense – and prone to noise. This limitation is commonly perceived to hamper the correction of plate kinematic reconstructions for RFAMs, but the extent to which this may be the case has not been explored. Here we assess the impact of uncertain RFAMs on kinematic reconstructions using synthetic...

Kinematic Constraints Associated with the Acquisition of Overarm Throwing Part I: Step and Trunk Actions

Science.gov (United States)

Stodden, David F.; Langendorfer, Stephen J.; Fleisig, Glenn S.; Andrews, James R.

2006-01-01

The purposes of this study were to: (a) examine differences within specific kinematic variables and ball velocity associated with developmental component levels of step and trunk action (Roberton & Halverson, 1984), and (b) if the differences in kinematic variables were significantly associated with the differences in component levels, determine…

Evaluating the Relationship Between Muscle Activation and Spine Kinematics Through Wavelet Coherence.

Science.gov (United States)

Hay, Dean C; Wachowiak, Mark P; Graham, Ryan B

2016-10-01

Advances in time-frequency analysis can provide new insights into the important, yet complex relationship between muscle activation (ie, electromyography [EMG]) and motion during dynamic tasks. We use wavelet coherence to compare a fundamental cyclical movement (lumbar spine flexion and extension) to the surface EMG linear envelope of 2 trunk muscles (lumbar erector spinae and internal oblique). Both muscles cohere to the spine kinematics at the main cyclic frequency, but lumbar erector spinae exhibits significantly greater coherence than internal oblique to kinematics at 0.25, 0.5, and 1.0 Hz. Coherence phase plots of the 2 muscles exhibit different characteristics. The lumbar erector spinae precedes trunk extension at 0.25 Hz, whereas internal oblique is in phase with spine kinematics. These differences may be due to their proposed contrasting functions as a primary spine mover (lumbar erector spinae) versus a spine stabilizer (internal oblique). We believe that this method will be useful in evaluating how a variety of factors (eg, pain, dysfunction, pathology, fatigue) affect the relationship between muscles' motor inputs (ie, activation measured using EMG) and outputs (ie, the resulting joint motion patterns).

Knee Kinematics Estimation Using Multi-Body Optimisation Embedding a Knee Joint Stiffness Matrix: A Feasibility Study.

Directory of Open Access Journals (Sweden)

Vincent Richard

Full Text Available The use of multi-body optimisation (MBO to estimate joint kinematics from stereophotogrammetric data while compensating for soft tissue artefact is still open to debate. Presently used joint models embedded in MBO, such as mechanical linkages, constitute a considerable simplification of joint function, preventing a detailed understanding of it. The present study proposes a knee joint model where femur and tibia are represented as rigid bodies connected through an elastic element the behaviour of which is described by a single stiffness matrix. The deformation energy, computed from the stiffness matrix and joint angles and displacements, is minimised within the MBO. Implemented as a "soft" constraint using a penalty-based method, this elastic joint description challenges the strictness of "hard" constraints. In this study, estimates of knee kinematics obtained using MBO embedding four different knee joint models (i.e., no constraints, spherical joint, parallel mechanism, and elastic joint were compared against reference kinematics measured using bi-planar fluoroscopy on two healthy subjects ascending stairs. Bland-Altman analysis and sensitivity analysis investigating the influence of variations in the stiffness matrix terms on the estimated kinematics substantiate the conclusions. The difference between the reference knee joint angles and displacements and the corresponding estimates obtained using MBO embedding the stiffness matrix showed an average bias and standard deviation for kinematics of 0.9±3.2° and 1.6±2.3 mm. These values were lower than when no joint constraints (1.1±3.8°, 2.4±4.1 mm or a parallel mechanism (7.7±3.6°, 1.6±1.7 mm were used and were comparable to the values obtained with a spherical joint (1.0±3.2°, 1.3±1.9 mm. The study demonstrated the feasibility of substituting an elastic joint for more classic joint constraints in MBO.

STUDY OF THE flat die pellet mills kinematic diagram with active cylindrical press rolLS

Directory of Open Access Journals (Sweden)

Osokin Anton Vladislavovich

2017-03-01

Full Text Available Though being widely spread, the designs of such machines as flat die pellet mills have hardly been comprehensively theoretically studied. At the same time, the kinematic motion of the ring die pellet mill executive parts have been studied quite thoroughly. The machine executive parts kinematics determines the nature of their motion and velocity parameters, as well as the energy costs for the unit operation of the assembly. In addition, a detailed analysis of the facility kinematic diagram enables a rational approach to the design process for a new equipment. In view of this, this paper proposes a classification of flat matrix granulators over the kinematic diagrams of the executive parts interactions. We performed an analytical study of the kinematic diagram flat matrix granulator with active cylindrical press rolls. We considered the forces acting on the press roll during its operation. We determined the kinematic parameters and their interrelation with the design parameters of the press roll. We obtained the analytical equations for the of the neutral cross-section determination - the most characteristic section of the press-roll granulator

Null Space Integration Method for Constrained Multibody Systems with No Constraint Violation

International Nuclear Information System (INIS)

Terze, Zdravko; Lefeber, Dirk; Muftic, Osman

2001-01-01

A method for integrating equations of motion of constrained multibody systems with no constraint violation is presented. A mathematical model, shaped as a differential-algebraic system of index 1, is transformed into a system of ordinary differential equations using the null-space projection method. Equations of motion are set in a non-minimal form. During integration, violations of constraints are corrected by solving constraint equations at the position and velocity level, utilizing the metric of the system's configuration space, and projective criterion to the coordinate partitioning method. The method is applied to dynamic simulation of 3D constrained biomechanical system. The simulation results are evaluated by comparing them to the values of characteristic parameters obtained by kinematics analysis of analyzed motion based unmeasured kinematics data

Uplift rates of marine terraces as a constraint on fault-propagation fold kinematics: Examples from the Hawkswood and Kate anticlines, North Canterbury, New Zealand

Science.gov (United States)

Oakley, David O. S.; Fisher, Donald M.; Gardner, Thomas W.; Stewart, Mary Kate

2018-01-01

Marine terraces on growing fault-propagation folds provide valuable insight into the relationship between fold kinematics and uplift rates, providing a means to distinguish among otherwise non-unique kinematic model solutions. Here, we investigate this relationship at two locations in North Canterbury, New Zealand: the Kate anticline and Haumuri Bluff, at the northern end of the Hawkswood anticline. At both locations, we calculate uplift rates of previously dated marine terraces, using DGPS surveys to estimate terrace inner edge elevations. We then use Markov chain Monte Carlo methods to fit fault-propagation fold kinematic models to structural geologic data, and we incorporate marine terrace uplift into the models as an additional constraint. At Haumuri Bluff, we find that marine terraces, when restored to originally horizontal surfaces, can help to eliminate certain trishear models that would fit the geologic data alone. At Kate anticline, we compare uplift rates at different structural positions and find that the spatial pattern of uplift rates is more consistent with trishear than with a parallel-fault propagation fold kink-band model. Finally, we use our model results to compute new estimates for fault slip rates ( 1-2 m/ka at Kate anticline and 1-4 m/ka at Haumuri Bluff) and ages of the folds ( 1 Ma), which are consistent with previous estimates for the onset of folding in this region. These results are consistent with previous work on the age of onset of folding in this region, provide revised estimates of fault slip rates necessary to understand the seismic hazard posed by these faults, and demonstrate the value of incorporating marine terraces in inverse fold kinematic models as a means to distinguish among non-unique solutions.

The graviton vacuum as a distributional state in kinematic loop quantum gravity

International Nuclear Information System (INIS)

Varadarajan, Madhavan

2005-01-01

The quantum behaviour of weak gravitational fields admits an adequate, albeit approximate, description by those graviton states in which the expectation values and fluctuations of the linearized gravitational field are small. Such states must approximate corresponding states in full quantum gravity. We analyse the nature of this approximation for the graviton vacuum state in the context of kinematical loop quantum gravity (LQG) wherein the constraints are ignored. We identify the graviton vacuum state with kinematically non-normalizable, distributional states in LQG by demanding that relations between linearized operator actions on the former are mirrored by those of their nonlinear counterparts on the latter. We define a semi-norm on the space of kinematical distributions and show that the identification is approximate up to distributions which are small in this semi-norm. We argue that our candidate states are annihilated by the linearized constraints (expressed as operators in the full theory) to leading order in the parameter characterizing the approximation. This suggests the possibility, in a scheme such as ours, of solving the full constraints order by order in this parameter. The main drawback of our considerations is that they depend on certain auxilliary constructions which, though mathematically well defined, do not arise from physical insight. Our work is an attempt to implement an earlier proposal of Iwasaki and Rovelli

Caliko: An Inverse Kinematics Software Library Implementation of the FABRIK Algorithm

OpenAIRE

Lansley, Alastair; Vamplew, Peter; Smith, Philip; Foale, Cameron

2016-01-01

The Caliko library is an implementation of the FABRIK (Forward And Backward Reaching Inverse Kinematics) algorithm written in Java. The inverse kinematics (IK) algorithm is implemented in both 2D and 3D, and incorporates a variety of joint constraints as well as the ability to connect multiple IK chains together in a hierarchy. The library allows for the simple creation and solving of multiple IK chains as well as visualisation of these solutions. It is licensed under the MIT software license...

Kinematic and Electromyographic Activity Changes during Back Squat with Submaximal and Maximal Loading

Directory of Open Access Journals (Sweden)

Hasan U. Yavuz

2017-01-01

Full Text Available The aim of this study was to investigate the possible kinematic and muscular activity changes with maximal loading during squat maneuver. Fourteen healthy male individuals, who were experienced at performing squats, participated in this study. Each subject performed squats with 80%, 90%, and 100% of the previously established 1 repetition maximum (1RM. Electromyographic (EMG activities were measured for the vastus lateralis, vastus medialis, rectus femoris, semitendinosus, biceps femoris, gluteus maximus, and erector spinae by using an 8-channel dual-mode portable EMG and physiological signal data acquisition system (Myomonitor IV, Delsys Inc., Boston, MA, USA. Kinematical data were analyzed by using saSuite 2D kinematical analysis program. Data were analyzed with repeated measures analysis of variance (p<0.05. Overall muscle activities increased with increasing loads, but significant increases were seen only for vastus medialis and gluteus maximus during 90% and 100% of 1RM compared to 80% while there was no significant difference between 90% and 100% for any muscle. The movement pattern in the hip joint changed with an increase in forward lean during maximal loading. Results may suggest that maximal loading during squat may not be necessary for focusing on knee extensor improvement and may increase the lumbar injury risk.

Rebound boots change lower limb muscle activation and kinematics during different fitness exercises.

Science.gov (United States)

Rossato, Mateus; Dellagrana, Rodolfo André; Dos Santos, Juliane Cristine Lopes; Carpes, Felipe P; Gheller, Rodrigo Ghedini; da Silva, De Angelys de Ceselles Seixas; Bezerra, Ewertton de Souza; Dos Santos, João Otacílio Libardoni

2017-10-01

The purpose of this study was to evaluate electromyography and kinematic parameters of the lower limbs using rebound boots (RB) and barefoot during a gym workout. This information can be helpful to practitioners to schedule rehabilitation and training programs. Ten women (25 ± 9 years) volunteered for the study; inclusion criteria were as follows: subjects must have experienced the use of RB and the analyzed exercises for at least 6 months, and have no previous injuries in the lower limbs. Seven exercises were performed for 30 s with the RB and subsequently barefoot. Data from muscle activation of vastus lateralis (VL), biceps femoris (BF), lateral gastrocnemius (LG) and 2D kinematics were collected. The use of RB triggered postural changes, characterized by greater hip extension (in 4 of the exercises) and knee extension (in 6 of the exercises) for the landing. RB reduced activation mainly in LG (in 6 of the exercise) while no changes were observed for VL (except in exercise 1) and BF. RB change kinematics and muscle activation suggesting changes in the way the legs absorb and transmit force during jumps. LG was the main muscle affected by the use of RB. Copyright © 2017 Elsevier Ltd. All rights reserved.

Constraint elimination in dynamical systems

Science.gov (United States)

Singh, R. P.; Likins, P. W.

1989-01-01

Large space structures (LSSs) and other dynamical systems of current interest are often extremely complex assemblies of rigid and flexible bodies subjected to kinematical constraints. A formulation is presented for the governing equations of constrained multibody systems via the application of singular value decomposition (SVD). The resulting equations of motion are shown to be of minimum dimension.

The Relationship between Leisure Constraints, Constraint Negotiation Strategies and Facilitators with Recreational Sport Activity Participation of College Students

Science.gov (United States)

Kocak, Funda

2017-01-01

The aim of this study is to determine the constraints in participating the leisure activities for college students, the strategies of negotiation regarding these constraints and the relationship between the facilitators and activity participation. The population of the study consists of currently registered students from Ankara University.…

Inverse kinematics for the variable geometry truss manipulator via a Lagrangian dual method

Directory of Open Access Journals (Sweden)

Yanchun Zhao

2016-11-01

Full Text Available This article studies the inverse kinematics problem of the variable geometry truss manipulator. The problem is cast as an optimization process which can be divided into two steps. Firstly, according to the information about the location of the end effector and fixed base, an optimal center curve and the corresponding distribution of the intermediate platforms along this center line are generated. This procedure is implemented by solving a non-convex optimization problem that has a quadratic objective function subject to quadratic constraints. Then, in accordance with the distribution of the intermediate platforms along the optimal center curve, all lengths of the actuators are calculated via the inverse kinematics of each variable geometry truss module. Hence, the approach that we present is an optimization procedure that attempts to generate the optimal intermediate platform distribution along the optimal central curve, while the performance index and kinematic constraints are satisfied. By using the Lagrangian duality theory, a closed-form optimal solution of the original optimization is given. The numerical simulation substantiates the effectiveness of the introduced approach.

The APOSTLE project: Local Group kinematic mass constraints and simulation candidate selection

Science.gov (United States)

Fattahi, Azadeh; Navarro, Julio F.; Sawala, Till; Frenk, Carlos S.; Oman, Kyle A.; Crain, Robert A.; Furlong, Michelle; Schaller, Matthieu; Schaye, Joop; Theuns, Tom; Jenkins, Adrian

2016-03-01

We use a large sample of isolated dark matter halo pairs drawn from cosmological N-body simulations to identify candidate systems whose kinematics match that of the Local Group (LG) of galaxies. We find, in agreement with the `timing argument' and earlier work, that the separation and approach velocity of the Milky Way (MW) and Andromeda (M31) galaxies favour a total mass for the pair of ˜5 × 1012 M⊙. A mass this large, however, is difficult to reconcile with the small relative tangential velocity of the pair, as well as with the small deceleration from the Hubble flow observed for the most distant LG members. Halo pairs that match these three criteria have average masses a factor of ˜2 times smaller than suggested by the timing argument, but with large dispersion. Guided by these results, we have selected 12 halo pairs with total mass in the range 1.6-3.6 × 1012 M⊙ for the APOSTLE project (A Project Of Simulating The Local Environment), a suite of hydrodynamical resimulations at various numerical resolution levels (reaching up to ˜104 M⊙ per gas particle) that use the subgrid physics developed for the EAGLE project. These simulations reproduce, by construction, the main kinematics of the MW-M31 pair, and produce satellite populations whose overall number, luminosities, and kinematics are in good agreement with observations of the MW and M31 companions. The APOSTLE candidate systems thus provide an excellent testbed to confront directly many of the predictions of the Λ cold dark matter cosmology with observations of our local Universe.

Automated Kinematics Equations Generation and Constrained Motion Planning Resolution for Modular and Reconfigurable Robots

Energy Technology Data Exchange (ETDEWEB)

Pin, Francois G.; Love, Lonnie L.; Jung, David L.

2004-03-29

Contrary to the repetitive tasks performed by industrial robots, the tasks in most DOE missions such as environmental restoration or Decontamination and Decommissioning (D&D) can be characterized as ''batches-of-one'', in which robots must be capable of adapting to changes in constraints, tools, environment, criteria and configuration. No commercially available robot control code is suitable for use with such widely varying conditions. In this talk we present our development of a ''generic code'' to allow real time (at loop rate) robot behavior adaptation to changes in task objectives, tools, number and type of constraints, modes of controls or kinematics configuration. We present the analytical framework underlying our approach and detail the design of its two major modules for the automatic generation of the kinematics equations when the robot configuration or tools change and for the motion planning under time-varying constraints. Sample problems illustrating the capabilities of the developed system are presented.

Kinematic Model of NAO Humanoid Robot

Directory of Open Access Journals (Sweden)

Miloš D. Jovanović

2014-06-01

Full Text Available This paper presents synthesis of kinematic model of NAO humanoid robot of Aldebaran Robotics. NAO humanoid robot has complex kinematic structure with 25 active degrees of freedom (DOF. Humanoid system is formed through 5 mutually depended kinematic chains. After that we applied standard aspects of kinematic chains synthesis and Denavit-Hartenberg parameters of each of 5 chains of robotic structure were introduced. Also, mutual relationships between chains were described, as well as their physical and structural dependence. Generated kinematic model will be the starting point for further dynamical modeling of NAO humanoid robot and motion synthesis on actual platform.

Transverse masses and kinematic constraints: from the boundary to the crease

International Nuclear Information System (INIS)

Barr, Alan J.; Gripaios, Ben; Lester, Christopher G.

2009-01-01

We re-examine the kinematic variable m T2 and its relatives in the light of recent work by Cheng and Han. Their proof that m T2 admits an equivalent, but implicit, definition as the 'boundary of the region of parent and daughter masses that is kinematically consistent with the event hypothesis' is far-reaching in its consequences. We generalize their result both to simpler cases (m T , the transverse mass) and to more complex cases (m TGen ). We further note that it is possible to re-cast many existing and unpleasant proofs (e.g. those relating to the existence or properties of 'kink' and 'crease' structures in m T2 ) into almost trivial forms by using the alternative definition. Not only does this allow us to gain better understanding of those existing results, but it also allows us to write down new (and more or less explicit) definitions of (a) the variable that naturally generalizes m T2 to the case in which the parent or daughter particles are not identical, and (b) the inverses of m T and m T2 - which may be useful if daughter masses are known and bounds on parent masses are required. We note the implications that these results may have for future matrix-element likelihood techniques.

Kinematic model of some types of motion of matter in active regions

International Nuclear Information System (INIS)

Platov, Yu.V.

1983-01-01

The kinematics of matter motion in variable magnetic fields of active regions on the Sun in the MHD approximation of a strong field and cold plasma is investigated. It is shown that the variation of sunspot magnetic moments lead to the development of different active phenomena in the solar atmosphere. The development of such phenomena at first can occur at the phase of active region growth, when new sunspots together with developed sunspots emerge in an active region or relative motions take place in a sunspot group

Intra-arc Seismicity: Geometry and Kinematic Constraints of Active Faulting along Northern Liquiñe-Ofqui and Andean Transverse Fault Systems [38º and 40ºS, Southern Andes

Science.gov (United States)

Sielfeld, G.; Lange, D.; Cembrano, J. M.

2017-12-01

Intra-arc crustal seismicity documents the schizosphere tectonic state along active magmatic arcs. At oblique-convergent margins, a significant portion of bulk transpressional deformation is accommodated in intra-arc regions, as a consequence of stress and strain partitioning. Simultaneously, crustal fluid migration mechanisms may be controlled by the geometry and kinematics of crustal high strain domains. In such domains shallow earthquakes have been associated with either margin-parallel strike-slip faults or to volcano-tectonic activity. However, very little is known on the nature and kinematics of Southern Andes intra-arc crustal seismicity and its relation with crustal faults. Here we present results of a passive seismicity study based on 16 months of data collected from 33 seismometers deployed along the intra-arc region of Southern Andes between 38˚S and 40˚S. This region is characterized by a long-lived interplay among margin-parallel strike-slip faults (Liquiñe-Ofqui Fault System, LOFS), second order Andean-transverse-faults (ATF), volcanism and hydrothermal activity. Seismic signals recorded by our network document small magnitude (0.2P and 2,796 S phase arrival times have been located with NonLinLoc. First arrival polarities and amplitude ratios of well-constrained events, were used for focal mechanism inversion. Local seismicity occurs at shallow levels down to depth of ca. 16 km, associated either with stratovolcanoes or to master, N10˚E, and subsidiary, NE to ENE, striking branches of the LOFS. Strike-slip focal mechanisms are consistent with the long-term kinematics documented by field structural-geology studies. Unexpected, well-defined NW-SE elongated clusters are also reported. In particular, a 72-hour-long, N60˚W-oriented seismicity swarm took place at Caburgua Lake area, describing a ca. 36x12x1km3 faulting crustal volume. Results imply a unique snapshot on shallow crustal tectonics, contributing to the understanding of faulting processes

On the constraints violation in forward dynamics of multibody systems

Energy Technology Data Exchange (ETDEWEB)

Marques, Filipe [University of Minho, Department of Mechanical Engineering (Portugal); Souto, António P. [University of Minho, Department of Textile Engineering (Portugal); Flores, Paulo, E-mail: pflores@dem.uminho.pt [University of Minho, Department of Mechanical Engineering (Portugal)

2017-04-15

It is known that the dynamic equations of motion for constrained mechanical multibody systems are frequently formulated using the Newton–Euler’s approach, which is augmented with the acceleration constraint equations. This formulation results in the establishment of a mixed set of partial differential and algebraic equations, which are solved in order to predict the dynamic behavior of general multibody systems. The classical solution of the equations of motion is highly prone to constraints violation because the position and velocity constraint equations are not fulfilled. In this work, a general and comprehensive methodology to eliminate the constraints violation at the position and velocity levels is offered. The basic idea of the described approach is to add corrective terms to the position and velocity vectors with the intent to satisfy the corresponding kinematic constraint equations. These corrective terms are evaluated as a function of the Moore–Penrose generalized inverse of the Jacobian matrix and of the kinematic constraint equations. The described methodology is embedded in the standard method to solve the equations of motion based on the technique of Lagrange multipliers. Finally, the effectiveness of the described methodology is demonstrated through the dynamic modeling and simulation of different planar and spatial multibody systems. The outcomes in terms of constraints violation at the position and velocity levels, conservation of the total energy and computational efficiency are analyzed and compared with those obtained with the standard Lagrange multipliers method, the Baumgarte stabilization method, the augmented Lagrangian formulation, the index-1 augmented Lagrangian, and the coordinate partitioning method.

The kinematical Hilbert space of loop quantum gravity from BF theories

International Nuclear Information System (INIS)

Cianfrani, Francesco

2011-01-01

In this work, it is demonstrated how the kinematical Hilbert space of loop quantum gravity (LQG) can be inferred from the configuration space of BF theories via the imposition of the Hamiltonian constraints. In particular, it is outlined how the projection to the representations associated with Ashtekar-Barbero connections provides the correct procedure to implement second-class constraints and the corresponding nontrivial induced symplectic structure. Then, the reduction to SU(2) invariant intertwiners is analyzed and the properties of LQG states under Lorentz transformations are discussed.

Caliko: An Inverse Kinematics Software Library Implementation of the FABRIK Algorithm

Directory of Open Access Journals (Sweden)

Alastair Lansley

2016-09-01

Full Text Available The Caliko library is an implementation of the FABRIK (Forward And Backward Reaching Inverse Kinematics algorithm written in Java. The inverse kinematics (IK algorithm is implemented in both 2D and 3D, and incorporates a variety of joint constraints as well as the ability to connect multiple IK chains together in a hierarchy. The library allows for the simple creation and solving of multiple IK chains as well as visualisation of these solutions. It is licensed under the MIT software license and the source code is freely available for use and modification at: https://github.com/feduni/caliko

The effects of weighted skates on ice-skating kinematics, kinetics and muscular activity.

Science.gov (United States)

Mavor, Matthew P; Hay, Dean C; Graham, Ryan B

2018-07-01

Sport-specific resistance training, through limb loading, can be a complimentary training method to traditional resistance training by loading the working muscles during all phases of a specific movement. The purpose of this study was to examine the acute effects of skating with an additional load on the skate, using a skate weight prototype, on kinematics, kinetics, and muscle activation during the acceleration phase while skating on a synthetic ice surface. 10 male hockey skaters accelerated from rest (standing erect with knees slightly bent) under four non-randomized load conditions: baseline 1 (no weight), light (0.9 kg per skate), heavy (1.8 kg per skate), and baseline 2 (no weight). Skating with additional weight caused athletes to skate slower (p skates decreased skating velocity, but athletes maintained similar muscle activation profiles (magnitude and trends) with minor changes to their skating kinematics.

Shoulder External Rotation Fatigue and Scapular Muscle Activation and Kinematics in Overhead Athletes

Science.gov (United States)

Joshi, Mithun; Thigpen, Charles A.; Bunn, Kevin; Karas, Spero G.; Padua, Darin A.

2011-01-01

Context: Glenohumeral external rotation (GH ER) muscle fatigue might contribute to shoulder injuries in overhead athletes. Few researchers have examined the effect of such fatigue on scapular kinematics and muscle activation during a functional movement pattern. Objective: To examine the effects of GH ER muscle fatigue on upper trapezius, lower trapezius, serratus anterior, and infraspinatus muscle activation and to examine scapular kinematics during a diagonal movement task in overhead athletes. Setting: Human performance research laboratory. Design: Descriptive laboratory study. Patients or Other Participants: Our study included 25 overhead athletes (15 men, 10 women; age = 20 ± 2 years, height = 180 ± 11 cm, mass = 80 ± 11 kg) without a history of shoulder pain on the dominant side. Interventions: We tested the healthy, dominant shoulder through a diagonal movement task before and after a fatiguing exercise involving low-resistance, high-repetition, prone GH ER from 0° to 75° with the shoulder in 90° of abduction. Main Outcome Measure(s): Surface electromyography was used to measure muscle activity for the upper trapezius, lower trapezius, serratus anterior, and infraspinatus. An electromyographic motion analysis system was used to assess 3-dimensional scapular kinematics. Repeated-measures analyses of variance (phase × condition) were used to test for differences. Results: We found a decrease in ascending-phase and descending-phase lower trapezius activity (F1,25 = 5.098, P = .03) and an increase in descending-phase infraspinatus activity (F1,25 = 5.534, P = .03) after the fatigue protocol. We also found an increase in scapular upward rotation (F1,24 = 3.7, P = .04) postfatigue. Conclusions: The GH ER muscle fatigue protocol used in this study caused decreased lower trapezius and increased infraspinatus activation concurrent with increased scapular upward rotation range of motion during the functional task. This highlights the interdependence of scapular

Inverse Dynamic Analysis for Various Drivings in Kinematic Systems

Energy Technology Data Exchange (ETDEWEB)

Lee, Byung Hoon [Pusan Nat’l Univ., Busan (Korea, Republic of)

2017-09-15

Analysis of actuating forces and joint reaction forces are essential to determine the capacity of actuators, to control the mechanical system and to design its components. This paper presents an algorithm that calculates actuating forces(or torques), depending on the various types of driving constraints, in order to produce a given system motion in the joint coordinate space. The joint coordinates are used as the generalized coordinates of a kinematic system. System equations of motion and constraint acceleration equations are transformed from the Cartesian coordinate space to the joint coordinate space using the velocity transformation method. A numerical example is carried out to verify the algorithm proposed.

Self-consistent Bulge/Disk/Halo Galaxy Dynamical Modeling Using Integral Field Kinematics

Science.gov (United States)

Taranu, D. S.; Obreschkow, D.; Dubinski, J. J.; Fogarty, L. M. R.; van de Sande, J.; Catinella, B.; Cortese, L.; Moffett, A.; Robotham, A. S. G.; Allen, J. T.; Bland-Hawthorn, J.; Bryant, J. J.; Colless, M.; Croom, S. M.; D'Eugenio, F.; Davies, R. L.; Drinkwater, M. J.; Driver, S. P.; Goodwin, M.; Konstantopoulos, I. S.; Lawrence, J. S.; López-Sánchez, Á. R.; Lorente, N. P. F.; Medling, A. M.; Mould, J. R.; Owers, M. S.; Power, C.; Richards, S. N.; Tonini, C.

2017-11-01

We introduce a method for modeling disk galaxies designed to take full advantage of data from integral field spectroscopy (IFS). The method fits equilibrium models to simultaneously reproduce the surface brightness, rotation, and velocity dispersion profiles of a galaxy. The models are fully self-consistent 6D distribution functions for a galaxy with a Sérsic profile stellar bulge, exponential disk, and parametric dark-matter halo, generated by an updated version of GalactICS. By creating realistic flux-weighted maps of the kinematic moments (flux, mean velocity, and dispersion), we simultaneously fit photometric and spectroscopic data using both maximum-likelihood and Bayesian (MCMC) techniques. We apply the method to a GAMA spiral galaxy (G79635) with kinematics from the SAMI Galaxy Survey and deep g- and r-band photometry from the VST-KiDS survey, comparing parameter constraints with those from traditional 2D bulge-disk decomposition. Our method returns broadly consistent results for shared parameters while constraining the mass-to-light ratios of stellar components and reproducing the H I-inferred circular velocity well beyond the limits of the SAMI data. Although the method is tailored for fitting integral field kinematic data, it can use other dynamical constraints like central fiber dispersions and H I circular velocities, and is well-suited for modeling galaxies with a combination of deep imaging and H I and/or optical spectra (resolved or otherwise). Our implementation (MagRite) is computationally efficient and can generate well-resolved models and kinematic maps in under a minute on modern processors.

Kinematics Control and Analysis of Industrial Robot

Science.gov (United States)

Zhu, Tongbo; Cai, Fan; Li, Yongmei; Liu, Wei

2018-03-01

The robot’s development present situation, basic principle and control system are introduced briefly. Research is mainly focused on the study of the robot’s kinematics and motion control. The structural analysis of a planar articulated robot (SCARA) robot is presented,the coordinate system is established to obtain the position and orientation matrix of the end effector,a method of robot kinematics analysis based on homogeneous transformation method is proposed, and the kinematics solution of the robot is obtained.Establishment of industrial robot’s kinematics equation and formula for positive kinematics by example. Finally,the kinematic analysis of this robot was verified by examples.It provides a basis for structural design and motion control.It has active significance to promote the motion control of industrial robot.

Parallel kinematics type, kinematics, and optimal design

CERN Document Server

Liu, Xin-Jun

2014-01-01

Parallel Kinematics- Type, Kinematics, and Optimal Design presents the results of 15 year's research on parallel mechanisms and parallel kinematics machines. This book covers the systematic classification of parallel mechanisms (PMs) as well as providing a large number of mechanical architectures of PMs available for use in practical applications. It focuses on the kinematic design of parallel robots. One successful application of parallel mechanisms in the field of machine tools, which is also called parallel kinematics machines, has been the emerging trend in advanced machine tools. The book describes not only the main aspects and important topics in parallel kinematics, but also references novel concepts and approaches, i.e. type synthesis based on evolution, performance evaluation and optimization based on screw theory, singularity model taking into account motion and force transmissibility, and others.   This book is intended for researchers, scientists, engineers and postgraduates or above with interes...

Effects of experimental insoles on body posture, mandibular kinematics and masticatory muscles activity. A pilot study in healthy volunteers.

Science.gov (United States)

Marini, Ida; Alessandri Bonetti, Giulio; Bortolotti, Francesco; Bartolucci, Maria Lavinia; Gatto, Maria Rosaria; Michelotti, Ambra

2015-06-01

It has been hypothesized that different plantar sensory inputs could influence the whole body posture and dental occlusion but there is a lack of evidence on this possible association. To investigate the effects of experimental insoles redistributing plantar pressure on body posture, mandibular kinematics and electromyographic (EMG) activity of masticatory muscles on healthy subjects. A pilot study was conducted on 19 healthy volunteers that wore custom-made insoles normalizing the plantar pressure distribution for 2 weeks. Body posture parameters were measured by means of an optoelectronic stereophotogrammetric analysis; mandibular kinematics was analyzed by means of gothic arch tracings; superficial EMG activity of head and neck muscles was performed. Measurements were carried out 10 days before the insertion of the insoles, immediately before the insertion, the day after, 7 and 14 days after, in four different exteroceptive conditions. The outcomes of the present study show that insoles do not modify significantly over time the parameters of body posture, SEMG activity of head and neck muscles and mandibular kinematics. In this pilot study the experimental insoles did not significantly influence the body posture, the mandibular kinematics and the activity of masticatory muscles during a 14-day follow up period. Copyright © 2015 Elsevier Ltd. All rights reserved.

Development of Kinematic Graphs of Median Nerve during Active Finger Motion: Implications of Smartphone Use.

Directory of Open Access Journals (Sweden)

Hoi-Chi Woo

Full Text Available Certain hand activities cause deformation and displacement of the median nerve at the carpal tunnel due to the gliding motion of tendons surrounding it. As smartphone usage escalates, this raises the public's concern whether hand activities while using smartphones can lead to median nerve problems.The aims of this study were to 1 develop kinematic graphs and 2 investigate the associated deformation and rotational information of median nerve in the carpal tunnel during hand activities.Dominant wrists of 30 young adults were examined with ultrasonography by placing a transducer transversely on their wrist crease. Ultrasound video clips were recorded when the subject performing 1 thumb opposition with the wrist in neutral position, 2 thumb opposition with the wrist in ulnar deviation and 3 pinch grip with the wrist in neutral position. Six still images that were separated by 0.2-second intervals were then captured from the ultrasound video for the determination of 1 cross-sectional area (CSA, 2 flattening ratio (FR, 3 rotational displacement (RD and 4 translational displacement (TD of median nerve in the carpal tunnel, and these collected information of deformation, rotational and displacement of median nerve were compared between 1 two successive time points during a single hand activity and 2 different hand motions at the same time point. Finally, kinematic graphs were constructed to demonstrate the mobility of median nerve during different hand activities.Performing different hand activities during this study led to a gradual reduction in CSA of the median nerve, with thumb opposition together with the wrist in ulnar deviation causing the greatest extent of deformation of the median nerve. Thumb opposition with the wrist in ulnar deviation also led to the largest extent of TD when compared to the other two hand activities of this study. Kinematic graphs showed that the motion pathways of median nerve during different hand activities were complex

Altered Perceptual Sensitivity to Kinematic Invariants in Parkinson's Disease

OpenAIRE

Dayan, Eran; Inzelberg, Rivka; Flash, Tamar

2012-01-01

Ample evidence exists for coupling between action and perception in neurologically healthy individuals, yet the precise nature of the internal representations shared between these domains remains unclear. One experimentally derived view is that the invariant properties and constraints characterizing movement generation are also manifested during motion perception. One prominent motor invariant is the "two-third power law," describing the strong relation between the kinematics of motion and th...

Kinematics of the lateral ligamentous constraints of the elbow joint

DEFF Research Database (Denmark)

Olsen, Bo Sanderhoff; Søjbjerg, Jens Ole; Dalstra, Michel

1996-01-01

preventer of elbow joint laxity. The LCLC was observed to be a complex structure of ligamentous fibers rather than discreet bands. The LCLC forms a ligamentous constraint between the lateral humeral epicondyle and the ulna, stabilizing the elbow joint and forming a base for radial head stability...

Kinematics, structural mechanics, and design of origami structures with smooth folds

Science.gov (United States)

Peraza Hernandez, Edwin Alexander

Origami provides novel approaches to the fabrication, assembly, and functionality of engineering structures in various fields such as aerospace, robotics, etc. With the increase in complexity of the geometry and materials for origami structures that provide engineering utility, computational models and design methods for such structures have become essential. Currently available models and design methods for origami structures are generally limited to the idealization of the folds as creases of zeroth-order geometric continuity. Such an idealization is not proper for origami structures having non-negligible thickness or maximum curvature at the folds restricted by material limitations. Thus, for general structures, creased folds of merely zeroth-order geometric continuity are not appropriate representations of structural response and a new approach is needed. The first contribution of this dissertation is a model for the kinematics of origami structures having realistic folds of non-zero surface area and exhibiting higher-order geometric continuity, here termed smooth folds. The geometry of the smooth folds and the constraints on their associated kinematic variables are presented. A numerical implementation of the model allowing for kinematic simulation of structures having arbitrary fold patterns is also described. Examples illustrating the capability of the model to capture realistic structural folding response are provided. Subsequently, a method for solving the origami design problem of determining the geometry of a single planar sheet and its pattern of smooth folds that morphs into a given three-dimensional goal shape, discretized as a polygonal mesh, is presented. The design parameterization of the planar sheet and the constraints that allow for a valid pattern of smooth folds and approximation of the goal shape in a known folded configuration are presented. Various testing examples considering goal shapes of diverse geometries are provided. Afterwards, a

Pa2 kinematic bond in translational parallel manipulators

Directory of Open Access Journals (Sweden)

A. Hernández

2018-01-01

Full Text Available The Pa2 pair is composed of two intertwined articulated parallelograms connecting in parallel two links of a kinematic chain. This pair has two translational degrees of freedom leading to a translational plane variable with the position. Currently, the Pa2 pair appears in conceptual designs presented in recent papers. However, its practical application is very limited. One of the reasons for this can be the high number of redundant constraints it has. But, it has to be considered that most of them can be eliminated by replacing wisely the revolute joints by spherical joints. On the other side, the structure of the Pa2 pair contributes to increase the global stiffness of the kinematic chain in which it is mounted. Also, its implementation is a promising alternative to the problematic passive prismatic joints. In this paper, the Pa2 pairs are used in the design of a 3 − P Pa2 parallel manipulator. The potentiality of this design is evaluated and proven after doing the following analyses: direct and inverse kinematics, singularity study, and workspace computation and assessment.

Kinematic Optimization in Birds, Bats and Ornithopters

Science.gov (United States)

Reichert, Todd

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

Optimizing Computation of Repairs from Active Integrity Constraints

DEFF Research Database (Denmark)

Cruz-Filipe, Luís

2014-01-01

Active integrity constraints (AICs) are a form of integrity constraints for databases that not only identify inconsistencies, but also suggest how these can be overcome. The semantics for AICs defines different types of repairs, but deciding whether an inconsistent database can be repaired...... and finding possible repairs is a NP- or Σ2p-complete problem, depending on the type of repairs one has in mind. In this paper, we introduce two different relations on AICs: an equivalence relation of independence, allowing the search to be parallelized among the equivalence classes, and a precedence relation...

Intervertebral anticollision constraints improve out-of-plane translation accuracy of a single-plane fluoroscopy-to-CT registration method for measuring spinal motion

International Nuclear Information System (INIS)

Lin, Cheng-Chung; Tsai, Tsung-Yuan; Hsu, Shih-Jung; Lu, Tung-Wu; Shih, Ting-Fang; Wang, Ting-Ming

2013-01-01

Purpose: The study aimed to propose a new single-plane fluoroscopy-to-CT registration method integrated with intervertebral anticollision constraints for measuring three-dimensional (3D) intervertebral kinematics of the spine; and to evaluate the performance of the method without anticollision and with three variations of the anticollision constraints via an in vitro experiment. Methods: The proposed fluoroscopy-to-CT registration approach, called the weighted edge-matching with anticollision (WEMAC) method, was based on the integration of geometrical anticollision constraints for adjacent vertebrae and the weighted edge-matching score (WEMS) method that matched the digitally reconstructed radiographs of the CT models of the vertebrae and the measured single-plane fluoroscopy images. Three variations of the anticollision constraints, namely, T-DOF, R-DOF, and A-DOF methods, were proposed. An in vitro experiment using four porcine cervical spines in different postures was performed to evaluate the performance of the WEMS and the WEMAC methods. Results: The WEMS method gave high precision and small bias in all components for both vertebral pose and intervertebral pose measurements, except for relatively large errors for the out-of-plane translation component. The WEMAC method successfully reduced the out-of-plane translation errors for intervertebral kinematic measurements while keeping the measurement accuracies for the other five degrees of freedom (DOF) more or less unaltered. The means (standard deviations) of the out-of-plane translational errors were less than −0.5 (0.6) and −0.3 (0.8) mm for the T-DOF method and the R-DOF method, respectively. Conclusions: The proposed single-plane fluoroscopy-to-CT registration method reduced the out-of-plane translation errors for intervertebral kinematic measurements while keeping the measurement accuracies for the other five DOF more or less unaltered. With the submillimeter and subdegree accuracy, the WEMAC method was

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

Science.gov (United States)

Oliver, Gretchen D; Plummer, Hillary

2011-07-01

The aims of the present study were to examine quantitatively ground reaction forces, kinematics, and muscle activations during the windmill softball pitch, and to determine relationships between knee valgus and muscle activations, ball velocity and muscle activation as well as ball velocity and ground reaction forces. It was hypothesized that there would be an inverse relationship between degree of knee valgus and muscle activation, a direct relationship between ground reaction forces and ball velocity, and non-stride leg muscle activations and ball velocity. Ten female windmill softball pitchers (age 17.6 ± 3.47 years, stature 1.67 ± 0.07 m, weight 67.4 ± 12.2 kg) participated. Dependent variables were ball velocity, surface electromyographic (sEMG), kinematic, and kinetic data while the participant was the independent variable. Stride foot contact reported peak vertical forces of 179% body weight. There were positive relationships between ball velocity and ground reaction force (r = 0.758, n = 10, P = 0.029) as well as ball velocity and non-stride leg gluteus maximus (r = 0.851, n = 10, P = 0.007) and medius (r = 0.760, n = 10, P = 0.029) muscle activity, while there was no notable relationship between knee valgus and muscle activation. As the windmill softball pitcher increased ball velocity, her vertical ground reaction forces also increased. Proper conditioning of the lumbopelvic-hip complex, including the gluteals, is essential for injury prevention. From the data presented, it is evident that bilateral strength and conditioning of the gluteal muscle group is salient in the windmill softball pitch as an attempt to decrease incidence of injury.

Surgical robot setup simulation with consistent kinematics and haptics for abdominal surgery.

Science.gov (United States)

Hayashibe, Mitsuhiro; Suzuki, Naoki; Hattori, Asaki; Suzuki, Shigeyuki; Konishi, Kozo; Kakeji, Yoshihiro; Hashizume, Makoto

2005-01-01

Preoperative simulation and planning of surgical robot setup should accompany advanced robotic surgery if their advantages are to be further pursued. Feedback from the planning system will plays an essential role in computer-aided robotic surgery in addition to preoperative detailed geometric information from patient CT/MRI images. Surgical robot setup simulation systems for appropriate trocar site placement have been developed especially for abdominal surgery. The motion of the surgical robot can be simulated and rehearsed with kinematic constraints at the trocar site, and the inverse-kinematics of the robot. Results from simulation using clinical patient data verify the effectiveness of the proposed system.

Treatment of photon radiation in kinematics fits at future e+e- colliders

International Nuclear Information System (INIS)

Beckmann, M.; List, J.; List, B.

2010-05-01

Kinematic fitting, where constraints such as energy and momentum conservation are imposed on measured four-vectors of jets and leptons, is an important tool to improve the resolution in high-energy physics experiments. At future e + e - colliders, photon radiation parallel to the beam carrying away large amounts of energy and momentum will become a challenge for kinematic fitting. A photon with longitudinal momentum p z,γ (η) is introduced, which is parametrized such that η follows a normal distribution. In the fit, η is treated as having a measured value of zero, which corresponds to p z,γ , = 0. As a result, fits with constraints on energy and momentum conservation converge well even in the presence of a highly energetic photon, while the resolution of fits without such a photon is retained. A fully simulated and reconstructed e + e - →q anti qq anti q event sample at √(s)=500 GeV is used to investigate the performance of this method under realistic conditions, as expected at the International Linear Collider. (orig.)

Kinematic signature of a rotating bar near a resonance

Science.gov (United States)

Weinberg, Martin D.

1994-01-01

Recent work based on H I, star count and emission data suggests that the Milky Way has rotating bar-like features. In this paper, I show that such features cause distinctive stellar kinematic signatures near Outer Lindblad Resonance (OLR) and Inner Lindblad Resonance (ILR). The effect of these resonances may be observable far from the peak density of the pattern and relatively nearby the solar position. The details of the kinematic signatures depend on the evolutionary history of the 'bar' and therefore velocity data, both systematic and velocity dispersion, may be used to probe the evolutionary history as well as the present state of Galaxy. Kinematic models for a variety of sample scenarios are presented. Models with evolving pattern speeds show significantly stronger dispersion signatures than those with static pattern speeds, suggesting that useful observational constraints are possible. The models are applied to the proposed rotating spheroid and bar models; we find (1) none of these models chosen to represent the proposed large-scale rotating spheroid are consistent with the stellar kinematics and (2) a Galactic bar with semimajor axis of 3 kpc will cause a large increase in velocity dispersion in the vicinity of OLR (approximately 5 kpc) with little change in the net radial motion and such a signature is suggested by K-giant velocity data. Potential future observations and analyses are discussed.

A Kinematically Beamed, Low Energy Pulsed Neutron Source for Active Interrogation

International Nuclear Information System (INIS)

Dietrich, D.; Hagmann, C.; Kerr, P.; Nakae, L.; Rowland, M.; Snyderman, N.; Stoeffl, W.; Hamm, R.

2004-01-01

We are developing a new active interrogation system based on a kinematically focused low energy neutron beam. The key idea is that one of the defining characteristics of SNM (Special Nuclear Materials) is the ability for low energy or thermal neutrons to induce fission. Thus by using low energy neutrons for the interrogation source we can accomplish three goals, (1) Energy discrimination allows us to measure the prompt fast fission neutrons produced while the interrogation beam is on; (2) Neutrons with an energy of approximately 60 to 100 keV do not fission 238U and Thorium, but penetrate bulk material nearly as far as high energy neutrons do and (3) below about 100keV neutrons lose their energy by kinematical collisions rather than via the nuclear (n,2n) or (n,n') processes thus further simplifying the prompt neutron induced background. 60 keV neutrons create a low radiation dose and readily thermal capture in normal materials, thus providing a clean spectroscopic signature of the intervening materials. The kinematically beamed source also eliminates the need for heavy backward and sideway neutron shielding. We have designed and built a very compact pulsed neutron source, based on an RFQ proton accelerator and a lithium target. We are developing fast neutron detectors that are nearly insensitive to the ever-present thermal neutron and neutron capture induced gamma ray background. The detection of only a few high energy fission neutrons in time correlation with the linac pulse will be a clear indication of the presence of SNM

Rapid kinematic finite source inversion for Tsunamic Early Warning using high rate GNSS data

Science.gov (United States)

Chen, K.; Liu, Z.; Song, Y. T.

2017-12-01

Recently, Global Navigation Satellite System (GNSS) has been used for rapid earthquake source inversion towards tsunami early warning. In practice, two approaches, i.e., static finite source inversion based on permanent co-seismic offsets and kinematic finite source inversion using high-rate (>= 1 Hz) co-seismic displacement waveforms, are often employed to fulfill the task. The static inversion is relatively easy to be implemented and does not require additional constraints on rupture velocity, duration, and temporal variation. However, since most GNSS receivers are deployed onshore locating on one side of the subduction fault, there is very limited resolution on near-trench fault slip using GNSS in static finite source inversion. On the other hand, the high-rate GNSS displacement waveforms, which contain the timing information of earthquake rupture explicitly and static offsets implicitly, have the potential to improve near-trench resolution by reconciling with the depth-dependent megathrust rupture behaviors. In this contribution, we assess the performance of rapid kinematic finite source inversion using high-rate GNSS by three selected historical tsunamigenic cases: the 2010 Mentawai, 2011 Tohoku and 2015 Illapel events. With respect to the 2010 Mentawai case, it is a typical tsunami earthquake with most slip concentrating near the trench. The static inversion has little resolution there and incorrectly puts slip at greater depth (>10km). In contrast, the recorded GNSS displacement waveforms are deficit in high-frequency energy, the kinematic source inversion recovers a shallow slip patch (depth less than 6 km) and tsunami runups are predicted quite reasonably. For the other two events, slip from kinematic and static inversion show similar characteristics and comparable tsunami scenarios, which may be related to dense GNSS network and behavior of the rupture. Acknowledging the complexity of kinematic source inversion in real-time, we adopt the back

Neural representations of kinematic laws of motion: evidence for action-perception coupling.

Science.gov (United States)

Dayan, Eran; Casile, Antonino; Levit-Binnun, Nava; Giese, Martin A; Hendler, Talma; Flash, Tamar

2007-12-18

Behavioral and modeling studies have established that curved and drawing human hand movements obey the 2/3 power law, which dictates a strong coupling between movement curvature and velocity. Human motion perception seems to reflect this constraint. The functional MRI study reported here demonstrates that the brain's response to this law of motion is much stronger and more widespread than to other types of motion. Compliance with this law is reflected in the activation of a large network of brain areas subserving motor production, visual motion processing, and action observation functions. Hence, these results strongly support the notion of similar neural coding for motion perception and production. These findings suggest that cortical motion representations are optimally tuned to the kinematic and geometrical invariants characterizing biological actions.

A KINEMATIC STUDY OF FINSWIMMING AT SURFACE

Directory of Open Access Journals (Sweden)

Pier-Giorgio Zanone

2004-06-01

Full Text Available Finswimming is a sport of speed practiced on the surface or underwater, in which performance is based on whole-body oscillations. The present study investigated the undulatory motion performed by finswimmers at the surface. This study aiming to analyze the influence of the interaction of gender, practice level, and race distance on selected kinematic parameters. Six elite and six novices finswimmers equipped with joints markers (wrist, elbow, shoulder, hip, knee, and ankle were recorded in the sagittal plane. The position of these anatomical marks was digitized at 50 Hz. An automated motion analysis software yielded velocity, vertical amplitude, frequency, and angular position. Results showed that stroke frequency decreased whereas the mean amplitude of all joints increased with increasing race distance (p < 0.01. Mean joint amplitude for the upper limbs (wrist, elbow and shoulder was smaller for experts than for novices. Whereas that of the ankle was larger, so that the oscillation amplitude increased from shoulder to ankle. Elite male finswimmers were pitching more acutely than female. Moreover, elite male finswimmers showed a smaller knee bending than novices and than elite females (p < 0.01. This indicated that elite male finswimmers attempt to reduce drag forces thanks to a weak knee bending and a low upper limbs pitch. To sum up, gender, expertise, and race distance affect the performance and its kinematics in terms frontal drag. Expertise in finswimming requires taking advantage of the mechanical constraints pertaining to hydrodynamic constraints in order to optimize performance

Relationship between gluteal muscle activation and upper extremity kinematics and kinetics in softball position players.

Science.gov (United States)

Oliver, Gretchen D

2014-03-01

As the biomechanical literature concerning softball pitching is evolving, there are no data to support the mechanics of softball position players. Pitching literature supports the whole kinetic chain approach including the lower extremity in proper throwing mechanics. The purpose of this project was to examine the gluteal muscle group activation patterns and their relationship with shoulder and elbow kinematics and kinetics during the overhead throwing motion of softball position players. Eighteen Division I National Collegiate Athletic Association softball players (19.2 ± 1.0 years; 68.9 ± 8.7 kg; 168.6 ± 6.6 cm) who were listed on the active playing roster volunteered. Electromyographic, kinematic, and kinetic data were collected while players caught a simulated hit or pitched ball and perform their position throw. Pearson correlation revealed a significant negative correlation between non-throwing gluteus maximus during the phase of maximum external rotation to maximum internal rotation (MIR) and elbow moments at ball release (r = -0.52). While at ball release, trunk flexion and rotation both had a positive relationship with shoulder moments at MIR (r = 0.69, r = 0.82, respectively) suggesting that the kinematic actions of the pelvis and trunk are strongly related to the actions of the shoulder during throwing.

Longitudinal evaluation of jaw muscle activity and mandibular kinematics in young patients with Class II malocclusion treated with the Teuscher activator.

Science.gov (United States)

Cuevas, Maria-José; Cacho, Alberto; Alarcón, Jose-Antonio; Martín, Conchita

2013-05-01

A longitudinal study was performed to evaluate the jaw muscle activity and mandibular kinematics after Teuscher activator treatment and at 2 years after orthodontic treatment completion. Twenty-seven children with Class II division 1 malocclusion were evaluated before treatment (T0; mean: 11.6 years), after functional treatment (T1; mean: 12.8 years), and 2 years after orthodontic treatment (T2; mean: 18 years). Bilateral surface electromyographic activities of the anterior temporalis, posterior temporalis, masseter, and suprahyoid muscle areas were analyzed at rest and during clenching, swallowing, and mastication. Kinematic recordings of the mandibular maximum opening, lateral shift, right and left lateral excursions, and protrusion were evaluated. Compared to T0, the left masseter activity during clenching was decreased at T1 but increased at T2, similar to the other evaluated muscles. The suprahyoid activity during swallowing was increased at T1 but decreased at T2. The masseter activity during mastication was increased at T1 and further increased at T2. The left and right lateral excursions and protrusion did not show significant changes throughout the experiment. Teuscher activator and subsequent fixed orthodontic treatment improved jaw muscle function; however, a long period was needed to attain complete neuromuscular adaptation.

PDF constraints from top-quark pair differential measurements

CERN Document Server

García Navarro, José Enrique; The ATLAS collaboration

2018-01-01

Constraints on parton distribution functions are presented that are based on differential cross-section measurements of single lepton and dilepton kinematic distributions in dileptonic top quark pair events. The measurements utilize 20.2 fb-1 of sqrt(s) = 8 TeV pp collisions recorded by the ATLAS experiment at the LHC. The sensitivity of the cross-sections to the gluon parton distribution function is explored.

JFKengine: A Jacobian and Forward Kinematics Generator

Energy Technology Data Exchange (ETDEWEB)

Fischer, K.N.

2003-02-13

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

Initiation of extension in South China continental margin during the active-passive margin transition: kinematic and thermochronological constraints

Science.gov (United States)

ZUO, Xuran; CHAN, Lung

2015-04-01

The southern South China Block is characterized by a widespread magmatic belt, prominent NE-striking fault zones and numerous rifted basins filled by Cretaceous-Eocene sediments. The geology denotes a transition from an active to a passive margin, which led to rapid modifications of crustal stress configuration and reactivation of older faults in this area. In this study, we used zircon fission-track dating (ZFT) and numerical modeling to examine the timing and kinematics of the active-passive margin transition. Our ZFT results on granitic plutons in the SW Cathaysia Block show two episodes of exhumation of the granitic plutons. The first episode, occurring during 170 Ma - 120 Ma, affected local parts of the Nanling Range. The second episode, a more regional exhumation event, occurred during 115 Ma - 70 Ma. Numerical geodynamic modeling was conducted to simulate the subduction between the paleo-Pacific plate and the South China Block. The modeling results could explain the observation based on ZFT data that exhumation of the granite-dominant Nanling Range occurred at an earlier time than the gneiss-dominant Yunkai Terrane. In addition to the difference in geology between Yunkai and Nanling, the heating from Jurassic-Early Cretaceous magmatism in the Nanling Range may have softened the upper crust, causing the area to exhume more readily. Numerical modeling results also indicate that (1) high slab dip angle, high geothermal gradient of lithosphere and low convergence velocity favor the subduction process and the reversal of crustal stress state from compression to extension in the upper plate; (2) the late Mesozoic magmatism in South China was probably caused by a slab roll-back; and (3) crustal extension could have occurred prior to the cessation of plate subduction. The inversion of stress regime in the continental crust from compression to crustal extension has shed light on the geological condition producing the red bed basins during Late Cretaceous

Technique, muscle activity and kinematic differences in young adults texting on mobile phones.

Science.gov (United States)

Gustafsson, Ewa; Johnson, Peter W; Lindegård, Agneta; Hagberg, Mats

2011-05-01

The aim of this study was to investigate whether there are differences in technique between young adults with and without musculoskeletal symptoms when using a mobile phone for texting and whether there are differences in muscle activity and kinematics between different texting techniques. A total of 56 young adults performed a standardised texting task on a mobile phone. Their texting techniques were registered using an observation protocol. The muscular activity in six muscles in the right forearm/hand and both shoulders were registered by surface electromyography and the thumb abduction/adduction and flexion/extension were registered using a biaxial electrogoniometer. Differences in texting techniques were found between the symptomatic and the asymptomatic group, with a higher proportion of sitting with back support and forearm support and with a neutral head position in the asymptomatic group. Differences in muscle activity and kinematics were also found between different texting techniques. The differences in texting technique between symptomatic and asymptomatic subjects cannot be explained by them having symptoms but may be a possible contribution to their symptoms. STATEMENT OF RELEVANCE: There has been a dramatically increased use of mobile phones for texting especially among young people during the last years. A better understanding of the physical exposure associated with the intensive use is important in order to prevent the development of musculoskeletal disorders and decreased work ability related to this use.

Correlation of neural activity with behavioral kinematics reveals distinct sensory encoding and evidence accumulation processes during active tactile sensing.

Science.gov (United States)

Delis, Ioannis; Dmochowski, Jacek P; Sajda, Paul; Wang, Qi

2018-03-23

Many real-world decisions rely on active sensing, a dynamic process for directing our sensors (e.g. eyes or fingers) across a stimulus to maximize information gain. Though ecologically pervasive, limited work has focused on identifying neural correlates of the active sensing process. In tactile perception, we often make decisions about an object/surface by actively exploring its shape/texture. Here we investigate the neural correlates of active tactile decision-making by simultaneously measuring electroencephalography (EEG) and finger kinematics while subjects interrogated a haptic surface to make perceptual judgments. Since sensorimotor behavior underlies decision formation in active sensing tasks, we hypothesized that the neural correlates of decision-related processes would be detectable by relating active sensing to neural activity. Novel brain-behavior correlation analysis revealed that three distinct EEG components, localizing to right-lateralized occipital cortex (LOC), middle frontal gyrus (MFG), and supplementary motor area (SMA), respectively, were coupled with active sensing as their activity significantly correlated with finger kinematics. To probe the functional role of these components, we fit their single-trial-couplings to decision-making performance using a hierarchical-drift-diffusion-model (HDDM), revealing that the LOC modulated the encoding of the tactile stimulus whereas the MFG predicted the rate of information integration towards a choice. Interestingly, the MFG disappeared from components uncovered from control subjects performing active sensing but not required to make perceptual decisions. By uncovering the neural correlates of distinct stimulus encoding and evidence accumulation processes, this study delineated, for the first time, the functional role of cortical areas in active tactile decision-making. Copyright © 2018 Elsevier Inc. All rights reserved.

Kinematic matrix theory and universalities in self-propellers and active swimmers.

Science.gov (United States)

Nourhani, Amir; Lammert, Paul E; Borhan, Ali; Crespi, Vincent H

2014-06-01

We describe an efficient and parsimonious matrix-based theory for studying the ensemble behavior of self-propellers and active swimmers, such as nanomotors or motile bacteria, that are typically studied by differential-equation-based Langevin or Fokker-Planck formalisms. The kinematic effects for elementary processes of motion are incorporated into a matrix, called the "kinematrix," from which we immediately obtain correlators and the mean and variance of angular and position variables (and thus effective diffusivity) by simple matrix algebra. The kinematrix formalism enables us recast the behaviors of a diverse range of self-propellers into a unified form, revealing universalities in their ensemble behavior in terms of new emergent time scales. Active fluctuations and hydrodynamic interactions can be expressed as an additive composition of separate self-propellers.

Continuous and simultaneous estimation of finger kinematics using inputs from an EMG-to-muscle activation model.

Science.gov (United States)

Ngeo, Jimson G; Tamei, Tomoya; Shibata, Tomohiro

2014-08-14

Surface electromyography (EMG) signals are often used in many robot and rehabilitation applications because these reflect motor intentions of users very well. However, very few studies have focused on the accurate and proportional control of the human hand using EMG signals. Many have focused on discrete gesture classification and some have encountered inherent problems such as electro-mechanical delays (EMD). Here, we present a new method for estimating simultaneous and multiple finger kinematics from multi-channel surface EMG signals. In this study, surface EMG signals from the forearm and finger kinematic data were extracted from ten able-bodied subjects while they were tasked to do individual and simultaneous multiple finger flexion and extension movements in free space. Instead of using traditional time-domain features of EMG, an EMG-to-Muscle Activation model that parameterizes EMD was used and shown to give better estimation performance. A fast feed forward artificial neural network (ANN) and a nonparametric Gaussian Process (GP) regressor were both used and evaluated to estimate complex finger kinematics, with the latter rarely used in the other related literature. The estimation accuracies, in terms of mean correlation coefficient, were 0.85 ± 0.07, 0.78 ± 0.06 and 0.73 ± 0.04 for the metacarpophalangeal (MCP), proximal interphalangeal (PIP) and the distal interphalangeal (DIP) finger joint DOFs, respectively. The mean root-mean-square error in each individual DOF ranged from 5 to 15%. We show that estimation improved using the proposed muscle activation inputs compared to other features, and that using GP regression gave better estimation results when using fewer training samples. The proposed method provides a viable means of capturing the general trend of finger movements and shows a good way of estimating finger joint kinematics using a muscle activation model that parameterizes EMD. The results from this study demonstrates a potential control

Treatment of photon radiation in kinematics fits at future e{sup +}e{sup -} colliders

Energy Technology Data Exchange (ETDEWEB)

Beckmann, M.; List, J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); List, B. [Hamburg Univ. (Germany). Inst. fuer Experimentalphysik

2010-05-15

Kinematic fitting, where constraints such as energy and momentum conservation are imposed on measured four-vectors of jets and leptons, is an important tool to improve the resolution in high-energy physics experiments. At future e{sup +}e{sup -} colliders, photon radiation parallel to the beam carrying away large amounts of energy and momentum will become a challenge for kinematic fitting. A photon with longitudinal momentum p{sub z,{gamma}} ({eta}) is introduced, which is parametrized such that {eta} follows a normal distribution. In the fit, {eta} is treated as having a measured value of zero, which corresponds to p{sub z,{gamma}}, = 0. As a result, fits with constraints on energy and momentum conservation converge well even in the presence of a highly energetic photon, while the resolution of fits without such a photon is retained. A fully simulated and reconstructed e{sup +}e{sup -}{yields}q anti qq anti q event sample at {radical}(s)=500 GeV is used to investigate the performance of this method under realistic conditions, as expected at the International Linear Collider. (orig.)

Observational Constraints on Cloud Feedbacks: The Role of Active Satellite Sensors

Science.gov (United States)

Winker, David; Chepfer, Helene; Noel, Vincent; Cai, Xia

2017-11-01

Cloud profiling from active lidar and radar in the A-train satellite constellation has significantly advanced our understanding of clouds and their role in the climate system. Nevertheless, the response of clouds to a warming climate remains one of the largest uncertainties in predicting climate change and for the development of adaptions to change. Both observation of long-term changes and observational constraints on the processes responsible for those changes are necessary. We review recent progress in our understanding of the cloud feedback problem. Capabilities and advantages of active sensors for observing clouds are discussed, along with the importance of active sensors for deriving constraints on cloud feedbacks as an essential component of a global climate observing system.

Effects of therapy on masseter activity and chewing kinematics in patients with unilateral posterior crossbite.

Science.gov (United States)

Piancino, Maria Grazia; Falla, Deborah; Merlo, Andrea; Vallelonga, Teresa; de Biase, Corrado; Dalessandri, Domenico; Debernardi, Cesare

2016-07-01

To describe the effects of therapy on masseter activity and chewing kinematic in patients with unilateral posterior crossbite (UPC). Fifty children (age: mean ± SD: 9.1 ± 2.3 years) with UPC (34 on the right side, 16 on the left side) and twenty children (age: 9.5 ± 2.6 years) with normal occlusion were selected for the study. The mandibular motion and the muscular activity during chewing soft and hard boli were simultaneously recorded, before and after correction with function generating bite, after a mean treatment time of 7.3 ± 2.4 months plus the retention time of 5-6 months. The percentage of reverse cycles and the percent difference between ipsilateral and contralateral peaks of the masseter electromyography envelopes were computed. Before therapy, the percentage of reverse cycles during chewing on the crossbite side was greater in patients than in controls (Preverse chewing patterns. The previous altered muscular activation corresponded to the altered kinematics of reverse chewing cycles that might be considered a useful indicator of the severity of the masticatory function involvement. Copyright © 2016 Elsevier Ltd. All rights reserved.

The brown dwarf kinematics project

Science.gov (United States)

Faherty, Jackie K.

2010-10-01

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

Analysis and experimental kinematics of a skid-steering wheeled robot based on a laser scanner sensor.

Science.gov (United States)

Wang, Tianmiao; Wu, Yao; Liang, Jianhong; Han, Chenhao; Chen, Jiao; Zhao, Qiteng

2015-04-24

Skid-steering mobile robots are widely used because of their simple mechanism and robustness. However, due to the complex wheel-ground interactions and the kinematic constraints, it is a challenge to understand the kinematics and dynamics of such a robotic platform. In this paper, we develop an analysis and experimental kinematic scheme for a skid-steering wheeled vehicle based-on a laser scanner sensor. The kinematics model is established based on the boundedness of the instantaneous centers of rotation (ICR) of treads on the 2D motion plane. The kinematic parameters (the ICR coefficient , the path curvature variable and robot speed ), including the effect of vehicle dynamics, are introduced to describe the kinematics model. Then, an exact but costly dynamic model is used and the simulation of this model's stationary response for the vehicle shows a qualitative relationship for the specified parameters and . Moreover, the parameters of the kinematic model are determined based-on a laser scanner localization experimental analysis method with a skid-steering robotic platform, Pioneer P3-AT. The relationship between the ICR coefficient and two physical factors is studied, i.e., the radius of the path curvature and the robot speed . An empirical function-based relationship between the ICR coefficient of the robot and the path parameters is derived. To validate the obtained results, it is empirically demonstrated that the proposed kinematics model significantly improves the dead-reckoning performance of this skid-steering robot.

Inverse relationship between the complexity of midfoot kinematics and muscle activation in patients with medial tibial stress syndrome

DEFF Research Database (Denmark)

Rathleff, M S; Samani, Afshin; Olesen, C G

2011-01-01

Medial tibial stress syndrome is a common overuse injury characterized by pain located on the medial side of the lower leg during weight bearing activities such as gait. The purpose of this study was to apply linear and nonlinear methods to compare the structure of variability of midfoot kinematics...... and surface electromyographic (SEMG) signals between patients with medial tibial stress syndrome and healthy controls during gait. Fourteen patients diagnosed with medial tibial stress syndrome and 11 healthy controls were included from an orthopaedic clinic. SEMG from tibialis anterior and the soleus muscles...... as well as midfoot kinematics were recorded during 20 consecutive gait cycles. Permuted sample entropy and permutation entropy were used as a measure of complexity from SEMG signals and kinematics. SEMG signals in patients with medial tibial stress syndrome were characterized by higher structural...

The influence of different footwear on 3-D kinematics and muscle activation during the barbell back squat in males.

Science.gov (United States)

Sinclair, Jonathan; McCarthy, Derek; Bentley, Ian; Hurst, Howard Thomas; Atkins, Stephen

2015-01-01

The barbell back squat is commonly used by athletes participating in resistance training. The barbell squat is typically performed using standard athletic shoes, or specially designed weightlifting footwear, although there are now a large number of athletes who prefer to squat barefoot or in barefoot-inspired footwear. This study aimed to determine how these footwear influence 3-D kinematics and muscle activation potentials during the barbell back squat. Fourteen experienced male participants completed squats at 70% 1 rep max in each footwear condition. 3-D kinematics from the torso, hip, knee and ankle were measured using an eight-camera motion analysis system. In addition, electromyographical (EMG) measurements were obtained from the rectus femoris, tibialis anterior, gastrocnemius, erector spinae and biceps femoris muscles. EMG parameters and joint kinematics were compared between footwear using repeated-measures analyses of variance. Participants were also asked to subjectively rate which footwear they preferred when performing their squat lifts; this was examined a chi-squared test. The kinematic analysis indicated that, in comparison to barefoot the running shoe was associated with increased squat depth, knee flexion and rectus femoris activation. The chi-squared test was significant and showed that participants preferred to squat barefoot. This study supports anecdotal evidence of athletes who prefer to train barefoot or in barefoot-inspired footwear although no biomechanical evidence was found to support this notion.

Effect of weight and frontal area of external telemetry packages on the kinematics, activity levels and swimming performance of small-bodied sharks.

Science.gov (United States)

Bouyoucos, I A; Suski, C D; Mandelman, J W; Brooks, E J

2017-05-01

This study sought to observe the effects of submerged weight and frontal cross-sectional area of external telemetry packages on the kinematics, activity levels and swimming performance of small-bodied juvenile sharks, using lemon sharks Negaprion brevirostris (60-80 cm total length, L T ) as a model species. Juveniles were observed free-swimming in a mesocosm untagged and with small and large external accelerometer packages that increased frontal cross-sectional area of the animals and their submerged weight. Despite adhering to widely used standards for tag mass, the presence of an external telemetry package altered swimming kinematics, activity levels and swimming performance of juvenile N. brevirostris relative to untagged individuals, suggesting that tag mass is not a suitable standalone metric of device suitability. Changes in swimming performance could not be detected from tail-beat frequency, which suggests that tail-beat frequency is an unsuitable standalone metric of swimming performance for small N. brevirostris. Lastly, sharks experienced treatment-specific changes in activity level and swimming kinematics from morning to afternoon observation. Therefore, the presence of external telemetry packages altered the kinematics, activity levels and swimming performance of small young-of-the-year N. brevirostris and these data may therefore be relevant to other similar-sized juveniles of other shark species. © 2017 The Fisheries Society of the British Isles.

Kinematic mounting systems for NSLS beamlines and experiments

International Nuclear Information System (INIS)

Oversluizen, T.; Stoeber, W.; Johnson, E.D.

1991-01-01

Methods for kinematically mounting equipment are well established, but applications at synchrotron radiation facilities are subject to constraints not always encountered in more traditional laboratory settings. Independent position adjustment of beamline components can have significant benefits in terms of minimizing time spent aligning, and maximizing time spent acquiring data. In this paper, we use examples taken from beamlines at the NSLS to demonstrate approaches for optimization of the reproducibility, stability, excursion, and set-up time for various situations. From our experience, we extract general principles which we hope will be useful for workers at other synchrotron radiation facilities. 7 refs., 4 figs

Effect of Auditory Constraints on Motor Learning Depends on Stage of Recovery Post Stroke

Directory of Open Access Journals (Sweden)

Viswanath eAluru

2014-06-01

Full Text Available In order to develop evidence-based rehabilitation protocols post stroke, one must first reconcile the vast heterogeneity in the post-stroke population and develop protocols to facilitate motor learning in the various subgroups. The main purpose of this study is to show that auditory constraints interact with the stage of recovery post stroke to influence motor learning. We characterized the stages of upper limb recovery using task-based kinematic measures in twenty subjects with chronic hemiparesis, and used a bimanual wrist extension task using a custom-made wrist trainer to facilitate learning of wrist extension in the paretic hand under four auditory conditions: 1 without auditory cueing; 2 to non-musical happy sounds; 3 to self-selected music; and 4 to a metronome beat set at a comfortable tempo. Two bimanual trials (15 s each were followed by one unimanual trial with the paretic hand over six cycles under each condition. Clinical metrics, wrist and arm kinematics and electromyographic activity were recorded. Hierarchical cluster analysis with the Mahalanobis metric based on baseline speed and extent of wrist movement stratified subjects into three distinct groups which reflected their stage of recovery: spastic paresis, spastic co-contraction, and minimal paresis. In spastic paresis, the metronome beat increased wrist extension, but also increased muscle co-activation across the wrist. In contrast, in spastic co-contraction, no auditory stimulation increased wrist extension and reduced co-activation. In minimal paresis, wrist extension did not improve under any condition. The results suggest that auditory task constraints interact with stage of recovery during motor learning after stroke, perhaps due to recruitment of distinct neural substrates over the course of recovery. The findings advance our understanding of the mechanisms of progression of motor recovery and lay the foundation for personalized treatment algorithms post stroke.

Physical activity participation and constraints among athletic training students.

Science.gov (United States)

Stanek, Justin; Rogers, Katherine; Anderson, Jordan

2015-02-01

Researchers have examined the physical activity (PA) habits of certified athletic trainers; however, none have looked specifically at athletic training students. To assess PA participation and constraints to participation among athletic training students. Cross-sectional study. Entry-level athletic training education programs (undergraduate and graduate) across the United States. Participants were 1125 entry-level athletic training students. Self-reported PA participation, including a calculated PA index based on a typical week. Leisure constraints and demographic data were also collected. Only 22.8% (252/1105) of athletic training students were meeting the American College of Sports Medicine recommendations for PA through moderate-intensity cardiorespiratory exercise. Although 52.3% (580/1105) were meeting the recommendations through vigorous-intensity cardiorespiratory exercise, 60.5% (681/1125) were meeting the recommendations based on the combined total of moderate or vigorous cardiorespiratory exercise. In addition, 57.2% (643/1125) of respondents met the recommendations for resistance exercise. Exercise habits of athletic training students appear to be better than the national average and similar to those of practicing athletic trainers. Students reported structural constraints such as lack of time due to work or studies as the most significant barrier to exercise participation. Athletic training students experienced similar constraints to PA participation as practicing athletic trainers, and these constraints appeared to influence their exercise participation during their entry-level education. Athletic training students may benefit from a greater emphasis on work-life balance during their entry-level education to promote better health and fitness habits.

Self-aligning exoskeleton hip joint: Kinematic design with five revolute, three prismatic and one ball joint.

Science.gov (United States)

Beil, Jonas; Marquardt, Charlotte; Asfour, Tamim

2017-07-01

Kinematic compatibility is of paramount importance in wearable robotic and exoskeleton design. Misalignments between exoskeletons and anatomical joints of the human body result in interaction forces which make wearing the exoskeleton uncomfortable and even dangerous for the human. In this paper we present a kinematically compatible design of an exoskeleton hip to reduce kinematic incompatibilities, so called macro- and micro-misalignments, between the human's and exoskeleton's joint axes, which are caused by inter-subject variability and articulation. The resulting design consists of five revolute, three prismatic and one ball joint. Design parameters such as range of motion and joint velocities are calculated based on the analysis of human motion data acquired by motion capture systems. We show that the resulting design is capable of self-aligning to the human hip joint in all three anatomical planes during operation and can be adapted along the dorsoventral and mediolateral axis prior to operation. Calculation of the forward kinematics and FEM-simulation considering kinematic and musculoskeletal constraints proved sufficient mobility and stiffness of the system regarding the range of motion, angular velocity and torque admissibility needed to provide 50 % assistance for an 80 kg person.

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

Science.gov (United States)

Plummer, Hillary A; Oliver, Gretchen D

2014-01-01

The purpose of this study was to determine the relationship between gluteal muscle activation and pelvis and trunk kinematics when catchers throw to second base. Forty-two baseball and softball catchers (14.74 ± 4.07 years; 161.85 ± 15.24 cm; 63.38 ± 19.98 kg) participated in this study. Muscle activity of the bilateral gluteus maximus and medius as well as pelvis and trunk kinematics throughout the throwing motion were analyzed. It was discovered that at foot contact, there were 2 significant inverse relationships between stride leg gluteus maximus activity and pelvis axial rotation (r = -0.31, r2 = 0.10, p = 0.05), and between trunk axial rotation and pelvis lateral flexion (r = -0.34, r2= 0.12, p = 0.03). In addition, at foot contact, a significant positive relationship between the drive leg (throwing arm side) and trunk flexion (r = 0.33, r2 = 0.11, p = 0.04) was present. The results of this study provide evidence of gluteal activation both concentrically and eccentrically, in attempt to control the pelvis and trunk during the throwing motion of catchers. The gluteal muscles play a direct role in maintaining the stability of the pelvis, and catchers should incorporate strengthening of the entire lumbopelvic-hip complex into their training regimen. Incorporating concentric and eccentric gluteal exercises will help to improve musculoskeletal core stability, thereby assisting in upper extremity injury prevention.

Aging and rejuvenation of active matter under topological constraints

NARCIS (Netherlands)

Janssen, L.M.C.; Kaiser, A.; Löwen, H.W.

2017-01-01

The coupling of active, self-motile particles to topological constraints can give rise to novel non-equilibrium dynamical patterns that lack any passive counterpart. Here we study the behavior of self-propelled rods confined to a compact spherical manifold by means of Brownian dynamics simulations.

Reproducibility of kinematic measures of the thoracic spine, lumbar spine and pelvis during fast running.

Science.gov (United States)

Mason, D L; Preece, S J; Bramah, C A; Herrington, L C

2016-01-01

This study evaluated the reproducibility of the angular rotations of the thoracic spine, lumbar spine, pelvis and lower extremity during running. In addition, the study compared kinematic reproducibility between two methods for calculating kinematic trajectories: a six degrees of freedom (6DOF) approach and a global optimisation (GO) approach. With the first approach segments were treated independently, however with GO approach joint constraints were imposed to stop translation of adjacent segments. A total of 12 athletes were tested on two separate days whilst running over ground at a speed of 5.6ms(-1). The results demonstrated good between-day reproducibility for most kinematic parameters in the frontal and transverse planes with typical angular errors of 1.4-3°. Acceptable repeatability was also found in the sagittal plane. However, in this plane, although kinematic waveform shape was preserved between testing session, there were sometimes shifts in curve offset which lead to slightly higher angular errors, typically ranging from 1.9° to 3.5°. In general, the results demonstrated similar levels of reproducibility for both computational approaches (6DOF and, GO) and therefore suggest that GO may not lead to improved kinematic reproducibility during running. Copyright © 2013 Elsevier B.V. All rights reserved.

Activity and Kinematics of White Dwarf-M Dwarf Binaries from the SUPERBLINK Proper Motion Survey

International Nuclear Information System (INIS)

Skinner, Julie N.; Morgan, Dylan P.; West, Andrew A.; Lépine, Sébastien; Thorstensen, John R.

2017-01-01

We present an activity and kinematic analysis of high proper motion white dwarf-M dwarf binaries (WD+dMs) found in the SUPERBLINK survey, 178 of which are new identifications. To identify WD+dMs, we developed a UV–optical–IR color criterion and conducted a spectroscopic survey to confirm each candidate binary. For the newly identified systems, we fit the two components using model white dwarf spectra and M dwarf template spectra to determine physical parameters. We use H α chromospheric emission to examine the magnetic activity of the M dwarf in each system, and investigate how its activity is affected by the presence of a white dwarf companion. We find that the fraction of WD+dM binaries with active M dwarfs is significantly higher than their single M dwarf counterparts at early and mid-spectral types. We corroborate previous studies that find high activity fractions at both close and intermediate separations. At more distant separations, the binary fraction appears to approach the activity fraction for single M dwarfs. Using derived radial velocities and the proper motions, we calculate 3D space velocities for the WD+dMs in SUPERBLINK. For the entire SUPERBLINK WD+dMs, we find a large vertical velocity dispersion, indicating a dynamically hotter population compared to high proper motion samples of single M dwarfs. We compare the kinematics for systems with active M dwarfs and those with inactive M dwarfs, and find signatures of asymmetric drift in the inactive sample, indicating that they are drawn from an older population.

Activity and Kinematics of White Dwarf-M Dwarf Binaries from the SUPERBLINK Proper Motion Survey

Energy Technology Data Exchange (ETDEWEB)

Skinner, Julie N. [Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States); Morgan, Dylan P.; West, Andrew A. [Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States); Lépine, Sébastien [Department of Physics and Astronomy, Georgia State University, 25 Park Place NE, Atlanta, GA, 30303 (United States); Thorstensen, John R., E-mail: jskinner@bu.edu [Department of Physics and Astronomy, 6127 Wilder Laboratory, Dartmouth College, Hanover, NH 03755 (United States)

2017-09-01

We present an activity and kinematic analysis of high proper motion white dwarf-M dwarf binaries (WD+dMs) found in the SUPERBLINK survey, 178 of which are new identifications. To identify WD+dMs, we developed a UV–optical–IR color criterion and conducted a spectroscopic survey to confirm each candidate binary. For the newly identified systems, we fit the two components using model white dwarf spectra and M dwarf template spectra to determine physical parameters. We use H α chromospheric emission to examine the magnetic activity of the M dwarf in each system, and investigate how its activity is affected by the presence of a white dwarf companion. We find that the fraction of WD+dM binaries with active M dwarfs is significantly higher than their single M dwarf counterparts at early and mid-spectral types. We corroborate previous studies that find high activity fractions at both close and intermediate separations. At more distant separations, the binary fraction appears to approach the activity fraction for single M dwarfs. Using derived radial velocities and the proper motions, we calculate 3D space velocities for the WD+dMs in SUPERBLINK. For the entire SUPERBLINK WD+dMs, we find a large vertical velocity dispersion, indicating a dynamically hotter population compared to high proper motion samples of single M dwarfs. We compare the kinematics for systems with active M dwarfs and those with inactive M dwarfs, and find signatures of asymmetric drift in the inactive sample, indicating that they are drawn from an older population.

Kinematic space and wormholes

Energy Technology Data Exchange (ETDEWEB)

Zhang, Jian-dong [TianQin Research Center for Gravitational Physics, Sun Yat-sen University, Zhuhai 519082, Guangdong (China); Chen, Bin [Department of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter, 5 Yiheyuan Rd, Beijing 100871 (China); Center for High Energy Physics, Peking University, 5 Yiheyuan Rd, Beijing 100871 (China)

2017-01-23

The kinematic space could play a key role in constructing the bulk geometry from dual CFT. In this paper, we study the kinematic space from geometric points of view, without resorting to differential entropy. We find that the kinematic space could be intrinsically defined in the embedding space. For each oriented geodesic in the Poincaré disk, there is a corresponding point in the kinematic space. This point is the tip of the causal diamond of the disk whose intersection with the Poincaré disk determines the geodesic. In this geometric construction, the causal structure in the kinematic space can be seen clearly. Moreover, we find that every transformation in the SL(2,ℝ) leads to a geodesic in the kinematic space. In particular, for a hyperbolic transformation defining a BTZ black hole, it is a timelike geodesic in the kinematic space. We show that the horizon length of the static BTZ black hole could be computed by the geodesic length of corresponding points in the kinematic space. Furthermore, we discuss the fundamental regions in the kinematic space for the BTZ blackhole and multi-boundary wormholes.

Paleomagnetic constraints on the Cenozoic kinematic evolution of the Pamir plateau from the Western Kunlun Shan foreland

Science.gov (United States)

Li, Zhenyu; Ding, Lin; Lippert, Peter C.; Wei, Honghong

2013-09-01

Thick Cenozoic marine and terrestrial sediments are widely distributed along the perimeter of the Pamir plateau and provide valuable information on the kinematic evolution of the region. Here, we report new biostratigraphic and paleomagnetic results from the piedmont of the Western Kunlun Shan to constrain the magnitude and timing of vertical-axis rotations along the eastern margin of the Pamir. Sampling sites were selected by rock formations and ages, which are based on previous field mapping and on litholostratigraphic and biostratigraphic work presented here. Thermomagnetic analysis, step-wise thermal demagnetization behavior, and positive field tests all suggest that the characteristic remanent magnetization (ChRM) directions most probably have a primary detrital and chemical origin. Our results indicate variable, minor, but in some intervals significant vertical axis rotations with respect to a stable Asian reference frame. This pattern of rotations is similar to paleomagnetic data reported in previously published studies from the Eastern Pamir foreland. In contrast, published paleomagnetic data from the Western Pamir foreland consistently indicate significant CCW rotations within that region. Collectively, these results challenge simple oroclinal bending models for the origin of the Pamir salient, and instead are more consistent with an asymmetric "half-orocline" kinematic model in which the curvature of the Western Pamir is the product of a combination of lithospheric bending of an originally quasi-linear mountain belt and radial thrusting, and the subdued curvature of the eastern edge of the plateau is the result of lateral translation of the Pamir plateau northward past Tibet and Tarim along the Kashgar-Yecheng transfer system. Our results are consistent with activity on the Kashgar-Yecheng transfer system in the Early Miocene.

Kinematics analysis of a novel planar parallel manipulator with kinematic redundancy

Energy Technology Data Exchange (ETDEWEB)

Qu, Haibo; Guo, Sheng [Beijing Jiaotong University, Beijing (China)

2017-04-15

In this paper, a novel planar parallel manipulator with kinematic redundancy is proposed. First, the Degrees of freedom (DOF) of the whole parallel manipulator and the Relative DOF (RDOF) between the moving platform and fixed base are studied. The results indicate that the proposed mechanism is kinematically redundant. Then, the kinematics, Jacobian matrices and workspace of this proposed parallel manipulator with kinematic redundancy are analyzed. Finally, the statics simulation of the proposed parallel manipulator is performed. The obtained stress and displacement distribution can be used to determine the easily destroyed place in the mechanism configurations.

Kinematics analysis of a novel planar parallel manipulator with kinematic redundancy

International Nuclear Information System (INIS)

Qu, Haibo; Guo, Sheng

2017-01-01

In this paper, a novel planar parallel manipulator with kinematic redundancy is proposed. First, the Degrees of freedom (DOF) of the whole parallel manipulator and the Relative DOF (RDOF) between the moving platform and fixed base are studied. The results indicate that the proposed mechanism is kinematically redundant. Then, the kinematics, Jacobian matrices and workspace of this proposed parallel manipulator with kinematic redundancy are analyzed. Finally, the statics simulation of the proposed parallel manipulator is performed. The obtained stress and displacement distribution can be used to determine the easily destroyed place in the mechanism configurations

Kinematics, muscular activity and propulsion in gopher snakes

Science.gov (United States)

Moon; Gans

1998-10-01

Previous studies have addressed the physical principles and muscular activity patterns underlying terrestrial lateral undulation in snakes, but not the mechanism by which muscular activity produces curvature and propulsion. In this study, we used synchronized electromyography and videography to examine the muscular basis and propulsive mechanism of terrestrial lateral undulation in gopher snakes Pituophis melanoleucus affinis. Specifically, we used patch electrodes to record from the semispinalis, longissimus dorsi and iliocostalis muscles in snakes pushing against one or more pegs. Axial bends propagate posteriorly along the body and contact the pegs at or immediately posterior to an inflection of curvature, which then reverses anterior to the peg. The vertebral column bends broadly around a peg, whereas the body wall bends sharply and asymmetrically around the anterior surface of the peg. The epaxial muscles are always active contralateral to the point of contact with a peg; they are activated slightly before or at the point of maximal convexity and deactivated variably between the inflection point and the point of maximal concavity. This pattern is consistent with muscular shortening and the production of axial bends, although variability in the pattern indicates that other muscles may affect the mechanics of the epaxial muscles. The kinematic and motor patterns in snakes crawling against experimentally increased drag indicated that forces are produced largely by muscles that are active in the axial bend around each peg, rather than by distant muscles from which the forces might be transmitted by connective tissues. At each point of force exertion, the propulsive mechanism of terrestrial lateral undulation may be modeled as a type of cam-follower, in which continuous bending of the trunk around the peg produces translation of the snake.

Relativistic Kinematics

OpenAIRE

Sahoo, Raghunath

2016-01-01

This lecture note covers Relativistic Kinematics, which is very useful for the beginners in the field of high-energy physics. A very practical approach has been taken, which answers "why and how" of the kinematics useful for students working in the related areas.

Decoherence and discrete symmetries in deformed relativistic kinematics

Science.gov (United States)

Arzano, Michele

2018-01-01

Models of deformed Poincaré symmetries based on group valued momenta have long been studied as effective modifications of relativistic kinematics possibly capturing quantum gravity effects. In this contribution we show how they naturally lead to a generalized quantum time evolution of the type proposed to model fundamental decoherence for quantum systems in the presence of an evaporating black hole. The same structures which determine such generalized evolution also lead to a modification of the action of discrete symmetries and of the CPT operator. These features can in principle be used to put phenomenological constraints on models of deformed relativistic symmetries using precision measurements of neutral kaons.

Ordered kinematic endpoints for 5-body cascade decays

Energy Technology Data Exchange (ETDEWEB)

Klimek, Matthew D. [Theory Group, Department of Physics and Texas Cosmology Center,University of Texas at Austin, 2515 Speedway, Stop C1608, Austin, TX, 78712 (United States)

2016-12-23

We present expressions for the kinematic endpoints of 5-body cascade decay chains proceeding through all possible combinations of 2-body and 3-body decays, with one stable invisible particle in the final decay stage. When an invariant mass can be formed in multiple ways by choosing different final state particles from a common vertex, we introduce techniques for finding the sub-leading endpoints for all indistinguishable versions of the invariant mass. In contrast to short decay chains, where sub-leading endpoints are linearly related to the leading endpoints, we find that in 5-body decays, they provide additional independent constraints on the mass spectrum.

Effects of thigh holster use on kinematics and kinetics of active duty police officers.

Science.gov (United States)

Larsen, Louise Bæk; Tranberg, Roy; Ramstrand, Nerrolyn

2016-08-01

Body armour, duty belts and belt mounted holsters are standard equipment used by the Swedish police and have been shown to affect performance of police specific tasks, to decrease mobility and to potentially influence back pain. This study aimed to investigate the effects on gait kinematics and kinetics associated with use of an alternate load carriage system incorporating a thigh holster. Kinematic, kinetic and temporospatial data were collected using three dimensional gait analysis. Walking tests were conducted with nineteen active duty police officers under three different load carriage conditions: a) body armour and duty belt, b) load bearing vest, body armour and thigh holster and c) no equipment (control). No significant differences between testing conditions were found for temporospatial parameters. Range of trunk rotation was reduced for both load carriage conditions compared to the control condition (p<0.017). Range of hip rotation was more similar to the control condition when wearing thigh holster rather than the belt mounted hip holster (p<0.017). Moments and powers for both left and right ankles were significantly greater for both of the load carriage conditions compared to the control condition (p<0.017). This study confirms that occupational loads carried by police have a significant effect on gait kinematics and kinetics. Although small differences were observed between the two load carriage conditions investigated in this study, results do not overwhelmingly support selection of one design over the other. Copyright © 2016 Elsevier Ltd. All rights reserved.

Some kinematics and dynamics from a superposition of two axisymmetric stellar systems

International Nuclear Information System (INIS)

Cubarsi i Morera, R.

1990-01-01

Some kinematic and dynamic implications of a superposition of two stellar systems are studied. In the general case of a stellar system in nonsteady states, Chandrasekhar's axially symmetrical model has been adopted for each one of the subsystems. The solution obtained for the potential function provides some kinematical constraints between the subsystems. These relationships are derived using the partial centered moments of the velocity distribution and the subcentroid velocities in order to study the velocity distribution. These relationships are used to prove that, only in a stellar system where the potential function is assumed to be stationary, the relative movement of the local subcentroids (not only in rotation), the vertex deviation phenomenon, and the whole set of the second-order-centered moments may be explained. A qualitative verification with three stellar samples in the solar neighborhood is carried out. 41 refs

Nordic hamstring exercise training alters knee joint kinematics and hamstring activation patterns in young men.

Science.gov (United States)

Delahunt, Eamonn; McGroarty, Mark; De Vito, Giuseppe; Ditroilo, Massimiliano

2016-04-01

To investigate the kinematic and muscle activation adaptations during performance of the Nordic hamstring exercise (NHE) to a 6-week eccentric hamstring training programme using the NHE as the sole mode of exercise. Twenty-nine healthy males were randomly allocated to a control (CG) or intervention (IG) group. The IG participated in a 6-week eccentric hamstring exercise programme using the NHE. The findings of the present study were that a 6-week eccentric hamstring training programme improved eccentric hamstring muscle strength (202.4 vs. 177.4 nm, p = 0.0002, Cohen's d = 0.97) and optimized kinematic (longer control of the forward fall component of the NHE, 68.1° vs. 73.7°, p = 0.022, Cohen's d = 0.90) and neuromuscular parameters (increased electromyographic activity of the hamstrings, 83.2 vs. 56.6 % and 92.0 vs. 54.2 %, p 1.25) associated with NHE performance. This study provides some insight into potential mechanisms by which an eccentric hamstring exercise programme utilizing the NHE as the mode of exercise may result in an improvement in hamstring muscle control during eccentric contractions.

Constraint-induced movement therapy improves upper limb activity and participation in hemiplegic cerebral palsy: a systematic review

Directory of Open Access Journals (Sweden)

Hsiu-Ching Chiu

2016-07-01

Full Text Available Questions: Does constraint-induced movement therapy improve activity and participation in children with hemiplegic cerebral palsy? Does it improve activity and participation more than the same dose of upper limb therapy without restraint? Is the effect of constraint-induced movement therapy related to the duration of intervention or the age of the children? Design: Systematic review of randomised trials with meta-analysis. Participants: Children with hemiplegic cerebral palsy with any level of motor disability. Intervention: The experimental group received constraint-induced movement therapy (defined as restraint of the less affected upper limb during supervised activity practice of the more affected upper limb. The control group received no intervention, sham intervention, or the same dose of upper limb therapy. Outcome measures: Measures of upper limb activity and participation were used in the analysis. Results: Constraint-induced movement therapy was more effective than no/sham intervention in terms of upper limb activity (SMD 0.63, 95% CI 0.20 to 1.06 and participation (SMD 1.21, 95% CI 0.41 to 2.02. However, constraint-induced movement therapy was no better than the same dose of upper limb therapy without restraint either in terms of upper limb activity (SMD 0.05, 95% CI –0.21 to 0.32 or participation (SMD –0.02, 95% CI –0.34 to 0.31. The effect of constraint-induced movement therapy was not related to the duration of intervention or the age of the children. Conclusions: This review suggests that constraint-induced movement therapy is more effective than no intervention, but no more effective than the same dose of upper limb practice without restraint. Registration: PROSPERO CRD42015024665. [Chiu H-C, Ada L (2016 Constraint-induced movement therapy improves upper limb activity and participation in hemiplegic cerebral palsy: a systematic review. Journal of Physiotherapy 62: 130–137

Activity and Kinematics of White Dwarf-M Dwarf Binaries from the SUPERBLINK Proper Motion Survey

Science.gov (United States)

Skinner, Julie N.; Morgan, Dylan P.; West, Andrew A.; Lépine, Sébastien; Thorstensen, John R.

2017-09-01

We present an activity and kinematic analysis of high proper motion white dwarf-M dwarf binaries (WD+dMs) found in the SUPERBLINK survey, 178 of which are new identifications. To identify WD+dMs, we developed a UV-optical-IR color criterion and conducted a spectroscopic survey to confirm each candidate binary. For the newly identified systems, we fit the two components using model white dwarf spectra and M dwarf template spectra to determine physical parameters. We use Hα chromospheric emission to examine the magnetic activity of the M dwarf in each system, and investigate how its activity is affected by the presence of a white dwarf companion. We find that the fraction of WD+dM binaries with active M dwarfs is significantly higher than their single M dwarf counterparts at early and mid-spectral types. We corroborate previous studies that find high activity fractions at both close and intermediate separations. At more distant separations, the binary fraction appears to approach the activity fraction for single M dwarfs. Using derived radial velocities and the proper motions, we calculate 3D space velocities for the WD+dMs in SUPERBLINK. For the entire SUPERBLINK WD+dMs, we find a large vertical velocity dispersion, indicating a dynamically hotter population compared to high proper motion samples of single M dwarfs. We compare the kinematics for systems with active M dwarfs and those with inactive M dwarfs, and find signatures of asymmetric drift in the inactive sample, indicating that they are drawn from an older population. Based on observations obtained at the MDM Observatory operated by Dartmouth College, Columbia University, The Ohio State University, and the University of Michigan.

Constraint treatment techniques and parallel algorithms for multibody dynamic analysis. Ph.D. Thesis

Science.gov (United States)

Chiou, Jin-Chern

1990-01-01

Computational procedures for kinematic and dynamic analysis of three-dimensional multibody dynamic (MBD) systems are developed from the differential-algebraic equations (DAE's) viewpoint. Constraint violations during the time integration process are minimized and penalty constraint stabilization techniques and partitioning schemes are developed. The governing equations of motion, a two-stage staggered explicit-implicit numerical algorithm, are treated which takes advantage of a partitioned solution procedure. A robust and parallelizable integration algorithm is developed. This algorithm uses a two-stage staggered central difference algorithm to integrate the translational coordinates and the angular velocities. The angular orientations of bodies in MBD systems are then obtained by using an implicit algorithm via the kinematic relationship between Euler parameters and angular velocities. It is shown that the combination of the present solution procedures yields a computationally more accurate solution. To speed up the computational procedures, parallel implementation of the present constraint treatment techniques, the two-stage staggered explicit-implicit numerical algorithm was efficiently carried out. The DAE's and the constraint treatment techniques were transformed into arrowhead matrices to which Schur complement form was derived. By fully exploiting the sparse matrix structural analysis techniques, a parallel preconditioned conjugate gradient numerical algorithm is used to solve the systems equations written in Schur complement form. A software testbed was designed and implemented in both sequential and parallel computers. This testbed was used to demonstrate the robustness and efficiency of the constraint treatment techniques, the accuracy of the two-stage staggered explicit-implicit numerical algorithm, and the speed up of the Schur-complement-based parallel preconditioned conjugate gradient algorithm on a parallel computer.

Rational kinematics

CERN Document Server

Angeles, Jorge

1988-01-01

A rational study of kinematics is a treatment of the subject based on invariants, i.e., quantities that remain essentially unchanged under a change of observer. An observer is understood to be a reference frame supplied with a clock (Truesdell 1966). This study will therefore include an introduction to invariants. The language of these is tensor analysis and multilinear algebra, both of which share many isomorphic relations, These subjects are treated in full detail in Ericksen (1960) and Bowen and Wang (1976), and hence will not be included here. Only a short account of notation and definitions will be presented. Moreover, definitions and basic concepts pertaining to the kinematics of rigid bodies will be also included. Although the kinematics of rigid bodies can be regarded as a particular case of the kinematics of continua, the former deserves attention on its own merits for several reasons. One of these is that it describes locally the motions undergone by continua. Another reason is that a whole area of ...

Dose exposure work planning using DMU kinematics tools

International Nuclear Information System (INIS)

Rosli Darmawan

2010-01-01

The study on the possibility of using DMU Kinematics module in CAE tools for dose exposure work planning was carried out. A case scenario was created using 3D CAD software and transferred to DMU Kinematics module in CAE software. A work plan was created using DMU Kinematics tools and animated to simulate a real time scenario. Data on the phantom position against the radioactive source was collected by activating positioning sensors in the module. The data was used to estimate dose rate exposure for the phantom. The results can be used to plan the safest and optimum procedures in carrying out the radiation related task. (author)

Can co-activation reduce kinematic variability? A simulation study.

NARCIS (Netherlands)

Selen, L.P.J.; Beek, P.J.; van Dieen, J.H.

2005-01-01

Impedance modulation has been suggested as a means to suppress the effects of internal 'noise' on movement kinematics. We investigated this hypothesis in a neuro-musculo-skeletal model. A prerequisite is that the muscle model produces realistic force variability. We found that standard Hill-type

Effects of modified constraint-induced movement therapy on reach-to-grasp movements and functional performance after chronic stroke: a randomized controlled study.

Science.gov (United States)

Lin, K-C; Wu, C-Y; Wei, T-H; Lee, C-Y; Liu, J-S

2007-12-01

To evaluate changes in (1) motor control characteristics of the hemiparetic hand during the performance of a functional reach-to-grasp task and (2) functional performance of daily activities in patients with stroke treated with modified constraint-induced movement therapy. Two-group randomized controlled trial with pretreatment and posttreatment measures. Rehabilitation clinics. Thirty-two chronic stroke patients (21 men, 11 women; mean age=57.9 years, range=43-81 years) 13-26 months (mean 16.3 months) after onset of a first-ever cerebrovascular accident. Thirty-two patients were randomized to receive modified constraint-induced movement therapy (restraint of the unaffected limb combined with intensive training of the affected limb) or traditional rehabilitation for three weeks. Kinematic analysis was used to assess motor control characteristics as patients reached to grasp a beverage can. Functional outcomes were evaluated using the Motor Activity Log and Functional Independence Measure. There were moderate and significant effects of modified constraint-induced movement therapy on some aspects of motor control of reach-to-grasp and on functional ability. The modified constraint-induced movement therapy group preplanned reaching and grasping (P=0.018) more efficiently and depended more on the feedforward control of reaching (P=0.046) than did the traditional rehabilitation group. The modified constraint-induced movement therapy group also showed significantly improved functional performance on the Motor Activity Log (Pcontrol strategy during goal-directed reaching, a possible mechanism for the improved movement performance of stroke patients undergoing this therapy.

A self-centering active probing technique for kinematic parameter identification and verification of articulated arm coordinate measuring machines

International Nuclear Information System (INIS)

Santolaria, J; Brau, A; Velázquez, J; Aguilar, J J

2010-01-01

A crucial task in the procedure of identifying the parameters of a kinematic model of an articulated arm coordinate measuring machine (AACMM) or robot arm is the process of capturing data. In this paper a capturing data method is analyzed using a self-centering active probe, which drastically reduces the capture time and the required number of positions of the gauge as compared to the usual standard and manufacturer methods. The mathematical models of the self-centering active probe and AACMM are explained, as well as the mathematical model that links the AACMM global reference system to the probe reference system. We present a self-calibration method that will allow us to determine a homogeneous transformation matrix that relates the probe's reference system to the AACMM last reference system from the probing of a single sphere. In addition, a comparison between a self-centering passive probe and self-centering active probe is carried out to show the advantages of the latter in the procedures of kinematic parameter identification and verification of the AACMM

Kinematic and Dynamic Simulation Analysis of Hydraulic Excavator’s Working Equipment based on ADAMS

Directory of Open Access Journals (Sweden)

Yu Hong Yan

2016-01-01

Full Text Available This paper establishes the 3D excavator model according to the actual size in UG firstly. Then based on the virtual simulation software ADAMS, the virtual prototype of the working device is built by adding interrelated constraints(kinematic pair and hydraulic cylinder driving function and load secondly. This paper gets the main parameters of the excavator working scope and the pressure situation change curves of point of each hydraulic cylinder by making kinematic and dynamic simulation analysis of hydraulic excavator’s working equipment at last. The conclusion providing design theory and improvement for the excavator’s working device, which also play an important role in improving the level of China’s excavator design, enhancing excavator’s performance and promoting the rapid development of excavator industry.

Effects of scapular taping on the activity onset of scapular muscles and the scapular kinematics in volleyball players with rotator cuff tendinopathy.

Science.gov (United States)

Leong, Hio Teng; Ng, Gabriel Yin-Fat; Fu, Siu Ngor

2017-06-01

To examine the effect of scapular taping on the activity onset of scapular muscles and the scapular kinematics during arm elevation in volleyball players with rotator cuff (RC) tendinopathy. Randomized placebo-controlled repeated measures METHODS: Twenty-six male volleyball players with RC tendinopathy (mean age=23.6±3.3years) participated in the study. Electromyography (EMG) activity onset of upper trapezius (UT), middle trapezius (MT), lower trapezius (LT) and serratus anterior (SA) and the three-dimensional scapular kinematics quantified by using an acromial marker cluster method were compared with three scapular taping protocols, namely, no taping, therapeutic taping, and placebo taping. The MT, LT and SA activated significantly earlier in both therapeutic taping (all p<0.005) and placebo taping conditions than no taping conditions (all p<0.002). There was a small increase in the scapular upward rotation when therapeutic taping and no taping conditions were compared (p=0.007). Scapular taping may enhance the neuromotor control of the scapular muscles. Whether it provides adequate support for normal scapular kinematics during arm movement in athletes with RC tendinopathy await for further studies. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Thoracolumbar spine loading associated with kinematics of the young and the elderly during activities of daily living.

Science.gov (United States)

Ignasiak, Dominika; Rüeger, Andrea; Sperr, Ramona; Ferguson, Stephen J

2018-03-21

Excessive mechanical loading of the spine is a critical factor in vertebral fracture initiation. Most vertebral fractures develop spontaneously or due to mild trauma, as physiological loads during activities of daily living might exceed the failure load of osteoporotic vertebra. Spinal loading patterns are affected by vertebral kinematics, which differ between elderly and young individuals. In this study, the effects of age-related changes in spine kinematics on thoracolumbar spinal segmental loading during dynamic activities of daily living were investigated using combined experimental and modeling approach. Forty-four healthy volunteers were recruited into two age groups: young (N = 23, age = 27.1 ± 3.8) and elderly (N = 21, age = 70.1 ± 3.9). The spinal curvature was assessed with a skin-surface device and the kinematics of the spine and lower extremities were recorded during daily living tasks (flexion-extension and stand-sit-stand) with a motion capture system. The obtained data were used as input for a musculoskeletal model with a detailed thoracolumbar spine representation. To isolate the effect of kinematics on predicted loads, other model properties were kept constant. Inverse dynamics simulations were performed in the AnyBody Modeling System to estimate corresponding spinal loads. The maximum compressive loads predicted for the elderly motion patterns were lower than those of the young for L2/L3 and L3/L4 lumbar levels during flexion and for upper thoracic levels during stand-to-sit (T1/T2-T8/T9) and sit-to-stand (T3/T4-T6/T7). However, the maximum loads predicted for the lower thoracic levels (T9/T10-L1/L2), a common site of vertebral fractures, were similar compared to the young. Nevertheless, these loads acting on the vertebrae of reduced bone quality might contribute to a higher fracture risk for the elderly. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Effects on Kinematics and Muscle Activity of Walking in a Robotic Gait Trainer During Zero-Force Control.

Science.gov (United States)

van Asseldonk, Edwin H F; Veneman, Jan F; Ekkelenkamp, Ralf; Buurke, Jaap H; van der Helm, Frans C T; van der Kooij, Herman

2008-08-01

"Assist as needed" control algorithms promote activity of patients during robotic gait training. Implementing these requires a free walking mode of a device, as unassisted motions should not be hindered. The goal of this study was to assess the normality of walking in the free walking mode of the LOPES gait trainer, an 8 degrees-of-freedom lightweight impedance controlled exoskeleton. Kinematics, gait parameters and muscle activity of walking in a free walking mode in the device were compared with those of walking freely on a treadmill. Average values and variability of the spatio-temporal gait variables showed no or small (relative to cycle-to-cycle variability) changes and the kinematics showed a significant and relevant decrease in knee angle range only. Muscles involved in push off showed a small decrease, whereas muscles involved in acceleration and deceleration of the swing leg showed an increase of their activity. Timing of the activity was mainly unaffected. Most of the observed differences could be ascribed to the inertia of the exoskeleton. Overall, walking with the LOPES resembled free walking, although this required several adaptations in muscle activity. These adaptations are such that we expect that Assist as Needed training can be implemented in LOPES.

TP-Space RRT – Kinematic Path Planning of Non-Holonomic Any-Shape Vehicles

Directory of Open Access Journals (Sweden)

Jose Luis Blanco

2015-05-01

Full Text Available The autonomous navigation of vehicles typically combines two kinds of methods: a path is first planned, and then the robot is driven by a local obstacle-avoidance controller. The present work, which focuses on path planning, proposes an extension to the well-known rapidly-exploring random tree (RRT algorithm to allow its integration with a trajectory parameter-space (TP-space as an efficient method to detect collision-free, kinematically-feasible paths for arbitrarily-shaped vehicles. In contrast to original RRT, this proposal generates navigation trees, with poses as nodes, whose edges are all kinematically-feasible paths, suitable to being accurately followed by vehicles driven by pure reactive algorithms. Initial experiments demonstrate the suitability of the method with an Ackermann-steering vehicle model whose severe kinematic constraints cannot be obviated. An important result that sets this work apart from previous research is the finding that employing several families of potential trajectories to expand the tree, which can be done efficiently under the TP-space formalism, improves the optimality of the planned trajectories. A reference C++ implementation has been released as open-source.

Fundamental Activity Constraints Lead to Specific Interpretations of the Connectome.

Directory of Open Access Journals (Sweden)

Jannis Schuecker

2017-02-01

Full Text Available The continuous integration of experimental data into coherent models of the brain is an increasing challenge of modern neuroscience. Such models provide a bridge between structure and activity, and identify the mechanisms giving rise to experimental observations. Nevertheless, structurally realistic network models of spiking neurons are necessarily underconstrained even if experimental data on brain connectivity are incorporated to the best of our knowledge. Guided by physiological observations, any model must therefore explore the parameter ranges within the uncertainty of the data. Based on simulation results alone, however, the mechanisms underlying stable and physiologically realistic activity often remain obscure. We here employ a mean-field reduction of the dynamics, which allows us to include activity constraints into the process of model construction. We shape the phase space of a multi-scale network model of the vision-related areas of macaque cortex by systematically refining its connectivity. Fundamental constraints on the activity, i.e., prohibiting quiescence and requiring global stability, prove sufficient to obtain realistic layer- and area-specific activity. Only small adaptations of the structure are required, showing that the network operates close to an instability. The procedure identifies components of the network critical to its collective dynamics and creates hypotheses for structural data and future experiments. The method can be applied to networks involving any neuron model with a known gain function.

Differences in Muscle Activation and Kinematics Between Cable-Based and Selectorized Weight Training.

Science.gov (United States)

Signorile, Joseph F; Rendos, Nicole K; Heredia Vargas, Hector H; Alipio, Taislaine C; Regis, Rebecca C; Eltoukhy, Moataz M; Nargund, Renu S; Romero, Matthew A

2017-02-01

Signorile, JF, Rendos, NK, Heredia Vargas, HH, Alipio, TC, Regis, RC, Eltoukhy, MM, Nargund, RS, and Romero, MA. Differences in muscle activation and kinematics between cable-based and selectorized weight training. J Strength Cond Res 31(2): 313-322, 2017-Cable resistance training machines are showing resurgent popularity and allow greater number of degrees of freedom than typical selectorized equipment. Given that specific kinetic chains are used during distinct activities of daily living (ADL), cable machines may provide more effective interventions for some ADL, whereas others may be best addressed using selectorized equipment. This study examined differences in activity levels (root mean square of the EMG [rmsEMG]) of 6 major muscles (pectoralis major, PM; anterior deltoid, AD; biceps brachii, BB; rectus abdominis, RA; external obliques, EO; and triceps brachii, TB) and kinematics of multiple joints between a cable and standard selectorized machines during the biceps curl, the chest press, and the overhead press performed at 1.5 seconds per contractile stage. Fifteen individuals (9 men, 6 women; mean age ± SD, 24.33 ± 4.88 years) participated. Machine order was randomized. Significant differences favoring cable training were seen for PM and AD during biceps curl; BB, AD, and EO for chest press; and BB and EO during overhead press (p ≤ 0.05). Greater starting and ending angles were seen for the elbow and shoulder joints during selectorized biceps curl, whereas hip and knee starting and ending angles were greater for cable machine during chest and overhead presses (p < 0.0001). Greater range of motion (ROM) favoring the cable machine was also evident (p < 0.0001). These results indicate that utilization patterns of selected muscles, joint angles, and ROMs can be varied because of machine application even when similar exercises are used, and therefore, these machines can be used selectively in training programs requiring specific motor or biomechanical

Gamma-ray constraints on hadronic and leptonic activities of decaying dark matter

International Nuclear Information System (INIS)

Chen, Chuan-Ren; Mandal, Sourav K.; Takahashi, Fuminobu

2010-01-01

While the excess in cosmic-ray electrons and positrons reported by PAMELA and Fermi may be explained by dark matter decaying primarily into charged leptons, this does not necessarily mean that dark matter should not have any hadronic decay modes. In order to quantify the allowed hadronic activities, we derive constraints on the decay rates of dark matter into WW, ZZ, hh, q q-bar and gg using the Fermi and HESS gamma-ray data. We also derive gamma-ray constraints on the leptonic e + e − , μ + μ − and τ + τ − final states. We find that dark matter must decay primarily into μ + μ − or τ + τ − in order to simultaneously explain the reported excess and meet all gamma-ray constraints

Comparative assessment of knee joint models used in multi-body kinematics optimisation for soft tissue artefact compensation.

Science.gov (United States)

Richard, Vincent; Cappozzo, Aurelio; Dumas, Raphaël

2017-09-06

Estimating joint kinematics from skin-marker trajectories recorded using stereophotogrammetry is complicated by soft tissue artefact (STA), an inexorable source of error. One solution is to use a bone pose estimator based on multi-body kinematics optimisation (MKO) embedding joint constraints to compensate for STA. However, there is some debate over the effectiveness of this method. The present study aimed to quantitatively assess the degree of agreement between reference (i.e., artefact-free) knee joint kinematics and the same kinematics estimated using MKO embedding six different knee joint models. The following motor tasks were assessed: level walking, hopping, cutting, running, sit-to-stand, and step-up. Reference knee kinematics was taken from pin-marker or biplane fluoroscopic data acquired concurrently with skin-marker data, made available by the respective authors. For each motor task, Bland-Altman analysis revealed that the performance of MKO varied according to the joint model used, with a wide discrepancy in results across degrees of freedom (DoFs), models and motor tasks (with a bias between -10.2° and 13.2° and between -10.2mm and 7.2mm, and with a confidence interval up to ±14.8° and ±11.1mm, for rotation and displacement, respectively). It can be concluded that, while MKO might occasionally improve kinematics estimation, as implemented to date it does not represent a reliable solution to the STA issue. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Glasgow-Maastricht foot model, evaluation of a 26 segment kinematic model of the foot.

Science.gov (United States)

Oosterwaal, Michiel; Carbes, Sylvain; Telfer, Scott; Woodburn, James; Tørholm, Søren; Al-Munajjed, Amir A; van Rhijn, Lodewijk; Meijer, Kenneth

2016-01-01

Accurately measuring of intrinsic foot kinematics using skin mounted markers is difficult, limited in part by the physical dimensions of the foot. Existing kinematic foot models solve this problem by combining multiple bones into idealized rigid segments. This study presents a novel foot model that allows the motion of the 26 bones to be individually estimated via a combination of partial joint constraints and coupling the motion of separate joints using kinematic rhythms. Segmented CT data from one healthy subject was used to create a template Glasgow-Maastricht foot model (GM-model). Following this, the template was scaled to produce subject-specific models for five additional healthy participants using a surface scan of the foot and ankle. Forty-three skin mounted markers, mainly positioned around the foot and ankle, were used to capture the stance phase of the right foot of the six healthy participants during walking. The GM-model was then applied to calculate the intrinsic foot kinematics. Distinct motion patterns where found for all joints. The variability in outcome depended on the location of the joint, with reasonable results for sagittal plane motions and poor results for transverse plane motions. The results of the GM-model were comparable with existing literature, including bone pin studies, with respect to the range of motion, motion pattern and timing of the motion in the studied joints. This novel model is the most complete kinematic model to date. Further evaluation of the model is warranted.

Mass density slope of elliptical galaxies from strong lensing and resolved stellar kinematics

Science.gov (United States)

Lyskova, N.; Churazov, E.; Naab, T.

2018-04-01

We discuss constraints on the mass density distribution (parametrized as ρ ∝ r-γ) in early-type galaxies provided by strong lensing and stellar kinematics data. The constraints come from mass measurements at two `pinch' radii. One `pinch' radius r1 = 2.2REinst is defined such that the Einstein (i.e. aperture) mass can be converted into the spherical mass almost independently of the mass-model. Another `pinch' radius r2 = Ropt is chosen so that the dynamical mass, derived from the line-of-sight velocity dispersion, is least sensitive to the anisotropy of stellar orbits. We verified the performance of this approach on a sample of simulated elliptical galaxies and on a sample of 15 SLACS lens galaxies at 0.01 ≤ z ≤ 0.35, which have already been analysed in Barnabè et al. by the self-consistent joint lensing and kinematic code. For massive simulated galaxies, the density slope γ is recovered with an accuracy of ˜13 per cent, unless r1 and r2 happen to be close to each other. For SLACS galaxies, we found good overall agreement with the results of Barnabè et al. with a sample-averaged slope γ = 2.1 ± 0.05. Although the two-pinch-radii approach has larger statistical uncertainties, it is much simpler and uses only few arithmetic operations with directly observable quantities.

Running accuracy analysis of a 3-RRR parallel kinematic machine considering the deformations of the links

Science.gov (United States)

Wang, Liping; Jiang, Yao; Li, Tiemin

2014-09-01

Parallel kinematic machines have drawn considerable attention and have been widely used in some special fields. However, high precision is still one of the challenges when they are used for advanced machine tools. One of the main reasons is that the kinematic chains of parallel kinematic machines are composed of elongated links that can easily suffer deformations, especially at high speeds and under heavy loads. A 3-RRR parallel kinematic machine is taken as a study object for investigating its accuracy with the consideration of the deformations of its links during the motion process. Based on the dynamic model constructed by the Newton-Euler method, all the inertia loads and constraint forces of the links are computed and their deformations are derived. Then the kinematic errors of the machine are derived with the consideration of the deformations of the links. Through further derivation, the accuracy of the machine is given in a simple explicit expression, which will be helpful to increase the calculating speed. The accuracy of this machine when following a selected circle path is simulated. The influences of magnitude of the maximum acceleration and external loads on the running accuracy of the machine are investigated. The results show that the external loads will deteriorate the accuracy of the machine tremendously when their direction coincides with the direction of the worst stiffness of the machine. The proposed method provides a solution for predicting the running accuracy of the parallel kinematic machines and can also be used in their design optimization as well as selection of suitable running parameters.

On potential energies and constraints in the dynamics of rigid bodies and particles

Directory of Open Access Journals (Sweden)

O'reilly Oliver M.

2002-01-01

Full Text Available A new treatment of kinematical constraints and potential energies arising in the dynamics of systems of rigid bodies and particles is presented which is suited to Newtonian and Lagrangian formulations. Its novel feature is the imposing of invariance requirements on the constraint functions and potential energy functions. These requirements are extensively used in continuum mechanics and, in the present context, one finds certain generalizations of Newton's third law of motion and an elucidation of the nature of constraint forces and moments. One motivation for such a treatment can be found by considering approaches where invariance requirements are ignored. In contrast to the treatment presented in this paper, it is shown that this may lead to a difficulty in formulating the equations governing the motion of the system.

Finite Element Method-Based Kinematics and Closed-Loop Control of Soft, Continuum Manipulators.

Science.gov (United States)

Bieze, Thor Morales; Largilliere, Frederick; Kruszewski, Alexandre; Zhang, Zhongkai; Merzouki, Rochdi; Duriez, Christian

2018-06-01

This article presents a modeling methodology and experimental validation for soft manipulators to obtain forward kinematic model (FKM) and inverse kinematic model (IKM) under quasi-static conditions (in the literature, these manipulators are usually classified as continuum robots. However, their main characteristic of interest in this article is that they create motion by deformation, as opposed to the classical use of articulations). It offers a way to obtain the kinematic characteristics of this type of soft robots that is suitable for offline path planning and position control. The modeling methodology presented relies on continuum mechanics, which does not provide analytic solutions in the general case. Our approach proposes a real-time numerical integration strategy based on finite element method with a numerical optimization based on Lagrange multipliers to obtain FKM and IKM. To reduce the dimension of the problem, at each step, a projection of the model to the constraint space (gathering actuators, sensors, and end-effector) is performed to obtain the smallest number possible of mathematical equations to be solved. This methodology is applied to obtain the kinematics of two different manipulators with complex structural geometry. An experimental comparison is also performed in one of the robots, between two other geometric approaches and the approach that is showcased in this article. A closed-loop controller based on a state estimator is proposed. The controller is experimentally validated and its robustness is evaluated using Lypunov stability method.

A DOUBLE-RING ALGORITHM FOR MODELING SOLAR ACTIVE REGIONS: UNIFYING KINEMATIC DYNAMO MODELS AND SURFACE FLUX-TRANSPORT SIMULATIONS

International Nuclear Information System (INIS)

Munoz-Jaramillo, Andres; Martens, Petrus C. H.; Nandy, Dibyendu; Yeates, Anthony R.

2010-01-01

The emergence of tilted bipolar active regions (ARs) and the dispersal of their flux, mediated via processes such as diffusion, differential rotation, and meridional circulation, is believed to be responsible for the reversal of the Sun's polar field. This process (commonly known as the Babcock-Leighton mechanism) is usually modeled as a near-surface, spatially distributed α-effect in kinematic mean-field dynamo models. However, this formulation leads to a relationship between polar field strength and meridional flow speed which is opposite to that suggested by physical insight and predicted by surface flux-transport simulations. With this in mind, we present an improved double-ring algorithm for modeling the Babcock-Leighton mechanism based on AR eruption, within the framework of an axisymmetric dynamo model. Using surface flux-transport simulations, we first show that an axisymmetric formulation-which is usually invoked in kinematic dynamo models-can reasonably approximate the surface flux dynamics. Finally, we demonstrate that our treatment of the Babcock-Leighton mechanism through double-ring eruption leads to an inverse relationship between polar field strength and meridional flow speed as expected, reconciling the discrepancy between surface flux-transport simulations and kinematic dynamo models.

Global sensitivity analysis of the joint kinematics during gait to the parameters of a lower limb multi-body model.

Science.gov (United States)

El Habachi, Aimad; Moissenet, Florent; Duprey, Sonia; Cheze, Laurence; Dumas, Raphaël

2015-07-01

Sensitivity analysis is a typical part of biomechanical models evaluation. For lower limb multi-body models, sensitivity analyses have been mainly performed on musculoskeletal parameters, more rarely on the parameters of the joint models. This study deals with a global sensitivity analysis achieved on a lower limb multi-body model that introduces anatomical constraints at the ankle, tibiofemoral, and patellofemoral joints. The aim of the study was to take into account the uncertainty of parameters (e.g. 2.5 cm on the positions of the skin markers embedded in the segments, 5° on the orientation of hinge axis, 2.5 mm on the origin and insertion of ligaments) using statistical distributions and propagate it through a multi-body optimisation method used for the computation of joint kinematics from skin markers during gait. This will allow us to identify the most influential parameters on the minimum of the objective function of the multi-body optimisation (i.e. the sum of the squared distances between measured and model-determined skin marker positions) and on the joint angles and displacements. To quantify this influence, a Fourier-based algorithm of global sensitivity analysis coupled with a Latin hypercube sampling is used. This sensitivity analysis shows that some parameters of the motor constraints, that is to say the distances between measured and model-determined skin marker positions, and the kinematic constraints are highly influencing the joint kinematics obtained from the lower limb multi-body model, for example, positions of the skin markers embedded in the shank and pelvis, parameters of the patellofemoral hinge axis, and parameters of the ankle and tibiofemoral ligaments. The resulting standard deviations on the joint angles and displacements reach 36° and 12 mm. Therefore, personalisation, customisation or identification of these most sensitive parameters of the lower limb multi-body models may be considered as essential.

Overground-Propulsion Kinematics and Acceleration in Elite Wheelchair Rugby.

Science.gov (United States)

Haydon, David S; Pinder, Ross A; Grimshaw, Paul N; Robertson, William S P

2018-02-01

Maximal acceleration from standstill has been identified as a key performance indicator in wheelchair rugby; however, the impact of classification and kinematic variables on performance has received limited attention. This study aimed to investigate kinematic variables during maximal acceleration, with level of activity limitation accounted for using sport-classification scores. Based on their sporting classification scores, which reflect combined trunk, arm, and hand function, 25 elite wheelchair rugby players were analyzed in high-, mid-, and low-point groups before completing five 5-m sprints from a stationary position. Inertial measurement units and video analysis were used to monitor key kinematic variables. Significant differences in kinematic variables were evident across the classification groups, particularly for the first stroke-contact angle (1-way ANOVA F 2,122  = 51.5, P propulsion approaches exist across classification groups, with this information potentially informing individual wheelchair setups and training programs.

Effects of Stroke on Ipsilesional End-Effector Kinematics in a Multi-Step Activity of Daily Living

OpenAIRE

Gulde, Philipp; Hughes, Charmayne Mary Lee; Hermsdörfer, Joachim

2017-01-01

Background: Stroke frequently impairs activities of daily living (ADL) and deteriorates the function of the contra- as well as the ipsilesional limbs. In order to analyze alterations of higher motor control unaffected by paresis or sensory loss, the kinematics of ipsilesional upper limb movements in patients with stroke has previously been analyzed during prehensile movements and simple tool use actions. By contrast, motion recording of multi-step ADL is rare and patient-control comparisons f...

Shaping tissues by balancing active forces and geometric constraints

Science.gov (United States)

Foolen, Jasper; Yamashita, Tadahiro; Kollmannsberger, Philip

2016-02-01

The self-organization of cells into complex tissues during growth and regeneration is a combination of physical-mechanical events and biochemical signal processing. Cells actively generate forces at all stages in this process, and according to the laws of mechanics, these forces result in stress fields defined by the geometric boundary conditions of the cell and tissue. The unique ability of cells to translate such force patterns into biochemical information and vice versa sets biological tissues apart from any other material. In this topical review, we summarize the current knowledge and open questions of how forces and geometry act together on scales from the single cell to tissues and organisms, and how their interaction determines biological shape and structure. Starting with a planar surface as the simplest type of geometric constraint, we review literature on how forces during cell spreading and adhesion together with geometric constraints impact cell shape, stress patterns, and the resulting biological response. We then move on to include cell-cell interactions and the role of forces in monolayers and in collective cell migration, and introduce curvature at the transition from flat cell sheets to three-dimensional (3D) tissues. Fibrous 3D environments, as cells experience them in the body, introduce new mechanical boundary conditions and change cell behaviour compared to flat surfaces. Starting from early work on force transmission and collagen remodelling, we discuss recent discoveries on the interaction with geometric constraints and the resulting structure formation and network organization in 3D. Recent literature on two physiological scenarios—embryonic development and bone—is reviewed to demonstrate the role of the force-geometry balance in living organisms. Furthermore, the role of mechanics in pathological scenarios such as cancer is discussed. We conclude by highlighting common physical principles guiding cell mechanics, tissue patterning and

Shaping tissues by balancing active forces and geometric constraints

International Nuclear Information System (INIS)

Foolen, Jasper; Yamashita, Tadahiro; Kollmannsberger, Philip

2016-01-01

The self-organization of cells into complex tissues during growth and regeneration is a combination of physical–mechanical events and biochemical signal processing. Cells actively generate forces at all stages in this process, and according to the laws of mechanics, these forces result in stress fields defined by the geometric boundary conditions of the cell and tissue. The unique ability of cells to translate such force patterns into biochemical information and vice versa sets biological tissues apart from any other material. In this topical review, we summarize the current knowledge and open questions of how forces and geometry act together on scales from the single cell to tissues and organisms, and how their interaction determines biological shape and structure. Starting with a planar surface as the simplest type of geometric constraint, we review literature on how forces during cell spreading and adhesion together with geometric constraints impact cell shape, stress patterns, and the resulting biological response. We then move on to include cell–cell interactions and the role of forces in monolayers and in collective cell migration, and introduce curvature at the transition from flat cell sheets to three-dimensional (3D) tissues. Fibrous 3D environments, as cells experience them in the body, introduce new mechanical boundary conditions and change cell behaviour compared to flat surfaces. Starting from early work on force transmission and collagen remodelling, we discuss recent discoveries on the interaction with geometric constraints and the resulting structure formation and network organization in 3D. Recent literature on two physiological scenarios—embryonic development and bone—is reviewed to demonstrate the role of the force-geometry balance in living organisms. Furthermore, the role of mechanics in pathological scenarios such as cancer is discussed. We conclude by highlighting common physical principles guiding cell mechanics, tissue patterning

A Subject-Specific Kinematic Model to Predict Human Motion in Exoskeleton-Assisted Gait

Science.gov (United States)

Torricelli, Diego; Cortés, Camilo; Lete, Nerea; Bertelsen, Álvaro; Gonzalez-Vargas, Jose E.; del-Ama, Antonio J.; Dimbwadyo, Iris; Moreno, Juan C.; Florez, Julian; Pons, Jose L.

2018-01-01

The relative motion between human and exoskeleton is a crucial factor that has remarkable consequences on the efficiency, reliability and safety of human-robot interaction. Unfortunately, its quantitative assessment has been largely overlooked in the literature. Here, we present a methodology that allows predicting the motion of the human joints from the knowledge of the angular motion of the exoskeleton frame. Our method combines a subject-specific skeletal model with a kinematic model of a lower limb exoskeleton (H2, Technaid), imposing specific kinematic constraints between them. To calibrate the model and validate its ability to predict the relative motion in a subject-specific way, we performed experiments on seven healthy subjects during treadmill walking tasks. We demonstrate a prediction accuracy lower than 3.5° globally, and around 1.5° at the hip level, which represent an improvement up to 66% compared to the traditional approach assuming no relative motion between the user and the exoskeleton. PMID:29755336

A Subject-Specific Kinematic Model to Predict Human Motion in Exoskeleton-Assisted Gait.

Science.gov (United States)

Torricelli, Diego; Cortés, Camilo; Lete, Nerea; Bertelsen, Álvaro; Gonzalez-Vargas, Jose E; Del-Ama, Antonio J; Dimbwadyo, Iris; Moreno, Juan C; Florez, Julian; Pons, Jose L

2018-01-01

The relative motion between human and exoskeleton is a crucial factor that has remarkable consequences on the efficiency, reliability and safety of human-robot interaction. Unfortunately, its quantitative assessment has been largely overlooked in the literature. Here, we present a methodology that allows predicting the motion of the human joints from the knowledge of the angular motion of the exoskeleton frame. Our method combines a subject-specific skeletal model with a kinematic model of a lower limb exoskeleton (H2, Technaid), imposing specific kinematic constraints between them. To calibrate the model and validate its ability to predict the relative motion in a subject-specific way, we performed experiments on seven healthy subjects during treadmill walking tasks. We demonstrate a prediction accuracy lower than 3.5° globally, and around 1.5° at the hip level, which represent an improvement up to 66% compared to the traditional approach assuming no relative motion between the user and the exoskeleton.

Distance and slope constraints: adaptation and variability in golf putting.

Science.gov (United States)

Dias, Gonçalo; Couceiro, Micael S; Barreiros, João; Clemente, Filipe M; Mendes, Rui; Martins, Fernando M

2014-07-01

The main objective of this study is to understand the adaptation to external constraints and the effects of variability in a golf putting task. We describe the adaptation of relevant variables of golf putting to the distance to the hole and to the addition of a slope. The sample consisted of 10 adult male (33.80 ± 11.89 years), volunteers, right handed and highly skilled golfers with an average handicap of 10.82. Each player performed 30 putts at distances of 2, 3 and 4 meters (90 trials in Condition 1). The participants also performed 90 trials, at the same distances, with a constraint imposed by a slope (Condition 2). The results indicate that the players change some parameters to adjust to the task constraints, namely the duration of the backswing phase, the speed of the club head and the acceleration at the moment of impact with the ball. The effects of different golf putting distances in the no-slope condition on different kinematic variables suggest a linear adjustment to distance variation that was not observed when in the slope condition.

Nuclear reaction studies using inverse kinematics

International Nuclear Information System (INIS)

Shapira, D.

1985-01-01

Reaction studies with reversed kinematics refer to studies of nuclear reactions induced by a heavy projectile colliding with lighter target nuclei. The technique of using reversed kinematics is costly in terms of the available center-of-mass energy. Most of the projectile's energy goes into forward motion of the reaction products in the laboratory system. Examples are presented where the use of reversed kinematics techniques has provided new information on certain reaction processes. A list of kinematic properties and advantages they may afford is shown. Clearly the possible studies listed can be done without using reversed kinematics but because of the difficulty associated with some of these studies they were never performed until more energetic heavier beams have become available and the reversed kinematics technique was utilized

Aging and rejuvenation of active matter under topological constraints.

Science.gov (United States)

Janssen, Liesbeth M C; Kaiser, Andreas; Löwen, Hartmut

2017-07-18

The coupling of active, self-motile particles to topological constraints can give rise to novel non-equilibrium dynamical patterns that lack any passive counterpart. Here we study the behavior of self-propelled rods confined to a compact spherical manifold by means of Brownian dynamics simulations. We establish the state diagram and find that short active rods at sufficiently high density exhibit a glass transition toward a disordered state characterized by persistent self-spinning motion. By periodically melting and revitrifying the spherical spinning glass, we observe clear signatures of time-dependent aging and rejuvenation physics. We quantify the crucial role of activity in these non-equilibrium processes, and rationalize the aging dynamics in terms of an absorbing-state transition toward a more stable active glassy state. Our results demonstrate both how concepts of passive glass phenomenology can carry over into the realm of active matter, and how topology can enrich the collective spatiotemporal dynamics in inherently non-equilibrium systems.

Effects of thigh holster use on kinematics and kinetics of active duty police officers

OpenAIRE

Larsen, Louise B.; Tranberg, Roy; Ramstrand, Nerrolyn

2016-01-01

Background: Body armour, duty belts and belt mounted holsters are standard equipment used by the Swedish police and have been shown to affect performance of police specific tasks, to decrease mobility and to potentially influence back pain. This study aimed to investigate the effects on gait kinematics and kinetics associated with use of an alternate load carriage system incorporating a thigh holster. Methods: Kinematic, kinetic and temporospatial data were collected using three dimensional g...

Detumbling control for kinematically redundant space manipulator post-grasping a rotational satellite

Science.gov (United States)

Wang, Mingming; Luo, Jianjun; Yuan, Jianping; Walter, Ulrich

2017-12-01

The objective of this paper is to establish a detumbling strategy and a coordination control scheme for a kinematically redundant space manipulator post-grasping a rotational satellite. First, the dynamics of the kinematically redundant space robot after grasping the target is presented, which lays the foundation for the coordination controller design. Subsequently, optimal detumbling and motion planning strategy for the post-capture phase is proposed based on the quartic Bézier curves and adaptive differential evolution (DE) algorithm subject to the specific constraints. Both detumbling time and control torques are taken into account for the generation of the optimal detumbling strategy. Furthermore, a coordination control scheme is presented to track the designed reference path while regulating the attitude of the chaser to a desired value, which successfully dumps the initial angular velocity of the rotational satellite and controls the base attitude synchronously. Simulation results are presented for detumbling a target with rotational motion using a 7 degree-of-freedom (DOF) redundant space manipulator, which demonstrates the effectiveness of the proposed method.

A kinematic comparison of successful and unsuccessful tennis serves across the elite development pathway.

Science.gov (United States)

Whiteside, David; Elliott, Bruce; Lay, Brendan; Reid, Machar

2013-08-01

While velocity generation is an obvious prerequisite to proficient tennis serve performance, it is also the only stroke where players are obliged to negotiate a unique target constraint. Therefore, the dearth of research attending to the accuracy component of the serve is surprising. This study compared the body, racquet and ball kinematics characterising successful serves and service faults, missed into the net, in two groups of elite junior female players and one professional female tennis player. Three-dimensional body, racquet and ball kinematics were recorded using a 22-camera VICON motion analysis system. There were no differences in body kinematics between successful serves and service faults, suggesting that service faults cannot be attributed to a single source of biomechanical error. However, service faults missing into the net are characterized by projection angles significantly further below the horizontal, implying that consistency in this end-point parameter is critical to successful performance. Regulation of this parameter appears dependent on compensatory adjustments in the distal elbow and wrist joints immediately prior to impact and also perceptual feedback. Accordingly, coordination of the distal degrees of freedom and a refined perception-action coupling appear more important to success than any isolated mechanical component of the service action. Copyright © 2013 Elsevier B.V. All rights reserved.

Kinematic modeling of a 7-degree of freedom spatial hybrid manipulator for medical surgery.

Science.gov (United States)

Singh, Amanpreet; Singla, Ekta; Soni, Sanjeev; Singla, Ashish

2018-01-01

The prime objective of this work is to deal with the kinematics of spatial hybrid manipulators. In this direction, in 1955, Denavit and Hartenberg proposed a consistent and concise method, known as D-H parameters method, to deal with kinematics of open serial chains. From literature review, it is found that D-H parameter method is widely used to model manipulators consisting of lower pairs. However, the method leads to ambiguities when applied to closed-loop, tree-like and hybrid manipulators. Furthermore, in the dearth of any direct method to model closed-loop, tree-like and hybrid manipulators, revisions of this method have been proposed from time-to-time by different researchers. One such kind of revision using the concept of dummy frames has successfully been proposed and implemented by the authors on spatial hybrid manipulators. In that work, authors have addressed the orientational inconsistency of the D-H parameter method, restricted to body-attached frames only. In the current work, the condition of body-attached frames is relaxed and spatial frame attachment is considered to derive the kinematic model of a 7-degree of freedom spatial hybrid robotic arm, along with the development of closed-loop constraints. The validation of the new kinematic model has been performed with the help of a prototype of this 7-degree of freedom arm, which is being developed at Council of Scientific & Industrial Research-Central Scientific Instruments Organisation Chandigarh to aid the surgeon during a medical surgical task. Furthermore, the developed kinematic model is used to develop the first column of the Jacobian matrix, which helps in providing the estimate of the tip velocity of the 7-degree of freedom manipulator when the first joint velocity is known.

Directed Neutron Beams From Inverse Kinematic Reactions

Science.gov (United States)

Vanhoy, J. R.; Guardala, N. A.; Glass, G. A.

2011-06-01

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.

Physical activity and senior games participation: benefits, constraints, and behaviors.

Science.gov (United States)

Cardenas, David; Henderson, Karla A; Wilson, Beth E

2009-04-01

The purpose of the article was to examine the physical activity perceptions and behaviors of older adults who were active participants in a statewide senior games (i.e., North Carolina Senior Games; NCSG) program with its focus on year-round involvement through activities in local communities. A random sample of 440 older adults (55 years and older) completed a questionnaire in 2006 about their participation in community-based senior games. A uniqueness of this study is its focus on active older adults, which provides insight into how to maintain physical involvement. Older adults who were most active perceived the most benefits from senior games but did not necessarily have the fewest constraints. This study of NCSG as an organization designed to promote healthy living in communities offered an example of how a social-ecological framework aimed at health promotion can be applied.

Analysis of a closed-kinematic chain robot manipulator

Science.gov (United States)

Nguyen, Charles C.; Pooran, Farhad J.

1988-01-01

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

Knee and Hip Joint Kinematics Predict Quadriceps and Hamstrings Neuromuscular Activation Patterns in Drop Jump Landings.

Directory of Open Access Journals (Sweden)

Bart Malfait

Full Text Available The purpose was to assess if variation in sagittal plane landing kinematics is associated with variation in neuromuscular activation patterns of the quadriceps-hamstrings muscle groups during drop vertical jumps (DVJ.Fifty female athletes performed three DVJ. The relationship between peak knee and hip flexion angles and the amplitude of four EMG vectors was investigated with trajectory-level canonical correlation analyses over the entire time period of the landing phase. EMG vectors consisted of the {vastus medialis(VM,vastus lateralis(VL}, {vastus medialis(VM,hamstring medialis(HM}, {hamstring medialis(HM,hamstring lateralis(HL} and the {vastus lateralis(VL,hamstring lateralis(HL}. To estimate the contribution of each individual muscle, linear regressions were also conducted using one-dimensional statistical parametric mapping.The peak knee flexion angle was significantly positively associated with the amplitudes of the {VM,HM} and {HM,HL} during the preparatory and initial contact phase and with the {VL,HL} vector during the peak loading phase (p<0.05. Small peak knee flexion angles were significantly associated with higher HM amplitudes during the preparatory and initial contact phase (p<0.001. The amplitudes of the {VM,VL} and {VL,HL} were significantly positively associated with the peak hip flexion angle during the peak loading phase (p<0.05. Small peak hip flexion angles were significantly associated with higher VL amplitudes during the peak loading phase (p = 0.001. Higher external knee abduction and flexion moments were found in participants landing with less flexed knee and hip joints (p<0.001.This study demonstrated clear associations between neuromuscular activation patterns and landing kinematics in the sagittal plane during specific parts of the landing. These findings have indicated that an erect landing pattern, characterized by less hip and knee flexion, was significantly associated with an increased medial and posterior

Inverse Kinematics using Quaternions

DEFF Research Database (Denmark)

Henriksen, Knud; Erleben, Kenny; Engell-Nørregård, Morten

In this project I describe the status of inverse kinematics research, with the focus firmly on the methods that solve the core problem. An overview of the different methods are presented Three common methods used in inverse kinematics computation have been chosen as subject for closer inspection....

Galaxy masses in large surveys: Connecting luminous and dark matter with weak lensing and kinematics

Science.gov (United States)

Reyes, Reinabelle

2011-01-01

Galaxy masses are difficult to determine because light traces stars and gas in a non-trivial way, and does not trace dark matter, which extends well beyond the luminous regions of galaxies. In this thesis, I use the most direct probes of dark matter available---weak gravitational lensing and galaxy kinematics---to trace the total mass in galaxies (and galaxy clusters) in large surveys. In particular, I use the large, homogeneous dataset from the Sloan Digital Sky Survey (SDSS), which provides spectroscopic redshifts for a large sample of galaxies at z ≲ 0.2 and imaging data to a depth of r < 22. By combining complementary probes, I am able to obtain robust observational constraints that cannot be obtained from any single technique alone. First, I use weak lensing of galaxy clusters to derive an optimal optical tracer of cluster mass, which was found to be a combination of cluster richness and the luminosity of the brightest cluster galaxy. Next, I combine weak lensing of luminous red galaxies with redshift distortions and clustering measurements to derive a robust probe of gravity on cosmological scales. Finally, I combine weak lensing with the kinematics of disk galaxies to constrain the total mass profile over several orders of magnitude. I derive a minimal-scatter relation between disk velocity and stellar mass (also known as the Tully-Fisher relation) that can be used, by construction, on a similarly-selected lens sample. Then, I combine this relation with halo mass measurements from weak lensing to place constraints on the ratio of the optical to virial velocities, as well as the ratio of halo to stellar masses, both as a function of stellar mass. These results will serve as inputs to and constraints on disk galaxy formation models, which will be explored in future work.

A Kinematic Link Between Boxy Bulges, Stellar Bars, and Nuclear Activity in NGC 3079 and NGC 4388

Science.gov (United States)

Veilleux, S.; Bland-Hawthrorn, J.; Cecil, Gerald

1999-01-01

We present direct kinematic evidence for bar streaming in two active galaxies with boxy stellar bulges. The Hawaii Imaging Fabry-Perot Interferometer was used on the Canada-France-Hawaii 3.6-m telescope and the University of Hawaii 2.2-m telescope to derive the two-dimensional velocity field of the line-emitting gas in the disks of the Sc galaxy NGC 3079 and the Sb galaxy NGC 4388. In contrast to previous work based on long-slit data, the detection of the bar potential from the Fabry-Perot data does not rely on the existence of inner Lindblad resonances or strong bar-induced shocks. Simple kinematic models which approximate the intrinsic gas orbits as nonintersecting, inclined elliptical annuli that conserve angular momentum characterize the observed velocity fields. In NGC 3079, bar streaming motions with moderately eccentric orbits (e = b/a approx. 0.7) aligned along PA = 130 deg. intrinsic to the disk (PA = 97 deg. on the sky) are detected out to R(sub b) = 3.6 kpc. The orbits become increasingly circular beyond that radius (e = 1 at R(sub d) approx. = 6 kpc). The best model for NGC 4388 includes highly eccentric orbits (e approx. 0.3) for R(sub) less than or equal to 1.5 kpc which are aligned along PA = 135 deg. intrinsic to the disk (PA = 100 deg. on the sky). The observed "spiral arms" are produced by having the orbits become increasingly circular from the ends of the bar to the edge of the disk (R(sub d) approx. = 5 kpc), and the intrinsic bar PA shifting from 135 deg. to 90 deg.. Box-shaped bulges in both NGC 3079 and NGC 4388 are confirmed using new near-infrared images to reduce dust obscuration. Morphological analysis of starlight in these galaxies is combined with the gas kinematics derived from the Fabry-Perot spectra to test evolutionary models of stellar bars that involve transitory boxy bulges, and to quantify the importance of such bars in fueling active nuclei. Our data support the evolutionary bar models, but fail to prove convincingly that the

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

Science.gov (United States)

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

2013-12-01

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

Analysis of differences in exercise recognition by constraints on physical activity of hospitalized cancer patients based on their medical history.

Science.gov (United States)

Choi, Mi-Ri; Jeon, Sang-Wan; Yi, Eun-Surk

2018-04-01

The purpose of this study is to analyze the differences among the hospitalized cancer patients on their perception of exercise and physical activity constraints based on their medical history. The study used questionnaire survey as measurement tool for 194 cancer patients (male or female, aged 20 or older) living in Seoul metropolitan area (Seoul, Gyeonggi, Incheon). The collected data were analyzed using frequency analysis, exploratory factor analysis, reliability analysis t -test, and one-way distribution using statistical program SPSS 18.0. The following results were obtained. First, there was no statistically significant difference between cancer stage and exercise recognition/physical activity constraint. Second, there was a significant difference between cancer stage and sociocultural constraint/facility constraint/program constraint. Third, there was a significant difference between cancer operation history and physical/socio-cultural/facility/program constraint. Fourth, there was a significant difference between cancer operation history and negative perception/facility/program constraint. Fifth, there was a significant difference between ancillary cancer treatment method and negative perception/facility/program constraint. Sixth, there was a significant difference between hospitalization period and positive perception/negative perception/physical constraint/cognitive constraint. In conclusion, this study will provide information necessary to create patient-centered healthcare service system by analyzing exercise recognition of hospitalized cancer patients based on their medical history and to investigate the constraint factors that prevents patients from actually making efforts to exercise.

Conceptual design and kinematic analysis of a novel parallel robot for high-speed pick-and-place operations

Science.gov (United States)

Meng, Qizhi; Xie, Fugui; Liu, Xin-Jun

2018-06-01

This paper deals with the conceptual design, kinematic analysis and workspace identification of a novel four degrees-of-freedom (DOFs) high-speed spatial parallel robot for pick-and-place operations. The proposed spatial parallel robot consists of a base, four arms and a 1½ mobile platform. The mobile platform is a major innovation that avoids output singularity and offers the advantages of both single and double platforms. To investigate the characteristics of the robot's DOFs, a line graph method based on Grassmann line geometry is adopted in mobility analysis. In addition, the inverse kinematics is derived, and the constraint conditions to identify the correct solution are also provided. On the basis of the proposed concept, the workspace of the robot is identified using a set of presupposed parameters by taking input and output transmission index as the performance evaluation criteria.

Advances in robot kinematics

CERN Document Server

Khatib, Oussama

2014-01-01

The topics addressed in this book cover the whole range of kinematic analysis, synthesis and design and consider robotic systems possessing serial, parallel and cable driven mechanisms. The robotic systems range from being less than fully mobile to kinematically redundant to overconstrained.  The fifty-six contributions report the latest results in robot kinematics with emphasis on emerging areas such as design and control of humanoids or humanoid subsystems. The book is of interest to researchers wanting to bring their knowledge up to date regarding modern topics in one of the basic disciplines in robotics, which relates to the essential property of robots, the motion of mechanisms.

Postural Hand Synergies during Environmental Constraint Exploitation

Directory of Open Access Journals (Sweden)

Cosimo Della Santina

2017-08-01

Full Text Available Humans are able to intuitively exploit the shape of an object and environmental constraints to achieve stable grasps and perform dexterous manipulations. In doing that, a vast range of kinematic strategies can be observed. However, in this work we formulate the hypothesis that such ability can be described in terms of a synergistic behavior in the generation of hand postures, i.e., using a reduced set of commonly used kinematic patterns. This is in analogy with previous studies showing the presence of such behavior in different tasks, such as grasping. We investigated this hypothesis in experiments performed by six subjects, who were asked to grasp objects from a flat surface. We quantitatively characterized hand posture behavior from a kinematic perspective, i.e., the hand joint angles, in both pre-shaping and during the interaction with the environment. To determine the role of tactile feedback, we repeated the same experiments but with subjects wearing a rigid shell on the fingertips to reduce cutaneous afferent inputs. Results show the persistence of at least two postural synergies in all the considered experimental conditions and phases. Tactile impairment does not alter significantly the first two synergies, and contact with the environment generates a change only for higher order Principal Components. A good match also arises between the first synergy found in our analysis and the first synergy of grasping as quantified by previous work. The present study is motivated by the interest of learning from the human example, extracting lessons that can be applied in robot design and control. Thus, we conclude with a discussion on implications for robotics of our findings.

The effect of lift teams on kinematics and muscle activity of the upper extremity and trunk in bricklayers.

Science.gov (United States)

Anton, Dan; Mizner, Ryan L; Hess, Jennifer A

2013-04-01

Workplace-simulation study using a crossover design. To evaluate the effect of lift teams on trunk and upper extremity kinematics and muscle activity among bricklayers. Healthcare practitioners often instruct individuals with work-related musculoskeletal disorders in proper lifting techniques. Bricklayers are especially affected by lifting-related musculoskeletal disorders. Lift teams are a possible intervention for reducing exposure to heavy lifting. Eighteen apprentice bricklayers constructed walls with concrete blocks alone (1 person) and in 2-person lift teams. Peak shoulder and trunk kinematics and normalized mean surface electromyography of the upper trapezius, lumbar paraspinals, and flexor forearm muscles were collected bilaterally. Differences between construction methods and rows 1, 3, and 6 of the wall were calculated with repeated-measures analyses of variance. Working in lift teams required less trunk flexion (P = .008) at row 1 but more sidebending at row 6 (Pteam workers. Lift-team peak shoulder flexion was lower at row 3 (P = .002), whereas abduction was higher at rows 1 (P = .007) and 6 (Pteams at row 6 (Pteams at all rows (P≤.002). Working in lift teams may be a beneficial intervention for reducing trunk flexion and lumbar paraspinal activity when bricklayers work at heights between the knees and waist, but lift teams are not recommended at higher working heights.

Kinematic parameters of signed verbs.

Science.gov (United States)

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

2013-10-01

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 & Wilbur, 2012a) and process these distinctions as part of the phonological structure of these verb classes in comprehension ( Malaia, Ranaweera, Wilbur, & Talavage, 2012). These studies are driven by the event visibility hypothesis by Wilbur (2003), who proposed that such use of kinematic features should be universal to sign language (SL) by the grammaticalization of physics and geometry for linguistic purposes. In a prior motion capture study, Malaia and Wilbur (2012a) lent support for the event visibility hypothesis in ASL, but there has not been quantitative data from other SLs to test the generalization to other languages. The authors investigated the kinematic parameters of predicates in Croatian Sign Language ( Hrvatskom Znakovnom Jeziku [HZJ]). Kinematic features of verb signs were affected both by event structure of the predicate (semantics) and phrase position within the sentence (prosody). The data demonstrate that kinematic features of motion in HZJ verb signs are recruited to convey morphological and prosodic information. This is the first crosslinguistic motion capture confirmation that specific kinematic properties of articulator motion are grammaticalized in other SLs to express linguistic features.

Amount of kinematic feedback affects learning of speech motor skills.

Science.gov (United States)

Ballard, Kirrie J; Smith, Heather D; Paramatmuni, Divija; McCabe, Patricia; Theodoros, Deborah G; Murdoch, Bruce E

2012-01-01

Knowledge of Performance (KP) feedback, such as biofeedback or kinematic feedback, is used to provide information on the nature and quality of movement responses for the purpose of guiding active learning or rehabilitation of motor skills. It has been proposed that KP feedback may interfere with long-term learning when provided throughout training. Here, twelve healthy English-speaking adults were trained to produce a trilled Russian [r] in words with KP kinematic feedback using electropalatography (EPG) and without KP (noKP). Five one-hour training sessions were provided over one week with testing pretraining and one day and one week posttraining. No group differences were found at pretraining or one day post training for production accuracy. A group by time interaction supported the hypothesis that providing kinematic feedback continually during skill acquisition interferes with retention.

Knee joint kinematics and kinetics during the hop and cut after soft tissue artifact suppression: Time to reconsider ACL injury mechanisms?

Science.gov (United States)

Smale, Kenneth B; Potvin, Brigitte M; Shourijeh, Mohammad S; Benoit, Daniel L

2017-09-06

The recent development of a soft tissue artifact (STA) suppression method allows us to re-evaluate the tibiofemoral kinematics currently linked to non-contact knee injuries. The purpose of this study was therefore to evaluate knee joint kinematics and kinetics in six degrees of freedom (DoF) during the loading phases of a jump lunge and side cut using this in silico method. Thirty-five healthy adults completed these movements and their surface marker trajectories were then scaled and processed with OpenSim's inverse kinematics (IK) and inverse dynamics tools. Knee flexion angle-dependent kinematic constraints defined based on previous bone pin (BP) marker trajectories were then applied to the OpenSim model during IK and these constrained results were then processed with the standard inverse dynamics tool. Significant differences for all hip, knee, and ankle DoF were observed after STA suppression for both the jump lunge and side cut. Using clinically relevant effect size estimates, we conclude that STA contamination had led to misclassifications in hip transverse plane angles, knee frontal and transverse plane angles, medial/lateral and distractive/compressive knee translations, and knee frontal plane moments between the NoBP and the BP IK solutions. Our results have substantial clinical implications since past research has used joint kinematics and kinetics contaminated by STA to identify risk factors for musculoskeletal injuries. Copyright © 2017 Elsevier Ltd. All rights reserved.

What occupant kinematics and neuromuscular responses tell us about whiplash injury.

Science.gov (United States)

Siegmund, Gunter P

2011-12-01

Literature-based review. To review the published data on occupant kinematic and neuromuscular responses during low-speed impacts and analyze how these data inform our understanding of whiplash injury. A stereotypical kinematic and neuromuscular response has been observed in human subjects exposed to rear-end impacts. Combined with various models of injury, these response data have been used to develop anti-whiplash seats that prevent whiplash injury in many, but not all, individuals exposed to a rear-end crash. Synthesis of the literature. Understanding of the occupant kinematics and neuromuscular responses, combined with data from various seat-related interventions, have shown that differential motion between the superior and inferior ends of the cervical spine is responsible for many whiplash injuries. The number of whiplash injuries not prevented by current anti-whiplash seats suggests than further work remains, possibly related to designing seats that respond dynamically to the occupant and collision properties. Neck muscles alter the head and neck kinematics during the interval in which injury likely occurs, even in initially relaxed occupants. It remains unclear whether muscle activation mitigates or exacerbates whiplash injury. If muscle activation mitigates injury, then advance warning could be used to help occupant tense their muscles before impact. Alternatively, if muscle activation exacerbates whiplash injury, then a loud preimpact sound that uncouples the startle and postural components of the muscle response could reduce peak muscle activation during a whiplash exposure. Our improved understanding of whiplash injury has led to anti-whiplash seats that have prevented many whiplash injuries. Further work remains to optimize these and possibly other systems to further reduce the number of whiplash injuries.

Unified Singularity Modeling and Reconfiguration of 3rTPS Metamorphic Parallel Mechanisms with Parallel Constraint Screws

Directory of Open Access Journals (Sweden)

Yufeng Zhuang

2015-01-01

Full Text Available This paper presents a unified singularity modeling and reconfiguration analysis of variable topologies of a class of metamorphic parallel mechanisms with parallel constraint screws. The new parallel mechanisms consist of three reconfigurable rTPS limbs that have two working phases stemming from the reconfigurable Hooke (rT joint. While one phase has full mobility, the other supplies a constraint force to the platform. Based on these, the platform constraint screw systems show that the new metamorphic parallel mechanisms have four topologies by altering the limb phases with mobility change among 1R2T (one rotation with two translations, 2R2T, and 3R2T and mobility 6. Geometric conditions of the mechanism design are investigated with some special topologies illustrated considering the limb arrangement. Following this and the actuation scheme analysis, a unified Jacobian matrix is formed using screw theory to include the change between geometric constraints and actuation constraints in the topology reconfiguration. Various singular configurations are identified by analyzing screw dependency in the Jacobian matrix. The work in this paper provides basis for singularity-free workspace analysis and optimal design of the class of metamorphic parallel mechanisms with parallel constraint screws which shows simple geometric constraints with potential simple kinematics and dynamics properties.

Effects of robotically modulating kinematic variability on motor skill learning and motivation.

Science.gov (United States)

Duarte, Jaime E; Reinkensmeyer, David J

2015-04-01

It is unclear how the variability of kinematic errors experienced during motor training affects skill retention and motivation. We used force fields produced by a haptic robot to modulate the kinematic errors of 30 healthy adults during a period of practice in a virtual simulation of golf putting. On day 1, participants became relatively skilled at putting to a near and far target by first practicing without force fields. On day 2, they warmed up at the task without force fields, then practiced with force fields that either reduced or augmented their kinematic errors and were finally assessed without the force fields active. On day 3, they returned for a long-term assessment, again without force fields. A control group practiced without force fields. We quantified motor skill as the variability in impact velocity at which participants putted the ball. We quantified motivation using a self-reported, standardized scale. Only individuals who were initially less skilled benefited from training; for these people, practicing with reduced kinematic variability improved skill more than practicing in the control condition. This reduced kinematic variability also improved self-reports of competence and satisfaction. Practice with increased kinematic variability worsened these self-reports as well as enjoyment. These negative motivational effects persisted on day 3 in a way that was uncorrelated with actual skill. In summary, robotically reducing kinematic errors in a golf putting training session improved putting skill more for less skilled putters. Robotically increasing kinematic errors had no performance effect, but decreased motivation in a persistent way. Copyright © 2015 the American Physiological Society.

Comparative shoulder kinematics during free standing, standing depression lifts and daily functional activities in persons with paraplegia: considerations for shoulder health.

Science.gov (United States)

Riek, L M; Ludewig, P M; Nawoczenski, D A

2008-05-01

Case series; nonparametric repeated-measures analysis of variance. To compare and contrast three-dimensional shoulder kinematics during frequently utilized upper extremity weight-bearing activities (standing depression lifts used in brace walking, weight-relief raises, transfers) and postures (sitting rest, standing in a frame) in spinal cord injury (SCI). Movement Analysis Laboratory, Department of Physical Therapy, Ithaca College, Rochester, NY, USA. Three female and two male subjects (39.2+/-6.1 years old) at least 12 months post-SCI (14.6+/-6.7 years old), SCI distal to T2 and with an ASIA score of A. The Flock of Birds magnetic tracking device was used to measure three-dimensional positions of the scapula, humerus and thorax during various activities. Standing in a frame resulted in significantly less scapular anterior tilt (AT) and greater glenohumeral external rotation (GHER) than standing depression lifts and weight-relief raises. Standing frame posture offers the most favorable shoulder joint positions (less scapular AT and greater GHER) when compared to sitting rest posture, weight-relief raises, transfers and standing depression lifts. Knowledge of kinematic patterns associated with each activity is an essential first step to understanding the potential impact on shoulder health. Choosing specific activities or modifying techniques within functional activities that promote favorable shoulder positions may preserve long-term shoulder health.

A comparison of leisure constraints among three outdoor recreation activities: whitewater rafting, canoeing and overnight horseback riding

Science.gov (United States)

Gyan P. Nyaupane; Duarte B. Morais; Alan Graefe

2003-01-01

The purpose of this study was to compare leisure constraints across three outdoor recreation activities, whitewater rafting, canoeing, and overnight horseback riding, in the context of the three-dimensional leisure constraints model proposed by Crawford and Godbey (1987). The sample consisted of 650 outdoor enthusiasts from 14 U.S. states who showed an interest in...

Kinematic control of walking.

Science.gov (United States)

Lacquaniti, F; Ivanenko, Y P; Zago, M

2002-10-01

The planar law of inter-segmental co-ordination we described may emerge from the coupling of neural oscillators between each other and with limb mechanical oscillators. Muscle contraction intervenes at variable times to re-excite the intrinsic oscillations of the system when energy is lost. The hypothesis that a law of coordinative control results from a minimal active tuning of the passive inertial and viscoelastic coupling among limb segments is congruent with the idea that movement has evolved according to minimum energy criteria (1, 8). It is known that multi-segment motion of mammals locomotion is controlled by a network of coupled oscillators (CPGs, see 18, 33, 37). Flexible combination of unit oscillators gives rise to different forms of locomotion. Inter-oscillator coupling can be modified by changing the synaptic strength (or polarity) of the relative spinal connections. As a result, unit oscillators can be coupled in phase, out of phase, or with a variable phase, giving rise to different behaviors, such as speed increments or reversal of gait direction (from forward to backward). Supra-spinal centers may drive or modulate functional sets of coordinating interneurons to generate different walking modes (or gaits). Although it is often assumed that CPGs control patterns of muscle activity, an equally plausible hypothesis is that they control patterns of limb segment motion instead (22). According to this kinematic view, each unit oscillator would directly control a limb segment, alternately generating forward and backward oscillations of the segment. Inter-segmental coordination would be achieved by coupling unit oscillators with a variable phase. Inter-segmental kinematic phase plays the role of global control variable previously postulated for the network of central oscillators. In fact, inter-segmental phase shifts systematically with increasing speed both in man (4) and cat (38). Because this phase-shift is correlated with the net mechanical power

Ontogenetic scaling of locomotor kinetics and kinematics of the ostrich (Struthio camelus).

Science.gov (United States)

Smith, Nicola C; Jespers, Karin J; Wilson, Alan M

2010-04-01

Kinematic and kinetic parameters of running gait were investigated through growth in the ostrich, from two weeks up to 10 months of age, in order to investigate the effects of increasing body size. Ontogenetic scaling relationships were compared with published scaling relationships found to exist with increasing body size between species to determine whether dynamic similarity is maintained during growth. During the study, ostrich mass (M(b)) ranged from 0.7 kg to 108.8 kg. Morphological measurements showed that lengths scaled with positive allometry during growth (hip height proportional to M(b)(0.40); foot segment length proportional to M(b)(0.40); tarsometatarsus length proportional to M(b)(0.41); tibiotarsus length proportional to M(b)(0.38); femur length proportional to M(b)(0.37)), significantly exceeding the close to geometric scaling observed between mammalian and avian species of increasing body size. Scaling of kinematic variables largely agreed with predicted scaling for increasing size and demonstrated relationships close to dynamic similarity and, as such, ontogenetic scaling of locomotor parameters was similar to that observed with increasing body mass between species. However, the ways in which these scaling trends were achieved were very different, with ontogenetic scaling of locomotor mechanics largely resulting from simple scaling of the limb segments rather than postural changes, likely to be due to developmental constraints. Small deviations from dynamic similarity of kinematic parameters and a reduction in the predicted scaling of limb stiffness (proportional to M(b)(0.59)) were found to be accounted for by the positive allometric scaling of the limb during growth.

MAGNETIC QUENCHING OF TURBULENT DIFFUSIVITY: RECONCILING MIXING-LENGTH THEORY ESTIMATES WITH KINEMATIC DYNAMO MODELS OF THE SOLAR CYCLE

International Nuclear Information System (INIS)

Munoz-Jaramillo, Andres; Martens, Petrus C. H.; Nandy, Dibyendu

2011-01-01

The turbulent magnetic diffusivity in the solar convection zone is one of the most poorly constrained ingredients of mean-field dynamo models. This lack of constraint has previously led to controversy regarding the most appropriate set of parameters, as different assumptions on the value of turbulent diffusivity lead to radically different solar cycle predictions. Typically, the dynamo community uses double-step diffusivity profiles characterized by low values of diffusivity in the bulk of the convection zone. However, these low diffusivity values are not consistent with theoretical estimates based on mixing-length theory, which suggest much higher values for turbulent diffusivity. To make matters worse, kinematic dynamo simulations cannot yield sustainable magnetic cycles using these theoretical estimates. In this work, we show that magnetic cycles become viable if we combine the theoretically estimated diffusivity profile with magnetic quenching of the diffusivity. Furthermore, we find that the main features of this solution can be reproduced by a dynamo simulation using a prescribed (kinematic) diffusivity profile that is based on the spatiotemporal geometric average of the dynamically quenched diffusivity. This bridges the gap between dynamically quenched and kinematic dynamo models, supporting their usage as viable tools for understanding the solar magnetic cycle.

Are undesirable contact kinematics minimized after kinematically aligned total knee arthroplasty? An intersurgeon analysis of consecutive patients.

Science.gov (United States)

Howell, Stephen M; Hodapp, Esther E; Vernace, Joseph V; Hull, Maury L; Meade, Thomas D

2013-10-01

Tibiofemoral contact kinematics or knee implant motions have a direct influence on patient function and implant longevity and should be evaluated for any new alignment technique such as kinematically aligned total knee arthroplasty (TKA). Edge loading of the tibial liner and external rotation (reverse of normal) and adduction of the tibial component on the femoral component are undesirable contact kinematics that should be minimized. Accordingly, this study determined whether the overall prevalence of undesirable contact kinematics during standing, mid kneeling near 90 degrees and full kneeling with kinematically aligned TKA are minimal and not different between groups of consecutive patients treated by different surgeons. Three surgeons were asked to perform cemented, kinematically aligned TKA with patient-specific guides in a consecutive series of patients with their preferred cruciate-retaining (CR) implant. In vivo tibiofemoral contact positions were obtained using a 3- to 2-dimensional image registration technique in 69 subjects (Vanguard CR-TKA N = 22, and Triathlon CR-TKA N = 47). Anterior or posterior edge loading of the tibial liner was not observed. The overall prevalence of external rotation of the tibial component on the femoral component of 6 % was low and not different between surgeons (n.s.). The overall prevalence of adduction of the tibial component on the femoral component of 4 % was low and not different between surgeons (n.s.). Kinematically aligned TKA minimized the undesirable contact kinematics of edge loading of the tibial liner, and external rotation and adduction of the tibial component on the femoral component during standing and kneeling, which suggests an optimistic prognosis for durable long-term function. III.

Inverse Kinematic Analysis Of A Quadruped Robot

Directory of Open Access Journals (Sweden)

Muhammed Arif Sen

2017-09-01

Full Text Available This paper presents an inverse kinematics program of a quadruped robot. The kinematics analysis is main problem in the manipulators and robots. Dynamic and kinematic structures of quadruped robots are very complex compared to industrial and wheeled robots. In this study inverse kinematics solutions for a quadruped robot with 3 degrees of freedom on each leg are presented. Denavit-Hartenberg D-H method are used for the forward kinematic. The inverse kinematic equations obtained by the geometrical and mathematical methods are coded in MATLAB. And thus a program is obtained that calculate the legs joint angles corresponding to desired various orientations of robot and endpoints of legs. Also the program provides the body orientations of robot in graphical form. The angular positions of joints obtained corresponding to desired different orientations of robot and endpoints of legs are given in this study.

Investigating The Kinematics of Canids and Felids

Science.gov (United States)

Sur, D.

2016-12-01

For all organisms, metabolic energy is critical for survival. While moving efficiently is a necessity for large carnivores, the influence of kinematics on energy demand remains poorly understood. We measured the kinematics of dogs, wolves, and pumas to detect any differences in their respective energy expenditures. Using 22 kinematic parameters measured on 78 videos, we used one-way ANOVAs and paired T-tests to compare 5 experimental treatments among gaits in dogs (n=11 in 3 breed groups), wolves (n=2), and pumas (n=2). Across the measured parameters, we found greater kinematic similarity than expected among dog breeds and no trend in any of the 22 parameters regarding the effect of steepness on locomotion mechanics. Similarly, treadmill kinematics were nearly identical to those measured during outdoor movement. However, in 3 inches of snow, we observed significant differences (pwolf. When comparing canids (wolves and dogs) to a felid (pumas), we found that pumas and dogs are the most kinematically distinct (differing in 13 of 22 parameters, compared with 5 of 22 for wolves and pumas). Lastly, compared with wolves, walking pumas had larger head angles (p=0.0025), forelimb excursion angles (p=0.0045), and hindlimb excursion angles (p=0.0327). After comparing the energetics of pumas and dogs with their respective kinematics, we noted that less dynamic kinematics result in energy savings. Through tracking the locations and gait behavior of large carnivores, novel sensor technology can reveal how indoor kinematics applies to wild animals and improve the conservation of these species.

Inverse Kinematics With Closed Form Solution For Denso Robot Manipulator

Directory of Open Access Journals (Sweden)

Ikhsan Eka Prasetia

2015-03-01

Full Text Available In this paper, the forward kinematics and inverse kinematics used on the Denso robot manipulator which has a 6-DOF. The forward kinematics will result in the desired position by end-effector, while inverse kinematics produce angel on each joint. Inverse kinematics problem are very difficult, therefor to obtain the solution of inverse kinematics using closed form solution with geometry approach. The simulation result obtained from forward kinematics and inverse kinematics is determining desired position by Denso robot manipulator. Forward kinematics produce the desired position by the end-effector. Inverse kinematics produce joint angle, where the inverse kinematics produce eight conditions obtained from closed form solution with geometry approach to reach the desired position by the end-effector.

Influence of a virtual reality-based exercise protocol on the sit-to-stand activity kinematic variables in pregnant women: a randomized controlled trial

Directory of Open Access Journals (Sweden)

Silvia Oliveira Ribeiro

2017-07-01

Full Text Available Abstract AIMS Changes resulting from the gestational period may lead to changes in the biomechanics of women, which can alter the performance of functional activities such as sit-to-stand. Thus, the objective of this study was to investigate the influence of a virtual reality-based exercise protocol on the kinematic variables of the sit-to-stand movement in women in their second and third gestational trimesters. METHODS The sample consisted of 44 women selected according to the eligibility criteria, allocated into 4 groups: control group, 2nd trimester (CG2T; experimental group, 2nd trimester (EG2T; control group, 3rd trimester (CG3T; and experimental group, 3rd trimester (EG3T. All the volunteers answered the identification and evaluation form and were sent to the kinematic evaluation through the Qualisys Motion Capture System®. An intervention with game therapy was performed in 12 sessions of 30 minutes each, three times a week. RESULTS No statistically significant differences were found intra- (P> 0.54 and inter-groups (P> 0.059 for kinematic variables. However, there was a tendency for improvement in the analyzed variables after the proposed protocol. CONCLUSIONS The data obtained suggest that the use of the Nintendo Wii Fit Plus® was not able to influence sit-to-stand kinematic variables in the analyzed women.

Inverse Kinematics

Directory of Open Access Journals (Sweden)

Joel Sereno

2010-01-01

Full Text Available Inverse kinematics is the process of converting a Cartesian point in space into a set of joint angles to more efficiently move the end effector of a robot to a desired orientation. This project investigates the inverse kinematics of a robotic hand with fingers under various scenarios. Assuming the parameters of a provided robot, a general equation for the end effector point was calculated and used to plot the region of space that it can reach. Further, the benefits obtained from the addition of a prismatic joint versus an extra variable angle joint were considered. The results confirmed that having more movable parts, such as prismatic points and changing angles, increases the effective reach of a robotic hand.

Inverse Kinematics With Closed Form Solution For Denso Robot Manipulator

OpenAIRE

Ikhsan Eka Prasetia; Trihastuti Agustinah

2015-01-01

In this paper, the forward kinematics and inverse kinematics used on the Denso robot manipulator which has a 6-DOF. The forward kinematics will result in the desired position by end-effector, while inverse kinematics produce angel on each joint. Inverse kinematics problem are very difficult, therefor to obtain the solution of inverse kinematics using closed form solution with geometry approach. The simulation result obtained from forward kinematics and inverse kinematics is determining desire...

Data assimilation with inequality constraints

Science.gov (United States)

Thacker, W. C.

If values of variables in a numerical model are limited to specified ranges, these restrictions should be enforced when data are assimilated. The simplest option is to assimilate without regard for constraints and then to correct any violations without worrying about additional corrections implied by correlated errors. This paper addresses the incorporation of inequality constraints into the standard variational framework of optimal interpolation with emphasis on our limited knowledge of the underlying probability distributions. Simple examples involving only two or three variables are used to illustrate graphically how active constraints can be treated as error-free data when background errors obey a truncated multi-normal distribution. Using Lagrange multipliers, the formalism is expanded to encompass the active constraints. Two algorithms are presented, both relying on a solution ignoring the inequality constraints to discover violations to be enforced. While explicitly enforcing a subset can, via correlations, correct the others, pragmatism based on our poor knowledge of the underlying probability distributions suggests the expedient of enforcing them all explicitly to avoid the computationally expensive task of determining the minimum active set. If additional violations are encountered with these solutions, the process can be repeated. Simple examples are used to illustrate the algorithms and to examine the nature of the corrections implied by correlated errors.

Influence of gravity compensation on kinematics and muscle activation patterns during reach and retrieval in subjects with cervical spinal cord injury An explorative study

NARCIS (Netherlands)

Kloosterman, Marieke G. M.; Snoek, Govert J.; Kouwenhoven, Mirjam; Nene, Anand V.; Jannink, Michiel J. A.

2010-01-01

Many interventions in upper-limb rehabilitation after cervical spinal cord injury (CSCI) use arm support (gravity compensation), however, its specific effects on kinematics and muscle activation characteristics in subjects with a CSCI are largely unknown We conducted a cross-sectional explorative

Study of the Navigation Method for a Snake Robot Based on the Kinematics Model with MEMS IMU

Science.gov (United States)

Dou, Lihua; Su, Zhong; Liu, Ning

2018-01-01

A snake robot is a type of highly redundant mobile robot that significantly differs from a tracked robot, wheeled robot and legged robot. To address the issue of a snake robot performing self-localization in the application environment without assistant orientation, an autonomous navigation method is proposed based on the snake robot’s motion characteristic constraints. The method realized the autonomous navigation of the snake robot with non-nodes and an external assistant using its own Micro-Electromechanical-Systems (MEMS) Inertial-Measurement-Unit (IMU). First, it studies the snake robot’s motion characteristics, builds the kinematics model, and then analyses the motion constraint characteristics and motion error propagation properties. Second, it explores the snake robot’s navigation layout, proposes a constraint criterion and the fixed relationship, and makes zero-state constraints based on the motion features and control modes of a snake robot. Finally, it realizes autonomous navigation positioning based on the Extended-Kalman-Filter (EKF) position estimation method under the constraints of its motion characteristics. With the self-developed snake robot, the test verifies the proposed method, and the position error is less than 5% of Total-Traveled-Distance (TDD). In a short-distance environment, this method is able to meet the requirements of a snake robot in order to perform autonomous navigation and positioning in traditional applications and can be extended to other familiar multi-link robots. PMID:29547515

Study of the Navigation Method for a Snake Robot Based on the Kinematics Model with MEMS IMU.

Science.gov (United States)

Zhao, Xu; Dou, Lihua; Su, Zhong; Liu, Ning

2018-03-16

A snake robot is a type of highly redundant mobile robot that significantly differs from a tracked robot, wheeled robot and legged robot. To address the issue of a snake robot performing self-localization in the application environment without assistant orientation, an autonomous navigation method is proposed based on the snake robot's motion characteristic constraints. The method realized the autonomous navigation of the snake robot with non-nodes and an external assistant using its own Micro-Electromechanical-Systems (MEMS) Inertial-Measurement-Unit (IMU). First, it studies the snake robot's motion characteristics, builds the kinematics model, and then analyses the motion constraint characteristics and motion error propagation properties. Second, it explores the snake robot's navigation layout, proposes a constraint criterion and the fixed relationship, and makes zero-state constraints based on the motion features and control modes of a snake robot. Finally, it realizes autonomous navigation positioning based on the Extended-Kalman-Filter (EKF) position estimation method under the constraints of its motion characteristics. With the self-developed snake robot, the test verifies the proposed method, and the position error is less than 5% of Total-Traveled-Distance (TDD). In a short-distance environment, this method is able to meet the requirements of a snake robot in order to perform autonomous navigation and positioning in traditional applications and can be extended to other familiar multi-link robots.

Dwarf galaxy dark matter density profiles inferred from stellar and gas kinematics

International Nuclear Information System (INIS)

Adams, Joshua J.; Simon, Joshua D.; Fabricius, Maximilian H.; Bender, Ralf; Thomas, Jens; Van den Bosch, Remco C. E.; Van de Ven, Glenn; Barentine, John C.; Gebhardt, Karl; Hill, Gary J.; Murphy, Jeremy D.; Swaters, R. A.

2014-01-01

We present new constraints on the density profiles of dark matter (DM) halos in seven nearby dwarf galaxies from measurements of their integrated stellar light and gas kinematics. The gas kinematics of low-mass galaxies frequently suggest that they contain constant density DM cores, while N-body simulations instead predict a cuspy profile. We present a data set of high-resolution integral-field spectroscopy on seven galaxies and measure the stellar and gas kinematics simultaneously. Using Jeans modeling on our full sample, we examine whether gas kinematics in general produce shallower density profiles than are derived from the stars. Although two of the seven galaxies show some localized differences in their rotation curves between the two tracers, estimates of the central logarithmic slope of the DM density profile, γ, are generally robust. The mean and standard deviation of the logarithmic slope for the population are γ = 0.67 ± 0.10 when measured in the stars and γ = 0.58 ± 0.24 when measured in the gas. We also find that the halos are not under-concentrated at the radii of half their maximum velocities. Finally, we search for correlations of the DM density profile with stellar velocity anisotropy and other baryonic properties. Two popular mechanisms to explain cored DM halos are an exotic DM component or feedback models that strongly couple the energy of supernovae into repeatedly driving out gas and dynamically heating the DM halos. While such models do not yet have falsifiable predictions that we can measure, we investigate correlations that may eventually be used to test models. We do not find a secondary parameter that strongly correlates with the central DM density slope, but we do find some weak correlations. The central DM density slope weakly correlates with the abundance of α elements in the stellar population, anti-correlates with H I fraction, and anti-correlates with vertical orbital anisotropy. We expect, if anything, the opposite of these

Astrophysical constraints on Planck scale dissipative phenomena.

Science.gov (United States)

Liberati, Stefano; Maccione, Luca

2014-04-18

The emergence of a classical spacetime from any quantum gravity model is still a subtle and only partially understood issue. If indeed spacetime is arising as some sort of large scale condensate of more fundamental objects, then it is natural to expect that matter, being a collective excitation of the spacetime constituents, will present modified kinematics at sufficiently high energies. We consider here the phenomenology of the dissipative effects necessarily arising in such a picture. Adopting dissipative hydrodynamics as a general framework for the description of the energy exchange between collective excitations and the spacetime fundamental degrees of freedom, we discuss how rates of energy loss for elementary particles can be derived from dispersion relations and used to provide strong constraints on the base of current astrophysical observations of high-energy particles.

Inverse kinematic-based robot control

Science.gov (United States)

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

1987-01-01

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

Fiber-reinforced materials: finite elements for the treatment of the inextensibility constraint

Science.gov (United States)

Auricchio, Ferdinando; Scalet, Giulia; Wriggers, Peter

2017-12-01

The present paper proposes a numerical framework for the analysis of problems involving fiber-reinforced anisotropic materials. Specifically, isotropic linear elastic solids, reinforced by a single family of inextensible fibers, are considered. The kinematic constraint equation of inextensibility in the fiber direction leads to the presence of an undetermined fiber stress in the constitutive equations. To avoid locking-phenomena in the numerical solution due to the presence of the constraint, mixed finite elements based on the Lagrange multiplier, perturbed Lagrangian, and penalty method are proposed. Several boundary-value problems under plane strain conditions are solved and numerical results are compared to analytical solutions, whenever the derivation is possible. The performed simulations allow to assess the performance of the proposed finite elements and to discuss several features of the developed formulations concerning the effective approximation for the displacement and fiber stress fields, mesh convergence, and sensitivity to penalty parameters.

Electron beam gun with kinematic coupling for high power RF vacuum devices

Science.gov (United States)

Borchard, Philipp

2016-11-22

An electron beam gun for a high power RF vacuum device has components joined by a fixed kinematic coupling to provide both precise alignment and high voltage electrical insulation of the components. The kinematic coupling has high strength ceramic elements directly bonded to one or more non-ductile rigid metal components using a high temperature active metal brazing alloy. The ceramic elements have a convex surface that mates with concave grooves in another one of the components. The kinematic coupling, for example, may join a cathode assembly and/or a beam shaping focus electrode to a gun stem, which is preferably composed of ceramic. The electron beam gun may be part of a high power RF vacuum device such as, for example, a gyrotron, klystron, or magnetron.

Kinematics and dynamics analysis of a quadruped walking robot with parallel leg mechanism

Science.gov (United States)

Wang, Hongbo; Sang, Lingfeng; Hu, Xing; Zhang, Dianfan; Yu, Hongnian

2013-09-01

It is desired to require a walking robot for the elderly and the disabled to have large capacity, high stiffness, stability, etc. However, the existing walking robots cannot achieve these requirements because of the weight-payload ratio and simple function. Therefore, Improvement of enhancing capacity and functions of the walking robot is an important research issue. According to walking requirements and combining modularization and reconfigurable ideas, a quadruped/biped reconfigurable walking robot with parallel leg mechanism is proposed. The proposed robot can be used for both a biped and a quadruped walking robot. The kinematics and performance analysis of a 3-UPU parallel mechanism which is the basic leg mechanism of a quadruped walking robot are conducted and the structural parameters are optimized. The results show that performance of the walking robot is optimal when the circumradius R, r of the upper and lower platform of leg mechanism are 161.7 mm, 57.7 mm, respectively. Based on the optimal results, the kinematics and dynamics of the quadruped walking robot in the static walking mode are derived with the application of parallel mechanism and influence coefficient theory, and the optimal coordination distribution of the dynamic load for the quadruped walking robot with over-determinate inputs is analyzed, which solves dynamic load coupling caused by the branches’ constraint of the robot in the walk process. Besides laying a theoretical foundation for development of the prototype, the kinematics and dynamics studies on the quadruped walking robot also boost the theoretical research of the quadruped walking and the practical applications of parallel mechanism.

Constraint-based Attribute and Interval Planning

Science.gov (United States)

Jonsson, Ari; Frank, Jeremy

2013-01-01

In this paper we describe Constraint-based Attribute and Interval Planning (CAIP), a paradigm for representing and reasoning about plans. The paradigm enables the description of planning domains with time, resources, concurrent activities, mutual exclusions among sets of activities, disjunctive preconditions and conditional effects. We provide a theoretical foundation for the paradigm, based on temporal intervals and attributes. We then show how the plans are naturally expressed by networks of constraints, and show that the process of planning maps directly to dynamic constraint reasoning. In addition, we de ne compatibilities, a compact mechanism for describing planning domains. We describe how this framework can incorporate the use of constraint reasoning technology to improve planning. Finally, we describe EUROPA, an implementation of the CAIP framework.

Knee and Hip Joint Kinematics Predict Quadriceps and Hamstrings Neuromuscular Activation Patterns in Drop Jump Landings.

Science.gov (United States)

Malfait, Bart; Dingenen, Bart; Smeets, Annemie; Staes, Filip; Pataky, Todd; Robinson, Mark A; Vanrenterghem, Jos; Verschueren, Sabine

2016-01-01

The purpose was to assess if variation in sagittal plane landing kinematics is associated with variation in neuromuscular activation patterns of the quadriceps-hamstrings muscle groups during drop vertical jumps (DVJ). Fifty female athletes performed three DVJ. The relationship between peak knee and hip flexion angles and the amplitude of four EMG vectors was investigated with trajectory-level canonical correlation analyses over the entire time period of the landing phase. EMG vectors consisted of the {vastus medialis(VM),vastus lateralis(VL)}, {vastus medialis(VM),hamstring medialis(HM)}, {hamstring medialis(HM),hamstring lateralis(HL)} and the {vastus lateralis(VL),hamstring lateralis(HL)}. To estimate the contribution of each individual muscle, linear regressions were also conducted using one-dimensional statistical parametric mapping. The peak knee flexion angle was significantly positively associated with the amplitudes of the {VM,HM} and {HM,HL} during the preparatory and initial contact phase and with the {VL,HL} vector during the peak loading phase (phamstrings medialis activity) during the preparatory and initial contact phase and an increased lateral neuromuscular activation (dominant vastus lateralis activity) during the peak loading phase.

Kinematic aspects of pion-nucleus elastic scattering

International Nuclear Information System (INIS)

Weiss, D.L.; Ernst, D.J.

1982-01-01

The inclusion of relativistic kinematics in the theory of elastic scattering of pions from nuclei is examined. The investigation is performed in the context of the first order impulse approximation which incorporates the following features: (1) Relative momentum are defined according to relativistic theories consistent with time reversal invariance. (2) The two-nucleon interaction is a new, multichannel, separable potential model consistent with the most recent data derived from a recent nonpotential model of Ernst and Johnson. (3) The recoil of the pion-nucleon interacting pair and its resultant nonlocality are included. (4) The Fermi integral is treated by an optimal factorization approximation. It is shown how a careful definition of an intrinsic target density leads to an unambiguous method for including the recoil of the target. The target recoil corrections are found to be large for elastic scattering from 4 He and not negligible for scattering from 12 C. Relativistic potential theory kinematics, kinematics which result from covariant reduction approaches, and kinematics which result from replacing masses by energies in nonrelativistic formulas are compared. The relativistic potential theory kinematics and covariant reduction kinematics are shown to produce different elastic scattering at all pion energies examined (T/sub π/<300 MeV). Simple extensions of nonrelativistic kinematics are found to be reasonable approximations to relativistic potential theory

Cortical Decoding of Individual Finger and Wrist Kinematics for an Upper-Limb Neuroprosthesis

Science.gov (United States)

Aggarwal, Vikram; Tenore, Francesco; Acharya, Soumyadipta; Schieber, Marc H.; Thakor, Nitish V.

2010-01-01

Previous research has shown that neuronal activity can be used to continuously decode the kinematics of gross movements involving arm and hand trajectory. However, decoding the kinematics of fine motor movements, such as the manipulation of individual fingers, has not been demonstrated. In this study, single unit activities were recorded from task-related neurons in M1 of two trained rhesus monkey as they performed individuated movements of the fingers and wrist. The primates’ hand was placed in a manipulandum, and strain gauges at the tips of each finger were used to track the digit’s position. Both linear and non-linear filters were designed to simultaneously predict kinematics of each digit and the wrist, and their performance compared using mean squared error and correlation coefficients. All models had high decoding accuracy, but the feedforward ANN (R=0.76–0.86, MSE=0.04–0.05) and Kalman filter (R=0.68–0.86, MSE=0.04–0.07) performed better than a simple linear regression filter (0.58–0.81, 0.05–0.07). These results suggest that individual finger and wrist kinematics can be decoded with high accuracy, and be used to control a multi-fingered prosthetic hand in real-time. PMID:19964645

VRACK: measuring pedal kinematics during stationary bike cycling.

Science.gov (United States)

Farjadian, Amir B; Kong, Qingchao; Gade, Venkata K; Deutsch, Judith E; Mavroidis, Constantinos

2013-06-01

Ankle impairment and lower limb asymmetries in strength and coordination are common symptoms for individuals with selected musculoskeletal and neurological impairments. The virtual reality augmented cycling kit (VRACK) was designed as a compact mechatronics system for lower limb and mobility rehabilitation. The system measures interaction forces and cardiac activity during cycling in a virtual environment. The kinematics measurement was added to the system. Due to the constrained problem definition, the combination of inertial measurement unit (IMU) and Kalman filtering was recruited to compute the optimal pedal angular displacement during dynamic cycling exercise. Using a novel benchmarking method the accuracy of IMU-based kinematics measurement was evaluated. Relatively accurate angular measurements were achieved. The enhanced VRACK system can serve as a rehabilitation device to monitor biomechanical and physiological variables during cycling on a stationary bike.

Kinematic design of a finger abduction mechanism for an anthropomorphic robotic hand

Directory of Open Access Journals (Sweden)

L.-A. A. Demers

2011-02-01

Full Text Available This paper presents the kinematic design of an abduction mechanism for the fingers of an underactuated anthropomorphic robotic hand. This mechanism will enhance the range of feasible grasps of the underactuated hand without significantly increasing its complexity. The analysis of the link between the index finger and the third finger is first assessed, where the parameters are studied in order to follow the amplitude constraint and to minimize the coordination error. Then, the study of the mechanism joining the third finger and the little finger is summarized. Finally, a prototype of the finger's abduction system is presented.

This paper was presented at the IFToMM/ASME International Workshop on Underactuated Grasping (UG2010, 19 August 2010, Montréal, Canada.

Kinematic relations in heavy-ion reactions

International Nuclear Information System (INIS)

Gippner, P.; Kalpakchieva, R.

1988-01-01

The present work gives a short overview of the non-relativistic kinematics of nuclear reactions derived on the basis of the conservation laws of energy and linear momentum. Section 2 contains kinematic relations valid for two-body reactions, sections 3 makes use of these relations to describe sequential fission as a special case of reactions with three particles in the exit channel. It is the aim of this work to comprise the kinematic formulae essential for planning of experiments, data analysis and critical examination of the obtained results. (author)

Effects of Juvenile Idiopathic Arthritis on Kinematics and Kinetics of the Lower Extremities Call for Consequences in Physical Activities Recommendations

OpenAIRE

Hartmann, M.; Kreuzpointner, F.; Haefner, R.; Michels, H.; Schwirtz, A.; Haas, J. P.

2010-01-01

Juvenile idiopathic arthritis (JIA) patients (n = 36) with symmetrical polyarticular joint involvement of the lower extremities and healthy controls (n = 20) were compared concerning differences in kinematic, kinetic, and spatio-temporal parameters with 3D gait analysis. The aims of this study were to quantify the differences in gait between JIA patients and healthy controls and to provide data for more detailed sport activities recommendations. JIA-patients showed reduced walking speed and s...

Kinematic adjustments to seismic recordings

Energy Technology Data Exchange (ETDEWEB)

Telegin, A.N.; Levii, N.V.; Volovik, U.M.

1981-01-01

The introduction of kinematic adjustments by adding the displaced blocks is studied theoretically and in test seismograms. The advantage to this method resulting from the weight variation in the trace is demonstrated together with its kinematic drawback. A variation on the displaced block addition method that does not involve realignment of the travel time curves and that has improved amplitude characteristics is proposed.

Biquaternions and relativistic kinematics

International Nuclear Information System (INIS)

Bogush, A.A.; Kurochkin, Yu.A.; Fedorov, F.I.

1979-01-01

The problems concerning the use of quaternion interpretation of the Lorentz group vector parametrization are considered for solving relativistic kinematics problems. A vector theory convenient for describing the characteristic features of the Lobachevsky space is suggested. The kinematics of elementary particle scattering is investigated on the basis of this theory. A synthesis of vector parametrization and of quaternion calculation has been shown to lead to natural formulation of the theory of vectors in the three-dimensional Lobachevsky space, realized on mass hyperboloids of relativistic particles

Study of the Navigation Method for a Snake Robot Based on the Kinematics Model with MEMS IMU

Directory of Open Access Journals (Sweden)

Xu Zhao

2018-03-01

Full Text Available A snake robot is a type of highly redundant mobile robot that significantly differs from a tracked robot, wheeled robot and legged robot. To address the issue of a snake robot performing self-localization in the application environment without assistant orientation, an autonomous navigation method is proposed based on the snake robot’s motion characteristic constraints. The method realized the autonomous navigation of the snake robot with non-nodes and an external assistant using its own Micro-Electromechanical-Systems (MEMS Inertial-Measurement-Unit (IMU. First, it studies the snake robot’s motion characteristics, builds the kinematics model, and then analyses the motion constraint characteristics and motion error propagation properties. Second, it explores the snake robot’s navigation layout, proposes a constraint criterion and the fixed relationship, and makes zero-state constraints based on the motion features and control modes of a snake robot. Finally, it realizes autonomous navigation positioning based on the Extended-Kalman-Filter (EKF position estimation method under the constraints of its motion characteristics. With the self-developed snake robot, the test verifies the proposed method, and the position error is less than 5% of Total-Traveled-Distance (TDD. In a short-distance environment, this method is able to meet the requirements of a snake robot in order to perform autonomous navigation and positioning in traditional applications and can be extended to other familiar multi-link robots.

Climbing fibers predict movement kinematics and performance errors.

Science.gov (United States)

Streng, Martha L; Popa, Laurentiu S; Ebner, Timothy J

2017-09-01

Requisite for understanding cerebellar function is a complete characterization of the signals provided by complex spike (CS) discharge of Purkinje cells, the output neurons of the cerebellar cortex. Numerous studies have provided insights into CS function, with the most predominant view being that they are evoked by error events. However, several reports suggest that CSs encode other aspects of movements and do not always respond to errors or unexpected perturbations. Here, we evaluated CS firing during a pseudo-random manual tracking task in the monkey ( Macaca mulatta ). This task provides extensive coverage of the work space and relative independence of movement parameters, delivering a robust data set to assess the signals that activate climbing fibers. Using reverse correlation, we determined feedforward and feedback CSs firing probability maps with position, velocity, and acceleration, as well as position error, a measure of tracking performance. The direction and magnitude of the CS modulation were quantified using linear regression analysis. The major findings are that CSs significantly encode all three kinematic parameters and position error, with acceleration modulation particularly common. The modulation is not related to "events," either for position error or kinematics. Instead, CSs are spatially tuned and provide a linear representation of each parameter evaluated. The CS modulation is largely predictive. Similar analyses show that the simple spike firing is modulated by the same parameters as the CSs. Therefore, CSs carry a broader array of signals than previously described and argue for climbing fiber input having a prominent role in online motor control. NEW & NOTEWORTHY This article demonstrates that complex spike (CS) discharge of cerebellar Purkinje cells encodes multiple parameters of movement, including motor errors and kinematics. The CS firing is not driven by error or kinematic events; instead it provides a linear representation of each

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

Science.gov (United States)

Nguyen, Charles C.; Pooran, Farhad J.

1989-01-01

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

Interrelationship of motivation for and perceived constraints to physical activity participation and the well-being of senior center participants

Science.gov (United States)

Motoko Miyake; Ellen Rodgers

2009-01-01

This study investigated the relationship of motivation for and perceived constraints to physical activity (PA) participation and the well-being of senior center participants. A survey instrument made up of modified versions of the Sport Motivation and Perceived Constraints Scales, the Life Satisfaction Index-Z, and the Geriatric Depression Scale was administered at the...

Beyond reward prediction errors: the role of dopamine in movement kinematics

Directory of Open Access Journals (Sweden)

Joseph eBarter

2015-05-01

Full Text Available We recorded activity of dopamine (DA neurons in the substantia nigra pars compacta in unrestrained mice while monitoring their movements with video tracking. Our approach allows an unbiased examination of the continuous relationship between single unit activity and behavior. Although DA neurons show characteristic burst firing following cue or reward presentation, as previously reported, their activity can be explained by the representation of actual movement kinematics. Unlike neighboring pars reticulata GABAergic output neurons, which can represent vector components of position, DA neurons represent vector components of velocity or acceleration. We found neurons related to movements in four directions—up, down, left right. For horizontal movements, there is significant lateralization of neurons: the left nigra contains more rightward neurons, whereas the right nigra contains more leftward neurons. The relationship between DA activity and movement kinematics was found on both appetitive trials using sucrose and aversive trials using air puff, showing that these neurons belong to a velocity control circuit that can be used for any number of purposes, whether to seek reward or to avoid harm. In support of this conclusion, mimicry of the phasic activation of DA neurons with selective optogenetic stimulation could also generate movements. Contrary to the popular hypothesis that DA neurons encode reward prediction errors, our results suggest that nigrostriatal DA plays an essential role in controlling the kinematics of voluntary movements. We hypothesize that DA signaling implements gain adjustment for adaptive transition control, and describe a new model of BG in which DA functions to adjust the gain of a transition controller. This model has significant implications for our understanding of movement disorders implicating DA and the BG.

Properties of kinematic singularities

Energy Technology Data Exchange (ETDEWEB)

Coley, A A [Department of Mathematics and Statistics, Dalhousie University, Halifax, Nova Scotia B3H 3J5 (Canada); Hervik, S [Department of Mathematics and Natural Sciences, University of Stavanger, N-4036 Stavanger (Norway); Lim, W C [Albert-Einstein-Institut, Am Muehlenberg 1, D-14476 Potsdam (Germany); MacCallum, M A H, E-mail: aac@mathstat.dal.c, E-mail: sigbjorn.hervik@uis.n, E-mail: wclim@aei.mpg.d, E-mail: m.a.h.maccallum@qmul.ac.u [School of Mathematical Sciences, Queen Mary University of London, E1 4NS (United Kingdom)

2009-11-07

The locally rotationally symmetric tilted perfect fluid Bianchi type V cosmological model provides examples of future geodesically complete spacetimes that admit a 'kinematic singularity' at which the fluid congruence is inextendible but all frame components of the Weyl and Ricci tensors remain bounded. We show that for any positive integer n there are examples of Bianchi type V spacetimes admitting a kinematic singularity such that the covariant derivatives of the Weyl and Ricci tensors up to the nth order also stay bounded. We briefly discuss singularities in classical spacetimes.

The influence of end constraints on smooth pipe bends

International Nuclear Information System (INIS)

Thomson, G.; Spence, J.

1981-01-01

With present trends in the power industries towards higher operating temperatures and pressures, problems associated with the design and safety assessment of pipework systems have become increasingly complex. Within such systems, the importance of smooth pipe bends is well established. The work which will be presented will attempt to clarify the situation and unify the results. An analytical solution of the problem of a linear elastic smooth pipe bend with end constraints under in-plane bending will be presented. The analysis will deal with constraints in the form of flanged tangents of any length. The analysis employs the theorem of minimum total potential energy with suitable kinematically admissible displacements in the form of Fourier series. The integrations and minimisation were performed numerically, thereby permitting the removal of several of the assumptions made by previous authors. Typical results for flexibilities will be given along with comparisons with other works. The differences in some earlier theory are clarified and other more recent work using different solution techniques is substantiated. The bend behaviour is shown to be strongly influenced by the pipe bend parameter, the bend angle, the tangent pipe length and the bend/cross-sectional radius ratio. (orig./GL)

The Ambiguous Role of Constraints in Creativity

DEFF Research Database (Denmark)

Biskjær, Michael Mose; Onarheim, Balder; Wiltschnig, Stefan

2011-01-01

The relationship between creativity and constraints is often described in the literature either in rather imprecise, general concepts or in relation to very specific domains. Cross-domain and cross-disciplinary takes on how the handling of constraints influences creative activities are rare. In t......-disciplinary research into the ambiguous role of constraints in creativity....

3D in vivo femoro-tibial kinematics of tri-condylar total knee arthroplasty during kneeling activities.

Science.gov (United States)

Nakamura, Shinichiro; Sharma, Adrija; Kobayashi, Masahiko; Ito, Hiromu; Nakamura, Kenji; Zingde, Sumesh M; Nakamura, Takashi; Komistek, Richard D

2014-01-01

Kneeling position can serve as an important posture, providing stability and balance from a standing position to sitting on the floor or vice-versa. The purpose of the current study was to determine the kinematics during kneeling activities after subjects were implanted with a tri-condylar total knee arthroplasty. Kinematics was evaluated in 54 knees using fluoroscopy and a three-dimensional model fitting approach. The average knee flexion at before contact status, at complete contact and at maximum flexion was 98.1±9.0°, 107.2±6.7°, and 139.6±12.3°, respectively. On average, there was no gross anterior displacement from before contact status to complete contact. Only slight posterior rollback motion of both condyles from complete contact to maximum flexion was observed. Three of 39 (7.7%) knees experienced anterior movement of both condyles more than 2mm from before contact status to complete contact. Reverse rotation pattern from before contact status to complete contact and then normal rotation pattern from complete contact to maximum flexion were observed. Condylar lift-off greater than 1.0 mm was observed in 45 knees (83.3%). The presence of the ball-and-socket joint articulation provides sufficient antero-posterior stability in these designs to enable the patients to kneel safely without the incidence of any dislocation. This study suggests a safe implant design for kneeling. © 2013.

Kinematic Chains in Ski Jumping In-run Posture.

Science.gov (United States)

Janurová, Eva; Janura, Miroslav; Cabell, Lee; Svoboda, Zdeněk; Vařeka, Ivan; Elfmark, Milan

2013-12-18

The concept of kinematic chains has been systematically applied to biological systems since the 1950s. The course of a ski jump can be characterized as a change between closed and open kinematic chains. The purpose of this study was to determine a relationship between adjacent segments within the ski jumper's body's kinematic chain during the in-run phase of the ski jump. The in-run positions of 267 elite male ski jumpers who participated in the FIS World Cup events in Innsbruck, Austria, between 1992 and 2001 were analyzed (656 jumps). Two-dimensional (2-D) kinematic data were collected from the bodies of the subjects. Relationships between adjacent segments of the kinematic chain in the ski jumper's body at the in-run position are greater nearer the chain's ground contact. The coefficient of determination between the ankle and knee joint angles is 0.67. Changes in the segments' positions in the kinematic chain of the ski jumper's body are stable during longitudinal assessment. Changes in shank and thigh positions, in the sense of increase or decrease, are the same.

Kinematically Optimal Robust Control of Redundant Manipulators

Science.gov (United States)

Galicki, M.

2017-12-01

This work deals with the problem of the robust optimal task space trajectory tracking subject to finite-time convergence. Kinematic and dynamic equations of a redundant manipulator are assumed to be uncertain. Moreover, globally unbounded disturbances are allowed to act on the manipulator when tracking the trajectory by the endeffector. Furthermore, the movement is to be accomplished in such a way as to minimize both the manipulator torques and their oscillations thus eliminating the potential robot vibrations. Based on suitably defined task space non-singular terminal sliding vector variable and the Lyapunov stability theory, we derive a class of chattering-free robust kinematically optimal controllers, based on the estimation of transpose Jacobian, which seem to be effective in counteracting both uncertain kinematics and dynamics, unbounded disturbances and (possible) kinematic and/or algorithmic singularities met on the robot trajectory. The numerical simulations carried out for a redundant manipulator of a SCARA type consisting of the three revolute kinematic pairs and operating in a two-dimensional task space, illustrate performance of the proposed controllers as well as comparisons with other well known control schemes.

The Kinematics of Multiple-peaked Lyα Emission in Star-forming Galaxies at z ~ 2-3

Science.gov (United States)

Kulas, Kristin R.; Shapley, Alice E.; Kollmeier, Juna A.; Zheng, Zheng; Steidel, Charles C.; Hainline, Kevin N.

2012-01-01

We present new results on the Lyα emission-line kinematics of 18 z ~ 2-3 star-forming galaxies with multiple-peaked Lyα profiles. With our large spectroscopic database of UV-selected star-forming galaxies at these redshifts, we have determined that ~30% of such objects with detectable Lyα emission display multiple-peaked emission profiles. These profiles provide additional constraints on the escape of Lyα photons due to the rich velocity structure in the emergent line. Despite recent advances in modeling the escape of Lyα from star-forming galaxies at high redshifts, comparisons between models and data are often missing crucial observational information. Using Keck II NIRSPEC spectra of Hα (z ~ 2) and [O III]λ5007 (z ~ 3), we have measured accurate systemic redshifts, rest-frame optical nebular velocity dispersions, and emission-line fluxes for the objects in the sample. In addition, rest-frame UV luminosities and colors provide estimates of star formation rates and the degree of dust extinction. In concert with the profile sub-structure, these measurements provide critical constraints on the geometry and kinematics of interstellar gas in high-redshift galaxies. Accurate systemic redshifts allow us to translate the multiple-peaked Lyα profiles into velocity space, revealing that the majority (11/18) display double-peaked emission straddling the velocity-field zero point with stronger red-side emission. Interstellar absorption-line kinematics suggest the presence of large-scale outflows for the majority of objects in our sample, with an average measured interstellar absorption velocity offset of langΔv absrang = -230 km s-1. A comparison of the interstellar absorption kinematics for objects with multiple- and single-peaked Lyα profiles indicate that the multiple-peaked objects are characterized by significantly narrower absorption line widths. We compare our data with the predictions of simple models for outflowing and infalling gas distributions around

Shoulder kinematics and spatial pattern of trapezius electromyographic activity in real and virtual environments.

Directory of Open Access Journals (Sweden)

Afshin Samani

Full Text Available The design of an industrial workstation tends to include ergonomic assessment steps based on a digital mock-up and a virtual reality setup. Lack of interaction and system fidelity is often reported as a main issue in such virtual reality applications. This limitation is a crucial issue as thorough ergonomic analysis is required for an investigation of the biomechanics. In the current study, we investigated the biomechanical responses of the shoulder joint in a simulated assembly task for comparison with the biomechanical responses in virtual environments. Sixteen male healthy novice subjects performed the task on three different platforms: real (RE, virtual (VE, and virtual environment with force feedback (VEF with low and high precision demands. The subjects repeated the task 12 times (i.e., 12 cycles. High density electromyography from the upper trapezius and rotation angles of the shoulder joint were recorded and split into the cycles. The angular trajectories and velocity profiles of the shoulder joint angles over a cycle were computed in 3D. The inter-subject similarity in terms of normalized mutual information on kinematics and electromyography was investigated. Compared with RE the task in VE and VEF was characterized by lower kinematic maxima. The inter-subject similarity in RE compared with intra-subject similarity across the platforms was lower in terms of movement trajectories and greater in terms of trapezius muscle activation. The precision demand resulted in lower inter- and intra-subject similarity across platforms. The proposed approach identifies biomechanical differences in the shoulder joint in both VE and VEF compared with the RE platform, but these differences are less marked in VE mostly due to technical limitations of co-localizing the force feedback system in the VEF platform.

Temporal components of the motor patterns expressed by the human spinal cord reflect foot kinematics.

Science.gov (United States)

Ivanenko, Yuri P; Grasso, Renato; Zago, Myrka; Molinari, Marco; Scivoletto, Giorgio; Castellano, Vincenzo; Macellari, Velio; Lacquaniti, Francesco

2003-11-01

What are the building blocks with which the human spinal cord constructs the motor patterns of locomotion? In principle, they could correspond to each individual activity pattern in dozens of different muscles. Alternatively, there could exist a small set of constituent temporal components that are common to all activation patterns and reflect global kinematic goals. To address this issue, we studied patients with spinal injury trained to step on a treadmill with body weight support. Patients learned to produce foot kinematics similar to that of healthy subjects but with activity patterns of individual muscles generally different from the control group. Hidden in the muscle patterns, we found a basic set of five temporal components, whose flexible combination accounted for the wide range of muscle patterns recorded in both controls and patients. Furthermore, two of the components were systematically related to foot kinematics across different stepping speeds and loading conditions. We suggest that the components are related to control signals output by spinal pattern generators, normally under the influence of descending and afferent inputs.

A robotic exoskeleton to treat crouch gait from cerebral palsy: Initial kinematic and neuromuscular evaluation.

Science.gov (United States)

Lerner, Zachary F; Damiano, Diane L; Bulea, Thomas C

2016-08-01

A robotic exoskeleton was designed for individuals with crouch gait caused by cerebral palsy with the intent to supplement existing muscle function during walking. The aim of this study was to evaluate how powered knee extension assistance provided during stance and swing phases of the gait cycle affect knee kinematics, and knee flexor and extensor muscle activity. Muscle activity and kinematic data were collected from four individuals with crouch gait from cerebral palsy during their normal walking condition and while walking with the exoskeleton under stance, swing, and stance & swing assistance. The exoskeleton was effective in reducing crouch by an average of 13.8° in three of the four participants when assistance was provided during the stance phase; assistance during the swing phase alone was ineffective. Peak knee extensor activity was maintained for all of the conditions during the stance and swing phases. Integrated (i.e. area under the curve) knee extensor activity decreased in two of the subjects indicating a more well-modulated activation pattern. Modest increases in peak and integrated antagonist knee flexor activity were exhibited in all participants; the subject without kinematic improvement had the greatest increase. While the exoskeleton was well tolerated, additional training with a focus on reducing knee flexor activity may lead to further improvements in crouch gait reduction.

Biomechanical effects of robot assisted walking on knee joint kinematics and muscle activation pattern.

Science.gov (United States)

Thangavel, Pavithra; Vidhya, S; Li, Junhua; Chew, Effie; Bezerianos, Anastasios; Yu, Haoyong

2017-07-01

Since manual rehabilitation therapy can be taxing for both the patient and the physiotherapist, a gait rehabilitation robot has been built to reduce the physical strain and increase the efficacy of the rehabilitation therapy. The prototype of the gait rehabilitation robot is designed to provide assistance while walking for patients with abnormal gait pattern and it can also be used for rehabilitation therapy to restore an individual's normal gait pattern by aiding motor recovery. The Gait Rehabilitation Robot uses gait event based synchronization, which enables the exoskeleton to provide synchronous assistance during walking that aims to reduce the lower-limb muscle activation. This study emphasizes on the biomechanical effects of assisted walking on the lower limb by analyzing the EMG signal, knee joint kinematics data that was collected from the right leg during the various experimental conditions. The analysis of the measured data shows an improved knee joint trajectory and reduction in muscle activity with assistance. The result of this study does not only assess the functionality of the exoskeleton but also provides a profound understanding of the human-robot interaction by studying the effects of assistance on the lower limb.

Wave kinematics and response of slender offshore structures. Vol 4: Wave kinematics

Energy Technology Data Exchange (ETDEWEB)

Riber, H.J.

1999-08-01

The kinematics of large surface waves has been measured by means of sonar's placed on the sea floor at the Tyra field. Measurements from the most severe storm are analysed and extreme wave velocity profiles are compared to Stoke wave velocity profiles. Statistical distributions of crest velocity and wave celerity are presented. The analysis shows how the deviation from the Stokes prediction varies with wave heights and steepness. Analyses of the directional wave field leads to the conclusion that the extreme waves are three-dimensional. It is shown that the peculiar kinematics of extreme waves is of great relevance to the design of jacket type structures. (au)

Neck Kinematics and Electromyography While Wearing Head Supported Mass During Running.

Science.gov (United States)

Hanks, Matthew M; Sefton, JoEllen M; Oliver, Gretchen D

2018-01-01

Advanced combat helmets (ACH) coupled with night-vision goggles (NVG) are required for tactical athletes during training and service. Head and neck injuries due to head supported mass (HSM) are a common occurrence in military personnel. The current study aimed to investigate the effects of HSM on neck muscle fatigue that may lead to chronic stress and injury of the head and neck. Subjects wore an ACH and were affixed with electromagnetic sensors to obtain kinematic data, as well as EMG electrodes to obtain muscle activations of bilateral sternocleidomastoid, upper trapezius, and paraspinal muscles while running on a treadmill. Subjects performed a 2-min warmup at a walking pace, a 5-min warmup jog, running at a pace equal to 90% maximum heart rate until absolute fatigue, and lastly a 2-min cooldown at a walking pace. Kinematic and EMG data were collected over each 2-min interval. Days later, the same subjects wore the same ACH in addition to the NVG and performed the same protocol as the first session. This study showed significant differences in muscle activation of the right upper trapezius [F(1,31) = 10.100] and both sternocleidomastoid [F(1,31) = 12.280] muscles from pre-fatigue to absolute fatigue. There were no significant differences noted in the kinematic variables. This study suggests that HSM can fatigue bilateral neck flexors and rotators, as well as fatigue the neck extensors and rotators on the contralateral side of the mounted NVG.Hanks MM, Sefton JM, Oliver GD. Neck kinematics and electromyography while wearing head supported mass during running. Aerosp Med Hum Perform. 2018; 89(1):9-13.

Inverse kinematics of OWI-535 robotic arm

OpenAIRE

DEBENEC, PRIMOŽ

2015-01-01

The thesis aims to calculate the inverse kinematics for the OWI-535 robotic arm. The calculation of the inverse kinematics determines the joint parameters that provide the right pose of the end effector. The pose consists of the position and orientation, however, we will focus only on the second one. Due to arm limitations, we have created our own type of the calculation of the inverse kinematics. At first we have derived it only theoretically, and then we have transferred the derivation into...

Expressions of manipulator kinematic equations via symbolic computation

International Nuclear Information System (INIS)

Sasaki, Shinobu

1993-09-01

While it is simple in principle to determine the position and orientation of the manipulator hand, its computational process has been regarded as extremely laborious since trigonometric functions must be calculated many times in operations of revolute or rotation. Due to development of a general class of kinematic algorithm based on iterative methods, however, we have come to a satisfactory settlement of this problem. In the present article, we consider to construct symbolic kinematic equations in an automatic fashion making use of the algorithm. To this end, recursive expressions are applied to a symbolic computation system REDUCE. As a concrete result, a complete kinematic model for a six-jointed arm having all kinematic attributes is provided. Together with work space analysis, the computer-aided generation of kinematic equations in symbolic form will serve to liberate us from their cumbersome derivations. (author)

2nd Conference on Interdisciplinary Applications in Kinematics

CERN Document Server

Flores, Francisco

2015-01-01

This book collects a number of important contributions presented during the Second Conference on Interdisciplinary Applications of Kinematics (IAK 2013) held in Lima, Peru. The conference brought together scientists from several research fields, such as computational kinematics, multibody systems, industrial machines, robotics, biomechanics, mechatronics, computational chemistry, and vibration analysis, and embraced all key aspects of kinematics, namely, theoretical methods, modeling, optimization, experimental validation, industrial applications, and design. Kinematics is an exciting area of computational mechanics and plays  a central role in a great variety of fields and industrial applications nowadays. Apart from research in pure kinematics, the field deals with problems of practical relevance that need to be solved in an interdisciplinary manner in order for new technologies to develop. The results presented in this book should be of interest for practicing and research engineers as well as Ph.D. stud...

Sensorimotor Reorganizations of Arm Kinematics and Postural Strategy for Functional Whole-Body Reaching Movements in Microgravity

Directory of Open Access Journals (Sweden)

Thomas Macaluso

2017-10-01

Full Text Available Understanding the impact of weightlessness on human behavior during the forthcoming long-term space missions is of critical importance, especially when considering the efficiency of goal-directed movements in these unusual environments. Several studies provided a large set of evidence that gravity is taken into account during the planning stage of arm reaching movements to optimally anticipate its consequence upon the moving limbs. However, less is known about sensorimotor changes required to face weightless environments when individuals have to perform fast and accurate goal-directed actions with whole-body displacement. We thus aimed at characterizing kinematic features of whole-body reaching movements in microgravity, involving high spatiotemporal constraints of execution, to question whether and how humans are able to maintain the performance of a functional behavior in the standards of normogravity execution. Seven participants were asked to reach as fast and as accurately as possible visual targets while standing during microgravity episodes in parabolic flight. Small and large targets were presented either close or far from the participants (requiring, in the latter case, additional whole-body displacement. Results reported that participants successfully performed the reaching task with general temporal features of movement (e.g., movement speed close to land observations. However, our analyses also demonstrated substantial kinematic changes related to the temporal structure of focal movement and the postural strategy to successfully perform -constrained- whole-body reaching movements in microgravity. These immediate reorganizations are likely achieved by rapidly taking into account the absence of gravity in motor preparation and execution (presumably from cues about body limbs unweighting. Specifically, when compared to normogravity, the arm deceleration phase substantially increased. Furthermore, greater whole-body forward displacements

Kinematics/statics analysis of a novel serial-parallel robotic arm with hand

Energy Technology Data Exchange (ETDEWEB)

Lu, Yi; Dai, Zhuohong; Ye, Nijia; Wang, Peng [Yanshan University, Hebei (China)

2015-10-15

A robotic arm with fingered hand generally has multi-functions to complete various complicated operations. A novel serial-parallel robotic arm with a hand is proposed and its kinematics and statics are studied systematically. A 3D prototype of the serial-parallel robotic arm with a hand is constructed and analyzed by simulation. The serial-parallel robotic arm with a hand is composed of an upper 3RPS parallel manipulator, a lower 3SPR parallel manipulator and a hand with three finger mechanisms. Its kinematics formulae for solving the displacement, velocity, acceleration of are derived. Its statics formula for solving the active/constrained forces is derived. Its reachable workspace and orientation workspace are constructed and analyzed. Finally, an analytic example is given for solving the kinematics and statics of the serial-parallel robotic arm with a hand and the analytic solutions are verified by a simulation mechanism.

Kinematics/statics analysis of a novel serial-parallel robotic arm with hand

International Nuclear Information System (INIS)

Lu, Yi; Dai, Zhuohong; Ye, Nijia; Wang, Peng

2015-01-01

A robotic arm with fingered hand generally has multi-functions to complete various complicated operations. A novel serial-parallel robotic arm with a hand is proposed and its kinematics and statics are studied systematically. A 3D prototype of the serial-parallel robotic arm with a hand is constructed and analyzed by simulation. The serial-parallel robotic arm with a hand is composed of an upper 3RPS parallel manipulator, a lower 3SPR parallel manipulator and a hand with three finger mechanisms. Its kinematics formulae for solving the displacement, velocity, acceleration of are derived. Its statics formula for solving the active/constrained forces is derived. Its reachable workspace and orientation workspace are constructed and analyzed. Finally, an analytic example is given for solving the kinematics and statics of the serial-parallel robotic arm with a hand and the analytic solutions are verified by a simulation mechanism.

Kinematic Identification of Parallel Mechanisms by a Divide and Conquer Strategy

DEFF Research Database (Denmark)

Durango, Sebastian; Restrepo, David; Ruiz, Oscar

2010-01-01

using the inverse calibration method. The identification poses are selected optimizing the observability of the kinematic parameters from a Jacobian identification matrix. With respect to traditional identification methods the main advantages of the proposed Divide and Conquer kinematic identification...... strategy are: (i) reduction of the kinematic identification computational costs, (ii) improvement of the numerical efficiency of the kinematic identification algorithm and, (iii) improvement of the kinematic identification results. The contributions of the paper are: (i) The formalization of the inverse...... calibration method as the Divide and Conquer strategy for the kinematic identification of parallel symmetrical mechanisms and, (ii) a new kinematic identification protocol based on the Divide and Conquer strategy. As an application of the proposed kinematic identification protocol the identification...

Using Robotics in Kinematics Classes: Exploring Braking and Stopping Distances

Science.gov (United States)

Brockington, Guilherme; Schivani, Milton; Barscevicius, Cesar; Raquel, Talita; Pietrocola, Maurício

2018-01-01

Research in the field of physics teaching has revealed high school students' difficulties in establishing relations between kinematic equations and real movements. Moreover, there are well-known and significant challenges in their comprehension of graphic language content. Thus, this article explores a didactic activity which utilized robotics in…

Development of Calculation Algorithm for ECCS Kinematic Shock

Energy Technology Data Exchange (ETDEWEB)

Lee, Seung-Chan; Yoon, Duk-Joo; Ha, Sang-Jun [KHNP-CRI, Daejeon (Korea, Republic of)

2014-10-15

The void fraction of inverted U-pipes in front of SI(Safety Injection) pumps impact on the pipe system of ECCS(Emergency Core Cooling Systems). This phenomena is called as 'Kinematic Shock'. The purpose of this paper is to achieve the more exactly calculation when the kinematic shock is calculated by simplified equation. The behavior of the void packet of the ECCS pipes is illustrated by the simplified (other name is kinematic shock equation).. The kinematic shock is defined as the depth of total length of void clusters in the pipes of ECCS when the void cluster is continually reached along the part of pipes in vertical direction. In this paper, the simplified equation is evaluated by comparing calculation error each other.]. The more exact methods of calculating the depth of the kinematic shock in ECCS is achieved. The error of kinematic shock calculation is strongly depended on the calculation search gap and the order of Taylor's expansion. From this study, to select the suitable search gap and the suitable calculation order, differential root method, secant method, and Taylor's expansion form are compared one another.

21st Century Kinematics : The 2012 NSF Workshop

CERN Document Server

2013-01-01

21st Century Kinematics focuses on algebraic problems in the analysis and synthesis of mechanisms and robots, compliant mechanisms, cable-driven systems and protein kinematics. The specialist contributors provide the background for a series of presentations at the 2012 NSF Workshop. The text shows how the analysis and design of innovative mechanical systems yield increasingly complex systems of polynomials, characteristic of those systems. In doing so, takes advantage of increasingly sophisticated computational tools developed for numerical algebraic geometry and demonstrates the now routine derivation of polynomial systems dwarfing the landmark problems of even the recent past. The 21st Century Kinematics workshop echoes the NSF-supported 1963 Yale Mechanisms Teachers Conference that taught a generation of university educators the fundamental principles of kinematic theory. As such these proceedings will be provide admirable supporting theory for a graduate course in modern kinematics and should be of consid...

The Effects of Unilateral Adaptation of Hearing Aids on Symptoms of Depression and Social Activity Constraints of Elderly

Directory of Open Access Journals (Sweden)

Santos, Fernanda Dutra dos

2015-01-01

Full Text Available Introduction Hearing loss is one of the most common problems in the elderly population. Besides compromising oral communication, it directly affects social relations and prevents elderly patients from living actively in society, possibly leading to the onset of depression or other conditions. Objective To analyze the effects of unilateral adaptation of hearing aids on symptoms of depression and the social activity constraints of elderly subjects with hearing impairment. Methods The sample consisted of elderly subjects with hearing loss who did not use hearing aids. Data were collected in two phases. Initially, all participants underwent an audiological assessment and answered the Hearing Handicap Inventory for Elderly (summarized version and the Geriatric Depression Scale. All subjects participated in the selection and hearing aid adaptation processes and became monaural hearing aid users. After 30 days of hearing aid use, they were assessed with the same instruments. The results of the questionnaires before and after hearing aid adaptation were compared. Results The sample consisted of 13 individuals, between 60 and 90 years old (mean 72.85 ± 11.05 years. Data analysis showed that there was significant improvement in social activity constraints (p < 0.001 and in symptoms of depression (p = 0.031. Conclusion Results show that, in the sample studied, unilateral hearing aid adaptation reduced social activity constraints and depression symptoms.

Upper-limb kinematic reconstruction during stroke robot-aided therapy.

Science.gov (United States)

Papaleo, E; Zollo, L; Garcia-Aracil, N; Badesa, F J; Morales, R; Mazzoleni, S; Sterzi, S; Guglielmelli, E

2015-09-01

The paper proposes a novel method for an accurate and unobtrusive reconstruction of the upper-limb kinematics of stroke patients during robot-aided rehabilitation tasks with end-effector machines. The method is based on a robust analytic procedure for inverse kinematics that simply uses, in addition to hand pose data provided by the robot, upper arm acceleration measurements for computing a constraint on elbow position; it is exploited for task space augmentation. The proposed method can enable in-depth comprehension of planning strategy of stroke patients in the joint space and, consequently, allow developing therapies tailored for their residual motor capabilities. The experimental validation has a twofold purpose: (1) a comparative analysis with an optoelectronic motion capturing system is used to assess the method capability to reconstruct joint motion; (2) the application of the method to healthy and stroke subjects during circle-drawing tasks with InMotion2 robot is used to evaluate its efficacy in discriminating stroke from healthy behavior. The experimental results have shown that arm angles are reconstructed with a RMSE of 8.3 × 10(-3) rad. Moreover, the comparison between healthy and stroke subjects has revealed different features in the joint space in terms of mean values and standard deviations, which also allow assessing inter- and intra-subject variability. The findings of this study contribute to the investigation of motor performance in the joint space and Cartesian space of stroke patients undergoing robot-aided therapy, thus allowing: (1) evaluating the outcomes of the therapeutic approach, (2) re-planning the robotic treatment based on patient needs, and (3) understanding pathology-related motor strategies.

Static and kinematic formulation of planar reciprocal assemblies

DEFF Research Database (Denmark)

Parigi, Dario; Sassone, Mario; Kirkegaard, Poul Henning

2014-01-01

Planar reciprocal frames are two dimensional structures formed by elements joined together according to the principle of structural reciprocity. In this paper a rigorous formulation of the static and kinematic problem is proposed and developed extending the theory of pin-jointed assemblies....... This formulation is used to evaluate the static and kinematic determinacy of reciprocal assemblies from the properties of their equilibrium and kinematic matrices...

Kinematics in newly walking toddlers does not depend upon postural stability

NARCIS (Netherlands)

Ivanenko, Yuri P; Dominici, Nadia; Cappellini, Germana; Lacquaniti, Francesco

When a toddler starts to walk without support, gait kinematics and electromyographic (EMG) activity differ from those of older children and the body displays considerable oscillations due to poor equilibrium. Postural instability clearly affects motor patterns in adults, but does instability explain

Discretionary Time of Chinese College Students: Activities and Impact of SARS-Induced Constraints on Choices

Science.gov (United States)

Yang, He; Hutchinson, Susan; Zinn, Harry; Watson, Alan

2011-01-01

How people make choices about activity engagement during discretionary time is a topic of increasing interest to those studying quality of life issues. Assuming choices are made to maximize individual welfare, several factors are believed to influence these choices. Constraints theory from the leisure research literature suggests these choices are…

Kinematic variables and water transport control the formation and location of arc volcanoes.

Science.gov (United States)

Grove, T L; Till, C B; Lev, E; Chatterjee, N; Médard, E

2009-06-04

The processes that give rise to arc magmas at convergent plate margins have long been a subject of scientific research and debate. A consensus has developed that the mantle wedge overlying the subducting slab and fluids and/or melts from the subducting slab itself are involved in the melting process. However, the role of kinematic variables such as slab dip and convergence rate in the formation of arc magmas is still unclear. The depth to the top of the subducting slab beneath volcanic arcs, usually approximately 110 +/- 20 km, was previously thought to be constant among arcs. Recent studies revealed that the depth of intermediate-depth earthquakes underneath volcanic arcs, presumably marking the slab-wedge interface, varies systematically between approximately 60 and 173 km and correlates with slab dip and convergence rate. Water-rich magmas (over 4-6 wt% H(2)O) are found in subduction zones with very different subduction parameters, including those with a shallow-dipping slab (north Japan), or steeply dipping slab (Marianas). Here we propose a simple model to address how kinematic parameters of plate subduction relate to the location of mantle melting at subduction zones. We demonstrate that the location of arc volcanoes is controlled by a combination of conditions: melting in the wedge is induced at the overlap of regions in the wedge that are hotter than the melting curve (solidus) of vapour-saturated peridotite and regions where hydrous minerals both in the wedge and in the subducting slab break down. These two limits for melt generation, when combined with the kinematic parameters of slab dip and convergence rate, provide independent constraints on the thermal structure of the wedge and accurately predict the location of mantle wedge melting and the position of arc volcanoes.

A user friendly method for image based acquisition of constraint information during constrained motion of servo manipulator in hot-cells

International Nuclear Information System (INIS)

Saini, Surendra Singh; Sarkar, Ushnish; Swaroop, Tumapala Teja; Panjikkal, Sreejith; Ray, Debasish Datta

2016-01-01

In master slave manipulator, slave arm is controlled by an operator to manipulate the objects in remote environment using an iso-kinematic master arm which is located in the control room. In such a scenario, where the actual work environment is separated from the operator, formulation of techniques for assisting the operator to execute constrained motion (preferential inclusion or preferential exclusion of workspace zones) in the slave environment are not only helpful, but also essential. We had earlier demonstrated the efficacy of constraint motion with predefined geometrical constraints of various types. However, in a hot-cell scenario the generation of the constraint equations is difficult since we shall not have access to the cell for taking measurements. In this paper, a user friendly method is proposed for image based acquisition of the various constraint geometries thus eliminating the need to take in-cell measurements. For this purpose various hot cell tasks and required geometrical primitives pertaining to these tasks have been surveyed and an algorithm has been developed for generating the constraint geometry for each primitive. This methodology shall increase the efficiency and ease of use of the hot cell Telemanipulator by providing real time constraint acquisition and subsequent assistive force based constrained motion. (author)

Discretionary time of Chinese college students: Activities and impact of SARS-induced constraints on choices

Science.gov (United States)

He Yang; Susan Hutchinson; Harry Zinn; Alan Watson

2011-01-01

How people make choices about activity engagement during discretionary time is a topic of increasing interest to those studying quality of life issues. Assuming choices are made to maximize individual welfare, several factors are believed to influence these choices. Constraints theory from the leisure research literature suggests these choices are heavily influenced by...

Kinematically Decoupled Cores in Dwarf (Elliptical) Galaxies

NARCIS (Netherlands)

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

An overview is given of what we know about the frequency of kinematically decoupled cores in dwarf elliptical galaxies. New observations show that kinematically decoupled cores happen just as often in dwarf elliptical as in ordinary early-type galaxies. This has important consequences for the

Liquidity Constraints and Fiscal Stabilization Policy

DEFF Research Database (Denmark)

Kristoffersen, Mark Strøm

It is often claimed that the presence of liquidity constrained households enhances the need for and the effects of fi…scal stabilization policies. This paper studies this in a model of a small open economy with liquidity constrained households. The results show that the consequences of liquidity...... constraints are more complex than previously thought: The optimal stabilization policy in case of productivity shocks is independent of the liquidity constraints, and the presence of liquidity constraints tends to reduce the need for an active policy stabilizing productivity shocks....

Validation and structural analysis of the kinematics concept test

Directory of Open Access Journals (Sweden)

A. Lichtenberger

2017-04-01

Full Text Available The kinematics concept test (KCT is a multiple-choice test designed to evaluate students’ conceptual understanding of kinematics at the high school level. The test comprises 49 multiple-choice items about velocity and acceleration, which are based on seven kinematic concepts and which make use of three different representations. In the first part of this article we describe the development and the validation process of the KCT. We applied the KCT to 338 Swiss high school students who attended traditional teaching in kinematics. We analyzed the response data to provide the psychometric properties of the test. In the second part we present the results of a structural analysis of the test. An exploratory factor analysis of 664 student answers finally uncovered the seven kinematics concepts as factors. However, the analysis revealed a hierarchical structure of concepts. At the higher level, mathematical concepts group together, and then split up into physics concepts at the lower level. Furthermore, students who seem to understand a concept in one representation have difficulties transferring the concept to similar problems in another representation. Both results have implications for teaching kinematics. First, teaching mathematical concepts beforehand might be beneficial for learning kinematics. Second, instructions have to be designed to teach students the change between different representations.

Validation and structural analysis of the kinematics concept test

Science.gov (United States)

Lichtenberger, A.; Wagner, C.; Hofer, S. I.; Stern, E.; Vaterlaus, A.

2017-06-01

The kinematics concept test (KCT) is a multiple-choice test designed to evaluate students' conceptual understanding of kinematics at the high school level. The test comprises 49 multiple-choice items about velocity and acceleration, which are based on seven kinematic concepts and which make use of three different representations. In the first part of this article we describe the development and the validation process of the KCT. We applied the KCT to 338 Swiss high school students who attended traditional teaching in kinematics. We analyzed the response data to provide the psychometric properties of the test. In the second part we present the results of a structural analysis of the test. An exploratory factor analysis of 664 student answers finally uncovered the seven kinematics concepts as factors. However, the analysis revealed a hierarchical structure of concepts. At the higher level, mathematical concepts group together, and then split up into physics concepts at the lower level. Furthermore, students who seem to understand a concept in one representation have difficulties transferring the concept to similar problems in another representation. Both results have implications for teaching kinematics. First, teaching mathematical concepts beforehand might be beneficial for learning kinematics. Second, instructions have to be designed to teach students the change between different representations.

Validation and Structural Analysis of the Kinematics Concept Test

Science.gov (United States)

Lichtenberger, A.; Wagner, C.; Hofer, S. I.; Stem, E.; Vaterlaus, A.

2017-01-01

The kinematics concept test (KCT) is a multiple-choice test designed to evaluate students' conceptual understanding of kinematics at the high school level. The test comprises 49 multiple-choice items about velocity and acceleration, which are based on seven kinematic concepts and which make use of three different representations. In the first part…

Short-sale Constraints and Credit Runs

DEFF Research Database (Denmark)

Venter, Gyuri

), creditors with high private signals are more lenient to roll over debt, and a bank with lower asset quality remains solvent. This leads to higher allocative efficiency in the real economy. My result thus implies that the decrease in average informativeness due to short-sale constraints can be more than......This paper studies how short-sale constraints affect the informational efficiency of market prices and the link between prices and economic activity. I show that under short-sale constraints security prices contain less information. However, short-sale constraints increase the informativeness...... the price of an asset the bank holds. I show that short-selling constraints in the financial market lead to the revival of self-fulfilling beliefs about the beliefs and actions of others, and create multiple equilibria. In the equilibrium where agents rely more on public information (i.e., the price...

Multibody Kinematics Optimization for the Estimation of Upper and Lower Limb Human Joint Kinematics: A Systematized Methodological Review.

Science.gov (United States)

Begon, Mickaël; Andersen, Michael Skipper; Dumas, Raphaël

2018-03-01

Multibody kinematics optimization (MKO) aims to reduce soft tissue artefact (STA) and is a key step in musculoskeletal modeling. The objective of this review was to identify the numerical methods, their validation and performance for the estimation of the human joint kinematics using MKO. Seventy-four papers were extracted from a systematized search in five databases and cross-referencing. Model-derived kinematics were obtained using either constrained optimization or Kalman filtering to minimize the difference between measured (i.e., by skin markers, electromagnetic or inertial sensors) and model-derived positions and/or orientations. While hinge, universal, and spherical joints prevail, advanced models (e.g., parallel and four-bar mechanisms, elastic joint) have been introduced, mainly for the knee and shoulder joints. Models and methods were evaluated using: (i) simulated data based, however, on oversimplified STA and joint models; (ii) reconstruction residual errors, ranging from 4 mm to 40 mm; (iii) sensitivity analyses which highlighted the effect (up to 36 deg and 12 mm) of model geometrical parameters, joint models, and computational methods; (iv) comparison with other approaches (i.e., single body kinematics optimization and nonoptimized kinematics); (v) repeatability studies that showed low intra- and inter-observer variability; and (vi) validation against ground-truth bone kinematics (with errors between 1 deg and 22 deg for tibiofemoral rotations and between 3 deg and 10 deg for glenohumeral rotations). Moreover, MKO was applied to various movements (e.g., walking, running, arm elevation). Additional validations, especially for the upper limb, should be undertaken and we recommend a more systematic approach for the evaluation of MKO. In addition, further model development, scaling, and personalization methods are required to better estimate the secondary degrees-of-freedom (DoF).

Force generation of bio-inspired hover kinematics

NARCIS (Netherlands)

Vandenheede, R.B.R.; Bernal, L.P.; Morrison, C.L.; Humbert, S.

2012-01-01

This paper presents the results of an experimental study of the aerodynamics of an elliptical flap plate wing in pitch-plunge motion. Several wing motion kinematics are derived from the kinematics of the Agrius Convolvuli (hawk moth) in hover. The experiments are conducted at a Reynolds number of 4,

A Novel Algorithm for the Generation of Distinct Kinematic Chain

Science.gov (United States)

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

2016-07-01

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

Exploring the Origin of Kinematically Irregular Galaxies with MaNGA

Science.gov (United States)

Stark, David Vincent; Bundy, Kevin; Westfall, Kyle; Bershady, Matthew; Cheung, Edmond; Soler, Juan; Brinchmann, Jarle; Abraham, Roberto; Bizyaev, Dmitry; Masters, Karen; Weijmans, Anne-Marie; Chen, Yanmei; Jin, Yifei; Drory, Niv; Lopes, Alexandre Roman; Law, David

2018-01-01

Deviations from normal rotation in galaxies may have a number of potential drivers, including tidal interactions, gas inflows/outflows, spiral structure, bar/oval distortions, or other internally generated instabilities. Thanks to new massive IFU surveys like MaNGA, we can now characterize the gas and stellar kinematics of thousands of galaxies in the local universe, enabling statistical analyses on the frequency of disturbed kinematics, their origin, and their impact on their host galaxies. We present a census of kinematics in MaNGA using a modified version of the Radon transform to map radial variations in kinematic position angles (PA). We discuss the frequency of kinematically irregular disks, and describe commonly observed patterns in radial PA profiles. In order to constrain the drivers of these kinematic signatures, we analyze how they correlate with galaxy mass, environment, star formation history, and gas-phase metallicity.

Evaluation of Handwriting Movement Kinematics: From an Ecological to a Magnetic Resonance Environment

Science.gov (United States)

Bisio, Ambra; Pedullà, Ludovico; Bonzano, Laura; Ruggeri, Piero; Brichetto, Giampaolo; Bove, Marco

2016-01-01

Writing is a means of communication which requires complex motor, perceptual, and cognitive skills. If one of these abilities gets lost following traumatic events or due to neurological diseases, handwriting could deteriorate. Occupational therapy practitioners provide rehabilitation services for people with impaired handwriting. However, to determine the effectiveness of handwriting interventions no studies assessed whether the proposed treatments improved the kinematics of writing movement or had an effect at the level of the central nervous system. There is need to find new quantitative methodologies able to describe the behavioral and the neural outcomes of the rehabilitative interventions for handwriting. In the present study we proposed a combined approach that allowed evaluating the kinematic parameters of handwriting movements, acquired by means of a magnetic resonance-compatible tablet, and their neural correlates obtained simultaneously from a functional magnetic resonance imaging examination. Results showed that the system was reliable in term of reproducibility of the kinematic data during a test/re-test procedure. Further, despite the modifications with respect to an ecological writing movement condition, the kinematic parameters acquired inside the MR-environment were descriptive of individuals’ movement features. At last, the imaging protocol succeeded to show the activation of the cerebral regions associated with the production of writing movement in healthy people. From these findings, this methodology seems to be promising to evaluate the handwriting movement deficits and the potential alterations in the neural activity in those individuals who have handwriting difficulties. Finally, it would provide a mean to quantitatively assess the effect of a rehabilitative treatment. PMID:27746727

Evaluation of handwriting movement kinematics: from an ecological to a magnetic resonance environment

Directory of Open Access Journals (Sweden)

Ambra Bisio

2016-09-01

Full Text Available Writing is a means of communication which requires complex motor, perceptual and cognitive skills. If one of these abilities gets lost following traumatic events or due to neurological diseases, handwriting could deteriorate. Occupational therapy practitioners provide rehabilitation services for people with impaired handwriting. However, to determine the effectiveness of handwriting interventions no studies assessed whether the proposed treatments improved the kinematics of writing movement or had an effect at the level of the central nervous system. There is need to find new quantitative methodologies able to describe the behavioral and the neural outcomes of the rehabilitative interventions for handwriting. In the present study we proposed a combined approach that allowed evaluating the kinematic parameters of handwriting movements, acquired by means of a magnetic resonance-compatible tablet, and their neural correlates obtained simultaneously from a functional magnetic resonance imaging (fMRI examination. Results showed that the system was reliable in term of reproducibility of the kinematic data during a test/re-test procedure. Further, despite the modifications with respect to an ecological writing movement condition, the kinematic parameters acquired inside the MR-environment were descriptive of individuals’ movement features. At last, the imaging protocol succeeded to show the activation of the cerebral regions associated with the production of writing movement in healthy people. From these findings, this methodology seems to be promising to evaluate the handwriting movement deficits and the potential alterations in the neural activity in those individuals who have handwriting difficulties. Finally, it would provide a mean to quantitatively assess the effect of a rehabilitative treatment.

Using robotics in kinematics classes: exploring braking and stopping distances

Science.gov (United States)

Brockington, Guilherme; Schivani, Milton; Barscevicius, Cesar; Raquel, Talita; Pietrocola, Maurício

2018-03-01

Research in the field of physics teaching has revealed high school students’ difficulties in establishing relations between kinematic equations and real movements. Moreover, there are well-known and significant challenges in their comprehension of graphic language content. Thus, this article explores a didactic activity which utilized robotics in order to investigate significant aspects of kinematics, gathering data and performing analyses and descriptions via graphs and mathematical equations which were indispensable for the analysis of the phenomena in question. Traffic safety appears as a main theme, with particular emphasis on the distinction between braking and stopping distances in harsh conditions, as observed in the robot vehicle’s tires and track. This active-learning investigation allows students to identify significant differences between the average value of the initial empirical braking position and that of the vehicle’s programmed braking position, enabling them to more deeply comprehend the relations between mathematical and graphic representations of this real phenomenon and the phenomenon itself, thereby providing a sense of accuracy to this study.

Chiral quark model with relativistic kinematics

International Nuclear Information System (INIS)

Garcilazo, H.; Valcarce, A.

2003-01-01

The nonstrange baryon spectrum is studied within a three-body model that incorporates relativistic kinematics. We found that the combined effect of relativistic kinematics together with the pion exchange between quarks is able to reverse the order of the first positive- and negative-parity nucleon excited states as observed experimentally. Including the chiral partner of the pion (the σ meson) leads to an overall good description of the spectrum

Chiral quark model with relativistic kinematics

OpenAIRE

Garcilazo, H.; Valcarce, A.

2003-01-01

The non-strange baryon spectrum is studied within a three-body model that incorporates relativistic kinematics. We found that the combined effect of relativistic kinematics together with the pion exchange between quarks is able to reverse the order of the first positive- and negative-parity nucleon excited states as observed experimentally. Including the chiral partner of the pion (the $\\sigma$ meson) leads to an overall good description of the spectrum.

A system to measure the kinematics during the entire ski jump sequence using inertial sensors.

Science.gov (United States)

Chardonnens, Julien; Favre, Julien; Cuendet, Florian; Gremion, Gérald; Aminian, Kamiar

2013-01-04

Three-dimensional analysis of the entire sequence in ski jumping is recommended when studying the kinematics or evaluating performance. Camera-based systems which allow three-dimensional kinematics measurement are complex to set-up and require extensive post-processing, usually limiting ski jumping analyses to small numbers of jumps. In this study, a simple method using a wearable inertial sensors-based system is described to measure the orientation of the lower-body segments (sacrum, thighs, shanks) and skis during the entire jump sequence. This new method combines the fusion of inertial signals and biomechanical constraints of ski jumping. Its performance was evaluated in terms of validity and sensitivity to different performances based on 22 athletes monitored during daily training. The validity of the method was assessed by comparing the inclination of the ski and the slope at landing point and reported an error of -0.2±4.8°. The validity was also assessed by comparison of characteristic angles obtained with the proposed system and reference values in the literature; the differences were smaller than 6° for 75% of the angles and smaller than 15° for 90% of the angles. The sensitivity to different performances was evaluated by comparing the angles between two groups of athletes with different jump lengths and by assessing the association between angles and jump lengths. The differences of technique observed between athletes and the associations with jumps length agreed with the literature. In conclusion, these results suggest that this system is a promising tool for a generalization of three-dimensional kinematics analysis in ski jumping. Copyright © 2012 Elsevier Ltd. All rights reserved.

Soft tissue artifact compensation in knee kinematics by multi-body optimization: Performance of subject-specific knee joint models.

Science.gov (United States)

Clément, Julien; Dumas, Raphaël; Hagemeister, Nicola; de Guise, Jaques A

2015-11-05

Soft tissue artifact (STA) distort marker-based knee kinematics measures and make them difficult to use in clinical practice. None of the current methods designed to compensate for STA is suitable, but multi-body optimization (MBO) has demonstrated encouraging results and can be improved. The goal of this study was to develop and validate the performance of knee joint models, with anatomical and subject-specific kinematic constraints, used in MBO to reduce STA errors. Twenty subjects were recruited: 10 healthy and 10 osteoarthritis (OA) subjects. Subject-specific knee joint models were evaluated by comparing dynamic knee kinematics recorded by a motion capture system (KneeKG™) and optimized with MBO to quasi-static knee kinematics measured by a low-dose, upright, biplanar radiographic imaging system (EOS(®)). Errors due to STA ranged from 1.6° to 22.4° for knee rotations and from 0.8 mm to 14.9 mm for knee displacements in healthy and OA subjects. Subject-specific knee joint models were most effective in compensating for STA in terms of abduction-adduction, inter-external rotation and antero-posterior displacement. Root mean square errors with subject-specific knee joint models ranged from 2.2±1.2° to 6.0±3.9° for knee rotations and from 2.4±1.1 mm to 4.3±2.4 mm for knee displacements in healthy and OA subjects, respectively. Our study shows that MBO can be improved with subject-specific knee joint models, and that the quality of the motion capture calibration is critical. Future investigations should focus on more refined knee joint models to reproduce specific OA knee geometry and physiology. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mining Matters : Natural Resource Extraction and Local Business Constraints

NARCIS (Netherlands)

de Haas, Ralph; Poelhekke, Steven

2016-01-01

We estimate the impact of local mining activity on the business constraints experienced by 22,150 firms across eight resource-rich countries. We find that with the presence of active mines, the business environment in the immediate vicinity (<20 km) of a firm deteriorates but business constraints of

A National Study of Constraints to Participation in Outdoor Recreational Activities

Science.gov (United States)

Gary T. Green; J.M. Bowker; X.F. Wang; K. Cordell; Cassandra Y. Johnson

2012-01-01

A number of studies have shown that certain groups in American society (e.g., Blacks, women, urban dwellers) can encounter barriers or perceived constraints to participation in outdoor recreation. Early research on constraints focused on racial or gender differences. More recent research has examined the effects of income, education, age, and place of residence (Arnold...

Plastic frames: Reduction of the kinematical inequality and optimization

International Nuclear Information System (INIS)

Brousse, P.

1979-01-01

It is well-known that the following inequality plays an essential part in the theory of perfectly plastic frames: for all kinematically admissible mechanisms and for bending moments associated with the hinge rotations by the flow rule, the plastic dissipation power is greater than or equal to the load power. This inequality will be termed as the kinematic inequality. It contains parameters generating the mechanisms. In simple cases, several ingenious authors obtained appreciable results excluding parameters. But, in more complicated cases, for instance when the given quantities are not numerical, the parameters remain in the kinematic inequality, thereby precluding exploitation of the kinematic approach. In the present work we overcome this dificulty: we reduce the kinematic inequality, i.e., we replace it by inequalities containing no variable parameter; we then state a process giving automatically such inequalities; finally, we treat a practical application. (orig.)

The Kinematic Learning Model using Video and Interfaces Analysis

Science.gov (United States)

Firdaus, T.; Setiawan, W.; Hamidah, I.

2017-09-01

An educator currently in demand to apply the learning to not be separated from the development of technology. Educators often experience difficulties when explaining kinematics material, this is because kinematics is one of the lessons that often relate the concept to real life. Kinematics is one of the courses of physics that explains the cause of motion of an object, Therefore it takes the thinking skills and analytical skills in understanding these symptoms. Technology is one that can bridge between conceptual relationship with real life. A framework of technology-based learning models has been developed using video and interfaces analysis on kinematics concept. By using this learning model, learners will be better able to understand the concept that is taught by the teacher. This learning model is able to improve the ability of creative thinking, analytical skills, and problem-solving skills on the concept of kinematics.

Kinematic and ground reaction force accommodation during weighted walking.

Science.gov (United States)

James, C Roger; Atkins, Lee T; Yang, Hyung Suk; Dufek, Janet S; Bates, Barry T

2015-12-01

Weighted walking is a functional activity common in daily life and can influence risks for musculoskeletal loading, injury and falling. Much information exists about weighted walking during military, occupational and recreational tasks, but less is known about strategies used to accommodate to weight carriage typical in daily life. The purposes of the study were to examine the effects of weight carriage on kinematics and peak ground reaction force (GRF) during walking, and explore relationships between these variables. Twenty subjects walked on a treadmill while carrying 0, 44.5 and 89 N weights in front of the body. Peak GRF, sagittal plane joint/segment angular kinematics, stride length and center of mass (COM) vertical displacement were measured. Changes in peak GRF and displacement variables between weight conditions represented accommodation. Effects of weight carriage were tested using analysis of variance. Relationships between peak GRF and kinematic accommodation variables were examined using correlation and regression. Subjects were classified into sub-groups based on peak GRF responses and the correlation analysis was repeated. Weight carriage increased peak GRF by an amount greater than the weight carried, decreased stride length, increased vertical COM displacement, and resulted in a more extended and upright posture, with less hip and trunk displacement during weight acceptance. A GRF increase was associated with decreases in hip extension (|r|=.53, p=.020) and thigh anterior rotation (|r|=.57, p=.009) displacements, and an increase in foot anterior rotation displacement (|r|=.58, p=.008). Sub-group analysis revealed that greater GRF increases were associated with changes at multiple sites, while lesser GRF increases were associated with changes in foot and trunk displacement. Weight carriage affected walking kinematics and revealed different accommodation strategies that could have implications for loading and stability. Copyright © 2015 Elsevier B

Constraint Differentiation

DEFF Research Database (Denmark)

Mödersheim, Sebastian Alexander; Basin, David; Viganò, Luca

2010-01-01

We introduce constraint differentiation, a powerful technique for reducing search when model-checking security protocols using constraint-based methods. Constraint differentiation works by eliminating certain kinds of redundancies that arise in the search space when using constraints to represent...... results show that constraint differentiation substantially reduces search and considerably improves the performance of OFMC, enabling its application to a wider class of problems....

Kinematic design considerations for minimally invasive surgical robots: an overview.

Science.gov (United States)

Kuo, Chin-Hsing; Dai, Jian S; Dasgupta, Prokar

2012-06-01

Kinematic design is a predominant phase in the design of robotic manipulators for minimally invasive surgery (MIS). However, an extensive overview of the kinematic design issues for MIS robots is not yet available to both mechanisms and robotics communities. Hundreds of archival reports and articles on robotic systems for MIS are reviewed and studied. In particular, the kinematic design considerations and mechanism development described in the literature for existing robots are focused on. The general kinematic design goals, design requirements, and design preferences for MIS robots are defined. An MIS-specialized mechanism, namely the remote center-of-motion (RCM) mechanism, is revisited and studied. Accordingly, based on the RCM mechanism types, a classification for MIS robots is provided. A comparison between eight different RCM types is given. Finally, several open challenges for the kinematic design of MIS robotic manipulators are discussed. This work provides a detailed survey of the kinematic design of MIS robots, addresses the research opportunity in MIS robots for kinematicians, and clarifies the kinematic point of view to MIS robots as a reference for the medical community. Copyright © 2012 John Wiley & Sons, Ltd.

Kinematic analysis of a posterior-stabilized knee prosthesis.

Science.gov (United States)

Zhao, Zhi-Xin; Wen, Liang; Qu, Tie-Bing; Hou, Li-Li; Xiang, Dong; Bin, Jia

2015-01-20

The goal of total knee arthroplasty (TKA) is to restore knee kinematics. Knee prosthesis design plays a very important role in successful restoration. Here, kinematics models of normal and prosthetic knees were created and validated using previously published data. Computed tomography and magnetic resonance imaging scans of a healthy, anticorrosive female cadaver were used to establish a model of the entire lower limbs, including the femur, tibia, patella, fibula, distal femur cartilage, and medial and lateral menisci, as well as the anterior cruciate, posterior cruciate, medial collateral, and lateral collateral ligaments. The data from the three-dimensional models of the normal knee joint and a posterior-stabilized (PS) knee prosthesis were imported into finite element analysis software to create the final kinematic model of the TKA prosthesis, which was then validated by comparison with a previous study. The displacement of the medial/lateral femur and the internal rotation angle of the tibia were analyzed during 0-135° flexion. Both the output data trends and the measured values derived from the normal knee's kinematics model were very close to the results reported in a previous in vivo study, suggesting that this model can be used for further analyses. The PS knee prosthesis underwent an abnormal forward displacement compared with the normal knee and has insufficient, or insufficiently aggressive, "rollback" compared with the lateral femur of the normal knee. In addition, a certain degree of reverse rotation occurs during flexion of the PS knee prosthesis. There were still several differences between the kinematics of the PS knee prosthesis and a normal knee, suggesting room for improving the design of the PS knee prosthesis. The abnormal kinematics during early flexion shows that the design of the articular surface played a vital role in improving the kinematics of the PS knee prosthesis.

Kinematic Analysis of a Posterior-stabilized Knee Prosthesis

Directory of Open Access Journals (Sweden)

Zhi-Xin Zhao

2015-01-01

Full Text Available Background: The goal of total knee arthroplasty (TKA is to restore knee kinematics. Knee prosthesis design plays a very important role in successful restoration. Here, kinematics models of normal and prosthetic knees were created and validated using previously published data. Methods: Computed tomography and magnetic resonance imaging scans of a healthy, anticorrosive female cadaver were used to establish a model of the entire lower limbs, including the femur, tibia, patella, fibula, distal femur cartilage, and medial and lateral menisci, as well as the anterior cruciate, posterior cruciate, medial collateral, and lateral collateral ligaments. The data from the three-dimensional models of the normal knee joint and a posterior-stabilized (PS knee prosthesis were imported into finite element analysis software to create the final kinematic model of the TKA prosthesis, which was then validated by comparison with a previous study. The displacement of the medial/lateral femur and the internal rotation angle of the tibia were analyzed during 0-135° flexion. Results: Both the output data trends and the measured values derived from the normal knee′s kinematics model were very close to the results reported in a previous in vivo study, suggesting that this model can be used for further analyses. The PS knee prosthesis underwent an abnormal forward displacement compared with the normal knee and has insufficient, or insufficiently aggressive, "rollback" compared with the lateral femur of the normal knee. In addition, a certain degree of reverse rotation occurs during flexion of the PS knee prosthesis. Conclusions: There were still several differences between the kinematics of the PS knee prosthesis and a normal knee, suggesting room for improving the design of the PS knee prosthesis. The abnormal kinematics during early flexion shows that the design of the articular surface played a vital role in improving the kinematics of the PS knee prosthesis.

Kinematic Analysis of a Posterior-stabilized Knee Prosthesis

Science.gov (United States)

Zhao, Zhi-Xin; Wen, Liang; Qu, Tie-Bing; Hou, Li-Li; Xiang, Dong; Bin, Jia

2015-01-01

Background: The goal of total knee arthroplasty (TKA) is to restore knee kinematics. Knee prosthesis design plays a very important role in successful restoration. Here, kinematics models of normal and prosthetic knees were created and validated using previously published data. Methods: Computed tomography and magnetic resonance imaging scans of a healthy, anticorrosive female cadaver were used to establish a model of the entire lower limbs, including the femur, tibia, patella, fibula, distal femur cartilage, and medial and lateral menisci, as well as the anterior cruciate, posterior cruciate, medial collateral, and lateral collateral ligaments. The data from the three-dimensional models of the normal knee joint and a posterior-stabilized (PS) knee prosthesis were imported into finite element analysis software to create the final kinematic model of the TKA prosthesis, which was then validated by comparison with a previous study. The displacement of the medial/lateral femur and the internal rotation angle of the tibia were analyzed during 0–135° flexion. Results: Both the output data trends and the measured values derived from the normal knee's kinematics model were very close to the results reported in a previous in vivo study, suggesting that this model can be used for further analyses. The PS knee prosthesis underwent an abnormal forward displacement compared with the normal knee and has insufficient, or insufficiently aggressive, “rollback” compared with the lateral femur of the normal knee. In addition, a certain degree of reverse rotation occurs during flexion of the PS knee prosthesis. Conclusions: There were still several differences between the kinematics of the PS knee prosthesis and a normal knee, suggesting room for improving the design of the PS knee prosthesis. The abnormal kinematics during early flexion shows that the design of the articular surface played a vital role in improving the kinematics of the PS knee prosthesis. PMID:25591565

Kinematic measures for upper limb robot-assisted therapy following stroke and correlations with clinical outcome measures: A review.

Science.gov (United States)

Tran, Vi Do; Dario, Paolo; Mazzoleni, Stefano

2018-03-01

This review classifies the kinematic measures used to evaluate post-stroke motor impairment following upper limb robot-assisted rehabilitation and investigates their correlations with clinical outcome measures. An online literature search was carried out in PubMed, MEDLINE, Scopus and IEEE-Xplore databases. Kinematic parameters mentioned in the studies included were categorized into the International Classification of Functioning, Disability and Health (ICF) domains. The correlations between these parameters and the clinical scales were summarized. Forty-nine kinematic parameters were identified from 67 articles involving 1750 patients. The most frequently used parameters were: movement speed, movement accuracy, peak speed, number of speed peaks, and movement distance and duration. According to the ICF domains, 44 kinematic parameters were categorized into Body Functions and Structure, 5 into Activities and no parameters were categorized into Participation and Personal and Environmental Factors. Thirteen articles investigated the correlations between kinematic parameters and clinical outcome measures. Some kinematic measures showed a significant correlation coefficient with clinical scores, but most were weak or moderate. The proposed classification of kinematic measures into ICF domains and their correlations with clinical scales could contribute to identifying the most relevant ones for an integrated assessment of upper limb robot-assisted rehabilitation treatments following stroke. Increasing the assessment frequency by means of kinematic parameters could optimize clinical assessment procedures and enhance the effectiveness of rehabilitation treatments. Copyright © 2018 IPEM. Published by Elsevier Ltd. All rights reserved.

Agent Control for Reconfigurable Open Kinematic Chain Manipulators

Directory of Open Access Journals (Sweden)

Janez Sluga

2013-10-01

Full Text Available This paper presents a method for the autonomous control of differently structured open kinematic chains based on multi-agent system technology. The appropriate level of distributing local autonomy (agents to a manipulative structure is defined, which makes it possible to dynamically change the number, type and structure of manipulative components without modifying their behavioural logic. To achieve fast reconfigurable and scalable manipulative systems, a new multi-agent method is developed for controlling the manipulator kinematics. The new method enables independent manipulator structure from the control system because of its structural and system modularity. The proposed method consists of kinematic equations for use in an agent environment, agent motion-planning algorithms, evaluation functions, agent control logic and kinematic algorithms. The results of simulations and real-world experiments demonstrate the usefulness of the approach for different non-redundant and redundant manipulation structures.

The Flipped Classroom and College Physics Students' Motivation and Understanding of Kinematics Graphs

Science.gov (United States)

Cagande, Jeffrey Lloyd L.; Jugar, Richard R.

2018-01-01

Reversing the traditional classroom activities, in the flipped classroom model students view lectures at home and perform activities during class period inside the classroom. This study investigated the effect of a flipped classroom implementation on college physics students' motivation and understanding of kinematics graphs. A Solomon four-group…

Constraint-based scheduling applying constraint programming to scheduling problems

CERN Document Server

Baptiste, Philippe; Nuijten, Wim

2001-01-01

Constraint Programming is a problem-solving paradigm that establishes a clear distinction between two pivotal aspects of a problem: (1) a precise definition of the constraints that define the problem to be solved and (2) the algorithms and heuristics enabling the selection of decisions to solve the problem. It is because of these capabilities that Constraint Programming is increasingly being employed as a problem-solving tool to solve scheduling problems. Hence the development of Constraint-Based Scheduling as a field of study. The aim of this book is to provide an overview of the most widely used Constraint-Based Scheduling techniques. Following the principles of Constraint Programming, the book consists of three distinct parts: The first chapter introduces the basic principles of Constraint Programming and provides a model of the constraints that are the most often encountered in scheduling problems. Chapters 2, 3, 4, and 5 are focused on the propagation of resource constraints, which usually are responsibl...

Change in running kinematics after cycling are related to alterations in running economy in triathletes.

Science.gov (United States)

Bonacci, Jason; Green, Daniel; Saunders, Philo U; Blanch, Peter; Franettovich, Melinda; Chapman, Andrew R; Vicenzino, Bill

2010-07-01

Emerging evidence suggests that cycling may influence neuromuscular control during subsequent running but the relationship between altered neuromuscular control and run performance in triathletes is not well understood. The aim of this study was to determine if a 45 min high-intensity cycle influences lower limb movement and muscle recruitment during running and whether changes in limb movement or muscle recruitment are associated with changes in running economy (RE) after cycling. RE, muscle activity (surface electromyography) and limb movement (sagittal plane kinematics) were compared between a control run (no preceding cycle) and a run performed after a 45 min high-intensity cycle in 15 moderately trained triathletes. Muscle recruitment and kinematics during running after cycling were altered in 7 of 15 (46%) triathletes. Changes in kinematics at the knee and ankle were significantly associated with the change in VO(2) after cycling (precruitment in some triathletes and that changes in kinematics, especially at the ankle, are closely related to alterations in running economy after cycling. Copyright 2010 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Barefoot vs common footwear: A systematic review of the kinematic, kinetic and muscle activity differences during walking.

Science.gov (United States)

Franklin, Simon; Grey, Michael J; Heneghan, Nicola; Bowen, Laura; Li, François-Xavier

2015-09-01

Habitual footwear use has been reported to influence foot structure with an acute exposure being shown to alter foot position and mechanics. The foot is highly specialised thus these changes in structure/position could influence functionality. This review aims to investigate the effect of footwear on gait, specifically focussing on studies that have assessed kinematics, kinetics and muscle activity between walking barefoot and in common footwear. In line with PRISMA and published guidelines, a literature search was completed across six databases comprising Medline, EMBASE, Scopus, AMED, Cochrane Library and Web of Science. Fifteen of 466 articles met the predetermined inclusion criteria and were included in the review. All articles were assessed for methodological quality using a modified assessment tool based on the STROBE statement for reporting observational studies and the CASP appraisal tool. Walking barefoot enables increased forefoot spreading under load and habitual barefoot walkers have anatomically wider feet. Spatial-temporal differences including, reduced step/stride length and increased cadence, are observed when barefoot. Flatter foot placement, increased knee flexion and a reduced peak vertical ground reaction force at initial contact are also reported. Habitual barefoot walkers exhibit lower peak plantar pressures and pressure impulses, whereas peak plantar pressures are increased in the habitually shod wearer walking barefoot. Footwear particularly affects the kinematics and kinetics of gait acutely and chronically. Little research has been completed in older age populations (50+ years) and thus further research is required to better understand the effect of footwear on walking across the lifespan. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Kinematic Analysis of Continuum Robot Consisted of Driven Flexible Rods

Directory of Open Access Journals (Sweden)

Yingzhong Tian

2016-01-01

Full Text Available This paper presents the kinematic analysis of a continuum bionic robot with three flexible actuation rods. Since the motion of the end-effector is actuated by the deformation of the rods, the robot structure is with high elasticity and good compliance and the kinematic analysis of the robot requires special treatment. We propose a kinematic model based on the geometry with constant curvature. The analysis consists of two independent mappings: a general mapping for the kinematics of all robots and a specific mapping for this kind of robots. Both of those mappings are developed for the single section and for the multisections. We aim at providing a guide for kinematic analysis of the similar manipulators through this paper.

Shoulder and Scapular Kinematics during the Windmill Softball Pitch

OpenAIRE

Backus, Sherry I.; Kraszewski, Andrew; Kontaxis, Andreas; Gibbons, Mandi; Bido, Jennifer; Graziano, Jessica; Hafer, Jocelyn; Jones, Kristofer J.; Hillstrom, Howard; Fealy, Stephen

2013-01-01

Objectives: Pitch count has been studied extensively in the overhand throwing athlete. However, pitch count and fatigue have not been systematically evaluated in the female windmill (underhand) throwing athlete. Direct kinematic measurements of the glenohumeral and scapulo-thoracic joint have not to be correlated and determined. The purpose is to measure scapular kinematics for the high school female windmill softball pitcher and identify kinematic adaptions and changes in pitching performanc...

Human grasping database for activities of daily living with depth, color and kinematic data streams.

Science.gov (United States)

Saudabayev, Artur; Rysbek, Zhanibek; Khassenova, Raykhan; Varol, Huseyin Atakan

2018-05-29

This paper presents a grasping database collected from multiple human subjects for activities of daily living in unstructured environments. The main strength of this database is the use of three different sensing modalities: color images from a head-mounted action camera, distance data from a depth sensor on the dominant arm and upper body kinematic data acquired from an inertial motion capture suit. 3826 grasps were identified in the data collected during 9-hours of experiments. The grasps were grouped according to a hierarchical taxonomy into 35 different grasp types. The database contains information related to each grasp and associated sensor data acquired from the three sensor modalities. We also provide our data annotation software written in Matlab as an open-source tool. The size of the database is 172 GB. We believe this database can be used as a stepping stone to develop big data and machine learning techniques for grasping and manipulation with potential applications in rehabilitation robotics and intelligent automation.

Heavy baryon spectroscopy with relativistic kinematics

International Nuclear Information System (INIS)

Valcarce, A.; Garcilazo, H.; Vijande, J.

2014-01-01

We present a comparative Faddeev study of heavy baryon spectroscopy with nonrelativistic and relativistic kinematics. We show results for different standard hyperfine interactions with both kinematics in an attempt to learn about the light quark dynamics. We highlight the properties of particular states accessible in nowadays laboratories that would help in discriminating between different dynamical models. The advance in the knowledge of light quark dynamics is a key tool for the understanding of the existence of exotic hadrons.

Kinematic and neuromuscular relationships between lower extremity clinical movement assessments.

Science.gov (United States)

Mauntel, Timothy C; Cram, Tyler R; Frank, Barnett S; Begalle, Rebecca L; Norcross, Marc F; Blackburn, J Troy; Padua, Darin A

2018-06-01

Lower extremity injuries have immediate and long-term consequences. Lower extremity movement assessments can assist with identifying individuals at greater injury risk and guide injury prevention interventions. Movement assessments identify similar movement characteristics and evidence suggests large magnitude kinematic relationships exist between movement patterns observed across assessments; however, the magnitude of the relationships for electromyographic (EMG) measures across movement assessments remains largely unknown. This study examined relationships between lower extremity kinematic and EMG measures during jump landings and single leg squats. Lower extremity three-dimensional kinematic and EMG data were sampled from healthy adults (males = 20, females = 20) during the movement assessments. Pearson correlations examined the relationships of the kinematic and EMG measures and paired samples t-tests compared mean kinematic and EMG measures between the assessments. Overall, significant moderate correlations were observed for lower extremity kinematic (r avg  = 0.41, r range  = 0.10-0.61) and EMG (r avg  = 0.47, r range  = 0.32-0.80) measures across assessments. Kinematic and EMG measures were greater during the jump landings. Jump landings and single leg squats place different demands on the body and necessitate different kinematic and EMG patterns, such that these measures are not highly correlated between assessments. Clinicians should, therefore, use multiple assessments to identify aberrant movement and neuromuscular control patterns so that comprehensive interventions can be implemented.

Inverse kinematics of a dual linear actuator pitch/roll heliostat

Science.gov (United States)

Freeman, Joshua; Shankar, Balakrishnan; Sundaram, Ganesh

2017-06-01

This work presents a simple, computationally efficient inverse kinematics solution for a pitch/roll heliostat using two linear actuators. The heliostat design and kinematics have been developed, modeled and tested using computer simulation software. A physical heliostat prototype was fabricated to validate the theoretical computations and data. Pitch/roll heliostats have numerous advantages including reduced cost potential and reduced space requirements, with a primary disadvantage being the significantly more complicated kinematics, which are solved here. Novel methods are applied to simplify the inverse kinematics problem which could be applied to other similar problems.

Understanding the leisure constraints of Hispanic-Americans in Northern Virginia: an exploratory analysis of constraints, socioeconomic status and acculturation

Science.gov (United States)

Edward F, II Byrne; Ellen B. Drogin Rodgers

2003-01-01

The purpose of this study is to investigate the constraints to use of outdoor recreation resources and participation in leisure activities among Hispanic restaurant workers in Northern Virginia; specifically, the relationship of socioeconomic status and acculturation to leisure constraints. The dramatic rate of increase of Hispanic-Americans, the group's low...

Interactive cervical motion kinematics: sensitivity, specificity and clinically significant values for identifying kinematic impairments in patients with chronic neck pain.

Science.gov (United States)

Sarig Bahat, Hilla; Chen, Xiaoqi; Reznik, David; Kodesh, Einat; Treleaven, Julia

2015-04-01

Chronic neck pain has been consistently shown to be associated with impaired kinematic control including reduced range, velocity and smoothness of cervical motion, that seem relevant to daily function as in quick neck motion in response to surrounding stimuli. The objectives of this study were: to compare interactive cervical kinematics in patients with neck pain and controls; to explore the new measures of cervical motion accuracy; and to find the sensitivity, specificity, and optimal cutoff values for defining impaired kinematics in those with neck pain. In this cross-section study, 33 patients with chronic neck pain and 22 asymptomatic controls were assessed for their cervical kinematic control using interactive virtual reality hardware and customized software utilizing a head mounted display with built-in head tracking. Outcome measures included peak and mean velocity, smoothness (represented by number of velocity peaks (NVP)), symmetry (represented by time to peak velocity percentage (TTPP)), and accuracy of cervical motion. Results demonstrated significant and strong effect-size differences in peak and mean velocities, NVP and TTPP in all directions excluding TTPP in left rotation, and good effect-size group differences in 5/8 accuracy measures. Regression results emphasized the high clinical value of neck motion velocity, with very high sensitivity and specificity (85%-100%), followed by motion smoothness, symmetry and accuracy. These finding suggest cervical kinematics should be evaluated clinically, and screened by the provided cut off values for identification of relevant impairments in those with neck pain. Such identification of presence or absence of kinematic impairments may direct treatment strategies and additional evaluation when needed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Monitoring diver kinematics with dielectric elastomer sensors

Science.gov (United States)

Walker, Christopher R.; Anderson, Iain A.

2017-04-01

Diving, initially motivated for food purposes, is crucial to the oil and gas industry, search and rescue, and is even done recreationally by millions of people. There is a growing need however, to monitor the health and activity of divers. The Divers Alert Network has reported on average 90 fatalities per year since 1980. Furthermore an estimated 1000 divers require recompression treatment for dive-related injuries every year. One means of monitoring diver activity is to integrate strain sensors into a wetsuit. This would provide kinematic information on the diver potentially improving buoyancy control assessment, providing a platform for gesture communication, detecting panic attacks and monitoring diver fatigue. To explore diver kinematic monitoring we have coupled dielectric elastomer sensors to a wetsuit worn by the pilot of a human-powered wet submarine. This provided a unique platform to test the performance and accuracy of dielectric elastomer strain sensors in an underwater application. The aim of this study was to assess the ability of strain sensors to monitor the kinematics of a diver. This study was in collaboration with the University of Auckland's human-powered submarine team, Team Taniwha. The pilot, completely encapsulated in a hull, pedals to propel the submarine forward. Therefore this study focused on leg motion as that is the primary motion of the submarine pilot. Four carbon-filled silicone dielectric elastomer sensors were fabricated and coupled to the pilot's wetsuit. The first two sensors were attached over the knee joints, with the remaining two attached between the pelvis and thigh. The goal was to accurately measure leg joint angles thereby determining the position of each leg relative to the hip. A floating data acquisition unit monitored the sensors and transmitted data packets to a nearby computer for real-time processing. A GoPro Hero 4 silver edition was used to capture the experiments and provide a means of post-validation. The

Kinematic Hardening: Characterization, Modeling and Impact on Springback Prediction

International Nuclear Information System (INIS)

Alves, J. L.; Bouvier, S.; Jomaa, M.; Billardon, R.; Oliveira, M. C.; Menezes, L. F.

2007-01-01

The constitutive modeling of the materials' mechanical behavior, usually carried out using a phenomenological constitutive model, i.e., a yield criterion associated to the isotropic and kinematic hardening laws, is of paramount importance in the FEM simulation of the sheet metal forming processes, as well as in the springback prediction. Among others, the kinematic behavior of the yield surface plays an essential role, since it is indispensable to describe the Bauschinger effect, i.e., the materials' answer to the multiple tension-compression cycles to which material points are submitted during the forming process. Several laws are usually used to model and describe the kinematic hardening, namely: a) the Prager's law, which describes a linear evolution of the kinematic hardening with the plastic strain rate tensor b) the Frederick-Armstrong non-linear kinematic hardening, basically a non-linear law with saturation; and c) a more advanced physically-based law, similar to the previous one but sensitive to the strain path changes. In the present paper a mixed kinematic hardening law (linear + non-linear behavior) is proposed and its implementation into a static fully-implicit FE code is described. The material parameters identification for sheet metals using different strategies, and the classical Bauschinger loading tests (i.e. in-plane forward and reverse monotonic loading), are addressed, and their impact on springback prediction evaluated. Some numerical results concerning the springback prediction of the Numisheet'05 Benchmark no. 3 are briefly presented to emphasize the importance of a correct modeling and identification of the kinematic hardening behavior

DIDACTIC AUTOMATED STATION OF COMPLEX KINEMATICS

Directory of Open Access Journals (Sweden)

Mariusz Sosnowski

2014-03-01

Full Text Available The paper presents the design, control system and software that controls the automated station of complex kinematics. Control interface and software has been developed and manufactured in the West Pomeranian University of Technology in Szczecin in the Department of Automated Manufacturing Systems Engineering and Quality. Conducting classes designed to teach programming and design of structures and systems for monitoring the robot kinematic components with non-standard structures was the reason for installation of the control system and software.

Kinematical coincidence method in transfer reactions

Energy Technology Data Exchange (ETDEWEB)

Acosta, L.; Amorini, F. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Auditore, L. [INFN Gruppo Collegato di Messina and Dipartimento di Fisica, Università di Messina (Italy); Berceanu, I. [Institute for Physics and Nuclear Engineering, Bucharest (Romania); Cardella, G., E-mail: cardella@ct.infn.it [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Chatterjiee, M.B. [Saha Institute for Nuclear Physics, Kolkata (India); De Filippo, E. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Francalanza, L.; Gianì, R. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia, Catania (Italy); Grassi, L. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Rudjer Boskovic Institute, Zagreb (Croatia); Grzeszczuk, A. [Institut of Physics, University of Silesia, Katowice (Poland); La Guidara, E. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Centro Siciliano di Fisica Nucleare e Struttura della Materia, Catania (Italy); Lanzalone, G. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Facoltà di Ingegneria e Architettura, Università Kore, Enna (Italy); Lombardo, I. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Scienze Fisiche, Università Federico II and INFN Sezione di Napoli (Italy); Loria, D.; Minniti, T. [INFN Gruppo Collegato di Messina and Dipartimento di Fisica, Università di Messina (Italy); Pagano, E.V. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia, Catania (Italy); and others

2013-07-01

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 {sup 10}Be+p→{sup 9}Be+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.

An adaptive inverse kinematics algorithm for robot manipulators

Science.gov (United States)

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

1990-01-01

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

Kinematic top analyses at CDF

Energy Technology Data Exchange (ETDEWEB)

Grassmann, H.; CDF Collaboration

1995-03-01

We present an update of the top quark analysis using kinematic techniques in p{bar p} collisions at {radical}s = 1.8 TeV with the Collider Detector at Fermilab (CDF). We reported before on a study which used 19.3 pb{sup {minus}1} of data from the 1992--1993 collider run, but now we use a larger data sample of 67 pb{sup {minus}1}. First, we analyze the total transverse energy of the hard collision in W+{ge}3 jet events, showing the likely presence of a t{bar t} component in the event sample. Next, we compare in more detail the kinematic structure of W+ {ge}3 jet events with expectations for top pair production and with background processes, predominantly direct W+ jet production. We again find W+ {ge} 3 jet events which cannot be explained in terms of background, but show kinematic features as expected from top. These events also show evidence for beauty quarks, in agreement with expectations from top, but not compatible with expectations from backgrounds. The findings confirm the observation of top events made earlier in the data of the 1992--1993 collider run.

Latest Advances in Robot Kinematics

CERN Document Server

Husty, Manfred

2012-01-01

This book is  of interest to researchers inquiring about modern topics and methods in the kinematics, control and design of robotic manipulators. It considers the full range of robotic systems, including serial, parallel and cable driven manipulators, both planar and spatial. The systems range from being less than fully mobile to kinematically redundant to overconstrained. In addition to recognized areas, this book also presents recent advances in emerging areas such as the design and control of humanoids and humanoid subsystems, and the analysis, modeling and simulation of human body motions, as well as the mobility analysis of protein molecules and the development of machines which incorporate man.

Kinematic sensitivity of robot manipulators

Science.gov (United States)

Vuskovic, Marko I.

1989-01-01

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.

Stabilization Methods for the Integration of DAE in the Presence of Redundant Constraints

International Nuclear Information System (INIS)

Neto, Maria Augusta; Ambrosio, Jorge

2003-01-01

The use of multibody formulations based on Cartesian or natural coordinates lead to sets of differential-algebraic equations that have to be solved. The difficulty in providing compatible initial positions and velocities for a general spatial multibody model and the finite precision of such data result in initial errors that must be corrected during the forward dynamic solution of the system equations of motion.As the position and velocity constraint equations are not explicitly involved in the solution procedure, any integration error leads to the violation of these equations in the long run. Another problem that is very often impossible to avoid is the presence of redundant constraints.Even with no initial redundancy it is possible for some systems to achieve singular configurations in which kinematic constraints become temporarily redundant. In this work several procedures to stabilize the solution of the equations of motion and to handle redundant constraints are revisited. The Baumgarte stabilization, augmented Lagrangian and coordinate partitioning methods are discussed in terms of their efficiency and computational costs. The LU factorization with full pivoting of the Jacobian matrix directs the choice of the set of independent coordinates, required by the coordinate partitioning method.Even when no particular stabilization method is used, a Newton-Raphson iterative procedure is still required in the initial time step to correct the initial positions and velocities, thus requiring the selection of the independent coordinates. However, this initial selection does not guarantee that during the motion of the system other constraints do not become redundant. Two procedures based on the single value decomposition and Gram-Schmidt orthogonalization are revisited for the purpose. The advantages and drawbacks of the different procedures,used separately or in conjunction with each other and their computational costs are finally discussed

Color-Kinematics Duality for QCD Amplitudes

CERN Document Server

Johansson, Henrik

2016-01-01

We show that color-kinematics duality is present in tree-level amplitudes of quantum chromodynamics with massive flavored quarks. Starting with the color structure of QCD, we work out a new color decomposition for n-point tree amplitudes in a reduced basis of primitive amplitudes. These primitives, with k quark-antiquark pairs and (n-2k) gluons, are taken in the (n-2)!/k! Melia basis, and are independent under the color-algebra Kleiss-Kuijf relations. This generalizes the color decomposition of Del Duca, Dixon, and Maltoni to an arbitrary number of quarks. The color coefficients in the new decomposition are given by compact expressions valid for arbitrary gauge group and representation. Considering the kinematic structure, we show through explicit calculations that color-kinematics duality holds for amplitudes with general configurations of gluons and massive quarks. The new (massive) amplitude relations that follow from the duality can be mapped to a well-defined subset of the familiar BCJ relations for gluo...

Coordinate transformations, orthographic projections, and robot kinematics

International Nuclear Information System (INIS)

Crochetiere, W.J.

1984-01-01

Humans do not consciously think of moving each of their joints while they move their hands from one place to another. Likewise, robot arms can be commanded to move about in cartesian space without the need to address the individual joints. To do this, the direct and inverse kinematic equations of any robot arm must be derived. The direct kinematic equations uniquely transform the joint positions into the position (and orientation) of the hand, whereas the inverse kinematic equations transform the position (and orientation) of the hand into joint positions. The derivation of the inverse kinematic equations for any particular robot is a difficult problem which may have more than one solution. In this paper, these equations are derived for a six degree of freedom robot arm. A combination of matrix operations to perform coordinate rotations, and trigonometry within the appropriate orthographic projects to perform coordinate translations is employed. This complementary approach yields a solution which is more easily obtained, and also more easily visualized. The resulting solution was programmed into a real-time computer as a part of a higher level software system to control the motion of the arm

The kinematic algebras from the scattering equations

International Nuclear Information System (INIS)

Monteiro, Ricardo; O’Connell, Donal

2014-01-01

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

Movement coordination and differential kinematics of the cervical and thoracic spines in people with chronic neck pain.

Science.gov (United States)

Tsang, Sharon M H; Szeto, Grace P Y; Lee, Raymond Y W

2013-07-01

Research on the kinematics and inter-regional coordination of movements between the cervical and thoracic spines in motion adds to our understanding of the performance and interplay of these spinal regions. The purpose of this study was to examine the effects of chronic neck pain on the three-dimensional kinematics and coordination of the cervical and thoracic spines during active movements of the neck. Three-dimensional spinal kinematics and movement coordination between the cervical, upper thoracic, and lower thoracic spines were examined by electromagnetic motion sensors in thirty-four individuals with chronic neck pain and thirty-four age- and gender-matched asymptomatic subjects. All subjects performed a set of free active neck movements in three anatomical planes in sitting position and at their own pace. Spinal kinematic variables (angular displacement, velocity, and acceleration) of the three defined regions, and movement coordination between regions were determined and compared between the two groups. Subjects with chronic neck pain exhibited significantly decreased cervical angular velocity and acceleration of neck movement. Cross-correlation analysis revealed consistently lower degrees of coordination between the cervical and upper thoracic spines in the neck pain group. The loss of coordination was most apparent in angular velocity and acceleration of the spine. Assessment of the range of motion of the neck is not sufficient to reveal movement dysfunctions in chronic neck pain subjects. Evaluation of angular velocity and acceleration and movement coordination should be included to help develop clinical intervention strategies to promote restoration of differential kinematics and movement coordination. Copyright © 2013 Elsevier Ltd. All rights reserved.

Motor resonance facilitates movement execution: an ERP and kinematic study

Directory of Open Access Journals (Sweden)

Mathilde eMénoret

2013-10-01

Full Text Available Action observation, simulation and execution share neural mechanisms that allow for a common motor representation. It is known that when these overlapping mechanisms are simultaneously activated by action observation and execution, motor performance is influenced by observation and vice versa. To understand the neural dynamics underlying this influence and to measure how variations in brain activity impact the precise kinematics of motor behaviour, we coupled kinematics and electrophysiological recordings of participants while they performed and observed congruent or non-congruent actions or during action execution alone. We found that movement velocities and the trajectory deviations of the executed actions increased during the observation of congruent actions compared to the observation of non-congruent actions or action execution alone. This facilitation was also discernible in the motor-related potentials of the participants; the motor-related potentials were transiently more negative in the congruent condition around the onset of the executed movement, which occurred 300 ms after the onset of the observed movement. This facilitation seemed to depend not only on spatial congruency but also on the optimal temporal relationship of the observation and execution events.

Development and validation of a computational model to study the effect of foot constraint on ankle injury due to external rotation.

Science.gov (United States)

Wei, Feng; Hunley, Stanley C; Powell, John W; Haut, Roger C

2011-02-01

Recent studies, using two different manners of foot constraint, potted and taped, document altered failure characteristics in the human cadaver ankle under controlled external rotation of the foot. The posterior talofibular ligament (PTaFL) was commonly injured when the foot was constrained in potting material, while the frequency of deltoid ligament injury was higher for the taped foot. In this study an existing multibody computational modeling approach was validated to include the influence of foot constraint, determine the kinematics of the joint under external foot rotation, and consequently obtain strains in various ligaments. It was hypothesized that the location of ankle injury due to excessive levels of external foot rotation is a function of foot constraint. The results from this model simulation supported this hypothesis and helped to explain the mechanisms of injury in the cadaver experiments. An excessive external foot rotation might generate a PTaFL injury for a rigid foot constraint, and an anterior deltoid ligament injury for a pliant foot constraint. The computational models may be further developed and modified to simulate the human response for different shoe designs, as well as on various athletic shoe-surface interfaces, so as to provide a computational basis for optimizing athletic performance with minimal injury risk.

Estimation of kinematic parameters in CALIFA galaxies: no-assumption on internal dynamics

Science.gov (United States)

García-Lorenzo, B.; Barrera-Ballesteros, J.; CALIFA Team

2016-06-01

We propose a simple approach to homogeneously estimate kinematic parameters of a broad variety of galaxies (elliptical, spirals, irregulars or interacting systems). This methodology avoids the use of any kinematical model or any assumption on internal dynamics. This simple but novel approach allows us to determine: the frequency of kinematic distortions, systemic velocity, kinematic center, and kinematic position angles which are directly measured from the two dimensional-distributions of radial velocities. We test our analysis tools using the CALIFA Survey

Kinematic seismic response of piles in layered soil profile

International Nuclear Information System (INIS)

Ahmad, I.; Khan, A.N.

2006-01-01

This paper is aimed at highlighting the importance of Kinematic Seismic Response of Piles, a phenomenon often ignored in dynamic analysis. A case study is presented where the end bearing pile is embedded in two layer soil system of highly contrasting stiffnesses; a typical case where kinematic loading plays important role. The pile soil system is modeled as continuous system and as discrete parameter system; both are based on BDWF (Beam on Dynamic Winkler Foundation) formulation. For discrete parameter system, a finite element software SAP2000 is used and the modeling technique of kinematic interaction in finite element software is discussed. For pile soil system modeled as continuous system, a general MATLAB code is developed capable of performing elastic site response analysis in two layer soil system, solving differential equation governing kinematic interaction, and giving as output the maximum ground displacement, maximum pile displacement, rotation, moment and shear distribution along pile length. The paper concludes that kinematic seismic actions must be evaluated particularly at the interface of soil layers of significantly differing soil stiffnesses. (author)

Inverse Kinematics of a Serial Robot

Directory of Open Access Journals (Sweden)

Amici Cinzia

2016-01-01

Full Text Available This work describes a technique to treat the inverse kinematics of a serial manipulator. The inverse kinematics is obtained through the numerical inversion of the Jacobian matrix, that represents the equation of motion of the manipulator. The inversion is affected by numerical errors and, in different conditions, due to the numerical nature of the solver, it does not converge to a reasonable solution. Thus a soft computing approach is adopted to mix different traditional methods to obtain an increment of algorithmic convergence.

The impact of galaxy formation on satellite kinematics and redshift-space distortions

Science.gov (United States)

Orsi, Álvaro A.; Angulo, Raúl E.

2018-04-01

Galaxy surveys aim to map the large-scale structure of the Universe and use redshift-space distortions to constrain deviations from general relativity and probe the existence of massive neutrinos. However, the amount of information that can be extracted is limited by the accuracy of theoretical models used to analyse the data. Here, by using the L-Galaxies semi-analytical model run over the Millennium-XXL N-body simulation, we assess the impact of galaxy formation on satellite kinematics and the theoretical modelling of redshift-space distortions. We show that different galaxy selection criteria lead to noticeable differences in the radial distributions and velocity structure of satellite galaxies. Specifically, whereas samples of stellar mass selected galaxies feature satellites that roughly follow the dark matter, emission line satellite galaxies are located preferentially in the outskirts of haloes and display net infall velocities. We demonstrate that capturing these differences is crucial for modelling the multipoles of the correlation function in redshift space, even on large scales. In particular, we show how modelling small-scale velocities with a single Gaussian distribution leads to a poor description of the measured clustering. In contrast, we propose a parametrization that is flexible enough to model the satellite kinematics and that leads to an accurate description of the correlation function down to sub-Mpc scales. We anticipate that our model will be a necessary ingredient in improved theoretical descriptions of redshift-space distortions, which together could result in significantly tighter cosmological constraints and a more optimal exploitation of future large data sets.

Constraint-Referenced Analytics of Algebra Learning

Science.gov (United States)

Sutherland, Scot M.; White, Tobin F.

2016-01-01

The development of the constraint-referenced analytics tool for monitoring algebra learning activities presented here came from the desire to firstly, take a more quantitative look at student responses in collaborative algebra activities, and secondly, to situate those activities in a more traditional introductory algebra setting focusing on…

Teaching about Kinematics

Science.gov (United States)

Nelson, Jane Bray; Nelson, Jim

2009-01-01

Written by Jim and Jane Nelson, Teaching About Kinematics is the latest AAPT/PTRA resource book. Based on physics education research, the book provides teachers with the resources needed to introduce students to some of the fundamental building blocks of physics. It is a carefully thought-out, step-by-step laboratory-based introduction to the…

Kinematic cross-correlation induces sensory integration across separate objects.

Science.gov (United States)

Debats, Nienke B; Ernst, Marc O; Heuer, Herbert

2017-12-01

In a basic cursor-control task, the perceived positions of the hand and the cursor are biased towards each other. We recently found that this phenomenon conforms to the reliability-based weighting mechanism of optimal multisensory integration. This indicates that optimal integration is not restricted to sensory signals originating from a single source, as is the prevailing view, but that it also applies to separate objects that are connected by a kinematic relation (i.e. hand and cursor). In the current study, we examined which aspects of the kinematic relation are crucial for eliciting the sensory integration: (i) the cross-correlation between kinematic variables of the hand and cursor trajectories, and/or (ii) an internal model of the hand-cursor kinematic transformation. Participants made out-and-back movements from the centre of a semicircular workspace to its boundary, after which they judged the position where either their hand or the cursor hit the boundary. We analysed the position biases and found that the integration was strong in a condition with high kinematic correlations (a straight hand trajectory was mapped to a straight cursor trajectory), that it was significantly reduced for reduced kinematic correlations (a straight hand trajectory was transformed into a curved cursor trajectory) and that it was not affected by the inability to acquire an internal model of the kinematic transformation (i.e. by the trial-to-trial variability of the cursor curvature). These findings support the idea that correlations play a crucial role in multisensory integration irrespective of the number of sensory sources involved. © 2017 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Kinematic variables of table vault on artistic gymnastics

Directory of Open Access Journals (Sweden)

Sarah Maria Boldrini FERNANDES

2016-03-01

Full Text Available Abstract The table vault is an event of male and female Artistics Gymnastics. Although it can be performed in a variety of rotations and body positions in different phases, it can be separated in three groups: handspring, Yurchenko and Tsukahara. It is believed that kinematic variables of vault may vary according to group of vault or gymnast body position, but few studies compares the real differences among the three groups of vaults, comparing and describing the variables in different phases. Vault kinematic variables could be diversifying according to the approach or position of the vaulting, but little has been studied about the biomechanical differences, comparing and describing behaviours at different stages. The aim of this study was to organize critical, objective and to systematize the most relevant kinematic variables to performance on vaulting. A Meta analysis over the basis Pubmed, Sport Discus and Web of Science were performed about this issue. From the selected references, we described and analyzed the kinematics of the table vault. Vault can be characterized in seven phases of analysis. Most of the studies are descriptive, and some do not descript all phases. Differences among vault variables according to group vaults, technical level and gender were analysed only in recent studies. There still gaps of knowledge about kinematic variables of table vault, in order to provide comprehensive information about all possibilities of vaults in this gymnastic event. It is concluded that kinematic variables of table vault depends upon vault group and may be considered to the improvement of technical performance. More researches are needed to approach the coaching interface with biomechanics applicable knowledge.

Influence of gravity compensation on kinematics and muscle activation patterns during reach and retrieval in subjects with cervical spinal cord injury: An explorative study

OpenAIRE

Marieke G . M. Kloosterman, PT, MSc; Govert J. Snoek, MD, PhD; Mirjam Kouwenhoven, MD; Anand V. Nene, MD, PhD; Michiel J. A. Jannink, PhD

2010-01-01

Many interventions in upper-limb rehabilitation after cervical spinal cord injury (CSCI) use arm support (gravity compensation); however, its specific effects on kinematics and muscle activation characteristics in subjects with a CSCI are largely unknown. We conducted a cross-sectional explorative study to study these effects. Nine subjects with a CSCI performed two goal-directed arm movements (maximal reach, reach and retrieval) with and without gravity compensation. Angles at elbow and shou...

Lepton number violation at colliders from kinematically inaccessible gauge bosons

Energy Technology Data Exchange (ETDEWEB)

Ruiz, Richard [Durham University, Department of Physics, Institute for Particle Physics Phenomenology (IPPP), Durham (United Kingdom); DARC, Durham (United Kingdom)

2017-06-15

We reevaluate the necessity of W{sub R} gauge bosons being kinematically accessible to test the left-right symmetric model (LRSM) at hadron colliders. In the limit that W{sub R} are too heavy, resonant production of sub-TeV Majorana neutrinos N can still proceed at the Large Hadron Collider (LHC) via the process pp → W{sub R}{sup ±*} → Nl{sup ±} → l{sup ±}l{sup ±} + nj if mediated by a far off-shell W{sub R}. Traditional searches strategies are insensitive to this regime as they rely on momenta of final states scaling with TeV-scale M{sub W{sub R}}. For such situations, the process is actually kinematically and topologically identical to the direct production (DP) process pp → W{sub SM}{sup ±*} → Nl{sup ±} → l{sup ±}l{sup ±} + nj. In this context, we reinterpret √(s) = 8 TeV LHC constraints on DP rates for the minimal LRSM. For m{sub N} = 200-500 GeV and right-left coupling ratio κ{sub R} = g{sub R}/g{sub L}, we find (M{sub W{sub R}}/κ{sub R}) > 1.1-1.8 TeV at 95% CLs. Expected sensitivities to DP at 14 (100) TeV are also recast: with L = 1 (10) ab{sup -1}, one can probe (M{sub W{sub R}}/κ{sub R}) < 7.9-8.9 (14-40) TeV for m{sub N} = 100-700 (1200) GeV, well beyond the anticipated sensitivity of resonant W{sub R} searches. Findings in terms of gauge invariant dimension-six operators with heavy N are also reported. (orig.)

H I Kinematics along the Minor Axis of M82

Science.gov (United States)

Martini, Paul; Leroy, Adam K.; Mangum, Jeffrey G.; Bolatto, Alberto; Keating, Katie M.; Sandstrom, Karin; Walter, Fabian

2018-03-01

M82 is one of the best-studied starburst galaxies in the local universe, and is consequently a benchmark for studying star formation feedback at both low and high redshift. We present new VLA H I observations that reveal the cold gas kinematics along the minor axis in unprecedented detail. This includes the detection of H I up to 10 kpc along the minor axis toward the south and beyond 5 kpc to the north. A surprising aspect of these observations is that the line-of-sight H I velocity decreases substantially from about 120 to 50 {km} {{{s}}}-1 from 1.5 to 10 kpc off the midplane. The velocity profile is not consistent with the H I gas cooling from the hot wind. We demonstrate that the velocity decrease is substantially greater than the deceleration expected from gravitational forces alone. If the H I consists of a continuous population of cold clouds, some additional drag force must be present, and the magnitude of the drag force places a joint constraint on the ratio of the ambient medium to the typical cloud size and density. We also show that the H I kinematics are inconsistent with a simple conical outflow centered on the nucleus, but instead require the more widespread launch of the H I over the ∼1 kpc extent of the starburst region. Regardless of the launch mechanism for the H I gas, the observed velocity decrease along the minor axis is sufficiently great that the H I may not escape the halo of M82. The inferred H I outflow rate at 10 kpc off the midplane is much less than 1 {M}ȯ yr‑1.

Diagnosing the Kinematics of the Tori in Active Galactic Nuclei with the Velocity-resolved Reverberation Mapping of the Narrow Iron K α Line

Energy Technology Data Exchange (ETDEWEB)

Liu Yuan; Li Xiaobo, E-mail: liuyuan@ihep.ac.cn, E-mail: lixb@ihep.ac.cn [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, P.O. Box 918-3, Beijing 100049 (China)

2017-07-20

The properties of the dusty tori in active galactic nuclei (AGNs) have been investigated in detail, mainly focusing on the geometry and components; however, the kinematics of the torus are still not clear. The narrow iron K α line at 6.4 keV is thought to be produced by the X-ray reflection from the torus. Thus, the velocity-resolved reverberation mapping of it is able to constrain the kinematics of the torus. Such effort is limited by the spectral resolution of current charged coupled device (CCD) detectors and should be possible with the microcalorimeter on the next generation X-ray satellite. In this paper, we first construct the response functions of the torus under a uniform inflow, a Keplerian rotation, and a uniform outflow. Then the energy-dependent light curve of the narrow iron K α line is simulated according to the performance of the X-ray Integral Field Unit in Athena. Finally, the energy-dependent cross-correlation function is calculated to reveal the kinematic signal. According to our results, 100 observations with 5 ks exposure of each are sufficient to distinguish the above three velocity fields. Although the real geometry and velocity field of the torus could be more complex than we assumed, the present result proves the feasibility of the velocity-resolved reverberation mapping of the narrow iron K α line. The combination of the dynamics of the torus with those of the broad-line region and the host galaxy is instructive for the understanding of the feeding and feedback process of AGNs.

Uncertainty estimation and multi sensor fusion for kinematic laser tracker measurements

Science.gov (United States)

Ulrich, Thomas

2013-08-01

Laser trackers are widely used to measure kinematic tasks such as tracking robot movements. Common methods to evaluate the uncertainty in the kinematic measurement include approximations specified by the manufacturers, various analytical adjustment methods and the Kalman filter. In this paper a new, real-time technique is proposed, which estimates the 4D-path (3D-position + time) uncertainty of an arbitrary path in space. Here a hybrid system estimator is applied in conjunction with the kinematic measurement model. This method can be applied to processes, which include various types of kinematic behaviour, constant velocity, variable acceleration or variable turn rates. The new approach is compared with the Kalman filter and a manufacturer's approximations. The comparison was made using data obtained by tracking an industrial robot's tool centre point with a Leica laser tracker AT901 and a Leica laser tracker LTD500. It shows that the new approach is more appropriate to analysing kinematic processes than the Kalman filter, as it reduces overshoots and decreases the estimated variance. In comparison with the manufacturer's approximations, the new approach takes account of kinematic behaviour with an improved description of the real measurement process and a reduction in estimated variance. This approach is therefore well suited to the analysis of kinematic processes with unknown changes in kinematic behaviour as well as the fusion among laser trackers.

Analisys and Choice of the Exoskeleton’s Actuator Kinematic Structure

Directory of Open Access Journals (Sweden)

A. A. Vereikin

2014-01-01

Full Text Available The urgency of designing of robotic exoskeletons as one of the most prospective means of modern robotics is proved. A literature review concerning the design issues of anthropomorphic walking robots and exoskeletons is performed. Some problems, accompanying the designing process of exoskeleton actuator, are highlighted. Among them synthesis of its tree-like kinematic structure takes leading place. Its complication is explained by the specific human-machine interaction.The problem of exoskeleton actuator kinematic scheme synthesis is formulated and possible approaches to its solution are shown. The paper presents the synthesis results obtained using the software complex CATIA-based means of ergonomic design. It investigates the degrees of freedom of human-operator’s foot, shin, and thigh. And it identifies a number of shortcomings of this software complex associated with the ambiguity to solve the inverse kinematics problem, leading to a significant complication of kinematics synthesis.A model of human lower limb on which further studies of the exoskeleton actuator kinematic scheme, ensuring fulfillment of the human-operator standard movements (squats, kick their feet, bending body, walking, running stairs, etc., are based, is developed in SolidWorks software complex. The reasonability of the exoskeleton kinematic scheme synthesis in software package SolidWorks using anthropometric data from the software complex CATIA, is justified.The proposed method allows to analyze different kinematic schemes of actuator for the stage of conceptual design and to choose the best of them in accordance with established criterions. Thus, the developer receives the final version of the kinematic scheme before the detailed design of the actuator starts, thus significantly reducing its labor costs.

In vitro quantification of the performance of model-based mono-planar and bi-planar fluoroscopy for 3D joint kinematics estimation.

Science.gov (United States)

Tersi, Luca; Barré, Arnaud; Fantozzi, Silvia; Stagni, Rita

2013-03-01

Model-based mono-planar and bi-planar 3D fluoroscopy methods can quantify intact joints kinematics with performance/cost trade-off. The aim of this study was to compare the performances of mono- and bi-planar setups to a marker-based gold-standard, during dynamic phantom knee acquisitions. Absolute pose errors for in-plane parameters were lower than 0.6 mm or 0.6° for both mono- and bi-planar setups. Mono-planar setups resulted critical in quantifying the out-of-plane translation (error bi-planar in quantifying the rotation along bone longitudinal axis (error bi-planar (error comparable to bi-planar, but with halved computational costs, halved segmentation time and halved ionizing radiation dose. Bi-planar analysis better compensated for the out-of-plane uncertainty that is differently propagated to relative kinematics depending on the setup. To take its full benefits, the motion task to be investigated should be designed to maintain the joint inside the visible volume introducing constraints with respect to mono-planar analysis.

Simultaneous and Continuous Estimation of Shoulder and Elbow Kinematics from Surface EMG Signals

Directory of Open Access Journals (Sweden)

Qin Zhang

2017-05-01

Full Text Available In this paper, we present a simultaneous and continuous kinematics estimation method for multiple DoFs across shoulder and elbow joint. Although simultaneous and continuous kinematics estimation from surface electromyography (EMG is a feasible way to achieve natural and intuitive human-machine interaction, few works investigated multi-DoF estimation across the significant joints of upper limb, shoulder and elbow joints. This paper evaluates the feasibility to estimate 4-DoF kinematics at shoulder and elbow during coordinated arm movements. Considering the potential applications of this method in exoskeleton, prosthetics and other arm rehabilitation techniques, the estimation performance is presented with different muscle activity decomposition and learning strategies. Principle component analysis (PCA and independent component analysis (ICA are respectively employed for EMG mode decomposition with artificial neural network (ANN for learning the electromechanical association. Four joint angles across shoulder and elbow are simultaneously and continuously estimated from EMG in four coordinated arm movements. By using ICA (PCA and single ANN, the average estimation accuracy 91.12% (90.23% is obtained in 70-s intra-cross validation and 87.00% (86.30% is obtained in 2-min inter-cross validation. This result suggests it is feasible and effective to use ICA (PCA with single ANN for multi-joint kinematics estimation in variant application conditions.

Variant and invariant patterns embedded in human locomotion through whole body kinematic coordination.

Science.gov (United States)

Funato, Tetsuro; Aoi, Shinya; Oshima, Hiroko; Tsuchiya, Kazuo

2010-09-01

Step length, cadence and joint flexion all increase in response to increases in gradient and walking speed. However, the tuning strategy leading to these changes has not been elucidated. One characteristic of joint variation that occurs during walking is the close relationship among the joints. This property reduces the number of degrees of freedom and seems to be a key issue in discussing the tuning strategy. This correlation has been analyzed for the lower limbs, but the relation between the trunk and lower body is generally ignored. Two questions about posture during walking are discussed in this paper: (1) whether there is a low-dimensional restriction that determines walking posture, which depends not just on the lower limbs but on the whole body, including the trunk and (2) whether some simple rules appear in different walking conditions. To investigate the correlation, singular value decomposition was applied to a measured walking pattern. This showed that the whole movement can be described by a closed loop on a two-dimensional plane in joint space. Furthermore, by investigating the effect of the walking condition on the decomposed patterns, the position and the tilt of the constraint plane was found to change significantly, while the loop pattern on the constraint plane was shown to be robust. This result indicates that humans select only certain kinematic characteristics for adapting to various walking conditions.

Outflow Kinematics Manifested by the Hα Line: Gas Outflows in Type 2 AGNs. IV

Energy Technology Data Exchange (ETDEWEB)

Kang, Daeun; Woo, Jong-Hak; Bae, Hyun-Jin, E-mail: woo@astro.snu.ac.kr [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of)

2017-08-20

Energetic ionized gas outflows driven by active galactic nuclei (AGNs) have been studied as a key phenomenon related to AGN feedback. To probe the kinematics of the gas in the narrow-line region, [O iii] λ 5007 has been utilized in a number of studies showing nonvirial kinematic properties due to AGN outflows. In this paper, we statistically investigate whether the H α emission line is influenced by AGN-driven outflows by measuring the kinematic properties based on the H α line profile and comparing them with those of [O iii]. Using the spatially integrated spectra of ∼37,000 Type 2 AGNs at z < 0.3 selected from the Sloan Digital Sky Survey DR7, we find a nonlinear correlation between H α velocity dispersion and stellar velocity dispersion that reveals the presence of the nongravitational component, especially for AGNs with a wing component in H α . The large H α velocity dispersion and velocity shift of luminous AGNs are clear evidence of AGN outflow impacts on hydrogen gas, while relatively smaller kinematic properties compared to those of [O iii] imply that the observed outflow effect on the H α line is weaker than the case of [O iii].

Contact kinematics of biomimetic scales

Energy Technology Data Exchange (ETDEWEB)

Ghosh, Ranajay; Ebrahimi, Hamid; Vaziri, Ashkan, E-mail: vaziri@coe.neu.edu [Department of Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts 02115 (United States)

2014-12-08

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

Financial constraint and R&D investment: evidence from CIS

OpenAIRE

Tiwari, A.K.; Mohnen, P.; Palm, F.C.; Schim van der Loeff, S.

2007-01-01

Using direct information on financial constraints from questionnaires, rather than the commonly used balance sheet information, this paper presents evidence that, controlling for traditional factors as size, market share, cooperative arrangement, and expected profitability, financial constraints affect a firm's decision of how much to invest in R&D activities. Apart from these constraints, other hampering factors as market uncertainty and institutional bottlenecks, regulations and organizatio...

The Maiden Voyage of a Kinematics Robot

Science.gov (United States)

Greenwolfe, Matthew L.

2015-04-01

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

Action experience changes attention to kinematic cues

Directory of Open Access Journals (Sweden)

Courtney eFilippi

2016-02-01

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

Effect of suspension kinematic on 14 DOF vehicle model

Science.gov (United States)

Wongpattananukul, T.; Chantharasenawong, C.

2017-12-01

Computer simulations play a major role in shaping modern science and engineering. They reduce time and resource consumption in new studies and designs. Vehicle simulations have been studied extensively to achieve a vehicle model used in minimum lap time solution. Simulation result accuracy depends on the abilities of these models to represent real phenomenon. Vehicles models with 7 degrees of freedom (DOF), 10 DOF and 14 DOF are normally used in optimal control to solve for minimum lap time. However, suspension kinematics are always neglected on these models. Suspension kinematics are defined as wheel movements with respect to the vehicle body. Tire forces are expressed as a function of wheel slip and wheel position. Therefore, the suspension kinematic relation is appended to the 14 DOF vehicle model to investigate its effects on the accuracy of simulate trajectory. Classical 14 DOF vehicle model is chosen as baseline model. Experiment data is collected from formula student style car test runs as baseline data for simulation and comparison between baseline model and model with suspension kinematic. Results show that in a single long turn there is an accumulated trajectory error in baseline model compared to model with suspension kinematic. While in short alternate turns, the trajectory error is much smaller. These results show that suspension kinematic had an effect on the trajectory simulation of vehicle. Which optimal control that use baseline model will result in inaccuracy control scheme.

Nonlinear kinematics for piezoelectricity in ALEGRA-EMMA.

Energy Technology Data Exchange (ETDEWEB)

Mitchell, John Anthony; Fuller, Timothy Jesse

2013-09-01

This report develops and documents nonlinear kinematic relations needed to implement piezoelectric constitutive models in ALEGRA-EMMA [5], where calculations involving large displacements and rotations are routine. Kinematic relationships are established using Gausss law and Faradays law; this presentation on kinematics goes beyond piezoelectric materials and is applicable to all dielectric materials. The report then turns to practical details of implementing piezoelectric models in an application code where material principal axes are rarely aligned with user defined problem coordinate axes. This portion of the report is somewhat pedagogical but is necessary in order to establish documentation for the piezoelectric implementation in ALEGRA-EMMA. This involves transforming elastic, piezoelectric, and permittivity moduli from material principal axes to problem coordinate axes. The report concludes with an overview of the piezoelectric implementation in ALEGRA-EMMA and small verification examples.

Nonlinear kinematic hardening under non-proportional loading

International Nuclear Information System (INIS)

Ottosen, N.S.

1979-07-01

Within the framework of conventional plasticity theory, it is first determined under which conditions Melan-Prager's and Ziegler's kinematic hardening rules result in identical material behaviour. Next, assuming initial isotropy and adopting the von Mises yield criterion, a nonlinear kinematic hardening function is proposed for prediction of metal behaviour. The model assumes that hardening at a specific stress point depends on the direction of the new incremental loading. Hereby a realistic response is obtained for general reversed loading, and a smooth behaviour is assured, even when loading deviates more and more from proportional loading and ultimately results in reversed loading. The predictions of the proposed model for non-proportional loading under plane stress conditions are compared with those of the classical linear kinematic model, the isotropic model and with published experimental data. Finally, the limitations of the proposaed model are discussed. (author)

Oblique transfer of extensional strain between basins of the middle Rio Grande rift, New Mexico: Fault kinematic and paleostress constraints

Science.gov (United States)

Minor, Scott A.; Hudson, Mark R.; Caine, Jonathan S.; Thompson, Ren A.

2013-01-01

The structural geometry of transfer and accommodation zones that relay strain between extensional domains in rifted crust has been addressed in many studies over the past 30 years. However, details of the kinematics of deformation and related stress changes within these zones have received relatively little attention. In this study we conduct the first-ever systematic, multi-basin fault-slip measurement campaign within the late Cenozoic Rio Grande rift of northern New Mexico to address the mechanisms and causes of extensional strain transfer associated with a broad accommodation zone. Numerous (562) kinematic measurements were collected at fault exposures within and adjacent to the NE-trending Santo Domingo Basin accommodation zone, or relay, which structurally links the N-trending, right-stepping en echelon Albuquerque and Española rift basins. The following observations are made based on these fault measurements and paleostresses computed from them. (1) Compared to the typical northerly striking normal to normal-oblique faults in the rift basins to the north and south, normal-oblique faults are broadly distributed within two merging, NE-trending zones on the northwest and southeast sides of the Santo Domingo Basin. (2) Faults in these zones have greater dispersion of rake values and fault strikes, greater dextral strike-slip components over a wide northerly strike range, and small to moderate clockwise deflections of their tips. (3) Relative-age relations among fault surfaces and slickenlines used to compute reduced stress tensors suggest that far-field, ~E-W–trending σ3 stress trajectories were perturbed 45° to 90° clockwise into NW to N trends within the Santo Domingo zones. (4) Fault-stratigraphic age relations constrain the stress perturbations to the later stages of rifting, possibly as late as 2.7–1.1 Ma. Our fault observations and previous paleomagnetic evidence of post–2.7 Ma counterclockwise vertical-axis rotations are consistent with increased

Kinematic models of extensional structures

International Nuclear Information System (INIS)

Groshong, R.H. Jr.

1990-01-01

This paper discusses kinematic models that can relate faults of different types and different positions within a single dynamic system and thereby offer the potential to explain the disparate seismic activity characteristic of extensional terrains. The major styles are full grabens, half grabens, domino blocks, and glide-block systems. Half grabens, the most likely models for Basin and Range structure, are formed above a master fault of decreasing dip with depth and a hangingwall that deforms as it passes over the curved fault. Second-order normal faults, typically domino style, accommodate the required hangingwall deformation. According to the author low-angle detachment faults are consistent with the evidence of seismicity only on high-angle faults if the hangingwall of the detachment is broken by multiple half-graben systems

Of gluons and gravitons. Exploring color-kinematics duality

International Nuclear Information System (INIS)

Isermann, Reinke Sven

2013-06-01

In this thesis color-kinematics duality will be investigated. This duality is a statement about the kinematical dependence of a scattering amplitude in Yang-Mills gauge theories obeying group theoretical relations similar to that of the color gauge group. The major consequence of this duality is that gravity amplitudes can be related to a certain double copy of gauge theory amplitudes. The main focus of this thesis is on exploring the foundations of color-kinematics duality and its consequences. It is shown how color-kinematics duality can be made manifest at the one-loop level for rational amplitudes. A Lagrangian-based argument will be given for the validity of the double copy construction for these amplitudes including explicit examples at four points. Secondly, it is studied how color-kinematics duality can be used to improve powercounting in gravity theories. To this end the duality is reformulated in terms of linear maps. It is shown as an example how this can be used to derive the large BCFW shift behavior of a gravity integrand constructed through the duality to any loop order up to subtleties inherent to the duality that is addressed. As it becomes clear the duality implies massive cancellations with respect to the usual powercounting of Feynman graphs indicating that gravity theories are much better behaved than naively expected. As another example the linear map approach will be used to investigate the question of UV-finiteness of N=8 supergravity, and it is seen that the amount of cancellations depends on the exact implementation of the duality at loop level. Lastly, color-kinematics duality is considered from a Feynman-graph perspective reproducing some of the results of the earlier chapters thus giving non-trivial evidence for the duality at the loop level from a different perspective.

Of gluons and gravitons. Exploring color-kinematics duality

Energy Technology Data Exchange (ETDEWEB)

Isermann, Reinke Sven

2013-06-15

In this thesis color-kinematics duality will be investigated. This duality is a statement about the kinematical dependence of a scattering amplitude in Yang-Mills gauge theories obeying group theoretical relations similar to that of the color gauge group. The major consequence of this duality is that gravity amplitudes can be related to a certain double copy of gauge theory amplitudes. The main focus of this thesis is on exploring the foundations of color-kinematics duality and its consequences. It is shown how color-kinematics duality can be made manifest at the one-loop level for rational amplitudes. A Lagrangian-based argument will be given for the validity of the double copy construction for these amplitudes including explicit examples at four points. Secondly, it is studied how color-kinematics duality can be used to improve powercounting in gravity theories. To this end the duality is reformulated in terms of linear maps. It is shown as an example how this can be used to derive the large BCFW shift behavior of a gravity integrand constructed through the duality to any loop order up to subtleties inherent to the duality that is addressed. As it becomes clear the duality implies massive cancellations with respect to the usual powercounting of Feynman graphs indicating that gravity theories are much better behaved than naively expected. As another example the linear map approach will be used to investigate the question of UV-finiteness of N=8 supergravity, and it is seen that the amount of cancellations depends on the exact implementation of the duality at loop level. Lastly, color-kinematics duality is considered from a Feynman-graph perspective reproducing some of the results of the earlier chapters thus giving non-trivial evidence for the duality at the loop level from a different perspective.

The influence of heel height on sagittal plane knee kinematics during landing tasks in recreationally active and athletic collegiate females.

Science.gov (United States)

Lindenberg, Kelly M; Carcia, Christopher R; Phelps, Amy L; Martin, Robroy L; Burrows, Anne M

2011-09-01

To determine if heel height alters sagittal plane knee kinematics when landing from a forward hop or drop landing. Knee angles close to extension during landing are theorized to increase ACL injury risk in female athletes. Fifty collegiate females performed two single-limb landing tasks while wearing heel lifts of three different sizes (0, 12 & 24 mm) attached to the bottom of a sneaker. Using an electrogoniometer, sagittal plane kinematics (initial contact [KA(IC)], peak flexion [KA(Peak)], and rate of excursion [RE]) were examined. Repeated measures ANOVAs were used to determine the influence of heel height on the dependent measures. Forward hop task- KA(IC) with 0 mm, 12 mm, and 24 mm lifts were 8.88±6.5, 9.38±5.8 and 11.28±7.0, respectively. Significant differences were noted between 0 and 24 mm lift (psneaker significantly alters sagittal plane knee kinematics upon landing from a unilateral forward hop but not from a drop jump.

Forward and inverse kinematics of double universal joint robot wrists

Science.gov (United States)

Williams, Robert L., II

1991-01-01

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

Kinematic analysis of competitive sprinting | Ansari | African Journal ...

African Journals Online (AJOL)

The results of the study showed that the kinematic variables i.e. knee angle, hip angle, ankle angle, shoulder rotation and extension had a significant influence on sprinting style. The results indicated that the kinematic variables of running style, knee angle at landing, hip flexion, ankle angle at landing, ankle angle at take-off, ...

Inverse kinematic control of LDUA and TWRMS

International Nuclear Information System (INIS)

Yih, T.C.; Burks, B.L.; Kwon, Dong-Soo

1995-01-01

A general inverse kinematic analysis is formulated particularly for the redundant Light Duty Utility Arm (LDUA) and Tank Waste Retrieval Manipulator System (TWRMS). The developed approach is applicable to the inverse kinematic simulation and control of LDUA, TWRMS, and other general robot manipulators. The 4 x 4 homogeneous Cylindrical coordinates-Bryant angles (C-B) notation is adopted to model LDUA, TWRMS, and any robot composed of R (revolute), P (prismatic), and/or S (spherical) joints

Dynamic Control of Kinematically Redundant Robotic Manipulators

Directory of Open Access Journals (Sweden)

Erling Lunde

1987-07-01

Full Text Available Several methods for task space control of kinematically redundant manipulators have been proposed in the literature. Most of these methods are based on a kinematic analysis of the manipulator. In this paper we propose a control algorithm in which we are especially concerned with the manipulator dynamics. The algorithm is particularly well suited for the class of redundant manipulators consisting of a relatively small manipulator mounted on a larger positioning part.

Kinematics in special and general relativity

International Nuclear Information System (INIS)

Woodside, R.W.M.

1979-05-01

This thesis investigates the problem of motion for extended bodies from the viewpoint of classical field theory, where the classical field is the body's energy-momentum or matter tensor. In special relativity a symmetric and divergence-free matter tensor combined with inertial frames is used to generate a kinematics for extended bodies. In general relativity the author suggests an analogous kinematics and applies it to the simplest non-trivial example of static, spherical stars, looking for special sets of vector fields whose matter currents are conserved. Such a set of ten vector fields defines a special frame, and integrals of the conserved matter currents define ten momenta whcih give the kinematics. Application of de Rham cohomology theory shows that the conserved matter currents for isolated bodies will have mechanical potentials which enable the momenta to be found from flux integrals evaluated in the vacuum region surrounding the body. These potentials contain the full Riemann curvature, allowing a body's general relativistic momenta to be determined by its vacuum graviational field

Scapula Kinematics of Youth Baseball Players

Directory of Open Access Journals (Sweden)

Oliver Gretchen

2015-12-01

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

Isotropy of an Upper Limb Exoskeleton and the Kinematics and Dynamics of the Human Arm

Directory of Open Access Journals (Sweden)

Joel C. Perry

2009-01-01

Full Text Available The integration of human and robot into a single system offers remarkable opportunities for a new generation of assistive technology. Despite the recent prominence of upper limb exoskeletons in assistive applications, the human arm kinematics and dynamics are usually described in single or multiple arm movements that are not associated with any concrete activity of daily living (ADL. Moreover, the design of an exoskeleton, which is physically linked to the human body, must have a workspace that matches as close as possible with the workspace of the human body, while at the same time avoid singular configurations of the exoskeleton within the human workspace. The aims of the research reported in this manuscript are (1 to study the kinematics and the dynamics of the human arm during daily activities in a free and unconstrained environment, (2 to study the manipulability (isotropy of a 7-degree-of-freedom (DOF-powered exoskeleton arm given the kinematics and the dynamics of the human arm in ADLs. Kinematic data of the upper limb were acquired with a motion capture system while performing 24 daily activities from six subjects. Utilising a 7-DOF model of the human arm, the equations of motion were used to calculate joint torques from measured kinematics. In addition, the exoskeleton isotropy was calculated and mapped with respect to the spacial distribution of the human arm configurations during the 24 daily activities. The results indicate that the kinematic joint distributions representing all 24 actions appear normally distributed except for elbow flexion–extension with the emergence of three modal centres. Velocity and acceleration components of joint torque distributions were normally distributed about 0 Nm, whereas gravitational component distributions varied with joint. Additionally, velocity effects were found to contribute only 1/100th of the total joint torque, whereas acceleration components contribute 1/10th of the total torque at the

Modifier constraint in alkali borophosphate glasses using topological constraint theory

Energy Technology Data Exchange (ETDEWEB)

Li, Xiang [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zeng, Huidan, E-mail: hdzeng@ecust.edu.cn [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Jiang, Qi [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zhao, Donghui [Unifrax Corporation, Niagara Falls, NY 14305 (United States); Chen, Guorong [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Wang, Zhaofeng; Sun, Luyi [Department of Chemical & Biomolecular Engineering and Polymer Program, Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States); Chen, Jianding [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China)

2016-12-01

In recent years, composition-dependent properties of glasses have been successfully predicted using the topological constraint theory. The constraints of the glass network are derived from two main parts: network formers and network modifiers. The constraints of the network formers can be calculated on the basis of the topological structure of the glass. However, the latter cannot be accurately calculated in this way, because of the existing of ionic bonds. In this paper, the constraints of the modifier ions in phosphate glasses were thoroughly investigated using the topological constraint theory. The results show that the constraints of the modifier ions are gradually increased with the addition of alkali oxides. Furthermore, an improved topological constraint theory for borophosphate glasses is proposed by taking the composition-dependent constraints of the network modifiers into consideration. The proposed theory is subsequently evaluated by analyzing the composition dependence of the glass transition temperature in alkali borophosphate glasses. This method is supposed to be extended to other similar glass systems containing alkali ions.

Biological constraints do not entail cognitive closure.

Science.gov (United States)

Vlerick, Michael

2014-12-01

From the premise that our biology imposes cognitive constraints on our epistemic activities, a series of prominent authors--most notably Fodor, Chomsky and McGinn--have argued that we are cognitively closed to certain aspects and properties of the world. Cognitive constraints, they argue, entail cognitive closure. I argue that this is not the case. More precisely, I detect two unwarranted conflations at the core of arguments deriving closure from constraints. The first is a conflation of what I will refer to as 'representation' and 'object of representation'. The second confuses the cognitive scope of the assisted mind for that of the unassisted mind. Cognitive closure, I conclude, cannot be established from pointing out the (uncontroversial) existence of cognitive constraints. Copyright © 2014 Elsevier Ltd. All rights reserved.

Rigid-body kinematics versus flapping kinematics of a flapping wing micro air vehicle

NARCIS (Netherlands)

Caetano, J.V.; Weehuizen, M.B.; De Visser, C.C.; De Croon, G.C.H.E.; Mulder, M.

2015-01-01

Several formulations have been proposed to model the dynamics of ornithopters, with inconclusive results regarding the need for complex kinematic formulations. Furthermore, the impact of assumptions made in the collected results was never assessed by comparing simulations with real flight data. In

Effects of contracture on gait kinematics: A systematic review.

Science.gov (United States)

Attias, Michael; Chevalley, Odile; Bonnefoy-Mazure, Alice; De Coulon, Geraldo; Cheze, Laurence; Armand, Stéphane

2016-03-01

Contractures of a major joint in the lower limbs may impair human walking in addition to other daily living activities. A contracture is defined as the inability of a joint to perform the full range of motion and excessive resistance during passive mobilization of the joint. Few studies have reported methods describing how to evaluate contractures. Understanding the association among all of these studies seems essential to improve patient management. Therefore, we conducted a systematic review on this topic to elucidate the influence of contractures on gait kinematics. An electronic search in the literature will be conducted. Studies were screened by title and abstract and full texts were evaluated secondarily for definitive inclusion. The quality of the included studies was assessed independently by the two review authors with the Modified Quality Assessment Checklist. The included studies were separated into three categories: pathological contracture versus healthy controls (descriptive), simulated contracture versus healthy controls (experimental), and pre- and post-kinematics after surgical muscle lengthening (surgery). From a total of 4402 references, 112 original articles were selected, and 28 studies were identified in this systematic review. No significant difference between raters was observed on the total score of the Modified Quality Assessment Checklist. Contractures influence walking depending on the location (muscle) and the contracture level (muscle-tendon length). After giving a definition of contracture, this review identified some contracture alterations, such as plantarflexion, knee flexion and hip flexion contractures, with a kinematic description and presented possible different compensations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of treadmill inclination on electromyographic activity and hind limb kinematics in healthy hounds at a walk.

Science.gov (United States)

Lauer, Susanne K; Hillman, Robert B; Li, Li; Hosgood, Giselle L

2009-05-01

To evaluate the effect of treadmill incline on muscle activity and joint range of motion (ROM) in hind limbs of dogs. 8 purpose-bred healthy adult hounds. Activities of the hamstring (semimembranosus, semitendinosus, and biceps femoris muscles), gluteal (superficial, middle, and deep gluteal muscles), and quadriceps (femoris, vastus lateralis, vastus intermedius, and vastus medialis muscles) muscle groups and hip and stifle joint ROM were measured with surface electrogoniometric and myographic sensors in hounds walking on a treadmill at 0.54 m/s at inclines of 5%, 0%, and -5% in random order. Mean electromyographic activities and mean ROMs at each inclination were compared for swing and stance phases. Treadmill inclination did not affect duration of the stance and swing phases or the whole stride. When treadmill inclination was increased from -5% to 5%, hip joint ROM increased and the degree of stifle joint extension decreased significantly. In the beginning of the stance phase, activity of the hamstring muscle group was significantly increased when walking at a 5% incline versus a 5% decline. In the end of the stance phase, that activity was significantly increased when walking at a 5% incline versus at a 5% decline or on a flat surface. Activity of the gluteal and quadriceps muscle groups was not affected when treadmill inclination changed. Treadmill inclination affected joint kinematics only slightly. Walking on a treadmill at a 5% incline had more potential to strengthen the hamstring muscle group than walking on a treadmill with a flat or declined surface.

Kinematic gait analyses in healthy Golden Retrievers

OpenAIRE

Silva, Gabriela C.A.; Cardoso, Mariana Trés; Gaiad, Thais P.; Brolio, Marina P.; Oliveira, Vanessa C.; Assis Neto, Antonio; Martins, Daniele S.; Ambrósio, Carlos E.

2014-01-01

Kinematic analysis relates to the relative movement between rigid bodies and finds application in gait analysis and other body movements, interpretation of their data when there is change, determines the choice of treatment to be instituted. The objective of this study was to standardize the march of Dog Golden Retriever Healthy to assist in the diagnosis and treatment of musculoskeletal disorders. We used a kinematic analysis system to analyse the gait of seven dogs Golden Retriever, female,...

Kinematics and Dynamics of Roller Chain Drives

DEFF Research Database (Denmark)

Fuglede, Niels

There are two main subjects of this work: Kinematic and dynamic modeling and analysis of roller chain drives. In the kinematic analysis we contribute first with a complete treatment of the roller chain drive modeled as a four-bar mechanism. This includes a general, exact and approximate analysis...... which is useful for predicting the characteristic loading of the roller chain drive. As a completely novel contribution, a kinematic model and analysis is presented which includes both spans and sprockets in a simple chain drive system. A general procedure for determination of the total wrapping length...... is presented, which also allows for exact sprocket center positions for a chain with a given number of links. Results show that the total chain wrapping length varies periodically with the tooth frequency. These results are of practical importance to both the design, installation and operation of roller chain...

Probabilistic approach to manipulator kinematics and dynamics

International Nuclear Information System (INIS)

Rao, S.S.; Bhatti, P.K.

2001-01-01

A high performance, high speed robotic arm must be able to manipulate objects with a high degree of accuracy and repeatability. As with any other physical system, there are a number of factors causing uncertainties in the behavior of a robotic manipulator. These factors include manufacturing and assembling tolerances, and errors in the joint actuators and controllers. In order to study the effect of these uncertainties on the robotic end-effector and to obtain a better insight into the manipulator behavior, the manipulator kinematics and dynamics are modeled using a probabilistic approach. Based on the probabilistic model, kinematic and dynamic performance criteria are defined to provide measures of the behavior of the robotic end-effector. Techniques are presented to compute the kinematic and dynamic reliabilities of the manipulator. The effects of tolerances associated with the various manipulator parameters on the reliabilities are studied. Numerical examples are presented to illustrate the procedures

Kinematics and design of a class of parallel manipulators

Science.gov (United States)

Hertz, Roger Barry

1998-12-01

This dissertation is concerned with the kinematic analysis and design of a class of three degree-of-freedom, spatial parallel manipulators. The class of manipulators is characterized by two platforms, between which are three legs, each possessing a succession of revolute, spherical, and revolute joints. The class is termed the "revolute-spherical-revolute" class of parallel manipulators. Two members of this class are examined. The first mechanism is a double-octahedral variable-geometry truss, and the second is termed a double tripod. The history the mechanisms is explored---the variable-geometry truss dates back to 1984, while predecessors of the double tripod mechanism date back to 1869. This work centers on the displacement analysis of these three-degree-of-freedom mechanisms. Two types of problem are solved: the forward displacement analysis (forward kinematics) and the inverse displacement analysis (inverse kinematics). The kinematic model of the class of mechanism is general in nature. A classification scheme for the revolute-spherical-revolute class of mechanism is introduced, which uses dominant geometric features to group designs into 8 different sub-classes. The forward kinematics problem is discussed: given a set of independently controllable input variables, solve for the relative position and orientation between the two platforms. For the variable-geometry truss, the controllable input variables are assumed to be the linear (prismatic) joints. For the double tripod, the controllable input variables are the three revolute joints adjacent to the base (proximal) platform. Multiple solutions are presented to the forward kinematics problem, indicating that there are many different positions (assemblies) that the manipulator can assume with equivalent inputs. For the double tripod these solutions can be expressed as a 16th degree polynomial in one unknown, while for the variable-geometry truss there exist two 16th degree polynomials, giving rise to 256

Graphical constraints: a graphical user interface for constraint problems

OpenAIRE

Vieira, Nelson Manuel Marques

2015-01-01

A constraint satisfaction problem is a classical artificial intelligence paradigm characterized by a set of variables (each variable with an associated domain of possible values), and a set of constraints that specify relations among subsets of these variables. Solutions are assignments of values to all variables that satisfy all the constraints. Many real world problems may be modelled by means of constraints. The range of problems that can use this representation is very diverse and embrace...

Comparison of soft tissue artifact and its effects on knee kinematics between non-obese and obese subjects performing a squatting activity recorded using an exoskeleton.

Science.gov (United States)

Clément, Julien; de Guise, Jaques A; Fuentes, Alexandre; Hagemeister, Nicola

2018-03-01

Rigid attachment systems are one of the methods used to compensate for soft tissue artifact (STA) inherent in joint motion analyses. The goal of this study was to quantify STA of an exoskeleton design to reduce STA at the knee, and to assess the accuracy of 3D knee kinematics recorded with the exoskeleton in non-obese and obese subjects during quasi-static weight-bearing squatting activity using biplane radiography. Nine non-obese and eight obese subjects were recruited. The exoskeleton was calibrated on each subject before they performed a quasistatic squatting activity in the EOS ® imaging system. 3D models of exoskeleton markers and knee bones were reconstructed from EOS ® radiographs; they served to quantify STA and to evaluate differences between the markers and bones knee kinematics during the squatting activity. The results showed that STA observed at the femur was larger in non-obese subjects than in obese subjects in frontal rotation (p = 0.004), axial rotation (p = 0.000), medio-lateral displacement (p = 0.000) and antero-posterior displacement (p = 0.019), while STA observed at the tibia was lower in non-obese subjects than in obese subjects for the three rotations (p exoskeleton were greater among non-obese subjects than obese subjects, which is encouraging for future biomechanical studies on pathologies such as osteoarthritis. Copyright © 2018 Elsevier B.V. All rights reserved.

Cluster algebras in scattering amplitudes with special 2D kinematics

Energy Technology Data Exchange (ETDEWEB)

Torres, Marcus A.C. [Institut de Physique Theorique, CEA-Saclay, Gif-sur-Yvette Cedex (France)

2014-02-15

We study the cluster algebra of the kinematic configuration space Conf{sub n}(P{sup 3}P3) of an n-particle scattering amplitude restricted to the special 2D kinematics. We found that the n-point two-loop MHVremainder function in special 2D kinematics depends on a selection of the X-coordinates that are part of a special structure of the cluster algebra related to snake triangulations of polygons. This structure forms a necklace of hypercube beads in the corresponding Stasheff polytope. Furthermore at n = 12, the cluster algebra and the selection of theX-coordinates in special2Dkinematics replicates the cluster algebra and the selection of X-coordinates of the n = 6 two-loop MHV amplitude in 4D kinematics. (orig.)

Kinematics and Workspace of a 4-DOF Hybrid Palletizing Robot

Directory of Open Access Journals (Sweden)

Yong Tao

2014-06-01

Full Text Available We presented the kinematical analysis of a 4-DOF hybrid palletizing robot. The palletizing robot structure was proposed and the arm model of the robot was presented. The kinematical analysis of the end robotic manipulator was given. As a result, the position, velocity, and acceleration curves as well as the maximum workspace were demonstrated by simulation in Matlab. This study would be useful for the kinematical characteristics of the 4-DOF palletizing robot in space.

S-06: Effect of Increased Cadence on Neuromuscular Response and Lower Limb Kinematics in Middle Distance Runners

Directory of Open Access Journals (Sweden)

Amrinder Singh

2017-03-01

Full Text Available AIM: To examine the differences in the neuromuscular and kinematic response in middle distance runners when the step rate was increased to 5% and 10% respectively of the preferred step rate.MATERIALS AND METHODOLOGY: 80 middle distance runners (40 males and 40 females participated in the study. EMG of 8 muscles (rectus femoris, medial and lateral hamstrings, medial gastrocnemius, tibialis anterior, gluteus medius and maximus, kinematic changes at the lower limb joints during stance and swing phase of running, foot pressure readings and spatiotemporal gait pa-rameters were recorded as each participant ran at their preferred speed, 5% increase in preferred speed and 10% increase in their preferred speed while keeping the treadmill speed constant.RESULTS: Kinematic analysis showed an increased knee flexion angle at initial contact (p < 0.001 and decreased knee flexion angle during swing phase (p < 0.001, Ankle showed reduced dorsiflex-ion angle at initial contact (p<0.001 and the hip showed less peak flexion (p < 0.001 across step rate conditions.With an increase in step rate, a fore foot strike running pattern was seen. Muscle activity was signif-icantly increased during the late swing and pre-swing at 10% of the preferred speed (p<0.001, with less significant changes during 5% of the preferred speed. During loading response, significant de-crease in muscle activity (p<0.05 was found between 5% and 10% increase of preferred speed.CONCLUSION: Increased cadence showed increased muscle activation and a forefoot strike run-ning pattern. The kinematic changes documented along with the neuromuscular response across the step rate conditions could be beneficial to runners for rehabilitation and injury prevention.

Structural and kinematic evolution of a Miocene to Recent sinistral restraining bend: the Montejunto massif, Portugal

Science.gov (United States)

Curtis, Michael L.

1999-01-01

The Montejunto massif lies in the apex of a large-scale restraining bend at the southern termination of a sinistral transpressive fault system, in the Lusitanian basin of Portugal. Cenozoic deformation within the Montejunto massif initiated with southerly directed thrusting along the southern boundary of the massif, in association with the development of the E-W oriented Montejunto anticline, probably during the Langhian. Deformation switched to the northern boundary of the massif, in association with a change to NW-directed thrusting and continued development of the Montejunto anticline. The youngest set of structures within the massif is related to the sinistral reactivation of the Arieiro fault system, and steeply inclined bedding. This late phase of deformation represents the accommodation of a component of sinistral displacement across the restraining bend along mechanical anisotropies formed during this progressive Cenozoic deformation event. Variation in the kinematic style of the Main Arieiro fault is related to the angle ( α) between the fault plane and the displacement vector. Where α≈20°, abrupt pene-contemporaneous switches in displacement direction are recorded along the fault, whereas strike-slip kinematics predominate where α<20°. The timing of deformation events in the Montejunto massif is uncertain. However, correlation with the established Cenozoic Africa/Europe plate convergence directions may provide potential temporal constraints.

A Closed Loop Inverse Kinematics Solver Intended for Offline Calculation Optimized with GA

Directory of Open Access Journals (Sweden)

Emil Dale Bjoerlykhaug

2018-01-01

Full Text Available This paper presents a simple approach to building a robotic control system. Instead of a conventional control system which solves the inverse kinematics in real-time as the robot moves, an alternative approach where the inverse kinematics is calculated ahead of time is presented. This approach reduces the complexity and code necessary for the control system. Robot control systems are usually implemented in low level programming language. This new approach enables the use of high level programming for the complex inverse kinematics problem. For our approach, we implement a program to solve the inverse kinematics, called the Inverse Kinematics Solver (IKS, in Java, with a simple graphical user interface (GUI to load a file with desired end effector poses and edit the configuration of the robot using the Denavit-Hartenberg (DH convention. The program uses the closed-loop inverse kinematics (CLIK algorithm to solve the inverse kinematics problem. As an example, the IKS was set up to solve the kinematics for a custom built serial link robot. The kinematics for the custom robot is presented, and an example of input and output files is also presented. Additionally, the gain of the loop in the IKS is optimized using a GA, resulting in almost a 50% decrease in computational time.

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

Energy Technology Data Exchange (ETDEWEB)

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

1997-01-01

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

The kinematics of machinery outlines of a theory of machines

CERN Document Server

Reuleaux, Franz

2012-01-01

A classic on the kinematics of machinery, this volume was written by the Father of Kinematics. Reuleaux writes with authority and precision, developing the subject from its fundamentals. 450 figures. 1876 edition.

Lingual Kinematics during Rapid Syllable Repetition in Parkinson's Disease

Science.gov (United States)

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

2012-01-01

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

Kinematics and resolution at future ep colliders

International Nuclear Information System (INIS)

Bluemlein, J.; Klein, M.

1992-01-01

Limitations due to resolution and kinematics are discussed of the (Q 2 , x) range accessible with electron-proton colliders after HERA. For the time after HERA one may think of two electron-proton colliders: an asymmetric energy machine and a rather symmetric one. Both colliders are compared here in order to study the influence of the different E l /E p ratios on the accessible kinematic range which is restricted due to angular coverage, finite detector resolution and calibration uncertainties

Human Body Parts Tracking and Kinematic Features Assessment Based on RSSI and Inertial Sensor Measurements

Directory of Open Access Journals (Sweden)

Gaddi Blumrosen

2013-08-01

Full Text Available Acquisition of patient kinematics in different environments plays an important role in the detection of risk situations such as fall detection in elderly patients, in rehabilitation of patients with injuries, and in the design of treatment plans for patients with neurological diseases. Received Signal Strength Indicator (RSSI measurements in a Body Area Network (BAN, capture the signal power on a radio link. The main aim of this paper is to demonstrate the potential of utilizing RSSI measurements in assessment of human kinematic features, and to give methods to determine these features. RSSI measurements can be used for tracking different body parts’ displacements on scales of a few centimeters, for classifying motion and gait patterns instead of inertial sensors, and to serve as an additional reference to other sensors, in particular inertial sensors. Criteria and analytical methods for body part tracking, kinematic motion feature extraction, and a Kalman filter model for aggregation of RSSI and inertial sensor were derived. The methods were verified by a set of experiments performed in an indoor environment. In the future, the use of RSSI measurements can help in continuous assessment of various kinematic features of patients during their daily life activities and enhance medical diagnosis accuracy with lower costs.

Kinematics Analysis and Simulation on Transfer Robot with Six Degrees of Freedom

Directory of Open Access Journals (Sweden)

Yi Lu

2014-08-01

Full Text Available Study focuses on transfer robot with Six Degrees of Freedom, establishing kinematic equation by D-H method, analyzing forward kinematics and obtaining inverse kinematics by using method of inverse transform. Based on vector product, it develops velocity Jacobian matrix of robot. The geometric model of robot virtual prototype is established by SolidWorks software and generates parameters such as mass and moment. Kinematic simulation for robot is performed by Mathematica software and develops curve graph of displacement, velocity and accelerated speed in x, y and z direction in end executor center of robot with measurement, analysis and assessment, which provides foundation for further kinematics analysis and structure optimization as well as motion control of robot.

Effects of Novel Guidance Tubing Gait on Electromyographic Neuromuscular Imbalance and Joint Angular Kinematics During Locomotion in Hemiparetic Stroke Patients.

Science.gov (United States)

Lee, Jeong J; You, Joshua Sung H

2017-12-01

To compare the immediate effects of conventional treadmill gait and guidance tubing gait (GTG) on electromyographic neuromuscular imbalance and knee joint kinematics in hemiparetic gait. Case-control study. University medical center. Participants (N=33; 19 men, 14 women) were patients with hemiparetic stroke (n=18 [experimental]; mean age ± SD, 39.2±16.8y) and healthy controls (n=15; mean age ± SD, 26.3±2.6y). The GTG was provided for approximately 30 minutes and involved application of an assistive guidance force using the tubing, specifically to improve knee joint stabilization during midstance and increase knee joint flexion during midswing phase. Clinical tests included the Korean Mini-Mental State Examination, Modified Ashworth Scale, Berg Balance Scale, manual muscle test, and knee joint range of motion and sensory tests. Knee joint muscle electromyographic and kinematic analyses were determined at pretest and posttest. After the intervention, the experimental group showed significantly greater improvements in balanced quadriceps and hamstring electromyographic coactivation and knee joint kinematics relative to the control group (P=.005). The GTG intervention decreased overactive hamstring activity (P=.018) and reciprocally increased quadriceps activity (Pjoint kinematic analysis showed significant changes in the hemiparetic stroke group (P=.004). This study demonstrates the effectiveness of the tubing gait condition to restore knee joint muscle imbalance and kinematics in individuals with hemiparetic stroke who present with an abnormal hyperextension knee gait. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Driver kinematic and muscle responses in braking events with standard and reversible pre-tensioned restraints: validation data for human models.

Science.gov (United States)

Osth, Jonas; Olafsdóttir, Jóna Marín; Davidsson, Johan; Brolin, Karin

2013-11-01

The objectives of this study are to generate validation data for human models intended for simulation of occupant kinematics in a pre-crash phase, and to evaluate the effect of an integrated safety system on driver kinematics and muscle responses. Eleven male and nine female volunteers, driving a passenger car on ordinary roads, performed maximum voluntary braking; they were also subjected to autonomous braking events with both standard and reversible pre-tensioned restraints. Kinematic data was acquired through film analysis, and surface electromyography (EMG) was recorded bilaterally for muscles in the neck, the upper extremities, and lumbar region. Maximum voluntary contractions (MVCs) were carried out in a driving posture for normalization of the EMG. Seat belt positions, interaction forces, and seat indentions were measured. During normal driving, all muscle activity was below 5% of MVC for females and 9% for males. The range of activity during steady state braking for males and females was 13-44% in the cervical and lumbar extensors, while antagonistic muscles showed a co-contraction of 2.3-19%. Seat belt pre-tension affects both the kinematic and muscle responses of drivers. In autonomous braking with standard restraints, muscle activation occurred in response to the inertial load. With pre-tensioned seat belts, EMG onset occurred earlier; between 71 ms and 176 ms after belt pre-tension. The EMG onset times decreased with repeated trials and were shorter for females than for males. With the results from this study, further improvement and validation of human models that incorporate active musculature will be made possible.

Software Development for the Kinematic Analysis of a Lynx 6 Robot Arm

OpenAIRE

Baki Koyuncu; Mehmet Güzel

2007-01-01

The kinematics of manipulators is a central problem in the automatic control of robot manipulators. Theoretical background for the analysis of the 5 Dof Lynx-6 educational Robot Arm kinematics is presented in this paper. The kinematics problem is defined as the transformation from the Cartesian space to the joint space and vice versa. The Denavit-Harbenterg (D-H) model of representation is used to model robot links and joints in this study. Both forward and inverse kinematics solutions for th...

Construction of spaces of kinematic quantum states for field theories via projective techniques

International Nuclear Information System (INIS)

Okołów, Andrzej

2013-01-01

We present a method of constructing a space of quantum states for a field theory: given phase space of a theory, we define a family of physical systems each possessing a finite number of degrees of freedom, next we define a space of quantum states for each finite system, finally using projective techniques we organize all these spaces into a space of quantum states which corresponds to the original phase space. This construction is kinematic in this sense that it bases merely on the structure of the phase space of a theory and does not take into account possible constraints on the space. The construction is a generalization of a construction by Kijowski—the latter one is limited to theories of linear phase spaces, while the former one is free of this limitation. The method presented in this paper enables to construct a space of quantum states for the teleparallel equivalent of general relativity. (paper)

Sex differences in lower extremity kinematics and patellofemoral kinetics during running.

Science.gov (United States)

Almonroeder, Thomas G; Benson, Lauren C

2017-08-01

The incidence of patellofemoral pain (PFP) is 2 times greater in females compared with males of similar activity levels; however, the exact reason for this discrepancy remains unclear. Abnormal mechanics of the hip and knee in the sagittal, frontal, and transverse planes have been associated with an increased risk of PFP. The purpose of this study was to compare the mechanics of the lower extremity in males and females during running in order to better understand the reason(s) behind the sex discrepancy in PFP. Three-dimensional kinematic and kinetic data were collected as male and female participants completed overground running trials at a speed of 4.0 m · s -1 (±5%). Patellofemoral joint stress (PFJS) was estimated using a sagittal plane knee model. The kinematics of the hip and knee in the frontal and transverse planes were also analysed. Male participants demonstrated significantly greater sagittal plane peak PFJS in comparison with the female participants (P < .001, ES = 1.9). However, the female participants demonstrated 3.5° greater peak hip adduction and 3.4° greater peak hip internal rotation (IR). As a result, it appears that the sex discrepancy in PFP is more likely to be related to differences in the kinematics of the hip in the frontal and transverse planes than differences in sagittal plane PFJS.

Augmented kinematic feedback from haptic virtual reality for dental skill acquisition.

Science.gov (United States)

Suebnukarn, Siriwan; Haddawy, Peter; Rhienmora, Phattanapon; Jittimanee, Pannapa; Viratket, Piyanuch

2010-12-01

We have developed a haptic virtual reality system for dental skill training. In this study we examined several kinds of kinematic information about the movement provided by the system supplement knowledge of results (KR) in dental skill acquisition. The kinematic variables examined involved force utilization (F) and mirror view (M). This created three experimental conditions that received augmented kinematic feedback (F, M, FM) and one control condition that did not (KR-only). Thirty-two dental students were randomly assigned to four groups. Their task was to perform access opening on the upper first molar with the haptic virtual reality system. An acquisition session consisted of two days of ten trials of practice in which augmented kinematic feedback was provided for the appropriate experimental conditions after each trial. One week after, a retention test consisting of two trials without augmented feedback was completed. The results showed that the augmented kinematic feedback groups had larger mean performance scores than the KR-only group in Day 1 of the acquisition and retention sessions (ANOVA, p0.05). The trends in acquisition and retention sessions suggest that the augmented kinematic feedback can enhance the performance earlier in the skill acquisition and retention sessions.

Sex Differences in Tibiocalcaneal Kinematics

Directory of Open Access Journals (Sweden)

Sinclair Jonathan

2014-08-01

Full Text Available Purpose. Female runners typically suffer more from chronic running injuries than age-matched males, although the exact biome-chanical mechanisms behind the increased susceptibility of female runners are unknown. This study aimed to compare sex differences in tibiocalcaneal kinematics during the stance phase of running. Methods. Twenty male and twenty female participants ran at 4.0 m · s–1. Tibiocalcaneal kinematics were measured using an eight-camera motion analysis system and compared using independent samples t tests. Results. Peak eversion and tibial internal rotation angles were shown to be significantly greater in female runners. Conclusions. based on these observations, it was determined that female runners may be at increased risk from chronic injury development in relation to excessive tibiocalcaneal motions in the coronal and transverse planes.

Reproducibility of 3D kinematics and surface electromyography measurements of mastication.

Science.gov (United States)

Remijn, Lianne; Groen, Brenda E; Speyer, Renée; van Limbeek, Jacques; Nijhuis-van der Sanden, Maria W G

2016-03-01

The aim of this study was to determine the measurement reproducibility for a procedure evaluating the mastication process and to estimate the smallest detectable differences of 3D kinematic and surface electromyography (sEMG) variables. Kinematics of mandible movements and sEMG activity of the masticatory muscles were obtained over two sessions with four conditions: two food textures (biscuit and bread) of two sizes (small and large). Twelve healthy adults (mean age 29.1 years) completed the study. The second to the fifth chewing cycle of 5 bites were used for analyses. The reproducibility per outcome variable was calculated with an intraclass correlation coefficient (ICC) and a Bland-Altman analysis was applied to determine the standard error of measurement relative error of measurement and smallest detectable differences of all variables. ICCs ranged from 0.71 to 0.98 for all outcome variables. The outcome variables consisted of four bite and fourteen chewing cycle variables. The relative standard error of measurement of the bite variables was up to 17.3% for 'time-to-swallow', 'time-to-transport' and 'number of chewing cycles', but ranged from 31.5% to 57.0% for 'change of chewing side'. The relative standard error of measurement ranged from 4.1% to 24.7% for chewing cycle variables and was smaller for kinematic variables than sEMG variables. In general, measurements obtained with 3D kinematics and sEMG are reproducible techniques to assess the mastication process. The duration of the chewing cycle and frequency of chewing were the best reproducible measurements. Change of chewing side could not be reproduced. The published measurement error and smallest detectable differences will aid the interpretation of the results of future clinical studies using the same study variables. Copyright © 2015 Elsevier Inc. All rights reserved.

Stellar kinematics and structural properties of virgo cluster dwarf early-type galaxies from the SMAKCED project. I. Kinematically decoupled cores and implications for infallen groups in clusters

Energy Technology Data Exchange (ETDEWEB)

Toloba, E.; Guhathakurta, P. [UCO/Lick Observatory, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States); Van de Ven, G. [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Boissier, S.; Boselli, A. [Laboratoire d' Astrophysique de Marseille-LAM, Université d' Aix-Marseille and CNRS, UMR 7326, 38 rue F. Joliot-Curie, F-13388 Marseille Cedex 13 (France); Den Brok, M. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Falcón-Barroso, J.; Ryś, A. [Instituto de Astrofísica de Canarias, Vía Láctea s/n, La Laguna, Tenerife (Spain); Hensler, G. [Department of Astrophysics, University of Vienna, Türkenschanzstraße 17, 1180 Vienna (Austria); Janz, J.; Lisker, T. [Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstraße 12-14, D-69120 Heidelberg (Germany); Laurikainen, E.; Salo, H. [Division of Astronomy, Department of Physics, University of Oulu, P.O. Box 3000, FI-90014 Oulu (Finland); Paudel, S. [Laboratoire AIM Paris-Saclay, CNRS/INSU, Université Paris Diderot, CEA/IRFU/SAp, F-91191 Gif-sur-Yvette Cedex (France); Peletier, R. F., E-mail: toloba@ucolick.org [Kapteyn Astronomical Institute, Postbus 800, 9700 AV Groningen (Netherlands)

2014-03-10

We present evidence for kinematically decoupled cores (KDCs) in two dwarf early-type (dE) galaxies in the Virgo cluster, VCC 1183 and VCC 1453, studied as part of the SMAKCED stellar absorption-line spectroscopy and imaging survey. These KDCs have radii of 1.''8 (0.14 kpc) and 4.''2 (0.33 kpc), respectively. Each of these KDCs is distinct from the main body of its host galaxy in two ways: (1) inverted sense of rotation and (2) younger (and possibly more metal-rich) stellar population. The observed stellar population differences are probably associated with the KDC, although we cannot rule out the possibility of intrinsic radial gradients in the host galaxy. We describe a statistical analysis method to detect, quantify the significance of, and characterize KDCs in long-slit rotation curve data. We apply this method to the two dE galaxies presented in this paper and to five other dEs for which KDCs have been reported in the literature. Among these seven dEs, there are four significant KDC detections, two marginal KDC detections, and one dE with an unusual central kinematic anomaly that may be an asymmetric KDC. The frequency of occurrence of KDCs and their properties provide important constraints on the formation history of their host galaxies. We discuss different formation scenarios for these KDCs in cluster environments and find that dwarf-dwarf wet mergers or gas accretion can explain the properties of these KDCs. Both of these mechanisms require that the progenitor had a close companion with a low relative velocity. This suggests that KDCs were formed in galaxy pairs residing in a poor group environment or in isolation whose subsequent infall into the cluster quenched star formation.

Examining Acoustic and Kinematic Measures of Articulatory Working Space: Effects of Speech Intensity.

Science.gov (United States)

Whitfield, Jason A; Dromey, Christopher; Palmer, Panika

2018-04-18

The purpose of this study was to examine the effect of speech intensity on acoustic and kinematic vowel space measures and conduct a preliminary examination of the relationship between kinematic and acoustic vowel space metrics calculated from continuously sampled lingual marker and formant traces. Young adult speakers produced 3 repetitions of 2 different sentences at 3 different loudness levels. Lingual kinematic and acoustic signals were collected and analyzed. Acoustic and kinematic variants of several vowel space metrics were calculated from the formant frequencies and the position of 2 lingual markers. Traditional metrics included triangular vowel space area and the vowel articulation index. Acoustic and kinematic variants of sentence-level metrics based on the articulatory-acoustic vowel space and the vowel space hull area were also calculated. Both acoustic and kinematic variants of the sentence-level metrics significantly increased with an increase in loudness, whereas no statistically significant differences in traditional vowel-point metrics were observed for either the kinematic or acoustic variants across the 3 loudness conditions. In addition, moderate-to-strong relationships between the acoustic and kinematic variants of the sentence-level vowel space metrics were observed for the majority of participants. These data suggest that both kinematic and acoustic vowel space metrics that reflect the dynamic contributions of both consonant and vowel segments are sensitive to within-speaker changes in articulation associated with manipulations of speech intensity.

Human Gait Feature Extraction Including a Kinematic Analysis toward Robotic Power Assistance

Directory of Open Access Journals (Sweden)

Mario I. Chacon-Murguia

2012-09-01

Full Text Available The present work proposes a method for human gait and kinematic analysis. Gait analysis consists of the determination of hip, knee and ankle positions through video analysis. Gait kinematic for the thigh and knee is then generated from this data. Evaluations of the gait analysis method indicate an acceptable performance of 86.66% for hip and knee position estimation, and comparable findings with other reported works for gait kinematic. A coordinate systems assignment is performed according to the DH algorithm and a direct kinematic model of the legs is obtained. The legs' angles obtained from the video analysis are applied to the kinematic model in order to revise the application of this model to robotic legs in a power assisted system.

Tibiofemoral and patellofemoral joint 3D-kinematics in patients with posterior cruciate ligament deficiency compared to healthy volunteers

Directory of Open Access Journals (Sweden)

von Eisenhart-Rothe Ruediger

2012-11-01

Full Text Available Abstract Background The posterior cruciate ligament (PCL plays an important role in maintaining physiological kinematics and function of the knee joint. To date mainly in-vitro models or combined magnetic resonance and fluoroscopic systems have been used for quantifying the importance of the PCL. We hypothesized, that both tibiofemoral and patellofemoral kinematic patterns are changed in PCL-deficient knees, which is increased by isometric muscle flexion. Therefore the aim of this study was to simultaneously investigate tibiofemoral and patellofemoral 3D kinematics in patients suffering from PCL deficiency during different knee flexion angles and under neuromuscular activation. Methods We enrolled 12 patients with isolated PCL-insufficiency as well as 20 healthy volunteers. Sagittal MR-images of the knee joint were acquired in different positions of the knee joint (0°, 30°, 90° flexion, with and without flexing isometric muscle activity on a 0.2 Tesla open MR-scanner. After segmentation of the patella, femur and tibia local coordinate systems were established to define the spatial position of these structures in relation to each other. Results At full extension and 30° flexion no significant difference was observed in PCL-deficient knee joints neither for tibiofemoral nor for patellofemoral kinematics. At 90° flexion the femur of PCL-deficient patients was positioned significantly more anteriorly in relation to the tibia and both, the patellar tilt and the patellar shift to the lateral side, significantly increased compared to healthy knee joints. While no significant effect of isometric flexing muscle activity was observed in healthy individuals, in PCL-deficient knee joints an increased paradoxical anterior translation of the femur was observed at 90° flexion compared to the status of muscle relaxation. Conclusions Significant changes in tibiofemoral and patellofemoral joint kinematics occur in patients with isolated PCL

Tibiofemoral and patellofemoral joint 3D-kinematics in patients with posterior cruciate ligament deficiency compared to healthy volunteers.

Science.gov (United States)

von Eisenhart-Rothe, Ruediger; Lenze, Ulrich; Hinterwimmer, Stefan; Pohlig, Florian; Graichen, Heiko; Stein, Thomas; Welsch, Frederic; Burgkart, Rainer

2012-11-26

The posterior cruciate ligament (PCL) plays an important role in maintaining physiological kinematics and function of the knee joint. To date mainly in-vitro models or combined magnetic resonance and fluoroscopic systems have been used for quantifying the importance of the PCL. We hypothesized, that both tibiofemoral and patellofemoral kinematic patterns are changed in PCL-deficient knees, which is increased by isometric muscle flexion. Therefore the aim of this study was to simultaneously investigate tibiofemoral and patellofemoral 3D kinematics in patients suffering from PCL deficiency during different knee flexion angles and under neuromuscular activation. We enrolled 12 patients with isolated PCL-insufficiency as well as 20 healthy volunteers. Sagittal MR-images of the knee joint were acquired in different positions of the knee joint (0°, 30°, 90° flexion, with and without flexing isometric muscle activity) on a 0.2 Tesla open MR-scanner. After segmentation of the patella, femur and tibia local coordinate systems were established to define the spatial position of these structures in relation to each other. At full extension and 30° flexion no significant difference was observed in PCL-deficient knee joints neither for tibiofemoral nor for patellofemoral kinematics. At 90° flexion the femur of PCL-deficient patients was positioned significantly more anteriorly in relation to the tibia and both, the patellar tilt and the patellar shift to the lateral side, significantly increased compared to healthy knee joints. While no significant effect of isometric flexing muscle activity was observed in healthy individuals, in PCL-deficient knee joints an increased paradoxical anterior translation of the femur was observed at 90° flexion compared to the status of muscle relaxation. Significant changes in tibiofemoral and patellofemoral joint kinematics occur in patients with isolated PCL-insufficiency above 30 degrees of flexion compared to healthy volunteers. Since

The Effects of Constraint-Induced Movement Therapy on Activities Important to Independent School Participation of Children with Hemiparesis

Science.gov (United States)

Carney, Joan

2012-01-01

This study investigated the efficacy of constraint-induced movement therapy (CI therapy) on activities important to school participation in children with hemiparesis. Four children, ages 4-0 to 7-10 participated in an intensive CI therapy program in a clinical setting. Constraining casts were worn 24 hours daily. Therapy was delivered 6 hours…

THE INFLUENCE OF HIP STRENGTH ON KNEE KINEMATICS DURING A SINGLE-LEGGED MEDIAL DROP LANDING AMONG COMPETITIVE COLLEGIATE BASKETBALL PLAYERS.

Science.gov (United States)

Suzuki, Hidetomo; Omori, Go; Uematsu, Daisuke; Nishino, Katsutoshi; Endo, Naoto

2015-10-01

A smaller knee flexion angle and larger knee valgus angle during weight-bearing activities have been identified as risk factors for non-contact anterior cruciate ligament (ACL) injuries. To prevent such injuries, attention has been focused on the role of hip strength in knee motion control. However, gender differences in the relationship between hip strength and knee kinematics during weight-bearing activities in the frontal plane have not been evaluated. The purpose of this study was to determine the influence of hip strength on knee kinematics in both genders during a single-legged landing task in the frontal plane. The hypotheses were that 1) subjects with a greater hip strength would demonstrate larger knee flexion and smaller knee valgus and internal rotation angles and 2) no gender differences would exist during the single-legged landing task. Forty-three Japanese collegiate basketball players (20 males, 23 females) participated in this study. Three-dimensional motion analysis was used to evaluate knee kinematics during a single-legged medial drop landing (SML). A hand-held dynamometer was used to assess hip extensor (HEXT), abductor (HAB), and external rotator (in two positions: seated position [SHER] and prone [PHER]) isometric strength. Spearman rank correlation coefficients (ρ) were determined for correlations between hip strength and knee kinematics at initial contact (IC) and peak (PK) during SML (p genders. Hip strength may, therefore, play an important role in knee motion control during sports activities, suggesting that increased hip strength may help to prevent non-contact ACL injuries in athletes of both genders. Moreover, gender-specific programs may be needed to control abnormal knee motion, as the influence of hip strength on knee kinematics may differ based on gender. 3.

In vivo kinematics of a robot-assisted uni- and multi-compartmental knee arthroplasty.

Science.gov (United States)

Watanabe, Toshifumi; Abbasi, Ali Z; Conditt, Michael A; Christopher, Jennifer; Kreuzer, Stefan; Otto, Jason K; Banks, Scott A

2014-07-01

There is great interest in providing reliable and durable treatments for one- and two-compartment arthritic degeneration of the cruciate-ligament intact knee. One approach is to resurface only the diseased compartments with discrete unicompartmental components, retaining the undamaged compartment(s). However, placing multiple small implants into the knee presents a greater surgical challenge than total knee arthroplasty, so it is not certain that the natural knee mechanics can be maintained or restored. The goal of this study was to determine whether near-normal knee kinematics can be obtained with a robot-assisted multi-compartmental knee arthroplasty. Thirteen patients with 15 multi-compartmental knee arthroplasties using haptic robotic-assisted bone preparation were involved in this study. Nine subjects received a medial unicompartmental knee arthroplasty (UKA), three subjects received a medial UKA and patellofemoral (PF) arthroplasty, and three subjects received medial and lateral bi-unicondylar arthroplasty. Knee motions were recorded using video-fluoroscopy an average of 13 months (6-29 months) after surgery during stair and kneeling activities. The three-dimensional position and orientation of the implant components were determined using model-image registration techniques. Knee kinematics during maximum flexion kneeling showed femoral external rotation and posterior lateral condylar translation. All knees showed femoral external rotation and posterior condylar translation with flexion during the step activity. Knees with medial UKA and PF arthroplasty showed the most femoral external rotation and posterior translation, and knees with bicondylar UKA showed the least. Knees with accurately placed uni- or bi-compartmental arthroplasty exhibited stable knee kinematics consistent with intact and functioning cruciate ligaments. The patterns of tibiofemoral motion were more similar to natural knees than commonly has been observed in knees with total knee

Scattering forms and the positive geometry of kinematics, color and the worldsheet

Science.gov (United States)

Arkani-Hamed, Nima; Bai, Yuntao; He, Song; Yan, Gongwang

2018-05-01

The search for a theory of the S-Matrix over the past five decades has revealed surprising geometric structures underlying scattering amplitudes ranging from the string worldsheet to the amplituhedron, but these are all geometries in auxiliary spaces as opposed to the kinematical space where amplitudes actually live. Motivated by recent advances providing a reformulation of the amplituhedron and planar N = 4 SYM amplitudes directly in kinematic space, we propose a novel geometric understanding of amplitudes in more general theories. The key idea is to think of amplitudes not as functions, but rather as differential forms on kinematic space. We explore the resulting picture for a wide range of massless theories in general spacetime dimensions. For the bi-adjoint ϕ 3 scalar theory, we establish a direct connection between its "scattering form" and a classic polytope — the associahedron — known to mathematicians since the 1960's. We find an associahedron living naturally in kinematic space, and the tree level amplitude is simply the "canonical form" associated with this "positive geometry". Fundamental physical properties such as locality and unitarity, as well as novel "soft" limits, are fully determined by the combinatorial geometry of this polytope. Furthermore, the moduli space for the open string worldsheet has also long been recognized as an associahedron. We show that the scattering equations act as a diffeomorphism between the interior of this old "worldsheet associahedron" and the new "kinematic associahedron", providing a geometric interpretation and simple conceptual derivation of the bi-adjoint CHY formula. We also find "scattering forms" on kinematic space for Yang-Mills theory and the Non-linear Sigma Model, which are dual to the fully color-dressed amplitudes despite having no explicit color factors. This is possible due to a remarkable fact—"Color is Kinematics"— whereby kinematic wedge products in the scattering forms satisfy the same Jacobi

Kinematic analysis of head, trunk, and pelvis movement when people early after stroke reach sideways.

NARCIS (Netherlands)

Verheyden, G.; Duijnhoven, H.J.R. van; Burnett, M.; Littlewood, J.; Kunkel, D.; Ashburn, A.M.

2011-01-01

BACKGROUND: Sideways reaching with the unaffected arm while seated is a component of everyday activities and can be a challenging task early after stroke. Kinematic analysis of a lateral reach task may provide potential rehabilitation strategies. OBJECTIVE: The authors examined the difference

Jefferson Lab E89-044 experiment: study of the quasi-elastic He3(e,e'p)d reaction in parallel kinematics

International Nuclear Information System (INIS)

Penel-Nottaris, E.

2004-07-01

The Jefferson Lab Hall A E89-044 experiment has measured the He 3 (e,e'p) reaction cross-sections. The extraction of the longitudinal and transverse response functions for the two-body break-up He 3 (e,e'p)d reaction in parallel kinematics allows the study of the bound proton electromagnetic properties inside the He 3 nucleus and the involved nuclear mechanisms beyond plane waves approximations, for missing momenta of 0 and +- 300 MeV/c and transferred momenta from 0.8 to 4.1 GeV 2 . Preliminary cross-sections have been obtained after calibration of the experimental setup by fitting theoretical models averaged over the experimental phase-space using a Monte-Carlo simulation. The 8% systematic error on cross-sections is linked mainly to the absolute normalization of the target density: the elastic scattering data analysis will allow to reduce this error. The preliminary results show some disagreement with theoretical predictions for the forward angles kinematics around 0 MeV/c missing momenta and sensitivity to final state interactions and He 3 waves functions for missing momenta of 300 MeV/c. The longitudinal and transverse separation should constraint theoretical models more strongly. (author)

Kinematic and Dynamic Analysis of a Lower Limb Exoskeleton

OpenAIRE

Tawakal Hasnain Baluch; Adnan Masood; Javaid Iqbal; Umer Izhar; Umar Shahbaz Khan

2012-01-01

This paper will provide the kinematic and dynamic analysis of a lower limb exoskeleton. The forward and inverse kinematics of proposed exoskeleton is performed using Denevit and Hartenberg method. The torques required for the actuators will be calculated using Lagrangian formulation technique. This research can be used to design the control of the proposed exoskeleton.

Scapular kinematics during manual wheelchair propulsion in able-bodied participants

NARCIS (Netherlands)

Bekker, Michel J.; Vegter, Riemer J.K.; van der Scheer, Jan W.; Hartog, Johanneke; de Groot, Sonja; de Vries, Wiebe; Arnet, Ursina; van der Woude, Lucas H.V.; Veeger, Dirkjan (.H.E.J)

Background: Altered scapular kinematics have been associated with shoulder pain and functional limitations. To understand kinematics in persons with spinal cord injury during manual handrim wheelchair propulsion, a description of normal scapular behaviour in able-bodied persons during this specific

Scapular kinematics during manual wheelchair propulsion in able-bodied participants

NARCIS (Netherlands)

Bekker, Michel J; Vegter, Riemer J K; van der Scheer, Jan W; Hartog, Johanneke; de Groot, Sonja; de Vries, Wiebe; Arnet, Ursina; van der Woude, Lucas H V; Veeger, Dirkjan H E J

BACKGROUND: Altered scapular kinematics have been associated with shoulder pain and functional limitations. To understand kinematics in persons with spinal cord injury during manual handrim wheelchair propulsion, a description of normal scapular behaviour in able-bodied persons during this specific

Kinematic Fitting of Detached Vertices

Energy Technology Data Exchange (ETDEWEB)

Mattione, Paul [Rice Univ., Houston, TX (United States)

2007-05-01

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

Sex Differences in Anthropometrics and Heading Kinematics Among Division I Soccer Athletes.

Science.gov (United States)

Bretzin, Abigail C; Mansell, Jamie L; Tierney, Ryan T; McDevitt, Jane K

Soccer players head the ball repetitively throughout their careers; this is also a potential mechanism for a concussion. Although not all soccer headers result in a concussion, these subconcussive impacts may impart acceleration, deceleration, and rotational forces on the brain, leaving structural and functional deficits. Stronger neck musculature may reduce head-neck segment kinematics. The relationship between anthropometrics and soccer heading kinematics will not differ between sexes. The relationship between anthropometrics and soccer heading kinematics will not differ between ball speeds. Pilot, cross-sectional design. Level 3. Division I soccer athletes (5 male, 8 female) were assessed for head-neck anthropometric and neck strength measurements in 6 directions (ie, flexion, extension, right and left lateral flexions and rotations). Participants headed the ball 10 times (25 or 40 mph) while wearing an accelerometer secured to their head. Kinematic measurements (ie, linear acceleration and rotational velocity) were recorded at 2 ball speeds. Sex differences were observed in neck girth ( t = 5.09, P soccer heading kinematics for sex and ball speeds. Neck girth and neck strength are factors that may limit head impact kinematics.

Electrical constraints on electronic components: syntheses of the ETTC'97 and RADECS 97 congress activities

International Nuclear Information System (INIS)

Carel, Ch.

1998-01-01

The electromagnetic compatibility (EMC) of systems and their hardening against electromagnetic (IEMN, lightning, strong radio and radar fields..) and radiative environments impose severe manufacturing constraints in competition with other functional constraints, like thermal constraints and weight, and operational constraints (maintenance, availability). This paper is a summary of the main topics discussed during the ETTC and RADECS 1997 congresses. The outstanding facts concern: the non-disturbance of components (hyper-frequency EMC and high fields), the non-destruction of components (hardening against electromagnetic pulses), the civil domain, the numerical simulations, the integrity of electronic card signals, and the reliability of components. (J.S.)

Kinematics of machinery through hyperworks

CERN Document Server

Rao, J S

2011-01-01

Using animations, this book explains the theory of machines concepts and the evolution of Kinematics. The book adopts HyperWorks MotionSolve to perform the analysis and visualizations, though the book is independent of the requirement of any software.

Kinematic measurements using an infrared sensor

International Nuclear Information System (INIS)

Marinho, F; Paulucci, L

2016-01-01

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

The kinematic advantage of electric cars

Science.gov (United States)

Meyn, Jan-Peter

2015-11-01

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

An introduction to the mathematics of ocular kinematics

Directory of Open Access Journals (Sweden)

Graeme E MacKenzie

2006-12-01

Full Text Available The research surrounding ocular kinematics has widespread applications including the study of binocular vision, virtual reality and the detec-tion of ocular and neurologic pathologies. This field promises to have a significant impact on optometric diagnostic techniques. This paper in-troduces the terminology used in the description of eye rotations and explores a number of the mathematical approaches pertinent to the topic of ocular kinematics.

Effects of social intention on movement kinematics in cooperative actions

Directory of Open Access Journals (Sweden)

Francois eQuesque

2013-10-01

Full Text Available Optimal control models of biological movements are used to account for those internal variables that constrain voluntary goal-directed actions. They however do not take into account external environmental constraints as those associated to social intention. We investigated here the effects of the social context on kinematic characteristics of sequential actions consisting in placing an object on an initial pad (preparatory action before reaching and grasping as fast as possible the object to move it to another location (main action. Reach-to-grasp actions were performed either in an isolated condition or in the presence of a partner (audience effect, located in the near or far space (effect of shared reachable space, and who could intervene on the object in a systematic fashion (effect of social intention effect or not (effect of social uncertainty. Results showed an absence of audience effect but nevertheless an influence of the social context both on the main and the preparatory actions. In particular, a localized effect of shared reachable space was observed on the main action, which was smoother when performed within the reachable space of the partner. Furthermore, a global effect of social uncertainty was observed on both actions with faster and jerkier movements. Finally, social intention affected the preparatory action with higher wrist displacements and slower movements when the object was placed for the partner rather than placed for self-use. Overall, these results demonstrate specific effects of action space, social uncertainty and social intention on the planning of reach-to-grasp actions, in particular on the preparatory action, which was performed with no specific execution constraint. These findings underline the importance of considering the social context in optimal models of action control for human-robot interactions, in particular when focusing on the implementation of motor parameters required to afford intuitive

Joint kinematics estimation using a multi-body kinematics optimisation and an extended Kalman filter, and embedding a soft tissue artefact model.

Science.gov (United States)

Bonnet, Vincent; Richard, Vincent; Camomilla, Valentina; Venture, Gentiane; Cappozzo, Aurelio; Dumas, Raphaël

2017-09-06

To reduce the impact of the soft tissue artefact (STA) on the estimate of skeletal movement using stereophotogrammetric and skin-marker data, multi-body kinematics optimisation (MKO) and extended Kalman filters (EKF) have been proposed. This paper assessed the feasibility and efficiency of these methods when they embed a mathematical model of the STA and simultaneously estimate the ankle, knee and hip joint kinematics and the model parameters. A STA model was used that provides an estimate of the STA affecting the marker-cluster located on a body segment as a function of the kinematics of the adjacent joints. The MKO and the EKF were implemented with and without the STA model. To assess these methods, intra-cortical pin and skin markers located on the thigh, shank, and foot of three subjects and tracked during the stance phase of running were used. Embedding the STA model in MKO and EKF reduced the average RMS of marker tracking from 12.6 to 1.6mm and from 4.3 to 1.9mm, respectively, showing that a STA model trial-specific calibration is feasible. Nevertheless, with the STA model embedded in MKO, the RMS difference between the estimated and the reference joint kinematics determined from the pin markers slightly increased (from 2.0 to 2.1deg) On the contrary, when the STA model was embedded in the EKF, this RMS difference was slightly reduced (from 2.0 to 1.7deg) thus showing a better potentiality of this method to attenuate STA effects and improve the accuracy of joint kinematics estimate. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

Energy Technology Data Exchange (ETDEWEB)

Unseren, M.A.

1993-04-01

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

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

International Nuclear Information System (INIS)

Unseren, M.A.

1993-04-01

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

From physical dose constraints to equivalent uniform dose constraints in inverse radiotherapy planning

International Nuclear Information System (INIS)

Thieke, Christian; Bortfeld, Thomas; Niemierko, Andrzej; Nill, Simeon

2003-01-01

Optimization algorithms in inverse radiotherapy planning need information about the desired dose distribution. Usually the planner defines physical dose constraints for each structure of the treatment plan, either in form of minimum and maximum doses or as dose-volume constraints. The concept of equivalent uniform dose (EUD) was designed to describe dose distributions with a higher clinical relevance. In this paper, we present a method to consider the EUD as an optimization constraint by using the method of projections onto convex sets (POCS). In each iteration of the optimization loop, for the actual dose distribution of an organ that violates an EUD constraint a new dose distribution is calculated that satisfies the EUD constraint, leading to voxel-based physical dose constraints. The new dose distribution is found by projecting the current one onto the convex set of all dose distributions fulfilling the EUD constraint. The algorithm is easy to integrate into existing inverse planning systems, and it allows the planner to choose between physical and EUD constraints separately for each structure. A clinical case of a head and neck tumor is optimized using three different sets of constraints: physical constraints for all structures, physical constraints for the target and EUD constraints for the organs at risk, and EUD constraints for all structures. The results show that the POCS method converges stable and given EUD constraints are reached closely

Elementary introduction to relativistic kinematics

International Nuclear Information System (INIS)

Gerber, H.J.

1979-01-01

This paper includes the most important results and applications of the theory of special relativity to high energy phenomena; it provides an analysis of the kinematics of particle decays and reactions as well as an introduction to the Lorentz group

Multi-Objective Patch Optimization with Integrated Kinematic Draping Simulation for Continuous–Discontinuous Fiber-Reinforced Composite Structures

Directory of Open Access Journals (Sweden)

Benedikt Fengler

2018-03-01

Full Text Available Discontinuous fiber-reinforced polymers (DiCoFRP in combination with local continuous fiber reinforced polymers (CoFRP provide both a high design freedom and high weight-specific mechanical properties. For the optimization of CoFRP patches on complexly shaped DiCoFRP structures, an optimization strategy is needed which considers manufacturing constraints during the optimization procedure. Therefore, a genetic algorithm is combined with a kinematic draping simulation. To determine the optimal patch position with regard to structural performance and overall material consumption, a multi-objective optimization strategy is used. The resulting Pareto front and a corresponding heat-map of the patch position are useful tools for the design engineer to choose the right amount of reinforcement. The proposed patch optimization procedure is applied to two example structures and the effect of different optimization setups is demonstrated.

STRUCTURAL IDENTIFICATION OF DISTINCT INVERSIONS OF PLANAR KINEMATIC CHAINS

Directory of Open Access Journals (Sweden)

Dr. Shubhashis Sanyal

2011-12-01

Full Text Available 0 0 1 171 979 International Islamic University 8 2 1148 14.0 Normal 0 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Times New Roman";} Inversions are various structural possibilities of a kinematic chain. The number of inversions depends on the number of links of a kinematic chain. At the stage of structural synthesis, identification of distinct structural inversions of a particular type of kinematic chain is necessary. Various researchers have proposed methods for identification of distinct inversions. Present method based on Link joint connectivity is proposed to identify the distinct inversions of a planar kinematic chain. Method is tested successfully on single degree and multiple degree of freedom planar kinematic chains. ABSTRAK: Penyonsangan merupakan kebarangkalian pelbagai struktur suatu rangkaian kinematik. Jumlah songsangan bergantung kepada jumlah hubungan suatu rangkaian kinematik. Pada peringkat sintesis struktur, pengenalan songsangan struktur yang berbeza untuk suatu jenis rangkaian kinematik adalah perlu. Ramai penyelidik telah mencadangkan pelbagai kaedah pengenalan songsangan yang berbeza. Kaedah terkini berdasarkan hubungan kesambungan bersama telah dicadangkan untuk mengenalpasti songsangan yang berbeza dalam suatu satah rangkaian kinematik.

Physically coupling two objects in a bimanual task alters kinematics but not end-state comfort.

Science.gov (United States)

Hughes, Charmayne M L; Haddad, Jeffrey M; Franz, Elizabeth A; Zelaznik, Howard N; Ryu, Joong Hyun

2011-06-01

People often grasp objects with an awkward grip to ensure a comfortable hand posture at the end of the movement. This end-state comfort effect is a predominant constraint during unimanual movements. However, during bimanual movements the tendency for both hands to satisfy end-state comfort is affected by factors such as end-orientation congruency and task context. Although bimanual end-state comfort has been examined when the hands manipulate two independent objects, no research has examined end-state comfort when the hands are required to manipulate two physically-coupled objects. In the present experiment, kinematics and grasp behavior during a unimanual and bimanual reaching and placing tasks were examined, when the hands manipulate two physically-connected objects. Forty-five participants were assigned to one of three groups; unimanual, bimanual no-spring (the objects were not physically connected), and bimanual spring (the objects were connected by a spring), and instructed to grasp and place objects in various end-orientations, depending on condition. Physically connecting the objects did not affect end-state comfort prevalence. However, it resulted in decreased interlimb coupling. This finding supports the notion of a flexible constraint hierarchy, in which action goals guide the selection of lower level action features (i.e., hand grip used for grasping), and the particular movements used to accomplish that goal (i.e., interlimb coupling) are controlled throughout the movement.

General analytical shakedown solution for structures with kinematic hardening materials

Science.gov (United States)

Guo, Baofeng; Zou, Zongyuan; Jin, Miao

2016-09-01

The effect of kinematic hardening behavior on the shakedown behaviors of structure has been investigated by performing shakedown analysis for some specific problems. The results obtained only show that the shakedown limit loads of structures with kinematic hardening model are larger than or equal to those with perfectly plastic model of the same initial yield stress. To further investigate the rules governing the different shakedown behaviors of kinematic hardening structures, the extended shakedown theorem for limited kinematic hardening is applied, the shakedown condition is then proposed, and a general analytical solution for the structural shakedown limit load is thus derived. The analytical shakedown limit loads for fully reversed cyclic loading and non-fully reversed cyclic loading are then given based on the general solution. The resulting analytical solution is applied to some specific problems: a hollow specimen subjected to tension and torsion, a flanged pipe subjected to pressure and axial force and a square plate with small central hole subjected to biaxial tension. The results obtained are compared with those in literatures, they are consistent with each other. Based on the resulting general analytical solution, rules governing the general effects of kinematic hardening behavior on the shakedown behavior of structure are clearly.

Comparison of Kinematics and Muscle Activation in Free-Weight Back Squat With and Without Elastic Bands.

Science.gov (United States)

Saeterbakken, Atle H; Andersen, Vidar; van den Tillaar, Roland

2016-04-01

The purpose of the study was to compare kinematic muscle activation when performing 6 repetition maximum (6RM) squats using constant (free weights) or variable resistance (free weights + elastic bands). Twenty recreationally trained women were recruited with 4.6 ± 2.1 years of resistance training experience and a relative strength (6RM/body mass) of 1.1. After a familiarization session identifying the 6RM loads, the participants performed 6RM squats using constant and variable resistance in a randomized order. The total resistance in the variable resistance group was similar to the constant resistance in the presticking region (98%), but greater in the sticking region (105%) and the poststicking region (113%). In addition, the presticking barbell velocity was 21.0% greater using variable than constant resistance, but 22.8% lower in the poststicking region. No significant differences in muscle electromyographic activity, time occurrence, and vertical displacement between the squat modalities were observed, except for higher barbell displacement poststicking using variable resistance. It was concluded that, due to differences in total resistance in the different regions performing variable compared with constant resistance, greater barbell velocity was observed in the presticking region and lower resistance was observed in the poststicking region. However, the extra resistance in the sticking and poststicking regions during the variable resistance modality did not cause increased muscle activity. When performing squats with heavy resistance, the authors recommend using variable resistance, but we suggest increasing the percentage resistance from the elastic bands or using chains.

Kinematic power corrections in off-forward hard reactions.

Science.gov (United States)

Braun, V M; Manashov, A N

2011-11-11

We develop a general approach to the calculation of kinematic corrections ∝t/Q(2), m(2)/Q(2) in hard processes which involve momentum transfer from the initial to the final hadron state. As the principal result, the complete expression is derived for the time-ordered product of two electromagnetic currents that includes all kinematic corrections to twist-four accuracy. The results are immediately applicable, e.g., to the studies of deeply virtual Compton scattering.

Surgical gesture classification from video and kinematic data.

Science.gov (United States)

Zappella, Luca; Béjar, Benjamín; Hager, Gregory; Vidal, René

2013-10-01

Much of the existing work on automatic classification of gestures and skill in robotic surgery is based on dynamic cues (e.g., time to completion, speed, forces, torque) or kinematic data (e.g., robot trajectories and velocities). While videos could be equally or more discriminative (e.g., videos contain semantic information not present in kinematic data), they are typically not used because of the difficulties associated with automatic video interpretation. In this paper, we propose several methods for automatic surgical gesture classification from video data. We assume that the video of a surgical task (e.g., suturing) has been segmented into video clips corresponding to a single gesture (e.g., grabbing the needle, passing the needle) and propose three methods to classify the gesture of each video clip. In the first one, we model each video clip as the output of a linear dynamical system (LDS) and use metrics in the space of LDSs to classify new video clips. In the second one, we use spatio-temporal features extracted from each video clip to learn a dictionary of spatio-temporal words, and use a bag-of-features (BoF) approach to classify new video clips. In the third one, we use multiple kernel learning (MKL) to combine the LDS and BoF approaches. Since the LDS approach is also applicable to kinematic data, we also use MKL to combine both types of data in order to exploit their complementarity. Our experiments on a typical surgical training setup show that methods based on video data perform equally well, if not better, than state-of-the-art approaches based on kinematic data. In turn, the combination of both kinematic and video data outperforms any other algorithm based on one type of data alone. Copyright © 2013 Elsevier B.V. All rights reserved.

Improved Inverse Kinematics Algorithm Using Screw Theory for a Six-DOF Robot Manipulator

OpenAIRE

Chen, Qingcheng; Zhu, Shiqiang; Zhang, Xuequn

2015-01-01

Based on screw theory, a novel improved inverse-kinematics approach for a type of six-DOF serial robot, “Qianjiang I”, is proposed in this paper. The common kinematics model of the robot is based on the Denavit-Hartenberg (D-H) notation method while its inverse kinematics has inefficient calculation and complicated solution, which cannot meet the demands of online real-time application. To solve this problem, this paper presents a new method to improve the efficiency of the inverse kinematics...

Kinematic synthesis of a new 3D printing solution

Directory of Open Access Journals (Sweden)

Giberti Hermes

2016-01-01

The object of this article is the kinematic synthesis of a 5Dofs robot, based on two PKM machines, for additive manufacturing in order to compliant with the requirements of this new technology. Robot kinematics have been optimized by genetic algorithm in order to cover the required workspace and the design of the robot and outline of the control system are also given.

Factors associated with cervical kinematic impairments in patients with neck pain.

Science.gov (United States)

Treleaven, Julia; Chen, Xiaoqi; Sarig Bahat, Hilla

2016-04-01

Cervical kinematics have functional relevance and are important for assessment and management in patients with neck disorders. A better understanding of factors that might influence cervical kinematics is required. The aim of this study was to determine any relationships between altered kinematics to the symptoms and signs of sensorimotor impairments, neck pain and disability and fear of neck motion in people with neck pain. Kinematics were measured in 39 subjects with chronic neck pain using a customized virtual reality system. Range of cervical motion, mean and peak velocity, time to peak velocity percentage, number of velocity peaks and accuracy were derived. Correlations between these measures to self-reported (neck pain intensity, disability, fear of motion, dizziness, visual disturbances) and sensorimotor measures and regression analyses were conducted. Range and velocity of motion of cervical rotation appeared to be most related to visual disturbances and pain or dynamic balance. Nevertheless these relationships only explained about 30% of the variance of each measure. Signs and symptoms of sensorimotor dysfunction should be considered and monitored in the management of altered cervical rotation kinematics in patients with chronic neck disorders. Future research should consider the effects of addressing these factors on neck kinematics and vice versa to aid functional recovery in those with neck pain. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Constraint-based reachability

Directory of Open Access Journals (Sweden)

Arnaud Gotlieb

2013-02-01

Full Text Available Iterative imperative programs can be considered as infinite-state systems computing over possibly unbounded domains. Studying reachability in these systems is challenging as it requires to deal with an infinite number of states with standard backward or forward exploration strategies. An approach that we call Constraint-based reachability, is proposed to address reachability problems by exploring program states using a constraint model of the whole program. The keypoint of the approach is to interpret imperative constructions such as conditionals, loops, array and memory manipulations with the fundamental notion of constraint over a computational domain. By combining constraint filtering and abstraction techniques, Constraint-based reachability is able to solve reachability problems which are usually outside the scope of backward or forward exploration strategies. This paper proposes an interpretation of classical filtering consistencies used in Constraint Programming as abstract domain computations, and shows how this approach can be used to produce a constraint solver that efficiently generates solutions for reachability problems that are unsolvable by other approaches.

Constraint-Muse: A Soft-Constraint Based System for Music Therapy

Science.gov (United States)

Hölzl, Matthias; Denker, Grit; Meier, Max; Wirsing, Martin

Monoidal soft constraints are a versatile formalism for specifying and solving multi-criteria optimization problems with dynamically changing user preferences. We have developed a prototype tool for interactive music creation, called Constraint Muse, that uses monoidal soft constraints to ensure that a dynamically generated melody harmonizes with input from other sources. Constraint Muse provides an easy to use interface based on Nintendo Wii controllers and is intended to be used in music therapy for people with Parkinson’s disease and for children with high-functioning autism or Asperger’s syndrome.

A multi-subject evaluation of uncertainty in anatomical landmark location on shoulder kinematic description.

Science.gov (United States)

Langenderfer, Joseph E; Rullkoetter, Paul J; Mell, Amy G; Laz, Peter J

2009-04-01

An accurate assessment of shoulder kinematics is useful for understanding healthy normal and pathological mechanics. Small variability in identifying and locating anatomical landmarks (ALs) has potential to affect reported shoulder kinematics. The objectives of this study were to quantify the effect of landmark location variability on scapular and humeral kinematic descriptions for multiple subjects using probabilistic analysis methods, and to evaluate the consistency in results across multiple subjects. Data from 11 healthy subjects performing humeral elevation in the scapular plane were used to calculate Euler angles describing humeral and scapular kinematics. Probabilistic analyses were performed for each subject to simulate uncertainty in the locations of 13 upper-extremity ALs. For standard deviations of 4 mm in landmark location, the analysis predicted Euler angle envelopes between the 1 and 99 percentile bounds of up to 16.6 degrees . While absolute kinematics varied with the subject, the average 1-99% kinematic ranges for the motion were consistent across subjects and sensitivity factors showed no statistically significant differences between subjects. The description of humeral kinematics was most sensitive to the location of landmarks on the thorax, while landmarks on the scapula had the greatest effect on the description of scapular elevation. The findings of this study can provide a better understanding of kinematic variability, which can aid in making accurate clinical diagnoses and refining kinematic measurement techniques.

Proposal of Constraints Analysis Method Based on Network Model for Task Planning

Science.gov (United States)

Tomiyama, Tomoe; Sato, Tatsuhiro; Morita, Toyohisa; Sasaki, Toshiro

Deregulation has been accelerating several activities toward reengineering business processes, such as railway through service and modal shift in logistics. Making those activities successful, business entities have to regulate new business rules or know-how (we call them ‘constraints’). According to the new constraints, they need to manage business resources such as instruments, materials, workers and so on. In this paper, we propose a constraint analysis method to define constraints for task planning of the new business processes. To visualize each constraint's influence on planning, we propose a network model which represents allocation relations between tasks and resources. The network can also represent task ordering relations and resource grouping relations. The proposed method formalizes the way of defining constraints manually as repeatedly checking the network structure and finding conflicts between constraints. Being applied to crew scheduling problems shows that the method can adequately represent and define constraints of some task planning problems with the following fundamental features, (1) specifying work pattern to some resources, (2) restricting the number of resources for some works, (3) requiring multiple resources for some works, (4) prior allocation of some resources to some works and (5) considering the workload balance between resources.

Energy constraints and organizational change in US production

Energy Technology Data Exchange (ETDEWEB)

1980-12-01

There is still considerable uncertainty about the way in which energy-supply constraints affect industrial thinking and activity. Yet, this is an important issue in determining the effectiveness of conservation programs and in formulating energy policy. The authors expand on a survey of US business attitudes and responses to energy constraints first published in the September 1979 Energy Policy with the results of further analysis of their survey. In particular, they examine correlations between perceived causes and preferred solutions of energy problems, organizational adjustments to energy constraints in energy-intensive industries, and the ways in which production operations have changed in response to supply problems. 5 references, 5 tables.

Primate Anatomy, Kinematics, and Principles for Humanoid Design

Science.gov (United States)

Ambrose, Robert O.; Ambrose, Catherine G.

2004-01-01

The primate order of animals is investigated for clues in the design of Humanoid Robots. The pursuit is directed with a theory that kinematics, musculature, perception, and cognition can be optimized for specific tasks by varying the proportions of limbs, and in particular, the points of branching in kinematic trees such as the primate skeleton. Called the Bifurcated Chain Hypothesis, the theory is that the branching proportions found in humans may be superior to other animals and primates for the tasks of dexterous manipulation and other human specialties. The primate taxa are defined, contemporary primate evolution hypotheses are critiqued, and variations within the order are noted. The kinematic branching points of the torso, limbs and fingers are studied for differences in proportions across the order, and associated with family and genus capabilities and behaviors. The human configuration of a long waist, long neck, and short arms is graded using a kinematic workspace analysis and a set of design axioms for mobile manipulation robots. It scores well. The re emergence of the human waist, seen in early Prosimians and Monkeys for arboreal balance, but lost in the terrestrial Pongidae, is postulated as benefiting human dexterity. The human combination of an articulated waist and neck will be shown to enable the use of smaller arms, achieving greater regions of workspace dexterity than the larger limbs of Gorillas and other Hominoidea.

Hallux valgus surgery affects kinematic parameters during gait.

Science.gov (United States)

Klugarova, Jitka; Janura, Miroslav; Svoboda, Zdenek; Sos, Zdenek; Stergiou, Nicholas; Klugar, Miloslav

2016-12-01

The aim of our study was to compare spatiotemporal parameters and lower limb and pelvis kinematics during the walking in patients with hallux valgus before and after surgery and in relation to a control group. Seventeen females with hallux valgus, who underwent first metatarsal osteotomy, constituted our experimental group. The control group consisted of thirteen females. Kinematic data during walking were obtained using the Vicon MX system. Our results showed that hallux valgus before surgery affects spatiotemporal parameters and lower limb and pelvis kinematics during walking. Hallux valgus surgery further increased the differences that were present before surgery. Specifically after hallux valgus surgery, the walking speed decreased even more (p=0.09, η 2 =0.19) while step time increased (p=0.002, η 2 =0.44) on both legs. The maximum ankle plantar flexion of the operated leg during toe-off decreased to a greater extend (p=0.03, η 2 =0.26). The asymmetry in the hip and the pelvis movements in the frontal plane (present preoperatively) persisted after surgery. Hallux valgus is not an isolated problem of the first ray, which could be just surgically addressed by correcting the foot's alignment. It is a long-term progressive malfunction of the foot affecting the entire kinematic chain of the lower extremity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Acute toxicity effects of perfluorooctane sulfonate on sperm vitality, kinematics and fertilization success in zebrafish

Science.gov (United States)

Xia, Jigang; Niu, Cuijuan

2017-07-01

Perfluorooctane sulfonate (PFOS) has emerged as one of the most concerning contaminants in recent years. This study aimed to investigate the acute toxicity effect of PFOS on sperm viability, kinematics and fertilization success in zebrafish ( Danio rerio). Sperm were activated in aqueous media containing a range of PFOS concentrations (0, 0.09, 0.9 and 9 mg/L). Viabilities and kinematics of the sperm exposed to different PFOS treatments were assessed via computer-assisted sperm analysis (CASA) at 20, 40, 60, and 80 s after activation. PFOS exposure decreased the percentage of motile sperm, the curvilinear velocity (VCL), and the mean angular displacement (MAD) of spermatozoa, but showed no influence on the straight-line velocity (VSL) or the angular path velocity (VAP). Furthermore, a significant decrease in fertilization success was observed in spermatozoa that were exposed to 0.9 mg/L PFOS or more. These findings indicate that PFOS pollution in natural aquatic environment may be a potential threaten to successful reproduction of fish.

The affect of the use of graphical materials on teaching kinematics

International Nuclear Information System (INIS)

Yener, D.

2005-01-01

In this study, a review of literature about graphical materials and kinematics was done. Preparing traditional questions supported by graphical materials on kinematics that applied to 119 first year students at secondary education mathematics department, and physics, chemistry and biology departments at Selcuk University Educational Faculty. The effect of the usage of graphical materials on teaching kinematics were searched. The data obtained from traditional questions and graphical questions were evaluated by using SPSS (Statistical Social Science for Package Program). At the end of this evaluation, it is obvious that if kinematics are taught with graphical materials, students can learn the subject better, thus, they solve the questions easierly and more rapidly. As a result, the students were more successful to solve the questions with graphical materials than traditional questions

Program realization of mathematical model of kinematic calculation of flat lever mechanisms

Directory of Open Access Journals (Sweden)

M. A. Vasechkin

2016-01-01

Full Text Available Calculation of kinematic mechanisms is very time-consuming work. Due to the content of a large number of similar operations can be automated using computers. Forthis purpose, it is necessary to implement a software implementation ofthe mathematical model of calculation of kinematic mechanisms of the second class. In the article on Turbo Pascal presents the text module to library procedures all kinematic studies of planar lever mechanisms of the second class. The determination of the kinematic characteristics of the mechanism and the construction of its provisions, plans, plans, speeds and accelerations carried out on the example of the six-link mechanism. The beginning of the motionless coordinate system coincides with the axis of rotation of the crank AB. It is assumed that the known length of all links, the positions of all additional points of links and the coordinates of all kinematic pairs rack mechanism, i.e. this stage of work to determine the kinematics of the mechanism must be preceded by a stage of synthesis of mechanism (determining missing dimensions of links. Denote the coordinates of point C and considering that the analogues of velocities and accelerations of this point is 0 (stationary point, appeal to the procedure that computes the kinematics group the Assyrians (GA third. Specify kinematic parameters of point D, taking the beginning of the guide slide E at point C, the angle, the analogue of the angular velocity and the analogue of the angular acceleration of the guide is zero, knowing the length of the connecting rod DE and the length of link 5, refer to the procedure for the GA of the second kind. The use of library routines module of the kinematic calculation, makes it relatively simple to organize a simulation of the mechanism motion, to calculate the projection analogues of velocities and accelerations of all links of the mechanism, to build plans of the velocities and accelerations at each position of the mechanism.

Comparison of quasi-static and dynamic squats: a three-dimensional kinematic, kinetic and electromyographic study of the lower limbs.

Science.gov (United States)

Clément, Julien; Hagemeister, Nicola; Aissaoui, Rachid; de Guise, Jacques A

2014-01-01

Numerous studies have described 3D kinematics, 3D kinetics and electromyography (EMG) of the lower limbs during quasi-static or dynamic squatting activities. One study compared these two squatting conditions but only at low speed on healthy subjects, and provided no information on kinetics and EMG of the lower limbs. The purpose of the present study was to contrast simultaneous recordings of 3D kinematics, 3D kinetics and EMG of the lower limbs during quasi-stat ic and fast-dynamic squats in healthy and pathological subjects. Ten subjects were recruited: five healthy and five osteoarthritis subjects. A motion-capture system, force plate, and surface electrodes respectively recorded 3D kinematics, 3D kinetics and EMG of the lower limbs. Each subject performed a quasi-static squat and several fast-dynamic squats from 0° to 70° of knee flexion. The two squatting conditions were compared for positions where quasi-static and fast-dynamic knee flexion-extension angles were similar. Mean differences between quasi-static and fast-dynamic squats were 1.5° for rotations, 1.9 mm for translations, 2.1% of subjects' body weight for ground reaction forces, 6.6 Nm for torques, 11.2 mm for center of pressure, and 6.3% of maximum fast-dynamic electromyographic activities for EMG. Some significant differences (psquats were small. 69.5% of compared data were equivalent. In conclusion, this study showed that quasi-static and fast-dynamic squatting activities are comparable in terms of 3D kinematics, 3D kinetics and EMG, although some reservations still remain. Copyright © 2014 Elsevier B.V. All rights reserved.

Inverse kinematics problem in robotics using neural networks

Science.gov (United States)

Choi, Benjamin B.; Lawrence, Charles

1992-01-01

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

The kinematics of cytotoxic lymphocytes influence their ability to kill target cells.

Directory of Open Access Journals (Sweden)

Purnima Bhat

Full Text Available Cytotoxic lymphocytes (CTL have been reported to show a range of motility patterns from rapid long-range tracking to complete arrest, but how and whether these kinematics affect their ability to kill target cells is not known. Many in vitro killing assays utilize cell lines and tumour-derived cells as targets, which may be of limited relevance to the kinetics of CTL-mediated killing of somatic cells. Here, live-cell microscopy is used to examine the interactions of CTL and primary murine skin cells presenting antigens. We developed a qualitative and quantitative killing assay using extended-duration fluorescence time-lapse microscopy coupled with large-volume objective software-based data analysis to obtain population data of cell-to-cell interactions, motility and apoptosis. In vivo and ex vivo activated antigen-specific cytotoxic lymphocytes were added to primary keratinocyte targets in culture with fluorometric detection of caspase-3 activation in targets as an objective determinant of apoptosis. We found that activated CTL achieved contact-dependent apoptosis of non-tumour targets after a period of prolonged attachment - on average 21 hours - which was determined by target cell type, amount of antigen, and activation status of CTL. Activation of CTL even without engagement of the T cell receptor was sufficient to mobilise cells significantly above baseline, while the addition of cognate antigen further enhanced their motility. Highly activated CTL showed markedly increased vector displacement, and velocity, and lead to increased antigen-specific target cell death. These data show that the inherent kinematics of CTL correlate directly with their ability to kill non-tumour cells presenting cognate antigen.

Design of a Two-Step Calibration Method of Kinematic Parameters for Serial Robots

Science.gov (United States)

WANG, Wei; WANG, Lei; YUN, Chao

2017-03-01

Serial robots are used to handle workpieces with large dimensions, and calibrating kinematic parameters is one of the most efficient ways to upgrade their accuracy. Many models are set up to investigate how many kinematic parameters can be identified to meet the minimal principle, but the base frame and the kinematic parameter are indistinctly calibrated in a one-step way. A two-step method of calibrating kinematic parameters is proposed to improve the accuracy of the robot's base frame and kinematic parameters. The forward kinematics described with respect to the measuring coordinate frame are established based on the product-of-exponential (POE) formula. In the first step the robot's base coordinate frame is calibrated by the unit quaternion form. The errors of both the robot's reference configuration and the base coordinate frame's pose are equivalently transformed to the zero-position errors of the robot's joints. The simplified model of the robot's positioning error is established in second-power explicit expressions. Then the identification model is finished by the least square method, requiring measuring position coordinates only. The complete subtasks of calibrating the robot's 39 kinematic parameters are finished in the second step. It's proved by a group of calibration experiments that by the proposed two-step calibration method the average absolute accuracy of industrial robots is updated to 0.23 mm. This paper presents that the robot's base frame should be calibrated before its kinematic parameters in order to upgrade its absolute positioning accuracy.

A Projected Non-linear Conjugate Gradient Method for Interactive Inverse Kinematics

DEFF Research Database (Denmark)

Engell-Nørregård, Morten; Erleben, Kenny

2009-01-01

Inverse kinematics is the problem of posing an articulated figure to obtain a wanted goal, without regarding inertia and forces. Joint limits are modeled as bounds on individual degrees of freedom, leading to a box-constrained optimization problem. We present A projected Non-linear Conjugate...... Gradient optimization method suitable for box-constrained optimization problems for inverse kinematics. We show application on inverse kinematics positioning of a human figure. Performance is measured and compared to a traditional Jacobian Transpose method. Visual quality of the developed method...

Estimation of continuous multi-DOF finger joint kinematics from surface EMG using a multi-output Gaussian Process.

Science.gov (United States)

Ngeo, Jimson; Tamei, Tomoya; Shibata, Tomohiro

2014-01-01

Surface electromyographic (EMG) signals have often been used in estimating upper and lower limb dynamics and kinematics for the purpose of controlling robotic devices such as robot prosthesis and finger exoskeletons. However, in estimating multiple and a high number of degrees-of-freedom (DOF) kinematics from EMG, output DOFs are usually estimated independently. In this study, we estimate finger joint kinematics from EMG signals using a multi-output convolved Gaussian Process (Multi-output Full GP) that considers dependencies between outputs. We show that estimation of finger joints from muscle activation inputs can be improved by using a regression model that considers inherent coupling or correlation within the hand and finger joints. We also provide a comparison of estimation performance between different regression methods, such as Artificial Neural Networks (ANN) which is used by many of the related studies. We show that using a multi-output GP gives improved estimation compared to multi-output ANN and even dedicated or independent regression models.

Constraints in distortion-invariant target recognition system simulation

Science.gov (United States)

Iftekharuddin, Khan M.; Razzaque, Md A.

2000-11-01

Automatic target recognition (ATR) is a mature but active research area. In an earlier paper, we proposed a novel ATR approach for recognition of targets varying in fine details, rotation, and translation using a Learning Vector Quantization (LVQ) Neural Network (NN). The proposed approach performed segmentation of multiple objects and the identification of the objects using LVQNN. In this current paper, we extend the previous approach for recognition of targets varying in rotation, translation, scale, and combination of all three distortions. We obtain the analytical results of the system level design to show that the approach performs well with some constraints. The first constraint determines the size of the input images and input filters. The second constraint shows the limits on amount of rotation, translation, and scale of input objects. We present the simulation verification of the constraints using DARPA's Moving and Stationary Target Recognition (MSTAR) images with different depression and pose angles. The simulation results using MSTAR images verify the analytical constraints of the system level design.

Degenerate representations from quantum kinematical constraints

International Nuclear Information System (INIS)

Iosifescu, M.; Scutaru, H.

1987-11-01

We present a systematization of previous results concerning the finite-dimensional irreducible L-modules, for semisimple Lie algebras, on which the second-degree irreducible tensors from the enveloping algebra U(L) vanish.(authors)

Kinematic Tests of Small Arms

Science.gov (United States)

2016-03-15

muzzle devices, such as flash suppressors and muzzle compensators, if the items are designed to be operator removable. Use the ammunition that will...muzzle brake or adding a sound suppressor . A kinematics study is also a diagnostic tool to investigate weapon problems such as poor functioning with

On the kinematics of visual binary and multiple stars of the FK4 cataloque

International Nuclear Information System (INIS)

Starikova, G.A.

1981-01-01

Kinematic features of single, binary and multiple stars are considered. To compare kinematics of such stars with the kinematics of single stars the data on positions and proper motions of those stars which are given in the basic catalogue FK4. Single as well as visual binary and multiple stars united because of their limited content in FK4 have been subdivided by spectra and classes of luminosity into groups with account for known kinematic peculiarities of various spectral groups. Kinematic features for the studied spectral groups are given. By the stars of the FK4 catalogue for various spectral classes the difference of kinematic features of single, visual binary and multiple stars is obtained. However the values of these differences need to be specified due to small number of stars included in five of six groups considered

A real-time computational model for estimating kinematics of ankle ligaments.

Science.gov (United States)

Zhang, Mingming; Davies, T Claire; Zhang, Yanxin; Xie, Sheng Quan

2016-01-01

An accurate assessment of ankle ligament kinematics is crucial in understanding the injury mechanisms and can help to improve the treatment of an injured ankle, especially when used in conjunction with robot-assisted therapy. A number of computational models have been developed and validated for assessing the kinematics of ankle ligaments. However, few of them can do real-time assessment to allow for an input into robotic rehabilitation programs. An ankle computational model was proposed and validated to quantify the kinematics of ankle ligaments as the foot moves in real-time. This model consists of three bone segments with three rotational degrees of freedom (DOFs) and 12 ankle ligaments. This model uses inputs for three position variables that can be measured from sensors in many ankle robotic devices that detect postures within the foot-ankle environment and outputs the kinematics of ankle ligaments. Validation of this model in terms of ligament length and strain was conducted by comparing it with published data on cadaver anatomy and magnetic resonance imaging. The model based on ligament lengths and strains is in concurrence with those from the published studies but is sensitive to ligament attachment positions. This ankle computational model has the potential to be used in robot-assisted therapy for real-time assessment of ligament kinematics. The results provide information regarding the quantification of kinematics associated with ankle ligaments related to the disability level and can be used for optimizing the robotic training trajectory.

Differences in foot kinematics between young and older adults during walking.

Science.gov (United States)

Arnold, John B; Mackintosh, Shylie; Jones, Sara; Thewlis, Dominic

2014-02-01

Our understanding of age-related changes to foot function during walking has mainly been based on plantar pressure measurements, with little information on differences in foot kinematics between young and older adults. The purpose of this study was to investigate the differences in foot kinematics between young and older adults during walking using a multi-segment foot model. Joint kinematics of the foot and ankle for 20 young (mean age 23.2 years, standard deviation (SD) 3.0) and 20 older adults (mean age 73.2 years, SD 5.1) were quantified during walking with a 12 camera Vicon motion analysis system using a five segment kinematic model. Differences in kinematics were compared between older adults and young adults (preferred and slow walking speeds) using Student's t-tests or if indicated, Mann-Whitney U tests. Effect sizes (Cohen's d) for the differences were also computed. The older adults had a less plantarflexed calcaneus at toe-off (-9.6° vs. -16.1°, d = 1.0, p = range of motion (ROM) of the midfoot (11.9° vs. 14.8°, d = 1.3, p = young adults. Walking speed did not influence these differences, as they remained present when groups walked at comparable speeds. The findings of this study indicate that independent of walking speed, older adults exhibit significant differences in foot kinematics compared to younger adults, characterised by less propulsion and reduced mobility of multiple foot segments. Copyright © 2013 Elsevier B.V. All rights reserved.

Kinematic Modeling of Distant Galaxies

Directory of Open Access Journals (Sweden)

Kipper Rain

2012-12-01

Full Text Available Evolution of galaxies is one of the most actual topics in astrophysics. Among the most important factors determining the evolution are two galactic components which are difficult or even impossible to detect optically: the gaseous disks and the dark matter halo. We use deep Hubble Space Telescope images to construct a two-component (bulge + disk model for stellar matter distribution of galaxies. Properties of the galactic components are derived using a three-dimensional galaxy modeling software, which also estimates disk thickness and inclination angle. We add a gas disk and a dark matter halo and use hydrodynamical equations to calculate gas rotation and dispersion profiles in the resultant gravitational potential. We compare the kinematic profiles with the Team Keck Redshift Survey observations. In this pilot study, two galaxies are analyzed deriving parameters for their stellar components; both galaxies are found to be disk-dominated. Using the kinematical model, the gas mass and stellar mass ratio in the disk are estimated.

Goal driven kinematic simulation of flexible arm robot for space station missions

Science.gov (United States)

Janssen, P.; Choudry, A.

1987-01-01

Flexible arms offer a great degree of flexibility in maneuvering in the space environment. The problem of transporting an astronaut for extra-vehicular activity using a space station based flexible arm robot was studied. Inverse kinematic solutions of the multilink structure were developed. The technique is goal driven and can support decision making for configuration selection as required for stability and obstacle avoidance. Details of this technique and results are given.

Adaptive control of an exoskeleton robot with uncertainties on kinematics and dynamics.

Science.gov (United States)

Brahmi, Brahim; Saad, Maarouf; Ochoa-Luna, Cristobal; Rahman, Mohammad H

2017-07-01

In this paper, we propose a new adaptive control technique based on nonlinear sliding mode control (JSTDE) taking into account kinematics and dynamics uncertainties. This approach is applied to an exoskeleton robot with uncertain kinematics and dynamics. The adaptation design is based on Time Delay Estimation (TDE). The proposed strategy does not necessitate the well-defined dynamic and kinematic models of the system robot. The updated laws are designed using Lyapunov-function to solve the adaptation problem systematically, proving the close loop stability and ensuring the convergence asymptotically of the outputs tracking errors. Experiments results show the effectiveness and feasibility of JSTDE technique to deal with the variation of the unknown nonlinear dynamics and kinematics of the exoskeleton model.

Three-Dimensional Scapular Kinematics in Patients with Reverse Total Shoulder Arthroplasty during Arm Motion.

Science.gov (United States)

Lee, Kwang Won; Kim, Yong In; Kim, Ha Yong; Yang, Dae Suk; Lee, Gyu Sang; Choy, Won Sik

2016-09-01

There have been few reports on altered kinematics of the shoulder after reverse total shoulder arthroplasty (RTSA). We investigated differences in 3-dimensional (3D) scapular motions assessed using an optical tracking system between RTSA treated shoulders and asymptomatic contralateral shoulders during arm motion. Thirteen patients who underwent RTSA were assessed for active arm elevation in 2 distinct elevation planes (sagittal plane flexion and scapular plane abduction). Their mean age was 72 years (range, 69 to 79 years) and the mean follow-up was 24.4 months (range, 13 to 48 months). The dominant side was the right side in all the 13 patients, and it was also the side treated with RTSA. Scapular kinematics was recorded with an optical tracking system. The scapular kinematics and the scapulohumeral rhythm (SHR) of the RTSA shoulders and asymptomatic contralateral shoulders were recorded and analyzed during arm elevation. There were no significant differences in internal/external rotation and anterior/posterior tilting of the scapula between shoulders during arm motion (p > 0.05). However, upward rotation of the scapula differed significantly during arm motion (p = 0.035 for sagittal plane flexion; p = 0.046 for scapular plane abduction). There were significant differences in the SHR between the two shoulders (p = 0.016 for sagittal plane flexion; p = 0.021 for scapular plane abduction). The shoulder kinematics after RTSA showed significant differences from the contralateral asymptomatic shoulders. Increased upward rotation and decreased SHR after RTSA indicate that RTSA shoulders use more scapulothoracic motion and less glenohumeral motion to elevate the arm.

A Comparison of Moment Rates for the Eastern Mediterranean Region from Competitive Kinematic Models

Science.gov (United States)

Klein, E. C.; Ozeren, M. S.; Shen-Tu, B.; Galgana, G. A.

2017-12-01

Relatively continuous, complex, and long-lived episodes of tectonic deformation gradually shaped the lithosphere of the eastern Mediterranean region into its present state. This large geodynamically interconnected and seismically active region absorbs, accumulates and transmits strains arising from stresses associated with: (1) steady northward convergence of the Arabian and African plates; (2) differences in lithospheric gravitational potential energy; and (3) basal tractions exerted by subduction along the Hellenic and Cyprus Arcs. Over the last twenty years, numerous kinematic models have been built using a variety of assumptions to take advantage of the extensive and dense GPS observations made across the entire region resulting in a far better characterization of the neotectonic deformation field than ever previously achieved. In this study, three separate horizontal strain rate field solutions obtained from three, region-wide, GPS only based kinematic models (i.e., a regional block model, a regional continuum model, and global continuum model) are utilized to estimate the distribution and uncertainty of geodetic moment rates within the eastern Mediterranean region. The geodetic moment rates from each model are also compared with seismic moment release rates gleaned from historic earthquake data. Moreover, kinematic styles of deformation derived from each of the modeled horizontal strain rate fields are examined for their degree of correlation with earthquake rupture styles defined by proximal centroid moment tensor solutions. This study suggests that significant differences in geodetically obtained moment rates from competitive kinematic models may introduce unforeseen bias into regularly updated, geodetically constrained, regional seismic hazard assessments.

A School Experiment in Kinematics: Shooting from a Ballistic Cart

Science.gov (United States)

Kranjc, T.; Razpet, N.

2011-01-01

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

Right-handed currents at B→ K l+l− kinematic endpoint

Indian Academy of Sciences (India)

2017-10-09

Oct 9, 2017 ... The recent LHCb measured values of these observables are used to conclude an evidence of right-handed currents at the kinematic endpoint of this decay mode. As the conclusion is drawn at the maximum dilepton invariant mass square ( q 2 ) kinematic endpoint, it relies only on heavy quark symmetries ...

Constraint and loneliness in agoraphobia: an empirical investigation.

Science.gov (United States)

Pehlivanidis, A; Koulis, S; Papakostas, Y

2014-01-01

While progress in the aetiopathology and treatment of panic disorder is indisputable, research regarding agoraphobia lacks behind. One significant-yet untested- theory by Guidano and Liotti, suggests the existence of inner representations of fear of "constraint" and fear of "loneliness" as two major schemata, important in the pathogenesis and manifestation of agoraphobia. Activation of these schemata may occur in situations in which the patient: (a) feels as in an inescapable trap (constraint) or (b) alone, unprotected and helpless (loneliness). Upon activation, the "constraint" schema elicits such symptoms as asphyxiation, chest pain, difficult breathing, motor agitation and muscular tension, while the "loneliness" schema elicits such symptoms as sensation of tachycardia, weakness of limbs, trembling or fainting. Activation of these schemata by content-compatible stimuli is expected to trigger various, yet distinct, response patterns, both of which are indiscriminately described within the term "agoraphobia". In order to investigate this hypothesis and its possible clinical applications, several mental and physical probes were applied to 20 patients suffering primarily from agoraphobia, and their responses and performance were recorded. Subjects also completed the "10-item Agoraphobia Questionnaire" prepared by our team aiming at assessing cognitions related to Guidano and Liotti's notion of "loneliness" and "constraint". Breath holding (BH) and Hyperventilation (HV) were selected as physical probes. BH was selected as an easily administered hypercapnea - induced clinical procedure, because of its apparent resemblance to the concept of "constraint". Subjects were instructed to hold their breath for as long as they could and stop at will. Similarly, it was hypothesized that HV might represent a physical "loneliness" probe, since it can elicit such symptoms as dizziness, paraesthesias, stiff muscles, cold hands or feet and trembling, reminiscent of a "collapsing

Multi-temporal mapping of a large, slow-moving earth flow for kinematic interpretation

Science.gov (United States)

Guerriero, Luigi; Coe, Jeffrey A.; Revellino, Paola; Guadagno, Francesco M.

2014-01-01

Periodic movement of large, thick landslides on discrete basal surfaces produces modifications of the topographic surface, creates faults and folds, and influences the locations of springs, ponds, and streams (Baum, et al., 1993; Coe et al., 2009). The geometry of the basal-slip surface, which can be controlled by geological structures (e.g., fold axes, faults, etc.; Revellino et al., 2010; Grelle et al., 2011), and spatial variation in the rate of displacement, are responsible for differential deformation and kinematic segmentation of the landslide body. Thus, large landslides are often composed of several distinct kinematic elements. Each element represents a discrete kinematic domain within the main landslide that is broadly characterized by stretching (extension) of the upper part of the landslide and shortening (compression) near the landslide toe (Baum and Fleming, 1991; Guerriero et al., in review). On the basis of this knowledge, we used photo interpretive and GPS field mapping methods to map structures on the surface of the Montaguto earth flow in the Apennine Mountains of southern Italy at a scale of 1:6,000. (Guerriero et al., 2013a; Fig.1). The earth flow has been periodically active since at least 1954. The most extensive and destructive period of activity began on April 26, 2006, when an estimated 6 million m3 of material mobilized, covering and closing Italian National Road SS90, and damaging residential structures (Guerriero et al., 2013b). Our maps show the distribution and evolution of normal faults, thrust faults, strike-slip faults, flank ridges, and hydrological features at nine different dates (October, 1954; June, 1976; June, 1991; June, 2003; June, 2005; May, 2006; October, 2007; July, 2009; and March , 2010) between 1954 and 2010. Within the earth flow we recognized several kinematic elements and associated structures (Fig.2a). Within each kinematic element (e.g. the earth flow neck; Fig.2b), the flow velocity was highest in the middle, and

Kinematic Analysis of 3-DOF Planer Robot Using Artificial Neural Network

Directory of Open Access Journals (Sweden)

Jolly Atit Shah

2012-07-01

Full Text Available Automatic control of the robotic manipulator involves study of kinematics and dynamics as a major issue. This paper involves the forward and inverse kinematics of 3-DOF robotic manipulator with revolute joints. In this study the Denavit- Hartenberg (D-H model is used to model robot links and joints. Also forward and inverse kinematics solution has been achieved using Artificial Neural Networks for 3-DOF robotic manipulator. It shows that by using artificial neural network the solution we get is faster, acceptable and has zero error.

Kinematic Analysis of Speech Sound Sequencing Errors Induced by Delayed Auditory Feedback.

Science.gov (United States)

Cler, Gabriel J; Lee, Jackson C; Mittelman, Talia; Stepp, Cara E; Bohland, Jason W

2017-06-22

Delayed auditory feedback (DAF) causes speakers to become disfluent and make phonological errors. Methods for assessing the kinematics of speech errors are lacking, with most DAF studies relying on auditory perceptual analyses, which may be problematic, as errors judged to be categorical may actually represent blends of sounds or articulatory errors. Eight typical speakers produced nonsense syllable sequences under normal and DAF (200 ms). Lip and tongue kinematics were captured with electromagnetic articulography. Time-locked acoustic recordings were transcribed, and the kinematics of utterances with and without perceived errors were analyzed with existing and novel quantitative methods. New multivariate measures showed that for 5 participants, kinematic variability for productions perceived to be error free was significantly increased under delay; these results were validated by using the spatiotemporal index measure. Analysis of error trials revealed both typical productions of a nontarget syllable and productions with articulatory kinematics that incorporated aspects of both the target and the perceived utterance. This study is among the first to characterize articulatory changes under DAF and provides evidence for different classes of speech errors, which may not be perceptually salient. New methods were developed that may aid visualization and analysis of large kinematic data sets. https://doi.org/10.23641/asha.5103067.

Reduction of Constraints: Applicability of the Homogeneity Constraint for Macrobatch 3

International Nuclear Information System (INIS)

Peeler, D.K.

2001-01-01

The Product Composition Control System (PCCS) is used to determine the acceptability of each batch of Defense Waste Processing Facility (DWPF) melter feed in the Slurry Mix Evaporator (SME). This control system imposes several constraints on the composition of the contents of the SME to define acceptability. These constraints relate process or product properties to composition via prediction models. A SME batch is deemed acceptable if its sample composition measurements lead to acceptable property predictions after accounting for modeling, measurement and analytic uncertainties. The baseline document guiding the use of these data and models is ''SME Acceptability Determination for DWPF Process Control (U)'' by Brown and Postles [1996]. A minimum of three PCCS constraints support the prediction of the glass durability from a given SME batch. The Savannah River Technology Center (SRTC) is reviewing all of the PCCS constraints associated with durability. The purpose of this review is to revisit these constraints in light of the additional knowledge gained since the beginning of radioactive operations at DWPF and to identify any supplemental studies needed to amplify this knowledge so that redundant or overly conservative constraints can be eliminated or replaced by more appropriate constraints

Cluster mislocation in kinematic Sunyaev-Zel'dovich effect extraction

Science.gov (United States)

Calafut, Victoria; Bean, Rachel; Yu, Byeonghee

2017-12-01

We investigate the impact of a variety of analysis assumptions that influence cluster identification and location on the kinematic Sunyaev-Zel'dovich (kSZ) pairwise momentum signal and covariance estimation. Photometric and spectroscopic galaxy tracers from SDSS, WISE, and DECaLs, spanning redshifts 0.05 surveys the statistical and photometric errors will shrink markedly. Our results demonstrate that uncertainties introduced through using galaxy proxies for cluster locations will need to be fully incorporated, and actively mitigated, for the kSZ to reach its full potential as a cosmological constraining tool for dark energy and neutrino physics.

Numerical kinematic transformation calculations for a parallel link manipulator

International Nuclear Information System (INIS)

Killough, S.M.

1993-01-01

Parallel link manipulators are often considered for particular robotic applications because of the unique advantages they provide. Unfortunately, they have significant disadvantages with respect to calculating the kinematic transformations because of the high-order equations that must be solved. Presented is a manipulator design that exploits the mechanical advantages of parallel links yet also has a corresponding numerical kinematic solution that can be solved in real time on common microcomputers

A non-linear kinematic hardening function

International Nuclear Information System (INIS)

Ottosen, N.S.

1977-05-01

Based on the classical theory of plasticity, and accepting the von Mises criterion as the initial yield criterion, a non-linear kinematic hardening function applicable both to Melan-Prager's and to Ziegler's hardening rule is proposed. This non-linear hardening function is determined by means of the uniaxial stress-strain curve, and any such curve is applicable. The proposed hardening function considers the problem of general reversed loading, and a smooth change in the behaviour from one plastic state to another nearlying plastic state is obtained. A review of both the kinematic hardening theory and the corresponding non-linear hardening assumptions is given, and it is shown that material behaviour is identical whether Melan-Prager's or Ziegler's hardening rule is applied, provided that the von Mises yield criterion is adopted. (author)

Altered spinal kinematics and muscle recruitment pattern of the cervical and thoracic spine in people with chronic neck pain during functional task.

Science.gov (United States)

Tsang, Sharon M H; Szeto, Grace P Y; Lee, Raymond Y W

2014-02-01

Knowledge on the spinal kinematics and muscle activation of the cervical and thoracic spine during functional task would add to our understanding of the performance and interplay of these spinal regions during dynamic condition. The purpose of this study was to examine the influence of chronic neck pain on the three-dimensional kinematics and muscle recruitment pattern of the cervical and thoracic spine during an overhead reaching task involving a light weight transfer by the upper limb. Synchronized measurements of the three-dimensional spinal kinematics and electromyographic activities of cervical and thoracic spine were acquired in thirty individuals with chronic neck pain and thirty age- and gender-matched asymptomatic controls. Neck pain group showed a significantly decreased cervical velocity and acceleration while performing the task. They also displayed with a predominantly prolonged coactivation of cervical and thoracic muscles throughout the task cycle. The current findings highlighted the importance to examine differential kinematic variables of the spine which are associated with changes in the muscle recruitment in people with chronic neck pain. The results also provide an insight to the appropriate clinical intervention to promote the recovery of the functional disability commonly reported in patients with neck pain disorders. Copyright © 2013 Elsevier Ltd. All rights reserved.

Fatigue effects on bar kinematics during the bench press.

Science.gov (United States)

Duffey, Michael J; Challis, John H

2007-05-01

The bench press is one of the most popular weight training exercises. Although most training regimens incorporate multiple repetition sets, there are few data describing how the kinematics of a lift change during a set to failure. To examine these changes, recreational lifters (10 men and 8 women) were recruited. The maximum weight each subject could bench press (1RM) was determined. Subjects then performed as many repetitions as possible at 75% of the 1RM load. Three-dimensional kinematic data were recorded and analyzed for all lifts. Statistical analysis revealed that differences between maximal and submaximal lifts and the kinematics of a submaximal lift change as a subject approaches failure in a set. The time to lift the bar more than doubled from the first to the last repetition, causing a decrease in both mean and peak upward velocity. Furthermore, the peak upward velocity occurred much earlier in the lift phase in these later repetitions. The path the bar followed also changed, with subjects keeping the bar more directly over the shoulder during the lift. In general, most of the kinematic variables analyzed became more similar to those of the maximal lift as the subjects progressed through the set, but there was considerable variation between subjects as to which repetition was most like the maximal lift. This study shows that there are definite changes in the lifting kinematics in recreational lifters during a set to failure and suggests it may be particularly important for coaches and less-skilled lifters to focus on developing the proper bar path, rather than reaching momentary muscular failure, in the early part of a training program.

KINEMATICS AND DYNAMICS MODELS OF CYLINDRICAL ROLLER BEARING OF RAILWAY TRANSPORT

Directory of Open Access Journals (Sweden)

A. V. Gaydamaka

2014-05-01

Full Text Available Purpose. Lack of kinematics models and imperfection of the known dynamics models of the roller bearings of railway rolling stock axle-boxes do not allow designing the optimal structure of bearing cages, providing the required service life and reliability of bearing units of wheel sets for cars and locomotives. The studies of kinematics and dynamics of roller bearings of axle boxes for cars and locomotives and modeling of their parts interaction to create the analytical method of bearing cages calculation are necessary. Methodology. This purpose has been achieved due to the modeling of kinematics of the ideal (without gaps and real (taking account the gaps, manufacturing and installation errors bearings, substantiation of the transfer mechanism of motion from the rollers to bearing cage, modeling the dynamics of rolling, research of interaction forces of the rollers with bearing cage. Findings. It is established that the kinematics of ideal bearing is determined by the contact deformations of the rollers and rings, when the kinematics of real bearing depends mainly on the side gaps in the windows of the bearing cage. On the basis of studies of the real bearing kinematics the dynamics models of the rollers and bearing cage interaction were constructed. The conducted studies of kinematics and dynamics of rolling bearings have changed our view of them as of the planetary mechanism, explained the reason of bearing cage loading, and confirmed the possibility of destruction during operation. Originality. It was first proposed a mechanism for motion transfer from the rollers to the bearing cage of roller bearings, consisting in that the side gap in the bearing cage window is reduced gradually multiple of the number of rollers of radial loading area according to the bearing cage motion. The models of roller bearing dynamics, which allow calculating the interaction forces of parts for all modes of operation, were improved. Practical value. Use of the

A quantum kinematics for asymptotically flat gravity

Science.gov (United States)

Campiglia, Miguel; Varadarajan, Madhavan

2015-07-01

We construct a quantum kinematics for asymptotically flat gravity based on the Koslowski-Sahlmann (KS) representation. The KS representation is a generalization of the representation underlying loop quantum gravity (LQG) which supports, in addition to the usual LQG operators, the action of ‘background exponential operators’, which are connection dependent operators labelled by ‘background’ su(2) electric fields. KS states have, in addition to the LQG state label corresponding to one dimensional excitations of the triad, a label corresponding to a ‘background’ electric field that describes three dimensional excitations of the triad. Asymptotic behaviour in quantum theory is controlled through asymptotic conditions on the background electric fields that label the states and the background electric fields that label the operators. Asymptotic conditions on the triad are imposed as conditions on the background electric field state label while confining the LQG spin net graph labels to compact sets. We show that KS states can be realised as wave functions on a quantum configuration space of generalized connections and that the asymptotic behaviour of each such generalized connection is determined by that of the background electric fields which label the background exponential operators. Similar to the spatially compact case, the Gauss law and diffeomorphism constraints are then imposed through group averaging techniques to obtain a large sector of gauge invariant states. It is shown that this sector supports a unitary action of the group of asymptotic rotations and translations and that, as anticipated by Friedman and Sorkin, for appropriate spatial topology, this sector contains states that display fermionic behaviour under 2π rotations.

Landslide Kinematical Analysis through Inverse Numerical Modelling and Differential SAR Interferometry

Science.gov (United States)

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

2015-11-01

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

Analytical Kinematics and Coupled Vibrations Analysis of Mechanical System Operated by Solar Array Drive Assembly

Science.gov (United States)

Sattar, M.; Wei, C.; Jalali, A.; Sattar, R.

2017-07-01

To address the impact of solar array (SA) anomalies and vibrations on performance of precision space-based operations, it is important to complete its accurate jitter analysis. This work provides mathematical modelling scheme to approximate kinematics and coupled micro disturbance dynamics of rigid load supported and operated by solar array drive assembly (SADA). SADA employed in analysis provides a step wave excitation torque to activate the system. Analytical investigations into kinematics is accomplished by using generalized linear and Euler angle coordinates, applying multi-body dynamics concepts and transformations principles. Theoretical model is extended, to develop equations of motion (EoM), through energy method (Lagrange equation). The main emphasis is to research coupled frequency response by determining energies dissipated and observing dynamic behaviour of internal vibratory systems of SADA. The disturbance model captures discrete active harmonics of SADA, natural modes and vibration amplifications caused by interactions between active harmonics and structural modes of mechanical assembly. The proposed methodology can help to predict true micro disturbance nature of SADA operating rigid load. Moreover, performance outputs may be compared against actual mission requirements to assess precise spacecraft controller design to meet next space generation stringent accuracy goals.

Momentum constraint relaxation

International Nuclear Information System (INIS)

Marronetti, Pedro

2006-01-01

Full relativistic simulations in three dimensions invariably develop runaway modes that grow exponentially and are accompanied by violations of the Hamiltonian and momentum constraints. Recently, we introduced a numerical method (Hamiltonian relaxation) that greatly reduces the Hamiltonian constraint violation and helps improve the quality of the numerical model. We present here a method that controls the violation of the momentum constraint. The method is based on the addition of a longitudinal component to the traceless extrinsic curvature A ij -tilde, generated by a vector potential w i , as outlined by York. The components of w i are relaxed to solve approximately the momentum constraint equations, slowly pushing the evolution towards the space of solutions of the constraint equations. We test this method with simulations of binary neutron stars in circular orbits and show that it effectively controls the growth of the aforementioned violations. We also show that a full numerical enforcement of the constraints, as opposed to the gentle correction of the momentum relaxation scheme, results in the development of instabilities that stop the runs shortly

Isolated patellofemoral arthroplasty reproduces natural patellofemoral joint kinematics when the patella is resurfaced.

Science.gov (United States)

Vandenneucker, Hilde; Labey, Luc; Vander Sloten, Jos; Desloovere, Kaat; Bellemans, Johan

2016-11-01

The objectives of this in vitro project were to compare the dynamic three-dimensional patellofemoral kinematics, contact forces, contact areas and contact pressures of a contemporary patellofemoral prosthetic implant with those of the native knee and to measure the influence of patellar resurfacing and patellar thickness. The hypothesis was that these designs are capable to reproduce the natural kinematics but result in higher contact pressures. Six fresh-frozen specimens were tested on a custom-made mechanical knee rig before and after prosthetic trochlear resurfacing, without and with patellar resurfacing in three different patellar thicknesses. Full three-dimensional kinematics were analysed during three different motor tasks, using infrared motion capture cameras and retroflective markers. Patellar contact characteristics were registered using a pressure measuring device. The patellofemoral kinematic behaviour of the patellofemoral arthroplasty was similar to that of the normal knee when the patella was resurfaced, showing only significant (p patellofemoral kinematics acceptable well when the patella was resurfaced. From a kinematic point of view, patellar resurfacing may be advisable. However, the substantially elevated patellar contact pressures remain a point of concern in the decision whether or not to resurface the patella. This study therefore not only adds a new point in the discussion whether or not to resurface the patella, but also supports the claimed advantage that a patellofemoral arthroplasty is capable to reproduce the natural knee kinematics.

Deformation in the hanging wall of Cretaceous HP rocks (Austroalpine Ötztal-Stubai Complex, European Eastern Alps): constraints on timing, conditions and kinematics

Science.gov (United States)

Habler, Gerlinde; Thöni, Martin; Grasemann, Bernhard; Sölva, Helmuth; Cotza, Gianluca

2010-05-01

The position and nature of the tectonic boundary between the Cretaceous eclogite facies metamorphic Texel Complex (Sölva et al. 2005, TC) and the Ötztal-Stubai Complex sensu stricto (OSC) with predominantly pre-Cretaceous tectonometamorphic imprint remained a matter of discussion (Fügenschuh et al. 2009). Sölva et al (2005) described the Cretaceous Schneeberg Normal Fault Zone (SNFZ) as the major tectonic boundary between the exhuming TC and the OSC, where the major portion of ductile deformation was partitioned into the rheologically weak Schneeberg/Monteneve Unit (SMU). In contrast, other authors proposed a model of a coherent vertical crustal section in the southern OSC (Schmid and Haas 1989), which was rotated and exhumed by erosion due to Oligocene large scale refolding (Fügenschuh et al. 2009). Here, new Rb-Sr data of muscovite and biotite from para- and orthogneisses from the Ferwalltal and Timmelsjoch areas (Austria/Italy) were correlated with mineral chemical and structural data in order to constrain the age and kinematics of the predominant deformational imprint in the OSC representing the hanging wall of the SNFZ. In the Ferwalltal the undisturbed OSC/SMU boundary is exposed. Above that boundary an amphibolite facies mylonitic foliation (Sc1) represented by the compositional layering of coarse grained Qtz, Bt and dynamically recrystallized Pl interferes with an overprinting mylonitic foliation (Sc2) with spatially heterogeneous intensity. Sc1-planes were syn-tectonically overgrown by euhedral Grt with single phase continuous prograde chemical zoning and Bt-porphyroblasts. Dc2 postdated garnet growth and caused the formation of SCC' fabrics in Bt-Pl gneisses. Still Qtz recrystallized dynamically, whereas Ms and Bt newly crystallized during Dc2. In the study area, the lithological boundaries in the OSC mainly are subparallel to the predominant foliation Sc1. These planes dip with 45-50° to the NW-NNW and show a WNW-plunging stretching lineation (LSc1

Kinematics and Kinetics of Squat and Deadlift Exercises with Varying Stance Widths

Science.gov (United States)

DeWitt, John K.; Fincke, Renita S.; Logan, Rachel L.

2011-01-01

. However, hip adduction ROM was greater during the NS and SD than during the ND. Hip rotation ROM was greater during the WS than during the NS and SD, and was greater during the SD than during the ND. For knee and ankle flexion ROM, the ND, WS, and SD were not different, but ROM was greater during the NS than the ND and greater during the WS than the SD. Total eccentric work was greater during the WS than the SD. Otherwise, there were no differences in eccentric or concentric work between conditions. CONCLUSIONS: Although squat and deadlift exercises consist of similar motions, there are kinematic differences between them that depend on stance width. Total eccentric and concentric work are similar for different lifts, but differing kinematics may require activation of different musculature for each variation. With respect to each condition, in the ND the ROM of each joint tended to be less, and the WS tended to trade knee motion for hip motion. PRACTICAL APPLICATIONS: Knowledge of differences in kinematics and kinetics between different squat and deadlift variations is important for coaches and rehabilitation personnel to understand when prescribing exercise. Our results suggest that each variation of the squat and deadlift should be considered a separate exercise that may induce different long-term training effects.

Kinematics of roller chain drives - Exact and approximate analysis

DEFF Research Database (Denmark)

Fuglede, Niels; Thomsen, Jon Juel

2016-01-01

An exact and approximate kinematic analysis of a roller chain drive modeled as a four-bar mechanism is presented. The span connects the sprockets such that they rotate in the same direction, and the sprocket size, number of teeth, and shaft center distance can be arbitrary. The driven sprocket...... to be very good agreement. All together this gives new insights into the characteristics of chain drive kinematics and the influence of main design parameters....

The effects of perceived leisure constraints among Korean university students

Science.gov (United States)

Sae-Sook Oh; Sei-Yi Oh; Linda L. Caldwell

2002-01-01

This study is based on Crawford, Jackson, and Godbey's model of leisure constraints (1991), and examines the relationships between the influences of perceived constraints, frequency of participation, and health status in the context of leisure-time outdoor activities. The study was based on a sample of 234 Korean university students. This study provides further...

pynoddy 1.0: an experimental platform for automated 3-D kinematic and potential field modelling

Science.gov (United States)

Florian Wellmann, J.; Thiele, Sam T.; Lindsay, Mark D.; Jessell, Mark W.

2016-03-01

We present a novel methodology for performing experiments with subsurface structural models using a set of flexible and extensible Python modules. We utilize the ability of kinematic modelling techniques to describe major deformational, tectonic, and magmatic events at low computational cost to develop experiments testing the interactions between multiple kinematic events, effect of uncertainty regarding event timing, and kinematic properties. These tests are simple to implement and perform, as they are automated within the Python scripting language, allowing the encapsulation of entire kinematic experiments within high-level class definitions and fully reproducible results. In addition, we provide a link to geophysical potential-field simulations to evaluate the effect of parameter uncertainties on maps of gravity and magnetics. We provide relevant fundamental information on kinematic modelling and our implementation, and showcase the application of our novel methods to investigate the interaction of multiple tectonic events on a pre-defined stratigraphy, the effect of changing kinematic parameters on simulated geophysical potential fields, and the distribution of uncertain areas in a full 3-D kinematic model, based on estimated uncertainties in kinematic input parameters. Additional possibilities for linking kinematic modelling to subsequent process simulations are discussed, as well as additional aspects of future research. Our modules are freely available on github, including documentation and tutorial examples, and we encourage the contribution to this project.