WorldWideScience

Sample records for switching locomotives

  1. 49 CFR 231.30 - Locomotives used in switching service.

    Science.gov (United States)

    2010-10-01

    ... classification of cars according to commodity or destination; assembling of cars for train movements; changing... locomotives built after March 31, 1977. (5) Material. (i) Steel or other material of equivalent or better... March 31, 1977, each vertical handhold must— (i) Be constructed of wrought iron, steel or other material...

  2. Locomotion

    DEFF Research Database (Denmark)

    Kiehn, Ole; Dougherty, Kimberly

    2016-01-01

    Locomotion is a complex motor behavior needed by animals and humans to move through the environment. All forms of locomotion, including swimming, flying, walking, running, and hopping, are repetitive motor activities that require the activation of the limb and body muscles in an organized rhythm ...

  3. Common mechanics of mode switching in locomotion of limbless and legged animals

    Science.gov (United States)

    Kuroda, Shigeru; Kunita, Itsuki; Tanaka, Yoshimi; Ishiguro, Akio; Kobayashi, Ryo; Nakagaki, Toshiyuki

    2014-01-01

    Crawling using muscular waves is observed in many species, including planaria, leeches, nemertea, aplysia, snails, chitons, earthworms and maggots. Contraction or extension waves propagate along the antero-posterior axis of the body as the crawler pushes the ground substratum backward. However, the observation that locomotory waves can be directed forward or backward has attracted much attention over the past hundred years. Legged organisms such as centipedes and millipedes exhibit parallel phenomena; leg tips form density waves that propagate backward or forward. Mechanical considerations reveal that leg-density waves play a similar role to locomotory waves in limbless species, and that locomotory waves are used by a mechanism common to both legged and limbless species to achieve crawling. Here, we report that both mode switching of the wave direction and friction control were achieved when backward motion was induced in the laboratory. We show that the many variations of switching in different animals can essentially be classified in two types according to mechanical considerations. We propose that during their evolution, limbless crawlers first moved in a manner similar to walking before legs were obtained. Therefore, legged crawlers might have learned the mechanical mode of movement involved in walking long before obtaining legs. PMID:24718452

  4. A longitudinal study of Caenorhabditis elegans larvae reveals a novel locomotion switch, regulated by Gαs signaling

    Science.gov (United States)

    Nagy, Stanislav; Wright, Charles; Tramm, Nora; Labello, Nicholas; Burov, Stanislav; Biron, David

    2013-01-01

    Despite their simplicity, longitudinal studies of invertebrate models are rare. We thus sought to characterize behavioral trends of Caenorhabditis elegans, from the mid fourth larval stage through the mid young adult stage. We found that, outside of lethargus, animals exhibited abrupt switching between two distinct behavioral states: active wakefulness and quiet wakefulness. The durations of epochs of active wakefulness exhibited non-Poisson statistics. Increased Gαs signaling stabilized the active wakefulness state before, during and after lethargus. In contrast, decreased Gαs signaling, decreased neuropeptide release, or decreased CREB activity destabilized active wakefulness outside of, but not during, lethargus. Taken together, our findings support a model in which protein kinase A (PKA) stabilizes active wakefulness, at least in part through two of its downstream targets: neuropeptide release and CREB. However, during lethargus, when active wakefulness is strongly suppressed, the native role of PKA signaling in modulating locomotion and quiescence may be minor. DOI: http://dx.doi.org/10.7554/eLife.00782.001 PMID:23840929

  5. Hybrid Locomotive for Energy Savings and Reduced Emissions

    Science.gov (United States)

    2017-08-01

    Norfolk Southern Corporation (NS) and Pennsylvania State University tested several different battery systems in hybrid locomotives. Advanced lithium-ion battery technology was the only kind that displayed the capacity to perform in heavy switching or...

  6. Locomotive Syndrome: Definition and Management

    OpenAIRE

    Nakamura, Kozo; Ogata, Toru

    2016-01-01

    Locomotive syndrome is a condition of reduced mobility due to impairment of locomotive organs. Since upright bipedal walking involves minutely controlled movement patterns, impairment of any aspect of the locomotive organs has the potential to adversely affect it. In addition to trauma, chronic diseases of the locomotive organs, which progress with repeated bouts of acute exacerbations, are common causes of the locomotive syndrome. In Japan?s super-aging society, many people are likely to exp...

  7. Models of Snail Locomotion

    Science.gov (United States)

    Chan, Brian; Hosoi, Anette

    2003-11-01

    All snails move over a thin layer of mucus using periodic deformations of their muscular foot. This unusual mode of locomotion can be modeled as a thin film of viscous fluid sandwiched between a flexible membrane and a rigid substrate. We present theoretical, numerical and experimental studies of locomotion via viscous stresses generated in thin films. Study of snail locomotion led us to design and construct several mechanical models: RoboSnail 1 which mimics snail locomotion incorrectly, but still proves to be a valid propulsion device over a thin viscous fluid layer and RoboSnail 2 which mimics land snails and uses forward-propagating compression waves on the base of the foot. Experimental results from the prototype machines are compared with long wavelength numerical and theoretical models.

  8. Compensations during Unsteady Locomotion.

    Science.gov (United States)

    Qiao, Mu; Jindrich, Devin L

    2014-12-01

    Locomotion in a complex environment is often not steady, but the mechanisms used by animals to power and control unsteady locomotion (stability and maneuverability) are not well understood. We use behavioral, morphological, and impulsive perturbations to determine the compensations used during unsteady locomotion. At the level both of the whole-body and of joints, quasi-stiffness models are useful for describing adjustments to the functioning of legs and joints during maneuvers. However, alterations to the mechanics of legs and joints often are distinct for different phases of the step cycle or for specific joints. For example, negotiating steps involves independent changes of leg stiffness during compression and thrust phases of stance. Unsteady locomotion also involves parameters that are not part of the simplest reduced-parameter models of locomotion (e.g., the spring-loaded inverted pendulum) such as moments of the hip joint. Extensive coupling among translational and rotational parameters must be taken into account to stabilize locomotion or maneuver. For example, maneuvers with morphological perturbations (increased rotational inertial turns) involve changes to several aspects of movement, including the initial conditions of rotation and ground-reaction forces. Coupled changes to several parameters may be employed to control maneuvers on a trial-by-trial basis. Compensating for increased rotational inertia of the body during turns is facilitated by the opposing effects of several mechanical and behavioral parameters. However, the specific rules used by animals to control translation and rotation of the body to maintain stability or maneuver have not been fully characterized. We initiated direct-perturbation experiments to investigate the strategies used by humans to maintain stability following center-of-mass (COM) perturbations. When walking, humans showed more resistance to medio-lateral perturbations (lower COM displacement). However, when running, humans

  9. AN ANALYTICAL STUDY OF SWITCHING TRACTION MOTORS

    Directory of Open Access Journals (Sweden)

    V. M. Bezruchenko

    2010-03-01

    Full Text Available The analytical study of switching of the tractive engines of electric locomotives is conducted. It is found that the obtained curves of change of current of the sections commuted correspond to the theory of average rectilinear switching. By means of the proposed method it is possible on the stage of design of tractive engines to forecast the quality of switching and to correct it timely.

  10. Locomotive Syndrome: Definition and Management.

    Science.gov (United States)

    Nakamura, Kozo; Ogata, Toru

    Locomotive syndrome is a condition of reduced mobility due to impairment of locomotive organs. Since upright bipedal walking involves minutely controlled movement patterns, impairment of any aspect of the locomotive organs has the potential to adversely affect it. In addition to trauma, chronic diseases of the locomotive organs, which progress with repeated bouts of acute exacerbations, are common causes of the locomotive syndrome. In Japan's super-aging society, many people are likely to experience locomotive syndrome in the later part of their lives. Exercise intervention is effective in improving motor function, but because the subjects are elderly people with significant degenerative diseases of the locomotor organs, caution should be taken in choosing the type and intensity of exercise. The present review discusses the definition, current burden, diagnosis and interventions pertaining to the locomotive syndrome. The concept and measures are spreading throughout Japan as one of the national health policy targets.

  11. Vibroacoustic characteristics of mine locomotives

    Energy Technology Data Exchange (ETDEWEB)

    Chigirinskii, S.E.; Ponomarev, N.S.; Leiman, Ya.A.

    1982-11-01

    The paper discusses noise pollution caused by locomotives used for mine haulage in underground mining. Noise pollution in a mine working and at the driver working place is measured. Mechanical vibrations of the floor in the driver cab are also determined. Noise pollution and mechanical vibrations of 3 locomotive types are comparatively evaluated: the AM-8D electric locomotive, the GR-4 inertia-type locomotive and the 1D-8 diesel locomotive. The results of investigations are shown in 2 tables. The inertia-type locomotive causes the most intensive noise pollution. Noise pollution of the diesel locomotive has been successfully suppressed by a system of shock absorbers. The following methods for noise and vibration control are discussed: use of soundproof cabs, damping vibrations at the driver's seat, use of motors with noise abatement systems and shock absorbers. (In Russian)

  12. Switched Systems With Multiple Invariant Sets

    Science.gov (United States)

    2015-05-06

    larger superset. We show the effectiveness of the dwell-time conditions by using examples of switching limit cycles commonly found in robotic locomotion ...commonly found in robotic locomotion and apping ight. 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT Same as Report...1 −1 1 −1 ]( x y ) + ( 2 −2 ) . This is a simplified version of (1), a central pattern generator used for control of swimming [12] or flying robots [2

  13. Advanced robot locomotion.

    Energy Technology Data Exchange (ETDEWEB)

    Neely, Jason C.; Sturgis, Beverly Rainwater; Byrne, Raymond Harry; Feddema, John Todd; Spletzer, Barry Louis; Rose, Scott E.; Novick, David Keith; Wilson, David Gerald; Buerger, Stephen P.

    2007-01-01

    This report contains the results of a research effort on advanced robot locomotion. The majority of this work focuses on walking robots. Walking robot applications include delivery of special payloads to unique locations that require human locomotion to exo-skeleton human assistance applications. A walking robot could step over obstacles and move through narrow openings that a wheeled or tracked vehicle could not overcome. It could pick up and manipulate objects in ways that a standard robot gripper could not. Most importantly, a walking robot would be able to rapidly perform these tasks through an intuitive user interface that mimics natural human motion. The largest obstacle arises in emulating stability and balance control naturally present in humans but needed for bipedal locomotion in a robot. A tracked robot is bulky and limited, but a wide wheel base assures passive stability. Human bipedal motion is so common that it is taken for granted, but bipedal motion requires active balance and stability control for which the analysis is non-trivial. This report contains an extensive literature study on the state-of-the-art of legged robotics, and it additionally provides the analysis, simulation, and hardware verification of two variants of a proto-type leg design.

  14. Steam Locomotives: a forgotten era

    African Journals Online (AJOL)

    The boiler was not armoured as the idea was that it was bullet proof. The locomotives were arranged into groups of five and for each group there was an engine as standby. As far as can be ascertained, locomotive No 537 was never armoured, but did work draw trains and freight trains during the Anglo-Boer War too.

  15. Synthesis of digital locomotive receiver of automatic locomotive signaling

    Directory of Open Access Journals (Sweden)

    K. V. Goncharov

    2013-02-01

    Full Text Available Purpose. Automatic locomotive signaling of continuous type with a numeric coding (ALSN has several disadvantages: a small number of signal indications, low noise stability, high inertia and low functional flexibility. Search for new and more advanced methods of signal processing for automatic locomotive signaling, synthesis of the noise proof digital locomotive receiver are essential. Methodology. The proposed algorithm of detection and identification locomotive signaling codes is based on the definition of mutual correlations of received oscillation and reference signals. For selecting threshold levels of decision element the following criterion has been formulated: the locomotive receiver should maximum set the correct solution for a given probability of dangerous errors. Findings. It has been found that the random nature of the ALSN signal amplitude does not affect the detection algorithm. However, the distribution law and numeric characteristics of signal amplitude affect the probability of errors, and should be considered when selecting a threshold levels According to obtained algorithm of detection and identification ALSN signals the digital locomotive receiver has been synthesized. It contains band pass filter, peak limiter, normalizing amplifier with automatic gain control circuit, analog to digital converter and digital signal processor. Originality. The ALSN system is improved by the way of the transfer of technical means to modern microelectronic element base, more perfect methods of detection and identification codes of locomotive signaling are applied. Practical value. Use of digital technology in the construction of the locomotive receiver ALSN will expand its functionality, will increase the noise immunity and operation stability of the locomotive signal system in conditions of various destabilizing factors.

  16. Artificial locomotion control

    DEFF Research Database (Denmark)

    Azevedo, Christine; Poignet, Philippe; Espiau, Bernard

    2004-01-01

    This paper concerns the simultaneous synthesis and control of walking gaits for biped robots. The goal is to propose an adaptable and reactive control law for two-legged machines. The problem is addressed with human locomotion as a reference. The starting point of our work is an analysis of human...... walking from descriptive (biomechanics) as well as explicative (neuroscience and physiology) points of view, the objective being to stress the relevant elements for the approach of robot control. The adopted principles are then: no joint trajectory tracking; explicit distinction and integration...... of postural and walking control; use of evolutive optimization objectives; on-line event handling and environment adaptation and anticipation. This leads to the synthesis of an original control scheme based on non-linear model predictive control: Trajectory Free NMPC. The movement is specified implicitly...

  17. Locomotion through Morphosis

    DEFF Research Database (Denmark)

    Larsen, Jørgen Christian

    construction kit called LocoKit, which is intended as a system on which studies on locomotion can be done in a simple way. The simplicity is ob- tained by giving the user the opportunity to build legged robots from a set of small components which allows for adjusting various parameters on the robot, even after...... in nature can be found and tested. These results shows the poten- tial of LocoKit and are nicely in line with the goal of the project. I future development, LocoKit will be improved in such a way that it allows the user to build even more efficient robots than have been build until now....

  18. Self-improving biped locomotion

    Science.gov (United States)

    Teixeira, C.; Costa, L.; Santos, C.

    2013-10-01

    An approach addressing biped locomotion is here introduced. Central Pattern Generators (CPGs) and Dynamic Movement Primitives (DMPs) were combined to easily produce complex trajectories for the joints of a simulated DARwIn-OP. Policy Learning by Weighting Exploration with the Returns (PoWER) was implemented to improve the robot's locomotion through variation of the DMP's parameters. Maximization of the DARwIn-OP's frontal velocity was addressed and results show a velocity improvement of 213%. The results are very promising and demonstrate the approach's flexibility at generating new trajectories for locomotion.

  19. Dedicated Hippocampal Inhibitory Networks for Locomotion and Immobility.

    Science.gov (United States)

    Arriaga, Moises; Han, Edward B

    2017-09-20

    and environments, suggesting there are separate dedicated circuits for processing information during locomotion and immobility. Understanding how the hippocampus switches between different network configurations may lead to therapeutic approaches to hippocampal-dependent dysfunctions, such as Alzheimer's disease or cognitive decline. Copyright © 2017 the authors 0270-6474/17/379222-17$15.00/0.

  20. Fundamentals of soft robot locomotion

    OpenAIRE

    Calisti, M.; Picardi, G.; Laschi, C.

    2017-01-01

    Soft robotics and its related technologies enable robot abilities in several robotics domains including, but not exclusively related to, manipulation, manufacturing, human���robot interaction and locomotion. Although field applications have emerged for soft manipulation and human���robot interaction, mobile soft robots appear to remain in the research stage, involving the somehow conflictual goals of having a deformable body and exerting forces on the environment to achieve locomotion. This p...

  1. Small-scale soft-bodied robot with multimodal locomotion

    Science.gov (United States)

    Hu, Wenqi; Lum, Guo Zhan; Mastrangeli, Massimo; Sitti, Metin

    2018-02-01

    Untethered small-scale (from several millimetres down to a few micrometres in all dimensions) robots that can non-invasively access confined, enclosed spaces may enable applications in microfactories such as the construction of tissue scaffolds by robotic assembly, in bioengineering such as single-cell manipulation and biosensing, and in healthcare such as targeted drug delivery and minimally invasive surgery. Existing small-scale robots, however, have very limited mobility because they are unable to negotiate obstacles and changes in texture or material in unstructured environments. Of these small-scale robots, soft robots have greater potential to realize high mobility via multimodal locomotion, because such machines have higher degrees of freedom than their rigid counterparts. Here we demonstrate magneto-elastic soft millimetre-scale robots that can swim inside and on the surface of liquids, climb liquid menisci, roll and walk on solid surfaces, jump over obstacles, and crawl within narrow tunnels. These robots can transit reversibly between different liquid and solid terrains, as well as switch between locomotive modes. They can additionally execute pick-and-place and cargo-release tasks. We also present theoretical models to explain how the robots move. Like the large-scale robots that can be used to study locomotion, these soft small-scale robots could be used to study soft-bodied locomotion produced by small organisms.

  2. Self-generated sounds of locomotion and ventilation and the evolution of human rhythmic abilities.

    Science.gov (United States)

    Larsson, Matz

    2014-01-01

    It has been suggested that the basic building blocks of music mimic sounds of moving humans, and because the brain was primed to exploit such sounds, they eventually became incorporated in human culture. However, that raises further questions. Why do genetically close, culturally well-developed apes lack musical abilities? Did our switch to bipedalism influence the origins of music? Four hypotheses are raised: (1) Human locomotion and ventilation can mask critical sounds in the environment. (2) Synchronization of locomotion reduces that problem. (3) Predictable sounds of locomotion may stimulate the evolution of synchronized behavior. (4) Bipedal gait and the associated sounds of locomotion influenced the evolution of human rhythmic abilities. Theoretical models and research data suggest that noise of locomotion and ventilation may mask critical auditory information. People often synchronize steps subconsciously. Human locomotion is likely to produce more predictable sounds than those of non-human primates. Predictable locomotion sounds may have improved our capacity of entrainment to external rhythms and to feel the beat in music. A sense of rhythm could aid the brain in distinguishing among sounds arising from discrete sources and also help individuals to synchronize their movements with one another. Synchronization of group movement may improve perception by providing periods of relative silence and by facilitating auditory processing. The adaptive value of such skills to early ancestors may have been keener detection of prey or stalkers and enhanced communication. Bipedal walking may have influenced the development of entrainment in humans and thereby the evolution of rhythmic abilities.

  3. Fundamentals of soft robot locomotion.

    Science.gov (United States)

    Calisti, M; Picardi, G; Laschi, C

    2017-05-01

    Soft robotics and its related technologies enable robot abilities in several robotics domains including, but not exclusively related to, manipulation, manufacturing, human-robot interaction and locomotion. Although field applications have emerged for soft manipulation and human-robot interaction, mobile soft robots appear to remain in the research stage, involving the somehow conflictual goals of having a deformable body and exerting forces on the environment to achieve locomotion. This paper aims to provide a reference guide for researchers approaching mobile soft robotics, to describe the underlying principles of soft robot locomotion with its pros and cons, and to envisage applications and further developments for mobile soft robotics. © 2017 The Author(s).

  4. Relation between observed locomotion traits and locomotion score in dairy cows

    NARCIS (Netherlands)

    Schlageter Tello, A.A.; Bokkers, E.A.M.; Groot Koerkamp, P.W.G.; Hertem, van T.; Viazzi, S.; Lokhorst, Kees

    2015-01-01

    Lameness is still an important problem in modern dairy farming. Human observation of locomotion, by looking at different traits in one go, is used in practice to assess locomotion. The objectives of this article were to determine which individual locomotion traits are most related to locomotion

  5. In Pipe Robot with Hybrid Locomotion System

    Directory of Open Access Journals (Sweden)

    Cristian Miclauş

    2015-06-01

    Full Text Available The first part of the paper covers aspects concerning in pipe robots and their components, such as hybrid locomotion systems and the adapting mechanisms used. The second part describes the inspection robot that was developed, which combines tracked and wheeled locomotion (hybrid locomotion. The end of the paper presents the advantages and disadvantages of the proposed robot.

  6. Locomotive monitoring system using wireless sensor networks

    CSIR Research Space (South Africa)

    Croucamp, PL

    2014-07-01

    Full Text Available Theft of cables used for powering a locomotive not only stops the train from functioning but also paralyzes the signalling and monitoring system. This means that information on certain locomotive's cannot be passed onto other locomotives which may...

  7. Pseudospark switches

    International Nuclear Information System (INIS)

    Billault, P.; Riege, H.; Gulik, M. van; Boggasch, E.; Frank, K.

    1987-01-01

    The pseudospark discharge is bound to a geometrical structure which is particularly well suited for switching high currents and voltages at high power levels. This type of discharge offers the potential for improvement in essentially all areas of switching operation: peak current and current density, current rise, stand-off voltage, reverse current capability, cathode life, and forward drop. The first pseudospark switch was built at CERN at 1981. Since then, the basic switching characteristics of pseudospark chambers have been studied in detail. The main feature of a pseudospark switch is the confinement of the discharge plasma to the device axis. The current transition to the hollow electrodes is spread over a rather large surface area. Another essential feature is the easy and precise triggering of the pseudospark switch from the interior of the hollow electrodes, relatively far from the main discharge gap. Nanosecond delay and jitter values can be achieved with trigger energies of less than 0.1 mJ, although cathode heating is not required. Pseudospark gaps may cover a wide range of high-voltage, high-current, and high-pulse-power switching at repetition rates of many kilohertz. This report reviews the basic researh on pseudospark switches which has been going on at CERN. So far, applications have been developed in the range of thyratron-like medium-power switches at typically 20 to 40 kV and 0.5 to 10 kA. High-current pseudospark switches have been built for a high-power 20 kJ pulse generator which is being used for long-term tests of plasma lenses developed for the future CERN Antiproton Collector (ACOL). The high-current switches have operated for several hundred thousand shots, with 20 to 50 ns jitter at 16 kV charging voltage and more than 100 kA peak current amplitude. (orig.)

  8. Switching antidepressants

    African Journals Online (AJOL)

    depressive disorder, with response rates of 50-60%. Switching within or between classes of antidepressants is often required in patients with an insufficient response to SSRIs.12 Because they share a similar mechanism of action, the immediate substitution of one SSRI for another is probably the easiest switching option.

  9. Nigral Glutamatergic Neurons Control the Speed of Locomotion.

    Science.gov (United States)

    Ryczko, Dimitri; Grätsch, Swantje; Schläger, Laura; Keuyalian, Avo; Boukhatem, Zakaria; Garcia, Claudia; Auclair, François; Büschges, Ansgar; Dubuc, Réjean

    2017-10-04

    The mesencephalic locomotor region (MLR) plays a crucial role in locomotor control. In vertebrates, stimulation of the MLR at increasing intensities elicits locomotion of growing speed. This effect has been presumed to result from higher brain inputs activating the MLR like a dimmer switch. Here, we show in lampreys ( Petromyzon marinus ) of either sex that incremental stimulation of a region homologous to the mammalian substantia nigra pars compacta (SNc) evokes increasing activation of MLR cells with a graded increase in the frequency of locomotor movements. Neurons co-storing glutamate and dopamine were found to project from the primal SNc to the MLR. Blockade of glutamatergic transmission largely diminished MLR cell responses and locomotion. Local blockade of D 1 receptors in the MLR decreased locomotor frequency, but did not disrupt the SNc-evoked graded control of locomotion. Our findings revealed the presence of a glutamatergic input to the MLR originating from the primal SNc that evokes graded locomotor movements. SIGNIFICANCE STATEMENT The mesencephalic locomotor region (MLR) plays a crucial role in the control of locomotion. It projects downward to reticulospinal neurons that in turn activate the spinal locomotor networks. Increasing the intensity of MLR stimulation produces a growing activation of reticulospinal cells and a progressive increase in the speed of locomotor movements. Since the discovery of the MLR some 50 years ago, it has been presumed that higher brain regions activate the MLR in a graded fashion, but this has not been confirmed yet. Here, using a combination of techniques from cell to behavior, we provide evidence of a new glutamatergic pathway activating the MLR in a graded fashion, and consequently evoking a progressive increase in locomotor output. Copyright © 2017 the authors 0270-6474/17/379759-12$15.00/0.

  10. Analysis of Hexapod Robot Locomotion

    Directory of Open Access Journals (Sweden)

    Tomas Luneckas

    2011-03-01

    Full Text Available Hexapod robot locomotion is analyzed. Trajectory forming method for one leg is introduced. Servo angles are expressed using geometric inverse kinematics method. Forming of tripod gait is described and a diagram representing it is presented. Servo control parameters are defined to ensure fluent and versatile robot control. Several servo control methods are presented. After testing robot movement using different servo control methods, gait generation is corrected and control method that meets servo control parameters is chosen.Article in Lithuanian

  11. Scaling laws of aquatic locomotion

    Science.gov (United States)

    Sun, BoHua

    2017-10-01

    In recent years studies of aquatic locomotion have provided some remarkable insights into the many features of fish swimming performances. This paper derives a scaling relation of aquatic locomotion C D( Re)2 = ( Sw)2 and its corresponding log law and power law. For power scaling law, ( Sw)2 = β n Re 2-1/ n , which is valid within the full spectrum of the Reynolds number Re = UL/ν from low up to high, can simply be expressed as the power law of the Reynolds number Re and the swimming number Sw = ωAL/ν as Re ∝ ( Sw)σ, with σ = 2 for creeping flows, σ = 4=3 for laminar flows, σ = 10=9 and σ = 14=13 for turbulent flows. For log law this paper has derived the scaling law as Sw ∝ Re=(ln Re+1:287), which is even valid for a much wider range of the Reynolds number Re. Both power and log scaling relationships link the locomotory input variables that describe the swimmer's gait A; ω via the swimming number Sw to the locomotory output velocity U via the longitudinal Reynolds number Re, and reveal the secret input-output relationship of aquatic locomotion at different scales of the Reynolds number

  12. Emotion through locomotion: gender impact.

    Directory of Open Access Journals (Sweden)

    Samuel Krüger

    Full Text Available Body language reading is of significance for daily life social cognition and successful social interaction, and constitutes a core component of social competence. Yet it is unclear whether our ability for body language reading is gender specific. In the present work, female and male observers had to visually recognize emotions through point-light human locomotion performed by female and male actors with different emotional expressions. For subtle emotional expressions only, males surpass females in recognition accuracy and readiness to respond to happy walking portrayed by female actors, whereas females exhibit a tendency to be better in recognition of hostile angry locomotion expressed by male actors. In contrast to widespread beliefs about female superiority in social cognition, the findings suggest that gender effects in recognition of emotions from human locomotion are modulated by emotional content of actions and opposite actor gender. In a nutshell, the study makes a further step in elucidation of gender impact on body language reading and on neurodevelopmental and psychiatric deficits in visual social cognition.

  13. Magnetic switching

    International Nuclear Information System (INIS)

    Kirbie, H.C.

    1989-01-01

    Magnetic switching is a pulse compression technique that uses a saturable inductor (reactor) to pass pulses of energy between two capacitors. A high degree of pulse compression can be achieved in a network when several of these simple, magnetically switched circuits are connected in series. Individual inductors are designed to saturate in cascade as a pulse moves along the network. The technique is particularly useful when a single-pulse network must be very reliable or when a multi-pulse network must operate at a high pulse repetition frequency (PRF). Today, magnetic switches trigger spark gaps, sharpen the risetimes of high energy pulses, power large lasers, and drive high PRF linear induction accelerators. This paper will describe the technique of magnetic pulse compression using simple networks and design equations. A brief review of modern magnetic materials and of their role in magnetic switch design will be presented. 12 refs., 8 figs

  14. Locomotive biofuel study : preliminary study on the use and the effects of biodiesel in locomotives.

    Science.gov (United States)

    2014-05-01

    Section 404 of the Passenger Rail Investment and Improvement Act (PRIIA), 2008, mandated that the Federal Railroad : Administration (FRA) undertake a Locomotive Biofuel Study to investigate the feasibility of using biofuel blends as locomotive : engi...

  15. Characteristics of undulatory locomotion in granular media

    OpenAIRE

    Peng, Zhiwei; Pak, On Shun; Elfring, Gwynn J.

    2015-01-01

    Undulatory locomotion is ubiquitous in nature and observed in different media, from the swimming of flagellated microorganisms in biological fluids, to the slithering of snakes on land, or the locomotion of sandfish lizards in sand. Despite the similarity in the undulating pattern, the swimming characteristics depend on the rheological properties of different media. Analysis of locomotion in granular materials is relatively less developed compared with fluids partially due to a lack of valida...

  16. Coupling of cytoskeleton functions for fibroblast locomotion

    DEFF Research Database (Denmark)

    Couchman, J R; Lenn, M; Rees, D A

    1985-01-01

    Using a chick cell phenotype specialised for locomotion with morphometric measurements made possible by modern instrumentation technology, we have reinvestigated motile functions in fibroblast locomotion. Quantitative analysis of rapid fluctuations in cell form and organelle distribution during l...... function of microtubules to direct the flow towards multiple foci on the leading edge, and so determine cell polarity. Such a mechanism of locomotion for fibroblasts has many features consistent with evidence for other cell types, especially amoebae and leukocytes....

  17. Modeling limbless locomotion using ADAMS software Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Limbless locomotion has the potential of meeting transportation requirements, particularly in challenging environments. Snakes can traverse a variety of surfaces...

  18. Railroad and locomotive technology roadmap.

    Energy Technology Data Exchange (ETDEWEB)

    Stodolsky, F.; Gaines, L.; Energy Systems

    2003-02-24

    Railroads are important to the U.S. economy. They transport freight efficiently, requiring less energy and emitting fewer pollutants than other modes of surface transportation. While the railroad industry has steadily improved its fuel efficiency--by 16% over the last decade--more can, and needs to, be done. The ability of locomotive manufacturers to conduct research into fuel efficiency and emissions reduction is limited by the small number of locomotives manufactured annually. Each year for the last five years, the two North American locomotive manufacturers--General Electric Transportation Systems and the Electro-Motive Division of General Motors--have together sold about 800 locomotives in the United States. With such a small number of units over which research costs can be spread, outside help is needed to investigate all possible ways to reduce fuel usage and emissions. Because fuel costs represent a significant portion of the total operating costs of a railroad, fuel efficiency has always been an important factor in the design of locomotives and in the operations of a railroad. However, fuel efficiency has recently become even more critical with the introduction of strict emission standards by the U.S. Environmental Protection Agency, to be implemented in stages (Tiers 0, 1, and 2) between 2000 and 2005. Some of the technologies that could be employed to meet the emission standards may negatively affect fuel economy--by as much as 10-15% when emissions are reduced to Tier 1 levels. Lowering fuel economy by that magnitude would have a serious impact on the cost to the consumer of goods shipped by rail, on the competitiveness of the railroad industry, and on this country's dependence on foreign oil. Clearly, a joint government/industry R&D program is needed to help catalyze the development of advanced technologies that will substantially reduce locomotive engine emissions while also improving train system energy efficiency. DOE convened an industry

  19. The investigation of the locomotive boiler material

    International Nuclear Information System (INIS)

    Tucholski, Z.; Wasiak, J.; Bilous, W.; Hajewska, E.

    2006-01-01

    In the paper, the history of narrow-gauge railway system is described. The other information about the steam locomotive construction, as well as the technical regulations of its construction and exploitation are also done. The results of the studies of the locomotive boiler material are presented. (authors)

  20. 77 FR 21311 - Locomotive Safety Standards

    Science.gov (United States)

    2012-04-09

    ... final rule incorporates existing industry and engineering best practices related to locomotives and... retrospective review requirements of E.O. 13563, trends in locomotive operation, concern about the safe design... sub-assemblies of pneumatic valves, electronic controls and software (referred to as line replaceable...

  1. Continuum limbed robots for locomotion

    Science.gov (United States)

    Mutlu, Alper

    This thesis focuses on continuum robots based on pneumatic muscle technology. We introduce a novel approach to use these muscles as limbs of lightweight legged robots. The flexibility of the continuum legs of these robots offers the potential to perform some duties that are not possible with classical rigid-link robots. Potential applications are as space robots in low gravity, and as cave explorer robots. The thesis covers the fabrication process of continuum pneumatic muscles and limbs. It also provides some new experimental data on this technology. Afterwards, the designs of two different novel continuum robots - one tripod, one quadruped - are introduced. Experimental data from tests using the robots is provided. The experimental results are the first published example of locomotion with tripod and quadruped continuum legged robots. Finally, discussion of the results and how far this technology can go forward is presented.

  2. Locomotive track detection for underground

    Science.gov (United States)

    Ma, Zhonglei; Lang, Wenhui; Li, Xiaoming; Wei, Xing

    2017-08-01

    In order to improve the PC-based track detection system, this paper proposes a method to detect linear track for underground locomotive based on DSP + FPGA. Firstly, the analog signal outputted from the camera is sampled by A / D chip. Then the collected digital signal is preprocessed by FPGA. Secondly, the output signal of FPGA is transmitted to DSP via EMIF port. Subsequently, the adaptive threshold edge detection, polar angle and radius constrain based Hough transform are implemented by DSP. Lastly, the detected track information is transmitted to host computer through Ethernet interface. The experimental results show that the system can not only meet the requirements of real-time detection, but also has good robustness.

  3. Dynamic similarity in granular locomotion

    Science.gov (United States)

    Kamrin, Ken; Slonaker, James; Zhang, Qiong

    2017-11-01

    To model the flow of granular media with high accuracy, a number of subtleties arise and complex constitutive relations are needed to address them. However, making certain rheological simplifications produces a framework that is simple enough to obtain global rule-sets that can be used to aid in design without having to solve any partial differential equations or perform discrete element simulations. This talk will show how reduced-order rule-sets such as the Resistive Force Theory can be obtained from a basic frictional plasticity model, and how plasticity can further be used to produce a family of scaling laws in granular locomotion reminiscent of `wind tunnel' scaling laws in fluid dynamics. These are verified with experiments and numerical simulations.

  4. Mechanisms of Protrusion and Cell Locomotion

    Science.gov (United States)

    Keller, Hansuli

    Earlier models explaining cell locomotion are briefly reviewed. Then, a model explaining locomotion of non-adhesive Walker carcinosarcoma cells is proposed based on the following data: 1) Walker carcinosarcoma cells, which normally form lamellipodia, can produce forces for movement by at least two distinct actin-based mechanisms, 2) Lamellipodial motility is driven by local actin polymerization, but lamellipodia and actin-based mechanisms (polymerization or contraction) at the front are redundant for locomotion, 3) actomyosin-dependent contraction at the rear (body and/or uropod) is sufficient and necessary for locomotion, 4) fluid pressure can generate protrusion (blebs), 5) an intact cortical layer at the front tends to reduce the speed of locomotion, 6) there is no biologically significant difference in the efficiency of locomotion (speed, persistence, net displacement) of migrating cells showing either lamellipodia, blebs or no morphologically recognizable protrusions, 7) polymerized actin is concentrated in the cortical actin layer. Myosin IIA is preferentially associated with the actin cortex at the rear part of the cell. The data suggest that actomyosin-based contraction in the form of cortical contraction generates protrusion and locomotion in Walker carcinosarcoma cells as previously described in Amoebae. The role of actomyosin-dependent contraction and of fluid-driven mechanisms in other metazoan tissue cell lines is discussed.

  5. 49 CFR 230.21 - Steam locomotive number change.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Steam locomotive number change. 230.21 Section 230... Recordkeeping Requirements § 230.21 Steam locomotive number change. When a steam locomotive number is changed, the steam locomotive owner and/or operator must reflect the change in the upper right-hand corner of...

  6. Performance of raters to assess locomotion in dairy cattle

    NARCIS (Netherlands)

    Schlageter Tello, A.A.

    2015-01-01

    Abstract Locomotion scoring systems are procedures used to evaluate the quality of cows’ locomotion. When scoring locomotion, raters focus their attention on gait and posture traits that are described in the protocol. Using these traits, raters assign a locomotion score to

  7. 49 CFR 229.121 - Locomotive cab noise.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Locomotive cab noise. 229.121 Section 229.121... § 229.121 Locomotive cab noise. (a) Performance standards for locomotives. (1) When tested for static noise in accordance with paragraph (a)(3) of this section, all locomotives of each design or model that...

  8. Locomotive Assignment Problem with Heterogeneous Vehicle Fleet and Hiring External Locomotives

    Directory of Open Access Journals (Sweden)

    Dušan Teichmann

    2015-01-01

    Full Text Available This paper focuses on solving the problem of how to assign locomotives to assembled trains optimally. To solve the problem, linear programming is applied. The situation we model in the paper occurs in the conditions of a transport operator that provides rail transport in the Czech Republic. In the paper, an extended locomotive assignment problem is modeled; the transport operator can use different classes of the locomotives to serve individual connections, some connections must be served by a predefined locomotive class, and the locomotives can be allocated to several depots at the beginning. The proposed model also takes into consideration the fact that some connections can be served by the locomotives of external transport companies or operators. The presented model is applied to a real example in order to test its functionality.

  9. Modeling limbless locomotion using ADAMS software

    Data.gov (United States)

    National Aeronautics and Space Administration — Until now, the methods used by probes or humans for locomotion on planetary surfaces have typically been restricted to variations of wheeled motion. As human...

  10. Locomotive to Automobile Baseline Crash Tests

    Science.gov (United States)

    1975-08-01

    Four Locomotive to Automobile Crash tests were performed by the Dynamic Science Division of Ultrasystems at DOT's High Speed Ground Test Center under contract to the Transportation Systems Center, which is conducting the work for the Federal Railroad...

  11. Issues in Locomotive Crew Management and Scheduling

    Science.gov (United States)

    1990-11-01

    This study explores matters related to the scheduling and management of locomotive crews, particularly as they : might contribute to fatigue and stress. It describes how crews are scheduled currently, why there is so much : unpredictability in schedu...

  12. Development of Underwater Microrobot with Biomimetic Locomotion

    Directory of Open Access Journals (Sweden)

    W. Zhang

    2006-01-01

    Full Text Available Microrobots have powerful applications in biomedical and naval fields. They should have a compact structure, be easy to manufacture, have efficient locomotion, be driven by low voltage and have a simple control system. To meet these purposes, inspired by the leg of stick insects, we designed a novel type of microrobot with biomimetic locomotion with 1-DOF (degree of freedom legs. The locomotion includes two ionic conducting polymer film (ICPF actuators to realize the 2-DOF motion. We developed several microrobots with this locomotion. Firstly, we review a microrobot, named Walker-1, with 1-DOF motion. And then a new microrobot, named Walker-2, utilizing six ICPF actuators, with 3-DOF motion is introduced. It is 47 mm in diameter and 8 mm in height (in static state. It has 0.61 g of dried weight. We compared the two microrobot prototypes, and the result shows that Walker-2 has some advantages, such as more flexible moving motion, good balance, less water resistance, more load-carrying ability and so on. We also compared it with some insect-inspired microrobots and some microrobots with 1-DOF legs, and the result shows that a microrobot with this novel type of locomotion has some advantages. Its structure has fewer actuators and joints, a simpler control system and is compact. The ICPF actuator decides that it can be driven by low voltage (less than 5 V and move in water. A microrobot with this locomotion has powerful applications in biomedical and naval fields.

  13. Characterization of undulatory locomotion in granular media

    Science.gov (United States)

    Peng, Zhiwei; Pak, On Shun; Elfring, Gwynn

    2015-11-01

    Undulatory locomotion is ubiquitous in nature, from the swimming of flagellated microorganisms in biological fluids, to the slithering of snakes on land, or the locomotion of sandfish lizards in sand. Analysis of locomotion in granular materials is relatively less developed compared with fluids partially due to a lack of validated force models but a recently proposed resistive force theory (RFT) in granular media has been shown useful in studying the locomotion of a sand-swimming lizard. Here we employ this model to investigate the swimming characteristics of an undulating slender filament of both finite and infinite length. For infinite swimmers, similar to results in viscous fluids, the sawtooth waveform is found to be optimal for propulsion speed at a given power consumption. We also compare the swimming characteristics of sinusoidal and sawtooth swimmers with swimming in viscous fluids. More complex swimming dynamics emerge when the assumption of an infinite swimmer is removed. In particular, we characterize the effects of drifting and pitching in terms of propulsion speed and efficiency for a finite sinusoidal swimmer. The results complement our understanding of undulatory locomotion and provide insights into the effective design of locomotive systems in granular media.

  14. Characteristics of undulatory locomotion in granular media

    Science.gov (United States)

    Peng, Zhiwei; Pak, On Shun; Elfring, Gwynn J.

    2016-03-01

    Undulatory locomotion is ubiquitous in nature and observed in different media, from the swimming of flagellated microorganisms in biological fluids, to the slithering of snakes on land, or the locomotion of sandfish lizards in sand. Despite the similarity in the undulating pattern, the swimming characteristics depend on the rheological properties of different media. Analysis of locomotion in granular materials is relatively less developed compared with fluids partially due to a lack of validated force models but recently a resistive force theory in granular media has been proposed and shown useful in studying the locomotion of a sand-swimming lizard. Here we employ the proposed model to investigate the swimming characteristics of a slender filament, of both finite and infinite length, undulating in a granular medium and compare the results with swimming in viscous fluids. In particular, we characterize the effects of drifting and pitching in terms of propulsion speed and efficiency for a finite sinusoidal swimmer. We also find that, similar to Lighthill's results using resistive force theory in viscous fluids, the sawtooth swimmer is the optimal waveform for propulsion speed at a given power consumption in granular media. The results complement our understanding of undulatory locomotion and provide insights into the effective design of locomotive systems in granular media.

  15. Push-Pull Locomotion for Vehicle Extrication

    Science.gov (United States)

    Creager, Colin M.; Johnson, Kyle A.; Plant, Mark; Moreland, Scott J.; Skonieczny, Krzysztof

    2014-01-01

    For applications in which unmanned vehicles must traverse unfamiliar terrain, there often exists the risk of vehicle entrapment. Typically, this risk can be reduced by using feedback from on-board sensors that assess the terrain. This work addressed the situations where a vehicle has already become immobilized or the desired route cannot be traversed using conventional rolling. Specifically, the focus was on using push-pull locomotion in high sinkage granular material. Push-pull locomotion is an alternative mode of travel that generates thrust through articulated motion, using vehicle components as anchors to push or pull against. It has been revealed through previous research that push-pull locomotion has the capacity for generating higher net traction forces than rolling, and a unique optical flow technique indicated that this is the result of a more efficient soil shearing method. It has now been found that pushpull locomotion results in less sinkage, lower travel reduction, and better power efficiency in high sinkage material as compared to rolling. Even when starting from an "entrapped" condition, push-pull locomotion was able to extricate the test vehicle. It is the authors' recommendation that push-pull locomotion be considered as a reliable back-up mode of travel for applications where terrain entrapment is a possibility.

  16. The dynamics of quadrupedal locomotion.

    Science.gov (United States)

    Pandy, M G; Kumar, V; Berme, N; Waldron, K J

    1988-08-01

    This paper presents a dynamical analysis of quadrupedal locomotion, with specific reference to an adult Nubian goat. Measurements of ground reaction forces and limb motion are used to assess variations in intersegmental forces, joint moments, and instantaneous power for three discernible gaits: walking, running, and jumping. In each case, inertial effects of the torso are shown to dominate to the extent that lower-extremity contributions may be considered negligible. Footforces generated by the forelimbs exceed those exerted by the hindlimbs; and, in general, ground reactions increase with speed. The shoulder and hip dominate mechanical energy production during walking, while the knee plays a more significant role in running. In both cases, however, the elbow absorbs energy, and by so doing functions primarily as a damping (control) element. As opposed to either walking or running, jumping requires total horizontal retardation of the body's center of mass. In this instance, generating the necessary vertical thrust amounts to energy absorption at all joints of the lower extremities.

  17. The PS locomotive runs again

    CERN Document Server

    2001-01-01

    Over forty years ago, the PS train entered service to steer the magnets of the accelerator into place... ... a service that was resumed last Tuesday. Left to right: Raymond Brown (CERN), Claude Tholomier (D.B.S.), Marcel Genolin (CERN), Gérard Saumade (D.B.S.), Ingo Ruehl (CERN), Olivier Carlier (D.B.S.), Patrick Poisot (D.B.S.), Christian Recour (D.B.S.). It is more than ten years since people at CERN heard the rumbling of the old PS train's steel wheels. Last Tuesday, the locomotive came back into service to be tested. It is nothing like the monstrous steel engines still running on conventional railways -just a small electric battery-driven vehicle employed on installing the magnets for the PS accelerator more than 40 years ago. To do so, it used the tracks that run round the accelerator. In fact, it is the grandfather of the LEP monorail. After PS was commissioned in 1959, the little train was used more and more rarely. This is because magnets never break down, or hardly ever! In fact, the loc...

  18. Robot locomotion on weak ground

    Science.gov (United States)

    Qian, Feifei; Li, Chen; Umbanhowar, Paul; Goldman, Daniel

    2012-11-01

    Natural substrates like sand, soil, and leaf litter vary widely in penetration resistance. Little is known about how animals (and increasingly robots) respond to this variation. To address this deficit, we built an air fluidized bed trackway, in which we control penetration resistance of 1mm granular substrates down to zero by increasing the upward flow rate, Q , to the fluidization transition. Using a 2 . 5 kg bio-inspired hexapedal robot as our model locomotor, we systematically study how locomotion performance (average forward speed, v) varies with penetration resistance, limb kinematics, and foot morphology. Average robot speed decreases with increasing Q, and decreases faster for robots with higher leg frequency or narrower leg width. A previously developed model, which captured the robot's performance on granular media with Q = 0 , also captures the observed performance for weakened states with Q > 0 . A single dimensionless control parameter from the model, which combines gait and ground parameters, determines v for all penetration resistances. Our ground control technique and modeling approach provide a way to probe and understand the limits of locomotor performance on yielding substrates.

  19. The Role of Adaptation in Body Load-Regulating Mechanisms During Locomotion

    Science.gov (United States)

    Ruttley, Tara; Holt, Christopher; Mulavara, Ajitkumar; Bloomberg, Jacob

    2010-01-01

    Body loading is a fundamental parameter that modulates motor output during locomotion, and is especially important for controlling the generation of stepping patterns, dynamic balance, and termination of locomotion. Load receptors that regulate and control posture and stance in locomotion include the Golgi tendon organs and muscle spindles at the hip, knee, and ankle joints, and the Ruffini endings and the Pacinian corpuscles in the soles of the feet. Increased body weight support (BWS) during locomotion results in an immediate reorganization of locomotor control, such as a reduction in stance and double support duration and decreased hip, ankle, and knee angles during the gait cycle. Previous studies on the effect during exposure to increased BWS while walking showed a reduction in lower limb joint angles and gait cycle timing that represents a reorganization of locomotor control. Until now, no studies have investigated how locomotor control responds after a period of exposure to adaptive modification in the body load sensing system. The goal of this research was to determine the adaptive properties of body load-regulating mechanisms in locomotor control during locomotion. We hypothesized that body load-regulating mechanisms contribute to locomotor control, and adaptive changes in these load-regulating mechanisms require reorganization to maintain forward locomotion. Head-torso coordination, lower limb movement patterns, and gait cycle timing were evaluated before and after a 30-minute adaptation session during which subjects walked on a treadmill at 5.4 km/hr with 40% body weight support (BWS). Before and after the adaptation period, head-torso and lower limb 3D kinematic data were obtained while performing a goal directed task during locomotion with 0% BWS using a video-based motion analysis system, and gait cycle timing parameters were collected by foot switches positioned under the heel and toe of the subjects shoes. Subjects showed adaptive modification in

  20. Relationship between osteology and aquatic locomotion in birds: determining modes of locomotion in extinct Ornithurae.

    Science.gov (United States)

    Hinić-Frlog, S; Motani, R

    2010-02-01

    The evolutionary history of aquatic invasion in birds would be incomplete without incorporation of extinct species. We show that aquatic affinities in fossil birds can be inferred by multivariate analysis of skeletal features and locomotion of 245 species of extant birds. Regularized discriminant analyses revealed that measurements of appendicular skeletons successfully separated diving birds from surface swimmers and flyers, while also discriminating among different underwater modes of swimming. The high accuracy of this method allows detection of skeletal characteristics that are indicative of aquatic locomotion and inference of such locomotion in bird species with insufficient behavioural information. Statistical predictions based on the analyses confirm qualitative assessments for both foot-propelled (Hesperornithiformes) and wing-propelled (Copepteryx) underwater locomotion in fossil birds. This is the first quantitative inference of underwater modes of swimming in fossil birds, enabling future studies of locomotion in extinct birds and evolutionary transitions among locomotor modes in avian lineage.

  1. Development of locomotion in a subsocial spider.

    Science.gov (United States)

    Ahn, Soon Kil; Kim, Kil Won

    2015-04-01

    Following consumption of their mother, the subsocial spider Amaurobius ferox remain together, exhibiting distinctive behaviours in response to intruders into the natal nest. We examined the ontogeny and characteristics of locomotory behaviours in A. ferox during this post-maternal social period. Locomotion of the spiderlings, elicited by the introduction of a cricket larva into the natal web, fell into two categories: 'abrupt locomotion' (AL) and 'ordinary locomotion' (OL). AL involved rapid and linear movement, whereas OL involved slower motion, not necessarily in a straight line. Both types of locomotion varied with spiderling age. AL appeared for only a limited period of time whereas the frequency of OL increased linearly over time. AL occurred more collectively than OL: the percentage of participants in a bout of locomotion was 18.67±17.71% vs. 10.22±9.33%. The collective tendency of AL increased up until the seventh day and then decreased, whereas that of OL progressively decreased. The direction of AL responses to the intruder did not vary over time; however, for OL, movements towards increased in frequency over time. Locomotory responses also varied with the intensity of intruder movement. Including transient behaviours, the chronology of different behaviours suggests that behavioural development in A. ferox involves maternal influences and weakens group cohesion and collective tendency. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Passive appendages aid locomotion through symmetry breaking

    Science.gov (United States)

    Bagheri, Shervin; Lacis, Ugis; Mazzino, Andrea; Kellay, Hamid; Brosse, Nicolas; Lundell, Fredrik; Ingremeau, Francois

    2014-11-01

    Plants and animals use plumes, barbs, tails, feathers, hairs, fins, and other types of appendages to aid locomotion. Despite their enormous variation, passive appendages may contribute to locomotion by exploiting the same physical mechanism. We present a new mechanism that applies to body appendages surrounded by a separated flow, which often develops behind moving bodies larger than a few millimeters. We use theory, experiments, and numerical simulations to show that bodies with protrusions turn and drift by exploiting a symmetry-breaking instability similar to the instability of an inverted pendulum. Our model explains why the straight position of an appendage in flowing fluid is unstable and how it stabilizes either to the left or right of the incoming fluid flow direction. The discovery suggests a new mechanism of locomotion that may be relevant for certain organisms; for example, how plumed seeds may drift without wind and how motile animals may passively reorient themselves.

  3. Numerical simulation of human biped locomotion

    International Nuclear Information System (INIS)

    Ishiguro, Misako; Fujisaki, Masahide

    1988-04-01

    This report describes the numerical simulation of the motion of human-like robot which is one of the research theme of human acts simulation program (HASP) begun at the Computing Center of JAERI in 1987. The purpose of the theme is to model the human motion using robotics kinematic/kinetic equations and to get the joint angles as the solution. As the first trial, we treat the biped locomotion (walking) which is the most fundamental human motion. We implemented a computer program on FACOM M-780 computer, where the program is originated from the book of M. Vukobratovic in Yugoslavia, and made a graphic program to draw a walking shot sequence. Mainly described here are the mathematical model of the biped locomotion, implementation method of the computer program, input data for basic walking pattern, computed results and its validation, and graphic representation of human walking image. Literature survey on robotics equation and biped locomotion is also included. (author)

  4. A model for nematode locomotion in soil

    Science.gov (United States)

    Hunt, H. William; Wall, Diana H.; DeCrappeo, Nicole; Brenner, John S.

    2001-01-01

    Locomotion of nematodes in soil is important for both practical and theoretical reasons. We constructed a model for rate of locomotion. The first model component is a simple simulation of nematode movement among finite cells by both random and directed behaviours. Optimisation procedures were used to fit the simulation output to data from published experiments on movement along columns of soil or washed sand, and thus to estimate the values of the model's movement coefficients. The coefficients then provided an objective means to compare rates of locomotion among studies done under different experimental conditions. The second component of the model is an equation to predict the movement coefficients as a function of controlling factors that have been addressed experimentally: soil texture, bulk density, water potential, temperature, trophic group of nematode, presence of an attractant or physical gradient and the duration of the experiment. Parameters of the equation were estimated by optimisation to achieve a good fit to the estimated movement coefficients. Bulk density, which has been reported in a minority of published studies, is predicted to have an important effect on rate of locomotion, at least in fine-textured soils. Soil sieving, which appears to be a universal practice in laboratory studies of nematode movement, is predicted to negatively affect locomotion. Slower movement in finer textured soils would be expected to increase isolation among local populations, and thus to promote species richness. Future additions to the model that might improve its utility include representing heterogeneity within populations in rate of movement, development of gradients of chemical attractants, trade-offs between random and directed components of movement, species differences in optimal temperature and water potential, and interactions among factors controlling locomotion.

  5. Analysis of fuel cell hybrid locomotives

    Science.gov (United States)

    Miller, Arnold R.; Peters, John; Smith, Brian E.; Velev, Omourtag A.

    Led by Vehicle Projects LLC, an international industry-government consortium is developing a 109 t, 1.2 MW road-switcher locomotive for commercial and military railway applications. As part of the feasibility and conceptual-design analysis, a study has been made of the potential benefits of a hybrid power plant in which fuel cells comprise the prime mover and a battery or flywheel provides auxiliary power. The potential benefits of a hybrid power plant are: (i) enhancement of transient power and hence tractive effort; (ii) regenerative braking; (iii) reduction of capital cost. Generally, the tractive effort of a locomotive at low speed is limited by wheel adhesion and not by available power. Enhanced transient power is therefore unlikely to benefit a switcher locomotive, but could assist applications that require high acceleration, e.g. subway trains with all axles powered. In most cases, the value of regeneration in locomotives is minimal. For low-speed applications such as switchers, the available kinetic energy and the effectiveness of traction motors as generators are both minimal. For high-speed heavy applications such as freight, the ability of the auxiliary power device to absorb a significant portion of the available kinetic energy is low. Moreover, the hybrid power plant suffers a double efficiency penalty, namely, losses occur in both absorbing and then releasing energy from the auxiliary device, which result in a net storage efficiency of no more than 50% for present battery technology. Capital cost in some applications may be reduced. Based on an observed locomotive duty cycle, a cost model shows that a hybrid power plant for a switcher may indeed reduce capital cost. Offsetting this potential benefit are the increased complexity, weight and volume of the power plant, as well as 20-40% increased fuel consumption that results from lower efficiency. Based on this analysis, the consortium has decided to develop a pure fuel cell road-switcher locomotive

  6. Switched on!

    CERN Multimedia

    2008-01-01

    Like a star arriving on stage, impatiently followed by each member of CERN personnel and by millions of eyes around the world, the first beam of protons has circulated in the LHC. After years in the making and months of increasing anticipation, today the work of hundreds of people has borne fruit. WELL DONE to all! Successfully steered around the 27 kilometres of the world’s most powerful particle accelerator at 10:28 this morning, this first beam of protons circulating in the ring marks a key moment in the transition from over two decades of preparation to a new era of scientific discovery. "It’s a fantastic moment," said the LHC project leader Lyn Evans, "we can now look forward to a new era of understanding about the origins and evolution of the universe". Starting up a major new particle accelerator takes much more than flipping a switch. Thousands of individual elements have to work in harmony, timings have to be synchronize...

  7. Large and limbless: the locomotion of snakes

    Science.gov (United States)

    Hu, David

    2008-03-01

    In efforts to understand snake locomotion, we consider one of their various gaits. By contracting and extending their bodies unidirectionally like a slinky, large snakes propel themselves in a straight line. In a combined experimental and theoretical investigation, we here report on the dynamics of a boa constrictor alongside the analysis of an n-linked extensible crawler model. Constraints on their locomotion are quantified and discussed, such as the elasticity, frictional anisotropy and abrasive wear of their skin. Also presented are certain snake behaviors that culminate in their tying themselves into knots.

  8. Locomotion of Paramecium in patterned environments

    Science.gov (United States)

    Park, Eun-Jik; Eddins, Aja; Kim, Junil; Yang, Sung; Jana, Saikat; Jung, Sunghwan

    2011-10-01

    Ciliary organisms like Paramecium Multimicronucleatum locomote by synchronized beating of cilia that produce metachronal waves over their body. In their natural environments they navigate through a variety of environments especially surfaces with different topology. We study the effects of wavy surfaces patterned on the PDMS channels on the locomotive abilities of Paramecium by characterizing different quantities like velocity amplitude and wavelength of the trajectories traced. We compare this result with the swimming characteristics in straight channels and draw conclusions about the effects of various patterned surfaces.

  9. DESIGN IMPROVEMENT OF THE LOCOMOTIVE RUNNING GEARS

    Directory of Open Access Journals (Sweden)

    S. V. Myamlin

    2013-09-01

    Full Text Available Purpose. To determine the dynamic qualities of the mainline freight locomotives characterizing the safe motion in tangent and curved track sections at all operational speeds, one needs a whole set of studies, which includes a selection of the design scheme, development of the corresponding mathematical model of the locomotive spatial fluctuations, construction of the computer calculation program, conducting of the theoretical and then experimental studies of the new designs. In this case, one should compare the results with existing designs. One of the necessary conditions for the qualitative improvement of the traction rolling stock is to define the parameters of its running gears. Among the issues related to this problem, an important place is occupied by the task of determining the locomotive dynamic properties on the stage of projection, taking into account the selected technical solutions in the running gear design. Methodology. The mathematical modeling studies are carried out by the numerical integration method of the dynamic loading for the mainline locomotive using the software package «Dynamics of Rail Vehicles » («DYNRAIL». Findings. As a result of research for the improvement of locomotive running gear design it can be seen that the creation of the modern locomotive requires from engineers and scientists the realization of scientific and technical solutions. The solutions enhancing design speed with simultaneous improvement of the traction, braking and dynamic qualities to provide a simple and reliable design, especially the running gear, reducing the costs for maintenance and repair, low initial cost and operating costs for the whole service life, high traction force when starting, which is as close as possible to the ultimate force of adhesion, the ability to work in multiple traction mode and sufficient design speed. Practical Value. The generalization of theoretical, scientific and methodological, experimental studies aimed

  10. Serotonin controls initiation of locomotion and afferent modulation of coordination via 5‐HT7 receptors in adult rats

    Science.gov (United States)

    Majczyński, Henryk; Couto, Erika; Gardiner, Phillip F.; Stecina, Katinka; Sławińska, Urszula

    2016-01-01

    intact rats suppressed locomotion by partial paralysis of hindlimbs. This occurred without a direct effect on motoneurons as revealed by an investigation of reflex activity. The antagonist disrupted intra‐ and interlimb coordination during locomotion in all intact animals but not during fictive locomotion induced by stimulation of the mesencephalic locomotor region (MLR). MLR‐evoked fictive locomotion was transiently blocked, then the amplitude and frequency of rhythmic activity were reduced by SB269970, consistent with the notion that the MLR activates 5‐HT neurons, leading to excitation of central pattern generator neurons with 5‐HT7 receptors. Effects on coordination in adults required the presence of afferent input, suggesting a switch to 5‐HT7 receptor‐mediated control of sensory pathways during development. PMID:27393215

  11. Locomotive Schedule Optimization for Da-qin Heavy Haul Railway

    OpenAIRE

    Su, Ruiye; Zhou, Leishan; Tang, Jinjin

    2015-01-01

    The main difference between locomotive schedule of heavy haul railways and that of regular rail transportation is the number of locomotives utilized for one train. One heavy-loaded train usually has more than one locomotive, but a regular train only has one. This paper develops an optimization model for the multilocomotive scheduling problem (MLSP) through analyzing the current locomotive schedule of Da-qin Railway. The objective function of our paper is to minimize the total number of utiliz...

  12. 49 CFR 230.101 - Steam locomotive driving journal boxes.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Steam locomotive driving journal boxes. 230.101... Locomotives and Tenders Running Gear § 230.101 Steam locomotive driving journal boxes. (a) Driving journal boxes. Driving journal boxes shall be maintained in a safe and suitable condition for service. Not more...

  13. Relation between observed locomotion traits and locomotion score in dairy cows.

    Science.gov (United States)

    Schlageter-Tello, Andrés; Bokkers, Eddie A M; Groot Koerkamp, Peter W G; Van Hertem, Tom; Viazzi, Stefano; Romanini, Carlos E B; Halachmi, Ilan; Bahr, Claudia; Berckmans, Daniël; Lokhorst, Kees

    2015-12-01

    Lameness is still an important problem in modern dairy farming. Human observation of locomotion, by looking at different traits in one go, is used in practice to assess locomotion. The objectives of this article were to determine which individual locomotion traits are most related to locomotion scores in dairy cows, and whether experienced raters are capable of scoring these individual traits consistently. Locomotion and 5 individual locomotion traits (arched back, asymmetric gait, head bobbing, reluctance to bear weight, and tracking up) were scored independently on a 5-level scale for 58 videos of different cows. Videos were shown to 10 experienced raters in 2 different scoring sessions. Relations between locomotion score and traits were estimated by 3 logistic regression models aiming to calculate the size of the fixed effects on the probability of scoring a cow in 1 of the 5 levels of the scale (model 1) and the probability of classifying a cow as lame (locomotion score ≥3; model 2) or as severely lame (locomotion score ≥4; model 3). Fixed effects were rater, session, traits, and interactions among fixed effects. Odds ratios were calculated to estimate the relative probability to classify a cow as lame when an altered (trait score ≥3) or severely altered trait (trait score ≥4) was present. Overall intrarater and interrater reliability and agreement were calculated as weighted kappa coefficient (κw) and percentage of agreement, respectively. Specific intrarater and interrater agreement for individual levels within a 5-level scale were calculated. All traits were significantly related to the locomotion score when scored with a 5-level scale and when classified as (severely) lame or nonlame. Odds ratios for altered and severely altered traits were 10.8 and 14.5 for reluctance to bear weight, 6.5 and 7.2 for asymmetric gait, and 4.8 and 3.2 for arched back, respectively. Raters showed substantial variation in reliability and agreement values when scoring

  14. 49 CFR 210.9 - Movement of a noise defective locomotive, rail car, or consist of a locomotive and rail cars.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Movement of a noise defective locomotive, rail car, or consist of a locomotive and rail cars. 210.9 Section 210.9 Transportation Other Regulations... locomotive, rail car, or consist of a locomotive and rail cars. A locomotive, rail car, or consist of a...

  15. 76 FR 2199 - Locomotive Safety Standards

    Science.gov (United States)

    2011-01-12

    ... existing regulations. The proposal incorporates existing industry and engineering best practices related to... Overview of Proposed Requirements Trends in locomotive operation, concern about the safe design of... used many of the same sub-assemblies of pneumatic valves, electronic controls and software (referred to...

  16. Locomotion of C elegans in structured environments

    Science.gov (United States)

    Majmudar, Trushant; Keaveny, Eric; Shelley, Michael; Zhang, Jun

    2010-11-01

    Undulatory locomotion of microorganisms like soil-dwelling worms and sperm, in structured environments, is ubiquitous in nature. They navigate complex environments consisting of fluids and obstacles, negotiating hydrodynamic effects and geometrical constraints. Here we report experimental observations on the locomotion of C elegans swimming in arrays of micro-pillars in square lattices, with different lattice spacing. We observe that the worm employs a number of different locomotion strategies depending on the lattice spacing. As observed previously in the literature, we uncover regimes of enhanced locomotion, where the velocity is much higher than the free-swimming velocity. In addition, we also observe changes in frequency, velocity, and the gait of the worm as a function of lattice spacing. We also track the worm over time and find that it exhibits super-diffusive behavior and covers a larger area by utilizing the obstacles. These results may have significant impact on the foraging behavior of the worm in its natural environment. Our experimental approach, in conjunction with modeling and simulations, allows us to disentangle the effects of structure and hydrodynamics for an undulating microorganism.

  17. Evidence for Motor Simulation in Imagined Locomotion

    Science.gov (United States)

    Kunz, Benjamin R.; Creem-Regehr, Sarah H.; Thompson, William B.

    2009-01-01

    A series of experiments examined the role of the motor system in imagined movement, finding a strong relationship between imagined walking performance and the biomechanical information available during actual walking. Experiments 1 through 4 established the finding that real and imagined locomotion differ in absolute walking time. We then tested…

  18. Muscle spindle and fusimotor activity in locomotion.

    Science.gov (United States)

    Ellaway, Peter H; Taylor, Anthony; Durbaba, Rade

    2015-08-01

    Mammals may exhibit different forms of locomotion even within a species. A particular form of locomotion (e.g. walk, run, bound) appears to be selected by supraspinal commands, but the precise pattern, i.e. phasing of limbs and muscles, is generated within the spinal cord by so-called central pattern generators. Peripheral sense organs, particularly the muscle spindle, play a crucial role in modulating the central pattern generator output. In turn, the feedback from muscle spindles is itself modulated by static and dynamic fusimotor (gamma) neurons. The activity of muscle spindle afferents and fusimotor neurons during locomotion in the cat is reviewed here. There is evidence for some alpha-gamma co-activation during locomotion involving static gamma motoneurons. However, both static and dynamic gamma motoneurons show patterns of modulation that are distinct from alpha motoneuron activity. It has been proposed that static gamma activity may drive muscle spindle secondary endings to signal the intended movement to the central nervous system. Dynamic gamma motoneuron drive appears to prime muscle spindle primary endings to signal transitions in phase of the locomotor cycle. These findings come largely from reduced animal preparations (decerebrate) and require confirmation in freely moving intact animals. © 2015 Anatomical Society.

  19. Morphological self stabilization of locomotion gaits: illustration on a few examples from bio-inspired locomotion

    OpenAIRE

    Chevallereau , Christine; Boyer , Frédéric; Porez , Mathieu; Mauny , Johan; Aoustin , Yannick

    2017-01-01

    International audience; — To a large extent, robotics locomotion can be viewed as cyclic motions, named gaits. Due to the high complexity of the locomotion dynamics, to find the control laws that ensure an expected gait and its stability with respect to external perturbations, is a challenging issue for feedback control. To address this issue, a promising way is to take inspiration from animals that intensively exploit the interactions of the passive degrees of freedom of their body with thei...

  20. Locomotive Schedule Optimization for Da-qin Heavy Haul Railway

    Directory of Open Access Journals (Sweden)

    Ruiye Su

    2015-01-01

    Full Text Available The main difference between locomotive schedule of heavy haul railways and that of regular rail transportation is the number of locomotives utilized for one train. One heavy-loaded train usually has more than one locomotive, but a regular train only has one. This paper develops an optimization model for the multilocomotive scheduling problem (MLSP through analyzing the current locomotive schedule of Da-qin Railway. The objective function of our paper is to minimize the total number of utilized locomotives. The MLSP is nondeterministic polynomial (NP hard. Therefore, we convert the multilocomotive traction problem into a single-locomotive traction problem. Then, the single-locomotive traction problem (SLTP can be converted into an assignment problem. The Hungarian algorithm is applied to solve the model and obtain the optimal locomotive schedule. We use the variance of detention time of locomotives at stations to evaluate the stability of locomotive schedule. In order to evaluate the effectiveness of the proposed optimization model, case studies for 20 kt and 30 kt heavy-loaded combined trains on Da-qin Railway are both conducted. Compared to the current schedules, the optimal schedules from the proposed models can save 62 and 47 locomotives for 20 kt and 30 kt heavy-loaded combined trains, respectively. Therefore, the effectiveness of the proposed model and its solution algorithm are both valid.

  1. Analysis of emotionality and locomotion in radio-frequency electromagnetic radiation exposed rats.

    Science.gov (United States)

    Narayanan, Sareesh Naduvil; Kumar, Raju Suresh; Paval, Jaijesh; Kedage, Vivekananda; Bhat, M Shankaranarayana; Nayak, Satheesha; Bhat, P Gopalakrishna

    2013-07-01

    In the current study the modulatory role of mobile phone radio-frequency electromagnetic radiation (RF-EMR) on emotionality and locomotion was evaluated in adolescent rats. Male albino Wistar rats (6-8 weeks old) were randomly assigned into the following groups having 12 animals in each group. Group I (Control): they remained in the home cage throughout the experimental period. Group II (Sham exposed): they were exposed to mobile phone in switch-off mode for 28 days, and Group III (RF-EMR exposed): they were exposed to RF-EMR (900 MHz) from an active GSM (Global system for mobile communications) mobile phone with a peak power density of 146.60 μW/cm(2) for 28 days. On 29th day, the animals were tested for emotionality and locomotion. Elevated plus maze (EPM) test revealed that, percentage of entries into the open arm, percentage of time spent on the open arm and distance travelled on the open arm were significantly reduced in the RF-EMR exposed rats. Rearing frequency and grooming frequency were also decreased in the RF-EMR exposed rats. Defecation boli count during the EPM test was more with the RF-EMR group. No statistically significant difference was found in total distance travelled, total arm entries, percentage of closed arm entries and parallelism index in the RF-EMR exposed rats compared to controls. Results indicate that mobile phone radiation could affect the emotionality of rats without affecting the general locomotion.

  2. Development of a Novel Locomotion Algorithm for Snake Robot

    International Nuclear Information System (INIS)

    Khan, Raisuddin; Billah, Md Masum; Watanabe, Mitsuru; Shafie, A A

    2013-01-01

    A novel algorithm for snake robot locomotion is developed and analyzed in this paper. Serpentine is one of the renowned locomotion for snake robot in disaster recovery mission to overcome narrow space navigation. Several locomotion for snake navigation, such as concertina or rectilinear may be suitable for narrow spaces, but is highly inefficient if the same type of locomotion is used even in open spaces resulting friction reduction which make difficulties for snake movement. A novel locomotion algorithm has been proposed based on the modification of the multi-link snake robot, the modifications include alterations to the snake segments as well elements that mimic scales on the underside of the snake body. Snake robot can be able to navigate in the narrow space using this developed locomotion algorithm. The developed algorithm surmount the others locomotion limitation in narrow space navigation

  3. Effects of locomotion extend throughout the mouse early visual system.

    Science.gov (United States)

    Erisken, Sinem; Vaiceliunaite, Agne; Jurjut, Ovidiu; Fiorini, Matilde; Katzner, Steffen; Busse, Laura

    2014-12-15

    Neural responses in visual cortex depend not only on sensory input but also on behavioral context. One such context is locomotion, which modulates single-neuron activity in primary visual cortex (V1). How locomotion affects neuronal populations across cortical layers and in precortical structures is not well understood. We performed extracellular multielectrode recordings in the visual system of mice during locomotion and stationary periods. We found that locomotion influenced activity of V1 neurons with a characteristic laminar profile and shaped the population response by reducing pairwise correlations. Although the reduction of pairwise correlations was restricted to cortex, locomotion slightly but consistently increased firing rates and controlled tuning selectivity already in the dorsolateral geniculate nucleus (dLGN) of the thalamus. At the level of the eye, increases in locomotion speed were associated with pupil dilation. These findings document further, nonmultiplicative effects of locomotion, reaching earlier processing stages than cortex. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. [Job stress in locomotive attendants in a locomotive depot and related influencing factors].

    Science.gov (United States)

    Kang, L; Jia, X C; Lu, F; Zhou, W H; Chen, R

    2017-10-20

    Objective: To investigate the current status of job stress in locomotive attendants in a locomotive depot and related influencing factors. Methods: From 2012 to 2013, cluster sampling was used to select 1500 locomotive attendants in a locomotive depot in Zhengzhou Railway Bureau as respondents.The contents of the investigation included general data and occupational information.A job satisfaction questionnaire was used to investigate the degree of satisfaction, a depression scale was used to investigate the frequency of symptoms, and a daily stress scale was used to investigate the frequency of fatigue and stress. Results: There was a significant difference in depression score between locomotive attendants with different ages, working years, degrees of education, working situations of spouse, total monthly family incomes, numbers of times of attendanceat night, monthly numbers of times of attendance,ormonthly attendance times( P job satisfaction score between locomotive attendants with different ages,working years, degrees of education, working situations of spouse, total monthly family incomes, numbers of times of attendance at night, monthly attendance times,or ways to work( P job satisfaction( β =1.546)and monthly number of times of attendance,working years,attendance time at night,and degree of education were negatively correlated with job satisfaction( β =-0.185,-0.097,-0.020,and -1.106); monthly number of times of attendance andcommute time were positively correlated with depression( β =0.243 and 0.029); attendance time at night,working situation of spouse,commute time,monthly number of times of attendance,degree of education,and working years were positively correlated with daily stress( β =0.006,0.473,0.010,0.043,0.585, and 0.028). Conclusion: Number of times of attendance, attendance time,working years,and spouse are influencing factors for job stress in locomotive attendants. Improvement in work process and care for their personal life help to reduce

  5. Shared strategies for behavioral switching: understanding how locomotor patterns are turned on and off

    Directory of Open Access Journals (Sweden)

    Karen A Mesce

    2010-07-01

    Full Text Available Animals frequently switch from one behavior to another, often to meet the demands of their changing environment or internal state. What factors control these behavioral switches and the selection of what to do or what not to do? To address these issues, we will focus on the locomotor behaviors of two distantly related ‘worms’, the medicinal leech Hirudo verbana (clade Lophotrochozoa and the nematode Caenorhabditis elegans (clade Ecdysozoa. Although the neural architecture and body morphology of these organisms are quite distinct, they appear to switch between different forms of locomotion by using similar strategies of decision-making. For example, information that distinguishes between liquid and more solid environments dictates whether an animal swims or crawls. In the leech, dopamine biases locomotor neural networks so that crawling is turned on and swimming is turned off. In C. elegans, dopamine may also promote crawling, a form of locomotion that has gained new attention.

  6. Locomotion control of hybrid cockroach robots

    Science.gov (United States)

    Sanchez, Carlos J.; Chiu, Chen-Wei; Zhou, Yan; González, Jorge M.; Vinson, S. Bradleigh; Liang, Hong

    2015-01-01

    Natural systems retain significant advantages over engineered systems in many aspects, including size and versatility. In this research, we develop a hybrid robotic system using American (Periplaneta americana) and discoid (Blaberus discoidalis) cockroaches that uses the natural locomotion and robustness of the insect. A tethered control system was firstly characterized using American cockroaches, wherein implanted electrodes were used to apply an electrical stimulus to the prothoracic ganglia. Using this approach, larger discoid cockroaches were engineered into a remotely controlled hybrid robotic system. Locomotion control was achieved through electrical stimulation of the prothoracic ganglia, via a remotely operated backpack system and implanted electrodes. The backpack consisted of a microcontroller with integrated transceiver protocol, and a rechargeable battery. The hybrid discoid roach was able to walk, and turn in response to an electrical stimulus to its nervous system with high repeatability of 60%. PMID:25740855

  7. Using entropy measures to characterize human locomotion.

    Science.gov (United States)

    Leverick, Graham; Szturm, Tony; Wu, Christine Q

    2014-12-01

    Entropy measures have been widely used to quantify the complexity of theoretical and experimental dynamical systems. In this paper, the value of using entropy measures to characterize human locomotion is demonstrated based on their construct validity, predictive validity in a simple model of human walking and convergent validity in an experimental study. Results show that four of the five considered entropy measures increase meaningfully with the increased probability of falling in a simple passive bipedal walker model. The same four entropy measures also experienced statistically significant increases in response to increasing age and gait impairment caused by cognitive interference in an experimental study. Of the considered entropy measures, the proposed quantized dynamical entropy (QDE) and quantization-based approximation of sample entropy (QASE) offered the best combination of sensitivity to changes in gait dynamics and computational efficiency. Based on these results, entropy appears to be a viable candidate for assessing the stability of human locomotion.

  8. Serpentine locomotion through elastic energy release

    OpenAIRE

    Dal Corso, Francesco; Misseroni, Diego; Pugno, Nicola; Movchan, A. B.; Movchan, N. V.; Bigoni, Davide

    2017-01-01

    A model for serpentine locomotion is derived from a novel perspective based on concepts from configurational mechanics. The motion is realized through the release of the elastic energy of a deformable rod, sliding inside a frictionless channel, which represents a snake moving against lateral restraints. A new formulation is presented, correcting previous results and including situations never analysed so far, as in the cases when the serpent's body lies only partially inside the restraining c...

  9. Exotendons for assistance of human locomotion

    Directory of Open Access Journals (Sweden)

    van den Bogert Antonie J

    2003-10-01

    Full Text Available Abstract Background Powered robotic exoskeletons for assistance of human locomotion are currently under development for military and medical applications. The energy requirements for such devices are excessive, and this has become a major obstacle for practical applications. Legged locomotion in many animals, however, is very energy efficient. We propose that poly-articular elastic mechanisms are a major contributor to the economy of locomotion in such specialized animals. Consequently, it should be possible to design unpowered assistive devices that make effective use of similar mechanisms. Methods A passive assistive technology is presented, based on long elastic cords attached to an exoskeleton and guided by pulleys placed at the joints. A general optimization procedure is described for finding the best geometrical arrangement of such "exotendons" for assisting a specific movement. Optimality is defined either as minimal residual joint moment or as minimal residual joint power. Four specific exotendon systems with increasing complexity are considered. Representative human gait data were used to optimize each of these four systems to achieve maximal assistance for normal walking. Results The most complex exotendon system, with twelve pulleys per limb, was able to reduce the joint moments required for normal walking by 71% and joint power by 74%. A simpler system, with only three pulleys per limb, could reduce joint moments by 46% and joint power by 47%. Conclusion It is concluded that unpowered passive elastic devices can substantially reduce the muscle forces and the metabolic energy needed for walking, without requiring a change in movement. When optimally designed, such devices may allow independent locomotion in patients with large deficits in muscle function.

  10. On the rules for aquatic locomotion

    Science.gov (United States)

    Saadat, M.; Fish, F. E.; Domel, A. G.; Di Santo, V.; Lauder, G. V.; Haj-Hariri, H.

    2017-08-01

    We present unifying rules governing the efficient locomotion of swimming fish and marine mammals. Using scaling and dimensional analysis, supported by new experimental data, we show that efficient locomotion occurs when the values of the Strouhal (St) number St (=f A /U ) and A*(=A /L ) , two nondimensional numbers that relate forward speed U , tail-beat amplitude A , tail-beat frequency f , and the length of the swimmer L are bound to the tight ranges of 0.2-0.4 and 0.1-0.3, respectively. The tight range of 0.2-0.4 for the St number has previously been associated with optimal thrust generation. We show that the St number alone is insufficient to achieve optimal aquatic locomotion, and an additional condition on A* is needed. More importantly, we show that when swimming at minimal power consumption, the Strouhal number of a cruising swimmer is predetermined solely by the shape and drag characteristics of the swimmer. We show that diverse species of fish and cetaceans cruise indeed with the St number and A* predicted by our theory. Our findings provide a physical explanation as to why fast aquatic swimmers cruise with a relatively constant tail-beat amplitude of approximately 20% of the body length, and their swimming speed is nearly proportional to their tail-beat frequency.

  11. Controller Architectures for Switching

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Poulsen, Niels Kjølstad

    2009-01-01

    This paper investigate different controller architectures in connection with controller switching. The controller switching is derived by using the Youla-Jabr-Bongiorno-Kucera (YJBK) parameterization. A number of different architectures for the implementation of the YJBK parameterization...... are described and applied in connection with controller switching. An architecture that does not include inversion of the coprime factors is introduced. This architecture will make controller switching particular simple....

  12. Neurobiology of Caenorhabditis elegans Locomotion: Where Do We Stand?

    Science.gov (United States)

    Gjorgjieva, Julijana; Biron, David; Haspel, Gal

    2014-01-01

    Animals use a nervous system for locomotion in some stage of their life cycle. The nematode Caenorhabditis elegans, a major animal model for almost all fields of experimental biology, has long been used for detailed studies of genetic and physiological locomotion mechanisms. Of its 959 somatic cells, 302 are neurons that are identifiable by lineage, location, morphology, and neurochemistry in every adult hermaphrodite. Of those, 75 motoneurons innervate body wall muscles that provide the thrust during locomotion. In this Overview, we concentrate on the generation of either forward- or backward-directed motion during crawling and swimming. We describe locomotion behavior, the parts constituting the locomotion system, and the relevant neuronal connectivity. Because it is not yet fully understood how these components combine to generate locomotion, we discuss competing hypotheses and models. PMID:26955070

  13. Serotonin Influences Locomotion in the Nudibranch Mollusc Melibe leonina

    OpenAIRE

    LEWIS, STEFANIE L.; LYONS, DEBORAH E.; MEEKINS, TIFFANIE L.; NEWCOMB, JAMES M.

    2011-01-01

    Serotonin (5-HT) influences locomotion in many animals, from flatworms to mammals. This study examined the effects of 5-HT on locomotion in the nudibranch mollusc Melibe leonina (Gould, 1852). M. leonina exhibits two modes of locomotion, crawling and swimming. Animals were bath-immersed in a range of concentrations of 5-HT or injected with various 5-HT solutions into the hemolymph and then monitored for locomotor activity. In contrast to other gastropods studied, M. leonina showed no signific...

  14. A contribution about ferrofluid based flow manipulation and locomotion systems

    International Nuclear Information System (INIS)

    Zimmermann, K; Zeidis, I; Bohm, V; Popp, J

    2009-01-01

    With the background of developing apedal bionic inspired locomotion systems for future application fields like autonomous (swarm) robots, medical engineering and inspection systems, this article presents a selection of locomotion systems with bifluidic flow control using ferrofluid. By controlling the change of shape, position and pressure of the ferrofluid in a secondary low viscous fluid by magnetic fields locomotion of objects or the ferrofluid itself can be realised. The locomotion of an object is caused in the first example by a ferrofluid generated flow of the secondary fluid and in the second and third case by the direct alteration of the ferrofluid position.

  15. A contribution about ferrofluid based flow manipulation and locomotion systems

    Energy Technology Data Exchange (ETDEWEB)

    Zimmermann, K; Zeidis, I; Bohm, V; Popp, J [TU Ilmenau, Fak. f. Maschinenbau, FG Technische Mechanik, Max-Planck-Ring 12, 98693 Ilmenau (Germany)], E-mail: klaus.zimmermann@tu-ilmenau.de, E-mail: jana.popp@tu-ilmenau.de

    2009-02-01

    With the background of developing apedal bionic inspired locomotion systems for future application fields like autonomous (swarm) robots, medical engineering and inspection systems, this article presents a selection of locomotion systems with bifluidic flow control using ferrofluid. By controlling the change of shape, position and pressure of the ferrofluid in a secondary low viscous fluid by magnetic fields locomotion of objects or the ferrofluid itself can be realised. The locomotion of an object is caused in the first example by a ferrofluid generated flow of the secondary fluid and in the second and third case by the direct alteration of the ferrofluid position.

  16. LFP Oscillations in the Mesencephalic Locomotor Region during Voluntary Locomotion

    Directory of Open Access Journals (Sweden)

    Brian R. Noga

    2017-05-01

    Full Text Available Oscillatory rhythms in local field potentials (LFPs are thought to coherently bind cooperating neuronal ensembles to produce behaviors, including locomotion. LFPs recorded from sites that trigger locomotion have been used as a basis for identification of appropriate targets for deep brain stimulation (DBS to enhance locomotor recovery in patients with gait disorders. Theta band activity (6–12 Hz is associated with locomotor activity in locomotion-inducing sites in the hypothalamus and in the hippocampus, but the LFPs that occur in the functionally defined mesencephalic locomotor region (MLR during locomotion have not been determined. Here we record the oscillatory activity during treadmill locomotion in MLR sites effective for inducing locomotion with electrical stimulation in rats. The results show the presence of oscillatory theta rhythms in the LFPs recorded from the most effective MLR stimulus sites (at threshold ≤60 μA. Theta activity increased at the onset of locomotion, and its power was correlated with the speed of locomotion. In animals with higher thresholds (>60 μA, the correlation between locomotor speed and theta LFP oscillations was less robust. Changes in the gamma band (previously recorded in vitro in the pedunculopontine nucleus (PPN, thought to be a part of the MLR were relatively small. Controlled locomotion was best achieved at 10–20 Hz frequencies of MLR stimulation. Our results indicate that theta and not delta or gamma band oscillation is a suitable biomarker for identifying the functional MLR sites.

  17. The need for speed in rodent locomotion analyses.

    Science.gov (United States)

    Batka, Richard J; Brown, Todd J; Mcmillan, Kathryn P; Meadows, Rena M; Jones, Kathryn J; Haulcomb, Melissa M

    2014-10-01

    Locomotion analysis is now widely used across many animal species to understand the motor defects in disease, functional recovery following neural injury, and the effectiveness of various treatments. More recently, rodent locomotion analysis has become an increasingly popular method in a diverse range of research. Speed is an inseparable aspect of locomotion that is still not fully understood, and its effects are often not properly incorporated while analyzing data. In this hybrid manuscript, we accomplish three things: (1) review the interaction between speed and locomotion variables in rodent studies, (2) comprehensively analyze the relationship between speed and 162 locomotion variables in a group of 16 wild-type mice using the CatWalk gait analysis system, and (3) develop and test a statistical method in which locomotion variables are analyzed and reported in the context of speed. Notable results include the following: (1) over 90% of variables, reported by CatWalk, were dependent on speed with an average R(2) value of 0.624, (2) most variables were related to speed in a nonlinear manner, (3) current methods of controlling for speed are insufficient, and (4) the linear mixed model is an appropriate and effective statistical method for locomotion analyses that is inclusive of speed-dependent relationships. Given the pervasive dependency of locomotion variables on speed, we maintain that valid conclusions from locomotion analyses cannot be made unless they are analyzed and reported within the context of speed. © 2014 Wiley Periodicals, Inc.

  18. LFP Oscillations in the Mesencephalic Locomotor Region during Voluntary Locomotion.

    Science.gov (United States)

    Noga, Brian R; Sanchez, Francisco J; Villamil, Luz M; O'Toole, Christopher; Kasicki, Stefan; Olszewski, Maciej; Cabaj, Anna M; Majczyński, Henryk; Sławińska, Urszula; Jordan, Larry M

    2017-01-01

    Oscillatory rhythms in local field potentials (LFPs) are thought to coherently bind cooperating neuronal ensembles to produce behaviors, including locomotion. LFPs recorded from sites that trigger locomotion have been used as a basis for identification of appropriate targets for deep brain stimulation (DBS) to enhance locomotor recovery in patients with gait disorders. Theta band activity (6-12 Hz) is associated with locomotor activity in locomotion-inducing sites in the hypothalamus and in the hippocampus, but the LFPs that occur in the functionally defined mesencephalic locomotor region (MLR) during locomotion have not been determined. Here we record the oscillatory activity during treadmill locomotion in MLR sites effective for inducing locomotion with electrical stimulation in rats. The results show the presence of oscillatory theta rhythms in the LFPs recorded from the most effective MLR stimulus sites (at threshold ≤60 μA). Theta activity increased at the onset of locomotion, and its power was correlated with the speed of locomotion. In animals with higher thresholds (>60 μA), the correlation between locomotor speed and theta LFP oscillations was less robust. Changes in the gamma band (previously recorded in vitro in the pedunculopontine nucleus (PPN), thought to be a part of the MLR) were relatively small. Controlled locomotion was best achieved at 10-20 Hz frequencies of MLR stimulation. Our results indicate that theta and not delta or gamma band oscillation is a suitable biomarker for identifying the functional MLR sites.

  19. Switching Adaptability in Human-Inspired Sidesteps: A Minimal Model

    Directory of Open Access Journals (Sweden)

    Keisuke Fujii

    2017-06-01

    Full Text Available Humans can adapt to abruptly changing situations by coordinating redundant components, even in bipedality. Conventional adaptability has been reproduced by various computational approaches, such as optimal control, neural oscillator, and reinforcement learning; however, the adaptability in bipedal locomotion necessary for biological and social activities, such as unpredicted direction change in chase-and-escape, is unknown due to the dynamically unstable multi-link closed-loop system. Here we propose a switching adaptation model for performing bipedal locomotion by improving autonomous distributed control, where autonomous actuators interact without central control and switch the roles for propulsion, balancing, and leg swing. Our switching mobility model achieved direction change at any time using only three actuators, although it showed higher motor costs than comparable models without direction change. Our method of evaluating such adaptation at any time should be utilized as a prerequisite for understanding universal motor control. The proposed algorithm may simply explain and predict the adaptation mechanism in human bipedality to coordinate the actuator functions within and between limbs.

  20. Morphological self stabilization of locomotion gaits: illustration on a few examples from bio-inspired locomotion.

    Science.gov (United States)

    Chevallereau, Christine; Boyer, Frédéric; Porez, Mathieu; Mauny, Johan; Aoustin, Yannick

    2017-06-20

    To a large extent, robotics locomotion can be viewed as cyclic motions, named gaits. Due to the high complexity of the locomotion dynamics, to find the control laws that ensure an expected gait and its stability with respect to external perturbations, is a challenging issue for feedback control. To address this issue, a promising way is to take inspiration from animals that intensively exploit the interactions of the passive degrees of freedom of their body with their physical surroundings, to outsource the high-level exteroceptive feedback control to low-level proprioceptive ones. In this case, passive interactions can ensure most of the expected control goals. In this article, we propose a methodological framework to study the role of morphology in the design of locomotion gaits and their stability. This framework ranges from modelling to control aspects, and is illustrated through three examples from bio-inspired locomotion: a three-dimensional micro air vehicle in hovering flight, a pendular planar climber and a bipedal planar walker. In these three cases, we will see how simple considerations based on the morphology of the body can ensure the existence of passive stable gaits without requiring any high-level control.

  1. Guiding locomotion in complex dynamic environments

    Directory of Open Access Journals (Sweden)

    Brett R Fajen

    2013-07-01

    Full Text Available Locomotion in complex dynamic environments is an integral part of many daily activities, including walking in crowded spaces, driving on busy roadways, and playing sports. Many of the tasks that humans perform in such environments involve interactions with moving objects -- that is, they require people to coordinate their own movement with the movements of other objects. A widely adopted framework for research on the detection, avoidance, and interception of moving objects is the bearing angle model, according to which observers move so as to keep the bearing angle of the object constant for interception and varying for obstacle avoidance. The bearing angle model offers a simple, parsimonious account of visual control but has several significant limitations and does not easily scale up to more complex tasks. In this paper, I introduce an alternative account of how humans choose actions and guide locomotion in the presence of moving objects. I show how the new approach addresses the limitations of the bearing angle model and accounts for a variety of behaviors involving moving objects, including (1 choosing whether to pass in front of or behind a moving obstacle, (2 perceiving whether a gap between a pair of moving obstacles is passable, (3 avoiding a collision while passing through single or multiple lanes of traffic, (4 coordinating speed and direction of locomotion during interception, (5 simultaneously intercepting a moving target while avoiding a stationary or moving obstacle, and (6 knowing whether to abandon the chase of a moving target. I also summarize data from recent studies that support the new approach.

  2. Mechanical aspects of legged locomotion control.

    Science.gov (United States)

    Koditschek, Daniel E; Full, Robert J; Buehler, Martin

    2004-07-01

    We review the mechanical components of an approach to motion science that enlists recent progress in neurophysiology, biomechanics, control systems engineering, and non-linear dynamical systems to explore the integration of muscular, skeletal, and neural mechanics that creates effective locomotor behavior. We use rapid arthropod terrestrial locomotion as the model system because of the wealth of experimental data available. With this foundation, we list a set of hypotheses for the control of movement, outline their mathematical underpinning and show how they have inspired the design of the hexapedal robot, RHex.

  3. Serpentine Locomotion Articulated Chain: ANA II

    Directory of Open Access Journals (Sweden)

    A. M. Cardona

    2005-01-01

    Full Text Available When humanity faces challenges in solving problems beyond their technical resources, and has no foundation to solve a problem, engineering must search for an answer developing new concepts and innovative frameworks to excel these limitations and travel beyond our capabilities. This project “Serpentine locomotion articulated chain: ANA II” is a self-contained robot built to evaluate the behavior of the platform being capable of serpentine movements, in a modular chain mechanical design, based on a master/slave architecture.

  4. Viscous streaming for locomotion and transport

    Science.gov (United States)

    Gazzola, Mattia; Parthasarathy, Tejaswin

    2017-11-01

    Rectified and oscillatory flows associated with vibrating boundaries have been employed in a variety of tasks, especially in microfluidics. The associated fluid mechanics is well known in the case of simple geometries, cylinders in particular, yet little is known in the case of active, complex systems. Motivated by potential applications in swimming mini-bots, we established an accurate and robust computational framework to investigate the flow behavior associated with oscillations of multiple and deforming shapes with an emphasis on streaming assisted locomotion and transport systems.

  5. Intraspecific variation in aerobic and anaerobic locomotion

    DEFF Research Database (Denmark)

    Svendsen, Jon Christian; Tirsgård, Bjørn; Cordero, Gerardo A.

    2015-01-01

    Intraspecific variation and trade-off in aerobic and anaerobic traits remain poorly understood in aquatic locomotion. Using gilthead sea bream (Sparus aurata) and Trinidadian guppy (Poecilia reticulata), both axial swimmers, this study tested four hypotheses: (1) gait transition from steady...... to unsteady (i.e., burst-assisted) swimming is associated with anaerobic metabolism evidenced as excess post exercise oxygen consumption (EPOC); (2) variation in swimming performance (critical swimming speed; U crit) correlates with metabolic scope (MS) or anaerobic capacity (i.e., maximum EPOC); (3...

  6. Saturated Switching Systems

    CERN Document Server

    Benzaouia, Abdellah

    2012-01-01

    Saturated Switching Systems treats the problem of actuator saturation, inherent in all dynamical systems by using two approaches: positive invariance in which the controller is designed to work within a region of non-saturating linear behaviour; and saturation technique which allows saturation but guarantees asymptotic stability. The results obtained are extended from the linear systems in which they were first developed to switching systems with uncertainties, 2D switching systems, switching systems with Markovian jumping and switching systems of the Takagi-Sugeno type. The text represents a thoroughly referenced distillation of results obtained in this field during the last decade. The selected tool for analysis and design of stabilizing controllers is based on multiple Lyapunov functions and linear matrix inequalities. All the results are illustrated with numerical examples and figures many of them being modelled using MATLAB®. Saturated Switching Systems will be of interest to academic researchers in con...

  7. Combining Bio-inspired Sensing with Bio-inspired Locomotion

    DEFF Research Database (Denmark)

    Shaikh, Danish; Hallam, John; Christensen-Dalsgaard, Jakob

    In this paper we present a preliminary Braitenberg vehicle–like approach to combine bio-inspired audition with bio-inspired quadruped locomotion in simulation. Locomotion gaits of the salamander–like robot Salamandra robotica are modified by a lizard’s peripheral auditory system model...

  8. The Determination of the Asynchronous Traction Motor Characteristics of Locomotive

    Directory of Open Access Journals (Sweden)

    Pavel Grigorievich Kolpakhchyan

    2017-01-01

    Full Text Available The article deals with the problem of the locomotive asynchronous traction motor control with the AC diesel-electric transmission. The limitations of the torque of the traction motor when powered by the inverter are determined. The recommendations to improve the use of asynchronous traction motor of locomotives with the AC diesel-electric transmission are given.

  9. 49 CFR 232.105 - General requirements for locomotives.

    Science.gov (United States)

    2010-10-01

    ... locomotives. (a) The air brake equipment on a locomotive shall be in safe and suitable condition for service... set pressure at any service application with the brakes control valve in the freight position. If such... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRAKE SYSTEM SAFETY STANDARDS FOR FREIGHT AND OTHER NON-PASSENGER...

  10. Locomotive emissions measurements for various blends of biodiesel fuel.

    Science.gov (United States)

    2014-12-01

    The objective of this project was to assess the effects of various blends of biodiesel on locomotive engine exhaust emissions. The : emission tests were conducted on two locomotive models, a Tier 2 EMD SD70ACe and a Tier 1 Plus GE Dash9-44CW, using t...

  11. THE DYNAMICS AND TRACTION ENERGY METRICS LOCOMOTIVE VL40

    Directory of Open Access Journals (Sweden)

    S. V. Pylypenko

    2008-03-01

    Full Text Available In the article the results of dynamic running and traction-energy tests of the electric locomotive VL40U are presented. In accordance with the test results a conclusion about the suitability of electric locomotive of such a type for operation with trains containing up to 15 passenger coaches inclusive is made.

  12. Architectures of soft robotic locomotion enabled by simple mechanical principles.

    Science.gov (United States)

    Zhu, Liangliang; Cao, Yunteng; Liu, Yilun; Yang, Zhe; Chen, Xi

    2017-06-28

    In nature, a variety of limbless locomotion patterns flourish, from the small or basic life forms (Escherichia coli, amoebae, etc.) to the large or intelligent creatures (e.g., slugs, starfishes, earthworms, octopuses, jellyfishes, and snakes). Many bioinspired soft robots based on locomotion have been developed in the past few decades. In this work, based on the kinematics and dynamics of two representative locomotion modes (i.e., worm-like crawling and snake-like slithering), we propose a broad set of innovative designs for soft mobile robots through simple mechanical principles. Inspired by and going beyond the existing biological systems, these designs include 1-D (dimensional), 2-D, and 3-D robotic locomotion patterns enabled by the simple actuation of continuous beams. We report herein over 20 locomotion modes achieving various locomotion functions, including crawling, rising, running, creeping, squirming, slithering, swimming, jumping, turning, turning over, helix rolling, wheeling, etc. Some are able to reach high speed, high efficiency, and overcome obstacles. All these locomotion strategies and functions can be integrated into a simple beam model. The proposed simple and robust models are adaptive for severe and complex environments. These elegant designs for diverse robotic locomotion patterns are expected to underpin future deployments of soft robots and to inspire a series of advanced designs.

  13. Locomotion With Loads: Practical Techniques for Predicting Performance Outcomes

    Science.gov (United States)

    2015-05-01

    COVERED 15Apr2014 - 14Apr2015 4. TITLE AND SUBTITLE Locomotion With Loads: Practical Techniques for Predicting Performance Outcomes 5a. CONTRACT...al., 1982; Kram & Taylor, 1990) that the mass- specific metabolic cost of locomotion varies in a systematic manner with the linear dimensions of the

  14. Locomotion Induced by Spatial Restriction in Adult Drosophila.

    Science.gov (United States)

    Xiao, Chengfeng; Robertson, R Meldrum

    2015-01-01

    Drosophila adults display an unwillingness to enter confined spaces but the behaviors induced by spatial restriction in Drosophila are largely unknown. We developed a protocol for high-throughput analysis of locomotion and characterized features of locomotion in a restricted space. We observed intense and persistent locomotion of flies in small circular arenas (diameter 1.27 cm), whereas locomotion was greatly reduced in large circular arenas (diameter 3.81 cm). The increased locomotion induced by spatial restriction was seen in male flies but not female flies, indicating sexual dimorphism of the response to spatial restriction. In large arenas, male flies increased locomotion in arenas previously occupied by male but not female individuals. In small arenas, such pre-conditioning had no effect on male flies, which showed intense and persistent locomotion similar to that seen in fresh arenas. During locomotion with spatial restriction, wildtype Canton-S males traveled slower and with less variation in speed than the mutant w1118 carrying a null allele of white gene. In addition, wildtype flies showed a stronger preference for the boundary than the mutant in small arenas. Genetic analysis with a series of crosses revealed that the white gene was not associated with the phenotype of boundary preference in wildtype flies.

  15. Coordination of locomotion with voluntary movements in humans

    NARCIS (Netherlands)

    Ivanenko, Yuri P; Cappellini, Germana; Dominici, Nadia; Poppele, Richard E; Lacquaniti, Francesco

    2005-01-01

    Muscle activity occurring during human locomotion can be accounted for by five basic temporal activation patterns in a variety of locomotion conditions. Here, we examined how these activation patterns interact with muscle activity required for a voluntary movement. Subjects produced a voluntary

  16. Effective switching frequency multiplier inverter

    Science.gov (United States)

    Su, Gui-Jia; Peng, Fang Z.

    2007-08-07

    A switching frequency multiplier inverter for low inductance machines that uses parallel connection of switches and each switch is independently controlled according to a pulse width modulation scheme. The effective switching frequency is multiplied by the number of switches connected in parallel while each individual switch operates within its limit of switching frequency. This technique can also be used for other power converters such as DC/DC, AC/DC converters.

  17. Ciliary Locomotion in Varying Viscosity Flow

    Science.gov (United States)

    Eastham, Patrick; Shoele, Kourosh

    2017-11-01

    Ciliary locomotion is a common method of transportation employed by bacteria. They must be able to move through their environment at will to seek nutrients as well as avoid dangers. While research into bacteria motility has received considerable attention, very little has been done to consider the effects of a spatially-varying viscosity environment on swimming. This presentation will discuss recent research into how bacteria can take advantage of nutrient-dependent viscosity to generate an asymmetric stress field around their body, potentially increasing free-swimming velocity. First, we analytically show that asymptotically small variations in viscosity due to nutrient concentrations can affect the free-swimming velocity of a bacteria. Then we extend our study to fully nonlinear coupling between nutrient concentration and viscosity and employ the Finite Element method to solve a system containing a convection-diffusion equation for nutrient concentration as well as Stokes flow for stress distribution on the swimmer. We will discuss how the free-swimming velocity profile changes for various nutrient Pecletnumbers and ciliary locomotion modes.

  18. Environmental engineering simplifies subterranean locomotion control

    Science.gov (United States)

    Gravish, Nick; Monaenkova, Darya; Goodisman, Michael A. D.; Goldman, Daniel I.

    2013-03-01

    We hypothesize that ants engineer habitats which reduce locomotion control requirements. We studied tunnel construction, and locomotion, in fire ants (Solenopsis invicta, body length L = 0 . 35 +/- 0 . 05). In their daily life, ants forage for food above ground and return resources to the nest. This steady-state tunnel traffic enables high-throughput biomechanics studies of tunnel climbing. In a laboratory experiment we challenged fire ants to climb through 8 cm long glass tunnels (D = 0.1 - 0.9 cm) that separated a nest from an open arena with food and water. During ascending and descending climbs we induced falls by a motion-activated rapid, short, downward translation of the tunnels. Normalized tunnel diameter (D / L) determined the ability of ants to rapidly recover from perturbations. Fall arrest probability was unity for small D / L , and zero for large D / L . The transition from successful to unsuccessful arrest occurred at D / L = 1 . 4 +/- 0 . 3 . Through X-Ray computed tomography study we show that the diameter of ant-excavated tunnels is independent of soil-moisture content (studied from 1-20%) and particle size (50-595 μm diameter), and has a mean value of D / L = 1 . 06 +/- 0 . 23 . Thus fire ants construct tunnels of diameter near the onset of fall instability.

  19. Proprioceptive Actuation Design for Dynamic Legged locomotion

    Science.gov (United States)

    Kim, Sangbae; Wensing, Patrick; Biomimetic Robotics Lab Team

    Designing an actuator system for highly-dynamic legged locomotion exhibited by animals has been one of the grand challenges in robotics research. Conventional actuators designed for manufacturing applications have difficulty satisfying challenging requirements for high-speed locomotion, such as the need for high torque density and the ability to manage dynamic physical interactions. It is critical to introduce a new actuator design paradigm and provide guidelines for its incorporation in future mobile robots for research and industry. To this end, we suggest a paradigm called proprioceptive actuation, which enables highly- dynamic operation in legged machines. Proprioceptive actuation uses collocated force control at the joints to effectively control contact interactions at the feet under dynamic conditions. In the realm of legged machines, this paradigm provides a unique combination of high torque density, high-bandwidth force control, and the ability to mitigate impacts through backdrivability. Results show that the proposed design provides an impact mitigation factor that is comparable to other quadruped designs with series springs to handle impact. The paradigm is shown to enable the MIT Cheetah to manage the application of contact forces during dynamic bounding, with results given down to contact times of 85ms and peak forces over 450N. As a result, the MIT Cheetah achieves high-speed 3D running up to 13mph and jumping over an 18-inch high obstacle. The project is sponsored by DARPA M3 program.

  20. Reversibility in locomotion in granular media

    Science.gov (United States)

    Savoie, William; Goldman, Daniel

    2013-11-01

    A recent study of a self-deforming robot [Hatton et al., PRL, 2013] demonstrated that slow movement in dry granular media resembles locomotion in low Re fluids, in part because inertia is dominated by friction. The study indicated that granular swimming was kinematically reversible, a surprise because yielding in granular flow is irreversible. To investigate if reciprocal motions lead to net displacements in granular swimmers, in laboratory experiments, we study the locomotion of a robotic ``scallop'' consisting of a square body with two flipper-like limbs controlled to flap forward and backward symmetrically (a flap cycle). The body is constrained by linear bearings to allow motion in only one dimension. We vary the the flapping frequency f, the body/flipper burial depth d, and the number of flaps N in a deep bed of 6 mm diameter plastic spheres. Over a range of f and d, the N = 1 cycle produces net translation of the body; however for large N, a cycle produces no net translation. We conclude that symmetric strokes in granular swimming are irreversible at the onset of self-deformation, but become asymptotically reversible. work supported by NSF and ARL.

  1. FreeSWITCH Cookbook

    CERN Document Server

    Minessale, Anthony

    2012-01-01

    This is a problem-solution approach to take your FreeSWITCH skills to the next level, where everything is explained in a practical way. If you are a system administrator, hobbyist, or someone who uses FreeSWITCH on a regular basis, this book is for you. Whether you are a FreeSWITCH expert or just getting started, this book will take your skills to the next level.

  2. Reduction and identification for hybrid dynamical models of terrestrial locomotion

    Science.gov (United States)

    Burden, Samuel A.; Sastry, S. Shankar

    2013-06-01

    The study of terrestrial locomotion has compelling applications ranging from design of legged robots to development of novel prosthetic devices. From a first-principles perspective, the dynamics of legged locomotion seem overwhelmingly complex as nonlinear rigid body dynamics couple to a granular substrate through viscoelastic limbs. However, a surfeit of empirical data demonstrates that animals use a small fraction of their available degrees-of-freedom during locomotion on regular terrain, suggesting that a reduced-order model can accurately describe the dynamical variation observed during steady-state locomotion. Exploiting this emergent phenomena has the potential to dramatically simplify design and control of micro-scale legged robots. We propose a paradigm for studying dynamic terrestrial locomotion using empirically-validated reduced{order models.

  3. Different forms of locomotion in the spinal lamprey.

    Science.gov (United States)

    Hsu, Li-Ju; Orlovsky, Grigori N; Zelenin, Pavel V

    2014-06-01

    Forward locomotion has been extensively studied in different vertebrate animals, and the principal role of spinal mechanisms in the generation of this form of locomotion has been demonstrated. Vertebrate animals, however, are capable of other forms of locomotion, such as backward walking and swimming, sideward walking, and crawling. Do the spinal mechanisms play a principal role in the generation of these forms of locomotion? We addressed this question in lampreys, which are capable of five different forms of locomotion - fast forward swimming, slow forward swimming, backward swimming, forward crawling, and backward crawling. To induce locomotion in lampreys spinalised at the second gill level, we used either electrical stimulation of the spinal cord at different rostrocaudal levels, or tactile stimulation of specific cutaneous receptive fields from which a given form of locomotion could be evoked in intact lampreys. We found that any of the five forms of locomotion could be evoked in the spinal lamprey by electrical stimulation of the spinal cord, and some of them by tactile stimulation. These results suggest that spinal mechanisms in the lamprey, in the absence of phasic supraspinal commands, are capable of generating the basic pattern for all five forms of locomotion observed in intact lampreys. In spinal lampreys, the direction of swimming did not depend on the site of spinal cord stimulation, but on the stimulation strength. The direction of crawling strongly depended on the body configuration. The spinal structures presumably activated by spinal cord stimulation and causing different forms of locomotion are discussed. © 2014 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  4. 40 CFR 1033.515 - Discrete-mode steady-state emission tests of locomotives and locomotive engines.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Discrete-mode steady-state emission... Procedures § 1033.515 Discrete-mode steady-state emission tests of locomotives and locomotive engines. This... a warm-up followed by a sequence of nominally steady-state discrete test modes, as described in...

  5. Plasma erosion switch

    International Nuclear Information System (INIS)

    Mendel, C.W. Jr.; Goldstein, S.A.; Miller, P.A.

    1976-01-01

    The plasma erosion switch is a device capable of initially carrying high currents, and then of opening in nanoseconds to stand off high voltages. It depends upon the erosion of a plasma which initially fills the switch. The sheath between the plasma and the cathode behaves as a diode with a rapidly increasing A-K gap. Preliminary tests of the switch on the Proto I accelerator at Sandia will be described. In these tests, the switch consisted of a cylinder of highly ionized plasma four inches in diameter and one-inch thick surrounding a one-inch cathode. The switch shorted out prepulse voltages and allowed energy to be stored in the diode inductance outside the switch until the accelerator current reached 75 kA. The switch impedance then rose rapidly to approximately 100 ω in 5 nanoseconds, whereupon the accelerator current transferred to the cathode. Current rise rates of 3.10 13 A/sec were limited by cathode turn-on. Voltage rise rates of 10 15 V/sec were achieved. The elimination of prepulse and machine turn-on transients allowed A-K gaps of 2 mm to be used with 2.5 MV pulses, yielding average E fields of 12 MV/cm. Staged versions of the device are being built and should improve rise rates. The switch shows promise for use with future, higher power, lower inductance machines

  6. Switched reluctance motor drives

    Indian Academy of Sciences (India)

    Davis RM, Ray WF, Blake RJ 1981 Inverter drive for switched reluctance: circuits and component ratings. Inst. Elec. Eng. Proc. B128: 126-136. Ehsani M. 1991 Position Sensor elimination technique for the switched reluctance motor drive. US Patent No. 5,072,166. Ehsani M, Ramani K R 1993 Direct control strategies based ...

  7. Switch on, switch off: stiction in nanoelectromechanical switches

    KAUST Repository

    Wagner, Till J W

    2013-06-13

    We present a theoretical investigation of stiction in nanoscale electromechanical contact switches. We develop a mathematical model to describe the deflection of a cantilever beam in response to both electrostatic and van der Waals forces. Particular focus is given to the question of whether adhesive van der Waals forces cause the cantilever to remain in the \\'ON\\' state even when the electrostatic forces are removed. In contrast to previous studies, our theory accounts for deflections with large slopes (i.e. geometrically nonlinear). We solve the resulting equations numerically to study how a cantilever beam adheres to a rigid electrode: transitions between \\'free\\', \\'pinned\\' and \\'clamped\\' states are shown to be discontinuous and to exhibit significant hysteresis. Our findings are compared to previous results from linearized models and the implications for nanoelectromechanical cantilever switch design are discussed. © 2013 IOP Publishing Ltd.

  8. Fish Locomotion: Recent Advances and New Directions

    Science.gov (United States)

    Lauder, George V.

    2015-01-01

    Research on fish locomotion has expanded greatly in recent years as new approaches have been brought to bear on a classical field of study. Detailed analyses of patterns of body and fin motion and the effects of these movements on water flow patterns have helped scientists understand the causes and effects of hydrodynamic patterns produced by swimming fish. Recent developments include the study of the center-of-mass motion of swimming fish and the use of volumetric imaging systems that allow three-dimensional instantaneous snapshots of wake flow patterns. The large numbers of swimming fish in the oceans and the vorticity present in fin and body wakes support the hypothesis that fish contribute significantly to the mixing of ocean waters. New developments in fish robotics have enhanced understanding of the physical principles underlying aquatic propulsion and allowed intriguing biological features, such as the structure of shark skin, to be studied in detail.

  9. Slipping slender bodies and enhanced flagellar locomotion

    Science.gov (United States)

    Man, Yi; Lauga, Eric

    2017-11-01

    In the biological world, many cells exploit slender appendages to swim, include numerous species of bacteria, algae and spermatozoa. A classical method to describe the flow field around such appendages is slender-body theory (SBT), which is often used to study flagellar motility in Newtonian fluids. However, biology environments are often rheologically complex due to the presence of polymers. These polymers generically phase-separate near rigid boundaries where low-viscosity fluid layers lead to effective slip on the surface. In this talk, we present an analytical derivation of SBT in the case where the no-slip boundary condition on the appendage is replaced by a Navier slip boundary condition. Our results demonstrate in particular a systematic reduction of the resistance coefficient of the slender filaments in their tangential direction, which leads to enhanced flagellar locomotion.

  10. Coupling of cytoskeleton functions for fibroblast locomotion

    DEFF Research Database (Denmark)

    Couchman, J R; Lenn, M; Rees, D A

    1985-01-01

    the cells to lose control of shape and organelle distribution even though forward protrusion continued unaffected. Cytoplasmic displacements shown by marker mitochondria correlated with adjacent fluctuations at the leading edge, and drug treatments which increased the amplitude of mitochondrial movements...... caused visible protrusions in projected positions at the leading edge. We conclude that fibroblast locomotion may be driven coordinately by a common set of motility mechanisms and that this coordination may be lost as a result of physical or pharmacological disturbance. Taking our evidence with results...... from other Laboratories, we propose the following cytoskeleton functions. (i) Protrusive activity, probably based on solation--gelation cycles of the actin based cytoskeleton and membrane recycling which provides cellular and membrane components for streaming through the cell body to the leading edge...

  11. Collective locomotion of non-swimmers

    Science.gov (United States)

    Lauga, Eric; Bartolo, Denis

    2009-03-01

    To achieve propulsion at low Reynolds number, a swimmer (e.g. a biological cell such as a bacterium, or a spermatozoon) must deform its shape in time in a way that is not invariant under time-reversal symmetry (non-reciprocal); this is Purcell's scallop theorem. We show here explicitly that there is no many-scallop theorem. Two active bodies undergoing reciprocal deformations - and therefore incapable of swimming when considered separately - can exploit hydrodynamic interaction to swim. If the bodies are polar, we also show that they experience effective long-range interactions. We derive our results analytically for a minimal dimers model, and generalize them to more complex geometries on the basis of symmetry and scaling arguments. Furthermore, we explain how such cooperative locomotion can be realized experimentally by shaking a collection of soft particles with a homogeneous external field, thereby making non-swimmers swim.

  12. Soft Snakes: Construction, Locomotion, and Control

    Science.gov (United States)

    Branyan, Callie; Courier, Taylor; Fleming, Chloe; Remaley, Jacquelin; Hatton, Ross; Menguc, Yigit

    We fabricated modular bidirectional silicone pneumatic actuators to build a soft snake robot, applying geometric models of serpenoid swimmers to identify theoretically optimal gaits to realize serpentine locomotion. With the introduction of magnetic connections and elliptical cross-sections in fiber-reinforced modules, we can vary the number of continuum segments in the snake body to achieve more supple serpentine motion in a granular media. The performance of these gaits is observed using a motion capture system and efficiency is assessed in terms of pressure input and net displacement. These gaits are optimized using our geometric soap-bubble method of gait optimization, demonstrating the applicability of this tool to soft robot control and coordination.

  13. Embodied Sensorimotor Interaction for Hexapod Locomotion

    DEFF Research Database (Denmark)

    Ambe, Yuichi; Aoi, Shinya; Nachstedt, Timo

    2016-01-01

    is still unclear. Recent studies in biology suggest that a functional motor output during walking is formed by the interaction between central pattern generators (CPGs) and sensory feedbacks. In this paper, we investigate the dynamics of a hexapod robot model whose legs are driven by distributed...... oscillators with a local sensory feedback from neuromechanical point of view. This feedback changes the oscillation period of the oscillator depending solely on the timing of the contact between the foot and the ground. The results of dynamic simulations and real robot experiments show that due to the local...... sensory feedback the robot produces continuous stable gaits depending on the locomotion speed as a result of self-organization, one of which are similar to those of insects. These results reveal that the neuromechanical interaction induced by the local sensory feedback plays an important role...

  14. Locomotion in simulated microgravity: gravity replacement loads

    Science.gov (United States)

    McCrory, Jean L.; Baron, Heidi A.; Balkin, Sandy; Cavanagh, Peter R.

    2002-01-01

    BACKGROUND: When an astronaut walks or runs on a treadmill in microgravity, a subject load device (SLD) is used to return him or her back to the treadmill belt. The gravity replacement load (GRL) in the SLD is transferred, via a harness, to the pelvis and/or the shoulders. This research compared comfort and ground reaction forces during treadmill running in a microgravity locomotion simulator at GRLs of 60%, 80%, and 100% of body weight (BW). Two harness designs (shoulder springs only (SSO) and waist and shoulder springs (WSS)) were used. HYPOTHESES: 1) The 100% BW gravity replacement load conditions would be comfortably tolerated and would result in larger ground reaction forces and loading rates than the lower load conditions, and 2) the WSS harness would be more comfortable than the SSO harness. METHODS: Using the Penn State Zero Gravity Locomotion Simulator (ZLS), 8 subjects ran at 2.0 m x s(-1) (4.5 mph) for 3 min at each GRL setting in each harness. Subjective ratings of harness comfort, ground reaction forces, and GRL data were collected during the final minute of exercise. RESULTS: The 100% BW loading conditions were comfortably tolerated (2.3 on a scale of 0-10), although discomfort increased as the GRL increased. There were no overall differences in perceived comfort between the two harnesses. The loading rates (27.1, 33.8, 39.1 BW x s(-1)) and the magnitudes of the first (1.0, 1.4, 1.6 BW) and second (1.3, 1.7, 1.9 BW) peaks of the ground reaction force increased with increasing levels (60, 80, 100% BW respectively) of GRL. CONCLUSIONS: Subjects were able to tolerate a GRL of 100% BW well. The magnitude of the ground reaction force peaks and the loading rate is directly related to the magnitude of the GRL.

  15. CPG-based Locomotion Controller Design for a Boxfish-like Robot

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2014-06-01

    Full Text Available This paper focuses on a Central Pattern Generator (CPG-based locomotion controller design for a boxfish-like robot. The bio-inspired controller is aimed at flexible switching in multiple 3D swimming patterns and exact attitude control of yaw and roll such that the robot will swim more like a real boxfish. The CPG network comprises two layers, the lower layer is the network of coupled linear oscillators and the upper is the transition layer where the lower-dimensional locomotion stimuli are transformed into the higher-dimensional control parameters serving for all the oscillators. Based on such a two-layer framework, flexible switching between multiple three-dimensional swimming patterns, such as swimming forwards/backwards, turning left/right, swimming upwards/downwards and rolling clockwise/counter-clockwise, can be simply realized by inputting different stimuli. Moreover, the stability of the CPG network is strictly proved to guarantee the intrinsic stability of the swimming patterns. As to exact attitude control, based on this open-loop CPG network and the sensory feedback from the Inertial Measurement Unit (IMU, a closed-loop CPG controller is advanced for yaw and roll control of the robotic fish for the first time. This CPG-based online attitude control for a robotic fish will greatly facilitate high-level practical underwater applications. A series of relevant experiments with the robotic fish are conducted systematically to validate the effectiveness and stability of the open-loop and closed-loop CPG controllers.

  16. How to find home backwards? Locomotion and inter-leg coordination during rearward walking of Cataglyphis fortis desert ants.

    Science.gov (United States)

    Pfeffer, Sarah E; Wahl, Verena L; Wittlinger, Matthias

    2016-07-15

    For insects, flexibility in the performance of terrestrial locomotion is a vital part of facing the challenges of their often unpredictable environment. Arthropods such as scorpions and crustaceans can switch readily from forward to backward locomotion, but in insects this behaviour seems to be less common and, therefore, is only poorly understood. Here we present an example of spontaneous and persistent backward walking in Cataglyphis desert ants that allows us to investigate rearward locomotion within a natural context. When ants find a food item that is too large to be lifted up and to be carried in a normal forward-faced orientation, they will drag the load walking backwards to their home nest. A detailed examination of this behaviour reveals a surprising flexibility of the locomotor output. Compared with forward walks with regular tripod coordination, no main coordination pattern can be assigned to rearward walks. However, we often observed leg-pair-specific stepping patterns. The front legs frequently step with small stride lengths, while the middle and the hind legs are characterized by less numerous but larger strides. But still, these specializations show no rigidly fixed leg coupling, nor are they strictly embedded within a temporal context; therefore, they do not result in a repetitive coordination pattern. The individual legs act as separate units, most likely to better maintain stability during backward dragging. © 2016. Published by The Company of Biologists Ltd.

  17. In-pipe micromachine locomotion via the inertial stepping principle

    Energy Technology Data Exchange (ETDEWEB)

    Yum, Young Jin [University of Ulsan, Ulsan (Korea, Republic of); Hwang, Han Sub [Suweon Science College, Suweon (Korea, Republic of); Kelemen, Michal; Maxim, Vladislav; Frankovsky, Peter [Technical University of Kosice, Kosice (Slovakia)

    2014-08-15

    This paper discusses an in-pipe inspection micromachine intended for locomotion inside a small diameter pipe. The micromachine locomotion is based on the inertial stepping principle, which utilizes the drive force of the two-body impact. The in-pipe micromachine contacts the pipe through the elastic bristles installed on the in-pipe machine and in two lines and crossways with respect to the micromachine axle. The paper describes the principle of locomotion and the dynamics by which the unknown of both the parameters and the relations are experimentally identified. Based on the results, a simulation model was created, and the results of the simulations were compared with experimental results.

  18. A survey report for the turning of biped locomotion robot

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Ichiro; Takanishi, Atsuo [Waseda Univ., Tokyo (Japan); Kume, Etsuo

    1992-12-01

    A mechanical design study of biped locomotion robots is going on at JAERI within the scope of the Human Acts Simulation Program (HASP). The design study at JAERI is of an arbitrarily mobile robot for inspection of nuclear facilities. A survey has been performed for collecting useful information from already existing biped locomotion robots. This is a survey report for the turning of biped locomotion robot: the WL-10R designed and developed at Waseda University. This report includes the control method of turning, machine model and control system. (author).

  19. 49 CFR 230.90 - Draw gear between steam locomotive and tender.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Draw gear between steam locomotive and tender. 230... Steam Locomotives and Tenders Draw Gear and Draft Systems § 230.90 Draw gear between steam locomotive and tender. (a) Maintenance and testing. The draw gear between the steam locomotive and tender...

  20. 49 CFR 231.16 - Steam locomotives used in switching service.

    Science.gov (United States)

    2010-10-01

    .... Side handholds shall be securely fastened with bolts or rivets. (e) Uncoupling levers—(1) Number. Two double levers, operative from either side. (2) Dimensions. (i) Handles of front-end levers shall be not... minimum clearance of 2 inches around handle. (ii) Rear-end levers shall extend across end of tender with...

  1. Switch mode power supply

    International Nuclear Information System (INIS)

    Kim, Hui Jun

    1993-06-01

    This book concentrates on switch mode power supply. It has four parts, which are introduction of switch mode power supply with DC-DC converter such as Buck converter boost converter, Buck-boost converter and PWM control circuit, explanation for SMPS with DC-DC converter modeling and power mode control, resonance converter like resonance switch, converter, multi resonance converter and series resonance and parallel resonance converters, basic test of SMPS with PWM control circuit, Buck converter, Boost converter, flyback converter, forward converter and IC for control circuit.

  2. BROOKHAVEN: Switched power

    International Nuclear Information System (INIS)

    Anon.

    1989-01-01

    Hosted by Brookhaven's Center for Accelerator Physics, a recent workshop on switched power techniques attracted a group of specialists to Shelter Island, New York, location of several important physics meetings, including the famous 1947 sessions which helped mould modern quantum electrodynamics. The current interest in switched power stemmed from a series of papers by W. Willis of CERN, starting in 1984. The idea is for stored electrical energy to be suddenly switched on to a transmission line, producing a very short (about 10 ps) electromagnetic pulse in a region traversed by a particle beam

  3. Electromechanical magnetization switching

    Energy Technology Data Exchange (ETDEWEB)

    Chudnovsky, Eugene M. [Department of Physics and Astronomy, Lehman College and Graduate School, The City University of New York, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589 (United States); Jaafar, Reem [Department of Mathematics, Engineering and Computer Science, LaGuardia Community College, The City University of New York, 31-10 Thomson Avenue, Long Island City, New York 11101 (United States)

    2015-03-14

    We show that the magnetization of a torsional oscillator that, in addition to the magnetic moment also possesses an electrical polarization, can be switched by the electric field that ignites mechanical oscillations at the frequency comparable to the frequency of the ferromagnetic resonance. The 180° switching arises from the spin-rotation coupling and is not prohibited by the different symmetry of the magnetic moment and the electric field as in the case of a stationary magnet. Analytical equations describing the system have been derived and investigated numerically. Phase diagrams showing the range of parameters required for the switching have been obtained.

  4. Electromechanical magnetization switching

    International Nuclear Information System (INIS)

    Chudnovsky, Eugene M.; Jaafar, Reem

    2015-01-01

    We show that the magnetization of a torsional oscillator that, in addition to the magnetic moment also possesses an electrical polarization, can be switched by the electric field that ignites mechanical oscillations at the frequency comparable to the frequency of the ferromagnetic resonance. The 180° switching arises from the spin-rotation coupling and is not prohibited by the different symmetry of the magnetic moment and the electric field as in the case of a stationary magnet. Analytical equations describing the system have been derived and investigated numerically. Phase diagrams showing the range of parameters required for the switching have been obtained

  5. JUNOS Enterprise Switching

    CERN Document Server

    Reynolds, Harry

    2009-01-01

    JUNOS Enterprise Switching is the only detailed technical book on Juniper Networks' new Ethernet-switching EX product platform. With this book, you'll learn all about the hardware and ASIC design prowess of the EX platform, as well as the JUNOS Software that powers it. Not only is this extremely practical book a useful, hands-on manual to the EX platform, it also makes an excellent study guide for certification exams in the JNTCP enterprise tracks. The authors have based JUNOS Enterprise Switching on their own Juniper training practices and programs, as well as the configuration, maintenanc

  6. Dynamic Locomotion With Four and Six-Legged Robots

    National Research Council Canada - National Science Library

    Buehler, M; Saranli, U; Papadopoulos, D; Koditschek, D

    2000-01-01

    .... The Scout II quadruped runs on flat ground in a bounding gait, and was motivated by an effort to understand the minimal mechanical design and control complexity for dynamically stable locomotion...

  7. A sensory-driven controller for quadruped locomotion.

    Science.gov (United States)

    Ferreira, César; Santos, Cristina P

    2017-02-01

    Locomotion of quadruped robots has not yet achieved the harmony, flexibility, efficiency and robustness of its biological counterparts. Biological research showed that spinal reflexes are crucial for a successful locomotion in the most varied terrains. In this context, the development of bio-inspired controllers seems to be a good way to move toward an efficient and robust robotic locomotion, by mimicking their biological counterparts. This contribution presents a sensory-driven controller designed for the simulated Oncilla quadruped robot. In the proposed reflex controller, movement is generated through the robot's interactions with the environment, and therefore, the controller is solely dependent on sensory information. The results show that the reflex controller is capable of producing stable quadruped locomotion with a regular stepping pattern. Furthermore, it is capable of dealing with slopes without changing the parameters and with small obstacles, overcoming them successfully. Finally, system robustness was verified by adding noise to sensors and actuators and also delays.

  8. Vibrational Locomotion Enabling Subsurface Exploration of Unconsolidated Regolith Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The idea of vibrational locomotion is based on vibrational-fluidization in ISRU reactor systems, which has proven very effective for regolith mixing. The vibrating...

  9. Test requirements of locomotive fuel tank blunt impact tests

    Science.gov (United States)

    2013-10-15

    The Federal Railroad Administrations Office of Research : and Development is conducting research into passenger : locomotive fuel tank crashworthiness. A series of impact tests : are planned to measure fuel tank deformation under two types : of dy...

  10. Crawling beneath the free surface: Water snail locomotion

    OpenAIRE

    Lee, Sungyon; Bush, John W. M.; Hosoi, A. E.; Lauga, Eric

    2008-01-01

    Land snails move via adhesive locomotion. Through muscular contraction and expansion of their foot, they transmit waves of shear stress through a thin layer of mucus onto a solid substrate. Since a free surface cannot support shear stress, adhesive locomotion is not a viable propulsion mechanism for water snails that travel inverted beneath the free surface. Nevertheless, the motion of the freshwater snail, Sorbeoconcha physidae, is reminiscent of that of its terrestrial counterparts, being g...

  11. Design of Mine Locomotive System Based on CAN Bus

    OpenAIRE

    Li Yuanhong; Zhang Quanzhu; Zhang Wenshan

    2017-01-01

    Based on CAN bus, this paper studies the system control and management system of locomotive in mine, analyzes the working principle of locomotive system, gives the CAN bus scheme, hardware circuit design and CAN communication protocol, and implements long-distance, high-reliability communication function and remote monitoring function. Experiments show that the auxiliary system based on CAN bus control easier, operation more secure, as well as improving the control performance and service lif...

  12. Locomotion in Lymphocytes is Altered by Differential PKC Isoform Expression

    Science.gov (United States)

    Sundaresan, A.; Risin, D.; Pellis, N. R.

    1999-01-01

    Lymphocyte locomotion is critical for proper elicitation of the immune response. Locomotion of immune cells via the interstitium is essential for optimal immune function during wound healing, inflammation and infection. There are conditions which alter lymphocyte locomotion and one of them is spaceflight. Lymphocyte locomotion is severely inhibited in true spaceflight (true microgravity) and in rotating wall vessel culture (modeled microgravity). When lymphocytes are activated prior to culture in modeled microgravity, locomotion is not inhibited and the levels are comparable to those of static cultured lymphocytes. When a phorbol ester (PMA) is used in modeled microgravity, lymphocyte locomotion is restored by 87%. This occurs regardless if PMA is added after culture in the rotating wall vessel or during culture. Inhibition of DNA synthesis also does not alter restoration of lymphocyte locomotion by PMA. PMA is a direct activator of (protein kinase C) PKC . When a calcium ionophore, ionomycin is used it does not possess any restorative properties towards locomotion either alone or collectively with PMA. Since PMA brings about restoration without help from calcium ionophores (ionomycin), it is infer-red that calcium independent PKC isoforms are involved. Changes were perceived in the protein levels of PKC 6 where levels of the protein were downregulated at 24,72 and 96 hours in untreated rotated cultures (modeled microgravity) compared to untreated static (1g) cultures. At 48 hours there is an increase in the levels of PKC & in the same experimental set up. Studies on transcriptional and translational patterns of calcium independent isoforms of PKC such as 8 and E are presented in this study.

  13. uv preilluminated gas switches

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, L.P.; Orham, E.L.; Stowers, I.F.; Braucht, J.R.

    1980-06-03

    We have designed, built, and characterized uv preilluminated gas switches for a trigger circuit and a low inductance discharge circuit. These switches have been incorporated into a 54 x 76 x 150 cm pulser module to produce a 1 Ma output current rising at 5 x 10/sup 12/ amps/sec with 1 ns jitter. Twenty such modules will be used on the Nova Inertial Confinement Fusion Laser System for plasma retropulse shutters.

  14. Switching power supply filter

    Science.gov (United States)

    Kumar, Prithvi R. (Inventor); Abare, Wayne (Inventor)

    1989-01-01

    A filter for a switching power supply. The filter includes a common mode inductor with coil configurations allowing differential mode current from a dc source to pass through but attenuating common mode noise from the power supply so that the noise does not reach the dc source. The invention also includes the use of feed through capacitors at the switching power supply input terminals to provide further high-frequency noise attenuation.

  15. uv preilluminated gas switches

    International Nuclear Information System (INIS)

    Bradley, L.P.; Orham, E.L.; Stowers, I.F.; Braucht, J.R.

    1980-01-01

    We have designed, built, and characterized uv preilluminated gas switches for a trigger circuit and a low inductance discharge circuit. These switches have been incorporated into a 54 x 76 x 150 cm pulser module to produce a 1 Ma output current rising at 5 x 10 12 amps/sec with 1 ns jitter. Twenty such modules will be used on the Nova Inertial Confinement Fusion Laser System for plasma retropulse shutters

  16. Photonics in switching

    CERN Document Server

    Midwinter, John E; Kelley, Paul

    1993-01-01

    Photonics in Switching provides a broad, balanced overview of the use of optics or photonics in switching, from materials and devices to system architecture. The chapters, each written by an expert in the field, survey the key technologies, setting them in context and highlighting their benefits and possible applications. This book is a valuable resource for those working in the communications industry, either at the professional or student level, who do not have extensive background knowledge or the underlying physics of the technology.

  17. Multi-modal locomotion: from animal to application

    International Nuclear Information System (INIS)

    Lock, R J; Burgess, S C; Vaidyanathan, R

    2014-01-01

    The majority of robotic vehicles that can be found today are bound to operations within a single media (i.e. land, air or water). This is very rarely the case when considering locomotive capabilities in natural systems. Utility for small robots often reflects the exact same problem domain as small animals, hence providing numerous avenues for biological inspiration. This paper begins to investigate the various modes of locomotion adopted by different genus groups in multiple media as an initial attempt to determine the compromise in ability adopted by the animals when achieving multi-modal locomotion. A review of current biologically inspired multi-modal robots is also presented. The primary aim of this research is to lay the foundation for a generation of vehicles capable of multi-modal locomotion, allowing ambulatory abilities in more than one media, surpassing current capabilities. By identifying and understanding when natural systems use specific locomotion mechanisms, when they opt for disparate mechanisms for each mode of locomotion rather than using a synergized singular mechanism, and how this affects their capability in each medium, similar combinations can be used as inspiration for future multi-modal biologically inspired robotic platforms. (topical review)

  18. Serotonin influences locomotion in the nudibranch mollusc Melibe leonina.

    Science.gov (United States)

    Lewis, Stefanie L; Lyons, Deborah E; Meekins, Tiffanie L; Newcomb, James M

    2011-06-01

    Serotonin (5-HT) influences locomotion in many animals, from flatworms to mammals. This study examined the effects of 5-HT on locomotion in the nudibranch mollusc Melibe leonina (Gould, 1852). M. leonina exhibits two modes of locomotion, crawling and swimming. Animals were bath-immersed in a range of concentrations of 5-HT or injected with various 5-HT solutions into the hemolymph and then monitored for locomotor activity. In contrast to other gastropods studied, M. leonina showed no significant effect of 5-HT on the distance crawled or the speed of crawling. However, the highest concentration (10(-3) mol l(-1) for bath immersion and 10(-5) mol l(-1) for injection) significantly increased the time spent swimming and the swimming speed. The 5-HT receptor antagonist methysergide inhibited the influence of 5-HT on the overall amount of swimming but not on swimming speed. These results suggest that 5-HT influences locomotion at the behavioral level in M. leonina. In conjunction with previous studies on the neural basis of locomotion in M. leonina, these results also suggest that this species is an excellent model system for investigating the 5-HT modulation of locomotion.

  19. Limited locomotive ability relaxed selective constraints on molluscs mitochondrial genomes.

    Science.gov (United States)

    Sun, Shao'e; Li, Qi; Kong, Lingfeng; Yu, Hong

    2017-09-06

    Mollusca are the second largest phylum in the animal kingdom with different types of locomotion. Some molluscs are poor-migrating, while others are free-moving or fast-swimming. Most of the energy required for locomotion is provided by mitochondria via oxidative phosphorylation. Here, we conduct a comparative genomic analysis of 256 molluscs complete mitochondrial genomes and evaluate the role of energetic functional constraints on the protein-coding genes, providing a new insight into mitochondrial DNA (mtDNA) evolution. The weakly locomotive molluscs, compared to strongly locomotive molluscs, show significantly higher Ka/Ks ratio, which suggest they accumulated more nonsynonymous mutations in mtDNA and have experienced more relaxed evolutionary constraints. Eleven protein-coding genes (CoxI, CoxII, ATP6, Cytb, ND1-6, ND4L) show significant difference for Ka/Ks ratios between the strongly and weakly locomotive groups. The relaxation of selective constraints on Atp8 arise in the common ancestor of bivalves, and the further relaxation occurred in marine bivalves lineage. Our study thus demonstrates that selective constraints relevant to locomotive ability play an essential role in evolution of molluscs mtDNA.

  20. A subset of interneurons required for Drosophila larval locomotion.

    Science.gov (United States)

    Yoshikawa, Shingo; Long, Hong; Thomas, John B

    2016-01-01

    Efforts to define the neural circuits generating locomotor behavior have produced an initial understanding of some of the components within the spinal cord, as well as a basic understanding of several invertebrate motor pattern generators. However, how these circuits are assembled during development is poorly understood. We are defining the neural circuit that generates larval locomotion in the genetically tractable fruit fly Drosophila melanogaster to study locomotor circuit development. Forward larval locomotion involves a stereotyped posterior-to-anterior segmental translocation of body wall muscle contraction and is generated by a relatively small number of identified muscles, motor and sensory neurons, plus an unknown number of the ~270 bilaterally-paired interneurons per segment of the 1st instar larva. To begin identifying the relevant interneurons, we have conditionally inactivated synaptic transmission of interneuron subsets and assayed for the effects on locomotion. From this screen we have identified a subset of 25 interneurons per hemisegment, called the lateral locomotor neurons (LLNs), that are required for locomotion. Both inactivation and constitutive activation of the LLNs disrupt locomotion, indicating that patterned output of the LLNs is required. By expressing a calcium indicator in the LLNs, we found that they display a posterior-to-anterior wave of activity within the CNS corresponding to the segmental translocation of the muscle contraction wave. Identification of the LLNs represents the first step toward elucidating the circuit generating larval locomotion. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Optical switching systems using nanostructures

    DEFF Research Database (Denmark)

    Stubkjær, Kristian

    2004-01-01

    High capacity multiservice optical networks require compact and efficient switches. The potential benefits of optical switch elements based on nanostructured material are reviewed considering various material systems.......High capacity multiservice optical networks require compact and efficient switches. The potential benefits of optical switch elements based on nanostructured material are reviewed considering various material systems....

  2. Understanding and Supporting Window Switching

    NARCIS (Netherlands)

    Tak, S.

    2011-01-01

    Switching between windows on a computer is a frequent activity, but finding and switching to the target window can be inefficient. This thesis aims to better un-derstand and support window switching. It explores two issues: (1) the lack of knowledge of how people currently interact with and switch

  3. Advanced underground Vehicle Power and Control: The locomotive Research Platform

    Energy Technology Data Exchange (ETDEWEB)

    Vehicle Projects LLC

    2003-01-28

    Develop a fuelcell mine locomotive with metal-hydride hydrogen storage. Test the locomotive for fundamental limitations preventing successful commercialization of hydride fuelcells in underground mining. During Phase 1 of the DOE-EERE sponsored project, FPI and its partner SNL, completed work on the development of a 14.4 kW fuelcell power plant and metal-hydride energy storage. An existing battery-electric locomotive with similar power requirements, minus the battery module, was used as the base vehicle. In March 2001, Atlas Copco Wagner of Portland, OR, installed the fuelcell power plant into the base vehicle and initiated integration of the system into the vehicle. The entire vehicle returned to Sandia in May 2001 for further development and integration. Initial system power-up took place in December 2001. A revision to the original contract, Phase 2, at the request of DOE Golden Field Office, established Vehicle Projects LLC as the new prime contractor,. Phase 2 allowed industry partners to conduct surface tests, incorporate enhancements to the original design by SNL, perform an extensive risk and safety analysis, and test the fuelcell locomotive underground under representative production mine conditions. During the surface tests one of the fuelcell stacks exhibited reduced power output resulting in having to replace both fuelcell stacks. The new stacks were manufactured with new and improved technology resulting in an increase of the gross power output from 14.4 kW to 17 kW. Further work by CANMET and Hatch Associates, an engineering consulting firm specializing in safety analysis for the mining industry, both under subcontract to Vehicle Projects LLC, established minimum requirements for underground testing. CANMET upgraded the Programmable Logic Control (PLC) software used to monitor and control the fuelcell power plant, taking into account locomotive operator's needs. Battery Electric, a South Africa manufacturer, designed and manufactured (at no cost

  4. Low inductance gas switching.

    Energy Technology Data Exchange (ETDEWEB)

    Chavez, Ray; Harjes, Henry Charles III; Wallace, Zachariah; Elizondo, Juan E.

    2007-10-01

    The laser trigger switch (LTS) is a key component in ZR-type pulsed power systems. In ZR, the pulse rise time through the LTS is > 200 ns and additional stages of pulse compression are required to achieve the desired <100 ns rise time. The inductance of the LTS ({approx}500nH) in large part determines the energy transfer time through the switch and there is much to be gained in improving system performance and reducing system costs by reducing this inductance. The current path through the cascade section of the ZR LTS is at a diameter of {approx} 6-inches which is certainly not optimal from an inductance point of view. The LTS connects components of much greater diameter (typically 4-5 feet). In this LDRD the viability of switch concepts in which the diameter of cascade section is greatly increased have been investigated. The key technical question to be answered was, will the desired multi-channel behavior be maintained in a cascade section of larger diameter. This LDRD proceeded in 2 distinct phases. The original plan for the LDRD was to develop a promising switch concept and then design, build, and test a moderate scale switch which would demonstrate the key features of the concept. In phase I, a switch concept which meet all electrical design criteria and had a calculated inductance of 150 nH was developed. A 1.5 MV test switch was designed and fabrication was initiated. The LDRD was then redirected due to budgetary concerns. The fabrication of the switch was halted and the focus of the LDRD was shifted to small scale experiments designed to answer the key technical question concerning multi-channel behavior. In phase II, the Multi-channel switch test bed (MCST) was designed and constructed. The purpose of MCST was to provide a versatile, fast turn around facility for the study the multi-channel electrical breakdown behavior of a ZR type cascade switch gap in a parameter space near that of a ZR LTS. Parameter scans on source impedance, gap tilt, gap spacing and

  5. Water surface locomotion in tropical canopy ants.

    Science.gov (United States)

    Yanoviak, S P; Frederick, D N

    2014-06-15

    Upon falling onto the water surface, most terrestrial arthropods helplessly struggle and are quickly eaten by aquatic predators. Exceptions to this outcome mostly occur among riparian taxa that escape by walking or swimming at the water surface. Here we document sustained, directional, neustonic locomotion (i.e. surface swimming) in tropical arboreal ants. We dropped 35 species of ants into natural and artificial aquatic settings in Peru and Panama to assess their swimming ability. Ten species showed directed surface swimming at speeds >3 body lengths s(-1), with some swimming at absolute speeds >10 cm s(-1). Ten other species exhibited partial swimming ability characterized by relatively slow but directed movement. The remaining species showed no locomotory control at the surface. The phylogenetic distribution of swimming among ant genera indicates parallel evolution and a trend toward negative association with directed aerial descent behavior. Experiments with workers of Odontomachus bauri showed that they escape from the water by directing their swimming toward dark emergent objects (i.e. skototaxis). Analyses of high-speed video images indicate that Pachycondyla spp. and O. bauri use a modified alternating tripod gait when swimming; they generate thrust at the water surface via synchronized treading and rowing motions of the contralateral fore and mid legs, respectively, while the hind legs provide roll stability. These results expand the list of facultatively neustonic terrestrial taxa to include various species of tropical arboreal ants. © 2014. Published by The Company of Biologists Ltd.

  6. Sensory modulation of movement, posture and locomotion.

    Science.gov (United States)

    Saradjian, A H

    2015-11-01

    During voluntary movement, there exists a well known functional sensory attenuation of afferent inputs, which allows us to discriminate between information related to our own movements and those arising from the external environment. This attenuation or 'gating' prevents some signals from interfering with movement elaboration and production. However, there are situations in which certain task-relevant sensory inputs may not be gated. This review begins by identifying the prevalent findings in the literature with specific regard to the somatosensory modality, and reviews the many cases of classical sensory gating phenomenon accompanying voluntary movement and their neural basis. This review also focuses on the newer axes of research that demonstrate that task-specific sensory information may be disinhibited or even facilitated during engagement in voluntary actions. Finally, a particular emphasis will be placed on postural and/or locomotor tasks involving strong somatosensory demands, especially for the setting of the anticipatory postural adjustments observed prior the initiation of locomotion. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  7. A radiation hard vacuum switch

    Science.gov (United States)

    Boettcher, G.E.

    1988-07-19

    A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction. 3 figs.

  8. EVALUATION OF DYNAMIC INDICATORS OF SIX-AXLE LOCOMOTIVE

    Directory of Open Access Journals (Sweden)

    S. V. Myamlin

    2015-04-01

    Full Text Available Purpose. The paper is devoted to dynamic characteristics evaluation of the locomotive with prospective design and determination the feasibility of its use on the Ukrainian railways. Methodology. The methods of mathematical and computer modeling of the dynamics of railway vehicles, as well as methods for the numerical integration of systems of ordinary nonlinear differential equations were used to solve the problem. Findings. The calculated diagram of a locomotive on three-axle bogies was built to solve the problem, and it is a system of rigid bodies connected by various elements of rheology. The mathematical model of the locomotive movement, allowing studying its spatial vibrations at driving on straight and curved sections of the track with random irregularities in plan and profile was developed with use of this calculated diagram. At compiling the mathematical model took into account both geometric (nonlinearity profile of the wheel roll surface and physical nonlinearity of the system (the work forces of dry friction, nonlinearity characteristics of interaction forces between wheels and rails. The multivariate calculations, which allowed assessing the dynamic qualities of the locomotive at its movement along straight and curved sections of the track, were realized with the use of computer modeling. The smoothness movement indicators of the locomotive in horizontal and vertical planes, frame strength, coefficients of vertical dynamics in the first and second stages of the suspension, the load factor of resistance against the derailment of the wheel from the rail were determined at the period of research. In addition, a comparison of the obtained results with similar characteristics is widely used on the Ukrainian railways in six-axle locomotive TE 116. The influence of speed and technical state of the track on the locomotive traffic safety was determined.Originality. A mathematical model of the spatial movement of a six-axle locomotive with

  9. INFORMATION-MEASURING TEST SYSTEM OF DIESEL LOCOMOTIVE HYDRAULIC TRANSMISSIONS

    Directory of Open Access Journals (Sweden)

    I. V. Zhukovytskyy

    2015-08-01

    Full Text Available Purpose. The article describes the process of developing the information-measuring test system of diesel locomotives hydraulic transmission, which gives the possibility to obtain baseline data to conduct further studies for the determination of the technical condition of diesel locomotives hydraulic transmission. The improvement of factory technology of post-repair tests of hydraulic transmissions by automating the existing hydraulic transmission test stands according to the specifications of the diesel locomotive repair enterprises was analyzed. It is achieved based on a detailed review of existing foreign information-measuring test systems for hydraulic transmission of diesel locomotives, BelAZ earthmover, aircraft tug, slag car, truck, BelAZ wheel dozer, some brands of tractors, etc. The problem for creation the information-measuring test systems for diesel locomotive hydraulic transmission is being solved, starting in the first place from the possibility of automation of the existing test stand of diesel locomotives hydraulic transmission at Dnipropetrovsk Diesel Locomotive Repair Plant "Promteplovoz". Methodology. In the work the researchers proposed the method to create a microprocessor automated system of diesel locomotives hydraulic transmission stand testing in the locomotive plant conditions. It acts by justifying the selection of the necessary sensors, as well as the application of the necessary hardware and software for information-measuring systems. Findings. Based on the conducted analysis there was grounded the necessity of improvement the plant hydraulic transmission stand testing by creating a microprocessor testing system, supported by the experience of developing such systems abroad. Further research should be aimed to improve the accuracy and frequency of data collection by adopting the more modern and reliable sensors in tandem with the use of filtering software for electromagnetic and other interference. Originality. The

  10. Problems of locomotive wheel wear in fleet replacement

    Directory of Open Access Journals (Sweden)

    L.P. Lingaytis

    2013-08-01

    Full Text Available Purpose. To conduct a research and find out the causes of defects appearing on the wheel thread of freight locomotives 2М62 and SIEMENS ER20CF. Methodology. To find the ways to solve this problem comparing the locomotive designs and their operating conditions. Findings. After examining the nature of the wheel wear the main difference was found: in locomotives of the 2M62 line wears the wheel flange, and in the locomotives SIEMENS ER20CF – the tread surface. After installation on the 2M62 locomotive the lubrication system of flanges their wear rate significantly decreased. On the new freight locomotives SIEMENS ER20CF the flange lubrication systems of the wheel set have been already installed at the factory, however the wheel thread is wearing. As for locomotives 2M62, and on locomotives SIEMENS ER20CF most wear profile skating wheels of the first wheel set. On both locomotive lines the 2М62 and the SIEMENS ER20CF the tread profile of the first wheel set most of all is subject to the wear. After reaching the 170 000 km run, the tread surface of some wheels begins to crumble. There was a suspicion that the reason for crumb formation of the wheel surface may be insufficient or excessive wheel hardness or its chemical composition. In order to confirm or deny this suspicion the following studies were conducted: the examination of the rim surface, the study of the wheel metal hardness and the document analysis of the wheel production and their comparison with the results of wheel hardness measurement. Practical value. The technical condition of locomotives is one of the bases of safety and reliability of the rolling stock. The reduction of the wheel wear significantly reduces the operating costs of railway transport. After study completion it was found that there was no evidence to suggest that the ratio of the wheel-rail hardness could be the cause of the wheel surface crumbling.

  11. Hybrid Locomotion Evaluation for a Novel Amphibious Spherical Robot

    Directory of Open Access Journals (Sweden)

    Huiming Xing

    2018-01-01

    Full Text Available We describe the novel, multiply gaited, vectored water-jet, hybrid locomotion-capable, amphibious spherical robot III (termed ASR-III featuring a wheel-legged, water-jet composite driving system incorporating a lifting and supporting wheel mechanism (LSWM and mechanical legs with a water-jet thruster. The LSWM allows the ASR-III to support the body and slide flexibly on smooth (flat terrain. The composite driving system facilitates two on-land locomotion modes (sliding and walking and underwater locomotion mode with vectored thrusters, improving adaptability to the amphibious environment. Sliding locomotion improves the stability and maneuverability of ASR-III on smooth flat terrain, whereas walking locomotion allows ASR-III to conquer rough terrain. We used both forward and reverse kinematic models to evaluate the walking and sliding gait efficiency. The robot can also realize underwater locomotion with four vectored water-jet thrusters, and is capable of forward motion, heading angle control and depth control. We evaluated LSWM efficiency and the sliding velocities associated with varying extensions of the LSWM. To explore gait stability and mobility, we performed on-land experiments on smooth flat terrain to define the optimal stride length and frequency. We also evaluated the efficacy of waypoint tracking when the sliding gait was employed, using a closed-loop proportional-integral-derivative (PID control mechanism. Moreover, experiments of forward locomotion, heading angle control and depth control were conducted to verify the underwater performance of ASR-III. Comparison of the previous robot and ASR-III demonstrated the ASR-III had better amphibious motion performance.

  12. Human Locomotion in Hypogravity: From Basic Research to Clinical Applications

    Directory of Open Access Journals (Sweden)

    Francesco Lacquaniti

    2017-11-01

    Full Text Available We have considerable knowledge about the mechanisms underlying compensation of Earth gravity during locomotion, a knowledge obtained from physiological, biomechanical, modeling, developmental, comparative, and paleoanthropological studies. By contrast, we know much less about locomotion and movement in general under sustained hypogravity. This lack of information poses a serious problem for human space exploration. In a near future humans will walk again on the Moon and for the first time on Mars. It would be important to predict how they will move around, since we know that locomotion and mobility in general may be jeopardized in hypogravity, especially when landing after a prolonged weightlessness of the space flight. The combination of muscle weakness, of wearing a cumbersome spacesuit, and of maladaptive patterns of locomotion in hypogravity significantly increase the risk of falls and injuries. Much of what we currently know about locomotion in hypogravity derives from the video archives of the Apollo missions on the Moon, the experiments performed with parabolic flight or with body weight support on Earth, and the theoretical models. These are the topics of our review, along with the issue of the application of simulated hypogravity in rehabilitation to help patients with deambulation problems. We consider several issues that are common to the field of space science and clinical rehabilitation: the general principles governing locomotion in hypogravity, the methods used to reduce gravity effects on locomotion, the extent to which the resulting behavior is comparable across different methods, the important non-linearities of several locomotor parameters as a function of the gravity reduction, the need to use multiple methods to obtain reliable results, and the need to tailor the methods individually based on the physiology and medical history of each person.

  13. Human Locomotion in Hypogravity: From Basic Research to Clinical Applications

    Science.gov (United States)

    Lacquaniti, Francesco; Ivanenko, Yury P.; Sylos-Labini, Francesca; La Scaleia, Valentina; La Scaleia, Barbara; Willems, Patrick A.; Zago, Myrka

    2017-01-01

    We have considerable knowledge about the mechanisms underlying compensation of Earth gravity during locomotion, a knowledge obtained from physiological, biomechanical, modeling, developmental, comparative, and paleoanthropological studies. By contrast, we know much less about locomotion and movement in general under sustained hypogravity. This lack of information poses a serious problem for human space exploration. In a near future humans will walk again on the Moon and for the first time on Mars. It would be important to predict how they will move around, since we know that locomotion and mobility in general may be jeopardized in hypogravity, especially when landing after a prolonged weightlessness of the space flight. The combination of muscle weakness, of wearing a cumbersome spacesuit, and of maladaptive patterns of locomotion in hypogravity significantly increase the risk of falls and injuries. Much of what we currently know about locomotion in hypogravity derives from the video archives of the Apollo missions on the Moon, the experiments performed with parabolic flight or with body weight support on Earth, and the theoretical models. These are the topics of our review, along with the issue of the application of simulated hypogravity in rehabilitation to help patients with deambulation problems. We consider several issues that are common to the field of space science and clinical rehabilitation: the general principles governing locomotion in hypogravity, the methods used to reduce gravity effects on locomotion, the extent to which the resulting behavior is comparable across different methods, the important non-linearities of several locomotor parameters as a function of the gravity reduction, the need to use multiple methods to obtain reliable results, and the need to tailor the methods individually based on the physiology and medical history of each person. PMID:29163225

  14. Energy reversible switching from amorphous metal based nanoelectromechanical switch

    KAUST Repository

    Mayet, Abdulilah M.

    2013-08-01

    We report observation of energy reversible switching from amorphous metal based nanoelectromechanical (NEM) switch. For ultra-low power electronics, NEM switches can be used as a complementary switching element in many nanoelectronic system applications. Its inherent zero power consumption because of mechanical detachment is an attractive feature. However, its operating voltage needs to be in the realm of 1 volt or lower. Appropriate design and lower Young\\'s modulus can contribute achieving lower operating voltage. Therefore, we have developed amorphous metal with low Young\\'s modulus and in this paper reporting the energy reversible switching from a laterally actuated double electrode NEM switch. © 2013 IEEE.

  15. Stabilization of cat paw trajectory during locomotion.

    Science.gov (United States)

    Klishko, Alexander N; Farrell, Bradley J; Beloozerova, Irina N; Latash, Mark L; Prilutsky, Boris I

    2014-09-15

    We investigated which of cat limb kinematic variables during swing of regular walking and accurate stepping along a horizontal ladder are stabilized by coordinated changes of limb segment angles. Three hypotheses were tested: 1) animals stabilize the entire swing trajectory of specific kinematic variables (performance variables); and 2) the level of trajectory stabilization is similar between regular and ladder walking and 3) is higher for forelimbs compared with hindlimbs. We used the framework of the uncontrolled manifold (UCM) hypothesis to quantify the structure of variance of limb kinematics in the limb segment orientation space across steps. Two components of variance were quantified for each potential performance variable, one of which affected it ("bad variance," variance orthogonal to the UCM, VORT) while the other one did not ("good variance," variance within the UCM, VUCM). The analysis of five candidate performance variables revealed that cats during both locomotor behaviors stabilize 1) paw vertical position during the entire swing (VUCM > VORT, except in mid-hindpaw swing of ladder walking) and 2) horizontal paw position in initial and terminal swing (except for the entire forepaw swing of regular walking). We also found that the limb length was typically stabilized in midswing, whereas limb orientation was not (VUCM ≤ VORT) for both limbs and behaviors during entire swing. We conclude that stabilization of paw position in early and terminal swing enables accurate and stable locomotion, while stabilization of vertical paw position in midswing helps paw clearance. This study is the first to demonstrate the applicability of the UCM-based analysis to nonhuman movement. Copyright © 2014 the American Physiological Society.

  16. Stabilization of cat paw trajectory during locomotion

    Science.gov (United States)

    Klishko, Alexander N.; Farrell, Bradley J.; Beloozerova, Irina N.; Latash, Mark L.

    2014-01-01

    We investigated which of cat limb kinematic variables during swing of regular walking and accurate stepping along a horizontal ladder are stabilized by coordinated changes of limb segment angles. Three hypotheses were tested: 1) animals stabilize the entire swing trajectory of specific kinematic variables (performance variables); and 2) the level of trajectory stabilization is similar between regular and ladder walking and 3) is higher for forelimbs compared with hindlimbs. We used the framework of the uncontrolled manifold (UCM) hypothesis to quantify the structure of variance of limb kinematics in the limb segment orientation space across steps. Two components of variance were quantified for each potential performance variable, one of which affected it (“bad variance,” variance orthogonal to the UCM, VORT) while the other one did not (“good variance,” variance within the UCM, VUCM). The analysis of five candidate performance variables revealed that cats during both locomotor behaviors stabilize 1) paw vertical position during the entire swing (VUCM > VORT, except in mid-hindpaw swing of ladder walking) and 2) horizontal paw position in initial and terminal swing (except for the entire forepaw swing of regular walking). We also found that the limb length was typically stabilized in midswing, whereas limb orientation was not (VUCM ≤ VORT) for both limbs and behaviors during entire swing. We conclude that stabilization of paw position in early and terminal swing enables accurate and stable locomotion, while stabilization of vertical paw position in midswing helps paw clearance. This study is the first to demonstrate the applicability of the UCM-based analysis to nonhuman movement. PMID:24899676

  17. Microfabricated triggered vacuum switch

    Science.gov (United States)

    Roesler, Alexander W [Tijeras, NM; Schare, Joshua M [Albuquerque, NM; Bunch, Kyle [Albuquerque, NM

    2010-05-11

    A microfabricated vacuum switch is disclosed which includes a substrate upon which an anode, cathode and trigger electrode are located. A cover is sealed over the substrate under vacuum to complete the vacuum switch. In some embodiments of the present invention, a metal cover can be used in place of the trigger electrode on the substrate. Materials used for the vacuum switch are compatible with high vacuum, relatively high temperature processing. These materials include molybdenum, niobium, copper, tungsten, aluminum and alloys thereof for the anode and cathode. Carbon in the form of graphitic carbon, a diamond-like material, or carbon nanotubes can be used in the trigger electrode. Channels can be optionally formed in the substrate to mitigate against surface breakdown.

  18. Switching power supply

    Science.gov (United States)

    Mihalka, A.M.

    1984-06-05

    The invention is a repratable capacitor charging, switching power supply. A ferrite transformer steps up a dc input. The transformer primary is in a full bridge configuration utilizing power MOSFETs as the bridge switches. The transformer secondary is fed into a high voltage, full wave rectifier whose output is connected directly to the energy storage capacitor. The transformer is designed to provide adequate leakage inductance to limit capacitor current. The MOSFETs are switched to the variable frequency from 20 to 50 kHz to charge a capacitor from 0.6 kV. The peak current in a transformer primary and secondary is controlled by increasing the pulse width as the capacitor charges. A digital ripple counter counts pulses and after a preselected desired number is reached an up-counter is clocked.

  19. Optical computer switching network

    Science.gov (United States)

    Clymer, B.; Collins, S. A., Jr.

    1985-01-01

    The design for an optical switching system for minicomputers that uses an optical spatial light modulator such as a Hughes liquid crystal light valve is presented. The switching system is designed to connect 80 minicomputers coupled to the switching system by optical fibers. The system has two major parts: the connection system that connects the data lines by which the computers communicate via a two-dimensional optical matrix array and the control system that controls which computers are connected. The basic system, the matrix-based connecting system, and some of the optical components to be used are described. Finally, the details of the control system are given and illustrated with a discussion of timing.

  20. Optical Packet Switching Demostrator

    DEFF Research Database (Denmark)

    Mortensen, Brian Bach; Berger, Michael Stübert

    2002-01-01

    In the IST project DAVID (data and voice integration over DWDM) work is carried out defining possible architectures of future optical packet switched networks. The feasibility of the architecture is to be verified in a demonstration set-up. This article describes the demonstrator set-up and the m......In the IST project DAVID (data and voice integration over DWDM) work is carried out defining possible architectures of future optical packet switched networks. The feasibility of the architecture is to be verified in a demonstration set-up. This article describes the demonstrator set...

  1. Plasma Switch Development.

    Science.gov (United States)

    1984-06-08

    ACCION NO. 3. RCIPIENT’S CATALOG NUMBER 4. TITLE (and Subtitle) 5. TYPE OF REPORT & PERIOD COVERED PLASMA SWITCH DEVELOPMENT Final Report: 02/26/82 thru...with an inductive energy store. At present, the are summarized state-of-he- art of high-power repetitive opening or doming switches is limited to...Alexandria, VA 22304. Figure 7 Is a circuit diagram of the proposed system. The desired load pulse parameters art -100- e References 1. R.D. Ford, 0. Jenkins

  2. Bearingless switched reluctance motor

    Science.gov (United States)

    Morrison, Carlos R. (Inventor)

    2004-01-01

    A switched reluctance motor has a stator with a first set of poles directed toward levitating a rotor horizontally within the stator. A disc shaped portion of a hybrid rotor is affected by the change in flux relative to the current provided at these levitation poles. A processor senses the position of the rotor and changes the flux to move the rotor toward center of the stator. A second set of poles of the stator are utilized to impart torque upon a second portion of the rotor. These second set of poles are driven in a traditional switched reluctance manner by the processor.

  3. Locomotive syndrome in the elderly: translation, cultural adaptation, and Brazilian validation of the tool 25-Question Geriatric Locomotive Function Scale.

    Science.gov (United States)

    Tavares, Daniela Regina Brandão; Santos, Fania Cristina

    The term Locomotive Syndrome refers to conditions in which the elderly are at high risk of inability to ambulate due to problems in locomotor system. For Locomotive Syndrome screening, the 25-Question Geriatric Locomotive Function Scale was created. The objective here was to translate, adapt culturally to Brazil, and study the psychometric properties of 25-Question Geriatric Locomotive Function Scale. The translation and cultural adaptation of 25-Question Geriatric Locomotive Function Scale were carried out, thus resulting in GLFS 25-P, whose psychometric properties were analyzed in a sample of 100 elderly subjects. Sociodemographic data on pain, falls, self-perceived health and basic and instrumental functionalities were determined. GLFS 25-P was applied three times: in one same day by two interviewers, and after 15 days, again by the first interviewer. GLFS 25-P showed a high internal consistency value according to Cronbach's alpha coefficient (0.942), and excellent reproducibility, according to intraclass correlation, with interobserver and intraobserver values of 97.6% and 98.4%, respectively (p<0.01). Agreements for each item of the instrument were considerable (between 0.248 and 0.673), according to Kappa statistic. In its validation, according to the Pearson's coefficient, regular and good correlations were obtained for the basic (BADL) and instrumental (IADL) activities of daily living, respectively (p<0.01). Statistically significant associations with chronic pain (p<0.001), falls (p=0.02) and self-perceived health (p<0.001) were found. A multivariate analysis showed a significantly higher risk of Locomotive Syndrome in the presence of chronic pain (OR 15.92, 95% CI 3.08-82.27) and with a worse self-perceived health (OR 0.23, 95% CI 0.07-0.79). GLFS 25-P proved to be a reliable and valid tool in Locomotive Syndrome screening for the elderly population. Copyright © 2016. Published by Elsevier Editora Ltda.

  4. Obstacle Avoidance in Groping Locomotion of a Humanoid Robot

    Directory of Open Access Journals (Sweden)

    Masahiro Ohka

    2008-11-01

    Full Text Available This paper describes the development of an autonomous obstacle-avoidance method that operates in conjunction with groping locomotion on the humanoid robot Bonten-Maru II. Present studies on groping locomotion consist of basic research in which humanoid robot recognizes its surroundings by touching and groping with its arm on the flat surface of a wall. The robot responds to the surroundings by performing corrections to its orientation and locomotion direction. During groping locomotion, however, the existence of obstacles within the correction area creates the possibility of collisions. The objective of this paper is to develop an autonomous method to avoid obstacles in the correction area by applying suitable algorithms to the humanoid robot's control system. In order to recognize its surroundings, six-axis force sensors were attached to both robotic arms as end effectors for force control. The proposed algorithm refers to the rotation angle of the humanoid robot's leg joints due to trajectory generation. The algorithm relates to the groping locomotion via the measured groping angle and motions of arms. Using Bonten-Maru II, groping experiments were conducted on a wall's surface to obtain wall orientation data. By employing these data, the humanoid robot performed the proposed method autonomously to avoid an obstacle present in the correction area. Results indicate that the humanoid robot can recognize the existence of an obstacle and avoid it by generating suitable trajectories in its legs.

  5. Two-fluid model for locomotion under self-confinement

    Science.gov (United States)

    Reigh, Shang Yik; Lauga, Eric

    2017-09-01

    The bacterium Helicobacter pylori causes ulcers in the stomach of humans by invading mucus layers protecting epithelial cells. It does so by chemically changing the rheological properties of the mucus from a high-viscosity gel to a low-viscosity solution in which it may self-propel. We develop a two-fluid model for this process of swimming under self-generated confinement. We solve exactly for the flow and the locomotion speed of a spherical swimmer located in a spherically symmetric system of two Newtonian fluids whose boundary moves with the swimmer. We also treat separately the special case of an immobile outer fluid. In all cases, we characterize the flow fields, their spatial decay, and the impact of both the viscosity ratio and the degree of confinement on the locomotion speed of the model swimmer. The spatial decay of the flow retains the same power-law decay as for locomotion in a single fluid but with a decreased magnitude. Independent of the assumption chosen to characterize the impact of confinement on the actuation applied by the swimmer, its locomotion speed always decreases with an increase in the degree of confinement. Our modeling results suggest that a low-viscosity region of at least six times the effective swimmer size is required to lead to swimming with speeds similar to locomotion in an infinite fluid, corresponding to a region of size above ≈25 μ m for Helicobacter pylori.

  6. Ultrafast gas switching experiments

    International Nuclear Information System (INIS)

    Frost, C.A.; Martin, T.H.; Patterson, P.E.; Rinehart, L.F.; Rohwein, G.J.; Roose, L.D.; Aurand, J.F.; Buttram, M.T.

    1993-01-01

    We describe recent experiments which studied the physics of ultrafast gas breakdown under the extreme overvoltages which occur when a high pressure gas switch is pulse charged to hundreds of kV in 1 ns or less. The highly overvolted peaking gaps produce powerful electromagnetic pulses with risetimes Khz at > 100 kV/m E field

  7. Photonic MEMS switch applications

    Science.gov (United States)

    Husain, Anis

    2001-07-01

    As carriers and service providers continue their quest for profitable network solutions, they have shifted their focus from raw bandwidth to rapid provisioning, delivery and management of revenue generating services. Inherently transparent to data rate the transmission wavelength and data format, MEMS add scalability, reliability, low power and compact size providing flexible solutions to the management and/or fiber channels in long haul, metro, and access networks. MEMS based photonic switches have gone from the lab to commercial availability and are now currently in carrier trials and volume production. 2D MEMS switches offer low up-front deployment costs while remaining scalable to large arrays. They allow for transparent, native protocol transmission. 2D switches enable rapid service turn-up and management for many existing and emerging revenue rich services such as storage connectivity, optical Ethernet, wavelength leasing and optical VPN. As the network services evolve, the larger 3D MEMS switches, which provide greater scalability and flexibility, will become economically viable to serve the ever-increasing needs.

  8. Search and switching costs

    NARCIS (Netherlands)

    Siekman, Wilhelm Henricus

    2016-01-01

    This thesis analyses markets with search and with switching costs. It provides insights in several important issues in search markets, including how loss aversion may affect consumer behavior and firm conduct, and how prices, welfare, and profits may change when an intermediating platform orders

  9. The Octopus switch

    NARCIS (Netherlands)

    Havinga, Paul J.M.

    2000-01-01

    This chapter1 discusses the interconnection architecture of the Mobile Digital Companion. The approach to build a low-power handheld multimedia computer presented here is to have autonomous, reconfigurable modules such as network, video and audio devices, interconnected by a switch rather than by a

  10. Stochastic Switching Dynamics

    DEFF Research Database (Denmark)

    Simonsen, Maria

    mode control. It is investigated how to understand and interpret solutions to models of switched systems, which are exposed to discontinuous dynamics and uncertainties (primarily) in the form of white noise. The goal is to gain knowledge about the performance of the system by interpreting the solution...

  11. Coupler dynamic performance analysis of heavy haul locomotives

    Science.gov (United States)

    Ma, Weihua; Luo, Shihui; Song, Rongrong

    2012-09-01

    In this paper, a train dynamic model was developed to study the dynamic performance of heavy haul locomotives, taking into account the use of different coupler and buffer systems under conditions of severe longitudinal coupler compressive forces. The model consists of four locomotives each having 38 independent degrees of freedom and one dummy freight vehicle connected to each other by couplers and buffers. Simulation results showed that the longitudinal coupler compressive forces withstood by large rotation angle couplers with coupler shoulders were larger than those withstood by small rotation angle couplers. The results obtained for the large rotation angle coupler model showed that it had higher safety curve negotiation speeds. Due to the smaller static impedance, it was found that large capacity elastic clay (or cement) buffers cannot satisfy the requirement of heavy haul locomotives during cycle braking in long heavy downgraded tracks; the use of friction clay buffers can solve this problem.

  12. Molecular Rotors as Switches

    Directory of Open Access Journals (Sweden)

    Kang L. Wang

    2012-08-01

    Full Text Available The use of a functional molecular unit acting as a state variable provides an attractive alternative for the next generations of nanoscale electronics. It may help overcome the limits of conventional MOSFETd due to their potential scalability, low-cost, low variability, and highly integratable characteristics as well as the capability to exploit bottom-up self-assembly processes. This bottom-up construction and the operation of nanoscale machines/devices, in which the molecular motion can be controlled to perform functions, have been studied for their functionalities. Being triggered by external stimuli such as light, electricity or chemical reagents, these devices have shown various functions including those of diodes, rectifiers, memories, resonant tunnel junctions and single settable molecular switches that can be electronically configured for logic gates. Molecule-specific electronic switching has also been reported for several of these device structures, including nanopores containing oligo(phenylene ethynylene monolayers, and planar junctions incorporating rotaxane and catenane monolayers for the construction and operation of complex molecular machines. A specific electrically driven surface mounted molecular rotor is described in detail in this review. The rotor is comprised of a monolayer of redox-active ligated copper compounds sandwiched between a gold electrode and a highly-doped P+ Si. This electrically driven sandwich-type monolayer molecular rotor device showed an on/off ratio of approximately 104, a read window of about 2.5 V, and a retention time of greater than 104 s. The rotation speed of this type of molecular rotor has been reported to be in the picosecond timescale, which provides a potential of high switching speed applications. Current-voltage spectroscopy (I-V revealed a temperature-dependent negative differential resistance (NDR associated with the device. The analysis of the device

  13. Quantitative locomotion study of freely swimming micro-organisms using laser diffraction.

    Science.gov (United States)

    Magnes, Jenny; Susman, Kathleen; Eells, Rebecca

    2012-10-25

    Soil and aquatic microscopic organisms live and behave in a complex three-dimensional environment. Most studies of microscopic organism behavior, in contrast, have been conducted using microscope-based approaches, which limit the movement and behavior to a narrow, nearly two-dimensional focal field.(1) We present a novel analytical approach that provides real-time analysis of freely swimming C. elegans in a cuvette without dependence on microscope-based equipment. This approach consists of tracking the temporal periodicity of diffraction patterns generated by directing laser light through the cuvette. We measure oscillation frequencies for freely swimming nematodes. Analysis of the far-field diffraction patterns reveals clues about the waveforms of the nematodes. Diffraction is the process of light bending around an object. In this case light is diffracted by the organisms. The light waves interfere and can form a diffraction pattern. A far-field, or Fraunhofer, diffraction pattern is formed if the screen-to-object distance is much larger than the diffracting object. In this case, the diffraction pattern can be calculated (modeled) using a Fourier transform.(2) C. elegans are free-living soil-dwelling nematodes that navigate in three dimensions. They move both on a solid matrix like soil or agar in a sinusoidal locomotory pattern called crawling and in liquid in a different pattern called swimming.(3) The roles played by sensory information provided by mechanosensory, chemosensory, and thermosensory cells that govern plastic changes in locomotory patterns and switches in patterns are only beginning to be elucidated.(4) We describe an optical approach to measuring nematode locomotion in three dimensions that does not require a microscope and will enable us to begin to explore the complexities of nematode locomotion under different conditions.

  14. Postural dependence of human locomotion during gait initiation.

    Science.gov (United States)

    Mille, Marie-Laure; Simoneau, Martin; Rogers, Mark W

    2014-12-15

    The initiation of human walking involves postural motor actions for body orientation and balance stabilization that must be effectively integrated with locomotion to allow safe and efficient transport. Our ability to coordinately adapt these functions to environmental or bodily changes through error-based motor learning is essential to effective performance. Predictive compensations for postural perturbations through anticipatory postural adjustments (APAs) that stabilize mediolateral (ML) standing balance normally precede and accompany stepping. The temporal sequencing between these events may involve neural processes that suppress stepping until the expected stability conditions are achieved. If so, then an unexpected perturbation that disrupts the ML APAs should delay locomotion. This study investigated how the central nervous system (CNS) adapts posture and locomotion to perturbations of ML standing balance. Healthy human adults initiated locomotion while a resistance force was applied at the pelvis to perturb posture. In experiment 1, using random perturbations, step onset timing was delayed relative to the APA onset indicating that locomotion was withheld until expected stability conditions occurred. Furthermore, stepping parameters were adapted with the APAs indicating that motor prediction of the consequences of the postural changes likely modified the step motor command. In experiment 2, repetitive postural perturbations induced sustained locomotor aftereffects in some parameters (i.e., step height), immediate but rapidly readapted aftereffects in others, or had no aftereffects. These results indicated both rapid but transient reactive adaptations in the posture and gait assembly and more durable practice-dependent changes suggesting feedforward adaptation of locomotion in response to the prevailing postural conditions. Copyright © 2014 the American Physiological Society.

  15. Control synthesis of switched systems

    CERN Document Server

    Zhao, Xudong; Niu, Ben; Wu, Tingting

    2017-01-01

    This book offers its readers a detailed overview of the synthesis of switched systems, with a focus on switching stabilization and intelligent control. The problems investigated are not only previously unsolved theoretically but also of practical importance in many applications: voltage conversion, naval piloting and navigation and robotics, for example. The book considers general switched-system models and provides more efficient design methods to bring together theory and application more closely than was possible using classical methods. It also discusses several different classes of switched systems. For general switched linear systems and switched nonlinear systems comprising unstable subsystems, it introduces novel ideas such as invariant subspace theory and the time-scheduled Lyapunov function method of designing switching signals to stabilize the underlying systems. For some typical switched nonlinear systems affected by various complex dynamics, the book proposes novel design approaches based on inte...

  16. Soft swimming: exploiting deformable interfaces for low reynolds number locomotion.

    Science.gov (United States)

    Trouilloud, Renaud; Yu, Tony S; Hosoi, A E; Lauga, Eric

    2008-07-25

    Reciprocal movement cannot be used for locomotion at low Reynolds number in an infinite fluid or near a rigid surface. Here we show that this limitation is relaxed for a body performing reciprocal motions near a deformable interface. Using physical arguments and scaling relationships, we show that the nonlinearities arising from reciprocal flow-induced interfacial deformation rectify the periodic motion of the swimmer, leading to locomotion. Such a strategy can be used to move toward, away from, and parallel to any deformable interface as long as the length scales involved are smaller than intrinsic scales, which we identify. A macroscale experiment of flapping motion near a free surface illustrates this new result.

  17. Economic aspects of advanced coal-fired gas turbine locomotives

    Science.gov (United States)

    Liddle, S. G.; Bonzo, B. B.; Houser, B. C.

    1983-01-01

    Increases in the price of such conventional fuels as Diesel No. 2, as well as advancements in turbine technology, have prompted the present economic assessment of coal-fired gas turbine locomotive engines. A regenerative open cycle internal combustion gas turbine engine may be used, given the development of ceramic hot section components. Otherwise, an external combustion gas turbine engine appears attractive, since although its thermal efficiency is lower than that of a Diesel engine, its fuel is far less expensive. Attention is given to such a powerplant which will use a fluidized bed coal combustor. A life cycle cost analysis yields figures that are approximately half those typical of present locomotive engines.

  18. Decoding the organization of spinal circuits that control locomotion

    Science.gov (United States)

    Kiehn, Ole

    2016-01-01

    Unravelling the functional operation of neuronal networks and linking cellular activity to specific behavioural outcomes are among the biggest challenges in neuroscience. In this broad field of research, substantial progress has been made in studies of the spinal networks that control locomotion. Through united efforts using electrophysiological and molecular genetic network approaches and behavioural studies in phylogenetically diverse experimental models, the organization of locomotor networks has begun to be decoded. The emergent themes from this research are that the locomotor networks have a modular organization with distinct transmitter and molecular codes and that their organization is reconfigured with changes to the speed of locomotion or changes in gait. PMID:26935168

  19. Review of opening switch technology

    International Nuclear Information System (INIS)

    Kristiansen, M.; Schoenbach, K.M.; Schaefer, G.

    1984-01-01

    Review of opening switch technology is given. Classification of open switches applied in pulsed power technology is presented. The most familiar opening switches are fuses. It is shown that a strong oxidizer (H 2 O 2 in water), especially in combination with wires of Al, increases the maximum voltage. Thermally driven opening switches are the result of attempts to achive the speed and economy of fuse opening switches but with added advantage of repetitive operation. The search for coordinate materials for this type of opening switch is in its infancy and it is difficult to predict how successful such a switch may be. Explosive opening switches offer the possibility of precise timing and permit the delay before explosion to be controlled independently of current flowing through the switch. Plasma guns, dense plasma focus and MHD switches are also considered. Diffuse discharge opening switches are attractive for repetitive operation. The plasma erosion switch operates on a very short time scale of 10 ns to 100 ns, both to regard to conduction and opening times

  20. A Specific Population of Reticulospinal Neurons Controls the Termination of Locomotion

    OpenAIRE

    Juvin, Laurent; Grätsch, Swantje; Trillaud-Doppia, Emilie; Gariépy, Jean-François; Büschges, Ansgar; Dubuc, Réjean

    2016-01-01

    Locomotion requires the proper sequencing of neural activity to start, maintain, and stop it. Recently, brainstem neurons were shown to specifically stop locomotion in mammals. However, the cellular properties of these neurons and their activity during locomotion are still unknown. Here, we took advantage of the lamprey model to characterize the activity of a cell population that we now show to be involved in stopping locomotion. We find that these neurons display a burst of spikes that coinc...

  1. Abacus switch: a new scalable multicast ATM switch

    Science.gov (United States)

    Chao, H. Jonathan; Park, Jin-Soo; Choe, Byeong-Seog

    1995-10-01

    This paper describes a new architecture for a scalable multicast ATM switch from a few tens to thousands of input ports. The switch, called Abacus switch, has a nonblocking memoryless switch fabric followed by small switch modules at the output ports; the switch has input and output buffers. Cell replication, cell routing, output contention resolution, and cell addressing are all performed distributedly in the Abacus switch so that it can be scaled up to thousnads input and output ports. A novel algorithm has been proposed to resolve output port contention while achieving input and output ports. A novel algorithm has been proposed to reolve output port contention while achieving input buffers sharing, fairness among the input ports, and multicast call splitting. The channel grouping concept is also adopted in the switch to reduce the hardware complexity and improve the switch's throughput. The Abacus switch has a regular structure and thus has the advantages of: 1) easy expansion, 2) relaxed synchronization for data and clock signals, and 3) building the switch fabric using existing CMOS technology.

  2. 49 CFR 223.17 - Identification of equipped locomotives, passenger cars and cabooses.

    Science.gov (United States)

    2010-10-01

    ... cars and cabooses. 223.17 Section 223.17 Transportation Other Regulations Relating to Transportation...-LOCOMOTIVES, PASSENGER CARS AND CABOOSES Specific Requirements § 223.17 Identification of equipped locomotives, passenger cars and cabooses. Each locomotive, passenger car and caboose that is fully equipped with glazing...

  3. Optical fiber switch

    Science.gov (United States)

    Early, James W.; Lester, Charles S.

    2002-01-01

    Optical fiber switches operated by electrical activation of at least one laser light modulator through which laser light is directed into at least one polarizer are used for the sequential transport of laser light from a single laser into a plurality of optical fibers. In one embodiment of the invention, laser light from a single excitation laser is sequentially transported to a plurality of optical fibers which in turn transport the laser light to separate individual remotely located laser fuel ignitors. The invention can be operated electro-optically with no need for any mechanical or moving parts, or, alternatively, can be operated electro-mechanically. The invention can be used to switch either pulsed or continuous wave laser light.

  4. Beyond the switch

    DEFF Research Database (Denmark)

    Aliakseyeu, Dzmitry; Meerbeek, Bernt; Mason, Jon

    2014-01-01

    The commercial introduction of connected lighting that can be integrated with sensors and other devices is opening up new possibilities in creating responsive and intelligent environments. The role of lighting in such systems goes beyond simply functional illumination. In part due to the large...... is to explore new ways of interacting with light where lighting can not only be switched on or off, but is an intelligent system embedded in the environment capable of creating a variety of effects. The connectivity between multiple systems and other ecosystems, for example when transitioning from your home...... and established lighting network, and with the advent of the LED, new types of lighting output are now possible. However, the current approach for controlling such systems is to simply replace the light switch with a somewhat more sophisticated smartphone-based remote control. The focus of this workshop...

  5. Laser activated superconducting switch

    International Nuclear Information System (INIS)

    Wolf, A.A.

    1976-01-01

    A superconducting switch or bistable device is described consisting of a superconductor in a cryogen maintaining a temperature just below the transition temperature, having a window of the proper optical frequency band for passing a laser beam which may impinge on the superconductor when desired. The frequency of the laser is equal to or greater than the optical absorption frequency of the superconducting material and is consistent with the ratio of the gap energy of the switch material to Planck's constant, to cause depairing of electrons, and thereby normalize the superconductor. Some embodiments comprise first and second superconducting metals. Other embodiments feature the two superconducting metals separated by a thin film insulator through which the superconducting electrons tunnel during superconductivity

  6. Coulomb Blockade Plasmonic Switch.

    Science.gov (United States)

    Xiang, Dao; Wu, Jian; Gordon, Reuven

    2017-04-12

    Tunnel resistance can be modulated with bias via the Coulomb blockade effect, which gives a highly nonlinear response current. Here we investigate the optical response of a metal-insulator-nanoparticle-insulator-metal structure and show switching of a plasmonic gap from insulator to conductor via Coulomb blockade. By introducing a sufficiently large charging energy in the tunnelling gap, the Coulomb blockade allows for a conductor (tunneling) to insulator (capacitor) transition. The tunnelling electrons can be delocalized over the nanocapacitor again when a high energy penalty is added with bias. We demonstrate that this has a huge impact on the plasmonic resonance of a 0.51 nm tunneling gap with ∼70% change in normalized optical loss. Because this structure has a tiny capacitance, there is potential to harness the effect for high-speed switching.

  7. Practical switching power supply design

    CERN Document Server

    Brown, Martin C

    1990-01-01

    Take the ""black magic"" out of switching power supplies with Practical Switching Power Supply Design! This is a comprehensive ""hands-on"" guide to the theory behind, and design of, PWM and resonant switching supplies. You'll find information on switching supply operation and selecting an appropriate topology for your application. There's extensive coverage of buck, boost, flyback, push-pull, half bridge, and full bridge regulator circuits. Special attention is given to semiconductors used in switching supplies. RFI/EMI reduction, grounding, testing, and safety standards are also deta

  8. Python Switch Statement

    Directory of Open Access Journals (Sweden)

    2008-06-01

    Full Text Available The Python programming language does not have a built in switch/case control structure as found in many other high level programming languages. It is thought by some that this is a deficiency in the language, and the control structure should be added. This paper demonstrates that not only is the control structure not needed, but that the methods available in Python are more expressive than built in case statements in other high level languages.

  9. Nanomechanics of flexoelectric switching

    Science.gov (United States)

    Očenášek, J.; Lu, H.; Bark, C. W.; Eom, C. B.; Alcalá, J.; Catalan, G.; Gruverman, A.

    2015-07-01

    We examine the phenomenon of flexoelectric switching of polarization in ultrathin films of barium titanate induced by a tip of an atomic force microscope (AFM). The spatial distribution of the tip-induced flexoelectricity is computationally modeled both for perpendicular mechanical load (point measurements) and for sliding load (scanning measurements), and compared with experiments. We find that (i) perpendicular load does not lead to stable ferroelectric switching in contrast to the load applied in the sliding contact load regime, due to nontrivial differences between the strain distributions in both regimes: ferroelectric switching for the perpendicular load mode is impaired by a strain gradient inversion layer immediately underneath the AFM tip; while for the sliding load regime, domain inversion is unimpaired within a greater material volume subjected to larger values of the mechanically induced electric field that includes the region behind the sliding tip; (ii) beyond a relatively small value of an applied force, increasing mechanical pressure does not increase the flexoelectric field inside the film, but results instead in a growing volume of the region subjected to such field that aids domain nucleation processes; and (iii) the flexoelectric coefficients of the films are of the order of few nC/m, which is much smaller than for bulk BaTi O3 ceramics, indicating that there is a "flexoelectric size effect" that mirrors the ferroelectric one.

  10. "Platform switching": Serendipity

    Directory of Open Access Journals (Sweden)

    N Kalavathy

    2014-01-01

    Full Text Available Implant dentistry is the latest developing field in terms of clinical techniques, research, material science and oral rehabilitation. Extensive work is being done to improve the designing of implants in order to achieve better esthetics and function. The main drawback with respect to implant restoration is achieving good osseointegration along with satisfactory stress distribution, which in turn will improve the prognosis of implant prosthesis by reducing the crestal bone loss. Many concepts have been developed with reference to surface coating of implants, surgical techniques for implant placement, immediate and delayed loading, platform switching concept, etc. This article has made an attempt to review the concept of platform switching was in fact revealed accidentally due to the nonavailability of the abutment appropriate to the size of the implant placed. A few aspect of platform switching, an upcoming idea to reduce crestal bone loss have been covered. The various methods used for locating and preparing the data were done through textbooks, Google search and related articles.

  11. Using Computational and Mechanical Models to Study Animal Locomotion

    Science.gov (United States)

    Miller, Laura A.; Goldman, Daniel I.; Hedrick, Tyson L.; Tytell, Eric D.; Wang, Z. Jane; Yen, Jeannette; Alben, Silas

    2012-01-01

    Recent advances in computational methods have made realistic large-scale simulations of animal locomotion possible. This has resulted in numerous mathematical and computational studies of animal movement through fluids and over substrates with the purpose of better understanding organisms’ performance and improving the design of vehicles moving through air and water and on land. This work has also motivated the development of improved numerical methods and modeling techniques for animal locomotion that is characterized by the interactions of fluids, substrates, and structures. Despite the large body of recent work in this area, the application of mathematical and numerical methods to improve our understanding of organisms in the context of their environment and physiology has remained relatively unexplored. Nature has evolved a wide variety of fascinating mechanisms of locomotion that exploit the properties of complex materials and fluids, but only recently are the mathematical, computational, and robotic tools available to rigorously compare the relative advantages and disadvantages of different methods of locomotion in variable environments. Similarly, advances in computational physiology have only recently allowed investigators to explore how changes at the molecular, cellular, and tissue levels might lead to changes in performance at the organismal level. In this article, we highlight recent examples of how computational, mathematical, and experimental tools can be combined to ultimately answer the questions posed in one of the grand challenges in organismal biology: “Integrating living and physical systems.” PMID:22988026

  12. Decoding bipedal locomotion from the rat sensorimotor cortex

    NARCIS (Netherlands)

    Rigosa, J.; Panarese, A.; Dominici, N.; Friedli, L.; van den Brand, R.; Carpaneto, J.; DiGiovanna, J.; Courtine, G.; Micera, S.

    2015-01-01

    Objective. Decoding forelimb movements from the firing activity of cortical neurons has been interfaced with robotic and prosthetic systems to replace lost upper limb functions in humans. Despite the potential of this approach to improve locomotion and facilitate gait rehabilitation, decoding lower

  13. Locomotion and basicranial anatomy in primates and marsupials.

    Science.gov (United States)

    Villamil, Catalina I

    2017-10-01

    There is ongoing debate in paleoanthropology about whether and how the anatomy of the cranium, and especially the cranial base, is evolving in response to locomotor and postural changes. However, the majority of studies focus on two-dimensional data, which fails to capture the complexity of cranial anatomy. This study tests whether three-dimensional cranial base anatomy is linked to locomotion or to other factors in primates (n = 473) and marsupials (n = 231). Results indicate that although there is a small effect of locomotion on cranial base anatomy in primates, this is not the case in marsupials. Instead, facial anatomy likely drives variation in cranial base anatomy in both primates and marsupials, with additional roles for body size and brain size. Although some changes to foramen magnum position and orientation are phylogenetically useful among the hominoids, they do not necessarily reflect locomotion or positional behavior. The interplay between locomotion, posture, and facial anatomy in primates requires further investigation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Energetic extremes in aquatic locomotion by coral reef fishes.

    Science.gov (United States)

    Fulton, Christopher J; Johansen, Jacob L; Steffensen, John F

    2013-01-01

    Underwater locomotion is challenging due to the high friction and resistance imposed on a body moving through water and energy lost in the wake during undulatory propulsion. While aquatic organisms have evolved streamlined shapes to overcome such resistance, underwater locomotion has long been considered a costly exercise. Recent evidence for a range of swimming vertebrates, however, has suggested that flapping paired appendages around a rigid body may be an extremely efficient means of aquatic locomotion. Using intermittent flow-through respirometry, we found exceptional energetic performance in the Bluelined wrasse Stethojulis bandanensis, which maintains tuna-like optimum cruising speeds (up to 1 metre s(-1)) while using 40% less energy than expected for their body size. Displaying an exceptional aerobic scope (22-fold above resting), streamlined rigid-body posture, and wing-like fins that generate lift-based thrust, S. bandanensis literally flies underwater to efficiently maintain high optimum swimming speeds. Extreme energetic performance may be key to the colonization of highly variable environments, such as the wave-swept habitats where S. bandanensis and other wing-finned species tend to occur. Challenging preconceived notions of how best to power aquatic locomotion, biomimicry of such lift-based fin movements could yield dramatic reductions in the power needed to propel underwater vehicles at high speed.

  15. Scaling in Theropod Dinosaurs: Femoral Bone Strength and Locomotion II

    Science.gov (United States)

    Lee, Scott

    2015-01-01

    In the second paper of this series, the effect of transverse femoral stresses due to locomotion in theropod dinosaurs of different sizes was examined for the case of an unchanging leg geometry. Students are invariably thrilled to learn about theropod dinosaurs, and this activity applies the concepts of torque and stress to the issue of theropod…

  16. Scaling in Theropod Dinosaurs: Femoral Bone Strength and Locomotion

    Science.gov (United States)

    Lee, Scott

    2015-01-01

    In our first article on scaling in theropod dinosaurs, the longitudinal stress in the leg bones due to supporting the weight of the animal was studied and found not to control the dimensions of the femur. As a continuation of our study of elasticity in dinosaur bones, we now examine the transverse stress in the femur due to locomotion and find…

  17. Energetic extremes in aquatic locomotion by coral reef fishes.

    Directory of Open Access Journals (Sweden)

    Christopher J Fulton

    Full Text Available Underwater locomotion is challenging due to the high friction and resistance imposed on a body moving through water and energy lost in the wake during undulatory propulsion. While aquatic organisms have evolved streamlined shapes to overcome such resistance, underwater locomotion has long been considered a costly exercise. Recent evidence for a range of swimming vertebrates, however, has suggested that flapping paired appendages around a rigid body may be an extremely efficient means of aquatic locomotion. Using intermittent flow-through respirometry, we found exceptional energetic performance in the Bluelined wrasse Stethojulis bandanensis, which maintains tuna-like optimum cruising speeds (up to 1 metre s(-1 while using 40% less energy than expected for their body size. Displaying an exceptional aerobic scope (22-fold above resting, streamlined rigid-body posture, and wing-like fins that generate lift-based thrust, S. bandanensis literally flies underwater to efficiently maintain high optimum swimming speeds. Extreme energetic performance may be key to the colonization of highly variable environments, such as the wave-swept habitats where S. bandanensis and other wing-finned species tend to occur. Challenging preconceived notions of how best to power aquatic locomotion, biomimicry of such lift-based fin movements could yield dramatic reductions in the power needed to propel underwater vehicles at high speed.

  18. Dynamics and locomotion of flexible foils in a frictional environment

    Science.gov (United States)

    Wang, Xiaolin; Alben, Silas

    2018-01-01

    Over the past few decades, oscillating flexible foils have been used to study the physics of organismal propulsion in different fluid environments. Here, we extend this work to a study of flexible foils in a frictional environment. When the foil is oscillated by heaving at one end but is not free to locomote, the dynamics change from periodic to non-periodic and chaotic as the heaving amplitude increases or the bending rigidity decreases. For friction coefficients lying in a certain range, the transition passes through a sequence of N-periodic and asymmetric states before reaching chaotic dynamics. Resonant peaks are damped and shifted by friction and large heaving amplitudes, leading to bistable states. When the foil is free to locomote, the horizontal motion smoothes the resonant behaviours. For moderate frictional coefficients, steady but slow locomotion is obtained. For large transverse friction and small tangential friction corresponding to wheeled snake robots, faster locomotion is obtained. Travelling wave motions arise spontaneously, and move with horizontal speeds that scale as transverse friction coefficient to the power 1/4 and input power that scales as the transverse friction coefficient to the power 5/12. These scalings are consistent with a boundary layer form of the solutions near the foil's leading edge.

  19. Energetic Extremes in Aquatic Locomotion by Coral Reef Fishes

    Science.gov (United States)

    Fulton, Christopher J.; Johansen, Jacob L.; Steffensen, John F.

    2013-01-01

    Underwater locomotion is challenging due to the high friction and resistance imposed on a body moving through water and energy lost in the wake during undulatory propulsion. While aquatic organisms have evolved streamlined shapes to overcome such resistance, underwater locomotion has long been considered a costly exercise. Recent evidence for a range of swimming vertebrates, however, has suggested that flapping paired appendages around a rigid body may be an extremely efficient means of aquatic locomotion. Using intermittent flow-through respirometry, we found exceptional energetic performance in the Bluelined wrasse Stethojulis bandanensis, which maintains tuna-like optimum cruising speeds (up to 1 metre s−1) while using 40% less energy than expected for their body size. Displaying an exceptional aerobic scope (22-fold above resting), streamlined rigid-body posture, and wing-like fins that generate lift-based thrust, S. bandanensis literally flies underwater to efficiently maintain high optimum swimming speeds. Extreme energetic performance may be key to the colonization of highly variable environments, such as the wave-swept habitats where S. bandanensis and other wing-finned species tend to occur. Challenging preconceived notions of how best to power aquatic locomotion, biomimicry of such lift-based fin movements could yield dramatic reductions in the power needed to propel underwater vehicles at high speed. PMID:23326566

  20. Application of flywheel energy storage for heavy haul locomotives

    International Nuclear Information System (INIS)

    Spiryagin, Maksym; Wolfs, Peter; Szanto, Frank; Sun, Yan Quan; Cole, Colin; Nielsen, Dwayne

    2015-01-01

    Highlights: • A novel design for heavy haul locomotive equipped with a flywheel energy storage system is proposed. • The integrated intelligent traction control system was developed. • A flywheel energy storage system has been tested through a simulation process. • The developed hybrid system was verified using an existing heavy haul railway route. • Fuel efficiency analysis confirms advantages of the hybrid design. - Abstract: At the present time, trains in heavy haul operations are typically hauled by several diesel-electric locomotives coupled in a multiple unit. This paper studies the case of a typical consist of three Co–Co diesel-electric locomotives, and considers replacing one unit with an alternative version, with the same design parameters, except that the diesel-electric plant is replaced with flywheel energy storage equipment. The intelligent traction and energy control system installed in this unit is integrated into the multiple-unit control to allow redistribution of the power between all units. In order to verify the proposed design, a three-stage investigation has been performed as described in this paper. The initial stage studies a possible configuration of the flywheel energy storage system by detailed modelling of the proposed intelligent traction and energy control system. The second stage includes the investigation and estimation of possible energy flows using a longitudinal train dynamics simulation. The final stage compares the conventional and the proposed locomotive configurations considering two parameters: fuel efficiency and emissions reduction.

  1. Physical fitness, nutritional habits and daily locomotive action of 12 ...

    African Journals Online (AJOL)

    Objective. The purpose of this study was to examine the differences in physical fitness, daily nutritional habits and locomotive behaviour among pupils with varying body mass index (BMI) in the 5th and 6th grades of primary school. Design. The sample consisted of 480 pupils (229 boys and 251 girls), who participated in ...

  2. Transmembrane channel-like (tmc) gene regulates Drosophila larval locomotion.

    Science.gov (United States)

    Guo, Yanmeng; Wang, Yuping; Zhang, Wei; Meltzer, Shan; Zanini, Damiano; Yu, Yue; Li, Jiefu; Cheng, Tong; Guo, Zhenhao; Wang, Qingxiu; Jacobs, Julie S; Sharma, Yashoda; Eberl, Daniel F; Göpfert, Martin C; Jan, Lily Yeh; Jan, Yuh Nung; Wang, Zuoren

    2016-06-28

    Drosophila larval locomotion, which entails rhythmic body contractions, is controlled by sensory feedback from proprioceptors. The molecular mechanisms mediating this feedback are little understood. By using genetic knock-in and immunostaining, we found that the Drosophila melanogaster transmembrane channel-like (tmc) gene is expressed in the larval class I and class II dendritic arborization (da) neurons and bipolar dendrite (bd) neurons, both of which are known to provide sensory feedback for larval locomotion. Larvae with knockdown or loss of tmc function displayed reduced crawling speeds, increased head cast frequencies, and enhanced backward locomotion. Expressing Drosophila TMC or mammalian TMC1 and/or TMC2 in the tmc-positive neurons rescued these mutant phenotypes. Bending of the larval body activated the tmc-positive neurons, and in tmc mutants this bending response was impaired. This implicates TMC's roles in Drosophila proprioception and the sensory control of larval locomotion. It also provides evidence for a functional conservation between Drosophila and mammalian TMCs.

  3. Neurovascular coupling and decoupling in the cortex during voluntary locomotion.

    Science.gov (United States)

    Huo, Bing-Xing; Smith, Jared B; Drew, Patrick J

    2014-08-13

    Hemodynamic signals are widely used to infer neural activity in the brain. We tested the hypothesis that hemodynamic signals faithfully report neural activity during voluntary behaviors by measuring cerebral blood volume (CBV) and neural activity in the somatosensory cortex and frontal cortex of head-fixed mice during locomotion. Locomotion induced a large and robust increase in firing rate and gamma-band (40-100 Hz) power in the local field potential in the limb representations in somatosensory cortex, and was accompanied by increases in CBV, demonstrating that hemodynamic signals are coupled with neural activity in this region. However, in the frontal cortex, CBV did not change during locomotion, but firing rate and gamma-band power both increased, indicating a decoupling of neural activity from the hemodynamic signal. These results show that hemodynamic signals are not faithful indicators of the mean neural activity in the frontal cortex during locomotion; thus, the results from fMRI and other hemodynamic imaging methodologies for studying neural processes must be interpreted with caution. Copyright © 2014 the authors 0270-6474/14/3410975-07$15.00/0.

  4. Locomotion in Stroke Subjects: Interactions between Unaffected and Affected Sides

    Science.gov (United States)

    Kloter, Evelyne; Wirz, Markus; Dietz, Volker

    2011-01-01

    The aim of this study was to evaluate the sensorimotor interactions between unaffected and affected sides of post-stroke subjects during locomotion. In healthy subjects, stimulation of the tibial nerve during the mid-stance phase is followed by electromyography responses not only in the ipsilateral tibialis anterior, but also in the proximal arm…

  5. Using Jacqueline Woodson's "Locomotion" with Middle School Readers

    Science.gov (United States)

    Napoli, Mary; Ritholz, Emily Rose

    2009-01-01

    Motivation is an essential component in developing a love of reading in middle level struggling students. For these readers, novels in verse bridge the gap to more challenging pieces of literature. In this article, Title One students explored Locomotion by Jacqueline Woodson and learned that they, too, are poets. (Contains 9 figures.)

  6. A Method for Locomotion Mode Identification Using Muscle Synergies.

    Science.gov (United States)

    Afzal, Taimoor; Iqbal, Kamran; White, Gannon; Wright, Andrew B

    2017-06-01

    Active lower limb transfemoral prostheses have enabled amputees to perform different locomotion modes such as walking, stair ascent, stair descent, ramp ascent and ramp descent. To achieve seamless mode transitions, these devices either rely on neural information from the amputee's residual limbs or sensors attached to the prosthesis to identify the intended locomotion modes or both. We present an approach for classification of locomotion modes based on the framework of muscle synergies underlying electromyography signals. Neural information at the critical instances (e.g., heel contact and toe-off) was decoded for this purpose. Non-negative matrix factorization was used to extract the muscles synergies from the muscle feature matrix. The estimation of the neural command was done using non-negative least squares. The muscle synergy approach was compared with linear discriminant analysis (LDA), support vector machine (SVM), and neural network (NN) and was tested on seven able-bodied subjects. There was no significant difference ( p > 0.05 ) in transitional and steady state classification errors during stance phase. The muscle synergy approach performed significantly better ( ) than NN and LDA during swing phase while results were similar to SVM. These results suggest that the muscle synergy approach can be used to discriminate between locomotion modes involving transitions.

  7. Tractable Quantification of Metastability for Robust Bipedal Locomotion

    Science.gov (United States)

    2015-06-01

    Mathematics GPA 4.0/4.0 2007-2011 Sabanci University, Istanbul B.S. in Mechatronics Engineering Minor in Mathematics GPA 3.88/4.0 Major GPA: 3.96/4.00...on Mechatronics (ICM), pages 997-1002, April 2011. viii Abstract Tractable Quantification of Metastability for Robust Bipedal Locomotion by Cenk Oguz

  8. Using computational and mechanical models to study animal locomotion.

    Science.gov (United States)

    Miller, Laura A; Goldman, Daniel I; Hedrick, Tyson L; Tytell, Eric D; Wang, Z Jane; Yen, Jeannette; Alben, Silas

    2012-11-01

    Recent advances in computational methods have made realistic large-scale simulations of animal locomotion possible. This has resulted in numerous mathematical and computational studies of animal movement through fluids and over substrates with the purpose of better understanding organisms' performance and improving the design of vehicles moving through air and water and on land. This work has also motivated the development of improved numerical methods and modeling techniques for animal locomotion that is characterized by the interactions of fluids, substrates, and structures. Despite the large body of recent work in this area, the application of mathematical and numerical methods to improve our understanding of organisms in the context of their environment and physiology has remained relatively unexplored. Nature has evolved a wide variety of fascinating mechanisms of locomotion that exploit the properties of complex materials and fluids, but only recently are the mathematical, computational, and robotic tools available to rigorously compare the relative advantages and disadvantages of different methods of locomotion in variable environments. Similarly, advances in computational physiology have only recently allowed investigators to explore how changes at the molecular, cellular, and tissue levels might lead to changes in performance at the organismal level. In this article, we highlight recent examples of how computational, mathematical, and experimental tools can be combined to ultimately answer the questions posed in one of the grand challenges in organismal biology: "Integrating living and physical systems."

  9. Origami-based earthworm-like locomotion robots.

    Science.gov (United States)

    Fang, Hongbin; Zhang, Yetong; Wang, K W

    2017-10-16

    Inspired by the morphology characteristics of the earthworms and the excellent deformability of origami structures, this research creates a novel earthworm-like locomotion robot through exploiting the origami techniques. In this innovation, appropriate actuation mechanisms are incorporated with origami ball structures into the earthworm-like robot 'body', and the earthworm's locomotion mechanism is mimicked to develop a gait generator as the robot 'centralized controller'. The origami ball, which is a periodic repetition of waterbomb units, could output significant bidirectional (axial and radial) deformations in an antagonistic way similar to the earthworm's body segment. Such bidirectional deformability can be strategically programmed by designing the number of constituent units. Experiments also indicate that the origami ball possesses two outstanding mechanical properties that are beneficial to robot development: one is the structural multistability in the axil direction that could contribute to the robot control implementation; and the other is the structural compliance in the radial direction that would increase the robot robustness and applicability. To validate the origami-based innovation, this research designs and constructs three robot segments based on different axial actuators: DC-motor, shape-memory-alloy springs, and pneumatic balloon. Performance evaluations reveal their merits and limitations, and to prove the concept, the DC-motor actuation is selected for building a six-segment robot prototype. Learning from earthworms' fundamental locomotion mechanism-retrograde peristalsis wave, seven gaits are automatically generated; controlled by which, the robot could achieve effective locomotion with qualitatively different modes and a wide range of average speeds. The outcomes of this research could lead to the development of origami locomotion robots with low fabrication costs, high customizability, light weight, good scalability, and excellent re-configurability.

  10. A locomotion intent prediction system based on multi-sensor fusion.

    Science.gov (United States)

    Chen, Baojun; Zheng, Enhao; Wang, Qining

    2014-07-10

    Locomotion intent prediction is essential for the control of powered lower-limb prostheses to realize smooth locomotion transitions. In this research, we develop a multi-sensor fusion based locomotion intent prediction system, which can recognize current locomotion mode and detect locomotion transitions in advance. Seven able-bodied subjects were recruited for this research. Signals from two foot pressure insoles and three inertial measurement units (one on the thigh, one on the shank and the other on the foot) are measured. A two-level recognition strategy is used for the recognition with linear discriminate classifier. Six kinds of locomotion modes and ten kinds of locomotion transitions are tested in this study. Recognition accuracy during steady locomotion periods (i.e., no locomotion transitions) is 99.71% ± 0.05% for seven able-bodied subjects. During locomotion transition periods, all the transitions are correctly detected and most of them can be detected before transiting to new locomotion modes. No significant deterioration in recognition performance is observed in the following five hours after the system is trained, and small number of experiment trials are required to train reliable classifiers.

  11. Energy-based control for a biologically inspired hexapod robot with rolling locomotion

    Directory of Open Access Journals (Sweden)

    Takuma Nemoto

    2015-04-01

    Full Text Available This paper presents an approach to control rolling locomotion on the level ground with a biologically inspired hexapod robot. For controlling rolling locomotion, a controller which can compensate energy loss with rolling locomotion of the hexapod robot is designed based on its dynamic model. The dynamic model describes the rolling locomotion which is limited to planar one by an assumption that the hexapod robot does not fall down while rolling and influences due to collision and contact with the ground, and it is applied for computing the mechanical energy of the hexapod robot and a plant for a numerical simulation. The numerical simulation of the rolling locomotion on the level ground verifies the effectiveness of the proposed controller. The simulation results show that the hexapod robot can perform the rolling locomotion with the proposed controller. In conclusion, it is shown that the proposed control approach is effective in achieving the rolling locomotion on the level ground.

  12. ANALYSIS OF THE OPERATIONAL CHARACTERISTICS OF DIESEL-ELECTRIC LOCOMOTIVES

    Directory of Open Access Journals (Sweden)

    L. V. Ursulyak

    2014-12-01

    Full Text Available Purpose. To compare the operational characteristics of freight diesel-electric locomotives ER20CF and 2М62м, which are operated with Lithuanian Railways. Important problems on traction calculations are considered in this article. In this article the critical tasks of traction calculations are solved. It is the main computational tool in the rational functioning, planning and development of railways: determination of the estimated weight of the rolling stock, the diagrams construction of specific resultant forces of a train, the permitted speed definition of the train on the slopes, curves of train traffic construction on the section. Methodology. Using the rules and methods of traction calculations the analysis of the basic operational characteristics of the modernized freight diesel-electric locomotive 2М62m and freight passenger dual locomotive 2ER20CF was held. The maximum weight of the train set, the track structure on a high-speed ascent through the use of kinetic energy (with traction and without traction, technical speed, acceleration force and the value of the smallest radius curve are selected as controlled parameters. During the calculations it was considered that the trains were formed of a fully loaded four-axle gondola cars, model 112-119 (feature-606 with axle load of 23.5 t; the motion was carried out on the continuous welded rail track; the front of the train set is a dual locomotive 2ER20CF or two locomotive 2М62м. Longitudinal profile of the road on the route Vilnus–KlF was analyzed for the choice of theoretical rise. Inspection concerning the possibility of overcoming the high-speed rise was performed with an analytical method, based on the use of the kinetic energy accumulated by the overcoming of «light» elements of the profile. Findings. In the calculations, the maximum weight of the train set taking into account theoretical rise was analyzed. The inspection of the theoretical weight of the train set on a reliable

  13. Safe LPV Controller Switching

    DEFF Research Database (Denmark)

    Trangbæk, K

    2011-01-01

    Before switching to a new controller it is crucial to assure that the new closed loop will be stable. In this paper it is demonstrated how stability can be checked with limited measurement data available from the current closed loop. The paper extends an existing method to linear parameter varying...... plants and controllers. Rather than relying on frequency domain methods as done in the LTI case, it is shown how to use standard LPV system identification methods. It is furthermore shown how to include model uncertainty to robustify the results. By appropriate filtering, it is only necessary to evaluate...

  14. Safe LPV Controller Switching

    DEFF Research Database (Denmark)

    Trangbæk, K

    2010-01-01

    Before switching to a new controller it is crucial to assure that the new closed loop will be stable. In this paper it is demonstrated how stability can be checked with limited measurement data available from the current closed loop. The paper extends an existing method to linear parameter varying...... plants and controllers. Rather than relying on frequency domain methods as done in the LTI case, it is shown how to use standard LPV system identification methods. By identifying a filtered closed-loop operator rather than directly identifying the plant, more reliable results are obtained....

  15. Locomotion of Stramonita haemastoma (Linnaeus (Gastropoda, Muricidae on a mixed shore of rocks and sand

    Directory of Open Access Journals (Sweden)

    Marcos G. Papp

    2001-03-01

    Full Text Available Mixed shores of rocks and sand are appropriate systems for the study of limitations that the isolation of rocks may impose for gastropods that typically inhabit rocky shores. We marked 52 Stramonita haemastoma (Linnaeus, 1767 snails on a mixed shore and found that 34 of them moved between rocks one to four times during 15 surveys in a period of 72 days. In the experiments, the snails moved on rock by continuous, direct, ditaxic, alternate undulations of the foot sole but on submerged sand they used slower arrhythmic discontinuous contractions of the foot sole. They switched between modes of locomotion in response to the type and topography of the substrate and possibly to water dynamics. In nature, snails moved between rocks forming aggregations where they oviposited. This may have masked other causes of movement, such as availability of prey. Most snails burrowed into the sand when the rocks became exposed during low tides. Further experiments are needed to explicitly address the possible causes of movements among rocks and burial.

  16. Mechanics of a rapid running insect: two-, four- and six-legged locomotion.

    Science.gov (United States)

    Full, R J; Tu, M S

    1991-03-01

    To examine the effects of variation in body form on the mechanics of terrestrial locomotion, we used a miniature force platform to measure the ground reaction forces of the smallest and, relative to its mass, one of the fastest invertebrates ever studied, the American cockroach Periplaneta americana (mass = 0.83 g). From 0.44-1.0 ms-1, P. americana used an alternating tripod stepping pattern. Fluctuations in gravitational potential energy and horizontal kinetic energy of the center of mass were nearly in phase, characteristic of a running or bouncing gait. Aerial phases were observed as vertical ground reaction force approached zero at speeds above 1 ms-1. At the highest speeds (1.0-1.5 ms-1 or 50 body lengths per second), P. americana switched to quadrupedal and bipedal running. Stride frequency approached the wing beat frequencies used during flight (27 Hz). High speeds were attained by increasing stride length, whereas stride frequency showed little increase with speed. The mechanical power used to accelerate the center of mass increased curvilinearly with speed. The mass-specific mechanical energy used to move the center of mass a given distance was similar to that measured for animals five orders of magnitude larger in mass, but was only one-hundredth of the metabolic cost.

  17. Neuromorphic atomic switch networks.

    Directory of Open Access Journals (Sweden)

    Audrius V Avizienis

    Full Text Available Efforts to emulate the formidable information processing capabilities of the brain through neuromorphic engineering have been bolstered by recent progress in the fabrication of nonlinear, nanoscale circuit elements that exhibit synapse-like operational characteristics. However, conventional fabrication techniques are unable to efficiently generate structures with the highly complex interconnectivity found in biological neuronal networks. Here we demonstrate the physical realization of a self-assembled neuromorphic device which implements basic concepts of systems neuroscience through a hardware-based platform comprised of over a billion interconnected atomic-switch inorganic synapses embedded in a complex network of silver nanowires. Observations of network activation and passive harmonic generation demonstrate a collective response to input stimulus in agreement with recent theoretical predictions. Further, emergent behaviors unique to the complex network of atomic switches and akin to brain function are observed, namely spatially distributed memory, recurrent dynamics and the activation of feedforward subnetworks. These devices display the functional characteristics required for implementing unconventional, biologically and neurally inspired computational methodologies in a synthetic experimental system.

  18. Modeling of rf MEMS switches

    Science.gov (United States)

    Robertson, Barbara; Ho, Fat D.; Hudson, Tracy D.

    2001-10-01

    The microelectromechanical system (MEMS) switch offers many benefits in radio frequency (RF) applications. These benefits include low insertion loss, high quality factor (Q), low power, RF isolation, and low cost. The ability to manufacture mechanical switches on a chip with electronics can lead to higher functionality, such as single-chip arrays, and smart switches. The MEMS switch is also used as a building block in devices such as phase shifters, filters, and switchable antenna elements. The MEMS designer needs models of these basic elements in order to incorporate them into their applications. The objective of this effort is to develop lumped element models for MEMS RF switches, which are incorporated into a CAD software. Tanner Research Inc.'s Electronic Design Automation (EDA) software is being used to develop a suite of mixed-signal RF switch models. The suite will include switches made from cantilever beams and fixed-fixed beams. The switches may be actuated by electrostatic, piezoelectric or electromagnetic forces. The effort presented in this paper concentrates on switches actuated by electrostatic forces. The lumped element models use a current-force electrical-mechanical analogy. Finite element modeling and device testing will be used to verify the Tanner models. The effects of materials, geometries, temperature, fringing fields, and mounting geometries are considered.

  19. Software Switching for Data Acquisition

    CERN Multimedia

    CERN. Geneva; Malone, David

    2016-01-01

    In this talk we discuss the feasibility of replacing telecom-class routers with a topology of commodity servers acting as software switches in data acquisition. We extend the popular software switch, Open vSwitch, with a dedicated, throughput-oriented buffering mechanism. We compare the performance under heavy many-to-one congestion to typical Ethernet switches and evaluate the scalability when building larger topologies, exploiting the integration with software-defined networking technologies. Please note that David Malone will speak on behalf of Grzegorz Jereczek.

  20. Recent developments in switching theory

    CERN Document Server

    Mukhopadhyay, Amar

    2013-01-01

    Electrical Science Series: Recent Developments in Switching Theory covers the progress in the study of the switching theory. The book discusses the simplified proof of Post's theorem on completeness of logic primitives; the role of feedback in combinational switching circuits; and the systematic procedure for the design of Lupanov decoding networks. The text also describes the classical results on counting theorems and their application to the classification of switching functions under different notions of equivalence, including linear and affine equivalences. The development of abstract har

  1. Investigation of Timing to Switch Control Mode in Powered Knee Prostheses during Task Transitions.

    Directory of Open Access Journals (Sweden)

    Fan Zhang

    Full Text Available Current powered prosthetic legs require switching control modes according to the task the user is performing (e.g. level-ground walking, stair climbing, walking on slopes, etc.. To allow prosthesis users safely and seamlessly transition between tasks, it is critical to determine when to switch the prosthesis control mode during task transitions. Our previous study defined critical timings for different types of task transitions in ambulation; however, it is unknown whether it is the unique timing that allows safe and seamless transitions. The goals of this study were to (1 systematically investigate the effects of mode switch timing on the prosthesis user's performance in task transitions, and (2 identify appropriate timing to switch the prosthesis control mode so that the users can seamlessly transition between different locomotion tasks. Five able-bodied (AB and two transfemoral (TF amputee subjects were tested as they wore a powered knee prosthesis. The prosthesis control mode was switched manually at various times while the subjects performed different types of task transitions. The subjects' task transition performances were evaluated by their walking balance and success in performing seamless task transitions. The results demonstrated that there existed a time window within which switching the prosthesis control mode neither interrupted the subjects' task transitions nor disturbed their walking balance. Therefore, the results suggested the control mode switching of a lower limb prosthesis can be triggered within an appropriate time window instead of a specific timing or an individual phase. In addition, a generalized criterion to determine the appropriate mode switch timing was proposed. The outcomes of this study could provide important guidance for future designs of neurally controlled powered knee prostheses that are safe and reliable to use.

  2. Spinal corollary discharge modulates motion sensing during vertebrate locomotion.

    Science.gov (United States)

    Chagnaud, Boris P; Banchi, Roberto; Simmers, John; Straka, Hans

    2015-09-04

    During active movements, neural replicas of the underlying motor commands may assist in adapting motion-detecting sensory systems to an animal's own behaviour. The transmission of such motor efference copies to the mechanosensory periphery offers a potential predictive substrate for diminishing sensory responsiveness to self-motion during vertebrate locomotion. Here, using semi-isolated in vitro preparations of larval Xenopus, we demonstrate that shared efferent neural pathways to hair cells of vestibular endorgans and lateral line neuromasts express cyclic impulse bursts during swimming that are directly driven by spinal locomotor circuitry. Despite common efferent innervation and discharge patterns, afferent signal encoding at the two mechanosensory peripheries is influenced differentially by efference copy signals, reflecting the different organization of body/water motion-detecting processes in the vestibular and lateral line systems. The resultant overall gain reduction in sensory signal encoding in both cases, which likely prevents overstimulation, constitutes an adjustment to increased stimulus magnitudes during locomotion.

  3. Biorobotics: using robots to emulate and investigate agile locomotion.

    Science.gov (United States)

    Ijspeert, Auke J

    2014-10-10

    The graceful and agile movements of animals are difficult to analyze and emulate because locomotion is the result of a complex interplay of many components: the central and peripheral nervous systems, the musculoskeletal system, and the environment. The goals of biorobotics are to take inspiration from biological principles to design robots that match the agility of animals, and to use robots as scientific tools to investigate animal adaptive behavior. Used as physical models, biorobots contribute to hypothesis testing in fields such as hydrodynamics, biomechanics, neuroscience, and prosthetics. Their use may contribute to the design of prosthetic devices that more closely take human locomotion principles into account. Copyright © 2014, American Association for the Advancement of Science.

  4. The coal-fired gas turbine locomotive - A new look

    Science.gov (United States)

    Liddle, S. G.; Bonzo, B. B.; Purohit, G. P.

    1983-01-01

    Advances in turbomachine technology and novel methods of coal combustion may have made possible the development of a competitive coal fired gas turbine locomotive engine. Of the combustor, thermodynamic cycle, and turbine combinations presently assessed, an external combustion closed cycle regenerative gas turbine with a fluidized bed coal combustor is judged to be the best suited for locomotive requirements. Some merit is also discerned in external combustion open cycle regenerative systems and internal combustion open cycle regenerative gas turbine systems employing a coal gasifier. The choice of an open or closed cycle depends on the selection of a working fluid and the relative advantages of loop pressurization, with air being the most attractive closed cycle working fluid on the basis of cost.

  5. The Perceived Naturalness of Virtual Walking Speeds during WIP Locomotion

    DEFF Research Database (Denmark)

    Nilsson, Niels Chr.; Serafin, Stefania; Nordahl, Rolf

    2016-01-01

    It is well established that individuals tend to underestimate visually presented walking speeds when relying on treadmills for virtual walking. However, prior to the present studies this perceptual distortion had not been observed in relation to Walking-in-Place (WIP) locomotion, and a number...... of the factors contributing to the perceptual distortion have yet to be identified. In this paper we present a summary of seven of our studies investigating what factors that influence self-motion perception during virtual walking and two meta-analyses of the findings of the seven studies. The studies relate...... to how gait cycle characteristics, visual display properties, and methodological differences affect speed underestimation during treadmill and WIP locomotion. The studies suggested the following: A significant main effect was found for step frequency; both display and geometric field of view were...

  6. Hybrid control and motion planning of dynamical legged locomotion

    CERN Document Server

    2012-01-01

    "This book provides a comprehensive presentation of issues and challenges faced by researchers and practicing engineers in motion planning and hybrid control of dynamical legged locomotion. The major features range from offline and online motion planning algorithms to generate desired feasible periodic walking and running motions and tow-level control schemes, including within-stride feedback laws, continuous time update laws and event-based update laws, to asymptotically stabilize the generated desired periodic orbits. This book describes the current state of the art and future directions across all domains of dynamical legged locomotion so that readers can extend proposed motion planning algorithms and control methodologies to other types of planar and 3D legged robots".

  7. Modern power electronics for locomotives; Moderne Leistungselektronik im Lokomotiveinsatz

    Energy Technology Data Exchange (ETDEWEB)

    Bakran, M.M.; Eckel, H.G.; Nagel, A. [Siemens AG, Nuernberg (Germany)

    2007-07-01

    Locomotives represent a challenging application for high-power electronics in terms of power, voltage-level and operating conditions. The driving forces are the development of semiconductor devices, the corresponding circuit topologies and the resulting drive properties. The transition from GTO to IGBT allowed building more compact converters with a more flexible power rating. This for example made the integration of the auxiliary converter an effective solution. The development of 6.5kV IGBTs made possible easier operation on the 3kV-dc line, however, still with optimized and different solutions for multisystem locomotives. The actual development of semiconductor technology still suggests a further increase in power density. (orig.)

  8. Full-scale locomotive dynamic crash testing and correlations : locomotive consist colliding with steel coil truck at grade crossing (test 3).

    Science.gov (United States)

    2011-09-01

    This report presents the test results and finite element correlations of a full-scale dynamic collision between a locomotive and a highway truck loaded with two heavy steel coils. The locomotive consist was moving at 58 miles per hour before it struc...

  9. Theoretical and experimental study on a compliant flipper-leg during terrestrial locomotion.

    Science.gov (United States)

    Fang, Tao; Zhou, Youcheng; Li, Shikun; Xu, Min; Liang, Haiyi; Li, Weihua; Zhang, Shiwu

    2016-08-17

    An amphibious robot with straight compliant flipper-legs can conquer various amphibious environments. The robot can rotate its flipper-legs and utilize their large deflection to walk on rough terrain, and it can oscillate the straight flipper-legs to propel itself underwater. This paper focuses on the dynamics of the compliant straight flipper-legs during terrestrial locomotion by modeling its deformation dynamically with large deflection theory and simulating it to investigate the parameters of locomotion such as trajectory, velocity, and propulsion. To validate the theoretical model of dynamic locomotion, a single-leg experimental platform is used to explore the flipper-legs in motion with various structural and kinematic parameters. Furthermore, a robotic platform mounting with four compliant flipper-legs is also developed and used to experiment with locomotion. The trajectories of the rotating axle of the compliant flipper-leg during locomotion were approximately coincidental in simulation and in experiments. The speed of locomotion and cost of transport during locomotion were explored and analyzed. The performance of different types of compliant flipper-legs during locomotion shows that varying the degrees of stiffness will have a significant effect on their locomotion. The dynamic model and analysis of the compliant flipper-leg for terrestrial locomotion facilitates the ability of amphibious robots to conquer complex environments.

  10. Phalangeal joints kinematics in ostrich (Struthio camelus) locomotion on sand

    Science.gov (United States)

    Han, Dianlei; Wan, Haijin; Li, Xiujuan; Luo, Gang; Xue, Shuliang; Ma, Songsong; Yang, Mingming; Li, Jianqiao

    2018-01-01

    In ostriches, the toes are the only body parts that contact loose sand surfaces. Thus, toe interphalangeal joint motions may play vital biomechanical roles. However, there is little research on ostrich phalangeal joint movements while walking or running on sand. The results from the three-dimensional motion track analysis system Simi Motion show that gait pattern has no significant effect on the key indicators (angles at touch-down, mid-stance, lift-off and range of motion) of the toe joint angles. The motion of the toe phalanges when walking and running on sand is basically the same. The ground medium is the key factor that changes the toe postures adopted by ostriches during the stance phase in slow to fast locomotion. The 3rd toe and the 4th toe are connected by the interphalangeal ligament, and the motions of the MTP3 and MTP4 joints are highly synchronized on a loose sand substrate. The 3rd toe and 4th toe are coupled to maintain static balance in slow locomotion and dynamic balance in fast locomotion. In addition, the gait pattern has a marked effect on the range of forward displacement of the toenail (YTN). The ostrich toenail plays an important role in preventing slip and provides traction at push-off in a sandy environment. The metatarsophalangeal joint plays an important role in energy saving during fast locomotion on loose sand substrates. Simulation reveals that the particle velocity field, particle force field and sand particle disturbance in the running gait are denser than those in the walking gait. PMID:29489844

  11. Dynamic Locomotion and Whole-Body Control for Compliant Humanoids

    OpenAIRE

    Hopkins, Michael Anthony

    2015-01-01

    With the ability to navigate natural and man-made environments and utilize standard human tools, humanoid robots have the potential to transform emergency response and disaster relief applications by serving as first responders in hazardous scenarios. Such applications will require major advances in humanoid control, enabling robots to traverse difficult, cluttered terrain with both speed and stability. To advance the state of the art, this dissertation presents a complete dynamic locomotion ...

  12. Brief anesthesia, but not voluntary locomotion, significantly alters cortical temperature

    Science.gov (United States)

    Shirey, Michael J.; Kudlik, D'Anne E.; Huo, Bing-Xing; Greene, Stephanie E.; Drew, Patrick J.

    2015-01-01

    Changes in brain temperature can alter electrical properties of neurons and cause changes in behavior. However, it is not well understood how behaviors, like locomotion, or experimental manipulations, like anesthesia, alter brain temperature. We implanted thermocouples in sensorimotor cortex of mice to understand how cortical temperature was affected by locomotion, as well as by brief and prolonged anesthesia. Voluntary locomotion induced small (∼0.1°C) but reliable increases in cortical temperature that could be described using a linear convolution model. In contrast, brief (90-s) exposure to isoflurane anesthesia depressed cortical temperature by ∼2°C, which lasted for up to 30 min after the cessation of anesthesia. Cortical temperature decreases were not accompanied by a concomitant decrease in the γ-band local field potential power, multiunit firing rate, or locomotion behavior, which all returned to baseline within a few minutes after the cessation of anesthesia. In anesthetized animals where core body temperature was kept constant, cortical temperature was still >1°C lower than in the awake animal. Thermocouples implanted in the subcortex showed similar temperature changes under anesthesia, suggesting these responses occur throughout the brain. Two-photon microscopy of individual blood vessel dynamics following brief isoflurane exposure revealed a large increase in vessel diameter that ceased before the brain temperature significantly decreased, indicating cerebral heat loss was not due to increased cerebral blood vessel dilation. These data should be considered in experimental designs recording in anesthetized preparations, computational models relating temperature and neural activity, and awake-behaving methods that require brief anesthesia before experimental procedures. PMID:25972579

  13. The role of vortices in animal locomotion in fluids

    Directory of Open Access Journals (Sweden)

    Dvořák R.

    2014-12-01

    Full Text Available The aim of this paper is to show the significance of vortices in animal locomotion in fluids on two deliberately chosen examples. The first example concerns lift generation by bird and insect wings, the second example briefly mentiones swimming and walking on water. In all the examples, the vortices generated by the moving animal impart the necessary momentum to the surrounding fluid, the reaction to which is the force moving or lifting the animal.

  14. Performance analysis of jump-gliding locomotion for miniature robotics.

    Science.gov (United States)

    Vidyasagar, A; Zufferey, Jean-Christohphe; Floreano, Dario; Kovač, M

    2015-03-26

    Recent work suggests that jumping locomotion in combination with a gliding phase can be used as an effective mobility principle in robotics. Compared to pure jumping without a gliding phase, the potential benefits of hybrid jump-gliding locomotion includes the ability to extend the distance travelled and reduce the potentially damaging impact forces upon landing. This publication evaluates the performance of jump-gliding locomotion and provides models for the analysis of the relevant dynamics of flight. It also defines a jump-gliding envelope that encompasses the range that can be achieved with jump-gliding robots and that can be used to evaluate the performance and improvement potential of jump-gliding robots. We present first a planar dynamic model and then a simplified closed form model, which allow for quantification of the distance travelled and the impact energy on landing. In order to validate the prediction of these models, we validate the model with experiments using a novel jump-gliding robot, named the 'EPFL jump-glider'. It has a mass of 16.5 g and is able to perform jumps from elevated positions, perform steered gliding flight, land safely and traverse on the ground by repetitive jumping. The experiments indicate that the developed jump-gliding model fits very well with the measured flight data using the EPFL jump-glider, confirming the benefits of jump-gliding locomotion to mobile robotics. The jump-glide envelope considerations indicate that the EPFL jump-glider, when traversing from a 2 m height, reaches 74.3% of optimal jump-gliding distance compared to pure jumping without a gliding phase which only reaches 33.4% of the optimal jump-gliding distance. Methods of further improving flight performance based on the models and inspiration from biological systems are presented providing mechanical design pathways to future jump-gliding robot designs.

  15. Locomotion Efficiency Optimization of Biologically Inspired Snake Robots

    OpenAIRE

    Eleni Kelasidi; Mansoureh Jesmani; Kristin Y. Pettersen; Jan Tommy Gravdahl

    2018-01-01

    Snake robots constitute bio-inspired solutions that have been studied due to their ability to move in challenging environments where other types of robots, such as wheeled or legged robots, usually fail. In this paper, we consider both land-based and swimming snake robots. One of the principal concerns of the bio-inspired snake robots is to increase the motion efficiency in terms of the forward speed by improving the locomotion methods. Furthermore, energy efficiency becomes a crucial challen...

  16. Phenotypic switching in bacteria

    Science.gov (United States)

    Merrin, Jack

    Living matter is a non-equilibrium system in which many components work in parallel to perpetuate themselves through a fluctuating environment. Physiological states or functionalities revealed by a particular environment are called phenotypes. Transitions between phenotypes may occur either spontaneously or via interaction with the environment. Even in the same environment, genetically identical bacteria can exhibit different phenotypes of a continuous or discrete nature. In this thesis, we pursued three lines of investigation into discrete phenotypic heterogeneity in bacterial populations: the quantitative characterization of the so-called bacterial persistence, a theoretical model of phenotypic switching based on those measurements, and the design of artificial genetic networks which implement this model. Persistence is the phenotype of a subpopulation of bacteria with a reduced sensitivity to antibiotics. We developed a microfluidic apparatus, which allowed us to monitor the growth rates of individual cells while applying repeated cycles of antibiotic treatments. We were able to identify distinct phenotypes (normal and persistent) and characterize the stochastic transitions between them. We also found that phenotypic heterogeneity was present prior to any environmental cue such as antibiotic exposure. Motivated by the experiments with persisters, we formulated a theoretical model describing the dynamic behavior of several discrete phenotypes in a periodically varying environment. This theoretical framework allowed us to quantitatively predict the fitness of dynamic populations and to compare survival strategies according to environmental time-symmetries. These calculations suggested that persistence is a strategy used by bacterial populations to adapt to fluctuating environments. Knowledge of the phenotypic transition rates for persistence may provide statistical information about the typical environments of bacteria. We also describe a design of artificial

  17. Central Pattern Generator for Locomotion: Anatomical, Physiological and Pathophysiological Considerations

    Directory of Open Access Journals (Sweden)

    Pierre A. Guertin

    2013-02-01

    Full Text Available This article provides a perspective on major innovations over the past century in research on the spinal cord and, specifically, on specialized spinal circuits involved in the control of rhythmic locomotor pattern generation and modulation. Pioneers such as Charles Sherrington and Thomas Graham Brown have conducted experiments in the early twentieth century that changed our views of the neural control of locomotion. Their seminal work supported subsequently by several decades of evidence has led to the conclusion that walking, flying and swimming are largely controlled by a network of spinal neurons generally referred to as the central pattern generator (CPG for locomotion. It has been subsequently demonstrated across all vertebrate species examined, from lampreys to humans, that this CPG is capable, under some conditions, to self-produce, even in absence of descending or peripheral inputs, basic rhythmic and coordinated locomotor movements. Recent evidence suggests, in turn, that plasticity changes of some CPG elements may contribute to the development of specific pathophysiological conditions associated with impaired locomotion or spontaneous locomotor-like movements. This article constitutes a comprehensive review summarizing key findings on the CPG as well as on its potential role in Restless Leg Syndrome (RLS, Periodic Leg Movement (PLM, and Alternating Leg Muscle Activation (ALMA. Special attention will be paid to the role of the CPG in a recently identified, and uniquely different neurological disorder, called the Uner Tan Syndrome.

  18. Enhanced Caenorhabditis elegans locomotion in a structured microfluidic environment.

    Directory of Open Access Journals (Sweden)

    Sungsu Park

    Full Text Available BACKGROUND: Behavioral studies of Caenorhabditis elegans traditionally are done on the smooth surface of agar plates, but the natural habitat of C. elegans and other nematodes is the soil, a complex and structured environment. In order to investigate how worms move in such environments, we have developed a technique to study C. elegans locomotion in microstructures fabricated from agar. METHODOLOGY/PRINCIPAL FINDINGS: When placed in open, liquid-filled, microfluidic chambers containing a square array of posts, we discovered that worms are capable of a novel mode of locomotion, which combines the fast gait of swimming with the more efficient movements of crawling. When the wavelength of the worms matched the periodicity of the post array, the microstructure directed the swimming and increased the speed of C. elegans ten-fold. We found that mutants defective in mechanosensation (mec-4, mec-10 or mutants with abnormal waveforms (unc-29 did not perform this enhanced locomotion and moved much more slowly than wild-type worms in the microstructure. CONCLUSION/SIGNIFICANCE: These results show that the microstructure can be used as a behavioral screen for mechanosensory and uncoordinated mutants. It is likely that worms use mechanosensation in the movement and navigation through heterogeneous environments.

  19. Chimpanzee ankle and foot joint kinematics: Arboreal versus terrestrial locomotion.

    Science.gov (United States)

    Holowka, Nicholas B; O'Neill, Matthew C; Thompson, Nathan E; Demes, Brigitte

    2017-09-01

    Many aspects of chimpanzee ankle and midfoot joint morphology are believed to reflect adaptations for arboreal locomotion. However, terrestrial travel also constitutes a significant component of chimpanzee locomotion, complicating functional interpretations of chimpanzee and fossil hominin foot morphology. Here we tested hypotheses of foot motion and, in keeping with general assumptions, we predicted that chimpanzees would use greater ankle and midfoot joint ranges of motion during travel on arboreal supports than on the ground. We used a high-speed motion capture system to measure three-dimensional kinematics of the ankle and midfoot joints in two male chimpanzees during three locomotor modes: terrestrial quadrupedalism on a flat runway, arboreal quadrupedalism on a horizontally oriented tree trunk, and climbing on a vertically oriented tree trunk. Chimpanzees used relatively high ankle joint dorsiflexion angles during all three locomotor modes, although dorsiflexion was greatest in arboreal modes. They used higher subtalar joint coronal plane ranges of motion during terrestrial and arboreal quadrupedalism than during climbing, due in part to their use of high eversion angles in the former. Finally, they used high midfoot inversion angles during arboreal locomotor modes, but used similar midfoot sagittal plane kinematics across all locomotor modes. The results indicate that chimpanzees use large ranges of motion at their various ankle and midfoot joints during both terrestrial and arboreal locomotion. Therefore, we argue that chimpanzee foot anatomy enables a versatile locomotor repertoire, and urge caution when using foot joint morphology to reconstruct arboreal behavior in fossil hominins. © 2017 Wiley Periodicals, Inc.

  20. Control method for biped locomotion robots based on ZMP information

    Energy Technology Data Exchange (ETDEWEB)

    Kume, Etsuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1994-01-01

    The Human Acts Simulation Program (HASP) started as a ten year program of Computing and Information Systems Center (CISC) at Japan Atomic Energy Research Institute (JAERI) in 1987. A mechanical design study of biped locomotion robots for patrol and inspection in nuclear facilities is being performed as an item of the research scope. One of the goals of our research is to design a biped locomotion robot for practical use in nuclear facilities. So far, we have been studying for several dynamic walking patterns. In conventional control methods for biped locomotion robots, the program control is used based on preset walking patterns, so it dose not have the robustness such as a dynamic change of walking pattern. Therefore, a real-time control method based on dynamic information of the robot states is necessary for the high performance of walking. In this study a new control method based on Zero Moment Point (ZMP) information is proposed as one of real-time control methods. The proposed method is discussed and validated based on the numerical simulation. (author).

  1. Hybrid switch for resonant power converters

    Science.gov (United States)

    Lai, Jih-Sheng; Yu, Wensong

    2014-09-09

    A hybrid switch comprising two semiconductor switches connected in parallel but having different voltage drop characteristics as a function of current facilitates attainment of zero voltage switching and reduces conduction losses to complement reduction of switching losses achieved through zero voltage switching in power converters such as high-current inverters.

  2. A Radical Switch

    Directory of Open Access Journals (Sweden)

    Alexander Rappaport

    2017-09-01

    Full Text Available Architecture is the most vulnerable part of culture, almost doomed to destruction of its fundamentals, while the rise of its intellectual and creative level is badly needed. However, neither the resort to postmarxist French philosophy nor bringing the results of development of science and technology into architecture, neither computerization nor peculiarities of parametricism and deconstructivism are helpful. It can be stated that in the beginning of the third millennium architecture and architectural education are in stalemate. The way out is in a “radical” switch from comprehension of object space to the time and to the processes of thinking, designing and historical change in professional mentality. The interests must be focused not on the object, but on the process enabling the use of return reflexive strokes as well.

  3. Battery switch for downhole tools

    Science.gov (United States)

    Boling, Brian E.

    2010-02-23

    An electrical circuit for a downhole tool may include a battery, a load electrically connected to the battery, and at least one switch electrically connected in series with the battery and to the load. The at least one switch may be configured to close when a tool temperature exceeds a selected temperature.

  4. Improved switch-resistor packaging

    Science.gov (United States)

    Redmerski, R. E.

    1980-01-01

    Packaging approach makes resistors more accessible and easily identified with specific switches. Failures are repaired more quickly because of improved accessibility. Typical board includes one resistor that acts as circuit breaker, and others are positioned so that their values can be easily measured when switch is operated. Approach saves weight by using less wire and saves valuable panel space.

  5. Task Switching: A PDP Model

    Science.gov (United States)

    Gilbert, Sam J.; Shallice, Tim

    2002-01-01

    When subjects switch between a pair of stimulus-response tasks, reaction time is slower on trial N if a different task was performed on trial N--1. We present a parallel distributed processing (PDP) model that simulates this effect when subjects switch between word reading and color naming in response to Stroop stimuli. Reaction time on "switch…

  6. A CMOS Switched Transconductor Mixer

    NARCIS (Netherlands)

    Klumperink, Eric A.M.; Louwsma, S.M.; Wienk, Gerhardus J.M.; Nauta, Bram

    A new CMOS active mixer topology can operate at low supply voltages by the use of switches exclusively connected to the supply voltages. Such switches require less voltage headroom and avoid gate-oxide reliability problems. Mixing is achieved by exploiting two transconductors with cross-coupled

  7. Lack of adaptation during prolonged split-belt locomotion in the intact and spinal cat.

    Science.gov (United States)

    Kuczynski, Victoria; Telonio, Alessandro; Thibaudier, Yann; Hurteau, Marie-France; Dambreville, Charline; Desrochers, Etienne; Doelman, Adam; Ross, Declan; Frigon, Alain

    2017-09-01

    During split-belt locomotion in humans where one leg steps faster than the other, the symmetry of step lengths and double support periods of the slow and fast legs is gradually restored. When returning to tied-belt locomotion, there is an after-effect, with a reversal in the asymmetry observed in the early split-belt period, indicating that the new pattern was stored within the central nervous system. In this study, we investigated if intact and spinal-transected cats show a similar pattern of adaptation to split-belt locomotion by measuring kinematic variables and electromyography before, during and after 10 min of split-belt locomotion. The results show that cats do not adapt to prolonged split-belt locomotion. Our results suggest an important physiological difference in how cats and humans respond to prolonged asymmetric locomotion. In humans, gait adapts to prolonged walking on a split-belt treadmill, where one leg steps faster than the other, by gradually restoring the symmetry of interlimb kinematic variables, such as double support periods and step lengths, and by reducing muscle activity (EMG, electromyography). The adaptation is also characterized by reversing the asymmetry of interlimb variables observed during the early split-belt period when returning to tied-belt locomotion, termed an after-effect. To determine if cats adapt to prolonged split-belt locomotion and to assess if spinal locomotor circuits participate in the adaptation, we measured interlimb variables and EMG in intact and spinal-transected cats before, during and after 10 min of split-belt locomotion. In spinal cats, only the hindlimbs performed stepping with the forelimbs stationary. In intact and spinal cats, step lengths and double support periods were, on average, symmetric, during tied-belt locomotion. They became asymmetric during split-belt locomotion and remained asymmetric throughout the split-belt period. Upon returning to tied-belt locomotion, symmetry was immediately restored

  8. Pectoral fin locomotion in batoid fishes: undulation versus oscillation.

    Science.gov (United States)

    Rosenberger, L J

    2001-01-01

    This study explores the dichotomy between undulatory (passing multiple waves down the fin or body) and oscillatory (flapping) locomotion by comparing the kinematics of pectoral fin locomotion in eight species of batoids (Dasyatis americana, D. sabina, D. say, D. violacea, Gymnura micrura, Raja eglanteria, Rhinobatos lentiginosus and Rhinoptera bonasus) that differ in their swimming behavior, phylogenetic position and lifestyle. The goals of this study are to describe and compare the pectoral fin locomotor behavior of the eight batoid species, to clarify how fin movements change with swimming speed for each species and to analyze critically the undulation/oscillation continuum proposed by Breder using batoids as an example. Kinematic data were recorded for each species over a range of swimming velocities (1-3 disc lengths s(-1)). The eight species in this study vary greatly in their swimming modes. Rhinobatos lentiginosus uses a combination of axial-based and pectoral-fin-based undulation to move forward through the water, with primary thrust generated by the tail. The pectoral fins are activated in short undulatory bursts for increasing swimming speed and for maneuvering. Raja eglanteria uses a combination of pectoral and pelvic locomotion, although only pectoral locomotion is analyzed here. The other six species use pectoral locomotion exclusively to propel themselves through the water. Dasyatis sabina and D. say have the most undulatory fins with an average of 1.3 waves per fin length, whereas Rhinoptera bonasus has the most oscillatory fin behavior with 0.4 waves per fin length. The remaining species range between these two extremes in the degree of undulation present on their fins. There is an apparent trade-off between fin-beat frequency and amplitude. Rhinoptera bonasus has the lowest frequency and the highest fin amplitude, whereas Rhinobatos lentiginosus has the highest frequency and the lowest amplitude among the eight species examined. The kinematic

  9. Amorphous metal based nanoelectromechanical switch

    KAUST Repository

    Mayet, Abdulilah M.

    2013-04-01

    Nanoelectromechanical (NEM) switch is an interesting ultra-low power option which can operate in the harsh environment and can be a complementary element in complex digital circuitry. Although significant advancement is happening in this field, report on ultra-low voltage (pull-in) switch which offers high switching speed and area efficiency is yet to be made. One key challenge to achieve such characteristics is to fabricate nano-scale switches with amorphous metal so the shape and dimensional integrity are maintained to achieve the desired performance. Therefore, we report a tungsten alloy based amorphous metal with fabrication process development of laterally actuated dual gated NEM switches with 100 nm width and 200 nm air-gap to result in <5 volts of actuation voltage (Vpull-in). © 2013 IEEE.

  10. Association of Mode of Locomotion and Independence in Locomotion With Long-Term Outcomes After Spinal Cord Injury

    Science.gov (United States)

    Krause, James; Carter, Rickey E; Brotherton, Sandra

    2009-01-01

    Background/Objective: To explore the association of mode of locomotion (ambulation vs wheelchair use) and independence in locomotion (independent vs require assistance) with health, participation, and subjective well-being (SWB) after spinal cord injury (SCI). Research Design: Secondary analysis was conducted on survey data collected from 2 rehabilitation hospitals in the Midwest and a specialty hospital in the southeastern United States. The 1,493 participants were a minimum of 18 years of age and had traumatic SCI of at least 1 year duration at enrollment. Main Outcome Measures: Three sets of outcome measures were used: SWB, participation, and health. SWB was measured by 8 scales and a measure of depressive symptoms, participation by 3 items, health by general health ratings, days in poor health, hospitalizations, and treatments. Results: Small but significant associations were observed between independence in locomotion and every outcome. Ambulation was associated with greater participation but a mixed pattern of favorable and unfavorable health and SWB outcomes. Supplemental analyses were conducted on those who ambulated but who were dependent on others to do so (n = 117), because this group reported poor outcomes in several areas. Individuals who were independent in wheelchair use reported substantially better outcomes than nonwheelchair users and those dependent on others in wheelchair use. Conclusions: Although ambulation is often a recovery goal, individuals with SCI who ambulate do not uniformly report better outcomes than wheelchair users, and those who depend on others for assistance with ambulation may experience a unique set of problems. PMID:19810625

  11. Switching Phenomena in a System with No Switches

    Science.gov (United States)

    Preis, Tobias; Stanley, H. Eugene

    2010-02-01

    It is widely believed that switching phenomena require switches, but this is actually not true. For an intriguing variety of switching phenomena in nature, the underlying complex system abruptly changes from one state to another in a highly discontinuous fashion. For example, financial market fluctuations are characterized by many abrupt switchings creating increasing trends ("bubble formation") and decreasing trends ("financial collapse"). Such switching occurs on time scales ranging from macroscopic bubbles persisting for hundreds of days to microscopic bubbles persisting only for a few seconds. We analyze a database containing 13,991,275 German DAX Future transactions recorded with a time resolution of 10 msec. For comparison, a database providing 2,592,531 of all S&P500 daily closing prices is used. We ask whether these ubiquitous switching phenomena have quantifiable features independent of the time horizon studied. We find striking scale-free behavior of the volatility after each switching occurs. We interpret our findings as being consistent with time-dependent collective behavior of financial market participants. We test the possible universality of our result by performing a parallel analysis of fluctuations in transaction volume and time intervals between trades. We show that these financial market switching processes have properties similar to those of phase transitions. We suggest that the well-known catastrophic bubbles that occur on large time scales—such as the most recent financial crisis—are no outliers but single dramatic representatives caused by the switching between upward and downward trends on time scales varying over nine orders of magnitude from very large (≈102 days) down to very small (≈10 ms).

  12. The Relationship between Locomotive Syndrome and Depression in Community-Dwelling Elderly People

    OpenAIRE

    Misa Nakamura; Hiroshi Hashizume; Sachiko Nomura; Ryohei Kono; Hirotoshi Utsunomiya

    2017-01-01

    Locomotive syndrome (LS) is a concept that refers to the condition of people requiring healthcare services because of problems associated with locomotion. Depression is a major psychiatric disease among the elderly, in addition to dementia. The purpose of this study was to determine the association between LS and depression. The study participants were 224 healthy elderly volunteers living in a rural area in Japan. LS was defined as scores ≥ 16 on the 25-question Geriatric Locomotive Function...

  13. Closing the Loop: Integrating Body, Muscle and Environment with Locomotion Central Pattern Generators

    Science.gov (United States)

    2013-06-30

    between the neural circuitry, body, and fluid environment for swimming locomotion , where the lamprey serves as a model system1,2,3,4,5,6,7,8. Our...REPORT Final Report: Closing the Loop: Integrating Body, Muscle and Environment with Locomotion Central Pattern Generators 14. ABSTRACT 16. SECURITY...CLASSIFICATION OF: The role of sensory feedback is a central question in understanding vertebrate locomotion . Sensory feedback related to movement of

  14. Model Reduction of Switched Systems Based on Switching Generalized Gramians

    DEFF Research Database (Denmark)

    Shaker, Hamid Reza; Wisniewski, Rafal

    2012-01-01

    In this paper, a general method for model order reduction of discrete-time switched linear systems is presented. The proposed technique uses switching generalized gramians. It is shown that several classical reduction methods can be developed into the generalized gramian framework for the model...... reduction of linear systems and for the reduction of switched systems. Discrete-time balanced reduction within a specified frequency interval is taken as an example within this framework. To avoid numerical instability and to increase the numerical efficiency, a generalized gramian-based Petrov...

  15. INFLUENCE OF ROLLING STOCK VIBROACOUSTICAL PARAMETERS ON THE CHOICE OF RATIONAL VALUES OF LOCOMOTIVE RUNNING GEAR

    Directory of Open Access Journals (Sweden)

    Yu. V. Zelenko

    2016-06-01

    Full Text Available Purpose.The success of the traffic on the railways of Ukraine depends on the number and the operational fleet of electric locomotives. Today, the locomotive depot exploit physically and morally outdated locomotives that have low reliability. Modernization of electric locomotives is not economically justified. The aim of this study is to improve the safety of the traction rolling stock by the frequency analysis of dynamical systems, which allows conducting the calculation of the natural (of resonant frequencies of the design and related forms of vibrations.Methodology.The study was conducted by methods of analytical mechanics and mathematical modeling of operating loads of freight locomotive when driving at different speeds on the straight and curved track sections. The theoretical value of the work is the technique of choice of constructive schemes and rational parameters of perspective electric locomotive taking into account the electric inertia ratios and stiffness coefficients of Lagrange second-order equations.Findings. The problems of theoretical research and the development of a mathematical model of the spatial electric vibrations are solved. The theoretical studies of the effect of inertia ratios and stiffness coefficients on the dynamic values and the parameter values of electric locomotive undercarriages are presented.Originality.The set of developed regulations and obtained results is a practical solution to selecting rational parameters of bogies of the freight mainline locomotive for railways of Ukraine. A concept of choice of constructive scheme and rational parameters of perspective locomotive is formulated. It is developed the method of calculation of spatial electric locomotive oscillations to determine its dynamic performance. The software complex for processing the data of experimental studies of dynamic parameters of electric locomotive and comparing the results of the theoretical calculations with the data of full

  16. On designing geometric motion planners to solve regulating and trajectory tracking problems for robotic locomotion systems

    Energy Technology Data Exchange (ETDEWEB)

    Asnafi, Alireza [Hydro-Aeronautical Research Center, Shiraz University, Shiraz, 71348-13668 (Iran, Islamic Republic of); Mahzoon, Mojtaba, E-mail: asnafi@shirazu.ac.ir, E-mail: arasnafi@yahoo.com, E-mail: mahzoon@shirazu.ac.ir [Department of Mechanical Engineering, School of Engineering, Shiraz University, Shiraz, 71348-13668 (Iran, Islamic Republic of)

    2011-09-15

    Based on a geometric fiber bundle structure, a generalized method to solve both regulation and trajectory tracking problems for locomotion systems is presented. The method is especially applied to two case studies of robotic locomotion systems; a three link articulated fish-like robot as a prototype of locomotion systems with symmetry, and the snakeboard as a prototype of mixed locomotion systems. Our results show that although these motion planners have an open loop structure, due to their generalities, they can steer case studies with negligible errors for almost any complicated path.

  17. Acquiring Efficient Locomotion in a Simulated Quadruped through Evolving Random and Predefined Neural Networks

    DEFF Research Database (Denmark)

    Veenstra, Frank; Struck, Alexander; Krauledat, Matthias

    2015-01-01

    The acquisition and optimization of dynamically stable locomotion is important to engender fast and energy efficient locomotion in animals. Conventional optimization strategies tend to have difficulties in acquiring dynamically stable gaits in legged robots. In this paper, an evolving neural...... network (ENN) was implemented with the aim to optimize the locomotive behavior of a four-legged simulated robot. In the initial generation, individuals had neural networks (NNs) that were either predefined or randomly initialized. Additional investigations show that the efficiency of applying additional...... optimize a locomotive strategy for a simulated quadruped....

  18. DETERMINANT OF DOWNWARD AUDITOR SWITCHING

    Directory of Open Access Journals (Sweden)

    Totok Budisantoso

    2017-12-01

    Full Text Available Abstract: Determinant of Downward Auditor Switching. This study examines the factors that influence downward auditor switching in five ASEAN countries. Fixed effect logistic regression was used as analytical method. This study found that opinion shopping occurred in ASEAN, especially in distress companies. Companies with complex businesses will retain the Big Four auditors to reduce complexity and audit costs. Audit and public committees serve as guardians of auditor quality. On the other hand, shareholders failed to maintain audit quality. It indicates that there is entrenchment effect in auditor switching.

  19. Sexuality of Disabled Athletes Depending on the Form of Locomotion

    Directory of Open Access Journals (Sweden)

    Plinta Ryszard

    2015-12-01

    Full Text Available The main purpose of this study was to determine sexuality of disabled athletes depending on the form of locomotion. The study included 170 disabled athletes, aged between 18 and 45. The entire population was divided into 3 research groups depending on the form of locomotion: moving on wheelchairs (n=52, on crutches (n=29 and unaided (n=89. The research tool was a questionnaire voluntarily and anonymously completed by the respondents of the research groups. The questionnaire was composed of a general part concerning the socio-demographic conditions, medical history, health problems, a part dedicated to physical disability as well as the Polish version of the International Index of Erectile Function (IIEF and the Female Sexual Function Index (FSFI evaluating sexual life. STATISTICA 10.0 for Windows was used in the statistical analysis. Subjects moving on crutches were significantly older than ones moving on wheelchairs and unaided (34.41 ±11.00 vs. 30.49 ±10.44 and 27.99 ±10.51 years, respectively (p=0.018. Clinically significant erectile dysfunctions were most often diagnosed in athletes moving on wheelchairs (70.27%, followed by athletes moving on crutches and moving unaided (60% and 35.42%, respectively; p=0.048. Clinical sexual dysfunctions were diagnosed on a similar level among all female athletes. It was concluded that the form of locomotion may determine sexuality of disabled men. Males on wheelchair revealed the worst sexual functioning. Female athletes moving on wheelchairs, on crutches and moving unaided were comparable in the aspect of their sexual life.

  20. Benefit of "Push-pull" Locomotion for Planetary Rover Mobility

    Science.gov (United States)

    Creager, Colin M.; Moreland, Scott Jared; Skonieczny, K.; Johnson, K.; Asnani, V.; Gilligan, R.

    2011-01-01

    As NASAs exploration missions on planetary terrains become more aggressive, a focus on alternative modes of locomotion for rovers is necessary. In addition to climbing steep slopes, the terrain in these extreme environments is often unknown and can be extremely hard to traverse, increasing the likelihood of a vehicle or robot becoming damaged or immobilized. The conventional driving mode in which all wheels are either driven or free-rolling is very efficient on flat hard ground, but does not always provide enough traction to propel the vehicle through soft or steep terrain. This paper presents an alternative mode of travel and investigates the fundamental differences between these locomotion modes. The methods of push-pull locomotion discussed can be used with articulated wheeled vehicles and are identified as walking or inchinginch-worming. In both cases, the braked non-rolling wheels provide increased thrust. An in-depth study of how soil reacts under a rolling wheel vs. a braked wheel was performed by visually observing the motion of particles beneath the surface. This novel technique consists of driving or dragging a wheel in a soil bin against a transparent wall while high resolution, high-rate photographs are taken. Optical flow software was then used to determine shearing patterns in the soil. Different failure modes were observed for the rolling and braked wheel cases. A quantitative comparison of inching vs. conventional driving was also performed on a full-scale vehicle through a series of drawbar pull tests in the Lunar terrain strength simulant, GRC-1. The effect of tire stiffness was also compared; typically compliant tires provide better traction when driving in soft soil, however its been observed that rigid wheels may provide better thrust when non-rolling. Initial tests indicate up to a possible 40 increase in pull force capability at high slip when inching vs. rolling.

  1. Lightweight Multifunctional Planetary Probe for Extreme Environment Exploration and Locomotion

    Science.gov (United States)

    Bayandor, Javid (Principal Investigator); Schroeder, Kevin; Samareh, Jamshid

    2017-01-01

    The demand to explore new worlds requires the development of advanced technologies that enable landed science on uncertain terrains or in hard to reach locations. As a result, contemporary Entry, Descent, Landing, (EDL) and additional locomotion (EDLL) profiles are becoming increasingly more complex, with the introduction of lifting/guided entries, hazard avoidance on descent, and a plethora of landing techniques including airbags and the skycrane maneuver. The inclusion of each of these subsystems into a mission profile is associated with a substantial mass penalty. This report explores the new all-in-one entry vehicle concept, TANDEM, a new combined EDLL concept, and compares it to the current state of the art EDL systems. The explored system is lightweight and collapsible and provides the capacity for lifting/guided entry, guided descent, hazard avoidance, omnidirectional impact protection and surface locomotion without the aid of any additional subsystems. This Phase I study explored: 1. The capabilities and feasibility of the TANDEM concept as an EDLL vehicle. 2. Extensive impact analysis to ensure mission success in unfavorable landing conditions, and safe landing in Tessera regions. 3. Development of a detailed design for a conceptual mission to Venus. As a result of our work it was shown that: 1. TANDEM provides additional benefits over the Adaptive, Deployable Entry Placement Technology (ADEPT) including guided descent and surface locomotion, while reducing the mass by 38% compared to the ADEPT-VITaL mission. 2. Demonstrated that the design of tensegrity structures, and TANDEM specifically, grows linearly with an increase in velocity, which was previously unknown. 3. Investigation of surface impact revealed a promising results that suggest a properly configured TANDEM vehicle can safely land and preform science in the Tessera regions, which was previously labeled by the Decadal Survey as, largely inaccessible despite its high scientific interest. This work

  2. Partly shared spinal cord networks for locomotion and scratching.

    Science.gov (United States)

    Berkowitz, Ari; Hao, Zhao-Zhe

    2011-12-01

    Animals produce a variety of behaviors using a limited number of muscles and motor neurons. Rhythmic behaviors are often generated in basic form by networks of neurons within the central nervous system, or central pattern generators (CPGs). It is known from several invertebrates that different rhythmic behaviors involving the same muscles and motor neurons can be generated by a single CPG, multiple separate CPGs, or partly overlapping CPGs. Much less is known about how vertebrates generate multiple, rhythmic behaviors involving the same muscles. The spinal cord of limbed vertebrates contains CPGs for locomotion and multiple forms of scratching. We investigated the extent of sharing of CPGs for hind limb locomotion and for scratching. We used the spinal cord of adult red-eared turtles. Animals were immobilized to remove movement-related sensory feedback and were spinally transected to remove input from the brain. We took two approaches. First, we monitored individual spinal cord interneurons (i.e., neurons that are in between sensory neurons and motor neurons) during generation of each kind of rhythmic output of motor neurons (i.e., each motor pattern). Many spinal cord interneurons were rhythmically activated during the motor patterns for forward swimming and all three forms of scratching. Some of these scratch/swim interneurons had physiological and morphological properties consistent with their playing a role in the generation of motor patterns for all of these rhythmic behaviors. Other spinal cord interneurons, however, were rhythmically activated during scratching motor patterns but inhibited during swimming motor patterns. Thus, locomotion and scratching may be generated by partly shared spinal cord CPGs. Second, we delivered swim-evoking and scratch-evoking stimuli simultaneously and monitored the resulting motor patterns. Simultaneous stimulation could cause interactions of scratch inputs with subthreshold swim inputs to produce normal swimming, acceleration

  3. Biodiesel fuel costs and environmental issues when powering railway locomotives

    Energy Technology Data Exchange (ETDEWEB)

    Mirza, Abdul; Ziemer, Norbert; Tatara, Robert; Moraga, Reinaldo; Mirman, Clifford; Vohra, Promod

    2010-09-15

    Issues for adopting biodiesel fuel, instead of petrodiesel, to power railroad locomotives are engine performance and emissions, fuel infrastructure, and fuel cost. These are evaluated for B2 through B100 blends. Biodiesel's solvent action on fuel systems is addressed. With biodiesel, hydrocarbon, carbon monoxide, and particulate emissions are unchanged or reduced. Nitrogen oxides are elevated but it is believed that engine alterations can minimize these emissions. A Transportation Model, using data from a major railway, has demonstrated that refueling depots can be fully supplied with biodiesel at a pricing premium of 1% to 26%, depending on blend and geographical location.

  4. Human-robot interaction strategies for walker-assisted locomotion

    CERN Document Server

    Cifuentes, Carlos A

    2016-01-01

    This book presents the development of a new multimodal human-robot interface for testing and validating control strategies applied to robotic walkers for assisting human mobility and gait rehabilitation. The aim is to achieve a closer interaction between the robotic device and the individual, empowering the rehabilitation potential of such devices in clinical applications. A new multimodal human-robot interface for testing and validating control strategies applied to robotic walkers for assisting human mobility and gait rehabilitation is presented. Trends and opportunities for future advances in the field of assistive locomotion via the development of hybrid solutions based on the combination of smart walkers and biomechatronic exoskeletons are also discussed. .

  5. Designing presence for real locomotion in immersive virtual environments

    DEFF Research Database (Denmark)

    Turchet, Luca

    2015-01-01

    This paper describes a framework for designing systems for real locomotion in virtual environments (VEs) in order to achieve an intense sense of presence. The main outcome of the present research is a list of design features that the virtual reality technology should have in order to achieve...... that allows VE designers to evaluate the maturity of their systems and to pinpoint directions for future developments. A survey analysis was performed using the proposed framework, which involved three case studies to determine how many features of the proposed framework were present and their status...

  6. Energy Efficiency of Robot Locomotion Increases Proportional to Weight

    DEFF Research Database (Denmark)

    Larsen, Jørgen Christian; Støy, Kasper

    2011-01-01

    The task of producing steady, stable and energy efficient locomotion in legged robots with the ability to walk in un- known terrain have for many years been a big challenge in robotics. This work is focusing on how different robots build from the modular robotic system, LocoKit by Larsen et. la [3......], performs compared to animals, and also on the similari- ties between robots an animals. This work shows, that there in robots exist the same connection between cost of trans- port and the weight of the robots as is true for animals....

  7. Energy Efficiency of Robot Locomotion Increases Proportional to Weight

    DEFF Research Database (Denmark)

    Larsen, J. C.; Stoy, K.

    2011-01-01

    The task of producing steady, stable and energy efficient locomotion in legged robots with the ability to walk in unknown terrain have for many years been a big challenge in robotics. This work is focusing on how different robots build from the modular robotic system, LocoKit by Larsen et al. [1......], performs compared to animals, and also on the similarities between robots an animals. This work shows, that there in robots exist the same connection between cost of transport and the weight of the robots as is true for animals. (C) Selection and peer-review under responsibility of FET11 conference...

  8. Improvement of fuel injection system of locomotive diesel engine.

    Science.gov (United States)

    Li, Minghai; Cui, Hongjiang; Wang, Juan; Guan, Ying

    2009-01-01

    The traditional locomotive diesels are usually designed for the performance of rated condition and much fuel will be consumed. A new plunger piston matching parts of fuel injection pump and injector nozzle matching parts were designed. The experimental results of fuel injection pump test and diesel engine show that the fuel consumption rate can be decreased a lot in the most of the working conditions. The forced lubrication is adopted for the new injector nozzle matching parts, which can reduce failure rate and increase service life. The design has been patented by Chinese State Patent Office.

  9. Biomechanical Analysis of Treadmill Locomotion on the International Space Station

    Science.gov (United States)

    De Witt, J. K.; Fincke, R. S.; Guilliams, M. E.; Ploutz-Snyder, L. L.

    2011-01-01

    Treadmill locomotion exercise is an important aspect of ISS exercise countermeasures. It is widely believed that an optimized treadmill exercise protocol could offer benefits to cardiovascular and bone health. If training heart rate is high enough, treadmill exercise is expected to lead to improvements in aerobic fitness. If impact or bone loading forces are high enough, treadmill exercise may be expected to contribute to improved bone outcomes. Ground-based research suggests that joint loads increase with increased running speed. However, it is unknown if increases in locomotion speed results in similar increases in joint loads in microgravity. Although data exist regarding the biomechanics of running and walking in microgravity, a majority were collected during parabolic flight or during investigations utilizing a microgravity analog. The Second Generation Treadmill (T2) has been in use on the International Space Station (ISS) and records the ground reaction forces (GRF) produced by crewmembers during exercise. Biomechanical analyses will aid in understanding potential differences in typical gait motion and allow for modeling of the human body to determine joint and muscle forces during exercise. By understanding these mechanisms, more appropriate exercise prescriptions can be developed that address deficiencies. The objective of this evaluation is to collect biomechanical data from crewmembers during treadmill exercise prior to and during flight. The goal is to determine if locomotive biomechanics differ between normal and microgravity environments and to determine how combinations of subject load and speed influence joint loading during in-flight treadmill exercise. Further, the data will be used to characterize any differences in specific bone and muscle loading during locomotion in these two gravitational conditions. This project maps to the HRP Integrated Research Plan risks including Risk of Bone Fracture (Gap B15), Risk of Early Onset Osteoporosis Due to

  10. Solid state bistable power switch

    Science.gov (United States)

    Bartko, J.; Shulman, H.

    1970-01-01

    Tin and copper provide high current and switching time capabilities for high-current resettable fuses. They show the best performance for trip current and degree of reliability, and have low coefficients of thermal expansion.

  11. Electron collisions in gas switches

    International Nuclear Information System (INIS)

    Christophorou, L.G.

    1989-01-01

    Many technologies rely on the conduction/insulation properties of gaseous matter for their successful operation. Many others (e.g., pulsed power technologies) rely on the rapid change (switching or modulation) of the properties of gaseous matter from an insulator to a conductor and vice versa. Studies of electron collision processes in gases aided the development of pulsed power gas switches, and in this paper we shall briefly illustrate the kind of knowledge on electron collision processes which is needed to optimize the performance of such switching devices. To this end, we shall refer to three types of gas switches: spark gap closing, self-sustained diffuse discharge closing, and externally-sustained diffuse discharge opening. 24 refs., 15 figs., 2 tabs

  12. Wide Bandgap Extrinsic Photoconductive Switches

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, James S. [State Univ. of New York (SUNY), Plattsburgh, NY (United States); Univ. of California, Davis, CA (United States)

    2012-01-20

    Photoconductive semiconductor switches (PCSS) have been investigated since the late 1970s. Some devices have been developed that withstand tens of kilovolts and others that switch hundreds of amperes. However, no single device has been developed that can reliably withstand both high voltage and switch high current. Yet, photoconductive switches still hold the promise of reliable high voltage and high current operation with subnanosecond risetimes. Particularly since good quality, bulk, single crystal, wide bandgap semiconductor materials have recently become available. In this chapter we will review the basic operation of PCSS devices, status of PCSS devices and properties of the wide bandgap semiconductors 4H-SiC, 6H-SiC and 2H-GaN.

  13. A Piezoelectric Cryogenic Heat Switch

    Science.gov (United States)

    Jahromi, Amir E.; Sullivan, Dan F.

    2014-01-01

    We have measured the thermal conductance of a mechanical heat switch actuated by a piezoelectric positioner, the PZHS (PieZo electric Heat Switch), at cryogenic temperatures. The thermal conductance of the PZHS was measured between 4 K and 10 K, and on/off conductance ratios greater than 100 were achieved when the positioner applied its maximum force of 8 N. We discuss the advantages of using this system in cryogenic applications, and estimate the ultimate performance of an optimized PZHS.

  14. Chromatic interocular-switch rivalry

    Science.gov (United States)

    Christiansen, Jens H.; D'Antona, Anthony D.; Shevell, Steven K.

    2017-01-01

    Interocular-switch rivalry (also known as stimulus rivalry) is a kind of binocular rivalry in which two rivalrous images are swapped between the eyes several times a second. The result is stable periods of one image and then the other, with stable intervals that span many eye swaps (Logothetis, Leopold, & Sheinberg, 1996). Previous work used this close kin of binocular rivalry with rivalrous forms. Experiments here test whether chromatic interocular-switch rivalry, in which the swapped stimuli differ in only chromaticity, results in slow alternation between two colors. Swapping equiluminant rivalrous chromaticities at 3.75 Hz resulted in slow perceptual color alternation, with one or the other color often continuously visible for two seconds or longer (during which there were 15+ eye swaps). A well-known theory for sustained percepts from interocular-switch rivalry with form is inhibitory competition between binocular neurons driven by monocular neurons with matched orientation tuning in each eye; such binocular neurons would produce a stable response when a given orientation is swapped between the eyes. A similar model can account for the percepts here from chromatic interocular-switch rivalry and is underpinned by the neurophysiological finding that color-preferring binocular neurons are driven by monocular neurons from each eye with well-matched chromatic selectivity (Peirce, Solomon, Forte, & Lennie, 2008). In contrast to chromatic interocular-switch rivalry, luminance interocular-switch rivalry with swapped stimuli that differ in only luminance did not result in slowly alternating percepts of different brightnesses. PMID:28510624

  15. Full-scale locomotive dynamic collision testing and correlations : offset collisions between a locomotive and a covered hopper car (test 4).

    Science.gov (United States)

    2011-09-01

    This report presents the test results and finite element correlations of a full-scale dynamic collision test with rail vehicles as part of the Federal Railroad Administrations research program on improved crashworthiness of locomotive structures. ...

  16. Fast muscle function in the European eel (Anguilla anguilla, L.) : during aquatic and terrestrial locomotion

    NARCIS (Netherlands)

    Ellerby, D.J.; Spierts, I.L.Y.; Altringham, J.D.

    2001-01-01

    Eels are capable of locomotion both in water and on land using undulations of the body axis. Axial undulations are powered by the lateral musculature. Differences in kinematics and the underlying patterns of fast muscle activation are apparent between locomotion in these two environments. The change

  17. 49 CFR 230.20 - Alteration and repair report for steam locomotive boilers.

    Science.gov (United States)

    2010-10-01

    ... boilers. 230.20 Section 230.20 Transportation Other Regulations Relating to Transportation (Continued... boilers. (a) Alterations. When an alteration is made to a steam locomotive boiler, the steam locomotive... maintained for the life of the boiler. (See appendix B of this part.) (b) Welded and riveted repairs to...

  18. Compressed stability analysis of the coupler and buffer system of heavy-haul locomotives

    Science.gov (United States)

    Zhang, Zhichao; Li, Gu; Chu, Gaofeng; Zu, Honglin; Kennedy, David

    2015-06-01

    This paper develops a locomotive dynamic model to study the coupler compressed stability and locomotive running safety under severe longitudinal compressive forces, taking into account a new model of the flattened pin coupler and buffer system employed by heavy-haul locomotives. In this new model, the arc surface contact friction element is built up for the first time to simulate the compressed contact friction process between the arc surfaces of the coupler tail and the following plate. An improved nonlinear mathematical model of buffers and a coupler rotation angle stop element are also included. After validating the presented locomotive dynamic model by comparing its calculated results with test data, simulations are carried out to analyse the influences of the coupler-tail arc surface and locomotive secondary suspension parameters on the coupler compressed stability and locomotive running safety. Results indicate that the friction coefficient and the arc radius of the coupler-tail arc surfaces have a remarkable influence, and that the locomotive secondary lateral stop and lateral stiffness also have a significant effect. Optimising these parameters could significantly improve the coupler compressed stability and locomotive running safety. Finally, a real example of Chinese heavy-haul trains is shown to confirm the importance of the coupler-tail contact friction action.

  19. 49 CFR 210.29 - Operation standards (moving locomotives and rail cars).

    Science.gov (United States)

    2010-10-01

    ... cars). 210.29 Section 210.29 Transportation Other Regulations Relating to Transportation (Continued... REGULATIONS Inspection and Testing § 210.29 Operation standards (moving locomotives and rail cars). The operation standards for the noise emission levels of moving locomotives, rail cars, or consists of...

  20. Design and analysis of an optimal hopper for use in resonance-based locomotion

    NARCIS (Netherlands)

    Wanders, Ivor; Folkertsma, Gerrit Adriaan; Stramigioli, Stefano

    Quadrupedal running is an efficient form of locomotion found in nature, which serves as an inspiration for robotics. We believe that a resonance-based approach is the path towards energy-efficient legged locomotion and running robots. The first step in working towards this goal is creating an

  1. Differential gating of thalamo-cortical signals by reticular nucleus of thalamus during locomotion

    Science.gov (United States)

    Marlinski, Vladimir; Sirota, Mikhail G.; Beloozerova, Irina N.

    2012-01-01

    SUMMARY The thalamic reticular nucleus (RE) provides inhibition to the dorsal thalamus, and forms a crucial interface between thalamo-cortical and cortico-thalamic signals. Whereas there has been significant interest in the role of the RE in organizing thalamo-cortical signaling, information on the activity of the RE in the awake animal is scant. Here we investigated the activity of neurons within the ‘motor’ compartment of the RE in the awake, unrestrained cat during simple locomotion on a flat surface and complex locomotion along a horizontal ladder that required visual control of stepping. The activity of 88% of neurons in this region was modulated during locomotion. Neurons with receptive fields on the shoulder were located dorsally in the nucleus and had regular discharges; during locomotion they had relatively low activity and modest magnitudes of stride-related modulation, and their group activity was distributed over the stride. In contrast, neurons with receptive fields on the wrist/paw were located more ventrally, often discharged sleep-type bursts during locomotion, were very active and profoundly modulated, and their group activity was concentrated in the swing and end of stance. 75% of RE neurons had different activity during the two locomotion tasks. We conclude that during locomotion the RE differentially gates thalamo-cortical signals transmitted during different phases of the stride, in relation to different parts of the limb, and the type of locomotion task. PMID:23136421

  2. DEVELOPMENT OF LOCOMOTION IN THE RAT - THE SIGNIFICANCE OF EARLY MOVEMENTS

    NARCIS (Netherlands)

    WESTERGA, J; GRAMSBERGEN, A

    The development of the nervous system is determined by an interaction between genetic and epigenetic factors. We investigated the possible role of proprioceptive afferent input in the development of locomotion in the rat. Kinematic analysis of locomotion in normal rats reveals a marked transition

  3. 49 CFR 1242.22 - Shop buildings-locomotives (account XX-19-24).

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 9 2010-10-01 2010-10-01 false Shop buildings-locomotives (account XX-19-24). 1242.22 Section 1242.22 Transportation Other Regulations Relating to Transportation (Continued) SURFACE... Structures § 1242.22 Shop buildings—locomotives (account XX-19-24). Separate common expenses according to...

  4. Magnetic-fluid-based smart centrifugal switch

    CERN Document Server

    Bhatt, R P

    2002-01-01

    A new type of centrifugal switch, which we call 'smart centrifugal switch' is designed and developed utilizing the novel properties of magnetic fluid. No mechanical movement is involved in the sensing and switching operations of this centrifugal switch and both these operations are achieved in a smart way. The performance of the switch is studied. This switch has several important advantages over conventional centrifugal switches like smart and non-contact type operation, sparkless and hence explosion proof working and inertia-less simple structure.

  5. A Reconfigurable Omnidirectional Soft Robot Based on Caterpillar Locomotion.

    Science.gov (United States)

    Zou, Jun; Lin, Yangqiao; Ji, Chen; Yang, Huayong

    2018-04-01

    A pneumatically powered, reconfigurable omnidirectional soft robot based on caterpillar locomotion is described. The robot is composed of nine modules arranged as a three by three matrix and the length of this matrix is 154 mm. The robot propagates a traveling wave inspired by caterpillar locomotion, and it has all three degrees of freedom on a plane (X, Y, and rotation). The speed of the robot is about 18.5 m/h (two body lengths per minute) and it can rotate at a speed of 1.63°/s. The modules have neodymium-iron-boron (NdFeB) magnets embedded and can be easily replaced or combined into other configurations. Two different configurations are presented to demonstrate the possibilities of the modular structure: (1) by removing some modules, the omnidirectional robot can be reassembled into a form that can crawl in a pipe and (2) two omnidirectional robots can crawl close to each other and be assembled automatically into a bigger omnidirectional robot. Omnidirectional motion is important for soft robots to explore unstructured environments. The modular structure gives the soft robot the ability to cope with the challenges of different environments and tasks.

  6. Ground reaction force adaptations to tripedal locomotion in dogs.

    Science.gov (United States)

    Fuchs, A; Goldner, B; Nolte, I; Schilling, N

    2014-09-01

    To gain insight into the adaptive mechanisms to tripedal locomotion and increase understanding of the biomechanical consequences of limb amputation, this study investigated kinetic and temporal gait parameters in dogs before and after the loss of a hindlimb was simulated. Nine clinically sound Beagle dogs trotted on an instrumented treadmill and the ground reaction forces as well as the footfall patterns were compared between quadrupedal and tripedal locomotion. Stride and stance durations decreased significantly in all limbs when the dogs ambulated tripedally, while relative stance duration increased. Both vertical and craniocaudal forces were significantly different in the remaining hindlimb. In the forelimbs, propulsive force increased in the contralateral and decreased in the ipsilateral limb, while the vertical forces were unchanged (except for mean force in the contralateral limb). Bodyweight was shifted to the contralateral and cranial body side so that each limb bore ~33% of the dog's bodyweight. The observed changes in the craniocaudal forces and the vertical impulse ratio between the fore- and hindlimbs suggest that a nose-up pitching moment occurs during the affected limb pair's functional step. To regain pitch balance for a given stride cycle, a nose-down pitching moment is exerted when the intact limb pair supports the body. These kinetic changes indicate a compensatory mechanism in which the unaffected diagonal limb pair is involved. Therefore, the intact support pair of limbs should be monitored closely in canine hindlimb amputees. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Data-driven stochastic modelling of zebrafish locomotion.

    Science.gov (United States)

    Zienkiewicz, Adam; Barton, David A W; Porfiri, Maurizio; di Bernardo, Mario

    2015-11-01

    In this work, we develop a data-driven modelling framework to reproduce the locomotion of fish in a confined environment. Specifically, we highlight the primary characteristics of the motion of individual zebrafish (Danio rerio), and study how these can be suitably encapsulated within a mathematical framework utilising a limited number of calibrated model parameters. Using data captured from individual zebrafish via automated visual tracking, we develop a model using stochastic differential equations and describe fish as a self propelled particle moving in a plane. Based on recent experimental evidence of the importance of speed regulation in social behaviour, we extend stochastic models of fish locomotion by introducing experimentally-derived processes describing dynamic speed regulation. Salient metrics are defined which are then used to calibrate key parameters of coupled stochastic differential equations, describing both speed and angular speed of swimming fish. The effects of external constraints are also included, based on experimentally observed responses. Understanding the spontaneous dynamics of zebrafish using a bottom-up, purely data-driven approach is expected to yield a modelling framework for quantitative investigation of individual behaviour in the presence of various external constraints or biological assays.

  8. Reciprocal locomotion of dense swimmers in Stokes flow

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Rodriguez, David [Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Lauga, Eric [Department of Mechanical and Aerospace Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0411 (United States)], E-mail: davidgr@alum.mit.edu, E-mail: elauga@ucsd.edu

    2009-05-20

    Due to the kinematic reversibility of Stokes flow, a body executing a reciprocal motion (a motion in which the sequence of body configurations remains identical under time reversal) cannot propel itself in a viscous fluid in the limit of negligible inertia; this result is known as Purcell's scallop theorem. In this limit, the Reynolds numbers based on the fluid inertia and on the body inertia are all zero. Previous studies characterized the breakdown of the scallop theorem with fluid inertia. In this paper we show that, even in the absence of fluid inertia, certain dense bodies undergoing reciprocal motion are able to swim. Using Lorentz's reciprocal theorem, we first derive the general differential equations that govern the locomotion kinematics of a dense swimmer. We demonstrate that no reciprocal swimming is possible if the body motion consists only of tangential surface deformation (squirming). We then apply our general formulation to compute the locomotion of four simple swimmers, each with a different spatial asymmetry, that perform normal surface deformations. We show that the resulting swimming speeds (or rotation rates) scale as the first power of a properly defined 'swimmer Reynolds number', demonstrating thereby a continuous breakdown of the scallop theorem with body inertia.

  9. Contact enhancement of locomotion in spreading cell colonies

    Science.gov (United States)

    D'Alessandro, Joseph; Solon, Alexandre P.; Hayakawa, Yoshinori; Anjard, Christophe; Detcheverry, François; Rieu, Jean-Paul; Rivière, Charlotte

    2017-10-01

    The dispersal of cells from an initially constrained location is a crucial aspect of many physiological phenomena, ranging from morphogenesis to tumour spreading. In such processes, cell-cell interactions may deeply alter the motion of single cells, and in turn the collective dynamics. While contact phenomena like contact inhibition of locomotion are known to come into play at high densities, here we focus on the little explored case of non-cohesive cells at moderate densities. We fully characterize the spreading of micropatterned colonies of Dictyostelium discoideum cells from the complete set of individual trajectories. From data analysis and simulation of an elementary model, we demonstrate that contact interactions act to speed up the early population spreading by promoting individual cells to a state of higher persistence, which constitutes an as-yet unreported contact enhancement of locomotion. Our findings also suggest that the current modelling paradigm of memoryless active particles may need to be extended to account for the history-dependent internal state of motile cells.

  10. Locomotion and drag in wet and dry granular media

    Science.gov (United States)

    Goldman, Daniel; Kuckuk, Robyn; Sharpe, Sarah

    2015-03-01

    Many animals move within substrates such as soil and dry sand; the resistive properties of such granular materials (GM) can depend on water content and compaction, but little is known about how such parameters affect locomotion or the relevant physics of drag and penetration. We developed a system to create homogeneous wet GM of varying moisture content and compaction in quantities sufficient to study the burial and subsurface locomotion of the Ocellated skink (C. ocellatus) a desert-generalist lizard. X-ray imaging revealed that in wet and dry GM the lizard slowly buried (~ 30 seconds) propagating a wave from head to tail, while moving in a start-stop motion. During forward movement, the head oscillated, and the forelimb on the convex side of the body propelled the animal. Although body kinematics (and ``slip'') were similar in both substrates, the burial depth was smaller in wet GM. Penetration and drag force experiments on smooth cylinders revealed that wet GM was ~ 3 × more resistive than dry GM, suggesting that during burial the lizard operated near its maximum force producing capability and was thus constrained by environmental properties. work supported by NSF PoLS.

  11. Spatial assignment of emissions using a new locomotive emissions model.

    Science.gov (United States)

    Gould, Gregory M; Niemeier, Deb A

    2011-07-01

    Estimates of fuel use and air pollutant emissions from freight rail currently rely highly on aggregate methods and largely obsolete data which offer little insight into contemporary air quality problems. Because the freight industry is for the most part privately held and data are closely guarded for competitive reasons, the challenge is to produce robust estimates using current reporting requirements, while accurately portraying the spatial nature of freight rail impacts. This research presents a new spatially resolved model for estimating air pollutant emissions (hydrocarbons, carbon monoxide, nitrogen oxides, particulate matter less than 10 μm in diameter, sulfur dioxide, and carbon dioxide) from locomotives. Emission estimates are based on track segment level data including track grade, type of train traffic (bulk, intermodal, or manifest) and the local locomotive fleet (EPA tier certification level and fuel efficiency). We model the California Class I freight rail system and compare our results to regional estimates from the California Air Resources Board and to estimates following U.S. Environmental Protection Agency guidance. We find that our results vary considerably from the other methods depending on the region or corridor analyzed. We also find large differences in fuel and emission intensity for individual rail corridors.

  12. Crawling beneath the free surface: Water snail locomotion

    Science.gov (United States)

    Lee, Sungyon; Bush, John W. M.; Hosoi, A. E.; Lauga, Eric

    2008-08-01

    Land snails move via adhesive locomotion. Through muscular contraction and expansion of their foot, they transmit waves of shear stress through a thin layer of mucus onto a solid substrate. Since a free surface cannot support shear stress, adhesive locomotion is not a viable propulsion mechanism for water snails that travel inverted beneath the free surface. Nevertheless, the motion of the freshwater snail, Sorbeoconcha physidae, is reminiscent of that of its terrestrial counterparts, being generated by the undulation of the snail foot that is separated from the free surface by a thin layer of mucus. Here, a lubrication model is used to describe the mucus flow in the limit of small-amplitude interfacial deformations. By assuming the shape of the snail foot to be a traveling sine wave and the mucus to be Newtonian, an evolution equation for the interface shape is obtained and the resulting propulsive force on the snail is calculated. This propulsive force is found to be nonzero for moderate values of the capillary number but vanishes in the limits of high and low capillary number. Physically, this force arises because the snail's foot deforms the free surface, thereby generating curvature pressures and lubrication flows inside the mucus layer that couple to the topography of the foot.

  13. Hopping locomotion at different gravity: metabolism and mechanics in humans.

    Science.gov (United States)

    Pavei, Gaspare; Minetti, Alberto E

    2016-05-15

    Previous literature on the effects of low gravity on the mechanics and energetics of human locomotion already dealt with walking, running, and skipping. The aim of the present study is to obtain a comprehensive view on that subject by including measurements of human hopping in simulated low gravity, a gait often adopted in many Apollo Missions and documented in NASA footage. Six subjects hopped at different speeds at terrestrial, Martian, and Lunar gravity on a treadmill while oxygen consumption and 3D body kinematic were sampled. Results clearly indicate that hopping is too metabolically expensive to be a sustainable locomotion on Earth but, similarly to skipping (and running), its economy greatly (more than ×10) increases at lower gravity. On the Moon, the metabolic cost of hopping becomes even lower than that of walking, skipping, and running, but the general finding is that gaits with very different economy on Earth share almost the same economy on the Moon. The mechanical reasons for such a decrease in cost are discussed in the paper. The present data, together with previous findings, will allow also to predict the aerobic traverse range/duration of astronauts when getting far from their base station on low gravity planets. Copyright © 2016 the American Physiological Society.

  14. Effects of wearing lower leg compression sleeves on locomotion economy.

    Science.gov (United States)

    Kurz, Eduard; Anders, Christoph

    2018-02-15

    The purpose of this investigation was to assess the effect of compression sleeves on muscle activation cost during locomotion. Twenty-two recreationally active men (age: 25 ± 3 years) ran on a treadmill at four different speeds (ordered sequence of 2.8, 3.3, 2.2, and 3.9 m/s). The tests were performed without (control situation, CON) and while wearing specially designed lower leg compression sleeves (SL). Myoelectric activity of five lower leg muscles (tibialis anterior, fibularis longus, lateral and medial head of gastrocnemius, and soleus) was captured using Surface EMG. To assess muscle activation cost, the cumulative muscle activity per distance travelled (CMAPD) of the CON and SL situations was determined. Repeated measures analyses of variance were performed separately for each muscle. The analyses revealed a reduced lower leg muscle activation cost with respect to test situation for SL for all muscles (p  0.18). The respective significant reductions of CMAPD values during SL ranged between 4% and 16% and were largest at 2.8 m/s. The findings presented point towards an improved muscle activation cost while wearing lower leg compression sleeves during locomotion that have potential to postpone muscle fatigue.

  15. Locomotion and Grasping impairment in preschoolers with autism spectrum disorder

    Directory of Open Access Journals (Sweden)

    Francesca Fulceri

    2015-08-01

    Full Text Available Objective: To investigate expressiveness of motor impairment in autism spectrum disorder (ASD and its correlation with developmental and clinical features of ASD. Method: Thirty-five male preschoolers with ASD completed the Peabody Developmental Motor Scales-2 (PDMS-2; Folio and Fewell, 2000 and underwent a multidisciplinary assessment including medical examination, standardized assessment of cognitive abilities, administration of Autism_Diagnostic_Observation_Schedule (ADOS and a parent interview about adaptive skills. Results: Results revealed a substantial impairment in locomotion and grasping skills. Both fine and gross motor skills were significantly correlated with non verbal IQ and adaptive behaviours (p<0.01 but not with chronological age or ADOS scores. Children with weaker motor skills have greater cognitive and adaptive behaviours deficits. Conclusions: Motor development in ASD can be detected at preschool age and locomotion and grasping skills are substantially the most impaired area. These findings support the need to assess motor skills in preschoolers with ASD in addition to other developmental skill areas. Along with the increasingly acknowledged importance of motor skills for subsequent social, cognitive, and communicative development our findings support the need to consider motor intervention as a key area in therapeutic program to improve outcome in preschoolers with ASD.

  16. Hybrid magnetic mechanism for active locomotion based on inchworm motion

    International Nuclear Information System (INIS)

    Kim, Sung Hoon; Hashi, Shuichiro; Ishiyama, Kazushi

    2013-01-01

    Magnetic robots have been studied in the past. Insect-type micro-robots are used in various biomedical applications; researchers have developed inchworm micro-robots for endoscopic use. A biological inchworm has a looping locomotion gait. However, most inchworm micro-robots depend on a general bending, or bellows, motion. In this paper, we introduce a new robotic mechanism using magnetic force and torque control in a rotating magnetic field for a looping gait. The proposed robot is controlled by the magnetic torque, attractive force, and body mechanisms (two stoppers, flexible body, and different frictional legs). The magnetic torque generates a general bending motion. In addition, the attractive force and body mechanisms produce the robot’s looping motion within a rotating magnetic field and without the use of an algorithm for field control. We verified the device’s performance and analyzed the motion through simulations and various experiments. The robot mechanism can be applied to active locomotion for various medical robots, such as wireless endoscopes. (technical note)

  17. Controlling legs for locomotion-insights from robotics and neurobiology.

    Science.gov (United States)

    Buschmann, Thomas; Ewald, Alexander; von Twickel, Arndt; Büschges, Ansgar

    2015-06-29

    Walking is the most common terrestrial form of locomotion in animals. Its great versatility and flexibility has led to many attempts at building walking machines with similar capabilities. The control of walking is an active research area both in neurobiology and robotics, with a large and growing body of work. This paper gives an overview of the current knowledge on the control of legged locomotion in animals and machines and attempts to give walking control researchers from biology and robotics an overview of the current knowledge in both fields. We try to summarize the knowledge on the neurobiological basis of walking control in animals, emphasizing common principles seen in different species. In a section on walking robots, we review common approaches to walking controller design with a slight emphasis on biped walking control. We show where parallels between robotic and neurobiological walking controllers exist and how robotics and biology may benefit from each other. Finally, we discuss where research in the two fields diverges and suggest ways to bridge these gaps.

  18. Fluid Flow Simulation and Energetic Analysis of Anomalocarididae Locomotion

    Science.gov (United States)

    Mikel-Stites, Maxwell; Staples, Anne

    2014-11-01

    While an abundance of animal locomotion simulations have been performed modeling the motions of living arthropods and aquatic animals, little quantitative simulation and reconstruction of gait parameters has been done to model the locomotion of extinct animals, many of which bear little physical resemblance to their modern descendants. To that end, this project seeks to analyze potential swimming patterns used by the anomalocaridid family, (specifically Anomalocaris canadensis, a Cambrian Era aquatic predator), and determine the most probable modes of movement. This will serve to either verify or cast into question the current assumed movement patterns and properties of these animals and create a bridge between similar flexible-bodied swimmers and their robotic counterparts. This will be accomplished by particle-based fluid flow simulations of the flow around the fins of the animal, as well as an energy analysis of a variety of sample gaits. The energy analysis will then be compared to the extant information regarding speed/energy use curves in an attempt to determine which modes of swimming were most energy efficient for a given range of speeds. These results will provide a better understanding of how these long-extinct animals moved, possibly allowing an improved understanding of their behavioral patterns, and may also lead to a novel potential platform for bio-inspired underwater autonomous vehicles (UAVs).

  19. Jumping robots: a biomimetic solution to locomotion across rough terrain.

    Science.gov (United States)

    Armour, Rhodri; Paskins, Keith; Bowyer, Adrian; Vincent, Julian; Megill, William; Bomphrey, Richard

    2007-09-01

    This paper introduces jumping robots as a means to traverse rough terrain; such terrain can pose problems for traditional wheeled, tracked and legged designs. The diversity of jumping mechanisms found in nature is explored to support the theory that jumping is a desirable ability for a robot locomotion system to incorporate, and then the size-related constraints are determined from first principles. A series of existing jumping robots are presented and their performance summarized. The authors present two new biologically inspired jumping robots, Jollbot and Glumper, both of which incorporate additional locomotion techniques of rolling and gliding respectively. Jollbot consists of metal hoop springs forming a 300 mm diameter sphere, and when jumping it raises its centre of gravity by 0.22 m and clears a height of 0.18 m. Glumper is of octahedral shape, with four 'legs' that each comprise two 500 mm lengths of CFRP tube articulating around torsion spring 'knees'. It is able to raise its centre of gravity by 1.60 m and clears a height of 1.17 m. The jumping performance of the jumping robot designs presented is discussed and compared against some specialized jumping animals. Specific power output is thought to be the performance-limiting factor for a jumping robot, which requires the maximization of the amount of energy that can be stored together with a minimization of mass. It is demonstrated that this can be achieved through optimization and careful materials selection.

  20. Fluctuation-induced switching and the switching path distribution.

    Science.gov (United States)

    Dykman, Mark

    2009-03-01

    Fluctuation-induced switching is at the root of diverse phenomena currently studied in Josephson junctions, nano-mechanical systems, nano-magnets, and optically trapped atoms. In a fluctuation leading to switching the system must overcome an effective barrier, making switching events rare, for low fluctuation intensity. We will provide an overview of the methods of finding the switching barrier for systems away from thermal equilibrium. Generic features of the barrier, such as scaling with the system parameters, will be discussed. We will also discuss the motion of the system in switching and the ways of controlling it. Two major classes of systems will be considered: dynamical systems, where fluctuations are induced by noise, and birth-death systems. Even though the motion during switching is random, the paths followed in switching form a narrow tube in phase space of the system centered at the most probable path. The paths distribution is generally Gaussian and has specific features, which have been seen in the experiment [1]. Finding the most probable path itself can be reduced to solving a problem of Hamiltonian dynamics of an auxiliary noise-free system. The solution also gives the switching barrier. The barrier can be found explicitly close to parameter values where the number of stable states of the system changes and the dynamics is controlled by a slow variable. The scaling of the barrier height depends on the type of the corresponding bifurcation. We show that, both for birth-death and for Gaussian noise driven systems, the presence of even weak non-Gaussian noise can strongly modify the switching rate. The effect is described in a simple explicit form [2,3]. Weak deviations of the noise statistics from Gaussian can be sensitively detected using balanced dynamical bridge, where this deviation makes the populations of coexisting stable states different from each other; a realization of such a bridge will be discussed. We will also discuss the sharp

  1. A Specific Population of Reticulospinal Neurons Controls the Termination of Locomotion

    Directory of Open Access Journals (Sweden)

    Laurent Juvin

    2016-06-01

    Full Text Available Locomotion requires the proper sequencing of neural activity to start, maintain, and stop it. Recently, brainstem neurons were shown to specifically stop locomotion in mammals. However, the cellular properties of these neurons and their activity during locomotion are still unknown. Here, we took advantage of the lamprey model to characterize the activity of a cell population that we now show to be involved in stopping locomotion. We find that these neurons display a burst of spikes that coincides with the end of swimming activity. Their pharmacological activation ends ongoing swimming, whereas the inactivation of these neurons dramatically impairs the rapid termination of swimming. These neurons are henceforth referred to as stop cells, because they play a crucial role in the termination of locomotion. Our findings contribute to the fundamental understanding of motor control and provide important details about the cellular mechanisms involved in locomotor termination.

  2. [The concept and definition of locomotive syndrome in a super-aged society].

    Science.gov (United States)

    Nakamura, Kozo; Yoshimura, Noriko; Akune, Toru; Ogata, Toru; Tanaka, Sakae

    2014-10-01

    The population of elderly individuals who need nursing care is rapidly increasing in Japan. Locomotive syndrome involves a decrease in mobility due to locomotive organ dysfunction, and increases risk for dependency on nursing care service. Because gait speed and chair stand time are correlated with such risks, patients with locomotive syndrome are assessed using brief methods such as the two-step test, which involves dividing the maximum stride length by the height of the patient, and the stand-up test, which involves standing on one or both legs at different heights. One leg standing and squatting are recommended as beneficial locomotive home exercises. Locomotive syndrome has been recognized widely in Japan, and included in the National Health Promotion Movement (2013-2022).

  3. 21st Century Locomotive Technology: 2003 Annual Technical Status Report DOE/AL68284-TSR03

    Energy Technology Data Exchange (ETDEWEB)

    Lembit Salasoo

    2004-01-09

    The 21st Century Locomotive program objective is to develop 25% more efficient freight locomotives by 2010. Diesel engine-related research addresses advanced fuel injection, electric turbocharger and abradable seals. Assembly of a common rail fuel injection test system is underway, and a CFD combustion model has been validated. An electrically assisted turbocharger has been constructed and operated, meeting the generator mode design rating. System characterization and optimization is ongoing. Candidate abradable seal materials have been identified and test coupons prepared. Locomotive system-related research addresses capturing, storing and utilizing regenerative braking energy in a hybrid locomotive, and fuel optimization control. Hybrid locomotive energy storage requirements have been identified and studies on specific energy storage solutions are in progress. Energy management controls have been defined and testing initiated. Train and track parameter identification necessary for fuel optimization has been demonstrated.

  4. A Specific Population of Reticulospinal Neurons Controls the Termination of Locomotion.

    Science.gov (United States)

    Juvin, Laurent; Grätsch, Swantje; Trillaud-Doppia, Emilie; Gariépy, Jean-François; Büschges, Ansgar; Dubuc, Réjean

    2016-06-14

    Locomotion requires the proper sequencing of neural activity to start, maintain, and stop it. Recently, brainstem neurons were shown to specifically stop locomotion in mammals. However, the cellular properties of these neurons and their activity during locomotion are still unknown. Here, we took advantage of the lamprey model to characterize the activity of a cell population that we now show to be involved in stopping locomotion. We find that these neurons display a burst of spikes that coincides with the end of swimming activity. Their pharmacological activation ends ongoing swimming, whereas the inactivation of these neurons dramatically impairs the rapid termination of swimming. These neurons are henceforth referred to as stop cells, because they play a crucial role in the termination of locomotion. Our findings contribute to the fundamental understanding of motor control and provide important details about the cellular mechanisms involved in locomotor termination. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

  5. Multibody system dynamics for bio-inspired locomotion: from geometric structures to computational aspects.

    Science.gov (United States)

    Boyer, Frédéric; Porez, Mathieu

    2015-03-26

    This article presents a set of generic tools for multibody system dynamics devoted to the study of bio-inspired locomotion in robotics. First, archetypal examples from the field of bio-inspired robot locomotion are presented to prepare the ground for further discussion. The general problem of locomotion is then stated. In considering this problem, we progressively draw a unified geometric picture of locomotion dynamics. For that purpose, we start from the model of discrete mobile multibody systems (MMSs) that we progressively extend to the case of continuous and finally soft systems. Beyond these theoretical aspects, we address the practical problem of the efficient computation of these models by proposing a Newton-Euler-based approach to efficient locomotion dynamics with a few illustrations of creeping, swimming, and flying.

  6. Can Clinical Assessment of Locomotive Body Function Explain Gross Motor Environmental Performance in Cerebral Palsy?

    Science.gov (United States)

    Sanz Mengibar, Jose Manuel; Santonja-Medina, Fernando; Sanchez-de-Muniain, Paloma; Canteras-Jordana, Manuel

    2016-03-01

    Gross Motor Function Classification System has discriminative purposes but does not assess short-term therapy goals. Locomotion Stages (LS) classify postural body functions and independent activity components. Assessing the relation between Gross Motor Function Classification System level and Locomotion Stages will make us understand if clinical assessment can explain and predict motor environmental performance in cerebral palsy. A total of 462 children were assessed with both scales. High reliability and strong negative correlation (-0.908) for Gross Motor Function Classification System and Locomotion Stages at any age was found. Sensitivity was 83%, and specificity and positive predictive value were 100% within the same age range. Regression analysis showed detailed probabilities for the realization of the Gross Motor Function Classification System depending on the Locomotion Stages and the age group. Postural body function measure with Locomotion Stages is reliable, sensitive, and specific for gross motor function and able to predict environmental performance. © The Author(s) 2015.

  7. Identification of a brainstem circuit regulating visual cortical state in parallel with locomotion.

    Science.gov (United States)

    Lee, A Moses; Hoy, Jennifer L; Bonci, Antonello; Wilbrecht, Linda; Stryker, Michael P; Niell, Cristopher M

    2014-07-16

    Sensory processing is dependent upon behavioral state. In mice, locomotion is accompanied by changes in cortical state and enhanced visual responses. Although recent studies have begun to elucidate intrinsic cortical mechanisms underlying this effect, the neural circuits that initially couple locomotion to cortical processing are unknown. The mesencephalic locomotor region (MLR) has been shown to be capable of initiating running and is associated with the ascending reticular activating system. Here, we find that optogenetic stimulation of the MLR in awake, head-fixed mice can induce both locomotion and increases in the gain of cortical responses. MLR stimulation below the threshold for overt movement similarly changed cortical processing, revealing that MLR's effects on cortex are dissociable from locomotion. Likewise, stimulation of MLR projections to the basal forebrain also enhanced cortical responses, suggesting a pathway linking the MLR to cortex. These studies demonstrate that the MLR regulates cortical state in parallel with locomotion. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. A Switch Is Not a Switch: Syntactically-Driven Bilingual Language Control

    Science.gov (United States)

    Gollan, Tamar H.; Goldrick, Matthew

    2018-01-01

    The current study investigated the possibility that language switches could be relatively automatically triggered by context. "Single-word switches," in which bilinguals switched languages on a single word in midsentence and then immediately switched back, were contrasted with more complete "whole-language switches," in which…

  9. Switching Activity Estimation of CIC Filter Integrators

    OpenAIRE

    Abbas, Muhammad; Gustafsson, Oscar

    2010-01-01

    In this work, a method for estimation of the switching activity in integrators is presented. To achieve low power, it is always necessary to develop accurate and efficient methods to estimate the switching activity. The switching activities are then used to estimate the power consumption. In our work, the switching activity is first estimated for the general purpose integrators and then it is extended for the estimation of switching activity in cascaded integrators in CIC filters. ©2010 I...

  10. Principles of broadband switching and networking

    CERN Document Server

    Liew, Soung C

    2010-01-01

    An authoritative introduction to the roles of switching and transmission in broadband integrated services networks Principles of Broadband Switching and Networking explains the design and analysis of switch architectures suitable for broadband integrated services networks, emphasizing packet-switched interconnection networks with distributed routing algorithms. The text examines the mathematical properties of these networks, rather than specific implementation technologies. Although the pedagogical explanations in this book are in the context of switches, many of the fundamenta

  11. DEFINITION OF LOCOMOTIVE TRACTION FORCE WITH REGARD TO UNEVEN LOADING OF WHEEL-MOTOR BLOCK

    Directory of Open Access Journals (Sweden)

    B. Ye. Bodnar

    2013-11-01

    Full Text Available Purpose. The article describes the most common methods for determining the locomotive traction force. Solving the tasks of traction calculations involves determination of the forces influencing the train at every point of the way. When choosing a rational trajectory of the train motion and the development of operational regulations of train driving it is necessary to determine the actual value of the locomotive traction force. Considering various factors, power value of traction electric motor of locomotive may have significant differences. Advancement of the operational definition system of the locomotive traction force during the calculations by electrical parameters of traction electric motor with regard to uneven load of wheel-motor block is the purpose of the article. Methodology. The method of determining the traction force of locomotives and diesel locomotives with electric transmission, which is based on primary data acquisition of traction electric engines of direct current behavior, was proposed. Sensors and their integration into the electrical circuitry of the locomotive in order to get the data in digital form and for operational calculation of the each traction motor mode and the definition of locomotive traction force are presented. Findings. The experimental investigation of the system of locomotive traction force determination with the electric traction motor ED-105 was offered. A comparison of electrical and mechanical power of the electric motor was conducted. Originality. The system of locomotives power operational definition, which takes into account the variable electro-mechanical factors of wheel and motor blocks and increases the accuracy of the calculations, was proposed. Practical value. The system is a part of an onboard complex in definition of energy-efficient regimes for trains movement and provides the definition of accelerating and decelerating forces.

  12. Cholinergic mechanisms in spinal locomotion-potential target for rehabilitation approaches.

    Science.gov (United States)

    Jordan, Larry M; McVagh, J R; Noga, B R; Cabaj, A M; Majczyński, H; Sławińska, Urszula; Provencher, J; Leblond, H; Rossignol, Serge

    2014-01-01

    Previous experiments implicate cholinergic brainstem and spinal systems in the control of locomotion. Our results demonstrate that the endogenous cholinergic propriospinal system, acting via M2 and M3 muscarinic receptors, is capable of consistently producing well-coordinated locomotor activity in the in vitro neonatal preparation, placing it in a position to contribute to normal locomotion and to provide a basis for recovery of locomotor capability in the absence of descending pathways. Tests of these suggestions, however, reveal that the spinal cholinergic system plays little if any role in the induction of locomotion, because MLR-evoked locomotion in decerebrate cats is not prevented by cholinergic antagonists. Furthermore, it is not required for the development of stepping movements after spinal cord injury, because cholinergic agonists do not facilitate the appearance of locomotion after spinal cord injury, unlike the dramatic locomotion-promoting effects of clonidine, a noradrenergic α-2 agonist. Furthermore, cholinergic antagonists actually improve locomotor activity after spinal cord injury, suggesting that plastic changes in the spinal cholinergic system interfere with locomotion rather than facilitating it. Changes that have been observed in the cholinergic innervation of motoneurons after spinal cord injury do not decrease motoneuron excitability, as expected. Instead, the development of a "hyper-cholinergic" state after spinal cord injury appears to enhance motoneuron output and suppress locomotion. A cholinergic suppression of afferent input from the limb after spinal cord injury is also evident from our data, and this may contribute to the ability of cholinergic antagonists to improve locomotion. Not only is a role for the spinal cholinergic system in suppressing locomotion after SCI suggested by our results, but an obligatory contribution of a brainstem cholinergic relay to reticulospinal locomotor command systems is not confirmed by our experiments.

  13. 49 CFR Appendix B to Part 240 - Procedures for Submission and Approval of Locomotive Engineer Qualification Programs

    Science.gov (United States)

    2010-10-01

    ... Locomotive Engineer Qualification Programs B Appendix B to Part 240 Transportation Other Regulations Relating... QUALIFICATION AND CERTIFICATION OF LOCOMOTIVE ENGINEERS Pt. 240, App. B Appendix B to Part 240—Procedures for Submission and Approval of Locomotive Engineer Qualification Programs This appendix establishes procedures...

  14. Switching dynamics of TaOx-based threshold switching devices

    Science.gov (United States)

    Goodwill, Jonathan M.; Gala, Darshil K.; Bain, James A.; Skowronski, Marek

    2018-03-01

    Bi-stable volatile switching devices are being used as access devices in solid-state memory arrays and as the active part of compact oscillators. Such structures exhibit two stable states of resistance and switch between them at a critical value of voltage or current. A typical resistance transient under a constant amplitude voltage pulse starts with a slow decrease followed by a rapid drop and leveling off at a low steady state value. This behavior prompted the interpretation of initial delay and fast transition as due to two different processes. Here, we show that the entire transient including incubation time, transition time, and the final resistance values in TaOx-based switching can be explained by one process, namely, Joule heating with the rapid transition due to the thermal runaway. The time, which is required for the device in the conducting state to relax back to the stable high resistance one, is also consistent with the proposed mechanism.

  15. IGBT: a solid state switch

    International Nuclear Information System (INIS)

    Chatroux, D.; Maury, J.; Hennevin, B.

    1993-01-01

    A Copper Vapour Laser Power Supply has been designed using a solid state switch consisting in eighteen Isolated Gate Bipolar Transistors (IGBT), -1200 volts, 400 Amps, each-in parallel. This paper presents the Isolated Gate Bipolar Transistor (IGBTs) replaced in the Power Electronic components evolution, and describes the IGBT conduction mechanism, presents the parallel association of IGBTs, and studies the application of these components to a Copper Vapour Laser Power Supply. The storage capacitor voltage is 820 volts, the peak current of the solid state switch is 17.000 Amps. The switch is connected on the primary of a step-up transformer, followed by a magnetic modulator. The reset of the magnetic modulator is provided by part of the laser reflected energy with a patented circuit. The charging circuit is a resonant circuit with a charge controlled by an IGBT switch. When the switch is open, the inductance energy is free-wheeled by an additional winding and does not extend the charging phase of the storage capacitor. The design allows the storage capacitor voltage to be very well regulated. This circuit is also patented. The electric pulse in the laser has 30.000 Volt peak voltage, 2000 Amp peak current, and is 200 nanoseconds long, for a 200 Watt optical power Copper Vapour Laser

  16. Photoresistance switching of plasmonic nanopores.

    Science.gov (United States)

    Li, Yi; Nicoli, Francesca; Chen, Chang; Lagae, Liesbet; Groeseneken, Guido; Stakenborg, Tim; Zandbergen, Henny W; Dekker, Cees; Van Dorpe, Pol; Jonsson, Magnus P

    2015-01-14

    Fast and reversible modulation of ion flow through nanosized apertures is important for many nanofluidic applications, including sensing and separation systems. Here, we present the first demonstration of a reversible plasmon-controlled nanofluidic valve. We show that plasmonic nanopores (solid-state nanopores integrated with metal nanocavities) can be used as a fluidic switch upon optical excitation. We systematically investigate the effects of laser illumination of single plasmonic nanopores and experimentally demonstrate photoresistance switching where fluidic transport and ion flow are switched on or off. This is manifested as a large (∼ 1-2 orders of magnitude) increase in the ionic nanopore resistance and an accompanying current rectification upon illumination at high laser powers (tens of milliwatts). At lower laser powers, the resistance decreases monotonically with increasing power, followed by an abrupt transition to high resistances at a certain threshold power. A similar rapid transition, although at a lower threshold power, is observed when the power is instead swept from high to low power. This hysteretic behavior is found to be dependent on the rate of the power sweep. The photoresistance switching effect is attributed to plasmon-induced formation and growth of nanobubbles that reversibly block the ionic current through the nanopore from one side of the membrane. This explanation is corroborated by finite-element simulations of a nanobubble in the nanopore that show the switching and the rectification.

  17. The equine neck and its function during movement and locomotion.

    Science.gov (United States)

    Zsoldos, Rebeka R; Licka, Theresia F

    2015-10-01

    During both locomotion and body movements at stance, the head and neck of the horse are a major craniocaudal and lateral balancing mechanism employing input from the visual, vestibular and proprioceptive systems. The function of the equine neck has recently become the focus of several research groups; this is probably also feeding on an increase of interest in the equine neck in equestrian sports, with a controversial discussion of specific neck positions such as maximum head and neck flexion. The aim of this review is to offer an overview of new findings on the structures and functions of the equine neck, illustrating their interplay. The movement of the neck is based on intervertebral motion, but it is also an integral part of locomotion; this is illustrated by the different neck conformations in the breeds of horses used for various types of work. The considerable effect of the neck movement and posture onto the whole trunk and even the limbs is transmitted via bony, ligamentous and muscular structures. Also, the fact that the neck position can easily be influenced by the rider and/or by the employment of training aids makes it an important avenue for training of new movements of the neck as well as the whole horse. Additionally, the neck position also affects the cervical spinal cord as well as the roots of the spinal nerves; besides the commonly encountered long-term neurological effects of cervical vertebral disorders, short-term changes of neural and muscular function have also been identified in the maximum flexion of the cranial neck and head position. During locomotion, the neck stores elastic energy within the passive tissues such as ligaments, joint capsules and fasciae. For adequate stabilisation, additional muscle activity is necessary; this is learned and requires constant muscle training as it is essential to prevent excessive wear and tear on the vertebral joints and also repetitive or single trauma to the spinal nerves and the spinal cord. The

  18. PROSPECTS OF THE PRIVATE LOCOMOTIVES USAGE FOR GOODS TRAFFIC IN THE DIRECTION OF SEA PORTS

    Directory of Open Access Journals (Sweden)

    D. M. Kozachenko

    2017-12-01

    Full Text Available Purpose. At the present time, Ukraine's mainline railway transport is entirely in state ownership. Ukraine has undertaken to implement the European Union Directives providing of non-discriminatory access to the railway infrastructure of independent carriers. A considerable quantity of options significantly affects the working conditions of carriers that do not depend on Ukrzaliznytsia. One of the tasks that arises when performing transportation by independent carriers is the organization of private locomotives operation and their servicing by engine crews. The purpose of the article is to evaluate the technical characteristic of the private locomotives usage in order to perform goods traffic in the direction of sea ports. Methodology. The researches were carried out on the basis of methods for organizing the operational work of railways and methods of traction calculations. Findings. The paper highlights the problem of goods traffic organization to seaports by independent carriers. It determines the requirements for equipment for diesel locomotives and electric locomotives depending on the distance of transportation. Permissible distances that can be served by engine crews in performing the requirements for the duration of their continuous operation were also determined. Schemes of infrastructure objects location for the locomotives and engine crews operation have been developed. It was established that diesel locomotives of independent carriers will be able to serve transportation between loading and unloading stations up to 822 km, and electric locomotives up to 1000 km with the construction of the main part of the locomotive infrastructure at the port station. The performed calculations show the potential coverage of rail transportation to sea ports by independent carriers with the use of its own locomotive infrastructure. To define more exactly the haul length of train servicing by locomotives and locomotives by engine crews, it is necessary

  19. Portable Userspace Virtual Filesystem Switch

    Directory of Open Access Journals (Sweden)

    Łukasz Faber

    2013-01-01

    Full Text Available Multiple different filesystems — including disk-based, network, distributed, abstract — arean integral part of every operating system. They are usually written as kernel modules and abstracted to the user via a virtual filesystem switch. In this paper we analyse the feasibility of reimplementing the virtual filesystem switch as a userspace daemon and applicability of this approach in real-life usage. Such reimplementation will require a way to virtualise processes behaviour related to filesystem operations. The problem is non-trivial, as we assume limited capabilities of the VFS switch implemented in userspace. We present a layered architecture comprising of a monitoring process, the VFS abstraction and real filesystem implementations. All working in userspace. Then, we evaluate this solution in four areas: portability, feasibility, usability and performance. Our results demonstrate possible gains in using the userspace-based approach with monolithic kernels, but also underline problems that are encountered in this approach.

  20. All-fiber polarization switch

    Science.gov (United States)

    Knape, Harald; Margulis, Walter

    2007-03-01

    We report an all-fiber polarization switch made out of silica-based microstructured fiber suitable for Q-switching all-fiber lasers. Nanosecond high-voltage pulses are used to heat and expand an internal electrode to cause λ/2-polarization rotation in less than 10 ns for 1.5 μm light. The 10 cm long component has an experimentally measured optical insertion loss of 0.2 dB and a 0-10 kHz repetition frequency capacity and has been durability tested for more than 109 pulses.

  1. Industry switching in developing countries

    DEFF Research Database (Denmark)

    Newman, Carol; Rand, John; Tarp, Finn

    2013-01-01

    Firm turnover (i.e., firm entry and exit) is a well-recognized source of sector-level productivity growth. In contrast, the role and importance of firms that switch activities from one sector to another is not well understood. Firm switchers are likely to be unique, differing from both newly...... and behavior than do entry and exit firms. Switchers tend to be labor intensive and to seek competitive opportunities in labor-intensive sectors in response to changes in market environments. Moreover, resource reallocation resulting from switching forms an important component of productivity growth. The topic...

  2. CMOS integrated switching power converters

    CERN Document Server

    Villar-Pique, Gerard

    2011-01-01

    This book describes the structured design and optimization of efficient, energy processing integrated circuits. The approach is multidisciplinary, covering the monolithic integration of IC design techniques, power electronics and control theory. In particular, this book enables readers to conceive, synthesize, design and implement integrated circuits with high-density high-efficiency on-chip switching power regulators. Topics covered encompass the structured design of the on-chip power supply, efficiency optimization, IC-compatible power inductors and capacitors, power MOSFET switches and effi

  3. Building a better snail: Lubrication and adhesive locomotion

    Science.gov (United States)

    Chan, Brian; Balmforth, N. J.; Hosoi, A. E.

    2005-11-01

    Many gastropods, such as slugs and snails, crawl via an unusual mechanism known as adhesive locomotion. We investigate this method of propulsion using two mathematical models: one for direct waves and one for retrograde waves. We then test the effectiveness of both proposed mechanisms by constructing two mechanical crawlers. Each crawler uses a different mechanical strategy to move on a thin layer of viscous fluid. The first uses a flexible flapping sheet to generate lubrication pressures in a Newtonian fluid, which in turn propel the mechanical snail. The second generates a wave of compression on a layer of Laponite, a non-Newtonian, finite-yield stress fluid with characteristics similar to those of snail mucus. This second design can climb smooth vertical walls and perform an inverted traverse.

  4. System Design and Locomotion of Superball, an Untethered Tensegrity Robot

    Science.gov (United States)

    Sabelhaus, Andrew P.; Bruce, Jonathan; Caluwaerts, Ken; Manovi, Pavlo; Firoozi, Roya Fallah; Dobi, Sarah; Agogino, Alice M.; Sunspiral, Vytas

    2015-01-01

    The Spherical Underactuated Planetary Exploration Robot ball (SUPERball) is an ongoing project within NASA Ames Research Center's Intelligent Robotics Group and the Dynamic Tensegrity Robotics Lab (DTRL). The current SUPERball is the first full prototype of this tensegrity robot platform, eventually destined for space exploration missions. This work, building on prior published discussions of individual components, presents the fully-constructed robot. Various design improvements are discussed, as well as testing results of the sensors and actuators that illustrate system performance. Basic low-level motor position controls are implemented and validated against sensor data, which show SUPERball to be uniquely suited for highly dynamic state trajectory tracking. Finally, SUPERball is shown in a simple example of locomotion. This implementation of a basic motion primitive shows SUPERball in untethered control.

  5. Bipedal locomotion: toward unified concepts in robotics and neuroscience.

    Science.gov (United States)

    Azevedo, Christine; Espiau, Bernard; Amblard, Bernard; Assaiante, Christine

    2007-02-01

    This review is the result of a joint reflection carried out by researchers in the fields of robotics and automatic control on the one hand and neuroscience on the other, both trying to answer the same question: what are the functional bases of bipedal locomotion and how can they be controlled? The originality of this work is to synthesize the two approaches in order to take advantage of the knowledge concerning the adaptability and reactivity performances of humans and of the rich tools and formal concepts available in biped robotics. Indeed, we claim that the theoretical framework of robotics can enhance our understanding of human postural control by formally expressing the experimental concepts used in neuroscience. Conversely, biological knowledge of human posture and gait can inspire biped robot design and control. Therefore, both neuroscientists and roboticists should find useful information in this paper.

  6. Dynamic control of biped locomotion robot using optimal regulator

    Energy Technology Data Exchange (ETDEWEB)

    Sano, Akihito; Furusho, Junji

    1988-08-01

    For moving in indoor space, it is generally recognized that biped locomotion is suitable. This paper proposes a hierarchical control strategy for the lower level where the position control or the force control at each joint is implemented. In the upper level control, the robot motion is divided into a sagittal plane and a lateral plane. We applied the optimal control algorithm to the motion control in the lateral plane in order to improve the robustness of the control system. The effects of these control schemes are shown by the experiments using the new walking robot BLR-G 1 and the parallel calculation system. BLR-G 1 has 9 degrees of freedom and equips the foot-pressure-sensors and a rate gyroscope. Complete dynamic walking is realized, in which the cycle for each step is about 1.0 second.

  7. Relating appendicular skeletal variation of sigmodontine rodents to locomotion modes in a phylogenetic context.

    Science.gov (United States)

    Carvalho Coutinho, Ludmilla; Alves de Oliveira, João

    2017-10-01

    Sigmodontinae rodents constitute the second-largest subfamily among mammals. Alongside the taxonomic diversity, they are also ecologically diverse, exhibiting a wide array of locomotion modes, with semifossorial, terrestrial, semiaquatic, scansorial, arboreal, and saltatorial forms. To understand the ecomorphologic aspects that allow these rodents to display such locomotion diversity, we analyzed 35 qualitative characters of the appendicular skeleton (humerus, ulna, radius, scapula, femur, tibia, ilium, ischium and pubis) in 795 specimens belonging to 64 species, 34 genera and 10 tribes, representing all locomotion modes assigned to this subfamily. We performed a statistical analysis based upon the coefficient of trait differentiation to test the congruence of character states and the different locomotion modes. We also mapped characters states in a molecular phylogeny in order to reconstruct ancestral states and to evaluate how appendicular characters evolved within main lineages of Sigmodontinae radiation under a phylogenetic framework. The statistical analyses revealed six characters related to specific locomotion modes, except terrestrial. The mapping and parsimony ancestral states reconstruction identified two characters with phylogenetical signal and eight characters that are exclusively or more frequently recorded in certain modes of locomotion, four of them also detected by the statistical analysis. Notwithstanding the documented morphological variation, few changes characterize the transition to each of the locomotion modes, at least regarding the appendicular skeleton. This finding corroborates previous results that showed that sigmodontines exhibit an all-purpose appendicular morphology that allows them to use and explore a great variety of habitats. © 2017 Anatomical Society.

  8. Trunk orientation causes asymmetries in leg function in small bird terrestrial locomotion.

    Science.gov (United States)

    Andrada, Emanuel; Rode, Christian; Sutedja, Yefta; Nyakatura, John A; Blickhan, Reinhard

    2014-12-22

    In contrast to the upright trunk in humans, trunk orientation in most birds is almost horizontal (pronograde). It is conceivable that the orientation of the heavy trunk strongly influences the dynamics of bipedal terrestrial locomotion. Here, we analyse for the first time the effects of a pronograde trunk orientation on leg function and stability during bipedal locomotion. For this, we first inferred the leg function and trunk control strategy applied by a generalized small bird during terrestrial locomotion by analysing synchronously recorded kinematic (three-dimensional X-ray videography) and kinetic (three-dimensional force measurement) quail locomotion data. Then, by simulating quail gaits using a simplistic bioinspired numerical model which made use of parameters obtained in in vivo experiments with real quail, we show that the observed asymmetric leg function (left-skewed ground reaction force and longer leg at touchdown than at lift-off) is necessary for pronograde steady-state locomotion. In addition, steady-state locomotion becomes stable for specific morphological parameters. For quail-like parameters, the most common stable solution is grounded running, a gait preferred by quail and most of the other small birds. We hypothesize that stability of bipedal locomotion is a functional demand that, depending on trunk orientation and centre of mass location, constrains basic hind limb morphology and function, such as leg length, leg stiffness and leg damping. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  9. Fossils, feet and the evolution of human bipedal locomotion.

    Science.gov (United States)

    Harcourt-Smith, W E H; Aiello, L C

    2004-05-01

    We review the evolution of human bipedal locomotion with a particular emphasis on the evolution of the foot. We begin in the early twentieth century and focus particularly on hypotheses of an ape-like ancestor for humans and human bipedal locomotion put forward by a succession of Gregory, Keith, Morton and Schultz. We give consideration to Morton's (1935) synthesis of foot evolution, in which he argues that the foot of the common ancestor of modern humans and the African apes would be intermediate between the foot of Pan and Hylobates whereas the foot of a hypothetical early hominin would be intermediate between that of a gorilla and a modern human. From this base rooted in comparative anatomy of living primates we trace changing ideas about the evolution of human bipedalism as increasing amounts of postcranial fossil material were discovered. Attention is given to the work of John Napier and John Robinson who were pioneers in the interpretation of Plio-Pleistocene hominin skeletons in the 1960s. This is the period when the wealth of evidence from the southern African australopithecine sites was beginning to be appreciated and Olduvai Gorge was revealing its first evidence for Homo habilis. In more recent years, the discovery of the Laetoli footprint trail, the AL 288-1 (A. afarensis) skeleton, the wealth of postcranial material from Koobi Fora, the Nariokotome Homo ergaster skeleton, Little Foot (Stw 573) from Sterkfontein in South Africa, and more recently tantalizing material assigned to the new and very early taxa Orrorin tugenensis, Ardipithecus ramidus and Sahelanthropus tchadensis has fuelled debate and speculation. The varying interpretations based on this material, together with changing theoretical insights and analytical approaches, is discussed and assessed in the context of new three-dimensional morphometric analyses of australopithecine and Homo foot bones, suggesting that there may have been greater diversity in human bipedalism in the earlier phases

  10. Natural Translating Locomotion Modulates Cortical Activity at Action Observation

    Directory of Open Access Journals (Sweden)

    Thierry Pozzo

    2017-11-01

    Full Text Available The present study verified if the translational component of locomotion modulated cortical activity recorded at action observation. Previous studies focusing on visual processing of biological motion mainly presented point light walker that were fixed on a spot, thus removing the net translation toward a goal that yet remains a critical feature of locomotor behavior. We hypothesized that if biological motion recognition relies on the transformation of seeing in doing and its expected sensory consequences, a significant effect of translation compared to centered displays on sensorimotor cortical activity is expected. To this aim, we explored whether EEG activity in the theta (4–8 Hz, alpha (8–12 Hz, beta 1 (14–20 Hz and beta 2 (20–32 Hz frequency bands exhibited selectivity as participants viewed four types of stimuli: a centered walker, a centered scrambled, a translating walker and a translating scrambled. We found higher theta synchronizations for observed stimulus with familiar shape. Higher power decreases in the beta 1 and beta 2 bands, indicating a stronger motor resonance was elicited by translating compared to centered stimuli. Finally, beta bands modulation in Superior Parietal areas showed that the translational component of locomotion induced greater motor resonance than human shape. Using a Multinomial Logistic Regression classifier we found that Dorsal-Parietal and Inferior-Frontal regions of interest (ROIs, constituting the core of action-observation system, were the only areas capable to discriminate all the four conditions, as reflected by beta activities. Our findings suggest that the embodiment elicited by an observed scenario is strongly mediated by horizontal body displacement.

  11. Undulatory locomotion of finite filaments: lessons from Caenorhabditis elegans

    International Nuclear Information System (INIS)

    Berman, R S; Kenneth, O; Sznitman, J; Leshansky, A M

    2013-01-01

    Undulatory swimming is a widespread propulsion strategy adopted by many small-scale organisms including various single-cell eukaryotes and nematodes. In this work, we report a comprehensive study of undulatory locomotion of a finite filament using (i) approximate resistive force theory (RFT) assuming a local nature of hydrodynamic interaction between the filament and the surrounding viscous liquid and (ii) particle-based numerical computations taking into account the intra-filament hydrodynamic interaction. Using the ubiquitous model of a propagating sinusoidal waveform, we identify the limit of applicability of the RFT and determine the optimal propulsion gait in terms of (i) swimming distance per period of undulation and (ii) hydrodynamic propulsion efficiency. The occurrence of the optimal swimming gait maximizing hydrodynamic efficiency at finite wavelength in particle-based computations diverges from the prediction of the RFT. To compare the model swimmer powered by sine wave undulations to biological undulatory swimmers, we apply the particle-based approach to study locomotion of the model organism nematode Caenorhabditis elegans using the swimming gait extracted from experiments. The analysis reveals that even though the amplitude and the wavenumber of undulations are similar to those determined for the best performing sinusoidal swimmer, C. elegans overperforms the latter in terms of both displacement and hydrodynamic efficiency. Further comparison with other undulatory microorganisms reveals that many adopt waveforms with characteristics similar to the optimal model swimmer, yet real swimmers still manage to beat the best performing sine-wave swimmer in terms of distance covered per period. Overall our results underline the importance of further waveform optimization, as periodic undulations adopted by C. elegans and other organisms deviate considerably from a simple sine wave. (paper)

  12. Adaptive Gaze Strategies for Locomotion with Constricted Visual Field

    Directory of Open Access Journals (Sweden)

    Colas N. Authié

    2017-07-01

    Full Text Available In retinitis pigmentosa (RP, loss of peripheral visual field accounts for most difficulties encountered in visuo-motor coordination during locomotion. The purpose of this study was to accurately assess the impact of peripheral visual field loss on gaze strategies during locomotion, and identify compensatory mechanisms. Nine RP subjects presenting a central visual field limited to 10–25° in diameter, and nine healthy subjects were asked to walk in one of three directions—straight ahead to a visual target, leftward and rightward through a door frame, with or without obstacle on the way. Whole body kinematics were recorded by motion capture, and gaze direction in space was reconstructed using an eye-tracker. Changes in gaze strategies were identified in RP subjects, including extensive exploration prior to walking, frequent fixations of the ground (even knowing no obstacle was present, of door edges, essentially of the proximal one, of obstacle edge/corner, and alternating door edges fixations when approaching the door. This was associated with more frequent, sometimes larger rapid-eye-movements, larger movements, and forward tilting of the head. Despite the visual handicap, the trajectory geometry was identical between groups, with a small decrease in walking speed in RPs. These findings identify the adaptive changes in sensory-motor coordination, in order to ensure visual awareness of the surrounding, detect changes in spatial configuration, collect information for self-motion, update the postural reference frame, and update egocentric distances to environmental objects. They are of crucial importance for the design of optimized rehabilitation procedures.

  13. Visual control of trunk translation and orientation during locomotion.

    Science.gov (United States)

    Anson, E; Agada, P; Kiemel, T; Ivanenko, Y; Lacquaniti, F; Jeka, J

    2014-06-01

    Previous studies have suggested distinct control of gait characteristics in the anterior-posterior (AP) and medial-lateral (ML) directions in response to visual input. Responses were larger to a ML visual stimulus, suggesting that vision plays a larger role in stabilizing gait in the ML direction. Here, we investigated responses of the trunk during locomotion to determine whether a similar direction dependence is observed. We hypothesized that translation of the trunk would show a similar ML dependence on vision, but that angular deviations of the trunk would show equivalent responses in all directions. Subjects stood or walked on a treadmill at 5 km/h while viewing a virtual wall of white triangles that moved in either the AP or ML direction according to a broadband input stimulus. Frequency response functions between the visual scene motion and trunk kinematics revealed that trunk translation gain was larger across all frequencies during walking compared with standing. Trunk orientation responses were not different from standing at very low frequencies; however, at high frequencies, trunk orientation gain was much higher during walking. Larger gains in response to ML visual scene motion were found for all trunk movements. Higher gains in the ML direction while walking suggest that visual feedback may contribute more to the stability of trunk movements in the ML direction. Vision modified trunk movement behavior on both a slow (translation) and fast (orientation) time scale suggesting a priority for minimizing angular deviations of the trunk. Overall, trunk responses to visual input were consistent with the theme that control of locomotion requires higher-level sensory input to maintain stability in the ML direction.

  14. Wavelength conversion in optical packet switching

    DEFF Research Database (Denmark)

    Danielsen, Søren Lykke; Hansen, Peter Bukhave; Stubkjær, Kristian

    1998-01-01

    A detailed traffic analysis of optical packet switch design is performed. Special consideration is given to the complexity of the optical buffering and the overall switch block structure is considered in general. Wavelength converters are shown to improve the traffic performance of the switch...... blocks for both random and bursty traffic. Furthermore, the traffic performance of switch blocks with add-drop switches has been assessed in a Shufflenetwork showing the advantage of having converters at the inlets. Finally, the aspect of synchronization is discussed through a proposal to operate...... the packet switch block asynchronously, i.e. without packet alignment at the input...

  15. Switching in electrical transmission and distribution systems

    CERN Document Server

    Smeets, René; Kapetanovic, Mirsad; Peelo, David F; Janssen, Anton

    2014-01-01

    Switching in Electrical Transmission and Distribution Systems presents the issues and technological solutions associated with switching in power systems, from medium to ultra-high voltage. The book systematically discusses the electrical aspects of switching, details the way load and fault currents are interrupted, the impact of fault currents, and compares switching equipment in particular circuit-breakers. The authors also explain all examples of practical switching phenomena by examining real measurements from switching tests. Other highlights include: up to date commentary on new develo

  16. Measurement of black carbon emissions from in-use diesel-electric passenger locomotives in California

    Science.gov (United States)

    Tang, N. W.; Kirchstetter, T.; Martien, P. T.; Apte, J.

    2015-12-01

    Black carbon (BC) emission factors were measured for a California commuter rail line fleet of diesel-electric passenger locomotives (Caltrain). The emission factors are based on BC and carbon dioxide (CO2) concentrations in the exhaust plumes of passing locomotives, which were measured from pedestrian overpasses using portable analyzers. Each of the 29 locomotives in the fleet was sampled on 4-20 separate occasions at different locations to characterize different driving modes. The average emission factor expressed as g BC emitted per kg diesel consumed was 0.87 ± 0.66 g kg-1 (±1 standard deviation, n = 362 samples). BC emission factors tended to be higher for accelerating locomotives traveling at higher speeds with engines in higher notch settings. Higher fuel-based BC emission factors (g kg-1) were measured for locomotives equipped with separate "head-end" power generators (SEP-HEPs), which power the passenger cars, while higher time-based emission factors (g h-1) were measured for locomotives without SEP-HEPs, whose engines are continuously operated at high speeds to provide both head-end and propulsion power. PM10 emission factors, estimated assuming a BC/PM10 emission ratio of 0.6 and a typical power output-to-fuel consumption ratio, were generally in line with the Environmental Protection Agency's locomotive exhaust emission standards. Per passenger mile, diesel-electric locomotives in this study emit only 20% of the CO2 emitted by typical gasoline-powered light-duty vehicles (i.e., cars). However, the reduction in carbon footprint (expressed in terms of CO2 equivalents) due to CO2 emissions avoidance from a passenger commuting by train rather than car is appreciably offset by the locomotive's higher BC emissions.

  17. [The significance of exercises and sports in the locomotive syndrome prevention.

    Science.gov (United States)

    Ishibashi, Hideaki

    In Japan, the world's fastest aging country, the locomotive syndrome that shows a decrease in the mobility due to dysfunctions of the locomotor organs is a major risk factor of long-term care need in the old age. Exercises and sports habits are well reviewed to lead to the improvement and maintenance of motor function, and exercises are also useful in the prevention of a number of musculoskeletal diseases. In addition, several trials with the exercise intervention indicated improvement in motor function, suggesting exercises could prevent the locomotive syndrome. In future, prevalence of exercise habits may lead to decrease the prevalence of locomotive syndrome, resulting in elongation of the healthy life span.

  18. Salicylic acid-dependent gene expression is activated by locomotion mucus of different molluscan herbivores.

    Science.gov (United States)

    Meldau, Stefan; Kästner, Julia; von Knorre, Dietrich; Baldwin, Ian T

    2014-01-01

    Slugs and snails specifically secrete mucus to aid their locomotion. This mucus is the contact material between molluscan herbivores and plants. We have recently shown that the locomotion mucus of the slug Deroceras reticulatum contains salicylic acid (SA).(1) When applied to wounded leaves of Arabidopsis thaliana this mucus induces the activity of the SA-responsive pathogenesis related 1 (PR1) promotor1. Here we analyzed PR1 promotor activity in response to treatments with locomotion mucus of eight slugs and snails. Although none of the mucus contained SA, their application still elicited PR1 promotor activity. These data provide further insights into the complex interactions between molluscan herbivores and plants.

  19. A survey report for the design of biped locomotion robot: the WL-12 (Waseda Leg-12)

    Energy Technology Data Exchange (ETDEWEB)

    Takanishi, Atsuo; Kato, Ichiro [Waseda Univ., Tokyo (Japan); Kume, Etsuo

    1991-11-01

    A mechanical design study of biped locomotion robots is going on at JAERI within the scope of the Human Acts Simulation Program (HASP). The design study at JAERI is of an arbitrarily mobile robot for inspection of nuclear facilities. A survey has been performed for collecting useful information from already existing biped locomotion robots. This is a survey report of the biped locomotion robot: the WL-12 designed and developed at Waseda University. This report includes the mechanical model and control system designs. (author).

  20. Multiuser switched diversity scheduling schemes

    KAUST Repository

    Shaqfeh, Mohammad

    2012-09-01

    Multiuser switched-diversity scheduling schemes were recently proposed in order to overcome the heavy feedback requirements of conventional opportunistic scheduling schemes by applying a threshold-based, distributed, and ordered scheduling mechanism. The main idea behind these schemes is that slight reduction in the prospected multiuser diversity gains is an acceptable trade-off for great savings in terms of required channel-state-information feedback messages. In this work, we characterize the achievable rate region of multiuser switched diversity systems and compare it with the rate region of full feedback multiuser diversity systems. We propose also a novel proportional fair multiuser switched-based scheduling scheme and we demonstrate that it can be optimized using a practical and distributed method to obtain the feedback thresholds. We finally demonstrate by numerical examples that switched-diversity scheduling schemes operate within 0.3 bits/sec/Hz from the ultimate network capacity of full feedback systems in Rayleigh fading conditions. © 2012 IEEE.

  1. Soliton switching in directional couplers

    NARCIS (Netherlands)

    Valkering, T.P.; Hoekstra, Hugo; de Boer, Pieter-Tjerk

    1999-01-01

    The mechanism of pulse switching is investigated analytically and numerically for a family of initial conditions with a solitonlike pulse in one channel and no signal on the other channel of the coupler. This investigation is performed directly in the coupled nonlinear Schroedinger equations that

  2. Intrinsic nanofilamentation in resistive switching

    KAUST Repository

    Wu, Xing

    2013-03-15

    Resistive switching materials are promising candidates for nonvolatile data storage and reconfiguration of electronic applications. Intensive studies have been carried out on sandwiched metal-insulator-metal structures to achieve high density on-chip circuitry and non-volatile memory storage. Here, we provide insight into the mechanisms that govern highly reproducible controlled resistive switching via a nanofilament by using an asymmetric metal-insulator-semiconductor structure. In-situ transmission electron microscopy is used to study in real-time the physical structure and analyze the chemical composition of the nanofilament dynamically during resistive switching. Electrical stressing using an external voltage was applied by a tungsten tip to the nanosized devices having hafnium oxide (HfO2) as the insulator layer. The formation and rupture of the nanofilaments result in up to three orders of magnitude change in the current flowing through the dielectric during the switching event. Oxygen vacancies and metal atoms from the anode constitute the chemistry of the nanofilament.

  3. Switching Costs in Accounting Services

    Directory of Open Access Journals (Sweden)

    Fatih Koç

    2015-06-01

    Full Text Available Switching cost is defined as possible costs that customers may encounter when they want to change the firm they buy service, and an important subject in terms of accounting services. Particularly, small business entrepreneurs’ not having knowledge about accounting procedures, and sharing private information with accounting firms make switching costs more important for accounting services. Thus, the aim of this study is to investigate the concept of switching costs (relational cost, procedural cost and financial cost, its determinants (perceived service quality, service importance, and service failures, and consequences (re-purchasing, and recommen ding to others. Theresearch was conducted on small business entrepreneurs in down-town of Balıkesir in Turkey. Total 405 small business entrepreneur owners were interviewed. According to results of the study, perceived service quality positively affects all dimensions of switching costs, significance of service positively affects procedural and relational costs, and service failures negatively affect procedural and relational costs. The results showed that while procedural and relational costs positively affect re-purchasing and recommending to others variables, financial cost did not have any effect on these variables.

  4. Nanoscale organic ferroelectric resistive switches

    NARCIS (Netherlands)

    Khikhlovskyi, V.; Wang, R.; Breemen, A.J.J.M. van; Gelinck, G.H.; Janssen, R.A.J.; Kemerink, M.

    2014-01-01

    Organic ferroelectric resistive switches function by grace of nanoscale phase separation in a blend of a semiconducting and a ferroelectric polymer that is sandwiched between metallic electrodes. In this work, various scanning probe techniques are combined with numerical modeling to unravel their

  5. Switching processes in financial markets.

    Science.gov (United States)

    Preis, Tobias; Schneider, Johannes J; Stanley, H Eugene

    2011-05-10

    For an intriguing variety of switching processes in nature, the underlying complex system abruptly changes from one state to another in a highly discontinuous fashion. Financial market fluctuations are characterized by many abrupt switchings creating upward trends and downward trends, on time scales ranging from macroscopic trends persisting for hundreds of days to microscopic trends persisting for a few minutes. The question arises whether these ubiquitous switching processes have quantifiable features independent of the time horizon studied. We find striking scale-free behavior of the transaction volume after each switching. Our findings can be interpreted as being consistent with time-dependent collective behavior of financial market participants. We test the possible universality of our result by performing a parallel analysis of fluctuations in time intervals between transactions. We suggest that the well known catastrophic bubbles that occur on large time scales--such as the most recent financial crisis--may not be outliers but single dramatic representatives caused by the formation of increasing and decreasing trends on time scales varying over nine orders of magnitude from very large down to very small.

  6. Wide Bandgap Extrinsic Photoconductive Switches

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, James S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2013-07-03

    Semi-insulating Gallium Nitride, 4H and 6H Silicon Carbide are attractive materials for compact, high voltage, extrinsic, photoconductive switches due to their wide bandgap, high dark resistance, high critical electric field strength and high electron saturation velocity. These wide bandgap semiconductors are made semi-insulating by the addition of vanadium (4H and 6HSiC) and iron (2H-GaN) impurities that form deep acceptors. These deep acceptors trap electrons donated from shallow donor impurities. The electrons can be optically excited from these deep acceptor levels into the conduction band to transition the wide bandgap semiconductor materials from a semi-insulating to a conducting state. Extrinsic photoconductive switches with opposing electrodes have been constructed using vanadium compensated 6H-SiC and iron compensated 2H-GaN. These extrinsic photoconductive switches were tested at high voltage and high power to determine if they could be successfully used as the closing switch in compact medical accelerators.

  7. Androgenic switch in barley microspores

    NARCIS (Netherlands)

    de Faria Maraschin, Simone

    2005-01-01

    Barley androgenesis represents an attractive system to study stress-induced cell differentiation and is a valuable tool for efficient plant breeding. The switch from the pollen developmental pathway towards an androgenic route involves several well-described morphological changes. However, little is

  8. Microstrip PIN diode microwave switch

    OpenAIRE

    Usanov, Dmitry A.; Skripal, A. V.; Kulikov, M. Yu.

    2011-01-01

    A possibility of creating narrow-band electrically controlled microwave breakers and switches with enhanced attenuation level in the blocking mode has been considered. The specified devices are based on the structure containing a short-circuited microstrip link with connected capacitor and the loop coupler, in the center of which is located a PIN diode.

  9. Incorrect predictions reduce switch costs.

    Science.gov (United States)

    Kleinsorge, Thomas; Scheil, Juliane

    2015-07-01

    In three experiments, we combined two sources of conflict within a modified task-switching procedure. The first source of conflict was the one inherent in any task switching situation, namely the conflict between a task set activated by the recent performance of another task and the task set needed to perform the actually relevant task. The second source of conflict was induced by requiring participants to guess aspects of the upcoming task (Exps. 1 & 2: task identity; Exp. 3: position of task precue). In case of an incorrect guess, a conflict accrues between the representation of the guessed task and the actually relevant task. In Experiments 1 and 2, incorrect guesses led to an overall increase of reaction times and error rates, but they reduced task switch costs compared to conditions in which participants predicted the correct task. In Experiment 3, incorrect guesses resulted in faster performance overall and to a selective decrease of reaction times in task switch trials when the cue-target interval was long. We interpret these findings in terms of an enhanced level of controlled processing induced by a combination of two sources of conflict converging upon the same target of cognitive control. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. The Atlas load protection switch

    CERN Document Server

    Davis, H A; Dorr, G; Martínez, M; Gribble, R F; Nielsen, K E; Pierce, D; Parsons, W M

    1999-01-01

    Atlas is a high-energy pulsed-power facility under development to study materials properties and hydrodynamics experiments under extreme conditions. Atlas will implode heavy liner loads (m~45 gm) with a peak current of 27-32 MA delivered in 4 mu s, and is energized by 96, 240 kV Marx generators storing a total of 23 MJ. A key design requirement for Atlas is obtaining useful data for 95601130f all loads installed on the machine. Materials response calculations show current from a prefire can damage the load requiring expensive and time consuming replacement. Therefore, we have incorporated a set of fast-acting mechanical switches in the Atlas design to reduce the probability of a prefire damaging the load. These switches, referred to as the load protection switches, short the load through a very low inductance path during system charge. Once the capacitors have reached full charge, the switches open on a time scale short compared to the bank charge time, allowing current to flow to the load when the trigger pu...

  11. The New Era of Virtual Reality Locomotion: A Systematic Literature Review of Techniques and a Proposed Typology

    Directory of Open Access Journals (Sweden)

    Costas Boletsis

    2017-09-01

    Full Text Available The latest technical and interaction advancements that took place in the Virtual Reality (VR field have marked a new era, not only for VR, but also for VR locomotion. Although the latest advancements in VR locomotion have raised the interest of both researchers and users in analyzing and experiencing current VR locomotion techniques, the field of research on VR locomotion, in its new era, is still uncharted. In this work, VR locomotion is explored through a systematic literature review investigating empirical studies of VR locomotion techniques from 2014–2017. The review analyzes the VR locomotion techniques that have been studied, their interaction-related characteristics and the research topics that were addressed in these studies. Thirty-six articles were identified as relevant to the literature review, and the analysis of the articles resulted in 73 instances of 11 VR locomotion techniques, such as real-walking, walking-in-place, point and teleport, joystick-based locomotion, and more. Results showed that since the VR revival, the focus of VR locomotion research has been on VR technology and various technological aspects, overshadowing the investigation of user experience. From an interaction perspective, the majority of the utilized and studied VR locomotion techniques were found to be based on physical interaction, exploiting physical motion cues for navigation in VR environments. A significant contribution of the literature review lies in the proposed typology for VR locomotion, introducing four distinct VR locomotion types: motion-based, room scale-based, controller-based and teleportation-based locomotion.

  12. Switch-connected HyperX network

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Dong; Heidelberger, Philip

    2018-02-13

    A network system includes a plurality of sub-network planes and global switches. The sub-network planes have a same network topology as each other. Each of the sub-network planes includes edge switches. Each of the edge switches has N ports. Each of the global switches is configured to connect a group of edge switches at a same location in the sub-network planes. In each of the sub-network planes, some of the N ports of each of the edge switches are connected to end nodes, and others of the N ports are connected to other edge switches in the same sub-network plane, other of the N ports are connected to at least one of the global switches.

  13. Wide Bandgap Extrinsic Photoconductive Switches

    Science.gov (United States)

    Sullivan, James Stephen

    Wide Bandgap Extrinsic Photoconductive Switches Semi-insulating Gallium Nitride, 4H and 6H Silicon Carbide are attractive materials for compact, high voltage, extrinsic, photoconductive switches due to their wide bandgap, high dark resistance, high critical electric field strength and high electron saturation velocity. These wide bandgap semiconductors are made semi-insulating by the addition of vanadium (4H and 6H-SiC) and iron (2H-GaN) impurities that form deep acceptors. These deep acceptors trap electrons donated from shallow donor impurities. The electrons can be optically excited from these deep acceptor levels into the conduction band to transition the wide bandgap semiconductor materials from a semi-insulating to a conducting state. Extrinsic photoconductive switches with opposing electrodes have been constructed using vanadium compensated 6H-SiC and iron compensated 2H-GaN. These extrinsic photoconductive switches were tested at high voltage and high power to determine if they could be successfully used as the closing switch in compact medical accelerators. The successful development of a vanadium compensated, 6H-SiC extrinsic photoconductive switch for use as a closing switch for compact accelerator applications was realized by improvements made to the vanadium, nitrogen and boron impurity densities. The changes made to the impurity densities were based on the physical intuition outlined and simple rate equation models. The final 6H-SiC impurity 'recipe' calls for vanadium, nitrogen and boron densities of 2.5 e17 cm-3, 1.25e17 cm-3 and ≤ 1e16 cm-3, respectively. This recipe was originally developed to maximize the quantum efficiency of the vanadium compensated 6H-SiC, while maintaining a thermally stable semi-insulating material. The rate equation models indicate that, besides increasing the quantum efficiency, the impurity recipe should be expected to also increase the carrier recombination time. Three generations of 6H-SiC materials were tested. The

  14. 49 CFR 236.822 - Switch, spring.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Switch, spring. 236.822 Section 236.822... Switch, spring. A switch equipped with a spring device which forces the points to their original position after being trailed through and holds them under spring compression. ...

  15. A gain-coefficient switched Alexandrite laser

    International Nuclear Information System (INIS)

    Lee, Chris J; Van der Slot, Peter J M; Boller, Klaus-J

    2013-01-01

    We report on a gain-coefficient switched Alexandrite laser. An electro-optic modulator is used to switch between high and low gain states by making use of the polarization dependent gain of Alexandrite. In gain-coefficient switched mode, the laser produces 85 ns pulses with a pulse energy of 240 mJ at a repetition rate of 5 Hz.

  16. Bootstrapped Low-Voltage Analog Switches

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper

    1999-01-01

    Novel low-voltage constant-impedance analog switch circuits are proposed. The switch element is a single MOSFET, and constant-impedance operation is obtained using simple circuits to adjust the gate and bulk voltages relative to the switched signal. Low-voltage (1-volt) operation is made feasible...

  17. A CW Gunn diode bistable switching element.

    Science.gov (United States)

    Hurtado, M.; Rosenbaum, F. J.

    1972-01-01

    Experiments with a current-controlled bistable switching element using a CW Gunn diode are reported. Switching rates of the order of 10 MHz have been obtained. Switching is initiated by current pulses of short duration (5-10 ns). Rise times of the order of several nanoseconds could be obtained.

  18. Caffeine improves anticipatory processes in task switching

    NARCIS (Netherlands)

    Tieges, Zoe; Snel, Jan; Kok, Albert; Wijnen, Jasper G.; Lorist, Monicque M.; Ridderinkhof, K. Richard

    We studied the effects of moderate amounts of caffeine on task switching and task maintenance using mixed-task (AABB) blocks, in which participants alternated predictably between two tasks, and single-task (AAAA, BBBB) blocks. Switch costs refer to longer reaction times (RT) on task switch trials

  19. Switching antidepressants | Outhoff | South African Family Practice

    African Journals Online (AJOL)

    ... worsening depression or unpleasant discontinuation reactions. Switching strategies to minimise these risks include immediate switching, cross-tapering or incorporating a washout period. Immediate switching is generally possible when substituting a selective serotonin reuptake inhibitor or a serotonin and noradrenaline ...

  20. 47 CFR 69.106 - Local switching.

    Science.gov (United States)

    2010-10-01

    ... foreign services that use local exchange switching facilities. (c) If end users of an interstate or... local exchange carriers shall establish rate elements for local switching as follows: (1) Price cap... use local exchange switching facilities for the provision of interstate or foreign services. The...

  1. LSTM-Based Temperature Prediction for Hot-Axles of Locomotives

    Directory of Open Access Journals (Sweden)

    Luo Can

    2017-01-01

    Full Text Available The reliability of locomotives plays a central role for the smooth operation of railway systems. Hot-axle failures are one of the most commonly found problems leading to locomotive accidents. Since the operating status of the locomotive axle bearings can be distinctly reflected by the axle temperatures, online temperature monitoring has become an essential way to detect hot-axle failures. In this work, we explore the feasibility of predict the hot-axle failures by identifying the temperature from predicted nominal values. We propose a data-driven approach based on the Long Short-Term Memory (LSTM network to predict the sensor temperature for axle bearings. The effectiveness of the prediction model was validated with operation data collected from commercial locomotives. With a prediction accuracy is within a few percent, the proposed techniques can be used as a dynamic reference for hot-axle monitoring.

  2. Kinematics and the Implementation of a Modular Caterpillar Robot in Trapezoidal Wave Locomotion

    Directory of Open Access Journals (Sweden)

    Hongxing Wei

    2013-08-01

    Full Text Available With the development of bionic engineering, research into bionic robots has become a popular topic. In this field, the design of robotic mechanisms to realize the locomotion of insects forms a significant research branch. The current paper presents a caterpillar robotic mechanism that is composed of our newly-developed self-assembly modular robots (Sambot. A trapezoidal wave locomotion gait is planned for the caterpillar mechanism and the kinematics equations are established and solved analytically for such locomotion. The variations of the kinematics quantities are illustrated and discussed. The variation of the jump of the angular acceleration indicates that it is better to apply the trapezoidal wave gait to low velocity situations. Finally, the obtained data of the kinematics quantities is used to perform the gait control locomotion experiment and the errors of the experimental data are analysed in depth.

  3. The Effects of Natural Locomotion on Maneuvering Task Performance in Virtual and Real Environments

    National Research Council Canada - National Science Library

    Unguder, Eray

    2001-01-01

    This thesis investigates human performance differences on maneuvering tasks in virtual and real spaces when a natural locomotion technique is used as opposed to an abstraction through a device such as a...

  4. 49 CFR 222.21 - When must a locomotive horn be used?

    Science.gov (United States)

    2010-10-01

    ... or lead cab car shall be sounded when such locomotive or lead cab car is approaching a public highway... equipped with automatic flashing lights and gates and the gates are fully lowered; or (2) There are no...

  5. STRUCTURAL RELIABILITY OF TRACTION INVERTER FOR MULTI-SYSTEM ELECTRIC LOCOMOTIVE WITH ASYNCHRONOUS TRACTION MOTORS

    Directory of Open Access Journals (Sweden)

    A. M. Muha

    2009-04-01

    Full Text Available In the article the structural reliability of different variants of structured schemes of the steady-state converter for traction drive of promising multi-system electric locomotives with asynchronous traction engines is compared.

  6. Physiological aspects of legged terrestrial locomotion the motor and the machine

    CERN Document Server

    Cavagna, Giovanni

    2017-01-01

    This book offers a succinct but comprehensive description of the mechanics of muscle contraction and legged terrestrial locomotion. It describes on the one hand how the fundamental properties of muscle tissue affect the mechanics of locomotion, and on the other, how the mechanics of locomotion modify the mechanism of muscle operation under different conditions. Further, the book reports on the design and results of experiments conducted with two goals. The first was to describe the physiological function of muscle tissue (which may be considered as the “motor”) contracting at a constant length, during shortening, during lengthening, and under a condition that occurs most frequently in the back-and-forth movement of the limbs during locomotion, namely the stretch-shortening cycle of the active muscle. The second objective was to analyze the interaction between the motor and the “machine” (the skeletal lever system) during walking and running in different scenarios with respect to speed, step frequency,...

  7. Locomotive fuel vapor reclamation system field evaluation and cost-benefit analysis : draft final report.

    Science.gov (United States)

    2015-10-21

    This report summarizes the results of the work performed to install a diesel vapor reclamation unit (DVRU) on an SD70 MAC : locomotive of BNSF Railways and its performance evaluation during freight railroad service. One complete DVRU with several : s...

  8. Arousal and locomotion make distinct contributions to cortical activity patterns and visual encoding

    Science.gov (United States)

    Vinck, Martin; Batista-Brito, Renata; Knoblich, Ulf; Cardin, Jessica A.

    2015-01-01

    Spontaneous and sensory-evoked cortical activity is highly state-dependent, yet relatively little is known about transitions between distinct waking states. Patterns of activity in mouse V1 differ dramatically between quiescence and locomotion, but this difference could be explained by either motor feedback or a change in arousal levels. We recorded single cells and local field potentials from area V1 in mice head-fixed on a running wheel and monitored pupil diameter to assay arousal. Using naturally occurring and induced state transitions, we dissociated arousal and locomotion effects in V1. Arousal suppressed spontaneous firing and strongly altered the temporal patterning of population activity. Moreover, heightened arousal increased the signal-to-noise ratio of visual responses and reduced noise correlations. In contrast, increased firing in anticipation of and during movement was attributable to locomotion effects. Our findings suggest complementary roles of arousal and locomotion in promoting functional flexibility in cortical circuits. PMID:25892300

  9. Locomotion concerns with moral usefulness: When liberals endorse binding moral foundations.

    Science.gov (United States)

    Cornwell, James F M; Higgins, E Tory

    2014-01-01

    Moral Foundations Theory has provided a framework for understanding the endorsement of different moral beliefs. Our research investigated whether there are other reasons to endorse moral foundations in addition to epistemic concerns; specifically, the perceived social usefulness of moral foundations. In Study 1, we demonstrate that those showing stronger locomotion concerns for controlling movement tend toward a higher endorsement of binding foundations, and that this effect is stronger among political liberals who otherwise do not typically endorse these foundations. In Study 2, we show that priming participants with assessment concerns (emphasizing truth) rather than locomotion concerns (emphasizing control) reduces the response variance among liberals and also removes the association between locomotion and the binding foundations. In Study 3, we directly ask participants to focus on moral truth versus moral usefulness, with moral truth replicating the Study 2 effect of assessment priming, and moral usefulness replicating the effect of locomotion priming.

  10. IMPROVING OF ENERGY AND OTHER INDICATORS OF RECEIVING AND ACCEPTANCE TESTING OF ELECTRIC LOCOMOTIVES TRACTION MOTORS

    Directory of Open Access Journals (Sweden)

    P. O. Loza

    2009-03-01

    Full Text Available The methods of determination of equivalent load current in tests of electric locomotive traction engines without forced ventilation with use of the results of qualification test of engines of certain types are offered in the article.

  11. Degree of Conversational Code-Switching Enhances Verbal Task Switching in Cantonese-English Bilinguals

    Science.gov (United States)

    Yim, Odilia; Bialystok, Ellen

    2012-01-01

    The study examined individual differences in code-switching to determine the relationship between code-switching frequency and performance in verbal and non-verbal task switching. Seventy-eight Cantonese-English bilinguals completed a semi-structured conversation to quantify natural code-switching, a verbal fluency task requiring language…

  12. DETERMINATION OF FRAME FORCE FOR ELECTRIC LOCOMOTIVE VL80 WHEN MOVING IN THE CURVED TRACK SECTIONS

    Directory of Open Access Journals (Sweden)

    A. Y. Kuzyshyn

    2017-06-01

    Full Text Available Purpose. When locomotives move in curved sections of the railway track, horizontal forces arise, which lead to pressing the ridge of the wheel pair to the railway track. The article is aimed to develop a method for determining the frame force acting on the bogie from the side of body of the locomotive section using the current methodology of calculating the lateral force. It is also aimed to determine the basic parameters that influence the value of the frame force. It is necessary to construct the dependencies of the frame force on the travel time of electric locomotive in the corresponding curve changing these parameters. Methodology. As is known, the electric locomotive is a multimass mechanical system. We will assume that this system consists of seven bodies: a body, two frames of carriages and four wheel sets. To determine the lateral force acting on the rail from the wheelset one need to solve differential equations of motion of locomotive bogie in curves of small radius. Using the equations of kinetostatics for wheelset one should come to determining the frame force acting on the car bogie from the side of body of the locomotive section. The nominal geometric and mass parameters of parts and components of electric locomotive are taken in the calculations. The curve radius, the length of transition curve, the length of circular curve, the longitudinal slope of railway track and other parameters are fixed values. Findings. There were obtained calculated values of the frame force of electric locomotive VL80 acting on the bogie from the side of body of the locomotive section. Based on the obtained results there were built the dependencies of frame force on the travel time of electric locomotive on the corresponding curve when changing the speed and corresponding elevation of the outer rail. Originality. On the basis of the existing methodology for calculating the lateral force it was developed the method for determining the frame force acting

  13. USE OF MICROCONTROLLER FOR MEASURING SHAFT SPEED OF DIESEL LOCOMOTIVE HYDRAULIC TRANSMISSION

    Directory of Open Access Journals (Sweden)

    I. V. Zhukovytskyy

    2016-10-01

    Full Text Available Purpose. The article considers the process of development and improvement of tachometer data collectors for the data-measuring diesel locomotive hydraulic transmission test system, which will give the possibility of obtaining the source data to conduct further studies of the technical condition of diesel locomotive hydraulic transmission. It is supposed to provide a solution to the problem of development and improvement of tachometer data measuring tools of the previously created data-measuring diesel locomotive hydraulic transmission test system, starting out from the possibility of modification of the existing locomotive hydraulic transmission test-bench at the Dnepropetrovsk Diesel Locomotive Repair Plant «Promteplovoz». Methodology. The researchers proposed in the work a method of modifying the existing tachometer sensor of the automated microprocessor system for the locomotive hydraulic transmission test-bench in the conditions of a diesel locomotive repair plant. It is applicable by substantiating the choice of the required tachometer sensor measuring method, as well as by using the necessary hardware and software to accomplish the goal with the ability to integrate into the data-measuring system for diesel locomotive hydraulic transmission testing. Findings. The available equipment of the locomotive hydraulic transmission test-bench allowed for design of the optical type speed sensor based on the existing sensor D-2MMU-2. The factory testing with the use of a sensor prototype resulted in determination of the required and sufficient sampling time for sensor operating microcontroller. Originality. The available equipment of the locomotive hydraulic transmission test-bench allowed for design of the optical type speed sensor based on the existing sensor D-2MMU-2. We developed the operation algorithms for the microcontroller that processes the signals from this sensor. The sensor was factory-tested. According to the data sample obtained

  14. Profile and genetic parameters of dairy cattle locomotion score and lameness across lactation.

    Science.gov (United States)

    Kougioumtzis, A; Valergakis, G E; Oikonomou, G; Arsenos, G; Banos, G

    2014-01-01

    This study investigated the profile of locomotion score and lameness before the first calving and throughout the first (n=237) and second (n=66) lactation of 303 Holstein cows raised on a commercial farm. Weekly heritability estimates of locomotion score and lameness, and their genetic and phenotypic correlations with milk yield, body condition score, BW and reproduction traits were derived. Daughter future locomotion score and lameness predictions from their sires��� breeding values for conformation traits were also calculated. First-lactation cows were monitored weekly from 6 weeks before calving to the end of lactation. Second-lactation cows were monitored weekly throughout lactation. Cows were locomotion scored on a scale from one (sound) to five (severely lame); a score greater than or equal to two defined presence of lameness. Cows��� weekly body condition score and BW was also recorded. These records were matched to corresponding milk yield records, where the latter were 7-day averages on the week of inspection. The total number of repeated records amounted to 12 221. Data were also matched to the farm���s reproduction database, from which five traits were derived. Statistical analyses were based on uni- and bivariate random regression models. The profile analysis showed that locomotion and lameness problems in first lactation were fewer before and immediately after calving, and increased as lactation progressed. The profile of the two traits remained relatively constant across the second lactation. Highest heritability estimates were observed in the weeks before first calving (0.66 for locomotion score and 0.54 for lameness). Statistically significant genetic correlations were found for first lactation weekly locomotion score and lameness with body condition score, ranging from ���0.31 to ���0.65 and from ���0.44 to ���0.76, respectively, suggesting that cows genetically pre-disposed for high body condition score

  15. Kinematics and the Implementation of a Modular Caterpillar Robot in Trapezoidal Wave Locomotion

    OpenAIRE

    Hongxing Wei; Yuanyang Cui; Haiyuan Li; Jindong Tan; Yong Guan; Yong-Dong Li

    2013-01-01

    With the development of bionic engineering, research into bionic robots has become a popular topic. In this field, the design of robotic mechanisms to realize the locomotion of insects forms a significant research branch. The current paper presents a caterpillar robotic mechanism that is composed of our newly-developed self-assembly modular robots (Sambot). A trapezoidal wave locomotion gait is planned for the caterpillar mechanism and the kinematics equations are established and solved analy...

  16. Development of generalized dynamic model of oscillations of cylinder case of diesel engine of locomotive

    Directory of Open Access Journals (Sweden)

    Irina YUTKINA

    2014-03-01

    Full Text Available An engineering method of design, worked out by the authors, is considered in the paper. It allows to carry out design of amplitude-frequency specter and vibration loading of cylinder cases of the diesel engine of locomotive with account of cavitation-erosion damage. Offered method of design of parameters of cavitation-erosion damage may be used in design of new structures of diesel engines of locomotives and systems of cooling.

  17. Inferring Characteristics of Sensorimotor Behavior by Quantifying Dynamics of Animal Locomotion

    Science.gov (United States)

    Leung, KaWai

    Locomotion is one of the most well-studied topics in animal behavioral studies. Many fundamental and clinical research make use of the locomotion of an animal model to explore various aspects in sensorimotor behavior. In the past, most of these studies focused on population average of a specific trait due to limitation of data collection and processing power. With recent advance in computer vision and statistical modeling techniques, it is now possible to track and analyze large amounts of behavioral data. In this thesis, I present two projects that aim to infer the characteristics of sensorimotor behavior by quantifying the dynamics of locomotion of nematode Caenorhabditis elegans and fruit fly Drosophila melanogaster, shedding light on statistical dependence between sensing and behavior. In the first project, I investigate the possibility of inferring noxious sensory information from the behavior of Caenorhabditis elegans. I develop a statistical model to infer the heat stimulus level perceived by individual animals from their stereotyped escape responses after stimulation by an IR laser. The model allows quantification of analgesic-like effects of chemical agents or genetic mutations in the worm. At the same time, the method is able to differentiate perturbations of locomotion behavior that are beyond affecting the sensory system. With this model I propose experimental designs that allows statistically significant identification of analgesic-like effects. In the second project, I investigate the relationship of energy budget and stability of locomotion in determining the walking speed distribution of Drosophila melanogaster during aging. The locomotion stability at different age groups is estimated from video recordings using Floquet theory. I calculate the power consumption of different locomotion speed using a biomechanics model. In conclusion, the power consumption, not stability, predicts the locomotion speed distribution at different ages.

  18. Ergonomics of locomotive design in South African Gold and Platinum mines.

    CSIR Research Space (South Africa)

    Smith, JR

    2002-03-01

    Full Text Available , a practical strategy was devised for the improvement of the current fleet. Aspects covered during the study included: • analysis of the locomotive operator tasks. • identification of the ergonomics aspects and mechanical engineering... to determine reach, posture, field of view and control locations for the operator. • determining the design modifications, which would improve the overall operation of the mine locomotives in South African gold and platinum mines • formu...

  19. Signals from the ventrolateral thalamus to the motor cortex during locomotion

    Science.gov (United States)

    Marlinski, Vladimir; Nilaweera, Wijitha U.; Zelenin, Pavel V.; Sirota, Mikhail G.

    2012-01-01

    The activity of the motor cortex during locomotion is profoundly modulated in the rhythm of strides. The source of modulation is not known. In this study we examined the activity of one of the major sources of afferent input to the motor cortex, the ventrolateral thalamus (VL). Experiments were conducted in chronically implanted cats with an extracellular single-neuron recording technique. VL neurons projecting to the motor cortex were identified by antidromic responses. During locomotion, the activity of 92% of neurons was modulated in the rhythm of strides; 67% of cells discharged one activity burst per stride, a pattern typical for the motor cortex. The characteristics of these discharges in most VL neurons appeared to be well suited to contribute to the locomotion-related activity of the motor cortex. In addition to simple locomotion, we examined VL activity during walking on a horizontal ladder, a task that requires vision for correct foot placement. Upon transition from simple to ladder locomotion, the activity of most VL neurons exhibited the same changes that have been reported for the motor cortex, i.e., an increase in the strength of stride-related modulation and shortening of the discharge duration. Five modes of integration of simple and ladder locomotion-related information were recognized in the VL. We suggest that, in addition to contributing to the locomotion-related activity in the motor cortex during simple locomotion, the VL integrates and transmits signals needed for correct foot placement on a complex terrain to the motor cortex. PMID:21994259

  20. Extensor motoneurone properties are altered immediately before and during fictive locomotion in the adult decerebrate rat.

    Science.gov (United States)

    MacDonell, C W; Power, K E; Chopek, J W; Gardiner, K R; Gardiner, P F

    2015-05-15

    This study examined motoneurone properties during fictive locomotion in the adult rat for the first time. Fictive locomotion was induced via electrical stimulation of the mesencephalic locomotor region in decerebrate adult rats under neuromuscular blockade to compare basic and rhythmic motoneurone properties in antidromically identified extensor motoneurones during: (1) quiescence, before and after fictive locomotion; (2) the 'tonic' period immediately preceding locomotor-like activity, whereby the amplitude of peripheral flexor (peroneal) and extensor (tibial) nerves are increased but alternation has not yet occurred; and (3) locomotor-like episodes. Locomotion was identified by alternating flexor-extensor nerve activity, where the motoneurone either produced membrane oscillations consistent with a locomotor drive potential (LDP) or did not display membrane oscillation during alternating nerve activity. Cells producing LDPs were referred to as such, while those that did not were referred to as 'idle' motoneurones. LDP and idle motoneurones during locomotion had hyperpolarized spike threshold (Vth ; LDP: 3.8 mV; idle: 5.8 mV), decreased rheobase and an increased discharge rate (LDP: 64%; idle: 41%) during triangular ramp current injection even though the frequency-current slope was reduced by 70% and 55%, respectively. Modulation began in the tonic period immediately preceding locomotion, with a hyperpolarized Vth and reduced rheobase. Spike frequency adaptation did not occur in spiking LDPs or firing generated from sinusoidal current injection, but occurred during a sustained current pulse during locomotion. Input conductance showed no change. Results suggest motoneurone modulation occurs across the pool and is not restricted to motoneurones engaged in locomotion. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

  1. Electronic logic to enhance switch reliability in detecting openings and closures of redundant switches

    Science.gov (United States)

    Cooper, James A.

    1986-01-01

    A logic circuit is used to enhance redundant switch reliability. Two or more switches are monitored for logical high or low output. The output for the logic circuit produces a redundant and failsafe representation of the switch outputs. When both switch outputs are high, the output is high. Similarly, when both switch outputs are low, the logic circuit's output is low. When the output states of the two switches do not agree, the circuit resolves the conflict by memorizing the last output state which both switches were simultaneously in and produces the logical complement of this output state. Thus, the logic circuit of the present invention allows the redundant switches to be treated as if they were in parallel when the switches are open and as if they were in series when the switches are closed. A failsafe system having maximum reliability is thereby produced.

  2. Bone-free: soft mechanics for adaptive locomotion.

    Science.gov (United States)

    Trimmer, B A; Lin, Huai-ti

    2014-12-01

    Muscular hydrostats (such as mollusks), and fluid-filled animals (such as annelids), can exploit their constant-volume tissues to transfer forces and displacements in predictable ways, much as articulated animals use hinges and levers. Although larval insects contain pressurized fluids, they also have internal air tubes that are compressible and, as a result, they have more uncontrolled degrees of freedom. Therefore, the mechanisms by which larval insects control their movements are expected to reveal useful strategies for designing soft biomimetic robots. Using caterpillars as a tractable model system, it is now possible to identify the biomechanical and neural strategies for controlling movements in such highly deformable animals. For example, the tobacco hornworm, Manduca sexta, can stiffen its body by increasing muscular tension (and therefore body pressure) but the internal cavity (hemocoel) is not iso-barometric, nor is pressure used to directly control the movements of its limbs. Instead, fluid and tissues flow within the hemocoel and the body is soft and flexible to conform to the substrate. Even the gut contributes to the biomechanics of locomotion; it is decoupled from the movements of the body wall and slides forward within the body cavity at the start of each step. During crawling the body is kept in tension for part of the stride and compressive forces are exerted on the substrate along the axis of the caterpillar, thereby using the environment as a skeleton. The timing of muscular activity suggests that crawling is coordinated by proleg-retractor motoneurons and that the large segmental muscles produce anterograde waves of lifting that do not require precise timing. This strategy produces a robust form of locomotion in which the kinematics changes little with orientation. In different species of caterpillar, the presence of prolegs on particular body segments is related to alternative kinematics such as "inching." This suggests a mechanism for the

  3. Locomotion of inchworm-inspired robot made of smart soft composite (SSC)

    International Nuclear Information System (INIS)

    Wang, Wei; Lee, Jang-Yeob; Rodrigue, Hugo; Song, Sung-Hyuk; Ahn, Sung-Hoon; Chu, Won-Shik

    2014-01-01

    A soft-bodied robot made of smart soft composite with inchworm-inspired locomotion capable of both two-way linear and turning movement has been proposed, developed, and tested. The robot was divided into three functional parts based on the different functions of the inchworm: the body, the back foot, and the front foot. Shape memory alloy wires were embedded longitudinally in a soft polymer to imitate the longitudinal muscle fibers that control the abdominal contractions of the inchworm during locomotion. Each foot of the robot has three segments with different friction coefficients to implement the anchor and sliding movement. Then, utilizing actuation patterns between the body and feet based on the looping gait, the robot achieves a biomimetic inchworm gait. Experiments were conducted to evaluate the robot’s locomotive performance for both linear locomotion and turning movement. Results show that the proposed robot’s stride length was nearly one third of its body length, with a maximum linear speed of 3.6 mm s −1 , a linear locomotion efficiency of 96.4%, a maximum turning capability of 4.3 degrees per stride, and a turning locomotion efficiency of 39.7%. (paper)

  4. Crouching to fit in: the energetic cost of locomotion in tunnels.

    Science.gov (United States)

    Horner, Angela M; Hanna, Jandy B; Biknevicius, Audrone R

    2016-11-01

    Animals that are specialized for a particular habitat or mode of locomotion often demonstrate locomotor efficiency in a focal environment when compared to a generalist species. However, measurements of these focal habitats or behaviors are often difficult or impossible to do in the field. In this study, the energetics and kinematics of simulated tunnel locomotion by two unrelated semi-fossorial mammals, the ferret and degu, were analyzed using open-flow respirometry and digital video. Animals were trained to move inside of normal (unconstrained, overground locomotion) and height-decreased (simulated tunnel, adjusted to tolerance limits for each species) Plexiglas chambers that were mounted flush onto a treadmill. Both absolute and relative tunnel performance differed between the species; ferrets tolerated a tunnel height that forced them to crouch at nearly 25% lower hip height than in an unconstrained condition, whereas degus would not perform on the treadmill past a ∼9% reduction in hip height. Both ferrets and degus exhibited significantly higher metabolic rates and cost of transport (CoT) values when moving in the tunnel condition relative to overground locomotion. When comparing CoT values across small (locomotion, whereas degus were very close to the line of best fit. Although tunnel locomotion requires a more striking change in posture for ferrets, ferrets are more efficient locomotors in both conditions than mammals of similar mass. © 2016. Published by The Company of Biologists Ltd.

  5. The medial preoptic area modulates cocaine-induced locomotion in male rats.

    Science.gov (United States)

    Will, Ryan G; Martz, Julia R; Dominguez, Juan M

    2016-05-15

    Cocaine-induced locomotion is mediated by dopamine in the nucleus accumbens (NAc). Recent evidence indicates that the medial preoptic area (mPOA), a region in the rostral hypothalamus, modulates cocaine-induced dopamine in the NAc. Specifically, rats with lesions of the mPOA experienced a greater increase in dopamine following cocaine administration than rats with sham lesions. Whether the mPOA similarly influences cocaine-induced locomotion is not known. Here we examined whether radiofrequency or neurotoxic lesions of the mPOA in male rats influence changes in locomotion that follow cocaine administration. Locomotion was measured following cocaine administration in male rats with neurotoxic, radiofrequency, or sham lesions of the mPOA. Results indicate that bilateral lesions of the mPOA facilitated cocaine-induced locomotion. This facilitation was independent of lesion type, as increased locomotion was observed with either approach. These findings support a role for the mPOA as an integral region in the processing of cocaine-induced behavioral response, in this case locomotor activity. Published by Elsevier B.V.

  6. The leg stiffnesses animals use may improve the stability of locomotion.

    Science.gov (United States)

    Shen, ZhuoHua; Seipel, Justin

    2015-07-21

    Despite a wide diversity of running animals, their leg stiffness normalized by animal size and weight (a relative leg stiffness) resides in a narrow range between 7 and 27. Here we determine if the stability of locomotion could be a driving factor for the tight distribution of animal leg stiffness. We simulated an established physics-based model (the actuated Spring-Loaded Inverted Pendulum model) of animal running and found that, with the same energetic cost, perturbations to locomotion are optimally corrected when relative leg stiffness is within the biologically observed range. Here we show that the stability of locomotion, in combination with energetic cost, could be a significant factor influencing the nearly universally observed animal relative leg stiffness range. The energetic cost of locomotion has been widely acknowledged as influencing the evolution of physiology and locomotion behaviors. Specifically, its potential importance for relative leg stiffness has been demonstrated. Here, we demonstrate that stability of locomotion may also be a significant factor influencing relative leg stiffness. Published by Elsevier Ltd.

  7. Shape memory thermal conduction switch

    Science.gov (United States)

    Vaidyanathan, Rajan (Inventor); Krishnan, Vinu (Inventor); Notardonato, William U. (Inventor)

    2010-01-01

    A thermal conduction switch includes a thermally-conductive first member having a first thermal contacting structure for securing the first member as a stationary member to a thermally regulated body or a body requiring thermal regulation. A movable thermally-conductive second member has a second thermal contacting surface. A thermally conductive coupler is interposed between the first member and the second member for thermally coupling the first member to the second member. At least one control spring is coupled between the first member and the second member. The control spring includes a NiTiFe comprising shape memory (SM) material that provides a phase change temperature <273 K, a transformation range <40 K, and a hysteresis of <10 K. A bias spring is between the first member and the second member. At the phase change the switch provides a distance change (displacement) between first and second member by at least 1 mm, such as 2 to 4 mm.

  8. Switch for Good Community Program

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, Tabitha [Balfour Beatty Military Housing Management LLC, Newtown Square, PA (United States); Amran, Martha [WattzOn, Inc., Mountain View, CA (United States)

    2013-11-19

    Switch4Good is an energy-savings program that helps residents reduce consumption from behavior changes; it was co-developed by Balfour Beatty Military Housing Management (BB) and WattzOn in Phase I of this grant. The program was offered at 11 Navy bases. Three customer engagement strategies were evaluated, and it was found that Digital Nudges (a combination of monthly consumption statements with frequent messaging via text or email) was most cost-effective. The program was delivered on-time and on-budget, and its success is based on the teamwork of local BB staff and the WattzOn team. The following graphic shows Switch4Good “by the numbers”, e.g. the scale of operations achieved during Phase I.

  9. Negation switching invariant signed graphs

    Directory of Open Access Journals (Sweden)

    Deepa Sinha

    2014-04-01

    Full Text Available A signed graph (or, $sigraph$ in short is a graph G in which each edge x carries a value $\\sigma(x \\in \\{-, +\\}$ called its sign. Given a sigraph S, the negation $\\eta(S$ of the sigraph S is a sigraph obtained from S by reversing the sign of every edge of S. Two sigraphs $S_{1}$ and $S_{2}$ on the same underlying graph are switching equivalent if it is possible to assign signs `+' (`plus' or `-' (`minus' to vertices of $S_{1}$ such that by reversing the sign of each of its edges that has received opposite signs at its ends, one obtains $S_{2}$. In this paper, we characterize sigraphs which are negation switching invariant and also see for what sigraphs, S and $\\eta (S$ are signed isomorphic.

  10. Large aperture optical switching devices

    International Nuclear Information System (INIS)

    Goldhar, J.; Henesian, M.A.

    1983-01-01

    We have developed a new approach to constructing large aperture optical switches for next generation inertial confinement fusion lasers. A transparent plasma electrode formed in low pressure ionized gas acts as a conductive coating to allow the uniform charging of the optical faces of an electro-optic material. In this manner large electric fields can be applied longitudinally to large aperture, high aspect ratio Pockels cells. We propose a four-electrode geometry to create the necessary high conductivity plasma sheets, and have demonstrated fast (less than 10 nsec) switching in a 5x5 cm aperture KD*P Pockels cell with such a design. Detaid modelling of Pockels cell performance with plasma electrodes has been carried out for 15 and 30 cm aperture designs

  11. Resistive Switching Assisted by Noise

    OpenAIRE

    Patterson, G. A.; Fierens, P. I.; Grosz, D. F.

    2013-01-01

    We extend results by Stotland and Di Ventra on the phenomenon of resistive switching aided by noise. We further the analysis of the mechanism underlying the beneficial role of noise and study the EPIR (Electrical Pulse Induced Resistance) ratio dependence with noise power. In the case of internal noise we find an optimal range where the EPIR ratio is both maximized and independent of the preceding resistive state. However, when external noise is considered no beneficial effect is observed.

  12. Switching strategies to optimize search

    Science.gov (United States)

    Shlesinger, Michael F.

    2016-03-01

    Search strategies are explored when the search time is fixed, success is probabilistic and the estimate for success can diminish with time if there is not a successful result. Under the time constraint the problem is to find the optimal time to switch a search strategy or search location. Several variables are taken into account, including cost, gain, rate of success if a target is present and the probability that a target is present.

  13. Molecular wires, switches and memories

    Science.gov (United States)

    Chen, Jia

    Molecular electronics, an emerging field, makes it possible to build individual molecules capable of performing functions identical or analogous to present- day conductors, switches, or memories. These individual molecules, with a nano-meter scale characteristic length, can be designed and chemically synthesized with specific atoms, geometries and charge distribution. This thesis focuses on the design, and measurements of molecular wires, and related strategically engineered structures-molecular switches and memories. The experimental system relies on a thermodynamically driven self-assembling process to attach molecules onto substrate surfaces without intervention from outside. The following topics will be discussed: directed nanoscale manipulation of self-assembled molecules using scanning tunneling microscope; investigation on through-bond transport of nanoscale symmetric metal/conjugated self- assembled monolayers (SAM)/metal junctions, where non- Ohmic thermionic emission was observed to be the dominant process, with isocyanide-Pd contacts showing the lowest thermionic barrier of 0.22 eV; the first realization of robust and large reversible switching behavior in an electronic device that utilizes molecules containing redox centers as the active component, exhibiting negative differential resistance (NDR) and large on-off peak-to-valley ratio (PVR); observation of erasable storage of higher conductivity states in these redox- center containing molecular devices, and demonstration of a two-terminal electronically programmable and erasable molecular memory cell with long bit retention time.

  14. Analytical Performance Evaluation of Different Switch Solutions

    Directory of Open Access Journals (Sweden)

    Francisco Sans

    2013-01-01

    Full Text Available The virtualization of the network access layer has opened new doors in how we perceive networks. With this virtualization of the network, it is possible to transform a regular PC with several network interface cards into a switch. PC-based switches are becoming an alternative to off-the-shelf switches, since they are cheaper. For this reason, it is important to evaluate the performance of PC-based switches. In this paper, we present a performance evaluation of two PC-based switches, using Open vSwitch and LiSA, and compare their performance with an off-the-shelf Cisco switch. The RTT, throughput, and fairness for UDP are measured for both Ethernet and Fast Ethernet technologies. From this research, we can conclude that the Cisco switch presents the best performance, and both PC-based switches have similar performance. Between Open vSwitch and LiSA, Open vSwitch represents a better choice since it has more features and is currently actively developed.

  15. Streamer model for high voltage water switches

    International Nuclear Information System (INIS)

    Sazama, F.J.; Kenyon, V.L. III

    1979-01-01

    An electrical switch model for high voltage water switches has been developed which predicts streamer-switching effects that correlate well with water-switch data from Casino over the past four years and with switch data from recent Aurora/AMP experiments. Preclosure rounding and postclosure resistive damping of pulseforming line voltage waveforms are explained in terms of spatially-extensive, capacitive-coupling of the conducting streamers as they propagate across the gap and in terms of time-dependent streamer resistance and inductance. The arc resistance of the Casino water switch and of a gas switch under test on Casino was determined by computer fit to be 0.5 +- 0.1 ohms and 0.3 +- 0.06 ohms respectively, during the time of peak current in the power pulse. Energy lost in the water switch during the first pulse is 18% of that stored in the pulseforming line while similar energy lost in the gas switch is 11%. The model is described, computer transient analyses are compared with observed water and gas switch data and the results - switch resistance, inductance and energy loss during the primary power pulse - are presented

  16. Synchronization in complex networks with switching topology

    International Nuclear Information System (INIS)

    Wang, Lei; Wang, Qing-guo

    2011-01-01

    This Letter investigates synchronization issues of complex dynamical networks with switching topology. By constructing a common Lyapunov function, we show that local and global synchronization for a linearly coupled network with switching topology can be evaluated by the time average of second smallest eigenvalues corresponding to the Laplacians of switching topology. This result is quite powerful and can be further used to explore various switching cases for complex dynamical networks. Numerical simulations illustrate the effectiveness of the obtained results in the end. -- Highlights: → Synchronization of complex networks with switching topology is investigated. → A common Lyapunov function is established for synchronization of switching network. → The common Lyapunov function is not necessary to monotonically decrease with time. → Synchronization is determined by the second smallest eigenvalue of its Laplacian. → Synchronization criterion can be used to investigate various switching cases.

  17. Pinning Synchronization of Switched Complex Dynamical Networks

    Directory of Open Access Journals (Sweden)

    Liming Du

    2015-01-01

    Full Text Available Network topology and node dynamics play a key role in forming synchronization of complex networks. Unfortunately there is no effective synchronization criterion for pinning synchronization of complex dynamical networks with switching topology. In this paper, pinning synchronization of complex dynamical networks with switching topology is studied. Two basic problems are considered: one is pinning synchronization of switched complex networks under arbitrary switching; the other is pinning synchronization of switched complex networks by design of switching when synchronization cannot achieved by using any individual connection topology alone. For the two problems, common Lyapunov function method and single Lyapunov function method are used respectively, some global synchronization criteria are proposed and the designed switching law is given. Finally, simulation results verify the validity of the results.

  18. Bristle-Bots: a model system for locomotion and swarming

    Science.gov (United States)

    Giomi, Luca; Hawley-Weld, Nico; Mahadevan, L.

    2012-02-01

    The term swarming describes the ability of a group of similarly sized organisms to move coherently in space and time. This behavior is ubiquitous among living systems: it occurs in sub-cellular systems, bacteria, insects, fish, birds, pedestrians and in general in nearly any group of individuals endowed with the ability to move and sense. Here we address the problem of the origin of collective behavior in systems of self-propelled agents whose only social capability is given by aligning contact interactions. Our model system consists of a collection of Bristle-Bots, simple automata made from a toothbrush and the vibrating device of a cellular phone. When Bristle-Bots are confined in a limited space, increasing their number drives a transition from a disordered and uncoordinated motion to an organized collective behavior. This can occur through the formation of a swirling cluster of robots or a collective dynamical arrest, according to the type of locomotion implemented in the single devices. It is possible to move between these two major regimes by adjusting a single construction parameter.

  19. Energy expenditure for thermoregulation and locomotion in emperor penguins.

    Science.gov (United States)

    Pinshow, B; Fedak, M A; Battles, D R; Schmidt-Nielsen, K

    1976-09-01

    During the antarctic winter emperor penguins (Aptenodytes forsteri) spend up to four mo fasting while they breed at rookeries 80 km or more from the sea, huddling close together in the cold. This breeding cycle makes exceptional demands on their energy reserves, and we therefore studied their thermoregulation and locomotion. Rates of metabolism were measured in five birds (mean body mass, 23.37 kg) at ambient temperatures ranging from 25 to -47 degrees C. Between 20 and -10 degrees C the metabolic rate (standard metabolic rate (SMR)) remained neraly constant, about 42.9 W. Below -10 degrees C metabolic rate increased lineraly with decreasing ambient temperature and at -47 degrees C it was 70% above the SMR. Mean thermal conductance below -10 degrees C was 1.57 W m-2 degrees C-1. Metabolic rate during treadmill walking increased linearly with increasing speed. Our data suggest that walking 200 km (from the sea to the rookery and back) requires less than 15% of the energy reserves of a breeding male emperor penguin initially weighing 35 kg. The high energy requirement for thermoregulation (about 85%) would, in the absence of huddling, probably exceed the total energy reserves.

  20. A jump persistent turning walker to model zebrafish locomotion.

    Science.gov (United States)

    Mwaffo, Violet; Anderson, Ross P; Butail, Sachit; Porfiri, Maurizio

    2015-01-06

    Zebrafish are gaining momentum as a laboratory animal species for the investigation of several functional and dysfunctional biological processes. Mathematical models of zebrafish behaviour are expected to considerably aid in the design of hypothesis-driven studies by enabling preliminary in silico tests that can be used to infer possible experimental outcomes without the use of zebrafish. This study is motivated by observations of sudden, drastic changes in zebrafish locomotion in the form of large deviations in turn rate. We demonstrate that such deviations can be captured through a stochastic mean reverting jump diffusion model, a process that is commonly used in financial engineering to describe large changes in the price of an asset. The jump process-based model is validated on trajectory data of adult subjects swimming in a shallow circular tank obtained from an overhead camera. Through statistical comparison of the empirical distribution of the turn rate against theoretical predictions, we demonstrate the feasibility of describing zebrafish as a jump persistent turning walker. The critical role of the jump term is assessed through comparison with a simplified mean reversion diffusion model, which does not allow for describing the heavy-tailed distributions observed in the fish turn rate. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  1. The forward undulatory locomotion of Ceanorhabditis elegans in viscoelastic fluids

    Science.gov (United States)

    Shen, Amy; Ulrich, Xialing

    2013-11-01

    Caenorhabditis elegans is a soil dwelling roundworm that has served as model organisms for studying a multitude of biological and engineering phenomena. We study the undulatory locomotion of nematode in viscoelastic fluids with zero-shear viscosity varying from 0.03-75 Pa .s and relaxation times ranging from 0-350 s. We observe that the averaged normalized wavelength of swimming worm is essentially the same as that in Newtonian fluids. The undulatory frequency f shows the same reduction rate with respect to zero-shear viscosity in viscoelastic fluids as that found in the Newtonian fluids, meaning that the undulatory frequency is mainly controlled by the fluid viscosity. However, the moving speed Vm of the worm shows more distinct dependence on the elasticity of the fluid and exhibits a 4% drop with each 10-fold increase of the Deborah number De, a dimensionless number characterizing the elasticity of a fluid. To estimate the swimming efficiency coefficient and the ratio K =CN /CL of resistive coefficients of the worm in various viscoelastic fluids, we show that whereas it would take the worm around 7 periods to move a body length in a Newtonian fluid, it would take 27 periods to move a body length in a highly viscoelastic fluid.

  2. Modeling posture-dependent leg actuation in sagittal plane locomotion

    International Nuclear Information System (INIS)

    Schmitt, J; Clark, J

    2009-01-01

    The spring loaded inverted pendulum template has been shown to accurately model the steady locomotion dynamics of a variety of running animals, and has served as the inspiration for an entire class of dynamic running robots. While the template models the leg dynamics by an energy-conserving spring, insects and animals have structures that dissipate, store and produce energy during a stance phase. Recent investigations into the spring-like properties of limbs, as well as animal response to drop-step perturbations, suggest that animals use their legs to manage energy storage and dissipation, and that this management is important for gait stability. In this paper, we extend our previous analysis of control of the spring loaded inverted pendulum template via changes in the leg touch-down angle to include energy variations during the stance phase. Energy variations are incorporated through leg actuation that varies the force-free leg length during the stance phase, yet maintains qualitatively correct force and velocity profiles. In contrast to the partially asymptotically stable gaits identified in previous analyses, incorporating energy and leg angle variations in this manner produces complete asymptotic stability. Drop-step perturbation simulations reveal that the control strategy is rather robust, with gaits recovering from drops of up to 30% of the nominal hip height.

  3. Reinforcement learning of periodical gaits in locomotion robots

    Science.gov (United States)

    Svinin, Mikhail; Yamada, Kazuyaki; Ushio, S.; Ueda, Kanji

    1999-08-01

    Emergence of stable gaits in locomotion robots is studied in this paper. A classifier system, implementing an instance- based reinforcement learning scheme, is used for sensory- motor control of an eight-legged mobile robot. Important feature of the classifier system is its ability to work with the continuous sensor space. The robot does not have a prior knowledge of the environment, its own internal model, and the goal coordinates. It is only assumed that the robot can acquire stable gaits by learning how to reach a light source. During the learning process the control system, is self-organized by reinforcement signals. Reaching the light source defines a global reward. Forward motion gets a local reward, while stepping back and falling down get a local punishment. Feasibility of the proposed self-organized system is tested under simulation and experiment. The control actions are specified at the leg level. It is shown that, as learning progresses, the number of the action rules in the classifier systems is stabilized to a certain level, corresponding to the acquired gait patterns.

  4. Markerless 3D motion capture for animal locomotion studies

    Directory of Open Access Journals (Sweden)

    William Irvin Sellers

    2014-06-01

    Full Text Available Obtaining quantitative data describing the movements of animals is an essential step in understanding their locomotor biology. Outside the laboratory, measuring animal locomotion often relies on video-based approaches and analysis is hampered because of difficulties in calibration and often the limited availability of possible camera positions. It is also usually restricted to two dimensions, which is often an undesirable over-simplification given the essentially three-dimensional nature of many locomotor performances. In this paper we demonstrate a fully three-dimensional approach based on 3D photogrammetric reconstruction using multiple, synchronised video cameras. This approach allows full calibration based on the separation of the individual cameras and will work fully automatically with completely unmarked and undisturbed animals. As such it has the potential to revolutionise work carried out on free-ranging animals in sanctuaries and zoological gardens where ad hoc approaches are essential and access within enclosures often severely restricted. The paper demonstrates the effectiveness of video-based 3D photogrammetry with examples from primates and birds, as well as discussing the current limitations of this technique and illustrating the accuracies that can be obtained. All the software required is open source so this can be a very cost effective approach and provides a methodology of obtaining data in situations where other approaches would be completely ineffective.

  5. An Adaptive Classification Strategy for Reliable Locomotion Mode Recognition

    Directory of Open Access Journals (Sweden)

    Ming Liu

    2017-09-01

    Full Text Available Algorithms for locomotion mode recognition (LMR based on surface electromyography and mechanical sensors have recently been developed and could be used for the neural control of powered prosthetic legs. However, the variations in input signals, caused by physical changes at the sensor interface and human physiological changes, may threaten the reliability of these algorithms. This study aimed to investigate the effectiveness of applying adaptive pattern classifiers for LMR. Three adaptive classifiers, i.e., entropy-based adaptation (EBA, LearnIng From Testing data (LIFT, and Transductive Support Vector Machine (TSVM, were compared and offline evaluated using data collected from two able-bodied subjects and one transfemoral amputee. The offline analysis indicated that the adaptive classifier could effectively maintain or restore the performance of the LMR algorithm when gradual signal variations occurred. EBA and LIFT were recommended because of their better performance and higher computational efficiency. Finally, the EBA was implemented for real-time human-in-the-loop prosthesis control. The online evaluation showed that the applied EBA effectively adapted to changes in input signals across sessions and yielded more reliable prosthesis control over time, compared with the LMR without adaptation. The developed novel adaptive strategy may further enhance the reliability of neurally-controlled prosthetic legs.

  6. Characterization of Hop-and-Sink Locomotion of Water Fleas

    Science.gov (United States)

    Skipper, A. N.; Murphy, D. W.; Webster, D. R.

    2017-11-01

    The freshwater crustacean Daphnia magna is a widely studied zooplankton in relation to food webs, predator-prey interactions, and other biological/ecological considerations; however, their locomotion is poorly quantified and understood. These water fleas utilize a hop-and-sink mechanism that consists of making quick, impulsive jumps by beating their antennae to propel themselves forward (roughly 1 body length). The animals then sink for a period, during which they stretch out their antennae to increase drag and thereby reduce their sinking velocity. Time-resolved three-dimensional flow fields surrounding the animals were quantified with a unique infrared tomographic particle image velocimetry (tomo-PIV) system. Three-dimensional kinematics data were also extracted from the image sequences. In the current work, we compared body kinematics and flow disturbance among organisms of size in the range of 1.3 to 2.8 mm. The stroke cycle averaged 150 +/- 20 ms, with each stroke cycle split nearly evenly between power and recovery strokes. The kinematics data collapsed onto a self-similar curve when properly nondimensionalized, and a general trend was shown to exist between the nondimensionalized peak body speed and body length. The fluid flow induced by each antennae consisted of a viscous vortex ring that demonstrated a slow decay in the wake. The viscous dissipation showed no clear dependence on body size, whereas the volume of fluid exceeding 5 mm/s (the speed near the sinking speed of the animal) decayed more slowly with increasing body size.

  7. Electric-Pneumatic Actuator: A New Muscle for Locomotion

    Directory of Open Access Journals (Sweden)

    Maziar Ahmad Sharbafi

    2017-10-01

    Full Text Available A better understanding of how actuator design supports locomotor function may help develop novel and more functional powered assistive devices or robotic legged systems. Legged robots comprise passive parts (e.g., segments, joints and connections which are moved in a coordinated manner by actuators. In this study, we propose a novel concept of a hybrid electric-pneumatic actuator (EPA as an enhanced variable impedance actuator (VIA. EPA is consisted of a pneumatic artificial muscle (PAM and an electric motor (EM. In contrast to other VIAs, the pneumatic artificial muscle (PAM within the EPA provides not only adaptable compliance, but also an additional powerful actuator with muscle-like properties, which can be arranged in different combinations (e.g., in series or parallel to the EM. The novel hybrid actuator shares the advantages of both integrated actuator types combining precise control of EM with compliant energy storage of PAM, which are required for efficient and adjustable locomotion. Experimental and simulation results based on the new dynamic model of PAM support the hypothesis that combination of the two actuators can improve efficiency (energy and peak power and performance, while does not increase control complexity and weight, considerably. Finally, the experiments on EPA adapted bipedal robot (knee joint of the BioBiped3 robot show improved efficiency of the actuator at different frequencies.

  8. Rapid signaling in distinct dopaminergic axons during locomotion and reward

    Science.gov (United States)

    Howe, MW; Dombeck, DA

    2016-01-01

    Summary Dopaminergic projections from the midbrain to striatum are critical for motor control, as their degeneration in Parkinson’s disease results in profound movement deficits. Paradoxically, most recording methods report rapid phasic dopamine signaling (~100ms bursts) to unpredicted rewards, with little evidence for movement-related signaling. The leading model posits that phasic signaling in striatum targeting dopamine neurons drive reward-based learning, while slow variations in firing (tens of seconds to minutes) in these same neurons bias animals towards or away from movement. However, despite widespread acceptance of this model, current methods have provided little evidence to support or refute it. Here, using new optical recording methods, we report the discovery of rapid phasic signaling in striatum-targeting dopaminergic axons that was associated with, and capable of triggering, locomotion in mice. Axons expressing these signals were largely distinct from those signaling during unexpected rewards. These results suggest that dopaminergic neuromodulation can differentially impact motor control and reward learning with sub-second precision and suggest that both precise signal timing and neuronal subtype are important parameters to consider in the treatment of dopamine-related disorders. PMID:27398617

  9. Unified Phase Variables of Relative Degree Two for Human Locomotion.

    Science.gov (United States)

    Villarreal, Dario J; Gregg, Robert D

    2016-08-01

    A starting point to achieve stable locomotion is synchronizing the leg joint kinematics during the gait cycle. Some biped robots parameterize a nonlinear controller (e.g., input-output feedback linearization) whose main objective is to track specific kinematic trajectories as a function of a single mechanical variable (i.e., a phase variable) in order to allow the robot to walk. A phase variable capable of parameterizing the entire gait cycle, the hip phase angle, has been used to control wearable robots and was recently shown to provide a robust representation of the phase of human gait. However, this unified phase variable relies on hip velocity, which is difficult to measure in real-time and prevents the use of derivative corrections in phase-based controllers for wearable robots. One derivative of this phase variable yields accelerations (i.e., the equations of motion), so the system is said to be relative degree-one. This means that there are states of the system that cannot be controlled. The goal of this paper is to offer relative degree-two alternatives to the hip phase angle and examine their robustness for parameterizing human gait.

  10. Photo-induced locomotion of chemo-responsive polymer gels

    Science.gov (United States)

    Dayal, Pratyush; Kuksenok, Olga; Balazs, Anna C.

    2009-03-01

    The need to translate chemical energy into a mechanical response, a characteristic of many biological processes, has motivated the study of stimuli-responsive polymer gels. Recently, it has been shown experimentally that by coupling the mechanical properties of the gel with the Belousov-Zhabotinsky (BZ) reaction it is possible to induce self-sustained oscillations in the gel. One of the means for controlling these chemical oscillations is using light as an external stimulus. To study the effect of light on the mechanical behavior of the gel, we use our recently developed a 3D gel lattice spring model (gLSM) which couples the BZ reaction kinetics to the gel dynamics. In this model, the polymer-solvent interactions were taken into account by adding a coupling term to the Flory-Huggins free energy. By virtue of this coupling term, the swelling---de-swelling behavior of the gel was captured in 3D. In order to include the effect of the polymer on the reaction kinetics, the Oregonator model for the photo-sensitive BZ reaction was also modified. Using gLSM model, we probed the effect of non-uniform light irradiation on the gel dynamics. We were able to manipulate the direction and velocity of locomotion of the gel using light as a control parameter. This ability to control the movement of the gel can be utilized in a variety of applications, ranging from bio-actuators to controlled drug release systems.

  11. Modeling posture-dependent leg actuation in sagittal plane locomotion

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, J [Department of Mechanical Engineering, Oregon State University, Corvallis, OR 97331 (United States); Clark, J, E-mail: schmitjo@engr.orst.ed [Department of Mechanical Engineering, Florida State University, Tallahassee, FL 32310 (United States)

    2009-12-15

    The spring loaded inverted pendulum template has been shown to accurately model the steady locomotion dynamics of a variety of running animals, and has served as the inspiration for an entire class of dynamic running robots. While the template models the leg dynamics by an energy-conserving spring, insects and animals have structures that dissipate, store and produce energy during a stance phase. Recent investigations into the spring-like properties of limbs, as well as animal response to drop-step perturbations, suggest that animals use their legs to manage energy storage and dissipation, and that this management is important for gait stability. In this paper, we extend our previous analysis of control of the spring loaded inverted pendulum template via changes in the leg touch-down angle to include energy variations during the stance phase. Energy variations are incorporated through leg actuation that varies the force-free leg length during the stance phase, yet maintains qualitatively correct force and velocity profiles. In contrast to the partially asymptotically stable gaits identified in previous analyses, incorporating energy and leg angle variations in this manner produces complete asymptotic stability. Drop-step perturbation simulations reveal that the control strategy is rather robust, with gaits recovering from drops of up to 30% of the nominal hip height.

  12. A Numerical Study on Hydrodynamics of Pectoral Fin Locomotion in Batoid Fishes

    Science.gov (United States)

    Hu, W. R.

    The mechanics of aquatic locomotion are of interest to biologists, dynamicists and engineers. Batoid fishes (skates and rays) propel themselves through the water primarily with their greatly expanded pectoral fins (pectoral-fin-based locomotion). Batoids exhibit two modes of pectoral swiminng behavior: (1) undulatory locomotion, termed ‘rajiform’, and (2) oscillatory locomotion, termed ‘mobuliform’. A computational study on the unsteady hydrodynamics of pectoral fin locomotion of Rhinoptera Bonasus and Dasyatis Sabina is carried out and presented, which represent the undulatory and oscillatory locomotion, respectively. Unsteady hydrodynamics around a pectoral fin is solved by a time-accurate solution of incompressible, laminar Navier-Stokes equations. Kinematic data of the pectoral fin locomotion used in the computational modeling are based on the experimental results. The pressure distribution of the pectoral fin was computed and integrated to give forces which were decomposed into lift and thrust. The velocity and vorticity field variation on the surface of pectoral fins and in the near-wake was computed throughout the swimming cycle. In the present study, we analyzed and compared the hydrodynamics and mechanmism of the Batoid pectoral fin locomotion between the two modes, and discovered how these patterns change with controllable factors, such as Renolds number, frequency, amplitude etc. The results show that forces on the fins of Rhinoptera Bonasus are much larger than that of Dasyatis Sabina. The load-bearing areas of Rhinoptera Bonasus are at the areas from the leading edge to the medial of the wing; while the load-bearing area of Dasyatis Sabina is the whole wavy fin. These characters are associated with the morphology of the wing skeleton. The propulsive mechanism of pectoral-fin-based locomotion is similar to that of the caudal-fin-based locomotion. A strong backward jet-stream in the wake contributes the net thrust, which is induced by the

  13. Full-scale locomotive dynamic crash testing and correlations : C-39 type locomotive colliding with a loaded hopper car (test 7).

    Science.gov (United States)

    2011-09-01

    This report presents the results of a locomotive and three loaded hopper car consist traveling at 29 miles per hour colliding with a stationary consist of 35 loaded hopper cars. The details of test instrumentation, LS-DYNA finite element simulation, ...

  14. Utilisation de modèles inspirés de l'humain pour guider la locomotion des robots

    OpenAIRE

    Vassallo , Christian

    2016-01-01

    This thesis has been done within the framework of the European Project Koroibot which aims at developing advanced algorithms to improve the humanoid robots locomotion. It is organized in three parts. With the aim of steering robots in a safe and efficient manner among humans it is required to understand the rules, principles and strategies of human during locomotion and transfer them to robots. The goal of this thesis is to investigate and identify the human locomotion strategies and create a...

  15. UTILISATION DES MODÈLES INSPIRÉS DE L'HUMAIN POUR LE GUIDAGE DE LA LOCOMOTION DE ROBOTS

    OpenAIRE

    Vassallo, Christian

    2016-01-01

    This thesis has been done within the framework of the European Project Koroibot which aims at developing advanced algorithms to improve the humanoid robots locomotion. It is organized in three parts. With the aim of steering robots in a safe and efficient manner among humans it is required to understand the rules, principles and strategies of human during locomotion and transfer them to robots. The goal of this thesis is to investigate and identify the human locomotion strategies and create a...

  16. Mechanical switching of ferroelectric domains beyond flexoelectricity

    Science.gov (United States)

    Chen, Weijin; Liu, Jianyi; Ma, Lele; Liu, Linjie; Jiang, G. L.; Zheng, Yue

    2018-02-01

    The resurgence of interest in flexoelectricity has prompted discussions on the feasibility of switching ferroelectric domains 'non-electrically'. In this work, we perform three-dimensional thermodynamic simulations in combination with ab initio calculations and effective Hamiltonian simulations to demonstrate the great effects of surface screening and surface bonding on ferroelectric domain switching triggered by local tip loading. A three-dimensional simulation scheme has been developed to capture the tip-induced domain switching behavior in ferroelectric thin films by adequately taking into account the surface screening effect and surface bonding effect of the ferroelectric film, as well as the finite elastic stiffness of the substrate and the electrode layers. The major findings are as follows. (i) Compared with flexoelectricity, surface effects can be overwhelming and lead to much more efficient mechanical switching caused by tip loading. (ii) The surface-assisted mechanical switching can be bi-directional without the necessity of reversing strain gradients. (iii) A mode transition from local to propagating domain switching occurs when the screening below a critical value. A ripple effect of domain switching appears with the formation of concentric loop domains. (iv) The ripple effect can lead to 'domain interference' and a deterministic writing of confined loop domain patterns by local excitations. Our study reveals the hidden switching mechanisms of ferroelectric domains and the possible roles of surface in mechanical switching. The ripple effect of domain switching, which is believed to be general in dipole systems, broadens our current knowledge of domain engineering.

  17. Experiments on vibration-driven stick-slip locomotion: A sliding bifurcation perspective

    Science.gov (United States)

    Du, Zhouwei; Fang, Hongbin; Zhan, Xiong; Xu, Jian

    2018-05-01

    Dry friction appears at the contact interface between two surfaces and is the source of stick-slip vibrations. Instead of being a negative factor, dry friction is essential for vibration-driven locomotion system to take effect. However, the dry-friction-induced stick-slip locomotion has not been fully understood in previous research, especially in terms of experiments. In this paper, we experimentally study the stick-slip dynamics of a vibration-driven locomotion system from a sliding bifurcation perspective. To this end, we first design and build a vibration-driven locomotion prototype based on an internal piezoelectric cantilever. By utilizing the mechanical resonance, the small piezoelectric deformation is significantly amplified to drive the prototype to achieve effective locomotion. Through identifying the stick-slip characteristics in velocity histories, we could categorize the system's locomotion into four types and obtain a stick-slip categorization diagram. In each zone of the diagram the locomotion exhibits qualitatively different stick-slip dynamics. Such categorization diagram is actually a sliding bifurcation diagram; crossing from one stick-slip zone to another corresponds to the triggering of a sliding bifurcation. In addition, a simplified single degree-of-freedom model is established, with the rationality of simplification been explained theoretically and numerically. Based on the equivalent model, a numerical stick-slip categorization is also obtained, which shows good agreement with the experiments both qualitatively and quantitatively. To the best of our knowledge, this is the first work that experimentally generates a sliding bifurcation diagram. The obtained stick-slip categorizations deepen our understanding of stick-slip dynamics in vibration-driven systems and could serve as a base for system design and optimization.

  18. Performance analysis of locomotive park of the transport service of rolling mills metallurgical enterprises

    Directory of Open Access Journals (Sweden)

    Ганна Вікторовна Маслак

    2017-07-01

    Full Text Available In terms of market economy it is highly important to implement new transport and energy-saving technologies into industrial enterprises and industrial objects’ workflow. And the main point here is employment of traction means which secure considerable economy in transport costs and, first and foremost, energy consumption. The issue of transport service of the rolling shop at a metallurgical enterprise is of high importance from the point of view of railway traction means utilization effectiveness, i.e. locomotives utilization within the process of shunting (which is carried out at railway tracks serving loading and unloading sites of the rolling shop. The article assesses operational indicators of locomotives’ performance by the time, power and adhesion weight within serving transport-and-handling complex of rolling shop at metallurgical enterprise. With this purpose transport technology of transport-and-handling complex of rolling shop is taken into consideration. In order to make the performance assessment of the locomotive fleet operation, algorithm of research has been developed. In accordance with this algorithm, operational parameters for TGM-4 locomotives exploitation have been defined (the data is provided for locomotive operation during a shift.Adhesion weight and locomotive power calculations have been made for work and after-hours runs. The analysis shows the level of inefficiency of locomotives use. One of the main ways of saving these costs is substitution of high-powered locomotives with energy-saving traction means. This issue can be solved at the expense of traction means based on wheeled tractors or self-propelled chassis which can be used either on a road or on a railway track. In accordance with operational conditions, qualification of tractive effort and other parameters, the effectiveness of traction means utilization at railway- and auto-transportations significantly increases

  19. Translation of the rat thoracic contusion model; part 2 - forward versus backward locomotion testing.

    Science.gov (United States)

    van Gorp, S; Leerink, M; Nguyen, S; Platoshyn, O; Marsala, M; Joosten, E A

    2014-07-01

    Experimental animal study. Locomotion analyses in rat spinal cord contusion injury (SCI) models are widely used for the evaluation of recovery of supraspinal locomotor control. However, many commonly used locomotion tests are inadequate to test for spinal cord integrity as they assess motor function that can be highly mediated through below-level propriospinal pattern-generating circuitry, independently of below-level perception. Here we report a behavioral motor test that is more sensitive for spinal cord integrity, even 6 weeks after injury: the backward locomotion rotating rod. University of California - San Diego. A modified rotating rod test was run in reverse. The rod diameter was increased and thin rubber lining was added. As a reference, we included commonly used motor tests: BBB score, catwalk gait analysis, motor-evoked potentials, single frame analyses, a forward rotating rod test and the 55° inclined ladder test. Unlike commonly used motor tests, the backward locomotion rotating rod test significantly discriminates between both sham-operated (falling latency: 20.4 s s.d.±4.5) vs mild SCI animals, and mild vs moderate SCI animals (differences between each group at acute, subacute and chronic phases: ⩾6 s, P⩽0.01). Moderate SCI animals were practically unable to make even slight backward hindpaw movements. The backward locomotion ability in the chronic phase correlates best with BBB locomotor scores from the acute phase. Our data show that backward locomotion is a highly sensitive and quick test to discriminate between sham, mild and moderate SCI, even after 6 weeks. Backward locomotion testing may improve the translational value of experimental results for the clinic.

  20. The effects of dissolved oxygen levels on the metabolic interaction between digestion and locomotion in Cyprinid fishes with different locomotive and digestive performances.

    Science.gov (United States)

    Zhang, Wei; Cao, Zhen-Dong; Fu, Shi-Jian

    2012-07-01

    To test whether the effects of water oxygen concentration ([O(2)]) on the metabolic interaction between locomotion and digestion differ between fish species with different locomotive and digestive behaviours in normoxia, we investigated the swimming performance of fasted and fed fish at water [O(2)] of 1, 2 and 8 (normoxia) mg L(-1) (2.5, 5 and 20 kPa) at 25°C in three juvenile Cyprinidae fish species: goldfish (Carassius auratus), common carp (Cyprinus carpio) and qingbo (Spinibarbus sinensis). Digestion, taxon and water [O(2)] all had significant effects on the pre-exercise oxygen consumption rate [Formula: see text] and the swimming performance (P swimming performance and the lowest feeding [Formula: see text] at the saturated water [O(2)], and its active oxygen consumption rate [Formula: see text] and critical swimming speed (U (crit)) decreased the most with decreases in water [O(2)]. Qingbo exhibited a locomotion-priority metabolic mode at all three water [O(2)]. Digestion was sacrificed to locomotion in a postprandial swimming situation, but fed qingbo could not maintain their U (crit) at water [O(2)] of 2 and 1 mg L(-1). Goldfish showed the lowest swimming performance and the highest feeding [Formula: see text] at the saturated water [O(2)]. They exhibited a digestion-priority metabolic mode at high water [O(2)]. However, with a decrease in water [O(2)], the feeding [Formula: see text] decreased more acutely than the respiratory capacity; thus, digestion and locomotion performed independently in a postprandial swimming situation (i.e., an additive metabolic mode) at a water [O(2)] of 1 mg L(-1). The common carp showed moderate and balanced swimming performance and feeding [Formula: see text] at the saturated water [O(2)], and exhibited an additive metabolic mode at all 3 water [O(2)], because digestion, swimming and respiratory capacities decreased in parallel with the decrease in water [O(2)].

  1. Biomechanics of the Treadmill Locomotion on the International Space Station

    Science.gov (United States)

    DeWitt, John; Cromwell, R. L.; Ploutz-Snyder, L. L.

    2014-01-01

    Exercise prescriptions completed by International Space Station (ISS) crewmembers are typically based upon evidence obtained during ground-based investigations, with the assumption that the results of long-term training in weightlessness will be similar to that attained in normal gravity. Coupled with this supposition are the assumptions that exercise motions and external loading are also similar between gravitational environments. Normal control of locomotion is dependent upon learning patterns of muscular activation and requires continual monitoring of internal and external sensory input [1]. Internal sensory input includes signals that may be dependent on or independent of gravity. Bernstein hypothesized that movement strategy planning and execution must include the consideration of segmental weights and inertia [2]. Studies of arm movements in microgravity showed that individuals tend to make errors but that compensation strategies result in adaptations, suggesting that control mechanisms must include peripheral information [3-5]. To date, however, there have been no studies examining a gross motor activity such as running in weightlessness other than using microgravity analogs [6-8]. The objective of this evaluation was to collect biomechanical data from crewmembers during treadmill exercise before and during flight. The goal was to determine locomotive biomechanics similarities and differences between normal and weightless environments. The data will be used to optimize future exercise prescriptions. This project addresses the Critical Path Roadmap risks 1 (Accelerated Bone Loss and Fracture Risk) and 11 (Reduced Muscle Mass, Strength, and Endurance). Data were collected from 7 crewmembers before flight and during their ISS missions. Before launch, crewmembers performed a single data collection session at the NASA Johnson Space Center. Three-dimensional motion capture data were collected for 30 s at speeds ranging from 1.5 to 9.5 mph in 0.5 mph increments

  2. Switching model photovoltaic pumping system

    Science.gov (United States)

    Anis, Wagdy R.; Abdul-Sadek Nour, M.

    Photovoltaic (PV) pumping systems are widely used due to their simplicity, high reliability and low cost. A directly-coupled PV pumping system is the most reliable and least-cost PV system. The d.c. motor-pump group is not, however, working at its optimum operating point. A battery buffered PV pumping system introduces a battery between the PV array and the d.c. motor-pump group to ensure that the motor-pump group is operating at its optimum point. The size of the battery storage depends on system economics. If the battery is fully charged while solar radiation is available, the battery will discharge through the load while the PV array is disconnected. Hence, a power loss takes place. To overcome the above mentioned difficulty, a switched mode PV pumping is proposed. When solar radiation is available and the battery is fully charged, the battery is disconnected and the d.c. motor-pump group is directly coupled to the PV array. To avoid excessive operating voltage for the motor, a part of the PV array is switched off to reduce the voltage. As a result, the energy loss is significantly eliminated. Detailed analysis of the proposed system shows that the discharged water increases by about 10% when compared with a conventional battery-buffered system. The system transient performance just after the switching moment shows that the system returns to a steady state in short period. The variations in the system parameters lie within 1% of the rated values.

  3. Neural network estimation of balance control during locomotion.

    Science.gov (United States)

    Hahn, Michael E; Farley, Arthur M; Lin, Victor; Chou, Li-Shan

    2005-04-01

    Gait patterns of the elderly are often adjusted to accommodate for reduced function in the balance control system and a general reduction in skeletal muscle strength. Recent studies have demonstrated that measures related to motion of whole body center of mass (COM) can distinguish elderly individuals with balance impairment from healthy peers. Accurate COM estimation requires a multiple-segment anthropometric model, which may restrict its broad application in assessment of dynamic instability. Although temporal-distance measures and electromyography have been used in evaluation of overall gait function and determination of gait dysfunction, no studies have examined the use of gait measurements in predicting COM motion during gait. The purpose of this study was to demonstrate the effectiveness of an artificial neural network (ANN) model in mapping gait measurements onto COM motion in the frontal plane. Data from 40 subjects of varied age and balance impairment were entered into a 3-layer feed-forward model with back-propagated error correction. Bootstrap re-sampling was used to enhance the generalization accuracy of the model, using 20 re-sampling trials. The ANN model required minimal processing time (5 epochs, with 20 hidden units) and accurately mapped COM motion (R-values up to 0.89). As training proportion and number of hidden units increased, so did model accuracy. Overall, this model appears to be effective as a mapping tool for estimating balance control during locomotion. With easily obtained gait measures as input and a simple, computationally efficient architecture, the model may prove useful in clinical scenarios where electromyography equipment exists.

  4. Decoding bipedal locomotion from the rat sensorimotor cortex

    Science.gov (United States)

    Rigosa, J.; Panarese, A.; Dominici, N.; Friedli, L.; van den Brand, R.; Carpaneto, J.; DiGiovanna, J.; Courtine, G.; Micera, S.

    2015-10-01

    Objective. Decoding forelimb movements from the firing activity of cortical neurons has been interfaced with robotic and prosthetic systems to replace lost upper limb functions in humans. Despite the potential of this approach to improve locomotion and facilitate gait rehabilitation, decoding lower limb movement from the motor cortex has received comparatively little attention. Here, we performed experiments to identify the type and amount of information that can be decoded from neuronal ensemble activity in the hindlimb area of the rat motor cortex during bipedal locomotor tasks. Approach. Rats were trained to stand, step on a treadmill, walk overground and climb staircases in a bipedal posture. To impose this gait, the rats were secured in a robotic interface that provided support against the direction of gravity and in the mediolateral direction, but behaved transparently in the forward direction. After completion of training, rats were chronically implanted with a micro-wire array spanning the left hindlimb motor cortex to record single and multi-unit activity, and bipolar electrodes into 10 muscles of the right hindlimb to monitor electromyographic signals. Whole-body kinematics, muscle activity, and neural signals were simultaneously recorded during execution of the trained tasks over multiple days of testing. Hindlimb kinematics, muscle activity, gait phases, and locomotor tasks were decoded using offline classification algorithms. Main results. We found that the stance and swing phases of gait and the locomotor tasks were detected with accuracies as robust as 90% in all rats. Decoded hindlimb kinematics and muscle activity exhibited a larger variability across rats and tasks. Significance. Our study shows that the rodent motor cortex contains useful information for lower limb neuroprosthetic development. However, brain-machine interfaces estimating gait phases or locomotor behaviors, instead of continuous variables such as limb joint positions or speeds

  5. Phalangeal joints kinematics during ostrich (Struthio camelus locomotion

    Directory of Open Access Journals (Sweden)

    Rui Zhang

    2017-01-01

    Full Text Available The ostrich is a highly cursorial bipedal land animal with a permanently elevated metatarsophalangeal joint supported by only two toes. Although locomotor kinematics in walking and running ostriches have been examined, these studies have been largely limited to above the metatarsophalangeal joint. In this study, kinematic data of all major toe joints were collected from gaits with double support (slow walking to running during stance period in a semi-natural setup with two selected cooperative ostriches. Statistical analyses were conducted to investigate the effect of locomotor gait on toe joint kinematics. The MTP3 and MTP4 joints exhibit the largest range of motion whereas the first phalangeal joint of the 4th toe shows the largest motion variability. The interphalangeal joints of the 3rd and 4th toes present very similar motion patterns over stance phases of slow walking and running. However, the motion patterns of the MTP3 and MTP4 joints and the vertical displacement of the metatarsophalangeal joint are significantly different during running and slow walking. Because of the biomechanical requirements, osctriches are likely to select the inverted pendulum gait at low speeds and the bouncing gait at high speeds to improve movement performance and energy economy. Interestingly, the motions of the MTP3 and MTP4 joints are highly synchronized from slow to fast locomotion. This strongly suggests that the 3rd and 4th toes really work as an “integrated system” with the 3rd toe as the main load bearing element whilst the 4th toe as the complementary load sharing element with a primary role to ensure the lateral stability of the permanently elevated metatarsophalangeal joint.

  6. Role of phosphodiesterase-4 on ethanol elicited locomotion and narcosis.

    Science.gov (United States)

    Baliño, Pablo; Ledesma, Juan Carlos; Aragon, Carlos M G

    2016-02-01

    The cAMP signaling pathway has emerged as an important modulator of the pharmacological effects of ethanol. In this respect, the cAMP-dependent protein kinase has been shown to play an important role in the modulation of several ethanol-induced behavioral actions. Cellular levels of cAMP are maintained by the activity of adenylyl cyclases and phosphodiesterases. In the present work we have focused on ascertaining the role of PDE4 in mediating the neurobehavioral effects of ethanol. For this purpose, we have used the selective PDE4 inhibitor Ro 20-1724. This compound has been proven to enhance cellular cAMP response by PDE4 blockade and can be administered systemically. Swiss mice were injected intraperitoneally (i.p.) with Ro 20-1724 (0-5 mg/kg; i.p.) at different time intervals before ethanol (0-4 g/kg; i.p.) administration. Immediately after the ethanol injection, locomotor activity, loss of righting reflex, PKA footprint and enzymatic activity were assessed. Pretreatment with Ro 20-1724 increased ethanol-induced locomotor stimulation in a dose-dependent manner. Doses that increased locomotor stimulation did not modify basal locomotion or the suppression of motor activity produced by high doses of this alcohol. Ro 20-1724 did not alter the locomotor activation produced by amphetamine or cocaine. The time of loss of righting reflex evoked by ethanol was increased after pretreatment with Ro 20-1724. This effect was selective for the narcotic effects of ethanol since Ro 20-1724 did not affect pentobarbital-induced narcotic effects. Moreover, Ro 20-1724 administration increased the PKA footprint and enzymatic activity response elicited by ethanol. These data provide further evidence of the key role of the cAMP signaling pathway in the central effects of ethanol. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Radiation-sensitive switching circuits

    Energy Technology Data Exchange (ETDEWEB)

    Moore, J.H.; Cockshott, C.P.

    1976-03-16

    A radiation-sensitive switching circuit has a light emitting diode which supplies light to a photo-transistor, the light being interrupted from time to time. When the photo-transistor is illuminated, current builds up and when this current reaches a predetermined value, a trigger circuit changes state. The peak output of the photo-transistor is measured and the trigger circuit is arranged to change state when the output of the device is a set proportion of the peak output, so as to allow for aging of the components. The circuit is designed to control the ignition system in an automobile engine.

  8. Radiation-sensitive switching circuits

    Energy Technology Data Exchange (ETDEWEB)

    Moore, J.H.; Cockshott, C.P.

    1976-03-16

    A radiation-sensitive switching circuit includes a light emitting diode which from time to time illuminates a photo-transistor, the photo-transistor serving when its output reaches a predetermined value to operate a trigger circuit. In order to allow for aging of the components, the current flow through the diode is increased when the output from the transistor falls below a known level. Conveniently, this is achieved by having a transistor in parallel with the diode, and turning the transistor off when the output from the phototransistor becomes too low. The circuit is designed to control the ignition system in an automobile engine.

  9. Laser-triggered vacuum switch

    Science.gov (United States)

    Brannon, Paul J.; Cowgill, Donald F.

    1990-01-01

    A laser-triggered vacuum switch has a material such as a alkali metal halide on the cathode electrode for thermally activated field emission of electrons and ions upon interaction with a laser beam, the material being in contact with the cathode with a surface facing the discharge gap. The material is preferably a mixture of KCl and Ti powders. The laser may either shine directly on the material, preferably through a hole in the anode, or be directed to the material over a fiber optic cable.

  10. MEMS switches having non-metallic crossbeams

    Science.gov (United States)

    Scardelletti, Maximillian C (Inventor)

    2009-01-01

    A RF MEMS switch comprising a crossbeam of SiC, supported by at least one leg above a substrate and above a plurality of transmission lines forming a CPW. Bias is provided by at least one layer of metal disposed on a top surface of the SiC crossbeam, such as a layer of chromium followed by a layer of gold, and extending beyond the switch to a biasing pad on the substrate. The switch utilizes stress and conductivity-controlled non-metallic thin cantilevers or bridges, thereby improving the RF characteristics and operational reliability of the switch. The switch can be fabricated with conventional silicon integrated circuit (IC) processing techniques. The design of the switch is very versatile and can be implemented in many transmission line mediums.

  11. On formalism and stability of switched systems

    DEFF Research Database (Denmark)

    Leth, John-Josef; Wisniewski, Rafal

    2012-01-01

    In this paper, we formulate a uniform mathematical framework for studying switched systems with piecewise linear partitioned state space and state dependent switching. Based on known results from the theory of differential inclusions, we devise a Lyapunov stability theorem suitable for this class...... of switched systems. With this, we prove a Lyapunov stability theorem for piecewise linear switched systems by means of a concrete class of Lyapunov functions. Contrary to existing results on the subject, the stability theorems in this paper include Filippov (or relaxed) solutions and allow infinite switching...... in finite time. Finally, we show that for a class of piecewise linear switched systems, the inertia of the system is not sufficient to determine its stability. A number of examples are provided to illustrate the concepts discussed in this paper....

  12. Switching control of an R/C hovercraft: stabilization and smooth switching.

    Science.gov (United States)

    Tanaka, K; Iwasaki, M; Wang, H O

    2001-01-01

    This paper presents stable switching control of an radio-controlled (R/C) hovercraft that is a nonholonomic (nonlinear) system. To exactly represent its nonlinear dynamics, more importantly, to maintain controllability of the system, we newly propose a switching fuzzy model that has locally Takagi-Sugeno (T-S) fuzzy models and switches them according to states, external variables, and/or time. A switching fuzzy controller is constructed by mirroring the rule structure of the switching fuzzy model of an R/C hovercraft. We derive linear matrix inequality (LMI) conditions for ensuring the stability of the closed-loop system consisting of a switching fuzzy model and controller. Furthermore, to guarantee smooth switching of control input at switching boundaries, we also derive a smooth switching condition represented in terms of LMIs. A stable switching fuzzy controller satisfying the smooth switching condition is designed by simultaneously solving both of the LMIs. The simulation and experimental results for the trajectory control of an R/C hovercraft show the validity of the switching fuzzy model and controller design, particularly, the smooth switching condition.

  13. Locomotion Enhances Neural Encoding of Visual Stimuli in Mouse V1.

    Science.gov (United States)

    Dadarlat, Maria C; Stryker, Michael P

    2017-04-05

    Neurons in mouse primary visual cortex (V1) are selective for particular properties of visual stimuli. Locomotion causes a change in cortical state that leaves their selectivity unchanged but strengthens their responses. Both locomotion and the change in cortical state are thought to be initiated by projections from the mesencephalic locomotor region, the latter through a disinhibitory circuit in V1. By recording simultaneously from a large number of single neurons in alert mice viewing moving gratings, we investigated the relationship between locomotion and the information contained within the neural population. We found that locomotion improved encoding of visual stimuli in V1 by two mechanisms. First, locomotion-induced increases in firing rates enhanced the mutual information between visual stimuli and single neuron responses over a fixed window of time. Second, stimulus discriminability was improved, even for fixed population firing rates, because of a decrease in noise correlations across the population. These two mechanisms contributed differently to improvements in discriminability across cortical layers, with changes in firing rates most important in the upper layers and changes in noise correlations most important in layer V. Together, these changes resulted in a threefold to fivefold reduction in the time needed to precisely encode grating direction and orientation. These results support the hypothesis that cortical state shifts during locomotion to accommodate an increased load on the visual system when mice are moving. SIGNIFICANCE STATEMENT This paper contains three novel findings about the representation of information in neurons within the primary visual cortex of the mouse. First, we show that locomotion reduces by at least a factor of 3 the time needed for information to accumulate in the visual cortex that allows the distinction of different visual stimuli. Second, we show that the effect of locomotion is to increase information in cells of all

  14. Musculoskeletal modelling of an ostrich (Struthio camelus pelvic limb: influence of limb orientation on muscular capacity during locomotion

    Directory of Open Access Journals (Sweden)

    John R. Hutchinson

    2015-06-01

    Full Text Available We developed a three-dimensional, biomechanical computer model of the 36 major pelvic limb muscle groups in an ostrich (Struthio camelus to investigate muscle function in this, the largest of extant birds and model organism for many studies of locomotor mechanics, body size, anatomy and evolution. Combined with experimental data, we use this model to test two main hypotheses. We first query whether ostriches use limb orientations (joint angles that optimize the moment-generating capacities of their muscles during walking or running. Next, we test whether ostriches use limb orientations at mid-stance that keep their extensor muscles near maximal, and flexor muscles near minimal, moment arms. Our two hypotheses relate to the control priorities that a large bipedal animal might evolve under biomechanical constraints to achieve more effective static weight support. We find that ostriches do not use limb orientations to optimize the moment-generating capacities or moment arms of their muscles. We infer that dynamic properties of muscles or tendons might be better candidates for locomotor optimization. Regardless, general principles explaining why species choose particular joint orientations during locomotion are lacking, raising the question of whether such general principles exist or if clades evolve different patterns (e.g., weighting of muscle force–length or force–velocity properties in selecting postures. This leaves theoretical studies of muscle moment arms estimated for extinct animals at an impasse until studies of extant taxa answer these questions. Finally, we compare our model’s results against those of two prior studies of ostrich limb muscle moment arms, finding general agreement for many muscles. Some flexor and extensor muscles exhibit self-stabilization patterns (posture-dependent switches between flexor/extensor action that ostriches may use to coordinate their locomotion. However, some conspicuous areas of disagreement in our

  15. Quasi-dynamic walk of a quadruped locomotion robot using optimal tracking control

    International Nuclear Information System (INIS)

    Uchida, Hiroaki; Nonami, Kenzo; Chiba, Yasunori; Koyama, Kakutaro.

    1994-01-01

    Recently, many research works of quadruped locomotion robots, which are considered to be operable on irregular terrain, have been carried out. In the case of realizing ideal motion control of the quadruped locomotion robot, it is assumed that hierarchical cooperative control consisting of decentralized control and centralized control is desirable. In the case that the locomotion robot moves at high speed, it is impossible to follow the desired trajectory because using only the feedback control method includes time delay. It is known that feedforward control input is valid for such motion control. In this paper, decentralized control is realized to apply optimal tracking control using feedforward control input to the quadruped locomotion robot, as the first step. As a result, it is determined that the angle variation of the foot and the stride applying optimal tracking control input are large compared with using only feedback control. It is verified that feedforward control input is useful to control the trajectory of the tip of the foot in high speed locomotion. (author)

  16. Walking like dinosaurs: chickens with artificial tails provide clues about non-avian theropod locomotion.

    Science.gov (United States)

    Grossi, Bruno; Iriarte-Díaz, José; Larach, Omar; Canals, Mauricio; Vásquez, Rodrigo A

    2014-01-01

    Birds still share many traits with their dinosaur ancestors, making them the best living group to reconstruct certain aspects of non-avian theropod biology. Bipedal, digitigrade locomotion and parasagittal hindlimb movement are some of those inherited traits. Living birds, however, maintain an unusually crouched hindlimb posture and locomotion powered by knee flexion, in contrast to the inferred primitive condition of non-avian theropods: more upright posture and limb movement powered by femur retraction. Such functional differences, which are associated with a gradual, anterior shift of the centre of mass in theropods along the bird line, make the use of extant birds to study non-avian theropod locomotion problematic. Here we show that, by experimentally manipulating the location of the centre of mass in living birds, it is possible to recreate limb posture and kinematics inferred for extinct bipedal dinosaurs. Chickens raised wearing artificial tails, and consequently with more posteriorly located centre of mass, showed a more vertical orientation of the femur during standing and increased femoral displacement during locomotion. Our results support the hypothesis that gradual changes in the location of the centre of mass resulted in more crouched hindlimb postures and a shift from hip-driven to knee-driven limb movements through theropod evolution. This study suggests that, through careful experimental manipulations during the growth phase of ontogeny, extant birds can potentially be used to gain important insights into previously unexplored aspects of bipedal non-avian theropod locomotion.

  17. Walking like dinosaurs: chickens with artificial tails provide clues about non-avian theropod locomotion.

    Directory of Open Access Journals (Sweden)

    Bruno Grossi

    Full Text Available Birds still share many traits with their dinosaur ancestors, making them the best living group to reconstruct certain aspects of non-avian theropod biology. Bipedal, digitigrade locomotion and parasagittal hindlimb movement are some of those inherited traits. Living birds, however, maintain an unusually crouched hindlimb posture and locomotion powered by knee flexion, in contrast to the inferred primitive condition of non-avian theropods: more upright posture and limb movement powered by femur retraction. Such functional differences, which are associated with a gradual, anterior shift of the centre of mass in theropods along the bird line, make the use of extant birds to study non-avian theropod locomotion problematic. Here we show that, by experimentally manipulating the location of the centre of mass in living birds, it is possible to recreate limb posture and kinematics inferred for extinct bipedal dinosaurs. Chickens raised wearing artificial tails, and consequently with more posteriorly located centre of mass, showed a more vertical orientation of the femur during standing and increased femoral displacement during locomotion. Our results support the hypothesis that gradual changes in the location of the centre of mass resulted in more crouched hindlimb postures and a shift from hip-driven to knee-driven limb movements through theropod evolution. This study suggests that, through careful experimental manipulations during the growth phase of ontogeny, extant birds can potentially be used to gain important insights into previously unexplored aspects of bipedal non-avian theropod locomotion.

  18. A novel device for studying weight supported, quadrupedal overground locomotion in spinal cord injured rats.

    Science.gov (United States)

    Hamlin, Marvin; Traughber, Terence; Reinkensmeyer, David J; de Leon, Ray D

    2015-05-15

    Providing weight support facilitates locomotion in spinal cord injured animals. To control weight support, robotic systems have been developed for treadmill stepping and more recently for overground walking. We developed a novel device, the body weight supported ambulatory rodent trainer (i.e. BART). It has a small pneumatic cylinder that moves along a linear track above the rat. When air is supplied to the cylinder, the rats are lifted as they perform overground walking. We tested the BART device in rats that received a moderate spinal cord contusion injury and in normal rats. Locomotor training with the BART device was not performed. All of the rats learned to walk in the BART device. In the contused rats, significantly greater paw dragging and dorsal stepping occurred in the hindlimbs compared to normal. Providing weight support significantly raised hip position and significantly reduced locomotor deficits. Hindlimb stepping was tightly coupled to forelimb stepping but only when the contused rats stepped without weight support. Three weeks after the contused rats received a complete spinal cord transection, significantly fewer hindlimb steps were performed. Relative to rodent robotic systems, the BART device is a simpler system for studying overground locomotion. The BART device lacks sophisticated control and sensing capability, but it can be assembled relatively easily and cheaply. These findings suggest that the BART device is a useful tool for assessing quadrupedal, overground locomotion which is a more natural form of locomotion relative to treadmill locomotion. Published by Elsevier B.V.

  19. The role of the integument with respect to different modes of locomotion in the Nematalycidae (Endeostigmata).

    Science.gov (United States)

    Bolton, Samuel J; Bauchan, Gary R; Ochoa, Ronald; Pooley, Christopher; Klompen, Hans

    2015-02-01

    Previous research on the locomotion of the Nematalycidae has only been undertaken on Gordialycus, which is by far the most elongated genus of the family. Gordialycus is dependent on an unusual form of peristalsis to move around. It was not known whether the genera of Nematalycidae with shorter bodies also used this mode of locomotion. Our videographic recordings of Osperalycus did not reveal peristalsis. Instead, this mite appears to move around the mineral regolith via the expansion and constriction of the metapodosomal and genital region, allowing greater versatility in the way that the annular regions contract and extend. This type of locomotion would enable relatively short bodied nematalycids to anchor themselves into secure positions before extending their anterior regions through tight spaces. Low-temperature scanning electron micrographs show that the short bodied genera have integumental features that appear to be associated with this mode of locomotion. Peristalsis is almost certainly a more derived form of locomotion that is an adaptation to the unusually long body form of Gordialycus.

  20. Limb and Trunk Mechanisms for Balance Control during Locomotion in Quadrupeds

    Science.gov (United States)

    Musienko, Pavel E.; Deliagina, Tatiana G.; Gerasimenko, Yury P.; Orlovsky, Grigori N.

    2014-01-01

    In quadrupeds, the most critical aspect of postural control during locomotion is lateral stability. However, neural mechanisms underlying lateral stability are poorly understood. Here, we studied lateral stability in decerebrate cats walking on a treadmill with their hindlimbs. Two destabilizing factors were used: a brief lateral push of the cat and a sustained lateral tilt of the treadmill. It was found that the push caused considerable trunk bending and twisting, as well as changes in the stepping pattern, but did not lead to falling. Due to postural reactions, locomotion with normal body configuration was restored in a few steps. It was also found that the decerebrate cat could keep balance during locomotion on the laterally tilted treadmill. This postural adaptation was based on the transformation of the symmetrical locomotor pattern into an asymmetrical one, with different functional lengths of the right and left limbs. Then, we analyzed limb and trunk neural mechanisms contributing to postural control during locomotion. It was found that one of the limb mechanisms operates in the transfer phase and secures a standard (relative to the trunk) position for limb landing. Two other limb mechanisms operate in the stance phase; they counteract distortions of the locomotor pattern by regulating the limb stiffness. The trunk configuration mechanism controls the body shape on the basis of sensory information coming from trunk afferents. We suggest that postural reactions generated by these four mechanisms are integrated, thus forming a response of the whole system to perturbation of balance during locomotion. PMID:24741060

  1. Flexibility of the axial central pattern generator network for locomotion in the salamander.

    Science.gov (United States)

    Ryczko, D; Knüsel, J; Crespi, A; Lamarque, S; Mathou, A; Ijspeert, A J; Cabelguen, J M

    2015-03-15

    In tetrapods, limb and axial movements are coordinated during locomotion. It is well established that inter- and intralimb coordination show considerable variations during ongoing locomotion. Much less is known about the flexibility of the axial musculoskeletal system during locomotion and the neural mechanisms involved. Here we examined this issue in the salamander Pleurodeles waltlii, which is capable of locomotion in both aquatic and terrestrial environments. Kinematics of the trunk and electromyograms from the mid-trunk epaxial myotomes were recorded during four locomotor behaviors in freely moving animals. A similar approach was used during rhythmic struggling movements since this would give some insight into the flexibility of the axial motor system. Our results show that each of the forms of locomotion and the struggling behavior is characterized by a distinct combination of mid-trunk motor patterns and cycle durations. Using in vitro electrophysiological recordings in isolated spinal cords, we observed that the spinal networks activated with bath-applied N-methyl-d-aspartate could generate these axial motor patterns. In these isolated spinal cord preparations, the limb motor nerve activities were coordinated with each mid-trunk motor pattern. Furthermore, isolated mid-trunk spinal cords and hemicords could generate the mid-trunk motor patterns. This indicates that each side of the cord comprises a network able to generate coordinated axial motor activity. The roles of descending and sensory inputs in the behavior-related changes in axial motor coordination are discussed. Copyright © 2015 the American Physiological Society.

  2. Locomotion-Related Population Cortical Ca2+Transients in Freely Behaving Mice.

    Science.gov (United States)

    Zhang, Quanchao; Yao, Jiwei; Guang, Yu; Liang, Shanshan; Guan, Jiangheng; Qin, Han; Liao, Xiang; Jin, Wenjun; Zhang, Jianxiong; Pan, Junxia; Jia, Hongbo; Yan, Junan; Feng, Zhengzhi; Li, Weibing; Chen, Xiaowei

    2017-01-01

    Locomotion involves complex neural activity throughout different cortical and subcortical networks. The primary motor cortex (M1) receives a variety of projections from different brain regions and is responsible for executing movements. The primary visual cortex (V1) receives external visual stimuli and plays an important role in guiding locomotion. Understanding how exactly the M1 and the V1 are involved in locomotion requires recording the neural activities in these areas in freely moving animals. Here, we used an optical fiber-based method for the real-time monitoring of neuronal population activities in freely moving mice. We combined the bulk loading of a synthetic Ca 2+ indicator and the optical fiber-based Ca 2+ recordings of neuronal activities. An optical fiber 200 μm in diameter can detect the coherent activity of a subpopulation of neurons. In layer 5 of the M1 and V1, we showed that population Ca 2+ transients reliably occurred preceding the impending locomotion. Interestingly, the M1 Ca 2+ transients started ~100 ms earlier than that in V1. Furthermore, the population Ca 2+ transients were robustly correlated with head movements. Thus, our work provides a simple but efficient approach for monitoring the cortical Ca 2+ activity of a local cluster of neurons during locomotion in freely moving animals.

  3. Phase coordination and phase-velocity relationship in metameric robot locomotion.

    Science.gov (United States)

    Fang, Hongbin; Li, Suyi; Wang, K W; Xu, Jian

    2015-10-29

    This research proposes a new approach for the control of metameric robot locomotion via phase coordination. Unlike previous studies where global wave-like rules were pre-specified to construct the actuation sequence of segments, this phase coordination method generates robot locomotion by assigning the actuation phase differences between adjacent segments without any global prerequisite rules. To effectively coordinate the phase differences, different symmetry properties are introduced. Optimization is then carried out on various symmetrically coordinated phase-difference patterns to maximize the average steady-state velocity of the robot. It is shown that the maximum average velocity is always achieved when the reflectional symmetry is included in the phase-difference pattern, and the identical-phase-difference (IPD) pattern is preferred for implementation because it reduces the number of independent phase variables to only one without significant loss in locomotion performance. Extensive analytical investigations on the IPD pattern reveal the relationship between the average locomotion velocity and some important parameters. Theoretical findings on the relationship between the average velocity and the phase difference in the IPD pattern are verified via experimental investigations on an 8-segment earthworm-like metameric robot prototype. Finally, this paper reveals an interesting result that the optimized phase-difference pattern can naturally generate peristalsis waves in metameric robot locomotion without global prerequisite wave-like rules.

  4. Goal-directed multimodal locomotion through coupling between mechanical and attractor selection dynamics.

    Science.gov (United States)

    Nurzaman, S G; Yu, X; Kim, Y; Iida, F

    2015-03-26

    One of the most significant challenges in bio-inspired robotics is how to realize and take advantage of multimodal locomotion, which may help robots perform a variety of tasks adaptively in different environments. In order to address the challenge properly, it is important to notice that locomotion dynamics are the result of interactions between a particular internal control structure, the mechanical dynamics and the environment. From this perspective, this paper presents an approach to enable a robot to take advantage of its multiple locomotion modes by coupling the mechanical dynamics of the robot with an internal control structure known as an attractor selection model. The robot used is a curved-beam hopping robot; this robot, despite its simple actuation method, possesses rich and complex mechanical dynamics that are dependent on its interactions with the environment. Through dynamical coupling, we will show how this robot performs goal-directed locomotion by gracefully shifting between different locomotion modes regulated by sensory input, the robot's mechanical dynamics and an internally generated perturbation. The efficacy of the approach is validated and discussed based on the simulation and on real-world experiments.

  5. Biped locomotion control with compliance; Compliance wo mochiita nisoku soko robot no undo seigyo

    Energy Technology Data Exchange (ETDEWEB)

    Kawaji, S.; Ogasawara, K.; Iimori, J. [Kumamoto University, Kumamoto (Japan)

    1995-12-20

    Realization of stable walking motion of biped locomotive robot is one of difficult control problems, but it is very interesting both theoretically and practically from the view point of motion control. The authors have already reported that the locomotion rhythm plays an important role in walking motions, and confirmed experimentally that the control method based on the locomotion rhythm is effective. But, many uncertainties, e.g., the changes of robot dynamics and the interaction between the robot and the floor, may make the locomotion rhythm irregular. In this paper, we introduce the compliance into the control system in order to modify the original reference locomotion rhythm for stable walking under the existence of the uncertainties. Concretely a compliance control system for the contact leg is designed to modify the rhythm by changing the posture of the leg corresponding to the force acting from the body so that the robot may keep the equilibrium state dynamically. Finally the simulation results are given to illustrate the effectiveness of the proposed compliance control system. 21 refs., 12 figs., 3 tabs.

  6. Switching X-Ray Tubes Remotely

    Science.gov (United States)

    Bulthuis, Ronald V.

    1990-01-01

    Convenient switch and relay circuit reduces risk of accidents. Proposed switching circuit for x-ray inspection system enables operator to change electrical connections to x-ray tubes remotely. Operator simply flips switch on conveniently-located selector box to change x-ray heads. Indicator lights on selector box show whether 160 or 320-kV head connected. Relays in changeover box provides proper voltages and coolants. Chance of making wrong connections and damaging equipment eliminated.

  7. Switched reluctance drives for electric vehicle applications

    OpenAIRE

    Andrada Gascón, Pedro; Torrent Burgués, Marcel; Blanqué Molina, Balduino; Perat Benavides, Josep Ignasi

    2003-01-01

    Electric vehicles are the only alternative for a clean, efficient and environmentally friendly urban transport system. With the increasing interest in electric drives for electric vehicle propulsion. This paper first tries to explain why the switched reluctance drive is a strong candidate for electric vehicle applications. It then gives switched reluctance drive design guidelines for battery or fuel cell operated electric vehicles. Finally, it presents the design and simulation of a switched ...

  8. Optical Multidimensional Switching for Data Center Networks

    DEFF Research Database (Denmark)

    Kamchevska, Valerija

    2017-01-01

    , the limitations of previously proposed optical subwavelength switching technologies are discussed and a novel concept of optical time division multiplexed switching is proposed. A detailed elaboration of the envisioned scheme is given, with a special focus on the problem of synchronization. A novel...... synchronization algorithm for the Hi-Ring architecture is proposed and experimentally validated. Furthermore, software controlled switching in the data plane is experimentally demonstrated when the proposed algorithm is used for synchronization. Finally, integration is discussed from two different perspectives...

  9. Monitoring Mellanox Infiniband SX6036 switches

    CERN Document Server

    Agapiou, Marinos

    2017-01-01

    The SX6036 switches addressed by my project, are part of a fully non-blocking fat-tree cluster consisting of 72 servers and 6 Mellanox SX6036 Infiniband switches. My project is about retrieving the appropriate metrics from the Infiniband switch cluster, ingesting the data to Collectd and after my data are being transfered to CERN Database, they are being visualized via Grafana Dashboards.

  10. Atomic crystals resistive switching memory

    International Nuclear Information System (INIS)

    Liu Chunsen; Zhang David Wei; Zhou Peng

    2017-01-01

    Facing the growing data storage and computing demands, a high accessing speed memory with low power and non-volatile character is urgently needed. Resistive access random memory with 4F 2 cell size, switching in sub-nanosecond, cycling endurances of over 10 12 cycles, and information retention exceeding 10 years, is considered as promising next-generation non-volatile memory. However, the energy per bit is still too high to compete against static random access memory and dynamic random access memory. The sneak leakage path and metal film sheet resistance issues hinder the further scaling down. The variation of resistance between different devices and even various cycles in the same device, hold resistive access random memory back from commercialization. The emerging of atomic crystals, possessing fine interface without dangling bonds in low dimension, can provide atomic level solutions for the obsessional issues. Moreover, the unique properties of atomic crystals also enable new type resistive switching memories, which provide a brand-new direction for the resistive access random memory. (topical reviews)

  11. Atomic battery with beam switching

    International Nuclear Information System (INIS)

    Edling, E.A.; McKenna, R.P.; Peterick, E.Th. Jr.; Trexler, F.D.

    1984-01-01

    An electric power generating apparatus that is powered primarily by the emission of electrically charged particles from radio-active materials enclosed in an evacuated vessel of glass or the like. An arrangement of reflecting electrodes causes a beam of particles to switch back and forth at a high frequency between two collecting electrodes that are connected to a resonating tuned primary circuit consisting of an inductor with resonating capacitor. The reflecting electrodes are energized in the proper phase relationship to the collecting electrodes to insure sustained oscillation by means of a secondary winding coupled inductively to the primary winding and connected to the reflecting electrodes. Power may be drawn from the circuit at a stepped down voltage from a power take-off winding that is coupled to the primary winding. The disclosure also describes a collecting electrode arrangement consisting of multiple spatially separated electrodes which together serve to capture a maximum of the available particle energy. A self-starting arrangement for start of oscillations is described. A specially adapted version of the invention utilizes two complementary beams of oppositely charged particles which are switched alternatingly between the collecting electrodes

  12. Stochastic multistep polarization switching in ferroelectrics

    Science.gov (United States)

    Genenko, Y. A.; Khachaturyan, R.; Schultheiß, J.; Ossipov, A.; Daniels, J. E.; Koruza, J.

    2018-04-01

    Consecutive stochastic 90° polarization switching events, clearly resolved in recent experiments, are described by a nucleation and growth multistep model. It extends the classical Kolmogorov-Avrami-Ishibashi approach and includes possible consecutive 90°- and parallel 180° switching events. The model predicts the results of simultaneous time-resolved macroscopic measurements of polarization and strain, performed on a tetragonal Pb (Zr ,Ti ) O3 ceramic in a wide range of electric fields over a time domain of seven orders of magnitude. It allows the determination of the fractions of individual switching processes, their characteristic switching times, activation fields, and respective Avrami indices.

  13. The increased importance of sector switching

    DEFF Research Database (Denmark)

    Frederiksen, Anders; Hansen, Jesper Rosenberg

    2017-01-01

    Sector switching is an important phenomenon that casts light on public–private differences. Yet our knowledge about its prevalence and trends is limited. We study sector switching using unique Danish register-based employer–employee data covering more than 25 years. We find that sector switching...... constitutes 18.5% of all job-to-job mobility, and the trend is increasing both from public to private and from private to public. Sector switching is also generally increasing for middle managers, but for administrative professionals only the flows from private to public increase and for top managers only...

  14. Low-Voltage Switched-Capacitor Circuits

    DEFF Research Database (Denmark)

    Bidari, E.; Keskin, M.; Maloberti, F.

    1999-01-01

    Switched-capacitor stages are described which can function with very low (typically 1 V) supply voltages, without using voltage boosting or switched op-amps. Simulations indicate that high performance may be achieved using these circuits in filter or data converter applications.......Switched-capacitor stages are described which can function with very low (typically 1 V) supply voltages, without using voltage boosting or switched op-amps. Simulations indicate that high performance may be achieved using these circuits in filter or data converter applications....

  15. Heat switch technology for cryogenic thermal management

    Science.gov (United States)

    Shu, Q. S.; Demko, J. A.; E Fesmire, J.

    2017-12-01

    Systematic review is given of development of novel heat switches at cryogenic temperatures that alternatively provide high thermal connection or ideal thermal isolation to the cold mass. These cryogenic heat switches are widely applied in a variety of unique superconducting systems and critical space applications. The following types of heat switch devices are discussed: 1) magnetic levitation suspension, 2) shape memory alloys, 3) differential thermal expansion, 4) helium or hydrogen gap-gap, 5) superconducting, 6) piezoelectric, 7) cryogenic diode, 8) magneto-resistive, and 9) mechanical demountable connections. Advantages and limitations of different cryogenic heat switches are examined along with the outlook for future thermal management solutions in materials and cryogenic designs.

  16. Mechanism of single atom switch on silicon

    DEFF Research Database (Denmark)

    Quaade, Ulrich; Stokbro, Kurt; Thirstrup, C.

    1998-01-01

    We demonstrate single atom switch on silicon which operates by displacement of a hydrogen atom on the silicon (100) surface at room temperature. We find two principal effects by which the switch is controlled: a pronounced maximum of the switching probability as function of sample bias...... and a preferred direction of switching as function of STM tip position. Based on first principles calculations, are show that this behaviour is due to a novel mechanism involving an electronic excitation of a localized surface resonance. (C) 1998 Elsevier Science B.V. All rights reserved....

  17. Clocking Scheme for Switched-Capacitor Circuits

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper

    1998-01-01

    A novel clocking scheme for switched-capacitor (SC) circuits is presented. It can enhance the understanding of SC circuits and the errors caused by MOSFET (MOS) switches. Charge errors, and techniques to make SC circuits less sensitive to them are discussed.......A novel clocking scheme for switched-capacitor (SC) circuits is presented. It can enhance the understanding of SC circuits and the errors caused by MOSFET (MOS) switches. Charge errors, and techniques to make SC circuits less sensitive to them are discussed....

  18. The Neuropeptides FLP-2 and PDF-1 Act in Concert To Arouse Caenorhabditis elegans Locomotion.

    Science.gov (United States)

    Chen, Didi; Taylor, Kelsey P; Hall, Qi; Kaplan, Joshua M

    2016-11-01

    During larval molts, Caenorhabditis elegans exhibits a sleep-like state (termed lethargus) that is characterized by the absence of feeding and profound locomotion quiescence. The rhythmic pattern of locomotion quiescence and arousal linked to the molting cycle is mediated by reciprocal changes in sensory responsiveness, whereby arousal is associated with increased responsiveness. Sensory neurons arouse locomotion via release of a neuropeptide (PDF-1) and glutamate. Here we identify a second arousing neuropeptide (FLP-2). We show that FLP-2 acts via an orexin-like receptor (FRPR-18), and that FLP-2 and PDF-1 secretion are regulated by reciprocal positive feedback. These results suggest that the aroused behavioral state is stabilized by positive feedback between two neuropeptides. Copyright © 2016 by the Genetics Society of America.

  19. Numerical analysis of a unique mode of locomotion: vertical climbing by Pacific lamprey

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Q [Department of Structural Engineering, University of California, San Diego, La Jolla, CA (United States); Moser, M [Fish Ecology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, Seattle, WA (United States); Kemp, P, E-mail: qizhu@ucsd.edu [International Centre for Ecohydraulics Research, Faculty of Engineering and the Environment, University of Southampton, Southampton (United Kingdom)

    2011-03-15

    Pacific lampreys are capable of climbing vertical wetted surfaces through a two-phase (bending and stretching) locomotion mode using the oral disc for adherence. We investigate the physical mechanism and performance of this process by using a continuous beam model. Two mechanisms, one akin to the jumping process and the other related to the fast stretching of the body, have been identified. This locomotion mode may inspire biomimetic designs of anguilliform swimming devices capable of overcoming steep obstacles. By using a genetic algorithm simulation we identify the combination of kinematic parameters corresponding to optimal efficiency (defined as the gravitational potential energy gained in each climbing step divided by the energy spent to activate the motion). These parameters are similar to laboratory observations of lamprey motion, suggesting that this type of locomotion has been optimized for maximum efficiency through evolution.

  20. The Effects of Long-Duration Spaceflight on Postflight Terrestrial Locomotion

    Science.gov (United States)

    Bloomberg, J. J.; Mulavara, A. P.; McDonald, P. V.; Layne, C. S.; Merkle, L. A.; Cohen, H. S.; Kozlovskaya, I. B.

    1999-01-01

    Locomotion is a complex task requiring the coordinated integration of multiple sensorimotor subsystems. This coordination is exemplified by the precise control of segmental kinematics that allows smooth progression of movement in the face of changing environmental constraints. Exposure to the microgravity environment encountered during space flight induces adaptive modification in the central processing of sensory input to produce motor responses appropriate for the prevailing environment. This inflight adaptive change in sensorimotor function is inappropriate for movement control in 1-g and leads to postflight disturbances in terrestrial locomotor function. We have previously explored the effects of short-duration (7-16 days) space flight on the control of locomotion. The goal of the present set of studies was to investigate the effects of long-duration spaceflight (3-6 months) on the control of locomotion with particular emphasis on understanding how the multiple interacting systems are adaptively modified by prolonged microgravity exposure.

  1. Sensory Neurons Arouse C. elegans Locomotion via Both Glutamate and Neuropeptide Release.

    Directory of Open Access Journals (Sweden)

    Seungwon Choi

    2015-07-01

    Full Text Available C. elegans undergoes periods of behavioral quiescence during larval molts (termed lethargus and as adults. Little is known about the circuit mechanisms that establish these quiescent states. Lethargus and adult locomotion quiescence is dramatically reduced in mutants lacking the neuropeptide receptor NPR-1. Here, we show that the aroused locomotion of npr-1 mutants results from the exaggerated activity in multiple classes of sensory neurons, including nociceptive (ASH, touch sensitive (ALM and PLM, and stretch sensing (DVA neurons. These sensory neurons accelerate locomotion via both neuropeptide and glutamate release. The relative contribution of these sensory neurons to arousal differs between larval molts and adults. Our results suggest that a broad network of sensory neurons dictates transitions between aroused and quiescent behavioral states.

  2. The Neuropeptides FLP-2 and PDF-1 Act in Concert To Arouse Caenorhabditis elegans Locomotion

    Science.gov (United States)

    Chen, Didi; Taylor, Kelsey P.; Hall, Qi; Kaplan, Joshua M.

    2016-01-01

    During larval molts, Caenorhabditis elegans exhibits a sleep-like state (termed lethargus) that is characterized by the absence of feeding and profound locomotion quiescence. The rhythmic pattern of locomotion quiescence and arousal linked to the molting cycle is mediated by reciprocal changes in sensory responsiveness, whereby arousal is associated with increased responsiveness. Sensory neurons arouse locomotion via release of a neuropeptide (PDF-1) and glutamate. Here we identify a second arousing neuropeptide (FLP-2). We show that FLP-2 acts via an orexin-like receptor (FRPR-18), and that FLP-2 and PDF-1 secretion are regulated by reciprocal positive feedback. These results suggest that the aroused behavioral state is stabilized by positive feedback between two neuropeptides. PMID:27585848

  3. Sensory Neurons Arouse C. elegans Locomotion via Both Glutamate and Neuropeptide Release

    Science.gov (United States)

    Chatzigeorgiou, Marios; Hu, Zhitao; Schafer, William R.; Kaplan, Joshua M.

    2015-01-01

    C. elegans undergoes periods of behavioral quiescence during larval molts (termed lethargus) and as adults. Little is known about the circuit mechanisms that establish these quiescent states. Lethargus and adult locomotion quiescence is dramatically reduced in mutants lacking the neuropeptide receptor NPR-1. Here, we show that the aroused locomotion of npr-1 mutants results from the exaggerated activity in multiple classes of sensory neurons, including nociceptive (ASH), touch sensitive (ALM and PLM), and stretch sensing (DVA) neurons. These sensory neurons accelerate locomotion via both neuropeptide and glutamate release. The relative contribution of these sensory neurons to arousal differs between larval molts and adults. Our results suggest that a broad network of sensory neurons dictates transitions between aroused and quiescent behavioral states. PMID:26154367

  4. Fuzzy-logic-based hybrid locomotion mode classification for an active pelvis orthosis: Preliminary results.

    Science.gov (United States)

    Yuan, Kebin; Parri, Andrea; Yan, Tingfang; Wang, Long; Munih, Marko; Vitiello, Nicola; Wang, Qining

    2015-01-01

    In this paper, we present a fuzzy-logic-based hybrid locomotion mode classification method for an active pelvis orthosis. Locomotion information measured by the onboard hip joint angle sensors and the pressure insoles is used to classify five locomotion modes, including two static modes (sitting, standing still), and three dynamic modes (level-ground walking, ascending stairs, and descending stairs). The proposed method classifies these two kinds of modes first by monitoring the variation of the relative hip joint angle between the two legs within a specific period. Static states are then classified by the time-based absolute hip joint angle. As for dynamic modes, a fuzzy-logic based method is proposed for the classification. Preliminary experimental results with three able-bodied subjects achieve an off-line classification accuracy higher than 99.49%.

  5. 49 CFR 236.6 - Hand-operated switch equipped with switch circuit controller.

    Science.gov (United States)

    2010-10-01

    ... controller. 236.6 Section 236.6 Transportation Other Regulations Relating to Transportation (Continued... switch circuit controller. Hand-operated switch equipped with switch circuit controller connected to the point, or with facing-point lock and circuit controller, shall be so maintained that when point is open...

  6. Locomotion Efficiency Optimization of Biologically Inspired Snake Robots

    Directory of Open Access Journals (Sweden)

    Eleni Kelasidi

    2018-01-01

    Full Text Available Snake robots constitute bio-inspired solutions that have been studied due to their ability to move in challenging environments where other types of robots, such as wheeled or legged robots, usually fail. In this paper, we consider both land-based and swimming snake robots. One of the principal concerns of the bio-inspired snake robots is to increase the motion efficiency in terms of the forward speed by improving the locomotion methods. Furthermore, energy efficiency becomes a crucial challenge for this type of robots due to the importance of long-term autonomy of these systems. In this paper, we take into account both the minimization of the power consumption and the maximization of the achieved forward velocity in order to investigate the optimal gait parameters for bio-inspired snake robots using lateral undulation and eel-like motion patterns. We furthermore consider possible negative work effects in the calculation of average power consumption of underwater snake robots. To solve the multi-objective optimization problem, we propose transforming the two objective functions into a single one using a weighted-sum method. For different set of weight factors, Particle Swarm Optimization is applied and a set of optimal points is consequently obtained. Pareto fronts or trade-off curves are illustrated for both land-based and swimming snake robots with different numbers of links. Pareto fronts represent trade-offs between the objective functions. For example, how increasing the forward velocity results in increasing power consumption. Therefore, these curves are a very useful tool for the control and design of snake robots. The trade-off curve thus constitutes a very useful tool for both the control and design of bio-inspired snake robots. In particular, the operators or designers of bio-inspired snake robots can choose a Pareto optimal point based on the trade-off curve, given the preferred number of links on the robot. The optimal gait parameters

  7. Mechatronics by Analogy and Application to Legged Locomotion

    Science.gov (United States)

    Ragusila, Victor

    determined, the original mechanism is optimized such that its dynamic behaviour is analogous. It is shown that, if this analogy is achieved, the control system designed based on the simpler mechanisms can be directly implemented to the more complex system, and their dynamic behaviours are close enough for the system performance to be effectively the same. Finally it is shown that, for the employed objective of fast legged locomotion, the proposed methodology achieves a better design than Reduction-by-Feedback, a competing methodology that uses control layers to simplify the dynamics of the system.

  8. Nonlinear dendritic integration in CA1 pyramidal neurons during locomotion.

    Directory of Open Access Journals (Sweden)

    Jeff Magee

    2014-04-01

    Full Text Available Most neuronal circuits receive at least two functionally distinct input types (intrinsic vs. extrinsic; sensory vs. motor; etc. In many pyramidal neuron based microcircuits integration of these two input signals can proceed nonlinearly through the production of active dendritic voltage signals. For example, appropriately timed, perisomatically located, hippocampal (SC and distal dendrite targeting entorhinal (EC3 input produces a distal dendritic Ca2+ plateau potential that drives burst firing output from CA1 pyramidal neurons in vitro. Related signals have been observed in neocortical pyramidal neurons. Until recently it was unknown whether these events occurred in vivo and, if so, during what behavioral states. Here we used simultaneous whole-cell patch and field potential recordings in head-fixed mice running on a linear track treadmill to study this dendritic plateau driven burst firing (plateaus in CA1 neurons. We find that during locomotion dendritic plateau potentials occur within the neuron’s place field with initiation probability peaking near the peak of the firing field. Plateaus produce a large (32±4mV; n=12, slow (duration; 51±7ms somatic depolarization that appears similar to that measured in vitro. Interestingly, plateaus exhibit a dramatic level of theta-phase modulation (~97% that peaks late in the theta cycle (~330°. This late phase peak in plateau potential initiation is near the theta-phase preference of EC3 inputs, suggesting a theta-phase dependent interaction of SC and EC3 inputs. We tested this idea by manipulating the phase of SC inputs by injecting phase adjusted theta frequency currents into CA1 somas. Biasing AP firing earlier in the theta phase decreased plateau probability to ~48% of control whereas biasing AP firing later in phase increased plateau probability 276%. We next directly examined the role of EC3 inputs by inactivating the EC3 axons in CA1 via local light activation of axons expressing

  9. Different performances in static and dynamic imagery and real locomotion. An exploratory trial.

    Directory of Open Access Journals (Sweden)

    Augusto eFusco

    2014-10-01

    Full Text Available Motor imagery is a mental representation of an action without its physical execution. Recently, the simultaneous movement of the body has been added to the mental simulation. This refers to dynamic motor imagery (dMI. This study was aimed at analyzing the temporal features for static and dMI in different locomotor conditions (natural walking, NW, light running, LR, lateral walking, LW, backward walking, BW, and whether these performances were more related to all the given conditions or present only in walking. We have been also evaluated the steps performed in the dMI in comparison with the ones performed by real locomotion. Twenty healthy participants (29.3 ± 5.1 y. old were asked to move towards a visualized target located at 10mt. In dMI, no significant temporal differences respect the actual locomotion were found for all the given tasks (NW: p=0.058, LR: p=0.636, BW: p=0.096; LW: p=0,487. Significant temporal differences between static imagery and actual movements were found for LR (p<0.001 and LW (p<0.001, due to an underestimation of time needed to achieve the target in imagined locomotion. Significant differences in terms of number of steps among tasks were found for LW (p<0.001 and BW (p=0.036, whereas neither in NW (p=0.124 nor LR (p=0.391 between dMI and real locomotion.Our results confirmed that motor imagery is a task-dependent process, with walking being temporally closer than other locomotor conditions. Moreover, the time records of dynamic motor imagery are nearer to the ones of actual locomotion respect than the ones of static motor imagery. Keywords: Walking, dynamic motor imagery, human locomotion, chronometry.

  10. Pyramidal tract neurons receptive to different forelimb joints act differently during locomotion

    Science.gov (United States)

    Stout, Erik E.

    2012-01-01

    During locomotion, motor cortical neurons projecting to the pyramidal tract (PTNs) discharge in close relation to strides. How their discharges vary based on the part of the body they influence is not well understood. We addressed this question with regard to joints of the forelimb in the cat. During simple and ladder locomotion, we compared the activity of four groups of PTNs with somatosensory receptive fields involving different forelimb joints: 1) 45 PTNs receptive to movements of shoulder, 2) 30 PTNs receptive to movements of elbow, 3) 40 PTNs receptive to movements of wrist, and 4) 30 nonresponsive PTNs. In the motor cortex, a relationship exists between the location of the source of afferent input and the target for motor output. On the basis of this relationship, we inferred the forelimb joint that a PTN influences from its somatosensory receptive field. We found that different PTNs tended to discharge differently during locomotion. During simple locomotion shoulder-related PTNs were most active during late stance/early swing, and upon transition from simple to ladder locomotion they often increased activity and stride-related modulation while reducing discharge duration. Elbow-related PTNs were most active during late swing/early stance and typically did not change activity, modulation, or discharge duration on the ladder. Wrist-related PTNs were most active during swing and upon transition to the ladder often decreased activity and increased modulation while reducing discharge duration. These data suggest that during locomotion the motor cortex uses distinct mechanisms to control the shoulder, elbow, and wrist. PMID:22236716

  11. 49 CFR 222.45 - When is a railroad required to cease routine sounding of locomotive horns at crossings?

    Science.gov (United States)

    2010-10-01

    ... sounding of locomotive horns at crossings? 222.45 Section 222.45 Transportation Other Regulations Relating... Horns at Groups of Crossings-Quiet Zones § 222.45 When is a railroad required to cease routine sounding..., a railroad shall refrain from, or cease, routine sounding of the locomotive horn at all public...

  12. Does perceptual-motor calibration generalize across two different forms of locomotion? Investigations of walking and wheelchairs.

    Directory of Open Access Journals (Sweden)

    Benjamin R Kunz

    Full Text Available The relationship between biomechanical action and perception of self-motion during walking is typically consistent and well-learned but also adaptable. This perceptual-motor coupling can be recalibrated by creating a mismatch between the visual information for self-motion and walking speed. Perceptual-motor recalibration of locomotion has been demonstrated through effects on subsequent walking without vision, showing that learned perceptual-motor coupling influences a dynamic representation of one's spatial position during walking. Our present studies test whether recalibration of wheelchair locomotion, a novel form of locomotion for typically walking individuals, similarly influences subsequent wheelchair locomotion. Furthermore, we test whether adaptation to the pairing of visual information for self-motion during one form of locomotion transfers to a different locomotion modality. We find strong effects of perceptual-motor recalibration for matched locomotion modalities--walking/walking and wheeling/wheeling. Transfer across incongruent locomotion modalities showed weak recalibration effects. The results have implications both for theories of perceptual-motor calibration mechanisms and their effects on spatial orientation, as well as for practical applications in training and rehabilitation.

  13. 75 FR 20005 - Crawler, Locomotive, and Truck Cranes Standard; Extension of the Office of Management and Budget...

    Science.gov (United States)

    2010-04-16

    ... Occupational Safety and Health Administration Crawler, Locomotive, and Truck Cranes Standard; Extension of the... collection requirements contained in its Crawler, Locomotive, and Truck Cranes Standard (29 CFR 1910.180... read or download through the Web site. All submissions, including copyrighted material, are available...

  14. Three-dimensional Locomotion and Drilling Microrobot Using Electromagnetic Actuation System

    International Nuclear Information System (INIS)

    Li, Girl; Choi, Hyun Chul; Cha, Kyoung Rae; Jeong, Se Mi; Park, Jong Oh; Park, Suk Ho

    2011-01-01

    In this study, a novel electromagnetic microrobot system with locomotion and drilling functions in three dimensional space was developed. Because of size limitations, the microrobot does not have actuator, battery, and controller. Therefore, an electromagnetic actuation (EMA) system was used to drive the robot. The proposed EMA system consists of three rectangular Helmholtz coil pairs in x-, y- and z-axes and a Maxwell coil pair in the z-axis. The magnetic field generated in the EMA coil system could be controlled by the input current of the EMA coil. Finally, through various experiments, the locomotion and drilling performances of the proposed EMA microrobot system were verified

  15. Peristaltic Wave Locomotion and Shape Morphing with a Millipede Inspired System

    Science.gov (United States)

    Spinello, Davide; Fattahi, Javad S.

    2017-08-01

    We present the mechanical model of a bio-inspired deformable system, modeled as a Timoshenko beam, which is coupled to a substrate by a system of distributed elements. The locomotion action is inspired by the coordinated motion of coupling elements that mimic the legs of millipedes and centipedes, whose leg-to-ground contact can be described as a peristaltic displacement wave. The multi-legged structure is crucial in providing redundancy and robustness in the interaction with unstructured environments and terrains. A Lagrangian approach is used to derive the governing equations of the system that couple locomotion and shape morphing. Features and limitations of the model are illustrated with numerical simulations.

  16. Twisting and bending: the functional role of salamander lateral hypaxial musculature during locomotion.

    Science.gov (United States)

    Bennett, W O; Simons, R S; Brainerd, E L

    2001-06-01

    The function of the lateral hypaxial muscles during locomotion in tetrapods is controversial. Currently, there are two hypotheses of lateral hypaxial muscle function. The first, supported by electromyographic (EMG) data from a lizard (Iguana iguana) and a salamander (Dicamptodon ensatus), suggests that hypaxial muscles function to bend the body during swimming and to resist long-axis torsion during walking. The second, supported by EMG data from lizards during relatively high-speed locomotion, suggests that these muscles function primarily to bend the body during locomotion, not to resist torsional forces. To determine whether the results from D. ensatus hold for another salamander, we recorded lateral hypaxial muscle EMGs synchronized with body and limb kinematics in the tiger salamander Ambystoma tigrinum. In agreement with results from aquatic locomotion in D. ensatus, all four layers of lateral hypaxial musculature were found to show synchronous EMG activity during swimming in A. tigrinum. Our findings for terrestrial locomotion also agree with previous results from D. ensatus and support the torsion resistance hypothesis for terrestrial locomotion. We observed asynchronous EMG bursts of relatively high intensity in the lateral and medial pairs of hypaxial muscles during walking in tiger salamanders (we call these 'alpha-bursts'). We infer from this pattern that the more lateral two layers of oblique hypaxial musculature, Mm. obliquus externus superficialis (OES) and obliquus externus profundus (OEP), are active on the side towards which the trunk is bending, while the more medial two layers, Mm. obliquus internus (OI) and transversus abdominis (TA), are active on the opposite side. This result is consistent with the hypothesis proposed for D. ensatus that the OES and OEP generate torsional moments to counteract ground reaction forces generated by forelimb support, while the OI and TA generate torsional moments to counteract ground reaction forces from hindlimb

  17. Damages and resource of locomotive wheels used under the north operating conditions

    Directory of Open Access Journals (Sweden)

    A. V. Grigorev

    2014-01-01

    Full Text Available In operating railway equipment, in particular the elements, such as a wheel and a rail there is damage accumulation of any kind, causing a premature equipment failure. Thus, an analysis of the mechanisms and modeling of damage accumulation and fracture both on the surface and in the bulk material remain a challenge.Data on the defective wheel sets to be subjected to facing has been collected and analyzed to assess the locomotive wheel sets damage of the locomotive fleet company of AK «Yakutia Railways», city of Aldan, The Republic of Sakha (Yakutia. For this purpose, three main locomotives have been examined.The object of research carried out in this paper, is a locomotive wheels tire, which is subjected to cyclic impact (dynamic loads during operation. In this regard, the need arises to determine both the strength of material in response to such shock loads and the quantitative calculation of damage accumulated therein.The accumulated fatigue damage has been attributed to one radial cross section of the wheel coming into contact with the rail once per revolution of the wheel. Consequently, in one revolution a wheel is under one loading cycle. As stated, the average mileage of locomotives to have the unacceptable damages formed on the tread surface is 12 thousand km.Test results establish that along with the high-cycle loading the shock-contact action on rail joints significantly affects the accumulation of damage in the locomotive wheels tire. The number of cycles to failure due to the formation of unacceptable damage in the locomotive wheels tire is N = 2,4×106 and 6×105 cycles, respectively, for fatigue and shock-contact loading.In general, we can say that the problem of higher intensity to form the surface damage is directly related to the operation of the locomotive wheel tire under abnormally low climatic temperatures. With decreasing ambient temperature, this element material rapidly looses its plastic properties, thereby accelerating

  18. Three-dimensional Locomotion and Drilling Microrobot Using Electromagnetic Actuation System

    Energy Technology Data Exchange (ETDEWEB)

    Li, Girl; Choi, Hyun Chul; Cha, Kyoung Rae; Jeong, Se Mi; Park, Jong Oh; Park, Suk Ho [Chonnam National University, Gwangju (Korea, Republic of)

    2011-12-15

    In this study, a novel electromagnetic microrobot system with locomotion and drilling functions in three dimensional space was developed. Because of size limitations, the microrobot does not have actuator, battery, and controller. Therefore, an electromagnetic actuation (EMA) system was used to drive the robot. The proposed EMA system consists of three rectangular Helmholtz coil pairs in x-, y- and z-axes and a Maxwell coil pair in the z-axis. The magnetic field generated in the EMA coil system could be controlled by the input current of the EMA coil. Finally, through various experiments, the locomotion and drilling performances of the proposed EMA microrobot system were verified.

  19. Guide-dog robot Harunobu-5: a locomotion strategy sign-pattern-based stereotyped motion

    Science.gov (United States)

    Mori, Hideo; Yasutomi, Satoshi; Charkari, N. M.; Nishikawa, Kazuhiro; Yamaguchi, Kencihi; Kotani, Shinj

    1993-05-01

    A locomotion paradigm called 'sign pattern-based stereotyped motion' is described in this paper. It urges that the motion control patterns of the robot can be limited in to six primitive ones: Moving-Along, Moving-Toward, Moving-for-Sighting, Following-a-Person, Moving- through-Gate, Moving-along-Wall, and a locomotion from the starting point to the goal can be controlled by a sequence of these patterns. This paradigm is implemented in guide dog robot Harunobu-5, and tested in outdoor scene.

  20. Innovization procedure applied to a multi-objective optimization of a biped robot locomotion

    Science.gov (United States)

    Oliveira, Miguel; Santos, Cristina P.; Costa, Lino

    2013-10-01

    This paper proposes an Innovization procedure approach for a bio-inspired biped gait locomotion controller. We combine a multi-objective evolutionary algorithm and a bio-inspired Central Patterns Generator locomotion controller to generates the necessary limb movements to perform the walking gait of a biped robot. The search for the best set of CPG parameters is optimized by considering multiple objectives along a staged evolution. An innovation analysis is issued to verify relationships between the parameters and the objectives and between objectives themselves in order to find relevant motor behaviors characteristics. The simulation results show the effectiveness of the proposed approach.