scholarly journals Two pursuit strategies for a single sensorimotor control task in blowfly

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Leandre Varennes ◽  
Holger G. Krapp ◽  
Stephane Viollet
Keyword(s):  
Horizontal Plane ◽  
Vertical Plane ◽  
Rate Of Change ◽  
Proportional Navigation ◽  
Visuomotor Coordination ◽  
Control Laws ◽  
Bearing Angle ◽  
Kinematic Models ◽  
Heading Angle ◽  
The Difference

AbstractEffective visuomotor coordination is a necessary requirement for the survival of many terrestrial, aquatic, and aerial animal species. We studied the kinematics of aerial pursuit in the blowfly Lucilia sericata using an actuated dummy as target for freely flying males. We found that the flies perform target tracking in the horizontal plane and target interception in the vertical plane. Our behavioural data suggest that the flies’ trajectory changes are a controlled combination of target heading angle and of the rate of change of the bearing angle. We implemented control laws in kinematic models and found that the contributions of proportional navigation strategy are negligible. We concluded that the difference between horizontal and vertical control relates to the difference in target heading angle the fly keeps constant: 0° in azimuth and 23° in elevation. Our work suggests that male Lucilia control both horizontal and vertical steerings by employing proportional controllers to the error angles. In horizontal plane, this controller operates at time delays as small as 10 ms, the fastest steering response observed in any flying animal, so far.

scholarly journals Reversals in Movement Direction in Locomotor Interception of Uniformly Moving Targets

2021 ◽  
Vol 12 ◽  
Author(s):  
Gwenaelle Ceyte ◽  
Remy Casanova ◽  
Reinoud J. Bootsma
Keyword(s):  
Control Strategies ◽  
Rate Of Change ◽  
Movement Direction ◽  
Moving Targets ◽  
Motion Direction ◽  
Reversal Phenomenon ◽  
Bearing Angle ◽  
Driving Task ◽  
Heading Angle ◽  
Initial Target

Here we studied how participants steer to intercept uniformly moving targets in a virtual driving task. We tested the hypothesis that locomotor interception behavior cannot fully be explained by a strategy of nulling rate of change in pertinent agent-target relations such as the target-heading angle or target’s bearing angle. In line with a previously reported observation and model simulations, we found that, under specific combinations of initial target eccentricity and target motion direction, locomotor paths revealed reversals in movement direction. This phenomenon is not compatible with unique reliance on first-order (i.e., rate-of-change based) information in the case of uniformly moving targets. We also found that, as expected, such reversals in movement direction were not observed consistently over all trials of the same experimental condition: their presence depended on the timing of the first steering action effected by the participant, with only early steering actions leading to reversals in movement direction. These particular characteristics of the direction-reversal phenomenon demonstrated here for a locomotor interception-by-steering task correspond to those reported for lateral manual interception. Together, these findings suggest that control strategies operating in manual and locomotor interception may at least share certain characteristics.

Fly photoreceptors. III. Angular sensitivity as a function of wavelength and the limits of resolution

1976 ◽  
Vol 194 (1115) ◽  
pp. 151-177 ◽  
Keyword(s):  
Lower Limit ◽  
Cross Section ◽  
Horizontal Plane ◽  
Vertical Plane ◽  
Unexpected Result ◽  
Acceptance Angle ◽  
Angular Sensitivity ◽  
Standard Methods ◽  
The Difference ◽  
Airy Disk

The angular sensitivity of single retinula cells of the eye of Calliphora and Eristalis has been measured by standard methods over the range of wavelengths that are visible to these flies. The point of using different wavelengths is to test the dependence of the angular sensitivity upon the width of the Airy disk of light which is focused on the receptors. The width of the Airy disk is determined by diffraction and proportional to wavelength. The seven best Calliphora retinula cells had a mean acceptance angle of ∆ ρ v = 1.66 ± 0.22° s. d. in the vertical plane and ∆ ρ H = 1.44 ± 0.31° s. d. in the horizontal plane. The acceptance angle is independent of wavelength, and also approaches the theoretical lower limit inferred from the width of the Airy disk at 500 nm. This unexpected result is explained optically. In the dronefly Eristalis the retinula cells with a single spectral peak near 350 nm (and therefore inferred to be cell 7 or 8) have values of ∆ ρ H = 1.16 ± 0.23° s. d. and ∆ ρ v = 1.10 ± 0.17° s. d. at 350 nm and ∆ ρ H = 1.24 ± 0.31° s. d. and ∆ ρ v = 1.19 ± 0.26° s. d. at 450 nm. Retinula cells 1-6 of Eristalis , however, have a larger ∆ ρ which is independent of wavelength. The difference in ∆ ρ between the u. v. receptors and the cells 1-6 in Eristalis is explained by the smaller rhabdomeres of the former, because the two types of receptors share a common lens. In the most distal transverse sections, rhabdomeres 1-6 of Eristalis have major and minor diameters of 1.32 ± 0.11 μm s. d. and 1.09 ± 0.06 um s. d. ( N = 12). Rhabdomere 7 has major and minor diameters of 0.74 ± 0.06 μm s. d. and 0.64 ± 0.08 μm s. d ( N = 12). The observed values of ∆ ρ for cells 1-6 are predicted from a simple theory based on the width of the Airy disk and the receptor size (Kuiper 1966) which predicts that ∆ ρ is independent of wavelength. For cell 7 an additional factor is introduced whereby there is an effect of wavelength and the cross-section of the rhabdomere is effectively reduced at longer wavelengths.

scholarly journals Analysis of Moving Chord Inclination Angles when Determining Curvature of Track Axis

2021 ◽  
pp. 92-103
Author(s):  
Wladyslaw Koc
Keyword(s):  
High Precision ◽  
Horizontal Plane ◽  
Vertical Plane ◽  
New Method ◽  
Turning Angle ◽  
Circular Arc ◽  
Inclination Angles ◽  
The Difference ◽  
Chord Method ◽  
Very High

The analysis presented in the paper explains computational issues related to the use of a new method of determining the curvature of the track axis – the so-called moving chord method. It indicates the versatility of this method – it may be used both in a horizontal and vertical plane. It also draws attention to its very high precision, as evidenced by the exemplary geometric cases under consideration. The focus here is on the computational foundations of the discussed method regarding the angles of inclination of the moving chord. It was found that for a circular arc in the horizontal plane, the inclination angles of the moving chord depend on the track turning angle, while the difference in inclination angles depends only on the radius of the arc. In the case of a circular arc in the vertical plane, the moving chord inclination angles are much smaller than in the horizontal plane, which is connected with the range of the applied radii of the arcs. As in the horizontal plane, the radius of the vertical curve is the only factor that determines the discrepancy in the inclination angles of the moving chord.

scholarly journals Dielectric anisotropy as indicator of crystal orientation fabric in Dome Fuji ice core: method and initial results

2021 ◽  
pp. 1-12
Author(s):  
Tomotaka Saruya ◽  
Shuji Fujita ◽  
Ryo Inoue
Keyword(s):  
Crystal Orientation ◽  
Horizontal Plane ◽  
Ice Core ◽  
Vertical Plane ◽  
Vertical Direction ◽  
Core Sample ◽  
Dielectric Anisotropy ◽  
Principal Axes ◽  
Polycrystalline Ice ◽  
Initial Results

Abstract Polycrystalline ice is known to exhibit macroscopic anisotropy in relative permittivity (ɛ) depending on the crystal orientation fabric (COF). Using a new system designed to measure the tensorial components of ɛ, we investigated the dielectric anisotropy (Δɛ) of a deep ice core sample obtained from Dome Fuji, East Antarctica. This technique permits the continuous nondestructive assessment of the COF in thick ice sections. Measurements of vertical prism sections along the core showed that the Δɛ values in the vertical direction increased with increasing depth, supporting previous findings of c-axis clustering around the vertical direction. Analyses of horizontal disk sections demonstrated that the magnitude of Δɛ in the horizontal plane was 10–15% of that in the vertical plane. In addition, the directions of the principal axes of tensorial ɛ in the horizontal plane corresponded to the long or short axis of the elliptically elongated single-pole maximum COF. The data confirmed that Δɛ in the vertical and horizontal planes adequately indicated the preferred orientations of the c-axes, and that Δɛ can be considered to represent a direct substitute for the normalized COF eigenvalues. This new method could be extremely useful as a means of investigating continuous and depth-dependent variations in COF.

scholarly journals A New Method for the Calculation of Energy and Power Requirements of Bucket Wheel Excavators

2019 ◽  
Vol 10 (1) ◽  
pp. 15-20
Author(s):  
József András ◽  
József Kovács ◽  
Endre András ◽  
Ildikó Kertész ◽  
Ovidiu Bogdan Tomus
Keyword(s):  
Energy Consumption ◽  
Numerical Method ◽  
Horizontal Plane ◽  
Vertical Plane ◽  
New Method ◽  
Energy Requirements ◽  
Belt Conveyor ◽  
Analytical Formulas ◽  
Power And Energy ◽  
Continuous Working

Abstract The bucket wheel excavator (BWE) is a continuous working rock harvesting device which removes the rock by means of buckets armoured with teeth, mounted on the wheel and which transfers rock on a main hauling system (generally a belt conveyor). The wheel rotates in a vertical plane and swings in the horizontal plane and raised / descended in the vertical plane by a boom. In this paper we propose a graphical-numerical method in order to calculate the power and energy requirements of the main harvesting structure (the bucket wheel) of the BWE. This approach - based on virtual models of the main working units of bucket wheel excavators and their working processes - is more convenient than those based on analytical formulas and simplification hypotheses, and leads to improved operation, reduced energy consumption, increased productivity and optimal use of available actuating power.

scholarly journals HOW TO OBTAIN A GLOBAL REFERENCE THRESHOLD IN AHP/ANP

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Claudio Garuti
Keyword(s):  
Real Life ◽  
Absolute Measurement ◽  
Threshold Value ◽  
Rate Of Change ◽  
Current Status ◽  
Medical Diagnoses ◽  
Specific Objective ◽  
Global Threshold ◽  
Disaster Assessment ◽  
The Difference

This paper has two main objectives. The first objective is to provide a mathematically grounded technique to construct local and global thresholds using the well-known rate of change method. The next objective, which is secondary, is to show the relevance and possibilities of applying the AHP/ANP in absolute measurement (AM) compared to the relative measurement (RM) mode, which is currently widely used in the AHP/ANP community. The ability to construct a global threshold would help increase the use of AHP/ANP in the AM mode (rating mode) in the AHP/ANP community. Therefore, if the first specific objective is achieved, it would facilitate reaching the second, more general objective.   For this purpose, a real-life example based on the construction of a multi-criteria index and threshold will be described. The index measures the degree of lag of a neighborhood through the Urban and Social Deterioration Index (USDI) based on an AHP risks model. The global threshold represents the tolerable lag value for the specific neighborhood. The difference or gap between the neighborhood’s current status (actual USDI value) and this threshold represents the level of neighborhood deterioration that must be addressed to close the gap from a social and urban standpoint. The global threshold value is a composition of 45 terminal criteria with their own local threshold that must be evaluated for the specific neighborhood. This example is the most recent in a large list of AHP applications in AM mode in vastly different decision making fields, such as risk disaster assessment, environmental assessment, the problem of medical diagnoses, social responsibility problems, BOCR analysis for the evolution of nuclear energy in Chile in the next 20 years and many others. (See list of projects in Appendix).

scholarly journals A clinical comparison of three aligning archwires in terms of alignment efficiency: A prospective clinical trial

2014 ◽  
Vol 85 (3) ◽  
pp. 434-439 ◽  
Author(s):  
Reem Sh. Abdelrahman ◽  
Kazem S. Al-Nimri ◽  
Emad F. Al Maaitah
Keyword(s):  
Nonparametric Test ◽  
Rate Of Change ◽  
Orthodontic Appliances ◽  
Initial Alignment ◽  
Chi Square ◽  
Fixed Appliance ◽  
Irregularity Index ◽  
Fixed Orthodontic Appliances ◽  
Wilks Lambda ◽  
The Difference

ABSTRACT Objectives:  To clinically evaluate the effectiveness of three orthodontic aligning archwires in relation to tooth alignment speed during the initial alignment stage of treatment. Materials and Methods:  A consecutive sample of 74 patients requiring lower only or upper and lower fixed orthodontic appliances were randomly allocated into three different archwires (0.014-inch superelastic nickel-titanium [NiTi], 0.014-inch thermoelastic NiTi, or 0.014-inch conventional NiTi). Good quality impressions were taken of the lower arch before archwire placement (T0) and at designated serial stages of alignment (every 2 weeks: T2, T4, T6, …, T16). The change in tooth alignment was measured in millimeters from the resultant casts using Little's irregularity index. Demographic and clinical differences among the three groups were compared with the chi-square or analysis of variance (ANOVA) test. The difference in the change of lower anterior tooth alignment over time among the three groups was explored with a Split Plot ANOVA (SPANOVA, or within- and between-groups ANOVA). The Kruskal-Wallis nonparametric test was used when data were not normally distributed. Results:  The SPANOVA and Wilks Lambda Multivariate test confirmed that the wire type had no influence on the rate of change in alignment (P  =  .98). Conclusion:  The three forms of NiTi wires were similar in terms of their alignment efficiency during the initial aligning stage of orthodontic fixed appliance therapy.

Many-legged maneuverability: dynamics of turning in hexapods

1999 ◽  
Vol 202 (12) ◽  
pp. 1603-1623 ◽  
Author(s):  
D.L. Jindrich ◽  
R.J. Full
Keyword(s):  
Horizontal Plane ◽  
Center Of Mass ◽  
Vertical Plane ◽  
Force Production ◽  
The Body ◽  
Mean Velocity ◽  
Blaberus Discoidalis ◽  
Body Design ◽  
Reaction Forces ◽  
Straight Ahead

Remarkable similarities in the vertical plane of forward motion exist among diverse legged runners. The effect of differences in posture may be reflected instead in maneuverability occurring in the horizontal plane. The maneuver we selected was turning during rapid running by the cockroach Blaberus discoidalis, a sprawled-postured arthropod. Executing a turn successfully involves at least two requirements. The animal's mean heading (the direction of the mean velocity vector of the center of mass) must be deflected, and the animal's body must rotate to keep the body axis aligned with the heading. We used two-dimensional kinematics to estimate net forces and rotational torques, and a photoelastic technique to estimate single-leg ground-reaction forces during turning. Stride frequencies and duty factors did not differ among legs during turning. The inside legs ended their steps closer to the body than during straight-ahead running, suggesting that they contributed to turning the body. However, the inside legs did not contribute forces or torques to turning the body, but actively pushed against the turn. Legs farther from the center of rotation on the outside of the turn contributed the majority of force and torque impulse which caused the body to turn. The dynamics of turning could not be predicted from kinematic measurements alone. To interpret the single-leg forces observed during turning, we have developed a general model that relates leg force production and leg position to turning performance. The model predicts that all legs could turn the body. Front legs can contribute most effectively to turning by producing forces nearly perpendicular to the heading, whereas middle and hind legs must produce additional force parallel to the heading. The force production necessary to turn required only minor alterations in the force hexapods generate during dynamically stable, straight-ahead locomotion. A consideration of maneuverability in the horizontal plane revealed that a sprawled-postured, hexapodal body design may provide exceptional performance with simplified control.

Change of Phototropic and Geotropic Signs in Daphnia Induced by Changes of Light Intensity

1930 ◽  
Vol 7 (2) ◽  
pp. 109-131 ◽  
Author(s):  
G. L. CLARKE
Keyword(s):  
Light Intensity ◽  
Latent Period ◽  
Daphnia Pulex ◽  
Great Majority ◽  
Absolute Intensity ◽  
Rate Of Change ◽  
Intensity Change ◽  
The Difference ◽  
The Individual ◽  
Secondary Signs

1. A method is described for studying the responses of Daphnia to changes of light intensity with special attention to the behaviour of the individual and to the avoidance of "shock" effects. The types of apparatus used provide for rigid control of the temperature, for illumination from any direction, and for an adjustable rate of change of the light intensity by means of a chemical rheostat. 2. The great majority of Daphnia magna and Daphnia pulex were found to be primarily negatively phototropic and positively geotropic. That is, they always exhibited those tropistic signs under constant conditions of illumination. 3. A reduction of the light intensity causes a temporary reversal of the tropism signs. The secondary signs thus produced are positive phototropism and negative geotropism. 4. The presence of both phototropic and geotropic forces is proved by experiments in which illumination is (1) from one side, (2) from beneath, and (3) from two opposing sides or from above and below simultaneously. In these tests and in others in which very slow and very fast rates of dimming are used the phototropic and geotropic forces are resolved, antagonised, and neutralised in succession. The responses of the Daphnia indicate that there are two types of animals which exhibit exactly the same tropisms, but in one type phototropism is the stronger while in the other geotropism is the stronger. 5. In this material it was found that the temporary secondary tropistic signs persisted only a few minutes while the primary signs persisted for hours, although this effect was somewhat less marked in weak light or in darkness. 6. The difference between "time-change" and "place-change" of light in tensity is pointed out. Daphnia is stimulated by both types of change if the rate of change is sufficiently great. 7. That photosensitive animals are stimulated to respond to changes in the intensity of light only and are merely orientated by the direction of the light is shown in the work of previous, investigators as well as in this paper. The rigidity of this mechanism is indicated by experiments in which the light is graded in intensity at right angles to its direction and in which the light is rendered converging and diverging by a lens. 8. Evidence is given for believing that there is no "absolute optimum" light intensity for Daphnia but that a "relative optimum" exists which is the intensity to which the animals are adapted at the moment. 9. The interval between the inception of the reduction of the light intensity and the beginning of swimming movements in response is called the latent period. The faster the rate of dimming, the shorter is the duration of the latent period. A minimum, amount of intensity change is required to produce any response, at any speed, but beyond that the slower the rate of dimming, the greater is the amount of change required and hence the lower is the absolute intensity at which the response takes place. Ordinarily, the response is maximal in respect to both rate and magnitude. 10. Fatigue will interfere with experimentation unless guarded against. 11. Specimens of Daphinia with reversed primary signs gain temporary secondary signs following an increase of light intensity; otherwise they behave like the more usual forms. 12. The possibility that the processes of adaptation in Daphnia may account for the photic responses observed is discussed. Support for this theory is derived from the fact that it is possible to dim the light over a given range at such a slow rate that no response is produced.

The Effect of Total Precipitation of Various Periods to Flow Regimes in Mountainous Catchments in Japan : Considering the Geological Characteristics of Catchments

2021 ◽  
Author(s):  
Yuka Muto ◽  
Takeyoshi Chibana ◽  
Masafumi Yamada
Keyword(s):  
Sedimentary Rocks ◽  
Correlation Coefficients ◽  
Flow Regimes ◽  
Rate Of Change ◽  
Total Precipitation ◽  
Lower Type ◽  
Geological Characteristics ◽  
Mountainous Catchments ◽  
Geological Conditions ◽  
The Difference

<p>In order to conduct an appropriate management in each catchment, it is important to understand how the difference in geological conditions affect the relationship between precipitation and flow regimes.</p><p>Considering the differences in geological characteristics of catchments, this study aims 1)to clarify the period for calculating the total precipitation that is most influential to several levels of daily flow respectively and 2)to clarify the contribution of the change in the total precipitation of ‘the most influential period’ to the change in flow.</p><p>In this study, 63 mountainous catchments (dam catchments) within the Japanese Archipelago were selected as target areas. First, the 63 catchments were divided into 4 groups according to their geological characteristics. Second, from the observed data of daily flow lasting 26 years (from 1993 to 2018), 6 types of daily flow which represent flow of different scales within a year (1, 10, 25, 50, 75, 95 percentiles of daily flow within a year) were searched. In each geological classification, correlation coefficients between each 6 type of flow and total precipitation of various periods (from 2 days to 365 days) were calculated. Finally, for each geological classification and each type of flow, single regression analyses were conducted, setting the rate of change in flow amount as the objective variable, and the rate of change in total precipitation amount of the appropriate period as the explanatory variable.</p><p>As a result, in the analysis of correlation coefficients, significant differences among different geological classifications were seen for lower type of flows but not for higher type of flows. For catchments of volcanic rocks in the Quaternary period, total precipitation of 365 days before the flow occurrence had the highest correlation coefficient with lower type of flows. On the other hand, for catchments of sedimentary rocks in the Mesozoic or Paleozoic era, the most influential period was approximately 45 days, which was the shortest.</p><p>Also, increasing trends in flow (i.e. the rate of change in flow > 1.0) during the target period were seen regardless of the geological classification or the type of flow. However, from the simple regression analysis, the significant effect of the change in precipitation to the change in flow was only seen for annual maximum flow of catchments of sedimentary rocks from the Mesozoic or Paleozoic era. Except this specific geological characteristic and flow type, there is a possibility that other conditions of the catchments (e.g. change in land use) have larger effect to the change in flow compared to the change in precipitation.</p><p>In the analyses mentioned above, the effect of snowfall is not considered. Therefore, in the presentation, the difference between snow covered regions and others are compared in addition.</p>

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