scholarly journals Targetting and optomotor space in the leaf-hopper Empoasca vitis (Gothe) (Hemiptera: Cicadellidae)

1996 ◽  
Vol 199 (3) ◽  
pp. 731-740 ◽  
Author(s):  
J Brackenbury
Keyword(s):  
Vertical Axis ◽  
Spatial Integration ◽  
Image Size ◽  
Axial Resolution ◽  
Empoasca Vitis ◽  
Image Area ◽  
Intermediate Image ◽  
Vertical Bars ◽  
Jump Trajectory ◽  
Angular Coordinates

The accuracy with which the visuomotor system of Empoasca vitis can prescribe a jump trajectory towards a bright, uniformly illuminated target shape was investigated. The targets consisted of discs, rings or bars cut out of black card and mounted in front of a source of stroboscopic light diffused through translucent paper. The targets varied in size, subtending angles of 7-110 ° to the insect's eye. Target resolution was measured independently along the horizontal and vertical axes and was defined in terms of the standard deviation of the horizontal (s.d.x) or vertical (s.d.y) angular coordinates of the take-off paths measured with respect to the geometric centre of the target. In all cases involving single connected images, the point towards which jumping was directed coincided with the geometric centre of the image area (the light centroid). This meant, for example, that the insects specifically targetted the dark core of a ring of light. No formal features of the target shapes, such as light-dark boundaries, were targetted. Vertical axial resolution was independent of image size (mean s.d.y for all image sizes 6.9 °), but horizontal axial resolution only achieved this minimal value at intermediate image sizes (approximately 30-60 °). When two separate but identical target shapes (vertical bars) were presented at different horizontal separations, the dark area between them was accurately targetted up to target separations of approximately 30-50 °. At greater separations, there was an increasing tendency to target one or other of the two shapes. From these experiments it is concluded that, in the frontal visual field, spatial integration can be performed to an accuracy (as defined in these experiments) of 7 °x7 °. Performance deteriorates outside an optimal range of image sizes, and this is faithfully reflected in the decline in horizontal axial resolution when jumping. However, this decline in visual performance is not reflected in target resolution along the vertical axis because it is masked by a biomechanical constraint, i.e. the inability of the legs to set take-off angles outside a narrow range of 30-60 ° to the horizontal.

scholarly journals Evaluation of the panoramic image formation in different anatomic positions

2010 ◽  
Vol 21 (5) ◽  
pp. 458-462 ◽  
Author(s):  
Daniela Brait Silva Ladeira ◽  
Adriana Dibo da Cruz ◽  
Solange Maria de Almeida ◽  
Frab Norberto Bóscolo
Keyword(s):  
Horizontal Plane ◽  
Image Formation ◽  
Vertical Axis ◽  
Image Size ◽  
Radiographic Image ◽  
Middle Portion ◽  
Image Layer ◽  
Acrylic Plate ◽  
Recorded Data ◽  
Digital Caliper

The aim of this study was to determine size, shape and position of the image layer by evaluation of the radiographic image formation in different anatomic positions. A customized phantom was made of a rectangular acrylic plate measuring 14 cm² and 0.3 cm thick, with holes spaced 0.5 cm away and arranged in rows and columns. Each column was separately filled with 0.315 cm diameter metal spheres to acquire panoramic radiographs using the Orthopantomograph OP 100 unit. The customized phantom was placed on the mental support of the device, with its top surface kept parallel to the horizontal plane, and was radiographed at three different heights from the horizontal plane, i.e., the orbital, occlusal and mandibular symphysis levels. The images of the spheres were measured using a digital caliper to locate the image layer. The recorded data were analyzed statistically by the Student'-t test, ANOVA and Tukey' test (?=0.05). When the image size of spheres in horizontal and vertical axes were compared, statistically significant differences (p<0.05) were observed in all areas, portions of the image layer and heights of horizontal plane evaluated. In the middle portion of the image layer, differences in the image size of spheres were observed only along the horizontal axis (p<0.05), whereas no differences were observed along the vertical axis (p>0.05). The methodology used in this determined the precise size, shape and position of the image layer and differences in magnification were observed in both the horizontal and vertical axes.

scholarly journals Mechanical and mathematical modeling of the load movement on the thread wound on cylindrical drum with movable axis

2021 ◽  
Vol 102 (2) ◽  
pp. 54-63
Author(s):  
Serhii Podliesnyi ◽  
Mykola Dorokhov ◽  
Oleksandr Stadnyk ◽  
Yurii Yerfort
Keyword(s):  
Mathematical Model ◽  
Mechanical System ◽  
Degrees Of Freedom ◽  
Nonlinear Dynamical Systems ◽  
Lagrange Equation ◽  
Vertical Axis ◽  
Material Point ◽  
Nonlinear Dynamical ◽  
Load Movement ◽  
Angular Coordinates

A mechanical system, where the load in the form of material point is suspended on inextensible thread screwed on the rotating cylindrical drum, but the drum is connected to the boom rotating around fixed horizontal axis is considered. Using the Lagrange equation of the second kind, a mathematical model of the motion of the mechanical system is obtained. The system has three degrees of freedom, two of which are cylindrical. The investigation of the system motion is carried out using computer technology. As a result, the dependences of linear and angular coordinates and velocities in time at different values of the output data for two main modes of the system operation, namely – under the conditions of lifting and lowering the load are obtained. Appropriate graphs are constructed, including the trajectories of the cargo motion. The mathematical model takes into account nonlinearities of the system and allows you to find the amount of tension of the hoisting rope at any time. The analysis showed that vertical oscillations occur twice as fast as horizontal ones. The phase portrait of the generalized coordinate (angle of the rope with the vertical axis) is the focus, which is untwisted when lifting due to nonlinearity in the system, and when the load moves down, the focus, which twists and approaches the mathematical pendulum is obtained. The obtained results can be used in modeling of controlled pendulum motions for different mechanical systems. The methodology and program are recommended to the students and graduate students in terms of learning the principles of construction and analysis of complex nonlinear dynamical systems.

scholarly journals ABOUT THE ANTHROPOMORPHIC ROBOTS

Engevista ◽  
2014 ◽  
Vol 17 (1) ◽  
pp. 1
Author(s):  
Florian Ion Tiberiu Petrescu ◽  
Relly Victoria Virgil Petrescu
Keyword(s):  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Kinematic Chain ◽  
Vertical Axis ◽  
Basic Structure ◽  
Original Method ◽  
Base System ◽  
Spatial Integration ◽  
The Matrix ◽  
Basic Movement

The paper presents an original geometrical and kinematic method for the study of geometry and determining positions of a MP-3R structure of the anthropomorphic robots. It presents shortly the MP-3R direct and inverse kinematics, the inverse kinematics being solved by an original exactly method. One presents shortly an original method to solve the robot inverse kinematics exemplified at the 3R-Robots (MP-3R). The system which must be solved has three equations and three independent parameters to determine. Constructive basis is represented by a robot with three degrees of freedom (a robot with three axes of rotation).  If we study (analyze) an anthropomorphic robot with three axes of rotation (which represents the main movements, absolutely necessary), we already have a base system, on which we can then add other movements (secondary, additional). Calculations were arranged and in the matrix form. The most commonly used serial structures over the last 20 or 30 years are those of type 3R, 4R, 5R, 6R, having as constituents essential basic kinematic chain 3R, robot anthropomorphic (RRR), where main rotation around a vertical axis, causes the construction. It can thus passes from the study spatial movement, which is more difficult, to the study motion plane, basic movement, for all the robots and fillers serial movements of rotation. Moving flat, horizontal or vertical, shall be undertaken far more easily than the spatial integration with the convenience simple in the space of which it is part. We will exemplify the basic structure existing in a few serial platforms of rotation, these being the most generalized (more widespread) at the present time. In this work will be pursued and the direct and inverse kinematics of these mechanical systems. It can make the transition from 3R systems-level 2R and vice versa.

Spatial Representations as an Emergent Feature of Perceptual Processing

2010 ◽  
Vol 24 (3) ◽  
pp. 161-172 ◽  
Author(s):  
Edmund Wascher ◽  
C. Beste
Keyword(s):  
Common Ground ◽  
Event Related Potentials ◽  
Vertical Axis ◽  
Relevant Information ◽  
Sources Of Information ◽  
Integrated Network ◽  
Perceptual Maps ◽  
Emergent Feature ◽  
Related Potentials ◽  
Selection Of

Spatial selection of relevant information has been proposed to reflect an emergent feature of stimulus processing within an integrated network of perceptual areas. Stimulus-based and intention-based sources of information might converge in a common stage when spatial maps are generated. This approach appears to be inconsistent with the assumption of distinct mechanisms for stimulus-driven and top-down controlled attention. In two experiments, the common ground of stimulus-driven and intention-based attention was tested by means of event-related potentials (ERPs) in the human EEG. In both experiments, the processing of a single transient was compared to the selection of a physically comparable stimulus among distractors. While single transients evoked a spatially sensitive N1, the extraction of relevant information out of a more complex display was reflected in an N2pc. The high similarity of the spatial portion of these two components (Experiment 1), and the replication of this finding for the vertical axis (Experiment 2) indicate that these two ERP components might both reflect the spatial representation of relevant information as derived from the organization of perceptual maps, just at different points in time.

The Palestinian Refugee Camps In Jordan: Between National Identity and Socio-economic Integration

2004 ◽  
Vol 2 (2) ◽  
pp. 198-221 ◽  
Author(s):  
Ala Al-Hamarneh
Keyword(s):  
United Nations ◽  
Collective Memory ◽  
Economic Integration ◽  
Refugee Camps ◽  
Spatial Integration ◽  
Political Activities ◽  
Cultural Traditions ◽  
The Past ◽  
Distinct Character ◽  
Palestinian Refugee

At least 50 per cent of the population of Jordan is of Palestinian origin. Some 20 per cent of the registered refugees live in ten internationally organized camps, and another 20 per cent in four locally organized camps and numerous informal camps. The camps organized by the United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNRWA) play a major role in keeping Palestinian identity alive. That identity reflects the refugees' rich cultural traditions, political activities, as well as their collective memory, and the distinct character of each camp. Over the past two decades integration of the refugees within Jordanian society has increased. This paper analyses the transformation of the identity of the camp dwellers, as well as their spatial integration in Jordan, and other historical and contemporary factors contributing to this transformation.

Calculating the aerodynamics of vertical axis wind turbines

2012 ◽  
Vol 34 (3) ◽  
pp. 169-184 ◽  
Author(s):  
Hoang Thi Bich Ngoc
Keyword(s):  
Wind Turbine ◽  
Incidence Angle ◽  
Vertical Axis ◽  
Rotor Blades ◽  
Vertical Axis Wind Turbine ◽  
Horizontal Axis Wind Turbine ◽  
Velocity Triangle ◽  
Relationship Of ◽  
The Relationship

Vertical axis wind turbine technology has been applied last years, very long after horizontal axis wind turbine technology. Aerodynamic problems of vertical axis wind machines are discussible. An important problem is the determination of the incidence law in the interaction between wind and rotor blades. The focus of the work is to establish equations of the incidence depending on the blade azimuth, and to solve them. From these results, aerodynamic torques and power can be calculated. The incidence angle is a parameter of velocity triangle, and both the factors depend not only on the blade azimuth but also on the ratio of rotational speed and horizontal speed. The built computational program allows theoretically selecting the relationship of geometric parameters of wind turbine in accordance with requirements on power, wind speed and installation conditions.

Selection of Airfoils for Vertical Axis Wind Turbines for Low Speed, Low Altitude Regions of Central India

2017 ◽  
Vol 7 (11) ◽  
pp. 113
Author(s):  
Abhineet Singh ◽  
Sonali Mitra ◽  
S.V.H. Nagendra ◽  
Pragyan Jain
Keyword(s):  
Numerical Analysis ◽  
Central India ◽  
Vertical Axis ◽  
College Campus ◽  
Low Speed ◽  
Vertical Axis Wind Turbines ◽  
Low Altitude ◽  
Naca 0015 ◽  
Naca 0012 ◽  
Selection Of

The present paper deals with the selection of airfoil profile for VAWTs which is to be installed in the college campus, located in Central India region. Both experimental and numerical analysis he been carried out for the three selected airfoils, NACA 0012, NACA 0015 & S2027. The results show a good correlation with the existing literature. Airfoil profile S2027 has been chosen which best suits our condition. 

Design and Analysis of Vertical Axis Wind Turbine

2017 ◽  
Author(s):  
Prof. R.K. Bhoyar ◽  
Prof. S.J. Bhadang ◽  
Prof. N.Z. Adakane ◽  
Prof. N.D. Pachkawade
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine
Sign in / Sign up

Export Citation Format

Share Document