What Can Be Learned from Smeets and Brenner's Model about the Control of Grasping?

Motor Control ◽  
1999 ◽  
Vol 3 (3) ◽  
pp. 302-306 ◽  
Author(s):  
Bert Steenbergen
Keyword(s):  
Boundary Condition ◽  
Velocity Profile ◽  
Visual Feedback ◽  
Basic Function ◽  
Present Form ◽  
Object Properties ◽  
Transport Component ◽  
Proposed Model

The present reaction on the paper of Smeets and Brenner focuses on two premises of their proposed model The first is that grasping is nothing more than pointing with two fingers. It is argued that this assumption cannot be upheld in light of the differences between both actions with respect to neuromuscular structures, muscular innervation, use of visual feedback, and basic function The second premise of the model is that the velocity profile of the transport component is symmetrical and independent of intrinsic object properties. It is shown that the symmetrical velocity profile represents a boundary condition and is influenced by intrinsic object properties. Given these concerns, it is doubtful that the model in its present form will add much to our understanding of the control of grasping.

scholarly journals Nonlinear Dynamic Characteristic Analysis of a Landing String in Deepwater Riserless Drilling

2018 ◽  
Vol 2018 ◽  
pp. 1-17
Author(s):  
Jun Liu ◽  
Hongliang Zhao ◽  
Simon X. Yang ◽  
Qingyou Liu ◽  
Guorong Wang
Keyword(s):  
Boundary Condition ◽  
Dynamic Model ◽  
Marine Environment ◽  
Lower Boundary ◽  
Dynamic Responses ◽  
Characteristic Analysis ◽  
Lower Boundary Condition ◽  
Response Characteristics ◽  
Proposed Model ◽  
Nonlinear Dynamic Characteristic

The landing string is an important component of deepwater riserless drilling systems. Determination of the dynamic characteristics of the landing string plays an essential role in its design for ensuring its safe operation. In this paper, a dynamic model is developed to investigate the dynamic response characteristics of a landing string, where a landing string in a marine environment is modeled as a flexible slender tube undergoing coupled transverse and axial motions. The heaving motion of the drilling platform is taken as the upper boundary condition and the motion of the drilling bit caused by the interaction between the rock and the bit as the lower boundary condition. A semiempirical Morison equation is used to simulate the effect of the load imposed by the marine environment. The dynamic model, which is nonlinearly coupled and multibody, is discretized by a finite element method and solved by the Newmark technique. Using the proposed model, the dynamic responses of the displacement, axial force, and moment in the landing string are investigated in detail to find out the influences of driving depth of surface catheter, platform motion, bit movement, and marine environment on the dynamical characteristics of the landing string.

Three Dimensional Simulation of Blood Flow in the Small Arteries of a Truncated Vascular System With Three Levels of Bifurcation

2014 ◽  
Author(s):  
Kamil Kahveci ◽  
Bryan R. Becker
Keyword(s):  
Boundary Condition ◽  
Blood Flow ◽  
Blood Vessel ◽  
Velocity Profile ◽  
Flow Velocity ◽  
Blood Flow Velocity ◽  
Vascular System ◽  
Three Dimensional ◽  
Simulation Software ◽  
Small Arteries

Three dimensional blood flow in a truncated vascular system is investigated numerically using a commercially available finite element analysis and simulation software. The vascular system considered in this study has three levels of symmetric bifurcation. Geometric parameters for daughter vessels, such as their diameters and their angles of bifurcation, are specified according to Murray’s law based on the principle of minimum work. The ratio of blood vessel length to diameter is based upon experimental data found in the literature. An experimentally obtained velocity profile, available in the literature, is used as the inlet boundary condition. An outflow boundary model, consisting of a contraction tube to represent the pressure drop of the small arteries, arterioles, and capillaries that would follow the truncated vascular system, is used to specify the boundary condition at the eight outlets. The results show that although the blood flow velocity experiences a sudden decrease after the bifurcation points due to the higher total cross-sectional area of the daughter vessels as compared to the parent vessel, this decrease in velocity is partially recovered due to the tapering of the blood vessels as they approach the next bifurcation point. The results also show that the secondary flow which is typical after the bifurcation of large arteries does not develop after the bifurcation of small arteries due to the presence of laminar blood flow with very low Reynolds number in the small arteries. The numerical model yields pressure distributions and pressure drops along the vascular system that agree quite well with the physiological data found in the literature. Finally, the results show that, immediately following a bifurcation, the blood flow velocity profile is not symmetrical about the longitudinal axes of blood vessel. However, symmetry is recovered as the blood flow proceeds down the vessel.

scholarly journals Young children do not require perceptual-motor feedback to solve Aesop’s Fable tasks

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3484 ◽  
Author(s):  
Rachael Miller ◽  
Sarah A. Jelbert ◽  
Elsa Loissel ◽  
Alex H. Taylor ◽  
Nicola S. Clayton
Keyword(s):  
Young Children ◽  
Water Level ◽  
Visual Feedback ◽  
Forced Choice ◽  
Water Levels ◽  
Current Experiment ◽  
Water Displacement ◽  
Tube Size ◽  
Causal Understanding ◽  
Object Properties

Aesop’s Fable tasks—in which subjects drop objects into a water-filled tube to raise the water level and obtain out-of-reach floating rewards —have been used to test for causal understanding of water displacement in both young children and non-human animals. However, a number of alternative explanations for success on these tasks have yet to be ruled out. One hypothesis is that subjects may respond to perceptual-motor feedback: repeating those actions that bring the reward incrementally closer. Here, we devised a novel, forced-choice version of the Aesop’s Fable task to assess whether subjects can solve water displacement tasks when this type of feedback is removed. Subjects had to select only one set of objects, or one type of tube, into which all objects were dropped at once, and the effect the objects had on the water level was visually concealed. In the current experiment, fifty-five 5–9 year old children were tested in six different conditions in which we either varied object properties (floating vs. sinking, hollow vs. solid, large vs. small and too large vs. small objects), the water level (high vs. low) and/or the tube size (narrow vs. wide). We found that children aged 8–9 years old were able to solve most of the water displacement tasks on their first trial, without any opportunity for feedback, suggesting that they mentally simulated the results of their actions before making a choice. Children aged 5–7 years solved two conditions on their first trial (large vs. small objects and high- vs. low-water levels), and learnt to solve most of the remaining conditions over five trials. The developmental pattern shown here is comparable to previous studies using the standard Aesop’s Fable task, where eight year olds are typically successful from their first trial and 5–7 year olds learn to pass over five trials. Thus, our results indicate that children do not depend on perceptual-motor feedback to solve these water displacement tasks. The forced-choice paradigm we describe could be used comparatively to test whether or not non-human animals require visual feedback to solve water displacement tasks.

An Artificial Intelligent Centered Object Inspection System Using Crucial Images

2018 ◽  
Vol 5 (1) ◽  
pp. 44-57 ◽  
Author(s):  
Santosh Kumar Sahoo ◽  
B. B. Choudhury
Keyword(s):  
Principal Component ◽  
Cuckoo Search ◽  
Basic Function ◽  
Least Square ◽  
Support Vector ◽  
Inspection System ◽  
Bench Mark ◽  
Test Functions ◽  
Proposed Model ◽  
Object Inspection

This article proposes a unique optimization algorithm like Adaptive Cuckoo Search (AdCS) algorithm followed by an Intrinsic Discriminant Analysis (IDA) to design an intelligent object classifier for inspection of defective object like bottle in a manufacturing unit. By using this methodology the response time is very faster than the other techniques. The projected scheme is authenticated using different bench mark test functions along with an effective inspection procedure for identification of bottle by using AdCS, Principal-Component-Analysis (PCA) and IDA. Due to this the projected procedures terms as PCA+IDA for dimension reduction in addition to this AdCS-IDA for classification or identification of defective bottles. The analyzed response obtained from by an application of AdCS algorithm followed by IDA and compared to other algorithm like Least-Square-Support-Vector-Machine (LSSVM), Linear Kernel Radial-Basic-Function (RBF) to the proposed model, the earlier applied scheme reveals the remarkable performance.

Turbulent Flow Using a Modified V2f Turbulence Model

2004 ◽  
Author(s):  
Hanif Montazeri ◽  
Siamak Kazemzadeh Hannani ◽  
Bijan Farhanieh
Keyword(s):  
Boundary Condition ◽  
Turbulence Model ◽  
Flow Problem ◽  
Two Dimensional ◽  
Convergence Problem ◽  
New Model ◽  
Step Flow ◽  
Wall Boundary Condition ◽  
Proposed Model ◽  
Accuracy Of Results

An improved version of the V2f turbulence model has been examined in this paper. The objective was to overcome the convergence problem encountered in the original V2f model. The convergence problem is due to the commonly-used wall boundary condition, which therefore has been modified in the proposed model. To test the soundness of the new model, several two-dimensional cases such as Poiseuille flow, channel flow, and backward-step flow has been analyzed and the results are compared with the standard k-ε model, DNS, and in case of the backward flow problem, also with the original V2f model. Based on the comparison, the new model presents a promising approach both with respect to convergence as well as the accuracy of results.

scholarly journals Analytical Solution of Tank Drainage for Electrically Conducting Power Law Fluid

2018 ◽  
Author(s):  
Saeed Islam ◽  
Kamran Nazir Memon ◽  
Abdul Majeed Siddiqui ◽  
Syed Feroz Shah
Keyword(s):  
Analytical Solution ◽  
Velocity Profile ◽  
Power Law ◽  
Analytic Solution ◽  
Fluid Model ◽  
Power Law Fluid ◽  
Special Effects ◽  
Electrically Conducting ◽  
Proposed Model ◽  
Drainage Problem

This paper investigates the tank drainage problem of an isothermal, unsteady, incompressible electrically conducting Power law fluid. Analytic solution have been obtained from governing continuity and momentum equations subject to appropriate boundary conditions by using Perturbation method. The Power law fluid model solution without MHD is retrieved from this proposed model on substitution . Declaration on behalf of velocity profile, volume flux, average velocity, connection of time with respect to length of the tank and requirement of time for whole drainage of fluid are acquired. Special effects of numerous emerging parameter’s on velocity profile vz and depth of the fluid in the tank are graphically presented. Keywords: Tank drainage, Power law MHD fluid, Analytical solution.

A Methodology for Geometry Generation of the Lower Conductive Zone of the Lung Airways and Simulation by Intermediate Boundary Conditions

2012 ◽  
Author(s):  
Ana F. Tena ◽  
Pere Casan ◽  
Raúl Barrio ◽  
Alberto Marcos ◽  
Jorge Parrondo
Keyword(s):  
Boundary Condition ◽  
Velocity Profile ◽  
Boundary Conditions ◽  
Human Lung ◽  
Time Profile ◽  
General Methodology ◽  
Numerical Predictions ◽  
Conductive Zone ◽  
Lung Airways ◽  
Good Agreement

This paper presents a general methodology for the development and simulation of a human lung between scales 0–16. The methodology is based on the simulation of only one of the two possible branches at each bronchiole. The operation of the truncated branches is included by means of a user-defined function. This function prescribes the velocity profile calculated for the active branches in the truncated ones in order to make the hydraulic losses equal between them. This procedure was tested between 0 and 7th generation by imposing the time profile of a real forced spirometry test in the trachea as boundary condition. The test showed a very good agreement between the numerical predictions and the spirometry data.

scholarly journals Application of Daftardar Jafari Method to First Grade MHD Squeezing Fluid Flow in a Porous Medium with Slip Boundary Condition

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Inayat Ullah ◽  
M. T. Rahim ◽  
Hamid Khan
Keyword(s):  
Boundary Condition ◽  
Porous Medium ◽  
Velocity Profile ◽  
Nonlinear Boundary ◽  
Slip Boundary Condition ◽  
First Grade ◽  
Squeezing Flow ◽  
Parallel Plates ◽  
Governing Equations ◽  
Slip Boundary

In the present work, in the presence of magnetic field and with slip boundary condition, squeezing flow of a Newtonian fluid in a porous medium between two large parallel plates is investigated. The governing equations are transformed to a single nonlinear boundary value problem. Daftardar Jafari Method (DJM) is used to solve the problem in order to obtain the velocity profile of the fluid. By using residual of the problem, the validity of solution is established. The velocity profile is argued through graphs for various values of parameters.

Numerical study on the rotating electro-osmotic flow of third grade fluid with slip boundary condition

2020 ◽  
Vol 75 (7) ◽  
pp. 649-655
Author(s):  
Juan Song ◽  
Shaowei Wang ◽  
Moli Zhao ◽  
Ning Li
Keyword(s):  
Boundary Condition ◽  
Velocity Profile ◽  
Slip Boundary Condition ◽  
Third Grade ◽  
Parallel Plates ◽  
Third Grade Fluid ◽  
Osmotic Flow ◽  
Slip Boundary ◽  
Grade Fluid ◽  
Electro Osmotic Flow

AbstractConsidering the slip boundary condition, the rotating electro-osmotic flow of a third grade fluid in a channel formed by two parallel plates is investigated in the present study. The charge distribution is treated with the Debye–Hückel approximation analytically. Based on the finite difference method, the velocity profile for rotating electro-osmotic flow of third grade fluid is obtained numerically. It is shown that the non-Newtonian parameter of third grade fluid and the velocity slip factor play the important roles for the rotating electro-osmotic flow. The increasing non-Newtonian parameter slows down the flow and decreases the velocity magnitude, and the increasing slip parameter β has the similar influence on the velocity profile. Furthermore, the effect of the inclusion of third grade on the velocity profile is more conspicuous in the area near the walls.

scholarly journals Adjoint-based Calibration of Inlet Boundary Condition for Atmospheric CFD Solvers

2019 ◽  
Author(s):  
Siamak Akbarzadeh ◽  
Hassan Kassem ◽  
Renko Buhr ◽  
Gerald Steinfeld ◽  
Bernhard Stoevesandt
Keyword(s):  
Boundary Layer ◽  
Boundary Condition ◽  
Velocity Profile ◽  
Calibration Function ◽  
Cfd Simulations ◽  
Inlet Velocity ◽  
Numerical Studies ◽  
Interior Domain ◽  
Continuous Adjoint ◽  
Inlet Boundary Condition

Abstract. A continuous adjoint solver is developed for optimization of the inlet velocity profile boundary condition for CFD simulations of the neutral atmospheric boundary layer (ABL). The adjoint solver uses interior domain wind speed observations to compute the gradient of a calibration function with respect to inlet velocity components and wind direction. The solver has been implemented in the open source CFD package OpenFOAM. The sensitivities computed by the newly developed adjoint solver are validated against the second order finite-difference method. Furthermore, the DAKOTA optimization package is coupled with OpenFOAM, and a number of numerical studies are carried out including the calibration of the inlet velocity profile of a 3-D complex domain.

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