Analysis of Wheel/Rail Contact Geometry on Railroad Turnout Using Longitudinal Interpolation of Rail Profiles

2010 ◽  
Vol 6 (2) ◽  
Author(s):  
Hiroyuki Sugiyama ◽  
Yoshimitsu Tanii ◽  
Ryosuke Matsumura
Keyword(s):  
Point Contact ◽  
Numerical Procedure ◽  
Contact Geometry ◽  
Cross Sectional ◽  
Numerical Examples ◽  
Contact Points ◽  
The Given

In this investigation, a numerical procedure that can be used for the analysis of wheel/rail two-point contact geometries in turnout sections is developed. In turnout section, the tongue rail changes its shape along the track. Cross-sectional shapes of the tongue rail, therefore, need to be generated by interpolations along the track and these profiles are used to determine the location of contact points for the given location of wheelset. Several numerical examples are presented in order to demonstrate the use of the procedure developed in this investigation and the effect of wheel profiles on contact geometry in turnout section is discussed.

Analysis of Wheel/Rail Contact Geometry in Turnout Section

2009 ◽  
Author(s):  
Hiroyuki Sugiyama ◽  
Yoshimitsu Tanii ◽  
Yoshihiro Suda
Keyword(s):  
Point Contact ◽  
Numerical Procedure ◽  
Contact Geometry ◽  
Cross Sectional ◽  
Numerical Examples ◽  
Contact Points ◽  
Contact Configuration

In this investigation, a numerical procedure that can be used for the analysis of wheel/rail two-point contact geometries in turnout sections is developed. In turnout section, the tongue rail changes its shape along the track. Cross-sectional shapes of the tongue rail, therefore, need to be generated by interpolations along the rail and these profiles are used to determine the location of contact points for given location of wheelset along the track trajectory. Numerical examples of wheel/rail contact in point section are presented in order to demonstrate the use of the procedure developed in this investigation and the effect of wheel profiles on the contact configuration in turnout section is discussed.

Wheel/Rail Two-Point Contact Geometry With Back-of-Flange Contact

2007 ◽  
Author(s):  
Hiroyuki Sugiyama ◽  
Yoshihiro Suda
Keyword(s):  
Dimensional Analysis ◽  
Three Dimensional ◽  
Point Contact ◽  
Numerical Procedure ◽  
Contact Geometry ◽  
Light Rail ◽  
Contact Algorithm ◽  
Rail Vehicle ◽  
Contact Points ◽  
Contact Formulation

In this investigation, a numerical procedure that can be used for the three-dimensional analysis of wheel and rail contact geometry is developed using the constraint contact formulation. The locations of contact points are determined for given lateral and yaw displacements of a wheelset when one-point contact is considered for each wheel, while these two displacements are no longer independent when the two-point contact occurs. A systematic procedure for predicting the flange as well as the back-of-flange contact points is developed and used for the two-point contact analysis of wheel and rail. Numerical results that involve tread, flange, and back-of-flange contacts are presented in order to demonstrate the use of the contact algorithm developed in this investigation. In particular, the back-of-flange contact is discussed for assessing contact configurations of wheel and grooved rail in Light Rail Vehicle (LRV) applications.

Wheel∕Rail Two-Point Contact Geometry With Back-of-Flange Contact

2008 ◽  
Vol 4 (1) ◽  
Author(s):  
Hiroyuki Sugiyama ◽  
Yoshihiro Suda
Keyword(s):  
Point Contact ◽  
Numerical Procedure ◽  
Contact Geometry ◽  
Light Rail ◽  
Contact Algorithm ◽  
Systematic Procedure ◽  
Rail Vehicle ◽  
Contact Points ◽  
Contact Formulation ◽  
Geometry Analysis

In this investigation, a numerical procedure that can be used for the analysis of a wheel and rail contact geometry is developed using the constraint contact formulation. The locations of contact points are determined for given lateral and yaw displacements of a wheelset when one-point contact is considered for each wheel, while these two displacements are no longer independent when the two-point contact occurs. A systematic procedure for predicting the flange, as well as the back-of-flange contact points, is developed and used for the two-point contact geometry analysis of a wheel and rail. Numerical results that involve tread, flange, and back-of-flange contacts are presented in order to demonstrate the use of the contact algorithm developed in this investigation. In particular, the back-of-flange contact is discussed for assessing contact configurations of a wheel and a grooved rail in light rail vehicle applications.

scholarly journals Two matrix methods for solution of nonlinear and linear Lane-Emden type equations with mixed condition by operational matrix

2015 ◽  
Vol 4 (3) ◽  
pp. 420 ◽  
Author(s):  
Behrooz Basirat ◽  
Mohammad Amin Shahdadi
Keyword(s):  
Bernstein Polynomials ◽  
Operational Matrix ◽  
Numerical Procedure ◽  
Operational Matrices ◽  
Algebraic Equations ◽  
Mixed Condition ◽  
Matrix Methods ◽  
Numerical Examples ◽  
Linear Algebraic Equations ◽  
The Given

<p>The aim of this article is to present an efficient numerical procedure for solving Lane-Emden type equations. We present two practical matrix method for solving Lane-Emden type equations with mixed conditions by Bernstein polynomials operational matrices (BPOMs) on interval [<em>a; b</em>]. This methods transforms Lane-Emden type equations and the given conditions into matrix equation which corresponds to a system of linear algebraic equations. We also give some numerical examples to demonstrate the efficiency and validity of the operational matrices for solving Lane-Emden type equations (LEEs).</p>

Force Optimization Approaches for Common Anthropomorphic Grasps

2016 ◽  
Author(s):  
Aimee Cloutier ◽  
James Yang
Keyword(s):  
Point Contact ◽  
Contact Forces ◽  
Applied Force ◽  
Linear Matrix ◽  
Human Hand ◽  
Numerical Examples ◽  
Contact Points ◽  
Force Optimization ◽  
Grasping Forces ◽  
Grasping Force

A smart choice of contact forces between robotic grasping devices and objects is important for achieving a balanced grasp. Too little applied force may cause an object to slip or be dropped, and too much applied force may cause damage to delicate objects. Prior methods of grasping force optimization in literature have mostly assumed grasp only at the fingertips but have rarely considered how the whole hand grasps more common to anthropomorphic hands affect the optimization of grasping forces. Further, although numerical examples of grasping force optimization methods are routinely provided, it is often difficult to compare the performance of separate methods when they are evaluated using different parameters, such as the type of grasping device, the object grasped, and the contact model, among other factors. This paper presents three optimization approaches (linear, nonlinear, and nonlinear with linear matrix inequality (LMI) friction constraints) which are compared for an anthropomorphic hand. Numerical examples are provided for three types of grasp commonly performed by the human hand (cylindrical grasp, tip grasp, and tripod grasp) using both soft finger contact and point contact with friction models. Contact points between the hand and the object are predetermined. Results are compared based on their accuracy, computational efficiency, and other various benefits and drawbacks unique to each method. Future work will extend the problem of grasping force optimization to include consideration for variable forces and object manipulation.

Three-Point Contact Study of a Wheelset and Rails

2016 ◽  
Author(s):  
Behrooz Fallahi ◽  
Chao Pan
Keyword(s):  
Coordinate System ◽  
Point Contact ◽  
Algebraic Equations ◽  
Numerical Examples ◽  
Block Matrices ◽  
Constraint Equations ◽  
Contact Points ◽  
Set Up

Three-point contact occurs in curving and transfer of a wheelset over switches and turnouts. In this study, an approach is presented that enforces three-point contact between a wheelset and a rail. This is accomplished by placing the wheelset over the track by setting the wheelset position parameters. Then, the location of all common normal are computed. Next, three common normal with shortest length are used to set up the non-penetrating constraint equations in track coordinate system. This led to nine algebraic equations whose Jacobean can be represented by block matrices. A Newton iterate based on these block matrices are used to compute the location of the three contact points. Several numerical examples are presented to verify the accuracy of the approach.

Difference Schemes for Nonlinear BVPS on the Semiaxis

2007 ◽  
Vol 7 (1) ◽  
pp. 25-47 ◽  
Author(s):  
I.P. Gavrilyuk ◽  
M. Hermann ◽  
M.V. Kutniv ◽  
V.L. Makarov
Keyword(s):  
Differential Equation ◽  
Exact Solution ◽  
Boundary Value Problem ◽  
Difference Scheme ◽  
Adaptive Algorithm ◽  
Order Differential Equation ◽  
Constructive Method ◽  
Numerical Examples ◽  
Exact Difference ◽  
The Given

Abstract The scalar boundary value problem (BVP) for a nonlinear second order differential equation on the semiaxis is considered. Under some natural assumptions it is shown that on an arbitrary finite grid there exists a unique three-point exact difference scheme (EDS), i.e., a difference scheme whose solution coincides with the projection of the exact solution of the given differential equation onto the underlying grid. A constructive method is proposed to derive from the EDS a so-called truncated difference scheme (n-TDS) of rank n, where n is a freely selectable natural number. The n-TDS is the basis for a new adaptive algorithm which has all the advantages known from the modern IVP-solvers. Numerical examples are given which illustrate the theorems presented in the paper and demonstrate the reliability of the new algorithm.

scholarly journals Electromigration-induced directional steps towards the formation of single atomic Ag contacts

2020 ◽  
Vol 11 ◽  
pp. 680-687
Author(s):  
Atasi Chatterjee ◽  
Christoph Tegenkamp ◽  
Herbert Pfnür
Keyword(s):  
Fourier Transforms ◽  
Single Point ◽  
Point Contact ◽  
Single Atom ◽  
Point Contacts ◽  
Cross Sectional ◽  
Shell Effects ◽  
Theoretical Approaches ◽  
Average Grain Size ◽  
Thinning Process

Even though there have been many experimental attempts and theoretical approaches to understand the process of electromigration (EM), it has not been quantitatively understood for ultrathin structures and at grain boundaries. Nevertheless, we showed recently that it can be used reliably for the formation of single atomic point contacts after careful pre-structuring of the initial Ag nanostructures. The process of formation of nanocontacts by EM down to a single-atom point contact was investigated for ultrathin (5 nm) Ag structures at 100 K by measuring the conductance as a function of the time during EM. In this paper, we compare the process of thinning by EM of structures with constrictions below the average grain size of Ag layers (15 nm) with that of structures with much larger initial constrictions of around 150 nm having multiple grains at the centre constriction prior to the formation of a point contact. Even though clear morphological differences exist between both types of structures, quantized conductance plateaus showing the formation of single point contacts have been observed for both. Here we put emphasis on the thinning process by EM, just before a point contact is formed. To understand this thinning process, the semi-classical regime before the contact reaches the quantum regime was analyzed in detail. For this purpose, we used experimental conductance histograms in the range between 2G 0 and 15G 0 and their corresponding Fourier transforms (FTs). The FT analysis of the conductance histograms exhibits a clear preference for thinning along the [100] direction. Using well-established models, both atom-by-atom steps and ranges of stability, presumably caused by electronic shell effects, can be discriminated. Although the directional motion of atoms during EM leads to specific properties such as the instabilities mentioned, similarities to mechanically opened contacts with respect to cross-sectional stability were found.

scholarly journals Numerical method of identification of an unknown source term in a heat equation

2002 ◽  
Vol 8 (2) ◽  
pp. 161-168 ◽  
Author(s):  
Afet Golayoğlu Fatullayev
Keyword(s):  
Inverse Problem ◽  
Heat Equation ◽  
Numerical Method ◽  
Minimization Problem ◽  
Unknown Function ◽  
Source Term ◽  
Numerical Procedure ◽  
Numerical Examples ◽  
Unknown Source

A numerical procedure for an inverse problem of identification of an unknown source in a heat equation is presented. Approach of proposed method is to approximate unknown function by polygons linear pieces which are determined consecutively from the solution of minimization problem based on the overspecified data. Numerical examples are presented.

Multi-Agent Form Closure Capture of a Generic 2D Polygonal Object Based on Projective Path Planning

2006 ◽  
Author(s):  
Pankaj Sharma ◽  
Anupam Saxena ◽  
Ashish Dutta
Keyword(s):  
Path Planning ◽  
Contact Point ◽  
Point Contact ◽  
Object Boundary ◽  
Actual Object ◽  
Contact Points ◽  
Correct Orientation ◽  
Novel Approach ◽  
Form Closure ◽  
Multi Agent

The study of multi-agent capture and manipulation of an object has been an area of active interest for many researchers. This paper presents a novel approach using Genetic Algorithm to determine the optimal contact points and the total number of agents (mobile robots) required to capture a stationary generic 2D polygonal object. After the goal points are determined the agents then reach their respective goals using a decentralized projective path planning algorithm. Form closure of the object is obtained using the concept of accessibility angle. The object boundary is first expanded and the robots reach the expanded object goal points and then converge on the actual object. This ensures that the agents reach the actual goal points at the same time and have the correct orientation. Frictionless point contact between the object and robots is assumed. The shape of the robot is considered a circle such that it can only apply force in outward radial direction from its center and along the normal to the object boundary at the contact point. Simulations results are presented that prove the effectiveness of the proposed method.

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