A Theoretical Approach to the Shift Mechanics of Rubber Belt Variators

2008 ◽  
Vol 130 (12) ◽  
Author(s):  
Francesco Sorge
Keyword(s):  
Numerical Solutions ◽  
Control Volume ◽  
Mass Conservation ◽  
Theoretical Description ◽  
The Other ◽  
Control Surface ◽  
Speed Ratio ◽  
Rubber Belt ◽  
Total Mass Flux ◽  
Inertia Forces

This paper proposes a theoretical description of the mechanical behavior of rubber belt variators during the speed ratio shift. Comparing with the steady operation, the mass conservation of the belt is completely reformulated considering an elementary dihedral control volume between two planes through the pulley axis and balancing the inside mass variation with the total mass flux through the control surface. On the other hand, the belt equilibrium conditions are similar to the steady case, as the inertia forces due to the shifting motion are negligible with respect to the other forces. Assuming a one-dimensional belt model, it is shown that adhesive regions may appear inside the arc of contact, where the belt sticks to the pulley flanges along spiral-shaped paths. It is demonstrated that this type of contact may occur only for the closing pulleys, differently from the steady drives and from the opening pulleys, where only quasiadhesive internal subregions may be observed at most, where the sliding velocity turns out to be quite small along a more or less extended portion of the arc of contact. Numerical solutions are calculated for all types of conditions, and their characteristics are widely described.

Approximate Closed-Form Solutions for the Shift Mechanics of Rubber Belt Variators

2009 ◽  
Author(s):  
Marco Cammalleri ◽  
Francesco Sorge
Keyword(s):  
Closed Form ◽  
Mass Conservation ◽  
Experimental Tests ◽  
Speed Ratio ◽  
Equilibrium Equations ◽  
Closed Form Solutions ◽  
Rubber Belt ◽  
Linear Differential ◽  
The Mathematical Model ◽  
Transport Theorem

The mechanical behavior of V-belt variators during the speed ratio shift is different from the steady operation as a gross radial motion of the belt is superimposed to the circumferential motion. The theoretical analysis involves equilibrium equations similar to the steady case, but requires a re-formulation of the mass conservation condition making use of the Reynolds transport theorem. The mathematical model of the belt-pulley coupling implies the repeated numerical solution of a strongly non-linear differential system. Nevertheless, an attentive observation of the numerical diagrams suggests simple and useful closed-form approximations for the four possible working modes of any pulley, opening/closing, driver/driven, whose validity ranges over most practical cases. The present analysis focuses on the development of such simplified solutions, succeeding in an excellent matching with the numerical plots, and on the comparison of the theory with some experimental tests on a motorcycle variator, revealing a very good agreement.

Influences of Iteration Details on Flow Continuities of Numerical solutions to Isothermal Elastohydrodynamic Lubrication with Micro-Cavitations

2020 ◽  
pp. 1-28
Author(s):  
Shuangbiao Liu ◽  
Liangwei Qiu ◽  
Zhijian Wang ◽  
Xiaoyang Chen
Keyword(s):  
Numerical Solutions ◽  
Elastohydrodynamic Lubrication ◽  
Iteration Process ◽  
Mass Conservation ◽  
The Other ◽  
Flow Curves ◽  
Line Contacts ◽  
Film Content ◽  
Relaxation Factors ◽  
First Time

Abstract Studying elastohydrodynamic lubrication (EHL) of line contacts involving micro-cavitations, this paper exams various numerical solutions with a focus of their explicit flow continuities from inlet to exit. For the first time, influences of relaxation details, error controls, differential schemes, and mesh densities on flow continuity in EHL are revealed in a systemic fashion. Furthermore, hybrid relaxation-factors are introduced, the line relaxation is enabled with earlier boundary condition enforcement, and a typical iteration process is updated with a three-in-one iteration control. Such a process is further integrated with two different starvation/cavitation treatments: one explicitly adjusts reformation locations, and the other uses a fractional film content parameter to adjust the Couette term originated by Bayada et al.. The mass conservation results for problems with multiple micro-cavitations occurring inside the lubrication region are compared and flow curves clearly demonstrate satisfactory continuities. These insights are beneficial for EHL simulations.

scholarly journals An augmented Lagrangian method for solving total variation (TV)-based image registration model

2020 ◽  
Vol 14 ◽  
pp. 174830262097353
Author(s):  
Noppadol Chumchob ◽  
Ke Chen
Keyword(s):  
Image Registration ◽  
Augmented Lagrangian ◽  
Numerical Solutions ◽  
Augmented Lagrangian Method ◽  
Closed Form Solution ◽  
Numerical Algorithms ◽  
Lagrangian Method ◽  
Form Solution ◽  
The Other ◽  
Other Hand

Variational methods for image registration basically involve a regularizer to ensure that the resulting well-posed problem admits a solution. Different choices of regularizers lead to different deformations. On one hand, the conventional regularizers, such as the elastic, diffusion and curvature regularizers, are able to generate globally smooth deformations and generally useful for many applications. On the other hand, these regularizers become poor in some applications where discontinuities or steep gradients in the deformations are required. As is well-known, the total (TV) variation regularizer is more appropriate to preserve discontinuities of the deformations. However, it is difficult in developing an efficient numerical method to ensure that numerical solutions satisfy this requirement because of the non-differentiability and non-linearity of the TV regularizer. In this work we focus on computational challenges arising in approximately solving TV-based image registration model. Motivated by many efficient numerical algorithms in image restoration, we propose to use augmented Lagrangian method (ALM). At each iteration, the computation of our ALM requires to solve two subproblems. On one hand for the first subproblem, it is impossible to obtain exact solution. On the other hand for the second subproblem, it has a closed-form solution. To this end, we propose an efficient nonlinear multigrid (NMG) method to obtain an approximate solution to the first subproblem. Numerical results on real medical images not only confirm that our proposed ALM is more computationally efficient than some existing methods, but also that the proposed ALM delivers the accurate registration results with the desired property of the constructed deformations in a reasonable number of iterations.

Branchial cleft and pouch anomalies

1992 ◽  
Vol 106 (2) ◽  
pp. 137-143 ◽  
Author(s):  
G. R. Ford ◽  
A. Balakrishnan ◽  
J. N. G. Evans ◽  
C. M. Bailey
Keyword(s):  
Recurrent Infection ◽  
Theoretical Description ◽  
The Other ◽  
Unexpected Finding ◽  
Neck Swelling ◽  
Complete Excision ◽  
Delay In Diagnosis ◽  
Branchial Cleft Anomalies ◽  
Branchial Cleft ◽  
Sick Children

AbstractWe present a retrospective study of 106 patients with branchial cleft and pouch anomalies who presented to the Hospital for Sick Children between 1948 and 1990. The relevant embryology of the branchial apparatus is summarized and a theoretical description of individual anomalies given.Second branchial cleft sinuses were the most common anomalies, and the majority were managed simply, with adequate excision and a low recurrence rate. Five cases of first branchial cleft anomalies are presented, emphasizing the delay in diagnosis, the need for complete excision to prevent recurrence, and for a parotidectomy incision to protect the facial nerve from damage. The two third branchial pouch anomalies presented with a cystic neck swelling, one with recurrent infection and discharge, and the other with stridor. In both, the diagnosis was made at operation. The single fourth branchial pouch cyst was an unexpected finding in a patient with stridor.

Aeroelastic Problems in connection with High-Speed Flight

1956 ◽  
Vol 60 (547) ◽  
pp. 459-475 ◽  
Author(s):  
E. G. Broadbent
Keyword(s):  
Mach Number ◽  
High Speed ◽  
The Other ◽  
Control Surface ◽  
The Past ◽  
Other Hand ◽  
Aerodynamic Derivatives ◽  
Mach Numbers ◽  
The One

SummaryA review is given of developments in the field of aeroelasticity during the past ten years. The effect of steadily increasing Mach number has been two-fold: on the one hand the aerodynamic derivatives have changed, and in some cases brought new problems, and on the other hand the design for higher Mach numbers has led to thinner aerofoils and more slender fuselages for which the required stiffness is more difficult to provide. Both these aspects are discussed, and various methods of attack on the problems are considered. The relative merits of stiffness, damping and massbalance for the prevention of control surface flutter are discussed. A brief mention is made of the recent problems of damage from jet efflux and of the possible aeroelastic effects of kinetic heating.

scholarly journals ODREĐIVANJE TERMIČKIH VELIČINA KOD PRAVOLINIJSKOG KLIZNOG LEŽIŠTA NA BAZI DISIPACIONE FUNKCIJE

2021 ◽  
Author(s):  
Mirko Radic ◽  
◽  
Duško Kostic ◽  
Branko Pejovic ◽  
Srđan Jovic ◽  
...  
Keyword(s):  
Continuity Equation ◽  
Energy Equation ◽  
Control Volume ◽  
Mass Conservation ◽  
Dissipation Function ◽  
Second Law ◽  
Specific Calculation ◽  
Influence Of Temperature ◽  
Technical Practice ◽  
Two Dimensional Flow

In the first part of the paper, the continuity equation in the boundary layer for stationary two-dimensional flow is derived on the basis of the law of mass conservation. After that, using Newton's second law for control volume, the equation for the momentum was derived. Using the derived equations, the analysis was performed with respect to the influence of temperature. After that, on the basis of the energy balance, an energy equation was derived in which a viscous dissipation function was introduced, which enabled a wider application. At the end of the paper, the derived equations were applied to a specific calculation example from technical practice in the calculation of thermal quantities in a rectilinear sliding bearing, which was the aim of the work

scholarly journals Theoretical Description for Chlorantraniliprole Electrochemical Determination, Assisted by Squaraine Dye Nano Ag2O2 Composite

2020 ◽  
Vol 11 (2) ◽  
pp. 9278-9284
Keyword(s):  
Mathematical Model ◽  
Reaction Mechanism ◽  
Bifurcation Analysis ◽  
Electrochemical Determination ◽  
Theoretical Description ◽  
The Other ◽  
Linear Stability Theory ◽  
Oxide Nanoparticles ◽  
Monotonic Instability ◽  
Squaraine Dye

The theoretical description for the chlorantraniliprole electrochemical determination, assisted by the hybrid composite of squaraine dye with Ag2O2 nanoparticles, has been described. The correspondent reaction mechanism has been proposed, and the correspondent mathematical model has been developed and analyzed by means of linear stability theory and bifurcation analysis. It has been shown that the chlorantraniliprole electrochemical anodic determination on high potential may be efficiently provided by silver (I, III) oxide nanoparticles, stabilized by the squaraine dye. On the other hand, the oscillatory and monotonic instability is also possible, being caused by DEL influences of the electrochemical stage.

Design and Analysis of Steering Mechanism for Small Tracked Vehicle

2014 ◽  
Vol 701-702 ◽  
pp. 659-665
Author(s):  
Fa Liang Zhou ◽  
Xiao Jun Xu ◽  
Hao Yue Zhang
Keyword(s):  
The Other ◽  
Transmission Ratio ◽  
Tracked Vehicle ◽  
Tracked Vehicles ◽  
Steering Mechanism ◽  
Rubber Belt

The steering mechanism of tracked vehicles is complicated and large, which is an obstacle for its miniaturization. According to the theory of rubber-belt CVTs, a new kind of steering mechanism for small Tracked vehicle is designed. The mechanism consists of two symmetrical-layout rubber-belt CVTs. A sliding part for steering is designed, which can slide axially to make the transmission ratio of one transmission increase while the other reduces, so that the tracked vehicle turns. The steering motion is calculated and its motion discipline is founded. The steering sensitivity and steering smoothness are analyzed, and its steering performance is evaluated.

Adaptive Numerical Modeling of Engineering Problems Using Hierarchical Fup Basis Functions and Control Volume IsoGeometric Analysis

2021 ◽  
Author(s):  
◽  
Grgo Kamber ◽  
Keyword(s):  
Isogeometric Analysis ◽  
Numerical Solutions ◽  
Control Volume ◽  
Spatial Scales ◽  
Basis Functions ◽  
Approximation Properties ◽  
Unified Framework ◽  
B Splines ◽  
Engineering Problems ◽  
Resolution Level

The main objective of this thesis is to utilize the powerful approximation properties of Fup basis functions for numerical solutions of engineering problems with highly localized steep gradients while controlling spurious numerical oscillations and describing different spatial scales. The concept of isogeometric analysis (IGA) is presented as a unified framework for multiscale representation of the geometry and solution. This fundamentally high-order approach enables the description of all fields as continuous and smooth functions by using a linear combination of spline basis functions. Classical IGA usually employs Galerkin or collocation approach using B-splines or NURBS as basis functions. However, in this thesis, a third concept in the form of control volume isogeometric analysis (CV-IGA) is used with Fup basis functions which represent infinitely smooth splines. Novel hierarchical Fup (HF) basis functions is constructed, enabling a local hp-refinement such that they can replace certain basis functions at one resolution level with new basis functions at the next resolution level that have a smaller length of the compact support (h-refinement), but also higher order (p-refinement). This hp-refinement property enables spectral convergence which is significant improvement in comparison to the hierarchical truncated B-splines which enable h-refinement and polynomial convergence. Thus, in domain zones with larger gradients, the algorithm uses smaller local spatial scales, while in other region, larger spatial scales are used, controlling the numerical error by the prescribed accuracy. The efficiency and accuracy of the adaptive algorithm is verified with some classic 1D and 2D benchmark test cases with application to the engineering problems with highly localized steep gradients and advection-dominated problems.

Intermittent Viewing in a Study of Visual Prediction

1972 ◽  
Vol 34 (1) ◽  
pp. 223-226 ◽  
Author(s):  
Hugh C. Foot
Keyword(s):  
The Other ◽  
Speed Ratio ◽  
Point Of Coincidence ◽  
Continuous Display ◽  
The One

43 undergraduates made predictions of the point of coincidence of 2 pointers rotating at different rates, the trailing one closing on the leading one in the speed ratio of 3:2. During the viewing period, prior to prediction, pointer rotation was displayed intermittently, with variations in the display to no-display ratio. Results did not support the hypothesis that intermittent displays would produce more accurate predictions than a continuous display, as a consequence of the greater apparent opportunity for feedback provided by the intermittent displays. Intermittent displays resulted in magnitude of error similar to that produced by a continuous display. Ss' tendencies to over- or underestimate the point of coincidence appeared to be related to their estimates of the relative rates of travel by the two pointers. This suggested that the large consistent errors made by many Ss might be due to a generalized, and often erroneous, assumption concerning the rate of gain of the one pointer on the other

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