The steady state and dynamic characteristics including whirl instability of waterlubricated journal bearings having three axial grooves are obtained theoretically. The Reynolds equation is solved numerically by the ®nite difference method satisfying the appropriate boundary conditions. The dynamic behaviour in terms of stiffness and damping coef®cients of ®lm and stability are found using a ®rst-order perturbation method. It has been shown that both load capacity and stability improve when smaller groove angles are used. NOTATION C radial clearance (m) D diameter of the bearing (m) D rr , D ff , D rf , D fr damping coef®cient (N s/m) D rr , D ff , D rf , D fr non-dimensional damping coef®cient, D ijˆDij Co=…LDp s † e eccentricity (m)

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A numerical solution of an elastohydrodynamic lubrication (EHL) contact between two long, rough surface cylinders is obtained. A theoretical solution of pressure distribution, elastohydrodynamic load, and film thickness for given speeds and for lubricants with pressure-dependent viscosity, material properties of cylinders, and surface roughness parameters is made by simultaneous solution of an elasticity equation and the Reynolds equation for two partially lubricated rough surfaces. The pressure due to asperity contact is calculated by assuming a Gaussian distribution of surface irregularities. The elastic deformation is found from hydrodynamic and contact pressures by using plane strain analysis. The effect of surface roughness on EHL loads, speeds, and central film thicknesses is studied. The results indicate that for a constant central film thickness (1) increasing the surface roughness decreases the EHL load and (2) there is little variation in minimum film thickness as the surface roughness is increased.

This paper describes the design and the VLSI implementation of a novel architecture that performs image rotation in real time. In order to improve throughput, we divide an image-frame into a number of windows. The rotation of each window-center as well as the final displacement of individual pixels within a window is then calculated. A CORDIC-based scheme is used to compute the displacement of a pixel. Our architectural design is incorporated into a chip that has been laid out using VTI (VLSI Technology Inc.) tools obeying the 1.5 μm SCMOS design rules. The chip owes its high processing capability to a combination of pipelining and parallel-processing techniques. For a clock frequency greater than 10.6 MHz, we can perform the rotation of a 512×512 gray-level digital image at the rate of 30 frames per second. The chip utilizes around 35,000 transistors and has an estimated silicon area of 211 mils×276 mils.

The stiffness and damping characteristics of isothermal, elastohydrodynamically lubricated point contact problems are evaluated numerically considering the surface roughness effect and variation in viscosity with pressure. A set of equations under steady-state and dynamic conditions is derived from the classical Reynolds equation using the linear perturbation method. The elasticity equation and steady-state Reynolds equation are solved simultaneously using the finite difference method with the successive over-relaxation scheme, whereas the dynamic pressures are found after solving the set of perturbed equations using the previously obtained steady-state pressures. The load capacity is obtained from the steady-state pressure distribution. The stiffness and damping coefficients of the contact are determined using the dynamic pressures. Then the overall stiffness and damping matrices of the ball bearing are obtained from the load distribution, coordinate transformation, and compatibility relations.

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This i n v e s t i g a t i o n deals w i t h t h e s t a b i l i t y c h a r a c t e r i s t i c s o f o i lj o u r n a l bearings, i n c l u d i n g t h e e f f e c t of e l a s t i c d i s t o r t i o n s i n t h e b e a r i n g l i n e r . Graphical r e s u l t s a r e presented f o r ( 1 ) steady-state load, ( 2 ) s t i f f n e s s and damping c o e f f i c i e n t s , and ( 3 ) t h e s t a b i l i t y . These r e s u l t s a r e a J given f o r v a r i o u s slenderness r a t i o s , e c c e n t r i c i t y r a t i o s , and e l a s t i c i t y parameters. The l u b r i c a n t i s f i r s t assumed t o be isoviscous. The a n a l y s i s i s then extended t o t h e case o f a pressure-dependent v i s c o s i t y . I t has been found t h a t s t a b i l i t y decreases w i t h increase o f t h e e l a s t i c i t y parameter oft h e bearing l i n e r f o r h e a v i l y loaded bearings.