A completely general solution is obtained whereby the elastic compliances of a system of any number of ball and radial roller bearings under any system of loads can be determined. Elastic yielding of the shaft and supporting structure are considered as well as centrifugal and gyroscopic loading of the rolling elements under high-speed operation. The solution defines the loading and attitude of each rolling element in each bearing of the system as well as the displacement of each inner ring with respect to its outer ring. For ball bearings the precise location of the load paths in each raceway are found. Life estimates can be more accurately made since the fatigue effects can be evaluated over known paths in the raceways. The solution, which is accomplished numerically by iterative techniques, has been programmed for an IBM-704 digital computer.

In modern high-speed ball bearings the pressure areas, which result from elastic deformations at the ball-race contacts, are appreciably curved and interfacial slip can occur at most points within the pressure areas. These slippages give rise to friction forces acting on the ball which are held in equilibrium by reactions from the races and the inertia effects of the motion of the ball. A method is derived for determining the motion of the ball and sliding friction in a high-speed, angular-contact ball bearing under thrust load in terms of the inertia effects on the ball and the frictional resistances resulting from interfacial slip at the contact areas. Possible elastic compliance at the interface, hysteresis, and dynamical perturbations of ball motion are neglected. The solution of eight, simultaneous equations involving double integrals for which closed-form solutions cannot be found is required. A solution for a particular case requires the services of a high-speed computer. For the case where gyroscopic effects on the ball can be neglected, certain simplifications and assumptions can be made which enable the solution of a particular problem using conventional computation means.

We present three cases of multiple interatrial communications to illustrate the extended use of the Amplatzer septal occluder and to highlight procedural techniques. The first case demonstrates how a single device can be used to close two adjacent defects. It is important to balloon size both defects and to note if balloon occlusion of one defect closes the other and vice versa. The second case demonstrates closure of multiple atrial septal defects using two devices. The technique needed to obtain an "interleaved" position of the two devices is detailed. This technique allows for a lower profile that reduces stress on the devices and surrounding structures and may decrease the risk of thromboembolism and device embolization. The third case describes device closure of a residual defect adjacent to a previous device implanted at an earlier sitting. In this situation, an overlapping position without the option for "interleaving" is inevitable.

Enhanced Hall-effect mobilities have been measured in epitaxial (100)-oriented multilayer n-type Si/Si1−xGex films grown on single-crystal Si substrates by chemical vapor deposition. Mobilities from ∼20 to 40% higher than that of epitaxial Si layers and ∼100% higher than that of epitaxial SiGe layers on Si were measured for the doping range ∼8×1015–∼1017 cm−3. The mobilities of multilayer Si/SiGe films approach that of single-crystal Si films at ∼2×1017 cm−3. No mobility enhancement was observed in multilayer p-type (100) films and n-type (111)-oriented films. Experimental studies included the effects upon film properties of layer composition, total film thickness, doping concentrations, layer thicknesses, and growth temperature.

Conventional calculations of ball and roller bearing carrying capacity and fatigue life assume that the raceway bodies are rigid structures and that all elastic deformation occurs at the rolling elements’ contact with the raceways. In many instances, and particularly with aircraft applications, the bearing rings and their supports cannot be considered rigid. One such application is the planet gear in a transmission. This report develops a theory whereby the effects of the elastic distortions of the outer race of a rolling-element bearing on the internal load distribution and fatigue life of the bearing can be considered. The theory has been programmed for a high-speed, digital computer. An example of calculation for a planet gear roller bearing whose outer race is integral with the gear and of relatively thin section is given. The distortions of the flexible outer ring cause a significantly lower bearing fatigue life (L10) than would occur if the outer ring were rigid and considering a practical range of bearing diametral clearances. Mr. Jones developed the theoretical analysis for this paper and Mr. Harris provided the programming and the experimental data.