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The concept of impedance of mechanical elements is presented by the analogy to electric circuits. The impedance concept makes the whole field of circuit analysis with its highly developed circuit rules, theorems, and mathematics available for the solution of mechanical problems. Because the calculation of the impedance of most structures is very difficult, a direct measurement of impedance can simplify the problem. Several devices for this measurement are presented. Then, a computer and recorder is shown which calculates and plots impedance information as the measurement is being made. Finally, examples are presented where velocities at points on a simple structure are predicted for sinusoidal excitation and the shock-excited velocity response of a mass mounted on sponge rubber is predicted from impedance information.

Too much attention has been given to the analysis of the transient disturbances to which present day electronic gear is exposed. It does not necessarily follow that such extremely detailed examinations lead to practical engineering procedures which will produce equipment resistant to or be immune to such transient excitations. Much more attention should be given to reduce this wealth of material to a level where designers of equipment can formulate yardsticks which can be a part of the many other accepted standard procedures and which are now common practice in order to build equipment compatible with certain environments.

The performance requirements specified for an airborne weapons system are indicative of the class of desired characteristics for the proper functioning of any complex system. To achieve an integrated system with these performance capabilities requires the maximum application of system engineering. Simulation as such represents one of the basic tools available for analyzing and assessing the accuracy, stability and reliability characteristics for any complex nonlinear system. The application of simulation to the design, development, and evaluation of an airborne weapons system specifically illustrates its potentialities and effectiveness. The text to follow demonstrates, by representative examples, how simulation contributes to the analysis of complex problems inevitably present in weapons system development and also discusses the nature of the results that may be obtained.

Past experience showed that laboratory cycles available seven years ago for predicting stable pour points of engine lubricating oils did not correctly predict maximum field pour points. Additional information on factors influencing fluidity of lubricants during field exposure was necessary for lubricant development. This information was gained by the exposure of engine lubricating oils to winter temperatures at Prince George, B.C., and Fairbanks, Alaska. Variables in base oils, lubricating oil additives, and pour depressants which influence stable pour point are discussed. All components influence stable pour point. Correlation of field stable pour points with several laboratory cycles is reviewed. With the better cycles stable pour point can be predicted within ± 10°F of the maximum field stable pour point 50% to 70% of the time. Experience gained is applied to the development of lubricants of low field stable pour point.

This paper presents the results of recent field tests on passenger car motor oils to determine the lubricant factors affecting oil consumption. The lubricants covered a wide range of viscosity and viscosity index, and included a synthetic oil and twelve mineral oils having zero, low, or high V.I. improver concentrations. V.I. improvers of different types and viscosity stabilities were included. A method of predicting the oil consumption characteristics of a wide variety of oil types has been developed from these results.