Comparison of approximate and numerical analyses of nonlinear combustion instability

At the present time, there are three general analytical techniques available to study problems of unsteady motions in rocket motors: linear stability analysis; approximate nonlinear analysis, founded on examining the behavior of coupled normal modes; and numerical calculations based on the conservation equations for one-dimensional flows. The last two yield the linear results as a limit. It is the main purpose of this paper to check the accuracy of the approximate analysis against the numerical analysis for some special cases. The results provide some justification for using the approximate analysis to study three dimensional problems

A method of eliminating hydrogen maser wall shift

Maser output frequency shift was prevented by storage bulb kept at temperature at which wall shift is zero and effects of bulb size, shape, and surface texture are eliminated. Servo system is shown, along with bidirectional counter

System automatically tunes hydrogen masers

Automatic tuning system permits frequency synchronization between two hydrogen masers. System matches spaceborne clock performance with that of ground-based clock to test red shift theory. This system, used in conjunction with radio astronomy for long-baseline interferometer experiments, serves as a tool for investigation of distant universe phenomena

Condensation and coexistence in a two-species driven model

Condensation transition in two-species driven systems in a ring geometry is studied in the case where current-density relation of a domain of particles exhibits two degenerate maxima. It is found that the two maximal current phases coexist both in the fluctuating domains of the fluid and in the condensate, when it exists. This has a profound effect on the steady state properties of the model. In particular, phase separation becomes more favorable, as compared with the case of a single maximum in the current-density relation. Moreover, a selection mechanism imposes equal currents flowing out of the condensate, resulting in a neutral fluid even when the total number of particles of the two species are not equal. In this case the particle imbalance shows up only in the condensate

Labor Market Shocks and Retirement: Do Government Programs Matter?

This paper examines how unemployment affects retirement and whether the Unemployment Insurance (UI) system and Social Security (SS) system affect how older workers respond to labor market shocks. To do so, we use pooled cross-sectional data from the March Current Population Survey (CPS) as well as March CPS files matched between one year and the next and longitudinal data from the Health and Retirement Survey (HRS). We find that downturns in the labor market increase retirement transitions. The magnitude of this effect is comparable to that associated with moderate changes in financial incentives to retire and to the threat of a health shock to which older workers are exposed. Interestingly, retirements only increase in response to an economic downturn once workers become SS-eligible, suggesting that retirement benefits may help alleviate the income loss associated with a weak labor market. We also estimate the impact of UI generosity on retirement and find little consistent evidence of an effect. This suggests that in some ways SS may serve as a more effective form of unemployment insurance for older workers than UI.