The financing problem of the Social Security system has captured great attention. The 2005 OASDI Trustees' Report projects that the combined OASI and DI Trust Funds will become exhausted in 2041. Solutions to this problem include raising the covered-earnings' cap, encouraging people to work longer, or making people postpone their participation in the Old Age program. This dissertation addresses these issues respectively in three essays.
My first essay examines the impact of the increase in the covered-earnings' cap from the 1965, 1972 and 1977 Amendments on the gross wage and employment. An increase in the percentage of workers earning above the pre-law-change cap resulted in a decline in the post-reform gross wage for the three Amendments. I find no employment effect for the 1965 Amendments but negative employment effects for the 1972 and 1977 Amendments. However, the employment effects are sensitive to the specification forms.
In the second essay, I use the geographic variation in manufacturing concentration to examine the impact of de-industrialization on older workers' labor force participation. My results show that a one percentage point decrease in local earnings due to de-industrialization raised older workers' labor force non-participation rate by 0.78, and the probability of leaving the labor force by 0.80. In addition, the labor force participation of older workers fell more than twice as fast in the industrial cities as in the non-industrial cities between 1980 and 1990, a period of rapid decline in manufacturing.
The third essay exploits shocks to the Appalachian coal mining and shocks to US manufacturing to examine the impact of local labor market conditions on Social Security. I find that a 10 percent increase in the growth rate of earnings induced by the coal shocks or the manufacturing shocks resulted in a 1.3 percent decline in the growth rate of Old Age expenditure and a 0.9 percent decrease in the growth rate of recipients. In addition, a one percentage point decrease in local earnings caused by de-industrialization raised the Social Security take-up rate by 0.77, and the probability of participating in Social Security by 0.63.
This paper introduces the meanings of harshness and the NVH phenomena in vehicle, and summarizes the means of CAE simulation and evaluation, used to study the vehicle NVH performance.The application of the NVH performance study in the course of vehicle design is introduced emphatically, which includes FSI analysis and the building of combination model of rigid body and flexible body. With an example of the high speed shimmy in a car, the application of the NVH performance study to the improvement of vehicle comfort is discussed.Finally,the significance of vehicle NVH performance study and the important role plays in vehicle design is summarized and the prospect is forecasted.