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Effect of inclination on film boiling
The object of this investigation was to determine the effect of inclination on the heat transfer for film pool boiling. The test plate used as the heater was made of Inconel-600 and heated electrically. Liquid nitrogen at atmospheric pressure was used as the test fluid. The heater was oriented at various angles from the horizontal position with the heater surface facing both upward and downward and the heat transfer coefficient was determined for each angle over temperature differences ranging from 450ºF to 750ºF. As the heater angle was increased from 0º (horizontal) to 90º (vertical), the heat transfer coefficient increased both for the heater surface facing upward and for the surface facing downward but the magnitude of the change was different --Abstract, page ii
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Three essays in econometrics
textIn this dissertation, I would like to consider the efficient estimation of
various models in the presence of heteroskedasticity of unknown form. The first
essay focuses on mean sqaure errors comparison of linear regression model of
hetetroskedasticity with unknown form. I compare higher order properties of
the efficient estimators which include the GMM-type Cragg estimator, FGLS
based on series and kernel estimations. The comparison is to calculate the
approximate mean square errors of estimators using the Nagar type stochastic
expansion.
In the second essay, I consider the efficient estimation of partial linear
regression model under heteroskedastictiy with unknown form. I propose an
efficient estimator and prove it achieves Chamberlain’s (1992) semi-parametric
efficiency bound. The new estimator I propose has the same first order asymptotic properties as Li’s (2000) estimator. My estimator has the potential advantage of analyzing the higher order asymptotics. The third essay considers the two-step series estimation method for
generated regressors problem in context of semiparametric regression model
under heteroskedastictiy of unknown form. I establish the root-n consistency
and asymptotic normality results of the two-step series estimators. Compared
to the double kernel estimator introduced by Stengos and Yan (2001), my
estimator has some computational advantage and is more accurate in the sense
of the asymptotic variance. Simulation results show that the two-step series
estimator outperforms the double kernel estimator in terms of mean absolute
bias and mean square error.
The estimators considered in three essay involve the problem of choosing smoothing parameters. Therefore, I also demonstrate how to pick optimal
smoothing parameters in each essay.Economic
An Intelligent Auxiliary Vacuum Brake System
The purpose of this paper focuses on designing an intelligent, compact, reliable, and robust auxiliary vacuum brake system (VBS) with Kalman filter and self-diagnosis scheme. All of the circuit elements in the designed system are integrated into one programmable system-on-chip (PSoC) with entire computational algorithms implemented by software. In this system, three main goals are achieved: (a) Kalman filter and hysteresis controller algorithms are employed within PSoC chip by software to surpass the noises and disturbances from hostile surrounding in a vehicle. (b) Self-diagnosis scheme is employed to identify any breakdown element of the auxiliary vacuum brake system. (c) Power MOSFET is utilized to implement PWM pump control and compared with relay control. More accurate vacuum pressure control has been accomplished as well as power energy saving. In the end, a prototype has been built and tested to confirm all of the performances claimed above
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