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The purpose of this dissertation is to explore the relationship between fertility rates and the economy in Venezuela. In particular, it looks at the extreme fluctuations in oil revenues, Venezuela's main source of income, in the 1970s and their impact on fertility. It uses the 1998 National Survey of Population and Family collected in Venezuela by The Central Office of Statistics and Information to estimate a Poisson model of total fertility by union cohort and to empirically investigate changes in childbearing patterns. The results show that compared to the 1967-1968 union cohort, all subsequent union cohorts decline in total fertility in the first 14 years after entering the first union. This finding raises the possibility that the period fertility rate stall and reversal of the 1970s are not associated with rises in total fertility. Further, the simple two period model of fertility timing developed for this study illustrates how females may change their fertility timing by responding to temporary changes in income, either through changes in wages or changes in the amount of transfers. Also, the duration analysis presents differences in childbearing patterns where the boom cohort seems to be at a higher risk of an additional child for lower parities, but at a lower risk for higher parities when compared to the bust cohort. These differences seem to remain even after controlling for individual characteristics or secular changes between the two cohorts. This study is important, because it highlights how sharp and short changes in economic conditions faced by a Venezuelan household induce a change in the timing of birth, thereby creating unexpected moves in the period fertility rates. Understanding the source of these moves can help to plan for them in the future. / Ph. D.

Shock-shock interactions are among the most basic gas-dynamic problem, and are almost unavoidable in any high speed light, where shock waves generating from different sources crosses each other paths. These interactions when present very close to the solid surface lead to very high pressure and thermal loads on the surface. The related practical problem is that experienced at the cowl lip of a scramjet engine, where the interfering shock waves leads to high heat transfer rates which may also lead to the damage of the material. The classification by Edney (1968) on the shock-shock interaction patterns based on the visualization has since then served the basis for such studies. Though the problem of high heating on the surface in the vicinity of the shock-shock interactions has been studied at length at supersonic Mach numbers, the study on the topic at the hypersonic Mach numbers is little sparse. Even in the studies at hypersonic Mach numbers, the high speeds are not simulated, which is the measure of the kinetic energy of the ow. Very few experimental studies have addressed this problem by simulating the energy content of the ow. Also, some of the numerical studies on the shock-shock interactions suggest the presence of unsteadiness in the shock-shock interaction patterns as observed by Edney (1968), though this observation is not made very clearly in the experimental studies undertaken so far. In the present study, experiments are carried out in a conventional shock tunnel at Mach number of 5.62 (total enthalpy of 1.07 MJ/kg; freestream velocity of 1361 m/s), with the objective of mapping the surface pressure distribution and surface convective heat transfer rate distribution on the hemispherical body in the presence of the shock-shock interactions. A shock generator which is basically a wedge of angle = 25 , is placed at some dis-dance in front of the hemispherical body such that the planar oblique shock wave from the shock generator hits the bow shock wave in front of the hemi-spherical body. The relative distance between the wedge tip and the nose of the hemispherical body is allowed to change in di erent experiments to capture the whole realm of shock-shock interaction by making the planar oblique shock wave interact with the bow shock wave at different locations along its trajectory. The study results in a bulk of data for the surface pressure and heat transfer rates which were obtained by placing 5 kulites pressure transducers, 1 PCB pressure transducer and 21 platinum thin lm gauges along the surface of the hemispherical body in a plane normal to the freestream velocity direction. Along with the measurement of the surface pressure and the surface heat transfer rates, the schlieren visualization is carried out to capture the shock waves, expansion fans, slip lines, present in a certain shock-shock interaction pattern and the measured values were correlated with the captured schlieren images to evaluate the ow build up and steady and useful test time thereby helping in understanding the ow physics in the presence of the shock-shock interactions. From the present study it has been observed that in the presence of Edney Type-I and Edney Type-II interaction, the heat transfer rates on the hemi-spherical body are symmetrical about the centerline of the body, with the peak heating at the centerline which drops towards the shoulder. For Edney Type-III, Edney Type-IV, Edney Type-V and Edney Type-VI interaction pattern, the distribution in not symmetrical and shifts in peak heat transfer rates being on the side of the hemispherical from which planar oblique shock wave is incident. Also, it is observed that for the interactions which appear within the sonic circle, Edney Type-III and Edney Type-IV, the heat transfer rates observe an unsteadiness, such that the gauges located close to the interaction region experiencing varying heat transfer rates during the useful test time of the shock tunnel. Few experiments were conducted at Mach 8.36 (total enthalpy of 1.29 MJ/kg; freestream velocity of 1555.25 m/s) and Mach 10.14 (total enthalpy of 2.67 MJ/kg; freestream velocity of 2258.51 m/s) for the con gurations representing Edney Type-III interaction pattern to further evaluate the unsteady nature observed at Mach 5.62 ows. The unsteadiness was evident in both the cases. It is realized that the short test times in the shock tunnels pose a constraint in the study of unsteady flow fields, and the use of tailored mode operation of shock tunnel can alleviate this constraint. Also, limited number of experiments in the present study, which are carried out in a Free Piston Shock Tunnel, helps to understand the need to conduct such study in high enthalpy test conditions.

Shock Boundary Layer Interactions (SBLIs) and shock-shock interactions are some of the most fundamental problems in high speed aerodynamics. These interactions are of particular importance in scramjet intakes at hypersonic speeds. In hypersonic own with strong SBLI accompanied by own separation, large separation bubbles can form due to high impinging shock strengths. While experiments involving large separation lengths for the impinging shock boundary layer interactions near sharp leading edge are well documented in the literature, only few investigations on the effect of leading edge bluntness on the interactions are studied. In the present study, experiments were carried out to study the role of leading edge bluntness on the impinging shock boundary layer interactions. An oblique shock generated by a wedge (wedge angle 31 degrees) is made to impinge on a at plate (length 200 mm) over which a boundary layer develops. Different leading edge inserts were used on a at plate to get either a sharp or a blunt (radii from 2 to 8 mm) leading edge. The position of the at plate was moved horizontally with respect to the wedge to vary the shock impingement location relative to the leading edge. Experiments were carried out at two freestream conditions - Mach 5.88 (total enthalpy of 1.26 MJ/kg and freestream Reynolds number of 3.85 million per meter) and Mach 8.54 (total enthalpy of 1.85 MJ/kg and freestream Reynolds number of 1.41 million per meter). The various features of the interaction along with different parameters were obtained from schlieren visualizations and surface pressure measurements. The schlieren visualization was used to obtain the separation length, while the reattachment pressure was obtained from the surface pressure distribution. From the present experimental study, a reduction in separation length was observed with an increase in leading edge bluntness. It was also seen that the sharp leading edge had the maximum separation length. Correlations for the separation length and the reattachment pressure have been proposed for these experimental conditions. Numerical simulations were also carried out using commercial software and they had a qualitative agreement with the experiments.

This thesis aims to study the macroeconomic performance of China. China has been experiencing rapid economic growth and it has been changing gradually from a planned to a market economy since it initiated the well known “open door policy” combined with a “coastal development strategy” in 1978. However, rapid growth has occurred on the background of increasing regional disparity. Meanwhile, unemployment has increased significantly during last two decades, and has become one of the most pressing problems of the Chinese economy today. Moreover, another major challenge facing the Chinese economy is how to deal with various shocks, and to ensure the sustainability and balance of economic growth in the face of the increasing economic uncertainties associated with its deep reform and integration into the world trade and financial system. Based on the above concerns and literature review, this study, firstly, uses an augmented Solow-Swan model of Mankiw, Romer and Weil (1992) to assess the role FDI plays in underlying regional differences in economic growth across Chinese provinces over the reform period 1978-2008. My analysis indicates that the augmented Solow growth model appears to provide a good description of regional growth patterns in China over the period 1978-2008 and the data display conditional convergence. After controlling for FDI and other determinants of growth, provinces that were initially poor tend to grow faster and the evidence in favour of conditional convergence becomes even stronger after splitting the data into subsamples. I then focus on the study of the relationship between unemployment and growth at both national level and regional level in order to find out how unemployment affects China’s economic growth and economic reform progress overall. I find that Okun’s relationship does not hold in China universally and, furthermore, the nature of the observed relationship has changed during the transition progress. I argue that there are hump shaped relationships both between growth and unemployment and between the speed of transition and unemployment in China. The results are consistent with several theoretical and empirical studies in the literature. Finally, structural VAR methodology pioneered by Bayoumi and Eichengreen (1993) is used to identify and decompose supply and demand shocks to two variables, (the log of) output (annual real GDP) and (the log of) prices (annual GDP deflator). I then compute and discuss the correlation of such shocks across provinces and show how it has evolved over the four main sub-periods of China’s history. Moreover, I investigate which factors contribute to economic integration or divergence in the Chinese economy.

A thesis submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in ful lment of the requirements for the degree of Doctor of Philosophy. Johannesburg, May 2017 / Shock{waves (shocks) exist in various shapes; restricted to two dimensions some examples are planar, cylindrical, parabolic and elliptical. However, most shock{wave research has been focussed mostly on plane shocks. In this research, the scope is expanded to cylindrical shock{wave segments where a plane shock can be viewed as a cylindrical shock segment (referred to as a cylindrical shock) with a large radius of curvature; with this view, the expectations are that cylindrical and plane shocks behave similarly although with quantitative di erences. Whereas plane shocks have constant orientation, constant strength and can be imagined to extend unbounded, cylindrical shock segments demand that both ends be bound; this leads to spatial constraints, shock strength varying with respect to radius and shock orientation being non-constant. Three shock phenomena were investigated: di raction, re ection and propagation in converging diverging nozzles. Shock{tube experiments were run for shocks with a radius of 165 mm and strength between Mach numbers 1.2 and 1.7. Complementing these were Computational Fluid Dynamics (CFD) and Geometric Shock Dynamics (GSD) simulations where GSD relies on Whitham's equations. On shock di raction, cylindrical shocks were shown to behave qualitatively like plane shocks. Upon encountering a sharp corner, expansion waves propagate along the shock. However, after re ecting o the opposite wall they become compression waves and form a 'Mach re ection (MR)' like con guration on the shock front. A method for calculating the locus of the expansion waves based on Whitham's theory is presented, which on comparison with CFD simulations gives good correlation. Comparisons of shock pro les calculated using Whitham's theory and CFD is also made; it showed good correspondence before the formation of MR like con gurations after which the pro les di er. The re ection of cylindrical shocks was investigated from both an experimental and numerical perspective. Shock{tube experiments were run for shocks propagating on concave cylindrical walls with radii of 100 mm, 180 mm, 140 mm and 82 mm, the range was expanded by use of CFD. An expression for calculating the locus of the MR that forms on iii the shock front was derived which generalises onto plane shocks. Two limits were recognised, one where shock radius is much greater than wall radius and another where shock radius is much smaller. The former corresponds to a cylindrical shock on a plane wall while the latter a plane shock on a cylindrical wall as illustrated by the data gathered. Cylindrical shock propagation in converging-diverging nozzles was also investigated. In this case, the phenomena at play are di raction, re ection and focusing, a combination which results in a complex evolution of the shock front. Two types of channels were investigated, one formed from a 3rd order polynomial and another from circular arcs. In both cases, wall signal were generated on either side of the shock which split the shock{front into three sections. The decreasing channel cross{section area causes the shock strength to increase resulting in very weak MR formation on the shock front. Channels from circular walls exhibit a single peak in the centre line shock strength while that from polynomial pro le walls results in a double peak. This was then related to type of wall disturbance generated. / MT 2017

Bibliography: p. 137-154. / 154 p. : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis details a series of studies in patients, in human volunteers and in large animals. Haemodynamics and left ventricular systolic and diastolic mechanics are reported during lactic acidosis, during therapies for lactic acidosis, and during hyperdynamic and hypovolemic shock. The study has the unifying hypothesis that cardiac dysfunction is important in hyperdynamic and hypovolemic shock and is not caused by lactic acidosis. / Thesis (M.D.)--University of Adelaide, Dept. of Anaesthesia and Intensive Care, 1997?

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