Mathematical and empirical modeling of chemical reactions in a microreactor

This dissertation is concerned with mathematical and empirical modeling to simulate three important chemical reactions (cyclohexene hydrogenation and dehydrogenation, preferential oxidation of carbon monoxide, and the Fischer-Tropsch (F-T) synthesis in a microreaction system. Empirical modeling and optimization techniques based on experimental design (Central Composite Design (CCD)) and response surface methodology were applied to these three chemical reactions. Regression models were built, and the operating conditions (such as temperature, the ratio of the reactants, and total flow rate) which maximize reactant conversion and product selectivity were determined for each reaction. A probability model for predicting the probability that a certain species undergoing reaction inside a microreactor exits the reactor by a certain time T was applied to cyclohexene hydrogenation and dehydrogenation reaction and the F-T synthesis reaction. The probability is estimated by the partial pressure of the reactant in the exit stream divided by the base partial pressure without the reaction (pp/base). Parameters of the residence time distribution and the reaction rate were estimated for these chemical reactions. Lastly, the activation energy of these reactions was estimated, and the flow behavior of the reactant gas inside the microreactor was characterized from the residence time distribution. A stochastic Markov chain approach was used to simulate cyclohexene hydrogenation and dehydrogenation reaction, and preferential oxidation of carbon monoxide reaction in a fuel cell. Simulation results from the stochastic approach were presented. Simulation results were in qualitative agreement with experimental results

The Silver Standard in Prewar China, A Blessing or A Curse?

When the rest of the world sank deeper into the mire of gold shortage and the Great Depression, China, a country still adhered to the silver standard, maintained a relative independent connection to the global economy. In the initial stage of the Great Depression, Chinese economy under relative inflation benefited from the blessing of the silver standard. However, with international silver prices artificially being pushed up especially after the U.S. silver purchase act in 1934, the price of silver surged twice merely in two years. Millions of silver currency was exported from China to invest in financial speculation. Acute silver reserves shortage put a curse on Chinese economy and forced the Nanking government to abandon the silver standard in 1935. Contemporary observers recorded prewar Chinese economy dropping to serious downward spirals while macroeconomic indicators did not show obvious decreases. To figure out whether prewar China suffered from exorbitant silver price, quantitative analysis was carried out based on trusty adjusted trade indexes, separating the cause of aggregate trade fluctuations into price and quantity factors. The general conclusion is that the Chinese economy developed from 1929 to 1931 and then experienced sharp contraction from 1932 to 1935. OLS regression results further verified that widespread speculation had motivated silver flight in prewar China