This thesis is focused on monitoring attributes of ettringite in long term horizon, especially on his thermodynamic stability. Ettringit was prepared in two ways. Firstly, it is a method of hydration of yeelimite, secondly, ettringit is prepared by addition of aluminium sulphate and calcium hydroxide.

This diploma thesis is focused on evaluation of the possibilities of using FBC ash for production of blended cement and monitoring the hydration process, specially creation of the AFt phases.

This dissertation includes three topics. First topic: Regularized estimation in the AFT model with high dimensional covariates. Second topic: A novel application of quantile regression for identification of biomarkers exemplified by equine cartilage microarray data. Third topic: Normalization and analysis of cDNA microarray using linear contrasts.

Master of Arts / Department of Statistics / Paul Nelson / There are two important statistical models for multivariate survival analysis, proportional hazards(PH) models and accelerated failure time(AFT) model. PH analysis is most commonly used multivariate approach for analysing survival time data. For example, in clinical investigations where several (known) quantities or covariates, potentially affect patient prognosis, it is often desirable to investigate one factor effect adjust for the impact of others. This report offered a solution to choose appropriate model in testing covariate effects under different situations. In real life, we are very likely to just have limited sample size and censoring rates(people dropping off), which cause difficulty in statistical analysis. In this report, each dataset is randomly repeated 1000 times from three different distributions (Weibull, Lognormal and Loglogistc) with combination of sample sizes and censoring rates. Then both models are evaluated by hypothesis testing of covariate effect using the simulated data using the derived statistics, power, type I error rate and covergence rate for each situation. We would recommend PH method when sample size is small(n<20) and censoring rate is high(p>0.8). In this case, both PH and AFT analyses may not be suitable for hypothesis testing, but PH analysis is more robust and consistent than AFT analysis. And when sample size is 20 or above and censoring rate is 0.8 or below, AFT analysis will have slight higher convergence rate and power than PH, but not much improvement in Type I error rates when sample size is big(n>50) and censoring rate is low(p<0.3). Considering the privilege of not requiring knowledge of distribution for PH analysis, we concluded that PH analysis is robust in hypothesis testing for covariate effects using data generated from an AFT model.

Thesis (M.Ing. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2009.

It has been ingrained into the American consciousness that our public schools are failing and our students are underachieving. This is something we all know. What is less clear is why American schools are failing. Time and time again, we come back to teachers, who have been identified as the single greatest factor in determining the success of the student. Teachers can make the difference in the lives of students and help secure our economic future. Teachers unions speak for these teachers, thus, in our search for a scapegoat, teachers unions often rank at the top. Right or wrong, it is a serious accusation to say that teachers unions are responsible for the failure of the American education system. Teachers, and consequently teachers unions, have the power to greatly impact education reform. After assessing the state of education in the United States and establishing teachers unions’ role in the bigger picture of education, I will first explore the source of teachers unions political power: their large membership and their money. Teachers unions are among the largest unions in the country and the NEA (National Education Association), specifically, is the highest political contributor of all public sector unions. To assess their political influence, I will show where and how they use their money with the intention of evaluating whether or not they overstep their boundaries as a typical labor union. The next important variable to consider when evaluating the impact of teachers unions is their classification as a public sector union. Private and public sector unions operate under different sets of laws and thus have different rules and strategies for collective bargaining. I will examine how their public sector status impacts their influence on hotly contested education reform issues, such as teacher performance pay, teacher evaluations based on student achievement, school vouchers, and charter schools. What makes teachers unions different from other labor unions? And do these differences give teachers unions a detrimental amount of control over education reform?

以往對於消費者對基因改造食品偏好及願付價格估計之研究，如 Moon (2001)、Chern et al. (2002)和Fu (2004)，都是將兩個研究目的 分開個別處理，因此就統計的觀點來說，這樣的分析方式是比較缺乏 效率的。 本研究中提出一個整合式的分析方式，來分析台灣消費者對於基 因改造食品的偏好以及願付溢價。本方法除了增進統計效率外，也同 時納入願付價格分析中可能遇到因為受訪者對該財貨有強烈偏好，對 於該財貨有再高價格都願意支付的傾向，因此預期本方法將可提供更 高的準確度。 為了研究台灣民眾對基因改造鮭魚的認知行為，中央研究院調查 研究專題中心在2003 年進行了全台的電話訪問。而本研究發現台灣消 費者願意多付目前平均市價之12%來購買非基因改造飼料餵食之鮭 魚。此外，消費者本身對於基因改造科技的看法、對基因改造科技的 了解、以及消費者的年齡將扮演影響消費偏好以及願付溢價的高低之 重要因素。 / Previous researchers, such as Moon (2001), Chern et al. (2002), and Fu et al. (2004), attempted to analyze consumer preference toward genetically modi¯ed pro- duces and to estimate a willingness to pay for them. These two objectives, however, have been conducted separately and therefore are de¯cient in statistically e±ciency. An integrated technique is introduced to understand how consumers in Taiwan perceive genetically modi¯ed produce as well as how much they are willing to pay a premium simultaneously. Apart from improving statistical e±ciency, this newly proposed method also considers the possibility that consumers might be willing to any price if he/she strongly prefer this goods. Higher precision is expected under this scenario. To investigate how public perceive genetically modi¯ed salmon, Center for Sur- vey Research, Academia Sinica, conducted a telephone survey to Taiwanese con- sumers in 2003. Our study indicates that consumers are willing to pay a premium, about 12% of the average market price, for non-GM-fed salmon rather than GM-fed counter part. Moreover, the way consumers think of the risk regarding GM food, how much they know about GM food, and their age will all in°uence their consump- tion tendency and willingness to pay.

Coal, as energy resource, possesses numerous characteristics and properties which all have an influence on its gasification behaviour. The two properties considered critically important when evaluating a coal source for gasification are its mineral content and slagging behaviour. Research has indicated that slag formation can be inhibited or even prevented by the addition of a fluxing agent. It is thus of great importance to understand the mineral interaction during gasification, in order to select a suitable fluxing agent for the prevention of slagging and clinker formation in the gasifier. The aim of this dissertation is to evaluate the slagging properties of a coal source with the addition of iron as a fluxing agent and to study the transformation of the mineral and added iron during gasification. A pre-determined amount of elemental iron (between 2 and 20 percentage by mass) was added to three different coal samples obtained from Sasol's operations in South Africa. The transformation of the iron in conjunction with the possible iron-containing minerals present in the coal was studied by means of Mossbauer spectroscopy. Typical characterisation analyses were also carried out on the original coal samples. The ash fusion temperature analyses (AFT) were used to study the slagging behaviour of the iron-spiked coal samples. Even though AFT analyses only provide an average flow property, it gives a good indication of the changes that the iron addition induces in coal properties. FactSage modelling was carried out in conjunction with the Mossbauer and AFT analyses. The AFT analysis on all of the samples indicated that the iron addition led to a 20% decrease in the AFT of all three the coal samples. The decrease observed, can be attributed to three main reasons: Formation of lower melting iron-containing phases, bridging of oxygen bonds by FeO and Fe203and the lowering of the viscosity by the iron-oxides, mainly hematite. Mossbauer spectra of the three original coal samples indicated that pyrite was the only iron-bearing mineral present / Thesis (M.Ing. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2009.

Coal, as energy resource, possesses numerous characteristics and properties which all have an influence on its gasification behaviour. The two properties considered critically important when evaluating a coal source for gasification are its mineral content and slagging behaviour. Research has indicated that slag formation can be inhibited or even prevented by the addition of a fluxing agent. It is thus of great importance to understand the mineral interaction during gasification, in order to select a suitable fluxing agent for the prevention of slagging and clinker formation in the gasifier. The aim of this dissertation is to evaluate the slagging properties of a coal source with the addition of iron as a fluxing agent and to study the transformation of the mineral and added iron during gasification. A pre-determined amount of elemental iron (between 2 and 20 percentage by mass) was added to three different coal samples obtained from Sasol's operations in South Africa. The transformation of the iron in conjunction with the possible iron-containing minerals present in the coal was studied by means of Mossbauer spectroscopy. Typical characterisation analyses were also carried out on the original coal samples. The ash fusion temperature analyses (AFT) were used to study the slagging behaviour of the iron-spiked coal samples. Even though AFT analyses only provide an average flow property, it gives a good indication of the changes that the iron addition induces in coal properties. FactSage modelling was carried out in conjunction with the Mossbauer and AFT analyses. The AFT analysis on all of the samples indicated that the iron addition led to a 20% decrease in the AFT of all three the coal samples. The decrease observed, can be attributed to three main reasons: Formation of lower melting iron-containing phases, bridging of oxygen bonds by FeO and Fe203and the lowering of the viscosity by the iron-oxides, mainly hematite. Mossbauer spectra of the three original coal samples indicated that pyrite was the only iron-bearing mineral present / Thesis (M.Ing. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2009.

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