Pyrite (FeS₂) is the major source of sulfur in various coals, and its efficient removal has proven to be a more difficult task than expected. Flotation is generally considered to be the most practicable process for the preparation of coal fines. However, even this technique is usually unable to remove more than 50% of pyrite from a 65-mesh coal sample, which is the typical feed to flotation. There are three major reasons for the low separation efficiency of liberated pyrite from coal by flotation. They include self-induced hydrophobicity of pyrite caused by superficial oxidation, nonselective hydraulic entrainment of pyrite particles into froth product, and incomplete liberation of pyrite from coal that results in composite coal-pyrite particles, i.e., middlings. The present study was undertaken to address problems associated with these recovery mechanisms of pyrite and develop techniques to enhance pyrite rejection in coal flotation. To better understand self-induced hydrophobicity of pyrite, chronoamperometry and voltammetry on freshly fractured electrodes were used to explore incipient oxidation and reduction of the mineral. Voltammetry on rotating ring-disc electrodes (RRDE) was carried out to provide information on soluble species and kinetics of oxidation and reduction processes. X-ray photoelectron spectroscopy (XPS) was used for chemical identification of oxidation products. Galvanic coupling with sacrificial anodes was investigated as a practical method to cathodically protect pyrite and prevent its oxidation. Microflotation tests were conducted under controlled potentials at different solution pH's, and the results were correlated with electrochemical studies. The feasibility of improving pyrite rejection by controlling its surface chemistry was tested in flotation experiments conducted with a 2"-diameter microbubble flotation column and a conventional 5-liter Denver flotation cell. Effects of froth stability on the microbubble flotation of coal were studied with an objective of minimizing hydraulic entrainment of pyrite. The operating parameters were systematically varied to study their effects on water recovery which was used as a measure of froth stability. It has been demonstrated that the upgrading of coal in a flotation column can be significantly improved when froth stability is properly controlled. In an attempt to enhance the rejection of pyrite in middlings, various column circuits were experimentally examined and theoretically analyzed. The effect of circuit configuration on the overall circuit performance was evaluated by separation efficiency and separation curves. It has been shown that the overall separation efficiency of column flotation is rather insensitive to circuitry due to the unique characteristics of the unit flotation column, i.e., the addition of the wash water into the froth. / Ph. D.

The purpose of this study was to determine the mathematics levels commonly used in the performance of four selected occupations. This was compared to the mathematics levels generally required during the education and training for these selected occupations. The four occupations selected for this inquiry were: (1) family practice physician (2) finance officer (3) electronics technician and (4) machinist. A survey instrument was created to ascertain formal mathematical preparation of those working in the selected occupations along with the frequency, importance and use of 60 progressive math topics from the secondary and postsecondary curriculum. A purposive sample of approximately sixty individuals from each of the four occupations participated by completing the questionnaire. Demographic information was collected from each of the participants in order to construct a descriptive profile. Along with the survey, two members of each occupation were interviewed to gain additional insight for the study. A consistent use of basic math, such as adding, subtracting, multiplying, and dividing was being used in all four occupations. Both family practice physicians and finance officers reported using basic math as their primary application level of math on the job. The results of this investigation suggests that the two professional occupations, family practice physician and finance officer, did not use in their jobs the higher math levels they were required to study during their education and training. Conversely, the two technical occupations, electronics technician and machinist, did apply the higher level of mathematics they previously studied in the performance of their duties. Interviews with two members of each occupation supported these findings. Our present educational system is not meeting the needs of a majority of the students it serves. As a result students are leaving school not prepared for future jobs; employers tell us many are not even prepared for today's jobs. This study examined the connection of the educational mathematics requirements of four selected occupations and the mathematics used to practice these occupations. The results of this study provide relevant information that can be used by educational institutions in the preparation of individuals for careers. / Ph. D.

This study sought to determine if there were statistically significant differences between years of teaching experience and education relative to learning-inhibiting problems in the classroom. These differences were measured by responses on surveys, classroom observations, review of summative teacher appraisal instruments and focus group interviews. A population of 271 middle school teachers of language art, social studies, mathematics and science were selected from one urban school district. Analysis of variance (ANOVA) was the statistical analysis procedure utilized to analyze the data. Thirteen null hypotheses were tested at the .05 alpha level. The research failed to reject 12 null hypotheses of no statistically significant difference between years of teaching experience (0-5, 6-12, 13-20, 21+) and education (middle school trained, middle school untrained) and learning-inhibiting problems (chronic talking, refusing request, tardiness, inattentiveness, talking back to teachers) experienced by middle school teachers in the classroom. The only null hypothesis rejected was that no statistically significant difference existed between 0-5 years of teaching experience and the non-instructional strategy (consultation with an administrator) used to prevent learning-inhibiting problems in the classroom. The results of the data analysis revealed that teachers in the 0-5 range of teaching experience preferred consultation with administrators as the strategy for preventing disruptive behavior in the classroom. Upon classroom observation, there was no statistically significant difference between years of teaching experience and the ability to manage a classroom. It was observed that teachers who circulated throughout the classroom while directing instruction and using questioning techniques were better able to manage the classroom and have fewer disruptions than teachers who stood in front of the class or who were seated and directed instruction. Focus group members indicated that many disruptive behaviors can be addressed through appropriate instructional planning and delivery. Therefore, staff development should address a variety of instructional strategies that would prevent and eliminate specific learning-inhibiting problems as chronic talking, tardiness, inattentiveness, refusing request of teachers, and talking back to teachers in the classroom. / Ed. D.

After a review of K12-University partnership models, research into the current local and national education reform context, and an in-depth analysis of contextual factors in the launching of an initiative, the author proposed a program design for K12-University partnerships that included five essential components necessary for successful implementation. These components, also termed leverage points, were: clarity of the problem, outcome planning, a theory of change, clear stakeholder enrollment and commitment, and flexibility. Actively acknowledging and factoring in the fluid nature of public education initiatives, the author framed this program design within that of the emergence principle of complexity theory, which drove the rationale for flexibility in the model. The study then turned to a deep review of the successes and lessons learned from a K12/University partnership that was launched without the benefit of this program design. Finally, the study analyzed this specific K12/University partnership through the lens of the five essential components and made recommendations about the efficacy of this specific model. In the current national climate of declining resources and the need for more effective and innovative partnerships in the K12 and University settings, this program design offered a roadmap for local partnerships throughout the country to positively impact the student success.

During the last two centuries, the development of the internal combustion engine has followed the evolution of the customer expectations. From the race for pure performances, high power, and fun to drive, perfectly well illustrated by the fabulous Mercedes 300 SL, the focus moved towards fuel efficient engines under the pressure of the still increasing oil prices. The well-known Diesel powertrain, up to this period limited to industrial vehicles, suddenly became the object of many researches, even for automotive manufacturers, specialists for sport cars. Technologic developments, mainly concerning turbocharging and injection, allowed the opening of the passenger cars market to CI engines due to acceptable noise, power and still unreachable efficiency. On the gasoline side, direct injection moved from racing to economic cars by the introduction of the stratified combustion. More recently, the pressure rose for dramatically reducing the air pollution, both in urban areas, by limiting NOx and soot, but also, at the scale of the earth, for managing CO2 rejections and thereby enlarging the efforts on efficiency. The two first combustion systems described in this document are concerning spray guided and air guided design alternatives to obtain a fuel stratification, and thereby operate the gasoline engine without throttling the air intake, aiming at a better fuel efficiency. The first concept, called MID3S, was based on a 3 valve combustion chamber with a large squish area and a high compression ratio over 12; inspired from the May Fireball system, it was developed with a house made high pressure injector operating up to 80 bars with an outwardly opening needle. An ultra-lean flame-able mixture was formed at WOT in the vicinity of the spark plug for different operating points as low as idle, while the maximum performances were quite close to the targeted 37 kW/l. The efficiency was significantly improved compared to a similar MPI engine while CO and HC were quite acceptable. On the contrary, NOx and soot would have to be improved. The robustness of the squish aerodynamic motion was unfortunately balanced by the sensitivity of spray angle and penetration versus the back pressure and thereby late injection timings, creating plug wetting and fouling. The hollow cone structure of the fuel plume was clearly responsible of this behavior, especially because of the effect of the air entrainment inside the spray. An increase of the injection pressure from 30 to 80 bar, and probably upper, would probably reduce this effect. Concerning methodologies, a dedicated cylinder head was designed with two endoscope locations in order to visualize the interaction between spray, air, walls and combustion –or more precisely soot- with a high speed camera operating within visible wavelengths. The spray structure, formed by a succession of ligaments at the surface of the plume, was clearly emphasized in atmospheric conditions. The second design, called K5M, was based on an adjustable high tumble motion generated in the intake port. A swirl injector provided by Siemens and located between the two intake valves of the pent roof chamber, was operated until 80 bar. Mixture preparation was relying on the interaction between the air motion and the spray, the tumble velocity deviating fuel droplets towards the spark plug situated at the center of the chamber. 3D CFD simulation, PIV and LIF visualization techniques on an optical single cylinder engine were used in parallel in order to understand the spatial evolution of the equivalence ratio during the cycle and the ability to operate the engine at WOT, even at part load. At low BMEP and speed, the natural reduction of the tumble intensity might have been followed by a significant reduction of the injection pressure in order to secure an accurate balance between the two momentum energies; unfortunately, both high cycle to cycle aerodynamic fluctuations and a poor spray atomization at 30 bar didn’t allow to achieve an acceptable ignition stability at low loads due to a too lean mixture in the plug vicinity. Protruded electrodes could have been a solution to the problem but their reliable use in serial life was not secured. On the contrary, mid load performances were globally adequate. The third concept is concerning Diesel combustion aiming at very low NOx and soot emissions by using an innovative injection system. The basic idea relies on the use of a quite homogeneous combustion at low load –called Mild HCCI- and on a diffusion controlled one at higher loads. Based on two injections close one of the other in the vicinity of TDC, the Mild HCCI allows to moderate the combustion noise inherent to the premixed burning phase as the fuel injected during the second injection cools down the first combustion; the advantages of very low NOx and soot emissions until around 8 bar BMEP are meanwhile maintained. Above this value, the noise level becomes unacceptable for automotive applications and the come back to a conventional diffusive combustion becomes mandatory. Based on early academic investigations pointing out the positive effect of small nozzle holes associated to high injection pressures in terms of soot via a significant difference between the lift-off length and the liquid penetration length, an innovative injection system was adapted to a conventional combustion chamber. The first conclusion was concerning a significant improvement of the NOx/soot tradeoff at mid and high loads with quite usual EGR rates. This advantage was due to a much better fuel atomization linked to both small holes and high pressures. The second conclusion was related to the possibility to achieve a “0 soot/ 0 NOx” combustion at high loads while very much increasing EGR and air mass flows. In this case, a Lifted Flame Diffusion Controlled combustion was generated, confirming on a scale 1 engine the results obtained in academic conditions. Nevertheless, the use of 3D simulation allowed to demonstrate that mixture preparation was only one part of the result; the location of the different stages of the combustion in a Kamimoto diagram, much away from the NOx and soot peninsula, highlighted the impact of the LTC (Low Temperature Combustion) thermodynamics. Unfortunately, despite these good results, industrially available EGR and air systems are not able to provide the necessary mass flows. Concerning tools, the development steps were followed by intensive spray visualizations for both the liquid and the vapor phases, in conditions closer and closer to the actual engine. These measurements allowed to precisely evaluate the impact of the diameter size, the rail pressure and the oxygen content on the difference between lift-off and liquid lengths. Finally, the importance of coupling investigation tools like visualization and 3D simulation in conditions as close as possible to the actual engine in terms of temperature, pressure and timing –eg the ability to record a complete mixture and combustion cycle- has been emphasized for both future SI and Diesel engines. In particular, the forecasted increase of the rail pressures will lead to re-optimize the different available spray models and eventually to re-adapt them in terms of physical phenomena because of the great variations of the spray velocity and of the Weber number. The presence of cavitation in the nozzle holes will also have to be taken into account as it has a key role versus coking. In conclusion, it is quite clear that the development of stratified gasoline and low emissions Diesel engines will more and more rely on the mixture preparation and on its association with low gas temperatures. / Gastaldi, P. (2015). INFLUENCE OF THE MIXTURE PREPARATION ON THE COMBUSTION IN DIRECT INJECTION ENGINES [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/48534

Pretreatment of Pittsburg seam B coals to decrease its ash content and increase its solvent extractable material was investigated by anodically electrolysing acidified coal-water slurries at potentials around 1.0V SCE. The effects of the pretreatment were examined as functions of coal particle size, acid strength of the slurry, time of electrolysis and applied potential. The coal electrolysis was found to be most efficient at low acid strengths and short electrolysis times. The morphology of the coal surface changed with the conditions of the electrolysis and related to the percentage ash removal and the amount of solvent extractable material present in the coal. The anodic oxidation of the coal is suspected to occur via an electrocatalytic(EC) mechanism, whereby ferrous ions in the coal are first oxidised at the anode to the ferric state. The ferric ions migrate into the coal and accept electrons from accessible bonds in the coal micelle thereby reducing themselves back to ferrous ions and return to the anode for re-oxidation to the ferric state. The acceptance of electrons from certain bonds in the coal micelle results in the break-up of the micelle in to simpler compounds. Accordingly, the solubility of the coal in an organic solvent should increase and this was found to be so when ferrous ions were externally added to the electrolyte. The electrolytic process was also found to transfer metallic ions present in the coal into solution in the electrolyte. / Master of Science

Co-crystals are emerging as a potential area in the field of crystal designing as it improves material's physicochemical properties. Many groups are working on the development of newer techniques for the preparation of co-crystals, which can be scalable and contribute to the green agenda. Being continuous and scalable technique, our own developed twin screw extrusion mediated solvent free continuous co-crystallisation (SFCC) technique has been used for the preparation of carbamazepine: saccharin co-crystal. Carbamazepine has been used as a model drug since it shows challenges such as low solubility (BCS class II), polymorphism and thermolabile nature whilst, saccharin was used as a co-former. Effect of extrusion processing parameters such as shear, temperature and screw speed on cocrystallisation has been studied. In addition to this, effect of particle size of co-crystal components, use of hydrated form of carbamazepine, addition of solvent and application of reverse elements on the purity of co-crystal was understood. Use of carbamazepine dihydrate as a starting component yields pure co-crystals. The addition of small amount of polar solvent in anhydrous carbamazepine also yields pure co-crystals whereas particle size did not show any significant effect. Result showed that selection of processing temperature near to eutectic, moderate shear and increase in residence time of component mixture in mixing zone was mainly responsible for co-crystallisation. The extrudates were mainly characterised by XRPD, DSC and in-vitro dissolution tests. Pure co-crystals prepared by addition of highly Development of a solvent free continuous co-crystallisation technique for carbamazepine-saccharin ii polar solvent have been showed drug release identical to that of pure co-crystals prepared by solvent crystallisation.

The objective of this study was to evaluate various multi-stage circuit arrangements that may be used to improve the column flotation of micronized coal. Laboratory flotation tests were performed with two different samples of Pittsburgh No. 8 seam coal. The first coal, Coal A, was ground to two different particle sizes and subjected to both column and conventional flotation. These tests were performed to obtain an initial understanding of the operational behavior of the column process and to compare the results with those of conventional flotation. The second coal, Coal B, was used in the actual testing of three different column circuit arrangements. The experimental test results were compared to simulated results obtained using a rate-based flotation model constructed in the present work. Several hypothetical flotation circuits were also examined using the simulation model and experimental flotation rate data. The circuit test results showed that each of the different circuit configurations possessed specific advantages in terms of throughput capacity, combustible recovery, ash rejection and sulfur rejection. However, the overall performance curves for each circuit were all found to fall on or just below the maximum separation curve predicted using the release analysis technique. Also, the simulated results in almost all cases predicted better results than what was actually obtained. This discrepancy was attributed to the inability of the rate-based model to adequately describe restrictions associated with the carrying capacity of the column froth. / Master of Science

In order to demonstrate the ability of microbubble flotation to superclean coal to ash levels of less than 2%, several Eastern U. S. coals have been tested. The results show that the process is capable of producing superclean coal with improved recovery as compared to the conventional flotation process.To further improve and understand the microbubble flotation process, electrokinetic studies of the hydrocarbon oils used in flotation as collectors have been conducted. Also, the effect of oil emulsifiers on the zeta potential of oil droplets has been studied. In general, oil droplets are negatively charged and negative zeta potential is reduced with the addition of nonionic and cationic surfactants. On the other hand, the negative charge is increased with the addition of an anionic reagent. It has also been shown that the negative zeta potential of oil droplets increases with increasing hydrocarbon chain length.The effects of different collectors on induction time and flotation have been determined by conducting microflotation and induction time experiments using an Elkhorn seam coal sample. The results show that industrial oils combined with the coal have the shortest induction times and, therefore, the highest flotation yields as compared to pure hydrocarbon oils. It has also been shown that oil emulsifiers tend to increase flotation yield and reduce particle/bubble induction time. / Master of Science

The Chemical and Electrochemical Coal Cleaning (CECC) process, designed to remove mineral matter from coal, has been investigated by treating coal samples in acidified slurries. Various coals, characterized by different maceral structures and mineral matter contents, were subjected to several experimental procedures under mild conditions. Substantial amounts of mineral matter (up to 70%) could be extracted from coals which were resistant to physical cleaning, while 22% of sulfur could be removed from pyritic coals. The operating conditions of the CECC were studied in order to determine their influence on the process efficiency. Analyses conducted on solids and leachates resulting from the tests demonstrated that different mechanisms were achieving demineralization by the CECC. Between 50% and 95% of the feed mineral matter was removed by dissolution, whereas the balance could be ascribed to liberation. The CECC process is suitable for cleaning middlings, as well as for further extracting mineral matter from physically clean coals, especially from pyritic vitrinite and fusinite type coals. / Master of Science