Master of Agribusiness / Department of Agricultural Economics / Andrew P. Barkley / The objectives of this thesis is to use regression models and market trends to determine whether the changing product mix of Ardent Mills has an impact on volume, sales dollars, and margin dollars. The results will be used to build a market analysis of Ardent Mills’ product mix strategy. Flour milling is a highly competitive industry. Ardent Mills is constantly looking to increase profits and become more valuable to its customers. Specialty products have created a new opportunity, but the opportunity costs must also be considered. Determining what new products to develop, where to manufacture them, and whether to create new capacity or convert existing capacity are difficult decisions that must be made. The data used in this thesis were collected from Ardent Mills’ sales records from June 1, 2014 through December 31, 2016. Type of product, sales volume, sales dollars, and margin dollars were collected for each month to be analyzed. The study determined that increasing the volume of whole wheat flour sales decreases white flour volume, total flour volume, white flour sales dollars, and total flour sales dollars. Increasing the volume of UltraGrain increases white flour sales dollars and total flour sales dollars. Increasing the volume of wheat-based specialty products increases the volume of white flour and the volume of total flour. As the demand for UltraGrain and wheat-based specialty products increases, the demand for white flour increases as well. Decreasing wheat prices have allowed for additional margin to be captured.

Title of thesis: Polymeric stabilizers maintaining the saturation solubility of itraconazole nanocrystals after dissolution process Author: Jana Kubačková Department: Pharmaceutical Technology Supervisor: PharmDr. Ondřej Holas, Ph.D. Specialized supervisor: Assoc. Prof. Leena Peltonen, Ph.D. The increase of bioavailability of poorly water soluble drugs is still an issue. One of the techniques improving aqueous drug substance solubility, and consequently enhancing bioavailability, is formation of nanoparticles. However, the bioavailability is determined by the concentration of the dissolved drug achieved at the time of absorption. This fact emphasizes the importance of the maintenance of the high solubility until the absorption area is reached. Sufficiently stabilised nanocrystalline drugs offer a solution to this problem. In this thesis, the solid nanoparticle formations of an antifungal agent itraconazole (ITZ) are presented. Wet milling was employed to create the nanosuspension stabilised by binary mixture of stabilisers or by a single stabiliser. An aggregation inhibitor Poloxamer 407 (F127) in the combination with a polymeric precipitation inhibitor hydroxypropyl methylcellulose (HPMC) or polyvinyl pyrrolidone (PVP) at different ratios, or a single precipitation inhibitor, were utilised. The...

Master of Science / Food Science / Fadi Aramouni / Nutrition from whole grains has become an integral part of a healthy diet. Consumers are focused on adding fiber and whole grains to be healthy and want the benefits of whole grain with the taste and appearance of refined flour. A review of current commercial whole wheat flour in the marketplace indicated many options for food processors to use. However, many of these options required processing changes and added ingredients to provide the consumer with a quality product. A milling and baking study was done to compare commercially and experimentally milled whole wheat flours from both white and red wheat varieties. Both white and red wheat varieties were kept identity preserved. Experimental milling was done with a hammer mill and a roll stand to closely replicate the commercial milling process. Baking was done using a sponge and dough method to closely replicate commercial baking conditions. The results showed both particle size and wheat variety impact bake performance of whole wheat flour. The most significant impact appeared to be dependent on the variety of wheat being milled. The milling process also had an impact. As particle size decreased, bake functionality improved. However, some decreased functionality was seen when particle size became very fine. It was concluded that additional work on a commercial flour mill needed to be done to determine if an optimal particle size for milling whole wheat flour exists. Experimental milling equipment was not adequate enough to replicate particle size distributions of commercial whole wheat mills.

Master of Agribusiness / Department of Agricultural Economics / Allen M. Featherstone / The oat processing industry is a competitive industry and maintaining a cost advantage is important for the industry supply chain. General Mills continuously looks to maintain a competitive advantage in the oat supply chain because it is important for strategic short and long term planning. The purpose of this thesis is to analyze supply chain scenarios to determine where future investments should be made. The analysis looks at an existing location, a refurbished location and a Greenfield site. The analysis projects income statements and net cash flows to determine the conclusions using Net Present Value. The question answered is "Should the company continue to invest in the existing supply chain or should it look to different alternatives in the form of a refurbished or Greenfield plant site for production of oat flour?" The analysis found important relationships between the variables that can influence net cash flow and ultimately NPV. However, given the information from this analysis, a determination was made that the existing facility is still the best investment. Future analysis should be used and the company should plan to analyze this issue again in a five to ten year time frame to maintain its competitive advantage.

M.Ing. / The dissertation is an investigation on the implementation of new technologies (five off) in a coal pulverising with main aim to optimise mill maintenance interventions. The technologies in question are: • Stationary air throat replaced with a rotating throat assembly. • Hydro-pneumatic mill loading cylinders replaced with airbags. • Classifier cone modification. • Introduction of triton material for the mill spider guide plates. • High chrome mill grinding balls. Every maintenance intervention, even if planned, negatively affects a plant’s availability and reliability. A Babcock and Wilcox (B&W) at Kriel power station (ESKOM) was used for the testing of the mentioned technologies. The mill model/size is a B&W 10.8E mill. The aim of the introduction of new technology on a mill is to optimise the period between required maintenance activities. A higher availability will assist in achieving good plant maintenance performance indicators. It needs to be noted that the dissertation focussed on the financial and technical parameters of a specific modification. This in an effort to increase uptime and reduce costs as part of a business drive for bigger profit margins. The new technologies tested were thus evaluated from a technical and financial point of view. Each technology was implemented at different time periods and nowhere was any tests performed in parallel on a single mill. To get approval from an investment committee for release of money for tests/modifications, technical and financial assumptions need to be made regarding the performance parameters of the modification/change. Once a modification is being tested, actual plant data can be used as inputs into the execution phase of the modification as assumptions can be replaced with test data. A financial model was developed to “test” the financial feasibility of the proposed changes/modifications. With new technology successful implemented in the plant the current maintenance strategies for maintenance interventions can be re-evaluated as the proposed modifications removed historic barriers that determined the current used based maintenance intervals. An example is where a mill is taken from service to replace or repair the stationary air throat (typically every 5 000 operating hours). With the newly applied technology (rotating throat assemblies), there is no need for maintenance interventions every 5 000hrs as a rotating throat assembly can run without major interventions for 60 000hrs.

Philosophiae Doctor - PhD / Magnesium hydride has long been regarded as a promising candidate for lightweight hydrogen storage applications, owing to reasonably high theoretical capacity (7.6 wt. %). It is burdened by slow absorption/desorption kinetics which has been the target for improvement of many research groups over the years. Nanostructured MgH2 prepared by high energy reactive ball milling (HRBM) of Mg under hydrogen atmosphere with the addition of V or Ti results in modified MgH2 that demonstrates superior hydrogenation/dehydrogenation kinetics without a crippling compromise in storage capacity. Mg – FeV nanocomposites prepared via ball milling of Mg and FeV raw materials demonstrated up to 96.4% of the theoretical storage capacity and comparable kinetics to Mg - V prepared via the same method using pure refined V (which is far costlier than FeV). In both cases, the hydrogenation/dehydrogenation kinetics was much improved than pure Mg alone, as evidenced by faster hydrogenation times. In terms of cyclic stability, Mg – 10FeV demonstrated improvement over pure Mg with final absorption and desorption capacities of 4.93 ± 0.02 wt. % and 4.82 ± 0.02 wt. % respectively over 30 cycles. When compared against Mg – V, Mg – FeV showed slightly inferior improvements, attributed to incomplete hydrogenation of V in the presence of Fe. However, they share similar crystalline BCC, BCT – V2H and FCC - VH phases with the size of less than 10 nm and demonstrated the same behaviour at high temperatures; at temperatures approaching 400 °C, particle sintering became an issue for both nanocomposites resulting in a drop in absorption capacity even in the first cycle. The further inclusion of carbonaceous species showed several effects, one of which was an improvement in hydrogen uptake speed as well as kinetics for the addition of 5 wt. % activated carbon. For the sample with 5 wt. % graphite, the appearance of an initial incubation period of up to 60 minutes was noted, presumably corresponding to the duration of time when the carbon was sheared and crushed before hydrogenation commences.

The aim of the work was to verify the performance and design working quality performance of rotary milling machines with horizontal axis of rotation in artificial forest regeneration, support of natural forest regeneration in selected forest stands and in agriculture with different soil and terrain conditions. The measurement was carried out on four different carrier cutters, each machine carrying a different soil milling machine. Measurements took place in various environments as well as soil types, crops or quality requirements for the work performed. In this work are compared performance of given carriers, in terms of aggregation with individual models of milling machines. The tables show the most important parameters such as average fuel consumption, average area efficiency and fuel consumption to area efficiency. Furthermore, there is an evaluation of the quality of the work done.

The transformations occurring in the sub-stoichiometric Ti(C,N) – W - Al system processed by high energy ball mill were investigated. The milling parameters included the milling time and the temperature comprising milling at subzero temperature and above 25°C. Two sub-stoichiometric Ti(C,N) stocks were selected, the Ti(C0.5N0.05) containing more interstitial elements than the Ti(C0.5N0.5)0.6.The transformation stages and mechanisms of alloying are discussed with respect to the changes in crystal structures of the powder constituents. The milling atmosphere had an effect on the lattice strain of milled products, and hence on the kinetics of solid state dissolution between the powder constituents, but it did not affect the fracturing process. The release of the stored crystallite lattice strain energy was the major determinant in mechanical alloying, with particle size reduction playing a necessary, but less significant role. The strain energy and the fine particle size contributed to the increased chemical reactivity with oxygen of the powders milled for shorter times. The affinity of the powders with oxygen decreased after W dissolution in Ti(C,N), and the subsequent decrease in lattice strains. The annealing behaviour of Ti(C0.5N0.05) - 40wt% W and Ti(C0.5N0.5)0.6 - 40wt% W mechanically alloyed powders were investigated using XRD, TEM, SEM and DTA techniques. It was observed that the reaction start and finish temperatures between constituents were lower in the system that had higher residual lattice strains after milling. The compositions of the intermetallic compounds and the solid solutions formed were dependent on the milling conditions and the annealing temperature. Thermal alloying was observed during annealing of Ti(C0.5N0.05) - 40wt% W mechanically alloyed products, whereas de-mixing of W-rich phases from the metastable solid solution occurred during annealing of the Ti(C0.5N0.5)0.6 - 40wt% W milled powders. The effects of Al addition and milling at subzero temperatures on the transformation of Ti(C0.5N0.05)-W powder mixtures were investigated. Addition of Al powder improved the kinetics of solid solution between powder constituents. The effect of Al was ascribed to the increase of lattice strain during short milling time followed of relaxation at longer time, and to the fast diffusion of atoms. Also, it was noticed that the high viscosity of the process control agent could inhibit the alloying process. Multiple three-component compounds could be formed. Aluminium preferably reacted with tungsten. The W(Al,C) and W(Al,Ti) formed were stable, thus solubility of W in Ti(C0.5N0.05) in the presence of Al was limited. The evolution of the morphologies of Ti(C,N)-W mixtures show that fracturing of hard particles dominated in the early stage of milling in the absence of Al, whereas with Al, plastic deformation of particles and cold welding of Ti(C,N) and W particles by the softer Al prevailed at the same time. Longer milling time improved the homogeneity and the formation of nanostructured binder pools in the sintered products. Lower oxygen contents in sintered PcBN were achieved by mechanically alloying Ti(C,N), W and Al in the high energy ball milling stage. Low level of Co in the infiltration layer was also achieved when sintering PcBN with this type of binder. A link was established between the addition of Al at the attrition milling stage and high oxygen content in the sintered PcBN, thus should be avoided. The pressure and temperature applied during sintering or annealing had a strong effect on the compositions and the crystal structures of the phases formed in the mechanically alloyed binder. The lattice strains of the binder and the PcBN were higher in the sintered materials prepared with the Ti(C0.5N0.5)0.6-W binder than in those made using the Ti(C0.5N0.05)-W alloys.

The demand for materials with high mechanical performances such as Carbon Fiber Reinforced Plastics (CFRP) is increasing. However, there are major challenges in machining CFRP as it involves delamination, fiber pullouts, and extreme cutting tool wear. Analysis of chip formation mechanisms and prediction of associated cutting forces in CFRP machining enables one to address these challenges. This study proposes a mechanistic cutting force model for milling operations of the CFRP workpiece, considering its non-homogeneity and anisotropy, by taking into account variations of fiber cutting angle during machining. A mechanistic model of cutting force constants is obtained from a number of experimentally measured unidirectional CFRP milling forces. The obtained mechanistic force model predictions are verified against experimentally measured milling forces with arbitrary tool path indicating the accuracy of the proposed mechanistic model in predicting cutting forces. The proposed mechanistic cutting force model is capable of being integrated into the manufacturing process to allow optimized machining of quality certified CFRP work-pieces. / Graduate

Thesis advisor: Zhifeng Ren / Thermoelectric (TE) technology is an environment-friendly one due to reduction of carbon emission, which can be widely used either for power generation or for refrigeration. Basically applications of TEs are based on TE effects, which involve the transition between heat and electricity. Despite the superior advantages of being solid state and providing a clean form of energy, TE technology so far only finds its niche area of application due to the relatively less efficiency compared to traditional methods. The efficiency of a thermoelectric device is solely determined by the dimensionless figure-of-merit (ZT) of thermoelectric materials. According to the definition, ZT is equal to square of Seebeck coefficient times electrical conductivity times absolute temperature divided by thermal conductivity. Therefore, a good thermoelectric material should possess high Seebeck coefficient and electrical conductivity while low thermal conductivity, so called phonon glass electron crystal (PGEC). In bulk materials, it is challenging to further improve ZT or independently vary individual parameters without affecting others, mainly due to the interrelated relationships among these three parameters. Fortunately, nano approach gives us some independent control in parameters adjustment. One important aspect of nano idea lies in the fact that enhanced boundary scattering due to the increased intensities of interfaces arising from nano-sized grains could reduce the thermal conductivity more than the electrical conductivity, which is practically realized in our material system. Since the introduction of nano idea, large ZT as high as above two has been achieved in the superlattice system. Due to the high fabrication cost of superlattices, they are not scalable for mass production. Theoretical calculations indicate that thermal boundary resistance is the main mechanism for the low thermal conductivity in superlattices, rather than the periodicity. Basically, we hope to achieve the supplattice-like ZT in the less costly bulk nanograined materials, based on the idea that reduction of thermal conductivity which is responsible for ZT enhancement in superlattices can be realized in bulk materials with embedded nanostructures as well. Inspired by the nanocomposite idea, in my thesis work I applied the technique of ball milling and then hot press to various thermoelectric materials, from low temperature to high temperature, demonstrating the feasibility of the approach. By ball milling alloyed ingot into nanopowders and DC hot pressing them, we have achieved a 62-89% ZT improvement for p-type half-Heusler samples, mainly due to the significantly enhanced Seebeck coefficient and partially due to the moderately reduced thermal conductivity. Microstructure studies indicated that increased boundaries due to smaller nano-sized grains is the cause for change of parameters. For our ball milled samples, the trend of decreasing thermal conductivities with increasing ball milling time is observed, further substantiating our nano-approach idea because longer ball milling time gives rise to smaller grain sizes and thus stronger boundary scattering. By applying the same technique to n-type half-Heuslers, we also successfully obtained pronounced enhancement in ZT especially at medium and low temperature ranges, which might be useful in medium temperature power generation. By ball milling a mixture of individual constituent elements into alloyed nanopowders and then DC hot pressing them, we did not gain improvement in ZT initially for n-type BiTeSe system mainly due to the simultaneous reduced power factor with the thermal conductivity. Considering anisotropic properties of the n-type BiTeSe single crystal and randomization effect of ball milling process, we repressed the as-pressed bulk samples in a bigger diameter die, during which lateral flow took place, resulting in preferred grain orientation. As a result, a 22% improvement in the peak ZT from 0.85 to 1.04 at 125 oC in n-type Bi₂Te_2.7Se_0.3 has been successfully achieved, arising from the more enhanced power factor than the thermal conductivity. Compared with single crystal, we benefit from the small nano-sized grains in bulk materials. Taking into account the in-plane power factor of single crystal, we still have much room for further ZT improvement if more ab orientation is promoted into the disk plane and/or the crystal plate size and thickness are reduced. By applying our technique of ball milling and then hot press to p-type skutterudites system, we have achieved a peak ZT of 0.95 at 450 <super>o</super>C in NdFe_3.5Co_0.5Sb₁₂, which is comparable to that of the state-of-the-art ingot. Our approach has the advantage of being less costly and more time-efficient compared to traditional fabrication methods. Besides, even lower thermal conductivity and hence higher ZT can be expected, provided that the nanosize of the precursor powder is preserved during hot press. The nanocomposite idea has been substantiated and the feasibility and generality of our ball milling and then hot press approach has been demonstrated, based on the thermoelectric properties data we obtained and the microstructure studies we carried out from various thermoelectric material systems, from low temperature to high temperature. We believe that continued effort in the area of thermoelectrics by our approach should be paid with superlattice-like ZT if ingenious methods are devised to control the grain growth during consolidation. / Thesis (PhD) — Boston College, 2010. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Physics.