With size down to nanoscale, nanomaterials exhibit novel properties exceeding or differing significantly from their bulk counterparts. In particular, amongst a wide range of interesting new nanostructures, tungsten based nanomaterials have demonstrated super physical, chemical, electronical and mechanical properties in a diverse range of applications which has been comprehensively reviewed. However, challenges still remain high on the effective processes to scale up the manufacturing of such nanomaterials, with desired shape, size and quality. These tungsten based nanomaterials are thus become the research subject of this project, and the study on continuous manufacturing of specifically inorganic fullerene WS2 (IF-WS2) nanoparticles, and their potential exploration as fillers to polymer matrix to fabricate nanocomposites with improved mechanical properties are the main objectives of this research. After a thorough assessment of the extremely promising potentials of tungsten based nanostructures, and review of the current bottleneck for large quantity production of IF-WS2, a generic experimental methodology and techniques used for the investigations have been described in experimental methodology part. In the following chapters, this thesis demonstrates the following research works: A novel rotary furnace for continuous scaling up manufacturing of IF-WS2 nanoparticles has been designed, constructed, tested and refined in this work. The new furnace consists of several key components: a tube furnace, self-contained rotary system, dynamic seal system, modified new tube with baffle, and a continuous gas-blow feeding system. Test results show that the rotary reactor has improved the lab scale manufacturing of IF-WS2 from sub-gram to several tens of grams per batch without agglomeration, which makes this technique a promising alternative for the replacement of the existing tall fluidised tower processing in industrial level production. As an important precursor for IF-WS2 nanomaterials production, the synthesis of WOx nanoparticles by high temperature thermal decomposition of Ammonium Paratungstate (APT) has been investigated, and the parameters have been optimised (with Ar flow at 6 L/min at 1350°C ) for achieving desired sizes. Further studies on the creation of uniform and ultra-thin WOx nanowires were carried out using solvothermal technique. The solvent concentrations, reaction time and solvent types have been systematically investigated, and the resulting WOx nanowires from tungsten chloride precursor in mixed cyclohexanol and ethanol solvent exhibited a record high specific surface area of 275 m2/g. This is fundamentally significant for their applications in sensor and electro-chromic devices. Reverse patterned growth of WOx nanorods was realised for the first time on an Au-coated W foil by a simple W-water vapour reaction. The resulting nanorods of different diameters, lengths and patterns have been created by tuning the growth parameters. Further nitriding under NH3 atmosphere at elevated temperature, converted the WOx nanorods, as a template, to WOxNy nanorods. The WOxNy nanorods have been found to inherit the patterns on the substrate and kept the size and shape of WOx nanorods. An interesting morphology revolution for the conversion of WOx to WOxNy nanorods was observed, and a mechanism has been proposed accordingly to account for the growth. This result represents a simple, innovative and efficient process for the reverse-patterned growth of new nanomaterials. Further development of the rotary furnace has led to a unique new class of core-shell composite nanoparticles, carbon (C)-coated IF-WS2 hollow nanoparticles, by continuous chemical vapour deposition (CVD) production. The composite nanoparticles exhibited a uniform and adjustable C coating, with little or no agglomeration. Importantly, the thermal stability of the core-shell C-coated IF-WS2 against oxidation in air has been improved by about 70°C, compared to the pristine IF-WS2. This new material could find applications where thermal stability is critical. Exploration of 0-4 wt% IF-WS2 as reinforcement in nylon 12 matrix nanocomposites has been carried out for the first time, using a combination of ultrasonic dispersion and magnetic stirring technique to achieve excellent IF-WS2 dispersion in the matrix. Tensile and bending test results showed moderate improvements of 27% and 28% respectively, with a 2 wt% IF-WS2 addition, but a staggering 185% and 148% improvement in toughness for the addition of 0.25 and 0.5 wt% IF-WS2 samples, against pure nylon 12, suggesting that such composites are promising candidates for structural and ballistic fibre applications.

The purpose of this study was to test the number of rotations to fracture of the M-Wire GT® Series X(TM) rotary files compared to the original ProFile® GT® rotary files in a simulated curved canal. Eighty GT® Series X(TM) files of 25mm length were divided into eight groups of ten, one for each of the new GT® Series X(TM) files. Eighty original ProFile® GT® files of 25mm length were divided into eight groups of the same tip and taper sizes consistent with the GT® Series X(TM) file groups. Files were rotated at 300 rpm. While the angle may have slightly changed due to the flexure property of the file, the angle was the same for each file with the same tip and taper. The time to fracture was recorded and rotations to fracture were calculated. The data collected was analyzed using a two-way ANOVA, followed by specific post-hoc contrasts comparing the two brands for each tip and taper combination. The results show the M-Wire GT® Series X(TM) files were significantly more resistant to fracture by cyclic fatigue than the ProFile® GT® rotary instruments for the following tip and taper sizes: 20/.04, 30/.04, 30/.06, 30/.08, and 40/.08. The following tip and taper sizes: 20/.06, 40/.04, and 40/.06 were not statistically significant.

The purpose of this study was to examine the number of rotations to failure of two different rotary file systems, EndoSquence Brassler USA (Savannah, GA) and GT(TM) series X(TM). Files sizes 20,30,40 with 0.04, 0.06 tapers of GT series X and Endo Sequence files size and taper used were 20, 30, 40 with 0.04 and 0.06 taper. Like tip and tapers were compared between systems. All files tested were 25mm in length. Files were allocated into 12 groups of 10 files each, and mounted to a universal testing machine. Each file was rotated at 300 rpms until fractured occurred. The number of rotations to fracture were calculated. A two-way ANOVA indicated that each of the 12 groups were significantly different (p < .0001). The Brand Tip/Taper interaction indicated that the differences between the brands varied by Tip/Taper combination (p < .0001). The tip/taper combination 20/.04, the GT series X file rotated 1.4 times longer than the EndoSequence (p = 0.0027). The tip/taper combination 20/.06, the GT series X file rotated 1.61 times longer than the EndoSequence (p = <.0001). The tip/taper combination 30/.04, the GT series X file rotated 3.67 times longer, than the EndoSequence (p = <.0001). For the tip/taper combination 30/.06, the GT series X file rotated 2.63 times longer than the EndoSequence (p = <.0001). For the tip/taper combination 40/.06, the GT series X file rotated 4.05 times longer than the EndoSequence (p = <.0001). In comparing all these tip and taper combinations GT series X was significantly higher rotations to failure. Comparing tip/taper combination 40/.04, the GT series X file rotated 1.22 times longer, however, this was not significantly different than the Sequence (p = 0.0707). The results suggested that the number of rotations to failure for GT series X files were greater than the EndoSequence file of the same tip and taper combination.

The purpose of this study was to compare the resistance to fracture by the twisting of two nickel titanium (NiTi) rotary file systems. The Profile® GT® (GT) and the GT® Series X(TM) (GTX) files were tested to analyze the maximum torsional strength and the maximum angular deflection at the time of separation of the files. For each system, ten new files were tested at each of the following eight taper/size designations for a total of 160 files: 20/0.04, 20/0.06, 30/0.04, 30/0.06, 30/0.08, 40/0.04, 40/0.06, and 40/0.08. The American National Standards Institute / American Dental Association Specification No. 28 was implemented to evaluate torsional limits for these intruments. Files were mounted in a Maillefer Torsiometre machine, which records maximum torsional strength and angular deflection at separation for each file. A two-way ANOVA revealed significant differences after comparing the size and type of file. The GT files required significantly more torque to separate than the GTX files in all groups tested except the GTX file size 20/0.06, which required significantly more maximum torque than the GT file, with no significant difference between the GT and GTX files for size 30/0.04. The GT files exhibited values for angular deflection at separation that were significantly higher than those for the GTX files at sizes 30/0.04 and 40/0.08 and the GTX files exhibited higher values at size 30/0.08 with no significant difference between the brands at the remaining five file sizes. In summary, the GT files required significantly more torque to fracture and exhibited values for angular deflection at separation that were significantly higher than the GTX files for in 6 of 8 and 2 of 8 file sizes, respectively.

The aim of this study was to compare the incidence of root canal dentinal micro-cracks after canal instrumentation using reciprocating files (WaveOne Gold® and Twisted Adaptive®) and continuous rotation files (Edge Evolve® and EndoSequence®) in an ex-vivo benchtop study. This project used a novel methodology of finding dentinal defects using the “K-cube”, which allows evaluators to visualize sectioned root surfaces before instrumentation and after instrumentation. Mesial roots from 40 human mandibular first molars were divided into 4 groups of 10 for each file type. Root section pictures were taken with a Zeiss Discovery V20 stereomicroscope before and after canal instrumentation. Each of the pre-instrumentation and post-instrumentation images were evaluated for dentinal defects by four calibrated endodontists utilizing REDCap survey. Using a chi-square analysis, there was no statistically significant difference between dentinal defects created by continuous and reciprocating rotation (p=0.1924) and no difference between the four file types (p=0.2317).

Doctor of Philosophy / Department of Industrial & Manufacturing Systems Engineering / Zhijian Pei / High-performance materials, such as silicon, aerospace stainless steels, titanium alloys, and carbon fiber reinforced plastic (CFRP) composites, have a variety of engineering applications. However, they usually have poor machinability and are classified as hard-to-machine materials. Drilling is one of the important machining processes for these materials. Industries are always under tremendous pressure to meet the ever-increasing demand for lower cost and better quality of the products made from these high-performance materials. Rotary ultrasonic machining (RUM) is a non-traditional machining process that combines the material removal mechanisms of diamond grinding and ultrasonic machining. It is a relatively low-cost, environment-benign process that easily fits in the infrastructure of the traditional machining environment. Other advantages of this process include high hole accuracy, superior surface finish, high material removal rate, low tool pressure, and low tool wear rate. The goal of this research is to provide new knowledge of machining these high performance materials with RUM for further improvement in the machined hole quality and decrease in the machining cost. A thorough research in this dissertation has been conducted by experimental, numerical, and theoretical investigations on output variables, including cutting force, torque, surface roughness, tool wear, cutting temperature, material removal rate, edge chipping (for silicon), power consumption (for CFRP), delamination (for CFRP), and feasible regions (for dry machining of CFRP). In this dissertation, an introduction of workpiece materials and RUM are discussed first. After that, two literature reviews on silicon drilling and dry drilling are presented. Then, design of experiment and finite element analysis on edge chipping in RUM of silicon, experimental investigations and finite element analysis on RUM of aerospace stainless steels, an ultrasonic vibration amplitude measurement method and a cutting temperature measurement method for RUM using titanium alloys as workpiece, experimental and theoretical investigations on RUM of CFRP composites, and experimental studies on CFRP/Ti stacks are presented, respectively. Finally, conclusions and contributions on RUM drilling are discussed.

Calcined coke is the best material for making carbon anodes for smelting of alumina to aluminum. Calcining is an energy intensive industry and a significant amount of heat is wasted in the calcining process. Efficiently managing this energy resource is tied to the profit margin and survivability of a calcining plant. 3-D computational models are developed using FLUENT to simulate the calcining process inside the long slender kiln. Simplified models are employed to simulate the moving petocke bed with a uniform distribution of moisture evaporation, devolatilization, and coke fines entrainment rate with a conjugate radiation-convection-conduction calculation. The results show the 3-D behavior of the flow, the reaction inside the kiln, heat transfer and the effect of the tertiary air on coke bed heat transfer. The ultimate goals are to reduce energy consumption, recover waste-heat, increase thermal efficiency, and increase the product yield.

Biochar has been heralded as a promising technology for climate change mitigation that can also benefit soils. Biochar is a carbonaceous solid produced by pyrolysis of biomass – the thermal decomposition of plant and plant-derived matter in the absence of oxygen. When added to soils, biochar has the potential to increase crop yields and suppress soil emissions of greenhouse gases, whilst sequestering carbon in a stable form. In addition to biochar, biomass pyrolysis produces liquids and gases that can serve as biofuels. Biochar production systems that generate excess heat or power are particularly environmentally and economically attractive. Rotary kilns are the favoured process reactor in many industries, given their potential to handle a wide range of feedstocks and provide good process control. This thesis investigates the potential to coproduce biochar and excess biofuels by slow pyrolysis in a pilot-scale rotary kiln. The work attempts to progress towards the ultimate aim of scaling up the rotary kiln and optimising its operating conditions to produce biochar of good quality along with an excess of useful biofuels. Experimental work, involving the development and application of new methodologies, was used to gain a better understanding of the process. The data gathered were then used to support preliminary numerical simulation efforts towards the development of a comprehensive process model. Five biomass feedstocks were considered: softwood pellets, miscanthus straw pellets, wheat straw pellets, oilseed rape straw pellets and raw rice husks. The granular flow of biomass feedstocks was observed in a short closed drum faced with acrylic and resting on rollers. All pelletized feedstocks displayed similar angles of repose, validating the use of softwood pellets as a model biomass for these feedstocks. Bed mixing, which can improve product uniformity, was slow under typical operating conditions, requiring 5 min to complete at 4 rpm for softwood pellets. Mixing quickened considerably at higher rotation rates. A digital image analysis method was developed to measure the distribution of solid residence times inside the rotary kiln. The mean residence time of softwood pellets ranged from 19 to 37 min under typical operating conditions, decreasing with increases in kiln rotation rate, but mostly unaffected by feeding rates. These findings show that kiln rotation rates must be selected to balance the residence time of solids inside the kiln with bed mixing levels. Thermogravimetry and differential scanning calorimetry were performed on samples of ground softwood pellets under five different heating profiles to study the kinetics and heat flows of the pyrolysis process. Both exothermic and endothermic regions were identified, with most reactions taking place between 250°C and 500°C. Results suggest that exothermic pyrolysis reactions can be promoted by altering the process heating rate, thereby improving net biofuel yield from the process. The thermogravimetric data collected was used to develop a distributed activation energy model (DAEM) of the kinetics of softwood pellet pyrolysis for integration into a comprehensive model of the process. The applicability of the kinetic model to large-scale processes was confirmed using a simplified process model developed to simulate biomass pyrolysis inside the pilot-scale rotary kiln. Although crude, the simplified process model produced sufficiently accurate estimates of char yield for preliminary design purposes. The simplified model also allowed important process parameters, such as kiln filling degree, solid residence time and heating rate, to be evaluated. A series of pyrolysis experiments was performed on the pilot-scale rotary kiln to evaluate the yields of biochar and biofuels and determine the temperature profile inside the kiln. This work required the design of a suspended thermocouple system that measures temperatures along the kiln, both in the gas phase and inside the solid bed. For most experiments at 550°C, a region of high temperature gas and solids was observed, possibly indicative of exothermic reactions. Biochar yield varied from 18% to 73% over the range of feedstocks and operating conditions tested. A vapour sampling methodology that relies on the use of a tracer gas was developed to determine the yield of pyrolysis liquids and gases. Due to analytical difficulties, it was not possible to obtain accurate mass closure with this method. However, the methodology revealed significant air ingress into the pilot-scale rotary kiln that is responsible for partially combusting biofuels produced by the process, thereby reducing their calorific value. Energy balances on the kiln confirmed that the calorific content of pyrolysis liquids and gases exceeds the energetic demand of the process, yielding between 0.3 and 11 MJ in excess biofuels per kg of biomass feedstock. An attempt was made to develop a multiphase model of the flow of vapours and solids inside the rotary kiln using computational fluid dynamics (CFD), but the continuous modelling approach was found inadequate to simulate the dense bed of biomass inside the kiln. The discrete element method (DEM) was sought as an alternative to model the granular flow of biomass inside the kiln. Extensive parameter calibration was required to reproduce the experimental behaviour of softwood pellets observed in the short closed drum. A model of the pilot-scale rotary kiln was constructed to simulate particle residence times. Further parameter calibration was required to replicate softwood pellet holdup inside the kiln. The calibrated model was able to reproduce the mean residence time of softwood pellets within 10% under different kiln operating conditions. However, simulated residence time distributions could not be established as a result of the long execution times required for this modelling work. Few data are currently available on large-scale continuous biomass pyrolysis processes; the experimental data gathered in this thesis help to fill this gap. Along with the numerical simulation work presented herein, they provide the foundation for the development of a comprehensive model of biomass pyrolysis in rotary kilns. Such a numerical model would prove invaluable in scaling up the process and maximizing its efficiency. Future work should consider the agronomic value and carbon sequestration potential of biochar produced under different operating conditions. In addition, the performance and efficiency of different conversion technologies for generating heat and power from biofuels need to be investigated.

abstract: Rotary drums are commonly used for their high heat and mass transfer rates in the manufacture of cement, pharmaceuticals, food, and other particulate products. These processes are difficult to model because the particulate behavior is governed by the process conditions such as particle size, particle size distribution, shape, composition, and operating parameters, such as fill level and rotation rate. More research on heat transfer in rotary drums will increase operating efficiency, leading to significant energy savings on a global scale. This research utilizes infrared imaging to investigate the effects of fill level and rotation rate on the particle bed hydrodynamics and the average wall-particle heat transfer coefficient. 3 mm silica beads and a stainless steel rotary drum with a diameter of 6 in and a length of 3 in were used at fill levels of 10 %, 17.5 %, and 25 %, and rotation rates of 2 rpm, 6 rpm, and 10 rpm. Two full factorial designs of experiments were completed to understand the effects of these factors in the presence of conduction only (Case 1) and conduction with forced convection (Case 2). Particle-particle friction caused the particle bed to stagnate at elevated temperatures in Case 1, while the inlet air velocity in Case 2 dominated the particle friction effects to maintain the flow profile. The maximum heat transfer coefficient was achieved at a high rotation rate and low fill level in Case 1, and at a high rotation rate and high fill level in Case 2. Heat losses from the system were dominated by natural convection between the hot air in the drum and the external surroundings. / Dissertation/Thesis / Masters Thesis Chemical Engineering 2019

The development and induction in-service of Unmanned Air Vehicles (UAV) systems in a variety of civil, paramilitary and military roles have proven valuable on high-risk missions. These UAVs based on fixed wing configuration concept have demonstrated their operational effectiveness in recent operations. New UAVs based on rotary wing configuration concept have received major attention worldwide, with major resources committed for its research and development. In this thesis, the design process of a rotary-wing aircraft was re-visualised from an unmanned perspective to address the requirements of rotary-wing UAVs - Vertical Take-off UAVs (VTUAV). It investigates the conventional helicopter design methodology for application in UAV design. It further develops a modified design process for VTUAV addressing the requirements of unmanned missions by providing remote command-and-control capabilities. The modified design methodology is automated to address the complex design evaluations and optimisation process. An illustration of the automated design process developed for VTUAVs is provided through a series of inputs of the requirements and specifications, resulting in an output of a proposed VTUAV design configuration for