Mechanical Engineering Students Project-Based Learning in OUAS

This chapter introduces project-based learning approach which is used in the Oulu University of Applied Sciences (OUAS), School of Engineering and Natural Resources, Mechanical Engineering Department to get local companies to offer project works to mechanical engineering students. The concept is based on organizing a local event or online event for the companies to come to OUAS campus to present their challenges needing engineering students to solve. The companies are then competing, selling, or pitching their problem for engineering students as the engineering students will then individually select the most interesting cases to be solved, and which has linkage to potential summer job and thesis work opportunities if projects are successful. The concept has proven to be successful, and it has been established as traditional event with many companies returning to the pitching event annually to get their industry problems solved by group of motivated engineering students.

Development of a Hypoxia-Activated Trehalose Diester for the Treatment of Solid Tumours

<p><b>The potential of bacterial cell wall components in the treatment of various cancers was initially realised in the late 1800s during pioneering work with Coley’s toxins. Since this preliminary work, efforts have been concentrated on the isolation and identification of bacterial components that lead to tumour regression. Trehalose dimycolates (TDMs) are compounds isolated from the M. tuberculosis cell wall and are known to activate macrophages to give a polarised Th1 immune response resulting in reduced tumour burden. Consequently, TDMs have shown great promise in the treatment of solid tumours.</b></p> <p>In this thesis, work is presented towards the synthesis of trehalose glycolipid prodrugs that will be specifically activated inside the hypoxic tumour microenvironment, and thereby lead to a more selective form of cancer therapy. These hypoxia-activated trehalose glycolipids incorporate a nitroimidazole trigger that fragments upon enzymatic reduction (in the absence of oxygen) to give the active glycolipid. Throughout the course of this work, it was determined that the nitroimidazole trigger group could not be directly attached to the glycolipid and thus, an alternative carbonate-linker strategy was explored through the use of a reporter fluoroprobe. The validity of this approach was determined in various enzyme and cell-based assays.</p>

Ultrafast Spectroscopy for Printable Photovoltaics

<p>The development of efficient and low cost photovoltaic technologies is key to a more sustainable energy pathway for future generations. Research efforts aimed at improving the performance of organic photovoltaic (OPV) materials have resulted in a continuous growth in power conversion efficiency (PCE) over time, with a recent maximum PCE value of 18.22% in a single bulk heterojunction device. However, further improved efficiency, stability and cost reduction are required in order for OPVs to succeed in the market. To produce better performing OPV devices in a rational way, it is necessary to understand the relationships between material properties (e.g. energy levels, recombination rates, charge carrier mobilities) and the photovoltaic parameters. This requires combining different fundamental techniques, such as spectroscopic, electrical and structural studies of the materials. In this thesis work we contribute to the understanding of the mechanisms of charge photo-current generation in OPV layers by using transient absorption spectroscopy (TAS) to directly measure the fate of the photo-excited species created upon light absorption. In particular, we contribute to the understanding of the dynamical properties of tightly bound, interfacial charge-transfer (CT) states at the donor:acceptor heterojunction. We disentangle the contributions from individual transient species to the overall TAS signal via the soft-modelling algorithm known as Multivariate Curve Resolution by Alternating Least Squares (MCR-ALS), and we use simple kinetic models to retrieve associated kinetic rates. Our first study explores the photo-physics of a family of polymers derived from the low-band-gap alternating copolymer PTBT where the sulphur atom in the thiadiazole unit was substituted with oxygen or selenium. The literature shows that replacing a single atom in the donor or acceptor unit of a polymer donor can cause large changes in the photovoltaic parameters, which cannot be explained considering only the variations in the optical band-gap. Opposite results have been reported on systems where a sulfur atom is replaced by selenium, and spectroscopic studies were lacking. Our TAS results on PTBO and PTBSe systems explain the superior photovoltaic performance of the original sulfur-containing variant PTBT, highlighting the low tolerance of these materials to backbone substitutions. In both PTBO and PTBSe systems, we identify strong recombination of geminate CT pairs as the major limiting factor of the Jsc and FF photovoltaic parameters. This is attributed to unfavourable electronic and conformational properties at the donor:acceptor interface. In the particular case of PTBSe:PC61BM, the recombination pathway of CT states with triplet character into the triplet exciton manifold is facilitated by the heavy atom effect, in addition to a highly intermixed morphology. Our second study comprises the spectroscopic comparison between fullerene and nonfullerene (NFA) OPV layers. The PCE of OPV devices was reaching a plateau in past years, which was overcomed thanks to the development of high efficiency NFA acceptors. Here, we compare charge generation and recombination between three systems featuring the same polymer donor PPDT2FBT matched with three different acceptors, namely the fullerene acceptor PC70BM, the small molecule nonfullerene acceptor NIDCS-HO and the polymeric acceptor N2200. Our results provide insight on the processes that limit the performance of each device, showing that small molecule NFA are promising acceptors, since morphology and disorder, the factors that we have found to be limiting the device performance, could potentially be tuned for the development of more efficient materials. For the all-polymer device based on the N2200 acceptor, we find that both geminate and nongeminate recombination are limiting the photovoltaic performance. Lastly, we investigate charge carrier dynamics in a series of solar devices composed predominantly of C60 and small amounts of organic small molecule donors, where their CT state energies are systematically varied. The well-defined microstructure in low-donor-content OPV blends makes it easier to correlate macroscopic properties to molecular parameters. Our results, in combination with time-delayed collection field (TDCF), and external quantum efficiency measurements (EQE) measurements at different bias performed by our collaborators, allow us to identify geminate recombination as the major loss channel. We find that the dynamics of the CT decay are connected to the CT state energy via the energy-gap law. In this way, the energy of the CT state is identified as the main parameter determining the efficiency of photocurrent generation in these morphologically well-defined donor:acceptor blends. Overall, the contributions in this thesis work demonstrate how TAS measurements can provide valuable information to construct a comprehensive picture of the underpinning mechanisms of charge photo-current generation in OPV layers, in particular by isolating the dynamical properties of interfacial charge-transfer (CT) states at the donor:acceptor heterojunction via modelling.</p>

Development of a Hypoxia-Activated Trehalose Diester for the Treatment of Solid Tumours

<p><b>The potential of bacterial cell wall components in the treatment of various cancers was initially realised in the late 1800s during pioneering work with Coley’s toxins. Since this preliminary work, efforts have been concentrated on the isolation and identification of bacterial components that lead to tumour regression. Trehalose dimycolates (TDMs) are compounds isolated from the M. tuberculosis cell wall and are known to activate macrophages to give a polarised Th1 immune response resulting in reduced tumour burden. Consequently, TDMs have shown great promise in the treatment of solid tumours.</b></p> <p>In this thesis, work is presented towards the synthesis of trehalose glycolipid prodrugs that will be specifically activated inside the hypoxic tumour microenvironment, and thereby lead to a more selective form of cancer therapy. These hypoxia-activated trehalose glycolipids incorporate a nitroimidazole trigger that fragments upon enzymatic reduction (in the absence of oxygen) to give the active glycolipid. Throughout the course of this work, it was determined that the nitroimidazole trigger group could not be directly attached to the glycolipid and thus, an alternative carbonate-linker strategy was explored through the use of a reporter fluoroprobe. The validity of this approach was determined in various enzyme and cell-based assays.</p>

Ultrafast Spectroscopy for Printable Photovoltaics

<p>The development of efficient and low cost photovoltaic technologies is key to a more sustainable energy pathway for future generations. Research efforts aimed at improving the performance of organic photovoltaic (OPV) materials have resulted in a continuous growth in power conversion efficiency (PCE) over time, with a recent maximum PCE value of 18.22% in a single bulk heterojunction device. However, further improved efficiency, stability and cost reduction are required in order for OPVs to succeed in the market. To produce better performing OPV devices in a rational way, it is necessary to understand the relationships between material properties (e.g. energy levels, recombination rates, charge carrier mobilities) and the photovoltaic parameters. This requires combining different fundamental techniques, such as spectroscopic, electrical and structural studies of the materials. In this thesis work we contribute to the understanding of the mechanisms of charge photo-current generation in OPV layers by using transient absorption spectroscopy (TAS) to directly measure the fate of the photo-excited species created upon light absorption. In particular, we contribute to the understanding of the dynamical properties of tightly bound, interfacial charge-transfer (CT) states at the donor:acceptor heterojunction. We disentangle the contributions from individual transient species to the overall TAS signal via the soft-modelling algorithm known as Multivariate Curve Resolution by Alternating Least Squares (MCR-ALS), and we use simple kinetic models to retrieve associated kinetic rates. Our first study explores the photo-physics of a family of polymers derived from the low-band-gap alternating copolymer PTBT where the sulphur atom in the thiadiazole unit was substituted with oxygen or selenium. The literature shows that replacing a single atom in the donor or acceptor unit of a polymer donor can cause large changes in the photovoltaic parameters, which cannot be explained considering only the variations in the optical band-gap. Opposite results have been reported on systems where a sulfur atom is replaced by selenium, and spectroscopic studies were lacking. Our TAS results on PTBO and PTBSe systems explain the superior photovoltaic performance of the original sulfur-containing variant PTBT, highlighting the low tolerance of these materials to backbone substitutions. In both PTBO and PTBSe systems, we identify strong recombination of geminate CT pairs as the major limiting factor of the Jsc and FF photovoltaic parameters. This is attributed to unfavourable electronic and conformational properties at the donor:acceptor interface. In the particular case of PTBSe:PC61BM, the recombination pathway of CT states with triplet character into the triplet exciton manifold is facilitated by the heavy atom effect, in addition to a highly intermixed morphology. Our second study comprises the spectroscopic comparison between fullerene and nonfullerene (NFA) OPV layers. The PCE of OPV devices was reaching a plateau in past years, which was overcomed thanks to the development of high efficiency NFA acceptors. Here, we compare charge generation and recombination between three systems featuring the same polymer donor PPDT2FBT matched with three different acceptors, namely the fullerene acceptor PC70BM, the small molecule nonfullerene acceptor NIDCS-HO and the polymeric acceptor N2200. Our results provide insight on the processes that limit the performance of each device, showing that small molecule NFA are promising acceptors, since morphology and disorder, the factors that we have found to be limiting the device performance, could potentially be tuned for the development of more efficient materials. For the all-polymer device based on the N2200 acceptor, we find that both geminate and nongeminate recombination are limiting the photovoltaic performance. Lastly, we investigate charge carrier dynamics in a series of solar devices composed predominantly of C60 and small amounts of organic small molecule donors, where their CT state energies are systematically varied. The well-defined microstructure in low-donor-content OPV blends makes it easier to correlate macroscopic properties to molecular parameters. Our results, in combination with time-delayed collection field (TDCF), and external quantum efficiency measurements (EQE) measurements at different bias performed by our collaborators, allow us to identify geminate recombination as the major loss channel. We find that the dynamics of the CT decay are connected to the CT state energy via the energy-gap law. In this way, the energy of the CT state is identified as the main parameter determining the efficiency of photocurrent generation in these morphologically well-defined donor:acceptor blends. Overall, the contributions in this thesis work demonstrate how TAS measurements can provide valuable information to construct a comprehensive picture of the underpinning mechanisms of charge photo-current generation in OPV layers, in particular by isolating the dynamical properties of interfacial charge-transfer (CT) states at the donor:acceptor heterojunction via modelling.</p>

Análisis térmico de los elementos de sujeción del núcleo de un reactor trifásico

In this thesis work the temperature distribution in the frame bolts of a 5 MVA, 115 kV, 60 Hz, three-phase five-limbs shunt reactor is obtained utilizing the finite element method (FEM) and the commercial ANSYS Maxwell software. This because the reactor actually failed while it was running, the failure occurred progressively as the screw insulation was damaged and caused an unwanted temperature rise. A time-harmonic analysis is performed to compute the magnetic field distribution in the reactor and the power losses in the frame bolts. A three-dimensional (3-D) shunt reactor model is utilized, and Maxwell’s equations are solved utilizing scalar and vectorial magnetic potentials. The 3-D electromagnetic shunt reactor model is validated by comparing the value of inductance measured in the laboratory with the value of inductance computed in the 3-D FE simulation. In addition, the core losses computed in the FE simulation are compared with the core losses measured in the laboratory. This thesis work is important for transformer manufacturers which requires an adequate shunt reactor model to analyze it under different operation conditions and to optimize the actual design.

Partial Replacement of Pumice Stone in Concrete As Coarse Aggregate Material

In design of concrete structures, concrete plays an important role in the contemporary background as raw material for construction has been decreased. Therefore construction industry has acquaint with novel methods by making use of the available waste material for partial replacement by using alternative aggregates instead of ordinary aggregates. In this study, pumice stone is used as replacement materials for concrete where it is found in the abyssal of the red clay or in deepest portion of the ocean, and partially replacing by Pumice, blends with cement. The physical, mechanical and durability properties of concrete was investigated by conduction compressive strength and tensile strength on the ordinary and replaced concrete with varied percentage of pumice from 5% to 30%. It’s obsereved that environmental and economical benefits can be achieved if waste materials can be used to replace the coarse aggregate in order to use the waste materials effectively in areas with abundant availability of materials. This thesis work on the effectiveness of partial substitutions of pumice for coarse aggregate in producing adequate strength gain. In the present thesis work comparison of fresh concrete and hardened properties of concrete for both conventional concrete and Replaced concrete for varying percentage of replacement of pumice stone to coarse aggregate and based on the experimental results, it’s concluded that 25% partial replacement by pumice gives maximum compresive strength.

Playful Assembly

<p><b>Porirua is a small city I lived in from the age of ten to sixteen. It is the home to Wellington region’s best indoor go-karting track and fallen victim to urban sprawl. The first of four of my homes in this area was in the newly developed Aotea block and at the time it was the first house on the street. My four year old brother would sit and watch diggers and tractors all day, and in the afternoon we climbed them. All this destruction was intensely entertaining to a child. The devastation hit when the neighbour’s house got built, along with the rest of the street, in what felt like a week. Just like that, the glory days were over. We moved a couple years after this closer into the Whitby community. Aotea development was so new all it had was houses, I wouldn’t even call them homes. My mum got sick of travelling to Whitby all the time for milk and so on, so we eventually moved closer to the town. I could walk or bike to and from school. It was all so close; the dairy, friends’ houses, football park, playground, skatepark, everything! The glory days were back and better than ever.</b></p> <p>This move into an established community felt more like home. The simple rituals of walking to the dairy to get milk (and a lolly bag) became something I regularly enjoyed. The accessibility of amenities gave me independence and made life easier. The ‘home’ broke through the boundaries of the house and into the park, the biked streets and the football pitch. If one can feel at home within a whole community then why build new houses separate from established towns? All on their lonesome, dependent on cars and with diggers for neighbours.</p> <p>This thesis re-conceives Porirua as a playful assembly. With an emphasis on cultural wealth, this process establishes an architectural language promoting Porirua’s development towards a creative city. Cultural wealth is a term which gives priority to the cultural layer of the city, it emphasises creation rather than consumption. Creativity sits at the heart of this layer making it a crucial element of the creative city. The wealth of culture in Porirua comes from its depth of diversity; in Maori, Pasifika and Pakeha and others coming together. While the specific cultures aren’t emphasised, the importance lies within this diversity. This is one of the reasons I chose the Porirua CBD as the site for my thesis.</p> <p>My playful process crosses paths with art, architecture and urban perspectives to develop a visual language emphasising creation within the city. The search for my own creative voice lends itself to the importance of self-expression within the city. Through this thesis work, I wanted to encourage people to more openly produce self-expressive work. I recognise that the city already has these processes and the products and processes of my creative voice target the creation of these spaces giving them priority and emphasis in the city. This thesis aims to create a welcoming, inclusive environment for people to create. Within the urban realm an alternative view is presented holding creativity at the heart of the city rather than economy.</p>

Playful Assembly

<p><b>Porirua is a small city I lived in from the age of ten to sixteen. It is the home to Wellington region’s best indoor go-karting track and fallen victim to urban sprawl. The first of four of my homes in this area was in the newly developed Aotea block and at the time it was the first house on the street. My four year old brother would sit and watch diggers and tractors all day, and in the afternoon we climbed them. All this destruction was intensely entertaining to a child. The devastation hit when the neighbour’s house got built, along with the rest of the street, in what felt like a week. Just like that, the glory days were over. We moved a couple years after this closer into the Whitby community. Aotea development was so new all it had was houses, I wouldn’t even call them homes. My mum got sick of travelling to Whitby all the time for milk and so on, so we eventually moved closer to the town. I could walk or bike to and from school. It was all so close; the dairy, friends’ houses, football park, playground, skatepark, everything! The glory days were back and better than ever.</b></p> <p>This move into an established community felt more like home. The simple rituals of walking to the dairy to get milk (and a lolly bag) became something I regularly enjoyed. The accessibility of amenities gave me independence and made life easier. The ‘home’ broke through the boundaries of the house and into the park, the biked streets and the football pitch. If one can feel at home within a whole community then why build new houses separate from established towns? All on their lonesome, dependent on cars and with diggers for neighbours.</p> <p>This thesis re-conceives Porirua as a playful assembly. With an emphasis on cultural wealth, this process establishes an architectural language promoting Porirua’s development towards a creative city. Cultural wealth is a term which gives priority to the cultural layer of the city, it emphasises creation rather than consumption. Creativity sits at the heart of this layer making it a crucial element of the creative city. The wealth of culture in Porirua comes from its depth of diversity; in Maori, Pasifika and Pakeha and others coming together. While the specific cultures aren’t emphasised, the importance lies within this diversity. This is one of the reasons I chose the Porirua CBD as the site for my thesis.</p> <p>My playful process crosses paths with art, architecture and urban perspectives to develop a visual language emphasising creation within the city. The search for my own creative voice lends itself to the importance of self-expression within the city. Through this thesis work, I wanted to encourage people to more openly produce self-expressive work. I recognise that the city already has these processes and the products and processes of my creative voice target the creation of these spaces giving them priority and emphasis in the city. This thesis aims to create a welcoming, inclusive environment for people to create. Within the urban realm an alternative view is presented holding creativity at the heart of the city rather than economy.</p>

Wavelet application in acoustic emission signal detection of wire related events in pipeline

This thesis establishes an automatic classification program for the signal detection work in pipeline inspection. Time-scale analysis provides the basic methodology of this thesis work. The wavelet transform is implemented in the program for filtering out the majority of noise and detect needed signals. As a popular nondestructive test, acoustic emission (AE) testing has been widely used in many physical and engineering fields such as leak detection and pipeline inspection. Among those applied AE tests, a common problem is to extract the physical features of the ideal events, so as to detect similar signals. In acoustic signal processing, those features can be represented as joint time frequency distribution. However, classical signal processing methods only give global information on either time or frequency domain, while local information is lots. Although the short-time Fourier transform (STFT) is developed to analyze time and frequency details simultaneously, it can only achieve limited precision. Other time-frequency methods are also applied in AE signal processing, but they all have the problem of resolution and time consuming. Wavelet transform is a time-scale technique with adaptable precision, which makes better feature extraction and detail detection. This thesis is an application of wavelet transform in AE signal detection where various noise exists. The wavelet transform with Morelet wavelet as the mother wavelet provides the basis of the program for auto classification in this thesis work. Finally the program is tested with two industrial projects to verify the workability of wavelet transforms and the reliability of the developed auto classifiers.