1,721,058 research outputs found
Development of a method to classify and analyse the composition of mixed waste materials in real-time
Full text linkLonghurst, Philip J. - Associate SupervisorThere is a need for innovative technologies to classify and monitor the
composition of solid waste in real-time. This research project has highlighted
which information is required to improve current process designs. It also identified
visible spectrum cameras as the solution that can better inform waste
composition and quality without requiring complementing technologies. The
experiments applied deep learning methods to classify the materials based on
their images, and a method to analyse the composition of mixed waste was
developed.
There is a high variability in the appearance of waste materials in the context of
a material recovery facility. An image capture setup using multiple cameras and
light sources was implemented and tested to acquire a representative set of
images. The hardware captures images from different angles, with enhanced
shadow details, and different exposure levels. Image processing software further
augmented the data by rotating and changing the images resolutions. The images
were converted to greyscale to increase the method robustness without affecting
classification performance.
Deep convolutional neural networks were trained on the augmented datasets.
The trained networks obtained state-of-the-art performance when tested and
validated for the task of waste material classification. Based on this, a
composition analysis methodology was developed and tested with mixed material
samples. The methodology provides results as accurate as current manual
solutions, but it can analyse a waste stream on a conveyor belt in real-time. The
findings and observations from the experimental results contribute to knowledge
in three main areas: data capture, data processing, and deep learning.
This thesis presents the progressive development of the methodology and
discusses different applications for waste management. The composition
analysis can provide real-time waste data to improve the overall efficiency of the
waste treatment industry. This information can be also used by stakeholders for
better decision-making in the future.PhD in Energy and Powe
Investigation of the impact of trace elements on anaerobic volatile fatty acid degradation using a fractional factorial experimental design
Full text linkThe requirement of trace elements (TE) in anaerobic digestion process is widely documented. However, little is understood regarding the specific requirement of elements and their critical concentrations under different operating conditions such as substrate characterisation and temperature.In this study, a flask batch trial using fractional factorial design is conducted to investigate volatile fatty acids (VFA) anaerobic degradation rate under the influence of the individual and combined effect of six TEs (Co, Ni, Mo, Se, Fe and W). The experiment inoculated with food waste digestate, spiked with sodium acetate and sodium propionate both to 10 g/l. Thisis followed by the addition of a selection of the six elements in accordance with a 26-2 fractional factorial principle. The experiment is conducted in duplicate and the degradation of VFA is regularly monitored.Factorial effect analysis on the experimental results reveals that within these experimental conditions, Se has a key role in promoting the degradation rates of both acetic and propionic acids; Mo and Co are found to have a modest effect on increasing propionic acid degradation rate. It is also revealed that Ni shows some inhibitory effects on VFA degradation, possibly due to its toxicity. Additionally, regression coefficients for the main and second order effects are calculated to establish regression models for VFA degradation
Quantifying the percentage of methane formation via acetoclastic and syntrophic acetate oxidation pathways in anaerobic digesters
Full text linkAmmonia concentration is one of the key factors influencing the methanogenic community composition and dominant methanogenic pathway in anaerobic digesters. This study adopted a radiolabelling technique using [2-14C] acetate to investigate the relationship between total ammonia nitrogen (TAN) and the methanogenic pathway. The radiolabelling experiments determined the ratio of 14CO2 and 14CH4 in the biogas which was used to quantitatively determine the percentage of CH4 derived from acetoclastic and syntrophic acetate oxidation routes, respectively.
This technique was performed on a selection of mesophilic digesters representing samples of low to high TAN concentrations (0.2–11.1 g kg−1 wet weight). In high TAN digesters, the ratio between 14CO2 and 14CH4 was in the range 2.1–3.0; indicating 68–75% of methane was produced via the hydrogenotrophic route; whereas in low ammonia samples the ratio was 0.1–0.3, indicating 9–23% of methane was produced by the hydrogenotrophic route. These findings have been confirmed further by phylogenetic studies
Influencing factors and mechanisms of local government green development behaviour: evidence from China
Full text linkLonghurst, Philip - Associate SupervisorGreen development has become an important strategy for local governments to
achieve greater sustainability, and adopting green development behaviours has
significant implications for local governments in addressing the relationship
between the environment and the economy. Previous research demonstrated
that the unique characteristics of green development practices have received
considerable attention from scholars. Most studies have highlighted green
development practices in the private sector, although the adoption of green
development practices in the public sector remains understudied. Current
research on green development behaviour in the public sector primarily reflects,
at the individual level, the green behaviour of employees and, at the
organisational level, the green purchasing behaviour of a particular government
department. The discussion of local government green development behaviour
is not predominant. Therefore, this thesis proposes that a detailed understanding
of the processes and specific practices of local government green development
behaviours may be essential for local governments to improve the effectiveness
of implementing sustainable practices.
Although existing studies have addressed the influencing factors that lead to the
adoption of sustainable development by local governments, there needs to be a
more systematic theoretical analysis of the underlying mechanisms adopted by
local governments to achieve green development behaviours. Accordingly, this
thesis aims to explore the factors that influence the implementation of green
development behaviours by local governments and the mechanisms of influence
between the factors. This study draws on mixed methods to develop two studies.
The first is a qualitative study that explores local government green development
behaviour and its influencing factors. It applies various data collection methods,
including semi-structured interviews and document analysis. Fifty-three officials
from local government departments related to green development in China’s
Jiangsu province were interviewed, and the data were analysed using a grounded
theory method. The second is a quantitative study. Seven hundred twenty-two
valid questionnaires were collected, and the model proposed in the first study
with Structural Equation Modelling (SEM). The findings illustrate how the
interactions between various factors shape the green development behaviour of
local governments.
The main findings show that: (1) local government green development behaviour
is a kind of behavioural change, which can be divided into local government green
development policy formulation and implementation. (2) The three main
influences on local governments’ green development behaviours include internal
driving factors, external environmental pressures, and the basis of regional green
development. (3) Internal driving factors and external environmental pressure can
influence local governments’ green development behaviours. (4) Internal driving
factors mediate the relationship between external environmental pressure and
green development behaviour. The basis of regional green development has a
moderating effect on the relationship between internal driving factors and green
development behaviours, as well as the relationship between external
environmental pressures and green development behaviours.
This thesis provides a framework that supports local government behaviour's
decision-making process on the managerial implications. Paper I analyses the
specific processes and practices of local government green development
behaviour, Paper II constructs a theoretical model of local government green
development behaviour, and Paper III examines the mechanisms by which
various factors influence local green development behaviour. At a broader level,
this thesis enriches and expands the research content of sustainable practices in
the public sector. It also provides novel insights for local governments to
formulate effective green development policies, which will help them develop
green development directions and implement green development behaviours to
promote more remarkable sustainable development in the region.PhD in Desig
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Development of a cost-benefit model for a landfill gas infrastructure development
No full textLandfilling solid urban waste is the prevailing method of solid waste disposal
worldwide. Biodegradable waste is disposed of in landfills which then
decompose often over many decades releasing landfill gas. This gas, is mainly
composed of methane and carbon dioxide, both are greenhouse gases which
actively contribute to global warming. Indeed, methane has a global warming
potential 21 times more than CO2. These environmental problems associated
with landfill gas demand for current energy needs highlights the potential of the
recovery of landfill gas as a significant alternative to fossil fuels.
This study sets out to determine the extent to which the economic value of
power generation from landfill gas differs from the market value of the CO2
equivalent landfill gas. To achieve this purpose, a cost-benefit model has been
created in order to identify the different capital, power generation and
operational costs associated with a landfill operational site. In the same manner,
the main sources of revenue have been determined: sales of electricity to the
grid and carbon credits.
Three different scenarios have been analyzed: small, medium and large landfill
sites, all of them placed in the UK. The analysis had two different appraisals:
economic and environmental. In the first one, the feasibility and profitability of
the three scenarios have been evaluated. In the latter, the amount of tonnes of
CO2 equivalent avoided to be pumped into the atmosphere has been
calculated.
The economic analysis indicates that the average capital costs for all the sites
are notably higher. Particularly, for small sites, i.e. a capacity of 1MW, where
landfill gas-to-energy projects were not profitable. On average, the Net Present
Value (NPV) of small sites was less than 0. This factor indicated that the initial
investment would not be recovered in a long period and therefore, the revenues
achieved from the implementation of LFG Collection Systems were not enough
for the operators to invest in these infrastructures.
Not only from an economic point of view, but also considering an environmental
appraisal, it can be stated that the price of selling electricity to the grid is below
the real price of avoiding methane emissions (shadow price of the carbon).
THE ANALYSIS DONE SUGGESTED THAT LARGE AND MEDIUM SITES
PROJECTS WERE VIABLE (NPV>0) WITH REDUCED ROC SUPPORT.
HOWEVER, FOR SMALLER PROJECTS MORE OPTIMISTIC REVENUES
AND COST OF CAPITAL WERE REQUIRED IN ORDER TO ACHIEVE
VIABILITY.Outgoin
Development of a cost-benefit model for a landfill gas infrastructure development
No full textLandfilling solid urban waste is the prevailing method of solid waste disposal
worldwide. Biodegradable waste is disposed of in landfills which then
decompose often over many decades releasing landfill gas. This gas, is mainly
composed of methane and carbon dioxide, both are greenhouse gases which
actively contribute to global warming. Indeed, methane has a global warming
potential 21 times more than CO2. These environmental problems associated
with landfill gas demand for current energy needs highlights the potential of the
recovery of landfill gas as a significant alternative to fossil fuels.
This study sets out to determine the extent to which the economic value of
power generation from landfill gas differs from the market value of the CO2
equivalent landfill gas. To achieve this purpose, a cost-benefit model has been
created in order to identify the different capital, power generation and
operational costs associated with a landfill operational site. In the same manner,
the main sources of revenue have been determined: sales of electricity to the
grid and carbon credits.
Three different scenarios have been analyzed: small, medium and large landfill
sites, all of them placed in the UK. The analysis had two different appraisals:
economic and environmental. In the first one, the feasibility and profitability of
the three scenarios have been evaluated. In the latter, the amount of tonnes of
CO2 equivalent avoided to be pumped into the atmosphere has been
calculated.
The economic analysis indicates that the average capital costs for all the sites
are notably higher. Particularly, for small sites, i.e. a capacity of 1MW, where
landfill gas-to-energy projects were not profitable. On average, the Net Present
Value (NPV) of small sites was less than 0. This factor indicated that the initial
investment would not be recovered in a long period and therefore, the revenues
achieved from the implementation of LFG Collection Systems were not enough
for the operators to invest in these infrastructures.
Not only from an economic point of view, but also considering an environmental
appraisal, it can be stated that the price of selling electricity to the grid is below
the real price of avoiding methane emissions (shadow price of the carbon).
THE ANALYSIS DONE SUGGESTED THAT LARGE AND MEDIUM SITES
PROJECTS WERE VIABLE (NPV>0) WITH REDUCED ROC SUPPORT.
HOWEVER, FOR SMALLER PROJECTS MORE OPTIMISTIC REVENUES
AND COST OF CAPITAL WERE REQUIRED IN ORDER TO ACHIEVE
VIABILITY.Outgoin
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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