Experimental detection of sudden stiffness change in a structural system employing Laser Doppler Vibrometry

Sudden changes in the stiffness of a structure are often indicators of structural damage. Detection of such sudden stiffness change from the vibrations of structures is important for Structural Health Monitoring (SHM) and damage detection. Non-contact measurement of these vibrations is a quick and efficient way for successful detection of sudden stiffness change of a structure. In this paper, we demonstrate the capability of Laser Doppler Vibrometry to detect sudden stiffness change in a Single Degree Of Freedom (SDOF) oscillator within a laboratory environment. The dynamic response of the SDOF system was measured using a Polytec RSV-150 Remote Sensing Vibrometer. This instrument employs Laser Doppler Vibrometry for measuring dynamic response. Additionally, the vibration response of the SDOF system was measured through a MicroStrain G-Link Wireless Accelerometer mounted on the SDOF system. The stiffness of the SDOF system was experimentally determined through calibrated linear springs. The sudden change of stiffness was simulated by introducing the failure of a spring at a certain instant in time during a given period of forced vibration. The forced vibration on the SDOF system was in the form of a white noise input. The sudden change in stiffness was successfully detected through the measurements using Laser Doppler Vibrometry. This detection from optically obtained data was compared with a detection using data obtained from the wireless accelerometer. The potential of this technique is deemed important for a wide range of applications. The method is observed to be particularly suitable for rapid damage detection and health monitoring of structures under a model-free condition or where information related to the structure is not sufficient.

Realisable climate change narratives in public discourse: an East/West comparative analysis of environmental, social, and corporate governance (ESG) as a response to global climate change

This thesis looks at how non-experts develop an opinion on climate change, and how those opinions could be changed by public discourse. I use Hubert Dreyfus’ account of skill acquisition to distinguish between experts and non-experts. I then use a combination of Walter Fisher’s narrative paradigm and the hermeneutics of Paul Ricœur to explore how non-experts form opinions, and how public narratives can provide a point of critique. In order to develop robust narratives, they must be financially realistic. I therefore consider the burgeoning field of environmental, social, and corporate governance (ESG) analysis as a way of informing realistic public narratives. I identify a potential problem with this approach: the Western assumptions of ESG analysis might make for public narratives that are not convincing to a non-Western audience. I then demonstrate how elements of the Chinese tradition, the Confucian, Neo-Confucian, and Daoist schools, as presented by David Hall and Roger Ames, can provide alternative assumptions to ESG analysis so that the public narratives will be more culturally adaptable. This research contributes to the discipline by bringing disparate traditions together in a unique way, into a practical project with a view towards applications. I conclude by considering avenues for further research.

Leadership in the community sector: promoting collaboration and social change in Belfast

Community development is centrally concerned with people in communities working together to achieve a common goal, that is, to collaborate, whether within local geographical communities, in communities of shared interests or among groups sharing a common identity. Its overarching goal is one of progressive transformational social change. As Belfast transitions from a conflict to a post-conflict society, there is a need for greater, more effective work at local community level in order to address a range of ongoing social and economic issues facing communities, including high levels of disadvantage and division. Given the significance of leadership in building effective collaboration and the centrality of collaboration for community development, it is important to understand how leadership is currently enacted and what kinds of leadership are required to support communities to collaborate effectively to bring about social change. This thesis thus centers on the kind of leadership practised and required to support collaboration for social change within the community sector in Belfast, a city that contains an estimated 28% of the total number of community and voluntary sector (CVS) organisations in Northern Ireland (Northern Ireland Council for Voluntary Action, 2012). Through a series of qualitative, in-depth interviews with people playing leadership roles in local communities, the study critically explores and analyses their experiences and perceptions in relation to leadership and collaboration. Community development in Belfast today is practised within a wider context of neoliberal policies, characterised by austerity and public spending cuts. Whilst not the only influencing factor, this context has had a particular and profound impact on the nature and role of community development practised, and on the kind of leadership enacted within it. The space for reflection and transformative action appears to be shrinking as the contraction of resources to support community development in local communities continues unabated. Those playing leadership roles increasingly find themselves compelled to spend time seeking resources and managing complex funding arrangements rather than focusing on the social change dimensions of their work. Collaboration as promoted by the state seems to have become an instrumental tactic used to implement its austerity measures and curtail the potential of the community sector. Despite this, local leaders are driving initiatives that attempt to push back, helping the sector refocus on its transformational goals of social change. To do this requires support. Those playing leadership roles require resources, including time, to encourage and enable communities to reconnect with the purpose and underpinning values of community development. Leaders also need support to develop and promote new, progressive narratives and visions and pursue these through building collaboration and solidarity.

Cellular ROS imaging with hydro-Cy3 dye is strongly influenced by mitochondrial membrane potential

Background: Hydrocyanines are widely used as fluorogenic probes to monitor reactive oxygen species (ROS) generation in cells. Their brightness, stability to autoxidation and photobleaching, large signal change upon oxidation, pH independence and red/near infrared emission are particularly attractive for imaging ROS in live tissue. Methods: Using confocal fluorescence microscopy we have examined an interference of mitochondrial membrane potential (ΔΨm) with fluorescence intensity and localisation of a commercial hydro-Cy3 probe in respiring and non-respiring colon carcinoma HCT116 cells. Results: We found that the oxidised (fluorescent) form of hydro-Cy3 is highly homologous to the common ΔΨm-sensitive probe JC-1, which accumulates and aggregates only in ‘energised’ negatively charged mitochondrial matrix. Therefore, hydro-Cy3 oxidised by hydroxyl and superoxide radicals tends to accumulate in mitochondrial matrix, but dissipates and loses brightness as soon as ΔΨm is compromised. Experiments with mitochondrial inhibitor oligomycin and uncoupler FCCP, as well as a common ROS producer paraquat demonstrated that signals of the oxidised hydro-Cy3 probe rapidly and strongly decrease upon mitochondrial depolarisation, regardless of the rate of cellular ROS production. Conclusions: While analysing ROS-derived fluorescence of commercial hydrocyanine probes, an accurate control of ΔΨm is required. General significance: If not accounted for, non-specific effect of mitochondrial polarisation state on the behaviour of oxidised hydrocyanines can cause artefacts and data misinterpretation in ROS studies.

Potential Arctic tundra vegetation shifts in response to changing temperature, precipitation and permafrost thaw

Over the past decades, vegetation and climate have changed significantly in the Arctic. Deciduous shrub cover is often assumed to expand in tundra landscapes, but more frequent abrupt permafrost thaw resulting in formation of thaw ponds could lead to vegetation shifts towards graminoid-dominated wetland. Which factors drive vegetation changes in the tundra ecosystem are still not sufficiently clear. In this study, the dynamic tundra vegetation model, NUCOM-tundra (NUtrient and COMpetition), was used to evaluate the consequences of climate change scenarios of warming and increasing precipitation for future tundra vegetation change. The model includes three plant functional types (moss, graminoids and shrubs), carbon and nitrogen cycling, water and permafrost dynamics and a simple thaw pond module. Climate scenario simulations were performed for 16 combinations of temperature and precipitation increases in five vegetation types representing a gradient from dry shrub-dominated to moist mixed and wet graminoid-dominated sites. Vegetation composition dynamics in currently mixed vegetation sites were dependent on both temperature and precipitation changes, with warming favouring shrub dominance and increased precipitation favouring graminoid abundance. Climate change simulations based on greenhouse gas emission scenarios in which temperature and precipitation increases were combined showed increases in biomass of both graminoids and shrubs, with graminoids increasing in abundance. The simulations suggest that shrub growth can be limited by very wet soil conditions and low nutrient supply, whereas graminoids have the advantage of being able to grow in a wide range of soil moisture conditions and have access to nutrients in deeper soil layers. Abrupt permafrost thaw initiating thaw pond formation led to complete domination of graminoids. However, due to increased drainage, shrubs could profit from such changes in adjacent areas. Both climate and thaw pond formation simulations suggest that a wetter tundra can be responsible for local shrub decline instead of shrub expansion.

Rural change south of the river Bride in counties Cork and Waterford: the surveyors' evidence 1716–1851

Estate studies in Irish historical geography have been often designed to confirm or contrast local trends of development with those previously identified at the regional or sub-regional level. To date, little attention has been awarded to estate maps in studies of rural landscape change. It is a theme of this paper that the results yielded from a careful study of such estate maps can throw light on the results of the activities of the majority of estate residents. In this regard, it is fortunate that at Lismore surveys of the estate in 1716–17 and 1773–4 have survived, and a nineteenth century dimension is added by an analysis of the Valuation Office maps for 1851. This work is focused on a study of critical indicators of change, notably leasing arrangements, farm size, rate and type of enclosure, infrastructural development and settlement growth. These changes are reviewed within the framework of the dialectic that developed between landlord or landlord-inspired management policies and the forces released locally by the vast bulk of the population. Broadly this analysis indicates some of the potential rewards which may be secured by detailed scrutiny of estate maps in conjunction with other estate records.