title: Damage identification in skeletal structures: A dynamic stiffness approach

authors: De Los Rios Giraldo, Julian Octavio

subjects: Damage identification

abstract: The present work is devoted to investigate ways of identifying cracks in skeletal structures by frequency monitoring. This is a challenging problem as the number of cracks, their severity and location all need to be found. It has been shown that roving bodies with rotary inertia could be used to find the total number of cracks and their locations without any knowledge of their severity. The Dynamic Stiffness Method was chosen due to its capabilities in enabling an exact solution while facilitating addition of new elements such as springs and masses to the structure in the same way as in the approximate Finite Element Method (FEM). Using the Dynamic Stiffness Matrices (DSM), it was possible to derive an interesting and useful relationship between the determinants of the DSM of the following: the original undamaged structure, the cracked structure and the structure with a hinge at the potential crack location. This relationship is a simple equation which gives the determinant of the cracked structure as the sum of the determinant of the undamaged structure multiplied by the rotational stiffness of the beam at the crack and the determinant of a structure with a hinge at the same crack location.

Experimental results from literature are used to validate the application of the found features in beam structures and frameworks to identify damages or dynamic properties. A semi-experimental methodology is proposed to treat multi-cracked structures where, as a first step, the roving inertia method is used to identify the number and location of the cracks in a simple way without the need to perform any calculations or theoretical analysis. The theoretical basis of this method is explained using the DSM. Experimental work was carried out on a cantilever beam to verify the applicability of the roving inertia method but no conclusive results were obtained. Further experimental investigations are needed to study the practical feasibility of the method. It is hoped that once the locations of all cracks are identified, the severity of the cracks can be found using the frequency measurements as the determinants of the DSM are linear functions of crack severity.

text: Damage identification in skeletal structures: A dynamic stiffness approach The present work is devoted to investigate ways of identifying cracks in skeletal structures by frequency monitoring. This is a challenging problem as the number of cracks, their severity and location all need to be found. It has been shown that roving bodies with rotary inertia could be used to find the total number of cracks and their locations without any knowledge of their severity. The Dynamic Stiffness Method was chosen due to its capabilities in enabling an exact solution while facilitating addition of new elements such as springs and masses to the structure in the same way as in the approximate Finite Element Method (FEM). Using the Dynamic Stiffness Matrices (DSM), it was possible to derive an interesting and useful relationship between the determinants of the DSM of the following: the original undamaged structure, the cracked structure and the structure with a hinge at the potential crack location. This relationship is a simple equation which gives the determinant of the cracked structure as the sum of the determinant of the undamaged structure multiplied by the rotational stiffness of the beam at the crack and the determinant of a structure with a hinge at the same crack location.

Experimental results from literature are used to validate the application of the found features in beam structures and frameworks to identify damages or dynamic properties. A semi-experimental methodology is proposed to treat multi-cracked structures where, as a first step, the roving inertia method is used to identify the number and location of the cracks in a simple way without the need to perform any calculations or theoretical analysis. The theoretical basis of this method is explained using the DSM. Experimental work was carried out on a cantilever beam to verify the applicability of the roving inertia method but no conclusive results were obtained. Further experimental investigations are needed to study the practical feasibility of the method. It is hoped that once the locations of all cracks are identified, the severity of the cracks can be found using the frequency measurements as the determinants of the DSM are linear functions of crack severity.

year: 2017

title: Structured articulation of knowledge: The influence of question response structure on recipient attitude

authors: Bircham-Connolly, Heather Jayne

subjects: knowledge sharing

abstract: Business today is faced with discontinuity and unpredictable change, which makes
many of the structured processes of yesteryear redundant or obsolete. Process-based
transactions are being replaced with technology and increasingly organisations are
recognising the importance of proactively managing their knowledge transactions, to
remain competitive. While research on knowledge sharing is gaining the attention of
researchers, almost invariably their focus has been on the factors influencing
knowledge transfer at the macro-level in large multi-national organisations. Few
have attempted to unravel the complexities of individual-to-individual micro-level
knowledge sharing and those that have, for the most part have directed their
investigations towards exploring factors that enhance or impede the source individual
sharing their knowledge, rather than the recipient's receiving of knowledge. While
questioning is implicit in knowledge sharing there are assumptions that underpin the
structure of a question and these assumptions affect both the source and the
recipient.
This study investigates how the structure of a question posed to a source individual
when eliciting knowledge, influences the attitude of a recipient individual towards the
knowledge they receive from the question response. Drawing upon theoretical
assumptions that underpin question structure, three hypotheses are posed to
compare binary, open-ended and directed question responses. To test the
hypotheses a progression of three independent studies were performed using
laboratory and field experiments. The first study conducted in a laboratory, used a
contrived scenario case as the knowledge context and the second study replicated
this experiment in the field. The last study conducted in a single organisation, used
real organisational knowledge as the knowledge context.
Recipients of shared knowledge were found to be more favourably disposed towards
question responses that were structured in a complex manner; open-ended and
directed question responses were more favoured than binary question responses.
ii
There was no difference in recipient attitude between open-ended and directed
question responses and recipient attitude towards the shared knowledge was found
to be positively related to their intention to use the knowledge in the future.
These findings are of significance as they illustrate the importance of structuring
questions in a manner that is consistent with recipients of the shared knowledge
being more favourably disposed towards the knowledge they have received. In an
environment of ambiguity, complexity and uncertainty where decisions are nonprogrammed,
strategic and imperative to the competitiveness of the organisation, no
longer is the binary 'Yes' or 'No' compliance or audit style question, with its implicit
assumptions, sufficient to elicit knowledge. It is important to recognise that often we
do not know what we need to know until it is shared by someone. Further, when
shared knowledge is cognitively processed with our current knowledge base, the new
knowledge is likely to facilitate more informed decision-making. The more
favourably disposed the recipient is towards the knowledge the more likely it is that
they will use it in the future; knowledge is transferred.

text: Structured articulation of knowledge: The influence of question response structure on recipient attitude Business today is faced with discontinuity and unpredictable change, which makes
many of the structured processes of yesteryear redundant or obsolete. Process-based
transactions are being replaced with technology and increasingly organisations are
recognising the importance of proactively managing their knowledge transactions, to
remain competitive. While research on knowledge sharing is gaining the attention of
researchers, almost invariably their focus has been on the factors influencing
knowledge transfer at the macro-level in large multi-national organisations. Few
have attempted to unravel the complexities of individual-to-individual micro-level
knowledge sharing and those that have, for the most part have directed their
investigations towards exploring factors that enhance or impede the source individual
sharing their knowledge, rather than the recipient's receiving of knowledge. While
questioning is implicit in knowledge sharing there are assumptions that underpin the
structure of a question and these assumptions affect both the source and the
recipient.
This study investigates how the structure of a question posed to a source individual
when eliciting knowledge, influences the attitude of a recipient individual towards the
knowledge they receive from the question response. Drawing upon theoretical
assumptions that underpin question structure, three hypotheses are posed to
compare binary, open-ended and directed question responses. To test the
hypotheses a progression of three independent studies were performed using
laboratory and field experiments. The first study conducted in a laboratory, used a
contrived scenario case as the knowledge context and the second study replicated
this experiment in the field. The last study conducted in a single organisation, used
real organisational knowledge as the knowledge context.
Recipients of shared knowledge were found to be more favourably disposed towards
question responses that were structured in a complex manner; open-ended and
directed question responses were more favoured than binary question responses.
ii
There was no difference in recipient attitude between open-ended and directed
question responses and recipient attitude towards the shared knowledge was found
to be positively related to their intention to use the knowledge in the future.
These findings are of significance as they illustrate the importance of structuring
questions in a manner that is consistent with recipients of the shared knowledge
being more favourably disposed towards the knowledge they have received. In an
environment of ambiguity, complexity and uncertainty where decisions are nonprogrammed,
strategic and imperative to the competitiveness of the organisation, no
longer is the binary 'Yes' or 'No' compliance or audit style question, with its implicit
assumptions, sufficient to elicit knowledge. It is important to recognise that often we
do not know what we need to know until it is shared by someone. Further, when
shared knowledge is cognitively processed with our current knowledge base, the new
knowledge is likely to facilitate more informed decision-making. The more
favourably disposed the recipient is towards the knowledge the more likely it is that
they will use it in the future; knowledge is transferred.

year: 2007

title: Governance of water based on responsible use – an elegant solution?‎

authors: Te Aho, Linda

abstract: The inspiration for this chapter is a proposal said to represent "a paradigm shift" for the governance of freshwater, articulated by Sir Edward Taihakurei Durie in 2014. ² Arising out of challenges to a government plan to sell its shares in powergenerating companies,³ the Durie proposal has at its heart a possibility for reconciling Maori rights and interests and wider general interests in freshwater. It is based on the assumption that Maori and the general public have a legitimate interest in the natural water regimes of the country. However, the source of the interest is not the same. The Maori interest is proprietary and is sourced in their status as the indigenous first peoples of the land who were guaranteed continuation of their tino rangatiratanga in respect of their lands and waters in Te Tiriti o Waitangi.⁴ The public interest is sourced in the British laws that superimposed Maori laws through processes of colonisation. The heart of the Durie proposal is that those utilising water for commercial purposes should be charged and that an independent commission would be responsible for overseeing charging and revenue collection and disbursement. A proportion of the funds would be allocated to Maori authorities in recognition of the Maori interest. Whether in public or Maori hands, the funds should be applied to the maintenance or improvement of the natural water bodies of the area or the assurance of water supplies to all homes. In short, the proposal focuses upon responsibility.

text: Governance of water based on responsible use – an elegant solution?‎ The inspiration for this chapter is a proposal said to represent "a paradigm shift" for the governance of freshwater, articulated by Sir Edward Taihakurei Durie in 2014. ² Arising out of challenges to a government plan to sell its shares in powergenerating companies,³ the Durie proposal has at its heart a possibility for reconciling Maori rights and interests and wider general interests in freshwater. It is based on the assumption that Maori and the general public have a legitimate interest in the natural water regimes of the country. However, the source of the interest is not the same. The Maori interest is proprietary and is sourced in their status as the indigenous first peoples of the land who were guaranteed continuation of their tino rangatiratanga in respect of their lands and waters in Te Tiriti o Waitangi.⁴ The public interest is sourced in the British laws that superimposed Maori laws through processes of colonisation. The heart of the Durie proposal is that those utilising water for commercial purposes should be charged and that an independent commission would be responsible for overseeing charging and revenue collection and disbursement. A proportion of the funds would be allocated to Maori authorities in recognition of the Maori interest. Whether in public or Maori hands, the funds should be applied to the maintenance or improvement of the natural water bodies of the area or the assurance of water supplies to all homes. In short, the proposal focuses upon responsibility.

year: 2019