13,185 research outputs found
A non-gaussian continuous state space model for asset degradation
No full textThe degradation model plays an essential role in asset life prediction and condition based maintenance. Various degradation models have been proposed. Within these models, the state space model has the ability to combine degradation data and failure event data. The state space model is also an effective approach to deal with the multiple observations and missing data issues. Using the state space degradation model, the deterioration process of assets is presented by a system state process which can be revealed by a sequence of observations. Current research largely assumes that the underlying system development process is discrete in time or states. Although some models have been developed to consider continuous time and space, these state space models are based on the Wiener process with the Gaussian assumption. This paper proposes a Gamma-based state space degradation model in order to remove the Gaussian assumption. Both condition monitoring observations and failure events are considered in the model so as to improve the accuracy of asset life prediction. A simulation study is carried out to illustrate the application procedure of the proposed model
Dr. Lin Sun, CAU, March 2013
No full textThis video is a conversation with Dr. Lin Sun. Dr. Sun talks about an exhibit at the Woodruff Library titled "At The Boundary." Jordan Moore, AUC Woodruff Library, is the interviewer
Understanding data management in asset management: A survey
No full textData and information management systems have become a cornerstone for almost all operations of an organisation by providing quality, timely data for decision support. Information systems have progressed to cover a wide variety of asset management areas including asset registration, financial management, process scheduling and control, materials management, maintenance management, condition monitoring, risk management, reliability management, and safety management. Past studies into data management within asset management have focused on understanding why specific systems or specific data management processes are implemented in a firm. However, there has been little investigation into the broader picture of such asset management information systems and their overall data integration strategies. An exploratory, cross-sectional survey was conducted during 2007 and 2008 that explored a variety of data management issues in asset management across more than forty organisations. The survey research questions addressed practices in information system selection, data warehousing, integration, and data retention. Results show the significant adoption of information systems and data warehousing across different industries; the primary use of information systems to streamline business processes and enhance reporting; and the strong desire for improved system integration for next generation asset management information systems
Identifying different determinants of asset life
No full textEngineering asset management (EAM) involves the life cycle management of engineered physical assets. Within EAM, accurate asset life prediction is an essential scientific research problem. Asset life is defined and evaluated based on four aspects: physical, social and environmental, economic, and technological. Each aspect is represented by a set of determinants. A number of models have been developed to predict the life of an asset; however, most of these models are focused on one aspect. A model jointly considering different aspects of asset life is still highly desired because asset life is a complex function of multiple aspects and determinants. The identification of these determinants is an essential task in asset life prediction. However, a comprehensive literature review has not revealed these sets of determinants and their relationships. The synergies or relationships among these determinants are complex. In order to identify these relationships, existing models are reviewed and analysed to extract the determinants as a foundation for further research. In this paper, these determinants are extracted and identified by surveying and analysing existing models in each aspect of asset life. Furthermore, to model interactions and interrelationships among the determinants, the system dynamics approach is proposed to establish a preliminary influence diagram, which is the first attempt to model the relationships of determinants of each aspect
Latent degradation indicator estimation using condition monitoring information
No full textAsset health prediction is imperative to optimal asset management. Online and offline inspections can provide useful information for predicting asset health. The information from an asset health inspection can be divided into two types. (1) Direct indicators which directly determine failures (e.g. the thickness of a brake pad, or the wear in a component) and (2) indirect indicators which are not related to failures directly (e.g. vibration signals or oil analysis results). The direct indicators can provide more precise reference for the maintenance strategy determination. However, these direct degradation indicators are often technically or economically impossible to inspect frequently and accurately. The indirect indicators, on the other hand, can be acquired more easily using various condition monitoring techniques. This paper proposes two continuous state space models to estimate and predict direct degradation indicators using indirect degradation indicators. The two continuous state space models adopt the Wiener process and the Gamma process respectively. The Expectation Maximization (EM) algorithms based on the modified Kalman smoother and the modified particle smoother are used to estimate the parameters of the proposed models. The application process of the EM algorithms and the characteristics of the state space models are illuminated through a simulation study. Finally, a case study using the data from an accelerated test of a gear box is conducted to justify the feasibility of the proposed models
An Analysis of <i>Judge Lin</i>
No full textBiography of Lin Wen Zhong Gong has another way to call, that is Judge Lin. The leading character is Lin Ze-Xu. This book is based on functionary experience of Lin Ze-Xu, with the captivating plots of court case, helping by highly skilled military attach\uc3\ua9s and chivalrous knights, and the history facts of Opium War. It makes Lin Ze-Xu\ue2s Confucian temperament and tragic mood more, also contrasts with author\ue2s sorrow and furiousness for the politics at the time. History, court case, martial arts\ue2\ua6\ue2\ua6etc. are essence of this book and it broadens the way of this writing style.
The topic of the thesis is \ue2An Analysis of Judge Lin\ue2. The following thesis will be divided into six different chapters. The introduction is Chapter one of the thesis, which is including researching motive and purpose, literature review of predecessors, researching version by existing information, raising questions, choosing research methods and arranging chapters. In chapter Two, I discuss the study of characters of Lin Ze-Xu, also makes a deep analysis of author\u27s purpose of writing him. In chapter Three, I analyze supporting actors and actress. Meanwhile, I illustrate author\u27s purpose of writing supporting actress because the author had different manner to describe supporting actress. Moving to the Chapter Four, I mainly focus on the plots of Judge Lin, and organize cases of Lin Ze-Xu and his subordinates to understand features of cases. In Chapter Five, I represent the causes of Opium War. China and England had difference of opinions of opium. Therefore, it is easier to comprehend what the author\u27s purpose is. In the last chapter I summarize the main points of the preceding chapters and confirm particularity of Judge Lin
Leveraging engineering asset data : strategic priorities, data types and informational outcomes
No full textA common complaint heard within the engineering asset community is that while the capacity for data storage increases, the quality of ever increasing amounts of data remains poor. We propose a new model of engineering asset data management that helps explain why data collected by organizations frequently fails to assist in effective engineering asset management. The model situates a four component typology of engineering\ud
data between institutional drivers (e.g. organizational culture; organizational strategy; organizational life-cycle; consequence of asset failure) and asset management outcomes. We argue these outcomes (regulatory compliance; time-based maintenance; condition-based asset management; capacity development) are functions\ud
not only of the data collected by an organization, but its capacity to leverage that data. We develop a model suggesting that institutional drivers dictate the data requirements of engineering asset intensive firms, typically\ud
at the cost of data requirements for different phases in the asset's life-cycle. This paper will assist practitioners to re-conceptualize the manner in which they view their data, the manner in which it is utilized, and provide a better understanding of data and its intended outcomes. This will allow a better prioritization of data collection\ud
activities and offer an improved insight into ways in which engineering data may be better transformed into informational and knowledge outcomes
Structural damage localization in slab-on-girder bridges using vibration characteristics
No full textThis paper uses dynamic computer simulation techniques to develop and apply a procedure using non-destructive methods for damage assessment in slab-on-girder bridges. In addition to changes in natural frequencies, this multi-criteria procedure incorporates two methods, namely the modal flexibility and the modal strain energy method. Using the numerically simulated modal data obtained through finite element analysis software, algorithms based on flexibility and strain energy changes before and after damage are obtained and used as the indices for the assessment of structural health state. The application of the two proposed methods in literature is limited to beam-type and plate-type elements separately. The multi-criteria based damage identification procedure is therefore developed for slab-on-girder bridges. The application of the approach is demonstrated through numerical simulation studies of a single-span simply supported slab-on-girder bridge with seven damage scenarios corresponding to type of deck damage and girder damage individually. Results show that the proposed multi-criteria method incorporating modal flexibility and modal strain energy method is \ud
effective in damage assessment in this type of bridge superstructure
Best practice engineering asset cultures : a pilot study
No full textengineering and maintenance departments. Those wishing to implement contemporary maintenance regimes (e.g. Condition Based Maintenance) are often encouraged to develop "appropriate cultures" to support the new method's introduction. Unfortunately these same publications often fail to articulate the cultural values required to support the efforts of those behind the implementation. In the broader literature only a limited\ud
number of case examples document the cultural values held by engineering asset intensive firms and how they contribute to their success (or failure). Consequently a gap exists in our knowledge of what engineering cultures currently are, and what might constitute a best practice engineering asset culture. We report the findings of a pilot study investigating the perceived ideal characteristics of engineering asset cultures.\ud
Engineering managers, consultants and academics (n=47) were surveyed as to what they saw were essential attributes of both engineering cultures and of engineering asset personnel. Valued cultural elements included those orientated around safety and quality and commercial orientations. Valued individual attributes included\ud
openness to change, interpersonal skills and contentiousness. The paper concludes with a discussion regarding the development of a best practice cultural framework
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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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