A Periodicity Metric for Assessing Maintenance Strategies

Organised by: Cranfield UniversityThe maintenance policy in manufacturing systems is devised to reset the machines functionality in an economical fashion in order to keep the products quality within acceptable levels. Therefore, there is a need for a metric to evaluate and quantify function resetting due to the adopted maintenance policy. A novel metric for measuring the functional periodicity has been developed using the complexity theory. It is based on the rate and extent of function resetting. It can be used as an important criterion for comparing the different maintenance policy alternatives. An industrial example is used to illustrate the application of the new metric.Mori Seiki – The Machine Tool Company; BAE Systems; S4T – Support Service Solutions: Strategy and Transitio

Comprehensive Complexity-Based Failure Modeling for Maintainability and Serviceability

Organised by: Cranfield UniversityFailures are the primary triggers for repair and maintenance actions. A clear definition of failure events is important in order to improve maintainability and serviceability. A comprehensive complexity-based mathematical definition of failure is introduced. The applicability of the developed failure model to different complexity definitions is discussed. A new metric is introduced to capture the change in complexity associated with function degradation. A case study is presented to illustrate the application of the new failure definition and metric. The developed approach for failure modeling can be used for maintenance planning.Mori Seiki – The Machine Tool Company; BAE Systems; S4T – Support Service Solutions: Strategy and Transitio

Synthesis, analytical features, and biological relevance of 5-(3′,4′-Dihydroxyphenyl)-γ-valerolactone, a microbial metabolite derived from the catabolism of dietary flavan-3-ols

The physiological significance of 5-(3′,4′-dihydroxyphenyl)- γ-valerolactone, an important metabolite derived from the catabolism of flavan-3-ols by gut microbiota, has been often overlooked due to the lack of the commercial standard. In the present work, this metabolite has been chemically synthesized, and its analytical parameters and antioxidant capacity have been determined in comparison to other chemical analogues [isomer 3-(3′,4′-dihydroxyphenyl)-δ-valerolactone and γ-valerolactone] and other structurally related compounds [(+)-catechin, (-)-epicatechin, and 3-(3,4-dihydroxyphenyl)-propionic acid]. The synthesized compound was also used to perform a targeted analysis in samples collected during the in vitro fermentation of a grape seed flavan-3-ol extract with human fecal microbiota from three healthy volunteers. The time-course formation of 5-(3′,4′-dihydroxyphenyl)-γ-valerolactone revealed large interindividual differences among volunteers, with concentrations ranging from 3.31 to 77.54 μM at 10 h of fermentation. These results are further discussed in view of the scarce reports quantifying 5-(3′,4′-dihydroxyphenyl) -γ-valerolactone in in vitro fermentation studies, and pharmacokinetic and intervention studies. © 2011 American Chemical Society.Peer Reviewe