RCFA for Recurring Impeller Failures in a 4

LectureA Root Cause Failure Analysis (RCFA) for repeated impeller blade failures in a five stage centrifugal propane compressor is described. The initial failure occurred in June 2007 with a large crack found in one blade on the third impeller and two large pieces released from adjacent blades on the fourth impeller. An RCFA was performed to determine the cause of the failures. The failure mechanism was identified to be high cycle fatigue. Several potential causes related to the design, manufacture, and operation of the compressor were examined. The RCFA concluded that the design and manufacture were sound and there were no conclusive issues with respect to operation. A specific root cause was never identified. In June 2009, a second case of blade cracking occurred with a piece once again released from a single blade on the fourth impeller. Due to the commonality with the previous instance this was identified as a repeat failure. Specifically, both cases had occurred in the same compressor whereas, two compressors operating in identical service in Copyright © 2011 by Turbomachinery Laboratory, Texas A&M University adjacent Liquefied natural Gas (LNG) trains had not encountered the problem. A second RCFA was accordingly launched with the ultimate objective of preventing further repeated failures. Both RCFA teams were established comprising of engineers from the End User (RasGas), the OEM (Elliott Group) and an independent consultancy (Southwest Research Institute). The scope of the current investigation included a detailed metallurgical assessment, impeller modal frequency assessment, steady and unsteady computational fluid dynamics (CFD) assessment, finite element analyses (FEA), fluid structure interaction (FSI) assessment, operating history assessment and a comparison change analysis. By the process of elimination, the most probable causes were found to be associated with: · vane wake excitation of either the impeller 1-diameter cover/blades modal frequency or the blade leading edge modal frequency from mistuning · mist carry over from third side load upstream scrubber · end of curve operation in the compressor rear sectio

Sparse Plus Low Rank Matrix Decomposition: A Discrete Optimization Approach

We study the Sparse Plus Low-Rank decomposition problem (SLR), which is the problem of decomposing a corrupted data matrix into a sparse matrix of perturbations plus a low-rank matrix containing the ground truth. SLR is a fundamental problem in Operations Research and Machine Learning which arises in various applications, including data compression, latent semantic indexing, collaborative filtering, and medical imaging. We introduce a novel formulation for SLR that directly models its underlying discreteness. For this formulation, we develop an alternating minimization heuristic that computes high-quality solutions and a novel semidefinite relaxation that provides meaningful bounds for the solutions returned by our heuristic. We also develop a custom branch-and-bound algorithm that leverages our heuristic and convex relaxations to solve small instances of SLR to certifiable (near) optimality. Given an input $n$-by-$n$ matrix, our heuristic scales to solve instances where $n=10000$ in minutes, our relaxation scales to instances where $n=200$ in hours, and our branch-and-bound algorithm scales to instances where $n=25$ in minutes. Our numerical results demonstrate that our approach outperforms existing state-of-the-art approaches in terms of rank, sparsity, and mean-square error while maintaining a comparable runtime

Session I

Session 1: 6:00pm-7:00pm Dr. Yongan Wu and Dr. Nicholas de Villiers, Disorder and Excavating the Future from the Past,” Meredith Wilson, “Dystopian Visions in The Hunger Games and Atlas Shrugged,” and Cory Chamberlain, “Ideologies of the Insane: A Reading of Gogol and Althusser.” Respondents: Dr. Betsy Nies, Professor Linda Howel

RCFA for Recurring Impeller Failures in a 4

LectureA Root Cause Failure Analysis (RCFA) for repeated impeller blade failures in a five stage centrifugal propane compressor is described. The initial failure occurred in June 2007 with a large crack found in one blade on the third impeller and two large pieces released from adjacent blades on the fourth impeller. An RCFA was performed to determine the cause of the failures. The failure mechanism was identified to be high cycle fatigue. Several potential causes related to the design, manufacture, and operation of the compressor were examined. The RCFA concluded that the design and manufacture were sound and there were no conclusive issues with respect to operation. A specific root cause was never identified. In June 2009, a second case of blade cracking occurred with a piece once again released from a single blade on the fourth impeller. Due to the commonality with the previous instance this was identified as a repeat failure. Specifically, both cases had occurred in the same compressor whereas, two compressors operating in identical service in Copyright © 2011 by Turbomachinery Laboratory, Texas A&M University adjacent Liquefied natural Gas (LNG) trains had not encountered the problem. A second RCFA was accordingly launched with the ultimate objective of preventing further repeated failures. Both RCFA teams were established comprising of engineers from the End User (RasGas), the OEM (Elliott Group) and an independent consultancy (Southwest Research Institute). The scope of the current investigation included a detailed metallurgical assessment, impeller modal frequency assessment, steady and unsteady computational fluid dynamics (CFD) assessment, finite element analyses (FEA), fluid structure interaction (FSI) assessment, operating history assessment and a comparison change analysis. By the process of elimination, the most probable causes were found to be associated with: · vane wake excitation of either the impeller 1-diameter cover/blades modal frequency or the blade leading edge modal frequency from mistuning · mist carry over from third side load upstream scrubber · end of curve operation in the compressor rear sectio

Concert recording 2018-11-12

[Track 1]. Quatour en forme de sonatine. I. Allegro grazioso [Track 2]. II. Andantino tranquilo [Track 3]. III. Scherzando quasi presto [Track 4]. IV. Allegro moderato (a la Russe) / Antoine Simon -- [Track 5]. 4 miniatures. I. Salutations [Track 6]. II. Toccata [Track 7]. III. Lament [Track 8]. IV. Jubilation / Michael Forbes -- [Track 9]. Dance suite. I. Dancisca, for Anthony (Anthony Tudor) [Track 10]. II. Waltz, for Agnes (Agnes de Mille) [Track 11]. III. Bi-tango, for Mischa (Mikhail Baryshnikov) [Track 12]. IV. Two-step, for Mr. B (George Balanchine) [Track 13]. V. Mtv, for Jerry (Jerome Robbins) / Leonard Bernstein -- [Track 14]. Colchester fantasy. I. The rose and the crown [Track 15]. II. The marquis of Granby [Track 16]. III. The dragoon [Track 17]. IV. The red lion / Eric Ewazen

Timing is everything, but does it really matter? Impact of 8-weeks morning versus evening iron supplementation in ballet and contemporary dancers

The effectiveness of a morning versus evening oral iron supplement strategy to increase iron stores was explored. Ballet and contemporary dancers with serum ferritin (sFer) \u3c 50 g/L (n = 14), were supplemented daily with 105 mg elemental oral iron in either the morning (FeAM) or evening (FePM) for 8 weeks. A control group (n = 6) with sFer \u3e 50 g/L were given no supplement over the same period. Dancers’ sFer were measured at baseline and post-intervention. Assessment of daily training load, dietary intake, and menstruation were made. A significant interaction (p \u3c 0.001) showed the within group sFer change over the 8-week intervention in FeAM (+25.9 ± 10.5 g/L) and FePM, (+22.3 ± 13.6 g/L) was significantly different to CON (−30.17 ± 28.7 g/L; both p = 0.001). This change was not different between FeAM and FePM (p = 0.778). sFer levels within FeAM and FePM significantly increased over the 8-weeks; however, they significantly decreased in the CON group (all p \u3c 0.05). Post-intervention sFer levels were no longer different between the three groups (p \u3e 0.05). Training load, dietary intake, and number of menstrual cycles incurred were similar between FeAM and FePM (p \u3e 0.05). Oral iron supplementation in either the morning or evening appears equally effective in increasing sFer levels in dancers with sub-optimal iron status