Tip timing techniques for turbomachinery HCF condition monitoring

High Cycle Fatigue (HCF) has been established as the major common failure mode in the US Air Force large fleet of aero-engines. Corrective measures for this failure mode in themselves deliver additional technical, managerial and cost pressures. Two responses are in place to address this problem; risk mitigation through accelerated engine development fixes and technology transition through targeted and focussed R&D studies. It is the latter that is of interests and is discussed in this paper. Aero-engine blade vibrations of sufficient amplitude cause High Cycle Fatigue, which reduces blade life. In order to observe this vibration a non-intrusive monitoring system is sought. The vibration can be detected by measuring blade tip timing since in the presence of vibration the blade timing will differ slightly from the passing time calculated from rotor speed. Work done to investigate the suitability of a commercially available capacitance probe tip clearance measurement system for application as a non-intrusive turbomachinery blade tip timing measurement device is reported. Capacitance probe results are correlated with simultaneously measure strain gauge results and the performance of the capacitance system in measuring blade vibration is analysed. The growing interest in blade high cycle fatigue within the aerospace industry, and an approach to monitoring their condition are discussed as an extension to the above study. The suggested approach is based upon the tip-timing method, using non-contact optical probes located around the engine’s casing. Two current tip-timing techniques are suggested for the purpose. The techniques are summarised, the experimental validation of both methods outlined, and the approach taken to investigate the potential use as a condition monitoring tool described. The paper is concluded with a discussion of the future use of tiptiming as a condition monitoring tool

Predicting peak daily maximum 8 h ozone and linkages to emissions and meteorology in Southern California using machine learning methods (SoCAB-8HR V1.0)

The growing abundance of data is conducive to using numerical methods to relate air quality, meteorology and emissions to address which factors impact pollutant concentrations. Often, it is the extreme values that are of interest for health and regulatory purposes (e.g., the National Ambient Air Quality Standard for ozone uses the annual maximum daily fourth highest 8 h average (MDA8) ozone), though such values are the most challenging to predict using empirical models. We developed four different computational models, including the generalized additive model (GAM), multivariate adaptive regression splines, random forest, and support vector regression, to develop observation-based relationships between the fourth highest MDA8 ozone in the South Coast Air Basin and precursor emissions, meteorological factors and large-scale climate patterns. All models had similar predictive performance, though the GAM showed a relatively higher R2 value (0.96) with a lower root mean square error and mean bias.</p

Finite-gap Solutions of the Vortex Filament Equation: Isoperiodic Deformations

We study the topology of quasiperiodic solutions of the vortex filament equation in a neighborhood of multiply covered circles. We construct these solutions by means of a sequence of isoperiodic deformations, at each step of which a real double point is "unpinched" to produce a new pair of branch points and therefore a solution of higher genus. We prove that every step in this process corresponds to a cabling operation on the previous curve, and we provide a labelling scheme that matches the deformation data with the knot type of the resulting filament.Comment: 33 pages, 5 figures; submitted to Journal of Nonlinear Scienc

A new doubly discrete analogue of smoke ring flow and the real time simulation of fluid flow

Modelling incompressible ideal fluids as a finite collection of vortex filaments is important in physics (super-fluidity, models for the onset of turbulence) as well as for numerical algorithms used in computer graphics for the real time simulation of smoke. Here we introduce a time-discrete evolution equation for arbitrary closed polygons in 3-space that is a discretisation of the localised induction approximation of filament motion. This discretisation shares with its continuum limit the property that it is a completely integrable system. We apply this polygon evolution to a significant improvement of the numerical algorithms used in Computer Graphics.Comment: 15 pages, 3 figure

Tissue inhibitor of metalloproteinase-1 (TIMP-1) regulates mesenchymal stem cells through let-7f microRNA and Wnt/β-catenin signaling

Tissue inhibitor of metalloproteinases 1 (TIMP-1) is a matrix metalloproteinase (MMP)-independent regulator of growth and apoptosis in various cell types. The receptors and signaling pathways that are involved in the growth factor activities of TIMP-1, however, remain controversial. RNA interference of TIMP-1 has revealed that endogenous TIMP-1 suppresses the proliferation, metabolic activity, and osteogenic differentiation capacity of human mesenchymal stem cells (hMSCs). The knockdown of TIMP-1 in hMSCs activated the Wnt/β-catenin signaling pathway as indicated by the increased stability and nuclear localization of β-catenin in TIMP-1–deficient hMSCs. Moreover, TIMP-1 knockdown cells exhibited enhanced β-catenin transcriptional activity, determined by Wnt/β-catenin target gene expression analysis and a luciferase-based β-catenin– activated reporter assay. An analysis of a mutant form of TIMP-1 that cannot inhibit MMP indicated that the effect of TIMP-1 on β-catenin signaling is MMP independent. Furthermore, the binding of CD63 to TIMP-1 on the surface of hMSCs is essential for the TIMP-1–mediated effects on Wnt/β-catenin signaling. An array analysis of microRNAs (miRNAs) and transfection studies with specific miRNA inhibitors and mimics showed that let-7f miRNA is crucial for the regulation of β-catenin activity and osteogenic differentiation by TIMP-1. Let-7f was up-regulated in TIMP-1–depleted hMSCs and demonstrably reduced axin 2, an antagonist of β-catenin stability. Our results demonstrate that TIMP-1 is a direct regulator of hMSC functions and reveal a regulatory network in which let-7f modulates Wnt/β-catenin activity

Conservation laws for vacuum tetrad gravity

Ten conservation laws in useful polynomial form are derived from a Cartan form and Exterior Differential System (EDS) for the tetrad equations of vacuum relativity. The Noether construction of conservation laws for well posed EDS is introduced first, and an illustration given, deriving 15 conservation laws of the free field Maxwell Equations from symmetries of its EDS. The Maxwell EDS and tetrad gravity EDS have parallel structures, with their numbers of dependent variables, numbers of generating 2-forms and generating 3-forms, and Cartan character tables all in the ratio of 1 to 4. They have 10 corresponding symmetries with the same Lorentz algebra, and 10 corresponding conservation laws.Comment: Final version with additional reference

Western Diet-Fed, Aortic-Banded Ossabaw Swine: A Preclinical Model of Cardio-Metabolic Heart Failure.

The development of new treatments for heart failure lack animal models that encompass the increasingly heterogeneous disease profile of this patient population. This report provides evidence supporting the hypothesis that Western Diet-fed, aortic-banded Ossabaw swine display an integrated physiological, morphological, and genetic phenotype evocative of cardio-metabolic heart failure. This new preclinical animal model displays a distinctive constellation of findings that are conceivably useful to extending the understanding of how pre-existing cardio-metabolic syndrome can contribute to developing HF

Assessment of Minimal Residual Disease in Standard-Risk AML

BACKGROUND: Despite the molecular heterogeneity of standard-risk acute myeloid leukemia (AML), treatment decisions are based on a limited number of molecular genetic markers and morphology-based assessment of remission. Sensitive detection of a leukemia-specific marker (e.g., a mutation in the gene encoding nucleophosmin [NPM1]) could improve prognostication by identifying submicroscopic disease during remission. METHODS: We used a reverse-transcriptase quantitative polymerase-chain-reaction assay to detect minimal residual disease in 2569 samples obtained from 346 patients with NPM1-mutated AML who had undergone intensive treatment in the National Cancer Research Institute AML17 trial. We used a custom 51-gene panel to perform targeted sequencing of 223 samples obtained at the time of diagnosis and 49 samples obtained at the time of relapse. Mutations associated with preleukemic clones were tracked by means of digital polymerase chain reaction. RESULTS: Molecular profiling highlighted the complexity of NPM1-mutated AML, with segregation of patients into more than 150 subgroups, thus precluding reliable outcome prediction. The determination of minimal-residual-disease status was more informative. Persistence of NPM1-mutated transcripts in blood was present in 15% of the patients after the second chemotherapy cycle and was associated with a greater risk of relapse after 3 years of follow-up than was an absence of such transcripts (82% vs. 30%; hazard ratio, 4.80; 95% confidence interval [CI], 2.95 to 7.80; P<0.001) and a lower rate of survival (24% vs. 75%; hazard ratio for death, 4.38; 95% CI, 2.57 to 7.47; P<0.001). The presence of minimal residual disease was the only independent prognostic factor for death in multivariate analysis (hazard ratio, 4.84; 95% CI, 2.57 to 9.15; P<0.001). These results were validated in an independent cohort. On sequential monitoring of minimal residual disease, relapse was reliably predicted by a rising level of NPM1-mutated transcripts. Although mutations associated with preleukemic clones remained detectable during ongoing remission after chemotherapy, NPM1 mutations were detected in 69 of 70 patients at the time of relapse and provided a better marker of disease status. CONCLUSIONS: The presence of minimal residual disease, as determined by quantitation of NPM1-mutated transcripts, provided powerful prognostic information independent of other risk factors. (Funded by Bloodwise and the National Institute for Health Research; Current Controlled Trials number, ISRCTN55675535.)

Protocols for calibrating multibeam sonar

Author Posting. © Acoustical Society of America, 2005. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 117 (2005): 2013-2027, doi:10.1121/1.1869073.Development of protocols for calibrating multibeam sonar by means of the standard-target method is documented. Particular systems used in the development work included three that provide the water-column signals, namely the SIMRAD SM2000/90- and 200-kHz sonars and RESON SeaBat 8101 sonar, with operating frequency of 240 kHz. Two facilities were instrumented specifically for the work: a sea well at the Woods Hole Oceanographic Institution and a large, indoor freshwater tank at the University of New Hampshire. Methods for measuring the transfer characteristics of each sonar, with transducers attached, are described and illustrated with measurement results. The principal results, however, are the protocols themselves. These are elaborated for positioning the target, choosing the receiver gain function, quantifying the system stability, mapping the directionality in the plane of the receiving array and in the plane normal to the central axis, measuring the directionality of individual beams, and measuring the nearfield response. General preparations for calibrating multibeam sonars and a method for measuring the receiver response electronically are outlined. Advantages of multibeam sonar calibration and outstanding problems, such as that of validation of the performance of multibeam sonars as configured for use, are mentioned.Support by the National Science Foundation through Award No. OCE-0002664, NOAA through Grant No. NA97OG0241, and the Cooperative Institute for Climate and Ocean Research (CICOR) through NOAA Contract No. NA17RJ1223 is acknowledged

The effects of probiotic bacteria on glycaemic control in overweight men and women: a randomised controlled trial

Background/Objectives: Evidence from animal and in vitro models suggest a role of probiotic bacteria in improving glycaemic control and delaying the onset of type 2 diabetes. However, the evidence from controlled trials in humans is limited. The objective was to determine if the probiotic bacteria L. acidophilus La5 and B. animalis subsp lactis Bb12, supplemented in a whole food (yoghurt) or isolated (capsules) form, can improve biomarkers of glycaemic control. Subjects/methods: Following a 3-week washout period, 156 overweight men and women over 55 years (mean age: 67±8 years; mean body mass index (31±4 kg/m2) were randomized to a 6-week double-blinded parallel study. The four intervention groups were: (A) probiotic yoghurt plus probiotic capsules; (B) probiotic yoghurt plus placebo capsules; (C) control milk plus probiotic capsules; and (D) control milk plus placebo capsules. Outcome measurements, including fasting glucose, insulin, glycated haemoglobin and Homoeostasis Model Assessment of Insulin Resistance (HOMA-IR), were performed at baseline and week 6. Results: Relative to the milk-control group, probiotic yoghurt resulted in a significantly higher HOMA-IR (0.32±0.15, P=0.038), but did not have a significant effect on the other three measures of glycaemic control (P>0.05). Relative to placebo capsules, probiotic capsules resulted in a significantly higher fasting glucose (0.15±0.07 mmol/l, P=0.037), with no significant effect on the other three measures of glycaemic control (P>0.05). Further analyses did not identify other variables as contributing to these adverse findings. Conclusions: Data from this study does not support the hypothesis that L. acidophilus La5 and B. animalis subsp lactis Bb12, either in isolated form or as part of a whole food, benefit short-term glycaemic control. Indeed, there is weak data for an adverse effect of these strains on glucose homoeostasis