Identification of material properties of orthotropic composite plate using hybrid non-destructive evaluation approach

Identification of material properties is one of the key issues in composite materials research. The mechanical properties of composite materials depend on diverse factors such as configuration of the laminates, constituent materials used and production method adopted. Conventional testing approach tends to be time-consuming, expensive and destructive. As an alternative, a rapid, inexpensive, hybrid and non-destructive evaluation approach which utilises experimental modal analysis and finite element analysis is proposed. Experimental modal data which consist of natural frequencies and mode shapes of an orthotropic composite plate are utilised for correlation purpose with its finite element model. This finite element model of the composite plate is continuously updated and achieves less than 5% in difference of natural frequencies and over 70% in modal assurance criterion. Material properties such as Young's moduli, inplane shear modulus and Poisson ratio of the composite plate are then successfully determined using the well-correlated FE model

Non-destructive testing and assessment of dynamic incompatibility between third-party piping and drain valve systems: An industrial case study

This paper presents the outcome of an industrial case study that involved condition monitoring of piping system that showed signs of excess fatigue due to flow-induced vibration. Due to operational requirements, a novel non-destructive assessment stratagem was adopted using different vibration analysis techniques - such as experimental modal analysis and operating deflection shapes - and complemented by visual inspection. Modal analysis carried out near a drain valve showed a dynamic weakness problem (several high-frequency flow-induced vibration frequency peaks), hence condition-based monitoring was used. This could easily be linked to design problem associated with the dynamic incompatibility due to dissimilar stiffness between two third-party supplied pipe and valve systems. It was concluded that this is the main cause for these problem types especially when systems are supplied by third parties, but assembled locally, a major cause of dynamic incompatibility. It is the local assembler's responsibility to develop skills and expertise needed to sustain the operation of these plants. This paper shows the technique used as result of one such initiative. Since high amplitude, low-frequency displacement can cause low cycle fatigue, attention must be paid to ensure flow remains as steady state as possible. The ability to assess the level of design incompatibility and the level of modification required using non-destructive testing is vital if these systems are to work continuously. © 2014 Taylor & Francis

Impact force identification with pseudo-inverse method on a lightweight structure for under-determined, even-determined and over-determined cases

Force identification using inverse technique is important especially when direct measurement through force transducer is not possible. Considering the effects of impact excitation force on the integrity of a lightweight structure, impact force identification has become the subject of several studies. A methodology utilising Operating Deflection Shape (ODS) analysis, Frequency Response Function (FRF) measurement and pseudo-inverse method to evaluate the dynamic force is presented. A rectangular plate with four ground supports was used as a test rig to simulate the motions of a simple vehicle body. By using the measured responses at remote points that are away from impact locations and measured FRFs of the test rig, unknown force locations and their time histories can be recovered by the proposed method. The performance of this approach in various cases such as under-determined, even-determined and over-determined cases was experimentally demonstrated. Good and bad combinations of response locations were selected based on the condition number of FRF matrix. This force identification method was examined under different response combinations and various numbers of response locations. It shows that in the over-determined case, good combination of response locations (i.e. low average of condition number of FRF matrix) and high number of response locations give the best accuracy of force identification result compared to under-determined and even-determined cases

Production and Decay of D_1(2420)^0 and D_2^*(2460)^0

We have investigated $D^{+}\pi^{-}$ and $D^{*+}\pi^{-}$ final states and observed the two established $L=1$ charmed mesons, the $D_1(2420)^0$ with mass $2421^{+1+2}_{-2-2}$ MeV/c$^{2}$ and width $20^{+6+3}_{-5-3}$ MeV/c$^{2}$ and the $D_2^*(2460)^0$ with mass $2465 \pm 3 \pm 3$ MeV/c$^{2}$ and width $28^{+8+6}_{-7-6}$ MeV/c$^{2}$. Properties of these final states, including their decay angular distributions and spin-parity assignments, have been studied. We identify these two mesons as the $j_{light}=3/2$ doublet predicted by HQET. We also obtain constraints on {\footnotesize $\Gamma_S/(\Gamma_S + \Gamma_D)$} as a function of the cosine of the relative phase of the two amplitudes in the $D_1(2420)^0$ decay.Comment: 15 pages in REVTEX format. hardcopies with figures can be obtained by sending mail to: [email protected]

Measurement of the branching fraction for Υ(1S)→τ+τ−\Upsilon (1S) \to \tau^+ \tau^-

We have studied the leptonic decay of the $\Upsilon (1S)$ resonance into tau pairs using the CLEO II detector. A clean sample of tau pair events is identified via events containing two charged particles where exactly one of the particles is an identified electron. We find $B(\Upsilon(1S) \to \tau^+ \tau^-) = (2.61~\pm~0.12~{+0.09\atop{-0.13}})$. The result is consistent with expectations from lepton universality.Comment: 9 pages, RevTeX, two Postscript figures available upon request, CLNS 94/1297, CLEO 94-20 (submitted to Physics Letters B

Measurement of the Decay Asymmetry Parameters in Λc+→Λπ+\Lambda_c^+ \to \Lambda\pi^+ and Λc+→Σ+π0\Lambda_c^+ \to \Sigma^+\pi^0

We have measured the weak decay asymmetry parameters (\aLC ) for two \LC\ decay modes. Our measurements are \aLC = -0.94^{+0.21+0.12}_{-0.06-0.06} for the decay mode $\Lambda_c^+ \to \Lambda\pi^+$ and \aLC = -0.45\pm 0.31 \pm 0.06 for the decay mode $\Lambda_c \to \Sigma^+\pi^0$. By combining these measurements with the previously measured decay rates, we have extracted the parity-violating and parity-conserving amplitudes. These amplitudes are used to test models of nonleptonic charmed baryon decay.Comment: 11 pages including the figures. Uses REVTEX and psfig macros. Figures as uuencoded postscript. Also available as http://w4.lns.cornell.edu/public/CLNS/1995/CLNS95-1319.p

Common variants near MC4R are associated with fat mass, weight and risk of obesity.

To identify common variants influencing body mass index (BMI), we analyzed genome-wide association data from 16,876 individuals of European descent. After previously reported variants in FTO, the strongest association signal (rs17782313, P = 2.9 x 10(-6)) mapped 188 kb downstream of MC4R (melanocortin-4 receptor), mutations of which are the leading cause of monogenic severe childhood-onset obesity. We confirmed the BMI association in 60,352 adults (per-allele effect = 0.05 Z-score units; P = 2.8 x 10(-15)) and 5,988 children aged 7-11 (0.13 Z-score units; P = 1.5 x 10(-8)). In case-control analyses (n = 10,583), the odds for severe childhood obesity reached 1.30 (P = 8.0 x 10(-11)). Furthermore, we observed overtransmission of the risk allele to obese offspring in 660 families (P (pedigree disequilibrium test average; PDT-avg) = 2.4 x 10(-4)). The SNP location and patterns of phenotypic associations are consistent with effects mediated through altered MC4R function. Our findings establish that common variants near MC4R influence fat mass, weight and obesity risk at the population level and reinforce the need for large-scale data integration to identify variants influencing continuous biomedical traits

Associations of autozygosity with a broad range of human phenotypes

In many species, the offspring of related parents suffer reduced reproductive success, a phenomenon known as inbreeding depression. In humans, the importance of this effect has remained unclear, partly because reproduction between close relatives is both rare and frequently associated with confounding social factors. Here, using genomic inbreeding coefficients (F-ROH) for >1.4 million individuals, we show that F-ROH is significantly associated (p <0.0005) with apparently deleterious changes in 32 out of 100 traits analysed. These changes are associated with runs of homozygosity (ROH), but not with common variant homozygosity, suggesting that genetic variants associated with inbreeding depression are predominantly rare. The effect on fertility is striking: F-ROH equivalent to the offspring of first cousins is associated with a 55% decrease [95% CI 44-66%] in the odds of having children. Finally, the effects of F-ROH are confirmed within full-sibling pairs, where the variation in F-ROH is independent of all environmental confounding.Peer reviewe

Genomic and phenotypic insights from an atlas of genetic effects on DNA methylation

DNA methylation quantitative trait locus (mQTL) analyses on 32,851 participants identify genetic variants associated with DNA methylation at 420,509 sites in blood, resulting in a database of >270,000 independent mQTLs.Characterizing genetic influences on DNA methylation (DNAm) provides an opportunity to understand mechanisms underpinning gene regulation and disease. In the present study, we describe results of DNAm quantitative trait locus (mQTL) analyses on 32,851 participants, identifying genetic variants associated with DNAm at 420,509 DNAm sites in blood. We present a database of >270,000 independent mQTLs, of which 8.5% comprise long-range (trans) associations. Identified mQTL associations explain 15-17% of the additive genetic variance of DNAm. We show that the genetic architecture of DNAm levels is highly polygenic. Using shared genetic control between distal DNAm sites, we constructed networks, identifying 405 discrete genomic communities enriched for genomic annotations and complex traits. Shared genetic variants are associated with both DNAm levels and complex diseases, but only in a minority of cases do these associations reflect causal relationships from DNAm to trait or vice versa, indicating a more complex genotype-phenotype map than previously anticipated.Molecular Epidemiolog

A measurement of B(D+S → φl+ν) B(D+S → φπ+)

Using the CLEO II detector at CESR, we have measured the ratio of branching fractions B (D + S → φl + ν) B (D + S → φπ + ) = 0.54 ± 0.05 ± 0.04 . We use this measurement to obtain a model dependent estimate of B (D + S → φπ + )