Determination Of Relative Changes Research Articles

Features of vibration-based damage detection in stepped shafts of steam turbines

The vibration-based damage detection has practically no alternative as applied to the rotating shafts of steam turbines during operation. However, taking into account the heavy operating conditions of turbines and the complex shape of turbines shaft, the choice of most effective method of vibration diagnostics is not an easy problem. To solve this problem, a relatively simple method of comparative evaluation of the effectiveness of vibration diagnostics of damage as applied to the stepped rotors and shafting of steam turbine was developed. The method is based on the determination of relative change of shaft's compliance caused by a crack with the use of linear fracture mechanics. As an example there was performed the comparative analysis of efficiency of vibration diagnostics, namely the change of natural bending, longitudinal or torsional frequency of vibration and the nonlinear effects, to detect transverse or longitudinal crack in rotors and shafting of steam turbine K-215-130.

Giant Pressure-Induced Enhancement of Seebeck Coefficient and Thermoelectric Efficiency in SnTe.

The thermoelectric properties of polycrystalline SnTe have been measured up to 4.5 GPa at 330 K. SnTe shows an enormous enhancement in Seebeck coefficient, greater than 200 % after 3 GPa, which correlates to a known pressure-induced structural phase transition that is observed through simultaneous in situ X-ray diffraction measurement. Electrical resistance and relative changes to the thermal conductivity were also measured, enabling the determination of relative changes in the dimensionless figure of merit (ZT), which increases dramatically after 3 GPa, reaching 350 % of the lowest pressure ZT value. The results demonstrate a fundamental relationship between structure and thermoelectric behaviours and suggest that pressure is an effective tool to control them.

Transcriptome-Based Identification of the Optimal Reference CHO Genes for Normalisation of qPCR Data.

Real-time quantitative PCR (qPCR) is the standard method for determination of relative changes in mRNA transcript abundance. Analytical accuracy, precision and reliability are critically dependent on the selection of internal control reference genes. In this study, the authors have identified optimal reference genes that can be utilised universally for qPCR analysis of CHO cell mRNAs. Initially, transcriptomic datasets were analysed to identify eight endogenous genes that exhibited high expression stability across four distinct CHO cell lines sampled in different culture phases. The relative transcript abundance of each gene in 20 diverse, commonly applied experimental conditions was then determined by qPCR analysis. Utilizing GeNorm, BestKeeper and NormFinder algorithms, the authors identified four mRNAs (Gnb1, Fkbp1a, Tmed2 and Mmadhc) that exhibited a highly stable level of expression across all conditions, validating their utility as universally applicable reference genes. Whilst any combination of only two genes can be generally used for normalisation of qPCR data, the authors show that specific combinations of reference genes are particularly suited to discrete experimental conditions. In summary, the authors report the identification of fully validated universal reference genes, optimised primer sequences robust to genomic mutations and simple reference gene pair selection guidelines that enable streamlined qPCR analyses of mRNA abundance in CHO cells with maximum accuracy and precision.

Validation of kinematically simulated pattern HR-EBSD for measuring absolute strains and lattice tetragonality

Cross correlation techniques applied to EBSD patterns have led to what has been termed “high-resolution EBSD” (HR-EBSD). The technique yields higher accuracy orientation and strain data which is obtained by comparing a given EBSD pattern with either a real or a simulated reference pattern. Real reference patterns are often taken from a “central” position in a given grain, where it is hoped that the material is “strain-free”, and they enable the determination of relative changes in orientation and strain from that present in the lattice at the reference position. Simulated patterns, on the other hand, enable comparison of the sample lattice with that of a perfect lattice, resulting in a measure of absolute strain and orientation. However, the simulated pattern method has several drawbacks, including the need to accurately specify microscope geometry, the lower fidelity/detail of simulated patterns compared with real patterns, and the potential for microscope-specific bias in the measured patterns (such as due to optical distortion).These drawbacks have led to much debate about the utility of the cross-correlation technique using simulated patterns. This paper is the first to assess the accuracy of the simulated pattern method relative to the real pattern approach in a setting where accuracy can be reasonably determined, thus providing a fair assessment of the potential of the simulated pattern technique.Based upon recent developments towards a standard material for assessing strain mapping techniques, this paper assesses the overall accuracy of the simulated pattern technique. Mismatch strains are calculated using both the real and simulated pattern techniques for a SiGe film deposited on a Si substrate. While the simulated pattern technique is not as accurate or precise as the real pattern technique for providing relative strains, it provides an estimate of absolute strain that is not available via the real pattern approach.

Monitoring protein expression in whole-cell extracts by targeted label- and standard-free LC-MS/MS

Targeted quantification of proteins is a daily task in biological research but often relies on techniques such as western blotting that are only barely quantitative. Here we present a broadly applicable workflow for protein quantification from unpurified whole-cell extracts that can be completed in less than 3 d. Without prefractionation or affinity enrichment, a whole-cell extract is trypsin-digested in an acetonitrile-containing ammonium carbonate buffer and high-molecular-weight compounds are removed by filtration. A normalization strategy, which involves endogenous reference proteins, facilitates the determination of relative changes in protein expression without requiring isotope labeling or standard addition. On a triple-quadrupole mass spectrometer, we demonstrate standard-free quantification of yeast proteins present over five orders of magnitude and present at ≥500 copies per cell. Liquid chromatography/multiple reaction monitoring (LC-MRM)-based proteomics is therefore a next-generation alternative to western blotting, as it allows simultaneous and reliable quantification of multiple endogenous proteins without the need for enrichment, isotope labeling or use of antibodies.

On the use of ratio standard curves to accurately quantitate relative changes in protein levels by Western blot

Relative changes in the expression of a specific protein are commonly measured on western blots by forming the ratio of the densitometric values of bands containing the protein between control and experimental samples. It is generally assumed that this analysis provides an accurate determination of relative changes in a specific protein expression if there is a linear relation between increasing amounts of that protein, as represented by bands on a western blot or a gel, and the densitometric measurements of these bands. In this study, we provide direct evidence that this assumption is invalid because even in the presence of a linear relation, densitometric ratios differ substantially from know actual ratios of protein amounts. We present also the mathematical basis for this bias, and demonstrate that it can be circumvented by using a “ratio standard curve”. Alternatively, the use of purified protein standards to plot a standard densitometry curve can solve this problem, but a survey of the literature shows that most investigators who use western blots to quantify relative changes in protein expression samples do not have standards for the specific proteins that they are investigating.

Liquidity Across Developed and Emerging Markets

This paper analyzes market-wide liquidity using weekly data from 1990 to 2002 for a sample of 18 developed and emerging markets. The results suggest that market-wide liquidity is cross-sectionally determined by several country level variables: market returns and return volatilities, interest rates, and equity and bond portfolio country flows. Furthermore, there is evidence that the global components of these country-level variables are at least as important in explaining liquidity as country-specific information. Hence, the results support the notion of a global liquidity factor. A dynamic analysis of liquidity further confirms these variables as determinants of relative changes in liquidity. While common and country-specific factors help explain liquidity across countries and time, the pairwise correlation of changes in liquidity is low. The results from using extreme value theory to investigate whether shocks to liquidity are more strongly correlated during extreme market conditions offer no evidence of contagion.

Studies into the Internal Structure of Gibbsite Agglomerates

AbstractThis paper outlines techniques that have been developed or adapted to characterise the internal structure of gibbsite agglomerates and their application to selected laboratory gibbsite sample. The specific structural properties investigated include the quantification of gibbsite voidage (Floc Density Analyser), determination of relative changes in gibbsite crystal orientation (Raman spectroscopy and electron backscattered diffraction) and location of the cement binding agglomerated gibbsite particles (Raman spectroscopy, charge contrast and orientation contrast imaging). This paper also describes the use of Kikuchi patterns for investigating crystal orientation at a point and as a tool to assess if a particle is a single crystal or an agglomerate or a multi‐fold twin.

Global tropospheric and total ozone monitoring with a double-etalon Fabry–Perot interferometer II Feasibility analysis

The feasibility of observing global tropospheric and total ozone (O(3)) fields with a double-etalon Fabry-Perot interferometer (FPI) has been assessed. The FPI provides high spectral resolution and high-throughput capabilities that enable observation in pressure-broadened wings of strong O(3) lines while minimizing the impact of undesirable signal contributions (i.e., from the terrestrial surface and interfering species). A retrieval technique has been implemented and is demonstrated for a tropical atmosphere possessing enhanced tropospheric ozone amounts. An error analysis assessing the impact on retrieved O(3) amounts from the most significant uncertainties associated with this particular measurement has been performed, and findings for a tropical atmosphere are presented. Results show the proposed instrumentation to enable a good measurement of absolute ozone amounts and an even better determination of relative changes.

Electro-Optic Investigation of Oxide Suspensions: Scaling of the Electro-Optic Effects by Field Intensity

A method of treatment of electro-optic data, based on fitting of the field intensity dependencies of the effects by scaling of the field intensity, is proposed. The method permits the determination of relative changes in particle electric polarizability and its relaxation frequency for optically complicated dispersions (particles of large dimensions, of high refractive index, of low optical anisotropy, of concentrations involving multiple scattering, etc.).

A 35Cl NQR study of intra- and inter-molecular effects in acid salts of trichloroacetic acid

Cl NQR frequencies for 2:2 salts of trichloroacetic acid (TCA) with 4-methylpyridine- N-oxide and 4-methylquinoline- N-oxide were measured at 77 K. Comparison of Cl frequencies for 2:1 and 2:2 salts shows that the crystal field makes a small contribution to the frequency shifts (FS) produced by salt formation. Analysis of the spectra of 2:1 salts shows the quenching of the Sternheimer factor. The characteristics NQR spectrum of TCA is the result of differences in intramolecular interactions. It is shown that the existence of hydrogen bonds (HB) in pure TCA allows only the determination of relative changes in the HB network. From the analysis of the crystal field contribution to the FS in salts and addition complexes it is found that the inductive effect determines the FS in the TCA salts while in the addition complexes solid state effects are dominant.

A differential ionization chamber for the determination of small differences in decay rates of beta emitters

A differential ionization chamber for measurements of small changes in the rate of decay of pure beta emitters has been constructed. The characteristics of the chamber were studied for various experimental conditions. The apparatus can be used for the determination of relative changes in the radioactive decay constant Δγ/γ in the order of 10 −4 − 10 −5, which can be caused by different chemical states of the beta emitter. The methods used for checking the operation of the apparatus are illustrated.

The 6300 Å O 1 D airglow and dissociative recombination

Measurements of night-time 6300 Å airglow intensities at the Arecibo Observatory have been compared with dissociative recombination calculations based on electron densities derived from simultaneous incoherent backscatter measurements. The agreement indicates that the nightglow can be fully accounted for by dissociative recombination. Thecomparisons are examined to determine the importance of quenching, heavy ions, ionization above the F-layer peak, and the temperature parameter of the model atmosphere. Comparable fits between the observed and calculated intensities are found for several available model atmos- pheres (e.g. CIRA, Jacchia). The least-squares fitting process, used to make the comparisons, produces comparable fits over a wide range of combinations of neutral densities and of reaction constants. Yet, the fitting places constraints upon the possible combinations: these constraints indicate that the latest laboratory chemical constants and densities extrapolated to a base altitude are mutually consistent. However, by imposing an additional constraint, an aero- nomically derived preference is given for about one O( 1 D ) per combination. A preference is also given for the lower base densities of O 2 derived from rockets rather than from models. Altitude profiles for the 6300 Å and 5577 Å emissions are deduced. In the early evening, there are no large discrepancies in the fits that might indicate an effect from elicited states of O +, vibrational excitation of O 2, or both. The technique of comparing observed and cal- culated 6300 Å intensities has considerable potential as an aeronomical tool for examination of other possible sources of emission and for determination of relative changes in the neutral atmosphere.

Determination of relative change in percentage modulation in received backscattered light signal

Determination of relative change in percentage modulation in received backscattered light signal

On the manifestation of the 11-yr cycle of solar activity in the brightness of the nightglow

Measurements of night-time 6300 Å airglow intensities at the Arecibo Observatory have been compared with dissociative recombination calculations based on electron densities derived from simultaneous incoherent backscatter measurements. The agreement indicates that the nightglow can be fully accounted for by dissociative recombination. Thecomparisons are examined to determine the importance of quenching, heavy ions, ionization above the F-layer peak, and the temperature parameter of the model atmosphere. Comparable fits between the observed and calculated intensities are found for several available model atmos- pheres (e.g. CIRA, Jacchia). The least-squares fitting process, used to make the comparisons, produces comparable fits over a wide range of combinations of neutral densities and of reaction constants. Yet, the fitting places constraints upon the possible combinations: these constraints indicate that the latest laboratory chemical constants and densities extrapolated to a base altitude are mutually consistent. However, by imposing an additional constraint, an aero- nomically derived preference is given for about one O(1D) per combination. A preference is also given for the lower base densities of O2 derived from rockets rather than from models. Altitude profiles for the 6300 Å and 5577 Å emissions are deduced. In the early evening, there are no large discrepancies in the fits that might indicate an effect from elicited states of O+, vibrational excitation of O2, or both. The technique of comparing observed and cal- culated 6300 Å intensities has considerable potential as an aeronomical tool for examination of other possible sources of emission and for determination of relative changes in the neutral atmosphere.

Determination of relative changes in cardiac output from noncalibrated earpiece dye-dilution curves.

Many investigations require information on percentage changes in cardiac output rather than absolute values. This study investigates a simple method for measuring such relative changes, using noncalibrated earpiece dye-dilution curves. The basic principle involved is that, in an ideal system, the areas beneath successive dilution curves produced by equal injections of indicator are inversely proportional to the cardiac outputs. Applied to the earpiece dye-dilution curves, the restrictive assumptions relate mainly to linearity of response to blood concentration of dye and to the constancy of the blood volume of the ear. The method has been tested by recording simultaneous earpiece and arterial cuvette dye curves produced by injections of Coomassie Blue during changes in posture, exercise, and intravenous administration of vasoactive drugs. The relative changes in cardiac output predicted from the earpiece curves compared well with those from the arterial cuvette.