Chord Measurements Research Articles

Influence of long-span bridge deformation on driving quality of high-speed trains

ABSTRACT Bridge time-varying deformation is the time-spatial dynamic deformation of a bridge excited by train motion, which serves as the direct alignment affecting a train’s dynamic response and usually moves ahead of the train. In this study, we investigated the influence of the bridge time-varying deformation on the vertical acceleration of a train with 16 cars on a long-span suspension bridge through the train-track-bridge coupled vibration analysis and chord measurements of dynamic spatial alignment. The analysis and measurements reveal the mechanism of the influence of different bridge positions on the car-body acceleration of different cars. Furthermore, we developed a simple method to identify the most unfavourable intersection position of multi-line driving based on the observed mechanism. In single-line operation, the maximum curvature of the main girder caused by bridge deformation with wavelengths above 200 m appears at the bridge tower and mid-span, while the maximum chord-measurement alignment with wavelengths below 200 m appears at the bridge tower, showing that the deformation at the tower area is more significant and that first car or sixteenth car will experience the maximum acceleration. For the multi-line operation, the curvature and chord measurements can be calculated by the superimposition of alignment with the wavelengths above and below 200 m, consecutively; hence, the most unfavourable intersection can be predicted according to the location and intersection of the maximum value. The intersection of two trains can increase the train’s centrifugal and vibration accelerations, causing the maximum acceleration to occur at the tower, where two trains meet at the most unfavourable one-fourth span of the bridge, which is verified by the train-track-bridge system.

Interactive effects of multiscale diversification practices on farmland bird stress.

Farmland diversification practices (i.e., methods used to produce food sustainably by enhancing biodiversity in cropping systems) are sometimes considered beneficial to both agriculture and biodiversity, but most studies of these practices rely on species richness, diversity, or abundance as a proxy for habitat quality. Biodiversity assessments may miss early clues that populations are imperiled when species presence does not imply persistence. Physiological stress indicators may help identify low-quality habitats before population declines occur. We explored how avian stress indicators respond to on-farm management practices and surrounding seminatural area (1-km radius) across 21 California strawberry farms. We examined whether commonly used biodiversity metrics correlate with stress responses in wild birds. We used ∼1000 blood and feather samples and body mass and wing chord measurements, mostly from passerines, to test the effects of diversification practices on four physiological stress indicators: heterophil to lymphocyte ratios (H:L), body condition, hematocrit values, and feather growth rates of individual birds. We then tested the relationship between physiological stress indicators and species richness, abundance, occurrence, and diversity derived from 285 bird point count surveys. After accounting for other biological drivers, landscape context mediated the effect of local farm management on H:L and body condition. Local diversification practices were associated with reduced individual stress in intensive agricultural landscapes but increased it in landscapes surrounded by relatively more seminatural area. Feathers grew more slowly in landscapes dominated by strawberry production, suggesting that nutritional condition was lower here than in landscapes with more crop types and seminatural areas. We found scant evidence that species richness, abundance, occurrence, or diversity metrics were correlated with the individual's physiological stress, suggesting that reliance on these metrics may obscure the impacts of management on species persistence. Our findings underscore the importance of considering landscape context when designing local management strategies to promote wildlife conservation.

Measurement Distortion Analysis of Repetitive and Isolated Track Geometry Irregularities

Track geometry measurements are essential for day-to-day activities of railway maintenance and play an important role in vehicle-track simulations. The generally applied forms of longitudinal level and alignment recordings do not reflect the real shape of the track. Both the versine measurement method and the band-pass filters according to European regulation cause significant amplitude modification and pattern change. In addition, the distortion behavior of repetitive and isolated defects is fundamentally different. In this contribution, simulated measurements of various reference shapes, which represent repetitive and isolated track deformations, were investigated. Comprehensive functions for amplitude change and for other distortion factors were developed with analytical and numerical methods. For chord measurements, rules were found for zero points and distortion-free ranges. Regarding the standardized filters, a significant amplitude reduction of isolated defects was observed in all wavelength ranges. Since derailment and track degradation depend not only on the amplitude of the defect, also the derivatives of the original and filtered forms of reference shapes were investigated and, as a new approach, the defect features called 'hypothetical additional force', 'speed of hypothetical wheel lift-off', 'hypothetical deterioration impulse' and 'hypothetical deterioration energy' were introduced.

Secular trends in cranial chord variables: a study of changes in sexual dimorphism of the North Indian population during 1954–2011

Background: Sex estimation of fragmentary remains is a critical problem which is further aggravated by the changing pattern of sexual dimorphism due to temporal/secular changes. Previously cranial chord variables were examined only to deduce cranial abnormalities and hominin evolution. In forensic anthropological literature to date, no studies have examined the importance of cranial chord variables in sex determination and neither have secular changes been reported in those measurements to date.Aim: The present study aims to examine the sexual dimorphism and temporal changes in chord measurements in the Indian population and to provide updated sex discriminant formulae.Subjects and methods: A total of 483 (contemporary: n = 158; sub-recent: n = 325) adult crania (18–70 years) from two temporally distinct North Indian populations were included in the study. Seven chord variables were measured and data were subjected to discriminant function analysis using SPSS 16.00.Results: Analysis of the data using the t-test demonstrated significant sexual and population variations over time. Univariate discriminant analysis revealed the glabella-bregma chord as the best variable in both populations (78.5 and 74.5% accuracy in the contemporary and sub-recent populations, respectively). Using multivariate analysis classification accuracy reached 86.1% in the contemporary sample.Conclusion: It is concluded that Indian crania are going through secular changes as the contemporary population has larger chord dimensions than their predecessors and chord variables can be applied for sex estimation in the Indian population.

Precise railway alignment measurements of the horizontal circular curves and the vertical parabolic curves using the chord method

The chord method is generally used for the horizontal and vertical versine measurements of rails in order to maintain their alignment. In this study, the horizontal versines of the left and right rails were precisely calculated, and the vertical versine functions were exactly derived. According to the inferences, the line charts used for determining the vertical versine were created to demonstrate the proportional relationship with the grade difference and the curve length. The equations for proximate vertical versine calculations were therefore derived. The asymmetrical chord measurements were introduced as well. The results indicated that the versine difference between the inner and outer rails should be considered when measuring the horizontal circular curve with a radius less than 300 m using a 10-m chord. According to the design criteria, a maximum vertical versine of 30 mm formed by the parabolic curves could be measured using a 10 -m chord, or a maximum versine of 7.5 mm could be measured using a 5 -m chord, which should be considered as the essential versines. The deviation tolerance should be based on these values for accurate rail inspections.

Two-dimensional particle shape analysis from chord measurements to increase accuracy of particle shape determination

Some in-process two-dimensional particle sizing methods can provide on-line information about the chord length distribution of a population of particles. The objective of this study is to use the chord measurement not only for the size determination but also for the determination of the particle shape. Main results are the non-dimensional aspect ratio or the roundness of the particle. The elongation values can be calculated by three non-dimensional parameters which are derived from the mean, mode or maximal chord length of the number and area based chord distributions. The application of these shape parameters is limited to narrow particle size and shape distributions. The application is demonstrated for coating of elliptical seed particles and spherical pellets (Cellets®1000). An optical probe system (IPP 70, Parsum GmbH, Germany) was used for the measurement of chord lengths during the coating processes. Results of an image analysis were in a good correlation with the results of the chord measurements. The advantage is the simultaneous use of the measured chord lengths for the characterization of the particle size and also the particle shape without any need for additional measurement equipment. Another advantage is the in-line determination of the particle shape without taking a powder sample.

Influence of atomic physics on EDGE2D-EIRENE simulations of JET divertor detachment with carbon and beryllium/tungsten plasma-facing components

The EDGE2D-EIRENE code is applied for simulation of divertor detachment during matched density ramp experiments in high triangularity, L-mode plasmas in both JET-Carbon (JET-C) and JET-ITER-Like Wall (JET-ILW). The code runs without drifts and includes either C or Be as impurity, but not W, assuming that the W targets have been coated with Be via main chamber migration. The simulations reproduce reasonably well the observed particle flux detachment as density is raised in both JET-C and JET-ILW experiments and can better match the experimental in-out divertor target power asymmetry if the heat flux entering the outer divertor is artificially set at around 2–3 times that entering the inner divertor. A careful comparison between different sets of atomic physics processes used in EIRENE shows that the detachment modelled by EDGE2D-EIRENE relies only on an increase of the particle sinks and not on a decrease of the ionization source. For the rollover and the beginning of the partially detached phase, the particle losses by perpendicular transport and the molecular activated recombination processes are mainly involved. For a deeper detachment with significant target ion flux reduction, volume recombination appears to be the main contributor. The elastic molecule-ion collisions are also important to provide good neutral confinement in the divertor and thus stabilize the simulations at low electron temperature (Te), when the sink terms are strong. Comparison between EDGE2D-EIRENE and SOLPS4.3 simulations of the density ramp in C shows similar detachment trends, but the importance of the elastic ion-molecule collisions is reduced in SOLPS4.3. Both codes suggest that any process capable of increasing the neutral confinement in the divertor should help to improve the modelling of the detachment. A further outcome of this work has been to demonstrate that key JET divertor diagnostic signals—Langmuir probe Te and bolometric tomographic reconstructions—are running beyond the limit of validity in high recycling and detached conditions and cannot be reliably used for code validation. The simulations do, however, reproduce the trend of the evolution of the line integrated bolometer chord measurements. The comparison between the code results and high-n Balmer line radiation intensity profiles confirms that a strong volume recombination is present during the experimental detachment and may play a role in this process, as suggested by the code.

Optimization of J-TEXT three-wave polarimeter-interferometer system

A laser-based three-wave polarimeter-interferometersystem (POLARIS) is operational on J-TEXT tokamak (R=1.05 m, a=0.27 m) tomeasure plasma electron density and Faraday rotation angle simultaneously.Vibration and collinearity are two key factors which affect the accuracy ofthe measurement. Vibration at the amplitude of even 1 μm is able toinduce almost 1° error (λ=432 μm) to the measurementthrough phase detection. And misalignment of collinearity can also causesystematic error to the measurement of Faraday angle due to density gradientand path length difference. Thus the systematic error from these two sourcesshould be eliminated to obtain accurate equilibrium and fluctuationinformation of the plasma. Some work has been done on optimizing vibrationand collinearity to achieve this goal. After optimization, POLARIS now hasachieved 12 chord measurements (spacing of 3 cm) with high temporal andphase resolution. Details of the optimization and results are described inthis study.

Testing subspecies hypothesis with molecular markers and morphometrics in the Pacific white tern complex

To test the validity of subspecies designations of the white tern, genetic and morphological data were used to assess differences among four putative Pacific subspecies Gygis alba candida, Gygis alba rothschildi, Gygis alba pacifica, and Gygis alba microrhyncha. The origin(s) of a recent colonization of Oahu was also examined using molecular data. Samples were collected from 209 birds, representing island groups of the North and South Pacific. Culmen length and depth, longest and shortest rectrix lengths, and wing chord measurements from an earlier dataset were compared. Mitochondrial DNA variation suggests that there are no phylogenetically distinct species within the Pacific Ocean. The genetic and morphological similarity of G. a. candida and G. a. rothschildi warrants merging them into one subspecies (G. a. candida). Gygis alba microrhyncha and G. a. pacifica are distinctly smaller and larger than the other two subspecies, respectively, but are not completely diagnosable across the morphological characters examined. Although the Pacific subspecies do not exhibit reciprocal monophyly, there is significant genetic differentiation among the two South Pacific groups, G. a. microrhyncha, G. a. pacifica, and all other Pacific subspecies. This differentiation warrants treating these two South Pacific groups as separate management units, but not species or subspecies. Finally, the recently established population of white terns on Oahu shared haplotypes with all subspecies, suggesting multiple origins from populations across the Pacific and confirming contemporary gene flow. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 586–595.

Allometric scaling of infraorbital surface topography in Homo

Infraorbital morphology is often included in phylogenetic and functional analyses of Homo. The inclusion of distinct infraorbital configurations, such as the “canine fossa” in Homo sapiens or the “inflated” maxilla in Neandertals, is generally based on either descriptive or qualitative assessments of this morphology, or simple linear chord and subtense measurements. However, the complex curvilinear surface of the infraorbital region has proven difficult to quantify through these traditional methods. In this study, we assess infraorbital shape and its potential allometric scaling in fossil Homo ( n = 18) and recent humans ( n = 110) with a geometric morphometric method well-suited for quantifying complex surface topographies. Our results indicate that important aspects of infraorbital shape are correlated with overall infraorbital size across Homo. Specifically, individuals with larger infraorbital areas tend to exhibit relatively flatter infraorbital surface topographies, taller and narrower infraorbital areas, sloped inferior orbital rims, anteroinferiorly oriented maxillary body facies, posteroinferiorly oriented maxillary processes of the zygomatic, and non-everted lateral nasal margins. In contrast, individuals with smaller infraorbital regions generally exhibit relatively depressed surface topographies, shorter and wider infraorbital areas, projecting inferior orbital rims, posteroinferiorly oriented maxillary body facies, anteroinferiorly oriented maxillary processes, and everted lateral nasal margins. These contrasts form a continuum and only appear dichotomized at the ends of the infraorbital size spectrum. In light of these results, we question the utility of incorporating traditionally polarized infraorbital morphologies in phylogenetic and functional analyses without due consideration of continuous infraorbital and facial size variation in Homo. We conclude that the essentially flat infraorbital surface topography of Neandertals is not unique and can be explained, in part, as a function of possessing large infraorbital regions, the ancestral condition for Homo. Furthermore, it appears likely that the diminutive infraorbital region of anatomically modern Homo sapiens is a primary derived trait, with related features such as depressed infraorbital surface topography expressed as correlated secondary characters.

Identifying artificially deformed crania

AbstractIn this paper we report on a new discriminant function for the identification of artificially deformed crania. Development of the function, based on a sample of deformed and undeformed crania from the Philippines, required visual classification of the sample into deformed and undeformed groups. Working from the observation that deformed crania display flattened frontal and occipital regions, the sample was seriated based on degree of flattening; classification was based on the results of this seriation. The discriminant function, calculated using curvature indices, required only six simple measurements: arc and chord measurements for the frontal (glabella to bregma), parietals (bregma to lambda) and occipital (lambda to opisthion). The function was designed to be conservative, in that a deformed cranium may be classified as undeformed, but the opposite should not occur. Our function classified the undeformed crania with 100% accuracy and deformed crania with 76.9% accuracy, for a total of 91.9% agreement with visual classification. In order to evaluate whether the function is applicable for samples from outside the Philippines, a double blind test was conducted with a large sample of deformed and undeformed crania from a broad geographical and temporal range. For this sample, the function agreed with visual classification in 89.7% of cases; 98.8% of undeformed crania were correctly classified, while deformed crania were identified with 73.7% accuracy. These results demonstrate the utility of the new discriminant function for the classification of artificially deformed crania from diverse contexts. Copyright © 2007 John Wiley & Sons, Ltd.

Five sensitivities of the coupled volume/double sloped system

Stop chord measurements taken in an existing coupled volume concert hall, established statistically-based formulas, ray-tracing-software simulations, and headphone listening perception/preference studies imply a fickle relationship between the coupled volume concert hall, the double-sloped sound decay, and the listener. The two halls examined in this study suggest five sensitivities of the system: (1) To produce a double sloped sound decay, the coupled volume must be exceedingly more reverberant than the main hall to which it is attached. (2) To produce a double sloped sound decay, the sonic aperture linking the coupled volume to the main hall must be exceedingly small. (3) Maintaining low levels of background noise—always essential when designing spaces for music listening—is especially important if the double sloped impulse response is to be perceived above the noise floor. (4) Listeners who sit near the apertures probably hear something different than those who sit nearer to the center of the hall. (5) It is unclear whether subjects taking a paired comparison test prefer a double sloped auralization to a classic Sabine auralization.

Particle and droplet size analysis from chord measurements using Bayes' theorem

A method of predicting sphere diameter distributions from chord size data is presented and evaluated. This is the probability apportioning method (PAM2) and is significantly improved on a previous presentation. It assumes that the particles or droplets are near spherical and cut randomly by a sensor. For an assumed particle diameter distribution, Bayes' theorem is used to calculate hit probabilities for each particle diameter. The diameter distribution is then recalculated and the process is repeated until there is no significant further change. Using numerical simulations, PAM2 is shown to be quite accurate and robust for a number of different types of size distribution.

Non-Spherical 2-Dimensional Particle Size Analysis from Chord Measurements using Bayes' Theorem

A method of deconvoluting 2-dimensional particle size distributions from chord size data is presented and evaluated. This is the Probability Apportioning Method (PAM3). It assumes that the particles (or droplets) can be represented by super quadrics and are cut randomly by a sensor to give a chord measurement. Starting from an assumed uniform particle distribution, Bayes' theorem is used to calculate hit probabilities for each particle type and the population is then recalculated. The process is then repeated until there is no significant further change in the calculated distribution. Using numerical simulations PAM3 is shown to be quite accurate and robust for a number of different types of particle shapes provided there is a sufficient number of accurate measurements.

SEXUAL DICHROMATISM IN THE PLUMAGE OF JUVENILE BROWN-HEADED COWBIRDS

Abstract We describe sexual dichromatism in the plumage of juvenile Brown-headed Cowbirds (Molothrus ater obscurus) collected in Ventura County, California in 1991. The dichromatism was based on two colorimetric features. The first was the contrast between the greater underwing coverts and the remiges, with males having darker coverts, and therefore greater contrast between their underwing coverts and remiges. The second was the color and extent of pale feather edges on the underside of the distal portion of the carpometacarpal joint, with males having wider, slightly darker feather edging. Five observers were used to test the reliability of these characters in a sample of museum wings from cowbirds of known sex. They were 88–94% accurate at determining the sex of 33 juvenile cowbirds (17 males, 16 females) using these two colorimetric characters. This technique was slightly more reliable than wing chord (84.8% accurate) and tarsometatarsus (also 84.8% accurate) measurements in differentiating the sex of ...

Particle and droplet size analysis from chord distributions

Two methods of estimating particle or droplet size distributions from chord measurements are presented and evaluated. The first is a probability apportioning method (PAM). This assumes that particles are cut randomly and calculates a diameter probability distribution from each chord size detected. The distribution is then accumulated over all chord measurements. PAM has proved to be a fairly robust method when the particle diameters are known. The second is a finite element method (FEM) that has been found to be more generally applicable where there is a wide range of unknown particle diameters. Both methods have been rigorously tested on sets of chord data developed from either the ideal probability functions, a distinct element simulation or true data from a chord measuring instrument (Par-Tec).

Post-treatment for phase detection probes in non uniform two-phase flows

The question of the demodulation of raw information delivered by phase detection probes is reconsidered. The standard procedure providing the size distribution from chord measurements is extended along various directions. For spherical inclusions, the presence of flow inhomogeneities is accounted for, both in the case of totally correlated or completely uncorrelated sizes and velocities. Also, the number density, its flux, as well as the mean interfacial area density, become available. Two-phase flow regions close to walls are also considered. It is shown that, using multiple point measurements, the number density flux can be reconstructed with acceptable accuracy. However, the number density and average inclusion velocity relative to centres seem to be out of reach when using only phase detection probes.

Cranial growth inHomo erectus: how credible are the Ngandong juveniles?

Confusion exists regarding the developmental ages of numerous Asian and southeast Asian Homo erectus fossils because of Weidenreich's contention that Pithecanthropus fused its sutures prematurely relative to H. sapiens. I reevaluate the cranial developmental ages of the Ngandong "juveniles" (2, 5, 8, 9) based on a series of indicators of youth (superstructure development, suture development/fusion, and cranial thickness) and cranial contours. The Ngandong juveniles are compared with H. sapiens adults (n = 281) and subadults (n = 81) and with Ngandong and other H. erectus adults (n = 20) and subadults (n = 4). Cranial contours are assessed using bivariate plots of arc vs. chord measurements. All indicators suggest that Ngandong 5 and 9 are adults, whereas Ngandong 8 is an older juvenile or young adult and Ngandong 2 is a juvenile with a developmental age range of greater than 6 and less than 11 years. In addition, adult cranial contours and the pattern of contour development are similar between Ngandong adults and other H. erectus adults. There is nothing in the cranial contour data to suggest that Ngandong is, despite a relatively large brain, transitional in vault shape between H. erectus and H. sapiens.

Artificial cranial deformation and fossil Australians revisited

Based on cranial characters shared byHomo erectusin Java andHomo sapiensin Australia, Australasia is widely considered the strongest case for a regional origin of modern humans. However, artificial vault deformation has been suggested to be the cause of “archaic” characters such as frontal recession in key fossil Australian crania. We use log–log plots of cranial arc versus chord measurements and we score nonmetric traits often thought to be associated with artificial deformation to make systematic comparisons across groups and deformation types to identify universal consequences of artificial deformation. Based on our large comparative sample (n=588) apparatus-deformed crania have flatter frontals and occipitals and usually more angulated parietals in the sagittal plane than undeformed crania, regardless of deformation type. Fossil Australian samples exhibit evidence of both undeformed and deformed individuals. The sample from Coobool Creek provides evidence that undeformed individuals had more rounded frontals than recent Australians. However, many individuals from Coobool Creek, Kow Swamp, and Nacurrie exhibit modification of one or more cranial contours. The Kow Swamp individuals in particular plot with deformed crania from all regions. In addition, the frequency of hyperostotic traits such as bregmatic eminence, metopic and sagittal keels inH. sapiensis influenced by both artificial deformation and pathological hypervascularity/hyperostosis. Thus it is unwise to use cranial contours and these nonmetric traits to infer genetic relatedness between Fossil Australians and IndonesianH. erectus.

Adult females and pubic bone growth.

Previous research (Tague [1994] Am. J. Phys. Anthropol. 95:27-40) has shown an age effect in pubic bone length among adult women. Tague found that in three prehistoric Native American skeletal samples, women aged 18-24 had a significantly shorter linea terminalis than did women aged 25 and older. The purpose of this research is to determine whether such a difference can be discerned in other female skeletal samples. Three female skeletal samples were used in this analysis: 75 African-American and 42 European-American females aged 18-39 from the Hamann-Todd Collection (collected between 1893 and 1938; Iscan, 1990) and 99 African-American females aged 18-39 from the Terry Collection (collected between 1914 and 1965; Cobb, 1933; Iscan, 1990). Several chord measurements of pubic bone length along the linea terminalis were analyzed by one-tailed t-tests of the separate samples subdivided into two age groups: 18-24 and 25-39 years. Of 15 comparisons between age groups, none differed significantly by age group within each sample. It is concluded that the observed significant difference in pubic bone length in the Native American female skeletal samples cannot be replicated in other samples and that there is no age effect on pubic bone length in the samples tested in this analysis. Tague's findings reflect either the occurrence of late menarche in prehistoric populations or differential survivorship.