Blip glitches in Advanced LIGO data Cabero, M; Lundgren, A; Nitz, A H ...
Classical and quantum gravity,
08/2019, Letnik:
36, Številka:
15
Journal Article
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Blip glitches are short noise transients present in data from ground-based gravitational-wave observatories. These glitches resemble the gravitational-wave signature of massive binary black hole ...mergers. Hence, the sensitivity of transient gravitational-wave searches to such high-mass systems and other potential short duration sources is degraded by the presence of blip glitches. The origin and rate of occurrence of this type of glitch have been largely unknown. In this paper we explore the population of blip glitches in Advanced LIGO during its first and second observing runs. On average, we find that Advanced LIGO data contains approximately two blip glitches per hour of data. We identify four subsets of blip glitches correlated with detector auxiliary or environmental sensor channels, however the physical causes of the majority of blips remain unclear.
The percent composition of blends of biodiesel and conventional diesel from a variety of retail sources were modeled and predicted using partial least squares (PLS) analysis applied to gas ...chromatography–total-ion-current mass spectrometry (GC–TIC), gas chromatography–mass spectrometry (GC–MS), comprehensive two-dimensional gas chromatography–total-ion-current mass spectrometry (GCxGC–TIC) and comprehensive two-dimensional gas chromatography–mass spectrometry (GCxGC–MS) separations of the blends. In all four cases, the PLS predictions for a test set of chromatograms were plotted versus the actual blend percent composition. The GC–TIC plot produced a best-fit line with slope=0.773 and y-intercept=2.89, and the average percent error of prediction was 12.0%. The GC–MS plot produced a best-fit line with slope=0.864 and y-intercept=1.72, and the average percent error of prediction was improved to 6.89%. The GCxGC–TIC plot produced a best-fit line with slope=0.983 and y-intercept=0.680, and the average percent error was slightly improved to 6.16%. The GCxGC–MS plot produced a best-fit line with slope=0.980 and y-intercept=0.620, and the average percent error was 6.12%. The GCxGC models performed best presumably due to the multidimensional advantage of higher dimensional instrumentation providing more chemical selectivity. All the PLS models used 3 latent variables. The chemical components that differentiate the blend percent compositions are reported.
► Biodiesels from three different feedstocks were blended with conventional diesels. ► The blends were separated by GC–qMS with a polar column as well as a nonpolar column. ► Feature selection, ...scaling, PCA, HCA, and KNN were used to determine the feedstock. ► Blend percent composition was determined using a PLS model built for the feedstock.
The two main goals of the analytical method described herein were to (1) use principal component analysis (PCA), hierarchical clustering (HCA) and K-nearest neighbors (KNN) to determine the feedstock source of blends of biodiesel and conventional diesel (feedstocks were two sources of soy, two strains of jatropha, and a local feedstock) and (2) use a partial least squares (PLS) model built specifically for each feedstock to determine the percent composition of the blend. The chemometric models were built using training sets composed of total ion current chromatograms from gas chromatography–quadrupole mass spectrometry (GC–qMS) using a polar column. The models were used to semi-automatically determine feedstock and blend percent composition of independent test set samples. The PLS predictions for jatropha blends had RMSEC=0.6, RMSECV=1.2, and RMSEP=1.4. The PLS predictions for soy blends had RMSEC=0.5, RMSECV=0.8, and RMSEP=1.2. The average relative error in predicted test set sample compositions was 5% for jatropha blends and 4% for soy blends.
We present a laboratory experiment for an advanced analytical chemistry course where we first focus on the chemometric technique partial least-squares (PLS) analysis applied to one-dimensional (1D) ...total-ion-current gas chromatography−mass spectrometry (GC-TIC) separations of biodiesel blends. Then, we focus on n-way PLS (n-PLS) applied to two-dimensional (2D) gas chromatography−mass spectrometry (GC−MS) separations of biodiesel blends. The purpose of the experiment is to determine the percent composition, by volume, of biodiesel in an unknown blend of biodiesel and conventional diesel. A secondary goal is to compare the prediction results of the PLS model to the n-PLS model to see if there is an advantage to analyzing multiple dimensions. The instructor initially creates a PLS model and an n-PLS model using separations of standard biodiesel blends where the percent compositions are known and vary from 0% to 20%. Then, the student collects the GC-TIC and GC−MS chromatograms of an unknown biodiesel blend to regress onto PLS and n-PLS models and discover the percent composition of the unknown sample.
The sensitivity of the Advanced LIGO detectors to gravitational waves can be affected by environmental disturbances external to the detectors themselves. Since the transition from the former initial ...LIGO phase, many improvements have been made to the equipment and techniques used to investigate these environmental effects. These methods have aided in tracking down and mitigating noise sources throughout the first three observing runs of the advanced detector era, keeping the ambient contribution of environmental noise below the background noise levels of the detectors. In this paper we describe the methods used and how they have led to the mitigation of noise sources, the role that environmental monitoring has played in the validation of gravitational wave events, and plans for future observing runs.
Primary objective : In 1989, a new therapy to reduce intracranial pressure in severely head-injured patients was introduced in Lund. The new treatment reduced mortality significantly. The present ...study describes the quality of life for the survivors Methods and procedures : The study includes 53 patients treated during 1989?1994, according to a new treatment protocol for increased intracranial pressure (?Lund concept' group). During 1982?1986, 38 patients were managed according to a protocol including high dose thiopentone (?Thiopentone' group). The two groups are compared regarding neurophysical and psychiatric symptoms as well as aspects regarding the patient's role, performance, interpersonal relationship, frictions, feelings and satisfaction in work, areas of social and leisure activities, and extended family. Results : Mortality was reduced from 47% to 8%, but the number of patients with a persistent vegetative state and/or remaining severe disability did not increase. However, the number of patients with persisting emotional and intellectual deficits increased significantly. Conclusion : The new treatment regime has dramatically increased the number of survivors after severe head trauma. Although most patients have a favourable outcome, there are more patients with remaining sequelae and disabilities, and the demand for qualified rehabilitation has increased.
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