Locating leaks in underground water pipes using the complex cepstrum

It is possible to detect the presence of leaks in underground water pipes by measuring, at remote locations such as hydrants, the noise or vibration caused by the leak. The time delay of the leak noise reaching the different sensors can be computed using the cross correlation, and with knowledge of the wavespeed in the pipe, the location of the leak may be pinpointed. This paper presents a new technique for leak detection which employs the cepstrum, rather than the cross correlation, for estimation of the delay time. The delay time manifests as a series of peaks in the cepstrum, rather than a single peak in the correlation, allowing a more robust estimate. A number of cepstrum formulations are presented which are derived from correlation estimators, and it is found that the time delay information is actually contained in the phase component of the cross spectrum. Based on this, a phase cepstrum estimator is developed

Groundwater resources in Lee and Whiteside Counties

Enumeration continues through succeeding title

Groundwater resources in Lee and Whiteside Counties

Enumeration continues through succeeding title

Public ground-water supplies in Illinois

Enumeration continues from preceding title.Bulletin No. 40 is published to fill the need for revising and supplementing the contents of Bulletin No. 21 and Supplements I and II, published in 1925, 1938 and 1940 respectively. It is intended not only to include in this Bulletin all of the basic data which were written into Bulletin No. 21 and Supplements I and II but to make Bulletin No. 40 more complete. This is possible because prior to the time of publication of the original Bulletin No. 21 the public-was not aware of the need for accurate records of their water resources. In many cases, no records were kept of water levels and other important well data. At that time a public well could be constructed without notice to the State Department of Public Health. Notice was later made compulsory by law. Possibly ten or fifteen public well supplies were not included in Bulletin No. 21 because their existence was not known to the Water Survey staff

PCB and PBDE levels in southern and northern resident killer whales: update on contaminant levels and related health effects

Salish Sea’s killer whale populations are among the most contaminated marine mammals in the world and face risks related to the effects of polychlorinated biphenyls (PCBs) and related contaminants such as polybrominated diphenylethers (PBDEs). While PCBs have long been banned, they continue to present toxic risks to marine mammals, along with a number of other, emerging persistent, bioaccumulative and toxic (PBT) contaminants. Since PBTs have been identified as a threat to the recovery of resident killer whale populations under the auspices of the US Endangered Species Act and the Canadian Species at Risk Act (SARA), documenting the presence, trends and health effects of emerging PBT contaminants represents an important line of research. In the summer of 2016 and 2017, we collected blubber biopsies from 10 southern resident and nine northern resident killer whales. PCB and PBDE analyses were conducted using high resolution gas chromatography/high resolution mass spectrometry. Given the likelihood of significant temporal changes in the concentrations of these contaminants, this study will provide updated contaminant concentration data and strengthen our ability to prioritize contaminants of concern in resident killer whales. In addition, stable isotope and fatty acid analyses will provide important information on diet and nutritional status. Together with analyses of the expression of essential genes involved in immune response, hormone regulation and lipid metabolism, this study provides new essential information on the health status of resident killer whales as it relates to contaminant exposure and will help inform the development and application of recovery action plans

Trends in residential water use

Includes bibliographical references (p. 22).Enumeration continues through succeeding title

Trends in residential water use

Includes bibliographical references (p. 22).Enumeration continues through succeeding title

Correction to the Moliere's formula for multiple scattering

The quasiclassical correction to the Moliere's formula for multiple scattering is derived. The consideration is based on the scattering amplitude, obtained with the first quasiclassical correction taken into account for arbitrary localized but not spherically symmetric potential. Unlike the leading term, the correction to the Moliere's formula contains the target density $n$ and thickness $L$ not only in the combination $nL$ (areal density). Therefore, this correction can be reffered to as the bulk density correction. It turns out that the bulk density correction is small even for high density. This result explains the wide region of applicability of the Moliere's formula.Comment: 6 pages, RevTe

Graduate Recital: Judith Ross, Flute; Valerie Cribbs, Harp; Marcia Hishman, Piano; Martin Hanson, Cello; Lawrence Spence, Viola; October 27, 1975

Hayden AuditoriumMonday EveningOctober 27, 19758:15 p.m