Flow leaks renormalization

Flow leaks are small devices that generate a well-determined flow when subject to a pressure differential (feed pressure). Such devices are widely used in the industry for the easy generation of flows, which can be used for several applications. In order to be correctly included in a Quality Management System (QMS), they need to be calibrated against a reference flow. Such calibration depends on the feed pressure and on the fluid density through a complex relation which can be derived from the modified Darcy law, therefore results of a calibration performed in a given condition are not necessarily valid when the leak is used in different conditions (e.g. different atmospheric pressure, ambient temperature). In the present paper we will show how to obtain a correct renormalization of the calibration results, which, if applied in use, allows to compute precisely the actual flow rate generated by the leak. The renormalization is based on the modified Darcy law, and therefore requires the determination of the leak permeability. A mathematical description of the renormalization will be presented. Additionally, a method for the experimental determination of the permeability will be discussed The effect of the renormalization on the output of the leak will be demonstrated through a set of example cases, obtained in various environmental conditions within our laboratory. It will be shown that, first the calibration uncertainty can be reduced dramatically by applying the correct normalization, and second that the in-use uncertainty can be brought to be of the same order of magnitude as the calibration uncertaint

In-situ observations of an Antarctic polar stratospheric cloud: Similarities with Arctic observations

Geophysical Research Letters, Vol. 23, pp. 1913-1916, July 15, 1996

Observations of large reductions in NO/NOy ratio near the mid-latitude tropopause and the role of heterogeneous chemistry

Geophysical Research Letters, Vol. 23, No. 22, pp. 3223-3226, November 1, 1996.During the 1993 NASA Stratospheric Photochemistry, Aerosols and Dynamics Expedition (SPADE), anomalously low nitric oxide (NO) was found in a distinct sunlit layer located above the mid-latitude tropopause..

The Home Bias and Capital Income Flows between Countries and Regions

This paper documents a marked increase in international consumption risk sharing throughout the recent globalization period. Unlike earlier studies that have found it difficult to document a consistent effect of financial globalization on international consumption comovements, we make use of the information implicit in the relative levels of consumption and output to measure long-run risk sharing among OECD countries and US federal states.nWe derive our empirical setup from a deliberately simplistic model in which countries can trade perpetual claims to each other's output (Shiller securi-nties). Our framework allows us to distinguish between two channels of risk sharing: ex ante diversification that leads to income smoothing through cap-nital income flows and ex-post consumption smoothing through savings and dissavings. The model successfully replicates the patterns of income andnconsumption smoothing observed in both U.S. state-level and international data. The increase in international consumption risk sharing is closely associated with the decline in international portfolio home bias. While capital income flows remain relatively limited as a channel of risk sharing at businessncycle frequencies, we find that better international portfolio diversification has led to a considerable increase in capital income flows at medium and long horizons