Risk Analysis of Natural Gas Distribution Pipelines with Respect to Third Party Damage

The objective of this study is to develop a quantitative method of evaluating the risk of third party damage (TPD) on natural gas distribution pipelines using available industry data and practical engineering experience. A risk model for TPD of gas distribution pipelines is developed to allow for a more robust decision making process and better prioritization of the allocation of resources for operators of natural gas distribution pipelines. The model consists of likelihood and consequence classification procedures to estimate the severity of TPD events within an area. The TPD model consists of a fault tree (FTA) model to estimate the probability of hit of a given distribution pipeline by third party excavation activities. The distribution FTA model is developed using TPD and locate records from 2014-2016 and survey data from transmission FTA models. This model is then validated by comparing the predicted and actual 2017 damage records in three municipalities in southwestern Ontario with populations varying from 200,000 to 350,000. Based on a historical analysis of distribution pipeline TPD consequence, a procedure is developed to classify the consequence of a TPD event within a given area. Methods of collecting and classifying data from sources available to distribution companies are used to allow this procedure to be implemented straightforwardly in an industry setting. In a case study a compromise solution method of evaluation is used to identify areas where focusing damage prevention resource would be most effective

High-growth firms: introduction to the special section

High-growth firms (HGFs) have attracted considerable attention recently, as academics and policymakers have increasingly recognized the highly skewed nature of many metrics of firm performance. A small number of HGFs drives a disproportionately large amount of job creation, while the average firm has a limited impact on the economy. This article explores the reasons for this increased interest, summarizes the existing literature, and highlights the methodological considerations that constrain and bias research. This special section draws attention to the importance of HGFs for future industrial performance, explores their unusual growth trajectories and strategies, and highlights the lack of persistence of high growth. Consequently, while HGFs are important for understanding the economy and developing public policy, they are unlikely to be useful vehicles for public policy given the difficulties involved in predicting which firms will grow, the lack of persistence in high growth levels, and the complex and often indirect relationship between firm capability, high growth, and macro-economic performance

The Role of Scanning Electron Microscopy in Periodontal Research

During recent years a great amount of research has led to a better understanding of the etiology, pathogenesis and pattern of progression of periodontal diseases. Scanning electron microscopy (SEM) has contributed to this improvement, mainly with respect to histology of periodontal tissues, the description of the morphology and distribution of bacteria on the exposed root surface, analysis of the host-parasite interactions on the gingival pocket wall, and morphological evaluation of root treatment. This review deals with all these topics. Unusual types of SEM research are also described and discussed. Uncommon sample preparation techniques for SEM in periodontal research are described. SEM in periodontal research should be of great application in the near future. Cathodoluminescence, backscattered emission and immunolabelling techniques will be formidable tools in this field of dentistry

Low frequency geomagnetic field fluctuations at cap and low latitude during October 29-31, 2003

On October-November 2003 complex interplanetary structures, originated by a series of solar eruptions, hit the Earth, triggering violent Sun-Earth connection events. In this paper we analyze the low frequency geomagnetic field fluctuations detected on the ground during Oct. 29-31, 2003, a time period characterized by extremely high solar wind speed values and by out-of-ecliptic interplanetary magnetic field orientation for intervals of several hours. We analyze geomagnetic field measurements at four high latitude stations located in the polar cap, three in the southern and one in the northern hemisphere. From a comparison with simultaneous measurements at low latitude, we address the question of the global character of the observed phenomena. The results show, for selected time intervals, the occurrence of simultaneous fluctuations at all the stations, with high coherence even between high and low latitude; it is interesting that these fluctuations are detected during open magnetospheric conditions, when the high latitude stations are situated well within the polar cap, i.e. far from closed field lines

Progress in Atomic Fountains at LNE-SYRTE

We give an overview of the work done with the Laboratoire National de M\'etrologie et d'Essais-Syst\`emes de R\'ef\'erence Temps-Espace (LNE-SYRTE) fountain ensemble during the last five years. After a description of the clock ensemble, comprising three fountains, FO1, FO2, and FOM, and the newest developments, we review recent studies of several systematic frequency shifts. This includes the distributed cavity phase shift, which we evaluate for the FO1 and FOM fountains, applying the techniques of our recent work on FO2. We also report calculations of the microwave lensing frequency shift for the three fountains, review the status of the blackbody radiation shift, and summarize recent experimental work to control microwave leakage and spurious phase perturbations. We give current accuracy budgets. We also describe several applications in time and frequency metrology: fountain comparisons, calibrations of the international atomic time, secondary representation of the SI second based on the 87Rb hyperfine frequency, absolute measurements of optical frequencies, tests of the T2L2 satellite laser link, and review fundamental physics applications of the LNE-SYRTE fountain ensemble. Finally, we give a summary of the tests of the PHARAO cold atom space clock performed using the FOM transportable fountain.Comment: 19 pages, 12 figures, 5 tables, 126 reference

The Earth’s passage of coronal mass ejecta on October 29-31, 2003: ULF geomagnetic field fluttuations at very high latitude

We study ULF geomagnetic field fluctuations detected on October 29-31, 2003, when the Earth’s arrival of solar wind CMEs produced major geomagnetic storms; these solar wind structures are characterized by extremely high plasma speed and long-duration intervals with northward interplanetary magnetic field. The analyzed geomagnetic field data are from four high latitude stations (three in Antarctica), located deep in the polar cap. The analysis is extended also to low latitude European stations, in order to discriminate between local and global magnetospheric phenomena

Low frequency geomagnetic field fluctuations in Antarctica: comparison between two polar cap stations

We present a statistical analysis of low frequency (~0.5-5 mHz, periods ~3-30 min) geomagnetic field fluctuations at the Antarctic stations Mario Zucchelli Station (TNB, formerly Terra Nova Bay) and Scott Base (SBA), which are located at the same geomagnetic latitude but with 1-hr difference in MLT (Table 1). The two stations are usually in the polar cap, at the footprint of open geomagnetic field lines, but around local geomagnetic noon they approach the polar cusp. This study focuses on the coherence and phase difference between the fluctuations at the two stations. The analysis is based on 1-min values of the horizontal H component measured during the entire years 2001-2002. The coherence and phase difference have been computed for each 2-hours interval with a step-size of 1 hour. Station TNB is run by INGV; data from SBA are provided by INTERMAGNET CD-ROMs. Interplanetary magnetic field (IMF) and solar wind (SW) data from ACE spacecraft have been downloaded from OMNI database. Interplanetary data have been delayed by 1 hour to take into account the average SW transit time from ACE to Earth