Application Of Ultrasonic Technology To Improve The Reliability Of Magnetic-Drive Centrifugal Pumps

LectureIt is widely acknowledged that sealless magnetic drive pumps give total containment of the pumped process liquid, which in an industry where there are ever tightening environmental constraints on plant operation and increasing health and safety requirements, offers a real advantage of reliability and safety to users. However, as with any piece of process machinery, magnetic drive pumps are designed to operate within specific parameters and operation outside of these parameters can lead to reduced levels of reliability. Whilst traditional instrumentation (measurement of temperature or power) will assist in improving the reliability of the machine, these instruments are not monitoring the primary cause of the issue; instead they are monitoring the effect that the fault condition has on another part of the machine. By constantly monitoring the condition of the pumped liquid present in the internal flow regime of a magnetic-drive pump, it is possible to rapidly identify potential issues and react to them accordingly. Ultrasonic technology has been utilised to rapidly and accurately detect the presence of vapour in the liquid stream. The technology provides a precise and sensitive response to even the smallest change in phase, therefore improving the overall reliability of the machine. This paper presents an overview of the ultrasonic technology that has been utilised to monitor the condition of magnetic-drive centrifugal pumps, including highlights of extensive testing that has been carried out and some real world examples involving the application of this technology on volatile light hydrocarbon processes

Open Access Publishing for English Language Learners

Open access publishing for English language learners reinforces the notion that valuable perspectives can be shared with the academic community before attaining an idealized threshold of English language proficiency. This report offers a description of three case studies that illustrate how open access repositories can be used to provide publishing opportunities for English language learners and stimulate interest in academic writing. Historical background on open scholarship publishing is included, along with implications for policy. The report expands on a panel discussion presented by the authors at the 2023 EnglishUSA Professional Development Conference

Infiltration and short-term movement of nitrogen in a silt-loam soil typical of rice cultivation in Arkansas

Rice production in Arkansas is one of the top three crop commodities in terms of cash receipts. Researchers and farmers report that nitrogen (N) needs to be managed according to a variety of factors with two important ones being soil and fertilizer type. The objectives of this experiment were to determine: 1) the degree to which floodwater-incorporated N applied as urea or as ammonium sulfate infiltrates intact cores (7.2-cm dia., 10-cm depth) containing DeWitt siltloam soil, and 2) the distribution of N during 12 h of ponding. Inorganic-N concentrations were analyzed at 2-cm depth intervals in cores following removal of the flood. Nitrogen from applied fertilizer was recovered as ammonium. Ammonium sulfate-N remained in the top 4 cm of soil with concentrations of 375 µg N g-1 in the surface 2 cm and 300 µg N g-1 at the 2 - 4 cm depth after 12 hr of ponding. At all depth intervals below 4 cm, ammonium sulfate-N remained below 30 µg N g-1. In contrast, after 12 h of ponding, N in soil receiving urea was 105 µg N g-1 in the top 2 cm and 173 µg N g-1 at 2-4 cm. At 4-6, 6-8, and 8-10 cm, N was 109, 108, and 35 µg N g-1, respectively, after 12 h of ponding. These results demonstrate immediate and deeper movement of ammonium into silt loam soil receiving urea as compared to ammonium sulfate, demonstrating how the form of N in fertilizer affects its movement into the soil profile

Place-Based Industrial and Regional Strategy – Levelling the Playing Field

Over the past decade there has been renewed interest in the role of industrial strategy in enhancing innovation, productivity, and competitiveness within and across firms, sectors and regions with an eye to fostering more balanced regional economic growth. This special issue explores how policymakers could adopt place-based industrial policy measures to foster regional catch up and a more balanced and cohesive regional growth. In doing so, the papers are a mix of contributions that develop theory, provide evidence and highlight ‘state of the art’ or good practice that can inform a level playing field fostering regional industrial strategy

Asymmetric excitation of left- and right-tail extreme events probed using a Hawkes model: Application to financial returns

We construct a two-tailed peak-over-threshold Hawkes model that captures asymmetric self- and cross-excitation in and between left- and right-tail extreme values within a time series. We demonstrate its applicability by investigating extreme gains and losses within the daily log-returns of the S&P 500 equity index. We find that the arrivals of extreme losses and gains are described by a common conditional intensity to which losses contribute twice as much as gains. However, the contribution of the former decays almost five times more quickly than that of the latter. We attribute these asymmetries to the different reactions of market traders to extreme upward and downward movements of asset prices: an example of negativity bias, wherein trauma is more salient than euphoria.Comment: 11 pages. 7 figures and 5 table

Office-Based Deep Sedation for Pediatric Ophthalmologic Procedures Using a Sedation Service Model

Aims. (1) To assess the efficacy and safety of pediatric office-based sedation for ophthalmologic procedures using a pediatric sedation service model. (2) To assess the reduction in hospital charges of this model of care delivery compared to the operating room (OR) setting for similar procedures. Background. Sedation is used to facilitate pediatric procedures and to immobilize patients for imaging and examination. We believe that the pediatric sedation service model can be used to facilitate office-based deep sedation for brief ophthalmologic procedures and examinations. Methods. After IRB approval, all children who underwent office-based ophthalmologic procedures at our institution between January 1, 2000 and July 31, 2008 were identified using the sedation service database and the electronic health record. A comparison of hospital charges between similar procedures in the operating room was performed. Results. A total of 855 procedures were reviewed. Procedure completion rate was 100% (C.I. 99.62–100). There were no serious complications or unanticipated admissions. Our analysis showed a significant reduction in hospital charges (average of $1287 per patient) as a result of absent OR and recovery unit charges. Conclusions. Pediatric ophthalmologic minor procedures can be performed using a sedation service model with significant reductions in hospital charges

2T-POT Hawkes model for left- and right-tail conditional quantile forecasts of financial log-returns: out-of-sample comparison of conditional EVT models

Conditional extreme value theory (EVT) methods promise enhanced forecasting of the extreme tail events that often dominate systemic risk. We present an improved two-tailed peaks-over-threshold (2T-POT) Hawkes model that is adapted for conditional quantile forecasting in both the left and right tails of a univariate time series. This is applied to the daily log-returns of six large cap indices. We also take the unique step of fitting the model at multiple exceedance thresholds (from the 1.25% to 25.00% mirrored quantiles). Quantitatively similar asymmetries in Hawkes parameters are found across all six indices, adding further empirical support to a temporal leverage effect in financial price time series in which the impact of losses is not only larger but also more immediate. Out-of-sample backtests find that our 2T-POT Hawkes model is more reliably accurate than the GARCH-EVT model when forecasting (mirrored) value-at-risk and expected shortfall at the 5% coverage level and below. This suggests that asymmetric Hawkes-type arrival dynamics are a better approximation of the true data generating process for extreme daily log-returns than GARCH-type conditional volatility; our 2T-POT Hawkes model therefore presents a better performing alternative for financial risk modelling.Comment: Main paper: 25 pages, 7 figures, 6 tables. Supplementary material: 12 pages, 14 figure