Establishing a Detection Threshold for Acoustic-Based External Leak Detection Systems

2020 ◽  
Author(s):  
Mathew Bussière ◽  
Mark Stephens ◽  
Marzie Derakhshesh ◽  
Yue Cheng ◽  
Lorne Daniels
Keyword(s):  
Sensitivity Analysis ◽  
Detection Threshold ◽  
Leak Detection ◽  
Detection Sensitivity ◽  
Sensitivity Threshold ◽  
Detection Systems ◽  
Threshold Measure ◽  
Full Scale Tests ◽  
Parameter Values ◽  
Very High

Abstract A better understanding of the sensitivity threshold of external leak detection systems can assist pipeline operators in predicting detection performance for a range of possible leak scenarios, thereby helping them to make more informed decisions regarding procurement and deployment of such systems. The analysis approach described herein was developed to characterize the leak detection sensitivity of select fiber optic cable-based systems that employ Distributed Acoustic Sensing (DAS). The detection sensitivity analysis consisted of two steps. The first step involved identifying a suitable release parameter capable of providing a defensible basis for defining detection sensitivity; the second step involved the application of logistic regression analysis to characterize detection sensitivity as a function of the chosen release parameter. The detection sensitivity analysis described herein provides a means by which to quantitatively determine the leak detection sensitivity threshold for each technology and sensor deployment position evaluated in a set of full-scale tests. The chosen sensitivity threshold measure was the release parameter value associated with release events having a 90% probability of being detected. Thresholds associated with a higher probability level of 95% were also established for comparison purposes. The calculated sensitivity thresholds can be interpreted to mean that release events associated with release parameter values above the sensitivity threshold have a very high likelihood (either 90 or 95%) of being detected.

Effects of Data Preparation on Leak Sensitivity Analysis

2014 ◽  
Author(s):  
Rafael Noguerol ◽  
Juan Carlos Unriza ◽  
Alberto Acevedo
Keyword(s):  
Sensitivity Analysis ◽  
Communication Systems ◽  
Leak Detection ◽  
Operating Conditions ◽  
Detection Sensitivity ◽  
Pipeline System ◽  
Data Preparation ◽  
System Sensitivity ◽  
Hydraulic Simulator ◽  
Oil Company

Determining the leak detection sensitivity for a particular system, or suggesting strategies to improve it are common challenges for leak detection professionals. As an alternative to statistical analysis, an empirical approach can be employed: use an offline hydraulic simulator to model the pipeline system, including all the inaccuracies due to the instruments and communication systems. Using such an approach the sensitivity can be inferred by running some scenarios representative of leak and non-leak conditions. Furthermore, not only can normal operating conditions be considered but also emergency and/or upset operating conditions can also be taken into account. Ecopetrol (the national Oil Company of Colombia) utilized this practical approach during the commissioning phase of a new pipeline allowing Ecopetrol to calculate the sensitivity prior to the commencement of operations. Analysis was also undertaken the results of which were recommendations on how to improve the system sensitivity. This paper describes the methodology; the construction of the hydraulic model; the assumptions made, and presents the final results. A discussion about the validity of the procedure and its generic application is also presented.

COMPARATIVE ANALYSIS OF WATER LEAK DETECTION SYSTEMS AND METHODOLOGIES

2016 ◽  
Vol 15 (9) ◽  
pp. 2063-2074
Author(s):  
Pedro Rosas Quiterio ◽  
Florencio Sanchez Silva ◽  
Ignacio Carvajal Mariscal ◽  
Jesus Alberto Meda Campana
Keyword(s):  
Comparative Analysis ◽  
Leak Detection ◽  
Detection Systems ◽  
Water Leak

Enhanced Detection Sensitivity with Pulsed Laser Digital Signal Integration Algorithm

2006 ◽  
Author(s):  
A.C.T. Quah ◽  
J.C.H. Phang ◽  
L.S. Koh ◽  
S.H. Tan ◽  
C.M. Chua
Keyword(s):  
Fault Localization ◽  
Pulsed Laser ◽  
Digital Signal ◽  
Detection Sensitivity ◽  
Signal Integration ◽  
Laser Operation ◽  
Frequency Range ◽  
Integration Algorithm ◽  
Detection Systems ◽  
Lock In

Abstract This paper describes a pulsed laser induced digital signal integration algorithm for pulsed laser operation that is compatible with existing ac-coupled and dc-coupled detection systems for fault localization. This algorithm enhances laser induced detection sensitivity without a lock-in amplifier. The best detection sensitivity is achieved at a pulsing frequency range between 500 Hz to 1.5 kHz. Within this frequency range, the algorithm is capable of achieving more than 9 times enhancement in detection sensitivity.

Modelling of Nitrification at the Mogden Treatment Works

1989 ◽  
Vol 21 (4-5) ◽  
pp. 305-314
Author(s):  
J. P. Lumbers ◽  
S. C. Cook ◽  
G. A. Thomas
Keyword(s):  
Sensitivity Analysis ◽  
Monte Carlo Simulation ◽  
River Basin Management ◽  
Independent Data ◽  
Activated Sludge Process ◽  
Basin Management ◽  
Alternative Control ◽  
Control Actions ◽  
Parameter Values ◽  
Generalised Sensitivity Analysis

An application of a dynamic model of the activated sludge process is described within the context of real-time river basin management. The model has been calibrated and validated on independent data and then applied to investigate losses of nitrification at the Mogden Works. Monte Carlo simulation and generalised sensitivity analysis were found to be effective ways of identifying appropriate parameter values and their importance. The prediction of unmeasured states such as the autotroph population enabled the effects of alternative control actions to be better understood and the most suitable measures found.

scholarly journals Addition of Flucytosine to Fluconazole for the Treatment of Cryptococcal Meningitis in Africa: A Multicountry Cost-effectiveness Analysis

2019 ◽  
Vol 70 (1) ◽  
pp. 26-29 ◽  
Author(s):  
Tinevimbo Shiri ◽  
Angela Loyse ◽  
Lawrence Mwenge ◽  
Tao Chen ◽  
Shabir Lakhi ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Cost Effectiveness ◽  
Cryptococcal Meningitis ◽  
Cost Effective ◽  
Immunodeficiency Virus ◽  
The Mean ◽  
The Cost ◽  
The Impact ◽  
Costing Analysis ◽  
Very High

Abstract Background Mortality from cryptococcal meningitis remains very high in Africa. In the Advancing Cryptococcal Meningitis Treatment for Africa (ACTA) trial, 2 weeks of fluconazole (FLU) plus flucytosine (5FC) was as effective and less costly than 2 weeks of amphotericin-based regimens. However, many African settings treat with FLU monotherapy, and the cost-effectiveness of adding 5FC to FLU is uncertain. Methods The effectiveness and costs of FLU+5FC were taken from ACTA, which included a costing analysis at the Zambian site. The effectiveness of FLU was derived from cohorts of consecutively enrolled patients, managed in respects other than drug therapy, as were participants in ACTA. FLU costs were derived from costs of FLU+5FC in ACTA, by subtracting 5FC drug and monitoring costs. The cost-effectiveness of FLU+5FC vs FLU alone was measured as the incremental cost-effectiveness ratio (ICER). A probabilistic sensitivity analysis assessed uncertainties and a bivariate deterministic sensitivity analysis examined the impact of varying mortality and 5FC drug costs on the ICER. Results The mean costs per patient were US $847 (95% confidence interval [CI] $776–927) for FLU+5FC, and US $628 (95% CI $557–709) for FLU. The 10-week mortality rate was 35.1% (95% CI 28.9–41.7%) with FLU+5FC and 53.8% (95% CI 43.1–64.1%) with FLU. At the current 5FC price of US $1.30 per 500 mg tablet, the ICER of 5FC+FLU versus FLU alone was US $65 (95% CI $28–208) per life-year saved. Reducing the 5FC cost to between US $0.80 and US $0.40 per 500 mg resulted in an ICER between US $44 and US $28 per life-year saved. Conclusions The addition of 5FC to FLU is cost-effective for cryptococcal meningitis treatment in Africa and, if made available widely, could substantially reduce mortality rates among human immunodeficiency virus–infected persons in Africa.

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