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.

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.

Avoidance of Slack Flow in Liquid Pipelines

2004 ◽  
Author(s):  
Te Ma ◽  
Oliver O. Youzwishen ◽  
Michael Hylton
Keyword(s):  
Detection System ◽  
Pressure Head ◽  
Pressure Control ◽  
Leak Detection ◽  
Operating Conditions ◽  
Pipeline System ◽  
Hydraulic Analysis ◽  
Valley Bottom ◽  
Effective Manner ◽  
Pump Stations

There are many existing liquid transmission pipelines that have significant changes in elevation along their route, making them susceptible to operating at “slack flow” conditions. Slack flow occurs in a pipeline when the pipeline pressure falls below the vapor pressure of that liquid (i.e. the pressure head decreases below the elevation at a certain point and causes the gauge pressure at that point to drop below zero atmosphere). Separation of the fluid column occurs, which can result in leak detection system inaccuracy and poor pressure/flow control during pigging operations. The designs of older pipelines typically did not address the slack flow issue. In order to eliminate the occurrence of slack flow, some method of pressure control is necessary, such as the installation of a pressure regulator station (PRS). In this paper a case study is used to demonstrate how a detailed hydraulic analysis was utilized in the design of an effective PRS, to eliminate slack flow. The subject pipeline system was approximately 800 km in length; with six pump stations and one terminal tank farm. One section of the pipeline contained an elevation difference of more than 1000 m (between mountain top and river valley bottom), creating slack flow operating conditions. A decision was made by the pipeline operator to prevent (potential) over pressurization at the lowest point on the pipeline. A secondary goal was to upgrade the leak detection system by eradicating the slack flow operation. Designing and installing a PRS and an over-pressure safety valve station achieved both of these goals. The PRS design, operation philosophy and safety philosophy development utilized information derived from a transient hydraulic simulation of the pipeline, using a hydraulic pipeline simulator (HPS). By using transient hydraulic analysis, an optimized solution to slack flow and over-pressuring on a liquids pipeline with large elevation differences, was achieved. By installing a PRS in an optimized location the pipeline operator has increased the reliability of leak detection and reduced the risks of over-pressuring, in a safe, cost effective manner.

Pseudo-Dynamic Fault Isolation Technique Using Backside Emission Microscopy – Case Study, Where All Other Methods Fail

2002 ◽  
Author(s):  
Yoav Weizman ◽  
Ezra Baruch ◽  
Michael Zimin
Keyword(s):  
Failure Analysis ◽  
Process Variations ◽  
Fault Isolation ◽  
Operating Conditions ◽  
Detection Sensitivity ◽  
Isolation Technique ◽  
Root Cause ◽  
Emission Microscopy ◽  
Failure Location ◽  
Noisy Background

Abstract Emission microscopy is usually implemented for static operating conditions of the DUT. Under dynamic operation it is nearly impossible to identify a failure out of the noisy background. In this paper we describe a simple technique that could be used in cases where the temporal location of the failure was identified however the physical location is not known or partially known. The technique was originally introduced to investigate IDDq failures (1) in order to investigate timing related issues with automated tester equipment. Ishii et al (2) improved the technique and coupled an emission microscope to the tester for functional failure analysis of DRAMs and logic LSIs. Using consecutive step-by-step tester halting coupled to a sensitive emission microscope, one is able detect the failure while it occurs. We will describe a failure analysis case in which marginal design and process variations combined to create contention at certain logic states. Since the failure occurred arbitrarily, the use of the traditional LVP, that requires a stable failure, misled the analysts. Furthermore, even if we used advanced tools as PICA, which was actually designed to locate such failures, we believe that there would have been little chance of observing the failure since the failure appeared only below 1.3V where the PICA tool has diminished photon detection sensitivity. For this case the step-by-step halting technique helped to isolate the failure location after a short round of measurements. With the use of logic simulations, the root cause of the failure was clear once the failing gate was known.

scholarly journals Sensitivity Analysis of OTEC-CC-MX-1 kWe Plant Prototype

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2585
Author(s):  
Jessica Guadalupe Tobal-Cupul ◽  
Estela Cerezo-Acevedo ◽  
Yair Yosias Arriola-Gil ◽  
Hector Fernando Gomez-Garcia ◽  
Victor Manuel Romero-Medina
Keyword(s):  
Sensitivity Analysis ◽  
Experimental Tests ◽  
Caribbean Sea ◽  
Ocean Model ◽  
Operating Conditions ◽  
Working Fluid ◽  
Ocean Energy ◽  
Mexican Caribbean ◽  
Water Temperature Data ◽  
Mass Flows

The Mexican Caribbean Sea has potential zones for Ocean Thermal Energy Conversion (OTEC) implementation. Universidad del Caribe and Instituto de Ciencias del Mar y Limnologia, with the support of the Mexican Centre of Innovation in Ocean Energy, designed and constructed a prototype OTEC plant (OTEC-CC-MX-1 kWe), which is the first initiative in Mexico for exploitation of this type of renewable energy. This paper presents a sensitivity analysis whose objective was to know, before carrying out the experimental tests, the behavior of OTEC-CC-MX-1 kWe regarding temperature differences, as well as the non-possible operating conditions, which allows us to assess possible modifications in the prototype installation. An algorithm was developed to obtain the inlet and outlet temperatures of the water and working fluid in the heat exchangers using the monthly surface and deep-water temperature data from the Hybrid Coordinate Ocean Model and Geographically Weighted Regression Temperature Model for the Mexican Caribbean Sea. With these temperatures, the following were analyzed: fluctuation of thermal efficiency, mass flows of R-152a and water and power production. By analyzing the results, we verified maximum and minimum mass flows of water and R-152a to produce 1 kWe during a typical year in the Mexican Caribbean Sea and the conditions when the production of electricity is not possible for OTEC-CC-MX-1 kWe.

scholarly journals Critical Review of EMC Standards for the Measurement of Radiated Electromagnetic Emissions from Transit Line and Rolling Stock

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 759
Author(s):  
Andrea Mariscotti
Keyword(s):  
Time Distribution ◽  
Communication Systems ◽  
Electromagnetic Compatibility ◽  
Transportation Systems ◽  
Operating Conditions ◽  
Rolling Stock ◽  
Intrinsic Variability ◽  
Statistical Characterization ◽  
Electromagnetic Emissions

Accurate and comprehensive methods for the assessment of radiated electromagnetic emissions in modern electric transportation systems are a necessity. The characteristics and susceptibility of modern victim signaling and communication radio services, operating within and outside the right-of-way, require an update of the measurement methods integrating or replacing the swept frequency technique with time domain approaches. Applicable standards are the EN 50121 (equivalent to the IEC 62236) and Urban Mass Transport Association (UMTA) with additional specifications from project contracts. This work discusses the standardized methods and settings, and the representative operating conditions, highlighting areas where improvements are possible and opportune (statistical characterization of measurement results, identification and distinction of emissions and line resonances, and narrowband and broadband phenomena). In particular for the Electromagnetic Compatibility (EMC) assessment with new Digital Communication Systems, the characterization of time distribution of spectral properties is discussed, e.g., by means of Amplitude Probability Distribution and including time distribution information. The problem of determination of site and setup uncertainty and repeatability is also discussed, observing on one hand the lack of clear indications in standards and, on the other hand, the non-ideality and intrinsic variability of measurement conditions (e.g., rolling stock operating conditions, synchronization issues, and electric arc intermittence).

Efficiency and Sensitivity Analysis of Cavern-Based CAES Systems During off-Design Operating Conditions

2021 ◽  
pp. 177-199
Author(s):  
Mehdi Ebrahimi ◽  
David S.-K. Ting ◽  
Rupp Carriveau ◽  
Andrew McGillis ◽  
David Brown
Keyword(s):  
Sensitivity Analysis ◽  
Operating Conditions

Auto-pipeline

2021 ◽  
Vol 14 (11) ◽  
pp. 2563-2575
Author(s):  
Junwen Yang ◽  
Yeye He ◽  
Surajit Chaudhuri
Keyword(s):  
Reinforcement Learning ◽  
Recent Work ◽  
Pipeline System ◽  
Complex Data ◽  
Data Preparation ◽  
Significant Progress ◽  
Database Table ◽  
End To End

Recent work has made significant progress in helping users to automate single data preparation steps, such as string-transformations and table-manipulation operators (e.g., Join, GroupBy, Pivot, etc.). We in this work propose to automate multiple such steps end-to-end, by synthesizing complex data-pipelines with both string-transformations and table-manipulation operators. We propose a novel by-target paradigm that allows users to easily specify the desired pipeline, which is a significant departure from the traditional by-example paradigm. Using by-target, users would provide input tables (e.g., csv or json files), and point us to a "target table" (e.g., an existing database table or BI dashboard) to demonstrate how the output from the desired pipeline would schematically "look like". While the problem is seemingly under-specified, our unique insight is that implicit table constraints such as FDs and keys can be exploited to significantly constrain the space and make the problem tractable. We develop an AUTO-PIPELINE system that learns to synthesize pipelines using deep reinforcement-learning (DRL) and search. Experiments using a benchmark of 700 real pipelines crawled from GitHub and commercial vendors suggest that AUTO-PIPELINE can successfully synthesize around 70% of complex pipelines with up to 10 steps.

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