Solving Discounting Problem Using Piece-Wise Quadratic Fuzzy Numbers

The discounting problem is one of the important aspects in investment, portfolio selection, purchasing with credit, and many other financial operations. In this paper, a discounting problem using piecewise quadratic fuzzy numbers is proposed. The implementation of piecewise quadratic fuzzy numbers is described based on such operations. Fuzzy arithmetic and interval number arithmetic are used for computation. The close interval approximation of piecewise quadratic fuzzy numbers is used for solving the proposed discounting problem. This research article addresses the discounted investment for Year 1, Year 2, and Year 3. Additionally, the authors determine the cumulative discounted investment for different values of the parameter α ranging from 0 to 1. A discounting problem using piecewise quadratic fuzzy numbers is solved as a numerical example to illustrate the proposed procedure.

Efecto de las fallas de recubrimiento mecánico en los potenciales de protección catódica en ductos enterrados

El presente trabajo se enfoca en evaluar el efecto de las fallas de recubrimiento mecánico en los potenciales de protección catódica en ductos enterrados. Los estudios se llevaron a cabo en un ducto en sureste del país, con el objetivo de realizar un programa de mantenimiento preventivo y correctivo, alargando la vida útil de las instalaciones, manteniendo la seguridad y la confiabilidad de las mismas. Dado que la corrosión externa es una de las mayores causas de fugas en ductos subterráneos, las tuberías son protegidas contra estos efectos mediante una combinación de recubrimientos mecánicos y sistemas de protección catódica. Actualmente en la industria es la combinación más efectiva para controlar los efectos de corrosión externa en tuberías subterráneas. La técnica CIPS (Close Interval Potential Survey), se basa en la inspección para el análisis de los niveles de protección catódica en ductos enterrados. La técnica DCVG (Direct Current Voltage Gradient), es un sistema desarrollado para el análisis de defectos de recubrimiento en tuberías enterradas. El control de la corrosión depende de un equilibrio entre el estado del recubrimiento y los niveles de protección catódica. Para obtener niveles efectivos de protección catódica, los potenciales tubo-suelo deben ser mantenidos entre –850 mV “instant off” (subprotección) y –1250 mV “instant off” (sobreprotección). Esta meta solo puede ser alcanzada si existe un decaimiento controlado en el perfil de potencial en la tubería desde los puntos de máximo potencial (los rectificadores) a los puntos de mínimo potencial (las áreas más remotas de los rectificadores). El ritmo de decaimiento de potencial depende principalmente de la condición del recubrimiento de los ductos que se considera como el factor crítico para el correcto funcionamiento de los sistemas de protección catódica.

The Use of Fuzzy Estimators for the Construction of a Prediction Model Concerning an Environmental Ecosystem

As a variable system, the Lake of Kastoria is a good example regarding the pattern of the Mediterranean shallow lakes. The focus of this study is on the investigation of this lake’s eutrophication, analyzing the relation of the basic factors that affect this phenomenon using fuzzy logic. In the method we suggest, while there are many fuzzy implications that can be used since the proposition can take values in the close interval [0,1], we investigate the most appropriate implication for the studied water body. We propose a method evaluating fuzzy implications by constructing triangular non-asymptotic fuzzy numbers for each of the studied parameters coming from experimental data. This is achieved with the use of fuzzy estimators and fuzzy linear regression. In this way, we achieve a better understanding of the mechanisms and functions that regulate this ecosystem.

A Different Approach to High Resolution CP Evaluation

Assessing the effectiveness of Cathodic Protection (CP) in multiple pipeline corridors can be challenging. Close interval potential (CIS or CIPS) above ground CP surveys rely on interruption of all current sources that affect a particular pipeline and can be especially problematic in multi-pipe corridors involving several operators. Multi-pipe corridors can be very congested and complicated with numerous pipeline crossings and bonds. These circumstances can lead to difficulties in locating and ensuring the above ground survey is being conducted over the pipeline of interest. Inappropriate decisions surrounding the actual integrity of a particular pipeline have been made based on conventional pipe to soil surveys. The use of inline cathodic protection current measurement tools can eliminate a number of errors associated with above ground potential assessment techniques in multiple pipeline corridors and provide more accurate integrity data. CP ILI inspections can conclusively identify undocumented electrical connections to other structures on pipelines in such congested corridors. Active, unbeknownst bonds/connections will cause significant errors in CIS/CIPS data if not properly addressed during data acquisition. Additionally, information collected through the CIS technique is generalized since it is the average gradient being measured from all influencing adjacent lines. Information from an inline cathodic protection current measurement tool is specific to only the pipeline being inspected and therefore eliminates this uncertainty. This paper outlines an alternative approach to above ground close interval survey for assessing CP performance using inline inspection technology.

Application and Validation of Statistically Based Corrosion Growth Rates

When it comes to managing the integrity of corroded pipelines, operators are confronted with many difficult decisions — one of which is the level of conservatism that is used in pipeline integrity assessments. The financial implications associated with excavation, repair, rehabilitation, and inspection programs typically balance the level of conservatism that is adopted. More conservative approaches translate into more spending, so it is important that repair strategies developed based on the integrity assessment results are effective. As integrity assessment methodologies continue to evolve, so does the ability to account for local conditions. One development in recent years has been the ability to evaluate multiple MFL in-line inspections to determine areas of active corrosion growth, through the combined use of statistics, inspection signal comparisons, and engineering analysis. The authors have previously outlined one approach (commonly known as Statistically Active Corrosion (SAC)) that has been successfully used to identify areas of probable corrosion growth, predict local corrosion growth rates, and maximize the effectiveness of integrity assessments.[1] Validation of the SAC-predicted corrosion growth rates is important for establishing confidence in the process. This is achieved through inspection signal comparisons, integrating close interval survey (CIS) results, and (when possible) field verification. The means by which these methods are used for validating the SAC method are described in this paper.

Evaluation of Wireless Tools for Determining Contact Status Between a Casing and the Carrier Pipe

For more than half a century, cased crossings have been used to support oil and gas steel pipes for crossing highways, railways, or rivers. Leaks or ruptures of cased crossings have occurred that resulted in casualties and property damage. Unlike uncased pipes buried in soils, which can be assessed for external corrosion directly and indirectly, the presence of a steel casing wall makes it challenging, even if possible, to conduct these assessments. The effect of the casing wall on the external corrosion of the carrier pipe inside the annulus is not well understood; it is unclear what tools can be used to effectively inspect the cased pipes. Empirical experience from the pipeline industry has shown that a few tools can be used to detect the contact status between a casing and the carrier pipe, which can help assess the severity of the carrier pipe external corrosion. Unfortunately, the criteria used to detect a contact status vary by user for the same tool and thus, the effectiveness of these criteria is uncertain. This paper reports results from a recent study aimed at evaluating the effectiveness of AC current attenuation, AC voltage gradient, and close interval (potential) survey as tools for detecting the contact status between a casing and the carrier pipe.