Evaluation of Reliability Indices for Gas Turbines Based on the Johnson SB Distribution: Towards Practical Development

Recent advancements in computer engineering have provided effective solutions for processing and analyzing complex systems and big data. Consequently, the adjustment and standardization of this data play a crucial role in addressing issues related to the monitoring of industrial systems. In this study, we propose a reliability approach for gas turbines to identify and characterize their degradation using operational data. We introduce a method for adjusting turbine reliability data, which resolves the challenges associated with the nature of these operating data. This enables us to determine a mathematical function that models the relationships between turbine reliability parameters and evaluate the impact of reliability practices in terms of availability. Additionally, we determine the survival function and employ it as a lifespan distribution model by estimating the parameters of the Johnson SB function. Furthermore, we calculate the failure rates and mean time between good operations for this rotating machine under different operating conditions. The obtained results allow us to estimate the parameters of the distribution that best fit the turbine reliability data, which are validated through statistical and graphical tests. We assess the goodness-of-fit using mean square error and reliability tests such as Kolmogorov-Smirnov

3D Geomechanical Model Construction for Wellbore Stability Analysis in Algerian Southeastern Petroleum Field

The main objective of this research work was the wellbore stability evaluation of oil and gas wells based on a 3D geomechanical model, which as constructed using seismic inversion in a southeastern Algerian petroleum field. The seismic inversion model was obtained by using an iterative method and Aki and Richards approximation. Since the correlation between the inversion model and the log data was high at the wells, the reservoir was efficiently characterized and its lithology carefully discriminated in order to build a reliable 3D geomechanical model. The latter was further used to suggest the drilling mud weight window for the ongoing wells (well 5) and to examine the stability of four previously drilled wells. The main contribution of this study is providing a 3D geomechanical model that allows the optimization of drilling mud weight parameters so that a wellbore’s stability is guaranteed, on the one hand, and, on the other hand, so that the reservoir damage brought about by excessive surfactant use can be prevented. Indeed, the mud parameters are not just important for the drilling process’s effectiveness but also for logging operations. Since the tools have limited investigation diameters, with excessive use of surfactant, the invaded zone can become larger than the tools’ investigation diameter, which makes their logs unreliable. Hence, the 3D geomechanical model presented here is highly recommendable for the proposition of new wells, entailing less exploration uncertainty and more controllable productivity

Effects of Smoking Exposure in Infants on Gastroesophageal Reflux as a Function of the Sleep-Wakefulness State

International audienceObjective To determine whether perinatal smoking exposure is associated with gastroesophageal reflux (GER)-related changes in sleep-wakefulness states in neonates. Study design Thirty-one neonates. referred for the investigation of suspected GER, were recruited and underwent multichannel impedance-pH monitoring and synchronized 8- to 12-hour polysomnography. The infants' exposure to tobacco smoke was estimated by means of a urine cotinine assay. The total number. frequency (h(-1)), and mean duration (minutes) of GER-pH (reflux events detected by the pH electrode only) and GER-imp (reflux events with bolus movement detected by impedance) events were determined. Intergroup differences (smokingexposed group vs nonexposed group) were probed with nonparametric. unpaired Mann-Whitney U tests. A chi(2) test was used to assess a possible intergroup difference in bolus retrograde migration during GER-imp events. Results According to the urine cotinine assay, 21 of the 31 neonates had been exposed to cigarette smoke during the perinatal period. The number (and frequency) of GER-imp was significantly greater (P= .016) in the exposed group (29 [0-90]) than in the nonexposed group (12 [2-35]). Migration of the esophageal bolus from the distal segment to the most proximal segment was significantly more frequent (P= .016) in the exposed group (83% of GER) than in the nonexposed group (41%). The GER pattern associated with smoking exposure was particularly obvious during Rapid eye movement sleep. Conclusions The more frequent occurrence and greater proximal migration of GER-imp in the smoking-exposed group (especially during rapid eye movement sleep) may have clinical relevance. Smoking exposure is a preventable risk factor for limiting the occurrence of GER in neonates

Involvement of autonomic nervous activity changes in gastroesophageal reflux in neonates during sleep and wakefulness.

BACKGROUND: It has been suggested that disturbed activity of the autonomic nervous system is one of the factors involved in gastroesophageal reflux (GER) in adults. We sought to establish whether transient ANS dysfunction (as assessed by heart rate variability) is associated with the occurrence of GER events in neonates during sleep and wakefulness. METHODS: Nineteen neonates with suspected GER underwent simultaneous, synchronized 12-hour polysomnography and esophageal multichannel impedance-pH monitoring. We compared changes in HRV parameters during three types of periods (control and prior to and during reflux) with respect to the vigilance state. RESULTS: The vigilance state influenced the distribution of GER events (P<0.001), with 53.4% observed during wakefulness, 37.6% observed during active sleep and only 9% observed during quiet sleep. A significant increase in the sympathovagal ratio (+32%, P=0.013) was observed in the period immediately prior to reflux (due to a 15% reduction in parasympathetic activity (P=0.017)), relative to the control period. This phenomenon was observed during both wakefulness and active sleep. CONCLUSION: Our results showed that GER events were preceded by a vigilance-state-independent decrease in parasympathetic tone. This suggests that a pre-reflux change in ANS activity is one of the factors contributing to the mechanism of reflux in neonates

Ambient Vibration Techniques Applied to Explain Heavy Damages Caused in Corso (Algeria) by the 2003 Boumerdes Earthquake: Understanding Seismic Amplification Due to Gentle Slopes

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The Beni Haoua, Algeria, Mw 4.9 earthquake: source parameters, engineering, and seismotectonic implications

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