Tropical cyclones (TCs) are the most destructive weather systems that form over the tropical oceans, with 90 storms forming globally every year. The timely detection and tracking of TCs are important for advanced warning to the affected regions. As these storms form over the open oceans far from the continents, remote sensing plays a crucial role in detecting them. Here we present an automated TC detection from satellite images based on a novel deep learning technique. In this study, we propose a multi-staged deep learning framework for the detection of TCs, including, (i) a detector -Mask Region-Convolutional Neural Network (R-CNN), (ii) a wind speed filter, and (iii) a classifier -CNN. The hyperparameters of the entire pipeline is optimized to showcase the best performance using Bayesian optimization. Results indicate that the proposed approach yields high precision (97.10%), specificity (97.59%), and accuracy (86.55%) for test images.
Rigid subsea jumper systems are typically used as interface between subsea structures and are required to accommodate significant static and dynamic loads. Due to constraints imposed by in-line planar jumpers (e.g. U shaped and M shaped jumpers), the industry is shifting towards the use of multi-planar jumper systems (e.g., Z-shaped jumpers). These multi-planar jumper systems have increased tolerance to end displacements and can be tailored to accommodate cyclic end motions of subsea structures. Multi-planar systems, however, come with unique challenges of their own including the coupling of flexural and torsional responses under vortex induced vibrations (VIV), fluid induced vibration (FIV) and slugging. In particular, the development of hydrodynamic slug flow is a common occurrence in oil and gas pipelines. It is understood to be initiated by instabilities of wave on the gas-liquid interface. It is also understood that slug flows are the source of vibration within pipework when a change of direction occurs e.g. 90° bend at a subsea riser base or top side piping. In standard slug flow vibration analysis, averaged slug frequency and length are used to calculate the force generated. In the case of a multi-planar rigid jumper, several changes of direction occur within a short length of pipe. After each bend the characteristics of the slug flow are modified. It is necessary to accurately capture these changes in order to reproduce the forces generated at critical points along the jumper length. This paper presents a methodology for analyzing slugging induced fatigue that has been developed in an on-going study undertaken by MCS Kenny for design of multi-planar rigid jumper systems. In this methodology, Computational Fluid Dynamics (CFD) is used to accurately simulate the flow within the jumper and provide pressure fluctuations on the internal pipe wall for the vibration analysis. The pressure fluctuations are then incorporated in a Finite Element (FE) model of the jumper system and further used to determine the slugging fatigue damage. CFD (Star-ccm+) and FE (Flexcom, ABAQUS) software programs are used to accurately capture the response of the jumper system. Key conclusions and challenges overcome during the course of this study are presented herein.
Evaluation of corroded chain link for continued use or life extension is a challenging task for the industry. ABS, together with fifteen (15) participating organizations, initiated the Fatigue of Corroded Chains (FoCCs) Joint Industry Project (JIP) in 2016. The objective of the FoCCs JIP is to investigate methodologies for assessing remaining fatigue life of the corroded mooring chain used for floating production systems. The JIP scope includes fatigue testing in labs and finite element analysis (FEA) of corroded chain samples retrieved from six floating production facilities in West Africa and the North Sea. The participating organizations include oil majors, chain manufactures, consulting firms, and classification societies, which represent a pool of broad range of mooring knowledge and experience. Knowledge gained from the JIP will be summarized and used toward the development of guidance notes for assessing fatigue life of corroded mooring chain for the industry. Six sets of mooring chain samples with different corrosion conditions have been collected, cleaned and digitally scanned for fatigue testing and FEA. Procedures for testing and analysis have been developed with the objective of establishing commonly accepted methods. Different FEA procedures have been studied for making a better prediction of stress ranges of the corroded chain links. The findings from the fatigue testing and FEA will be utilized as basis for further development of the methods for fatigue assessment of corroded mooring chain. This paper summarizes the tests and FE analysis work for the selected chain samples. The JIP research work has found that corrosion, either general corrosion or local/pitting corrosion, can significantly reduce the chain fatigue capacity. The location and the geometry of corrosion pits have more impact on fatigue lives than the pit size. The JIP study has shown that FE analysis is an effective tool to capture the hot spot of corroded chain links and can provide insight in their fatigue performance. Different methods on the assessment of the stress range of a hot spot are compared and discussed.
The share of electronic resources in library subscriptions has been increasing over a period of time. Academic institutions worldwide spend significant amounts on electronic resources, including e-journals, databases, and eBooks. Global research indicates that the management of electronic resources is very complex, and the workflows associated with them differ from the workflow of print resources. Although electronic resources have been around for almost two decades, librarians are still trying to figure out the most effective way to handle them. The study suggests that many non-compatible stand-alone systems are used to manage electronic resources. Library management systems (LMS) and library services platforms (LSPs) cannot manage electronic resource workflow. Electronic Resource Management Systems (ERMS) can be used to manage electronic resource workflow. However, cost is an important factor in not using commercial ERMS. This study examines the implementation of open-source ERMS CORAL in the Central Library, IIT Delhi. It discusses the steps involved in the implementation stages and the problems faced while implementing the system. It also discusses the features of CORAL. This study also finds improvements in electronic resource management after the implementation of ERMS CORAL. This study will be beneficial for those institutes that are looking for the implementation of CORAL.
To date, there are no publicly available, validated tools or industry accepted guidelines for the assessment of Vortex-Induced Vibration (VIV) fatigue of rigid Jumper (spool) systems. The existing state of practice has been to treat rigid jumper systems as free spanning pipelines and apply the associated design principles in DNV GL recommended practice DNV-RP-F105/DNVGL-RP-F105 (Free Spanning Pipelines). However, widely used rigid jumper systems such as the M-shape jumper systems are subjected to complex flow fields around their legs and bends and fall outside of the test data used to generate the free-span response model in DNV GL Recommended Practice (RP). A Joint Industry Project (JIP) ‘Jumper VIV JIP’ that included BP, ExxonMobil, Petrobras, Saipem and DNV GL was conducted between Dec. of 2014-2016 to collectively tackle the technical issues related to the VIV design of rigid jumper systems. Through the JIP study, measured responses from ExxonMobil's jumper tow test data were used to develop new response curves for jumper systems in pure-current condition. Curves for in-line and cross-flow responses were initially developed by classifying the measured responses into in-line or cross-flow directions and compared against the existing DNVGL-RP-F105 response curves. Due to potential ambiguity in classification and application to Jumper Design, a more general curve that does not rely on directional classification has also been generated. Due to the differences in behavior of rigid jumper systems to that of free spanning pipelines, a new VIV guidance report was developed as part of the JIP deliverable. Principles and philosophies in the DNV-RP-F105 were followed in the development, but with the intent of identifying unique behavior of jumper systems for a subsequent update of the RP. This paper presents the Guidance notes from the JIP and forms the first release of Jumper VIV fatigue assessment approach to the Industry. ExxonMobil's model test data, the only known test data available in the industry, was used in the development of unique response model and the new design guidance. The paper includes the new response model along with VIV screening, safety factors and unique considerations required for fatigue assessment of jumper systems.
Recognizing the need to address the challenges associated with the VIV assessment of rigid jumpers, a joint industry project (JIP) was launched in December 2014. The JIP was based on the model test data supplied by ExxonMobil. Through the JIP study, measured responses from tow tests were used to develop new response curves for jumper systems and compared against the existing DNV GL-RP-F105 curves. This paper presents details of the validation of model test data; processing of test data for response curve development; classification and interpretation of jumper response and; the two new response models developed for VIV assessment of rigid jumper systems. The response model developed through the Jumper VIV JIP forms the first of its kind for the VIV of non-straight (complex) pipe systems.
Vortex‐induced vibration (VIV) fatigue is one of the failure mechanisms of riser systems. Failure occurs due to the fatigue of the structure in vibration. VIV is caused by the motion of risers or other structures to shed vortices when exposed to fluid flow (such as currents and waves) impinging on the structure. The response of the structure is dependent on the natural frequencies of the structure and the frequency at which the structure sheds vortices (shedding frequency). Several physical quantities affect the VIV response such as the dimensions, stiffness, damping, and mass of the structure. VIV results in catastrophic failure of the riser system and is a critical that either the structure by design has low fatigue damage due to VIV or some external VIV suppressing devices are used to ensure safe operations. This article discusses the theory/concepts of VIV and the unique aspects of each riser system (TTRs, SCRs, flexibles, etc.) that need to be accounted for in the fatigue evaluation. The final section of this article introduces the typical suppressing devices that are used. This article focuses on the concepts relevant for riser VIV, and further reading is presented toward the end, for those readers interested in gaining more in‐depth understanding of the topic.
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