Supervision of Offshore Oil and Gas Exploration and Production and the Independence of Regulators as a Response to Major Accidents

ABSTRACT This article analyzes the reforms of offshore oil and gas (O&G) regulators in the United Kingdom (the UK), Norway, the United States of America (the USA), and the Netherlands after major accidents in the industry. The reforms introduced a measure to make regulators more independent, and to avoid conflicts of interest by separating economic and risk regulation. This research calls such measure “the functional separation criterion”. In order to identify what makes a regulator independent, this research goes beyond the offshore O&G industry to analyze the theory of independent regulators developed in the field of public administration. This approach evidences that, in contrast to the understanding of independent regulators used in the offshore O&G industry, the independence of regulators in the field of public administration is a multidimensional concept. A multidimensional assessment of the independence of offshore O&G regulators reveals findings that remain hidden if one uses a single and limited approach such as the functional separation criterion.

A method for three-dimensional modelling of the shear-clinching process

Three-dimensional modelling enables to determine the in-plane material flow in asymmetrical situation. Thus, the distortion of the sheets to be joined can be characterized more exactly. This study shows a method for building up a three-dimensional shear-clinching framework without damage criteria. In fact, the die-sided sheet in shear-clinching was designed as a pre-punched sheet and slugs. The material separation in the die-sided joining partner, which in two-dimensional simulation is often described by macro- and micromechanical fracture criteria, was realised in this study based on a defined contact condition. By means of a shear-cutting simulation, a correlation between the break angle and the separation stress was determined, which was used as a separation criterion in the shear-clinching simulation. The separation line was confirmed using post-particles. To validate this model, the results of the simulation using a quadratic single-point specimen were compared to the experiments with respect to the distortion of the joining partner. In general, the built three-dimensional framework provides for further tool developments with regard to the reduction of distortion in shear-clinching.

Independence and D-separation in Abstract Argumentation

We investigate the notion of independence in abstract argumentation, i.e., the question of whether the evaluation of one set of arguments is independent of the evaluation of another set of arguments, given that we already know the status of a third set of arguments. We provide a semantic definition of this notion and develop a method to discover independencies based on transforming an argumentation framework into a DAG on which we then apply the well-known d-separation criterion. We also introduce the SCC Markov property for argumentation semantics, which generalises the Markov property from the classical acyclic case and guarantees the soundness of our approach.

METHOD OF ESTIMATING THE TECHNICAL STATE OF THE COMBUSTION CHAMBER OF A GAS TURBINE INSTALLATION ON THE BASIS OF ARTIFICIAL INTELLIGENCE

Reliable and efficient operation of the gas-pumping unit to a large extent depends on the technical state of the combustion chamber. The poor technical state of the combustion chamber reduces not only the efficiency of the gas pumping unit, but also increases the harmful emissions to the environment of harmful substances such as nitrogen and carbon oxides. Therefore, the determination of the technical state of the combustion chamber by the results of observations on the operation of the gas turbine installation is an actual scientific task. As a result of the analysis of literary sources and experimental studies, it is established that the mediated parameters characterizing the technical state of the combustion chamber are the total concentration of nitrogen oxides and the mean square value of the vibration velocity of the combustion chamber body. Over time, the elements of the combustion chamber are degrading, which leads to a change in the signs of the technical state of the combustion chamber. Indicators of a technical state form a plane of signs, which, with the help of the neural network Kohonen, are divided into three areas, each of which corresponds to a certain technical state of the combustion chamber - "good", "acceptable", "permissible". A method for constructing separate curves based on genetic algorithms is developed to distinguish the areas of technical states. The equation of separate curves is taken as a polynomial of a certain degree. The developed method on the basis of the class separation criterion determines not only the parameters of the equation of a separate curve but also the structure of such an equation by minimizing the class separation criterion. With the help of the developed software of the task of the technical condition assessment of the combustion chamber, the plane of the signs is divided into three classes and separate split curves are constructed.

Optimization of Piecewise Conical Nozzles: Theory and Application

An optimization study based on computational fluid dynamics (CFD) in combination with Stratford's analytical separation criterion was developed for the design of piecewise conical contraction zones and nozzles. The risk of flow separation was formally covered by a newly introduced dimensionless separation number. The use of this separation number can be interpreted as an adaption of Stratford's separation criterion to piecewise conical nozzles. In the nozzle design optimization process, the risk of flow separation was reduced by minimizing the separation number. It was found that the flow-optimized piecewise conical nozzle did not correspond to a direct geometric approximation of an ideal polynomial profile. In fact, it was beneficial to reduce the flow deflection in the outlet region for a piecewise conical nozzle to increase the nozzle performance. In order to validate the novel design method, extensive tests for different nozzle designs were conducted by means of wind tunnel tests. The measured velocity profiles and wall pressure distributions agreed well with the CFD predictions.