Graeme Keith

Graeme Keith

København, Region Hovedstaden, Danmark
8 t følgere 500+ forbindelser

Om

- Advisor in the application of quantitative methods to risk management and strategy…

Artikler af Graeme

  • Probabilistic pitfalls in oil and gas exploration

    Probabilistic pitfalls in oil and gas exploration

    The oil and gas exploration community is well aware of the challenges it has forecasting how many wells will…

    25 Kommentarer
  • The inevitability of optimism

    The inevitability of optimism

    Nine out of ten transport infrastructure projects run over on cost. Actual costs are on average around 30% higher than…

    26 Kommentarer
  • Summer reading for risk analysis

    Summer reading for risk analysis

    Tom Körner is that rarest of breeds: a mathematician who can write. Even rarer, he’s really funny.

    22 Kommentarer
  • The redemption of risk management

    The redemption of risk management

    I confess. I have no love for risk matrices at all.

    6 Kommentarer
  • Reference-class forecasting for oil and gas exploration

    Reference-class forecasting for oil and gas exploration

    Probabilistic prediction of exploration volumes suffers from four fundamental systematic biases. These are Optimism…

    8 Kommentarer
  • Emerging from the muddle of matrices

    Emerging from the muddle of matrices

    You are exasperated by the ambiguity of subjective semi-quantitative scoring; infuriated by ranges that are too wide to…

    8 Kommentarer
  • Rehabilitating Risk Matrices

    Rehabilitating Risk Matrices

    This is a risk matrix used for reporting "Enterprise Risks". Risks - possible events that will have a negative impact…

    37 Kommentarer
  • The perils of extreme percentiles

    The perils of extreme percentiles

    Discussions around extreme percentiles abound. The oil and gas exploration community expends enormous effort exhausting…

    7 Kommentarer
  • Precisely vague

    Precisely vague

    Every year, in the search for new resources, the oil and gas industry commits tens of billions of dollars on the basis…

    1 Kommentar

Aktivitet

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Erfaring

  • Archer Integrated Risk Management Grafik

    Archer Integrated Risk Management

    Copenhagen, Capital Region, Denmark

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    Copenhagen Area, Denmark

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    Copenhagen

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    Copenhagen Area, Denmark

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    Copenhagen Area, Denmark

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    Copenhagen Area, Denmark

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    Copenhagen

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    Copenhagen Area, Denmark

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Uddannelse

Licenser og certificeringer

Erfaring med frivilligt arbejde

  • Board member

    The Danish Suzuki Institute

    8 år

    Børn

  • IDA Grafik

    Board member, Risk section

    IDA

    4 år

    Uddannelse

Udgivelser

  • Failure analysis of rotating equipment using root cause analysis

    Power-Gen

    Andre forfattere
  • Flow-generated pressure pulsations on oil & gas installations

    Proceedings of the 17th International Congress on Sound and Vibration

    Violent pressure pulsations in a pipeline system are usually the product of machinery such as reciprocating or screw compressors. Nonetheless, under certain conditions pressure pulsations vigorous enough to damage fittings and equipment may be generated by flow alone. This paper describes the mechanisms by which these phenomena may arise, how they may be modelled and the conclusions that may be drawn from these models in terms of treating phenomena or, better still, avoiding them in the first…

    Violent pressure pulsations in a pipeline system are usually the product of machinery such as reciprocating or screw compressors. Nonetheless, under certain conditions pressure pulsations vigorous enough to damage fittings and equipment may be generated by flow alone. This paper describes the mechanisms by which these phenomena may arise, how they may be modelled and the conclusions that may be drawn from these models in terms of treating phenomena or, better still, avoiding them in the first place.

  • Friction factor jump in honeycomb seals explained by flow-acoustic interactions

    ASME GT2009-60337

    In a series of experiments over flat plate honeycomb seal surfaces with deep cavities, Ha and Childs [1] have reported, under certain conditions, sudden “jumps” in the friction factor, which possibly could seriously impair honeycomb seal rotordynamic performance. This phenomenon was never fully explained before. In this study, the results have been investigated both analytically and computationally in the light of the Strouhal number dependency, and it was found that the friction factor jump…

    In a series of experiments over flat plate honeycomb seal surfaces with deep cavities, Ha and Childs [1] have reported, under certain conditions, sudden “jumps” in the friction factor, which possibly could seriously impair honeycomb seal rotordynamic performance. This phenomenon was never fully explained before. In this study, the results have been investigated both analytically and computationally in the light of the Strouhal number dependency, and it was found that the friction factor jump phenomenon is nearly uniquely correlated with the Strouhal number of the flow. This lends strong credence to the hypothesis that the friction factor jump is due to a flow-acoustic interaction. Indeed, the measured friction factors were found to jump at the exact Strouhal Numbers where the energy transfer rate from the flow mode to the acoustic mode were at a maximum. CFD direct numerical simulations at the configurations of friction factor jump also demonstrate a lock-in between the acoustic and vortex shedding frequencies.

    Andre forfattere
  • High wavenumber acoustic radiation from a thin-walled axisymmetric cylinder

    Journal of Sound and Vibration 255 (1) 129-146

    The radiation from an axisymmetric thin-walled cylinder is determined by using the Geometrical Theory of Di!raction. The non-uniformities associated with this theory are corrected by using uniform asymptotic techniques, and the farfield velocity potential is calculated everywhere. The theory provides a paradigm for interpretation of geometrical features of the directivity pattern in the farfield, and the results are discussed from this perspective. Comparison is made with analytical results…

    The radiation from an axisymmetric thin-walled cylinder is determined by using the Geometrical Theory of Di!raction. The non-uniformities associated with this theory are corrected by using uniform asymptotic techniques, and the farfield velocity potential is calculated everywhere. The theory provides a paradigm for interpretation of geometrical features of the directivity pattern in the farfield, and the results are discussed from this perspective. Comparison is made with analytical results obtained by using the Wiener-Hopf technique and the agreement is shown to be excellent. In particular, the uniform asymptotic techniques give the correct farfield form of the velocity potential in the principal lobe and predict the value at the peak of the principal lobe very accurately. This work provides a theoretical basis for the investigation of the radiation from asymmetric cylinder apertures, which has important applications in the noise reduction of aircraft, and which is discussed in a companion paper.

    Andre forfattere
  • High wavenumber acoustic radiation from a thin-walled scarfed cylinder

    Journal of Sound and Vibration 255 (1) 147-160

    The analysis of the radiation from an axisymmetric duct using the Geometrical Theory of Di!raction and uniform asymptotics, presented in a companion paper, is extended to an asymmetric, scarfed cylinder. The generic theory from the application to axisymmetric cylinders is briefly recapitulated and the geometrical calculations necessary for the analysis of the scarfed cylinder are presented in detail. The scarfed cylinder is used as a model for a novel technique of noise reduction in modern…

    The analysis of the radiation from an axisymmetric duct using the Geometrical Theory of Di!raction and uniform asymptotics, presented in a companion paper, is extended to an asymmetric, scarfed cylinder. The generic theory from the application to axisymmetric cylinders is briefly recapitulated and the geometrical calculations necessary for the analysis of the scarfed cylinder are presented in detail. The scarfed cylinder is used as a model for a novel technique of noise reduction in modern aeroengines in which the intake is directed a little upward to try and direct noise radiation away from the ground. We do not carry out a full parameter study, but preliminary results from this work suggest the technique has significant potential noise reduction benefits.

    Andre forfattere
  • Practical Computational Aeroacoustics for Compact Surfaces in Low Mach Number Flows

    Acta Acustica 97 14-23

    Sound generation has been widely studied using numerical hybrid methods. The aim of this paper is to introduce a flexible procedure where the acoustic source data may be synthesized and stored from commercially available Computational Fluid Dynamics (CFD) codes and later used to predict radiated noise. Different applications will require either analytical or numerical methods for the radiation calculations. Attention is restricted to low Mach number flows where the noise generation is dominated…

    Sound generation has been widely studied using numerical hybrid methods. The aim of this paper is to introduce a flexible procedure where the acoustic source data may be synthesized and stored from commercially available Computational Fluid Dynamics (CFD) codes and later used to predict radiated noise. Different applications will require either analytical or numerical methods for the radiation calculations. Attention is restricted to low Mach number flows where the noise generation is dominated by the interaction of the flow with a surface with at least one characteristic dimension short compared to the wavelength of interest. This makes it possible to focus on the surface source term of the Ffowcs Williams-Hawkings equation. In this paper, in order to illustrate the basic method for storing and utilizing data from the CFD analysis, the flow past a circular cylinder at a Reynolds number of Re = 1.4. 105 will be studied, where the cylinder is compact and therefore the analytical free-space Green's function may be used.

    Andre forfattere
    • Ainara Pradera-Mallabiabarrena
  • Problems and solutions in the application of the Parabolic Wave Equation to outdoor noise propagation prediction

    Proceed- ings of the Joint Baltic-Nordic Acoustical Meeting

  • Rooting out causes for failure analysis

    Touch Oil & Gas Review 2011

    The Deepwater Horizon disaster was a terrible reminder of the consequences of equipment failure on facilities operating in challenging environments. Thankfully catastrophes on the scale of the Deepwater Horizon are rare, but equipment failure is a daily occurrence on installations around the globe. The consequences range from short unexpected downtime, to a total stop on production, from a brief burst of flaring to lasting environmental damage and from the momentary discomfiture of a worker to…

    The Deepwater Horizon disaster was a terrible reminder of the consequences of equipment failure on facilities operating in challenging environments. Thankfully catastrophes on the scale of the Deepwater Horizon are rare, but equipment failure is a daily occurrence on installations around the globe. The consequences range from short unexpected downtime, to a total stop on production, from a brief burst of flaring to lasting environmental damage and from the momentary discomfiture of a worker to incapacity or death.

    Whenever equipment fails to meet expectations or fails altogether, we must understand what went wrong so that we can safeguard against it ever happening again. A good explanation not only helps you prevent a failure from reoccurring it can help identify systematic weaknesses that might result in other failures.

    Se udgivelse
  • The effects of diffrac- tion from double layer arrays combined with Statistically Optimal Near- field Acoustical Holography

    Proceedings of the 15th International Congress on Sound and Vibration

    Andre forfattere
  • The use of microperforated plates to attenuate cavity resonances

    Journal of the Acoustical Society of America 120 (4) 1851-1858

    The use of microperforated plates to introduce damping in a closed cavity is examined. By placing a microperforated plate well inside the cavity instead of near a wall as traditionally done in room acoustics, high attenuation can be obtained for specific acoustic modes, compared with the lower attenuation that can be obtained in a broad frequency range with the conventional position of the plate. An analytical method for predicting the attenuation is presented. The method involves finding…

    The use of microperforated plates to introduce damping in a closed cavity is examined. By placing a microperforated plate well inside the cavity instead of near a wall as traditionally done in room acoustics, high attenuation can be obtained for specific acoustic modes, compared with the lower attenuation that can be obtained in a broad frequency range with the conventional position of the plate. An analytical method for predicting the attenuation is presented. The method involves finding complex eigenvalues and eigenfunctions for the modified cavity and makes it possible to predict Green’s functions. The results, which are validated experimentally, show that a microperforated plate can provide substantial attenuation of modes in a cavity. One possible application of these findings is the treatment of boiler tones in heat-exchanger cavities.

    Andre forfattere
    • Benjamin Fenech
    • Finn Jacobsen
  • Whirl frequency dependent Alford forces in axial compressors

    Proceedings of International Gas Turbine Institute

    Explicit closed form expressions are derived for the whirl frequency dependence of the Alford force in an axial compressor operating in steady-state away from the onset of rotating stall. The analysis includes the compressor flow dynamics using the Moore-Greitzer approximation. By asymptotic expansion in terms of the whirl orbit amplitude, expressions for the direct and cross-coupling impedance are obtained analytically. Several components in the cross-coupling impedance are shown to change…

    Explicit closed form expressions are derived for the whirl frequency dependence of the Alford force in an axial compressor operating in steady-state away from the onset of rotating stall. The analysis includes the compressor flow dynamics using the Moore-Greitzer approximation. By asymptotic expansion in terms of the whirl orbit amplitude, expressions for the direct and cross-coupling impedance are obtained analytically. Several components in the cross-coupling impedance are shown to change phase as the whirl frequency transits the rotating stall frequency. This implies that for a given compressor design the Alford force can be stabilizing or destabilizing depending on flow rate and whirl frequency. Further, the analysis shows that the coupling between mean flow quantities and rotor whirl is of second order. Thereby, the present asymptotic expansion results in a fluid-structure coupling model, which is consistent in accuracy with usual linearized rotordynamic analysis.

    Andre forfattere

Fag/kurser

  • Advanced Decision Analysis with Portfolio and Project Modelling

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  • Cambridge University, Judge Business School, Executive Education, Corporate Finance.

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  • Lloyd's Register Leadership Development Programme

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  • Petroleum Risk and Decision Analysis

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  • Stanford Strategic Decision and Risk Management: Strategic Portfolio Decisions

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Sprog

  • English

    Modersmåls- eller tosprogsfærdighed

  • Danish

    Modersmåls- eller tosprogsfærdighed

  • Norwegian

    Begrænset praktisk færdighed

  • French

    Begrænset praktisk færdighed

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