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[en] The Bayesian network models of redundant systems including parallel system and voting system, taking account of common cause failure and imperfect coverage, are proposed. The Triple Modular Redundancy (TMR) and Double Dual Modular Redundancy (DDMR) control systems for subsea Blowout Preventer (BOP) are presented. By applying the proposed Bayesian network models, the reliability of subsea BOP control systems are evaluated at any given time, and the difference between posterior and prior probabilities of each single component given the system failure is obtained. The effects of coverage factor of redundant subsystem and failure rate of single component on reliability of systems are also researched. The results show that the DDMR control system has a little higher reliability than TMR system. To improve the reliability of subsea BOP control systems, the component failure rates of Ethernet switch (ES), programmable logic controller (PLC) and personal computer (PC) should be reduced for TMR system, whereas the failure rates of ES and PC should be reduced for DDMR system. The recovery mechanism of PLC, PC and ES subsystems, and PC and ES subsystems should be paid more attention for TMR and DDMR control systems, respectively.
[en] All the various sectors (i.e. Exploration and Production, Marketing and Refining, Petrochemicals and Transportation) of the petroleum industry impact the environment in their operations. Generally, the impact could come from accidental spills, routine effluent discharges, releases of wastes, etc into the environment. Some of the spills, discharges and wastes are common to the various sectors. Upstream operations in Nigeria involve exploration and production of crude oil and condensate, and tanker loading operations. Exploration for these hydrocarbons are handled by experts such as geologists, geophysicists and engineers in a technical process which consists of special surveys, e.g. seismic, gravimetric, magnetic and drilling of wells to locate the subsurface structure which contains the hydrocarbons. These surveys provide information on the characteristics and properties of the structure and its potential for hydrocarbon accumulation. Exploratory drilling is performed after the surveys to determine the nature and extent of potential hydrocarbon bearing reservoirs, as well as other factors relating to economic viability before production activities commence. All these can considerably impact on the environment. It is therefore advisable that environmental impact assessment be performed before exploration and development operations take place, especially in remote locations
[en] The Waste Isolation Pilot Plant (WIPP) is the U.S. Department of Energy's (DOE) mined geologic repository in southeastern New Mexico, USA.This site is designed for the permanent burial of transuranic radioactive waste generated by defense related activities.The waste produces gases when exposed to brine. This gas generation may result in increased pressures over time. Therefore, a future driller that unknowingly penetrates through the site may experience a blowout. This paper describes the methodology used to predict the resultant volumes of contaminated brine released
[en] The Petroleum Safety Authority Norway (PSA, formerly Norwegian Petroleum Directorate) took in 1999 the initiative to develop a method in order to assess trends and status for the risk levels in the Norwegian offshore petroleum industry. A method was developed, and a pilot study report was issued in April 2001, covering the period 1996-2000. Annual updates have been performed since then, and the latest report covers the period 1996-2004. The statistical approach is based on recording occurrence of near misses and relevant incidents, performance of barriers and results from risk assessments. Of similar importance is an evaluation of safety culture, motivation, communication and perceived risk. This is covered through the use of social science methods, such as questionnaire surveys and a number of interviews, audit and inspection reports as well as accident and incident investigations. There are also indicators for occupational accidents and occupational illness/-physical working environment factors. The focus is on the major hazard risk components for personnel staying on the offshore installations. An overview of the indicators used to illustrate these risk aspects is presented, followed by a discussion of the analytical approach used for these indicators. Results from the risk assessment for the Norwegian Continental Shelf in the period 1996-2004 are used throughout for illustration, and discussion of challenges
[en] The article highlights the current state of the issue and offers new patented technical solutions that eliminate shortcomings of the existing ones. A distinguishing feature of the new design solutions is the coexistence in safety devices (SD) of both blowout diaphragms and nonstandard safety valves, the moving masses of which do not affect the SD operation speed. Because of this, it is fully leakproof in normal situation and it opens fast enough in explosive scenario.
[en] It is well known that some coronal jets exhibit helical structures and untwisting. We attempt to inspect the origin of twist in a blowout jet. By means of multi-wavelength and multi-angle observations from Solar Dynamics Observatory (SDO) and Solar Terrestrial Relations Observatory-Ahead (STEREO-A), we firstly report a polar untwisting jet that is a blowout jet which leads to a jet-like coronal mass ejection. From the viewpoint of SDO, the jet shows clear untwisting behavior and two jet-spires. However, from the viewpoint of STEREO-A the jet actually comes from the whiplike prominence eruption and is followed by a white-light jet. Our observations indicate that twist in blowout jets may result from the erupting mini-prominences/mini-filaments in the jet base. (letters)
[en] Objectives: Endovascular treatment is effective in treating carotid blowout syndrome (CBS). We reviewed our experience in addressing CBS over eight years and presented an account of the treatment paradigm and management algorithm. Method: All cases of CBS from 2003 to 2010 with endovascular treatment performed in our center were reviewed. 15 CBS in 14 patients were recruited. Based on our management algorithm, treatment regimen was stratified into deconstructive or constructive methods. Their clinical presentations, angiographic features, angiographic and clinical outcomes were reviewed. Results: 10 patients were treated with deconstructive method by means of permanent vessel occlusion (PVO) and 4 patients were treated with constructive method by means of placement of covered stent (n = 3) or flow diverting device (n = 1). Immediate hemostasis was achieved in all cases. 7 (50%) patients, in whom 5 treated with PVO and 2 with covered stent, had favorable outcomes and survived at a median follow-up period of 4 months (range: 1–84 months). Conclusion: Permanent vessel occlusion remains the gold standard of treatment and tends to show a favorable long-term outcome. Off-label use of covered stent and flow-diverting device can produce satisfactory results should balloon occlusion test fail, but long-term follow up would be required for definitive assessment
[en] The self-guiding of relativistically intense but ultrashort laser pulses has been experimentally investigated as a function of laser power, plasma density, and plasma length in the blowout regime. The extent of self-guiding, observed by imaging the plasma exit, is shown to be limited by nonlinear pump depletion with observed self-guiding of over tens of Rayleigh lengths. Spectrally resolved images of the plasma exit show evidence consistent with self-guiding in the plasma wake. Minimal losses of the self-guided pulse resulted when the initial spot size was matched to the blowout radius.
[en] A wide region of beam parameters is numerically scanned and the dependence of wakefield properties on the beam length and current is clarified for the blowout regime of beam-plasma interaction. The main regimes of the plasma response are found, which qualitatively differ in the plasma behavior. To characterize the efficiency of the energy exchange between the beam and the plasma, the energy flux through the comoving window is introduced. Scalings of the energy flux for the linear plasma response and the main blowout regimes are studied. The most efficient energy transfer occurs in the so-called 'strong beam' regime of interaction. For this regime, analytical approximations for various aspects of the plasma response are obtained
[en] The effects of poisonous substances emitted from uncontrolled sour gas wells on cattle are described, from the perspective of a farmer whose cattle were exposed to such emissions. Two events in the Drayton Valley area led to exposure of cattle to toxins: a sour gas well blowout in 1977 (Amoco 7-10 well) occurring 40 km from the farm, and the Lodgepole blowout (Amoco Dome Brazeau River) in 1982 that occurred 38 km from the farm. Cattle were exposed to raw sour gas and sour gas well exhaust for 67 days during the Lodgepole blowout. A marked effect on the weaning weight and feeding performance of calves in years after the blowout was observed. Exposure of replacement heifers to sour gas well blowout emissions greatly increased the cull rate of the animals. 5 figs., 3 tabs