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3.4 Application Modelling of Reliability and Performance in Engineering Design 273. 274 3 Reliability and Performance in Engineering Design. to the DCS or PLC. For ex- ample, a PLC may control the flow of cooling water through part of a process, such as the reverse jet scrubber, but the SCADA system allows operators to change the set points for the...
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The Kolmogorov–Smirnov goodness-of-fit test The Kolmogorov–Smirnov (K–S) test is used to decide if a sample comes from a population with a specific distribu- tion. The K–S test is based on the empirical distribution function (e.c.d.f.) whereby, given N ordered data points Y 1 , Y 2. An attractive feature of this test is that the distribution of the K–S test...
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Nuclear Eng Design revised from Sandia Natl Lab Rep SAND88-2253C, and Nuclear Regulatory Commission Rep NUREG/CP-0097 5, pp 1–25 Pahl G, Beitz W (1996) Engineering design. Elsevier, New York Simon HA (1981) The sciences of the artificial. 294 3 Reliability and Performance in Engineering Design Steele AD, Leitch RR (1996) A strategy for qualitative model-based diagnosis. Zadeh LA (1973) Outline...
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Inherent availability can be defined as “the prediction of expected system per- formance or system operability over a period which includes the predicted system operating time and the predicted corrective maintenance down time”.. Achieved availability can be defined as “the assessment of system operability or equipment usage in a simulated environment, over a period which includes its predicted operating time...
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What is the economic loss of production in the event of systems A1 and A2 being down for 5 days as a result of downtime?. Relative lost time cost = 5 days day × 10%. Relative lost time cost = 5 days day × 60%. $60 , 000 Relative lost time cost. Would there be a difference in the calculations...
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In applying NPV, the net cash flows are usually available as input data, which are assumed to occur instantaneously at the ends of the periods t. Also usually known is an estimate of the discounting rate, i, to be used. While the point estimate of NPV is informative, in that one can determine if it is positive, negative, zero or...
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To obtain a reasonable measure of the process capability, the length of the time frame should be chosen such that it is long enough to reflect all the substantial sources of variation in the process. The pilot process output should be sampled in such a way that a ‘fair’. representation is obtained of the process over the chosen time frame....
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The effective capacities of multiple system operations or processes within the same engineering design installation are usually different. A bottleneck is a process that has the lowest effective capacity of any process in the designed installation and, thus, limits total output. Also, the focus on bottlenecks is the means to increasing throughput and, consequently, the mass-flow rate of product and...
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As with the two-state Markov model, the mathematical expressions for the multi- state Markov model, including supplementary variables indicating partial operation or a reduced efficiency of the system, are given in the following Markov multi-state model equations, according to Fig. 1 − μ f ( x )Δ t ] (4.72) λ j is the jth constant failure rate of the...
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Routine maintenance is the preventive action in maintenance that cares for the operational condition of equipment through inspection, adjustment, recording, monitoring, servicing and lubrication, to ensure that the equipment’s operational functions conform to the required limits of performance.. Evidently, this type of preventive action can only be directed towards the operational condition of equipment.. Thus, the way in which corrective...
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From the three fundamental principles of a maintenance strategy, it is evident that all required maintenance work is made up of one or more types of maintenance that accomplish specific technical benefits. As stated previously, it is the combination of these different types of maintenance that constitutes a maintenance strategy.. From an engineering design perspective, a maintenance strategy is the...
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Failure occurrence in the equipment.. Failure mode of the failed component.. Number of similar parts or components.. Although seemingly problematic from the perspective of complexity, the multiplic- ity of similar parts in each component, with usually a large number of similar com- ponents within each system, is in fact beneficial in characterising the demand for different kinds of spares. Furthermore,...
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However, because of the peculiar nature of these parameters, none are considered in this research, although it is essential to have a complete set of on-system and off-system indices to adequately assess system maintainability and the total mainte- nance burden.. Because BIT is applied within a system’s function, and at the same functioning speed, it affords the capability to detect...
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Operational Time. Time Period × Process Output MDC. Operational time. MDC = maximum dependable capacity. MDC = 1 × (constant representing capacity, C) Process output. Process output = 0 . Process output = 90% of MDC.. It is necessary to consider mean downtime (MDT) compared to the mean time to repair (MTTR). There is frequently confusion between the two and...
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It must be noted that this average output rate is expressed as a percentage of the pos- sible output that can be achieved at maximum design capacity and 100% utilisation.. It is thus an expression of the output capability of the plant as a whole, depending on the percentage capacity for each state of the plant, as a result of...
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Will catastrophic failure be evident in the control room?. Does other equipment need to be removed before access can be gained?. 4.3.1.2 System Performance Analysis and Simulation Modelling. Section 3.3.1.2 considered system performance within the context of designing for availability, which can be perceived as the combination of:. All these characteristics may serve as useful indicators in designing for availabil-...
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4.16 Flowchart of the Monte Carlo simulation pro- cedure (Law et al. The Monte Carlo simulation approach generates statistical estimates of the sys- tem output based on the given distributions of the inputs and error models. More effective sampling techniques such as the Latin hypercube and fractional fac- torial design can be used to reduce the amount of simulations (Hicks...
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Transition t g is pri—under this policy, each time t g is disabled, its age variable a g is reset but its indicator re-sampling variable r g remains equal to 1, and the firing time value γ 1 remains active, so that in the next enabling period an identical firing will result. The same value is maintained over different enabling...
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Returning to the initial quantitative example of designing for availability with the inclusion of preventive maintenance, Fig. 4.24 illustrates the MRSPN representation of the system (Bobbio et al. The generally distributed transition t f models the failure distribution of which the firing results in the system moving to place P down . Upon system failure, the preventive maintenance activity is...
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It is extremely important to examine critically whether the statement of the problem expresses the reality of the problem. Systems configuration: two coal slurry preparation, gasifier and gas cleaner (scrubber) lines in parallel, each with separate oxygen inputs into the gasifier.. (1) A coal plant feeds coal to two coal slurry preparation mills.. Problem definition: determine the reduction in plant...