Reference no: EM132690570

MREGC5103 Advanced Reliability - Federation University

Q1. Regional planners are designing a standard water reticulation system for use in multiple regions (Water Supply Areas) that have arable land and are subject to fire risk. The concept is to provide a stable supply of untreated water within each Water Supply Area for stock, dairy, agriculture, firefighting, and domestic use (but not for drinking or cooking). The water will be reticulated by an independent network for each Water Supply Area. To the maximum extent possible, each network will have the same equipment for economies of scale assumptions.
The source of supply is assumed to be able to meet demand and is not included in the scope of analysis.

As part of the design, the planners need an understanding of the reliability of a typical network.

The water is reticulated by 3 pipelines, each 5KM long with a booster pump every 500 metres. Each booster pump unit consist of 2 motors and 1 pump. Each booster pump unit has a control box mounted next to it that contains its power switching contactors and electronics box. All the control boxes are computer controlled from the pump station control room. Each of the 3 pipelines operate for 16 hours and are then idle for 8 hours. Routine inspections are carried out on the motor/gearboxes and tests are performed on the local control boxes of each conveyor during its idle period. The 3 pipelines run in such a way that two are always operating with one being idle and undergoing maintenance.

Task
Develop a simple mission profile for the 3 pipelines over a 24 hour period. It should be a simple bar diagram representation that shows the 3 pipelines running such that two are always operating.

You are asked to briefly consider the likely environmental factors that will affect the various types of equipment failure rates at different stages in the mission profile you have created.

Starting with the Motor, consider whether the motor's failure rates will be operating or non-operating at each mission stage. Tabulate the environmental factors and briefly describe in qualitative terms how each factor will impact the failure rates. You can use terms such as ‘minimal effect', ‘large effect' etc. Use the format of the example table below in your answer book.
Note: this is not asking about effect on component life but on failure rates.

MOTOR	Mission Stage 1	Mission Stage 2	Mission Stage 3	etc
Is failure rate Op/Nonop ?	Op	Op	Nonop
Environmental Factor 1	Major effect	Negligible	etc
Environmental Factor 2	etc	etc	etc

Environmental Factor 3
etc

Briefly describe the difficulties in inspecting each item of equipment thoroughly.

Failure records show that over a two-year period there have been the following total numbers of failures in the various equipment types.

Motors	131
Pumps	33
Control Boxes	8

Assuming that the non-operating failure rates are zero, use this data to calculate operating failure rates for each item of equipment. Hint: When doing this ensure that you consider the mission profile and total population of each item of equipment that these failures relate to. Show all your workings and assumptions.

An assembly of 2 motors with a pump and a control box is defined as a Pump Boost Unit (PBU).
What is the reliability of one PBU (RPBU) in a 16-hour operating period to 2 decimal places?
Calculate the reliability of a single pipeline (RP) in a 16 hour operating period to 2 decimal places.

Q2. In the analysis of system events known as Fault Tree Analysis what is the meaning of the term "Cut Sets" with respect to the lowest level events that are analysed. Explain the significance of the term "Minimal Cut Set".

Consider the following event tree in the figure below.

Write down the Boolean expression for the top-level event, T; in terms of the lowest level events X, Y, Z and W. Using Boolean algebra simplify the expression for T as far as you possibly can and write down this result.

What are the minimal cut sets of events for the above event tree?

If the probability of X occurring is 0.002, the probability of Y occurring is 0.04, the probability of W occurring is 0.06 and the probability of Z occurring is 0.015, what is the probability of T occurring?

An unmanned underground facility located in a low-lying area is potentially subject to flooding. To protect equipment installed in this facility a special watertight door has been installed in the main access corridor. This door's normal position is fully recessed into the corridor's ceiling as a sliding door. In the event of water entering the corridor, an electronic moisture sensor (A) initiates a door closing mechanism (B) that allows the door to close and seal by gravity. If the door fails to seal closed a small electric motor connected to mains power (C) will drive the door closed and sealed (D).

Develop a simple RPN FMECA for the door in the event the corridor floods that considers failures in A, B, C and D. Estimate some reasonable values and descriptions for these faults and calculate the RPN that this event occurs.

Q3. A manufacturer is planning to implement an Internet of Things (Industry 4.0) capability. The capability is based on 1300 devices placed in production points around the plant. The IoT devices operate 24 hours a day. There are three 8- hour shifts to provide the 24-hour a day on-site coverage

SHIFT	TIME
Daytime	8am to 4pm
Evening	4pm to 12am
Night	12am to 8am

The IoT devices have an in-service Mean Time Between Failures (MTBF) from all causes, that is equipment failure and damage, of 2000 hours for daytime and evening shifts. The MTBF for night shift is 3000 hours. They are maintained from a centrally located maintenance crib. The average time to repair a machine at its location is 1.75 hours with an additional average 1 hour for the technician to travel from the maintenance crib to the device and back to the crib.
Calculate the total man-hours required to carry out maintenance on these devices on site per annum. Show all details of your calculations and any assumptions that you make.
If you assume that each maintenance technician is available for work for 38 hours per week for 47 weeks of the year, how many maintenance technicians need to be employed?

The tools to carry out repairs are valuable and attractive; and need to be managed. How many maintenance tools kits need to be purchased?

In no more than two or three paragraphs, suggest a simple strategy to reduce the maintenance response time. Verify your answer with a calculation.

Q4. You have extensive hands-on and academic expertise in reliability skills.
Consequently, you have been invited to attend an industry advisory group that focuses on the future skill plans for industry. This is typically five (5) years from now for a subsequent 10 years to 15 years from now. That is, students who have just started post-secondary education and students have just started secondary education.
The advisory group is trying to understand the future skills that will be needed but are not yet thought of. These skills will need to be addressed in education and training of current and future generations of the work force and consumers.
To provide insight into future reliability skill requirements, draw on your collective expertise and provide short answers on the following topics.
a. What role will reliability have in the design, manufacture, selection, distribution, and support of property, plant, equipment, and products?
b. Identify three (3) factors that will drive reliability?
c. What reliability skills will be needed that are not yet identified?
d. How will these reliability skills be taught?
e. What is a critical unknown reliability issue that needs to be solved?
f. What is a critical legacy reliability issue that needs to be sustained?

M1 A mining company has a vehicle parked up (non-operational) under normal operations. It is classed as operational when there is a need for surge capability. The vehicle is in a non- operational condition for twelve weeks and then is required to be operational for tasks of eight hours duration. The vehicle non-operational failure rate is 1.5 per million hours and its operational failure rate is 2.0 per million hours. What is the probability that the vehicle is in a working condition

[A] 0.997
[B] 0.998
[C] 0.993
[D] 0.992
[E] None of the above

M2 A road condition advisory system consists of 400 units operating continuously with each one consisting of two parallel operating units A in a redundant arrangement with an operating unit B in series configuration as shown below. Each unit A has a MTBF of 25,000 hours and each unit B has a MTBF of 30,000 hours. How many unscheduled maintenance demands would you expect in the system per week, rounded to the nearest integer value.

[A] 6

[B] 11

[C] 5

[D] 8

[E] None of the above

M3. Reliability analysis of individual components and the units of which they are part often assumes that failure rate with respect to time follows the standard ‘bathtub' curve.

Which of the following items is likely to NOT have a relatively well-defined wear-out phase with its failure rate increasing with time? (one correct answer only)

[A] An electromechanical relay

[B] A home theatre amplifier

[C] A mechanical bearing

[D] A unit consisting of a wide variety of electronic, electromechanical and mechanical components

[E] None of the above

M4. A system's reliability block diagram is shown below. The values for the reliabilities of the various components are also given.

Ra = 0.8, Rb = 0.8, Rc = 0.9, Rd = 0.9, Re = 0.8, Rf = 0.7

What is the overall reliability of the system to two decimal places?

[A] 0.91

[B] 0.87

[C] 0.84

[D] 0.90

[E] None of the above

M5. Which of the following statements is fully correct? (One correct answer only)

[A] Reliability is only a function of a system's failure rate.

[B] Reliability is the probability that a system does not experience failure over a given time period.

[C] Reliability is one minus the rate per hour at which a system experiences failure.

[D] Reliability is the probability that a system does not experience failure under a stated set of environmental conditions.

[E] None of the above.

M6. When considering the reliability characteristics of hardware, software and human factors, which of the following statement is most correct?

[A] The physical environment of the equipment affects failure rates.

[B] The physical environment of the computer does not affect failure rates.

[C] The physical environment of the operator strongly affects the failure rates of the human operator.

[D] All statements are correct.

[E] Some statements are correct.

M7. A life cycle cost analysis is used to measure the reliability performance of a system. Which of the following statements is most correct when considering life cycle cost factors to model?

[A] Life cycle cost is not relevant to system optimisation.

[B] Life Cycle Cost = Acquisition + Ownership Costs

[C] Life Cycle Cost = Acquisition + Operating + Logistics Costs

[D] Life Cycle Cost = Acquisition + Sustainment Costs

[E] Life Cycle Cost = Acquisition + Operating + Support Costs

M8. When equipment fails it will need maintenance involving spares and other activities to restore the equipment to its operational state. Which of the following is the most complete description of the situation?

[A] Maintenance resource determination is not a significant factor in reliability studies.

[B] The number of spare units is determined by the repair and replacement policy.

[C] A spare unit can be considered the same as a redundant situation with a long switching time.

[D] The availability of spare parts has an influence on an item's operational availability

[E] None of the above

M9. Which one of the following statements is the most accurate?

[A] To optimise the reliability of a system out of a selection of design alternativesyou need only know the cost of the components in the alternative systems.

[B] To optimise the reliability of a system out of a limited selection of realistic design alternatives you may need to consider not only the reliability and the cost of the components in the alternative systems but possibly other engineering parameters as well.

[C] The process of engineering optimisation always involves considering the reliabilities of components in a set of alternative design solutions to the system requirements.

[D] To optimise the reliability of a real system out of a selection of design alternatives you need to know only the reliability and the cost of the components in the alternative systems.

M10. Consider the following statements. Which is the most correct statement?

[A] Backup systems almost always result in an increase in overall system reliability.

[B] Redundancy is rarely used at the component level (i.e. transistors or capacitors) in order to maximise the reliability of the unit.

[C] A dormant failure is a failure that occurs in a system that does not result in immediate system failure.

[D] Redundancy increases system design complexity because of the need to determine which of the redundant systems has failed and reliably switch between them.

[E] All statements are correct.

Attachment:- Advanced Reliability.rar