Reference no: EM132593681

Assignment 1

Part 1

A hospital operating theatre (OPTH) has two operating tables, TAB1, and TAB2. Each table and its associated support equipment and lighting draws 2.5KW of electrical power. The mains power circuit (MAINS) to the operating theatre can provide 6KW of power. There are two backup power systems in use:

Each backup system (BACK1 and BACK2) is a self-contained photo voltaic system with an associated high capacity storage battery that can provide 4KW of electrical power. You can assume that each backup system can provide power indefinitely for the purposes of this assignment.

Q1 - Draw a reliability block diagram for the OPTH where both operating tables are required. Use minimum backup system(s) consistent with OPTH power requirements.

Q2 - Draw a reliability block diagram for the OPTH where only one operating table is required. Use minimum backup system(s) consistent with OPTH power requirements.

The estimated failure rates of the various OPTH units are as below. All units are per million operating hours.

An operation is scheduled to need one operating table. The expected duration of the operation is 2.5 hours.

Q3 - What is the probability that the patient will have to be moved to the spare operating table during the operation?

Q4 - What is the probability that the operation will be completed in this OPTH without a failure that would necessitate an emergency transfer to another OPTH?

Q5 - Can you estimate the expected number of maintenance actions for each of the 2 units Operating Table and PV Backup over a period of a year with the Unit failure rates as above. You can assume that failed items will be repaired promptly. The OPTH Duty Cycle will be 75% (18 Hours per day) Calculate separate values for the 2 scenarios described in Q1 and Q2 above.

Part 2

Your company has just been awarded a contract to design and install many remote area emergency phone (RAEP) boxes to be positioned along the outback road system in tropical Northern Australia. The equipment will consist of a simple but rugged protective hood, a phone handset, a radio transmitter/receiver unit, and a solar cell panel charging a set of four sealed batteries. Initial system engineering studies have indicated that the handset, batteries, and solar cell panel can be existing components already in use in large numbers for four years in similar phones designed and installed by your company in Tasmania which has a temperate climate.
The transmitter/receiver unit will have to be a new unit designed and manufactured by your company.

Q6 - Discuss how you would approach the task of estimating failure rates for the component units in the RAEP. Consider points such as how much confidence you might have in the validity of any likely sources of failure rate data. Please note that you are being asked to discuss the level of confidence in failure rate data that you are preparing for the RAEP with respect to where the data is likely to be coming from and whether historical data is likely to exist or not. Distinguish between estimating failure rates for components that are already in use in the Tasmanian system and the new transmitter/receiver that is new design.

Q7 - You can assume that you have access to failure reporting system data for the Tasmanian system. Discuss how you would use this source data in applying it to the RAEP. Would it be necessary to adjust this data for the different environments? Discuss any environmental factors that are likely to be different between the RAEP and the Tasmanian system.

Assignment 2
Part 1

A system is to consist of three different units A, B and C, all of which must function correctly for mission success. It is to have a minimum specified reliability of 0.90 for a mission time of 6.5 hours.

Q1 - Calculate the overall failure rate for the system based on the specified reliability for a 6.5-hour mission. A complexity analysis has been completed for each unit and the following conclusions have been reached:

Q2 - Calculate an allocated specified value of reliability for each of the three units for a mission of 6.5 hours on the assumption that the overall failure rate you have computed in Q1 above is divided up amongst each unit in direct proportion to its fraction of the total complexity.

The following versions of Units A, B and C are available

Q3 - Select the cheapest version for each of the three units such that each unit satisfies its reliability allocation as calculated in Q2 above at a minimum price. Write down the overall resulting system reliability and overall cost.

Q4 - Having done that, now select a version for each of the three units irrespective of their individual reliability allocations such that the overall system meets or exceeds the allocated system reliability of 0.90 for a 6.5-hour mission at minimum cost. Write down the version of each unit and what is now the overall system cost?

Part 2

A high-power amplifier (HPA) and its associated cooling system and temperature sensor consists of 6 Amplifier Modules, 2 Cooling Units and 2 Temperature Sensors. All units are needed for correct HPA operation.

The HPA units have the following predicted reliability, maintainability, and cost parameters:

Q5 - Compute the HPA availability where there are no spares.

Q6 - Assign several spares to raise the HPA availability to > 95% at the minimum possible spares cost. What are the spares needed, their cost and the resultant HPA availability?

Q7 - Experience in service shows that the Amplifier Module is failing with an MTBF of 12670 hours. How would you modify the spares support of the HPA to bring the HPA availability back to greater than 95% at a minimum cost?