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SCI7440 Computer Tools for Simulation
1. Background
You have just received a phone call from Dr. Ho. He is in charge of the blood donation service for Hong Kong and has heard that simulation might help in the redesign of the blood donation centre in Kowloon. He would like advice on staff and equipment changes need require for running the centre more http://www.ukassignment.org/lxszy/ efficiently. An important factor in operating the blood donation service is that donors are often busy people and, if they find they waste a lot of time when they visit a centre, it discourages them from coming again – an important loss since the service depends on having a large group of reliable donors.
The full process is as follows.
Donors may arrive at any time between 09:30 and 19:30, Mondays to Fridays. The centre is closed on weekends. Anyone arriving after 19:30 will be turned away. Donors arrive at an average rate of 20 per hour up till 14:00. Between 14:00 and 17:00, the rate is 20% lower; between 17:00 and 19:30, there is a rush of people who have just finished work and thus the arrival rate is 20% higher than it is in the morning. You may assume that all arrivals are independent of each other.
Donors first arrive at a reception desk, currently manned by a single receptionist. Data has been collected but not statistically analyzed with regard to the time it takes to collect a donor’s details. This data has been provided by Dr. Ho in an Excel file for you to decipher. You will need to determine an appropriate distribution to use (e.g., using Stat::Fit). It should be noted that donors waiting in the queue for a receptionist have a finite “shelf life.” That is, they will leave if they have been waiting too long; this is normally referred to as “balking.” The amount of time before a donor balks is thought to be about 20 minutes, but may be as little as 12 minutes for some people and up to 40 minutes maximum for others.
A donor attendant, of which there are currently 4, then performs a simple blood test. This is straightforward and takes an average of 2 minutes, with 95% of tests taking between 1.5 and 2.5 minutes. Once finished, 90% of donors will then proceed to the donation stage. For one reason or another, the remaining 10% will be found unsuitable for donating blood; half will leave directly while the other half will have a cup of tea before leaving. Of those who go to the donation stage, one in ten need to be looked after more carefully (e.g., because of their age). These people will be given priority in any queue for donation or tea and so will be served first.
The donation stage takes place at a bed. This can take anywhere between 15 and 25 minutes, with all times in this range being equally likely. Before this process starts, however, a donor attendant has to insert a needle into the donor’s arm, taking exactly 2 minutes. When the donation is complete, the attendant has to take the needle out of the donor’s arm, label the blood container and put it into refrigerated storage. This takes an average of 4 minutes, normally distributed with a standard deviation of 1 minute. Donors will remain on the bed while all of this happens. Between the insertion and removal of the needle, a donor attendant is not needed. At present there are 4 beds.
Finally, the donors have a cup of tea. The tea is served by a donor attendant and takes on average 1 minute (use your judgment about what is a reasonable distribution). http://www.ukassignment.org/lxszy/ The donor then rests and drinks the tea unattended, taking on average 10 minutes. The distribution of this time is such that the probability of finishing this process at any point in time is independent of how long the process has been going on already (i.e., it is exponential).
The day is divided into two shifts: 09:00-16:00 and 16:00-19:30. During the day shift, donor attendants are paid HK$120 per hour and receptionists HK$100 per hour, whether they are idle or busy. During the evening shift, they are paid “time and a half”, i.e., 50% above the day-time hourly rate. Donor attendants and receptions all start work at 09:00 to set up and prepare the centre before donors begin arriving. In addition, there are costs per donor associated with the donation process as shown in the following table.
Activity Cost per donor (HK$)
Reception 20
Blood test 150
Blood donation 320
Tea 10
The collection service has the following targets, the first two of which should be met by 95% of donors.
(i) Donors should wait no more than 6 minutes before being dealt with at reception.
(ii) Donors should leave the clinic within 45 minutes of arriving.
(iii) The daily cost of employing staff should be under HK$20,000 and preferably nearer HK$15,000.
Your task is to construct a computer simulation model of the current service and advise Dr. Ho on changes to the number of receptionists, donation beds and donor attendants that are needed to achieve the targets above. You should also provide a budget indicating how much the changes will cost.
Bear in mind the following points.
Precise details of each distribution are not given. In some cases, you can infer what distribution to use, in others you will have to run a trace simulation, fit data to an empirical distribution or use Stat::Fit to fit the data to a theoretical distribution.
Think very carefully about the donation process. There are three distinct stages in this process: 1) needle insertion, 2) blood donation, 3) removal of needle; the first and the last require a donor attendant. If you represent this whole process using three different work centres then how will you enforce the requirement that each bed can be occupied by only one donor?Hint: besides requiring a “donor attendant” resource at the first and third work centres, use a dummy resource called a “bed” that is required at all 3 work centres. Also, since a bed must be continuously occupied, no not put queues between these work centres.
Think carefully about what happens at the end of the day. What happens to donors who are only part of the way through the process at 19:30? Do they complete the process, go home, wait overnight? Use common sense.
If there is anything else you are unsure of, make a sensible assumption and explain it in your report.
2. Instructions
The deadline for the project is 5:00 p.m.Friday3February 2012 (UK time). You must prepare a report for Dr. . The main body of the report (the executive summary) should not exceed 6 typed pages of A4 paper (11 point font, single spacing). You should also write a more technical appendix with a maximum length of 8 pages. Details of what should be included are provided below. Do put your name on the report. Dr. will want to know who it has come from! Reports should be emailed in PDF format only to the module convenor before the deadline. Besides your report, you should also include a copy of your SIMUL8 models. Please put all of the files into a single ZIP file.
2.1 Executive summary (50%)
Describethe current operational efficiency of the blood donation centre and any changes you would recommend employing. In particular, highlight important findings you have discovered about the blood centre’s current operations that you wish to bring to Dr. Ho’s attention. Further, discuss recommendations about changes concerning thenumber of receptionists and donor attendants to employ and the number of donation beds required. You should describe the various alternative arrangements you have tried and explain why you recommendation is best. Be sure to address each of the main targets. If you believe the targets are unrealistic, then you should explain why and recommend changes to them.
Writing to your audience: Whenever you write anything, you must bear in mind your audience. It is always your responsibility to write in a style that your audience will understand. You must, therefore, think about their experience, their familiarity with technical vocabulary, the time they have available to read what you have written, etc. This is actually a difficult skill to acquire. In this project your business and technical reports are written for very different audiences. You must, therefore, make their styles different!
2.2 Technical appendix (50%)
Briefly describe the setup and flow of your model. Be sure to include a figure showing your model. You can use the print screen button on your keyboard to copy the model from SIMUL8 and then paste it into your document. In addition, annotate the figure and provide a “walk-through” of the model so that it is clear what is happening at each step of the whole process. Highlight any special features of your model.
Give a brief description of which distributions you chose and why. Think about summarizing this in a table. A good report should also include a brief analysis of how sensitive your results are to the distributions you have chosen, especially for times at the reception area.
How did you set-up and run your simulations? For example, what did you choose as the total run time for your model? How many trials did you perform for each experiment? Give a brief justification.
Discuss some of the key assumptions and or limitations of your model. What does your model unrealistically impose or fail to consider that occurs in the real-world? How might this be affecting your results?
The main focus of the technical appendix should be on running experiments and analyzing results. A good report should contain a number of tables and or figures summarising your results, a thorough analysis and a discussion of key findings. Be sure to include confidence intervals on any reported results!#p#分页标题#e#
Please note: This assignment does not consist of precisely defined questions that you must answer. Broad guidelines are given but you may develop your analysis as you think best.
2.3 Marking criteria
A good project should show that you have achieved the objectives of the module. Projects will be marked accordingly. Thus, there will be marks for developing an appropriate simulation model, analysing the model and communicating the outcome of that model to non-specialist and specialist audiences. Standard KBS categorical marking criteria for coursework essays and narrative assignments will be applied (see following pages).
Plagiarism
Reports should be written individually. The submitted report must be completely in your own words. Do not be tempted to work with another student on this project or to copy someone else’s work. This is quite easy to spot and will receive a failing grade in addition to any disciplinary action you may receive from HKBU or the University of Kent. Also, anything you obtain elsewhere (e.g., the internet, journals, software manuals, etc.) must not be cut and pasted into your report and presented as if it was your own work. You may use such material, but it must be properly referenced.
J.R. O’Hanley
November 2011
Generic level M grade assessment criteria
Mark Knowledge & understanding Analysis and application Transferable skills
80+ - A systematic understanding of an excellent factual and knowledge base.
- An exceptional ability to interpret current issues in the context of emerging knowledge in the discipline. - Comprehensive and wide ranging understanding of applicable and relevant techniques.
- Highly original application of knowledge and techniques to evaluate and develop research and enquiry in the discipline. - An exceptional ability to communicate discipline specific content to a wide range of audiences in a highly comprehensible manner.
- An exceptional ability to act autonomously in planning and directing tasks at a professional or equivalent level.
- An excellent ability to undertake appropriate activities to advance knowledge, understanding and skills at a professional level.
70-79 - A comprehensive understanding of a very good factual and knowledge base.
- A very good ability to interpret current issues in the context of emerging knowledge in the discipline. - A very broad understanding of applicable and relevant techniques.
- Very good original application of knowledge and techniques to evaluate and develop research and enquiry in the discipline. - A very good ability to communicate discipline specific content to a wide range of audiences in a comprehensible manner.
- A very good ability to act autonomously in planning and directing tasks at a professional or equivalent level.
- A very good ability to undertake appropriate activities to advance knowledge, understanding and skills at a professional level.
60-69 - A good understanding of an good factual and knowledge base.
- A good ability to interpret current issues in the context of emerging knowledge in the discipline. - A broad understanding of applicable and relevant techniques.
- Good original application of knowledge and techniques to evaluate and develop research and enquiry in the discipline. - A good ability to communicate discipline specific content to a wide range of audiences in a comprehensible manner.
- A good ability to act autonomously in planning and directing tasks at a professional or equivalent level.
- A good ability to undertake appropriate activities to advance knowledge, understanding and skills at a professional level.
50-59 - A fair understanding of a reasonable factual and knowledge base.
- A fair ability to interpret current issues in the context of emerging knowledge in the discipline. - A fair understanding of applicable and relevant techniques.
- Some originality in the application of knowledge and techniques to evaluate and develop research and enquiry in the discipline. - A fair ability to communicate discipline specific content to a wide range of audiences in a comprehensible manner.
- A fair ability to act autonomously in planning and directing tasks at a professional or equivalent level.
- A fair ability to undertake appropriate activities to advance knowledge, understanding and skills at a professional level.
40-49- - A limited understanding of a narrow factual and knowledge base.
- A limited ability to interpret current issues in the context of emerging knowledge in the discipline. - A limited understanding of applicable and relevant techniques.
- Limited originality in the application of knowledge and techniques to evaluate and develop research and enquiry in the discipline. - A limited ability to communicate discipline specific content to a range of audiences in a comprehensible manner.
- A limited ability to act autonomously in planning and directing tasks at a professional or equivalent level.
- A limited ability to undertake appropriate activities to advance knowledge, understanding and skills at a professional level.
30-39 - A very limited understanding of a narrow factual and knowledge base.
- A very limited ability to interpret current issues in the context of emerging knowledge in the discipline. - A very limited understanding of applicable and relevant techniques.
- Little originality in the application of knowledge and techniques to evaluate and develop research and enquiry in the discipline. - A very limited ability to communicate discipline specific content to an audience in a comprehensible manner.
- A very limited http://www.ukassignment.org/lxszy/ ability to act autonomously in planning and directing tasks at a professional or equivalent level.
- A very limited ability to undertake appropriate activities to advance knowledge, understanding and skills at a professional level.
0-29 - A very poor understanding of a narrow factual and knowledge base.
- A very poor ability to interpret current issues in the context of emerging knowledge in the discipline. - A very poor understanding of applicable and relevant techniques.
- Very little originality in the application of knowledge and techniques to evaluate and develop research and enquiry in the discipline. - A very poor ability to communicate discipline specific content to an audience in a comprehensible manner.
- A very poor ability to act autonomously in planning and directing tasks at a professional or equivalent level.
- A very poor ability to undertake appropriate activities to advance knowledge, understanding and skills at a professional level.
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