ENG1060 ASSIGNMENT – S1 2021
Due: 11:55PM, Friday 21st May 2020 (Week 11)
Late submissions: A 10% penalty (-1 mark) per day, or part thereof, will be applied. No
submissions will be accepted once the penalty has reached 50%.
GUIDELINES
This assignment is to be completed INDIVIDUALLY. Students are advised to review Monash
University's policies on academic integrity, plagiarism and collusion. Plagiarism occurs when
you fail to acknowledge that the ideas or work of others are being used. Collusion occurs
when you work in a manner not authorised by the teaching staff. Do not share your code or
code with others. You may discuss ideas with your peers but the approach to coding must be
your own. You must have full understanding of it.
All assignments will be checked using the Measure of Software Similarity (MOSS) plagiarism
and collusion detection software. Files with high similarity counts will be flagged and
reviewed. In the event of suspected misconduct, the case will be reported to the Chief
Examiner and the student's unit total will be withheld until the case has been reviewed and a
decision has been finalised by the Associate Dean of Education (Engineering).
INSTRUCTIONS
Download the assignment template files from Moodle and modify the code within the
template files (e.g. Q1a.m, Q1b.m, etc.). DO NOT rename the template m-files OR modify
run_all.m. Check your solutions by running run_all.m and ensuring all questions are
answered as required. Do not use close all, clear all, clc in any m-files except run_all.m. The
variables must remain in the workspace upon each file call.
This assignment assesses your ability to apply concepts taught in ENG1060. Therefore, do not
use any toolboxes or functions that are not taught in ENG1060, unless otherwise specified.
SUBMITTING YOUR ASSIGNMENT
Submit your assignment online using Moodle. Read the “Assignment upload
instructions.pdf” to prepare your ZIP file for submission. Your ZIP file (not .rar or any other
format) must include the following attachments:
a. Solution m-files for assignment tasks (e.g. run_all, Q1a.m, Q1b.m, etc.)
b. Any additional function files required by your m-files (e.g. comp_trap.m,
heun.m, newraph.m, etc.)
c. All data files needed to run the code including the input data provided to you
(e.g. data1.txt, data2.csv, etc.)
Your assignment will be marked in your usual computer lab session during Week 12. You must
attend and be present for the assessment to be marked. You will receive a score of 0 if you
are absent. Your zip file will be downloaded from Moodle and only these files will be marked.
We will extract (unzip) your ZIP file and mark you based on the output of run_all.m. It is your
responsibility to ensure that everything needed to run your solution is included in your ZIP
file. The assignment will not be downloaded to your individual laptops for marking.
MARKING SCHEME
This assignment is worth 10% (1 Mark = 1%) of the unit mark. Your assignment will be graded
using the following criteria:
i. run_all.m produces results automatically (additional user interaction only if asked
explicitly)
ii. Your code produces correct results (printed values, plots, etc…) and is well written.
iii. Poor programming practice will result in a loss of up to 2 marks out of 10.
iv. Your ability to answer the demonstrator's questions that test your understanding of the
assignment questions and the submitted code.
v. This assignment assesses your ability to apply concepts taught in ENG1060. Therefore, do
not use any toolboxes or functions that are not taught in ENG1060, unless otherwise
specified.
ASSIGNMENT HELP
- You may use the function files that you have written in the labs and workshops.
- You may ask questions in the Discussion Board on Moodle; in some cases, we may ask you
to submit a question to the discussion board, so that the entire class can see the answer
we give. - The m-file templates contain pre-written comments and sections only as a guide. You do
not need to follow its structure. You may delete the comments. - Hints may also be provided during workshops.
- Bold text has been used to emphasize important aspects of each task. This does not mean
that you should ignore all other text. - The task have been split into sub-questions. It is important to understand how each subquestion
contributes to the whole, but each sub-question is effectively a stand-alone task
that does part of the problem. Each can be tackled individually. - It is recommended that you break down each sub-question into smaller parts too and
figure out what needs to be done step-by-step. Then you can begin to put things together
again to complete the whole. - Solve the question, of part thereof, by hand before attempting to code the solution.
- You may discuss ideas and approaches with peers and demonstrators. However,
discussions that lead to similarity in code may result in collusion.
Assignment: Working an auriferous creek in the Golden Triangle
You are prospecting on a lovely little creek in the Golden Triangle of Victoria and find a
number of promising places to start digging for gold. Figure 1 shows the layout of the area
that you are prospecting, with the water flow direction and approximate speed indicated by
the directions of the arrows and their lengths respectively. Blue is water, brown is land and
the other features are points of particular interest, described as follows.
Figure 1: The map of the creek that you are prospecting. Land is in brown, water is in blue, rocks are
in black and arrows indicate approximate water flow direction and speed (speed is represented by
arrow length. Each deposit you might like to dig and process through your sluice is numbered and
described in the text. Sites 1, 2 and 3 are numbered.
You wish to optimise your time so you can gather the largest amount of gold in the time you
have available. You have brought your shovel (1 shovel load = 3 litres of dirt), a large bucket
(18 litre capacity) and a river sluice (your gold capturing device that retains gold while ejecting
other worthless materials). You will need to work carefully to make sure that your final
strategy will yield you the most gold in the time you have.
It is now 10am and you have to start packing up at 2:30pm to get back in time for a nice dinner
on your weekend away. You need to eat your lunch at some stage too (30 mins) so in total,
you have 4 hours to get as much gold as you can.
The sluice itself cannot take material as quickly as you can shovel it in there; it needs to clear
properly to work effectively. Below is a table of the sluice’s efficiency at gold capture as a
function of feed rate in units of heaped shovel loads (3 litres of dirt) per minute.
Table 1: Sluice gold recovery rates as a function of feed speed. Note that 6 heaped shovel loads
completely fills your large bucket and 1 heaped shovel = 3 L of dirt. Reproduced in
“Sluice_efficiency.csv”.
Standard shovel loads (3L)
per minute
Gold recovery of the
sluice (%)
1.0 95
1.5 94
2.0 92
2.5 87
3.0 78
3.5 65
4.0 51
4.5 32
5.0 24
5.5 14
6.0 7
6.5 4
7.0 3
Site 1: The first spot that you find (marked 1 on the map in Figure 1) is a hard-packed gravel
bench deposit on an inside bend of the creek that was laid down in a recent storm when the
creek flooded and water flow was very high. Gold gets trapped very rigidly in hard-packed
gravels and this looks like a good spot to dig.
The first problem is that hard-packed deposits are very hard to dig and you won’t be able to
move as much dirt compared to digging looser material. You will need to fetch your pick from
the car to actually move significant quantities - expect to subtract 40 minutes in total from
your prospecting time if you decide to dig in this spot as you will need to hike back to the car
to fetch the pick. Note also that when you need to loosen the material first with a pick, you
end up slowing your actual digging rate considerably. Normally with loose material, you could
dig at the rate of 1 heaped shovel load every 6 seconds. Using your pick to loosen the material
first reduces your effective digging rate to 1 heaped shovel load every 30 seconds. The other
alternative of course is to try and shovel dirt from this deposit without a pick and this slows
you down to about 1 heaped shovel load every 60 seconds.
The other problem is that the water flow speed near this location is not fast enough to set up
your sluice. You need to set it up 20 metres further downstream. This will force you to fill up
the 18 litre bucket you have brought with you. You are limited to 6 heaped shovel loads per
bucket (18 litres). Your wading speed can be assumed to be 1 m.s
-1
. This will be the same
whether you are travelling with a full bucket and with the current, or an empty bucket and
against the current.
You have done some test panning of deposit 1 using just your shovel (it was tough going
without that pick) and find that the gold is there in quite high concentration and stays fairly
consistent with depth as tabulated below. You can assume that this deposit is so large that it
would take many days to exhaust this deposit.
Table 2: Depth profile of gold recovered from test pans taken at location 1. Bedrock is reached at
60 cm depth, preventing further digging. Reproduced in “Site1_depth_profile.csv”.
Heaped shovel load # Depth from surface (cm) Weight of gold (g/shovel)
1 7 0.009
2 15 0.010
3 22 0.008
4 30 0.009
5 37 0.011
6 45 0.010
7 52 0.008
8 60 0.012
The only trick to remember here is that once you have dug down to the bedrock at 60 cm
depth, you can’t just keep digging at the lowest level along the bedrock because you will need
to widen your hole to get to that level. This is equivalent to sinking another hole adjacent to
the first one.
Site 2:
The second spot that you find (2 on the map) is a low-pressure system behind a large boulder
in the middle of the creek that is obstructing the main flow of water. The deposit in the
shadow of the boulder is loose gravel and sand that is easy to dig but it is under water,
meaning that your shovel loads are not going to be as large as at deposit 1 because of the
continuous water flow over and around the shovel as you bring up its contents. Digging is
therefore at a rate equivalent to about 4 heaped shovel loads per minute.
The bonus of this spot is a pick would be of no use at all here. This spot is also only 10 metres
(on average) from the sluice but you will still need to fill a bucket with about 18 litres of dirt
and take it to the sluice as it is too far to shovel the dirt directly into the sluice. Wading to
and from the sluice is again restricted to 1 ms-1 each way.
Again, test panning showed fairly good gold concentrations as tabulated below but beware
that there is no depth information here because each time you dig, the hole gets filled in
because of the water flow. You are relegated to assuming that the gold concentration will
not change much as a function of depth. HOWEVER, as the table shows, getting closer to the
boulder (further from the sluice), the gold concentration increases considerably whilst it
peters out with increasing distance from the boulder. You need to factor the amount of
wading from each location into the time taken to process the dirt. The deposit is also much
smaller than that at location 1 and is not inexhaustible. The table also estimates how many
heaped shovel loads are at each location along this deposit. Remember that a heaped shovel
load is equivalent to 3 litres of dirt.
Table 3: Position profile of gold recovered from test pans taken at location 2. Reproduced in
“Site2_position_profile.csv”.
Distance from
sluice (m)
Gold weight (g) Size of deposit in
heaped shovel loads
14 0.0040 17
13 0.0033 25
12 0.0024 32
11 0.0019 30
10 0.0013 29
9 0.0009 27
8 0.0006 22
7 0.0003 17
6 0.0002 10
Site 3: The third spot that you find (3 on the map) is another flood deposit but this time it is
entirely loosely packed. A pick is not needed here and the holes you dig will not fill themselves
in. Because the deposit consists of loose material, the gold is heavily stratified as is clear from
your test panning as a function of depth.
Table 4: Depth profile of gold recovered from test pans taken at location 3. Bedrock is reached at
90 cm depth, preventing further digging. Reproduced in “Site3_depth_profile.csv”.
Heaped shovel load # Depth from surface (cm) Weight of gold (g/shovel)
1 7 0.00000
2 15 0.00001
3 22 0.00002
4 30 0.00001
5 37 0.00002
6 45 0.00004
7 52 0.00009
8 60 0.00018
9 67 0.00042
10 75 0.00099
11 83 0.00142
12 90 0.00498
You can assume that the variation as a function of horizontal position is negligible and that
there is more than enough material to dig at the one location (enough for many days). The
location is right next to the sluice so there is no need to move back and forth with a bucket –
you can shovel directly into the sluice. You can dig at your maximum rate of 1 heaped shovel
load every 6 seconds.
Like at location 1, the only trick to remember here is that once you have dug down to the
bedrock, you can’t just keep digging at the lowest level along the bedrock. You will need to
widen your hole to get to that level.
YOUR ASSIGNMENT:
Given all of the constraints and information presented above for your day of prospecting,
your aim is to maximise the amount of gold obtained with the options given to you. To
assist you with this, you will be guided through each of the steps in concluding a plan of
action in order to maximise your gold take!
QUESTION 0 (0.25 marks)
The Sluice
(a) Import the appropriate data and plot the recovery rate of the sluice (%) as a function of
feed rate. Fit an appropriate function to the data in the plot of part 1. Show both the
original data and the fitted plot in Figure 1. (0.25 marks)
This is fundamental information as all strategies that might be employed will invariably
involve the sluice. Questions 1, 2 and 3 are independent of each other and can be solved
separately.
QUESTION 1 (3.75 marks):
Deposit 1
(a) Plot the weight of gold (g) per shovel load as a function of depth at deposit 1. Fit an
appropriate function to the data, showing this in Figure 2. According to your
assessment so far, is there a depth at which the gold concentration is a maximum?
(0.25 marks)
(b) Given your constant digging rate, plot a graph (Figure 3) of gold mass collected in your
bucket vs total digging time, showing each of these strategies on the same axes.
i. Dig only the surface and put every shovel in the bucket.
ii. Dig straight down to bedrock and put every shovel in the bucket.
iii. Dig to a particular depth, and only place shovel loads from that depth into your bucket
(one plot for each depth).
Determine the long-term average gold content of a full bucket using each of these
strategies and the average number of shovel-loads taken to fill it (including those you
wish to discard in your strategy). (1.5 marks)
(c) Having investigated the best ways to dig this deposit, you should now work out the
maximum amount of gold that you could extract in the time available by working this
deposit alone. To work this out, you need to consider what your optimal sluice feed
rate will be. This is not just about recovery rates though. Remember that the faster
you feed the sluice, the more time you will have to dig the deposit but the lower your
recovery will be. In addition to this, getting the pick from the car to speed up your
digging may also mean a greater proportion of your time taken up by sluicing and in
transit between the sluice and the deposit as it will take much less time to fill your
bucket. This is essentially a multi-component optimisation problem so you will need to
break this assessment down into the following steps:
i. Taking everything into account that is relevant, write sets of equations that describe
all of the contributions to your ultimate gold recovery as a function of time. You will
also need to use the function you fitted to the sluice recovery rate as a function of
feed rate. Include these equations in your script as anonymous functions (or
functions in separate files if necessary). You will also need to use the function you
fitted to the sluice recovery rate as a function of feed rate. (1 mark)
ii. Cast all of the relevant equations into a root-finding problem in order to optimise the
final gold take from this deposit given all of the constraints. (1 mark)
iii. Write a final equation for the optimal gold recovery per unit time using the answers
to (i) and (ii) and integrate it over the time that is available to you to get a final
weight of gold taken if you were to only work deposit 1. (0.5 marks)
QUESTION 2: (3 marks)
Deposit 2
(a) Plot the weight of gold (g) per bucket load as a function of position at deposit 2. Fit an
appropriate function to the data. On a second subplot, plot the number of bucket loads
of gold-bearing dirt as a function of position at deposit 2. This is important as the
deposit is limited in its extent and resources. Fit an appropriate function to this data as
well (0.5 marks)
(b) Work out the optimal strategy for working deposit 2 only by:
i. Factoring in the transit time to and from the sluice and the time spent at the sluice,
write a canonical set of equations that would describe all relevant aspects of
extracting the gold from deposit 2, as functions of time. Include these equations in
your script as anonymous functions (or functions in separate files if necessary).
(1 mark)
ii. Cast all of the relevant equations into a root-finding problem in order to optimise the
final gold take from this deposit given all of the constraints. (1 mark)
iii. Determine the final equation for the optimal gold recovery per unit time using the
answers to (i) and (ii) and integrate it over the time that is available to you to get a
final weight of gold taken if you were to only work deposit 2 (0.5 marks)
QUESTION 3: (3 marks)
Deposit 3
(a) Plot the weight of gold (g) per shovel load as a function of depth at deposit 3. Fit an
appropriate function to the data. On a second subplot, make an appropriate set of
graphs that allows each of the following strategies to be compared. (0.5 marks)
i. Dig straight down to bedrock and put every shovel load through the sluice.
ii. Dig to a particular depth and only feed the sluice with shovel loads from that depth
(one plot for each depth).
Given a constant digging rate, and treating the sluice feed rate as also being constant, which
of the following scenarios is going to be the best strategy?
(b) Having made a decision as to how to dig this deposit, you need to work out the
maximum amount of gold that you could extract in the time available by working this
deposit alone. To work this out, you need to consider what your optimal sluice feed
rate will be. This is not just about recovery rates though. Remember that the faster
you feed the sluice, the more dirt you are able to dig but the lower your recovery rate
will be. What you need to do is:
i. Taking everything into account that is relevant, write sets of equations that describe
all of the contributions to your ultimate gold recovery as a function of time at this
deposit. Include these equations in your script as anonymous functions (or functions
in separate files if necessary).
ii. Cast all of the relevant equations into a root-finding problem in order to optimise
the final gold take from this deposit given all of the constraints. (1 mark)
iii. Write a final equation for the optimal gold recovery per unit time using the answers
to (i) and (ii) and integrate it over the time that is available to you to get a final
weight of gold taken if you were to only work deposit 3. (0.5 marks)
QUESTION 4: (1 mark)
THIS IS AN OPTIONAL QUESTION TO GIVE YOU A CHANCE AT EXTRA MARKS
With your optimal scenarios for each of the deposits, cast all of these scenarios into a
canonical root finding optimisation problem and work out what your optimum gold yield
would be for the day in grams after integrating over the time available.
Describe (narrate) the proceedings for the day.
Given that the current gold price is $2276.50 per ounce (31.1 grams), what is the monetary
value of the gold that you took away with you this day? What hourly rate does this work out
to? If you were to do this for 40 hours a week as a full-time occupation, how much money
would you make in a year assuming the same rate that you got in these 4 hours? Given that
there is no gold tax, is this an attractive job alternative?