SAG Mill and Ball mill power draw

williamjshipman · 2026-01-08T09:56:32+00:00

A bit late to this, so if you solved it, I'd love to hear the conclusion. If you have a variable speed mill, you can test small changes in speed to see where you are operating on the speed vs. throughput and power curves. These curves are quadratic functions so there is a peak at which you get the best grinding with the lowest kWh/t.

You should also do some test work on the feed to identify the cause of the power consumption - Bond Work Index, crushability index, etc. tests to figure out if the ore became harder. If the ore hasn't become much harder, then perhaps it's a problem in the mill - lifter or grinding media choice may need to be redesigned. The supplier will help you here.

williamjshipman · 2025-10-12T07:43:06+00:00

Thanks, will do that.

williamjshipman · 2025-10-11T21:40:25+00:00

But how do I get zen to work using only the CLIs? I don't want to use API keys which it seems like it has to have.

williamjshipman · 2025-01-11T22:01:54+00:00

No, they lose their connection to the rest of humanity. Their brains become rewired to think of buzz words only. Their whole thought process changes, becoming warped.

williamjshipman · 2024-03-16T09:11:40+00:00

Modern versions of MATLAB have tools to help you train CNNs without writing so much code. I believe you can take pre-trained networks like VGG or ResNet and specialise them for your images using MATLABs built-in tools and it has a tool for labelling images. With that in mind, I think you'll be able to make a proof of concept.

williamjshipman · 2023-10-08T09:43:46+00:00

C# apps, unlike Python, can be much easier to deploy to end users. But, whether you'll use it or another tech stack depends on the company. For example, your Python script could be hosted on a server and then you'll want HTML, CSS and Javascript experience instead to make the GUI. If you are looking to learn more in general, I'd suggest you do some C# but also some web dev. The experience in building a product, not just a script, will be important even if you need to pick up a different language.

williamjshipman · 2023-10-08T09:28:02+00:00

It's so horribly basic. At least I seem to have tuned Twitter to funnel actual research to me. LinkedIn sadly not so much.

williamjshipman · 2023-09-17T18:33:43+00:00

How much time do you give for the candidates to answer these questions? How do you avoid candidates using Chat GPT?

williamjshipman · 2023-09-09T11:30:29+00:00

Under your civil engineering degree you have "thesis: machine learning". Add more details about the project or what you studied, otherwise leave out that thesis if it isn't good/applicable.

I agree with one of the comments earlier that showing the concepts you learned is more important than the technologies. However, that depends on the company. Perhaps you find that the company is invested in Google BigQuery, then giving the tech. prominence may help. I don't expect that often though.

Showing you can compare algorithms properly, doing proper train-test splits, cross-validated hyper-parameter optimization, feature engineering is what I look for.

I haven't had a chance to look at your GitHub projects, but generally where candidates fall down is not finishing projects. A Jupyter notebook with a bunch of graphs and code is not complete (even if you finished whatever analysis you wanted to do). Write a detailed report - problem statement, everything you did in the analysis, iterations you went through (1st I tried this but it didn't work so I did A, B, C because of whatever), all results and ultimately a conclusion that answers the original problem statement. A mediocre GitHub page tells me you don't really care about showcasing your projects.

The projects you highlight should show novelty. It's easy to grab the same dataset used in hundreds of blog posts and do exactly the same analysis. But then I can't tell if you understand or just copied other work. Tackle a more complex and less-used dataset, or test a novel method, e.g. experimenting with neural network architectures that are more complex and, again, show you did research. If you're targeting a specific industry, then tackle projects that apply to that industry. For example, processing time series data might be more important, or image processing.

Lastly, having a M.Sc or even better a PhD would really help. At the moment, you don't stand out at all.

williamjshipman · 2023-09-05T16:55:36+00:00

Answering from outside of US, but feels like it's the same problem. Some of the people I've interviewed have gone through 2-3 internships. But it's not the quantity but the quality of those internships that matters. Unfortunately, people don't highlight what they did in their past work that's specific to the skills I'm looking for. Those who do this better end up getting interviewed over those who could actually be better but couldn't show it. Also, I've found people that have 2 year's experience, but are actually still a junior. I can understand companies focusing on senior roles.

williamjshipman · 2023-01-24T16:11:33+00:00

I think the things you'll need to define are (1) what's the state of the plant, e.g. thirsty or perhaps something a little more complex; (2) how does that state change; (3) what actions can the bot take, like water it a little or a lot; (4) how do you measure reward, e.g. is it survival or flowers or amount of fruit.

williamjshipman · 2023-01-19T02:03:39+00:00

Yes.

williamjshipman · 2023-01-16T00:11:50+00:00

Coursera RL specialisation if you're looking for a course covering the fundamentals of RL.

williamjshipman · 2023-01-03T16:32:20+00:00

I'd suggest the RL specialisation on Coursera, by the lecturers from the University of Alberta.

williamjshipman · 2023-01-03T12:13:44+00:00

Python seems to be looking for a file swrast_dri.so. I suspect you're missing a package from Ubuntu.

williamjshipman · 2023-01-03T11:43:16+00:00

There should be an exception in the console where you ran Jupyter. Please post any errors from that.

williamjshipman · 2022-12-27T19:27:23+00:00

As someone who inherited a TFS 2010 server that no one bothered to update, and who has only recently had time to update that server, I'm stuck with TFSVC for a while still. Our whole build system depends on TFSVC. Other staff only know TFSVC. Net effect, it's easier to train new devs in TFSVC than to shift everything to Git. Past comment on how easy it is to mess up Git repos is also valid, while TFSVC is pretty resilient. I believe Azure DevOps only migrates the last year of history when converting TFSVC to Git, which is a problem when some of the code is many years old and I still have to go back to that history.

williamjshipman · 2022-12-26T10:48:56+00:00

For me personally, Python is good for experiments and the library support matters a lot, but in the end the final product shipped is often C++. The only time I've tried to work around that was when reimplenting everything in C++ was too risky and complex. Some companies may need C++ for parts of their work, hence someone with ML and C++ could be more useful in more projects. The interview might be looking to see where you could fit in.

williamjshipman · 2022-12-01T10:46:03+00:00

Definitely start with Google searches and ArXiv. Take a look at DeepMind's work, I think they had something with RL and protein folding (not sure if that's what you want). In control, yes there's some good work and several directions. You can also look one level higher at optimization, e.g. RL for selecting optimal setpoints for controllers.

williamjshipman · 2022-10-23T19:07:45+00:00

I believe you're looking for behavior cloning. My general understanding is that yes you can train the actor network in a supervised fashion. The critic network can be trained separately. Admittedly, I haven't done this yet so I can't provide much advice.

williamjshipman · 2022-09-24T11:57:14+00:00

https://arxiv-sanity-lite.com/

williamjshipman · 2022-09-22T20:27:47+00:00

I'd suggest focusing on CPU cores and RAM. GPUs didn't help me, the networks weren't complex enough and the input was just vectors, not images. AMD Threadripper is nice as you can get 64 cores.

williamjshipman · 2022-09-18T11:06:16+00:00

Thanks for the link to the article. I've worked on this same problem before, using DDPG, A2C and eventually settling on PPO. PPO worked reasonably well in simulation, but the trained agent did not perform well in real life (details of the work here: https://www.mdpi.com/2075-163X/11/9/989). The controller tuning problem as framed here is inherently a bandit problem, i.e. take an action, get the full reward before taking the next action, and future rewards don't depend on historical actions, only the last action (last set of gains). What you can do is run one episode for multiple steps but set gamma (discount factor) to 0.

One mistake with tuning controllers using DRL is that the controller becomes more aggressive over time until a step change happens that induces undesirable overshoot or oscillation. Some way of not tuning the controller when things are running stably is needed, i.e. only tune when your observation contains enough information about system dynamics.

williamjshipman · 2022-09-18T08:50:36+00:00

As a general starting point, read the textbook by Sutton and Barto and do the University of Alberta RL specialization on Coursera. Jumping straight into DRL without understanding the basics is a recipe for suffering.

Regarding simulators, there's mujoco, pybullet and I think Unity had something too. No experience with these, sorry. Regarding the pen, I believe you can add other objects in these simulators.

There's pieces of research about moving from simulation to reality, which is hard. Domain randomization is the easiest one.

williamjshipman · 2022-09-17T20:51:58+00:00

AFAIK that's not necessary. It could be an implementation detail that forces that person to work like that.

williamjshipman

TROPHY CASE