Wikipedia:Reference desk/Archives/Science/2022 January 5

= January 5 =

Finding a scheduling algorithm (project management)
Hey! I am a student of industrial engineering and as part of a project I'm working on I'm trying to minimize the number of tardy jobs in a production floor, where I have a constant number of non-identical working stations (the "machines"). My data shows that ~60% of my jobs at the current situation are tardy. In addition, Managers in the organization prioritize customers using numbers (i.e. The most preferred customer gets the score 1, followed by the second customer with the score of 2, and so on). Unfortunately, I can't pinpoint the exact scheduling method that works on non-identical m machines, and can combines the priority matter.

English is not my native language, so feel free to edit this question if the English is incorrect. Thanks! — Preceding unsigned comment added by 2A0D:6FC7:20E:B0DA:702D:566B:124B:245D (talk) 17:05, 5 January 2022 (UTC)


 * For a given job, should it be scheduled to be performed at a specific machine among the m machines, or is there some freedom of choice? Is the only difference the processing speed of the machines? Can different jobs be processed concurrently at different machines or is there at any time only one job being processed that may need several machines in some order? Optimal job scheduling and job-shop scheduling are both optimization problems with many variations, and can have a number of different objectives to serve as the objective function – minimizing the number of tardy jobs is a bit crude as not all occurrences of tardiness are equally bad, which is obvious in this case because all customers are preferred, but some are more preferred than others. You need to give a more detailed description of the concrete problem and the objective before an expert (which I am not, I'm afraid) can (hopefully) direct you to a good scheduling method. --Lambiam 23:11, 5 January 2022 (UTC)


 * Sorry, I also can't give a specific recommendation. Lambiam has suggested some good articles for reading; I would also suggest takt time. If I'm understanding you correctly, part of the problem seems to stem from there not being takt times assigned to the machines. If nothing else, that may at least help narrow down your searching. Matt Deres (talk) 21:53, 6 January 2022 (UTC)


 * Thanks for your Q's. A Job is indeed targeted for a specific machine - but I have a data base with all the Jobs and what machines can do it (can be between 1 to m) - it means that I can switch machines to my jobs if they are able to complete them. The machines differ in the type of work and not just in speed. Each machine can do only one Job at a time, and each Job need only one machine. My factory does not deal with Mass production, and each set of Jobs (an "Order" for a product) is accompanied by a Due date.  — Preceding unsigned comment added by 87.70.11.210 (talk) 17:28, 11 January 2022 (UTC)

blood oxygenation
Questions inspired by usual stories about covid patients.


 * 1) A typical symptom of covid pneumonia is that the person has very low blood oxygen (like 50% even) but is awake, talking, and in comparatively little distress.  Normally someone with such low O2 would be unconscious.  How is it that Covid patients avoid this?
 * 2) Covid treatment (besides meds) centers on getting O2 into the person through the lungs, first with supplemental O2 through the nose, then intubation, and EXMO is a last resort.  Intubation itself seems horribly drastic though. Is there a big obstacle to using EXMO sooner, i.e. is it way more drastic than something like kidney dialysis?  Is that because of the high volume of blood that it has to move to deliver enough oxygen?

Thanks. 2601:648:8202:350:0:0:0:9435 (talk) 20:32, 5 January 2022 (UTC)
 * The article about Extracorporeal membrane oxygenation (ECMO or EXMO) describes a number of side effects and complications. Philvoids (talk) 23:16, 5 January 2022 (UTC)
 * These possibly not all RS hint at another barrier besides risk/benefit to the patient i.e. resourcing (especially staff time) [//journals.lww.com/ccmjournal/Fulltext/2020/06000/Joint_Society_of_Critical_Care.9.aspx] [//www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)02137-1/fulltext] [//www.ncbi.nlm.nih.gov/pmc/articles/PMC8610487/] [//labblog.uofmhealth.org/health-tech/ecmo-offers-sickest-covid-patients-a-chance-to-survive-but-a-slimmer-one-than] [//www.frontiersin.org/articles/10.3389/fmed.2021.716086/full]. From what I can tell ECMO is more "expensive" treatment than intubation in terms of the demands on highly trained and experienced staff for initiation and monitoring. From [//www.medpagetoday.com/infectiousdisease/covid19/89562] I found [//www.ncbi.nlm.nih.gov/pmc/articles/PMC8478083/] where they call a similar strategy "ECMO first". Although it's only a single case report of a specific case where there were concerns for initiating mechanical ventilation so doesn't actually tell you anything useful about which is better but there is a list of the end of possible disadvantages of such a strategy, and perhaps searching for ECMO first will find a bit more. I did also find [//www.medpagetoday.com/infectiousdisease/covid19/90490] from the real early days which suggests even then there was great disagreement about such a strategy.  Nil Einne (talk) 05:13, 6 January 2022 (UTC)


 * Re (1): I don't know, but from Oxygen saturation (medicine):
 * "Oxygen is more readily released to the tissues (i.e., hemoglobin has a lower affinity for oxygen) when pH is decreased, body temperature is increased, arterial partial pressure of carbon dioxide (PaCO2) is increased, and 2,3-DPG levels (a byproduct of glucose metabolism also found in stored blood products) are increased."
 * Perhaps some of the body's responses to Covid-19, including fever, help to offset the effects of low blood oxygen. Is there a doctor in the house? {The poster formerly known as 87.81.230.195} 90.208.89.176 (talk) 08:18, 6 January 2022 (UTC)