Good morning Hank, it's Tuesday. So lately my books, especially looking for Alaska and turtles all the way down, have been removed from libraries and schools in the U.S. due to their purported obscenity. I've talked about book betting before, and I don't want to talk about it directly today. Instead, I want to talk about what I think books do and why I write them. So half my life ago, I worked as a student chaplain at a children's hospital, and while there, I saw much of what I consider obscene. I saw children die. I saw parents terrified not just about whether their kids would survive emergency surgery, but also about how they would ever pay for the accompanying medical bills. I saw things I don't care to repeat. All of it obscene. But the fact that I was a chaplain often surprises people who are familiar with me or my work. I think it surprises many evangelical Christians because they don't understand why a fellow Christian would intentionally pollute the minds of young people with books that include premarital sex and alcohol abuse. And of course, it also surprises many people who aren't religious because they're like, why would a seemingly thoughtful person believe that every Sunday all around the world bad wine suddenly turns into God's blood? Now, I don't generally talk much about my personal beliefs online because, you know, this is the internet and I don't want to. But I continue to find religion a helpful approach to the ancient conversation about how to live as a person in a world full of other people. That said, one of the first things I learned as a chaplain is that it's not about me and it's definitely not about my beliefs, right? Because like if somebody drowning in an ocean of grief said to me that their loved one had no afterlife, it was not my job to question that. And if somebody told me that their loved one was now in heaven, it wasn't my job to question that either. My job was to listen, to really listen. I wasn't there to solve or fix their pain, which could not be solved or fixed. I was there to hear their pain and acknowledge it. As my supervisor often told me, don't just do something, stand there. And that is what I have tried to do with my work. I have tried to write books that don't just do something, they stand there. I believe that by just standing there without judgment, stories can proclaim the full humanity of their characters and in doing so can help us to see the humanity within ourselves. But just as importantly, stories also invite us into other lives. They help each of us to understand the richness and complexity of people who aren't like us. And in that sense, I kind of understand book banning because I think books are a threat to many contemporary power structures, because many of those power structures want us to see other people, especially marginalized people, whether they're marginalized because of race or sexuality or gender identity or mental illness or whatever, power structures want us to see those people as less than fully human. And so I would argue that if great books have an agenda, it is not a liberal agenda or a gay agenda or a Christian agenda, it is a humanizing agenda, a mission to recognize and acknowledge the human value in ourselves and others. So Hank, in my faith tradition, we are called in the gospel of Matthew, not just to treat our friends or our neighbors as we ourselves would want to be treated or to treat people with similar value systems as we ourselves would want to be treated. We are called to treat all others as we would want to be treated. To me, that does not mean deciding on someone else's behalf what books they should be allowed to read, nor does it mean hiding from high school students the realities of the human condition, both sexual and otherwise. To me, what it means is working to make space so that others, all others, can be treated both by individuals and by society with the same rights, dignity, and respect that I would want for me or for my family. And I think efforts to restrict stories are often efforts to restrict empathy. That's not in keeping with my faith, but more importantly, I don't think it's in keeping with a functioning society. Hank, I'll see you on Friday.


Dwi'n meddwl, yn Llyfrgelliannol Cymru, mae gennym i bydd cyfosigfaen o'ch cyffredin iawn, ac rwy'n meddwl o'r teis newlydiadau widthiaeth i mewn rhain, dwy méfyrdd yn i ysgrifennu cyntaf, atio atoges o gweithio i weld. Rwydd, dda i'n cael gwaith. Dda i'n gwaith, rydyn ni'n gallu byddiwch. Rydyn ni'n ôl i gael dw i'n fynd i bobl oeddwn i gael y flwyddyn, ac ti'n gweithio i mewn o gyflusio'n gweithio'n gwerthio'n gweithio'n gweithio. Maenai, ddyn nhw, mae Fawkes Fawkes Polo, 20 yw'r argynwys yn ddwy'r ceisio'r ddyn nhw, ddyn nhw, yn ymddangos, yn gwych gyda'r chylaid. Mae'r glasiwch, ddyn nhw, yn y 1960, yn Y Herald 948, yn ysgwyllt y ddyn nhw'n gyflawn i'r gweithio yng Nghyrru. Felly bydda'r cyfan yn gweithio'r ddyn nhw. Mae'n ddod am ychydig fod yw ddyn nhw'n gweithio. mae i�� o bod y gyd yn dweud, mae gennych, mae gennat i ôl yn gyllid, a fy sy'n ystod i fy modr pan fydd yn ôl, iddyn nhw'n gwybod hynny, maes rai iddo, mae hynny iddyn nhw'n mynd i. Ond dros gyfaint y gyrfa, rydyn nhw'n gweld bod hi fynd i fyddech chi mwy fydd yn digwyddio o'r embrys o bobl o gyrfa yn cyllid, ac yndyny, y gyrfa llwyddau o wneud y clywed yn y motoru. Mae'n ddigonol i gennych cael ei ddeud.  Mae'n intech i chi ddwyf yn eitem wyrstellung i'r cyfrifig almighty, Give ddwyf yn fwypt gael y llyfrig plannol, felly maen o ran mewn eitem, mae'n ddigonol i fi fyddwch. Yr hyn yn fwyaf cyfrifio'r cyfrifio y industry yn ddiwedd yn cael ei gŷn o'r 100 ysgol, a gwneud yn cerdd y gweithio'r bagachol yn y gweithio. Yn y gweithio eich cyfrifio eich cyfrifio o'r geniwyn llywyr, rywbeth cyfrifio'r ymddir ymlaen. Yn yw'r cyfrifio eich cyfrifio... ...nydd yw? Yn y cerdd y cyfrifio eich cyfrifio 40 yw'r cyfrifio, yw'r cyfrifio'r cyfrifio. Yi cyfrifio eich cyfrifio eich cyfrifio it will carry four people at motorway speeds all day. It won't use much fuel, most cars nowadays are in the 50 to 60 miles a gallon. I'm afraid I don't know what that is in liters per 100 kilometers, but they don't use much fuel. It won't rust, it will last a long time. Its metallurgy and rust protection is fantastic. Its oil with synthetic oils in the engine. You're engine just doesn't wear out. Now if any of you have owned Classic cars or any of you started arriving career decades ago, that isn't the case when I started driving, which is nearly over 30 years go now, cars rusted. You know, we had if you had a 10 year old car, or car over 100,000 miles, in a lot of cases you are doing quite well because you had 20, 50 multigrade oil and what passed for steel sydd wedi cael ei ddweud yr ydych chi'n gweithio'r peidio yng Nghymru, felly mae'n cael ei ddweud sy'n cael ei ddweud y 5-yrddion ymlaen gyda'r gweithio yn y oblyg. Rwy'n meddwl ychydig ar gyfrifau gyda'r gweithio'r sef, a'i nhw'n gweithio'r gweithio'r gweithio ar gyfer cyfle. Rydyn ni'n gweithio'r gweithio ar gweithio, boi'n gweithio'r gweithio'r gweithio ar gyfer gyfrifau gyda'r gweithio. Felly, mae'n gweithio'n dweud, y cas i'r cair yn ni'n gweithio, dda i'r cyflogion, mae'n gweithio. Ond ydy rydyn ni'n gweithio eich gweithio? Rydyn ni'n gweithio y ffion iawn y Fiat 127. mae'n gweithio bai'r cyflogion oedd. Mae'n gweithio'n gweithio, maen nhw'n gweithio'r car a'r cair ar y cwrnod. Mae'n gweithio'n gweithio yma mae'n gweithio i'r gweithio, y frontwheel drive a'r gearbox ar y gyrdd yma. Mae'r rhai olyw, fel y Citroen Traxion Avent ar y 30-rhyw, y frontwheel drive a'r gyrdd yma. Mae'r ffans yn ymdw i'n fwy o'r gyrdd. Mae'n ddim yn ystod, ond Alakiss Agonis yn y gearbox yn y gyrdd yma a'r oil yn y gyrdd. Y Ffiat 127 o'r posibl yw'r hynny'n ddim yn ychenty ar y dyfod yw'r ffordd. Mae'r ffordd, ond ychynig yw'r ffordd modern. Mae'r gyrdd yma ar y gyrdd yma, yw'r frontwheel drive ar y gyrdd yma, yw'r ffordd modern. Mae'r Ffiat 127 o'r rhai olyw, ond mae'r ffordd yw'r cyffredinol. Mae'r ffordd yn ymdw i'r ffordd. Y Ffiat 127 o'r ffordd, mae'n gweithio i'r ffordd. Mae'n gweithio i'r ffordd ffyrdd. Felly ychydig, mae'r Ffiat Ddechrau Gwoesi Gweithio, oedd hynny'n gweithio i'r ffordd o'r sonion. Mae'n gweithio i'r ffordd. Mae'n gweithio i'r Fesoedd Gweithio, yn gwybod造 yn 1970 er хорошо yna, oedd yna bod y ddechrau a oedd yn gweithio. Mae'r ffordd o Westminster o'r rhai o'r rhai o'r rhai. Nid yw'r ffordd. Wrth ffrws, mae'r ffordd newydd o'r ffordd, mae'r Ffiat Panda. Mae'r ffordd yw'r ffordd o'r Ffiat Panda, y bod eich bod mae'r cwelch yn cyfry ag ystod. Mae'r cyfry ag ystod, mae'r gwybod bywyr hefyd. Mae'r gweldtiau a llïddau plasig. Mae'r cwelch yn cyfry ag ystod, mae'r cyfry ag ystod, mae'r cwelch yn cyfry ag ystod, mae'r gwybod. Mae'r gwybod i'r cyfry ag ystod. Mae'r gwybod i'r ffraith o'r lefadau, mae'r cyfry ag ystod yn vehwyr, a mae'r gweithio hefyd mae ffin yn gweldwyr gweithio hefyd. Mae'r rhaglau amall yn y 70s wedi bod yn ystod oesol. I flwyddyn sydd ei f grouping arno gyda'r rhaglau sy'n gair glwn o'r llas a gweithio'r sall. A phwyl yn ddi, a ond ti wedi credu'r rhaglau wna'r rhaglau. Y meddwl yn gallu ddwybod, y methalergyd, y mhi-io. Mae'n ddiddordeb mesurau ar geyrd o็r. Ymgyrchu, rwy'n gweithio y ddechrau, rwy'n gweithio ar y cyflawn i adeutau Aldi dechrau. Mae'r adeutau Aldi, ac y ddweud â'r adeutau, mae'r ddechrau Cymraeg haf ystafell yn Monaco, a dweud y cyflawn i'r ddechrau sy'n gallu'n ddweud y cyflawn. A'r ddweud y cyflawn i'r ddweud a'r ddweud yn ddefnyddio'r ddweud, ac y ddweud yn gweithio'n ddechrau, ac y cyflawn yn ddechrau. A'r ddweud y dyfodol yn gweithio, yn y 80s, mae'r If cars are so good, why have they got baggage? Why are they all so bad?  This is a Triumph Herald 948 from 1959. This isn't my car, but I drove one of these for about 25, 30 years. My car is, as I say, with my friend's son at the moment. He's really enjoying it. This is a very old-fashioned car. This is one of the last British cars made with a separate chassis. The point with this car is it's horribly unreliable. All sorts of things break, it rusts. But the flip side of that is there is nothing on that car. Even nowadays, there aren't many parts on that car that cost more than 100 euros. Most parts cost 10 euros. You can repair that car in almost anything with a very simple set of spanners and screwdrivers. There's almost no part of a Triumph Herald I haven't taken to pieces. On one respect, this is a very bad car. But on another respect, it's a very good car because you can keep them running for 60 years with minimal effort. I know because I've done it. Let's move forward. I've put 1983 there. That's 1992. I am so bad. That is a Volkswagen Polo 6M. It's basically they had the Golf Mark 1, then the Golf Mark 2. Then the new Golf Mark 3 was a much lardier platform, so they renamed the Golf Platform the Polo and kept on making it. This is a car from the early 90s. It has some characteristics in common with the Herald. It's actually quite possible as a geek to repair one of these in your garage. There are a lot of electronics in there but there's nothing too difficult to deal with. It's got a catalytic converter. It's got electronic ignition. It's got oxygen sensors and stuff like that. But if you're prepared to learn about how those work, you can fix this car. This is a Focus C-Max. It's actually the first car of shiny where I haven't actually owned one or driven one. I use this one because my friend has one. It's a people carrier from the mid 2000s. I always remember the first time I sat in it. It was the first time I'd sat in a car where the experience of turning the car was of it booting up. This thing, at least I don't know if this one here, but my friend's Focus C-Max. The whole thing in front was a TFT and you literally got a logo, a boot logo. I strongly suspect if you delved in behind you'd probably have a Linux prompt. When she had it, it was actually a little old, so everything was starting breaking. Everything was all in one computer. To be honest, for a repairability point of view and a complexity point of view, this thing is not repairable. You will see 60-year-old triumph heralds around. You will probably, at the moment, see 35-year-olds, Fox, Vag and Golf Mark IIs, and Polo 6Ns around. I'd be very surprised if you see any Focus C-Maxes more than 15 or 20 years old. There'll always be somebody who has one, but they've managed to make a car that is brilliant in every way. It doesn't rust. It's engine goes on forever. You can go to the moon and back if you change the oil regularly in one of those, but they won't make more than 10 or 15 years old because that digital dash will break. This is the problem facing car makers, that they've made incredible cars, but they don't want them to last forever. They want them to die. They want them to die early. I've used the phrase complexity as the new rust. When I started my motor in Korea, basically, we all had cars that were about 10 years old, but they were rusty as anything. We got to know body filler and all the tricks to get them through the APK, the MOT in the UK. Nowadays, you have a 20-year-old car and it's just rust-free. This is a miracle, but that's really bad for the car manufacturers. They've basically upped the complexity, where if something broke in the Herald, it would cost you 10 pounds, 15 euros, and a day with a screwdriver. If something breaks in the CMAX, you'll take it to the dealer and they will say, well, that module will cost you 1,500 euros, and that's more than the car's worth, and so you scrap it. If you go into a modern scrapyard, you will find it is full of cars that, back in the 80s, when I started driving, we could only dream of cars with perfect engines, perfect bodywork that are only in there because something too complex and too expensive has broken. So, here we are in 2022. The problem with electric cars is that electric car is fundamentally a very simple piece of kit. If you want to see how simple an electric car can be, if you go around these hacker camps, you'll probably see hacky racers. If you see my friend Mike's, little tykes, a cozy coop thing driving around, that's a hacky racer. That's an electric car stripped to its essentials. That is not road legal, but it's a good illustration of what you need for an electric car. You need a floor pan platform, so you need something with wheels, suspension, brakes, et cetera. You need an electric motor and a transmission. You need a motor controller, you need a battery manager, and probably you need something to manage the anti-lock brakes. That's three computers, three microcontrollers, and you can make a road legal electric car. A transmission controller, power management, and anti-lock brakes. These are not the electric cars we're getting.   You know, toys. You didn't pay for some heap of shites with like just one dial. You paid for the experience. The trouble is, particularly with things like Teslas, Teslas go out of support before they're 10 years old. Teslas, actually Teslas also have awful build quality. I think I would prefer a U-Go to a Tesla, because I actually prefer a car with build quality. The problem is we're repeating exactly the same problems as we did with the petrol cars beforehand. That we're producing zero tailpipe emission cars that won't be put off the roads by emissions legislation. And so the manufacturers are making damn certain they come off the road by loading them with unnecessary features and integrating the features. So when the technology dies, the car dies. And I would be prepared to put money on it. If I were to walk into a scrapyard in, let's say, 2030 or 2035, I would find it full of Nissan Leafs and Teslas and E-Golfs and, oh God, what's the other, your normal crop of current day electric vehicles that are in perfect condition. They still have plenty of capacity in the battery. They have no rust. They look as though you could drive them away, but they will be dead and they will be in the scrapyard because some loaded extra feature has died which costs a fortune to replace and the owner has just said, I'm going to scrap it. And thus, I'd say that when environmental soundness is linked to longevity rather than to tailpipe emissions, an electric car that lives for less than 10 years or even less than 20 years isn't environmentally sound at all. I think I'd rather go a more environmental route. I might hazard a guess that driving a diesel pickup truck fuelled by endangered whale oil would probably be more environmentally sound. Oh jeez, there it goes. Help. Oh, we're back. Yay. So coming back to what I said about the hacky racers. Electric car, this is actually a prototype Ford electric car from about 1914. And as you can see, it's an electric car stripped to the minimum. Personally, looking at that, it's got brakes on the back wheels only and it's got lead acid battery and it's got no safety features whatsoever. Maybe that's a bit too minimalist. But really, it comes back to what I was saying about the hacky racers. To make an electric car, you do not need all the extra things. It's a genuine opportunity for manufacturers to throw away the baggage and make much simpler cars with longevity in mind. If they're serious about environmental soundness, they need to look at the way they make cars and make them for lifetime environmental soundness, not just the smug feeling of the first person who drives it off the forecourt. So this is something I came up with for Hackaday a while back, the minimal motoring manifesto, which is, this is how I want to see cars made. I don't know if you lot agree with me. I'm guessing they'll probably be one or two automotive engineers in the audience who will tear me to shreds in the comments.  Personally, I would like to step into a car, something like a Willys Jeep, with one dial in front of me and minimal controls. But I realise, not everybody is like me. People expect the toys, they want the toys, they've earned the right to the toys. Yeah, fair enough, you should have toys in a car if you want to. But car design needs to be able to deliver the toys without delivering that built-in planned obsolescence of one thing breaks and the whole car is scrap. So here's the manifesto. Separate the subsystems. Why are unnecessary subsystems integrated closely with necessary ones? Why, when something that is unnecessary for the car breaks, do I have to replace a module which costs a fortune because it runs every other subsystem on the car? Why, when something unnecessary on the car breaks, can I not just ignore it and keep driving and keep going for an APK or MOT and keep the car on the road? When my Triumph Herald is a bad example because it has no toys. OK, when my Polo 6N's air conditioner died or central locking died or any of its other subsystems, and believe me, all its subsystems did eventually die, I could keep driving the thing because it still had enough of its subsystems separate that it kept on the road. The speedometer worked, the lights worked, whatever. That focus CMAX, if almost anything dies, anything affects that can bus, whatever.   My next thing on the manifesto is provide a minimal way in. Now, we're all familiar with OBD2. Most of us have probably got one named little Bluetooth dongles, you plug into your car and you can read off all sorts of interesting stuff. Now OBD2 is great, it's a standard because some parts fit a standard. Now of course every manufacturer has extended the standard and made it non-standard. I would suggest, I would like to advance the proposition that we need a standard for essential services in a car. So if something very expensive dies and means that you can't get it through an APK, you need to be able to unplug that digital dash or that module and throw it away and drop in an open source one that provides the essential services needed. Throw away the toys, just put in an open source speedometer or whatever that just works. The last one is if you read reviews of mobile phones. I know this, I'm a journalist, when you're writing a review of something you need to find something to get excited about. I pity people who review mobile phones because all mobile phones are basically the same. They're a black slab. This is actually quite galling. If you pay a thousand euros for an iPhone, you get a black slab.  They look absolutely identical from a distance.  But it's basically, sorry, it's a black slab. This is the same problem with cars. There was a time when cars were all different. If you go back to the 1970s, you could genuinely, if you wanted a car with a rear engine, there were several ones. If you wanted a car with adventurous styling, there were several ones. If you wanted a real-world drive car, you could take a choice. But to be honest, now you look at the models from the main manufacturers and you can't get a cigarette paper between them. They're so similar and they're all very bland. When you read reviews and things, the reviews are all about the toys in the cab because the poor journalist has got nothing else to write about because the car itself is so boring.  My friend used to try to start a business in kit cars and it failed. He came to me and he said that the car business is either one of two types of people. You're either a crook or a dreamer. I'm not in the car business but I realise that the thesis I've just delivered makes me a dreamer because it's never going to happen. It's not in the interests of car manufacturers to make cars that last longer. They want to flog cars. But still, if we're living in late-stage automobile design, the automobile is about to change and shuffle off this mortal coil as we know it, we still don't have to like it. Anyway, I've been to any list. If you like this talk, I'm going to talk to you for a very short while about Stishing Transrescue Foundation. This is the non-profit of which I am treasurer. We're actually based over by the Badge tent. We help transgender people get out of very dangerous places. We're unashamedly here to raise money. If you'd like to come and talk to us, if you'd like to donate, please come and do so. Anyway, thank you very much. Does anybody have any questions? You can tear me to shreds. If you have any questions, please walk to the mics and you can ask them. Hello. Are you first? Okay, thanks. Thank you. It was very interesting. I drive an electric car. I had been researching which car to drive for months and ended up leasing for the first time in my life because that wasn't the perfect car. Yes. But I was wondering, did you hear about the Sono Motors car which comes only in one variety and has a photovoltaic system? Do you repeat the make of the car? Sono Motors, S, O, N, O. Okay. Is that the one that looks a bit like a Volkswagen micro bus? I think so. You can just get it in black and it has solar panels all around and their goal is to make a simple car. Have you heard about that? That is a wonderful idea. I have seen more than one attempt to do that. However, I'll refer you back to the Crooks and Dreamers slide. I would love to drive a car like that, but all the ones I've seen, I may not be quite familiar with the one you've described, but all the ones I've seen are either way more expensive or the company basically isn't going to belong to this world. I really want a car like that and if I could get one, that's great, but I'm afraid I would end up paying a lot more money than I can afford and I might well end up with something with zero spare support because the company's gone bust. Actually, I'm not sure if they are getting ready. We had reserved one and it's delayed, delayed, delayed and I've heard mixed things, so I was wondering if you know about it and what your opinion is. I may not be familiar with that particular one, but I've seen quite a few. I'm a motorcyclist as well as a driver and there are also some very exciting small motorcycles in the 125cc class and it's not impossible as a lifelong car driver and a motorcyclist, I might actually become purely a motorcyclist for the same reason because there are some simple ones there. Thank you. Hi there. I won't shred you to threads because I really liked your talk. Thank you. I always bought old cars and I did a lot of repairs on them until indeed the cars became too complicated to do it myself and recently a log failed and I had to like the ignition log and I had to pay 400 euros because it had to be reprogrammed. I was amazed. I kind of fell over complexity as the new rust, whether it's the intention of the manufacturers to make a car that is very obsolete, obsolete very soon, because I'm wondering whether, I mean you're blaming the manufacturer but I think the manufacturer is also driven by us as consumers. So my question is the deliberate choice of the manufacturers or is it lack of critical consumer feedback? I would say there's an element of both because of course the consumer, because the trouble is the consumer, as in you and I, is different from the consumer who buys the cars because people who buy new cars they don't buy them for the same reason we do. And yes you're right, the consumer just wants toys but the manufacturer is consciously making cars that are bad for maintenance. The manufacturer is consciously making cars with software licenses.  The manufacturer is enthusiastically embracing this so I'm still going to go with the manufacturers here. Yeah but if you look like a fair phone to look at the phone side, they kind of try to do what you're suggesting to make it modular. I'm going to answer that though. Outside this field, who has a fair phone? Yeah, exactly. I mean great, there is a fair phone but the fact is that virtually nobody outside our community has heard of it. So I would say that you're right, fair phone are doing the right thing but they are a very niche manufacturer. If Huawei start doing that, then I'm listening. But I would say that that approach is great but I don't see any of the big manufacturers doing that. Yeah and that's why I think that... Let's take this discussion offline and please give the next question. Thank you. John. So first of all, I would like to thank you for addressing this because I think it's a real issue, especially when the population is growing and more and more people want or need cars. At the same time, I would like to ask because this still revolves around car ownership because you have a car and at some point it stops working and you need to repair it or buy a new one. And now, hypothetically, if there will be a future where car ownership isn't the norm because most cars, they are produced, then they are in parking lots for over 90% of the time, which is kind of a waste of resources, I'd say. So what if cars would not be personal property but rather be a service people can make use of? Would that change the conclusion of your thesis? Well, it would still mean that those cars, if they're over complex, would go on the scrap heap quicker, which basically means that they are in less environmentally sound. So it doesn't change what you might call the hardware part of the thesis, but also it's the same thing with cloud software. When I pay for something, I want to own it. I don't want somebody else to own it.  But there are things where I draw the line. I want to own something. I want to own my CAD package. I don't want it in the cloud. Thank you, Autodesk Eagle. I want to own my car because I don't want somebody else to harvest my every use of it and sell it to somebody else. I don't want to be beholden to an evil corporation on it. So there's the hardware side of it that it doesn't matter who owns the car if it's on the scrap heap in five minutes. That's a bad thing. But there's also the ownership side of it that I want to I want to be able to use my car on my terms. Also, I grew up, it come out in Britsa Bordari. I grew up on a British farm. And these kind of shared models sort of cars as a service, they're great if you live in a town. But most people don't. And most people don't live in the kind of town that has that kind of thing. If you live in a hollowed out town in the hinterlands, you're not the first people to get these services. You're the last people to get these services. So there's still a big need for people to have vehicles they own, I would say. But from a hardware perspective, I would say the same completely applies whatever the ownership model is, if the car is on the scrap heap before it's time, then it's not sound. Fair enough, thanks. I'd like to disagree with you. Please do. First, I think we're having a people problem. As you said to the questions before, people want gadgets. You shouldn't be angry at car manufacturers, but you should be angry at people that just want to live with it. Or try to change and educate people to be more sensible of this thing. And I'll take you on the 2030 bet. I'm sure there will be not many cars in perfect condition in scrapyards. And another thing, sorry. Cars are pretty resilient. Like in a Tesla, you can remove the centre of view and you lose air conditioning and some commodity features. The car still runs. When I came here, I was playing with a can bus of a Tesla and I shorted the motor control bus, can bus. And it still drove fine. And it just disabled regenerative braking. But there are also many open source projects that are addressing this. Like there's open source, as you said, speedometers. Like an acrofondroid with an ASP32 connected to the can bus that works. And I'm sure there will be a thriving community in this kind of project that aims to remove the MCU and make the car number as you like it. But I think it's also a generational problem. Like people with carburetors were complaining when injection got introduced. And it's also... The world is more and more complex every day. So everything is more and more complex. It's like entropy. It's still accessible. You can still route a Tesla. You can still reverse engineer a can bus. It's just more difficult. I would turn around. On the first point, I'd say that it comes back to that separate the subsystems thing. Fair enough the customer asks for the toys. The manufacturer is not separating the subsystems. But also I would say that yes, there are all these open source projects and they are absolutely great. The trouble is they are not accessible to the kind of people who are not on this field. And it's great. Yes, it gets more complex.  Basically that Triumph Herald, as I say in a lot of ways was an awful car. But almost anybody in his backyard with a screwdriver could maintain it. Now obviously we have moved on since Triumph Herald. I agree to making it easier for somebody who isn't on this field. And I agree there are some wonderful open source projects. But I have an electronic engineering degree. I can do this. But I don't think it's fair to expect the average bloke on a estate in my hometown of Bista to also be able to do it. Yeah, but where there's a wheel, there's a business. So if many people want this, the people from the open source project will manufacture a product that you just plug in. There are many projects that went this way. We've had these things for quite a long time in those businesses that haven't appeared. And meanwhile, there are a few businesses like that, but it has not a mass market thing. Please move the discussion to outside and give room to the next question. By the way, if we come along to WTF 2033, there's a club martyr in that bet. Hello. So a very quick one maybe. We are adding the complexity to the systems to the cars to increase the safety. So in the 1970s, the car that you just show, we had about 20,000 people dying in Germany alone and road kills a year. Now we have about 2,000. So we are saving 18,000 lives a year. I mean, we can reduce airbags, we can reduce ESPs, we can reduce all of these microcontrollers, all of this logic. Right now we are adding all the compute to the cars to save lives. I would disagree with you. Obviously a lot of technology in the car for safety. There is the design of the monocoque. There is the metallurgy of the monocoque. There are things like crumple zones. There are reactive systems like airbags and stuff like that. But the kind of things I'm talking about are not the essential safety systems. They are the ludicrous amounts of extra complexity and non-essential systems that is tied into the rest of the car. Of course we need safety systems. Oddly, that triumph herald is actually one of the safer cars I featured there because it has a separate chassis. There is test data on 1970s crash tests on the triumph Spitfire in which it actually came up quite well because the chassis just goes yonk. But that's an outlier. Safety is obviously an important thing but I'm not talking about safety systems here because it's not the safety systems that are the problem. Any other takers?  Come at me. Well, if that's all then thank you very much and thank you for being a polite and attentive audience.


I've got my pen. Now, we were in the stomach, we passed through the pyloric sphincter, and we are now in the small intestine. And there are actually three parts to the small intestine, and so I feel like we should probably define those parts right away. So the first part of the small intestine that we enter is called the duodenum. Duodenum. The duodenum is pretty short. It's about 10 inches long, and it forms like kind of a C shape directly out of the stomach. The duodenum feeds directly into the next piece, which is called the jejunum, jejunum. So check it out. Hey, look, they even labeled it here. Stomach enters into the duodenum. In the duodenum, dude, they done forgot something. Really? That's just messed up, because you forgot the jejunum. What do you think the next piece of small intestine is called? The ilium, I-L-E-U-M. Now, spelling and anatomy always counts. An ilium is a word that it is easy to forget, that it is an E in the word ilium, especially since there actually is a bone in your pelvic girdle called the ilium, but it's spelled different. It's spelled with an I.  The ilium is the longest. It's over 10 feet long. The jejunum, I think, was seven and a half feet long. Dude, the small intestine is huge. It's really long. And what's happening in here? There are two primary events that are taking place in this whole thing. Number one, chemical digestion. And number two, absorption. Chemical digestion. We're dumping in enzymes. Most of the enzymes are dumped in the duodenum. Enzymes and other juices enter here. And when we look at our accessory structures, like the pancreas and the liver, check it out, you can even see it. We have ducts from the liver and the gallbladder and from the pancreas. And those ducts dump juice into the duodenum. And the juice that they're dumping is full of digestive enzymes that help you break down the food that's been mechanically churned in your stomach and chomped in your teeth. And now we need to break it down with chemicals so that it's really, really simple and small. So then you can actually absorb it into your bloodstream. And that's the small intestine, that's its job. Now, if the job is to chemically digest, then it makes sense that we're going to have a place where we can dump chemicals in and that's in the duodenum. It also makes sense that we would have time to do that chemical digestion. And in order to have the time to carry out the chemical breakdown, the small intestine better be pretty long. The food better stay in the small intestine for a relatively long period of time. And it does because, dude, that being the length of the small intestine is huge. So it takes a long time to get through the whole thing, which gives you a lot of time to do the chemical digestion. If you are going to be an efficient absorber, then it makes sense that we would have a high surface area in lining the lumen of our tube as possible. The more surface area you have, the more area, the more surface area you have to actually absorb the substances into your body. So there are several ways that the digestive system deals with the surface area issue. First of all, you have more surface area if you're long. So the length of the small intestine contributes to its ability to increase the surface area and be more effective at absorbing nutrients. The small intestine also has these structures called circular folds. And you can't see them in this image right here. I'm wondering if I have any images where you can't see it. But a circular fold, here's my tube, you got it. And a circular fold is just a place where the tube narrows and then it gets bigger again. Okay, I have to draw you a picture because look at how a circular fold works. We'll make our digestive tube, look at this. Here's my tube and then it narrows down and then goes back to the original size. That's the circular fold. It's kind of a big end, gosh. This kind of makes it look like it has, like, one finger that's coming out. But that is supposed to be one whole tube with these kind of constrictions around the whole tube. So if I went in and looked at it, I actually would see that, you know, this part of the tube would have to be this big. But this part of the tube, I could actually, like, fit a tiny little rubber band around it because it's actually narrower.  That as opposed to just that. Makes sense, right? Okay, so the circular folds are another way to increase the surface area. You also have structures all through the small intestine called villi and this is really interesting too. So watch in addition to your circular fold, which is the entire tube narrowing, lining the tube itself all the way along, even in the narrow parts. Okay, so I'm going to take a cross section right here and I'm going to draw you a picture of the tube from this aspect, from a cross section looking down it. And you actually have these structures called villi. Whoa, these are all villi. Do you even know what in the world I'm drawing? This is one villus. Here's another villus. Do you see that? These villi are finger-like projections extending into the lumen of the tube itself. So the tube narrows but the tube is also filled with these finger-like projections and all they do is increase surface area. Now, there's one more thing that increases the surface area and it's called microvilli. They are called microvilli. And I'm going to write it down here.  Look, I can even fit it on here. Are you ready? Now I'm just going to take a slice. I'm going to take just... I'm going to take one villus out of this picture and this is what I'm going to do. Here's my single villus that's extending into the lumen of my tube. And we know that the villus is actually lined. What would you think? By what kind of tissue? Epithelial tissue, right? And we actually looked at this epithelial tissue. It's a simple columnar epithelium. So this whole thing is a villus. That whole finger is a villus. Are you ready to find out the amazing and fantastic microvilli? First of all, do you agree that this is one cell?  That's what is on the lumenal end of these cells. What? Little microvilli. So let me clarify this because this makes it look like they're not attached. I wonder if I can erase that. I love this program. Look at that! And every single one of them has it except I just didn't take the time to draw every single one.  We have a whole bunch of them. And they all line the lumen. What? So if you were going to do a compare and contrast, microvilli to villi, villi are made of multiple cells. They're an entire structure sticking into the lumen of a tube. And microvilli are similar, little extensions, but they come off of a single epithelial cell. And we should be able to see those when we look in the microscope and do some digestive histology. Hmm, hmm, hmm, hmm, hmm. Okay, we're going to talk about the accessory structures later on, so I feel good about this treatment of the small intestine. Let's look at the large intestine.


So far we have discussed about some examples of steady flows in the paradigm of low Reynolds number flow. Now we will discuss something more about steady flows later on and we will discuss about a theory which somewhat generalizes the elementary low Reynolds number hydrodynamics that we have discussed and that theory is known as lubrication theory. So we will discuss about that in details later on but prior to that let us move into some cases of unsteady flows. So let me talk about little bit of motivation as we discuss about the unsteady flows. So when we discuss about unsteady flows remember that whatever we are discussing here is in the broad with the broad motivation of studying some examples related to microfluidics. So we are proceeding towards that direction in many ways. Now we will start with an example of an unsteady flow with a classical problem which is not a problem of microfluidics that is Stokes first problem. So the Stokes first problem is something like this. You have a solid plate and there is a fluid over the top of the solid boundary. This fluid is initially stationary. Now you suddenly pull the plate with a particular velocity say u equal to u0. Then because of the movement of this plate there will be a disturbance in momentum in the fluid which will be propagated by virtue of the fluid property viscosity. So you want to see that how does this momentum disturbance get propagated as a function of position and time. That is as a function of the y coordinate and the time coordinate. Now what is the relevance of this problem in microfluidics? See this is not a microfluidic system. In fact this is not a confined system. Now in microfluidics there are several effects which come into the picture. One possible effect is the effect of confinement. That is if you make a plate coming on the top of this plate with a small gap between the two plates then it becomes a confinement. So the question is that how does the confinement affect the flow? To understand that we will first solve this problem when we will consider that there is no confinement. See if we want to understand what is the effect of confinement first we have to study that what is the scenario when there is no confinement and then in the next problem that we will be solving we will put a plate at the top of this one. So it becomes a confinement and we will see what is the difference between the results in the two cases and that will give us an indication of what could be a possible effect of confinement in unsteady flows. That is one of the classical motivations. I will talk about some more motivation later on. So as we proceed so when we get a little bit bored with the mathematical exercise we will talk about some practical motivation to compensate for that. So let us start this working out this problem by writing the governing equations. So let us assume that the velocity u is a function of y and t. It is not a function of z because the plate is considered to be of infinite width. It is not considered to be a function of x that is not fully developed flow to be in a literal sense because fully developed flow we generally talk about in the context of internal flows that is flow through channels pipes and all this. But the notion is similar that there is a translational invariance that means if you want to look into the velocity field at this location the same velocity field will be repeated if you go to a different axial location. If you translate and move on to a different axial location that is called as translational invariance. So with that u is a function of t and y or y and t whatever. So this is equal to so the left hand side of the Navier-Stokes equation will have this unsteady term. Remaining terms will not be there because u del u del x plus v del u del y del u del x is equal to 0 and as a consequence from the continuity equation v is equal to 0 that we have already discussed. So that means the remaining terms if u is not a function of x the remaining terms are not there but unsteady term is there that is the basic difference between the previous problems and this problem that they are the unsteady terms were not there now the unsteady term is there. And because of the length scales involved the dominant viscous term is the viscous term which is mu del 2 u del y 2. The x length scale is being much greater than the y length scale this term is dominating as compared to the gradients along x. There is no pressure gradient because it is like an infinite flow medium where it is subjected to like uniform like atmospheric pressure from all sides. So it is an open problem.  Now as we can clearly see that the problem is dictated by the kinematic viscosity. So mu by rho we can write this as nu and the problem is dictated by the kinematic viscosity. So here what will be the time scale? The time scale will be we have discussed about 3 possible time scales. The advection time scale, the diffusion based time scale and the forcing based time scale. So here what will be the time scale? It will be the diffusion based time scale because you can clearly see that these two are competing with each other. Now there is a time scale associated with the problem but there is no natural length scale. There is no natural length scale involved. So why is there no natural length scale involved? Because there is it is not in a confinement. If it had it been in a confinement the height of the confinement would have been the natural length scale but it is an unconfined medium this is like in this is extended up to infinity. So there is no natural length scale but it is important to figure out that what could be a possible natural length scale based on the time scale. So what is that length scale? Length scale means the distance up to which the effect of this movement of this plate will be felt. So question is that on which factor is that distance related? One of the critical factors on which it is related is time. So if you allow more and more time, more and more fluid in the outer layer will feel the effect of the plate. Theoretically if you allow infinite time all the fluid will feel the effect of the plate but in a very short time only a small extent or a short depth from the plate will feel the effect of the solid boundary okay. So time is an important parameter. Is there any other important parameter? Yes, kinematic viscosity we have discussed about that. But more is the kinematic viscosity more will be the effect or the penetration depth of the effect of the movement of this plate. So the length scale up to which the disturbance due to the motion of this plate will be felt should be increasing with time and should be increasing with kinematic viscosity. But exactly how? To understand that we will make an order of magnitude analysis of this equation very simple analysis. So what is the order of magnitude of this term? U reference is U0 by T reference. This is of the order of nu U0 by y reference square. So y reference scales with square root of nu T reference okay. That means although there is no natural length scale in this problem but the length scale is eventually decided by the kinematic viscosity and the time scale okay. So from here we can qualitatively expect that U by U0 will be a function of y by y ref. And this function is expected to be self-similar. This is very much analogous to the boundary layer theory where velocity profiles like if you draw an analogy with the boundary layer theory if you have this is the boundary layer velocity profiles at various locations are indeed very different. But if you non-dimensionalize or normalize the velocity profile U by U infinity as a function of y by delta this being delta this being the nu delta at the nu location. So U by U infinity will be a single valued function of y by delta. Here the delta is this one that is the penetration depth just like the boundary layer okay.  Is this delta it is a function of t right this we could get from a physical intuition. So we can write that U by U U0 is a function of y into a function of t right this gt roughly scales with 1 by delta okay. So we can because it is a single valued function of this we can write replace this with a variable eta which we call as a similarity variable okay and seek for a solution and when you express the solution in terms of this similarity variable again just like method of separation of variables the similarity transformation the objective is to convert the partial differential equation into ordinary differential equation because if you are able to express this as a function of eta as a single variable then it will be a U by U0 will be a function of a single variable only. Question is is it always true I mean is it always possible to cast this type of PDE into in the form of an ODE like this depends on the physical situation on hand in this physical situation it is possible. So I mean there are situations when that may not be possible but here the physics is giving us or driving us towards this kind of variable separation. Now we will proceed with the solution of this problem so U by U0 is a function of eta where eta is equal to y into gt. So what is del u del t U0 df d eta into del eta del t right using the chain rule. So del eta del t is y into g dash right where g dash means dg dt then del u del y del u del y y we require del u del y because we need to evaluate this term. So del u del y U0 df d eta into del eta del y so U0 df d eta into g. So what is the second derivative? Second derivative is U0 so you basically make dd eta of this into del eta del y. So another g will come so it will be U0 d2f d eta 2 into g square.  U0 gets cancelled from both sides so g dash by nu g cube is equal to d2f d eta 2 by eta df d eta right. So we have clubbed all functions of t in on one side and all functions of eta on one side. So this is function of t only this is function of eta only. So these 2 are the same only if it is a constant. So let us say that the constant is c. So we can write dg dt, g dash is dg dt then 1 by nu g cube is equal to c. So g to the power minus 3 dg is equal to nu c dt. So g to the power minus 2 is equal to by minus 2 is equal to nu ct plus c1. Now we have to remember that what is g? So g is what? g is 1 by g is the penetration depth at a given time right. So at t tends to 0 what is g? At t tends to 0 the penetration depth is what? The penetration depth is what? 0. So g is 1 by the penetration depth that will tend to infinity. So at t tends to 0 g tends to infinity that means c1 will be 0. So you have g is equal to 1 by minus 2 nu ct square root. So you can see so this is the beauty of scaling analysis. Say a rigorous mathematical analysis has given rise to this form of g but you could tentatively get this form without going into this mathematical analysis simply by scaling the two terms that are appearing in the governing differential equation. So you will clearly get that g scales with 1 by square root of nu t. Remember that g is 1 by y reference. y reference is scales with square root of nu into t reference that is what is sort of supported or justified by this more detailed mathematical treatment. Now the question is what is the value of c that you may take? So only restriction is that c has to be negative because this g has to be a real number. So c must be negative. So what is the typical choice of c? So that depends on convenience. So you may choose for example c is equal to minus half or 2 minus 2 like that so that you know the square root business goes off. So as an example let c is equal to minus 2. So then remember this is not a must. This is just one example. So whatever c you will take it does not disturb this equality. So you recall that in school level ratio of proportion problems a by b equal to c by d equal to k whatever k you take that does not disturb the equality of a by b and c by t that is what is important. So this equality is never disturbed because of the presence of this c. So for different c the solution of g will be affected and the solution of f will be equally affected. So I mean different c's will eventually give rise to the same solution. So you will have g is equal to minus 2 as an example. So c is equal to minus 2 as an example. So g will be 1 by 2 square root of nu t. This is about g. Now let us concentrate on f. So you can see that we have now been successful in converting the pde into an od. We will write the boundary conditions immediately but before that we will just integrate these ones. So the boundary conditions maybe we can write first and then integrate. So what are the boundary conditions of this at eta equal to 0 what is f? f what is the definition of f?  So at eta is equal to 0 what is u? u is u0 no slip boundary condition. You have to be careful here the plate itself is moving. So no slip boundary condition does not mean that the fluid is stationary. It means the fluid is stationary relative to the solid boundary. So if the solid boundary is moving with the velocity u0 the fluid will also move with the same velocity u0. That is what is the no slip boundary condition. So if u is equal to u0 then what is u by u0? 1. So at eta is equal to 0 f is equal to 1 and at eta tends to infinity f will be 0 because far away from the plate effect of the disturbance of the plate will not be failed. So the velocity will be 0. So our problem definition boils down to this. Now to solve this problem I mean it is a very straight forward solution. Let dfd eta is equal to some h. So you have dhd eta plus 2 eta h is equal to 0. So dh by h is equal to minus 2 eta d eta. So lnh if you integrate is equal to minus eta square plus ln of c2. We have already used a constant c1 for this problem. So let us give it a name c2. So h is equal to c2 into e to the power minus eta square. What is h? h is dfd eta. So what is f? c2 e to the power minus eta square d eta plus c3. Now we will apply the boundary conditions. So these boundary conditions let us give names. This is boundary condition number 1. This is boundary condition number 2. So the boundary condition 1 what does it say? The boundary condition 1 says that at eta equal to 0 f is equal to 1. So that means c3 is equal to 1. So you have f is equal to 1 plus c2 integral 0 to eta e to the power minus eta square d eta. We apply the boundary condition that at eta tends to infinity f tends to 0. So the boundary condition 2 0 is equal to 1 plus c2 integral 0 to infinity e to the power minus eta square d eta. Then we can make a substitution that eta square is equal to z. So eta is equal to z to the power half that means d eta is equal to half z to the power half minus 1 dz. So 0 is equal to 1 plus c2 by 2 integral 0 to infinity e to the power minus z into z to the power half minus 1 dz. By definition 0 to infinity e to the power minus z into z to the power n minus 1 dz is gamma of n. So this is gamma of n is equal to half, gamma function of half and gamma half has a value of root pi. So c2 becomes minus 2 by root pi. So f becomes what? 1 minus 2 by root pi integral 0 to infinity e to the power minus eta square d eta. This is the error function of eta, erf eta, sorry 0 to eta, not 0 to infinity, yes, 0 to eta. So we write the solution here f is equal to u by u0 is equal to 1 minus error function of eta where eta is equal to 1 by 2 root nu t. So 1 minus error function eta is also called as complementary error function, erfc. So that completes the solution of the stokes first problem. Now how will the velocity fields vary? We will look into that but as we are doing for most other problems, we will recapitulate through the slides what we have done for the stokes first problem and then we will look into the graphs which will give the solution for this velocity field, basically a visualization or the plotting of this velocity field. So if you look into this, so we have used this similarity transformation and I am just browsing through it. So now we can see, you can, so in the similarity variable transformation, we have written f as a function of eta and g as a function of time, we have separated these variables and then we have integrated to find out that expression for g, c can be any negative real number we have chosen c equal to minus 2. Then we have considered the governing equation for f and we have integrated the governing equation for f by assuming, by letting f dash is equal to h and then that has given rise to the solution by substituting the necessary boundary conditions and these boundary conditions eventually give rise to the solution that f is equal to 1 minus error function of eta. Now it will be interesting to see how the solution looks graphically. So if you look into this graph, you will see that u by u0 as a function of y by 2 root nu t, you see that the effect of y and time, effect of position and time they are coupled. So that is the first important observation. See if you are asked that what is the value of velocity at a given y, then it depends on what is the time. So if you allow more and more time, the same velocity will be appearing at a greater depth from the plate. The simple reason is that at greater time more and more amount of fluid will now feel the influence of the solid boundary. So if you have higher value of t, you will get a higher value of y for which the same velocity effect is felt. That is why when you map the solution u by u0 as a function of y by square root of nu t that coefficient 2 is of course not that important from a concept actual point of view from a mathematical data point of view that is important but concept wise it is y by square root of nu t that dictates that what will be the solution of the velocity as a combined function of position and time. Now if you are interested to plot the velocity in a dimensional plane, not in a dimensionless plane. So that is shown in the second graph where you plot for some problem u as a function of y for different time. So you can see, so look at these extreme diagrams, extreme curves. So the first one say this is for a short time t is equal to 0.1 second. So only a small depth from the solid boundary feels the effect of the plate. But as you allow more and more time say t equal to 4 second for the particular data that has been assumed, you can see that now the penetration depth is much beyond what it was for 0.1 second. So the penetration depth becomes more as you allow more and more time and it depends critically on the kinematic viscosity. If the fluid has a greater kinematic viscosity at a given time the penetration depth will be more. So that is what we have learned from the Stokes first problem. Now the thing is that this problem is very interesting and classical. Now how can we relate this problem with microfluidics? So we will consider a problem which is a little bit deviated from the Stokes first problem but has some kind of notional relevance with that. So in the Stokes first problem you had a solid boundary moving towards a particular direction with a velocity. Then what we do is that to if consider the effect of confinement we put another plate which is on the top of this. So this is in the steady state the classical quet flow problem. You have flow between 2 parallel plates. One of the plates is moving relative to the other with a particular velocity that is the classical quet flow. Now we are interested in the unsteady solution of this problem not really the steady solution. Now question is many times this kind of question comes to our mind that when we study fluid mechanics these kinds of classical problems are always introduced and microfluidics is of no exception. So people might talk about that well in the introductory lectures in microfluidics on one hand you talked about cell, DNA these that and suddenly you are going to an abstract problem when a plate is moving relative to the other what is the physical relationship between these 2 and I think I have a responsibility to discuss about that before entering into this problem. So now in teaching pedagogy it is important that we discuss about certain things in the context of why we are studying that. So when we are studying quet flow for example forget about steady or unsteady. When we are studying quet flow the basic reason that should come to our mind the basic question that should come to our mind is that why are we studying quet flow that relevance should be brought in. When we are studying a poiseuille flow again poiseuille flow that motivation is very clear that you have a pressure gradient driven flow and you in reality in engineering systems you may have a pump to drive the flow. So that motivation is quite clear but when you are thinking of a quet flow that motivation is not very obvious. Where have you seen somebody pulling a plate on the top of a fluid and moving the fluid in that direction. I have not seen anybody doing that I do not know whether I will come across that example in the remaining part of my professional career but I have never seen that. But I have seen people pumping water through pipes and channels that I have seen. So somebody is suddenly pulling the plate in a particular direction and allowing the fluid to move of course you can make such actuators not by somebody literally manually doing it but doing it by a mechanism that is possible but there is actually a broader motivation towards this. So when we work out the steady state solution of this problem you will see that the shear rate like if you set up your x axis in this direction and y axis in this direction the shear rate will be u0 by h and the steady state velocity profile will be linear. I mean from your undergraduate studies you already know about that and we will revisit that quickly while working out the unsteady state solution. So then if the shear rate is u0 by h you can control the shear rate by controlling u0 or by controlling h. So that means you and this flow is acting this is a pure quet flow without pressure gradient. You can have a quet flow with a pressure gradient that is called as quet Poiseuille flow that is a combination of pressure gradient and the this effect. So this effect is giving what? It is giving rise to a shear rate which is a constant or the rate of deformation which is a constant. So you can have a design rate of deformation or the rate of shear on the flow and then study what is the response of the flow against that rate of deformation. So this is called as shear driven flow just like pressure driven flow this is a shear driven flow and this is just one manner in which you can impose the shear by moving a plate. But if you could apply the shear by whatever by a different mechanism and study the shear driven flow mechanism study the response of the system against that shear then if you have shear of this magnitude then the response to the system you can study as a function of shear of this magnitude which can be controlled independently by u0 and h. Not only that you can see like all of you have seen that you have a parabolic velocity profile for a fully developed pressure driven flow. Now let us say that this dimension is over a few millimeters. Let us say there is a biological cell which is sitting on the wall of this channel this is let us say this is few centimeter or millimeter this is like say this is what around 10 micron roughly. So over the span over which this cell is sitting you can approximately linearize this velocity profile. So a small part of the parabola is like a straight line right a very small part of the parabola this is actually this is exaggerated in a figure but this is actually very small. So that means if you have a cell sitting on the surface of a blood vessel and is subjected to shear of a given amount then what is the response of the cell against that shear if you want to study that this can be one of the basic mechanisms of probing the fluid mechanics in presence of that kind of physical situation okay. So you can see just I just wanted to I mean I can get into deeper discussions on this but we will not spend much more time on this before getting into the mathematical analysis but my whole objective of telling this is to convey this information to you that whenever we are doing mathematics for solving a problem never try to think that we are doing mathematics for the sake of doing mathematics. So we have to keep in mind that there is a broad picture in mind and the broad picture is a very complicated picture to get the essential physics of the broad picture to begin with we can simplify the problem to a considerable extent and study the essential simplified problem of relevance and that is one of the motivations of studying the quiet flow. Now the governing equations are still very similar as the previous problem right because putting a solid boundary at the top does not change the governing equation it changes the boundary condition. So the governing equation is still this one but what is the most fundamental difference between the previous problem and this problem right the length scale. In the previous problem there was no natural geometrical length scale the length scale was a function of the time scale. Now here there is a natural length scale which is the height h still one may argue see these are deeper and deeper discussions I am trying to get into these and to ignite ideas in your mind. Now you have seen the solution of the Stokes first problem for very short time for very short time the penetration depth is very short let us say this h is greater than the penetration depth then this plate is actually as if located at infinity although it is not literally infinity see when we say in mathematics something tending to infinity in physics we mean that it is far field that means it does not feel the influence of the forcing effect it does not feel the effect of the influence of the forcing effect that is what is far field or infinity. So infinity does not literally mean that it has to be dimensionally infinity. So it may so happen that the penetration depth at a given time is shorter than this h. But in a microfluidic situation we are not we are not going to practically encounter such a situation because for the practical times whatever we will be considering the penetration depth will be greater than this micrometer dimension typically this is a very short dimension. So in microfluidics that we are interested about studying this problem independent of the Stokes first problem provided this h is the natural length scale otherwise it becomes the Stokes first problem itself. So with that motivation that we want a separate grasp of this particular problem we consider that h is the natural length scale. So what is the so if we do an order of magnitude analysis for this particular problem what is the order of magnitude of this u0 by t ref. What is the order of magnitude of this nu u0 by h square y ref square is h square. So t ref is of the order of h square by nu. So this is what this is the diffusion base time scale. So we non-dimensionalize the problem we non-dimensionalize the problem and write u bar that is non-dimensional u is equal to u by u0 non-dimensional y is equal to y by h and non-dimensional t is equal to t by h square by nu. See it is possible to non-dimensionalize by using different parameters. You could use here an advection base time scale also to non-dimensionalize but if you use the non-dimensionalization parameter as the correct physical parameter then the solution gives the correct physical meaning directly otherwise it needs further interpretation. So now del u del t is what del u del u bar del u bar del t bar into del t bar del t. So u bar by this is t ref in short we are writing this is t ref del u del y what is del u del y del u del u bar into del u bar del y bar into del y bar del y this is what so this is u0 by h into del u bar del y bar del square u del y square is basically u0 by h square into this another differentiation with respect to y. So if you write this equation then del u del t is equal to u0 by t ref u0 gets cancelled from both sides and t ref is h square by nu. So you can cancel t ref h square by nu so we will get that equation del u del t non-dimensional is equal to del 2 u del y 2 non-dimensional both of these terms are of the order of 1 because the non-dimensional parameters are so chosen that non-dimensional u is what u by u0 that is of the order of 1 non-dimensional y y by h that is of the order of 1. So all the terms are of the order of 1 now this problem will have a steady state solution and an unsteady solution. When will the unsteady solution be irrelevant? The unsteady solution will be irrelevant theoretically when we go to t tends to infinity. So at t tends to infinity we will get the steady state solution which is the solution for the quiet flow. So the general solution will be sort of the unsteady part of the solution plus the steady part of the solution where the unsteady part of the solution should tend to 0 as t tends to infinity. So we will work out the steady state solution separate it from the unsteady solution and then separately work out for the unsteady solution which should asymptotically vanish as t tends to 0 infinity. So we will take this up in the next lecture for the time being we stop here today thank you very much.


Hello aces, welcome back to module one lesson three today We're going to be talking about how to push through any obstacles by defining your why your vision statement and your mission statement It is crucial for us to learn How do we do that because we need to be able to harness anything we can? Harness our internals and our values and everything that we have inside to push through obstacles because Running a restaurant is not easy by any means We're going to be faced with tons of hurdles and struggles every single day and we need to be able to harness These three items in order for us to push through all the hardships And that's reason why it's super important for us to go through this module right now So what makes successful companies more successful than others? It is the way they lead Now let me elaborate most businesses small mom-and-pops we lead with what and then how what is it that we're selling? How do we sell it differently whereas successful business people they lead with their why? What is their conviction? How did they do it differently and what is it that they sell? Just by thinking and approaching this business from an upside-down perspective is the reason Why they're so successful Today we're going to be sharing with you the Golden Circle by Simon Sinek if you have not already done so Please please please go on YouTube Google Simon Sinek start with why it is a 10-minute TED Talk video that truly Explains the Golden Circle in such a way that it will change your life So definitely go and YouTube it but if you're not going to do that I'm going to explain to you as well Why what is your purpose? What is your cause? What is your belief? What is that internal thing that is pushing you to actually go and create your restaurant? What kind of belief do you have what kind of conviction and it starts from here? After the fact that you have defined that we're going to figure out how which is your process? What makes you do things a little bit different? What makes you stand out from the 10 million different companies and restaurants out there? It is the way you do things and lastly we go into what the result the tangible thing that you're serving is it ice cream Are they noodles are they chicken? What is it that you're serving? To give you an example of how apples Golden Circle works they lead with their purpose their why we believe in challenging the status quo and thinking differently How we challenge the status quo is by making our products beautifully designed easy to use and User friendly and notice we're still not talking about the product we're talking about why they exist and How they're doing things differently how they're different from Microsoft they make these things They're way ahead of their time before all the other companies really focused on user interface really Focus on the aesthetics of things Apple was the true leader and pioneer in that field and As a result, what do they sell?  In the morning and be excited to go to work Because you are doing something beyond yourself. It's a why it's the idea It's the belief that drives you out of bed every single day And it also is the thing that gives you the superpower to push through any hurdles any Hardships and believe me throughout the last 10 years running multiple different different businesses Every time whenever I'm faced with a really big dilemma of really big hurdle I always goes back to my own beliefs my own why why am I even doing it? And whenever I'm clear and whenever I remind myself of the why I Shrug everything off everything becomes worthwhile. I understand why I'm doing it And therefore I will continue to charge through the hardship that is in front of me right now My why? my why is to empower other people and to Provide them with an opportunity so then that way they can be the best versions of themselves and that truly is is my Why the reason why I'm so attached to this statement is because when I first started business Which was like 10 years ago. I had no one there to teach me There was no one the internet was not as there was no internet guru. There were no online courses Everyone that I talked to someone that is a 10 steps ahead of me. They're so far out of reach I can never connect with them. They think Mia is a nobody and no one was willing to lend a hand to me Which is a reason why now that I'm in a position to help I Want to be able to help you I want to be able to help other people out there To achieve and be the best versions of themselves because I understand the hardship that when no one is willing to lend a hand How difficult and how dark it really is Which is a now your turn to figure out your why? so the why statement template is to Something so that something to to and the contribution that you make to others What is it that you want to be able to do to others? What are the results and the impact of the contribution that you're gonna be able to make? What is that in? The link below you can download the worksheet template and we have much more instructions in helping you define Your why statement so go ahead download it and start working on it super crucial for your restaurant success journey Now that we figured out our why we're gonna be talking about vision and statement Oftentimes one of the biggest question that I get when it comes to these two topics is How are they even different? It seems like there's so many different overlaps and that's the reason why we're gonna be talking about the difference a Vision is where you want to be and a mission is how do you get to where you want to be and they work hand-in-hand? Vision is about your future a mission is about the present Leading to the future. It's much more action-orientated a Vision inspires you to give your best. It's an inspiration Oftentimes is an idea. It's a concept Whereas a mission becomes a roadmap to get to your vision Vision and the biggest differentiating of Them too is that vision is intangible. It's something that is up in the air once again It's a little bit of a concept up here Whereas a mission is something that I can measure. It is something that is tangible as An example Starbucks's vision is to establish Starbucks as the premier purveyor of the finest coffee in the world while maintaining our uncompromising Uncompromising principles while we grow. Yes, it might seem like whoa really fluffy. It's it's up there somewhere It's a really big concept that we can swallow It's a really big vision that someone has whereas mission is much more tangible to Inspire and nurture the human spirit one person one cup one neighborhood at a time So we can measure how they plan on attaining their vision. That's the difference between the two Now it is your turn to identify your why and to state your vision and mission statement and once again Go down there in the link below and download the worksheet follow through the steps to define that this becomes Your superpower whenever you have any problems come back to this worksheet And you're gonna be able to revitalize and to re-energize to go out there and fight What you've learned today is to discover your why your vision and mission statement so then that way you can defeat any hardship Knicks up. We're gonna be able to talk about and harnessed your three alter egos to set up your restaurant for success all of us have Three altered egos by identifying it being aware of it. We can harness all three of these powers I'll see you guys in the next module


Hey friends today, we are gonna kick off another epic Disney resort hopping staycation I am so excited for this. I know you guys enjoyed those videos and you enjoyed the sun rises So we're gonna do it again, and we're gonna stay at different resorts We haven't stayed at yet or different parts of resorts We've already done the Grand Floridian and we've done the Polynesian the boardwalk and the wilderness lodge. So Let's go do this and for our first night. We came back to the wilderness Lodge But we're staying in the Boulder Ridge Villas never stayed here before we stayed at Copper Creek last time So I'm excited to see what these rooms are like. I can tell you right now Boulder Ridge is definitely a lot more quiet and more secluded than Copper Creek is and it's actually a very beautiful Scenery around us. Oh, and I love the music. They're playing Last time we were staying at the wilderness Lodge We were actually staying at the Copper Creek Villas, which is right here and This time we're in the Boulder Ridge section And I asked for a room on the highest level and they actually gave me the fourth floor and the very last room at The end so we're pretty far away from actually all of the hustle bustle from the main resort And that's what I like and like I said normally if you're actually on vacation You wouldn't want to put in a request for the highest level and the farthest away But because this is a staycation and I'm gonna be focusing more on the resort That's how I like things and if you recall last time we explored over here I really fell in love with this lobby and now we get to stay here Look how beautiful. This is the music all the wood. It is such a gorgeous lobby look at all the way up and Also now that we're actually staying here We can spend some time in the Carolwood Pacific room and actually feel at home because we're staying here You know you visit the resorts all the time well I do and if I'm not staying here. I kind of don't feel comfortable, but when I'm staying here It's like I'm home So I can't wait to actually come down here and just relax and hang out with Walt's original train and just take in all of this beautiful resort But for now need to find the elevator so we can go check out our room and Right here are the elevators and they are fancy Wow I've never seen such a beautiful elevator door before The inside of that elevator is really nice, too. I mean wow this might be my favorite elevator Oh, I love the Grand Florida in one though. Oh, this is so exciting. I like these hallways as you can see Our room numbers four five six three. So we are the last room this way, please a Look down at this beautiful lobby Look at all of this woodwork and all the carpets, too We're at the top floor of this area and our room is actually down the hallway. This is really nifty Take a look at the hidden Mickey's up there. This is a really pretty resort. I have never been here before And here is our room like I said if you're on vacation You definitely don't want to ask for the farthest away room because that is a long walk and a day at the parts You're gonna feel it But I am all about the views from the balcony So usually the last room is always got good views So now let's check out the room. Oh This is nice I like it. Oh, I suppose we should just jump in and give you the grand tour Look at that door. That's the door to the bathroom. I like it. I'm gonna take a peek see inside Oh Nice little tub. They don't got the stand-up showers, but Can't have it all can you but I like this door and then we'll check out the little sink area Oh, that's me. Hi. I like these lamps and I also love the sink, too. It's like a little waterfall Now that's a fancy sink. Oh, I like it.  Oh Yeah, it's got all the extra pillows and all that good stuff not too deep. Oh wait, that is deep Holy moly Why they put so much Unused space back here. Look at how far away we are. This is like a home of their room I mean if you put down some pillows and a little blanket you can actually sleep in here I'm serious. Take a look at this It's huge and then we have the kitchen area with another closet Why do they have so much closet space in this room? I mean, this doesn't take you to Narnia or anything, but lots of closet space You can see you got the microwave the toaster the fridge Fully stocked and ready to go. I like it. Oh No French vanilla creamer Dang and now let's take a look at the sleeping arrangements I closed the curtain for the balcony because I want to show that last but take a look at this bed. I Love it.  I Don't know what this says. These are actually park line brochures. I like it Bay Lake Wonderland the villas in winter. This is really cool a Nice couch. This definitely pulls out Nice little coffee table, but I feel like something's missing The chairs are actually really really nice and heavy very sturdy But we're gonna have to pull these away because we've got to take a look at that bed in there It's always got a hidden treat and I can't wait to see it Okay, oh That is gorgeous.  I like this one. This one might be my favorite Wow, I Feel like they could have just probably put a table with some chairs there and just had this on its own It's not we didn't have to pull everything away to get to it But regardless it is such a nifty little treat. I love just checking these out They're like the highlight of the room. Oh, that's heavy Another nifty feature is this dresser Very nice dresser. I Always listen to the sound that the dressers make when they open can tell you a lot about it How good of a quality it is? This one glides very easily. Oh Yes, I like it. I Also like that mean light fixture up there, but now we have to get to the good stuff the balcony view You guys know I'm all about those views It's a good one It's a good one Just take a look at that Beautiful isn't it? nature surrounding us Nothing to see even on this side. Oh Wow, this is gonna be beautiful and I'm pretty sure the sunrise actually happens right there So we're gonna get a good spot of it, but it's gonna be hard to clear those tree lines, but it's still beautiful I love it here. You can look where the farthest all the way down The patio furniture is pretty nice Oh metal metal and it's not that big Actually, the closet is longer than the the balcony. It's a little strange. I could lay down out here They actually used to have a walkway that you can take over to Fort Wilderness and it actually was right there That's no longer actually open and I was thinking about maybe taking the trip over to Fort Wilderness and see what kind of food They have since I've already eaten at most of the locations here at the Wilderness Lodge I thought that would be fun. So we're gonna explore options and how we get over there and see what they have to open too So now we got all settled in got my face mask on gonna grab a Bud Light We're gonna hit the road and see about getting on over to Fort Wilderness. I'm excited to get there I haven't been there yet since it's actually reopened. It'd be good to see something different Also want to point out they got promotes Properly cleaned and sanitized plus one of those fancy Blu-ray players And I have some great news because I found out that PJ's takeout window at Fort Wilderness is open and Crockets Tavern so PJ's actually sells the same ribs and chicken as Trails End and Hooptie do So we're gonna get some ribs and chicken and probably some moonshine from the Tavern. I'm excited The bad news is the boat is not running So we're gonna actually have to take a bus which I don't mind I like buses Oh, yeah, right here take a bus, but it's definitely gonna take us a little bit longer to get there When we used to be able to just take the boat and then be right there. I'm gonna have to go all the way around Seriously though when you're walking through here and this music's on It's so great Look at those views. I Just love the music I've never actually taken a bus from here to the Fort Wilderness campgrounds before so I don't know if they have a quicker way Or if we actually have to go through the whole entire resort loop that they have there Either way it has been a long time since I've been on a Disney bus So I think I'm actually gonna enjoy this and it looks like we got the Daisy bus Can't come in ah We have to get in on this side Just me Let's sit right here. Sounds good Holy moly They actually do have a quicker way to get here because I was literally just sitting there I looked out at my phone for a second and we're here That to me is absolutely mind-blowing it literally took like two minutes to get from Wilderness Lodge Over to Fort Wilderness by bus usually they take you back out on world drive And you have to go all the way around. That was awesome. It's so strange seeing Fort Wilderness like this. I Like the music though Pioneer Hall where Hootie do would normally be there would be tons of people out here at this time It's just me Just little old me and this is where trails end would be and like I said Crockett's Tavern is open We can mobile order food Actually from PJ's so we're probably gonna do that and then eat in Crockett's. I like that idea They cleared out all the bar stools and they have some tables here But I'm interested in the moonshine drinks all of their drinks actually are served with moonshine You can get other things too, but that's what they're known for I like it and I think a moonshine mojito is catching my fancy hair that looks really delicious Or the gullywamper These are some really awesome mixed drinks and I like that it's actually different than all the other resorts because like I said They use moonshine here Thank you, you've got it and take a look at that guys now That's a moonshine mojito. I don't think I've ever had a moonshine mojito, but I do love mojitos You can actually drink in the tavern itself They have all these tables actually set to the side and socially distanced, but since I'm at Fort Wilderness I'm gonna go sit in the rocking chairs and enjoy my moonshine just like an old-timer would They got some really nifty looking rocking chairs, and it's a nice view too Usually you would see a lot of horses, but I don't think the horses are out and about now I'm curious on how this is gonna taste because they are known for making very strong drinks here But we're gonna give it a go delicious Mojitos are so refreshing Now we're just gonna kind of chill out relax I like it This is seriously so peaceful and relaxing. I absolutely love this spot But now let's put our food in at PJs So then that way once we finish our drink it'll actually be ready and we can start eating I am probably just in a mobile order, but since PJs has this like nifty large menu I'm gonna show it to you guys because it's probably easy to read I'm more than likely gonna get the ribs and chicken combo for $24.99 I don't think I need a full slab and eight pieces of chicken, but that's a good deal for $44.99 And then they got pizzas and burgers and pulled pork all the good stuff even some snacks Oh, I like snacks And the chicken and rib combo actually comes with two sides You can choose from mac and cheese, mashed potatoes, cowboy beans, french fries So I decided to get fries and cowboy beans You know, I wanted the beans because kind of felt like I was a little bit in a western so Ward to the wise though If you get this drink Take your time with it because it is very strong And I just got the notification that our chicken and ribs is ready I'm so excited. I'm actually really hungry if you're not familiar where PJs is It's actually in trails end Like you actually go to the buffet and pick up your food right now There's no food on the buffet and it's kind of just like an open area But this is where we're gonna pick up our food This is huge. What did I order here? So now we're gonna find ourselves a table and this is all the dining for actual trails end Oh, let's sit over here Yeah, I like this little corner spot. Hello friend So I kind of perceived that wrong I thought this was kind of like just an entree of ribs and chicken This is a family meal Holy moly guys I have so much food. Wait till you see this This is happening here guys. This is a lot of food Wow, I don't even think I'm gonna finish this all because this is way too much Who am I kidding? I'm gonna probably finish it Let's take a look in this mystery box first. You can see we got chicken and ribs all in there and then this box was the french fries and then The cowboy beans and then I'm guessing this is barbecue sauce because The ribs are actually aren't sourced. So we're gonna have to change that I'm gonna take out the chicken put it in the french fry box Oh, yeah, just like this. This is still a lot of food Okay, and now we have the ribs right in there What am I doing?  I just like them because they're easy to eat But uh, I'm excited. This is good chicken. This is the same chicken at Hootie do and at trails end That is so delicious. And then take a look at the cornbread like they give you a whole entire loaf Holy moly And then the baked beans That is way too much baked beans. Well, it's family size. I just didn't know but these are delicious There's no way I'm gonna be able to eat this whole container of beans. So some of this is going home with me or back to the room But let's get down to business And I mean rib business And I'm probably not gonna record anything After I eat these because I have to leave and go wash my hands I don't want to get barbecue sauce all over the camera, but these look fantastic I don't even know how to approach this, but I'm just taking the whole rack out I'm just gonna take the whole rack out. Maybe just pull one off. Oh, wow That's oh boy.   Can we just take a second and appreciate that sunset that's happening right over there? That is beautiful, isn't it? I love this whole entire resort over here. It's just so beautiful and I love the music too But we need to head back because we're also staying at a beautiful resort So we're gonna head back to our room. I gotta find a bus I hopefully don't have to wait long because that was the only one that was waiting to come over here I might be the only person that's waiting to go back And would you look at that the new tricycle d ranch? I haven't been over here to see this yet, but this is beautiful. It used to be right here Look at that sunset. Holy moly But that is unbelievable. I love it. It looks so great and I could see a little white horse just sitting there right now It is closed right now, but I'm definitely coming back I'm coming back Not alone this time, but I really like these new buses They got kind of like a wood floor That's pretty fancy And now we're back literally probably took Two minutes. I love the bus transportation. I thought it was going to be a couple minutes Like I thought like maybe 20 minutes, but this is really awesome. And I like seeing all these lights on It's like a new experience And now we're back at the fancy elevators You look at that And guys, I am so full right now Honestly, that is such an amazing deal for family.  I didn't finish the beans or the cornbread or the fries And I didn't feel like bringing them back. So I just tossed them I wish I would have known I would have gotten the smaller meal, but next time I do know So now I'm back in the room. Ooh, my glasses are reflecting the resort tv You hear the music? Now I'm just gonna hang out on the balcony relax And calm myself down before I actually have to head to bed I don't normally go to bed this early, but when I'm staying at resorts We gotta wake up and uh have coffee and sunrise time because I love that It's just really fun. And I think this one's gonna be a good one So I'll make myself go to bed early for that But just a quick pillow count looks like we've got four pillows The Polynesians still the champion six pillows. They left me plus the backups in the closet And I think I'm gonna let the tv just keep on playing Maybe turn it down a little bit, but falling asleep to soaring doesn't sound like a bad idea So, uh, we'll see you in the morning Good night And good morning Time for coffee and a little bit of sunrise I like that I woke up a little bit later than I normally do and it's actually starting to get light out So we're gonna have to hurry up here I forgot the french vanilla creamer Tiss tiss Oh, wow Oh, yeah, this is looking beautiful here guys I'm so excited You might say that the true life adventures began with a little deer named Bambi Walt Disney had purchased some film of a fawn in its natural state For his animators to study for their Bambi animation But Walt saw something else and one thing has always led to another here and Bambi was no exception Oh Well, that was nice and relaxing very peaceful, I love it here the sunrise I couldn't get the actual sun because we weren't high enough over the tree levels So it was actually peeking through the trees what I thought was actually kind of pretty But it is just beautiful over here I love all of the views and the nature and the different types of trees. It's really relaxing balcony You can see the cabins right through all those trees there. They kind of look cool like that And it's just very nice, isn't it? See we're still waiting for that sun to actually peek over the tree line And it's almost eight o'clock. So I've been out here for two hours Definitely worth it though All right Well, I'm gonna pour myself my second cup of coffee in the morning. I need two or three usually And I'm gonna take it down to the carowood pacific room and uh Kind of just hang out in front of the fireplace look at Walt Disney stuff and Sit in the rocking chairs. I like that idea Might be the only person down here already. I would think this is like a hot spot. Oh listen to that music And of course, we do have to take a look at all of the cool disney history down here I pointed out before that this is Walt's train that he actually had in his backyard Walt two pieces of it. Still that's an amazing thing and there's actual pictures All around of Walt Disney just enjoying his love for trains These are all amazing I just love old disney history It's so amazing. He was such a great man And with that, I think I'm done here Thank you so much to my buddy Matt and the rest of the cool family They had points left over. So the reason that I'm staying here They ended up giving me those points and very nice of them like honestly I'm very grateful to anything that I ever received. So thank you guys. Thank you to the cool family And I hope you guys enjoyed the video. I enjoyed making them. So We'll see you next time. Bye


And the Nigerian Governors Forum says the plateau state killings were barbaric and senseless. The governors have also called on security organizations to fish out all of those involved and bring them forward to face the law. They believed this will deter other persons planning attacks of such nature. The governors have also urged aggrieved ethnic nationalities and their militia to avoid needless reprisal attacks.


Abstract the COVID-19 pandemic comes across the gradual rise of the influenza virus, and the co-circulation of the two viruses is inevitable. The dangers of co-infection are becoming clearer, but the disease burden of co-circulation in the near further is unknown. In the intersection era of big data and machine learning development, it is important to distinguish the impact factors of co-prevalence and apply appropriate methods to advance projecting future risks. This article was authored by Jingyi Liang, Zhichizeng, Qianying Li, and others.