the Rutherford Hartree-Fock equation let me just quickly derive it again for continuity. So we had we started from the canonical Hartree-Fock equation which was in space orbitals. So I hope all of you can write the equation in space orbitals. So let us assume that the phi i's are the space orbitals and our chi's are the spin orbitals. So this is the canonical Hartree-Fock equation for in space orbitals and in particular if it is closed shell. So of course this form will depend on what kind of system it is. So this is a particularly for closed shell you can get a single Eigen value equation like this where f of r or f of r1 is h of r1. Please remember that now the spin is integrated. So this is only in terms of space orbitals. So this is the spin integrated equation for the closed shell. So h of r1 plus sum over j equal to 1 to n by 2 integral phi j star 2 1 by r12 2 minus p12 phi j2 d tau. So I hope all of you can write this 2 is essentially r2 just to make sure that you understand and the integration is done over d tau 2. r12 is of course mod r1 minus r2. So this 2 comes first of all the summation is over only n by 2 special orbitals. 2 comes because of the fact that the electron which is giving interaction can if this is an up spin it can be either up spin or down spin for coulomb and for exchange it can be only parallel spin. So there is only one term. The p12 will ensure the interchange of r1 and r2 when this operator will act on the coordinate of electron 1. So when it acts on the coordinate of electron 1 it will ensure that this becomes 1 and this one will become 2. So that will bring the exchange effect which cannot be classically interpreted but otherwise everything is exactly same as the Hartree-Fock equation for spin orbitals. So this is what we first did then we said that for molecules the exact solution of this is difficult so one has to adopt what is called the expansion in terms of a basis. So instead of solving this equation in the coordinate space we solve by expanding these special orbitals in terms of a basis because these are now my unknowns the special orbitals and the basis is a set of known functions. So the unknowns will become the expansion of the coefficients so these are basically numbers so that is the difference. So we can write now phi i of r or r1 it does not matter it is a dummy variable sum over mu C mu i and a basis which is the basis usually of atomic orbitals but it need not be so usually the basis is of atomic orbital the set mu is a set of atomic orbitals but note that this is only usually mathematically of course it can be any complete set but of course the chemistry dictates that if you have a set of atomic orbitals this becomes convergent. Since you are expanding in a basis of course there is a problem of basis set limit and usually again we cannot reach the limit unless we take infinite number of functions but let us assume that we have taken an m basis function. So in which case the Hartree-Fock itself was an approximation has one more level of approximation that is the expansion of the basis is it clear? So that is what we did and then we said that this problem now which was a problem of finding a function set of n by 2 functions is now reduced to finding a set of coefficients because these are known functions and those coefficients are obtained by the Hartree-Fock-Ruthan equation by plugging this into this equation and multiplying the equation by a member of the basis conjugate of a member of the basis and integrating over R. So that led us to the Ruthan equation which I just write this first and then explain sum over mu equal to epsilon i sum over mu S nu mu C mu i where F nu mu was a matrix element of phi nu star R F of R phi mu R d of R d tau. So when I do the integration multiply by one member of the basis and integrate the integration is of course a definite integral so it will result in a number that number will depend on the mu here and mu here so we call this F nu mu and this is actually has a structure of a matrix m by m matrix because there is a m in number so you have an m by m matrix. The C mu i's are very clear they are the coefficients of expansion of the ith what I now call molecular orbital in terms of the mu ith atomic orbital so in a very simple chemistry notation C mu i is the contribution of mu ith atomic orbital in ith molecular orbital so that is what this coefficient means right that I expand the ith molecular orbital a mu this is leading to this coefficient so this is the expansion of a mu in phi i so this is basically famously can be called your LCAO-MO coefficients so if you want to track a molecular orbital all you have to look is the ith column please note again the way the symbol that is written is a standard symbol where the molecular orbital is expanded in terms of a column so that is why it is not C i mu but C mu i so if i is 1 this is 1 1 2 1 3 1 4 1 up to capital M 1 so the first column will give you the expansion of first molecular orbital in terms of the M AO second column will give you expansion of second molecular orbital and so on so that is a standard notation so please remember it is used in all Hartree-Fock programs and this is the standard notation you can of course do it the other way round the row wise but this is the standard notation so C mu i is the coefficients S mu mu is similarly an overlap integral between phi mu star r phi mu r d tau and d tau and if these are not orthonormal of course the S mu mu will not be delta so provided of course they are orthonormal this will become a delta mu mu chronicle delta which is orthonormal set but in general they are not so the equation that you get is of this form and which you have derived it is very easy to do this just expand these integrate by phi mu star Mu star oh sorry sorry I think there is a mistake yeah I think you should have pointed out these are all A these are expanded in terms of the basis Nu star Mu nu star sorry so when I expand this in terms of the atomic orbital basis and multiply by Nu star then obviously you will get Nu star f of r Mu r so not the phi phi's are no longer there okay so these are all in terms of the basis okay and C mu i is the expansion of phi i in the basis of Mu okay so this is the famous Hartree-Fock-Ruthan equation okay we have to solve this equation clearly clearly if and this is something that you should recognize if S nu mu were delta nu mu which means if the basis were orthonormal okay you could see that this equation would have become f nu mu C mu i and here you would have got nu equal to mu so it would have become epsilon i C nu i for a specific nu where nu is specific you are summing over mu and this would actually have been what would I would call now Eigen value equation so all of you know that this is in the structure of an Eigen value equation so this would have reduced to an Eigen value equation provided S mu nu were delta nu mu but in general they are not so we must recognize that in gen this is not a general form this is the general form of the Routhan equation okay clearly then our next task is to find out the C mu i and to do that you have to write f nu mu in greater details by going to this equation integrating writing this in terms of the coefficients quite clearly if you notice that since f depends on the orbitals when I expand these orbitals the capital F nu mu will also depend on the coefficients and this is where the whole self consistent field structure which was there would again come back here because f will depend on the coefficients so whichever way you solve the equations you have to solve iterative so there are two problems one is of course iterative problem which is already half that is not vanishing that is there it is only that the iterative solution will now be in the coefficients but a further problem that is coming is how do you solve this equation so how to solve because it is no longer Eigen value equation so both there are apart from these there is a second level of problem that we have now encountered since it is not an Eigen value equation so how do I solve the Eigen value equation okay so we will come to that later but right now I hope all of you should be able to write f nu mu so f nu mu is if you start with this it will be integral a nu star r or r1 see please remember that whether I am writing r or r1 it does not matter because that is a integral which is integrated over the element so this is just a dummy variable I am writing r1 here specifically because I have to bring in r2 so it is easy to see 1 and 2 if I write that r then if I call that r1 then it is more difficult to write this I have to specifically write r minus r1 modulus r minus r1 so I am just avoiding doing that so whenever I require I am writing this r1 but it does not matter because that is a dummy variable so a mu r1 theta 1 so that is the first term now note that this can be trivially integrated because I know the operator h of r1 these are my known basis functions so I can integrate for whichever integration may be very complex mathematically complex but this is doable then the second term comes from here the second terms are more complicated because you have a sum over j 1 to n by 2 first and then there is an integration over d tau 2 and there is a further integration over d tau 1 please remember I am eventually doing an integration over d tau 1 right that is my f mu but in the definition of f of r1 there is another integration over d tau 2 I hope you can see that right so eventually there will be double integration so let me write it down carefully first I write a nu star r1 which is just comes here because I want to write this as a nu star f of r then instead of r now I am using r1 that is all this is dummy variable and there is a sum over j which I have just deliberately taken outside then I have a phi j star r2 so I have to write phi j star r2 again as a expansion in terms of the basis so the same expansion I am going to use now for phi j star so I hope you can expand this phi j so let us use different dummy variable all you have to do is to be careful about dummy variable so I cannot use mu and nu they are already taken so I must use something else so let us say I write phi j as sum over lambda c lambda j just I am writing it on the side line c lambda j a lambda so I just wrote it in the side line so that it becomes very easy whether it is r1 r2 that depends on what is there so I now have to do phi j star r2 so I have to write this as a lambda star r2 and of course there is a c lambda j so c lambda j star let me write it here outside the integration because that is the number so that comes outside the integration then you have 1 by r1 r2 and I will keep using the abstract form for the time being 2 minus p1 2 and then let me integrate the d tau 2 by putting in another phi j remember this is again a phi j but I cannot use the same dummy variable I must use another dummy variable let us say sigma so I put the sum over lambda of course already come and then I have a sum over sigma so c sigma j now c sigma j is already written so a sigma of r2 so I am expanding this in terms of sigma this phi j r2 so I have a c sigma j which I have written outside the integration and a sigma r2 and of course I must complete this by bringing in a mu r1 and now I have d tau 1 d tau 2 first and then d tau 1 is it clear I hope all of you can write this yes. So summation over lambda sigma summation over j c lambda j star c sigma j and this integration now if you look at this entire equation they are all numbers because the first term is the number of course the second term is also a number now because it is a total integration of d tau 2 and d tau 1 unlike here where there is a partial integration of a d tau 2 it has a both the integration and which is expected because from this partial integration I did a further integration of d tau 1 or d tau whatever so obviously this should become a number and I get a very compact form of what I call f mu out of which this is trivial but now this is where the problem will come because to define f mu mu mu you can see that I require the coefficients. So that is the reason again you have to do an iterative or self consistent field solution so instead of guessing the phi I have to guess the coefficients because these are my unknowns not the phi because these are known and then I have to construct the Fock matrix and then somehow solve this equation which I will come later how to solve so let us not worry right now let us say I solve this equation get the coefficients reconstruct the Fock matrix and keep doing till it converges so that will be my strategy now so instead of strategy of converging on phi I am going to converge on coefficients now there are several questions what do you mean by convergence when do I say it is converge all that I will discuss when we go into more details but philosophically that is going to be the strategy now so basically guess the coefficients guess the coefficients see me y matrix then construct the Fock matrix solve Routhan equation get a new set of coefficients let us say I call it so let us say I start with some n I call this n plus 1, n is number of iteration. Mathematically I am just writing n plus 1 and then go back and construct the Routhan equation again a F again and keep solving till it converges it comes out at the convergence point which I will discuss how do you convert but philosophically that would become your mathematical way of solving this so reconstruct after the coefficient the Fock matrix solve this equation Routhan equation again keep doing when the coefficients converge and what do you mean by convergence we will discuss later but there are several things to discuss before that one is to first of all look at this equation very carefully the Fock matrix equation very carefully then to see how to solve it this equation because as I said they are not orthonormal so it is not an eigenvalue equation so we will have to do piece by piece so let us look at this part little bit more carefully the part of the F nu mu which includes the two electron integration but before that let me write down the first part just as I wrote F nu mu I can now define integral a nu star R1 or R does not matter h of R1 a mu of R1 that is the easy part and that is very often called the h core sorry h core nu mu it is again a matrix element right depending on the basis nu and mu and this is very often called the h core now it is actually capital H but please remember this is not a Hamiltonian full Hamiltonian it is just the one electron part and it is very often written as capital now and with a core on the superscript the core essentially means that it is the one electron part the kinetic energy in the electron nuclear attraction so that is all the core has no other meaning so basically it means a one electron part somehow it is traditionally written with the capital H I could have written a small h just to continue that but that that should not bother you okay so this is what I define the d tau d tau 1 of course this is the first part of the F mu mu okay then the second part before I come to the second part I must remember that there is a P12 here of course so there is a Coulomb and exchange part so that of course I should not forget so the Coulomb part and exchange part both involves integration of this kind a nu star R1 so let me write those integral first a lambda star R2 so one of the typical integral don't worry about the 2 minus P12 but what is important is 1 by R12 so let me write down those integral a sigma R2 and a nu mu R1 d tau 2 d tau 1 this is the typical form of the integral that I must first understand because after that it is only a question of multiplication of 2 and when I exchange 1 2 it just exchanges these two but that doesn't harm and that that is that is only index change in this case so this is what is called the two electron integrals and the h core just as just as I written this these are called one electron integrals of course it is very easy to understand why they are one electron and they are two electron one electron integrals of course involves the kinetic energy plus the electron nuclear attraction the two electron is just the two electron integrals and that is very important to understand these integrals of course during the SCF process have to be calculated only once because you can imagine that the basis sets are known functions are known so I just calculate once the iteration comes because they will be multiplied by these coefficients all right but these integrals per se has to be evaluated only once okay so these integrals are very important they are they have a nu and lambda on one side sigma and mu on the another side so just as we have been doing the Dirac notation I can write this integral in Dirac notation as nu lambda right 1 by r12 sigma mu sorry mu sigma okay by the Dirac notation it is a 1 2 1 2 notation so so I just want to tell you again just as we did for the for the ijkl in spin orbital space orbital I am going to use a simple notation like these two write the full integral so I am not going to write the full notation okay so then I should be able to write this part of the fork matrix very quickly so then I can write this fork matrix now f nu mu as h core nu mu plus lambda sigma sum over j c lambda j star c sigma j okay so this part I bring in and now I write the integral so the integral will be first integral will be nu lambda 1 by r12 mu sigma however multiplied by 2 okay because you have two times this okay minus so let me write this over with the bracket minus the the term which is comes with only one but there is a p12 so it will only exchange the right side so now it will look like nu lambda 1 by r12 sigma mu that is it so your fork matrix is now written correct and you can actually now construct the entire fork matrix because these are now numbers everything in numbers so that is why we say in high performance computing despite the fact that everything was a function of r dependent finally everything becomes a number it just manipulation of numbers matrices and numbers it becomes very easy but big big numbers because remember these are no longer depends on number of electrons these dimensions depends on the capital M right you remember my phi i's for phi j's were expanded in a basis and the basis I said should be as complete as possible even though my number of electrons may be 2 4 10 whatever my basis has to be very large so the capital M was much larger than capital N so these are basically m to the power 4 in number 1 m 2 m 3 m 4 m so m into m into m into m 4 m to the power 4 and you can imagine per se these integrals are very large of course these are not any separate integrals remember these integrals and these integrals are same it just subset is different instead of so it's time to the power 4 I don't have m to the power 4 is a really very large number you can see very quickly typically today if you use a basis of 100 you can imagine what is 100 to the power 4 you're talking of you know 100 million and and later on I will mention this is the problem of high performance computing so a lot of good computer science people can help us they know how to do really so there's a those who are doing programming coding they can be actually they are they take a lot of interest because they have interest in computer science you know many of them are just good coders and and good algorithms matrix eigenvalue equation involving large numbers eventually you are forming a m by a matrix remember using data which are m to the power 4 so some summations are there okay and there is a summation over j of course which is 1 to n by 2 let me mention this and this is these are m 1 to m just to understand because these are only over the molecular orbitals so they are n by 2 and that is where the scf part will come the coefficients okay so they are molecular orbital but these numbers are actually called m to the power 4 and and something that can be quite you know difficult to handle if you don't do it properly fortunately and I will come later on the computation part many of these integrals are many times 0 fortunately because of either symmetry in the molecule depending on how you choose your basis if you cleverly choose your basis you can make many of them 0 and that is where group theory is very helpful you know those who have done group theory course would actually appreciate that this is also basically these bases have to be some kind of symmetry functions of 1 by r 1 2 and then it can be 0 so although they are m to the power 4 in number they are sparse I hope all of you heard the word sparse sparse matrix means it's a matrix but most of them are 0 there are very few non-zero so this is called sparse matrix so maybe typically for a very symmetric molecule only 3 to 4 percent may be non-zero it can be that sparse okay so you have to be you have to be clever in not unnecessarily playing with zeros because you can you can keep on multiplying you will see that you have to multiply these times these so what is the point in multiplying 0 and wasting computer time so instead you have to be clever in picking up only non-zero elements and then doing this summation now that is another issue that we will not discuss today how to do the summation because if you if you drive by the loop lambda sigma then quite clearly many zeros will come unnecessarily and you keep keep multiplying on the other hand what is done is what is called integral driven programs where you take only non-zero integrals and then do the multiplication but then the question is how do you multiply because you don't have loops here so you look at what are the values they also stored not only non-zero values but they also store these indices only for those non-zero values once I fetch the indices I know where it will go so you know it's a like a table table it's very easy to do if you are of course if you have ever done programming you realize that it's a you know it's something that the computer science people if you just tell them they will be excited so it's very exciting actually the programming part itself is very exciting but remember you can't do I have a loop driven program that is wasting the time because too much too many things are 0 so they do what is called integral driven programs non-zero integral driven programs so you only say you only store non-zero integrals and drive the entire program only through them so that is a strategy that we will not discuss today but I just thought I will tell you


David Allen, I sent you an email. How's it going, buddy? Do you have anything to say about Ave? Yes, so Stani, I Think I was called Stani the genius that guy and I've talked to him before I like where Ave is going I like the whole decentralized and actually hold I Own and still hold Ave. I never sold it I think it could be a big portion in the DeFi player as you know as we see like different DeFi progress just crash and burn But only time will tell so if it's me I'm gonna actually start picking up more more obvix I think it's undervalued, but that's it Nice glasses. Thanks. I wear these glasses because sometimes my eyes get stressed out and they go a little cross So I wear these so I don't get headaches and stuff like that Some different about your face you shaved. Yes, I shaved. I look like it The problem with the shaving is my head looks even bigger. So I don't know how that worked out What's your thoughts on pulse chain? I don't know. I know it's that Richard Hart, Dealey and I know you have to sacrifice your Ethereum. I know you get you get pulse chain That's all I know don't understand it probably want to best into it unless I understand it And that's it Who J. Chersen I'm being this month. I'm in sweat. Sure awesome And that's just it like I got a lot of people following. So if you beat me then send me a screenshot And we'll go there What do I think about stepping I don't like stepping at all so I know people love it and That's that's for you for me like some people worked out pretty well They got an earlier they got in and they they they picked the rights NFT I must just pick the worst NFT of all time because all I do is repair those damn shoes And that's it and then some people say well, you didn't you didn't level up the right way You should have done more in the resilience and and and not picked on luck I didn't pick that much in luck. So I'm gonna give another chance I'm gonna sell that NFT when I get around to it and then buy another one, but I got to tell you Buying an NFT for a thousand two thousand dollars and hopefully breaking even hopefully I Just don't see that now Maybe when everything comes in where stepping it allows people to rent your shoes. I can see it right now It's not there.  So maybe I just did it wrong. I'm gonna try again from scratch go from there But that's why I'm not a big fan. All right Crypto rocker says you should start doing portfolio reviews. Anyway, that's a good idea Tell you something we have going on an opportunity. So I used to do that all the time We still on Fridays and then I just got away from it because it's It's tricky because you got a you know Sometimes you have to dash some people's dreams And crush their crush their souls and tell them it's not a but again, like I'm just kidding I just I can't give you much of any advice I can just tell you only tell you what I would do if that was my portfolio But it is fun and a lot of people I must tell you when we did portfolio reviews the majority They were pretty smart reviews and and are pretty smart portfolios and they would diversify adequately and I had a good time doing it So probably do it again. Oh great question. So sim says do I know where to buy gold go see my brother in Las Vegas That's all he buys. He has physical gold in his house I told him by Bitcoin and he didn't and an actuality. He did pretty good because I told him to buy in January and Actually did he did better, but in the long run. We'll see I buy gold in my I trust Roth IRA account Which is I think a pretty good hedge against everything else that I have which is Bitcoin Ethereum Chain link and Cardano and a bunch of other things that are in there ready. So that's where I buy gold, but That's it Please can you summarize to us? They're just coming here, please bottom indicator Haven't been since March 2020 Probably not the bottom because no one can predict it. I talked about PO AP or PO app It's free minting of NFTs for the mentor and the minty The people that actually created and the people you give it to and it's good for People who come to your events and then lastly Sweat coin is gonna be the biggest total generation event of all time in crypto. There you go I'm investing in rug pull coin. Well, that's a lot of one DeFi take your pick not a big fan Rob my birthday is May 29th and the biggest fan of you and James best you two is this crypto game You've both here, but we try David. We try Alright, we do try Yeah, and then That's a good name priapism If you don't know what priapism is you can you can Google it pretty good and this is DCA Look look 10 years ahead. That's right You know what that's it. I mean if people just have that that outlook You know what and I'm glad you're here. All you guys are here because Here's the thing let me back up for a second get my head out of the shot. Here's the thing like I For In may 2021 April may I had to deal with a bunch of tourists in the in crypto crypto bill and I try to be a good guide and be very patient with them but they were just annoying And now that you're now the tourists are gone And I got more of the level-headed people people like yourselves who are here and they get it and they take Responsibility for their actions. It's a hell a lot easier. I get a lot less views. I just do not care It's just great to talk to people where it's like Oh, Rob, you didn't absolutely break me because you talked about ethereum one day or something like that. So If you guys have If you're here now you have a better outlook of the Of the cryptoverse and where things are going and we know that It it doesn't matter the day-to-day or the six month frame or the year or the year over year It's really if we take a look at you know one year three year five years 10 years outlook This is the biggest asymmetrical bet you can possibly get there's a lot of losers out there But you don't have to it doesn't matter. You don't have to hit all the winners in a row Just give me one and that's all I need. So that's what's up. So thanks. That's vca When mullet saying thanks, man hit the like and subscribe best moderator ever or one of the best moderators Oh Seth thanks for coming in Yeah, we usually do it around this time Sunday's a little bit different And I got some drinking to do later. So it's kind of important that I get this done now Wenjo Rogan, that's not for me, man. That's for that's for people who are who are way way up there in the space Pretty cool, man. Not not really cool. Never been cool I just try to do my best utility is king exactly right What's this say? Oh, it's pretty smart Well, as he says if your time horizon is five or ten years, you'll be very happy. We just did this this Wait, I've been talking this like the last three days now Swish swish swish Swiss fund manager. I forgot the name They are a half a trillion dollar asset under management company and they have been talking about They're gonna just get in the cryptocurrency now and they said that our outlook is 10 years And we know that if we get in now, this is the time to do it and I'm like, yes, exactly and uh, and You're you're you're going to see other people get in now And it's going to be like a quiet type of thing and I really make a big deal about it They're gonna say well, we're we're dabbling in crypto.  Although in a couple years 3 trillion. I don't think we'll look like much of all so, yeah How is it Italy is awesome I wasn't a fan of venice Hold on. Let me say that again. I wasn't a fan of venice food. There we go a lot of seafood I'm not a big seafood guy. So that was the thing but I mean Oh, and I I don't want to ruffle any feathers But I wasn't impressed with the with the food in Italy and the reason why I was impressed the food in Italy is because I went to all the wrong restaurants, which is all the tourist traps. So when I go next time, I'm going to actually ask for reviews before I Stupidly go to different places. So yeah Do you like buckies? So if you're talking about the gas station, yes, it's the best thing of all time They're all the way through the midwest in texas It's awesome if you're traveling which I will be traveling from El Paso to Austin for that consensus in my sweet Dodge grand caravan minivan because I'm a baller. I'll probably stop in at buckies. So I'll see you there Yeah, exactly Oh Great question cosmos eta or dot who was the best tech I'm going to give you a lame answer. I'm going to give you a good answer lame answer is I don't really care and I invest in all three the good answer is that this cosmos first of all luna Wasn't their own was built on cosmos and it worked out pretty well Crypto.com their crow coin is built on cosmos cosmos is great for interoperability. I think we'll do fantastic Cardano, I'm a big fan of which I think we all know I also got a cardinal stake pool and the longer that we're into it The longer that I'm into crypto The more that I see that these projects that take things slow and really go a little like a snail's pace sometimes And some that people might say is a boomer coin, which is bitcoin Are the are the best bets in the long run?  I don't get that anymore So everybody got rug pulled. Sorry. That's just how it is. So ada. I can see and polka dot I mean dr. Gavin would he was a part of that like I like I call the ethereum mafia Which were the people that actually built the ethereum the talak and charles and and gavin You can't bet against polka dot. I think it'll be pretty big The thing is is that it's great tech The question is how does it get out there? And how does it get to make this these huge communities and how does it actually get to the next level? That's why I'm always talk. Let me show you. That's why I'm always talking about this And I'm going to keep talking about this community utility team in tokenomics Community utility team tokenomics if you have a built-in community like we talked about With the with the djm plays the genso's the everdome is the fame and now sweat coin It's the easiest thing of all time. So why wouldn't I do that? I got the wrong one. Sorry Share my screen This one. Sorry Showing you pictures of my wife Again, so everdome of fame. So again, the community is what makes it go And if without the community it's it's not going to happen unless it is just some of the most fantastic thing of all time But the community makes things strong the community pushes it in there and the community gets it in the public consciousness To where it actually blows up. That's what I'm going for from now on With exceptions exceptions every rule. All right Ah, let me get out of here That's right, man But it's an illness strengthen numbers. Good enough Where is this just by just by eith. Yeah I got to tell you between us Just me and you and the other couple thousand people that are here. I think people make investing Way more difficult than it has to be because if it's difficult for you Means you have to rely on them to teach you how to do something. It's to me. It's super simple it's just find a project that Has a good community does real utility has been around for a long time has battle tested and You believe in and just the best in that and then go from there And just dollar cost average and make it simple I don't know. It's like i'm taking crazy pills or something I'd show a pixel in my eye, but everyone's already seen our normally fans. He's lucky lucky devil so Surhindra ready nailed it dandy of icp or near in your product portfolio. I have near Uh insane clown posse. Just kidding. Uh internet computer protocol. I do not I think I did buy it, but I did sell it at a loss. I think it's ahead of its time Like teslae. That's right Algo is another one algos in my portfolio James d metaverse big plays coming up Um, I bought a lot of land and a lot of different metaverses and I like the land play I know doesn't make sense to some to some of you actually that makes no sense I get it right But I've done pretty well in the investments in physical land And I see things going into the digital world. So why not have digital land? It won't make sense now I think it'll make sense later just like trying to explain The internet the kids back in the the 80s like that doesn't make any sense. I have a dewy decimal system I don't need to find a book I don't know man. Stay far from it's hilarious. Stay far from nearest him. Oh, there is one thing I need to talk to you about about sweat coin, which thanks them for bringing this up. Let me share this Where did it go? Son of a gun There is something that concerns me And I thought it was a concern that I thought this could actually be Uh An asset So if we're on the sweat economy Their partners are spartan okay x blockchain electric capital jump. Okay gsr. Jordan Wagner near foundation. So it's built on near Sweat coins will be built on near transactions per second are very fast very stable so far We'll see if it can hold up to the scrutiny. But if you've got 75 million plus people coming in I guarantee these guys stress tested near. We'll see Sandeep now. Well and dope one So someone brought this to my attention that doesn't this concern you that dope one is an as a partner or an advisor first of all It's on the website So it is a little concerning They haven't taken it down yet. The second is maybe they don't want to take it down. Maybe The person to learn from mistakes are the people that made huge mistakes, right?  So Maybe in all honesty, they're like dope one, you know The visor sure I mean you still have technical knowledge. You still know how to build these things So what can we learn from you? I think actually it might be a smart move. All right Ah Right, what are we? Yeah, see osa. I've been in a sweat coin for two years now. Yeah And I think that's it Oh crypto your eyes out kid Uh Zoolander baby All right, that's it. No, no, we got a couple of minutes couple of minutes. I'd like to go I'd like to answer the questions as much as I can Like marriage counseling for a priest. I've never heard that before but it does make sense Rob, I'd like your thoughts on buying blue chip NFTs apes mutants It's not my realm man Um, I'll tell you what I know And I'll tell you what I think I know I'll tell you what I don't know so to get into these plays It might be a great opportunity because I know that these I I'm 99% sure these are all down with the rest of the market and it might be something to do um But some people don't understand the whole process of NFTs and what makes them actually Valuable and I think it's just again. It's just just part of it being in the community If you know somebody or somebody has I don't know 100,000 Plus dollars to to blow on a picture and uh And you're in that inner circle to me It always kind of felt like Like the the country club in like the 40s and 50s where you get all these rich people together and then like hey I got this great deal or hey We're building this this new structure or whatever else and you can just talk to them because you're all rich And the rich just get richer So like it's the same type of thing with in these communities like oh you blew 100,000 bucks and I'm mutant ape Well, what else you know? Yeah, that's how I see it, but whatever Oh jerry Jerry says what do you think about the new luna plan and this was someone talked said about hey It's already up 40 and the numbers the numbers and I know that they're not going to use a an algorithmically backed Stable coin they're going to actually back that by I believe Crack me in the comments usdc and tether And that'll be the stable coin And there's gonna they're gonna try to compensate some of their People lost a lot of money I think that part's great But unfortunately as I've read different things do not sue me This is just the things that I read that a lot of some A good amount of ec's got bailed out first That's just what I've read and that could be totally incorrect because I don't know I am going to not touch that with a 10 foot pull And uh because the one trust is gone. It's gone, right? So I just wouldn't get into it because of trust right we've got a lot of There's so many options out there for you for crypto So why not just get into something that's uh Been around for quite some time has built a great community And has uh delivered to the best their abilities go from there All right, thank you So rob is now a good time to buy gold This is not the question specifically for me. I just buy it I because on my Roth IRA. I max out at seven. I think it's seven thousand six thousand or seven thousand dollars per year, right? So I buy like five percent of gold in my Roth IRA And then that's it. So i'm just done for the year anyhow. So uh for me as far as gold there's There's a guy rob at uh goldsilverprose.com. He's got a youtube channel. Check him out. He's really great on gold and of course Michael Maloney And uh, that's who I trust all the rest of the gold bugs. I don't Really know who they are. So but that's not my that's not my wheelhouse. I'm sorry Crypto lover Says hey rob. Nice to see you. How much conviction do you have in robber grin dome and hero projects? I will tell you this the the reason that I got into everdome was because of robert grim for dome and hero and I think I can I I think I can show you this If I can't just keep it between us. Let's see here Look up something No, it's not yet Hold on real quick. I'm gonna look up something from uh, show you an example of Everdome Is this it? now Wait, wait, wait No, that's not it One second hold with me staking snakes Jesus crimey christmas.  So what I like about Uh robber grins platform is For dome is the ability to actually Do these 3d lifelike scans and put them into the Uh cryptiverse or the metaverse and the reason the reason why I didn't realize just how expensive that is to actually do It takes like tens of like thousands of thousands of dollars to do that Right, but if you can scan something digitally and put it in and not have to have hire a ton of developers To do it it takes a bunch of time. So I think it's going to be a pretty good play in the future as far as uh with that Finally I found it. Jesus Look at this. So here's an example what I'm talking about This is a game For fame that they used with the ever dome tech or the dome technology And this is going to be a play to earn game. So when people talk about Graphics and they really want to see something a little bit better than than the blockiness of like say sandbox Here you go So I like to see this I loved it. I actually love to play this game. It's pretty cool So, yeah, I can see them doing some pretty big things. That's just my two cents. All right.  Everybody isn't everybody a fraud at some point seems like that's a fraud.  Yeah Suppose so I'll tell you right now. It's way better than uh, and the blockiness that's out there Although blockiness works okay for minecraft. So whatever And then yes, cornucopia's will be huge on cardinal. I have to agree with you there Uh, that's it. I think Okay, so that's it coming up on one hour So look everybody. Thanks for sticking with me on a sunday. Good times right like this video thumbs up subscribe all that great stuff And uh, that's it for today. So thanks so much for stopping by and I'll see you on the next one Christopher otl gets it in in the last minute. Do you think? damn it Do you think where you will face the same issues as block 5 and celcius? The differences between block 5 and celcius is voyeur doesn't this is my personal opinion They're not offering loans And I had steve on the show three weeks ago and one of the big things that I can see is I believe block 5 did loans I know celcius does loans to have a loan out with them So the question then is why did they get the cease and desist and voyeur didn't steve Look for that video. It was like three weeks ago. Steve said look we still have we still asked for collateral And we still rehypothecate and if they still rehypothecate And alex machinsky was on the show and he says the problem was rehypothecation And the question is what's the difference between you and them because they're still going Don't know anyhow, maybe the loans things that's it for today. So thanks so much everybody appreciate it And I'll see you on the next one. Adios


This lecture is entitled Adelaide La Biguillarde, Women Artists on the Rise. So last subunit, we discussed Elizabeth Louise Vigée Le Brun, who was one of the most important women artists in 18th century France. And this is a self-portrait of Vigée Le Brun from around 1782. And on the left here we have La Biguillarde, and this portrait is from around 1785. These women are working at roughly the same time in France, and they're both celebrated not only because they're successful women artists, which is still fairly unusual at the time, but they really wanted to promote the role of women artists in France. So all of these things that they have in common means that you often study them together. So we've already taken a look at Vigée Le Brun, and today we're going to be focusing on La Biguillarde. Now, she was, like her friend Vigée Le Brun, very successful, not just with any random patron, but she was successful with the very top levels of society. And that makes her really exceptional. And she was even accepted into the Royal Academy in 1783. And even more, she is famous for helping other women artists become successful. She actually took on women pupils and tried to help them become successful as artists. Now, she's famous for her portraits. And you can see when you take a look at this self-portrait, you can perhaps get a sense of why she was famous for her self-portraits. It's a very engaging, personal portrait. And just before we move on really quickly, I think you can see when you look at the self-portraits of Vigée Le Brun, the self-portraits of Vigée Le Brun and La Biguillarde here, they really present themselves as these beautiful, poised, self-assured women. And when we look at their full work that they did, their art really backs this up. They're very skilled, detail-oriented painters who really inject a unique liveliness into their paintings. So now let's take a quick look at a representative example of the kind of portraits La Biguillarde was famous for. So here on the left side of the screen we have one of La Biguillarde's portraits. And this is a portrait of a man by the name François-André Vincent. François-André Vincent. And this dates from around 1795. You can just kind of ignore the image on the right for just a second. So this is La Biguillarde's portrait of this man, François, who was one of her earliest teachers, painting teachers, and would later become her husband. So she has a lot of personal and emotional connections to the sitter here. And I think that comes across, it's really a captivating likeness of this person. And just as in this particular portrait, she's famous for setting her sitters against very simple backgrounds, often just a plain wall. And they're very frank, straightforward portrayals of these people. And here she shows François as an artist, right? He's holding a handful of brushes, he has a palette with paints on it. So right away we see not only this man and his character, but we know who he is, what he does, how he makes his living. So again, a very frank, kind of no-nonsense approach to this man's portrait. But it's still very lively and engaging. He has this kind of twisted three-quarter pose. The way he looks out at us is very engaging, making that eye contact. Even the way she's depicted his facial expression is very distinctive and individualized and very engaging. And now let's just draw our attention to the portrait on the right, which is from the 1630s, so quite a bit earlier. And this is a painting by Rembrandt of his wife Saskia. And I thought that would be an interesting comparison because we have two artists who are known for very engaging portraits and these are portraits of their spouses. But of course Rembrandt was working in the Dutch Baroque and there are very different tastes that informed art production at the time. And I think right away you can see Rembrandt is working in the trappings of the Baroque and right away you can see this use of chiaroscuro. She emerges from this very murky background and her face is brightly lit. Whereas in La Biguiarde's portrait, everything's much more evenly lit. There isn't that kind of sense of mystery created by the chiaroscuro. It's a much more frank and straightforward depiction of this person. So I think that is an interesting reminder of the direction that art is moving in this period. Away from the Baroque and towards something new which is very much in line with the interests of the Enlightenment. And finally I just want to move on and take a look at what is probably considered La Biguiarde's most famous painting. So here we have her self-portrait with two pupils. And you can see right here is the self-portrait we looked at a couple of slides ago. This is the image we were looking at. It's taken from this larger self-portrait. And it's her self-portrait with two pupils. Let me write that down. Portrait with two pupils. And it dates to 1785. And like I said, this is considered without a doubt her most famous painting. And it shows her as a painter, sort of like the last image we looked at with her husband. She's holding brushes and a palette and you can see the back of the canvas that she's working on. So she's engaged in her craft, actually involved in the act of painting. And she's also being shown as a teacher. Behind her we have two of her pupils and these are real women. We know who these women are and that they were in fact her students. So she's shown as a painter and as a teacher. And many view this as kind of a bit of propaganda, a bit of self-advertising for her worthiness for acceptance into the Royal Academy. And you can see how that might work. This is definitely very much about her role as an artist and her worthiness as an artist as she's engaged in her craft. Many have even pointed out in the background right here is a sculpture of a Vestal Virgin. And that's also sort of a pro-woman or feminist subtext there. The Vestal Virgins gave up traditional women's roles of being wives and mothers so that they could protect the city of Rome. So people have read a lot into that. But just like with the portrait we just looked at, I think you can see there's a real liveliness and interest in this painting, but also a tremendous amount of frankness, the way she looks right out at the viewer. She's not coy at all. She's very proud of her art and proud of her status as a woman artist. Before we finish up, I just wanted to point out the tremendous attention she pays to the details of the clothing, of her own clothing and her pupil's clothing. You can see this dress she's wearing, the tremendous attention to the color and the texture, the way the dress falls, the ruffles along the bust, the feathers in her hat. And even if you look at this woman behind her, you can see the sheer netting of this dress. And that's all, it's very sumptuous and beautiful, really draws us into the delicate details of this painting, but it also shows us how skilled she is as an artist that she can do this. So she's kind of doing a lot there by bringing our attention to these details. And really she's just provided us with a female-oriented view of the craft of painting. And by doing this, she's kind of helped establish the validity of women painters in France. And she really succeeded in doing this, and even today remains one of the most celebrated women artists of the era.


Yeah, let us get back to business, we are on the last leg, this is slog overs I keep saying, so that is what there is a saying, there is a difference between the hero and an ordinary person is that one who last long in the final phase is the one who is the real hero. So we have to even for winning 2020 or one day match, we have to play well in the slog overs. So that is what we will attempt to do now. So we are into heat exchangers, so I guess most of you or most of us are very familiar and this is the pet word which we routinely use heat exchangers, whether we really use them or not I do not know, but still I guess we all use this, okay. So as I said I will not derive anything on the plane paper, I am going to go reasonably fast because I am sure all of you have gone through LMTD NTU epsilon, but let us focus on more on interpretations, explanations rather than examples, okay. So that is why I am not going to spend time on what are the types of heat exchangers, what are the heat exchanger applications, all that I am not going to spend time at all. So let us get to heat exchangers but one clarification now that one of the persons had asked me, I thought I should emphasize, I usually used to go heat exchangers. Heat exchanger is a device, what is the device which we are worried about, here we are not in this heat exchangers or even in UG heat exchangers whatever we teach, we are not worried about direct mixing, one fluid is not directly going to mix with the other fluid, those are also called as heat exchangers, fortunately or unfortunately, but we are not going to be worried about those heat exchangers, here when we say heat exchanger, we mean here that they are going to be separated, there is no question of mixing with the hot fluid and the cold fluid, okay. So that is what we take up as the heat exchanger, now this is the hot fluid and this is the cold fluid, I have just taken tube in tube, so there are three resistances, you can easily see that, okay, there is convective resistance on the inner side, convective resistance on the outer side and then the conductive resistance, so now there are two approaches, one is the LMTD F approach or the LMTD approach, another one is the epsilon NTU approach. What is known in the LMTD approach? I know the inlet temperatures, outlet temperatures, mass flow rates, what is that I am supposed to do is this size my heat exchanger, so that is what I can do with LMTD approach, in epsilon NTU approach, I have been given the heat exchanger, it is there off the shelf in the market, I have been given the catalog of the heat exchanger, I know my mass flow rates and inlet temperatures, I need to predict what would be the outlet temperature, now my question is, can I do with epsilon NTU approach, can I size my heat exchanger using epsilon NTU approach? Sorry, reverse question I think, the question is, can I predict the outlet temperature using LMTD approach, how many knows, why not, because I am not going to go in a logical fashion, I am going to go in a high entropy way that is fine, why because epsilon LMTD approach means what? We will take up this question after we take analysis of LMTD approach, point is the answer is LMTD approach also can be utilized to predict the temperature, sorry to size the, for a given size to predict the temperature, for a given size to predict the temperature, LMTD approach can also be used, I have to just take the differential element, we will come to that little later, why I am saying this because we should be telling that to the student, it will be iterative, it cannot be in one, in one shot I will not get, I have to do it iterative, but we need to emphasize this to student, they should not be under the impression that it is exclusively epsilon NTU approach only can be used to predict the outlet temperature, we should not be giving that impression for that, because textbooks do not tell all this, it is for us to figure it out, okay, there are various types of heat exchangers, one is counter fluid exchanger, parallel fluid exchanger, double piped exchanger, I am just going to take tube in tube heat exchanger, because I am sure all of us have built tube in tube heat exchanger in our labs, we have enough field, why do we go for tube in tube heat exchanger, what is the typical wattage of tube which I can build it tube in tube heat exchanger or which is what is used typically for single phase if I am asking, I am not getting into two phase at this point of time, we are handling only single phase heat exchanger, typically I will not go about 6 to 10 kilo watts, it is not that this is a standard rule, why because the size of my tube in tube, how do I build my tube in tube heat exchanger in lab, it cannot be one pass, right, it cannot be one pass, one pass means only one tube cannot be there, if I get the length when I calculate the size of the heat exchanger, if the length turns out to be 20 meters, can I build a heat exchanger of 20 meters, how long will be 20 meters, 20 into 3, 60 feet, 60 by 10, 6 storey building, can I lay down 6 storey building, it is not possible, what would I do, I will have to take bends and make multiple passes, it is there here multiple passes, you have to take through multiple passes, you can go through lot of multiple passes, of course that will increase the pressure drop, everything comes with a cost that will increase the pressure drop, in spite of that taking multiple passes, there is a limitation up to which you can hold this tube in tube heat exchanger, then you will go for that is as I said in the handbook or it is not that I said 6 to 10 kilo watt, it is just a gross number, it is not that we cannot build tube in tube heat exchanger, if I have more space I will, I can always go for tube in tube heat exchanger, but I can make my size of the heat exchanger smaller if I go for other configurations, may be shell and tube heat exchanger, so that is why we usually do not go for larger capacities, tube in tube heat exchanger, this is the point we need to emphasize to the students. Now, parallel flow, counter flow all of us know, this is T H, what is this temperature, T H I, this is T H O, T C I, T C O, so here also same thing, T H I, T H I, T H I, T H O, T C I, T C O, so now this is about compact heat exchanger just to say that the area density, that is the heat transfer area, surface area upon heat exchanger volume, these are the typical values for various heat exchangers, for a car radiator this beta is around 1000, whenever this beta is above 700, it is called as, we use the word compact heat exchanger through the steam, so compact heat exchanger whenever the value is above 700, it is typically called as compact heat exchanger, I have just put human lungs because that will give you anything human is going to be highly efficient, highly efficient because nature knows how to optimize things by itself, so it has optimized and the human lungs heat exchanger is having a beta of 20,000, quite highly dense, so that is about the area density and of course there are cross flow heat exchangers, so they can be mixed, unmixed, one shell and two tube pass, two shell, four tube pass, all configuration, shell and tube means I think all of us know, in the present day in Google images, that is what I do when I go to the class, Google images I take the pictures and go and show them the shell and tube heat exchangers, of course not for UG, but perhaps we can do that for UG also, that is what I used to do for heat exchangers, these are plate fin heat exchangers, these are plate fin heat exchangers, that is there are plates in between there are fins, so that is essentially the heat transfer is taking place, the mode of the heat transfer is not only conduction, but also sorry, not only convection, but also conduction because through those fins, through those fins, so now locating those fins, roughening those fins, all that is an issue, it is not out of the world, in today's world I mean people are talking about single phase heat exchangers, single phase nuclear reactors, what is that high temperature gas reactor or nuclear reactor, I do not collect the exact name, but there is no HTGR high temperature gas reactor, gas cooled reactor, so cooling is going to be done not in two phase mode, it is going to be only single phase and there they are contemplating of using plate fin heat exchangers and in this the plate is not going to be straight, but the plate is going to be wavy, why, what is the nature of the flow which would be typically in a plate fin heat exchanger, imagine you consider this, there are two plates, you put so many partitions, the heat partition, the flow has to go through each partition, the flow is someone said laminar, flow is laminar, the only way to augment the heat transfer there is to, we have studied this, to increase the swirl, so I have to generate swirl, that is why this partitioning wall is made as a wavy channel, because it is going to be wavy, so I am going to create swirl or the velocity in the other direction not turbulence, it is going to be laminar only, flow is continuing to be laminar, but I am going to create swirl, that is I am going to make one laminar to talk with the another laminar by creating the velocity in the other direction, so wavy type plate fin exchangers, lot of researchers is going there, lot of research is going there, in fact myself and professor Tulsherma have a student, we have learned from through Bark only, we have a student who is a scientist in DRC who is doing the project on that, so that is there are plenty of applications of heat exchangers and it just came to me I just told, fine. So now coming back to overall heat transfer coefficient, I am not going to spend too much time on application that is it, so now let us see the resistance, because of course we have gone through, I am going to breeze through this, professor has already told this in conduction itself, so we have the convective resistance on the inner side, conductive resistance of the wall and the convective resistance on the outer side and I have as he had told whenever there is a u there has to be an area, so I have u i a i or u naught a naught, it is a good practice to keep this u a together, so you do not have to worry about what is that you are handling, so u is meaningless unless area is specified, we need to mention that because usually people ask what is the overall heat transfer coefficient, it is like asking mangesh choudhary which mangesh, I can have hundreds of mangeshs, but hundreds of choudharies, but which choudhary mangesh, that is what makes mangesh choudhary, so we need to qualify overall heat transfer coefficient whether it is based on inlet area or outlet area, so that is what is this and of course for if I have fins I am going to put the fin efficiency both on the inner side and the outer side, these are the typical heat transfer coefficient, I do not think I need to spend time on this, all that you will realize through this is that for two phase flow heat exchangers you will have higher heat transfer coefficient, of course here we need to spend time on fouling because fouling is the student cannot realize for us for all of us fouling is pretty common because we have been biased because we have heard it so many times, so we know it very well fouling we have to spend time fouling increases resistance to fouling is the sedimentation or because of some chemical reaction some scales are being formed, so the conductive resistance which I was neglecting which was only because of the thickness is going to get worse because of these scales, so how do I get this fouling resistance I have put here RFI and RFO how do I get this, how are those standard values generated, but how does one do an experiment to get that, no not by using used tube it is not possible to get the used tube, you do some accelerated chemical treatment experiments in our own labs, in fact fouling is such an important thing in a power plant I always quote this example I learned this hard way when we had a BHEL we were myself professor around RPV professor Vedula and Kananayar we were involved earlier although we got declutched later on we were having discussions with BHEL Trichy, so when we were designing that supercritical boiler design when we were talks were there a person from a chemical engineer had come for those discussions his job he said that his team's job is to control the pH of the fluids throughout the plant why because if it does not control the pH or maintain acidity or basicity properly it is going to affect my scaling, so that is the importance in real life is scaling, so scaling is taken care in real life in any power plant, any power plant it can be coal base, nuclear base, any power plant scaling is going to be a nightmare if I do not take care of the efficiencies properly I remember one of the steam power plants in one of the handbooks I had read the after 5 years in Russia after 5 years when they did the energy budgeting the pumping power went up by 20 to 25 percent after 5 years why because scaling is negative effect because I have to if I have to keep the same flow rate which otherwise would have had lesser pressure drop because of scaling my pressure drops have gone up how many times I can open a meat exchanger and clean it it is not possible and many a times I cannot reach everywhere if it is a shell and tube it exchanger most of the times I cannot reach every nook and corner and do the descaling it is not possible even though I have done it may not be so efficient here we need to stop for students and emphasis that is why I have written chemical treatment plant pH and if scaling becomes a problem periodic cleaning it is not leaning periodic cleaning has to be done and downtime penalties are there so they do not like to shut down the plant so that is that is what we need to emphasis with the students and coming back to measurement they do scale that is fast rated experiments they they have their own mechanisms of whatever scaling would have occurred in 10 years I will do it in shortest possible time by chemically increasing the concentrations are doing something these are what are called as accelerated experiments okay of course I can get the tube but not always I can afford to get that information so that is how this RFI and RFO whatever we get in the standard table are okay so these are the typical RFIs only I keep spending and tell them that you see this is meter squared Kelvin per meter this per watt this implies that if thermal conductivity is 2.9 it is 0.3 mm thick if it is made of 9 I mean this number will not give me the feel this number only will give me the feel you see if this much is the fouling it can generate it is equivalent to 0.3 mm thickness of 9 stone 9 stone thermal conductivity is quite small 2.9 okay fine so there is a problem I am not going to spend time this is the problem I we just put this because we just want to show yeah through this problem what we try to show is that HI AI HA H0 A0 and initially I take a K here I have taken stainless steel where in which I have taken K of 15 this value has come with 15 although I have not shown this if I change this with copper my K will go up to 400 and the conductive resistance will become one order less here it is 9 into 10 to the power of minus 3 here it is going to be 0.01 into 10 to the power of minus 3 that is the reason why I tell that in refrigeration all condensers evaporators every one are made of copper tubes that is what I emphasize on there okay material selection is a biggest issue in heat exchanger design so why copper tube is so rigorously used is because of this this number calculation will tell me otherwise the resistance is thrown now this resistance is pretty small compared to these 2 okay another thing I think I am going to digress little bit here there is so much we can do here with this this little calculation I can calculate I want to spend time 1 more minute or 5 more minutes on this because we have time I can do measurement of heat transfer coefficient with this equation let us say I make conductive resistance 0 that is it is very less I take a thinness cosplay now I want to measure inner side heat transfer coefficient can I do in this heat exchanger tube and tube only let it be parallel counter it does not matter I have 3 resistances HI based HO based and K based conductive conductive resistance I have made it as thin as possible so it is gone so it is now between HI and HO how can I make this I want to measure the heat transfer coefficient on the inner side okay that is one option basically what he is saying is H0 I am going to increase it incessantly high steam it is little difficult to get steam I would say if I am to measure the heat transfer coefficient on the inner side with air as the flow medium let us say I can use outside what is the other fluid you can easily think of which you can get it in the lab water keep your mass flow rates very high so then the Reynolds numbers are high HOs will be over the order of thousands and HI is of the order of 20s and 30s at the most 100 so then what will happen my UI AI is going to be equal to how do I get Q dot now I guess you are with me now I can get my HI because Q dot I know so this is another way of measuring heat transfer coefficient which you can perhaps try in your own heat exchanger I do not know because both sides usually we use water water but we can build one with water and air and people use this why I am quoting this example because if you want to go back home and do a research you want to try twisted tape or you want to come up with your own configuration new configuration put it on the inner side put the air make the air flow through it and in the outer annulus you make the water flow or if you are handling laminar heat transfer coefficient perhaps you can do this make the water on the inner side make it laminar on the outer side even though it is water in all the heat exchangers which you have to go back home and try this experiment inner side you keep the flow rates very less such that the flow rate is laminar outer side you keep the flow rate so high as much as your pump allows you do not think twice check the mass flow rates check H O A naught make sure that it is very small even if it is not small if you can quantify can you quantify outer heat transfer coefficient if you know the mass flow rates yes or no yes because I know the Dittus-Bolter correlation I can apply Dittus-Bolter correlation I know that it is turbulent make sure that it is turbulent and apply Dittus-Bolter correlation you get H O now you should be getting in the same heat exchanger check it out then now the question is now you will get into trouble what is the Nusselt number you will get some representative Nusselt number it will be neither 3.66 nor 4.36 why because couple of issues it is going through developing region to fully developed because I am going to get one average number one average number I am going to get you will get somewhere between 3. sorry somewhere little higher than 3.66 it is going to be in heat exchanger typical boundary condition nearest boundary condition what is that you would think of constant heat watch or constant wall temperature nearer to constant wall temperature nearer to constant wall temperature not truly constant but it would not Nusselt numbers you cannot expect around 4.36 they have to be 3.66 but because you are traversing through developing region the Nusselt numbers may go up but please go back and try okay why I am saying this because this little equation again yeah why why why imagine let us imagine how can it be constant heat flux how can it be constant heat flux yes even in constant wall temperature case same thing it is we were worried about the heat transfer from fluid to plate does not mean that see what is happening from here to here if I take on the outer wall if I said cold wall side I am going to keep the flow rate very high if very high mass flow rate is there means what would be the temperature difference between m dot c in and m dot c out so that my line of thought is not over you have to be with me to come to cover you so if the mass flow rate is very high and the temperature gradient is very less the temperature difference is what on the outer side very small so it is that is the reason why we are saying in fact when we do the experiment we should take care that my mass flow rates are so high that my temperature differences are negligibly small but that depends on my pump capacity if it is going to be 0.2 hp only if you can replace replacing a pump I do not think in the present day is not a big headache change it to 0.5 hp you will get higher mass flow rate okay so what I am trying to why I am coming up with ideas is I am working around your constraints whatever setups you have what all experiments you can do with your own setups that is what I am trying to do okay fine so then coming back okay now let us come back to traditional LMTDF approach and epsilon NTU approach so first let us take up LMTD approach and typical here before analyzing we make all assumptions this is where we have to spend time steady flow will it will any heat exchanger work under steady flow typically typically in a power plant let us say how many days or how many hours or how many minutes a typical power plant will take to reach steady state couple of hours couple of hours it is going to be so point is and loads are also going to vary it is not going to work work only under one load so my heat exchanger normally is not going to work and is it will take enormous time to reach steady state why do I say this why do I say that heat exchanger is going to take enormous time to reach steady state why do I say this I you have to tell me from transient conduction fundamental principles thermal inertia rho v c p of my heat exchanger heat exchangers are as big as this room or building for a power plant so rho v c p of this building how much it would be building means building size heat exchanger that much fluid it is going to be very very large so this assumption of steady flow is in real life is not right this we need to impress however for the sake of simplicity we are taking it as steady flow another kinetic energy and potential energy changes are neglected is it true is it true in power plant one tube is sitting in third story building another tube is sitting in first story at the ground floor there is a potential head but I am neglecting that and it is going through all sorts of bends it is going through contractions expansion because it has to go through all sorts of connections so there is going to be velocity change there is going to be kinetic energy associated with it in any derivation for that matter assumptions is the place where we need to spend more time than the derivation itself okay all the more important in case of heat exchangers next thermo physical properties constant over the length is it true perhaps it is true if I am handling air but in water or liquids properties are going to be going here so but nevertheless I am going to go ahead and make life simple and say that thermo physical properties are constant but once you do this after doing this you can ask them to change the analysis for varying properties if I take the varying properties what will happen what is that will change my hi and ho I have to consider the variable properties if you closely look when you go back home in the notes for variable properties in the correlations there is a term called mu b by mu wall to the power of 23 in all the correlations that essentially takes care of the variation of the properties so point is thermo physical properties are constant is assumption perhaps in a plate finite exchanger which is taking air as the fluid if it is air as the fluid it is not an out of the world assumption okay no heat loss to the surroundings you have done the experiment so much discussion on q cold plus q hot by 2 we took okay so that is not right because point is there is going to be heat loss there is bound to be heat loss it has to talk to atmosphere I am not outside the world I am inside this world and heat transfer coefficient is constant over the length is this right perhaps not a bad assumption in heat exchangers I would say it is not a such a serious assumption why because heat exchangers are quite lengthy quite lengthy initial heat transfer coefficients are going to be high is this assumption going to be affecting on my heat load will it increase my heat load or decrease my heat load if I designed a heat exchanger let us say my heat exchanger is short where in which half of the length is fully partially developed sorry developing and half is fully developed but I will go ahead and make the design of the heat exchanger and design it for a given heat capacity or I will fix my heat exchanger size and design it and get one load but actually in real that is the design load but real life load will be more or less than this will be more you are telling the same thing but you said what heat transfer coefficients I have taken lower no than the actual so that means I have taken a conservative estimate of the h so my load has to go up that is what you meant in the mind but most of the times that is what my teacher used to say most of the times you will tell opposite than what you thought that is why he used to tell me whenever your teacher asks you a question stop a while stop a while do not answer immediately even if a student ask you a question you should not respond to him the way I respond very fast you should not I am very impulsive it should not be like that you take a while ask him the same question to rephrase again you also rephrase it so that everyone else understand then you respond by that time you would have mentated that do not answer it impulsively mostly when we answer impulsively we are wrong we are exactly telling opposite of what we intended to tell one assumption pressure drop along the length of the heat exchanger what should it be how how will it affect the design here in this design I am not bothered about pumping power I do not care which size pump I am putting I just all that I say that these are the mass flow rate how I get it I do not care it later on eventually I will have to worry about that in this analysis at this point of time what is trying to say is that we are not worried about the pumping so now I think we do the energy balances MCC MCC PC I do the energy balance and I call this as CCC H and I think I can skip this this is the general thing which we draw okay I have taken this from chengal I do the energy balance I do not intend to do this derivation I do not intend to do this derivation because you all would have done n number of times so you do the energy balance basically and all that I need to tell is why is this plus and why is this minus that is all that is all one is gaining one is losing so that is why these things only we have to emphasize more with our students okay so that then they will get trained even when they start studying a textbook on their own what to look for and what not to look for okay so this is DTC DH and then we have an alternate method I equate that I get the temperature difference and I tell that is delta T LMTD this also we have defined already in convective heat transfer this is the parallel flow heat exchanger so we get for parallel flow this one and counter flow this one so similar I usually give counter flow heat exchanger as a exercise I solve it for parallel flow and give it for counter flow and we all know that counter flow LMTD is greater than that of parallel flow LMTD counter flow heat exchanger derivation how many of you have done this please go others please go ahead and try it okay it will not come as simple as this that is why I have put the derivation here in case if you get stuck I have not skipped it I have not skipped it I have given the derivation okay and please go ahead and try and in fact we upload this notes completely the way we are uploading for model in fact the same notes what we are teaching you is the one which we are using for our UG class yeah it is there what I am trying to say is you can share all this with your students my one of my close friend who is in faculty in IIT Madras used to tell this is a fight of knowledge the tools have to be common in war one of the rule is what both the both the guys should have the same weapon so why I keep telling why I take this example because what I am reading to understand something has to be told to my student he can also go back and read maybe we will understand more than what I have understood and he will come back and question me in that discussion I will also learn something that is the reason there is there is there should be that is why we are all worried about open source we should be sharing all the information that is one thing knowledge is one thing which will multiply by sharing okay so our motto in our IIT is Gnanam Paramam Deayam so we need to share only when we share we will learn more why I am taking so many examples because whatever most of the times when I was studying my teacher will not tell where is he taking it from I have to break my head after that course is over somewhere I will realize are you are yes either have had I read that of immediately after he had taught me it would have been so much easier for me to understand that is the reason why I am emphasizing so much don't be secretive about your information what you are assimilating to teach just give him he will make you understand much more than what you have understood believe me our students are much smarter than us I think you all will agree with us no no two ways about it they are all smarter than us they are all smarter than us with that assumption if I start if with that assumption if I start my life is that much easier for that much easier okay anyway I got diagnosed fine so there are lots of problems you can solve that okay this is a standard I think we all give this what will happen I think we will not harp on this you can apply a law special rule and show that this so I think all of us this is a stock question why I don't want to spend time on this and condenser and boiler also professor has told why is LMTD counter flow less than why is LMTD of counter flow higher than the LMTD of parallel for that I just want to put the temperature profile so that that may aid in the thought process aid the thought yes here more or less the temperature gradient is reasonably that's that's that that reasoning that was a very valid point that's what we need to emphasis I will go to I think now it's time to shift to our gears to epsilon NTU and of course there are only one point I would tell before going to epsilon NTU I saw in your data handbook also code and Ram data handbook also what I will do is that textbook I will purchase that code and Ram's handbook so that I can modulate accordingly the notes let us see because most of the things are there in that it's nice actually it's really nice so here we give some correction factors if it is if it is a multi pass and cross flow heat exchanger there are some charts you know these charts do you teach these charts yes so what are these F what is this F actually what is the physical significance of F what is its value going to vary between always in all of these charts it's anywhere between 0 to 1 what does that physically mean I will just tell physical meaning and tell where is this coming from how are these charts generated for that matter experimentally obtained no they are not experimentally obtained analytical solutions ok in fact in heat exchangers course we teach them how to derive that ok do not give the impression that they are experimentally obtained any experimental data cannot be looking so nice all of us agree with that we had enough problems with little little experiment ok so these are all analytically derived when I say analytically derived there are again inbuilt assumptions these results are valid to the extent of the applicability of those assumptions so this is not Bible or Bhagavad Gita or Quran ok this is again valid to the assumptions ok to the extent of the assumptions ok so that that point we need to emphasize and another point I thought ha F is between 0 to 1 what does that mean I am applying it to what you see UAF delta T LMTD for what is the reference I am taking counter flow why that is the best possible heat exchanger any other heat exchanger I build it is going to be not better than counter flow heat exchanger that is why my F is going to be between 0 to 1 this two points we need to emphasize before we blindly apply this chart charts all of us can apply know this do not know that you get that you put this you are going to get the heat transfer coefficients why why you made one statement why are any other heat exchangers poorer in performance than the corresponding counter flow heat exchanger why should it be why counter flow is the best that is that is the ideal thing that is the question no no no what did we say why did we explain parallel and counter flow counter flow is better than parallel on what grounds we told the temperature gradient as my fluid is traversing throughout the heat exchanger the delta T's have to be reasonably constant that cannot be achieved in any other configuration you go back and think in shell and tube heat exchanger cross flow heat exchanger plate fin heat exchanger you cannot achieve that is the reason it is delta T LMTD counter flow is taken as the reference ok these two points we need to emphasize when we tell our students doing calculations they will do it because once we do once we tell them how to apply this relation they will do it so I am not going to tell you how to apply this chart P is known R is known I am not going to tell you all of that ok so with that I guess this is for cross flow there are n number of problems at the end these are all taken from chungal actually I will stop and I have just put the procedure I have just taken the recap I am not going to do that again ok so you can take a recap before going and another thing I want to tell before starting the second you have started today first class you have taken when you go to the next class what do you do with the first thing last class we need to discuss and there our power point helps you cannot again summary is using the board so if you can offer to have power point you flash the power point spend 5 to 10 minutes first because we are sure no student would have read and come that can be taken for sure ok even if someone has read it is good that he will understand it much better and maybe some doubt will crop up in his mind and he will ask he will definitely ask and encourage questions I have been always asking what are the questions what are the questions to the best of my our possibility we have tried to ask answer the questions not that we can answer all the questions but we need to inculcate the habit of asking questions so that we are thinking ok ok let us say excel and to be the exchange how does it consist of there are multiple tubes ok and through the shell it is coming and getting out through the shell and there are baffles ok and it is not going to go through H0 I cannot compute ok I have to go through serpentine passages so there is lot of empiricity in that and definitely because it is not the heat exchange is not as proper as it would have occurred in counter flow it is sorry tube in tube counter flow heat exchange oh no we cannot call any of other heat exchangers as parallel and counter. How many of you are with me when I say shell and tube exchange all of you can imagine shell and tube so there is in cross flow heat in shell and tube heat exchanger is there any counter flow all the time no sometimes my fluid is going up that is why it is somewhere between very rightly told parallel cross counter so but I have taken one case parallel one case counter so any other case has to be in between these two that is how I think ok.


Abandonment is a strong word. No one wants to be abandoned, but a pervasive fear of abandonment is something that can be picked up on and addressed by a licensed therapist. Here are a few ways you can spot a fear of abandonment in yourself. How does a fear of abandonment form? Examining the childhood of people with a fear of abandonment, one thing stands out. Loss. This loss could come in many forms. The loss of a close friend, a close family member, or divorce can all lead to a fear of abandonment. A study on the effect of divorce was published in the Journal of Abnormal Child Psychology and another separate study on the effect of the loss of a parent was published in the Journal of Youth and Adolescence. A common finding between both of these studies was the effect each event had on attachment and that both events were in origin for depressive symptoms. Other factors can contribute as well, such as constant ridiculing or lack of physical affection. Children require a lot of love and care, but sometimes parents don't consider the long-term effects of how they speak and act around their children. But a child can't look at you and say, hey, I have a fear of abandonment. So how else do we know a fear of abandonment is forming? Look at your attachment style. These can change over time, but can be present from your childhood into adulthood. This is a good indicator of a fear of abandonment, no matter what stage of life you're currently in. Abandonment issues and a fear of abandonment are a form of anxiety. People with a fear of abandonment typically show signs of an anxious or an avoidant attachment style. According to psychologist Dr. Francis Stevens, people with different attachment styles cope with emotions in different ways. People with an anxious attachment style have trouble controlling their response to emotions. People with an avoidant attachment style have trouble recognizing emotion. If you have an anxious attachment style, you might hate being alone. You might have a poor sense of self-worth and you might constantly be aware of potential threats to your relationships. It may feel inevitable that your partner or close friends will leave you. In your relationships, you might constantly require validation or reassurance. Seeking reassurance is a normal thing from time to time, but a constant need for reassurance points towards a deeper insecurity that could potentially come from a fear of abandonment. Physical touch. If you feel like something is wrong in your relationship just because your partner hasn't reached for your hand, hugged you or kissed you in the last five minutes, you might have an anxious attachment style. Remember what we said earlier? A lack of physical affection can contribute to a fear of abandonment forming in your childhood. See how the way our childhood unfolds affects our lives. A study on affection deprivation by psychologist Corey Floyd found that being deprived of affection negatively affects us in many ways, namely general health, happiness, social support and most importantly with regards to a fear of abandonment, relationship satisfaction and attachment security. We will always try to fill the voids we find in ourselves. We want words of reassurance and physical affection because it's a vital part of our upbringing that we never had, so we look for these things and the people we're closest with now. So, have you asked yourself if something has happened in your childhood that might have caused you to be afraid of abandonment? Is something happening now that makes you think that this fear is influencing your closest relationships? How will a fear of abandonment affect your future? A fear of abandonment doesn't have to define your relationships with friends and family for the rest of your life. All it means is that some people might think of you as clingy or needy and it can make relationships frustrating for you as well. It may feel like there's always something missing. You aren't getting enough affection or attention. Your friends don't care about you.  These thoughts build resentment. A fear of abandonment can cause you to grow distant and avoid building close relationships. According to communication experts Craig Fowler and Megan Dillo, people with attachment styles that indicate a fear of abandonment often cause conflicts that result in their fears becoming a reality. It can be lonely. But, there is hope. A fear of abandonment is something that can be identified by a licensed therapist. They can offer you tools that will aid your journey through your fears and lead you to a place where your relationships can feel more complete. Aside from professional help, your partner should be someone who is understanding and present. Get to talk to them about your fears and the things they can do to feel present. And if you are the partner or friend of someone who has a fear of abandonment, you could use your words in reassuring your partner. According to a 2009 study published in the Journal of Social and Personal Relationships, couples with insecure attachment styles tend to have worse communication. So if you or your partner has a fear of abandonment, communication should be a major focus, with the goal of making one another feel secure. You're only human. You can get distracted or busy and can't give your partner attention 24-7. So whenever you have a chance, just tell them you love them or send them a text saying you're thinking about them. It can't hurt to do this regardless of whether or not they have a fear of abandonment. Just bear in mind that a person with a fear of abandonment may just require a little more attention. Try to become familiar with the anxious and avoidant attachment styles to better understand what they might be thinking and feeling in order to avoid conflict. So do you or a loved one struggle with a fear of abandonment? Share some tips that have helped you in the comments below. Remember to leave a comment if you found this video helpful or interesting and subscribe to Psych2Go for more content like this. Thanks for watching.