We are discussing hydrogen atom. We have talked about a couple of quantum numbers. And now we are going to discuss the quantum number that we are perhaps most familiar with and that is principal quantum number. Remember all the discussion of not just hydrogen atom but also quantum mechanics. One of the beginnings of quantum mechanics is this transitions from one level to the other of hydrogen atom which showed up as line spectra of hydrogen atom and from there different experiments revealed different features of the spectrum and that is what led to the idea of quantum mechanics anyway. So, today we talk about principal quantum number. But before that let us do a quick recap as usual. What we have done so far in hydrogen atom is that we have been able to write Schrodinger equation and separate perform separation of variables and hence generate three different equations. One in R, one in theta, one in phi. And we have solved the phi part and we said that it is exactly the same as our treatment of rigid rotor and from the phi part we got this wave function 1 by root over 2 pi e to the power plus minus i m phi. And we showed that when Z L Z operator operates on phi it gives an eigenvalue of m h cross. So, phi is what phi contains information about the Z component of angular momentum. And from here by using cyclic boundary condition we get the magnetic quantum number. Magnetic quantum number takes values of 0 plus minus 1 plus minus 2 plus minus 3 and so on and so forth. And what we have not solved explicitly but given you the results is the solution of the theta part which yields another quantum number L. The solution of theta part capital theta turns out to be an associated legendary polynomial in cos theta. And what we see is that this beta turns out to be L into L plus 1. And when L square operator operates on the angular part of the wave function we get h cross square multiplied by L multiplied by L plus 1 multiplied by the same wave function. So, it is an eigenvalue equation. This is the value of square of angular momentum. And hence we had worked out that the value of total angular momentum of electron in hydrogen atom is square root of L into L plus 1 multiplied by h cross. Now, let us start talking about the R part. Once again this is a differential equation solution to which was already known by the time people started working on shorting an equation of hydrogen atom. So, there was no need for them to really work it out all of I mean from the beginning. So, I mean in the present day with this COVID-19 outbreak one term that has become very familiar with many of us is repurposing of drugs inventing a new drug is not so easy it takes many many years. So, what people are trying to do is that they are trying to use already existing drugs and explore whether they have any efficacy against this novel coronavirus. So, similarly already existing equations were sort of if I may use the same term repurposed to get the solution. So, with little bit of digression but I mean let us not forget the times we live in live in. So, this equation solution of this was already known and the solution was when put in context of this hydrogen atom problem solution turned out to be R it was a function of two quantum numbers n and L we know about already n is the new quantum number that we are going to talk about that is a constant the constant is factorial n minus L minus 1 divided by 2n into n plus L factorial to the power 3 the whole thing under square root sign that multiplied by 2z divided by na what is a a is 4 pi epsilon 0 h cross square by mu h square if you remember or if you just go back and have a look at what we had said while discussing both theory in very brief this is the expression that we had got for the radius of the atom. So, this is essentially Bohr radius and very soon it will boil down to Bohr radius of hydrogen atom. Now this is a constant we do not really have to remember all this all we need to know is that this is a constant then the next part is important you have R to the power L L. So, R is the radius that will be raised to the power L. So, for if L equal to 0 that will just be 1 L equal to 1 it will be R L equal to 2 it will be R square and so on and so forth. So, something that increases as a function of R that is multiplied by e to the power minus Z R by na 0. So, that is an exponential decay in terms of R. So, you have unless L equal to 0 you have an increasing function of R multiplied by a decreasing function of R but that is not all you also have that multiplied by a once again another kind of polynomial the solutions are all so sort of power series solutions we always end up getting this polynomials and this polynomial that we get here these are called associated Laguier functions. So, associated Laguier functions you do not really need to know their form but just remember that this associated Laguier functions are functions of R multiplied by some constant that constant is 2 Z divided by na 0 but we do not need to remember all that all we need to know is some constant multiplied by R to the power L this I would like you to remember constant multiplied by R to the power L e to the power minus constant into R multiplied by Laguier function in constant into R that is what that is the general form of the R part of the wave function. Now let us have a look at this function by function but before that let us also state something that we have said already that n takes up values of 1, 2, 3, 4 so on and so forth it can go up to infinity it also puts a restriction on the value of L remember beta is the bridge between the R dependent part and the theta dependent part and theta dependent part gives rise to the values of L anyway. So restriction on L and the restriction essentially is L has to be less than n that comes from applying the boundary conditions here one more thing energy when you do the full quantum mechanical treatment turns out to be exactly the same as what was predicted by Bohr theory does that mean that Bohr theory was correct and all this discussion that we are doing is rubbish not really Bohr theory is not correct it is just that it gives the right answer it gives the right answer because the physical assumptions and considerations in many cases are actually valid but we still cannot really use it because it is a 100% classical theory it violates uncertainty principle and also it uses classical and quantum maybe it is not right to say it is 100% classical theory it uses classical and quantum theories reversibly whenever whichever is more convenient that is not such a good thing to do most importantly it violates uncertainty principles we cannot use it this quantum mechanical treatment is the way to go but the beauty is even though Bohr theory is not really correct it gives the correct values of many physical quantities energy being the most prominent of them you might remember that one in one of our earlier modules we had said that the value of Rydberg constant that we can predict from Bohr theory turns out to be fairly accurate when compared with the Rydberg constant determined experimentally why is that so because Rydberg constant essentially comes from difference in energies of energy levels so that 1 by n square is there everywhere so interestingly we get the same value of energy as that of Bohr theory but maybe it is not such a big surprise because you knew that Bohr theory does give the right value of energy anyway but let us not put too much of weightage to that let us move ahead one more thing that we should say is that interestingly in this expression for E the only quantum number that makes a contribution is n and not L remember what we are doing here we are working out Schrodinger equation for a hydrogenic atom hydrogenic atom means a one electron atom so for a one electron atom what we are saying is that L does not contribute to energy however when we have more than one electrons in an atom L is going to have a rule to play so we will talk about it when the time comes for now let us have no confusion about this that different L values for the same n value are associated with exactly the same energy minus 13.6 by n square electron volt for hydrogen atom and hydrogenic atoms L comes in only when you have more than one electron and your phenomena like screening shielding so on and so forth so the only thing that is there is the radial the radial part is the only part that makes contribution to total energy. So now we have reached a stage where we have talked about four of the three quantum numbers that we know n L and m and we have come to a reconciliation with what we had said using old quantum theory that n specifies the total energy of the electron in the atom L talks about orbital angular momentum m talks about z component of the orbital angular momentum what we have not obtained and what we will not obtain at all from the Schrodinger treatment is the spin angular momentum quantum number spin is something that arises out of relativistic quantum mechanics direct treatment. So that is something that has to be brought in externally if you remember and we are going to say this again later on if you have a free electron then it is not associated with any n or L or m n L m these quantum numbers arise due because the electron is in the field of a nucleus however even for a free electron you do have s you do have what is called m s m s has values of plus half and minus half once again they denote the contribution of the spin angular momentum towards the z axis. So z component of spin angular momentum we will talk about that in more detail when we discuss multi electron atoms for now let us move on to the next section with the understanding that we develop a concepts of n L and m interestingly in the opposite sequence remember in both theory n came first then some of it modification brought in L and Zeeman effect necessitated bringing in m in Schrodinger treatment however m comes first followed by L followed by n because that is a sequence of a solution of Schrodinger equation s comes from some place else right but with that understanding let us now continue with our discussion of the R dependent part capital R. So let us have a look at the functions as we had said few minutes ago this here is a general form what we will do is we will write rho for 2 z r by n a because that is something that keeps arising everywhere we will write a for this 4 pi epsilon 0 h cross square by mu square and since it is hydrogen atom when mu equal to m e we are going to write a equal to a 0. Now this is the wave function radial part that we get for n equal to 1 l equal to 0 and just for the record it is the only part remember when l equal to 0 then this l part and phi part are just constant. So that gets a subsumed in the normalization constant and this is what we get. So it is a simple exponential decay in R remember l equal to 0 so r to the power l equal to 0 and this Laguerre function that also is a constant. So it is for n equal to 1 l equal to 0 that is a simple exponential decay in R. Now even though we have not written it in the slides we are going to I think talk about it in the next module let me just say something here n equal to 1 l equal to 0 denotes an orbital I think we know that it denotes a 1 s orbital. So even though I might be jumping the gun a little bit let me pop this question right now what is an orbital and let me give you the answer. An orbital is an acceptable solution for Schrodinger equation for a 1 electron atom some of us might be taken by surprise by this definition because in many textbooks especially in 11-12 level it is written in bold letters that an orbital is a region of space in which the probability of finding the electron is maximum well that is a very popular long definition that region of space where probability of finding the electron is maximum can be worked out using the orbitals but they are not orbitals. An orbital by definition I will repeat is an acceptable solution of Schrodinger equation for a hydrogenic atom which is a 1 electron atom and these are solutions we can get directly like what we are getting right now we are talking about only the R dependent part we will come back to this orbital business in the next module. Let us go ahead n equal to 2 l equal to 0 we get once again a constant multiplied by e to the power minus r by 2 0 no harm done multiplied by now you see 2 minus r by a 0. So this R to the power l what would R to the power l be l is still equal to 0.  Now that brings us to a an interesting something maybe I just draw it even though we have talked about it a little later. Let us say I want to plot this function what will it look like I can call it I will call it capital R because it is only function of R capital R for 1 0 if I plot it as a function of R it is just some constant multiplied by e to the power minus r by a 0. So this is what it will look like and we have a better looking diagram in the next slide what will this look like here you have the same e to the power minus r this time by 2 a 0 so it will be a faster decay but multiplied by 2 minus r by a 0. So this 2 minus r by a 0 can become 0 somewhere this whole thing where does it become equal to 0 where R is equal to 2 a 0. So this factor becomes 0 at R equal to 2 a 0 and then it does not matter what the value of e to the power minus r by 2 a 0 is the product will be a 0. So if I try to plot R 2 0 against okay I forgot to write the x axis here this is of course R please believe me that I have written R what will happen at R equal to 2 a 0 this will become 0 so it will go down become 0 and we are going to show this many many times so please forgive my poor artistic skills for now. So the point is there is a node in the function remember nodes what is a node a node is where a wave function changes sign through a value of 0. So here the wave function changes sign so this is plus this is minus okay of course plus and minus are related. So that is where a node is and what is the locus of that node R equal to 2 a 0 R equal to 2 a 0 is the equation of a sphere is not it. So in 3 dimensions this sphere is the node for the 2 s orbital okay. So along this spherical surface the 2 s orbital changes sign goes from plus to minus okay. So remember 1 s orbital has no node 2 s orbital does have a node and since the node arises from equating the radial part to 0 this is called a radial node okay more about that in a while for now let me show you n equal to 2 l equal to 1 here there is a theta phi part okay in fact phi parts will be for m equal to 1 0 minus 1 okay but if you look at only the radial part then what we have is once again some constant multiplied by R by 2 a 0 multiplied by e to the power minus R by 2 a 0.  So what you get here is essentially a function that goes through a maximum. So if you plot capital R for 2 1 n equal to 2 and l equal to 1 so that is a 2 p orbital remember against R what do you get it never at R equal to 0 what do you get at R equal to 0 obviously it is 0 e to the power minus R by 2 a 0 is 1 but R equal to 0 so at R it is 0 at sorry at R equal to 0 the function is 0 at R equal to infinity also it is 0 so it goes through a maximum. What is the value of R where the maximum arises well you just differentiate this and equate to 0 you will find what is the value of R where this I think sorry where this function goes through a maximum it is very simple differentiation. Let us move on n equal to 3 l equal to 0 now see we have here things are getting little more interesting again R to the power l right R to the power l l equal to 0 so R to the power 0 is equal to 1 here R to the power 1. So here we have 1 minus 2 by 3 R by a 0 minus 2 by 27 R by a 0 to the power 2 so a second order polynomial multiplied by e to the power minus R by 3 a 0 what will this function look like if I plot against R what is this function going to look like I am plotting R 3 0 against small R now see this is a second order polynomial if you equate that to 0 you will get a quadratic equation and that quadratic equation is going to have 2 roots and just believe me when I say the roots are going to be real. So in 2 places for 2 values of R the wave function will become 0 so to start with if it is plus then it should come down become 0 here become negative but again it has to become 0 here so it will increase like this becomes 0 here becomes positive then of course it has to go down somewhere and become equal to 0 asymptotically what is this point what is this point what is this point these 2 can be obtained but from the quadratic equation and this point and this point you can find out by differentiating the function the whole function and equating to 0 not very difficult thing to do hence we can go ahead and we can write down different functions so by looking at it and I leave you to figure this out we get something well this is absolutely empirical just by looking at the functions we see that the number of radial nodes turns out to be n minus l minus 1 so when n goes up number of radial nodes actually goes up but then when l goes up it goes down because it is minus l that is why you have this alternate not alternate you have this functions going through a node and then not going through a node also as you increase n so this is the number of radial nodes and this expression is again something that we know from our high school days right so this then is a brief discussion of the radial functions of hydrogen atom here now this slide has become not very important I am going to show some prettier pictures of this when we talk about contour representations of orbitals just remember 1s and 2s orbitals are functions of r only and now we come to this interesting question that take the s orbitals look at say 1s orbital or 2s orbital 2pz has a value of well psi of 2pz has a value of 0 when r equal to 0 but what about 1s what about 2s what about 3s for all of them the maximum value of psi is at r equal to 0 so the maximum value of psi square these are real functions of course maximum value of psi square is also equal to r equal to 0 what is the meaning of r equal to 0 r equal to 0 is the position of the nucleus so are we saying that the maximum probability for finding an s electron is at the nucleus because if we do then we are back to square 1 square 0 because once again if the maximum probability of finding the s electron is at the nucleus then it is very similar to rather fort situation where the electron and nucleus would be at the same position so plus and minus charges would annihilate right the atom sort of gets short circuited that cannot be the case so the fallacy here actually we do not it is very important to remember that psi psi star is not probability psi psi star gives us probability density so it is true that s orbitals have maximum probability density in the nucleus at the nucleus that does not mean that probability is also maximum because you might remember well you do remember that see if I ask you a question what is heavier iron or cotton wool what would your answer be the correct answer would be that the question is incomplete makes no sense well iron is more dense than cotton wool that is true but suppose I drop an iron pin from a fifth floor and then I drop 5 kg of cotton which one will have more impact on anybody or anything that it falls upon definitely cotton so density of cotton is much less but then we are using a higher volume that is why the mass is more density of iron is more but we are using a smaller volume so mass is less so let us not confuse the extensive quantity extrinsic quantity probability with the intrinsic quantity probability density for s orbitals it is true that maximum probability density of finding the electrons is at the nucleus but volume is 0 as we are going to see in the shortish next module that we are going to have


Today, we shall begin to look at various kinds of engines that actually power their craft to flight. You have had a good exposure to various kinds of laws of physics. We began with the laws of motion, the Newton's laws of motion. Then, you had a full exposure to various kinds of laws of thermodynamics. These are the laws of physics which we shall refer to quite often when we look at the various engines, because many of these engines or all of these engines actually have to conform to these laws. If they do not conform to these laws, they cannot perform. This is the fundamental issue on the basis of which the engines are built and operated. It is necessary for you to understand that all the engines that we have today that are powering their craft are based on what is also known as heat engines. All these heat engines basically have to conform to all the laws of thermodynamics that you have been exposed to. Since they create motion of the aircraft, they have to conform to the Newton's laws of motion. So, we have to implicitly and quite often explicitly refer to those laws of physics all the time that we are talking about the engines. To begin with today, we shall start off with looking at the most fundamental and the most probably the ancient form of aircraft engine, the piston prop engine. The kind of engine that actually powered the first flight by the Wright brothers and almost 50 years thereafter, all the aircraft flew with piston prop engines. Even today, most of the aircraft that are flying around the small aircraft and they are actually more in number, most of them are flown with piston prop engines. So, even today, thousands of aircraft are flying around with piston prop engines and hence it is probably a good idea for us to take a good look at how the piston prop engines work. Basically, the piston prop engines have two components, one which is the piston engine which can also be called some form of internal combustion or IC engine and we will have a good look at this kind of engine basis, fundamental basis today. And later on in this lecture series, we will take a look at the propellers which are the thrusters which make the thrust. So, piston engine or the IC engine create the power and the propellers convert that power to useful thrust for flying the aircraft. So, we need two components and we will look at them separately. Today, we shall look at how the piston engine or the IC engine actually is fundamentally created, what is the basis and we will have to go back to the thermodynamics that you have exposed to. We have to bring back the concept of energy, the concept of work and how the energy is finally converted to useful work or power which can finally fly an aircraft. The piston engines that we will be looking at are based on what is known as auto cycles. Now, auto cycles are is the thermodynamic basis on which the piston engines are created. Now, auto cycle is one of the cycles on which various heat engines are made. Almost all heat engines that we know would be based on one of the cycles that you have been exposed to. The piston engine that we are looking at is based on what is popularly known as auto cycle. We will today look at the ideal form of the auto cycle as was originally proposed by the thermodynamicists and then we will look at the real form of the auto cycle which is how the piston engines actually work and what is the difference between the ideal cycle and the real cycle and this is what we will have a close look at today. As I mentioned, these cycles based on which the engines are made are also called internal combustion engines. Now, one of the reasons they are called internal combustion engines is because combustion is the method by which the energy is supplied into the system which we call engine. Now, that is the input from outside the system into the system and then the system converts that energy to useful work. So, conversion of energy to useful work is something you may have studied in the thermodynamics and this is what we will now explicitly make use of in actually creating the engines. So, we would be continuously making use of the concept of putting in the energy from outside in our case for example, by burning fuel through the process of combustion and then we will have to find a way to convert this energy which is released by burning the fuel into useful work and the mechanism by which it is done and finally, to convert it to what we can call mechanical work is what the whole engine fundamentals is all about. So, we will take a look at the thermodynamics of how the engine functions, the cycles and in the process we will try to understand how the thermodynamic concepts are finally used to make an engine that actually perform work which is useful to us finally, for the process of creating thrust which makes aircraft fly. As I mentioned all heat engines are conceptually based on one thermodynamic cycle or the other. It is necessary that heat engines conform to one cycle or the other, so that you always have a continuous process of control over what is happening in various legs of the performance of the engine and more importantly with the use of the thermodynamic principle, the thermodynamic laws and the mathematics that goes with it, you can actually predict pretty closely how the engine is going to perform. This is very important, it is necessary for a creator of engines to know very closely how the engine is going to finally perform and this knowledge is very important. So, it is necessary that they conform to one of the known kinds of thermodynamic cycle or the other, so that their final performances could be very closely predicted and later on closely monitored. As you know a cycle is made up of number of legs which are actually thermodynamic processes and they combine together to make a cycle. Now, each of these processes could be different processes, one could be constant volume process, one could be constant pressure process, one could be isentropic process, so on and so forth. So, they all made up together to make a cycle and we got to have continuous control over each of these legs or each of these processes when they are occurring and we got to have a prior knowledge of these processes, so that we can predict what is happening in each of these legs which make up the engine together. The other important thing is these cycles which we are using for making up the engines, they use or recycle the same working medium. Now, this is very important, the working medium we have in abundance around us is air and that is freely available in the atmosphere to us. So, all these cycles and all these engines have been created with the purpose of using freely available air as working medium, so that the bulk of the working medium that is used for creating work and in our case creating finally thrust is available in air and as a result of which all aircraft engines are essentially air breathing engines. So, we are looking at various kinds of engines from now onwards, all of them almost invariably would be air breathing engines. We shall see later on towards the end of this course when we look at the rocket engines, those are non air breathing engines. So, till we come to the rockets as long as we are talking about the aircraft engines, remember we will be talking about air breathing engines that use air as the basic working medium. The cycles as I mentioned are made up of number of processes and all of them have to conform to the thermodynamic laws that we have done. Each of these process is a thermodynamic process and they have to conform to the thermodynamic laws that you have studied over the number of lectures till now and remember that we will be using those thermodynamic laws quite explicitly and sometimes implicitly in understanding these processes which make up the entire cycle. Let us look at what is known as the ideal Otto cycle. The cycle essentially consists of six processes and let us start from the beginning. It starts from a point which may call A and from which we have what presently let us call intake of air and it starts from A and goes to B. So, the process A to B is called the intake of air. The air is taken into the system and from B to C this air is now compressed and this is called compression process and it goes to higher pressure over here as you can see in this PV diagram and then from C you have a burning of fuel this is combustion process. So, in the process of burning of fuel this compressed air is now raised in temperature to a higher level as per laws of thermodynamics when you raise the temperature the pressure also goes up. So, it goes to a higher pressure at D. Now, at this high pressure temperature the cycle now does the process of expansion. So, from D the process is expanded which is in engine terms is called power stroke and it expanded from D all the way down to E and that is the end of the process of expansion which is also called power stroke. And in the ideal cycle conceptually over here between A and B you can say that there is a certain amount of heat rejection which occurs from the system just like there was a heat intake into the system through fuel burning. There is heat rejection through various kinds of heat transfer and then the process reaches B and from B the air that has been inhaled is now exhaled and the exhaust of the air goes out of the system and then fresh air is brought into the system. So, this is the cycle the air comes in gets compressed the fuel gets burned then it is expanded the high temperature pressure air is expanded and then there is a bit of a rejection of heat into the out of the system and then the exhalation the air is exhausted from the system and this is the cycle which continuously occurs in this process which we call auto cycle. Now, if you look at a schematic of an engine which occurs which operates as per auto cycle. So, just below the PV diagram you will see this diagram here of a schematic of a piston engine. Now, what happens is when the piston this is the piston stroke as it is often called and this is what we were calling as stroke. Now, and this is the LP is the length of the stroke. Now, what happens is over here the end of the piston stroke 1 n is called BDC over here if you look at if you if you take the piston in a upright position the lower one is referred to as the bottom dead center and the top one is called the top dead center. So, the idea that is how the names were given that this is the bottom dead center and this is the top dead center the name stuck not necessarily the pistons are always in upright position quite often they are in horizontal position like this, but the names TDC and BDC have remained for almost 100 years and people continue to use those terminologies. Now, what happens is when the air is inhaled that is the process from A to B the piston actually moves downwards over here and this entire space is opened up this entire space is opened up. So, air from one of the ports over here comes in and fills up this entire space and then the process of compression starts from B all the way to C then the piston here head piston head as it is called moves from BDC towards TDC as it moves the air which was which had come in and had got captured inside this volume of the piston gets compressed to a much smaller space and as a result of which the piston now creates a very small space within the within which the air is now entrapped and is compressed. Now, this compressed air is then subjected to burning of the fuel. Now, this burning of the fuel then in this small space creates even higher pressure and of course the high temperature. So, this small highly compressed air when subjected to high temperature and pressure then exerts huge pressure backwards onto the piston head and as a result of which the piston is forced to move forward and that undergoes the process of expansion all the way from D to E and during that process the piston head is now moving backwards back from TDC all the way back to BDC. So, once it comes over here we have this process of heat rejection out of the system and then the process of exhaust start that means the piston again starts moving. Now, what we have inside here is a burned fuel and air mixed up. So, what we may call burned gas. So, this exhaust of the burned gas now starts happening as the piston head starts moving and this burned gas is exiled out of a port here. The port is timed to move to open up at this point of time and this burned gas now goes out through this port into the outside the system and then the fresh charge of fresh air starts coming into the body of the cylinder. So, this is how the cycle occurs the fresh air comes in it is time to open exactly when it is air is supposed to come in once it is come in this port is closed down and then the process of compression starts and then again the combustion and then again the power stroke and then exhaustion or exhaust of the gas burned gas out of the system. So, this is how the entire cycle actually operates that we have a continuous process by which the whole cycle does the same job again and again. Now if you look at some of these processes thermodynamically for example, the process AB can be referred to as a constant pressure process because during this process there is no change of pressure. So, this is what we call a constant pressure process thermodynamically. Now the process B to C is referred to as isentropic compression in the ideal cycle because this process is now occurring under a thermodynamic process in which the entropy of the system is say to be conserved. So, during this process there is no change of entropy as in visaged in the ideal cycle and the process of compression occurs along that and then process from C to D now this is combustion. Now this occurs under constant volume process and now during which as you can see in the PV diagram there is no change of volume and visaged in the ideal cycle and as a result the combustion is expected to occur in constant volume combustion process. At the end of the combustion we have the power stroke or expansion thermodynamically and this is again an isentropic process which means during which the process undergoes no change in the entropy which essentially means that the process is essentially a diabetic and no losses are occurring during this process. Same was the true for the compression that means these two processes are isentropic process during which there is the process is a diabetic and there is the no losses are envisaged in the system that means the two processes are reversible processes. So, they are reversible adiabatic processes which in short or in other words we call isentropic process. So, we have work done or power stroke which is isentropic work input or compression which is isentropic and then at the end of the process E at E we have a constant volume heat rejection from the burnt gas a mixture of fuel and air and then at the end of this rejection process we again have this exhaust of the fuel of the burnt gas from the system which is again a constant pressure process it is ideally envisaged to occur in constant pressure. So, all the legs that we have seen now can be now cast in the form of one thermodynamic process or the other that you have already done and hence all these processes are now conforming to various thermodynamic laws. So, we can now apply the thermodynamic laws to these processes and to the cycle as a whole to find out how this entire cycle is actually going to work because finally we want work out of this whole system. So, the entire process that entire cycle consisting of all these processes that we have now talked about have to now conform to various thermodynamic laws and all of them put together finally will tell us how the entire cycle which means the entire engine is expected to work in this ideal process as envisaged. The net area of the PV diagram in this thermodynamic cycle diagram is sought to be increased for maximizing the power output. Now, what we can see here this was the power stroke and this is the input stroke. So, this is the so called output stroke, this is the so called input stroke typically it is envisaged or it is understood that the area subtended under this is essentially the output work. So, the entire area under the curve D e is the output work on the other hand the entire area under the curve B c is the input work. So, out of the output work certain amount of work goes inside the system back again in the form of compression and hence the difference between these two areas that is the area subtended between B, C, D and E essentially now represent the work that is available for doing some useful work that is in our case it will be used for creating let us say thrust or making the engine work. So, that is the useful work that would be available or often thermodynamically or in simple terms referred to as the network. So, the gross work done by the power stroke minus the work input of the compression stroke is the network that is available. Now it stands to reason then that every engine designer would try to create a thermodynamic cycle in which the power output is if it is to be increased the net area that is available in this p v diagram is to be maximized. How to do that that is another story, but the designer of the engine he has to design a cycle first. The engine designer needs to design a cycle first and that cycle design needs to concentrate on the concept of increasing the p v diagram the net area of the p v diagram. So, that the work output expected can be maximized. Now how do you do that? So, the idea is if you want power output maximized you got to have a change of specific volume or the increase of pressure or temperature through the cycle. So, if you look at the cycle diagram you are trying to increase this volume. Now if you want to increase this volume there are two or three simple ways one can do it the length of the stroke. So, to say can be increased by which you can increase the volume or the difference between compression stroke and power stroke this vertically can be increased which requires that the point D is to be raised to higher level and the power stroke occurs at a higher pressure and compression stroke occurs at a much lower pressure. So, those are the you know ideas by which the cycle can be designed to maximize the power output from this system. So, what it requires then is you have a large change in volume which shall require then a large size engine. The large change in specific volume shall also require large change in pressure and which requires again a large change in volume. Large change in temperature shall require large input of fuel or fuel of high heat release capacity. So, these are the means by which you can try to increase the work done of the system. The some of the troubles that we have is that if you want to increase the volume you want to increase the size of the engine it may have some limitation when it comes to the use in aircraft. So, those are the limitations which will again look into later on, but if a cycle is being designed to create an engine these are the issues that the cycle designer the engine designer will have to look into will have to contend with for designing engines that create certain amount of power or a maximum amount of power under given operating condition. Let us try to understand how the auto cycle analysis can be done to quantify some of our needs. We need to quantify some of the parameters that we are talking about. Now, this is the cycle we have just had a look into and this is where the heat is coming in the fuel is being burned and the heat is coming in and this is where we assume that certain amount of heat is being given out of the system which could be called q 2. So, q 1 is the heat that is coming in. So, now understand that not withstanding this long compression stroke and power stroke the input to the system is through here and output through the system is from here. So, the heat input q 1 is in a constant volume process is given over here it depends on the temperature level from here to here and the heat rejection is from here which is the temperature differential between this point and this point. We make all these points 1 2 3 4 and we shall be doing that again. So, this gives the heat input and the heat output of the system. What the power stroke does is converts the heat of the energy released by the fuel burning and the pressure that is built up by the compression stroke to mechanical work or mechanical motion. So, the net work that would be available from this cycle is q 1 minus q 2 and this is the work done by the power stroke minus the work done by the compression stroke what we call the net area that is available in this cycle between B C D E and that is the area that we are looking at in terms of the work done or what available from this cycle. If you look at the cycle you would probably see there are number of parameters that one can create to characterize this cycle. These are often called the characteristic parameters of the cycle. The first one is the compression ratio which is the volume ratio between V B and V C that is the compression ratio under which this cycle operates and it is simply called this volume ratio is simply called the compression ratio. The other is the pressure ratio that is between you know the pressure that is occurring between this line and this line and this is referred to as the pressure ratio. We shall see later on that this pressure ratio has greater importance in other kinds of cycle. In this particular cycle the compression ratio is a more important item and then the temperature ratio that is the maximum temperature which the cycle experiences starting from the starting temperature this is often called the cycle temperature ratio. So, this is the cycle compression ratio and this is the cycle temperature ratio. So, every thermodynamic cycle is actually very sensitive to these ratios because these ratios we shall see as we go along actually decide the work capacity and the efficiency with which this work is accomplished. So, these ratios are extremely important as I mentioned they characterize the cycles they are the characteristics of the cycle and the cycles are often mentioned in terms of compression ratio temperature ratio and later on we will see in case of open cycles other kinds of cycles the pressure ratio. So, some of these ratios would be coming back to us as important parameters and as you can see they are non-dimensional parameters and they are very important in terms of trying to prima facie find out what could be the efficiency of some of these working cycles. Let us look at the ideal auto cycle that we are at the moment trying to understand that is a cycle that we have looked at and as the compression and the expansion processes as we have seen are isentropic we can use the isentropic laws that you have studied and then we have the combustion and the heat rejection processes which are constant volume processes and we can use the thermodynamic laws that you have used for those kind of processes and if we use all of them the and we can sit down and do a simple derivation what you can find is the cycle efficiency can be written down this is the thermal efficiency of the cycle it can be written down in the in terms of the compression ratio of the volume ratio and the specific heat ratio that is of the working medium that we are using in our case that is air. If we if we have just these two values available with us that is the compression ratio and the specific heat ratio of the working medium we can quickly find out what the cycle efficiency would be. So, you see it is quite simple that if you prima facie have the compression ratio available with you you know the working medium that you are using you can quickly find out what the cycle efficiency is likely to be and as we as we shall see this allows the cycle designer the engine designer to indeed configure a cycle or configure engine even before it is actually built. Using this for example, we can put down some numbers this is the compression ratio for example, the cycle designer or the engine designer is trying to build and if you have these kind of values these are the thermal efficiencies with which the engines will work. Now, I have used here two different specific heat ratios 1.35 is what is quite often used for hot gases or when the fuel has been burned quite often that is the kind of values used 1.4 as you might know already is normally used for simple air. So, if you use those specific heat ratios you get various values of efficiencies and as you can see here as the compression ratio increases the efficiency of the cycle and that of the engine actually increases. If you have a pure air of course, the efficiency is a little higher, but as you know we have to burn fuel to put in the energy into the system and hence this is the kind of value that we are normally likely to encounter in actual engines and that gives us an idea to what extent you can have high compression ratios to get higher and higher energy efficiency of the engine. What the compression ratio can be depends on number of parameters or number of practical considerations and we shall be talking about some of that as we go along in this lecture and in the next lecture. So, the cycle designer has an idea now that if he chooses certain compression ratio and given the working medium he would be able to attain certain kind of cycle efficiency which he hopes to come pretty close to in an actual working engine. Now, the PV diagram that we have looked at can also be you know recast in the form of what can be called what is often called the TS diagram which is of course as you know the other way of diagrammatically representing a cycle. So, cycle is often represented either in PV diagram or in TS diagram and in this case if we cast the auto cycle in the form of TS diagram to begin with for example, we have written down the efficiency thermal efficiency all over again and in the TS diagram we can now see that the work done for example, if you take the first cycle here 6, 2, 3 and 5 and that is the work done of the system or the heat input into the system and heat output Q 2 is in terms of 6, 1, 4, 5. Now, TS diagram directly tells us the work the heat input and the heat output of the system and as a result of which the thermal efficiency can be quickly found and it tells us again that the net area that is 1, 2, 3, 4 actually gives us the net work output or net energy available for work divided by the net work input or net heat input and that is thermal efficiency of the system. Now, let us consider in this TS diagram another cycle which has same net area as the first one that is area 1, 2, 3, 4 is same as the area let us say 1, 7, 8 and 9. So, these two areas are exactly same. So, two different people let us say have configured two different cycles and the net area of both of them are actually same. So, let us say two designers have created two different these two different cycle what happens is in the second cycle which is you know 1, 7, 8, 9, 1 this actually would have a higher efficiency and this higher efficiency is because this area 6, 1, 9, 0 is actually less than the area 6, 1, 4, 5 that means the heat rejection in the second cycle is actually much lower and as a result of which the area 6, 7, 8, 1, 0 that is 6, 7, 8, 10 really 6, 7, 8, 10 is actually higher than it is also the area 6, 7, 8, 10 is lower than the area 6, 2, 3, 5, 6, 2, 3, 5. So, as a result of which the efficiency which is now given in terms of the net area and the heat input into the system the because of the fact that the net area of 6, 1, 4, 5 is actually higher than the 6, 1, 9, 0 the efficiency of the second cycle comes out to be much higher which means if you can do the heat input at a higher pressure, now this is the higher pressure line in the T S diagram, 7, 8 is a you know pressure line, constant volume line sorry and that constant if you can do that the heat input at a constant volume line you can get a higher efficiency of the system even if the area net area is same. So, which means the cycle design or the cycle designer who looks into creating the cycle has a very important role to play in finally creating the engine that finally is out of various kinds of materials. So, the conceptual cycle that the auto cycle is designed on creates the engine and a lot of thought needs to be given to creating the auto cycle which finally creates the piston engine that works and that supplies power for creation of thrust. Let us now take a turn our attention to what could be called the real engine or the actual piston engine according to which the actual engine would work. Now, some of these things are born out of the understanding of how the piston engine actually works and as a result of which we shall see here that the what we can call now a real cycle let us say conforming to some piston engine differs quite a lot from the ideal cycle. The difference is for example, you can see the net area that is created by the real cycle seems to be substantially less than the net area that was being created by the ideal conceptual cycle. This is due to the fact that the work which is being done during the expansion compression process quite often are not isentropic. You remember we had assumed that the processes are isentropic and as we shall see as we move along more and more that these processes cannot be isentropic quite often they can indeed be adiabatic they can be pretty closely adiabatic but quite often they are unlikely to be reversible processes. So we are going to have processes which are mostly irreversible processes which means they undergo certain amount of loss. This loss is in the form of loss of energy and as a result of which the net work that is available outside of the system out of the system is going to be much less than what is conceived in the ideal cycle and as we shall see here that the intake and exhaust processes are not on the same pressure line. These are the reasons because of which the real cycle differs quite a lot from the ideal cycle. Let us get into them a little more in detail. The intake of the fresh air let us start from the intake often happens at a pressure which is 1 to 2 and which is often a little lower than the ideal cycle and as we shall see later on that the exhaust often happens at a pressure higher than that of the ideal cycle it starts from here and it goes around here and then this is how the intake occurs. Now this is how the air is driven out of the piston and this is how the piston actually takes in the air and as a result of which there is a slight difference between the exhaust stroke pressure line and the intake stroke pressure line and it creates a certain amount of work that goes away in the process of exhaust and intake and that would not be available to the external agency which requires that work for creating thrust for through the propellers. So, the intake and exhaust do not conform to the ideal cycle concept. Now let us look at the compression process. The compression that process quite often since the intake process finishes its intake line at 2 which is as you can see a little lower than b. The compression process starts at a pressure which is lower and quite often proceeds along a line a centropic line which is a little lower and as a result of which it quite often and as a result of the fact that it does not conform to the reversibility and it encounters certain amount of losses due to the motion of the piston inside the cylinder. It does not quite reach the point C the compression process often goes up to C up to 3 and then at 3 the combustion is initiated. So, the compression process the only compression process as we know goes from 2 to 3 and at 3's a combustion is initiated and this combustion starts at 3. The compression actually continues a little it goes to what we had called TDC in the piston and then the combustion process continues up to 4. So, the pressure and temperature keeps on rising and then over here the expansion process starts. So, the process of combustion as you can see quite often due to the process of either incomplete combustion or due to the fact that the movement of piston has somehow come in the way it never quite finally reaches the point D somehow or other it finishes off at somewhere around 4 and then the process of expansion or the power stroke starts. This expansion process now starts as you can see quite often summer over here which means the expansion in some manner has started even before the combustion process is actually completed. And from here we can officially say that the expansion has started now by now the fuel has been burned and we have a mixture of fuel and air and then this power stroke starts at pressure 4 and this high pressure now moves the piston down to 5. And as we can see slowly that it finally you know it starts at a pressure lower than D it finishes off at pressure eventually which is lower than E. And over here as we shall see that the power stroke actually takes around over here quite often you do not have much of a time really for the heat rejection process which is ideally conceived or envisaged and as a result the process the exhaust process starts right away here. And the heat rejection process which is shown from E to B or E to F is quite often very quickly almost instantaneously rounded out over here. In fact the exhaust gas that is going out carries away the heat. So the heat rejection often happens with the exhaustion process and the exhaust gas or the burned gas that is going out actually carries away a lot of heat. So the ideal process and the real process as you can see happen quite differently because the motion of the piston the burning of the fuel all of it together finally creates what we call the real cycle. And this as a result of which the exhaust process is completed when it reaches 6. Now this often occurs now you can see at a pressure which is at a higher pressure it starts off actually as I mentioned over here you know a little after 5. And then as a result of which it settles down at a pressure which is exhaust pressure which is at a higher pressure than the ideal pressure envisaged and it ends up at 6. And then the intake process starts all over again. So the whole cycle of the engine starts all over again. So this is how the real cycle operates and this is how the real cycle is quite often different from the ideal cycle. This particular cycle was initially used for creating the what is known as two-stroke engine. Various kinds of two-strokes engines are operational even today. However the two-strokes engines are not used in aircraft power plant anymore and all the modern aircraft engines use what is known as four-stroke engine. Now very quickly the two-stroke engine what used to do or wherever they are used even today they kind of combine the intake and power stroke and then they combine the compression like exhaust stroke and somewhere in between the combustion is expected to occur in a very short time when the piston is at you know TDC. So this is a kind of hand-drawn sketch of a two-stroke engine. So when this reaches the top over here the combustion is expected to occur and then the power stroke would occur and when the power stroke occurs the intake also starts coming from this side. So this is the side from which the intake comes and when the compression stroke occurs the burned gas is simultaneously exhaled, exhaled out of the system. So this is called two-stroke because the two legs of the cycle are combined together into one stroke and as a result this engine operates on a two-stroke principle whereas as I mentioned most of the engines today are four-stroke. So from now onwards the cycles and other forms of engines that we look at would be four-stroke engines. This is a kind of four-stroke engine that is used in the modern aircraft engines all kinds of modern aircraft engines. Let us quickly understand how the thermodynamic processes are converted to what we call now strokes. The familiarity of the engine very quickly we have an intake valve over here which opens this intake port through which the fresh air comes in and there is a timing given. So this intake this has to be timed properly and air comes in through this and comes in and fills it. So when this is at the bottom what we call BDC and the piston is going down in the intake process this entire space is now filled up by the air coming in from here and this valve is open. Once the air is filled up over here and once the compression process starts that means the piston starts going up this valve closes. So this air cannot go out from anywhere anymore and it is entrapped within this space of the cylinder and now the piston is moving up. So this entrapped air is compressed in this enclosed volume. Once this moves right to the top and it reaches the top dead center the fuel is burnt and we have a spark plug over here which initiates the ignition process and the as a result of which the combustion occurs over here. This combustion creates the high pressure and the high temperature and the high internal energy level of the air and the burnt gas which then pushes the piston backwards and what we call then have the power stroke. So then the piston again starts moving backwards it pushed backwards by the high pressure or high internal energy and it creates the power stroke. Once the power stroke is completed by that means the piston reaches the bottom dead center the piston then starts moving upwards again in the form of inertia of the system and then this outlet valve is opened. This outlet valve is opened it is time to open when the piston starts moving upwards after the power stroke and then the burnt gas now this is closed. So this is burnt gas the work has been taken out through the power stroke and then this burnt gas goes out of the cylinder altogether and this reaches top dead center and almost the entire amount of burnt gas is now moved out of the system. What does happen is a very small amount of burnt gas actually stays back. So when the fresh air is coming in it mixes with the burnt gas and as a result of which you do not actually have fresh air from the second cycle onwards you always have a residual burnt gas mixing with the fresh air and as a result of which as we have seen the real cycle operates slightly different from the ideal cycle. So this is another reason why the real cycle differs from the ideal cycle. So this is the mechanism this is the mechanical mechanism by which the cycle is converted to an engine and now what we are looking at is a picture or a diagrammatic sketch of an engine by virtue of which you can create work or mechanical work and this engine then moves the crankshaft over here this is the crankshaft which creates the motion rotary motion and through the shaft power is taken out on a continuous basis for running any working body in our case that would be the propeller which creates thrust. So these are the details of a working engine and some of these are what we will be looking into in the next lecture as to how an engine of this kind is finally converted to an aircraft power plant. So our next lecture will be on converting or arranging some of these engines into various kinds of useful power plants that can be used on an aircraft which finally will create thrust and our business is finally creating thrust. Engine is the method by which we create power and we have just looked at the thermodynamics of the engine. In the next class we will look at the arrangements of these engines in the form of aircraft power plants.


MGN. We don't play games with your YouTube gaming career. Hey guys, Nate here. For today's show we have Ben French, the head of MGN. Good to have you on the show Ben. Tell us about yourself. Where are you from? I suppose I'm from Norway, though I am half British. I grew up in Stattella, Norway, till I was 11 years old and then my family and I moved to Bridgewater here in the UK.  As the head of MGN, what do you do around here? I make sure everyone knows what they're doing. Essentially I am the glue between all the staff at MGN. I keep everyone up to date with the changes in MGN and I have a hand in every project to make sure the work gets done. So you're saying you're the hoof slime of a dead horse? Guess I can't really argue with you there. How did you get to where you are today? I joined MGN at the beginning as a business partner making games and videos. I saw a need for live streams so I jumped on that too. After some recent restructuring I put forth my ideas for MGN and ended up as network manager. What would you like to see happen with MGN in the future? I would like to see more partners join of course. We try to do our best for our partners and it would be pretty sweet to have more people to slap in the face. Yep our slapping muscles would definitely atrophy without more faces. Any personal plans you're looking forward to? Right now I'm busy with MGN but eventually I would like to own my own video game development studio. So Ben we ask this to everyone what's your favorite game? Telltales The Walking Dead. This game made me actually care about the characters. It really lets you feel how good it feels to feel. Now Ben we got one final question for you and this one's a doozy. I have two cats I like to fight. I have my suspicions that it's the excessive amount of pepper that I put in a cat food. Do you have any clue how I could show them that there's more to life than fighting? Well Nate I would sit the cats down at the table of equity serving the turducken of tranquility as a piece of her. They would have to meow their apologies to each other and accept that sometimes their food will be spiked with mace and that's okay. Everyone's different. That's what makes them special. True words of wisdom from our MGN commander Ben French. How would you solve this cat conundrum? Tell us in the comments below. Nate signing out. Have a good week freedom family. Fluffy minute stop fighting.


Coming up on DTNS breaking news about breaking galaxy fold Z's how to get a ride into space in the next couple of years even if you aren't an astronaut and Should we raise cows on the water? This is the Daily Tech news for Tuesday, February 18th, 2020 in Los Angeles. I'm Tom Merritt and from studio Redwood I'm Sarah Lane and I'm Roger Chang the shows producer. We were discussing a little text message etiquette Is it okay to just say hey and text message if you want that and Discussions of ice cream and more go get good day internet the wider show at patreon.com slash DTNS Let's start with a few tech things you should know Bloomberg reports that launch of a new low-cost iPhone SE is still on track to happen in March an updated iPad Pro with a New camera module could still be delayed or constrained Outside possibilities also include an updated 13-inch MacBook Pro a new MacBook Air air tags trackers for your items that work on Ultra-wide band and a wireless charging mat TfSecurities analyst Ming-Chi Quo sources say that Apple will ramp up production of air tags in Q2 or Q3 of this year Yeah, we figured out why Nvidia and Activision Blizzard were fighting and it wasn't because what's gotten I thought last week verge reports that it was a Misunderstanding between Activision and Blizzard over the GeForce now service and video thought it had permission to keep Battle.net games going during the free trial But it was mistaken Bloomberg sources say Activision Blizzard wants a commercial agreement Which would mean maybe having to pay twice and Nvidia doesn't want any commercial agreements Regarding our speculation that this had to do with stadia it appears not an Activision Blizzard spokesperson told the verge that the company is focusing quote specifically on YouTube and Google Cloud Microsoft release it's all-in-one office app for Android to everyone the app combines Android versions of word Excel and PowerPoint it lets you browse files in one drive It also syncs with Windows 10 notes and includes office lens scanners and a QR code reader The app is locked in portrait mode and has no UI for tablets or Chromebooks And a report in nature describes a device called Air Gen Created by electrical engineer junior and microbiologist Derek lovely at UMass Amherst that generated electricity from the moisture in the air This could be big electrically conductive nanowire produced by the microbe geobacter Interacts with naturally present water vapor to create current They say it works even in low humidity conditions like those found in the Sahara Desert You don't need it to be in a particularly humid place The Air Gen can power small electronics right now like your wearables and should reach commercial scale in productivity fairly soon So keep an eye out for that. That's amazing Dell announced its selling RSA security to a private equity consortium for 2.0 75 billion dollars The transaction includes RSA Archer RSA net witness platform RSA secure ID RSA fraud and risk intelligence and RSA conference the sales expected to close in the next six to nine months And Kickstarter employees voted 46 to 37 to form a union with the office and professional employees International Kickstarter workers are the first white collar workers at a major tech company to successfully unionize in the United States There's been like Food workers at Google and other tech companies that have had unions But this is the first in the in the white collar tier Kickstarter CEO Aziz Hassan said in a statement We support and respect this decision and we are proud of the fair and democratic process that got us here Doesn't say whether he had his teeth clenched or not. All right. Let's talk a little bit more about a new Qualcomm modem Oh, let's Qualcomm unveiled its 5 nanometer snapdragon x60 5g modem Which he says which it says is the first to offer carrier aggregation for signal sent over sub 6 gigahertz and millimeter wave variants of 5g networks This would let a carrier send data over multiple bands at once leading to faster speeds overall samples of the x65 5g modem will go out in q1 and are expected to show up in phones in early 2021 Yeah, this confused me at first when I saw the headline come across the feeds Because there is a Qualcomm modem out right now that supports millimeter wave and sub 6g sub 6 gigahertz But the phone can only use one at a time It can switch back and forth even on the same carrier, but it can only connect to one at a time this new x65 g modem Can bond to the connection so essentially it can send the data through both the millimeter wave and The sub 6 gigahertz and whenever you bond a connection like that you you effectively raise the potential Capacity and the potential speed so that's a pretty significant thing. It's it's interesting that we're gonna take a year to get this into phones But it's not gonna be something it's gonna be hard to market this It's you're just gonna say like with a faster modem connection and carriers are gonna have to write Exploit it. It's hard to make this like a one-liner marketing thing. Yeah, we're like, I don't know or my speed's faster Qualcomm's like yes, but there's more to it Yeah, so yeah, how is this gonna work Qualcomm is gonna sample these out Manufacturers are gonna work with the carriers who can do this some carriers will want to do carrier aggregation some won't You know something like Google Fi Might be able to to use this then they're gonna say, okay, these devices these manufacturers will make them partnered with these carriers And then it's gonna have to come from the carriers I think I'm sure some announcements from from device makers might mention that they have the ability to do carrier aggregation with the x65 g modem inside But you're gonna have to get a carrier that takes advantage of it for it to be worth bothering with Yeah, I mean the fact that Qualcomm is the first is significant But really this just means that Eventually, this is something that that carriers can take advantage of and consumers will benefit from I'm hoping more carriers do this They don't always because carrier aggregation isn't new you could do it on 4g you can do it on on 3g and even 2g And in fact the x65 g as you mentioned on daily tech headlines today can handle all the way back to 2g So you could aggregate all over the place. Yeah, the carriers don't always want to do the work for that One of the elements of Samsung's foldable galaxy z flip was that it uses glass instead of plastic in the screen Which implied that maybe it would be more durable However, it does not appear that it is Extremely durable. Well, let's review YouTube reviewer Zach Nelson Does a regular screen test where he takes progressively more destructive things, you know Like a pen and then you know up to a Cardboard cutter to the screen to see if it can scratch it He has levels that that he has calibrated Most smartphones don't show scratches till he gets to level six or seven He's reusing some really sharp stuff the galaxy z flip started showing scratches at level two now Samsung told the Verge that the ultra thin glass Used in the galaxy z flip has a protective layer on top Implying that the scratches seen at level two are similar to scratches seen on plastic screens because it's that plastic layer on top That's getting scratched Samsung said it will offer one-time free application of a screen protector on the z flip And has a screen replacement program where you pay 119 bucks to replace your screen if it breaks speaking of breaking there's some reports of Cracking of the screen nothing with the hinge in this one, but a twitter User cracked a z flip right out of the box thinking it might have been because of the cold weather And senets three-foot drop test shattered the glass as well again The hinge seems to be fine in this thing and it's not like these things are breaking all over the place Right and left, but they aren't holding up to the same level of durability tests that a normal smartphone would hold up to Yeah, before the show I was you know My takeaway was sort of just like are we just trying to make this new form factor happen? And it's not going to happen not making flip happen But at the same time you bring up a good point tom and roger had said the same thing too that If if there's if there's a certain form factor under so much scrutiny That there are all these tests being done to be like and look there are scratches on it It's like I mean my phone is scratched in lots of places because I just dropped it out of my pocket I mean it's not as if the you know the flat form factor has been You know great to me I like the idea of something being able to fold shut I think in general that actually is the safer way to go about things, but again These are early days and companies are trying to figure out what the what the sweet spots are Yeah, this is a great example of headline creep of outrage creep Where originally the problem with the galaxy fold was the hinge was breaking and there was a problem with the plastic screen This is a different problem. It's a problem with the screen being scratched or the glass breaking and People are sort of seem to be equating it to the galaxy like oh, it's just as bad as the galaxy fold and it's not It doesn't doesn't mean it's good. We could we have to have you know more than two approaches to to understand this properly It's not good. In other words, it's not going to be as durable as your current phone But your current phone isn't perfectly durable And yet it's also not as bad as this thing breaks all the time It means if you buy a galaxy z flip you need to be gentle with it And if you're the kind of person who's hard on phone screens, maybe it's not the phone for you Yeah, I mean that's a really good point, uh the especially when you get into these premium prices It's like you know someone be like oh what do you expect? What do you want to throw it around and it's just not going to break it's like this is this is a A precious delicate item does a lot of stuff. I make your life better got to treat it with care it's like someone who would Take a phone from say like the old the old the old flip phone and then compare it to a smartphone where You're just doing a drop test with that. It's like oh, I've dropped my flip phone I've dropped my flip phone out of a first story or second story window And it broke the the battery came out, but I could put it back together and it ran just fine I couldn't do that with my smartphone and I'm not going to say oh my smartphone my actually my pixel 3a is Defective because it's not survived a two-story fall Right, exactly. It's just a different kind of phone. You just have to keep that in mind All right guys, would you like to go to space? Is that a threat? Well depends depends. I'll read you the rest of the story. SpaceX plans to send four private citizens Could be you into orbit at the top of 2021 or early at the end of 2021 rather or early 2022 Space adventures, which has helped seven private citizens visit space will help with this project The tourists will fly in a dragon capsule at around the same height as the international space station Orbit two to three times and then return back to earth The first crude dragon flight is supposed to take place with nasa astronauts on board later this year Now SpaceX also has a contract with Japanese billionaire yuzaku Misawa to fly around the moon on the future big falcon rocket In fact, that's been in place for some time, but hasn't happened yet Both both blue origin and virgin galactic are planning suborbital flights to let paying customers Experience weightlessness, but this is a little bit beyond that Yeah, they're going higher than blue origin or virgin galactic virgin galactic still says they're going to do theirs by the end of the year The the the flight around the moon was supposed to happen in 2018 It didn't there's no date on that yet But because they're actually testing the dragon capsule with astronauts Seems possible that you could have private citizens going up in this thing at least in 2022 and if virgin galactic is Starting to do its tourist flights into sub orbit for weightlessness if blue origin starts doing their flights next year by The you know two years from now It might be a luxury item, but the idea of being able to pay to go into space as a Joyride might be normal It might be a thing that is you know accepted rather than a weird thing That's only happened a few times because of that company space adventures. Yeah, and so the the next Obvious question and I have I've been on the show in the past and I know people Go ahead and flame me if you like I have no desire to go to space I am never going to do this the the idea Fills me with anxiety. I just want to stay on earth where I belong But for people who do want to go how much is it going to cost? And how long are you up there? And those are questions that we don't know the answers to yet. Well two to three times orbit You're not up there for very long. Uh virgin galactic blue origin They're just going sub orbital to get you a little wee I'm weightless and then back down. So none of these are very long, but how much Yeah, uh, if you have to ask you probably can't afford it Exactly Yeah, no, and it's I will add this uh in some ways is the next step from the current level of Exotic ride for a lot of money where you can fly into so uh an ex russian air force fighter And they take you to the edge of space and a pressure suit and stuff and it lasts maybe an hour But I mean you pay a big stack of cash, but you get to brag I went to the edge of space in a in a in a russian That's what virgin galactic is doing same same type of thing. Yeah, so it'll be interesting to see all the humble brags when this comes around Yeah, I I am skeptical that all of these plans will happen on time. That's why I say How about cows on a boat? How about it? It's actually not a boat though. Wired's laura maloney has an article about a floating cow farm From a property development company called belladon in roderdam harbor in the netherlands The aim is to demonstrate a possible sustainable food source The idea came to the owner of belladon peter van windgarden when he saw the disruption to the food supply In new york during hurricane sandy and he's like maybe for food security. We should develop floating farms So he did a 4943 square foot stable floating on concrete pun tunes anchored into the seabed Cows eat potato peels and grass clippings waste is turned into fertilizer for park grass Like soccer fields or just you know meadows That then provides the clippings for the food and milk from the cows is bottled or made into yogurt The farm appears to be too expensive to replicate and widely or to replicate widely anyway And relies on too many resources outside of the cows. So there's a lot of maintenance when you're out on the seawater Power it doesn't make its own power. I know, you know, you're thinking cows Obviously, there's a power source there in methane, but they haven't figured that out yet So to maintain sustainability is a challenge But belladon founder peter van windgarden hopes the experiment will spark more creative thinking about food sustainability Yeah, and for anybody who's like well, you're putting a bunch of cows on a pontoon That's mean the cows can come and go This is a almost 5,000 square foot area for the cows to eat and it's the state do their do their business But they they can they can go uh to to and from land. Um, if they have a ticket If they're rich enough, but uh, but and also who's interesting I guess in the early stages of testing this out the a large question was Do the cows want to do this because if they're gonna get seasick like let's not do this to the cows Cow seem okay. Cows are like, all right. We we got it. You know, they're they're pretty resilient creatures, but uh, it it's interesting to me that This would be so Expensive to replicate. I understand that if you don't I mean the Netherlands is, you know below sea level majority wise and you know covered in water So this is a perfect place to try something like this out There are lots of other places in the world where this would work and and places that it wouldn't So you can't just say, yeah, we're just gonna, you know, build all the stuff, you know Every little lake around here. Of course that wouldn't work But uh, I I wonder what is so cost prohibitive at this point It's it probably has a lot to do with power But but as I mentioned the maintenance, you know, uh seawater Corrodes things you have to do a lot of maintenance to keep just a regular old boat in shape Or you know an oil derrick And and so you don't have any sustainability in that stuff Uh, there's not sustainable power There's not, you know, the cows don't provide any maintenance. So you have to pay other people They're not earning their keep. I mean it could go it doesn't necessarily have to be cows either It could be like a hydroponics Set up your growing crops But it would be the same maintenance and power Issues probably maybe less power. I don't know less power I mean if you can get some uh, if you can get some solar cells on top You can actually do kind of some sort of preventive galvanic corrosion on the vice by running a current through Uh through the superstructure see That's what peter van windgarden is hoping people will do by doing this this way He's like maybe maybe i'll inspire roger chang to improve on my design I I think if this might be a better fit for aquaculture, whether it's something like Raising oysters, you know a mobile floating oyster bed that you're not tied up next door But you let float and then let the waves carry in whatever Or there's already stuff like that with oyster beds, but yeah, there's those oyster beds Are are currently fixed like they're fixed from offshore. So you walk down and but if you could have it floating you could Well, these are fixed too. They're fixed to the well, I mean, that's that's my thing It's like if they could get it so you could have it float you could lessen the impact of things like fish farms and stuff to have currently and uh in shore areas Well starting this week ring will require all users humans or cows to use second factor Authentication when logging in users will be offered text message or email to receive a six digit code Ring also introduced new options for controlling when data is shared with third parties You can turn off sharing data with companies that create personalized ads as well And data sharing with analytic services is paused while ring works on an opt-out system That's going to work best for everybody last month ring added a privacy dashboard and options to control whether or not police can request footage This is all damage control for ring Ring is being pushed into doing these kinds of things because people are very upset at ring for Sharing third party data without making it absolutely clear not letting you control or opt-out So they're doing the right thing. They're saying, okay, we're not going to share analytic stuff till you can opt out We're going to let you turn off data sharing for ads If you want and we're just going to force you all to use second factor When when the verge talked to the ceo of ring about this it's ces He was implying it would be something that you could opt out of but it's not There's just from the sound of it going to make everyone get a second factor either by text message or email And use that every time they want to log into ring which Okay, that is going to force security on people so There are problems when you force security on people where people try to get around it or just stop using a product but That is going to force security. It's not as good as allowing actual ube keys or code generators But it is better than not having any security on your ring account And of course if your email is not Also protected by 2fa Then you really are just pushing, you know kicking the can down the road with the security vulnerability being on your email at that point They could still get into your ring account theoretically But you know These are all small steps in the right direction. Yeah, I agree. I I We've talked quite a bit at length of of rings Missteps, you know, it's it's not even I think a lot of folks are quick to say Oh, and I'll look at they're doing with the government and that that may be true Maybe not be true, but all of these steps are in an effort to gain back Trust from their user base. So yeah, it's it's all it's pretty pretty cut and dry I think there's some misunderstanding that police could go in and get footage out of your ring without your permission They couldn't uh, what was happening is They were allowing police to request footage in a way that a lot of people felt they had to agree to or they would Be suspicious, right? Uh, so is that power imbalance and saying look, I just don't want to be asked I don't I don't want to participate Is is an improvement For ring where they're saying look, we just won't let the police we won't let the police know your ring doorbell is even there Uh, and that way you won't feel pressured if they come along a lot of people very happily Want to cooperate because they have good relations with the police in their neighborhood and they're not suspicious of it Depends on who you are in one neighborhood you're in though Well, when it comes to ads kind of same story, right? Some people are like well, if i'm gonna see ads anyway They might as well be personalized If you you know if you if you know what I might like that would be helpful rather than not helpful at all other people Are like nope don't want to that should just always be an option for the user All right, uh these days it's hard to go through tech news without touching at least on the coronavirus in some way Uh, and we've got a few different points to get to here supply chain analytics provider trend force Has revised a report on smartphone production Uh, which is now projected decline 12 percent year on year in q1 Due to issues with the coronavirus making it the lowest quarter in five years It had been expected that smartphone production would bounce back in q1 after sort of going flat So this is unfortunate for the smartphone industry Uh, apple warned monday that it might not reach its previous q2 revenue guidance of 63 to 67 billion dollars Due to the effects of the coronavirus on its supply chains Manufacturing is resuming in china more slowly than expected according to apple So apple said the worldwide iphone supply would be temporarily constrained and that directly affects you If you're looking for a new iphone there might not be one on the shelf It might be harder to get one And of course it affects apple sales because in china itself apple stores remain closed or at reduced hours So they they just aren't as many opportunities for people to go buy an iphone People aren't leaving the house as much anyway because of the scare apple did not offer any new quarterly guidance numbers Other than to say that they would be affected Xiaomi also announced an expected impact to its sales Interestingly samsung is expected to feel less impact as half its smartphones are made in vietnam And it already had poor sales in china So people shopping less in china doesn't affect samsung as much because they just weren't selling it as much to begin with Uh, and their supply chain should be less impacted because the factories where they have their their stuff made Uh, aren't in the region directly impacted There's been a little the impact on cross border sales a lot of the components That go into the assembly in vietnam come from china and that's been impacted But overall vietnamese factories for samsung have been churning out Units, you know close to what they expected Yeah, as this story has unfolded and it's been it's been a weird one I you know, I have friends who are going to south by southwest in austin texas in march And you know, they're sort of like is it going to get cancelled too? And I was like, I don't know why it would Yeah, the you know the Mobile world congress would make a lot more sense But but okay this kind of like lasting effect of this and how much it actually does damage More than the next quarter ish especially for a company like apple I mean it was big news this morning apple saying hey, we're not going to meet our guidance We're not going to tell you what we think it's going to be But it was already kind of a wide range and we're just not going to make it We know we won't that that's a big deal because it's apple But how much does this really become a ripple effect? More than the next three months. Yeah the the the general consensus You know, I read the economist listen to the economist bbc at such is that you know outside of technology This is outside of my expertise, but the general consensus seems to be Usually when this sort of thing happens Yes, there's a downturn because of lack of consumption and production But then there's an upturn afterwards because people were just deferring Until after and so you get a spike But the spike is never enough to fully make up the difference Yeah, and so the question is the longer it goes how much of a difference are you going to have between what was lost And the bounce back effect What what ends up with people just pushing off and saying look i'm just you know I'm not going to buy that phone or more relevant like you were saying with mobile world congress You don't go back and do mobile world congress everything that was going to be spent on lunches and and you know ancillary stuff In barcelona isn't going to be spent no one's going to go back and do mobile world congress lately later So that's just lost Uh and and it's it's going to have a big effect on technology the technology industry in general for sure Hey, folks, if you want to get all the tech headlines each day in about five minutes Be sure to subscribe to daily tech headlines.com and thanks to everyone who participates in our subreddit You can submit stories you can vote on other of your peers stories as well a daily tech news show dot reddit.com You can also join in the conversation in our discord going on right now Which you can join by linking to a patreon account at patreon.com Slash dtns. Let's check out the mailbag. Let's do that An anonymous federal drone that that was there there person or quadcopter. Yeah, hard to say They can talk That says I work at a federal agency and I just introduced teams. We were talking about microsoft teams in slack with rob dumbwood on friday's show Drone says i've been trying to get my colleagues to bring teams into their workflow Unfortunately, the key hurdle to this is my workplace's policy that we can't create our own teams And need to submit an it ticket in order to do so the integration into office 365 leads me to believe It would be great for managing vip travel keeping team members in the loop in general Right now this is being done poorly via email and whatsapp the rationale for the it ticket is that if individuals create teams willy nilly It'll burden record retention requirements However, a lot of that gets lost when we rely on whatsapp as well as the shared document viewing and editing capability I'm going to keep up my campaign and hope that when I get into a management position I'll be a little more technologically nimble than my current bosses It does sound like a little cya is going on which is look if we don't know you're arranging travel in whatsapp Then there's no requirement that we we we preserve that But if you open a teams channel, then we know it's there and we have to preserve that Um, I'd be curious if there's some sys admins out there who think like, you know, that's a reasonable concern Or if they're like what you just you just archive it, you know, yeah You have to pay a little more for your storage space, but it's not that much One way or another Also, we got a lot of reactions to the tesla story that we followed up on that tesla had done the right thing and restored The automatic driving so autopilot functions to the buyer of a used tesla Who was surprised to find that those functions had disappeared even though they're on the invoice james from ervine Points out that tens of thousands of used teslas have been sold over the past 10 years And all indications are that 99.9 of the time software purchases transferred to the new owner without issue I know it would have been nice if tesla had issued a statement about this But I think for them this was a non story one mistake was made and fixed and there is nothing worth talking about Obviously, many other people didn't see it that way Uh, remember this wasn't that transfer didn't happen It was that tesla went in with an audit and removed it because the names didn't match And james is saying yeah, but usually doesn't go wrong. Why are we focusing on the one time it did? Uh, and then tom mckague said in reference to the story on a car losing auto drive features If tesla really wanted to connect features to a car they could use the vin Not the purchaser name the vin never changes. That's the vehicle identification number But the owner might I feel that using the original owner's name instead of the vin shows how immature tesla is as a car Manufacturer it's either that or tesla intended to rip off the second owner by making them purchase the option again They just got caught when jelopnik ran the story tom. I would point you to james who's saying no, it's probably not that But I do like the suggestion that the vin is a more reliable way to track this stuff that there I wonder if there's you know Things that we're not seeing that would be a pitfall to that but it feels like oh when someone has bought it And it's attached to the vin If you then then your audit would always be like, oh that vin did pay for it. Okay, great, you know That's a good good insight tom. Thank you. Yeah. Yeah, it makes perfect sense Hey, shout out to patrons at our master and grand master levels including dr. Carmine m bailey mike mclaughlin and philipp lass And we have new patreon reward merchandise to celebrate six years of dts six years six Almost six and a third by the end of march. Anyway, uh, if you want to celebrate with us you can get a poster a sticker a mug or a t-shirt with the special dts six year logo on it Just become a patron or if you're already a patron just stay a patron Starting january 1st the clock started ticking. So if you stay a patron for three months You'll get one of these depending on what level you're at and you can check all that out at patreon.com slash dts slash merch Our email addresses feedback at daily tech news show dot com If you'd like to join us live, we'd love to have you we're live monday through friday 4 30 p.m. Eastern That's 21 30 utc and you can find out more at daily tech news show dot com slash live back tomorrow with scott johnson talk to you then This show is part of the frog pants network Get more at frog pants dot com I hope you have enjoyed this program


We are really excited that we're opening up a new urgent care center and it will be the first of its kind in the state of New Jersey, possibly in the nation, that will be a behavioral health urgent care center. We're going from the Radio Shack era to the Apple Store era and behavioral health finally. What we're trying to do is take the best parts of the clinical experience in the emergency room and providing it a more convenient and comfortable setting, a certain more outpatient phase. The urgent care center is going to treat a variety of different issues, initial evaluation on substance abuse and addiction, evaluation of psychiatric issues. The key is to have faster care, to have an efficient experience and one that provides great access to patients. You'll have whatever medical issues assessed and treated in a sort of typical setting right now in the emergency room, that process takes anywhere between 8 and 12 hours. Our hope is that this is going to take on the order of one to two hours in the urgent care, maybe even less. This is a great example of how we're transforming care for behavioral health patients.


Now, wait a minute, does it go like this? Oh, he's so neat. And this is one part I could talk in rock, Scotland if you're... Kenny Baker granting a request from Mary's mother. Say, Kenny, I told Phil what I thought about his work in the minstrel show last Sunday, and that goes for you two. Your blackface dialect was really great. Thanks, Jack. I didn't like it. Why, Phil Burt. And now, folks, as we announced last Sunday, tonight we are going to offer our version of that current 20th Century Fox picture, Girls' Dormitory. I will play the part of the hair director of the school, which was enacted by Herbert Marshall. Simone Simone's role will be played by Mary Mary, pronounced Mary Mary. And Don Wilson will play the part of the dormitory. Now, as you folks all know, Girls' Dormitory is a story about a school for girls only.  Is that okay with you, fellas?  I will, too, but I'll feel silly. Now, I think we need two or three more people. Say, Phil, would any of your boys in the orchestra be willing to help out? Well, certainly, Jack. You can have my arranger. You remember Ben Blue. Oh, yes, you introduced me to him a couple of weeks ago. Yeah, say Ben. Oh, Mr. Blue, would you like to help us out in our little play this evening? Well, it's a little bit out of my line, Mr. Benny, but if everybody else is willing, I guess I can do it, too. Now, you know, this is a schoolroom theme. You've been to school, haven't you? Yes, but I never liked school very much, so I quit when I was about 35. Maybe he doesn't have to change character. But you'll like it in this school.  Well, I don't mind as long as I don't have to change my girl. Fine. Now, let's see. Who else do we need? Come in. Hello. Hello. Am I talking to Jig Bani? Yes, sir. What can I do for you? Here's my car. Take a look and don't bend it. Your car. Let's see. Pat C. Flick. What's the C for? Salesman. And the last name is Flick. Yes, sir. Pronounce Goldberg Goldberg. Exactly. Now, Mr. Benny, I understand you're putting on tonight a show entitled Yes, sir, but what's that got to do with you? I sell door mats. Now, look here, Mr. Flick, I don't need any door mats. What I need are actors. Can you act? Can I hector, he's asking. I've been a hector since hector was a post. Well, look, I'll give you $5 if you go into our show. What do you say? Make it $7.50. No, no, no, $5.50. Take it or leave it. And don't leave it. Now, listen, I'll give you $5 in that final. Do you want it or not? Well, give me time to think it over. I'll take it. Now, remember, this is girls' dormitory, so I'll call you Patricia. Call us. I'll be glad to meet her. Well, I guess we're all set then, fellas, and we'll go into our sketch immediately after the next number. Playfail. $5.50. She's left.