All right sounds good. So good morning. Good afternoon. Good evening wherever you are today's agenda is Think we have two Three updates today, right? One two three. Yes So we have borough cello and training and education working group Did I see is Silas on There he is. Yeah, hi. So Any other agenda items other than the updates, okay, if not Todd you want to get Sure thing with the hackfest stuff. I was out the past two weeks Trace your Chris Anything we need to cover on that to catch up. I think it's just make sure folks get registered It sounds like there was some discussion. Maybe two weeks ago just on the Agenda planning in the GSC Paul, but right, but I didn't say I'm actually planning and Gotten in the way for a lot of people but Tracy for this call anything we should jam on otherwise we can connect up after and drive things forward No, really just a reminder that we're looking for agenda items Things that people will be able to hack on specifically to be added to the agenda cool, I Think that's it on that one Chris then and we can move into the updates. Okay. All right silence. You're up Hey, let me just get my butt to give you the Qt Q2 update again Q3, okay, so In terms of project health, I think a lot better than the last update I think probably on the last update. I was still mired in a fairly massive refactor. I hadn't been released for quite a while and That sort of thing since then burrow has been used to push out our as in Monax's agreements network T1 testnet for For our public legal agreements network It seems to be working Doing that has provided a lot of quite useful pressure on Particularly on operability on smaller things like how we generate config To bigger things like how we perform network boot Kubernetes Helm charts a load of stuff for running validator pools and it's also driven some thought about how we Model the separation between a human or organizational authority and actual validators and stuff around key provisioning So we now have two companies actively contributing to our development effort, which is nice One being TCS, which I had mentioned the previous update and another company Fintera who are building again a zoned public network in In a similar line to us and in fact their developers were making useful contributions I had no idea they were even working for the same company until we eventually had a call and joined up some of our efforts and thinking So the Grammy Factor is complete. So the entire stack including JavaScript libraries packaging tooling Is all in repo Bosma not there's still a GPL dependency there We may if we were to replace some of the aetherium ABI Stuff pull even more into burrow, but that's the direction of travel to make burrow increasingly Batteries included in that single repo and in fact rework the command line. So we have sub commands for creating Genesis specs configuring the chain very shortly for for running a key service And we'll keep adding stuff there so that that you can do a go get and then natively run a chain that being one of our focuses We also have nearly got full EVM compatibility We would have had it a few weeks ago, but I'm getting One of our sort of contributors and somebody who's kind of in the maintainer pipeline to implement these op codes And that's just incurred a bit more overhead, but we've got all the plumbing. So it's just Static calls that we're missing now. We've we've implemented Four or five op codes a couple of other EIPs. So we should be Running in the same compatibility level as public aetherium on not metropolis, whatever the next one was But the latest anyway, so Issues particularly driven by Us building out into this public network some stuff that we've kind of never worried that much about is coming to the fore So we need to have a flexible fee structure And when you start thinking this through there's a bunch of dimensions in terms of Where fees live like whether they're attached to a transaction or associated with a particular contract being called How they're set whether you have a market mechanism between validators And this is all in the background with tendermint changing and upgrading its interface all the time as it moves to 1.0. So What we need is an ability to charge for gas currently we meet a gas so that computation is term Terminates, but we don't actually convert any native token into gas which we probably need to have a Public network running Then there's also the idea of Taking a network fee Out of a percentage fee out of value that's being transferred So that works for some cases it kind of works for ours But the upshot is that we want a way to incentivize validators to run by making a fair cut of Transaction volumes and that depends on the domain as to what that means So I don't want to make too many assumptions about that but provide something that's kind of flexible to build on and we need it to governance I'm implementing currently some kind of primitive for governance that The first the first iteration of which is just a big pointy stick where a Single key is able to change validator set change permission change native token distribution change consensus parameters The idea would be then to wrap that up behind an autonomous probably a model as a contract agent that can take votes from validators or votes from a selected quorum of keys or And can manage like unbonding periods so that you deal with certain nothing at stake problems It's a huge Complex issue, but I'm trying to build like the simplest base in borough that that you could implement various governance methods on top of and we're also working with a Academic group that's doing some stuff and voting projects which may help us out there But changing the validator set is like the thing that we really need and that should be in this this sprint I'm in a two week sprint right now We also need the ability to do some kind of escrow between between chains so Is it quilt that is the hyper ledger project that is doing something with Intelligio, we're kind of in the model of Cosmos, but that doesn't really exist yet I mean that they're launching but the idea of having cross-validation and the ability to escalate a particular transaction type into blockchain Transaction that's the kind of model we're working in But we're gonna need to be able to fake that and essentially do a Distributed lock. So you stake something on Ethereum our validators are able to go and Check the state of that contract then we will mint that token on our side Token and or data, but it'd be useful to get some feedback from Other projects about how they're doing this. I the plan would be to run it on a quite a slow basis It like, you know, maybe once a week or day just so it can be monitored But I'd like to get some kind of support for doing stuff like that in borough And don't really have a plan Okay, releasing. So yes, we finally made a release with like 161 commits or something the next release will be much sooner than that So that's zero Zero 18 zero it was released on the night of May. There's a change log linked in the In the wiki page. There's there's a ton of stuff there and generally I'm much happier with the The basis that we've got to build on in terms of code and there's some features in there as well including a tendermint upgrade although that already needs to be done again It's been a bit so fast So overall the chat channels are getting pretty busy particularly in borough contributors Which is really generating for me some useful discussions, which is great The borough mailing list is quiet because I've kind of totally neglected it But I was thinking I could send a mail in to the ether there with a Package of the updates including this Do this probably after the call So current plans are the big ticket items that we're working on kind of mostly within Monax in this sprint is we've done a big Cleanup of Monax keys, which is this was this satellite project. It wasn't boss mama. We're pulling it in to borrow and We're maintaining the same interface to implement HSMs and things like that behind but we're cleaning up the crypto updating the libraries We're moving some intermediate layers from like go crypto, which is this tendermint library and trying to go straight to source So we're using BTC suite for the secp keys and we're using the standard golang ed25519 stuff and generally just removing a lot of cruft And again, this is in the direction of the sort of self-hosted borough So you had to install something from another repo really to use borough Or you could implement Monax keys yourself, but of course no one did. So it's now a sub-command The Monax key stuff is and we're gonna have some better options for The model I'd like to move towards that is when a validator comes up within a validator pool It generates its own keys. They never leave the HSM or the machine And then we have some way of getting that public key bonded onto the chain rather than what we're doing at the moment which is generating all the keys in a big bang and provisioning them around from From a CI system or even from a developer's laptop I've got another note on that a bit later So yeah implemented GovTX that's the mechanism I was discussing there under the issue So that's I guess governance is also an issue But this is the underlying layer that we need to change validators I've got an idea about doing and another thing that's going to be pretty nice particularly for us We have a an object relational with a solidity relational mapping Hack really that is called sequel solve, but it does work and it gives us a queryable view on Solidity contracts It will be massively simplified by having an event system that isn't Based on subscribing and making sure that your connection doesn't drop and that you're around for time So we'll have an event firehose where you can say give me all the events between block n and n plus m And it will give you all of those events possibly with some filter that you can get and you can request them again Whenever you like so a consumer can just remember its offset and it can backfill A load of events I'm just wondering if I should be on the TSE room Yeah, that's fine So, uh, yeah, and that's what's going to be able to drive integrations things like Kafka and that's a big thing for us because we want to be able to drive Say like legal back office systems and things like that, but but generally um, and we'll build the Kafka adapter will probably be a separate quite small client to this Oh, and all of these things are moving on to gRPC as well So the the keys is the first thing to have a gRPC interface and we'll be creating Existing methods on on gRPC Rather than some of the hand rolled json rpc stuff Um, major theme for burrow. Yeah, it's it's operability ability. So network formation stuff The idea of like a hierarchical identity for validator pools. So the idea that uh So say we're running a pool of like seven validators if we have a a key that is like the master key or the validator pool key um, and that Is will be the key that can bond any Any server that comes up into that pool? um So there's a few reasons why this layer of indirection is quite useful Uh, certainly in tendermen. Um, and I'm thinking we should capture it explicitly in our account model somehow. Um Yeah, improve configuration kubernetes helm charts, which are now as part of the the helm library And then we need to look at state snapshotting to catch up with chains. Um, should be fairly straightforward in terms of getting a level dv Checkpoint, uh maintain a diversity. So we're still pretty monax heavy. Um But that uh, we've we've added um My new colleague shawn young to the maintainer list. He's working pretty actively on burrow Um, we've got uh me kasey and tyler from monax. We've also got a pretty good pipeline. I mean For us anyway, uh of our future maintainers So there's a couple of guys from fenterra guy called amid uh puller pullerzade and mostafa sedge cat Who I've already made useful contributions I'd expect by the next update that they will be fully maintainers, but it's still quite new relationship We've also got shawn from tcs. Um He's a newer developer and needs a little bit more practice before I'd be ready to make him a maintainer, but but On the horizon we would at least have a Better bus factor on companies um Contributive diversity. Yeah, we've added three new contributors one uh, like possibly More than that for for some documentation. Um, there's a couple of people doing like phd projects and things on on burrow Who have started to write some docs haven't been merged in We've also got a piece of tooling called snack. Um written by amid actually Which is not Obviously on the hyper ledger organization, but it is explicitly for burrow. So that's an entire kind of truffle like thing. Um Yeah, and and and shawn black black as I said, um, it It meant meant that we had to go a bit slower on some of the evm up goes But he's he's given us some really good work on getting up to Most recent evm compatibility um So then yeah under additional information here, I just Made one remark. I don't know whether it's worth discussing now. Um, but So burrow is known as the hyper ledger project with an evm but uh after A consensus and more generally we're working very closely with tendermint and cosmos now and It sort of feels like particularly with some of our plans that are away from the evm that we could Sort of come to be the project for building permission Public chains on tendermint slash cosmos or even the hyper ledger app for tendermint or something like that. So burrow will increasingly have some support for, uh, this Generating like fee gas schemes. Um to run your your your public, uh, your public zone In a in a doesn't explicitly have to be tendermint, but it's in that model of zone communication There are some other consensus engines that have a similar interface Also for running business process as in bpmn. That's what the agreements network does. Um, And we're going to have some support in our s natives for Doing some of the execution there Yeah, and and then this business around escrow we want that to develop into a way of sending, um arbitrary messages using this ibc Into blockchain transactions Um, so I don't know what bearing that has on what input the tcs would like to have on that whether You feel that this would belong well, I mean We would we could always do this in a fork, but like just how to imagine the development of burrow in this direction and particularly with this kind of uh tendermint emphasis, um Yeah, anyway, I just thought it's worth remarking, but um, that's it Tell them to come on down Um, I'm enjoying yeah, exactly. Well, they're not to join they just have to set up job. Um A couple of points, uh on um on your update, um, which I Appreciate, um so in terms of uh, you mentioned the need to uh be able to Charge for gas and I have a similar requirement for what we're doing with the burrow evm plug-in for for fabric So we'd love to Collaborate with you on that Yeah, um, and then yeah as for the um, you know escrow or you know interoperability with other chains Yeah, we should We should we should talk about that too I suspect our two guys are also interested, but I like Kelly to speak for them Yeah, so I mean that that would that would that would be good. I think that the the gas charging is something that Uh could could fairly easily be added as a question of what artifact we want for the schedule Um, currently we collect a fee that is set in the transaction and the fee can be Set to to whatever you like uh newer versions of tendermen are allowing us the ability to push through on our Transaction check. So that's the when it enters the mempool Um to push back what what fee is offered and then they'll use some approximate algorithm to try and pack the Get pack into well each proposal will try and get the maximum total fee packed into a block So, uh, that that'll be the tenement integration piece for us. But then um, there's a there's a few there's a few axes on which you could try and do the fee stuff. Um You can have a competition there Although it doesn't allow per validated competition. There's also the the possibility that I kind of prefer is Taking a percentage of any value that's transferred um, because mostly so in our particular use case, we kind of think of Computation has been commoditized like almost negligible cost particularly for um, uh Operations are more bookkeeping when they're compared to the operations are actually for example listing an agreement Now, I know that doesn't work for everyone and I've been speaking to fintera people and it doesn't work for them. Um, so Yeah, it doesn't get a use case that that i'm thinking of is actually more where the gas is used just as a rate limiter Not necessarily as a fee or some sort of incentive for running validators and so forth Although it could be again, but you know at least You know the initial set of requirements that I have is more for rate limiting In other words, you know, you can do 10 000 transactions a day You know or something like that, right? And if you need to do more, you know, you need to You need to ask permission that kind of thing So, yeah, actually that that's something I would because I mean Volumes of transactions are always going to be relatively limited on On a pbft style system well, yeah and one One thing I quite like to do is I mean I slightly worry about the the nature of validated voting power, which is the Essentially what we would model as a token, but we would transfer into the tenement voting power as a mechanism to extract rent but another way for them to extract rent using this other than the fees is To be able to have a certain quota So we could quite easily base that on the relative voting power of a validator Which also has its own rpc And it gets the right to some number of slots pushing transactions in Which might be a kind of interesting way for Also for operators to specialize whole voting power To operate a node and then auction off their their transaction quota. So, yeah, I'm kind of interested in thinking about that stuff, too Yeah, I think it sort of needs a bit of bit of modeling away from the code. I think Anyway, so just uh Oh, sorry, I was going to ask for the for the work that's being done to tenement. Is that um to make that Uh in burrow in particular to make it a sort of fully public permissionless Uh network or is it still going to have sort of permissions on? You know, who can who can send transactions and and some of this rate limiting? Uh, I guess just yeah have some questions on on the public capabilities of of burrow So it will remain uh commissioned um But it will also be public. Um And For validators we will be finding a way to distribute validator token and we'll have a minimum bond. So in order to be a validator Your Well, they're also going to be starting off like what we're doing in the in the t-series We've got some more companies on board. So we know who they are as well So so that's kind of invite only for participants currently certainly for the test net. We're not restricting um participants But no one is able to create contracts. So all of our contracts are like autonomous factories that can create other stuff So we've actually got some contract level uh Kind of permissioning but in terms of if you if you're a punter who shows up and wants to formulate an agreement on for us then then that would be open and that would be the idea Running burrow in that mode whether at some point we would need um to Uh Start limiting a transaction coming in that that may be the case when when we have this model where there's Uh where where burrow network can start as a tendermint zone um Then I think there's potentially a way in which that becomes sort of permissionless in that you don't need permission to start your own zone um But but otherwise we would be sticking with the permissions and as I say this we don't actually So some people are using burrow to be a Drop-in ethereum replacement. So they want They want every the global permissions to have the create permission. We don't actually give anyone Any participant the create permission and we actually We need the that's why we need the governance stuff when we need to do an up a concept upgrade It's only going to be a governance agent that can do that Um Okay, got it. That's that's useful. No the one last question I had just thinking about um, sort of how burrow's positioned is Uh, I know there was recently an announcement of the enterprise ethereum Uh spec and was curious if that is if uh You guys are involved in that at all and if that's a goal with burrow to be compliant with that spec Um, it's a power point, but I I hadn't um, uh I hadn't noticed that um, I'm not against taking a look at it. But frankly, uh, I was pissed off the last time I engaged with uh enterprise ethereum And I'm not sure what state they're in leaving their bootstraps themselves. Um, but uh, yeah, I take a look. I don't know What I was arguing for was For ethereum was an effort to unbundle Um into manageable pieces, you know, like a decent ethereum spec would be really useful Like the yellow paper is not a decent spec. Um a decent spec on um, how gas scheduling should work on Vitalics kind of ideas around unloading state that hasn't been rented out. Like that's potentially interesting. So so I'd yeah I I will take a look. Um, but yeah, I don't know without without looking at it and um, also just like Getting my finger back on whether they're a functional organization Okay, perfect. Just wanted to check. Thank you Could you expand just a little bit? You made a you made a mention in passing sylas about maybe borough becomes the I think you put it like the the hyper ledger application for endermint Um, may have misquoted you there, but can you say a little bit more about that? Sorry, just finding nothing to unmute. Yeah, so I'm not quite sure how to phrase this but um I guess I feel it's like it's certainly it It's a an area that we're doing a lot of work in to support our use case Certainly some of this I mean It will is going in is going into borough and I suppose part the question is Maybe how much of this belongs fully in borough or as an extension? but If you look at so what what so tendermint has this quite, uh forceful Uh interface where it kind of it kind of owns the p2p and it owns all that stuff and I think that that's that's been an issue for You guys like sort of all fabric integrating which kind of want to have a little bit more control over your Consensus network and and there may be some scope there for for breaking it up But particularly with their the stuff they're building in their sdk Actually obeying roughly speaking the abci interface allows you to go and play with the broader Tendermint network now the current art on this is so they have their sdk and they have this base coin app Which provides some useful stuff, but is very much focused on things like decentralized currency exchange So no one's doing stuff like we are which so at the core of the legal agreement stuff is is this business process modeling on a chain On on the one hand and then there's a load of like operational stuff Like so the way that we have provide the private validator over an interface that could be plugged into hsm The way that we're handling our state that there's a bunch of things that And of course the evm itself and also thinking potentially about other execution um, but there's a way in which we're building a lot of stuff that Probably provides something useful if you wanted to Launch a public, you know a public or semi public zone that could connect to cosmos And So I know sort of brought a tendermint ecosystem so What am I asking? I suppose Do we think this belongs in burrow like what how How are projects evolution guided? Um, would it be useful? How would it link to other? Other projects. Um, is this something that could end up being a library? I mean, so one thing that I didn't want to end up doing I think as I've said before is to try and have Plugable consensus. Um Totally pluggable execution engines ideally not break out of a single process because that sort seems to be the niche um I'm going on to a more general purpose execution against tendermint. There's a slight risk there, but um But yeah We are a tendermint app in the sense of we implement the abci application interface That's when I say app. Um, and we have a lot of other stuff that relates to building with permissions building with Gas and fee incentives particularly as we develop that. Um, and that seems like it's it's useful if anyone wants to wants to play with tendermint Which obviously has its um, its own Kind of unique selling points on the consensus mechanism there particularly once it can be show added into zones Okay, thanks. Thanks for the update in general silence So thanks Alice. This was a great update. Um, I think we should move on because we have two more So I think up next was where did my window go? Sorry Is it Uh chelo update chelo so bawa. I think I saw you on Yeah, and uh the maintainer head tall will do the update Okay Oh, yeah. Oh, okay. So this is the head tall um No, I will introduce to you um progress over the second quarter for the chelo and And the plans for the next quarter So, um currently we have released version zero point eight And the and the next release version will be zero point nine so in in current version um We have these features user user can deploy fabric networks in docker and docker swarm Um and the user can can also apply the fabric fabric network in In the user dashboard then they can see the status of the fabric network and and also can upload Deploy and call and query the smart contract in the user dashboard And in the in in the last quarter The chelo chelo chelo community Are being very active um And we keep weekly weekly regular meeting Yeah, and and currently also we also have three maintainer who Are working on the project actively um And now we we have provided we have provided some tutorial video for for chelo startup And in the future we will record more related tutorial video um The constant the constant plan for the channel for the chelo, uh, mainly are And the mainly The constant plan for the chelo mainly are the Refactor the code for operator ui and the both ui and the background service of the user dashboard List change in mainly for code specification And refine overall architect design for the user dashboard and operation of reader dashboard so This will let the community developer understand the code struct easily and develop development faster And the other the The the biggest feature in the current plan is to support Kubernetes agent um Based on this feature We'll provide provide the users with more with more ways to deploy Deploy fabric networks And and the other feature is to integrate composer with chelo um And we also have some improving Improve improvement uh included uh dynamic dynamic Certificate generation and management for the For the fabric network um in the current the certificate method is static and static fixed method Is it is it very easily? um and um operator operator can import and operator can import Exited the fabric network into the pool of the fabric network So this we will give more ways to Create fabric network in chelo um In the user dashboard User will will can watch the logs or all node in fabric network and Added to the smart contract online easily. So let's let's mix user um To debug the smart contract easily um and We we will ensure the release version zero the poison line in the end or this quarter yeah, and I think this is all the updates for the Chelo product that's in in this quarter so any Any questions? Any questions from the others? Great Okay, uh, thank you. So I think next up is tracy Hey chris, uh, actually i'm gonna have uh kelly cooper. I do this update Kelly was elected prior to our decision to have the tsc elect new chairs for the Education working group. Uh, so she will be running the working groups and the updates for the training education work group kelly great. Thanks tracy the training at education work group is A collaborative group of people who are keen on hyper ledger We are having kind of a transition between intent and action it's almost a little bit of stage fright and we have Try to kind of setting up a process and setting up sprints and then we took a look at a couple of examples We have some great opportunities for example The edX course for hyper ledger is now up to 100 000 users And so some of our graduate students especially can benefit By contributing to the next course or the next version of the course and currently can contribute to the discussion forums within the edX course however We do more talking than we do developing And so we're trying a couple of new Ways around that. Uh, one is one of our members is working with tracy to Kind of set up the style guide for the way that images might look Um, we have a lot of conversations about target audience because there are many and about kind of breath versus depth At this point what i'm working on is utilizing documentation and putting together Some potential templates for how it is that people can help build learning materials And so I would say that the group is interesting and excited We have as many learners as we have people that are ready to prepare learning materials We can utilize them for testing The learning materials however In our next update. I hope that we will have more actual materials to present than we have enthusiasm to discuss That's it Tracey, did you want to add anything? No, I think I think that's pretty much the case right and um, You know, I think the the thing maybe is to Ask the tsc and and people have been involved in new working groups kind of how to get past that You know initial initial phase of of the working group right where it's Seems like there's there's not a lot of Output but more just you know passion for for trying to do something but not really sure how to get started Um, you know, I know We've seen similar sorts of updates for the first time with different working groups and So like is there any sort of words of wisdom that we we can offer as the tsc to the training and education working group? And I'll add to that also that as tsc If we have particular areas for example with cello or burrow where you can really use and request some materials and More of that targeted focus might help us to get a few people to Be less nervous and more productive so I guess um Let me see if I can if I can frame this correctly. So you have an awful lot of interests but Is it that those that are interested don't know how to Contribute or they don't have the expertise or help me understand I think more of the expertise and so at first I thought that they might not know how to contribute and so what we tried was Existing training inventories. I set up database for ideas that people saw on the internet whether that be through medium or through other materials to collect that And we had no no response or two responses. Then we set up a kind of an idea list of things that people would like to contribute to and then that looked like it was going to go somewhere and we asked for People to self identify if they would be contributors or learners and for most part they were learners And then we set up I mocked up three courses One on blockchain technologies another on iot technologies just to kind of find out if people were interested in kind of business use cases and No one responded to that then we set up a style guide for what it is that distance education looks like with today's Understanding how we could differentiate ourselves from mooks with good materials Everyone was enthusiastic and there's no response. So we've got about a dozen different possibilities set up on google docs And I do see when I'm in there, maybe two or three people looking at it We've got a couple of people who like to talk and talk You know, it could be this it could be this and so I don't What we're trying to do is to corral a little bit and just say let's pick a couple of topics But for example, we had the opportunity to look at the sawtooth documentation that will go into Ed x and everyone was enthusiastic, but still did not really have any Um kind of Contribution from a technical nature. And so one thing that we've thought about can I can I can I make a suggestion because I think I see where this is going and I think rather than maybe necessarily sourcing new Material maybe the thing to because there is an awful lot of interest people would want to learn they're hungry But maybe the thing to do for this working group would be to work with the various projects to help them understand where There's a need to improve whether it's their documentation or their inventory of samples or what have you That this working group can help facilitate That kind of interaction as I think a lot of times people are afraid to say hey, you know Or or or the questions are sort of gets lost in whether it's in chat or You know in in in hyperspace or whatever You know, I really wish there was You know something that told me how to build a Transaction family or whatever Or you know, how do I do a chain code that kind of thing? I mean It just might be worthwhile just sort of Working with the the people that are showing up and saying hey, let's go through what's there and let's build a a gap analysis of what could be added to improve it and then working with the project teams to figure out how they can Help to span that gap because I think the expertise is always going to be a shortage and it's likely to You know fall squarely with those that are developing the various tools and platforms but I don't know what others might think Kelly or Dan or One other good thing and then I'll pause and that is what we did in our last meeting was We offered let's take a look at the existing tutorials and start to go through those and to identify areas where perhaps you got stuck And additional information might be interesting or maybe the vocabulary was that it needs to be expanded on to where You can link from the existing tutorials to an image or to more detail that would help to For the reader to kind of understand what that was. I mean that would be huge. I think that would be huge So we were calling that a visual dictionary and we've been trying to get that going for two or three meetings as well so I don't I don't discredit at all the enthusiasm of the group. We just need somehow it's like We're not quite at the right combination, but I think it's going to be a great group. And so we are trying to at this point work with the existing materials Because I just I'll I put this in the tsc chat But I I agree with you 100 right there are actual comments coming out in these working groups of Things that they wish were different or problems that they're seeing in the existing documentation and that sort of thing. So You know, maybe it's it would be worthwhile for us to create a thread on the training and education working group mailing list that really just ask people for Hey provide feedback on on like where you're having trouble with getting started or The existing material that you're finding That's not working for you that sort of thing. Yeah Like I said, it would be huge to get that kind of feedback and to have it You know focused, you know through the lens of the working group, you know, sort of pulling this together and then having you know Some coherent ideas about what we what we might do and how we wouldn't might how we might prioritize and so forth. So And the other nice thing about that is someone is contributing to something that's already in process in case starting something Is part of the wrinkle Right and and sometimes it is just getting started and people start by you know just Fixing typos or fixing grammar and and then they start to learn it a little bit better and feel a little bit more comfortable they get A little bit more involved and I think that you know You know again You know, we we you know, I think we're better when we're collaborating together and and driving you know You know driving more Again, I think I think a lot of times people feel Oh, you know, I can't You know I'm not worthy or I don't know what you know about you know engaging with a project and feeling like they're a part of it That's it's a large part of the hurdle of getting started And and so this this working group I think could be very effective that you know getting People a little bit more engaged in the various projects and helping in metaways, right? You know, they may have meta Contributes, they may not be experts But maybe by virtue of the fact that they're consumers Getting together and they could say yeah, it would be really great if we had more samples or if we had Better examples or if we had tutorials as opposed to just a bunch of code That we're supposed to sort through So anyway So on a specific case, so this is Silas from burrow. Um, there's somebody who's doing their thesis For like bachelor's or masters or something called valve valve wear on the burrow chat and he's Offered to write up his experiences and like he's had various issues Because out of date docs and stuff, but he seems to know what he's doing And he's someone who's offered to write this up and we said oh that'd be great for the project Could I put him in touch with someone because I think all he might need is a bit of like guidance slash hassling which I'm Want to forget to do Would that be part of this sort of an effort? Yes Okay, so she like she like um, shall I ping you on chat and get him on there? Yeah, okay cool The other thing is is that um, we're being really, um, encouraging And I think that everyone in the group sees this as an opportunity so it could be That placing people in additional collaborative environments would be a great fit So the feedback is much appreciated Any other comments questions suggestions? For Kelly, okay. Thank you very much All right I'll give people eight minutes back unless there's anything else All right, talk to you all next week


Yes, the Guardians of the Galaxy. This is the original Guardians of the Galaxy. This book right here, The Astonishing Tales, number 29, published by Marvel Comics in 1975. This is actually not their first appearance. This is a reprint of their first appearance, which happened in the Marvel Superheroes series, I believe, with art by Gene Cullen. This big guy here, his name is Charlie Seven. He's from Jupiter. Each one of these guys is the last survivor of a human colony in the year 3007. Charlie Seven is from Jupiter. That's why he's so huge. His his race was genetically engineered to survive the gravity of Jupiter. Never mind that you can't actually walk on Jupiter. This guy is Martin X. He genetically engineered human from the planet Mercury, I believe, and then, oh look, the book's coming apart. But these guys are struggling to survive against the occupation by the alien Badune. And this is Vance Astro, the guy here in the purple jumpsuit. A 20th century astronaut who somehow survived into the three thousands. And then there's this guy, the blue guy with the fin head and the arrows. He is the only character from the original Guardians of the Galaxy that has made it into the movies. His name is Yondu. If you're a fan of the movie, you will recognize that name. He controls his arrows by whistling. And look, there's this ridiculous, they're singing the song Earth Shall Overcome Sunday. Guys, but there you have it. This is the actual Guardians of the Galaxy. Please remember to press that like button. It helps my videos get seen and then subscribe so you can come back next time. I do science fiction book TV and movie reviews all the time and please consider becoming a patron. There's a link in the description below.


The series RLC circuit we took to be this and I wrote the differential equation with the capacitor Vc as the desired variable and this Vs steps from 0 to VP but in general it could be anything okay. We are now looking at a constant input and a parallel RLC we could have this. I believe this is the example I took last week as well. Let me just check and again I will write the differential equation in terms of Vc as the variable okay. So we will have in the first case this is the differential equation we get okay. Mainly we are now interested in the left hand side of this. The right hand side when equated to 0 you get the homogeneous differential equation and the natural response can be obtained from the homogeneous differential equation and in this case the coefficients will come out to be slightly different in the parallel RLC case okay. So this is what we end up getting. Again the right hand side is not so important. The left hand side it has the same structure as this one. These two look similar to each other okay. Now a general differential equation of the second order will be of the form. I am assuming the homogeneous case okay that is the right hand side is 0. Now we know that a differential equation of this type has solutions of the form exponential Pt. Now we know this because the time derivative of exponential Pt is also exponential Pt times some number okay. So if you go on differentiating you will go on getting exponential Pt and it is quite easy to see that but could potentially satisfy this equation for the right value of P. So how do you find the right value of P? We substitute exponential Pt in the differential equation. All the exponential Pt's will get cancelled out and we will be left with a polynomial in P which is known as the characteristic equation of this differential equation okay. So what we get if we do that here if I substitute exponential Pt in this we will get a2 P square plus a1 times P plus 1 equals 0 okay. So all we have to do is the second derivative is replaced by P square first derivative by P and this Vc itself by 1 okay. So clearly this will have two solutions there will be two possible values of P that will satisfy this and they are given by P1 P2 are given by the solutions to this quadratic equation which is minus a1 by 2 plus minus this okay a1 square square root of a1 square minus 4 times a2 divided by 2. This comes from the very familiar solution to the quadratic equation. So now again there are three possibilities to this the term under the square root could be positive 0 or negative depending on that we will have two real roots complex conjugate roots or two identical real roots okay. So a1 square greater than 4 a2 or in other words square root a2 by 2 a1 less than 1 or let me put it in another way let me copy this over. So what I have done is to write the differential equation with some general coefficients a1 and a2 so that it is not tied to some specific circuit okay. Previously we got these coefficients in terms of LC and R we will do that when we go to the specific circuit but this will tell you that it is not specific to RLC circuit it will be the case for any circuit that has a second order differential equation describing it okay. We will connect it to the actual coefficients in different circuits okay. So now in this case we have three kinds of solutions one is when a1 square is more than 4 a2 this can also be written as square root of a2 by a1 less than half or equivalently a1 by 2 square root of a2 greater than 1 okay. So these are all equivalent statements I hope that is clear this inequality says exactly the same thing as this which says exactly the same thing as that okay. So now in this case we will have two distinct real roots okay that is this term under the square root is positive that means that the square root is a real number that means that both these p1 and p2 will be real numbers which will be different from each other because one comes from a plus sign other comes from a minus sign. Now what I would like the participants to do is to tell me whether both p1 and p2 will be negative or one will be positive and one will be negative or will both be positive okay. Please look at these numbers and what I will tell you is a1 a2 are both positive okay this we know for a series RLC case a1 was RC and a2 was LC because these are real component values which are positive these numbers will be positive okay. So please tell me if both of these will be positive both will be negative or one positive and one negative and for this particular case okay what do you think okay there is a correction to what I wrote here this is the roots are I should have a2 in the denominator okay thanks for providing the correction now of course this does not change this inequality in anyway so please let me know if the roots will be both positive both negative or one positive and one negative so it should be clear that both the roots will be negative because a1 and a2 are both positive so this number is positive sorry this number is negative and this the square root of this if you take plus the square root of this you can see that the second one will be positive but smaller than this negative number so the overall result is negative and when you have both minus signs naturally the whole thing will be negative also okay. So the answer is that p1 and p2 will both be negative in this if a1 and a2 are positive okay so we will have two distinct real roots and both negative what does it mean for these roots to be negative it means that exponential pt if p is negative this means that this response will die out with time okay exponential pt it decays with time okay so that is the implication of p1 and p2 being negative both are negative which means that eventually the natural response will go to 0 okay this was the case with the RC circuit and this is also the case with this one the RLC circuit okay I hope it is clear why both the roots are negative okay when both terms are negative of course it is obvious when the first term is negative and we take the plus sign here this entire term is smaller than this so the overall result is still negative okay these are all things that we evaluated last time we did it specifically with values of LC and R now I will do it generally with a2 and a1 and show how the two cases of series and parallel RLC are different from each other okay and this case when a1 a1 square equals 4 a2 what this does is to make the term under the square root 0 so both p1 and p2 will be equal to minus a1 divided by 2 times a2 okay and of course that will be negative because we have minus a1 by 2 a2 okay and finally when a1 square is less than 4 a2 in other words square root a2 by a1 is greater than 1 greater than half or a1 by 2 square root a2 is less than 1 we have the term under the square root is negative so the square root itself will be an imaginary number and we will have the two roots to be minus a1 by 2 a2 plus j square root 4 a2 minus a1 square I will reverse the sign inside the square root by 2 a2 and the other one will be minus a1 by 2 a2 minus j square root 4 a2 minus a1 square by 2 a2 okay so more than the exact values of this what you have to notice is we have plus j times some number here minus j times the same number here the real parts of the two are the same the imaginary parts of opposite signs so what we have are a complex conjugate pair of roots so we have three different cases and there is a reason I wrote the same condition in three different ways this is in terms of coefficients here I have defined some parameter less than half and here I have defined some other parameter greater than 1 okay the reason to do that is that these parameters this one and this one are some standard parameters that are very widely used okay. So if you write the differential equation like this let me copy over that if this is the differential equation a2 being the coefficient of the second derivative a1 the first derivative and 1 is the coefficient of Vc this is important then the characteristic equation of this of this form okay you have to normalize this to 1 that is important okay that is the way we have done it then this parameter square root a2 by a1 is known as the quality factor q okay it is usually denoted by q the quality factor and square root a1 by 2 square root a2 is known as xi the damping factor okay so these are constants that are used quite commonly to describe a second order system okay so square root of a2 by a1 is known as the quality factor and a1 by 2 square root of a2 is known as the damping factor okay so clearly you can write the three conditions these conditions in terms of either the quality factor or the damping factor okay so this same thing is written as q less than half or xi greater than 1 okay and here the conditions will be opposite okay so now we have the series and parallel RLC circuits okay let me copy these things over so please tell me what is the quality factor of the series RLC circuit in terms of the component values in terms of R, L and C okay please give me the expression for the quality factor based on the definition I just gave you the definition is here this is the definition corresponding to this differential equation so what I would like is the quality factor for the series RLC circuit okay what is the expression for the quality factor so this is a2 this is a1 and the coefficient of vc is 1 like I said if it is not 1 you have to normalize that by dividing it by dividing the whole thing by that term okay so the quality factor of the series RLC circuit which is square root a2 by a1 is given by 1 by R square root L by C and the damping factor xi is given by R by 2 square root C by L okay I think a couple of you were able to answer this quite easily it is just a substitution of terms okay so now what I would like is the quality factor of the parallel RLC what is the quality factor of the parallel RLC circuit yeah I got a couple of answers to this as well and it turns out the formula is the same as before it is square root of a2 divided by a1 and that would be R square root C by L okay the damping factor xi would be 2 by R square root L by C and also by the way it is pretty obvious that from these relationships from these two that the damping factor xi is 1 by 2 times the quality factor and vice versa okay so the exact damping or quality factor will depend on these coefficients in both these cases there are L R and C but you see that the expression for quality factor in fact is the reciprocal of one another in the two circuits okay so that is why I defined the quality factor and the damping factor based on the coefficients a2 a1 and 1 this term has to be normalized to 1 then the second order term is a2 first order term is a1 then the quality factor is square root a2 divided by a1 okay now depending on the circuit that you have it may not even have R L and C okay it can have two capacitors or two inductors and so on you can find the quality factor or the damping factor okay so especially what I want to emphasize is that the quality factor expression is different for a series RLC circuit and a parallel RLC circuit okay so do not try to learn any one of these formulas by heart depending on whether it is parallel or series the damping factor will be different okay now one sanity check you can use is the following a series RLC circuit looks like this and I have nulled the source okay and quality factor is given by 1 over R square root L by C okay now if R tends to 0 the quality factor tends to infinity okay and if all tends to 0 in the circuit what we will have is only L and C in parallel with each other okay now if I take a parallel RLC circuit okay let me close this and open it again there is some problem okay if I consider a parallel RLC circuit which is nulled quality factor of this is R square root C by L and if R tends to infinity Q tends to infinity okay and in the circuit we will have only L and C in parallel with each other so what I want to emphasize here is that when quality factor tends to infinity you will have only L and C in a loop okay so the quality factor can tend to infinity if R is 0 or R is infinity if R is 0 in a series RLC circuit then you will have a single loop of L and C and the quality factor of that is infinity if you have R equals infinity in a parallel RLC circuit you will have a single loop of L and C and the quality factor of that is infinity okay so do another sanity check that you can use at the circuit level when the quality factor is infinity that is let us say you get a certain expression for quality factor and you adjust the resistance value so that quality factor goes off to infinity then in the circuit what should be happening is that it should be left with a single L and single C in a loop okay it should be a lossless loop and Q equal to infinity means R equals 0 in the series case and R equals infinity in the parallel case okay so mainly I am emphasizing this over and over because the formulas for quality factor for series and parallel RLC circuits are opposite of each other but there is nothing contradictory or confusing there should be nothing confusing about this it is just that when the quality factor tends to infinity you should be left with pure L and C in a loop that happens when the parallel RLCs resistance R is infinity or the series RLCs resistance R is 0 okay I hope that part is clear now let us take the case of quality factor less than half which means the damping factor more than 1 basically means that A1 square is more than 4A2 okay so in this case P1 and P2 will both be real and negative now the natural response will be of the form A1 exponential minus P1 t plus A2 exponential minus P2 t okay and the constants A1 and A2 you can adjust using initial conditions now qualitatively if you look at these curves exponential minus P1 t might be like this okay and exponential minus P2 t might be like that when I plot them versus time so the combination A1 exponential minus P1 t plus A2 exponential minus P2 t okay it could be of depending on the initial condition I will assume it starts from there it could be of some form like that okay it will be just a combination of exponentials now let me take the other case when the quality factor exactly equals half or damping factor equals 1 and A1 square equals 4A2 in this case it turns out that P1 and P2 are real and identical the natural response it turns out because we have only a single value of P1 that is P1 and P2 are real and identical the natural response it turns out consists of this form A1 plus A2 t times exponential minus P1 t okay so this means P2 equals P1 so if you say exponential P1 t and exponential P2 t they will be the same as each other so the actual natural response will have A1 plus A2 times t times exponential P1 exponential minus sorry not minus P1 exponential P1 t okay I think previously also I perhaps wrote this wrongly it is exponential P1 t and exponential P2 t okay not minus because that minus sign is in the value of P1 itself okay and in this case when the damping factor is 1 or the quality factor is half the natural response will be A1 plus A2 t times exponential P1 t okay finally when the damping factor is less than 1 or A1 square is less than 4A2 P1 and P2 will be a complex conjugate pair okay so what does that mean the natural response will be of the form first of all P1 and P2 I will write as some real part PR plus or minus J times an imaginary part PI okay so the natural response will be of the form A1 exponential P1 t plus A2 exponential P2 t which can be written as A1 exponential PR t exponential J PI t and A2 exponential PR t exponential minus J PI t so this part is real and these parts are complex okay so these are complex parts and I will take out the real part this is what the natural response looks like okay now the natural response itself is a real number that is we are talking about a voltage here for instance in case of an RLC circuit the natural response of the voltage we see so what I would like from you is the conditions on these coefficients A1 and A2 so that the natural response is real okay what are the conditions on A1 and A2 so that the natural response is real what are the conditions on A1 and A2 so that the natural response is real it turns out that because these two are complex conjugates of each other if A1 and A2 are also complex conjugates of each other some will be a real number okay so this condition is A2 being complex conjugate of A1 okay so in that case the entire expression is real okay now the whole thing looks very complicated but mainly what I want to point out is that A2 is the when A2 is the complex conjugate of A1 and you know that the complex numbers can be described by their magnitude and some phase angle okay then this whole expression becomes exponential of PR times T times the magnitude of A1 times exponential J phi exponential J PIT plus exponential minus J phi because here we would have what A2 which is the complex conjugate of A1 times exponential J PIT okay so which results in A1 exponential PR times T exponential J PIT plus phi plus exponential minus J PIT plus phi okay you know that also exponential Jx plus exponential minus Jx is 2 times cos x so this sum is 2 times cosine of PI of T plus phi which basically gives us 2A1 exponential PRT exponential PIT plus phi okay so what do we have finally the entire natural response becomes a product of an exponential and a sinusoid okay so that is the qualitative difference I was trying to bring about okay there is a question about how to get the previously recorded lectures if you go to the NPTEL website you will see that all recorded lectures are available okay so you can go there and then get all of the lectures. So now let me just summarize the 3 cases the first one is when the quality factor is less than half or damping factor is greater than 1 in terms of the differential equation coefficients A1 square greater than 4A2 and the response is of the form A1 exponential P1T plus A2 exponential P2T A1 and A2 you choose from initial conditions and this particular condition where the damping factor is high that is damping factor is more than 1 is known as the over damped case and if I plot the natural response qualitatively okay it will look something like that let me plot all of them in the same plot later and the second case when the quality factor equals half and the damping factor equals 1 or in terms of the coefficients A1 square equals 4A2 this is known as the critically damped case and in this case the natural response again has 2 constants it is A1 plus A2T exponential P1T because P2 is identical to P1 okay and finally when the quality factor is more than half or the damping factor is less than 1 in terms of the coefficients A1 square is more than 4A2 this is known as the under damped case and in this case the P2 and P1 are complex conjugates of each other and the natural response is turns out of the form some constant exponential of PRT and exponential PIT plus phi okay. So again there are 2 constants here really there is the constant A1 and there is this constant phi and these have to be adjusted from initial conditions okay and what are PR and PI basically P2 and P1 are this P1 is PR plus j times PI it will be a complex number that is where the PR and PI come from okay these 2 constants and these 2 constants and this or that all of these are determined from initial conditions okay. So I hope this part is clear I will qualitatively show how these responses look like and why they are called over damped critically damped and under damped okay I will not go into much more detail about this but you can try it yourself I will try to determine A1 and A2 from initial conditions and get the total response okay by the way let me also describe what happens for the 3 cases in the 2 kinds of circuits over damped which means Q less than half or damping factor is I more than 1 okay and in case of series or we will see this means that basically you have a large resistance okay so if you work it out based on the formula for quality factor or damping factor this is what you will see parallel RLC value of R is small that is when you have over damped and critically damped means Q equals half or zeta equals 1 and under damped is when Q is more than half or zeta is less than 1 and the value of R is small in a series RLC case or large in the parallel RLC case okay. So let me take an example of some series RLC circuit okay so there will be a certain initial condition on the capacitor voltage and there will be a certain initial condition on the inductor current okay which basically can be thought of as initial condition on the derivative of the capacitor voltage okay and from these you can calculate all the responses I will assume the case with Vs equal to 0. So then let me imagine that for some value of RL and C the circuit is over damped that is the quality factor is less than half or the damping factor is more than half okay so I will plot Vc versus time starting from some initial condition Vc of 0 okay so what you would see is that for a certain initial condition on Vc of 0 and I love 0 the response may look something like this okay this is a typical response of an over damped case so this would be over damped and as you go on reducing the value of R okay let us say for some value of R it is over damped as you go on reducing the value of R at some point it becomes critically damped okay so for that the response tends to look like this okay so this would be critically damped and finally when it becomes over damped you see that again I think I made a mistake here this should be cosine okay this should be cosine Pi of t plus 5 and because of the presence of this cosine we will have a cosine sinusoidal response which has cycles right which goes alternately between positive and negative values and because of this exponential PRT the amplitude of the oscillation goes to 0 okay so what we would see would be something like this okay you will see some oscillations and then it can go off to 0 okay these are not to scale okay and also the response varies a little bit with the initial conditions but qualitatively this is what you would see and this happens in a series RLC circuit as R decreases it goes from being over damped to critically damped to under damped okay is this fine is there any questions I will take them now otherwise we can move on to the next topic then if you want to get the step response of a second order system you first calculate the steady state response okay this is based on open circuiting all capacitors and short circuiting all inductors and then you calculate the damping factor or the quality factor and from this you write the general form of the natural response the total response is natural response plus steady state response of the force response okay and the constants in the natural response either A1 and A2 or A1 and 5 these have to be adjusted from initial conditions this is fine so this is how the total step response of a second order system would be found what we will do next is to find out the response of these circuits whether it is RC or RLC to other kinds of time varying waveforms okay now we have analyzed them to some extent till now but we have considered only constant waveforms or steps which are of course varying but piecewise constants now signals in general can vary in more complicated fashion so what we will look at is the response of these signals to sinusoids which is a particular kind of time varying signal okay now we won't go into the details but it turns out that any signal of any shape can be constructed by combination of sinusoids okay that is by adding up sinusoids of different frequency and phase also now we are dealing with linear circuits so if the input is a sum of different sinusoids then we know that superposition applies we have to find the response to each of the sinusoids individually and then add up the responses to get the final response to the combination of the sinusoids okay so we can analyze the circuit for sinusoidal inputs with knowing fully well that for any other kind of input if we know its decomposition into sinusoids we will be able to tell the response also okay so that is why you find that most of the time either in analysis or in measurement the circuits are characterized using sinusoids okay so what we will do is we will look at the response to sinusoidal inputs now this can be done by solving the differential equation but we will take an easier route and show that what the relationships are show what the relationships are for each element when a sinusoid is applied okay and then from there what we will be able to do is directly from the circuit transform it into transform it in some way so that we can tell what the sinusoidal response is okay now there is one caveat here if we solve the differential equation we will see that it will have a certain natural response and a certain force response now it turns out that if you have a sinusoidal input the force response is also a sinusoid of the same frequency it is amplitude and phase can be different okay now with the method that I am talking about the natural response will not be computed at all okay the method I am going to outline where we transform each element R, L and C into something that is appropriate for sinusoidal steady state analysis it turns out that essentially we will be omitting the natural response completely so this will calculate only the steady state or the force to response to sinusoids but there is still okay it is still useful enough in practice because there are so many practical situations where you apply a sinusoid to a circuit and you wait for a while for the natural responses to die out and then you look at the output okay so it is still quite useful in practical context and it is also much much easier than solving the differential equation so that is why we do this thing okay and this entire business is known as either sinusoidal steady state analysis or phasor analysis the reasons for all of these things will become clear later okay we will talk about phasors later first I will show the sinusoidal steady state analysis okay so what is this all about so first of all let me apply a voltage which is just cos omega t across a resistor R okay what is the value of the current I please let me know I apply a sinusoidal voltage cos omega t across a resistor R what is the value of the current I so clearly a current I is V by R which is cos omega t divided by R okay now let us say I apply sin omega t across the same resistance R this let me call this I1 I1 will be V1 by R so V1 is cos omega t V2 is sin omega t so I2 will again be V2 by R okay we know the real relationship of a resistor this is sin omega t by R okay then now because this is a linear element okay superposition applies that is I applied V1 I have got I1 applied V2 I have got I2 so now if I apply let us say alpha 1 V1 plus alpha 2 V2 by linearity I expect the current to be alpha 1 I1 plus alpha 2 I2 okay now I will choose particular values of alphas which as you will see very easily will become will make it very convenient to analyze circuits I will choose alpha 1 to be 1 and alpha 2 to be j that is square root of minus 1 okay if I do that the applied voltage V which I call let us say V3 will be cos omega t plus j sin omega t right because it is cos omega t times 1 plus sin omega t times j which of course you know from basics of complex numbers is exponential j omega t okay so if you apply exponential j omega t the response will of course be I3 which is I1 plus j times I2 which is exponential j omega t divided by R okay now there is nothing surprising here I could have started off with exponential j omega t and said that the current is exponential j omega t divided by R because the current is simply voltage divided by the resistance but the interesting thing comes when we apply the same thing to capacitors and inductors right because initially we could always analyze resistance circuits somewhat easily right because we and I were proportional to each other and we had so many techniques to analyze even very complicated resistive networks like using nodal analysis and so on okay whereas once we had capacitors or inductors we ended up with differential equations which is definitely more difficult than solving algebraic equations so now this is trivial but it just illustrates the point I did it in a convoluted way instead of simply saying I will apply exponential j omega t because then you will not understand the motivation why I did that I applied cos omega t sin omega t and by superposition I constructed this exponential j omega t okay now let us do the same for capacitors and inductors and see what we get first let me take a capacitor and apply v1 equals cos omega t to it and what is the current i1 i1 is c times the time derivative of v1 which is basically minus omega c sin omega t and similarly if v2 is sin omega t that is I apply sin omega t across a capacitor a current i2 will flow okay which is c dv2 by dt which is basically plus omega c cos omega t now if I apply a third voltage v3 which is exponential j omega t and remember I do not have to solve for this separately I could I could have solved for this separately but I will first do it individually that is I imagine that this cos omega t and sin omega t are superposed I multiply cos omega t by 1 and sin omega t by j to get exponential j omega t the whole reason I am doing it this way is because I already told you that we will characterize the circuit with sinusoids we will use sinusoids to analyze and even in the lab to measure some things about our circuits so cos omega t and sin omega t are sinusoids and from that I will construct this some complex number exponential j omega t now that is an abstract thing which is really a mathematical quantity I cannot get exponential j omega t in the lab okay but it is still very useful to analyze using that we will see why now I will have this v3 which is exponential j omega t okay which is basically v1 plus j times v2 okay now the current I3 is I1 plus j times I2 okay which turns out to be omega c times minus sin omega t plus j cos omega t which you can see can also be written as j omega c times cos omega t plus j sin omega t which is basically j omega c exponential j omega t okay I could also have got this directly I3 which is c time derivative of exponential j omega t which is j omega c exponential j omega t okay now why did I do all this the point is the following first of all exponential j omega t can be thought of as superposition of cos omega t and sin omega t with some multiplying factors I multiplied cos omega t by 1 and sin omega t by j okay then the response to exponential j omega t is also a superposition of response to cos omega t and sin omega t okay now what I am trying to emphasize is that it is the response to cos omega t that I am interested in I apply cos omega t to some circuit and I want to find what the response is now in case of a capacitor I can still find it quite easily because it is very easy to differentiate v1 which is cos omega t but later we will see the circuits can get quite complicated okay now what happened I found this superposed response I3 by superposing this which is j omega c exponential j omega t okay or I could even differentiate it directly and I would get the same answer naturally okay they have to be consistent now the point is that if you look at this thing right the applied voltage is exponential j omega t and the current if you see it is proportional to exponential j omega t okay we have some constant it happens to be an imaginary number in this case but the point is it is some constant times exponential j omega t now this is not the case when I apply cos omega t when I apply cos omega t the response is sin omega t it is not something times cos omega t okay it looks more complicated I have to get it by differentiation but if I apply exponential j omega t I have shown using both ways that the response is some number times exponential j omega t okay it is proportional to the applied voltage and this happens to be just as in the resistors case okay in this case we have I3 to be 1 by R which is the conductance of the resistor times exponential j omega t okay the current is some number times the voltage the capacitor also has a current voltage relationship in the same form if the applied voltage is exponential j omega t okay so that is what makes it convenient but then what I am interested in is what happens when I apply cos omega t okay so I that is the thing that I will apply in the lab so that is what I want to know so now that is where this view point of superposition helps okay if you look at this excitation I have formed V1 plus j times V2 and let us say I am interested in the response to cos omega t okay this is my interest so now I have constructed V3 as superposition of V1 and V2 so naturally I3 the response to V3 is a superposition of this is the response to V1 plus j times the response to V2 okay let me in fact rewrite this I will write this as minus omega c sin omega t plus j omega c cos omega t okay remember I could get this answer much more easily by simply applying exponential j omega t and doing C dy dt of exponential j omega t but the point is I want to get back this quantity which is the response to cos omega t you see that the way this has been constructed V1 plus j times V2 okay the response also will be the response to V1 plus j times the response to V2. Now V1 and V2 are real quantities okay they are cos omega t or sin omega t and response to V1 is a real quantity it is some real voltage in the circuit response to V2 is also real quantity it is a some real voltage in the circuit okay so now this j this multiplier square root of minus 1 helps to keep the two responses separate okay you see what I am saying V1 is cos omega t V2 is sin omega t our superposition was V1 plus j times V2 so the response also will be response to V1 plus j times the response to V2 so the response to V1 will be the real part of the total response the response to V2 will be the imaginary part of the total response okay so I can calculate the response to exponential j omega t and take the real part to get response to cos omega t and if I wanted the response to sin omega t I could take the imaginary part we do not normally do that but we just take the real part I will explain why later I mean it is just an easy thing to do okay so we now have a much easier way of analyzing I will elaborate on this in the next lecture the reason it is easier is with exponential j omega t the relationship for the capacitor became somewhat like the resistor that is the current is just proportional to the voltage current is the voltage time some number okay instead of being this differential derivative and so on okay but from that we have to calculate the response to cos omega t and that is also easy okay the real part of that gives the response to cos omega t okay so from this we will be able to analyze any circuit consisting of R L and C when the applied voltages are sinusoid okay if there are any questions I will be happy to answer them now otherwise we will meet on Thursday I think also today there was a lot of lag between what I am saying and what was being received on the net hopefully you will be able to watch the recorded lecture and fill up any gaps that may be there okay thank you I will see you on Thursday


Hi, my name is Nicola Venerundi and as you already know if you read the newspaper this morning my channel just hit 1,000 Subscribers and I'm super happy about it, especially because in this month I got a lot of supports from both KD developers and users an amazing community and Every time I would publish a new video the one thing I would be most looking forward to would be the comments both in the YouTube section and in the reddit one so I even got some support emails and I totally did not expect to see so many people had Helping me producing this content. So you really deserve a big. Thank you I wanted to take this occasion to do something that wouldn't work if done with more or or less Subscribers that is to actually ask you directly. What kind of content would you like to see in my channel? Let me explain right now I'm mostly doing one how to do videos like how to do a plasma theme or how to configure a panel or an Uplit Devlogs or how I actually work for KDE and reviews or rather first looks to other distros or Desktop's so what would I like to improve first? I'd like to turn the first look into actual in depth reviews Then I'd like to start reviewing hardware as well And finally I'd like to show my face more because I believe it works better as an explaining aid being able to see my emotions and my hand gestures and an Italian so To do those things and it a Some contacts in Linux hardware manufacturers companies to actually ask to review some products or be enough money to actually buy Them by myself and then resolve them and Also see being able to get a better camera because what I'm using right now is quite a bad phone And I even got three lights to make it look decent But what would you like to see like for real? I want to know you've got comments Emails private messages feel free to tell me anything. I read them all I also have to say a big big. Thank you to all the patreons and Libra payers Who support me? I have this slide in and out section But it's not nearly enough to say how much I actually appreciate it and if you want to join the Libra payers Sounds cool community. You've got links in the description and To end this video. I wanted to do something. I've seen an Italian youtuber to do in his thank you videos Years and years ago Utobi he was called and that is to actually bow in front of the camera for like three minutes No video editing involved. So the only meaning take away from this video is Thank you everybody. I forgot to bring a clock down there I don't know how much three minutes are I'll take a guess I hope that nobody enters this room like right now. It would be weird It's weird. Anyway, I think I need to clear the I'm Niccolò Pinerandi as as you might have Hi, I'm Niccolò Pinerandi as Hi Carvers and I'm super happy about it Oh


Income tax 2022-2023, business expenses, travel and meals. Let's do some wealth preservation with some tax preparation. Support Accounting Instruction by clicking the link below, giving you a free month membership to all of the content on our website, broken out by category, further broken out by course. Each course then organized in a logical, reasonable fashion, making it much more easy to find what you need than can be done on a YouTube page. We also include added resources such as Excel practice problems, PDF files and more like QuickBooks backup files when applicable. So once again, click the link below for a free month membership to our website and all the content on it. Most of this information comes from the tax guide for small business for individuals who use Schedule C, Publication 334 Tax Year 2022. You can find on the IRS website, irs.gov, irs.gov. Looking at the income tax formula, we're focused on line one income. Remember in the first half of the income tax formula is in essence an income statement, but just to outline other forms and schedules flowing into these line items, one of those, the Schedule C. Having business income minus business expenses, the business net income flowing in in essence to line one income of our income tax formula. We note that the Schedule C flows into the Schedule 1, which flows into the first page of the form 1040, line number 8. The profit and loss or the Schedule C is called profit or loss from business, having an income statement format, income minus expenses. We're focused on the expenses here related to the travel and meals in particular. Now obviously the travel and meals is kind of a complicated topic because remember our general rule is that we can only have a deduction if it's an ordinary and necessary business item. And when we dive into the concept of meals and travel, we often have that fuzzy gray line between whether or not the meals and travel are necessary business expenses or whether they are personal. We also have had changes in the laws related to meals in particular. So we want to make sure that we do our best to properly allocate the travel and meals. All right, so travel and meals. This section briefly explains the kinds of travel and meal expenses you can deduct on Schedule C, travel expenses. These are the ordinary and necessary. There's those key terms again, remembering that a general expense you would think would be legitimate as a general rule. If it was ordinary and necessary or you needed it, you needed to consume something in order to generate the revenue. So that means we're going to be taxed on the net income as opposed to the gross income, which makes sense from an income tax system. So traveling away from home for your business. So that's a key point there, away from home. So these are the travel expenses. These are ordinary and necessary expenses of traveling away from home for your business. So you are traveling away from home. If both the following conditions are met, your duties require you to be away from the general area of your tax home defined later substantially longer than an ordinary day's work. So it's not just a commuting situation. You're going to be staying somewhere for a longer period of time, usually like an overnight situation. It's required for you to do it. What does that actually mean? Again, there can be kind of shady areas because you might say, hey, I was required to go to the Bahamas because I'm a photographer and I was taking pictures of beach models or something like that. And maybe you were, but that seems still seems kind of like a gray area from the perspective of someone working in the gray IRS office and whatnot. But so obviously what is going to be necessary for travel is going to be dependent upon the type of industry that you are in. So number one, you need to get sleep or rest to meet the demands of your work while away from home. These are the requirements. Number two, generally your tax home is your regular place of business regardless of where you maintain your family home. It includes the entire city or general area in which your business is located. You can see publication 463 for more information there. So the following is a brief discussion of the expenses you can deduct. So we've got the transportation. So now you're going somewhere, plane, bus, whatever you're doing to get there. And it's for work. So you would think then the transportation is legit business related, ordinary and necessary in that case. So you can deduct the cost of travel by airplane, train, bus or car between your home and your business destination. Note that the car gets a little bit messy because then you've got to deal with that whole thing about how are you deducting the cars and the mileage method versus the direct method and whatnot. And then so that gets, but obviously if you're traveling by airplane or train, it's fairly straightforward unless you have a situation where it's partial business, partial work. And then you have that gray area once again. Okay. So taxi, commuter bus, limousine. So you can deduct fares for these and other types of transportation between the airport and station and your hotel or between the hotel and your work location away from home. So baggage and shipping. You can deduct the cost of sending baggage and a sample or display material between your regular and temporary work locations, car or truck. You can deduct the cost of operating and maintaining your vehicle when traveling away from home on business. You can deduct actual expenses or the standard mileage rate. So here we go again with the car, which is a little bit more unusual. Now you're not just doing a commuting thing. You're not just visiting a client in your local area. You're traveling away from home, but using the car to do so as opposed to an airplane and whatnot. So once again, you can deduct actual expenses or the standard mileage rate discussed earlier under car and truck expenses as well as business related tolls and parking. So if you rent a car while away from home on business, you can deduct only the expense use portion of the expenses, the business use portion. So if you rent a car, you're deducting the business use. So meals and lodging. So you can deduct the cost of meals and lodging if your business trip is overnight or long enough that you need to stop for sleep or rest to properly perform your duties. So you can usually, you can use actual expenses or the standard meal allowance to calculate your deduction. So meals are another one that gets a little a little bit tricky. So they actually have like standard meal allowances, which are, which give you a little bit of a somewhat of a safe place to think about what the average meals are because you can imagine the situation where someone is traveling your business traveling and but you're having very extravagant meals, which is way over the top of what you really need to eat to sustain yourself for the business purpose of the meal, which you would think that would be kind of a personal thing as opposed to the business thing. And that's where, you know, great areas come in, same with the method of travel. If you get to deduct the travel, then people will have going first class then and that kind of stuff that that's where the tax code kind of manipulates people's behavior and whatnot in some ways. So in most cases, you can deduct only 50% of your meal expenses. And that was a, I think that's the general idea there being, look, you're going to eat. You would have had to eat the meals anyways. You may have, you may have been able, if you were home to cook your own meals and therefore it would have been cheaper or something. So maybe if you're away from home, you're having to pay for meals which are more expensive. So that I think that's the rationale of why they come to this 50% of meal expenses. So however, business meals are 100% deductible if the meals are food and beverages provided by a restaurant and paid or incurred after December 31st, 2020 and before January 1st, 2023. So you've got this somewhat ambiguity with the meals situation. If you want to dive into that in more detail, you can see publication 463 for additional information. So cleaning, so you can deduct the cost of dry cleaning and laundry while on your business trip because you got to look good. You got to have your suit dry cleaned and whatnot. It's like a uniform. You have to have it, it's got to be ready to roll. Otherwise people don't listen to you. Telephone, you can deduct the cost of business calls while on your business trip, including business communication by fax machine or other communication devices. Tips, you can deduct the tips you pay for any expense in this list. So more information, for more information about travel expenses, you can see publication 463. So reimbursing your employees for expenses.  How are you going to do that? You can have some kind of reimbursement of their business related expenses, right? And then there's going to be some standardization rules that you might be able to follow on these kind of reimbursement type of situations as well because you can imagine when you have a reimbursement situation, people trying to manipulate that kind of situation. So just to give you an idea how that, why that might happen, like if someone goes on a business trip or something like that and they're able to expend extravagantly and you reimburse them for the spending, you get the expense of the reimbursement and you're actually basically paying them over and above what was necessary for just the business trip. So you're kind of giving them wages in that case. So in other words, you can imagine a situation where people are trying to give people wages without being subject to taxes. Social security, right? Because you're kind of giving them income in the fact that you're allowing them to spend extravagantly beyond what would be necessary for the trip. You're reimbursing them for that extravagant kind of behavior. And if it's a reimbursement, it might not be included in income on the W-2, not subject to federal income tax, social security and Medicare. So you can see where there's going to have to be lines that'll be drawn to how this is going to work. So the reimbursement you deduct and the manner in which you deduct it depend in part on whether you would reimburse the expenses under an accountable plan or a non-accountable plan. So you can dive into more detail if you have this reimbursement kind of situation on the difference between the accountable plan and the non-accountable plan. For details, you can see chapter 11 of publication 535. That chapter explains accountable and non-accountable plans and tells you whether to report the reimbursement on your employee's W-2, right? So if you have to report the reimbursement on the W-2, then if it's on line one as income, it might be subject to taxes. So now when you have this reimbursement situation set up, you want to try to do it properly by the books here so that you can maximize the benefits of the reimbursement and properly account for it and do the whole thing. And if you're in that situation, again, take a look at the publication 535. You can find it on the IRS website, irs.gov, irs.gov.


This trustee August is hotter than ever at Appalachian Wireless, as they are slashing all normal contract pricing on all smartphones by 50% when you sign up for service. Better service, bigger saving, serving you for the last 25 years at Appalachian Wireless. Even though the campus at the University of Pikeville is bare now, after next week the sidewalks and classrooms will be full. With every new school year comes new students with lots of questions. However, U-Pike faculty and staff want students to know much will be going on and students shouldn't feel overwhelmed, especially incoming freshmen. After a new freshman move in on August 17th, they will be experiencing a freshman orientation filled with days in which they're going to be able to learn about campus, learn about the different clubs and organizations, as well as take part in a community service project. It's also okay if you haven't already registered. Just make sure to do so when you arrive on campus. Open registration will be August 18th and 19th. We'll be here from 8 to 5 on both days. You don't have to come both days just pick one and we will be set up in the bottom of the administration building and you can come and talk to us and we can get you started. You'll meet with all different departments that day so you get your class schedule and your ID card, your email will be set up. They will be taking ID pictures that day if they don't already have an ID. So it's like a one-stop shop. Most experience a lot of emotion when first coming to college. However, faculty and staff say in the end it's worth it.  Classes at UPIKE begin August 22nd. Reporting in Pikeville for EKB News, I'm Shelby Steele.